JP7033216B2 - Belt type continuously variable transmission - Google Patents

Description

The present invention relates to a belt-type continuously variable transmission that controls the hydraulic pressure of the secondary pulley by feedback control.

According to Patent Document 1, in a hydraulic control device for a belt-type continuously variable transmission for a vehicle, a target secondary pressure is calculated based on an input torque and a target gear ratio, and a secondary pressure control actuator is provided so that a target secondary pressure is generated. By driving, the occurrence of belt slip is avoided.

However, when setting the target secondary pressure and performing feedback control so that the actual secondary pressure becomes the target secondary pressure, using integral control is effective in eliminating the steady deviation, but the target secondary pressure changes. In this situation, the actual secondary pressure overshoots the target secondary pressure, making it difficult to stabilize the shift control. This tendency becomes more remarkable as the feedback gain is increased in order to improve the responsiveness of the shift control. Here, in order to improve the stability of the shift control, it is conceivable to suppress the feedback gain as much as possible, but when the feedback gain becomes small, the responsiveness of the shift control deteriorates, and the target gear ratio and the actual gear ratio become There is a problem that the deviation becomes large. Further, if the feedback gain is changed during shift control, there is a problem that the shift control system becomes unstable.

Japanese Unexamined Patent Publication No. 11-12267

The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a belt-type continuously variable transmission capable of ensuring the stability of shift control.

In the control device for the belt-type continuously variable transmission of the present invention, a primary pulley, a secondary pulley, a belt wound around both pulleys, a hydraulic control unit that supplies control hydraulic pressure to the primary pulley and the secondary pulley, and a hydraulic control unit. It is a belt type continuously variable transmission equipped with
The target secondary pressure of the secondary pulley is calculated based on the input torque to the belt-type continuously variable transmission, and feedback control by integral control is performed based on the deviation between the target secondary pressure and the actual secondary pressure.
Based on the balanced thrust ratio map, calculate the balanced thrust ratio, which is the ratio between the primary pressure and the secondary pressure to balance the gear ratio to a constant value.
The secondary pressure compensation value is calculated based on the deviation between the target secondary pressure and the actual secondary pressure.
The target gear ratio is calculated based on the running condition, and the differential thrust command value of the primary pulley is calculated based on the deviation between the actual gear ratio and the target gear ratio.
The target primary pressure of the primary pulley is obtained by adding the value obtained by multiplying the target secondary pressure by the balance thrust ratio, the secondary compensating hydraulic pressure obtained by multiplying the secondary pressure compensation value by the balance thrust ratio, and the differential thrust command value. Was calculated, and the actual primary pressure was controlled to be the target primary pressure.

Therefore, the deviation between the target secondary pressure and the actual secondary pressure generated in the secondary pulley is regarded as a disturbance, and the stability of the shift control can be ensured by compensating on the primary pulley side.

It is a system diagram of the vehicle provided with the belt type continuously variable transmission of Embodiment 1. FIG. It is a control block diagram which shows the shift control process in the transmission controller of Embodiment 1. FIG. It is a balance thrust ratio map used for the shift control of the belt type continuously variable transmission of Embodiment 1. FIG. It is a control block diagram which shows the structure of the secondary pressure compensation part of Embodiment 1. FIG. It is a flowchart which shows the secondary pressure compensation processing of Embodiment 1. It is a time chart which shows the relationship between the deviation of Embodiment 1 and disturbance.

[Embodiment 1]
FIG. 1 is a system diagram of a vehicle provided with a belt-type continuously variable transmission according to the first embodiment. The vehicle of the first embodiment has an engine 1 which is an internal combustion engine and a belt-type continuously variable transmission CVT, and transmits a driving force to the drive wheels 8 via a differential gear 7. The belt-type stepless transmission CVT rotates integrally with the transmission input shaft 2 connected to the crank shaft of the engine 1, the primary pulley 3 that rotates integrally with the transmission input shaft 2, and the transmission output shaft 6. It has a secondary pulley 5 and a belt 4 that is wound between the primary pulley 3 and the secondary pulley 5 to transmit power.

The primary pulley 3 has a fixed sheave 3a formed integrally with the transmission input shaft 2 and a movable sheave 3b that can move on the axis of the transmission input shaft 2. A primary pressure chamber 3b1 is provided in the movable sheave 3b, and a pressing force is generated between the fixed sheave 3a and the movable sheave 3b by the hydraulic pressure supplied to the primary pressure chamber 3b1 to narrow the belt 4. Similarly, the secondary pulley 5 has a fixed sheave 5a integrally formed with the transmission output shaft 6 and a movable sheave 5b that can move on the axis of the transmission output shaft 6. A secondary pressure chamber 5b1 is provided in the movable sheave 5b, and a pressing force is generated between the fixed sheave 5a and the movable sheave 5b by the hydraulic pressure supplied to the secondary pressure chamber 5b1 to sandwich the belt 4.

The engine controller 10 controls the engine speed and the engine torque TENG (hereinafter, also referred to as input torque Tin) by controlling the operating state (fuel injection amount, ignition timing, etc.) of the engine 1. Further, in the engine controller 10, a required torque calculation unit that calculates the driver's required torque TD based on the accelerator opening signal APO detected by the accelerator opening sensor 21 and the vehicle speed signal VSP detected by the vehicle speed sensor 22. It has a 10a and an engine torque calculation unit 10b that calculates an input torque Tin transmitted to the transmission input shaft 2.

In the transmission controller 20, the primary pressure and the secondary pressure according to the traveling state are calculated, and the control signal is output to the control valve unit 30. Details of the transmission controller 20 will be described later.

The control valve unit 30 uses an oil pump 9 chain-driven on the transmission input shaft 2 as a hydraulic pressure source, and regulates each hydraulic pressure based on a control signal transmitted from the transmission controller 20. Then, the primary pressure and the secondary pressure are supplied to the primary pressure chamber 3b1 and the secondary pressure chamber 5b1, respectively, and the shift control is executed. The control valve unit 30 includes a primary pressure sensor 31 that detects the primary pressure (hydraulic pressure supplied to the primary pressure chamber 3b1), a secondary pressure sensor 32 that detects the secondary pressure (hydraulic pressure supplied to the secondary pressure chamber 5b1), and the secondary pressure sensor 32. Has. Further, the primary pulley 3 has a primary rotation speed sensor 23 that detects the rotation speed of the primary pulley 3. The secondary pulley 5 has a secondary rotation speed sensor 24 that detects the rotation speed of the secondary pulley 5. The value detected by each sensor is output to the transmission controller 20.

FIG. 2 is a control block diagram showing a shift control process in the transmission controller of the first embodiment.
The target gear ratio calculation unit 201 calculates the target gear ratio Ip * based on the accelerator opening signal APO and the vehicle speed signal VSP. This target gear ratio Ip * is performed based on the gear shifting characteristics preset so that the engine 1 achieves the optimum fuel consumption.
The secondary pressure calculation unit 202 calculates the target secondary pressure Psec * that secures the necessary clamping force in the secondary pulley 5 based on the input torque Tin.

In the balance thrust ratio calculation unit 203, the gear ratio Ip calculated based on the primary rotation speed Npri detected by the primary rotation speed sensor 23 and the secondary rotation speed Nsec detected by the secondary rotation speed sensor 24, and the required torque TD The balance thrust ratio Kbl is calculated from the preset balance thrust ratio map based on the torque ratio Qt, which is the ratio of the input torque Tin set based on. The balanced thrust ratio Kbl is the ratio of the primary thrust and the secondary thrust when achieving and balancing (maintaining the gear ratio), which is a certain torque ratio.

FIG. 3 is a balanced thrust ratio map used for shift control of the belt-type continuously variable transmission according to the first embodiment. In this balanced thrust ratio map, the characteristics of the balanced thrust ratio Kbl with respect to the torque ratio are set at each gear ratio. The balance thrust ratio calculation unit 203 selects the characteristic corresponding to the current gear ratio Ip from the balance thrust ratio map, and calculates the balance thrust ratio Kbl corresponding to the torque ratio Qt in the selected characteristic.

The balance thrust calculation unit 204 multiplies the target secondary pressure Psec * by the balance thrust ratio Kbl to calculate the balance thrust equivalent hydraulic pressure Pbl. That is, the pulley thrust is obtained by multiplying the secondary pressure Psec and the primary pressure Ppri by the specifications of the belt-type continuously variable transmission CVT such as the pulley pressure receiving area. Since these specifications are fixed values and the control target is hydraulic pressure, in the first embodiment, the calculation is based on hydraulic pressure instead of thrust. Further, the balance thrust ratio Kbl is multiplied by the secondary pressure compensation value Pprih calculated by the secondary pressure compensation unit 300, which will be described later, to calculate the secondary compensation hydraulic pressure Pb2. Then, the balance thrust equivalent hydraulic pressure Pb1 and the secondary compensation hydraulic pressure Pb2 are added.

The gear ratio control unit 205 calculates the feedback hydraulic pressure based on the deviation between the target gear ratio Ip * and the actual gear ratio Ip. For example, the hydraulic pressure (hereinafter referred to as feedback pressure Pfb) to be added to or subtracted from the current primary pressure Ppri by PI control or PID control is output.
In the primary pressure calculation unit 206, the balance thrust equivalent hydraulic pressure Pbl, the secondary compensation hydraulic pressure Pb2, and the feedback pressure Pfb are added to calculate the primary pressure command value Ppri1.
The primary side current conversion unit 207 converts the primary solenoid current command value according to the primary pressure command value Ppri1.
The primary solenoid current control unit 208 performs servo control so that the primary solenoid current becomes the primary solenoid current command value.

The secondary pressure integral control unit 209 calculates the secondary pressure command value Psec1 by integral control based on the deviation ΔPsec between the target secondary pressure Psec * and the current actual secondary pressure Psec.
The secondary side current conversion unit 210 converts the secondary solenoid current command value according to the secondary pressure command value Psec1.
The secondary solenoid current control unit 211 performs servo control so that the secondary solenoid current becomes the secondary solenoid current command value.
The primary solenoid 212 energizes the solenoid valve that regulates the primary pressure Ppri. The current sensor provided in the primary solenoid 212 outputs a current value to the primary solenoid current control unit 208.
The primary pressure system 213 outputs the primary pressure Ppri regulated by the primary solenoid 212. The primary pressure Ppri is detected by the primary pressure sensor 31.
The secondary solenoid 214 energizes the solenoid valve that regulates the secondary pressure Psec. The current sensor provided in the secondary solenoid 214 outputs a current value to the secondary solenoid current control unit 211.
The secondary pressure system 215 outputs the secondary pressure Psec adjusted by the secondary solenoid 214. The secondary pressure Psec is detected by the secondary pressure sensor 32.

The secondary pressure compensation unit 300 calculates the secondary compensation hydraulic pressure Pb2 based on the deviation between the target secondary pressure Psec * and the current actual secondary pressure Psec, and outputs Pb2 as the secondary compensation hydraulic pressure if certain conditions are met. However, if the predetermined condition is not satisfied, the output of the secondary compensation hydraulic pressure Pb2 is prohibited, and 0 is output instead.

FIG. 4 is a control block diagram showing the configuration of the secondary pressure compensation unit according to the first embodiment. The divergence detection unit 301 detects whether or not the primary pressure command value Ppri1 which is the final command signal is diverging. Here, the divergence of the command signal is detected based on whether or not the state in which the frequency is equal to or higher than the predetermined value and the amplitude is equal to or higher than the predetermined value continues for a predetermined time. The oil vibration detection unit 302 first converts the voltage signal detected by the hydraulic sensor such as the primary pressure sensor 31 or the secondary pressure sensor 32 into a hydraulic signal, and performs a bandpass filter processing to obtain a DC component (variable component according to the control command). Is removed and only the vibration component is extracted. Then, the amplitude of the vibration component is calculated, and when the state in which the amplitude of the hydraulic signal is equal to or higher than the predetermined amplitude continues for a predetermined time or longer, it is determined that oil vibration has occurred. On the other hand, if the state in which the amplitude is less than the predetermined amplitude continues for a predetermined time or longer from the state in which it is determined that the oil shake has occurred, it is determined that the oil shake has not occurred.

In the disturbance estimation unit 303, the deviation ΔPsec between the target secondary pressure Psec * and the current actual secondary pressure Psec is regarded as a disturbance, and ΔPsec is calculated as the secondary pressure compensation value Pprih. FIG. 6 is a time chart showing the relationship between the deviation ΔPsec of the first embodiment and the disturbance. For example, when the driver depresses the accelerator pedal greatly and the kickdown shift is performed, the input torque Tin increases and the target gear ratio Ip * is also greatly changed to the low side. When the target secondary pressure Psec * rises at once with these changes, the actual secondary pressure Psec also rises to follow it. At this time, the integration component is accumulated in the feedback control system by the integral control due to the follow-up delay of the actual secondary pressure Psec, and the actual secondary pressure Psec is likely to overshoot with respect to the target secondary pressure Psec *. If the feedback gain is set large in order to avoid the accumulation of the integral component, the overshoot becomes larger and the stability of the control is lowered. Further, if the feedback gain is reduced, the followability deteriorates.

Therefore, in the first embodiment, the deviation ΔPsec is regarded as a disturbance, and the disturbance is compensated on the primary pulley side to ensure the stability of the shift control without imposing a burden on the control on the secondary pulley side. .. Specifically, the deviation ΔPsec is calculated as the secondary pressure compensation value Pprih. Then, the secondary pressure compensation value Pprih is multiplied by the balance thrust ratio Kb1 to calculate the secondary compensation hydraulic pressure Pb2. Next, when calculating the primary pressure command value Ppri1, the secondary compensating hydraulic pressure Pb2 is added to the balance thrust equivalent hydraulic pressure Pb1 and the feedback pressure Pfb. As a result, the disturbance generated on the secondary pulley side is dealt with in advance of the change in the gear ratio on the primary pulley side, so that the shift control can be stabilized. In other words, when calculating the primary pressure command value Ppri1 without going through the flow that the actual secondary pressure Psec changes due to the deviation ΔPsec and the gear ratio changes, and the primary pressure command value Ppri1 changes in response to this. By adding the secondary compensating hydraulic pressure Pb2 to the balance thrust equivalent hydraulic pressure Pb1 and the feedback pressure Pfb, it is possible to stabilize the shift control prior to the change in the gear ratio due to the change in the actual secondary pressure Psec.

FIG. 5 is a flowchart showing the secondary pressure compensation process of the first embodiment.
In step S1, the secondary pressure compensation value Pprih is calculated based on the secondary pressure deviation ΔPsec.
In step S2, the gear ratio deviation is calculated. The gear ratio deviation is a value obtained by subtracting the actual gear ratio Ip from the target gear ratio Ip *. If the gear ratio deviation is positive, it indicates a state in which it is necessary to shift to the lower side, and if the gear ratio deviation is negative, it indicates a state in which it is necessary to shift to a higher gear side.

In step S3, the fail experience information is set from the fail conditions. The fail condition indicates that the divergence detection unit 301 has detected the divergence or the oil vibration detection unit 302 has detected the oil vibration (corresponding to the second condition). If you are experiencing either one, set the fail experience information.

In step S4, the fail experience information is cleared from the return conditions. The return condition indicates that the divergence is not detected, the oil vibration is not detected, or the ignition is turned off.

In step S5, it is determined whether or not the actual secondary pressure Psec is in the region where overshoot (also referred to as O / S) is likely to occur with respect to the target secondary pressure Psec * in shift control (corresponding to the first condition). In the area where overshoot is likely to occur, proceed to step S6, and in other cases, proceed to step S9 to prohibit the addition of the secondary compensating hydraulic pressure Pb2. Here, in the region where overshoot is likely to occur, the actual gear ratio Ip is on the lower side than the predetermined gear ratio, the actual gear ratio Ip is on the lower side than the target gear ratio Ip *, and the input torque Tin is. Indicates a case larger than a predetermined value. That is, since the change in the actual secondary pressure Psec becomes large, it is considered that the integral component of the feedback control is accumulated when the actual secondary pressure Psec reaches the target secondary pressure Psec *.

In step S6, it is determined whether or not the secondary compensating hydraulic pressure Pb2 acts in the direction of reducing the deviation calculated in step S2. Willingly prohibit the addition of secondary compensation hydraulic pressure Pb2. That is, when the gear ratio deviation is positive, addition is permitted only when the secondary compensation hydraulic pressure Pb2 is positive, and when it is negative, addition is prohibited. On the other hand, when the gear ratio deviation is negative, addition is permitted only when the secondary compensation hydraulic pressure Pb2 is negative, and when it is positive, addition is prohibited.

In step S7, it is determined whether or not the user has experienced a fail, and if the fail is experienced, the addition of the secondary compensating hydraulic pressure Pb2 may promote the fail on the primary pulley side. Proceed to S9 and prohibit the addition of secondary compensation hydraulic pressure Pb2. On the other hand, if the fail experience information is cleared, the process proceeds to step S8.
In step S8, the secondary compensating hydraulic pressure Pb2 is added when the primary pressure command value Ppri1 is calculated.

As described above, in the first embodiment, the following effects can be obtained.
(1) A primary pulley 3, a secondary pulley 5, a belt 4 wound around both pulleys, a control valve unit 30 (hydraulic control unit) that supplies control hydraulic pressure to the primary pulley 3 and the secondary pulley 5. It is a belt type continuously variable transmission CVT equipped with
The target secondary pressure Psec * of the secondary pulley 5 is calculated based on the input torque Tin to the belt-type continuously variable transmission CVT, and feedback by integral control is performed based on the deviation between the target secondary pressure Psec * and the actual secondary pressure Psec. Take control and
Based on the balance thrust ratio map, calculate the balance thrust ratio Kb1 which is the ratio of the primary pressure Ppri and the secondary pressure Psec to balance the gear ratio to a constant value.
Calculate the secondary pressure compensation value Pprih based on the deviation between the target secondary pressure Psec * and the actual secondary pressure Psec.
The target gear ratio Ip * is calculated based on the driving condition, and the differential thrust command value of the primary pulley 3 is calculated based on the deviation between the actual gear ratio Ip and the target gear ratio Ip *.
The balanced thrust equivalent hydraulic pressure Pb1 obtained by multiplying the target secondary pressure by the balanced thrust ratio Kb1, the secondary compensated hydraulic pressure Pb2 obtained by multiplying the secondary pressure compensation value Pprih by the balanced thrust ratio Kb1, and the feedback pressure Pfb (differential thrust command value). By adding, the target primary pressure Ppri * of the primary pulley 3 is calculated, and the actual primary pressure Ppri is controlled to be the target primary pressure Ppri *.
Therefore, the deviation between the target secondary pressure Psec * and the actual secondary pressure Psec generated in the secondary pulley 5 is regarded as a disturbance, and the stability of the shift control can be ensured by compensating on the primary pulley side.

(2) When the actual gear ratio Ip is on the low side of the target gear ratio Ip *, the secondary compensating hydraulic pressure Pb2 is added only when shifting to the high side by adding the secondary compensating hydraulic pressure Pb2, and the actual gear ratio Ip is the target. When the gear ratio is higher than Ip *, the secondary compensating hydraulic pressure Pb2 is added and the secondary compensating hydraulic pressure Pb2 is added only when shifting to the low side.
As a result, the secondary pressure compensation processing can be performed only when the deviation between the target gear ratio Ip * and the actual gear ratio Ip converges by adding the secondary compensating hydraulic pressure Pb2, and the stability of shifting control can be ensured. ..

(3) The first condition that the target gear ratio Ip * is on the lower side than the predetermined gear ratio, the actual gear ratio Ip is on the lower side than the target gear ratio Ip *, and the input torque Tin is equal to or more than the predetermined value. When is satisfied, the secondary compensating hydraulic pressure Pb2 is added, and in other cases, the addition of the secondary compensating hydraulic pressure Pb2 is prohibited.
Therefore, in the feedback control of the secondary pulley 5, it can be operated in the region where the accumulation of the integral component is predicted, and in the region where the accumulation of the integral component is not a concern, the feedback control as usual is performed to stabilize the shift control. Can be secured.

(4) When the second condition indicating the divergence of the target primary pressure Ppri * or the oil vibration in the control valve unit 30 is satisfied, the addition of the secondary compensation hydraulic pressure Pb2 is prohibited.
Therefore, when there is a possibility that the control system becomes unstable, the stability of the shift control can be ensured by avoiding the secondary pressure compensation process.

(5) If the second condition is not satisfied after the prohibition of the addition of the secondary compensating hydraulic pressure Pb2, the prohibition of the addition of the secondary compensating hydraulic pressure Pb2 is lifted.
Therefore, when the stability of the control system is confirmed, the stability of the shift control can be ensured by restarting the secondary pressure compensation process.

[Other Examples]
Although the embodiment for carrying out the present invention has been described above based on the examples, the specific configuration of the present invention is not limited to the configuration shown in the examples and does not deviate from the gist of the invention. Even if there is a design change or the like, it is included in the present invention. Although the vehicle not provided with the torque converter has been described in the first embodiment, the vehicle may be provided with the torque converter. Further, although the configuration including only the engine which is an internal combustion engine as the power source is exemplified, it may be applied to a hybrid vehicle or the like equipped with an electric motor.

Claims (6)

A belt-type continuously variable transmission including a primary pulley, a secondary pulley, a belt wound around both pulleys, and a hydraulic control unit for supplying control hydraulic pressure to the primary pulley and the secondary pulley.
The target secondary pressure of the secondary pulley is calculated based on the input torque to the belt-type continuously variable transmission, and feedback control by integral control is performed based on the deviation between the target secondary pressure and the actual secondary pressure.
Based on the balanced thrust ratio map, calculate the balanced thrust ratio, which is the ratio between the primary pressure and the secondary pressure to balance the gear ratio to a constant value.
The secondary pressure compensation value is calculated based on the deviation between the target secondary pressure and the actual secondary pressure.
The target gear ratio is calculated based on the running condition, and the differential thrust command value of the primary pulley is calculated based on the deviation between the actual gear ratio and the target gear ratio.
The target primary pressure of the primary pulley is obtained by adding the value obtained by multiplying the target secondary pressure by the balance thrust ratio, the secondary compensating hydraulic pressure obtained by multiplying the secondary pressure compensation value by the balance thrust ratio, and the differential thrust command value. Is calculated and the actual primary pressure is controlled to be the target primary pressure.
Belt type continuously variable transmission. In the belt type continuously variable transmission according to claim 1.
When the actual gear ratio is on the low side of the target gear ratio, the secondary compensating hydraulic pressure is added only when shifting to the high side by adding the secondary pressure compensation value.
When the actual gear ratio is higher than the target gear ratio, the secondary compensating hydraulic pressure is added only when shifting to the low side by adding the secondary compensating hydraulic pressure.
Belt type continuously variable transmission. In the belt type continuously variable transmission according to claim 1 or 2.
When the first condition is satisfied, the target gear ratio is lower than the predetermined gear ratio, the actual gear ratio is lower than the target gear ratio, and the input torque is equal to or higher than the predetermined value. Add the secondary compensating hydraulic pressure, otherwise prohibit the addition of the secondary compensating hydraulic pressure,
Belt type continuously variable transmission. In the belt type continuously variable transmission according to any one of claims 1 to 3.
When the second condition indicating the divergence of the target primary pressure or the oil vibration in the hydraulic pressure control unit is satisfied, the addition of the secondary compensating hydraulic pressure is prohibited.
Belt type continuously variable transmission. In the belt type continuously variable transmission according to claim 4.
If the second condition is not satisfied after the prohibition of the addition of the secondary compensating hydraulic pressure, the prohibition of the addition of the secondary compensating hydraulic pressure is lifted.
Belt type continuously variable transmission. In the belt type continuously variable transmission according to claim 3.
When the second condition indicating the divergence of the target primary pressure or the oil vibration in the hydraulic pressure control unit is satisfied, the addition of the secondary compensating hydraulic pressure is prohibited.
If the first condition is not satisfied after the prohibition of the addition of the secondary compensating hydraulic pressure, the prohibition of the addition of the secondary compensating hydraulic pressure is lifted.
Belt type continuously variable transmission.

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