Electric refrigerant drive scroll compressor

Abstract

The invention relates to a scroll compressor (6) of an electric refrigerant drive (2), comprising: a housing (20) having a low-pressure chamber (46) and a high-pressure chamber (48) as well as compressor chambers (S, K, D, DD) and a back-pressure chamber (60); a fixed scroll (44) having a base plate (44) and a spiral wall (44a), wherein the base plate (44b) of the fixed scroll (44) defines the high-pressure chamber (60); and a movable scroll (34) having a base plate (34b) and a spiral wall (34a), wherein the spiral wall is embedded in the spiral wall (44a) of the fixed scroll (44) and forms a compressor chamber (S, K, D, DD) with the spiral wall of the fixed scroll, wherein the base plate (34b) of the movable scroll (34) defines the high-pressure chamber (60). a) defines a back-pressure chamber (60), wherein at least one fluid connection (64, 66) is provided, which connects the back-pressure chamber (60) to one of the compressor chambers (K, D, DD), wherein at least one fluid connection (64, 66) is introduced into an axial abutment surface of a spiral wall (34a) of one of the vortex bodies (34), the abutment surface abutting against a base plate (44b) of each other vortex body (44), and wherein the base plate (44b) of the other vortex body (4) has a certain number of recesses (68, 68'), which are swept at least in sections by at least one fluid connection (64, 66) of the abutment surface during the vortex movement, so that the fluid connection (64, 66) is at least temporarily open to the respective compressor chamber (K, D, DD).

Description

Technical Field

[0001] The present invention belongs to the field of positive displacement machines based on the scroll principle and relates to an electric refrigerant drive, in particular a scroll compressor for a refrigerant extruder (refrigerant compressor) for refrigerant in vehicle air conditioning systems. The invention also relates to an electric refrigerant drive having such a scroll compressor. Background Art

[0002] Motor vehicles are often equipped with air conditioning systems that use a system forming a refrigerant circuit to condition the vehicle interior. Such systems typically have a circuit in which a refrigerant is conducted. The refrigerant, for example, R-134a (1,1,1,2-tetrafluoroethane) or R-744 (carbon dioxide), is heated in an evaporator and compressed using a (refrigerant) compressor or extruder. The refrigerant then releases the absorbed heat via a heat exchanger before being redirected to the evaporator via a throttle element.

[0003] Scroll technology is often used as a refrigerant compressor to compress a refrigerant-oil mixture. The resulting oil-gas mixture is separated, the separated gas being introduced into the air conditioning circuit, while the separated oil can be directed to moving parts within a scroll compressor, which is a suitable electrically driven refrigerant compressor, for lubrication.

[0004] The basic components of a scroll compressor are a stationary or fixed scroll (stator scroll, fixed scroll) and a movable, orbiting scroll (rotor scroll, movable, orbiting scroll). The two scrolls (scroll components) are essentially similar in construction and each has a base plate and a spiral wall (wrap) extending axially from the base plate, which is also referred to as a spiral wall below. In the assembled state, the spiral walls of the two scrolls are nested in each other, and a plurality of compressor chambers are formed between the segmented contacting scroll wall portions.

[0005] As the movable scroll moves along its orbit, the sucked oil-air mixture passes from the low-pressure chamber via the inlet to the radially outer first compressor chamber (suction chamber), and from there via another compressor chamber (extrusion chamber) to the radially innermost compressor chamber (injection chamber, discharge chamber), and from there via the central discharge opening to the discharge chamber or high-pressure chamber. The chamber volume in the compressor chamber gradually decreases from radially outward to radially inward, while the pressure of the increasingly compressed medium increases. Therefore, during the operation of the scroll compressor, the pressure in the compressor chamber increases from radially outward to radially inward.

[0006] During operation of a scroll compressor, the pressure generated in the compressor chamber and the resulting axial force push the movable and stationary scroll bodies apart in the axial direction, so that gaps and leaks can occur between the compressor chambers. In order to avoid this as much as possible, in addition to the oil film formed between the friction surfaces of the two scroll bodies, the orbiting scroll body is pressed against the stationary scroll body when necessary. The corresponding axial force (reaction force) is generated in that a receiving or pressure chamber (back pressure chamber) is provided on the back side of the base plate of the orbiting scroll body, in which a specific pressure is generated.

[0007] The axial force generated by the back-pressure chamber is preferably greater than the sum of the individual axial force components of all compressor chambers. However, a necessary compromise is that the axial force of the back-pressure chamber cannot be set too high, as otherwise friction losses and wear on the spiral wall would increase significantly. Therefore, the back-pressure system plays a decisive role in the performance and efficiency of the scroll compressor.

[0008] If the back-pressure system is unable to build up a sufficiently high pressure in the back-pressure chamber, this will cause the scroll elements to axially separate. This will result in axial gaps and the initiation of radial leakage from the radially inner chamber to the radially outer chamber. This will negatively impact refrigerant compression and make operation at such operating points impossible or inefficient.

[0009] Adaptive adjustment of the back-pressure level can be achieved, for example, by means of flow-regulating components. For this purpose, for example, ball check valves, baffles, or nozzles are provided, with the aid of which the pressure balance between the high-pressure chamber and the back-pressure chamber is controlled and / or regulated. However, these additional components increase the costs and assembly effort in manufacturing the scroll compressor.

[0010] It is known, for example, from DE 10 2012 104 045 A1 that a fluid connection is introduced at a specific location in the base plate of the orbiting vortex body as a medium-pressure channel (through-hole, opening, back-pressure port), which connects at least one of the compressor chambers formed by the vortex body to the back-pressure chamber (back-pressure chamber), so that the refrigerant gas from the compression process between the vortex spirals reaches the back-pressure or medium-pressure chamber directly. Since the medium pressure channel in the movable vortex body is connected to the back-pressure chamber, the movable vortex body will be self-adjusting (automatically) pressed towards the fixed vortex body, thereby providing a certain sealing performance (axial sealing performance). Alternatively, the medium-pressure channel can be arranged in the fixed vortex body and guided around the movable vortex body to the back-pressure or medium-pressure chamber. In this case, the back-pressure chamber is connected to the oil suction channel introduced into the motor shaft and is connected to the high-pressure chamber using a further fluid connection. Due to the connection of the backpressure chamber to the high-pressure side, a relatively high backpressure arises during operation, so that, for example, the heat pumping mode of the positive displacement machine is adversely affected or made impossible.

[0011] DE 10 2016 217 358 A1 describes a scroll compressor in which a back-pressure chamber is coupled to different compressor chambers via one or more fluid connections. The fluid connections are arranged in two extrusion chambers, which are spaced apart from the radially inner compressor chamber. The radial spacing of the fluid connections is different, so that the fluid connections are arranged in extrusion chambers with different pressure levels.

[0012] DE 10 2017 110 913 B3 discloses a backpressure system having a fluid connection between a backpressure chamber and a compressor chamber, and a fluid connection from a high-pressure chamber to the backpressure chamber. The fluid connection from the high-pressure chamber to the backpressure chamber is arranged flow-wise downstream of the oil separator in the high-pressure chamber, so that only coolant, and no oil, is returned to the backpressure chamber. This prevents bearings in the backpressure chamber, such as those for a motor shaft, from being lubricated, thereby disadvantageously reducing their service life.

[0013] Depending on the positioning of the intermediate-pressure channel (back-pressure port), in known scroll compressors, the pressure in the back-pressure chamber increases, for example, to approximately 6 bar up to approximately 9 bar, with a pressure ratio of, for example, 3 bar (low pressure) to 25 bar (high pressure). In known refrigerant scroll compressors for motor vehicle air conditioning systems, the intermediate-pressure channel is positioned at approximately 405° from the beginning of the scroll spiral (spiral wall) of the movable (orbiting) scroll.

[0014] A model calculation of a self-adjusting back-pressure mechanism in a scroll compressor is described in the publication "Computer Modeling of Scroll Compressor with Seif Adjusting Back-Pressure Mechanism," presented at the 1986 International Compressor Engineering Conference (Purdue e-Pubs, Purdue University). Among the experimental results, FIG. 12 of the publication shows the range of relative compressor chamber volumes at which the back-pressure port (at various port diameters) should be open (fluidically connected). This range is between 55% and approximately 100% of the relative chamber volume.

[0015] In "A Scroll Compressor for Air Conditioners," by Tojo et al., Purdue e-Pubs (Purdue University), International Compressor Engineering Conferenz, 1984, substantially the same pv diagram is shown in FIG. 11 , wherein the range of compressor chamber volume for which the back pressure port should be open is between 55% and approximately 95%.

[0016] In the two pV diagrams it can be seen that within the volume range considered, the (relative) pressure drops or increases by a factor of 2 (from 2.0 to 1.0 or from 1.0 to 2.0). The opening starting value of the back pressure port is therefore approximately 100% or approximately 95% of the relative compressor chamber volume.

[0017] In "Computer Modeling of Scroll Compressor with Seif Adjusting Back-Pressure Mechanism" by Tojo et al., Purdue e-Pubs (Purdue University), International Compressor Engineering Conferenz, 1986, Figure 5Figure 12 shows the variation of the relative compressor chamber volume as a function of the rotation angle (roll or axis angle Theta, θ) of the orbiting scroll. The variation curves shown are divided into the suction process, the extrusion process, and the discharge process corresponding to the low-pressure range. When the port opening range with respect to the relative volume in Figure 12 is between 55% and 100% or 95%, the angular range in which the port should be positioned is 0° to 335° (for a 100% open starting volume) or 0° to 300° (for a 95% open starting volume).

[0018] The angular positioning of the back pressure port is discussed in "Dynamics of Compliance Mechanisms in Scroll Compressors, Part I: Axial Compliance" by Nieter et al., Purdue e-Pubs (Purdue University), International Compressor Engineering Conferenz, 1990. Figure 7 and Figure 8 ).from Figure 3 The second to last sentence of the second to last paragraph on page 309 shows that the back-pressure or medium-pressure channel (Back-Pressure-Port) should be positioned within an angle range of 360°.

[0019] DE 10 2017 105 175 B3 discloses a scroll compressor having an orbiting scroll body, in which two fluid connections are introduced, which at least temporarily couple the compressor chamber to the back-pressure chamber. In addition, a third fluid connection is provided from the high-pressure chamber to the back-pressure chamber. The first fluid connection is arranged in the middle section of the vortex spiral, i.e., in the section between the radially inner end of the vortex body and the radially outer starting end of the vortex body, wherein the second fluid connection is arranged in the starting area. This means that the first fluid connection is arranged in the compressor chamber between the high-pressure chamber and the low-pressure chamber, wherein the second fluid connection is arranged in the area of ​​the low-pressure chamber. As a result, the pressure in the back-pressure chamber can be adjusted by balancing with the suction pressure or low pressure. Summary of the Invention

[0020] The object of the present invention is to improve a positive displacement machine based on the screw principle so that the pressure in the back-pressure chamber can be self-regulated in an advantageous manner. In particular, a suitable and variable back-pressure system should enable the pressure in the back-pressure chamber to be adapted as flexibly and effectively as possible to different operating pressures. Leakage between the compressor chambers should also be reduced to the greatest extent possible, and friction losses between the stationary scroll and the orbiting scroll should be avoided or at least kept to a minimum. Furthermore, the object of the present invention is to specify a particularly suitable electric refrigerant drive having such a scroll compressor.

[0021] With regard to the scroll compressor, this object is achieved according to the invention by the features of claim 1, and with regard to the refrigerant drive by the features of claim 10. Advantageous embodiments and developments are the subject matter of the dependent claims. The advantages and embodiments cited with regard to the scroll compressor can also be meaningfully transferred to the refrigerant drive, and vice versa.

[0022] The scroll compressor according to the present invention is intended for, suitable for, and designed for electric refrigerant drives, in particular electric refrigerant compressors. The scroll compressor is particularly designed for conveying and compressing refrigerant in motor vehicle air conditioning systems. The scroll compressor can also be embodied, for example, as an air compressor, wherein the conveyed or compressed fluid is particularly air.

[0023] A scroll compressor has a (compressor) housing with a low-pressure chamber and a high-pressure chamber as well as a compressor chamber (compression chamber) and a back-pressure chamber. In addition, the scroll body has a fixed scroll body and a movable (oscillating) scroll body that moves along an orbit in the driven state (i.e. in operation (compressor mode)), which are preferably at least partially accommodated in the housing. The movable scroll body is also referred to as the orbiting scroll body in the following text. The scroll bodies can also be rotating scroll bodies, so-called co-rotating scrolls (English: Co-Rotating Scrolls), in which both scroll bodies are driven around an eccentric axis. The following statements about the movable and fixed scroll bodies also apply accordingly to the rotating scroll body.

[0024] The scroll bodies or scroll elements each have a base plate (bottom plate) and a spiral wall (scroll spiral) extending essentially perpendicularly thereto, wherein a particularly sickle-shaped compressor chamber is formed between the spiral walls of the two scroll bodies (scroll elements) nested within one another. The spiral walls of the scroll elements, which are preferably essentially symmetrical, each have a spiral angle of approximately 720°, for example. The base plate of the stationary scroll body defines the high-pressure chamber, while the base plate of the movable scroll body defines the back-pressure chamber.

[0025] According to the invention, at least one fluid connection is introduced into the axial contact surface of the spiral wall (spiral tip) of one of the two vortices, which contact surface rests on the base plate of the respective other vortex. The base plate of the other vortex has a certain number of, for example, recessed, or depressions or notches, which are swept or run over at least in sections by at least one fluid connection of the contact surface (spiral tip surface) during the movement along the track, so that the fluid connection is at least temporarily open to the respective compressor chamber. Thus, by introducing the fluid connection into the tip surface of the spiral wall, a timed intervention phase is formed during the operation of the compressor in the manner of a clock valve for the mass flow.

[0026] Once the orbiting scroll body is completely in contact with the stationary scroll body in the axial direction, the fluid connection of the contact surface is usually completely blocked. However, due to the notch or recess or depression in the bottom of the other scroll body, a fluid connection that is time-controlled or time-open is obtained. The resulting pressure change curve is roughly simulated by clock control (Taktung). Therefore, the pressure change curve section of the closed fluid connection is interpolated. From a static point of view, the same pressure as in the case of a continuous fluid connection occurs. However, the advantage of this is that the lost mass flow of the refrigerant is significantly reduced by the back pressure system.

[0027] This advantage can be used, for example, to dimension the hole diameter of at least one fluid connection larger. Since the larger fluid connection is only temporarily open, the mass flow loss is essentially the same as in the case of a permanently open fluid connection with a smaller hole diameter or hole cross section.

[0028] This allows for simpler production with regard to manufacturing tolerances. This is particularly advantageous for refrigerant applications operating in pressure ranges significantly higher than, for example, R134A, and in particular carbon dioxide (CO2, R-774), since at higher pressure levels it is necessary to go deeper into the bore diameter range where manufacturing tolerance fluctuations would have a disproportionately large impact on the back-pressure system.

[0029] For example, when the fluid connections as a whole are only open during half of the compressor cycle, they suitably have twice the cross-sectional area, i.e. a greater cross-sectional area. times the diameter.

[0030] The recesses in the base of the other scroll are arranged in such a way that they allow a fluid connection during orbiting in compressor mode. If the fluid connection is introduced into the spiral wall of the orbiting scroll and the recesses are introduced into the base of the stationary scroll, this means that the recesses are arranged in the vicinity of the circular trajectory of the orbiting fluid connection in the tip or in the contact surface of the orbiting scroll.

[0031] One possible design provides for varying the number of recesses or the temporal length of each recess or depression in order to achieve the best possible configuration. This advantageously reduces the lost mass flow even when the bore diameter or fluid connection diameter is larger.

[0032] Preferably, the recess has a diameter that is greater than or equal to the diameter of the opening of the fluid connection, thereby ensuring that the fluid connection is fully opened or released when the recess is swept over.

[0033] In a suitable improvement, the notch or recess in the bottom of the stationary vortex is sized in such a way that leakage across the spiral wall is not possible. In other words, the diameter of the or each recess is less than or equal to the width of the spiral wall that sweeps over it. Therefore, suitably, the recess has a diameter or width that is greater than the opening diameter of the fluid connection on the one hand and less than the spiral wall width on the other hand. The opening diameter that the fluid connection has is, for example, between 0.1 mm (millimeter) and 1 mm, wherein the recess has a diameter between 0.5 mm and 3 mm, for example 1 mm.

[0034] In a preferred embodiment, at least one fluid connection is arranged on the contact surface of the spiral wall of the movable scroll, wherein the recess is introduced into the base plate of the stationary scroll. In an alternative embodiment, this principle can be implemented in an inverted manner on the stationary scroll. This means that the fluid connection extends through the spiral tip surface of the stationary scroll, while the recess or cutout is arranged in the base plate or base plate of the movable scroll.

[0035] In one advantageous embodiment, the back-pressure chamber is connected to the compressor chambers via at least two fluid connections. Each fluid connection connects a different compressor chamber to the back-pressure chamber. The fluid connections can be direct, i.e., directly connecting the back-pressure chamber to the respective compressor chamber, or at least indirectly. Thus, during operation, the fluid connections function as pressure channels or pressure lines (medium-pressure channels), via which the back-pressure chamber is fluidically connected to the at least two compressor chambers.

[0036] The fluid connection is introduced into the fixed scroll body and / or the movable scroll body. The conjunction "and / or" should be understood here and below as meaning that the features linked by means of this conjunction can be formed both together and as alternatives to each other. In other words, it is possible that the fluid connection is introduced only in the spiral wall of the fixed scroll body, or only in the spiral wall of the movable scroll body, or distributedly, partly in the spiral wall of the fixed scroll body and partly in the spiral wall of the movable scroll body. Accordingly, the recess is arranged in each other scroll body.

[0037] Hereinafter, the compressor chambers are also divided into suction chambers, extrusion chambers, and ejection chambers. For a symmetrical scroll, there is an even number of suction or extrusion chambers. Symmetrical means that the lengths of the two scrolls—the lengths of the spiral walls of the stationary scroll and the orbiting scroll—are essentially the same, meaning that the spiral walls have essentially the same helix angle.

[0038] The suction chamber is open to the low-pressure side (suction side). Once the suction chambers are closed by the orbiting motion of the scroll, they become extrusion chambers, whose sickle-shaped volume is gradually compressed or reduced towards the center of the spiral during the orbiting motion. The two radially innermost extrusion chambers are referred to as ejection chambers. In a process also known as "merging", these ejection chambers are connected or combined to form a common discharge chamber, which transports the compressed refrigerant via the discharge opening into the high-pressure chamber.

[0039] The present invention is additional or another aspect that is provided with, the first fluid connection is communicated with the radially innermost compressor chamber.The radially innermost compressor chamber is the compressor chamber (injection chamber, discharge chamber) that is coupled to the high-pressure chamber via a discharge opening, in particular via a main outlet (main discharge port) during the motion of the movable scroll body along the track. The first fluid connection can be introduced into the compressor chamber itself or its discharge opening at this. In particular, the first fluid connection is arranged in such a way that it cooperates with the discharge chamber via a recessed portion according to the combined angle in the range of an axis angle of 90 ° to 180 °. The second fluid connection is arranged at a spiral angle of 320 ° to 400 ° outwardly offset from the first fluid connection. Thus, a particularly suitable scroll compressor is formed. In particular, a particularly flexible back pressure system is therefore achieved that can achieve the best possible axial force compensation at each operating point or operating state of the scroll compressor.

[0040] By "axial" or "axial direction" is here and hereinafter to be understood in particular a direction parallel (coaxial) to the longitudinal axis of the scroll compressor, i.e. perpendicular to the base plate. Correspondingly, by "radial" or "radial direction" is here and hereinafter to be understood in particular a direction along a radius of the base plate or of the scroll compressor, oriented perpendicularly (transversely) to the longitudinal axis. By "tangential" or "tangential direction" is here and hereinafter to be understood in particular a direction along the circumference of the scroll compressor or of the spiral wall (circumferential direction, azimuthal direction), i.e. perpendicular to the axial and radial directions.

[0041] The backpressure system thus has a combination of fluid connections between the scroll spirals from the backpressure chamber to the compression chamber. Theoretically, the scroll requires at least three fluid connections (one in the middle in the region of the injection or discharge chamber and two in the extrusion chamber for each compression path). However, in symmetrical or nearly symmetrical scrolls, it is possible to reduce the number of fluid connections required in the region of the extrusion and injection chambers to two, since in (substantially) symmetrical scrolls both compression paths perform the same compression.

[0042] The first fluid connection is primarily located in the region of the injection chamber, or rather, the discharge chamber. It is connected to the (radially) innermost compressor chamber, from which the compressed fluid or compressed refrigerant is ejected into the high-pressure chamber via the main discharge port. The subsequent (second) fluid connection is located further along the spiral at a helical angle of 320° to 400°. This fluid connection is therefore located in the region where it establishes a connection with the extrusion chamber.

[0043] During a compression cycle, the two fluid connections operate in different compression ranges. Depending on the high and low pressure levels, a specific back pressure is required to ensure axial force compensation. The refrigerant mass flow (refrigerant mass flow is always also referred to as a certain oil mass flow) is directed to and away from the back-pressure chamber via the two fluid connections. The driving force is the pressure difference between the compressor chamber and the back-pressure chamber. If the pressure in the fluidically connected compressor chamber is lower than the pressure in the back-pressure chamber, refrigerant flows from the back-pressure chamber into the compressor chamber, and vice versa.

[0044] In particular, substantially the entire compression cycle is in active, time-clocked fluid connection with the backpressure chamber.

[0045] In one advantageous embodiment, the cross-sectional areas of the fluid connections, i.e., their flow or fluidic diameters, are weighted because the axial areas of the compressor chambers vary in size. This means that the inner fluid connections always have a smaller diameter than the subsequent outer fluid connections. In other words, the diameters of the fluid connections are adapted to the respective axial areas of the associated compressor chambers.

[0046] A backpressure system with at least two fluid connections enables self-regulation and highly dynamic adaptation of the axial force compensation. Due to the fluid connection to the compressor chamber, the backpressure system makes it possible to adjust the optimal pressure level in the backpressure chamber. The "optimum pressure level" is understood here to be, in particular, the backpressure level at which the compromise between the (axial) contact pressure (which should prevent leakage by minimizing gaps) and friction losses (which lead to power loss and wear) is most favorable. In other words, the "optimum pressure level" exists when the compressor power absorbed to reach a specific operating point (under the same marginal conditions) reaches its minimum.

[0047] Compared to the prior art, the arrangement of the fluid connection allows the pressure level to be maintained at an optimum level throughout the entire operating range of the scroll compressor. For example, prior art backpressure systems with an inlet to the high-pressure chamber itself can only be optimally adjusted in operating points for air conditioning (AC), but not simultaneously in operating points for heat pumping mode, as such systems typically have excessively high backpressure levels in these operating points.

[0048] Due to the energetically favorable fluid connection, the back-pressure system also has a higher efficiency. Compared to back-pressure systems with a fluid connection to the high-pressure chamber, the fluid or refrigerant-oil mixture is extracted directly from the compressor chamber before it is fully compressed. From an energetic point of view, this is more advantageous than extracting the refrigerant from the high-pressure chamber only after it is fully compressed and then expanding it to the back-pressure level. This results in a lower gas temperature inside the back-pressure chamber, thereby improving the load capacity and service life of the scroll compressor bearings, in particular the center plate bearings (central plate bearings) or the bearings of the orbiting scroll body.

[0049] Furthermore, the back-pressure system makes it impossible to disengage the orbiting scroll from the stationary scroll in compressor mode. In compressors where the back-pressure system is unable to provide sufficient axial force compensation for each operating point (e.g., heat pumping point), a so-called disengagement phenomenon occurs. Here, the orbiting scroll separates axially from the stationary scroll. Due to the resulting leakage gaps, compression is completely interrupted or extremely inefficient.

[0050] This disengagement process is often self-reinforcing. If disengagement begins during a complete compression cycle, the higher pressure differential causes refrigerant to flow from the innermost compressor chamber to the subsequent outer compressor chamber, raising the pressure in the outer compressor chamber. Consequently, a greater axial compressive force is required from the backpressure chamber. Without this compressive force, the axial leakage gap increases. This situation continues until compression ceases completely, or at least until a certain compression ratio can no longer be achieved.

[0051] Since the back-pressure system observes the entire compression process, it reacts adaptively to leaks that increase the pressure in the external compressor chamber, wherein at least one external fluid connection also increases the pressure level in the back-pressure chamber. This results in an almost "dynamic feedback". For example, a particularly high reaction speed of the back-pressure system can be achieved by introducing a straight or direct fluid connection into the base plate of the orbiting scroll body. Preferably, the radially outer fluid connection has a larger diameter than the radially inner fluid connection, so that the pressure increase caused by the leak is quickly adjusted.

[0052] In a preferred design, no fluid connection is coupled to the low-pressure chamber. In other words, no fluid connection is provided in the area of ​​the suction chamber. This means that the fluid connection is arranged only in the inner area of ​​the scroll component, that is, in the area of ​​the extrusion chamber, the injection chamber, and the discharge chamber. As a result, the back-pressure chamber is not connected to the suction side or the low-pressure chamber. This reduces the lost mass flow in the scroll compressor.

[0053] In contrast to backpressure systems with a fluid connection to the suction side, the refrigerant-oil mixture returns directly to one of the outer extrusion chambers. This prevents the refrigerant from expanding completely from the backpressure level to the suction pressure level of the low-pressure chamber. Therefore, in scroll compressors, the mass flow lost by the backpressure system is not a "complete loss" because the entire mass flow is returned to the compressor chamber.

[0054] An additional or further aspect of the present invention provides that the fluid connections are arranged in such a way that at the moment of the orbiting movement of the movable scroll body, the fluid connections are not simultaneously blocked or closed. In other words, at any moment at least one fluid connection is open. This makes it possible to bring about a pressure balance in the system or in the back-pressure chamber when the scroll compressor is switched off. This means that the pressure in the back-pressure chamber can also be reduced. Otherwise, when the scroll compressor is (re)started in time, there would be high axial extrusion forces without the sealing force of the compressor chamber acting in opposition. As a result, the wear of the axial contact surfaces is increased and a high "starting torque" that must be applied by the drive of the scroll compressor is increased.

[0055] In one conceivable embodiment, the depression has a circular cross-sectional shape, thereby enabling simple and inexpensive production as milling or drilling.

[0056] In a suitable development, the or each fluid connection is implemented as two axially mutually converging holes, wherein the holes have different diameters. The wider hole is oriented toward the back pressure chamber, wherein the narrower hole is directed toward the depression of the base plate.

[0057] The or each fluid connection is provided with a filter element, for example. The filter element is provided here to improve the robustness against particles, in particular in the case of fluid connections with a small diameter, and is suitable and designed for this purpose.

[0058] The ratio of the flow cross sections of the fluid connections can vary to a small extent. However, if simple holes are used as fluid connections, a certain minimum size or minimum diameter is required. This is due to the requirement for a certain reaction speed of the backpressure system, which is related to the filling speed of the backpressure chamber. In addition, a certain particle resistance should be achieved. This means that the smallest particles cannot directly block or obstruct the holes or fluid connections. In the automotive industry, particle sizes of up to 200 microns are generally permitted.

[0059] The smaller the flow diameter of the fluid connection is dimensioned, the less the mass loss decreases. By using a fine filter fabric within the fluid connection (e.g., a beta filter with a mesh size of 40 μm), it is also possible to use very fine fluid connections, i.e., fluid connections with a small diameter, for example, in the range of approximately 0.1 mm.

[0060] The refrigerant drive according to the present invention is embodied, in particular, as a refrigerant compressor, for example, as an electric scroll compressor for a motor vehicle. The refrigerant drive is designed and adapted for compressing refrigerant in the air conditioning system of a motor vehicle. The refrigerant drive comprises an electric drive that is controlled and / or regulated by power electronics. The drive is coupled to a compressor head in terms of drive technology, wherein the compressor head is embodied as the scroll compressor described above. The advantages and design concepts listed for the scroll compressor are also transferable to the refrigerant drive, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The following is a more detailed explanation of the embodiments of the present invention with reference to the accompanying drawings, wherein:

[0062] Figure 1 A cross-sectional view showing an electric refrigerant compressor having a scroll compressor with an integrated back pressure system;

[0063] Figure 2 A perspective view showing an orbiting scroll of a scroll compressor;

[0064] Figure 3 A perspective view showing a stationary scroll of a scroll compressor;

[0065] Figure 4 A cross-sectional view showing a scroll compressor according to a second embodiment;

[0066] Figure 5 A cross-sectional view showing a radially outer fluid connection of a scroll compressor;

[0067] Figure 6 A cross-sectional view showing a radially inner fluid connection of a scroll compressor;

[0068] Figure 7 A shaft angle-pressure diagram showing the compression process of a scroll compressor;

[0069] Figure 8 A perspective view showing a stationary scroll of a third embodiment; and

[0070] Figure 9 A cross-sectional view showing a scroll compressor according to a third embodiment.

[0071] Parts and dimensions that correspond to one another are always provided with the same reference numerals in all figures. DETAILED DESCRIPTION

[0072] Figure 1The refrigerant drive 2 shown in the figure is preferably installed as a refrigerant compressor in a refrigerant circuit (not shown in detail) of an air conditioning system of a motor vehicle. The electric refrigerant compressor 2 has an electric (electric) drive 4 and a scroll compressor 6 coupled to the drive as a compressor head. The scroll compressor 6 is also referred to as compressor 6 for short hereinafter.

[0073] The drive 4 on the one hand and the compressor 6 on the other hand are designed, for example, in a modular manner, so that the drive 4 can be coupled, for example, to different compressors 6. The transition region formed between the modules 4 and 6 has a mechanical interface in the form of an end shield 8. The compressor 6 is connected to the drive 4 via the end shield 8 in terms of drive technology.

[0074] The drive 4 has a pot-shaped drive housing 10 having two housing parts 10a and 10b which are separated from one another in a fluid-tight manner by a monolithically integrated housing intermediate wall (partition wall) 10c within the drive housing 10. The drive housing 10 is preferably manufactured from aluminum as a die-cast part.

[0075] The compressor-side housing subregion is designed as a motor housing 10a for accommodating an electric motor 12. The motor housing 10a is closed on the one hand by a (housing) intermediate wall 10c and on the other hand by an end shield 8. The housing part opposite the intermediate wall 10c is designed as an electronics housing 10b, in which power electronics (motor electronics), not shown in detail, are accommodated, which control and / or regulate the operation of the electric motor 12 and thus of the compressor 6.

[0076] The electronics housing 10b is closed by a housing cover (electronics cover) 14 on the end side facing the drive 4 away from the compressor 6. When the housing cover 14 is open, the power electronics are mounted in an electronics compartment 16 formed by the electronics housing 10b and can also be easily accessed for maintenance or repair purposes when the housing cover 14 is removed.

[0077] Approximately at the level of the electric motor 12, the driver housing 10 has a (suction) inlet or suction port (inlet), not shown in greater detail, for connection to the refrigerant circuit of an air conditioning system. Fluid, particularly suction air, flows into the driver housing 10, particularly the motor housing 10a, via this inlet. From the motor housing 10a, the fluid flows through the end cap 10 to the compressor 6. The refrigerant is then compressed or squeezed by the compressor 6 and flows out at a (refrigerant) outlet 18 (outlet) on the bottom side of the compressor 6 into the refrigerant circuit of the air conditioning system.

[0078] The outlet 18 is formed on the bottom of the pot-shaped (compressor) housing 20 of the compressor 6. In the connected state, the inlet forms the low-pressure or suction side, while the outlet 18 forms the high-pressure or pumping side of the refrigerant compressor 2.

[0079] The brushless electric motor 12 comprises a rotor 24 coupled to a motor shaft 22 in a rotationally fixed manner and rotatably arranged within a stator 26. The motor shaft 22 is rotatably supported by two bearings 28. One bearing 28 is arranged in a bearing seat 30 formed on the housing bottom or intermediate wall 10c of the drive housing 10. The other bearing 28 is accommodated in an end cap 8. The end cap 8 has a sealing ring 32 for sealing against the motor shaft 22.

[0080] The scroll compressor 6 includes a movable scroll body (scroll member) 34 arranged in the compressor housing 20 . Figure 2 The scroll body 34 shown separately in the figure is coupled to the motor shaft 22 of the electric motor 12 by means of a balancing weight 36 as a rocker or eccentric via two coupling pins or journals 38, 40. The journal 38 is designed as a so-called eccentric pin and the journal 40 is designed as a so-called stop pin.

[0081] The compensating weight 36 is supported in a bearing 42 held in the movable scroll 34. During operation of the scroll compressor 6, the movable scroll 34 is driven in an orbiting manner.

[0082] The scroll compressor 6 also has a rigid scroll body (scroll member) 44 which is fixed in the compressor housing 20, i.e. fixed relative to the housing. Figure 3 The two vortices (vortex components) 34, 44 are nested within one another using their spiral or helical spiral walls (vortex walls, vortex spirals) 34a, 44a, which extend axially from their respective base plates 34b, 44b. The spiral walls 34a, 44a are merely exemplarily referenced in the figures. The vortex 44 also has a surrounding boundary wall 44c that forms its outer periphery.

[0083] The scroll bodies 34, 44 are connected to the motor space of the motor housing 10a via the suction or low-pressure chamber 46 of the compressor housing 22. In compressor mode, fluid is conveyed from the low-pressure chamber 46 to the high-pressure chamber 48 of the compressor housing 20. An oil separator 50, embodied as a cyclone separator, is arranged in the high-pressure chamber 48. The separated oil is returned via an oil return 52 for lubrication of the moving parts.

[0084] A flutter valve (finger spring valve) 54 is arranged between the swirl body 44 and the high-pressure chamber 48, i.e., on the bottom of the base plate 44b, as a covering or closing component, which covers the central, high-pressure-side discharge opening 56 of the swirl body 44. The flutter valve 54 is particularly a check valve, which opens in the flow direction and automatically closes again, i.e., covers the discharge opening 56, without further external actuation, solely due to the pressure difference between the two valve sides.

[0085] The discharge opening 56 is also referred to below as the main discharge port. Radially spaced from the main discharge port 56 are two additional discharge openings 58 ( Figure 4 ), namely as so-called pre-outlets or auxiliary outlets (Pre-Outlets). The discharge opening 58 is also referred to as a secondary valve port hereinafter.

[0086] The flutter valve 54 is provided on the one hand as a main valve for the discharge opening 56 and on the other hand as a pre-outlet valve or auxiliary outlet valve for the discharge opening 58 of the scroll element 44, with which it is used to avoid excessive squeezing of the refrigerant 2 in compressor mode. This ensures pressure-regulated refrigerant injection from the discharge openings 56, 58.

[0087] Between the A-side bearing cover 8 (center plate) and the movable scroll 34, a backpressure chamber (backpressure chamber) 60 is located as part of a backpressure system (not specifically labeled). The backpressure chamber 60 is bounded in the compressor housing 20 by the base plate 34b of the movable scroll 34. The backpressure chamber 60 partially extends into the base plate 34b of the movable scroll 34. The backpressure chamber 60 is sealed relative to the base plate 34b by a seal 62.

[0088] When the refrigerant drive 2 is in operation, the refrigerant is introduced into the drive housing 10 through the inlet and there into the motor housing 10a. This area of ​​the drive housing 10 forms the suction or low-pressure side of the scroll compressor 6. The housing intermediate wall 10b prevents the refrigerant from entering the electronics compartment 16. Within the drive housing 10, a refrigerant-oil mixture is drawn through the opening along the rotor 24 and stator 26 into the suction or low-pressure chamber 46 of the scroll compressor 6. The mixture consisting of refrigerant and oil is compressed by the scroll compressor 6, wherein the oil is used to lubricate the two scroll bodies 34 and 44, thereby reducing friction and thus improving efficiency. The oil is also used for sealing to prevent the refrigerant present between the two scroll bodies (scroll components) 34, 44 from leaking out uncontrollably.

[0089] The compressed refrigerant-oil mixture is directed via a central main discharge port 56 in the base 44b of the stationary scroll 44 into the high-pressure chamber 48 within the compressor housing 20. Within the oil separator 50, the refrigerant-oil mixture is set into rotation. Due to its increased inertia and mass, the heavier oil is drawn toward the walls of the oil separator 50 and collected in the lower region under the influence of gravity g, while the refrigerant is discharged upward or laterally through the outlet 18. The oil is then directed back to the electric motor 12 via an oil return line 52 extending through the lower or lateral region of the oil separator 50. In other words, the high-pressure chamber 48 is fluidically connected to the low-pressure side via the oil return line 52. The oil return line 52 is embodied, for example, as a bypass channel with a throttle mechanism in the form of a baffle.

[0090] "Axial" or "axial direction A" is understood here and below in particular as a direction parallel (coaxial) to the axis of rotation of the electric motor 12, i.e., a direction in the longitudinal direction of the refrigerant drive 2. Correspondingly, "radial" or "radial direction R" is understood here and below as a direction oriented perpendicular (transverse) to the axis of rotation of the electric motor 12 along the radius of the electric motor 12 or the scroll component 34, 44. "Tangential" or "tangential direction T" is understood here and below in particular as a direction along the circumference (circumferential direction, azimuthal direction) of the electric motor or the circumference of the scroll component 34, 44, i.e., a direction perpendicular to the axial direction and the radial direction. In the figures, the direction of gravity is marked with g and is shown by way of example.

[0091] When the compressor 6 is assembled, the spiral body or spiral wall 34a of the movable scroll element 34 is embedded in the free space or intermediate space of the spiral wall 44a of the stationary scroll element 44. Between the scroll bodies 34, 44—that is, between their spiral walls or spiral bodies 34a, 44a and the base plates 34b, 44b—a compressor chamber is formed, the volume of which changes during the compressor mode. Hereinafter, the compressor chamber is also divided into a suction chamber S, a compression chamber K, and a discharge chamber D.

[0092] The suction chamber S is open here to the low-pressure side, i.e. the low-pressure chamber 46. As soon as the suction chambers S are closed by the orbiting movement of the vortex body 34, they become extrusion chambers K, the sickle-shaped volume of which is gradually compressed towards the center of the spiral body during the orbiting movement. The angular positioning of the motor shaft 22 when the suction chamber S is closed is also referred to as the 0° position below. The two radially innermost extrusion chambers K form the injection chamber D here. The injection chambers D are connected or combined in a process also referred to as "merging" to form a common discharge chamber DD, which transports the compressed refrigerant oil mixture to the high-pressure chamber 48 by means of the discharge opening 56. The angular positioning of the motor shaft 22 when the injection chambers D merge into the discharge chamber DD is also referred to as the merging angle or merging angle below.

[0093] The back pressure system according to the invention enables flexible and effective matching of the pressure in the back pressure chamber 60. In an embodiment, the back pressure chamber 60 is connected to the compressor chamber via two fluid connections 64, 66 for this purpose. Two or more fluid connections are appropriately provided in a vortex body with a vortex body length of 720° (when making full use of symmetry). Each fluid connection connects a different compressor chamber to the back pressure chamber 60, wherein no fluid connection 64, 66 is connected to the low pressure chamber 46. The fluid connections 64, 66 are introduced into the spiral wall 34a of the orbiting vortex body 34 as axial holes. Figure 5 The fluid connection 66 is shown separately in FIG. Figure 6 The fluid connection 64 is shown separately in FIG.

[0094] As from Figure 5 and Figure 6 As can be seen more clearly in the cross-sectional view of FIG, the fluid connections 64, 66 are each embodied as two axially interconnected, for example coaxial, holes of different diameters. The larger hole opens into the backpressure chamber 60, while the smaller hole opens into the compressor chamber or recess 68. The smaller hole serves as a throttle element for flow regulation, while the larger free hole serves only to simplify production.

[0095] For example, the circular recess 68 in the base plate 44b of the stationary scroll 44 is dimensioned in such a way that leakage beyond the spiral wall 34a is not possible. This means that the recess 68 has a diameter that is smaller than the width of the spiral wall 34a.

[0096] The fluid connections 64, 66 are arranged in such a way that they are not blocked or closed together at any time during the orbiting motion of the movable scroll 34. In other words, at least one fluid connection 64, 66 is preferably open at any time.

[0097] During the compression cycle, the two fluid connections 64, 66 act in respectively different compression ranges. In particular, the entire compression cycle ( Figure 7 ) is essentially in active fluid connection with the back-pressure chamber 60. The diameters of the fluid connections 64, 66 are weighted by the cross-sectional area of ​​the associated compressor chamber. This means that the inner fluid connection 64 has a smaller diameter than the subsequent outer fluid connection 66.

[0098] The fluid connections 64, 66 are introduced into the axial contact surface of the spiral wall 34a (spiral tip) of the orbiting vortex 34. Figure 3 As can be seen in the figure, the base plate 44b of the stationary scroll 44 has a certain number of, for example, recessed depressions 68, which are swept or rolled over at least in sections by the contact surface fluid connections 64, 66 during the movement of the scroll 34 running along the track, so that the fluid connections 64, 66 are at least temporarily open to the respective compressor chamber. In the embodiment shown, four recesses 68 are provided in the scroll 44 for each fluid connection 64, 66, which are distributed along the circular movement path of the fluid connections 64, 66 ( Figure 4 ).exist Figure 4 In the exemplary embodiment, only three recesses 68 are assigned to the fluid connection 64, wherein the outlet opening 56 acts as a fourth recess. The recesses 68 are provided with reference numerals in the figures only as an example.

[0099] Once the orbiting scroll 34 is completely in contact with the stationary scroll 44 in the axial direction A, the fluid connections 64, 66 of the contact surface are normally completely blocked. However, the fluid connections 64, 66 are opened in a time-controlled or timed manner by a recess or depression 68 in the bottom of the stationary scroll 44, wherein Figure 5 and Figure 6 In the diagram, the mass flow when fluid connections 64 and 66 are open is indicated by arrows. From a static perspective, the pressure is effectively the same as when the fluid connections are normally open. However, this has the advantage of significantly reducing the refrigerant mass flow losses due to the backpressure system. Furthermore, the response time of the scroll compressor 6 during startup is improved.

[0100] Combine Figure 7 The working of the backpressure system and the timing of the clock control are explained in more detail. Figure 7In the schematic shaft angle-pressure diagram, the shaft angle WW of the motor shaft 22 in radians (rad) is horizontal, i.e. plotted along the abscissa axis (X-axis), while the pressure p in, for example, bar is plotted along the ordinate axis (Y-axis). Figure 7 7. Three horizontal lines 70, 72, 74 are shown in FIG. 7, which represent different pressure levels. Line 70 corresponds to the high pressure level of the high pressure chamber 48, line 72 shows the back pressure level of the back pressure chamber 60, and line 74 shows the low pressure level of the low pressure chamber 46.

[0101] exist Figure 7 The diagram of FIG. 7 shows three compression curves 76 , 78 , 80 for successive compression cycles, wherein the compression curve 78 represents the current compression cycle, and wherein the compression curve 76 represents the preceding compression cycle, and the compression curve 80 represents the subsequent compression cycle.

[0102] In the range 82 of the compression curve 78, the outer fluid connection 66 is opened in a clocked manner, so that an effective fluid connection exists between the displacement chamber K and the backpressure chamber 60. At point 84, there is a merging angle, meaning that the injection chamber D merges into the discharge chamber DD. In the range 86, the inner fluid connection 64 is open, so that an effective fluid connection exists between the injection chamber D or the discharge chamber DD and the backpressure chamber 60.

[0103] During the compression cycle 78, the two fluid connections 64, 66 act in respectively different compression ranges. Depending on the high pressure level 70 and the low pressure level 74, a specific back pressure is necessary to ensure axial force compensation of the back pressure system. The refrigerant mass flow 88 (the refrigerant mass flow also always refers to a certain oil mass flow component) is guided into and out of the back pressure chamber 60 via the two fluid connections 64, 66. The mass flow 88 is Figure 7 It is shown as a vertical arrow in FIG.

[0104] The driving force here is the pressure difference between the compression chambers K, D, DD and the back-pressure chamber. If the pressure of the fluidically connected compression chamber is lower than the pressure in the back-pressure chamber, the refrigerant flows from the back-pressure chamber to the compression chamber (start of range 82 and range 84). If the opposite is true, the refrigerant flows from the compression chamber to the back-pressure chamber.

[0105] An internal oil circuit is realized via the fluid connections 64 , 66 , which conveys oil to the bearings 28 , 42 in the backpressure chamber 60 and thus lubricates them.

[0106] Figure 8 and 9FIG. 3 shows a third embodiment of a scroll compressor 6. In this embodiment, the recess 68' is not circular, but is approximately elliptical, egg-shaped, or kidney-shaped. Six recesses 68' are provided for each of the fluid connections 64 and 66, and are distributed along the circular path of the fluid connection ( Figure 9 ). Thus, six opening and six closing cycles are achieved. This still allows for sufficiently precise monitoring of the compression process, but the time of an active fluid connection can be reduced to half compared to a hole with a permanent fluid connection. The recesses 68' are provided with reference numerals in the figures only as an example.

[0107] The present invention is not limited to the above-described embodiments. On the contrary, other variants of the present invention can be derived therefrom by a person skilled in the art without departing from the subject matter of the present invention. In particular, all individual features described in connection with these embodiments can also be combined with one another in other ways without departing from the subject matter of the present invention.

[0108] Thus, all embodiment variants can be implemented in the same manner in the orbiting scroll 34 and the stationary scroll 44, or vice versa. The same positioning conditions apply to the scroll 44 as to the scroll 34. Furthermore, the introduction of the fluid connection can also be distributed over the scrolls 34, 44 and thus partially implemented in the movable scroll 34 and the stationary scroll 44.

[0109] Reference Signs List

[0110] 2 Refrigerant Driver

[0111] 4 Drivers

[0112] 6 Scroll compressor

[0113] 8 Bearing end cover

[0114] 10 Driver housing

[0115] 10a Motor housing

[0116] 10b Electronic device housing

[0117] 10c Middle wall

[0118] 12 Electric Motor

[0119] 14 Housing cover

[0120] 16 Electronics Box

[0121] 18 Exit

[0122] 20 Compressor housing

[0123] 22 Motor shaft

[0124] 24 rotors

[0125] 26 stator

[0126] 28 bearings

[0127] 30 bearing seat

[0128] 32 sealing ring

[0129] 34 Vortex

[0130] 34a Spiral Wall

[0131] 34b base plate

[0132] 36 Balance Weight

[0133] 38 journal

[0134] 40 journal

[0135] 42 bearings

[0136] 44 Vortex

[0137] 44a Spiral Wall

[0138] 44b base plate

[0139] 44c Boundary Wall

[0140] 46 Low-pressure chamber

[0141] 48 High-pressure chamber

[0142] 50 Oil separator

[0143] 52 Oil return section

[0144] 54 Flutter Valve

[0145] 56 Discharge opening / main discharge port

[0146] 58 Discharge opening / auxiliary valve port

[0147] 60 Back pressure chamber

[0148] 62 seals

[0149] 64 fluid connection

[0150] 66 Fluid connection

[0151] 68, 68' recessed part

[0152] Lines 70, 72, and 74

[0153] 76, 78, 80 compression change curve

[0154] 82 Range

[0155] 84 points

[0156] 86 Range

[0157] 88 Refrigerant mass flow

[0158] A Axial direction

[0159] R radial direction

[0160] T tangential direction

[0161] g gravity

[0162] S Suction chamber

[0163] K Extrusion Chamber

[0164] D Injection chamber

[0165] DD discharge chamber

[0166] WW shaft angle

[0167] p pressure

Claims

1. A scroll compressor (6) with an electric refrigerant drive (2), said scroll compressor having: a housing (20) having a low-pressure chamber (46) and a high-pressure chamber (48) as well as compressor chambers (S, K, D, DD) and a back-pressure chamber (60), - a stationary scroll (44) having a base (44b) and a spiral wall (44a), wherein: The base plate (44b) of the stationary scroll (44) defines a high pressure chamber (48), a movable scroll (34), said movable scroll having a base plate (34b) and a spiral wall (34a), said spiral wall being embedded in the spiral wall (44a) of the stationary scroll (44) and forming the compressor chamber (S, K, D, DD) together with the spiral wall of the stationary scroll, wherein the base plate (34b) of the movable scroll (34) delimits the back pressure chamber (60), wherein at least one fluid connection (64, 66) is provided, which connects the back-pressure chamber (60) to one of the compressor chambers (K, D, DD), wherein the at least one fluid connection (64, 66) is introduced into an axial contact surface of the spiral wall of one of the spiral bodies, said contact surface being in contact with the base plate of the respective other spiral body, and - wherein the base plate of the further scroll body has several depressions (68, 68') which are swept at least in sections by at least one fluid connection (64, 66) of the contact surface during the swirling movement, so that the fluid connection (64, 66) is at least temporarily opened to the corresponding compressor chamber (K, D, DD), At least two fluid connections (64, 66) are provided in the stationary and / or movable scroll (44, 34), via which the back-pressure chamber (60) is connected to a number of different compressor chambers (K, D, DD) corresponding to the number of the fluid connections (64, 66). A plurality of recesses are formed on the base plate of the scroll body for each fluid connection portion.

2. The scroll compressor (6) according to claim 1, It is characterized in that The recesses (68, 68') each have a diameter that is smaller than the width of the spiral wall (34a) sweeping across the recess.

3. The scroll compressor (6) according to claim 1 or 2, It is characterized in that The at least one fluid connection (64, 66) is introduced into the spiral wall (34a) of the movable scroll (34), while the recess (68, 68') is introduced into the base plate (44b) of the stationary scroll (44).

4. The scroll compressor (6) according to claim 1, It is characterized in that A first fluid connection (64) is coupled to the radially innermost compressor chamber (DD), and a second fluid connection (66) is arranged outwardly offset from the first fluid connection (64) by a helical angle of 320° to 400°.

5. The scroll compressor (6) according to any one of claims 1 to 2, It is characterized in that No fluid connections (64, 66) are coupled to the low pressure chamber (46).

6. The scroll compressor (6) according to any one of claims 1 to 2, It is characterized by: The fluid connections (64, 66) are arranged in such a way that at any moment of movement of the movable scroll (34), the fluid connections (64, 66) are not both closed.

7. The scroll compressor (6) according to any one of claims 1 to 2, It is characterized by: The recessed portion (68, 68') has a circular cross-sectional shape.

8. The scroll compressor (6) according to any one of claims 1 to 2, It is characterized by: The at least one fluid connection (64, 66) is embodied as two axial bores communicating with one another, wherein the bores have different diameters.

9. An electric refrigerant drive (2) having power electronics and an electric drive (4) and a scroll compressor (6) according to any one of claims 1 to 8 coupled to the electric drive as a compressor head.

Images