Patent ID: 7896029

Claim:
A four-way valve comprising: a housing member including a valve chamber; a valve seat having a thickness and including a bearing surface portion located in said valve chamber; a first channel having an inside surface and acting as an outlet channel of a high-temperature fluid and a second channel having an inside surface and acting as an outlet channel of a low-temperature fluid, respectively, at a predetermined time, said first and second channels including openings adjacent to each other on said bearing surface portion of said valve seat, and passing through the thickness of said valve seat and extending outside of said valve chamber; a valve element that is movable with respect to said bearing surface portion of said valve seat; and a thermal resistor portion suppressing heat transfer between said first and second channels and located proximate the openings of said first and second channels, wherein said thermal resistor portion includes at least one gas retention layer-forming member having a ring shape and located on said inside surface of at least one of said first and second channels, proximate the openings of at least one of said first and second channels, and at least partially spaced from said inside surface of the corresponding channel so that a gas retention layer is formed between said gas retention layer-forming member and said inside surface of the respective channel, within the thickness of said valve seat, and each of the gas retention layer-forming members has a tapered funnel shape, having a larger diameter at a first end, the first end contacting the inside surface of the respective channel, at the opening of the respective channel, and a smaller diameter at a second end, the second end being spaced from the inside surface of the respective channel so that only the first end of the respective gas retention layer-forming member contacts the inside surface of the respective channel.