JP7471744B2 - Oil supply structure - Google Patents

Description

The present invention relates to a structure for supplying oil to a rotating shaft.

For example, in a vehicle equipped with a transmission, engine power is input to the transmission via a torque converter, and the power changed in speed by the transmission is transmitted to the drive wheels via a differential gear or the like. Widely known types of transmission include the continuously variable transmission (CVT) and the stepped automatic transmission (AT).

In a belt-type continuously variable transmission, an input shaft, to which power from the engine is input, is connected to a primary shaft of a continuously variable transmission mechanism so that the power can be transmitted, and the power input to the input shaft is transmitted from the input shaft to the primary shaft. In a continuously variable transmission mechanism, a secondary shaft is arranged parallel to the primary shaft at a distance from the primary shaft, 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. The power transmitted to the secondary pulley is then transmitted to the output shaft via the secondary shaft, and the power is transmitted from the output shaft to the left and right drive wheels via a differential gear.

JP 2012-192855 A

To shorten the overall length of a belt-type continuously variable transmission, a reverse idler shaft (reverse idler gear) that reverses the power input from the input shaft to the primary shaft when the vehicle is moving backward compared to when moving forward can be provided above the input shaft, eliminating the planetary gear mechanism for switching between forward and reverse travel between the input shaft and the primary shaft. However, with this configuration, the reverse idler shaft is located above the input shaft, which increases the vertical size of the continuously variable transmission.

The reverse idler shaft is rotatably supported by a case that forms the outer shell of the continuously variable transmission via bearings such as ball bearings. Since friction occurs between parts in the bearings (for example, friction between the races and the rolling elements), it is essential to supply oil for lubrication to the bearings. For this reason, it is also necessary to supply oil for lubrication to the bearings of the reverse idler shaft, which is located above the input shaft. In order to prevent the continuously variable transmission from becoming even larger in the vertical direction, considerable ingenuity is required in the structure that supplies oil to the bearings of the reverse idler shaft.

The object of the present invention is to provide an oil supply structure that can supply oil to the bearings of rotating bodies such as reverse idler shafts while preventing the vertical size of the transmission from increasing.

To achieve the above object, the oil supply structure of the present invention is a structure for supplying oil to bearings in a transmission in which a rotor is provided inside a unit case and the rotor is rotatably supported by the unit case via bearings, and the unit case is formed with a breather chamber that communicates with the outside of the unit case via a breather on one side of the rotor in the direction of the rotor's rotation axis, the breather chamber is open on the rotor side, and the bearing is fitted and held in the opening of the breather chamber.

According to this configuration, within the unit case, the rotor is rotatably supported by the unit case via a bearing. A breather chamber is formed in the unit case. The breather chamber communicates with the outside of the unit case via the breather. Therefore, when pressure inside the unit case increases, the pressure can be released to the atmosphere via the breather.

The breather chamber opens towards the rotor, and the rotor's bearing is fitted and held in the opening of the breather chamber. This allows the oil stored in the breather chamber to be supplied to the bearing, allowing the bearing to be well lubricated with the oil. Moreover, since the breather chamber is formed on one side of the rotor in the direction of the rotation axis, there is no risk of the transmission becoming larger in the vertical direction due to the configuration in which the bearing is held in the opening of the breather chamber.

This makes it possible to supply oil to the bearings of rotating bodies such as the reverse idler shaft while preventing the vertical size of the transmission from increasing.

The bearing includes a first bearing and a second bearing that are arranged on one side and the other opposite side of the rotation axis direction, respectively, and the first bearing is fitted and held in the opening of the breather chamber, and the unit case is formed with an opposing wall portion that faces the second bearing from the other side in the rotation axis direction with a gap therebetween, and a bearing holder that protrudes from the opposing wall portion and holds the second bearing, and the rotor may be formed with a central hole that penetrates between the end face on one side in the rotation axis direction and the end face on the other side along the rotation axis.

In this configuration, the first bearing of the rotor is fitted and held in the opening of the breather chamber. The unit case is formed with an opposing wall portion that faces the second bearing of the rotor from the other side in the rotational axis direction, and a bearing holder that protrudes from the opposing wall portion to one side in the rotational axis direction. The second bearing of the rotor is held in the bearing holder, and a gap is generated between the second bearing and the opposing wall portion. Therefore, oil accumulated in the breather chamber can be supplied to the first bearing, and the oil can also be supplied to the second bearing through a center hole formed in the rotor and the gap between the second bearing and the opposing wall portion. As a result, both the first bearing and the second bearing can be well lubricated with oil.

The rotor may be formed with a central hole that extends along the rotation axis and is open at least on one end surface in the direction of the rotation axis, and radial holes that are connected to the central hole, extend in a direction intersecting the rotation axis, and are open on the circumferential surface of the rotor.

In this configuration, the rotor is formed with a central hole extending along the rotation axis, and radial holes connected to the central hole and extending in a direction intersecting the rotation axis. The central hole is open at least on one end face of the rotor in the rotation axis direction, i.e., the end face on the breather chamber side. The radial holes are open on the circumferential surface of the rotor. Therefore, oil accumulated in the breather chamber can be supplied to the bearing, and the oil can be supplied to the periphery of the rotor via the central hole and radial holes formed in the rotor. As a result, the bearing and the members arranged around the rotor can be well lubricated with oil.

According to the present invention, it is possible to supply oil to the bearings of rotating bodies such as the reverse idler shaft while preventing the vertical size of the transmission from increasing.

1 is a cross-sectional view showing a configuration of a speed change unit according to one embodiment of the present invention. FIG. 2 is a skeleton diagram illustrating the configuration of a CVT. 2 is a cross-sectional view showing the vicinity of a reverse transmission mechanism in an enlarged scale compared to FIG. 1 .

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 an embodiment of the present invention. 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 2 (E/G) 2, which serves as a driving source for traveling. The vehicle has a front engine, rear drive (FR) layout.

Engine 2 is, for example, a three-cylinder, four-stroke engine, and is mounted vertically with the crankshaft oriented vertically relative to the front-to-rear direction of the vehicle body. The number of cylinders in engine 2 is not limited to three, but may be four or more, or two or less. In addition, the number of strokes in engine 2 is not limited to four, but may be two.

The transmission unit 1 includes a torque converter 4 and a CVT (Continuously Variable Transmission) 5 housed within a unit case 3 that forms the outer shell.

<Unit case>
The unit case 3 is divided into three parts: a first transmission case 11, a second transmission case 12, and a third transmission case 13. The first transmission case 11, the second transmission case 12, and the third transmission case 13 are made of, for example, an aluminum alloy, and are cast by die casting.

The first transmission case 11, the second transmission case 12, and the third transmission case 13 are arranged in this order from the front side (engine 2 side). The first transmission case 11 and the second transmission case 12 are fastened together with bolts, and the second transmission case 12 and the third transmission case 13 are fastened together with bolts 17, so that the first transmission case 11, the second transmission case 12, and the third transmission case 13 are integrated together.

<Torque converter>
The torque converter 4 is housed in the first transmission case 11. The torque converter 4 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 fore-and-aft direction of the vehicle (body), with its outer circumferential end bent toward the rear, which is the opposite side to the engine 2 (the side toward the continuously variable transmission 42, described below). The center of the front cover 21 bulges forward. The crankshaft of the engine 2 is connected to this bulging portion so that it cannot rotate relative to the engine 2.

The pump impeller 22 is disposed behind 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 2 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 4 acts as an amplifier, and a torque greater than the engine torque is generated in the turbine runner 24.

<CVT>
The CVT 5 is housed in the second transmission case 12 and the third transmission case 13. The CVT 5 includes an input shaft 41, a continuously variable transmission mechanism 42, an output shaft 43, and a reverse transmission mechanism 44. The transmission unit 1 is disposed behind the engine 2 in a vertical orientation such that the input shaft 41 of the CVT 5 is oriented vertically and extends in the front-to-rear direction of the vehicle, and is inclined downward toward the rear.

The input shaft 41 is formed as a hollow shaft and extends along the rotation axis of the torque converter 4. The front end of the input shaft 41 is inserted into the torque converter 4 and is spline-fitted with the turbine hub 23.

In the following description, the direction in which the axis (shaft center) of the input shaft 41 extends is referred to as the "axial direction." The direction perpendicular to the axial direction, i.e., the radial direction of the input shaft 41, is referred to as the "axial radial direction."

The rear end of the input shaft 41 is rotatably supported by a mechanical oil pump 45 arranged in the second transmission case 12. Specifically, the oil pump 45 includes a pump case 46, a pump cover 47 joined to the pump case 46 from the rear, a pump gear 48 arranged in the space inside the pump case 46, and a pump shaft 49 connected to the pump gear 48 so as not to rotate relative to the pump case 46. The pump cover 47 is fixed to the second transmission case 12 and closes the space inside the pump case 46 from the rear. At the front end of the pump case 46, a bearing recess 51 is formed that is open to the front side and recessed into a substantially cylindrical shape on the rear side. The rear end of the input shaft 41 is inserted into the bearing recess 51 and rotatably supported by the pump case 46 via a ball bearing 52 interposed between the circumferential surface of the input shaft 41 and the inner circumferential surface of the bearing recess 51. In other words, a ball bearing 52 is fitted onto the rear end of the input shaft 41, and the ball bearing 52 is fitted into the bearing recess 51, so that the rear end of the input shaft 41 is rotatably supported by the pump case 46 via the ball bearing 52.

The pump shaft 49 is disposed to penetrate the pump case 46 and the pump cover 47. The pump shaft 49 extends forward from the pump case 46 and is inserted into the input shaft 41 with a gap between it and its inner circumferential surface. The front end of the pump shaft 49 reaches the front cover 21 of the torque converter 4 and is connected to the center of the front cover 21 so as not to rotate relative to it. As a result, when the front cover 21 rotates due to the power of the engine 2, the pump shaft 49 and the pump gear 48 rotate integrally with the front cover 21, and oil pressure is generated from the oil pump 45.

The continuously variable transmission mechanism 42 includes a primary shaft 54, a secondary shaft 55, a primary pulley 56, a secondary pulley 57, and a belt 58.

The primary shaft 54 and secondary shaft 55 extend parallel to the input shaft 41 between the first transmission case 11 and the second transmission case 12 and are rotatable about their respective axes.

The primary pulley 56 includes a primary fixed sheave 61 fixed to the primary shaft 54, and a primary movable sheave 62 arranged opposite the primary fixed sheave 61 with a belt 58 sandwiched therebetween, and supported on the primary shaft 54 so as to be movable in the axial direction but unable to rotate relative to the primary shaft 54. The primary movable sheave 62 is arranged forward of the primary fixed sheave 61. A cylinder 63 is provided on the opposite side of the primary movable sheave 62 from the primary fixed sheave 61, i.e., on the forward side, and a hydraulic chamber (piston chamber) 64 is formed between the primary movable sheave 62 and the cylinder 63.

The secondary pulley 57 includes a secondary fixed sheave 65 fixed to the secondary shaft 55, and a secondary movable sheave 66 arranged opposite the secondary fixed sheave 65 with the belt 58 in between, and supported on the secondary shaft 55 so as to be movable in the axial direction but not rotatable relative to the secondary shaft 55. The secondary movable sheave 66 is arranged on the rear side of the secondary fixed sheave 65. A piston 67 is provided on the opposite side of the secondary movable sheave 66 from the secondary fixed sheave 65, i.e., on the rear side, and a hydraulic chamber 68 is formed between the secondary movable sheave 66 and the piston 67.

The belt 58 is endless and is wound around the primary pulley 56 while being sandwiched between the primary fixed sheave 61 and the primary movable sheave 62, and is wound around the secondary pulley 57 while being sandwiched between the secondary fixed sheave 65 and the secondary movable sheave 66.

In the continuously variable transmission mechanism 42, the oil pressure supplied to each of the hydraulic chambers 64, 68 of the primary pulley 56 and the secondary pulley 57 is controlled to change the groove width of each of the primary pulley 56 and the secondary pulley 57, thereby continuously and steplessly changing the belt transmission ratio (pulley ratio between the primary pulley 56 and the secondary pulley 57) within a certain transmission ratio range.

Specifically, when the belt speed ratio is reduced, the hydraulic pressure supplied to the hydraulic chamber 64 of the primary pulley 56 is increased. This causes the primary movable sheave 62 of the primary pulley 56 to move toward the primary fixed sheave 61, reducing the gap (groove width) between the primary fixed sheave 61 and the primary movable sheave 62. As a result, the winding diameter of the belt 58 around the primary pulley 56 increases, and the gap (groove width) between the secondary fixed sheave 65 and secondary movable sheave 66 of the secondary pulley 57 increases. As a result, the belt speed ratio decreases.

When the belt transmission ratio is increased, the hydraulic pressure supplied to the hydraulic chamber 64 of the primary pulley 56 is reduced. This makes the thrust of the secondary pulley 57 against the belt 58 greater than the thrust of the primary pulley 56 against the belt 58, reducing the gap between the secondary fixed sheave 65 and secondary movable sheave 66 of the secondary pulley 57 and increasing the gap between the primary fixed sheave 61 and primary movable sheave 62. As a result, the belt transmission ratio increases.

A bias spring 69 is provided in the hydraulic chamber 68 of the secondary pulley 57. One end of the bias spring 69 elastically contacts the secondary movable sheave 66, and the other end of the bias spring 69 elastically contacts the piston 67. The elastic force of the bias spring 69 biases the secondary movable sheave 66 and the piston 67 in directions that move them away from each other. The hydraulic pressure in the hydraulic chamber 68 and the biasing force of the bias spring 69 are applied to the secondary movable sheave 66, and a corresponding clamping pressure is applied to the belt 58.

An input gear 81 is formed integrally with the input shaft 41 at the center in the axial direction. Correspondingly, a primary input gear 82 meshing with the input gear 81 is supported on the primary shaft 54 so as to be capable of relative rotation. A forward clutch 83 is provided that allows/prohibits rotation of the primary input gear 82 relative to the primary shaft 54, utilizing the space between the oil pump 45 and the input gears 81 and 82 that mesh with each other. A portion of the forward clutch 83 overlaps with the oil pump 45 in the axial direction (overlaps when viewed in the axial direction).

The forward clutch 83 includes a clutch drum 84, a clutch hub 85, and a clutch piston 86. The inner peripheral end of the clutch drum 84 is fixed to the primary shaft 54, extends from the primary shaft 54 in the axial direction, and the outer peripheral end is bent and extends toward the primary input gear 82, i.e., the front side. The clutch hub 85 is formed integrally with the primary input gear 82, has a cylindrical shape extending rearward from the primary input gear 82, and faces the outer peripheral end of the clutch drum 84 from the inside in the axial direction with a gap therebetween. The clutch piston 86 is provided between the clutch drum 84 and the clutch hub 85 so as to be movable in the axial direction. The clutch piston 86 is in liquid-tight contact with the clutch drum 84, and a hydraulic chamber 87 is formed between the clutch drum 84 and the clutch piston 86 to which hydraulic pressure acting on the clutch piston 86 is supplied. The clutch piston 86 is elastically biased rearward by a return spring 88.

In the space between the outer circumferential end of the clutch drum 84 and the clutch hub 85 in the axial direction, the clutch plates held by the clutch drum 84 and the clutch discs held by the clutch hub 85 are arranged alternately in the axial direction. When the clutch piston 86 moves forward and presses the clutch plates from the rear due to the hydraulic pressure supplied to the hydraulic chamber 87, the clutch plates and the clutch discs are pressed together, and the forward clutch 83 is engaged. When the forward clutch 83 is engaged, the primary input gear 82 is prohibited from rotating relative to the primary shaft 54, and when the primary input gear 82 rotates, the primary shaft 54 rotates together with the primary input gear 82. When the hydraulic pressure is released from the engaged state of the forward clutch 83, the clutch piston 86 moves rearward due to the biasing force of the return spring 88, the pressure contact between the clutch discs and the clutch plates is released, and the forward clutch 83 is released. By releasing the forward clutch 83, the primary input gear 82 is allowed to rotate relative to the primary shaft 54, and even if the primary input gear 82 rotates, the rotation is not transmitted to the primary shaft 54.

A secondary input gear 91 is supported on the secondary shaft 55 so as to be capable of relative rotation. The secondary input gear 91 is disposed between the input gear 81 and the oil pump 45 in the axial direction. In addition, a reverse clutch 92 is provided that utilizes the space between the secondary input gear 91 and the oil pump 45 to permit/prohibit rotation of the secondary input gear 91 relative to the secondary shaft 55. A portion of the reverse clutch 92 overlaps with the oil pump 45 in the axial direction (overlaps when viewed in the axial direction).

The reverse clutch 92 includes a clutch drum 93, a clutch hub 94, and a clutch piston 95. The inner peripheral end of the clutch drum 93 is fixed to the secondary shaft 55, extends from the secondary shaft 55 in the axial direction, and the outer peripheral end is bent and extends toward the secondary input gear 91, i.e., the front side. The clutch hub 94 is formed integrally with the secondary input gear 91, has a cylindrical shape extending rearward from the secondary input gear 91, and faces the outer peripheral end of the clutch drum 93 from the inside in the axial direction with a gap therebetween. The clutch piston 95 is provided between the clutch drum 93 and the clutch hub 94 so as to be movable in the axial direction. The clutch piston 95 is in liquid-tight contact with the clutch drum 93, and a hydraulic chamber 96 is formed between the clutch drum 93 and the clutch piston 95 to which hydraulic pressure acting on the clutch piston 95 is supplied. The clutch piston 95 is elastically biased rearward by a return spring 97.

In the space between the outer circumferential end of the clutch drum 93 and the clutch hub 94 in the axial direction, the clutch plates held by the clutch drum 93 and the clutch discs held by the clutch hub 94 are arranged alternately in the axial direction. When the clutch piston 95 moves forward and presses the clutch plates from the rear due to the hydraulic pressure supplied to the hydraulic chamber 96, the clutch plates and the clutch discs are pressed together, and the reverse clutch 92 is engaged. When the reverse clutch 92 is engaged, the secondary input gear 91 is prohibited from rotating relative to the secondary shaft 55, and when the secondary input gear 91 rotates, the secondary shaft 55 rotates together with the secondary input gear 91. When the hydraulic pressure is released from the engaged state of the reverse clutch 92, the clutch piston 95 moves rearward due to the biasing force of the return spring 97, the pressure contact between the clutch discs and the clutch plates is released, and the reverse clutch 92 is released. When the reverse clutch 92 is released, the secondary input gear 91 is allowed to rotate relative to the secondary shaft 55, and even if the secondary input gear 91 rotates, the rotation is not transmitted to the secondary shaft 55.

The output shaft 43 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 43 are arranged to have a common axis that extends vertically along the front-rear direction of the vehicle, with a space between them in the axial direction. An output transmission gear 101 is integrally formed with the output shaft 43. Correspondingly, a secondary output gear 102 that meshes with the output transmission gear 101 is supported on the secondary shaft 55 so as not to rotate relative to the input shaft 41.

The reverse transmission mechanism 44 is a mechanism that transmits the power (rotation) of the input shaft 41 to the secondary input gear 91. The reverse transmission mechanism 44 includes a reverse idler shaft 103, a first reverse gear 104, and a second reverse gear 105. The reverse idler shaft 103 extends in the axial direction, straddles the first transmission case 11 and the second transmission case 12, and is rotatably supported by the first transmission case 11 and the second transmission case 12. The first reverse gear 104 is formed integrally with the reverse idler shaft 103 and meshes with the input gear 81. The second reverse gear 105 is formed integrally with the reverse idler shaft 103 on the rear side of the first reverse gear 104, and meshes with the secondary input gear 91.

An adapter 111 is provided between the output shaft 43 and the primary shaft 54. The adapter 111 is made of, for example, an aluminum alloy, and is a casting cast by a die casting method. The adapter 111 extends in the axial direction between the output shaft 43 and the primary shaft 54. The upper end of the adapter 111 protrudes to the rear side, and a recess 112 that is recessed in a substantially cylindrical shape on the front side is formed in the protruding portion. The front end of the output shaft 43 is inserted into the recess 112. A radial bearing 113 is interposed between the circumferential surface of the output shaft 43 and the inner circumferential surface of the recess 112. The front end of the output shaft 43 is rotatably supported by the adapter 111 via the radial bearing 113. In addition, an annular stepped surface along the axial direction is formed in the output shaft 43 between the portion where the output transmission gear 101 is formed and the portion inserted into the recess 112. A thrust bearing 114 is interposed between the stepped surface and the adapter 111. As a result, the front end of the output shaft 43 is rotatably supported by the adapter 111 via a radial bearing 113 and a thrust bearing 114.

The adapter 111 also has a recess 115 formed on the rear side, which is recessed into a generally cylindrical shape. The rear end of the primary shaft 54 is inserted into the recess 115. A ball bearing 116 is interposed between the circumferential surface of the primary shaft 54 and the inner circumferential surface of the recess 115. The rear end of the primary shaft 54 is rotatably supported by the adapter 111 via the ball bearing 116.

A bolt 117 is inserted from the front into the lower end of the adapter 111. The adapter 111 is attached to the third transmission case 13 by the bolt 117.

<Power transmission path>
FIG. 2 is a skeleton diagram illustrating the configuration of the CVT 5. As shown in FIG.

When the vehicle moves forward, the forward clutch 83 is engaged and the reverse clutch 92 is released. The power input from the engine 2 to the input shaft 41 via the torque converter 4 is transmitted from the input gear 81 to the primary shaft 54 via the primary input gear 82 due to the engagement of the forward clutch 83. On the other hand, even if the power input to the input shaft 41 is transmitted from the input gear 81 to the secondary input gear 91 and the secondary input gear 91 rotates, the secondary input gear 91 rotates freely relative to the secondary shaft 55 (secondary shaft 55) due to the release of the reverse clutch 92, and no power is transmitted to the secondary shaft 55.

The power transmitted to the primary shaft 54 is changed in speed at a belt gear ratio according to the pulley ratio between the primary pulley 56 and the secondary pulley 57, and then transmitted to the secondary shaft 55. The power transmitted to the secondary shaft 55 is then transmitted from the secondary output gear 102 to the output shaft 43 via the output transmission gear 101.

When the vehicle is moving backwards, the forward clutch 83 is released and the reverse clutch 92 is engaged. The power input from the engine 2 to the input shaft 41 via the torque converter 4 is transmitted from the input gear 81 to the secondary shaft 55 via the reverse transmission mechanism 44 and the secondary input gear 91 by the engagement of the reverse clutch 92. At this time, the secondary shaft 55 rotates in the opposite direction to when the vehicle is moving forwards. On the other hand, even if the power input to the input shaft 41 is transmitted from the input gear 81 to the primary input gear 82 and the primary input gear 82 rotates, the primary input gear 82 rotates freely relative to the primary shaft 54 (primary shaft 54) due to the release of the forward clutch 83, and no power is transmitted to the primary shaft 54.

The power transmitted to the secondary shaft 55 is transmitted from the secondary output gear 102 to the output shaft 43 via the output transmission gear 101.

The power transmitted to the output shaft 43 is then output from the output shaft 43 to the propeller shaft 118, and transmitted from the propeller shaft 118 to the left and right rear wheels via the rear differential gear (rear diff) and the drive shafts.

<Oil supply structure>
As shown in FIG. 1 , a valve body 121 for controlling the supply of oil to each part of the speed change unit 1 is provided at the bottom of the second transmission case 12 .

A strainer 122 is provided at the bottom of the second transmission case 12. The strainer 122 includes a filtering section 123 arranged side by side with the valve body 121, and a pipe section 124 extending from the filtering section 123. The pipe section 124 extends forward from the lower part of the filtering section 123 and below the valve body 121. The pipe section 124 is formed in a hollow tubular shape, and its interior is connected to the interior of the filtering section 123. The underside of the tip of the pipe section 124 opens as a suction port 125 for sucking in oil.

An oil pan 131 is fixed from below to the second transmission case 12 with multiple bolts 132. The tip of the tube section 124 of the strainer 122 is located in the center of the oil pan 131, and the suction port 125 at the tip faces the center of the oil pan 131.

The rotation of the pump gear 48 of the oil pump 45 generates a suction force, which draws the oil stored in the oil pan 131 into the pipe section 124 through the suction port 125. The oil drawn into the pipe section 124 flows through the pipe section 124 toward the filter section 123 and passes through the filter material provided in the filter section 123. As the oil passes through the filter material, foreign matter contained in the oil is captured by the filter material and removed from the oil. The oil that has passed through the filter material is supplied to the valve body 121 via the oil pump 45. The oil is then supplied from the valve body 121 to each part that requires a supply of oil, such as the continuously variable transmission 42, as hydraulic oil or lubricating oil.

Figure 3 is a cross-sectional view showing the reverse transmission mechanism 44 and its vicinity at a larger scale than Figure 1.

A breather chamber 141 is formed in the second transmission case 12 behind the reverse idler shaft 103. The breather chamber 141 opens forward in a circular shape and is recessed rearward from the opening 142. A breather 143 is provided at the top of the breather chamber 141 to release the pressure inside the unit case 3 to the atmosphere. The breather 143 connects the breather chamber 141 to the outside of the unit case 3.

In addition, the first transmission case 11 is formed with a flat plate-shaped opposing wall portion 144 at a portion facing the reverse idler shaft 103 from the front in the axial direction, and a ring-shaped bearing holder portion 145 protruding from the opposing wall portion 144 to the rear.

The outer rings of a first ball bearing 146 and a second ball bearing 147 are fitted and fixed to the opening 142 of the breather chamber 141 and the bearing holder 145 of the first transmission case 11, respectively. The rear end and the front end of the reverse idler shaft 103 are inserted into the inner rings of the first ball bearing 146 and the second ball bearing 147, respectively. As a result, the reverse idler shaft 103 is rotatably supported by the second transmission case 12 via the first ball bearing 146, and is rotatably supported by the first transmission case 11 via the second ball bearing 147. A gap 148 is formed between the second ball bearing 147 and the opposing wall 144.

The reverse idler shaft 103 is formed with a central hole 151 and a radial hole 152. The central hole 151 extends along the rotation axis of the reverse idler shaft 103 and penetrates between the front end face and the rear end face of the reverse idler shaft 103. The radial hole 152 has one end connected to the central hole 151, extends in the axial direction between the first reverse gear 104 and the second reverse gear 105, and has the other end open on the circumferential surface of the reverse idler shaft 103.

<Action and effect>
As described above, within the unit case 3, the reverse idler shaft 103 is rotatably supported by the unit case 3 via the first ball bearing 146 and the second ball bearing 147. A breather chamber 141 is formed in the unit case 3. The breather chamber 141 communicates with the outside of the unit case 3 via the breather 143. When pressure inside the unit case 3 increases, the pressure can be released to the atmosphere via the breather 143.

The breather chamber 141 opens toward the reverse idler shaft 103, and a first ball bearing 146 is fitted and held in an opening 142 of the breather chamber 141. The unit case 3 is formed with an opposing wall portion 144 that faces the second ball bearing 147 from the front in the axial direction, and a bearing holder portion 145 that protrudes from the opposing wall portion 144 to the rear in the axial direction. The second ball bearing 147 is held in the bearing holder portion 145, and a gap 148 is formed between the second ball bearing 147 and the opposing wall portion 144.

The reverse idler shaft 103 is formed with a central hole 151. The central hole 151 extends along the rotation axis of the reverse idler shaft 103 and penetrates between the front end face and the rear end face of the reverse idler shaft 103.

Therefore, the oil stored in the breather chamber 141 can be supplied to the first ball bearing 146, and the oil can be supplied to the second ball bearing 147 through the center hole 151 formed in the reverse idler shaft 103 and the gap 148 between the second ball bearing 147 and the opposing wall portion 144. As a result, both the first ball bearing 146 and the second ball bearing 147 can be well lubricated with oil.

In addition, since the breather chamber 141 is formed rearward relative to the reverse idler shaft 103, the first ball bearing 146 is held in the opening 142 of the breather chamber 141, so there is no risk of the transmission unit 1 becoming larger in the vertical direction.

This allows oil to be supplied to the first ball bearing 146 and the second ball bearing 147 while preventing the vertical size of the gear change unit 1 from increasing.

The reverse idler shaft 103 is also formed with a radial hole 152 that is connected to the central hole 151 and extends in a direction intersecting the rotation axis. The radial hole 152 is open on the circumferential surface of the reverse idler shaft 103. Therefore, the oil that has accumulated in the breather chamber 141 can be supplied to the periphery of the reverse idler shaft 103 via the central hole 151 and radial hole 152 of the reverse idler shaft 103. As a result, the members arranged around the reverse idler shaft 103 can be well lubricated with oil.

<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, the transmission unit 1 is disposed vertically behind the engine 2, with the input shaft 41 of the CVT 5 extending vertically in the front-to-rear direction of the vehicle. However, this is not limited to this, and the present invention can also be applied to a transmission unit that is disposed horizontally on the left or right side of the engine 2, with the input shaft of the CVT extending in the left-to-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.

Furthermore, the transmission mechanism provided in the transmission unit 1 is not limited to the continuously variable transmission mechanism 42, but may be a stepped transmission mechanism.

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

1: Gear unit (transmission)
3: Unit case 12: Second transmission case (unit case)
13: Third transmission case (unit case)
103: Reverse idler shaft (rotating body)
141: Breather chamber 142: Opening portion 143: Breather 144: Opposing wall portion 145: Bearing holder portion 146: First ball bearing (first bearing)
147: Second ball bearing (second bearing)
148: Gap (spacing)
151: central hole 152: radial hole

Claims (3)

A transmission in which a rotating body is provided in a unit case, and the rotating body is rotatably supported by the unit case via a bearing, the transmission having a structure for supplying oil to the bearing,
A breather chamber is formed in the unit case on one side of the rotor in the direction of the rotation axis of the rotor , and a hole is formed in the breather chamber penetrating in the vertical direction between a top surface and an outer surface of the breather chamber,
the breather chamber communicates with the outside of the unit case via a breather inserted into the hole and opens to the rotating body side,
The bearing is fitted and held in an opening portion of the breather chamber ,
An oil supply structure in which the bearing is arranged so that the lower end of the breather and a portion of the bottom surface of the breather chamber that faces the breather in the vertical direction are located at a height position between its inner surface and outer surface . the bearings include a first bearing and a second bearing respectively disposed on the one side and the opposite other side in the rotation axis direction,
The first bearing is fitted and held in the opening of the breather chamber,
the unit case is formed with an opposing wall portion that faces the second bearing from the other side in the rotational axis direction at a distance, and a bearing holding portion that protrudes from the opposing wall portion and holds the second bearing,
2. The oil supply structure according to claim 1, wherein the rotor has a center hole formed along the rotation axis, the center hole penetrating between the end face on the one side and the end face on the other side in the direction of the rotation axis. The oil supply structure according to claim 1 or 2, wherein the rotor is formed with a central hole that extends along the rotation axis and is open at least at one end face in the direction of the rotation axis, and radial holes that are connected to the central hole, extend in a direction intersecting the rotation axis, and are open at the peripheral surface of the rotor.

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