Reciprocating piston pump

1 . A pump system comprising:

a housing defining a first internal volume and a second internal volume;

a first piston positioned to separate the first internal volume into a first chamber and a second chamber;

a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber;

a first inlet check valve configured to be at least fluidly coupled to a gas spring, the first inlet check valve positioned to permit fluid flow from the gas spring into the first chamber;

a second inlet check valve configured to be at least fluidly coupled to the gas spring, the second inlet check valve positioned to permit fluid flow from the gas spring into the third chamber;

a directional control valve (DCV) repositionable between (a) a first position where the DCV is configured to fluidly couple the second chamber to a second fluid source and (b) a second position where the DCV is configured to fluidly couple the fourth chamber to the second fluid source; and

a relief valve configured to supply fluid to the DCV through an orifice to move the DCV from the first position to the second position.

2 . The pump system of claim 1 , wherein the first inlet check valve permits a first fluid received from the gas spring to enter the first chamber, and wherein the DCV fluidly couples the second chamber to a second fluid from the second fluid source.

3 . The pump system of claim 2 , wherein the first fluid is a gas, and the second fluid is a liquid.

4 . The pump system of claim 1 , wherein the relief valve is fluidly coupled to the second chamber through the orifice.

5 . The pump system of claim 1 , wherein the housing includes a divider separating the second chamber from the fourth chamber, the divider defining a piston rod aperture, wherein a piston rod extends between the first piston and the second piston such that a movement of the first piston causes an equal movement of the second piston, the piston rod extending through the piston rod aperture.

6 . The pump system of claim 1 , wherein the relief valve is fluidly coupled to the second chamber through a sensing line, and wherein the relief valve supplies fluid to the DCV through the orifice in response to a pressure within the sensing line exceeding a shift pressure to move the DCV from the first position to the second position.

7 . The pump system of claim 1 , further comprising:

a first outlet check valve fluidly coupled to the first chamber, the first outlet check valve configured to prevent fluid flow from the gas spring into the first chamber; and

a second outlet check valve fluidly coupled to the third chamber, the second outlet check valve configured to prevent fluid flow from the gas spring into the third chamber.

8 . The pump system of claim 7 , wherein the first outlet check valve is configured to permit fluid flow out of the first chamber when a pressure within the first chamber exceeds a threshold pressure of the first outlet check valve.

9 . The pump system of claim 1 , wherein the first inlet check valve is configured to prevent fluid flow out of the first chamber when a pressure within the first chamber exceeds a threshold pressure of the first inlet check valve.

10 . The pump system of claim 1 , wherein the first inlet check valve is directly fluidly coupled to the first chamber throughout an entire range of motion of the first piston, and wherein the second inlet check valve is directly fluidly coupled to the third chamber throughout the entire range of motion of the second piston.

11 . The pump system of claim 1 , wherein the housing defines a first outlet passage fluidly coupled to the first chamber and a second outlet passage fluidly coupled to the third chamber, and wherein the first outlet passage is fluidly coupled to the second outlet passage.

12 . A vehicle comprising:

a first reservoir configured to store a first fluid;

a second reservoir configured to store a second fluid at a high pressure; and

a pump system comprising:

a housing defining a first internal volume and a second internal volume;

a first piston positioned to separate the first internal volume into a first chamber and a second chamber;

a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, wherein the first chamber and the third chamber are configured to receive the first fluid at a low pressure, and the second chamber and the fourth chamber are configured to receive the second fluid;

a directional control valve (DCV) repositionable between (a) a first position where the DCV is configured to fluidly couple the second chamber to the second reservoir and (b) a second position where the DCV is configured to fluidly couple the fourth chamber to the second reservoir; and

a relief valve configured to supply the second fluid through an orifice to move the DCV between the first position and the second position in response to a pressure at a point between the relief valve and the orifice reaching a preset shift pressure, wherein the first reservoir comprises a gas spring.

13 . The vehicle of claim 12 , further comprising:

a chassis; and

a wheel-end assembly coupled to the chassis, the wheel-end assembly comprising a gas spring and a hydraulic damper, the gas spring configured to control a ride height of the vehicle based on providing or removing the first fluid from the gas spring.

14 . The vehicle of claim 12 , wherein the DCV is configured to fluidly couple the first reservoir to the fourth chamber in the first position, wherein the DCV is configured to fluidly couple the first reservoir to the second chamber in the second position, and wherein when the second fluid is supplied to the second chamber or the fourth chamber, the first fluid is forced out of one of the first chamber or the third chamber at a high pressure by one of the first piston or the second piston and into the gas spring.

15 . The vehicle of claim 12 , wherein the relief valve is fluidly coupled to the second chamber through the orifice.

16 . The vehicle of claim 12 , wherein the relief valve is a first relief valve, further comprising a second relief valve fluidly configured to supply the second fluid to the DCV to move the DCV between the second position and the first position.

17 . The vehicle of claim 12 , wherein the relief valve is fluidly coupled to the second chamber through a sensing line, and wherein the relief valve supplies the second fluid to the DCV through the orifice in response to a pressure within the sensing line exceeding the preset shift pressure to move the DCV from the first position to the second position.

18 . A pump system comprising:

a housing defining a first internal volume and a second internal volume;

a first piston positioned to separate the first internal volume into a first chamber and a second chamber;

a second piston positioned to separate the second internal volume into a third chamber and a fourth chamber, wherein the first chamber and the third chamber are configured to receive fluid flow from a gas spring at a low pressure, and the second chamber and the fourth chamber are configured to receive fluid flow from a high pressure fluid source;

a directional control valve (DCV) fluidly coupled to the second chamber and the fourth chamber;

a relief valve fluidly coupled to the DCV via a control line and the second chamber via a sensing line, the relief valve configured to open at a shift pressure; and

an orifice positioned along the sensing line, wherein the orifice is positioned to cause a delay in fluid flow along the sensing line, such that a pressure within the second chamber exceeds the shift pressure when a pressure at a point between the relief valve and the orifice reaches the shift pressure.

19 . The pump system of claim 18 , wherein the DCV is repositionable between (a) a first position where the DCV fluidly couples the second chamber to a reservoir, the reservoir providing a first fluid, and (b) a second position where the DCV fluidly couples the fourth chamber to the reservoir.

20 . The pump system of claim 18 , wherein the DCV is repositionable between (a) a first position where the DCV fluidly couples the fourth chamber to the high pressure fluid source providing a second fluid, and (b) a second position where the DCV fluidly couples the second chamber to the high pressure fluid source.