JP6973917B2 - Control device for continuously variable transmission - Google Patents

Description

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

A continuously variable transmission (CVT) is widely known as a transmission mounted on a vehicle.

The belt-type continuously variable transmission has a configuration in which an endless belt is wound around a primary pulley on the input side and a secondary pulley on the output side. Each pulley of the primary pulley and the secondary pulley is provided with a fixed sheave and a movable sheave facing the fixed sheave with a belt sandwiched between them. In this continuously variable transmission, the winding diameter of the belt for each pulley is changed by moving each movable sheave of the primary pulley and the secondary pulley in the direction of the rotation axis and continuously changing the groove width of each pulley. The gear ratio (pulley ratio) can be continuously changed steplessly.

Japanese Unexamined Patent Publication No. 2010-11239

However, in a CVT vehicle equipped with a continuously variable transmission, the engine brake may be weaker during deceleration, especially when descending a slope, as compared with an MT vehicle equipped with a manual transmission (MT). In an MT vehicle, when the engine brake is weak, the deceleration can be increased by switching the shift stage to a low speed stage, but in a general CVT vehicle, such a downshift is impossible.

In a continuously variable transmission, it is also possible to change the gear ratio stepwise by controlling the groove width of each pulley to be changed stepwise. Some CVT vehicles have a plurality of pseudo gears having fixed gear ratios different from each other, and like MT vehicles, the gears can be switched by a shift operation. However, since the deceleration of the CVT vehicle is insufficient, when the foot brake is used, the brake operation must be performed in addition to the shift operation, which makes the operation complicated. Also, if foot brakes are used extensively, brake fade may occur.

An object of the present invention is to provide a continuously variable transmission control device capable of obtaining deceleration by engine braking according to the driver's intention by simple and intuitive operation.

In order to achieve the above object, the continuously variable transmission control device according to the present invention is used in a vehicle equipped with a continuously variable transmission capable of continuously shifting the power from the engine, and the continuously variable transmission is used. A speed change means that sets a target value according to the vehicle speed and accelerator opening of the vehicle and sets the gear ratio of the continuously variable transmission to the gear ratio corresponding to the target value, and the continuously variable transmission. The second operating member, which is provided separately from the first operating member operated to select the shift range of the above, is operated between the off position and the on position, and the second operating member is operated according to the operation of the second operating member. It includes a changing means for changing the gear ratio corresponding to the target value so as to increase or decrease by a predetermined amount.

According to this configuration, a target value is set according to the vehicle speed and the accelerator opening degree of the vehicle. Then, usually, the gear ratio of the continuously variable transmission is set to the gear ratio corresponding to the target value.

Apart from the first operating member operated to select the shift range of the continuously variable transmission, a second operating member is operably provided between the off position and the on position. When the second operating member is operated, the gear ratio of the continuously variable transmission is increased by a predetermined amount from the gear ratio corresponding to the target value, that is, the gear ratio according to the vehicle speed and the accelerator opening. By increasing the gear ratio by a predetermined amount, the engine speed increases, the engine brake acts on the drive system of the vehicle, and the vehicle decelerates. Therefore, the deceleration by the engine brake can be obtained according to the driver's intention by a simple and intuitive operation.

When the second operating member is operated, the gear ratio of the continuously variable transmission may be reduced by a predetermined amount from the gear ratio corresponding to the target value, that is, the gear ratio according to the vehicle speed and the accelerator opening. By reducing the gear ratio by a predetermined amount, the engine speed decreases, the engine brake acting on the drive system of the vehicle weakens, and the deceleration of the vehicle decreases. Therefore, the deceleration by the engine brake can be obtained according to the driver's intention by a simple and intuitive operation.

The changing means may set a predetermined amount to a constant value. However, the control device further includes an operation amount detecting means for detecting the operation amount of the second operating member, and the changing means sets a predetermined amount to a large value as the operation amount detected by the operation amount detecting means increases. Is preferable.

In a vehicle equipped with a continuously variable transmission, a B range (brake range) is provided in addition to the D range (drive range) as the forward range of the continuously variable transmission. In the B range, the gear ratio is set so that the engine speed is maintained higher than that in the D range according to the vehicle speed and the accelerator opening, and a stronger engine brake than in the D range can be obtained. However, even if the CVT vehicle shifts from the D range to the B range when descending a slope, the deceleration is often slightly increased, which is insufficient in many cases. If the difference in gear ratio between the D range and the B range is set large, the deceleration of the CVT vehicle will be too large when the slope of the downhill road is small.

With the latter configuration, the larger the driver operates the second operating member, the larger the gear ratio (shifting to the low side) can be achieved. Therefore, unlike the B range, deceleration can be obtained according to the driver's intention.

The changing means may set a predetermined amount to a larger value as the time during which the second operating member continues to be operated is extended.

According to this configuration, the longer the operation time of the second operating member by the driver, the larger the gear ratio can be. Therefore, it is possible to obtain a deceleration according to the intention of the driving vehicle.

When the control device for the continuously variable transmission according to the present invention is mounted on the vehicle, the B range may be omitted from the shift range of the continuously variable transmission. By omitting the B range, the control content of the continuously variable transmission can be simplified.

According to the present invention, deceleration by engine braking can be obtained according to the driver's intention by a simple and intuitive operation. By actively using the engine brake, it is possible to suppress the occurrence of fade phenomenon due to the heavy use of the foot brake.

It is a figure which shows the main part of the structure of the vehicle which mounted the control device which concerns on one Embodiment of this invention. It is a shift line diagram which shows the relationship between the accelerator opening and the vehicle speed, and a target engine rotation speed. It is a figure which shows an example of the time change of the lever operation amount and the gear ratio of a continuously variable transmission. It is a figure which shows the main part of the structure of the vehicle which mounted the control device which concerns on other embodiment of this invention. It is a figure which shows an example of the time change of the lever operation amount and the gear ratio of a continuously variable transmission in the configuration shown in FIG.

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

<Vehicle drive system>
FIG. 1 is a diagram showing a main part of a configuration of a vehicle 1 equipped with a control device according to an embodiment of the present invention.

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.

Further, the vehicle 1 is equipped with a torque converter 3 and a belt-type continuously variable transmission (CVT) 4 in order to transmit the output of the engine 2 to the drive wheels.

The torque converter 3 includes a pump impeller 11, a turbine runner 12, and a lockup mechanism (lockup clutch) 13.

The output shaft (crankshaft) of the engine 2 is connected to the pump impeller 11, and the pump impeller 11 is provided so as to be integrally rotatable around the same rotation axis as the output shaft. The turbine runner 12 is rotatably provided about the same rotation axis as the pump impeller 11. The lockup mechanism 13 is provided to directly connect / separate the pump impeller 11 and the turbine runner 12. When the lockup mechanism 13 is engaged (lockup on), the pump impeller 11 and the turbine runner 12 are directly connected, and when the lockup mechanism 13 is released (lockup off), the pump impeller 11 and the turbine runner 12 are directly connected. And are separated.

In the lock-up-off state, when the pump impeller 11 is rotated by the output of the engine 2, oil flows from the pump impeller 11 to the turbine runner 12. This flow of oil is received by the turbine runner 12, and the turbine runner 12 rotates. At this time, the amplification action of the torque converter 3 occurs, and a torque larger than the output (torque) of the engine is generated in the turbine runner 12.

In the lockup-on state, the pump impeller 11 and the turbine runner 12 rotate together due to the output of the engine 2.

The continuously variable transmission 4 includes a primary shaft 21, a secondary shaft 22, a primary pulley 23, a secondary pulley 24, and a belt 25.

The primary shaft 21 and the secondary shaft 22 are parallel to each other and extend in the same direction as the rotation axis of the pump impeller 11 of the torque converter 3 and the turbine runner 12. The primary pulley 23 is supported by the primary shaft 21 so as not to rotate relative to each other. The secondary pulley 24 is supported by the secondary shaft 22 so as not to rotate relative to each other. The belt 25 is wound around the primary pulley 23 and the secondary pulley 24.

The rotation of the turbine runner 12 of the torque converter 3 is input to the primary shaft 21 to rotate the primary pulley 23 integrally with the primary shaft 21. The rotation of the primary pulley 23 is transmitted to the secondary pulley 24 via the belt 25, and the secondary shaft 22 is rotated integrally with the secondary pulley 24. Then, the rotation of the secondary shaft 22 is input to the differential gear (not shown) and transmitted from the differential gear to the drive wheels via the drive shaft. As a result, the drive wheels rotate in the forward direction or the reverse direction.

The primary pulley 23 includes a fixed sheave 26 fixed to the primary shaft 21 and a movable sheave 27 arranged on the fixed sheave 26 with a belt 25 interposed therebetween and supported by the primary shaft 21 so as to be movable in the axial direction thereof. There is. The secondary pulley 24 includes a fixed sheave 28 fixed to the secondary shaft 22 and a movable sheave 29 arranged on the fixed sheave 28 with the belt 25 interposed therebetween and supported by the secondary shaft 22 so as to be movable in the axial direction thereof. There is.

Due to the movement of the movable sheave 27 of the primary pulley 23, the groove width, which is the distance between the fixed sheave 26 and the movable sheave 27, continuously changes. Due to the movement of the movable sheave 29 of the secondary pulley 24, the groove width, which is the distance between the fixed sheave 28 and the movable sheave 29, continuously changes. By continuously changing the groove widths of the primary pulley 23 and the secondary pulley 24, the winding diameter of the belt for each pulley can be changed, and the gear ratio (pulley ratio) is continuously changed steplessly. be able to.

<Vehicle control system>
The vehicle 1 is provided with an ECU (Electronic Control Unit) 31 having a configuration including a microcomputer (microcontroller unit). The microcomputer has, for example, a CPU, ROM and RAM, a data flash (flash memory), and the like. FIG. 1 shows only one ECU 31 for controlling a drive transmission system including an engine 2, a torque converter 3, and a continuously variable transmission 4, but the vehicle 1 has an ECU 31 for controlling each part. A plurality of ECUs having the same configuration as the above are mounted. A plurality of ECUs including the ECU 31 are connected so as to be capable of bidirectional communication by a CAN (Controller Area Network) communication protocol.

Various sensors required for control are connected to the ECU 31. As an example, the ECU 31 receives, for example, an accelerator sensor 32 that outputs a detection signal according to the operation amount of the accelerator pedal operated by the driver, and a pulse signal synchronized with the rotation of the engine 2 (rotation of the crank shaft). An engine rotation sensor 33 that outputs as a detection signal and a vehicle speed sensor 34 that outputs a pulse signal synchronized with the rotation of a rotating body that rotates with the running of the vehicle 1 as a detection signal are connected.

The continuously variable transmission 4 has a shift range (shift range) including a P (parking) range, an R (reverse) range, an N (neutral) range, and a D (drive) range. For example, a shift lever (select lever) 35 for switching a shift range is arranged on an instrument panel in a vehicle interior. In the range of motion of the shift lever 35, P position, R position, N position and D position are set as shift positions corresponding to the shift range. A shift position sensor 36 that outputs a detection signal corresponding to each of the P, R, N, and D positions of the shift lever 35 is provided, and the shift position sensor 36 is connected to the ECU 31.

Further, a shift lever 37 is provided in the vicinity of the steering wheel in the vehicle interior. The shift lever 37 has, for example, a ring shape surrounding the steering shaft, and has an off position on the front side (back side when viewed from the driver) and an on position on the rear side (front side when viewed from the driver) in the axial direction of the steering shaft. It is possible to operate with. Further, the shift lever 37 is configured to be operated from the off position to the on position, and when the operation is released, the shift lever 37 is automatically returned from the on position to the off position, that is, a momentary operation is performed. In connection with the shift lever 37, a lever stroke sensor 38 that outputs a detection signal according to a stroke (operation amount) from the off position of the shift lever 37 is provided. A lever stroke sensor 38 is connected to the ECU 31.

The ECU 31 includes an engine control logic for controlling the engine 2 and a CVT control logic for controlling the torque converter 3 and the continuously variable transmission 4.

In the engine control logic, the ratio of the amount of depression to the maximum amount of depression of the accelerator pedal operated by the driver from the detection signal of the accelerator sensor 32, that is, 0% when the accelerator pedal is not depressed, is set to 0%, and the accelerator pedal is up to the maximum. The accelerator opening, which is a percentage of the time when the vehicle is stepped on, is acquired. Further, the engine rotation speed (the rotation speed of the engine 2) is acquired from the detection signal of the engine rotation sensor 33. Further, in the engine control logic, information may be acquired from the CVT control logic and other ECUs, and information may be acquired from the detection signals of other sensors. Then, the engine control logic controls the electronic throttle valve, injector, spark plug, etc. provided in the engine 2 for starting, stopping, and adjusting the output of the engine 2 based on various information.

In the CVT control logic, the vehicle speed of the vehicle 1 is acquired from the detection signal of the vehicle speed sensor 34. Further, in the CVT control logic, the position of the shift lever is acquired from the detection signal of the shift position sensor 36, and the operation amount from the off position of the shift lever 37 is acquired from the detection signal of the lever stroke sensor 38. Further, in the CVT control logic, information may be acquired from the engine control logic and other ECUs, and information may be acquired from the detection signals of other sensors. Then, based on various information, the CVT control logic is applied to each part of the torque converter 3 and the continuously variable transmission 4 for lock-up on / off control of the torque converter 3 and shift control of the continuously variable transmission 4. Various valves included in the hydraulic circuit for supplying hydraulic pressure are controlled.

<Shift control>
FIG. 2 is a shift line diagram showing the relationship between the accelerator opening degree and the vehicle speed and the target engine rotation speed.

When the shift lever is located in the D position and the shift range of the continuously variable transmission 4 is in the D range, the ECU 31 executes shift control for automatically shifting the gear ratio of the continuously variable transmission 4.

In the shift control, the gear ratio of the continuously variable transmission 4 is steplessly changed according to the accelerator opening degree and the vehicle speed. Specifically, a shift diagram used for shift control is stored in the memory of the ECU 31. The shift line diagram defines the relationship between the accelerator opening (AP) and the vehicle speed and the target engine speed, and the gear ratio according to the vehicle speed and the target engine speed is the minimum gear ratio γmin (highest) and the maximum. It is set to be within the range of the gear ratio γmax (lowest). In the continuously variable transmission control, the target engine rotation speed is set according to the accelerator opening and the vehicle speed from the shift line diagram, and the gear ratio is changed so that the engine rotation speed matches the target engine rotation speed.

As a result, the gear ratio can be continuously changed so that the engine speed is included in the highly efficient rotation range according to the changes in the accelerator opening and the vehicle speed, taking advantage of the continuously variable transmission control. It is possible to realize fuel-efficient driving.

<Lever operation>
FIG. 3 is a diagram showing an example of time changes in the lever operation amount and the gear ratio of the continuously variable transmission 4.

For example, when the vehicle 1 descends a slope, the driver may want to decelerate the vehicle 1 by engine braking. In this case, the driver can obtain the engine brake as intended by operating the shift lever 37 from the off position to the on position side. That is, the shift by the shift control according to the change of the accelerator opening degree and the vehicle speed and the shift by the operation of the shift lever 37 do not cooperate with each other, and the shift can be performed independently of each other.

When the shift lever 37 is operated from the off position to the on position side (time T1), the ECU 31 acquires the operation amount (lever operation amount) from the off position of the shift lever 37 from the detection signal of the lever stroke sensor 38. NS. Then, the ECU 31 sets a correction value for increasing the gear ratio of the continuously variable transmission 4. The correction value is set so that the correction value linearly increases as the operation amount of the shift lever 37 increases. At this time, as shown in FIG. 5, the correction value may be linearly increased in proportion to the operation amount of the shift lever 37, but is nth-order functional (n: 2 or more) with respect to the operation amount. Integer), for example, may be quadratically increased.

After that, the hydraulic circuit of the continuously variable transmission 4 is controlled, and the gear ratio of the continuously variable transmission 4 is corrected from the target gear ratio (the gear ratio in which the engine speed matches the target engine speed) in the above-mentioned shift control. It is increased by the minute (time T1-T2). Since the rotation speed of the engine 2 increases due to the increase in the gear ratio, the engine brake acts on the drive system of the vehicle 1, and the vehicle 1 is decelerated by the engine brake.

Since the correction value increases as the operation amount of the shift lever 37 increases, the driver turns on the shift lever 37 when the deceleration of the vehicle 1 due to the engine brake is smaller than the deceleration desired by the driver. By further operating the position side, the gear ratio of the continuously variable transmission 4 can be further increased and the engine brake can be strengthened.

When the shift lever 37 is held at the position where the deceleration desired by the driver is obtained, the correction value is kept constant and the gear ratio of the continuously variable transmission 4 is kept constant (time T2-T3). ).

When the deceleration of the vehicle 1 due to the engine brake is larger than the deceleration desired by the driver, the driver can weaken the engine brake by returning the shift lever 37 to the off position side. When the shift lever 37 is returned to the off position side, the amount of operation of the shift lever 37 from the off position decreases, and the correction value set by the ECU 31 decreases as the shift lever 37 decreases. As a result, the gear ratio of the continuously variable transmission 4 decreases (time T2-T3), so that the rotation speed of the engine 2 decreases and the engine brake weakens.

When the shift lever 37 is returned to the off position, the correction value set by the ECU 31 becomes 0, the shift ratio of the continuously variable transmission 4 becomes the target shift ratio in the shift control described above, and the engine brake is operated by operating the shift lever 37. Does not work (time T3).

<Action effect>
As described above, the target engine speed is set according to the vehicle speed of the vehicle 1 and the accelerator opening. Then, normally, the gear ratio of the continuously variable transmission 4 is set to a gear ratio corresponding to the target engine rotation speed.

Apart from the shift lever 35 operated to select the shift range of the continuously variable transmission 4, the shift lever 37 is operably provided between the off position and the on position. When the shift lever 37 is operated, the gear ratio of the continuously variable transmission 4 is increased by a predetermined correction value from the gear ratio corresponding to the target engine speed, that is, the gear ratio according to the vehicle speed and the accelerator opening. By increasing the gear ratio by a predetermined amount, the rotation speed of the engine increases, the engine brake acts on the drive system of the vehicle 1, and the vehicle 1 decelerates. Therefore, by operating the shift lever 37 simply and intuitively, the deceleration by the engine brake can be obtained as the driver intends.

Further, the correction value is set to a larger value as the amount of operation from the off position of the shift lever 37 is larger. As a result, the larger the driver operates the shift lever 37, the larger the gear ratio (shifts to the low side), and the deceleration by the engine brake according to the driver's intention can be obtained.

<Other embodiments>
FIG. 4 is a diagram showing a main part of the configuration of a vehicle 1 equipped with a control device according to another embodiment of the present invention. In FIG. 4, the portions corresponding to the respective parts shown in FIG. 1 are designated by the same reference numerals as those of the respective portions. Further, in the following, the description of the portion with the same reference numeral will be omitted, and only the difference between the configuration shown in FIG. 4 and the configuration shown in FIG. 1 will be described.

In the configuration shown in FIG. 4, the shifting lever 41 is provided in place of the shifting lever 37 shown in FIG. Like the shift lever 37, the shift lever 41 has a ring shape surrounding the steering shaft, and can be operated between the front off position and the rear on position in the axial direction of the steering shaft, and is a momentary operation. However, the stroke is shorter than that of the shift lever 37.

In the configuration shown in FIG. 4, instead of the lever stroke sensor 38 shown in FIG. 1, a momentary type lever switch 42 that outputs a signal according to the off position and the on position of the shift lever 41 is provided. ..

FIG. 5 is a diagram showing an example of time changes in the lever operation amount and the gear ratio of the continuously variable transmission 4.

In the configuration shown in FIG. 4, when the shift lever 41 is operated from the off position to the on position (time T11), a correction value for increasing the gear ratio of the continuously variable transmission 4 is set. The correction value is set so that the correction value linearly increases as the time for which the shift lever 41 is held in the on position is extended. At this time, as shown in FIG. 5, the correction value may be increased n-th order functionally, for example, quadratic function with respect to the passage of time, but is increased linearly in proportion to the passage of time. You may.

After that, the hydraulic circuit of the continuously variable transmission 4 is controlled, and the gear ratio of the continuously variable transmission 4 is increased by a correction value from the target gear ratio in the above-mentioned shift control (time T11-T12). Since the rotation speed of the engine 2 increases due to the increase in the gear ratio, the engine brake acts on the drive system of the vehicle 1, and the vehicle 1 is decelerated by the engine brake.

Since the correction value increases as the holding time of the shift lever 37 in the on position increases, the engine brake can be strengthened by the driver keeping the shift lever 37 in the on position. Therefore, when the deceleration of the vehicle 1 due to the engine brake is smaller than the deceleration desired by the driver, the driver desires by holding the shift lever 37 in the on position until the desired deceleration is obtained. You can get the deceleration of.

When the operation of the shift lever 37 is released (time T12), the correction value is reduced with the passage of time thereafter. As the correction value is reduced, the gear ratio of the continuously variable transmission 4 is lowered (time T12-T13), so that the rotation speed of the engine 2 is lowered and the engine brake is weakened. When the correction value is reduced to 0, the gear ratio of the continuously variable transmission 4 becomes the target gear ratio in the above-mentioned shift control, and the engine braking action by the operation of the shift lever 37 disappears (time T13).

Even with the configuration shown in FIG. 4, the deceleration by the engine brake can be obtained according to the driver's intention by the simple and intuitive operation of the shift lever 41.

<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 configuration shown in FIG. 4, the lever switch 42 is turned on once the shift lever 41 is operated from the off position to the on position, and the on state is maintained even when the operation of the shift lever 41 is released. It may be a so-called alternate operation type switch.

In this case, even if the shift lever 41 is released from the operation of the shift lever 41 and the shift lever 41 returns from the on position to the off position while the lever switch 42 is in the ON state, the shift lever 41 is positioned in the ON position in the ECU 31. It is judged that there is. Therefore, it is not necessary to keep the shift lever 41 in the on position, so that the burden of operation by the driver can be reduced.

Further, the speed change levers 37 and 41 are not limited to the ring shape, but may be a paddle shape or a rod shape.

Although the configuration in which the engine control logic and the CVT control logic are incorporated in one ECU 31 has been taken up, the engine control logic and the CVT control logic may be provided as separate ECUs.

Further, although the continuously variable transmission 4 has been taken up, the control device according to the present invention can also be used for a power split type continuously variable transmission. The power split type continuously variable transmission is equipped with a belt-type continuously variable transmission mechanism that shifts power steplessly by changing the gear ratio and a constant transmission mechanism that shifts power at a constant gear ratio, and power of a drive source. Is a transmission that can be transmitted by dividing it into two systems.

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

1: Vehicle 4: Continuously variable transmission 31: ECU (control device, speed change means, changing means)
35: Shift lever (first operating member)
37, 41: Shift lever (second operating member)

Claims (1)

A control device for controlling a continuously variable transmission, which is used in a vehicle equipped with a continuously variable transmission capable of continuously shifting the power from the engine.
A speed change means for setting a target value according to the vehicle speed and the accelerator opening of the vehicle and setting the gear ratio of the continuously variable transmission to a gear ratio corresponding to the target value.
A second operating member that is provided separately from the first operating member that is operated to select the shift range of the continuously variable transmission and that is operated between the off position and the on position.
Even if the second operating member is operated from the off position to the on position, the operation is released, and the second operating member returns from the on position to the off position, the gear ratio corresponding to the target value is obtained. continuously and a changing means for changing the increasing atmospheric to so that the control device.

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