JPH08178042A - Speed change control device for continuously variable transmission - Google Patents

Abstract

PURPOSE: To prevent a motor from being enlarged by preventing the driving force of the motor operating a speed change control valve from being increased at the time of a low temperature when the viscous resistance of the speed change control valve is increased. CONSTITUTION: A controller 17 obtains the target input revolving speed Nis from the vehicle speed VSP and throttle opening TVO and operates a speed change control valve 21 with a step motor 23 via a link 22 in response to it. The valve 21 regulates the control pressure PS, and the transmission ratio between pulleys 1, 2 is continuously changed to the ratio corresponding to the target input revolving speed Nis . The controller 17 further reduces the driving speed of the motor 23 at a lower temperature in response to the operating oil temperature T. The driving force of the motor 23 is not increased at the time of a low temperature when the viscous resistance of the valve 21 is increased, and the motor 23 can be prevented from being enlarged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed change control device such as a V-belt type continuously variable transmission and a toroidal type continuously variable transmission.
In particular, the present invention relates to a technique for avoiding an increase in the size of a motor that strokes a shift control valve to a position corresponding to a gear ratio command in the shift control device.

[0002]

2. Description of the Related Art A V-belt type continuously variable transmission is described as an example of a continuously variable transmission, and its shift control device is suitable for operating conditions as described in, for example, Japanese Patent Application Laid-Open No. 61-105347. The target gear ratio is calculated, and a gear ratio command corresponding to the target gear ratio is used to rotate a motor such as a step motor or a servo motor to operate the gear shift control valve to a stroke position corresponding to the target gear ratio. By this operation, the shift control valve produces and outputs a shift control pressure corresponding to the target gear ratio, and the continuously variable transmission responds to the shift control pressure and continuously shifts toward the target gear ratio.

[0003]

By the way, conventionally, when driving the above-mentioned motor, it is common practice to drive the motor at a constant speed without basically controlling the motor drive speed. When the deviation from the actual gear ratio is large, a technique for increasing the motor drive speed in order to improve the gear shift response has been scattered.

However, even if the motor drive speed is not controlled or is controlled as described above, it has been confirmed that the following problems occur if the motor drive speed is changed according to the gear ratio deviation. That is, the viscosity of the hydraulic fluid of the continuously variable transmission changes according to the temperature, and becomes high at low temperature. In addition, the clearance between the valve body of the shift control valve, which is usually made of aluminum, and the spool of the shift control valve, which is usually made of iron, becomes smaller at lower temperatures. For these reasons, when the hydraulic oil temperature is low, the viscous resistance when the shift control valve is stroked is large, and the required driving force of the motor that strokes the shift control valve is large when the temperature is low.

On the other hand, in designing the shift control device, the motor is designed so that the motor driving force is sufficient to satisfy the requirement also at low temperature when the viscous resistance of the shift control valve becomes large. For this reason, in the past, the motor had to be a high-output type motor, which inevitably increased in size.
Otherwise, the shift control may lose control.

According to the present invention, even if the operating oil temperature is the same (the viscous resistance of the speed change control valve is the same), the required driving force of the motor is reduced by decreasing the motor driving speed.
The motor drive speed is controlled according to the transmission operating fluid temperature so that the required drive force of the motor does not increase even when the temperature is low. The purpose is to eliminate.

[0007]

To this end, the gear shift control device according to the first aspect of the present invention operates the gear shift control valve by rotating the motor to a position corresponding to the target gear ratio, and in response to this operation, the gear shift control valve is operated. In a continuously variable transmission in which a gear ratio is determined by a shift control pressure output by a control valve, an oil temperature detecting means for detecting a working oil temperature of the continuously variable transmission, and a working oil temperature detected by the means are provided. Motor drive speed control means for changing the drive speed of the motor in accordance therewith is provided.

Also, in the shift control device for a continuously variable transmission according to the second aspect of the invention, the motor drive speed control means is configured to slow down the drive speed of the motor as the operating oil temperature decreases. is there.

[0009]

In the first aspect of the invention, the shift control device for a continuously variable transmission operates the shift control valve by rotating the motor to a position corresponding to the target gear ratio. By this operation, the shift control valve produces a corresponding shift control pressure, and the continuously variable transmission responds to this shift control pressure and continuously shifts toward the target gear ratio.

On the other hand, the oil temperature detecting means detects the operating oil temperature of the continuously variable transmission, and the motor drive speed control means changes the drive speed of the motor according to the detected operating oil temperature of the transmission. Therefore, the drive speed of the motor is slowed down under the operating oil temperature of the transmission where the viscous resistance of the speed change control valve increases, and the required drive force of the motor is reduced. It is not necessary to use a large output, and it is possible to avoid the increase in size.

In the second aspect of the invention, the motor drive speed control means slows the drive speed of the motor as the operating oil temperature becomes lower. In this case, the viscous resistance of the shift control valve increases and the required driving force of the motor increases as the temperature decreases, but this is offset by the decrease control of the motor driving speed, and the required driving force of the motor increases. This can be prevented, and the above-described effect of the first aspect of the invention, which is to prevent the motor from increasing in size, can be made more reliable.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a shift control device of the present invention configured for a V-belt type continuously variable transmission, wherein the V-belt type continuously variable transmission includes a primary pulley 1 as an input pulley for inputting engine rotation, A secondary pulley 2 serving as an output pulley that outputs rotation after shifting is provided, and a V-belt 3 is wound around the primary pulley 1 and the secondary pulley 2 to form a transmission system. The V-belt type continuously variable transmission has a V-belt 3 for both pulleys 1 and 2.
It is possible to change the transmission ratio between pulleys, that is, the gear ratio infinitely by changing the diameter of the winding arc.

In order to enable such a continuously variable transmission, the primary pulley 1 has a movable flange 1b that faces the fixed flange 1a and forms a pulley V groove, and is displaceable in the axial direction, and the secondary pulley 2 also has a fixed flange. The movable flange 2b that faces the groove 2a and forms the pulley V groove is displaceable in the axial direction. Then, the shift control pressure P _S is applied to the movable flange 1b in the direction toward the fixed flange 1a, and the line pressure P _L is applied to the movable flange 2b in the direction toward the fixed flange 2a, so that the shift control pressure P _S and the line It is assumed that the diameter of the circular arc around which the V-belt 3 is wound around the pulleys 1 and 2 is changed steplessly in accordance with the pressure difference from the pressure P _L to perform continuously variable transmission.

The line pressure control system for controlling the line pressure P _L will be described below.
A pressure regulator valve 12 for adjusting the hydraulic fluid from now on to a line pressure P _L; a pressure modifier valve 13 for supplying a line pressure control modifier pressure P _m to the pressure regulator valve; (A) A line pressure solenoid 14 for controlling the valve 13 and a pilot valve 15 for supplying a constant pressure P _C to the solenoid.

[0015] Pressure regulator valve 12, while leakage of hydraulic oil from the pressure source 11 to the circuit 16, also with a drain from the drain port 12 _a as required line pressure according to the modifier pressure P _m P _L Regulate to. The pilot valve 15 is supplied to the line pressure solenoid 14 leaks oil into a constant pressure P _C from the circuit 16, the line pressure solenoid 14 in the duty pressure P _D corresponding to a constant pressure P _C in the drive duty D modifier valve 13 is applied.
The modifier valve 13 makes the oil leaked from the circuit 16 a modifier pressure P _m corresponding to the duty pressure P _D , and thus the drive duty D of the line pressure solenoid 14, and applies this to the pressure regulator valve 12 to apply the line pressure P _L.
Contribute to the above control of. Therefore, the line pressure P _L can be controlled by adjusting the drive duty D of the line pressure solenoid 14, and the solenoid drive duty D is determined by the controller 17.

The controller 17 also controls the gear shift. Therefore, the controller 17 has a signal from the vehicle speed sensor 18 for detecting the vehicle speed VSP and a signal from the throttle opening sensor 19 for detecting the engine throttle opening TVO. And a signal from an oil temperature sensor 20 forming an oil temperature detecting means for detecting the transmission operating oil temperature T, respectively.

Next, the shift control system will be described. It is composed of a shift control valve 21 for determining the shift control pressure P _S , a shift link 22, and a step motor 23. The speed change link 22 has one end connected to a shifter 24 which is displaced together with the primary pulley movable flange 1b, the other end connected to be rotated by a step motor 23, and the both ends are pivotally attached to a spool 21a of the speed change control valve 21. To do. Here, the shift control valve 2
Reference numeral 1 is for reducing the line pressure P _L from the circuit 25 to create the shift control pressure P _S in the circuit 26. When the spool 21a is raised in the drawing, the shift control pressure circuit 26 is set to the line pressure circuit 2
5, the shift control pressure P _S is increased, and the spool 21a
When it is lowered in the figure, the shift control pressure circuit 26 is connected to the drain port 21b to reduce the shift control pressure P _S , and the stroke of the spool 21a is controlled by the step motor 23 via the shift link 22. Then, the rotational position of the step motor 21 is determined by the controller 17, and the following shift control is executed accordingly.

In this shift control, the controller 17
Executes the control program shown in FIG. 2, for example. First, at step 31, the vehicle speed VSP, the throttle opening TVO, and the hydraulic oil temperature T are read. Next, at step 32, the target input speed N _iS is obtained from the vehicle speed VSP and the throttle opening TVO based on the map corresponding to the shift control characteristic shown in FIG. 3, and the target of the step motor 23 corresponding to this is obtained. Rotation position STEP
Calculate _pS .

In the next step 34 corresponding to the motor drive speed control means, for example, the transmission operating oil temperature T is calculated based on the map corresponding to the step motor drive speed characteristics shown in FIG.
Each step motor drive speed STEP _Sp is searched.
Here, the step motor drive speed characteristic is such that the step motor drive speed STEP _Sp becomes slower as the transmission operating oil temperature T becomes lower, as shown in FIG. Even if the viscosity resistance of the shift control valve 21 increases as the temperature T decreases, the step motor 2
It is preferable to set the motor drive speed so that the required drive force of 3 does not increase.

Next, at step 35, the step motor 23 is driven by the motor drive speed ST according to the hydraulic oil temperature T.
At EP _Sp, it is rotated to the target rotation position STEP _pS .
As a result, the step motor 23 shifts the link 22 to the shifter 2
4 to rotate the shift control valve spool 21a to the corresponding position. As a result, the shift control valve 21
Changes the gear shift control pressure P _S, and the movable flanges 1b and 2b of the pulleys 1 and 2 are displaced, so that the gear ratio is brought to the gear ratio corresponding to the target input speed N _iS .

As the speed change progresses, the movable flange 1b of the primary pulley 1 rotates the speed change link 22 around the step motor 23 through the shifter 24 so as to return the speed change control valve spool 21a to the original stroke position.
When the gear ratio reaches the gear ratio corresponding to the target input speed N _iS , the gear shift control ends, and this gear ratio can be maintained.

The line pressure P_LTo control the
At the gear ratio and the throttle opening TVO
A map corresponding to the specified prescribed line pressure control characteristics
Based on the above gear ratio and throttle opening TVO
Target line pressure P_LDrive corresponding to this
The duty D is commanded to the line pressure solenoid 14. This
Here, the solenoid 14 has a constant pressure from the pilot valve 15.
P_CThe duty pressure P according to the drive duty D_DWest
Applied to the modifier valve 13 and the modifier valve 1
3 is a modifier pressure P according to the duty D_mThe pre
Apply to the pressure regulator valve 12 to
The guulator valve 12 is used to depress the hydraulic oil from the pressure source 11.
Line pressure P according to tee D_LRegulate to. Due to the above
In pressure P _LIs in line with the prescribed line pressure control characteristics described above.
Controlled.

By the way, in this example, the operating oil temperature T of the continuously variable transmission is detected, and the driving speed of the step motor 23 is changed in accordance with the operating oil temperature T. Since the driving speed is slowed down, the required driving force of the step motor 23 can be reduced at a low temperature when the viscous resistance of the shift control valve 21 is increased, and the required driving force can be kept the same as that at the high temperature. Therefore, it is not necessary to increase the output of the step motor 23, and the increase in size can be avoided.

[0024]

As described above, the shift control device for a continuously variable transmission according to the first aspect of the present invention, as set forth in claim 1, is a motor for performing stroke control of the shift control valve according to the operating oil temperature of the continuously variable transmission. Since the drive speed is changed, the drive speed of the motor is reduced under the operating oil temperature of the transmission where the viscous resistance of the speed change control valve increases to reduce the required drive force of the motor. Speed control is possible,
It is not necessary to use a motor with a large output, and it is possible to avoid the increase in size.

According to the second aspect of the present invention, the shift control device for a continuously variable transmission has a structure in which the driving speed of the motor is slowed down as the working oil temperature lowers. Although the viscous resistance of the valve increases and the required driving force of the motor increases, this can be offset by the reduction control of the motor driving speed, and the required driving force of the motor can be prevented from increasing. It is possible to further secure the above-described effect of the first invention of avoiding the increase in size.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a shift control device of the present invention, which is suitably configured for a V-belt type continuously variable transmission.

FIG. 2 is a flowchart showing a shift control program executed by a controller in the same example.

FIG. 3 is a shift control pattern diagram used in shifting in the example.

FIG. 4 is a control diagram of a drive speed of a step motor set in the same example.

[Explanation of symbols]

1 Primary pulley 1b Movable flange 2 Secondary pulley 2b Movable flange 3 V belt 11 Pressure source 12 Pressure regulator valve 13 Pressure modifier valve 14 Line pressure solenoid 15 Pilot valve 17 Controller 18 Vehicle speed sensor 19 Throttle opening sensor 20 Oil temperature sensor (oil Temperature detecting means) 21 Shift control valve 22 Shift link 23 Step motor 24 Shifter 25 Line pressure circuit 26 Shift control pressure circuit P _L line pressure P _S Shift control pressure

Claims (2)

[Claims] 1. A speed change control valve is operated by rotating a motor to a position corresponding to a target speed change ratio, and the speed change ratio is determined by the speed change control pressure output by the speed change control valve in response to this operation. In the continuously variable transmission, an oil temperature detecting means for detecting a hydraulic oil temperature of the continuously variable transmission, and a motor drive speed control means for changing a drive speed of the motor according to the hydraulic oil temperature detected by the means. A shift control device for a continuously variable transmission, comprising: 2. The shift control device for a continuously variable transmission according to claim 1, wherein the motor drive speed control means is configured to decrease the drive speed of the motor as the hydraulic oil temperature decreases.