Hydraulic control system for an automatic transmission

1. A hydraulic control system for a transmission, the hydraulic control system comprising:

a pressure regulator subsystem with a source of pressurized hydraulic fluid for providing a flow of hydraulic fluid;

a transmission range selection control subsystem including a set of four valve assemblies actuated by a pair of solenoids; and

a clutch control subsystem that provides pressurized hydraulic fluid to a plurality of clutch actuators activated by a plurality of variable force solenoids through a plurality of valve assemblies,

wherein the plurality of valve assemblies of the clutch control subsystem are in fluid communication with the transmission range selection control subsystem and wherein the transmission range selection control subsystem employs the pressurized hydraulic fluid to engage a range selection through the clutch control subsystem.

2. The hydraulic control system of claim 1 wherein the source of pressurized hydraulic fluid is a pump.

3. The hydraulic control system of claim 1 wherein the set of four valve assemblies of the transmission range selection control subsystem includes a convertor fault valve assembly, an enabler valve assembly, a manual valve assembly, and a default mode valve assembly.

4. The hydraulic control system of claim 3 wherein each of the convertor fault valve assembly, enabler valve assembly, and the default mode valve assembly includes a spring and a valve slidably disposed in a bore, each of the convertor fault valve assembly, enabler valve assembly, and the default mode valve assembly being actuated by its respective spring and the pair of solenoids.

5. The hydraulic control system of claim 1 wherein each of the plurality of valve assemblies of the clutch control subsystem includes a spring and a valve slidably disposed in a bore.

6. The hydraulic control system of claim 5 wherein one of the plurality of valve assemblies of the clutch control subsystem is actuated by its respective spring and the pair of solenoids.

7. The hydraulic control system of claim 6 wherein each of the other valve assemblies of the plurality of valve assemblies is actuated by its respective spring and a respective solenoid of the plurality of variable force solenoids.

8. The hydraulic control system of claim 7 wherein the other valve assemblies of the plurality of valve assemblies includes five valve assemblies.

9. The hydraulic control system of claim 1 wherein the plurality of clutch actuators includes five clutch actuators.

10. The hydraulic control system of claim 1 wherein the clutch control subsystem includes at least one one-way check valve associated with one of the plurality of valve assemblies.

11. The hydraulic control system of claim 10 wherein the transmission range selection control subsystem includes a default mode valve assembly and wherein the one-way check valve communicates with the default mode valve assembly of the transmission range selection control subsystem.

12. The hydraulic control system of claim 11 wherein the clutch control subsystem includes a second one-way check valve associated with two other valve assemblies of the plurality of valve assemblies, the second one-way check valve being in communication with the default mode valve assembly.

13. A hydraulic control system for a transmission, the hydraulic control system comprising:

a pressure regulator subsystem with a source of pressurized hydraulic fluid for providing a flow of hydraulic fluid;

a cooler control flow subsystem that cools the hydraulic fluid;

a lubrication control subsystem that regulates lubrication fluid pressure as a function of the pressure of the hydraulic fluid;

a torque convertor control subsystem that modulates pressure to a torque convertor clutch;

a transmission range selection control subsystem including a set of four valve assemblies actuated by a boost solenoid and a default solenoid; and

a clutch control subsystem that provides pressurized hydraulic fluid to a plurality of clutch actuators activated by a plurality of variable force solenoids through a plurality of valve assemblies,

wherein the plurality of valve assemblies of the clutch control subsystem are in fluid communication with the transmission range selection control subsystem and wherein the transmission range selection control subsystem employs the pressurized hydraulic fluid to engage a range selection through the clutch control subsystem.

14. The hydraulic control system of claim 13 wherein the set of four valve assemblies of the transmission range selection control subsystem includes a convertor fault valve assembly, an enabler valve assembly, a manual valve assembly, and a default mode valve assembly.

15. The hydraulic control system of claim 14 wherein each of the convertor fault valve assembly, the enabler valve assembly, and the default mode valve assembly includes a spring and a valve slidably disposed in a bore, each of the convertor fault valve assembly, enabler valve assembly, and the default mode valve assembly being actuated by its respective spring and the boost and default solenoids.

16. The hydraulic control system of claim 15 wherein the clutch control subsystem includes a first one way check valve associated with one of the plurality of valve assemblies and a second one-way check valve associated with two other valve assemblies of the plurality of valve assemblies, the first one-way check valve and the second one-way check valve being in communication with the default mode valve assembly.