JP2004125040A - Hydraulic control device for v-belt type continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure necessary hydraulic pressure even in a case where oil temperature is changed. <P>SOLUTION: An oil temperature correction quantity determining part 303 determines oil temperature correction quantity in accordance with oil temperature, and a line pressure correcting part 302 and a secondary pressure correcting part 304 correct target values for line pressure and secondary pressure based on the temperature correction quantity. A pressure control part 305 and a secondary pressure control part 306 conduct hydraulic pressure control based on the corrected target values for line pressure and secondary pressure. At low temperature, oil viscosity is set high. Necessary hydraulic pressure can thus be secured even in a case where response of the hydraulic pressure cannot be secured by similar direction of oil pressure to that at room temperature by proper direction of oil pressure in accordance with the oil temperature. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic control device that controls a line pressure and a secondary pressure according to an oil temperature in a V-belt type continuously variable transmission.
[0002]
[Prior art]
Conventionally, a V-belt type continuously variable transmission (hereinafter referred to as a belt CVT) has been known as an automatic transmission mounted on a vehicle. In this belt CVT, a V-belt is sandwiched between a primary pulley and a secondary pulley whose groove width is variably controlled based on hydraulic pressure, and power is transmitted by the contact frictional force.
Such a V-belt type continuously variable transmission obtains a thrust of a pulley according to an input torque and a gear ratio, and converts the thrust into a hydraulic pressure based on a predetermined value such as a pressure receiving area of a secondary pulley and a primary pulley. The hydraulic pressure is supplied to the transmission mechanism as a target line pressure.
[0003]
Further, such a V-belt type continuously variable transmission is provided with an oil pan, and the base oil of the line pressure is generated by sucking up the oil in the oil pan with an oil pump and pressurizing the oil. As such a V-belt type continuously variable transmission, there is one as described in JP-A-11-37237.
[0004]
[Problems to be solved by the invention]
In such a conventional V-belt type continuously variable transmission, the viscosity of the oil in the oil pan becomes high at a low temperature, and when the same oil pressure instruction is issued to the oil pump as at a normal temperature, the input torque increases. On the other hand, there was a problem that the rise in hydraulic pressure was delayed and the belt slipped.
[0005]
In view of the above problems, the present invention provides a hydraulic control device for a V-belt type continuously variable transmission that can secure a necessary hydraulic pressure and prevent belt slippage even when the oil viscosity is high at a low temperature. With the goal.
[0006]
[Means for Solving the Problems]
The present invention includes a primary pulley and a secondary pulley that sandwich a V-belt, generates a line pressure according to an operation state, generates a primary pressure and a secondary pressure based on the line pressure, and transmits the primary pressure to the primary pulley. In a V-belt continuously variable transmission in which secondary pressure is applied to a secondary pulley, an oil temperature sensor for detecting an oil temperature in the V-belt continuously variable transmission, and an oil corresponding to the oil temperature detected by the oil temperature sensor An oil temperature correction amount calculation unit that calculates the temperature correction amount as a multiplication coefficient, a secondary pressure calculation unit that calculates a secondary pressure target value according to the operating state, and a secondary pressure target value calculated by the secondary pressure calculation unit. A secondary pressure correction unit for performing correction, and controlling the secondary pressure based on the secondary pressure target value corrected by the secondary pressure correction unit. A secondary pressure control unit, and the secondary pressure correction unit corrects the secondary pressure target value calculated by the secondary pressure calculation unit based on the oil temperature correction amount calculated by the oil temperature correction amount calculation unit. It was taken.
[0007]
【The invention's effect】
According to the present invention, even when the oil temperature in the V-belt type continuously variable transmission is at a low temperature and the increase in the oil pressure is delayed, the secondary pressure control unit operates in accordance with the secondary pressure target value corrected in accordance with the oil temperature. Thus, the required hydraulic pressure can be secured under any oil temperature conditions.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to 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 transmission mechanism unit 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 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.
[0009]
The gear ratio of the transmission mechanism 5 and the contact frictional 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, ECU) 21 for controlling the engine 1 and exchanges information with each other. The CVT control unit 20 determines a gear ratio and a contact friction force from input torque information from the ECU 21, a throttle opening (TVO) from the throttle opening sensor 24, and the like.
[0010]
The primary pulley 10 of the transmission mechanism 5 is disposed at a position facing the fixed conical plate 10b, which rotates integrally with the input shaft, and the V-shaped pulley groove. It is composed of a movable conical plate 10a that can be displaced in the axial direction according to the hydraulic pressure (hereinafter, primary pressure) acting on the cylinder chamber 10c.
The secondary pulley 11 is disposed at a position facing 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. It is composed of a movable conical plate 11a that can be displaced in the axial direction according to the hydraulic pressure that acts (hereinafter, secondary pressure).
[0011]
The 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 displacing 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 to change the contact radius between the V-belt 12 and each of the pulleys 10, 11, the primary pulley 10 and the secondary pulley 11 can be continuously changed.
[0012]
As shown in FIG. 2, the hydraulic control unit 100 includes a pressure control valve 60 for controlling the line pressure, a shift control valve 30 for controlling the primary (Pri) pressure to the primary pulley cylinder chamber 10c, and a pressure control valve 30 for controlling the secondary pulley cylinder chamber 11c. The pressure reducing valve 61 for controlling the secondary (Sec) pressure is mainly configured.
The shift control valve 30 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 movable by a primary pulley 10 connected to the other end of the servo link 50. The feedback of the groove width, that is, the actual gear ratio is received from the conical plate 10a.
[0013]
The line pressure control system is constituted by a pressure regulating valve 60 provided with a solenoid 59 for regulating the pressure oil from the hydraulic pump 80, and is controlled in accordance with an operation state by a command (for example, a duty signal or the like) from the CVT control unit 20 in accordance with an operation state. Adjust to line pressure. The line pressure is supplied to a shift control valve 30 for controlling the primary pressure and a pressure reducing valve 61 provided with a solenoid 62 for controlling the secondary pressure.
[0014]
The gear ratio between the primary pulley 10 and the secondary pulley 11 is controlled by a step motor 40 driven according to a gear shift command signal from the CVT control unit 20, and gear shift control is performed according to the displacement of the servo link 50 responsive 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 shift control valve 30 is supplied to the primary pulley 10, and the groove width is variably controlled to set a predetermined gear ratio.
The shift control valve 30 supplies and discharges the hydraulic pressure to and from the primary pulley cylinder chamber 10c by the displacement of the spool 31, and adjusts the primary pressure so as to attain the target gear ratio commanded at the drive position of the step motor 40. When the shift is actually completed, the spool 31 is closed by receiving the displacement from the servo link 50.
[0015]
Here, the CVT control unit 20 includes a primary pulley speed sensor 26 for detecting the rotational speed of the primary pulley 10 of the transmission mechanism 5 and a secondary pulley speed sensor 27 for detecting the rotational speed (or vehicle speed) of the secondary pulley 11 in FIG. A signal from a secondary pressure sensor 28 for detecting a secondary pressure acting on a secondary pulley cylinder chamber 11c of the secondary pulley, a range signal from an inhibitor switch 23, and a throttle opening which is opened and closed by a driver's operation. By reading the throttle opening (TVO) from the throttle opening sensor 24 and the oil temperature of the transmission mechanism 5 detected by the temperature sensor 25, the speed ratio and the contact frictional force of the V-belt 12 are variably controlled.
[0016]
The CVT control unit 20 determines a target gear ratio in accordance with the vehicle speed and the throttle opening, and drives a 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 ratio, the oil temperature, and the like, and converts the calculated thrust into oil pressure.
[0017]
The pulley pressure control unit 202 determines the target value of the line pressure from the input torque information, the gear ratio based on the primary pulley rotation speed and the secondary pulley rotation speed, and the oil temperature, and drives the solenoid 59 of the pressure regulating valve 60 to control the line. The pressure is controlled, the target value of the secondary pressure is determined, and the solenoid 62 of the pressure reducing valve 61 is driven according to the detection value and the target value of the hydraulic pressure sensor 28 to control the secondary pressure by feedback control (closed loop control). .
[0018]
Next, the line pressure control and the secondary pressure control performed by the pulley pressure control unit 202 will be described with reference to FIG.
This is to correct the target values of the line pressure and the secondary pressure in a predetermined temperature range.
3, the line pressure calculation unit 300 and the secondary pressure calculation unit 301 calculate the target value of the line pressure and the target value of the secondary pressure according to the input torque information and the gear ratio as described above.
[0019]
The oil temperature correction amount calculation unit 303 calculates an oil temperature correction amount to be added to the line pressure and the secondary pressure based on the oil temperature in the transmission mechanism unit 5 detected by the temperature sensor 25. As shown in FIG. 4, when the oil temperature is -50 degrees, the oil temperature correction amount is set to 2.0, and the oil temperature correction amount is gradually increased from -50 degrees to -10 degrees. When the oil temperature is equal to or higher than -10 degrees, the value of the oil temperature correction amount is calculated to be 1.0.
[0020]
The line pressure correction unit 302 multiplies the target value of the line pressure calculated by the line pressure calculation unit 300 by the value of the oil temperature correction amount according to the oil temperature calculated by the oil temperature correction amount calculation unit 303. Make corrections. The line pressure control unit 305 controls the solenoid 59 based on the corrected target value of the line pressure corrected by the line pressure correction unit 302 to perform hydraulic control of the line pressure.
Similarly, in the secondary pressure correction unit 304, the value of the oil temperature correction amount corresponding to the oil temperature calculated by the oil temperature correction amount calculation unit 303 is compared with the target value of the secondary pressure calculated by the secondary pressure calculation unit 301. Multiply and correct. The secondary pressure control unit 306 controls the solenoid 62 based on the corrected secondary pressure target value corrected by the secondary pressure correction unit 304, and performs secondary pressure hydraulic control.
[0021]
As described above, the oil temperature correction amount calculation unit 303 calculates the oil temperature correction amount according to the oil temperature, and corrects the target values of the line pressure and the secondary pressure so that the line pressure and the secondary pressure can be reduced when the oil temperature is low. The oil pressure instruction can be increased.
[0022]
The present embodiment is configured as described above. Even when the viscosity of the oil increases at low temperature and the increase of the oil pressure is delayed at the same oil pressure instruction as at the normal temperature, the oil temperature correction amount calculating unit 303 determines the oil temperature according to the oil temperature. The correction amount is calculated, and the line pressure correction unit 302 and the secondary pressure correction unit 304 correct the target values of the line pressure and the secondary pressure based on the oil temperature correction amount, and the line pressure control unit 305 and the secondary pressure control unit The 306 controls the hydraulic pressure based on the corrected target values of the line pressure and the secondary pressure, so that the required hydraulic pressure can be secured.
[0023]
Further, by adding a correction according to the oil temperature to the line pressure and the secondary pressure, the thrust balance between the primary pulley and the secondary pulley can be maintained, and a predetermined gear ratio can be maintained.
Further, when the oil temperature is low, a high oil temperature correction amount is calculated, and the line pressure correction unit 302 and the secondary pressure correction unit 304 correct the hydraulic pressure target value to a value higher than that at normal temperature, so that the belt The required oil pressure that does not slip can be secured.
[0024]
Note that, in the above detailed description, the primary pressure and the line pressure have been described as being equal. However, the present invention is not limited to this, and by correcting the primary pressure and the secondary pressure, the primary pulley and the secondary pulley can be adjusted. Anything that can maintain the thrust balance may be used.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram showing a schematic configuration of a hydraulic control unit and a CVT control unit.
FIG. 3 is a diagram illustrating a flow of line pressure and secondary pressure control performed by a pulley pressure control unit.
FIG. 4 is a diagram illustrating a relationship between an oil temperature and an oil temperature correction amount.
[Explanation of symbols]
1 engine 3 belt CVT
5 Transmission mechanism unit 20 CVT control unit 21 ECU
25 Temperature sensor 59, 62 Solenoid 80 Hydraulic pump 100 Hydraulic control unit 202 Pulley pressure control unit 300 Line pressure calculation unit 301 Secondary pressure calculation unit 302 Line pressure correction unit 303 Oil temperature correction amount calculation unit 304 Secondary pressure correction unit 305 Line pressure control Unit 306 secondary pressure control unit

Claims (3)

A primary pulley and a secondary pulley for holding the V-belt, generating a line pressure according to an operation state, generating a primary pressure and a secondary pressure based on the line pressure, and transmitting the primary pressure to the primary pulley; In the V-belt continuously variable transmission in which
An oil temperature sensor for detecting an oil temperature in the V-belt type continuously variable transmission,
An oil temperature correction amount calculation unit that calculates an oil temperature correction amount according to the oil temperature detected by the oil temperature sensor as a multiplication coefficient,
A secondary pressure calculation unit that calculates a secondary pressure target value according to the operating state;
A secondary pressure correction unit that corrects the secondary pressure target value calculated by the secondary pressure calculation unit,
A secondary pressure control unit that controls the secondary pressure based on the secondary pressure target value corrected by the secondary pressure correction unit,
The secondary pressure correction unit corrects the secondary pressure target value calculated by the secondary pressure calculation unit based on the oil temperature correction amount calculated by the oil temperature correction amount calculation unit. Hydraulic control device for belt type continuously variable transmission. A primary pressure calculation unit that calculates a primary pressure target value according to the operating state;
A primary pressure correction unit that corrects the primary pressure target value calculated by the primary pressure calculation unit,
A primary pressure control unit that controls the line pressure based on the primary pressure target value corrected by the primary pressure correction unit,
The said primary pressure correction part corrects the primary pressure target value calculated by the said primary pressure calculation part based on the oil temperature correction amount calculated by the said oil temperature correction amount calculation part, The Claims characterized by the above-mentioned. Item 2. A hydraulic control device for a V-belt type continuously variable transmission according to item 1. The hydraulic pressure in the V-belt type continuously variable transmission according to claim 1 or 2, wherein a correction is applied to the primary pressure and the secondary pressure so that a thrust balance between the primary pulley and the secondary pulley is not changed by the correction. Control device.

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