High pressure liquid pump apparatus and pumping method

• US 5,322,418 A
• Filed: 11/19/1992
• Issued: 06/21/1994
• Est. Priority Date: 11/19/1992
• Status: Expired due to Fees

• Current Assignee: Toro Company (Toro)
• Original Assignee: Toro Company (Toro)
• Inventors: Comer, Robert C.
• Primary Examiner(s): Bennet, Henry A.
• Assistant Examiner(s): MCANDREWS JR, ROLAND G
• Application Number:
  US07/978,851
• Time in Patent Office: 579 Days
• Field of Search: 417/53, 417/364, 417/490, 417/466, 417/465, 417/486, 222/389, 222/340, 239/99, 239/101, 111/127
• US Class Current: 417/53
• CPC Class Codes: A01C 23/028 Contactless injection into the soil
• CPC Class Codes: B05B 9/0413 with reciprocating pumps, e.g. membrane pump, piston pump, bellow pump B05B9/0409 takes precedence
• CPC Class Codes: F04B 19/003 free-piston type pumps
• CPC Class Codes: F04B 19/22 of reciprocating-piston type
• CPC Class Codes: F04B 9/042 the means being cams
• CPC Class Codes: F04B 9/127 rectilinear movement of the pumping member in the working direction being obtained by a single-acting elastic-fluid motor, e.g. actuated in the other direction by gravity or a spring

Abstract

A liquid pumping apparatus and pump method is provided in which a reciprocal drive piston is carried in a pump body and is reciprocated back and forth by a mechanical power source such as a crankshaft. The pump body has a pump chamber which receives the liquid to be pumped. A pump piston which is separate from the drive piston is operatively connected to the pump chamber to expand and contract the volume of the pump chamber to first fill the pump chamber with liquid and then expel the liquid from the pump chamber in a pumping action. The pump piston is coupled to the drive piston for movement therewith during a portion of a pump cycle such that the drive piston is effective to move the pump piston in its volume expanding direction relative to the pump chamber at a first speed. Then, the connection between the pump piston and drive piston is broken and the pump piston is accelerated in its volume contracting direction to a second substantially faster speed to pump the liquid out of the pump chamber.

Claims

1. A liquid pump apparatus for pumping a liquid at an increased pressure, wherein the apparatus is driven by a motive means that provides a source of power for the liquid pumping action, which comprises:

(a) a pump body having a pump chamber which is suited to be filled with the liquid that is to be pumped, the pump chamber having inlet means for admitting the liquid to the pump chamber and outlet means for allowing the liquid to exit from the pump chamber;

(b) a movable pump means operatively connected to the pump chamber for expanding and contracting the volume of the pump chamber as the pump means is moved;

(c) valve means associated with the inlet means and the outlet means for allowing the liquid to flow into the pump chamber through the inlet means when the pump means is moved in a direction in which the pump chamber is expanded and for allowing the liquid to be pumped out of the pump chamber through the outlet means when the pump means is moved in a direction in which the pump chamber is contracted;

(d) a drive means operatively connected to the motive means for operation over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber, wherein the drive means is separate from the pump means such that the pump means can move independently from the drive means over at least a portion of the movement of the pump means;

(e) means for operatively transmitting the movement of the drive means to the pump means during a portion of each pump cycle such that the transmitted motion moves the pump means at a first speed in the direction in which the pump chamber volume is expanded to fill the pump chamber with liquid; and

(f) means for uncoupling the motion transmitting means between the pump means and the drive means after the pump chamber volume has been expanded and filled with liquid and for then accelerating the pump means to a second speed which is faster than the first speed in a direction in which the pump chamber volume is contracted to pump the liquid out of the pump chamber at the increased pressure, wherein the uncoupling and accelerating means comprises;

(i) means operatively connected to the pump means for storing energy and for supplying such energy against the pump means at a location which is suitable to drive the pump means in the direction in which the pump chamber volume is contracted; and

(ii) valve means, carried on the drive means, for periodically allowing at least some of the energy stored in the energy storing means to be applied to the pump means.

2. A liquid pump apparatus for pumping a liquid at an increased pressure, wherein the apparatus is driven by a motive means that provides a source of power for the liquid pumping action, which comprises:

(a) a pump body having a pump chamber which is suited to be filled with the liquid that is to be pumped, the pump chamber having inlet means for admitting the liquid to the pump chamber and outlet means for allowing the liquid to exit from the pump chamber;

(b) a movable pump means operatively connected to the pump chamber for expanding and contracting the volume of the pump chamber as the pump means is moved, wherein the pump means comprises a pump piston which is reciprocally contained in an elongated pump bore in the pump body;

(c) valve means associated with the inlet means and the outlet means for allowing the liquid to flow into the pump chamber through the inlet means when the pump means is moved in a direction in which the pump chamber is expanded and for allowing the liquid to be pumped out of the pump chamber through the outlet means when the pump means is moved in a direction in which the pump chamber is contracted;

(d) a drive means operatively connected to the motive means for operation over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber, wherein the drive means is separate from the pump means such that the pump means can move independently from the drive means over at least a portion of the movement of the pump means, wherein the drive means comprises a drive piston that is reciprocally contained in an elongated drive bore in the pump body, and wherein the pump bore and the drive bore are separate from one another such that the pump piston and the drive piston reciprocate along different axes;

(e) means for operatively transmitting the movement of the drive means to the pump means during a portion of each pump cycle such that the transmitted motion moves the pump means at a first speed in the direction in which the pump chamber volume is expanded to fill the pump chamber with liquid; and

(f) means for uncoupling the motion transmitting means between the pump means and the drive means after the pump chamber volume has been expanded and filled with liquid and for then accelerating the pump means to a second speed which is faster than the first speed in a direction in which the pump chamber volume is contracted to pump the liquid out of the pump chamber at the increased pressure.

3. A liquid pump apparatus for pumping a liquid at an increased pressure, wherein the apparatus is driven by a motive means that provides a source of power for the liquid pumping action, which comprises:

(a) a pump body having a pump chamber which is suited to be filled with the liquid that is to be pumped, the pump chamber having inlet means for admitting the liquid to the pump chamber and outlet means for allowing the liquid to exit from the pump chamber;

(b) a movable pump means operatively connected to the pump chamber for expanding and contracting the volume of the pump chamber as the pump means is moved;

(c) valve means associated with the inlet means and the outlet means for allowing the liquid to flow into the pump chamber through the inlet means when the pump means is moved in a direction in which the pump chamber is expanded and for allowing the liquid to be pumped out of the pump chamber through the outlet means when the pump means is moved in a direction in which the pump chamber is contracted;

(d) a drive means operatively connected to the motive means for operation over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber, wherein the drive means is separate from the pump means such that the pump means can move independently from the drive means over at least a portion of the movement of the pump means;

(e) means for operatively transmitting the movement of the drive means to the pump means during a portion of each pump cycle such that the transmitted motion moves the pump means at a first speed in the direction in which the pump chamber volume is expanded to fill the pump chamber with liquid; and

(f) means for uncoupling the motion transmitting means between the pump means and the drive means after the pump chamber volume has been expanded and filled with liquid and for then accelerating the pump means to a second speed which is faster than the first speed in a direction in which the pump chamber volume is contracted to pump the liquid out of the pump chamber at the increased pressure, wherein the uncoupling and accelerating means comprises;

(i) means operatively connected to the pump means for storing energy and for supplying such energy against the pump means at a location which is suitable to drive the pump means in the direction in which the pump chamber volume is contracted, wherein the energy storing means comprises a closed gas reservoir filled with a gas; and

(ii) control means for periodically allowing at least some of the energy stored in the energy storing means to be applied to the pump means.

4. The liquid pump apparatus of claim 3, wherein a portion of the pump means is operatively connected to the gas reservoir to compress the gas within the reservoir as the pump means moves in its volume expanding direction, whereby the compression of the gas increases the energy stored in the gas reservoir as the pump means fills the pump chamber with the liquid so that such stored energy is thereafter available to act against the pump means and drive the pump means in its volume contracting direction.

5. The liquid pump apparatus of claim 4, wherein the pump means comprises a pump piston that is reciprocally contained in an elongated pump bore in the pump body, wherein the pump bore has opposed first and second ends and the pump piston has opposed first and second faces, wherein the pump chamber comprises that portion of the pump bore which is formed between a first end of the pump bore and a first face of the pump piston, and wherein the gas reservoir is operatively connected to that portion of the pump bore which is formed between the opposed second end of the pump bore and the opposed second face of the pump piston.

6. A liquid pump apparatus for pumping a liquid at an increased pressure, wherein the apparatus is driven by a motive means that provides a source of power for the liquid pumping action, which comprises:

(a) a pump body having a pump chamber which is suited to be filled with the liquid that is to be pumped, the pump chamber having inlet means for admitting the liquid to the pump chamber and outlet means for allowing the liquid to exit from the pump chamber;

(b) a movable pump means operatively connected to the pump chamber for expanding and contracting the volume of the pump chamber as the pump means is moved, wherein the pump means comprises a reciprocal pump piston;

(c) valve means associated with the inlet means and the outlet means for allowing the liquid to flow into the pump chamber through the inlet means when the pump means is moved in a direction in which the pump chamber is expanded and for allowing the liquid to be pumped out of the pump chamber through the outlet means when the pump means is moved in a direction in which the pump chamber is contracted;

(d) a drive means operatively connected to the motive means for operation over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber, wherein the drive means is separate from the pump means such that the pump means can move independently from the drive means over at least a portion of the movement of the pump means, wherein the drive means comprises a reciprocal drive piston which is coaxial with the pump piston;

(e) means for operatively transmitting the movement of the drive means to the pump means during a portion of each pump cycle such that the transmitted motion moves the pump means at a first speed in the direction in which the pump chamber volume is expanded to fill the pump chamber with liquid, wherein the motion transmitting means comprises a seal formed of a relatively incompressible fluid trapped between the drive piston and the pump piston such that movement of the drive piston pulls the pump piston with it to operatively couple the pump piston to the drive piston; and

(f) means for uncoupling the motion transmitting means between the pump means and the drive means after the pump chamber volume has been expanded and filled with liquid and for then accelerating the pump means to a second speed which is faster than the first speed in a direction in which the pump chamber volume is contracted to pump the liquid out of the pump chamber at the increased pressure.

7. The liquid pump apparatus of claim 6, wherein the accelerating means comprises means operatively connected to the pump piston for storing energy and for supplying such energy against the pump piston at a location which is suitable to drive the pump piston in the direction in which the pump chamber volume is contracted, and further including control means for periodically allowing at least some of the energy stored in the energy storing means to be applied to the pump piston after the pump chamber volume has been expanded and filled with liquid.

8. The liquid pump apparatus of claim 7, wherein the control means includes valve means for breaking the fluid seal between the drive piston and the pump piston at some point in the movement of the drive piston to free the pump piston and allow the energy stored in the energy storing means to accelerate the pump piston away from the drive piston in its volume contracting direction.

9. The liquid pump apparatus of claim 8, wherein the pump piston is reciprocally contained in an elongated pump bore in the pump body, wherein the pump bore and the drive bore comprise a single, common drive/pump bore in the pump body such that the pump piston and the drive piston reciprocate along the same axis, wherein the valve means includes a fluid bleed passage formed on the drive piston and operatively communicating with the fluid trapped between the pump piston and the drive piston, wherein the fluid bleed passage is normally sealed against an inner diameter of the drive/pump bore, and further including a valve portion of greater diameter located at a predetermined location along the drive/pump bore which valve portion registers with the fluid bleed passage at a particular spot in the movement of the drive piston to allow additional fluid contained in the drive/pump bore to enter into the volume between the pump piston and the drive piston, thus breaking the fluid seal between the pump piston and the drive piston.

10. The liquid pump apparatus of claim 8, wherein the relatively incompressible fluid comprises oil.

11. The liquid pump apparatus of claim 8, further including means for reestablishing the fluid seal between the drive piston and the pump piston to reattach the pump piston to the drive piston for movement therewith in the next pump cycle.

12. The liquid pump apparatus of claim 11, wherein the pump piston includes a stem which is telescopically received in a fluid filled socket located in a lower end of the drive piston at the conclusion of the downstroke of the drive piston, and wherein the fluid seal reestablishing means comprises a pressure relief passage and fluid check valve means for opening and letting sufficient fluid to escape from between the pump piston and the drive piston as the drive piston approaches the pump piston to allow the stem to be received in the socket, wherein the check valve is configured to close to prevent further fluid escape while there is some fluid trapped between the pump piston and the drive piston to reestablish the fluid seal between the two.

13. A liquid pump apparatus for pumping an incompressible liquid, which comprises:

(a) a reciprocal piston assembly which is operatively connected to a motive means for reciprocating the piston assembly over a plurality of pump cycles with a single pump cycle comprising an upstroke and a downstroke of the piston assembly;

(b) a pump body having a pump chamber in which one end of the piston assembly is received for reciprocal movement towards and away from one end of the pump chamber;

(c) liquid inlet means leading to the pump chamber for allowing liquid to enter and fill the pump chamber as the one end of the piston assembly is moved away from the one end of the pump chamber and liquid outlet means leading from the pump chamber for allowing liquid to exit the pump chamber as the one end of the piston assembly is moved towards the one end of the pump chamber to pump the liquid out of the pump chamber;

(d) wherein the one end of the piston assembly is formed of two parts comprising a drive piston and a coaxial pump piston, wherein the drive piston is connected to the motive means and the pump piston is separate from the drive piston and is not directly coupled to the motive means, wherein the drive piston and the pump piston are spaced apart by a fluid receiving volume;

(e) means for coupling the pump piston to the drive piston during that stroke of the piston assembly in which the one end of the piston assembly is moved away from the one end of the pump chamber to fill the pump chamber with liquid, wherein the coupling means comprises a seal formed by a relatively incompressible fluid trapped in the fluid receiving volume between the pump piston and the drive piston; and

(f) means for releasing the pump piston from the drive piston after the pump chamber has been filled with liquid to allow the pump piston to be accelerated away from the drive piston back towards the one end of the pump chamber to pump the liquid contained in the pump chamber out of the pump chamber, whereby only the mass of the pump piston has to be accelerated to pump the liquid out of the pump chamber.

14. The liquid pump apparatus of claim 13, wherein the motive means comprises a rotary crankshaft such that the rotary motion of the crankshaft is converted to a reciprocal action of the piston assembly, wherein one revolution of the crankshaft is converted to a single pump single comprising an upstroke and a downstroke of the piston assembly.

15. The liquid pump apparatus of claim 13, wherein the drive piston has a first end and the pump piston has opposed first and second faces, wherein the pump piston second face acts on the liquid in the pump chamber to pump the liquid out of the pump chamber as the pump piston is accelerated towards the one end of the pump chamber, wherein the first face of the pump piston is generally adjacent the first end of the drive piston but is spaced therefrom by the fluid receiving volume, and wherein the coupling means comprises a seal formed by oil trapped in the fluid receiving volume between the first face of the pump piston and the first end of the drive piston such that the fluid receiving volume comprises an oil receiving volume.

16. The liquid pump apparatus of claim 15, wherein the drive piston has oil flow bleed means connecting the oil receiving volume between the drive piston and the pump piston to a supply of oil contained in the pump body around the drive piston, wherein the oil flow bleed means is normally closed to keep the oil seal intact between the pump piston and the drive piston during movement of the pump piston in its volume expanding direction, and further including valve means for opening the oil flow bleed means at the appropriate moment to allow oil to bleed into the oil receiving volume between the pump piston and drive piston to break the oil seal and release the pump piston from the drive piston.

17. The liquid pump apparatus of claim 16, wherein the valve means is carried on the drive piston and is contained in the oil containing area of the pump body.

18. The liquid pump apparatus of claim 16, further including a gas reservoir containing a gas operatively connected to the oil containing area of the pump body, wherein such gas within the reservoir is compressed during the motion of the piston assembly in that stroke which fills the pump chamber with the liquid with such compression serving to increase the energy stored in the gas, and further including passage means for allowing the stored energy in the gas to be applied to the pump piston after the oil seal is broken to accelerate the pump piston at a rate sufficiently fast to pump the liquid out of the pump chamber at an increased pressure.

19. A liquid pump apparatus for pumping an incompressible liquid, which comprises:

(a) a reciprocal piston assembly which is operatively connected to motive means for reciprocating the piston assembly, wherein the piston assembly includes a drive piston and a pump piston with the drive piston being connected to the motive means and the pump piston being separate from the drive piston such that it is not directly coupled to the motive means, and wherein a fluid receiving volume is located between the pump piston and the drive piston;

(b) a pump body in which the piston assembly is received, the pump body having a pump chamber into which the liquid is first drawn and from which the liquid is then pumped as the piston assembly reciprocates back and forth in the pump body in first and second directions;

(c) means for coupling the pump piston to the drive piston when the piston assembly is moved in the first direction to fill the pump chamber with liquid, wherein the coupling means comprises a seal formed by a relatively incompressible fluid trapped in the fluid receiving volume between the pump piston and the drive piston; and

(d) means for releasing the pump piston from the drive piston after the pump chamber has been filled with the liquid to allow the pump piston to move in the second direction independently from the drive piston to pump the liquid contained in the pump chamber out of the pump chamber.

20. The liquid pump apparatus of claim 19, wherein the relatively incompressible fluid comprises oil such that the fluid receiving volume comprises an oil receiving volume.

21. The liquid pump apparatus of claim 19, wherein the pump piston and drive piston are coaxially arranged relative to one another in the pump body.

22. The liquid pump apparatus of claim 19, wherein the releasing means comprises valve means for breaking the seal formed by the relatively incompressible fluid contained in the fluid receiving volume.

23. The liquid pump apparatus of claim 23, wherein the valve means comprises:

means for bleeding fluid between the fluid receiving volume and a supply of the fluid contained in the pump body; and

a valve portion for opening the bleeding means at the appropriate moment during movement of the piston assembly in the first direction thereof to allow a fluid bleed between the fluid supply and the fluid receiving volume to break the seal and release the pump piston from the drive piston.

24. The liquid pump apparatus of claim 23, wherein the valve portion is located in a bore in the pump body in which bore the drive piston is reciprocally contained.

25. A liquid pump apparatus for pumping a liquid at an increased pressure, wherein the apparatus is driven by a motive means that provides a source of power for the liquid pumping action, which comprises:

(a) a pump body having a pump chamber which is suited to be filled with the liquid that is to be pumped, the pump chamber having inlet means for admitting the liquid to the pump chamber and outlet means for allowing the liquid to exit from the pump chamber;

(b) a movable pump means operatively connected to the pump chamber for expanding and contracting the volume of the pump chamber as the pump means is moved;

(c) valve means associated with the inlet means and the outlet means for allowing the liquid to flow into the pump chamber through the inlet means when the pump means is moved in a direction in which the pump chamber is expanded and for allowing the liquid to be pumped out of the pump chamber through the outlet means when the pump means is moved in a direction in which the pump chamber is contracted;

(d) a drive means operatively connected to the motive means for operation over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber, wherein the drive means is separate from the pump means such that the pump means can move independently from the drive means over at least a portion of the movement of the pump means;

(e) means for operatively transmitting the movement of the drive means to the pump means during a portion of each pump cycle such that the transmitted motion moves the pump means at a first speed in the direction in which the pump chamber volume is expanded to fill the pump chamber with liquid; and

(f) means for uncoupling the motion transmitting means between the pump means and the drive means after the pump chamber volume has been expanded and filled with liquid and for then accelerating the pump means to a second speed which is faster than the first speed in a direction in which the pump chamber volume is contracted to pump the liquid out of the pump chamber at the increased pressure.

26. The liquid pump apparatus of claim 25, wherein the uncoupling and accelerating means comprises:

(a) means operatively connected to the pump means for storing energy and for supplying such energy against the pump means at a location which is suitable to drive the pump means in the direction in which the pump chamber volume is contracted; and

(b) control means for periodically allowing at least some of the energy stored in the energy storing means to be applied to the pump means.

27. The liquid pump apparatus of claim 26, further including means for periodically replenishing the energy stored in the energy storing means during the reciprocal motion of the pump means.

28. The liquid pump apparatus of claim 25, wherein the pump means comprises a pump piston which is reciprocally contained in an elongated pump bore in the pump body, and wherein the drive means comprises a drive piston that is reciprocally contained in an elongated drive bore in the pump body.

29. The liquid pump apparatus of claim 28, wherein the motive means includes a rotary crankshaft to which the drive piston is attached by a crankarm such that rotary motion of the crankshaft is converted into reciprocal motion of the drive piston.

30. The liquid pump apparatus of claim 28, wherein the pump bore and the drive bore comprise a single, common drive/pump bore in the pump body such that the pump piston and the drive piston reciprocate along the same axis.

31. A method of turf cultivation, which comprises:

(a) providing an implement which can travel over a turf area;

(b) providing on the implement a plurality of nozzle jets pointed downwardly towards the turf;

(c) providing on the implement a liquid pumping apparatus of the type comprising a pump piston reciprocally received in a bore for movement back and forth in the bore between the ends thereof, wherein a pump chamber comprises the volume of the bore located between the pump piston and the first end of the bore, and wherein the pump chamber is provided with liquid inlet means for admitting liquid into the pump chamber when the pump piston is moved away from the first end of the bore to expand the volume of the pump chamber and to fill it with a charge of the liquid, and the pump chamber is further provided with liquid outlet means for allowing liquid contained in the pump chamber to be expelled from the pump chamber when the pump piston is moved back towards the first end of the bore to contract the volume of the pump chamber and thereby force the liquid out of the pump chamber;

(d) connecting the liquid outlet means of the pumping apparatus to the nozzle jets so that the nozzle jets are supplied with liquid from the pumping apparatus;

(e) reciprocating the pump piston back and forth in the pump over a plurality of pump cycles, wherein the reciprocating step for a single pump cycle comprises;

(i) moving the pump piston at a first speed when the pump piston is moved away from the first end of the bore in its volume expanding direction; and

(ii) moving the pump piston at a second speed which is substantially greater than the first speed when the pump piston is moved back towards the first end of the bore in its volume contracting direction, wherein the second speed is sufficiently high such that the liquid is pumped at sufficient pressure to allow the nozzle jets to form the liquid into liquid jets which can penetrate the surface of the turf and create holes in the turf extending below the surface of the turf to thereby condition the turf; and

(f) moving the implement over the ground while the pump piston is reciprocated over a plurality of pump cycles to cause an array of spaced holes to be created in the turf by the nozzle jets.

32. A method of pumping a liquid out of a pump chamber in a pump body, wherein the pump body includes a movable pump means the motion of which cyclically expands and contracts a fluid receiving volume of the pump chamber to first fill the pump chamber with liquid and then expel the liquid from the pump chamber at an increased pressure, which comprises:

(a) providing a drive means that furnishes power for the pump means;

(b) operating the drive means such that the pump means is cyclically operated over a plurality of pump cycles with each pump cycle comprising a single filling of the pump chamber with liquid and a subsequent expelling of the liquid from the pump chamber;

(c) providing a pump means which is separate from the drive means to be capable of motion independent of the drive means;

(d) operatively coupling the pump means to the drive means over a first portion of the pump cycle such that the motion of the drive means is transmitted to the pump means during said pump cycle portion for causing the pump means to move at a first speed in its volume expanding direction in the pump chamber to fill the pump chamber with the liquid to be pumped;

(e) uncoupling the pump means from the drive means over a later portion of the pump cycle occurring after the pump means has been moved by the drive means in its volume expanding direction and the pump chamber has filled with liquid; and

(f) accelerating the pump means in its volume contracting direction independently of the drive means to a second speed faster than that of the first speed to allow the pump means to quickly contract the volume of the pump chamber and pump the liquid therein out an increased pressure.

33. A method as recited in claim 32, wherein the accelerating step comprises:

(a) providing an energy storing means;

(b) using the movement of the pump means in its volume expanding direction when filling the pump chamber with liquid to increase the energy stored in the energy storing means; and

(c) directing the energy stored in the energy storing means against the pump means such that the stored energy biases the pump means in its volume contracting direction to pump the liquid out of the pump chamber, whereby at least some of the energy stored in the energy storing means is used to accelerate the pump means in its volume contracting direction when the pump means is uncoupled from the drive means.

34. A method as recited in claim 32, further comprising reciprocating the pump means relative to the pump body which reciprocating motion comprises the cyclic motion of the pump means.

35. A method of pumping a liquid out of a pump chamber in a pump body, wherein the pump body includes an elongated bore having opposed first and second ends and a pump piston reciprocally received in the bore for movement back and forth in the bore between the ends thereof, wherein the pump chamber comprises the volume of the bore located between the pump piston and the first end of the bore, and wherein the pump chamber is provided with liquid inlet means for admitting liquid into the pump chamber when the pump piston is moved away from the first end of the bore to expand the volume of the pump chamber and to fill it with a charge of the liquid, and the pump chamber is further provided with liquid outlet means for allowing liquid contained in the pump chamber to be expelled from the pump chamber when the pump piston is moved back towards the first end of the bore to contract the volume of the pump chamber and thereby force the liquid out of the pump chamber, which comprises:

(a) moving the pump piston at a first speed when the pump piston is moved away from the first end of the bore in its volume expanding direction; and

(b) moving the pump piston at a second speed which is substantially greater than the first speed when the pump piston is moved back towards the first end of the bore in its volume contracting direction.

36. A method as recited in claim 35, wherein the second speed is in the range of from approximately 8 to 40 times faster than the first speed.

37. A method as recited in claim 35, further including the steps of:

(a) providing an energy storing means;

(b) using the movement of the pump piston in its volume expanding direction to increase the energy stored in the energy storing means; and

(c) using the energy stored in the energy storing means to accelerate the pump piston to its second speed when the pump piston moves in its volume contracting direction.