JPH01182139A - Engine control method for vehicle with continuously variable transmission - Google Patents

Abstract

PURPOSE:To quickly maximize the transmission ratio of a continuously variable transmission at the sudden braking time of a vehicle by compensating the angle of advance that the ignition timing of an engine is changed to increase the output of the engine when a sudden braking of the vehicle is detected. CONSTITUTION:When a brake switch 55 is in the ON position and the running speed of a vehicle is below the specified value and the deceleration speed of the vehicle is higher than the preset value, the state of the vehicle is detected as the braking state. At the time of the braking such that driving wheels are interrupted before the transmission ratio of a continuously variable transmission 16 reaches to the maximum, an ignition timing adjusting device 59 is operated to make an ignition of an engine at such an ignition timing that the angle of advance is increased by the angle corresponding to the deceleration speed of the vehicle. The rotation of an engine 10 is therefore increased by the specified value to increase the quantity of oil discharged from an oil pump 41, whereby maintaining the discharge pressure high. As a result, a line oil pressure is increased so that the transmission ratio readily reaches to the maximum if sudden braking is applied.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an engine control method for a vehicle equipped with a continuously variable transmission, and in particular to a technique for ensuring that the gear ratio of the continuously variable transmission reaches its maximum value during sudden braking of the vehicle. It is related to.

2. Description of the Related Art Vehicles are known that are equipped with a continuously variable transmission that continuously changes the speed of an engine and transmits the rotation to drive wheels.

In a vehicle equipped with such a power transmission device, normally, for example, the engine is operated steplessly based on the actual throttle valve opening and vehicle speed from a predetermined relationship that allows the engine to operate along the minimum fuel efficiency curve. The gear ratio of the transmission is controlled. Therefore, when the vehicle changes from a running state to a stopped state, the throttle valve is operated to the minimum opening and the vehicle speed decreases prior to stopping the vehicle, so there is no step change in relation to changes in these parameters. The gear ratio of the transmission is changed to the maximum value (maximum reduction state B).

However, if the vehicle is suddenly braked, the drive wheels will stop before the gear ratio of the continuously variable transmission reaches its maximum value, and when the vehicle restarts, the gear ratio of the continuously variable transmission will change. Because the power was not transmitted at its maximum value, there were cases where sufficient driving force could not be obtained.

On the other hand, as described in JP-A No. 61-52457, if the vehicle speed is lower than a predetermined constant value and a braking operation is being performed, the continuously variable transmission By changing the operating conditions of the pressure regulating valve that generates the line oil pressure that is applied to the secondary side hydraulic cylinder and increasing the line oil pressure by a predetermined amount, the speed at which the gear ratio changes is increased and the gear ratio changes to its maximum value. Techniques are disclosed that facilitate this.

Problems to be Solved by the Invention By the way, in vehicles equipped with the above-mentioned continuously variable transmission, the line oil pressure is increased by changing the operating conditions of the pressure regulating valve. The pressure valve regulates the output oil pressure of a hydraulic pump driven by the engine. However, as mentioned above, when it is necessary to increase the line oil pressure and change the gear ratio of the continuously variable transmission to the maximum value, the vehicle is suddenly stopped, the throttle operation is canceled, and the engine rotational speed decreases. As a result, the output hydraulic pressure of the hydraulic pump cannot be obtained sufficiently. For this reason, even if the line oil pressure is attempted to be increased by the pressure regulating valve, the output oil pressure of the hydraulic pump is not sufficient.
There were cases in which the gear ratio of the continuously variable transmission could not reach its maximum value during sudden braking due to a drop in line oil pressure.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The purpose is to provide an engine control method for a vehicle equipped with a continuously variable transmission that ensures that the gear ratio of the continuously variable transmission reaches its maximum value even when the vehicle is suddenly braking. .

In order to achieve such an object, the gist of the present invention is to provide a vehicle equipped with a continuously variable transmission that continuously changes the speed of the engine and transmits the rotation to the driving wheels. An engine control method for controlling an engine, comprising: (a) detecting a sudden braking state of a vehicle; and (bl) when a sudden braking state of a vehicle is detected, increasing the output of the engine. and an advance angle correction step for correcting the ignition timing.

Operation and Effects of the Invention According to this method, when a sudden braking state of the vehicle is detected, the ignition timing of the engine is corrected to the side that increases the output of the engine, so that the rotational speed of the engine is increased.
The hydraulic pump driven by the engine outputs a sufficient amount of hydraulic oil at a sufficient discharge pressure. As a result, when the gear ratio of the continuously variable transmission is to be changed to the maximum value during sudden braking, the drop in line oil pressure is eliminated and the gear ratio is quickly changed to the maximum value.

Here, in the advance angle correction step, the advance angle is preferably corrected by a predetermined constant value.

In the advance angle correction step, the deceleration of the vehicle, the vehicle speed, the gear ratio of the continuously variable transmission, the target input shaft rotational speed of the continuously variable transmission, and the actual input are preferably determined from a predetermined relationship. A correction value for the advance angle is determined based on at least one of the differences with the shaft rotational speed.

EXAMPLE Hereinafter, an example of a control device for a continuously variable transmission for a vehicle to which the present invention is applied will be explained in detail.

In FIG. 1, a crankshaft 12 of an engine 10 is connected to an input shaft 18 of a belt type continuously variable transmission 16 via a clutch 14.
The output shaft 2 of the belt type continuously variable transmission 16
0 is connected to the drive wheels of the vehicle via a forward/reverse switching device, an auxiliary transmission, a differential gear device, etc. (not shown). Thereby, the rotational force of the engine 10 is transmitted to the drive wheels.

The input shaft 18 and output shaft 20 of the belt type continuously variable transmission 16 are provided with variable pulleys 22 and 24 whose effective diameters are variable, and a transmission belt 26 is wound between the variable pulleys 22 and 24. There is. The variable pulleys 22 and 24 are fixed rotating bodies 28 and 30 fixed to the input shaft 18 and the output shaft 20, and fixed rotating bodies 28 and 30 fixed to the input shaft 18 and the output shaft 20
The movable rotating bodies 32 and 34 are respectively provided to be movable in the axial direction and non-rotatable about the axis.

By changing the thrust applied to the movable rotors 32 and 34 from the hydraulic cylinders 36 and 38, grooves are formed between the fixed rotors 28 and 30 and the movable rotors 32 and 34, respectively. The width, that is, the diameter of the belt can be changed.

The hydraulic oil collected in the oil tank 40 is pumped by an oil pump 41 rotationally driven by the engine 10, and the pressure is regulated to line oil pressure by a pressure regulating valve 42 controlled by a controller 48, which will be described later. This line hydraulic pressure is applied to the secondary side hydraulic cylinder 38 which applies a semi-noise to the secondary side variable pulley 24.
It is directly supplied via the line oil passage 44. usually,
The line oil pressure is determined by the engine 10 from the relational expression determined in advance.
The output torque T, the gear ratio r of the belt type continuously variable transmission 16
(=rotational speed N of the input shaft 18, 7/rotational speed N of the output shaft 20. The tension is maintained at a necessary and sufficient value to prevent the occurrence of

The flow rate control valve 46 is a switching valve controlled by a controller 48, which will be described later, and supplies the hydraulic oil in the line oil passage 44 to the primary side hydraulic cylinder 36 that applies thrust to the primary side variable pulley 22. The gear ratio T is decreased by using the hydraulic cylinder 36, or the hydraulic oil in the hydraulic cylinder 36 is discharged to the drain to increase the gear ratio T.

The intake pipe of the engine 10 is provided with a throttle valve 51 that controls v and N of the fuel mixture by being driven by an accelerator pedal 50, and a throttle sensor that detects the opening degree θ of the throttle valve 51. 52 are provided. The brake pedal 54 is provided with a brake switch 55 for detecting the brake operation. Further, a distributor 57 that distributes an ignition signal to the engine 10 receives a command from a controller 48 (to be described later) to determine when the ignition is activated. An ignition timing adjustment device 59 is provided for correcting l1) (advance amount).

The engine 10 is provided with a water temperature sensor 56 for detecting the temperature of the cooling water. Near the fixed rotating body 28 on the primary side and the fixed rotating body 30 on the secondary side of the continuously variable transmission 16, there are a first rotation sensor 58 and a second rotation sensor 58 for detecting the rotational speed of the input shaft 18 and the output shaft 20. A rotation sensor 60 is provided.

A shift sensor 64 for detecting the operating position of the shift lever 62 is provided in the vicinity of the seat.

As shown in FIG. 2, the controller 48 includes a CPU 66
, ROM6B, RAM70, interface 72, A/
It is a so-called microcomputer equipped with a D converter 74 and a D/A converter 76, and the input shaft rotation signal and the output shaft output from the first rotation sensor 58 and the second rotation sensor 60 according to a program stored in advance in the ROM 68. Inputs include a rotation signal, a shift position signal output from the shift sensor 64, a water temperature signal output from the water temperature sensor 56, a throttle valve opening signal output from the throttle sensor 52, and a brake operation signal output from the brake switch 55. The signal is processed and a drive signal is output to the pressure regulating valve 42, flow rate control valve 46, ignition timing adjustment device 59, etc. For example, the controller 48 may control the engine 1
The target input shaft rotational speed N1,' of the continuously variable transmission 16 is determined based on the throttle valve opening θ and the vehicle speed from a predetermined relationship such that the fuel consumption rate 0 operates along the minimum fuel consumption rate curve. The flow rate control valve 46 is operated so that the target input shaft rotational speed N i n and the actual input shaft rotational speed N i n match.

The main part of the control operation of the controller 48 will be explained below with reference to FIG. The flowchart in FIG. 3 is for controlling the output of the engine 10 in order to ensure that the gear ratio of the continuously variable transmission 16 reaches its maximum value when the vehicle is suddenly braked.

First, in a step not shown, the input signals are read, and the input shaft rotational speed Ni,
(=edge 2 rotation speed N,), output shaft rotation speed N. uL
, vehicle speed ■, gear ratio γ, vehicle deceleration α, etc. are calculated. In the following step SO, a flag F indicating engine control is set.
It is determined whether the content of is rlJ. During normal driving, the content of flag F is not "1", that is, engine control during sudden braking has not started, so step Sl
The following will be executed: In these steps S1, S2, and S3, whether the brake switch 55 is on or not,
It is determined whether the vehicle speed V is less than or equal to a predetermined value vA, and whether or not the deceleration α of the vehicle is greater than or equal to a predetermined value α4. In other words, a sudden braking state is determined in which the vehicle speed decreases as the brake is operated and the deceleration α of the vehicle is large. The predetermined values vA and α are suitable for detecting sudden braking of the vehicle in which the drive wheels come to a stop before the gear ratio T of the continuously variable transmission 16 reaches the maximum value γsex. A value is selected.

If any of the judgments in steps Sl, S2, and S3 is negative, step S6 is executed and the content of the flag F is reset to "0", and then step Sl
1, the ignition timing adjustment device 59 is controlled so that the engine 10 is ignited at the normal ignition timing. but,
If the judgments in steps Sl, S2, and S3 are all affirmative, the drive wheels may stop before reaching the gear ratio T71)<maximum value 1)1) of the continuously variable transmission 16. Since the vehicle is in a sudden braking state, first step S is performed.
4, the gear ratio T of the continuously variable transmission 16 is the maximum value γmmx
It is determined whether or not the target has been reached. If the gear ratio T has been reached, there is no need to change the gear ratio T any further, and the steps from step 86 onwards are executed; however, if the gear ratio T has not been reached, the content of the flag F is set to "1" in step S5. At the same time, the actual deceleration α is read in step S7. Then, in step S8, the actual deceleration α is determined from the pre-stored relationship shown in FIG.
Ignition timing is determined based on This ignition timing is obtained by adding an advance correction value to the normal basic ignition timing to increase the engine output during sudden braking, and the ignition timing adjustment device 59 controls the ignition timing in step S8 so that this ignition timing is obtained. be done. The relationship shown in FIG. 4 has been experimentally determined in advance so that the line oil pressure can be appropriately increased when it is determined that the vehicle is suddenly braking.

Also, as mentioned above, the relationship shown in Figure 4 is a correction made to the normal ignition timing, so it is necessary to use that relationship to determine the ignition timing and add the advance angle correction value to the normal ignition timing. This is essentially the same as correcting it. In this application example, steps S1, S2, and S3 are included in the sudden braking state detection step.
Further, steps S7 and S8 correspond to the advance angle correction step.

If it is determined in step SO that the content of flag F is [1], it is determined in step S9 whether the brake switch 55 is on, and in the following step SIO it is determined whether the vehicle speed V is zero. It is determined whether or not. If the brake switch 55 is off, it is considered that the sudden braking operation has been completed, so step 86 is performed.
The following steps are executed, and if the vehicle speed (2) is zero, there is no need to increase the amount of fuel, so steps 86 and subsequent steps are executed. However, if the brake switch 55 is on and the vehicle speed V is not zero, it is considered that the sudden braking state is still continuing, so the steps from step 84 onwards are executed.

As described above, according to the present embodiment, when the vehicle is suddenly braked to the extent that the drive wheels are stopped before the gear ratio T of the continuously variable transmission 16 reaches the maximum value γsix, the controller 48 Since the ignition timing adjustment device 59 is operated so that the engine 10 is ignited at the ignition timing increased by the advance angle correction value corresponding to the deceleration α of the vehicle,
The rotation of the engine IO is increased by a predetermined amount, the amount of oil discharged by the oil pump 41 is increased, and the discharge pressure is maintained high. As a result, the line oil pressure is increased, so that the gear ratio T of the continuously variable transmission 16 can easily reach the maximum value T max even during sudden braking. Therefore, when the vehicle restarts, sufficient driving force is obtained, and at the same time, the gear ratio T of the continuously variable transmission 16 temporarily reaches the maximum value T. The unpleasant shock caused by being changed to 1X is also eliminated.

That is, in a vehicle equipped with the continuously variable transmission 16, the rotational speed Ni of the input shaft 18 of the continuously variable transmission 16 decreases along the solid line in FIG. 5 during normal braking, but during sudden braking the driving wheels decrease. Since it stops early, it is unavoidable that the gear ratio decreases along the broken line in FIG. There were times when the ratio T was maintained until the vehicle was restarted. However, according to the engine control device of this embodiment, the advance correction of the ignition timing is performed during sudden braking, so as shown by the broken line in the time chart of FIG. 6, the advance correction shown by the solid line is not performed. Compared to the case, input shaft 1
At the same time as the rotational speed N i n of 8 increases, the gear ratio T
Changes in this are suitably promoted.

Next, another application example of the present invention will be explained.

As shown in FIG. 7, steps S7 and S8 in FIG.
Instead, steps S7° and S8° may be provided. That is, in step S7'', the target input shaft rotational speed N, 71 and the actual input shaft rotational speed N i n of the gear ratio control are read, and their control deviation Δ
N i n is calculated. Then, in step S8', the ignition timing is calculated based on the control deviation ΔN i from the pre-stored relationship shown in FIG. 8.

Also at this ignition timing, an advance angle correction value is added in relation to the control deviation ΔN in .

Although one application example of the present invention has been described below, the present invention can also be applied to other embodiments.

For example, in the application example described above, the ignition timing during sudden braking was calculated based on the deceleration α and the control deviation ΔN i n , but it is calculated based on the vehicle speed V or the gear ratio γ of the continuously variable transmission 16. Alternatively, it may be calculated based on two or more of the following parameters: deceleration α, control deviation ΔN i n , vehicle speed V, and gear ratio γ. Further, even if a predetermined constant value is used as the ignition timing advance angle correction value, a certain effect can be obtained.

Further, in the above-mentioned embodiment, a vehicle is described in which the ignition timing of the engine 10 is determined by the output timing of the high voltage distributed from the distributor 57 to the spark plug, but for example, in a diesel engine, etc. The present invention can also be applied to a vehicle in which the ignition timing of the engine is determined by the fuel injection timing. In this case, instead of the ignition timing control device, the controller 48 controls, for example, a control valve for correcting the position of the timer piston of the fuel injection pump.

In addition, the above-mentioned Figures 4 and 8 show the relationship after the correction for sudden braking is added to the normal ignition timing, so by using those relationships, it is possible to determine the optimum timing for sudden braking. The ignition timing with the advance angle correction is determined, but after determining the advance angle correction value using the relationship representing the advance angle correction value that changes in relation to the deceleration α and the control deviation ΔN, 7. The ignition timing during sudden braking may be determined by adding the advance angle correction value to the normal ignition timing.

Note that the above-described example is only one application example of the present invention, and the present invention is also applicable to other embodiments.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a continuously variable transmission for a vehicle, which is an application example of the present invention. FIG. 2 is a block diagram illustrating a control device for the continuously variable transmission shown in FIG. 1. FIG. 3 is a flowchart showing the operation of the control device of FIG. 2. FIG. 4 is a diagram showing the relationships used in the flowchart of FIG. 3. FIG. 5 is a diagram illustrating a state in which the input shaft rotational speed decreases due to braking of the vehicle in the embodiment of FIG. 1. FIG. 6 is a time chart showing the operation of the embodiment of FIG. 1 in comparison with the conventional case. 7th
The figure is a diagram showing a main part of another application example of the present invention. 8th
The figure is a diagram showing the relationships used in the example of FIG. 7. lO: Engine 16: Belt-type continuously variable transmission Applicant: Toyota Motor Corporation μJLKE Figure 2 Figure 3 Figure 4 Figure S Figure 6 → SDA government destruction

Claims (3)

[Claims] (1) An engine control method for controlling fuel supplied to the engine in a vehicle equipped with a continuously variable transmission that continuously changes the speed of the engine and transmits it to the drive wheels, the method comprising: The present invention includes the steps of: detecting a braking state; and, when a sudden braking state of the vehicle is detected, an advance angle correcting step of correcting the ignition timing of the engine in a direction to increase the output of the engine. A method for controlling an engine of a vehicle equipped with a stepped transmission. (2) The engine control method for a vehicle equipped with a continuously variable transmission according to claim 1, wherein the advance angle correction step corrects the advance angle by a predetermined constant value. (3) In the advance angle correction step, based on a predetermined relationship,
A correction value for the advance angle based on at least one of the deceleration of the vehicle, the vehicle speed, the gear ratio of the continuously variable transmission, and the difference between the target input shaft rotation speed and the actual input shaft rotation speed of the continuously variable transmission. An engine control method for a vehicle equipped with a continuously variable transmission according to claim 1, which determines the following: