JPH06100267B2 - Power transmission device for continuously variable vehicle - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a continuously variable vehicle power transmission device including a continuously variable transmission whose speed ratio can be continuously changed.

[Prior art]

The applicant of the present invention has proposed a continuously variable transmission (hereinafter referred to as "CVT") capable of controlling the speed ratio so as to minimize the fuel consumption rate with respect to the horsepower required by the driver. −40747
And Japanese Patent Application No. 57-67362. In such a power transmission device for a vehicle, the engine speed (= the input side speed of the CVT) is feedback-controlled through the CVT speed ratio control. In a power transmission device for an electric vehicle, a device for correcting a CVT shift speed (amount of change in CVT speed ratio e per unit time) in order to smoothly and promptly shift an engine rotation speed to a target value during a transition, It was disclosed in Japanese Patent Application No. 57-71466.

[Problems to be Solved by the Invention]

However, this device can compensate for the change in the shift speed related to the line pressure as shown in FIG. 1, but as shown by the solid line in FIG. 2, the shift speed (= change in engine speed with time). It cannot be effectively compensated for the phenomenon that decreases as the target approaches the target value. The phenomenon that the shift speed decreases as it approaches the target value is that the CVT input hydraulic servo is changed to change the CVT gear ratio e (= CVT output speed Nout / CVT input speed Nin). The flow rate Q of the hydraulic medium to be sent is represented by the following equation, However, i: Control current (input current) of the flow rate control valve ΔP: This occurs because the pressure difference ΔP between the outlet and the inlet of the flow rate control valve changes depending on the shift position. Therefore, the differential pressure ΔP must be detected in order to control Q by i by adjusting the feedback gain to obtain a desired shift speed, but a special sensor is required for detecting the differential pressure ΔP. . An object of the present invention is to provide a continuously variable transmission power transmission device for a vehicle capable of smoothly and promptly shifting a controlled variable to a target value without using a special sensor.

[Means for Solving the Problems]

According to the present invention, the target engine rotation speed is set as a function of the depression amount of the accelerator pedal, and the actual engine rotation speed is controlled via the speed ratio control of the continuously variable transmission so as to match the target engine rotation speed. In a continuously variable transmission power transmission device for a vehicle, based on the target engine rotation speed, apart from the target engine rotation speed, the actual engine rotation speed changes linearly with the passage of time toward the target engine rotation speed. A means for setting a comparative rotation speed for changing the engine rotation speed to a desired value, and a means for feedback-controlling the engine rotation speed with the comparison rotation speed as an immediate target value to linearly bring the engine rotation speed closer to the target engine rotation speed. As a result, the above-mentioned problems have been achieved.

[Action]

In the present invention, the comparison rotation speed is set separately from the target engine rotation speed, and the engine rotation speed is feedback-controlled with the comparison rotation speed as the immediate target value. In this case, the comparative rotation speed is determined depending on the target engine rotation speed, and is set so that the engine rotation speed can change linearly. As a result, as shown in FIG. 2, for example, even when the target engine speed changes stepwise, the continuously variable transmission can be controlled so as to raise the engine speed linearly. Therefore, smoother acceleration performance can be obtained.

【Example】

Embodiments of the present invention will be described with reference to the drawings. In FIG. 3, the output shaft 2 of the internal combustion engine 1 is connected to the input shaft 5 of the CVT 4 via the clutch 3. The input shaft 5 and the output shaft 6 are provided in parallel with each other, the input side fixed disk 7 is fixed to the input shaft 5, and the input side movable disk 8 is provided.
Is movable in the axial direction, is fitted to the outer periphery of the input shaft 5 by a spline or a ball bearing, the output side fixed disk 9 is fixed to the output shaft 6, and the output side movable disk 10 is movable in the axial direction. The outer circumference of the output shaft 6 is fitted with a spline, a ball bearing, or the like. The pressure receiving area of the movable side disk is set so that the input side> the output side, and the arrangement of the fixed disk and the movable disk in the axial direction is opposite to each other on the input shaft and the output side. The opposed surfaces of the fixed disks 7 and 9 and the movable disks 8 and 10 are formed in a tapered surface shape that increases their distances outward in the radial direction, and the belt 11 having a truncated cone-shaped cross section is provided on the input side and the output side. Can be hung between discs. Therefore, the radial contact position of the belt 11 on the disk surface continuously changes as the fastening force of the fixed and movable disks changes. When the contact position of the belt 11 on the surface of the input side disks 7 and 8 moves radially outward, the output side disks 9 and 10
The contact position of the belt 11 on the surface of is moved inward in the radial direction, the speed ratio e of the CVT 4 (= rotation speed Nout of the output shaft 6 / rotation speed Nin of the input shaft 5) increases, and vice versa. e decreases. The power of the output shaft 6 is transmitted to drive wheels (not shown). The throttle opening sensor 18 detects the intake system throttle opening θth.
To detect. The accelerator pedal and the intake system throttle valve are connected so that the output horsepower of the engine becomes a desired function of the depression amount of the accelerator pedal. Input side and output side rotation angle sensor 20,
Reference numeral 21 detects the rotation angles of the disks 7 and 10, respectively, and thus the number of rotations. The pressure regulating valve 24 adjusts the line pressure Pl of the oil passage 29 by controlling the escape amount of the oil as a hydraulic medium sent from the reservoir 26 via the oil passage 27 to the oil passage 28 by the oil pump 25. To do. The hydraulic servo of the output side movable disk 10 is supplied with the line pressure Pl via the oil passage 29. The flow rate control valve 30 controls the inflow / outflow amount of oil to / from the input side movable disk 8. In order to keep the speed ratio e of the CVT 4 constant, the connection between the oil passage 33 and the line pressure oil passage 31 branched from the oil passage 29 and the drain oil passage 32 is cut off, that is, the axis line of the input side movable disk 8 is cut off. In order to maintain the position in the direction constant and increase the speed ratio e, oil is supplied from the oil passages 31 to 33 to increase the tightening force between the input side disks 7 and 8 and decrease the speed ratio e. In order to achieve this, the hydraulic pressure of the hydraulic servo of the movable disk 8 is conducted to the atmosphere side via the drain oil passage 32, and the input side disk 7,
Reduce thrust between eight. The hydraulic pressure in the oil passage 33 is equal to or lower than the line pressure Pl, but the piston working area of the hydraulic servo of the input side movable disk 8 is larger than the working area of the piston of the hydraulic servo of the output side movable disk 10, so that the input side disks 7, 8 are It is possible to make the tightening force on the output side disks 9 and 10 larger than the tightening force. The line pressure Pl is controlled by the pressure regulating valve 24 so that a tightening force that secures the torque transmission is generated in the output side disks 9 and 10 without the belt 11 slipping, and the tightening force of the input side disks 7 and 8 is flowed. The speed ratio is controlled by changing the control valve 30. The electronic control unit 38 has a D / A (digital / analog converter) 40 connected to each other by an address data bus 39,
It includes an input interface 41, an A / D (analog / digital converter) 42, a CPU 43, a RAM 44, and a ROM 45. The analog output of the throttle opening sensor 18 is sent to the A / D 42, and the pulses of the rotation angle sensors 20, 21 are sent to the input interface 41. Outputs to the flow control valve 30 and the pressure regulating valve 24 are sent from the D / A 40 via amplifiers 50 and 51, respectively. The basic idea of the present invention will be described with reference to FIGS. 4 and 5. In FIG. 4, the horizontal axis indicates the throttle opening θ of the intake system.
th, the vertical axis is the target input side rotation speed Nin ^* (= target engine rotation speed Ne ^* ) of CVT4. As described in detail in Japanese Patent Application No. 57-67362, etc., the θth-Nin ^* relationship is set so that the required horsepower can be obtained at the minimum fuel consumption rate. FIG. 5 shows changes with time of the input side rotation speed Nin of the CVT 4 and the like. At time t1, the target input side rotation speed Nin ^* changes greatly to Nin ^* 1 in steps. In the conventional device, Nin is feedback-controlled with Nin ^* as a direct target value. As described above with reference to FIG. 2, when Nin retards to the target value, the time change decreases and the arrival at the target value is delayed. There was an evil. In the present invention, the comparative rotation speed in is set separately from the target input side rotation speed Nin ^*, and Nin is feedback-controlled with in as a target value. Nin is the original target value Nin ^*
Is set as the locus of Nin until reaching, and the optimum one is set in consideration of various control performances based on experiments or theoretical formulas. Control of the controlled variable via the comparison value is not limited to control of the input side rotation speed Nin,
For example, it can be applied to control of the speed ratio e of CVT4 and the throttle opening θth in 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, in block 55, the target input side rotation speed Ni
Calculate n ^* as a function of θth. At addition point 56, N
Deviation between in ^* and actual CVT4 input speed Nin ^* -
Take Nin. At block 57, based on Nin ^* -Nin,
The comparative rotation speed in is calculated. At the summing point 58, the deviation
in−Nin is taken, in−Nin is the feedback gain
59 and the flow control valve amplifier 50 to the flow control valve 30. As a result, the flow rate Q from the flow rate control valve 30 to the input side servo of the CVT 4 changes, and the speed ratio e of the CVT 4, and thus Nin changes. That is, Nin is feedback-controlled with the comparative rotation speed in as the target value. In block 60, the output torque Te of the engine is calculated as a function of the throttle opening θth and the input side rotation speed Nin. In block 61, Vout is Te, Ni
It is calculated as a function g (Te, Nin, Nout) of n and Nout. Vo
ut 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 hinder the torque transmission by the belt 11, and the power loss and the durability reduction of the belt due to the excessive line pressure are prevented. FIG. 7 is a flowchart of the algorithm of the present invention. In step 68, the throttle opening θth is read. At step 69, the target value Nin ^* of the input side rotation speed Nin of CVT4
Is calculated as a function of the throttle opening θth. Step
At 70, engine output torque Te and cooling water temperature Tw are read as operation data. In step 71, the variation width Δin of the comparative rotation speed in is calculated as a function f (θth, Te, Tw) of θth, Te, Tw. In step 72, the speed ratio e of CVT4 is the minimum value e mi
It is determined whether or not n <e <maximum value e max. If it is correct, the process proceeds to step 76, and if not, the process proceeds to step 77. At step 76, the input side rotation speed Nin to determine Nin ^* is greater than, Nin> Nin ^* a long if the process proceeds to step 78, Nin ≦ Nin ^* a long if skips step 78 (flow-through) to. At step 77, 0 is substituted for Δin. In step 78, -ΔNin is substituted for ΔNin. Step 79
Now, substitute in + ΔNin for in. Therefore, if Nin is larger than the target value Nin ^* , the comparative rotation speed
in is reduced by the change amount ΔNin calculated in step 71,
If Nin is less than or equal to the target value Nin ^* , the comparative rotation speed in increases by the change amount ΔNin calculated in step 71. Further, if e ^* ≦ e min or e ^* ≧ e max, ΔNin is set to 0 in step 77 and in is not changed in step 79. In such a case, even if you change in, CVT4
This is because it cannot follow the change of in. In step 80, the deviation ΔNin between Nin and in is calculated.
In step 81, the voltage Vin sent to the amplifier 50 for the flow control valve is
Is calculated from Vin = K · ΔNin. However, K is a constant. As a result, Nin is feedback-controlled with the comparative rotation speed in as the target value. In step 82, the time count Δt is reset. The time count Δt counts the elapsed time based on the input of the clock pulse. In step 83, it is determined whether or not Δt ≧ feedback interval Δt1, and if Δt ≧ Δt1, the process returns to step 68, and if Δt <Δt1, the process proceeds to step 84. At step 84, Δt is counted, and the process returns to step 83. Thus, when the comparative rotation speed in is newly set in step 79, Nin is equal to the constant feedback interval Δt1.
Feedback control is performed to in, and when time has elapsed by Δt1, a new comparative rotation speed in is set again in step 79. Therefore, the comparative rotation speed in becomes as shown in FIG. 8 (a) when Nin ≦ Nin ^{* and} as shown in FIG. 8 (b) when Nin> Nin ^* . In this way, Nin moves to Nin ^* at a linear speed.

【The invention's effect】

As described above, according to the present invention, since the controlled variable is feedback-controlled with the 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 followability And the responsiveness can be improved.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the line pressure and the oil temperature of CVT and the speed change speed, and FIG. 2 is a graph showing the time change of the engine speed when the target value of the engine speed changes stepwise. FIG. 3 is a configuration diagram of an embodiment of the present invention, FIG. 4 is a graph showing a relationship between an intake system throttle opening and a target input side rotation speed, and FIG. 5 is a target input rotation speed and a comparative rotation. FIG. 6 is a block diagram of an embodiment of the present invention, FIG. 7 is a flow chart of the algorithm of the present invention, and FIG. 8 is a comparative rotation. It is a figure which shows the time change of speed. 1 ... Engine body, 4 ... CVT, 18 ... Throttle sensor, 30 ... Flow control valve, 38 ... Electronic control unit.

Claims (1)

[Claims] 1. A target engine speed is set as a function of the amount of depression of an accelerator pedal, and is controlled through a speed ratio control of a continuously variable transmission so that the actual engine speed matches the target engine speed. In a power transmission device for a step-shift type vehicle, based on the target engine rotation speed, apart from the target engine rotation speed, linearly changes with time toward the target engine rotation speed to linearly change the actual engine rotation speed. A means for setting a comparative rotation speed for changing, and a means for feedback-controlling the engine rotation speed with the comparison rotation speed as an immediate target value to linearly bring the engine rotation speed close to the target engine rotation speed. A power transmission device for a continuously variable vehicle, comprising: