Belt type continuously variable transmission for vehicle

A belt type continuously variable transmission for a vehicle includes: an input shaft and an output shaft disposed in parallel with each other; a pair of groove width variable pulleys disposed on the outer circumferential sides of the input shaft and the output shaft; and a transmission belt wound around each of V-grooves of the pair of the groove width variable pulleys, the belt type continuously variable transmission for a vehicle changing a winding diameter of the transmission belt by changing the groove widths of the V-grooves so as to continuously vary a gear ratio, wherein the groove width variable pulley includes a fixed sheave fixed to an outer circumferential surface of one of the input shaft and the output shaft, and a movable sheave disposed relatively non-rotatably on the one shaft and relatively movably in the direction of the shaft center of the one shaft so as to form the V-groove with the fixed sheave, wherein the belt type continuously variable transmission for a vehicle is disposed with a parking gear having a disc-shaped main body portion fixed to the one shaft on the side opposite to the movable sheave relative to the fixed sheave, and an annular projecting portion projecting from the main body portion toward a wall surface of the fixed sheave on the side opposite to the movable sheave and abutting on the wall surface of the opposite side on the outer circumferential side than the minimum winding diameter of the transmission belt, and wherein the annular projecting portion of the parking gear abuts on the wall surface of the fixed sheave on the side opposite to the movable sheave at a radial position corresponding to the maximum winding diameter of the transmission belt.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of International Application No. PCT/JP2010/058843, filed May 25, 2010, and claims the priority of International Application No. PCT/JP2010/053576, filed Mar. 4, 2010, the content of both of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a belt type continuously variable transmission for a vehicle and particularly to a technique of suppressing the fall of a fixed sheave.

BACKGROUND ART

A belt type continuously variable transmission for a vehicle is known that includes an input shaft and an output shaft disposed in parallel with each other, a pair of groove width variable pulleys disposed on the outer circumferential sides of the input shaft and the output shaft, and a transmission belt wound around each of V-grooves of the pair of the groove width variable pulleys and that changes a winding diameter of the transmission belt by changing the groove widths of the V-grooves so as to continuously vary a gear ratio. For example, this corresponds to those described in Patent Documents 1 to 9.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

A groove width variable pulley of Patent Documents 1 to 3 and 8 includes a fixed sheave fixed to a rotation shaft and a movable sheave disposed on the rotation shaft movably in a shaft center direction and relatively non-rotatably around the shaft center to form a V-groove with the fixed sheave, and the transmission belt is clamped between the fixed sheave and the movable sheave. In this case, the fixed sheave is affected by the moment causing the fixed sheave to fall toward the side opposite to the transmission belt with a base portion, i.e., an inner circumferential portion of the fixed sheave used as a fulcrum due to a force in the shaft center direction out of a reaction force applied from the transmission belt. Therefore, a conventional belt type continuously variable transmission has a problem of lowering of transmission torque due to reduction in a contact area between the fixed sheave and the transmission belt because the fixed sheave is deformed in the direction of falling toward the side opposite to the movable sheave. Although the problem is addressed by, for example, increasing the thickness of the fixed sheave in the shaft center direction to improve the strength, this is disadvantageous because of increase in the manufacturing cost and weight of the continuously variable transmission.

In this regard, for example, Patent Document 4 describes an elastic member, for example, a plate spring biasing the fixed sheave toward the movable sheave from the side opposite to the movable sheave so as to resist the reaction force. Patent Document 9 describes a fixed sheave having a clamping pulley portion disposed on a rotation shaft such that a V-groove is formed with a movable sheave, and a support pulley portion disposed on the side opposite to the movable sheave relative to the clamping pulley portion and supporting the clamping pulley portion so as to resist a reaction force applied to the clamping pulley portion from the transmission belt. However, these are disadvantageous since the elastic member and a bearing supporting the member must newly be added or the fixed sheave must be formed in a divided manner, increasing the number of parts. Patent Documents 5 to 7 describe that an oil chamber is formed adjacently to a wall surface of a fixed sheave on the side opposite to a movable sheave to supply oil pressure to the oil chamber to resist the reaction force. However, these are disadvantageous since the configuration is complicated and parts must considerably be changed because the members are added for forming the oil chamber and an oil passage for supplying the oil pressure to the oil chamber.

The present invention was conceived in view of the situations and it is therefore an object of the present invention to provide a belt type continuously variable transmission for a vehicle capable of suppressing the fall of a fixed sheave without any additional parts.

Means for Solving the Problems

To achieve the object, the first aspect of the present invention provides a belt type continuously variable transmission for a vehicle (a) comprising: an input shaft and an output shaft disposed in parallel with each other; a pair of groove width variable pulleys disposed on the outer circumferential sides of the input shaft and the output shaft; and a transmission belt wound around each of V-grooves of the pair of the groove width variable pulleys, the belt type continuously variable transmission for a vehicle changing a winding diameter of the transmission belt by changing the groove widths of the V-grooves so as to continuously vary a gear ratio, wherein (b) the groove width variable pulley includes a fixed sheave fixed to an outer circumferential surface of one of the input shaft and the output shaft, and a movable sheave disposed relatively non-rotatably on the one shaft and relatively movably in the direction of the shaft center of the one shaft so as to form the V-groove with the fixed sheave, wherein (c) the belt type continuously variable transmission for a vehicle is disposed with a parking gear having a disc-shaped main body portion fixed to the one shaft on the side opposite to the movable sheave relative to the fixed sheave, and an annular projecting portion projecting from the main body portion toward a wall surface of the fixed sheave on the side opposite to the movable sheave and abutting on the wall surface of the opposite side on the outer circumferential side than the minimum winding diameter of the transmission belt, and wherein (d) the annular projecting portion of the parking gear abuts on the wall surface of the fixed sheave on the side opposite to the movable sheave at a radial position corresponding to the maximum winding diameter of the transmission belt.

The third aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in the first aspect of the present invention, wherein the annular projecting portion of the parking gear abuts on the wall surface, on the side opposite to the movable sheave, of the fixed sheave of the groove width variable pulley disposed on the output shaft.

The fourth aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in the first or third aspect of the present invention, wherein the annular projecting portion of the parking gear is fitted into and radially engaged with an annular fitting portion projected toward the parking gear from an outer circumferential portion of the wall surface of the fixed sheave on the side opposite to the movable sheave.

The fifth aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in any one of the first, third and fourth aspects of the present invention, wherein the annular projecting portion of the parking gear is circumferentially engaged with engagement teeth formed on the outer circumferential portion of the wall surface of the fixed sheave on the side opposite to the movable sheave.

The sixth aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in any one of the first, third to fifth aspects of the present invention, wherein the parking gear includes a stopper portion projected from the inner circumferential side of the annular projecting portion of the main body portion toward the wall surface of the fixed sheave on the side opposite to the movable sheave, and wherein when a pressing force preliminarily applied to the fixed sheave from the annular projecting portion to the fixed sheave reaches a predetermined value defined in advance, the stopper portion abuts on the wall surface of the opposite side to limit the application of the pressing force from the annular projecting portion to the fixed sheave.

The seventh aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in any one of the first, third to sixth aspects of the present invention, wherein the parking gear is tightened by a nut screwed to a shaft end portion of the one shaft and is clamped in the shaft center direction with the fixed sheave.

The eighth aspect of the present invention provides the belt type continuously variable transmission for a vehicle recited in any one of the first, third to seventh aspects of the present invention, wherein comprising an oil pressure chamber made of a space surrounded in an oil-tight manner by the main body portion and the annular projecting portion of the parking gear and the fixed sheave to generate the pressing force pressing the wall surface of the fixed sheave on the side opposite to the movable sheave toward the movable sheave when a predetermined oil pressure is supplied.

The Effects of the Invention

In the belt type continuously variable transmission for a vehicle recited in the first aspect of the present invention, the groove width variable pulley includes a fixed sheave fixed to an outer circumferential surface of one of the input shaft and the output shaft, and a movable sheave disposed relatively non-rotatably on the one shaft and relatively movably in the direction of the shaft center of the one shaft so as to form the V-groove for clamping the transmission belt with the fixed sheave, and wherein since the belt type continuously variable transmission for a vehicle is disposed with a parking gear having a disc-shaped main body portion fixed to the one shaft on the side opposite to the movable sheave relative to the fixed sheave, and an annular projecting portion projecting from the main body portion toward a wall surface of the fixed sheave on the side opposite to the movable sheave and abutting on the wall surface of the opposite side on the outer circumferential side than the minimum winding diameter of the transmission belt, even if the reaction force in the direction of the shaft center is applied from the transmission belt to the fixed sheave by clamping the transmission belt between the fixed sheave and the movable sheave, the wall surface of the fixed sheave on the side opposite to the transmission belt is supported on the outer circumferential side than the minimum winding diameter of the transmission belt by having only a relatively simple change of forming the annular projecting portion as compared to the parking gear conventionally used and, therefore, the fall of the fixed sheave can be suppressed without adding a part with a relatively simple configuration. And, since the annular projecting portion of the parking gear abuts on the wall surface of the fixed sheave on the side opposite to the movable sheave at a radial position corresponding to the maximum winding diameter of the transmission belt, even if the maximum reaction force in the direction of the shaft center is applied from the transmission belt to the fixed sheave by clamping the transmission belt located at the maximum winding diameter between the fixed sheave and the movable sheave, the annular projecting portion of the parking gear supports the position in the wall surface of the fixed sheave on the side opposite to the transmission belt corresponding to the point of action of the maximum reaction force in the direction of the shaft center, i.e., in the direction of action of the reaction force and, therefore, the fall of the fixed sheave can preferably be suppressed even when the maximum reaction force acts on the fixed sheave.

In the belt type continuously variable transmission for a vehicle recited in the third aspect of the present invention, since the annular projecting portion of the parking gear abuts on the wall surface, on the side opposite to the movable sheave, of the fixed sheave of the groove width variable pulley disposed on the output shaft, even if the reaction force in the direction of the shaft center is applied from the transmission belt to the fixed sheave fixed by the output shaft, the fixed sheave is supported by the parking gear conventionally fixed to the output shaft and, therefore, the fall of the fixed sheave can be suppressed without adding a part with a relatively simple configuration.

In the belt type continuously variable transmission for a vehicle recited in the fourth aspect of the present invention, since the annular projecting portion of the parking gear is fitted into and radially engaged with an annular fitting portion projected toward the parking gear from an outer circumferential portion of the wall surface of the fixed sheave on the side opposite to the movable sheave, even if the reaction force in the direction orthogonal to the shaft center is applied from the transmission belt to the fixed sheave by clamping the transmission belt between the fixed sheave and the movable sheave, the reaction force is applied to the parking gear and, therefore, the fall of the fixed sheave can be further suppressed.

In the belt type continuously variable transmission for a vehicle recited in the fifth aspect of the present invention, since the annular projecting portion of the parking gear is circumferentially engaged with engagement teeth formed on the outer circumferential portion of the wall surface of the fixed sheave on the side opposite to the movable sheave, when the non-rotating member engages with the parking gear for non-rotatably fixing the fixed shaft by the parking gear, the reaction force applied from the non-rotating member to the parking gear is applied to the engagement portion between the parking gear and the fixed sheave and, therefore, the fitting portion between the parking gear and the shaft can be shortened or eliminated in the direction of the shaft center. For example, when the parking gear is conventionally made by the spline fitting to the shaft, the length of the spline fitting portion can be shortened or eliminated in the direction of the shaft center. Therefore, since the forming cost of the fitting portion (spline fitting portion) can be reduced or eliminated and the length of the shaft can be shortened, the manufacturing cost of the belt type continuously variable transmission for a vehicle can be reduced.

In the belt type continuously variable transmission for a vehicle recited in the sixth aspect of the present invention, since the parking gear includes a stopper portion projected from the inner circumferential side of the annular projecting portion of the main body portion toward the wall surface of the fixed sheave on the side opposite to the movable sheave, and wherein when a pressing force preliminarily applied to the fixed sheave from the annular projecting portion to the fixed sheave reaches a predetermined value defined in advance, the stopper portion abuts on the wall surface of the opposite side to limit the application of the pressing force from the annular projecting portion to the fixed sheave, if the parking gear is fixed at the position where the stopper portion abuts on the wall surface on the opposite side, the pressing force (preload) toward the fixed sheave preliminarily applied to the parking gear can uniformly be set and the pressing force can easily be adjusted. Therefore, the pressing force can be adjusted by, for example, manual operation without using a special device such as a preload adjusting device.

In the belt type continuously variable transmission for a vehicle recited in the seventh aspect of the present invention, since the parking gear is tightened by a nut screwed to a shaft end portion of the one shaft and is clamped in the shaft center direction with the fixed sheave, the pressing force to the fixed sheave from the parking gear in the opposite to the direction of the action of the reaction force acts on the fixed sheave from the transmission belt is preliminarily applied to the fixed sheave and, therefore, the fall of the fixed sheave can preferably be suppressed even when the reaction force acts on the fixed sheave from the transmission belt.

In the belt type continuously variable transmission for a vehicle recited in the eighth aspect of the present invention, since an oil pressure chamber is included that is made of a space surrounded in an oil-tight manner by the main body portion and the annular projecting portion of the parking gear and the fixed sheave to generate the pressing force pressing the wall surface of the fixed sheave on the side opposite to the movable sheave toward the movable sheave when a predetermined oil pressure is supplied, even if the reaction force in the direction of the shaft center is applied from the transmission belt to the fixed sheave by clamping the transmission belt between the fixed sheave and the movable sheave, the pressing force is generated by the oil pressure chamber formed by having only a relatively simple change of forming the annular projecting portion as compared to the parking gear conventionally used and the fixed sheave and acts on the back surface of the fixed sheave to resist the reaction force and, therefore, the fall of the fixed sheave can be suppressed without adding a part with a relatively simple configuration.

The hydraulic cylinder included in the groove width variable pulley for moving the movable sheave of the groove width variable pulley disposed on the one shaft in the shaft center direction is configured to be actuated by an oil pressure supplied through the oil passage formed within the one shaft, and the oil pressure chamber is supplied with a portion of the oil pressure supplied to the hydraulic cylinder, through an oil pressure supply hole formed radially penetrating the inner circumferential side of the oil pressure chamber from the oil passage within the one shaft. As a result, the oil pressure can be supplied to the oil pressure chamber by making only a relatively simple change, i.e., by forming the oil pressure supply hole in the one shaft.

BEST MODES FOR CARRYING OUT THE INVENTION

One embodiment of the present invention will now be described in detail with reference to the drawings. In the following embodiments, the figures are simplified or deformed as needed for ease of description and are not necessarily accurately drawn in terms of dimensional ratios, shapes, etc., of portions.

First Embodiment

FIG. 1is a schematic of a vehicle power transmission device10to which the present invention is preferably applied. InFIG. 1, the vehicle power transmission device10is for an FF (front-engine front-drive) vehicle and is coupled to an engine12well-known as a vehicle drive source. The vehicle power transmission device10includes a torque converter14well-known as a hydraulic power transmission using fluid as a medium to transmit the torque of the engine12; a forward/reverse switching device16switching a rotation direction of the torque transmitted from the torque converter14between the rotation direction for forward running of a vehicle and the opposite direction thereof; i.e., the inverse rotation direction for reverse running of a vehicle; a belt type continuously variable transmission for a vehicle (hereinafter referred to as a continuously variable transmission)18converting the torque transmitted via the forward/reverse switching device16into a torque corresponding to a load; a reduction gear device20coupled to the output side of the continuously variable transmission18; and a well-known so-called bevel gear type differential gear device24transmitting the torque transmitted via the reduction gear device20to a pair of left and right wheels22while allowing a rotation difference thereof. A pump impeller26of the torque converter14is disposed with a mechanical oil pump28generating an oil pressure etc., used for the shift control of the continuously variable transmission18and the forward/reverse switching control of the forward/reverse switching device16, for example.

The forward/reverse switching device16is mainly made up of a double pinion type planetary gear device including a sun gear32coupled to a turbine shaft30of the torque converter14in a power transmittable manner, a carrier36coupled to an input shaft34of the continuously variable transmission18and selectively coupled via a forward clutch C to the turbine shaft30, and a ring gear40selectively coupled via a reverse brake B to a transaxle case38housing the forward/reverse switching device16, the continuously variable transmission18, the differential gear device24, etc. Both the forward clutch C and the reverse brake B are hydraulic friction engagement devices caused to be frictionally engaged by supplying an oil pressure from the oil pump28.

In the forward/reverse switching device16, the planetary gear device is put into the integrally rotating state by engaging the forward clutch C and releasing the reverse brake B and a forward power transmission path is established. If the forward power transmission path is established, the torque transmitted from the torque converter14is transmitted to the continuously variable transmission18without changing the rotation direction. In the forward/reverse switching device16, the planetary gear device is put into the input/output inversely rotating state by engaging the reverse brake B and releasing the forward clutch C and a reverse power transmission path is established. If the reverse power transmission path is established, the torque transmitted from the torque converter14is transmitted to the continuously variable transmission18with the rotation direction reversed. By releasing both the forward clutch C and the reverse brake B, the forward/reverse switching device16is put into a neutral state (interrupted state) in which the power transmission is interrupted.

FIG. 2is a cross-sectional view of a configuration of the continuously variable transmission18of one embodiment of the present invention in the vehicle power transmission device10ofFIG. 1. InFIG. 2, the continuously variable transmission18includes the input shaft34rotatably supported around a shaft center C1via a pair of bearings42by the transaxle case38; a primary pulley (groove width variable pulley)46disposed on the outer circumferential side of the input shaft34; an output shaft50disposed in parallel with the input shaft34and rotatably supported around a shaft center C2via a pair of bearings48by the transaxle case38; a secondary pulley (groove width variable pulley)52disposed on the outer circumferential side of the input shaft34; and a well-known endless annular transmission belt56wound around each of V-grooves54of the primary pulley46and the secondary pulley52to transmit power through a frictional force between the both pulleys. Out of the pair of the bearings42and the pair of the bearings48, the bearing42and the bearing48fitted into the inner circumferential surface of the transaxle case38on the side opposite to the forward/reverse switching device16depicted inFIG. 1are respectively prevented from moving in the directions of the shaft centers C1and C2by annular disc-shaped fixed plates55and57each fixed by a bolt to the transaxle case38.

The primary pulley46includes a fixed sheave58fixed to the outer circumferential side of the input shaft34; a movable sheave60disposed relatively non-rotatably on the input shaft34and relatively movably in the direction of the shaft center C1of the input shaft34so as to form the V-groove54with the fixed sheave58; and a hydraulic actuator62moving the movable sheave60in the direction of the shaft center C1depending on a supplied oil pressure and making the movable sheave60and the fixed sheave58closer or further to each other so as to vary the groove width of the V-groove54. The secondary pulley52includes a fixed sheave64fixed to the outer circumferential side of the output shaft50; a movable sheave66disposed relatively non-rotatably on the output shaft50and relatively movably in the direction of the shaft center C2of the output shaft50so as to form the V-groove54with the fixed sheave64; and a hydraulic actuator68moving the movable sheave66in the direction of the shaft center C2depending on a supplied oil pressure and making the movable sheave66and the fixed sheave64closer or further to each other so as to vary the groove width of the V-groove54. The primary pulley46and the secondary pulley52are groove width variable pulleys having the same configuration except that the hydraulic actuator68of the secondary pulley52is of a single piston type while the hydraulic actuator62of the primary pulley46is of a double piston type and that the hydraulic actuator68of the secondary pulley52is disposed with a coil spring70always biasing the movable sheave66toward the fixed sheave64while the hydraulic actuator62of the primary pulley46is not disposed with such a spring. The secondary pulley52will hereinafter be described in detail as a representative of the primary pulley46and the secondary pulley52.

The fixed sheave64is an annular disc-shaped member integrally disposed on the output shaft50and projecting from the outer circumferential surface of the output shaft50toward the outer circumferential side. The fixed sheave64has a taper surface72formed on a surface facing the movable sheave60with a distance from the movable sheave60increasing toward the outer circumferential side.

The movable sheave66has an inner cylindrical portion66afitted to the output shaft50relatively movably in the direction of the shaft center C2in a ball spline method and relatively non-rotatably around the shaft center C2; a disc portion66bthat is an annular disc-shaped member integrally disposed and projecting from one end portion of the cylindrical portion66acloser to the fixed sheave64toward the outer circumferential side and that has a taper surface74on a surface facing the fixed sheave64with a distance from the fixed sheave64increasing toward the outer circumferential side; and an outer cylindrical portion66cprojected from the outer circumferential portion of the disc portion66btoward the side opposite to the fixed sheave64in the direction of the shaft center C2. The taper surface74forms the V-shaped V-groove54with the taper surface72of the fixed sheave64.

The hydraulic actuator68includes a cylinder member76having an inner circumferential wall portion76alocated at one end portion of the output shaft50on the side opposite to the fixed sheave64relative to the movable sheave66and having an inner circumferential portion sandwiched between a stepped end surface of the one end portion and the bearing48; a cylindrical portion76bextended from the outer circumferential portion of the inner circumferential wall portion76atoward the disc portion66bof the movable sheave66; and an outer circumferential wall portion76cprojected from one end portion of the cylindrical portion76bcloser to the movable sheave66continuously in a circumferential direction toward the outer circumference and sliding via an oil seal on the inner circumferential surface of the outer cylindrical portion66cof the movable sheave66. An oil pressure chamber78is formed in a space surrounded in an oil-tight manner by the cylinder member76, the movable sheave66, and the output shaft50. The oil pressure chamber78is supplied with oil pressure through each of a first oil passage80formed in the transaxle case38and supplied with an oil pressure via a hydraulic control device not depicted adjusting the oil pressure generated by the oil pump28; a second oil passage82formed on the inner circumferential side of the output shaft50; and a third oil passage84formed to radially penetrate the output shaft50. The coil spring70is disposed between a stepped end surface formed on the outer circumferential surface of the inner cylindrical portion66aof the movable sheave66and a stepped end surface formed on the inner circumferential surface of the cylindrical portion76bof the cylinder member76.

In this secondary pulley52, the movable sheave66moves closer to or further away from the fixed sheave64in the direction of the shaft center C1depending on the oil pressure supplied to the oil pressure chamber78to change the width of the V-groove54. InFIG. 2, the movable sheave66indicated by a solid line on the lower side of the shaft center C2indicates the state of the minimum width of the V-groove54formed with the fixed sheave64. In this state, the winding diameter of the transmission belt56is maximized. The movable sheave66indicated by a solid line on the upper side and by a dashed-two dotted line on the lower side of the shaft center C2indicates the state of the maximum width of the V-groove54formed with the fixed sheave64. In this state, the winding diameter of the transmission belt56is minimized.

FIG. 3is an enlarged cross-sectional view of the secondary pulley52and one end portion of the output shaft50of the continuously variable transmission18ofFIG. 2. InFIG. 3, a parking gear86for non-rotatably fixing the output shaft50is fixed to the output shaft50between the secondary pulley52and the bearing48. The parking gear86has a disc-shaped main body portion86afixed by, for example, the spline fitting to the output shaft50on the side opposite to the movable sheave66relative to the fixed sheave64, and an annular projecting portion86bprojecting from the main body portion86atoward the wall surface of the fixed sheave64on the side opposite to the movable sheave66, i.e., a back surface90, and abutting on the back surface90at a radial position corresponding to the maximum winding diameter of the transmission belt56. On the outer circumferential surface of the main body portion86a, outer circumferential teeth88are formed that are engageable with a parking pole not depicted disposed on a non-rotating member such as the transaxle case38, for example. The output shaft50is fixed non-rotatably around the shaft center C2by engaging the parking pole with the outer circumferential teeth88of the parking gear86.

The parking gear86is clamped in the direction of the shaft center C2between the bearing48and the fixed sheave64by tightening a nut92screwed to a shaft end portion of the output shaft50on the side opposite to the parking gear86relative to the bearing48while the main body portion86ais fitted to one end portion of the output shaft50in a state of interference fitting or loose fitting, for example, and interposed between the bearing48and the fixed sheave64in the direction of the shaft center C2. As a result, a pressing force (preload) from the annular projecting portion86bof the parking gear86toward the fixed sheave64is preliminarily applied to the fixed sheave64. This pressing force is adjusted to a predetermined value defined in advance, for example, in accordance with a preliminarily empirically obtained relationship between a tightening torque of the nut92and the pressing force, by adjusting the tightening torque. The predetermined value is set to a larger value as much as possible within a range in which the fixed sheave64is not deformed toward the movable sheave66, for example. The annular projecting portion86bof the parking gear86of this embodiment is different from an annular projecting portion104bof a conventional parking gear104depicted inFIG. 10in that the annular projecting portion86bis formed on the outer circumferential side.

In the continuously variable transmission18configured as above, the groove widths of the V-grooves54of the primary pulley46and the secondary pulley52are respectively changed and the clamping force to the transmission belt56is adjusted by adjusting and controlling a primary oil pressure supplied to the hydraulic actuator62of the primary pulley46with the hydraulic control device and by adjusting and controlling a secondary oil pressure supplied to the hydraulic actuator68of the secondary pulley52with the hydraulic control device. When the groove widths of the V-grooves54of the primary pulley46and the secondary pulley52are changed as described above, the winding diameter of the transmission belt56is changed and a rotation speed ratio (gear ratio) of the input shaft34and the output shaft50varies in a stepless manner. For example, on the upper side of the shaft center C1and the lower side of the shaft center C2ofFIG. 2, the transmission belt56indicated by solid lines indicates the state of the gear radio of the continuously variable transmission18set to the maximum gear ratio when the winding diameter at the primary pulley46is the minimum value and the winding diameter at the secondary pulley52is the maximum value. InFIG. 2, the transmission belt56indicated by dashed-two dotted lines indicates the state of the gear radio of the belt type continuously variable transmission18set to the minimum gear ratio when the winding diameter at the primary pulley46is the maximum value and the winding diameter at the secondary pulley52is the minimum value.

The fixed sheave64and the movable sheave66of the secondary pulley52apply a clamping force in the direction of the shaft center C2to the transmission belt56while a reaction force from the transmission belt56is applied thereto. As depicted inFIG. 3, the fixed sheave64is affected by a moment M causing the fixed sheave64to fall toward the side opposite to the movable sheave66with a base portion, i.e., an inner circumferential potion of the fixed sheave64used as a fulcrum due to a shaft-center-direction reaction force Fc2that is a component in the direction of the shaft center C2of a reaction force F applied from the transmission belt56. The reaction force and the moment M are maximized when the winding diameter of the transmission belt56is maximized as indicated by solid line inFIG. 3. The parking gear86abuts on the back surface90of the fixed sheave64on the side of falling of the fixed sheave64due to the moment M. To the fixed sheave64, the pressing force acting in the opposite direction of the shaft-center-direction reaction force Fc2is preliminarily applied. Additionally, the pressing force is applied to a position in the back surface90of the fixed sheave64at the point of action and against the direction of action of the maximum shaft-center-direction reaction force Fc2applied from the transmission belt56to the fixed sheave64. Therefore, the parking gear86of this embodiment functions as a member supporting the fixed sheave64to resist the shaft-center-direction reaction force Fc2(bending moment M).

In the continuously variable transmission18of this embodiment, the secondary pulley (groove width variable pulley)52includes the fixed sheave64fixed to the outer circumferential surface of the output shaft50(one of the input shaft and the output shaft) and the movable sheave66disposed relatively non-rotatably around the shaft center C2and relatively movably in the direction of the shaft center C2on the output shaft50so as to form the V-groove54for clamping the transmission belt56with the fixed sheave64and since the parking gear86is disposed that has the disc-shaped main body portion86afixed by, for example, the spline fitting to the output shaft50on the side opposite to the movable sheave66relative to the fixed sheave64and the annular projecting portion86bprojecting from the main body portion86atoward the wall surface of the fixed sheave64on the side opposite to the movable sheave66, i.e., the back surface90, and abutting on the back surface90at a radial position corresponding to the maximum winding diameter of the transmission belt56, even if the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave64by clamping the transmission belt56between the fixed sheave64and the movable sheave66, the back surface90of the fixed sheave64on the side opposite to the transmission belt56is supported on the outer circumferential side than the minimum winding diameter of the transmission belt56by the parking gear86having only a relatively simple change of forming the annular projecting portion86bas compared to those conventionally fixed to the output shaft50and, therefore, the fall of the fixed sheave64can be suppressed without adding a part with a relatively simple configuration.

In the continuously variable transmission18of this embodiment, since the annular projecting portion86bof the parking gear86abuts on the back surface90of the fixed sheave64at a radial position corresponding to the maximum winding diameter of the transmission belt56, even if the maximum shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave64by clamping the transmission belt56located at the maximum winding diameter between the fixed sheave64and the movable sheave66, the annular projecting portion86bof the parking gear86supports the position in the back surface90of the fixed sheave64corresponding to the point of action of the maximum shaft-center-direction reaction force Fc2in the direction of action of the shaft-center-direction reaction force Fc2and, therefore, the fall of the fixed sheave64can preferably be suppressed even when the maximum shaft-center-direction reaction force Fc2acts on the fixed sheave64.

In the continuously variable transmission18of this embodiment, since the parking gear86is clamped in the direction of the shaft center C2with the fixed sheave64by tightening the nut92screwed to the shaft end portion of the output shaft50and the pressing force (preload) from the parking gear86toward the fixed sheave64, i.e., a force in the opposite direction of the shaft-center-direction reaction force Fc2is preliminarily applied to the fixed sheave64, the fall of the fixed sheave64can preferably be suppressed even when the shaft-center-direction reaction force Fc2toward the parking gear86acts on the fixed sheave64.

In the continuously variable transmission18of this embodiment, since the pressing force preliminarily applied from the parking gear86to the fixed sheave64is set to a larger value as much as possible within a range in which the fixed sheave64is not deformed toward the movable sheave66, the fall of the fixed sheave64can preferably be suppressed while the power transmission efficiency is prevented from deteriorating because of the deformation of the fixed sheave64toward the movable sheave66due to the pressing force.

FIG. 10is a cross-sectional view of a secondary pulley102and the parking gear104in a conventional continuously variable transmission100, corresponding toFIG. 3of the first embodiment. As depicted inFIG. 10, in the conventional parking gear104, the annular projecting portion104babuts on a base portion of a fixed sheave106, i.e., a radial position on the inner circumferential side than the minimum winding diameter of the transmission belt56in a back surface108of the fixed sheave106. Therefore, if the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave106by clamping the transmission belt56between the fixed sheave106and the movable sheave66of the secondary pulley102, since the fixed sheave106falls toward the side opposite to the movable sheave66as indicated by an arrow A inFIG. 11, the contact area between the fixed sheave106and the transmission belt56is problematically reduced, deteriorating the power transmission efficiency. Therefore, the thickness of the fixed sheave106is increased in the direction of the shaft center C2to improve the strength as a countermeasure in the conventional continuously variable transmission100; however, this is disadvantageous because the material cost of the fixed sheave106increases along with an increase in the manufacturing cost of the continuously variable transmission100and the weight of the continuously variable transmission100increases.

On the other hand, in the continuously variable transmission18of this embodiment, since the back surface90of the fixed sheave64is supported by the annular projecting portion86bof the parking gear86, the fall of the fixed sheave64can be suppressed even if the thickness of the fixed sheave64in the direction of the shaft center C2is reduced as compared to the conventional fixed sheave106indicated by dashed-two dotted lines ofFIG. 3. Therefore, as compared to the conventional continuously variable transmission100, this is advantageous because the material cost of the fixed sheave64decreases along with decrease in the manufacturing cost of the continuously variable transmission18and the weight of the continuously variable transmission18is reduced.

Second Embodiment

Other embodiments of the present invention will be described. In the following description of the embodiments, the portions of the embodiments overlapping with each other are denoted by the same reference numerals and will not be described.

FIG. 4is an enlarged cross-sectional view of a secondary pulley202and a parking gear204of a continuously variable transmission200of another embodiment of the present invention. As depicted inFIG. 4, a fixed sheave206of the secondary pulley202includes an annular fitting portion206aprojected from an outer circumferential portion of a back surface208on the side opposite to the movable sheave66toward the parking gear204. The parking gear204includes an annular disc-shaped main body portion204afixed to an outer circumferential surface of the output shaft50, and an annular projecting portion204bprojected from the main body portion204atoward the fixed sheave206and fitted into and radially engaged with the annular fitting portion206aof the fixed sheave206. The parking gear204is clamped in the direction of the shaft center C2between the bearing48and the fixed sheave206by tightening the nut92screwed to the shaft end portion of the output shaft50on the side opposite to the parking gear204relative to the bearing48while the main body portion204ais fitted to one end portion of the output shaft50in a state of interference fitting or loose fitting, for example, and interposed between the bearing48and the fixed sheave206in the direction of the shaft center C2. As a result, a pressing force (preload) from the parking gear204toward the fixed sheave206is applied to the fixed sheave206. This pressing force is adjusted to a predetermined value defined in advance, for example, in accordance with a preliminarily empirically obtained relationship between the tightening torque of the nut92and the pressing force by adjusting the tightening torque. The predetermined value is set to a larger value as much as possible within a range in which the fixed sheave206is not deformed toward the movable sheave66, for example. The preliminary application of the pressing force (preload) from the parking gear204to the fixed sheave206by tightening the nut92screwed to the shaft end portion of the output shaft50as described above is the same in parking gears of the following third to fifth embodiments and will not be described in the following embodiments.

In the continuously variable transmission200configured as above, the fixed sheave206is affected by the moment M causing the fixed sheave206to fall toward the side opposite to the movable sheave66with a base portion, i.e., an inner circumferential portion of the fixed sheave206used as a fulcrum due to the shaft-center-direction reaction force Fc2applied from the transmission belt56. The parking gear204abuts on the back surface208of the fixed sheave206on the side of falling of the fixed sheave206due to the moment M. To the fixed sheave206, the pressing force acting in the opposite direction of the shaft-center-direction reaction force Fc2is preliminarily applied. Additionally, the pressing force is applied to a position in the back surface208of the fixed sheave206at the point of action and against the direction of action of the maximum shaft-center-direction reaction force Fc2applied from the transmission belt56to the fixed sheave206. Therefore, the parking gear204of this embodiment functions as a member supporting the fixed sheave206to resist the shaft-center-direction reaction force Fc2(bending moment M).

Even if the moment causing the fall toward the side opposite to the movable sheave66is applied to the fixed sheave206due to the reaction force F applied from the transmission belt56, the parking gear204radially supports the inner circumferential surface of the annular fitting portion206aof the fixed sheave206with the annular projecting portion204bof the parking gear204on the falling side. The parking gear204of this embodiment functions as a radially supporting member resisting a radial reaction force Fr that is a component in the direction orthogonal to the shaft center C2of the reaction force F so as to prevent the fixed sheave206from falling.

In the continuously variable transmission200of this embodiment, since the parking gear204is disposed that has the disc-shaped main body portion204afixed to the output shaft50on the side opposite to the movable sheave66relative to the fixed sheave206and the annular projecting portion204bprojecting from the main body portion204atoward the wall surface of the fixed sheave206on the side opposite to the movable sheave66, i.e., the back surface208, and abutting on the back surface208at a radial position corresponding to the maximum winding diameter of the transmission belt56, even if the maximum shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave206by clamping the transmission belt56located at the maximum winding diameter between the fixed sheave206and the movable sheave66, the annular projecting portion204bof the parking gear204supports the position in the back surface208of the fixed sheave206corresponding to the point of action of the maximum shaft-center-direction reaction force Fc2and the direction of action of the shaft-center-direction reaction force Fc2and, therefore, the fall of the fixed sheave206can be suppressed without adding a part with a relatively simple configuration as is the case with the first embodiment.

In the continuously variable transmission200of this embodiment, since the annular projecting portion204bof the parking gear204is fitted into and radially engaged with the annular fitting portion206aprojected from the outer circumferential portion of the back surface208of the fixed sheave206toward the parking gear204, the radial reaction force Fr in the direction orthogonal to the shaft center C2applied from the transmission belt56to the fixed sheave206by clamping the transmission belt56between the fixed sheave206and the movable sheave66is transmitted via the fixed sheave206and the parking gear204to the output shaft50and is distributed and applied in the direction of the shaft center C2as compared to the case of the radial reaction force Fr transmitted only via the fixed sheave206and, therefore, the bending of the output shaft50due to the radial reaction force Fr can preferably be suppressed. Even if the radial dimension of the output shaft50is reduced, the bending rigidity equal to or more than the case of the radial reaction force Fr transmitted only via the fixed sheave206can be ensured and, therefore, the weight of the output shaft50can be reduced.

Third Embodiment

FIG. 5is an enlarged cross-sectional view of a secondary pulley302and a parking gear304of a continuously variable transmission300of another embodiment of the present invention. As depicted inFIG. 5, a fixed sheave306of the secondary pulley302has a stepped end surface310formed on an inner circumferential portion of a back surface308on the side opposite to the movable sheave66. The parking gear304includes a main body portion304aand an annular projecting portion304bsame as the main body portion86aand the annular projecting portion86bof the parking gear86of the first embodiment, and a stopper portion304cprojected from the inner circumferential side of the annular projecting portion304bof the main body portion304atoward the stepped end surface310of the back surface308. The stopper portion304cabuts on the stepped end surface310of the back surface308when the pressing force applied from the annular projecting portion304bof the parking gear304to the fixed sheave306reaches a predetermined value defined in advance, so as to limit the application of the pressing force from the annular projecting portion304bto the fixed sheave306. The predetermined value is set to a larger value as much as possible within a range in which the fixed sheave306is not deformed toward the movable sheave66, for example. AlthoughFIG. 5depicts a state in which a gap is formed in the direction of the shaft center C2between the stopper portion304cand the stepped end surface310, this represents a stage in the middle of assembly and the stopper portion304cand the stepped end surface310are actually brought into contact with each other in the direction of the shaft center C2to apply the pressing force of the predetermined value defined in advance from the annular projecting portion304bto the fixed sheave306as described above.

In the continuously variable transmission300configured as above, the parking gear304functions as a member supporting the fixed sheave306to resist the shaft-center-direction reaction force Fc2(bending moment M) as is the case with the first embodiment.

The constituent elements other than those described above are the same as the first embodiment and, in the continuously variable transmission300of this embodiment, the fall of the fixed sheave306can be suppressed without adding a part with a relatively simple configuration as is the case with the first embodiment.

In the continuously variable transmission300of this embodiment, since the parking gear304includes the stopper portion304cprojected from the inner circumferential side of the annular projecting portion304bof the main body portion304atoward the stepped end surface310of the back surface308, and the stopper portion304cabuts on the stepped end surface310of the back surface308when the pressing force applied from the annular projecting portion304bof the parking gear304to the fixed sheave306reaches a predetermined value defined in advance, so as to limit the application of the pressing force from the annular projecting portion304bto the fixed sheave306, if the parking gear304is fixed at the position where the stopper portion304cabuts on the stepped end surface310of the back surface308, the pressing force (preload) preliminarily applied from the parking gear304to the fixed sheave306can uniformly be set and the pressing force can easily be adjusted. Therefore, the pressing force can be adjusted by, for example, manual operation without using a special device such as a preload adjusting device.

Since the parking gear304is clamped in the direction of the shaft center C2with the fixed sheave306by tightening the nut92screwed to the shaft end portion of the output shaft50to which the parking gear304is fixed, the pressing force from the parking gear304to the fixed sheave306can be applied as a predetermined value defined in advance by only tightening the nut92until reaching a predetermined tightening torque empirically defined in advance at which the stopper portion304cof the parking gear304abuts on the stepped end surface310of the back surface308of the fixed sheave306and, therefore, the pressing force can easily be adjusted.

Fourth Embodiment

FIG. 6is an enlarged cross-sectional view of a secondary pulley402and a parking gear404of a continuously variable transmission400of another embodiment of the present invention. As depicted inFIG. 6, a fixed sheave406of the secondary pulley402has a plurality of first spline teeth (engagement teeth)410each extending radially around the shaft center C2and formed sequentially in a circumferential direction in a portion including a radial position corresponding to the maximum winding diameter of the transmission belt56in an outer circumferential portion of a back surface408on the side opposite to the movable sheave66. Although the first spline teeth410of this embodiment are, for example, involute splines, other splines may be available. The parking gear404has a main body portion404asame as the main body portion86aof the parking gear86of the first embodiment, and an annular projecting portion404bprojected from the main body portion404atoward the back surface408of the fixed sheave406and abutting on the fixed sheave406at a radial position in the back surface408corresponding to the maximum winding diameter of the transmission belt56. The parking gear404abuts in the direction of the shaft center C2on and circumferentially engages with the fixed sheave406via a plurality of second spline teeth412each formed radially around the shaft center C2in the leading portion of the annular projecting portion404band respectively engaging with a plurality of the first spline teeth410.

In the continuously variable transmission400configured as above, the parking gear404functions as a member supporting the fixed sheave406to resist the shaft-center-direction reaction force Fc2(bending moment M) as is the case with the first embodiment.

In this embodiment, the torque of the output shaft50is transmitted to the parking gear404via the engagement portion between the first spline teeth410and the second spline teeth412in addition to the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear404. As compared to the case of transmitting the torque of the output shaft50to the parking gear104via only the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear104as in the conventional case depicted inFIG. 10, a length L in the direction of the shaft center C2of the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear404of this embodiment is reduced by a length L1.

The constituent elements other than those described above are the same as the first embodiment and, in the continuously variable transmission400of this embodiment, the fall of the fixed sheave406can be suppressed without adding a part with a relatively simple configuration as is the case with the first embodiment.

In the continuously variable transmission400of this embodiment, since the annular projecting portion404bof the parking gear404is circumferentially engaged via the second spline teeth412with the first spline teeth (engagement teeth)410formed on the outer circumferential portion of the wall surface of the fixed sheave406on the side opposite to the movable sheave66, i.e., the back surface408, when the parking pole engages with the outer circumferential teeth88of the parking gear404for non-rotatably fixing the output shaft50, the reaction force, i.e., torque, applied from the parking pole to the parking gear404is also applied to the engagement portion between the parking gear404and the fixed sheave406in addition to the engagement portion between the parking gear404and the output shaft50and, therefore, even if the length L of the engagement portion between the parking gear404and the output shaft50is shortened in the direction of the shaft center C2, the strength equal to or more than the conventional case can be ensured for resisting the reaction force applied from the parking pole. Since the engagement portion between the first spline teeth410and the second spline teeth412is disposed on the outer circumferential side than the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear404, the strength equal to or more than the conventional case can preferably be ensured for resisting the reaction force applied from the parking pole. Therefore, since the forming cost of the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear404can be reduced and the length of the output shaft50can be shortened by the reduced length L1of the spline fitting portion, the manufacturing cost of the continuously variable transmission400can be reduced.

Fifth Embodiment

FIG. 7is an enlarged cross-sectional view of a secondary pulley502and a parking gear504of a continuously variable transmission500of another embodiment of the present invention. As depicted inFIG. 7, a fixed sheave506of the secondary pulley502includes an annular fitting portion506aprojected from an outer circumferential portion of a back surface508on the side opposite to the movable sheave66toward the fixed sheave506, and the inner circumferential surface of the annular fitting portion506ahas a plurality of first spline teeth (engagement teeth)510each extending in the direction of the shaft center C2and formed sequentially in a circumferential direction. Although the first spline teeth510of this embodiment are, for example, involute splines, other splines may be available. The parking gear504has an annular disc-shaped main body portion504ahaving an inner circumferential surface fitted to the outer circumferential surface of the output shaft50, and an annular projecting portion504bprojected from the main body portion504atoward a back surface508of the fixed sheave506and abutting on the fixed sheave506at a radial position of the back surface508corresponding to the maximum winding diameter of the transmission belt56. The parking gear504circumferentially engages with the fixed sheave506via a plurality of second spline teeth512each extended in the direction of the shaft center C2in the outer circumferential surface of the leading portion of the annular projecting portion504band respectively engaging with a plurality of the first spline teeth510.

In the continuously variable transmission500configured as above, the parking gear504functions as a member supporting the fixed sheave506to resist the shaft-center-direction reaction force Fc2(bending moment M) as is the case with the first embodiment. Even if the moment causing the fall toward the side opposite to the movable sheave66is applied to the fixed sheave506due to the reaction force F applied from the transmission belt56, the parking gear504radially supports the annular fitting portion506aof the fixed sheave206with the annular projecting portion204bof the parking gear504on the falling side. The parking gear504of this embodiment functions as a radially supporting member resisting a radial reaction force Fr that is a component in the direction orthogonal to the shaft center C2of the reaction force F so as to prevent the fixed sheave506from falling.

In this embodiment, the torque of the output shaft50is transmitted to the parking gear504via the engagement portion between the first spline teeth510and the second spline teeth512. The engagement portion between the first spline teeth410and the second spline teeth412is disposed on the outer circumferential side than the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear104formed in the conventional case depicted inFIG. 10, and when the parking pole engages with the outer circumferential teeth88of the parking gear504for non-rotatably fixing the output shaft50, the strength equal to or more than the conventional case is ensured for resisting the reaction force applied from the parking pole to the parking gear504.

The constituent elements other than those described above are the same as the first embodiment and, in the continuously variable transmission500of this embodiment, the fall of the fixed sheave506can be suppressed without adding a part with a relatively simple configuration as is the case with the first embodiment.

In the continuously variable transmission500of this embodiment, since the annular projecting portion504bof the parking gear504is circumferentially engaged via the second spline teeth512with the first spline teeth (engagement teeth)510formed on the outer circumferential portion of the wall surface of the fixed sheave506on the side opposite to the movable sheave66, i.e., the back surface508, the conventionally disposed spline fitting portion between the parking gear504and the output shaft50can be eliminated. Since the engagement portion between the first spline teeth410and the second spline teeth412is disposed on the outer circumferential side than the spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear104formed in the conventional case depicted inFIG. 10, when the parking pole engages with the outer circumferential teeth88of the parking gear504for non-rotatably fixing the output shaft50, the strength equal to or more than the conventional case can be ensured for resisting the reaction force applied from the parking pole to the parking gear504. Therefore, since the forming cost of the conventionally disposed spline fitting portion between the outer circumferential surface of the output shaft50and the inner circumferential surface of the parking gear104can be cut and the length of the output shaft50can be shortened by the reduction in length of the parking gear504in the direction of shaft center C2, the manufacturing cost of the continuously variable transmission500can be reduced.

Since the annular projecting portion204bof the parking gear504radially supports the annular fitting portion506aof the fixed sheave206, the bending rigidity is enhanced in the output shaft50and the members fixed thereto as a whole. Therefore, the bending rigidity equal to or more than the conventional case can be ensured if the diameter of the output shaft50is reduced.

Sixth Embodiment

FIG. 8is an enlarged cross-sectional view of the secondary pulley52and a parking gear602of a continuously variable transmission600of another embodiment of the present invention. As depicted inFIG. 8, the parking gear602has a main body portion602asame as the main body portion86aof the parking gear86of the first embodiment, an annular projecting portion602bprojected from the outer circumferential portion of the main body portion602atoward a radial position in the back surface90of the fixed sheave64corresponding to the maximum winding diameter of the transmission belt56, and an O-ring606fitted into an annular O-ring groove604formed in a surface of the annular projecting portion602bfacing the back surface90. The O-ring606is made of oil resistant synthetic rubber, for example, and is disposed in close contact with each of the bottom surface of the O-ring groove604and the back surface90. The annular projecting portion602bof the parking gear602abuts on the fixed sheave64via the O-ring606. As a result, the inner circumferential side of the annular projecting portion602bis provided with an oil pressure chamber608consisting of an annular space surrounded in an oil-tight manner by the main body portion602aand the annular projecting portion602bof the parking gear602and the fixed sheave64. The oil pressure chamber608is supplied with a predetermined oil pressure from the second oil passage82through an oil pressure supply hole610radially penetrating the inner circumferential side of the oil pressure chamber608from the second oil passage82in the output shaft55to generate a pressing force pressing the wall surface of the fixed sheave64on the side opposite to the movable sheave66, i.e., the back surface90, toward the movable sheave66. The oil pressure supplied to the oil pressure chamber608is a portion of the secondary oil pressure adjusted and controlled by the hydraulic control device and supplied to the hydraulic actuator68depicted inFIG. 2.

In the continuously variable transmission600configured as above, when the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave64by clamping the transmission belt56between the fixed sheave64and the movable sheave66, the fixed sheave64is affected by the moment M causing the fixed sheave64to fall toward the side opposite to the movable sheave66with the base portion, i.e., the inner circumferential portion of the fixed sheave64used as a fulcrum. In this case, the pressing force generated by supplying the secondary oil pressure to the oil pressure chamber608acts on the back surface90of the fixed sheave64in the opposite direction of the shaft-center-direction reaction force Fc2to resist the shaft-center-direction reaction force Fc2(bending moment M).

In the continuously variable transmission600of this embodiment, since the parking gear602is included that has a disc-shaped main body portion602afixed to the output shaft50on the side opposite to the movable sheave66relative to the fixed sheave64, the annular projecting portion602bprojected from the outer circumferential portion of the main body portion602atoward the radial position in the back surface90of the fixed sheave64corresponding to the maximum winding diameter of the transmission belt56, and the O-ring606fitted into the annular O-ring groove604formed in the surface of the annular projecting portion602bfacing the back surface90, and the oil pressure chamber608is included that is made of a space surrounded in an oil-tight manner by the main body portion602aand the annular projecting portion602bof the parking gear602and the fixed sheave64to generate a hydraulic force pressing the wall surface of the fixed sheave64on the side opposite to the movable sheave66, i.e., the back surface90, toward the movable sheave66when the secondary oil pressure adjusted and controlled by the hydraulic control device is supplied, even if the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave64by clamping the transmission belt56between the fixed sheave64and the movable sheave66, the pressing force is generated by the oil pressure chamber608formed with the parking gear602having only a relatively simple change from those conventionally used and the fixed sheave and acts on the back surface90of the fixed sheave64to resist the shaft-center-direction reaction force Fc2and, therefore, the fall of the fixed sheave64can be suppressed without adding a part with a relatively simple configuration.

Seventh Embodiment

FIG. 9is an enlarged cross-sectional view of a secondary pulley702and a parking gear602of a continuously variable transmission700of another embodiment of the present invention. As depicted inFIG. 9, a fixed sheave704of the secondary pulley702includes an annular fitting portion704aprojected from an outer circumferential portion of a wall surface on the side opposite to the movable sheave66, i.e., the back surface706, toward the parking gear602. The annular projecting portion602bof the parking gear602is fitted into and radially engaged with the annular fitting portion704aof the fixed sheave704. The oil pressure chamber608is supplied with a predetermined oil pressure from the second oil passage82through the oil pressure supply hole610radially penetrating the inner circumferential side of the oil pressure chamber608from the second oil passage82in the output shaft55to generate a pressing force pressing the back surface706of the fixed sheave64toward the movable sheave66. The oil pressure supplied to the oil pressure chamber608is a portion of the secondary oil pressure adjusted and controlled by the hydraulic control device and supplied to the hydraulic actuator68depicted inFIG. 2.

In the continuously variable transmission700configured as above, when the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave704by clamping the transmission belt56between the fixed sheave704and the movable sheave66, the fixed sheave704is affected by the moment M causing the fixed sheave704to fall toward the side opposite to the movable sheave66with the base portion, i.e., the inner circumferential portion of the fixed sheave704used as a fulcrum. In this case, the pressing force generated by supplying the secondary oil pressure to the oil pressure chamber608acts on the back surface706of the fixed sheave704in the opposite direction of the shaft-center-direction reaction force Fc2to resist the shaft-center-direction reaction force Fc2(bending moment M).

Even if the moment causing the fall toward the side opposite to the movable sheave66is applied to the fixed sheave704due to the reaction force F applied from the transmission belt56, the parking gear602radially supports the inner circumferential surface of the annular fitting portion704aof the fixed sheave704with the annular projecting portion602bof the parking gear602on the falling side. The parking gear602of this embodiment functions as a radially supporting member resisting a radial reaction force Fr that is a component in the direction orthogonal to the shaft center C2of the reaction force F so as to prevent the fixed sheave704from falling.

The continuously variable transmission700of this embodiment includes the oil pressure chamber608made of a space surrounded in an oil-tight manner by the main body portion602aand the annular projecting portion602bof the parking gear604and the fixed sheave64to generate a hydraulic force pressing the wall surface of the fixed sheave704on the side opposite to the movable sheave66, i.e., the back surface706, toward the movable sheave66when the secondary oil pressure adjusted and controlled by the hydraulic control device is supplied. As a result, even if the shaft-center-direction reaction force Fc2in the direction of the shaft center C2is applied from the transmission belt56to the fixed sheave704by clamping the transmission belt56between the fixed sheave704and the movable sheave66, the pressing force is generated by the oil pressure chamber608formed with the parking gear602having only a relatively simple change from those conventionally used and the fixed sheave and acts on the back surface706of the fixed sheave704to resist the shaft-center-direction reaction force Fc2and, therefore, the fall of the fixed sheave704can be suppressed without adding a part with a relatively simple configuration.

In the continuously variable transmission700of this embodiment, since the annular projecting portion602bof the parking gear602is fitted into and radially engaged with the annular fitting portion704aprojected from the outer circumferential portion of the back surface706of the fixed sheave704toward the parking gear602, even if the moment causing the fall toward the side opposite to the movable sheave66is applied to the fixed sheave704due to the reaction force F applied from the transmission belt56, the annular projecting portion602bof the parking gear602radially supports the inner circumferential surface of the annular fitting portion704aof the fixed sheave704and, therefore, the fall of the fixed sheave704can be suppressed.

Although the exemplary embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to these embodiments and is also implemented in other forms.

For example, while the parking gear86(204,304,404,504, and602) is disposed on the output shaft50, the parking gear may be disposed on the input shaft34.

Although the pressing force from the parking gear86to the fixed sheave64is preliminarily applied to the fixed sheave64(206,306,406,506, and704) by clamping the parking gear86(204,304,404,504, and602) in the direction of the shaft center C2between the nut92and the fixed sheave64(206,306,406,506, and704), this pressing force may not necessarily be applied. If applied, the pressing force may not be a larger value as much as possible within a range in which the fixed sheave64is not deformed toward the movable sheave66.

Although, in the sixth and seventh embodiments, the parking gear602includes the O-ring606fitted into the O-ring groove604formed in the surface of the annular projecting portion602bfacing the back surface90and the oil pressure chamber608consists of an oil-tightly surrounded annular space formed in the inner circumferential side of the annular projecting portion602bby disposing the O-ring606in close contact with each of the bottom surface of the O-ring groove604and the back surface90, the oil pressure chamber608may be formed by disposing another seal member instead of the O-ring606. The oil pressure chamber608may be formed by jointing the annular projecting portion602bof the parking gear602and the back surface90of the fixed sheave64(704) by welding etc., continuously in a circumferential direction without a gap, for example.

Although, in the sixth and seventh embodiments, the parking gear602is abutted on the fixed sheave64(704) via the O-ring606, the annular projecting portion602bmay be abutted on the fixed sheave64(704). A pressing force from the parking gear602to the fixed sheave64(704) may preliminarily be applied by clamping the parking gear602in the direction of the shaft center C2between the nut92and the fixed sheave64(704).

The described embodiments are merely exemplary embodiments and, although not exemplarily illustrated one by one, the present invention may be implemented in variously modified and improved forms based on the knowledge of those skilled in the art without departing from the spirit thereof.

DESCRIPTION OF REFERENCE NUMERALS

18,200,300,400,500,600,700: belt type continuously variable transmission for a vehicle34: input shaft46: primary pulley (groove width variable pulley)50: output shaft (one of the input shaft and the output shaft)52,202,302,402,502,702: secondary pulley (groove width variable pulley)54: V-groove56: transmission belt64,206,306,406,506,704: fixed sheave66: movable sheave86,204,304,404,504,602: parking gear86a,204a,304a,404a,504a,602a: main body portion86b,204b,304b,404b,504b,602b: annular projecting portion304c: stopper portion90,208,308,408,508,706: back surface (wall surface of the fixed sheave on the side opposite to the movable sheave)92: nut410,510: first spline teeth (engagement teeth)608: oil pressure chamber