JP2006097811A - Line pressure control system in belt-type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic control device by which an excess line-pressure command is inhibited from being issued by a simple constitution. <P>SOLUTION: The steady deviation of required primary pressure from the total pressure of real primary pressure and marginal pressure computed by a marginal pressure-setting part 301 is reduced by a compensator 305. Consequently, the post-correction required primary pressure which has been excessively estimated can be optimally corrected. When a line-pressure command value is computed on the basis of the post-correction required primary pressure in a line-pressure command-value selector 304, the line-pressure command value is reduced as compared in the case that the required primary pressure is not corrected, and the line pressure command is inhibited without constituting a feedback circuit, etc. by providing a line-pressure sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a line pressure control device in a belt type continuously variable transmission.

Conventionally, as a continuously variable transmission suitable for vehicles, there is a belt type continuously variable transmission (hereinafter referred to as a belt CVT) using a V belt. This belt CVT spans a V-belt between a primary pulley and a secondary pulley, and variably controls the groove width of the primary pulley and the secondary pulley by hydraulic pressure.
An oil pump is connected to the input shaft side of the belt CVT, and a hydraulic pressure generated by the oil pump is regulated by a pressure regulating valve to generate a line pressure. A primary pulley cylinder chamber and a secondary pulley cylinder chamber are attached to the primary pulley and the secondary pulley, respectively, and the primary pulley cylinder chamber is supplied with the primary pressure obtained by adjusting the line pressure with the speed change control valve, and the secondary pulley cylinder chamber Supply secondary pressure with line pressure regulated by pressure regulating valve. The groove widths of the primary pulley and the secondary pulley are changed by the hydraulic pressure supplied to each cylinder chamber, and the gear ratio continuously changes corresponding to the contact radius ratio between the V belt and each pulley.

The line pressure instruction value to be instructed to the pressure regulating valve to generate the line pressure is calculated based on the maximum oil pressure necessary for driving each part in the transmission.
Of the required oil pressure, the primary ones are the primary pressure and the secondary pressure. The secondary pressure is controlled using a hydraulic feedback circuit, and the primary pressure is controlled by receiving hydraulic mechanical feedback from a speed change link driven by a step motor to operate the pressure regulating valve.
Further, for fail-safe etc., a primary pressure sensor for detecting the primary pressure and a secondary pressure sensor for detecting the secondary pressure are provided in the hydraulic pressure supply path to each pulley.
JP 2002-266277 A

However, in the conventional belt type CVT, since a feedback circuit based on actual pressure observation is not added to the line pressure, when the line pressure is calculated based on the primary pressure, a variation in hydraulic pressure becomes a problem. As a countermeasure, variation compensation was performed. However, because the operable range of the compensator is limited, it is necessary to take a margin to include the worst variation in the initial state, resulting in excessive line pressure. It was.
In order to prevent this, it is conceivable to reduce the hydraulic pressure variation by configuring the feedback circuit by applying the line pressure sensor and reduce the excess of the line pressure, but there is a problem that the cost increases. .

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic control device in a belt type continuously variable transmission that avoids an excessive line pressure command with a simple configuration.

  The present invention includes a primary pulley that is connected to the engine side and acts on the primary pressure, a secondary pulley that is connected to the output shaft side and acts on the secondary pressure, a belt stretched between both pulleys, the primary pressure and the secondary pressure The primary pressure is generated from the line pressure by the line pressure control unit that controls the line pressure as the base pressure, the step motor driven by the gear change command, the step motor, and the feedback of the actual gear ratio. In a line pressure control device for a belt-type continuously variable transmission equipped with a shift control valve, a primary pressure sensor that detects an actual primary pressure as an actual primary pressure, a line pressure control unit, and a primary pulley And a compensation unit that corrects the necessary primary required pressure. The primary required pressure is corrected to calculate a corrected primary required pressure so that the steady deviation of the primary required pressure with respect to the margin is reduced, and the line pressure control unit determines the corrected primary required pressure and the secondary required for the secondary pulley. Based on the required pressure, a line pressure instruction value that is an instruction value for line pressure control is calculated, and the line pressure is controlled.

According to the present invention, the compensator calculates the corrected primary required pressure by correcting the primary required pressure so that the steady deviation of the primary required pressure required for the primary pulley relative to the actual primary pressure is reduced. The estimated primary required pressure after correction can be optimally corrected. Therefore, when the line pressure control unit calculates the line pressure instruction value based on the corrected primary required pressure, the line pressure instruction value is reduced and the line pressure is reduced compared to the case where the primary required pressure is not corrected. be able to.
In this way, an excessive line pressure command can be avoided without using a new line pressure sensor and configuring a feedback circuit or the like simply by using a primary pressure sensor originally provided for redundant control or the like.

Next, embodiments of the present invention will be described by way of examples.
FIG. 1 shows a schematic configuration in which the present invention is applied to a belt CVT, and FIG. 2 shows a schematic configuration of a hydraulic control unit and a CVT control unit.
In FIG. 1, a belt CVT 3 including a speed change mechanism 5 having a forward / reverse switching mechanism (not shown) and a torque converter 2 having a lock-up clutch is connected to the engine 1. The transmission mechanism unit 5 includes a primary pulley 10 on the input shaft side as a pair of variable pulleys and a secondary pulley 11 connected to the output shaft 13. The pair of variable pulleys 10 and 11 are connected by a V belt 12. The output shaft 13 is connected to the differential 6 via an idler gear 14.

  The transmission ratio of the transmission mechanism unit 5 and the contact friction force of the V belt 12 are controlled by a hydraulic control unit 100 that operates according to a command from the CVT control unit 20. The CVT control unit 20 is connected to an engine control unit (hereinafter referred to as ECU) 21 that controls the engine 1 and exchanges information with each other. The CVT control unit 20 determines the gear ratio and the contact friction force from the input torque information from the ECU 21 and the throttle opening (TVO) from the throttle opening sensor 24. The ECU 21 is connected to an engine speed sensor 15 that detects the speed of the engine 1.

The primary pulley 10 of the transmission mechanism unit 5 is disposed at a position opposed to the fixed conical plate 10b that rotates integrally with the input shaft and the fixed conical plate 10b to form a V-shaped pulley groove. The movable conical plate 10a can be displaced in the axial direction in accordance with the primary pressure acting on the cylinder chamber 10c.
The secondary pulley 11 is disposed at a position opposed to the fixed conical plate 11b that rotates integrally with the output shaft 13 and the fixed conical plate 11b to form a V-shaped pulley groove, and to the secondary pulley cylinder chamber 11c. The movable conical plate 11a can be displaced in the axial direction according to the acting secondary pressure.

  Input torque input from the engine 1 is input to the transmission mechanism 5 via the torque converter 2 and transmitted from the primary pulley 10 to the secondary pulley 11 via the V belt 12. By moving the movable conical plate 10a of the primary pulley 10 and the movable conical plate 11a of the secondary pulley 11 in the axial direction and changing the contact radius between the V belt 12 and the pulleys 10 and 11, the primary pulley 10 and the secondary pulley 11 can be continuously changed.

As shown in FIG. 2, the hydraulic control unit 100 includes a pressure regulating valve 60 that controls line pressure, a transmission control valve 30 that controls primary (Pri) pressure to the primary pulley cylinder chamber 10c, and a secondary pulley cylinder chamber 11c. The pressure reducing valve 61 that controls the secondary (Sec) pressure is mainly configured.
The speed change control valve 30 is connected to a speed change link 50 that constitutes a mechanical feedback mechanism, is driven by a step motor 40 connected to one end of the speed change link 50, and the primary pulley 10 connected to the other end of the speed change link 50 is movable. The groove width, that is, feedback of the actual gear ratio is received from the conical plate 10a.

  The line pressure control system includes a pressure regulating valve 60 including a solenoid 59 that regulates the pressure oil from the hydraulic pump 80, and a predetermined pressure corresponding to an operation state according to a command (for example, a duty signal) from the CVT control unit 20. Regulate to line pressure. The line pressure is supplied to a speed change control valve 30 that controls the primary pressure and a pressure reducing valve 61 that includes a solenoid 62 that controls the secondary pressure. The hydraulic pump 80 is connected to the input shaft of the belt CVT 3 and generates hydraulic pressure using the engine rotation as a power source.

The gear ratio of the primary pulley 10 and the secondary pulley 11 is controlled by a step motor 40 driven in accordance with a shift command signal from the CVT control unit 20, and the shift control is performed in accordance with the displacement of the shift link 50 that responds to the step motor 40. The spool 31 of the valve 30 is driven, the primary pressure obtained by adjusting the line pressure supplied to the speed change control valve 30 is supplied to the primary pulley 10, and the groove width is variably controlled to be set to a predetermined speed ratio.
The shift control valve 30 supplies and discharges hydraulic pressure to and from the primary pulley cylinder chamber 10c by displacement of the spool 31, and adjusts the primary pressure so that the target gear ratio commanded at the drive position of the step motor 40 is obtained. When the shift is actually completed, the spool 31 is closed in response to the displacement from the shift link 50.

  Here, the CVT control unit 20 in FIG. 1 includes a primary pulley speed sensor 26 that detects the rotational speed of the primary pulley 10 of the transmission mechanism unit 5 and a secondary pulley speed sensor 27 that detects the rotational speed (or vehicle speed) of the secondary pulley 11. The signal from the secondary pressure sensor 28 that detects the actual secondary pressure acting on the secondary pulley cylinder chamber 11c of the secondary pulley, the range signal from the inhibitor switch 23, and the throttle that opens and closes when the driver operates the accelerator pedal The throttle opening degree (TVO) from the throttle opening degree sensor 24 that detects the opening degree and the oil temperature of the speed change mechanism unit 5 detected by the oil temperature sensor 25 are read to determine the gear ratio and the contact friction force of the V belt 12. Variable control.

  The CVT control unit 20 determines a target gear ratio according to the vehicle speed, the throttle opening, etc., and drives the step motor 40 to control the actual gear ratio toward the target gear ratio. It comprises a pulley pressure control unit 202 that calculates the thrust (contact friction force) of the primary pulley 10 and the secondary pulley 11 according to the gear ratio, the oil temperature, etc., and converts the calculated thrust into hydraulic pressure.

  The pulley pressure control unit 202 determines the primary required pressure required for the primary pulley from the input torque information, the gear ratio based on the primary pulley rotational speed and the secondary pulley rotational speed, the oil temperature, the secondary required pressure required for the secondary pulley, A required clutch pressure to be applied to the switching clutch is calculated, a line pressure command value that is a target value of the line pressure is determined based on the highest required pressure among these required pressures, and based on the line pressure command value The line pressure is controlled by driving the solenoid 59 of the pressure regulating valve 60.

Further, the pulley pressure control unit 202 determines a secondary target pressure that is a target value of the hydraulic pressure supplied to the secondary pulley from the secondary required pressure, and drives the solenoid 62 of the pressure reducing valve 61 according to the secondary target pressure to perform feedback control ( The secondary pressure is controlled by closed loop control.
Further, a signal from the primary pressure sensor 29 that detects the actual primary pressure acting on the primary pulley cylinder chamber 10 c is input to the pulley pressure control unit 202.

Next, the details of the process of calculating the line pressure instruction value by the pulley pressure control unit 202 will be described.
FIG. 3 is a functional block diagram of the pulley pressure control unit 202.
The pulley pressure control unit 202 calculates a primary required pressure calculation unit 300 that calculates a primary required pressure from a primary pulley input torque estimated value obtained from input torque information and a gear ratio obtained from a primary pulley rotation speed and a secondary pulley rotation speed. Is provided.

The pulley pressure control unit 202 includes a margin pressure setting unit 301 and a compensation unit 305 having a PI compensator 302.
The compensation unit 305 uses the PI compensator 302 to reduce the steady deviation of the primary required pressure with respect to the total pressure of the actual primary pressure and the margin pressure.
The compensator 305 is intended to reduce the steady-state deviation, so that the characteristic of the PI compensator 302 is slow.

  The margin pressure setting unit 301 includes the maximum value of the hydraulic pressure variation in the primary pressure and line pressure hydraulic systems, and the maximum change in the dynamic characteristics of the line pressure occurs during one calculation cycle of the line pressure command value. In this case, the margin pressure is set so that the primary required pressure does not exceed the total pressure of the actual primary pressure and the margin pressure.

The corrected primary required pressure output from the compensation unit 305 is input to the limit processing unit 303. Further, the margin pressure set by the margin pressure setting unit 301 and the actual primary pressure are input to the limit processing unit 303.
When the corrected primary required pressure output from the compensation unit 305 is lower than the total value of the actual primary pressure and the margin pressure, the limit processing unit 303 corrects the total pressure of the actual primary pressure and the margin pressure. Output as primary required pressure.
On the other hand, if the corrected primary required pressure output from the compensation unit 305 is higher than the total pressure of the actual primary pressure and the margin pressure, the corrected primary required pressure output from the compensation unit 305 is output.

The corrected primary required pressure output from the limit processing unit 303 is input to the line pressure command value selection unit 304. Further, the secondary required pressure and the clutch required pressure are input to the line pressure command value selection unit 304.
The line pressure command value selection unit 304 selects the highest necessary pressure among the input necessary pressures and outputs it as a line pressure command value.

After the corrected primary required pressure is once output from the limit processing unit 303, the corrected primary required pressure calculated by the limit processing unit 303 is used instead of the primary required pressure calculated by the primary required pressure calculation unit 300. Is input to the compensation unit 305 as the primary required pressure, and the process for reducing the steady-state deviation in the compensation unit 305 is repeated.
The margin pressure set in the margin pressure setting unit 301 is always set so as to satisfy the corrected primary required pressure> the actual primary pressure.
In this embodiment, the limit processing unit 303 and the line pressure command value selection unit 304 constitute a line pressure control unit in the present invention.

This embodiment is configured as described above, and the compensation unit 305 reduces the primary required pressure that has been overestimated by reducing the steady deviation of the primary required pressure with respect to the total pressure of the actual primary pressure and the margin pressure. It can be corrected optimally. Therefore, when the line pressure command value is calculated based on the corrected primary required pressure in the line pressure command value selection unit 304, the line pressure command value is reduced and the line pressure is lower than when the primary required pressure is not corrected. Can be.
Thus, an excessive line pressure command can be avoided without applying a line pressure sensor and configuring a feedback circuit or the like. (Effects corresponding to claim 1)

The purpose of correcting the primary required pressure is to reduce the steady-state deviation. By making the characteristic of the PI compensator 302 slow, it is possible to avoid excessive correction of the primary required pressure. (Effects corresponding to claims 1 and 2)
Further, the margin pressure setting unit 301 sets the margin pressure so as to include the maximum value of the hydraulic pressure variation in the hydraulic system of the primary pressure and the line pressure.
As a result, even if the hydraulic pressure varies due to the primary pressure and line pressure hydraulic system sensors and actuators, the margin pressure is set appropriately to avoid overcorrection of the primary required pressure. can do. (Effects corresponding to claim 3)

Furthermore, the margin pressure setting unit 301 also determines that the primary required pressure is the total pressure of the actual primary pressure and the margin pressure even when the maximum change in the dynamic characteristics of the line pressure occurs during one calculation cycle of the line pressure command value. Set the margin pressure so as not to exceed.
As a result, the primary pressure is determined by the mechanical feedback mechanism, but the primary required pressure does not exceed the total pressure of the actual primary pressure and the margin pressure even when the primary pressure is suddenly changed by the feedback mechanism. There is no contradiction between the actual primary pressure and the corrected primary required pressure. (Effects corresponding to claim 4)

  After the corrected primary required pressure is once calculated in the limit processing unit 303, the corrected primary required pressure is input to the compensation unit 305 and correction is performed to reduce the steady-state deviation. The required primary pressure can be optimized. (Effects corresponding to claim 5)

  In the limit processing unit 303, when the corrected primary required pressure output from the compensation unit 305 is lower than the total pressure of the actual primary pressure and the margin pressure, the total pressure of the actual primary pressure and the margin pressure is calculated as the limit processing unit 303. Therefore, the corrected primary required pressure can be prevented from being excessively corrected even when the PI compensator 302 becomes unstable. (Effect corresponding to claim 6)

  Further, the line pressure command value selection unit 304 calculates the line pressure command value appropriately based on the highest pressure among the corrected primary required pressure, secondary required pressure, and clutch required pressure. Can be calculated. (Effects corresponding to claims 6 and 7)

It is a figure which shows the Example in this invention. It is a figure which shows schematic structure of a hydraulic control unit and a CVT control unit. It is a functional block diagram of a pulley pressure control part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Primary pulley 20 Secondary pulley 20 CVT control unit 29 Primary pressure sensor 30 Shift control valve 60 Pressure regulation valve 61 Pressure-reducing valve 80 Hydraulic pump 100 Hydraulic control unit 201 Shift control unit 202 Pulley pressure control unit 300 Primary required pressure calculation unit 301 Margin pressure setting Unit 302 PI compensator 303 limit processing unit 304 line pressure command value selection unit 305 compensation unit

Claims (8)

A primary pulley connected to the engine side and acting on the primary pressure; a secondary pulley connected to the output shaft side and acting on the secondary pressure; a belt stretched around the pulleys; a base of the primary pressure and the secondary pressure A line pressure control unit for controlling the line pressure to be a pressure, a step motor driven by a shift command, and a primary pressure generated from the line pressure by being driven by the step motor and receiving feedback of an actual gear ratio. In a line pressure control device in a belt-type continuously variable transmission including a shift control valve,
A primary pressure sensor that detects an actual hydraulic pressure of the primary pressure as an actual primary pressure;
A compensation unit for correcting the primary required pressure required for the primary pulley,
The compensator calculates a corrected primary required pressure by correcting the primary required pressure so that a steady deviation of the primary required pressure with respect to the actual primary pressure is reduced.
The line pressure control unit calculates a line pressure command value serving as a command value for line pressure control based on the corrected primary required pressure and a secondary required pressure required for the secondary pulley, and controls the line pressure. A line pressure control device for a belt-type continuously variable transmission. A margin pressure setting part for setting the margin pressure is provided.
The said compensation part calculates the said primary required pressure after correction | amendment so that the steady-state deviation of the said primary required pressure with respect to the total pressure of the said actual primary pressure and a margin pressure may reduce. Line pressure control device for belt type continuously variable transmission. 3. The line pressure control in the belt type continuously variable transmission according to claim 2, wherein the margin pressure is set so as to include a maximum value of hydraulic pressure variation in the hydraulic system of the primary pressure and the line pressure. apparatus. The margin pressure is the sum of the actual primary pressure and the margin pressure even when the maximum change in the dynamic characteristics of the line pressure is in one calculation cycle of the corrected primary required pressure. 4. The line pressure control device for a belt-type continuously variable transmission according to claim 2, wherein the line pressure control device is set so as not to exceed the pressure. The compensation unit
5. The belt-type none according to claim 1, wherein the corrected primary required pressure is calculated using the corrected primary required pressure calculated previously as the primary required pressure in the current process. A line pressure control device for a step transmission. When the corrected primary required pressure is lower than the total pressure of the actual primary pressure and the margin pressure, the line pressure control unit sets the total pressure of the actual primary pressure and the margin pressure as the corrected primary required pressure. The line pressure control device for a belt-type continuously variable transmission according to any one of claims 2 to 5, further comprising a limit processing unit for outputting. 7. The line pressure control unit according to claim 1, wherein the line pressure control unit calculates the line pressure instruction value based on a higher hydraulic pressure value among the corrected primary required pressure and the secondary required pressure. A line pressure control device for a belt-type continuously variable transmission according to claim 1. A forward / reverse switching mechanism having a fastening element;
The line pressure control unit is configured to provide the line pressure instruction based on the highest primary pressure among the corrected primary required pressure, the secondary required pressure, and the fastening element pressure supplied to the fastening element of the forward / reverse switching mechanism. The line pressure control device for a belt type continuously variable transmission according to any one of claims 1 to 6, wherein a value is calculated.

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