PRESSURE EXCHANGER

Abstract

A pressure exchanger (1) including a housing (2), a drive shaft (3) and a cylinder drum (4) rotatably arranged in the housing (2) is described, the cylinder drum (4) including two front faces and at least one cylinder (5) between the front faces, wherein the housing (2) includes a port flange (7, 8) at each end of the cylinder drum (4) and at least at one end of the cylinder drum (4) a pressure shoe (18) is arranged between the cylinder drum (4) and the port flange of this end. Such a pressure exchanger should be operated in a cost-effective manner. To this end an adjustable stop arrangement (19) is arranged between the pressure shoe (18) and the cylinder drum (4).

Claims

1. A pressure exchanger comprising a housing, a drive shaft, and a cylinder drum rotatably arranged in the housing, the cylinder drum comprising two front faces and at least one cylinder between the front faces, wherein the housing comprises a port flange at each end of the cylinder drum and at least at one end of the cylinder drum a pressure shoe is arranged between the cylinder drum and the port flange of this end, wherein an adjustable stop arrangement is arranged between the pressure shoe and the cylinder drum.

2. The pressure exchanger according to claim 1, wherein the stop arrangement rotates together with the pressure shoe and the cylinder drum.

3. The pressure exchanger according to claim 1, wherein the stop arrangement is adjustable from the outside of the housing.

4. The pressure exchanger according to claim 1, wherein the stop arrangement comprises a holder which at least during operation of the pressure exchanger is held in a predefined axial position, wherein the holder comprises at least one stop element.

5. The pressure exchanger according to claim 4, wherein at least during operation of the pressure exchanger the holder rests against the cylinder drum.

6. The pressure exchanger according to claim 4, wherein during adjustment the stop element is moved axially with respect to the holder.

7. The pressure exchanger according to claim 6, wherein the stop element is in form of a pin having a constant cross section over an adjustment length.

8. The pressure exchanger according to claim 4, wherein the stop element is held with press fit in the holder.

9. The pressure exchanger according to claim 4, wherein the holder is in form of a plate arranged on the drive shaft and movable at least in axial direction together with the drive shaft.

10. The pressure exchanger according to claim 4, wherein an inner thread is provided at one end of the pressure exchanger, wherein the inner thread comprises an axis parallel to an axis of rotation of the drive shaft, wherein an adjustment bolt can be threaded in the inner thread to contact the drive shaft or the cylinder drum.

11. The pressure exchanger according to claim 10, wherein the drive shaft comprises a driven end and the inner thread is arranged opposite the driven end.

12. The pressure exchanger according to claim 10, wherein the inner thread is arranged at the end remote from the adjustable stop arrangement.

13. The pressure exchanger according to claim 4, wherein the cylinder drum comprises at least one blind hole in a front face and the at least one stop element protrudes into the blind hole.

14. The pressure exchanger according to claim 4, wherein the stop element protrudes out of the holder in a direction towards the pressure shoe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A preferred embodiment of the invention will now be described with reference to the drawing, in which:

[0025] FIG. 1 shows a schematic section in a view of a pressure exchanger,

[0026] FIG. 2 shows schematically a stop arrangement at the beginning of an adjustment,

[0027] FIG. 3 shows the stop arrangement at the end of the adjustment, and

[0028] FIG. 4 shows the stop arrangement before the start of the pressure exchanger.

DETAILED DESCRIPTION

[0029] In all Figures the same elements are denoted with the same reference numerals.

[0030] FIG. 1 schematically shows a pressure exchanger 1 comprising a housing 2, a drive shaft 3 and a cylinder drum 4 which is rotatably arranged in the housing 2. The cylinder drum 4 comprises a plurality of cylinders 5 which are evenly distributed in circumferential direction around the drive shaft 3. However, theoretically one cylinder 5 would be sufficient.

[0031] The cylinder drum is rotationally fixed to the drive shaft 3. The drive shaft 3 comprises a driven end 6.

[0032] The driven end 6 can be provided with a coupling to connect a drive motor or other driving means to rotate the drive shaft 3.

[0033] Port flanges 7, 8 are arranged at each end of the cylinder drum 4. The cylinder drum 4 rotates with respect to the port flanges 7, 8.

[0034] First port flange 7 comprises two kidney-shaped openings 9, 10 which are connected to ports 11, 12 in an end part 13 of the housing 2. The second port flange 8 comprises two kidney-shaped openings 14, 15 which are connected to port 16 (the other port is not shown) in a second end part 17 of the housing.

[0035] A pressure shoe 18 is arranged between the cylinder drum 4 and the second port flange 8. The pressure shoe 18 is sealed with respect to the cylinders 5 of the cylinder drum 4 (seals are not shown) and is slightly moveable with respect to the cylinder drum 4, so that during operation it can be held in contact with the second port flange 8.

[0036] During operation, i.e. when fluids in the pressure exchanger 1 already have an elevated pressure, these pressures produce forces on the pressure shoe 18, which are balanced such that the pressure shoe 18 is held with low friction against the second port flange 8 to secure a tightness in the contact area between the second port flange 8 and the pressure shoe 18, however, with a low friction between the pressure shoe 18 and the second port flange 8. The pressure shoe 18 rotates together with the cylinder drum 4.

[0037] However, when the pressure exchanger 1 is started the necessary pressures in the fluids are not available.

[0038] In order to achieve nevertheless the necessary tightness within the pressure exchanger 1, a stop arrangement 19 is provided limiting a movement of the pressure shoe 18 away from the second port flange 8. As will be explained later on, the stop arrangement 19 limits a movement of the pressure shoe 18 away from the second port flange 8 so that a gap between the pressure show 18 and the second port flange 8 does not exceed a predefined and allowable size.

[0039] The stop arrangement 19 will be explained in more detail with reference to FIGS. 2 to 4.

[0040] The stop arrangement 19 comprises a holder 20 in form of a disk or plate which is mounted on the drive shaft 3 and rests against the cylinder drum 4. The holder 20 holds a number of stop elements 21 (only one shown in FIGS. 2 to 4). The stop elements 21 are distributed in circumferential direction around the drive shaft 3. In a preferred embodiment there are twelve stop elements 21.

[0041] Before adjusting the stop arrangement 19, the stop element 21 protrudes out of the holder 20 at least in a direction towards the pressure shoe 18. However, it is preferred that the stop element 21 protrudes out of the holder 20 on both sides.

[0042] The cylinder drum 4 comprises a number of blind holes 22. These blind holes 22 accommodate an end of the stop element 21 protruding out of the holder 20 in a direction towards the cylinder drum 4. The blind holes 22 are a result of the fact that the cylinder drum 4 is of the same type as a cylinder drum which has been used together with a spring arrangement.

[0043] The stop elements 21 are in form of a pin having a constant cross section (at least over an adjustment length). The stop elements 21 are held in the holder 20 with press fit. When a force is exerted on the stop element 21 which overcomes the force produced by the press fit, the stop element 21 can be moved with respect to the holder 20. This movement is directed parallel to the axis of rotation of the drive shaft 3.

[0044] FIG. 1 shows means for producing such forces.

[0045] The first end part 13 is provided with an inner thread 23. The inner thread can be provided in a thread element 24 which can be fixed to the first end part 13 and can be removed from the first end part 13 after the adjustment. A bolt 25 can be threaded into the inner thread 23. The bolt 25 is threaded into the inner thread 23 until it contacts the drive shaft 3. Alternatively, it can contact directly the cylinder drum 4.

[0046] Thus, when the bolt 25 is rotated, it can move the drive shaft 3 in axial direction towards the second end part 17. When the drive shaft 3 is moved axially, the cylinder drum 4 is also moved axially and the holder 20 which contacts the cylinder drum 4 is also moved axially in a direction towards the second end part 17 and thus towards the pressure shoe 18.

[0047] Due to this movement of the cylinder drum 4 the stop element 21 comes in contact with the pressure shoe 18 (FIG. 2). Upon further movement of the cylinder drum 4 the stop element 21 is moved in relation to the holder 20, so that the end contacting the pressure shoe 18 will be shorter and the length of the end protruding into the blind hole 22 will be longer.

[0048] When the pitch of the thread 23 is known, it is possible to precisely adjust the axial position of the holder 20. When the thread 23, for example, has a pitch of 1.5 mm per revolution, rotating the bolt 25 by 24° will cause a movement of the cylinder drum 4 and consequently of the holder 20 by 0.1 mm.

[0049] Thus, it is possible to adjust the holder 20 and together with the holder the stop elements 21 so that (after removing the bolt 25) a gap 26 is formed between the stop elements 21 and the pressure shoe 18. This gap 26 can have, for example, a thickness of 0.1 to 0.8 mm, in particular 0.2, 0.3, or 0.4 mm.

[0050] The pressure shoe 18 is allowed to move away from the second port flange 8 by the same distance.

[0051] This means that without other forces a gap can form between the pressure shoe 18 and the second port flange 8 in the same magnitude as the gap 26.

[0052] Thus, when the pressure exchanger 8 is started, the pressure shoe 18 slides with low friction or almost no friction over the second port flange 8. Although a small volume of hydraulic fluid can escape through the gap between the pressure shoe 18 and the second port flange 8, this leakage is so small that enough pressure can build up so that this pressure can exert the necessary forces onto a pressure shoe 18 to press it with sufficient, but not too high forces against the second port flange 8.

[0053] In the above, only one pressure shoe 18 on the valve of the cylinder drum 4 facing the second end part 17 has been described. However, another pressure shoe 27 can be arranged between the other side of the cylinder drum 4 and the first port flange 7. In this case the two pressures shoes 18, 27 have to share the allowable movement which is defined by the gap 26.

[0054] Thus, during start too big leakage is avoided and too much friction is also avoided, so that the pressure exchanger 1 can be operated with a drive motor which is sufficient for normal operation but needs not to overcome large torques during start of the pressure exchanger 1.

[0055] While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.