JP2022001779A - Control device - Google Patents

Abstract

To provide a control device which can improve the responsiveness of switching to a first mode from a second mode.SOLUTION: In gear change control, a target gear change ratio being a target of a total gear change ratio is set, and a belt gear change ratio is changed so that the total gear change ratio coincides with the target gear change ratio. In a split mode, when the target gear change ratio which is equal to or higher than a switching value is set, switching to a belt mode from the split mode is determined. When the belt gear change ratio is changed to a value smaller than a standby threshold from a value equal to or larger than the standby threshold which is larger than the switching value before the switching determination, engagement-side control pressure being a target value of hydraulic pressure supplied to an engagement-side clutch is set to the standby pressure via filling pressure, and the engagement-side clutch is thereby brought into a state that the standby pressure equal to or lower than the hydraulic pressure at which the clutch begins to possess transmission torque acts thereon.SELECTED DRAWING: Figure 7

Description

The present invention relates to a control device for controlling a continuously variable transmission.

As a transmission mounted on a vehicle such as an automobile, it is equipped with a continuously variable transmission mechanism that shifts power steplessly, and power division that can divide and transmit power between an input shaft and an output shaft in two paths. A type of continuously variable transmission has been proposed.

In an example of a continuously variable transmission of a power split type, the continuously variable transmission has a configuration similar to that of a known belt-type continuously variable transmission (CVT), that is, an endless belt on a primary pulley and a secondary pulley. Has a wound structure. The engine power input to the input shaft is transmitted to the primary shaft of the continuously variable transmission mechanism. The secondary shaft of the continuously variable transmission mechanism is connected to the sun gear of the planetary gear mechanism.

Further, the power split type continuously variable transmission is provided with a parallel shaft type gear mechanism. The parallel shaft gear mechanism includes a split drive gear in which the power of the input shaft is transmitted / cut off, and a split driven gear that constitutes a gear train with the split drive gear and rotates integrally with the carrier of the planetary gear mechanism. An output shaft is connected to the ring gear of the planetary gear mechanism. The rotation of the output shaft is transmitted to the differential gear, and is transmitted from the differential gear to the left and right drive wheels.

A belt mode and a split mode are provided as the power transmission mode during forward traveling.

In the belt mode, the first clutch that switches the transmission / disconnection of power between the input shaft and the split drive gear is released, the split drive gear is put into a free rotation state, and the carrier of the planetary gear mechanism is in a free rotation state. Will be done. Further, the second clutch that engages / separates the sun gear and the ring gear of the planetary gear mechanism is engaged, and the sun gear and the ring gear are coupled. Therefore, the power output from the continuously variable transmission mechanism causes the sun gear and the ring gear to rotate integrally, and the output shaft rotates integrally with the ring gear. Therefore, in the belt mode, the larger the belt gear ratio (pulley ratio), which is the gear ratio of the continuously variable transmission mechanism, the more the total gear ratio, which is the gear ratio of the entire power split type continuously variable transmission, in proportion to the gear ratio. The ratio (the number of rotations of the input shaft / the number of rotations of the output shaft) becomes large.

In the split mode, the second clutch is released and the coupling between the sun gear and the ring gear of the planetary gear mechanism is released. Further, the first clutch is engaged and power is transmitted from the input shaft to the split drive gear. The power transmitted from the input shaft to the split drive gear is changed at a constant gear ratio (split point) from the split drive gear via the split driven gear, and is input to the carrier of the planetary gear mechanism. The sun gear rotates at a rotation speed according to the belt gear ratio. Therefore, in the split mode, the larger the belt gear ratio, the smaller the total gear ratio, and the total gear ratio below the split point can be realized.

Japanese Unexamined Patent Publication No. 2016-142302

In shift control in a power-split continuously variable transmission, for example, the accelerator opening (ratio of the operation amount to the maximum operation amount of the accelerator pedal) and the target rotation speed according to the vehicle speed are set according to the shift line diagram, and the stepless transmission is performed. A gear ratio that matches the rotation speed input to the transmission with the target rotation speed is set as the target gear ratio. Then, the belt gear ratio is changed so that the total gear ratio matches the target gear ratio.

Switching between the belt mode and the split mode is determined by comparing the target gear ratio and the gear ratio at the split point (split gear ratio). That is, in the belt mode, if the target gear ratio is equal to or less than the split gear ratio (Hi side), the switching from the belt mode to the split mode is determined. Further, in the split mode, if the target gear ratio is equal to or higher than the split gear ratio (Lo side), the switching from the split mode to the belt mode is determined.

FIG. 8 is a diagram showing a time change of the execution state of the switching control, the release side control pressure, and the engagement side control pressure at the time of switching from the split mode to the belt mode.

When the switching from the split mode to the belt mode is determined, the release control (switching control) for releasing the first clutch on the release side is started (time T11). In the release control, the release side control pressure, which is the target value of the hydraulic pressure supplied to the first clutch, is gradually reduced from the engagement pressure to 0 (period T11-T15).

Further, when the switching from the split mode to the belt mode is determined, the engagement control (switching control) for engaging the second clutch on the engaging side is started at the same time as the release control is started (time T11). ). In the engagement control, the engagement side control pressure, which is the target value of the hydraulic pressure supplied to the second clutch, is raised from 0 to a filling pressure close to the engagement pressure, and the engagement side is used for a predetermined period (period T11-T12). The control pressure is held at the filling pressure. While the engagement side control pressure is held at the filling pressure, the oil chamber of the second clutch and the oil passage connected to the oil chamber are filled with oil. After a predetermined period of time, the engagement side control pressure is lowered from the filling pressure to the initial pressure (time T12) until the piston of the second clutch is hydraulically pushed and the invalid stroke of the piston is eliminated (piston). Is held at the initial pressure (period T12-T13) until it abuts on the clutch plate. When the invalid stroke of the piston is eliminated, the engagement side control pressure is gradually increased from the initial pressure to the engagement pressure (period T13-T14).

While the engagement side control pressure is gradually increased from the initial pressure to the engagement pressure, the second clutch is engaged and the switching from the split mode to the belt mode is completed. Therefore, when the accelerator pedal is depressed and the target gear ratio is set to a value equal to or higher than the split gear ratio, it takes time from the determination of switching from split mode to belt mode to the completion of the switching. ..

An object of the present invention is to provide a control device capable of improving the responsiveness of switching from a second mode (split mode) to a first mode (belt mode).

In order to achieve the above object, the control device according to the present invention is a first engaging element that is interposed on a first power transmission path between an input shaft and an output shaft and is hydraulically engaged / disengaged. And a second engaging element that is interposed in the second power transmission path between the input shaft and the output shaft and engaged / disengaged by hydraulic pressure, and a belt transmission mechanism is provided on the second power transmission path. By releasing the first engaging element and engaging the second engaging element, the larger the belt gear ratio by the belt shifting mechanism, the larger the total gear ratio between the input shaft and the output shaft. When the mode is set, the second mode is set in which the total gear ratio becomes smaller as the belt gear ratio is larger due to the engagement of the first engaging element and the release of the second engaging element, and when the belt gear ratio is a constant switching value. , A control device that controls a stepless transmission configured so that the total gear ratio does not change even when the first mode and the second mode are switched, and sets the target gear ratio, which is the target of the total gear ratio. The target gear ratio setting means, the belt gear ratio changing means for changing the belt gear ratio so that the total gear ratio matches the target gear ratio set by the target gear ratio setting means, and the target gear ratio in the first mode. If the target gear ratio set by the setting means is equal to or less than the switching value, the switching from the first mode to the second mode is determined, and in the second mode, the target gear ratio set by the target gear ratio setting means is the switching value. If the above is the case, the belt is used for the switching determination means for determining the switching from the second mode to the first mode and the belt before the switching determination means determines the switching from the second mode to the first mode in the second mode. When the gear ratio changes from a standby threshold value greater than the switching value to a standby threshold value or less, hydraulic pressure is supplied to the second engaging element, and the second engaging element begins to have a transmission torque capacity. A state in which the standby pressure acts on the second engaging element, and the engagement waiting means for making the second engaging element stand by in the state is included.

According to this configuration, in the stepless transmission, the first engaging element is interposed on the first power transmission path between the input shaft and the output shaft, and the second is between the input shaft and the output shaft. A second engaging element is interposed on the power transmission path. By releasing the first engaging element and engaging the second engaging element, the continuously variable transmission becomes the first mode. In this first mode, the larger the belt gear ratio by the belt transmission mechanism, the more the input shaft and the output. The total gear ratio with the shaft increases. On the other hand, the engagement of the first engaging element and the release of the second engaging element put the continuously variable transmission into the second mode. In this second mode, the larger the belt gear ratio, the smaller the total gear ratio. When the belt gear ratio is a constant switching value, the total gear ratio does not change even if the first mode and the second mode are switched.

In the shift control, the target gear ratio, which is the target of the total gear ratio, is set, and the belt gear ratio is changed so that the total gear ratio matches the target gear ratio. When a target gear ratio equal to or less than the switching value is set in the first mode, switching from the first mode to the second mode is determined. When a target gear ratio equal to or higher than the switching value is set in the second mode, switching from the second mode to the first mode is determined.

In the second mode, before the switching from the second mode to the first mode is determined, the belt gear ratio changes from the standby threshold value larger than the switching value to less than the standby threshold value, and the second engagement is performed. Hydraulic pressure is supplied to the element, and the second engaging element is in a state in which a standby pressure equal to or lower than the hydraulic pressure that starts to have a transmission torque capacity is applied.

If the second engaging element is kept on standby in this state, the hydraulic pressure supplied to the second engaging element is increased in response to the determination of switching from the second mode to the first mode. 2 The engaging elements can be quickly engaged to complete the switch from the second mode to the first mode. Therefore, the time required from the determination of the switching from the second mode to the first mode to the completion of the switching can be shortened as compared with the conventional case. As a result, it is possible to improve the responsiveness of switching from the second mode to the first mode to the depression of the accelerator pedal (increasing the amount of operation of the accelerator operation), and by extension, the responsiveness of the acceleration of the vehicle can be improved. can.

The second engaging element is provided so that the plate and the disc face each other, and the hydraulic pressure supplied to the oil chamber causes the piston to move against the elastic force of the return spring, and the piston presses the plate against the disc. It may be a frictional engagement element that engages. In this case, the standby pressure may be set to a hydraulic pressure that applies a force equal to or less than the elastic force of the return spring in a state where the piston has moved to a position where it abuts on the plate.

Thereby, the standby pressure can be set to a hydraulic pressure equal to or lower than the hydraulic pressure at which the second engaging element starts to have the transmission torque capacity.

According to the present invention, the responsiveness of switching from the second mode to the first mode can be improved.

It is a skeleton diagram which shows the structure of the drive system of the vehicle which mounts the control device which concerns on one Embodiment of this invention. It is a figure which shows the state of a clutch and a brake at the time of moving forward and moving backward of a vehicle. It is a collinear diagram which shows the relationship of the rotation speed (rotational speed) of a sun gear, a carrier and a ring gear of a planetary gear mechanism. It is a figure which shows the relationship between the belt gear ratio by a belt transmission mechanism, and the total gear ratio of the whole transmission. It is a block diagram which shows the structure of the control system of a vehicle. It is sectional drawing which shows the structure of a clutch. It is a figure which shows the execution state of the switching control, the time change of the release side control pressure, and the engagement side control pressure at the time of switching from a split mode to a belt mode. It is a figure which shows the time change of the execution state, the release side control pressure and the engagement side control pressure in the conventional switching control.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Vehicle drive system>
FIG. 1 is a skeleton diagram showing the configuration of the drive system of the vehicle 1.

The vehicle 1 is an automobile whose drive source is the engine 2.

The engine 2 is provided with an electronic throttle valve for adjusting the amount of intake air into the combustion chamber of the engine 2, an injector (fuel injection device) that injects fuel into the intake air, and a spark plug that causes an electric discharge in the combustion chamber. Has been done. Further, the engine 2 is provided with a starter for starting the engine 2. The power of the engine 2 is transmitted to the differential gear 5 via the torque converter 3 and the continuously variable transmission 4, and is transmitted from the differential gear 5 to the left and right drive wheels 7L and 7R via the left and right drive shafts 6L and 6R, respectively. Will be done.

The engine 2 includes an E / G output shaft 11. The E / G output shaft 11 is rotated by the power generated by the engine 2.

The torque converter 3 includes a front cover 21, a pump impeller 22, a turbine runner 23, and a lockup mechanism 24. The E / G output shaft 11 is connected to the front cover 21, and the front cover 21 rotates integrally with the E / G output shaft 11. The pump impeller 22 is arranged on the side opposite to the engine 2 side with respect to the front cover 21. The pump impeller 22 is provided so as to be rotatable integrally with the front cover 21. The turbine runner 23 is arranged between the front cover 21 and the pump impeller 22 and is rotatably provided about a rotation axis common to the front cover 21.

The lockup mechanism 24 includes a lockup piston 25. The lockup piston 25 is provided between the front cover 21 and the turbine runner 23. The lockup mechanism 24 is provided by the differential pressure between the hydraulic pressure of the release oil chamber 26 between the lockup piston 25 and the front cover 21 and the hydraulic pressure of the engagement oil chamber 27 between the lockup piston 25 and the pump impeller 22. Lock-up is turned on (engaged) / off (released). That is, when the hydraulic pressure of the release oil chamber 26 is higher than the hydraulic pressure of the engaging oil chamber 27, the lockup piston 25 is separated from the front cover 21 due to the differential pressure, and the lockup is turned off. When the hydraulic pressure of the engaging oil chamber 27 is higher than the hydraulic pressure of the release oil chamber 26, the lockup piston 25 is pressed against the front cover 21 by the differential pressure to lock up on.

In the lock-up-off state, when the E / G output shaft 11 is rotated, the pump impeller 22 rotates. When the pump impeller 22 rotates, an oil flow from the pump impeller 22 to the turbine runner 23 is generated. This flow of oil is received by the turbine runner 23, and the turbine runner 23 rotates. At this time, the amplification action of the torque converter 3 occurs, and a torque larger than the torque of the E / G output shaft 11 is generated in the turbine runner 23.

In the lockup-on state, when the E / G output shaft 11 is rotated, the E / G output shaft 11, the pump impeller 22 and the turbine runner 23 rotate together.

The stepless transmission 4 includes an input shaft 31 and an output shaft 32, and is configured to be able to branch the power input to the input shaft 31 into two paths and transmit the power to the output shaft 32, that is, a so-called power split type. (Torque split type) It is a transmission. In order to form two power transmission paths, the continuously variable transmission 4 includes a belt transmission mechanism 33, a front reduction gear mechanism 34, a planetary gear mechanism 35, and a split transmission mechanism 36.

The input shaft 31 is connected to the turbine runner 23 of the torque converter 3 and is provided so as to be integrally rotatable around the same rotation axis as the turbine runner 23.

The output shaft 32 is provided in parallel with the input shaft 31. An output gear 37 is supported on the output shaft 32 so as to be relatively non-rotatable. The output gear 37 meshes with the differential gear 5 (the ring gear of the differential gear 5).

The belt transmission mechanism 33 has the same configuration as a known belt-type continuously variable transmission (CVT). Specifically, the belt transmission mechanism 33 includes a primary shaft 41, a secondary shaft 42 provided in parallel with the primary shaft 41, a primary pulley 43 non-rotatably supported by the primary shaft 41, and a secondary shaft 42. It includes a secondary pulley 44 that is supported so as not to rotate relative to each other, and a belt 45 that is wound around the primary pulley 43 and the secondary pulley 44.

The primary pulley 43 is arranged to face the fixed sheave 51 fixed to the primary shaft 41 with the belt 45 sandwiched between the fixed sheave 51, and is supported by the primary shaft 41 so as to be movable in the axial direction and non-relatively rotatable. It is equipped with 52. A cylinder 53 fixed to the primary shaft 41 is provided on the opposite side of the movable sheave 52 from the fixed sheave 51, and a hydraulic chamber 54 is formed between the movable sheave 52 and the cylinder 53.

The secondary pulley 44 is arranged so as to face the fixed sheave 55 fixed to the secondary shaft 42 with the belt 45 sandwiched between the fixed sheave 55, and is supported by the secondary shaft 42 so as to be movable in the axial direction and non-relatively rotatable. It is equipped with 56. A cylinder 57 fixed to the secondary shaft 42 is provided on the opposite side of the movable sheave 56 from the fixed sheave 55, and a hydraulic chamber 58 is formed between the movable sheave 56 and the cylinder 57. In the direction of the rotation axis, the positional relationship between the fixed sheave 55 and the movable sheave 56 is reversed from the positional relationship between the fixed sheave 51 and the movable sheave 52 of the primary pulley 43.

In the belt transmission mechanism 33, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 is controlled, respectively, and the groove widths of the primary pulley 43 and the secondary pulley 44 are changed. The belt gear ratio (pulley ratio) is continuously and steplessly changed.

Specifically, when the belt gear ratio is reduced, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is increased. As a result, the movable sheave 52 of the primary pulley 43 moves toward the fixed sheave 51, and the distance (groove width) between the fixed sheave 51 and the movable sheave 52 becomes smaller. Along with this, the winding diameter of the belt 45 with respect to the primary pulley 43 becomes large, and the distance (groove width) between the fixed sheave 55 and the movable sheave 56 of the secondary pulley 44 becomes large. As a result, the pulley ratio between the primary pulley 43 and the secondary pulley 44 becomes small.

When the belt gear ratio is increased, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 is lowered. As a result, the thrust ratio, which is the ratio of the thrust (primary thrust) of the primary pulley 43 to the thrust of the secondary pulley 44 (secondary thrust), becomes smaller, and the distance between the fixed sheave 55 and the movable sheave 56 of the secondary pulley 44 becomes smaller. , The distance between the fixed sheave 51 and the movable sheave 52 becomes large. As a result, the pulley ratio between the primary pulley 43 and the secondary pulley 44 becomes large.

On the other hand, the thrust of the primary pulley 43 and the secondary pulley 44 needs to have a magnitude such that slip (belt slip) does not occur between the primary pulley 43 and the secondary pulley 44 and the belt 45. Therefore, the hydraulic pressure supplied to the hydraulic chamber 54 of the primary pulley 43 and the hydraulic chamber 58 of the secondary pulley 44 is controlled so that the necessary and sufficient pinching pressure that does not cause belt slippage can be obtained.

The front reduction gear mechanism 34 is configured to reverse and decelerate the power input to the input shaft 31 and transmit it to the primary shaft 41. Specifically, the front reduction gear mechanism 34 has a larger diameter and a larger number of teeth than the input shaft gear 61 supported by the input shaft 31 so as not to rotate relative to the input shaft gear 61, and is spline-fitted to the primary shaft 41. Includes a primary shaft gear 62 that is supported by the relative non-rotatable gear and meshes with the input shaft gear 61.

The planetary gear mechanism 35 includes a sun gear 71, a carrier 72, and a ring gear 73. The sun gear 71 is supported on the secondary shaft 42 so as not to rotate relative to each other by spline fitting. The carrier 72 is externally fitted to the output shaft 32 so as to be relatively rotatable. The carrier 72 rotatably supports a plurality of pinion gears 74. A plurality of pinion gears 74 are arranged on the circumference and mesh with the sun gear 71. The ring gear 73 has an annular shape that collectively surrounds a plurality of pinion gears 74, and meshes with each pinion gear 74 from the outside in the radial direction of rotation of the secondary shaft 42. Further, an output shaft 32 is connected to the ring gear 73, and the ring gear 73 is provided so as to be integrally rotatable around the same rotation axis as the output shaft 32.

The split transmission mechanism 36 is a parallel shaft gear mechanism including a split drive gear 81 and a split driven gear 82 that meshes with the split drive gear 81.

The split drive gear 81 is externally fitted to the input shaft 31 so as to be relatively rotatable.

The split driven gear 82 is provided so as to be integrally rotatable around the same rotation axis as the carrier 72 of the planetary gear mechanism 35. The split driven gear 82 is formed to have a smaller diameter than the split drive gear 81, and has a smaller number of teeth than the split drive gear 81.

Further, the parking gear 83 is supported on the output shaft 32 so as to be relatively non-rotatable. A parking pole (not shown) is provided around the parking gear 83. When the parking pole engages with the tooth groove of the parking gear 83, the rotation of the parking gear 83 is restricted (parking lock), and when the parking pole is disengaged from the tooth groove of the parking gear 83, the rotation of the parking gear 83 is restricted. Allowed (parking lock released).

Further, the continuously variable transmission 4 includes clutches C1 and C2 and a brake B1.

The clutch C1 is hydraulically switched between an engaged state in which the input shaft 31 and the split drive gear 81 are directly connected (coupled so as to be integrally rotatable) and an released state in which the direct connection is released.

The clutch C2 is hydraulically switched between an engaged state in which the sun gear 71 of the planetary gear mechanism 35 and the ring gear 73 are directly connected (coupled so as to be integrally rotatable) and an released state in which the direct connection is released.

The brake B1 is hydraulically switched between an engaged state in which the carrier 72 of the planetary gear mechanism 35 is braked and an released state in which the carrier 72 is allowed to rotate.

<Power transmission mode>
FIG. 2 is a diagram showing the states of the clutches C1 and C2 and the brake B1 when the vehicle 1 is moving forward and backward. FIG. 3 is a collinear diagram showing the relationship between the rotation speeds (rotational speeds) of the sun gear 71, the carrier 72, and the ring gear 73 of the planetary gear mechanism 35. FIG. 4 is a diagram showing the relationship between the belt gear ratio by the belt gear shifting mechanism 33 and the total gear ratio of the continuously variable transmission 4 as a whole.

In FIG. 2, “◯” indicates that the clutches C1 and C2 and the brake B1 are in the engaged state. “X” indicates that the clutches C1 and C2 and the brake B1 are in the released state.

A shift lever (select lever) is arranged in the vehicle interior of the vehicle 1 at a position where the driver can operate the vehicle. In the movable range of the shift lever, for example, each range position of P (parking) position, R (reverse) position, N (neutral) position and D (drive) position is provided in this order in a row.

When the shift lever is in the P position, the clutches C1 and C2 and the brake B1 are all released, and the parking gear 83 is fixed, so that the P range (P range), which is one of the shift ranges of the continuously variable transmission 4, is set. Parking range) is configured. Further, when the shift lever is in the N position, all of the clutches C1 and C2 and the brake B1 are released, and the parking lock gear is not fixed, so that N is one of the shift ranges of the continuously variable transmission 4. A range (neutral range) is configured. When both the clutch C1 and the brake B1 are released, the power of the engine 2 is transmitted to the secondary shaft 42 and the secondary shaft 42 rotates, but the sun gear 71 and the pinion gear 74 of the planetary gear mechanism 35 slip and the engine The power of 2 is not transmitted to the drive wheels 7L and 7R.

When the shift lever is in the D position, the D range (forward range), which is one of the shift ranges of the continuously variable transmission 4, is configured. The power transmission mode in this D range includes a belt mode (an example of a first mode) and a split mode (an example of a second mode). The belt mode and the split mode are switched by switching between the state in which the clutch C1 is engaged and the state in which the clutch C2 is engaged (replacement of the clutches C1 and C2).

In the belt mode, as shown in FIG. 2, the clutch C1 and the brake B1 are released and the clutch C2 is engaged. As a result, the split drive gear 81 is separated from the input shaft 31, the carrier 72 of the planetary gear mechanism 35 becomes free (free rotation state), and the sun gear 71 of the planetary gear mechanism 35 and the ring gear 73 are directly connected.

The power input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34 and transmitted to the primary shaft 41 of the belt transmission mechanism 33 to rotate the primary shaft 41 and the primary pulley 43. The rotation of the primary pulley 43 is transmitted to the secondary pulley 44 via the belt 45 to rotate the secondary pulley 44 and the secondary shaft 42. Since the sun gear 71 of the planetary gear mechanism 35 and the ring gear 73 are directly connected, the sun gear 71, the ring gear 73, and the output shaft 32 rotate integrally with the secondary shaft 42. Therefore, in the belt mode, as shown in FIGS. 3 and 4, the total gear ratio of the entire continuously variable transmission 4 is the front reduction ratio (rotation speed of the input shaft 31 / primary) to the belt gear ratio of the belt transmission mechanism 33. It matches the value multiplied by the number of rotations of the shaft 41).

In the split mode, as shown in FIG. 2, the clutch C1 is engaged and the clutch C2 and the brake B1 are released. As a result, the input shaft 31 and the split drive gear 81 are coupled, and the rotation of the input shaft 31 can be transmitted to the carrier 72 of the planetary gear mechanism 35 via the split drive gear 81 and the split driven gear 82, and the planetary gear mechanism The sun gear 71 of 35 and the ring gear 73 are separated.

The power input to the input shaft 31 is accelerated and transmitted from the split drive gear 81 to the carrier 72 of the planetary gear mechanism 35 via the split driven gear 82. The power transmitted to the carrier 72 is divided and transmitted from the carrier 72 to the sun gear 71 and the ring gear 73. The power of the sun gear 71 is transmitted to the primary shaft gear 62 via the secondary shaft 42, the secondary pulley 44, the belt 45, the primary pulley 43 and the primary shaft 41, and is transmitted from the primary shaft gear 62 to the input shaft gear 61. Therefore, in the belt mode, the input shaft gear 61 becomes the drive gear and the primary shaft gear 62 becomes the driven gear, whereas in the split mode, the primary shaft gear 62 becomes the drive gear and the input shaft gear 61 becomes the driven gear. ..

Since the gear ratio between the split drive gear 81 and the split driven gear 82 is constant and constant (fixed), in the split mode, if the power input to the input shaft 31 is constant, the carrier 72 of the planetary gear mechanism 35 rotates. Is kept at a constant speed. Therefore, when the belt gear ratio is increased, the rotation speed of the sun gear 71 of the planetary gear mechanism 35 decreases. Therefore, as shown by the broken line in FIG. 3, the rotation speed of the ring gear 73 (output shaft 32) of the planetary gear mechanism 35 is decreased. Goes up. As a result, in the split mode, as shown in FIG. 4, the larger the belt gear ratio of the belt transmission mechanism 33, the smaller the total gear ratio of the stepless transmission 4, and the sensitivity of the total gear ratio to the belt gear ratio ( The ratio of the total gear ratio change to the belt gear ratio change) is lower than in the belt mode.

The rotation of the output shaft 32 in the belt mode and the split mode is transmitted to the differential gear 5 via the output gear 37. As a result, the drive shafts 6L and 6R and the drive wheels 7L and 7R of the vehicle 1 rotate in the forward direction.

When the shift lever is in the R position, the R range (reverse range), which is one of the shift ranges of the continuously variable transmission 4, is configured. In the R range, as shown in FIG. 2, the clutches C1 and C2 are released and the brake B1 is engaged. As a result, the split drive gear 81 is disconnected from the input shaft 31, the sun gear 71 of the planetary gear mechanism 35 and the ring gear 73 are disconnected, and the carrier 72 of the planetary gear mechanism 35 is braked.

The power input to the input shaft 31 is reversed and decelerated by the front reduction gear mechanism 34, transmitted to the primary shaft 41 of the belt speed change mechanism 33, and transmitted from the primary shaft 41 via the primary pulley 43, the belt 45, and the secondary pulley 44. The sun gear 71 of the planetary gear mechanism 35 is rotated integrally with the secondary shaft 42. Since the carrier 72 of the planetary gear mechanism 35 is braked, when the sun gear 71 rotates, the ring gear 73 of the planetary gear mechanism 35 rotates in the opposite direction to the sun gear 71. The rotation direction of the ring gear 73 is opposite to the rotation direction of the ring gear 73 during forward movement (belt mode and split mode). Then, the output shaft 32 rotates integrally with the ring gear 73. The rotation of the output shaft 32 is transmitted to the differential gear 5 via the output gear 37. As a result, the drive shafts 6L and 6R and the drive wheels 7L and 7R of the vehicle 1 rotate in the reverse direction.

When the vehicle 1 moves forward, the rotation speed of the sun gear 71 and the rotation speed of the ring gear 73 match due to the direct connection between the sun gear 71 of the planetary gear mechanism 35 and the ring gear 73, whereas when the vehicle 1 moves backward, the planetary gear mechanism 35 Due to the configuration of, the rotation speed of the ring gear 73 is always lower than the rotation speed of the sun gear 71. Therefore, in the R range, the gear ratio is larger than the maximum pulley ratio, and when the maximum pulley ratio is configured in the D range and the R range, the gear ratio is larger when the vehicle 1 is moving backward and compared to when moving forward. Therefore, the power output from the output shaft 32 becomes large.

<Vehicle control system>
FIG. 5 is a block diagram showing the configuration of the control system of the vehicle 1.

The vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU includes a microcomputer (microcontroller unit), and the microcomputer has, for example, a non-volatile memory such as a CPU and a flash memory and a volatile memory such as a DRAM (Dynamic Random Access Memory). The plurality of ECUs are connected so as to be capable of bidirectional communication by a CAN (Controller Area Network) communication protocol. FIG. 5 shows one ECU 91 among the plurality of ECUs.

The unit including the torque converter 3 and the continuously variable transmission 4 is provided with a hydraulic circuit 92 for supplying hydraulic pressure to each part. The ECU 91 controls various valves and the like included in the hydraulic circuit 92 for shifting control of the continuously variable transmission 4 and the like.

Various sensors required for control are connected to the ECU 91. As an example of the sensor, the ECU 91 has an engine rotation sensor 93 that outputs a pulse signal synchronized with the rotation of the engine 2 (rotation of the crank shaft) as a detection signal, and an accelerator that outputs a detection signal according to the operation amount of the accelerator pedal. The sensor 94 and the vehicle speed sensor 95 that outputs a pulse signal synchronized with the rotation of the rotating body that rotates with the traveling of the vehicle 1 as a detection signal are connected.

Further, in addition to the information acquired from the detection signals input from various sensors, information necessary for control is input to the ECU 91 from other ECUs. As for the information input to the ECU 91 from another ECU, a sensor for acquiring the information may be connected to the ECU 91, and the information may be acquired from the detection signal of the sensor in the ECU 91.

<Shift control>
The total gear ratio of the continuously variable transmission 4 is controlled by changing the belt gear ratio by the ECU 91 and engaging / disengaging the clutches C1 and C2 and the brake B1. In this shift control, first, the target rotation speed according to the accelerator opening degree and the vehicle speed is set based on the shift diagram. The shift line diagram is a map that defines the relationship between the accelerator opening and the vehicle speed and the target rotation speed, and is stored in the ROM of the ECU 91. The accelerator opening degree is calculated from the detection signal of the accelerator sensor 94. The vehicle speed is calculated from the detection signal of the vehicle speed sensor 95. When the target rotation speed is set, the rotation speed input to the input shaft 31, that is, the target gear ratio that is the target of the total gear ratio that matches the turbine rotation speed with the target rotation speed is obtained, and according to the target gear ratio. The target of the belt gear ratio is set.

After that, based on the target of the belt gear ratio, the command values of the primary pressure which is the hydraulic pressure supplied to the movable sheave 52 of the primary pulley 43 and the secondary pressure which is the hydraulic pressure supplied to the movable sheave 56 of the secondary pulley 44 are set. , The primary pressure and the secondary pressure are controlled so that the deviation between the target of the belt gear ratio and the actual belt gear ratio approaches zero based on each command value. The actual belt gear ratio is obtained by dividing the primary rotation speed by the secondary rotation speed.

When the total gear ratio is changed across a split point equal to the split gear ratio, which is the gear ratio between the split drive gear 81 and the split driven gear 82, the total gear ratio can be changed by switching between the belt mode and the split mode. (Hereinafter, simply referred to as "mode switching") is accompanied. Mode switching is achieved by switching the engagement of the clutches C1 and C2. That is, by controlling the hydraulic pressure supplied to the clutches C1 and C2, the clutch C1 (engaged side) in the disengaged state is engaged, and the clutch C2 (disengaged side) in the engaged state is released, so that the belt mode is released. Switch to split mode. On the contrary, the clutch C1 (disengaged side) in the engaged state is released, and the clutch C2 (engaged side) in the disengaged state is engaged, so that the split mode is switched to the belt mode.

<Clutch configuration>
FIG. 6 is a cross-sectional view showing the configuration of the clutch C2.

The clutch C2 includes a clutch drum 101, a clutch hub 102, and a clutch piston 103.

The inner peripheral end of the clutch drum 101 is fixed to the output shaft 32, extends in the shaft radial direction from the output shaft 32, and the outer peripheral end portion is in the rotation axis direction of the output shaft 32 (hereinafter, simply referred to as "rotation axis direction"). ), That is, it bends and extends to one side, that is, the secondary pulley 44 side (see FIG. 1).

The clutch hub 102 is supported by the sun gear 71 of the planetary gear mechanism 35 so as not to rotate relative to each other. The clutch hub 102 extends from the sun gear 71 in the axial direction of the shaft, and its outer peripheral end portion bends and extends toward the secondary pulley 44. The outer peripheral end portion of the clutch hub 102 faces the outer peripheral end portion of the clutch drum 101 at a distance from the inside in the axial radial direction.

The clutch piston 103 is provided between the clutch drum 101 and the clutch hub 102 so as to be movable in the direction of the rotation axis. The clutch piston 103 is in liquid-tight contact with the clutch drum 101, and an oil chamber 104 to which hydraulic pressure acting on the clutch piston 103 is supplied is formed between the clutch drum 101 and the clutch piston 103. .. Further, a return spring 105 is provided on the side opposite to the oil chamber 104 with respect to the clutch piston 103, and the clutch piston 103 is elastic on the side opposite to the secondary pulley 44 side, that is, on the engine 2 side by the return spring 105. Is being urged.

A substantially annular clutch plate 106 held by the clutch drum 101 and a substantially annular clutch disk held by the clutch hub 102 in a space sandwiched between the outer peripheral end of the clutch drum 101 and the clutch hub 102 in the axial radial direction. 107 and 107 are arranged alternately from one side and the opposite side in the direction of the rotation axis, that is, from the engine 2 side (see FIG. 1). A substantially annular cushioning spring 108 is arranged on one side of the clutch plate 66 at the end on one side in the direction of the rotation axis. The outer peripheral end of the cushioning spring 108 is held by the clutch drum 101.

When hydraulic pressure is supplied to the oil chamber 104, the hydraulic pressure causes the clutch piston 103 to move forward against the elastic force of the return spring 105. As the movement of the clutch piston 103 progresses, the clutch piston 103 comes into contact with the cushioning spring 108. When the hydraulic pressure rises, the clutch piston 103 presses the cushioning spring 108, and the cushioning spring 108 begins to elastically deform. After that, the clutch piston 103 moves to the front side against the resultant force of the elastic forces of the return spring 105 and the cushioning spring 108 as the hydraulic pressure rises. When the elastic deformation of the cushioning spring 108 is completed, the clutch piston 103 presses the clutch plate 106 via the cushioning spring 108, and the clutch plate 106 and the clutch disk 107 are in pressure contact with each other, so that the clutch C2 begins to have a transmission torque capacity. .. After that, as the pressure contact force between the clutch plate 106 and the clutch disc 107 increases due to the increase in hydraulic pressure, the transmission torque capacity of the clutch C2 increases. When the cushioning spring 108 is pushed completely by the clutch piston 103 (when the elastic deformation of the cushioning spring 108 stops), the movement of the clutch piston 103 stops. When the clutch plate 106 and the clutch disc 107 are in pressure contact with each other without causing slippage, the clutch C2 is in a completely engaged state.

<Switching from split mode to belt mode>
FIG. 7 is a diagram showing a time change of the execution state of the switching control, the release side control pressure, and the engagement side control pressure at the time of switching from the split mode to the belt mode.

In the ECU 91, when the target gear ratio is set to a switching value (see FIG. 4) which is a belt gear ratio at the split point, that is, a value equal to or less than the switching value in the belt mode, switching from the belt mode to the split mode is determined. Will be done. Further, in the ECU 91, when the target gear ratio is set to a value equal to or higher than the switching value in the split mode, the switching from the split mode to the belt mode is determined.

In the split mode, the ECU 91 determines whether or not the belt gear ratio (target) corresponding to the target gear ratio has changed from the standby threshold value or more to the standby threshold value or less. The wait threshold is set to a value larger than the switching value. Therefore, in the split mode, when the belt gear ratio is decreasing toward the switching value, the belt gear ratio is changed from the standby threshold value or higher to the standby threshold value before the ECU 91 determines the switching from the split mode to the belt mode. It is detected that the value has changed to less than.

When the belt gear ratio changes from the standby threshold value or more to the standby threshold value or less, the switching control by the ECU 91 is started (time T1). By starting the switching control, the engagement side control pressure, which is the target value of the hydraulic pressure supplied to the clutch C2, is raised from 0 to a filling pressure close to the engagement pressure. Then, the engagement side control pressure is held at the filling pressure for a predetermined period (period T1-T2). While the engagement side control pressure is held at the filling pressure, oil is filled in the oil chamber 104 of the clutch C2 and the oil passage that supplies hydraulic pressure to the oil chamber 104. After a lapse of a predetermined period, the engagement side control pressure is lowered from the filling pressure to the standby pressure (time T2) and held at the standby pressure. When the engagement side control pressure is held at the standby pressure, the clutch piston 103 of the clutch C2 is pushed and moved by hydraulic pressure. The standby pressure is set to a hydraulic pressure that applies a force equal to or less than the elastic force of the return spring 105 to the clutch piston 103 while the clutch piston 103 has moved to a position where it abuts on the cushioning spring 108. Therefore, when the clutch piston 103, which is pushed by hydraulic pressure and moves, comes into contact with the cushioning spring 108, it stops without further compressing the return spring 105. As a result, the invalid stroke of the clutch piston 103 is eliminated, and the clutch C2 does not have a transmission torque capacity.

In this embodiment, the cushioning spring 108 is included in the concept of the "plate" of the present invention.

When the belt gear ratio corresponding to the target gear ratio returns to the standby threshold value or higher from the state where the engagement side control pressure is held at the standby pressure, the oil pressure is removed from the oil chamber 104 of the clutch C2 by the ECU 91, and switching control is performed. Is terminated.

When the target gear ratio is set to a value equal to or higher than the switching value and the switching from the split mode to the belt mode is determined while the engaging side control pressure is held at the standby pressure (time T3), The engagement side control pressure is gradually increased from the standby pressure to the engagement pressure (period T3-T4). As a result, the hydraulic pressure supplied to the oil chamber 104 of the clutch C2 gradually increases, and the transmission torque capacity of the clutch C2 increases accordingly. When the clutch plate 106 and the clutch disc 107 are in a state of pressure contact without slipping, the clutch C2 is in a completely engaged state.

On the other hand, the release side control pressure, which is the target value of the hydraulic pressure supplied to the clutch C1, is gradually reduced from the engagement pressure to 0 (period T3-T5). In order to suppress the rotation of the turbine runner 23 of the torque converter 3 from rising during the gradual decrease, a period is provided in which the release side control pressure is kept constant.

When the clutch C2 is engaged and the clutch C1 is released, the belt mode is configured and the switching from the split mode to the belt mode is completed (time T5).

<Action effect>
As described above, in the shift control, the target gear ratio, which is the target of the total gear ratio, is set, and the belt gear ratio is changed so that the total gear ratio matches the target gear ratio. When the target gear ratio equal to or less than the switching value is set in the belt mode, the switching from the belt mode to the split mode is determined. When the target gear ratio equal to or higher than the switching value is set in the split mode, the switching from the split mode to the belt mode is determined.

In the split mode, the belt gear ratio (target) according to the target gear ratio changes from the standby threshold value larger than the switching value to less than the standby threshold value before the switching from the split mode to the belt mode is determined. Then, hydraulic pressure is supplied to the clutch C2, and the clutch C2 is in a state in which a standby pressure equal to or lower than the hydraulic pressure at which the transmission torque capacity is started is applied.

Since the clutch C2 is on standby in this state, when the switch from the split mode to the belt mode is determined, the clutch C2 is promptly engaged by increasing the hydraulic pressure supplied to the clutch C2 according to the determination. In combination, the switch from split mode to belt mode can be completed. Therefore, the time required from the determination of switching from the split mode to the belt mode until the switching is completed (total switching shift time) can be shortened as compared with the conventional case. As a result, the responsiveness of switching from the split mode to the belt mode to the depression of the accelerator pedal can be improved, and by extension, the responsiveness of acceleration of the vehicle 1 can be improved.

<Modification example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.

For example, in the above-described embodiment, the hydraulic pressure is supplied to the clutch C2 in response to the change of the belt gear ratio according to the target gear ratio from the standby threshold value or more to the standby threshold value or less. The hydraulic pressure may be supplied to the clutch C2 according to the change of the actual belt gear ratio, which is a value, from the standby threshold value or more to the standby threshold value or less. The actual belt gear ratio can be obtained by dividing the primary rotation speed by the secondary rotation speed.

Further, in the above-described embodiment, the configuration in which the power is transmitted by branching to the first power transmission path via the split shift mechanism 36 and the second power transmission path via the belt shift mechanism 33 has been taken up, but the split shift has been taken up. The mechanism 36 is not limited to the parallel shaft type gear mechanism including the split drive gear 81 and the split driven gear 82, and may be a mechanism other than the gear mechanism such as a belt mechanism. When a belt mechanism is adopted, the belt mechanism may have a fixed gear ratio or a variable gear ratio.

In addition, various design changes can be made to the above-mentioned configuration within the scope of the matters described in the claims.

4: Continuously variable transmission 31: Input shaft 32: Output shaft 33: Belt speed change mechanism 91: ECU (control device, target speed change ratio setting means, belt speed change speed change means, switching determination means, engagement standby means)
103: Clutch piston 104: Oil chamber 105: Return spring 106: Clutch plate (plate)
107: Clutch disc (disc)
108: Cushioning spring (plate)
C1: Clutch (first engaging element)
C2: Clutch (second engaging element)

Claims (2)

The first engaging element, which is interposed on the first power transmission path between the input shaft and the output shaft and is engaged / disengaged by hydraulic pressure, and the second between the input shaft and the output shaft. It comprises a second engaging element that is interposed in the power transmission path and is hydraulically engaged / disengaged, has a belt speed change mechanism on the second power transmission path, and releases the first engaging element and said. Due to the engagement of the second engagement element, the larger the belt gear ratio by the belt transmission mechanism, the larger the total gear ratio between the input shaft and the output shaft becomes the first mode, and the first engagement is performed. By engaging the elements and releasing the second engaging element, the second mode is set in which the total gear ratio becomes smaller as the belt gear ratio is larger, and when the belt gear ratio is a constant switching value, the first mode is set. A control device for controlling a stepless transmission configured so that the total gear ratio does not change even when the first mode and the second mode are switched.
The target gear ratio setting means for setting the target gear ratio, which is the target of the total gear ratio, and the target gear ratio setting means.
A belt gear ratio changing means for changing the belt gear ratio so that the total gear ratio matches the target gear ratio set by the target gear ratio setting means.
In the first mode, if the target gear ratio set by the target gear ratio setting means is equal to or less than the switching value, switching from the first mode to the second mode is determined, and in the second mode, the switching is determined. If the target gear ratio set by the target gear ratio setting means is equal to or greater than the switching value, the switching determination means for determining the switching from the second mode to the first mode and the switching determination means.
In the second mode, before the switching from the second mode to the first mode is determined by the switching determination means, the belt gear ratio is changed from a standby threshold value larger than the switching value to less than the standby threshold value. In response to the change, hydraulic pressure is supplied to the second engaging element, and a standby pressure equal to or lower than the hydraulic pressure at which the second engaging element begins to have a transmission torque capacity acts on the second engaging element. , A control device comprising an engagement waiting means for making the second engaging element stand by in the state. The second engaging element is provided so that the plate and the disc face each other, and the piston moves against the elastic force of the return spring by the hydraulic pressure supplied to the oil chamber, and the piston moves the plate to the disc. A frictional engagement element that engages by pressing against
The control device according to claim 1, wherein the standby pressure is set to a hydraulic pressure that applies a force equal to or less than the elastic force of the return spring to the piston in a state where the piston moves to a position where the piston abuts on the plate. ..

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