SCROLLMASCHINE

Description

[0001] The invention relates to a scroll machine, e.g. in the form of a scroll compressor, which is used in particular for the compression of refrigerant in a vehicle air conditioning system.

[0002] Motor vehicles are regularly equipped with air conditioning systems that use a refrigerant circuit to cool the vehicle interior. These systems essentially consist of a closed loop containing a refrigerant. The refrigerant, for example R-744 (carbon dioxide, CO₂) or R-134a (1,1,1,2-tetrafluoroethane), is heated at an evaporator and compressed by a (refrigerant) compressor. The refrigerant then releases the absorbed heat via a heat exchanger before being returned to the evaporator through an expansion valve.

[0003] A so-called scroll compressor is frequently used to compress a refrigerant. The design and operation of such a scroll compressor, used for the refrigerant in a vehicle air conditioning system, is described, for example, in DE 10 2012 104 045 A1. Essential components of such a scroll compressor are two scrolls that can move relative to each other. The system usually also contains oil in droplet form or as a mist, which is at least partially separated from the (usually gaseous) refrigerant after compression. The refrigerant (possibly with residual oil) is then introduced into the air conditioning circuit, while the separated oil can usually be used within the scroll compressor to lubricate moving parts.

[0004] The scroll components are generally designed as a fixed scroll (displacement scroll) and a movable, orbiting scroll (counter-scroll, rotor scroll). Both scrolls are fundamentally identical in construction, each featuring a base plate (basic body, scroll disk) and a spiral wall (spiral wall, scroll wall) extending axially from the base plate. When assembled, the spiral walls of the two scrolls are nested within each other, forming multiple conveying chambers between the partially contacting scroll walls.

[0005] In this and the following, an orbiting motion is understood to mean, in particular, an eccentric, circular trajectory in which the moving scroll itself does not rotate around its own axis. During operation, the two scrolls maintain the smallest possible axial distance from each other. With each orbiting motion, essentially crescent-shaped (compressor or conveying) chambers are formed between the spiral walls. As the two scrolls move relative to each other (at least during a compression process), the volume of these chambers migrates from the outside along the spiral walls towards the central axis of the respective scroll, thereby progressively reducing the volume (and thus compressing the medium within).

[0006] Typically, an electric motor is provided to drive the movable scroll, the motor shaft of which is coupled to the movable scroll part by means of an (A-side) eccentric shaft journal (also: "shaft pin").

[0007] Due to manufacturing tolerances, including those of the two scroll contours, the actual eccentric raceway of the moving scroll typically deviates from an ideal eccentric raceway. To ensure the most consistent radial contact possible between the two scrolls, particularly their scroll walls, throughout the entire orbital movement, a unit rotatably mounted on the shaft journal (also known as an "eccentric unit" or "swing link") is usually employed. This swing link is mounted eccentrically relative to the shaft journal. Specifically, the shaft journal is eccentrically mounted in a bearing journal of the swing link, and the moving scroll is, in turn, rotatably mounted around the bearing journal, typically by means of a rolling bearing.

[0008] During compressor operation, tangential compression forces act on the walls (scroll walls) of the conveying chambers. These compression forces also act on the center of the bearing journal. These tangential compression forces must be balanced (especially to maintain operation) by a driving or counterforce. This counterforce acts at the center of the shaft journal. Due to the offset of the centers of the shaft and bearing journal, a torque is generated that causes the swing link to rotate around the shaft journal. Because of the eccentricity of the bearing journal relative to the shaft journal, this rotation also leads to a radial displacement of the bearing journal's center relative to the center of the motor shaft. In other words, this changes the so-called orbital radius and thus the radial distance between the spiral walls. The swing link therefore forms a radius compensation system.

[0009] Such scrolling machines are known, for example, from DE 10 2019 108 079 A1 and EP 3 159 544 A1.

[0010] The invention is based on the objective of improving a scrolling machine.

[0011] This problem is solved according to the invention by a scrolling machine with the features of claim 1. Advantageous and partly inventive embodiments and further developments of the invention are set out in the dependent claims and the following description.

[0012] The scroll machine according to the invention is designed and intended, in particular, as a scroll compressor and, within this context, preferably for the compression of refrigerant in a vehicle air conditioning system. For this purpose, the scroll machine comprises a first scroll with a first spiral wall projecting in an axial direction. Preferably, the first scroll comprises a first base plate from which the first spiral wall projects, thereby forming a first spiral turn, and a boundary wall (in particular, surrounding the spiral wall on the outside). The scroll machine also has a second scroll with a second spiral wall projecting in an axial direction. In particular, the second scroll also comprises a second base plate from which the second spiral wall projects.The second spiral wall engages the first spiral section eccentrically to the first scroll and, in normal operation, forms a number of conveying chambers (also referred to as "compressor chambers" in normal compressor operation) along the first spiral wall due to orbiting relative to the first scroll. The scroll machine also includes a drive – preferably electric – and a drive shaft by which the drive and the second scroll are mechanically coupled, particularly for power transmission. Furthermore, the scroll machine includes a radius compensation system located between the drive shaft and the second scroll.This radius compensation system features an eccentric (also known as a "swing link") that is coupled to the drive shaft by means of a shaft pin (or shaft journal) arranged eccentrically to the drive shaft, and to the second scroll by means of a bearing journal that is eccentric to the shaft pin. Preferably, the shaft pin is separate from the eccentric and the motor shaft, while the bearing journal is formed integrally (i.e., monolithically) with the eccentric. A bearing journal (center) axis (hereinafter referred to as "pin center") is arranged at a greater distance from the drive shaft (center) axis (hereinafter referred to as "shaft center") than a center axis of the shaft pin ("pin center").

[0013] The invention is based on the consideration that, during intended operation, particularly during compressor operation, a tangential force occurs due to the (fluid, especially gas) pressure present in the conveying or compressor chambers, which acts on the pin center. Due to the eccentricity of the pin center and the pin center, this tangential force results in a torque that rotates around the pin center. In the arrangement of the respective centers relative to each other described above, this torque acts, at least during compressor operation, against one direction of rotation of the drive shaft. Since the shaft pin is arranged at a smaller distance from the shaft center than the pin center, the arrangement described above creates space—particularly on the end face of the drive shaft—which can then be used to make the diameter of the shaft pin as large as possible.This in turn allows for a high, so-called (bending) resistance moment, which reflects the stiffness of the shaft pin against bending.

[0014] According to the invention, the shaft pin is also designed with a comparatively large (pin) diameter. Specifically, in this case, for a given load spectrum, the diameter of the shaft pin is larger compared to an arrangement in which the pin center is located at a greater distance from the shaft center than the pin center and which is designed for the same load spectrum.

[0015] Advantageously, a larger diameter of the shaft pin also allows for a better fit of the shaft pin in the corresponding mounting bore of the eccentric, particularly its bearing journal. This specifically reduces the Hertzian contact pressure, which in turn contributes to the durability of the shaft pin and / or eccentric, specifically its bearing journal. Furthermore, the larger diameter of the shaft pin also advantageously reduces dynamic imbalance during operation, as the increased bending moment of resistance allows for less bending of the shaft pin. This, in turn, results in less tilting and thus less displacement of the mass of the second scroll during operation.

[0016] In a preferred embodiment, increasing the diameter of the shaft pin is made possible, in particular, by arranging the shaft pin with the smallest possible edge distance to the drive shaft, expediently maintaining a minimum permissible edge distance. For example, the edge distance is the same as in an arrangement where the distance between the shaft center and the pin center is greater than the distance between the shaft center and the journal center. Optionally, however, the edge distance can even be reduced, since with an increased diameter of the shaft pin, the contact pressure between the drive shaft and the shaft pin for the required holding force (due to the larger frictional area) can be kept lower, thus reducing the load on the shaft. Preferably, the shaft pin is manufactured separately and inserted into the drive shaft, expediently by pressing it in.The term "minimum permissible edge distance" refers in particular to a value at which edge bulging of the drive shaft due to the press fit between the shaft pin and the drive shaft is avoided or at least kept within permissible limits – preferably even under intended load during operation. In other words, the diameter of the shaft pin is preferably selected, starting from a pitch circle of the drive shaft's end face on which the pin center should lie for sufficient power transmission to the second scroll, such that the smallest possible edge distance is maintained. Specifically, the diameter of the shaft pin is thus increased from the selected pitch circle to such an extent that the minimum permissible edge distance is not undercut.

[0017] Furthermore, the wave center, the cone center, and the pin center preferably form a triangle, meaning they do not lie on a common straight line.

[0018] In another practical embodiment, the eccentric with its bearing journal is supported in the second scroll by means of a standard bearing, in particular a standard rolling bearing (e.g., a ball bearing). In particular, no special bearing is used – especially compared to the arrangement where only a smaller diameter of the shaft pins is possible. Such a special bearing is usually required to compensate for or reduce any tilting or bending of the bearing journal relative to the drive shaft, which in turn results from bending of the shaft pin, with respect to the second scroll, so that the latter is not also tilted relative to the drive shaft and the first scroll. For example, in the case of a ball bearing, such a special bearing has a bearing ring with a raceway that has several different raceway radii side by side in the axial direction.Due to the increased stiffness of the shaft pin, such a (usually relatively expensive) special bearing is no longer necessary. This also demonstrably reduces manufacturing costs.

[0019] In a suitable design, the pin center is arranged in the intended direction of rotation (of the drive shaft, particularly during compressor operation) and, viewed from the shaft center, trails the journal center. For illustrative purposes only, the pin center (when viewed from the scroll towards the drive and in the case of the intended direction of rotation of the drive shaft counterclockwise) is located approximately at a "half past one" position, and the journal center roughly at a "twelve" o'clock position (and the shaft center at the origin of the hand). The force that must be applied by the shaft pin (especially to the bearing journal) is thus approximately tangential to the direction of rotation.Due to the shaft pin's "lagging" position relative to the journal center in the direction of rotation, the force exerted by the shaft pin is directed against the greatest possible wall thickness of the bearing journal (and optionally also the drive shaft). This, in turn, is advantageous for improved, and especially longer, durability (e.g., due to potential abrasion).

[0020] The direction of rotation is always understood here and in the following, in particular, by looking from an "A" side towards a "B" side of the drive, i.e., from the scroll towards the drive.

[0021] In another advantageous embodiment, the radius compensation system features a limiting pin, which is rigidly mounted, particularly in the drive shaft. This pin serves to limit the compensating movement of the eccentric and engages with it for this purpose. For example, the limiting pin is located in an elongated hole in the eccentric and / or a bore with a correspondingly larger diameter than the limiting pin. The rotation of the eccentric is thus determined by the difference between the length or diameter of this "limiting bore" and the diameter of the limiting pin. The shaft center is advantageously located between the limiting pin and the bearing journal axis, as well as the axis of the shaft pin.

[0022] The scroll machine is preferably used as a scroll compressor. In this case, the conveying chambers act as compressor chambers during normal (compressor) operation (as already indicated above), since their volume decreases progressively during operation. However, the scroll machine described here and below can also be used as an expander – particularly when the orbital direction is reversed – i.e., conveying from a high-pressure area to a low-pressure area. Especially if the scroll machine is electrically driven, generator operation is also possible, in which the scrolling motion is driven by the expansion of a medium within the conveying chambers.

[0023] Preferably, only one of the two scrolls orbits during normal operation, in particular the second scroll. In this case, the other, specifically the first scroll, is preferably designed as a fixed scroll. For simplicity, the second scroll will be referred to as the orbiting scroll (also: "O-scroll"). Similarly, the first scroll will also be referred to as the fixed scroll or "F-scroll" for the sake of simplicity.

[0024] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 schematically shows a scrolling machine in a perspective view, Fig. 2 schematically shows a longitudinal section of the scrolling machine in a partial sectional view, Fig. 3 shows a detailed view of Fig. 2 Fig. 4 schematically shows a section of a rotor of an electric motor and a first scroll of a compressor module of the scroll machine, and Fig. 4 schematically shows a part of a radial compensation system of the scroll machine in a view on a top side.

[0025] Corresponding parts in all figures are always marked with the same reference symbols.

[0026] Fig. 1 Figure 1 shows a scroll compressor, specifically a refrigerant compressor, installed in a refrigerant circuit (not shown) of a motor vehicle air conditioning system. The scroll compressor 2 is electrically driven and comprises an electric drive module 4 and a compressor module 6 coupled to it. A mechanical interface 8 is provided between the drive module 4 and the compressor module 6, by means of which the compressor module 6 is connected to the drive module 4. The compressor module 6 is connected to the drive module 4 by means of flange connections 10 distributed around its circumference and extending in an axial direction A of the scroll compressor 2; specifically, it is bolted to the drive module 4.

[0027] The drive module 4 has a drive housing 12 with an interior 12a (see Fig. 2 ) the compressor module 6 a compressor or "scroll housing 14" with a "scroll chamber 14a". An electric motor 16 is arranged in the interior 12a as a drive. A in Fig. 1 The housing section of the drive housing 12 shown below encloses an electronics compartment 12b (see below). Fig. 2 ), in which motor electronics (not shown) controlling the electric motor 16 are arranged.

[0028] The scroll compressor 2 has a (refrigerant) inlet 20 (or connection) for connection to the refrigerant circuit and a (refrigerant) outlet 22. The inlet 20 is formed in an area of ​​the drive housing 12 facing the electronics compartment 12b. The outlet 22 is formed on a "base 24" of the scroll housing 14. When connected, the inlet 20 forms the low-pressure or suction side (suction gas side) and the outlet 22 the high-pressure or pump side (pump side) of the scroll compressor 2.

[0029] As from Fig. 2 As can be seen, an "output-side" (A-side, arranged towards the downstream, driven elements) bearing shield 26 is arranged in the area of ​​the mechanical interface 8. This forms an intermediate wall, also referred to as a "center plate", between the drive module 4 and the compressor module 6.

[0030] As from Fig. 2 As can be further seen, the compressor module 6 of the scroll compressor 2 has a first, fixed scroll (scroll part, hereinafter referred to as fixed scroll, or "F-Scroll 28") arranged in the scroll housing 14 and a second, movable scroll (scroll part, hereinafter referred to as orbiting scroll, or "O-Scroll 30"). The O-Scroll 30 is connected by means of an eccentric, hereinafter referred to as "Swing Link 32", via a connecting pin or shaft journal (here: "shaft pin 34"; see also Fig. 3 ) is coupled to a (drive or motor) shaft 36 of the electric motor 16, which is guided in the bearing shield 26. A counterweight (here referred to as "balancing weight" 32a) is eccentrically connected to the swing link 32.

[0031] The swing link 32 is mounted in a rolling or ball bearing 38, which is held in the O-scroll 30, by means of a bearing journal 32b formed in one piece with the link. Another rolling or ball bearing 40 is arranged in the bearing shield 26 to support the shaft 36. The O-scroll 30 is driven in an orbiting motion by means of the shaft 36 and the shaft pin 34, which is eccentrically inserted into the shaft 36, during operation of the scroll compressor 2.

[0032] In contrast, the F-Scroll 28 is rigidly fixed within the scroll housing 14. Both scrolls 28 and 30 each have associated helical or spiral spiral walls 28a and 30a (scroll walls, scroll spirals) that project axially from a respective base plate 28b and 30b. The F-Scroll 28 also has a circumferential boundary wall 28c. In the assembled state, the spiral walls 28a and 30 of the two scrolls 28 and 30 interlock. Between the scrolls 28 and 30—that is, between their spiral walls 28a and 30a and the base plates 28b and 30b—conveyor or compressor chambers 42 are formed, the volume of which changes when the electric motor 16 is operated.

[0033] The Swing Link 32 forms a radial tolerance (or radius) compensation system and is in Fig. 4 The core function of the swing link 32 is to maintain a sealing radial fit between the two scrolls 28 and 30, even despite manufacturing tolerances, particularly of the two spiral walls 28a and 30a, which counteract such a fit. This function is explained in more detail below. Fig. 4 explained in more detail.

[0034] As described above, the swing link 32 is coupled to the shaft 36 by means of the shaft pin 34. For this purpose, the swing link 32 has a bore 44 which is eccentrically arranged in the bearing journal 32b. A journal center 46 of the bearing journal 32b (i.e., its axis) and a pin center 48 of the shaft pin 34 (as well as of the bore 44, i.e., its axis) are thus dissimilar. A shaft center 50 of the shaft 36 (i.e., its axis) is also offset from both the journal center 46 and the pin center 48.

[0035] The distance between the wave center 50 and the cone center 46 is chosen to be greater here than the distance between the wave center 50 and the pin center 48. Thus, the three points form a triangle (see figure). Fig. 4 dotted line). The distance between the shaft center 50 and the pin center 46 describes an orbital radius Ro with which the O-Scroll 30 orbits during compressor operation.

[0036] In the exemplary embodiment according to Fig. 4 Furthermore, pin center 48 and pivot center 46 are arranged such that pin center 48 lags behind pivot center 46 in the direction of rotation R of the shaft 36 (which, viewed from scroll space 14a towards the electric motor 16, runs counterclockwise) and from the shaft center 50. Figuratively speaking, pin center 48 is located roughly at a "half-at-one" position with respect to shaft center 50 as its origin, while bearing center 46 is located approximately at "twelve o'clock".

[0037] During compressor operation, the gas pressure in the compressor chambers 42 results in a tangential force Ft on the spiral walls 28a, 30a, which thus also acts on the pin center 46. A corresponding counterforce must be applied via the shaft 36 through the shaft pin 34 and therefore acts offset from the tangential force Ft at the pin center 48. Due to the offset between the pin center 46 and the pin center 48, the counterforce results in a resultant force Fr that is inclined to the counterforce (see figure). Fig. 4 (long-stroke force vector). Due to the arrangement of shaft center 50, pin center 46 and pin center 48 relative to each other described above, a resulting torque Mr is obtained here, which acts clockwise.

[0038] The Swing Link 32 is now connected by means of a limiting pin 52 (see below). Fig. 3 The shaft 36 is secured against rotation around the shaft pin 34. The limiting pin 52 is fixedly mounted in the shaft 36 and engages in a limiting bore 54 in the swing link 32. This limiting bore 54 has a larger diameter than the limiting pin 52, allowing a slight rotation of the swing link 32 around the shaft pin 34. As the tangential force Ft increases, the resulting torque Mr causes the swing link 32 to rotate clockwise, thus increasing the distance between the shaft center 50 and the journal center 46 and consequently increasing the orbital radius Ro. This maintains or improves the close fit between the O-scroll 30 and the F-scroll 28.

[0039] By choosing a smaller distance between shaft center 50 and pin center 48 than the orbital radius Ro (i.e., the distance between shaft center 50 and bearing center 46), the shaft pin 34, specifically its pin center 48, can be positioned closer to the shaft center 50. Compared to an arrangement of the shaft pin 34 with a greater distance to the shaft center 50 than to the bearing center 46 (standard arrangement), the diameter of the shaft pin 34 can thus be increased, particularly when designed for the same load spectrum, without falling below a minimum edge distance Am specified by the strength of the shaft 36. This edge distance Am limits the diameter of the shaft pin 34 in the standard arrangement. Fig. 4In the illustrated arrangement, the diameter of the shaft pin 34 can be increased (in particular, at least) up to the edge distance Am, so that the shaft pin 34 experiences a significant increase in strength (due to the corresponding increase in its bending section modulus). This reduces bending of the shaft pin 34 under load and thus also tilting of the swing link 32. Therefore, the ball bearing 38 can again be designed as a standard bearing, since it no longer needs to compensate for tilting.

[0040] Furthermore, in the direction of the resultant Fr, the material thickness between the shaft pin 34 and the edge of the shaft 36 is increased, so that fatigue phenomena (e.g. abrasion) of the shaft 36 and / or the bearing journal 35b) can be reduced or the time until their occurrence can be extended.

[0041] The subject matter of the invention is not limited to the embodiment described above. Rather, further embodiments of the invention can be derived by a person skilled in the art from the above description. 2Scroll compressor 4Drive module 6Compressor module 8Interface 10Flange connection 12Drive housing 12aInterior 12bElectronics compartment 14Scroll housing 14aScroll chamber 16Electric motor 20Inlet 22Outlet 24Base 26Bearing plate 28F-Scroll 28aSpiral wall 28bBase plate 30O-Scroll 30aSpiral wall 30bBase plate 32Swing link 32aBalancing weight 34Shaft pin 36Shaft 38Ball bearing 40Ball bearing 42Compressor chamber 44Bore 46Pitch center 48Pin center 50Shaft center 52Lift pin 54Lift bore AAxial direction FtTangential force FrResultant MResultant torque RRotation direction ROrbitation radius At the edge distance

Claims

1. Scroll machine (2), in particular for refrigerant of a vehicle air conditioning system, having - a first scroll (28) with a first spiral wall (28a) projecting in an axial direction (A), - a second scroll (30) with a second spiral wall (30a) projecting in the axial direction (A), - a drive (16), - a drive shaft (36), by means of which the drive (16) and the second scroll (30) are coupled in a power-transmitting manner, and - a radius compensation system (32) which is connected between the drive shaft (36) and the second scroll (30) and which has an eccentric (32) which is coupled by means of a shaft pin (34), arranged eccentrically with respect to the drive shaft (36), to the drive shaft (36) and by means of a bearing journal (32b), eccentric with respect to the shaft pin (34), to the second scroll (30), wherein a bearing journal axis (46) is arranged at a greater distance from the drive shaft axis (50) than an axis (48) of the shaft pin (34), characterized in that, for a predetermined load spectrum, a diameter of the shaft pin (34) is increased relative to an arrangement, in which the axis (48) of the shaft pin (34) is arranged at a greater distance than the bearing journal axis (46) and which is designed for the same load spectrum, is arranged from the drive shaft axis (50).

2. Scroll machine (2) according to Claim 1, wherein the shaft pin (34) is arranged on the drive shaft (36) at the smallest possible edge distance (Am).

3. Scroll machine (2) according to Claim 1 or 2, wherein the bearing journal axis (46), the drive shaft axis (50) and the axis (48) of the shaft pin (34) define a triangle.

4. Scroll machine (2) according to any one of Claims 1 to 3, wherein the eccentric (32) is mounted with its bearing journal (32b) in the second scroll (30) by means of a standard bearing, in particular a standard anti-friction bearing (38).

5. Scroll machine (2) according to any one of Claims 1 to 4, wherein the axis (48) of the shaft pin (34) is arranged so as to trail the bearing journal axis (46) in an intended direction of rotation (R) and as viewed from the drive shaft axis (50).

6. Scroll machine (2) according to any one of Claims 1 to 4, wherein the radius compensation system (32) has a limiting pin (52), which is rigidly supported in particular in the drive shaft (36) and which is in engagement with the eccentric (32) in order to limit a compensating movement of the latter, and wherein the drive shaft axis (50) is arranged between the limiting pin (52) and the bearing journal axis (46) as well as the axis (48) of the shaft pin (34).