JP7483307B2 - Gear Unit - Google Patents

Description

The present invention relates to a transmission unit including a torque converter and a transmission.

In vehicles equipped with an engine as a driving source, the engine's power is transmitted to the drive wheels via a transmission. Engines can be mounted either vertically, with the crankshaft facing vertically relative to the front-to-rear direction of the vehicle body, or horizontally, with the crankshaft facing horizontally. In vehicles that use a front-engine front-wheel-drive (FF) layout, for example, the engine is often mounted horizontally, in order to increase the vehicle interior length by reducing the size of the engine compartment in the front-to-rear direction. On the other hand, in vehicles that use a front-engine rear-wheel-drive (FR) layout, the engine is sometimes mounted vertically due to the ease of transmitting power to the rear wheels, which are the drive wheels.

A vertically mounted CVT (Continuously Variable Transmission) has already been provided as a transmission for vehicles with a vertically mounted engine. In a vertically mounted CVT, an input shaft to which the engine power is input is arranged vertically relative to the front-rear direction of the vehicle body. In one example of a vertically mounted CVT, an input shaft and an output shaft that outputs power to a propeller shaft are arranged on the same axis, and a primary shaft is arranged on the same axis as the input shaft and the output shaft between the input shaft and the output shaft (see, for example, Patent Document 1). The input shaft and the primary shaft are connected so that power can be transmitted, and the power input from the engine to the input shaft is transmitted from the input shaft to the primary shaft. A secondary shaft is arranged parallel to the primary shaft with a gap therebetween, and an endless belt is wound between a primary pulley supported by the primary shaft and a secondary pulley supported by the secondary shaft. As a result, the power transmitted from the input shaft to the primary shaft is transmitted from the primary pulley to the belt, and from the belt to the secondary pulley. In addition, an intermediate shaft is provided that extends parallel to the secondary shaft at a distance, and the power transmitted to the secondary pulley is transmitted from the secondary shaft to the intermediate shaft via gears, and from the intermediate shaft to the output shaft via gears.

JP 2012-192855 A

However, during the development process of a new vehicle with a FR layout in which the engine is mounted longitudinally, it became clear that the conventional longitudinal CVT structure could not be used for the new vehicle.

The object of the present invention is to provide a transmission unit including a transmission with a new structure that differs from that of conventional longitudinally mounted CVTs.

To achieve the above object, the transmission unit of the present invention includes a torque converter, an input shaft to which power from a drive source is input via the torque converter, an output shaft arranged coaxially with the input shaft and spaced apart from the input shaft in the axial direction of the input shaft, and a continuously variable transmission mechanism that is provided on a power transmission path between the input shaft and the output shaft, has a primary shaft and a secondary shaft each extending parallel to the input shaft, and transmits power from the primary shaft to the secondary shaft at a variable speed, and the vertical positions of the primary shaft and secondary shaft are between the uppermost and lowermost positions of the torque converter.

With this configuration, the vertical size of the continuously variable transmission mechanism is reduced to the extent that the vertical positions of the primary shaft and secondary shaft fit between the uppermost and lowermost positions of the torque converter. Therefore, even in vehicles with low-floor interiors, such as commercial vehicles, it is possible to mount a transmission unit on the vehicle while ensuring the vehicle's minimum ground clearance.

In addition, by reducing the vertical size of the continuously variable transmission mechanism, the size of the transmission unit can be reduced. By reducing the size of the transmission unit, the weight of the transmission unit can be reduced, which in turn improves the fuel efficiency of the vehicle in which the transmission is installed. In addition, the cost can be reduced by reducing the size of the transmission unit.

The transmission unit may further include a reverse shaft that extends parallel to the input shaft, receives power from the input shaft, and transmits the power to the secondary shaft. In this case, it is preferable that the reverse shaft is positioned between the uppermost and lowermost positions of the torque converter in the vertical direction.

Even if the configuration includes a reverse shaft, the vertical size of the continuously variable transmission mechanism can be reduced.

The present invention provides a longitudinally mounted CVT4 with a new structure that differs from conventional longitudinally mounted CVTs, and makes it possible to mount a transmission unit including a longitudinally mounted CVT on a vehicle, such as a commercial vehicle, with a low-floor interior while still ensuring the vehicle's minimum ground clearance.

1 is a cross-sectional view showing a configuration of a speed change unit according to one embodiment of the present invention. 2 is an enlarged cross-sectional view of a part of the transmission unit shown in FIG. 1 . 13 is a view of the inside of the second case of the transmission unit as seen from the rear side (the side opposite to the engine side). FIG. FIG. 2 is a skeleton diagram showing the configuration of a vertically mounted CVT and a power transmission path in the vertically mounted CVT.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

<Gear change unit>
Fig. 1 is a cross-sectional view showing the configuration of a speed change unit 1 according to one embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view showing a part of the speed change unit 1 extracted from Fig. 1. Note that hatching representing a cross section is omitted in the cross-sectional views from Fig. 1 onwards.

The transmission unit 1 is a unit that is mounted on a vehicle and changes the speed of the power generated by an engine (not shown) that serves as a driving source for traveling. The vehicle employs a FR layout, and the engine is mounted vertically with the crankshaft oriented vertically relative to the front-to-rear direction of the vehicle body. The transmission unit 1 includes a torque converter 3 and a vertically mounted CVT 4 within a unit case 2 that forms the outer shell.

<Unit case>
The unit case 2 is divided into three parts, a first case 11, a second case 12, and a third case 13. The first case 11, the second case 12, and the third case 13 are made of, for example, an aluminum alloy and are cast by a die casting method. The first case 11, the second case 12, and the third case 13 are arranged in this order from the front side (engine side) and are integrated by fastening the first case 11 and the second case 12 with bolts (not shown) and fastening the second case 12 and the third case 13 with bolts 14. The torque converter 3 is housed in the first case 11, and the vertically mounted CVT 4 is housed in the second case 12 and the third case 13.

<Torque converter>
The torque converter 3 includes a front cover 21 , a pump impeller 22 , a turbine hub 23 , a turbine runner 24 , a lock-up mechanism 25 , and a stator 26 .

The front cover 21 extends in a generally circular disk shape centered on a rotation axis that extends in the longitudinal direction of the vehicle (body), and its outer peripheral end is bent toward the rear side, which is the side opposite the engine (the side toward the continuously variable transmission 42 described below). The center of the front cover 21 bulges forward. The crankshaft of the engine is connected to this bulging portion so that it cannot rotate relative to the engine.

The pump impeller 22 is disposed on the vertically mounted CVT 4 side of the front cover 21. The outer peripheral end of the pump impeller 22 is connected to the outer peripheral end of the front cover 21 and is arranged so as to be rotatable integrally with the front cover 21 about the rotation axis. A plurality of blades 27 are arranged radially on the inner surface of the pump impeller 22.

The turbine hub 23 is disposed between the front cover 21 and the pump impeller 22.

The turbine runner 24 is fixed to the turbine hub 23. A number of blades 28 are arranged radially on the surface of the turbine runner 24 facing the pump impeller 22.

The lockup mechanism 25 includes a lockup piston 31 and a damper mechanism 32.

The lock-up piston 31 is generally annular, and its inner peripheral end is fitted onto the turbine hub 23, and is positioned between the front cover 21 and the turbine runner 24. When the hydraulic pressure of the engagement-side oil chamber 33 on the turbine runner 24 side relative to the lock-up piston 31 is higher than the hydraulic pressure of the release-side oil chamber 34 on the front cover 21 side, the lock-up piston 31 moves toward the front cover 21 side due to the pressure difference. When the lock-up piston 31 is pressed against the front cover 21, the pump impeller 22 and the turbine runner 24 are directly connected (lock-up on). Conversely, when the hydraulic pressure of the release-side oil chamber 34 is higher than the hydraulic pressure of the engagement-side oil chamber 33, the lock-up piston 31 moves toward the turbine runner 24 side due to the pressure difference. When the lock-up piston 31 is separated from the front cover 21, the direct connection between the pump impeller 22 and the turbine runner 24 is released (lock-up off).

The damper mechanism 32 is a mechanism for damping vibrations from the engine when the pump impeller 22 and the turbine runner 24 are directly connected.

The stator 26 is disposed between the pump impeller 22 and the turbine runner 24.

When the engine torque rotates the pump impeller 22 in the lock-up off state, oil flows from the pump impeller 22 toward the turbine runner 24. This oil flow is received by the blades 28 of the turbine runner 24, causing the turbine runner 24 to rotate. At this time, the torque converter 3 acts as an amplifier, and a torque greater than the engine torque is generated in the turbine runner 24.

<Vertical CVT>
The vertically mounted CVT 4 includes an input shaft 41, a continuously variable transmission mechanism 42, a reverse transmission mechanism 43, and an output shaft 44. The vertically mounted CVT 4 is disposed such that the input shaft 41 is oriented vertically and extends in the front-rear direction of the vehicle.

The input shaft 41 is formed as a hollow shaft and extends along the rotation axis of the torque converter 3. The front end of the input shaft 41 is inserted into the torque converter 3 and is spline-fitted with the turbine hub 23.

The axial center of the input shaft 41 is rotatably supported by the first case 11 via a bearing 45.

A mechanical oil pump 46 is disposed on the rear side (opposite the engine side) of the input shaft 41. The oil pump 46 includes a pump case 47 and a pump cover 48 that is overlaid on the pump case 47. The pump case 47 and the pump cover 48 are fastened by a number of bolts and held in place by the second case 12. A pump gear 49 is housed in the space enclosed by the pump case 47 and the pump cover 48.

The pump case 47 is disposed forward of the pump cover 48. As shown in FIG. 2, a circular recess 51 recessed toward the rear is formed at the front end of the pump case 47. The rear end of the input shaft 41 is inserted into the recess 51. A needle bearing 52 is interposed between the circumferential surface of the input shaft 41 and the inner circumferential surface of the recess 51, and a thrust bearing 53 is interposed between the end face of the input shaft 41 and the bottom surface of the recess 51. As a result, the rear end of the input shaft 41 is rotatably supported by the pump case 47 via the needle bearing 52 and the thrust bearing 53.

As shown in FIG. 1, one end of the pump shaft 54 is connected to the pump gear 49 in a manner that prevents the pump shaft 54 from rotating relative to the pump gear 49. The pump shaft 54 penetrates the center of the recess 51, protrudes forward from the pump case 47, and is inserted into the hollow portion of the input shaft 41 with a gap between it and the inner peripheral surface of the input shaft 41. The front end of the pump shaft 54 is inserted into the forward bulging portion of the center of the front cover 21 of the torque converter 3, and is connected to the front cover 21 in a manner that prevents the pump shaft 54 from rotating relative to the front cover 21. As a result, when the front cover 21 rotates due to the power of the engine, the pump shaft 54 and the pump gear 49 rotate together with the front cover 21, and oil pressure is generated from the oil pump 46.

The input shaft 41 is rotatably supported by the first case 11 via a bearing 45, and rotatably supported by the pump case 47 via a needle bearing 52 and a thrust bearing 53. The input shaft 41 is spline-fitted with the turbine hub 23 of the torque converter 3, so that when the turbine runner 24 rotates, the input shaft 41 rotates integrally with the turbine runner 24.

The continuously variable transmission mechanism 42 includes a primary shaft 61, a secondary shaft 62, a primary pulley 63, a secondary pulley 64, and a belt 65.

Figure 3 is a view of the inside of the second case 12 as seen from the rear. Note that Figure 1 is a cross-sectional view of the gear change unit 1 cut along the cutting plane A-A shown in Figure 3.

The primary shaft 61 is disposed at a position where its axis is spaced downward and to the right of the axis of the input shaft 41 when viewed from the rear of the vehicle, and extends parallel to the input shaft 41. The distance between the axis of the input shaft 41 and the axis of the primary shaft 61, in other words, the distance in the axial direction (rotational radial direction) between the axis of the input shaft 41 and the axis of the primary shaft 61, is shorter than the rotational radius of the turbine runner 24 of the torque converter 3.

The secondary shaft 62 is disposed at a position where its axis is spaced apart from the axis of the input shaft 41 to the upper left when viewed from the rear of the vehicle, and extends parallel to the input shaft 41. The distance between the axis of the input shaft 41 and the axis of the secondary shaft 62, in other words, the axial distance between the axis of the input shaft 41 and the axis of the secondary shaft 62, is equal to the axial distance between the axis of the input shaft 41 and the axis of the primary shaft 61, and is shorter than the rotation radius of the turbine runner 24 of the torque converter 3.

As a result, when viewed in the longitudinal direction of the vehicle, the axial center of the primary shaft 61 and the axial center of the secondary shaft 62 are point symmetrical about the axial center of the input shaft 41. In addition, the vertical positions of the primary shaft 61 and the secondary shaft 62 are located between the uppermost and lowermost positions of the turbine runner 24 of the torque converter 3, and face the turbine runner 24 in the longitudinal direction.

As shown in FIG. 1, the primary pulley 63 includes a primary fixed sheave 71 fixed to the primary shaft 61, and a primary movable sheave 72 arranged opposite the primary fixed sheave 71 with a belt 65 sandwiched therebetween and supported on the primary shaft 61 so as to be movable in the axial direction but not rotatable relative thereto. The primary movable sheave 72 is arranged forward of the primary fixed sheave 71.

A cylinder 73 is provided on the opposite side of the primary fixed sheave 71, i.e., the front side, of the primary moving sheave 72. The inner peripheral end of the cylinder 73 is fixed to the primary shaft 61, extends radially from the primary shaft 61, and has an outer peripheral end that bends and extends rearward. The outer peripheral end of the primary moving sheave 72 abuts liquid-tightly against the outer peripheral end of the cylinder 73 from the inside in the rotational radial direction. A piston chamber (hydraulic chamber) 74 is formed between the primary moving sheave 72 and the cylinder 73.

The secondary pulley 64 is equipped with a secondary fixed sheave 75 fixed to the secondary shaft 62, and a secondary movable sheave 76 that is arranged opposite the secondary fixed sheave 75 with the belt 65 in between and is supported on the secondary shaft 62 so as to be movable in its axial direction but not rotatable relative to it. The secondary movable sheave 76 is arranged rearward of the secondary fixed sheave 75, and the positional relationship between the secondary fixed sheave 75 and the secondary movable sheave 76 in the front-to-rear direction is reversed to the positional relationship between the primary fixed sheave 71 and the primary movable sheave 72 of the primary pulley 63.

A piston 77 is provided on the opposite side of the secondary fixed sheave 75, i.e., on the rear side, of the secondary movable sheave 76. The inner peripheral end of the piston 77 is fixed to the secondary shaft 62 and extends radially from the secondary shaft 62. The outer peripheral end of the secondary movable sheave 76 extends rearward, and the outer peripheral end of the piston 77 abuts liquid-tightly against the outer peripheral end of the secondary movable sheave 76 from the inside in the rotational radial direction. A piston chamber (hydraulic chamber) 78 is formed between the secondary movable sheave 76 and the piston 77.

The secondary fixed sheave 75 and secondary movable sheave 76 of the secondary pulley 64 overlap in the vertical direction (overlap when viewed in the front-rear direction) with the primary movable sheave 72 and part of the cylinder 73. Specifically, the outer peripheral end of the primary movable sheave 72 extends in the front-rear direction with its front end bent outward in the rotational diameter direction, and the secondary fixed sheave 75 faces the portion of the outer peripheral end of the primary movable sheave 72 that extends in the front-rear direction from the outside in the rotational diameter direction, and faces the portion of the outer peripheral end that extends in the rotational diameter direction from the rear.

In the continuously variable transmission mechanism 42, the hydraulic pressure supplied to each of the piston chambers 74, 78 of the primary pulley 63 and the secondary pulley 64 is controlled to change the groove width of each of the primary pulley 63 and the secondary pulley 64, thereby continuously and steplessly changing the speed ratio (pulley ratio between the primary pulley 63 and the secondary pulley 64).

Specifically, when the gear ratio is reduced, the hydraulic pressure supplied to the piston chamber 74 of the primary pulley 63 is increased. This causes the primary movable sheave 72 of the primary pulley 63 to move toward the primary fixed sheave 71, reducing the gap (groove width) between the primary fixed sheave 71 and the primary movable sheave 72. As a result, the winding diameter of the belt 65 around the primary pulley 63 increases, and the gap (groove width) between the secondary fixed sheave 75 and secondary movable sheave 76 of the secondary pulley 64 increases. As a result, the gear ratio decreases.

When the gear ratio is increased, the hydraulic pressure supplied to the piston chamber 74 of the primary pulley 63 is reduced. This makes the thrust of the secondary pulley 64 against the belt 65 greater than the thrust of the primary pulley 63 against the belt 65, reducing the gap between the secondary fixed sheave 75 and secondary movable sheave 76 of the secondary pulley 64 and increasing the gap between the primary fixed sheave 71 and primary movable sheave 72. As a result, the gear ratio increases.

A bias spring 69 is provided in the piston chamber 68 of the secondary pulley 64. One end of the bias spring 69 elastically contacts the secondary movable sheave 76, and the other end of the bias spring 69 elastically contacts the piston 77. The elastic force of the bias spring 69 biases the secondary movable sheave 76 and the piston 77 in a direction in which they move away from each other. The secondary movable sheave 76 is applied with a biasing force by the hydraulic pressure in the piston chamber 68 and the bias spring 69, and a corresponding clamping pressure is applied to the belt 65.

The primary shaft 61 is divided into a first primary shaft 81 and a second primary shaft 82. The first primary shaft 81 is disposed in front of the second primary shaft 82. The primary pulley 63 is supported by the second primary shaft 82. A circular connection recess 83 is formed at the rear end of the first primary shaft 81. The front end of the second primary shaft 82 is inserted into the connection recess 83, and the outer peripheral surface of the second primary shaft 82 is spline-fitted with the inner peripheral surface of the connection recess 83 within the connection recess 83. The front end of the first primary shaft 81 is rotatably supported by the first case 11 via a bearing 84. The front end of the second primary shaft 82 is rotatably supported by the second case 12 via a bearing 85. An adapter 86 held by the second case 12 is disposed at the rear of the primary pulley 63, and the rear end of the second primary shaft 82 is rotatably supported by the adapter 86 via a bearing 87.

As shown in FIG. 2, an input shaft gear 91 is integrally formed on the input shaft 41 at a portion adjacent to the rear side of the portion on which the inner race of the bearing 45 is fitted. Correspondingly, a primary input gear 92 is supported on the first primary shaft 81 via a needle bearing 93 so as to be capable of relative rotation. The primary input gear 92 meshes with the input shaft gear 91 and has a larger gear diameter than the input shaft gear 91.

A forward clutch 94 is provided that utilizes the space between the meshed input shaft gear 91 and primary input gear 92 and the pump case 47 of the oil pump 46 to permit/prohibit rotation of the primary input gear 92 relative to the first primary shaft 81. A portion of the forward clutch 94 overlaps with the oil pump 46 in the radial direction of rotation (overlaps when viewed in the axial direction of rotation). The forward clutch 94 includes a clutch drum 95, a clutch hub 96, a clutch piston 97, and a canceller 98.

The clutch drum 95 has an inner peripheral end fixed to the first primary shaft 81 and extends in the direction of the rotational diameter from the first primary shaft 81, and an outer peripheral end bends and extends toward the primary input gear 92, i.e., toward the front. A number of clutch plates 101 are held on the outer peripheral end of the clutch drum 95 and arranged at intervals in the front-to-rear direction.

The clutch hub 96 is formed integrally with the primary input gear 92. The clutch hub 96 is cylindrical and extends rearward from the primary input gear 92, facing the outer circumferential end of the clutch drum 95 from the inside in the direction of the rotational diameter at a distance. The clutch hub 96 holds a number of clutch discs 102 at intervals in the front-rear direction. The clutch plates 101 and clutch discs 102 are arranged alternately in the direction of the central axis.

The clutch piston 97 is disposed between the clutch drum 95 and the clutch hub 96 so as to be movable in the axial direction of the first primary shaft 81, i.e., in the front-rear direction. The clutch piston 97 extends from the first primary shaft 81 radially outward of the first primary shaft 81, with its outer peripheral end extending and bending forward. The tip of the outer peripheral end of the clutch piston 97 abuts against the clutch plate 101. The clutch piston 97 also abuts against the clutch drum 95 in a liquid-tight manner, and a piston chamber 103 is formed between the clutch drum 95 and the clutch piston 97 to which hydraulic pressure acting on the clutch piston 97 is supplied.

The canceller 98 is provided between the clutch hub 96 and the clutch piston 97. The inner peripheral end of the canceller 98 is fixed to the first primary shaft 81. The outer peripheral end of the canceller 98 is in liquid-tight contact with the clutch piston 97. This forms a canceller chamber 104 between the clutch piston 97 and the canceller 98. A return spring 105 is provided in the canceller chamber 104, and the clutch piston 97 and the canceller 98 are elastically biased in directions away from each other by the biasing force of the return spring 105.

The clutch piston 97 moves toward the clutch plate 101 due to the hydraulic pressure supplied to the piston chamber 103, and presses the clutch plate 101. This pressure brings the clutch plate 101 and the clutch disc 102 into pressure contact, and the forward clutch 94 is engaged. The engagement of the forward clutch 94 prohibits the primary input gear 92 from rotating relative to the first primary shaft 81, and when the primary input gear 92 rotates, the first primary shaft 81 rotates together with the primary input gear 92. When the hydraulic pressure is released from the engaged state of the forward clutch 94, the clutch piston 97 is separated from the clutch plate 101 by the biasing force of the return spring 105 interposed between the clutch piston 97 and the canceller 98. As a result, the pressure contact between the clutch disc 102 and the clutch plate 101 is released, and the forward clutch 94 is released. When the forward clutch 94 is released, the primary input gear 92 is allowed to rotate relative to the first primary shaft 81, and even if the primary input gear 92 rotates, the rotation is not transmitted to the first primary shaft 81.

The secondary shaft 62 is divided into a first secondary shaft 111 and a second secondary shaft 112. The first secondary shaft 111 is disposed in front of the second secondary shaft 112. The secondary pulley 64 is supported by the second secondary shaft 112. A circular connection recess 113 is formed at the rear end of the first secondary shaft 111. The front end of the second secondary shaft 112 is inserted into the connection recess 113, and the outer peripheral surface of the second secondary shaft 112 is spline-fitted with the inner peripheral surface of the connection recess 113 within the connection recess 113. As can be seen by comparing the first secondary shaft 111 with the first primary shaft 81, the first secondary shaft 111 is the same part as the first primary shaft 81. By sharing the first primary shaft 81 and the first secondary shaft 111, the number of types of parts constituting the transmission unit 1 (vertical CVT 4) can be reduced, and the manufacturing cost of the transmission unit 1 can be reduced. The front end of the first secondary shaft 111 is rotatably supported by the first case 11 via a bearing 114. The front end of the second secondary shaft 112 is rotatably supported by the second case 12 via a bearing 115. The rear end of the second secondary shaft 112 is rotatably supported by the third case 13 via a bearing 116.

A secondary input gear 121 is supported on the second secondary shaft 112 rearward of the bearing 114 via a needle bearing 122 for relative rotation.

A reverse clutch 123 is provided that utilizes the space between the secondary input gear 121 and the pump case 47 of the oil pump 46 to permit/prohibit rotation of the secondary input gear 121 relative to the first secondary shaft 111. A portion of the reverse clutch 123 overlaps with the oil pump 46 in the radial direction of rotation (overlapping when viewed in the axial direction of rotation). The reverse clutch 123 includes a clutch drum 124, a clutch hub 125, a clutch piston 126, and a canceller 127.

The clutch drum 124 has an inner peripheral end fixed to the first secondary shaft 111, extends radially from the first secondary shaft 111, and has an outer peripheral end bent and extending toward the secondary input gear 121, i.e., toward the front. A number of clutch plates 131 are held on the outer peripheral end of the clutch drum 124 and arranged at intervals in the front-to-rear direction.

The clutch hub 125 is formed integrally with the secondary input gear 121. The clutch hub 125 is cylindrical and extends rearward from the secondary input gear 121, and faces the outer circumferential end of the clutch drum 124 from the inside in the direction of the rotational diameter with a gap therebetween. The clutch hub 125 holds a plurality of clutch discs 132 spaced apart in the front-rear direction. The clutch plates 131 and clutch discs 132 are arranged alternately in the direction of the central axis. The number of clutch plates 131 and clutch discs 132 is greater than the number of clutch plates 101 and clutch discs 102 of the forward clutch 94.

The clutch piston 126 is disposed between the clutch drum 124 and the clutch hub 125 so as to be movable in the axial direction of the first secondary shaft 111, i.e., in the front-rear direction. The clutch piston 126 extends from the first secondary shaft 111 radially outward of the first secondary shaft 111, with its outer circumferential end extending and bending forward. The tip of the outer circumferential end of the clutch piston 126 abuts against the clutch plate 131. The clutch piston 126 also abuts against the clutch drum 124 in a liquid-tight manner, and a piston chamber 133 is formed between the clutch drum 124 and the clutch piston 126 to which hydraulic pressure acting on the clutch piston 126 is supplied.

The canceller 127 is provided between the clutch hub 125 and the clutch piston 126. The inner peripheral end of the canceller 127 is fixed to the first secondary shaft 111. The outer peripheral end of the canceller 127 is in liquid-tight contact with the clutch piston 126. This forms a canceller chamber 134 between the clutch piston 126 and the canceller 127. A return spring 135 is provided in the canceller chamber 134, and the clutch piston 126 and the canceller 127 are elastically biased in directions away from each other by the biasing force of the return spring 135.

The clutch piston 126 moves toward the clutch plate 131 due to the hydraulic pressure supplied to the piston chamber 133, and presses the clutch plate 131. This pressure presses the clutch plate 131 and the clutch disc 132 together, and the reverse clutch 123 is engaged. The engagement of the reverse clutch 123 prohibits the secondary input gear 121 from rotating relative to the first secondary shaft 111, and when the secondary input gear 121 rotates, the first secondary shaft 111 rotates together with the secondary input gear 121. When the hydraulic pressure is released from the engaged state of the reverse clutch 123, the clutch piston 126 is separated from the clutch plate 131 by the biasing force of the return spring 135 interposed between the clutch piston 126 and the canceller 127. As a result, the pressure contact between the clutch disc 132 and the clutch plate 131 is released, and the reverse clutch 123 is released. When the reverse clutch 123 is released, the secondary input gear 121 is allowed to rotate relative to the first secondary shaft 111, and even if the secondary input gear 121 rotates, the rotation is not transmitted to the first secondary shaft 111.

The reverse transmission mechanism 43 is a mechanism that transmits the power (rotation) of the input shaft 41 to the secondary shaft 62 (first secondary shaft 111) without passing through the continuously variable transmission mechanism 42. The reverse transmission mechanism 43 includes a reverse shaft 141, a first reverse gear 142, and a second reverse gear 143.

The reverse shaft 141 extends in the front-rear direction parallel to the input shaft 41. The front end of the reverse shaft 141 is rotatably supported by the first case 11 via a bearing 144. The rear end of the reverse shaft 141 is rotatably supported by the second case 12 via a bearing 145. As shown in FIG. 3, the reverse shaft 141 is positioned between the uppermost and lowermost positions of the turbine runner 24 of the torque converter 3 in the up-down direction, and faces the turbine runner 24 in the front-rear direction.

The first reverse gear 142 is formed integrally with the reverse shaft 141. The first reverse gear 142 meshes with the input shaft gear 91 and has a larger gear diameter than the input shaft gear 91. The second reverse gear 143 is formed integrally with the reverse shaft 141 on the rear side of the first reverse gear 142. The second reverse gear 143 meshes with the secondary input gear 121 and has a smaller gear diameter than the secondary input gear 121.

The output shaft 44 is spaced rearward from the input shaft 41 and is arranged coaxially with the input shaft 41. In other words, the input shaft 41 and the output shaft 44 are spaced apart in the front-rear direction and are arranged to have a common axis that extends vertically along the front-rear direction of the vehicle.

The front end of the output shaft 44 is rotatably supported by the adapter 86 via a needle bearing 146. The adapter 86 overlaps the secondary movable sheave 76 and piston 77 of the secondary pulley 64 in the front-rear direction (overlapping when viewed from the radial direction of the secondary pulley 64). As a result, the output shaft 44 is positioned as close as possible to the secondary movable sheave 76 and overlaps the piston 77 in the front-rear direction. This shortens the front-rear length of the transmission unit 1 (vertical CVT 4). The output shaft 44 is rotatably supported by the third case 13 via the bearing 147, with the inner ring of the bearing 147 fitted onto a portion spaced rearward from the portion supported by the needle bearing 146.

An output shaft gear 148 is integrally formed on the output shaft 44 between the portion supported by the needle bearing 146 and the portion supported by the bearing 147. Correspondingly, a secondary output gear 149 is supported on the secondary shaft 62 (second secondary shaft 112) adjacent to the rear side of the piston 77 of the secondary pulley 64 by spline fitting so as not to rotate relative to the secondary shaft 62. The output shaft gear 148 and the secondary output gear 149 are in mesh, and the output shaft gear 148 has a larger gear diameter than the secondary output gear 149. The output shaft gear 148 overlaps with the piston 77 of the secondary pulley 64 in the vertical direction (overlaps when viewed in the front-rear direction).

<Valve body>
A valve body 151 is provided at the bottom of the second case 12. A hydraulic circuit including various valves for controlling the supply of oil to each part of the transmission unit 1 is formed in the valve body 151. An oil pan 152 is fixed to the second case 12 from below with a plurality of bolts. Oil is stored in the oil pan 152, and a strainer is immersed in the oil. When the pump gear 49 of the oil pump 46 rotates, the oil stored in the oil pan 152 is sucked up through the strainer and supplied to the valve body 151. The oil is then supplied from the valve body 151 to each part that requires a supply of oil as hydraulic oil or lubricating oil.

Hydraulic oil is supplied to the piston chamber 103 of the forward clutch 94 through an oil passage 153 that extends upward from the valve body 151 along the axial radial direction of the primary shaft 61 at a position that overlaps with the oil pump 46 in the front-to-rear direction. In the forward clutch 94, the clutch drum 95 is disposed on the oil pump 46 side relative to the clutch hub 96, and the piston chamber 103 is closer to the oil pump 46 than in a configuration in which the forward clutch 94 is reversed front-to-rear. Therefore, in the configuration of the forward clutch 94, the distance from the oil passage 153 to the piston chamber 103 can be shortened compared to a configuration in which the forward clutch 94 is reversed, and thus the oil passage length from the oil pump 46 to the piston chamber 103 can be shortened, and the shortened oil passage length can improve responsiveness.

Hydraulic oil is supplied to the piston chamber 133 of the reverse clutch 123 through an oil passage 154 that extends upward from the valve body 151 along the axial radial direction of the primary shaft 61 at a position that overlaps with the oil pump 46 in the front-rear direction. In the reverse clutch 123, the clutch drum 124 is disposed on the oil pump 46 side relative to the clutch hub 125, and the piston chamber 133 is closer to the oil pump 46 than in a configuration in which the reverse clutch 123 is reversed front-rear. Therefore, in the configuration of the reverse clutch 123, the distance from the oil passage 154 to the piston chamber 133 can be shortened compared to a configuration in which the reverse clutch 123 is reversed, and thus the oil passage length from the oil pump 46 to the piston chamber 133 can be shortened, and the shortened oil passage length can improve responsiveness.

Also, as shown in FIG. 3, a partition wall 155 is formed in the second case 12. The partition wall 155 extends along the outer periphery of the primary pulley 63 beyond the position facing the lower end of the primary pulley 63 in the vertical direction toward the secondary pulley 64 to a position facing the left end of the primary pulley 63 in the vertical direction, at which point it bends and extends to the lower left. The partition wall 155 can isolate the primary pulley 63 from the oil stored in the oil pan 152, and can prevent the lower part of the primary pulley 63 from being immersed in the oil. In addition, when the vehicle moves forward, the primary pulley 63 rotates clockwise when viewed from the rear, so that even if oil accumulates on the partition wall 155, the accumulated oil is scraped out by the primary pulley 63 to the open end side of the partition wall 155. As a result, it is possible to prevent the lower part of the primary pulley 63 from being immersed in oil, and mechanical loss caused by oil acting as resistance to the rotation of the primary pulley 63 can be reduced, thereby improving the fuel efficiency of the vehicle.

<Power transmission path>
FIG. 4 is a skeleton diagram showing the configuration of the vertically-mounted CVT 4 and a power transmission path in the vertically-mounted CVT 4. As shown in FIG.

When the vehicle moves forward, the forward clutch 94 is engaged and the reverse clutch 123 is released. The power input from the engine to the input shaft 41 via the torque converter 3 is transmitted from the input shaft gear 91 to the primary shaft 61 via the primary input gear 92 due to the engagement of the forward clutch 94. On the other hand, even if the power input to the input shaft 41 is transmitted from the input shaft gear 91 to the secondary input gear 121 and the secondary input gear 121 rotates, the secondary input gear 121 rotates freely relative to the secondary shaft 62 (first secondary shaft 111) due to the release of the reverse clutch 123, and no power is transmitted to the secondary shaft 62.

The power transmitted to the primary shaft 61 is changed in speed at a gear ratio according to the pulley ratio between the primary pulley 63 and the secondary pulley 64, and then transmitted to the secondary shaft 62. The power transmitted to the secondary shaft 62 is then transmitted from the secondary output gear 149 to the output shaft 44 via the output shaft gear 148, output from the output shaft 44 to a propeller shaft (not shown), and transmitted from the propeller shaft to the left and right rear wheels via a rear differential gear (rear diff) and a drive shaft.

Because the gear diameter of the primary input gear 92 is larger than that of the input shaft gear 91, the power of the input shaft 41 is reduced by the input shaft gear 91 and the primary input gear 92 and transmitted to the primary shaft 61. Also, because the gear diameter of the output shaft gear 148 is larger than that of the secondary output gear 149, the power of the secondary shaft 62 is reduced by the secondary shaft gear 149 and the output shaft gear 148 and transmitted to the output shaft 44. Therefore, when the vehicle is moving forward, in the power transmission path from the input shaft 41 to the output shaft 44, the input shaft gear 91 and the primary input gear 92 form a primary reduction gear mechanism 156 that reduces the power, and the output shaft gear 148 and the secondary shaft gear 149 form a secondary reduction gear mechanism 157 that further reduces the power.

For example, a configuration in which the secondary shaft 62 is directly connected to the output shaft 44 and the secondary reduction gear mechanism 157 is omitted is conceivable. In this configuration, in order to obtain a reduction ratio by the primary reduction gear mechanism 156 and the secondary reduction gear mechanism 157, the reduction ratio of the primary reduction gear mechanism 156 must be increased, and the gear diameter of the primary input gear 92 must be increased. Increasing the gear diameter of the primary input gear 92 increases the size of the vertically mounted CVT 4. Therefore, in a configuration that includes the secondary reduction gear mechanism 157 in addition to the primary reduction gear mechanism 156, the vertically mounted CVT 4 can be made smaller than in a configuration in which the secondary reduction gear mechanism 157 is omitted.

In addition, by providing the primary reduction gear mechanism 156 and the secondary reduction gear mechanism 157, when the engine specifications change, the vertically mounted CVT 4 can be adapted to the changed engine specifications by changing the design of at least one of the input shaft gear 91 and the primary input gear 92 of the primary reduction gear mechanism 156 without changing the secondary reduction gear mechanism 157.

When the vehicle is moving backwards, the forward clutch 94 is released and the reverse clutch 123 is engaged. The power input from the engine to the input shaft 41 via the torque converter 3 is transmitted from the input shaft gear 91 to the secondary shaft 62 via the reverse transmission mechanism 43 and the secondary input gear 121 due to the engagement of the reverse clutch 123. At this time, the secondary shaft 62 rotates in the opposite direction to when the vehicle is moving forward. On the other hand, even if the power input to the input shaft 41 is transmitted from the input shaft gear 91 to the primary input gear 92 and the primary input gear 92 rotates, the primary input gear 92 rotates freely relative to the primary shaft 61 (first primary shaft 81) due to the release of the forward clutch 94, and no power is transmitted to the primary shaft 61.

The power transmitted to the secondary shaft 62 is transmitted from the secondary output gear 149 via the output shaft gear 148 to the output shaft 44, output from the output shaft 44 to the propeller shaft, and transmitted from the propeller shaft to the left and right rear wheels via the rear differential gear and drive shaft.

Since the gear diameter of the first reverse gear 142 of the reverse transmission mechanism 43 is larger than the gear diameter of the input shaft gear 91, and the gear diameter of the secondary input gear 121 is larger than the gear diameter of the second reverse gear 143 of the reverse transmission mechanism 43, the power of the input shaft 41 is reduced by the input shaft gear 91, the reverse transmission mechanism 43, and the secondary input gear 121 and transmitted to the secondary shaft 62. Also, since the gear diameter of the output shaft gear 148 is larger than the gear diameter of the secondary output gear 149, the power of the secondary shaft 62 is reduced by the secondary shaft gear 149 and the output shaft gear 148 and transmitted to the output shaft 44. Therefore, when the vehicle is moving backwards, in the power transmission path from the input shaft 41 to the output shaft 44, the input shaft gear 91, the reverse transmission mechanism 43, and the secondary input gear 121 form a primary reduction gear mechanism 158 that reduces the power, and the output shaft gear 148 and the secondary shaft gear 149 form a secondary reduction gear mechanism 157 that further reduces the power.

<Action and effect>
As described above, the primary shaft 61 and the secondary shaft 62 are arranged separately on the left and right sides with respect to the input shaft 41. This makes it possible to shorten the vertical inter-shaft distance between the primary shaft 61 and the secondary shaft 62, and to reduce the vertical size of the vertically mounted CVT 4. In the transmission unit 1, the vertical size of the continuously variable transmission mechanism 42 is reduced to an extent that the vertical positions of the primary shaft 61 and the secondary shaft 62 are located between the uppermost position and the lowermost position of the torque converter 3. Therefore, even in a vehicle with a low-floor interior such as a commercial vehicle, the transmission unit 1 can be mounted on the vehicle while ensuring the minimum ground clearance of the vehicle.

The primary shaft 61 and secondary shaft 62 are offset to one side and the other side in the vertical direction relative to the input shaft 41. Specifically, in a vertically mounted CVT 4, the primary shaft 61 is positioned below the input shaft 41, and the secondary shaft 62 is positioned above the input shaft 41. This makes it possible to provide space above the primary shaft 61 in the engine compartment that houses the transmission unit 1, and to place a starter 161 for starting the engine in that space.

The vertically mounted CVT 4 is equipped with a mechanical oil pump 46 that is driven by the power of the input shaft 41. The oil pump 46 is provided on the axis of the input shaft 41 and is disposed between the primary shaft 61 and the secondary shaft 62. By arranging the oil pump 46 by making good use of the space between the primary shaft 61 and the secondary shaft 62, the size of the vertically mounted CVT 4, particularly the size in the front-rear direction, can be reduced.

In addition, in the vertically mounted CVT 4, when the vehicle moves forward, power is transmitted from the input shaft 41 to the primary shaft 61, the power is then transmitted from the primary shaft 61 to the secondary shaft 62 at a different speed, and then transmitted from the secondary shaft 62 to the output shaft 44. Therefore, when the vehicle moves forward, the power can be transmitted from the input shaft 41 to the output shaft 44 at a different speed.

On the other hand, when the vehicle is moving backwards, power is transmitted from the input shaft 41 to the secondary shaft 62, and the power is transmitted from the secondary shaft 62 to the output shaft 44. Therefore, when the vehicle is moving backwards, the power can be transmitted from the input shaft 41 to the output shaft 44 without passing through the continuously variable transmission mechanism 42. Since the power does not pass through the continuously variable transmission mechanism 42, the power transmission efficiency is improved, and the fuel efficiency of the vehicle equipped with the vertically mounted CVT 4 can be improved. Furthermore, since hydraulic pressure for controlling the shifting by the continuously variable transmission mechanism 42 is not required, the effect of improving fuel efficiency by not requiring hydraulic pressure can be obtained. In addition, when the accelerator is operated, a driving feeling with a direct feeling (linear feeling) can be obtained. Furthermore, even if an overload is input to the vehicle from the road surface, the continuously variable transmission mechanism 42 can be protected from the overload.

Furthermore, because a planetary gear mechanism is not required to switch the vehicle between forward and reverse, the longitudinally mounted CVT4 can be made more compact.

The primary movable sheave 72 of the primary pulley 63 and the secondary movable sheave 76 of the secondary pulley 64 are arranged on opposite sides of the belt 65. This allows the primary movable sheave 72 and the secondary movable sheave 76 to apply a clamping pressure to the belt 65 from both sides, thereby preventing the belt 65 from slipping.

In the secondary pulley 64, the outer peripheral end of the piston 77 contacts the outer peripheral end of the secondary movable sheave 76 from the inside in the rotational radial direction in a liquid-tight manner. Therefore, the size of the secondary movable sheave 76 in the front-rear direction is larger than the size of the primary movable sheave 72 in the front-rear direction. Therefore, in a configuration in which the primary movable sheave 72 is arranged rearward (opposite the engine side) with respect to the primary fixed sheave 71 and the secondary movable sheave 76 is arranged forward (on the engine side) with respect to the secondary fixed sheave 75, the position of the belt 65 in the axial direction shifts rearward compared to a configuration in which the primary movable sheave 72 is arranged forward with respect to the primary fixed sheave 71 and the secondary movable sheave 76 is arranged rearward with respect to the secondary fixed sheave 75, and the continuously variable transmission mechanism 42 including the primary pulley 63, secondary pulley 64, and belt 65 becomes longer in the front-rear direction accordingly.

As a result, the primary movable sheave 72 is positioned forward of the primary fixed sheave 71, and the secondary movable sheave 76 is positioned rearward of the secondary fixed sheave 75, making it possible to shorten the length of the continuously variable transmission mechanism 42 in the front-to-rear direction. By arranging other components such as the output shaft 44 in the resulting space and overlapping the other components in the axial direction of the secondary pulley 64 and the input shaft 41, it is possible to reduce the size in the axial direction while keeping the axial length short.

Furthermore, the radial size of the vertically mounted CVT 4 is reduced by overlapping a portion of the oil pump 46 with the forward clutch 94 and the reverse clutch 123 in the radial direction of the input shaft 41.

As a result, the longitudinally mounted CVT 4 can be made smaller, and even in vehicles with low-floor interiors such as commercial vehicles, it is possible to mount the transmission unit 1 including the longitudinally mounted CVT 4 on the vehicle while ensuring the vehicle's minimum ground clearance.

In addition, by reducing the size of the vertically mounted CVT 4, the weight of the transmission unit 1 can be reduced, which in turn improves the fuel efficiency of the vehicle in which the transmission unit 1 is installed. In addition, the cost can be reduced by reducing the size of the transmission unit 1.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

For example, in the above embodiment, a vertically mounted CVT4 was used as an example of a transmission, but the present invention is not limited to a vertically mounted CVT4 and can also be applied to a transmission that is mounted horizontally so that the input shaft extends in the left-right direction of the vehicle.

In addition, the power transmission system of the continuously variable transmission mechanism 42 is not limited to a belt type, but may be a chain type or a toroidal type.

In addition, various design modifications can be made to the above-mentioned configuration within the scope of the claims.

1: Transmission unit 3: Torque converter 4: Vertically mounted CVT (transmission)
41: Input shaft 42: Continuously variable transmission mechanism 44: Output shaft 61: Primary shaft 62: Secondary shaft

Claims (1)

A torque converter;
an input shaft to which power from a drive source is input via the torque converter;
an output shaft arranged coaxially with the input shaft and spaced apart from the input shaft in an axial direction of the input shaft;
a continuously variable transmission mechanism that is provided on a power transmission path between the input shaft and the output shaft, has a primary shaft and a secondary shaft each extending parallel to the input shaft, and transmits power from the primary shaft to the secondary shaft at a variable speed;
a reverse shaft extending parallel to the input shaft, receiving power from the input shaft and transmitting the power to the secondary shaft;
the primary shaft, the secondary shaft and the reverse shaft are positioned between the uppermost position and the lowermost position of the torque converter in the vertical direction;
the reverse shaft is disposed above the primary shaft and the secondary shaft, is located between the primary shaft and the secondary shaft when viewed from a top-bottom direction, and overlaps with the primary shaft and the secondary shaft when viewed from a direction perpendicular to the axial direction.

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