CN100426638C - Eddy current type speed reducer - Google Patents

Abstract

The invention aims to provide an eddy current type speed reducer capable of ensuring braking capability and preventing magnetic leakage. In a preferred embodiment of the invention, the eddy current retarder (1) comprises a first magnet ring (18) arranged opposite the brake rotor (3) and containing a plurality of permanent magnets (16) arranged at circumferential intervals, and a second magnet ring (7) arranged opposite said first magnet ring (18) and containing a plurality of permanent magnets (10) arranged at circumferential intervals, wherein the magnetic force of each permanent magnet (10) of said second magnet ring (7) is set to be greater than the total magnetic force of the one or more permanent magnets (16) of said first magnet ring (18) which serve as cooperating parts forming a magnetic circuit in a brake-off state. As a result, the magnetic flux leaking to the brake rotor (3) during the brake stop may be almost zero.

Description

Eddy current reducer

technical field

The present invention relates to an eddy current type speed reducer mainly suitable for use as a secondary brake of a large vehicle.

Background technique

Eddy current speed reducers have been used as secondary brakes for large vehicles such as trucks.

An example of a conventional eddy current type speed reducer will be described below with reference to FIGS. 15 and 16 .

The eddy current speed reducer 51 includes a drum-shaped brake rotor 53 installed on a rotating shaft 52 such as a vehicle drive shaft, and a drum-shaped brake rotor 53 arranged radially inside the brake rotor 53 and mounted on a fixed side such as a transmission case. Stator 54 (magnetic force source).

The stator 54 comprises a hollow housing 55 supported on the fixed side and two magnet rings 57 , 58 arranged inside the housing 55 .

The first magnet ring 57 is fixed so that it cannot rotate relative to the housing 55, and the second magnet ring 58 is arranged parallel to the first magnet ring 57 and is rotatably housed in the Inside the housing 55. The second magnet ring 58 is turned by the actuator 56 .

The first and second magnet rings 57, 58 respectively have support rings 59, 60 made of magnetic material and a plurality of permanent magnets 61, 62 mounted on the support rings 59, 60 at specified intervals in the circumferential direction. . The permanent magnets 61, 62 have pole surfaces at their radially opposite ends, and they are arranged such that the orientation of the pole surfaces differs between magnets adjacent in the circumferential direction.

A plurality of pole pieces 63 made of a magnetic material (ferrous material, etc.) are embedded in the outer peripheral wall of the case 55 at the same pitch in the circumferential direction.

When the deceleration braking of the eddy current reducer is stopped (OFF), the second magnet ring 58 is rotated by the actuator 56, and each permanent magnet 61 of the first magnet ring 57 and the The permanent magnets 62 of the second magnet ring 58 are placed in such a phase that they face each other with different magnetic poles. As a result, as shown in FIG. 15 , a short-circuited magnetic circuit W1 is formed between the first and second magnet rings 57 , 58 and the pole piece 63 . Therefore, no magnetic force acts on the brake rotor 53 and no eddy currents are generated. In other words, deceleration braking is not produced.

On the other hand, when the deceleration brake is activated (ON), the second magnet ring 58 is rotated, and the permanent magnets 61 of the first magnet ring 57 and the permanent magnets of the second magnet ring 58 62 face each other with the same poles. As a result, as shown in FIG. 16, the magnetic flux from the permanent magnets 61, 62 of the first and second magnet rings 57, 58 reaches the brake rotor 53 through the pole piece 63, and A magnetic circuit W2 is formed between the magnet rings 57 and 58 , the pole pieces 63 and the brake rotor 53 . Therefore, an eddy current is generated in the brake rotor 53 , and the deceleration braking of the rotating shaft 52 is realized through the interaction of the eddy current with the magnetic flux from the permanent magnets 61 , 62 .

Such an eddy current type speed reducer is described, for example, in Japanese Patent Laid-Open Publication No. H07-123697.

However, in such an eddy current type speed reducer, when it is desired to increase the braking capability, it is necessary to increase the magnetic force of the permanent magnets 61, 62. However, if the magnetic force of the magnets 61, 62 is increased, a problem arises that part of the magnetic flux leaks to the brake rotor 53 during the braking stop, forming a magnetic leakage circuit and causing slip braking.

Thus, in the process of improving the eddy current type speed reducer, the task of ensuring the braking capability when the brake is applied and also preventing the leakage of the magnetic force when the brake is stopped will be involved.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems and provide an eddy current type speed reducer capable of ensuring braking capability and preventing magnetic force leakage at the same time.

In one embodiment of the present invention, the eddy current speed reducer includes: a brake rotor installed on the rotating shaft; a first magnet ring, which includes an annular magnetic member disposed opposite to the brake rotor and spaced apart in the circumferential direction A plurality of permanent magnets embedded in the magnetic member; a second magnet ring disposed opposite to the first magnet ring on the opposite side of the brake rotor, which includes a plurality of permanent magnets arranged at intervals in the circumferential direction ; wherein the first magnet ring is located between the second magnet ring and the brake rotor, the magnetic force of each permanent magnet of the second magnet ring is set to be greater than that used to form during braking stop The total magnetic force of one or more permanent magnets of said first magnet ring of cooperating parts of the magnetic circuit.

In this embodiment, during a braking stop, the magnetic flux of each permanent magnet of the first magnet ring is almost completely attracted to each permanent magnet side of the second magnet ring. Thus, magnetic flux does not leak to the brake rotor side. As a result, the magnetic force between the permanent magnets of the first magnet ring and the second magnet ring can be increased and the objects of securing braking capability and preventing magnetic force leakage can be achieved.

Here, the area of the pole surface of the permanent magnets of the second magnet ring is set to be substantially equal to that of the first magnet ring forming a magnetic circuit together with the permanent magnets of the second magnet ring during the braking stop. The total area of the pole surfaces of the one or more permanent magnets, and the magnetic flux density of the permanent magnets of the second magnet ring may be configured to be greater than the magnetic flux density of the permanent magnets of the first magnet ring.

Optionally, the magnetic flux density of the permanent magnets of the second magnet ring can be set to be almost equal to the magnetic flux density of the permanent magnets of the first magnet ring, and the area of the pole surface of the permanent magnets of the second magnet ring is arranged to be greater than the total area of the pole surfaces of the one or more permanent magnets of the first magnet ring forming a magnetic circuit together with the permanent magnets of the second magnet ring during said braking stop.

In addition, the relative phase between the first magnet ring and the second magnet ring during braking stop may be set based on the fact that the permanent magnets of the second magnet ring and the first magnet ring The difference or ratio of magnetic force, magnetic flux density, or pole surface area between permanent magnets.

In another embodiment of the present invention, the eddy current reducer includes a brake rotor installed on the rotating shaft, an outer magnet ring disposed opposite to the inner side of the brake rotor, and a The inner magnet ring arranged on the inner side and opposite to it, the outer magnet ring includes a plurality of permanent magnets, which are arranged at intervals in the circumferential direction so that the magnetic poles facing each other in the circumferential direction have the same polarity; the inner magnet ring includes a plurality of permanent magnets arranged circumferentially at intervals so that the magnetic poles facing the outer magnet ring alternate circumferentially; wherein, in the brake-activated state, by making the outer magnet ring and the inner magnet ring in a specified phases facing each other to achieve a magnetic circuit between the outer and inner magnet rings and the brake rotor, and in the brake stopped state by rotating the outer magnet ring from the brake enabled state And/or the inner magnet ring passes through the specified phase to realize a magnetic circuit forming a short circuit between the outer magnet ring and the inner magnet ring; wherein the magnetic force of the permanent magnet of the inner magnet ring is set to be greater than being the total magnetic force of one or more permanent magnets of said outer magnet ring forming a cooperating part of a magnetic circuit with permanent magnets of said inner magnet ring during said braking stop; and, and in said braking stop state The magnetic flux leakage to the brake rotor is almost zero.

Here, the outer magnet ring may include an annular magnetic member and the plurality of permanent magnets embedded in the magnetic member at constant intervals in the circumferential direction, and a thin layer portion generated by the magnetic member may be formed in each radially outside of the permanent magnet.

In yet another embodiment, the eddy current reducer includes a braking rotor installed on the rotating shaft, a first magnet ring disposed opposite to the braking rotor, and a second magnet disposed opposite to the first magnet ring ring; the first magnet ring includes a plurality of permanent magnets arranged at intervals in the circumferential direction, and the permanent magnets have magnetic poles on the end surfaces of both sides in the circumferential direction; the second magnet ring includes A plurality of permanent magnets arranged at intervals, and the permanent magnets have magnetic poles on the end surfaces of both sides in the circumferential direction; wherein, the first magnet ring is located between the second magnet ring and the braking rotor Meanwhile, a ratio of the magnetic force of the magnets of the first magnet ring to the magnetic force of the magnets of the second magnet ring is set in a range of 1: about 1.2 to about 1.6.

Here, the magnetic forces per unit surface area of the magnets of the first magnet ring and the second magnet ring are set to be almost the same as each other, and the area of the pole surface of the magnets of the first magnet ring is the same as that of the second magnet ring. The area ratio of the pole surfaces of the magnets of the magnet ring is set in a range of 1:about 1.2 to about 1.6.

In addition, the axial length and the circumferential length of the magnets of the first magnet ring and the second magnet ring are respectively set to be approximately equal to each other; and the radial length of the magnets of the first magnet ring is the same as that of the second A ratio of radial lengths of the magnets of the magnet ring may be set within a range of 1:about 1.2 to about 1.6.

In another embodiment of the present invention, the eddy current reducer includes a brake rotor installed on the rotating shaft, an outer magnet ring disposed opposite to the inner side of the brake rotor, and an inner side of the outer magnet ring The inner magnet ring arranged opposite to it; the outer magnet ring includes a plurality of permanent magnets, and the plurality of permanent magnets are arranged at intervals in the circumferential direction so that the magnetic poles facing each other in the circumferential direction have the same magnetism, and the magnet ring includes a plurality of permanent magnets, the plurality of permanent magnets being spaced apart in the circumferential direction so that the magnetic poles facing each other in the circumferential direction have the same magnetism; wherein, in the brake activated state, by making the outer magnet ring The inner magnet rings face each other in a given phase to achieve a magnetic circuit between the outer and inner magnet rings and the brake rotor, and in the brake stopped state, by turning from the brake activated state The outer magnet ring and/or the inner magnet ring pass through the specified phase to realize a magnetic circuit forming a short circuit between the outer magnet ring and the inner magnet ring, wherein the magnetic force of the magnets of the outer magnet ring A ratio of the magnetic force of the magnets to the inner magnet ring is set in a range of 1: about 1.2 to about 1.6.

Here, the outer magnet ring may include an annular magnetic member and the plurality of permanent magnets embedded in the magnetic member at constant intervals in the circumferential direction, and a thin layer portion including the magnetic member may be formed in each radially outside of the permanent magnet.

A protrusion protruding radially outward may be formed in a portion of the magnetic member between the permanent magnets.

Description of drawings

By reading and understanding the following detailed description of the present invention, those skilled in the art will easily understand other objectives, features and implementation effects of the present invention.

Fig. 1 is a side sectional view showing an upper half of an eddy current reducer according to an embodiment of the present invention;

Fig. 2 is a partial front sectional view showing the state of the eddy current reducer shown in Fig. 1 during braking and stopping;

Fig. 3 is a partial front sectional view showing the state of the eddy current reducer shown in Fig. 1 during braking activation;

Figure 4 shows the relationship between the ratio of the magnetic force of the inner permanent magnet to the total force of the outer permanent magnet and the magnetic flux acting on the brake rotor during braking stop;

Fig. 5 is a partial front sectional view showing magnetic force leakage during a braking stop;

Figure 6 shows the relationship between the rotational phase of the inner magnet ring and the magnetic flux acting on the brake rotor;

Figure 7a is a side sectional view showing the upper half of an eddy current reducer according to another embodiment of the present invention;

Fig. 7b is a partial cutaway top view of the eddy current reducer shown in Fig. 7a;

Fig. 8 is a side sectional view showing an upper half of an eddy current reducer according to yet another embodiment of the present invention;

Fig. 9 is a partial side sectional view showing the state of the eddy current reducer shown in Fig. 8 during braking and stopping;

FIG. 10 is a partial side sectional view showing the state of the eddy current reducer shown in FIG. 8 during braking activation;

Fig. 11 shows the relationship between the ratio of the radial length of the permanent magnets of the first and second magnet rings and the magnetic flux of the outermost peripheral portion of the magnetic member during braking stop;

Figure 12 shows the relationship between the ratio of the radial lengths of the permanent magnets of the first and second magnet rings to the magnetic flux at the outermost peripheral portion of the magnetic member during braking activation;

Fig. 13 shows the relationship between the ratio of the radial length of the permanent magnets of the first and second magnet rings and the value obtained by dividing the magnetic flux by the total radial length of the permanent magnets;

Fig. 14 is a side sectional view showing an upper half of an eddy current reducer according to yet another embodiment of the present invention;

Fig. 15 is a side sectional view showing the upper half of a conventional eddy current speed reducer; and

Fig. 16 is a partial front sectional view showing a conventional eddy current type speed reducer.

Detailed ways

Preferred embodiments according to the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a side sectional view of an upper half of an eddy current type speed reducer according to the present invention. Fig. 2 is a partial front sectional view showing the state of the eddy current type speed reducer during braking stop. Fig. 3 is a partial front sectional view showing the state of the eddy current type speed reducer during brake activation.

As shown in FIG. 1 , an eddy current speed reducer 1 includes a drum-shaped brake rotor 3 installed on a rotating shaft 2 such as a vehicle drive shaft, and a drum-shaped brake rotor 3 arranged radially on the inner side of the brake rotor 3 and mounted on such as Stator 4 (source of magnetic force) on the fixed side of the gearbox or the like. The deceleration braking of the rotating shaft 2 is induced by supplying magnetic force from the stator 4 to the rotor 3 to generate an eddy current inside the rotor 3 , and the deceleration braking is canceled by shielding the magnetic force inside the stator 4 move.

The stator 4 has a hollow housing 5 supported on the fixed side, and an outer magnet ring (first magnet ring) 18 is mounted on the housing opposite the inner surface of the brake rotor 3 5 on the peripheral wall. As shown in Figures 2 and 3, the outer magnet ring 18 has an annular magnetic member 17 (such as a laminate of electromagnetic steel plates, iron blocks, etc.) A plurality of permanent magnets 16 within said magnetic member 17 . Each permanent magnet 16 has magnetic pole surfaces at both ends thereof in the circumferential direction, and adjacent permanent magnets 16 are arranged to face each other with the same magnetic poles. A thin-layer portion 13 produced by a magnetic member 17 is formed on the radially outer side of each permanent magnet 16 .

An inner magnet ring (second magnet ring) 7 is housed inside the housing 5 . On the opposite side (radially inward) of the brake rotor 3 , the inner magnet ring 7 faces the outer magnet ring 18 . The inner magnet ring 7 is arranged to be rotatable relative to the housing 5 via a bush 6 and is rotated by an actuator 8 (for example a hydraulic cylinder) arranged on the side of the housing 5 . The inner magnet ring 7 includes a support ring 9, a magnetic member 11 and a plurality of permanent magnets 10, the support ring is made of a non-magnetic body (austenitic stainless steel, etc.), and the magnetic member (such as a laminate of electromagnetic steel plates, Iron blocks, etc.) are arranged on the outer periphery of the support ring 9, and the plurality of permanent magnets are embedded in the magnetic member 11 at constant intervals along the circumferential direction. The permanent magnets 10 have pole surfaces at both radial ends thereof, and the poles which are arranged to face the outer magnet ring 18 are alternately different between the magnets 10 adjacent in the circumferential direction. The circumferential length of the permanent magnets 10 of the inner magnet ring 7 is substantially set to be substantially equal to the spacing between the permanent magnets 16 of the outer magnet ring 18 . In the magnetic member 11 , a rectangular opening 15 is formed in a portion between the permanent magnets 10 .

When the deceleration braking of the eddy current reducer stops, the inner magnet ring 7 is rotated by the actuator 8, and as shown in FIG. 2 , each permanent magnet 10 of the inner magnet ring 7 is placed Between the respective permanent magnets 16 of the outer magnet ring 18, and the permanent magnets 10 of the inner magnet ring 7 and the permanent magnets 16 of the outer magnet ring 18 are arranged to face each other with different poles phase. As a result, short magnetic circuits 31 are formed between the permanent magnets 10 and the magnetic member 11 of the inner magnet ring 7 and between the permanent magnets 16 and the magnetic member 17 of the outer magnet ring 18 . Consequently, no magnetic force acts on the brake rotor 3 and no deceleration braking occurs. At this time, the magnetic flux flowing from the permanent magnet 16 of the outer magnet ring 18 to the brake rotor 3 forms a short circuit (short circuit) through the thin layer part 13, and can effectively prevent magnetic force from leaking to the brake rotor 3.

On the other hand, when the deceleration brake is activated, the inner magnet ring 7 is rotated, and as shown in FIG. 3 , each permanent magnet 10 of the inner magnet ring 7 is placed in the Between the permanent magnets 16 , and the permanent magnets 10 of the inner magnet ring 7 and the permanent magnets 16 of the outer magnet ring 18 are arranged in phases facing each other with the same magnetic poles. As a result, magnetic circuits 32 , 33 are formed between the permanent magnets 10 , 16 , the magnetic members 11 , 17 and the brake rotor 3 of the inner and outer magnet rings 7 , 18 , respectively. Therefore, an eddy current is generated in the brake rotor 3 , and the deceleration braking of the rotating shaft 2 is realized by the eddy current interacting with the magnetic flux from the permanent magnets 10 , 16 . At this time, since the opening 15 has been formed in the magnetic member 11 of the inner magnet ring 7 , the magnetic flux from the permanent magnet 10 is prevented from passing through the magnetic member 11 to form a short circuit.

The inventors have found that in such an eddy current reducer, if the magnetic force of the permanent magnets 10 of the inner magnet ring 7 is configured to be greater than the total magnetic force of the permanent magnets 16 of the outer magnet ring 18, the The magnetic leakage during a braking stop can be almost zero, wherein the permanent magnet 16 and the permanent magnet 10 form a magnetic circuit with each other during a braking stop (the state shown in FIG. 2 ). More specifically, in this embodiment, during a braking stop, a magnetic circuit is formed by one inner permanent magnet 10 and two permanent magnets 16 on both sides thereof. Therefore, magnetic force leakage can be eliminated by setting the magnetic force W2 of the permanent magnet 10 to be greater than twice the magnetic force W1 of each outer permanent magnet 16 (W2>2×W1).

Methods of generating different magnetic fluxes (flux per unit surface area) within the permanent magnets 10, 16, methods of producing permanent magnets 10, 16 with different pole surface areas, or combinations of these methods may be employed such that all The magnetic force of the inner permanent magnet 10 is greater than the magnetic force of the outer permanent magnet 16 .

For example, the area of the pole surface (radial end surface) of the inner magnet 10 is set approximately equal to the total area of the pole surfaces of the two outer permanent magnets 16 serving as cooperating parts of the magnetic circuit during braking stop, That is, when the area of the magnetic pole surface of each inner permanent magnet 10 is configured to be equal to twice the area of the magnetic pole surface of each permanent magnet 16, if the magnetic flux density of the inner permanent magnet 10 is higher than that of the outer permanent magnet 16 If the magnetic flux density is low, the magnetic force of the inner permanent magnet 10 can be made larger than the total magnetic force of the two outer permanent magnets 16 serving as cooperating parts forming a magnetic circuit.

Furthermore, when the magnetic flux densities of each inner permanent magnet 10 and each outer permanent magnet 16 are set approximately equal to each other, if the area of the magnetic pole surface of the inner permanent magnet 10 is made larger than the magnetic flux density formed during braking stop, The total area of the pole surfaces of the two permanent magnets 16 of the circuit, the magnetic force of the inner permanent magnet 10 can be configured to be greater than the total magnetic force of the two outer permanent magnets 16 used as a cooperating part forming the magnetic circuit. For example, when the axial length T1 of the outer permanent magnet 16 is set to be substantially equal to the axial length T2 of the inner permanent magnet 10, the circumferential length L2 of the inner permanent magnet 10 (see FIG. 2 ) may be greater than The outer permanent magnet 16 is twice the radial length L1 (L2>2×L1). Optionally, when the outer peripheral length L2 of the inner permanent magnet 10 is made approximately equal to twice the radial length L1 of the outer permanent magnet 16, the axial length T2 of the inner permanent magnet 10 may be greater than the The axial length T1 of the outer permanent magnet 16 (T2>T1).

Furthermore, even if the magnetic flux densities of each inner permanent magnet 10 and each outer permanent magnet 16 are set to be almost equal to each other and the area of the magnetic pole surface of the inner permanent magnet 10 is made equal to the magnetic pole of each outer permanent magnet 16 When the surface is twice the area, if the radial length of the inner permanent magnet 10 is made greater than the circumferential length of the outer permanent magnet 16, then the magnetic force of the inner permanent magnet 10 can be made greater than that of the outer permanent magnet 16 magnets. In other words, the volume of the inner permanent magnet 10 can be made more than twice the volume of the outer permanent magnet 16 .

The present inventors have confirmed the case of magnetic force leakage by changing the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of the outer permanent magnet 16 serving as a cooperating part forming a magnetic circuit during the braking stop . These results are shown in FIG. 4 . Here, by making the magnetic flux density (permeability) of the inner and outer magnet rings 10, 16 almost the same as each other and changing the area of the pole surface of the inner permanent magnet 10 and the magnetic pole surface of each outer permanent magnet 16 The ratio of the total area to carry out the experiment. Here, experiments were conducted by varying the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of the respective outer permanent magnets 16 within a range of 1.1 to 1.7. The ratio of 1.0 means that the magnetic force of the inner permanent magnet 10 is equal to twice the magnetic force of each of the outer permanent magnets 16 .

In the figure, the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of each outer permanent magnet 16 is plotted on the abscissa, and the ratio of the magnetic force of the permanent magnets 16 to the outer sides is plotted on the abscissa, and the ratio of the magnetic force of the permanent magnets 16 to the outside is plotted on the abscissa. The magnetic flux on the brake rotor 3.

As shown in the figure, when the aforementioned ratio is 1.1, the magnetic flux acting on the brake rotor 3 during braking stop is generated to a certain degree on the positive side (positive region), and then gradually increases as the ratio increases. decrease. When the ratio is about 1.4, the magnetic flux is almost zero, and if the ratio exceeds 1.4, magnetic flux is generated on the negative side (negative region).

When said ratio is significantly less than 1.4, a positive magnetic flux acts on said brake rotor 3 because the force attracting the magnetic flux of the outer permanent magnet 16 from the inner permanent magnet 10 is relatively small and, as shown by the dotted line W3 in FIG. 5 , part of the magnetic flux of the outer permanent magnet 16 leaks to the brake rotor 3 and forms a magnetic flux leakage circuit.

Furthermore, a ratio of 1.4 means that the entire magnetic flux of the outer permanent magnets 16 is attracted to the inner permanent magnets 10 and practically no magnetic flux leaks into the brake rotor 3 . Thus, if the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of the outer permanent magnets 16 is made to be about 1.4, magnetic force leakage during braking stops can be almost completely eliminated.

When the ratio significantly exceeds 1.4, negative magnetic flux acts on the brake rotor 3 because the magnetic force of the inner permanent magnet 10 is too large, and as shown by the dotted line W4 in FIG. 5 , the inner permanent magnet Part of the magnetic flux of 10 leaks to the brake rotor 3 and forms a magnetic leakage circuit. In other words, since the magnetic leakage circuit W4 appears in the opposite direction to the magnetic leakage circuit W3 generated by the outer permanent magnet 16, the magnetic flux is set to a negative value.

As a result, if the magnetic force of the inner permanent magnet 10 is configured to be greater than the total magnetic force of the outer permanent magnets 16 forming a magnetic circuit together with the inner permanent magnet 10 in the braking stop state, Magnetic force leakage due to the permanent magnet 16 can be eliminated. However, it is clear that if the magnetic force of the inner permanent magnet 10 is too large, a flux leakage circuit caused by the inner permanent magnet 10 is generated.

Due to the optimum ratio, which makes it possible to make the leakage of magnetic force almost zero, it obviously varies according to the structure of the eddy current reducer and the size of the inner and outer permanent magnets 10, 16, so the ratio is preferably according to the eddy current Set correctly for each type of reducer.

Furthermore, the inventors have found that by making the magnetic force of the inner permanent magnet 10 greater than the total magnetic force of the outer permanent magnets 16 forming a magnetic circuit together with the inner permanent magnet 10 in the braking stop state, even Magnetic leakage is more reliably prevented, and this can also be achieved by setting the relative phase between the inner magnet ring 7 and the outer magnet ring 18 during braking stops, that is, the inner permanent magnet 10 and the outer The relative phase of the permanent magnet 16 is realized. These are described below.

Figure 6 shows the analytical action when the inner magnet ring 7 is gradually turned from the brake-activated state, in case the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of the outer permanent magnet 16 is greater than 1.5 The resulting magnetic flux on the brake rotor 3 .

In the figure, the rotation angle of the inner permanent magnet 7 is plotted on the abscissa, and an angle of 0° corresponds to the phase of the brake activation state. In other words, in this state, as shown in FIG. 3 , each inner permanent magnet 10 is positioned precisely in the middle of the corresponding outer permanent magnet 16 , and the permanent magnets face each other with the same magnetic poles. The angle of 11° represents the phase of one span of rotation of the inner magnet ring 7 past the inner permanent magnet 10 . In other words, in this state, as shown in FIG. 2 , each inner permanent magnet 10 is positioned precisely in the middle of the corresponding outer permanent magnet 16 , and the permanent magnets face each other with different magnetic poles.

Next, as shown in FIG. 6 , as the inner magnet ring 7 rotates from 0°, the magnetic flux acting on the brake rotor 3 gradually decreases. Furthermore, when the inner magnet ring 7 is rotated through about 8.5°, the magnetic flux is almost zero. If the magnet ring 7 is turned further, a negative magnetic flux (magnetic flux in the opposite direction) acts on the brake rotor 3 . Thus, when the magnetic force of the inner permanent magnets 10 is configured to be 1.5 times the total magnetic force of the outer permanent magnets 16, by turning the inner magnet ring 7 during a braking stop slightly less than the A phase of a span of 10 (approximately 8.5° for a span of 11°) can almost completely eliminate the magnetic leakage.

In the above test as shown in Figure 4, the inner magnet ring 7 was rotated through one span of the inner permanent magnets 10 during a braking stop. Thus, when the magnetic force of the inner permanent magnet 10 is about 1.4 times the total magnetic force of the outer permanent magnets 16, if the rotational phase of the inner magnet ring 7 is configured to be equal to the outer permanent magnets 16 during braking stop One span of the inner permanent magnet 10 can almost completely eliminate magnetic force leakage.

Thus, the rotation angle of the inner magnet ring 7 at which the magnetic force leakage can be minimized varies depending on the difference (or ratio) between the magnetic force of the inner permanent magnet 10 and the total magnetic force of the outer permanent magnets 16 . Thus, based on the difference (ratio) of the magnetic force, magnetic flux density, or pole surface area between the inner permanent magnet 10 and the outer permanent magnet 16, the outer magnet ring 18 and the inner magnet ring 18 are set in the braking stop state. The relative phases between the rings 7 can more reliably prevent magnetic leakage. Based on various experiments, the present inventors have confirmed that the rotation of the inner magnet ring 7 during a braking stop as the magnetic force of the inner permanent magnet 10 becomes greater than the total magnetic force of the outer permanent magnets 16 phase can be reduced.

The above results show that by setting the phase of the inner magnet ring 7 corresponding to the ratio of the magnetic force of the inner permanent magnet 10 to the total magnetic force of the outer permanent magnets 16 during the braking stop, the braking effect during the braking stop can be achieved. Mobility can be secured, and magnetic force leakage during braking stops can be prevented.

The reason for this is as follows. First, an improvement in braking capability during a braking stop can be obtained by increasing the magnetic force of the inner permanent magnet 10 because the magnetic flux acting on the brake rotor 3 can be increased. However, according to FIG. 4 as follows, when the rotational phase of the inner magnet ring 7 is equal to 1 span of each inner permanent magnet 10, if the magnetic force of the inner permanent magnet 10 becomes too large (here, if its is configured to exceed 1.4 times the total magnetic force of the outer permanent magnet 16), a magnetic force leakage by the inner permanent magnet 10 occurs during a braking stop. Therefore, this magnetic leakage is avoided by reducing the rotational phase of the inner permanent magnet by less than 1 span. In other words, an improvement in braking capability is obtained by increasing the magnetic force of the inner permanent magnet 10 , while an improvement in braking capability is obtained based on the difference (or ratio) of the magnetic force between the inner permanent magnet 10 and the outer permanent magnet 16 . By setting the rotation phase of the inner magnet ring 7, the magnetic leakage can be zero.

In addition, the above-described embodiment is just an example, and various modifications thereof are possible.

For example, in the above embodiment, the structure in which the inner magnet ring 7 is rotated has been described, but the present invention may also adopt a structure in which the inner magnet ring 7 is fixed and the outer magnet ring 18 is rotated.

In addition, as shown in FIGS. 7a and 7b, the present invention can also employ an eddy current type speed reducer of the type equipped with a disc brake rotor 40 . In this structure, the housing 41 is installed on the fixed side opposite from the side portion to the brake rotor 40, and the first magnet ring 42 (equivalent to the outer magnet ring 18 shown in FIG. 1 ) is installed on the fixed side. on the casing 41. A second magnet ring 43 (equivalent to the inner magnet ring 7 shown in FIG. 1 ) is rotatably disposed inside the housing 41 and faces from the opposite side of the brake rotor 40. The first magnet ring 42 . The first magnet ring 42 includes a plurality of permanent magnets 44 arranged at prescribed intervals in the circumferential direction, and they are set such that magnetic poles facing each other in the circumferential direction have the same polarity. The second magnet ring 43 includes a plurality of permanent magnets 45 arranged at a prescribed interval in the circumferential direction, and they are set so that the respective magnetic poles facing the first magnet ring 42 are opposite to each other in the circumferential direction.

In this kind of eddy current speed reducer, also, the magnetic force of each permanent magnet 45 configured as the second magnet ring 43 under the condition of the set ratio is greater than that of the permanent magnet 45 forming the magnetic circuit together with it in the braking stop state. The total magnetic force of each magnet 44 of the first magnet ring 42, and by reasonably setting the relative phase between the first magnet ring 42 and the second magnet ring 43 during a braking stop corresponds to this ratio , Can reliably prevent magnetic leakage.

Another embodiment of the present invention will be described below with reference to FIGS. 8 to 10 . Fig. 8 is a side sectional view of the upper half of the eddy current type speed reducer of this embodiment. FIG. 9 is a partial front sectional view showing the state of the eddy current type speed reducer shown in FIG. 8 during braking stop. Fig. 10 is a partial front sectional view showing the state of the eddy current type speed reducer shown in Fig. 8 during braking activation.

As shown in FIG. 8 , the eddy current reducer 1 includes a drum-shaped brake rotor 3 installed on a rotating shaft 2 such as a vehicle drive shaft, and a drum-shaped brake rotor 3 arranged radially on the inside of the brake rotor 3 and installed Stator 4 (source of magnetic force) on a fixed side such as a gearbox. The deceleration braking of the rotating shaft 2 is induced by supplying magnetic force from the stator 4 to the rotor 3 to generate an eddy current inside the rotor 3 , and the deceleration braking is canceled by shielding the magnetic force inside the stator 4 move.

The stator 4 comprises a hollow housing 5 supported on the fixed side, and an outer magnet ring (first magnet ring) 18 is mounted in the housing opposite the inner surface of the brake rotor 3 On the peripheral wall of the body 5. As shown in Figures 9 and 10, the outer magnet ring 18 includes a magnetic member 17 (such as a laminate of electromagnetic steel plates, iron blocks, etc.) A plurality of permanent magnets 16 inside the magnetic member 17 . Each permanent magnet 16 has magnetic poles at both ends thereof in the circumferential direction and adjacent permanent magnets 16 are set to face each other with the same magnetic poles. The thin-layer portion 13 constituting the magnetic member 17 is formed on the radially outer side of each permanent magnet 16 . Protrusions 14 protruding radially outward are formed in the magnetic member 17 between the permanent magnets 16 .

An inner magnet ring (second magnet ring) 7 like the outer magnet ring 18 is rotatably accommodated in the housing 5 via a bush 6 . The inner magnet ring 7 is arranged to face the outer magnet ring 18 from the side opposite to the brake rotor 3 (radially inward), and the inner magnet ring is arranged on the side of the housing 5 by The actuator 8 (for example, a hydraulic cylinder) on the cylinder is rotated. The inner magnet ring 7 includes a support ring 9, a magnetic member 11 and a plurality of permanent magnets 10, the support ring is made of a non-magnetic body (austenitic stainless steel, etc.), and the magnetic member (such as a laminate of electromagnetic steel plates, Iron blocks, etc.) are arranged on the outer periphery of the support ring 9, and the plurality of permanent magnets are embedded in the magnetic member 11 at constant intervals along the circumferential direction. Each permanent magnet 10 has magnetic poles at both end portions thereof in the circumferential direction, and they are arranged such that adjacent permanent magnets 10 face each other with the same magnetic poles. A thin-layer portion 12 constituting the magnetic member 11 is formed on the radially outer side of each permanent magnet 10 . The respective spans of the respective permanent magnets 10, 16 of the inner and outer magnet rings 7, 18 are set substantially the same as each other.

When the deceleration braking of the eddy current reducer stops, the inner magnet ring 7 is rotated by the actuator 8, and as shown in FIG. 9 , each permanent magnet 10 of the inner magnet ring 7 is connected to the Each permanent magnet 16 of the outer magnet ring 8 faces each other with mutually different magnetic poles. As a result, short-circuited magnetic circuits 31 are formed between each permanent magnet 10 of the inner magnet ring 7 and the magnetic member 11 and between each permanent magnet 16 of the outer magnet ring 18 and the magnetic member 11 . Thus, no magnetic force acts on the brake rotor 3 and no deceleration braking occurs. At this time, the magnetic flux flowing from each permanent magnet 16 of the outer magnet ring 18 to the brake rotor 3 passes through the thin layer portion 13 to form a short circuit. And effectively prevent the magnetic force from leaking to the brake rotor 3 .

On the other hand, when the deceleration brake is activated, the inner magnet ring 7 is rotated, and as shown in FIG. 16 are made to face each other with the same magnetic poles. As a result, magnetic circuits 32 , 33 are formed between the permanent magnets 10 , 16 , the magnetic members 11 , 17 and the brake rotor 3 of the inner and outer magnet rings 7 , 18 , respectively. Thus, an eddy current is generated in the brake rotor 3 , and the deceleration braking of the rotating shaft 2 is realized through the interaction of the eddy current with the magnetic flux from the permanent magnets 10 , 16 . At this time, since the protrusions 14 protruding radially outward are formed within the portion of the magnetic member 17 disposed between the permanent magnets 16 , the air between the magnetic member 17 and the brake rotor 3 There is little clearance and high stopping power is obtained.

The present inventors have found that in such an eddy current speed reducer, by correctly setting the ratio of the magnetic forces of the permanent magnets 10 of the inner magnet ring 7 to the permanent magnets 16 of the outer magnet ring 18, the braking capability can be ensured And it can also effectively prevent magnetic leakage. More specifically, by making the magnetic force of the permanent magnets 10 of the inner magnet ring 7 larger than the magnetic force of the permanent magnets 16 of the outer magnet ring 18 by configuring with a specified ratio, the braking capability can be effectively ensured and at the same time it can be effectively prevented Magnetic leak.

The present inventor has also carried out various experiments, namely by changing the ratio of the magnetic force of the permanent magnet 16 of the outer magnet ring 18 and the magnetic force of the permanent magnet 10 of the inner magnet ring 7 to find the optimum value of the ratio. value. Here, by combining the axial length (length from left to right as shown in FIG. 8 ) and the circumferential length (length from left to right as shown in FIG. 9 and FIG. length) were set so that they were almost equal to each other and the radial lengths L1, L2 (see FIG. 9 ) of the permanent magnets 10, 16 were changed to carry out these experiments. Thus, by changing the radial length L1 , L2 of the permanent magnet 10 , 16 the area of the pole surface of the permanent magnet 10 , 16 can be changed. Since the permanent magnets 10, 16 are used having approximately the same magnetic flux per surface area, the magnetic force of the permanent magnets 10, 16 is approximately proportional to the area of the pole surface.

The test results are shown in Fig. 11 to Fig. 13 .

FIG. 11 shows analysis results regarding the magnetic flux density of the outermost peripheral portion B (see FIG. 9 ) of the magnetic member 17 during braking stop, and is used to judge magnetic force leakage during braking stop. FIG. 12 shows the analysis results regarding the magnetic flux density of the outermost peripheral portion B of the magnetic member 17 during brake activation, and is used to judge the braking capability. 13 shows the value obtained by dividing the magnetic flux density of the outermost peripheral portion B of the magnetic member 17 by the total radial length (L1+L2) of the permanent magnets 10, 16 during brake activation, and used for Judge braking efficiency.

Three types of radial lengths L1 of the permanent magnets 16 of the outer magnet ring 18: 5, 10 and 15 mm were used as test conditions and the radial length L2 of the permanent magnets 10 of the inner magnet ring 7 was the same as the The ratio (L2/L1) of the radial length L1 is varied in the range of 0.8 to 2.2. In Fig. 11 to Fig. 13, the line drawn by the square point is the result obtained when the radial length L1 of the permanent magnet 16 is 5 mm, and the line drawn by the rhombus point is when the length is 10 mm The results obtained, and the line drawn by the triangle points are the results obtained when the length is 15mm.

First, as shown in FIG. 11 , the ratio (L2/L1) of the radial length L2 of the permanent magnets 10 of the inner magnet ring 7 to the radial length L1 of the permanent magnets 16 of the outer magnet ring 18 is selected. When the ratio is about 1.4, the leakage magnetic flux is almost zero, and when the ratio is higher or lower, the leakage magnetic flux gradually increases. In other words, if the ratio of the magnetic force of the permanent magnet 10 to the permanent magnet 16 is set close to 1.4, more specifically, in the range from about 1.2 to about 1.6, the magnetic flux leakage can be almost or completely eliminated. If the ratio is too small, the magnetic flux leakage increases significantly because the force of the permanent magnets 10 of the inner magnet ring 7 that attracts the magnetic flux of the permanent magnets 16 of the outer magnet ring 18 decreases and the force of the permanent magnets 16 decreases. Part of the magnetic flux leaks into the brake rotor 3 . On the other hand, if the ratio is too large, the leakage flux increases significantly because the permanent magnets 10 of the inner magnet ring 7 become stronger and part of their flux leaks to the brake rotor 3 . The above range of 1.2 to 1.6 can be said to be the range within which almost all of the magnetic flux of the permanent magnets 16 of the outer magnet ring 18 is attracted to the permanent magnets 10 of the inner magnet ring 7 and The magnetic flux of the permanent magnets 10 of the inner magnet ring 7 flows to the brake rotor 3 .

Furthermore, the curve shown in FIG. 11 confirms that the smaller the radial length L1 of the permanent magnets 16 of the outer magnet ring 18 , the larger the area of low leakage flux.

Furthermore, as shown in FIG. 12, it is clear that the braking force during brake activation varies with the radial length L2 of the permanent magnets 10 of the inner magnet ring 7 and the diameter of the permanent magnets 16 of the outer magnet ring 18. The ratio to the length L1 increases (ie, as the radial length L2 of the permanent magnet 10 increases). Furthermore, it is clear that the greater the radial length L1 of the permanent magnets 16 of said outer magnet ring 18, the greater the braking force. In other words, these results also confirm that the greater the magnetic force of the permanent magnets 10, 16, the greater the braking force.

Furthermore, as shown in FIG. 13 , it is clear that the magnetic flux per unit length (braking efficiency) of the magnets is approximately constant and does not depend on the radial length L1 of the permanent magnets 16 of the outer magnet ring 18 when it is 10 mm. The aforementioned ratio (L2/L1), the magnetic flux per unit length of the magnet increases with the increase of the ratio when the radial length L1 of the permanent magnet 16 is 5mm, and the magnetic flux per unit length of the magnet When the radial length of the permanent magnet 16 is 15 mm, it decreases with the increase of the ratio. In other words, when the radial length L1 of the permanent magnet 16 of the outer magnet ring 18 is 15mm, compared with the permanent magnet 10 of the inner permanent magnet 7, the permanent magnet 16 of the outer magnet ring 18 Under the action, more braking torque is produced, and when the radial length L1 of the permanent magnet 16 of the outer magnet ring 18 is 5mm, compared with the permanent magnet 16 of the outer permanent magnet 18, the inner magnet The permanent magnet 10 of the ring 7 produces more braking torque.

The above results confirm that if the ratio of the magnetic force of the permanent magnets 10 of the inner magnet ring 7 to the magnetic force of the permanent magnets 16 of the outer magnet ring 18 is set in the range of 1: about 1.2 to about 1.6, it is ensured that The braking force is equal to or higher than conventional systems, while at the same time almost completely or completely preventing magnetic leakage.

In addition, when actually designing the eddy-current reducer, the aforementioned ratio can be set according to the idea of giving priority to preventing magnetic force leakage and ensuring braking force. In other words, if the prevention of magnetic force leakage is more important, the ratio can be set as close to 1.4, and if the braking force is more important, the ratio can be set as close to 1.6 as possible. In any case, if the ratio is in the range of about 1.2 to about 1.6, both the prevention of magnetic force leakage and the guaranteed braking force can be ensured at a relatively high level.

Various modifications to the above-described embodiments can be considered.

For example, in the above embodiment, the case of setting the ratio of the radial lengths L1, L2 of the permanent magnets 16, 10 of the outer and inner magnet rings 18, 7 was explained, but the present invention is not limited to this feature. In other words, since the ratio of the magnetic forces of the permanent magnet 10 and the permanent magnet 16 can be set within the above-mentioned range, the ratio of the axial thickness can be set within the range or the strength of each magnet ( The ratio of magnetic force per unit surface area) can be set within this range.

In addition, in the above embodiment, the structure in which the inner magnet ring 7 is rotated is described, but the present invention may also employ a structure in which the inner magnet ring 7 is fixed and the outer magnet ring 18 is rotated.

In addition, as shown in FIG. 14, the present invention can also employ an eddy current type speed reducer of the type equipped with a disc brake rotor 40. In this structure, a housing 41 is installed on the fixed side and opposite to the brake rotor 40 from the side, and a first magnet ring 42 (equivalent to the outer magnet ring 18 shown in FIG. 8 ) is installed on the housing. body 41. In addition, a second magnet ring 43 (equivalent to the inner magnet ring 7 shown in FIG. 8 ) is rotatably disposed inside the housing 41 so as to face the first magnet ring from the opposite side of the brake rotor 40. 42. Similar to the outer and inner magnet rings 18, 7 as shown in FIG. The magnetic poles arranged to face each other in the circumferential direction have the same polarity.

In such an eddy current reducer, also, by setting the ratio of the magnetic force of the permanent magnet 45 of the second magnet ring 43 to the magnetic force of the permanent magnet 44 of the first magnet ring 42 at 1: about 1.2 In the range of about 1.6, the same effect as that of the above-mentioned embodiment can be obtained.

This application claims priority from Japanese Patent Application Nos. 2003-140347 and 2003-140348 (both filed on May 19, 2003), and the contents of these applications are incorporated herein by reference in this specification.

Claims (12)

1. eddy current type reduction gear comprises:

Be installed in the brake rotors on the rotation axis;

First magnet ring, it comprises that the circumferential compartment of terrain of annular magnet member and edge of relative arrangement with described brake rotors is embedded in a plurality of permanent magnets in the described magnetic component;

At second magnet ring of the relative arrangement with described first magnet ring of opposition side of described brake rotors, it comprises along circumferential spaced apart a plurality of permanent magnets; Wherein

Described first magnet ring is between described second magnet ring and described brake rotors;

The magnetic force of each permanent magnet of described second magnet ring is configured to greater than the total magnetic force that is used as at one or more permanent magnets of cooperation described first magnet ring partly of braking stopping period formation magnetic loop.

2. eddy current type reduction gear according to claim 1 is characterized in that:

The area of the pole surface of the permanent magnet of described second magnet ring is configured to equal form the gross area of pole surface of one or more permanent magnets of described first magnet ring of magnetic loop at described braking stopping period with the permanent magnet of described second magnet ring; And

The magnetic density of the permanent magnet of described second magnet ring is configured to the magnetic density greater than the permanent magnet of described first magnet ring.

3. eddy current type reduction gear according to claim 1 is characterized in that:

The magnetic density of the permanent magnet of the permanent magnet of described second magnet ring and described first magnet ring is configured to be equal to each other; And

The area of the pole surface of the permanent magnet of described second magnet ring is configured to greater than forming the gross area of pole surface of one or more permanent magnets of described first magnet ring of magnetic loop at described braking stopping period with the permanent magnet of described second magnet ring.

4. according to the arbitrary described eddy current type reduction gear of claim 1 to 3, it is characterized in that difference or the ratio long-pending based on magnetic force, magnetic density or pole surface between the permanent magnet of the permanent magnet of described first magnet ring and described second magnet ring are set in relative phase place between described first magnet ring of described braking stopping period and described second magnet ring.

5. eddy current type reduction gear comprises:

Be installed in the brake rotors on the rotation axis;

At the outer magnet ring of the relative arrangement with it in the inboard of described brake rotors, described outer magnet ring comprises a plurality of permanent magnets, and they are arranged at interval along circumferential, thereby have identical polarity along circumferential opposed facing magnetic pole;

At the inner magnet ring of the relative arrangement with it in the inboard of described outer magnet ring, described inner magnet ring comprises a plurality of permanent magnets, and their edges are circumferentially arranged at interval, thereby each magnetic pole edge of facing described outer magnet ring is circumferentially mutual opposite; Wherein, under the braking initiate mode, by making described outer magnet ring face mutually each other with designated phase with described inner magnet ring, be implemented between described outer and inner magnet ring and the described brake rotors and form magnetic loop, and under the braking halted state, by rotating described outer magnet ring and/or inner magnet ring from described braking initiate mode, be implemented in the magnetic loop that forms short circuit between described outer magnet ring and the described inner magnet ring through described designated phase; Wherein

The magnetic force of the permanent magnet of described inner magnet ring is configured to greater than forming the total magnetic force of one or more permanent magnets of described outer magnet ring of the cooperation part of magnetic loop as described braking stopping period with the permanent magnet of described inner magnet ring; And

The magnetic flux that leaks into described brake rotors under described braking halted state is zero.

6. eddy current type reduction gear according to claim 5 is characterized in that:

Described outer magnet ring comprises the annular magnet member, and described a plurality of permanent magnets are along circumferentially being embedded in the described magnetic component with constant space; And

Be formed on the radial outside of each permanent magnet by the thin layer portion of described magnetic component generation.

7. eddy current type reduction gear comprises:

Be installed in the brake rotors on the rotation axis;

First magnet ring of relative arrangement with described brake rotors, described first magnet ring comprise along circumferential spaced apart a plurality of permanent magnets, and described permanent magnet is along circumferentially having magnetic pole on the end surface of its both sides;

Second magnet ring of relative arrangement with described first magnet ring, described second magnet ring comprise along circumferential spaced apart a plurality of permanent magnets, and described permanent magnet is along circumferentially having magnetic pole on the end surface of its both sides; Wherein

Described first magnet ring is between described second magnet ring and described brake rotors;

The magnetic force of the magnet of described first magnet ring is set in 1 with the ratio of the magnetic force of the magnet of described second magnet ring: about 1.2 to about 1.6 scope.

8. eddy current type reduction gear according to claim 7 is characterized in that:

The magnetic force of the per unit surface area of the magnet of described first magnet ring and described second magnet ring is configured to mutually the same; And

The area of the pole surface of the magnet of described first magnet ring is set in 1 with the ratio of the area of the pole surface of the magnet of described second magnet ring: about 1.2 to about 1.6 scope.

9. according to claim 7 or 8 described eddy current type reduction gears, it is characterized in that:

The axial length of the magnet of described first magnet ring and described second magnet ring and circumferential lengths are set as respectively and are equal to each other; And

The radical length of the magnet of described first magnet ring is set in 1 with the ratio of the radical length of the magnet of described second magnet ring: about 1.2 to about 1.6 scope.

10. eddy current type reduction gear comprises:

Be installed in the brake rotors on the rotation axis;

At the outer magnet ring of the relative arrangement with it in the inboard of described brake rotors, described outer magnet ring comprises a plurality of permanent magnets, thereby described a plurality of permanent magnet is had identical magnetic along circumferential the layout at interval along circumferential opposed facing magnetic pole;

At the inner magnet ring of the relative arrangement with it in the inboard of described outer magnet ring, described inner magnet ring comprises a plurality of permanent magnets, thereby described a plurality of permanent magnet is had identical magnetic along circumferential the layout at interval along circumferential opposed facing magnetic pole; Wherein, under the braking initiate mode, by making described outer magnet ring face mutually each other with designated phase with described inner magnet ring, be implemented between described outer and inner magnet ring and the described brake rotors and form magnetic loop, and under the braking halted state, by rotating described outer magnet ring and/or inner magnet ring from described braking initiate mode, be implemented in the magnetic loop that forms short circuit between described outer magnet ring and the described inner magnet ring through described designated phase; Wherein

The magnetic force of the magnet of described outer magnet ring is set in 1 with the ratio of the magnetic force of the magnet of described inner magnet ring: about 1.2 to about 1.6 scope.

11. eddy current type reduction gear according to claim 10 is characterized in that:

Described outer magnet ring comprises the annular magnet member, and described a plurality of permanent magnets are along circumferentially being embedded in the described magnetic component with constant space; And

Be formed on the radial outside of each permanent magnet by the thin layer portion of described magnetic component generation.

12. eddy current type reduction gear according to claim 11 is characterized in that:

In the part that is placed in the described magnetic component between described each permanent magnet, be formed with radially outward outstanding jut.

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