JPS6341782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid 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 when the rate of decrease in the rotational speed of the wheel, that is, the deceleration of the wheel, exceeds a predetermined reference value, it is determined that the wheel skid has started. It is determined that the brake pressure supplied to the brake device of the wheel decreases, and when the decrease in brake pressure causes the deceleration of the wheel to become smaller than a predetermined reference value, the brake pressure is increased.

By the way, in conventional anti-skid devices, when the deceleration of the wheels exceeds a predetermined reference value,
The brake pressure decreases at a constant rate of decrease regardless of the magnitude of the deceleration, so when the deceleration increases rapidly, the rate of decrease of the brake pressure is too small and the rotational speed of the wheels decreases more than necessary. Too much,
Also, when the deceleration is increasing slowly,
There was a drawback that the rate of decrease in brake pressure was too high, causing the brake pressure to decrease more than necessary. In addition, when the wheel deceleration becomes smaller than a predetermined reference value, the brake pressure increases, so when the rate of decrease in the wheel deceleration is small, the brake pressure increases too much before the wheel rotational speed recovers sufficiently, causing the wheel The drawback was that the slip rate was too large.

Furthermore, Japanese Patent Application Laid-Open No. 49-132468 describes a system that controls the rate of decrease in brake pressure according to the magnitude of the friction coefficient μ between the road surface and the wheels, but the attenuation or recovery of the wheel speed is not as described above. This is not caused only by the friction coefficient μ. That is, the attenuation or recovery of the wheel speed varies greatly depending on the brake torque at that time. Therefore, if the rate of decrease in brake pressure is controlled using the friction coefficient μ as a parameter as shown in the prior art, even under conditions where the friction coefficient μ is the same, for example, if the brake torque is excessive, the brake pressure will actually increase further. Even if the wheels would slip significantly if the rate of decrease in brake pressure is not increased, the brake pressure decreases insufficiently because the rate of decrease in brake pressure is constant, causing the wheels to slip significantly and the vehicle to become unstable. In addition, even if the brake torque is small and there is no need to actually increase the rate of decrease in brake pressure, with conventional brake pressure the rate of decrease is constant, so the decrease in brake pressure is excessive and the braking distance is extended. There is a drawback.

The present invention has been made in view of the above drawbacks, and detects wheel skidding by comparing the rotational speed of the wheels and the vehicle body speed, and when the rotational speed of the wheels becomes less than a predetermined percentage of the vehicle body speed. , the brake pressure decreases at a rate of decrease corresponding to the deceleration of the wheels,
An anti-skid skid for vehicles that increases the brake pressure rapidly when the rotational speed of the wheels tends to recover and the acceleration of the wheels exceeds a predetermined acceleration reference value, thereby optimally controlling the brake pressure of the wheels. The purpose is to provide equipment.

In other words, the rate of decrease in brake pressure is controlled according to the deceleration of the wheels, which is determined comprehensively by the friction coefficient μ between the road surface and the wheels, the brake torque, etc., and at the same time, the speed at which the brake pressure decreases is controlled to ensure that the acceleration of the wheels exceeds a predetermined value. This is the first time the brake pressure is suddenly increased.

Embodiments of the present invention will be described below 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 rotating part of a wheel or a propeller shaft that rotates together with the wheel, and generates a pulse signal with a frequency proportional to the rotational speed of the wheel. This pulse signal is converted by the wheel speed calculator 2 into a wheel speed signal V proportional to the rotational speed of the wheel.

The acceleration/deceleration calculator 3 differentiates the wheel speed signal V from the wheel speed calculator 2 and generates an acceleration/deceleration signal V which is proportional to the acceleration and deceleration of the wheels.

This acceleration/deceleration signal V〓 is compared with an acceleration reference value + _B1 corresponding to an acceleration of 2 g, for example, by the acceleration control signal generator 4, and when the acceleration/deceleration signal V〓 exceeds the reference value + _B1 , an acceleration control signal is generated. The output signal + _b1 of the device 4 becomes "H".

Further, this acceleration/deceleration signal V〓 is transmitted to the acceleration discriminator 5, and when acceleration occurs in the wheel and the acceleration/deceleration signal becomes an acceleration state, the output signal + _b0 of the acceleration discriminator 5 becomes "H".

The vehicle speed calculator 6 receives the wheel speed signal V from the wheel speed calculator 2 and the vehicle deceleration device -α from the vehicle deceleration detector 7, and is normally kept at the same value as the wheel speed signal. , when the rate of decrease of the wheel speed signal exceeds a predetermined value, the vehicle body deceleration detector 7
A vehicle speed signal E is generated that decreases at a rate corresponding to the detected vehicle deceleration.

This vehicle speed signal E is compared with a wheel speed signal V by a comparator 8, and the wheel speed signal V becomes a predetermined percentage of the vehicle speed signal E, for example, 95% or less, that is, the wheel slip rate is 5% or more. Then, the output signal S of the comparator 8 becomes "H".

The AND gate 9 receives the output signal + _b1 of the acceleration control signal generator 4 and the output signal S of the comparator 8,
When the output signal + _b1 is "L" and the output signal S is "H", the output becomes "H".

The control amplifier 10 receives output signals from the acceleration discriminator 5, the acceleration/deceleration calculator 3, and the AND gate 9,
When the output signal of the AND gate 9 is "L", the current to the solenoid 11 of the pressure control valve is zero, but when the output signal of the AND gate 9 becomes "H", current is supplied to the solenoid 11. and,
When the output signal +b ₀ of the acceleration discriminator 5 is "H", the magnitude of this current is maintained at a constant value I ₀ necessary to close the supply valve of the pressure control valve as described later, and the output signal When +b ₀ is "L", control is performed according to the magnitude of the output signal of the acceleration/deceleration calculator 3. That is, it is small when the deceleration signal is small, and becomes large when the deceleration signal is large.

Next, FIG. 2, which shows a brake pressure control device including a pressure control valve, will be described.

The pressure control valve, generally designated 20, has a supply port 21,
The supply port 21 is connected to the master cylinder 25 via a pipe 24, and the delivery port 22 is connected to a wheel brake device 2 via a pipe 26.
The discharge port 23 of the wheel cylinder 28 of No. 7 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 11, a cylindrical member 35, and a fixed pole member 36 are installed inside the solenoid 11.

The fixed pole member 36 is provided with a passage 38 in which a supply valve seat 37 is formed at its tip, and is also provided with a check valve 41 . Then, the check valve 41 is connected to the fixed pole member 36
Only the flow from the chamber 39 formed on the lower side to the supply chamber 40 connected to the supply port 21 is allowed.

The movable pole member 42 is slidably inserted into the cylindrical member 35 and is biased downward in the drawing by a spring 43, and the supply valve member 44 and the discharge valve member 4 are inserted inside the movable pole member 42.
5 is movably stored. The movement of the supply valve member 44 is restricted within a predetermined range by restriction members 46 and 47 positioned within the movable pole member 42, and the movement of the discharge valve member 45 is restricted within a predetermined range by restriction members 47 and 48. A valve spring 49 is stretched between both valve members 44 and 45.

The lid member 34 has a valve seat portion 50 extending upward, and a fitting hole 52 into which the protrusion portion 51 of the discharge valve member 45 fits is provided in the valve seat portion 50. The fitting hole 52 communicates with the discharge port 23 at the bottom and also communicates with a delivery chamber 54 formed below the movable pole member 42 via a plurality of small holes 53 arranged in the vertical direction.

55, 56 and 57 indicate seal rings; 5
Reference numeral 8 indicates a lead wire that supplies current to the solenoid 11. In the state shown in the figure in which no current is supplied to the solenoid 11, the movable pole member 42 is pressed downward in the figure by the spring 43, the supply valve member 44 is separated from the supply valve seat 37, and the discharge valve member 45
The tip of the projection 51 is in contact with the bottom of the fitting hole 52. That is, the supply passage (supply valve member 44
and the supply valve seat 37) is open, and the discharge passage (the passage from the delivery chamber 54 through the small hole 53 and the fitting hole 52 to the discharge port 23) is closed.

Therefore, the supply port 21 is connected to the supply chamber 40, the passage 38,
Supply passage, through holes 59 and 60 provided in the flanges of the supply valve member 44 and the discharge valve member 45, and the delivery chamber 5
4 to the outlet 22, and the outlet chamber 54 is isolated from the outlet 23 by a closed outlet passage.

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

Now, when the master cylinder 25 operates at time t ₀ , the pressurized brake fluid is supplied to the supply port 21 of the pressure control valve 20 through the pipe 24 , through the passage 38 , the supply passage, the through holes 59 , 60 , Delivery chamber 54
is supplied to the wheel cylinder 28 of the brake device 27 from the outlet 22 through the pipe 26,
The brakes are applied to the vehicle. Then, the brake pressure P increases, and at time _t1 , the wheel speed signal V
becomes less than a predetermined ratio ηE of the vehicle speed signal E,
The output signal S of the comparator 8 becomes "H". At this time,
Since the wheel speed signal V is in a decreasing state and the output signal + _b1 of the acceleration control signal generator 4 is "L",
The output signal of AND gate 9 becomes "H". Note that the output signal +b ₀ of the acceleration discriminator 5 is also "L". Therefore, the current corresponding to the deceleration signal from the acceleration/deceleration calculator 3 flows from the control amplifier 10 to the pressure control valve 2.
0 solenoid 11.

If the current supplied from this control amplifier to the solenoid 11 is I, the current I is the acceleration discriminator 5
Proportional to the constant current I ₀ sent from the control amplifier 10 when the output signal +b ₀ becomes “H” and the absolute value of the acceleration/deceleration signal V〓 from the acceleration/deceleration calculator 3 |V〓| It is given by the sum of the current I _c .

When a current I is supplied to the solenoid 11 of the pressure control valve 20, an attractive force proportional to the current I is generated between the fixed pole member 36 and the movable pole member 42, and the movable pole member 42 The supply valve member 44 moves upward against the force, and first the supply valve member 44 seats on the supply valve seat 37 to close the supply passage, and then the movable pole member 42 moves upward against the spring force of the spring 43 and the valve spring 49. Move to. Therefore, the discharge valve member 45 comes into contact with the restriction member 48 and moves upward, and the protrusion 51 of the discharge valve member 45 moves relative to the fitting hole 52, and the delivery chamber 54 is moved between the small hole 53 and the fitting hole 52. It communicates with the discharge port 23 via. In other words, the discharge passage is opened.

At this time, the number of small holes 53 communicating the delivery chamber 54 and the discharge port 23, that is, the opening degree of the discharge passage is determined by the amount of upward movement of the discharge valve member 45, that is, the magnitude of the current supplied to the solenoid 11. Depends on the situation. When the discharge passage opens, the brake pressure fluid in the wheel cylinder 28 is discharged through the pipe 26, the outlet 22, and the outlet chamber 5.
4, is discharged to the reservoir 30 through the small hole 53, the discharge port 23 and the pipe 29, and the brake pressure P begins to decrease.

However, even if the brake pressure P starts to decrease due to hysteresis of the brake device 27 or the like, the wheel deceleration signal continues to increase for a while. Therefore, the current supplied to the solenoid 11 increases accordingly, the discharge valve member 45 moves further upward, and the rate of decrease in brake pressure increases.

Then, the amount of decrease in brake pressure increases,
When the deceleration of the wheel, that is, the deceleration signal output from the acceleration/deceleration calculator 3, begins to decrease, the current I supplied to the solenoid 11 decreases accordingly, and the movable pole member 42 is activated by the spring 43 and the valve spring 49. Due to the spring force of
The number of 3s decreases. Therefore, the rate of decrease in brake pressure P becomes smaller.

When the brake pressure P decreases and the wheels start accelerating at time _t2 , the output signal + _b0 of the acceleration discriminator 5 becomes "H". Then, the output current of the control amplifier 10 decreases to a predetermined current I ₀ .

Therefore, the movable pole member 42 is moved downward by the spring force of the spring 43 and the valve spring 49, and the discharge valve member 4
The tip of the protrusion 51 of No. 5 abuts the bottom of the fitting hole 52, blocking communication between the delivery chamber 54 and the discharge port 23. That is, the discharge passage is closed. However, the supply valve member 44 remains seated on the supply valve seat 37, that is, the supply passage remains closed.

Therefore, the brake pressure P of the wheel cylinder 28 becomes constant.

In addition, during the brake pressure reduction process, the brake fluid discharged from the discharge port 23 into the reservoir 30 is pressurized by the pump 31 and returned to the pipe 24.

When the acceleration of the wheel increases and the acceleration signal from the acceleration/deceleration calculator ₃ exceeds the reference value + _B1 at time t3, the output signal + _b1 of the acceleration control signal generator 4 becomes "H". Then, the output signal of the AND gate 9 becomes "L", and the current supplied from the control amplifier 10 to the solenoid 11 of the pressure control valve 20 becomes zero. Therefore, the attractive force acting between the fixed pole member 36 and the movable pole member 42 disappears, the movable pole member 42 is moved downward by the spring 43, and the supply valve member 44 is separated from the supply valve seat 37. Then, the state returns to the state shown in the figure, and the brake pressure P of the wheel cylinder 28 is increased.
rises rapidly.

The rising speed of this brake pressure is determined by the rate at which the fixed pole member 3
It is determined by the constricted area of the constricted portion 61 of the passage 38 of No. 6.

When the acceleration signal from the acceleration/deceleration calculator 3 becomes smaller than the acceleration reference value +B1 at time _t4 due to an increase in the brake pressure P, _{the acceleration control signal +B1 becomes} "L" again, and the output of the AND gate 9 The signal becomes "H". Therefore, since the output signal + _b0 of the acceleration discriminator 5 is "H", the current supplied from the control amplifier 10 to the solenoid 11 is _I0 again.
become.

Therefore, the movable pole member 42 of the pressure control valve 20 moves upward against the spring force of the spring 43, the supply valve member 44 seats on the supply valve seat 37, and the supply passage is closed. At this time, the discharge passage is kept closed, so the brake pressure P remains constant.

The rotational speed of the wheels is restored, and at time _t5 , the wheel speed signal V of the wheel speed calculator 2 becomes larger than the predetermined ratio ηE of the vehicle speed signal E of the vehicle speed calculator 6, and the output signal of the comparator 8 When S becomes "L", the output signal of AND gate 9 becomes "L",
The output current of the control amplifier 10 becomes zero.

Therefore, the pressure control valve 20 is demagnetized and the brake pressure P of the wheel cylinder 28 increases again.

Thereafter, by repeating this operation, the brake pressure can be optimally controlled.

As is clear from the above description, the present invention compares the rotational speed of the wheels and the vehicle body speed, and when the slip rate of the wheels exceeds a predetermined value, brakes are applied at a decreasing speed corresponding to the magnitude of the deceleration of the wheels. Since the pressure decreases, the brake pressure can be optimally controlled according to the magnitude of wheel deceleration, and the brake pressure increases rapidly only when the wheel acceleration is above a predetermined reference value, so the brake pressure can be controlled optimally depending on the magnitude of wheel deceleration. This has remarkable effects such as being able to prevent an increase in the slip rate due to an unnecessarily increased increase in the slip rate.

[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 partial sectional view including a piping system of the brake pressure control device, and FIG. 3 is an operation diagram showing the operation. DESCRIPTION OF SYMBOLS 1... Wheel speed sensor, 2... Wheel speed calculator, 3... Acceleration/deceleration calculator, 4... Acceleration control signal generator, 5... Acceleration discriminator, 6... Vehicle speed calculator, 8... Comparator, 10... Control amplifier, 1
1... Solenoid, 20... Pressure control valve, 25...
...Master cylinder, 28...Wheel cylinder,
27...brake device, 37...supply valve seat, 44
... Supply valve member, 45 ... Discharge valve member, 51 ...
Projection, 52...fitting hole, 53...small hole.

Claims (1)

[Claims] 1. A wheel speed calculator that generates a wheel speed signal proportional to the rotational speed of the wheel, a vehicle speed calculator that generates a vehicle speed signal proportional to the vehicle speed, and a vehicle speed calculator that differentiates the wheel speed signal and calculates the acceleration/deceleration of the wheel. an acceleration/deceleration calculator that generates an acceleration/deceleration signal proportional to the
a pressure control valve that controls the brake pressure supplied to the brake device of the wheel, and controls the brake pressure of the brake device when the wheel speed signal becomes equal to or less than a predetermined ratio of the vehicle body speed signal, Further, in a vehicle anti-skid device that controls the rate of decrease of the brake pressure based on a predetermined parameter, the parameter is the acceleration/deceleration signal, and when the wheel speed signal is in a decreasing state, an electric current corresponding to the acceleration/deceleration signal is provided. is supplied to the pressure control valve, so that the brake pressure of the brake device decreases at a rate of decrease corresponding to the deceleration of the wheels, and when the acceleration/deceleration signal exceeds a predetermined acceleration reference value, the brake pressure of the brake device decreases at a rate corresponding to the deceleration of the wheels. An anti-skid device for a vehicle characterized by a rapid increase in brake pressure.