JPS58191358A - Oil hydraulic controller of belt type stepless speed changer - Google Patents

Abstract

PURPOSE:To properly control line pressure and a flow amount, by relating output voltage to a pressure control valve to output voltage to a flow control valve to perform correction and cancelling an influence of the flow amount to the line pressure. CONSTITUTION:In a step 66, a depressive amount Xacc of an accelerator pedal is detected to calculate target output horsepower PS' corresponding to the Xacc. In a step 67, a target input rotary speed N' in is calculated from the horsepower PS'. In a step 68, output voltage Vout to a pressure control valve is standardized, that is, m=Vout/Vmout (output voltage to the pressure control valve generating standard line pressure as a reference value) is calculated. In a step 69, output voltage Vin to a flow control valve is calculated from an expression 6. In a step 70, an outut rotary speed Nout of engine output torque Te is read. In a step 71, Vout is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device for a belt type continuously variable transmission used as a power transmission device for a vehicle.

The present applicant has previously provided a power transmission system for a vehicle that can control the operation of an internal combustion engine at a minimum fuel efficiency over the entire operating range using a continuously variable transmission. In the vehicle power transmission device, a belt-type continuously variable transmission includes a pair of input side disks, a pair of output side disks, and a belt that is hung between the input side disk and the output side disk to transmit power. The pressure control valve controls the pressure supplied as line pressure to the hydraulic servo of the output side disk by controlling the release amount of the hydraulic medium supplied from the hydraulic pump, and the flow control valve controls the hydraulic pressure of the input side disk. Controls the minimum flow rate of hydraulic medium at a pressure above the line pressure to the servo and the discharge flow rate of the hydraulic medium from the input side disc to the maximum pressure below the line pressure, and is related to the transmission torque of the continuously variable transmission. The line pressure is controlled by changing the output voltage Vout to the pressure control valve, and the flow rate of the hydraulic medium to the hydraulic servo of the input side disk is controlled by changing the output voltage Vin to the flow rate control valve. Controls the speed ratio of the gear transmission. Here, when considering the flow rate Q of the hydraulic medium from the flow control valve to the hydraulic servo of the input side disk when changing the speed, that is, when changing the speed ratio of the belt type continuously variable transmission, Q is expressed as follows: (However, in the case of inflow to the servo part).

Q oc ■il J■messs-a (1) where Vin: Output voltage ΔPl to the flow control valve: Pressure difference between the pressure control valve side and the hydraulic servo side of the input side disk in the flow control valve/i? Since the line pressure is sent from the pressure control valve to the L% control valve, from equation (1), Q is ΔPl, that is, the line pressure P1! It can be seen that it is influenced by A change in Q causes a change in the gear speed (the amount of change in the speed ratio of the continuously variable transmission per unit time), and therefore the degree of torque Nin of the input side rotation of the continuously variable transmission. In a transmission, the relationship shown in Figure 1 occurs.

On the other hand, if Q increases rapidly, the adjustment range of the pressure control valve is exceeded and the line pressure Pl becomes lower than the target value. FIG. 2 shows the change in line pressure Pl when Q increases rapidly. However, ΔNin: =N'in -N1nN' + n
: Target input rotational speed of the continuously variable transmission Nin : Actual input rotational speed of the continuously variable transmission ΔPl: Decrease from the target line pressure, that is, as shown in FIG. 3(b), Q is only Vin, Pl should be defined only by Vout, but as shown in Figure 3(a), Q is defined by Vout.
Therefore, Pl receives interference from Vin, and control accuracy deteriorates.

An object of the present invention is to appropriately control line pressure and flow rate by avoiding deterioration in control accuracy caused by mutual interference between the line pressure of the line pressure generation valve and the flow rate from the flow rate control valve to the hydraulic servo. An object of the present invention is to provide a hydraulic control device for a belt type continuously variable transmission that can perform the following steps.

To achieve this objective, according to the invention, the output voltage Vin to the flow 1 control valve is changed to the output voltage Vout to the pressure control valve.
The output voltage Vout to the pressure control valve is corrected in relation to the output voltage Vin to the flow control valve.

The present invention will be described in detail with reference to FIG. 4 and subsequent figures.

FIG. 4 shows a constant fuel consumption rate line (solid line) and a constant horsepower line (broken line) on the engine rotation speed versus engine output torque. The unit of the equal horsepower line is PS, and the unit of the equal fuel consumption rate line is g/
P S -h. The dash-dotted line is the characteristic when the throttle valve is fully open, and is the operating limit of the engine. Line A is a line connecting the points that give the minimum fuel efficiency for each output horsepower, and in conventional transmissions, the gear ratio was set like line B, resulting in poor fuel efficiency. In the power transmission device of the embodiment, the required horsepower of the engine is set as a function of the amount of operation of the accelerator pedal, that is, the amount of depression, so that the engine rotational speed and engine output torque are specified by line A at each required horsepower. An internal combustion engine is operated. The engine rotation speed is continuously variable transmission.
transmission: Hereinafter referred to as CVT. ), and the engine output torque is controlled by changing the intake system throttle opening. The function is determined on the assumption that the required horsepower increases as the amount of depression of the accelerator pedal increases.

Various mechanisms have been conventionally proposed for CVT, but in FIG. 5, a belt-driven type will be described which has a large transmittable torque and is compact.

In FIG. 5, an output shaft 2 of an internal combustion engine 1 is connected to an input shaft 5 of a CVT 4 via a clutch 3. Input shaft 5
and output shafts 6 are provided parallel to each other, an input side fixed disk 7 is fixed to the input shaft 5, and an input side movable disk 8 is movable in the axial direction by a spline or a pole bearing on the outer periphery of the input shaft 5. When fitted, the output side fixed disk 9 is fixed to the output shaft 6, and the output side movable disk 1
0 is fitted to the outer periphery of the output shaft 6 via a spline or a Maball bearing so as to be movable in the axial direction. The pressure-receiving area of the movable disk is set so that the input side is larger than the output side, and the axial positions of the fixed disk and the movable disk are opposite to each other on the input side and the output side. Fixed disc 7.9 and movable disc 8, 10
The opposing surfaces of the belt 11 are tapered so that the distance between them increases toward the outside in the radial direction, and the belt 11 has a truncated conical cross section.
is applied between the input and output disks. Therefore, when tightening the fixed and T-moving disks, the radial contact position of the belt 110 on the disk surface changes continuously as the force changes.The contact position of the belt 11 on the surface of the input side disk 7.8 changes continuously. Moving radially outward, the belt 1 on the output side disk 9, 100 surface
When the first contact position is radially inward, the power of the force detection shaft 6 is transmitted to a drive shaft (not shown). The torque sensor 15 detects the torque of the input shaft 5, and therefore the output torque Te of the internal combustion engine 1, from changes in torsional stress or torsional angle in the input shaft 5. The accelerator pedal sensor 16 detects whether the accelerator pedal 18 is depressed by the driver's foot 17.

The opening degree of the intake throttle of the internal combustion engine l is controlled by an electromagnetic throttle actuator 19. The input side and output side rotation angle sensors 20 and 21 are each mounted on a disk 7.1.
The rotation angle of 0, and therefore the rotation speed, is detected. The line pressure generation valve 24 adjusts the line pressure Pg of the oil passage 29 by controlling the amount of oil as a hydraulic medium sent from the reservoir 26 via the oil passage 27 by the oil pump 25 to the oil passage 28. do. The hydraulic servo of the output side movable disk IO is supplied with line pressure Pl via an oil passage 29. The flow rate control valve 30 controls the amount of Ω oil flowing into and out of the input movable disk 8 . In order to maintain the speed ratio e of the CVT 4 constant, the oil passage 33 is disconnected from the line pressure oil passage 31 and the drain oil passage 32 branching from the oil passage 29, that is, the axial direction of the input side movable disk 8 is cut off. In order to maintain the position constant and increase the speed ratio e, the oil passages 31 to 3 are
3, the tightening force between the input side disks 7 and 8 increases, and in order to decrease the speed ratio e, the hydraulic pressure of the hydraulic servo of the movable disk 8 is transferred to the atmosphere side via the drain oil path 32. The thrust between the input disks 7 and 8 is reduced. Although the oil pressure in the oil passage 33 is below the line pressure Pl, the working area of the piston of the hydraulic servo on the input side movable disk 8 is larger than the working area of the piston of the hydraulic servo on the output side movable disk 10. The force for tightening the disks 7.8 can be greater than the force for tightening the output side disks 9, 1o. The electronic control unit 38 has D/A (
digital/analog) converter 40, input interface 41, A/D (analog/digital) converter 42, C
It includes PU43, RAM44, and ROM45. The analog outputs of the torque sensor 15 and the accelerator pedal sensor 16 are sent to the A/D converter 42, and the rotation angle sensor 20
, 21 are sent to the input interface 41.

Outputs to the electromagnetic actuator 19, flow control valve 30, and line pressure generation valve 24 are sent from the D/A converter 40 via amplifiers 49, 50, and 51, respectively.

FIG. 6 shows an amplifier 490 for the throttle actuator 19.
It shows the relationship between input voltage and output current. FIG. 7 shows the relationship between the throttle actuator 190 input current and the intake system throttle opening. Therefore amplifier 49
The throttle opening increases in proportion to the input voltage. FIG. 8 shows the relationship between the input voltage and output current of the amplifier 50 for the flow control valve 30, and FIG. 9 shows the relationship between the input voltage of the flow control valve 30 and the flow rate to the input side hydraulic servo of the CVT 4. ing. Therefore, the speed ratio e is proportional to the change in the amplifier 500 Å voltage. Figure 1O shows the relationship between the input voltage and output current of the amplifier 51 for the line pressure generating valve 24,
The figure shows the input current of the line pressure generating valve 24 and the line pressure P7! Which relationship does it show? Therefore, the line pressure Pg changes linearly with changes in the input voltage of the amplifier 51. Even if the input current of the line pressure generation valve 24 is O, the line pressure P
Since l is maintained at pel (PNl''r O), even if a disconnection occurs or a failure occurs in the electronic control unit 38, the movable disk 8
．． A predetermined hydraulic pressure is supplied to the hydraulic servo No. 10, and the minimum torque transmission in the CVT 4 is ensured.

FIG. 12 is a block diagram of an embodiment of the present invention.

Before explaining this block diagram, the technical idea of the present invention will be explained.

From equation (1), the following equation holds true.

Q=to@vln・f(Vout)-1...11(2)
However, the specific form of K is a constant f (Vout), which is determined by the mechanical and frictional relations of the CVT, and cannot be defined strictly, but in relation to Q, Vout is in the form of a product ( 2) It is considered that it enters the equation. Furthermore, m is defined from the following equation.

m = Pl/Pml++++s++msam (3
)U Vout/ Vmout ・1・−・・・ (
4) Pme: Standard line pressure Vmou as reference value
t: When the output voltage m to the line pressure generating valve that generates the standard line pressure Pml is introduced into equation (2), the following is obtained.

Q=to -Vin/m=to *Valy, ``(5) Therefore, by setting Va as new Vin and defining Vin by the following equation, the influence of line pressure Pl on flow @Q can be canceled. , Vin = 1 (Nin-Nin) 7m ease (5
Furthermore, in the line pressure generating valve, the output flow rate to the flow rate control valve is Q, the input flow rate from the pump is defined as QP, and the return flow rate to the oil reservoir is defined as Qr. Then, the following (
holds true.

Qr=QP-Q ・・・−・・・・・・−・(
7) FIG. 13 shows the relationship between Qr and line pressure Pl.

When Qr decreases, that is, when Q increases, line pressure Pl decreases from the set value. In equation (7), Q−cV i
n, so if Vout is linearly corrected by Vin, Vout = K2sTe@Nin/Nout+3@
By defining Vin'' (8) where Te: 2 for the output torque of the engine and K3: constant Vout according to equation (8), the influence of the flow rate Q on the line pressure Pl can be canceled.

The block diagram in FIG. 12 will be explained.

At block 55, the accelerator pedal depression amount Xacc is converted into a required horsepower ps'. The required horsepower ps' is the pedal stroke @,
It is set as a function of Xacc that increases as acc increases. In block 56, the required horsepower ps'
is the engine, that is, the input shaft 5 [゛1 standard rotational speed N'i
Converted to n. Required horsepower PS' and [ ] Target rotational speed N'
The relationship with in is shown by line A in FIG. In other words, the engine rotational speed at which the required horsepower ps' can be obtained at the minimum fuel consumption rate is 1'' target rotational speed. 57, the deviation N'in between the target rotational speed Nin and the actual rotational speed Nin
-Nin is required. In the feedback gain of block 58, Vin is calculated from equation (6). Thereby, Q that can produce the target manual rotational speed N'in is ensured regardless of the inlet pressure Pg. In block 61, Vout is calculated according to equation (8). As a result, there is no problem in torque transmission in CVT 4 and minimum (
This is maintained regardless of the line pressure pefJ''-Q (which can suppress power loss).

In addition, in Fig. 12, Vin and Vout are as shown in flow 11 (
Control valve amplifier 50 and line pressure generation valve amplifier 51
Since the actual output voltages Vin, Vout to the flow control valve 30 and the line pressure generation valve 24 are amplified at
It is a constant multiple of . Therefore, the gains of these amplifiers 50 and 51 are expressed as Kl in equations (6) and (8) by 2. The value multiplied by 3 is Kl, and 2. If we define 3 as (6i
, (s) Expression Vin and Vout as flow control valve 3
0 and the actual output voltage to the line pressure generating valve 24.

FIG. 14 is a flowchart of a program according to the block diagram of FIG. 12. In step 66, the amount of depression Xa of the accelerator pedal 18 is determined from the input from the accelerator pedal sensor 16.
cc detected and target output horsepower PS corresponding to X ace
′ is calculated. In step 67, the target horsepower ps' is changed to the target input rotational speed N1n (the target rotational speed N'e of one engine 1).
) is calculated. In step 68, Vout is standardized, that is, m-Vout/Vmout is calculated. In step 69, Vin is calculated from equation (6). Step 7
At 0, the output torque Te of the engine.

Read the output rotation speed Nout of CVT 4. In step 71, Vout is calculated from equation (8).

As described above, according to the present invention, the flow 1 of the flow rate control valve and the line pressure of the line pressure generation valve are prevented from interfering with each other and deviating from the target value, thereby improving the control accuracy of the continuously variable transmission. can be done.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between line pressure and shift speed, etc. in a conventional device, and Fig. 2 is a diagram showing temporal changes in line pressure PI, etc. when the flow rate Q of the flow rate control valve increases rapidly in the conventional device. , Fig. 3 is a diagram showing the mutual interference between the flow control valve and the line pressure generation valve, Fig. 4 is a diagram showing the equal horsepower line and the equal fuel consumption rate line on the engine rotational speed-output torque coordinate system, and Fig. 5 Figure 6 is a diagram showing the configuration of a vehicle power transmission device to which the present invention is applied, Figure 6 is a diagram showing the input/output characteristics of the amplifier for the throttle actuator, and Figure 7 is a diagram showing the relationship between the input of the throttle actuator and the throttle opening. 8 is a diagram showing the input/output characteristics of the amplifier for the flow control valve, and FIG. 9 is a diagram showing the relationship between the input of the flow control valve and the speed ratio of the CVT.
Fig. 10 is a diagram showing the input/output characteristics of the amplifier for the line pressure generating valve, Fig. 11 is a diagram showing the relationship between the input of the line pressure generating valve and the line pressure, and Fig. 12 is a block diagram of the embodiment of the present invention. Figure 13 is a graph showing the relationship between the line pressure Pl in the line pressure generation valve and the return 'il Qr.
The figure is a flowchart of a program according to the block diagram of FIG. 1... Engine, 4 ・CVT, 7.8.9, 10
= Disk, 24... Line pressure generation valve, 30...
- Flow rate control valve, 38... electronic control device. Patent applicant Toyota Motor Corporation Figure 1 Figure 2 Time Figure 3 (a) (b,) Figure 6 Input voltage of amplifier 49 0 Input voltage of amplifier 51 Figure 13 Set value line pressure Pt

Claims (1)

[Claims] 1. A belt type continuously variable transmission comprising: a pair of inner disks;
It is equipped with a pair of output-side disks, and a belt that is hung between the input-side disk and the output-side disk to transmit power, and a pressure control valve controls the release amount of the hydraulic medium supplied from the hydraulic pump. The flow rate control valve controls the IF force supplied as line pressure to the hydraulic servo of the disk, and controls the flow rate of hydraulic medium with a pressure higher than the minimum line pressure and the hydraulic pressure from the hydraulic servo of the input side disk to the hydraulic servo of the input side disk. Controls the discharge flow rate of the medium to a pressure below the maximum line pressure, controls the line pressure by changing the output voltage Vout to the pressure control valve in relation to the transmission torque of the continuously variable transmission, and controls the line pressure to the flow rate control valve. In a hydraulic control device for a belt-type continuously variable transmission that controls the speed ratio of the continuously variable transmission by controlling the flow rate of hydraulic medium to the hydraulic servo of the input side disk by changing the output voltage V in, flow control is performed. The output voltage V in to the valve is corrected in relation to the output voltage Vout to the pressure control valve, and the output voltage Vout to the pressure control valve is /
A hydraulic control device for a belt type continuously variable transmission, characterized in that correction is performed in relation to an output voltage Vin to an N quantity control valve. 2. Vmout: Output voltage to the pressure control valve that produces standard line pressure as a reference value, m': = Vout/Vmout. Nin: Target input side rotational speed of the continuously variable transmission, Nin:
Actual input side rotation speed of the continuously variable transmission, Te: engine output torque, Kl, 2, 3: constants, Vin=Kl (Nin-Nin)/(NinIIm)
)Vout = K2 ・Te ・(1+Nin/No
The hydraulic control device for a belt-type continuously variable transmission according to claim 1, characterized in that: