DE19855696A1 - Antilock braking system for motor vehicle - Google Patents

Abstract

The antilock braking system has a brake pedal (10), a brake fluid reservoir (33), a main cylinder, a pedal sensor (20) detecting the pressure acting on the pedal, a brake per wheel, a normally open solenoid valve at the inlet to the brake controlling the flow of hydraulic pressure to the brake, a normally closed solenoid valve at the brake outlet, a suction pump (41) connected to the hydraulic line connecting the fluid reservoir to the brakes, a motor (40) driving the suction pump and an electronic controller. The electronic controller controls the operation of the motor and pump in accordance with the brake pedal force sensor signal.

Description

The present invention relates to a braking system for a vehicle, and in particular, to an anti-lock braking system for a vehicle that has a Braking can be done precisely using a slip ring motor and a suction pump instead of an amplifier.

A braking system is one of the most important safety systems in an automobile vehicle. The ability of the braking system to drive a vehicle to a safe, con Bringing a controlled stop is absolutely essential to avoid driving witness damage during an accident, personal injury and loss of life.  

Anti-lock braking systems have been developed in particular in recent years, that improve safe brake control on uneven or slippery roads can by the hydraulic pressure acting on the brake appropriately control is grown.

Fig. 1 shows a conventional anti-lock braking system connected to the hydraulic circuit's.

As shown in the drawing, the conventional anti-lock braking system includes the brakes 9 a, 9 b, 9 c and 9 d a brake pedal 1 , which is operated by the driver, an amplifier 2 for generating large braking forces using a pressure difference between the vacuum and the atmospheric pressure in cooperation with the pedal 1 , a liquid tank 4 for storing the fluid, and a master cylinder 3 receiving an increased force from the booster 2 to a hydraulic pressure using the fluid stored in the fluid tank 4 generate and transfer the hydraulic pressure to the brakes 9 a, 9 b, 9 c and 9 d.

Each of the brakes 9 a, 9 b, 9 c and 9 d is provided with a normally open so lenoid valve 5 and a normally closed solenoid valve 6 , in each case on the inlet and outlet sides.

Low-pressure accumulators 8 a are provided on each downward side of the normally closed solenoid valve 6 in order to temporarily store fluid released by the brakes 9 a, 9 b, 9 c and 9 d.

High-pressure accumulators 8 b are arranged on the downward side of the low-pressure accumulators 8 a, and pumps 7 a are arranged between the low-pressure and high-pressure accumulators 8 a and 8 b in order to fluid into the high-pressure accumulators 8 b to pump. The reference numerals 7 and 8 c, which have not yet been described above, each indicate a motor for driving the pumps 7 a, and openings.

In the conventional anti-lock braking system described above, the master cylinder 3 generates a hydraulic pressure depending on the amplifying force of the booster 2 when the brake pedal 1 is operated by the driver. The generated hydraulic pressure from the master cylinder 3 is guided to the brakes 9 a, 9 b, 9 c and 9 d via the corresponding normally open solenoid valve 5 in order to generate a braking force.

In addition, the wheel does not turn, but slips when an excessive braking force is applied to each wheel. At this time, this process is detected by a speed sensor (not shown), and a corresponding electrical signal is transmitted to a control area (not shown). The control section controls the normally closed solenoid valve 6 so that it is opened, whereby hydraulic pressure, which acts on the brakes 9 a, 9 b, 9 c and 9 d, is released to reduce the braking force. The released by the brakes 9 a, 9 b, 9 c and 9 d hydraulic pressure is temporarily stored in the low-pressure accumulators 8 a, and then raised again depending on the operation of the motor 7 by the pumps 7 a and then to the Master cylinder 3 or the normally open solenoid valve 5 leads back via the pump 7 , the high-pressure batteries 8 b and the openings 8 c being in a state where a radical pressure wave is reduced.

In the conventional anti-lock braking system described above, the system may be damaged by the hydraulic pressure in the case where the driver generates a braking force that is greater than a normal state because the booster 2 increases all the forces, thereby generating a high hydraulic pressure becomes. A high-performance motor is also required to operate the anti-lock braking system normally.

In addition, due to the size of the amplifier, it is difficult to internal the system to arrange half of an engine compartment of a vehicle.

The present invention was therefore made with the intentions that be above to solve written problems.

It is an object of the present invention to provide an anti-lock braking system for a To provide vehicle, which a braking process using an elec trical slip ring motor and a suction pump instead of an amplifier se can execute.

This object is achieved by the features of independent claim 1 solved, expedient embodiments by the features of Unteran sayings are described.

To achieve the above object, the present invention provides an antiblock Kier brake system for a vehicle, comprising a brake pedal, a fluid Tank for storing the fluid, a master cylinder for the formation of the hydrau pressure using the fluid contained in the fluid tank, a Pe dalsensor, which is arranged between the brake pedal and the master cylinder, to detect a brake pressure acting on the pedal, a brake, the one Exerts braking force on each wheel of the vehicle by receiving the hydraulic pressure, a normally open solenoid valve on the inlet side of the Brake is arranged to control the flow of hydraulic pressure, an in Normally closed solenoid valve on the outlet side of the brake is arranged to control the flow of hydraulic pressure, a suction pump, around the fluid in the fluid tank via the normally open solenoid valve to pump to the brake, with the suction pump on a hydraulic pressure line is arranged, which connects the fluid tank to the brake, a motor for on driven the suction pump, and an electronic control part for controlling a loading  drive of the motor and the suction pump in accordance with one of the Pedal sensor transmitted signal, the one applied to the brake pedal Brake pressure detected.

It is preferred that the motor be a slip ring motor.

The anti-lock braking system further includes a closed in the normal state Relief solenoid valve arranged on a hydraulic pressure line which ver the normally open solenoid valve with the fluid tank binds to direct a fluid released by the brake to the fluid tank, when braking operation is ended, a constant current valve that is on an off on the discharge side of the normally closed relief solenoid valve is arranged to prevent the fluid from flowing quickly, creating noise be suppressed, and a pressure detection sensor connected to a hydraulic system Pressure line is arranged, which connects the suction pump to the brake a brake pressure actually generated by the engine and the suction pump capture, and to transmit a corresponding signal to the elektroni control parts.

The electronic control section is designed around the engine and the suction pump to drive when the actual detected by the pressure detection sensor Brake pressure is less than the brake pressure and detected by the pedal sensor opens the normally closed relief solenoid valve when the actual brake pressure detected by the pressure detection sensor is higher than the brake pressure detected by the pedal sensor.

The anti-lock braking system can also be another, normally Stand closed solenoid valve include that on a hydraulic pressure line is arranged, the master cylinder with the open in the normal state So lenoid valve connects to a hydraulic formed inside the master cylinder transfer pressure to the brake when the motor or the suction pump is selected  rend the braking process has a malfunction, and a Pedalbetriebsre sponder, which is arranged on a hydraulic pressure line, the main cylinder which connects to the normally closed solenoid valve so that the Driver feels the braking process.

The accompanying drawings, which are incorporated in the description and a Forming part of the same, describe an embodiment of the invention and together with the description, serve to explain the principles of the invention dung:

Fig. 1 is a schematic view illustrating a conventional anti-lock braking system in connection with a hydraulic circuit thereof;

FIG. 2 is a schematic view illustrating an anti-lock brake system associated with a hydraulic circuit thereof according to a preferred embodiment of the present invention;

Fig. 3 is a block diagram of an electronic control part of an anti-lock brake system according to a preferred embodiment of the present invention;

Fig. 4 is a hydraulic circuit illustrating a normal Bremsbetriebszu stand of an anti-lock braking system according to a preferred embodiment of the present invention;

Fig. 5 is a hydraulic circuit illustrating a brake releasing operation of an antilock brake system according to a preferred embodiment of the present invention;

Fig. 6 is a hydraulic circuit illustrating a fail-safe state of an antilock brake system according to a preferred embodiment of the present invention;

Fig. 7 is a hydraulic circuit of a pressure reducing state of an antilock brake system according to a preferred form approximately exporting of the present invention;

Fig. 8 is a hydraulic circuit illustrating a pressure increase state of an antilock brake system according to a preferred embodiment of the present invention; and

Fig. 9 is a hydraulic circuit of an anti-lock brake system illustrating a state of non-changing a pressure in accordance with a Favor th embodiment of the present invention.

Reference will now be made in detail to the present preferred embodiment Form of the invention, an example of which is shown in the accompanying drawings is illustrated. Wherever possible, the same reference numerals will be used for the Drawings used to designate the same or similar components.

Figs. 2 and 3 each show a hydraulic circuit and an electro African control part of an anti-lock brake system according to a preferred embodiment of the present invention.

As shown in the drawings, the anti-lock braking system according to the present invention detects brakes 80 , 81 , 82 and 83 mounted on respective wheels to generate a braking force by hydraulic pressure, a brake pedal 10 operated by a driver in the normal state open solenoid valves 60 , which are arranged on each inlet side of the brakes 80 , 81 , 82 and 83 , and normally closed solenoid valves 61 , which are arranged on each outlet side of the brakes 80 , 81 , 82 and 83 .

The brake pedal 10 is connected to both a fluid tank 33 for storing the fluid and a master cylinder 30 for generating a hydraulic pressure which uses the fluid stored in the fluid tank 33 and gives the same to the brakes 80 , 81 , 82 and 83 . Pedal drive responders 32 and normally closed solenoid valves 31 are arranged on the outlet sides of the master cylinder 30 to connect the master cylinder 30 with normally open solenoid valves 60 along the hydraulic pressure line. The Pedalbe drive responder 32 and the normally closed solenoid valves 31 will be described in detail below.

A pedal sensor 20 is arranged between the brake pedal 10 and the master cylinder 30 , for detecting an actuation of the pedal 10 and for transmitting a corresponding signal to an electronic control part 100 (see FIG. 3). To the hydraulic pressure lines which are the fluid tank 33 to the brakes 80, 81, 82 and 83 connect, arranged suction pumps 41 to the fluid inside the fluid tank 33 to be pumped to the brakes 80, 81, 82 and 83, and a motor 40, which is connected to the electronic control part 100 to drive the suction pump 41 . A slip ring motor is preferably used as motor 40 , the torque and number of revolutions per minute can be controlled independently and has good responsiveness and durability.

Reference numerals 50 , 51 and 42 , which are not described above, indicate damping chambers, openings and control valves.

When the driver applies brake pressure to the brake pedal 10 , the brake sensor 20 detects this and transmits a corresponding signal to the electronic control part 100. The electronic control part 100 drives the slip ring motor 40 and the suction pumps 41 in accordance with the signal. As a result, a hydraulic pressure is generated by the fluid pumped from the fluid tank 33 by the suction pump 41 , whereupon the hydraulic pressure is changed to a linear hydraulic pressure as it passes through the damping chambers 50 and the openings 51 . The linear hydraulic pressure is applied to the brakes 80 , 81 , 82 and 83 via the normally open solenoid valves 60 .

In addition, on the hydraulic pressure lines that connect the fluid tank 33 to the normally open solenoid valves 60 , normally closed relief solenoid valves 70 are arranged. Constant flow valves 71 are arranged on the outlet side of the normally closed relief solenoid valves 70 to prevent the hydraulic pressure from flowing beyond a predetermined speed. That is, when the braking force is released, the normally closed relief solenoid valves 70 are opened so that the fluid that forms the hydraulic pressure is returned to the fluid chamber 33 . At this time, the constant flow valves 71 prevent the fluid from quickly returning to the fluid tank 33 , where noise is suppressed. This is described in detail below.

In addition, on the hydraulic pressure lines connecting the suction pumps 41 to the brakes 80 , 81 , 82 and 83 , pressure sensing sensors 90 for sensing the actual brake pressure generated by the slip ring motor 40 and the suction pumps 41 are arranged as well as for the transmission of a corresponding signal to the electronic control part 100. Therefore, the electronic control part 100 calculates a difference between the brake pressure exerted by the driver on the brake pedal 10 and the actual brake pressure generated by the slip ring motor 40 and the suction pumps 41 , and corrects it Operation of the slip ring motor 40 and the suction pump 41 in accordance with the difference value.

Referring to Fig. 3 of the pedal sensor 20 and the pressure are detected Sen sensors 90 to an input side of the electronic control part 100 is coupled, while the slip ring motor 40, the normally open Solenoidventi le 60, the normally closed solenoid valves 61 and 31, and in Normally closed relief solenoid valves 70 , which are controlled by sensors 90 controlled by pedal sensor 20 and pressure sensors, are coupled to an output side of electronic control part 100 .

Accordingly, when the driver applies brake pressure to the pedal 10 , this is detected by the pedal sensor 20 , then passed on to the electronic control part 100 to drive the slip ring motor 40 and the suction pump 41 in proportion to the braking force exerted by the driver. At this time, if the actual braking pressure generated by the slip ring motor 40 and the suction pump 41 , which is detected by the pressure sensing sensors 90 , deviates from the braking pressure applied by the driver, this is detected by the electronic control part 100 to operate the Slip ring motor 40 and the suction pumps 41 as well as the opening of the normally closed relief solenoid valves 70 .

A normal braking operation of the anti-lock braking system will be described below with reference to FIG. 4.

When the brake pedal 10 is operated by the driver to reduce the speed of the vehicle or to maintain a stopped state of the vehicle, hydraulic pressure is generated by the master cylinder 30 and then applied to the pedal operating responder 32 as well as to the normal state closed solenoid valves 31. At this point, the driver can feel braking operation by the pedal operation responders 32 . At the same time, the pedal sensor 20 detects the operation of the brake pedal 10 and transmits a corresponding signal to the electronic control part 100. The electronic control part 100 drives the slip ring motor 40 and the suction pumps 41 in accordance with the signal, whereby fluid is pumped from the fluid tank 33 becomes. The fluid receives a high energy level with a pulse wave when it passes through the suction pumps 41 and is converted into a linear hydraulic pressure when it passes through the damping chambers 50 and the opening 51 . The linear hydraulic pressure is given to the brakes 80 , 81 , 82 and 83 via the normally open solenoid valves 60 , whereby the braking process is realized.

At this point, the brake pressure actually generated by the slip ring motor 40 and the suction pumps 41 is also sensed by the pressure sensing sensors 90 and then transmitted to the electronic control part 100 so that it can be compared with the brake pressure applied to the pedal 10 , thereby providing a Difference between these is determined by the operation of the Schleifringmo gate 40 and the suction pumps 41 is corrected and the opening of the normally closed relief solenoid valves 70 is set. That is, the actual brake pressure generated by the slip ring motor 40 and the suction pumps 41 is compared with the brake pressure applied by the driver to the pedal 10 .

For example, if the actual brake pressure is less than the brake pressure applied by the driver, the electronic control part 100 operates the slip ring motor 40 and the suction pumps 41 , whereas if this is higher, the electronic control part 100 opens the normally closed relief solenoid valves 70 , so that the fluid is returned to the fluid tank 33 , thereby protecting the brake system from damage.

In addition, when the fluid is rapidly returned via the normally closed relief solenoid valves 70 , pressure can be generated. However, this is prevented by the constant flow valves 71 . That is, when the fluid flows through the constant flow valve 71 , rapid flow of the fluid is prevented, thereby suppressing noise.

A brake release operation of the anti-lock brake system according to the present invention will now be described with reference to FIG. 5.

When the driver reduces the brake pressure applied to the brake pedal 10 to reduce the braking force or stop braking, the brake pedal 10 tries to return to its home position and the fluid in the pedal operating responders 32 begins to flow to the fluid tank 33 via the main cylinder of FIG. 30 . At this point, the pedal sensor 20 detects the position and the speed of movement of the brake pedal 10 and then transmits a corre sponding signal to the electronic control unit 100. The electronic control unit 100 determines the brake pressure exerted by the driver, a pressure reduction speed and a complete brake pressure relief, opens then the normally closed relief solenoid valves 70 where the fluid returns to the fluid tank 33 via the normally opened solenoid valves 60 and the normally closed relief solenoid valves 70 to reduce the braking force. During this process, the pressure sensing sensor 90 senses the actual brake pressure. If the actual brake pressure is less than the brake pressure exerted by the driver, the electronic control part 100 closes the normally closed relief solenoid valves 70 and operates the slip ring motor 40 and the suction pumps 41 to increase the brake pressure to a level which Driver is desired.

In addition, the fluid returning in the fluid tank 33 through the normally closed relief solenoid valves 70 is also controlled by the constant flow valves 71 , thereby preventing noise.

The anti-lock brake system according to the present invention has a failure safety function. Fig. 6 is a hydraulic circuit from a fall-safety operation of the antilock brake system according to the present invention is illustrated.

As shown in the hydraulic circuit, the operation of the electronic control part 100 stops during the braking operation when the motor 40 or the suction pump 41 is not operated by a malfunction of the electronic control part 100 or other parts, which leads to an emergency, and becomes simultaneous the normally closed solenoid valves 31 are opened. In this state, the master cylinder 30 generates hydraulic pressure when the driver operates the brake pedal 10 and passes the hydraulic pressure to the brakes 80 , 81 , 82 and 83 via the normally closed solenoid valves 31 and the normally open solenoid valves 60 , thereby the braking process is realized. In addition, when the brake pedal 10 is released to end the braking operation, the fluid is returned to the fluid tank 10 via a path opposite to that through which the fluid is supplied to the brakes 80 , 81 , 82 and 83 to implement the braking process.

In addition, if an excessive braking force is applied to the wheels, or the braking force becomes higher than the frictional force between the wheels and the load surface due to a change in the conditions of the load surface, the wheels of the vehicle slip on the load surface. As a result, the vehicle loses its steering control or the braking distance increases. Therefore, the anti-lock brake system should be appropriately controlled in three states (a pressure increase state, a pressure decrease state and a pressure hold state) to prevent the above problems. This will be described in detail with reference to FIGS. 7 to 9.

Fig. 7 is a hydraulic circuit showing a pressure reduction state of the anti-lock braking system of the present invention.

When an excessive braking force acts on the wheels, or the braking force becomes higher than the frictional force between the wheels and the load surface due to a change in the conditions of the load surface, the electronic control part 100 opens the normally closed solenoid valves 61 to the fluid in the brakes 80 , 81 , 82 and 83 to the suction pumps 41 or the fluid tank 33 , thereby reducing the hydraulic pressure acting on the brakes 80 , 81 , 82 and 83 to keep the vehicle's wheels from slipping prevent.

Fig. 8 is a hydraulic circuit illustrating a pressure increase state of the on tiblockier brake system of the present invention.

If the hydraulic pressure acting on the brakes 80 , 81 , 82 and 83 is excessively reduced, or the vehicle is moving on a road that has a high coefficient of friction, the braking efficiency will be reduced because the frictional force between the wheels and the road is higher than the braking force applied to the brakes 80 , 81 , 82 and 83 .

Therefore, the electronic control part 100 drives the slip ring motor 40 as well as the suction pumps 40 in order to increase the brake pressure acting on the brakes 80 , 81 , 82 and 83 . As a result, fluid is pumped into the suction tank 41 in the fluid tank 33 . At this time, the fluid supplied to the suction pumps 41 receives pressure with a pulse wave, but changes to a linear hydraulic pressure when it passes through the damping chambers 50 and the openings 51 . The linear hydraulic pressure is supplied to the brakes 80 , 81 , 82 and 83 via the normally open solenoid valves 60 , whereby the brake pressure is increased. If, in addition, the hydraulic pressure is again excessively increased during this Druckzu acquisition state, the pressure sensing sensor 90 detects this and transmits a corresponding signal to the electronic control part 100. The electronic control part 100 then opens the normally closed relief solenoid valves 70 to the hy to reduce drastic pressure, which protects the braking system from damage. The flow of the fluid passing through the normally closed relief solenoid valves 70 is controlled by the constant flow valve 71 so that noises generated by the rapid flow of the fluid can be suppressed.

In addition, if the hydraulic pressure acting on the brakes 80 , 81 , 82 and 83 reaches an optimal level at which an optimal braking force is generated, the hydraulic pressure should not be changed, ie the brake pressure should be maintained.

Fig. 9 is a hydraulic circuit illustrating a pressure holding state of the anti-lock braking system of the present invention.

To maintain the brake pressure acting on brakes 80 , 81 , 82 and 83 , the normally open solenoid valves 60 are closed to prevent the fluid from transmitting to brakes 80 , 81 , 82 and 83 . During this pressure-holding state, the suction pumps 41 are operated when a wheel is present which requires an increased braking pressure in order to supply the hydraulic pressure to the brakes of the wheel. At this point, the hydraulic pressure is increased excessively, the pressure sensing sensors 90 of this erfas sen and 100 übertra gen a corresponding signal to the electronic control units. The electronic control portion 100 opens the normally closed relief solenoid valves 70 to the hydraulic pressure to reduce where the brake system protects against damage.

Although preferred embodiments of the present invention above in De tail, it is obvious that variations and / or modes fications of the basic concept of the invention can take place arise for the expert, these being the scope of the present ing invention, as defined in the appended claims.

Claims (8)

1. An anti-lock braking system for a vehicle, comprising:
a brake pedal ( 10 );
a fluid tank ( 33 ) for storing fluid;
a master cylinder ( 30 ) for forming hydraulic pressure using the fluid contained in the fluid tank ( 33 );
a pedal sensor ( 20 ), which is arranged between the brake pedal ( 10 ) and the master cylinder ( 30 ), for detecting a brake pressure acting on the pedal;
a brake ( 80 , 81 , 82 , 83 ) which applies a braking force to each wheel of the vehicle by receiving hydraulic pressure;
a normally open solenoid valve ( 60 ) disposed on the inlet side of the brake for controlling the flow of hydraulic pressure;
a normally closed solenoid valve ( 61 ), which is arranged on the outlet side of the brake for controlling the flow of hydraulic pressure;
a suction pump ( 41 ) for pumping the fluid within the fluid tank ( 33 ) to the brake ( 80 , 81 , 82 , 83 ) via the normally open solenoid valve ( 60 ), the suction pump ( 41 ) being arranged on a hydraulic pressure line, which binds the fluid tank ( 33 ) to the brake ( 80 , 81 , 82 , 83 );
a motor ( 40 ) for driving the suction pump ( 41 ); and
an electronic control part ( 100 ) for controlling the operation of the engine ( 40 ) and the suction pump ( 41 ) in accordance with a signal transmitted by the pedal sensor ( 20 ) which detects a brake pressure applied to the brake pedal ( 10 ). 2. An anti-lock braking system according to claim 1, wherein the motor ( 40 ) is a slip ring motor. 3. An anti-lock brake system according to claim 1, further comprising a normally closed relief solenoid valve ( 70 ) on a hy draulic pressure line which connects the normally open solenoid valve ( 60 ) to the fluid tank ( 33 ) to the brake ( 80 , 81 , 82 , 83 ) direct the released fluid to the fluid tank ( 33 ) when the braking process is released. 4. An anti-lock braking system according to claim 3, further comprising a Kon constant flow valve ( 71 ) which is arranged on an outlet side of the normally closed relief solenoid valve ( 70 ) to prevent the fluid from flowing quickly, thereby Noises are suppressed. 5. An anti-lock brake system according to claim 1, further comprising a pressure sensing sensor ( 90 ) disposed on a hydraulic pressure line connecting the suction pump ( 41 ) to the brake ( 80 , 81 , 82 , 83 ) to the actual brake pressure generated by the motor ( 40 ) and the suction pump ( 41 ) and to transmit a signal corresponding to the detected actual brake pressure to the electronic control part ( 100 ). 6. An anti-lock brake system according to claim 5, wherein the electronic control part ( 100 ) is designed to drive the motor ( 40 ) and the suction pump ( 41 ) when the actual brake pressure detected by the brake pressure detecting sensor ( 90 ) is lower is to be opened as the brake pressure detected by the pedal sensor ( 20 ) and the normally closed relief solenoid valve when the actual brake pressure detected by the brake pressure detecting sensor ( 90 ) is higher than the brake pressure detected by the pedal sensor ( 20 ). 7. The anti-lock braking system of claim 1, further comprising a further normally closed solenoid valve disposed on a hydraulic pressure line connecting the master cylinder ( 30 ) to the normally open solenoid valve ( 60 ) around that within the master cylinder ( 30 ) formed hydraulic pressure to the brake se ( 80 , 81 , 82 , 83 ) to transfer when the motor ( 40 ) or the suction pump ( 41 ) malfunctions during the braking process. 8. An anti-lock brake system according to claim 7, further comprising a pedal operating responder ( 32 ) which is arranged on a hydraulic pressure line which connects the master cylinder ( 30 ) with the normally closed ge solenoid valve ( 60 ) to give the driver a brake feel convey.