Hydrodynamic retarder system

1. A hydrodynamic retarder system for a vehicle comprising:

a. a fluid sump for housing a fluid and having a first volume of the fluid;

b. a pump for pumping the fluid from the fluid sump;

c. a retarder having a fluid chamber for housing a second volume of the fluid;

d. a second sump for housing at least a third volume of the fluid and fluidly connected to the fluid sump; the third volume of the fluid being substantially a same volume as the second volume of the fluid;

e. a retarder inlet valve fluidly connected to the fluid sump via the pump and movable between a closed position for directing fluid flow to the second sump and an open position for directing fluid flow to the retarder, the retarder inlet valve movable from the closed position to the open position when the retarder is activated; and

f. a passage valve actuatable between at least a first position allowing fluid flow from the second sump to the fluid sump and a second position preventing or restricting fluid flow from the second sump to the fluid sump, wherein the restricted fluid flow from the second sump to the fluid sump in the second position of the passage valve is smaller than the fluid flow from the second sump to the fluid sump in the first position of the passage valve;

wherein in a first operational state with the vehicle powered on and the retarder deactivated, the pump directs fluid flow from fluid sump to the retarder inlet valve being in the closed position and directing fluid flow to the second sump;

wherein in a second operational state with the vehicle on and the retarder activated, the retarder inlet valve moves to the open position directing fluid flow into the retarder and flowing out of the retarder after filling the second volume of the fluid and discharging to the second sump.

2. The hydrodynamic retarder system of claim 1 , wherein in the second operational state the passage valve is in the first position to allow fluid flow from the second sump to the fluid sump.

3. The hydrodynamic retarder system of claim 1 , wherein the second sump is fluidly connected to the fluid sump at least at an overflow opening positioned to allow the second sump to contain up to the third volume of the fluid.

4. The hydrodynamic retarder system of claim 3 , wherein in the first operational state the passage valve is in the second position allowing the second sump to fill until fluid discharges from the overflow opening, the vehicle is powered off or the retarder is activated.

5. The hydrodynamic retarder system of claim 1 , wherein the hydrodynamic retarder system is a hydrodynamic transmission and retarder system, and further comprising a transmission in fluid communication with the fluid sump, wherein the pump is additionally configured to pump fluid from the fluid sump through the transmission and back to the fluid sump.

6. The hydrodynamic retarder system of claim 5 , wherein the second sump includes a full partition wall separating the second sump into two fluid compartments, one of the two compartments having a volume about equal to the third volume of the fluid, and wherein when the passage valve is in the first position, the passage valve allows fluid flow from the one of the two compartments having the volume about equal to the third volume of the fluid to the fluid sump and prevents or restricts fluid flow between the two compartments and, when in the second position, the passage valve prevents or restricts fluid flow from the second sump to the fluid sump and allows fluid flow between the two compartments.

7. The hydrodynamic retarder system of claim 1 , wherein a second sump floor is sloped downwards and/or wherein a fluid sump floor is sloped downwards.

8. The hydrodynamic retarder system of claim 7 , further including a drain opening at a lowest point of the fluid sump floor and/or the second sump floor.

9. The hydrodynamic retarder system of claim 8 , further including a drain valve for opening and closing the drain opening.

10. The hydrodynamic retarder system of claim 9 , further including a restricted flow passage connecting the drain opening of the second sump with the fluid sump, the drain opening of the second sump allowing fluid in the second sump to drain or empty into the fluid sump via the restricted flow passage.

11. The hydrodynamic retarder system of claim 1 , wherein in a third operational state with the vehicle powered off, all the fluid of the hydrodynamic retarder system resides in the fluid sump.

12. The hydrodynamic retarder system of claim 1 , wherein the hydrodynamic retarder system is configured such that in the second operational state fluid flow from the second sump to the fluid sump has a flow rate that matches a flow rate of the fluid flow flowing into the retarder.

13. A hydrodynamic retarder system for a vehicle comprising:

a. a fluid sump for housing a fluid and having a first volume of the fluid;

b. a pump for pumping the fluid from the fluid sump;

c. a retarder having a fluid chamber for housing a second volume of the fluid;

d. a second sump for housing at least a third volume of the fluid and fluidly connected to the fluid sump; the third volume of the fluid being substantially a same volume as the second volume of the fluid; and

e. a retarder inlet valve fluidly connected to the fluid sump via the pump and movable between a closed position for directing fluid flow to the second sump and an open position for directing fluid flow to the retarder, the retarder inlet valve movable from the closed position to the open position when the retarder is activated;

wherein in a first operational state with the vehicle powered on and the retarder deactivated, the pump directs fluid flow from fluid sump to the retarder inlet valve being in the closed position and directing fluid flow to the second sump;

wherein in a second operational state with the vehicle on and the retarder activated, the retarder inlet valve moves to the open position directing fluid flow into the retarder and flowing out of the retarder after filling the second volume of the fluid and discharging to the second sump, and

wherein the second sump includes a partial wall for separating an upper portion of the fluid contained in a first partition space from a second partition space and allowing fluid communication at a lower portion of the fluid contained in the second sump and wherein fluid flow from the retarder inlet valve in the closed position or from the retarder flows to the first partition space and the second partition space includes a connection to the fluid sump.

14. The hydrodynamic retarder system of any of claim 13 , wherein the hydrodynamic retarder system is a hydrodynamic transmission and retarder system, and further comprising a transmission in fluid communication with the fluid sump, wherein the pump is additionally configured to pump fluid from the fluid sump through the transmission and back to the fluid sump.

15. The hydrodynamic retarder system of claim 13 , further including a drain opening at a lowest point of a fluid sump floor and/or a second sump floor.

16. A hydrodynamic retarder system for a vehicle comprising:

a. a fluid sump for housing a fluid and having a first volume of the fluid;

b. a pump for pumping the fluid from the fluid sump;

c. a retarder having a fluid chamber for housing a second volume of the fluid;

d. a second sump for housing at least a third volume of the fluid and fluidly connected to the fluid sump; the third volume of the fluid being substantially a same volume as the second volume of the fluid; and

e. a retarder inlet valve fluidly connected to the fluid sump via the pump and movable between a closed position for directing fluid flow to the second sump and an open position for directing fluid flow to the retarder, the retarder inlet valve movable from the closed position to the open position when the retarder is activated;

wherein in a first operational state with the vehicle powered on and the retarder deactivated, the pump directs fluid flow from fluid sump to the retarder inlet valve being in the closed position and directing fluid flow to the second sump;

wherein in a second operational state with the vehicle on and the retarder activated, the retarder inlet valve moves to the open position directing fluid flow into the retarder and flowing out of the retarder after filling the second volume of the fluid and discharging to the second sump, and

wherein the second sump is positioned at a height or a level above the fluid sump and/or the pump.

17. The hydrodynamic retarder system of claim 16 , wherein in the second operational state a passage valve is in an open position to allow fluid flow from the second sump to the fluid sump.

18. The hydrodynamic retarder system of claim 16 , further including a drain opening at a lowest point of a fluid sump floor and/or a second sump floor.

19. The hydrodynamic retarder system of claim 16 , further comprising a passage valve actuatable between at least a first position allowing fluid flow from the second sump to the fluid sump and a second position preventing or restricting fluid flow from the second sump to the fluid sump, wherein the restricted fluid flow from the second sump to the fluid sump in the second position of the passage valve is smaller than the fluid flow from the second sump to the fluid sump in the first position of the passage valve.