Reciprocating piston compressor
The pistonless oil pump in the reciprocating compressor addresses the challenges of service life, maintenance, and efficiency by using a deformable area and check valves to efficiently pump oil to the piston-cylinder gap, enhancing lubrication and reducing component size and costs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-11-10
- Publication Date
- 2026-06-18
AI Technical Summary
Existing reciprocating compressors face challenges in achieving improved service life, reduced maintenance requirements, and high efficiency while maintaining wear resistance, particularly in the lubrication and sealing of the piston and cylinder gap.
A reciprocating compressor design featuring a pistonless oil pump with a hollow body, deformable area, and check valves to cyclically change volume, allowing oil to be pumped from a reservoir to the gap between the cylinder and piston without an additional piston, using a deformable section that can be made of elastomer and controlled by the piston's movement.
This design enhances oil film formation, reduces component size, lowers manufacturing and maintenance costs, and improves efficiency by optimizing oil transfer and preventing backflow, resulting in a more compact and efficient compressor.
Smart Images
Figure EP2025082414_18062026_PF_FP_ABST
Abstract
Description
[0001] R. 412009
[0002] - 1 -
[0003] Description
[0004] title
[0005] reciprocating compressor
[0006] The invention relates to a reciprocating compressor, in particular for cooling devices.
[0007] State of the art
[0008] Reciprocating compressors are known from the state of the art.
[0009] For the lubrication and sealing of reciprocating compressors, an oil film is necessary in the gap between a piston and a cylinder. Oil pumps are used to create an oil circuit for a reciprocating compressor. The oil pumps circulate oil using a piston located inside the pump.
[0010] A reciprocating pump is known from US 8,070,460 B2.
[0011] Disclosure of the invention
[0012] The object underlying the invention can be seen as providing an improved reciprocating compressor. In particular, the reciprocating compressor should have an improved service life, reduced maintenance requirements, and at the same time high efficiency and wear resistance.
[0013] This problem is solved using a reciprocating compressor according to the independent claim. Advantageous embodiments are the subject of the dependent claims. R. 412009
[0014] - 2 -
[0015] According to a first aspect of the invention, a reciprocating compressor is provided, comprising a cylinder, a piston arranged to move linearly within the cylinder, an oil circuit for building up an oil film in a gap between an inner wall of the cylinder and an outer wall of the piston, an oil pump for pumping oil from an oil reservoir for the oil circuit, wherein the oil pump has a hollow body with a first opening and a second opening, wherein the first opening is connected to the oil reservoir, wherein the second opening is connected to the gap, wherein the hollow body has a reversibly deformable area between the first opening and the second opening, wherein a first valve is provided between the deformable area and the first opening, wherein the first valve allows an inflow of oil into the hollow body and makes a backflow of oil from the hollow body into the oil reservoir difficult or prevents it.wherein means are provided to cyclically reduce and increase the volume of the deformable area, wherein, by means of a cyclical change in the volume of the deformable area, oil from the oil reservoir can be conveyed through the first opening via the first valve into the gap.
[0016] This allows, for example, the technical advantage of providing an improved reciprocating compressor. The proposed reciprocating compressor offers the particular advantage that an oil film can be built up in a gap between the inner and outer walls of the cylinder using a pistonless oil pump. For this purpose, the oil pump has a hollow body with a first opening, a second opening, a deformable central section, and a first valve that allows oil to flow into the hollow body and restricts or prevents backflow. Furthermore, means are provided to cyclically decrease and increase the volume of the deformable section. This cyclical change in the volume of the deformable section enables a pumping action for the oil pump, even without an additional piston in the hollow body.The deformable section allows oil to be transported from the oil reservoir through the first opening, via the first valve, to the second opening. Consequently, the deformable section enables the oil to build up an oil film into the gap R. 412009.
[0017] - 3 - can be promoted. This allows the component size of the proposed piston compressor to be reduced, resulting in lower manufacturing and maintenance costs.
[0018] In another embodiment, the first valve is designed as a check valve, in particular as a ball valve or disc valve.
[0019] This allows, for example, the technical advantage of making the transfer of oil from the first opening to the second opening in the oil circuit more efficient. Using a check valve, and in particular a disc valve or ball valve, the backflow of oil from the hollow body into the oil reservoir can be made particularly difficult or prevented.
[0020] In a further embodiment, a second valve is provided between the deformable area and the second opening, wherein the second valve allows oil to drain from the hollow body via the second opening and makes it difficult or impossible for oil to flow back into the hollow body via the second opening.
[0021] This allows, for example, the technical advantage of further increasing the efficiency of the reciprocating compressor. The second valve can advantageously be used to impede or prevent the backflow of oil from the second opening into the hollow body, thereby improving the supply of oil to the oil circuit.
[0022] In another embodiment, the second valve is designed as a check valve, in particular as a disc valve or ball valve.
[0023] This allows, for example, the technical advantage of making the oil pump for the reciprocating compressor particularly efficient. By using a check valve, and especially a disc valve or ball valve, the backflow of oil from the second opening into the hollow body can be made particularly difficult or prevented. R. 412009
[0024] - 4 - In a further embodiment, the deformable area is arranged between the piston and a housing part, whereby a reciprocating movement of the piston generates a cyclic change in volume. The deformable area is geometrically designed such that, after being loaded by the piston and the resulting volume change of the deformable area, the deformable area returns to its original geometry when the load is removed. For this purpose, the deformable area is particularly balloon-like in design. Advantageously, the deformable area consists of a plastic, in particular an elastomer. A load can be understood as a mechanical force that deforms the deformable area. A release can be understood as the removal of the applied mechanical force.The geometry can be described as balloon-like in that a cross-sectional area in the middle of the deformable area is larger than cross-sectional areas at an upper end region and a lower end region.
[0025] This allows, for example, the technical advantage of achieving particularly good pumping performance for the oil pump and a more compact design for the reciprocating compressor. By positioning the deformable section between the piston and a housing component of the reciprocating compressor, the cyclical change in the volume of the deformable section can be generated by the piston. Furthermore, a particularly balloon-like design can efficiently increase the oil delivery rate using the hollow body. By using a plastic, especially an elastomer, the deformation of the deformable section can be optimized and achieved with minimal force.
[0026] In a further embodiment, the deformable area comprises a pressure diaphragm and a base body, wherein the base body and the pressure diaphragm enclose the variable volume, and wherein the cyclic change of volume can be generated by means of a back-and-forth movement of the pressure diaphragm. The pressure diaphragm can be understood, in particular, as an impermeable, movable component that simultaneously serves to transmit force and to seal the volume. R. 412009
[0027] - 5 - In a further embodiment, the pressure diaphragm of the deformable area is connected to the piston on a first side, whereby the piston can be used to generate the back-and-forth movement of the pressure diaphragm.
[0028] This allows, for example, the technical advantage of being able to fully control the deformation of the deformable area using the piston. Thus, the cyclical change in volume can be controlled by a connection between the pressure diaphragm and the piston. This also allows the pressure diaphragm to be demolded again, or deformed in a different direction.
[0029] In a further embodiment, the first opening is provided in a first region of the hollow body and the second opening is provided in a second region of the hollow body, wherein the deformable region is arranged between the first region and the second region, wherein the first region and the second region are tubular with a first cross-section and a second cross-section, wherein the first and second cross-sections are smaller than a third cross-section of the deformable region.
[0030] This allows, for example, the technical advantage of further improving the extraction of oil from the oil reservoir. The tubular design of the first and second sections facilitates improved oil flow within the hollow body. Furthermore, a change in volume between the deformable section and the first and second sections can advantageously accelerate the oil flow. This is achieved particularly by using smaller cross-sections for the first and second sections.
[0031] The invention is explained in more detail below using exemplary embodiments. These include:
[0032] Fig. 1 shows a reciprocating compressor according to a first exemplary embodiment, R. 412009
[0033] - 6 -
[0034] Fig. 2 shows a first exemplary embodiment of an oil pump for the reciprocating compressor,
[0035] Fig. 3 shows a second exemplary embodiment of the oil pump for the reciprocating compressor,
[0036] Please note that the figures are schematic only and not to scale. Therefore, components and elements shown in the figures may be exaggerated in size or reduced in size for clarity.
[0037] Fig. 1 shows a reciprocating piston compressor 10 according to a first exemplary embodiment.
[0038] The reciprocating compressor 10 comprises a cylinder 11 and a piston 15, which is arranged to move linearly within the cylinder 11. The reciprocating compressor 10 is intended for use in refrigeration equipment. For example, the reciprocating compressor 10 can be used in a refrigerator or a freezer. In particular, the reciprocating compressor 10 can be used to pump a cooling medium for a cooling circuit.
[0039] For clarity, cylinder 11 and piston 15 are shown in a sectional view. Piston 15 is arranged to move linearly within cylinder 11. The linear movement of piston 15 is schematically represented by a first arrow 6. The reciprocating compressor 10 also includes an oil circuit 1 for building up an oil film 2 in a gap 5. The gap 5 is formed between an inner wall 12 of cylinder 11 and an outer wall 16 of piston 15. The oil film 2 in the gap 5 serves to lubricate piston 15 located in cylinder 11.
[0040] The reciprocating compressor 10 also includes an oil pump 20. The oil pump 20 serves to pump oil 3 from an oil reservoir 4 for the oil circuit 1. R. 412009
[0041] - 7 -
[0042] The oil pump 20 comprises a hollow body 30 with a first opening 31 and a second opening 32. The first opening 31 is connected to the oil reservoir 4. In this embodiment, the first opening 31 is located within the oil reservoir 4. The second opening 32 is connected to the gap 5. By way of example, the second opening 32 is connected to the gap 5 via a tube 7. Between the first opening 31 and the second opening 32, the hollow body 30 has a reversibly deformable region 40.
[0043] The deformable section 40 is exemplary in its balloon-like form and is arranged between a first section 41 and a second section 42 of the hollow body 30. In this embodiment, the first section 41 and the second section 42 are exemplary tubular in shape. The first opening 31 is located in the first section 41 and the second opening 42 is located in the second section 42. A first valve 35 is provided between the deformable section 40 and the first opening 31. The first valve 35 allows oil 3 to flow into the hollow body 30 and prevents or hinders the backflow of oil 3 from the hollow body 30 into the oil reservoir 4. Furthermore, a second valve 36 can be provided between the deformable section 40 and the second opening 32. The second valve 36 allows oil 3 to drain from the hollow body 30 via the second opening 32 and makes it difficult or impossible for oil 3 to flow back into the hollow body 30 via the second opening 32.For this purpose, the first valve 35 and the second valve 36 can, for example, be check valves. In particular, the valves 35 and 36 can be designed as disc valves or ball valves.
[0044] Furthermore, means are provided to deform the deformable area 40 and thereby cyclically reduce and increase its volume. For example, the deformable area 40 can be deformed using an additional actuator (not shown). By means of the cyclical change in the volume of the deformable area 40, oil 3 can be conveyed from the oil reservoir 4 through the first opening 31, through the first valve 35, and into the gap 5.
[0045] In this embodiment, the deformable area 40 is exemplified as being between the linearly movable piston 15 and a housing part 8 of the R. 412009.
[0046] - 8 -
[0047] A reciprocating compressor 10 is arranged. This allows the cyclic change in volume to be achieved with the piston 15, eliminating the need for an additional actuator. Using the cyclic volume change of the deformable area 40 generated by the piston 15, oil 3 can be pumped from the oil reservoir 4. Thus, when the deformable area 40 is deformed, oil 3 is pumped from the hollow body 30 through the second opening 32 to the gap. For this to occur, the geometry of the deformable area 40 is compressed under the force exerted by the piston 15. When the deformable area 40 returns to its original shape, oil 3 is pumped from the oil reservoir 4 through the first opening 31 into the hollow body 30. For this, the piston 15 retracts, and the compressed deformable area 40 can then return to its original shape due to the release of pressure.
[0048] Figures 2 and 3 below describe two exemplary embodiments of an oil pump 20 for the reciprocating compressor 10.
[0049] Fig. 2 shows a first exemplary embodiment of an oil pump 20 for the reciprocating compressor.
[0050] The oil pump 20 from Fig. 2 is essentially the same as the oil pump from Fig. 1.
[0051] The oil pump 20 has a hollow body 30 with a first opening 31 and a second opening 32. Between the first opening 31 and the second opening 32, the hollow body 30 has a deformable section 40. Furthermore, a first valve 35 is provided between the first opening 31 and the deformable section 40. The first valve 35 serves to allow oil 3 to flow into the hollow body 30 and to impede the backflow of oil 3 from the hollow body into the oil reservoir 4.
[0052] For example, the deformable area 40 is shaped like a balloon. The deformable area 40 can, for instance, consist of an elastomeric material. Furthermore, in this embodiment, the deformable area 40 is again provided between the first area 41 and the second area 42. The first and second areas 41, 42 can also be made of R. 412009.
[0053] - 9 - consist of an elastomer. It is also conceivable that the first region 41 and the second region 42 consist of a different material, for example a metal or a metal alloy. The first region 41 and the second region 42 are shown as tubular shapes by way of example. However, the first region 41 and the second region 42 can also have other geometric shapes.
[0054] The first region 41 and the second region 42 have a first cross-section 51 and a second cross-section 52, respectively. For example, the first and second cross-sections 51, 52 are smaller than a third cross-section 53 of the deformable region 40. This allows the oil 3 to be accelerated fluid-mechanically within the hollow body 30 by means of a volume change due to the different cross-sections 51, 52, 53.
[0055] The first valve 35 is arranged in the first section 41 and is designed, for example, as a check valve, in particular as a disc valve or ball valve. The second valve 36 is provided in the second section 42 by way of example. The second valve 36 again serves to allow oil 3 to drain from the hollow body 30 via the second opening 32 and to impede or prevent backflow of oil 3 through the second opening 32 into the hollow body 30. The second valve 36 can also be designed, for example, as a check valve, in particular as a disc valve or ball valve.
[0056] As an example, the deformable area 40 of the hollow body 30 is arranged between the piston 15 and a fixed housing part 8 of the reciprocating compressor. The deformation of the deformable area 40 can be generated by means of the piston 15. The deformable area 40 can, for example, be arranged at a first side 43 with an end region 17 of the piston 15.
[0057] The deformable area 40 can be deformed by means of a back-and-forth movement of the piston 15, which is exemplified by the first arrow 6. By arranging the piston 15 with its end region 17 on the first side 43 of the deformable area 40, the reversible deformation for volume change can be carried out particularly efficiently. R. 412009
[0058] - 10 -
[0059] Fig. 3 shows a second exemplary embodiment of the oil pump 20 for the reciprocating compressor.
[0060] The oil pump 20 corresponds in essential aspects to the oil pump from Fig. 2. To avoid repetition, not all components of the oil pump 20 will be discussed in full here.
[0061] The oil pump 20 has a hollow body 30 with a first opening 31 and a second opening 32. Between the first opening 31 and the second opening 32, the hollow body 30 has a deformable section 40. Furthermore, a first valve 35 is provided between the first opening 31 and the deformable section 40. The first valve 35 serves to allow oil 3 to flow from the hollow body 30 and to impede the backflow of oil 3 from the hollow body 30 into the oil reservoir 4.
[0062] By way of example, the deformable area 40 comprises a pressure diaphragm 45 and a base body 46. The base body 46 and the pressure diaphragm 45 enclose the variable volume. The deformable area 40 consists at least partially of a plastic, in particular an elastomer. In this embodiment, the pressure diaphragm 45 is made of a reversibly deformable plastic, in particular an elastomer. The reversibly deformable area 40 can, as shown in this embodiment, consist of two components. For example, the base body 46 together with the pressure diaphragm 45 can form the deformable area 40 of the hollow body 30. The base body 46 can, for example, have a U-profile in a sectional view. The pressure diaphragm 45 can be provided on an open side of the U-profile. Thus, the variable volume is enclosed by the base body 46 and the pressure diaphragm 45.The base body 46 can also be made of a plastic. The base body 46 can also be made of another material, for example, a metal or a metal alloy. The pressure diaphragm 45 can be understood in particular as an impermeable, movable component that simultaneously serves to transmit force and to seal the volume. R. 412009.
[0063] - 11 -
[0064] The deformable area 40 of the hollow body 30, in particular the pressure diaphragm 45, can, for example, be arranged on and connected to a piston (not shown) of the reciprocating compressor. The deformation of the pressure diaphragm 45 can be generated by means of the piston. The pressure diaphragm 45 can, for example, be connected to the end region of the piston at a first side 43. By means of a reciprocating movement of the piston, which is exemplified by the first arrow 6, the pressure diaphragm 45 can be reversibly deformed, and a pumping action for the oil pump 20 can be achieved through the cyclic change in volume.
[0065] Although the present invention has been described with reference to specific embodiments, a person skilled in the art can also implement embodiments that have not been disclosed or have only been partially disclosed, without deviating from the core of the invention.
Claims
R. 412009 - 12 - Claims 1. Reciprocating compressor (10), comprising: a cylinder (11), a piston arranged to be linearly movable within the cylinder (11). (15), an oil circuit (1) for building up an oil film (2) in a gap (5) between an inner wall (12) of the cylinder (11) and an outer wall (16) of the piston (15), an oil pump (20) for pumping oil (3) from an oil reservoir (4) for the oil circuit (1), wherein the oil pump (20) has a hollow body (30) with a first opening (31) and a second opening (32), wherein the first opening (31) is connected to the oil reservoir (4), wherein the second opening (32) is connected to the gap (5), wherein the hollow body (30) has a reversibly deformable area (40) between the first opening (31) and the second opening (31), wherein a first valve (35) is provided between the deformable area (40) and the first opening (31), wherein the first valve (35) provides an inlet of oil (3) into the hollow body (30) enables and a backflow of oil (3) from the hollow body (30) into the The oil reservoir (4) is made difficult or prevented, wherein means are provided to cyclically reduce and increase the volume of the deformable area (40), wherein, by means of a cyclic change in the volume of the deformable area (40), oil (3) can be conveyed from the oil reservoir (4) via the first opening (31) through the first valve (35) to the gap (5).
2. Reciprocating piston compressor (10) according to claim 1, R. 412009 - 13 - wherein the first valve (35) is designed as a check valve, in particular as a ball valve or disc valve.
3. Reciprocating piston compressor (10) according to claim 1 or 2, wherein a second valve (36) is provided between the deformable area (40) and the second opening (32), wherein the second valve (36) allows oil (3) to drain from the hollow body (30) via the second opening (32) and makes it difficult or prevents oil (3) from flowing back into the hollow body (30) via the second opening (32).
4. Reciprocating piston compressor (10) according to claim 3, wherein the second valve (36) is designed as a check valve, in particular as a disc valve or ball valve.
5. Reciprocating piston compressor (10) according to one of claims 1 to 4, wherein the deformable area (40) is arranged between the piston (15) and a housing part (8), wherein a cyclic change in volume can be generated by means of a reciprocating movement of the piston (15), wherein the deformable area (40) is geometrically designed such that, after a load from the piston (15) and the resulting change in volume of the deformable area (40), the deformable area (40) returns to its original geometry upon unloading, wherein the deformable area (40) is designed in a balloon-like manner for this purpose, and wherein the deformable area (40) is made of a plastic, in particular an elastomer.
6. Reciprocating compressor (10) according to one of claims 1 to 4, wherein the deformable area (40) has a pressure diaphragm (45) and a base body (46), wherein the base body (46) and the pressure diaphragm (45) enclose the variable volume, and wherein the cyclic change of the volume can be generated by means of a back-and-forth movement of the pressure diaphragm (45).
7. Reciprocating piston compressor (10) according to claim 6, wherein the pressure diaphragm (45) of the deformable area (40) is connected to the piston on a first side (43). R. 412009 - 14 - (15) is connected, whereby the piston (15) can be used to generate the back-and-forth movement of the pressure diaphragm (45).
8. Reciprocating piston compressor (10) according to one of claims 1 to 7, wherein the first opening (31) is in a first region (41) of the hollow body (30) is provided and wherein the second opening (32) is provided in a second region (42) of the hollow body (30), wherein the deformable region (40) is arranged between the first region (41) and the second region (42), wherein the first region (41) and the second region (42) are tubular in shape with a first cross-section (51) and second cross-section (52), wherein the first and second cross-sections (51, 52) are smaller than a third cross-section (53) of the deformable region (40).