Scroll compressor

Abstract

A scroll compressor is provided that can effectively prevent strong contact between the wrap of a movable scroll and an end plate of a stationary scroll without deteriorating function and improve durability. A compression chamber 34, which is formed between the wraps 24, 32 of a stationary scroll 21 and a movable scroll 22 and is displaced from the outside to the inside while being reduced in size, compresses a working fluid. The wrap 32 of the movable scroll 22 has an inclined section in a region from a point P1 at which a line L1 extending from the center O of a scroll base circle through an involute start point S of an outer wall to the outside intersects the outermost wrap 32 to a wrap end point P2, where its height gradually decreases toward the wrap end point P2.

Description

TECHNICAL FIELD

[0001] The present invention relates to a scroll compressor which compresses a working fluid in a compression chamber formed between the turns of the scrolls by orbiting a movable scroll with respect to a stationary scroll. STATE OF THE ART

[0002] Typically, scroll compressors are designed in such a way that they comprise a compression mechanism with a stationary scroll with spiral turns on the surface of an end plate and a movable scroll with spiral turns on the surface of an end plate. By opposing the scroll turns, a compression chamber is formed between the turns. By setting the movable scroll in a circular orbital motion with respect to the stationary scroll by a motor, a working fluid (refrigerant) is compressed by displacing the compression chamber while reducing its volume from the outside to the inside.

[0003] Typically, contact between metals (aluminum) is prevented by installing a plastic tip seal at the tip end of the coil of both or one of the stationary scroll and the moving scroll. However, if no tip seal is provided, in an operating situation with repeated stopping and restarting of the scroll compressor, the start-up occurs with the moving scroll tilting (inclining). Therefore, it is conceivable that the coil tip end of the moving scroll is in contact with the end plate of the stationary scroll with high force until the start-up process stabilizes, resulting in the grinding of a groove on the end plate of the stationary scroll, particularly near the coil end where the coil has a thin wall thickness and the surface pressure increases slightly.

[0004] If this situation is repeated, the metallization near the winding end of the movable spiral wears out, resulting in high contact resistance between the metal spirals and the problem of fatigue damage (wall cracks or fractures) due to stress. LIST OF REFERENCE DOCUMENTSPATENT DOCUMENTS

[0005] Patent document 1: JP 4545039 B2 SUMMARY OF THE INVENTIONOBJECTS OF THE INVENTION

[0006] Therefore, it is conceivable, for example, to reduce the winding end section of the winding of the movable spiral in steps, but this has the disadvantage that the surface pressure increases in the corner section at the connection point between the steps, which leads to local detachment of the metallization.

[0007] It is also conceivable to gradually reduce the height of the outermost side of the coil of the movable scroll, as in Patent Document 1, for example. However, the amount of the coil height reduction is not clearly specified in Patent Document 1, and if it is too large, the scroll compressor function will be lost. Conversely, if the amount is too small, the actual wear of the scroll cannot be counteracted, so the occurrence of the strong contact state cannot be effectively prevented, and durability will be compromised.

[0008] The present invention has been made to solve these technical problems of the prior art, and has an object to provide a scroll compressor which can effectively prevent strong contact between the turn of the movable scroll and the end plate of the stationary scroll and improve durability without deteriorating the function. SOLUTION OF THE TASKS

[0009] To achieve the above object, a scroll compressor of the present invention comprises a compression mechanism having a stationary scroll and a movable scroll formed by opposing spiral turns on respective surfaces of respective end plates, wherein the movable scroll is driven into a circular orbital motion with respect to the stationary scroll, and a compression chamber formed between the turns of the scrolls is displaced from the outside to the inside while being reduced in size, thereby compressing a working fluid, characterized in that the turn of the movable scroll has an oblique portion in a region from a point P1 at which a line L1 extending from the center of a scroll base circle through an involute start point of an outer wall to the outside intersects the outermost turn, to a turn end point P2,where its height gradually decreases towards the winding end point P2.

[0010] A scroll compressor of an invention of claim 2 is characterized in that, in the above invention, on the turn of the movable scroll, a first inclined portion at which the height gradually increases toward the turn end point P2, a flat portion at which the height does not change, and a second inclined portion at which the height gradually decreases toward the turn end point P2 are continuously formed with each other.

[0011] A scroll compressor of an invention of claim 3 is characterized in that in the above invention, the height of the turn of the movable scroll is reduced by 10 µm at the terminal end of the first inclined portion and is reduced by 50 µm at the terminal end of the second inclined portion.

[0012] A scroll compressor of an invention of claim 4 is characterized in that in the invention of claim 2, a length of the coil is set to be longer at the flat portion than at the first inclined portion and longer at the second inclined portion than at the flat portion.

[0013] A scroll compressor of an invention of claim 5 is characterized in that in the invention of claim 1 both scrolls have been subjected to metallization processing.

[0014] A scroll compressor of an invention of claim 6 is characterized in that in the invention of claim 1, a back pressure chamber is formed on a back surface of an end plate of the movable scroll, and a back pressure hole connecting the back pressure chamber and the compression chamber is continuously formed on the end plate of the movable scroll.

[0015] A scroll compressor of an invention of claim 7 is characterized in that in the above inventions, no tip seal is provided at winding tip ends of the stationary scroll and the movable scroll. EFFECTS OF THE INVENTION

[0016] According to the present invention, while maintaining the function of a scroll compressor, grinding at the end plate of the stationary scroll can be improved, and fatigue damage at the tip end near the winding end of the movable scroll can be effectively prevented, thereby increasing durability. Thus, a scroll compressor can be provided that achieves a balanced performance and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] They show: Fig. 1 is a vertical sectional view of a scroll compressor of an embodiment to which the present invention is applied; Fig. 2 a plan view of a movable scroll of the scroll compressor from Fig. 1 when viewed from the winding side; and Fig. 3 is an explanatory view of a winding height near a winding end of the movable scroll of Fig. 2. DESCRIPTION OF THE EMBODIMENTS

[0018] An embodiment of the present invention will be described in detail below based on the accompanying figures. Fig. 1 is a schematic sectional view of a scroll compressor 1 of an embodiment to which the present invention has been applied.

[0019] The scroll compressor 1 of the embodiment is used, for example, in a refrigerant cycle of an air conditioning device of an electric vehicle, and sucks in refrigerant as a working fluid of the air conditioning device, compresses it, and discharges it to a discharge line, and is a so-called horizontally arranged scroll compressor with an integral inverter, which includes a three-phase electric motor 2, an inverter 3 for driving the electric motor 2, and a compression mechanism 4 driven by the electric motor 2.

[0020] The scroll compressor 1 of the embodiment includes a stator casing 7 accommodating the electric motor 2 and a center casing 6, an inverter casing 8 mounted on an end wall 7A on one end side of the stator casing 7 and accommodating the inverter 3, and a rear casing 9 mounted on the other end side of the stator casing 7.

[0021] The stator housing 7, the inverter housing 8 and the rear housing 9 are each made of metal (in the embodiment of aluminum), and by integrally joining them together, the housing 11 of the scroll compressor 1 of the embodiment is formed.

[0022] A motor chamber 12 is formed inside the stator housing 7, which accommodates the electric motor 2. One end surface of the motor chamber 12 is generally closed by an end wall 7A of the stator housing 7. The end wall 7A is a partition wall separating the motor chamber 12 and an inverter accommodating portion 13. The other end surface of the motor chamber 12 is open, and after accommodating the electric motor 2, the center housing 6 is accommodated through this opening. A subshaft bearing 16 is attached to the inner surface of the end wall 7A (on the motor chamber 12 side) to rotatably support one end portion of a drive shaft 14 of the electric motor 2.

[0023] A side of the central casing 6 opposite the electric motor 2 (other end side) is opened, and when a movable scroll 22 of the scroll compression mechanism 4, described below, has been received through this opening, the rear casing 9, to which a stationary scroll 21 of the scroll compression mechanism 4, also described below, is fixed, is fixed to the stator housing 7 and closes it.

[0024] A through hole 17 is provided on the central housing 6 through which the other end portion of the drive shaft 14 of the electric motor 2 is passed, and a main shaft bearing 18 is mounted in the central housing 6 on the side of the through hole 17 on the scroll compression mechanism 4 side, which main shaft bearing 18 rotatably supports the other end portion of the drive shaft 14 on the scroll compression mechanism 4 side.

[0025] The electric motor 2 is formed of a stator 25, around which a coil is wound and which is fixed to the inner peripheral wall of the stator housing 7, and a rotor 23 rotating on the inner side of the stator housing 7. For example, when direct current from a vehicle battery (not shown) is converted into three-phase current by the inverter 3 and the coil of the stator 25 of the electric motor 2 is supplied with current, the rotor 23 is driven to rotate. The drive shaft 14 is fixed to the rotor 23.

[0026] A suction port 20 is formed on the stator housing 7, and refrigerant sucked through the suction port 20 passes through the electric motor 2 in the stator housing 7, flows into the central housing 6, and is then sucked into a suction portion 37 on the outside of the scroll compression mechanism 4. Thus, the electric motor 2 is cooled by sucked refrigerant. Refrigerant compressed by the scroll compression mechanism 4 is discharged from a discharge chamber 27 described below from a discharge port 30 formed in the rear housing 9 to a discharge line of a refrigerant circuit (not shown) outside the housing 11.

[0027] The scroll compression mechanism 4 is formed by the stationary scroll 21 and the movable scroll 22. The stationary scroll 21 integrally comprises a circular disk-shaped end plate 23 and a spiral coil 24 formed by an involute-shaped or approximately involute curve projecting from the surface (a face) of the end plate 23. The surface of the end plate 23 on which the coil 24 projects is fixed to the rear casing 9 as a side of the central casing 6.

[0028] No tip seal is provided at a tip end of the coil 24 of the stationary scroll 21 of the embodiment. The surface of the end plate 23 and the coil 24 was subjected to tin plating in the embodiment. A discharge hole 26 is formed in the center of the end plate 23 of this stationary scroll 21, and the discharge hole 26 communicates with the discharge chamber 27 in the rear housing 9. Reference numeral 28 denotes a discharge valve provided at an opening on the rear side (other surface) of the end plate 23 at the discharge hole 26.

[0029] The movable scroll 22 is a scroll that rotates with respect to the stationary scroll 21 and integrally comprises a circular disk-shaped end plate 31, a spiral turn 32 formed by an involute-shaped or approximately involute curve projecting from the surface (one face) of the end plate 31, and a projection 33 projecting from the rear surface (other face) of the end plate 31 in the center.

[0030] Also, no tip seal is provided at a tip end of the coil 32 of the movable scroll 22 of the embodiment. The surface of the end plate 31 and the coil 32 was subjected to electroless plating with nickel and phosphorus in the embodiment. In the movable scroll 22, the coil 32 faces the coil 24 of the stationary scroll 21, with the protrusion direction of the coil 32 being the side with the stationary scroll 21, and they are arranged in an intermeshing manner, and a pressure chamber 34 is formed between the coils 24 and 32.

[0031] That is, the turn 32 of the movable scroll 22 faces the turn 24 of the stationary scroll 21, and they are engaged with each other such that the front end of the turn 32 contacts the surface of the end plate 23 and the front end of the turn 24 contacts the surface of the end plate 31. An eccentric portion 36 is fitted to the projection 33 of the movable scroll 22 and provided at the other end of the drive shaft 14 offset from the axis center. The movable scroll 22 is configured such that it does not rotate when the drive shaft 14 is rotated together with the rotor 23 of the electric motor 2, but instead orbits the stationary scroll 21.

[0032] Since the movable scroll 22 rotates eccentrically with respect to the stationary scroll 21, the contact position of the coils 24, 32 shifts in the eccentric direction as it rotates, and the pressure chamber 34 containing the refrigerant drawn in from the intake section 37 gradually decreases in size as it shifts inward. As a result, the refrigerant is compressed and finally discharged from the central discharge hole 26 to the discharge chamber 27 via the discharge valve 28.

[0033] In Fig. 1, 38 denotes an annular pressure plate. The pressure plate 38 partitions a back pressure chamber 39 formed between the rear surface of the end plate 31 of the movable scroll 22 and the central housing 6 and the suction portion 37 on the outside of the scroll compression mechanism 4, lies on the outside of the boss 33, and is provided between the central housing 6 and the movable scroll 22. 41 denotes a sealing member attached to the rear surface of the end plate 31 of the movable scroll 22 and abutting against the pressure plate 38, and the back pressure chamber 39 and the suction portion 37 are partitioned by the sealing member 41 and the pressure plate 38.

[0034] 48 denotes a centrifugal oil separator mounted in the discharge chamber 27 of the rear housing 9 (casing 11). This oil separator 48 serves to separate lubricating oil mixed with the refrigerant discharged from the scroll compression mechanism 4 into the discharge chamber 27 from the refrigerant. An inlet port 49 is formed in the oil separator 48, and the oil-containing refrigerant flowing in through this inlet port 49 is swirled in the oil separator 48. Due to the resulting centrifugal force, the oil is separated, and the refrigerant moves through an outlet port at the top to the discharge port 30 and is discharged to the discharge line as discussed.

[0035] An oil collection chamber 44 is formed below the oil separator 48 in the rear housing 9, and the oil separated from the refrigerant in the oil separator 48 flows from the lower end of the oil separator 48 into the oil collection chamber 44. Reference numeral 43 denotes a backpressure channel formed extending from the rear housing 9 to the central housing 6. The backpressure channel 43 is a passage that connects the oil separator 48 in the discharge chamber 27 in the rear housing 9 (on the discharge side of the scroll compression mechanism 4) and the backpressure chamber 39, and in the exemplary embodiment has a nozzle 50. In this way, the backpressure chamber 39, together with the oil separated at the oil separator 48 from the oil collection chamber 44, is subjected to the discharge pressure regulated by the nozzle 50 of the backpressure channel 43.

[0036] This counterforce (backpressure) in the backpressure chamber 39 generates a backpressure load that presses the movable scroll 22 against the stationary scroll 21. The backpressure load presses the movable scroll 22 against the backpressure from the pressure chamber 34 of the scroll compression mechanism 4 against the stationary scroll 21, so that contact between the coils 24, 32 and the end plates 31, 23 is maintained and the refrigerant in the pressure chamber 34 can be compressed.

[0037] Furthermore, in the exemplary embodiment, a backpressure hole 5 is provided at two locations in the end plate 31 of the movable scroll 22, connecting the backpressure chamber 39 and the compression chamber 34. The backpressure hole 5 serves to allow the pressure (refrigerant and oil) from the backpressure chamber 39 to escape into the compression chamber 34 when the pressure (backpressure) in the backpressure chamber 39 becomes too high.

[0038] The converter housing 8, in turn, is formed by a housing base body 10, which forms the converter receiving section 13 for receiving the converter 3, and a cover element 15 that closes an opening on an end surface of the housing base body 10. The cover element 15 is attached to the housing base body 10 after the converter 3 has been received in the converter receiving section 13.

[0039] A hermetic plate 52 is attached to the end wall 7A of the stator housing 7 (partition wall), and an electrically conductive hermetic pin 53 is attached to the hermetic plate 52. One end of the hermetic pin 53 extends through the end wall 7A into the motor chamber 12 and is connected to the coils of the stator 25 of the electric motor 2. The other end of the hermetic pin 53 is electrically connected to the circuit board 51 through a press-fit terminal 56.

[0040] Next, with reference to Fig. 2 and Fig. 3, the shape of the tip end portion of the winding 32 of the movable scroll 22 of the embodiment is described in detail. Fig. Fig. 2 is a plan view of the movable spiral 22 from the side of the winding 32 (surface side) and Fig. 3 is an explanatory view of the height near a winding end of the winding 32.

[0041] In Fig. 2, O denotes the center of a spiral base circle of the turn 32 of the movable spiral 22, and S denotes an involute starting point of an outer wall of the turn 32. If a line extending from the center O of the spiral base circle through the involute starting point S of the outer wall of the movable spiral 22 to the outside is L1, then a point at which the line L1 and the outermost turn 32 intersect is P1. P2 is the turn end point of the turn 32.

[0042] In the present invention, an inclined portion is formed on the winding 32 in the range from point P1 to the winding end point P2, the height of which gradually decreases toward the winding end point P2. In the case of the exemplary embodiment, the inclined portion comprises a first inclined portion 32A, the height of which gradually increases toward the winding end point P2, and a second inclined portion 32B, the height of which also gradually decreases toward the winding end point P2. A flat portion 32C, the height of which does not change, is formed between the first and second inclined portions 32A, 32B. In the winding 32 of the exemplary embodiment, in the range from point P1 to the winding end point P2, the first inclined portion 32A, the flat portion 32C, and the second inclined portion 32B are continuously formed from point P1.

[0043] If, as in Fig.3, a starting end of the first oblique section 32A is P3, a terminal end of the first oblique section 32A, i.e. a starting end of the flat section 32C is P4, a terminal end of the flat section 32C, i.e. a starting end of the second oblique section 32B is P5 and a terminal end of the second oblique section 32B is P6, the following relationship results for the length of the turn 32: length of the first oblique section 32A from P3 to P4 < length of the flat section 32C from P4 to P5 < length of the second oblique section 32B from P5 to P6.

[0044] The length of the turn 32 of the movable spiral 22 is thus set such that it is longer at the flat portion 32C than at the first inclined portion 32A, and longer at the second inclined portion 32B than at the flat portion 32C. The height of the turn 32 of the movable spiral 22 in the exemplary embodiment is 10 µm less at the terminal end P4 of the first inclined portion 32A (starting end of the flat portion 32C) than at the starting end P3 (normal height of the turn 32), and 50 µm less at the terminal end P6 of the second inclined portion 32B than at the starting end P3.

[0045] As discussed above, if no tip seal is provided at the tip end of the coil 32, as in the exemplary embodiment, in an operating situation with repeated stopping and restarting of the scroll compressor 1, the start occurs with tilting (inclination) of the movable scroll 22, which is why it is conceivable that the tip end of the coil 32 of the movable scroll 22 is in contact with the end plate 23 of the stationary scroll 21 with high force until the start-up process stabilizes. Therefore, in particular, near the coil end where the coil 32 has a small wall thickness and the surface pressure increases slightly, a groove is ground in on the end plate 23 of the stationary scroll 21.

[0046] If the height of the coil 32 is reduced to prevent the strong contact and the amount of height reduction is too large, the function as a scroll compressor 1 will be lost. On the other hand, if the amount is too small, the occurrence of the strong contact state between the end plate 23 of the stationary scroll 21 and the coil 32 of the movable scroll 22 cannot be effectively prevented, so that the durability is impaired.

[0047] However, as in the present invention, by forming the turn 32 of the movable scroll 22 in a region from the point P1 at which the line L1 extending from the center point O of the scroll base circle through the involute starting point S of the outer wall intersects the outermost turn 32 to the turn end point P2 the inclined portion where its height gradually decreases toward the turn end point P2, and by continuously forming the first inclined portion 32A where the height gradually increases toward the turn end point P2, the flat portion 32C where the height does not change, and the second inclined portion 32B where the height gradually decreases toward the turn end point P2, in this region, the grinding on the end plate 23 of the stationary scroll 21 can be improved while maintaining the function as a scroll compressor 1.The occurrence of fatigue damage at the head end near the winding end of the winding 32 of the movable scroll 22 can also be effectively prevented. Therefore, durability can be increased, and function and durability can be achieved in a balanced manner.

[0048] In the turn 32 of the movable scroll 22 of the embodiment, the first inclined portion 32A, where the height gradually increases toward the turn end point P2, the flat portion 32C, where the height does not change, and the second inclined portion 32B, where the height gradually decreases toward the turn end point P2, are formed continuously with each other, but this is not limited to this, and in the range from the point P1 at which the line L1, which extends from the center O of the scroll base circle through the involute start point S of the outer wall to the outside, intersects the outermost turn 32, to the turn end point P2, a series of inclined portions (without a flat portion) in which the height gradually decreases toward the turn end point P2 may be formed, or more inclined portions and flat portions may be formed than in the embodiment.

[0049] In the exemplary embodiment, the present invention is applied to a scroll compressor 1 used in a refrigerant cycle of a vehicle air conditioning device, but it is not limited thereto, and the present invention is effective for scroll compressors used in refrigerant cycles of various refrigeration devices. Also, in the exemplary embodiment, the present invention is applied to a so-called scroll compressor with an integrally formed inverter, but it is not limited thereto, and it can also be applied to a scroll compressor without an integral inverter. LIST OF REFERENCE SYMBOLS 1 scroll compressor 2 electric motor 4 Spiral compression mechanism (compression mechanism) 5 counterpressure hole 11 housings 21 stationary spiral 22 movable spiral 23, 31 end plate 24, 32 turns 32A first inclined section 32B second oblique section 32C flat section L1 Line running from the center point O of the spiral base circle through the involute starting point S of the outer wall of the movable spiral 22 outwards O Center of the spiral base circle of turn 32 of the movable spiral 22 P1 Intersection of line L1 and the outermost turn 32 P2 winding end point of winding 32 S Involute starting point of the outer wall of the turn 32 QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 4545039 B2

[0005]

Claims

[1] A scroll compressor comprising a compression mechanism having a stationary scroll and a movable scroll formed by opposing spiral turns on respective surfaces of respective end plates, wherein the movable scroll is driven in a circular orbital motion with respect to the stationary scroll, and a compression chamber formed between the turns of the scrolls is displaced from the outside to the inside while being reduced in size, thereby compressing a working fluid, characterized by that the turn of the movable spiral in a region from a point P1 at which a line L1 running from the center of a spiral base circle through an involute start point of an outer wall to the outside intersects the outermost turn, to a turn end point P2 has an oblique section at which its height gradually decreases towards the turn end point P2. [2] Scroll compressor according to claim 1, characterized bythat on the winding of the movable spiral a first oblique section, at which the height gradually increases towards the winding end point P2, a flat section at which the height does not change, and a second oblique section, at which the height gradually decreases towards the winding end point P2, are formed continuously with one another. [3] Scroll compressor according to claim 2, characterized by that the height of the turn of the movable spiral is reduced by 10 µm at the terminal end of the first inclined section and by 50 µm at the terminal end of the second inclined section. [4] Scroll compressor according to claim 2, characterized by that a length of the turn is determined so that it is greater at the flat section than at the first inclined section and is greater at the second inclined section than at the flat section. [5] Scroll compressor according to claim 1, characterized by that both spirals were subjected to metallization processing. [6] Scroll compressor according to claim 1, characterized by that a back pressure chamber is formed on a back surface of an end plate of the movable scroll and a back pressure hole connecting the back pressure chamber and the compression chamber is continuously formed on the end plate of the movable scroll. [7] Scroll compressor according to one of claims 1 to 6, characterized by that no tip seal is provided at the winding head ends of the stationary scroll and the movable scroll.

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