EP4285028A1

EP4285028A1 - Scroll compressor with direct return of oil from an oil separator into a compression portion

Info

Publication number: EP4285028A1
Application number: EP22701957.7A
Authority: EP
Inventors: Manuel Wagner
Original assignee: Sanden International Europe GmbH
Current assignee: Sanden International Europe GmbH
Priority date: 2021-01-26
Filing date: 2022-01-25
Publication date: 2023-12-06
Also published as: JP2024503927A; DE102021101627A1; DE102021101627B4; CN117255896A; WO2022161941A1; KR20230132587A

Abstract

Scroll compressor (1), comprising: – a compression portion (10) having an inlet (11) for drawing a fluid into the compression portion (10), an outlet (12) for expelling the compressed fluid, a stationary plate (20) having a stationary spiral (21) and an orbiting plate (30) having an orbiting spiral (31), wherein the orbiting plate (30) can be made to orbit relative to the stationary plate (20), – an oil separator (45) for separating oil from the compressed fluid and a direct oil return line (50) for direct return of oil from the oil separator (45) to the compression portion (10), wherein the direct oil return line (50) has at least one discharge opening (59a, 59b). The direct oil return line (50) also comprises an outgassing chamber (54) arranged between the first flow valve (53) and the discharge opening (59a, 59b), and a fluid return line (70) for returning fluid from the outgassing chamber (54) into the compression portion (10).

Description

Scroll compressors with direct oil return from an oil separator to a compression section

The invention relates to a scroll compressor for compressing a fluid with a compression section, which has an inlet of the compression section for sucking the fluid into the compression section, an outlet of the compression section for discharging the compressed fluid from the compression section, a stationary disk with a stationary scroll, and an orbiting disk with an orbiting spiral.

Scroll compressors are used, for example, as compressors in air conditioning systems, in particular in air conditioning systems for motor vehicles. They are also used as heat pumps. Compared to other types of compressors, they are characterized by particularly smooth, low-vibration and quiet operation.

The compression section forms the core of the scroll compressor. As the orbiting disk orbits relative to the stationary disk, the fluid—in particular a gas or gas mixture—is compressed. For this purpose, the orbiting spiral and the stationary spiral are nested in one another in such a way that they form compression chambers for the fluid between them. In relation to the stationary volute, each compression space with the fluid enclosed therein moves from an outer region of the stationary volute to the center thereof. The space available for the fluid becomes increasingly smaller and the fluid is compressed.

In operation, a maximum pressure of the fluid is reached at the outlet of the compression section. The fluid enters the compression section at an intake pressure and is discharged from it at a significantly higher discharge pressure. The fluid, which is increasingly compressed between the orbiting disk and the stationary disk, pushes the orbiting disk and the stationary disk apart. A lifting force therefore acts on the orbiting disc. The strength of the lift-off force depends in particular on the suction pressure, the discharge pressure and the geometry of the compression section. Typically, a change in exhaust pressure has a more significant impact on clamp pressure than a change in intake pressure.

In order to achieve a high level of compression, the compression spaces formed by the interlocking of the stationary disk and the orbiting disk and shifted towards the center must be sealed sufficiently tightly. So that the orbiting disk is pressed firmly and sealingly onto the stationary disk and no fluid escapes from the compression section, the orbiting disk is subjected to a contact pressure on its rear side opposite the stationary disk. For this purpose, a contact pressure chamber is provided on the back of the orbiting disc. The contact pressure presses the orbiting disk with a contact force in the direction of the stationary disk.

The engagement of the orbiting scroll with the stationary disk and the engagement of the stationary scroll with the orbiting disk create friction during operation. Electrically driven scroll compressors typically work in a speed range of 500 to ¹²⁰⁰⁰ rpm. A high level of friction is noticeable in the form of reduced efficiency.

Oil is fed into the compression chamber to lubricate the orbiting disc. Furthermore, an oil supply line can be formed from the contact pressure chamber through the orbiting disk. Oil from the contact pressure chamber can flow through the oil supply line between the stationary sheave and the orbiting sheave. The fluid discharged from the scroll compressor should contain as little oil as possible. An excessive amount of oil in the vented fluid can affect the efficiency of downstream components to which the vented fluid proceeds. For example, the efficiency of a refrigerant circuit can deteriorate as more oil is added.

Typically, the scroll compressor is the only component in a refrigerant circuit that requires oil to lubricate mechanically stressed parts within the refrigerant circuit itself. As a rule, a refrigeration circuit can be operated in different operating states. The efficiency of the refrigeration circuit is largely dependent on its operating status. For example, an excessive amount of oil can wet surfaces within heat exchangers with oil. This reduces a heat transfer coefficient in the respective heat exchanger. Consequently, the efficiencies of the evaporator and condenser decrease. As a result, the refrigerant circuit must be operated overall with a higher pressure ratio in order to provide the required cooling capacity. An excessive amount of oil thus reduces the overall efficiency and increases the stress on the mechanical components within the scroll compressor due to the increased pressure ratio.

Therefore, after the compression section, the compressed fluid is passed through an oil separator. The oil separator at least partially separates the oil from the compressed fluid. The separated oil is fed back into the contact pressure chamber via a (second) oil return.

During operation of the scroll compressor, the oil in the contact pressure chamber is subject to the contact pressure. An orifice of the oil supply line is arranged in a central area of a compressor channel of the orbiting disk, which is formed by the orbiting scroll on the orbiting disk. Due to this positioning and a continuous mass flow of a mixture of oil and refrigerant, which comes from a high-pressure side, a contact pressure at a medium pressure level is established in the contact pressure chamber. The contact pressure presses the orbiting disk with a contact force in the direction of the stationary disk. The positioning in the middle area is largely responsible for the desired and sufficiently large contact pressure. The contact pressure is variable and dependent on the operating pressures. This ensures a seal between the stationary disk and the orbiting disk at all operating points and keeps friction as low as possible.

Due to this positioning of the orifice of the oil supply line, however, the radially outer areas between the stationary disk and the orbiting disk are not optimally supplied with oil. This results in increased friction, reduced efficiency and, under certain circumstances, a shorter service life for the scroll compressor.

The object of the present invention is to provide a scroll compressor that enables more efficient operation and has higher reliability.

The above object is achieved by a scroll compressor for compressing a fluid.

The scroll compressor for compressing a fluid includes: having a compression section

• an inlet of the compression section for sucking the fluid into the compression section,

• an outlet of the compression section for expelling the compressed fluid from the compression section, • a stationary disc with a stationary spiral, and

• an orbiting disk with an orbiting spiral, the orbiting disk being orbitable relative to the stationary disk along a compression direction in order to transport the fluid from the inlet of the compression section to the outlet of the compression section and thereby to compress it; and an oil separator for separating oil from the compressed fluid; wherein the scroll compressor has a direct oil return for directly returning oil from the oil separator to the compression section, the direct oil return having at least one orifice.

Direct oil return continuously returns oil from the oil separator to the compression section during operation. This reduces friction in the compression section. Thus, the direct oil return allows for more efficient operation of the scroll compressor. In addition, the wear in the compression section is reduced. This increases the reliability and lifespan of the scroll compressor.

In operation, the oil separator is (at least essentially) subjected to the outlet pressure. The invention makes use of a difference between the pressure in the oil separator and the pressure of the fluid at the orifice opening in order to directly and purposefully return the oil from the oil separator to the compression section. A key advantage is that the oil flow is driven by the direct oil return from a pressure ratio of discharge pressure to suction pressure. The amount of oil returned depends essentially on this pressure ratio. For example, this amount is at an intake pressure of 3 bar and an outlet pressure of 15 bar a speed of 600 ^rpm same as with an inlet pressure of 3 bar, an outlet pressure of 15 bar but a speed of ⁸⁵⁰⁰ rpm.

The amount of oil returned by direct oil return is (at least substantially) independent of scroll compressor speed and (at least substantially) independent of the exact discharge pressure. Even at low speeds, the direct oil return returns a sufficient amount of oil to the compression section. The direct oil return and is therefore suitable for lubricating the compression section in a wide variety of load conditions of the scroll compressor. In particular, it improves lubrication at low speeds.

Furthermore, the direct oil return works independently of the contact pressure. Even if the contact pressure falls, the direct oil return will continue to return oil to the compression section as long as the discharge pressure remains sufficiently high.

In addition, the oil is held better in the scroll compressor. The inlet area no longer has to be supplied with oil that flows out of a contact pressure chamber into the compression section or is routed through an external part of a refrigerant circuit to the inlet of the compression unit. The external part of the refrigerant circuit means those areas of the refrigerant circuit that are outside of the scroll compressor. The fluid behind the oil separator contains less oil. Less oil is routed through the external part of the refrigerant circuit. Typically, a higher proportion of oil in the fluid in an external part of the refrigerant circuit results in poorer thermodynamic properties of the refrigerant-oil mixture. The proposed direct oil return reduces an oil circulation rate (English Oil Circulation Ratio, abbreviated OCR) of the refrigerant circuit clear. The direct oil supply brings the oil precisely into an inlet area of the compression unit. This improves the efficiency of the refrigerant circuit.

Particularly at low speeds, there is an increased risk with conventional spiral compressors due to the low mass flow of the refrigerant through the external part of the refrigerant circuit that oil will unintentionally remain in the external part of the refrigerant circuit.

Conversely, the proportion of oil that is available for lubrication within the scroll compressor and in particular within the compression section during operation increases. The active, direct oil return reduces the total amount of oil required for the operation of the scroll compressor. This lowers costs and reduces the weight of the refrigerant circuit. As a result, for example, the efficiency of a vehicle incorporating the scroll compressor increases.

The outlet of the compression unit is arranged at least essentially in a center of the stationary disk. In particular, the outlet of the compression unit can be located exactly in the center of the stationary disk.

The stationary volute forms a volute compressor channel (stationary disk) that extends from an outer end of the stationary volute to an inner end of the stationary volute. The inner end of the stationary scroll is at a center of the stationary scroll. It is located at an outlet opening of the stationary disc. The outlet of the compression section includes this outlet port. In particular, this outlet opening can form the outlet of the compression section. The stationary scroll can be arranged on a stationary base of the stationary sheave. The stationary scroll may be formed of a wall extending away from the stationary base parallel to a central axis of the stationary disk from the stationary base. An end face of the stationary spiral facing away from the stationary base area along this central axis is preferably flat and parallel to the stationary base area.

The outlet port may comprise a hole in the stationary base. In particular, the outlet opening can be designed as a hole in the stationary base.

Similarly, the orbiting scroll forms a helical compressor channel of the orbiting disk, which extends from an outer end of the orbiting scroll to an inner end of the orbiting scroll. In this disclosure and in the claims, the term “compressor duct” without further supplementation always refers only to the compressor duct of the stationary disk, unless explicitly stated otherwise and unless something else is absolutely necessary from the context.

The orbiting spiral can be arranged on an orbiting base of the orbiting disc. The orbiting scroll may be formed of a wall extending away from the orbiting base parallel to a central axis of the orbiting disc from the orbiting base. An end face of the orbiting spiral facing away from the orbiting base area along this central axis (of the orbiting disc) is preferably flat and parallel to the orbiting base area. The orbiting base may be parallel to the stationary base.

The stationary spiral and the orbiting spiral can each have exactly one spiral arm. The scroll compressor includes an orbiting mechanism for orbiting the orbiting disk relative to the stationary disk. During orbiting, the orbiting disk is displaced eccentrically relative to the stationary disk along an at least essentially circular path. The central axis of the orbiting disk is preferably moved in a circle around the central axis of the stationary disk. The central axis of the stationary disc can be perpendicular to the stationary base. It can extend through a center of the stationary disc and/or a center of the stationary scroll. In particular, the center of the stationary spiral can form the center of the stationary disc and vice versa.

During operation (compressor operation), at least one compression space is formed between the orbiting scroll and the stationary scroll. The aspirated fluid is trapped in the compression space, compressed in the compression space, moved toward the outlet port of the stationary disk, and finally pushed into this outlet port.

An intake region of the compressor duct is composed of all regions of the compressor duct that are at least temporarily in direct fluid communication with the inlet of the compression section when the orbiting disk orbits relative to the stationary disk along the compression direction. An outlet area of the compressor channel is made up of all areas of the compressor channel that are at least temporarily in direct fluid communication with the outlet of the compression section when the orbiting disk orbits relative to the stationary disk along the compression direction. A middle region of the compressor duct is made up of all regions of the compressor duct that cannot be in direct fluid communication with either the inlet of the compression section or the outlet of the compression section. These definitions apply to both the compressor channel of the stationary disk and the compressor channel of the orbiting disk. For purposes of this application, an innermost convolution or first convolution of a particular coil means a portion of that coil extending from its inner end to the point where it has once wrapped around its center.

A position angle of 0° is assigned to the inner end of the stationary spiral. The position angle increases continuously along the extension of the stationary scroll up to the outer end of the stationary scroll. A helix angle of the stationary scroll is given by its outer end. The spiral angle thus corresponds to the largest position angle of the stationary spiral.

This is explained as an example for a stationary volute with two turns: The first turn of the stationary volute begins with the inner end of the stationary volute at a position angle of 0° and ends at a position angle of 360°. The second and outermost wrap begins at a position angle of 360° and ends at a helix angle of 720° with the outer end of the stationary scroll.

Position angles in the compressor channel are defined accordingly. An outer end of the volute compressor duct is defined by a compressor duct inlet opening formed between the outer end of the stationary volute and an inner beginning of the outermost turn of the stationary volute.

For the purpose of this application, an outer side of a region of a respective spiral is a side of this region of the spiral which faces away from the center of the spiral in the radial direction. Accordingly, an inner side of that portion of the scroll is a side of that portion of the scroll that faces the center of the scroll in the radial direction. The compression section can form compression spaces guided on the inside and compression spaces guided on the outside. An internally guided compression space is formed and guided along the outside of the stationary scroll. An externally guided compression space is formed and guided along the outside of the stationary scroll.

At this point it should be emphasized that the definition of the compressor channel is independent of the definition of the compression space. In particular, the compression space does not have to be located completely in the compressor channel of the stationary disk at all times. For example, the compression space may be formed by having the outer end of the orbiting scroll contact an outside of the outermost turn of the stationary scroll. This seal closes and seals off a compression chamber that is routed on the inside. At this point in time, the newly formed compression chamber, which is routed on the inside, can still be (partially) outside of the compressor channel of the stationary disk. On the other hand, a compression space guided on the outside is closed by an outside of the orbiting scroll coming into contact with the outer end of the stationary scroll. At this point in time, the newly formed compression chamber, which is routed on the outside, is already completely within the compression channel. It is guided on an outside of the compressor duct. In other words, the outside of the compressor channel is formed by the inside of the stationary scroll.

In operation, there is a suction pressure at the inlet of the compression section and a discharge pressure at the outlet of the compression section. The intake pressure during operation is preferably in the range from 1 bar to 7 bar. Alternatively or additionally, the outlet pressure during operation is in the range from 8 bar to 32 bar. Exact suction pressure and discharge pressure may differ depending on the fluid used and the exact operating condition. During operation, the suction pressure and the discharge pressure can be determined by a system which is connected to the scroll compressor and through which the fluid compressed in the scroll compressor flows. Such a system can be, for example, a heat exchanger of an air conditioning system.

A maximum discharge pressure of the scroll compressor results from the geometry of the compression section and the respective suction pressure. In addition, dead volume of the stationary disk's exhaust port (exhaust bore) can affect the maximum exhaust pressure. The higher the suction pressure, the higher the maximum discharge pressure. For a given intake pressure, the maximum outlet pressure results from the compression of the fluid that can be achieved in the compression section due to the geometry on the basis of the known fluid equations, for example the equation for ideal gases or the van der Waals equation. The (actual) outlet pressure is usually lower than the maximum outlet pressure.

The inlet of the compression section may include multiple sections. In particular, the inlet can have a first inlet partial area, through which the compression chambers guided radially on the inside are supplied with fluid, and a second inlet partial area, through which compression chambers guided radially on the outside are supplied with fluid. The partial areas can be spatially separated from one another, for example in a radially outer area of the compression section on two opposite sides.

The direct oil return serves for the immediate, direct return of oil from the oil separator directly into the compression section. The direct oil return extends from the oil separator directly to the compression section. During operation, oil is pushed into the direct oil return by the pressure from the oil separator. This oil flows through the direct oil return along a flow direction of the oil, and exits from the orifice of the direct oil return into the compression section. The oil thus returned serves to lubricate the compression section.

In a preferred embodiment of the invention, the orifice (of the direct oil return) is arranged in an inlet area of the compression section, which during operation is at least partially in direct fluid connection with the inlet of the compression section. This ensures particularly good lubrication in the radially outer areas of the orbiting scroll and the stationary scroll.

Depending on the precise positioning of the orifice opening, it is possible, for example, for the orbiting spiral to temporarily sweep over and cover the orifice opening during operation. At this point, the orifice is then not in direct fluid communication with the inlet. It is also possible that during a complete rotation of the orbiting disk, the orifice opening is in direct fluid connection with the inlet in a first period of time, is swept over by the orbiting spiral in a second period of time, is in communication with a compression chamber in a third period of time and in a fourth Period of time is again swept by the orbiting spiral.

In a particularly preferred embodiment, the compression chamber (or any of the plurality of compression chambers) does not sweep over the orifice at any time. Alternatively or additionally, the orbiting spiral particularly preferably sweeps over the orifice opening exactly once during a complete revolution of the orbiting spiral.

The orifice of the direct oil return is preferably arranged in the stationary disk. This reduces the complexity and simplifies the production of the direct oil return. In particular, the mouth opening can be arranged completely in the stationary base. Alternatively, the orifice opening can be arranged entirely or partially in the inside or the outside of the stationary spiral. Such variants are more difficult to manufacture. In return, the lubrication on the inside or the outside of the stationary spiral can be improved even further.

In a particularly preferred embodiment, the orifice of the direct oil return is arranged in the intake area of the compressor channel (the stationary scroll), which during operation is at least temporarily in direct fluid connection with the inlet of the compression section, and/or arranged outside of the compressor channel. When the orifice is located at the outer end of the compressor duct, a first portion of the orifice may be located within the compressor duct and a second portion of the orifice may be located outside of the compressor duct.

According to another aspect, the orifice of the direct oil return is preferably arranged at a position angle in a range of y - 30° and y + 30°, where y is a position angle of the outer end of the compression duct. In this case, the orifice opening can also be arranged at a radial distance RM,I from the center of the stationary disk, where RM,I lies in a range between (Ri(y) - BK) and Ri(y), where Ri(y) a radial is the inside of the stationary volute at the outer end of the compressor duct (that is, at the outer end of the stationary volute), and BK is a width of the compressor duct in the radial direction at the outer end of the compressor duct. In this case, the orifice is thus located near the outer end (upstream end) of the compression duct. The mouth opening is then rale swept over at least once by the face of the Orbitierspi during a revolution. As a result, the oil escaping from the orifice is distributed particularly well. In particular, RM.I can be in a range between (RI(Y) - BK/2) and RI(Y). An orifice designed in this way contributes particularly well to lubrication in the area of compression chambers that are guided on the outside.

Alternatively, the orifice of the direct oil return is preferably located outside the stationary scroll and at a position angle ranging from 0 - 30° to 0 + 30°; where 0 = y + 180°. In this case, the orifice opening can also be arranged at a radial distance RM,2 from the center of the stationary disk, where RM,2 lies in a range from RA(0 - 360°) to RA(0 - 360°) + BK, where RA(0 - 360°) is a radial distance of the outside of the stationary scroll at position angle 0 - 360°. In this embodiment, the orifice opening is thus arranged outside of the stationary volute and at a position opposite to the outer end of the compressor duct in relation to the center of the stationary volute. As a result, the oil escaping from the orifice is distributed particularly well. In particular, RM,2 can be in a range between RA(0 - 360°) and RA(0 - 360°) + BK/2. An orifice opening designed in this way contributes particularly well to lubrication in the area of the compression spaces guided on the inside.

Particularly preferably, a plurality of orifice openings are formed, with at least one of the plurality of orifice openings being formed in accordance with one of the embodiments according to the penultimate aspect and at least one of the plurality of orifices is formed according to one of the embodiments according to the last aspect described. The benefits apply accordingly.

In an advantageous embodiment of the invention, the direct oil return includes a first flow control valve. The first flow control valve is preferably arranged between a first oil inlet of the direct oil return and the orifice (seen along the flow direction of the oil in the direct oil return). In general, however, the first flow control valve can also be arranged directly on the first oil inlet or on the orifice. The first flow control valve can in particular be formed by the first oil inlet and/or the second orifice itself. The first flow control valve reduces the mass flow of the oil (possibly with fluid dissolved in it), which is returned through the direct oil return.

The first flow control valve is particularly preferably designed as a throttle valve.

In this application, a throttle valve is preferably to be understood as an element which generates a pressure difference between the valve inlet and outlet. It can particularly preferably be an uncontrolled throttle valve. It can be, for example, an orifice or nozzle. This allows a simple, inexpensive and reliable implementation.

The first flow control valve is set up to reduce the mass flow of the oil (along with any fluid that may be dissolved therein) from the oil separator. In this way, a pressure in the direct oil return downstream of the first flow control valve (for example an intermediate pressure described below and/or an orifice pressure described below) can be influenced in a simple manner. In a particularly preferred embodiment, the direct oil return comprises the first flow control valve and an outgassing chamber located between the first flow control valve and the orifice of the direct oil return (viewed along the intended flow direction of the oil in the direct oil return). In other words, the outgassing chamber is arranged downstream of the first flow control valve and upstream of the orifice.

During operation, the direct oil return continuously removes oil from the oil separator and stores excess oil in the degassing chamber. The degassing chamber is located in the scroll compressor. The efficiency of the separation process is maximized by the continuous drawing off of the oil from the oil separator, for example at or near a bottom of the oil separator, and the active intermediate storage of the oil. The amount of oil leaving the compressor and entering an external refrigerant circuit is reduced to a minimum.

As previously mentioned, there is an increased risk, particularly at low speeds, due to the low mass flow of the refrigerant, that oil which has been expelled from the scroll compressor into the external part of the refrigerant circuit will unintentionally remain in the external part of the refrigerant circuit. Even in such a case, the oil from the degassing chamber continues to supply oil to the scroll compressor until the system is again in equilibrium. If I then change an operating point to a high-load point, the oil previously trapped in the external part of the refrigerant circuit is carried back into the scroll compressor by the high mass flow of the refrigerant and is collected and temporarily stored in the scroll compressor again. As a result, the system adjusts itself: It takes up or releases oil as required. In operation, the oil separator is (at least essentially) subjected to the outlet pressure. As a result, there is a high solubility for the fluid in the liquid oil in the oil separator. The first flow control valve reduces the mass flow of the oil (along with any fluid dissolved therein) from the oil separator. This helps the intermediate pressure in the outgassing chamber settle to a lower value than the outlet pressure. This also reduces the solubility of the fluid in the oil. Downstream of the first flow control valve, the oil may be supersaturated with fluid. In the degassing chamber, the supersaturated portion of the fluid in the oil can separate (at least partially) from the oil in a controlled manner. This reduces the risk of uncontrolled, strong formation of bubbles of the fluid in the oil downstream of the degassing chamber. If the supersaturated part of the fluid is completely separated from the oil, there is at most just as much fluid in the oil as can be dissolved in the oil under the given conditions in equilibrium (saturation part of the fluid in the oil).

From the oil separator, a first fluid connection leads direct oil return to the outgassing chamber. The first flow control valve can be arranged in this first fluid connection. A second fluid connection leads from the outgassing chamber to the direct oil return to the orifice.

The scroll compressor is preferably set up such that (in operation) an intermediate pressure in the outgas chamber is in a range from 0.2 bar to 6 bar above the suction pressure (of the compression section or the scroll compressor), extremely preferably in a range of 0.3 bar up to 5 bar above the suction pressure. The exact intermediate pressure can be influenced, for example, by the first throttle valve and/or by a fluid feedback, which is described further below. This ensures that enough oil comes out of the orifice of the direct oil return. In addition, it is ensured that no fluid flows through the direct oil return counter to the flow direction of the oil in the direct oil return. Too high a pressure drop between the intermediate pressure and the suction pressure could result in too much oil flowing from the degassing chamber into the compression section.

Alternatively or additionally, the scroll compressor is preferably set up such that the intermediate pressure in the outgassing chamber is at least 106% of the intake pressure during operation.

In this case, absolute values of the intake pressure can be different for different operating states and the absolute values of the intermediate pressure can be different for different operating states. The relationship between the intermediate pressure and the intake pressure can also be different for different operating states. However, the ratio should be at least 1.06 for all (proper) operating states.

The outgassing chamber particularly preferably has a volume in the range from 30 cm ³ to 150 cm ³ , very preferably in the range from 50 cm ³ to 90 cm ³ . On average, the oil stays in the degassing chamber long enough for at least a significant portion of the supersaturated portion of the fluid to evaporate. On the other hand, the intermediate chamber is so compact that it requires little space and can be easily integrated.

In an extremely preferred development, the direct oil return comprises a second flow control valve, which is arranged after the outgassing chamber (seen along the flow direction of the oil in the direct oil return). In particular, the second flow control valve in the second fluid connection, i.e. flow downstream of the degassing chamber and upstream of the direct oil return orifice. In particular, the second flow control valve can be designed as a throttle valve. As already defined above, the throttle valve can be an orifice or a nozzle, for example. It is possible that the second flow valve is formed integrally with the orifice and/or an oil inlet of the second fluid connection at the outgassing chamber. The second flow control valve serves to limit a mass flow of the oil from the outgassing chamber. As a result, the discharge pressure of the oil at the discharge opening can be influenced in a simple and reliable manner.

If the direct oil return has a plurality of orifices, the direct oil return (relative to the direction of flow of the oil in the direct oil return) preferably branches downstream of the outgassing chamber. Thus, only one intake chamber is necessary for the multiple orifices. This simplifies the design and manufacture of the scroll compressor and reduces its costs. It is also possible that several second fluid connections lead directly from the outgassing chamber.

It is extremely advantageous if the direct oil return (or the second fluid connection) branches off downstream of the second flow control valve. So only a common second flow control valve is necessary for the multiple orifice of the same direct oil return. This further reduces construction and manufacturing costs. In addition, the same muzzle pressure is then present at the multiple muzzle openings (at least essentially).

Alternatively, different second flow control valves can be provided for different ones of the plurality of orifices. The muzzle pressure can thus be set differently for different muzzle openings. In a particularly preferred embodiment, the scroll compressor has a fluid recirculation of fluid from the outgassing chamber into the compression section. In this way, the fluid that was separated from the oil in the outlet chamber can be returned to the fluid circuit.

The orifice of the fluid return is particularly preferably arranged in the compressor channel of the stationary disk. The mouth opening can be formed, for example, as a hole in the stationary base. At least a portion of the fluid return can be formed in the stationary disk. This reduces complexity and manufacturing costs.

The orifice opening of the fluid return is very preferably arranged in the central area of the compressor channel (the stationary disk). This ensures that no fluid can flow out of the orifice of the fluid return upstream of the inlet of the compression section. At the same time, it is ensured that the orifice opening of the fluid return does not come into direct fluid connection with the outlet opening of the stationary spiral. This ensures high efficiency and effectiveness of the scroll compressor.

The fluid return can have a check valve. The check valve prevents fluid from flowing into the outgas chamber from a compression space spanning the orifice of the fluid return. Alternatively or additionally, the fluid return can have a flow control valve. This makes it easier to purposefully set the intermediate pressure in the outgassing chamber higher than an average value of the pressure of the fluid (in the compression channel) at the orifice of the fluid return.

In another embodiment, fluid can flow (at least substantially) freely between the outgassing chamber and the orifice of the second fluid connection. That is, the second fluid return has neither a check valve nor a flow control valve. Then the intermediate pressure in the suction chamber is particularly directly influenced by the mean value over time of the fluid at the orifice of the fluid return.

According to a further aspect, the orifice opening of the fluid return is very preferably arranged at a position in the compressor duct at which a time average of the pressure of the fluid in the compressor duct during operation is in a range from 104% to 170% of the intake pressure, in a development in a range of 105% to 150%.

If, in an idealized view, the mass flows of the returned oil and fluid are left out, the intermediate pressure in the degassing chamber is precisely the mean value over time of the pressure of the fluid at the orifice of the fluid return. In fact, due to the mass flows of the returned oil and fluid, the intermediate pressure during operation is above the time-average pressure of the fluid at the orifice of the fluid return. This pressure differential causes fluid to flow from the outgassing chamber through the fluid return into the compression section. The pressure differential is maintained by feeding new oil from the oil separator into the degassing chamber along with the fluid dissolved therein. However, the intermediate pressure is decisively influenced by the mean value over time of the pressure of the fluid at the orifice of the fluid return.

The relationship between the mean time value of the fluid at the fluid return orifice and the suction pressure essentially depends on the geometry of the compression section and the exact position of the fluid return orifice in the compressor channel. It also remains essentially constant for different operating states, given the position of the mouth opening. On the other hand, the ratio can be specifically controlled by shifting the position of the orifice. The described Embodiment therefore represents a particularly simple, reliable and suitable for a wide variety of operating conditions approach to the targeted influencing of the intermediate pressure.

The absolute values of the intake pressure can be different for different operating states and the absolute values of this mean value over time can be different for different operating states. The relationship between the intake pressure and this mean value over time of the pressure of the fluid at the orifice of the fluid return can also be different for different operating states. However, the ratio should be in the specified range for all (proper) operating states.

The setting of the ratio described ensures an advantageous intermediate pressure in the outgassing chamber, for example according to one of the advantageous embodiments described elsewhere. The intermediate pressure is high enough that enough oil flows from the degassing chamber to the (at least one) orifice of the direct oil return, exits there and enters the compression section. On the other hand, the intermediate pressure is low enough that not excessive oil flows out of the degassing chamber and that in the degassing chamber at least a substantial portion of the fluid dissolved in the oil fed into the degassing chamber separates from the oil.

The ratio of the time average of the pressure of the fluid (in the compressor channel) at the orifice to the intake pressure can be determined, for example, using a calculation and/or measurement of the pressure of the fluid in the compressor channel averaged over one revolution at the position of the orifice for a given intake pressure take place. The determination can also be made based on the measurement and/or calculation of a compression ratio of the fluid in the compressor channel at the outlet opening of the fluid return, averaged over one revolution. Time ranges (or ranges of orbital angles) in which the orifice of the fluid return is closed by the orbiting spiral can be disregarded for the calculation of the mean value over time of the pressure of the fluid at the orifice of the fluid return.

The absolute values of the intake pressure can be different for different operating conditions. Absolute values of this mean value over time of the pressure of the fluid at the orifice of the fluid return can be different for different operating states. The relationship between the intake pressure and this mean value over time can also be different for different operating states. However, the mean value over time for all (proper) operating states should be in the stated range of 104% to 170%, in the further development of 105% to 150%, of the intake pressure in the respective operating state.

The orifice opening of the fluid opening is very preferably arranged outside the outlet area of the compressor channel. This ensures that the outlet opening of the fluid return is never acted upon by the fluid at the outlet pressure. In a development, the orifice is arranged in the compressor channel in such a way that there is never a direct fluid connection with a compression chamber of the last stage. Otherwise, an undesirably high intermediate pressure could occur in the outgassing chamber.

In a further aspect, the orifice of the fluid return is most preferably located at a position angle θ in the compression duct, where θ is in a range from y - 300° to y and where y is the position angle of the outer end of the compression duct. Most preferably, the fluid return orifice is located at a position angle θ1 in the compressor duct, where θ1 is in a range from y-300° to y-180°. The orifice opening can be arranged in such a way that it is only swept over by compression spaces guided on the outside and is closed exactly once per revolution by the orbiting spiral. For example, in this case, the sum of a distance of the orifice from the outside of the compressor duct at this position angle and a width of the orifice in the radial direction may be smaller than a width of the spiral arm of the orbiting scroll in the radial direction at the corresponding position angle of the orbiting scroll.

Alternatively, the fluid return orifice is most preferably located at a position angle θ2 in the compression duct, where θ2 is in a range from y - 120° to y. The orifice opening can be arranged in such a way that it is only swept over by compression spaces guided on the inside and is closed exactly once per revolution by the orbiting spiral. For example, in this case, the sum of a distance of the orifice from the inside of the compressor duct at this position angle and a width of the orifice in the radial direction may be smaller than a width of the spiral arm of the orbiting scroll in the radial direction at the corresponding position angle of the orbiting scroll.

Particularly preferably, the orifice of the fluid return is positioned such that it is in direct fluid communication with the inlet of the compression section (the suction pressure) for a maximum of 130° of 360° of the orbital angle of the orbiting disk per revolution. Alternatively or additionally, the orifice opening of the fluid return per revolution is particularly preferably closed by the orbiting spiral for a maximum of 130° of 360° of the revolution angle of the orbiting disc. This results in the time-averaged pressure of the fluid at the fluid return orifice and the intermediate pressure sufficiently high enough for good pumping of oil from the degassing chamber into the compression section.

According to a further aspect, the scroll compressor is particularly preferably set up such that during operation the intermediate pressure is at least 0.1 bar above the mean value over time of the pressure of the fluid (in the compressor channel) at the orifice of the fluid return. Due to the pressure difference, fluid that has become free in the outgassing chamber flows back through the fluid return into the compression section.

Alternatively or additionally, the scroll compressor is most preferably set up so that the intermediate pressure during operation is less than 2 bar above the mean value over time of the pressure of the fluid (in the compressor channel) at the orifice of the fluid return. If the intermediate pressure is very high, less of the fluid dissolved in the oil will switch back to the gas phase in the degassing chamber. In addition, excessive intermediate pressure can result in excessive oil flow from the degassing chamber to the direct oil return orifice. It has already been explained above that the intermediate pressure and a difference between the intermediate pressure and the mean value over time of the pressure of the fluid at the orifice of the fluid return can be influenced simply and specifically by precisely positioning this orifice.

For example, the intermediate pressure during operation can be in a range from 0.2 bar to 1.5 bar above the mean value over time of the pressure of the fluid (in the compressor channel) at the position of the orifice of the fluid return.

An inlet of the fluid return in the outgassing chamber above the oil inlet of the second fluid connection of the direct oil return is highly preferred arranged. Thus, only separated fluid flows into the fluid return; accordingly, liquid oil flows into the second fluid connection of the direct oil return. "Above" in this context means that the inlet of the fluid return opens in front of (i.e. above) the oil inlet of the second fluid connection of the direct oil return into the degassing chamber as seen along a direction of a gravitational force when the scroll compressor is in a desired direction relative to a direction of a gravitational force In particular, the inlet of the fluid return can be arranged at an upper end of the degassing chamber and/or the inlet of the second fluid connection of the direct oil return can be arranged at a lower end of the degassing chamber.

The desired operating position can be defined, for example, in that the central axis of the stationary scroll is at least substantially perpendicular to the direction of the gravitational force.

In a preferred embodiment, the scroll compressor has a discharge pressure chamber, the oil separator being in direct fluid communication with the outlet of the compression section via the discharge pressure chamber. The discharge pressure chamber is in direct fluid communication with the compression section. The oil separator is in direct fluid communication with the outlet pressure chamber and thus in direct fluid communication via the outlet pressure chamber with the outlet of the compression section. The discharge pressure chamber serves as a cushioning chamber for the discharged fluid. It smoothes the outlet pressure.

In a particularly preferred development, the outgassing chamber is formed outside of the outlet pressure chamber in the radial direction and encloses the outlet pressure chamber. The outgassing chamber has an essentially hollow-cylindrical basic shape, with the outlet pressure chamber being arranged coaxially in the center of the outgassing chamber. This allows a very compact structure.

The scroll compressor preferably comprises a contact pressure chamber, which is subjected to a contact pressure during compression operation, with the orbiting disk being pressed against the stationary disk by the contact pressure during operation.

The contact pressure chamber is located outside of the direct oil return. The contact pressure chamber is not part of the direct oil return. The oil returned by the direct oil return is not routed through an interior space of the contact pressure chamber, which is subjected to the contact pressure during operation. In a functional sense, the direct oil return "bypasses" the interior of the contact pressure chamber.

The direct oil return is spatially separated from the contact pressure chamber. It is separate from the contact pressure chamber.

In particular, the outgassing chamber is optionally designed in addition to the contact pressure chamber, that is to say separately. For example, the contact pressure chamber, seen parallel to the central axis, can be arranged on a side of the orbiting disk that faces away from the orbiting disk. The outgassing chamber, on the other hand, can be arranged, viewed parallel to the central axis, on a side of the stationary disk that faces away from the orbiting disk.

The scroll compressor particularly preferably includes a second oil return for returning oil from the oil separator to the contact pressure chamber. With the second oil return, oil is supplied to the contact pressure chamber. The second oil return can be used to apply pressure to the contact pressure chamber. A rear side of the orbiting disk, which faces away from the stationary disk, can form part of a boundary of the contact pressure chamber. The second oil return preferably leads from the oil separator directly to the contact pressure chamber. This keeps complexity low and makes the scroll compressor simple and inexpensive to produce.

In an extremely advantageous embodiment of the invention, the second oil return has a flow control valve. The flow control valve influences the effect of the second oil return. In particular, it affects the amount of oil that flows through the second oil return into the contact pressure chamber. In this way, the flow control valve helps to coordinate and set the correct contact pressure in the contact pressure chamber.

The flow control valve of the second oil return is particularly preferably designed as a throttle valve. This makes it much easier to adjust the contact pressure with the second oil return (and if necessary the reference return connection, see below). This increases the efficiency of the scroll compressor compared to designs without a throttle valve in the second oil return.

The second oil return is at least partially separate from the direct oil return (first oil return). The second oil return and the direct oil return can have a common starting area. In this case, the direct oil return branches off from the second oil return, the branch being located in front of the contact pressure chamber as viewed along the second oil return (seen in the flow direction of the oil). The branching is particularly preferably located along the second oil return (in Flow direction of the oil seen) in front of the flow control valve of the second oil return. The initial common area begins with a common oil inlet that opens into the oil separator.

In a highly preferred embodiment of the invention, the direct oil return has a first oil inlet opening into the oil separator and the second oil return has a second oil inlet opening into the oil separator. The second oil inlet is different from the first oil inlet. The second oil inlet is formed separately from the first oil inlet. In particular, the second oil inlet can be formed at a spatial distance from the first oil inlet.

In a development, the second oil return has priority over the direct oil return in the event of a lack of oil. If a quantity of the liquid oil in the oil separator falls below a predetermined value, an oil flow through the direct oil return is reduced in relation to an oil flow through the second oil return and/or the oil flow through the direct oil return is stopped completely.

In this state, less or no oil is introduced into the compression section by the direct oil return. As a result, friction in the compression section increases and efficiency deteriorates. However, the contact pressure chamber continues to be supplied with oil. Temporary lack of lubrication can be temporarily compensated by the oil in the degassing chamber. The orbiting disk is thus further lubricated at least from its rear side. In addition, if necessary, parts of the orbiting mechanism that are located in the contact pressure chamber continue to be lubricated. In addition, the contact pressure in the contact pressure chamber can be maintained more easily. In this way, the scroll compressor at least remains functional. Some lubrication of the compression section can, for example by oil trickling from the applied pressure chamber past the orbiting disk into the compression section, by oil flowing from the applied pressure chamber into the compression section through a reference connection described below, and/or by oil entrained by the aspirated fluid .

In an extremely preferred embodiment, the first oil inlet is located above the second oil inlet. "Above" in this context means that when the scroll compressor is positioned in the desired operating position relative to the direction of the gravitational force, the first oil inlet opens before (i.e. above) the second oil inlet in the oil separator as seen along the direction of the gravitational force. In other words, the first oil inlet in the oil separator opens above the second oil inlet. In particular, the second oil inlet can be arranged at a lower end of an oil reservoir in the oil separator. If an oil level within the oil separator falls from a normal level, with such an arrangement initially only the first oil inlet will dry out.

Alternatively or additionally, the scroll compressor can have a valve mechanism by which an oil flow through the direct oil return is automatically reduced or stopped when the quantity of liquid oil in the oil separator falls below the predetermined value. The valve mechanism may include one or more valves. If the second oil return and the direct oil return have a common starting area, a diverter valve can be formed, for example, at the junction of the direct oil return from the second oil return. The valve mechanism can have a level sensor that detects when the amount of liquid oil in the oil separator falls below the predetermined value. Alternatively or additionally, the direct oil return is very preferably configured completely separately from the second oil return. This means that the direct oil return does not open directly into the second oil return at any point (or vice versa). In particular, in this case both do not have a common starting area. In this sense, the second oil return and the direct oil return are not directly fluidly connected. Of course, this does not preclude the first oil inlet of the direct oil return and the second oil inlet of the second oil return from being directly (but indirectly) in fluid communication with one another via the interior of the heat exchanger.

More preferably, the scroll compressor has a reference port located in the compression section and a reference connection that establishes fluid communication between the applied pressure chamber and the reference port. The reference connection can be designed to influence the contact pressure using a reference pressure present at the reference opening during operation.

The reference opening may be formed in the orbiting base in the compression channel of the orbiting disk or in the stationary base in the compression channel of the stationary disk.

Most preferably, the reference opening is formed in the orbiting base in the compression channel of the orbiting disc and the reference connection extends through the orbiting disc. The reference connection can thus be implemented very simply and inexpensively.

The contact pressure is directly influenced by the reference pressure. The reference pressure depends on the given position of the reference opening in the compressor channel in turn, depends heavily on the intake pressure and possibly also on the outlet pressure. In this respect, a difference between the contact pressure and the intake pressure adapts itself to an operating state of the scroll compressor. A complex, external, vulnerable and expensive control of the contact pressure is not required for this. In particular, no actively variably adjustable pressure control valve is required for setting and controlling the contact pressure. Through the interaction of the reference return connection and the reference opening, a pressure equilibrium is established in the contact pressure chamber. The automatic setting of different, respectively desired contact pressures for different operating states of the scroll compressor is achieved through the targeted design and coordination of the reference return connection and the reference opening, in particular the exact positioning of the reference opening in the corresponding compressor channel. Accordingly, the contact pressure with which the orbiting disk is pressed onto the stationary disk by the contact pressure is adjusted for different operating states to the lifting force acting on the orbiting disk in the respective operating state. This improves the efficiency and reliability of the scroll compressor.

The reference connection may include a flow control valve. In particular, the flow control valve can be designed as an uncontrolled throttle valve. This allows the contact pressure to be additionally influenced. The flow control valve can also help to ensure that the pressure differences during one revolution of the orbiting disk do not act undamped in the contact pressure chamber.

Oil from the contact pressure chamber between the stationary disk and the orbiting disk is very preferably routed through a reference connection. In this case, the scroll compressor has an “indirect oil return” in addition to the direct oil return, which returns oil from the oil separator indirectly and only indirectly via the interior of the contact pressure chamber into the compression section. The indirect oil return includes the second oil return and the reference connection. Such an indirect oil return is of course not a direct oil return within the meaning of this disclosure.

In an extremely preferred embodiment of the invention, the scroll compressor has two compression chambers, with the reference opening being arranged in the compressor channel (the stationary disk or the orbiting disk) in such a way that the reference opening is in compression mode during one revolution of the orbiting disk for a first part of the time required for the revolution is in direct fluid communication with a final stage compression chamber for a portion of the time and with a penultimate stage compression chamber for a further portion of the time required for the circulation. In this case, the first part and the further part together do not have to result in the entire time required for the circulation. Rather, there may be other parts.

This targeted positioning of the reference opening ensures that a high-pressure area of the scroll compressor also has an influence on the contact pressure and that the contact pressure in compression mode always remains high enough in every operating state, so that the contact pressure on the orbiting disc is sufficiently greater than the lifting force. As a result, the orbiting disk is pressed sealingly onto the stationary disk in compression mode in any operating state.

The compression chamber of the last stage is characterized in that the fluid contained in it is at least partially guided into the outlet opening during compression operation while the orbiting disk rotates. The compression chamber of the penultimate stage is characterized in that the fluid located in it is at least partially guided into the outlet opening during the compression operation within the next rotation of the orbiting disk. For further explanations, details and design options regarding the reference return connection and the reference opening, especially for a reference opening in the compressor channel of the stationary disk, reference is made to the published patent applications DE 10 2017 125 968 A1 and WO 2019/092024 A1. The disclosures contained therein apply - insofar as adequate - accordingly to a reference opening in the compressor channel of the orbiting disk.

The scroll compressor may include a suction pressure chamber in fluid communication with the inlet of the compression section. In particular, the suction pressure chamber can be in direct fluid communication with the inlet of the compression section. During operation, the suction pressure chamber is acted upon by the suction pressure.

The scroll compressor may include a suction port. The suction port may be in fluid communication with the inlet of the compression section via the suction pressure chamber.

The scroll compressor may have a discharge port. The outlet port may be in fluid communication with the oil separator. Preferably, an oil separator outlet port for the fluid in the oil separator, which is in direct fluid communication with the outlet port, is located above the first oil inlet of the direct oil return (and optionally the second oil inlet of the second oil return). "Above" in this context means that the oil separator outlet opening in the oil separator is located in front of (i.e. above) the first oil inlet when viewed along the direction of the gravitational force when the scroll compressor is positioned in the desired operating position relative to the direction of the gravitational force. In a development of the invention, the outlet of the compression section includes a non-return device. It can include, for example, a non-return flap and/or a non-return valve. The check unit prevents compressed fluid from flowing back (against the desired direction of flow) through the outlet of the compression section. Otherwise, fluid from the outlet pressure chamber could flow back through the outlet of the compression section when the outlet pressure in the outlet pressure chamber is higher than a pressure at the center of the stationary scroll.

The check device can (functionally and/or spatially considered) form a (downstream) end of the compression section.

Because the check is part of the outlet of the compression section, the oil separator is in fluid communication with the outlet of the compression section even when the check is closed. If the outlet pressure chamber is formed between the outlet of the compression section and the oil separator, the outlet pressure chamber within the meaning of this application is also in direct fluid communication with the outlet of the compression section when the non-return device is closed.

The outlet pressure chamber, the contact pressure chamber, the orbiting disk, the stationary disk, the return connection and the reference return connection are particularly preferably arranged in the suction pressure chamber. As a result, all of these components are securely enclosed by the suction pressure chamber. In this case, the suction connection and the outlet connection can be arranged on the suction pressure chamber, with the outlet connection being in fluid connection with the oil separator in a pressure-tight manner. In a development of the invention, the stationary spiral has at least 1.25 turns. This corresponds to a spiral angle of the stationary spiral of at least 450°. This ensures sufficient maximum compression of the scroll compressor for common applications.

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 scroll compressor compact, light and cheap to produce.

More preferably, the stationary scroll has two turns, with the reference opening (to the contact pressure chamber) in the compressor duct being arranged at a position angle from the inner end of the stationary scroll which is at least 315° and at most 435°, most preferably at least 345° and at most 405° . This arrangement has proven to be particularly practical.

If the second return connection has a plurality of orifice openings and/or a plurality of second return connections each having at least one orifice opening are provided, the individual orifice openings can be designed independently of one another according to any of the aforementioned embodiments and modifications. The benefits apply accordingly. It is therefore possible, for example, that all orifices are designed in the same way, that a first subset of all orifices is designed according to a first embodiment and a second part of all orifices is designed according to a second embodiment, or that all orifices are designed differently.

The scroll compressor preferably has an electric motor for driving the orbiting disk. The integration of the electric motor in the scroll compressor made possible a particularly precise and efficient operation of the scroll compressor. The operation of the electric motor can be fine-tuned to the specific scroll compressor. In particular, the drive of the scroll compressor is then not dependent on an operating state of other, external units. The electric motor is very preferably arranged inside the suction chamber. In a particularly preferred development, the scroll compressor is an electric scroll compressor with an integrated inverter.

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

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

The invention also 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.

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

The invention is explained below using exemplary embodiments and with reference to the figures. All of the features described and/or illustrated form the subject matter of the invention, either alone or in any combination, even independently of their summary in the claims or their back-references. They show schematically:

1 shows a longitudinal section of a first embodiment of a scroll compressor according to the invention;

FIG. 2 shows a compression section, an oil separator and a direct oil return for direct return of oil from the oil separator into the compression section of the scroll compressor from FIG. 1 ;

3 shows a cross section of the compression section from FIG orbiting disk of the compression section only one orbiting spiral is visible;

FIG. 4 is a plan view of a modification of the scroll compressor stationary disk of FIG. 3, showing in detail a preferred arrangement of the direct oil return orifices; FIG.

5 is a longitudinal sectional view of a compression section, a discharge pressure chamber, an oil separator, and a direct oil return for directly returning oil from the oil separator to the compression section according to a second embodiment of a scroll compressor according to the present invention;

Fig. 6 is a cross section taken along line A in Fig. 5; and FIG. 7 shows the top view of the stationary disk from FIG. 3 FIG. 7 for explaining advantageous positions for orifice openings for fluid return.

In Fig. 1 a first embodiment of a scroll compressor 1 according to the invention for compressing a fluid is shown schematically in a longitudinal section. The fluid is, for example, a refrigerant or a refrigerant mixture of a refrigerant circuit.

The scroll compressor 1 comprises a compression section 10 with an inlet 11, a stationary disk 20, an orbiting disk 30 and an outlet 12. An outlet pressure chamber 40 is directly connected to the outlet 12. In this embodiment, the outlet 12 comprises a non-return device 13 which prevents compressed refrigerant from flowing back from the outlet pressure chamber 40 into the compression section 10 . The non-return device 13 is shown here as a non-return valve and forms a downstream end of the compression section 10.

An oil separator 45 directly adjoins the outlet pressure chamber 40 as viewed along a flow direction of the refrigerant (in operation). The oil separator 45 is therefore in direct fluid connection with the outlet pressure chamber 40 and - via the outlet pressure chamber 40 - in direct fluid connection with the outlet 12 of the compression section 10.

The scroll compressor 1 comprises a housing 90 with a suction port 91 and a discharge port 92. The suction port 91 is in direct fluid communication with the inlet 11 of the compression section 10 via a suction pressure chamber 93. During operation, refrigerant is sucked in from an external refrigerant circuit via the suction port 91.

The outlet port 92 is in direct fluid communication with an oil separator outlet port 46 of the oil separator 45. During operation, compressed refrigerant is expelled through the outlet port 92 into the external refrigerant circuit.

During operation, suction pressure is present in the suction pressure chamber 93 and the inlet 11 of the compression section. The intake pressure can be in the range from 0.7 bar to 9 bar, for example. During operation, there is an outlet pressure in the outlet pressure chamber 40, the oil separator 45 and the outlet connection 92, which pressure is greater than the suction pressure. The outlet pressure can be in the range of 6 bar to 32 bar, for example. The intake pressure and the outlet pressure depend, among other things, on the refrigerant used and on an operating state of the external refrigerant circuit.

The suction pressure chamber 93 is only shown schematically in FIG. The intake pressure chamber 93 preferably encloses at least the contact pressure chamber 80 like a jacket. That is, the suction pressure chamber 93 extends along a circumferential direction (relative to the central axis) completely around the contact pressure chamber 80 . Alternatively or additionally, the intake pressure chamber 93 can enclose at least part of the compression section 10 in the manner of a jacket. That is, the suction pressure chamber 93 extends along the circumferential direction (with respect to the central axis) completely around the aforesaid part of the compression portion 10 . Said part of the compression section 10 can face the contact pressure chamber 80, in particular when viewed along the central axis. The intake pressure chamber 93 can be configured, for example, at least essentially in the shape of a cylinder jacket around the contact pressure chamber 80 and/or at least part of the compression section 10 on the side of the contact pressure chamber 80 .

The stationary disk 20 faces the outlet pressure chamber 40 while the orbiting disk 30 faces a contact pressure chamber 80 .

A cut surface for Fig. 3 is between the orbiting disk 30 and the stationary disk 20 in Figs. 1 and 2, respectively, and extends parallel to a stationary base 22 of the stationary disk 20. On the stationary base 22, a stationary scroll 21 with 2.25 turns is arranged . Correspondingly, an outer end 25 of the stationary scroll 21 is arranged at a helix angle of 810° from an inner end 24 of the stationary scroll 21 .

FIG. 4 is a simplified representation of a plan view of the stationary disk 20. For the sake of simplicity, the orbiting scroll 31 is shown in FIG. 4 as having a two-turn modification. Correspondingly, the outer end 25 of the stationary scroll 21 is arranged at a helix angle of 720° from the inner end 24 of the stationary scroll 21 . Otherwise, the structure and the function of the stationary disk 20 in FIG. 3 and FIG. 4 are the same and the same reference numbers are used for the same elements.

Back to FIG. 3, only one orbiting spiral 31 can be seen from the orbiting disk 30 due to the cross section, which is arranged on an orbiting base 32 (not shown in FIG. 3, but see FIG. 5) of the orbiting disk 30. The orbiting spiral 31 has (like the embodiment of the stationary spiral 21 in FIG. 3) 2.25 turns. The stationary disk 20 and the orbiting disk 30 are nested within one another. In (compression) operation, the orbiting disk 30 is pressed onto the stationary disk 20 by a contact pressure in the contact pressure chamber 80 (see FIG. 1 ). As a result, on the one hand, an end face of the orbiting spiral 31 facing away from the orbiting base 32 bears sealingly against the stationary base 22 and, on the other hand, an end face of the stationary spiral 21 facing away from the stationary base 22 bears sealingly on the orbiting base 32 .

The stationary base 22, the stationary spiral 21, the orbiting base 32 and the orbiting spiral 31 thereby delimit a plurality of compression chambers 14a, 14b, 14c.

In the position of the orbiting disk 30 or the orbiting scroll 31 shown in FIG 14c of the last stage comprises two subsections which are in fluid communication with one another via narrow gaps (not visible in FIG. 3) between the stationary scroll 21 and the orbiting scroll 31 .

A vector diagram is shown on the left-hand side of FIG. 3 that represents an orbital angle 103 of the orbiting disk 30 (and thus of the orbiting spiral 31 ) and its direction of orbit or a direction of compression 100 . The orbiting disc 30 begins a new revolution when its revolution position 103 in the pointer diagram is just at a revolution angle 101 of 0°. An outside of the orbiting scroll 31 then just touches the outer end 25 of the stationary scroll 21 and thereby closes off the compression chamber of the penultimate stage 14b that is guided on the outside. At the same time, an outer end 34 of the orbiting scroll 31 touches an outside of an outermost turn of the stationary scroll 21 and closes while the internally guided compression space penultimate stage 14a from. In FIG. 3, the orbiting disk 30 has already moved further along the compression direction 100, starting from the rotation angle 101 of 0°, to the rotation position 103 of 45°. Starting from Fig. 3, the orbiting disk 30 continues to orbit along the compression direction 100 around a center of the stationary scroll 21.

When the orbiting disk 30 orbits a further 270°, starting from FIG. 3 , along the compression direction 100 relative to the stationary disk 20 , it reaches an orbital position of 0° and its current orbit ends. The refrigerant that was in the compression space of the last stage 14c in FIG. The outlet opening 28 is arranged in a center of the stationary disk 20 or the stationary scroll 21 .

The scroll compressor 1 has a direct oil return 50 for returning oil from the oil separator 45 to the compression section 10 .

More specifically, the direct oil return 50 extends from a first oil inlet 51 in the oil separator 54 to two orifices 59a, 59b in the stationary base 22 of the stationary sheave 20. In operation, the direct oil return 50 injects oil from the oil separator 45 from the orifices 59a, 59b directly between the stationary disk 20 and the orbiting disk 30.

In the embodiment shown in Fig. 1, the direct oil return 50 includes, seen along the flow direction of the oil, the first oil inlet 51, a first fluid connection 52 with a first throttle valve 53, an exhaust chamber 54, a second fluid connection 56 with a second throttle valve 57 and a junction 58 and also two orifices 59a, 59b. During operation, the outlet pressure prevails in the interior of the oil separator 45 . In the oil separator 45 , the refrigerant rises while liquid oil collects in a lower half of the oil separator 45 . In this way, the refrigerant and the oil are separated from each other. Due to the high outlet pressure, there is an increased solubility for the refrigerant in the liquid oil and the liquid oil contains a proportion of dissolved refrigerant.

The first oil inlet 51 is arranged in a lower half of an inner space of the oil separator 45 , while the oil separator outlet port is arranged at an upper end of the inner space of the oil separator 45 . The outlet pressure forces liquid oil out of the oil separator 45 through the first oil inlet 51 into the first fluid connection 52 .

In the first fluid connection 52 of the direct oil return 50, this oil flows through the first throttle valve 53. The first throttle valve 53 can be designed as an uncontrolled throttle valve. For example, the first throttle valve 53 can be configured as an orifice or nozzle. The first throttle valve 53 reduces the mass flow of the oil. The oil then flows further into the outgassing chamber 54. By influencing the mass flow of the oil, an intermediate pressure in the outgassing chamber 54 can be influenced. Due to the pressure drop, the solubility for the refrigerant in the oil decreases. After the first throttle valve 53, the oil can be supersaturated with refrigerant. A supersaturated portion of the refrigerant can evaporate in the outgassing chamber 54 . Liquid oil collects in a lower portion of the outgassing chamber 54 and refrigerant collects in an upper portion of the outgassing chamber 54 . The outgassing chamber 54 acts, so to speak, as an additional oil separator of the direct oil return 50 and a fluid return 70. An oil inlet 55 of the second fluid connection 56 of the direct oil return 50 is arranged in the lower area of the outgassing chamber 54 , for example in a bottom area of the outgassing chamber 54 . The intermediate pressure prevailing in the outgassing chamber 54 forces liquid oil out of the outgassing chamber 54 through the oil inlet 55 into the second fluid connection 56 .

The second fluid connection 56 has a second throttle valve 57 which limits a mass flow of the oil emerging from the outgassing chamber. Incidentally, this also makes it possible to prevent an undesirably large drop in the intermediate pressure in the outgassing chamber 54 . The second throttle valve 57 can also be designed as an unregulated throttle valve, for example as an orifice or nozzle.

Downstream of the second throttle valve 57 , the second fluid connection 56 branches into two arms at a junction 58 . Both arms lead at least partially through the stationary disk 20. They each end in one of the orifice openings 59a, 59b, which are arranged in the stationary base 22.

Each of the orifice openings 59a, 59b is arranged in an inlet region of the compression section 10 which, during operation, is at least partially in direct fluid connection with the inlet 11 of the compression section 10. As a result, oil escaping from the orifices 59a, 59b is entrained by the refrigerant sucked in and then enclosed together with the refrigerant in newly formed compression chambers. Because the orifice openings 59a, 59b are each positioned in the inlet area of the compression section 10, the radially outer engagement areas of the stationary scroll 21 and the orbiting scroll 31 are also excellently lubricated. In addition, all orifice openings 59a, 59b are each swept over at least once by the orbiting spiral 31 during each revolution of the orbiting disk 30 . This ensures good distribution of the supplied oil. The oil emerging from the orifices 59a, 59b is smeared by the orbiting spiral 31. It can be seen from FIG. 4, for example, that the orifice opening 59a is swept over by an outer end 34 of the orbiting spiral 31 in each revolution.

Particularly preferred positions of the orifice openings 59a, 59b are discussed in more detail below with reference to FIG.

In the compression spaces 14a, 14b, 14c (see Fig. 3) formed in the compression section 10 between the stationary disk 20 and the orbiting disk 30, the refrigerant is transported to the center of the stationary scroll 21, thereby reducing the volumes of the compression spaces 14a, 14b, 14c is compressed until it has reached the outlet pressure. It is then conveyed through the outlet 12, which in this example comprises an outlet opening 28 in the center of the stationary disk 20 and the non-return device 13, and the outlet pressure chamber 40 into the oil separator 45.

Oil is also transported together with the refrigerant and finally gets back into the oil separator 45. There it is separated from the refrigerant and is available for a new cycle of direct oil return 50. The refrigerant freed from the oil, compressed and under the discharge pressure is discharged out of the scroll compressor 1 through the oil separator discharge port 46 and the discharge port 92 .

It will now be explained with reference to FIG. 4 where the orifice openings 59a, 59b of the direct oil return can preferably be arranged. A position angle of 0° is defined by the inner end 24 of the stationary scroll 21 . It should be noted that a terminal bead 24a of the inner end 24 is irrelevant in determining the position angle of 0°. Since the stationary scroll 21 in FIG. 4 has two turns, its outer end 25 is arranged at a position angle or a helix angle of 720°. Correspondingly, an inlet opening of a compressor duct 26, which extends between the outer end 25 and a start of an outer turn of the stationary scroll 21 at a position angle of 360°, lies at the position angle 720°.

Fig. 4 shows a preferred first area AM,I for the arrangement of orifices of the direct oil return 50.

In FIG. 4 , y is a position angle of the outer end 25 of the stationary scroll 21 . Accordingly, y is also a position angle of an outer end of the compressor channel 26. At the position angle y, the inside of the stationary scroll 21 has a distance Ri(y) in a radial direction from the center of the stationary scroll 21. At the same time, there is an inlet opening of the compressor channel 26 of the stationary disk 20 at the position angle in the radial direction, a width BK. Here, the width BK is given as BK=Ri(y)-RA(Y-360°), where RA(Y-360°) is a distance from the outside of the stationary scroll 21 at a position angle corresponding to Y-360°.

The first area AM,I extends in the circumferential direction from a position angle Y - 30° to a position angle of y + 30° and in the radial direction from Ri(y) - BK/2 to RI(Y)- This means that the first area AM,I is arranged at the inlet opening of the compressor duct 26, specifically on a radially outer half of the compressor duct 26 in this position angle range or its imaginary continuation. In Fig. 4, the orifice opening 59a is positioned in the first region AM.I, precisely at the position angle y=720° and close to the outside of the compressor channel 26, ie at a radial distance RI(Y) - BK/10 from the center, for example of the stationary spiral 21 . The mouth opening 59a is closed by the orbiting spiral 31 only once per revolution. In the embodiment shown, it does not come into direct contact with compression chambers 14b guided on the inside. The orifice 59a ensures, in a particularly advantageous manner, the lubrication of the compression chambers on the outside. In FIG. 3, the compression chamber 14a is guided on the outside.

Fig. 4 also shows a preferred second area AM,2 for the arrangement of orifices of the direct oil return 50. In this example, the orifice 59b is positioned in the second area AM,2.

The second area AM, 2 extends radially outside of the stationary scroll 21 around a position angle θ, where Q=y+180°. The second area AM, 2 extends in the circumferential direction from a position angle Q−30° to a position angle of Q+30° and in the radial direction from RA(9-360°) to RA(9-360°) + BK/2 . A second area AM, 2 therefore lies outside of the compressor channel 26 of the stationary disk 20 , more precisely on a side opposite the inlet opening of the compressor channel 26 . Here, RA(9 - 360°) is a radial distance of the outside of the stationary scroll 21 at the position angle Q - 360° = y - 180°.

In Fig. 4, the orifice opening 59b is positioned in the second region AM,2, precisely at the position angle Q=900° and close to the outside of the outermost turn of the stationary scroll 21, ie at a radial distance RA(9)+BK/, for example. 10 from the center of the stationary spiral 21 . the estuary In a particularly advantageous manner, opening 59b ensures the lubrication of compression chambers guided on the inside. In FIG. 3, the compression chamber 14b is guided on the inside.

In FIG. 3, the orifices 59a, 59b of the direct oil return 50 are also positioned as described with reference to FIG.

The scroll compressor 1 also includes a fluid return 70 for returning refrigerant from the outgassing chamber 54 into the compression unit. A fluid inlet 71 of the fluid return 70 is arranged in an upper area of the outgassing chamber 54 . In this way, no liquid oil flows from the outgassing chamber 54 into the fluid return line 70.

The fluid return 70 extends through the stationary disk 20. An orifice 72a of the fluid return 70 is disposed in the compressor passage 26 of the stationary disk 20 (see Figs. 3 and 5). Here, the orifice opening 72a is arranged in an inlet area of the compressor channel 26, but is sometimes also swept over by closed compression chambers. In FIG. 3, the compression chamber 14b of the penultimate stage just sweeps over the orifice 72a. Consequently, a time average of the pressure of the refrigerant in the compression passage 26 at the orifice 72a is higher than the suction pressure. In the present embodiment, the intermediate pressure in the outgassing chamber 54 during normal operation is above the mean value over time of the pressure of the refrigerant in the compressor channel 26 at the position of the orifice opening 72a, specifically - depending on the exact operating state - in the range from 0.2 bar to 1 .5 bars. The pressure difference to the outlet pressure forces liquid oil out of the outgassing chamber into the second fluid connection 56 and out of the orifices 59a, 59b of the direct oil return 50. The intermediate pressure in the outgassing chamber 54 is particularly influenced by:

- The outlet pressure and the mass flow of the oil, including the entrained refrigerant, which flow through the first fluid connection 52 into the outgassing chamber 54,

- the time averages of the pressures at the orifices 59a and 59b and the corresponding mass flow of oil leaving the outgassing chamber 54 through the second fluid connection 56, and

- The time average of the pressure of the refrigerant in the compressor channel 26 at the orifice 72a and the corresponding mass flow of the refrigerant that leaves the outgassing chamber 54 through the fluid return 70.

The driving force is the outlet pressure in the oil separator 45.

In this embodiment, the intermediate pressure (or a time average of the intermediate pressure in an unchanged operating state) is in the range from 0.3 bar to 5 bar above the intake pressure during operation. At an intake pressure of 1 bar, the intermediate pressure during operation is a minimum of 0.3 bar above the intake pressure, ie 1.3 bar in absolute terms, and a maximum of 1.9 bar, ie 1.9 bar in absolute terms. With an intake pressure of 7 bar, the intermediate pressure during operation is a maximum of 4.2 bar above the intake pressure, i.e. 11.2 bar. Of course, the intermediate pressure then remains well below the outlet pressure, which in this case is 32 bar. At an intake pressure of 5 bar, the intermediate pressure is in the range from 0.6 bar to 3.5 bar above the intake pressure. These values are examples. The exact intermediate pressure depends on the exact operating condition, for example also on the outlet pressure. The exact pressure ratios can also depend on the refrigerant used. In other words, the intermediate pressure during operation is in a range of 1.3 bar (minimum intermediate pressure) and 11.2 bar (maximum intermediate pressure).

Advantageous positions for orifice openings 72a, 72b of the fluid return 70 are explained below with reference to FIG.

In general, the orifice 72a, 72b of the fluid return 70 in the compressor duct 26 is preferably located at a position angle (of the compressor duct 26) that is in a range of Emin ~ y ~ 300 and Smax ⁼ y, where Y is the position angle of the outer end of the Compressor channel is.

Fig. 7 shows two particularly preferred areas AM, 3 and AM, 4 for the arrangement of orifices 72a, 72b of the fluid return 70 in the compressor channel 26.

The one area AM, 3 for the arrangement of orifices 72a is defined in that an orifice 72a of the fluid return 70 located therein is arranged at a position angle Ei, which is in a range from Emin = Y - 300° to _s max,i = Y-180°, the orifice opening 72a also being arranged in such a way that it is only swept over by the compression chambers 14b guided on the outside and is swept over by the orbiting spiral 31 exactly once per revolution. For example, the orifice opening 72a of the fluid return 70 in FIGS. 3, 4 and 7 is arranged in the compressor channel 26 at a position angle εi = Y - 248°. The orifice 72a is also located on the outside of the compression duct 26 at this position angle. As a result, in this embodiment, the orifice opening 72a is only swept over by compression chambers 14b guided on the outside. The mouth opening 72a is at no time in direct fluid communication with one of the compression chambers 14a guided on the inside. More specifically, in this embodiment, the orifice 72a of the fluid return 70 is closed by the orbiting scroll 31 in the orbit angle range of 0° to 20°. When the rotation angle has reached 20°, the compression chamber 14b guided on the outside begins to sweep over the orifice opening 72a. In a range of the angle of rotation from 20° to 270°, the orifice opening 72a and the compression space 14a guided on the outside are in fluid connection. With the rotation angle of 90° shown in FIG. 3, the orifice opening 72a of the fluid return 70 is in direct fluid connection with the compression chamber 14b guided on the outside, for example over its entire surface. In a range of the rotation angle from 270° to 360°, the orbiting spiral 31 closes the orifice opening 72a again.

At the circulation angle of 20°, the pressure of the refrigerant in the compression chamber 14b guided on the outside, which is just entering into fluid connection with the orifice 72a, is already slightly above the suction pressure. This is due to the fact that this compression space 14b was closed shortly before at the rotation angle of 0° (reference number 101) and was already slightly reduced up to the rotation angle of 20°.

An intake pressure of 3 bar is assumed for the following example. The pressure of the refrigerant in this compression chamber 14b is then, for example, 3.08 bar at the rotation angle of 20°. Up to the rotation angle of 270°, the pressure of the refrigerant in this compression chamber 14b increases continuously in this example to 4.76 bar. The mean value over time of the pressure of the refrigerant in the compressor channel 26 at the outlet opening 72a is 3.76 bar, which means it is 0.76 bar above the suction pressure of 3 bar. This is a non-limiting example of a specific operating state. Thus, in the embodiment according to FIG. 3, the mean value over time of the pressure of the refrigerant in the compressor channel 26 is at the position of the orifice opening 72a of the fluid return 70, for example

• at an intake pressure of 1 bar at 126% of this intake pressure,

• at an intake pressure of 3 bar at 125% of this intake pressure,

• at an intake pressure of 5 bar at 124% of this intake pressure and

• at an intake pressure of 7 bar at 123% of this intake pressure.

If the orifice 72a of the fluid return 70 is shifted to a position angle of Ei = Y - 295° in a modification of the embodiment not shown in the area AM, 3, then the time average of the pressure of the refrigerant in the compressor passage 26 is at the position of the orifice 72a of the fluid return 70 depending on the operating state, for example in the range from 138% to 142% of the respective intake pressure.

If the orifice 72a of the fluid return 70 is shifted to a position angle of Ei = Y - 190° in a modification of the embodiment not shown in the area AM, 3, then the time average of the pressure of the refrigerant in the compressor passage 26 is at the position of the orifice 72a of the fluid return 70 depending on the operating state, for example in the range from 107% to 109% of the respective intake pressure.

The other area AM, 4 for the arrangement of orifices 72b' is defined in that an orifice 72b of the fluid return 70 lying therein is arranged at a position angle θ2, which is in a range from Emin, 2 = Y - 120° to θ _m ax=Y, with the orifice opening 72b also being arranged in such a way that it is only swept over by compression chambers 14a guided on the inside and is swept over by the orbiting spiral 31 exactly once per revolution. 7 shows the position for an orifice opening 72b in the area AM, 4 with a position angle θ2=7-68°. The orifice 72b is also located on the inside of the compression duct 26 at this position angle θ2. As a result, this orifice opening 72b is only swept over by compression chambers 14a guided on the inside. The mouth opening 72b is therefore at no time in direct fluid communication with one of the compression chambers 14b guided on the outside. This orifice 72b can be formed as an alternative or in addition to the other orifice 72a of the fluid return 70 shown in FIG.

At the closure of the compression chambers 14a, 14b, the position angle of the inboard compression chambers 14b is offset from the position angle of the outboard compression chambers 14a by +180°. Since the position angle of the orifice opening 72b is also offset by +180° with respect to that of the orifice opening 72a, the pressure conditions at the orifice opening 72b develop similarly to those at the orifice opening 72a during a revolution.

In an embodiment that is not shown, an orifice of the fluid return 70 can be arranged, for example, at a position angle in the range of θmax,i to θmin,2. Such an orifice opening can be arranged in a central region of the compressor channel 26 at this position angle, so that it is completely closed twice in each revolution by the orbiting scroll 31 and alternately enters fluid communication with compression chambers 14a guided on the inside and with compression chambers 14b guided on the outside. As a result, the average pressure of the refrigerant at this orifice lies between the average pressure of the refrigerant in the compression chambers 14b guided on the outside on the outside of the compressor channel 26 at this position angle and the average pressure of the refrigerant on the inside. tig guided compression chambers 14a on the inside of the compressor channel 26 this position angle. As already mentioned elsewhere, the time ranges during which the orifice opening is completely closed by the orbiting spiral 31 can be left out for the calculation of the mean pressure of the refrigerant at the orifice opening.

The scroll compressor 1 also has a second oil return 82 . The second oil return 82 returns oil from the oil separator 45 to the contact pressure chamber 80 . It includes a second oil inlet 81 in the oil separator 45 and a throttle valve 83 which is arranged between the second oil inlet and the contact pressure chamber 80 in the second oil return 82 .

During operation, the outlet pressure prevailing in the oil separator 45 forces oil through the second oil inlet 81 into the second oil return 82 . The pressure of the oil is reduced by the throttle valve 83. The pressure drop in the throttle valve 83 influences the contact pressure.

The oil in the contact pressure chamber 80 contributes to lubricating the orbiting disk 30 . In addition, a small portion of the oil can creep past the orbiting disk 30 into the interior of the compression section 10 .

The scroll compressor 1 shown in Fig. 1 also includes a reference connection 84 between an interior of the contact pressure chamber 80 to a reference opening 86. The reference opening 86 is arranged in the orbiting base 32 of the orbiting disk 30, namely in a compressor channel of the orbiting disk 30. The reference connection 84 influences the contact pressure in the contact pressure chamber 80 as a function of the operating state of the scroll compressor 1. The reference connection 84 leads from the contact pressure chamber 80 through the orbiting disk 30 to the reference opening 86 in the orbiting base 32. The reference opening 86 of the reference connection 84 is positioned further inwards than the orifice openings 59a, 59b of the direct oil return 50, viewed in the radial direction . Therefore, the reference connection 84 can contribute little or not to the lubrication of the radially outer areas of the stationary scroll 21 and the orbiting scroll 31 . The reference opening 86 is not arranged in the inlet area of the compressor channel of the orbiting disk 30 . During operation of the scroll compressor 1, there is therefore no direct fluid connection between the inlet 11 of the compression section 10 and the reference opening 86.

Optionally, the reference connection 84 includes a throttle valve 85. The throttle valve 85 helps regulate the contact pressure.

The second oil inlet 81 of the second oil return 82 is arranged in a bottom area of the oil separator 45 . In particular, it is arranged below the first oil inlet 51 of the direct oil return 50 . In operation, if an oil level in the oil separator 45 drops to a level below the first oil inlet 51, the first oil inlet 51 will run dry and no longer be supplied with oil. However, the second oil inlet 81 is still supplied with oil. The oil supply of the second oil return thus enjoys priority over the oil supply of the direct oil return 50. This ensures that the contact pressure is maintained even if there is a lack of oil. A certain lubrication of the compression section 10 is maintained by the oil creeping past the orbiting disk 30 on the outside and by oil that returns to the inlet 11 of the compression section 10 through the external refrigerant circuit. In addition, oil from the compression chamber 80 can enter the compression section 10 through the reference connection 84, particularly when an oil level in the compression chamber is very high. The scroll compressor 1 further includes an electric motor and an inverter for the electric motor (not shown). The scroll compressor 1 can be integrated into a refrigerant circuit of a vehicle. The scroll compressor 1 can be installed in an electric vehicle or a hybrid vehicle, for example.

5 shows a longitudinal section of a compression section 10, a discharge pressure chamber 40, an oil separator 45 and a direct oil return 50 for directly returning oil from the oil separator 45 to the compression section 10 according to a second embodiment of a scroll compressor according to the invention. The remaining elements of this scroll compressor are not shown. Unless otherwise stated, the scroll compressor and its components correspond to the design and functioning of the scroll compressor 1 from FIG. 1 . The same reference numbers are used for the same elements.

Fig. 6 shows a cross section on line A in Fig. 5.

It is shown in FIGS. 5 and 6 that the outgassing chamber 54 is formed outside of the outlet pressure chamber 40 in the radial direction (perpendicular to the central axis of the stationary disk 20 ) and encloses the outlet pressure chamber 40 . The outgassing chamber 54 has an (at least essentially) hollow-cylindrical basic shape. The outlet pressure chamber 40 has an (at least substantially) cylindrical basic shape. The outlet pressure chamber 40 and the outgassing chamber 54 are arranged coaxially. A hollow-cylindrical casing wall 41 of the outlet pressure chamber 40 separates the outlet pressure chamber 40 and the outgassing chamber 45 from one another. In this way, the otherwise unused space around the casing wall 41 is used in an advantageous manner. The outlet pressure chamber 40 is in direct fluid communication with the oil separator 45 via an opening 42. Similar to FIG. 1, a non-return device can optionally be formed at the outlet 11 of the compression unit 10 (not shown).

The described embodiments with the direct oil return 50 allow particularly efficient operation and are highly reliable.

Reference list:

I scroll compressor

10 compression section

I I Inlet (of the compression section)

12 outlet (of the compression section)

13 non-return device

14a, 14b, 14c compression space

20 stationary disc

21 stationary spiral

22 stationary floor space

24 inner end (of the stationary spiral)

25 outer end (of the stationary spiral)

26 compressor channel (of the stationary disk)

28 outlet opening (of the stationary disk)

30 Orbiting Disc

31 orbiting spiral

32 orbiting footprint

34 outer end (of the orbiting spiral)

40 outlet pressure chamber

41 mantle wall

42 opening

45 oil separator

46 Oil Separator Outlet Port

50 direct oil return

51 first oil inlet

52 first fluid connection

53 first flow valve (throttle valve)

54 outgassing chamber

55 oil inlet

56 second fluid connection 57 second flow valve (throttle valve)

58 branch

59a, 59b orifice (of direct oil return)

70 fluid return

71 fluid inlet

72a, 72b orifice (of the fluid return)

80 compression chamber

81 second oil inlet

83 flow valve (throttle valve)

84 reference connection

85 flow valve (throttle valve)

86 reference opening

90 housing

91 intake port

92 outlet port

93 suction pressure chamber

AM,1,AM,2,AM,3,AM,4 area

El , £2, Emin, Smax position angle

El ,max, S2,min position angle

Y position angle of the outer end of the compressor duct

9 position angles

RI(Y) radial distance of the inside of the stationary scroll at the outer end of the compressor duct

BK width of the compressor duct in the radial direction at the outer end of the compressor duct RA(9 - 360°) radial distance of the outside of the stationary scroll at the position angle 9 - 360

Claims

62 patent claims:

1 . A scroll compressor (1) for compressing a fluid, comprising: having a compression section (10).

• an inlet (11) of the compression section (10) for sucking the fluid into the compression section (10),

• an outlet (12) of the compression section (10) for expelling the compressed fluid from the compression section (10),

• a stationary disc (20) with a stationary spiral (21), and

• an orbiting disk (30) with an orbiting spiral (31), wherein the orbiting disk (30) can be orbited relative to the stationary disk (20) along a compression direction (100) in order to extract the fluid from the inlet (11) of the compression section (10 ) conveying to the outlet (12) of the compression section (10) and thereby compressing; and an oil separator (45) for separating oil from the compressed fluid; wherein the scroll compressor (1) additionally has a direct oil return (50) for the direct return of oil from the oil separator (45) into the compression section (10), the direct oil return (50) having at least one orifice (59a, 59b), wherein the direct oil return (50) includes a first flow control valve (53), characterized in that the direct oil return (50) includes an outgassing chamber (54) located between the first flow control valve (53) and the orifice (59a, 59b) of the direct oil return (50) is arranged, and 63 that the scroll compressor (1) has a fluid return (70) for returning fluid from the outgassing chamber (54) into the compression section (10).

2. Scroll compressor (1) according to claim 1, characterized in that the orifice (59a, 59b) of the direct oil return (50) is arranged in the stationary disk (20).

3. Scroll compressor (1) according to claim 2, wherein the stationary disk (20) has a stationary scroll (21) which is arranged on a stationary base surface (22) of the stationary disk (20) and forms a spiral-shaped compressor channel (26) of the stationary disk (20). , characterized in that the orifice (59a, 59b) of the direct oil return (50) is arranged in an intake area of the compressor channel (26), which during operation is at least temporarily in direct fluid communication with the inlet (11) of the compression section (10) and / or outside of the compressor channel (26) is arranged.

4. Scroll compressor (1) according to one of the preceding claims, wherein the stationary disk (20) has the stationary scroll (21) which is arranged on the stationary base surface (22) of the stationary disk (20) and forms the spiral-shaped compressor channel (26), characterized in that that the orifice (59a, 59b) of the direct oil return (50) is located either at a position angle in a range of y - 30° and y + 30°, where y is a position angle of an outer end of the compressor duct (26), and is arranged at a radial distance RM,I from a center of the stationary disk (20), where RM,I lies in a range between (Ri(y) - BK) and Ri(y), where Ri(y) is a radial distance one inside of the 64

Stationary volute (21) is at an outer end of the compressor duct (26) and BK is a width of the compressor duct (26) along the radial direction at the outer end of the compressor duct (26), or outside the stationary volute (21) and at a position angle im range from 9 - 30° to Q + 30°, and is located at a radial distance RM,2 from the center of the stationary disk (20), where Q = y + 180° and RM,2 in a range from RA(9 - 360°) to RA(9-360°) + BK, where RA(9-360°) is a radial distance of an outside of the stationary scroll (21) at the position angle 9-360°.

5. Scroll compressor (1) according to one of the preceding claims, wherein in the compression mode between the orbiting scroll (31) and the stationary scroll (21) at least one compression chamber ° (14a, 14b, 14c) is formed, characterized in that the at least one orifice ( 59a, 59b) is never swept over by any compression space°(14a, 14b, 14c).

6. Scroll compressor (1) according to any one of the preceding claims, characterized in that the direct oil return (50) comprises a second flow control valve (57) which is arranged after the outgassing chamber (54).

7. Scroll compressor (1) according to one of the preceding claims, characterized in that the scroll compressor (1) is set up so that in compression operation the intermediate pressure in the outgassing chamber (54) is in a range from 0.2 bar to 6 bar above an intake pressure of the compression section (10).

8. Scroll compressor (1) according to any one of the preceding claims, characterized in that the scroll compressor (1) has an outlet pressure chamber (40) 65, wherein the oil separator (45) is in direct fluid communication with the outlet (12) of the compression section (10) via the outlet pressure chamber (40).

9. Scroll compressor (1) according to claim 5 and 8, characterized in that the outgassing chamber (54) is formed in the radial direction outside of the outlet pressure chamber (40) and encloses the outlet pressure chamber (40).

10. Scroll compressor (1) according to one of the preceding claims, characterized in that the scroll compressor (1) further comprises: a contact pressure chamber (80) which is subjected to a contact pressure in compression operation, the orbiting disc (30) being pressed against the surface by the contact pressure stationary disk (20) is pressed; and a second oil return (82) for returning oil from the oil separator (45) to the contact pressure chamber (80).

11. Scroll compressor (1) according to claim 10, characterized in that the second oil return (82) has priority over the direct oil return (50) in the event of a lack of oil.

12. Scroll compressor (1) according to claim 10 or 11, characterized in that the direct oil return (50) has a first oil inlet (51) which opens into the oil separator (45) and that the second oil return (82) has a second Oil inlet (81) which opens into the oil separator (45), the first oil inlet (51) being arranged above the second oil inlet (81).

13. Scroll compressor (1) according to any one of claims 10 to 12, characterized in that the scroll compressor (1) has a reference opening (86) which is arranged in the compression section (10), and one 66

Reference connection (84) which forms a fluid connection between the contact pressure chamber (80) and the reference opening (86) for influencing the contact pressure based on a reference pressure applied to the reference opening (86) during operation.

14. Scroll compressor (1) according to one of the preceding claims, characterized in that the outgassing chamber (54) has a volume in the range from 30 cm ³ to 150 cm ³ .

15. Scroll compressor (1) according to one of the preceding claims, characterized in that an orifice (72a) of the fluid return (70) is arranged in a central region of the compressor channel (26) of the stationary disk (20), the central region of the compressor channel (26 ) composed of all areas of the compressor channel (26) that can be in direct fluid connection neither with the inlet (11) of the compression section (10) nor with the outlet (12) of the compression section (10).