JPS5919755A - Line pressure controller for belt drive type stepless speed change gear - Google Patents

Abstract

PURPOSE:To improve the accuracy in controlling the line pressure of a CVT, by feed-back controlling the line pressure so as to reduce it when an actual value thereof is higher than a target value and raise it when the actual value is lower than the target value. CONSTITUTION:An amplifier 50 for a pressure-regulating valve 15 generates an output electric current which is a linear function of an input voltage Vout, and feeds the current to the valve 15. An output-side servo oil pressure Pout is detected by an oil pressure sensor 34, an output from which is amplified by an amplifier 51, and is fed to an adding point 53a through a processing circuit 52. The result of calculation at the adding point 53a is fed to an adding point 55a through a feed-back element 54a. The result of calculation at the adding point 55a is fed to the amplifier 50, and an input voltage to the amplifier 50 is varied in accordance with Vout*-Vout, based on Vout. Accordingly, when a target line pressure Pl* is higher than the actual line pressure Pl, the return flow rate through the valve 15 is reduced, thereby raising the line pressure Pl, and when the target line pressure Pl* is lower than the actual line pressure Pl, the flow rate is increased, thereby lowering the line pressure Pl.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device for a belt-driven continuously variable transmission used, for example, as a power transmission device for an automobile.

In the earlier Japanese Patent Application No. 57-40747, the present applicant
An automobile power transmission device using a continuously variable transmission (hereinafter referred to as "CVT") has been disclosed. In this prior application, the CVT includes a belt that is stretched between a pair of input side disks and a pair of output side disks, and the line pressure as servo oil pressure of the output side disk is controlled in relation to the transmitted torque.
The speed ratio is controlled by the servo oil pressure of the input side Tinuku. The line pressure is increased or decreased by controlling the return flow rate in the pressure regulating valve, and is indirectly controlled by the CPU or the output voltage to the pressure regulating valve amplifier, but in the earlier application, the line pressure is
Since it was an open-loop control, it was greatly affected by variations in the characteristics of the pressure regulating valve and disturbances, resulting in low control accuracy.

An object of the present invention is to provide a belt-driven CVT line pressure control device that can improve the control accuracy of CVT line pressure.

To achieve this objective, the belt-driven CVT of the present invention
According to the method, line pressure is feedback-controlled so that when the actual value of line pressure is greater than the target value, the line pressure is decreased, and when the actual value of line pressure is less than the target value, the line pressure is increased. do.

The invention will now be described with reference to the drawings.

First, the present invention is applied to the entire vehicle power system.
This will be explained in the figure. A crankshaft 2 of an engine 1 is connected to an input shaft 5 of a CVT 4 via a clutch 3. 1
The pair of input end disks 6°7 are arranged opposite each other,
One input side disk 6 is supported by the input shaft 5 so as to be relatively movable in the axial direction, and the other input side disk 7 is supported by the input shaft 5.
Fixed. A pair of output side disks 8°9 are also arranged opposite to each other, one output side tinuk 8 is fixed to the output shaft 10, and the other output side disk 9 is fixed to the output shaft 10.
is supported for relative movement in the axial direction. The opposing surfaces of the pair of input side disks 6.degree. 7 and output side disks 8, 9 are formed such that the distance between them increases radially outward. The belt 11 has a trapezoidal cross section and includes an input side disk 6.7 and output side disks 8, 9.
It is served in between. The pressure regulating (relief) valve 15 receives oil from an oil pan 16 by an oil pump 17 through an oil passage 18 and generates line pressure in an oil passage 19 . In order to adjust the line pressure, the flow rate of oil returned to the drain oil passage 20 is controlled, and the oil passage 19 is connected to an output side disk 90 pressure servo. The flow rate control valve 24 includes an oil passage 19,
It is connected to a drain oil passage 25 and an oil passage 26, and the oil passage 26 is connected to a hydraulic servo of the input side disk 6. If the servo oil pressure of the input side disc 6 is to be increased, the oil passage 26 is connected to path 41''9 in the flow control valve 24, and if the servo oil pressure of the input side disc 6 is to be decreased, the oil passage 26 is connected to the drain. Connect to oil line 25. The torque sensor 29 detects the torque Tin of the input shaft 5 from changes in the direction of the magnetic field. The rotation angle sensors 31 and 32 detect the rotational speed Nin of the input side disk 7 and the output side disk 8.
, detect Nout. The oil pressure sensor 34 detects the output side servo oil pressure Pout (-line pressure Pl). The throttle actuator 35 controls the opening degree of the intake system throttle valve, and the accelerator pedal sensor 36 detects the amount of depression of the accelerator pedal 38 near the driver's seat 37.

As the servo oil pressure of the output side disk 9 increases, the output side disk 9 is pushed toward the output side disk 8, and accordingly, the contact position of the belt II on the disks 8, 9 moves radially outward. . The line pressure is controlled so that the belt 11 does not slip against the disc 8.9. Further, as the servo oil pressure of the input side disk 6 increases, the input side disk 6 is pressed toward the input side disk 7.
Along with this, the contact position of belt 1 on Tinuku 6.7 moves radially outward, and this causes CVT 4 to move outward in the radial direction.
The speed ratio of is controlled. Input 1 rule Task 6 servo oil pressure Pin ≦ Output 1 rule TINUK 9 servo oil pressure Pout
However, the pressure receiving area A of the hydraulic servo of the input end disk 6
in≧Pressure receiving area Aou of hydraulic servo of output side Tinuku 9
t, it is possible to realize a speed ratio of less than 1.

The required horsepower is set as a function of the amount of depression of the accelerator pedal 38, and the target torque and target rotational speed of the engine are set as functions of the required horsepower. The opening degree of the intake system throttle valve is controlled as a function of the target torque, and the speed ratio of the CVT 4 is controlled as a function of the target rotational speed. Engine torque T
The details of the control of e and rotational speed Ne can be found in the above-mentioned Japanese Patent Application No. 57.
-40747.

FIG. 2 is a block diagram of a first embodiment of the present invention. In this embodiment, deviation calculation for feedback control is performed in an analog circuit 42a. The target line pressure Pl, that is, the target value Pout'' of the output side servo oil pressure Pout is set in the microcomputer 43a. In block 44, the initial value Vout of the pressure voltage of the pressure regulating valve amplifier 500 Å is set as a function f (Pout') of pout''. Calculated as Pout” and Vout, are D/
A (digital/analog converter) 45a.

D/A conversion is performed at 46a. Amplifier 5 for pressure regulating valve
0 generates an output current that is a linear function of its input voltage Vout, and sends the output current to the pressure regulating valve 15.

The pressure regulating valve 15 fully controls the return flow rate in relation to its input current, and the output side servo oil pressure Pout of the CVT 4 is controlled by the pressure regulating valve 15.
It is a linear function of the 0 input terminal. Output side servo ura) −j−
Pout is detected by the oil pressure sensor 34, and the output of the oil pressure sensor 34 is amplified by the amplifier 51 and sent to the summing point 53a via the processing circuit 52.

The processing circuit 52 outputs the D/A 45 at the summing point 53a.
It consists of an amplifier for matching the output of the amplifier 51 with the output of the amplifier 51. At the addition point 53a, it may be the manual input Pout from the D/A 45a, or the input Pout from the processing circuit 52.
Subtract. The calculation result at the summing point 53a is sent to the summing point 55a via the feedback element 54a.

Feedback element 54a consists of an amplifier for taking the input from summing point 53a at summing point 55a and matching it with the input from /A46. Addition point 5
5a, the input from the feedback element 54a and the D/A
46a. The calculation result at the addition point 55a is sent to the pressure regulating valve amplifier 50. As a result, the input voltage of the pressure regulating valve amplifier 50 is Vout'-Vout based on Vout. Therefore, when the target line pressure Pl is larger than the actual line pressure Pl, the return flow rate at the pressure regulating valve 15 decreases and the line pressure Pl increases, and the target line pressure Pl+ is larger than the actual line pressure Pl. When the line pressure Pl is smaller than the line pressure Pl, the return flow rate in the pressure regulating valve 15 increases and the line pressure Pl decreases.

FIG. 3 is a block diagram of another embodiment of the invention. In this embodiment, deviation calculation for feedback control is performed within the microcomputer 43b. Identical blocks are indicated with the same symbols as in FIG. 2, and modified corresponding blocks are indicated with only the same numbers in the symbols.

FIG. 4 is a flowchart of an algorithm according to the present invention. In step 61, a target value Pout''(=pl'') of the output side servo oil pressure Pout is calculated.

In step 62, the initial value Vout of the input terminal of the pressure regulating valve amplifier 500 is calculated. In step 63, the output side servo oil pressure Pout is read as an actual value. In step 64, the target value Pout - the actual value Pout is shifted from the deviation ΔP. In step 65, the input terminal V of the pressure regulating valve amplifier 5o
Shift the out correction amount Δ■ to K・ΔP. however.

K is a constant. In step 66, Vout +ΔVou
Assign t to Vout. In step 67, Vout is output to the pressure regulating valve amplifier 50. Step 68
Determine whether or not ut' has been changed, and if so, proceed to step 61.
If there is none, the process returns to step 63. Thus, fI
P out is feedback-controlled in relation to the im difference Pout' - Pout.

As described above, according to the present invention, since the line pressure is feedback-controlled, it is possible to accurately control the line pressure while avoiding variations in characteristics of elements such as pressure regulating valves and influences from disturbances. Also, since the line pressure is detected incorrectly,
Abnormalities in hydraulic systems such as pressure regulating valves should be detected promptly.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of a vehicle power transmission device to which the present invention is applied, FIGS. 2 and 3 are block diagrams of embodiments of the present invention, and FIG. 4 is a flowchart of an algorithm according to the present invention. be. 4...CVT, 6,7...Input end disk, 8,9...
...Output side disk, 11-.Belt, 15..Pressure regulating valve, 34./11] Pressure sensor.

Claims (1)

[Claims] A belt-driven continuously variable transmission has a pair of input side TINUK and one
Equipped with a belt that can be hung between the pair of output side disks,
The line pressure as servo oil pressure of the output side disk is controlled in relation to the transmitted torque, and the speed ratio is controlled by the servo oil pressure of the input end disk.In the hydraulic control system of a belt-driven continuously variable transmission, the actual line pressure is Feedback control of the line pressure is performed to reduce the line pressure when the line pressure is greater than the target value, and to increase the line pressure when the actual value of the line pressure is less than the target value. Line pressure control device for drive-type continuously variable transmission.