Diaphragm pump

Abstract

The invention relates to a diaphragm pump for delivering and / or compressing a fluid, comprising: a first chamber component having a first surface, the first surface defining a substantially concave stop contour; a flexible diaphragm which, together with the first surface, defines a working chamber that is variable by means of a deflection of the diaphragm; a piston plate which is located on a first side of the diaphragm remote from the working chamber, is connected to the diaphragm, and at least portions of which piston plate have, on a pressure side of the piston plate close to the diaphragm, a substantially convex piston contour which is substantially complementary to the stop contour; and a lifting drive which is designed to deflect the diaphragm via the piston plate and to apply an oscillating movement to the diaphragm.

Description

[0001] R. 412016

[0002] - 1 -

[0003] Description

[0004] title

[0005] Diaphragm pump

[0006] The invention relates to a diaphragm pump and a compressor. In particular, the invention relates to a diaphragm pump and a compressor for use in a cooling and / or refrigerant circuit, for example in a refrigerator or in a heat pump.

[0007] State of the art

[0008] In the prior art, the diaphragm of a diaphragm pump is driven by plungers or by gaseous or liquid working fluids. If plungers are used, they can be screwed tightly to the diaphragm or fixed by being molded into the diaphragm material.

[0009] Common diaphragm pumps have limitations regarding their pumping capacity and durability, which is why they are rarely, if ever, used in certain applications. For example, piston pumps are predominantly used in refrigerant compressors, such as those found in refrigerators or heat pumps. Disadvantages of piston pumps include their relatively high noise level during operation, energy losses due to friction of the moving parts, and the need for lubrication.

[0010] It is an object of the invention to provide an alternative or improved diaphragm pump and an alternative or improved compressor for use in a cooling and / or refrigerant circuit.

[0011] Disclosure of the invention R. 412016

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[0013] The object of the invention is achieved by means of a diaphragm pump according to claim 1, and by means of a compressor according to claim 17. Advantageous further developments, additional features and / or advantages of the invention will become apparent from the dependent claims and the following description.

[0014] According to a first aspect, the following is disclosed:

[0015] A diaphragm pump for conveying and / or compressing a fluid, comprising: a first chamber component comprising a first surface, wherein the first surface defines a substantially concave stop contour; a flexible diaphragm which, together with the first surface, defines a working space which varies with a deflection of the diaphragm; a piston plate arranged on a first side of the diaphragm facing away from the working space and connected to the diaphragm, which has, at least partially, a piston contour on a pressure side of the piston plate facing the diaphragm that is substantially complementary to the stop contour and substantially convex; a stroke drive which is configured to deflect the diaphragm over the piston plate and to subject it to an oscillating motion.

[0016] The membrane can seal off the working space fluid-tight along a boundary zone of the membrane.

[0017] The first chamber component can be part of a pump housing, wherein the diaphragm has a rim bead along the edge zone which is clamped in a corresponding annular gap of the pump housing.

[0018] The first chamber component can separate a fluid reservoir formed in the pump housing from the working chamber.

[0019] The fluid reservoir and the working chamber can be fluidically connected via an inlet opening in the first chamber component. R. 412016

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[0021] The diaphragm pump may include an inlet valve which is arranged at or in the inlet opening and is designed to prevent a flow of fluid from the working chamber into the fluid reservoir.

[0022] The diaphragm pump can include a fluid conductor that is fluidically connected to the working chamber via an outlet opening in the first chamber component.

[0023] The diaphragm pump may include an outlet valve, which is located at the outlet opening and is designed to prevent fluid from flowing out of the fluid conductor into the working chamber.

[0024] The membrane and the stamping plate can be connected to each other in a central section of the membrane via an anchor component.

[0025] The membrane can have a recess in the central section with a central bead extending around the recess and projecting into the working space; the piston plate can have a central channel extending into the piston plate from the pressure side; the anchor component can have a substantially disc-shaped flange section arranged in the working space and cooperating with the central bead, as well as a pin-shaped longitudinal section cooperating with the central channel, wherein the longitudinal section extends from the flange section through the recess and is held in the central channel.

[0026] The flange section can have a circular ring section surrounding an edge of the flange section and projecting from it towards the membrane, complementary to the central bead, within which the central bead is held and clamped between the flange section and the pressure side of the piston plate.

[0027] The longitudinal section can be held in the central channel by a thread and / or by a press fit. R. 412016

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[0029] The first surface may have a recess in a central section that is complementary to the flange section of the anchor component, for receiving the flange section during the oscillating movement of the punch plate.

[0030] The inlet opening and the outlet opening can be located in the area of ​​the recess in the first chamber component.

[0031] The punch plate can be preferably integrally connected to a piston rod extending substantially perpendicularly from the punch plate, wherein the piston rod is connected to the stroke drive at an end remote from the punch plate.

[0032] The first chamber component can form a lid section of a cylinder in which the piston plate is mounted to oscillate, with the diaphragm dividing the interior of the cylinder into the working chamber and a piston chamber in a fluid-tight manner.

[0033] According to another aspect, the following is disclosed:

[0034] A compressor for a refrigerant circuit, preferably for a refrigerant circuit of a refrigerator, comprising a diaphragm pump as defined above.

[0035] Brief description of the characters

[0036] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying schematic drawing, which is not to scale. The figures (Fig.) in the drawing are merely examples and show:

[0037] Fig. 1 schematically shows an embodiment of a diaphragm pump.

[0038] The structure and operation of a diaphragm pump are described schematically below with reference to Figure 1. R. 412016

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[0040] Figure 1 schematically shows components of a pump assembly of a compressor 300 for compressing gaseous and / or liquid media, hereinafter collectively referred to as fluids. While the application of a diaphragm pump 10 as a component of a compressor is described here, it should be noted that the diaphragm pump 10 can also be used in pumping devices in which fluid is merely conveyed but not compressed.

[0041] A working chamber 50, whose volume varies cyclically, is defined at least partially by a first surface 23 of a first chamber component 20 and by a flexible membrane 40. In the illustrated embodiment, the first chamber component 20 is part of a pump housing 24 and delimits the working chamber 50 in a first direction, which can be referred to as the z-direction with respect to the coordinate system shown in the figure. The membrane 40 seals the working chamber 50 fluid-tight along a boundary zone 44 of the membrane 40. For this purpose, in the illustrated embodiment, it has a rim 46 along the boundary zone 44, which is clamped in a corresponding circumferential annular gap 25 of the pump housing 24.

[0042] The pump housing 24 incorporates a fluid reservoir 200, which is separated from the working chamber 50 by the first chamber component 20 and contains the fluid to be pumped or compressed. In an application where the compressor is part of a refrigerant circuit, the fluid in the fluid reservoir 200, which is fed by a first heat exchanger, is at least partially in liquid form.

[0043] The membrane 40 is deflectable perpendicular to its principal plane of extension, which in the figure runs essentially parallel to the x-axis, in a lifting motion corresponding to the z-direction in the figure. With the deflection of the membrane 40, the volume of the working space 50 changes. In a position where the membrane 40 is deflected almost to the first surface 23 and the volume of the working space 50 essentially disappears, the top dead center of the lifting motion is reached. If the R. 412016

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[0045] When the membrane 40 reaches a position in which both its distance to the first surface 23 and the volume of the working space 50 are at their maximum, a bottom dead center of the stroke movement is reached. During the stroke movement, the membrane 40 oscillates cyclically between the first dead center and the second dead center along the stroke direction.

[0046] The lifting motion is generated by a lifting drive (not shown in the figure), which is connected to the diaphragm 40 via a piston plate 60 arranged on a first side 42 of the diaphragm 40 facing away from the working chamber 50 and connected to the diaphragm 40. The piston plate 60, in turn, is connected to a piston rod 71 projecting substantially perpendicularly from the piston plate 60, the piston rod 71 being connected to the lifting drive at an end remote from the piston plate 60. The lifting drive itself can be designed, for example, as an electric motor with a crank drive or as an electric linear motor.

[0047] In the embodiment shown in Figure 1, the first chamber component 20 forms a cover section of a cylinder 73 in which the piston plate 60 is mounted or guided for oscillation. The diaphragm 40 divides the interior of the cylinder 73 into a fluid-tight working chamber 50 and a piston chamber 52. This separates the fluid from any medium located in the piston chamber, which is advantageous in certain applications, for example, when the fluid to be compressed should not be contaminated as much as possible or when the fluid to be compressed has negative effects, such as corrosive effects, on components located in the piston chamber 52.

[0048] During an initial stroke, in which the diaphragm 40 is moved by the piston rod 71 from top dead center to bottom dead center, i.e., in a direction opposite to the positive z-axis in Figure 1, the volume of the working chamber 50 increases, resulting in a negative pressure in the working chamber 50. As a consequence of this negative pressure, fluid is drawn from the fluid reservoir 200 into the working chamber 50 through an inlet opening 21, which is located in the first chamber component 20 and fluidically connects the fluid reservoir 200 to the working chamber 50. R. 412016

[0049] - 7 - An inlet valve 22 is arranged in the inlet opening 21, which is designed as a check valve such that it allows fluid from the fluid reservoir 200 to enter the working chamber 50, but prevents backflow of fluid from the working chamber 50 into the fluid reservoir 200. In embodiments of the diaphragm pump 10, the inlet valve 22 is designed as an elastic flap arranged on an inner surface of the first surface 23, which can be pressed into the working chamber 50 by fluid flowing from the fluid reservoir 200 into the working chamber 50, and which, when overpressure develops in the working chamber 50, moves in front of the inlet opening 21 and thus closes it. In alternative embodiments, the inlet valve 22 is designed in a manner known per se as a spring-loaded ball which is pressed against a spring force from a corresponding sealing bearing by the fluid flowing from the fluid reservoir 200 into the working chamber 50.

[0050] The portion of the stroke after passing bottom dead center, when the diaphragm 40 is moved by the piston rod 71 towards the first surface 23, is called the compression stroke. During the compression stroke, the volume of the working chamber 50 is reduced, and consequently, an overpressure builds up in the working chamber 50. As a result of this overpressure, an outlet valve 27, located in an outlet opening 26 of the first chamber component 20, opens a flow path through a fluid line 110, which is fluidically connected to the outlet opening 26. In an application where the compressor is part of a refrigerant circuit, the fluid is supplied to a second heat exchanger via the fluid line 110. The outlet valve 27 is designed as a check valve such that it allows fluid to flow from the working chamber 50 into the fluid line 110, but prevents backflow of fluid from the fluid line 110 into the working chamber 50.The exhaust valve 27 can be constructed in various ways, as already explained in relation to the inlet valve 22, for example as an elastic flap or as a spring-loaded ball.

[0051] As can be seen in Figure 1, the first surface 23 defines a substantially concave stop contour 30 facing the working area 50. This feature can also be described as the first surface 23 being curved, at least section by section, such that in the case of a R. 412016

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[0053] In the neutral position, the height of the working space 50, measured along or parallel to the stroke direction of the membrane 40, increases from an edge 40 of the membrane towards its center. Referring to Figure 1, it can also be said that the stop contour 30 is curved in such a way that it forms a shell open towards the working space 50. As will be described in more detail later, the first surface 23 has a recess 32 in a central section 31, which will be discussed in more detail later. In the areas of the first surface 23 that are located outside the recess 32, the first contour 23 essentially has a profile that can be approximated by the mathematical function of a negative hyperbolic cosine (in mathematical notation and with reference to the coordinate system shown in Figure 1: f(x) = - cosh(x)).In the embodiment shown in Figure 1, this function is, in a sense, reversed, which is why the minus sign is used before the hyperbolic cosine. In embodiments in which the first surface 23 has no depression in the central region 31, the stop contour runs continuously and concavely curved over the central region 31.

[0054] One pressure side 62 of the piston plate, facing the diaphragm 40, has, at least in sections, a piston contour 63 that is essentially complementary to the stop contour 30 and essentially convex. This can be easily seen in Figure 1, where, outside the central area corresponding to the recess 32, the piston contour 63 has a course that is essentially parallel to the stop contour. This means that at the top dead center of the stroke, the diaphragm 40 is clamped or fixed between the stop contour 30 and the piston contour 63, which is complementary to it, in a substantially continuous, sandwich-like manner. In other words, the diaphragm 40 closes the compression stroke in such a way that no protrusions or bulges of the diaphragm 40 can occur, but rather the diaphragm lies smoothly against the first surface 23.

[0055] This ensures maximum efficiency of the lifting motion, as the volume of the working space is reduced to zero or close to zero, thus eliminating all R. 412016

[0056] - 9 - fluid located in the working chamber 50 is displaced from the working chamber 50 into the fluid conductor 110. Furthermore, this ensures that the diaphragm 40 is progressively supported by the piston contour 63 during the compression stroke, and in particular, that bulges and local load introductions associated with inflection points in the deformation pattern of the diaphragm 40 are avoided. As can be seen in Figure 1, during the introduction stroke, the diaphragm 40 can roll from the edge zone 44 along the piston contour of the piston component 60, which results in a smooth transition of the local curvature of the diaphragm 40 into the position it has when reaching top dead center. In this way, the mechanical stress on the diaphragm 40 can be reduced and its service life increased, or the compression pressure achievable by the diaphragm 40 and the frequency of the compressor can be increased.This aspect is particularly important for fluids at low temperatures, where the plastic materials typically used for the diaphragm 40 become progressively brittle, and the support of the diaphragm 40 by the interaction of the piston contour 63 with the stop contour 23 is extremely advantageous. It is also advantageous that the force transmission from the piston rod 71 to the diaphragm 40 is distributed evenly and uniformly over a surface, so that no negative effects from local, concentrated load application occur.

[0057] According to another aspect, the concave stop contour 63 and the complementary, convex piston contour 63 interact in such a way that the volume of the working chamber 50 is reduced more rapidly during the compression stroke in a peripheral region, which in Figure 1 is oriented towards an edge zone 44 of the diaphragm 40, compared to the central region. This means that the pressure ultimately transmitted by the piston rod 71 to the diaphragm 40 and the fluid is concentrated at an early stage in the center of the working chamber 50. In this embodiment, the outlet opening 26 is located precisely in this central region of the working chamber 50, which means that the fluid flow is advantageously concentrated towards the outlet opening 26. R. 412016

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[0059] The membrane 40 and the piston plate 60 are connected to each other in a central section 41 of the membrane 40 via an anchor component 70. For this purpose, the membrane 40 has a recess 43 in the central section 41 with a central bead 45 that surrounds the recess 43 and projects into the working chamber 50. The anchor component 70 has a substantially disc-shaped flange section 74 arranged in the working chamber 50 and interacting with the central bead 45, clamping the central bead 45 between the anchor component 70 and the piston component 60. In the illustrated embodiment, the flange section 74 has an annular section 75 that surrounds an edge of the flange section 74 and projects from it in the direction of the membrane 40, i.e., in the negative z-direction in the figure, and is complementary to the central bead 45.The circular ring section 75 encompasses and holds the central bead 45 and clamps it between the flange section 74 and the pressure side 62 of the punch plate 60.

[0060] The anchor component 70 has a pin-shaped longitudinal section 75 that projects essentially perpendicularly from the flange section 74 towards the piston plate 60. The longitudinal section 75 extends from the flange section 74 through the recess 43 in the diaphragm 40 and is held in the piston plate 60 in a central channel 61, which is arranged in the piston plate 60 from the pressure side 62. The longitudinal section 75 can be held in the central channel 61 by a thread and / or by a press fit.

[0061] As mentioned above, in the illustrated embodiment, the first surface 23 has a recess 32 in its central section 31 that is complementary to the flange section 74 of the anchor component 70. This recess 32 is designed to receive the flange section 74 of the anchor component 70 when the flange section 74 reaches top dead center during the oscillating movement of the piston plate 60. As can be seen in Figure 1, the flange section is essentially straight and perpendicular to the stroke direction, and the recess 32 is accordingly also flat and perpendicular to the stroke direction. The inlet opening 21 and the outlet opening 26 are located in the area of ​​the recess 32 in the first surface 23. R. 412016

[0062] - 11 - and thus arranged in the first chamber component 20, as already mentioned above.

[0063] When used in a compressor for refrigerant circuits, the diaphragm pump 10 described above is capable of providing previously unattainable refrigerant pressures and making the advantageous concept of a diaphragm pump, which can be operated essentially without lubrication, applicable to such applications, for example in refrigerators. The novel method of force transmission between the piston plate 60 and the diaphragm 40, as well as the corresponding shapes of the stop contour 30 and the piston contour 63, result not only in high pressures but also in a long service life for the diaphragm 40.

[0064] The invention is not limited to the described and illustrated embodiments. Rather, it also encompasses all further developments by skilled craftsmen within the scope of the invention defined by the claims. In addition to the described and illustrated embodiments, further embodiments are conceivable, which may include further modifications and combinations of features.

Claims

R. 412016 - 12 - Claims 1. Diaphragm pump (10) for conveying and / or compressing a fluid, comprising: a first chamber component (20) comprising a first surface (23), wherein the first surface (23) defines a substantially concave stop contour (30); a flexible diaphragm (40) which, together with the first surface (23), defines a working space (50) which varies with a deflection of the diaphragm (40); a piston plate (60) arranged on a first side (42) of the diaphragm (40) facing away from the working space (50) and connected to the diaphragm (40), which, on a pressure side (62) of the piston plate (60) facing the diaphragm (40), has at least partially a piston contour (63) that is substantially complementary to the stop contour (30) and substantially convex; a lifting drive (100) which is designed to deflect the diaphragm (40) over the piston plate (60) and to subject it to an oscillating movement.

2. Diaphragm pump (10) according to claim 1, wherein the diaphragm (40) seals the working chamber (50) fluid-tight along a boundary zone (44) of the diaphragm (40).

3. Diaphragm pump (10) according to claim 2, wherein the first chamber component (20) is part of a pump housing (24) and wherein the diaphragm (40) has a rim bead (46) along the edge zone (44) which is clamped in a corresponding annular gap (25) of the pump housing (24).

4. Diaphragm pump (10) according to one of the preceding claims, wherein the first chamber component (20) separates a fluid reservoir (200) formed in the pump housing (24) from the working chamber (50). R. 412016 - 13 - 5. Diaphragm pump (10) according to claim 4, wherein the fluid reservoir (200) and the working chamber (50) are fluidically connected via an inlet opening (21) in the first chamber component (20).

6. Diaphragm pump (10) according to claim 5, comprising an inlet valve (22) which is arranged on or in the inlet opening (21) and is configured to prevent a flow of fluid from the working chamber (50) into the fluid reservoir (200).

7. Diaphragm pump (10) according to one of claims 1 to 6, comprising a fluid conductor (110) which is fluidically connected to the working chamber (50) via an outlet opening (26) in the first chamber component (20).

8. Diaphragm pump (10) according to claim 7, comprising an outlet valve (27) which is arranged at the outlet opening (26) and is configured to prevent a flow of fluid from the fluid conductor (110) into the working chamber (50).

9. Diaphragm pump (10) according to one of claims 1 to 8, wherein the diaphragm (40) and the piston plate (60) are connected to each other in a central section (41) of the diaphragm (40) via an anchor component (70).

10. Diaphragm pump (10) according to claim 9, wherein: the diaphragm (40) has a recess (43) in the central section (41) with a central bead (45) circumferential around the recess (43) and projecting into the working chamber (50); the piston plate (60) has a central channel (61) extending from the pressure side (62) into the piston plate (60); the armature component (70) has a substantially disk-shaped flange section (74) arranged in the working chamber (50) and cooperating with the central bead (45), and a pin-shaped longitudinal section (75) cooperating with the central channel (61), wherein the longitudinal section (75) extends from the flange section (74) through the recess (43) and is held in the central channel (61).

11. Diaphragm pump (10) according to claim 10, wherein the flange section (74) has a circumferential ring around an edge of the flange section (74) and is R. 412016 - 14 - this circular ring section (75) projecting towards the membrane (40) and complementary to the central bead (45), within which the central bead (45) is held and clamped between the flange section (74) and the pressure side (62) of the punch plate (60).

12. Diaphragm pump (10) according to claim 11, wherein the longitudinal section (75) is held in the central channel (61) by a thread and / or by a press fit.

13. Diaphragm pump (10) according to one of the preceding claims, wherein the first surface (23) in a central section (31) thereof has a recess (32) complementary to the flange section (74) of the armature component (70) for receiving the flange section (74) during the oscillating movement of the piston plate (60).

14. Diaphragm pump (10) according to claim 13, wherein the inlet opening (21) and the outlet opening (26) are arranged in the area of ​​the recess (32) in the first chamber component (20).

15. Diaphragm pump (10) according to one of the preceding claims, wherein the piston plate (60) is preferably integrally connected to a piston rod (71) extending substantially perpendicularly from the piston plate (60), wherein the piston rod (71) is connected to the stroke drive (100) at an end remote from the piston plate (60).

16. Diaphragm pump according to one of the preceding claims, wherein the first chamber component (20) forms a cover section of a cylinder (73) in which the piston plate (60) is mounted to be oscillating, and wherein the diaphragm (40) divides an interior of the cylinder (73) into the working chamber (50) and a piston chamber (52) in a fluid-tight manner.

17. Compressor for a refrigerant circuit, preferably for a refrigerant circuit of a refrigerator, comprising a diaphragm pump (10) according to one of claims 1 to 16.

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