Scroll machine

Abstract

The invention relates to a scroll machine (2) for conveying a fluid. The scroll machine (2) comprises a first scroll (36), which has a first base plate (36b) and a first spiral wall (36a) protruding from the first base plate (36b) and forming a first spiral path (36d), and a second scroll (24), which has a second base plate (24b) and a second spiral wall (24a) protruding from the second base plate (24b), the second spiral wall engaging in the first spiral path (36d) of the first scroll (36) and forming a number of conveying chambers (38, 50) with the first spiral wall (36a). In a central region of the first base plate (36b), a discharge opening (42) is formed, through which the conveyed fluid escapes into a high-pressure chamber of the scroll machine (2) during proper operation. The discharge opening (42) is delimited, at least on the entry side, by a control edge (42a), which, during proper compression operation, is first swept by the second spiral wall (24a) and the curvature of which approximates a radially outwardly facing outer contour (24e) of the second spiral wall (24a), and by a trailing edge (42b), the curvature of which approximates, at least in parts, a radially inwardly facing inner contour (36e) of the first spiral wall (36a) and which is closer to an inner spiral end (36f) of the first spiral wall (36a) than the control edge (42a) is.

Description

[0001] Description

[0002] Scroll machine

[0003] The invention lies in the field of displacement machines according to the spiral principle and relates to a scroll machine, in particular in the form of a scroll compressor, preferably as an electric refrigerant drive, in particular as a refrigerant compressor for refrigerant of a vehicle air conditioning system.

[0004] Motor vehicles are regularly equipped with air conditioning systems that climate-control the vehicle interior using a system forming a refrigerant circuit. Such systems generally have a circuit containing a refrigerant. The refrigerant, for example R-744 (carbon dioxide, CO2) or R-134a (1,1,1,2-tetrafluoroethane), is heated in an evaporator and compressed by a (refrigerant) compressor. The refrigerant then releases the absorbed heat via a heat exchanger before being fed back to the evaporator via a throttle.

[0005] A so-called scroll machine is often used as a refrigerant compressor to compress a refrigerant. The design and operation of such a scroll machine, used as a compressor for the refrigerant in a motor vehicle air conditioning system, is described, for example, in DE 10 2012 104 045 A1. Key components of such a scroll machine are two scroll parts (“scrolls”) that can move relative to one another. The system usually also contains oil in droplet form or as a mist, which is at least partially separated from the refrigerant (which is usually gaseous after compression) after compression. The refrigerant (possibly with oil residues) is then introduced into the air conditioning circuit, while the separated oil can usually be fed to the moving parts within the scroll machine to lubricate them.The scroll components are typically designed as a stationary, fixed scroll (fixed scroll, displacement scroll) and a movable, orbiting scroll (counter scroll, rotor scroll). Both scrolls are fundamentally similar in design and each comprise a base plate (main body, scroll disk) and a spiral (worm-shaped) wall (spiral wall, scroll wall) extending axially from the base plate. When assembled, the spiral walls of the two scrolls are nested within each other, forming several conveying chambers between the scroll walls, which touch each other in sections.

[0006] To drive the movable scroll, an electric motor is typically provided, the motor shaft of which (A-side, i.e. output side) is coupled to the movable scroll part by means of an eccentric shaft journal (also: “shaft pin”).

[0007] An orbiting movement, here and in the following, is understood in particular to mean an eccentric, circular movement path in which the movable scroll itself does not rotate about its own axis. During operation, the two scrolls are kept as close to each other as possible axially. During each orbiting movement, essentially crescent-shaped (compression or delivery) chambers are formed between the spiral walls. As the two scrolls move toward each other (at least during a compression process), their volume migrates from the outside along the spiral walls toward the center axis of the respective scroll, thereby progressively reducing the volume (and thus compressing the medium contained within).

[0008] The orbiting movement of the movable scroll is usually achieved, among other things, by an anti-rotation mechanism, which prevents the scroll from rotating on its own. This is usually connected between the movable scroll and a stationary element of the scroll machine. The anti-rotation mechanism is often formed by a number of circular, pocket-like openings ("rings") arranged on a circular path, usually in the movable scroll, and associated pins ("pins"), usually arranged in the stationary element. The pins engage in the circular openings of the movable scroll, each forming a so-called pin-ring contact. During (compressor) operation, the pins slide along the circular opening walls, preventing self-rotation. To reduce friction and improve service life, race rings (sliding rings), for example, are inserted into the openings.Due to this design, the anti-rotation mechanism is also called a “pin-ring system”.

[0009] The motor shaft is usually mounted in a bearing plate (also called a "center plate") by means of a bearing. The pins of the anti-rotation mechanism are usually fixed (especially force-locked) in the bearing plate.

[0010] For example, such anti-rotation mechanisms have six such pin-ring contacts. The pin-ring contacts are arranged offset from each other by 45 to 75°.

[0011] To guide the conveyed medium (fluid), outlet holes (also known as outlet openings) are usually inserted into the base plates of the scroll spirals in order to expel the fluid (e.g. refrigerant) compressed between the spirals into the high-pressure area of ​​the scroll machine. In most cases, check valves in the form of so-called tongue valves (flutter valves, reed valves) are used to prevent the compressed fluid from flowing back. However, the outlet holes always create a so-called dead volume, as is also known from other compressor principles. In reciprocating piston compressors, for example, the dead volume limits the achievable compression ratio, since already compressed fluid collects in the dead volume and then expands again. This so-called back expansion also disadvantageously limits the suction of further fluid.

[0012] Due to the scroll geometry and the need for an outlet bore, the so-called backflow effect occurs in scroll machines. This effect occurs as soon as the pressure ratios regulated by the fluid circuit (e.g., the refrigerant circuit) are greater than the geometrically predetermined pressure ratios of the scroll spirals themselves. The intrinsic pressure ratio of a scroll machine is determined by its scroll geometry. The intrinsic pressure ratio is generally defined by the ratio of the swept volume (suction chambers) to the innermost chamber volume at the time of discharge. Depending on the scroll characteristics, a precise definition, such as that of a reciprocating compressor (swept volume / dead volume), is not possible.

[0013] The backflow phenomenon occurs particularly when the scroll coils are expelling the compressed refrigerant from the innermost (scroll) chamber into the high-pressure chamber. At this time, the (tongue) valve is open. At this operating point, the compression ratio is greater than the internal compression ratio of the coils. As the scroll coils move further, the so-called backflow gap opens between the outlet bore and a compression chamber following the innermost chamber (there are always two symmetrical compression chambers, except for the innermost chamber, which is also called the "discharge chamber"). This causes compressed fluid to flow back from the high-pressure chamber via the open valve, through the outlet bore into this discharge chamber. The pressure in the outlet bore consequently drops, and the valve closes. The pressure in the outlet bore now drops suddenly, as no more compressed fluid can flow through the valve.The fluid from the innermost chamber between the scroll coils also expands. The re-expanded gas from the innermost chamber and the outlet bore creates an oscillating pressure wave in the subsequent discharge chamber.

[0014] The backflow described above thus causes pressure fluctuations due to rapid pressure equalization within the chambers, and consequently fluctuations in the contact forces between the two scrolls and their anti-rotation system. These discrete pulses lead to acoustic peaks, vibrations, and / or force fluctuations, which in turn are undesirable during operation of the scroll machine, especially when used in motor vehicles.

[0015] The invention is based on the object of providing an improved scroll machine.

[0016] This object is achieved according to the invention by a scroll machine having the features of claim 1. Advantageous and partly inventive embodiments and further developments of the invention are set out in the subclaims and the following description.

[0017] The scroll machine according to the invention is designed and provided for conveying a fluid, in particular a refrigerant in a vehicle air conditioning system. For this purpose, the scroll machine has a first, stationary scroll with a first base plate and a first spiral wall protruding from the first base plate. This first spiral wall forms a first spiral flight (i.e. assigned to the first scroll). The scroll machine also has a second scroll with a second base plate and with a second spiral wall protruding from the second base plate, which engages in the first spiral flight of the first scroll and forms a number of conveying chambers with the first spiral wall. The second scroll is designed to be orbitable, i.e. in particular, this second scroll orbits relative to the first, stationary scroll during normal operation of the scroll machine.An outlet opening is formed in a central region of the first base plate, through which opening the fluid conveyed during normal operation of the scroll machine escapes into a high-pressure chamber of the scroll machine arranged rearward to this base plate. According to the invention, the outlet opening is delimited at least on the inlet side (i.e. in particular on a side of the first base plate facing the first spiral flight) by a control edge and a trailing edge. The control edge is arranged and aligned such that it is swept over by the second spiral wall first (i.e. before the trailing edge) during normal compression operation. A curvature of the control edge is also approximated to a radially outward-facing outer contour of the second spiral wall, i.e. in particular approximated or matched to its shape.The trailing edge is arranged closer to an inner spiral end of the first spiral wall than the control edge. The curvature of the trailing edge is at least partially approximated to a radially inwardly facing inner contour of the first spiral wall (in particular, adapted to or shaped to match it).

[0018] Thus, the outlet opening, specifically its “bore profile”, is designed in particular to deviate from a typically typical circular shape and is at least partially approximated in shape and preferably also in orientation to an edge contour (outer or inner contour) of the second and also the first spiral wall.

[0019] Due to the orbiting motion of the second scroll and the spiral shape of the spiral walls, the aforementioned delivery chambers are roughly crescent-shaped (seen in the direction of the wall height of the spiral walls). A respective delivery chamber that is open at the edge (i.e. when the outer spiral end is not yet in contact with the other spiral wall) is also referred to as a suction chamber. As soon as the suction chambers are closed by the orbiting motion of the scrolls, they become the actual delivery chamber, in which compression already occurs, as their crescent-shaped volume is successively reduced towards the center of the spiral during the orbiting motion. Radially inward, the delivery chambers there connect or merge in a process also known as "merging" to form the common discharge chamber, which conveys the compressed fluid, e.g. a refrigerant-oil mixture, into a downstream high-pressure chamber via the outlet opening.The angular position of the motor shaft at which the delivery chambers merge to form the discharge chamber is also referred to as the merging angle.

[0020] In particular, the above-described design of the outlet opening, i.e., its above-described control and trailing edges (which, in particular, also describe the profile of the outlet opening on the inlet side), advantageously enables backflow from the "last" (or innermost) delivery chamber (hereinafter referred to as the "discharge chamber") into one of the delivery chambers located upstream, opposite the compression direction, to be at least reduced, if not completely eliminated. This is because, during normal operation, the spiral wall of the second scroll sweeps over the first base plate within the first spiral flight and thus also over the outlet opening.In the case of a conventional circular outlet opening, due to the usually required cross-sectional area of ​​the outlet opening, a connection between the discharge chamber and the upstream conveying chamber is regularly formed at a comparatively early point in time via the second spiral wall and through the outlet opening. If the control edge of the outlet opening is aligned with the outer contour of the second spiral wall, as provided by the present invention, this spiral wall can sweep over the outlet opening without backflow occurring, or only at a significantly later point in time compared to a circular outlet opening (with the same cross-sectional area as the one designed according to the invention). This allows unwanted pressure surges and their consequences to be avoided or at least significantly reduced.

[0021] By means of the control edge, in particular its positioning and its contour, a point in time (more precisely a position of the second scroll along its orbital path, preferably a value range of a movement angle of the second scroll) can be specified at which the control edge (when the second scroll moves in the compression direction) emerges again under the outer side (outer contour) of the second spiral wall and thus backflow could occur.

[0022] While delayed backflow is also possible with a circular outlet opening, this requires a significant reduction in cross-sectional area, which results in disadvantages in terms of volume flow through the outlet opening.

[0023] Typically, the spiral walls of modern scroll machines, as in the scroll machine described here and below, are designed with a wall thickness that varies along the length of the spiral wall. In particular, the inner end of each spiral wall is thickened. The position of the outlet opening, as well as its control edge and its trailing edge, are preferably selected such that the fluid contained in the discharge chamber is completely discharged, or at least with the exception of a negligible residual amount (i.e., the outlet opening remains connected to the discharge chamber) before the control edge is also swept over by the outer edge of the second spiral wall, thus allowing backflow to occur. At the very least, however, a delay in backflow should be enabled compared to a circular outlet opening with the same cross-sectional area.For this purpose, the position of the outlet opening as well as its control edge and its trailing edge are expediently designed such that the second spiral wall covers the outlet opening at least by more than 50% of the cross-sectional area, in particular more than 70%, preferably more than 90%, before the control edge is swept over by the outer edge of the second spiral wall.

[0024] Preferably, a size (e.g., a cross-sectional area) and / or a position of the outlet opening is selected as a function of a wall thickness, in particular of the second spiral wall, and / or the distance between an inner spiral end of the second spiral wall and an inner spiral end of the first spiral at a position (along the orbital path) at which a compression ratio for a predetermined operating point is achieved. This is because positioning the outlet opening as close as possible to the "end" of the orbital path enables a comparatively high discharge volume, since this reduces a dead volume that is predetermined by a "sickle chamber" remaining when sweeping over the outlet opening and that can no longer be emptied through the outlet opening as the orbital movement progresses.However, a compromise must preferably be found between the largest possible outlet opening – to allow sufficient volume flow through the outlet opening – and compression with as little dead volume as possible (the dead volume includes the volume of the outlet opening itself as well as the crescent-shaped volume of the discharge chamber remaining when the trailing edge is covered by the second scroll wall). The position of the second scroll along its orbital path, which is characteristic of the acceptable residual or dead volume of the discharge chamber, can in turn be used to determine the distance between the two scroll walls, which in turn is taken into account in the design of the outlet opening.

[0025] In a preferred embodiment, the curvature of the control edge is approximated (simulated) to the outer contour of the second spiral wall in a range of a spiral angle between 0 and 150 degrees, in particular between 20 and 130 degrees, preferably between 20 and 110 degrees, of the second scroll. The spiral angle is understood here and below to be the angle measured from a contact point of the inner end of the second spiral wall in the direction of an inlet opening (i.e., away from the center of the spiral walls) of the scroll. This contact point is preferably located at a position at which the second scroll is positioned at a position of 170 to 360 degrees (or 210 to 350 degrees) at the merging angle. Thus, the control edge is approximated (matched or simulated) to the outer contour of the second spiral wall, particularly in the region of the inner spiral end, which is preferably described by the aforementioned angle ranges.

[0026] In particular, the profile of the outlet opening, at least on the inlet side, is approximated to a biconvex lens with a small (particularly in the area of ​​the trailing edge) and a larger radius of curvature. To align the "alignment" of the outlet opening profile with the spiral wall, a "longitudinal axis" of the lens-like profile is aligned, for example, parallel to a longitudinal axis or "neutral" fiber of the second spiral wall, or at least at a shallow angle of incidence to it if the latter is arranged to cover the outlet opening.

[0027] According to a practical embodiment, the control edge has the same curvature - preferably over its entire length - as the outer contour of the second spiral wall. This allows the outlet opening to be covered by the second spiral wall over as long a section as possible and to be sealed off from the delivery chamber adjoining the discharge chamber, or more precisely, preceding it, thus enabling the largest possible cross-sectional area of ​​the outlet opening. The trailing edge optionally also has the same curvature as the inner contour of the first spiral wall. In principle, the trailing edge can also be curved convexly and concavely and can thus be guided at least partially around the inner spiral end of the first spiral wall.

[0028] The trailing edge and the control edge are expediently connected to each other by means of two transition edges with a comparatively small radius of curvature.

[0029] The trailing edge of the outlet opening can expediently be pushed relatively close to the central end of the first scroll wall, so that the outlet opening is not yet completely covered by the second scroll wall, or is only just completely covered, at a time (particularly with respect to the orbital movement of the second scroll) when the relative movement of the two scrolls to each other has reached its "inner" reversal point. In other words, the outlet opening can remain open for as long as possible, and the dead volume within the discharge chamber can be reduced, as described above.

[0030] In a practical design, the outlet opening has an inlet chamfer on the inlet side in the area of ​​the trailing edge. This means that the trailing edge, or a section of it, is rounded or beveled at this point. However, in the area of ​​the control edge, the outlet opening has a comparatively sharp edge. This allows a "smooth" and thus aerodynamically favorable transition to be formed on the chamfered edge. The sharp control edge, on the other hand, enables the longest and most effective sealing effect possible in conjunction with the second spiral wall.

[0031] In particular, in order to be able to keep the outlet opening open over the longest possible range of movement of the second spiral wall, according to an advantageous embodiment, the second spiral wall has a wall thickness taper in the region of a wall head end facing away from the second base plate, from a wall inner side facing the outlet opening, as well as in the region with which the second spiral wall sweeps over the outlet opening during intended compression operation. In other words, the second spiral wall is recessed from the wall inner side to part of its wall thickness, so that - even if the second spiral wall would actually already partially cover the outlet opening - the outlet opening lies in the region of this recess and is therefore still open over its entire surface or with a relatively larger cross-sectional area.

[0032] In a preferred embodiment, the outlet opening is widened on the outlet side in a diffuser-like (also: "trumpet-like") configuration. This widening of the outlet opening profile creates a diffuser-throttling effect and thus reduces the flow velocity toward a valve, which is preferably arranged on the outlet side of the first base plate and closes the outlet opening unidirectionally. Furthermore, pressure losses can be reduced, and due to the reduced flow velocity, the valve stroke (i.e., the stroke of a sealing surface of the valve) can be made smaller. A reduced valve stroke also advantageously usually leads to a reduction in noise when the valve closes.

[0033] Preferably, the diffuser-like extension of the outlet opening begins in one third of the outlet-side length of the outlet opening. In other words, the diffuser-like extension is located in the last third of the bore-like outlet opening, viewed in the outlet direction.

[0034] According to a suitable embodiment, the diffuser-like extension of the outlet opening has an opening angle between 0 and 30 degrees, in particular between 5 and 25 degrees, preferably between 10 and 20 degrees. The opening angle is preferably understood in the longitudinal section of the outlet opening as the angle between the two (opposite side walls, viewed in cross-section) side walls of the outlet opening (cf. a funnel).

[0035] In an optional variant, the outlet opening is recessed, particularly in a stepped manner, into the rear side of the first base plate. This allows the valve to respond more effectively, ie, more effectively.

[0036] The valve described above is preferably designed as a check valve, in particular as a so-called flutter valve (or also: "reed valve") and thus has a type of tongue ("valve tongue") as a closing body (valve flap), which is preferably made of a flexible material, i.e. one that can be bent for the opening movement. In particular, the valve also has an opening stop against which the valve tongue can strike when opening in order to prevent excessive bending and, in the worst case, damage. Preferably (optionally also due to the possibility described above due to the reduced flow velocity) the valve stroke is limited compared to conventional (circular cylindrical) outlet openings.

[0037] In a particularly practical embodiment, the outlet opening is formed in a bore insert manufactured separately from the first base plate. This bore insert is, for example, pressed, screwed, glued, or welded into a corresponding bore in the first base plate. The bore insert advantageously makes it possible to provide a type of modular system for the scroll machine, in which, with an existing and consistent scroll geometry, different bore inserts and thus different outlet opening geometries can be used, for example, for different areas of application and thus also operating points of the scroll machine (i.e., in particular, compression ratios, absolute pressures, speed, etc.). This can, for example, reduce inventory costs.

[0038] In an alternative but nevertheless expedient embodiment, in which the first scroll is formed at least partially, but preferably completely, using an aluminum die-casting process, the outlet opening is also already formed using this aluminum die-casting process. This also has the advantage that such a process can be manufactured comparatively precisely and, in particular, near-net-shape. In particular, aluminum die-cast components have only a comparatively lightly structured "casting skin," the fluidic influence of which on the fluid within the outlet opening can, however, be neglected. In particular, the first scroll is manufactured without any post-processing, at least within the outlet opening.

[0039] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings:

[0040] Fig. 1 shows a side view schematically of a scroll machine according to the prior art,

[0041] Fig. 2 shows a partial sectional view of the scroll machine according to the state of the art,

[0042] Fig. 3, 4 in a partial sectional view III-III according to Fig. 2, a section of the scroll machine according to the state of the art in normal operation at two different times,

[0043] Fig. 5 in a partial sectional view III-III according to Fig. 2 schematically and in detail an embodiment of a first of two scrolls of a scroll machine according to the invention,

[0044] Fig. 6 in a detailed view a partial sectional view III-III according to Fig. 2 with both scrolls of the scroll machine,

[0045] Fig. 7 shows a detailed schematic view of a bore insert for an outlet opening of the scroll machine from an inlet side,

[0046] Fig. 8 in a partially transparent view of the bore insert with a view of an outlet side,

[0047] Fig. 9 shows the bore insert in a longitudinal section,

[0048] Fig. 10 shows a perspective partial sectional view of the first scroll of a further embodiment of the scroll machine according to the invention, and

[0049] Fig. 11 in view according to Fig. 6 another embodiment of the scroll machine.

[0050] Corresponding parts and sizes are always provided with the same reference numerals in all figures. Fig. 1 shows a scroll machine, specifically a scroll compressor 2 for a fluid. The scroll compressor 2 is installed, for example, as a refrigerant compressor in a refrigerant circuit (not shown in detail) of an air conditioning system of a motor vehicle. The scroll compressor 2 is operated by an electric motor and, for this purpose, has an electric (electromotive) drive module 4 and a compressor module 6 coupled to the latter. A mechanical interface 8 is provided between the drive module 4 and the compressor module 6, by means of which the compressor module 6 is connected to the drive module 4.

[0051] The mechanical interface 8 serves as a drive-side bearing plate and forms an intermediate wall (see also Fig. 2), also referred to as a “center plate,” between the drive module 4 and the compressor module 6. The compressor module 6 is connected, specifically screwed, to the drive module 4 by means of flange connections 10 distributed around the circumference and extending in an axial direction A of the scroll compressor 2.

[0052] A housing section of a drive housing 12 of the scroll compressor 2 is designed as a motor housing 12a for accommodating an electric motor 13 (not shown in full). It is closed on the one hand by an integrated housing partition (not shown) to an electronics housing 12c provided with a housing cover 12b and containing motor electronics (electronics 14) that control the electric motor 13 during normal operation, and on the other hand by the mechanical interface 8 with the bearing plate. In the area of ​​the electronics housing 12c, the drive housing 12 has a connection section 16 with motor connections leading to the electronics 14 for electrically contacting the electronics 14 with an on-board electrical system of the motor vehicle.

[0053] The scroll compressor 2 has a (fluid or refrigerant) inlet or (refrigerant) inlet 18 for connection to the refrigerant circuit and a (refrigerant) outlet 20. The inlet 18 is formed in a region of the motor housing 12a facing the electronics housing 12c. The outlet 20 is formed on a bottom of a compressor housing 22 of the compressor module 6. When connected, the inlet 18 forms the low-pressure or suction side (suction gas side) and the outlet 20 forms the high-pressure or pump side (pump side) of the scroll compressor 2.

[0054] As can be seen from Fig. 2, the compressor module 6 of the scroll compressor 2 (shown here as an example for the prior art) has a movable scroll (scroll part, hereinafter referred to as the orbiting scroll, or "O-Scroll 24" for short) arranged in the compressor housing 22. This scroll is coupled by means of an eccentric, hereinafter referred to as "swing link 26", via a joining pin or shaft journal 28 to a (drive or motor) shaft 30 of the electric motor 13, which is guided into the mechanical interface 8 with the A-side (drive-side) bearing plate. A counterweight 31 is eccentrically connected to the swing link 26.

[0055] The swing link 26 is mounted in a roller or ball bearing 32 held in the O-scroll 24. Another roller or ball bearing 34, which supports the shaft 30, is located in the mechanical interface 8, which serves as the A-side bearing plate, and there in the intermediate wall (the center plate). The O-scroll 24 is driven in an orbiting motion during operation of the scroll compressor 2 by means of the shaft 30 and the shaft journal 28 eccentrically mounted in the shaft 30.

[0056] The scroll compressor 2 also has a fixed scroll (scroll part, referred to as "F-scroll 36") that is rigidly mounted in the compressor housing 22, i.e., fixed to the housing. Both scrolls (scroll parts) 24, 36 each have associated helical or spiral-shaped spiral walls 24a, 36a (scroll walls, scroll spirals) that protrude axially from a respective base plate 24b, 36b. The F-scroll 36 further has a circumferential boundary wall 36c forming the outer circumference (see also Fig. 3). The spiral walls 24a, 36a each form a spiral flight 24d, 36d. When assembled, the two scrolls 24 and 26 interlock with their spiral walls 24a, 36a, so that the spiral walls 24a, 36a are located in the respective other spiral threads 36d and 24d, respectively. The F-scroll 36 is also referred to as the first scroll, and the O-scroll 24 is referred to as the second scroll.

[0057] Between the scrolls 24, 36, i.e. between their scroll walls 24a, 36a and the base plates 24b, 36b (and thus in the spiral passages 24d, 36d), delivery chambers, referred to here as “compressor chambers 38”, are formed, the volume of which changes during operation of the electric motor 13 (see also Fig. 3).

[0058] As can be seen in Fig. 2, a backpressure chamber 40 (also known as a "backpressure chamber") is located between the A-side bearing plate formed by the mechanical interface 8 and the O-scroll 24, specifically in the intermediate wall. During operation, the refrigerant is introduced through the inlet 18 into the drive housing 12 and from there into the motor housing 12a. The aforementioned housing intermediate wall integrated into the drive housing 12 prevents the refrigerant from penetrating the electronics housing 12c. Within the drive housing 12, the refrigerant, which is mixed with the oil present in the refrigerant circuit, is drawn along the rotor 13a and the stator of the electric motor 13 through an opening (or several openings) in the intermediate wall to the compressor module 6. The refrigerant, specifically its mixture with oil, thus also serves to cool the electric motor 13.The compressor module 6 compresses the mixture of refrigerant and oil, with the oil serving to lubricate the two scrolls 24 and 36, thus reducing friction and increasing efficiency. The oil also serves as a seal to prevent uncontrolled leakage of the refrigerant located between the two scrolls 24 and 36.

[0059] The compressed mixture of refrigerant and oil is at least largely directed via a central outlet opening 42 (see also Fig. 3) and usually also two further bores 44 in the base plate 36b of the F-scroll 36 into a high-pressure chamber 45 within the compressor housing 22. On the outlet side, a check valve, here a so-called flutter valve 46, is arranged in the high-pressure chamber 45, by means of which a backflow of refrigerant through the outlet opening 42 or the bores 44 is to be prevented. Of the flutter valve 46, primarily a valve stroke limiter 48 for individual valve reeds 50 is shown here (in Fig. 2 lying flat on the base plate 26b and therefore not clearly visible).

[0060] The refrigerant is compressed by the O-scroll 24 orbiting, with its spiral wall 24a sliding along the spiral wall 36a of the F-scroll 36. Each compression chamber 38 "migrates" along both spiral walls 24a and 36a toward the central outlet opening 42, thereby shrinking in size. The enclosed refrigerant is thus compressed. The innermost discharge chamber is referred to below as the discharge chamber 52. Its size also decreases with the movement of the O-scroll 24. However, here the refrigerant is only further compressed until the pressure required to open the flutter valve 46 has built up in the discharge chamber 52. The compressed refrigerant then flows through the outlet opening 42 and the flutter valve 46 into the high-pressure chamber 45.

[0061] As can be seen from Fig. 3, the outermost compressor chambers 38 are initially open radially outwards. In this state, refrigerant can flow into or be sucked into the outer compressor chambers 38 (which, in this open state, are also referred to as suction chambers). As soon as the outer compressor chambers 38 are closed by the orbiting movement of the O-scroll 24 (see Fig. 4), they become the actual compressor chambers 38, whose crescent-shaped volume is successively compressed towards the center of the spiral during the orbiting movement. The angular position of the motor shaft 30 at which the outermost compressor chambers 38 are closed is also referred to below as the 0° position. Due to the geometry, there are always two compressor chambers 38 on the outside, located opposite each other across the center of the two scrolls 24 and 36 (cf. Fig. 3).The two radially innermost compressor chambers 38 connect or unite to form the aforementioned discharge chamber 52 in a process also referred to as "merging". The angular position of the motor shaft 30 at which this merging occurs is also referred to as the merging angle. As can be seen from Figs. 2 to 4, the outlet opening 42 is traditionally designed with a circular cross-section. The diameter is determined by flow and pressure control specifications. Fig. 4 shows a position of the O-scroll 24 in which its spiral wall 24a still seals the outlet opening 42 in the direction of the compressor chamber 38 located upstream of the discharge chamber 52. If the O-scroll 24 moves beyond this position, the spiral wall 24a exposes an edge region of the outlet opening 42 towards the compressor chamber 38 located upstream.This allows compressed refrigerant to flow from the discharge chamber 52 via the outlet opening 42 back into the upstream compressor chamber 38. This not only leads to a pressure loss, but also to refrigerant flowing back from the high-pressure chamber 45 toward the outlet opening 42. Until the flutter valve 46 closes, a portion can also flow back into the outlet opening 42. When the valve tongue 50 for the outlet opening 42 closes, noise is generated on the one hand, and shock waves and thus pressure fluctuations in the refrigerant on the other, both in the high-pressure chamber and in the compression and delivery chambers 52 and 38, respectively. The aim of the invention is to reduce these effects.

[0062] For this purpose, as is clear from Fig. 5, the outlet opening 42 is designed with a non-circular profile (or cross-section) that deviates from a circle. Specifically, the outlet opening 42 has a control edge 42a whose curvature approximates a radially outward-facing outer contour 24e of the spiral wall 24a of the O-scroll 24. Specifically, in Fig. 5, the control edge 42a has the same curvature as the outer contour 24e (see also Fig. 6). In addition, the outlet opening 42 also has a trailing edge 42b opposite the control edge 42a. The trailing edge 42b is arranged closer to an inner spiral end 36f of the spiral wall 36a of the F-scroll 36 than the control edge 42a. The curvature of the trailing edge 42b is at least partially approximated to a radially inwardly facing inner contour 36e of the spiral wall 36a.

[0063] The control edge 42a is shaped to the outer contour 24e of the spiral wall 24a over an angular range of a spiral angle SW of the spiral wall 24a of the O-scroll 24 from approximately 0 to 150 degrees. The spiral angle SW of the spiral wall 24a is counted (or measured) outward from a position at which the inner end piece (or spiral end 24f) of the spiral wall 24a rests against the spiral wall 36a of the F-scroll 36 with a contact point P, and the F-scroll 36 is arranged in a range of movement angles from 170 to 360 degrees according to the merging angle (see Fig. 6, dotted angular range of the spiral angle SW, starting from a surface normal of the spiral wall 24a at the contact point P). This position of the O-scroll 24 also corresponds approximately to the arrangement according to Fig. 4, where the contact point P is also shown.The profile of the control edge 42a is thus approximated in its shape and orientation to the boundary edge, trailing in the orbital direction, of a contact surface of the inner spiral end 24f of the spiral wall 24a to the base plate 36b, with which this spiral wall 24a sweeps over the outlet opening 42. In Fig. 6 it can be seen that the spiral wall 24a can therefore move significantly further compared to a circular opening with the same cross-sectional area, without the outlet opening 42 being opened to the upstream compressor chamber 38. Only at a time (i.e. a position of the spiral wall 24a) at which the discharge chamber 52 is almost "pumped empty" can a backflow into the upstream compressor chamber 38 occur. However, this significantly reduces the volume flow into the upstream compressor chamber 38 as well as the shock waves and the like.

[0064] Using an embodiment in which the outlet opening 42 is formed in a bore insert 60 (see Fig. 7-9), which in turn is (or will be) inserted into a corresponding bore in the base plate 36b of the F-scroll 36, a shape of the outlet opening 42 is described in more detail below.

[0065] Thus, the control edge 42a of the outlet opening 42 has a comparatively flat, curved curvature on the inlet side (i.e., on the side of the discharge chamber 52). The opposite trailing edge 42b has a comparatively more curved curvature. The outlet opening 42 thus has a profile on the inlet side that resembles a biconvex lens. The thickness of the lens is selected in the present embodiment such that the outlet opening 42 is not completely covered by the spiral wall 24a before the outer contour 24e releases the control edge 42a to the upstream compression chamber 38. This does result in a backflow from the discharge chamber 52 into the compression chamber 38.However, this backflow occurs at a significantly later point in time (i.e., positioning the O-Scroll 24 closer to the "end" or "turning point" of the orbital movement path) than in the case of a conventional, circular bore serving as the outlet opening. The latter is clearly evident here from the fact that the outlet opening 42 is formed in the circular-cylindrical bore insert 60. The accepted backflow represents a compromise with the largest possible cross-sectional area of ​​the outlet opening 42, thus enabling the highest possible volume flow through the outlet opening 42.

[0066] As can be seen in Fig. 9, the trailing edge 42b has a chamfer 62 (or rounding) on ​​the inlet side. The control edge 42a, on the other hand, is provided with a sharp edge, which, in conjunction with the spiral wall 24a, enables an improved sealing effect and, in particular, the latest possible opening to the upstream compressor chamber 38.

[0067] On the outlet side, however, the outlet opening 42 is (asymmetrically) widened in a diffuser-like manner (see Fig. 9). This results in a throttling effect on the refrigerant flowing through the outlet opening 42, reducing its flow velocity. This, in turn, can reduce the valve lift of the reed valve 46. Reducing the valve lift contributes to noise reduction.

[0068] Fig. 10 shows an alternative embodiment of the F-scroll 36. Here, the F-scroll 36 is designed as an aluminum die-cast part, as in the embodiment described above. The outlet opening 42 is molded directly into the base plate 36b. The aluminum die-casting process has the advantage that only a small casting skin forms and the molding accuracy is very high. This allows the outlet opening 42 to be formed by casting without the need for any further processing. Machining the free-form geometry of the outlet opening 42 shown in Figs. 9 and 10, on the other hand, would be comparatively complex. In particular, compared to the embodiment according to Fig. 6, the trailing edge 42b can be reshaped over a larger area of ​​the inner contour 36e of the adjacent spiral wall 36a and positioned along this "contour-following". This allows a dead volume in the ejection chamber 52 to be further reduced.

[0069] Another embodiment, here of the O-scroll 24, is shown in Fig. 11. The design of the outlet opening 42 corresponds to Figs. 5-9. Here, the spiral wall 24a of the O-scroll 24 has a recess or "wall thickness taper 64" on the radial inside, i.e. on the inner wall side 24g opposite the outer contour 24e. This recess is formed on a wall head end (or "free wall edge") facing the base plate 36b of the F-scroll 36 and extends only over a portion of the wall thickness and only a portion of the height of the spiral wall 24a. Furthermore, the wall thickness taper 64 is only formed in the above-described angular range of the spiral angle SW with which the spiral wall 24a sweeps over the outlet opening 42. As a result, the open area of ​​the outlet opening 42 can be kept as large as possible, with the compromise that backflow is possible over a longer movement distance of the O-scroll 24.However, a larger volume flow can also be delivered from the discharge chamber 52 for a correspondingly longer period. Alternatively, the recess described above can also be arranged in a base region of the spiral wall 36a of the F-scroll 36, with the outlet opening 42 partially pushed "under" the spiral wall 36a. This, in turn, can further delay the time of the backflow and / or increase the cross-sectional area. In both cases, however, the use of the recesses results in a somewhat larger dead volume, since fluid cannot be displaced in the area of ​​the respective recess.

[0070] In a further embodiment not shown, the outlet opening 42 is designed asymmetrically and extends along a base edge of the spiral wall 36a (between base plate 36b and spiral wall 36a) to the inner end of the spiral wall 36a and partially around it. This allows a complete emptying of the discharge chamber 52 to be achieved. This contributes to the smoothest possible running of the O-scroll 24, since in the event of a premature closure of the discharge chamber 52 towards the outlet opening 42, the O-scroll 24 has a residual volume which, as the spiral wall 24a continues to move along the spiral wall 36a, is further compressed and the refrigerant must escape through gaps between the spiral walls 24a and 36a, which often leads to a slight tilting of the

[0071] O-Scrolls 24 and thus can also lead to noise.

[0072] The subject matter of the invention is not limited to the exemplary embodiments described above. Rather, further embodiments of the invention can be derived by those skilled in the art from the above description.

[0073] In particular, the individual features of the invention and their embodiment variants described with reference to the various embodiments can also be combined with one another in other ways.

[0074] List of reference symbols

[0075] 2 scroll compressors

[0076] 4 Drive module

[0077] 6 Compressor module

[0078] 8 Interface

[0079] 10 Flange connection

[0080] 12 drive housing

[0081] 12a Motor housing

[0082] 12b Housing cover

[0083] 12c electronics housing

[0084] 13 Electric motor

[0085] 13a Rotor

[0086] 14 Engine electronics

[0087] 16 connection section

[0088] 18 Entrance

[0089] 20 Outlet

[0090] 22 Compressor housing

[0091] 24 O-Scroll

[0092] 24a Spiral wall

[0093] 24b base plate

[0094] 24d spiral corridor

[0095] 24e outer contour

[0096] 24f spiral end

[0097] 24g wall inside

[0098] 26 Swing Link

[0099] 28 shaft journals

[0100] 30 Motor shaft

[0101] 31 Counterweight

[0102] 32, 34 rolling bearings

[0103] 36 F-Scroll

[0104] 36a Spiral wall

[0105] 36b Base plate 36c Boundary wall

[0106] 36d spiral corridor

[0107] 36e inner contour

[0108] 36f spiral end

[0109] 38 Compressor chamber 0 Backpressure chamber

[0110] 42 Outlet opening

[0111] 42a Control edge

[0112] 42b trailing edge

[0113] 44 bore

[0114] 45 High pressure chamber

[0115] 46 Flapping valve

[0116] 48 valve lift limiters

[0117] 50 valve reeds

[0118] 52 Ejection chamber

[0119] 60 bore insert

[0120] 62 chamfer

[0121] 64 Wall thickness reduction

[0122] SW spiral angle

[0123] P contact point

Claims

Claims 1. Scroll machine (2) for conveying a fluid, in particular a refrigerant of a vehicle air conditioning system, comprising - a first, fixed, scroll (36) with a first base plate (36b) and a first spiral wall (36a) projecting from the first base plate (36b) and forming a first spiral path (36d), and - a second, orbitable scroll (24) with a second base plate (24b) and with a second spiral wall (24a) projecting from the second base plate (24b), which engages in the first spiral flight (36d) of the first scroll (36) and forms a number of delivery chambers (38, 50) with the first spiral wall (36a), wherein an outlet opening (42) is formed in a central region of the first base plate (36b), through which outlet opening, during normal operation, the delivered fluid escapes into a high-pressure chamber of the scroll machine (2) arranged rearwardly of this base plate (36b), wherein the outlet opening (42) is defined at least on the inlet side by a control edge (42a), which is first swept over by the second spiral wall (24a) during normal compression operation and whose curvature is aligned with a radially outwardly facing outer contour (24e) of the second spiral wall (24a). is approximated, and a trailing edge (42b) is limited,whose curvature is at least partially approximated to a radially inwardly facing inner contour (36e) of the first spiral wall (36a) and which is arranged closer to an inner spiral end (36f) of the first spiral wall (36a) than the control edge (42a)., 2. Scroll machine (2) according to claim 1, wherein the curvature of the control edge (42a) is approximated to the outer contour (24c) of the second spiral wall (24a) in a range of a spiral angle (SW) between 0 and 150 degrees, in particular between 20 and 130 degrees.

3. Scroll machine (2) according to claim 1 or 2, wherein the control edge (42a) has the same curvature as the outer contour (24c) of the second spiral wall (24a).

4. Scroll machine (2) according to one of claims 1 to 3, wherein the outlet opening (42) has an inlet chamfer (62) in the region of the trailing edge (42b), but is formed with comparatively sharp edges in the region of the control edge (42a).

5. Scroll machine (2) according to one of claims 1 to 4, wherein the second spiral wall (24a) has a wall thickness taper (64) in the region of a wall head end facing away from the second base plate (24b) from a wall inner side (24g) facing the outlet opening (42) and in the region with which the second spiral wall (24a) sweeps over the outlet opening (42) in the intended compression operation.

6. Scroll machine (2) according to one of claims 1 to 5, wherein the outlet opening (42) is widened in a diffuser-like manner on the outlet side.

7. Scroll machine (2) according to claim 6, wherein the diffuser-like extension of the outlet opening (42) has an opening angle of equal to or less than 30 degrees, in particular between 20 and 30 degrees.

8. Scroll machine (2) according to one of claims 1 to 7, wherein the outlet opening (42) is formed in a bore insert (60) manufactured separately from the first base plate (36b).

9. Scroll machine (2) according to one of claims 1 to 8, wherein the first scroll (36) is formed at least partially in an aluminum die-casting process, and wherein the outlet opening (42) is produced in the aluminum die-casting process by casting technology, and in particular without any post-processing.

10. Scroll machine (2) according to one of claims 1 to 9, wherein the outlet opening (42) is recessed on the outlet side in a rear side of the first base plate (36b), in particular in a step-like manner.

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