JP7470861B2 - Parking Mechanism - Google Patents

Description

The present invention relates to a parking mechanism for a vehicle.

In a parking mechanism for a vehicle equipped with a transmission having a gear train with multiple speeds provided between an input shaft and an output shaft, and a shift fork that switches the selective engagement of the gear train in accordance with the displacement of a shift cam, Patent Document 1 discloses prior art in which a parking position that simultaneously establishes multiple gear trains is provided on the shift cam.

JP 2011-196521 A

In the prior art, when the parking mechanism is activated while parked on an uphill or downhill slope, gravity acting on the vehicle causes the wheels to rotate and this force is applied to the gear train, resulting in a problem that the circulating torque between the gear trains becomes large and the parking mechanism cannot be released unless the shift cam applies excessive force to the shift fork.

The present invention has been made to solve this problem and aims to provide a parking mechanism that can be released with little force.

In order to achieve this object, the present invention provides a gear train including: shafts arranged parallel to each other; first and second idling gears arranged rotatable relative to the shaft but immovable in the axial direction, each having a first tooth; first and second fixed gears arranged immovable relative to the shaft and meshing with the first and second idling gears, respectively; first and second sleeves arranged immovable relative to the shaft but immovable in the axial direction, each having a second tooth meshing with the first tooth; first and second forks arranged on the first and second sleeves, respectively; and a gear train including a gear train on which the first and second forks are arranged, respectively. A parking mechanism for a vehicle including a transmission having a first and second rods and first and second cams moving the first and second rods in an axial direction, wherein the first and second cams have a locked position in which the second teeth of the first sleeve mesh with the first teeth of the first idling gear and the second teeth of the second sleeve mesh with the first teeth of the second idling gear, and an unlocked position in which at least one of the meshing between the second teeth of the first sleeve and the first teeth of the first idling gear and the meshing between the second teeth of the second sleeve and the first teeth of the second idling gear is released. The first teeth have a first surface facing one side in the circumferential direction and a second surface facing the other side in the circumferential direction, and the second teeth have a third surface facing the first surface and a fourth surface facing the second surface in the locked position. The first surface and the third surface transmit torque in a direction pressing the first surface against the third surface, and the second surface and the fourth surface generate thrust that moves the first tooth and the second tooth axially apart in response to the torque in a direction pressing the second surface against the fourth surface.

According to the first aspect, in the locked position, the second tooth of the first sleeve meshes with the first tooth of the first idling gear, and the second tooth of the second sleeve meshes with the first tooth of the second idling gear. The second tooth has a third surface facing the first surface of the first tooth and a fourth surface facing the second surface of the first tooth in the locked position. The first and third surfaces transmit torque in a direction pressing the first and third surfaces together. When the second and fourth surfaces are pressed together in the unlocked position, a thrust force is generated that separates the first and second teeth in the axial direction in response to the torque in the direction pressing the second and fourth surfaces together, so that the meshing between the second and first teeth is released with a small force. Therefore, the operation of the parking mechanism can be released with a small force.

According to the second aspect, in addition to the first aspect, the angle θ2 between the plane including the axis and the second and fourth surfaces is larger than the angle θ1 between the plane including the axis and the first and third surfaces. This allows the teeth pressed against the second and fourth surfaces to be disengaged before the teeth pressed against the first and third surfaces. Therefore, the parking mechanism can be released smoothly regardless of the state of the vehicle (uphill or downhill).

According to the third aspect, in the first or second aspect, the unlocked position includes a first position where the second tooth of the first sleeve disengages from the first tooth of the first idling gear, and a second position where the second tooth of the second sleeve disengages from the first tooth of the second idling gear. Since the first and second positions are located on both sides of the locking position in the displacement direction of the first and second cams, when the first and second cams cannot be displaced from the unlocking position to the first position to be released, the first and second cams can be displaced to the second position to be released. Similarly, when the second position cannot be released, the first position can be released. This simplifies the mechanism.

According to the fourth aspect, in the first or second aspect, a first spring is interposed between the first rod and the first fork, and a second spring is interposed between the second rod and the second fork. When the first or second spring is displaced from the locked position to the unlocked position, it releases the elastic energy stored in the locked position, and disengages the second tooth of the first sleeve from the first tooth of the first idling gear, or disengages the second tooth of the second sleeve from the first tooth of the second idling gear, so that the mechanism can be released by the restoring force of the spring.

FIG. 2 is a skeleton diagram of a transmission according to one embodiment. FIG. 4 is a schematic diagram of a cam according to the first embodiment. FIG. 1A is a schematic diagram of the parking mechanism during actuation, FIG. 1B is a schematic diagram of the parking mechanism during deactivation, and FIG. 1C is a schematic diagram of the released parking mechanism. 1A is a schematic diagram of the parking mechanism during actuation, FIG. 1B is a schematic diagram of the parking mechanism during deactivation, and FIG. 1C is a schematic diagram of the released parking mechanism. 1A is a schematic diagram of the parking mechanism during actuation, FIG. 1B is a schematic diagram of the parking mechanism during deactivation, and FIG. 1C is a schematic diagram of the released parking mechanism. 1A is a schematic diagram of the parking mechanism during actuation, FIG. 1B is a schematic diagram of the parking mechanism during deactivation, and FIG. 1C is a schematic diagram of the released parking mechanism. FIG. 11 is a schematic diagram of a cam according to a second embodiment.

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. First, the transmission 1 will be described with reference to FIG. 1. FIG. 1 is a skeleton diagram of the transmission 1 in one embodiment. The transmission 1 includes an input shaft 2 to which the power of an engine or a motor is input, and an output shaft 3 arranged parallel to the input shaft 2, and an output gear 4 is arranged on the output shaft 3. The output shaft 3 outputs torque to wheels 115 of a vehicle 114 (see FIG. 4) such as an automobile through the output gear 4. The intermediate shaft 5 is arranged parallel to the input shaft 2. The input shaft 2 and the output shaft 3 support a first gear 10, a second gear 20, a third gear 30, a fourth gear 40, and a fifth gear 50 that constitute a plurality of gear stages. The input shaft 2, the intermediate shaft 5, and the output shaft 3 support a reverse gear 60 that constitutes a reverse stage.

The first-speed gear 10 includes a fixed gear 11 fixed to the input shaft 2 so as not to rotate relative to the input shaft 2, and an idling gear 12 which is always in mesh with the fixed gear 11 and is fixed to the output shaft 3 so as to rotate relative to the input shaft 2. The second-speed gear 20 includes an idling gear 21 fixed to the input shaft 2 so as to rotate relative to the input shaft 2, and a fixed gear 22 which is always in mesh with the idling gear 21 and is fixed to the output shaft 3 so as not to rotate relative to the input shaft 2. The third-speed gear 30 includes a fixed gear 31 fixed to the input shaft 2 so as not to rotate relative to the input shaft 2, and an idling gear 32 which is always in mesh with the fixed gear 31 and is fixed to the output shaft 3 so as to rotate relative to the input shaft 2.

The fourth-speed gear 40 includes an idling gear 41 fixed to the input shaft 2 so as to be rotatable relative to the input shaft 2, and a fixed gear 42 that is always in mesh with the idling gear 41 and is fixed to the output shaft 3 so as not to be rotatable relative to the input shaft 2. The fifth-speed gear 50 includes an idling gear 51 fixed to the input shaft 2 so as to be rotatable relative to the input shaft 2, and a fixed gear 52 that is always in mesh with the idling gear 51 and is fixed to the output shaft 3 so as not to be rotatable relative to the input shaft 2. The reverse gear 60 includes an idling gear 61 fixed to the input shaft 2 so as to be rotatable relative to the input shaft 2, a fixed gear 62 that is always in mesh with the idling gear 61 and is fixed to the intermediate shaft 5 so as not to be rotatable relative to the input shaft 2, and a fixed gear 63 that is always in mesh with the fixed gear 62 and is fixed to the output shaft 3 so as not to be rotatable relative to the input shaft 2.

The transmission 1 further includes a shift device 70 that selectively couples gears to the input shaft 2 and the output shaft 3. The shift device 70 includes a sleeve 71 that rotates integrally with the output shaft 3, sleeves 72 and 73 that rotate integrally with the input shaft 2, forks 74, 75 and 76 that are respectively arranged on the sleeves 71, 72 and 73, rods 77, 78 and 79 on which the forks 74, 75 and 76 are respectively arranged, and cams 80, 81 and 82 that move the rods 77, 78 and 79 in the axial direction, respectively.

The sleeve 71 is an annular member disposed between the idling gears 12, 32. The axial end faces of the idling gears 12, 32 are provided with first teeth 13, 33 spaced apart from each other in the circumferential direction. The axial end face of the sleeve 71 is provided with second teeth (described later) that mesh with the first teeth 13, 33, respectively.

The sleeve 72 is an annular member disposed between the idling gears 21, 51. The axial end faces of the idling gears 21, 51 are provided with first teeth 23, 53 spaced apart from each other in the circumferential direction. The axial end face of the sleeve 72 is provided with second teeth (described later) that mesh with the first teeth 23, 53, respectively.

The sleeve 73 is an annular member disposed between the idling gears 41, 61. The axial end faces of the idling gears 41, 61 are provided with first teeth 43, 64 spaced apart from each other in the circumferential direction. The axial end face of the sleeve 73 is provided with second teeth (described later) that mesh with the first teeth 43, 64, respectively.

Forks 74, 75, and 76 are disposed on the outer periphery of sleeves 71, 72, and 73, respectively. Rods 77, 78, and 79 on which forks 74, 75, and 76 are disposed are disposed parallel to the input shaft 2. Protrusions 83, 84, and 85 provided on rods 77, 78, and 79, respectively, contact cams 80, 81, and 82, respectively. In this embodiment, the cams 80, 81, and 82 are provided on the outer periphery of a shift drum 86. The shift drum 86 rotates around a central axis 87 parallel to the input shaft 2 by a motor (not shown).

The shift drum 86 rotates based on an operation signal from a shift lever (not shown) or based on an accelerator opening signal and a vehicle speed signal from an accelerator pedal (not shown). When the shift drum 86 rotates, the forks 74, 75, and 76 move in the axial direction via the rods 77, 78, and 79, whose protrusions 83, 84, and 85 contact the cams 80, 81, and 82, respectively. As the forks 74, 75, and 76 move, the sleeves 71, 72, and 73 move in the axial direction. When the second teeth (described later) of the sleeves 71, 72, and 73 mesh with any of the first teeth 13, 23, 33, 43, 53, and 64, the idling gears 12, 21, 32, 41, 51, and 61 are selectively coupled to the input shaft 2 or the output shaft 3.

Figure 2 is a schematic diagram of cams 80, 81, and 82 in the first embodiment. Figure 2 is a part of an exploded view of the outer periphery of the shift drum 86 cut open by a straight line parallel to the central axis 87 (see Figure 1). The shift drum 86 is set to a parking position P, a reverse position R, a neutral position N, a first gear position (1st), and a second gear position (2nd). Third gear and higher positions are not shown in Figure 2.

In the second gear position, the sleeve 72 connects the idling gear 21 (see FIG. 1) to the input shaft 2. In the first gear position, the sleeve 71 connects the idling gear 12 (see FIG. 1) to the output shaft 3. In the neutral position N, the idling gears 12, 21, 32, 41, 51, and 61 rotate freely on the shaft. In the reverse position R, the sleeve 73 connects the idling gear 61 (see FIG. 1) to the input shaft 2. In the parking position P, the sleeve 71 connects the idling gear 12 (see FIG. 1) to the output shaft 3, and the sleeve 72 connects the idling gear 21 (see FIG. 1) to the input shaft 2. The cams 80 and 81 are adjacent in the displacement direction to the locked position L (same as the parking position P) where the idling gears 12 and 21 are both connected to the shaft, and the unlocked position U where the idling gears 12 and 21 rotate freely on the shaft.

Figure 3 is a schematic diagram of the parking mechanism 90. The end face of the sleeve 71 is provided with second teeth 91, 94 protruding in the axial direction. The second teeth 91 mesh with the first teeth 13 of the idling gear 12, and the second teeth 94 mesh with the first teeth 33 of the idling gear 32. The first teeth 13 have a first surface 95 facing one side in the circumferential direction and a second surface 96 facing the other side in the circumferential direction. The second teeth 91 have a third surface 92 facing the other side in the circumferential direction and a fourth surface 93 facing one side in the circumferential direction. When the first teeth 13 and the second teeth 91 mesh with each other, at least a portion of the first surface 95 faces the third surface 92, and at least a portion of the second surface 96 faces the fourth surface 93.

The end face of the sleeve 72 is provided with second teeth 97, 100 protruding in the axial direction. The second teeth 97 mesh with the first teeth 23 of the idling gear 21, and the second teeth 100 mesh with the first teeth 53 of the idling gear 51. The first teeth 23 have a first surface 101 facing one side in the circumferential direction and a second surface 102 facing the other side in the circumferential direction. The second teeth 97 have a third surface 98 facing the other side in the circumferential direction and a fourth surface 99 facing one side in the circumferential direction. When the first teeth 23 and the second teeth 97 mesh with each other, at least a portion of the first surface 101 faces the third surface 98, and at least a portion of the second surface 102 faces the fourth surface 99.

The first surface 95 and the third surface 92 are approximately parallel to a plane including the central axis of the sleeve 71. The second surface 96 and the fourth surface 93 are inclined with respect to a plane including the central axis of the sleeve 71. The second surface 96 is inclined so as to approach the first surface 95 as it approaches the tooth tip. The fourth surface 93 is inclined so as to approach the third surface 92 as it approaches the tooth tip. The angle θ2 between the plane including the central axis of the sleeve 71 and the second surface 96 and the fourth surface 93 is larger than the angle θ1 (almost 0° in this embodiment) between the plane including the central axis of the sleeve 71 and the first surface 95 and the third surface 92. The angles θ1 and θ2 refer to the angle between the part of each surface that comes into contact when the first tooth 13 and the second tooth 91 mesh with each other and the plane including the central axis.

The second surface 96 and the fourth surface 93 generate a thrust force that separates the idling gear 12 and the sleeve 71 in the axial direction in response to a torque in a direction that presses the second surface 96 and the fourth surface 93 against each other. The first surface 95 and the third surface 92 do not generate a thrust force that separates the idling gear 12 and the sleeve 71 in the axial direction when the first surface 95 and the third surface 92 are pressed against each other to transmit torque. The first surface 95 and the third surface 92 transmit a torque in a direction that presses the first surface 95 and the third surface 92 against each other.

Similarly, the first surface 101 and the third surface 98 are approximately parallel to a plane including the central axis of the sleeve 72. The second surface 102 and the fourth surface 99 are inclined with respect to a plane including the central axis of the sleeve 72. The second surface 102 is inclined so as to approach the first surface 101 as it approaches the tooth tip. The fourth surface 99 is inclined so as to approach the third surface 98 as it approaches the tooth tip. The angle θ2 between the plane including the central axis of the sleeve 72 and the second surface 102 and the fourth surface 99 is greater than the angle θ1 (not shown in this embodiment because it is approximately 0°) between the plane including the central axis of the sleeve 72 and the first surface 101 and the third surface 98. The angles θ1 and θ2 refer to the angle between the part of each surface that comes into contact when the first tooth 23 and the second tooth 97 mesh with each other and the plane including the central axis.

The second surface 102 and the fourth surface 99 generate a thrust force that separates the idling gear 21 and the sleeve 72 in the axial direction in response to a torque in a direction pressing the second surface 102 and the fourth surface 99 against each other. The first surface 101 and the third surface 98 do not generate a thrust force that separates the idling gear 21 and the sleeve 72 in the axial direction when the first surface 101 and the third surface 98 press against each other to transmit torque. The first surface 101 and the third surface 98 transmit a torque in a direction pressing the first surface 101 and the third surface 98 against each other.

A spring 112 is disposed between the fork 74 and the rod 77, which uses elastic force to move the fork 74 in a direction away from the idling gear 12. Similarly, a spring 113 is disposed between the fork 75 and the rod 78, which uses elastic force to move the fork 75 in a direction away from the idling gear 21. The structure in which the spring 113 is disposed between the fork 75 and the rod 78 is similar to the structure in which the spring 112 is disposed between the fork 74 and the rod 77, and therefore the same reference numerals are used and the description is omitted.

A tube 103 is disposed on the rod 77, surrounding the rod 77. An elongated hole 104 extending in the axial direction of the tube 103 penetrates the tube 103 in the thickness direction. A gap is provided between the outer periphery of the rod 77 and the inner periphery of the tube 103. One end of the tube 103 is provided with a convex portion 105 (stopper) that protrudes radially inward. A pin 106 that protrudes radially outward is disposed on the rod 77. The pin 106 is inserted in the elongated hole 104. The thickness of the pin 106 is smaller than the axial length of the elongated hole 104.

The rod 77 has two grooves spaced apart in the axial direction, and the retaining rings 107, 108 are fixed in the grooves. Washers 109, 110, each with an outer diameter larger than that of the retaining rings 107, 108, are arranged on the rod 77 on the inner side of the retaining rings 107, 108 in the axial direction. The washers 109, 110 are arranged on the inner side of the cylinder 103 with an axial gap between them. The washer 109 is located on the inner side of the protrusion 105 in the axial direction. A cylindrical spacer 111 is interposed between the washer 110 and the pin 106.

A spring 112 is disposed between the washers 109 and 110. In this embodiment, the spring 112 is a compression coil spring. Since the distance between the washers 109 and 110 is shorter than the free length of the spring 112, a preload is applied to the spring 112. The washers 109 and 110 are pressed against the retaining rings 107 and 108, respectively, by the restoring force of the preloaded spring 112. In the neutral position of the shift drum 86, the spring 112 presses the pin 106 against the edge 104a on one side of the axial direction of the long hole 104, and presses the washer 109 against the protrusion 105, by the restoring force. When the rod 77 is displaced in the axial direction from the neutral position so that the sleeve 71 approaches the idler gear 12, the pin 106 attached to the rod 77 presses the edge 104a of the long hole 104, causing the sleeve 71 to be displaced in the axial direction via the fork 74 attached to the tube 103.

When starting the vehicle 114, the sleeve 71 is moved from the neutral position toward the idling gear 12, and the second tooth 91 of the sleeve 71 meshes with the first tooth 13 of the idling gear 12. This establishes first gear. When power is input to the input shaft 2 to press the first surface 95 against the third surface 92, a torque (drive torque) in a direction pressing the first surface 95 against the third surface 92 is transmitted from the idling gear 12 to the sleeve 71, causing the output shaft 3 to rotate.

When shifting up from first to second gear, the sleeve 72 moves from the neutral position toward the idler gear 21, and the second tooth 97 of the sleeve 72 meshes with the first tooth 23 of the idler gear 21. When the first surface 101 and the third surface 98 are pressed against each other by the rotation of the sleeve 72, the idler gear 21 rotates faster than the idler gear 12, so that the first gear 10 is in a coast state and the second gear 20 is in a drive state.

In the second gear 20, the first surface 101 and the third surface 98 are pressed together to transmit the drive torque. In the first gear 10, the second surface 96 and the fourth surface 93 are pressed together, and a thrust force is generated that moves the idling gear 12 and the sleeve 71 apart in the axial direction in response to the coasting torque. When the first tooth 13 of the idling gear 12 and the second tooth 91 of the sleeve 71 are disengaged, the second gear is established. The transmission 1 can achieve a so-called seamless shift, which reduces interruptions in the torque of the output shaft 3 when shifting up.

Next, the operation of the parking mechanism 90 will be described. First, with reference to Figures 4 and 5, the parking mechanism 90 when the vehicle 114 is parked on a downhill slope will be described. Figures 4(a) and 5(a) are schematic diagrams of the parking mechanism 90 in operation, Figures 4(b) and 5(b) are schematic diagrams of the parking mechanism 90 while it is being released, and Figures 4(c) and 5(c) are schematic diagrams of the parking mechanism 90 when it has been released.

When the parking mechanism 90 is operated, the cams 80 and 81 are rotated to set the projections 83 and 84 to the lock position L. As a result, the second tooth 91 of the sleeve 71 meshes with the first tooth 13 of the idling gear 12 as shown in FIG. 4(a), and the second tooth 97 of the sleeve 72 meshes with the first tooth 23 of the idling gear 21 as shown in FIG. 5(a). When the wheel 115 rotates due to gravity acting on the vehicle 114, the third surface 98 of the second tooth 97 presses against the first surface 101 of the first tooth 23, and the fourth surface 93 of the second tooth 91 presses against the second surface 96 of the first tooth 13.

When the fourth surface 93 and the second surface 96 are pressed against each other, a thrust force is generated that separates the idling gear 12 and the sleeve 71 in the axial direction, but the fork 74 arranged on the sleeve 71 is attached to the tube 103, and the edge 104a of the long hole 104 of the tube 103 hits the pin 106 of the rod 77, so the sleeve 71 cannot separate from the idling gear 12 unless the rod 77 moves. Therefore, the wheel 115 cannot rotate due to the double meshing of the first-speed gear 10 and the second-speed gear 20.

When the parking mechanism 90 is released, as shown in FIG. 4(b), the cams 80, 81 are rotated to move the projections 83, 84 from the locked position L to the unlocked position U. The thrust force that separates the idling gear 12 and the sleeve 71 in the axial direction, generated when the fourth surface 93 and the second surface 96 are pressed against each other, assists the displacement of the projection 83 and the fork 74 that accompanies the rotation of the cam 80. Thus, in conjunction with the displacement of the rod 77, the sleeve 71 moves in a direction that disengages the first tooth 13 and the second tooth 91 of the idling gear 12.

5(b), the third surface 98 of the second tooth 97 of the sleeve 72 is pressed against the first surface 101 of the first tooth 23 of the idling gear 21, so that the frictional force acting between the third surface 98 and the first surface 101 is large and the sleeve 72 cannot move even when the cam 81 rotates. The elastic force of the spring 113 interposed between the fork 75 and the rod 78 is smaller than the frictional force acting between the third surface 98 and the first surface 101, so that as the rod 78 is displaced by the rotation of the cam 81, the spring 113 is compressed and stores elastic energy.

As shown in FIG. 4(c), when the cams 80 and 81 are rotated and the protrusions 83 and 84 approach the unlocked position U, the first tooth 13 and the second tooth 91 of the idling gear 12 are disengaged as the sleeve 71 moves. Since the idling gear 12 rotates freely on the output shaft 3, the input shaft 2, which was constrained by the fixed gear 11 meshing with the idling gear 12, becomes free. Then, the frictional force acting on the third surface 98 of the second tooth 97 of the sleeve 72 and the first surface 101 of the first tooth 23 of the idling gear 21 becomes smaller. Since the frictional force at this time is smaller than the restoring force when the elastic energy stored in the spring 113 is released, the sleeve 72 moves due to the restoring force of the spring 113, and the first tooth 23 and the second tooth 97 of the idling gear 21 are disengaged (see FIG. 5(c)). This releases the parking mechanism 90. When the pin 206 hits the edge 104a of the slot 104, the extension of the spring 113 stops.

6 and 7, the parking mechanism 90 when the vehicle 114 is parked on an uphill slope will be described. Figures 6(a) and 7(a) are schematic diagrams of the parking mechanism 90 in operation, Figures 6(b) and 7(b) are schematic diagrams of the parking mechanism 90 while it is being deactivated, and Figures 6(c) and 7(c) are schematic diagrams of the parking mechanism 90 in a deactivated state.

When the parking mechanism 90 is operated, the cams 80 and 81 are rotated to set the projections 83 and 84 to the lock position L. As a result, the second tooth 97 of the sleeve 72 meshes with the first tooth 23 of the idling gear 21 as shown in FIG. 6(a), and the second tooth 91 of the sleeve 71 meshes with the first tooth 13 of the idling gear 12 as shown in FIG. 7(a). When the wheel 115 rotates due to gravity acting on the vehicle 114, the third surface 92 of the second tooth 91 presses against the first surface 95 of the first tooth 13, and the fourth surface 99 of the second tooth 97 presses against the second surface 102 of the first tooth 23.

When the fourth surface 99 and the second surface 102 are pressed against each other, a thrust force is generated that separates the idling gear 21 and the sleeve 72 in the axial direction, but the fork 75 arranged on the sleeve 72 is attached to the tube 103, and the edge 104a of the long hole 104 of the tube 103 hits the pin 106 of the rod 78, so the sleeve 72 cannot separate from the idling gear 21 unless the rod 78 moves. Therefore, the double meshing of the first-speed gear 10 and the second-speed gear 20 prevents the wheel 115 from rotating.

When the parking mechanism 90 is released, as shown in FIG. 6(b), the cams 80, 81 are rotated to move the projections 83, 84 from the locked position L to the unlocked position U. The thrust force that separates the idling gear 21 and the sleeve 72 in the axial direction, generated by the fourth surface 99 and the second surface 102 being pressed against each other, assists the displacement of the projection 84 and the fork 75 that accompanies the rotation of the cam 81. Thus, in conjunction with the displacement of the rod 78, the sleeve 72 moves in a direction that disengages the first tooth 23 and the second tooth 97 of the idling gear 21.

7(b), the third surface 92 of the second tooth 91 of the sleeve 71 and the first surface 95 of the first tooth 13 of the idling gear 12 are pressed against each other, so the frictional force acting between the third surface 92 and the first surface 95 is large, and the sleeve 71 cannot move even when the cam 80 rotates. The elastic force of the spring 112 interposed between the fork 74 and the rod 77 is smaller than the frictional force acting between the third surface 92 and the first surface 95, so that the spring 112 compresses and accumulates elastic energy as the rod 77 is displaced by the rotation of the cam 80.

As shown in FIG. 6(c), when the cams 80 and 81 are rotated and the protrusions 83 and 84 approach the unlocked position U, the first tooth 23 and the second tooth 97 of the idling gear 21 are disengaged as the sleeve 72 moves. Since the idling gear 21 rotates freely on the input shaft 2, the output shaft 3, which was constrained by the fixed gear 22 meshing with the idling gear 21, becomes free. Then, the frictional force acting on the third surface 92 of the second tooth 91 of the sleeve 71 and the first surface 95 of the first tooth 13 of the idling gear 12 becomes smaller. Since the frictional force at this time is smaller than the restoring force when the elastic energy accumulated in the spring 112 is released, the sleeve 71 moves due to the restoring force of the spring 112, and the first tooth 13 and the second tooth 91 of the idling gear 12 are disengaged (see FIG. 7(c)). This releases the parking mechanism 90.

The parking mechanism 90 has second surfaces 96, 102 and fourth surfaces 93, 99 that generate thrust to move the idling gears 12, 21 and the sleeves 71, 72 axially apart, so that the operation of the parking mechanism 90 can be released with a small force even when the vehicle 114 is parked on an uphill or downhill slope. This allows the motor (not shown) that rotates the cams 80, 81 to be made smaller. In addition, the energy consumed by the motor when rotating the cams 80, 81 to release the parking mechanism 90 can be reduced.

Because angle θ2 is greater than angle θ1, when the parking mechanism 90 is released, the two teeth against which the second surface 96, 102 and the fourth surface 93, 99 are pressed can be released first while maintaining the engagement due to the frictional force acting on the first surface 95, 101 and the third surface 92, 98. This prevents the force applied by the cams 80, 81 to the forks 74, 75 from being dispersed when the parking mechanism 90 is released. When one of the teeth is released from the engagement, the other tooth against which the first surface 95, 101 and the third surface 92, 98 are pressed can be easily released. This allows the parking mechanism 90 to be released smoothly regardless of the state of the vehicle 114 (uphill or downhill).

Since the cams 80, 81 are provided on the shift drum 86, the number of parts can be reduced and the transmission 1 can be made smaller than in the case where a cam for the parking mechanism 90 is provided separately from the shift drum 86.

In the parking mechanism 90, springs 112, 113 are interposed between the rods 77, 78 and the forks 74, 75, so that the elastic energy accumulated in the locked position L can be released and the two teeth can be disengaged by displacement from the locked position L to the unlocked position U caused by the rotation of the cams 80, 81 in one direction. This simplifies the operation of releasing the parking mechanism 90.

The second embodiment will be described with reference to FIG. 8. In the first embodiment, springs 112, 113 are interposed between rods 77, 78 and forks 74, 75, and the springs 112, 113 are elastically deformed to cause relative axial displacement between rods 77, 78 and forks 74, 75. In contrast, the second embodiment will be described with respect to a case where springs 112, 113 are not present and forks 74, 75 are connected to rods 77, 78, respectively. In the second embodiment, the axial displacement of rods 77, 78 is directly connected to the axial displacement of forks 74, 75. In the second embodiment, the same parts as those described in the first embodiment are designated by the same reference numerals and will not be described below.

Figure 8 is a schematic diagram of cams 120, 121, and 122 in the second embodiment. The cams 120, 121, and 122 are provided on the outer periphery of a shift drum 123. The shift drum 123 is arranged in place of the shift drum 86 of the parking mechanism 90 in the first embodiment. The shift drum 123 rotates around a central axis 87 parallel to the input shaft 2 (see Figure 1) by a motor (not shown). Figure 8 is a part of a development view in which the outer periphery of the shift drum 123 is cut open by a straight line parallel to the central axis 87. A current sensor (not shown) that detects the current flowing through the circuit is arranged in the circuit of the motor that rotates the shift drum 123.

When the motor is operated and the shift drum 123 rotates, the forks 74, 75, and 76 move in the axial direction via the rods 77, 78, and 79 (see FIG. 1) whose protrusions 83, 84, and 85 contact the cams 120, 121, and 122, respectively. The shift drum 123 has a parking position P, a reverse position R, a neutral position N, a first gear position (1st), and a second gear position (2nd). In FIG. 8, the third and higher gear positions are not shown.

Cams 120, 121 are adjacent to a lock position L (same as parking position P) where both idling gears 12, 21 (see FIG. 3) are connected to the shaft, and a first position U1 where the second tooth 91 of sleeve 71 disengages from the first tooth 13 of idling gear 12, and are adjacent to a second position U2 where the second tooth 97 of sleeve 72 disengages from the first tooth 23 of idling gear 21. The first position U1 and the second position U2 are located on both sides of the lock position L in the displacement direction of cams 120, 121. The cam curves of cams 120, 121 near lock position L are shifted from each other in the displacement direction of cams 120, 121.

When the parking mechanism 90 is deactivated, it first displaces the cams 120, 121 so that the projections 83, 84 move from the lock position L to the first position U1. If the second tooth 91 of the sleeve 71 and the first tooth 13 of the idling gear 12 do not disengage, it displaces the cams 120, 121 in the opposite direction so that the projections 83, 84 move to the second position U2 via the lock position L. Conversely, it is also possible to displace the cams 120, 121 so that the projections 83, 84 move to the second position U2 via the lock position L, and then displace the cams 120, 121 so that the projections 83, 84 move from the lock position L to the first position U1.

In a vehicle 114 parked on a downward slope (see Figs. 4(a) to 4(c)), when the cams 120 and 121 are displaced so that the projections 83 and 84 move from the lock position L to the first position U1, the rod 77 is displaced to disengage the second tooth 91 of the sleeve 71 from the first tooth 13 of the idling gear 12. Because the second surface 96 of the first tooth 13 and the fourth surface 93 of the second tooth 91 are pressed against each other, a thrust force acts to separate the idling gear 12 and the sleeve 71 in the axial direction, assisting the displacement of the projection 83 and the fork 74 accompanying the rotation of the cam 120. As the rod 77 is displaced, the sleeve 71 is also displaced, and the first tooth 13 of the idling gear 12 is disengaged from the second tooth 91. When the cams 120 and 121 are further displaced in the same direction, the first tooth 23 of the idling gear 21 is also disengaged from the second tooth 97.

In a vehicle 114 parked on an uphill slope (see FIG. 7(a)), when the cams 120, 121 are displaced so that the protrusions 83, 84 move from the locked position L to the first position U1, the rod 77 is displaced, attempting to disengage the second tooth 91 of the sleeve 71 from the first tooth 13 of the free-wheeling gear 12. Because the first surface 95 of the first tooth 13 and the third surface 92 of the second tooth 91 are pressed against each other, the large frictional force acting between the first surface 95 and the third surface 92 prevents the cams 120, 121 from being displaced. When the motor is turned to displace the cams 120, 121, a large current flows through the motor circuit.

When the current value detected by the current sensor disposed in the motor circuit exceeds a predetermined value, the parking mechanism 90 displaces the cams 120 and 121 in the opposite direction so that the projections 83 and 84 move to the second position U2 via the lock position L. This displaces the rod 78, attempting to disengage the second tooth 97 of the sleeve 72 from the first tooth 23 of the idling gear 21. Since the second surface 102 of the first tooth 23 and the fourth surface 99 of the second tooth 97 are pressed against each other, a thrust force acts to separate the idling gear 21 and the sleeve 72 in the axial direction, assisting the displacement of the projection 84 and the fork 75 accompanying the rotation of the cam 121. The sleeve 72 is also displaced with the displacement of the rod 78, and the first tooth 23 of the idling gear 21 is disengaged from the second tooth 97. When the cams 120 and 121 are further displaced in the same direction, the first tooth 13 of the idling gear 12 is also disengaged from the second tooth 91.

According to this embodiment, as in the first embodiment, the motor that displaces the cams 120 and 121 can be made smaller. Furthermore, since the springs 112 and 113, etc., that are interposed between the rods 77 and 78 and the forks 74 and 75 to release the parking mechanism 90 are not required, the mechanism can be simplified.

Although the present invention has been described above based on an embodiment, the present invention is not limited to this embodiment, and it is easily understood that various improvements and modifications are possible within the scope of the present invention. For example, the number and arrangement of gear stages of the transmission 1, the shafts on which the idling gears and fixed gears are arranged, and the shapes of the cams 80, 81, 120, and 121 can be set as appropriate.

The transmission 1 described in the embodiment is one example. Another example of a transmission is a so-called dual clutch transmission, which has first and second clutches arranged coaxially with the input shaft, with the first clutch for odd-numbered gears and the second clutch for even-numbered gears.

In the embodiment, a case where the first gear 10 and the second gear 20 are simultaneously established at the parking position P has been described, but this is not limited to this. It is of course possible to set the parking position P to a position where two arbitrary gear trains with different gear ratios are established, such as the first gear 10 and the fourth gear 40, or the second gear 20 and the third gear 30. This is because, as in the embodiment, the wheels 115 cannot rotate due to the double meshing.

In the embodiment, the first surface 95, 101 of the first tooth 13, 23 and the third surface 92, 98 of the second tooth 91, 97 are parallel to a plane including the central axis of the sleeve 71, 72, but this is not necessarily limited to this. When the first surface 95, 101 of the first tooth 13, 23 and the third surface 92, 98 of the second tooth 91, 97 are pressed against each other to transmit torque, the resultant force of the axial component of the force due to the torque and the axial component of the frictional force acting on the first surface 95, 101 and the third surface 92, 98 should not act in a direction that moves the sleeve 71, 72 away from the idling gear 12, 21. If this relationship is satisfied, the first surface 95, 101 and the third surface 92, 98 may be inclined with respect to a plane including the central axis of the sleeve 71, 72.

In the embodiment, the cams 80, 81, 120, and 121 are provided on the shift drums 86 and 123, but this is not necessarily limited to this. Cams 80, 81, 120, and 121 for the parking mechanism 90 may be provided separately from the shift drums 86 and 123.

In the embodiment, the case where the cams 80, 81, 120, and 121 are displaced by a motor has been described, but this is not necessarily limited to this. It is of course possible to provide a lever that displaces the cams 80, 81, 120, and 121, and to displace the cams 80, 81, 120, and 121 by manually operating the lever.

In the first embodiment, the springs 112 and 113 are compression coil springs, but this is not necessarily limited to this. It is of course possible to use elastic bodies other than coil springs for the springs 112 and 113.

In the first embodiment, a case where a long hole 104 is provided in the cylinder 103 and a pin 106 is provided in the rods 77 and 78 is described, but this is not necessarily limited to this. Conversely, it is of course possible to provide a long hole in the rods 77 and 78 and provide a pin in the cylinder 103.

In the second embodiment, a current sensor is disposed to detect the current flowing in the circuit of the motor that operates the cams 120, 121, and whether or not the meshing between the second tooth 91 of the sleeve 71 and the first tooth 13 of the idling gear 12 has been determined based on the detection result of the current sensor, but this is not necessarily limited to this. It is of course possible to determine whether or not the meshing between the second tooth 91 of the sleeve 71 and the first tooth 13 of the idling gear 12 has been determined based on the detection result of another sensor. Examples of the other sensor include a rotation sensor for the cams 120, 121 and a position sensor that detects the axial position of the sleeve 71.

In the second embodiment, an acceleration sensor mounted on the vehicle may be used to determine whether the vehicle is parked on a downhill or uphill slope, and the following (1) or (2) may be selected to quickly release the parking mechanism 90. (1) The cams 120, 121 are displaced so that the protrusions 83, 84 move to the first position U1, and then the cams 120, 121 are displaced so that the protrusions 83, 84 move to the second position U2. (2) The cams 120, 121 are displaced so that the protrusions 83, 84 move to the second position U2, and then the cams 120, 121 are displaced so that the protrusions 83, 84 move to the first position U1.

1 Transmission 2 Input shaft (shaft)
3 Output shaft (shaft)
11 Fixed gear (first fixed gear)
12 Idler gear (first idler gear)
13 First tooth 21 Idler gear (first idler gear)
22 Fixed gear (second fixed gear)
23 First tooth 71 Sleeve (first sleeve)
72 Sleeve (second sleeve)
74 Fork (first fork)
75 Fork (Second Fork)
80, 120 Cam (first cam)
81, 121 Cam (second cam)
90 Parking mechanism 91, 97 Second teeth 92, 98 Third surface 93, 99 Fourth surface 95, 101 First surface 96, 102 Second surface 112 Spring (first spring)
113 Spring (second spring)
114 Vehicle 115 Wheel L Locked position U Unlocked position U1 First position U2 Second position

Claims (3)

Axes arranged parallel to each other;
a first and a second idler gear, each having a first tooth, disposed on the shaft so as to be rotatable relative to the shaft and immovable in the axial direction;
a first fixed gear and a second fixed gear which are arranged on the shaft so as not to rotate relative to the shaft and which mesh with the first and second idling gears, respectively;
a first sleeve and a second sleeve, each of which has second teeth meshing with the first teeth, disposed on the shaft so as to be non-rotatable relative to the shaft and movable in the axial direction;
first and second forks disposed in the first and second sleeves, respectively;
a first rod and a second rod on which the first and second forks are disposed, respectively;
A parking mechanism for a vehicle including a transmission having a first and a second cam that move the first and the second rods in an axial direction,
a lock position in which the first and second cams bring about a state in which the second teeth of the first sleeve mesh with the first teeth of the first idler gear and the second teeth of the second sleeve mesh with the first teeth of the second idler gear;
an unlocked position in which at least one of meshing between the second teeth of the first sleeve and the first teeth of the first idler gear and meshing between the second teeth of the second sleeve and the first teeth of the second idler gear is released,
The first tooth includes a first surface facing one side in a circumferential direction and a second surface facing the other side in the circumferential direction,
the second tooth includes a third surface facing the first surface and a fourth surface facing the second surface in the locked position;
the first surface and the third surface transmit a torque in a direction pressing the first surface against the third surface;
the second surface and the fourth surface generate a thrust force that moves the first tooth and the second tooth apart in the axial direction in response to a torque in a direction pressing the second surface and the fourth surface against each other ,
the unlocked position is a first position where the second teeth of the first sleeve and the first teeth of the first idler gear are disengaged from each other;
a second position in which the second teeth of the second sleeve and the first teeth of the second idler gear are disengaged from each other;
A parking mechanism in which the first position and the second position are located on either side of the lock position in a displacement direction of the first and second cams . Axes arranged parallel to each other;
a first and a second idler gear, each having a first tooth, disposed on the shaft so as to be rotatable relative to the shaft and immovable in the axial direction;
a first fixed gear and a second fixed gear which are arranged on the shaft so as not to rotate relative to the shaft and which mesh with the first and second idling gears, respectively;
a first sleeve and a second sleeve, each of which has second teeth meshing with the first teeth, disposed on the shaft so as to be non-rotatable relative to the shaft and movable in the axial direction;
first and second forks disposed in the first and second sleeves, respectively;
a first rod and a second rod on which the first and second forks are disposed, respectively;
A parking mechanism for a vehicle including a transmission having a first and a second cam that move the first and the second rods in an axial direction,
a first spring interposed between the first rod and the first fork;
a second spring interposed between the second rod and the second fork;
a lock position in which the first and second cams bring about a state in which the second teeth of the first sleeve mesh with the first teeth of the first idler gear and the second teeth of the second sleeve mesh with the first teeth of the second idler gear;
an unlocked position in which at least one of meshing between the second teeth of the first sleeve and the first teeth of the first idler gear and meshing between the second teeth of the second sleeve and the first teeth of the second idler gear is released,
The first tooth includes a first surface facing one side in a circumferential direction and a second surface facing the other side in the circumferential direction,
the second tooth includes a third surface facing the first surface and a fourth surface facing the second surface in the locked position;
the first surface and the third surface transmit a torque in a direction pressing the first surface against the third surface;
the second surface and the fourth surface generate a thrust force that moves the first tooth and the second tooth apart in the axial direction in response to a torque in a direction pressing the second surface and the fourth surface against each other ,
A parking mechanism in which the first or second spring releases accumulated elastic energy as the spring is displaced from the locked position to the unlocked position, thereby disengaging the second tooth of the first sleeve from the first tooth of the first idling gear, or disengaging the second tooth of the second sleeve from the first tooth of the second idling gear. 3. The parking mechanism according to claim 1, wherein an angle θ2 (acute angle side) between a plane including a central axis of a shaft on which the first teeth and the second teeth are provided and the second and fourth surfaces is greater than an angle θ1 (acute angle side) between the plane and the first and third surfaces.

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