JPH04303144A - Device and method for reducing friction for vehicle equipped with antilock brake system - Google Patents

Abstract

PURPOSE:To achieve an ABS function sufficiently in a simple structure. CONSTITUTION:When an ABS operation detection circuit 41 an antilock brake system operation signal outputted from an antilock brake system control unit 14 to determine that the antilock brake system has operated, an air condition switch detection means 43 puts an air compressor magnet clutch 36a off to stop driving an air conditioner, and a fuel injection pulse width computation means 42 computes a fuel injection pulse width based on output values of sensors 32-35. Fuel is then supplied from an injector 39 to an applicable cylinder based on the fuel injection pulse width. As a result, loads on an engine from auxiliary devices are reduced for the operation of the ABS, and the engine rotates automatically to offset a friction of a drive system, thereby a originally provided function of the ABS can be achieved sufficiently.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction reduction device and method for a vehicle equipped with an anti-lock brake system, which reduces the friction applied from the drive system to the wheels when the anti-lock brake system is in operation.

0002

[Prior Art] As is well known, an anti-lock brake system (hereinafter abbreviated as "ABS") prevents wheels from locking or skidding due to locking when the brakes are applied, thereby ensuring directional stability and steering performance. At the same time, this system aims to shorten stopping distance by maximizing braking force. Specifically, when ABS is activated, brake hydraulic pressure is repeatedly increased/decreased to avoid wheel locking and increase wheel speed. Alternatively, the deceleration is controlled to a desired value (determined by the vehicle speed).

For example, when the brakes are operated on a road with a low μ (friction coefficient), if at least one wheel is likely to lock, the ABS attempts to reduce the brake oil pressure and increase the wheel speed, but the vehicle If the friction in the drive system (including engine braking) is large, it will not be possible to restore the desired wheel speed, and the wheels will likely become locked.

FIG. 8 shows the relationship between (a) wheel speed and (b) brake oil pressure when ABS is activated on a low μ road.

[0005] In this ABS, when wheel slip determined from the relationship between wheel speed and vehicle body speed (wheel speed on the verge of starting braking) is detected, this wheel speed becomes a predetermined slip ratio λ with respect to the vehicle body speed. Control the brake oil pressure as follows.

[0006] The above-mentioned slip ratio λ is determined by λ={(vehicle speed−wheel speed)/vehicle speed}×100.

(1) When the ABS operates normally, the wheel speed quickly increases as the brake oil pressure decreases as shown by the solid line, and falls within a predetermined slip ratio λ with respect to the vehicle speed shown by the thick line.

(2) On the other hand, when the engine brake, which causes friction in the drive system, is relatively large, the wheel return speed does not increase immediately even if the brake oil pressure is lowered, resulting in a delay in return, resulting in poor ABS controllability, as shown by the dashed line. becomes worse.

(3) Furthermore, if the engine brake described above becomes excessive, the wheel speed will not increase even if the ABS is activated, and the wheels will eventually lock (stop), and no matter how much the brake oil pressure is reduced, the wheel speed will not increase. will not recover.

[0010] In order to effectively operate ABS, it is necessary to control the wheel speed so that it is optimal relative to the vehicle speed, but as mentioned in (2) and (3) above,
If the recovery of wheel speed is delayed or the wheels lock, directional stability, steering performance, shortening of stopping distance, etc. will be significantly impaired.

As a measure to reduce the friction factor of the drive system, (1) as disclosed in Japanese Patent Laid-Open No. 64-1651, when the ABS is activated, the automatic transmission engages the engine brake. (2) As disclosed in Japanese Unexamined Patent Publication No. 1-262230, when the ABS is activated, the automatic transmission (3) or when ABS is activated as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-262230;
Some types open the throttle valve to increase the amount of air supplied to the cylinders, weakening the effect of engine braking.

0012

[Problem to be solved by the invention] However, as mentioned above (1)
, (2), when the ABS is activated, the friction in the drive system is completely eliminated even if the engine brake engagement element is released or the automatic transmission is switched to a mode in which the engine brake does not work. However, due to the influence of the residual friction, it becomes difficult to fully utilize the ABS function. Further, since the method automatically releases the engine brake engagement element or automatically switches the gear change mode of the automatic transmission, it cannot be applied to a vehicle equipped with a manual transmission.

On the other hand, in the technology described in (3), which opens the throttle valve when the ABS is activated, it merely increases the amount of air supplied to the cylinders and weakens the engine brake. Since the friction in the system has not been actively removed, AB
Not only is it difficult to make full use of the S function, but actuators to automatically open and close the throttle valve must be placed in front of the throttle, which complicates the structure and makes manufacturing, assembly, and maintenance difficult. There is a problem that inspections become complicated.

The present invention has been made in view of the above circumstances, and provides a vehicle with an anti-lock brake system that has a simple structure, is easy to manufacture and assemble, and is easy to maintain and inspect, and can fully utilize the ABS function. It is an object of the present invention to provide a friction reduction device and a friction reduction method.

[0015]

[Means for Solving the Problems] (1) In order to achieve the above object, a friction reduction device for a vehicle with an anti-lock brake system according to the present invention has an output from an anti-lock brake system control means M1 as shown in FIG. an ABS operation detection means M2 that receives an anti-lock brake system activation signal to detect the anti-lock brake system activation state; and an auxiliary device that stops the operation of auxiliary devices M3 attached to the engine when the anti-lock brake system is activated. and fuel injection pulse width calculation means for calculating a fuel injection pulse width that offsets at least the friction of the drive system based on the engine state detected by the engine operating state detection means M5 when the anti-lock brake system is in the operating state. M6, and fuel supply means M7 that supplies fuel to the corresponding cylinder based on the fuel injection pulse width.

(2) In order to achieve the above object, the method for reducing friction in a vehicle with an anti-lock brake system according to the present invention incorporates an anti-lock brake system activation signal output from an anti-lock brake system control means to control the anti-lock brake system. It detects the operating state and stops the operation of auxiliary equipment attached to the engine when the anti-lock brake system is operating.
Based on the engine state detected by the engine operating state detection means, a fuel injection pulse width that at least offsets friction in the drive system is calculated, and then fuel is supplied to the corresponding cylinder based on the fuel injection pulse width. .

[0017]

[Function] (1) In the friction reduction device for a vehicle equipped with an anti-lock brake system having the above configuration, the ABS
When the operation detection means M2 receives the anti-lock brake system operation signal output from the anti-lock brake system control means M1 and determines that the anti-lock brake system has been activated, the auxiliary equipment operation stop means M4 performs the following steps:
The operation of the auxiliary equipment M3 attached to the engine is stopped, and the fuel injection pulse width calculation means M6 calculates a fuel injection pulse width that at least offsets the friction of the drive system based on the engine state detected by the engine operating state detection means M5. Calculate.

Then, fuel is supplied from the fuel supply means M7 to the corresponding cylinder based on the fuel injection pulse width.

As a result, ABS operation requires sufficient use of the original ABS function in order to reduce the load on the engine from auxiliary equipment, and also to allow the engine to rotate spontaneously to cancel out the friction in the drive system. It can be demonstrated.

(2) In the friction reduction method for a vehicle equipped with an anti-lock brake system having the above configuration, when it is determined that the anti-lock brake system has been activated based on the anti-lock brake system activation signal output from the anti-lock brake system control means, The operation of auxiliary machinery attached to the engine is stopped, and a fuel injection pulse width that at least offsets the friction of the drive system is calculated based on the engine state detected by the engine operating state detection means.

Then, fuel is supplied to the corresponding cylinder based on the fuel injection pulse width.

As a result, ABS operation requires sufficient use of the original ABS function in order to reduce the load on the engine from auxiliary equipment, and to rotate the engine spontaneously to offset the friction in the drive system. It can be demonstrated.

[0023]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

2 to 7 show an embodiment of the present invention, FIG. 2 is a functional block diagram of a friction reduction device, FIG. 3 is a flowchart showing a fuel injection control procedure, and FIG. 4 is a flowchart showing an air conditioner operation control procedure. FIG. 5 is a flowchart showing the alternator operation control procedure, FIG. 6 is an overall schematic diagram of the engine control system and ABS control system, and FIG. 7 is a hydraulic circuit diagram of the hydraulic unit.

(Structure) Reference numeral 1 in FIG. 6 is a drive system of a four-wheel drive vehicle, which is an example of a vehicle, from a transmission 3 connected to an engine 2 mounted on the front side to a front drive shaft 4a, 4b is extended,
A propeller shaft 5 extends rearward, and rear drive shafts 6a, 6b extend from the propeller shaft 5 to both sides via a rear differential gear 7. Wheels 7 are connected.

Furthermore, a brake 8 is attached to each wheel 7, and a wheel cylinder 8a of each brake 8 is communicated with a master cylinder 11 connected to a brake pedal 10 via a brake pipe 9. Furthermore, a hydraulic unit 12 that constitutes an ABS (anti-lock brake system) is interposed in this brake pipe 9.

Further, an excitation coil 13a (see FIG. 7) of a solenoid valve 13 provided in the hydraulic unit 12 and communicating with the wheel cylinder 8a of each brake 8 is connected to the output side of an ABSECU (electronic control unit) 14. ing. Further, a wheel speed sensor 15 for detecting the rotational speed of each wheel 7 is connected to the input side of the ABSECU 14.

The ABSECU 14 calculates the ever-changing wheel slip rate λ based on the wheel speed detected by the wheel speed sensor 15 and the relationship between this wheel speed and the vehicle body speed (the wheel speed just before the start of braking). A control signal is output to each of the solenoid valves 13 to adjust the brake oil pressure transmitted to the wheel cylinder 8a of each brake 8 so that the wheel speed falls within a preset slip ratio range. At the same time, an activation signal is output to the motor relay 16 of the hydraulic unit 12, and the pump motor 17 (FIG. 7
reference). As shown in FIG. 7, the hydraulic unit 12 includes an F valve (valve for preventing pedal reaction force) 21, a check valve 22, a solenoid valve 13, a reservoir 23, an inlet valve 24, a plunger pump 25, and an outlet valve 26. , cam 2
7, a pump motor 17, and an accumulator 28.

On the other hand, reference numeral 31 is an engine control unit (E/GECU), and this E/GECU31
On the input side of the engine, an intake air amount sensor 32 for measuring the intake air amount Qa, which constitutes an engine operating state detection means, a crank angle sensor 33 for detecting the engine rotation speed Ne, and a cooling water temperature Tw as a means for detecting the engine temperature are installed. The water temperature sensor 34 detects the throttle opening Thr, the throttle sensor 35 detects the throttle opening Thr (Thr=0 when the throttle valve is fully closed), and is one of the auxiliary devices connected to the crank pulley 2b of the engine 2 via a belt or the like. Turn on air conditioner 36
/ OFF air conditioner switch 37 is connected, and the ABSECU 14 is connected to the motor relay 1.
A signal line outputting to 6 is connected.

Furthermore, the compressor magnetic clutch 36a of the air conditioner 36 and the field coil 38a of the alternator 38, which is one of the auxiliary equipment, are connected to the output side of the E/GECU 31, and the Injectors 39, which are fuel supply means, are connected to each intake port side of the intake manifold 2a.

As shown in FIG. 2, the above E/GECU3
1, the function of reducing the friction of the drive system during ABS operation is performed by the ABS operation detection circuit 41, the fuel injection pulse width calculation means 42, the air conditioner switch detection circuit 43, the AND circuit 44, and the above-mentioned fuel injection pulse width calculation means. A drive circuit 45 that outputs a drive signal corresponding to the fuel injection pulse width Ti output from 42 to the injector 39, the above AN
When a Hi signal is output from the D circuit 44, the air conditioner 3
a drive circuit 46 that outputs an OFF signal (clutch release) to the air conditioner compressor magnetic clutch 36a of No. 6;
The driving circuit 47 sets the voltage applied to the field coil 38a of the alternator 38 to 0V when the ABS operation detection circuit 41 detects an ABS operation.

Note that the circuit operation of this E/GECU 31 is the same as the program operation described later, so a description thereof will be omitted.

(Function) Next, the function of the embodiment having the above configuration will be explained.

First, the operation of the hydraulic unit 12 will be briefly explained.

When ABS is not activated: When ABS is not activated, the current flowing to the excitation coil 13a of the solenoid valve 13 is OFF (0V), and the hydraulic pressure generated by the master cylinder 11 when the brake pedal 10 is pressed is applied to the F valve. 21
The ball is pushed up and sent to the solenoid valve 13, but since this solenoid valve 13 is in an inactive state,
The signal is transmitted directly to the wheel cylinder 8a of the brake 8, and the brake 8 is activated.

On the other hand, the hydraulic pressure passing through the F valve 21 is
It also reaches the outlet valve 26, but it is sealed with a ball. Further, the accumulator 28 has a strong valve spring force and does not operate under the regular brake hydraulic pressure. Further, the outlet port 13b of the solenoid valve 13 is sealed because the current is off, and the passage to the reservoir 23 is blocked.

When the brake pedal 10 is released to release the brake, the hydraulic pressure in the master cylinder 11 decreases, and the hydraulic pressure in the wheel cylinder 8a pushes up the ball of the check valve 22 and returns to the master cylinder 11 side. At this time, the F valve 21 functions as a check valve to prevent the oil pressure in the wheel cylinder 8a from returning to the master cylinder 11 side, but when the oil pressure in the master cylinder 11 drops to a predetermined pressure, the F valve 21 acts as a check valve to prevent the oil pressure in the wheel cylinder 8a from returning to the master cylinder 11 side. The ball is moved to the left by the biasing force, and the slight residual pressure in the wheel cylinder 8a caused by the check valve 22 passes through the solenoid valve 13 and is transferred from the F valve 21 to the master cylinder 1.
Released to 1.

When the ABS is activated: The ABSECU 14 calculates the slip ratio λ, and if this slip ratio λ is lower than a predetermined value, that is, when a certain wheel 7 is about to lock, such as during braking, the ABSECU 14 calculates the solenoid valve 13. A depressurizing current is applied to the excitation coil 13a, and the inlet port 13c of the solenoid valve 13 is closed and the outlet port 13b is opened. Therefore, the hydraulic pressure of the wheel cylinder 8a is sent to the reservoir 23 through the outlet port 13b.

At the same time, a drive signal is output from the ABSECU 14 to the motor relay 16, and this motor relay 1
6 is turned on, and the pump motor 17 rotates. Then, the plunger pump 25 is actuated via the cam 27 connected to the pump motor 17, and the brake hydraulic pressure sent to the reservoir 23 passes through the inlet valve 24, is increased in pressure by the plunger pump 25, and is applied to the outlet valve 26. The water is stored in the accumulator 28 through the following steps.

At this time, the brake hydraulic pressure increased by the plunger pump 25 closes the ball of the F valve 21 and is not transmitted to the master cylinder 11. Further, since the brake oil pressure in the wheel cylinder 8a is reduced, the check valve 22 is closed due to the pressure difference, and is isolated from the master cylinder 11.

In this way, the brake hydraulic pressure of the wheel cylinder 8a is reduced in a state completely separated from the master cylinder 11, and the brake hydraulic pressure of the wheel cylinder 8a is reduced while preventing kickback to the brake pedal 10. Control the pressure reduction. Next, the fuel injection control procedure will be explained according to the flowchart of FIG.

First, step (hereinafter abbreviated as "S") 10
1, in order to detect the engine operating state, the engine rotation speed Ne, intake air amount Qa, cooling water temperature Tw, and throttle are determined based on the output signals of the crank angle sensor 33, intake air amount sensor 32, water temperature sensor 34, and throttle sensor 35. Calculate the opening Thr.

Next, in S102, a drive signal output from the ABSECU 14 to the motor relay 16 of the hydraulic unit 12 is input to determine whether the ABS is in operation. If it is determined that the ABS is not activated, the process proceeds to S103, and if it is determined that the ABS is activated, the process proceeds to S106.

When the process advances to S103, the engine speed Ne
, Preset fuel cut lower limit rotation speed during deceleration Ne C
UT (for example, 1500 to 2000 rpm), and if Ne≧NeCUT, proceed to S104, and set Ne
If <Ne CUT, proceed to S106 to restart fuel injection.
Proceed to.

Then, when the process proceeds to S104, it is determined from the throttle opening Thr whether the throttle valve is fully closed (Thr=0), and if Thr=0, it is determined that the vehicle is decelerating and the process proceeds to S1.
At 05, the fuel injection pulse width Ti is set to 0 (fuel cut) and the routine exits.

On the other hand, it is determined in S102 that ABS is activated;
If it is determined in S103 that Ne < Ne CUT, or that Thr≠0 (throttle valve open) is determined in S104 and the process proceeds to S106, the engine operating condition Ne is
, Qa, Tw, etc., the fuel injection pulse width T
i is calculated based on the following formula, a drive pulse corresponding to the fuel injection pulse width Ti is outputted to the injector 39 of the corresponding cylinder at a predetermined timing, and the routine is exited.
In reality, various other correction terms are taken into consideration, but they are omitted.)

Ti=K(Qa/Ne)×(1+f(Tw))
K: Constant f(T) based on injector characteristics, air-fuel ratio, etc.
w ): water temperature correction coefficient, (f(Tw) > 0 in cold state, increase after warming up f(Tw) =
0) Since the above fuel injection pulse width Ti is set based on the intake air amount Qa and the engine speed Ne, this value is corrected using various correction terms, so when ABS is activated, for example, the throttle valve is fully closed. In this case, the fuel injection pulse width Ti is set to a value that offsets the friction of the drive system including the engine brake.

Next, the operation control procedure of the air conditioner 36 is shown in FIG.
This will be explained according to the flowchart.

First, in S201, it is determined whether or not the air conditioner switch 37 is ON. If it is ON, the process advances to S202, and the air conditioner switch 37 is turned ON.
In the case of F, the process advances to S204.

When the process advances to S202, the drive signal output from the ABSECU 14 to the motor relay 16 of the hydraulic unit 12 is received, and it is determined whether the ABS is in operation. If the ABS is not activated, the process proceeds to S203, and if the ABS is activated, the process proceeds to S203. Proceed to S204.

Proceeding to S203, the compressor magnetic clutch 36a of the air conditioner 36 is turned on, and the engine 2
The compressor connected to the crank pulley 2b via the belt is driven, and the routine exits.

Meanwhile, in S201, the air conditioner switch is turned off.
, or it is determined that ABS is activated in S202 and the ABS is activated in S20.
When proceeding to step 4, the compressor magnetic clutch 36a of the air conditioner 36 is turned off, the drive of the compressor is stopped, and the routine exits.

Next, the operating procedure of the alternator 38 is shown in FIG.
This will be explained according to the flowchart.

First, in S301, a drive signal output from the ABSECU 14 to the motor relay 16 of the hydraulic unit 12 is input to determine whether the ABS is in operation. If the ABS is not in operation, the field coil of the alternator 38 is activated in S302. A voltage is applied to 38a to drive the load and the routine exits. In addition, in the case of ABS operation, S3
The program proceeds to step 03, where the voltage applied to the field coil 38a of the alternator 38 is set to 0V, and no-load driving is performed, and the routine exits.

In this manner, when the ABS is activated, the load of the air conditioner 36 and alternator 38 on the engine 2 is cut off, and the engine is driven with an injection amount that offsets the friction of the drive system including the engine brake. Therefore, the wheel return speed can always have characteristics close to the normal state shown by the solid line in FIG. 8, and therefore, the functions of the ABS can be effectively exhibited.

Note that the present invention is not limited to the above-mentioned embodiments. For example, the auxiliary equipment is not limited to air conditioners and alternators. Furthermore, a magnetic clutch may be provided on the crank pulley and the magnetic clutch may be released when ABS is activated. By doing so, all auxiliary equipment may be stopped at once.

[0057]

As explained above, according to the present invention, the following effects can be achieved.

(1) As described in claim 1, ABS operation detection means receives an antilock brake system operation signal output from the antilock brake system control means and detects the antilock brake system operation state; An auxiliary equipment operation stop means for stopping the operation of auxiliary equipment attached to the engine when the anti-lock brake system is in an operating state, and an engine state detected by an engine operating state detection means when the anti-lock brake system is in an operating state. By including a fuel injection pulse width calculation means for calculating a fuel injection pulse width that offsets at least the friction of the drive system, and a fuel supply means for supplying fuel to the corresponding cylinder based on the fuel injection pulse width, the The friction of the drive system transmitted to the wheels is actively offset, allowing the ABS function to be fully utilized.

[0059] Furthermore, since it does not require mechanical parts like the conventional throttle control system, the structure is simple, and manufacturing, assembly, and maintenance and inspection are easy. Furthermore, the fail-safe mechanism in this system is simplified. be able to. In addition, automatic transmission vehicles,
It can be used in any manual transmission vehicle.

(2) As stated in claim 2,
The anti-lock brake system operation signal output from the anti-lock brake system control means is received to detect the operation state of the anti-lock brake system, and when the anti-lock brake system is in the operation state, the operation of auxiliary equipment attached to the engine is stopped. The fuel injection pulse width that offsets at least the friction of the drive system is calculated based on the engine state detected by the engine operating state detection means, and then fuel is supplied to the corresponding cylinder based on the fuel injection pulse width. The friction of the drive system transmitted to the wheels when ABS is activated is actively offset, allowing the ABS function to be fully utilized.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a friction reduction device according to claim 1.

[Fig. 2] Fig. 2 to Fig. 7 show an embodiment of the present invention, and Fig. 2 is a functional block diagram of a friction reduction device.

[Figure 3] Flowchart showing fuel injection control procedure

[Figure 4] Flowchart showing the operation control procedure of the air conditioner

[Figure 5] Flowchart showing the alternator operation control procedure

[Figure 6] Overall schematic diagram of engine control system and ABS control system

[
Figure 7: Hydraulic circuit diagram of hydraulic unit

[Figure 8]A
Time chart showing the relationship between wheel speed and brake oil pressure when BS is activated

[Explanation of symbols]

M1...Anti-lock brake system control means M2...A
BS operation detection means M3...Auxiliary machines M4...Auxiliary machines operation stop means M5...Engine operating state detection means M6...Fuel injection pulse width calculation means M7...Fuel supply means

Claims (2)

[Claims] Claim 1: ABS operation detection means for receiving an antilock brake system operation signal output from the antilock brake system control means and detecting the antilock brake system operation state; auxiliary equipment operation stopping means for stopping the operation of auxiliary equipment that is activated, and a fuel injection pulse width that at least offsets friction in the drive system based on the engine state detected by the engine operating state detection means when the anti-lock brake system is in the operating state. A friction reduction device for a vehicle with an anti-lock brake system, comprising: a fuel injection pulse width calculation means for calculating the fuel injection pulse width; and a fuel supply means for supplying fuel to a corresponding cylinder based on the fuel injection pulse width. [Claim 2] The anti-lock brake system operation signal output from the anti-lock brake system control means is received to detect the operation state of the anti-lock brake system, and when the anti-lock brake system is in the operation state, the operation of the auxiliary equipment attached to the engine is controlled. At the same time as stopping the operation, a fuel injection pulse width that offsets at least the friction of the drive system is calculated based on the engine state detected by the engine operating state detection means, and then fuel is supplied to the corresponding cylinder based on the fuel injection pulse width. A method for reducing friction in a vehicle equipped with an anti-lock brake system.