Reciprocating piston motor, motor-pump assembly and method for driving a pump

Abstract

A reciprocating piston motor, motor-pump assembly and method for driving a pump. The piston motor includes a pressure medium housing, comprising a first pressure medium chamber having a first pressure medium piston, a second pressure medium chamber having a second pressure medium piston, and a pressure medium control system. The pressure medium control system includes a pressure medium inlet and outlet that are operatively connected to the pressure medium housing. The pressure medium control system is configured to move the pressure medium pistons. A coupling system is provided that is configured to combine the driving forces generated by the first and second pressure medium pistons for driving a fluid pump.

Claims

1. A reciprocating piston motor, comprising: a pressure medium housing, comprising: a first pressure medium chamber having a first pressure medium piston; and a second pressure medium chamber having a second pressure medium piston; and a pressure medium control system, comprising: a pressure medium inlet and outlet that are operatively connected to the pressure medium housing, wherein the pressure medium control system is configured to move the pressure medium pistons; wherein a coupling system is provided that is configured to combine driving forces generated by the first and second pressure medium pistons for driving a fluid pump, the coupling system comprises a by-pass connecting the first and second pressure medium chambers; and wherein the by-pass comprises a first by-pass and a second by-pass connecting respective parts of the pressure medium chambers on respective sides of the pressure medium pistons.

2. The reciprocating piston motor according to claim 1, wherein the pressure medium control system comprises a central control valve configured for steering the piston motor in co-operation with the coupling system.

3. The reciprocating piston motor according to claim 2, wherein the central control valve is positioned between the first and second pressure medium chambers.

4. The reciprocating piston motor according to claim 3, wherein the central control valve comprises a first end and a second end that in use are actuated by one of the pistons in the first and/or second pressure medium chamber.

5. The reciprocating piston motor according to claim 2, wherein the central control valve comprises at least one spring element configured for moving and/or maintaining the central control valve in a desired position.

6. The reciprocating piston motor according to claim 2, wherein the central control valve is substantially provided in a middle section between the first and second pressure chambers.

7. The reciprocating piston motor according to claim 6, wherein the middle section further comprises a pressure medium supply valve and at least one pressure medium outlet valve for controlling movement of the pressure medium pistons.

8. The reciprocating piston motor according to claim 7, wherein the pressure medium supply valve and the at least one pressure medium outlet valve are controlled by the control valve and move between their respective states in a joint motion.

9. The reciprocating piston motor according to claim 7, further comprising a locking system for holding one or more of the valves.

10. The reciprocating piston motor according to claim 9, wherein the locking system comprises one or more rolling elements.

11. The reciprocating piston motor according to claim 2, wherein the control valve further comprises a seal assembly with a core ring having a contact surface at an angle in the range of 25-75°.

12. The reciprocating piston motor according to claim 1, further comprising one or more air relieve valves comprising a blocking element and a spring element that is configured for maintaining the blocking element in its seat, wherein the air relieve valve is configured to allow fast reciprocating motion.

13. The reciprocating piston motor according to claim 1, further comprising a handle bar.

14. A motor-pump assembly, comprising: a reciprocating piston motor according to claim 1; and a fluid system, comprising: a fluid chamber having a fluid inlet and a fluid outlet that are operatively connected to the fluid chamber; and a fluid system piston that is moveable in the fluid chamber and is driven by the first and second pressure medium piston.

15. A method for driving a pump, comprising: providing a reciprocating piston motor according to claim 1; supplying pressure medium; and operating the motor.

16. The reciprocating piston motor according to claim 8, further comprising a locking system for holding one or more of the valves, wherein the locking system comprises one or more rolling elements.

17. The motor-pump assembly according to claim 14, wherein the pressure medium control system comprises a central control valve configured for steering the piston motor in co-operation with the coupling system, wherein the control valve is provided in a middle section between the first and second pressure medium chambers, wherein the middle section further comprises a pressure medium supply valve and at least one pressure medium outlet valve for controlling movement of the pressure medium pistons, further comprising a locking system for holding one or more of the valves, wherein the locking system comprises one or more rolling elements.

18. The method according to claim 15, wherein the pressure medium control system comprises a central control valve configured for steering the piston motor in co-operation with the coupling system, wherein the control valve is provided in a middle section between the first and second pressure medium chambers, wherein the middle section further comprises a pressure medium supply valve and at least one pressure medium outlet valves for controlling movement of the pressure medium pistons, further comprising a locking system for holding one or more of the valves, wherein the locking system comprises one or more rolling elements.

19. A reciprocating piston motor, comprising: a pressure medium housing, comprising: a first pressure medium chamber having a first pressure medium piston; and a second pressure medium chamber having a second pressure medium piston; and a pressure medium control system, comprising: a pressure medium inlet and outlet that are operatively connected to the pressure medium housing, wherein the pressure medium control system is configured to move the pressure medium pistons; wherein a coupling system is provided that is configured to combine driving forces generated by the first and second pressure medium pistons for driving a fluid pump, the coupling system comprises a by-pass connecting the first and second pressure medium chambers, and wherein the pressure medium housing further comprises a handlebar.

20. A reciprocating piston motor, comprising: a pressure medium housing, comprising: a first pressure medium chamber having a first pressure medium piston; and a second pressure medium chamber having a second pressure medium piston; and a pressure medium control system, comprising: a pressure medium inlet and outlet that are operatively connected to the pressure medium housing, wherein the pressure medium control system is configured to move the pressure medium pistons; wherein a coupling system is provided that is configured to combine driving forces generated by the first and second pressure medium pistons for driving a fluid pump, the coupling system comprises a by-pass connecting the first and second pressure medium chambers; wherein the pressure medium control system comprises a central control valve configured for steering the piston motor in co-operation with the coupling system; and wherein the central control valve comprises at least one spring element configured for moving and/or maintaining the central control valve in a desired position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

(2) FIG. 1 shows an embodiment of the reciprocating piston motor according to the invention;

(3) FIG. 2 shows a detailed view of the motor-pump assembly of FIG. 1;

(4) FIG. 3 shows the operational scheme of the assembly of FIGS. 1 and 2;

(5) FIGS. 4A and B show the dual piston configuration of the pressure medium housing in the assembly of FIGS. 1-3;

(6) FIG. 5 shows the pressure medium control system in the middle section of the motor of FIGS. 1-4; and

(7) FIG. 6 shows a detail of FIG. 5.

DETAILED DESCRIPTION

(8) Motor-pump assembly 2 (FIG. 1) comprises reciprocating piston motor 4 and fluid pump system 6. Motor 4 comprises first chamber 8 and second chamber 10 (FIG. 2). In chambers 8, 10 there are provided moveable pistons 12, 14 respectively. Pistons 12, 14 are connected to shaft or rod 16. Chambers 8, 10 comprise different parts 8a, 8b, 10a, 10b on respective sides of pistons 12, 14. Chambers 8, 10 are separated by middle section 18 and are provided in pressure medium housing 20. Pressure medium housing 20 is provided with handlebar 22 and is further provided with air exhaust 24, air controls 26 and compressed air inlet 28. Fluid system 6 comprises fluid inlet 30 and high pressure fluid outlet 32. Fluid system 6 further comprises fluid system housing 34 that is provided with fluid chamber 36 and fluid piston 38. In an illustrated embodiment piston 38 is connected via shaft or rod 40 to shaft or rod 16 of motor 4. Middle section 18 of housing 20 comprises control/pilot valve 42 and valve assembly 44.

(9) Valve assembly 44 (FIG. 3) comprises air exhaust valve 46, first air exhaust valve 48 and second air supply valve 50. Furthermore, motor 4 comprises first air relief valve 52 and second air relief valve 54. Furthermore, it will be understood by the skilled person that motor-pump assembly 2 may comprise a number of further pneumatic and/or hydraulic components in alternative configurations of the invention. In addition, the skilled person would understand that some other designs of the configuration could also be envisaged in accordance with the present invention.

(10) When air pressure is applied to motor 4, and air supply valve 46 is in the illustrated position, air will enter the left parts 8a, 10a of chambers 8, 10. This is achieved with the use of by-pass 56. In the illustrated embodiment the second exhaust valve 50 is closed. Also control valve 42 is closed as seen from the first parts 8a, 10a. Therefore, air pressure will be provided to parts 8a, 10a thereby moving pistons 12, 14 of motor 4 and pushing piston 38 of fluid system 6. No back pressure is built up in parts 8b, 10b on the opposite side of pistons 12, 14 as air is pushed out with the first air exhaust valve 48 being in the open position. Pistons 12, 14 move in a direction A (FIG. 4A). In the illustrated embodiment chamber parts 8b, 10b are connected with by-pass 58.

(11) At the end of the stroke the two joined pistons 12, 14 contact control valve 42 (FIG. 4B). At first end 60 and second end 62 of control valve 42 there are respectively provided first spring element 64 and second spring element 66. In the illustrated embodiment piston 12 contacts spring 64 and pushes first end 60 of control valve 42 further into middle section 18. This means that control valve 42 switches its operative position allowing air in part 10a to pressurize connection 68. Air supply valve 46 and second air exhaust valve 50 maintain their positions as they are “locked”. This lock will be explained later. First air exhaust valve 48 switches its position and closes exhaust passage 24a. The lock will break due to the control pressure build up, and air supply valve 46 and second air exhaust valve 50 are forced into their other alternative positions. In the illustrated embodiment this movement engages the “lock” between first air exhaust valve 48a and air supply valve 46. Then parts 8b, 10b are pressurized and parts 8a, 10a are connected to exhaust 24a such that pistons 12, 14 are moved in the opposite direction. At the end of the stroke, piston 14 will actuate control valve 42, more specifically end 62 and spring 66 thereof, such that connection 70 is actuated. Then second air exhaust valve 50 will switch and close exhaust 24b. Air pressure in connection 68 will build up and break the lock (as mentioned earlier) to simultaneously switch first air exhaust valve 48 and air supply valve 46. The lock between air supply valve 46 and second air exhaust 50 is set. Then the next cycle may start.

(12) In the illustrated embodiment when actuated control valve 42 closes passage of control air to chambers 8, 10 that was previously in contact with exhaust 24. The three main valves, i.e. first air exhaust valve 48, second air exhaust valve 50 and air supply valve 46 are pneumatically controlled on both sides. When pressurized on one side the air from the actuator on the other side needs to be able to escape. The compressed air on one side of the pistons 12, 14 is used to push out the air, through exhaust 24. On the other side back pressure may build up in the other parts. When actuating control valve 42 this back pressure will at first remain in connections 68, 70 that are linked to exhaust 24 and is now closed. The drive pressure is then applied to control valves 46, 48, 50. However, the valves are initially kept in their position due to the back pressure. Air exhaust valves 48, 50 are capable to bleed and prevent the building of this back pressure to assure that valves 46, 48, 50 will switch their position.

(13) Piston 38 in pump system 6 follows movement of pistons 12, 14 in motor 4. When pistons 12, 14 are pushed to the right hand side of the illustrated embodiment (direction A) fluid head 72 (FIG. 3) is pumped empty and its volume is pushed beyond piston 38 to chamber part 74. When pistons 12, 14 start moving in the opposite direction, fluid in chamber part 74 is pumped out through outlet 32 and new fluid enters fluid head 72 through inlet 30.

(14) Control valve 42 has two ends 60, 62 (FIGS. 4A, B) with valve core 76 extending between two ends 60, 62. In the illustrated embodiment (FIG. 4A) passage 78 is open and passage 80 is closed. Therefore, the pressure is acting on core 76 keeping it in its position. When piston 12 contacts control valve 42 (FIG. 4B) first spring element 64 is loaded and piston 12 continues to move towards middle section 18, while pushing valve core 76 forward. This opens passage 80 and closes passage 78. The pressure present in chamber part 10a is allowed into control system, more specifically in connection 68.

(15) In the illustrated embodiment valves 46, 48, 50 are provided in valve assembly 82 (FIG. 5, 6). In this illustrated embodiment valve assembly 82 (FIG. 5) is shown in a post-switch position. Control air travels to passage 84a, 84b, 84c, 84d and 84e. In this situation first air exhaust valve 48 is pushed outward into the position where valve 48 blocks passage between a pressure chamber part and exhaust 24a. In the illustrated embodiment a minimum pressure of 1 bar is required to unlock locked second air exhaust valve 50 with air supply valve 46. When the threshold pressure is reached both second air exhaust valve 50 and air supply valve 46 will switch position simultaneously. In the illustrated embodiment air supply valve 46 will move to the right diverting the air supply from the one chamber part to the other while second air exhaust valve 50 opens the passage between the respective chamber part and exhaust 24b. Due to the fact that first air exhaust valve 48 has moved to the left, and in the second stage air supply valve 46 has moved to the right, the lock between the first air exhaust valve 48 and air supply valve 46 engages, thereby locking them together for the next switching sequence when the pistons 12, 14 complete the full stroke in the other direction.

(16) Lock 86 (FIG. 6) comprises balls (or other suitable elements) 88 that are loaded by rings 90. The control pressure is supplied by the drive pressure from the respective chambers. Lock 86 uses conical surface 91 that cooperates with ball 88.

(17) In some situations, the air drive systems is slowed down by the counterforce from the fluid section. When the air drive is used to displace fluid the speed of the reciprocating motion is limited by the speed at which air is pushed out of the chamber part that is connected to exhaust 24. This may create a back pressure in the exhaust 24 and control system. This may result in a malfunction or disturbance. Therefore, air relieve valves 52, 54 are provided that are designed to keep the exhaust back pressure from a fast reciprocating motion below the threshold when a main valve assembly 82 malfunctions. This involves blocking element 92 by spring element 96 that pushes element 92 in its seat 96 (FIG. 5). It will be understood that this configuration can be designed in accordance with the required user specifications.

(18) Valve assembly 82 moves in opening 98 in middle section 18. A number of O-rings 100 limit valve motion at seal passages. This achieves a so-called seal-in-groove functionality.

(19) To reduce friction seal core 102 is provided with a contact surface that is put at an angle relative to the direction of movement of valve assembly 82. O-ring 104 cooperates with seal core 102. In the illustrated embodiment seal core 102 is a PTFE-ring, although other materials can also be envisaged in accordance with the present invention.

(20) The present invention is by no means limited to the above described and preferred embodiments thereof. The rights sought are defined in the following claims, within the scope of which many modifications can be envisaged.