Scroll compressor

Abstract

The present invention provides a scroll compressor, and the problem is to efficiently discharge a liquid refrigerant from a compression mechanism while suppressing the load applied to each of a fixed scroll wall and an orbiting scroll wall. The control unit (60) executes a start-up operation prior to execution of a normal operation for driving the motor (22), executes a reversal start-up in which the motor (22) is reversed while the bush (51) is swung so that the revolution radius of the orbiting scroll (26) is reduced and the gap between the fixed scroll wall (25b) and the orbiting scroll wall (26b) becomes large, and executes a reverse start-up in which the motor (22) is swung so that the gap between the fixed scroll wall (25b) and the orbiting scroll wall (26b) becomes large after execution of the reversal start-up. When the rotation speed of the motor (22) reaches a predetermined rotation speed, the motor (22) is driven to rotate forward to maintain the orientation of the bushing (51) while the rotational acceleration of the motor (22) is reduced compared to when the reverse start is being executed. A liquid discharge start is executed in which the motor (22) is driven at a predetermined rotational speed so that the liquid refrigerant is discharged from the compression mechanism (C1) and the orbiting scroll (26) revolves.

Description

Technical Field

[0001] The present invention relates to a scroll type compressor. Background Art

[0002] A scroll compressor includes a housing, a rotating shaft, a motor, and a compression mechanism. The rotating shaft is supported on the housing in a manner that allows it to rotate relative to the housing. The motor rotates the rotating shaft. The compression mechanism is driven by the motor. The compression mechanism compresses the refrigerant. The compression mechanism includes a fixed scroll and a swirling scroll. The fixed scroll has a disc-shaped fixed base plate and a fixed scroll wall. The fixed scroll wall rises from the fixed base plate. The swirling scroll has a disc-shaped swirling base plate and a swirling scroll wall. The swirling base plate is opposite to the fixed base plate. The swirling scroll wall rises from the swirling base plate toward the fixed base plate. The swirling scroll wall meshes with the fixed scroll wall. Furthermore, the swirling scroll compresses the refrigerant together with the fixed scroll due to the rotation of the rotating shaft.

[0003] In addition, as in Patent Document 1, for example, an eccentric shaft is provided on the rotating shaft. The eccentric shaft extends parallel to the axis of the rotating shaft at a position eccentric to the axis of the rotating shaft. A bushing is inserted into the eccentric shaft. The bushing is capable of swinging around the eccentric shaft. Furthermore, the orbital radius of the orbiting scroll is variable according to the swinging of the bushing around the eccentric shaft.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 8-159052 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In such a scroll compressor, the refrigerant may sometimes be cooled and liquefied when the scroll compressor is stopped. Thus, if the scroll compressor is started in a state where liquid refrigerant generated by the liquefaction of the refrigerant exists, liquid compression may occur in the compression mechanism when the liquid refrigerant is discharged from the compression mechanism. If liquid compression occurs in the compression mechanism, loads are applied to the fixed scroll wall and the orbiting scroll wall, respectively, potentially causing undesirable conditions such as deformation of the fixed scroll wall and the orbiting scroll wall. Therefore, it is desirable to efficiently discharge liquid refrigerant from the compression mechanism while suppressing the loads applied to the fixed scroll wall and the orbiting scroll wall when the scroll compressor is started.

[0009] Means for solving problems

[0010] The scroll compressor for solving the above problems comprises: a housing; a rotating shaft supported by the housing in a manner capable of rotating relative to the housing; a motor for rotating the rotating shaft; a control unit for controlling the driving of the motor; and a compression mechanism driven by the motor and compressing the refrigerant, wherein the compression mechanism comprises: a fixed scroll having a disk-shaped fixed base plate and a fixed scroll wall rising from the fixed base plate; and an orbiting scroll having a disk-shaped orbiting base plate opposite to the fixed base plate and an orbiting scroll wall rising from the orbiting base plate toward the fixed base plate and meshing with the fixed scroll wall, wherein the refrigerant is compressed together with the fixed scroll by the rotation of the rotating shaft, The diameter is variable according to the swing of the sleeve centered on the eccentric shaft. The scroll compressor is characterized in that the control unit performs a starting operation to discharge liquid refrigerant from the compression mechanism before performing normal operation to drive the motor. During the starting operation, a reverse start is performed to swing the sleeve and reverse the motor in a manner that reduces the orbital radius of the orbiting scroll and increases the gap between the fixed scroll wall and the orbiting scroll wall. After performing the reverse start, a forward start is performed to reduce the rotational acceleration of the motor compared to when the reverse start is performed and to rotate the motor in the forward direction while maintaining the posture of the sleeve. When the forward start is performed and the speed of the motor reaches a predetermined speed, a liquid discharge start is performed to drive the motor at the predetermined speed in a manner that causes the liquid refrigerant to be discharged from the compression mechanism and to perform the orbital motion of the orbiting scroll.

[0011] Thus, the control unit performs a starting operation to discharge liquid refrigerant from the compression mechanism before performing normal operation of the drive motor. In the starting operation, the control unit first performs a reverse start. If the reverse start is performed, the motor reverses, and thereby the bushing swings in such a manner that the orbital radius of the orbiting scroll is reduced and the gap between the fixed vortex wall and the orbiting vortex wall becomes larger. In this way, before performing normal operation, the gap between the fixed vortex wall and the orbiting vortex wall is large. Then, after performing the reverse start, the control unit performs a forward start. In the forward start, the rotational acceleration of the motor is reduced compared to when the reverse start is performed, thereby maintaining the posture of the bushing even if the motor is accelerated in a forward manner. Therefore, even if the motor is accelerated in a forward manner, the gap between the fixed vortex wall and the orbiting vortex wall is maintained in a large state. When the motor reaches a predetermined speed during forward start-up, the control unit executes a liquid discharge start, driving the motor at a predetermined speed to cause the orbiting scroll to orbit, discharging liquid refrigerant from the compression mechanism. This allows the orbiting scroll to orbit with a large gap between the fixed and orbiting scrolls, making liquid compression less likely to occur in the compression mechanism. As a result, liquid refrigerant can be efficiently discharged from the compression mechanism while minimizing the loads applied to the fixed and orbiting scrolls.

[0012] In the scroll compressor described above, preferably, during the reverse start-up, the control unit causes the bushing to swing so that a gap between the fixed scroll wrap and the orbiting scroll wrap becomes maximum.

[0013] As a result, when the control unit performs reverse rotation startup, the gap between the fixed scroll and the orbiting scroll is maximized. Therefore, during forward rotation startup, the gap between the fixed scroll and the orbiting scroll is maintained at its maximum. During liquid discharge startup, the orbiting scroll orbits while maintaining the gap between the fixed scroll and the orbiting scroll at its maximum. This further reduces liquid compression in the compression mechanism, allowing liquid refrigerant to be discharged from the compression mechanism while further minimizing the loads applied to the fixed scroll and the orbiting scroll.

[0014] In the above-mentioned scroll compressor, it is preferred that, during the starting operation, after the control unit drives the motor at the predetermined rotation speed, it executes a forward start after the liquid of the swung sleeve is discharged in a manner such that the fixed scroll wall and the orbiting scroll wall are in contact with each other.

[0015] Thus, the control unit executes forward rotation startup after liquid discharge, and the bushing swings in a manner that brings the fixed scroll wall and the orbiting scroll wall into contact with each other. Therefore, preparations for switching from startup operation to normal operation and efficiently compressing the refrigerant using the compression mechanism during normal operation can be smoothly carried out.

[0016] In the above-mentioned scroll compressor, it is preferred that, during the starting operation, after executing the forward rotation start after the liquid discharge, the control unit reduces the rotational acceleration of the motor compared to when the forward rotation start after the liquid discharge is executed, and rotates the motor forward, thereby gradually approaching the commanded speed in the normal operation.

[0017] Thus, during startup operation, after executing the forward start after liquid discharge, the control unit reduces the motor's rotational acceleration compared to the forward start after liquid discharge, and then rotates the motor forward. This causes the motor's rotational speed to gradually approach the commanded rotational speed during normal operation. Therefore, when the control unit switches from startup operation to normal operation and executes normal operation, the motor can be driven with high precision at the commanded rotational speed during normal operation.

[0018] Effects of the Invention

[0019] According to the present invention, liquid refrigerant can be efficiently discharged from the compression mechanism while suppressing the loads applied to the fixed scroll wrap and the orbiting scroll wrap. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of a scroll compressor in the embodiment.

[0021] Figure 2 It is a front view showing the bushing and the eccentric shaft.

[0022] Figure 3 It is a cross-sectional view showing a fixed scroll and an orbiting scroll.

[0023] Figure 4 It is a cross-sectional view showing a fixed scroll and an orbiting scroll.

[0024] Figure 5 It is a graph showing the fluctuation of the rotation speed of the motor.

[0025] Description of Reference Numerals

[0026] 10…Scroll compressor, 11…Casing, 15…Rotating shaft, 22…Motor, 25…Fixed scroll, 25a…Fixed base plate, 25b…Fixed scroll wall, 26…Orbiting scroll, 26a…Orbiting base plate, 26b…Orbiting scroll wall, 50…Eccentric shaft, 51…Bushing, 60…Control unit, C1…Compression mechanism. DETAILED DESCRIPTION

[0027] Below, according to Figures 1 to 5 An embodiment of a scroll compressor will be described. The scroll compressor of this embodiment is used in, for example, a vehicle air conditioner.

[0028] <Overview of Scroll Compressors>

[0029] like Figure 1 As shown, the scroll compressor 10 includes a cylindrical housing 11. The housing 11 includes a motor housing 12, a shaft support housing 13, and a discharge housing 14. The motor housing 12, the shaft support housing 13, and the discharge housing 14 are made of metal. For example, the motor housing 12, the shaft support housing 13, and the discharge housing 14 are made of aluminum. The scroll compressor 10 also includes a rotating shaft 15. The rotating shaft 15 is housed within the housing 11.

[0030] The motor housing 12 has a plate-shaped end wall 12a and a cylindrical peripheral wall 12b. The peripheral wall 12b extends cylindrically from the outer periphery of the end wall 12a. The axial direction of the peripheral wall 12b is consistent with the axial direction of the rotating shaft 15. The motor housing 12 has a plurality of internal threaded holes 12c. Each internal threaded hole 12c is formed at the open end of the peripheral wall 12b. In addition, Figure 1 For ease of illustration, only one internally threaded hole 12c is shown. Furthermore, the motor housing 12 has a suction port 12h. The suction port 12h draws in refrigerant. The suction port 12h is formed in a portion of the peripheral wall 12b located on the end wall 12a side. The suction port 12h connects the inside and outside of the motor housing 12.

[0031] The motor housing 12 has a cylindrical bearing retaining portion 12d. The bearing retaining portion 12d protrudes from the center of the inner surface of the end wall 12a. The first end portion, one axial end portion of the rotating shaft 15, is inserted into the bearing retaining portion 12d. The scroll compressor 10 includes a bearing 16. The bearing 16 is, for example, a rolling bearing. The bearing 16 is disposed between the inner circumferential surface of the bearing retaining portion 12d and the outer circumferential surface of the first end portion of the rotating shaft 15. The first end portion of the rotating shaft 15 is rotatably supported by the motor housing 12 via the bearing 16.

[0032] The shaft support housing 13 includes a plate-shaped end wall 17 and a cylindrical peripheral wall 18. The peripheral wall 18 extends cylindrically from the outer periphery of the end wall 17. The axial direction of the peripheral wall 18 coincides with the axial direction of the rotating shaft 15. Furthermore, the shaft support housing 13 includes an annular flange wall 19. The flange wall 19 extends radially outward from the end of the outer periphery of the peripheral wall 18 opposite the end wall 17 toward the rotating shaft 15.

[0033] The shaft support housing 13 has a circular insertion hole 17a. Insertion hole 17a is formed in the center of the end wall 17. Insertion hole 17a extends through the end wall 17 in the thickness direction. The rotating shaft 15 is inserted through insertion hole 17a. A top end surface 15e of the rotating shaft 15, located on the second end side of the other axial end of the rotating shaft 15, is located inside the peripheral wall 18.

[0034] The scroll compressor 10 includes a bearing 21. The bearing 21 is, for example, a rolling bearing. The bearing 21 is disposed between the inner circumferential surface of the peripheral wall 18 and the outer circumferential surface of the rotating shaft 15. Furthermore, the rotating shaft 15 is rotatably supported by the shaft support housing 13 via the bearing 21. Therefore, the shaft support housing 13 rotatably supports the rotating shaft 15. Thus, the rotating shaft 15 is rotatably supported by the housing 11 relative to the housing 11.

[0035] The shaft support housing 13 has a plurality of bolt insertion holes 19a. Each bolt insertion hole 19a is formed in the outer periphery of the flange wall 19. Each bolt insertion hole 19a penetrates the flange wall 19 in the thickness direction. Each bolt insertion hole 19a of the flange wall 19 is connected to each internal threaded hole 12c of the motor housing 12. Figure 1 In FIG. 1 , for convenience of explanation, only one bolt insertion hole 19 a is shown.

[0036] The scroll compressor 10 includes a motor chamber 20. The motor chamber 20 is defined by the motor housing 12 and the shaft support housing 13. Together, the motor housing 12 and the shaft support housing 13 define the motor chamber 20. Thus, the motor chamber 20 is formed within the housing 11. The motor chamber 20 communicates with the suction port 12h. Refrigerant is drawn into the motor chamber 20 from the suction port 12h.

[0037] The scroll compressor 10 includes a motor 22. The motor 22 is housed in a motor chamber 20. The motor 22 includes a cylindrical stator 23 and a cylindrical rotor 24. The rotor 24 is disposed inside the stator 23. The rotor 24 rotates integrally with the rotating shaft 15. The stator 23 surrounds the rotor 24. The rotor 24 includes a rotor core 24a fixed to the rotating shaft 15 and a plurality of permanent magnets (not shown) disposed on the rotor core 24a.

[0038] The stator 23 includes a cylindrical stator core 23a and a motor coil 23b. The stator core 23a is fixed to the inner peripheral surface of the peripheral wall 12b of the motor case 12. The motor coil 23b is wound around the stator core 23a.

[0039] The scroll compressor 10 includes a control unit 60. The control unit 60 controls the drive of the motor 22. The control unit 60 is an inverter device that controls the switching action of the switching element. The control unit 60 can be implemented by, for example, one or more dedicated hardware circuits and / or one or more processors (control circuits) that operate according to a computer program (software). The processor includes a CPU and memories such as RAM and ROM, and the memory stores, for example, program codes or instructions configured to enable the processor to perform various processes. The memory, i.e., the computer-readable medium, includes all available media that can be accessed using a general-purpose or dedicated computer.

[0040] The control unit 60 is electrically connected to the air conditioning ECU 61. The air conditioning ECU 61 controls the entire vehicle air conditioning system. The air conditioning ECU 61 is configured to monitor the vehicle interior temperature, set temperature, and other parameters. The air conditioning ECU 61 transmits various commands to the control unit 60, such as commands to operate and stop the motor 22. These commands from the air conditioning ECU 61 are external commands received by the control unit 60.

[0041] The control unit 60 periodically turns on / off the switching element based on the instruction from the air conditioning ECU 61. In detail, the control unit 60 performs pulse width modulation control (PWM control) on the switching element based on the instruction from the air conditioning ECU 61. More specifically, the control unit 60 uses the carrier signal and the command voltage value signal (comparison object signal) to generate a control signal. In addition, the control unit 60 converts DC power into AC power by controlling the on / off of the switching element using the generated control signal. The converted AC power is supplied to the motor coil 23b as driving power. As a result, the rotor 24 rotates, and the rotating shaft 15 rotates integrally with the rotor 24. Therefore, the motor 22 rotates the rotating shaft 15.

[0042] Here, the forward rotation state of the motor 22 refers to the forward rotation state of the rotor 24. On the other hand, the reverse rotation state of the motor 22 refers to the reverse rotation state of the rotor 24. When the motor 22 rotates forward, the rotating shaft 15 rotates in the forward direction. At this time, the direction of the current flowing from the control unit 60 to the motor coil 23b during the forward rotation of the motor 22 is defined as the first direction. Furthermore, if the direction of the current flowing from the control unit 60 to the motor coil 23b is switched to the second direction, which is opposite to the first direction, the motor 22 rotates in the reverse direction. This causes the rotating shaft 15 to rotate in the direction opposite to the forward direction.

[0043] The control unit 60 can control the rotational speed of the motor 22 by estimating the position of the rotor 24 based on the current flowing from the control unit 60 to the motor coil 23b, without using a sensor such as a resolver to detect the position (rotation angle) of the rotor 24. Therefore, the control unit 60 is configured to be able to grasp the rotational speed of the motor 22 based on the current flowing from the control unit 60 to the motor coil 23b.

[0044] The scroll compressor 10 includes a compression mechanism C1. The compression mechanism C1 includes a fixed scroll 25 and an orbiting scroll 26. The compression mechanism C1 is a scroll type. The orbiting scroll 26 orbits relative to the fixed scroll 25 as the rotating shaft 15 rotates. Furthermore, the orbiting scroll 26 compresses refrigerant together with the fixed scroll 25 as the rotating shaft 15 rotates. Thus, the compression mechanism C1 compresses the refrigerant while being driven by the motor 22.

[0045] The fixed scroll 25 includes a fixed base plate 25a and a fixed scroll wall 25b. The fixed base plate 25a is disc-shaped. A discharge port 25h is formed in the center of the fixed base plate 25a. The discharge port 25h is in the shape of a circular hole. The discharge port 25h penetrates the fixed base plate 25a in the thickness direction. The fixed scroll wall 25b rises from the fixed base plate 25a. The fixed scroll 25 also includes an outer peripheral wall 25c. The outer peripheral wall 25c rises from the outer periphery of the fixed base plate 25a. The outer peripheral wall 25c surrounds the fixed scroll wall 25b.

[0046] The scroll compressor 10 includes a valve mechanism 25v. The valve mechanism 25v is attached to a surface of the fixed base plate 25a opposite to the fixed scroll 25b. The valve mechanism 25v is configured to open and close a discharge port 25h.

[0047] The swirling scroll member 26 has a swirling base plate 26a and a swirling vortex wall 26b. The swirling base plate 26a is disc-shaped. The swirling base plate 26a is opposite to the fixed base plate 25a. The swirling vortex wall 26b rises from the swirling base plate 26a toward the fixed base plate 25a and engages with the fixed swirling wall 25b. The swirling scroll member 26 is located on the inner side of the outer peripheral wall 25c. The swirling scroll member 26 revolves on the inner side of the outer peripheral wall 25c. The top surface of the fixed swirling wall 25b is in contact with the swirling base plate 26a. The top surface of the swirling vortex wall 26b is in contact with the fixed base plate 25a.

[0048] The scroll compressor 10 includes a compression chamber 27. Compression chamber 27 is defined by a fixed base plate 25a, a fixed scroll wall 25b, an orbiting base plate 26a, and an orbiting scroll wall 26b. Thus, compression chamber 27 is defined between the fixed scroll 25 and the orbiting scroll 26. Compression chamber 27 takes in and compresses refrigerant from the outside.

[0049] The scroll compressor 10 includes a boss 28. The boss 28 protrudes cylindrically from the center of an end surface 26e of the rotating base plate 26a, which is opposite the fixed base plate 25a. The boss 28 is cylindrical, and the axial direction of the boss 28 coincides with the axial direction of the rotating shaft 15.

[0050] The rotating base plate 26a has a plurality of grooves 26d. The plurality of grooves 26d are formed around the protrusion 28 on the end surface 26e of the rotating base plate 26a. The plurality of grooves 26d are arranged at predetermined intervals in the circumferential direction of the rotating shaft 15. Figure 1 For ease of explanation, only one groove portion 26d is shown. An annular ring member 29 is fitted into each groove portion 26d. A pin 30 is inserted into each ring member 29. Each pin 30 is provided on the end surface 13e of the shaft support housing 13 on the orbiting scroll 26 side.

[0051] The scroll compressor 10 includes an annular elastic plate 31 . The elastic plate 31 is sandwiched between the end surface 13 e of the shaft support housing 13 and the open end surface of the outer peripheral wall 25 c . The elastic plate 31 constantly urges the orbiting scroll 26 toward the fixed scroll 25 .

[0052] The discharge casing 14 includes a plate-shaped end wall 14a and a cylindrical peripheral wall 14b. The peripheral wall 14b extends cylindrically from the outer periphery of the end wall 14a. The axial direction of the peripheral wall 14b coincides with the axial direction of the rotating shaft 15. The peripheral wall 14b surrounds the fixed scroll 25. Therefore, the fixed scroll 25 is housed within the casing 11.

[0053] The discharge housing 14 has a plurality of bolt insertion holes 14c. Each bolt insertion hole 14c is formed in the peripheral wall 14b. Figure 1 In the figure, only one bolt insertion hole 14 c is shown for convenience of explanation. Each bolt insertion hole 14 c communicates with each bolt insertion hole 19 a of the flange wall 19 .

[0054] Bolts B1 passing through the bolt insertion holes 14c pass through the bolt insertion holes 19a of the flange wall 19 and are screwed (threadedly engaged) into the internally threaded holes 12c of the motor housing 12. This connects the shaft support housing 13 to the peripheral wall 12b of the motor housing 12, and the discharge housing 14 to the flange wall 19 of the shaft support housing 13. Thus, the motor housing 12, the shaft support housing 13, and the discharge housing 14 are arranged in this order in the axial direction of the rotating shaft 15. The fixed scroll 25 is sandwiched between the end wall 14a of the discharge housing 14 and the shaft support housing 13. In this way, the fixed scroll 25 is fixed to the housing 11.

[0055] The scroll compressor 10 includes an intake passage 35. The intake passage 35 includes a first groove 36, a first hole 37, a second groove 38, and a second hole 39. The first groove 36 is formed in a portion of the inner circumferential surface of the peripheral wall 12b of the motor housing 12. The first groove 36 opens at the open end of the peripheral wall 12b. The first hole 37 is formed in the outer circumference of the flange wall 19 of the shaft support housing 13. The first hole 37 penetrates the flange wall 19 in the thickness direction. The first hole 37 communicates with the first groove 36. The second groove 38 is formed in a portion of the inner circumferential surface of the peripheral wall 14b of the discharge housing 14. The second groove 38 communicates with the first hole 37. The second hole 39 is formed in the outer circumferential wall 25c of the fixed scroll 25. The second hole 39 penetrates the outer circumferential wall 25c in the thickness direction. The second hole 39 communicates with the second groove 38. The second hole 39 communicates with the outermost portion of the compression chamber 27.

[0056] The refrigerant in the motor chamber 20 is drawn into the compression chamber 27 through the first groove 36, the first hole 37, the second groove 38, and the second hole 39. The refrigerant drawn into the compression chamber 27 is compressed within the compression chamber 27 by the orbital motion of the orbiting scroll 26. In this manner, the compression mechanism C1 compresses the refrigerant drawn into the casing 11.

[0057] The scroll compressor 10 includes a discharge chamber 40. The discharge chamber 40 is defined between the fixed base plate 25a and the end wall 14a of the discharge housing 14. The discharge chamber 40 communicates with the discharge port 25h. Refrigerant compressed in the compression chamber 27 is discharged into the discharge chamber 40. The discharge housing 14 includes a discharge port 41. The discharge port 41 is formed in the end wall 14a of the discharge housing 14. The discharge port 41 discharges the refrigerant discharged into the discharge chamber 40 to the exterior of the housing 11.

[0058] The scroll compressor 10 includes an eccentric shaft 50. The eccentric shaft 50 protrudes from the top end surface 15e of the rotating shaft 15 and extends parallel to the axis L1 of the rotating shaft 15 at a position eccentric to the axis L1 of the rotating shaft 15. Therefore, the eccentric shaft 50 is provided on the rotating shaft 15. The eccentric shaft 50 is integrally formed with the rotating shaft 15. The axial direction of the eccentric shaft 50 extends in the same direction as the axial direction of the rotating shaft 15. The eccentric shaft 50 protrudes from the top end surface 15e of the rotating shaft 15 toward the orbiting scroll 26. The eccentric shaft 50 is inserted into the boss 28.

[0059] The scroll compressor 10 includes a bushing 51. The bushing 51 is cylindrical. Inside the bushing 51 is a through-hole 51a. Therefore, the bushing 51 has the through-hole 51a. The eccentric shaft 50 is inserted into the through-hole 51a. Therefore, the bushing 51 is inserted into the eccentric shaft 50. The bushing 51 is positioned inside the boss 28. Therefore, the bushing 51 is positioned inside the boss 28.

[0060] like Figure 2 As shown, the through-hole 51a is formed in the bushing 51 such that the center L3 of the through-hole 51a is located eccentrically relative to the center L2 of the bushing 51. Therefore, the wall thickness of the bushing 51 is thinner at a portion closer to the center L3 of the through-hole 51a than to the center L2 of the bushing 51 than to the center L3 of the bushing 51. The center L3 of the through-hole 51a is also the center of the eccentric shaft 50. Furthermore, the bushing 51 can swing about the eccentric shaft 50.

[0061] like Figure 1 As shown, the scroll compressor 10 includes a balancing weight 52. The balancing weight 52 is integrated with the bushing 51. The balancing weight 52 is integrally formed with the bushing 51. The balancing weight 52 protrudes outward from a portion of the outer peripheral surface of the bushing 51. The balancing weight 52 is housed within the peripheral wall 18 of the shaft support housing 13.

[0062] The scroll compressor 10 includes a bearing 53. The bearing 53 is a cylindrical sliding bearing. The bearing 53 is disposed inside the boss 28. Furthermore, the bearing 53 is disposed between the inner circumferential surface of the boss 28 and the outer circumferential surface of the bushing 51. The bushing 51 is rotatably supported by the boss 28 via the bearing 53.

[0063] The rotation of the rotating shaft 15 is transmitted to the orbiting scroll 26 via the eccentric shaft 50, the bushing 51, and the bearing 53. As a result, the orbiting scroll 26 rotates. Furthermore, the contact between the inner circumferential surfaces of the pins 30 and the ring members 29 prevents the orbiting scroll 26 from rotating and only allows the orbiting scroll 26 to revolve. As a result, the orbiting scroll 26 revolves while the orbiting scroll wall 26b is in contact with the fixed scroll wall 25b. Furthermore, as the orbiting scroll 26 revolves, the volume of the compression chamber 27 decreases, thereby compressing the refrigerant in the compression chamber 27. The orbiting scroll 26 revolves inside the outer circumferential wall 25c as the rotating shaft 15 rotates. The balancing weight 52 offsets the centrifugal force acting on the orbiting scroll 26 when the orbiting scroll 26 revolves. As a result, the imbalance of the orbiting scroll 26 is reduced.

[0064] <Driven Crank Mechanism>

[0065] The center L2 of the bushing 51 is located radially outward of the axis L1 of the rotating shaft 15. The center of the orbiting base plate 26a coincides with the center L2 of the bushing 51. Furthermore, the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 is the orbital radius of the orbiting scroll 26.

[0066] As the bushing 51 oscillates about the eccentric shaft 50, the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 changes, thereby making the orbital radius of the orbiting scroll 26 variable. Therefore, in the scroll compressor 10, the orbital radius of the orbiting scroll 26 is variable according to the oscillation of the bushing 51 about the eccentric shaft 50. Thus, the eccentric shaft 50, bushing 51, and bearing 53 constitute a so-called driven crank mechanism 54 that makes the orbital radius of the orbiting scroll 26 variable. Such driven crank mechanisms 54 are already known.

[0067] Since minute processing errors and assembly errors may occur in the fixed scroll 25 and the orbiting scroll 26 , a play (gap) is provided in advance between the fixed scroll wall 25 b and the orbiting scroll wall 26 b .

[0068] When the motor 22 rotates forward and the rotating shaft 15 rotates in the forward direction, the bushing 51 oscillates about the eccentric shaft 50 due to the compressive load acting on the orbiting scroll 26. When the bushing 51 oscillates about the eccentric shaft 50, the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 increases, thereby increasing the orbital radius of the orbiting scroll 26.

[0069] like Figure 3 As shown, if the orbiting radius of the orbiting scroll 26 increases, the orbiting scroll 26b contacts the fixed scroll 25b, restricting the bushing 51 from swinging about the eccentric shaft 50. As a result, the orbiting radius of the orbiting scroll 26 is fixed.

[0070] Furthermore, since the rotation of the rotating shaft 15 is transmitted to the orbiting scroll 26 via the eccentric shaft 50, the bushing 51, and the bearing 53, the orbiting scroll 26 rotates in the positive direction. Then, at the point in time when the orbiting scroll wall 26b contacts the fixed scroll wall 25b, the pin 30 and the ring member 29 come into contact. This prevents the orbiting scroll 26 from rotating, and only allows the orbiting scroll 26 to revolve in the positive direction. Thus, the orbiting scroll 26 revolves in the positive direction while the orbiting scroll wall 26b contacts the fixed scroll wall 25b. This suppresses the leakage of refrigerant from the compression chamber 27, and the volume of the compression chamber 27 is reduced, thereby compressing the refrigerant.

[0071] When assembling the orbiting scroll 26 to the fixed scroll 25, the bushing 51 is swung about the eccentric shaft 50 in a direction opposite to the direction in which the rotating shaft 15 rotates in the forward direction. This causes the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 to decrease, reducing the orbital radius of the orbiting scroll 26.

[0072] like Figure 4 As shown, if the orbiting radius of the orbiting scroll 26 is reduced, the relative position of the orbiting scroll wall 26b with respect to the fixed scroll wall 25b becomes a position where the orbiting scroll wall 26b does not contact the fixed scroll wall 25b. As a result, the orbiting scroll 26 can be easily assembled with respect to the fixed scroll 25. Figure 4 , a state is shown in which the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b is maximized.

[0073] Furthermore, when the bushing 51 oscillates about the eccentric shaft 50 in a direction opposite to that when the rotating shaft 15 rotates in the forward direction, the bushing 51 is restricted from oscillating until the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 increases. When the bushing 51 oscillates about the eccentric shaft 50 in a direction opposite to that when the rotating shaft 15 rotates in the forward direction, the bushing 51 is restricted from oscillating when the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 becomes the shortest.

[0074] <Normal Operation>

[0075] Figure 5 The change of the rotation speed of the motor 22 is shown. Figure 5 As shown, a program for executing normal operation of the drive motor 22 is pre-stored in the control unit 60. Therefore, the control unit 60 executes normal operation of the drive motor 22. In normal operation, the control unit 60 drives the motor 22 using sensorless control. In sensorless control, the control unit 60 estimates the position of the rotor 24 based on the current flowing to the motor 22 and the input voltage. Furthermore, based on the estimated position of the rotor 24, the control unit 60 converts the current flowing to the motor 22 into an excitation component current, i.e., a d-axis current, and a torque component current, i.e., a q-axis current. The control unit 60 controls the on-off of the switching element in such a manner that the d-axis current and the q-axis current become target values. Thus, in normal operation, the motor 22 rotates at the command speed N1 sent from the air conditioning ECU 61.

[0076] <Startup Operation>

[0077] The control unit 60 pre-stores a program for executing a startup operation to discharge liquid refrigerant from the compression mechanism C1 before executing normal operation. Therefore, the control unit 60 executes the startup operation to discharge liquid refrigerant from the compression mechanism C1 before executing normal operation. The control unit 60 executes the startup operation by receiving a startup command from the air conditioning ECU 61. Furthermore, the control unit 60 pre-stores a program for switching from the startup operation to normal operation when the rotational speed of the motor 22 reaches the commanded rotational speed N1.

[0078] The control unit 60 has pre-stored a program for executing a reverse start during the startup operation, which reverses the rotation of the motor 22. Therefore, during the startup operation, the control unit 60 executes a reverse start, which reverses the rotation of the motor 22. During the reverse start, the control unit 60 oscillates the bushing 51 to reduce the orbiting radius of the orbiting scroll 26 and increase the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b.

[0079] Specifically, if Figure 4As shown, during reverse start, the control unit 60 swings the bushing 51 in such a manner that the gap between the fixed vortex wall 25b and the orbiting vortex wall 26b becomes the largest. During reverse start, in order to swing the bushing 51 in such a manner that the gap between the fixed vortex wall 25b and the orbiting vortex wall 26b becomes the largest, the control unit 60 increases the rotational acceleration of the motor 22 and reverses the motor 22. In addition, "rotational acceleration of the motor 22" refers to the amount of change in the rotational speed of the motor 22 per unit time. When performing reverse start, the bushing 51 swings around the eccentric shaft 50 in such a manner that the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 is reduced. The control unit 60 pre-stores a program that first performs reverse start as a starting operation if a start command is received from the air-conditioning ECU 61.

[0080] like Figure 5 As shown, during the starting operation, the control unit 60 pre-stores a program for executing a forward start to rotate the motor 22 forward while maintaining the posture of the bushing 51 after executing the reverse start. Therefore, the control unit 60 executes a forward start to rotate the motor 22 forward while maintaining the posture of the bushing 51 after executing the reverse start. The slope of the solid line representing the change in the rotation speed of the motor 22 when executing the forward start is gentler than the slope of the solid line representing the change in the rotation speed of the motor 22 when executing the reverse start. Therefore, the change in the rotation speed of the motor 22 per unit time when executing the forward start is smaller than the change in the rotation speed of the motor 22 per unit time when executing the reverse start. In this way, during the forward start, the control unit 60 reduces the rotation acceleration of the motor 22 compared to when executing the reverse start.

[0081] The control unit 60 pre-stores a program for executing liquid discharge startup when the rotational speed of the motor 22 reaches a predetermined rotational speed Nx during forward startup. Therefore, the control unit 60 executes liquid discharge startup when the rotational speed of the motor 22 reaches the predetermined rotational speed Nx during forward startup. During liquid discharge startup, the control unit 60 drives the motor 22 at the predetermined rotational speed Nx to cause the orbiting scroll 26 to orbit, thereby discharging liquid refrigerant from the compression mechanism C1.

[0082] The control unit 60 has pre-stored a program for executing a forward rotation start after liquid discharge after driving the motor 22 at a predetermined rotation speed Nx during the startup operation. Therefore, during the startup operation, the control unit 60 executes a forward rotation start after liquid discharge after driving the motor 22 at a predetermined rotation speed Nx. In the forward rotation start after liquid discharge, as shown in FIG. Figure 3 As shown, the control unit 60 swings the bushing 51 so that the fixed scroll 25b and the orbiting scroll 26b are in contact with each other.

[0083] like Figure 5As shown, the slope of the solid line representing the change in the rotational speed of the motor 22 during forward start-up after liquid discharge is approximately the same as the slope of the solid line representing the change in the rotational speed of the motor 22 during reverse start-up. Thus, the amount of change in the rotational speed of the motor 22 per unit time during forward start-up after liquid discharge is approximately the same as the amount of change in the rotational speed of the motor 22 per unit time during reverse start-up. During forward start-up after liquid discharge, the control unit 60 drives the motor 22 at a predetermined rotational speed Nx and then swings the bushing 51 so that the fixed scroll wall 25b and the orbiting scroll wall 26b are in contact with each other, thereby increasing the rotational acceleration of the motor 22 and causing the motor 22 to rotate forward.

[0084] The direction of the bushing 51's swing during forward rotation after liquid discharge is opposite to the direction of the bushing 51's swing during reverse rotation. Specifically, during forward rotation after liquid discharge, the bushing 51 swings about the eccentric shaft 50 so that the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15 increases.

[0085] The control unit 60 pre-stores a program for executing a low-acceleration forward start during startup operation, after performing a forward start after liquid discharge, to gradually bring the rotational speed of the motor 22 closer to the commanded rotational speed N1 during normal operation. Therefore, during startup operation, after performing the forward start after liquid discharge, the control unit 60 gradually brings the rotational speed of the motor 22 closer to the commanded rotational speed N1 during normal operation. The slope of the solid line representing the change in the rotational speed of the motor 22 during the low-acceleration forward start is gentler than the slope of the solid line representing the change in the rotational speed of the motor 22 during the forward start after liquid discharge. Consequently, the change in the rotational speed of the motor 22 per unit time during the low-acceleration forward start is smaller than the change in the rotational speed of the motor 22 per unit time during the forward start after liquid discharge. Thus, during the low-acceleration forward start, the control unit 60 reduces the rotational acceleration of the motor 22 compared to the forward start after liquid discharge, and causes the motor 22 to rotate forward.

[0086] [Effects of Implementation Methods]

[0087] Next, the effects of the embodiment will be described.

[0088] In the scroll compressor 10, the refrigerant is sometimes cooled and liquefied when the scroll compressor 10 stops. Therefore, the control unit 60 performs a startup operation to discharge the liquid refrigerant from the compression mechanism C1 before performing normal operation using sensorless control to drive the motor 22. In the startup operation, the control unit 60 first performs a reverse start. If the reverse start is performed, the motor 22 reverses, and thereby the bushing 51 swings in a manner that reduces the orbital radius of the orbiting scroll 26 and increases the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b. In this way, before performing normal operation, the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b is large.

[0089] Next, the control unit 60 performs a forward start after executing a reverse start. During the forward start, the rotational acceleration of the motor 22 is reduced compared to the reverse start. This maintains the position of the bushing 51 even when the motor 22 is accelerated in the forward direction. Therefore, even when the motor 22 is accelerated in the forward direction, the gap between the fixed scroll 25b and the orbiting scroll 26b remains large.

[0090] Then, when the motor 22 reaches a predetermined speed Nx during forward rotation, the control unit 60 drives the motor 22 at the predetermined speed Nx to cause the orbiting scroll 26 to orbit, thereby discharging liquid refrigerant from the compression mechanism C1. This causes the orbiting scroll 26 to orbit while maintaining a large gap between the fixed scroll 25b and the orbiting scroll 26b, making liquid compression less likely to occur in the compression mechanism C1.

[0091] Next, after driving the motor 22 at a predetermined rotation speed Nx, the control unit 60 performs a forward rotation start after liquid discharge. As a result, the fixed scroll wall 25b and the orbiting scroll wall 26b are in contact with each other. Moreover, after performing the forward rotation start after liquid discharge, the control unit 60 performs a low-acceleration forward rotation start. As a result, the rotation speed of the motor 22 gradually approaches the commanded rotation speed N1 during normal operation. Then, if the rotation speed of the motor 22 reaches the commanded rotation speed N1, the control unit 60 switches from the starting operation to the normal operation. As a result, the scroll compressor 10 uses the compression mechanism C1 to compress the refrigerant during normal operation.

[0092] [Effects of the embodiment]

[0093] In the embodiment, the following effects can be obtained.

[0094] (1) The control unit 60 performs a start-up operation to discharge liquid refrigerant from the compression mechanism C1 before performing normal operation of the drive motor 22. During the start-up operation, the control unit 60 first performs a reverse start. If the reverse start is performed, the motor 22 reverses, thereby causing the bushing 51 to swing in a manner that reduces the orbital radius of the orbiting scroll 26 and increases the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b. In this way, before performing normal operation, the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b is large. Then, after performing the reverse start, the control unit 60 performs a forward start. In the forward start, the rotational acceleration of the motor 22 is reduced compared to when the reverse start is performed, thereby maintaining the posture of the bushing 51 even if the motor 22 is accelerated in a forward manner. Therefore, even if the motor 22 is accelerated in a forward manner, the gap between the fixed scroll wall 25b and the orbiting scroll wall 26b is maintained in a large state. Then, when the motor 22 reaches a predetermined speed Nx during forward start-up, the control unit 60 executes a liquid discharge start-up, driving the motor 22 at the predetermined speed Nx to cause the orbiting scroll 26 to orbit, thereby discharging liquid refrigerant from the compression mechanism C1. This causes the orbiting scroll 26 to orbit while maintaining a large gap between the fixed scroll 25b and the orbiting scroll 26b, thus minimizing liquid compression in the compression mechanism C1. As a result, liquid refrigerant can be efficiently discharged from the compression mechanism C1 while minimizing the loads applied to the fixed scroll 25b and the orbiting scroll 26b.

[0095] (2) Reverse rotation startup is performed by the control unit 60, and the gap between the fixed scroll 25b and the orbiting scroll 26b is maximized. Therefore, during forward rotation startup, the gap between the fixed scroll 25b and the orbiting scroll 26b is maintained at its maximum. During liquid discharge startup, the orbiting scroll 26 is caused to orbit while the gap between the fixed scroll 25b and the orbiting scroll 26b is maximized. This further reduces liquid compression in the compression mechanism C1, allowing liquid refrigerant to be discharged from the compression mechanism C1 while further reducing the loads applied to the fixed scroll 25b and the orbiting scroll 26b.

[0096] (3) The control unit 60 performs forward rotation startup after liquid discharge, and the bushing 51 swings so that the fixed scroll 25b and the orbiting scroll 26b are in contact with each other. Therefore, preparations for switching from startup operation to normal operation and efficiently compressing the refrigerant using the compression mechanism C1 during normal operation can be smoothly performed.

[0097] (4) During the startup operation, after executing the forward rotation start after liquid discharge, the control unit 60 reduces the rotational acceleration of the motor 22 compared to the forward rotation start after liquid discharge, and rotates the motor 22 forward. As a result, the rotational speed of the motor 22 gradually approaches the commanded rotational speed N1 during normal operation. Therefore, when the startup operation is switched to normal operation, the control unit 60 can drive the motor 22 with high precision at the commanded rotational speed N1 during normal operation.

[0098] (5) According to this embodiment, for example, when the scroll compressor 10 is started, there is no need to perform operations such as extremely reducing the rotational speed of the motor 22 to discharge liquid refrigerant from the compression mechanism C1 in order to suppress the loads applied to the fixed scroll wrap 25b and the orbiting scroll wrap 26b. Therefore, the startup responsiveness of the scroll compressor 10 can be improved.

[0099] [Change Example]

[0100] Furthermore, the above-described embodiment can be modified and implemented as follows: The above-described embodiment and the following modified examples can be combined and implemented within a range that does not technically contradict each other.

[0101] In the embodiment, the gap between the fixed scroll 25b and the orbiting scroll 26b does not need to be maximized during reverse start-up. In short, during reverse start-up, the bushing 51 is swung and the motor 22 is reversed in such a manner that the orbiting radius of the orbiting scroll 26 is reduced and the gap between the fixed scroll 25b and the orbiting scroll 26b is increased.

[0102] In the embodiment, during the startup operation, the control unit 60 may not execute the low acceleration forward start, but may switch to normal operation after executing the post-liquid discharge forward start and then switching the rotation speed of the motor 22 to the command rotation speed N1.

[0103] In the embodiment, during normal operation, the control unit 60 drives the motor 22 using sensorless control. However, the present invention is not limited thereto. The control unit 60 may estimate the position of the rotor 24 using a sensor such as a resolver and drive the motor 22 .

[0104] In the embodiment, the eccentric shaft 50 may not be integrally formed with the rotating shaft 15 but may be a separate body from the rotating shaft 15 . In this case, the eccentric shaft 50 is attached to the distal end surface 15 e of the rotating shaft 15 .

[0105] In the embodiment, the balance weight 52 may be a separate body from the bushing 51 .

[0106] In the embodiment, the scroll compressor 10 is used in a vehicle air conditioner, but the invention is not limited thereto. In short, the scroll compressor 10 only needs to compress the refrigerant, and the application of the scroll compressor 10 can be changed as appropriate.

[0107] In the embodiment, the object to be compressed by the scroll compressor 10 is not limited to the refrigerant, and may be, for example, a fluid such as air.

Claims

1. A scroll compressor comprising: case; a rotating shaft supported by the housing in a manner rotatable relative to the housing; a motor to rotate the rotating shaft; a control unit that controls driving of the motor; and a compression mechanism, driven by the motor and compressing the refrigerant, The compression mechanism comprises: a fixed scroll having a disc-shaped fixed base plate and a fixed scroll wall rising from the fixed base plate; and The orbiting scroll comprises a disc-shaped orbiting base plate facing the fixed base plate and an orbiting scroll wall rising from the orbiting base plate toward the fixed base plate and meshing with the fixed scroll wall, and compresses the refrigerant together with the fixed scroll member through the rotation of the rotating shaft. The rotating shaft is provided with an eccentric shaft extending parallel to the axis of the rotating shaft at a position eccentric to the axis of the rotating shaft. A bushing capable of swinging around the eccentric shaft is inserted into the eccentric shaft. The orbiting radius of the orbiting scroll is variable according to the swinging of the bushing around the eccentric shaft. The scroll compressor is characterized in that: The control unit performs a startup operation for discharging liquid refrigerant from the compression mechanism before performing a normal operation for driving the motor at a command speed. During the starting operation, a reverse start is performed to swing the bushing and reverse the motor in a manner that reduces the orbital radius of the orbiting scroll and increases the gap between the fixed vortex wall and the orbiting vortex wall. After the reverse start is performed, a forward start is performed to reduce the rotational acceleration of the motor compared to when the reverse start is performed and to rotate the motor forward while maintaining the posture of the bushing. When the forward start is performed and the rotation speed of the motor reaches a predetermined rotation speed, a liquid discharge start is performed to drive the motor at the predetermined rotation speed in a manner that discharges the liquid refrigerant from the compression mechanism to perform the orbital motion of the orbiting scroll.

2. The scroll compressor according to claim 1, wherein: During the reverse rotation start, the control unit swings the bushing so that the gap between the fixed scroll wall and the orbiting scroll wall becomes maximum.

3. The scroll compressor according to claim 1 or 2, characterized in that: In the startup operation, the control unit drives the motor at the predetermined rotation speed and then performs a liquid discharge and normal rotation startup to swing the bushing so that the fixed scroll and the orbiting scroll come into contact with each other.

4. The scroll compressor according to claim 3, wherein: In the startup operation, after executing the post-liquid discharge forward rotation startup, the control unit reduces the rotational acceleration of the motor compared to when executing the post-liquid discharge forward rotation startup and rotates the motor forward, thereby gradually approaching the motor rotation speed to the command rotation speed in the normal operation.

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