Abstract: In a pressure increase control valve, the size of a gap G between a plunger and a guide is 0.2 mm or greater, or a ratio between a diameter of a restriction and a seat diameter ds is 0.9 or less. Setting the size of the gap between the plunger and the guide to 0.2 mm or greater can decrease variations in an electromagnetic force with respect to a stroke of a valve body. In addition, setting the ratio between the diameter do of the restriction and the seat diameter to 0.9 or less can increase variations in a fluid force with respect to the stroke of the valve body. Therefore, it is easier to achieve a relationship between the electromagnetic force and a resistance force that is required in order to enable linear control of a differential pressure amount generated between upstream and downstream flows.

Abstract: In a pressure increase control valve, the size of a gap G between a plunger and a guide is 0.2 mm or greater, or a ratio between a diameter of a restriction and a seat diameter ds is 0.9 or less. Setting the size of the gap between the plunger and the guide to 0.2 mm or greater can decrease variations in an electromagnetic force with respect to a stroke of a valve body. In addition, setting the ratio between the diameter do of the restriction and the seat diameter to 0.9 or less can increase variations in a fluid force with respect to the stroke of the valve body. Therefore, it is easier to achieve a relationship between the electromagnetic force and a resistance force that is required in order to enable linear control of a differential pressure amount generated between upstream and downstream flows.

Abstract: According to the present invention, a cylindrical member of a solenoid valve is provided with a protruding portion that protrudes in an axial direction of the cylindrical member. By fitting the protruding portion into a vertical groove of a plunger, it is possible to restrict the cylindrical member from moving in a peripheral direction of the plunger. Therefore, it is possible to prevent change of the flow path that passes the plunger and the vertical groove, as well as to prevent variation in a sliding speed of the plunger or the like. As a result, a fluid pulsation reduction effect is obtained.

Abstract: According to the present invention, a cylindrical member of a solenoid valve is provided with a protruding portion that protrudes in an axial direction of the cylindrical member. By fitting the protruding portion into a vertical groove of a plunger, it is possible to restrict the cylindrical member from moving in a peripheral direction of the plunger. Therefore, it is possible to prevent change of the flow path that passes the plunger and the vertical groove, as well as to prevent variation in a sliding speed of the plunger or the like. As a result, a fluid pulsation reduction effect is obtained.

Abstract: The electromagnetic valve is comprised of first communication path and second communication path with a throttle connected in parallel to each other, a first plunger having a first valve for interrupting/communicating the first communication path and having a penetration hole extending to the second communication path, a second plunger having a second valve movable in or through the penetration hole for interrupting/communicating the second communication path, a spring member for generating spring biasing force and a coil member for generating an electromagnetic attracting force, when energized, to have the first and second plungers come close to each other against the spring biasing force. The electromagnetic valve may be controlled in a manner that the first communication path is interrupted and the second communication path is communicated at a pressure-increase timing during an anti-skid control.

Abstract: An electromagnetic valve is arranged in a conduit between a master cylinder and an intake side of a pump in a brake control system. In the electromagnetic valve, a main communication path and a restricted communication path are formed. The main communication path is alternatively opened and closed by a main valve body. The restricted communication path is formed in the main valve body and alternatively opened and closed by an auxiliary valve body. A solenoid generates electromagnetic force to bias the auxiliary valve body in a direction of opening the restricted communication path. The auxiliary valve body is provided with an engaging portion for engaging with the main valve body to move the main valve body in a direction of opening the main communication path after opening the restricted communication path.

Abstract: A wheel cylinder and brake piston are formed in the brake caliper of each wheel of a vehicle. A piezoelectric device, which is formed of laminated piezoelectric elements, is formed in the brake caliper such that it is connected with the wheel cylinder. By applying a voltage to the piezoelectric elements the piston device is made to expand and contract to thereby vary the volume of the wheel cylinder. Brake fluid is supplied from the master cylinder to the wheel cylinder via fluid passage formed in the brake caliper and a control valve for opening and closing this passage is formed in the passage. When there is a high pressure in the wheel cylinder, the piezoelectric device expands and the control valve closes. Then, by lowering the voltage the piezoelectric device contracts and the pressure in the wheel cylinder decreases.