JP2011002008A - Hydraulic control device of continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the durability of a continuously variable transmission by suppressing control pressure overshoot generated at the time of ignition OFF.SOLUTION: A hydraulic control device 11 of the continuously variable transmission consisting of a pair of variable pulley connected through belt is equipped with a detecting means for detecting a condition that an ignition key 18 has been turned OFF, wherein an actuator is driven continuously by a predetermined time after the ignition key 18 has been detected in OFF, and then the actuator is stopped with a lapse of the predetermined time.

Description

  The present invention relates to a hydraulic control device for a continuously variable transmission mounted on a vehicle.

  2. Description of the Related Art Conventionally, V-belt type continuously variable transmissions are known as vehicle transmissions. As shown in FIG. 2, a primary pulley 22 and a secondary pulley 23 that variably control the groove width based on hydraulic pressure are connected by a V-belt 21. 24 and 25 are provided, and by changing the groove width according to the hydraulic pressure supplied to them, the gear ratio is continuously changed and the clamping pressure of the V belt 21 is controlled. Further, the driving force is transmitted according to the frictional force between the primary pulley 22 and the secondary pulley 23 and the V-belt 21.

  The transmission control valves 33 and 34 are supplied with a line pressure obtained by adjusting the hydraulic pressure from the oil pump 31 driven by the rotational motion generated by the engine by the line pressure control valve 32. The shift control valves 33 and 34 further adjust the line pressure to supply the primary pressure to the hydraulic chamber 24 and the secondary pressure to the hydraulic chamber 25, respectively.

  Each control valve is provided with a solenoid valve that controls opening and closing by electromagnetic force, and the control pressure such as line pressure, primary pressure, and secondary pressure is adjusted by controlling the voltage supplied to the solenoid valve.

  The hydraulic control device 11 is electrically connected to each solenoid valve, and performs a PWM (Pulse Width Modulation) control that changes the ratio between the ON time and the OFF time by turning on and off the current supply at a high speed. Control the amount of current.

Japanese Patent Laid-Open No. 11-82725

  The conventional continuously variable transmission has a system configuration in which the control of the line pressure or the like is started when the ignition key is turned on, and the control is ended when the ignition key is turned off. Specifically, the electronic circuit configuration is such that the current supply to the solenoid valve is turned on and off at the timing of ignition key ON / OFF. As the solenoid valve, a so-called normal-high valve that is fully open when the current is interrupted and generates hydraulic pressure has been adopted. This realizes fail-safe that avoids a situation where the hydraulic pressure supply is stopped when an unexpected current interruption occurs due to an electronic circuit failure or the like.

  However, in the system configuration described above, when the ignition key is turned OFF, the solenoid valve is fully opened, but the engine continues to rotate for a while after the fuel is shut off, so that the hydraulic pressure is continuously supplied from the oil pump. If the solenoid valve is in the fully closed state or close to it before the ignition key is turned off, the control pressure overshoot occurs as shown in Fig. 5 between the ignition key and the oil pump stop state. This causes an impact (oil hammer). In recent years, transmission members have been reduced in weight and thickness, and impact due to control pressure overshoot has adversely affected the durability of the transmission.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to suppress the control pressure overshoot that occurs when the ignition is turned off to ensure the durability of the continuously variable transmission.

  In order to solve the above problems, the present invention is a hydraulic control device for a continuously variable transmission comprising a pair of variable pulleys connected via a belt, comprising a pair of variable pulleys connected via a belt. A continuously variable transmission, first and second cylinder chambers adjacent to these variable pulleys and capable of changing the groove width, hydraulic supply means for supplying hydraulic pressure thereto, and hydraulic pressure from the hydraulic supply means is predetermined. A line pressure supply means for adjusting the line pressure, and two shift control valves that receive the supply of the line pressure and are driven by an actuator to supply hydraulic pressure based on the line pressure to the first cylinder chamber and the second cylinder chamber, respectively. And a control means for driving the actuator according to the driving state of the vehicle and continuously variably controlling the speed ratio according to the hydraulic pressure from the speed change control valve. The control device includes detection means for detecting that the ignition key is turned off, and continues to drive the actuator for a predetermined time after detecting that the ignition key is turned off. After the predetermined time has elapsed, the actuator is driven. It is characterized by stopping.

  In the hydraulic control device for the continuously variable transmission, the drive of the solenoid valve is stopped when the hydraulic pressure supplied from the hydraulic pressure supply means falls below a predetermined pressure after detecting that the ignition key is turned off. You may comprise so that it may do.

  Further, the hydraulic control device for the continuously variable transmission may be configured to stop the driving of the solenoid valve when the hydraulic pressure supply unit stops after detecting that the ignition key is turned off. .

  The continuously variable transmission detects a sudden drop in the control pressure in parallel with the solenoid valve control, and detects this as a failure.However, after the ignition is turned off, the control pressure drop detection process is performed. It stops, and it is prevented that the original hydraulic pressure drop of the control pressure is erroneously determined as a failure.

  When the first invention is applied, the hydraulic control device continues the solenoid control for a predetermined time after the ignition key is turned OFF, and then stops the driving of the solenoid. Even after the ignition is turned off, the engine continues to rotate due to inertia, but after a predetermined time has elapsed, the rotational speed has decreased, and the hydraulic pressure generated by the oil pump has also decreased. Since the valve is fully opened by stopping the solenoid drive at this time, it is possible to suppress the overshoot of the control pressure and ensure the durability of the continuously variable transmission. This is shown in FIG.

  When the second invention is applied, after the ignition key is turned OFF, the hydraulic control device continues the solenoid control until the original hydraulic pressure of the control pressure generated by the oil pump falls below a predetermined value, and then stops driving the solenoid. To do. Thereby, the same effect as that of the first invention is obtained. This is shown in FIG.

  When the third invention is applied, the hydraulic control device continues the solenoid control until the operation of the oil pump stops after the ignition key is turned OFF, and then stops the driving of the solenoid. Thereby, the same effect as that of the first invention is obtained. This is shown in FIG.

The schematic diagram of the hydraulic control device in the present invention. The system block diagram of a V belt type continuously variable transmission. The operation | movement schematic diagram of a three-way linear solenoid valve. The operation | movement schematic diagram of a three-way linear solenoid valve. The time chart which shows the control oil pressure change at the time of IGN key OFF in a prior art. The time chart which shows the control oil pressure change at the time of IGN key OFF in 1st Example of this invention. The time chart which shows the control oil pressure change at the time of IGN key OFF in 2nd Example of this invention. The time chart which shows the control oil pressure change at the time of IGN key OFF in 3rd Example of this invention. PWM control block diagram. The time chart which shows operation | movement of the hydraulic control apparatus from IGN key ON to solenoid drive start in this invention. The time chart which shows operation | movement of the hydraulic control apparatus from the IGN key OFF in this invention until it stops control of a continuously variable transmission. The schematic diagram of the hydraulic control apparatus in a prior art. The time chart which shows operation | movement of the hydraulic control apparatus until it stops control of a continuously variable transmission from the IGN key OFF in a prior art.

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

  In a continuously variable transmission to which the present invention is applied, a three-way linear solenoid valve is used as a line pressure control valve and a shift control valve. FIG. 3 and FIG. 4 show operation outline diagrams of the three-way linear solenoid valve.

  The three-way linear solenoid valve 41 has a spool 42 and is normally pressed to the right side by the action of a spring 44. However, when a current flows through the coil 43, it is attracted to the left side by electromagnetic force. Oil is supplied from the oil pump via 51, and becomes a control pressure via 52 depending on the position of the spool 42, or drains via 53. By controlling the current flowing through the coil 43, the position of the spool 42 can be continuously moved correspondingly, and the control pressure is controlled by changing the hydraulic path widths of the 52 and 53 accordingly. Can do.

  FIG. 3 shows a state in which no current flows through the coil 43 and all the oil supplied from 51 passes through 52. At this time, the control pressure becomes maximum.

  FIG. 4 shows a state in which the current flowing through the coil 43 is maximized, the spool 42 is attracted to the leftmost, and all the oil supplied from 51 drains through 53. At this time, the control pressure becomes zero.

  FIG. 1 shows a hydraulic control device and a control circuit for a three-way linear solenoid valve to which the present invention is applied. Reference numeral 11 denotes a hydraulic control device for the continuously variable transmission. The hydraulic control device 11 is supplied with a voltage Vbatt directly connected from the battery power supply 12 and a voltage Vign connected via the ignition key 18. The hydraulic control device 11 controls the voltage supply to the three-way linear solenoid valve 41. Although only one three-way linear solenoid valve is shown in the figure, a configuration in which a plurality of solenoid valves are provided and controlled may be used.

  Next, the contents of the hydraulic control device 11 will be described. The CPU 13 performs arithmetic processing and signal output processing for controlling the continuously variable transmission according to a predetermined program. The voltage regulator 16 receives Vbatt from the terminal g and Vign from the terminal c, and supplies the drive voltage Vcc to the CPU 13. The solenoid power relay IC 14 receives Vbatt from the terminal h and receives a relay drive signal from the CPU 13 from the terminal b. Only when the relay drive signal is in the ON state, there is a function of passing Vbatt, and this is output from the terminal D. The solenoid drive IC 15 receives Vbatt from the terminal d and a solenoid drive signal from the terminal a. The solenoid drive signal is output from the terminal A from the CPU 13 as an ON / OFF signal with a variable duty ratio. The solenoid drive IC 15 turns ON / OFF the solenoid supply voltage from the terminal E to the three-way linear solenoid valve 41 in synchronization with ON / OFF of the solenoid drive signal. The current monitor circuit 17 includes a voltage detection resistor arranged in series with the three-way linear solenoid valve 41, and calculates a voltage value across the resistor. The voltage across the resistor is taken into the CPU 13 from the terminal j. With these circuit configurations, the CPU 13 outputs a solenoid drive signal while performing feedback control between the target current value output to the solenoid valve and the actual current value obtained from the current monitor circuit. This is called PWM (Pulse Width Modulation) control. FIG. 9 is a block diagram showing this PWM control. Although only basic control blocks are shown in FIG. 9, for example, correction control using various parameters such as the ambient temperature of the solenoid valve may be included.

  FIG. 10 is a time chart showing the operation from turning on the ignition key (hereinafter referred to as IGN key) to starting the solenoid driving. When the IGN key is turned on (T101), the voltage regulator 16 starts up the power supply Vcc (T102) and cancels RESET (T103), thereby starting the CPU 13. Thereafter, the CPU 13 starts the operation of the continuously variable transmission control program, turns on the self-shut signal and the relay drive signal (T104, T105), and starts outputting the solenoid drive signal (T106). Since the relay drive signal is in the ON state, a solenoid supply voltage is output from the solenoid drive IC 15 in synchronization with the solenoid drive signal (T107). As a result, the opening and closing of the three-way linear solenoid valve 41 can be controlled.

  FIG. 11 is a time chart showing the operation from the IGN key OFF until the control of the continuously variable transmission is stopped. After turning off the IGN key (T201), the CPU 13 continues outputting the solenoid drive signal for a predetermined delay time. Thereby, the open / close control of the three-way linear solenoid valve 41 can be continued. After the delay time has elapsed, the CPU 13 stops outputting the solenoid drive signal (T202). Since the solenoid supply voltage is also stopped in synchronization with this (T203), the three-way linear solenoid valve 41 is fully opened. As an example, the delay time can be defined in a continuously variable transmission control program. Also, at this time, the oil pump gradually approaches the stop state, so each control pressure such as line pressure decreases, but this is a normal transient state until the control of the continuously variable transmission is stopped. During the delay time, the abnormality determination process for determining that the control pressure drop such as the line pressure is abnormal is stopped.

  Thereafter, the CPU 13 turns off the relay drive signal and the self shut signal (T204, T205), stops the operation of the continuously variable transmission control program, and enters the RESET standby state. The voltage regulator 16 detects the self-shut signal OFF, instructs RESET to the CPU 13 after a predetermined time (T206), and turns off the power supply Vcc (T207).

  Prior to the present invention, the solenoid power supply relay IC 14 was not provided as shown in FIG. 12, and the solenoid drive IC 15 took Vign directly as the drive power supply. Therefore, as shown in the time chart of FIG. 13, the solenoid supply voltage stops at the time of T201 with respect to the OFF operation of the IGN key, so that the delay time cannot be secured and the three-way linear solenoid valve 41 Suddenly it becomes fully open. At this time, a control pressure overshoot as shown in FIG. 5 occurs.

  As described above, when the present invention is applied, the hydraulic pressure control device 11 continues the solenoid control for a predetermined time even after the IGN key is turned OFF, and the oil pump generation hydraulic pressure due to the inertia rotation of the engine is sufficiently reduced. Since the linear solenoid valve 41 is fully opened, the control pressure overshoot can be suppressed.

  As a second embodiment, there is a method including a hydraulic pressure sensor that measures the hydraulic pressure generated by the oil pump 31. After turning off the IGN key, the CPU 13 monitors the hydraulic pressure value from the sensor while continuing to output the solenoid driving signal. When the hydraulic pressure falls below a predetermined value, the CPU 13 stops outputting the solenoid driving signal and stops the three-way linear solenoid. The valve 41 is fully opened.

  As a third embodiment, there is a method including a sensor that can detect the rotational speed of the oil pump 31. After turning off the IGN key, the CPU 13 monitors the rotation speed from the sensor while continuing to output the solenoid drive signal, and determines that the oil pump 31 has stopped when the rotation speed becomes a predetermined value or less. The output of the drive signal is stopped and the three-way linear solenoid valve 41 is fully opened.

11 Hydraulic Control Device 12 Battery Power Supply 13 CPU of Hydraulic Control Device
14 Solenoid power relay IC
15 Solenoid drive IC
16 Voltage regulator 17 Current monitor circuit 18 Ignition key 21 V belt 22 Primary pulley 23 Secondary pulley 24 Primary hydraulic chamber 25 Secondary hydraulic chamber 31 Oil pump 32 Line pressure control valve 33, 34 Shift control valve 41 Three-way linear solenoid valve

Claims (4)

A hydraulic control device for a continuously variable transmission comprising a pair of variable pulleys connected via a belt,
First and second cylinder chambers adjacent to each of these variable pulleys and capable of changing the groove width;
Hydraulic supply means for supplying hydraulic pressure to them;
Line pressure supply means for adjusting the hydraulic pressure from the hydraulic pressure supply means to a predetermined line pressure;
Two shift control valves that receive the supply of the line pressure and are driven by an actuator to supply hydraulic pressure based on the line pressure to the first cylinder chamber and the second cylinder chamber, respectively;
In a hydraulic control device for a continuously variable transmission, comprising a control means for driving the actuator according to a driving state of a vehicle and continuously variably controlling a gear ratio according to a hydraulic pressure from a shift control valve,
It has a detecting means for detecting that the ignition key is turned OFF,
A hydraulic control device for a continuously variable transmission, wherein the actuator is continuously driven for a predetermined time after detecting that the ignition key is turned OFF, and the actuator is stopped after a predetermined time has elapsed.   2. The drive of the actuator is stopped when the hydraulic pressure supplied from the hydraulic pressure supply means becomes a predetermined pressure or less after detecting that the ignition key is turned off. A hydraulic control device for a continuously variable transmission according to claim 1.   2. The hydraulic control of the continuously variable transmission according to claim 1, wherein the actuator is stopped when the hydraulic pressure supply unit stops after detecting that the ignition key is turned off. apparatus.   The continuously variable transmission according to any one of claims 1 to 3, wherein detection of an abnormality associated with a decrease in hydraulic pressure is stopped when the drive of the actuator is continued after detecting that the ignition key is turned off. Hydraulic control device for the machine.

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