JP3339251B2 - Dynamic damper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic damper for suppressing torsional vibration generated on a rotating shaft, for example, a crankshaft of an engine.

[0002]

2. Description of the Related Art An engine mounted on an automobile, for example, a reciprocating engine, performs each of intake, compression, explosion, and exhaust strokes in a cylinder in accordance with reciprocation of a piston. Vibration easily occurs on the crankshaft (rotary shaft).

[0003] The torsional vibration causes problems such as strength problems of the crankshaft and occurrence of a tapping noise with a bearing supporting the crankshaft. Therefore, conventionally, as a countermeasure for this, a dynamic damper called a torsion damper is provided at the tip of the crankshaft, for example, to reduce torsional vibration of the crankshaft and protect the crankshaft from torsional vibration. Reductions have been made.

In recent years, a dynamic damper called a triple mass damper has been used to further reduce torsional vibration. As shown in FIG. 6, the triple mass damper includes a plurality of annular inertia members b on elastic member (made of rubber) e to g on a side surface of a hub a fixed to a crankshaft (not shown). To d are fixed, and the first to the first are composed of an elastic body and an inertial body.
The third dampers h to j reduce the peak value of torsional vibration generated on the crankshaft.

That is, as shown by the broken line in FIG. 7, one high peak of the torsional vibration generated on the crankshaft when there is no damper is dispersed into a plurality as the damper is added to the crankshaft. It shows the behavior that the peak value decreases. Specifically, when the first to third dampers h to j are attached, as shown by the solid line, the peaks are dispersed into four peaks and flattened, and the peak value of the torsional vibration is considerably reduced. Note that the dashed line in FIG. 7 indicates the behavior of torsional vibration of the crankshaft when one damper is attached, and the two-dot chain line indicates the behavior of torsional vibration of the crankshaft when two dampers are attached. .

By the way, such a dynamic damper using a plurality of, ie, three, dampers h to j usually sets natural frequencies for a low frequency, a high frequency, and an intermediate frequency, respectively, in order to reduce torsional vibration. The peak is dispersed (at the same frequency, the peak of the torsional vibration does not disperse).

The setting of the natural frequency f of the damper is performed by using the following equation. f = 1 / 2π · (K / I) ^1/2 where K is a dynamic spring constant and I is a moment of inertia (mass of inertia).

According to the equation, in order to increase the natural frequency of the damper, the value of I (inertia mass) is reduced as shown in Japanese Patent Application Laid-Open No. 5-321981, and conversely, the natural frequency of the damper is reduced. To lower the number, the value of I (inertia mass) may be increased.

However, a satisfactory natural frequency cannot often be obtained only by this change. In such a case, I
In addition to changing the (inertia mass), the value of K (spring constant) of the rubber (elastic body) is also changed to set a plurality of necessary (high, middle, and low) natural frequencies. .

[0010]

However, if a soft rubber (elastic body) is adopted by changing the spring constant, the required natural frequency of the damper can be obtained, but the rubber is easily twisted ( Rubber distortion: large) behavior appears.

Particularly, a damper having a low natural frequency has a small spring constant and a large inertial mass, so that a very twistable behavior appears. This means that each damper h
As shown in FIG. 8, the torsional amplitudes of .about.j have such a characteristic that only the maximum value of the damper having a low natural frequency is considerably larger than the maximum values of the other dampers.

Therefore, during the rotation of the crankshaft, the damper which is easily twisted tends to generate a larger rubber distortion than the other dampers, and due to this burden, only a specific damper reaches the end of its life earlier than other dampers. Sometimes.

[0013] In this case, although the other dampers have a sufficient life, the entire dynamic damper may have to be replaced due to the life of the specific damper alone, and it is required to improve the durability life. ing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dynamic damper in which the durable life of each damper can be set to be almost the same.

[0015]

Means for Solving the Problems In order to achieve the above object, the invention described in the first aspect is characterized in that a hub fixed to a rotary shaft and three hubs having different inertial masses fixed to the hub via an elastic body. In the dynamic damper having an inertial body, the damper having the largest inertial mass and the damper having an intermediate inertial mass are fixed to the same side surface of the hub via elastic bodies, respectively, A damper having an inertial mass is fixed to an opposite side surface of the hub via an elastic body, and a fixing surface of the inertial mass and the elastic body is formed by extending an extending line of the fixing surface to a predetermined center axis of the hub. an angle intersecting the position, the with the value of the dynamic spring constant of the dampers is set within a range of 10% ±, dampers having the largest inertial mass and damper having an inertial mass of the intermediate Natural frequency ratio (fd ₂ / fd ₁₎ the natural frequency ratio of the damper having the largest inertial mass and damper having the smallest inertial mass and sets the 1.55~1.9 (fd ₃ / fd ₁ ) to 2.2-
It is set to 2.7. In addition to the above object, the invention according to claim 2 provides, in addition to the configuration of claim 1, the inertia of the damper provided on the same side surface of the hub in order to simplify the molding die for forming the dynamic damper. A rubber injection hole is provided at a position corresponding to the inertial body fixed to the side opposite to the body and the hub.

[0016]

[0017] According to the invention described in claim 1, the maximum value of the twist amplitude of each Dan <br/> pa, the homogenization of the rubber strain for each damper, without fluctuated as in the conventional large, uniform Will be done. Also, the peak of torsional vibration is at four peaks
It is dispersed and flattened.

For this reason , each damper is determined to have the same durable life without the trouble that the specific damper reaches the end of its life early. In addition , torsional vibration can be favorably damped with three dampers having a reduced outer diameter.

Furthermore, the three dampers have an equal distortion shape, which is assumed to be equally distorted, and are compactly assembled on both sides of the hub. Here, the equidistant shape requires only a minimum necessary dimension between the fixing surfaces of the elastic bodies on both sides of the hub.

Therefore, a compact dynamic damper can exhibit good vibration damping properties. According to the invention described in claim 2, only the mold for molding the respective elastic members of the dynamic damper is provided with a rubber injection unit on the side corresponding to the two inertial body located on the same surface, shaped elastic body The necessary injection path is secured. This means that the mold for forming the dynamic damper has a simple structure.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to one embodiment shown in FIGS. FIG. 1 shows an end portion of an engine, for example, a reciprocating engine. In the drawing, reference numeral 1 denotes a crankshaft (rotating shaft ) mounted on a cylinder block 2 of the engine.

At the end of the crankshaft 1 protruding from the cylinder block 2, a pulley 3 for belt driving an auxiliary machine such as an alternator (not shown) is mounted.

A dynamic damper 4 called a triple mass damper, which is a main part of the present invention, is provided on the front surface of the pulley 3 facing forward. Describing the dynamic damper 4, reference numeral 5 denotes a hub.

The hub 5 is formed of, for example, an annular plate 6 whose center is recessed toward the cylinder block 2. An annular mounting seat 7 formed at the center of the plate 6 is fixed to the front surface of the pulley 3 with bolts 8 to support the entire hub in a direction orthogonal to the axis of the crankshaft 1.

A plurality of, for example, three first to third dampers 9a to 9c are provided on a plate portion extending in the outer peripheral direction of the hub 5. Each of the first to third dampers 9a to 9c has a structure in which, for example, an annular inertial body 10 is fixed to the plate 6 via an elastic body 11 (made of rubber).
Two of the dampers 9a and 9b are concentrically fixed to the same side surface of the plate 6 facing the cylinder block 2, and the remaining damper 9c is arranged on the opposite side surface of the plate 6 with the small-diameter side damper 9b. It is fixed.

The first to third dampers 9a to 9c are set to have low, high, and intermediate natural frequencies, respectively. Specifically, the first to third dampers 9a to 9c are set to the respective natural frequencies as follows.

That is, the natural frequencies of the first to third dampers 9a to 9c are fd ₁ to fd _3, and the dampers 9a to 9c
Id ₁ the moment of inertia of ～Id ₃ and then, and a dynamic spring constant of the elastic body 10 of the damper 9a to 9c K ₁ ~K ₃
Where f = 1 / 2π · (K / I) ^1/2 where K is the dynamic spring constant and I is the moment of inertia (mass of inertia).

Fd ₁ <fd ₂ <fd ₃ , Id ₁ > Id ₂
> Id _3, so as to substantially each passage of the same value K ₁ ~K _3, the spring constant K, by changing the inertial mass, setting the natural frequency fd ₁ ~fd ₃ of the first to third dampers 9a~9c I have.

Utilizing this setting, the dynamic damper 4 connects the hub 5 with the damper 9a having a large inertial mass and the damper 9b having an intermediate inertial mass among the first to third dampers 9a to 9c having different inertial masses. And the damper 9c having the smallest remaining inertial mass is fixed to the opposite surface.

Further, as shown in FIG. 1, each of the fixed surfaces 12a to 12c to which both the inertial body 10 and the elastic body 11 are fixed has an extension line 13 extending from the fixed surfaces 12a to 12c. The angle θ intersects a predetermined position of the center axis of the hub. As a result, the thickness of each elastic body 11 is regulated to the minimum width so that each part is equally distorted, and the entire elastic body is formed into a shape in which unnecessary rubber distortion does not occur, that is, a so-called equal distortion shape.

The values of the dynamic spring constants K _{1 to} K ₃ of the _first to third dampers 9 a to 9 c are all within a range of approximately 10%, for example, K ₂ / K ₁ and K ₃ / K _1. Is 0.9 ~
The value is set to 1.1.

Using this setting, the maximum value of the torsional amplitude of each of the first to third dampers 9a to 9c is determined to be substantially the same. That is, according to the applicant, as shown in the diagram of FIG. 4, the dynamic spring constant ratio of each of the first to third dampers 9a to 9c and the torsional amplitude of each of the dampers 9a to 9c include the spring constant ratio. It has been confirmed that the amplitude increases at the point where the value becomes zero, and the present applicant makes use of this damper characteristic to set the maximum value of the torsional amplitude of each of the dampers 9a to 9c to be substantially the same. It is within the S range.

Using this setting, the first to third dampers 9a
To 9c, for example, fd ₂ / fd ₁ = 1.5
5 to 1.9, fd ₃ / fd ₁ = 2.2 to 2.7.

On the other hand, the first,
The inertia bodies 11 of the second dampers 9a and 9b are provided with a plurality of rubber injection holes 14 penetrating in the thickness direction at predetermined intervals as shown in FIG.

The rubber injection holes 14 are also formed at predetermined intervals in a plate portion of the hub 5 to which the inertial body 11 of the third damper 9c is fixed. These rubber injection holes 14 are through holes used when the dynamic damper 4 is formed by vulcanization.

The dynamic damper 4 uses the through holes to form the elastic body 11 while assembling each inertial body 11 to the plate 6 of the hub 5. In addition, each of the first to third
A large number of grooves 16 for forming the cooling fins 15 are formed on the inertial body side surfaces of the dampers 9a to 9c.

Next, the operation will be described. Along with the operation of the reciprocating engine, a large peak torsional vibration is generated on the crankshaft 1 due to a torque fluctuation or the like.

At this time, the dynamic damper 4 is rotated together with the crankshaft 1, and the peak of torsional vibration generated in the crankshaft 1 is dispersed into a plurality by the damping performed by the first to third dampers 9a to 9c. .

Specifically, the first to third dampers 9a to 9c
Are set for the low frequency, the intermediate frequency, and the high frequency, respectively, so that they are distributed over four peaks as shown in FIG. And is flattened.

[0040] Here, when setting the natural frequency fd ₁ ~fd ₃ of the first to third damper 9a to 9c, is that's conventional Determination, by changing the spring constant K ₁ ~K _3, is required although that natural frequency fd ₁ ~fd ₃ of the dampers 9a~9c is obtained, the damper, the first particular natural frequency is small
Since the elastic body 11 of the damper 9a is made of soft rubber that is easily twisted, a behavior in which rubber distortion is increased may appear.

According to the present invention, each of the first to third dampers 9a
~9c the value of the dynamic spring constant K ₁ ~K ₃ is are defined within a range of approximately ± 10%. This means that the natural frequency fd ₁
Setting the ～Fd ₃ to a predetermined frequency, the dampers 9a~
The maximum value of the torsional amplitude of 9c falls within a narrow range of S as shown in FIG.

According to the experiment, the first to third dampers 9a to 9
By setting the dynamic spring value constants K ₁ ~K ₃ of c in the range of about ± 10%, of the first to third dampers 9a~9c as shown in FIG. 5 twist amplitude (Rubber strain) The maximum value is equalized, and although not shown, the value outside the range is strongly affected by rubber distortion, and the maximum value of the torsional amplitude of a specific damper is
A characteristic was obtained which was considerably larger than the maximum value of the torsional amplitude of the other dampers.

Therefore, it is understood that the rubber strain is made uniform for each of the first to third dampers 9a to 9c by defining the dynamic spring constants K _{1 to} K ₃ . Therefore, each of the first to third dampers 9a to 9c of the dynamic damper 4 can solve the problem that the specific damper reaches the end of its life earlier as in the related art, that is, can be set to the same durable life.

Moreover, such dynamic spring constants K _{1 to} K ₃
In addition to the above, of the three first to third dampers 9a to 9c, the damper 9a having the largest inertial mass and the damper 9b having the intermediate inertial mass are fixed to the same surface of the hub 5,
A damper 9c having a damper 9c having the smallest inertial mass is fixed to a surface on the opposite side of the hub 5, and a fixed surface 12 between the inertial body 10 and the elastic body 11 is formed by an extension line 13 extending from the fixed surface 12. When the dynamic damper 4 having a structure of an angle crossing a predetermined position of the center axis of the hub 5 is adopted,
A compact dynamic damper 4 having good characteristics can be realized.

That is, the dynamic damper 4 is
With the structure of providing two on one side and one on the other side, which is a feature of the above, the torsional vibration can be effectively damped with a small number of dampers of three while suppressing the outer diameter.

In addition, each of the dampers 9a to 9c has the second characteristic, that is, the elastic body 1 having a uniform distortion shape which is assumed to be equally distorted.
1 and is incorporated on both sides of the hub 5. This equidistant shape is achieved by fixing surfaces 12, 12 on both sides sandwiching hub 5.
The distance between them is the minimum necessary.

As a result, the width of the dynamic damper 4 is suppressed. However, the compact dynamic damper 4 can exhibit good vibration damping performance.

In addition, rubber injection holes 14 are respectively formed in the plate portions of the hub 5 corresponding to the inertia bodies 11 of the dampers 9a and 9b on the same side surface of the hub 5 and the inertia body 11 of the damper 9c on the opposite side. With the structure provided, the dynamic damper 4
The molding dies 17a and 17b manufactured by the above can be manufactured with a simple structure.

That is, when the dynamic damper 4 is manufactured by vulcanization molding with the rubber injection hole 11 provided as described above, a pair of molding dies are formed as shown in FIGS. 17a and 17b, the hub 5 is housed, and the inertial bodies 11 of the dampers 9a, 9b are housed on one side so as to sandwich the plate 6 of the hub 5, and the damper 9c is housed on the other side.
After accommodating the inertial body 11, the elastic body 11 of each of the dampers 9a and 9b is vulcanized and molded by simply injecting the rubber material 18 from the rubber injecting portion 19a of the molding die 17b. Are fixed to the hub 5 via the elastic body 11.

That is, the rubber material 18 entering from the rubber injection portion 19a on the upper side is formed between the inertial body 11 and the plate 6 through the rubber injection port 14 on the inertia body 11 of the damper 9a. The elastic body 11 having a predetermined outer shape is filled in the molding space 20a. Also, the rubber material 18 entering from the rubber injection portion 19b on the lower side passes through the molding space 20b formed on the back surface side of the inertial body 11 of the damper 9b and the rubber injection port 14 on the hub 5 to form the damper 9c. Filling the molding space 20c formed between the inertial body 11 and the plate 6,
0c, the elastic body 11 having a predetermined outer shape is molded, and the molding space 20b formed between the inertial body 11 of the damper 9b and the plate 6 is filled to form the same molding space 2b.
At 0b, the elastic body 11 having a predetermined outer shape is formed.

This means that the molding dies 17a and 17b have a simple structure in which the rubber injection portions 19a and 19b are provided only on one side, so that the injection paths required for molding each elastic body 11 can be secured. become.

In addition, due to the injection of the rubber material 18 from one side, the plate 6 is kept in the molding space 17a during molding.
In addition, since it is always pressed against the mold 17b, there is also an effect that bending due to the vulcanization pressure can be reduced.

Although the present invention has been applied to a reciprocating engine, the invention is not limited to this, and it goes without saying that the present invention may be applied to a dynamic damper mounted on a rotating shaft of another engine or another rotating device. Absent.

Needless to say, the present invention relates to the third embodiment described above.
The present invention is not limited to a dynamic damper having one damper, and may be applied to a dynamic damper having more dampers.

[0055]

As described above, according to the first aspect of the present invention, the maximum value of the torsional amplitude of each damper can be set to a large value unlike the prior art by making the rubber strain uniform for each damper. , Can be made uniform. Also torsional vibration
Are dispersed in four peaks and flattened.

As a result, the durability life of each damper can be determined to be almost the same. In addition , the outer diameter has been reduced and the distance between the fixed surfaces of the inertial body sandwiching the hub has been minimized.
It is possible to realize a dynamic damper that is compact and can exhibit good vibration damping performance.

According to the second aspect of the present invention, the above-mentioned claim is provided.
In addition to the effects of the first aspect of the present invention, a molding die for molding each elastic body of the dynamic damper is required. Since it is only necessary to provide a rubber injection portion on the side corresponding to the two inertial bodies on the same surface, a molding die for molding a dynamic damper can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a dynamic damper according to an embodiment of the present invention, together with a tip portion of a crankshaft to which the damper is mounted.

FIG. 2 is a side view of the dynamic damper viewed from a direction A in FIG.

FIG. 3A is a diagram for explaining an initial step when a dynamic damper is manufactured. (B) is a sectional view for explaining a step of injecting a rubber material into a molding die, forming an elastic body, and fixing the inertial body to the hub via the elastic body.

FIG. 4 is a diagram showing a relationship between a dynamic spring constant of a damper and a torsional amplitude of the damper.

FIG. 5 is a diagram for explaining that the maximum values of the torsional amplitudes of a plurality of dampers are set uniformly by the definition of the dynamic spring constant of the dampers.

FIG. 6 is a cross-sectional view showing a dynamic damper using three inertial bodies used in a conventional engine.

FIG. 7 is a diagram for explaining that torsional vibration generated on a crankshaft is dispersed by a dynamic damper.

FIG. 8 is a diagram for explaining the degree of torsional amplitude of each damper constituting the dynamic damper.

[Explanation of symbols]

1 ... crankshaft (rotary axis) 3 ... pulley 4 ...
Dynamic damper 5 ... Hub 6 ... Plate 7 ...
Mounting seats 9a to 9c Damper 10 Inertial body 11
... elastic bodies 12a to 12c ... fixed surface 14 ... rubber injection holes.

Continuation of the front page (56) References JP-A-6-241281 (JP, A) Japanese Utility Model Application No. Sho 59-163250 (JP, U) Japanese Utility Model Application No. Sho 59-163248 (JP, U) Japanese Utility Model Application No. Sho 57-202036 (JP, U.S.A.) , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 15/126 F02B 77/00

Claims (2)

(57) [Claims] 1. A dynamic damper comprising a hub fixed to a rotating shaft and three inertia bodies having different inertia masses fixed to the hub via an elastic body, wherein a largest one of the inertia masses is provided. And a damper having an intermediate inertial mass is fixed to the same side surface of the hub via an elastic body, and a damper having the smallest inertial mass is fixed to the opposite side surface of the hub via an elastic body. And the fixed surface of the inertial mass and the elastic body forms an angle at which an extension of the fixed surface intersects a predetermined position of the center axis of the hub, and the value of the dynamic spring constant of each of the dampers is ± 10. %, And the natural frequency ratio (fd ₂ / fd ₁ ) between the damper having the intermediate inertial mass and the damper having the largest inertial mass is set to 1.55 to 1.9. When Natural frequency ratio of the damper having the largest inertial mass and damper having the smallest inertial mass (fd
₃ / fd ₁ ) is set to 2.2 to 2.7. 2. A rubber injection hole is provided at a position corresponding to each inertial body of the damper provided on the same side surface of the hub and an inertial body fixed to the side surface opposite to the hub. The dynamic damper according to claim 1, wherein: