JP2007255625A - Hydraulic control device for belt type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a lack of primary pressure in restarting a vehicle after suddenly decelerated and stopped. <P>SOLUTION: When determining that the vehicle is suddenly decelerated and stopped with the operation of a brake (S1), in this hydraulic control device for a belt type continuously variable transmission after feedforward control of a step motor so that the primary pressure exceeds target primary pressure (S6) and then the step motor is feedback controlled so that the primary pressure is equal to the target primary pressure (S11). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydraulic control for a hydraulic control device for a belt-type continuously variable transmission, particularly when it is suddenly decelerated and stopped.

In a vehicle equipped with a belt type continuously variable transmission, when the brake is activated and the vehicle stops, the pulley state is estimated based on the change in the gear ratio, and the hydraulic pressure can be supplied to the primary pulley at the time of restart A technique for controlling a motor is described in Patent Document 1.
Japanese Examined Patent Publication No. 6-45319

  However, when the vehicle suddenly decelerates and stops, the change in the gear ratio is so steep that the estimated value of the pulley state (pulley position, etc.) shifts, making it impossible to send the step motor to the appropriate position. There is sex. As a result, the hydraulic pressure supplied to the primary pulley at the time of re-starting is insufficient, so that a sufficient belt clamping force cannot be obtained and belt slipping may occur.

  An object of the present invention is to prevent a shortage of primary pressure at the time of re-start after a vehicle is suddenly decelerated and stopped.

  The hydraulic control device for a belt-type continuously variable transmission according to the present invention performs the feedforward control of the step motor so that the primary pressure exceeds the target primary pressure when it is determined that the vehicle has suddenly decelerated and stopped. The step motor is feedback-controlled so that becomes equal to the target primary pressure.

  According to the present invention, when it is determined that the vehicle has suddenly decelerated and stopped, the primary pressure becomes equal to the target primary pressure after feed-forward control of the step motor so that the primary pressure exceeds the target primary pressure. In addition, since the step motor is feedback controlled, it is possible to prevent the belt from slipping due to insufficient primary pressure when the vehicle restarts after suddenly decelerating and stopping.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a hydraulic control device for a belt type continuously variable transmission according to this embodiment. The belt type continuously variable transmission 10 includes a primary pulley 11, a secondary pulley 12, a V belt 13, a CVT control unit 20 (hereinafter referred to as “CVTCU”), and a hydraulic control unit 30.

  The primary pulley 11 is an input shaft side pulley that inputs the rotation of the engine 1 to the belt type continuously variable transmission 10. The primary pulley 11 forms a V-shaped pulley groove that is disposed opposite to the fixed conical plate 11b that rotates integrally with the input shaft 11d, and acts on the primary pulley cylinder chamber 11c. And a movable conical plate 11a that can be displaced in the axial direction by hydraulic pressure. The primary pulley 11 is connected to the engine 1 through a torque converter 2 having a forward / reverse switching mechanism 3 and a lock-up clutch, and inputs the rotation of the engine 1. The rotation speed of the primary pulley 11 is detected by a primary pulley rotation speed sensor 26.

  The belt 13 is wound around the primary pulley 11 and the secondary pulley 12, and transmits the rotation of the primary pulley 11 to the secondary pulley 12.

  The secondary pulley 12 outputs the rotation transmitted by the belt 13 to the differential 4. The secondary pulley 12 forms a V-shaped pulley groove so as to be opposed to the fixed conical plate 12b that rotates integrally with the output shaft 12d and the fixed conical plate 12b, and acts on the secondary pulley cylinder chamber 12c. And a movable conical plate 12a that can be displaced in the axial direction according to the hydraulic pressure. The pressure receiving area of the secondary pulley cylinder chamber 12c is set substantially equal to the pressure receiving area of the primary pulley cylinder chamber 11c.

  The secondary pulley 12 is connected to the differential 4 via an idler gear 14 and an idler shaft, and outputs rotation to the differential 4. The rotational speed of the secondary pulley 12 is detected by the secondary pulley rotational speed sensor 27. The vehicle speed can be calculated from the rotational speed of the secondary pulley 12.

  The CVTCU 20 is a signal from the inhibitor switch 23, an accelerator pedal stroke amount sensor 24, an oil temperature sensor 25, a primary pulley rotational speed sensor 26, a secondary pulley rotational speed sensor 27, a brake switch 35, etc., and an input torque from the engine control unit 21. Based on the information, the gear ratio (the value obtained by dividing the rotational speed of the primary pulley 11 by the rotational speed of the secondary pulley 12 or the effective radius of the secondary pulley 12 is referred to the effective speed of the primary pulley 11 by referring to a pre-stored shift line. A value divided by the radius) and a contact friction force are determined, and a command is transmitted to the hydraulic control unit 30 to control the belt type continuously variable transmission 10.

  The hydraulic control unit 30 responds based on a command from the CVTCU 20. The hydraulic control unit 30 supplies hydraulic pressure to the primary pulley 11 and the secondary pulley 12 to reciprocate the movable conical plate 11a and the movable conical plate 12a in the rotation axis direction.

  When the movable conical plate 11a and the movable conical plate 12a move, the pulley groove width changes, and the belt 13 moves on the primary pulley 11 and the secondary pulley 12. As a result, the contact radius of the belt 13 with respect to the primary pulley 11 and the secondary pulley 12 changes, and the gear ratio and the contact friction force of the belt 13 are controlled.

  The rotation of the engine 1 is input to the belt type continuously variable transmission 10 via the torque converter 2 and the forward / reverse switching mechanism 3, and is transmitted from the primary pulley 11 to the differential 4 via the belt 13 and the secondary pulley 12.

  When the accelerator pedal is depressed or shift-changed in the manual mode, the movable conical plate 11a of the primary pulley 11 and the movable conical plate 12a of the secondary pulley 12 are displaced in the axial direction to change the contact radius with the belt 13. Thus, the gear ratio is continuously changed.

  The gear ratio is set by searching the primary rotation speed according to the vehicle speed and the throttle opening based on a map in which a plurality of shift lines indicating the relationship between the vehicle speed and the primary rotation speed are prepared for each throttle opening. Is done.

  FIG. 2 is a conceptual diagram of the hydraulic control unit and the CVTCU.

  The hydraulic control unit 30 includes a regulator valve 31, a shift control valve 32, and a pressure reducing valve 33. The hydraulic control unit 30 controls the hydraulic pressure supplied from the hydraulic pump 34 and supplies it to the primary pulley 11 and the secondary pulley 12.

  The regulator valve 31 includes a solenoid, and regulates the pressure of the oil pumped from the hydraulic pump 34 to a predetermined line pressure according to an operation state according to a command (for example, a duty signal) from the CVTCU 20. It is.

  The shift control valve 32 is a control valve that controls the hydraulic pressure (hereinafter referred to as “primary pressure”) of the primary pulley cylinder chamber 11c to a desired target pressure. The shift control valve 32 is connected to a servo link 50 constituting a mechanical feedback mechanism, is driven by a step motor 40 connected to one end of the servo link 50, and is connected to the other end of the primary link 11 connected to the other end of the servo link 50. The groove width, that is, feedback of the actual gear ratio is received from the movable conical plate 11a. The speed change control valve 32 absorbs and discharges hydraulic pressure to and from the primary pulley cylinder chamber 11c by the displacement of the spool 32a, and adjusts the primary pressure so that the target speed ratio commanded at the drive position of the step motor 40 is achieved. When the shift is completed, the spool 32a is held in the closed position in response to the displacement from the servo link 50.

  The pressure reducing valve 33 includes a solenoid and is a control valve that controls a supply pressure to the secondary pulley cylinder chamber 12c (hereinafter referred to as “secondary pressure”) to a desired target pressure.

  The line pressure supplied from the hydraulic pump 34 and regulated by the regulator valve 31 is supplied to the shift control valve 32 and the pressure reducing valve 33, respectively.

  The gear ratio of the primary pulley 11 and the secondary pulley 12 is controlled by a step motor 40 that is driven in accordance with a gear shift command signal from the CVTCU 20, and the gear ratio of the shift control valve 32 is in accordance with the displacement of the servo link 50 that responds to the step motor 40. The spool 32a is driven, the line pressure supplied to the speed change control valve 32 is adjusted and the primary pressure is supplied to the primary pulley 11, and the groove width is variably controlled and set to a predetermined speed ratio.

  The CVTCU 20 includes a range signal from the inhibitor switch 23, an accelerator pedal stroke amount from the accelerator pedal stroke amount sensor 24, an oil temperature of the belt-type continuously variable transmission 10 from the oil temperature sensor 25, a signal from the brake switch 35, a primary Signals from the pulley speed sensor 26, the secondary pulley speed sensor 27, and the hydraulic pressure sensors 28 and 29 are read to variably control the gear ratio and the contact friction force of the V belt 13. The hydraulic pressure sensor 28 is a sensor that detects a primary pressure applied to the cylinder chamber 11c of the primary pulley 11. The hydraulic sensor 29 is a sensor that detects a secondary pressure applied to the cylinder chamber 12 c of the secondary pulley 12.

  While the vehicle is traveling, the step motor 40 is controlled so as to obtain a desired gear ratio. When the vehicle decelerates and stops, the step motor 40 is controlled so that hydraulic pressure can be supplied to the primary pulley 11 when the vehicle restarts. However, when the vehicle suddenly decelerates and stops, the change in the gear ratio is so steep that the step motor 40 cannot be sent to an appropriate position, and the hydraulic pressure supplied to the primary pulley 11 at the time of restart is insufficient. there's a possibility that. In the present embodiment, control of the step motor 40 when the vehicle suddenly decelerates and stops will be described.

  Hereinafter, the control performed by the CVTCU 20 will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing the control of the hydraulic control device of the belt type continuously variable transmission according to this embodiment. These controls are repeatedly performed every minute time (for example, 10 ms).

  In step S1 (vehicle sudden stop determining means), it is determined whether or not the stationary shift fixing control is being executed. If it is determined that the stationary shift fixing control is being executed, the process proceeds to step S2, and if it is determined not to be performed, the process proceeds to step S13. Here, when the vehicle decelerates and stops, the gear ratio is shifted to the low side as the vehicle speed decreases, and after the vehicle stops, the gear ratio is fixed to prepare for a restart. This control after the vehicle stops is a stationary shift fixed control, and is executed when the throttle opening is zero and the brake switch 35 is on, the deceleration is greater than a predetermined deceleration and the vehicle speed becomes zero. When the opening is not zero, that is, when the vehicle restarts, the control ends. The predetermined deceleration is set to such a value that it can be determined that the vehicle has been stopped by sudden braking. Further, the stop-time shift fixing control may be executed when the vehicle speed is equal to or lower than a predetermined vehicle speed or the primary rotation speed is equal to or lower than a predetermined rotation speed. Note that the stationary shifting fixed control is a control that has been conventionally performed, and a detailed description thereof will be omitted.

  In step S2 (primary pressure detection means), the primary pressure is detected.

  In step S3, it is determined whether or not the FF flag is 0. If the FF flag is 0, the process proceeds to step S4, and if it is 1, the process proceeds to step S8. The FF flag is a flag indicating whether or not feed forward control (hereinafter referred to as “FF control”) is performed during execution of the stationary shift fixed control, and is 0 before performing the FF control. When it becomes 1.

  In step S4 (target primary pressure setting means), a target primary pressure is set. The target primary pressure is, for example, the stroke position of the primary pulley 11 and the hydraulic oil so that the clamping force of the belt 13 by the primary pulley 11 exceeds the maximum value of the clamping force that causes slipping between the primary pulley 11 and the belt 13. It is set based on the temperature.

  In step S5, the FF instruction value for the number of steps is output. The step number FF instruction value is set to a number of steps such that the primary pressure is higher than the target primary pressure so that the primary pressure held by the stationary shift fixed control does not become insufficient with respect to the target primary pressure.

  In step S6, the FF flag is set to 1.

  In step S7 (primary pressure control means), the step motor is feedforward (FF) controlled based on the step number FF instruction value.

  On the other hand, if it is determined in step S3 that the FF flag is 1, the process proceeds to step S8, and the target step number is calculated. The target number of steps is the number of steps necessary to realize the target primary pressure, and is calculated by searching the table of FIG. FIG. 4 is a table showing the relationship between the primary pressure and the number of steps necessary to realize the primary pressure. The higher the target primary pressure, the higher the step number is set to a higher value.

  In step S9, the hydraulic pressure deviation is calculated by subtracting the target primary pressure set in step S4 from the actual primary pressure detected in step S2.

  In step S10, the number of correction steps is calculated based on the hydraulic pressure deviation. The number of correction steps is calculated with reference to the table of FIG. 5, and is set to a lower value as the hydraulic pressure deviation increases.

  In step S11, the FB instruction value for the number of steps is output. The step number FB instruction value is calculated by adding the target step number and the correction step number.

  In step S12 (primary pressure control means), the step motor 40 is feedback controlled (hereinafter referred to as “FB control”) based on the step number FB instruction value.

  On the other hand, if it is determined in step S1 that the stationary shift fixing control is not being executed, the process proceeds to step S13, and the FF flag is set to zero.

  Next, the operation of this embodiment will be described with reference to FIGS. 6 and 7 are time charts showing changes in throttle opening, brake switch signal, gear ratio, step motor instruction value, vehicle speed, and primary pressure. FIG. 6 shows the prior art, and FIG. 7 shows this embodiment. The case where it is applied is shown.

  First, the case of the prior art will be described with reference to FIG. At time t1, the throttle opening is zero, the brake switch is turned on, and when the vehicle decelerates suddenly, the instruction value of the step motor 40 is lowered accordingly, so the primary pressure suddenly drops and the gear ratio becomes Low. It changes suddenly to the side.

  When the vehicle stops at time t2, the step motor instruction value is calculated and output so that the primary pressure becomes the target primary pressure in preparation for the vehicle restart. However, since the gear ratio has changed abruptly due to the sudden deceleration of the vehicle, the calculation of the step motor instruction value becomes inaccurate, and the primary pressure is fixed while being insufficient with respect to the target primary pressure.

  At time t4, when the accelerator pedal is depressed and the throttle opening is turned on, the vehicle starts. At this time, since the primary pressure is insufficient, the belt clamping force is insufficient and belt slippage occurs.

  Next, the case of the present embodiment will be described with reference to FIG. Note that a dotted line portion in the figure indicates a portion different from the prior art in the present embodiment. At time t1, the throttle opening is zero, the brake switch is turned on, and when the vehicle decelerates suddenly, the instruction value of the step motor 40 is lowered accordingly, so the primary pressure suddenly drops and the gear ratio becomes Low. It changes suddenly to the side.

  When the vehicle stops at time t2, the step number FF instruction value is output in preparation for the vehicle re-starting, and the primary pressure exceeds the target primary pressure. Subsequently, after time t3, the primary pressure is held at the target primary pressure by feedback control of the step motor 40.

  At time t4, when the accelerator pedal is depressed and the throttle opening is turned on, the vehicle starts. At this time, the primary pressure is substantially equal to the target primary pressure, and since there is no shortage, belt slip does not occur.

  As described above, in this embodiment, when it is determined that the stationary shift fixing control is being executed, the stepping motor 40 is FF-controlled so that the primary pressure exceeds the target primary pressure, and then the primary pressure is set to the target primary. Since the step motor 40 is FB-controlled so as to be equal to the pressure, when the vehicle restarts after suddenly decelerating and stopping, a sufficient primary pressure is ensured and the primary pressure is insufficient, causing belt slippage. Can be prevented.

  Further, since the FB control is performed while the primary pressure is lowered after the step motor 40 is FF-controlled so that the primary pressure exceeds the target primary pressure, the primary pressure quickly becomes the target primary pressure, and the vehicle restarts after the vehicle stops. The required primary pressure can be ensured more reliably even when the time until is short.

  Furthermore, the target primary pressure is set so that the belt clamping force by the primary pulley 11 exceeds the maximum value of the clamping force that causes slipping between the primary pulley 11 and the belt 13, so that the belt slipping occurs when the vehicle restarts. Can be prevented.

  Furthermore, since the target primary pressure is set based on the stroke position of the primary pulley 11 and the temperature of the hydraulic oil, the primary pressure at the time of restart can be reliably ensured regardless of the operating conditions.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

It is a schematic block diagram which shows the hydraulic control apparatus of the belt-type continuously variable transmission in this embodiment. It is a conceptual diagram of a hydraulic control unit and CVTCU. It is a flowchart which shows control of the hydraulic control apparatus of the belt-type continuously variable transmission in this embodiment. It is a table which shows the relationship between a primary pressure and the number of steps required to implement | achieve the primary pressure. It is a table which shows the relationship between a hydraulic pressure deviation and the number of correction steps. It is a time chart which shows the change of the throttle opening in the past, a brake switch signal, a gear ratio, a step motor instruction value, a vehicle speed, and a primary pressure. 4 is a time chart showing changes in throttle opening, brake switch signal, gear ratio, step motor instruction value, vehicle speed, and primary pressure in the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter 3 Forward / reverse switching mechanism 4 Differential 10 Belt type continuously variable transmission 11 Primary pulley 11a Movable conical plate 11b Fixed conical plate 11c Primary pulley cylinder chamber 11d Input shaft 12 Secondary pulley 12a Movable conical plate 12b Fixed conical plate 12c Secondary pulley cylinder chamber 12d Output shaft 13 Belt 14 Idler gear 20 CVT control unit 21 Engine control unit 23 Inhibitor switch 24 Accelerator pedal stroke amount sensor 25 Oil temperature sensor 26 Primary pulley rotation speed sensor 27 Secondary pulley rotation speed sensor 30 Hydraulic control unit 31 Regulator Valve 32 Shift control valve 32a Spool 33 Pressure reducing valve 34 Hydraulic pump 35 Brake switch 40 Step motor 50 servo link

Claims (3)

A belt is wound around a primary pulley to which power output from a driving force source is input and a secondary pulley connected to the output side of the vehicle drive system, and a step motor is driven to reduce the hydraulic pressure supplied to the primary pulley. In a hydraulic control device for a continuously variable transmission that adjusts and changes the groove width of the primary pulley and the secondary pulley to change the rotational speed of the driving force source steplessly and output it,
Vehicle sudden stop determination means for determining that the vehicle has suddenly decelerated and stopped;
Primary pressure detection means for detecting a primary pressure which is a hydraulic pressure supplied to the primary pulley;
Target primary pressure setting means for setting a target primary pressure that is a target value of the primary pressure when the vehicle restarts;
When it is determined that the vehicle has suddenly decelerated and stopped, feed-forward control of the step motor so that the primary pressure exceeds the target primary pressure, and then the primary pressure becomes equal to the target primary pressure. Primary pressure control means for feedback control of the step motor;
A hydraulic control device for a continuously variable transmission.   The target primary pressure setting means is configured so that when the vehicle restarts, the clamping force of the belt by the primary pulley exceeds the maximum value of the clamping force that causes slipping between the primary pulley and the belt. The hydraulic control device for a continuously variable transmission according to claim 1, wherein a target primary pressure is set.   3. The continuously variable transmission according to claim 1, wherein the target primary pressure setting unit sets the target primary pressure based on at least one of a stroke position of the primary pulley and a temperature of hydraulic fluid. Hydraulic control device.

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