JP2003343754A - Normally closed solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a normally closed solenoid valve, capable of reducing noise such as hitting sound in the valve opening motion and reducing the energy consumption. <P>SOLUTION: As a current is carried to a coil unit 13, a movable core 28 is attracted toward a fixed core 25. Then, a buffer member 29 abuts to the fixed core 25 against the spring load of a first return spring 30, and then, the movable core 28 abuts to the fixed core 25 against the spring load of a second return spring 32 which is larger than the spring load of the first return spring 30 while the buffer member 29 abuts to the fixed core 25 to open a valve. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a normally closed solenoid valve provided in, for example, a hydraulic circuit of an antilock brake device for a vehicle. 2. Description of the Related Art In an anti-lock brake device for a vehicle, a normally open solenoid valve and a normally closed solenoid valve are provided for each wheel brake in a hydraulic circuit that connects a brake master cylinder and a wheel brake. Have been. [0003] The structure of a general normally closed solenoid valve will be described. The normally closed solenoid valve includes a valve operating unit that opens and closes the valve, and a coil unit that operates the valve operating unit by controlling energization of a coil winding wound around a bobbin. The energization of the coil unit is controlled by an electronic control unit (ECU). In the valve operating unit, one end of a pipe body is fitted into a metal base (modulator body) in which a brake fluid flow path is formed. The other end of the pipe body is fitted with a bobbin and has a coil unit mounted thereon. A fixed core is fitted into the other end of the pipe body, and the pipe body is welded. A valve seat member having a liquid chamber formed at the center in the axial direction is fitted into one end of the pipe body. A movable core is provided movably between the fixed core and the valve seat member. The movable core is urged by a return spring elastically mounted between the movable core and the fixed core, so that a valve element provided at the tip sits on a valve seat member to shut off the liquid chamber. The pipe body is provided with a communication hole communicating with a first base liquid passage formed on the base and communicating with the wheel cylinder. The liquid chamber formed inside the valve seat member communicates with the second base liquid passage communicating with the reservoir through a communication hole provided at one end of the pipe body. In the normally-closed solenoid valve, in the pressure increasing mode and the holding pressure mode, a valve body provided at a distal end portion of the movable core biased by a return spring closes a valve seat member. When the mode shifts to the pressure reduction mode, the coil unit is energized, the movable core is attracted to the fixed core side against the urging force of the return spring, and comes into contact with the movable core, whereby the valve element is separated from the valve seat member and opened. At this time, the brake fluid flows into the pipe body from the first fluid passage on the wheel cylinder side through the communication hole. Then, the brake fluid is discharged to the second fluid passage on the reservoir side through the fluid chamber in the valve seat member. As a normally closed solenoid valve, for example, a solenoid valve disclosed in Japanese Utility Model Registration No. 2569208 has been proposed. In the normally closed type solenoid valve, the valve body of the movable core is seated on the valve seat member and closed by only the urging force of the return spring except in the pressure reduction mode. The return spring has a relatively large spring load. For this reason, when the coil unit is energized when shifting from the pressure increasing mode or the holding pressure mode to the pressure reducing mode, the movable core is attracted to the fixed core side by a large electromagnetic force against a high spring load of the return spring and abuts thereon. For this reason, there is a problem that the operating noise when contacting the fixed core is increased. In addition, there is a problem that energy consumption increases because a large electromagnetic force is generated in the coil unit when sucking the movable core. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a normally-closed solenoid valve capable of reducing noise such as a tapping sound during a valve opening operation and reducing energy consumption. [0008] In order to solve the above problems, the present invention has the following arrangement. That is, in a normally closed solenoid valve including a coil unit in which a coil winding is wound around a bobbin, and a valve operating unit that opens by energizing the coil unit, the valve operating unit includes a fixed core, A first return spring and a second return spring having a higher spring load are inserted in series between the fixed core and the fixed return core in this order via a cushioning member. A valve seat provided at the tip of the movable core and having a valve hole in which a valve body is seated. The movable core is attracted to the fixed core by energizing the coil unit, and the buffer member is Is the first
The movable core contacts the fixed core against the spring load of the second return spring while the cushioning member contacts the fixed core against the spring load of the return spring. It is characterized in that it opens in contact with the valve. Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 is a cross-sectional view of a normally closed solenoid valve, FIG. 2 is a partially cutaway view of a base body (modulator body) in which the solenoid valve is incorporated, and FIG. 3 is a schematic diagram of a hydraulic circuit of an antilock brake device for a vehicle. FIG. First, a schematic configuration of an antilock brake device for a vehicle will be described with reference to FIGS. In FIG. 3, reference numeral 1 denotes an electronic control unit (ECU),
The operation of the hydraulic circuit constituting the actuator 2 is controlled. M / C is a brake master cylinder which is connected to the hydraulic circuit of the actuator 2 and outputs a brake hydraulic pressure from each cylinder chamber according to the amount of depression of the brake pedal P. F
1, Rr, Rl, Fr are front left wheels, rear right wheels, rear left wheels, front right wheels, and wheel brakes B (Fl), B (Rr), B (Rl), B ( Fr) are provided. A wheel cylinder (not shown) for operating each wheel brake is connected to a hydraulic circuit of the actuator 2. The structure of the actuator 2 will be described.
(Fl), B (Rr), B (Rl), B (Fr) normally open solenoid valves IV (Fl),
IV (Rr), IV (Rl) and IV (Fr). For each of these four normally-open solenoid valves, the normally-closed solenoid valves OV (Fl), OV (Rr), OV (Rl), OV (F
r) are connected in parallel. Normally closed solenoid valve OV
(Fl) and OV (Rr) are stored in the reservoir 3 for temporarily storing the brake fluid, and the normally-closed solenoid valves OV (Rl) and OV (Fr)
r) are each connected to a reservoir 4 for temporarily storing brake fluid. The reservoirs 3, 4 are connected to suction ports of plunger pumps 5, 6, and the plunger pumps 5, 6 circulate the brake fluid from the reservoirs 3, 4 so as to return to the brake master cylinder M / C. Let it. Reference numeral 7 denotes a pump operating motor. When the motor is driven to rotate, the piston reciprocates to operate the plunger pumps 5, 6. A damper D is provided in the fluid passage between the plunger pumps 5, 6 and the brake master cylinder M / C to absorb the pulsation of the fluid pressure. Each normally open solenoid valve IV and each normally closed solenoid valve OV
Is controlled by the electronic control unit 1. Also, normally open solenoid valves IV (Fl), IV (Rr), IV
(Rl), IV (Fr) have check valves 8 (Fl),
8 (Rr), 8 (Rl) and 8 (Fr) are connected in parallel, and after releasing the input to the brake master cylinder M / C, the corresponding wheel brakes B (Fl) and B (Fl)
The valve is opened to directly return the brake fluid from (Rr), B (Rl), and B (Fr) to the brake master cylinder M / C. The electronic control unit 1 controls each wheel Fl, R
The running state of the vehicle is input from a wheel speed sensor (not shown) provided at r, Rl, Fr. The electronic control unit 1 controls each wheel brake B (F
1) Open each normally-open solenoid valve IV to the actuator 2 according to the running state of the vehicle for each of B), B (Rr), B (Rl), and B (Fr). A pressure increasing mode in which the OV is closed to increase the braking torque by increasing the hydraulic pressure applied from the brake master cylinder M / C to the wheel cylinder (not shown), each normally open solenoid valve IV and each normally closed solenoid Valve O
V is closed so that the hydraulic pressure is not transmitted from the brake master cylinder M / C to the wheel cylinder (not shown) to maintain the braking torque.
Is closed, and each normally closed solenoid valve OV is opened to temporarily store brake fluid in the reservoirs 3 and 4 from the wheel cylinders, thereby reducing the braking torque so that the wheels are not locked. It is controlled by one of the mode commands. Among these, for example, when shifting to the depressurization mode, the electronic control unit 1 drives the pump operating motor 7 to operate the plunger pumps 5 and 6 to store the brake fluid temporarily stored in the reservoirs 3 and 4 in the brake master. It returns to the cylinder M / C side. In FIG. 2, a normally open solenoid valve IV (F
l), IV (Rr), IV (Rl), IV (Fr) and normally closed solenoid valves OV (Fl), OV (Rr), OV (R
1), OV (Fr) is connected to a hydraulic circuit for brake fluid provided on a metal base (modulator body) 9. Each normally open solenoid valve IV and each normally closed solenoid valve OV are electrically connected to the electronic control unit 1 through terminals 10 and 11. A pump operating motor 7 for operating the plunger pumps 5 and 6 is integrally attached to a metal base (modulator body) 9. Normally closed solenoid valves OV (Fl), OV (R
r), OV (Rl) and OV (Fr) will be described with reference to FIG. Although four normally closed solenoid valves OV are provided, one of them will be described as a representative. The normally closed solenoid valve OV includes a coil unit 13 in which a coil winding 35 is wound around a bobbin 24, and a valve operating unit 12 that is opened by energizing the coil unit 13. The structure of the valve operating unit 12 will be described. The valve actuating unit 12 is a metal base (modulator body) in which the first base liquid passage 14 for the brake fluid from the wheel cylinder side and the second base liquid passage 27 communicating with the reservoirs 3 and 4 are formed. 9 are fitted in the fitting holes 15. Specifically, one end of the pipe body 16 is fitted into the fitting hole 15, and is detached by a retaining ring 18 engaged between the plug 17 fitted on the outer periphery of the pipe body 16 and the concave groove on the inner wall of the fitting hole. Not to be. Further, seal rings 19 and 20 are fitted on the outer periphery of the pipe body 16 in the longitudinal direction. A communication hole 21 communicating with the first base fluid passage 14 on the wheel cylinder side of the base (modulator body) 9 is formed in the pipe body 16 corresponding to an area partitioned in the axial direction by the seal rings 19 and 20. I have. A filter device 22 is fitted so as to cover the communication hole 21, and the filter device 22 filters the brake fluid flowing inside the pipe body 16. A valve hole 26b is formed in a seating portion 26a of a valve seat member 26 provided in the pipe body 16, and the valve hole 26b is formed in the valve seat member 2.
6 communicates with a liquid chamber 23 provided at the axial center. The liquid chamber 23 communicates with a second base liquid passage 27 on the reservoir side of the base (modulator body) 9 through a communication hole 16 a provided on the lower surface of the pipe body 16. The first base liquid passage 14, the liquid chamber 23, and the second base liquid passage 27 mainly serve to return the brake fluid flowing from the wheel cylinder side to the reservoir side with the valve operating unit 12 opened in the decompression mode. Used as a road. As described above, one end of the pipe body 16 is fitted into the fitting hole 15 of the base (modulator body) 9, and the other end is inserted into the bobbin 24 of the coil unit 13. The other end of the pipe body 16 is a fixed core 25.
And welded together. The fixed core 25 is also inserted into the bobbin 24. A valve seat member 2 is provided at one end of the pipe body 16.
6 is press-fitted and fixed. A movable core 28 is inserted into the pipe body 16 between the fixed core 25 and the valve seat member 26 so as to be movable in the axial direction. Further, a first return spring 3 is provided between the movable core 28 and the fixed core 25.
0 and a second return spring 32 having a higher spring load than the first return spring 30
9 in this order in series. The buffer member 29 is provided in the liquid chamber 28 of the movable core 28.
The movable core 28 is inserted so as to be relatively movable in the axial direction along with the movement of the movable core 28. The cushioning member 29 includes a cylindrical portion 29 a formed in a cylindrical shape and a butting portion 29 extended in a rod shape.
b, and is inserted into the liquid chamber 28a with the cylindrical portion 29a facing downward. Further, a cylindrical receiving member 31 is press-fitted and fixed to the opening side of the liquid chamber 28a of the movable core 28, and transmits the spring load of the first return spring 30 to the buffer member 29. . When the cushioning member 29 is not operated, the cylindrical portion 29 a is in contact with the receiving member 31, and the abutting portion 29 b extends through the receiving member 31 toward the fixed core 25. The first return spring 30 is elastically mounted with the upper end abutting on the fixed core 25 and the lower end abutting on the receiving member 31. Also, the second return spring 3
2 has an upper end in contact with the cylindrical portion 29a and a lower end in the movable core 28.
And a liquid chamber wall surface 28b. The movable core 28 is closed by the action of only the spring load of the first return spring 30. Also, the cushioning member 29
The gap A between the butting portion 29b and the fixed core 25 is set smaller than the gap B between the movable core 28 and the fixed core 25. Thereby, the movable core 29 is fixed core 2
5, first, the abutting portion 2 of the buffer member 29
9 b is abutted on the end face of the fixed core 25. A valve body 33 made of, for example, a steel ball is provided at the tip of the movable core 28. The movable core 28 is first,
The second return springs 30 and 32 are constantly urged in the valve closing direction, and the valve body 33 provided at the distal end always contacts the valve seat member 26 to shut off the liquid chamber 23.
A shut plate 25a is provided on the abutting end surface (upper surface) of the fixed core 25. The movable core 28 is attracted to the fixed core 25 by energization of the coil unit 13, and opens when the valve element 33 is separated from the valve seat member 26. The coil unit 13 has a connection terminal portion 34 having conductivity, which is fixed to one side of a bobbin 24 made of an insulating resin material or the like in a direction hanging from the bobbin 24. A coil winding 35 wound around the bobbin 24 is connected to the connection terminal portion 34. A yoke 36 is fitted on the outer peripheral side of the bobbin 24 to form a magnetic path. The other end of the pipe body 16 and the fixed core 25 are fitted into the inner peripheral side of the bobbin 24. The connection terminal 34 is connected to the terminal 10 that is electrically connected to the electronic control unit 1 by welding (see FIG. 2). Next, the opening and closing operation of the normally closed solenoid valve OV will be described with reference to FIG. In the pressure increasing mode in which the brake pressure from the master cylinder M / C is increased by the operation of the brake pedal, and in the holding pressure mode in which the brake pressure is maintained, the coil unit 13 is not energized and the first return is performed. The valve element 33 of the movable core 28 is seated on the valve seat member 26 by the bias of the spring 30 and is closed. When the brake master cylinder M / C is released and the mode shifts to the pressure reducing mode for reducing the brake pressure, the coil unit 13 is energized, the movable core 28 is sucked toward the fixed core 25, and the buffer member 29 is first released. 1 fixed core 2 against the low spring load of return spring 30
5 and then the movable core 28 slides on the outer periphery of the buffer member 29 against the high spring load of the second return spring 32 to contact the fixed core 25 to open the valve. At this time, the brake fluid flows into the pipe body 16 through the communication hole 21 from the first base fluid passage 14 on the wheel cylinder side. The brake fluid that has flowed into the pipe body 16 flows into the fluid chamber 23 provided at the axial center of the valve seat member 26 via the valve hole 26b, and the communication hole 1
The brake fluid is returned to the second base fluid passage 27 on the reservoir 3, 4 side through 6a. When the mode is switched from the pressure reduction mode to the holding pressure or pressure increase mode, the power supply to the coil unit 13 is stopped, and the movable core 28 is moved downward by the urging force of the first and second return springs 30 and 32 in the figure. Move to valve body 3
3 is seated on the valve seat member 26 to close the valve. According to the above configuration, when the normally closed solenoid valve VO shifts from the closed state to the open state, the coil unit 1
When the movable core 28 is attracted to the fixed core 25 side by energization of the movable core 3, the butting portion 29 b of the buffer member 29 abuts against the fixed core 25 against the spring load of the first return spring 30, and the movable core 28 28 and fixed core 25
After the gap between the movable core 28 and the movable core 28 is
Abuts against the fixed core 25, so that the operating noise when contacting the fixed core 25 can be reduced. Further, since the return speed of the movable core 28 can be suppressed, the pulsation of the brake fluid can be reduced, and the occurrence of oil hammering noise can be suppressed. Further, the electromagnetic force generated in the coil unit 13 when attracting the movable core 28 can be reduced, so that energy consumption can be reduced. Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the material of the buffer member 29 may be either a resin material or a metal material. The shape is also arbitrary. Of course, many modifications can be made without departing from the spirit of the law. According to the structure of the normally closed type solenoid valve according to the first aspect, the energization of the coil unit causes the movable core to be attracted to the fixed core side, and the buffer member is first returned to the first return position. The valve is opened by contacting the fixed core against the spring load of the spring, and then the movable core contacts the fixed core against the spring load of the second return spring, so that the gap between the movable core and the fixed core is increased. After is sufficiently reduced, the movable core comes into contact with the fixed core against the spring load of the second return spring, so that the operating noise when contacting the fixed core can be suppressed. In addition, since the return speed of the movable core can be suppressed, the pulsation of the brake fluid can be reduced, and the occurrence of oil hammering noise can be suppressed. Further, the electromagnetic force generated in the coil unit when attracting the movable core can be reduced, so that energy consumption can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory sectional view of a normally closed solenoid valve. FIG. 2 is a partially cutaway explanatory view of a base (modulator body) in which an electromagnetic valve is incorporated. FIG. 3 is an explanatory diagram schematically showing a hydraulic circuit of the antilock brake device for a vehicle. [Description of Signs] 1 Electronic control unit 2 Actuator 3, 4 Reservoir 5, 6 Plunger pump 7 Pump operating motor 8 Check valve 9 Base 10, 11 Terminal 12 Valve operating unit 13 Coil unit 14 First base fluid path 15 fit Mating hole 16 Pipe body 17 Plug 18 Retaining ring 19, 20 Seal ring 21 Communication hole 22 Filter device 23, 28a Liquid chamber 24 Bobbin 25 Fixed core 25a Shut plate 26 Valve seat member 27 Second base liquid path 28 Moving core 28b Liquid Room wall 29 Buffer member 29a Cylindrical portion 29b Abutment portion 30 First return spring 31 Receiving member 32 Second return spring 33 Valve 34 Connection terminal 35 Coil winding 36 Yoke

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Claims (1)

Claims 1. A normally closed solenoid valve comprising: a coil unit having a coil wound around a bobbin; and a valve operating unit that is opened by energizing the coil unit. In the valve actuation unit, a first return spring and a second return spring having a higher spring load are inserted in series between the fixed core and the fixed core in this order via a buffer member, A movable core provided with a valve element; and a valve seat member provided with a valve element provided at the tip of the movable core. The movable core is attracted to the fixed core side by energizing the coil unit. The cushioning member contacts the fixed core against the spring load of the first return spring, and then the movable core moves the second retarder while the cushioning member remains in contact with the fixed core. Normally closed solenoid valves, characterized in that the opening in contact with said fixed core against the spring load of the spring.