Oscillating piston compressor

Abstract

The invention relates to an oscillating piston compressor with a cylinder housing (7), comprising an oscillating piston (1) which is accommodated in a working chamber (2) and is driven by an eccentric shaft (8), the oscillating piston (1) being equipped with a piston rod segment (11) which extends perpendicularly to the axis of rotation (S8) of the eccentric shaft (8); a low-pressure inlet channel (4), which opens into the working chamber (2), for the working medium to be compressed; a high-pressure outlet channel (5), which opens into the working chamber (2), for the compressed working medium; and a weighing element (3), which is equipped with a receiving area (33) for movably mounting the piston rod segment (11). The low-pressure inlet channel (4) is received in the weighing element (3), and the piston-side inflow surface is designed to be inclined relative to the low-pressure inlet channel.

Description

[0001] vibrating piston compressor

[0002] The present invention relates to a vibrating piston compressor according to the preamble of claim 1.

[0003] A oscillating piston compressor is a compressor in which an oscillating piston moves eccentrically. Therefore, oscillating piston compressors are also called rotary or recirculating compressors. The fluid to be compressed, for example a refrigerant, is compressed in a closed working chamber, also called a cylinder, compression chamber, or cylinder chamber, against the inner wall of which an eccentrically mounted oscillating piston moves.

[0004] The oscillating piston is freely mounted on the eccentric shaft. Guided by the piston's web within the cradle element (or between the cradle element components), it performs a kind of orbiting motion within the cylinder. Instead of "rolling," the oscillating piston makes frictional contact / glides along the cylinder wall. The cradle element (or its components) performs an oscillating angular movement.

[0005] The oscillating piston is usually mounted on an eccentric shaft, which is driven by a drive unit, for example an electric motor.

[0006] The aforementioned type of oscillating piston compressor can further be equipped with a weighing element, also called a pivoting bushing or pendulum bushing. The weighing element is rotatably mounted in the cylinder housing about a weighing element axis of rotation. The weighing element axis of rotation is aligned parallel to the eccentric shaft axis of rotation.

[0007] The oscillating piston is equipped with a piston rod segment, also called a piston guide web, which is slidably mounted in a receptacle for the piston rod segment in the cradle element. The piston rod segment is oriented radially to the axis of rotation of the cradle element or the axis of rotation of the eccentric shaft, allowing the piston rod segment to be moved longitudinally within the receptacle of the cradle element. This provides the oscillating piston with additional guidance, and the piston rod segment also typically separates the low-pressure chamber from the high-pressure chamber in the working chamber. Such an oscillating piston compressor is known, for example, from EP 0652373 Al or EP 0851125 Al. Furthermore, such an oscillating piston compressor is also known from JP1994147164A.

[0008] The working fluid to be compressed is drawn into the working chamber through the low-pressure inlet channel. It then strikes the oscillating piston almost radially. From a fluid mechanics perspective, this is not optimal. However, the structural constraints only allow for limited optimization of the channel design.

[0009] This is where the present invention comes in and aims to propose an improved oscillating piston compressor, in particular an oscillating piston compressor that can enable an improved flow of the fluid to be compressed into the working chamber.

[0010] According to the invention, this problem is solved by a oscillating piston compressor with the characterizing features of claim 1. Because the low-pressure inlet channel is incorporated into the cradle element and the piston-side flow surface is designed at an angle to the low-pressure inlet channel, improved flow of the fluid to be compressed into the working chamber is achieved. Furthermore, the need to integrate a low-pressure inlet channel into the cylinder housing is eliminated, ultimately resulting in production cost savings. The cradle element offers alternative, cost-effective options for providing the low-pressure inlet channel. The cradle element also provides flow-optimized possibilities for aligning the low-pressure inlet channel with a predetermined area of ​​the oscillating piston, which then becomes the flow area for the working fluid exiting the low-pressure inlet channel.

[0011] Further advantageous embodiments of the proposed invention arise in particular from the features of the dependent claims. The subject matter or features of the various claims can, in principle, be combined with one another in any way.

[0012] In an advantageous embodiment of the invention, the weighing element can be rotatably mounted about an axis of rotation in a receptacle in the cylinder housing, the axis of rotation of the eccentric shaft being aligned parallel to the axis of rotation of the weighing element. In a further advantageous embodiment of the invention, the low-pressure inlet channel can be configured parallel to the receptacle for the piston rod segment in the weighing element. This results in a production-wise simple combination for manufacturing the receptacle and the low-pressure inlet channel. With a suitable design of the weighing element, particularly as a two-part component, the low-pressure inlet channel and the receptacle for the piston rod segment can, for example, be manufactured in a single operation.

[0013] In a further advantageous embodiment of the invention, the weighing element can be composed of a component facing away from the high-pressure outlet channel and a component facing towards the high-pressure outlet channel, wherein the low-pressure inlet channel is formed as a groove in the component facing away from the outlet channel. A two-part weighing element offers advantages in terms of production technology; in particular, the receptacle for the piston rod segment and the low-pressure inlet channel in the weighing element can be easily manufactured, since the aforementioned machining surfaces in the respective component can be easily accessed with a suitable machining tool.

[0014] In a further advantageous embodiment of the invention, the oscillating piston may include on its outer surface a transition area facing the low-pressure inlet channel between the piston outer surface and the piston rod segment, wherein the low-pressure inlet channel terminates above the transition area, the transition area forming the piston-side flow surface. It is advantageous to provide the flow surface in the aforementioned transition area between the piston outer surface and the piston rod segment, since a transition between the circular oscillating piston and the piston rod segment extending radially from it is necessary in any case. Accordingly, the inclined flow surface should preferably be located in this area.

[0015] In a further advantageous embodiment of the invention, the transition area can be designed as a curved surface with a radius. A curved surface with a radius is particularly advantageous as an inflow surface. The radius depends essentially on the respective dimensions of the compressor, in particular the cylinder diameter, the width of the piston land, the diameter of the rocker element, the piston diameter, and the eccentricity. The radius is generally smaller than, equal to, or even larger than the rocker element diameter. The oscillating piston diameter is larger than the rocker element diameter (space requirements). Other kinematic configurations are also possible.

[0016] In a further advantageous embodiment of the invention, a recess for the piston rod segment can be provided, into which the tip of the piston rod segment can immerse. This recess is arranged above the receptacle for the piston rod segment and is further configured as a supply channel for the working medium to be compressed, and is in fluidic communication with the low-pressure inlet channel. The recess required for immersion during the movement of the piston rod segment is advantageously assigned a dual function, namely, that the recess is additionally used as a supply channel for the working medium to be compressed. It is particularly advantageous for the recess to be laterally extended so that a low-pressure inlet channel, which is typically arranged off-center, can be optimally supplied with the working medium to be compressed.

[0017] Further features and advantages of the present invention will become clear from the following description of preferred embodiments with reference to the accompanying figures. The elements or features of the various embodiments can, in principle, be combined with one another as desired. These show:

[0018] Fig. 1 shows a schematic sectional view of a oscillating piston compressor according to the prior art;

[0019] Fig. 2 shows a schematic sectional view of an embodiment of a vibrating piston compressor according to the invention;

[0020] Fig. 3 is an enlarged view according to section “A” from Fig. 2;

[0021] Fig. 4-7 shows a schematic representation of the operation of the vibrating piston compressor according to the invention;

[0022] Fig. 8-11 shows a first embodiment of the weighing element with low-pressure inlet channel in various perspective views;

[0023] Fig. 12-15 shows a second embodiment of the weighing element with low-pressure inlet channel in various perspective views;

[0024] Figs. 16-19 show a third embodiment of the weighing element with low-pressure inlet channel in various perspective views;

[0025] Fig. 20 shows a schematic sectional view of another embodiment of a vibrating piston compressor according to the invention.

[0026] The following reference symbols are used in the illustrations:

[0027] S3 Axis of rotation of the weighing element

[0028] S8 axis of rotation of the eccentric shaft

[0029] RI first radius

[0030] R2 second radius

[0031] 1 oscillating piston

[0032] 2 Working room / compressor room

[0033] 3 weighing element

[0034] 4 Low-pressure inlet channel (state of the art) 5 High-pressure outlet channel

[0035] 6 - free -

[0036] 7 Cylinder housing / compressor housing

[0037] 8 eccentric shaft

[0038] 11 Piston rod segment / piston guide web

[0039] 12 Ring

[0040] 31 Inlet-side component (of the weighing element)

[0041] 32 Outlet-side component (of the weighing element)

[0042] 33 Mounting for piston rod segment

[0043] 34 Low-pressure inlet channel in the weighing element

[0044] 51 Exhaust valve

[0045] 71 Mounting point for weighing element

[0046] 72 Clearance for piston rod segment

[0047] 72a Extension of the open space

[0048] 111 Transition area

[0049] 112 Transition area

[0050] Features and details described in connection with a method naturally also apply to the device according to the invention, and vice versa, so that the disclosure regarding the individual aspects of the invention always makes or can make reciprocal reference. Furthermore, any described method according to the invention can be carried out with the device according to the invention.

[0051] The terminology used herein serves only to describe certain embodiments and is not intended to limit the disclosure. As used herein, the singular forms "a" and "the" are intended to include the plural forms unless the context otherwise makes clear. It will also be clear that the expressions "indicates" and / or "indicating," when used in this description, specify the presence of the aforementioned features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated, listed elements.

[0052] Reference is first made in particular to Fig. 1. Here, a oscillating piston compressor according to the prior art is shown in a sectional view.

[0053] A oscillating piston compressor essentially comprises an oscillating piston 1 housed in a working chamber 2, which is driven by an eccentric shaft 8. The eccentric shaft 8 has an eccentric axis of rotation S8. The working chamber 2 is housed in a cylinder housing 7. The cylinder housing 7 can also be referred to as the compressor housing. The eccentric shaft 8 is preferably driven by an electric motor (not shown). However, other drive methods are also conceivable, for example, by means of the internal combustion engine of a motor vehicle. The eccentric shaft 8 has an eccentric axis of rotation S8.

[0054] The oscillating piston compressor further comprises a low-pressure inlet channel 4 for the working medium to be compressed, which opens into the working chamber 2, and a high-pressure outlet channel 5 for the compressed working medium, which also opens into the working chamber 2. The low-pressure inlet channel 4 for the working medium to be compressed can also be described as being in fluidic communication with the working chamber 2. Similarly, the high-pressure outlet channel 5 for the compressed working medium, which also opens into the working chamber 2, can also be described as being in fluidic communication with the working chamber 2.

[0055] Preferably, the fluid to be compressed, which can also be referred to as the working fluid, is a refrigerant. The oscillating piston compressor is therefore preferably part of an air conditioning system.

[0056] The oscillating piston compressor can be part of a refrigerant circuit or similar system, such as stationary refrigeration units for food, building air conditioning, air conditioning for passenger vehicles, and refrigerators for private use. Its use is conceivable not only in air conditioning systems but also in heat pumps, etc. Furthermore, the compressor proposed here can also be used to compress process gases or air. Other applications are also possible.

[0057] The oscillating piston compressor further comprises a weighing element 3. The weighing element 3 is rotatably mounted in a receptacle 71 within the cylinder housing 7. The weighing element 3 is rotatably mounted about a weighing element rotation axis S3. The weighing element rotation axis S3 is aligned parallel to the eccentric shaft rotation axis S8. The weighing element 3 is preferably composed of two components. In this respect, the weighing element 3 can be composed of a component 31 facing away from the high-pressure outlet channel 5 and a component 32 facing the high-pressure outlet channel 5. However, a one-piece design of the weighing element 3 is also conceivable.

[0058] The oscillating piston 1 essentially comprises a ring 12 and a piston rod segment 11, also called a piston guide web, which is slidably mounted in a receptacle 33 for the piston rod segment 11 in the cradle element 3. The receptacle 33 for the piston rod segment 11 is provided in the cradle element 3, preferably between the two components 31 and 32. The piston rod segment 11 is aligned radially with the axis of rotation S3 of the cradle element or the axis of rotation S8 of the eccentric shaft. The piston rod segment 11 can be displaced longitudinally in the receptacle 33 in the cradle element 3. The direction of displacement is indicated by the double arrow in the piston rod segment 11.

[0059] The piston rod segment 11 provides additional guidance to the oscillating piston 1 and also separates the low-pressure chamber 4 from the high-pressure chamber 5 in the working chamber 2.

[0060] To allow sufficient displacement, a clearance 72 is provided for the piston rod segment 11, into which the tip of the piston rod segment 11 can immerse. The clearance 72 is preferably located above the receptacle 31 for the piston rod segment 11, i.e., particularly on the side facing away from the working chamber 2. The ring 12 itself has a oscillating piston outer surface that faces the inner wall of the working chamber 2. The ring 12, or the oscillating piston outer surface, serves in particular as part of the oscillating piston 1, with which the working medium to be compressed, in particular the refrigerant, is compressed. It can be seen that, according to the prior art, the low-pressure inlet channel 4 and the outlet channel 5 are housed in the cylinder housing 7. The working medium is drawn into the working chamber 2 through the low-pressure inlet channel 4. In doing so, it impinges almost radially on the oscillating piston 1. From a fluid mechanics perspective, this is not optimal.However, the structural constraints only allow for limited optimization of the channel routing.

[0061] Particular reference is made below to Figures 2 to 20, which show a vibrating piston compressor according to the invention or details of a vibrating piston compressor according to the invention.

[0062] First, particular reference is made to Figures 2 and 3.

[0063] According to the invention, the low-pressure inlet channel 34, or at least a section of the low-pressure inlet channel, is arranged in the cradle element 3. Furthermore, the piston-side flow surface, i.e., the surface of the oscillating piston 1 onto which the working medium flowing in through the low-pressure inlet channel 34 strikes the oscillating piston 1, is oriented obliquely relative to the low-pressure inlet channel 34. The oblique flow direction on the piston-side flow surface results in less back pressure.

[0064] Figures 2 and 3 also show that the low-pressure inlet channel 34 is designed parallel to the receptacle 33 of the piston rod segment 11 in the cradle element. Essentially, the low-pressure inlet channel 34 is arranged off-center, i.e., next to the receptacle 33 for the piston rod segment 11.

[0065] It is further evident that transition areas exist between the outer surface of the oscillating piston and the piston rod segment 11, in particular a first transition area 111 between the outer surface of the oscillating piston and the piston rod segment 11, which faces the inlet-side component 31 of the weighing element 3, and a second transition area 112 between the outer surface of the oscillating piston and the piston rod segment 11, which faces the outlet-side component 32 of the weighing element 3. Preferably, the surface of the oscillating piston onto which the working medium flowing in through the low-pressure inlet channel 34 impinges upon the oscillating piston, i.e., the flow area, is the transition area 111.

[0066] The transition area 111, or the inlet surface, can be designed as a curved surface with a radius R. Other shapes are also conceivable. This design can help ensure that the incoming working fluid flows not perpendicularly onto a flat surface, but onto a curved surface that acts like a fluid guide plate. This can improve the flow of fluid into the working chamber 2, in particular by reducing back pressure. The radius depends primarily on the dimensions of the compressor, especially the cylinder diameter, the width of the piston land, the diameter of the rocker element, the piston diameter, and the eccentricity. The radius is generally smaller than, equal to, or even larger than the rocker element diameter. The oscillating piston diameter is larger than the rocker element diameter (space requirements). Other kinematic configurations are also possible.

[0067] The free space 72 for the movement of the piston rod segment 11 above the weighing element 3 can also be used as a supply channel for the working medium to be compressed. For this purpose, the free space 72 is designed to be in fluidic connection with the low-pressure inlet channel 34. Fluidic connection here refers to a connection for the transfer of the fluid or working medium.

[0068] Provided that the low-pressure inlet channel 34 is arranged next to the centrally located piston rod segment 11, the free space 72 can be provided with an off-center extension 72a that extends over the low-pressure inlet channel 34. The low-pressure inlet channel 34 in the weighing element 3 can be made wider.

[0069] Particular reference is made below to Figures 4 to 7. Figures 4 to 7 schematically illustrate a compaction process.

[0070] Figure 4 shows the position of the oscillating piston 1 at TDC, i.e., top dead center. The arrow in the oscillating piston 1 symbolizes the direction of rotation. An outlet valve 51 on the outlet channel 5 is closed. In Figure 5, the arrow in the low-pressure inlet channel 34 symbolizes that the working medium to be compressed flows through the inlet channel 34 in the weighing element 3 into the working chamber 2. The outlet valve 51 on the outlet channel 5 is closed. The oscillating piston 1 continues to rotate in the direction of the arrow.

[0071] In Fig. 6, the arrow in the outlet channel 5 symbolizes that the working medium to be compressed flows out of the working chamber 2 through the outlet channel 5. The outlet valve 51 on the outlet channel 5 is open. The oscillating piston 1 continues to rotate in the direction of the arrow. The working medium to be compressed continues to flow into the working chamber 2 through the low-pressure inlet channel 34.

[0072] In Fig. 7, the arrow in the outlet channel 5 symbolizes that the working medium to be compressed flows out of the working chamber 2 through the outlet channel 5. The outlet valve 51 on the outlet channel 5 is open. The oscillating piston 1 continues to rotate in the direction of the arrow. The working medium to be compressed continues to flow into the working chamber through the low-pressure inlet channel 34.

[0073] Further details of the compression process in a oscillating piston compressor are sufficiently known to the expert.

[0074] Particular reference is made below to Figures 8 to 19. Figures 8 to 19 show various embodiments of the weighing element 3 or weighing element component 31 in different perspective views. The weighing element 3, in particular the weighing element component 31, as such, can be designed with a groove or channel which is open towards the piston rod segment 11, the groove then forming the low-pressure inlet channel 34. Advantageously, the side areas or

[0075] The inner surfaces of channel 34 are designed to be straight and optimized for airflow.

[0076] Figures 8 to 11 show a first embodiment of a weighing element component 31 with a groove for forming a low-pressure inlet channel 34 in various perspective views. The low-pressure inlet channel 34 is particularly visible.

[0077] Figures 12 to 15 show a second embodiment of a weighing element component 31 with a groove for forming a low-pressure inlet channel 34 in various perspective views. The embodiment shown here is characterized in particular by a straight rectangular channel as the low-pressure inlet channel 34. For further details, reference can be made to the descriptions of the embodiment according to Figures 8 to 11.

[0078] Figures 16 to 19 show a third embodiment of a weighing element component 31 with a groove for forming a low-pressure inlet channel 34 in various perspective views. The embodiment shown here is characterized in particular by a curved rectangular channel as the low-pressure inlet channel 34. For further details, reference can be made to the descriptions of the embodiment according to Figures 8 to 11.

[0079] Reference is made below to Fig. 20.

[0080] Figure 20 shows a sectional view of a oscillating piston compressor according to the invention. Here, too, the low-pressure inlet channel 34 is provided in the cradle element 3. Furthermore, the free space 72 for the immersion of the piston rod segment 11 is enlarged, such that an enlarged free space 72a is provided above the low-pressure inlet channel 34. As already explained above, the free space 72 serves not only to allow the piston rod segment to immerse itself in the free space 72 during its movement, but also as a supply of working fluid to be compressed to the low-pressure inlet channel 34 in the cradle element 3. Since the low-pressure inlet channel 34 is generally arranged off-center in the cradle element 3, the enlarged recess at this point allows for improved flow characteristics of the fluid to be compressed into the low-pressure inlet channel 34.

Claims

Claims 1. Oscillating piston compressor with a cylinder housing (7), comprising - a vibrating piston (1) received in a working space (2) which is driven by an eccentric shaft (8), wherein the vibrating piston (1) is equipped with a piston rod segment (11) which extends perpendicular to the axis of rotation (S8) of the eccentric shaft (8), - a low-pressure inlet channel (4 or 34) leading into the working space (2) for the working medium to be compressed, - a high-pressure outlet channel (5) leading into the working chamber (2) for the compressed working medium, - a weighing element (3) which is equipped with a receptacle (33) for the slidable bearing of the piston rod segment (11), characterized in that the low-pressure inlet channel (34) is received in the weighing element (3) and the piston-side flow surface is designed obliquely opposite the low-pressure inlet channel.

2. Oscillating piston compressor according to claim 1, characterized in that the weighing element (3) is rotatably mounted about an axis of rotation (S3) in a receptacle (71) in the cylinder housing (7), wherein the axis of rotation (S8) of the eccentric shaft (8) is aligned parallel to the axis of rotation (S3) of the weighing element (3).

3. Oscillating piston compressor according to at least one of the preceding claims, characterized in that the low-pressure inlet channel (34) is designed parallel to the receiving (33) of the piston rod segment (11) in the cradle element.

4. Oscillating piston compressor according to at least one of the preceding claims, characterized in that the weighing element (3) is composed of a component (31) facing away from the high-pressure outlet channel (5) and a component (32) facing the high-pressure outlet channel (5), wherein the low-pressure inlet channel (4) is formed as a groove in the component (31) facing away from the high-pressure outlet channel.

5. Oscillating piston compressor according to at least one of the preceding claims, characterized in that the oscillating piston (1) comprises on its piston outer side a transition area (111) facing the low-pressure inlet channel (34) between the piston outer side and the piston rod segment (11), wherein the The low-pressure inlet channel (34) ends above the transition area (111), the transition area (111) forming the piston-side flow surface.

6. Oscillating piston compressor according to at least one of the preceding claims, characterized in that the transition area (111) is designed as a curved surface with a radius R.

7. Oscillating piston compressor according to at least one of the preceding claims, characterized in that a free space (72) is provided for the piston rod segment (11) into which the tip of the piston rod segment (11) can immerse, wherein the free space (72) is arranged above the receptacle (31) for the piston rod segment (11), wherein the free space (72) is further designed as a supply channel for the working medium to be compressed and is in fluidic communication with the low-pressure inlet channel (34).

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