Rotary piston compressor with medium-pressure inlet

Abstract

Oscillating piston compressor (1) with medium pressure inlet (2), comprising in a housing (4) a cylinder (5) with a oscillating piston (3), wherein the oscillating piston (3) is rotatably mounted on an eccentric (6) of a drive shaft (7) and comprises a separating slide (8) rigidly connected to the oscillating piston (3), a pivot bushing (9) rotatably mounted in the housing (4) for linear guidance of the separating slide (8) in a separating slide guide (10), a low-pressure inlet (11) which is operatively connected to an inlet chamber (5a) in the cylinder (5), a medium pressure inlet (2) which is operatively connected to an outlet chamber (5b) in the cylinder (5), wherein the medium pressure inlet (2) comprises a first section (2a) with a check valve (13) in the housing (4), a second section (2b) in the oscillating bushing (9) and a third section (2c) in the separating slide (8), and a high-pressure outlet (12) which is operatively connected to the outlet chamber (5b) in the cylinder (5).

Description

[0001] The present invention relates to a rotary piston compressor designed as a oscillating piston compressor for the compression of refrigerant, in which the separating slide is rigidly connected to the oscillating piston and supported in the housing via a oscillating bushing.

[0002] Rotary piston machines are known from the prior art, particularly those designed as rotary piston compressors or oscillating piston compressors. These rotary piston machines comprise a cylinder and a rotary piston housed within a casing. The rotary piston is mounted eccentrically with respect to its drive shaft and rests against the cylinder wall on one side. The rotary piston rotates eccentrically to the drive shaft and remains in constant contact with the cylinder wall within the casing during operation of the rotary piston compressor, or rather, forms a very small sealing gap with the casing. Furthermore, a separating valve is provided, by means of which the remaining crescent-shaped cylinder chamber is divided into two cylinder chambers, in particular an inlet chamber operatively connected to an inlet and an outlet chamber operatively connected to an outlet.The rotation of the rotary piston and the separation of the cylinder chamber cyclically change the volumes of the intake chamber and the exhaust chamber.

[0003] If, in a rotary piston compressor, the separating disc, guided longitudinally within the housing, is pressed against the rotary piston by a housing-side spring, and the piston itself can rotate a full revolution about its axis of rotation, then it is a rotary piston compressor. If, in a rotary piston compressor, the separating disc is rigidly connected to the rotary piston and guided longitudinally within a separate, rotatable guide within the housing, or if a separating vane is rigidly connected to the housing and guided longitudinally by a bushing rotatable within the rotary piston, and the piston can therefore only oscillate through a limited angle about its axis of rotation, then it is a oscillating piston compressor.

[0004] German patent application DE 24 09 270 A discloses a rotary piston compressor with a separating slide valve, in which the outlet is formed by a recess in the separating slide valve. The outlet cross-section is controlled by actuating the spring-loaded separating slide valve.

[0005] Patent GB 390,443 A discloses a rotary piston compressor with a separating slide for separating a suction side from a pressure side, in which inlet control is achieved by means of the separating slide. For this purpose, the separating slide has a pocket by means of which, depending on the position of the separating slide, the associated inlet channel is fluidly connected to the associated inlet chamber of the rotary piston compressor. The outlet is controlled by a spring-loaded pressure valve.

[0006] Patent DE 355192 A discloses a rotary piston compressor of the generic type, designed as a oscillating piston compressor, in which the outlet channel is at least partially guided in the separating slide of the rotary piston and, together with a slotted oscillating sleeve in the compressor housing, forms a controlled outlet. Accordingly, it is known that a slot-controlled refrigerant channel is formed in a part of the piston or in the separating slide.

[0007] From European patent application EP 1 953 337 A1, a rotary piston expander is known which has a first inlet and a second inlet. The first inlet is radially directed into the working chamber. The second inlet is axially directed into the working chamber. The second inlet, located downstream of the first inlet, is controlled by an end-face overlap of the piston with the housing.

[0008] Patent JPS 61-56438 B2 discloses a rotary piston compressor with one inlet and one outlet. A medium-pressure inlet is provided in the cylinder housing between the inlet and the outlet, which is controlled by the piston face according to the overlap resulting from the piston's rotation.

[0009] US patent 3,671,146 A discloses a vane compressor in which the inlet and outlet are formed via channels in the separating slide and further via channels in the piston. The inlet and outlet are controlled by the position of the separating slide relative to the piston.

[0010] US patent 6,270,329 B1 discloses a generic oscillating piston compressor in which the separating slide, rigidly connected to the piston, is guided in a oscillating bushing in the housing. A channel to a small compensating volume in the housing is provided in the oscillating bushing. This small compensating volume serves to reduce pressure fluctuations. Access to the compensating volume is controlled via the oscillating bushing, thus further reducing compression losses.

[0011] Patent DE 10 2012 208 992 B4 discloses a heating / cooling circuit with a refrigerant compressor. The refrigerant compressor has a low-pressure inlet through which a gaseous refrigerant at low pressure is drawn in, and a high-pressure outlet through which the compressed and heated refrigerant is pumped within the heating / cooling circuit. To provide various operating programs for electric vehicles, in particular heating, cooling, mixed operation, and defrosting of an outdoor heat exchanger, the refrigerant compressor further has a medium-pressure inlet through which a gaseous refrigerant at a medium pressure level is supplied to the compressor.

[0012] German patent application DE 10 2021 132 942 A1 discloses an air conditioning compressor for compressing refrigerant. The compressor is designed as a rotary or oscillating piston compressor with a housing-mounted baffle and has a main inlet for supplying a refrigerant at low pressure, an outlet for the refrigerant compressed to high pressure, and a medium-pressure inlet arranged between the main inlet and the outlet. In one embodiment, the medium-pressure inlet is formed within the housing-mounted baffle, with the control of the medium-pressure inlet being effected via the guide sleeve of the baffle, which is integrated into the piston. The medium-pressure inlet allows refrigerant compressed to medium pressure to enter the ongoing refrigerant compression process, thus enabling, for example, the connection of two refrigeration circuits of an electric vehicle.

[0013] Patent DE 571 915 A describes a machine with a piston mounted on a crankshaft and moving eccentrically within a cylindrical housing, and a fixed abutment to which it is connected. The abutment, guided in a rotary valve mounted in the housing, performs a reciprocating motion to exert a suction and pressure effect. Two channels are arranged in the abutment, one end of which opens into the slot provided for the abutment in the rotary valve. The opposite ends of the channels are connected to the suction chamber and the pressure chamber, respectively. Furthermore, each channel contains a valve corresponding to the suction and pressure effect.

[0014] The object of the invention is to provide a oscillating piston compressor with an improved intermediate pressure inlet.

[0015] The problem is solved by the oscillating piston compressor with medium-pressure inlet according to the features of claim 1. Advantageous further developments are described in the dependent claims and the exemplary embodiments.

[0016] The invention provides an advantageous oscillating piston compressor with an improved intermediate pressure inlet, with which refrigerant can be compressed in a refrigerant circuit.

[0017] The oscillating piston compressor comprises a cylinder within a housing and an oscillating piston driven by an eccentric shaft. The oscillating piston is rigidly connected to a sliding valve, which in turn is mounted for linear displacement within a oscillating bushing rotatably housed in the housing. The oscillating bushing incorporates a sliding valve guide within which the sliding valve is linearly guided. The oscillating piston has a smaller diameter than the cylinder and forms a sealing gap relative to the cylinder in the direction of the drive shaft's eccentricity, or it is in sliding contact with the cylinder. During operation, the oscillating piston rotates within the cylinder and undergoes only a slight rotation relative to its own axis of rotation, as it is rotatably mounted on the eccentric of the drive shaft and supported in the housing by the sliding valve and the oscillating bushing.As a result, the oscillating bushing also performs a rotation in the sense of an oscillation during operation of the oscillating piston compressor.

[0018] The cylinder is operatively connected to a low-pressure inlet, a medium-pressure inlet, and a high-pressure outlet. Between the cylinder and the oscillating piston, specifically between the inner surface of the cylinder and the outer surface of the oscillating piston, a predominantly crescent-shaped working chamber for the refrigerant is formed. This chamber is divided by the separating valve on the oscillating piston into an inlet chamber operatively connected to the low-pressure inlet and an outlet chamber operatively connected to the medium-pressure inlet and the high-pressure outlet.

[0019] Through the medium-pressure inlet, refrigerant is supplied to the reciprocating piston compressor at a pressure level in the compression chamber that lies between the pressure level of the low-pressure inlet and the pressure level of the high-pressure outlet.

[0020] In an advantageous manner according to the invention, the intermediate pressure inlet is provided by means of an inlet channel which extends from the housing of the oscillating piston compressor through the oscillating bushing and through the separating slide of the oscillating piston and comprises three successively interconnected intermediate pressure inlet channel sections. For this purpose, a first section of the intermediate pressure inlet channel is located in the housing of the oscillating piston compressor, a second section of the intermediate pressure inlet channel is located in the oscillating bushing, and a third section of the intermediate pressure inlet channel is located in the separating slide of the oscillating piston, wherein the third intermediate pressure inlet channel opens into the outlet chamber.

[0021] Depending on the angular position of the oscillating piston relative to the housing, a relative position is established between the separating slide and the oscillating bushing, and further a relative position of the oscillating bushing in the housing, resulting in a controlled fluid connection between the first, second and third sections of the medium-pressure inlet channel or no fluid connection between the first, second and third sections of the medium-pressure inlet channel.

[0022] Within a predetermined range of the angular position of the oscillating piston relative to the housing and, via the separating slide, also within a predetermined range of the angular position of the oscillating bushing relative to the housing and the displacement of the separating slide in the separating slide guide in the oscillating bushing, a continuous fluid connection results from the first section of the medium-pressure inlet channel in the housing of the oscillating piston compressor via the second section of the medium-pressure inlet channel in the oscillating bushing and the third section of the medium-pressure inlet channel in the separating slide of the oscillating piston into the compression chamber of the oscillating piston compressor.

[0023] A fluid connection is established when the sections are aligned with each other, whereby the flow cross-sections overlap in the area of ​​the transitions from the first section of the medium-pressure inlet channel in the housing to the second section of the medium-pressure inlet channel in the oscillating sleeve, and from the second section of the medium-pressure inlet channel in the oscillating sleeve to the third section of the medium-pressure inlet channel in the separating valve, depending on the angular position of the oscillating piston relative to the housing. This allows the coolant to flow into the compression chamber at the medium-pressure level, as long as the medium-pressure level is higher than the pressure level in the compression chamber.

[0024] The control of the intermediate pressure inlet results from the overlap of the flow cross-sections in the area of ​​a first transition from the first section of the intermediate pressure inlet channel in the housing to the second section of the intermediate pressure inlet channel in the oscillating sleeve, and in the area of ​​a second transition from the second section of the intermediate pressure inlet channel in the oscillating sleeve to the third section of the intermediate pressure inlet channel in the separating slide. The relative positions of the intermediate pressure inlet channel sections and the design of the respective flow cross-section of the sections in the respective transition area provide control of the intermediate pressure inlet.

[0025] The control of the intermediate pressure inlet is achieved particularly advantageously by the overlap of the flow cross-sections in the region of the first transition from the first section of the intermediate pressure inlet channel in the housing to the second section of the intermediate pressure inlet channel in the vibrating sleeve. The control of the intermediate pressure inlet is also achieved particularly advantageously by the overlap of the flow cross-sections in the region of the second transition from the second section of the intermediate pressure inlet channel in the vibrating sleeve to the third section of the intermediate pressure inlet channel in the separating slide.

[0026] The control of the intermediate pressure inlet is achieved in a particularly advantageous manner by the overlap of the flow cross-sections in the area of ​​the first transition from the first section of the intermediate pressure inlet channel in the housing to the second section of the intermediate pressure inlet channel in the oscillating sleeve, wherein the overlap is further present in the area of ​​the second transition from the second section of the intermediate pressure inlet channel in the oscillating sleeve to the third section of the intermediate pressure inlet channel in the separating slide over the entire rotation of the oscillating sleeve.

[0027] The control of the intermediate pressure inlet is achieved in a particularly advantageous manner by the overlap of the flow cross-sections in the area of ​​the second transition from the second section of the intermediate pressure inlet channel in the oscillating sleeve to the third section of the intermediate pressure inlet channel in the separating slide, wherein the overlap is further present in the area of ​​the transition from the first section of the intermediate pressure inlet channel in the housing to the second section of the intermediate pressure inlet channel in the oscillating sleeve over the entire rotation of the oscillating sleeve.

[0028] By adjusting the design of the overlaps depending on the angular position of the oscillating piston and bushing, the pressure range at which coolant can flow into the exhaust chamber via the medium-pressure inlet can be influenced. If the fluid connection from the medium-pressure inlet to the exhaust chamber is established at an early stage of compression in the exhaust chamber, coolant can flow in with only a slight pressure increase compared to the coolant pressure at the low-pressure inlet, whereas at a later stage of compression in the exhaust chamber, coolant can flow in with a comparatively higher pressure increase.

[0029] In a particularly advantageous manner, the second section of the medium-pressure inlet channel in the vibrating bushing is radially oriented, such that it extends from the outer surface of the vibrating bushing to a flank surface of the separating slide guide. In a very advantageous manner, the flow cross-section of the second section of the medium-pressure inlet channel in the vibrating bushing at the outer surface is larger than the flow cross-section of the second section of the medium-pressure inlet channel in the vibrating bushing at the flank surface.

[0030] To prevent coolant from flowing back out of the compression chamber, a check valve is arranged in the medium-pressure inlet channel. If the pressure level in the compression chamber exceeds the medium-pressure level, the check valve closes and the fluid connection in the medium-pressure inlet channel is interrupted. Advantageously, the check valve is arranged in the first section of the medium-pressure inlet channel and thus in the housing of the oscillating piston compressor. Advantageously, the check valve is arranged in the second section of the medium-pressure inlet channel and thus in the oscillating bushing of the oscillating piston compressor. Advantageously, the check valve is arranged in the third section of the medium-pressure inlet channel and thus in the oscillating piston of the oscillating piston compressor.

[0031] An exemplary first embodiment of a oscillating piston compressor 1 according to the invention with a medium-pressure inlet 2 is shown here. The accompanying figures show: Fig. 1a, Fig. 1b, Fig. 1c and Fig. 1d: each a schematic representation of the oscillating piston compressor 1 with medium pressure inlet 2 at different positions of an oscillating piston 3.

[0032] In this version, shown in Fig. 1a - Fig. Figure 1d states that the advantageous oscillating piston compressor 1 with a medium-pressure inlet 2 comprises a cylinder 5 with an oscillating piston 3 in a housing 4. The oscillating piston 3 is rotatably mounted on an eccentric 6 of a drive shaft 7 and includes a separating slide 8 rigidly connected to the oscillating piston 3. The separating slide 8, in turn, is linearly displaceable relative to the oscillating bushing 9 in a separating slide guide 10 in the sense of a support bearing via a oscillating bushing 9 rotatably mounted in the housing 4. Furthermore, a low-pressure inlet 11, operatively connected to the cylinder 5, in particular to an inlet chamber 5a, a medium-pressure inlet 2, operatively connected to the cylinder 5, in particular to an outlet chamber 5b, and a high-pressure outlet 12, operatively connected to the cylinder 5, in particular to the outlet chamber 5b, are arranged in the housing 4.

[0033] The medium-pressure inlet 2 extends from the housing 4 via the oscillating bushing 9 and the separating valve 8 to the cylinder 5 as a medium-pressure inlet channel, comprising a first section 2a, a second section 2b, and a third section 2c, and opens into the cylinder 5. The first section 2a is located in the housing 4 and includes a check valve 13. The second section 2b is located in the oscillating bushing 9. The second section 2b is designed such that the flow cross-section decreases in the direction of flow of the incoming coolant. The third section 2c is located in the separating valve 8 of the oscillating piston 3.

[0034] Depending on the angular position of the oscillating piston 3 in the cylinder 5, and thus also depending on the angular position of the oscillating bushing 9 relative to the housing 4, the intermediate pressure inlet 2 is fluidly connected to the cylinder 5, in particular to the outlet chamber 5b in the cylinder 5, if there is an overlap of the flow cross-sections in a first transition region 2ab from the first section 2a to the second section 2b and in a second transition region 2bc from the second section 2b and the third section 2c, and the coolant pressure in the intermediate pressure inlet 2 is higher than the coolant pressure in the outlet chamber 5b, and thus the check valve 13 is open, as shown in Fig. 1a and Fig. 1b, or not fluid-connected if there is an overlap of the flow cross-sections in the transition areas 2ab, 2bc, but the coolant pressure in the medium-pressure inlet 2 is below the coolant pressure in the outlet chamber 5b and thus the check valve 13 is closed, as shown in Fig. 1c, as well as if there is no overlap in at least one transition area 2ab, 2bc between first section 2a and second section 2b and between second section 2b and third section 2c, as shown in Fig. 1d.

[0035] The overlap of the flow cross-sections in the first transition region 2ab of the first section 2a and the second section 2d is designed such that the fluid connection between the medium-pressure inlet 2 and the outlet chamber 5b is already provided at low compression in the outlet chamber 5b, as shown in Fig. 1a, so that coolant with a slight pressure increase compared to the low pressure can flow into the outlet chamber 5b before the check valve 13 interrupts the fluid connection again due to the increasing compression in the outlet chamber 5b, as shown in Fig. 1c.

[0036] A second embodiment of a oscillating piston compressor 1 according to the invention, with a medium-pressure inlet 2, is shown here by way of example. The accompanying figures show: Fig. 2a, Fig. 2b, Fig. 2c and Fig. 2d: each a schematic representation of the oscillating piston compressor 1 with medium pressure inlet 2 at different positions of an oscillating piston 3.

[0037] In this version, shown in Fig. 2a - Fig. 2d, the oscillating piston compressor 1 with medium-pressure inlet 2, which is advantageous according to the invention, has an alternative embodiment of the second section 2b of the medium-pressure inlet channel. The overlap of the flow cross-sections in the first transition region 2ab of the first section 2a and the second section 2d is designed such that the fluid connection between the medium-pressure inlet 2 and the outlet chamber 5b is only established at advanced compression in the outlet chamber 5b, as shown in Fig. 2b, so that coolant with a high pressure increase compared to the low pressure can flow into the outlet chamber 5b before the check valve 13 interrupts the fluid connection again due to the increasing compression in the outlet chamber 5b, as shown in Fig. 2c. List of reference symbols used 1 vibrating piston compressor 2 Medium pressure inlet 2a first section 2b second section 2c third section 3 oscillating pistons 4 cases 5 cylinders 5a Entrance Room 5b Outlet room 6 eccentrics 7 Drive shaft 8 separating slides 9 Swing bushing 10 Separating slide guide 11 Low-pressure inlet 12 High-pressure outlet 13 Check valve

Claims

[1] Oscillating piston compressor (1) with medium pressure inlet (2), comprising in a housing (4) a cylinder (5) with a oscillating piston (3), wherein the oscillating piston (3) is rotatably mounted on an eccentric (6) of a drive shaft (7) and comprises a separating slide (8) rigidly connected to the oscillating piston (3), a pivot bushing (9) rotatably mounted in the housing (4) for linear guidance of the separating slide (8) in a separating slide guide (10), a low-pressure inlet (11) which is operatively connected to an inlet chamber (5a) in the cylinder (5), a medium pressure inlet (2) which is operatively connected to an outlet chamber (5b) in the cylinder (5), wherein the medium pressure inlet (2) comprises a first section (2a) with a check valve (13) in the housing (4), a second section (2b) in the oscillating bushing (9) and a third section (2c) in the separating slide (8), and a high-pressure outlet (12) which is operatively connected to the outlet chamber (5b) in the cylinder (5). [2] Oscillating piston compressor (1) with medium pressure inlet (2) according to claim 1, characterized by , that depending on the angular position of the oscillating piston (3) in the cylinder (5) and the angular position of the oscillating bushing (9) relative to the housing (4), the mean pressure inlet (2) is fluidly connected or not fluidly connected to the outlet chamber (5b) in the cylinder (5). [3] Oscillating piston compressor (1) with intermediate pressure inlet (2) according to one of the preceding claims, characterized by , that the flow cross-section of the second section (2b) decreases in the direction of flow of the incoming coolant.

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