JPS58214054A - Hydraulic controller for belt driving type stepless speed change gear - Google Patents

Abstract

PURPOSE:To secure torque transmission and improve the durability of a belt by detecting the slip of the belt from the change of the relation between the torque of an input shaft and the torque of an output shaft due to increase and decrease of a line pressure and controlling the line pressure to the min. value at which a prescribed torque transmission by the belt is secured. CONSTITUTION:When a belt 11 begins to slip in relation to discs 6, 7, 8, and 9, the amplitude ratio Aout/A-in between the amplitude Aout of the explosion cycle component (cycle of explosion in an engine. As the engine 1 is a 4-cylinder 1- cycle engine, two times explosion arises in one revolution of a crank shaft 2) of the torque of the output side discs 8 and 9 (output shaft 10) with respect to the amplitude A-in of the component of the explosion cycle of the torque of the input side discs 6 and 7 (=input shaft 5) sharply reduces. Therefore, Ain/Aout is detected from the input signal from torque sensors 29 and 30, and is controlled so that Ain/Aout becomes the value Pl1 which is a value obtained immediately before sharp reduction, following sharp reduction of the line pressure.

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.

Continuously variable transmission (hereinafter referred to as "C"
vT". ) is attracting attention. C like this
In a VT, the speed ratio and transmission torque need to be controlled, but a belt-driven CVT has a belt that is stretched between a pair of input-side disks and a pair of output-side disks, and has a belt that is connected to the transmission torque. The line pressure as servo oil pressure of the output side disk is controlled by the servo oil pressure of the input side disk, and the speed ratio is controlled by the servo oil pressure of the input side disk. The line pressure controlled by the pressure regulating valve is supplied to the hydraulic servo on the output side disc, but if the line pressure is too small compared to the appropriate value, the belt will slip against the disc, making torque transmission impossible, and the line pressure will decrease. If the diameter is too thick compared to the appropriate value, problems such as decreased durability of the CVT and drive loss of the oil pump will occur. Theoretically, if the friction coefficient of the belt contact surface is known, it is possible to optimally control the line pressure, but the friction coefficient changes depending on oil temperature, belt wear status, rotation speed, etc. Therefore, in the conventional belt-driven CVT hydraulic control device, the line pressure is set higher than the appropriate value in order to avoid belt slippage and ensure torque transmission throughout the entire operating period.

The purpose of the present invention is to control the line pressure so that it is maintained at the minimum value just before the belt starts to slide against the disk, and
It is an object of the present invention to provide a hydraulic control device for a drive type continuously variable transmission that can achieve both of ensuring torque transmission and improving the durability of a CVT.

To achieve this objective, according to the present invention, belt slippage is detected from changes in the relationship between input shaft torque and output shaft torque due to increases and decreases in line pressure, and predetermined torque transmission by the belt is ensured. Line pressure is controlled to the minimum value.

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

FIG. 1 is an overall schematic diagram. A crankshaft 2 of an engine 1 is connected to an input shaft 5 of a CVT 4 via a clutch 3. A pair of force input side disks 6 and 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 supported by the input shaft 5 so as to be movable relative to the input shaft 5. Fixed. A pair of output side disks 8°9 are also arranged facing each other, with one output side disk 8.
is fixed to the output shaft 10, 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 side disks 8.
The opposing surfaces of 9 are formed such that the distance between them increases radially outward. The belt 11 has a trapezoidal cross section and is stretched between the input disk 6.7 and the output disk 8.9. Pressure regulation (relief) valve 15
The oil path 1 is connected from the oil pan 16 to the oil pump 17.
Line pressure is generated in the oil passage 19 from the oil sent through the oil passage 8. Drain oil passage 20 for adjusting line pressure
The oil return 1-flow rate is controlled, and the oil passage 19 is connected to the hydraulic servo of the output side disc 9. Flow control valve 2
4 is connected to an oil passage 19, 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. When increasing the servo oil pressure of the input side disc 6, the oil passage 26 is connected to the oil passage 19 at 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 oil line 25. Torque sensors 29 and 30 detect the torque of input shaft 5 and output shaft 10, respectively, from changes in the direction of the magnetic field. , rotation angle sensors 31 and 32 detect the rotation speeds of the input side disk 7 and the output side disk 8, 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.

As the servo oil pressure of the output side disk 9 increases, the output side disk 9 is pressed toward the output side disk 8, and the contact position of the belt 11 on the disk 8.9 moves radially outward. . Line pressure is belt 11
is controlled so that it does not slip with respect to the disks 8 and 9.

In addition, 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 the contact position of the belt 11 on the disk 6.7 moves radially outward. This moves the CVT
A speed ratio of 4 is controlled. The servo oil pressure of the input side disk 6 and the servo oil pressure of the output side disk 9 are equal to 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, so a speed ratio of less than 1 is also possible. realizable.

The required horsepower is set as a function of the depression rate 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.

The basic idea of the present invention will be explained with reference to FIG. In Fig. 2, the horizontal axis is the line pressure, that is, the servo oil pressure of the output side disc 9, and the vertical axis is the input side disc 6.7 (-human power shaft 5).
) torque detonation frequency (detonation frequency in the engine).

Note that since the engine 1 is a four-cylinder, one-cycle engine, two explosions occur per 201 revolutions of the crankshaft. ) component amplitude Ain versus output side disks 8, 9 (output shaft 10)
The amplitude ratio A of the explosion frequency component of the torque Aout t
Out/Ain. Line pressure Pg >Pl'll
In the range of , even if the line pressure Pl decreases, the amplitude ratio Aout/
Ain is almost a constant value (!-=1), but when the line pressure Pl<pH, the belt 11 increases as the line pressure Pl decreases.
slips with respect to the disk 6.7.8.9, and the amplitude ratio Aou
t/Ain rapidly decreases, and when the line pressure is P/2, the bell) 11 completely slips against the disk 8.9. The present invention focuses on the fact that Aout/Ain rapidly decreases when the belt 11 starts to slip relative to the disks 6.7, 8.9, and detects Ain/Aout from the input signals of the torque sensors 29, 30. , A in/Ao
The pH value is controlled so that ut becomes the pH value just before it rapidly decreases as the line pressure decreases. More specifically, an increase or decrease in At n/Aout is checked by increasing or decreasing the line pressure, and the line pressure is controlled to the value immediately before Ain/Aout becomes equal to or less than a predetermined value.

FIG. 3 is a block diagram of an electronic control device according to the seven stomach concept explained in FIG. The bus 42 is an interface (I/
F) 43. Analog/digital converter (A/D)
44, Digital/analog converter (D/A) 45, C
PU46, RAM47, and ROM48 are connected to each other.

Input side rotation angle sensor 31 and output side rotation angle sensor 32
The output pulse of is sent to I/F 43. The outputs of the input side torque sensor 29 and the output side torque sensor 30 are passed through a bandpass filter 50 and an absolute value integrator 51 to an A/D converter.
Sent to 44. The output of the input side torque sensor 29 is also sent to the A/D via a low-pass filter 52. Pressure regulating valve 1
5 receives a signal from D/A 45, another output signal of D/A 45 controls the center frequency of bandpass filter 5o.

FIG. 4 is a block diagram of an embodiment of the present invention. In block 56, the DC component of the torque Tin of the input shaft 5
, Vout is calculated from the rotational speed Nin of the input shaft 5 and the rotational speed Nout of the output shaft 10.

Yout is the initial value of the input voltage of the pressure regulating valve amplifier 58, and Vout = K-〒an #Nin/Nou
It is calculated from the formula for t, and is set to a slightly higher value than the appropriate line pressure. However, K is a constant. The adder 57 is provided between the block 56 and the pressure regulating valve amplifier 58. The bandpass filter 50 calculates the explosion frequency ft (=2・Nin/60) from the rotational speed Nin of the input shaft 20 of the CVT 4.
Detects the CVT 4 input shaft 50 torque Tin.

Then, the explosion frequency component elements "in, T"out of the torque Tout of the output shaft 10 are selected and sent to block 62. In block 62, the absolute values I of T”in and T”out are determined.
Integrate T"inl, IT"outl over several cycles, and calculate the DC component Ai of IT"inl, IT"outl.
Detect n, Aout. In block 63, Aou
Amplitude ratio r between t and Ain (= Aout/Ain)
Detect. In block 64, the current amplitude ratio r(k)
The ratio of r(k) to the previous amplitude ratio r(k-1) -2,7o- is compared with the reference value a(k). That is, α=:(k-1)-a is calculated. Block 65 calculates the amount of correction (k) as a function of α. α>0. In other words, if 213≧a and the amplitude ratio Aout/Ain is approximately constant, -ΔV (however, ΔV is positive) is selected as the correction amount (k), and α is 0, That is, -5=signal-<a, and therefore, when the amplitude ratio Aout/Ain decreases rapidly, +ΔV is selected as the correction amount.

In block 66, the previous fee) variation amount Vfb
The current feedback amount fb(k) is calculated by adding ΔV to (k-1). In 57, Vout 10Vf
b(k) is calculated, and this sum is set as the input voltage V”out of the pressure regulating valve amplifier 58. In this way, r(k)7r(k−
1) is greater than or equal to a, the line pressure is reduced and r
If (k)7r(k-1) is less than a, i.e. if the amplitude ratio r decreases rapidly, the line pressure is increased, so that the line pressure is
The pH is controlled to be the value just before it starts to slip with respect to 8.9°.

FIG. 5 is a flowchart of a program according to the block diagram of FIG. In step 71, Tin, Ni
n, read Nout. In step 72, the initial value Vout of the input voltage of the pressure regulating valve amplifier 58 is set to Vout
= K# Calculated from Ttne Nin/Nout. In step 73, Tin, Tout, Nin
Load. Nin is the explosion frequency ft (-2・Nin/6
0 ).

In step 74, a bandpass filter is used to determine Tin, T
Extract the explosion frequency component element "in, T" out of out. In step 75, effective values Ain and Aout of T"in and T"out are calculated. Step 76
Now, the amplitude ratio r (-Aout/Ain) is calculated. In step 77, α is calculated from α-r(k)/r(k-1)-a. In step 78, α is compared with 0, and α≧
If it is 0, the process proceeds to step 82; if α<0, the process proceeds to step 83. Step 82 TehaVfb(k
-1) Substitute -ΔV into vfb(k). Step 83
Substitute it into Vfb(kl)+Δvwovfb(k).

In step 84, the input voltage V"o of the pressure regulating valve amplifier 58 is
ut is calculated from Vout + Vfb. However, Vf
b = vH, (k).

FIG. 6 is a diagram for explaining another basic idea of the present invention. If the line pressure is large enough, the bell) 11 is the disk 6.
．． 7.8.9, the explosion frequency components "in , T"ou
The phase difference of t is always maintained within a predetermined value. However, the line pressure decreased and the bell) 11 became disk 6.7,
8.9, the explosion frequency component "in" as shown in FIG. 6(b).

The phase difference of T out may exceed the range of ±180'. Therefore, the slippage of the belt 11 with respect to the disks 6.7, 8.9 is detected from the phase difference, and the line pressure is controlled to be the value immediately before the belt 11 starts slipping.

FIG. 7' is a block diagram of an embodiment of the invention according to the idea explained in FIG. Description of the same parts as in FIG. 4 will be omitted. In the phase difference detection circuit 91, T"in, T'o
Detect the phase difference θ of ut. Block 92 detects θ M times and stores it. In block 93, the maximum value θmax and the minimum value θmin are detected from among the M values of θ. In block 94, b-(θmax -0m1n) is assigned to α. In this way, when θmax-θmin is less than or equal to b, that is, when the phase difference is approximately constant over time,
-ΔV is selected in block 65 to reduce the line pressure eaves', and when the bell) 11 begins to slide relative to the disks 6.7, 8.9 and the change in phase difference increases, +ΔV is selected in block 65. line pressure is increased. As a result, the line pressure is controlled to a value just before the belt 11 begins to slide relative to the disks 6.7, 8.9.

In the electronic control device according to the block diagram of FIG. 7, a phase difference detection circuit 98 is provided between the bandpass filter 50 and the A/D 44 as shown in FIG.
The phase difference θ of out is A/D converted by the A/D 44.

FIG. 9 is a flowchart of a program according to the block diagram of FIG. The same parts as those in the flowchart of FIG. 5 are indicated by the same reference numerals, and the explanation will be omitted, and only the different parts will be explained. In step 103, 1 is assigned to i.

In step 105, the phase difference θ between Tin and Tout is detected. In step 106, i and M are compared and i4M
If so, proceed to step 107 and set i+1 as a new i, and if i=M, proceed to step 110. As a result, M pieces of θ are sampled. In step 110, M θ
The maximum value θmax and the minimum value θm1n( are calculated from
in) to α.

As described above, according to the present invention, by increasing or decreasing the line pressure, the minimum value of the line pressure that can ensure appropriate torque transmission is detected, and the line pressure is controlled to become this minimum value. Therefore, while ensuring torque transmission, it is also possible to prevent deterioration in the durability of the CVT and drive loss of the oil pump.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the entire embodiment of the present invention, FIG. 2 is a diagram for explaining the basic idea of the first embodiment of the present invention, and FIG. 3 is an electronic diagram of the first embodiment. A block diagram of the control device, FIG. 4 is a block diagram of the first embodiment, FIG. 5 is a flowchart of a program according to the block diagram of FIG. 4, and FIG. 6 is a basic diagram of the second embodiment of the present invention. 7 is a block diagram of the second embodiment, FIG. 8 is a block diagram of the electronic control unit in the second embodiment, and FIG. 9 is a diagram for explaining the idea.
The figure is a flowchart of a program according to the block diagram of FIG. 4...CVT, 5...Input shaft, 6,7...Input side disk, 8,9...Output side disk, 1o...
Output shaft, '11-... Belt, 15... Pressure regulating valve, 29
．． 30...torque sensor. Patent applicant: Toyota Motor Corporation Figure 1 Figure 2 PI3 pH line pressure P1

Claims (1)

[Scope of Claims] 1. A belt-driven continuously variable transmission is provided with a belt that can be hung between a pair of input-side disks and a pair of output-side disks, and the output side In a hydraulic control system for a belt-driven continuously variable transmission, in which the line pressure as the servo oil pressure of the disk is controlled and the speed ratio is controlled by the servo oil pressure of the input side disk, the torque of the input shaft and the output shaft are controlled by increases and decreases in line pressure. The hydraulic pressure of a belt-driven continuously variable transmission is characterized in that belt slippage is detected from changes in the relationship with torque, and line pressure is controlled to the minimum value that ensures a specified torque transmission by the belt. Control device. 2. Calculate the amplitude ratio of the explosion frequency component of the torque of the output side disk to the explosion frequency component as a vibration component corresponding to the engine explosion interval of the torque of the input side disk, and calculate the current (9) amplitude ratio to the previous amplitude ratio. The first aspect of the present invention is characterized in that the line pressure is decreased when the ratio of Hydraulic control device as described in section. 3. If the change in the phase difference of the explosion frequency component of the torque of the output side disk with respect to the explosion frequency component of the torque of the input side disk is less than the second predetermined value, reduce the line pressure;
2. The hydraulic control device according to claim 1, wherein the line pressure is increased when the change in the phase difference is larger than a second predetermined value.