Valve apparatus

A valve apparatus comprising:

• a housing that is configured to conduct a fluid through an inside of the housing;
• a passage hole forming portion that is placed in the housing and is not rotatable relative to the housing, wherein the passage hole forming portion has at least one passage hole which is configured to conduct the fluid through the at least one passage hole;
• a rotor that is placed in the housing on one axial side relative to the passage hole forming portion in an axial direction of a predetermined central axis of the rotor, wherein the rotor is configured to rotate about the predetermined central axis while sliding relative to the passage hole forming portion;
• and
• a differential pressure device that is placed on the one axial side relative to the rotor in the axial direction and has a pressure chamber which is configured to receive the fluid, wherein:
• the housing has:
• a one-side space that is placed on the one axial side relative to the rotor in the axial direction;
• and
• at least one other-side space that is placed on another axial side, which is opposite to the one axial side, relative to the passage hole forming portion in the axial direction, wherein the at least one other-side space is communicated with the at least one passage hole;
• the rotor is configured to increase or decrease an opening degree of the at least one passage hole relative to the one-side space in response to rotation of the rotor;
• the differential pressure device is configured to generate an urging force that urges the rotor against the passage hole forming portion by a differential pressure between a pressure in the pressure chamber and a pressure in the one-side space at least when a pressure in the at least one other-side space is higher than the pressure in the one-side space;
• the urging force is increased when the pressure in the pressure chamber is increased relative to the pressure in the one-side space;
• and
• a communication passage is formed to communicate between the at least one other-side space and the pressure chamber.

A valve apparatus comprising:

• a housing that is configured to conduct a fluid through an inside of the housing;
• a passage hole forming portion that is placed in the housing and is not rotatable relative to the housing, wherein the passage hole forming portion has at least one passage hole which is configured to conduct the fluid through the at least one passage hole;
• a rotor that is placed in the housing on one axial side relative to the passage hole forming portion in an axial direction of a predetermined central axis of the rotor, wherein the rotor is configured to rotate about the predetermined central axis while sliding relative to the passage hole forming portion;
• and
• a differential pressure device that is placed on the one axial side relative to the rotor in the axial direction and has a pressure chamber which is configured to receive the fluid, wherein:
• the housing has:
• a one-side space that is placed on the one axial side relative to the rotor in the axial direction;
• and
• at least one other-side space that is placed on another axial side, which is opposite to the one axial side, relative to the passage hole forming portion in the axial direction, wherein the at least one other-side space is communicated with the at least one passage hole;
• the rotor is configured to increase or decrease an opening degree of the at least one passage hole relative to the one-side space in response to rotation of the rotor;
• the differential pressure device is configured to generate an urging force that urges the rotor against the passage hole forming portion by a differential pressure between a pressure in the pressure chamber and a pressure in the one-side space at least when a pressure in the at least one other-side space is higher than the pressure in the one-side space;
• the urging force is increased when the pressure in the pressure chamber is increased relative to the pressure in the one-side space;
• the valve apparatus comprises a shaft that is placed in the housing and extends from the one axial side relative to the passage hole forming portion and the rotor to the another axial side relative to the passage hole forming portion and the rotor along the predetermined central axis, wherein the shaft has a pressure-chamber exposed portion that is exposed in the pressure chamber;
• a communication passage is formed at an inside of the shaft and is configured to communicate between the at least one other-side space and the pressure chamber;
• and
• the communication passage extends at the inside of the shaft in the axial direction from the one axial side relative to the passage hole forming portion and the rotor to the another axial side relative to the passage hole forming portion and the rotor, wherein the communication passage opens to the pressure chamber at the pressure-chamber exposed portion.