KR20030006552A - Anti-lock brake system - Google Patents

Abstract

PURPOSE: An anti-lock brake system is provided to reduce noise by damping periodic pulsation of oil pressure efficiently through a bypass unit and a high-pressure accumulator, and to improve the reliability by preventing vibration of a brake pedal. CONSTITUTION: A bypass unit(50) of an anti-lock brake system is composed of an installation bore(51) formed in a bore(31a) of a modulator block(31), and connected to a pressure chamber(43); a check valve(52) installed in the installation bore, and opened in increasing pressure over the reference value; and a hydraulic bypass line connected to the lower part of the installation bore and a hydraulic line of a low pressure accumulator to guide hydraulic pressure downstream in pumps. Noise and vibration are prevented by reducing pulsation of oil pressure efficiently with the bypass unit.

Description

Anti-lock brake system

The present invention relates to an antilock brake system, and more particularly to an antilock brake system having a pump for forcibly pumping oil temporarily stored in the low pressure accumulator to the high pressure accumulator.

In general, the anti-lock brake system (Anti-lock Brake System) is to obtain a stable braking force by effectively preventing the slip phenomenon of the tire sliding on the road surface during braking action, the configuration thereof is as shown in FIG.

Referring to FIG. 1, a conventional anti-lock brake system 10 temporarily stops oil and a plurality of solenoid valves 11A and 11B for controlling braking hydraulic pressure transmitted to a hydraulic brake 3 mounted on a wheel of a vehicle. A pair of low pressure accumulators 12 and high pressure accumulators 15 to be stored, a motor 13 and a pump 14 for forcibly pumping oil temporarily stored in the low pressure accumulator 12, and a solenoid valve 11A ( 11B) and an ECU (not shown) for controlling the driving of the motor 13.

The solenoid valve is divided into NO type solenoid valve 11A disposed on the upstream side of the hydraulic brake 3 and NC type solenoid valve 11B disposed on the downstream side, and their opening and closing operations are wheel sensors (not shown). It is controlled by the ECU that detects the vehicle speed.

In addition, the low pressure accumulator 12 is independently provided on the downstream side of the NC type solenoid valve 11B so that oil escaping from the hydraulic brake 3 side is temporarily stored in the decompression mode, and the high pressure accumulator 15 is a kind of damping chamber. It is arranged to be connected in series with the low pressure accumulator 12, the orifice 16 is provided in the outlet portion.

In addition, a pair of pumps 14 driven by one motor 13 is disposed between the low pressure accumulator 12 and the high pressure accumulator 15, and pressurizes the oil in the low pressure accumulator 12 to pressurize the high pressure accumulator 15. Will be pumped to the side.

Meanwhile, the low pressure accumulator 12, the pump 14, the high pressure accumulator 15, and the plurality of solenoid valves 11A and 11B are provided in a modulator block (not shown) made of aluminum.

In a vehicle equipped with the conventional anti-lock brake system configured as described above, when the driver presses the brake pedal 1, the boosting force is formed in the power supply device 2, thereby forming the braking hydraulic pressure in the master cylinder 4. This braking hydraulic pressure is transmitted to each hydraulic brake 3 through the NO solenoid valve 11A, and a braking force is generated.

On the other hand, when excessive braking pressure is transmitted or road surface is slippery, road slippage occurs. The ECU detects slippage based on a signal input from a wheel sensor.

If a slip phenomenon is detected, the ECU lowers the braking pressure by opening the NC solenoid valve 11B. At this time, the oil escaping from the hydraulic brake 3 through the NC type solenoid valve 11B moves to the low pressure accumulator 12 and is stored for a while. When the motor 13 is driven, the oil in the low pressure accumulator 12 is elevated to the high pressure accumulator 15 by increasing the pressure again through the pump 14, and the master cylinder 4 or the NO solenoid valve 11A. Is supplied again.

At this time, the high-pressure accumulator 15 is configured to have a chamber in the modulator block, so that oil pumped at high pressure through the pump 14 is temporarily stored, thereby reducing pressure pulsation. In addition, the pressure pulsation of the oil discharged by the orifice 16 disposed on the outlet side of the high pressure accumulator 15 is further reduced and supplied to the hydraulic line.

However, in the conventional anti-lock brake system, the sudden pressure pulsation generated by the driving of the pump 14 is reduced by the orifice 16 disposed in the high pressure accumulator 15. The orifice 16 simply reduces the opening degree of the flow and is irregular. Reducing the pressure pulsation of the oil has a limit to significantly reduce the pressure pulsation.

Accordingly, the pressure pulsation peak of the pressurized oil remains in the hydraulic line of the anti-lock brake system 10 and acts as a cause of operation noise, and the pressure pulsation is transmitted to the brake pedal 1 side through the master cylinder 4. There is a problem that causes anxiety to the driver.

The present invention is to solve such a problem, an object of the present invention is to configure a separate bypass means in the pump to an anti-lock brake system that can more efficiently reduce the pressure pulsation of the oil periodically generated when the pump is driven To provide.

1 is a hydraulic system diagram of a conventional anti-lock brake system.

2 is a hydraulic system diagram of an anti-lock brake system for a vehicle according to the present invention.

3 is a cross-sectional view showing the internal structure of the pump according to the present invention.

Figure 4 is an enlarged view of portion "A" of Figure 3, showing a bypass means according to the present invention.

5 shows an operating state of the bypass means according to the present invention.

* Description of the symbols for the main parts of the drawings *

31. Modulator block 31a Bore 31b Suction port

31c.Discharge port 40L, 40R .. Pump 41. Piston

42. Inlet valve 43. Pressure chamber 44. Plug

45. Outlet valve 50. Bypass means 51. Mounting bore

52..Check valve 53.Bypass hydraulic line

The present invention for achieving this object is;

A pump installed in the bore formed in the modulator block and forcibly pumping the oil in the low pressure accumulator and forcibly pumping it to the high pressure accumulator during a pressure-induced braking or a pressure holding braking action,

The pump is installed in the bore to reciprocate and has a piston having a suction flow path therein, an inlet valve provided at the tip of the piston to open and close the suction flow path, and a pressurizing chamber formed between the piston tip and the open end of the bore. And an anti-lock brake system with a valve housing with a built-in outlet valve,

A mounting bore provided in communication with the pressure chamber in the bore of the modulator block, a check valve installed in the mounting bore and opened when the pressure chamber rises above a predetermined pressure, and one end in communication with the bottom of the mounting bore and the other end of the hydraulic line on the low pressure accumulator side. It is characterized in that it is provided with a bypass means including a bypass hydraulic line connected to the and guides a portion of the hydraulic pressure to the downstream side of the pump when opening the check valve.

In addition, the check valve is press-fitted to the mounting bore and the valve housing having an orifice formed therein, a sphere embedded in the valve housing to open and close the orifice, an elastic member elastically supporting the sphere, and a valve housing to prevent the elastic member from being separated. It is installed at the rear end of the oil passage is characterized in that it comprises a stopper formed.

According to such a structure, when the oil pressure pulsation of a pressurization chamber rises more than predetermined pressure, a check valve will open and a part of oil will be guided downstream of a pump, and a pressure pulsation can be reduced primarily.

Hereinafter, one preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. Briefly the accompanying drawings, Figure 2 is a hydraulic system showing an anti-lock brake system according to the present invention, Figures 3 and 4 are sectional views showing the internal structure and bypass means of the pump according to the present invention.

2, the vehicle anti-lock brake system according to the invention a plurality of solenoids for controlling the braking hydraulic pressure transmission to the hydraulic brake 23 side installed on the front wheel (FR) (FL) and the rear wheel (RR) (RL). Pumping oil stored in the valves 33A and 33B, the low pressure accumulator 34 in which oil escaping from the hydraulic brake 23 side is temporarily stored in the decompression braking operation, and the storage accumulator 34 in the boost / hold braking operation. High pressure accumulator having an orifice 36a at the outlet side to reduce pressure pulsation of oil pressurized and discharged by driving the motor 35, a pair of pumps 40L and 40R, and pumps 40L and 40R. 36, which are compactly installed in the modulator block 31. As shown in FIG.

The plurality of solenoid valves are connected to the upstream side of the hydraulic brake 23 and are normally connected to the NO type solenoid valve 33A and the downstream side of the hydraulic brake 23 and are normally closed. It is distinguished by the NC type solenoid valve 33B which is maintained. The opening and closing operation of the solenoid valves 33A and 33B is respectively performed by the ECU 32 which detects the vehicle speed through the wheel sensors 24 disposed on the front wheel FR and FL. To be controlled. In addition, the NC type solenoid valve 33B is opened according to the depressurizing braking action so that the oil exiting from the hydraulic brake 23 side is temporarily stored in the low pressure accumulator 34.

In addition, the pair of pumps 40L and 40R are simultaneously driven by the motor 35 with a constant phase difference, whereby the oil stored in the low pressure accumulator 34 is pressurized and supplied to the high pressure accumulator 36 side. As the pressure pulsation is reduced in the high pressure accumulator 36, the pressure pulsation 36 is returned to the hydraulic brake 23 or the master cylinder 22 again along the hydraulic line.

On the other hand, the pump 40L (40R) is provided with a bypass means 50 in order to more effectively reduce the pressure pulsation of the oil, the detailed structure thereof will be described with reference to Figs. (A pair of pumps are configured to be symmetrically with respect to the rotation axis of the motor, so that only one of the pair of pumps is enlarged in FIG. 3.)

Referring to FIG. 3, a motor 35 is provided on the side of the modulator block 31 so that the rotation shaft 35a protrudes to drive the pumps 40L and 40R. At this time, the front end of the rotating shaft 35a is composed of an eccentric shaft 35b, which is disposed to be in contact with the pair of pumps 40L and 40R, that is, the piston 41 to be described later, thereby providing a pair of pumps 40L. (40R) is driven simultaneously with a 180 degree phase difference.

Further, in order to install the pumps 40L and 40R in the modulator block 31, the bores 31a, which are open at both ends in the transverse direction, on the center of the bore 31a and the low-pressure accumulator 34 The suction port 31b for communicating the side, the discharge port 31c for communicating the open end side of the bore 31a, and the high pressure accumulator 36 side, etc. are processed.

In addition, the pumps 40L and 40R are slidably installed in the bore 31a and slidably from side to side. The pump 41L has a suction passage 41a formed therein in the axial direction, and the suction passage is installed at the tip of the piston 41. The inlet valve 42 for opening and closing 41a and the open end of the bore 31a are combined to form a pressurizing chamber 43 between the piston 41 and the outlet valve to prevent backflow of oil. The plug 44 in which 45 is arrange | positioned, and the bypass means 50 for reducing the pressure pulsation in the pressurizing chamber 43 are provided.

At this time, the suction passage 41a of the piston 41 is connected to the low pressure accumulator 34 through the suction port 31b, and the discharge side of the pressurizing chamber 43 has a discharge passage 44a formed in the plug 44. It is connected with the hydraulic line by the side of the master cylinder 22 and the hydraulic brake 23 via the discharge port 31c. Reference numeral "41b" is an O-ring provided on the outer periphery of the piston 41 to prevent leakage of oil.

The inlet valve 42 is provided with a sphere 42a disposed on the outlet side of the suction passage 41a of the piston 41, an elastic member 42c and a retainer 42b for elastically supporting the sphere 42a. . In addition, the outlet valve 45 operates opposite to the inlet valve 42 according to the position of the piston 41 to open and close the discharge passage 44a, and the sphere 45a, the elastic member 45c, and the center are opened. It consists of a valve seat 45b and is installed in the plug 44. Reference numeral 46 denotes a return spring provided between the tip of the piston 41 and the plug 44, that is, in the pressure chamber 43 to support the piston 41 in the bottom dead center direction (arrow B direction).

On the other hand, the bypass means 50 is to primarily reduce the pressure pulsation of the oil in the pressure chamber 43, the predetermined depth to the bore (31a) of the modulator block 31 to communicate with the pressure chamber 43. The mounting bore 51, the check valve 52 installed in the mounting bore 51 to control the hydraulic pressure transmission, one end is in communication with the bottom of the mounting bore 51, the other end of the hydraulic line on the low pressure accumulator 34 side (34a, see FIG. 2), i.e., a bypass hydraulic line 53 is connected to the downstream side of the pumps 40L and 40R to bypass a part of the hydraulic pressure when the check valve 52 is opened.

In addition, the check valve 52 is press-fitted into the mounting bore 51 and the valve housing 52a in which the orifice 52b is formed in the axial direction, and the orifice 52b are disposed in the valve housing 52a so as to move forward and backward. The spherical body 52c for opening and closing, the elastic member 52d for elastically supporting the spherical body 52c in the direction of closing the orifice 52b, and the rear end of the valve housing 51a are pushed out of the elastic member 52d. To prevent and consists of a stopper (52e) is formed with an oil passage (52f) on the center. At this time, the elastic support force (52d) of the elastic member of the check valve 52 is preferably configured to be slightly smaller than the elastic support force of the elastic member 45c of the outlet valve (45), the pressure chamber 43 is a predetermined pressure or more In the case of going up, the check valve 52 of the bypass means 50 is opened before the outlet valve 45 to bypass a part of the hydraulic pressure.

Next, the operation and effect of the anti-lock brake system according to the present invention configured as described above will be described.

When a vehicle slip occurs, the anti-lock brake system receives three types of pressure reduction, boost, and maintenance based on signals input from each wheel sensor 24 on the front wheel FR and FL rear wheels. Mode is controlled. At this time, each control state is not controlled to the same state in both front wheel (FR) (FL) and rear wheel (RR) (RL), but is controlled separately according to the friction conditions, that is, three modes are mixed. Explain the braking force decompression operation.

First, if the braking pressure in the hydraulic brake 23 is greater than the road surface condition while the braking force is being exerted by the braking hydraulic pressure formed through the booster 21 and the master cylinder 22 by stepping on the brake pedal 20, the appropriate pressure is achieved. Should be lowered. Therefore, the ECU 32 opens and operates the NC type solenoid valve 33B, which causes some of the oil to escape from the hydraulic brake 23, which is temporarily stored in the low pressure accumulator 34. Through this process, the braking pressure in the hydraulic brake 23 mounted on the front wheel FR and the rear wheel RR RL side is lowered, thereby preventing the phenomenon of sliding on the road surface.

The following describes the braking force boosting operation of the antilock brake system. If the decompression state lasts for a long time during the control of the anti-lock brake system, the vehicle braking efficiency is reduced. Activate 40L) (40R).

Therefore, the oil stored in the low pressure accumulator 34 is pressurized through the pumps 40L and 40R and transferred to the high pressure accumulator 36 side. That is, when the piston 41 moves to the bottom dead center (arrow B direction), oil flows into the pressure chamber 43 through the suction flow path 41a and the inlet valve 42, and the piston 41 moves to the top dead center. The lower surface (arrow C direction) oil is pressurized in the pressurizing chamber 43 to open the outlet valve 45, and is then transferred to the high pressure accumulator 36 through the discharge passage 44a and the discharge port 31c, and the high pressure accumulator At (36) the oil pressure pulsation is reduced.

The pressurized oil which is continuously reduced in pressure pulsation is delivered to the hydraulic brake 23 side through the open-type NO solenoid valve 33A, whereby the braking hydraulic pressure is increased. At this time, since the pressurized oil discharged to the hydraulic line passes through the orifice 36a of the high pressure accumulator 36, the pressure pulsation of the oil is reduced again.

In addition, in the antilock brake system control, in order to reach the state where the braking pressure generates the optimum braking force or to prevent the resonance of the vehicle, a pressure holding operation for maintaining the braking pressure in a constant state is required. That is, the pressure holding operation prevents the pressure change in the hydraulic brake 23, and closes the NO type solenoid valve 33A on the hydraulic brake 23 side to maintain the braking pressure, thereby preventing the hydraulic pressure from being transmitted. . Accordingly, the pressurized oil discharged from the high pressure accumulator 36 is transferred to the master cylinder 22 side, whereby the pressure holding operation is performed.

The oil stored in the low pressure accumulator 34 is pressurized by the operation of the pumps 40L and 40R during the pressure increasing operation and the pressure holding operation, and passes through the high pressure accumulator 36 and the orifice 36a to the NO solenoid valve 33A or It is supplied to the master cylinder 22 side.

At this time, since the piston 41 of the pumps 40L and 40R is driven with a constant phase difference, a pressure peak of a constant peak is periodically generated in the pressure chamber 43 of the pumps 40L and 40R. This is significantly reduced through the bypass means 50 before exiting the outlet valve 45.

That is, when the oil pressure in the pressure chamber 43 rises above a predetermined pressure, as shown in FIG. 5, a part of the oil in the pressure chamber 43 opens the check valve 52 of the bypass means 50 while opening the valve. Orifice 52b of housing 52a Bypass hydraulic line 53 By escaping to the low pressure accumulator 34 side hydraulic line 34a, the pressure pulsation in the pressurizing chamber 43 is primarily reduced. When the pressure in the pressure chamber 43 drops to some extent, the check valve 52 is immediately closed, and most of the oil pressure passes through the outlet valve 45 toward the high pressure accumulator 36 to perform a braking action.

As a result, the oil flowing out through the outlet valve 45 is in a state where the pressure pulsation is primarily reduced through the bypass means 50, and the pressure pulsation continues through the high pressure accumulator 36 and the orifice 36a. It is completely reduced in 2nd and 3rd order.

As described in detail above, according to the anti-lock brake system according to the present invention, when the pressure pulsation of the periodic oil generated in the pressure chamber by the reciprocating motion of the pump piston rises above a predetermined pressure, a part of the hydraulic pressure before exiting the outlet valve Bypass means are bypassed to the pump downstream side and reduced. Therefore, the pressure pulsation of the oil is more efficiently and completely reduced through the bypass means and the high pressure accumulator, which reduces the operating noise of the anti-lock brake system, and also improves the reliability of the product because the vibration of the brake pedal does not occur. There is.

Claims (2)

It is provided in the bore formed in the modulator block and provided with a pump for suctioning the oil in the low pressure accumulator and forcibly pumped to the high pressure accumulator side when the pressure boosting or pressure holding braking action, The pump is installed in the bore to reciprocate and has a suction flow path formed therein, an inlet valve provided at the front end of the piston to open and close the suction flow path, and installed at the open end of the bore and the piston tip In the anti-lock brake system having a valve housing with a pressurized chamber formed between the pressure chamber, When the mounting bore 51 provided in communication with the pressure chamber 43 in the bore 31a of the modulator block 31 and the mounting bore 51 and the pressure chamber 43 rises above a predetermined pressure The check valve 52 is opened and one end is in communication with the bottom of the mounting bore 51, and the other end is connected to the hydraulic line 34a on the low pressure accumulator 34 side so that the hydraulic pressure when the check valve 52 is opened. And bypass means (50) including a bypass hydraulic line (60) for guiding a portion of said pump (40L) (40R) downstream. The method of claim 1, The check valve 52, A valve housing 52a press-fitted to the mounting bore 51 and having an orifice 52b therein; a sphere 52c embedded in the valve housing 52a to open and close the orifice 52b; and the sphere An elastic member 52d for elastically supporting the 52c, and a stopper 52e provided at the rear end of the valve housing 52a to prevent the elastic member 52d from being separated, and having an oil passage 52f formed therein. Featuring anti-lock brake system.