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A solenoid valve has a valve body with first and second ports. A bobbin is mounted to the valve body. A winding is wound on the bobbin. A stator is fitted to one end of a hole through the bobbin and defines a third port therein. A plunger is slidably fitted to the hole and movable between a normal p

A solenoid valve has a valve body with first and second ports. A bobbin is mounted to the valve body. A winding is wound on the bobbin. A stator is fitted to one end of a hole through the bobbin and defines a third port therein. A plunger is slidably fitted to the hole and movable between a normal position and an energized position. Two plugs are installed at respective ends of the plunger and arranged to selectively close the first and third ports. A flux return device is fixed to the stator and the bobbin. A spring returns the plunger from the energized position, where the plunger closes the third port and the first and second ports communicate with each other via the hole in the bobbin, to the normal position, where the plunger closes the first port and the second and third ports communicate with each.

대표청구항 ▼

1. A solenoid valve comprising: a valve body defining a first port and a second port isolated from the first port;a bobbin mounted to the valve body, the bobbin comprising:a tube portion;a connection portion formed at one end of the tube portion;a mounting portion extending from the connection porti

1. A solenoid valve comprising: a valve body defining a first port and a second port isolated from the first port;a bobbin mounted to the valve body, the bobbin comprising:a tube portion;a connection portion formed at one end of the tube portion;a mounting portion extending from the connection portion in a direction away from the tube portion and mounted to the valve body; anda hole axially extending through the tube portion, connection portion and mounting portion;a winding wound on the tube portion of the bobbin;a stator installed in one end of the hole in the bobbin remote from the mounting portion, the stator defining a third port therein;a plunger installed in the hole of the bobbin, the plunger having an outer circumferential surface and defining a void therein, the void being spaced from the outer circumferential surface;first and second plugs mounted at respective axial ends of the plunger;a flux return device fixed to the stator and the bobbin and configured for cooperating with the plunger and the stator to provide a path for magnetic flux generated by the winding; anda spring attached to the plunger and arranged to urge the plunger towards the valve body,wherein the plunger is slidably disposed within the hole in the bobbin and movable between a normal position, where the plunger is adjacent the valve body and the first plug closes the first port and the second port communicates with the third port via a passage, and an energized position where the plunger is adjacent the stator and the second plug closes the third port and the second port communicates with the first port via the hole in the bobbin;wherein, when energized, the winding moves the plunger against the urgings of the spring to the energized position;wherein the passage between the second port and the third port passes through the void of the plunger; andwherein the plunger comprises a body portion within which the void is formed, the body portion comprises a middle section and a air of end sections extending from respective ends of the middle section, a channel being formed between an inner surface of the bobbin and an outer surface of each of the end sections of the body portion, an opening being formed at a joint between the middle section and each of the end sections for communicating the void with a corresponding channel, the passage passing through the channels and the openings. 2. The solenoid valve of claim 1, wherein each of the end sections has an outer diameter less than that of the middle section. 3. The solenoid valve of claim 1, wherein the plunger further comprises a cap fixedly mounted around one of the end sections and the cap defines a through hole providing access to one of said plugs. 4. The solenoid valve of claim 1, wherein the bobbin is pivotably mounted to the valve body. 5. The solenoid valve of claim 4, wherein one of the mounting portion of the bobbin and the valve body defines an annular groove and the other of the mounting portion of the bobbin and the valve body defines a locking hole, a locking pin extends through the locking hole and is received in the annular groove. 6. The solenoid valve of claim 1, wherein a seal is provided between the mounting portion of the bobbin and the valve body, and another seal is provided between the bobbin and the stator. 7. The solenoid valve of claim 1, wherein at least one of the plugs is spring loaded by a second spring disposed within the void in the plunger to limit the contact force between said plug and the corresponding port. 8. A solenoid valve comprising: a valve body defining a first port and a second port isolated from the first port;a bobbin mounted to the valve body, the bobbin comprising: a tube portion; a connection portion formed at one end of the tube portion;a mounting portion extending from the connection portion in a direction away from the tube portion and mounted to the valve body; anda hole axially extending through the tube portion, connection portion and mounting portion;a winding wound on the tube portion of the bobbin;a stator installed in one end of the hole in the bobbin remote from the mounting portion, the stator defining a third port therein;a plunger defining a void therein;first and second plugs mounted at respective axial ends of the plunger;a flux return device fixed to the stator and the bobbin and configured for cooperating with the plunger and the stator to provide a path for magnetic flux generated by the winding; anda spring attached to the plunger and arranged to urge the plunger towards the valve body,wherein the plunger is slidably disposed within the hole in the bobbin and movable between a normal position, where the plunger is adjacent the valve body and the first plug closes the first port and the second port communicates with the third port via a passage, and an energized position where the plunger is adjacent the stator and the second plug closes the third port and the second port communicates with the first port via the hole in the bobbin;wherein, when energized, the winding moves the plunger against the urgings of the spring to the energized position; and wherein the passage between the second port and the third port passes through the void of the plunger; wherein the flux return device comprises:a U-shaped frame with a closed end and an open end, the stator being fixed to the closed end of the frame; anda flux plate having an outer side and an inner side, the outer side of the flux plate being fixed to the open end of the frame, the inner side of the flux plate being fixed to the connection portion of the bobbin by way of insert molding. 9. The solenoid valve of claim 8, wherein the flux plate defines a through hole through which the hole in the bobbin and material of the bobbin surrounding the hole extends, the through hole in the flux plate has an inner surface, the plunger having an outer surface facing the inner surface of the through hole, a distance between the outer surface of the plunger and the inner surface of the through hole of the flux plate being less than 1 mm. 10. The solenoid valve of claim 8, wherein the flux plate defines a plurality of through apertures through which material of the bobbin extends forming connection pins inter-connecting two parts of the connection portion of the bobbin located on opposite sides of the flux plate. 11. A solenoid valve comprising: a valve body defining a first port and a second port isolated from the first port;a bobbin mounted to the valve body, the bobbin comprising:a tube portion;a connection portion formed at one end of the tube portion;a mounting portion extending from the connection portion in a direction away from the tube portion and mounted to the valve body; anda hole axially extending through the tube portion, connection portion and mounting portion;a winding wound on the tube portion of the bobbin;a stator installed in one end of the hole in the bobbin remote from the mounting portion, the stator defining a third port therein;a plunger;first and second plugs mounted at respective axial ends of the plunger;a flux return device fixed to the stator and the bobbin and configured for cooperating with the plunger and the stator to provide a path for magnetic flux generated by the winding; anda spring attached to the plunger and arranged to urge the plunger towards the valve body,wherein the plunger is slidably disposed within the hole in the bobbin and movable between a normal position, where the plunger is adjacent the valve body and the first plug closes the first port and the second port communicates with the third port via a passage, and an energized position where the plunger is adjacent the stator and the second plug closes the third port and the second port communicates with the first port via the hole in the bobbin;wherein, when energized, the winding moves the plunger against the urgings of the spring to the energized position; andwherein the flux return device comprises a frame and a flux plate fixed to the frame, the stator is fixed to the frame, and the flux plate is fixed to the connection portion of the bobbin by insert molding; andwherein the flux plate defines a through hole through which the hole of the bobbin passes unbroken, the through hole has an inner surface, the plunger has an outer surface facing the through hole, and a distance between the outer surface of the plunger and the inner surface of the through hole of the flux plate is less than 1 mm. 12. The solenoid valve of claim 11, wherein the plunger comprises a body portion within which a void is formed, the body portion comprises a middle section and a pair of end sections extending from respective ends of the middle section, a channel being formed between an inner surface of the bobbin and an outer surface of each of the end sections, an opening being formed at a joint between the middle section and each of the end sections for communicating the void with a corresponding channel, the passage passing through the channels. 13. The solenoid valve of claim 12, wherein each of the end sections has an outer diameter less than that of the middle section. 14. The solenoid valve of claim 12, wherein the plunger further comprises a cap fixedly mounted around one of the end sections of the body portion adjacent the valve body, and the cap defines a through hole providing access to one of said plugs. 15. A solenoid valve comprising: a valve body defining a first port and a second port isolated from the first port;a bobbin pivotably mounted to the valve body, the bobbin comprising:a tube portion;a connection portion formed at one end of the tube portion;a mounting portion extending from the connection portion in a direction away from the tube portion and mounted to the valve body; anda hole axially extending through the tube portion, connection portion and mounting portion;a winding wound on the tube portion of the bobbin;a stator installed in one end of the hole in the bobbin remote from the mounting portion, the stator defining a third port therein;a plunger;first and second plugs mounted at respective axial ends of the plunger;a flux return device fixed to the stator and the bobbin and configured for cooperating with the plunger and the stator to provide a path for magnetic flux generated by the winding; anda spring attached to the plunger and arranged to urge the plunger towards the valve body,wherein the plunger is slidably disposed within the hole in the bobbin and movable between a normal position, where the plunger is adjacent the valve body and the first plug closes the first port and the second port communicates with the third port via a passage, and an energized position where the plunger is adjacent the stator and the second plug closes the third port and the second port communicates with the first port via the hole in the bobbin; andwherein, when energized, the winding moves the plunger against the urgings of the spring to the energized position,wherein the flux return device comprises a frame with an open end and a plate fixed to the open end of the frame, the stator is fixed to the frame; andwherein the plate defines a through hole through which the bobbin passes, the plate has an inner surface surrounding the through hole, the plunger has an outer surface facing the bobbin, and a distance between the outer surface of the plunger and the inner surface of the plate is less than 0.85 mm. 16. The solenoid valve of claim 15, wherein one of the bobbin and valve body defines an annular groove and the other of the bobbin and valve body defines a mounting hole, at least one locking pin extending through the mounting hole to be received in the groove. 17. The solenoid valve of claim 15, wherein the plunger comprises a body portion within which the void is formed, the body portion comprises a middle section and a pair of opposite end sections respectively extending from opposite ends of the middle section, a channel being formed between an inner surface of the bobbin and an outer surface of each of the opposite end sections of the body portion, an opening being formed at a joint between the body portion and each of the opposite ends for communicating the void with a corresponding channel, the passage passing through the channels. 18. The solenoid valve of claim 15, wherein the plate is fixed to the connection portion of the bobbin by insert molding.