KR100372240B1 - Apparatus for controlling oil pressure of a brake system comprising a Middle pressure accumulate(MPA) - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a brake hydraulic pressure control device having a medium pressure accumulator for easily detecting in an indirect manner an accumulating state of a brake fluid flowing into a medium pressure accumulator.

To this end, the present invention features a switching unit 22 for easily detecting the brake hydraulic pressure in an indirect manner without using an expensive liquid level sensor for directly detecting the brake hydraulic pressure of the medium pressure accumulator (MPA).

Therefore, the present invention can prevent the drawback of weakening durability by performing the accumulating operation for the medium pressure accumulator unnecessary as before. In addition, the present invention can be easily detected by the switching structure has the effect of reducing the manufacturing cost and improve the workability.

Description

Apparatus for controlling oil pressure of a brake system comprising a Middle pressure accumulate (MPA)}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake hydraulic pressure control device having a medium pressure accumulator, and more particularly to a brake hydraulic pressure control device having a medium pressure accumulator for easily detecting the brake hydraulic pressure flowing into the medium pressure accumulator in an indirect manner.

In recent years, the electronic control unit (ECU) mounted on a vehicle performs ABS control (ABS), traction control system (TCS), and vehicle dynamic control (VDC) to perform driving stability of the vehicle. Overheating and braking performance have been proposed.

In such a vehicle, the brake hydraulic pressure generated in the master cylinder is supplied to the wheel cylinder of the wheel by the normal brake operation by stepping on the brake pedal, so that the braking force is exerted, and during the braking operation, the electronic control device uses the ABS according to the slip ratio calculated from the vehicle speed. Braking is started, and the ABS control operation is performed by increasing or decreasing the brake hydraulic pressure supplied to the wheel cylinder of the wheel or maintaining the optimum state.

When slippage occurs due to excessive engine torque or road surface conditions during sudden start and sudden braking of the vehicle, the driving state of the vehicle is applied by applying an appropriate brake hydraulic pressure to the wheel cylinder without pressing the brake pedal so that the driving torque corresponding to the road condition is maintained. The traction control operation to be controlled is performed.

In addition, when the vehicle is in a slippery road state when driving at high speeds or turning, or in the case of excessive yaw moments, the vehicle may not be adjusted according to the driver's intention and in the worst case, the body may spin. By supplying the appropriate brake hydraulic pressure to perform the vehicle attitude control operation to maintain the stable driving state of the vehicle. For example, if the driver excessively bends the steering wheel and exceeds the preset steering angle, the vehicle may be moved inward in the direction in which the vehicle is turned, and in the direction in which the vehicle is turned due to the friction conditions of the road surface. Under steering occurs. At this time, the electronic control device presses the brake fluid pressure on the outer wheel in the direction in which the vehicle is turning in the oversteering condition, and presses the brake fluid pressure on the inner wheel in the understeering condition so that the vehicle proceeds stably according to the driver's steering intention. Done.

As described above, in order to smoothly perform ABS control operation, traction control and vehicle position control, a middle pressure accumulate (MPA) is used in addition to the low pressure accumulator (LPA) and the high pressure accumulator (HPA) used in the conventional ABS system. Will be provided.

However, in the prior art, since the pressure storing operation of the medium pressure accumulator was performed by the electronic control device during vehicle startup, the pressure storing operation was periodically performed every several hours in consideration of leakage of the brake fluid. Even when a proper amount of the brake fluid flowed in, the accumulating operation was performed unnecessarily, resulting in a shortening of the life of the component due to weakened durability.

In view of this, in the related art, a method of performing a pressure storing operation by providing a sensor for detecting the accumulated pressure of a brake fluid in a medium pressure accumulator (MPA) has been proposed. For example, the medium pressure accumulator 1 shown in FIG. 1 is provided with a piston 1b inside the cylinder 1a, and the compression spring 1c elastically supports the piston 1b, and the upper side of the cylinder 1a. The flow path 1e is formed in the. A plug 1d having an air hole 1h formed therein is provided at the opening of the cylinder 1a, and a snap ring 1f is provided in the gap between the plug 1d and the cylinder 1a. An annular groove 1g is formed to seat 1f). Then, the liquid level detecting sensor 2 for detecting the amount of brake fluid flowing through the flow path (1e) is provided in the cylinder (1a).

If it is determined that the amount of brake fluid sensed by the liquid level sensor 2 is insufficient, the electronic controller performs an accumulator operation so that the appropriate amount of brake fluid is maintained in the medium pressure accumulator 1. That is, when the brake hydraulic pressure flowing through the flow path (1e) is greater than the elastic force of the compression spring (1c) is stored in the cylinder (1a) while pressing the piston (1b) downward. At this time, the liquid level sensor 2 detects the brake hydraulic pressure flowing into the cylinder (1a). On the other hand, when the brake fluid pressure is supplied to the wheel cylinder of the vehicle, the brake fluid stored in the cylinder 1a is guided out of the flow path 1e and the piston 1b is moved upward by the elastic force of the compression spring 1c. At this time, the liquid level detection sensor 2 detects the brake fluid pressure exiting.

However, in the related art, precise work is required to seal the gap portion so that the brake fluid does not leak through the gap of the liquid level sensor installed in the cylinder, thereby reducing workability, and expensive liquid level sensing directly detecting the brake liquid amount. The constraints on the use of sensors have led to increased manufacturing costs.

The present invention has been made to solve the above problems, an object of the present invention is to provide a brake hydraulic pressure control device having a medium pressure accumulator to easily detect the pressure accumulation state of the brake fluid flowing into the medium pressure accumulator in an indirect manner In providing.

1 is a cross-sectional view of a medium pressure accumulator showing a state in which a conventional liquid level sensor is installed;

2 is a block diagram of a brake hydraulic pressure control device having a medium pressure accumulator according to the present invention;

3A to 3C are cross-sectional views of a medium pressure accumulator applied to the present invention;

4A is a hydraulic circuit diagram illustrating an accumulator operation for a medium pressure accumulator;

4B is a hydraulic circuit diagram illustrating a state in which vehicle attitude control is performed.

Explanation of symbols on the main parts of the drawings

20: operation state detection unit 21: braking state detection unit

22: switching unit 23: control unit

24: solenoid valve driving unit 25: motor driving unit

An object of the present invention as described above consists of a variety of sensors mounted on the vehicle running state detection unit for detecting the driving state, braking state detection unit for detecting whether the braking of the vehicle, the driving state detection unit and the braking state detection unit A brake hydraulic pressure control device for controlling a brake hydraulic pressure supplied to a wheel cylinder of a vehicle by providing a medium pressure accumulator on a hydraulic circuit to perform ABS control, traction control, and vehicle attitude control according to detected driving information and braking information. A switching unit for turning on and off depending on the brake hydraulic pressure of the medium pressure accumulator; When the brake hydraulic pressure of the medium pressure accumulator reaches a preset lower limit value and a predetermined signal is output from the switching unit, it is determined as a start condition of the accumulation operation of the medium pressure accumulator and controls the operation of accumulating the appropriate amount of brake fluid in the medium pressure accumulator. Control unit; A motor driving unit for driving a motor provided on the hydraulic circuit under the control of the controller so as to pump the brake fluid on the hydraulic circuit and accumulate the pressure in the medium pressure accumulator; And a solenoid valve driver for opening or closing the solenoid valve provided on the hydraulic circuit under the control of the controller so that the brake fluid pumped by the driving of the motor is guided to the medium pressure accumulator via the hydraulic circuit.

The switching unit according to the present invention includes a piston reciprocating according to the brake hydraulic pressure flowing into the cylinder of the medium pressure accumulator, a piston pivot attached to one side of the piston, and a leaf spring switched by the movement of the piston pivot. And a support for supporting one side of the leaf spring and having a power terminal formed therein, and a contact formed on the leaf spring and the support, respectively.

In addition, the switching unit according to the present invention, the piston reciprocating according to the brake hydraulic pressure flowing into the cylinder of the medium pressure accumulator, a piston pivot attached to one side of the piston, a support formed with a power terminal, and the piston pivot And characterized in that it comprises a contact formed on each of the support.

In addition, the switching unit according to the present invention, the piston reciprocating according to the brake hydraulic pressure flowing into the cylinder of the medium pressure accumulator, a piston pivot for transmitting a brake hydraulic pressure applied to the piston separated from the piston, the piston pivot It is attached to the upper surface and characterized in that it comprises a piezoelectric element for converting the brake hydraulic pressure transmitted through the piston pivot into an electrical signal, and a support formed with a power terminal for outputting the signal converted by the piezoelectric element.

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

2 is a block diagram of a brake hydraulic pressure control device having a medium pressure accumulator according to the present invention. As shown, the present invention includes a driving state detecting unit 20 and a braking state detecting unit 21 for detecting a driving state and a braking state of the vehicle. The driving state detection unit 20 includes various sensors mounted on a vehicle, and includes a sensor 1 for detecting a wheel speed, a sensor 2 for detecting a steering angle, and the like. The signal is output to the controller 23. The braking state detector 21 may detect a braking state when the vehicle is decelerated or stopped. The braking state detector 21 may be implemented as a brake switch that is turned on or off or a treble sensor that detects displacement of the brake pedal according to whether the brake pedal is operated. .

The present invention is directed to a hydraulic circuit provided with a medium pressure accumulator (MPA) for performing ABS control, traction control and vehicle attitude control, and the accumulator operation for the medium pressure accumulator (MPA) is the driving state detection unit (20). And a controller 23 for receiving the driving information and the braking information detected through the braking state detection unit 21. The solenoid valve driving unit 24 for opening or closing the plurality of solenoid valves V1, V2,-, Vn provided on the hydraulic circuit under the control of the control unit 23, and by the control of the control unit 23 The motor drive part 25 which drives the motor M provided on the hydraulic circuit is provided.

In addition, the present invention is characterized in that it comprises a switching unit 22 for easily detecting the brake pressure in an indirect manner without using an expensive liquid level detection sensor that directly detects the brake pressure of the medium pressure accumulator (MPA), the switching unit When the brake fluid flowing into the medium pressure accumulator MPA decreases to a predetermined lower limit value, the sensor 22 outputs a detection signal according to the control unit 23. At this time, the control unit 23 starts the accumulating operation of the medium pressure accumulator MPA by the detection signal from the switching unit 22.

3A to 3C illustrate the switching unit 22 installed in the medium pressure accumulator 11 to indirectly detect the brake hydraulic pressure, which will be described in detail.

First, the medium pressure accumulator 11 illustrated in FIG. 3A includes a cylinder 11a, a piston 11b for reciprocating the inside of the cylinder 11a, and a compression spring 11c for elastically supporting the piston 11b. It is provided, the flow path (11e) is formed on the upper portion of the cylinder (11a). In addition, a plug 11d having an air hole 11h formed in the lower portion of the cylinder 11a is provided, and a snap ring 11f is formed in the gap between the inner surface of the cylinder 1a and the plug 1d outside of the annular groove 11g. Is seated on. In addition, the switching unit 22 includes a piston pivot 22a attached to the bottom surface of the piston 11b, a leaf spring 22c switched by the movement of the piston pivot 22a, and the leaf spring 22c. A support 22b having one side of the power supply terminal 22e formed thereon and a contact 22d formed at the leaf spring 22c and the support 22b, respectively.

When a proper amount of brake fluid is accumulated in the cylinder 11a of the medium pressure accumulator 11, the piston 11b moves downward as shown in FIG. 3A, and thus, the piston pivot 22a is one side of the support 22b. The contact 22d is dropped by pressing the connected leaf spring 22c. At this time, the power supply terminal 22e of the support 22b is not energized so that an off signal is input to the controller 23.

When the brake fluid accumulated in the medium pressure accumulator 11 exits and this state is left, the brake fluid pressure is reduced to reach the lower limit value. At this time, the piston 11b is moved upward by the compression spring 11c, and the piston pivot ( 22a) move together. Accordingly, the contact spring 22d formed at the leaf spring 22c and the support 22b is attached, and the power supply terminal 22e is energized so that an on-signal is input to the controller 23.

Meanwhile, the medium pressure accumulator 11 illustrated in FIG. 3B is the same as the component illustrated in FIG. 3A, and the switching unit 22 contacts the piston pivot 22a instead of the leaf spring 22c illustrated in FIG. 3A. 22f is formed. Operation for this switching section 22 is similar to that of FIG. 3A. That is, when a proper amount of brake fluid is accumulated in the cylinder 11a of the medium pressure accumulator 11, the piston pivot 22a attached to the piston 11b moves downward, and thus the contact point formed in the piston pivot 22a. Since 22f of 22f and the contact 22d of the support 22b are not energized, off signal is input to the said control part 23. As shown in FIG. On the other hand, when the brake fluid accumulated in the medium pressure accumulator 11 exits and the brake hydraulic pressure reaches the lower limit, the piston pivot 22a moves upward by the compression spring 11c. Since the contact 22d formed at the contact 22f and the support 22b is attached, the power supply terminal 22e is energized so that the on signal is input to the control unit 23.

Meanwhile, the medium pressure accumulator 11 illustrated in FIG. 3C is the same as the components illustrated in FIGS. 3A and 3B, and the switching unit 22 senses the brake hydraulic pressure using the piezoelectric element 22g. That is, when a proper amount of brake fluid is accumulated in the cylinder 11a of the medium pressure accumulator 11, the piston 11b moves downward to contact the upper end of the piston pivot 22a, and the piston pivot 22a. Since it is attached to the upper surface, a force corresponding to the brake hydraulic pressure transmitted through the piston pivot 22a is transmitted to the piezoelectric element 22g. Accordingly, the piezoelectric element 22g converts the pressure into an electrical signal and outputs an off signal to the controller 23 through the power supply terminal 22e. On the other hand, when the brake fluid accumulated in the medium pressure accumulator 11 exits and the brake hydraulic pressure reaches the lower limit value, the piston 11b moves upward by the compression spring 11c to be separated from the piston pivot 22a. Accordingly, when the force transmitted through the piston pivot 22a is lost, the piezoelectric element 22g outputs an on signal to the controller 23 through the power supply terminal 22e.

As described above, the control unit 23 controls the solenoid valve driver 24 and the motor driver 25 when a detection signal input from the switching unit 22, that is, an on signal from the power terminal 22e is input. The pressure accumulating operation is performed on the medium pressure accumulator 11. This will be described with reference to FIG. 4A.

In other words, the control unit 23 controls the solenoid valve driving unit 24 during the pressure storage operation, so that the inlet side solenoid valves 4a, 4b, 4c, and 4d of the wheel cylinders 7a, 7b, 7c, and 7d and the master are controlled. The solenoid valves 14a and 14b on the cylinder 3 side are closed to block communication between the master cylinder 3 and the wheel cylinders 7a, 7b, 7c, and 7d, while controlling the motor driving unit 25 to control the motor ( 8) is driven and pumped by the hydraulic pumps 9a and 9b by the power of the motor 8 to suck and discharge the brake fluid in the master cylinder 3 through the electric shuttle valves 16a and 16b. Accordingly, the brake hydraulic pressure of the hydraulic line is closed at the inlet side solenoid valves 4a, 4b, 4c, and 4d of the wheel cylinders 7a, 7b, 7c, and 7d and the solenoid valves 14a and 14b on the master cylinder 3 side. Since the pressure rises, the brake fluid pressure is increased by more than the predetermined pressure, and the pressure is accumulated by the medium pressure accumulator 11 through the relief valves 13a and 13b on the bypass flow path.

Thereafter, a proper amount of brake fluid is accumulated in the medium pressure accumulator 11, and the pressure storing operation is continuously performed until a detection signal, that is, an off signal is input from the switching unit 22. On the other hand, when the brake fluid is excessively accumulated in the intermediate pressure accumulator 11 by an appropriate amount or more during the accumulator operation, the brake fluid discharged from the hydraulic pumps 9a and 9b is transferred to the master cylinder 3 through the relief valves 15a and 15b. By reflux, the brake system is not overwhelmed.

In the state where the brake fluid of the appropriate amount is accumulated in the medium pressure accumulator 11 as described above, the controller 23 supplies the driving information and the braking information detected by the driving state detector 20 and the braking state detector 21. Accordingly, the brake hydraulic pressure supplied to the wheel cylinder of the vehicle is controlled to perform ABS control, traction control, and vehicle attitude control.

For example, the hydraulic circuit diagram of FIG. 4B is a vehicle posture for controlling the brake hydraulic pressure applied to the wheel cylinders of the wheels in which the vehicle is inwardly turned in the turning direction when the oversteering condition corresponds to the information obtained from various sensors of the vehicle. In this case, the inner wheels in the vehicle turning direction are RL and FL and the outer wheels are FR and RR.

First, during vehicle attitude control, the controller 23 controls the solenoid driving unit 24 to close the solenoid valves 14a and 14b and the electric shuttle valves 16a and 16b regardless of the driver's braking intention, thereby closing the master cylinder ( 3) The communication between the wheel cylinders 7a, 7b, 7c, and 7d is interrupted, and the solenoid valves 12a and 12b connected to the medium pressure accumulator 11 are opened to open the medium pressure accumulator 11 and the hydraulic pumps 9a and 9b. Connect the suction port of. At the same time, the control unit 23 controls the motor driving unit 25 to drive the motor 8 and to drive the hydraulic pumps 9a and 9b by the power of the motor 8 to the medium pressure accumulators 9a and 9b. The pressurized brake fluid is linearly converted through the high pressure accumulators 10a and 10b and then supplied to the wheel cylinders 7a, 7b, 7c and 7d via the solenoid valves 4a, 4b, 4c and 4d. .

The control unit 23 closes the solenoid valves 4b and 4d on the inner wheels RL and FL in the vehicle turning direction to block the inflow of the brake hydraulic pressure to the wheel cylinders 7b and 7d, and the outer wheel. The solenoid valves 4a and 4c on the (FR, RR) side are opened to pressurize the brake hydraulic pressure to flow into the wheel cylinders 7a and 7c. As a result, rotation moments acting opposite to the direction in which the vehicle turns, are generated in the outer wheels FR and RR, and the rotation moments are prevented from being directed to the inside of the vehicle. Therefore, the vehicle proceeds stably according to the driver's steering intention.

As described above, the present invention includes a switching unit installed to detect the brake hydraulic pressure in an indirect manner in the medium pressure accumulator, thereby making it possible to prevent the disadvantage of weakening durability by unnecessarily performing the pressure storing operation for the medium pressure accumulator. In addition, the present invention has the effect that it is possible to reduce the manufacturing cost and improve the workability because the precise processing operation is required and can be easily detected by a switching structure instead of using an expensive liquid level sensor.

Claims (4)

It is composed of various sensors mounted on the vehicle to detect the driving state, the braking state detection unit to detect whether the vehicle is braking, the driving state detection unit and the braking state detection unit detected through the driving state detection unit and the braking state detection unit. A brake hydraulic pressure control device for controlling a brake hydraulic pressure supplied to a wheel cylinder of a vehicle by providing a medium pressure accumulator on a hydraulic circuit to perform ABS control, traction control, and vehicle position control. A switching unit turned on or off according to the brake hydraulic pressure of the medium pressure accumulator; When the brake hydraulic pressure of the medium pressure accumulator reaches a preset lower limit value and a predetermined signal is output from the switching unit, it is determined as a start condition of the accumulation operation of the medium pressure accumulator and controls the operation of accumulating the appropriate amount of brake fluid in the medium pressure accumulator. Control unit; A motor driving unit for driving a motor provided on the hydraulic circuit under the control of the controller so as to pump the brake fluid on the hydraulic circuit and accumulate the pressure in the medium pressure accumulator; And And a solenoid valve driver for opening or closing the solenoid valve provided on the hydraulic circuit under the control of the controller so that the brake fluid pumped by the driving of the motor is guided to the medium pressure accumulator via the hydraulic circuit. Brake hydraulic pressure control device with an accumulator. The plate of claim 1, wherein the switching unit is configured to reciprocate according to a brake hydraulic pressure flowing into a cylinder of the medium pressure accumulator, a piston pivot attached to one side of the piston, and a plate switched by movement of the piston pivot. A brake hydraulic pressure control device including a spring, a support for supporting one side of the leaf spring, the power supply terminal is formed, and a contact formed in the leaf spring and the support, respectively. The piston of claim 1, wherein the switching unit includes a piston reciprocating according to a brake hydraulic pressure flowing into the cylinder of the medium pressure accumulator, a piston pivot attached to one side of the piston, a support formed with a power terminal, and the piston pivot. And a medium pressure accumulator, the brake hydraulic pressure control device comprising a contact point formed in the support. The piston of claim 1, wherein the switching unit includes a piston reciprocating according to a brake hydraulic pressure flowing into a cylinder of the medium pressure accumulator, a piston pivot which is separated from the piston and transmits a brake hydraulic pressure applied to the piston, and the piston pivot. A medium pressure device comprising: a piezoelectric element attached to the upper surface and configured to convert a brake hydraulic pressure transmitted through the piston pivot into an electrical signal, and a power supply terminal configured to output a signal converted by the piezoelectric element. Brake hydraulic pressure control device with an accumulator.