JPH0450440A - Engine control method for vehicle equipped with cvt system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control method for a vehicle equipped with a CVT system.

(Conventional technology and issues to be solved) CV that can control the gear ratio steplessly as an automatic transmission
T (Continuously Variable T
In a vehicle equipped with a CVT transmission system, the torque that can be transmitted between the two pulleys of the CVT transmission mechanism (hereinafter referred to as "transmission torque") is:
The belt pressing force that presses the belt hooked between these pulleys is determined by the force, and if more torque is input, the belt will slip, which not only will not accelerate the vehicle, but will also cause the belt to heat up, reducing its durability. It causes sexual deterioration etc.

In conventional CVT systems, CVT input torque was controlled without detecting belt slip.
The slippage at the CVT belt was sometimes large. If slippage occurs in the belt, its durability will be extremely deteriorated. Therefore, in order to prevent the belt from slipping, even if the input torque of the CVT is small, a large hydraulic pressure is applied to the pulley of the CVT to press the belt. As a result, there is also the problem that the transmission efficiency of the CVT is poor.

The present invention has been made in view of the above points, and is a CVT that detects the oil pressure applied to the CVT pulley and limits the output torque of the engine so as to prevent the belt from slipping.
The purpose is to provide an engine control method for vehicles equipped with the system.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, the hydraulic pressure applied to the CVT pulley of a CVT system is detected, and the CVT
The transmittable torque of the pulley is calculated, the output torque of the engine is determined, the required reduced torque of the engine is determined from both of these torques, and the air-fuel ratio of the engine is determined based on the required reduced torque and a parameter representing the operating state of the engine.・The ignition timing is determined to limit the output torque of the engine.

(Operation) The required reduced torque of the engine is determined by subtracting the transmittable torque of the CVT pulley from the output torque of the engine. The air-fuel ratio and ignition timing of the engine are determined based on this requested reduction torque and parameters representing the engine operating state such as the engine rotational speed and intake air amount, and the output torque, that is,
The input torque of the CVT is limited, and the pressing force of the CVT pulley is set to be low.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an engine and a power transmission system of a vehicle equipped with a CVT system according to the present invention. The output shaft of the torque converter 4 is connected via a planetary gear 5 to a drive pulley 7 of a V-belt drive continuously variable transmission (hereinafter referred to as "CvT") 6, and the drive pulley 7 is connected via a V-belt 9. is connected to the driven pulley 8, and the driven pulley 8
The output shaft 10 of is connected to left and right axles 13, 14 via a gear system 11 and a differential mechanism 12.

The drive pulley 7 and the driven pulley 8 are connected to the hydraulic chamber 1, respectively.
5.16, and these hydraulic chambers 15 and J6 are
It is connected to a hydraulic control valve system 17. The hydraulic control valve system 17 continuously varies the pulley diameters of the drive pulley 7 and the driven pulley 8 by controlling the hydraulic pressure in the hydraulic chamber 15.16 based on a control signal from the CVT computer 41 that controls the CVT system. At the same time, the pressing applies force to the belt 9 that is stretched between the drive pulley 7 and the driven pulley 8.

The intake manifold 20 of the engine 1 includes a surge tank 2
1 to an air cleaner 22.

Spark plug 2 installed in the cylinder head of engine l
3 is connected to an ignition coil 24, an injector 25 is provided downstream of the intake manifold 20, and a throttle valve 26 is provided between the surge tank 21 and the air cleaner 22. The ignition coil 24 and injector 25 are connected to an engine control computer 40.

Hydraulic pressure sensors 30.31 are disposed in the hydraulic chambers 15.16 of the drive pulley 7 and driven pulley 8 of the CvT6, and an air flow sensor 32 for detecting the intake air amount of the engine 1 is disposed in the air cleaner 22. These oil pressure sensors 30, 31 and air flow sensor 32 are connected to an engine control computer 40. Further, an engine rotation speed signal is input to the engine control computer 40 from an engine rotation sensor (not shown). This engine control computer 40 controls the air-fuel ratio and ignition timing of the engine 1, and also controls the oil pressure sensor 15, 16 of the CvT6.
The engine 1 has a function of correcting the air-fuel ratio and ignition timing using the oil pressure signal from the engine as a parameter, and limiting the output of the engine 1.

Further, the CVT computer 41 receives a throttle opening signal from a throttle opening sensor (not shown) that detects the opening of the throttle valve 26, and an engine rotation speed signal from the engine rotation sensor. This CVT computer 41 estimates the output torque of the engine 1, that is, the input torque of the CvT 6 using the engine rotation speed signal and the throttle opening signal as parameters, and applies the hydraulic pressure to the hydraulic control valve system 17 so that the corresponding torque can be transmitted. It outputs a control signal to control the duty of the hydraulic pressure in each hydraulic chamber 15.16 of the drive pulley 7 and driven pulley 8 of the CVT 6, and controls the pressing force of the belt 9, that is, the hydraulic pressure applied to each of these pulleys 7.8. It has the function to

The operation will be explained below with reference to the flowchart shown in FIG.

The engine control computer 40 detects the operating state of the engine 1 based on the engine speed signal and the signal from the air flow sensor 32, calculates the optimal air-fuel ratio and ignition timing for the operating state, and calculates the fuel injection amount and injection timing. Then, the ignition timing and the like are determined, and the injector 25 is driven to inject fuel and the ignition plug 23 is ignited.

Engine control computer 40 includes oil pressure sensor 30.3
1 signal and measure the oil pressure in each hydraulic chamber 15 and 16 of the drive pulley 7 and driven pulley 8 of the CVT 6 (
Step 1) and calculate the transmittable torque Tp of the CVT 6 (Step 2). This transmittable torque Tp is
It is calculated based on a preset map or calculation formula using the detected oil pressure of each pulley 7.8 as a parameter (step 3). Incidentally, the oil pressure of the CVT pulley and the transmittable torque Tp are expressed as shown in FIG.

Next, the engine control computer 40 calculates the output torque Te of the engine 1 (step 4).

This engine output torque Te is calculated from a preset map based on the engine speed and intake air amount (
Step 5) is done. If the horizontal axis is the engine speed and the vertical axis is the suction efficiency, the equal engine torque curve is expressed as shown in FIG. Here, the intake efficiency is the intake air amount A
It is the value (A/N) divided by the engine rotation speed N. still,
For the engine output torque Te, a torque sensor may be attached to the crankshaft of the engine 1, and the output value of the torque sensor may be used.

Then, the engine control computer 40 compares the calculated engine output torque Te and the transmittable torque Tp to calculate the required reduction torque of the engine 1 (step 6). This required reduction torque is calculated by subtracting the transmittable torque Tp from the engine output torque Te (step 7).
)do.

Next, the engine control computer 40 corrects the engine output torque Te (step 8).

To correct the engine output torque Te, the target air-fuel ratio or ignition timing (or the amount of correction thereof) is determined from a preset map using the required reduced torque, engine speed, intake air amount, etc. as parameters (step 9). It is done by. At this time, if the transmittable torque Tp is greater than or equal to the sum of the engine output torque Te and the margin torque α (α is a constant) (Tp≧Te+α), the correction of the air-fuel ratio or the ignition timing is set to zero. Moreover, the transmittable torque Tp is
If the torque is smaller than the sum of the engine output torque Te and the margin torque α (Tp<Te×α), slippage of the belt 9 occurs, so the engine output torque Te is corrected as described above.

Then, the engine control computer 40 executes control of the target air-fuel ratio or ignition timing determined in step 9 (
Step 10).

In the above embodiment, the engine control computer 40 takes in the signals from the oil pressure sensors 30 and 31 and controls the C.
Hydraulic pressure of VT pulley, i.e. drive pulley 7 of CVT6,
Although the oil pressure in each oil pressure chamber 15, 16 of the driven pulley 8 is measured, the present invention is not limited to this. (The CVT oil pressure may be measured by the CVT computer 4I and transmitted to the engine control computer 40. .Also,
The data transmitted at this time may be data obtained by converting oil pressure into transmittable torque.

(Effects of the Invention) As explained above, according to the present invention, the hydraulic pressure applied to the CVT pulley of the CVT system is detected to calculate the transmittable torque of the CVT booster, and the output torque of the engine is determined, and the The required reduced torque of the engine is determined from both torques, and the air-fuel ratio and
By determining the ignition timing and limiting the output torque of the engine, when the oil pressure of the CVT pulley is low, a large torque that would cause the belt to slip even at 4 degrees will not be input, and the CVT pulley will It is possible to set the oil pressure at a low level without leaving much margin, and as a result, the durability of the CVT belt is improved, and the transmission efficiency of the CVT is improved, resulting in excellent effects such as improved fuel efficiency. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the engine and CVT system of a vehicle equipped with a CVT system to which the engine control method for a vehicle equipped with a CVT system according to the present invention is applied, and FIG. 2 is a flowchart showing the procedure for implementing the control method of the present invention. , FIG. 3 is a characteristic diagram showing the relationship between hydraulic pressure of the CVT booster and transmittable torque, and FIG. 4 is a characteristic diagram showing the equal torque curve of the engine. 1...Engine, 3...Automatic transmission, 6...CV
T, 7...Drive pulley, 8...Driven pulley, 15.16...Hydraulic chamber, 17...Hydraulic pressure control valve system, 30.31...Hydraulic pressure sensor, 32
... Air flow sensor, 40... Engine control computer, 41... CVT computer. 2nd Figure 3 Figure 4 Sword 3jL” - Nunshi Ikoma■

Claims (1)

[Claims] The hydraulic pressure applied to the CVT pulley of the CVT system is detected, the transmittable torque of the CVT pulley is calculated, the output torque of the engine is determined, and the required reduced torque of the engine is determined from both of these torques, and the required reduced torque is calculated. An engine control method for a vehicle equipped with a CVT system, characterized in that the air-fuel ratio and ignition timing of the engine are determined based on parameters representing the operating state of the engine, and the output torque of the engine is limited.