JPS6341781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antiskid device for a vehicle that prevents wheels from locking.

Conventionally, this type of anti-skid device detects the rotational speed of a wheel using a wheel speed sensor, and determines whether the deceleration of the wheel exceeds a predetermined deceleration reference value.
Alternatively, when the slip rate of the wheel exceeds a predetermined value, the brake pressure supplied to the brake device of the wheel is reduced so that the deceleration of the wheel becomes smaller than the deceleration reference value, or the slip rate reaches the predetermined value. Even in these cases, when the wheels start to accelerate, the brake pressure is increased.

However, in this conventional anti-skid device, when the deceleration of the wheels exceeds a predetermined deceleration reference value, the brake pressure is reduced regardless of the slip ratio, so the rotational speed of the wheels suddenly changes transiently depending on the road surface conditions. Even when the deceleration exceeded the deceleration reference value, there was a risk that the brake pressure would decrease and the braking force would be insufficient. Also, when the slip rate of the wheels exceeds a predetermined reference value, the brake pressure is released, but since the brake pressure is released at a constant rate of decrease regardless of the magnitude of the wheel deceleration, when the wheel deceleration is large, There is a drawback that the speed at which the brake pressure decreases is insufficient, resulting in a high wheel slip rate, and when the deceleration of the wheels is small, the rate at which the brake pressure decreases becomes excessive, causing the brake pressure to drop more than necessary.

Furthermore, Japanese Patent Application Laid-open No. 49-132468 describes a system that makes the rate of decrease and rate of increase in brake pressure variable depending on the magnitude of the friction coefficient μ between the road surface and the wheels, but the wheel speed attenuation Alternatively, the recovery is not only due to the friction coefficient μ. That is,
Attenuation or recovery of wheel speed also varies greatly depending on the brake torque at that time. Therefore, as shown in the prior art, if the friction coefficient μ is used as a parameter to vary the rate of decrease and increase in brake pressure, even if the friction coefficient μ is the same,
For example, even if the brake torque is too high and the wheels will actually slip significantly unless the rate of decrease in brake pressure is increased, the rate of decrease in brake pressure is constant, so the decrease in brake pressure is insufficient, and the wheels will slip significantly. The vehicle slips and becomes unstable. In addition, even if the brake torque is small and there is no need to increase the rate of decrease in brake pressure, in conventional systems, the rate of decrease in brake pressure is constant, so the decrease in brake pressure is excessive and the braking distance is extended. Put it away. A similar drawback occurs when the brake pressure increases.

The present invention has been made in view of the above drawbacks, and includes a wheel speed calculator that generates a wheel speed signal that is proportional to the rotational speed of the wheel, and a wheel speed calculator that differentiates the wheel speed signal and generates a signal that is proportional to the acceleration/deceleration of the wheel. an acceleration/deceleration calculator that generates an acceleration/deceleration signal; a slip rate comparator that obtains a slip rate signal from the wheel speed signal and a vehicle body speed signal proportional to the vehicle body speed; and a brake device for the wheel when the slip rate signal is generated. and a pressure control valve for controlling brake pressure supplied to the vehicle, the anti-skid device for a vehicle is configured to vary the rate of increase and decrease of the brake pressure based on a predetermined parameter, the parameter being the acceleration/deceleration signal, and the brake pressure being supplied to the vehicle. A switching device is provided that variably switches the rate of increase and decrease of the brake pressure according to the magnitude of the acceleration/deceleration signal when the slip rate is equal to or higher than a predetermined value, thereby optimally controlling the brake pressure of the wheels. An object of the present invention is to provide an anti-skid device for a vehicle.

That is, the rate of decrease and rate of increase in brake pressure is made variable by the acceleration/deceleration signal of the wheels, which is determined comprehensively by the coefficient of friction μ between the road surface and the wheels, the brake torque, and the like.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing a block diagram of a control circuit, a wheel speed sensor 1 is attached to a wheel or a propeller shaft that rotates with the wheel, and generates a pulse signal proportional to the rotational speed of the wheel. This pulse signal is transmitted to the vehicle record speed calculator 2 and converted into a wheel speed signal V proportional to the rotational speed of the wheels.

This wheel speed signal V is transmitted to the acceleration/deceleration calculator 3. The acceleration/deceleration calculator 3 differentiates the wheel speed signal V and outputs an acceleration/deceleration signal V≦ proportional to the acceleration/deceleration of the wheel. The sign of this acceleration/deceleration signal V〓 is + when the wheel is in an acceleration state, and - when the wheel is in a deceleration state.

A subtracter 4 outputs an acceleration/deceleration signal V〓 and a constant value V〓 corresponding to a predetermined acceleration. and a constant value V〓. Outputs the value (V〓.−V〓) obtained by subtracting the acceleration/deceleration signal V〓 from. Therefore, the output signal of subtractor 4 (V〓.−V〓)
becomes a larger value as the acceleration signal of the acceleration/deceleration calculator 3 decreases and the deceleration signal increases.

The vehicle speed calculator 5 receives the wheel speed signal V from the wheel speed signal calculator 2 and the vehicle deceleration signal -α from the detector 51 that detects the deceleration of the vehicle.
Under normal conditions, the same value as the wheel speed signal V is output, and when the rate of decrease in the wheel speed signal V exceeds a predetermined value, the vehicle body speed signal E decreases at a rate of decrease corresponding to the deceleration of the vehicle body.
Output.

This vehicle speed signal E is transmitted to the attenuator 6,
It is reduced to a certain percentage (η), for example 95%.

The comparator 7 receives the wheel speed signal V from the wheel speed calculator 2 and the output signal η·E from the attenuator 7,
When the wheel speed signal V becomes less than a predetermined ratio η·E of the vehicle speed signal E, a slip rate control signal S is generated, that is, the output signal of the comparator 7 becomes H.

The switch 8 receives the output signal (V〓) from the subtracter 4.
-V〓), and when the output signal of the comparator 7, that is, the slip rate control signal S, is H, a signal (V〓.-V〓) is transmitted to the amplifier 9.

The amplifier 9 outputs an electric voltage I proportional to the output signal (V〓.-V〓) of the subtracter 4 transmitted via the switch 8.
is supplied to a solenoid 10 of a pressure control valve to be described later.

Next, a brake pressure control device including a pressure control valve will be explained with reference to FIG.

The pressure control valve, indicated generally at 20, has a supply port 2
1, equipped with a delivery port 22 and a discharge port 23, and a supply port 2
1 is connected to a master cylinder 25 via a pipe 24, the outlet 22 is connected to a wheel cylinder 28 of a wheel brake device 27 via a pipe 26, and the discharge port 23 is connected to a reservoir 30 via a pipe 29. The brake fluid discharged from the discharge port 23 into the reservoir 30 is returned to the pipe 24 by a pump 31 driven by an appropriate means.

At both ends of the housing 32 of the pressure control valve 20,
A lid member 33 having a supply port 21 and a delivery port 2
2. A lid member 34 having a discharge port 23 is screwed on;
A solenoid 10, a cylindrical member 35, and a fixed pole member 36 are installed inside the solenoid 10.

The fixed pole member 36 has a projection 3 extending downward in the figure.
7, and a passage 38 and a fitting hole 39 having a larger diameter than the passage 38 are provided in the protrusion 37, and the fitting hole 39 is connected to the fixed pole member 3 through a plurality of small holes 41.
It communicates with a chamber 40 formed below 6.

Furthermore, the fixed pole member 36 is equipped with a check valve 42 that allows flow only from the chamber 40 to the supply port 21 .

The lid member 34 has a protrusion 43 that extends upward in the figure, and inside the protrusion 43, the bottom is connected to the discharge port 23.
A fitting hole 44 is bored that communicates with the fitting hole 4.
4 communicates with a chamber 46 formed in the upper part of the lid member 34 and connected to the outlet 22 through a plurality of small holes 45 .

The movable pole member 47 is slidably inserted into the cylindrical member 35 and is biased downward in the figure by a spring 48, and has a supply valve member 49 and a discharge valve member 5 inside.
0 is movably stored. The supply valve member 49 includes a valve stem 51 that fits into the fitting hole 39,
The discharge valve member 50 has a valve stem 52 that fits into the fitting hole 44.
It is equipped with

Limiting members 53, 54, 5 are provided in the movable pole member 47.
5 is fixed, and the movable range of the supply valve member 49 is restricted by restriction members 53 and 54, and the discharge valve member 50 is restricted by restriction members 54 and 55.
Further, a valve spring 56 is provided between both valve members 49 and 50.
is installed.

57, 58 and 59 indicate sealing members; 60
indicates a lead wire that supplies current to the solenoid 10. When no current is supplied to the solenoid 10, the pressure control valve 20 is in the state shown in the figure, and the valve stem 51 of the supply valve member 49 is inserted into the fitting hole 39.
The chamber 40 is in communication with the supply port 21 through the small hole 41, and the end of the valve stem 52 of the discharge valve member 50 is in contact with the bottom of the fitting hole 44, and the chamber 40 communicates with the supply port 21 through the small hole 41. (The passage from the chamber 46 to the discharge port 23 via the small hole 45 and the fitting hole 44) is closed, and the chamber 46 is cut off from the discharge port 23. When a current is supplied to the solenoid 10, an attractive force corresponding to the amount of current acts between the fixed pole member 36 and the movable pole member 47, and the movable pole member 47 moves upward against the spring 48. . Therefore, first, the valve stem 51 of the supply valve member 49 moves upward within the fitting hole 39, and the number of small holes 41 that communicate the supply port 21 and the chamber 40 decreases. That is, as the current I increases, the supply passage (from the supply port 21 to the passage 38, the fitting hole 39, the small hole 4
1 to reach the chamber 40). When the current supplied to the solenoid 10 reaches a predetermined value, the valve stem 51 of the supply valve member 49
contacts the bottom of the fitting hole 39, and the supply port 21 and the chamber 4
Cut off communication with 0. At this time, the discharge valve member 50
Since the end of the valve stem 52 remains in contact with the bottom of the fitting hole 44, the discharge passage remains closed.

Furthermore, when the current increases and the movable pole member 47 moves further upwards, the flange portion of the discharge valve member 50 comes into contact with the restriction member 55 and the discharge valve member 50 moves upward, the valve stem 52 moves into the fitting hole. 44 and communicates the chamber 46 with the outlet 23 through the small hole 45. A small hole 4 that communicates this chamber 46 with the discharge port 23
The number of 5 increases as the current increases.

Next, the operation of the embodiment will be explained with reference to FIG. 3, which shows an operation diagram.

Now, at time to, when the master cylinder 25 operates, the pressurized brake fluid is supplied to the supply port 21 of the pressure control valve 20 through the pipe 24.
It passes through the passage 38, the small hole 41, the chamber 40, and the chamber 46, and is supplied from the outlet 22 through the pipe 26 to the wheel cylinder 28 of the brake device 27, and brakes the wheels.

Then, the brake pressure P increases, and at time _t1 , the wheel slip rate reaches a predetermined value (1-η), and when the wheel speed signal V becomes smaller than the predetermined ratio η·E of the vehicle speed signal E, The output signal of comparator 7 becomes H, making switch 8 conductive. Then, the constant value V〓. A signal (V〓.-V〓) obtained by subtracting the output signal V〓 of the acceleration/deceleration calculator 3 from Supplied to solenoid 10.

At this time, the wheel is in a deceleration state and the output of the acceleration/deceleration calculator 3 is a deceleration signal, so the current supplied to the solenoid 10 is of a value sufficient to open the discharge passage. Therefore, the movable pole member 47
8, and after the supply passage closes, the discharge passage opens, and the brake fluid supplied to the wheel cylinder 28 is transferred to the piping 26, the outlet 22, and the chamber 4.
6. It is discharged into the reservoir 30 through the open discharge passage and the discharge port 23.

Therefore, the brake pressure P begins to decrease. However, even if the brake pressure P starts to decrease, the deceleration of the wheels continues to increase for a while, so the deceleration signal from the acceleration/deceleration degree calculator 3 increases, and accordingly, the deceleration signal is supplied from the amplifier 9 to the solenoid 10. The current that flows increases. Therefore, the movable pole member 47 moves further upward, and the small hole 45 that communicates the chamber 46 and the discharge port 23 is opened.
The number of brake pressure P increases, and the rate of decrease in brake pressure P increases.

When the deceleration of the wheels tends to decrease due to a decrease in the brake pressure P, the deceleration signal decreases, and therefore the output signal of the subtractor 4 decreases. Therefore, the current in the solenoid 10 becomes smaller, the movable pole member 47 moves downward due to the spring force of the spring 48, and the discharge valve member 5
0 valve rod 52 is deeply fitted into the fitting hole 44, the number of small holes 45 that communicate the chamber 46 and the discharge port 23 is reduced, and the rate of decrease in the brake pressure P is reduced.

Then, at time _t2 , acceleration/deceleration calculator 3
When the output signal of becomes zero, the constant value V〓. A current proportional to is supplied to the solenoid 10. Then, the movable pole member 47 moves further downward, and the discharge valve member 5
The end of the valve stem 52 of No. 0 comes into contact with the bottom of the fitting hole 44, and the discharge passage is closed. At this time, since the supply passage is closed, the brake pressure P remains constant.

When the wheel starts accelerating and the output of the acceleration/deceleration calculator 3 becomes an acceleration signal, the output signal (V〓.-V〓) of the subtractor 4 further decreases, and the current supplied to the solenoid 10 decreases. . Therefore, the movable pole member 47
further moves downward, and the valve stem 51 of the supply valve member 49
The tip of is away from the bottom of the fitting hole 39, that is,
The supply passage opens and the chamber 40 communicates with the supply port 21. Therefore, the brake pressure P increases. The opening degree of the supply passage at this time, that is, the supply port 21 and the chamber 4
The number of small holes 41 communicating with 0 increases in proportion to the magnitude of the acceleration signal. Therefore, the rate of increase in brake pressure P increases in accordance with the acceleration of the wheels.

Note that the timing at which the pressure control valve 20 changes from the brake pressure decreasing position to the brake pressure increasing position depends on the application and
It is not necessary to limit the setting to when the deceleration is zero, and it may be set when the acceleration of the wheel reaches, for example, 0.5 g.

The wheel speed recovers and the wheel speed signal V changes at time t ₃
When the vehicle speed signal E becomes larger than a predetermined ratio η·E, the output signal S of the comparator 7 becomes L, the switch 8 shuts off, and the current supplied from the amplifier 9 to the solenoid 10 becomes zero. Become. Therefore, the pressure control valve 20 returns to the state shown in the figure, and the foil sill 2
8, the brake pressure P increases.

When the wheel slip rate again exceeds the predetermined value (1-η) due to an increase in the brake pressure P, the above-described operation is repeated to optimally control the brake pressure.

As is clear from the above explanation, in the present invention, when the slip rate of the wheel exceeds a predetermined value, the brake pressure decreases and increases in accordance with the reduction and acceleration of the wheel, so that the brake pressure can be optimally controlled.
In particular, the brake pressure of the brake device is reduced in accordance with the acceleration/deceleration of the wheels only when the slip rate is above a predetermined value, so there is no risk of the brake pressure decreasing due to transient changes in the deceleration of the wheels. etc,
It produces excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control circuit according to an embodiment of the present invention, FIG. 2 is a sectional view including piping of a brake pressure control device, and FIG. 3 is an operation diagram showing the operation. 1...Wheel speed sensor, 2...Wheel speed calculator, 3...Acceleration/deceleration calculator, 4...Subtractor, 5
... Vehicle speed calculator, 7 ... Comparator, 8 ... Switch, 9 ... Amplifier, 10 ... Solenoid, 20
...Pressure control valve, 21... Supply port, 22... Outlet port, 23... Discharge port, 25... Master cylinder,
27...Brake device, 28...Wheel cylinder, 30...Reservoir, 31...Pump, 49...
...Supply valve member, 50...Discharge valve member.

Claims (1)

[Claims] 1. A wheel speed calculator that generates a wheel speed signal proportional to the rotational speed of the wheel, an acceleration/deceleration calculator that differentiates the wheel speed signal and generates an acceleration/deceleration signal proportional to the acceleration/deceleration of the wheel, and the wheel. A slip rate comparator that obtains a slip rate signal from a speed signal and a vehicle body speed signal proportional to the vehicle body speed, and a pressure control valve that controls the brake pressure supplied to the brake device of the wheel when the slip rate signal is generated. , in a vehicle anti-skid device that varies the rate of rise and fall of the brake pressure based on a predetermined parameter, the parameter is the acceleration/deceleration signal, and when the slip rate is equal to or higher than a predetermined value, the acceleration/deceleration signal changes. An anti-skid device for a vehicle, characterized by comprising a switching device that variably switches the rate of increase and decrease of the brake pressure depending on the magnitude of the brake pressure.