JPH0676048B2 - Anti-skidding control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an anti-skid control device that controls brake fluid pressure so as to obtain maximum braking efficiency while preventing wheel lock during control.

(Prior Art) As an anti-skid control device, a conventional device is disclosed in JP-A-55-7767.
There are the ones shown in Japanese Patent Publication No. 2 and FIG. The device of FIG. 6 comprises an actuator consisting of a solenoid valve 6 and a pump unit 7, connected to the brake fluid pressure (P _W ) lines 4 and 5 from the brake master cylinder 1 to the wheel cylinder 3 of the wheel 2. The solenoid control circuit 8 controls the current i to the solenoid 6a of the valve 6 according to the digital signals A and B from the controller (not shown),
The brake fluid pressure P _W is increased or decreased.

The pump unit 7 has a pump main body 7a and check valves 7b and 7c, and the pressure in the pipeline 9 is returned to the master cylinder 1 via the pipeline 10 by driving the pump main body 7a. When the drive current i of the solenoid 6a is 0, the valve 6 becomes the port arrangement 6b to increase the brake fluid pressure P _W ,
When i = i _1, the port arrangement 6c is established and the brake fluid pressure P _W is maintained at this value. When i = i ₂ (where i ₂ > i ₁ ), the port arrangement 6d is established and the brake fluid pressure P _W is set. _W shall be reduced.

The operation when the digital signals A and B change in level as shown in FIG. 7 will be briefly described below. From the braking start t ₀ to the instant t ₁
Until now, the A and B signals are both at "0" level, and the circuit 8
Is set to 0 and the brake fluid pressure P _W is rapidly increased to the master cylinder fluid pressure. Instantaneous t _{1 when} only the A signal becomes the “1” level
Between t ₂ and t ₂ , the circuit 8 sets i = i ₁ and maintains the brake fluid pressure P _W at the value of the instant t ₁ despite the rise of the master cylinder fluid pressure. Instantaneous t _{2 to} t ₃ when both A and B signals are at “1” level
In the meantime, the circuit 8 sets i = i ₂ to rapidly reduce the brake fluid pressure P _W. In the slow pressure-increasing region between the instants t _{3 and} t ₄ , the circuit 8 keeps both A and B signals at “0” for a fixed time d ₁ corresponding to the execution cycle of the A and B signal determination program described later with reference to FIG. Level,
Since then repeat the level change as between A signal of a predetermined time d ₂ is turn to "1" level, and the current i in a certain time d ₁ of 0 to a predetermined time d ₂ in i _1. During this time, the brake fluid pressure P
_W is pressure-increased for a certain period of time d ₁ , and then the pressure-holding control for a predetermined period of time d ₂ is repeated, and the pressure is gradually increased. Instant t ₄
In between ~t ₅ A = "1", B = brake fluid pressure P by "0"
_W is retained. In the slow decompression region after the instant t ₅ , the circuit 8 changes its level such that the A and B signals both become “1” level for a certain time d ₁ and then the B signal shifts to “0” level for a predetermined time d _3. In order to repeat the above, the current i is set to i ₂ for a fixed time d ₁ and then set to i ₁ for a predetermined time d ₃ . During this period, the brake hydraulic pressure P _W is kept constant for a certain period of time d ₁ and then kept for a predetermined period of time d _{3 so} that the brake hydraulic pressure P _W is gradually reduced.

Note that the controller that determines the levels of the A and B signals is the eighth
The control program shown in the figure is executed to make the determination. This control program is repeatedly executed in step 11 by the above-mentioned regular interruption every fixed time d ₁ , and in step 12, it is judged whether or not the pressure should be increased. If the pressure should be increased, it is determined in step 13 whether the pressure should be increased rapidly or slowly. If the pressure is increased rapidly, the A and B signals are both set to "0" in step 14 to enable the rapid increase in the brake fluid pressure. To do. If it is a gradual pressure increase, both the A and B signals are set to "0" level in step 15 to increase the brake fluid pressure for a fixed time d ₁ , and then in step 16, the gradual pressure increase timer is activated to increase the brake fluid pressure for a predetermined time d. ₂
The brake fluid pressure is gradually increased by repeating the control to maintain the pressure.

When the pressure should be maintained, the control proceeds from step 12 to step 17 to step 18, and the A signal is set to "1" level and the B signal is set to "0" level to enable the brake fluid pressure to be maintained.

If the pressure should be reduced, it is determined in step 19 whether the pressure is a sudden pressure reduction or a gentle pressure reduction. If it is a gradual depressurization, in step 21, both the A and B signals are set to the "1" level to reduce the brake fluid pressure for a fixed time d ₁ , and then step 22
To start the slow decompression timer and apply the brake fluid pressure for the specified time d ₃
The brake fluid pressure is gradually reduced by repeating the control of maintaining the pressure only.

The control reaches step 23 each time the levels of the A and B signals are determined, and the control is returned to step 11 after executing other routines.

(Problems to be Solved by the Invention) By the way, in the above description, the slower the pressure increase rate is, the higher the control accuracy can be. Especially when subtle anti-skid control is required on low-friction roads such as icy roads, the tendency to lock the wheels becomes stronger when the slow pressure increasing speed is high.
This causes a decrease in control efficiency.

Therefore, in order to moderate the slow pressure increasing speed, the pressure increasing pulse width
Even if the d ₁ is made smaller, this pulse width cannot be made smaller than the execution period d _{1 of the} control program shown in FIG. 8 which is executed by the controller in determining the level of the A and B signals, which is naturally restricted. . Alternatively, it is conceivable to increase the holding pressure pulse width d _2, slow increase圧周life longer represented by the sum of this pressure increase pulse width d ₁ and the pressure-holding pulse width d _2, the wheels It cannot be adopted because it cannot keep up with the behavior.

It is an object of the present invention to eliminate the above-mentioned restriction by making the pulse width of the pressure boosting pulse smaller than the execution cycle of the control program so as to contribute to the slow pressure boosting of the antiskid control.

(Means for Solving the Problem) For this purpose, the present invention determines whether the brake fluid pressure is reduced or kept by determining the wheel lock state by a control program repeatedly executed at regular intervals. When deciding whether to increase the pressure slowly or suddenly, and to judge that the brake fluid pressure should be increased gradually, by alternately outputting the pressure increasing pulse and the pressure maintaining pulse having the pulse width determined by the execution cycle of the control program. In the anti-skid control device for gradually increasing the brake fluid pressure in a stepwise manner, a pressure increasing pulse width changing means for making the pulse width of the pressure increasing pulse smaller than the execution cycle of the control program is provided. It is what

(Operation) The anti-skid control device determines the lock state of the wheel by the control program repeatedly executed at regular intervals, and reduces the brake fluid pressure, maintains the pressure, slowly increases the pressure, or rapidly increases the pressure. Determine which and implement these to prevent wheel locking.

Here, when it is determined that the brake fluid pressure should be gradually increased, the brake fluid pressure is gradually increased by the alternating output of the pressure increasing pulse and the pressure holding pulse having the pulse width determined by the execution cycle of the control program. Increase pressure.

By the way, the pressure increasing pulse width changing means at the time of this gentle pressure increasing is
The pulse width of the pressure boosting pulse is made smaller than the execution cycle of the control program. Therefore, the gradual pressure increase rate can be moderated by that amount to improve the control accuracy. For this reason, even if a subtle anti-skid control is required especially on a low-friction road such as an icy road, the control can be performed as requested, and it is possible to prevent the locking tendency of the wheels from becoming strong and the braking efficiency from decreasing. it can.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 1 shows an embodiment of the present invention. In this embodiment, the following pressure increasing pulse width changing means 30 is provided in connection with the A signal input terminal of the solenoid control circuit 8 described above.

This means is composed of monostable multivibrators 31, 32 and NOT gate 36 to which the A signal is input.

The monostable multivibrators 31 and 32 are each triggered by the falling edge of the A signal.
31 is a negative pulse E having a width of 5 msec from the trigger, which is the same as the fixed time d ₁ (execution cycle of the control program shown in FIG. 8).
Further, the monostable multivibrator 32 outputs a negative polarity pulse F having a width of 3 msec, which is shorter than the period d ₁ for executing the control program from the trigger.

The OR gate 34 takes the logical sum of the signals E and F and supplies the I output to the AND gate 36. The exclusive OR gate 35 receives the A signal inverted output from the NOT gate 33 and the signal E, and outputs the output H. Supply to AND gate 36. This AND gate 36
Is to AND the signals H and I to supply the output J to the solenoid control circuit 8.

The operation of the above embodiment will be described below in the case where the A signal and the B signal are as shown in FIG.

In Figure 2, until instant t ₁ A signal is "1" level, B
Signal a coercive pressure range becomes "0" level, while instant t ₁ ~t ₂ is B signal maintains "0" level, the A signal of a predetermined time d ₁ "0" level and the predetermined time d ₂ This is a slow pressure increasing region in which the "1" level is repeated alternately, and the B signal is "0" between the instants t ₂ and t _3.
Maintaining the level, a surge pressure range which A signal is constant time d ₁ or more "0" level, the instant t ₃ thereafter a vacuum region A, B signals are both "1" level.

Each time the A signal falls, the monostable multivibrator 31
Is a negative pulse E having a width of 5 msec (same as d ₁ ), the monostable multivibrator 32 outputs a negative pulse F having a msec width, and the OR gate 34 to which these are inputted has a negative pulse having the same waveform as F. Generate I.

On the other hand, the NOT gate 33 inverts the A signal to generate the G signal, and the exclusive OR gate 35 outputs the signal H of "1" level as long as the G signal and the E signal are different. Then, the AND gate 36 outputs the signal J by logically ANDing the signals H and I, and the negative pulse of the signal J replaces the original negative pressure boosting pulse signal A, and the pulse width is reduced. Boosting pulse. The solenoid control circuit 8 outputs the signals J and B
The drive current i of the solenoid 6a (see FIG. 6) is controlled in three stages as shown in FIG. 2 based on the signal.

Therefore, the pressure increasing pulse width is made smaller than the control program execution period d _{1 in} FIG. 8 in the slow pressure increasing region between the instants t ₁ and t _2, and the slow pressure increasing speed is moderated accordingly and the control accuracy is reduced. Can be increased. Incidentally, during pressure increase in initially in surge pressure range between instant t ₂ ~t ₃ 3 msec, but is between the holding pressure of the subsequent 2 msec, that this holding pressure is to hinder the rapid increase of very short brake fluid pressure There is no.

In this way, increasing the speed of slow pressure increase to improve the accuracy of anti-skid control makes it possible to perform the required control even when a subtle anti-skid control is required, especially on a frozen road, and the tendency of the wheels to lock. It is possible to prevent the strength from becoming stronger and the braking efficiency to decrease.

FIG. 3 shows that in the above-mentioned embodiment, the pressure increasing pulse width for slow pressure increasing which is smaller than the control program execution period d ₁ is fixed to 3 msec. An example is shown in which the value that matches the friction coefficient can be set. In this case, it is possible to prevent the slow pressure increase speed from being unnecessarily slowed down excessively, and to prevent the anti-skid control device from causing a delay in the increase of the brake fluid pressure, and it is possible to prevent a decrease in braking efficiency.

Therefore, in this example, the pressure increasing pulse width changing means 30 is configured so that the pressure increasing pulse width for slow pressure increasing can be changed by the combination of the levels of the digital signals D and D '. That is, the means 30 is D,
In addition to having NOT gates 41 and 42 that invert the D'signal and output, AND gate 43 that takes the logical product of the output of the NOT gate 41 and the D'signal, and the logical product of the output of the NOT gate 42 and the D signal Take A
ND gate 44 and AND gate 45 that takes the logical product of D and D'signals
To provide.

The boosting pulse width changing means 30 is further supplied with the positive monostable multivibrators 46 to 48 supplied with the outputs E _{1 to} E ₃ of the AND gates 43 to 45 and the outputs F _{1 to} F ₃ from them. Negative monostable multivibrators 49 to 51, an OR gate 52 supplied with outputs G _{1 to} G ₃ from these, and an output A ′ from the output of this OR gate and the A signal is solenoid 8 '. And an OR gate 53 for supplying

The monostable multivibrators 46 to 48 are respectively triggered by the rising edges of the signals E _{1 to} E ₃ to generate positive pulse signals F _{1 to} F ₃ having a width of 2 msec, 3 msec and 4 msec, and the monostable multivibrators 49 to 51 are Triggered by the falling edge of the signals F _{1 to} F ₃ , respectively, and positive polarity pulse signals G _{1 to} G _{3 of} 3msec, 2msec, 1msec width
To occur. An OR gate that takes the logical sum of these signals G _{1 to} G ₃
The output H of 52 is supplied to the OR gate 53 together with the A signal.
The output A'from the OR gate 53 is supplied to the solenoid control circuit 8 instead of the A signal.

In such a configuration, the pressure increasing pulse width for slow pressure increase is determined by the combination of the levels of the signals D and D ', but the controller for determining the levels of the signals D and D'is the levels of the A and B signals. It is assumed that the control program is executed and determined according to the required slow pressure increasing speeds I to IV.

This control program is also repeatedly executed at intervals of a fixed time d ₁ and is basically the same as in FIG. 8, but the levels of the A signal and the B signal are determined in steps 14, 18, 20, 21. At this time, both signals D and D'are set to "0" level, and OR is used for rapid pressure increase other than slow pressure increase, sudden pressure decrease, slow pressure decrease, and pressure holding.
By keeping the output of the gate 52 at "0", the output A'of the OR gate 53 has the same waveform as the A signal, so that the brake fluid pressure control similar to the normal operation is performed.

When a slow pressure increase request is made, it is determined in steps 61 to 63 which one of the slow pressure increase speeds I to IV is preferable according to the road surface condition.
With the signal at "0" level and the D'signal at "1" level, step 65, as the preferred speed increases to II, III, IV.
Set the levels of D and D'signals like 66 and 67. Then, by executing steps 15 and 16, the brake fluid pressure is gradually increased at the above-mentioned set speed.

The effect of this example is that the A and B signals are as shown in FIG. 5, and the instants t _{1 to} t
_{The case} where the D'signal is set to "1" during the control program execution period d ₁ because the required speed of slow pressure increase between I and I is I will be described. At this time the third figure E _2, E ₃ signal keeps the "0" level, the output H of the OR gate 52 is determined by E ₁ signal, E ₁ signals as Figure 5 D 'signal and the waveform Becomes The F ₁ signal becomes “1” level for 2 msec from the rise of the E ₁ signal, and then the G ₁ signal becomes “1” level for 3 msec and the H signal of the same waveform is generated. OR that takes the logical sum of this H signal and A signal
The output A ′ of the gate 53 becomes “0” level for 2 msec from the instant t ₁ and is supplied to the solenoid control circuit 8 instead of the A signal. As a result, the pressure increasing pulse width during the slow pressure increasing is controlled by the control program execution period d. It can be set to 2 msec which is smaller than ₁ , and can achieve the same purpose as the above-mentioned example.

In addition, in this example, as in step 65 in FIG.
If the signal is set to "1" level and the D'signal is set to "0" level, the pressure increasing pulse width during slow pressure increasing is set to 3 msec and the slow pressure increasing speed is set to II.
Can be changed to D, as in step 66,
If both D'signals are set to "1" level, the pressure increasing pulse width during slow pressure increasing can be set to 4 msec and the slow pressure increasing speed can be changed to III. Furthermore, as in step 67, both D and D'signals are changed. If it is set to "0" level, the pressure increasing pulse width during slow pressure increasing is 5 msec.
The slow pressure increasing speed can be changed to IV.

For this reason, in this example, the slow pressure increasing rate can be changed to a suitable value for each road surface state, the same operational effect as that of the above embodiment can be obtained on any road surface, and the slow pressure increasing rate is unnecessarily slow. It is possible to prevent the anti-skid control device from causing a delay in increase of the brake fluid pressure, and it is possible to prevent the braking efficiency from decreasing.

(Effects of the Invention) Thus, the antiskid control device of the present invention, as described above,
Since the means 30 for reducing the pressure increasing pulse width during the gradual pressure increase to less than the execution period d ₁ of the anti-skid control program is provided, the gradual pressure increase speed can be slowed to improve the accuracy of the anti-skid control. For this reason, even if a subtle anti-skid control is required especially on a low-friction road such as an icy road, the control can be performed as requested, and it is possible to prevent the locking tendency of the wheels from becoming strong and the braking efficiency from decreasing. it can.

[Brief description of drawings]

FIG. 1 is an electronic circuit diagram of an essential part showing an embodiment of the invention anti-skid control device, FIG. 2 is an operation time chart thereof, and FIG. 3 is an electronic circuit diagram of an essential part showing another example of the present invention. 4 is a flowchart of a control program for determining an input signal in the same example, FIG. 5 is an operation time chart of the device of the same example, FIG. 6 is a system diagram showing a general configuration of an antiskid control device, and FIG. 7 is the same. An operation time chart thereof and FIG. 8 are flowcharts showing the control program. 1 …… Brake master cylinder, 3 …… Wheel cylinder 6 …… Solenoid valve, 7 …… Pump unit 8 …… Solenoid control circuit, 30 …… Pressure increasing pulse width changing means 31,32,46 to 51 …… Mono-stable Multivibrator 33,41,42 …… NOT gate 34,52,53 …… OR gate 35 …… Exclusive OR gate 36,43 to 45 …… AND gate

Claims (2)

[Claims] 1. A control program repeatedly executed at regular intervals to determine a wheel lock state and determine whether to reduce, maintain, slowly increase, or rapidly increase the brake fluid pressure. When it is determined that the brake fluid pressure should be gradually increased, the brake fluid pressure is gradually increased in a stepwise manner by alternately outputting a pressure increasing pulse and a pressure holding pulse having a pulse width determined by the execution cycle of the control program. The anti-skid control device as described above, further comprising pressure-increasing pulse width changing means for making the pulse width of the pressure-increasing pulse smaller than the execution cycle of the control program. 2. The anti-skid control device according to claim 1, wherein the pressure increasing pulse width changing means can set the pressure increasing pulse width to various values.