Multiple stage passive variable displacement vane pump
View Patent ↗The present invention is a multiple stage variable displacement vane pump comprising a pressure regulating spring guide. A first spring and a second spring may be controlled by said pressure regulating spring guide. The present invention does not require a solenoid or electronic control. Control of flow and speed is achieved through operable of the pressure regulating spring guide that causes the first spring and second spring to be operable in relation to one another, but for the first spring and the second spring to be operable independently of each other. The springs may be positioned to be inline in relation to each other. Rotation of a slide and pressure exerted thereby upon the pressure regulating spring guide may create a first spring regulation stage and a second spring regulation stage.
1. A variable displacement vane pump comprising:
a housing;
a rotor positioned within the housing;
vanes slidably coupled to the rotor;
a pivotable cam ring having an inner surface engaged by the vanes, wherein rotation of the cam ring varies an eccentricity of the cam ring relative to the rotor to vary the displacement of the pump;
a pressure regulating spring guide urging the cam ring toward a position of maximum eccentricity, the pressure regulating spring guide including first and second springs engaging a slidable shaft, the first spring engaging the cam ring and the second spring engaging the housing; and
a pressure chamber in receipt of pressurized fluid output by the pump to apply a force urging the cam ring toward a position of minimum eccentricity, wherein the pressure regulating spring guide includes a land portion separating and being engaged by the first and second springs.
2. The variable displacement vane pump of claim 1 , wherein the pressure regulating spring guide includes a flange fixed at an end of the shaft, the flange being positioned within a pocket of the housing to limit the range of axial travel of the shaft.
3. The variable displacement vane pump of claim 2 , wherein the second spring biases the flange into engagement with the housing when the cam ring is at the position of maximum eccentricity.
4. A variable displacement vane pump comprising:
a housing;
a rotor positioned within the housing;
vanes slidably coupled to the rotor;
a pivotable cam ring having an inner surface engaged by the vanes, wherein rotation of the cam ring varies an eccentricity of the cam ring relative to the rotor to vary the displacement of the pump;
a pressure regulating spring guide urging the cam ring toward a position of maximum eccentricity, the pressure regulating spring guide including first and second springs engaging a slidable shaft, the first spring engaging the cam ring and the second spring engaging the housing; and
a pressure chamber in receipt of pressurized fluid output by the pump to apply a force urging the cam ring toward a position of minimum eccentricity, wherein the first spring overhangs an end of the shaft while engaging the cam ring when the cam ring is in the position of maximum eccentricity.
5. The variable displacement vane pump of claim 4 , wherein the first and second springs are coaxially aligned with one another and axially spaced apart from each other.
6. The variable displacement vane pump of claim 5 , wherein the shaft extends through the first and second springs.
7. The variable displacement vane pump of claim 4 , further including first and second seals fixed for rotation with the cam ring and engaging the housing to at least partially define the pressure chamber.
8. A variable displacement vane pump comprising:
a housing;
a rotor positioned within the housing;
vanes slidably coupled to the rotor;
a pivotable cam ring having an inner surface engaged by the vanes, wherein rotation of the cam ring varies an eccentricity of the cam ring relative to the rotor to vary the displacement of the pump;
a pressure regulating spring guide urging the cam ring toward a position of maximum eccentricity, the pressure regulating spring guide including first and second springs and a slidable shaft, the slidable shaft including a flange biased into contact with the housing by the second spring when the cam ring is at the position of maximum eccentricity, the first spring engaging the cam ring and the second spring engaging the housing; and
a pressure chamber in receipt of pressurized fluid output by the pump to apply a force urging the cam ring toward a position of minimum eccentricity, wherein the flange is disengaged from contact with the housing when the cam ring is urged toward the position of minimum eccentricity.
9. The variable displacement vane pump of claim 8 , wherein the first spring overhangs an end of the shaft while engaging the cam ring when the cam ring is in the position of maximum eccentricity.
10. The variable displacement vane pump of claim 8 , wherein the first and second springs are coaxially aligned with one another.
11. The variable displacement vane pump of claim 10 , wherein the shaft extends through the first and second springs.
12. The variable displacement vane pump of claim 8 , further including first and second seals fixed for rotation with the cam ring and engaging the housing to at least partially define the pressure chamber.
13. The variable displacement vane pump of claim 8 , wherein the first spring includes a first spring rate different than a second spring rate of the second spring.
14. The variable displacement vane pump of claim 8 , wherein the second spring is preloaded in compression between the housing and the shaft when the cam ring is in the position of maximum eccentricity.
15. The variable displacement vane pump of claim 8 , wherein the flange is positioned at an end of the shaft.