JPS5929863A - Line pressure control system for belt driven stepless speed change gear - Google Patents

Abstract

PURPOSE:To improve the durability of a belt by conducting the optimum line pressure control during the period when the optimum line pressure control is feasible that controls the line pressure at a value near the slipping point of belt, calculting the required factor, and then, controlling the line pressure base on said factor at the period when the optimum line pressure control is not conducted. CONSTITUTION:A line pressure control area is divided into an optimum line pressure control conducting area A and non-conducting area B. In the area A, the optimum line pressure control is conducted while calculating a required factor K*. The initial value of the optimum line pressure control is also calculated based on the K*. Therefore, the line pressure in the area B and the line pressure as the initial value can be set at small values, improving the durability of a belt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line pressure control device for a continuously variable transmission used in a vehicle power transmission device.

The present applicant previously disclosed a power transmission device for a vehicle using a continuously variable transmission (hereinafter referred to as ``cV TJ'') in Japanese Patent Application No. 57-40747, etc. Belt drive type C
If the servo oil pressure, or line pressure, of the output disk of the VT is too low, the belt will slip and torque transmission will be impossible; if it is too high, the durability of the belt will be affected.
The present applicant has disclosed in Japanese Patent Application No. 57-96122 a line pressure control device that can control the line pressure to a value almost immediately before the belt begins to slip. However, this patent application 1986-961
The line pressure control device No. 22 has the following problems.

(1) There are operating regions where the data signal for detecting the limit line pressure cannot be obtained, or where part of the data signal is unreliable. For example, when the engine rotational speed is high, the fluctuation in the engine output torque is small, and the reliability of the engine output torque data decreases.

(2) For safety, the initial value of line pressure is based on oil temperature, cv
'r□ must always be set at a fairly high value in consideration of wear, changes over time, etc.

An object of the present invention is to reduce the line pressure to the lowest possible value even in areas where it is difficult to detect the slipping point of the belt and it is impossible to control the line pressure to an optimum value. It is an object of the present invention to provide a line pressure control device for a belt-driven continuously variable transmission that can set the pressure to a small value.

The present invention will be described in detail with reference to the drawings.

First, to explain the entire continuously variable transmission vehicle power transmission system in FIG. 1, the crankshaft 2 of the engine 1 is connected to the clutch 3
It is connected to the input shaft 5 of the CVT 4 via. A pair of input side disks 6 7 are arranged opposite to 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 fixed to the input shaft 5. has been done. A pair of output side disks 8°9 are also arranged facing each other, and one output side disk 8 is connected to the output shaft 1.
0, and the other output side disk 9 is supported by the output shaft 10 so as to be relatively movable in the axial direction. A pair of input side disks 6゜7 and output fIll disks 8,90
The opposing surfaces are formed such that the distance between them increases outward in the -radial direction. The belt 11 has a trapezoidal cross section and is stretched between the input disk 6.7 and the output disks 8, 9. A pressure regulating (relief) valve 15 is connected to an oil passage 18 by an oil pump 17 from an oil pan 16.
Line pressure is generated in the oil passage 19 from the oil sent through the oil passage. In order to adjust the line pressure, the flow rate of oil returned to the drain oil path 20 is controlled, and the oil path 19 is connected to the hydraulic servo of the output side disc 9.
is connected to the oil passage 19, the drain oil passage 25, and the oil passage 26, and the oil passage 25 is connected to the hydraulic servo of the input side disk 6. When increasing the servo oil pressure of the input side disc 6, the oil passage 26 is connected to the oil passage 19 in the flow control valve 24, and when decreasing the servo oil pressure of the input side disc 6, the oil passage 26 is connected to the oil passage 19. Connect to 25.

Torque pins 29 and 30 detect the torque of the input shaft 5 and the output shaft 1o, respectively, from changes in the direction of the magnetic field. Rotation angle sensors 31 and 32 detect the rotational speeds of the input-side disk 7 and the output-side disk 80, respectively. 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.

Output side due to increase in servo oil pressure of output side disc 9]
The disk 9 is pressed toward the output side disk 8, and the contact position of the belt 11 on the disks 8, 9 moves radially outward. Line pressure is belt 1
1 is controlled so that it does not slip with respect to the disk 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, and as a result, the belt 11 on the disk 6.7
The contact position of moves radially outwards, which causes the CV
The speed ratio of T4 is controlled.

The servo oil pressure of the input side disk 6 ≦ the servo oil pressure of the output side disk 9, but since the pressure receiving area of the hydraulic servo of the input side disk 6 ≧ the pressure receiving area of the hydraulic servo of the output side disk 9, a speed ratio of less than 1 is also possible. It will come true.

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 CV T 4 is controlled as a function of the target rotational speed. The details of the control of the output torque and rotational speed of the engine are described in the above-mentioned patent application 1982-
No. 40747 etc. were referred to (・.

In the present invention, the line pressure control area is divided into an optimal line pressure control implementation area A and an optimal line pressure control non-execution area B, as shown in FIG. Region A is the input side rotational speed Ni of CV T4
n (=engine rotation speed Ne) 2nd input side torque Tin
(=engine quantity Katorque Te) and input data are both defined as reliable intervals.

FIG. 3 is a flowchart of the algorithm of the present invention. In step 51, the first initial value of K is I<
Read 0. In step 52, KO* is assigned to NI*. K*-KO* is obtained only once at the beginning, and thereafter I(" is determined by the optimum line pressure control routine in step 56. In step 53, the basic value of the voltage sent to the amplifier for the pressure regulating valve 24 is determined. Calculate vout*.

Vout is expressed by the following equation.

Vout*= K*-out -to*・〒in/e=K-f(e,Tin) However, Tout: CVT4 output side torque (not including vibration component) Tin: CVT4 input side torque (vibration e: CV', I'4 speed ratio Step 54 is the actual value of the voltage Vout sent to the amplifier for the pressure regulating valve 24
= K-Vout*. However, K is a value larger than 1, and by making the line pressure Pl a little thicker than the appropriate value,
to ensure that slippage is avoided. As Vout increases, the amount of drain in the pressure regulating valve 15 decreases, and the line pressure Pl is expressed by the following equation.

Pl = Kl - Vout + K where Kl and 2 are constants.

In step 55, the CVT is
4 is in the region A of FIG.
If it is in area B, the process returns to step 53.

Details of the optimal line pressure control in step 56 will be explained with reference to FIG.

In step 6o in FIG. 4, the input torque Tin and output torque Tout of the CVT 4 are read.

In step 61, a bandpass filter is used to filter Tin.
, Tout, the component elements in and Tout corresponding to the explosion frequency of the engine combustion chamber are extracted. In step 62, the execution values Ain and Aout of Tin and Tout are detected. In step 63, r = Aout / Ain
Calculate.

In step 64, α=r(k)/r(k−
1) Calculate -a. However, r(k) is at step 63
r and r(k-1) obtained by the current execution of step 63 are constants, and r and a obtained by the previous execution of step 63 are constants. In step 65, α is compared with 0. If α20, the process proceeds to step 7o, and if α<0, the process proceeds to step 71. FIG. 5 shows the relationship between line pressure Pl (-CVT4 output side servo oil pressure) and amplitude ratio Aout/Ain,
When line pressure Pl becomes smaller than P71, Aout/Ai
It can be seen that n rapidly decreases and slip occurs from Pl <'P12. Therefore, when α is 20, it is determined that Pl>pH, and the line pressure Pl is decreased by a predetermined amount, and when α is 0, it is determined that Pl<Pl+, and the line pressure Pl is increased by a predetermined amount.

That is, in step 70, Vfb is decreased by -ΔV. Nao vfb (k) is the current correction amount, Vfb (k-
1) is the previous correction amount. In step 71, *-V
Calculate out/f(e, Tin). By executing the optimum line pressure control routine, the line pressure Pl will eventually come close to pH, so by executing step 71, Pl
”: PA' Calculated at 10 o'clock. This * is C
Since it will be used in step 53 in FIG. 3 when VT4 next enters region B or during acceleration/deceleration, the line pressure Pl in region B and the line pressure Pl as the initial value should be appropriate values that are not too thick. controlled by. In step 72, Vfb is increased by ΔV.

In step 73, Vout +Vfb is substituted for Vout, and Vout is outputted to the amplifier of the pressure regulating valve 15 as a control voltage. In step 74, it is determined whether or not it is acceleration/deceleration,
If the vehicle is in an acceleration/deceleration state, step 53 in Figure 3
If the vehicle is maintained in a steady state, the process returns to step 60 to continue optimum line pressure control.

FIG. 6 is a block diagram of the present invention. The band pass filter 78 has an input side torque Tin and an output side torque Tout.
Extract the explosion frequency components in and Tout of . The explosion frequency can be detected from Nin.

The execution values Ain and Aout are calculated. block 80
, 81 correspond to steps 63 and 64, respectively, and r
, α is calculated. Block 82 corresponds to steps 70, 72
Corresponding to α〉0. In relation to α〈0, Δ■ certain view is −
Select Δ■−. Block 83 corresponds to step 73 and corrects Vfb. Block 88 corresponds to step 71, and when Pl is sufficiently close to the limit value pH, 1<”=
Calculate Vout/f (Tin, e). Block 9
0 corresponds to steps 53 and 54, and Vout is calculated. At addition point 91, Vout + Vfb is Vou
Substitute into t. In region B, addition from block 88 at addition point 91 is stopped, and Vou of block 90 is
t is sent as is to the control amplifier 92. Vout thus calculated is sent to the pressure regulating valve control amplifier 92, and the line pressure Pl is controlled.

FIG. 7 is a block diagram of the electronic control device.

CPU 100, It, AMIOI, ROM 10
2, ■/F (Interface) 103, A/I) (
The analog/digital converter) +04 and the D/A (digital/analog converter) 105 are connected to each other by a bus 106.The output pulses of the input side rotation angle sensor 31 and the output side rotation angle sensor 32 are The analog outputs of the input side torque sensor 29 and the output side torque sensor 30 are sent to the integrator I08 via the bandpass filter 78, and Ain and Aout are A/
A/D conversion is performed at DI 04. The analog output of the input side torque sensor 29 is sent to a low-pass filter 109, and the DC component 1'1n of Tin is A/D converted by an A/D 104. Tin is used when detecting Vout* in step 53 of FIG. The center frequency of the bandpass filter 78 is tuned to the detonation frequency, and the detonation frequency is Nin
It may also be detected. The output Vout of the D/A is sent to the pressure regulating valve control amplifier 92 to control the line pressure Pl.

FIG. 8 shows another principle for detecting belt slip points. T
in and '1゛0 old explosion frequency component element 1 stave.

Tout maintains a constant phase difference when the line pressure Pl is sufficiently high (a), but when the belt 1 begins to slip (b), the phase difference changes beyond ±180°.

Therefore, by detecting the phase difference between Tin and Tou, the slipping point of the belt 11 can be detected. The algorithm, block diagram, and modified portions of the block diagram of the electronic control device of an embodiment utilizing this principle are shown in FIGS. 9, 10, and 11, respectively.

In FIG. 9, step 114 is set to 1-1. In step 115, the phase difference θ between Tin and Tout is detected. In step 116, 1 is compared with a predetermined value M, and 1
˜M, the process proceeds to step 117, where 111 is substituted for 1, and the process proceeds to step 6o. Further, if I=M, the process advances to step 117. In this way, θ is sampled over a predetermined period. In step 117, the maximum value θma of θ
x and the minimum value θ1η1n are calculated. Step 118
Now, a-(θmax-〇m1n) is substituted for α. When the belt 11 approaches the slipping point, θmax-θmin increases and becomes α<0, and if the line pressure Pl is sufficiently high, θmax-θmin becomes small and becomes α>0.

In FIG. 10, θ is detected in the phase difference detection circuit 121, and in block 122, θ is detected and recorded M times.

In block 123, θmax and θmin are detected from M θ. In block 124 α=a−(θmax
-0m1n).

In FIG. 11, a phase difference detection circuit 121 is provided between the bandpass filter 78 and the A/D 104.

FIG. 12 shows another principle for detecting the slip point of Bell) 11. As the line pressure Pl decreases, the fluctuation component of Tout causes resonance at a certain frequency U.

The amplitude of the resonance component out* reaches its peak value just before slipping, as shown in FIG. Therefore Tou
By detecting t, the slip point of the belt 11 can be detected. The algorithm, block diagram, and modified portions of the block diagram of the electronic control unit of the embodiment using Tout* are shown in FIGS. 13, 14, and 15, respectively.

In FIG. 13, 'rout' is read in step 129. In step 130, a bandpass filter is used to
Extract the resonance frequency component out* of u t. In step 131, the amplitude Aout of Tout* is calculated. In step 132, α= Aout(k) −Aout
(k −1)−α is calculated.

In the Nofrock diagram of FIG. 14, the band pass filter 135
Tout is extracted, and the integrator 136 extracts Aou
L is calculated, and α=Aout(k)−
Calculate Aout (k-1)-a.

In the block diagram of FIG.
/T)+04, and the center frequency of the bandpass filter 135 is set to the aforementioned common frequency.

FIG. 16 shows another principle for detecting slip points of the belt 11. As shown in FIG. 16, the transmission efficiency η(
=output/input) reaches its peak just before slipping as the line pressure Pl decreases. Figures 17, 18 and 19
The figure shows an algorithm using this principle, a block diagram,
and shows a changed part of the block diagram of the electronic control unit.

In the flowchart of FIG. 17, step 140 (・
and read Tire, Tout, Nin, and Nout. In step 141, the intestine n is filtered by a low-pass filter.

Extract the DC component in, Tout of Tout. In step 142, the transmission efficiency r) = Tout-N
Calculate out/Tin・Nin. Step 14
In step 3, α=η(k)−η(k−1)−a is calculated.

In the block diagram of FIG. 18, the low-pass filter 146 extracts the DC components in and Tout.
Block 147 calculates η, and block 148 calculates α.

In the block diagram of FIG. 19, a low-pass filter 146 is provided between the Dorxe/S 29, 30 and the A/D 104.

FIG. 20 shows another principle for detecting slippage of the belt 11. The relationship between the input side servo oil pressure Pin and the output side servo oil pressure Pout of the CVT4 appears as shown by the solid line in Fig. 20 with respect to the line of Pin = Sr・Pout, and Pi
When n becomes close to the Pin=5r-Pout line, the belt 11 will slip. Sr is expressed by the following formula.

Sr = (Aout4in)/(Ain・ψout)
However, Ain: Pressure receiving area of the CVT input side servo AO Old: Pressure receiving area of the CVT output side servo ψ1n:
Wrapping angle ψout of the belt on the input side disk: Wrapping angle of the belt on the output side disk Figure 21, 2nd
2 and 23 show an algorithm, a block diagram, and a modified part of the electronic control device of an embodiment that utilizes this principle.

In the flowchart of FIG. 21, in step 153, Pin and Pout are read. In step 154, the DC component of Pin and Pout is -5 by a low-pass filter.
Calculate r-Pout-a.

In the block diagram of FIG. 22, the low-pass filter 58 converts the DC components of Pin and Pout into
is extracted and α is calculated in block 159.

In the block diagram of FIG. 23, an input side oil pressure sensor 162, an output side oil pressure sensor 163, and an input pressure sensor 1
The output of 9 is passed through a low-pass filter 158 to Al1)1
Sent to 40. Tin is used in step 53 in Figure 3 (
・Can be done.

According to the present invention, optimal line pressure control is carried out during a period in which optimal line pressure control is possible, in which line pressure is controlled to a value near the belt slipping point, and the predetermined coefficient I<*
is calculated, and then the line pressure is controlled based on K during the non-implementation period of optimal line pressure control. Further, the initial value of the optimum line pressure control is also calculated based on K of and. Therefore, the line pressure during the non-execution period and the line pressure as an initial value can be set to a small value, and the durability of the belt can be improved.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a continuously variable transmission vehicle power transmission system to which the present invention is applied, FIG. 2 is a diagram showing implementation areas and non-implementation areas of optimal line pressure control in the invention, and FIG. Flowchart of the algorithm of the present invention, FIG. 4 is a detailed flowchart of the optimum line pressure control routine, FIG. 5 is a diagram for explaining the principle of detecting the belt slip point, and FIG.
7 are a block diagram of an embodiment using the principle of FIG. 5, a block diagram of an electronic control device, and FIG.
a), (b) are diagrams for explaining other principles of detecting belt slip points, Figures 9, 10, and 11.
The figure shows a flowchart, a block diagram, and a block diagram of the electronic control device of only the modified part of the embodiment using the principle of FIG. 8, and FIG. 13, 14, and 15 are a flowchart, a block diagram, and a block diagram of the electronic control device of the embodiment using the principle of FIG. 12, and FIG. 16 is a block diagram of the belt. Figures 17, 18, and g+c+ diagrams for explaining other principles for detecting slipping points are flowcharts, block diagrams, and electronic diagrams of only modified parts of the embodiment using the principle of Figure 16. A block diagram of the control device, FIG. 20 is a diagram for explaining another principle of detecting belt slip points, FIG.
Figures 2 and 23 are lJ using the principle of Figure 20.
FIG. 7 is a flowchart, a block diagram, and a block diagram of an electronic control device of only the changed portions of the t+ example. FIG. 4...CTV, 6,7...Input side disk, 8,9...
... Output side disk, 11... Belt, 15... Pressure regulating valve, 29... Input side torque sensor, 31, 32...
Rotation angle sensor. Representative Patent Attorney Osamu Nakahei;・,-2,・
'C+,,'a,' Figure 1 Figure 2

Claims (1)

[Claims] The rotation of the input side disk is transmitted to the output side disk via the belt, the hydraulic servo line pressure of the output side disk is supplied, and the line pressure is controlled to be reduced to a level that does not interfere with torque transmission. In a line pressure control device for a belt-driven continuously variable transmission, the operating period of the continuously variable transmission is divided into a period in which line pressure reduction control is possible and a period in which it is not possible, and in the possible period, line pressure reduction control is performed. At the same time, calculate I from the following formula, Vo old in the possible period and Vout as the initial value
A line pressure control device for a belt-driven continuously variable transmission, characterized in that Vout*-*-"Fo.tVout=K-Vout" is calculated from the following equation: A constant thicker than 1.