JPS61202964A - Brake magnification device - Google Patents

Abstract

PURPOSE:To keep the continuation of a wheel lock condition to a minimum by prohibiting a rise of the boost force changed in response to the depression force of a brake pedal when a wheel is detected to be put in a lock condition. CONSTITUTION:A brake magnification device 2 normally controls the boost force so that the car deceleration is changed at the constant relationship with the depression force of a brake pedal 1. In this case, a wheel lock detection means 3 detecting that a wheel is put in a lock condition is provided. When this detection means 3 detects a wheel lock condition, a boost force rise prohibition means 4 controls the boost force to prohibit its rise while a wheel is locked. Accordingly, it can be prevented that the depression quantity of the brake pedal 1 becomes abnormally large during a wheel lock condition and the operation feeling of the brake pedal is deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a brake booster used in a vehicle brake system for the purpose of boosting the pedal effort.

(Prior art) Various types of brake boosters, such as hydraulic and vacuum types, are known.
No. 498 discloses a groove bottom that controls boost force so that vehicle deceleration changes in a constant relationship with respect to brake pedal depression force without being affected by changes in vehicle body load or wear of brake friction material over time. A brake booster has already been proposed, which is a problem that the invention aims to solve.
As shown in the figure, when the vehicle deceleration αR has reached a peak due to wheel locking, the boost force B is used to compensate for the lack of vehicle deceleration α, even when the brake pedal depression force Fr is not increased. It will continue to rise. Therefore, in this case, although it is necessary to reduce the boost force in order to release the wheel lock, the boost force increases and the stopping distance increases due to the locking of the wheels. In addition, an increase in boost force makes the amount of depression of the brake pedal abnormally large, which worsens the operating feeling of the brake pedal and delays the decrease in braking force when the brake pedal is released, resulting in a delay in braking release. This may result in longer stop distances.

(Means for Solving the Problems) In order to solve these problems, the present invention is designed so that the vehicle deceleration changes in a constant relationship with the depression force of the brake pedal 1, as shown in FIG. Boost power M1
The brake booster 2 is equipped with a wheel lock detection means 8 for detecting when the wheels are locked, and a boost torque rise inhibiting means for prohibiting the boost torque from rising while the wheels are locked. be.

(Function) The brake booster 2 normally controls the boost force so that the vehicle deceleration changes in a constant relationship with the depression force of the brake pedal 1. By the way, when the wheels are locked, the means 8 receives a signal from the means 8 for detecting this and detects this.
Prohibits an increase in boost force, which tends to increase due to insufficient vehicle deceleration due to wheel lock. Therefore, it is possible to reduce the occurrence of this condition when the wheels are locked, and it is also possible to prevent the depressing field of the brake pedal from becoming abnormally large when the wheels are locked. At the same time, the braking force can be quickly reduced when the brake pedal is released, and a delay in releasing the brake can be avoided.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Figure 2 shows an embodiment of the brake booster of the present invention.
0 indicates the booster main body, and 11 indicates a solenoid valve. Main body 10
comprises a shell 12, the interior of which is divided by a piston 18 and a diaphragm 14 into two chambers i+16. A bushing rod 17 and an operating rod 18 are attached to the piston 18, the bushing rod 17 penetrates the chamber 15 and projects from the shell 12, and abuts against the piston of a brake master cylinder (not shown), and the operating rod 1B penetrates the chamber 1B and projects from the shell 12. It projects from the shell 12 and is connected to a brake pedal (not shown) via a clevis 19. A return spring zO is arranged in the chamber 15, and acts on the piston 1B to elastically move the piston 18 to the rightmost position shown in the figure.

When the brake pedal is depressed, the operating rod 18 is moved to the left in the drawing, and the brake master cylinder is actuated via the bushing rod 17 to brake the vehicle. During this time, the main body 10 applies a force (boost force) to the operating rod 1 according to the pressure difference within the chambers 15 and 16.
8 and the bushing rod 17 to the left in the figure to assist in pressing the brake pedal.

In order to be able to control such boosting force, chamber 1
5 is in contact with the constant negative pressure source 22 through the conduit 21, but the chamber 16
is in contact with the control pressure outlet boat 24 of the solenoid valve 11 through a conduit 28. The magnetic valve 11 also has a negative input boat 25 that communicates with a constant negative pressure source 22 and a high pressure inlet boat 27 that communicates with a constant high pressure source 2B, allowing the boat 24 to selectively communicate with the boat 25.27. The control pressure from the boat 24 to the chamber 16 is adjusted or the boat 24 is isolated from the boat 25, 27 to maintain the control pressure from the boat 24 as it is.

For this purpose, the solenoid valve 11 comprises a compressible valve body 28 and a rigid valve body 29, the valve body 29 being held in the closed position shown by a spring 80, and in this closed position the valve body 28 is held by a spring 31 as shown in the figure. The ball is supported in the open position. A solenoid 82 is provided to lower the valve body 29 in the figure, and this solenoid has a size proportional to the current i when energized! ! Valve body 2 due to 1ili force
9 is lowered in the figure from the position shown.

The current i to the solenoid 82 is set to 8 by the controller 38.
Control is performed in stages, and when 1=00, the valve bodies 2B and 29 are springs 80
, ill connects the boat 24 to the boat 25, but it is disconnected from the boat 27, and when i-1□, the electromagnetic force of the solenoid 82 causes the valve body 29 to close as shown in the figure and close the valve. The body 2B is lowered in the figure to the closed position, and the boat 24 is moved (bow) 25, 2? When soil = is (is > i□), solenoid lll5
By further lowering the valve body 29 while keeping the valve body 28 in the closed position by a larger electromagnetic force, the boat 24 is cut off from the boat 25, but the boat 24 is opened to the boat 27.

The controller B8 is provided with the operating gland 18 and inputs the brake pedal depression force F.
A signal from the pedal force detection means 84 that detects T, a signal from the wheel speed detection means 85 that detects the rotational speed vw of a wheel (not shown), and a signal from the deceleration detection means 86 that detects the deceleration αR of the vehicle. Input the respective signals. controller 88
As shown in Figure 3, the central processing unit ((3PU) 88
a, Random access memory (R eave) a8cSA/D
Converter 88d1 output inter 7 ace circuit (Ilo)
88e and an amplifier 88f, and executes the control programs shown in FIGS. 4 and 5 based on the above input information to control the drive current 1 of the solenoid valve 11S, specifically the solenoid 82, in three stages. It shall be.

FIG. 4 shows the main routine. First, in step 40, the brake pedal depression force Fp is read, and the next step 41
The target deceleration αi of the vehicle corresponding to the brake pedal depression force Fp is calculated T. In the next step %2, the actual deceleration αR of the vehicle is read, and in the next step 43, the actual deceleration αR is read.
and the target deceleration αi. If αi is smaller than αR, that is, if the boost force is excessive and the deceleration αR is too large with respect to the target αi, i-0 is set in step 44 and then output in step 45. When i=0, the solenoid valve 11 connects the boat 24 to the boat 25 to bring the pressure in the chamber 18 close to the constant negative pressure in the chamber 15, as described above.

Therefore, the boost force determined by the pressure inside the chamber 15116 is reduced, and the deceleration αR can be brought closer to the target αi.

If it is determined in step 48 that αi; αR, that is, if the boost force is just right and the deceleration α matches the target α1, 1=10 is set in step 46, and then this is output in step 45. When this i-value is 1□, the solenoid valve 11
As described above, the boat 24 is isolated from the boat 25, 27 so that the pressure in the chamber 16 does not change. Therefore, the boost force remains unchanged, and the state where the deceleration αR matches the target αi is l! Read.

If it is determined in step 48 that αi>αR, it is checked in step 47 whether or not the wheels are locked in order to determine whether the insufficient deceleration is due to the wheels being locked or due to insufficient boost force. This check is executed by the subroutine shown in FIG. 5, and first, in step '50, the wheel speed vw is read. In the next step 51, it is determined whether this wheel svw is 0 or not, and if ■w=lIO, it is determined that the wheel is locked in step 52, and if 7w4o, it is determined that the wheel is unlocked in step 53, and the control is performed as shown in FIG. Back to routine.

If the wheels are unlocked, step 47 selects step 48; if the wheels are locked, step 46 is selected. If the wheels are not locked, it means that the insufficient deceleration is due to insufficient boost force, and in this case, after setting i-1° in step 48, this is set in step 4.
5 outputs T.

When this 1■i□, the solenoid valve 11 is 1-)2 as described above.
4 to boat 27 to remove the pressure in chamber 16 from the constant negative pressure in chamber 15. Therefore, the boost force is increased,
It is possible to bring the deceleration αR closer to the target αR.

By the way, when it is determined in step 4 that the wheels are locked, the boost force is not changed by executing steps 46 and 45, and the increase is indicated by B in FIG.

It is strictly prohibited to show any information. Note that even if the boost force is increased in this state, the insufficient deceleration αR cannot be resolved because the insufficient deceleration αR is caused by the locking of the wheels.

By prohibiting the boost force from increasing, it is possible to reduce the risk of the nine wheels continuing to be locked, and it is also possible to prevent the brake pedal from becoming abnormally large when the wheels are locked, resulting in poor brake pedal operation feeling. In addition, the brake force can be quickly lowered when the brake pedal is released, and a delay in brake release can be avoided.

FIGS. 8 and 7 show two other examples of the wheel lock determination subroutine. In the example shown in FIG. 6, if the brake pedal depression force is not changed or reduced, the wheels are not locked in step 62, that is, the vehicle deceleration αR increases in response to an increase in the brake pedal depression force. If so, it means that the vehicle is not locked, so if the vehicle deceleration αR does not change or decreases despite the step, that is, the increase in the brake pedal depression force, the wheels are locked in step 65. The judgment is T.

In the example shown in FIG. 7, in step 70, the deviation α1-α between the measured value α and the target value αi of vehicle deceleration is calculated, and in the next step 71, when this Oi value reaches the set value, in step 7a Determine lock, otherwise step 7
4, it is determined that the wheels are unlocked.

(Effects of the Invention) Thus, as described above, the brake booster of the present invention has a structure that prohibits the lift force from rising when the wheels are locked.
Compared to the conventional brake boost Pwt in which the brake boost force is raised when the wheels are locked without this prohibition, it is possible to reduce the number of continuations of the wheel lock state, and also when the wheels are in the four-wheel position, the brake pedal is depressed. It is possible to prevent the brake pedal from becoming abnormally large and make the operating feeling of the brake pedal frightening, and at the same time, the brake force can be quickly lowered when the brake pedal is released, and a delay in brake release can be avoided.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of the brake booster of the present invention; Fig. 2 is a system diagram showing an embodiment of the inventive device; Fig. 3 is a block diagram of the microcomputer used in the same side device; 5 and 5 are flowcharts showing the microcomputer's leg restraint program, and FIGS. 6 and 7 are flowcharts F1 and 7 respectively showing other two examples of the control program. FIG. Operation time chart FIG. 9 is an operation time chart of the conventional device when the wheels are locked. l...Brake pedal 2...Brake booster 8...Wheel lock detection means flaw...Push-stroke lift inhibiting means 10...Brake booster body 11...Magnetic valve 12... shell 141
．． , diaphragm 17... Butsch rod 1B
...Operating rod 20...Return spring 22...Capacity pressure source 2B...Constant high pressure source 28
．． 29... Valve body 80, 1llll...
Spring 82... Solenoid 83... Controller 84... Brake pedal depression force detection means 85...
Wheel speed detection means 36...Vehicle deceleration detection means Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 3 Figure 4

Claims (1)

[Claims] 1. In a brake booster that controls boost force so that the vehicle deceleration changes in a constant relationship with the depression force on the brake pedal, it is detected that the wheels are in a locked state. A brake booster comprising: a wheel lock detecting means; and a boost force increase inhibiting means for prohibiting an increase in the boost force while the wheels are locked.