KR100402278B1 - Solenoid Valve of Anti-Lock Brake system - Google Patents

Abstract

The present invention provides a solenoid valve of an anti-lock brake system capable of exhibiting stable braking performance by preventing the piston from rising even when a sudden pressure difference occurs in the upstream and downstream sides of the fixed orifice during general braking. This solenoid valve is installed in the magnetic core, valve housing, magnetic core and plunger which is arranged to be movable by electromagnetic force and elastic force, and is inserted in the lower part of the magnetic core and has a fixed orifice for communicating the oil inlet and oil outlet. The lower end is placed on the valve housing so that the valve seat and the fixed orifice of the valve seat can move upward, and the upper part is disposed inside the valve seat. A hydraulic guide member fixed to the valve housing and having an upper portion thereof has an oil channel formed by forming a fine gap in the axial direction between the outer circumference of the hydraulic guide member and the inner circumference of the piston.

Description

Solenoid valve of anti-lock brake system {Solenoid Valve of Anti-Lock Brake system}

The present invention relates to an antilock brake system, and more particularly, to a solenoid valve of an antilock brake system capable of exhibiting more efficient braking performance by varying the amount of braking oil supplied during slip control.

In general, the anti-lock brake system is composed of a wheel cylinder installed on a wheel of a vehicle to apply a braking force through hydraulic pressure, a master cylinder and a power booster to transfer the braking oil to the wheel cylinder, a modulator block and an ECU to control the braking hydraulic pressure. To control the braking force. The modulator block is provided with a normal open solenoid valve and a normal closed solenoid valve for controlling the supply of braking oil.

1 is a cross-sectional view showing the internal structure of a conventional general open solenoid valve used in an anti-lock brake system. The solenoid valve 10 includes a magnetic core 2 mounted on the modulator block 1, a plunger 3 and a valve seat 4 provided inside the magnetic core 2. The plunger 3 is disposed on the upper portion of the valve seat 4 so that the plunger can move up and down by the electromagnetic force by the spring 5 and an external power source. An inlet portion 6 connected to a master cylinder (not shown) and a pump (not shown) is formed at a lower portion of the solenoid valve 10, and an outlet portion 7 connected to a wheel cylinder (not shown) is formed at a side thereof. Is formed. The flow of oil for braking is controlled by opening and closing the orifice flow path 8 formed in the valve seat 4 while the plunger 3 moves up and down between the inlet 6 and the outlet 7.

However, in the conventional solenoid valve as described above, the oil flowing by the master cylinder or the pump is transferred or blocked through the orifice flow path to the shock cylinder by a simple opening and closing operation of the plunger, and thus the valve passes through the valve during slip control. The amount of oil will be the same as the flow rate of the oil during normal braking. Therefore, in addition to the noise generated by the pulsation of the oil due to the intermittent opening and closing operation of the plunger during the slip control, the durability of the parts is reduced by repeated vibration. In addition, the pulsation pressure is transmitted to the driver through the pedal to interfere with the driver's comfortable driving.

In order to solve this drawback, a normal open solenoid valve was developed to reduce the pulsation of oil while reducing the amount of oil supplied to the wheel cylinder according to the slip ratio. have. As an example, US Pat. No. 5,647,644 discloses a normally open solenoid valve to achieve the same effect as shown in FIG.

The solenoid valve 20 according to the prior art has a valve housing 22 installed in the modulator block 21, a valve seat 23 installed in the valve housing 22, a magnetic core 24, and a plunger ( 25, and a piston 26. The valve seat 23 has a through hole formed therein and is press-fitted to the lower portion of the valve housing 22, and the magnetic core 24 is installed at the upper portion of the valve housing 22. The plunger 25 is installed through the magnetic core 24, and the lower end thereof is disposed adjacent to the upper end of the valve seat 23. And the piston 26 is arrange | positioned in the outer periphery of the valve seat 23 in the state pushed downward by the spring 27. As shown in FIG. The normally open solenoid valve 20 is configured to form two orifices, one of which is a fixed orifice 30 provided at the upper end of the valve seat 23 formed in a hollow, and the other is the piston 26 in slip control. It is the moving orifice 40 formed by the slot 41 formed in the upper end part of the piston 26 when it contacts this magnetic core 24. As shown in FIG.

On one side of the lower end of the valve seat 23, an auxiliary flow path 31 is formed to allow oil to flow between the valve seat 23 and the valve housing 21, and through the inlet part 28 during slip control. The introduced oil flows through the auxiliary flow passage 31 to move the piston 26 upward.

In the conventional solenoid valve configured as described above, during normal braking, the plunger 25 is held upward by the electromagnetic force, and the piston 26 is held downward by the spring 27, so that the oil is inlet of the valve. After entering 28, it is discharged to the outlet 29 of the valve through the open orifice 30.

On the other hand, during slip control, the plunger 25 moves downward to close the fixed orifice 30, and the oil introduced through the inlet portion 28 flows through the auxiliary flow path 31 to raise the piston 26. To be in contact with the magnetic core 24. Accordingly, when the plunger 25 moves upward, the braking oil generated in the master cylinder passes through the moving orifice 40 formed by the slot 41 of the piston 26 in contact with the magnetic core 24 and the wheel. Delivered to the cylinder.

When the braking force is released in this state, the oil of the wheel cylinder is first returned to the master cylinder through the return passage 32 formed in the valve housing 21 so as to connect the inlet portion 28 and the outlet portion 29 of the oil. The plunger 25 is then moved upwards to return the valve to its original open state.

However, in the conventional normal-open solenoid valve as described above, the pulsation phenomenon of the oil raised in the conventional solenoid valve shown in FIG. 1 because the pressure change due to the intermittent operation of the plunger during slip control is reduced and flows through the moving orifice. However, when the brake pedal is pressed during normal braking, a large amount of braking oil from the master cylinder flows into the inlet of the valve at once, and a rapid pressure difference is formed between the upstream and downstream sides of the fixed orifice. . As a result, a part of the braking oil flowing into the inlet of the valve flows into the auxiliary flow passage in an instant, causing the piston to rise, preventing the braking oil from escaping to the outlet, thus preventing the rapid increase in pressure, thereby increasing the braking distance of the vehicle. There is a problem with losing.

On the other hand, if the size of the fixed orifice is made large, the above problems can be solved. However, when the size of the fixed orifice is increased, a large force braking pressure is applied to the cross section of the plunger. Therefore, in order to close the fixed orifice during slip control, a large force of electromagnetic force is required for the plunger, thereby increasing the size of the magnetic coil installed on the outer circumference of the magnetic core.

The present invention is to solve the problems of the prior art, the object of the present invention is to ensure a stable braking performance by preventing the piston does not rise even if a sudden pressure difference occurs upstream and downstream of the fixed orifice during general braking It is to provide a solenoid valve of an anti-lock brake system.

1 is a cross-sectional view showing the internal structure of a solenoid valve of a conventional anti-lock brake system.

2 is a cross-sectional view showing the internal structure of a solenoid valve of another conventional anti-lock brake system.

Figure 3 is a cross-sectional view of the solenoid valve of the anti-lock brake system according to the present invention, showing a state in which the fixed orifice is fully open during normal braking.

4 illustrates a state in which the fixed orifice of the solenoid valve of FIG. 3 is completely closed by the plunger during slip control.

FIG. 5 illustrates a state in which the piston of the solenoid valve of FIG. 3 contacts the fixed orifice during slip control.

6 illustrates a state in which the fixed orifice of the solenoid valve of FIG. 3 is fully opened during slip control.

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

100. Solenoid valve 103. Plunger

110. Valve seat 111. Fixed orifice

120 Piston 121 Mobile Orifice

130. Valve housing 140. Hydraulic guide member

141. Euros 170. Oil channel

The present invention for achieving this object,

A modulator block having a wheel cylinder, a master cylinder for transferring braking oil to the wheel cylinder, an oil inflow passage communicating with the master cylinder and an oil outflow passage communicating with the wheel cylinder, and inserted into the modulator block In the anti-lock brake system having a solenoid valve for controlling the braking oil flowing from the master cylinder to the wheel cylinder,

The solenoid valve is a magnetic core coupled to the upper portion of the bore formed in the modulator block,

A valve housing installed inside the bore and having a through hole communicating with an oil outflow path at a side thereof;

A plunger disposed in the magnetic core so as to be movable by an electromagnetic force and an elastic force,

A valve seat inserted into a lower portion of the magnetic core in the modulator block, the valve seat having a fixed orifice communicating the oil inlet and the oil outlet;

A piston having a lower end mounted on the valve housing and an upper part disposed inside the valve seat so as to be movable toward the fixed orifice of the valve seat, and having a moving orifice and an oil passage formed on the upper and side surfaces thereof,

A hydraulic pressure guide member having a lower end fixed to the valve housing and an upper end thereof disposed in the piston;

An oil channel formed by forming a fine gap in the axial direction between the outer circumference of the hydraulic guide member and the inner circumference of the piston,

In general braking, the oil introduced through the oil inlet flows quickly through the fixed orifice open to the oil outlet, and when slip control of the fixed orifice is closed, oil introduced through the oil channel. It is characterized in that to move the piston quickly upward by the pressure of.

Preferably, the length of the oil channel is approximately twice the size of the outer diameter of the hydraulic guide member.

Hereinafter, with reference to the accompanying drawings, preferred embodiments according to the present invention will be described in detail.

3 to 6 show a normally open solenoid valve of an anti-lock brake system according to the invention.

As shown in FIG. 3, the normally-open solenoid valve 100 of the present invention is provided with a yoke (not shown) in which a coil is built in an outer circumferential surface thereof, and has a cylindrical sleeve 101 with one surface open, and a sleeve 101. The magnetic core is installed in the interior and coupled to the armature 102 and the plunger 103 coupled thereto by the electromagnetic force generated by the coil, and the end of the magnetic core (bore 105 formed in the modulator block 104) 106).

The valve seat 110 having the fixed orifice 111 having a predetermined diameter is press-fitted into the magnetic core 106. The valve seat 110 includes a piston 120 having a variable orifice 121 to be described later. The fixed orifice 111 is installed so as to be able to contact or spaced apart.

The plunger 103 penetrates the inside of the magnetic core 106 and is positioned adjacent to the fixed orifice 111 of the valve seat 110. The lower end of the plunger 103 is fixed orifice 111 when the plunger 103 moves downward. The ball 103a which closes the upper part of () is attached.

First and second seat surfaces 111a for seating the ball 103a of the plunger 103 and second seat surfaces 111b for seating the upper end of the piston 120 are respectively formed on the upper and lower portions of the fixed orifice 111. It is.

A first spring 107 is provided between the valve seat 110 and the plunger 103 to elastically support the plunger 103 in an upward direction so as to maintain the fixed orifice 111 in a normal state. Between the 120 and the magnetic core 106, a second spring 108 is provided to elastically support the piston 120 in a downward direction so that the piston 120 is spaced apart from the fixed orifice 111 during general braking. .

The modulator block 104 is formed with an oil inlet 151 connected to the master cylinder and the hydraulic pump (not shown), and an oil outlet 152 connected to the wheel cylinder (not shown), so that the master cylinder or the hydraulic pump The discharged oil is delivered to the wheel cylinder through the oil inlet 151, the fixed orifice 111, and the oil outlet 152 to perform braking.

One side of the valve seat 110 press-fitted to the magnetic core 106 is provided with an oil passage 153 formed to be spaced apart from the inner circumferential surface of the magnetic core 106 to communicate with the oil outflow passage 152. A hydraulic chamber 112 is formed inside the valve seat 110, and an upper portion of the piston 120 is slidably disposed along the inner wall of the hydraulic chamber 112. The outer circumferential surface of the upper portion of the piston 120 is provided with a sealing 160 for preventing oil from leaking between the piston 120 and the valve seat 110.

In the bore 105 of the modulator block 104, a valve housing 130 is formed to form a space for the vertical movement of the piston 120 and to restrict the downward movement of the piston 120. The lower portion of the valve housing 130 is installed with a hydraulic guide member 140, the upper portion of which is inserted into the piston 120, the upper end of the hydraulic guide member 140 is in communication with the oil inlet passage 151 The guide passage 141 is formed.

That is, the valve housing 130 and the magnetic core 106 are disposed inside the bore 105 of the modulator block 104 in a state in which the magnetic core 106 is inserted into and coupled to the upper end of the valve housing 130, The valve seat 110 is press-fitted into the magnetic core 106, the piston 120 has an upper end thereof received inside the valve seat 110, and a lower end thereof is restricted in downward movement inside the valve housing 130. It is placed in a state.

As described above, the hydraulic guide member 140 is accommodated in the lower portion of the piston 120, the piston flow passage 123 for communicating the oil inlet passage 151 and the fixed orifice 111 in the upper portion of the piston 120. And a plurality of branch passages 122 formed vertically branched from the piston passage 123 and penetrating the side surfaces of the piston 120, and extending from the piston passage 123 to penetrate the upper end of the piston 120. A moving orifice 121 is provided. The moving orifice 121 has a diameter smaller than that of the fixed orifice 111.

The lower end of the valve housing 130 is provided with a filter 131 for filtering foreign matter contained in the oil flowing through the oil inlet 151.

The lower end of the hydraulic guide member 140 is disposed in close contact with the inner peripheral surface of the valve housing 130, the upper end is disposed on the inner circumference of the lower end of the piston 120, the hydraulic guide member 140 and the piston 120 The oil channel 170 formed with a fine gap therebetween is provided. The front end of the oil channel 170 is connected to the piston flow path 123, and the lower end thereof is connected to the lower end 132 of the piston 120 placed on the valve housing 130. Therefore, the pressure of the oil in the piston passage 123 may be transmitted to the lower end of the piston 120 through the oil channel 170, and the gap of the oil channel 170 may be the branch passage 122 of the piston 120. 2) and the fixed orifice flow path 111 is considerably finer than the cross-sectional area, the oil flowing into the oil inlet 151 at the normal braking is not flowed into the oil channel 170, and falls into the oil outlet 152 Will go out.

Here, the length of the oil channel 170 is preferably to be approximately twice the size of the outer diameter of the hydraulic guide member 140, and the size of the fixed orifice 111 is larger than the size of the moving orifice 121. It is preferable to form smaller than the guide flow path 141 formed in the hydraulic guide member 140.

A sealing 161 is provided between the lower end of the outer surface of the piston 120 and the inner circumferential surface of the valve housing 130 to prevent oil from flowing between the oil channel 170 and the oil outlet passage 152, and the valve housing 130. An oil return path 171 is formed at the lower end of the outer surface of the wheel) in which a check valve 172 is disposed to flow oil back from the wheel cylinder to the master cylinder or the hydraulic pump.

Hereinafter will be described the operation of the solenoid valve according to the present invention configured as described above.

Since the solenoid valve 100 of the present invention is maintained in an open state as shown in FIG. 3 during general braking, the braking hydraulic pressure formed in the master cylinder is guided to the oil inlet 151 and the hydraulic guide member 140. ), The branch passage 122 and the moving orifice 121 of the piston 120, the fixed orifice 111 of the valve seat 110 and the oil passage 153, and the oil outflow passage 152 in order to pass through the wheel The brake is delivered to the cylinder. At this time, the oil introduced into the piston passage 123 may flow into the oil channel 170 formed between the piston 120 and the hydraulic guide member 140, but the gap of the oil channel 170 is fixed orifice ( Since it is relatively fine compared to the size of 111, the oil channel 170 passes through the oil outflow path 152 without hydraulic pressure being applied. That is, during normal braking, upward movement of the piston 120 does not occur due to oil inflow into the oil channel 170.

When the driver releases the brake pedal in the above state, the braking oil in the wheel cylinder is returned to the master cylinder through the open solenoid valve 100 to release the braking.

Meanwhile, when the vehicle slips during braking, the slip is controlled by depressurizing, maintaining and increasing the braking hydraulic pressure, which will be described with reference to FIGS. 4 to 6.

First, when a current is supplied to the solenoid valve 100 to lower or maintain the braking hydraulic pressure in the wheel cylinder to an appropriate pressure in the decompression and holding mode of the braking hydraulic pressure, as shown in FIG. 1 While the spring 107 is compressed and lowered, the ball 103a is seated on the first seat surface 111a so that the fixed orifice 111 is completely closed, so that the braking hydraulic pressure is no longer transmitted to the wheel cylinder.

On the other hand, since the braking hydraulic pressure is continuously transmitted through the oil inflow path 151, the pressure in the solenoid valve 100 is rapidly increased. The increased braking hydraulic pressure acts on the oil channel 170 between the piston 120 and the hydraulic guide member 140. When the braking hydraulic pressure is greater than a predetermined pressure difference between the two sides of the fixed orifice 111, it is shown in FIG. As shown, the braking hydraulic pressure transmitted to the lower end 132 of the piston 120 through the oil channel 170 ascends the piston 120 while compressing the second spring 108 so that the upper end of the piston 120 is valved. It is to be seated on the second sheet surface 111b of the sheet 110. As a result, in the state where the upper part of the fixed orifice 111 is completely closed by the ball 103a of the plunger 103, the lower part of the fixed orifice 111 is maintained in communication with the moving orifice 121 of the piston 120. Done.

When the braking hydraulic pressure is increased in the above state, current supply to the solenoid valve 100 is stopped and as shown in FIG. 6, the plunger 103 moves upward by the elastic restoring force of the first spring 107. The fixed orifice 111 is opened. Accordingly, the oil in the moving orifice 120 is transferred to the wheel cylinder through the fixed orifice 111 and the oil passage 153 to increase the braking hydraulic pressure. At this time, a significant pressure difference is formed on both sides of the fixed orifice 111, but the hydraulic pressure is stably transmitted through the moving orifice 121 having a smaller diameter than the fixed orifice 111.

When the pressure difference between both sides of the fixed orifice 111 is resolved due to the continuous hydraulic transmission, the piston 120 moves downward by the elastic restoring force of the second spring 108 so that the second seat surface of the valve seat 110 ( It is spaced apart from the 111b), whereby the braking hydraulic pressure is smoothly transmitted to the fixed orifice 111 not only through the moving orifice 121, but also through the branch flow passage 122.

In conclusion, in the case of performing the boosting mode after the maintenance mode of the braking hydraulic pressure during slip control, first, the braking hydraulic pressure is stably transmitted through the moving orifice 121 and the fixed orifice 111 so that both sides of the fixed orifice 111 can be transferred. The hydraulic shock and noise at the boundary are considerably reduced and the braking action is also stable.

As described in detail above, the solenoid valve of the anti-lock brake system according to the present invention has an oil channel formed by forming a minute gap in the axial direction between the piston and the hydraulic guide member, so that both sides of the fixed orifice according to rapid braking during normal braking are provided. Even if there is a sudden pressure difference in the oil channel, the pressure transfer to the lower end of the piston through this oil channel is delayed so that the flow path of the fixed orifice due to the upward movement of the piston is not obstructed. This oil channel allows the piston to be quickly transferred to the lower end of the piston so that a smooth upward movement of the piston can be achieved. Therefore, the anti-lock brake system equipped with the solenoid valve of the present invention has the advantage of always exhibiting stable braking performance.

Claims (4)

A modulator block having a wheel cylinder, a master cylinder for transferring braking oil to the wheel cylinder, an oil inflow passage communicating with the master cylinder and an oil outflow passage communicating with the wheel cylinder, and inserted into the modulator block In the anti-lock brake system having a solenoid valve for controlling the braking oil flowing from the master cylinder to the wheel cylinder, The solenoid valve is a magnetic core coupled to the upper portion of the bore formed in the modulator block, A valve housing installed inside the bore and having a through hole communicating with an oil outflow path at a side thereof; A plunger disposed in the magnetic core so as to be movable by an electromagnetic force and an elastic force, A valve seat inserted into a lower portion of the magnetic core in the modulator block, the valve seat having a fixed orifice communicating the oil inlet and the oil outlet; A piston having a lower end mounted on the valve housing and an upper part disposed inside the valve seat so as to be movable toward the fixed orifice of the valve seat, and having a moving orifice and an oil passage formed on the upper and side surfaces thereof, A hydraulic pressure guide member having a lower end fixed to the valve housing and an upper end thereof disposed in the piston; An oil channel formed by forming a fine gap in the axial direction between the outer circumference of the hydraulic guide member and the inner circumference of the piston, In general braking, the oil introduced through the oil inlet flows quickly through the fixed orifice open to the oil outlet, and when slip control of the fixed orifice is closed, oil introduced through the oil channel. Solenoid valve of the anti-lock brake system, characterized in that to quickly move the piston upward by the pressure of. The method of claim 1, The length of the oil channel is a solenoid valve of the anti-lock brake system, characterized in that approximately twice the size of the outer diameter of the hydraulic guide member. The method of claim 1, The solenoid valve of the anti-lock brake system, characterized in that the guide passage for guiding the oil introduced through the oil inlet passage to the fixed orifice is formed on the upper end of the hydraulic guide member. The method of claim 3, wherein The solenoid valve of the anti-lock brake system, characterized in that the size of the fixed orifice is larger than the size of the movable orifice and smaller than the guide passage.