JPS60125449A - Controller for continuously variable transmission of vehicle - Google Patents

Abstract

PURPOSE:To prevent hunting, by reducing the speed ratio of a continuously variable transmission if desired, to provide a hysteresis in the changeover of stationary running control and uphill running control. CONSTITUTION:An aimed engine revolution speed No in the stationary running of a vehicle is set so that the feeling and performance of running, which correspond to the speed V of the vehicle, and a good fuel efficiency are established together. Even if the person running the vehicle requests a sharp acceleration, a continuously variable transmission (CVT) 10 is changed over from stationary running control to uphill running control, provided that the differentiated value V' of the vehicle speed V is not higher than a prescribed level V'a1, so that the aimed engine revolution speed No is gradually increased by every prescribed quantity from a point X1 to another X2 as shown by a dotted line X1-X2. When the requested acceleration has become lower than a prescribed level or the rate of the rise in the vehicle speed V has become higher than a precribed level, after the start of the decrease in the speed ratio (e) of the transmission 10, the speed ratio is returned to a value corresponding to an aimed engine revolution speed level in the normal running of the vehicle.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a control device for a continuously variable transmission (hereinafter referred to as [CVT J]) used as a power transmission device of a vehicle.
In particular, the present invention relates to a control device that can accelerate a vehicle well.

Background Art In a CVT control device, the target engine rotation speed NO is set as a function of vehicle operating parameters such as throttle opening θ and vehicle speed V, and the actual engine rotation speed Ne is set to the target engine rotation speed N'o. The CVT is controlled, but with conventional control devices, the target engine speed at low vehicle speeds is required to achieve both driving feeling and driving performance according to vehicle speed and good fuel consumption. The speed NO was set to a low value.

Therefore, even if the driver tries to accelerate the vehicle by depressing the accelerator pedal from a low speed state on a steep road, etc.,
There was a problem in that the amount of increase in the engine rotational speed Ne was small, the increase in engine output was small, and good acceleration did not occur.

Therefore, the present applicant reduces the speed ratio e of the CVT when the increase in vehicle speed V is small even though acceleration of the vehicle is required in the previous Japanese Patent Application No. 58-126110.
This increases the driving torque and provides good acceleration C
A VT control device has been disclosed. However, it is not possible to change the CVT from steady-state control (hereinafter referred to as "steady-state control") to control such as when climbing a mountain (hereinafter referred to as "hill-climbing control") that increases drive torque, or from climbing control to steady-state control. There is a phenomenon known as control hunting when a common condition is changed from being satisfied to not being held or vice versa.

As such a common condition, for example, if it is set that the throttle opening degree of the intake system is 0 or more than the predetermined value 01,
Even if the driver intends to press hard on the accelerator pedal, he or she may unconsciously release the accelerator pedal a little, and the engine speed Ne changes frequently due to switching between steady control and uphill control, causing a loss of driving sensation. It's getting worse. In addition, changing the target engine speed NO from steady control to uphill control or vice versa at once when switching between steady control and uphill control will cause a sudden change in engine speed Ne. Driving sense has deteriorated.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a CVT control device that can prevent hunting caused by switching between climbing control and acceleration control and provide a good driving feel.

In order to achieve this object, the CVT control device of the present invention operates the continuously variable transmission when the driver's acceleration request for the vehicle is greater than or equal to a predetermined value A1 and the rate of increase in vehicle speed V is less than or equal to a predetermined value B1. After the speed ratio reducing means for reducing the speed ratio C and the speed ratio reducing means starts to reduce the speed ratio e, the driver's acceleration request for the vehicle becomes less than a predetermined value A2 (however, A2 < AI) or the vehicle speed ■ The engine is equipped with a speed ratio return means for returning the speed ratio e to a value corresponding to the target engine rotational speed in a steady state when the rising speed of the engine exceeds a predetermined value B2 (where B2 > Bl).

As a result, hysteresis is provided in switching between steady control and climbing control, so frequent switching due to unconscious actions of the driver can be avoided, and driving sensation can be improved.

In a preferred embodiment, the speed ratio reducing means and the speed ratio returning means gradually change the speed ratio e. Therefore, the engine rotational speed Ne changes smoothly, and the driving feeling when switching between steady control and climbing control is improved.

Preferably, the speed ratio reducing means and the speed ratio returning means change the speed ratio e by changing the target engine rotational speed No, and change the driver's acceleration request for the vehicle from the intake system throttle opening O or its time change from 0 to 0. Detect.

For example, if the throttle opening degree O is a predetermined value (1σ01 or more), it is determined that the acceleration request for the vehicle is greater than the predetermined value A1, and the throttle opening degree 0 is determined to be a predetermined value θ2 (however, θ2
If the value is less than the predetermined value A2, it is determined that the driver's acceleration request for the vehicle is less than the predetermined value A2.

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

In FIG. 1, the CVTIO has an input shaft 12 and an output shaft 14 that are parallel to each other. The input shaft 12 is connected to the engine 16
The crankshaft 18 is provided coaxially with the crankshaft 18 , and is connected to the crankshaft 18 via a clutch 20 . The input pulleys 22a and 22b are provided opposite to each other, one input pulley 22a is provided as a movable pulley on the input shaft 12 so as to be movable in the axial direction and fixed in the rotational direction, and the other input pulley 22a is provided as a movable pulley in a fixed manner in the rotational direction. 22b is the input shaft 12 as a fixed pulley.
is fixed. Similarly, output side pulleys 24a, 24b
are also provided opposite to each other, one output side pulley 24'
A is fixed to the output shaft 14 as a fixed pulley, and the other output side pulley 24b is provided as a movable pulley to the output shaft 14 so as to be movable in the axial direction and fixed in the rotational direction. Opposing surfaces of the input pulleys 22a, 22'b and the output pulleys 24a, 24b are tapered, and the belt 26 with an isosceles trapezoid cross section is attached to the input pulleys 22a, 22b.
and the output pulleys 24a, 24b. The oil pump 28 pumps oil from the oil sump 30 to the pressure regulating valve 32.
send to The pressure regulating valve 32 is composed of an electromagnetic relief valve, and controls the line pressure of the oil passage 36 by changing the amount of oil released to the drain 34, and the line pressure of the oil passage 36 is controlled by the hydraulic cylinder of the output pulley 24b and the flow rate. It is sent to the control valve 38. The flow control valve 38 controls the flow rate of oil supplied from the oil passage 36 to the oil passage 40 connected to the hydraulic cylinder of the input pulley 22a, and the flow rate of oil discharged from the oil passage 40 to the drain 34. . Input side pulleys 22a, 22b and output side pulley 24 with respect to belt 26
The pressing forces of a and 24b are controlled by the oil pressure of the input side hydraulic cylinder and the output side hydraulic cylinder, and in relation to this pressing force, the input side pulleys 22a + 22b and the output side pulley 2
The radius of application of the belt 26 on the tapered surfaces of 4a and 24b changes, and as a result, the CVTIO speed ratio e (= No.
ut/Nin.

However, Nout is the rotational speed of the output shaft 14, Nin is the rotational speed of the input shaft 12, and in this embodiment, Nin=engine rotational speed Ne. ) changes. In order to suppress the cantering loss of the oil pump 28, the line pressure of the output side hydraulic cylinder is set to the minimum necessary value that can avoid slipping of the belt 26 and ensure power transmission. The speed ratio e is controlled by hydraulic pressure. Note that the hydraulic pressure of the input side hydraulic cylinder ≦ the hydraulic pressure of the output side hydraulic cylinder, but since the pressure receiving area of the input side hydraulic cylinder > the pressure receiving area of the output side hydraulic cylinder, the pressing force of the input side pulleys 22a and 22b is calculated from the output side pulley. The pressing force can be made larger than that of 24a and 24b. The input side rotation angle sensor 42 and the output side rotation angle sensor 44 are connected to the input shaft 12 and the output shaft 1, respectively.
detect the rotational speed N l n + N Ou j of 4,
Water temperature sensor 46 detects the temperature of the cooling water of engine 16. An accelerator pedal 50 is provided in the driver's seat 48, a throttle valve in the intake passage is interlocked with the accelerator pedal 50, and a throttle opening sensor 52 detects zero throttle opening. A shift position sensor 54 detects the shift range of a shift lever located near the M seat.

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

The address data bus 56 is connected to the CPU 58. RAM 6
0. ROM62.1/F (interface) 64.
An A/D (analog/digital converter) 66 and a D/A (digital/analog converter) 68 are interconnected. r/F 64 is the input side rotation angle sensor 42
, the output side rotation angle sensor 44, and shift 1 to upper position 54, the A/D 66 receives analog signals from the water temperature sensor 46 and the throttle opening sensor 52, and the D/A '68 A pulse signal is output to the pressure regulating valve 32 and the flow rate control valve 38.

FIG. 3 illustrates the characteristics of the target engine rotational speed No.

The solid line is the characteristic of the target engine rotation speed No in steady state, and the target engine rotation speed No in steady state is set as a function f(G, V) of throttle opening degree O and vehicle speed ■. Target engine rotation speed N during steady state.

is set to achieve both driving sensation and performance according to the vehicle speed V and a good fuel consumption rate, and is an increasing function of the vehicle speed V (Vl>V2>, V3>V4). . The driver's acceleration request for the vehicle can be detected, for example, from the throttle opening θ, and even though the throttle opening θ is greater than or equal to the predetermined value 01, that is, even though the driver is requesting strong acceleration. First, when the time differential value 9 of the vehicle speed V is less than the predetermined value Val, that is, when the rate of increase in the vehicle speed V is small, the CVTIO is switched from steady control to uphill control, and the target engine rotational speed N
O is gradually increased by a predetermined amount from xl to x2, for example, as shown by the broken line XI-X2. Target engine rotational speed N by uphill control.

'2 rise is 6<e2 (however, θ2<01) or 0
This continues until ≧Va2. 0〈02 or■≧
After reaching Va2, the target engine speed NO is No=f(
0, V).

FIG. 4 is a flowchart of the target engine rotational speed calculation routine. When 0>θl and shift*al conditions are met, the climbing control flag F is set, and each time T1&l elapses, the target engine rotational speed No becomes ΔNot.
It is raised step by step, that is, gradually. After the start of pitching control, if the condition θ<02 or V≧Va2 is satisfied,
The target engine rotational speed No. is gradually lowered by ΔNod every time r21 (%) elapses until the target engine rotational speed No. = f(0, V). , the uphill control flag F is reset.The reason why the timer is reset in step 82.90 is that if time TI has elapsed since the uphill control flag F was set and NO was increased by ΔNoi. This is to increase No by ΔNoi, and the reason why the timer is reset in steps 102 and 110 is when 002 or Q
Time is T from when the condition of ≧Va2 is first established and from when NO is lowered by ΔNod after that time.
This is to lower NO by ΔNod after 2 elapses. Flag G is set to 02 or %l after the start of pitching control.
> V B This is set to detect when the condition of 2 is satisfied for the first time.

Each step in FIG. 4 will be explained in detail. In step 72, the value of the uphill control flag F is determined, and if it is F-o, step 7
If the result is F-1, the process advances to step 92. In step 74, the throttle opening degree 0 is compared with a predetermined value 01,
If o<θ1, the process proceeds to step 76; if θ≧el, the process proceeds to step 78. In step 76, the target engine rotation speed N is determined.

The value f(El, V) during steady control is substituted into . As a result, CVTIO is controlled by steady-state control. In step 78, the time differential value ψ of the Of speed V is compared with a predetermined value Val, and if *>*a+, the process proceeds to step 76, where V≦V
If it is al, proceed to step 8o. At step 80, flags F and G are set. In step 82, the timer is reset. In step 84, the timer measurement time T and the predetermined time T1 are compared, and if T<TI, step 86
If T≧T1, the process advances to step 88. In step 86, the target engine rotational speed No. is held at the value at the previous execution of the routine. In step 88, No is ΔNof
only to rise. In step 90, the timer is reset.

In step 92, the throttle opening degree θ is compared with a predetermined value 02, and if 0>02, the process proceeds to step 94, and 0<θ2
If so, proceed to step 98. In step 94, the vehicle speed ■
If the ratio Va2 is established between the time differential value ■ and the predetermined value Va2, the process proceeds to step 98. In step 96, the target engine rotational speed NO calculated at the previous execution of this routine is read. In step 98, the value of flag C is determined, and if G=1, the process proceeds to step 100, and if G-0, the process proceeds to step 104.

At step 100, the flag G is reset to 1-. In step 102, the timer is reset to 1-. Step 104
Now, compare the timer measurement time T and the predetermined time 1゛2,
If T<T2, proceed to step l()6; if T≧12, proceed to step 108.In step 106, the target engine rotation speed NO is held at the value at the previous execution of the routine.In step 108, NO .

is lowered by ΔNod. In step 11O, the timer is reset. In step 112, the target engine rotation speed No. is compared with the value r(e, v) during steady control, and if No>
If f(θ,■), the routine is terminated, and No≦f(
θ+V), the process advances to step 114. Step 11
In step 4, flag F is reset.

[Brief explanation of the drawing]

Fig. 1 is a diagram schematically showing the entire CVT, Fig. 2 is a block diagram of the electronic splitter device, Fig. 3 is a graph illustrating the characteristics of the target engine rotation speed, and Fig. 4 is the target engine according to the present invention. It is a flowchart of a rotational speed calculation routine. 10...CVT, 44...Output side rotation angle sensor, 5
2... Throttle opening sensor, 58... CPU 1st
Figure 0

Claims (1)

[Claims] ``Continuously variable transmission for a vehicle that sets a target engine rotation speed as a function of vehicle operating parameters and controls the continuously variable transmission so that the actual engine rotation speed becomes the target engine rotation speed.'' In the control device, a speed ratio reducing means for reducing the speed ratio e of the continuously variable transmission when the driver's acceleration request for the vehicle is equal to or higher than a predetermined value A1 and the rate of increase of the vehicle speed V is below the predetermined value; After the speed ratio reducing means begins to reduce the speed ratio e, the driver's acceleration request for the vehicle becomes less than the predetermined value A2 (where A2 < AI) or the rate of increase in the vehicle speed becomes less than the predetermined value B2 (however, B2>old). ) A control device for a continuously variable transmission for a vehicle, comprising a speed ratio return means for returning the speed ratio e to a value corresponding to a target engine rotation speed in a steady state when the speed ratio e reaches or exceeds the target engine speed. , 2 The speed ratio reducing means and the speed ratio returning means are configured to adjust the speed ratio e
The control device according to claim 1, characterized in that the speed ratio reducing means and the speed ratio returning means change the speed ratio e by changing the target engine rotational speed. A control device according to claim 1, characterized in that: 4. The control device according to claim 1, wherein the speed ratio reducing means and the speed ratio returning means detect the driver's acceleration request for the vehicle from an intake system throttle opening degree of 0 or its time change 6. . 5. The speed ratio reducing means has a throttle opening degree O of a predetermined 4 ft.
e + or more, it is determined that the driver's acceleration request for the vehicle is greater than or equal to the predetermined value A1, and the speed ratio return means determines that the throttle opening degree O is equal to or greater than the predetermined value A1 [6θ2 (however, 02
71. The control device according to claim 1, wherein the control device determines that the driver's acceleration request for the vehicle is equal to or less than the predetermined value A2.