Refrigerant compressor

Abstract

A refrigerant compressor (1) has: a hermetically sealed compressor housing (2); -an electric drive unit (3) comprising a rotor (4) rotatable about an axis of rotation (14), a stator (5) and a crankshaft (6) connected to the rotor in a torque-proof manner; a lubricant container (10) for conveying a lubricant (11), the crankshaft (6) being partially arranged in a sleeve-like portion (21) of the compressor body (20), an intermediate space (25) being formed between the second stator portion (17) and the compressor body as viewed in the radial direction (24); when viewed in the radial direction, a gap (26) is formed between the second stator part arranged in the intermediate space and the compressor body, into which gap the lubricant is fed in the operating state. According to the invention, the rotor ring (38) in the second rotor part comprises a lubricant distribution device which breaks the rotational symmetry of the rotor ring with respect to the axis of rotation.

Description

Technical Field

[0001] The present invention relates to a refrigerant compressor, comprising:

[0002] - Hermetically sealed compressor housing;

[0003] an electric drive unit arranged inside the compressor housing, the electric drive unit comprising a rotor rotatable about an axis of rotation, a stator and a crankshaft, the rotor being connected to the rotor in a torque-proof manner;

[0004] a piston-cylinder unit arranged inside the housing, the piston-cylinder unit comprising a piston which is movably arranged in a cylinder of the piston-cylinder unit and which can be driven by the crankshaft to compress the refrigerant;

[0005] A lubricant container, which, when the refrigerant compressor is in operation, serves to vertically convey lubricant via the crankshaft from a lubricant sump arranged in the bottom region of the compressor housing.

[0006] wherein, viewed in a first direction, the stator extends from a first stator part to a second stator part, and the rotor extends from a first rotor part to a second rotor part, wherein the first direction is parallel to the axis of rotation and points from the bottom region towards the piston-cylinder unit;

[0007] wherein the crankshaft is partially disposed in a sleeve-shaped portion of the compressor block,

[0008] wherein, viewed in a radial direction orthogonal to the first direction and pointing away from the axis of rotation, an intermediate space is formed between the second stator part and the compressor body, and the second rotor part is at least partially arranged in the intermediate space,

[0009] A gap is formed between the second rotor part and the compressor body when viewed in a radial direction, and lubricant is delivered into the gap when the refrigerant compressor is in operation, wherein the rotor includes a rotor ring arranged in the second rotor part. Background Art

[0010] Refrigerant compressors are known that take the form of reciprocating compressors. These refrigerant compressors have a hermetically sealed compressor housing and an electric drive unit disposed within the compressor housing. The electric drive unit comprises a rotor rotatable about an axis of rotation, a stator, and a crankshaft, which is torque-resistantly connected to the rotor. The electric drive unit is hereinafter referred to as an electric motor. A piston-cylinder unit is disposed within the housing. The piston is movably disposed within a cylinder of the unit and can be driven by the crankshaft to compress the refrigerant and circulate it through the refrigeration system.

[0011] Due to unavoidable losses, the electric motor heats up during operation of the refrigerant compressor. Therefore, the goal is to ensure that the temperature of the electric motor does not exceed a critical level under all operating conditions of the compressor. One way to address this problem is to design the electric motor to be sufficiently large, especially to have a relatively large stator height. The stator typically has a stator lamination and a stator winding with upper and lower coils.

[0012] To avoid increasing the size of the electric motor, the lubricant required for lubricating the crankshaft, pistons, and connecting parts (the so-called crank mechanism) can be used to at least partially cool the electric motor. Specifically, the lower coils of the stator can be immersed in lubricant and oil, respectively, wherein the oil simultaneously cools the lower coils of the stator.

[0013] However, the upper coils, which are usually covered by the compressor block, are usually not cooled. Therefore, there is a risk of the stator overheating under certain circumstances.

[0014] To also cool the upper stator coils, EP 4 092 271 A1 discloses providing at least one channel in the rotor, through which lubricant is conveyed, together with helical grooves in the crankshaft, to the upper rotor section, which is formed by the rotor ring. Centrifugal force sprays the lubricant from the rotor ring onto the upper stator coils, where it absorbs heat and thereby reduces the stator temperature. However, the lubricant flow to the upper stator coils is limited, which in turn limits the cooling of these coils. Furthermore, this solution has the disadvantage that the required changes to the rotor design are technically complex and expensive. Summary of the Invention

[0015] Purpose of the Invention

[0016] The object of the present invention is therefore to provide a refrigerant compressor that avoids the above-mentioned disadvantages. In particular, the refrigerant compressor according to the present invention should be able to achieve a compact design while being able to efficiently cool the electric motor, in particular the upper winding of the stator, and the cooling effect should be improved compared to known solutions.

[0017] Preferably, cooling should be achieved in a structurally simple manner. SUMMARY OF THE INVENTION

[0019] In order to solve the above problems, a refrigerant compressor is provided, which has:

[0020] - Hermetically sealed compressor housing;

[0021] an electric drive unit arranged inside the compressor housing, the electric drive unit comprising a stator, a crankshaft, and a rotor rotatable about an axis of rotation, the crankshaft being connected to the rotor in a torque-proof manner;

[0022] a piston-cylinder unit arranged inside the housing, the piston-cylinder unit comprising a piston which is movably arranged in a cylinder of the piston-cylinder unit and which can be driven by the crankshaft to compress the refrigerant;

[0023] a lubricant container for vertically conveying lubricant from a lubricant tank provided in the bottom region of the compressor housing via the crankshaft when the refrigerant compressor is in operation;

[0024] wherein, viewed in a first direction, the stator extends from a first stator part to a second stator part, and the rotor extends from a first rotor part to a second rotor part, wherein the first direction is parallel to the axis of rotation and points from the bottom region towards the piston-cylinder unit,

[0025] wherein the crankshaft is partially arranged in a sleeve-shaped portion of the compressor block;

[0026] wherein, viewed in a radial direction orthogonal to the first direction and pointing away from the axis of rotation, an intermediate space is formed between the second stator part and the compressor body, and the second rotor part is at least partially arranged in the intermediate space;

[0027] In which, when viewed in the radial direction, a gap is formed between the second rotor part and the compressor body, and lubricant is delivered to the gap when the refrigerant compressor is in operation; in which, the rotor includes a rotor ring arranged in the second rotor part, and according to the present invention, the rotor ring includes a lubricant distribution device, which breaks the rotational symmetry of the rotor ring relative to the axis of rotation so as to improve the flow of lubricant from the gap to the second stator part when the refrigerant compressor is in operation.

[0028] As described above, the refrigerant may flow through a refrigeration system, such as a refrigerator, through a refrigerant compressor in operation.

[0029] Such lubricant containers are known. The lubricant container may be arranged on the crankshaft and may be connected to the crankshaft or integrated into the crankshaft such that the lubricant container rotates together with the crankshaft during operation of the refrigerant compressor.

[0030] Typically, the lubricant reservoir has a sleeve-like portion, the end portion of which protrudes into a lubricant trough provided within the housing. Lubricant entering the lubricant reservoir through the lubricant trough's inlet opening is forced into a parabolic shape against the reservoir's inner wall due to the rotation of the lubricant reservoir—induced by the rotation of the crankshaft—and the corresponding centrifugal force. Consequently, the lubricant moves along the inner wall of the lubricant reservoir and along the inner wall of the crankshaft, which is hollow or provided with internal channels or bores that are fluidically connected to the lubricant reservoir. Furthermore, the crankshaft may have additional conveying or guiding means for the lubricant on its lateral surface areas or surfaces, such as one or more grooves, preferably extending helically or spirally along the longitudinal axis of the crankshaft, which generally coincides with the axis of rotation. The conveying / guiding means is fluidically connected to the hollow interior or bore of the crankshaft, for example, via at least one connecting hole through which the lubricant can flow.

[0031] Thus, when the refrigerant compressor is in operation, lubricant is conveyed vertically via the crankshaft through the lubricant container, wherein the lubricant is conveyed at least partially inside the crankshaft and / or in lateral surface areas or surfaces of the crankshaft.

[0032] The stator generally comprises a first stator winding arranged in a first stator portion. Typically, when the refrigerant compressor is in operation, the first stator portion is arranged below the second stator portion, so in this case the first stator winding can be referred to as a lower stator winding.

[0033] Similarly, the stator may include a second stator winding disposed in a second stator portion that is typically disposed above the first stator portion when the refrigerant compressor is in operation. Thus, in this case, the second stator winding may be referred to as an upper stator winding.

[0034] Typically, the stator further comprises stator laminations extending between the first stator portion and the second stator portion.

[0035] The rotor may include a first rotor ring located in a first rotor portion, wherein the first rotor portion may also consist of the first rotor ring. Furthermore, the rotor may include a second rotor ring located in a second rotor portion, referred to hereinabove as the "rotor ring," wherein the second rotor portion may also consist of the second rotor ring. Typically, when the refrigerant compressor is in operation, the first rotor portion is arranged below the second rotor portion, and in this case, the first rotor ring may be referred to as the lower rotor ring, and the second rotor ring may be referred to as the upper rotor ring.

[0036] Typically, the rotor also includes rotor laminations extending between the first and second rotor sections. Typically, the primary function of the rotor rings—or the first and second rotor rings—is to hold the rotor laminations, and preferably, the rotor disks together. The rotor laminations can be made from electrical steel sheets. The rotor rings—or the first and second rotor rings—can be made from aluminum or an aluminum alloy.

[0037] The rotor ring, or the second rotor ring, has an inner surface facing the crankshaft. The inner surface defines a gap, in particular in the radial direction.

[0038] The crankshaft is arranged in sections in a sleeve-like portion of the compressor block, and the compressor block preferably also provides support for the crankshaft.

[0039] Mathematically, there are an infinite number of radial directions. Therefore, "radial directions" and "a radial direction" refer to all of these possible directions, unless expressly specified otherwise.

[0040] The second rotor part, in particular the rotor ring or the second rotor ring, can be arranged in sections or as a whole in the intermediate space.

[0041] Preferably, the gap between the second rotor part and the compressor block has a directional component parallel to the first direction and is open towards the intermediate space.

[0042] When the refrigerant compressor is in operation, the lubricant is conveyed into the gap and further conveyed or distributed to the second stator part through the intermediate space to cool the second stator part, in particular the second stator winding in the second stator part, wherein the lubricant can leave the gap and move toward the second stator part under the action of centrifugation.

[0043] Typically, the inner surface of the rotor ring or the second rotor ring, and more generally, the inner surface of the entire rotor ring, is almost completely rotationally symmetrical with respect to the axis of rotation. This rotational symmetry generally helps avoid any unbalanced masses that could negatively impact the rotational behavior of the rotor, thereby affecting the performance of the electric motor and refrigerant compressor, respectively. Furthermore, such unbalanced masses could affect the robustness of the compressor, as the higher vibration levels caused by an unbalanced rotor could potentially lead to failure of the suspension springs.

[0044] However, it was surprisingly found that breaking the rotational symmetry of the lubricant distribution device can significantly improve the flow and delivery of lubricant to the second stator part. Unbalanced masses that could negatively impact the performance and / or robustness of the refrigerant compressor can still be avoided quite easily, for example, by arranging the lubricant distribution device around the rotation axis so as to achieve n-fold symmetry, where n is an integer greater than 1, and / or by providing at least one balancing weight.

[0045] In a preferred embodiment of the refrigerant compressor according to the invention, the lubricant distribution device comprises an opening in the rotor ring, which fluidically connects the gap with the intermediate space, wherein the opening extends with a directional component parallel to the radial direction. The portion of the rotor ring formed by the opening does not restrict the gap and contributes to a lubricant flow that causes the lubricant to flow into the intermediate space and toward the second stator part.

[0046] Advantageously, the opening can be easy to manufacture, for example by drilling or milling, in particular keyway machining. Therefore, in a particularly preferred embodiment of the refrigerant compressor according to the invention, the opening comprises a distribution through-hole bounded by the rotor ring in a first direction and / or a distribution slot having an open end when viewed in the first direction. For example, the distribution through-hole can be drilled and / or the distribution slot can be milled. The distribution through-hole allows a very precise definition of the direction in which the lubricant is to be delivered. When the refrigerant compressor is in operation, the distribution slot allows a particularly large amount of lubricant to be delivered from the gap into the intermediate space and towards the second stator part within a certain amount of time.

[0047] Additionally or alternatively, in a preferred embodiment of the refrigerant compressor according to the present invention, the lubricant distribution device includes spray vanes arranged on a top surface of the rotor ring, the top surface facing in the first direction. The spray vanes allow for particularly precise control of the direction in which the lubricant exits the gap under centrifugal action. This ensures that a significant proportion of the lubricant exiting the gap under centrifugal action reaches the second stator portion directly, thereby improving cooling efficiency.

[0048] Additionally or alternatively, in a preferred embodiment of the refrigerant compressor according to the present invention, the rotor ring has an inner surface facing the crankshaft, and the lubricant distribution device includes at least one pocket formed by the inner surface, which breaks the rotational symmetry of the inner surface relative to the axis of rotation. The at least one pocket increases the volume available for lubricant in the gap. Therefore, when the refrigerant compressor is in operation, more lubricant can be delivered to the gap, which promotes the formation of a lubricant flow, thereby improving the flow and delivery of lubricant out of the gap toward the second stator part. Furthermore, cooling of the second stator part by the lubricant is also improved.

[0049] In a preferred embodiment of the refrigerant compressor according to the present invention, at least one through hole for lubricant is provided on the compressor body between the crankshaft and the gap. In order to avoid the high technical costs and the high cost of providing a channel for conveying lubricant to the gap in the rotor design, at least one through hole is provided on the compressor body. In the operating state of the refrigerant compressor, the at least one through hole allows lubricant to flow from the side of the crankshaft - inside the sleeve-shaped part of the compressor body - into the gap, from where the lubricant can be distributed to the second stator part to cool the second stator part. The one or more through holes can be easily made as drilled holes without having to change the rotor design (at least one channel is provided on the rotor for conveying lubricant to the upper part of the rotor and the rotor ring, respectively).

[0050] In a particularly preferred embodiment of the refrigerant compressor according to the invention, an accumulation volume for accumulating lubricant is provided between a lateral surface of the crankshaft and the inner wall of the sleeve-shaped portion of the compressor block, wherein the accumulation volume is fluidically connected to the at least one through-opening. In the operating state of the refrigerant compressor, the accumulation volume provides a lubricant reservoir, thereby improving the flow of lubricant or oil through the at least one through-opening into the gap and further to the second stator part.

[0051] Although it is conceivable that the at least one through-hole is fluidically connected to the accumulation volume by means of a connecting device, such as a connecting channel, in a particularly preferred embodiment of the refrigerant compressor according to the invention, the accumulation volume is arranged in the region of the at least one through-hole, as viewed along the axis of rotation, and the at least one through-hole fluidically connects the accumulation volume to the gap. The latter means that there is a direct fluid connection between the at least one through-hole and the accumulation volume without any connecting device in between. This ensures that the lubricant can be delivered particularly effectively into the gap and therefore further to the second stator part. More generally, in a particularly preferred embodiment of the refrigerant compressor according to the invention, the at least one through-hole fluidically connects the accumulation volume to the gap.

[0052] As described above, the lubricant can be conveyed or guided through the crankshaft via a channel or hollow interior of the crankshaft (via at least one connecting hole) in cooperation with at least one groove provided on the lateral surface of the crankshaft. Therefore, in an embodiment comprising an accumulation volume, the lubricant can be conveyed from the lubricant container into the accumulation volume. Therefore, in more general terms, in a particularly preferred embodiment of the refrigerant compressor according to the present invention, the crankshaft includes a conveying device for conveying the lubricant from the lubricant container to the accumulation volume when the refrigerant compressor is in operation. The conveying or guiding device can be integrally formed with the crankshaft or as a separate element.

[0053] In order to provide a design that is particularly easy to manufacture, in a particularly preferred embodiment of the refrigerant compressor according to the present invention, the crankshaft includes: an internal channel for vertically conveying lubricant in the crankshaft when the refrigerant compressor is in operation; a connecting hole fluidly connecting the internal channel with the lateral surface of the crankshaft; and a helical groove arranged on the lateral surface and for additionally conveying lubricant vertically, wherein, viewed in a first direction, the helical groove extends from a first surface portion via an intermediate surface portion to a second surface portion on the lateral surface of the crankshaft, wherein the first surface portion, the intermediate surface portion and the second surface portion are arranged in a sleeve-like portion of the compressor body, wherein an accumulation volume for accumulating lubricant is only arranged in the intermediate surface portion, or between the intermediate surface portion and the inner wall of the sleeve-like portion of the compressor body and between the second surface portion and the inner wall of the sleeve-like portion of the compressor body.

[0054] Of course, it is conceivable to provide a plurality of internal channels and / or a plurality of connecting holes and / or a plurality of helical grooves, for example for fine-tuning the amount of lubricant delivered.

[0055] The internal passages may be made as drilled holes.

[0056] The internal channel may extend parallel to the longitudinal axis or the rotational axis, respectively, of the crankshaft, or may be inclined relative to said axis.

[0057] The helical grooves result in improved transport of lubricant across the lateral surface of the crankshaft, in particular during operation of the refrigerant compressor.

[0058] In the first direction, the accumulation volume can be bounded by the first surface portion on the one hand and by the second surface portion or by a portion of the crankshaft following the second surface portion on the other hand. For example, the portion of the crankshaft following the second surface portion can be formed by a crank pin.

[0059] In order to make the accumulation volume particularly easy to manufacture, in a particularly preferred embodiment of the refrigerant compressor according to the invention, the maximum diameter of the crankshaft within the extension of the accumulation volume is smaller than the maximum diameter in at least one adjacent region, and / or the minimum inner diameter of the sleeve-shaped portion of the compressor block within the extension of the accumulation volume is larger than the minimum inner diameter in at least one adjacent region. The inner diameter of the sleeve-shaped portion is measured over a (net) cross section of the sleeve-shaped portion of the compressor block, wherein the cross section is bounded by the inner wall of the sleeve-shaped portion of the compressor block.

[0060] The accumulation volume can thus be easily formed in the form of a clear cross-section between the portion of the crankshaft arranged within the sleeve-shaped portion of the compressor block and the inner wall of the sleeve-shaped portion of the compressor block. Thus, in the radial direction, the accumulation volume is delimited by the crankshaft and its lateral surface, and by the inner wall of the sleeve-shaped portion of the compressor block, respectively.

[0061] In a particularly preferred embodiment of the refrigerant compressor according to the invention, the maximum diameter of the crankshaft in the region of the intermediate surface portion is smaller than the maximum diameter in the region of the first surface portion, and preferably, the maximum diameter of the crankshaft in the region of the intermediate surface portion is smaller than the maximum diameter in the region of the second surface portion. In this way, the accumulation volume can be defined particularly precisely.

[0062] In order to promote the targeted distribution of lubricant from the gap toward the second stator part by centrifugal force when the refrigerant compressor is in operation, in a preferred embodiment of the refrigerant compressor according to the invention, the distance between the axis of rotation and the inner surface of the rotor ring measured in the radial direction increases, preferably continuously, along a first direction, wherein the inner surface faces the crankshaft. As described above, the inner surface limits the gap, particularly in the radial direction.

[0063] This means that, viewed in the first direction, the gap widens toward the intermediate space. This, in turn, has the following effect: when the refrigerant compressor is in operation, the lubricant leaves the gap under centrifugal force with a significant—rather than a negligible or insignificant—component parallel to the radial direction. Consequently, the lubricant can be better centrifugally directed out of the gap toward the second stator portion, where it can provide cooling.

[0064] To further optimize the centrifugal force generated by the rotation of the rotor, particularly the rotor ring, to transport lubricant to the second stator portion during operation of the refrigerant compressor, in a particularly preferred embodiment of the refrigerant compressor according to the present invention, the inner surface of the rotor ring has an inclined and / or curved shape. This shape can facilitate the lubricant to escape from the gap and continuously flow to the second stator portion during operation of the refrigerant compressor.

[0065] Accordingly, in a preferred embodiment of the refrigerant compressor according to the invention, the stator comprises a second stator winding arranged in the second stator part, and preferably comprises a first stator winding arranged in the first stator part. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The present invention will be described in more detail with reference to the following drawings and in conjunction with preferred embodiments:

[0067] Figure 1 : shows a cross-sectional view of a refrigerant compressor;

[0068] Figure 2 : Shows Figure 1 An enlarged view of detail II in ;

[0069] Figure 3 : Shows Figure 1 A perspective view of a crankshaft of a refrigerant compressor;

[0070] Figure 4 : Figure 3 Cross-section of the crankshaft;

[0071] Figure 5 : A perspective view showing a rotor of a first embodiment of a refrigerant compressor according to the present invention;

[0072] Figure 6 : shows a detail of a cross-sectional view of a first embodiment of a refrigerant compressor according to the present invention;

[0073] Figure 7 : A perspective view showing a rotor of a second embodiment of a refrigerant compressor according to the present invention;

[0074] Figure 8 : shows a detail of a cross-sectional view of a second embodiment of a refrigerant compressor according to the present invention;

[0075] Figure 9 : A perspective view showing a rotor of a third embodiment of a refrigerant compressor according to the present invention;

[0076] Figure 10 : shows a detail of a cross-sectional view of a third embodiment of a refrigerant compressor according to the present invention;

[0077] Figure 11 : A perspective view showing a rotor of a fourth embodiment of a refrigerant compressor according to the present invention;

[0078] Figure 12 : shows a detail of a cross-sectional view of a fourth embodiment of a refrigerant compressor according to the present invention;

[0079] Figure 13 : A perspective view showing a rotor of a fifth embodiment of a refrigerant compressor according to the present invention;

[0080] Figure 14 : shows details of a cross-sectional view of a fifth embodiment of a refrigerant compressor according to the present invention. DETAILED DESCRIPTION

[0081] Figure 1A cross-section of a refrigerant compressor 1 is shown. The refrigerant compressor 1 has a hermetically encapsulated compressor housing 2, sometimes also referred to as an outer shell, and comprises a sealed upper and lower part. Arranged within the housing of the compressor housing 2 is an electric drive unit 3, also referred to as an electric motor. The electric drive unit 3 comprises a stator 5, a crankshaft 6, and a rotor 4 rotatable about an axis of rotation 14, wherein the crankshaft 6 is connected to the rotor 4 in a torque-proof manner.

[0082] Furthermore, a piston-cylinder unit 7 is arranged inside the compressor housing 2 , and the piston-cylinder unit 7 includes a piston 9 , wherein the piston 9 is movably arranged in a cylinder 8 of the piston-cylinder unit 7 and can be driven by the crankshaft 6 to compress the refrigerant.

[0083] Furthermore, the refrigerant compressor 1 comprises a lubricant container 10 which, when the refrigerant compressor 1 is in operation, serves to vertically draw in and deliver lubricant 11 or lubricating oil from a lubricant groove 13 arranged in a bottom region 12 of the compressor housing 2 via the crankshaft 6 . Figure 1 , the lubricant level in the lubricant groove 13 is indicated by a solid horizontal line. The lubricant container 10 is connected to the crankshaft 6 in a torque-proof manner and protrudes into the lubricant groove 13 so that the lubricant 11 can enter the lubricant container 10.

[0084] When the lubricant container 10 rotates with the crankshaft 6 during operation of the refrigerant compressor 1, the lubricant container 10 operates in a known manner by utilizing the centrifugal force acting on the lubricant 11. The lubricant 11 that enters the lubricant container 10 from the lubricant groove 13 through the inlet opening (not shown) is forced into a parabolic shape at the inner wall (not shown) of the lubricant container 10 due to the rotation of the lubricant container 10 and the corresponding centrifugal force. As a result, the lubricant 11 moves along the inner wall of the lubricant container 10 and along the inner wall of the crankshaft 6, which is provided with an internal channel 28, see FIG. Figure 4 , which is fluidically connected to the lubricant container 10. Furthermore, the crankshaft 6 has, on its lateral surface 30, a conveying or guiding device for the lubricant 11 in the form of a helical groove 31 extending helically when viewed along the longitudinal axis of the crankshaft 6, which coincides with the axis of rotation 14. The helical groove 31 is fluidically connected to the internal channel 28 via a connecting hole 29, through which the lubricant 11 can flow.

[0085] Viewed along a first direction 15, the stator 5 extends from a first stator part 16 to a second stator part 17, and the rotor 4 extends from a first rotor part 22 to a second rotor part 23, wherein the first direction 15 is parallel to the axis of rotation 14 and points from the bottom region 12 towards the piston-cylinder unit 7. Typically, when the refrigerant compressor 1 is in operation, the first direction 15 is substantially antiparallel to the direction of gravity.

[0086] In the embodiment of the refrigerant compressor 1 shown, the stator 5 comprises a second stator winding 19 arranged in the second stator part 17 and a first stator winding 18 arranged in the first stator part 16. The first stator winding 18 is partially immersed in the lubricant 11 in the lubricant tank 13 and is thereby cooled by the lubricant 11.

[0087] The crankshaft 6 is partially arranged in a sleeve-shaped portion 21 of the compressor block 20 .

[0088] As viewed in a radial direction 24 perpendicular to the first direction 15 and pointing away from the rotation axis 14, a space 25 is formed between the second stator portion 17 and the compressor body 20. The second rotor portion 23 is disposed in this space 25. As viewed in the radial direction 24, a gap 26 is formed between the second rotor portion 23 and the compressor body 20. During operation of the refrigerant compressor 1, the lubricant 11 is conveyed into the gap 26 and, from there, into the space 25, flowing toward the second stator portion 17 and the second stator winding 19. Consequently, the second stator portion 17 and the second stator winding 19 can be cooled by the lubricant 11.

[0089] In the embodiment of the refrigerant compressor 1 shown, the rotor 4 has a first rotor ring 37 forming the first rotor portion 22 and a second rotor ring 38 forming the second rotor portion 23. The main function of the rotor rings 37, 38 is to hold the laminations of the rotor 4, preferably to hold the laminations of the rotor 4 together. The rotor laminations are made of electrical steel sheets, while the rotor rings 37, 38 are made of aluminum or an aluminum alloy.

[0090] The second rotor ring 38 has an inner surface 39 facing the crankshaft 6 and defining the gap 26 , in particular in the radial direction 24 .

[0091] It has surprisingly been found that a lubricant distribution device, which breaks the rotational symmetry of the second rotor ring 38, in particular of its inner surface 39, relative to the rotation axis 14, can significantly improve the flow and transport of the lubricant 11 toward the second stator part 17. Therefore, in the refrigerant compressor 1 according to the invention, the second rotor ring 38 includes a lubricant distribution device, which breaks the rotational symmetry of the second rotor ring 38 relative to the rotation axis 14, so as to improve the flow of the lubricant 11 from the gap 26 to the second stator part 17 in the operating state of the refrigerant compressor 1.

[0092] Such a lubricant distribution device may comprise openings, respectively on the second rotor ring 38 and on its inner surface 39 , which fluidically connect the gap 26 with the intermediate space 25 , wherein the openings extend with a directional component parallel to the radial direction 24 .

[0093] As an example, Figure 5 The rotor 4 of a first embodiment of a refrigerant compressor 1 is shown, in which the openings are formed as distribution through-holes 40, which are defined by the second rotor ring 38 in the first direction 15. The distribution through-holes 40 can be easily produced by drilling and can very accurately define the direction in which the lubricant 11 is to be delivered.

[0094] In the first embodiment shown, the distribution through-opening 40 extends in the radial direction 24 , see Figure 6 .

[0095] In the illustrated embodiment of the refrigerant compressor 1, a through-hole 27 for the lubricant 11 is provided in the compressor body 20 between the crankshaft 6 and the gap 26. When the refrigerant compressor 1 is in operation, the through-hole 27 allows the lubricant 11 to flow from one side of the crankshaft 6—inside the sleeve-shaped portion 21 of the compressor body 20—into the gap 26. The lubricant 11 can thereby be distributed to the second stator portion 17, cooling the second stator portion 17 and the second stator winding 19, respectively. The through-hole 27 is manufactured by drilling, which is simple and cost-effective to manufacture.

[0096] Although the combination of a lubricant distribution device that breaks the rotational symmetry and one or more through-holes 27 shown works particularly well, it must be emphasized that it is also conceivable to combine a lubricant distribution device that breaks the rotational symmetry with other solutions for delivering the lubricant 11 into the gap 26, such as: arranging at least one channel or groove in the rotor for delivering the lubricant 11 into the gap 26.

[0097] In the illustrated first embodiment of the refrigerant compressor 1 , the distribution through-opening 40 is arranged substantially at the same position as the through-opening 27 , as viewed along the axis of rotation 14 . Figure 6This arrangement improves the flow and through-put of the lubricant 11 from the gap 26 to the second stator portion 17 and the second stator winding 19, respectively.

[0098] As another example, Figure 7 The rotor 4 of a second embodiment of a refrigerant compressor 1 is shown, wherein the opening is formed as a distribution slot 41 having an open end when viewed from the first direction 15. The distribution slot 41 can be easily produced by milling and, when the refrigerant compressor 1 is in operation, allows a large amount of lubricant 11 to be conveyed from the gap 26 into the intermediate space 25 over a certain period of time, to flow to the second stator part 17 and the second stator winding 19, respectively. In the second embodiment shown, the extension of the distribution slot 41 along the axis of rotation 14 begins essentially at the same point as the extension of the through-hole 27, see Figure 8 , which further improves the flow and throughput of the lubricant 11 from the gap 26 to the second stator portion 17 and the second stator winding 19 , respectively.

[0099] Figure 9 A perspective view of a rotor 4 of a third embodiment of a refrigerant compressor 1 is shown, wherein the lubricant distribution device that breaks the rotational symmetry is arranged on the top surface 43 of the second rotor ring 38 (see FIG. Figure 2 ) is formed with a spray blade 42 on the stator portion 17, the top surface 43 of which faces the first direction 15. The spray blade 42 allows for particularly precise adjustment of the spray direction of the lubricant 11 when it leaves the gap 26 under the centrifugal effect. Therefore, when the refrigerant compressor 1 is in operation, it can be ensured that a large part of the lubricant 11 that leaves the gap 26 under the centrifugal effect directly reaches the second stator portion 17, thereby improving the cooling efficiency. In addition, as Figure 10 As shown, the spray vanes 42 are arranged closest to the end 45 of the second stator part 17 when viewed in the first direction 15. The spray vanes 42 can thus distribute the lubricant 11 particularly evenly in the region of said end 45, thereby allowing particularly effective cooling of the second stator winding 19 in this region.

[0100] Figure 11 A perspective view of the rotor 4 of a fourth embodiment of the refrigerant compressor 1 is shown, wherein, in order to provide a lubricant distribution device that breaks the rotational symmetry, the inner surface 39 of the second rotor ring 38 is formed with a plurality of pockets 44, thereby breaking the rotational symmetry of the inner surface 39 (and the second rotor ring 38) relative to the rotation axis 14.

[0101] The pocket 44 increases the volume of the lubricant 11 in the gap 26, see Figure 12Therefore, when the refrigerant compressor 1 is in operation, more lubricant 11 can be delivered to the gap 26, which helps to form a lubricant flow, thereby improving the flow and delivery of the lubricant 11 out of the gap 26 toward the second stator part 17. Accordingly, the cooling of the second stator part 17 and the second stator winding 19 by the lubricant 11 is also improved.

[0102] In principle, the volume for the lubricant 11 in the gap 26 can be significantly increased by only one pocket 44. This is illustrated in the fifth embodiment, in which Figure 13 A rotor 4 is shown with a pocket 44, Figure 14 Details of the corresponding cross-sectional views are shown.

[0103] from Figure 2 As can be seen particularly clearly in the enlarged view of detail II, in the illustrated embodiment of the refrigerant compressor 1, an accumulation volume 35 for accumulating the lubricant 11 is provided between the lateral surface 30 of the crankshaft 6 and the inner wall 36 of the sleeve-shaped portion 21 of the compressor block 20, wherein the accumulation volume 35 is fluidically connected to the through-opening 27. The accumulation volume 35 provides a lubricant reservoir in the operating state of the refrigerant compressor 1, thereby improving the flow of the lubricant 11 via the through-opening 27 into the gap 26 and further to the second stator part 17.

[0104] In the embodiment of the refrigerant compressor 1 shown, there is a direct fluid connection between the through-opening 27 and the accumulation volume 35 , so that the through-opening 27 fluidically connects the accumulation volume 35 to the intermediate space 26 .

[0105] As mentioned above, the crankshaft 6 comprises the internal channel 28, the connecting hole 29 and the helical groove 31. These elements constitute a conveying device for conveying the lubricant 11 from the lubricant container 10 to the accumulation volume 35 when the refrigerant compressor 1 is in operation.

[0106] Viewed in the first direction 15 , the helical groove 31 extends on the lateral surface 30 of the crankshaft 6 from a first surface portion 32 via an intermediate surface portion 33 to a second surface portion 34 , see Figure 3 The first surface portion 32 , the intermediate surface portion 33 and the second surface portion 34 are arranged within the sleeve-shaped portion 21 of the compressor body 20 . In the embodiment of the refrigerant compressor 1 shown, the accumulation volume 35 is arranged only between the intermediate surface portion 33 and the inner wall 36 of the sleeve-shaped portion 21 of the compressor body 20 .

[0107] To facilitate the production of the accumulation volume 35, the maximum diameter DC of the crankshaft 6 within the extension of the accumulation volume 35 is smaller than its maximum diameter in adjacent regions. Thus, the maximum diameter DC of the crankshaft 6 in the region of the intermediate surface portion 33 is smaller than its maximum diameter in the region of the first surface portion 32 and smaller than its maximum diameter in the region of the second surface portion 34. For the sake of completeness, it should be noted, in addition or alternatively, that the minimum inner diameter DB of the sleeve-shaped portion 21 of the compressor block 20 within the extension of the accumulation volume 35 may be greater than its maximum diameter in at least one adjacent region.

[0108] like Figure 2 As is particularly clearly shown, in the embodiment of the refrigerant compressor 1 shown, a distance d between the axis of rotation 14 and the inner surface 39 of the second rotor ring 38 measured in the radial direction 24 increases substantially continuously in the first direction 15 .

[0109] Specifically, when viewed along the first direction 15 , the inner surface 39 has a shape that is first inclined and then curved.

[0110] This means that, viewed in the first direction 15, the gap 26 widens toward the intermediate space 25. This in turn has the following effect: when the refrigerant compressor 1 is in its operating state, the lubricant 11 leaves the gap 26 under the centrifugal effect with a considerable—rather than a rather small or negligible—direction component parallel to the radial direction 24. As a result, the lubricant 11 can better exit the gap 26 under the centrifugal effect toward the second stator part 17, where it can provide cooling for the second stator winding 19.

[0111] Reference Signs List

[0112] 1 Refrigerant compressor

[0113] 2 Compressor housing

[0114] 3 Electric drive unit

[0115] 4 rotors

[0116] 5 Stator

[0117] 6 Crankshaft

[0118] 7 Piston-cylinder unit

[0119] 8 cylinders

[0120] 9 Piston

[0121] 10 Lubricant container

[0122] 11 Lubricant

[0123] 12 Bottom area of ​​the compressor housing

[0124] 13 Lubricant tank

[0125] 14 Rotation axis

[0126] 15 First Direction

[0127] 16 First stator part

[0128] 17 Second stator part

[0129] 18 First stator winding

[0130] 19 Second stator winding

[0131] 20 Compressor body

[0132] 21 Sleeve-shaped part of the compressor body

[0133] 22. First rotor section

[0134] 23 Second rotor section

[0135] 24 radial direction

[0136] 25 In-between Space

[0137] 26 Gap

[0138] 27 through holes

[0139] 28 Internal Passage

[0140] 29 connection holes

[0141] 30 Lateral surface of crankshaft

[0142] 31 spiral grooves

[0143] 32 first surface portion

[0144] 33 Middle surface section

[0145] 34 Second surface portion

[0146] 35 Accumulation volume

[0147] 36 inner wall

[0148] 37 First rotor ring

[0149] 38 Second rotor ring

[0150] 39 Inner surface of the second rotor ring

[0151] 40 distribution through holes

[0152] 41 allocation slots

[0153] 42 spray blades

[0154] 43 Top surface of the second rotor ring

[0155] 44 pouch

[0156] 45 End of the second stator portion viewed along the first direction

[0157] DC crankshaft diameter

[0158] DB Inner diameter of the sleeve-shaped part of the compressor body

[0159] d is the distance between the axis of rotation and the inner surface of the second rotor ring.

Claims

1. A refrigerant compressor (1), comprising: - a hermetically sealed compressor housing (2); an electric drive unit (3) arranged inside the housing of the compressor housing (2) and comprising a stator (5), a crankshaft (6) and a rotor (4) rotatable about an axis of rotation (14), the crankshaft (6) being connected to the rotor (4) in a torque-proof manner; a piston-cylinder unit (7) arranged inside the housing and comprising a piston (9) which is movably arranged in a cylinder (8) of the piston-cylinder unit (7) and which can be driven by the crankshaft (6) to compress the refrigerant; a lubricant container (10) for vertically conveying lubricant (11) from a lubricant groove (13) provided in a bottom region (12) of the compressor housing (2) via the crankshaft (6) when the refrigerant compressor (1) is in operation, in, Viewed in a first direction (15), the stator (5) extends from a first stator part (16) to a second stator part (17), and the rotor (4) extends from a first rotor part (22) to a second rotor part (23), wherein the first direction (15) is parallel to the axis of rotation (14) and points from the bottom region (12) towards the piston-cylinder unit (7), wherein the crankshaft (6) is partially arranged in a sleeve-shaped portion (21) of a compressor body (20), wherein, viewed in a radial direction (24) orthogonal to the first direction (15) and pointing away from the rotation axis (14), an intermediate space (25) is formed between the second stator part (17) and the compressor body (20), and the second rotor part (23) is at least partially arranged in the intermediate space (25), wherein, viewed in the radial direction (24), a gap (26) is formed between the second rotor portion (23) and the compressor body (20), and in the operating state of the refrigerant compressor (1), lubricant (11) is delivered to the gap (26), wherein the rotor (4) includes a rotor ring (38) arranged in the second rotor portion (23), characterized in that the rotor ring (38) includes a lubricant distribution device, which breaks the rotational symmetry of the rotor ring (38) relative to the rotation axis (14), thereby improving the fluidity of the lubricant (11) flowing from the gap (26) to the second stator portion (17) in the operating state of the refrigerant compressor (1).

2. The refrigerant compressor (1) according to claim 1, characterized in that The lubricant distribution device comprises openings (40, 41) in the rotor ring (38), which fluidically connect the gap (26) with the intermediate space (25), wherein the openings (40, 41) extend with a directional component parallel to the radial direction (24).

3. The refrigerant compressor (1) according to claim 2, characterized in that The opening comprises a distribution through-hole (40) which is bounded by the rotor ring (38) in the first direction (15) and / or a distribution notch (41), the distribution through-hole (40) having an open end when viewed in the first direction (15).

4. The refrigerant compressor (1) according to any one of claims 1 to 3, characterized in that The lubricant distribution device comprises spray vanes (42) arranged on a top surface (43) of the rotor ring (38), the top surface (43) facing in the first direction (15).

5. The refrigerant compressor (1) according to any one of claims 1 to 4, characterized in that The rotor ring (38) has an inner surface (39) facing the crankshaft (6), and the lubricant distribution device includes at least one pocket (44) formed by the inner surface (39) and breaking the rotational symmetry of the inner surface (39) with respect to the rotation axis (14).

6. The refrigerant compressor (1) according to any one of claims 1 to 5, characterized in that At least one through hole (27) for the lubricant (11) is provided in the compressor block (20) between the crankshaft (6) and the gap (26).

7. The refrigerant compressor (1) according to claim 6, characterized in that An accumulation volume (35) for accumulating lubricant (11) is provided between a lateral surface (30) of the crankshaft (6) and an inner wall (36) of the sleeve-shaped portion (21) of the compressor block (20), wherein the accumulation volume (35) is fluidically connected to the at least one through-hole (27).

8. The refrigerant compressor (1) according to claim 7, characterized in that The at least one through-hole (27) fluidically connects the accumulation volume (35) to the gap (26).

9. The refrigerant compressor (1) according to any one of claims 7 to 8, characterized in that The crankshaft (6) comprises a conveying device (28, 29, 31) for conveying the lubricant (11) from the lubricant container (10) to the accumulation volume (35) when the refrigerant compressor (1) is in operation.

10. The refrigerant compressor (1) according to any one of claims 7 to 9, characterized in that The crankshaft (6) comprises: an internal channel (28) for conveying the lubricant (11) vertically in the crankshaft (6) in the operating state of the refrigerant compressor (1); a connecting hole (29) for fluidically connecting the internal channel (28) with the lateral surface (30) of the crankshaft (6); and a helical groove (31) provided on the lateral surface (30) for additionally conveying the lubricant (11) vertically. wherein, viewed in the first direction (15), the helical groove (31) extends on the lateral surface (30) of the crankshaft (6) from a first surface portion (32) via an intermediate surface portion (33) to a second surface portion (34), wherein the first surface portion (32), the intermediate surface portion (33) and the second surface portion (34) are arranged in the sleeve-shaped portion (21) of the compressor block (20), The accumulation volume (35) for accumulating the lubricant (11) is provided only between the intermediate surface portion (33) and the inner wall (36) of the sleeve-shaped portion (21) of the compressor body (20), or the accumulation volume (35) for accumulating the lubricant (11) is provided between the intermediate surface portion (33) and the second surface portion (34) and the inner wall (36) of the sleeve-shaped portion (21) of the compressor body (20).

11. The refrigerant compressor (1) according to any one of claims 7 to 10, characterized in that The maximum diameter (DC) of the crankshaft (6) within the extension of the accumulation volume (35) is smaller than the maximum diameter in at least one adjacent region, and / or the minimum inner diameter (DB) of the sleeve-shaped portion (21) of the compressor block (20) within the extension of the accumulation volume (35) is larger than the minimum inner diameter in at least one adjacent region.

12. The refrigerant compressor (1) according to any one of claims 7 to 11 and according to claim 10, characterized in that The maximum diameter (DC) of the crankshaft (6) in the region of the intermediate surface portion (33) is smaller than the maximum diameter in the region of the first surface portion (32), and preferably, the maximum diameter (DC) of the crankshaft (6) in the region of the intermediate surface portion (33) is smaller than the maximum diameter in the region of the second surface portion (34).

13. The refrigerant compressor (1) according to any one of claims 1 to 12, characterized in that The distance (d) between the rotation axis (14) and the inner surface (39) of the rotor ring (38) measured in the radial direction (24) increases along the first direction (15), preferably the distance (d) between the rotation axis (14) and the inner surface (39) of the rotor ring (38) measured in the radial direction (24) increases continuously along the first direction (15), wherein the inner surface (39) faces the crankshaft (6).

14. The refrigerant compressor (1) according to claim 13, characterized in that The inner surface (39) of the rotor ring (38) has an inclined and / or curved shape.

15. The refrigerant compressor (1) according to any one of claims 1 to 14, characterized in that The stator (5) comprises a second stator winding (19) arranged in the second stator part (17), and preferably comprises the first stator winding (18) arranged in the first stator part (16).

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