Patent ID: 6823897
Filing Date: 2004-11-30
Classification: F16K,F25B,Y10T

Abstract:
A four-way switching valve for switching between a first state in which a fluid introduced into a first port is discharged to a second port and the fluid introduced into a third port is discharged to a fourth port, and a second state in which the fluid introduced into the first port is discharged to the third port and the fluid introduced into the second port is discharged to the fourth port,the four-way switching valve comprising a combination of: a first three-way switching valve for carrying out a switching operation to cause the second port to communicate with the first port or the fourth port; and a second three-way switching valve for carrying out a switching operation to cause the third port to communicate with the fourth port or the first port; wherein the first three-way switching valve includes a first valve element for opening and closing respective passages formed between the second port and the first port and between the second port and the fourth port, and a first piston for driving the first valve element in a direction in which the passage formed between the second port and the first port is closed, and wherein the second three-way switching valve includes a second valve element for opening and closing respective passages formed between the third port and the first port and between the third port and the fourth port, and a second piston for driving the second valve element in a direction in which the passage formed between the third port and the first port is closed; and wherein the four-way switching valve further includes passage-switching means for selectively connecting a pressure-regulating chamber for the first piston to a chamber communicating with the fourth port or a chamber communicating with the first port; communication means for causing a pressure-regulating chamber for the second piston and a chamber communicating with the second port to communicate with each other; first and second guides which are slidably inserted into the respective passages formed between the second port and the first port and between the second port and the fourth port, for guiding the first valve element, and simultaneously close both of these passages at respective intermediate positions of the first three-way switching valve and the second three-way switching valve during switching operations thereof; and third and fourth guides which are slidably inserted into the respective passages formed between the third port and the first port and between the third port and the fourth port, for guiding the second valve element, and simultaneously closing both of these passages at the intermediate positions of the first three-way switching valve and the second three-way switching valve during the switching operations thereof, the first port and the fourth port being prevented from communicating with each other during the switching operations of the first three-way switching valve and the second three-way switching valve.