A control valve assembly for a cooling system for an engine, comprising:
- a valve casing formed with a first port, a second port, a third port, and a fourth port;
- a first valve element and a first valve seat cooperating with said first valve element so as to open and close a first controlled aperture through said first valve seat, said first controlled aperture being on a first fluid flow path between said first port and said third port and being the only controlled aperture thereon, and also being on a third fluid flow path between said second port and said third port;
- a second valve element and a second valve seat cooperating with said second valve element so as to open and close a second controlled aperture through said second valve seat, said second controlled aperture being on a second fluid flow path between said first port and said fourth port;
- a third valve element and a third valve seat cooperating with said third valve element so as to open and close a third controlled aperture through said third valve seat, said third controlled aperture being on said third fluid flow path between said second port and said third port, said first and third controlled apertures being the only controlled apertures on said third fluid flow path between said second port and said third port;
- a fourth valve element and a fourth valve seat cooperating with said fourth valve element so as to open and close a fourth controlled aperture through said fourth valve seat, said fourth controlled aperture being on a fourth fluid flow path between said second port and said fourth port and being the only controlled aperture thereon, and said fourth controlled aperture also being on said second fluid flow path between said first port and said fourth port, said second and fourth controlled apertures being the only controlled apertures on said second fluid flow path between said first port and said fourth port;
- a first temperature sensitive actuator exposed to sense the temperature of the fluid conducted through said second port, which, when it senses a temperature less than a first predetermined temperature, moves said first valve element so as to press said first valve element against said first valve seat and so as to close said first controlled aperture through said first valve seat, interrupting communication between said first port and said third port via said first fluid flow path and between said second port and said third port via said third fluid flow path, and moves said second valve element so as to bring said second valve element away from said second valve seat and so as to open said second controlled aperture through said second valve seat, partially establishing communication between said first port and said fourth port via said second fluid flow path;
- and when it senses a temperature higher than said first predetermined temperature, moves said first valve element so as to bring said first valve element away from said first valve seat and so as to open said first controlled aperture through said first valve seat, establishing communication between said first port and said third port via said first fluid flow path and partially establishing communication between said second port and said third port via said third fluid flow path, and moves said second valve element so as to press said second valve element against said second valve seat and so as to close said second controlled aperture through said second valve seat, interrupting communication between said first port and said fourth port via said second fluid flow path;
- a second temperature sensitve actuator exposed to sense the temperature of the fluid conducted through said second port, which, when it senses a temperature less than a second predetermined temperature which is higher than said first predetermined temperature, moves said third valve element so as to press said third valve element against said third valve seat and so as to close said third controlled aperture through said third valve seat, interrupting communication between said second port and said third port via said third flow path, and moves said fourth valve element so as to bring said fourth valve element away from said fourth valve seat and so as to open said fourth controlled aperture through said fourth valve seat, establishing communication between said second port and said fourth port via said fourth fluid flow path and partially establishing communication between said first port and said fourth port via said second fluid flow path;
- and when it senses a temperature higher than said second predetermined temperature, moves said third valve element so as to bring said third valve element away from said third valve seat and so as to open said third controlled aperture through said third valve seat, partially establishing communication between said second port and said third port via said third fluid flow path, and moves said fourth valve element so as to press said fourth valve element against said fourth valve seat and so as to close said fourth controlled aperture through said fourth valve seat, interrupting communication between said second port and said fourth port via said fourth fluid flow path and interrupting communication between said first port and said fourth port via said second fluid flow path.