Spiral compressor with optimized contact pressure

Abstract

Spiral compressor for compressing a fluid with a stationary disk (1) with a stationary spiral (2), wherein the stationary spiral (2) is arranged on a stationary base (3) of the stationary disk (1) and forms a spiral compressor channel (6) extending from an outer end (5) of the stationary spiral (2) to an outlet opening (7) for the compressed fluid at an inner end (4) of the stationary spiral (2), wherein the stationary spiral (2) has a spiral angle (9) of more than 450°; an orbiting disk (11) with an orbiting spiral (12), wherein the orbiting spiral (12) is arranged on an orbiting base surface of the orbiting disk (11), wherein the orbiting disk (11) is orbitable relative to the stationary disk (1) along a compression direction (100), furthermore, the orbiting spiral (12) and the stationary spiral (2) are arranged nested within each other in such a way that at least two compression spaces (20a, 20a', 20a'', 20b, 20b') are bounded by the stationary base (3) and the stationary spiral (2) as well as by the orbiting base (12) and the orbiting spiral, wherein each of the compression chambers (20a, 20a', 20a'', 20b, 20b') moves from an intake area of ​​the compressor channel (6) to an outlet area of ​​the compressor channel (6) and thereby reduces its volume as the orbiting disk (11) orbits relative to the stationary disk (1) along the compression direction (100); an outlet pressure chamber (30) which is in fluid communication with the outlet opening (7); a pressure chamber (40) which is subjected to a pressure during compression operation, wherein the orbiting disk (11) is pressed against the stationary disk (1) by the pressure; a return connection (33) which forms a fluid connection from the outlet pressure chamber (30) to the contact pressure chamber (40); a reference aperture (50); and a reference connection (51) which forms a fluid connection between the pressure chamber (40) and the reference opening (50) to influence the pressure by means of a reference pressure applied to the reference opening (50) during compression operation, characterized in that the reference opening (50) is arranged in the stationary base area (3) within the compressor channel (6) such that, during compression operation, the reference opening (50) is swept twice by the orbiting spiral (11) during one revolution of the orbiting disk (11) and is in direct fluid communication with a final stage compression chamber (20a, 20a', 20a'') for a first part of the time required for the revolution and with a penultimate stage compression chamber (20b, 20b') for a further part of the time required for the revolution, and wherein the reference opening (50) in the compressor channel (6) is arranged at a position angle (54) from the inner end (4) of the stationary spiral (2) which is at least 315° / (0.5 · spiral angle / 360°) 0,1 and a maximum of 435° * (0.5 · spiral angle / 360°) 0,2 amounts.

Description

[0001] The invention relates to a spiral compressor for compressing a fluid.

[0002] Scroll compressors typically consist of a stationary disk with a stationary spiral and an orbiting disk with an orbiting spiral. The scroll compressor compresses a fluid—especially a gas—by having the orbiting disk rotate relative to the stationary disk. For this purpose, the orbiting spiral and the stationary spiral are nested within each other, forming compression chambers for the gas. Relative to the stationary spiral, each compression chamber, containing the gas, moves from an outer region of the stationary spiral to its center. As it moves, the space available for the gas decreases, and the gas is compressed. The orbiting disk with its orbiting spiral and the stationary disk with its stationary spiral together form a compressor unit.

[0003] The gas enters the compressor unit at an intake pressure and is expelled from it at a significantly higher outlet pressure.

[0004] Scroll compressors are used, for example, as compressors in air conditioning systems, especially in automotive air conditioning systems. They are also used as heat pumps. Compared to other compressor types, they are characterized by particularly smooth, low-vibration, and quiet operation.

[0005] The gas in the compressor unit, which is increasingly compressed within the scroll compressor, forces the orbiting disk and the stationary disk apart. This creates a lifting force on the orbiting disk. The magnitude of this lifting force depends primarily on the intake pressure, the discharge pressure, and the geometry of the compressor unit. The strength of the lifting force is determined by both the intake and discharge pressures, with the intake pressure having the greater influence.

[0006] To ensure that the orbiting disk is pressed firmly and tightly against the stationary disk and no gas escapes from the compressor unit, the orbiting disk is subjected to a contact pressure on its side opposite the stationary disk. This contact pressure pushes the orbiting disk towards the stationary disk with a force. This force counteracts the lifting force and must be greater than the latter. Otherwise, the lifting force would push the orbiting disk away from the stationary disk.

[0007] In conventional scroll compressors, the difference between the contact pressure and the intake pressure is always the same during compression operation, or more precisely, independent of the intake and outlet pressures. This difference must be large enough to ensure that the contact force acting on the orbiting disc is sufficient, even at maximum intake and outlet pressures, to reliably press the orbiting disc against the stationary disc for a tight seal.

[0008] A common method for adjusting the contact pressure is to pressurize a pressure chamber and limit the pressure relative to the intake pressure using a pressure control valve. The pressure control valve opens a fluid connection between the pressure chamber and an area with the intake pressure when the contact pressure exceeds the intake pressure plus a desired difference (for example, approximately 0.3 MPa). Pressurizing the pressure chamber simultaneously ensures that the contact pressure does not fall below this setpoint.

[0009] Since the lifting force opposing the contact pressure decreases non-linearly with lower intake pressure, a higher contact pressure and thus a higher contact force acts on the orbiting disc than would be necessary in most operating conditions. This leads to increased friction of the moving orbiting disc. Electrically driven scroll compressors typically operate in a speed range of 500 to 12,000 rpm. -1 High friction manifests itself through reduced efficiency.

[0010] German patent application DE 10 2013 020 762 A1 discloses a scrolling machine with a lifting device that can be controlled and regulated by means of a control unit. This device allows an eccentric disk of the scrolling machine to be subjected to a contact force opposite to the contact force, or it allows the contact force to be reduced. The lifting device is designed as a 2 / 3-way valve. Opening the valve equalizes the pressure in the back pressure chamber with the pressure in a low-pressure chamber. By selectively controlling the valve, the frictional force between the eccentric disk and a stator disk can be minimized. However, this solution is complex and expensive because the controllable 2 / 3-way valve and the additional control unit are required. Furthermore, energy is lost unused during the pressure equalization when the valve opens.

[0011] In the spiral compressor described in publication JP 2014-031 795 A, an orbiting disk is pressed against a stationary disk by a contact pressure, which lies between an intake pressure and an outlet pressure. A difference between the outlet pressure and the contact pressure causes oil to flow from an oil reservoir into a longitudinal bore in a drive shaft. Some of the oil is routed from the drive shaft to a first bearing for lubrication. This portion of the oil then flows into a pressure chamber. Another portion of the oil flows from the drive shaft into an orbiting bearing chamber. The orbiting bearing chamber serves, among other things, to press the orbiting disk against the stationary disk using the outlet pressure. The pressure chamber also serves to press the orbiting disk against the stationary disk using the contact pressure.The oil flowing through the first bearing into the pressure chamber is still almost at the outlet pressure and consequently pressurizes the pressure chamber. It lubricates an Oldham ring and then flows through a compression chamber passage into a compression chamber and through an intake passage into the intake of the scroll compressor. This maintains the contact pressure at a moderate level. A pressure relief valve in the compression chamber passage opens when the contact pressure exceeds the pressure in the compression chamber. This device is also complex and expensive, as it requires the compression chamber passage with the pressure relief valve, the intake passage, and, in addition to the intake pressure chamber, the orbiting bearing chamber. Furthermore, the actual contact force of the orbiting disk is influenced by many different factors and cannot be specifically adjusted for different operating conditions.

[0012] In a scroll compressor known from DE 10 2017 110 913 B3, a passage in the form of a through-hole, running essentially perpendicular to the base, is formed in the base of a displacement spiral. The passage is located in a central section of the displacement spiral and off-center between the spiral flank sections. The passage temporarily establishes a fluid connection between a back pressure chamber and a compression chamber.

[0013] DE 101 47 339 A1 discloses a further spiral compressor. A connecting passage is formed by a base plate of a movable spiral element, which orbits relative to a stationary spiral element. A compression chamber and an intermediate pressure chamber are connected via the connecting passage for a predetermined duration of the compression cycle.

[0014] Other spiral compressors are known, for example, from DE 10 2013 020 762 A1, DE 10 2017 105 175 B3, EP 2 474 740 A1, US 2012 / 0 230 854 A1, US 2013 / 0 216 416 A1 and JP 2014- 031 795 A.

[0015] The object of the present invention is to create a simple spiral compressor that is easier to manufacture and economical, and that operates efficiently in various operating conditions.

[0016] The above problem is solved by a spiral compressor for compressing a fluid with the features of claim 1.

[0017] The spiral compressor includes, among other things... a stationary disk with a stationary spiral, wherein the stationary spiral is arranged on a stationary base surface of the stationary disk and forms a spiral compressor channel extending from an outer end of the stationary spiral to an outlet opening for the compressed fluid at an inner end of the stationary spiral; an orbiting disk with an orbiting spiral, wherein the orbiting spiral is arranged on an orbiting base surface of the orbiting disk, wherein the orbiting disk is orbitable relative to the stationary disk along a compression direction, furthermore, the orbiting spiral and the stationary spiral are arranged nested within each other in such a way that at least two compression spaces are bounded by the stationary base and the stationary spiral as well as by the orbiting base and the orbiting spiral, wherein the compression chambers shift from an intake area of ​​the compressor channel to an outlet area of ​​the compressor channel, thereby reducing its volume as the orbiting disk orbits relative to the stationary disk along the compression direction; an outlet pressure chamber that is in fluid communication with the outlet opening; a pressure chamber which is subjected to a pressure during compression operation, whereby the orbiting disk is pressed against the stationary disk by the pressure; a return connection that forms a fluid connection from the outlet pressure chamber to the contact pressure chamber; a reference opening located in the stationary base area within the compressor channel; and a reference connection that forms a fluid connection between the pressure chamber and the reference opening to influence the pressure based on a reference pressure applied to the reference opening during compression operation.

[0018] The intake and outlet pressures during compression operation are typically determined by a system connected to the scroll compressor, through which the fluid compressed in the compressor flows. Such a system could, for example, be a heat exchanger in an air conditioning system. The compressed fluid can be discharged from the scroll compressor's outlet pressure chamber, for example, through the outlet connection and outlet port.

[0019] The outlet pressure is present at the outlet port, and the intake pressure at the intake port. Preferably, the outlet pressure chamber, the contact pressure chamber, the orbiting disk, the stationary disk, the return connection, and the reference connection are arranged within the intake pressure chamber. This ensures that all these components are securely enclosed by the intake pressure chamber. In this case, the intake port and the outlet port can be located on the intake pressure chamber, with the outlet port forming a pressure-tight fluid connection with the outlet pressure chamber.

[0020] The maximum outlet pressure of a scroll compressor results from the geometry of the compressor unit (the nested stationary and orbiting disks) and the respective intake pressure. The higher the intake pressure, the higher the maximum outlet pressure. For a given intake pressure, the maximum outlet pressure is determined by the compression of the fluid achievable within the compressor unit's geometry, using known fluid equations, such as the ideal gas law or the van der Waals equation.

[0021] The (actual) outlet pressure is generally lower than the maximum outlet pressure. Once the outlet pressure – specified, for example, by the connected system – is reached, the scroll compressor no longer compresses the fluid but pushes it out of the compressor unit through the outlet opening into the outlet pressure chamber. A check valve (such as a non-return valve or check flap) may be installed at the outlet opening. This prevents fluid from flowing back out of the outlet pressure chamber through the outlet opening if the outlet pressure in the outlet pressure chamber is higher than the pressure at the outlet opening in the compressor unit.

[0022] With the present invention, the contact pressure is directly influenced by the reference pressure. For a given position of the reference opening in the compressor channel, the reference pressure depends strongly on the intake pressure and, potentially, also on the outlet pressure. Therefore, any difference between the contact pressure and the intake pressure automatically adjusts to the operating condition of the scroll compressor. A complex, external, failure-prone, and expensive contact pressure control system is not required. In particular, no actively variable pressure control valve is needed for setting and regulating the contact pressure. Through the interaction of the return line and the reference line, a pressure equilibrium is established in the contact pressure chamber.If the contact pressure is greater than the reference pressure, fluid and / or oil flows from the contact pressure chamber through the reference connection and the reference port into the compressor unit, specifically into the compression chamber when it is in fluid contact with the reference port. This reduces the contact pressure. Conversely, fluid and / or oil from the outlet chamber or oil filter is fed into the contact pressure chamber via the return connection. This return increases the contact pressure, unless the pressure loss caused by the reference connection is greater than or equal to this. In simpler terms, the return connection supplies fluid and / or oil to the contact pressure chamber, while the reference connection and the reference port are used to adjust or regulate the contact pressure.The oil and / or fluid flowing into the compressor unit via the reference connection must be further compressed, but only from the contact pressure level up to the high pressure. The oil also contributes to its lubrication, if necessary. This improves the service life of the scroll compressor.

[0023] The reference pressure depends on the degree of fluid compression in the compressor unit when the compression chamber reaches and passes over the reference orifice. Changing the position of the reference orifice within the compressor channel generally alters the reference pressure at the orifice during compression operation, and consequently, the resulting contact pressure. In other words, the contact pressure can be determined by adjusting the position of the reference orifice.

[0024] Through the targeted design and coordination of the return connection, the reference connection, and the reference opening—particularly the precise positioning of the reference opening within the compressor channel—the automatic adjustment of various desired contact pressures for different operating conditions of the scroll compressor is achieved. Accordingly, the contact force with which the orbiting disc is pressed against the stationary disc is adjusted for different operating conditions to match the lifting force acting on the orbiting disc in the respective operating condition. In particular, a comparatively low contact force is applied when the contact pressure and / or the discharge pressure are low. This improves the efficiency of the scroll compressor when it is operating in such a condition. Furthermore, the start-up and acceleration of the scroll compressor is significantly facilitated by the operating-condition-dependent contact force.

[0025] Preferably, during compression operation, the contact force acting on the orbiting disk is at least 10 percent greater than the lifting force acting on the orbiting disk in every operating condition, and particularly preferably at least 15 percent greater. In this way, the orbiting disk is reliably pressed against the stationary disk, and no fluid can escape from the compressor unit.

[0026] Alternatively and / or additionally, in compression operation, the contact force acting on the orbiting disc is preferably a maximum of 30 percent greater than the lifting force acting on the orbiting disc, and particularly preferably a maximum of 20 percent greater, in every operating condition. This avoids unnecessarily high friction caused by excessive contact force. This enables energy-efficient operation of the spiral compressor in all operating conditions.

[0027] The contact force with which the orbiting disc is pressed against the stationary disc by the contact pressure depends on the effective area of ​​the orbiting disc upon which the contact pressure can act in the direction of the orbiting disc. Conversely, the lift-off force depends on the intake pressure, the outlet pressure, and the geometry of the compressor unit. Therefore, the design and configuration of the return connection, the reference connection, and the reference opening—especially their precise positioning within the compressor channel—which is necessary for achieving the desired ratio of contact force to lift-off force, can vary for different embodiments of the scroll compressor.

[0028] If the orbiting disk orbits relative to the stationary disk, this means, in other words, that the orbiting disk is displaced eccentrically along a circular path relative to the stationary disk. Preferably, the orbiting disk orbits along a circular path around a stationary central axis of the stationary disk, the stationary central axis being perpendicular to the stationary base and extending through a center of the stationary spiral.

[0029] The stationary spiral can be formed from a wall extending parallel to the stationary central axis away from the stationary base. Preferably, an end face of the stationary spiral facing away from the stationary base along the stationary central axis is flat and parallel to the stationary base.

[0030] The stationary spiral and the orbiting spiral each have one spiral arm.

[0031] The intake section of the compressor channel comprises all areas of the compressor channel that are at least temporarily in direct fluid contact with a fluid inlet when the orbiting disk orbits relative to the stationary disk along the compression direction. The fluid inlet – for example, in the form of the intake port – serves to supply the fluid to be compressed to the scroll compressor.

[0032] During compression operation, the fluid is compressed in the at least two compression chambers, moved towards the outlet opening and finally forced into the outlet opening.

[0033] The outlet area of ​​the compressor channel includes all areas of the compressor channel that are at least temporarily in direct fluid contact with the outlet opening for the fluid when the orbiting disk orbits relative to the stationary disk along the compression direction.

[0034] The central area of ​​the compressor channel includes all areas of the compressor channel that cannot be in direct fluid contact with either the inlet area or the outlet area.

[0035] In an advantageous embodiment of the invention, the reference orifice is arranged in the central region and / or in the outlet region of the compressor channel. Thus, the reference orifice is not located in the inlet region of the compressor channel. During operation of the scroll compressor, this prevents a direct fluid connection between the fluid inlet and the reference orifice, and no fluid can flow from the reference orifice directly into the suction region and / or the fluid inlet. Such an undesirable pressure loss would lead to a deterioration in the efficiency of the scroll compressor.

[0036] For the purposes of this application, the innermost turn or first turn of a spiral refers to a region of that spiral extending from its inner end to the point where it has once encircled its center. The inner end of the stationary spiral is assigned a position angle of 0°. This position angle increases continuously along the length of the stationary spiral to its outer end. The spiral angle of the stationary spiral is defined by its outer end. This spiral angle thus corresponds to the largest position angle of the stationary spiral.

[0037] This is explained using the example of a stationary spiral with two turns: The first turn of the stationary spiral begins at the inner end of the stationary spiral at a position angle of 0° and ends at a position angle of 360°. The second and outermost turn begins at a position angle of 360° and ends at a spiral angle of 720° at the outer end of the stationary spiral.

[0038] Position angles are defined accordingly within the compressor channel. An outer end of the spiral compressor channel is defined by an inlet opening of the compressor channel, which is formed between the outer end of the stationary spiral and the beginning of the outermost turn of the stationary spiral.

[0039] For the purposes of this application, the outside of a region of a spiral is the side of that region facing away from the center of the spiral in a radial direction. Similarly, the inside of a region of the spiral is the side of that region facing the center of the spiral in a radial direction.

[0040] It should be emphasized here that the definitions regarding the compressor channel are independent of the definition of the compression chamber. In particular, the compression chamber does not need to be completely within the compressor channel at all times. For example, the compression chamber can be formed by an outer end of the orbiting spiral coming into contact with an outer surface of the outermost turn of the stationary spiral. This seal closes and seals the compression chamber. If, on the other hand, the compression chamber is closed by an outer surface of the orbiting spiral coming into contact with the outer end of the stationary spiral, then the compression chamber is already completely within the compressor channel at that point.

[0041] The return line utilizes the high outlet pressure to pressurize the inlet pressure chamber. This pressure forces the orbiting disc against the stationary disc, ensuring a secure seal between the two discs and, in particular, a reliable seal within the compression chamber. The rear side of the orbiting disc, facing away from the orbiting base, can form part of the boundary of the inlet pressure chamber. Preferably, the return line runs directly from the outlet pressure chamber (or a component within the outlet pressure chamber) to the inlet pressure chamber. This simplifies the design and makes the spiral compressor easier to manufacture.

[0042] The reference pressure varies during operation of the scroll compressor, even during continuous compression. As soon as a new compression chamber reaches the reference opening, the reference pressure drops to the current pressure in that compression chamber. As the compression chamber continues to move towards the outlet opening and shrinks, the fluid pressure in the compression chamber, and thus the reference pressure, increases continuously. The reference pressure is at its maximum when the compression chamber just barely covers the reference opening. The reference opening is then swept over and covered, i.e., closed, by the orbiting spiral. A new compression chamber then reaches the reference opening, and the reference pressure decreases. Depending on the position of the reference opening, it can be swept over and covered by the orbiting spiral once or, according to the invention, twice during one revolution of the orbiting disk.

[0043] The volumes of the reference connection and the pressure chamber partially reduce and dampen the effect of these fluctuations. Furthermore, due to the typically high rotational speed of the orbiting disk, the fluctuations are very rapid, and essentially only a mean reference pressure can be considered. The mean reference pressure is calculated by dividing the integral of the reference pressure over the orbital period (the time required for one complete revolution) by this orbital period. Similarly, other mean pressures are defined as time-averaged values ​​over one revolution, in particular the mean pressure difference between the contact pressure and the intake pressure.

[0044] According to the invention, the spiral compressor has at least two compression chambers, wherein the reference opening is arranged in the compressor channel such that, during compression operation, the reference opening is in direct fluid contact with a compression chamber of the last stage for a first part of the time required for the revolution and with a compression chamber of the penultimate stage for a further part of the time required for the revolution. The first part and the further part together do not necessarily have to account for the entire time required for the revolution. Rather, there may be other parts as well.

[0045] This targeted positioning of the reference opening in the compressor channel ensures that even a high-pressure area of ​​the scroll compressor influences the contact pressure, and that the contact pressure remains sufficiently high in every operating condition during compression so that the contact force on the orbiting disc is adequately greater than the lifting force. This ensures that the orbiting disc is pressed tightly against the stationary disc in every operating condition during compression.

[0046] The last-stage compression chamber is characterized by the fact that, during compression, the fluid it contains is at least partially directed into the outlet opening within the current revolution of the orbiting disk. The penultimate-stage compression chamber is characterized by the fact that, during compression, the fluid it contains will be at least partially directed into the outlet opening within the next revolution of the orbiting disk. There can be multiple last-stage compression chambers and multiple penultimate-stage compression chambers. The penultimate-stage compression chamber(s) follow the last-stage compression chamber(s) in the compressor channel, in the opposite direction to the compression direction.

[0047] Within one revolution, the orbiting disk completes exactly one full rotation (i.e., 360°) relative to the stationary disk. The end of a revolution is defined by the operating point at which the fluid (especially refrigerant) is last discharged into the outlet. This marks the completion of one compression cycle. This operating point also defines the end of the final stage. The start of this final stage is defined as one full revolution of the orbiting disk around the stationary disk prior, i.e., 360° prior.

[0048] This is illustrated by the example of a scroll compressor that compresses the fluid in compression operation within two revolutions (of 720°) and delivers it to the discharge opening: The first and penultimate stage begins when a quantity of the fluid to be compressed has just been enclosed in the compression chamber. It ends after the first complete revolution (of 360°) of the orbiting disk around the stationary disk. Simultaneously, the second and final stage begins for the fluid currently contained in this compression chamber. The final stage ends with the second complete revolution (of 720°) of the orbiting disk, when the fluid has been completely delivered to the discharge opening.

[0049] The stationary spiral has a spiral angle of more than 425°, with the reference opening in the compressor channel being arranged at a position angle from the inner end of the stationary spiral that is at least 315° / (0.5⋅spiral angle / 360°)0.1 and maximum 435°*(0.5⋅spiral angle / 360°)0.2 is, preferably at least 345° / (0.5⋅spiral angle / 360°)0.1 and maximum 405°*(0.5⋅spiral angle / 360°)0.2

[0050] This positioning of the reference opening has proven particularly advantageous for achieving the aforementioned benefits of the invention. On the one hand, it ensures a sufficiently large influence of the high-pressure area near the outlet opening, preventing the contact pressure from becoming too low. On the other hand, the reference pressure in this area is still low enough that no unnecessarily high contact force acts on the orbiting disc. This benefits the efficiency of the spiral compressor.

[0051] As a general rule: the smaller the angle at which the reference port is positioned, the higher the mean reference pressure during compression. This is because the smaller the angle of the reference port, the closer it is to the outlet port. Consequently, the fluid in the compression chamber is more highly compressed when the compression chamber reaches the reference port.

[0052] In addition, the mean reference pressure generally depends on other factors, particularly the intake and exhaust pressures. Furthermore, for the same reference port angle, the mean reference pressure can also depend on whether the reference port is located further in or out radially within the compressor channel.

[0053] In a further development of the invention, the stationary scroll has at least 1.25 turns. This corresponds to a spiral angle of the stationary scroll of at least 450°. This ensures sufficient maximum compression of the scroll compressor for typical applications.

[0054] Alternatively and / or additionally, the stationary spiral preferably has a maximum of 2.5 turns. This corresponds to a spiral angle of the stationary spiral of a maximum of 900°. This keeps the spiral compressor compact, lightweight, and inexpensive to produce.

[0055] The stationary spiral particularly preferably has two turns, with the reference opening in the compressor channel arranged at a position angle from the inner end of the stationary spiral of at least 315° and at most 435°, most preferably at least 345° and at most 405°. This arrangement has proven to be particularly practical.

[0056] In a further development of the invention, in compression operation, the mean pressure difference between the contact pressure and an intake pressure increases with increasing intake pressure, if the outlet pressure remains at least substantially constant.

[0057] If the contact pressure and / or the outlet pressure increase, the lifting force on the orbiting disk also increases. To ensure the lowest possible contact force at low intake pressure and a sufficiently high contact force at high intake pressure, it is advantageous for the contact pressure to increase with increasing intake pressure.

[0058] In a further advantageous embodiment of the invention, the spiral compressor has a flow valve provided in the return line. The flow valve influences the effect of the return line. This facilitates the adjustment and setting of the contact pressure.

[0059] The flow control valve is preferably designed as a throttle valve. In this application, a throttle valve is understood to be an element that generates a pressure differential between the valve inlet and outlet (and does not throttle the mass flow). This significantly simplifies the adjustment of the contact pressure via the return line and the reference line. This increases the efficiency of the scroll compressor compared to designs without a throttle valve.

[0060] Preferably, a damping element is provided in the reference connection between the reference orifice and the pressure chamber. This damping element further dampens fluctuations in the reference pressure. The pressure is kept more stable and can be adjusted more precisely. This further improves the efficiency of the scroll compressor. Since the damping element handles at least a significant portion of the reference pressure damping, other parts of the reference connection can have a small cross-section. This avoids unnecessarily large fluid mass flows through the reference connection. For example, the reference connection can have a cross-sectional area that falls within one of the ranges proposed below for the reference orifice area.

[0061] The damping element is preferably designed as a damping chamber. Such a damping chamber can be manufactured particularly easily, quickly, and cost-effectively. The additional volume of the damping chamber between the reference opening and the contact pressure chamber dampens the amplitude of the reference pressure as described above.

[0062] The damping chamber has a volume of 5 cm³ that is highly preferred. 3 up to 6 cm 3 This size has proven particularly advantageous. On the one hand, the damping chamber is then large enough to sufficiently dampen fluctuations in the reference pressure to achieve the aforementioned benefits. On the other hand, it is still compact enough to require little space and can be easily integrated into the reference connection.

[0063] In a preferred embodiment of the invention, the reference opening in the stationary base surface has an opening area of ​​between 0.5 mm 2 and 8.05 mm 2 on, preferably between 1.13 mm 2 and 3.15 mm 2The reference opening must be large enough to allow for the desired influence of the reference pressure on the contact pressure through a sufficiently rapid and strong fluid exchange between the contact pressure chamber and the compression chamber passing over the reference opening. However, the reference opening must not be so large that it is completely closed by the orbiting spiral when the spiral passes over it. Otherwise, two consecutive compression chambers could come into fluid contact with each other via the reference opening, potentially leading to an undesirable pressure equalization between them. Furthermore, the reference opening and the reference connection should have the smallest possible cross-section.

[0064] This prevents unnecessary fluid movement, compression, and subsequent expansion within the reference connection during compression operation due to fluctuations in the reference pressure. A smaller cross-section of the reference orifice and / or the reference connection therefore improves the efficiency of the spiral compressor.

[0065] In a particularly advantageous embodiment of the invention, the reference opening in the stationary base surface is designed as a round hole with a diameter between 0.4 mm and 1.6 mm, preferably between 0.6 mm and 1.0 mm. Such a hole can be produced quickly, easily, and with good reproducibility by drilling. The aforementioned cross-sections for the reference opening and the corresponding advantages are thus achieved particularly easily.

[0066] In a further development of the invention, the spiral compressor has an oil separator in the outlet pressure chamber and an oil reservoir, wherein the return connection leads from the oil reservoir to the contact pressure chamber.

[0067] The oil serves to lubricate and protect the orbiting and stationary disks, which move relative to each other during compression. However, some of the oil escapes through the outlet opening into the discharge pressure chamber. The oil separator ensures that this oil is separated and collected in the oil reservoir. This prevents oil from leaving the scroll compressor and entering any connected system, such as a heat exchanger. The oil would otherwise contaminate the heat exchanger from the inside and impair heat transfer.

[0068] The oil separator allows at least some of the separated oil to be returned via the return line. The oil, or a portion thereof, can then be reintroduced into the compressor unit through the reference connection and the reference port. This reuse ensures its lubrication and protection. Oil recirculation thus improves the efficiency and reliability of the scroll compressor.

[0069] Preferably, the reference connection between the pressure chamber and the reference opening is always permeable in both directions. This ensures that the reference opening and the pressure chamber are always in unimpeded fluid communication via the reference connection.

[0070] The contact pressure is adjusted by the reference opening and the reference connection depending on the operating conditions, without the need for additional mechanical components such as flaps or valves to regulate fluid flow in the reference connection. The proposed system is therefore particularly cost-effective and reliable.

[0071] In a particularly preferred embodiment of the invention, no valve is provided in the reference connection.

[0072] With the present invention, the selected position of the reference opening in the compressor channel eliminates the need for a valve in the reference connection. This allows for particularly simple and cost-effective production of the reference connection. Eliminating the valve results in a lighter scroll compressor. Furthermore, such a scroll compressor is more reliable, as the valve would represent a potential source of failure.

[0073] In a further advantageous embodiment of the invention, a pressure control valve is provided in the reference connection, which closes the fluid connection between the contact pressure chamber and the reference opening when the reference pressure is at least 0.2 bar greater than the contact pressure, preferably at least 0.8 bar.

[0074] Due to the pressure control valve, no pressure equalization or fluid flow through the reference connection occurs when the reference pressure reaches or exceeds the specified level. The pressure control valve prevents the contact pressure from becoming too high when the reference pressure is very high. Excessive contact pressure is detrimental because it increases friction. In particular, the pressure control valve prevents pressure spikes in the reference pressure from damaging the axial sealing surface of the orbiting disc. Furthermore, it offers additional possibilities for regulating the contact pressure. The reference port can be positioned closer to the outlet port in the compressor channel, i.e., at a smaller angle, without resulting in an undesirably high contact pressure.

[0075] If both the pressure control valve and the damping element are provided in the reference connection, the damping element is particularly preferably arranged between the reference orifice and the pressure control valve. This reduces the pressure control valve's exposure to strong pressure fluctuations. This allows the use of a more sensitive pressure control valve and a more precise adjustment of the pressure differential between the contact pressure and the mean reference pressure. Furthermore, the number of opening and closing cycles of the pressure control valve during operation is reduced, as is the damping of the reference pressure, especially its extremes. This increases the service life of the pressure control valve and the reliability of the scroll compressor.

[0076] Preferably, the scroll compressor incorporates an electric motor to drive the orbiting disk. Integrating the electric motor into the scroll compressor enables particularly precise and efficient operation. The operation of the electric motor can be precisely tailored to the specific scroll compressor. In particular, the drive of the scroll compressor is then independent of the operating state of other, external components. Most preferably, the electric motor is arranged within the intake chamber.

[0077] Alternatively and / or additionally, the scroll compressor may also include a power transmission device for driving the orbiting disk via an external drive unit. The external drive unit may be, for example, an internal combustion engine. The power transmission device may include a clutch (such as a magnetic clutch).

[0078] Optionally, the scroll compressor can also be used in a heat pump system, for example. This is particularly interesting for the air conditioning of electric vehicles and / or full hybrid vehicles.

[0079] The invention further relates to an air conditioning system with a scroll compressor according to the invention. In particular, it can be an air conditioning system for a motor vehicle.

[0080] The described design options and advantages for the scroll compressor apply accordingly to the system.

[0081] In a further development of the invention, the air conditioning system comprises a refrigerant which is compressed by the spiral compressor in compression operation, wherein the refrigerant is supplied with an intake pressure p s is drawn into the spiral compressor and operates the spiral compressor with an outlet pressure p dexits, and wherein the reference opening is arranged in the compressor channel such that the following conditions are established during the compression operation of the spiral compressor: • a first quotient Q1, defined by a contact pressure p b,max , if the intake pressure p s,max a vaporization pressure p v,max of the refrigerant at a temperature of 15.7 °C, divided by a contact pressure p b,m i n , if an intake pressure p s,min a vaporization pressure p v,min the refrigerant's coefficient of performance at a temperature of -26.4 °C lies in a range of 2.4 to 4 (that is: 2.4≤Q1=pn,max(ps,max=pv,max(15.7°C)) / pb,min(pn,min=pv,min(−26.4°C))≤1.4); • a second quotient Q2, defined by the contact pressure p b,max , if the outlet pressure p d,max a condensation pressure p c,max the refrigerant at a temperature of 72.6 °C, divided by a contact pressure Pb,min , if an outlet pressure p d,min a condensation pressure p c,min The refrigerant's coefficient of performance at a temperature of 34.4 °C is in the range of 1.1 to 1.4 (that is: 1.1≤Q2=pb,min(pd,max=pc,max(72.6°C)) / pb,min(pd,min=pc,min(34.4°C))≤1.4): • The product of the first quotient Q1 with the second quotient Q2 lies in a range of 2.6 to 5.6 for an operating range of the spiral compressor (that is: 2.6 ≤ Q1 · Q2 ≤ 5.6, if pv,min(−26.4°C)≤ps≤pv,max(15.7°C) and on the other hand pc,min(34.4°C)≤pd≤pc,max(72.6°C)).

[0082] This ensures sufficient adjustment of the contact pressure depending on the respective operating state of the air conditioning system. The intake pressure p s and the outlet pressure p d are essentially determined by a temperature-dependent evaporation pressure p v and a temperature-dependent condensation pressure pc the refrigerant is determined. The temperatures of the refrigerant at an intake port of the scroll compressor and at an outlet port of the scroll compressor, in turn, depend on the temperature of the area to be cooled and the temperature of an environment to which heat is to be transferred.

[0083] For a particularly preferred air conditioning system using the refrigerant R134a, the following values ​​apply as an approximation: pv,min(−26.4°C)=0.1 Mpa, pv,max(15.7°C)=0.5 Mpa, pc,min(34.4°C)=1.0 MPaand pc,max(72.6°C)=2.5 Mpa.

[0084] In general, other fluorinated refrigerants can also be used, for example, R1234yF. The relevant pressure values ​​for fluorinated refrigerants are typically in the range of 0.1 to 3 MPa. The use of other refrigerants is also possible, for example, R744 (CO2, pressure values ​​typically in the range of 2.0 to 13.0 MPa) or butane.

[0085] The invention is explained below with reference to exemplary embodiments and the figures. All features described and / or illustrated, individually or in any combination, constitute the subject matter of the invention, even independently of their compilation in the claims or their cross-references.

[0086] They show schematically: Fig. 1 a first embodiment of a spiral compressor according to the invention in a longitudinal section; Fig. 2 a second embodiment of a spiral compressor according to the invention, which, in contrast to the first embodiment, consists of Fig. 1 has a damping chamber in a reference joint, in a longitudinal section; Fig. 3A a cross-section through a compressor unit of a spiral compressor according to the invention with a stationary spiral with 2.25 turns, after an orbiting disk has completed one revolution around the stationary disk to one eighth; Fig. 3B the cross-section from Fig. 3B, after the orbiting disk has completed one quarter of its revolution around the stationary disk; Fig. 4A a top view of an embodiment of a stationary disk of a spiral compressor according to the invention, looking towards the stationary spiral and a stationary base surface of the stationary spiral, wherein the stationary spiral has two turns; Fig. 4B the supervision from Fig. 4A with highlighted representation of the in Fig. 4A shown angle.

[0087] During a Fig. In the first embodiment of a spiral compressor according to the invention for compressing a refrigerant, as shown in Figure 1, a stationary disk 1, an orbiting disk 11, an outlet pressure chamber 30, a contact pressure chamber 40, and an electric motor 70 are arranged within an intake pressure chamber 60. The electric motor 70 has a rotor 71 and a stator 72 and is connected to an inverter 80, which is provided outside the intake pressure chamber 60.

[0088] The intake pressure chamber 60 is provided with an intake port 61 and an outlet port 62, via which the spiral compressor can be connected to an external air conditioning system, for example, a heat exchanger of a vehicle air conditioning system. The outlet port 62 is in pressure-tight fluid communication with the outlet pressure chamber 30 via an outlet connection 63.

[0089] The stationary disk 1 and the orbiting disk 11 are nested within each other to form a compressor unit. The stationary disk 1 faces the outlet pressure chamber 30, while the orbiting disk 11 faces the intake pressure chamber 40. The compressor unit is connected to the outlet pressure chamber 30 via an outlet opening 7. A check valve 8 prevents refrigerant from flowing back from the outlet pressure chamber 30 into the compressor unit.

[0090] The outlet pressure chamber contains an oil separator 31 and an oil reservoir 32. A return connection 33 leads directly from the oil reservoir 32 to the pressure chamber 40. This return connection 33 establishes a fluid connection between the outlet pressure chamber 30 and the pressure chamber 40. A throttle valve 34 in the return connection 33 creates a pressure differential between the outlet pressure in the outlet chamber 30 and the pressure applied to the pressure chamber 40.

[0091] The pressure chamber 40 is simultaneously connected via a reference connection 51 to a reference opening in a stationary base surface (in Fig. (1 not shown) of the stationary disk 1 in connection.

[0092] During compression operation, the exhaust pressure chamber 30 has an exhaust pressure that is located at the exhaust port 62, and the intake pressure chamber 60 has an intake pressure that is located at the intake port 61 and is lower than the exhaust pressure.

[0093] The refrigerant enters the intake pressure chamber 60 through the intake port 61 at intake pressure and is drawn in by the compressor unit. In compression chambers (in Fig. (1 not shown), which are formed in the compressor unit between the stationary disk 1 and the orbiting disk 11, the refrigerant is compressed until it reaches the outlet pressure. It is then conveyed through the check valve 8 and the outlet opening 7 into the outlet pressure chamber 30.

[0094] In the outlet pressure chamber 30, the oil separator 31 separates the oil carried in the refrigerant. The separated oil is collected in the oil reservoir 32. The oil-free, compressed refrigerant, now at outlet pressure, is discharged from the outlet pressure chamber 30 through the outlet connection 63 and the outlet port 62 from the scroll compressor.

[0095] The refrigerant, enclosed and increasingly compressed in the compression chambers, exerts a lifting force on the orbiting disk 11. Without a counterforce, this lifting force would push the orbiting disk 11 away from the stationary disk 1. The two disks would then no longer seal against each other, and the compression chambers would no longer be sealed. The refrigerant could escape from the compressor unit into the intake pressure chamber 60. To prevent this, a contact pressure is maintained in the pressure chamber 40 during compression operation, which presses the orbiting disk 11 against the stationary disk 1 with a contact force. This ensures that the orbiting disk 11 is pressed securely and tightly against the stationary disk 1.

[0096] Fig. Figure 2 shows a second embodiment of a spiral compressor according to the invention. The second embodiment corresponds to the first embodiment with the sole difference that, in addition to the first embodiment, a damping chamber 52 is provided in the reference connection 51. The volume of the damping chamber 52 is 5 cm³. 3 up to 6 cm 3 This additional volume in the reference connection 51 dampens fluctuations in the reference pressure at a reference orifice (in Fig. 2 not shown). Accordingly, the contact pressure is kept more stable and the orbiting disk 11 is pressed more evenly against the stationary disk 1.

[0097] In Fig. 3A is a cross-section through a compressor unit of a spiral compressor according to the invention, for example the spiral compressor made of Fig. 1 or Fig. 2, shown. Accordingly, the same reference symbols are used for identical features. An intersection surface for Fig. 3A lies between the orbiting disk 11 and the stationary disk 1 in Fig. 1 or Fig. 2 and extends parallel to a stationary base 3 of the stationary disk 1. A stationary spiral 2 with 2.25 turns is arranged on the stationary base 3. Accordingly, an outer end 5 of the stationary spiral 2 is arranged at a spiral angle of 810° from an inner end 4 of the stationary spiral 2.

[0098] Due to the cross-section of the orbiting disk 11, Fig. Figure 3A shows only one orbiting spiral 12, which is arranged on an orbiting base (not shown) of the orbiting disk 11. The orbiting spiral 12 has 2.25 turns (like the stationary spiral 2).

[0099] The stationary disk 1 and the orbiting disk 11 are nested within each other. During compression operation, the orbiting disk 11 is held in place by the contact pressure in the contact pressure chamber 40 (see Fig. 1 and Fig. 2) pressed against the stationary disk 1. As a result, on the one hand, an end of the orbiting spiral 12 facing away from the orbiting base surface is in close contact with the stationary base surface 3, and on the other hand, an end of the stationary spiral 2 facing away from the stationary base surface 3 is in close contact with the orbiting base surface. The stationary base surface 3, the stationary spiral 2, the orbiting base surface, and the orbiting spiral 12 thus define several compression spaces. In the Fig. In the position of the orbiting disk 11 or the orbiting spiral 12 shown in 3A, a final stage compression chamber 20a, 20a', 20a'' and two penultimate stage compression chambers 20b, 20b' are thus defined in a compressor channel 6, which is formed between the turns of the stationary spiral 2, wherein the final stage compression chamber 20a, 20a', 20a'' is formed from a first sub-section 20a, a second sub-section 20a' and a third sub-section 20a'', which are in Fig. 3A are in fluid contact with each other via a narrow gap (not visible) between the stationary spiral 2 and the orbiting spiral 12.

[0100] On the right side of the Fig. Figure 3A shows a phasor diagram representing the orbital angle 103 of the orbiting disk 11 (and thus the orbiting spiral 12) and its orbital direction or compression direction 100. The orbiting disk 11 begins a new orbit when its orbital position 103 in the phasor diagram is at an orbital angle 101 of 0°. At this point, the orbiting spiral 12 touches the outer end 5 of the stationary spiral 2, thereby closing the compression chamber of the penultimate stage 20b. Simultaneously, an outer end 15 of the orbiting spiral 12 touches an outer surface of an outermost turn of the stationary spiral 12, thereby closing the compression chamber of the penultimate stage 20b'. Fig. 3A, the orbiting disk has already moved from the orbital angle 101 of 0° along the orbital direction 100 to the orbital position 103 of 45°.

[0101] In the compressor channel 6, a reference opening 50 is arranged in the stationary base area 3 at a position angle of 360° to the inner end 4 of the stationary spiral 2. It is located in Fig. 3A is just swept over by the sub-area 20a'' of the compression chamber of the last stage 20a, 20a', 20a'' and is in fluid communication with the entire compression chamber of the last stage 20a, 20a', 20a''.

[0102] Starting from Fig. 3A continues to orbit the orbiting disk along the direction of rotation 100 around a center of the stationary spiral 2.

[0103] In Fig. 3B means that the orbiting disk 11 has completed one quarter of its orbit. Its orbital position 103 is now at an orbital angle 102 of 90°.

[0104] The two compression chambers of the penultimate stage 20b, 20b' from Fig. 3A are propagated along the compression direction 100 in the compressor channel 6 further towards the center of the stationary coil 2. In doing so, they have each decreased in volume and the refrigerant enclosed within them has been compressed accordingly. The volume of the final stage compression chamber 20a, 20a', 20a'' has also decreased. The subsection 20a of the final stage compression chamber 20a, 20a', 20a'' consists of Fig. 3A has largely collapsed, and the outlet opening 7 in the stationary base 3 is just covered by an inner end 14 of the orbiting spiral 12. The reference opening 50 is in Fig. 3B is still covered by sub-area 20a'.

[0105] For a rotation angle between 90° and 180°, the sub-areas 20a' and 20a'' merge.

[0106] If the orbiting disk 11 starts from Fig. 3B orbits a further 270° along the compression direction 100 relative to the stationary disk 1, reaches a rotational position of 0° and its current rotation ends. The refrigerant that was in at the beginning of the rotation Fig. The fluid 3A, which was located in the compression chamber of the last stage 20a, 20a', 20a'', has been largely directed into the outlet opening 7. The combined sub-sections 20a' and 20a'' form the new sub-section 20a' for the following, new cycle. The compression chamber of the penultimate stage 20b from Fig. 3A and Fig. 3B becomes the new sub-area 20a', the compression chamber of the penultimate stage 20b' becomes the new sub-area 20a'' and the orbiting disk 11 begins the new revolution.

[0107] The refrigerant that is in Fig. 3A, which was found in the compression chambers of the last stage 20b, 20b', does not (yet) come into fluid contact with the outlet opening 7 until the beginning of the new cycle, but only during the course of this new cycle.

[0108] At the orbital angle 101 of 0° at the beginning of the new orbit, the new sub-sections 20a, 20a', 20a'' are not yet in fluid contact. As soon as the orbiting disk 11 continues orbiting, however, the new sub-sections 20a, 20a', 20a'' come into fluid contact with each other through narrow gaps and together form the new compression chamber of the last stage 20a, 20a', 20a'' for the new orbit. When the orbital position 103 of 45° is reached in the new orbit, the Fig. 3A shows the current state.

[0109] During the first part of a revolution of the orbiting disk 11, the reference opening 50 is swept over and closed by the orbiting spiral 12. Then, during the second part of the revolution, it is in fluid contact with the sub-section 20a'' and consequently with the entire compression chamber of the first stage 20a, 20a', 20'' (see Fig. 3A and Fig. 3B). Subsequently, during a third part of the orbital period, it is again swept over and sealed by the orbiting spiral 12. Then, during a fourth part of the orbital period, it is in fluid communication with the compression chamber of the penultimate stage 20b'. Finally, during a fifth part of the orbital period until the end of this orbit, it is again covered and sealed by the orbiting spiral 12.

[0110] Thus, an increasing high pressure is present at the reference port 50 during the second part. This is because the refrigerant in the final stage compression chamber 20a, 20a', 20a'' is already compressed to a certain degree when it comes into fluid contact with the reference port 50. At the beginning of the fourth part, when the penultimate stage compression chamber 20b' comes into fluid contact with the reference port 50, the reference pressure drops to a minimum value. It then rises continuously again during the fourth part. During the first, third, and fifth parts, the reference pressure at the reference port 50 remains approximately unchanged, as the reference port 50 is closed. The average reference pressure is calculated as the integral of the reference pressure over the cycle time divided by the cycle time.

[0111] If the reference aperture 50 differs from the illustration in Fig. 3A and Fig. 3B and, deviating from the invention, is arranged on an inside or on an outside of the compressor channel 6, the reference opening 50 is covered and closed by the orbiting spiral 12 only once during the rotation period. If, for example, it is at the same position angle as in Fig. 3A and Fig. 3B, however, being located on the inside in the compressor channel 6, is only covered once by the orbiting spiral 12 and does not come into fluid contact with the compression chamber of the penultimate stage 20b, but with the other compression chamber of the penultimate stage 20b'.

[0112] Based on Fig. 4A and Fig. Section 4B now explains at what position angle the reference opening 50 should be arranged. Fig. Figure 4A shows a top view of another embodiment of a stationary disk 1 of a spiral compressor according to the invention, for example for the one described in Fig. 2 and Fig. The embodiments shown in Figure 2A feature a stationary spiral 2 with two turns. The same reference numerals are retained for identical features, even if the stationary disk 1 consists of... Fig. 4A and Fig. 4B from stationary disk 1 Fig. 3A and Fig. 3B differs in detail.

[0113] A position angle 58 of 0° is defined by the inner end 4 of the stationary spiral 2. It should be noted that a termination bead 4A' of the inner end 4 is irrelevant for defining the position angle of 0°.

[0114] Since the stationary coil 2 in Fig. 4A, which has two turns, has its outer end 5 arranged at a position angle or spiral angle 9 of 720°. Accordingly, an inlet opening of a compressor channel 6, which extends between the outer end 5 and the beginning of an outer turn of the stationary spiral 2 at a position angle of 360°, is located at the spiral angle 720°.

[0115] Depending on the spiral angle 9, the reference opening 50 should be positioned within the hatched area 55. The area 55 extends within the compressor channel 6 between a minimum position angle 56 for the reference opening 50 and a maximum position angle 57 for the reference opening 50. Starting from any spiral angle greater than or equal to 450°, the minimum position angle 56 is calculated using the formula: 315° / (0.5 · spiral angle / 360°). 0,1 and the maximum position angle 57 from the formula 435° * (0.5 · spiral angle / 360°) 0,2In the present case, the minimum position angle 56 is therefore 315° and the maximum position angle 57 is consequently 435°. The reference aperture 50 is in Fig. 4A and Fig. 4B is provided for example at a position angle of 54 of 375° in the area 55.

[0116] In Fig. 4B, the minimum position angle 56, the position angle 54 of the reference aperture 50, the maximum position angle 57 and the spiral angle 9 are highlighted again.

[0117] If the contact pressure is greater than the reference pressure, oil and / or refrigerant flows from the contact pressure chamber 40 through the reference connection 51 and the reference opening 50 into the compressor unit. This reduces the contact pressure 40. In this process, the oil and / or refrigerant, which is already under the contact pressure, is reintroduced into the compression process and is not simply blown out to a lower pressure level outside the compressor unit. Thus, the compression work stored within it is used to increase the pressure in the compression chamber 20a, 20a', 20b, 20b', which is currently in fluid communication with the reference opening 50, and is not wasted.

[0118] The following Table 1 provides an example of an air conditioning system with a spiral compressor according to the invention. Fig. 2 and a refrigerant R134a, showing how the contact pressure p b (in MPa) depending on the intake pressure p sand the outlet pressure p d sets.

[0119] Table 1 shows that there is a pressure difference between the contact pressure p b and the intake pressure p s with increasing intake pressure p s increases, provided the outlet pressure p d does not decrease. Furthermore, this pressure difference tends to increase with increasing outlet pressure p. d on, provided p s does not sink.

[0120] A total force F with which the orbiting disk 11 is pressed against the stationary disk 1 results from the contact pressure p d The resulting contact force minus the opposing lifting force. Table 2 below shows an example of the total force F (in N) for the air conditioning system to which Table 1 refers.

[0121] The friction between the orbiting disk 11 and the stationary disk 1 during compression operation depends (at least approximately) linearly on the total force F. Table 2 shows that, with the present invention, the total force F at a given outlet pressure p d tends to increase with increasing intake pressure p s increases. In particular, this is the case at low intake pressure p. s Generally, only a small total force F is generated. Accordingly, the friction between the orbiting disk 11 and the stationary disk 1 is low at low intake pressure p. s The orbiting disk 11 is low and can be moved with particularly little effort. This also facilitates switching on, starting up, and spinning up the orbiting disk 11. At the same time, the invention ensures low friction at low suction pressure p. s and low outlet pressure p d .

[0122] The total force F remains significantly greater than 0 throughout the entire operating range. The lifting force, and thus the contact force required to overcome it, increases with increasing suction pressure p. s strongly when the outlet pressure p d does not decrease, and are increased with increasing outlet pressure p d greater when the intake pressure p s does not decrease. Therefore, in order to ensure a reliable seal of the compressor unit with constant percentage fluctuations in the lifting force and / or the contact force, the total force F at high outlet pressure p is determined by the present invention. d and / or at high intake pressure p s total greater than in the case where both the outlet pressure p d as well as the intake pressure p s are low.

[0123] In summary, the present invention provides a simple and cost-effective, yet effective, adjustment of the contact pressure depending on the operating condition of the scroll compressor. It ensures reliable, safe, and efficient operation of the scroll compressor under various operating conditions. Reference symbol list: 1 stationary disk 2 Stationary coil 3 Stationary floor area 4 inner end 4a End bead 5 outer end 6 compressor channel 7 Outlet opening 8 Check valve 9 spiral angles 11 Orbiting disk 12 orbiting spirals 15 outer end 20a Sub-area 20a' Sub-area 20a'' Sub-area 20b, 20b' Compression chamber of the penultimate stage 30 Exhaust pressure chamber 31 oil separators 32 Oil reservoir 33 Return connection 34 Throttle valve 40 Contact pressure chamber 50 Reference opening 51 Reference connection 52 damping chamber 54 Position angles 55 area 56 Minimum position angle 57 Maximum position angle 58 Position angles 60 Intake pressure chamber 61 Intake port 62 Outlet connection 63 Outlet connection 70 electric motor 71 Rotor 72 Stator 80 Inverter 100 Direction of rotation 101 Rotation angle 102 rotation angle 103 Circulation position

Claims

[1] Scroll compressor for compression of a fluid with a stationary disk (1) with a stationary spiral (2), wherein the stationary spiral (2) is arranged on a stationary base surface (3) of the stationary disk (1) and forms a spiral compressor channel (6) which extends from an outer end (5) of the stationary spiral (2) to an outlet opening (7) for the compressed fluid at an inner end (4) of the stationary spiral (2), wherein the stationary spiral (2) has a spiral angle (9) of more than 450°; an orbiting disc (11) with an orbiting spiral (12), wherein the orbiting spiral (12) is arranged on an orbiting base surface of the orbiting disc (11), wherein the orbiting disc (11) is orbitable relative to the stationary disc (1) along a compression direction (100), wherein furthermore the orbiting spiral (12) and the stationary spiral (2) are arranged nested in one another in such a way that at least two compression spaces (20a, 20a', 20a'', 20b, 20b') are delimited by the stationary base surface (3) and the stationary spiral (2) as well as by the orbiting base surface (12) and the orbiting spiral, wherein each of the compression spaces (20a, 20a', 20a'', 20b, 20b') shifts from an intake region of the compressor channel (6) towards an outlet region of the compressor channel (6) and thereby reduces its volume when the orbiting disc (11) orbits relative to the stationary disc (1) along the compression direction (100); an outlet pressure chamber (30) in fluid communication with the outlet opening (7); a contact pressure chamber (40) which is subjected to a contact pressure during compression operation, the orbiting disc (11) being pressed against the stationary disc (1) by the contact pressure; a return connection (33) which forms a fluid connection from the outlet pressure chamber (30) to the contact pressure chamber (40); a reference opening (50); and a reference connection (51) which forms a fluid connection between the contact pressure chamber (40) and the reference opening (50) for influencing the contact pressure on the basis of a reference pressure applied to the reference opening (50) during compression operation, characterized bythat the reference opening (50) is arranged in the stationary base area (3) within the compressor channel (6) in such a way that the reference opening (50) is swept over twice by the orbiting spiral (11) during compression operation during one revolution of the orbiting disk (11) and is in direct fluid communication with a compression chamber of the last stage (20a, 20a', 20a'') for a first part of the time required for the revolution and with a compression chamber of the penultimate stage (20b, 20b') for a further part of the time required for the revolution, and wherein the reference opening (50) in the compressor channel (6) is arranged at a position angle (54) from the inner end (4) of the stationary spiral (2) which is at least 315° / (0.5 · spiral angle / 360°) 0,1 and a maximum of 435° * (0.5 · spiral angle / 360°) 0,2 amounts. [2] Scroll compressor according to claim 1, characterized by that the position angle (54) is at least 345° / (0.5 · spiral angle / 360°)0,1 and maximum 405° * (0.5 spiral angle / 360°) 0,2 amounts. [3] Scroll compressor according to one of the preceding claims, characterized by that in compression operation, an average pressure difference between the contact pressure and an intake pressure increases with increasing intake pressure if the outlet pressure remains at least substantially constant. [4] Scroll compressor according to one of the preceding claims, characterized by that a damping element (52) is provided in the reference connection (51) between the reference opening (50) and the contact pressure chamber (40). [5] Scroll compressor according to one of the preceding claims for an air conditioning system for motor vehicles, characterized by that the reference opening (50) in the stationary base (3) has an opening area between 0.5 mm 2 and 8.05 mm 2 preferably between 1.13 mm 2 and 3.15 mm 2 . [6] Scroll compressor according to one of the preceding claims, characterized by an oil separator (31) in the outlet pressure chamber (30) and an oil reservoir (32), wherein the return connection (33) leads from the oil reservoir (32) to the contact pressure chamber (40). [7] Scroll compressor according to one of the preceding claims, characterized by a flow valve (34), preferably a throttle (34), provided in the return connection (33). [8] Scroll compressor according to one of claims 1 to 7, characterized by that no valve is provided in the reference connection (51). [9] Scroll compressor according to one of claims 1 to 7, characterized by that a pressure control valve is provided in the reference connection (51), which closes the fluid connection between the contact pressure chamber (40) and the reference opening (50) when the reference pressure is at least 0.2 bar greater than the contact pressure, preferably at least 0.8 bar.

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