JP6374448B2 - Belt type continuously variable transmission - Google Patents

Description

  The present invention provides a drive pulley in which a movable pulley half, which is slidably fitted in the input shaft in an axially slidable manner with respect to a fixed pulley half fixed to the input shaft, and an output shaft, A driven pulley that can be slidably fitted to the output shaft in an axially slidable manner with respect to a fixed fixed pulley half, and a driven pulley that is capable of approaching and separating, and the drive pulley and the driven pulley are wound around A gear ratio can be changed by hydraulically changing the groove width of the drive pulley and the driven pulley, and the open position of the movable pulley half of the drive pulley at the LOW speed ratio. The present invention relates to a belt-type continuously variable transmission that can be controlled by a stopper.

  While the belt type continuously variable transmission is generating creep force, the gear ratio is shifted slightly from LOW to the OD side, and then the gear ratio is returned to LOW to start the vehicle, so that the noise during creep Japanese Patent Application Laid-Open No. H10-228707 discloses a method for ensuring a driving force necessary for starting while preventing vibration.

JP-A-8-177998

  However, in the above-mentioned conventional one, although noise and vibration while the vehicle is stopped are considered, the influence of the axial thrust of the drive pulley on the coefficient of friction between the drive pulley and the metal belt is not taken into account. When the converter generates a high stall torque, the drive pulley's shaft thrust is insufficient, causing a slip of the metal belt, resulting in reduced power transmission efficiency and noise, and the torque converter generates a low stall torque. On the other hand, when the vehicle is started, the drive pulley has an excessive axial thrust, which may lead to a decrease in the life of the metal belt and a decrease in power transmission efficiency.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to prevent slippage of a metal belt at the time of start of a vehicle, reduce axial thrust, improve the life of a metal belt, and improve power transmission efficiency.

To achieve the above object, according to the first aspect of the present invention, the movable side of the fixed side pulley half fixed to the input shaft is slidably fitted to the input shaft in the axial direction. A drive pulley that can move toward and away from the pulley half, and a movable pulley half that fits slidably in the axial direction to the output shaft with respect to the fixed pulley half fixed to the output shaft. A possible driven pulley, the drive pulley, and a metal belt wound around the driven pulley, the gear ratio can be changed by hydraulically changing the groove width of the drive pulley and the driven pulley, and a restriction can be belt-type continuously variable transmission by a stopper to open the open position of the movable pulley half of the drive pulley in the LOW gear ratio when the vehicle starts from a stopped state, slow onset of said vehicle If the stall torque is the accelerator pedal in order to input from the torque converter to the input shaft by being depressed slowly is less than the predetermined value, the reaction force against per the drive pulley stopper the axial thrust pressure and the opening of When the stall pedal input from the torque converter to the input shaft exceeds a predetermined value due to a sudden depression of the accelerator pedal to suddenly start the vehicle, the shaft thrust of the drive pulley is hydraulic only A belt type continuously variable transmission is proposed.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the magnitude of the stall torque is determined based on a stator reaction force of the torque converter. A machine is proposed.

  According to the invention described in claim 3, in addition to the configuration of claim 1 or 2, the gear ratio when the stall torque is greater than or equal to a predetermined value is the same as that when the stall torque is less than the predetermined value. A belt type continuously variable transmission is proposed that is shifted to the OD side with respect to the gear ratio.

  According to the invention described in claim 4, in addition to the structure of any one of claims 1 to 3, the opening stopper abuts on the outer peripheral portion of the movable pulley half of the drive pulley. A belt type continuously variable transmission is proposed.

  According to the invention described in claim 5, in addition to the structure of claim 4, the opening stopper is elastically movable in the axial direction by contact with the movable pulley half of the drive pulley. A belt type continuously variable transmission is proposed.

  According to a sixth aspect of the invention, in addition to the configuration of the fourth or fifth aspect, the drive pulley is slidably fitted into a cylinder fixed to the movable pulley half. A belt type continuously variable transmission is proposed in which the piston is provided in a piston that defines an oil chamber, and the piston is supported by the input shaft so as to be swingable and relatively rotatable.

  According to the configuration of the first aspect, when the vehicle starts, the stall torque input from the torque converter to the input shaft is less than a predetermined value, and the movable pulley half of the drive pulley and the contact of the opening stopper when the vehicle starts. When the decrease in the coefficient of friction between the drive pulley and the metal belt due to contact is small, the drive pulley's axial thrust is applied by the hydraulic pressure and the contact reaction force of the opening stopper, so the drive pulley acting on the movable pulley half from the stopper Even if the hydraulic pressure is reduced by the amount of the reaction force in the closing direction, the slip of the metal belt can be suppressed, and the driving efficiency of the belt type continuously variable transmission can be increased by reducing the required driving force of the hydraulic pump.

  In addition, the stall torque input to the input shaft from the torque converter is equal to or greater than a predetermined value, and the friction coefficient between the drive pulley and the metal belt is reduced by the contact of the movable pulley half of the drive pulley and the opening stopper when the vehicle starts. Is large, the drive pulley's axial thrust is applied only by hydraulic pressure, which not only prevents the friction coefficient from being reduced due to the reaction force from the opening stopper, but also acts on the movable pulley half from the opening stopper. The reaction force in the closing direction of the drive pulley does not affect the axial thrust of the drive pulley, and the drive pulley hydraulic pressure can be accurately set to a value that can transmit the necessary torque while suppressing the slip of the metal belt. It becomes possible. In addition, it is not necessary to increase the hydraulic pressure of the driven pulley to cancel the reaction force from the stopper and open the movable pulley half of the drive pulley to bias it to the stopper side. In addition, it is possible to prevent the transmission efficiency and durability of the belt type continuously variable transmission from being reduced due to excessive shaft thrust.

  According to the second aspect of the present invention, since the magnitude of the stall torque is determined based on the stator reaction force of the torque converter, the magnitude of the stall torque can be determined easily and with high accuracy.

  According to the third aspect of the present invention, the gear ratio when the stall torque at the start of the vehicle is greater than or equal to a predetermined value is shifted to the OD side from the gear ratio when the stall torque at the start of the vehicle is less than the predetermined value. As a result, the winding diameter of the metal belt around the drive pulley is increased by the amount the gear ratio deviates from LOW to OD, so that the friction coefficient is prevented from decreasing, and the drive pulley's axial thrust is not specifically increased. Thus, a smooth start can be achieved with a driving force equal to or greater than the LOW speed ratio.

  According to the fourth aspect of the present invention, since the opening stopper contacts the outer peripheral portion of the movable pulley half of the drive pulley, even if the flatness and position accuracy of the opening stopper are low, the movable pulley half Is suppressed in inclination at the fitting portion with respect to the input shaft. As a result, the deflection amount of the radially inner portion of the movable pulley half around which the metal belt is wound at the LOW speed ratio is suppressed, and the reduction in the friction coefficient between the drive pulley and the metal belt is suppressed.

  According to the fifth aspect of the present invention, the opening stopper can be elastically moved in the axial direction by contact with the movable pulley half of the drive pulley. It becomes more difficult to be affected by the positional accuracy, and the reduction in the friction coefficient between the drive pulley and the metal belt is more effectively suppressed.

  According to the sixth aspect of the present invention, the drive pulley is provided on the piston that slidably fits in the cylinder fixed to the movable pulley half and divides the oil chamber, and the piston swings around the input shaft. Since it is supported in such a manner, the movable pulley half is not affected by the flatness and position accuracy of the opening stopper provided on the piston, and the reduction of the friction coefficient is further effectively suppressed. In addition, since the piston can be rotated relative to the movable pulley half that rotates integrally with the input shaft while having a predetermined sliding resistance, the change in the rotational angular velocity of the input shaft due to the rotational fluctuation of the engine is reduced. In addition, oil leakage from the oil chamber can be prevented by keeping the positional relationship between the cylinder and the piston constant.

The figure which shows the structure of a belt-type continuously variable transmission. (First embodiment) The flowchart of the axial thrust control at the time of start. (First embodiment) The time chart of the axial thrust control at the time of start. (First embodiment) The schematic diagram of a drive pulley. (First embodiment) The graph which shows the relationship of the friction coefficient (transmission efficiency) with respect to a gear ratio. (First embodiment) The schematic diagram of a drive pulley. (Second to fourth embodiments)

First embodiment

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a belt-type continuously variable transmission that continuously transmits a rotation of an input shaft 11 connected to an engine to an output shaft 12 connected to driving wheels is provided on the input shaft 11. The metal belt 15 is wound around the drive pulley 13 and the driven pulley 14 provided on the output shaft 12. The belt-type continuously variable transmission shown in FIG. 1 is in a state where the vehicle starts, that is, in a LOW state where the speed ratio is maximum.

  The drive pulley 13 includes a fixed pulley half 16 fixed to the input shaft 11 and a movable side in which a boss portion 17a is supported on the input shaft 11 via a sliding key 18 so as to be axially slidable and relatively non-rotatable. The movable pulley half 17 can be moved toward and away from the fixed pulley half 16. A piston 19 fixed to the input shaft 11 is slidably fitted to a cylinder 20 formed integrally with the movable pulley half 17, and between the piston 19, the cylinder 20 and the movable pulley half 17. An oil chamber 21 is defined.

  The driven pulley 14 includes a fixed pulley half 22 fixed to the output shaft 12 and a movable side in which the boss portion 23a is supported on the output shaft 12 through a sliding key 24 so as to be slidable in the axial direction and not relatively rotatable. The movable pulley half 23 can be moved toward and away from the fixed pulley half 22. A piston 25 fixed to the output shaft 12 is slidably fitted to a cylinder 26 formed integrally with the movable pulley half 17, and between the piston 25, the cylinder 26 and the movable pulley half 23. An oil chamber 27 is defined.

  Accordingly, when the hydraulic pressure applied to the oil chamber 21 of the drive pulley 13 is decreased and the hydraulic pressure applied to the oil chamber 27 of the driven pulley 14 is increased, the movable pulley half 17 of the drive pulley 13 is separated from the fixed pulley half 16. Thus, the groove width increases, the movable pulley half 23 of the driven pulley 14 approaches the fixed pulley half 22, the groove width decreases, and the winding diameter of the metal belt 15 around the drive pulley 13 decreases. As the winding diameter of the metal belt 15 around the driven pulley 14 increases, the gear ratio increases toward LOW.

  Conversely, when the hydraulic pressure applied to the oil chamber 21 of the drive pulley 13 is increased and the hydraulic pressure applied to the oil chamber 27 of the driven pulley 14 is decreased, the movable pulley half 17 of the drive pulley 13 becomes the fixed pulley half 16. The groove width is reduced by approaching, and the stationary pulley half 22 is separated from the movable pulley half 23 of the driven pulley 14 to increase the groove width, and the winding diameter of the metal belt 15 around the drive pulley 13 is increased. As a result, the winding diameter of the metal belt 15 with respect to the driven pulley 14 is reduced, so that the gear ratio is reduced toward OD (overdrive).

  When the gear ratio changes toward LOW, the movable pulley half 17 of the drive pulley 13 moves away from the fixed pulley half 16, and when the gear ratio reaches LOW, the boss portion 17a of the movable pulley half 17 in the figure. The left end comes into contact with the opening stopper 19a at the base of the piston 19, and further movement of the movable pulley half 17 is restricted.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

In the present embodiment, based on the magnitude of the stall torque input from the torque converter to the input shaft 11 of the belt type continuously variable transmission when the vehicle starts, the pulley side pressure of the drive pulley 1 3 Contact and the driven pulley 14 is It is controlled in different ways. The stall torque is torque that is output from the torque converter and input to the input shaft 11 of the continuously variable transmission when the turbine of the torque converter is stopped, that is, when the vehicle is in a stopped state.

In the flowchart of FIG. 2 showing the control at the start of the vehicle, first, in step S1, the hydraulic pressure of the drive pulley 13 is set to the initial value, that is, the normal hydraulic pressure applied in the general slip prevention control of the conventional belt type continuously variable transmission, for example. Set to 80%. In this state, the hydraulic pressure applied to the driven pulley 14 is superior to the hydraulic pressure applied to the drive pulley 13, and the load that closes the driven pulley 14 is transmitted to the drive pulley 13 via the metal belt 15, thereby opening the drive pulley 13. As a result, the movable pulley half 17 is separated from the fixed pulley half 16, the boss portion 17a of the movable pulley half 17 is abutted against the stopper 19a, and the gear ratio becomes LOW.

  In the following step S2, the stator reaction force of the torque converter when the driver depresses the accelerator pedal to start the vehicle is referred. The stator reaction force when the vehicle starts is correlated with the stall torque, which is the output torque of the torque converter when the vehicle starts, and the magnitude of the stall torque can be easily and accurately determined based on the stator reaction force. it can. If the stator reaction force is equal to or greater than the threshold value, it is determined that the driver is depressing the accelerator pedal and the high stall torque starts, and the process proceeds to step S3. If the stator reaction force is less than the threshold value, the driver It is determined that the low stall torque is started by slowly depressing the accelerator pedal, and the process proceeds to step S6.

If it is determined in step S2 that the high stall torque has been started, the hydraulic pressure of the drive pulley is increased from 80% to 100% of the normal hydraulic pressure in step S3, and the movable pulley half 17 is changed to the fixed pulley half 16 . is moved toward, is separated from the stopper 19a opens the boss portion 17a of the movable pulley half 17. Thus, when the gear ratio is slightly changed from LOW to the OD side, the vehicle is started in this state (high stall torque start).

  Then, after the start in step S4, when the driver once loosens the accelerator pedal and the stator reaction force becomes less than the threshold value, the drive pulley hydraulic pressure is reduced from 100% of the normal hydraulic pressure to the abutting reference hydraulic pressure (for example, 50% of the normal hydraulic pressure). By moving the movable pulley half 17 closer to the fixed pulley half 16, the boss 17a of the movable pulley half 17 is brought into contact with the stopper 19a, and the transmission ratio is set to LOW. In the subsequent step S5, the gear ratio is changed from LOW to OD by gradually increasing the hydraulic pressure of the driven pulley 14 from the abutting reference hydraulic pressure in accordance with the acceleration of the vehicle.

  On the other hand, if it is determined in step S2 that the low stall torque is started, in step S6, the hydraulic pressure of the drive pulley is reduced from 80% of the normal hydraulic pressure to 50% of the normal hydraulic pressure that is the abutting reference hydraulic pressure. The boss portion 17a of the half body 17 is opened and brought into contact with the stopper 19a, and the vehicle is started with the gear ratio being LOW (low stall torque start). In step S7, the gear ratio is changed from LOW to OD by gradually increasing the hydraulic pressure of the driven pulley 14 from the abutting reference hydraulic pressure in accordance with the acceleration of the vehicle.

  A specific example of the above action will be further described based on the time chart of FIG. In FIG. 3, the solid line indicates the characteristic of high stall torque start, and the broken line indicates the characteristic of low stall torque start.

  When the driver depresses the accelerator pedal strongly in order to start the vehicle suddenly, it is determined that the stator reaction force exceeds the threshold value and the high stall torque starts, and the hydraulic pressure of the drive pulley 13 increases and the gear ratio is slightly lower than LOW. The boss portion 17a of the movable pulley half 17 is controlled to the OD side, and the float control for starting the high stall torque is performed in which the boss portion 17a is separated from the stopper 19a and floats. Thereafter, when the driver loosens the accelerator pedal once and the stator reaction force becomes less than the threshold value, the hydraulic pressure of the drive pulley 13 is reduced and the transmission ratio is returned to LOW, and the boss portion 17a of the movable pulley half 17 is opened and stopped. The process shifts to the abutment control of the high stall torque start that comes into contact with 19a and enters a restrained state. Thereafter, when the driver gradually depresses the accelerator pedal to accelerate the vehicle, the hydraulic pressure of the drive pulley 13 increases and the gear ratio changes from LOW to OD.

  On the other hand, when the driver slowly depresses the accelerator pedal to start the vehicle slowly, it is determined that the stator reaction force is maintained below the threshold value and the low stall torque is started, and the hydraulic pressure of the drive pulley 13 decreases and the movable side is reduced. The low stall torque start is executed at a LOW speed ratio where the boss portion 17a of the pulley half 17 contacts the stopper 19a. Thereafter, when the driver gradually depresses the accelerator pedal to accelerate the vehicle, the hydraulic pressure of the drive pulley 13 increases and the gear ratio changes from LOW to OD.

  Next, the effect of the pulley thrust control described above will be described.

  FIG. 4A schematically shows a state in which the boss portion 17a of the movable pulley half 17 of the drive pulley 13 is not in contact with the opening stopper 19a and the gear ratio is slightly shifted from LOW to the OD side. Yes. When the drive pulley 13 clamps the metal belt 15 with the axial thrust, the metal belt 15 contacts only a part of the V surface of the drive pulley 13, so that the movable pulley half 17 is fixed to the fixed pulley by the reaction force of the axial thrust. The movable pulley half 17 is inclined with respect to the axis of the input shaft 11 by receiving the moment indicated by the arrow M with respect to the half 16.

  At this time, since the inner diameter of the boss portion 17a of the movable pulley half 17 is slightly larger than the outer diameter of the input shaft 11, both ends in the diameter direction of the boss portion 17a are in contact with the outer periphery of the input shaft 11. Thus, the inclination angle θ of the movable pulley half 17 is regulated. Since the boss 17a and the input shaft 11 of the movable pulley half 17 are highly rigid and have high processing accuracy, the inclination angle θ is maintained substantially constant during the rotation of the movable pulley half 17. Therefore, the movable pulley half 17 rotates within the same plane of rotation without swinging (raising motion), and as a result, the fixed pulley half 16 and the movable pulley half 17 are rotated while the drive pulley 13 is rotating. The groove width does not change, and the friction coefficient between the metal belt 15 and the V plane of the drive pulley 13 hardly decreases.

  FIG. 4B schematically shows a state in which the boss portion 17a of the movable pulley half 17 of the drive pulley 13 is in contact with the opening stopper 19a and the gear ratio matches LOW. When one end portion of the boss portion 17a of the movable pulley half body 17 is in contact with the opening stopper 19a, the inclination angle θ of the movable pulley half body 17 is regulated by the contact between the both end portions of the boss portion 17a and the input shaft 11. The posture of the movable pulley half 17 is restricted by the contact between one end of the boss 17a and the opening stopper 19a. However, since the opening stopper 19a formed by the base of the plate-shaped piston 19 that defines the oil chamber 21 has a relatively low rigidity, the movable pulley half 17 swings around as the piston 19 deforms. As a result, the groove widths of the stationary pulley half 16 and the movable pulley half 17 vary during the rotation of the drive pulley 13, and there is a problem that the friction coefficient between the metal belt 15 and the V plane of the drive pulley 13 decreases.

  FIG. 4C also schematically shows a state where the boss portion 17a of the movable pulley half 17 of the drive pulley 13 is in contact with the opening stopper 19a and the gear ratio is matched to LOW. When the rigidity of the piston 19 is high and the opening stopper 19a is kept at a right angle to the axis of the input shaft 11, the movable pulley half 17 is pulled in the direction perpendicular to the axis by the tension of the metal belt 15, The boss portion 17a is pressed against the opening stopper 19a and fixed in a state where the boss portion 17a is radially displaced from the axis of the input shaft 11 by a distance δ corresponding to the gap between the boss portion 17a and the input shaft 11. May end up. Also in this case, since the movable pulley half 17 swings in an eccentric state with respect to the fixed pulley half 16 at the portion where the metal belt 15 is wound, the fixed pulley half 16 and the movable pulley half 17 There is a problem that the groove width fluctuates and the friction coefficient between the metal belt 15 and the V plane of the drive pulley 13 decreases.

  As described above, when the boss portion 17a of the drive pulley 13 opens and contacts the stopper 19a at the LOW speed ratio, there is a problem that the movable pulley half 17 swings and the friction coefficient decreases. Since the torque input to the input shaft 11 is large, the more the axial thrust of the drive pulley 13 is, the more prominent.

  In the present embodiment, when the high stall torque starts when the friction coefficient decreases significantly due to the contact between the movable pulley half 17 of the drive pulley 13 and the opening stopper 19a, the gear ratio is slightly shifted from LOW to the OD side. Since the contact between the movable pulley half 17 and the opening stopper 19a is avoided by shifting to the position, the friction coefficient between the drive pulley 13 and the metal belt 15 due to the reaction force from the opening stopper 19a is prevented. In addition, the reaction force from the opening stopper 19a does not affect the axial thrust of the drive pulley 13, and the hydraulic pressure of the drive pulley 13 is set to a value that can transmit the necessary torque while suppressing the slip of the metal belt 15. It becomes possible to set accurately. Further, since the contact between the movable pulley half 17 and the opening stopper 19a is avoided, the hydraulic pressure applied to the oil chamber 27 of the driven pulley 14 is increased in order to cancel the reaction force from the opening stopper 19a. Since it is no longer necessary to open the movable pulley half 17 to urge the stopper 19a, not only can the required hydraulic pressure be reduced, but also the transmission efficiency and durability of the belt-type continuously variable transmission due to excessive axial thrust can be reduced. The fall of property can be prevented.

  Further, when the low stall torque is started with a small decrease in the friction coefficient due to the contact between the movable pulley half 17 of the drive pulley 13 and the opening stopper 19a, the gear ratio is set to LOW and the movable pulley half 17 is opened. Since the stopper 19a is brought into contact, even if the hydraulic pressure of the drive pulley 13 is reduced by the reaction force in the closing direction of the drive pulley 13 that acts on the movable pulley half 17 from the opening stopper 19a, the metal belt 15 is prevented from slipping. This can be suppressed, and the driving efficiency of the belt-type continuously variable transmission can be increased by reducing the required driving force of the hydraulic pump.

  FIG. 5 is a graph showing how the friction coefficient μ between the drive pulley 13 and the metal belt 15 or the transmission efficiency η of the continuously variable transmission changes with respect to the transmission ratio of the continuously variable transmission. is there. The transmission efficiency η depends on the friction coefficient μ, and the change characteristics of the friction coefficient μ and the transmission efficiency η are the same. The friction coefficient μ and the transmission efficiency η at the start of the high stall torque indicated by the solid line are lower than the friction coefficient μ and the transmission efficiency η at the start of the low stall torque indicated by the broken line, and the difference between them is particularly close to the LOW gear ratio. It has become prominent.

In the present embodiment, the high stall torque is started at a gear ratio = 2.3 slightly shifted to the OD side from the gear ratio = 2.5 (LOW), but it is temporarily high at a gear ratio = 2.5 (LOW). A case where the stall torque starts is considered as a comparative example. In this comparative example, assuming that the transmission efficiency η when the gear ratio = 2.5 (LOW) is η2.5 and the input torque to the continuously variable transmission is Tin, the output torque Tout2 of the continuously variable transmission in this case .5 is
Tout2.5 = Tin × η2.5 × 2.5
Given in.

On the other hand, in this embodiment, assuming that the transmission efficiency η when the gear ratio = 2.3 is η2.3 and the input torque to the continuously variable transmission is Tin, the output torque Tout2 of the continuously variable transmission in this case .3
Tout2.3 = Tin × η2.3 × 2.3
Given in.

  Therefore, Tout2.3> Tout2.5 can be achieved by setting the gear ratio at the time of high stall torque start so that η2.5 / η2.3 <2.3 / 2.5 is established. As described above, when the gear ratio is shifted from LOW to OD when the high stall torque starts, the winding diameter of the metal belt 15 around the drive pulley 13 is increased to suppress the reduction of the friction coefficient, and the axial thrust of the drive pulley 13 is reduced. Without special increase, it is possible to start smoothly with a driving force equal to or higher than the LOW speed ratio.

Second to fourth embodiments

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, one end of the boss 17a of the movable pulley half 17 is brought into contact with the opening stopper 19a formed by the base of the piston 19 to establish the LOW speed ratio. In this embodiment, the outer peripheral portion of the movable pulley half 17 is brought into contact with the opening stopper 19a formed by the outer peripheral portion of the piston 19 to establish the LOW speed ratio. According to the second embodiment, the boss portion 17a of the movable pulley half 17 and the base portion of the relatively high-rigidity piston 19 do not come into contact with each other, and compared with the outer peripheral portion of the movable pulley half 17. Since the outer peripheral portion of the low-rigidity piston 19 comes into contact with each other, the boss portion 17a can come into contact with the input shaft 11 at both axial end portions, and the swinging of the movable pulley half body 17 is suppressed. Thus, a decrease in the friction coefficient in the LOW speed ratio is suppressed. As a result, when the low stall torque starts, it is possible to minimize a decrease in the friction coefficient due to the movable pulley half 17 being in contact with the opening stopper 19a.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  The third embodiment is an improvement over the second embodiment, in which the piston 19 is made thin so that it can be elastically deformed. As a result, even when the movable pulley half 17 is in contact with the opening stopper 19a, the piston 19 itself is elastically deformed so that the movable pulley half 17 is at a constant inclination angle θ with respect to the input shaft 11. By tilting and the boss portion 17a abutting against the input shaft 11 at two points on both ends in the axial direction, it is possible to prevent the movable pulley half 17 from swinging and to more effectively suppress the decrease in the friction coefficient. .

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  The fourth embodiment is also an improvement of the second embodiment. By supporting the base portion of the piston 19 on the input shaft 11 via the spherical bearing 28, the fourth embodiment can swing with respect to the input shaft 11 and can be input. It is supported so as to be rotatable relative to the shaft 11. As a result, the movable pulley half 17 is not affected by the flatness and position accuracy of the opening stopper 19a of the piston 19 and the reduction of the friction coefficient is more effectively suppressed. Can be rotated relative to the movable pulley half 17 that rotates integrally with the movable pulley half 17 with a predetermined sliding resistance, so that the change in the rotational angular velocity of the input shaft 11 due to the engine rotational fluctuation can be reduced. In addition, the positional relationship between the cylinder 20 and the piston 19 can be kept constant and oil leakage from the oil chamber 21 can be prevented.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the gear ratio at the time of starting the high stall torque and the gear ratio at the time of starting the low stall torque are not limited to the embodiment.

11 Input shaft 12 Output shaft 13 Drive pulley 14 Driven pulley 15 Metal belt 16 Drive pulley fixed pulley half 17 Drive pulley movable pulley half 19 Piston 19a Opening stopper 20 Cylinder 21 Oil chamber 22 Driven pulley fixed pulley Half 23 Driven pulley movable side pulley half

Claims (6)

A movable pulley half (17) that is slidably fitted in the input shaft (11) in an axially slidable manner can move toward and away from a fixed pulley half (16) fixed to the input shaft (11). Drive pulley (13) and a movable pulley half that is slidably fitted to the output shaft (12) in an axial direction with respect to a fixed pulley half (22) fixed to the output shaft (12) (23) comprises a driven pulley (14) capable of approaching and separating, and the drive pulley (13) and a metal belt (15) wound around the driven pulley (14), the drive pulley (13) and The gear ratio can be changed by hydraulically changing the groove width of the driven pulley (14), and the open position of the movable pulley half (23) of the drive pulley (13) is opened at the LOW gear ratio. (19a) A Ri regulation can be a belt-type continuously variable transmission,
When the stall torque input from the torque converter to the input shaft (11) is less than a predetermined value by slowly depressing the accelerator pedal to start the vehicle slowly when starting the vehicle from the stop state , The shaft thrust of the drive pulley (13) is given by the hydraulic pressure and the reaction force applied by the opening stopper (19a), and the accelerator pedal is suddenly depressed to suddenly start the vehicle, so that the input shaft ( 11) A belt type continuously variable transmission in which the axial thrust of the drive pulley (13) is applied only by hydraulic pressure when the stall torque input to 11) is a predetermined value or more.   The belt type continuously variable transmission according to claim 1, wherein the magnitude of the stall torque is determined based on a stator reaction force of the torque converter.   The transmission ratio when the stall torque at the start of the vehicle is greater than or equal to a predetermined value is shifted to the OD side from the transmission ratio when the stall torque at the start of the vehicle is less than a predetermined value. The belt-type continuously variable transmission according to claim 1 or 2.   The belt according to any one of claims 1 to 3, wherein the opening stopper (19a) is in contact with an outer peripheral portion of a movable pulley half (17) of the drive pulley (13). Type continuously variable transmission.   The belt according to claim 4, wherein the opening stopper (19a) is elastically movable in the axial direction by contact with the movable pulley half (17) of the drive pulley (13). Type continuously variable transmission.   The drive pulley (13) is provided in a piston (19) that slidably fits in a cylinder (20) fixed to the movable pulley half (17) to partition an oil chamber (21), The belt-type continuously variable transmission according to claim 4 or 5, wherein the piston (19) is supported by the input shaft (11) so as to be swingable and relatively rotatable.

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