JPS5926656A - Stepless transmission type power transmitting apparatus for use in vehicle - Google Patents

Abstract

PURPOSE:To control a value to be controlled to a desired value smoothly and promtly, by setting a reference value separately from the desired value, and executing feedback control of the value to be controlled considering the reference value as a desired value. CONSTITUTION:At a block 55, a desired revolutional speed Nin* on the input side is calculated on the basis of a throttle opening thetath. At a summing point 56, the deviation (Nin*-Nin) between the desired revolutional speed Nin* and the actual revolutional speed Nin on the input side detected by a CVT4 is calculated. At a block 57, a reference revolutional engine speed - Nin is calculated on the basis of the deviation (Nin*-Nin). At a summing point 58, the deviation (-Nin-Nin) is calculated and it is furnished to a flow control valve 30 via a feedback gain 59 and an amplifier 50 for the flow control valve. Resultantly, the flow rate Q from the flow control valve 30 to a servomotor on the input side of the CTV4 is changed and the speed ratio of the CVT4 and hence the actual revolutional speed Nin is changed. That is, the actual revolutional speed Nin is feedback controlled by considering the reference value - Nin as a desired value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuously variable vehicular power transmission system equipped with a continuously variable transmission capable of continuously changing a speed ratio.

The applicant has proposed a continuously variable transmission (hereinafter referred to as "CvT") that can control the speed ratio (2) so that the fuel efficiency is minimized relative to the horsepower required by the driver.
Patent Application No. 57-40747 and Patent Application No. 57-6
No. 7362. In such a vehicle power transmission system, the engine rotation speed (
= input side rotational speed of CVT), but the present applicant is aiming to smoothly and quickly shift the engine rotational speed to the target value during a transient state in such a continuously variable transmission vehicle power transmission system. In order to avoid this, the CVT's shifting speed (
A device for correcting the amount of change in CVT speed ratio e per unit time was disclosed in Japanese Patent Application No. 57-71466.

However, with this device, although it is possible to compensate for changes in shift speed related to line pressure as shown in Figure 1,
As shown by the solid line in the diagram, it is not possible to effectively compensate for the phenomenon in which the speed change speed (time change in engine speed) decreases as it approaches the target value. The phenomenon in which the shift speed decreases as it approaches the target value is the CVT speed.
) The flow rate Q of the hydraulic medium sent to the input side hydraulic servo of the CVT (3) is expressed by the following equation, and Q - =
In below, I: Control current of flow control valve (input terminal) ΔP: This occurs because the differential pressure ΔP between the outlet and inlet of the flow control valve changes depending on the shift position.

Therefore, in order to obtain a desired speed change speed by controlling Q by adjusting I by adjusting the feedback gain, it is necessary to detect the differential pressure ΔP, but a special sensor is required to detect the differential pressure ΔP.

An object of the present invention is to provide a continuously variable power transmission system for a vehicle that can smoothly and quickly shift a controlled variable to a target value without using a special sensor.

In order to achieve this purpose, in the continuously variable transmission vehicle power transmission system of the present invention, a comparison value is set separately from the original target value of the controlled variable, and the controlled variable is fed back using the comparison value as the target value. control to shift the controlled quantity to its original target value.

(4) Further, according to the present invention, the target engine rotation speed is set as a function of the amount of depression of the accelerator pedal, and the engine rotation speed is controlled via speed ratio control of the continuously variable transmission. In the power transmission device, a comparison rotation speed is set separately from the target engine rotation speed based on the target rotation speed, and the engine rotation speed is feedback-controlled using the comparison rotation speed as the target value.

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

In FIG. 3, 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, the input side fixed disk 7 is fixed to the input shaft 5, and the input side movable disk 8 is movable in the axial direction by splines or ball bearings etc. 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 rotating disk 0 is fitted with a spline or a ball bearing etc. on the outer periphery of the output shaft 6 so as to be movable in the axial direction. . The pressure-receiving surface (5) of the movable disk is set so that input side>output side, and the axial positions of the fixed disk and the movable disk are opposite to each other on the input side and output side. Fixed disc 7.9
The opposing surfaces of the movable disks 8 and 10 are tapered so that the distance between them increases radially outward, and a belt 11 having a truncated conical cross section is disposed between the disks on the input side and the output side. Therefore, when the fixed and movable disks are tightened, the radial contact position of the belt 1 on the disk surface changes continuously as the force changes. When the contact position of the belt 11 on the surface of the input disk 7.8 moves radially outward, the output disk 9,1o
The contact position of the bell) 11 on the surface moves inward in the radial direction, and the speed ratio e of the CVT 4 (-÷ tatami matsufuku to sleet) increases, and in the opposite case, e decreases. do. Output shaft 6
The power is transmitted to drive wheels (not shown).

Throttle opening sensor 18id Intake system throttle opening θ
Detect th. The acceleration pedal and the intake system throttle valve are connected so that the output horsepower of the engine is a desired function of the amount of depression of the accelerator pedal. Input side
The output rotation angle sensors 20, 2] respectively detect the rotation angle and therefore the rotation speed of the disk 7.10. The pressure regulating valve 24 adjusts the line pressure Pl 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 . The hydraulic servo of the output side movable disk 10 is supplied with line pressure Pl via two oil passages. The flow rate control valve 30 controls the amount of 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 that branch from the oil passage 29,
That is, in order to maintain the axial position of the input side movable disk 8 constant and increase the speed ratio e, oil is supplied to the oil passages 31 to 33, and the tightening force between the input side disks 7 and 8 is increased. In order to increase the speed ratio e and decrease the speed ratio e, the hydraulic pressure of the hydraulic servo of the movable disk 8 is conducted to the atmosphere through the drain oil passage 32 to reduce the thrust (7) between the input side disks 7.8. Although the oil pressure in the oil passage 33 is below the line pressure Pl, the piston action area of the hydraulic servo on the input side movable disk 8 is larger than the piston action area of the hydraulic servo on the output side movable disk 10.
．． It is possible to make the force for tightening the output side discs 8 and 8 larger than the force for tightening the output side disks 9 and 10. Output side disk 9,1
0, the line pressure Pl is controlled by the pressure regulating valve 24 so that force is generated to tighten the belt 1 to ensure torque transmission without slipping, and the tightening of the input side disc 7.8 controls the force by controlling the flow rate. The speed ratio is controlled by changing the valve 30.

The electronic control unit 38 includes D/A (digital/analog converters) connected to each other by an address data bus 39.
401 person interface 41, A/D (analog/
Digital converter) 42, CPU43, RA, M44, R
Contains OM45. The analog output of the throttle opening sensor 18 is sent to the A/D 42, and the rotation angle sensor 2
The pulses 0, 21 are sent to the input interface 41. The output to the flow rate control valve 3o and the pressure regulating valve 24 is D/A.
40 through amplifiers ゛(8) 50, 5], respectively.

The basic idea of the present invention will be explained with reference to FIGS. 4 and 5. In Fig. 4, the horizontal axis is the intake system throttle opening θt
h, the vertical axis is the target input side rotational speed Nin*(
- target engine rotational speed Ne*). Said patent application 1987-
As described in detail in No. 67362, etc., the θth - Nin* relationship is set so that the required horsepower can be obtained at the minimum fuel efficiency. FIG. 5 shows changes over time in the input side rotational speed Nin of the CVT 4, etc. At time t1, the target input side rotational speed Nin* changes significantly to Nin*1 in a stepwise manner. In the conventional device, Nin is feedback-controlled using Nin* as the direct target value, and as described above in Fig. 2, Nin
When in-' approaches the target value, there is a problem that the time change decreases and the arrival of the target value is delayed. In the present invention, in addition to the target input side rotation speed N in*, the comparison rotation speed N 1n
is set, and N i n is feedback-controlled with N i n set as a target value. Nin ld Nin is set as the locus of Nin until it reaches the original target value Nin*, and the optimum one is set based on experiments or theoretical formulas (9) and in consideration of various control performances. The control of the controlled variable via the comparison value is based on the input side rotation speed N.
In addition to the control of i n, other things such as CVT 4
The speed ratio e1 can also be applied to the control of the throttle opening θth in the above-mentioned Japanese Patent Application No. 57-40747.

FIG. 6 is a block diagram of an embodiment of the present invention. Throttle opening θ detected by throttle opening sensor 18
Based on th, block 55 determines the target input side rotation speed N.
1n* is calculated as a function of θth. Addition point 56
Then, N1n* and the actual input side rotation speed Ni of CVT 4
Take the deviation Nin*-Njn from n. In block 57, a comparison rotational speed Nin is calculated based on Nin*-Nin. At the summing point 58, the deviation Nin -Nin is taken, and Nin -Nin is sent to the flow control valve 30 via the feedback gain 59 and the flow control valve amplifier 5o. As a result, the flow rate Q from the flow control valve 30 to the input side servo of the CVT 4 changes, and the speed ratio e of the CVT 4 changes.
, therefore Nin changes. That is, N in is feedback-controlled using the comparison rotational speed Min(10) as a target value. In block 60, the output torque Te at the 41st point is expressed as the throttle opening θt.
It is calculated as a function of h and input side rotational speed Nin.

In block 61, Vout is calculated as a function g (Te, Nin, Nout) of Te, Nin, and Nout.

Vout is sent to the pressure regulating valve 24 via the pressure regulating valve amplifier 51. As a result, the line pressure Pl is maintained at a substantially minimum pressure that does not impede torque transmission by the belt 11, and power loss and reduction in belt durability due to excessive line pressure are prevented.

FIG. 7 is a flowchart of the algorithm of the present invention. In step 68, the throttle opening degree θth is read. In step 69, a target value Nin* of the input side rotational speed Nin of the CVT 4 is calculated as a function of the throttle opening degree θth. In step 70, engine output torque Te and cooling water temperature Tw are read as operating data. In step 7], change width ΔMin of comparison rotational speed Min is expressed as θth, T
It is calculated as a function f(θth, Te, Tw) of e and Tw. In step 72, it is determined whether the speed ratio e of the CVT 4 is the minimum value emin (in the range of e<maximum value emax (I)), and if it is correct, the process proceeds to step 76.
If it is different, proceed to step 77. In step 76, it is determined whether the input side rotational speed N in is greater than Nin*, and if Nin ) Nin *, proceed to step 78, and if Nin <: Nin'', step 78 is skipped. In step 77, O is substituted for ΔNin. In step 78, one ΔNin is set to ΔNin.
Assign to . In step 79, Nin+ΔNin is
Assign to n. Therefore, if N1n is larger than the target value Nin*, the comparison rotational speed Nin increases by the change ΔNin calculated in step 7], and Nin becomes the target value Ni.
If it is less than or equal to n*, the comparison rotational speed Min decreases by the change amount ΔNin calculated in step 71. Furthermore, e*<e
If mln or e″′>emaX, ΔNin td is set to 0 in step 77, and Nin is not changed in step 79. In such a case, even if Nin is changed, CVT 4 cannot follow the change in Nin. In step 80, the deviation ΔNi between Nin and Nin
Calculate n. In step 81, the flow control valve amplifier 5
The voltage V i n sent to 0 is Vin:=K・ΔN i n
Calculate from (]2). However, K is a constant. As a result, Vin is feedback-controlled using the comparison rotational speed Vin as a target value. In step 82, the time count Δt is reset. The time count ΔL counts the passage of time based on the input of clock pulses.

In step 83, it is determined whether Δt>feedback interval Δtl, and if Δt>Δt1, step 68
If Δt<Δt1, the process proceeds to step 84. At step 84, Δt is counted, and the process returns to step 83. In this way, when the comparison rotational speed Min is newly set in step 79, Nin is set at a constant feedback interval Δt
1 is feedback controlled to Min, and the time is Δt1
When the time has elapsed, a new comparative rotational speed Min is set again in step 79.

Therefore, the comparison rotational speed Min is Nin <Nin*
In the case of , it becomes as shown in Figure 8(a), and Nin ) N
In the case of in*, force as shown in Fig. 8(b). In this way, N in quickly transitions to Nin*.

Even in a steady state where the time change of Nin is almost constant, Ni
By setting an appropriate Min for n and performing feedback control using it as the target value (13), steady-state deviations due to oil leakage, etc. can be removed.

As described above, according to the present invention, since the controlled variable is feedback-controlled using a comparison value set separately from the target value as the target value, the controlled variable can be appropriately guided to the target value, and the tracking performance and Responsiveness can be improved. Furthermore, steady state deviations during steady state can be removed.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between line pressure, CVT oil temperature, and gear shift speed. Figure 2 is a graph showing the change in engine rotation speed over time when the target value of engine rotation speed changes in a stepwise manner. 3 is a configuration diagram of an embodiment of the present invention, FIG. 4 is a graph showing the relationship between intake system throttle opening and target input side rotation speed, and FIG. 5 is a graph showing the target input rotation speed, comparative rotation speed,
and a graph showing the time change of the actual input side rotation speed,
FIG. 6 is a block diagram of an embodiment of the present invention, FIG. 7 is a flowchart 1 of the algorithm of the present invention, and FIG. 8 is a diagram showing time variation (14) of the comparison rotational speed. 1. Engine body, 4. CVT, 18. Throttle sensor, 30 Flow control valve, 38. Electronic control device. Patent applicant: Toyota Motor Corporation Figure 1 Figure 2 Time Figure 4 Intake system throttle opening θth

Claims (1)

[Claims] 1. In a continuously variable vehicle power transmission system equipped with a continuously variable transmission capable of continuously changing the speed ratio, a comparison value is set separately from the original target value of the controlled variable. A control device for a continuously variable transmission power transmission system for a continuously variable vehicle, characterized in that the control amount is feedback-controlled using the comparison value as a target value to shift the controlled amount to the original target value. 2. In a continuously variable vehicle power transmission system in which a target engine rotational speed is set as a function of the amount of depression of an accelerator pedal, and the engine rotational speed is controlled via speed ratio control of a continuously variable transmission, when the engine rotational speed reaches the target rotational speed. A continuously variable transmission power transmission device for a vehicle, characterized in that a comparison rotation speed is set separately from a target engine rotation speed based on the target engine rotation speed, and the engine rotation speed is feedback-controlled using the comparison rotation speed as a target value. (1) 3. The continuously variable transmission according to claim 2, wherein the comparative rotational speed is set as a function of at least one of an intake system throttle opening, an engine output torque, and an engine temperature. Power transmission device for type vehicles. 4. The variation range i n of the comparison rotation speed Win is set as a function of at least one of the intake system throttle opening θth, the engine output torque Te, and the engine cooling water temperature TW, and the target engine rotation speed Ne* and the actual rotation are Compare the speed Nin, and if Nin<Nin*, Min+ΔMin
Assign to Nin, and if Nin)Nin*, then Min
4. The continuously variable transmission power transmission system for a vehicle according to claim 3, wherein -ΔMin is substituted for damping 1n.