Scroll compressor with direct oil return from the oil separator into the compression section

Abstract

The present invention relates to a scroll compressor (1) for compressing a fluid, the scroll compressor (1) including a compression section (10) having an inlet (11) for drawing in the fluid, an outlet (12) for discharging the compressed fluid, a fixed disk (20) having a fixed scroll (21), and an orbiting disk (30) having an orbiting scroll (31), the orbiting disk (30) being orbitable relative to the fixed disk (20) for transporting the fluid from the inlet (11) to the outlet (12) and compressing it in the process. The scroll compressor (1) includes an oil separator (45) for separating oil from the compressed fluid, and a direct oil return (50) for returning oil directly from the oil separator (45) into the compression section (10), the direct oil return (50) including at least one orifice opening (59a, 59b). To enable efficient operation, the direct oil return (50) further includes a degassing chamber (54) disposed between the first flow valve (53) and the orifice openings (59a, 59b), and a fluid return (70) for returning fluid from the degassing chamber (54) into the compression section (10).

Description

Technical Field

[0001] The present invention relates to a scroll compressor for compressing a fluid by a compression section, comprising an inlet of the compression section for sucking the fluid into the compression section, an outlet of the compression section for discharging the compressed fluid from the compression section, a fixed disk having a fixed scroll, and a swivel disk having a swivel scroll.

Background Art

[0002] Scroll compressors are used, for example, as compressors in air conditioners, particularly in air conditioners for motor vehicles with a prime mover. Furthermore, they are used as heat pumps. They are characterized by a particularly uniform, low-vibration and quiet operation compared to other types of compressors.

[0003] The compression section forms the core of the scroll compressor. As the swivel disk swivels relative to the fixed disk, a fluid, particularly a gas or a gas mixture, is compressed. For this purpose, the swivel scroll and the fixed scroll are arranged in combination with each other so as to form a compression space for the fluid therebetween. With respect to the fixed scroll, each compression space moves from the outer region of the fixed scroll to its center together with the fluid enclosed therein. At this time, the space available for the fluid gradually becomes smaller, and the fluid is compressed.

[0004] During operation, the maximum pressure of the fluid is achieved at the outlet of the compression section. The fluid reaches the compression section at the suction pressure and is discharged therefrom at a significantly higher discharge pressure.

[0005] The fluid gradually compressed between the swivel disk and the fixed disk pushes the swivel disk and the fixed disk in a direction away from each other. Therefore, a separating force acts on the swivel disk. The strength of the separating force depends particularly on the suction pressure, the discharge pressure and the geometric shape of the compression section. Typically, a change in the discharge pressure has a more significant effect on the contact pressure than a change in the suction pressure.

[0006] To achieve high compression, the compression space formed by the engagement of the fixed disk and the orbiting disk and moved towards the center must be sufficiently sealed. The orbiting disk is firmly and airtightly pressed against the fixed disk, and the orbiting disk receives a contact pressure on the back surface opposite to the fixed disk so that the fluid does not exit the compression section. For this purpose, a contact pressure chamber is provided on the back surface of the orbiting disk. The contact pressure pushes the orbiting disk with the contact force in the direction of the fixed disk.

[0007] The biting-in of the orbiting scroll into the fixed disk and the biting-in of the fixed scroll into the orbiting disk cause friction during operation. An electric scroll compressor typically operates in a rotational speed range of 500 - 12000 min -1 and in that case, the high friction can be detected through deteriorated efficiency.

[0008] Oil is introduced into the contact pressure chamber to lubricate the orbiting disk. Further, an oil supply line from the contact pressure chamber through the orbiting disk can be formed. Through the oil supply line, the oil can flow from the contact pressure chamber between the fixed disk and the orbiting disk.

[0009] The oil contained in the fluid discharged from the scroll compressor should be as little as possible. An excessive amount of oil in the discharged fluid may affect the efficiency of the downstream components through which the discharged fluid further flows. For example, the efficiency of the refrigerant circuit may decrease by the mixing of more oil.

[0010] Typically, a scroll compressor is the only component within a refrigerant circuit that requires oil to lubricate mechanically stressed parts within the refrigerant circuit itself. Usually, a refrigeration circuit can be operated in different operating states. The efficiency of the refrigeration circuit depends greatly on its operating state. An excessive amount of oil can, for example, cause the surfaces inside the heat exchanger to be wetted with oil. Thereby, the heat transfer efficiency in each heat exchanger decreases. As a result, the efficiency of the evaporator and the condenser decreases. Consequently, the refrigerant circuit has to be operated at a higher pressure ratio overall in order to provide the required refrigeration capacity. Thus, an excessive amount of oil reduces the overall efficiency and, due to the increase in the pressure ratio, increases the stress on the mechanical components inside the scroll compressor.

[0011] Thus, the compressed fluid is led through an oil separator after the compression section. The oil separator separates at least partially the oil from the compressed fluid. The separated oil is returned into the contact pressure chamber via the (second) oil return.

[0012] During operation of the scroll compressor, the oil in the contact pressure chamber is subject to a contact pressure. The orifice opening of the oil supply line is arranged in the central region of the compressor channel of the orbiting disk formed by the orbiting scroll on the orbiting disk. Due to this positioning and the continuous mass flow of the mixture of oil and refrigerant coming from the high-pressure side, a contact pressure of medium pressure level is generated in the contact pressure chamber. The contact pressure presses the orbiting disk with a contact force in the direction of the fixed disk. The positioning in the central region contributes significantly to the generation of a sufficiently large contact pressure as desired. The contact pressure is variable and depends on the operating pressure. Thereby, the seal between the fixed disk and the orbiting disk is ensured at all operating points and the friction is kept as low as possible.

[0013] However, due to this positioning of the orifice opening of the oil supply line, the outer radial region between the fixed disk and the orbiting disk is not optimally supplied with oil. As a result, the friction increases, the efficiency decreases, and in certain situations, the service life of the scroll compressor is also shortened.

Summary of the Invention

Problems to be Solved by the Invention

[0014] The problem of the present invention is to create a scroll compressor that enables more efficient operation and has higher reliability.

Means for Solving the Problems

[0015] The above problem is solved by a scroll compressor for compressing a fluid.

[0016] A scroll compressor for compressing a fluid includes the following: A compression section having: · An inlet of the compression section for sucking the fluid into the compression section, · An outlet of the compression section for discharging the compressed fluid from the compression section, · A fixed disk having a fixed scroll, and · A swivel disk having a swivel scroll, which is swivellable with respect to the fixed disk along the compression direction in order to transport the fluid from the inlet of the compression section to the outlet of the compression section and compress it there, and An oil separator for separating oil from the compressed fluid

[0017] The scroll compressor is provided with a direct oil return for directly returning oil from the oil separator into the compression section, and the direct oil return is provided with at least one orifice opening.

[0018] During operation, the direct oil return continuously returns oil from the oil separator into the compression section. Thereby, the friction in the compression section is reduced. In this way, the direct oil return enables more efficient operation of the scroll compressor. Furthermore, the wear in the compression section is reduced. Thereby, the reliability and service life of the scroll compressor are increased.

[0019] During operation, the oil separator is (at least substantially) subject to the discharge pressure. The present invention utilizes the difference between the pressure in the oil separator and the pressure of the fluid at the orifice opening to directly and purposefully return the oil from the oil separator back into the compression section. An important advantage is that the oil flow is driven by a direct oil return according to the pressure ratio of the discharge pressure to the suction pressure. The amount of oil returned is substantially dependent on this pressure ratio. For example, at a rotational speed of 600 min -1 , at an intake pressure of 3 bar and a discharge pressure of 15 bar, this amount is the same as for an intake pressure of 3 bar and a discharge pressure of 15 bar, but at a rotational speed of 8500 min -1 .

[0020] The amount of oil returned by the direct oil return is (at least substantially) independent of the rotational speed of the scroll compressor and (at least substantially) independent of the exact discharge pressure. Even at low rotational speeds, the direct oil return returns a sufficient amount of oil into the compression section. The direct oil return is therefore suitable for lubricating the compression section in various load states of the scroll compressor. In particular, it improves lubricity at low rotational speeds.

[0021] Furthermore, the direct oil return functions independently of the contact pressure. Even if the contact pressure decreases, as long as the discharge pressure remains sufficiently high, the direct oil return further returns oil to the compression section.

[0022] Furthermore, the oil is better retained within the scroll compressor. There is no need to supply oil that has leached from the contact pressure chamber into the compression section within the inlet region or that is led to the inlet of the compression unit through the outer portion of the refrigerant circuit. The outer portion of the refrigerant circuit means the region of the refrigerant circuit outside the scroll compressor. The fluid behind the oil separator contains less oil. Less oil is led through the outer portion of the refrigerant circuit. Typically, the higher the proportion of oil in the fluid in the outer portion of the refrigerant circuit, the worse the thermodynamic properties of the refrigerant-oil mixture. The proposed direct oil return significantly reduces the oil circulation ratio (OCR) of the refrigerant circuit. The direct oil supply pinpoints the oil into the inlet region of the compression unit. Thereby, the efficiency of the refrigerant circuit is improved.

[0023] In particular, at low rotational speeds, in a conventional scroll compressor, since the mass flow rate of the refrigerant through the outer portion of the refrigerant circuit is small, the risk of oil unintentionally remaining in the outer portion of the refrigerant circuit increases.

[0024] Conversely, during operation, inside the scroll compressor, particularly inside the compression section, the proportion of oil available for lubrication increases. Active direct oil return reduces the total amount of oil required for the operation of the scroll compressor. Thereby, the cost is reduced and the weight of the refrigerant circuit is reduced. As a result, for example, the efficiency of a vehicle equipped with a scroll compressor is improved.

[0025] The outlet of the compression unit is at least substantially arranged at the center of the fixed disk. In particular, the outlet of the compression unit can be arranged exactly at the center of the fixed disk.

[0026] The stationary scroll forms a spiral compressor channel of the stationary disk that extends from the outer end of the stationary scroll to the inner end of the stationary scroll. The inner end of the stationary scroll is at the center of the stationary scroll. It is at the outlet opening of the stationary disk. The outlet of the compression section includes this outlet opening. In particular, this outlet opening can form the outlet of the compression section.

[0027] The stationary scroll can be disposed on the stationary base of the stationary disk. The stationary scroll can be formed from a wall that extends away from the stationary base parallel to the central axis of the stationary disk. Preferably, the end face of the stationary scroll that faces away from the stationary base along this central axis is formed flat and parallel to the stationary base.

[0028] The outlet opening can include a hole in the stationary base. In particular, the outlet opening can be designed as a hole in the stationary base.

[0029] Similarly, the orbiting scroll forms a spiral compressor channel of the orbiting disk that extends from the outer end of the orbiting scroll to the inner end of the orbiting scroll. In the present disclosure and the claims, the term "compressor channel" without further qualification refers only to the compressor channel of the stationary disk, unless otherwise specified and unless something else is forced by the context.

[0030] The orbiting scroll can be disposed on the orbiting base of the orbiting disk. The orbiting scroll can be formed from a wall that extends away from the orbiting base parallel to the central axis of the orbiting disk. Preferably, the end face of the orbiting scroll that faces away from the orbiting base along this central axis of the orbiting disk is formed flat and parallel to the orbiting base. The orbiting base can be parallel to the stationary base.

[0031] The stationary scroll and the orbiting scroll can each have exactly one scroll arm.

[0032] The scroll compressor comprises a swivel mechanism for the swiveling of a swivel disk relative to a fixed disk. During the swiveling, the swivel disk is displaced eccentrically along at least a substantially circular path relative to the fixed disk. Preferably, in so doing, the central axis of the swivel disk moves circularly around the central axis of the fixed disk. The central axis of the fixed disk can be perpendicular to the fixed base. It can extend through the center of the fixed disk and / or the center of the fixed scroll. In particular, the center of the fixed scroll can form the center of the fixed disk and vice versa.

[0033] During operation (compressor operation), at least one compression space is formed between the swivel scroll and the fixed scroll. The fluid sucked in is trapped within the compression space, compressed within the compression space, moves in the direction of the outlet opening of the fixed disk, and is finally pushed into this outlet opening.

[0034] The suction region of the compressor channel consists of all regions of the compressor channel that are at least temporarily in direct fluid communication with the inlet of the compression section when the swivel disk swivels along the compression direction relative to the fixed disk. The discharge region of the compressor channel consists of all regions of the compressor channel that are at least temporarily in direct fluid communication with the outlet of the compression section when the swivel disk swivels along the compression direction relative to the fixed disk. The central region of the compressor channel consists of all regions of the compressor channel that cannot be in direct fluid communication with either the inlet of the compression section or the outlet of the compression section. These definitions apply to both the compressor channel of the fixed disk and the compressor channel of the swivel disk.

[0035] In the sense of the present application, the innermost winding or first winding of each scroll indicates the region of the scroll that extends from its inner end to the point wound once around its center.

[0036] An angular position of 0° is assigned to the inner end of the stationary scroll. The angular position increases continuously along the extension of the stationary scroll up to the outer end of the stationary scroll. The spiral angle of the stationary scroll is given by its outer end. Thus, the spiral angle corresponds to the maximum angular position of the stationary scroll.

[0037] This is illustratively explained for a stationary scroll having two windings: The first winding of the stationary scroll starts at an angular position of 0° at the inner end of the stationary scroll and ends at an angular position of 360°. The second and outermost winding starts at an angular position of 360° and ends at a spiral angle of 720° at the outer end of the stationary scroll.

[0038] Correspondingly, the angular position within the compressor channel is defined. The outer end of the spiral compressor channel is defined by the inlet opening of the compressor channel formed between the outer end of the stationary scroll and the starting point inside the outermost winding of the stationary scroll.

[0039] In the context of the present application, the outside of each scroll region is the side facing away from the center of the scroll in the radial direction of this region of the scroll. Correspondingly, the inside of this region of the scroll is the side facing the center of the scroll in the radial direction of this region of the scroll.

[0040] The compression section can form a compression space led inward and a compression space led outward. The compression space led inward is formed outside the stationary scroll and led along it. The compression space led outward is formed outside the stationary scroll and led along it.

[0041] At this point, it is emphasized that the definition of the compressor channel is independent of the definition of the compression space. In particular, the compression space does not always have to be completely within the compressor channel of the fixed disk. For example, the compression space can be formed by the outer end of the orbiting scroll contacting the outer surface of the outermost wrap of the fixed scroll. By this seal, the compression space led inward is closed and sealed. The newly formed compression space led inward can still be (partially) outside the compressor channel of the fixed disk at this point. On the other hand, the compression space led outward is closed by the outer surface of the orbiting scroll contacting the outer end of the fixed scroll. The newly formed compression space led outward is already completely inside the compressor channel at this point. It is guided by the outer surface of the compressor channel. In other words, the outer surface of the compressor channel is formed by the inner surface of the fixed scroll.

[0042] During operation, the suction pressure acts on the inlet of the compression section, and the outlet of the compression section is dominated by the discharge pressure. Preferably, the suction pressure during operation is in the range of 1 bar to 7 bar. Alternatively or additionally, the discharge pressure during operation is in the range of 8 bar to 32 bar. The exact suction pressure and the exact discharge pressure can vary depending on the fluid used and the exact operating conditions.

[0043] The suction pressure and the discharge pressure can be determined by a system through which the fluid compressed in the scroll compressor flows during operation. Such a system can be, for example, a heat exchanger in an air conditioning system.

[0044] The maximum discharge pressure of a scroll compressor results from the geometry of the compression section and the respective suction pressure. Further, the dead volume of the outlet opening (outlet bore) of the fixed disk can influence the maximum discharge pressure. The higher the suction pressure, the higher the maximum discharge pressure. At a given suction pressure, the maximum discharge pressure results from the compression of the fluid achievable due to the geometry in the compression section, based on known fluid equations, such as the ideal gas equation or the van der Waals equation. The (actual) discharge pressure is usually lower than the maximum discharge pressure.

[0045] The inlet of the compression section can include a plurality of partial regions. In particular, the inlet can comprise a first inlet partial region that supplies fluid to the compression space guided radially inward and a second inlet partial region that supplies fluid to the compression space guided radially outward. The partial regions can be spatially separated from each other, for example, on two opposite sides in the radially outer region of the compression section.

[0046] Direct oil return contributes to the direct return of oil directly into the compression section from the oil separator. The direct oil return extends directly from the oil separator into the compression section.

[0047] During operation, the oil is pushed into the direct oil return by the pressure from the oil separator. This oil flows through the direct oil return along the oil flow direction and exits into the compression section from the orifice opening of the direct oil return. The oil returned in such a way contributes to the lubrication of the compression section.

[0048] In a preferred embodiment of the invention, the orifice opening (of the direct oil return) is arranged in the inlet region of the compression section, which is in direct fluid communication with the inlet of the compression section, at least temporarily, during operation. Thereby, particularly good lubrication is ensured also in the radially outer regions of the orbiting scroll and the fixed scroll.

[0049] Depending on the exact positioning of the orifice opening, for example, during operation, the orifice opening may be temporarily scanned and covered by the swivel scroll. At this point, the orifice opening is not in direct fluid communication with the inlet. It is also possible that the orifice opening is in direct fluid communication with the inlet during a first period, scanned by the swivel scroll during a second period, in communication with the compression space during a third period, and scanned again by the swivel scroll during a fourth period during a complete rotation of the swivel disk.

[0050] In a particularly preferred embodiment, the orifice opening is not scanned by the compression space (or any of the plurality of compression spaces) at any time.

[0051] Alternatively or additionally, the orifice opening is scanned by the swivel scroll, particularly preferably exactly once, during a complete rotation of the swivel scroll.

[0052] The orifice opening for direct oil return is preferably arranged in the fixed disk. This reduces complexity and simplifies the manufacture of direct oil return. In particular, the orifice opening can be arranged completely within the fixed base. Alternatively, the orifice opening can be arranged completely or partially on the inner or outer surface of the fixed scroll. Such a variant is more difficult to manufacture. Instead, thereby, the lubrication of the inner or outer surface of the fixed scroll can be further improved.

[0053] In a particularly preferred embodiment, the orifice opening for direct oil return is arranged in the suction region of the compressor channel (of the fixed scroll) that is in direct fluid communication with the inlet of the compression section, at least temporarily during operation, and / or is arranged outside the compressor channel. When the orifice opening is arranged at the outer end of the compressor channel, a first partial region of the orifice opening can be arranged within the compressor channel and a second partial region of the orifice opening can be arranged outside the compressor channel.

[0054] According to another aspect, the direct oil return orifice opening is preferably arranged at a position angle in the range of γ - 30° to γ + 30°, where γ is the position angle of the outer end of the compressor channel. The orifice opening, in this case, is further arranged at a radial distance R from the center of the fixed disk M,1 and can be arranged at, R M,1 where R I (γ) - B K ) to R I (γ), and R I (γ) is the radial distance inside the fixed scroll at the outer end of the compressor channel (i.e., the outer end of the fixed scroll), and B K is the radial width of the compressor channel at the outer end of the compressor channel. Thus, in this case, the orifice opening is arranged near the outer end (upstream end) of the compressor channel. The orifice opening is, in that case, scanned at least once during one rotation by the end face of the orbiting scroll. Thereby, the oil flowing out from the orifice opening is particularly well distributed. In particular, R M,1 is in the range of (R I (γ) - B K / 2) to RR I (γ). The orifice opening embodied in this way contributes particularly well to lubrication in the region of the compression space led to the outside.

[0055] Alternatively, the direct oil return orifice opening is preferably arranged at a position angle in the range of θ - 30° to θ + 30° outside the fixed scroll, where θ = γ + 180°. The orifice opening, in this case, can also be arranged at a radial distance R from the center of the fixed disk M,2 and R M,2 is in the range of R A (θ - 360°) to R A (θ - 360°) + B K and R A(θ - 360°) is the radial distance outside the fixed scroll at the angular position θ - 360°. Thus, in this embodiment, the orifice opening is arranged outside the fixed scroll, at a position facing the outer end of the compressor channel with respect to the center of the fixed scroll. Thereby, the oil flowing out from the orifice opening is particularly well distributed. In particular, R M,2 is R A (θ - 360°) to R A (θ - 360°) + B K / 2 can be in the range. The orifice opening embodied in this way contributes particularly well to lubrication in the region of the compression space led inward.

[0056] Particularly preferably, a plurality of orifice openings are formed, and at least one of the plurality of orifice openings is formed according to one of the embodiments in the second - last aspect, and at least one of the plurality of orifice openings is formed according to one of the embodiments in the last - described aspect. The advantages are applied correspondingly to each.

[0057] In an advantageous embodiment of the present invention, the direct oil return includes a first flow rate valve. The first flow rate valve is preferably arranged between the first oil inlet of the direct oil return and the orifice opening (seen along the flow direction of the oil in the direct oil return). However, generally, the first flow rate valve can also be arranged directly at the first oil inlet or the orifice opening. The first flow rate valve can be formed particularly by the first oil inlet and / or the second orifice opening itself. The first flow rate valve reduces the mass flow rate of the oil (optionally accompanied by the fluid dissolved therein) returned through the direct oil return.

[0058] Particularly preferably, the first flow rate valve is embodied as a throttle valve.

[0059] In this application, the throttle valve should preferably be understood as an element that generates a pressure difference between the inlet and the outlet of the valve. Particularly preferably, it can be a non-adjustable throttle valve. It can be, for example, an orifice or a nozzle. This enables a simple, inexpensive and reliable implementation.

[0060] The first flow valve is adjusted to reduce the mass flow rate of the oil (optionally with the fluid dissolved therein) from the oil separator. In this way, the pressure of the direct oil return downstream of the first flow valve (for example, the intermediate pressure described below and / or the orifice pressure described below) can be easily affected.

[0061] In a particularly preferred embodiment, the direct oil return includes the first flow valve and a degassing chamber, and the degassing chamber is arranged between the first flow valve and the orifice opening of the direct oil return (seen along the intended flow direction of the oil in the direct oil return). In other words, the degassing chamber is arranged downstream of the first flow valve and upstream of the orifice opening.

[0062] During operation, the direct oil return continuously extracts oil from the oil separator and stores the excess oil in the degassing chamber. The degassing chamber is in the scroll compressor. By continuously extracting oil from the oil separator, for example, from the bottom or near the bottom of the oil separator, and actively intermediate storing the oil, the efficiency of the separation process is maximized. The amount of oil exiting the compressor and entering the external refrigerant circuit is reduced to a minimum.

[0063] As described above, especially at a particularly low rotational speed, since the mass flow rate of the refrigerant is small, there is a high risk that the oil discharged from the scroll compressor to the outer portion of the refrigerant circuit will inadvertently remain in the outer portion of the refrigerant circuit. Even in such a case, the oil from the degassing chamber ensures the oil supply to the scroll compressor until the system is balanced again. Then, when the operating point is changed to a high load point, the oil previously trapped in the outer portion of the refrigerant circuit is returned to the scroll compressor again by the high mass flow rate of the refrigerant, and is recovered and intermediate-stored in the scroll compressor again. Thereby, the system is automatically adjusted: accommodating or discharging oil as needed.

[0064] During operation, the oil separator receives (at least substantially) the discharge pressure. Thereby, the solubility of the fluid in the liquid oil in the oil separator increases. The first flow valve reduces the mass flow rate of the oil (optionally with the fluid dissolved therein) from the oil separator. This helps to adjust the intermediate pressure in the degassing chamber to a value lower than the discharge pressure. Thereby, the solubility of the fluid in the oil also decreases. Downstream of the first flow valve, the oil can become supersaturated with the fluid. In the degassing chamber, the supersaturated portion of the fluid in the oil can be separated from the oil in a (at least partially) controlled manner. This reduces the risk of uncontrolled formation of bubbles of the fluid in the oil downstream of the degassing chamber. If the supersaturated portion of the fluid is completely separated from the oil, at most, the same amount of fluid as the amount (the saturated portion of the fluid in the oil) that can be dissolved in the oil in the equilibrium state under given conditions is present in the oil.

[0065] A first fluid communication portion for direct oil return leads from the oil separator to the degassing chamber. The first flow valve can be arranged in this first fluid communication portion. A second fluid communication portion for direct oil return leads from the degassing chamber to the orifice opening.

[0066] Preferably, the scroll compressor is adjusted such that during operation, the intermediate pressure in the degassing chamber is in the range of 0.2 bar to 0.6 bar higher than the suction pressure (of the compression section or the scroll compressor), and very preferably in the range of 0.3 bar to 5 bar higher than the suction pressure. The exact intermediate pressure can be influenced, for example, by the first throttle valve and / or the fluid return described below.

[0067] Thereby, it is ensured that sufficient oil flows out from the orifice opening of the direct oil return. Further, it is ensured that fluid does not flow through the direct oil return against the oil flow direction in the direct oil return. If the pressure drop between the intermediate pressure and the suction pressure is too high, there may be too much oil flowing from the degassing chamber into the compression section.

[0068] Alternatively or additionally, the scroll compressor is preferably adjusted such that during operation, the intermediate pressure in the degassing chamber is at least 106% of the suction pressure.

[0069] At this time, the absolute value of the suction pressure can be different for different operating states. Also, the absolute value of the intermediate pressure can be different for different operating states. The ratio between the intermediate pressure and the suction pressure can also be different for different operating states. However, the ratio for all (given) operating states should be at least 1.06.

[0070] Particularly preferably, the degassing chamber is in the range of 30 cm 3 to 150 cm 3 and very preferably in the range of 50 cm 3 to 90 cm 3 in volume. Thereby, the oil remains in the degassing chamber for a long enough time on average so that at least a significant portion of the supersaturated portion of the fluid evaporates. On the other hand, the intermediate chamber requires little space and is compact enough to be easily integrated.

[0071] In a highly preferred development form, the direct oil return includes a second flow valve arranged behind the degassing chamber (seen along the oil flow direction in the direct oil return). In particular, the second flow valve can be arranged within the second fluid communication part, that is, downstream of the degassing chamber of the direct oil return and upstream of the orifice opening. In particular, the second flow valve can be designed as a throttle valve. As already defined previously, the throttle valve can be, for example, an orifice or a nozzle. The second flow valve can be integrally formed together with the orifice opening and / or the oil inlet of the second fluid communication part of the degassing chamber. The second flow valve contributes to restricting the mass flow rate of the oil from the degassing chamber. Thereby, the orifice pressure of the oil at the orifice opening can be easily and surely affected.

[0072] If the direct oil return has a plurality of orifice openings, the direct oil return preferably branches downstream of the degassing chamber (with respect to the oil flow direction in the direct oil return). Thus, only one degassing chamber is required for a plurality of orifice openings. This simplifies the structure and manufacture of the scroll compressor and reduces its cost. It is also possible for a plurality of second fluid communication parts to lead directly from the degassing chamber.

[0073] It is extremely advantageous if the direct oil return (or the second fluid communication part) branches downstream of the second flow valve. Thus, only one common second flow valve is required for a plurality of orifice openings of the same direct oil return. Thereby, the structural and manufacturing costs are further reduced. Furthermore, the same (at least substantially) orifice pressure acts on the plurality of orifice openings.

[0074] Alternatively, different second flow valves can be provided for different orifice openings among the plurality of orifice openings. Thus, the orifice opening pressures can be adjusted to be different for different orifice openings.

[0075] In a particularly preferred embodiment, the scroll compressor comprises a fluid return of fluid from the degassing chamber into the compression section. In this way, the fluid separated from the oil in the degassing chamber can be returned into the fluid circuit.

[0076] Most preferably, the orifice opening of the fluid return is arranged in the compressor channel of the fixed disk. The orifice opening can be formed, for example, as a hole in the fixed base. At least some regions of the fluid return can be formed in the fixed disk. This reduces complexity and manufacturing costs.

[0077] Most preferably, the orifice opening of the fluid return is arranged in the intermediate region of the compressor channel (of the fixed disk). Thereby, it is ensured that the fluid from the orifice opening of the fluid return cannot flow out upstream from the inlet of the compression section. At the same time, it is ensured that the orifice opening of the fluid return is not in direct fluid communication with the outlet opening of the fixed scroll. This guarantees the high efficiency and effectiveness of the scroll compressor.

[0078] The fluid return can comprise a check valve. The check valve prevents the fluid from flowing from the compression space scanning the orifice opening of the fluid return into the degassing chamber. Alternatively or additionally, the fluid return can comprise a flow valve. This makes it easier to adjust the intermediate pressure in the degassing chamber to be deliberately higher than the average value of the pressure of the fluid (in the compressor channel) at the orifice opening of the fluid return.

[0079] In other embodiments, the fluid can flow (at least substantially) freely between the degassing chamber and the orifice opening of the second fluid communication section. That is, the second fluid return does not comprise a check valve nor a flow valve. In that case, the intermediate pressure in the suction chamber is particularly directly affected by the time average value of the fluid at the orifice opening of the fluid return.

[0080] According to a further aspect, the fluid return orifice opening is, very preferably, located at a position within the compressor channel such that the time-averaged value of the pressure of the fluid within the compressor channel during operation is in the range of 104% to 170% of the suction pressure, and in an advanced form, in the range of 105% to 150%.

[0081] In an idealized view, when ignoring the mass flow of the returned oil and fluid, the intermediate pressure within the degassing chamber is exactly the time-averaged value of the pressure of the fluid at the fluid return orifice opening. In reality, the intermediate pressure during operation exceeds the time-averaged value of the pressure of the fluid at the fluid return orifice opening due to the mass flow rate of the returned oil and fluid. Due to this pressure difference, the fluid flows from the degassing chamber through the fluid return into the compression section. The pressure difference is maintained by supplying new oil from the oil separator into the degassing chamber together with the fluid dissolved therein. However, the intermediate pressure is critically affected by the time-averaged value of the pressure of the fluid at the fluid return orifice opening.

[0082] The ratio between the time-averaged value of the fluid at the fluid return orifice opening and the suction pressure substantially depends on the geometric shape of the compression section and the exact position of the fluid return orifice opening within the compressor channel. Also, it remains substantially constant for different operating conditions when the position of the orifice opening is given. On the other hand, the ratio can be targeted and controlled by shifting the position of the orifice opening. Therefore, the above-described embodiments are a particularly simple, reliable, and suitable approach for targeting and influencing the intermediate pressure for various operating conditions.

[0083] At this time, the absolute value of the suction pressure can be different for different operating conditions. Also, the absolute value of this time-averaged value can be different for different operating conditions. The ratio between the suction pressure and the time-averaged value of the pressure of the fluid at the fluid return orifice opening can also be different for different operating conditions. However, the ratio for all (given) operating conditions should be within the above-described range.

[0084] The above-described ratio setting results in an advantageous intermediate pressure in the degassing chamber, for example, according to one of the advantageous embodiments described elsewhere. The intermediate pressure is high enough that sufficient oil flows directly from the degassing chamber to the (at least one) orifice opening of the oil return and then out from there to reach the compression section. On the other hand, the intermediate pressure is low enough that not too much oil flows out of the degassing chamber and at least a substantial portion of the fluid dissolved in the oil supplied into the degassing chamber separates from the oil within the degassing chamber.

[0085] The calculation of the ratio of the time-averaged value of the pressure of the fluid (in the compressor channel) at the orifice opening to the suction pressure can be performed, for example, based on the calculation and / or measurement of the pressure averaged over one rotation of the fluid in the compressor channel at the position of the orifice opening at a given suction pressure. The calculation can also be performed based on the measurement and / or calculation of the compression ratio averaged over one rotation of the fluid in the compressor channel at the orifice opening of the fluid return.

[0086] The time range (or range of rotation angle) during which the orifice opening of the fluid return is closed by the orbiting scroll can be left out of consideration for the calculation of the time-averaged value of the pressure of the fluid at the orifice opening of the fluid return.

[0087] The absolute value of the suction pressure can be different for different operating states. The absolute value of this time-averaged value of the pressure of the fluid at the orifice opening of the fluid return can be different for different operating states. The ratio between the suction pressure and this time-averaged value can also be different for different operating states. However, the time-averaged value should be in the range of 104% to 170% of the above-described suction pressure in each operating state, and in the developed form, in the range of 105% to 150% for all (predetermined) operating states.

[0088] Very preferably, the orifice opening for fluid return is arranged outside the outlet region of the compressor channel. Thereby, it is ensured that the orifice opening for fluid return is not subjected to the discharge pressure by the fluid at any time. In one development form, the orifice opening is arranged in the compressor channel so as not to be in direct fluid communication with the compression space of the final stage at any time. Otherwise, an undesirably high intermediate pressure may occur in the degassing chamber.

[0089] According to a further aspect, the orifice opening for fluid return is very preferably arranged at a position angle ε in the compressor channel, where ε is in the range of γ - 300° to γ, and γ is the position angle of the outer end of the compressor channel.

[0090] Very preferably, the orifice opening for fluid return is arranged at a position angle ε1 in the compressor channel, where ε1 is in the range of γ - 300° to γ - 180°. The orifice opening can be arranged to be scanned only by the compression space directed outwards and to be closed exactly once per revolution by the orbiting scroll. For example, in this case, the sum of the distance of the orifice opening from the outside of the compressor channel at this position angle and the width of the orifice opening in the radial direction may be smaller than the width of the spiral arm of the orbiting scroll in the radial direction at the corresponding position angle of the orbiting scroll.

[0091] Alternatively, the orifice opening for fluid return is very preferably arranged at a position angle ε2 in the compressor channel, where ε2 is in the range of γ - 120° to γ. The orifice opening can be arranged to be scanned only by the compression space directed inwards and to be closed exactly once per revolution by the orbiting scroll. For example, in this case, the sum of the distance of the orifice opening from the inner surface of the compressor channel at this position angle and the width of the orifice opening in the radial direction may be smaller than the width of the spiral arm of the orbiting scroll in the radial direction at the corresponding position angle of the orbiting scroll.

[0092] Particularly preferably, the orifice opening for fluid return is arranged to be in direct fluid communication with the inlet of the compression section (suction pressure) for a swivel disk rotation angle of up to 130° to 360° per revolution. Alternatively or additionally, the orifice opening for fluid return is closed by a swivel scroll for a swivel disk rotation angle of up to, particularly preferably, 130° to 360° per revolution. Thereby, the temporally averaged pressure of the fluid and the intermediate pressure at the orifice opening for fluid return become high enough for good transport of oil from the degassing chamber into the compression section.

[0093] According to a further aspect, the scroll compressor is very preferably adjusted such that during operation, the intermediate pressure is at least 0.1 bar higher than the time-averaged value of the pressure of the fluid (in the compressor channel) at the orifice opening for fluid return. Due to the pressure difference, the fluid released in the degassing chamber flows back into the compression section through the fluid return.

[0094] Alternatively or additionally, the scroll compressor is very preferably adjusted such that during operation, the intermediate pressure is at least 2 bar higher than the time-averaged value of the pressure of the fluid (in the compressor channel) at the orifice opening for fluid return. When the intermediate pressure is very high, less of the fluid dissolved in the oil returns to the gas phase in the degassing chamber. In addition, an overly high intermediate pressure can lead to an excessive flow of oil directly from the degassing chamber to the orifice opening for oil return. It has already been described above that the intermediate pressure and the difference between the time-averaged value of the pressure of the fluid at the orifice opening for fluid return and the intermediate pressure can be easily and purposefully influenced by the exact positioning of this orifice opening.

[0095] For example, the intermediate pressure can be in the range of 0.2 bar to 1.5 bar higher than the time-averaged value of the pressure of the fluid (in the compressor channel) at the position of the orifice opening for fluid return during operation.

[0096] Most preferably, the fluid return inlet is disposed above the oil inlet of the second fluid communication part of the oil return directly within the degassing chamber. Thus, only the separated fluid flows into the fluid return, and correspondingly, the liquid oil flows directly into the second fluid communication part of the oil return. In this context, "above" means that when the scroll compressor is positioned in the desired operating position with respect to the direction of gravity, the fluid return inlet opens into the degassing chamber in front of (i.e., above) the oil inlet of the second fluid communication part of the oil return as seen along the direction of gravity. In particular, the fluid return inlet can be disposed at the upper end of the degassing chamber, and / or the inlet of the second fluid communication part of the oil return directly can be disposed at the lower end of the degassing chamber.

[0097] The desired operating position can be defined, for example, by the central axis of the fixed scroll being at least substantially perpendicular to the direction of gravity.

[0098] In a preferred embodiment, the scroll compressor comprises a discharge pressure chamber, and the oil separator is in direct fluid communication with the outlet of the compression section via the discharge pressure chamber. The discharge pressure chamber is in direct fluid communication with the compression section. The oil separator is in direct fluid communication with the discharge pressure chamber and thus, via the discharge pressure chamber, is in direct fluid communication with the outlet of the compression section. The discharge pressure chamber functions as a buffer chamber for the discharged fluid. It equalizes the discharge pressure.

[0099] In a particularly preferred development, the degassing chamber is formed radially outside the discharge pressure chamber and surrounds the discharge pressure chamber. The degassing chamber has a substantially hollow cylindrical basic shape, and the discharge pressure chamber is coaxially arranged in the center of the degassing chamber. This enables a very compact structure.

[0100] Preferably, the scroll compressor includes a contact pressure chamber on which a contact pressure acts during the compression operation, and the orbiting disk is pressed against the fixed disk by the contact pressure during operation.

[0101] The contact pressure chamber is disposed directly outside the oil return. The contact pressure chamber is not part of the direct oil return. The oil returned through the direct oil return is not led through the internal space of the contact pressure chamber that receives the contact pressure during operation. The direct oil return "bypasses" the internal space of the contact pressure chamber in a functional sense.

[0102] The direct oil return is formed in a spatially separated manner from the contact pressure chamber. It is separate from the contact pressure chamber.

[0103] In particular, the degassing chamber is formed, in some cases, in addition to the contact pressure chamber, i.e., separately. For example, the contact pressure chamber can be arranged on the side of the orbiting disk opposite the orbiting disk when viewed parallel to the central axis. In contrast, the degassing chamber can be arranged on the side of the fixed disk opposite the orbiting disk when viewed parallel to the central axis.

[0104] Particularly preferably, the scroll compressor includes a second oil return for returning oil from the oil separator into the contact pressure chamber.

[0105] The second oil return is used to supply oil to the contact pressure chamber. The second oil return can be used to apply pressure to the contact pressure chamber. The rear surface of the orbiting disk facing away from the fixed disk can form part of the boundary of the contact pressure chamber. Preferably, the second oil return leads directly from the oil separator to the contact pressure chamber. This results in a slight complexity and the fact that the scroll compressor can be manufactured easily and inexpensively.

[0106] In a highly advantageous embodiment of the present invention, the second oil return is provided with a flow valve. The flow valve affects the operation of the second oil return. In particular, it affects the amount of oil flowing into the contact pressure chamber through the second oil return. Thereby, the flow valve assists in the adjustment and setting of the exact contact pressure in the contact pressure chamber.

[0107] Particularly preferably, the flow valve of the second oil return is embodied as a throttle valve. In this way, the adjustment of the contact pressure is much facilitated by the second oil return (and, optionally, the reference return communication, see below). This increases the efficiency of the scroll compressor as compared to a design without a throttle valve in the second oil return.

[0108] The second oil return is at least partially formed separately from the direct oil return (first oil return). The second oil return and the direct oil return may have a common starting region. In this case, the direct oil return branches off from the second oil return, and the branch is in front of the contact pressure chamber when viewed along the second oil return (in the direction of oil flow). Particularly preferably, the branch is in front of the flow valve of the second oil return when viewed along the second oil return (in the direction of oil flow). The common starting region begins with a common oil inlet opening into the oil separator.

[0109] In a highly preferred embodiment of the present invention, the direct oil return comprises a first oil inlet opening into the oil separator, and the second oil return comprises a second oil inlet opening into the oil separator. The second oil inlet is different from the first oil inlet. The second oil inlet is formed separately from the first oil inlet. In particular, the second oil inlet may be formed spatially separated from the first oil inlet.

[0110] In one development form, the second oil return is prioritized over the direct oil return in case of oil shortage. When the amount of liquid oil in the oil separator falls below a predetermined value, the oil flow through the direct oil return is reduced relative to the oil flow through the second oil return and / or the oil flow through the direct oil return is completely stopped.

[0111] In this state, little or no oil is introduced into the compression section through the direct oil return. As a result, the friction in the compression section increases and the efficiency decreases. However, the contact pressure chamber continues to be supplied with oil. The temporarily limited lack of lubrication can be temporarily compensated for by the oil in the degassing chamber. Thus, the swivel disk is further lubricated at least from its rear side. Further, in some cases, the part of the swivel mechanism in the contact pressure chamber is further lubricated. Further, the contact pressure in the contact pressure chamber can be more easily maintained. In this way, the scroll compressor continues to be at least functional. Some lubrication of the compression section can be maintained, for example, by oil passing from the contact pressure chamber through the swivel disk into the compression section, by oil flowing from the contact pressure chamber into the compression section through the reference communication part described below, and / or by the oil entrained by the inhaled fluid.

[0112] In a highly preferred embodiment, the first oil inlet is arranged above the second oil inlet. In this context, "above" means that when the scroll compressor is positioned in the desired operating position relative to the direction of gravity, the first oil inlet is in front of (i.e., above) the second oil inlet when viewed along the direction of gravity and opens into the oil separator. In other words, the first oil inlet opens above the second oil inlet within the oil separator. In particular, the second oil inlet can be arranged at the lower end of the oil reservoir in the oil separator. When the oil level inside the oil separator drops from the normal level, in such an arrangement, initially only the first oil inlet dries out.

[0113] Alternatively or additionally, the scroll compressor may comprise a valve mechanism that automatically reduces or stops the oil flow through the direct oil return when the amount of liquid oil in the oil separator falls below a predetermined value. The valve mechanism may comprise one or more valves. When the second oil return and the direct oil return have a common starting region, for example, a flow dividing valve may be formed at the branch of the direct oil return from the second oil return. The valve mechanism may comprise a level sensor that detects when the amount of liquid oil in the oil separator falls below a predetermined value.

[0114] Alternatively or additionally, the direct oil return is very preferably formed completely separately from the second oil return. This means that the direct oil return does not open directly (and vice versa) into the second oil return at any point. In particular, in this case, they do not have a common starting region. The second oil return and the direct oil return are not directly fluidly connected in this sense. This of course does not exclude the fact that the first oil inlet of the direct oil return and the second oil inlet of the second oil return are directly (but indirectly) fluidly connected to each other via the internal space of the heat exchanger.

[0115] Very preferably, the scroll compressor comprises a reference opening arranged in the compression section and a reference communication section that forms a fluid communication between the contact pressure chamber and the reference opening. The reference communication section may be designed to influence the contact pressure based on the reference pressure acting on the reference opening during operation.

[0116] The reference opening may be formed in the orbiting base within the compressor channel of the orbiting disk or in the fixed base within the compressor channel of the fixed disk.

[0117] Very preferably, the reference opening is formed in the orbiting base within the compressor channel of the orbiting disk and the reference communication section extends through the orbiting disk. Thus, the reference communication section can be implemented very simply and inexpensively.

[0118] The contact pressure is directly affected by the reference pressure. The reference pressure strongly depends on the given position of the reference opening in the compressor channel, and here also on the suction pressure and possibly the discharge pressure. In that regard, the difference between the contact pressure and the suction pressure automatically adapts to the operating state of the scroll compressor. Therefore, no laborious, external, failure-prone, and expensive control of the contact pressure is required. In particular, no actively adjustable pressure control valve is required for setting and controlling the contact pressure. Due to the interaction between the reference return connection and the reference opening, a pressure equilibrium is established in the contact pressure chamber. Through the design and adjustment that define the purpose of the reference return connection and the reference opening, especially the precise positioning of the reference opening in the corresponding compressor channel, an automatic setting of different desired contact pressures for various operating states of the scroll compressor is achieved. Accordingly, the contact force that presses the orbiting disk against the fixed disk by the contact pressure is adjusted to the separating force acting on the orbiting disk in each operating state for various operating states. This improves the efficiency and reliability of the scroll compressor.

[0119] The reference connection may include a flow valve. In particular, the flow valve can be designed as a non-adjustable throttle valve. Thereby, it can further affect the contact pressure. The flow valve can also help to ensure that the pressure difference during one rotation of the orbiting disk does not act on the contact pressure chamber without attenuation.

[0120] Highly preferably, through the reference connection, oil is guided from the contact pressure chamber between the fixed disk and the orbiting disk. In this case, the scroll compressor has, in addition to a direct oil return, an "indirect oil return", and the indirect oil return returns the oil from the oil separator only indirectly through the internal space of the contact pressure chamber into the compression section. The indirect oil return includes a second oil return and a reference connection. Such an indirect oil return is of course not a direct oil return in the sense of the present disclosure.

[0121] In a highly preferred embodiment of the present invention, the scroll compressor has two compression spaces, and the reference opening is arranged in the compressor channel (of the fixed disk or the orbiting disk) such that, during the compression operation, for the first part of the time required for one rotation of the orbiting disk, it is in direct fluid communication with the final-stage compression space, and for the second part of the time required for one rotation, it is in direct fluid communication with the second-stage compression space from the final stage. At this time, it is not necessary for the sum of the first part and the further part to result in the entire time required for rotation. Rather, there may be still other parts.

[0122] By this positioning that determines the purpose of the reference opening, the high-pressure region of the scroll compressor also affects the contact pressure, ensuring that the contact pressure during the compression operation is always set sufficiently high in all operating states. As a result, the contact force acting on the orbiting disk is sufficiently greater than the separating force. The orbiting disk is thereby pressed airtight against the fixed disk in all operating states during the compression operation.

[0123] The final-stage compression space is characterized in that the fluid therein is at least partially guided into the outlet opening during this rotation of the orbiting disk during the compression operation. The second-stage compression space from the final stage is characterized in that the fluid therein is at least partially guided into the outlet opening during the next rotation of the orbiting disk during the compression operation.

[0124] For further explanations, details and design options regarding the reference return communication and the reference opening, especially the reference opening in the compressor channel of the fixed disk, reference should be made to German Patent Application Publication No. 102017125968 and International Publication No. 2019 / 092024. The disclosure contained therein is applied mutatis mutandis to the reference opening in the compressor channel of the orbiting disk as appropriate.

[0125] The scroll compressor may include a suction pressure chamber that is in fluid communication with the inlet of the compression section. In particular, the suction pressure chamber may be in direct fluid communication with the inlet of the compression section. The suction pressure acts on the suction pressure chamber during operation.

[0126] The scroll compressor may include an inlet port. The inlet port may be in direct fluid communication with the inlet of the compression section via an inlet pressure chamber.

[0127] The scroll compressor may include a discharge port. The discharge port may be in fluid communication with an oil separator. Preferably, an oil separator outlet opening for the fluid within the oil separator that is in direct fluid communication with the discharge port is disposed directly above the first oil inlet of the oil return (and, optionally, the second oil inlet of the second oil return). In this context, "above" means that when the scroll compressor is positioned in the desired operating position with respect to the direction of gravity, the oil separator outlet opening within the oil separator is disposed in front of (i.e., above) the first oil inlet when viewed along the direction of gravity.

[0128] In a development of the present invention, the outlet of the compression section includes a check device. It may include, for example, a check flap and / or a check valve. The check device prevents the compressed fluid from flowing back through the outlet of the compression section (in a direction opposite to the desired flow direction). Otherwise, if the discharge pressure within the discharge pressure chamber is higher than the pressure at the center of the fixed scroll, the fluid may flow back from the discharge pressure chamber through the outlet of the compression section.

[0129] The check device may form the (downstream) end of the compression section (functionally and / or spatially).

[0130] Since the check device is part of the outlet of the compression section, the oil separator is in fluid communication with the outlet of the compression section even when the check device is closed. When a discharge pressure chamber is formed between the outlet of the compression section and the oil separator, correspondingly, the discharge pressure chamber in the sense of the present application is in direct fluid communication with the outlet of the compression section even when the check device is closed.

[0131] Particularly preferably, the discharge pressure chamber, the contact pressure chamber, the swivel disk, the fixed disk, the return communication portion, and the reference return communication portion are arranged within the suction pressure chamber. Thereby, all of these components are reliably surrounded by the suction pressure chamber. In this case, the suction port and the discharge port can be arranged in the suction pressure chamber, and the discharge port is in fluid communication with the oil separator in a pressure-resistant manner.

[0132] In an advanced form of the present invention, the fixed scroll has at least 1.25 windings. This corresponds to a spiral angle of the fixed scroll of at least 450°. Thereby, sufficient maximum compression of the scroll compressor is ensured for normal applications.

[0133] Alternatively and / or additionally, the fixed scroll preferably has a maximum of 2.5 windings. This corresponds to a spiral angle of the fixed scroll of a maximum of 900°. Even in that case, the scroll compressor can still be compact, lightweight, and manufactured inexpensively.

[0134] Particularly preferably, the fixed scroll has 2 windings, and the reference opening (to the contact pressure chamber) within the compressor channel is arranged at a position angle of at least 315°, at most 435°, very preferably at least 345°, at most 405° from the inner end of the fixed scroll. This arrangement has been demonstrated to be particularly practical.

[0135] When the second return communication portion is provided with a plurality of orifice openings and / or at least one orifice opening is provided in each of the plurality of second return communication portions, the individual orifice openings can be embodied independently of each other according to any of the foregoing embodiments and modifications. The advantages are correspondingly applicable. Thus, for example, it is possible that all the orifice openings are embodied in the same way, a first portion of all the orifice openings is formed according to the first embodiment, a second portion of all the orifice openings is embodied according to the second embodiment, or all the orifice openings are embodied in different manners.

[0136] Preferably, the scroll compressor comprises an electric motor for driving the orbiting disk. Incorporating the electric motor into the scroll compressor enables particularly accurate and efficient operation of the scroll compressor. The operation of the electric motor can be precisely adjusted for a specific scroll compressor. In particular, the drive of the scroll compressor is, in that case, independent of the operating state of other external units. Most preferably, the electric motor is arranged inside the suction chamber. In a particularly preferred development, the scroll compressor is an electric scroll compressor integrated with an inverter.

[0137] Alternatively and / or additionally, the scroll compressor can also be provided with a power transmission device for driving the orbiting disk by an external drive unit. The external drive unit can be, for example, an internal combustion engine. The power transmission device can be provided with a clutch (such as a magnetic clutch).

[0138] Optionally, the scroll compressor can also be used, for example, in a heat pump system. This is particularly interesting for the air conditioning of electric vehicles and / or full hybrid vehicles.

[0139] The present invention further relates to an air conditioning system comprising a scroll compressor according to the present invention. In particular, it can be an air conditioning system for a vehicle with a prime mover.

[0140] The design options and advantages described for the scroll compressor apply correspondingly to the system.

[0141] The present invention will be described below based on examples with reference to the drawings. In this case, all features described and / or illustrated, alone or in any combination, form the subject matter of the present invention regardless of their summary in the claims or their backward references.

Brief Description of the Drawings

[0142]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0143] FIG. 1 schematically shows a longitudinal section of a first embodiment according to the present invention of a scroll compressor 1 for compressing a fluid. The fluid is, for example, a refrigerant or a refrigerant mixture in a refrigerant circuit.

[0144] The scroll compressor 1 includes a compression section 10 having an inlet 11, a fixed disk 20, a swivel disk 30, and an outlet 12. A discharge pressure chamber 40 is directly connected to the outlet 12. In this embodiment, the outlet 12 includes a check device 13 that prevents backflow of the compressed refrigerant from the discharge pressure chamber 40 into the compression section 10. The check device 13 is illustrated here exemplarily as a check valve and forms the downstream end of the compression section 10.

[0145] Viewed along the flow direction of the (operating) refrigerant, an oil separator 45 is directly connected to the discharge pressure chamber 40. Thus, the oil separator 45 is in direct fluid communication with the discharge pressure chamber 40 and is in direct fluid communication with the outlet 12 of the compression section 10 (via the discharge pressure chamber 40).

[0146] The scroll compressor 1 includes a housing 90 having a suction port 91 and a discharge port 92.

[0147] The suction port 91 is in direct fluid communication with the inlet 11 of the compression section 10 via a suction pressure chamber 93. During operation, refrigerant is inhaled from an external refrigerant circuit via the suction port 91.

[0148] The discharge port 92 is in direct fluid communication with an oil separator outlet opening 46 of the oil separator 45. During operation, the compressed refrigerant is discharged into an external refrigerant circuit via the discharge port 92.

[0149] During operation, a suction pressure acts on the suction pressure chamber 93 and the inlet 11 of the compression section. The suction pressure can be, for example, in the range of 0.7 bar to 9 bar during operation. The discharge pressure chamber 40, the oil separator 45, and the discharge port 92 are dominated by a discharge pressure that is greater than the suction pressure during operation. The discharge pressure can be, for example, in the range of 6 bar to 32 bar. The suction pressure and the discharge pressure depend, inter alia, on the refrigerant used and the operating conditions of the external refrigerant circuit.

[0150] The suction pressure chamber 93 is only schematically shown in FIG. 1. Preferably, the suction pressure chamber 93 at least surrounds the contact pressure chamber 80 in a jacket-like manner. That is, the suction pressure chamber 93 extends completely around the contact pressure chamber 80 along the circumferential direction (with respect to the central axis). Alternatively or additionally, the suction pressure chamber 93 may surround at least a part of the compression section 10 in a jacket-like manner. That is, the suction pressure chamber 93 extends completely around the part of the compression section 10 described above along the circumferential direction (with respect to the central axis). The part of the compression section 10 described above may be opposite to the contact pressure chamber 80, especially when viewed along the central axis.

[0151] The suction pressure chamber 93 can be formed, for example, at least substantially in a cylindrical jacket-like shape around the contact pressure chamber 80 and / or at least a part of the compression section 10 on the side of the contact pressure chamber 80.

[0152] The fixed disk 20 faces the discharge pressure chamber 40, and the swivel disk 30 faces the contact pressure chamber 80.

[0153] The cutting plane of FIG. 3 is between the swivel disk 30 and the fixed disk 20 in FIG. 1 or FIG. 2 and extends parallel to the fixed base 22 of the fixed disk 20. On the fixed base 22, a fixed scroll 21 having 2.25 turns is arranged. Correspondingly, the outer end 25 of the fixed scroll 21 is arranged at a spiral angle of 810° from the inner end 24 of the fixed scroll 21.

[0154] FIG. 4 is a simplified illustration of a top view of the fixed disk 20.

[0155] For simplicity, the orbiting scroll 31 is shown, in FIG. 4, in a modified example having two windings. Correspondingly, the outer end 25 of the fixed scroll 21 is arranged at a spiral angle of 720° from the inner end 24 of the fixed scroll 21. In other respects, the structure and function of the fixed disk 20 in FIGS. 3 and 4 are the same, and the same reference numerals are used for the same elements.

[0156] Returning to FIG. 3, from the orbiting disk 30, only the orbiting scroll 31 arranged on the orbiting base 32 (not shown in FIG. 3, see FIG. 5) of the orbiting disk 30 can be seen because it is a cross-section. The orbiting scroll 31 has 2.25 windings (similar to the embodiment of the fixed scroll 21 in FIG. 3).

[0157] The fixed disk 20 and the orbiting disk 30 are arranged in combination with each other. In the (compression) operation, the orbiting disk 30 is pressed against the fixed disk 20 by the contact pressure in the contact pressure chamber 80 (see FIG. 1). Thereby, on the one hand, the end face of the orbiting scroll 31 facing away from the orbiting base 32 is airtightly adhered to the fixed base 22, and on the other hand, the end face of the fixed scroll 21 facing away from the fixed base 22 is airtightly adhered to the orbiting base 32.

[0158] The fixed base 22, the fixed scroll 21, the orbiting base 32 and the orbiting scroll 31 thereby define a plurality of compression spaces 14a, 14b, 14c.

[0159] At the position of the orbiting disk 30 or the orbiting scroll 31 shown in FIG. 3, the final-stage compression space 14c and the compression spaces 14a, 14b of the second stage from the final stage are defined in the compressor channel 26 formed during the winding of the fixed scroll 21. The final-stage compression space 14c includes two sub-areas that are in fluid communication with each other through a narrow gap (not visible in FIG. 3) between the fixed scroll 21 and the orbiting scroll 31.

[0160] A vector diagram is shown on the left side of FIG. 3, which indicates the rotation angle 103 of the swivel disk 30 (and thus the swivel scroll 31) and its rotation direction or compression direction 100. The swivel disk 30 starts a new rotation when its rotation position 103 in the vector diagram is exactly at the rotation angle 101 of 0°. Then, the outer surface of the swivel scroll 31 just contacts the outer end 25 of the fixed scroll 21, and at this time, the second-stage compression space 14b led to the outside is closed from the final stage. At the same time, the outer end 34 of the swivel scroll 31 contacts the outer surface of the outermost winding of the fixed scroll 21, and at this time, the second-stage compression space 14a led to the inside is closed from the final stage. In FIG. 3, starting from FIG. 3 where the swivel disk 30 has already moved further to the rotation position 103 of 45° along the compression direction 100 starting from the rotation angle 101 of 0°, the swivel disk 30 further rotates around the center of the fixed scroll 21 along the compression direction 100.

[0161] When the swivel disk 30 further rotates 270° along the compression direction 100 with respect to the fixed disk 20 starting from FIG. 3, it reaches the rotation position of 0°, and its current rotation ends. Most of the refrigerant that was in the compression space of the final stage 14c in FIG. 3 was led into the outlet opening 28 of the fixed base 22, and thus to the outlet 12 of the compression section 10. The outlet opening 28 is arranged at the center of the fixed disk 20 or the fixed scroll 21.

[0162] The scroll compressor 1 is provided with a direct oil return 50 for returning oil from the oil separator 45 into the compression section 10.

[0163] More precisely, the direct oil return 50 extends from the first oil inlet 51 in the oil separator 45 to the two orifice openings 59a, 59b of the fixed base 22 of the fixed disk 20. During operation, the direct oil return 50 injects the oil from the oil separator 45 directly from the orifice openings 59a, 59b between the fixed disk 20 and the swivel disk 30.

[0164] In the embodiment shown in FIG. 1, the direct oil return 50 includes, as viewed along the oil flow direction, a first oil inlet 51, a first fluid communication portion 52 having a first throttle valve 53, a degassing chamber 54, a second fluid communication portion 56 having a second throttle valve 57 and a branch portion 58, and further two orifice openings 59a, 59b.

[0165] During operation, the internal space of the oil separator 45 is governed by the discharge pressure. In the oil separator 45, the refrigerant rises and the liquid oil accumulates in the lower half of the oil separator 45. In this way, the refrigerant and the oil are separated from each other. In the liquid oil, due to the high discharge pressure, the solubility of the refrigerant increases, and the liquid oil contains a certain proportion of dissolved refrigerant.

[0166] The first oil inlet 51 is disposed in the lower half of the internal space of the oil separator 45, and the oil separator outlet opening is disposed at the upper end of the internal space of the oil separator 45. Due to the discharge pressure, the liquid oil is extruded from the oil separator 45 through the first oil inlet 51 into the first fluid communication portion 52.

[0167] In the first fluid communication portion 52 of the direct oil return 50, the oil flows through the first throttle valve 53. The first throttle valve 53 can be designed as a non-adjustable throttle valve. For example, the first throttle valve 53 can be embodied as an orifice opening or a nozzle. The first throttle valve 53 reduces the mass flow rate of the oil. Then, the oil further flows into the degassing chamber 54. Due to the influence of the mass flow rate of the oil, the intermediate pressure in the degassing chamber 54 can be affected. Due to the pressure drop, the solubility of the refrigerant in the oil decreases. The oil can be supersaturated with the refrigerant behind the first throttle valve 53. In the degassing chamber 54, the supersaturated portion of the refrigerant can evaporate. Liquid oil accumulates in the lower region of the degassing chamber 54, and refrigerant accumulates in the upper region of the degassing chamber 54. The degassing chamber 54 acts, so to speak, as an additional oil separator for the direct oil return 50 and the fluid return 70.

[0168] In the lower region of the degassing chamber 54, for example, in the bottom region of the degassing chamber 54, an oil inlet 55 of a second fluid communication portion 56 of the direct oil return 50 is arranged. Due to the intermediate pressure dominant in the degassing chamber 54, the liquid oil is pushed out from the degassing chamber 54 through the oil inlet 55 into the second fluid communication portion 56.

[0169] The second fluid communication portion 56 is provided with a second throttle valve 57 that restricts the mass flow rate of the oil exiting the degassing chamber. Thereby, it can be prevented that the intermediate pressure in the degassing chamber 54 undesirably drops strongly. The second throttle valve 57 can also be embodied as a non-adjustable throttle valve, for example, as an orifice opening or a nozzle.

[0170] Downstream of the second throttle valve 57, the second fluid communication portion 56 branches into two tributaries at a branch portion 58. The two tributaries at least partially penetrate the fixed disk 20. They each terminate at one of the orifice openings 59a, 59b arranged in the fixed base 22.

[0171] At this time, each of the orifice openings 59a, 59b is arranged in the inlet region of the compression section 10, which is in direct fluid communication with the inlet 11 of the compression section 10 at least partially during operation. Thereby, the oil flowing out from the orifice openings 59a, 59b is entrained by the inhaled refrigerant and then, together with the refrigerant, is enclosed in the newly formed compression space. Since the orifice openings 59a, 59b are respectively located in the inlet region of the compression section 10, the radially outer engagement regions of the fixed scroll 21 and the orbiting scroll 31 are also well lubricated.

[0172] Furthermore, all orifice openings 59a, 59b are each scanned by the orbiting scroll 31 at least once during each rotation of the orbiting disk 30. This results in good distribution of the supplied oil. The oil flowing out from the orifice openings 59a, 59b is applied to the orbiting scroll 31. It can be seen from FIG. 4 that, for example, the orifice opening 59a is scanned by the outer end portion 34 of the orbiting scroll 31 in each rotation.

[0173] Particularly preferred positions of the orifice openings 59a, 59b will be described in more detail below with reference to FIG. 4.

[0174] In the compression spaces 14a, 14b, 14c (see FIG. 3) formed in the compression section 10 between the fixed disk 20 and the orbiting disk 30, the refrigerant is transported to the center of the fixed scroll 21, and at that time, due to the decrease in the volume of the compression spaces 14a, 14b, 14c, it is compressed until the discharge pressure is reached. Subsequently, in this example, it is transported into the oil separator 45 through the outlet opening 28 at the center of the fixed disk 20 and the outlet 12 including the check valve 13, and the discharge pressure chamber 40.

[0175] At that time, oil is also transported together with the refrigerant and finally reaches the oil separator 45 again. There, it is separated from the refrigerant and can be directly used in the new cycle of the oil return 50. The refrigerant from which the oil has been removed, compressed, and reached the discharge pressure is led out of the scroll compressor 1 through the oil separator outlet opening 46 and the discharge port 92.

[0176] Here, based on FIG. 4, it will be explained where the orifice openings 59a, 59b of the direct oil return can preferably be arranged.

[0177] The angular position of 0° is defined by the inner end 24 of the fixed scroll 21. It should be noted that the end bead 24a of the inner end 24 is irrelevant to the determination of the angular position of 0°. Since the fixed scroll 21 in Fig. 4 has two windings, its outer end 25 is arranged at an angular position of 720° or helix angle. Correspondingly, the inlet opening of the compressor channel 26 that extends at an angular position of 360° between the outer end 25 and the starting point of the outer winding of the fixed scroll 21 is at the angular position of 720°.

[0178] Fig. 4 shows a preferred first region A for the arrangement of the orifice opening of the direct oil return 50. M,1 is shown.

[0179] In Fig. 4, γ is the angular position of the outer end 25 of the fixed scroll 21. Correspondingly, γ is also the angular position of the outer end of the compressor channel 26. At the angular position γ, the inner surface of the fixed scroll 21 has a distance R I (γ) in the radial direction from the center of the fixed scroll 21. At the same time, the inlet opening of the compressor channel 26 of the fixed disk 20 has a radial width B K at the angular position. Here, the width B K is K B I = R A (γ) - R A (γ - 360°) obtained as such. Here, R A (γ - 360°) is the distance of the outer surface of the fixed scroll 21 at the angular position corresponding to γ - 360°.

[0180] The first region A M,1 extends circumferentially from the angular position γ - 30° to the angular position γ + 30° and extends radially from R I (γ) - B K / 2 to R I (γ). This means that the first region A M,1 is arranged in the outer half in the radial direction of the compressor channel 26 at the inlet opening of the compressor channel 26, precisely in this angular position range or its virtual continuity.

[0181] In FIG. 4, the orifice opening 59a is in the first region A M,1 at, precisely, a position angle γ = 720°, in the vicinity of the outer surface of the compressor channel 26, i.e., at a radial distance R I (γ) - B K / 10. The orifice opening 59a is closed only once per revolution by the orbiting scroll 31. In the illustrated embodiment, the orifice opening 59a does not communicate directly with the compression space 14b that is led inward. The orifice opening 59a ensures lubrication of the outer compression space in a particularly advantageous manner. In FIG. 3, the compression space 14a is led outward.

[0182] FIG. 4 further shows a preferred second region A M,2 for the arrangement of the orifice opening of the direct oil return 50. In this example, the orifice opening 59b is arranged within the second region A M,2 .

[0183] The second region M,2 extends radially outside the fixed scroll 21 about the position angle θ, where θ = γ + 180°. The second region A M,2 extends circumferentially from the position angle θ - 30° to the position angle θ + 30° and radially from R A (θ - 360°) to R A (θ - 360°) + B K / 2. Thus, the second region A M,2 is outside the compressor channel 26 of the fixed disk 20, more precisely on the opposite side of the inlet opening of the compressor channel 26. At that time, R A (θ - 360°) is the radial distance of the outer surface of the fixed scroll 21 at the position angle θ - 360° = γ - 180°.

[0184] In FIG. 4, the orifice opening 59b is in the second region A M,2 at, precisely, a position angle γ = 900°, in the vicinity of the outer surface of the outermost winding of the fixed scroll 21, i.e., at a radial distance RA (θ) + B K It is arranged at / 10. The orifice opening 59b ensures the lubrication of the compressed space led to the inside in a particularly advantageous manner. In FIG. 3, the compressed space 14b is led to the inside.

[0185] In FIG. 3, the orifice openings 59a and 59b of the direct oil return 50 are arranged in the same manner as described with reference to FIG. 4.

[0186] The scroll compressor 1 further includes a fluid return 70 for returning the refrigerant from the degassing chamber 54 into the compression unit. The fluid inlet 71 of the fluid return 70 is arranged in the upper region of the degassing chamber 54. In this way, the liquid oil does not flow from the degassing chamber 54 into the fluid return 70.

[0187] The fluid return 70 extends through the fixed disk 20. The orifice opening 72a of the fluid return 70 is arranged in the compressor channel 26 of the fixed disk 20 (see FIGS. 3 and 5). Here, the orifice opening 72a is arranged in the inlet region of the compressor channel 26, but may also be scanned by the temporarily closed compressed space. In FIG. 3, the compressed space 14b from the second stage from the final stage is just scanning the orifice opening 72a. Therefore, the time-averaged value of the pressure of the refrigerant in the compressor channel 26 at the orifice opening 72a is higher than the suction pressure. In this embodiment, the intermediate pressure in the degassing chamber 54 during normal operation exceeds the time-averaged value of the pressure of the refrigerant in the compressor channel 26 at the position of the orifice opening 72a, and strictly speaking, is in the range of 0.2 bar to 1.5 bar according to the exact operating state. The pressure difference with respect to the discharge pressure pushes the liquid oil from the degassing chamber into the second fluid communication portion 56 and then from the orifice openings 59a and 59b of the direct oil return 50.

[0188] The intermediate pressure in the degassing chamber 54 is particularly affected by the following: - The discharge pressure and mass flow rate of the oil containing the entrained refrigerant flowing into the degassing chamber 54 through the first fluid communication portion 52 - The time-averaged values of the pressure at the orifice openings 59a and 59b and the corresponding mass flow rate of the oil exiting the degassing chamber 54 through the second fluid communication portion 56, and - The time-averaged values of the pressure of the refrigerant in the compressor channel 26 at the orifice opening 72a and the corresponding mass flow rate of the refrigerant exiting the degassing chamber 54 through the fluid return 70

[0189] The driving force is the discharge pressure in the oil separator 45.

[0190] The intermediate pressure (or the time-averaged value of the intermediate pressure when the operating state does not change) is, in this embodiment, in the range of 0.3 bar to 5 bar higher than the suction pressure during operation. When the suction pressure is 1 bar, the intermediate pressure during operation is at least 0.3 bar higher than the suction pressure, i.e., 1.3 bar in absolute value, and at most 0.9 bar higher, i.e., 1.9 bar in absolute value. When the suction pressure is 7 bar, the intermediate pressure during operation is at most 4.2 bar higher than the suction pressure, i.e., 11.2 bar. Of course, the intermediate pressure remains clearly below the discharge pressure of 32 bar in this case. When the suction pressure is 5 bar, the intermediate pressure during operation is in the range of 0.6 bar to 3.5 bar higher than the suction pressure. These values are examples. The exact intermediate pressure depends on the exact operating state, e.g., the discharge pressure. The exact pressure ratio may also depend on the refrigerant used.

[0191] In other words, the intermediate pressure during operation is in the range of 1.3 bar (minimum intermediate pressure) and 11.2 bar (maximum intermediate pressure).

[0192] Based on FIG. 7, the advantageous positions of the orifice openings 72a and 72b of the fluid return 70 will be described below.

[0193] Generally, the orifice openings 72a and 72b of the fluid return 70 in the compressor channel 26 are preferably ε min = γ - 300° and ε maxis arranged at the angular position (within the compressor channel 26) within the range of γ, where γ is the angular position of the outer end of the compressor channel.

[0194] Figure 7 shows two particularly preferred regions A M,3 and A M,4 for the arrangement of the orifice openings 72a, 72b of the fluid return 70 within the compressor channel 26.

[0195] One region A for the arrangement of the orifice opening 72a M,3 is defined by the orifice opening 72a of the fluid return 70 located therein being arranged at an angular position ε1 within the range of ε min = γ - 300° to ε max,1 = γ - 180°, and the orifice opening 72a is further arranged to be scanned only by the compressed space 14b led to the outside and to be scanned exactly once per rotation by the orbiting scroll 31. For example, the orifice opening 72a of the fluid return 70 in FIGS. 3, 4, and 7 is arranged at the angular position ε1 = γ - 248° within the compressor channel 26. The orifice opening 72a is further arranged at this angular position outside the compressor channel 26. Thereby, the orifice opening 72a is scanned only by the compressed space 14b led to the outside in this embodiment. The orifice opening 72a is not in direct fluid communication with any one of the compressed spaces 14a led to the inside at any point in time here.

[0196] More precisely, in this embodiment, the orifice opening 72a of the fluid return 70 is closed by the orbiting scroll 31 in the rotation angle range of 0° to 20°. When the rotation angle reaches 20°, the compressed space 14b led to the outside starts to scan the orifice opening 72a. In the rotation angle range of 20° to 270°, the orifice opening 72a and the compressed space 14a led to the outside are in fluid communication. In the case of the 90° rotation angle shown in FIG. 3, the orifice opening 72a of the fluid return 70 is in direct fluid communication with the compressed chamber 14b led to the outside, for example, over its entire area. In the rotation angle range of 270° to 360°, the orbiting scroll 31 closes the orifice opening 72a again.

[0197] At a rotation angle of 20°, the pressure of the refrigerant in the compressed space 14b that is just in fluid communication with the orifice opening 72a is already slightly higher than the suction pressure. This is because this compressed space 14b has been closed at the immediately preceding rotation angle of 0° (reference numeral 101) and has already been slightly reduced until the rotation angle of 20°.

[0198] In the following example, it is assumed that the suction pressure is 3 bar. In that case, the pressure of the refrigerant in this compressed space 14b is, for example, 3.08 bar at a rotation angle of 20°. Until the rotation angle of 270°, the pressure of the refrigerant in this compressed space 14b continuously rises to 4.76 bar in this example. In that case, the time-averaged value of the pressure of the refrigerant in the compressor channel 26 at the orifice opening 72a is 3.76 bar, that is, it is 0.76 bar higher than the suction pressure of 3 bar. This is a non-limiting example for a specific operating state.

[0199] Therefore, in the embodiment according to FIG. 3, the time-averaged value of the pressure of the refrigerant in the compressor channel 26 at the position of the orifice opening 72a of the fluid return 70 is, for example, · at a suction pressure of 1 bar, 126% of this suction pressure, · at a suction pressure of 3 bar, 125% of this suction pressure, · at a suction pressure of 5 bar, 124% of this suction pressure, and At 7 bar suction pressure, it is 123% of this suction pressure.

[0200] In a variant of the embodiment not shown, the orifice opening 72a of the fluid return 70 is in the region A M,3 When the position angle is shifted to ε1 = γ - 295°, the time average value of the pressure of the refrigerant in the compressor channel 26 at the position of the orifice opening 72a of the fluid return 70 is, for example, in the range of 138% to 142% of the respective suction pressure, depending on the operating conditions.

[0201] The orifice opening 72a of the fluid return 70 is, in a variant of the embodiment not shown, in the region A M,3 When the position angle is shifted to ε1 = γ - 190°, the time average value of the pressure of the refrigerant in the compressor channel 26 at the position of the orifice opening 72a of the fluid return 70 is, for example, in the range of 107% to 109% of the respective suction pressure, depending on the operating conditions.

[0202] Another area A for placement of orifice opening 72b M,4 is that the orifice opening 72b of the fluid return 70 therein is ε min,2 = γ - 120° ~ε max = γ, and the orifice opening 72b is further positioned such that it is scanned only by the inwardly directed compression space 14a and is scanned by the orbiting scroll 31 exactly once per revolution.

[0203] FIG. 7 shows, by way of example, an area A having a position angle ε2=γ−68°. M,4The position of the orifice opening 72b in [the relevant context] is recorded. The orifice opening 72b is further arranged at this position angle ε2 inside the compressor channel 26. Thereby, this orifice opening 72b is scanned only by the compressed space 14a led inward. Therefore, the orifice opening 72b is not in direct fluid communication with any one of the compressed spaces 14b led outward at any time. This orifice opening 72b can be formed instead of or in addition to the other orifice opening 72a of the fluid return 70 shown in FIG. 7.

[0204] When the compression chambers 14a and 14b are closed, the position angle of the compressed chamber 14b led inward is shifted by +180° with respect to the position angle of the compressed chamber 14a led outward. Since the position angle of the orifice opening 72b is also shifted by +180° in the same way with respect to the position angle of the orifice opening 72a, the pressure ratio at the orifice opening 72b occurs in the same way as the pressure ratio at the orifice opening 72a during rotation.

[0205] In an embodiment not shown, the orifice opening of the fluid return 70 can be arranged, for example, at a position angle in the range of ε max,1 ~ ε min,2 Such an orifice opening can be arranged at this position angle in the central region of the compressor channel 26. As a result, it is completely closed by the orbiting scroll 31 twice per rotation and is alternately in fluid communication with the compressed chamber 14a led inward and the compressed chamber 14b led outward. Thereby, the average pressure of the refrigerant at this orifice opening is between the average pressure of the refrigerant in the compressed chamber 14b led outward outside the compressor channel 26 at this position angle and the average pressure of the refrigerant in the compressed chamber 14a led inward inside the compressor channel 26 at this position angle. As already described elsewhere, the period during which the orifice opening is completely closed by the orbiting scroll 31 can be ignored for the calculation of the average pressure of the refrigerant at the orifice opening.

[0206] The scroll compressor 1 further includes a second oil return 82. The second oil return 82 returns oil from the oil separator 45 into the contact pressure chamber 80. The second oil return 82 includes a second oil inlet 81 in the oil separator 45 and a throttle valve 83 disposed between the second oil inlet in the second oil return 82 and the contact pressure chamber 80.

[0207] During operation, due to the discharge pressure prevailing in the oil separator 45, the oil is pushed through the second oil inlet 81 into the second oil return 82. The pressure of the oil is reduced by the throttle valve 83. The pressure drop in the throttle valve 83 affects the contact pressure.

[0208] The oil in the contact pressure chamber 80 contributes to the lubrication of the swash plate 30. Further, a very small part of the oil may pass through the swash plate 30 and enter the interior of the compression section 10.

[0209] The scroll compressor 1 shown in FIG. 1 further includes a reference communication portion 84 between the internal space of the contact pressure chamber 80 and the reference opening 86. The reference opening 86 is disposed in the swivel base 32 of the swash plate 30, more precisely in the compressor channel of the swash plate 30. The reference communication portion 84 affects the contact pressure in the contact pressure chamber 80 according to the operating state of the scroll compressor 1. The reference communication portion 84 communicates from the contact pressure chamber 80 through the swash plate 30 to the reference opening 86 of the swivel base 32.

[0210] The reference opening 86 of the reference communication part 84 is arranged more inwardly than the orifice openings 59a, 59b of the direct oil return 50 when viewed in the radial direction. FIG. 3 shows the position of the reference opening 86 of the reference communication part 84 in the outlet region of the compressor channel of the swivel disk 30. Therefore, the reference communication part 84 can hardly or not at all contribute to the lubrication of the radially outer regions of the fixed scroll 21 and the swivel scroll 31. The reference opening 86 is not arranged in the inlet region of the compressor channel of the swivel disk 30. Therefore, during the operation of the scroll compressor 1, no direct fluid communication is provided between the inlet 11 of the compression section 10 and the reference opening 86.

[0211] Optionally, the reference communication part 84 includes a throttle valve 85. The throttle valve 85 contributes to the adjustment of the contact pressure.

[0212] The second oil inlet 81 of the second oil return 82 is arranged in the bottom region of the oil separator 45. In particular, it is arranged below the first oil inlet 51 of the direct oil return 50. During operation, when the oil level in the oil separator 45 drops to a level below the first oil inlet 51, the first oil inlet 51 becomes dry and no longer receives oil supply. However, oil is still supplied to the second oil inlet 81. Thereby, the oil supply of the second oil return is prioritized over the oil supply of the direct oil return 50. In that way, it is ensured that the contact pressure is maintained even in case of oil shortage. The constant lubrication of the compression section 10 is maintained by the oil entering through the outside of the swivel disk 30 and by the oil returning from the external refrigerant circuit into the inlet 11 of the compression section 10. Further, especially when the oil level in the contact pressure chamber is very high, the oil can reach from the contact pressure chamber 80 into the compression section 10 through the reference communication part 84.

[0213] The scroll compressor 1 further includes an electric motor and an inverter (not shown) for the electric motor. The scroll compressor 1 can be integrated into the refrigerant circuit of a vehicle. The scroll compressor 1 can be incorporated, for example, into an electric vehicle or a hybrid vehicle.

[0214] FIG. 5 shows a longitudinal section of a compression section 10, a discharge pressure chamber 40, an oil separator 45, and a direct oil return 50 for directly returning oil from the oil separator 45 into the compression section 10, according to a second embodiment of the scroll compressor according to the present invention. The remaining elements of the scroll compressor are not shown. The scroll compressor and its components correspond to the structure and function of the scroll compressor 1 of FIG. 1, unless otherwise specified. The same reference numerals are used for the same elements.

[0215] FIG. 6 shows a cross section along the cutting line A of FIG. 5.

[0216] FIGS. 5 and 6 show that a degassing chamber 54 is formed outside the discharge pressure chamber 40 in the radial direction (perpendicular to the central axis of the fixed disk 20) and surrounds the discharge pressure chamber 40. The degassing chamber 54 has a (at least substantially) hollow cylindrical basic shape. The discharge pressure chamber 40 has a (at least substantially) cylindrical basic shape. The discharge pressure chamber 40 and the degassing chamber 54 are coaxially arranged. The hollow cylindrical jacket wall 41 of the discharge pressure chamber 40 separates the discharge pressure chamber 40 and the degassing chamber 45 from each other. In this way, the space around the jacket wall 41 that would otherwise not be used is advantageously utilized.

[0217] The discharge pressure chamber 40 is in direct fluid communication with the oil separator 45 via an opening 42. Similar to FIG. 1, optionally, a check device can be formed at the outlet 11 of the compression unit 10 (not shown).

[0218] The above-described embodiment with the direct oil return 50 enables particularly efficient operation and has high reliability.

Description of Signs

[0219] 1 Scroll compressor 10 Compression section 11 Inlet (of the compression section) 12 Outlet (of the compression section) 13 Check valve 14a, 14b, 14c Compression space 20 Fixed disk 21 Fixed scroll 22 Fixed base 24 Inner end (of the fixed scroll) 25 Outer end (of the fixed scroll) 26 Compressor channel (of the fixed disk) 28 Outlet opening (of the fixed disk) 30 Swivel disk 31 Swivel scroll 32 Swivel base 34 Outer end (of the swivel scroll) 40 Discharge pressure chamber 41 Jacket wall 42 Opening 45 Oil separator 46 Oil separator outlet opening 50 Direct oil return 51 First oil inlet 52 First fluid communication part 53 First flow valve (throttle valve) 54 Degassing chamber 55 Oil inlet 56 Second fluid communication part 57 Second flow valve (throttle valve) 58 Branch part 59a, 59b Orifice opening (of the direct oil return) 70 Fluid return 71 Fluid inlet 72a, 72b Orifice opening (of the fluid return) 80 Contact pressure chamber 81 Second oil inlet 83 Flow valve (throttle valve) 84 Reference communication part 84 Flow valve (throttle valve) 86 Reference opening 90 Housing 91 Suction port 92 Discharge port 93 Suction pressure chamber A M,1 , A M,2 , A M,3, A M,4 Region ε 1, ε 2, ε min, ε max Position angle ε 1, ε 2, εmin, εmax Position angle γ Position angle of the outer end of the compressor channel θ Position angle R I (γ) Radial distance from the inner surface of the fixed scroll at the outer end of the compressor channel B K Width of the compressor channel in the radial direction at the outer end of the compressor channel R A (θ - 360°) Radial distance from the outer surface of the fixed scroll at the position angle θ - 360°

Claims

1. A scroll compressor (1) for compressing a fluid, comprising: A compression section (10), comprising: - An inlet (11) of the compression section (10) for sucking the fluid into the compression section (10), and an outlet (12) of the compression section (10) for discharging the compressed fluid from the compression section (10); - A fixed disk (21) having a fixed scroll (21); and - A swivel disk (30) having a swivel scroll (31), which is swivellable relative to the fixed disk (20) along a compression direction (100) for transporting the fluid from the inlet (11) of the compression section (10) to the outlet (12) of the compression section (10) and compressing the fluid therebetween. The compression section (10); An oil separator (45) for separating oil from the compressed fluid; Including; The scroll compressor (1) further comprises a direct oil return (50) for directly returning oil from the oil separator (45) into the compression section (10), the direct oil return (50) comprising at least one orifice opening (59a, 59b). The direct oil return (50) includes a first flow rate valve (53). The direct oil return (50) includes a degassing chamber (54) disposed between the first flow rate valve (53) and the orifice opening (59a, 59b) of the direct oil return (50). The scroll compressor (1) is characterized in that it comprises a fluid return (70) for returning the fluid from the degassing chamber (54) into the compression section (10). Scroll compressor (1).

2. The scroll compressor (1) according to claim 1, wherein the orifice openings (59a, 59b) of the direct oil return (50) are disposed on the fixed disk (20).

3. The fixed disk (20) comprises a fixed scroll (21), the fixed scroll (21) being disposed on a fixed base (22) of the fixed disk (20) and forming a spiral compressor channel (26) of the fixed disk (20). The scroll compressor (1) according to claim 2, characterized in that it is as described above.

4. The orifice openings (59a, 59b) of the direct oil return (50) are arranged in the suction region of the compressor channel (26) which, during operation, is in direct fluid communication, at least temporarily, with the inlet (11) of the compression section (10), and / or are arranged outside the compressor channel (26), the scroll compressor (1) according to claim 3.

5. The orifice openings (59a, 59b) of the direct oil return (50) are It is arranged at a position angle in the range of γ - 30° to γ + 30°, where γ is the position angle of the outer end of the compressor channel (26), and the radial distance R from the center of the fixed disk (20) M,1 is arranged here, where R M,1 is (R I (γ) - B K ) to R I (γ), and R I (γ) is the radial distance of the inner surface of the fixed scroll (21) at the outer end of the compressor channel (26), and B K is the width of the compressor channel (26) along the radial direction at the outer end of the compressor channel (26), or Outside the fixed scroll (21), at a position angle in the range of θ - 30° to θ + 30°, and at a radial distance R from the center of the fixed disk (20) M,2 is arranged here, where θ = γ + 180°, and R M,2 is R A (θ - 360°) to R A (θ - 360°) + B K is in the range of, and R A (θ - 360°) is the radial distance of the outer surface of the fixed scroll (21) at the position angle θ - 360° The scroll compressor (1) according to claim 3 or 4.

6. The orifice opening (72a) of the fluid return (70) is arranged in the central region of the compressor channel (26) of the fixed disk (20), the central region of the compressor channel (26) consisting of all regions of the compressor channel (26) which cannot be in direct fluid communication with either the inlet (11) or the outlet (12) of the compression section (10), the scroll compressor (1) according to any one of claims 3 to 5.

7. During the compression operation, at least one compression space (14a, 14b, 14c) is formed between the orbiting scroll (31) and the fixed scroll (21), and the at least one orifice opening (59a, 59b) is not scanned by any of the compression spaces (14a, 14b, 14c) at any time, the scroll compressor (1) according to any one of claims 1 to 6.

8. The direct oil return (50) includes a second flow valve (57) arranged behind the degassing chamber (54), the scroll compressor (1) according to any one of claims 1 to 7.

9. During the compression operation, the intermediate pressure in the degassing chamber (54) is adjusted such that it is in the range 0.2 bar to 6 bar higher than the suction pressure of the compression section (10), the scroll compressor (1) according to any one of claims 1 to 8.

10. Equipped with a discharge pressure chamber (40), the oil separator (45) is in direct fluid communication with the outlet (12) of the compression section (10) via the discharge pressure chamber (40), the scroll compressor (1) according to any one of claims 1 to 9.

11. The degassing chamber (54) is formed outside the discharge pressure chamber (40) in the radial direction and surrounds the discharge pressure chamber (40). The scroll compressor (1) according to claim 10, characterized in that.

12. A contact pressure chamber (80) in which a contact pressure acts during the compression operation, wherein the orbiting disk (30) is pressed against the fixed disk (20) by the contact pressure, the contact pressure chamber (80); A second oil return (82) for returning oil from the oil separator (45) into the contact pressure chamber (80); The scroll compressor (1) according to any one of claims 1 to 11, further comprising:

13. The scroll compressor (1) according to claim 12, characterized in that the second oil return (82) is prioritized over the direct oil return (50) in case of oil shortage.

14. The direct oil return (50) includes a first oil inlet (51) opened into the oil separator (45), and the second oil return (82) includes a second oil inlet (81) opened into the oil separator (45). The scroll compressor (1) according to claim 12 or 13, characterized in that the first oil inlet (51) is disposed above the second oil inlet (81).

15. A reference opening (86) disposed in the compression section (10), and a reference communication section (84) for forming a fluid communication between the contact pressure chamber (80) and the reference opening (86) to affect the contact pressure based on a reference pressure acting on the reference opening (86) during operation. The scroll compressor (1) according to any one of claims 12 to 14, characterized in that it comprises:

16. The degassing chamber (54) is 30 cm 3 to 150 cm 3 in volume, and the scroll compressor (1) according to any one of claims 1 to 15 is characterized in that.

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