JP2008106813A - Hydraulic control device of belt continuously variable transmission for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device of a belt continuously variable transmission for a vehicle capable of starting the vehicle without slippage when the vehicle is started on a low-friction road surface. <P>SOLUTION: This hydraulic control device comprises a control means 20 for controlling the hydraulic pressure acting on a primary pulley 11 and a secondary pulley 12 and a pulley ratio selector means 29 for changing a target pulley ratio in starting the vehicle. The control means so controls the hydraulic pressure of the primary pulley and the secondary pulley that the pulley ratio becomes the target pulley ratio when the vehicle is stopped when the target pulley ratio 12 smaller than the present pulley ratio i1 is set by the pulley ratio selector means when the vehicle is stopped, and changes the pulley ratio to the target pulley ratio. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in a hydraulic control device for a belt type continuously variable transmission for a vehicle.

  In conventional belt-type continuously variable transmissions for vehicles, when the vehicle's starting surface is a low-friction surface such as a snowy road, icy road, or sand, it is used during normal starting to suppress wheel slippage during starting. There is a continuously variable transmission equipped with a so-called snow mode in which a gear ratio higher than the gear ratio to be selected is selected when starting (see Patent Document 1).

In the invention described in Patent Document 1, when the driver turns on the snow mode switch when the vehicle is stopped, the gear shift pattern is changed to the snow mode shift pattern, and the gear ratio at the normal start is the maximum gear ratio. As the target speed ratio, a speed ratio higher than the maximum speed ratio, for example, a maximum speed ratio at the time of limitation corresponding to the second speed of the stepped automatic transmission is set as the speed ratio at the start. Then, after the vehicle starts, the hydraulic pressure is controlled and the actual gear ratio is controlled to be the target gear ratio.
JP-A-11-63182

  However, in the above-described prior art, since the hydraulic control for shifting is started after the vehicle starts, it is impossible to prevent the vehicle from slipping in a transitional state until the actual transmission ratio reaches the target transmission ratio. There is.

  Accordingly, an object of the present invention is to provide a hydraulic control device for a belt-type continuously variable transmission for a vehicle that changes the actual gear ratio to a target gear ratio before starting the vehicle and reliably prevents slipping at the time of starting. To do.

  The present invention is wound around an input-side primary pulley whose groove width changes according to oil pressure, an output-side secondary pulley whose groove width changes according to oil pressure, the primary pulley and the secondary pulley, In a vehicular belt type continuously variable transmission having a V-belt whose pulley contact radius changes according to the groove width, a control means for controlling the hydraulic pressure acting on the primary pulley and the secondary pulley, and a target at the time of vehicle start Pulley ratio switching means for switching a pulley ratio, and the control means is configured to detect the target pulley while the vehicle is stopped when the pulley ratio switching means sets a target pulley ratio smaller than the current pulley ratio when the vehicle is stopped. The hydraulic pressure of the primary pulley and the secondary pulley is controlled so that the ratio becomes the ratio, and the pulley ratio is switched to the target pulley ratio. A hydraulic control device for a vehicular belt-type continuously variable transmission to.

  In the present invention, even when a pulley ratio smaller than the current pulley ratio is set as the target pulley ratio when the vehicle is stopped, the target pulley ratio is achieved by controlling the hydraulic pressure while the vehicle is stopped. The driving force can be efficiently transmitted to the road surface without any trouble.

  FIG. 1 is a schematic configuration diagram showing an embodiment of a belt type continuously variable transmission according to the present invention.

  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, 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 (primary 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 V 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 V 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 in accordance with hydraulic pressure (secondary 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 connects 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 CVT control unit 20 includes signals from the inhibitor switch 23, accelerator pedal stroke amount sensor 24, oil temperature sensor 25, primary pulley rotational speed sensor 26, secondary pulley rotational speed sensor 27, etc., and input torque information from the engine control unit 21. Is determined based on the target pulley ratio (the value obtained by dividing the effective radius of the secondary pulley 12 by the effective radius of the primary pulley 11 and synonymous with the gear ratio) and the contact friction force. Is transmitted to control the belt type continuously variable transmission 10.

  Further, the CVT control unit 20 outputs an output signal of a position sensor 40a that detects the position of a step motor 40 that displaces a shift control valve 32, which will be described later, and a shift mode of the continuously variable transmission 10, for example, an automatic mode for normal running, Shift pattern for selecting a snow mode for a low friction road surface that starts with a power mode for sports driving or running on an uphill road and a gear ratio smaller than the starting gear ratio for normal starting (for example, equivalent to the second speed of a stepped transmission). The output signal of the switch 29 is read.

  The hydraulic control unit 30 responds based on a command from the CVT control unit 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. Then, the V belt 13 moves on the primary pulley 11 and the secondary pulley 12. As a result, the contact radius of the V belt 13 with respect to the primary pulley 11 and the secondary pulley 12 changes, and the pulley ratio and the contact friction force of the V 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 V belt 13 and the secondary pulley 12.

  When the accelerator pedal is depressed or shift-changed in 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 V-belt 13. By doing so, the pulley ratio is continuously changed.

  FIG. 2 is a conceptual diagram of a hydraulic control unit and a CVT control unit of a belt type continuously variable transmission according to the present invention.

  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 the pressure of the oil pumped from the hydraulic pump 34 is set to a predetermined line pressure PL according to an operation state according to a command (for example, a duty signal) from the CVT control unit 20. It is a pressure regulating valve that regulates pressure.

  The shift control valve 32 is a control valve that controls the hydraulic pressure in the primary pulley cylinder chamber 11c (hereinafter referred to as “primary pressure”) to be the primary pulley 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, the actual pulley ratio feedback 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 pulley 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 (hereinafter referred to as “secondary pressure”) to the secondary pulley cylinder chamber 12 c to a secondary pulley target pressure.

  The line pressure PL 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 pulley ratio of the primary pulley 11 and the secondary pulley 12 is controlled by a step motor 40 driven according to a shift command signal from the CVT control unit 20, and shift control is performed according to the displacement of a servo link 50 that responds to the step motor 40. The spool 32a of the valve 32 is driven, the line pressure PL supplied to the transmission control valve 32 is adjusted, the primary pressure is supplied to the primary pulley 11, and the groove width is variably controlled to be set to a predetermined pulley ratio.

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

  The CVT control unit 20 determines a target pulley ratio according to the vehicle speed, throttle opening, etc., and drives the step motor 40 to control the current pulley ratio toward the target pulley ratio; A pulley pressure (hydraulic pressure) control unit 202 that controls the thrust of the primary pulley 11 and the secondary pulley 12 according to input torque, pulley ratio, oil temperature, target shift speed, and the like.

  The shift control unit 201 reads the stroke amount of the accelerator pedal 24, the select position signal of the shift range, the shift pattern signal, etc., calculates the target shift speed, outputs it to the pulley pressure control unit 202, and sends a shift command to the stepping motor 40. Output a signal. The stepping motor 40 having received the shift command signal controls the primary pressure of the primary pulley 11c by displacing the spool 32a of the shift control valve 32 based on the command signal.

  The pulley pressure control unit 202 determines the target value of the line pressure from the input torque information, the pulley ratio between the primary pulley and the secondary pulley, the oil temperature, and controls the line pressure by driving the solenoid of the regulator valve 31. Further, the target value of the secondary pressure is determined, the solenoid of the pressure reducing valve 33 is driven according to the detected value and the target value of the hydraulic sensor 28, and the secondary pressure is controlled by feedback control (closed loop control).

  In the hydraulic control apparatus for a belt type continuously variable transmission configured as described above, hydraulic control when the shift pattern is switched to the snow mode when the vehicle is stopped will be described with reference to the timing chart of FIG.

  In this hydraulic control, when the vehicle is stopped, the driver switches the shift pattern from automatic mode to snow mode so that the driver knows that the stop road surface is a low-friction road surface such as snow and starts smoothly. In this case, the hydraulic control is to switch to a smaller pulley ratio i2 instead of the pulley ratio i1 at the time of normal start during a stop.

  First, at time t1, when the vehicle speed VSP is 0 (vehicle stopped state) and the shift pattern is switched to the snow mode, the target pulley ratio is set to the highest (smallest pulley ratio ih). Based on the target pulley ratio, the position Aih of the step motor 40 is controlled so that the command pressure of the secondary pressure becomes 0 MPa and the command pressure of the primary pressure becomes the maximum pressure (= line pressure). Thus, when changing the pulley ratio from i1 to i2, the speed of each pulley can be increased by temporarily setting the target pulley ratio to the highest ih. By the hydraulic control based on the setting of the target pulley ratio, the contact radius of the primary pulley 11 with the V-belt is increased, while the contact radius of the secondary pulley 12 is decreased, whereby the pulley ratio can be decreased. Here, the engine speed may be increased to increase the line pressure.

  With this hydraulic pressure control, the pulley ratio i shifts from the pulley ratio i1 when starting in the auto mode to the pulley ratio i2 (i1> i2) when starting in the snow mode when the vehicle is stopped. The actual pulley ratio cannot be detected because each pulley is stopped, and the position of the secondary pulley 12 estimated from the secondary pressure detected by the hydraulic sensor 28 and the position of the step motor 40 are detected. The pulley ratio i is calculated from the position of the primary pulley 11 estimated by the position sensor 40a.

  When the pulley ratio i reaches i2 which is the pulley ratio at the start of the snow mode (time t2), the target pulley ratio is switched from ih to i2 which is the pulley ratio at the start of the snow mode. As a result, the position of the step motor 40 and the secondary pressure are controlled to a pressure that achieves the pulley ratio i2.

  When the position of the step motor 40 and the secondary pressure correspond to the target pulley ratio i2 at time t3, the vehicle can start smoothly without causing slip even if it starts.

  Therefore, in the present invention, in the belt type continuously variable transmission for a vehicle, the CVT control unit 20 that controls the hydraulic pressure acting on the primary pulley and the secondary pulley, and the shift pattern switch 29 that switches the target pulley ratio at the start of the vehicle. The CVT control unit 20 includes a primary pulley 11 and a secondary pulley 12 so that the target pulley ratio is obtained when the shift pattern switch 29 is switched from the automatic mode to the snow mode in which the target pulley ratio at the time of starting is smaller. In order to control the hydraulic pressure acting on the vehicle, it is switched to the pulley mode at the start of the snow mode, which is smaller than the pulley ratio at the start of the automatic mode when the vehicle starts. Can communicate.

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

1 is a schematic configuration diagram showing a belt type continuously variable transmission for a vehicle according to the present invention. It is a block diagram explaining the detailed structure of a primary pressure regulator. It is a timing chart explaining hydraulic control of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter 10 Belt type continuously variable transmission 11 Primary pulley 12 Secondary pulley 13 V belt 20 CVT control unit 21 Engine control unit 26 Primary pulley rotational speed sensor 27 Secondary pulley rotational speed sensor 28 Hydraulic sensor 29 Shift pattern switch 30 Hydraulic pressure Control unit 31 Hydraulic pump 32 Shift control valve 32a Spool 40 Stepping motor 40a Position sensor

Claims (4)

A primary pulley on the input side whose groove width changes according to the hydraulic pressure;
A secondary pulley on the output side whose groove width changes according to the hydraulic pressure;
In a vehicular belt type continuously variable transmission comprising a V-belt wound around the primary pulley and the secondary pulley and having a pulley contact radius that changes according to the groove width,
Control means for controlling oil pressure acting on the primary pulley and the secondary pulley;
Pulley ratio switching means for switching the target pulley ratio when the vehicle starts,
The control means is configured such that when the target pulley ratio smaller than the current pulley ratio is set by the pulley ratio switching means when the vehicle is stopped, the primary pulley and the secondary pulley are set to the target pulley ratio while the vehicle is stopped. A hydraulic control device for a belt type continuously variable transmission for a vehicle, wherein the hydraulic pressure of the vehicle is controlled and the pulley ratio is switched to a target pulley ratio.   When the target pulley ratio is set, the control means supplies the hydraulic oil having the maximum hydraulic pressure to the primary pulley, changes the pulley ratio so that the hydraulic pressure acting on the secondary pulley is zero, and the pulley ratio is the target pulley. 2. The belt-type continuously variable transmission for a vehicle according to claim 1, wherein the hydraulic pressure acting on the primary pulley and the secondary pulley is controlled so that the pulley ratio maintains a target pulley ratio after reaching the ratio. Hydraulic control device.   When the target pulley ratio is set, the control means controls the hydraulic pressure acting on the primary pulley and the secondary pulley to be the smallest pulley ratio, and after the pulley ratio reaches the target pulley ratio 2. The hydraulic control apparatus for a belt type continuously variable transmission for a vehicle according to claim 1, wherein the hydraulic pressure acting on the primary pulley and the secondary pulley is controlled so that the pulley ratio maintains a target pulley ratio. A hydraulic pressure sensor for detecting a hydraulic pressure acting on the secondary pulley;
A step motor that changes the position in accordance with a signal from the control means and adjusts the hydraulic pressure of the hydraulic oil supplied to the primary pulley;
A position sensor for detecting the position of the step motor,
4. The belt-type continuously variable vehicle according to claim 1, wherein the pulley ratio when the vehicle is stopped is estimated from a detected hydraulic pressure of the secondary pulley and a detected position of the step motor. Hydraulic control device for transmission.