ELEMENT FOR COMPRESSING A GAS AND METHOD FOR CONTROLLING SUCH ELEMENT

Abstract

An element for compressing a gas with a housing (2) which encloses a compression chamber (5) with an outlet port (7) connected to the outlet. A rotor (8) is mounted so that the compression chamber (5) is divided into working chambers. A passage (10) extends between the outlet and a working chamber in the compression chamber (5) which is not in adjacent contact with the outlet port (7). The passage has an overpressure valve (11) to open the passage when a pressure difference between the working chamber and the outlet (4) exceeds a preset value. A valve body (12) encloses a buffer space (13) with a variable volume that is in fluid connection with the outlet through a constriction (14), so the volume is reduced and gas from the buffer space (13) flows through the constriction (14) to the outlet upon opening the passage (10).

Claims

1. An element for compressing a gas, wherein the element (1) comprises a housing (2) with an inlet (3) for gas and an outlet (4) for compressed gas, wherein the housing (2) encloses a compression chamber (5), which compression chamber (5) is provided in the housing (2) with an inlet port (6) connected to the inlet (3) and an outlet port (7) connected to the outlet (4), wherein the compression chamber (5) has a rotor (8) rotatably mounted relative to the housing (2) in such a manner that the rotor (8) divides the compression chamber (5) into several working chambers which are arranged successively in a direction from the inlet port (6) to the outlet port (7) and which are mutually sealed or almost sealed, such that on rotation of the rotor (8) in the compression chamber (5) the working chambers are successively created at the inlet port (6), subsequently move in a direction from the inlet port (6) to the outlet port (7), are reduced in volume after termination of a fluid contact with the inlet port (6), and eventually get into adjacent contact with the outlet port (7), wherein the element (1) is provided with a first passage (10) configured to be able to put the outlet (4) in fluid connection with a first working chamber in the compression chamber (5), which first working chamber is in such a first position that it is not yet in adjacent contact with the outlet port (7), wherein the first passage (10) is provided with a first overpressure valve (11) configured to open the first passage (10) when a first pressure difference between a pressure in the first working chamber in said first position and a pressure at the outlet (4) exceeds a first preset value and to close it when this first pressure difference is lower than the first preset value, wherein the first overpressure valve (11) includes a valve body (12) that encloses an internal buffer space (13) with a variable volume that is in fluid connection with the outlet (4) through a constriction (14), configured so that, upon opening the first passage (10), this variable volume is reduced and gas is carried from the internal buffer space (13) through the constriction (14) to the outlet (4), and so that, upon closing the first passage (10), this variable volume increases, and gas is carried from the outlet (4) through the constriction (14) to the internal buffer space (13).

2. The element according to claim 1, wherein the element (1) is provided with at least one second passage configured to be able to put the outlet (4) in fluid connection with the first working chamber in said first position, wherein the second passage is provided with a second overpressure valve configured to open the second passage when the first pressure difference exceeds the first preset value and to close it when the first pressure difference is lower than the first preset value.

3. The element according to claim 1, wherein the element (1) is provided with at least one third passage (15) configured to be able to put the outlet (4) in fluid connection with a second working chamber in the compression chamber (5), which second working chamber is in such a second position that it is not yet in adjacent contact with the outlet port (7) and which second working chamber differs from the first working chamber, wherein the third passage (15) is provided with a third overpressure valve (16) configured to open the third passage (15) when a second pressure difference between a pressure in the second working chamber in said second position and a pressure at the outlet (4) exceeds a second preset value and to close it when this second pressure difference is lower than the second preset value.

4. The element according to claim 3, wherein the element (1) is provided with at least one fourth passage configured to be able to put the outlet (4) into fluid connection with the second working chamber in said second position, wherein the fourth passage is provided with a fourth overpressure valve configured to open the fourth passage when a second pressure difference exceeds a second preset value and to close it when the second pressure difference is lower than the second preset value.

5. The element according to claim 3, wherein the first pressure difference and the second pressure difference are equal or almost equal.

6. The element according to claim 1, wherein the element (1) is a vacuum pump element.

7. The element according to claim 1, wherein the element (1) is a screw element.

8. The element according to claim 1, wherein the element (1) is a liquid-injected element.

9. The elements according to claim 1, wherein the first overpressure valve (11) is a spring-loaded valve.

10. The element according to claim 1, wherein the first passage (10) is provided with a valve seat (18), wherein the first overpressure valve (11) comprises a valve base (19) configured to be mounted in the housing (2), and wherein the first overpressure valve (11) comprises a part (20) that is movable relative to the valve base (19) and that is configured to make contact with the valve seat (18) and as such to close the first passage (10).

11. The element according to claim 10, wherein the valve base (19) is configured to be removably mounted in the housing (2).

12. The element according to claim 10, wherein the valve seat (18) and/or the movable part (20) are provided with an O-ring (21) for sealing the first passage (10).

13. The element according to claim 10, wherein the valve seat (18) and/or the movable part (20) are provided with an embedded piece of elastic material for sealing the first passage (10).

14. The element according to claim 13, wherein the elastic material is a vulcanized rubber.

15. The element according to claim 10, wherein the constriction (14) is provided in the valve base (19).

16. The element according to claim 1, wherein the constriction (14) has a smallest diameter which is smaller, in a direction perpendicular to a direction in which the first overpressure valve opens or closes, than a largest dimension of the internal buffer space (13).

17. The element according to claim 16, wherein a maximum ratio between said smallest diameter of the constriction (14) and said largest dimension of the internal buffer space (13) does not exceed 10%.

18. The element according to claim 16, wherein a minimum ratio between said smallest diameter of the constriction (14) and said largest dimension of said internal buffer space (13) is not lower than 4%.

19. An overpressure valve for use in an element according to claim 1.

20. A device for compressing a gas provided with an element according to claim 1.

21. A method for controlling an element for compressing a gas, wherein the element (1) comprises a housing (2) with an inlet (3) for gas and an outlet (4) for compressed gas, wherein the housing (2) encloses a compression chamber (5), which compression chamber (5) is provided in the housing (2) with an inlet port (6) connected to the inlet (3) and an outlet port (7) connected to the outlet (4), wherein the compression chamber (5) is divided by means of a rotor (8) into several, in a direction from the inlet port (6) to the outlet port (7), successive and mutually sealed or almost sealed working chambers, wherein on rotation of the rotor (8) in the compression chamber (5) the working chambers are successively created at the inlet port (6), subsequently move in a direction from the inlet port (6) to the outlet port (7), are reduced in volume after termination of a fluid contact with the inlet port (6), and eventually get into adjacent contact with the outlet port (7), wherein the element (1) is provided with a first passage (10) configured to be able to put the outlet (4) in fluid connection with the first working chamber in the compression chamber (5), which first working chamber is in a first position at which it is not yet in adjacent contact with the outlet port (7), wherein the first passage (10) is opened by means of a first overpressure valve (11) in the first passage (10) when a first pressure difference between a pressure in the first working chamber in said first position and a pressure at the outlet (4) exceeds a first preset value and is closed when the first pressure difference is lower than the first preset value, wherein upon opening the first passage (10), a variable volume of an internal buffer space (13) enclosed by a valve body (12) of the first overpressure valve (11) is reduced, and gas is carried from this internal buffer space (13) through a constriction (14) to the outlet (4), and upon closing the first passage (10), the variable volume increases, and gas is carried from the outlet (4) through the constriction (14) to the internal buffer space (13).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0106] To better demonstrate the features of the invention, the following describes, as an example without any restrictive character, a preferred embodiment of an element according to the invention, with reference to the accompanying drawings, wherein:

[0107] FIG. 1 shows, in perspective, an element according to the invention;

[0108] FIG. 2 shows a cross-section according to line II-II in FIG. 1;

[0109] FIG. 3 shows a part indicated as F3 in FIG. 2 in more detail.

DETAILED DESCRIPTION

[0110] The terminology used is intended only to describe the preferred embodiment by way of example and must not be interpreted as limiting for the scope of protection as defined in the claims.

[0111] Expressing terms in the singular, preceded by a/an or the, does not exclude that these terms may be present in the plural in the invention, except where defined otherwise.

[0112] Although the terms first, second, third or fourth are used below to refer to various working chambers, positions, passages, overpressure valves or preset values, these working chambers, positions, passages, overpressure valves or preset values are not limited to these terms. At most, these terms have only been used to distinguish a type of working chamber, position, passage, overpressure valve or preset value. When terms such as first, second, third or fourth are used in the following, these terms do not imply any particular sequence or order. Consequently, a first working chamber, position, passage, overpressure valve or preset value could just as easily be designated as, for example, a second or third working chamber, position, passage, overpressure valve or preset value without in that case going beyond the scope of the example embodiments. It should also be mentioned that there may be more first, second, third or fourth working chambers, positions, passages, overpressure valves or preset values.

[0113] FIG. 1 shows an element 1 for compressing gas, which element 1 comprises a housing 2 with an inlet 3 for gas and an outlet 4 for compressed gas.

[0114] FIG. 2 shows a cross-section of the element 1 according to line II-II in FIG. 1.

[0115] This cross-section reveals that housing 2 encloses a compression chamber 5 which compression chamber 5 is provided with an inlet port 6 which is coupled in fluid connection to the inlet 3 and an outlet port 7 which is coupled in fluid connection to the outlet 4.

[0116] In compression chamber 5, a rotor 8 is rotatably mounted relative to the housing 2 in such a manner that the rotor 8 divides the compression chamber 5 into several working chambers which are arranged successively in a direction from the inlet port 6 to the outlet port 7 and which are almost mutually sealed.

[0117] In this case, rotor 8 is designed as a screw rotor. In other words, element 1 is a screw element.

[0118] In this case, but not necessary for the invention, rotor 8 is rotatably mounted to housing 2 by means of bearings 9.

[0119] On rotation of the rotor 8 in the compression chamber 5, the working chambers 8 are successively created at the inlet port 6, subsequently move in a direction from the inlet port 6 to the outlet port 7, are reduced in volume after termination of a fluid contact with the inlet port 6 and eventually get into adjacent contact with the outlet port 7.

[0120] The element 1 is provided with a first passage 10 configured to be able to put the outlet 4 in fluid connection with a first working chamber in the compression chamber 5, which first working chamber is in such a first position that it is not yet in adjacent contact with the outlet port 7.

[0121] The first passage 10 is provided with a first overpressure valve 11 configured to open the first passage 10 when a first pressure difference between a pressure in the first working chamber in said first position and a pressure at the outlet 4 exceeds a first preset value and to close it when this first pressure difference is lower than the first preset value.

[0122] The first overpressure valve 11 includes a valve body 12 that encloses an internal buffer space 13 with a variable volume that is in fluid connection with the outlet 4 through a constriction 14.

[0123] Upon opening the first passage 10, the variable volume of the internal buffer space 13 is reduced, and gas from the internal buffer space 13 is carried through the constriction 14 to the outlet 4.

[0124] Upon closing the first passage 10, the variable volume of the internal buffer space 13 increases, and gas from the outlet 4 is carried through the constriction 14 to the internal buffer space 13.

[0125] The element 1 may be provided with a second passage (not shown in FIG. 2) configured to be able to put outlet 4 in fluid connection with the first working chamber in the compression chamber 5 when this first working chamber is in said first position.

[0126] Similar to the first passage 10, the second passage could be provided with a second overpressure valve with which the second passage is opened when the first pressure difference exceeds the first preset value and is closed when this first pressure difference is below the first preset value.

[0127] In the framework of the invention, it is not excluded that the outlet 4 can be put in fluid connection through more than two passages having one or several overpressure valves with the first working chamber in said first position.

[0128] In this case, but not necessary for the invention in general, the element 1 is provided with a third passage 15 which is configured to be able to put outlet 4 in fluid connection with a second working chamber in the compression chamber 5, which second working chamber is in such a second position that it is not yet in adjacent contact with the outlet port 7 and which second working chamber differs from said first working chamber.

[0129] The third passage 15 is provided with a third overpressure valve 16 with which the third passage 15 is opened when a second pressure difference between a pressure in the second working chamber in said second position and the pressure at the outlet 4 exceeds a second preset value and is closed when this second pressure difference is below the second preset value.

[0130] The element 1 may be provided with a fourth passage (not shown in FIG. 2) configured to be able to put outlet 4 in fluid connection with the second working chamber in said second position.

[0131] Similar to the first passage 15, the fourth passage could be provided with a fourth overpressure valve with which the fourth passage is opened when the second pressure difference exceeds the second preset value and is closed when the second pressure difference is below the second preset value.

[0132] In the framework of the invention it is not excluded that the outlet 4 can be put into fluid connection through more than two passages having one or several overpressure valves with the second working chamber in said second position.

[0133] Neither is it excluded in the framework of the invention that the element comprises at least one more passage which is configured to be able to put outlet 4 in fluid connection with at least one working chamber in the compression chamber 5, wherein this at least one working chamber is in such a third position that it has not yet been in adjacent contact with the outlet port 7 and this at least one working chamber differs from said first and second working chambers.

[0134] In this case the first overpressure valve 11 and the third overpressure valve 16 are designed as a spring-loaded valve, wherein the first overpressure valve 11 and the third overpressure valve 16 are closed by means of a spring force of a spring 17 when respectively the first or second pressure difference between the pressure of the gas in respectively the first or second working chamber in respectively the first or second position and the pressure at the outlet 4 is below respectively the first or second preset values.

[0135] In the framework of the invention it is not excluded that one of said overpressure valves in one of said passages does not comprise a spring, but is at least partially composed of a springy or elastic material, in which said springy or elastic material can deliver sufficient spring force for closing this overpressure valve at a pressure difference between a pressure in a working chamber in the compression chamber with which the passage is in fluid contact and a pressure at the outlet that is below a preset value.

[0136] Neither is it excluded in the framework of the invention that one of said overpressure valves in the element is a different type of valve, such as for instance a weight-loaded valve.

[0137] In this case the first passage 10 and the third passage 15 are provided with a valve seat 18, wherein respectively the first overpressure valve 11 and the third overpressure valve 16 comprise a valve base 19 which is configured to be mounted in the housing 2.

[0138] The first overpressure valve 11 and the third overpressure valve 16 comprise a part 20 that is movable relative to the valve base 19 that is configured to make contact with the valve seat and as such to close the first passage 10 or the third passage 15, respectively.

[0139] Here the movable part 20 is provided with an O-ring 21 for sealing the first passage 10.

[0140] In the framework of the invention it is not excluded that the O-ring 21 is provided on the valve seat 18, or that both the movable part 20 and the valve seat 18 are provided with an O-ring, or that the movable part 20 and/or the valve seat 18 are provided with several O-rings.

[0141] Neither is it excluded in the framework of this invention that, as an alternative or addition to the above-described O-ring, the movable part 20 and/or the valve seat 18 are provided with an embedded piece of elastic material for sealing the first passage 10 or the third passage 15. Preferentially, this embedded piece of elastic material is made of vulcanized rubber.

[0142] In this case the constriction 14 is provided in the valve base 19.

[0143] In this case the constriction 14 is also provided as a whole in the valve base 19 rather than in the housing 2 of the element 1.

[0144] However, in the framework of the invention it is not excluded that the constriction is at least partly provided in the housing 2.

[0145] FIG. 3 shows in more detail the first overpressure valve 11 in a part that is identified in FIG. 2 as F3.

[0146] The current invention is by no means limited to the embodiment described as example and shown in the figures, but an element according to the invention can be implemented in all shapes and sizes without going beyond the scope of the invention as defined in the claims.