WO2010008103A1

WO2010008103A1 - Continuously variable transmission

Info

Publication number: WO2010008103A1
Application number: PCT/KR2008/004152
Authority: WO
Inventors: Chong-Ki Kim
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-07-15
Filing date: 2008-07-15
Publication date: 2010-01-21
Anticipated expiration: 2011-01-15

Abstract

The present invention relates generally to a continuously variable transmission comprising a driving shaft (1); a variable crank (10) operationally coupled to the driving shaft (1); a housing (20) into which the variable crank (10) is rotatably inserted and which accommodates a moving guide (21) and a slide joint (22); a main body (30) provided with at least four fixed cranks (31) that are radially distributed at regular angles with a predetermined distance away from the center, each having a slide bar (33), and at least four power transfer means(32) connected at the opposite sides of the fixed cranks (31), respectively; and a driven shaft (2) inserted into the main body (30) and operating in engagement with the power transfer means (32), wherein the fixed cranks (31) execute a sequential continuous constant-speed rotational movement according to the rotation of the variable crank (10), while varying angular displacement thereof in proportion to an eccentricity(Rl) of the variable crank (10).

Description

Description CONTINUOUSLY VARIABLE TRANSMISSION

Technical Field

[1] The present invention relates generally to a continuously variable transmission using a variable crank, a moving guide, fixed cranks, etc. In particular, the present invention relates to a continuously variable transmission where the moving guide is connected to the variable crank that is connected to a driving shaft, at least four fixed cranks are arranged in slidable contact with the moving guide to move (or slidably move), and a split rotational force is transmitted to a driven shaft at constant speed by means of a c connected to those fixed cranks. Background Art

[2] A continuously variable transmission (CVT) is known as a high efficiency power transfer device as compared with existing transmissions, so great efforts have been put into the commercialization of the CVTs. One of typical examples of commercialized CVTs at present is a variable pulley -belt type CVT, and ongoing studies on a toroidal type CVT using metal rollers and laces, a hydro-mechanical type CVT, or a CVT with a planetary gear are under progress.

[3] However, the variable pulley-belt type CVT cannot be fully substituted for a conventional manual transmission and an automatic transmission in many fields because it is difficult to transmit a large driving power, an additional device is required to get accelerations for example, and its transmission ratio range is not large.

[4] Meanwhile, to overcome the limitations of the CVT as noted above, a method has been suggested in Korea Patent Application Laid-open No. 2006-38324 that a rotational force of a driving shaft or a variable crank should be split to a rotational force for four driven shafts and these four split rotational forces are added together again by using a power transfer means and a bevel gear assembly. This CVT has a relatively simple structure, so it is easy to achieve a mechanical continuous transmission, and to transmit a large driving power at a small loss in the power. Disclosure of Invention

Technical Problem

[5] However, the CVT of the patent document aforementioned has a shortcoming that there are some differences in rotational speed of each driven shaft which rotates along with the variable crank. Such differences in speed consequently impede smooth rotation which is essential for a transmission, such that vibrations occur and components are mechanically burdened, thereby leading to deterioration in efficiency and durability. [6] To resolve the foregoing problem(s) of the CVT, the present invention is directed to a continuously variable transmission featuring smooth rotation, which is capable of transmitting a rotational force at constant speed in use of a variable crank, a moving guide, and at least four fixed cranks.

Advantageous Effects

[7] The CVT of the present invention has a relatively simple structure for facilitating automatic mechanical continuous transmission, transfers a large driving power, and has low power loss. Moreover, the CVT of the present invention offers practical advantages, in terms of compact design, durability, and limitless transmission range. Particularly, as the CVT of the present invention transmits a rotational force at constant speed without variations, it operates or runs very smoothly.

Brief Description of Drawings

[8] The above and other objects and features of the present invention will become apparent from the following description of the preferred embodiments given in reference to the accompanying drawings, in which:

[9] Fig. 1 is a schematic front view showing the entire configuration of a continuously variable transmission (CVT) in accordance with the present invention;

[10] Fig. 2 a cutaway view used to explain the operating principles of a CVT in accordance with the present invention;

[11] Fig. 3 illustrates positional relations of elements used to explain the operating principles of a CVT in accordance with the present invention;

[12] Fig. 4 is a schematic perspective view of a slide joint and a moving guide of a CVT in accordance with a preferred embodiment of the present invention;

[13] Fig. 5 is a left side elevation view of a housing and a moving guide of a CVT in accordance with a preferred embodiment of the present invention, as seen from a driven shaft;

[14] Fig. 6 is a side elevation view of a main body of a CVT in accordance with a preferred embodiment of the present invention, as seen from a driving shaft;

[15] Fig. 7 is a side elevation view of a main body of a CVT in accordance with a preferred embodiment of the present invention, as seen from a driven shaft; and

[16] Fig. 8 illustrates overlapped rotation of fixed cranks of a CVT in accordance with a preferred embodiment of the present invention. Best Mode for Carrying out the Invention

[17] The present invention will now be explained in further detail with reference to accompanying drawings. Fig. 1 and Fig. 2 will be used first to explain the overall configuration of the present invention.

[18] A main part of the present invention includes a driving shaft 1; a variable crank 10 operationally coupled to the driving shaft 1 ; a housing 20 into which the variable crank 10 is rotatably inserted and which accommodates a moving guide 21 and a slide joint 22 (see Fig. 4); a main body 30 provided with at least four fixed cranks 31 that are radially distributed at regular angles with a predetermined distance away from the center, each having a slide bar 33, and at least four power transfer means 32 (see Fig. 7) connected at the opposite sides of the fixed cranks 31, respectively; and a driven shaft 2 inserted into the main body 30 and operating in engagement with the power transfer means 32.

[19] The variable crank 10 may come into diverse shapes or diverse systems to have variable eccentricity. For example, as long as part of the crank, that is, a variable portion 11 (see Fig. 5), can be moved from the shaft center line of the driving shaft 1 towards the edge, any elastic means such as spring or any shifting means such as cam unit or hydraulic means can be installed for moving the variable portion in the present invention. The motion of the variable portion 11 can also be controlled automatically according to the running speed, as well as the adjustment of variable quantity in manual mode. Examples of such a variable crank 10 are illustrated in the patent document (Korean Patent Application Publication No. 2006-38324) as before- mentioned.

[20] Moreover, the variable crank 10 may be coupled to the driving shaft 1 by the separate medium of a power transfer member such as a gear, or may be integrated with the driving shaft 1 as one body.

[21] One requirement condition the variable crank 10 of the present invention should satisfy is that eccentricity Rl of the variable crank 10 should not be larger than eccentricity R2 of the fixed cranks 31 (to be described), that is, Rl ? R2.

[22] For coupling between the housing 20 and the main body 30, the moving guide 21 of the housing 20 has concave type guide grooves on one side thereof, each guide groove receiving each slide bar 33 of the fixed cranks 31 on the same side. Also, the moving guide 21 has a pair of slides 23b (see Fig. 4) on the other side thereof. In Fig. 2 (or in Fig. 6), only the moving guide 21 of the housing 20 is represented in dotted lines as being schematically coupled to the main body 30.

[23] Fig. 4 is a schematic perspective view of a structure of the slide joint 22 of the CVT in accordance with a preferred embodiment of the present invention. As shown, the slide joint 22 includes a first plate 22a composed of one side which is provided with a pair of slides 23a and the other side which is affixed to the housing 20 as one body, and a second plate 22b composed of one side which is provided with a pair of first grooves 24a corresponding to the slides 23a of the first plate and the other side which is provided with a pair of second grooves 24b in a perpendicular orientation about the first grooves 24a. The second grooves 24b of the second plate 22b receive the slide pair 23b formed on the rear side of the moving guide 21. Therefore, with the thusly configured slide joint 22, the moving guide 21 can smoothly slide in horizontal and vertical directions. As evident in Fig. 3 (to be explained), the moving guide 21 shifts around in horizontal and vertical directions about the body 30, according to the eccentricity and rotation of the variable crank 10.

[24] Meanwhile, a uni-direction clutch is preferably used for the power transfer means 32.

However, the present invention is not limited thereto, but a variety of power connection/cutoff devices or a power transfer means such as bi-directional clutch can also be used. Besides, a gear is formed on the outer peripheral face of this power transfer means 32 to be in engagement with a gear of the driven shaft 2 (see Fig. 7).

[25] The following will now explain the operating principles on the power transfer and the transmission of the CVT in accordance with the present invention.

[26] Fig. 3(a) illustrates that when the eccentricity Rl of the variable crank 10 is "0", all of the center of the moving guide 21 and the slide joint 22 (not shown in Fig. 3) and the rotation axis and the eccentric axis of the variable crank 10 coincide with the center of the main body 30, and fixed cranks 31: 31a, 31b, 31c, and 3 Id are distributed in such a manner that the guide groove direction of the square moving guide 21 is in parallel with the eccentric direction of the fixed cranks 31. With the help of the slide joint 22, the moving guide 21 can translate in any arbitrary direction (both horizontally and vertically) about the main body 30, with no change in the direction on a plane, but cannot rotate.

[27] Here, the direction in which eccentricity varies is set to a reference angle (0 degree) at the time of rotation of the variable crank 10. Also, the fixed crank 31 indicates a crank having a fixed, non-variable eccentricity, as it is given with a predetermined eccentricity R2, so it should be understood as an opposite situation to the variable crank.

[28] If the eccentricity Rl of the variable crank 10 is set equal to the eccentricity R2 of the fixed cranks 31, say, lcm, the eccentricity of the variable crank 10 deviates from the center so that the moving guide 21 translates as much as lcm and the fixed cranks 31 inserted into the groove guides of the moving guide 21 are distributed as shown in Fig. 3(c) along with the planar motion of the moving guide 21. A close look at Fig. 3(c) also tells that the moving guide 21 moved upward in the drawing by a certain distance.

[29] In the state shown in Fig. 3(c), if the variable crank 10 rotates 90 degrees clockwise from 0 degree, the fixing crank 31a rotates 90 degrees counterclockwise (since R1=R2) at constant speed, while the fixed crank 31c that is positioned on the opposite side of a diagonal line rotates 90 degrees clockwise at constant speed. As depicted in Fig. 3(c), the fixed cranks 31a and 31c start rotating when the extension line in the eccentric direction of the variable crank 10 is at a 45 degree angle with the extension line of the grooves to which the fixed cranks 31a and 31c are guided, and their constant-speed rotation according to the eccentricity Rl of the variable crank 10 do not appear until the variable crank 10 rotates 90 degrees clockwise. In the meantime, the fixed crank 31b decelerates clockwise and eventually stops (speed = 0) when the variable crank 10 rotates 45 degrees. Then, when the variable crank 10 rotates up to 90 degrees, the fixed crank 31b switches its direction and accelerates counterclockwise from speed "0" to the constant rotation speed of the fixed crank 31a. Meanwhile, the fixed crank 3 Id located diagonally opposite the fixed crank 31b decelerates counterclockwise, contrary to the fixed crank 31b, and eventually stops (speed = 0) when the variable crank 10 rotates 45 degrees. Then, when the variable crank 10 rotates up to 90 degrees, the fixed crank 3 Id switches its direction and accelerates clockwise from speed "0" to the constant rotational speed of the fixed crank 31c. In short, the fixed cranks are distributed as shown in Fig. 3(d).

[30] Next, when the variable crank 10 rotates further from 90 degrees to 180 degrees, the fixed crank 31b rotates counterclockwise with constant speed by 90 degrees, the fixed crank 3 Id rotates clockwise with constant speed by 90 degrees, the fixed crank 31a switches its rotation direction from counterclockwise to clockwise, and the fixed crank 31c switches its rotation direction from clockwise to counterclockwise, respectively. In short, the fixed cranks are distributed as shown in Fig. 3(e).

[31] Next, when the variable crank 10 rotates further from 180 degrees to 270 degrees, the fixed crank 31c rotates counterclockwise with constant speed, the fixed crank 31a rotates clockwise with constant speed, the fixed crank 31b switches its rotation direction from counterclockwise to clockwise, and the fixed crank 3 Id switches its rotation direction from clockwise to counterclockwise, respectively. In short, the fixed cranks are distributed as shown in Fig. 3(f).

[32] Lastly, when the variable crank 10 rotates further from 270 degrees to 360 degrees, the fixed crank 3 Id rotates counterclockwise with constant speed, the fixed crank 31b rotates clockwise with constant speed, the fixed crank 31a switches its rotation direction from clockwise to counterclockwise, and the fixed crank 31c switches its rotation direction from counterclockwise to clockwise, respectively. In short, the fixed cranks are distributed as shown in Fig. 3(g).

[33] The rotation direction and (constant) speed movement of each of the fixed cranks 31 at the time of the 360-degree rotation of the variable crank 10 can be summarized as follows.

[34]

[35] Table 1 [Table 1] [Table ]

[36] [37] As such, when the variable crank 10 makes a 360-degree rotation with 90 degrees rotation each time, all of the fixed cranks 31 also run at a repetitive motion cycle such as constant speed rotation -> direction switch -> constant speed rotation -> direction switch -> constant speed rotation .... What comes next is to change this sequential and interrupted constant-speed rotation observed in those fixed cranks 31 into a continuous rotational movement through an arbitrary power transfer means.

[38] For example, it is possible to make the driven shaft 2 rotate by connecting a power transfer means, e.g., a uni-directional clutch, as a power transfer means to the fixed cranks 31. That is to say, the direction of the power transfer means 32 can be fixed in order to create only the "constant-speed rotational movement in a counterclockwise direction". In doing so, the gear (see Fig. 7) of the driven shaft 2 continuously rotates clockwise in engagement with the gear of the power transfer means 32.

[39] Suppose that the gear of the power transfer means 32 and the gear of the driven shaft 2 are at a gear ratio of 2: 1, and that both the eccentricity Rl of the variable crank 10 and the eccentricity R2 of the fixed cranks 31 equal to lcm. Even if those four fixed cranks 31 may execute a sequential, 90-degree rotational movement with constant speed at a time during one rotation of the variable crank 10, because only the counter- clockwise constant- speed rotational movement is selected by the power transfer means 32 and its gear, and transferred to the gear(s) of the driven shaft 2, a continuous rotation is achieved and thus, the driven shaft 2 rotates twice faster than the driving shaft 1.

[40] Further, if the eccentricity Rl of the variable crank 10 is reduced to 0.5cm, all of the fixed cranks 31 are re-arranged as illustrated in Fig. 3(b). And when the variable crank 10 rotates 360 degrees, each of the fixed cranks 31 transfers, through the medium of the power transfer means 32 and its gear, a constant-speed rotation force in result of the sequential, 45-degree rotation with constant speed in the counterclockwise direction to the gear(s) of the driven shaft 2, thereby causing it to rotate clockwise around one full circle. At this time, because the driven shaft makes one rotation when the driving shaft 1 makes one rotation, a transmission ratio is 1:1.

[41] In addition, if the eccentricity Rl of the variable crank 10 is reduced to "0" and the variable crank 10 is caused to make 360-degree rotation, since Rl = 0, the moving guide 21 would not move, the slide joint 22 would not slide, and the slide bars 33 of the fixed cranks 31 housed in the moving guide 21 would not move either. Consequently, the speed of the driven shaft 2 becomes "0". In other words, in case of making the driven shaft 2 go through continuously variable transmission by fixating the main body 30 and rotating the variable crank 10, the eccentricity Rl of the variable crank 10 increases up to a maximum speed which is equal to the eccentricity R2 of the fixed cranks 31. Then, the speed of the driven shaft 2 is finally determined by a gear ratio between the number of teeth of the gear of the power transfer means 32 and the number of teeth of the gear of the driven shaft 2.

[42] Meanwhile, suppose that the gear of the power transfer means 32 and the gear of the driven shaft 2 are at a gear ratio of 1 : 1. The speed range (or transmission range) of the driven shaft 2 is determined as 0 to 1 (this corresponds to the speed of the driving shaft), and undergoes continuously variable transmission proportionally to the eccentricity Rl of the variable crank 10.

[43] Alternatively, if a uni-directional clutch is used as a means for transferring the rotational force of the fixed cranks 31 to the driven shaft 2, the key requirement of the transmission (i.e., power transfer capability in both directions) could not be satisfied, only leading to deterioration in efficacy. Meanwhile, in order to transfer the rotational force of the fixed cranks 31 to the driven shaft 2 and to transfer the rotational force of the driven shaft 2 to the fixed cranks 31, a bi-directional power transfer means such as a single disk clutch or friction clutch should be used. However, as learned from the Table 1 provided earlier, the constant-speed rotational movement of each of the fixed cranks 31 is executed sequentially by fixed crank 31. In order to connect these divided, constant-speed rotational movements to a continuous constant- speed rotational movement, the rotational forces must be connected and cut at the same time within an extremely limited period of time between each of the fixed cranks 31 and its corresponding gear on the opposite side, thereby achieving a perfect continuous rotational movement for the driven shaft 2. In the case of a CVT provided with a square moving guide 21 and four fixed cranks 31, however, it may be difficult to use a mechanical means such as a friction clutch as a power transfer means between the fixed cranks 31 and a target gear.

[44] To resolve the aforementioned problems, a bi-directional power transfer means is adapted to a CVT in accordance with a preferred embodiment of the present invention. More details on such a CVT are as follows.

[45] Fig. 5 through Fig. 8 illustrate different components of a CVT in accordance with a preferred embodiment of the present invention. As shown in these drawings, a CVT of this embodiment is mostly similar in structure and its operating principles to the structure discussed earlier, except that a regular pentagonal shaped moving guide 21 is installed in a housing 20 and there are five fixed cranks 31 and five power transfer means 32 connected to the fixed cranks 31.

[46] In an actual operation, a variable crank 10 is fixated by the medium of a separate power transfer member, and a driving force from an engine is transferred to a housing 20 or a main body 30, so as to rotate the housing 20 or the main body 30. In the interest of brevity, the engine, the separate power transfer member, fixtures such as screws for interconnecting other components, etc., are not shown.

[47] In addition to the structure similarity, the power transfer and transmission procedures of the CVT of this embodiment are similar to those described earlier. First, as the housing 20 rotates by a driving force from the engine, and a driving shaft 1 or the variable crank 10 rotate relatively. With an increasing eccentricity Rl of the variable crank 10, slide bars 33 and fixed cranks 31 start to rotate according to the motion of the moving guide 21 of the housing 20 that is engaged with it. Next, the sequential rotation of the fixed cranks 31 causes the power transfer means 32, each having a gear on the outer peripheral face opposite to each of the fixed cranks 31, to rotate sequentially, and therefore gear(s) of a driven shaft 2 in engagement with the power transfer means 32 start rotating.

[48] As noted above, the CVT of this embodiment is provided with five fixed cranks 31 and the regular pentagonal shaped moving guide 21, and each fixed crank 31 executes a constant rotational movement during the 90-degree rotational movement (relatively) of the variable crank 10. Hence, during a 360-degree rotation of the variable crank 10, a sequential, divided constant- speed rotational movement appears five times, yet the constant rotation is overlapped by 18 degrees at five locations (see Fig. 8). Because there is sufficient spare time for actuating the power transfer means such as a bi- directional clutch particularly in those locations where the constant rotation is overlapped, a perfect continuous constant- speed rotational movement can be achieved. From this, one can easily guess that if a CVT is provided with six fixed cranks 31 and six regular hexagonal shaped mobbing guides 21, the constant- speed rotational movement would be overlapped by 30 degrees at six locations.

[49] Referring to Fig. 8, between the 72 degree angle where the constant rotational movement of the second fixed crank 31 starts and the 90 degree angle where the constant rotational movement of the first fixed crank 31 ends, a rotational force of the second fixed crank 31 may be transferred, by the medium of a second power transfer means 32 opposite to the second fixed crank 31 which starts the constant- speed rotational movement, to a gear at the outer peripheral face of the second power transfer means 32, and then a rotational force between the first fixed crank 31 and its corresponding gear of the first power transfer means 32 can be cut off. Further, when the variable crank 10 rotates to 90 degrees (i.e., practically the housing 20 or the main body 30 rotates 90 degrees counterclockwise), the rotational movement of the first fixed crank 31 is terminated. Next, when the variable crank 10 rotates further up to 144 degrees, the constant-speed rotational movement of the third fixed crank 31 starts, and a rotational force is transferred based on the method described before. Because there is sufficient spare time for connecting and cutting off the transfer of a rotational force between the fixe cranks 31 and its gear by the power transfer means in any location where the constant rotation is overlapped, a perfect continuous constant-speed rotational movement is transferred to the gear(s) of the driven shaft 2.

[50] To explain about the rotation of the main body 30 and the transmission ratio of the driven shaft 2, a gear ratio between the gear of the power transfer means 32 and the gear of the driven shaft 2 is set to 1.2: 1, both the eccentricity Rl of the variable crank 10 and the eccentricity R2 of the fixed cranks 31 are equal to lcm for example so as to fixate the variable crank and to rotate the main body 30 counterclockwise, and the power transfer means transfers only the counterclockwise rotational movement of the fixed cranks 31 to the driven shaft 2. Since R1=R2, the gear of the power transfer means 32 rotates together with the main body 30, rotating counterclockwise once during one rotation of the main body 30. Suppose that the gear of the power transfer means 32 has a total of 12 teeth, while the gear of the driven shaft 2 has a total of 10 teeth. Then, the gear of the driven shaft 2 rotates reversely in a clockwise direction by two teeth.

[51] For example, when the gear ratio is 1:1, the driven shaft 2 does not rotate. That is, if the gear of the power transfer means 32 is controlled to rotate by 10 teeth after reducing the eccentricity of the variable crank 10, the gear of the driven shaft 2 does not rotate. Next, when the eccentricity Rl of the variable crank 10 is set to "0" and the main body 30 is caused to rotate, the gear of the power transfer means 32 does not rotate but rotates only together with the main body 30 in engagement with the gear of the driven shaft 2, thereby achieving the transmission ratio of 1:1.

[52] When a continuously variable transmission is executed while the variable crank 10 is being fixated and the main body 30 is rotating, the power transfer 32 side is large as compared to the driven shaft 2 side in terms of gear ratio. When the eccentricity of the variable crank 10 is set to a maximum (which equals to the eccentricity of the fixed cranks), the driven shaft 2 rotates reversely in proportion to the gear ratio. Next, when the eccentricity Rl of the variable crank 10 is reduced in some measure, the reverse rotation of the driven shaft 2 slowly stops until the speed becomes "0". If the eccentricity is reduced even more, the driven shaft 2 rotates forward and its rotation speed increases. When the eccentricity Rl is "0", the driven shaft 2 rotates together with the main body 30, thereby achieving a transmission ratio of 1:1. In short, the smaller the eccentricity is, the faster the driven shaft 2 rotates forward.

[53] When applied to an automobile, the CVT in accordance with the present invention can reduce vibrations during high-speed driving and inertial energy loss in the fixed cranks for example, thereby improving the efficiency. In addition, without the use of a separate propulsion conversion mechanism, going between "Drive", "Neutral" and "Reverse" can be achieved simply by adjusting the eccentricity Rl, such that the overall structure can be simplified.

[54] While the present invention illustrated the moving guide 21 having a square shape or a regular pentagonal shape, its guide grooves can be formed in circular shape. In that case even if the constant-speed performance may be impaired, the slide joint 22 is no longer required. Also, in order to reduce weight, corners of the square or the pentagonal shape moving guide 21 may be eliminated, and only a portion of each fixed crank 31 to which the slide bar 33 is guided can be formed.

[55] While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

[56]

Claims

[1] A continuously variable transmission, comprising: a driving shaft (1); a variable crank (10) operationally coupled to the driving shaft (1); a housing (20) into which the variable crank (10) is rotatably inserted and which accommodates a moving guide (21) and a slide joint (22); a main body (30) provided with at least four fixed cranks (31) that are radially distributed at regular angles with a predetermined distance away from the center, each having a slide bar (33), and at least four power transfer means(32) connected at the opposite sides of the fixed cranks (31), respectively; and a driven shaft (2) inserted into the main body (30) and operating in engagement with the power transfer means (32), wherein the fixed cranks (31) execute a sequential continuous constant-speed rotational movement according to the rotation of the variable crank (10), while varying angular displacement thereof in proportion to an eccentricity(Rl) of the variable crank (10).

[2] The continuously variable transmission of claim 1, wherein the eccentricity (Rl) of the variable crank (10) is adjusted to be smaller than or equal to an eccentricity of the fixed cranks (31).

[3] The continuously variable transmission of claim 1 or claim 2, wherein a gear of the power transfer means (32) connected to the fixed cranks (31) has a larger number of teeth than a gear of the driven shaft (2) in an engagement position thereof.

[4] The continuously variable transmission of claim 1, wherein the variable crank

(10) is fixated and a driving force from an engine is transferred to the housing (20) or to the main body (30), so as to make the housing (20) or the main body (30) rotate.