JPS616452A - Controller for continuously variable transmission for car - Google Patents

Abstract

PURPOSE:To improve drivability in reacceleration of a continuously variable transmission (CDT) by maintaining a high value free form speedy reduction to an aimed enging revolution speed when it is judged that acceleration is insufficient. CONSTITUTION:The intake throttle opening-degree theta, car speed V, and the engine revolution speed Ne are read-in, and an aimed engine revolution speed Ne' is calculated 58 from the opening degree theta. Then, a standard acceleration speed DELTAVa is calculated from the speed Ne and the aimed speed Ne', and compared 58 with the acceleration speed DELTAV of a car. If DELTAV<DELTAVa, acceleration is insufficient, and a timer (c) is cleared, and the lapse time Tc measured by the timer (c) is set zero. A limit means 38 which limits the reduction of the speed Ne to an aimed speed Ne' in the case when the absolute value of the deviation of the speed Ne with respect to the aimed speed Ne' becomes over a prescribed value is installed. Therefore, the speed Ne is controlled to the aimed speed Ne' from higher values, and acceleration performance can be improved.

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 CVTJ) used as a power transmission device for a vehicle.
In particular, it relates to control when a vehicle is mounted.

The conventional CVT is installed in the power transmission path of the engine, and the speed ratio e (= N
out/Nin (where Nout+Nin is the output side and input side rotational speed of the CVT) is controlled. For example, in Japanese Patent Application No. 57-67362 filed by the present applicant, regardless of whether the vehicle is in steady state or acceleration, the target engine rotational speed is set to be an engine that achieves the required engine output in steady state with a fuel consumption rate of at most 4\B. The rotation speed is set. Therefore, during acceleration, the acceleration performance until the engine rotational speed reaches the target engine rotational speed and the engine produces the necessary output tends to deteriorate.

Particularly when driving on a hill, the amount of accelerator pedal depression increases, the amount of increase in engine rotational speed also increases, and responsiveness deteriorates, so the driver must set the target engine rotational speed separately from the D (drive) range. Currently, the range is shifted to the 2nd (second) range, which is the preset range. This makes the operation complicated and is also disadvantageous in terms of fuel consumption.

Tokukai Akira! Publication i8-1808β4 teaches to detect the acceleration of the vehicle and increase the gear ratio of the CVT (the gear ratio is the reciprocal of the speed ratio e) if the acceleration is small, but if the acceleration is insufficient. , does not disclose any control that is advantageous for the next re-acceleration in the period until the next re-acceleration occurs.

Purpose An object of the present invention is to provide a CVT control device that can improve drivability during re-acceleration without using a low speed range such as the second range.

Structure To achieve this object, the present invention provides a control device for a vehicle CVT that controls the speed ratio of a CVT so that the engine rotational speed becomes a target engine rotational speed, comprising: acceleration detection means for detecting acceleration of the vehicle. , a reference acceleration calculation means for calculating a reference acceleration, a determination means for determining that acceleration is insufficient if the acceleration is higher than the reference acceleration when the absolute value of the deviation of the engine rotation speed from the target engine rotation speed is less than a predetermined value; limiting means for limiting the reduction of the engine rotational speed to the target engine rotational speed when the absolute value of the deviation of the engine rotational speed from the target engine rotational speed becomes less than or equal to a predetermined value after it is determined that the acceleration is insufficient; I'm thinking about it.

If the action and effect acceleration is determined to be insufficient, the engine rotation speed will quickly drop to the target engine rotation speed even if the absolute value of the deviation of the engine rotation speed from the target engine rotation speed exceeds a predetermined value. It is held at a high value without any problems. Therefore, at the time of the next re-acceleration, the engine rotational speed can approach the target engine rotational speed from a high value, so that the required engine output can be produced quickly and good acceleration performance can be obtained.

In the present invention, since there is no need to shift to a low speed range, the operation becomes simple. In addition, in the present invention, even during acceleration, the engine rotation speed is operated at the target engine rotation speed of the D range or a value close to it for a longer period of time, so the fuel consumption rate is higher than when the engine is operated continuously in the low speed range. will improve.

In a preferred embodiment 7Iiii, the limiting means is a means for suppressing a decrease in engine speed within a predetermined time after the absolute value of the deviation becomes less than a predetermined value, and the reference acceleration is a function of the intake throttle opening and the vehicle speed V. It is.

Preferably, the limiting means is a means for correcting the target engine rotational speed within a predetermined period of time relative to the original value, or the limiting means is a means for correcting the value of a coefficient that determines the shift speed of the CVT.

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, and one of the input pulleys 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.
The other input side pulley 22b is a fixed pulley that connects the input shaft 1.
It is fixed at 2. Similarly, output side pulleys 24a, 2
4b are also provided oppositely, and one output side pulley 2
4a is fixed to the output shaft 14 as a fixed pulley, and the other output pulley 24b is provided as a movable pulley on the output shaft 4 so as to be movable in the axial direction and fixed in the rotational direction. Opposing surfaces of the input pulleys 22a, 22b and the output pulleys 24a, 24b are formed in a tapered shape, and the belt 26 with an isosceles trapezoidal cross section is connected to the input pulleys 22a, 22b.
2b and the output pulleys 24a, 24b. The oil pump 28 sends oil from the oil sump 3o to the pressure regulating valve 32. The pressure regulating valve 32 consists of an electromagnetic relief valve,
The line pressure of the oil passage 36 is controlled 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 control valve 3.
Sent to 8. The flow control valve 38 is connected to the input pulley 22a.
An oil line 36 to an oil line 40 connected to a hydraulic cylinder of
The supply flow rate of oil from the oil passage 40 to the drain 3
Controls the oil discharge flow rate to 4. The pressing force of the input pulleys 22a, 22b and the output pulleys 24a, 24b with respect to the belt 26 is controlled by the oil pressure of the input hydraulic cylinder and the output hydraulic cylinder, and the input pulleys 22a, 22b and the output are controlled in relation to this pressing force. The radius of engagement of the bell j-26 on the tapered surfaces of the side pulleys 24a and 24b changes, and as a result, the speed ratio e of the CVTIO changes.
(= Nout / 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 drive loss of the oil pump 28, the line pressure of the output side hydraulic cylinder is controlled to the minimum necessary value that can avoid slipping of the belt 26 and ensure power transmission, and is controlled by the oil pressure of the input side hydraulic cylinder. The speed ratio e is controlled. 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 as 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 detect the rotational speeds N l n + N Ou L of the input shaft 12 and the output shaft 14, respectively, and the water temperature sensor 46 detects the temperature of the cooling water of the 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. The shift position sensor 54 detects the shift range of the shift lever located near the driver's seat.

FIG. 2 is a block diagram of the electronic dissection 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. The I/F 64 receives pulse signals from the input side rotation angle sensor 42, the output side rotation angle sensor 44, and the shift position sensor 54, and the A/D 66 receives analog signals from the second seat sensor 46 and the throttle opening sensor 52. In response, the D/A 68 outputs a pulse signal to the pressure regulating valve 32 and the flow rate control valve 38.

FIG. 3 is a flowchart of the target engine rotational speed correction routine. Before explaining FIG. 3, FIGS. 4 and 5 related to FIG. 3 will be explained.

FIG. 4 shows the target engine rotational speed Ne' as a function of the intake throttle opening degree O. The engine rotation speed Ne at which the steady-state engine output corresponding to the intake throttle opening degree of 0 occurs at the minimum fuel consumption rate is set as the target engine mouth rotation speed Ne'.

FIG. 5 shows the basic acid acceleration ΔVa as a function of the intake throttle opening θ and the vehicle speed V. The basic acceleration ΔVa is set based on the acceleration of the vehicle that occurs in relation to θ and ■ when the vehicle is traveling on a horizontal plane of flat ground.

The actual acceleration ΔV of the vehicle decreases when traveling uphill at the same throttle opening degree of 0, but if ΔV<ΔVa', it can be determined that the acceleration of the heavy vehicle is insufficient.

The routine shown in FIG. 3 will be explained in detail.

First, the intake throttle opening .theta., the vehicle speed (2), and the engine rotation speed Ne are read (step 80), and the target engine rotation speed Ne' is calculated from O according to the graph of FIG. 4 (step 82).

Next, Ne and Ne'±Nex (Nex is, for example, 50 to +
Step 84), Ne'
−Nex < Ne
If l is less than the predetermined value, according to the graph in Figure 5,
The basic acceleration ΔVa is calculated from 0 (step 86), and the vehicle acceleration Δ■ and the basic acceleration ΔVa are compared (step 88). Furthermore, compare ΔV and ΔVa (Step 88), and if Δ■≧ΔVa, that is, if sufficient acceleration has occurred, reset the flag F (Step 90).
If Δv and ΔVa, that is, if the acceleration is insufficient, timer C is cleared, the elapsed time Tc measured by timer C is set to 0 (step 92), and flag F is set (step 94).

Note that the flag F is a flag set to indicate whether the acceleration is sufficient or insufficient when the engine rotational speed is stable.

If Ne is outside Ne':l:Nex, that is, if the absolute value of the deviation is greater than or equal to a predetermined value, flag F is determined (step 100), and Ne is changed from outside Ne'±Nex to Ne'±N.
Elapsed time Tc and predetermined time Tcx since the time it became within ex
(Tcx is about 5 seconds, for example). Compare step 10.
2) Compare Ne and Ne' (step 104).

When F=1, Tc<Tcx, and Ne>Ne', the value obtained from the following (+) equation is the target engine rotational speed N.
e' (step +06).

Ne −(tJe−Ne′)/K −
(1) However, in equation 1), Ne' is Ne' defined from FIG. 4, and K is a constant larger than 1.

Therefore, Ne' defined from equation (1) has a higher value than Ne' defined from the graph of FIG.

After all, the engine rotation speed N with respect to the target engine rotation speed Ne'
When the absolute value of the deviation of e is less than the predetermined value and the absolute value of the deviation becomes equal to or greater than the predetermined value, Ne' is defined from (1) 2, not from FIG. , is defined from Fig. 4 (a value higher than iM. Therefore, when re-acceleration occurs within this 1'cx, Ne moves from a high value to Ne' and quickly becomes Ne',
It can improve acceleration.

FIG. 6 shows a partially modified version of the routine shown in FIG.

That is, instead of step 106, 1(2/1(to 2
A step 106b is provided in which 2 is not modified, and a step 108 in which 2 is not modified is provided. K2 is a coefficient used in step]40 of FIG. speed ratio e
The amount of change in the flow rate in the flow rate control valve 38 is controlled in relation to the deviation Δe of If so, 2 becomes a small value in step +06b, so the shift speed of the CVT 10 increases, and the engine rotational speed Ne gradually decreases and is maintained at a value appropriately higher than Ne'.

FIG. 7 is a flowchart of a time interrupt routine executed at predetermined time intervals. The value of timer C is increased by a predetermined value (step 110), and the current vehicle speed Vn and the vehicle speed Vp at the previous execution of this routine are read (step 1).
12), set Vn-Vp as acceleration ΔV, step 114
), and finally substitute Vn for Vp (step 116).

FIG. 8 shows flowcharts 1 to 1 of the speed change drawing routine.

The flow rate control valve 38 is controlled so that the actual engine rotational speed Ne (=Nin) becomes the target engine rotational speed Ne', and the line pressure Pl is adjusted to the minimum value that can avoid slipping of the belt 26. Pressure valve 32 is controlled. To explain this routine in detail, read the input side and output side rotational speeds Nin+Nout of the CVTIO (step 124), and substitute Nout/Nin for the speed ratio e (step +26).
, Nout/Ne' is substituted for the target speed ratio e' (step 128). Next, the upper and lower limits of the target speed ratio e' are limited to eIIlax and cmin, respectively (steps 130, 132, 134, 136), and the deviation Δe is
'-e is substituted (Step 138), and 1.e- is substituted with 2.DELTA.e for the control voltage Va of the flow rate valve 38 (Step!40). However, Kl, 2 is a predetermined value, and the amount of oil supplied to the input hydraulic cylinder decreases by an amount corresponding to the deviation Δe, so that e approaches e'. Furthermore, the output torque Te of the engine is calculated based on the intake throttle opening degree 0, etc. Step 142)
It is calculated as a function f of e + N I n + N Q t (step 144). The function f corresponds to the torque at the output pulleys 24a, 24b. Va + V b calculated in this way are output to the flow rate control valve 38 and the pressure regulating valve 32, respectively (step 14
6).

Although the present invention has been described with reference to embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit of the claims.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire CVT, Fig. 2 is a block diagram of the electronic control unit, Fig. 3 is a flowchart of a target engine rotation speed correction routine, and Fig. 4 is a graph showing the characteristics of the target engine rotation speed. Fig. 5 is a graph showing characteristics of reference acceleration, Fig. 6 is a flowchart of a routine that is a partially modified version of the routine in Fig. 3, Fig. 7 is a flowchart of a time interrupt routine, and Fig. 8 is a flowchart of a CVT control routine. It is. lO...CVT, 42...Input side rotation speed sensor,
44...Output side rotating piece sensor, 58...cpu. Figure 1 Figure 2 Figure 4 Intake throttle opening θ Figure 5 Intake throttle opening θ

Claims (1)

[Scope of Claims] 1. A control device for a continuously variable transmission for a vehicle that controls the speed ratio of the continuously variable transmission so that the engine rotation speed becomes a target engine rotation speed, comprising: acceleration detection means for detecting acceleration of the vehicle; a reference acceleration calculation means for calculating a reference acceleration; a determination means for determining that acceleration is insufficient if the acceleration is smaller than the reference acceleration when the absolute value of the deviation of the engine rotation speed from the target engine rotation speed is less than a predetermined value; and limiting means for limiting the reduction of the engine rotational speed to the target engine rotational speed when the absolute value of the deviation of the engine rotational speed from the target engine rotational speed becomes a predetermined value or more after it is determined that the engine rotational speed is sufficient. A control device for a continuously variable transmission for a vehicle, characterized by the following. 2. After the absolute value of the deviation becomes less than a predetermined value, the limiting means
The control device according to claim 1, characterized in that the control device is means for suppressing a decrease in engine rotational speed within a predetermined period of time. 3. The control device according to claim 2, wherein the limiting means is a means for correcting the target engine rotational speed within a predetermined time period with respect to an original value. 4. The control device according to claim 2, wherein the limiting means is means for modifying the value of a coefficient that determines the speed change of the continuously variable transmission. 5. The control device according to any one of claims 1 to 4, wherein the reference acceleration is a function of an intake throttle opening and a vehicle speed V.