JP7391106B2 - transmission - Google Patents

Description

The present invention relates to a transmission.

A first gear arranged on the shaft and having first teeth on the end face in the axial direction, and a gear stage higher than the gear stage constituted by the first gear, and arranged on the shaft and having second teeth on the end face in the axial direction. A transmission is known that includes a second gear provided and a shift device that selectively couples the first gear and the second gear to a shaft. The transmission disclosed in Patent Document 1 includes an annular first hub and a second hub that are coupled to a shaft, and an annular hub that is arranged on the outer periphery of the first hub and that is rotatably engageable with the first hub and that is axially engaged with the first hub. a first ring that is movable; and a second ring that is arranged around the outer periphery of the second hub and that is rotatably engageable with the second hub and movable in the axial direction, the first ring meshing with the first teeth; Dog teeth are provided on the axial end surface of the first ring, and second dog teeth that mesh with the second teeth are provided on the axial end surface of the second ring.

In this transmission, when the first dog tooth meshes with the first tooth and the second dog tooth meshes with the second tooth when switching from a low gear stage driven by the first gear to a high gear stage driven by the second gear, the second dog tooth meshes with the second tooth. , the engagement between the first tooth of the first gear, which rotates slower than the second gear, and the first dog tooth of the first ring is released, and at the same time, the engagement between the first tooth and the first dog tooth is released. The first ring is slid in the direction by the elastic force of the spring. This makes it possible to achieve a so-called seamless shift, which is a shift that suppresses interruptions in the driving torque.

Patent No. 6438292

However, in the technique of Patent Document 1, double meshing in which the first dog tooth meshes with the first tooth and the second dog tooth meshes with the second tooth does not occur, so the meshing between the first tooth and the first dog tooth does not occur. When releasing the first ring, it is not possible to slide the first ring using the circulating torque generated by the double engagement. Since the first ring must be slid only by the elastic force of the spring, there is a problem in that a spring with a large elastic force must be used to overcome the friction between the first hub and the first ring. If a spring with a large elastic force is used, the space required for the spring to be displaced becomes large, and the force applied to the spring to obtain the large elastic force becomes large, resulting in poor assemblage.

Further, in order to mesh the second dog tooth with the second tooth when the first dog tooth is meshed with the first tooth, it is necessary to increase the backlash between the second tooth and the second dog tooth. However, if the backlash is increased, there is a problem in that impact noise is likely to occur when tooth surfaces hit each other during torque transmission.

The present invention has been made to solve this problem, and an object of the present invention is to provide a transmission that can achieve seamless shifting while suppressing noise and the elastic force required for the spring.

In order to achieve this object, the transmission of the present invention includes a first gear that is arranged on a shaft and constitutes a predetermined gear stage and has first teeth on an end face in the axial direction, and a gear stage that the first gear constitutes. a second gear that constitutes a higher gear stage and is arranged on the shaft and has second teeth on the end surface in the axial direction; and a shift device that selectively couples the first gear and the second gear to the shaft. , the shift device includes an annular first hub and a second hub coupled to the shaft, and is arranged on the outer periphery of the first hub and is rotatably engageable and axially movable with respect to the first hub. a first ring having a first dog tooth provided on an axial end surface thereof that engages with the first tooth; and a first ring disposed on the outer periphery of a second hub and capable of engaging with the second hub in the rotational direction and movable in the axial direction. a second ring having second dog teeth provided on an axial end surface thereof and meshing with the second teeth; a first fork attached to the first ring; a second fork attached to the second ring; and a first cam. a shift drum in which a groove and a second cam groove are formed, and a first rod in which a first engaging portion that engages with the first cam groove is disposed and moves the first fork in the axial direction along the first cam groove. and a second rod in which a second engaging portion that engages with the second cam groove is disposed and moves the second fork in the axial direction along the second cam groove, and the shift drum is configured to move the second fork in the axial direction along the second cam groove. and a neutral region in which the second rod is set to a neutral position, and the axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the meshing of the first dog tooth meshes with the first tooth. a release region that sets the axial position of the first rod so as to release the first rod; the shift device is interposed between the first rod and the first fork, and in the release region, the first fork is moved by an elastic force. It includes a spring that biases in the axial direction, and a thrust generating section that applies an axial thrust to the first ring that separates the first dog tooth and the first tooth in the release region, separately from the elastic force of the spring. There is.

According to the transmission according to claim 1, the axial position of the second rod is set by the release area of the shift drum so that the second dog tooth meshes with the second tooth, and the first dog tooth meshes with the first tooth. The axial position of the first rod is set to disengage the teeth. A spring interposed between the first rod and the first fork biases the first fork in the axial direction with elastic force in the release region. The thrust generating section generates a release area separately from the elastic force of the spring by utilizing the circulating torque generated by the double meshing in which the first dog tooth meshes with the first tooth and the second dog tooth meshes with the second tooth. At this step, an axial thrust force is applied to the first ring to separate the first dog tooth and the first tooth. Thereby, while achieving a seamless shift, it is possible to suppress the elastic force required of the spring by the amount of thrust that the thrust generating section applies to the first ring. Furthermore, since there is no need to increase the backlash between the second tooth and the second dog tooth, it is possible to suppress impact noise that occurs when torque is transmitted.

The axial position of the first fork is fixed to the first rod in the neutral region in a state where the elastic force of the spring is not applied to the first fork. Since the first fork can be prevented from vibrating by the elastic force of the spring, the first rod is moved in the axial direction to engage the first dog tooth of the first ring with the first tooth of the first gear. The position of the first ring can be easily controlled when the first ring is moved in the axial direction via the fork. Therefore, the operability of the first fork can be ensured as the first rod moves.

According to the transmission according to the second aspect, the third gear is provided with the third tooth on the end surface in the axial direction of the third gear arranged on the shaft. The first ring is provided with third dog teeth that mesh with the third teeth on an end surface in the axial direction opposite to the end surface on which the first dog teeth are formed. Since the spring is preloaded in the neutral region, the elastic force generated by the initial displacement of the spring can be increased. Therefore, the first fork that has reached the neutral position by separating the first dog teeth from the first tooth can be prevented from approaching the third gear beyond that position. Therefore, double meshing in which the second dog tooth meshes with the second tooth and the third dog tooth meshes with the third tooth can be prevented from occurring.

According to the transmission according to claim 3 , an elongated hole extending in the axial direction is formed in one of the first rod and the first fork, and the elongated hole is arranged inside the elongated hole in the other of the first rod and the first fork. The pin is fixed. The elongated hole has an axial length set such that an axial gap is formed between the inner surface of the elongated hole and the pin in the release region. Therefore, while the relative movement of the first fork in the axial direction is not restricted, the rotation of the first fork can be restricted by the pin hitting the inner surface of the elongated hole.

According to the transmission according to the fourth aspect, an elastic body having a static spring constant smaller than the static spring constant of the spring is interposed between the spring and the first fork. Since changes in the elastic energy of the spring can be absorbed by the elastic body , shocks during gear changes can be suppressed.

According to the transmission according to claim 5 , the shift drum engages with the first tooth in the release region before setting the axial position of the second rod so that the second dog tooth engages with the second tooth. The axial position of the first rod begins to be set so as to disengage the first dog teeth. As a result, the elastic force of the spring can be prevented from canceling out the thrust in the axial direction generated by the thrust generating section. Therefore, the engagement between the first tooth and the first dog tooth can be easily released.

In the release region, the shift drum sets the first rod to a neutral position so as to release the first dog tooth that meshes with the first tooth, and then sets the second rod so that the second dog tooth meshes with the second tooth. Set the axial position of. Therefore, the engagement between the first tooth and the first dog tooth can be more easily released.

It is a skeleton diagram of a transmission in one embodiment. FIG. 3 is a perspective view of a first hub with a first ring arranged thereon. FIG. 2 is a schematic diagram of a transmission in which a first rod and a second rod are in a neutral position. FIG. 3 is a cross-sectional view of the first rod on which the first fork is arranged. FIG. 3 is a schematic diagram of the transmission during drive driving in a low gear. FIG. 3 is a schematic diagram of the transmission when switching from a low gear to a high gear. FIG. 3 is a schematic diagram of the transmission when switching from a low gear to a high gear. FIG. 3 is a schematic diagram of the transmission during drive driving in a high speed gear.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, a schematic configuration of a transmission 1 according to the present invention will be explained with reference to FIG. FIG. 1 is a skeleton diagram of a transmission 1 in one embodiment. The transmission 1 includes a drive shaft 2 to which power is input, and a driven shaft 3 arranged parallel to the drive shaft 2. An output gear 4 is arranged on the driven shaft 3. The drive shaft 2 and the driven shaft 3 support a first gear 10, a second gear 20, a third gear 30, a fourth gear 40, a fifth gear 50, and a sixth gear 60, which constitute a plurality of gear stages. In this embodiment, the transmission 1 is mounted on an automobile (not shown).

The first gear 10 includes a drive gear 11 fixed to the drive shaft 2 so as not to be relatively rotatable, and a driven gear 12 fixed to the driven shaft 3 so as to be relatively rotatable while constantly meshing with the drive gear 11. The second gear 20 includes a drive gear 21 fixed to the drive shaft 2 so as to be relatively rotatable, and a driven gear 22 fixed to the driven shaft 3 so as not to be relatively rotatable while constantly meshing with the drive gear 21. The third speed gear 30 includes a drive gear 31 fixed to the drive shaft 2 so as not to be relatively rotatable, and a driven gear 32 fixed to the driven shaft 3 so as to be relatively rotatable while constantly meshing with the drive gear 31.

The fourth gear 40 includes a drive gear 41 fixed to the drive shaft 2 so as to be relatively rotatable, and a driven gear 42 fixed to the driven shaft 3 so as not to be relatively rotatable while always meshing with the drive gear 41. The fifth gear 50 includes a drive gear 51 fixed to the drive shaft 2 so as to be relatively rotatable, and a driven gear 52 fixed to the driven shaft 3 so as not to be relatively rotatable while constantly meshing with the drive gear 51. The 6th gear 60 includes a drive gear 61 fixed to the drive shaft 2 so as to be relatively rotatable, and a driven gear 62 fixed to the driven shaft 3 so as not to be relatively rotatable while always meshing with the drive gear 61.

The transmission 1 further includes a shift device 70 that selectively couples gears to the drive shaft 2 and the driven shaft 3. The shift device 70 includes a first hub 71, a second hub 72, a third hub 73, a first ring 81, a second ring 82, a third ring 83, a first fork 101, a second fork 102, a third fork 103, It includes a first rod 104, a second rod 106, a third rod 108, and a shift drum 110.

The first hub 71 is an annular member disposed between the drive gear 41 and the drive gear 61 and coupled to the drive shaft 2 . The second hub 72 is an annular member disposed between the drive gear 21 and the drive gear 51 and coupled to the drive shaft 2 . The third hub 73 is an annular member disposed between the driven gear 12 and the driven gear 32 and coupled to the driven shaft 3.

A first tooth 43 that protrudes in the axial direction toward the first hub 71 is provided on the end surface of the drive gear 41 in the axial direction. A third tooth 63 that protrudes in the axial direction toward the first hub 71 is provided on the axial end surface of the drive gear 61 . A second tooth 53 that protrudes in the axial direction toward the second hub 72 is provided on an axial end surface of the drive gear 51 . A fourth tooth 23 that protrudes axially toward the second hub 72 is provided on the axial end surface of the drive gear 21 . A fifth tooth 13 that protrudes axially toward the third hub 73 is provided on an axial end surface of the driven gear 12 . A sixth tooth 33 is provided on an axial end surface of the driven gear 32 and protrudes in the axial direction toward the third hub 73 .

The first ring 81, the second ring 82, and the third ring 83 are rotatably engageable and axially movable with respect to the first hub 71, the second hub 72, and the third hub 73, respectively. They are arranged on the outer peripheries of the hub 71, the second hub 72, and the third hub 73, respectively. On the axial end surface of the first ring 81, first dog teeth 84 and 85 (see FIG. 3) protrude in the axial direction toward the drive gear 41, and first dog teeth 84 and 85 (see FIG. 3) protrude in the axial direction toward the drive gear 61. Three dog teeth 88, 89 (see FIG. 3) are provided.

On the axial end surface of the second ring 82, second dog teeth 93, 94 (see FIG. 3) protrude in the axial direction toward the drive gear 51, and second dog teeth 93, 94 (see FIG. 3) protrude in the axial direction toward the drive gear 21. Four dog teeth 97, 98 (see FIG. 3) are provided. On the axial end surface of the third ring 83, there are fifth dog teeth (not shown) that protrude in the axial direction toward the driven gear 12, and sixth dog teeth that protrude in the axial direction toward the driven gear 32. (not shown) is provided.

The first fork 101, the second fork 102, and the third fork 103 are attached to the first ring 81, the second ring 82, and the third ring 83, respectively. The first fork 101, the second fork 102, and the third fork 103 are fixed to the first rod 104, the second rod 106, and the third rod 108, respectively.

The shift drum 110 is a cylindrical member in which a first cam groove 111, a second cam groove 112, and a third cam groove 113 extending in the circumferential direction are formed on the outer periphery. The shift drum 110 is rotatably fixed to the case C, and rotated around a central axis by a motor (not shown). The first engaging portion 105 disposed on the first rod 104 engages with the first cam groove 111, and the second engaging portion 107 disposed on the second rod 106 engages with the second cam groove 112. A third engaging portion 109 disposed on the third rod 108 engages with the third cam groove 113.

The shift drum 110 rotates based on an operation signal from a shift lever (not shown), or based on an accelerator opening degree and a vehicle speed signal generated by operation of an accelerator pedal (not shown). When the shift drum 110 rotates, the first engaging portion 105, the second engaging portion 107, and the third engaging portion 109 are guided by the first cam groove 111, the second cam groove 112, and the third cam groove 113, respectively. The first fork 101, the second fork 102, and the third fork 103 move in the axial direction via the first rod 104, the second rod 106, and the third rod 108. As the first fork 101, second fork 102, and third fork 103 move in the axial direction, the first ring 81, the second ring 82, and the third ring 83 move in the axial direction.

The first hub 71 and the first ring 81 will be explained with reference to FIG. 2. FIG. 2 is a perspective view of the first hub 71 on which the first ring 81 is arranged. The configurations of the second hub 72 and the third hub 73 are the same as the configuration of the first hub 71, and the configurations of the second ring 82 and the third ring 83 are the same as the configuration of the first ring 81. Therefore, descriptions of the second hub 72, third hub 73, second ring 82, and third ring 83 will be omitted.

As shown in FIG. 2, a spline 74 coupled to the drive shaft 2 (see FIG. 1) is formed on the inner peripheral surface of the first hub 71. A groove 75 parallel to the central axis O of the first hub 71 is formed on the outer peripheral surface of the first hub 71 . The groove 75 is formed over the entire length of the first hub 71 in the axial direction.

The first ring 81 has first dog teeth 84, 85 that protrude from one end surface along the central axis O of the first ring 81, and third dog teeth 88, 89 that protrude in the axial direction from the other end surface. , is equipped with. The central axis O of the first hub 71 and the first ring 81 coincides with the central axis of the drive shaft 2. In this embodiment, the first dog tooth 84 is provided at the same position as the third dog tooth 88, and the first dog tooth 85 is provided at the same position as the third dog tooth 89. The first dog tooth 84 is longer than the first dog tooth 85 in the axial direction, and the third dog tooth 88 is longer than the third dog tooth 89 in the axial direction. The first dog teeth 84 are arranged alternately with the first dog teeth 85 in the circumferential direction, and the third dog teeth 88 are arranged alternately with the third dog teeth 89 in the circumferential direction.

The first dog teeth 84, 85 include a first surface 86 facing one circumferential direction, and a second surface 87 opposite the first surface 86 and facing the other circumferential direction. There is. The third dog teeth 88, 89 include a first surface 90 facing one side in the circumferential direction, and a second surface 91 opposite to the first surface 90 and facing the other side in the circumferential direction. There is. The first surfaces 86 and 90 are inclined surfaces that are inclined with respect to a virtual plane (not shown) parallel to the central axis O. The second surfaces 87 and 91 are surfaces parallel to the central axis O. The first surfaces 86 and 90 are inclined so that as they move away from the first ring 81 in the axial direction, they approach the second surfaces 87 and 91, respectively.

Teeth 92 parallel to the central axis O are provided on the inner surfaces of the first dog teeth 84 and the third dog teeth 88 . The teeth 92 are continuously continuous over the entire length of the first dog teeth 84 and the third dog teeth 88. The teeth 92 of the first ring 81 fit into the grooves 75 of the first hub 71 so that the first ring 81 can move axially relative to the first hub 71; Can't rotate around it.

FIG. 3 is a schematic diagram of the transmission 1 in which the first rod 104 and the second rod 106 are in the neutral position. In FIG. 3, illustration of the third cam groove 113 of the shift drum 110 and the drive gear 21 is omitted. The first engaging portion 105 and the second engaging portion 107 that respectively engage the first cam groove 111 and the second cam groove 112 of the shift drum 110 are located in the neutral region 114 of the shift drum 110, so that the first Rod 104 and second rod 106 are set to neutral positions.

A spring 129 (see FIG. 4) is disposed between the first rod 104 and the first fork 101, which biases the first fork 101 in the axial direction by elastic force. Similarly, a spring (not shown) is disposed between the second rod 106 and the second fork 102 as well, which biases the second fork 102 in the axial direction with elastic force. The structure of arranging the spring between the second rod 106 and the second fork 102 is the same as the structure of arranging the spring 129 between the first rod 104 and the first fork 101, so the explanation will be omitted.

FIG. 4 is a cross-sectional view of the first rod 104 on which the first fork 101 is disposed, when the first rod 104 is in the neutral position. In FIG. 4, illustration of a portion of the first rod 104 in the axial direction and a portion of the first fork 101 is omitted.

The attachment part 120 of the first fork 101 is formed in a cylindrical shape and is attached to the outer periphery of the first rod 104. The mounting portion 120 is formed with a hole 121 that penetrates in the radial direction. The cylindrical portion 122 surrounds the outer periphery of the first rod 104 with a space therebetween. One end of the cylindrical portion 122 is coupled to the attachment portion 120. A convex portion 123 (stopper) that protrudes radially inward is provided at the other end of the cylindrical portion 122.

Grooves are formed in the first rod 104 at intervals in the axial direction, and retaining rings 124 and 125 are respectively fixed to the grooves. The retaining ring 124 is located inside the cylindrical portion 122. Washers 126 and 127 each having an outer diameter larger than the outer diameter of the retaining rings 124 and 125 are arranged on the first rod 104 inside the retaining rings 124 and 125 in the axial direction. The washers 126 and 127 are arranged inside the cylindrical portion 122 with a space between them in the axial direction.

An annular elastic body 128 made of rubber, synthetic resin, or the like is interposed between the washer 127 and the convex portion 123 of the cylindrical portion 122 . A spring 129 is arranged between washer 126 and washer 127. In this embodiment, spring 129 is a compression coil spring. Since the distance between washer 126 and washer 127 is less than the free length of spring 129, spring 129 is preloaded. Due to the elastic force of the preloaded spring 129, the washer 126 is pressed against the retaining ring 124, and the washer 127 is pressed against the retaining ring 125.

A cylindrical spacer 130 (stopper) is arranged between the washer 126 and the mounting portion 120. An annular elastic body 131 made of rubber or synthetic resin is interposed between the spacer 130 and the attachment portion 120. The static spring constants of the elastic bodies 128 and 131 are smaller than the static spring constant of the spring 129.

The attachment portion 120, the elastic body 131, the spacer 130, and the washer 126 are lined up with no gaps between each other, and the washer 127, the elastic body 128, and the convex portion 123 are lined up with each other without any gaps. Due to the elastic force of the preloaded spring 129, it is difficult to form a gap between the spacer 130 and the washer 126, and it is difficult to form a gap between the elastic body 128 and the convex portion 123, so that the first rod 104 is in the neutral position. , the axial position of the first fork 101 on the first rod 104 is fixed without wobbling. Since the restoring of the spring 129 is restricted by the retaining rings 124 and 125, the elastic force of the spring 129 is not applied to the first fork 101 (attachment portion 120) when the first rod 104 is in the neutral position.

An elongated hole 132 extending in the axial direction is formed in a portion of the first rod 104 where the attachment portion 120 is arranged. The elongated hole 132 passes through the first rod 104. The elongated hole 132 forms a first wall 133 and a second wall 134 in the first rod 104 that face each other in the axial direction. The pin 135 is fixed to the hole 121 formed in the attachment part 120 and is disposed between the first wall 133 and the second wall 134. As a result, rotation of the first fork 101 with respect to the first rod 104 is restricted.

Since the distance between the first wall 133 and the second wall 134 is larger than the thickness of the pin 135, there is an axial distance between the pin 135 and the first wall 133 and between the pin 135 and the second wall 134. A gap is provided for each. This allows the first rod 104 to move relative to the first fork 101 until the first wall 133 hits the pin 135. Furthermore, the first rod 104 can move relative to the first fork 101 until the second wall 134 hits the pin 135.

The explanation will be given by returning to FIG. 3. The first teeth 43 of the drive gear 41 (first gear) include high teeth 43a and regular teeth 43b having a shorter tooth length than the high teeth 43a. The high teeth 43a and the regular teeth 43b are arranged alternately in the circumferential direction. The first tooth 43 includes a third surface 44 facing one circumferential direction, and a fourth surface 45 opposite the third surface 44 and facing the other circumferential direction. The third surface 44 faces the first surface 86 of the first ring 81 , and the fourth surface 45 faces the second surface 87 of the first ring 81 .

The first surface 86 and the third surface 44 are inclined to generate a thrust that causes the drive gear 41 and the first ring 81 to separate in the axial direction in accordance with the torque in the direction that brings the first surface 86 and the third surface 44 into contact. It is a surface. The third surface 44 is inclined toward the fourth surface 45 as it goes away from the drive gear 41 . The angle of inclination of the third surface 44 with respect to a virtual plane (not shown) parallel to the central axis O is the same as the angle of inclination θ of the first surface 86.

The second surface 87 and the fourth surface 45 are surfaces where the drive gear 41 and the first ring 81 are not separated from each other in the axial direction when the second surface 87 and the fourth surface 45 are brought into contact with each other to transmit torque. . In this embodiment, the fourth surface 45 is a surface parallel to the central axis O.

The second teeth 53 of the drive gear 51 (second gear) include high teeth 53a and regular teeth 53b having a shorter tooth length than the high teeth 53a. The high teeth 53a and the regular teeth 53b are arranged alternately in the circumferential direction. The second tooth 53 includes a third surface 54 facing one circumferential direction, and a fourth surface 55 opposite the third surface 54 and facing the other circumferential direction.

The second ring 82 includes second dog teeth 93 and 94 protruding from one end surface of the second ring 82 . The second dog tooth 93 is longer than the second dog tooth 94 in the axial direction. The second dog teeth 93 and the second dog teeth 94 are arranged alternately in the circumferential direction. The second dog teeth 93, 94 include a first surface 95 facing one side in the circumferential direction, and a second surface 96 opposite to the first surface 95 and facing the other side in the circumferential direction. There is. The first surface 95 is an inclined surface that is inclined with respect to a virtual plane (not shown) parallel to the central axis O. The second surface 96 is a surface parallel to the central axis O. The first surface 95 is inclined so that it approaches a second surface 96 as it moves away from the second ring 82 in the axial direction. The first surface 95 faces the third surface 54 of the drive gear 51, and the second surface 96 faces the fourth surface 55 of the drive gear 51.

The first surface 95 and the third surface 54 are inclined to generate a thrust that causes the drive gear 51 and the second ring 82 to separate in the axial direction in response to a torque in a direction that brings the first surface 95 and the third surface 54 into contact. It is a surface. The third surface 54 is inclined toward the fourth surface 55 as it goes away from the drive gear 51. The angle of inclination of the third surface 54 with respect to a virtual plane (not shown) parallel to the central axis O is the same as the angle of inclination θ of the first surface 95.

The second surface 96 and the fourth surface 55 are surfaces where the drive gear 51 and the second ring 82 are not separated from each other in the axial direction when the second surface 96 and the fourth surface 55 are brought into contact to transmit torque. . In this embodiment, the fourth surface 55 is a surface parallel to the central axis O.

The third tooth 63 of the drive gear 61 (third gear) includes high teeth 63a and regular teeth 63b having a shorter tooth length than the high teeth 63a. The high teeth 63a and the regular teeth 63b are arranged alternately in the circumferential direction. The third tooth 63 includes a third surface 64 facing one circumferential direction, and a fourth surface 65 opposite the third surface 64 and facing the other circumferential direction. The third surface 64 faces the first surface 90 of the first ring 81 , and the fourth surface 65 faces the second surface 91 of the first ring 81 .

The first surface 90 and the third surface 64 are inclined to generate a thrust that causes the drive gear 61 and the first ring 81 to be separated in the axial direction according to the torque in the direction that brings the first surface 90 and the third surface 64 into contact. It is a surface. The third surface 64 is inclined toward the fourth surface 65 as it goes away from the drive gear 61 . The angle of inclination of the third surface 64 with respect to a virtual plane (not shown) parallel to the central axis O is the same as the angle of inclination θ of the first surface 90.

The second surface 91 and the fourth surface 65 are surfaces where the drive gear 61 and the first ring 81 are not separated from each other in the axial direction when the second surface 91 and the fourth surface 65 are brought into contact to transmit torque. . In this embodiment, the fourth surface 65 is a surface parallel to the central axis O.

With reference to FIGS. 5 to 8, the operation of the transmission 1 when changing gears (upshifting) to a high speed gear will be described. In this embodiment, a shift from the 4th gear 40 to the 5th gear 50 will be explained as an example, but since the operation of shifting to other gears is the same, the operation of upshifting and downshifting of other gears will be explained below. The explanation will be omitted.

FIG. 5 is a schematic diagram of the transmission 1 during drive driving in a low gear (4th gear 40). In FIGS. 5 to 8, the rotation direction of the drive gears 41, 51, 61, the first ring 81, and the second ring 82 is downward (in the direction of arrow R) along the plane of the paper. The rotation direction of the shift drum 110 is upward (direction of arrow S) along the plane of the paper. The second surfaces 87 and 96 of the first ring 81 and the second ring 82 face each other in the rotation direction of the first ring 81 and the second ring 82 .

When the shift drum 110 is rotated and the first engagement portion 105 moves from the neutral area 114 of the shift drum 110 to the first engagement area 115, the first rod 104 and the first fork 101 are connected to the drive gear 41 (first gear). The first dog teeth 84 and 85 of the first ring 81 mesh with the first teeth 43 of the drive gear 41. In the neutral region 114, the elastic force of the spring 129 (see FIG. 4) is not applied to the first fork 101, so vibrations of the spring 129 and the like are not transmitted to the first fork 101. In this state, the first fork 101 is fixed to the first rod 104 without wobbling, so that the positional accuracy of the first fork 101 as the first rod 104 moves can be ensured.

During drive driving in which power is transmitted from the drive gear 41 to the driven gear 42 (see FIG. 1), the second surface 87 of the first ring 81 is in contact with the fourth surface 45 of the drive gear 41. At this time, a circumferential gap is created between the first surface 86 and the third surface 44. When the second surface 87 and the fourth surface 45 are brought into contact to transmit torque, no thrust force is applied to separate the drive gear 41 and the first ring 81 in the axial direction. The gear is prevented from coming off by limiting the axial movement of the engaging portion 105, the friction between the second surface 87 and the fourth surface 45, and the elastic force due to the preload of the spring 129 (see FIG. 4), thereby reducing the drive torque. introduce.

6 and 7 are schematic diagrams of the transmission 1 in the middle of shifting from a low gear (4th gear 40) to a high gear (5th gear 50), and FIG. 8 is a drive running in the high gear (5th gear 50). FIG. 2 is a schematic diagram of the transmission 1 at the time.

As shown in FIG. 6, when the shift drum 110 is rotated and the first engagement portion 105 moves from the first engagement area 115 of the shift drum 110 to the release area 116 during driving in a low gear (4th gear 40), Since the first ring 81, which presses the second surface 87 against the fourth surface 45 and transmits the driving torque, cannot move in the axial direction, the retaining ring 125 (see FIG. 4) of the first rod 104 compresses the spring 129. Then, the first rod 104 moves to the neutral position. This creates a gap between the convex portion 123 of the cylindrical portion 122 and the elastic body 128.

At this time, the first wall 133 (see FIG. 4) approaches the pin 135, but there is an axial gap between the pin 135 and the first wall 133. Thereby, the relative movement of the first fork 101 in the axial direction can be prevented from being restricted. On the other hand, the second rod 106 does not move in the axial direction while the second engaging part 107 is located in the holding part 112a that keeps the second rod 106 in the neutral position in the release area 116 of the second cam groove 112.

As shown in FIG. 7, when the shift drum 110 is further rotated, the second engaging portion 107 moves to the inclined portion 112b of the release area 116 of the second cam groove 112, and the second rod 106 moves in the axial direction. do. As a result, the second fork 102 moves to the drive gear 51 (second gear), the second dog teeth 93 and 94 of the second ring 82 approach the drive gear 51, and the second dog teeth 93 of the second ring 82 move toward the second dog tooth 93 of the second ring 82. The tip of the tooth contacts the tip of the second tooth 53 of the drive gear 51 . Since the second dog teeth 93 of the second ring 82 have a longer tooth length than the second dog teeth 94, the second dog teeth 93 can easily mesh with the high teeth 53a of the drive gear 51.

In a state where the first tooth 43 of the drive gear 41 (first gear) and the first dog teeth 84, 85 of the first ring 81 are engaged, the second tooth 53 of the drive gear 51 (second gear) and the second ring When the second dog teeth 93 of 82 are engaged, the drive gear 51 rotates faster than the drive gear 41, so the fourth speed side is in a coasting state and the fifth speed side is in a drive state.

In the fourth gear 40, the first surface 86 of the first ring 81 and the third surface 44 of the drive gear 41 are in a coasting state, and due to the inclination angle θ of the first surface 86 and the third surface 44, the torque is In response, a thrust force is generated that causes the drive gear 41 and the first ring 81 to move away from each other in the axial direction. Due to the thrust, the first ring 81 is rotated so that the teeth 92 formed on the inner circumferential surface of the first ring 81 are fitted into the grooves 75 formed on the outer circumferential surface of the first hub 71 (see FIG. 2). The first fork 101 moves in the axial direction while transmitting torque. At this time, the spring 129 (see FIG. 4) is restored and the convex portion 123 approaches the elastic body 128.

When the first ring 81 is separated from the drive gear 41, even if there is a radial gap between the teeth 92 and the groove 75, the axially extending portion of the groove 75 is in the axially extending portion of the tooth 92. Since the first ring 81 is in contact with the first hub 71, the first ring 81 becomes difficult to tilt with respect to the first hub 71, and the moment of force of the first ring 81 can be suppressed. This can suppress the friction of the teeth 92 that rub against the grooves 75 and move in the axial direction. As a result, it is possible to suppress noise and vibration caused by the internal circulation torque being released when the first ring 81 separates from the drive gear 41.

When the spring 129 (see FIG. 4) is restored and the convex portion 123 collides with the elastic body 128, the first fork 101 stops moving in the axial direction, and the first ring 81 is set at the neutral position. An impact is generated by changes in kinetic energy and elastic energy of the spring 129 when the convex portion 123 hits the elastic body 128 . However, since it is the first fork 101 and the first ring 81 that have moved in the axial direction, the mass of the first rod 104 is greater than when the entire movement of the first rod 104, first fork 101, and first ring 81 is stopped. The change in kinetic energy can be reduced by the amount that is not included. Furthermore, since the spring 129 buffers the impact, it is possible to suppress the noise and vibrations that occur due to the impact. Furthermore, since the elastic body 128 absorbs changes in the elastic energy of the spring 129, it is possible to further suppress noise and vibration caused by impact.

Since the spring 129 is preloaded, the elastic force created by the initial displacement of the spring 129 can be increased. Therefore, the first fork 101 that has reached the neutral position due to the separation of the first ring 81 from the drive gear 41 can be prevented from approaching the drive gear 61 (third gear) beyond that position. Therefore, it is possible to prevent double meshing in which the second dog teeth 93 and 94 mesh with the second tooth 53 of the drive gear 51 and the third dog teeth 88 and 89 mesh with the third tooth 63 of the drive gear 61. .

On the other hand, the fifth speed gear 50 is in a drive state in which the second surface 96 of the second ring 82 and the fourth surface 55 of the drive gear 51 are in contact, and the drive gear 51 and the second ring 82 are separated in the axial direction. No thrust is generated. Therefore, the second rod 106 moves in the axial direction as the second engaging portion 107 is guided by the inclined portion 112b of the second cam groove 112, and the second fork 102 and the second ring 82 are moved closer to the drive gear 51. As they approach, the second dog teeth 93, 94 of the second ring 82 and the second teeth 53 of the drive gear 51 become more deeply engaged.

When the meshing becomes deeper, friction occurs between the second surface 96 of the second ring 82 and the fourth surface 55 of the drive gear 51. However, since a preload is applied to the spring 129 (see FIG. 4) disposed on the second rod 106, as the second rod 106 moves, it resists the friction between the second surface 96 and the fourth surface 55. The second fork 102 can be moved to deepen the engagement.

In the release area 116 of the shift drum 110, before setting the axial position of the second rod 106 so that the second dog teeth 93, 94 mesh with the second teeth 53 by the inclined portion 112b of the second cam groove 112. , the axial position of the first rod 104 begins to be set so that the first dog teeth 84 and 85 meshing with the first tooth 43 are disengaged. As a result, the elastic force of the spring 129 can be prevented from canceling out the axial thrust generated between the first surface 86 and the third surface 44. Therefore, the engagement between the first tooth 43 and the first dog teeth 84, 85 can be easily released. In particular, in the release area 116 of the shift drum 110, after the first rod 104 is set to the neutral position so as to release the engagement of the first dog teeth 84, 85 that engage the first teeth 43, the second dog teeth 93, 94 are set to the neutral position. Since the axial position of the second rod 106 is set so as to mesh with the second tooth 53, the meshing between the first tooth 43 and the first dog teeth 84, 85 can be more easily released.

As shown in FIG. 8, when the shift drum 110 is further rotated and the first engaging part 105 and the second engaging part 107 move to the second engagement area 117 of the shift drum 110, the first rod 104 is brought to the neutral position. The second rod 106 is maintained in a position where the second ring 82 and the drive gear 51 mesh with each other.

As described above, in the transmission 1, when shifting from a low gear to a high gear, the first dog teeth 84 and 85 of the first ring 81 mesh with the first teeth 43 of the first gear constituting the lower gear, and When the second dog teeth 93 and 94 of the second ring 82 mesh with the second tooth 53 of the second gear constituting the gear stage, due to internal circulation torque, the force of The first ring 81 coupled to the first gear, which rotates slowly, is pushed out in the axial direction by the thrust generated between the first surface 86 and the third surface 44.

As a result, the elastic force required of the spring 129 can be suppressed by the amount of the thrust generated between the first surface 86 and the third surface 44 while achieving a so-called seamless shift, which is a shift that suppresses interruptions in the driving torque. The spring 129 only needs to have an elastic force capable of absorbing the impact when the first ring 81 and the first fork 101 move and stop in the axial direction due to the thrust generated between the first surface 86 and the third surface 44. Therefore, the space required for the spring 129 to be displaced can be reduced. Further, since the force applied to the spring 129 to obtain the elastic force of the spring 129 can be reduced, the motor (not shown) for rotating the shift drum 110 can be made smaller. Therefore, the ease of assembling the spring 129 can be improved, and furthermore, the increase in size of the transmission 1 can be suppressed.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments in any way, and it is easily understood that various improvements and modifications can be made without departing from the spirit of the present invention. This can be inferred. For example, the number and arrangement of gear stages of the transmission 1, the shape of the cam grooves 111 and 112 formed in the shift drum 110, the number and shape of the grooves 75 formed in the first hub 71, the number and shape of the grooves 75 formed in the first ring 81, etc. The number and shape of the teeth 92 can be set as appropriate.

In the embodiment, the fourth surface 45 of the first tooth 43 provided on the drive gear 41, the fourth surface 55 of the second tooth 53 provided on the drive gear 51, and the first dog tooth provided on the first ring 81. Although the case has been described in which the second surfaces 87 of the teeth 84 and 85 and the second surfaces 96 of the second dog teeth 93 and 94 provided on the second ring 82 are surfaces parallel to the central axis O, this is not necessarily the case. It is not limited to. When the second surfaces 87, 96 and the fourth surfaces 45, 55 are in contact and transmitting torque, the axial component of the force due to the torque and the second surfaces 87, 96, the fourth surfaces 45, 55, It is sufficient that the resultant force of the axial component of the frictional force with 55 does not act in a direction that separates the first ring 81 and the second ring 82 from the drive gears 41 and 51. As long as this relationship is satisfied, the second surfaces 87, 96 and the fourth surfaces 45, 55 may be inclined with respect to a virtual plane (not shown) parallel to the central axis O.

In the embodiment, the third surface 44 of the first tooth 43 provided on the drive gear 41 and the first surface 86 of the first dog teeth 84 and 85 provided on the first ring 81 are driven according to the torque. Although a case has been described in which the thrust generating section generates a thrust force that separates the gear 41 and the first ring 81 in the axial direction, the present invention is not necessarily limited to this. For example, as in the transmission described in Japanese Unexamined Patent Application Publication No. 2012-127471, the inclination angle of the first surface 86 and the third surface 44 is made almost zero, and instead of the teeth 92 provided on the first ring 81, the first A cylindrical projection is provided on the ring 81, and instead of the parallel groove 75 provided on the first hub 71, a V-shaped cam groove that is inclined with respect to the plane containing the central axis O is provided on the outer peripheral surface of the first hub 71. Of course, it is possible to form the first ring 81 into a cam groove and arrange the protrusion of the first ring 81 in the cam groove. Even when the cam groove of the first hub 71 and the protrusion of the first ring 81 are used as thrust generating parts, the same effects as in this embodiment can be achieved.

In the embodiment, a case has been described in which the spring 129 is a compression coil spring, but the spring 129 is not necessarily limited to this. It is of course possible to use a spring other than a coil spring for the spring 129.

In the embodiment, a case has been described in which the elastic body 128 is interposed between the washer 127 and the convex portion 123, and the elastic body 131 is interposed between the spacer 130 and the attachment portion 120. Of course, one can be omitted. Even without the elastic bodies 128 and 131, the spring 129 can buffer the impact. Furthermore, it is naturally possible to arrange the elastic body 131 between the spacer 130 and the washer 126.

In the embodiment, a case has been described in which the elongated hole 132 is provided in the first rod 104 and the pin 135 is provided in the attachment portion 120, but the present invention is not necessarily limited to this. On the contrary, it is of course possible to provide an elongated hole in the attachment portion 120 and provide a pin in the first rod 104.

In the embodiment, a case has been described in which the transmission of drive torque is switched between the drive gears 41 and 51 disposed on the drive shaft 2, but the present invention is not necessarily limited to this. Switching the transmission of driving torque between the driven gear 12 arranged on the driven shaft 3 and the driving gear 21, or switching the transmission of the driving torque between the driven gear 32 arranged on the driven shaft 3 and the driving gear 41. In this case, the same effects as in this embodiment can be achieved. In these cases, similarly to the embodiment, the gear that constitutes the low speed gear is the first gear, and the gear that constitutes the high speed gear is the second gear.

In the embodiment, a case has been described in which the transmission 1 is installed in a car, but the invention is not limited to this, and it is of course possible to install the transmission 1 in a construction machine, an industrial vehicle, an agricultural machine, or the like. In this case as well, the transmission 1 can eliminate interruptions in the drive torque during gear changes. As a result, idle rotation of the drive shaft 2 can be eliminated and fuel efficiency can be improved.

1 Transmission 2 Drive shaft (shaft)
3 Driven shaft (shaft)
41 Drive gear (1st gear)
43 First tooth 44 Third surface (part of thrust generation part)
45 Fourth surface 51 Drive gear (second gear)
53 2nd tooth 61 Drive gear (3rd gear)
63 Third tooth 70 Shift device 71 First hub 72 Second hub 81 First ring 82 Second ring 84, 85 First dog tooth 86 First surface (part of thrust generating section)
88, 89 Third dog tooth 93, 94 Second dog tooth 101 First fork 102 Second fork 104 First rod 105 First engaging portion 106 Second rod 107 Second engaging portion 110 Shift drum 111 First cam groove 112 Second cam groove 114 Neutral region 116 Release region 128, 131 Elastic body 129 Spring 132 Elongated hole 133 First wall (inner surface of elongated hole)
134 2nd wall (inner surface of long hole)
135 pin

Claims (5)

a first gear disposed on the shaft, forming a predetermined gear stage, and having first teeth on an end surface in the axial direction;
a second gear, which constitutes a higher gear stage than the gear stage constituted by the first gear, is disposed on the shaft, and has second teeth provided on an end surface in the axial direction;
a shift device that selectively couples the first gear and the second gear to the shaft,
The shift device includes an annular first hub and a second hub coupled to the shaft;
First dog teeth disposed on the outer periphery of the first hub, capable of rotationally engaging with the first hub and movable in the axial direction, and meshing with the first teeth are provided on an axial end surface. the first ring;
Second dog teeth disposed on the outer periphery of the second hub, rotatably engaging with the second hub and movable in the axial direction, and meshing with the second teeth are provided on an axial end surface. a second ring;
a first fork attached to the first ring;
a second fork attached to the second ring;
a shift drum in which a first cam groove and a second cam groove are formed;
a first rod in which a first engaging portion that engages with the first cam groove is disposed, and that moves the first fork in the axial direction along the first cam groove;
A transmission comprising: a second rod in which a second engaging portion that engages with the second cam groove is disposed, and that moves the second fork in the axial direction along the second cam groove;
The shift drum has a neutral region in which the first rod and the second rod are set at neutral positions;
The axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the first rod is set such that the first dog tooth meshes with the first tooth. a release area for setting the axial position;
The shift device includes a spring that is interposed between the first rod and the first fork and biases the first fork in the axial direction by an elastic force in the release region;
a thrust generating section that applies an axial thrust to the first ring to separate the first dog tooth and the first tooth in the release region, in addition to the elastic force of the spring ;
In the transmission, the first fork has an axial position fixed to the first rod in a state where the elastic force of the spring is not applied to the first fork in the neutral region . a first gear disposed on the shaft, forming a predetermined gear stage, and having first teeth on an end surface in the axial direction;
a second gear, which constitutes a higher gear stage than the gear stage constituted by the first gear, is disposed on the shaft, and has second teeth provided on an end surface in the axial direction;
a third gear disposed on the shaft and having third teeth on an end surface in the axial direction;
a shift device that selectively couples the first gear and the second gear to the shaft,
The shift device includes an annular first hub and a second hub coupled to the shaft;
First dog teeth disposed on the outer periphery of the first hub, capable of rotationally engaging with the first hub and movable in the axial direction, and meshing with the first teeth are provided on an axial end surface. the first ring;
Second dog teeth disposed on the outer periphery of the second hub, rotatably engaging with the second hub and movable in the axial direction, and meshing with the second teeth are provided on an axial end surface. a second ring;
a first fork attached to the first ring;
a second fork attached to the second ring;
a shift drum in which a first cam groove and a second cam groove are formed;
a first rod in which a first engaging portion that engages with the first cam groove is disposed, and that moves the first fork in the axial direction along the first cam groove;
A transmission comprising: a second rod in which a second engaging portion that engages with the second cam groove is disposed, and that moves the second fork in the axial direction along the second cam groove;
The shift drum has a neutral region in which the first rod and the second rod are set at neutral positions;
The axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the first rod is set such that the first dog tooth meshes with the first tooth. a release area for setting the axial position;
The shift device includes a spring that is interposed between the first rod and the first fork and biases the first fork in the axial direction by an elastic force in the release region;
a thrust generating section that applies an axial thrust to the first ring to separate the first dog tooth and the first tooth in the release region, in addition to the elastic force of the spring ;
The first ring is provided with third dog teeth that mesh with the third teeth on an end surface in the axial direction opposite to the end surface where the first dog teeth are provided,
The transmission wherein the spring is preloaded in the neutral region . a first gear disposed on the shaft, forming a predetermined gear stage, and having first teeth on an end surface in the axial direction;
a second gear, which constitutes a higher gear stage than the gear stage constituted by the first gear, is disposed on the shaft, and has second teeth provided on an end surface in the axial direction;
a shift device that selectively couples the first gear and the second gear to the shaft,
The shift device includes an annular first hub and a second hub coupled to the shaft;
First dog teeth disposed on the outer periphery of the first hub, capable of rotationally engaging with the first hub and movable in the axial direction, and meshing with the first teeth are provided on an axial end surface. the first ring;
Second dog teeth disposed on the outer periphery of the second hub, rotatably engaging with the second hub and movable in the axial direction, and meshing with the second teeth are provided on an axial end surface. a second ring;
a first fork attached to the first ring;
a second fork attached to the second ring;
a shift drum in which a first cam groove and a second cam groove are formed;
a first rod in which a first engaging portion that engages with the first cam groove is disposed, and that moves the first fork in the axial direction along the first cam groove;
A transmission comprising: a second rod in which a second engaging portion that engages with the second cam groove is disposed, and that moves the second fork in the axial direction along the second cam groove;
The shift drum has a neutral region in which the first rod and the second rod are set at neutral positions;
The axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the first rod is set such that the first dog tooth meshes with the first tooth. a release area for setting the axial position;
The shift device includes a spring that is interposed between the first rod and the first fork and biases the first fork in the axial direction by an elastic force in the release region;
a thrust generating section that applies an axial thrust to the first ring to separate the first dog tooth and the first tooth in the release region, in addition to the elastic force of the spring ;
An elongated hole extending in the axial direction is formed in one of the first rod and the first fork,
A pin disposed inside the elongated hole is fixed to the other of the first rod and the first fork,
The elongated hole has an axial length set such that an axial gap is formed between the inner surface of the elongated hole and the pin in the release region. a first gear disposed on the shaft, forming a predetermined gear stage, and having first teeth on an end surface in the axial direction;
a second gear, which constitutes a higher gear stage than the gear stage constituted by the first gear, is disposed on the shaft, and has second teeth provided on an end surface in the axial direction;
a shift device that selectively couples the first gear and the second gear to the shaft,
The shift device includes an annular first hub and a second hub coupled to the shaft;
First dog teeth disposed on the outer periphery of the first hub, capable of rotationally engaging with the first hub and movable in the axial direction, and meshing with the first teeth are provided on an axial end surface. the first ring;
Second dog teeth disposed on the outer periphery of the second hub, rotatably engaging with the second hub and movable in the axial direction, and meshing with the second teeth are provided on an axial end surface. a second ring;
a first fork attached to the first ring;
a second fork attached to the second ring;
a shift drum in which a first cam groove and a second cam groove are formed;
a first rod in which a first engaging portion that engages with the first cam groove is disposed, and that moves the first fork in the axial direction along the first cam groove;
A transmission comprising: a second rod in which a second engaging portion that engages with the second cam groove is disposed, and that moves the second fork in the axial direction along the second cam groove;
The shift drum has a neutral region in which the first rod and the second rod are set at neutral positions;
The axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the first rod is set such that the first dog tooth meshes with the first tooth. a release area for setting the axial position;
The shift device includes a spring that is interposed between the first rod and the first fork and biases the first fork in the axial direction by an elastic force in the release region;
a thrust generating section that applies an axial thrust force to the first ring that separates the first dog tooth and the first tooth in the release region, apart from the elastic force of the spring;
an elastic body interposed between the spring and the first fork;
A static spring constant of the elastic body is smaller than a static spring constant of the spring . a first gear disposed on the shaft, forming a predetermined gear stage, and having first teeth on an end surface in the axial direction;
a second gear, which constitutes a higher gear stage than the gear stage constituted by the first gear, is disposed on the shaft, and has second teeth provided on an end surface in the axial direction;
a shift device that selectively couples the first gear and the second gear to the shaft,
The shift device includes an annular first hub and a second hub coupled to the shaft;
First dog teeth disposed on the outer periphery of the first hub, capable of rotationally engaging with the first hub and movable in the axial direction, and meshing with the first teeth are provided on an axial end surface. the first ring;
Second dog teeth disposed on the outer periphery of the second hub, rotatably engaging with the second hub and movable in the axial direction, and meshing with the second teeth are provided on an axial end surface. a second ring;
a first fork attached to the first ring;
a second fork attached to the second ring;
a shift drum in which a first cam groove and a second cam groove are formed;
a first rod in which a first engaging portion that engages with the first cam groove is disposed, and that moves the first fork in the axial direction along the first cam groove;
A transmission comprising: a second rod in which a second engaging portion that engages with the second cam groove is disposed, and that moves the second fork in the axial direction along the second cam groove;
The shift drum has a neutral region in which the first rod and the second rod are set at neutral positions;
The axial position of the second rod is set so that the second dog tooth meshes with the second tooth, and the first rod is set such that the first dog tooth meshes with the first tooth. a release area for setting the axial position;
The shift device includes a spring that is interposed between the first rod and the first fork and biases the first fork in the axial direction by an elastic force in the release region;
a thrust generating section that applies an axial thrust to the first ring to separate the first dog tooth and the first tooth in the release region, in addition to the elastic force of the spring ;
In the release area, the shift drum sets the first dog tooth that engages with the first tooth before setting the axial position of the second rod such that the second dog tooth engages with the second tooth. beginning to set the axial position of the first rod to release the engagement;
In the release region, after the first rod is set to the neutral position so as to release the first dog tooth that meshes with the first tooth, the second dog tooth meshes with the second tooth. A transmission that sets the axial position of the second rod .

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