JPS59212563A - Method of controlling stepless speed change gear of vehicle - Google Patents

Abstract

PURPOSE:To improve fuel consumption without hindrance on responsiveness at the time of acceleration by fixing the speed ratio when a suction system throttle opening is small and engine rotation speed is low. CONSTITUTION:When a suction system throttle opening theta is small and input-side rotation speed Nin is low, the speed changing rate of a CVT4 is made zero and speed change ratio (E) is fixed. Thereby, when the movement of the throttle opening theta is small, poorer responsiveness of an engine can be allowed more or less, preventing the deterioration in the CVT transmitting efficiency by speed change and improving the fuel cost. Also, when the throttle opening theta is large, deterioration of the responsiveness can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling a continuously variable transmission (hereinafter referred to as "CvT") used as a power transmission device for a vehicle, and particularly to a method for controlling the speed change of a CVT.

CVT has speed ratio e (=output side rotational speed Nout /
The input side rotational speed N1n) can be continuously controlled and is used in vehicles as a power transmission device with excellent fuel consumption efficiency. In such a CVT, as shown in Fig. 7, the gear is shifted as the gear shift speed a (absolute value of the value de/dt obtained by differentiating the speed ratio e with respect to time t) increases, but for this shift, the muscular transmission is In some cases, the efficiency deteriorates and fuel consumption efficiency worsens.

An object of the present invention is to provide a CvT control method that can improve fuel consumption efficiency without impairing responsiveness during acceleration.

In order to achieve this object, the present invention provides that when the intake system throttle opening is small and the engine speed is low, C
The speed ratio e of VT is fixed.

In other words, if the movement of the throttle opening is small, a slight deterioration in engine responsiveness will cost ¥1. CV by changing speed
To prevent deterioration of T transmission efficiency and improve fuel efficiency. When the throttle opening is large, control is performed using the original speed change performance indicator so as not to impair responsiveness.

Embodiments of the present invention will be described with reference to the drawings.

Ru. A pair of input side disks 6a and 6b are provided facing each other, and one input side disk 6a4J input shaft 5
The other input side disc 6b is fixed to the input shaft 5 so as to be relatively movable in the axial direction. Also, a pair of output side disks 7a.

7b are also provided facing each other, one output side disk 7a is fixed to the output shaft 8, and the other output side disk 7b
is provided on the output shaft 8 so as to be movable in the axial direction. The belt 9 has an isosceles trapezoidal cross section, and the input side disk 6
a, 6b and the output side disks 7a+7b.

The opposing surfaces of the input side disks 6a, 6b and the opposing surfaces of the output side disks 7a+7b are formed into tapered cross sections so that the distance between them increases as they proceed radially outward. The input side and output side disks 6a in relation to the increase or decrease of the distance between the opposing surfaces.

The radius of engagement of the belt 9 at 6b, 7a, and 7b increases or decreases, and the speed ratio and transmission torque change.

The oil pump 14 sends oil sucked from the oil sump 15 to the pressure regulating valve 16. The linear solenoid type pressure regulating valve 16 controls the amount of oil discharged to the drain 17 to control the line pressure of the oil passage 18 . The oil passage 18 is connected to a hydraulic cylinder of the output side disc 7b. The linear solenoid type control valve 19 increases the pressing force Ne) between the input side disks 6a + 6b.
The flow cross-sectional area between the oil passage 20 and the oil passage 18 to the hydraulic cylinder a is increased, the connection between the oil passage 20 and the drain 17 is cut off, and the pressing force between the input side discs 6a + 6b is reduced. When reducing the speed ratio, the oil passage 18
and 20, and controls the flow cross-sectional area between the oil passage 20 and the drain 17. Rotation angle sensor 23, 2
4 detects the rotation speed Nin + Nout of the input side disk 6b and the output side disk 7a, respectively. The cylinder oil pressure of the output side disk 7b, that is, the line pressure, is controlled to the minimum oil pressure that can ensure torque transmission without the belt 9 slipping, thereby suppressing drive loss of the pump 14. CVT due to the flow rate of oil to the input side disc 6a
A speed ratio of 4 is controlled. Although the cylinder oil pressure of the output side disk 7b≧the cylinder oil pressure of the input side disk 6a, the pressure receiving area of the cylinder piston is on the input side <output side, and a speed ratio of 1 or more can be realized. Water wetness sensor 2
5 detects the cooling water temperature of the engine 1.

The throttle opening sensor 26 detects the opening of an intake system throttle valve that is linked to the accelerator pedal 27 .

The shift position sensor 28 is located at a shift lever near the seat 29.
Detects the range of

FIG. 2 is a block diagram of the electronic control device.

CPU 32, RAM 33, ROM 34, I
/F (interface) 35, A/D (analog/digital converter) 36, and D/A (digital/analog converter) 37 are connected to each other by bus 38. The output pulses of the rotation angle sensors 23 and 24 and the shift position sensor 28 are sent to the interface 35, the analog outputs of the water wetness sensor 25 and the throttle opening sensor 26 are sent to the A/D 36, and the output of the D/A 37 is It is sent to the pressure regulating valve 16 and the flow rate control valve 19.

FIG. 3 is a control block diagram of the CVT 4.

At block 44, the throttle is adjusted from O to CVT.
A target value Nin' of the input side rotational speed N1n (=engine rotational speed Ne) of No. 4 is calculated. In the CVT 4, the required horsepower of the engine 1 is set as a function of the throttle opening 0, and the engine rotation speed Nc that achieves each required horsepower with the minimum fuel consumption is determined by the input side rotation speed Ni at the current throttle opening θ.
The target value of n is determined as Nin'. Block 46 is N
The target speed ratio e' is increased or decreased by Δe until in reaches Nin'. However, the change amount Δe is a positive value. The initial value of the target speed ratio e' is the actual speed ratio e, 80 is a predetermined amount, and if Nin <Nin', -Δe, Nin
>N i n', +Δe is selected.

In block 48, a feedback cane is calculated from the deviation of the actual speed ratio e from the target speed ratio e'. The feedback cane is sent to the flow control valve 19 via the flow control amplifier 50, and the speed ratio e of the CVT 4 is controlled. In block 52, the shaft torque Te of the engine l is calculated from the blade entry side rotational speed Nin and the throttle opening degree θ. block 5
4, the line pressure is subtracted as a function of the transmission torque of the CVT 4. The transmission torque of the CVT 4 is a function of the shaft torque Te of the engine 1, the input side rotational speed Nin, and the output side rotational speed Nout. The output of the block 54 is sent to the pressure regulating valve 16 via the pressure regulating valve amplifier 56, and the line pressure of the CVT 4 is controlled.

FIG. 4 is a flowchart of a routine for executing control according to the control block diagram of FIG. 3. The outline of the control is as already explained in FIG. Note that the upper and lower limits of the target speed ratio e' are emax and emin, and the flow rate side 'a voltage as the input voltage of the flow rate control valve 19 is K(e'-e) (K is a constant), and the adjustment The pressure regulating valve control voltage as the input voltage of the pressure valve 16 is g (Te
+ Nz n +Nout ). Step 60
, 62.64, the throttle opening is 0 and the input side rotation speed is N.
in, read the output side rotation speed Nout, and step 6
In step 6, the target input side rotational speed Nin' is calculated. In step 68, Nin and Nin' are compared and Nin =
If Nin', e' is held in step 70, and if Ntn<Nin', e' is held in step 72.
is decreased by Δe, and if Nin>Nin', e' is increased by Δe in step 76. Step 7
In step 3.74, the lower limit of e' is limited to emin, and in steps 78 and 80, the upper limit of e' is limited to emax. At step 82, the flow rate control voltage is calculated, at step 84, the engine shaft torque Te is calculated, and at step 86, the pressure regulating valve control voltage is calculated.

FIG. 5 shows the relationship between the intake system throttle opening degree 0, the input side rotational speed Nin (=engine rotational speed Ne), and the shift speed & in the present invention.

As already defined, the shift speed is the absolute value 1de/dtl of the time differential value de/dt of the speed ratio e, and the third
Corresponds to block 46 of the figure and Δe in step 72.76 of FIG. As is clear from Figure 5, 0
In the region of <e l+ Nin < Nin1, that is, in the region of light weight, 5=0 is selected, and in other regions, 2
=x (where X is a predetermined value) is selected. When the intake system throttle opening θ is small and the engine rotation speed Ne (=
If the input side rotational speed Nin) is low, some deterioration in engine response is allowed, and by setting only the shift speed to 0, a good transmission efficiency as shown in Fig. 7 is ensured and fuel consumption is reduced. Improve efficiency. Note that during the period of shift speed 20, the vehicle speed V increases only due to an increase in the engine rotation speed Ne.

FIG. 6 is a flowchart of a routine for calculating the shift speed 5 according to the relationship shown in FIG. At steps 92 and 94, the throttle opening degree is 0, the input side rotational speed Nin is determined, and the predetermined value θ1. Compare θ1 and Nin1.
If <Nin1, the process advances to step 96 and O is substituted for only the shift speed; otherwise, the process advances to step 98 and X is substituted for only the shift speed.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of a CVT to which the present invention is applied, FIG. 2 is a block diagram of an electronic control device, and C VT ;l;! according to the second control block diagram. A flowchart of the control routine, FIG. 5 is a diagram showing the relationship between the intake system throttle opening, the input side rotation speed, and the shift speed in the present invention,
FIG. 6 is a flowchart of a quick speed fl' calculation routine according to the relationship shown in FIG. 5, and FIG. 7 is a graph showing the relationship between shift speed and transmission efficiency in a CVT. 1... Engine, 4... CVT, +9... Flow rate control valve, 23... Rotation angle sensor, 26... Throttle opening sensor. Special order, 8F person Toyota Motor Corporation Figure 7 Shift speed δ

Claims (1)

[Claims] A control method for a continuously variable transmission for a vehicle, characterized in that a speed ratio is fixed when the intake system throttle opening is small and the engine rotation speed is low.