Scroll type compressor

Abstract

To efficiently discharge a liquid refrigerant from a compression mechanism while suppressing a load applied to a fixed spiral wall and a turning spiral wall respectively.SOLUTION: A control part 60 executes a start operation before executing a normal operation for driving a motor 22. In the start operation, a bush 51 is caused to swing so that a gap between a fixed spiral wall 25b and a turning spiral wall 26b becomes large by reducing a revolution radius of a turning scroll 26 and a reverse rotation start is executed for reversely rotating the motor 22. After executing the reverse rotation start, the rotational acceleration of the motor 22 is made smaller than when executing the reverse rotation start, and normal rotation start is executed for rotating the motor 22 normally and maintaining the posture of the bush 51. When the normal rotation start is executed and the rotation speed of the motor 22 reaches a predetermined rotation speed, the motor 22 is driven at the predetermined rotation speed so as to discharge a liquid refrigerant from a compression mechanism C1, and liquid discharge start is executed for performing revolving motion of the turning scroll 26.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] The scroll compressor includes a housing, a rotating shaft, a motor, and a compression mechanism. The rotating shaft is rotatably supported relative to the housing. The motor rotates the rotating shaft. The compression mechanism is driven by the motor. The compression mechanism compresses a refrigerant. The compression mechanism includes a fixed scroll and an orbiting scroll. The fixed scroll has a disk-shaped fixed base plate and a fixed spiral wall. The fixed spiral wall stands upright from the fixed base plate. The orbiting scroll has a disk-shaped orbiting base plate and an orbiting spiral wall. The orbiting base plate faces the fixed base plate. The orbiting spiral wall stands upright from the orbiting base plate toward the fixed base plate. The orbiting spiral wall meshes with the fixed spiral wall. The orbiting scroll compresses the refrigerant together with the fixed scroll as the rotating shaft rotates.

[0003] Also, as in Patent Document 1, for example, an eccentric shaft is provided on the rotating shaft. The eccentric shaft extends parallel to the rotating shaft at a position eccentric to the axis of the rotating shaft. A bushing is inserted into the eccentric shaft. The bushing can swing around the eccentric shaft. The swing of the bushing around the eccentric shaft changes the orbital radius of the orbiting scroll. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-159052 Summary of the Invention [Problem to be solved by the invention]

[0005] In such scroll compressors, the refrigerant may be cooled and liquefied when the scroll compressor is stopped. If the scroll compressor is started while liquid refrigerant resulting from liquefaction is present, liquid compression occurs in the compression mechanism when the liquid refrigerant is discharged from the compression mechanism. When liquid compression occurs in the compression mechanism, loads are applied to the fixed and orbiting scroll walls, which may cause problems such as deformation of the fixed and orbiting scroll walls. Therefore, it is desirable to efficiently discharge the liquid refrigerant from the compression mechanism while minimizing the loads applied to the fixed and orbiting scroll walls when the scroll compressor is started. [Means for solving the problem]

[0006] A scroll compressor that solves the above problem includes a housing, a rotating shaft rotatably supported relative to the housing, a motor that rotates the rotating shaft, a control unit that controls driving of the motor, and a compression mechanism that is driven by the motor and compresses a refrigerant, wherein the compression mechanism includes a fixed scroll having a disk-shaped fixed base plate and a fixed spiral wall that stands up from the fixed base plate, and an orbiting scroll that has a disk-shaped orbiting base plate facing the fixed base plate and an orbiting spiral wall that stands up from the orbiting base plate toward the fixed base plate and engages with the fixed spiral wall, and compresses the refrigerant together with the fixed scroll by rotation of the rotating shaft, and the rotating shaft is provided with an eccentric shaft that extends parallel to the rotating shaft at a position eccentric to the axis of the rotating shaft, and a bush that is inserted into the eccentric shaft and is swingable around the eccentric shaft, and a rotation of the bush is controlled by a rotation of the eccentric shaft. and a control unit for controlling the motor to rotate in a forward direction, the control unit ...

[0007] According to this configuration, the control unit performs a startup operation to discharge liquid refrigerant from the compression mechanism before performing normal operation to drive the motor. In the startup operation, the control unit first performs reverse rotation startup. When reverse rotation startup is performed, the motor rotates in reverse, thereby reducing the orbital radius of the orbiting scroll and swinging the bushing to increase the gap between the fixed scroll wall and the orbiting scroll wall. Thus, before normal operation is performed, the gap between the fixed scroll wall and the orbiting scroll wall is increased. Next, after performing reverse rotation startup, the control unit performs forward rotation startup. In forward rotation startup, the rotational acceleration of the motor is reduced compared to when reverse rotation startup is performed, thereby maintaining the bushing's position even when the motor is accelerated in the forward direction. Therefore, even when the motor is accelerated in the forward direction, the gap between the fixed scroll wall and the orbiting scroll wall remains increased. Then, when the control unit performs forward rotation startup and the motor speed reaches a predetermined speed, the control unit performs liquid discharge startup, driving the motor at a predetermined speed to cause the orbiting scroll to revolve so as to discharge liquid refrigerant from the compression mechanism. In this configuration, the orbiting scroll revolves with a large gap between the fixed and orbiting scroll walls, making it difficult for liquid compression to occur in the compression mechanism, and as a result, the liquid refrigerant can be efficiently discharged from the compression mechanism while suppressing the loads applied to the fixed and orbiting scroll walls.

[0008] In the scroll compressor, the control unit may swing the bushing so that a gap between the fixed volute wall and the orbiting volute wall becomes a maximum when the reverse rotation is started.

[0009] According to this, when the control unit executes reverse rotation start, the gap between the fixed spiral wall and the orbiting spiral wall is maximized. Therefore, when forward rotation start is executed, the gap between the fixed spiral wall and the orbiting spiral wall is maintained at its maximum, and when liquid discharge start is executed, the orbiting scroll revolves with the gap between the fixed spiral wall and the orbiting spiral wall at its maximum. This makes it even more difficult for liquid compression to occur in the compression mechanism, and allows liquid refrigerant to be discharged from the compression mechanism while further reducing the loads applied to the fixed spiral wall and the orbiting spiral wall.

[0010] In the scroll compressor, the control unit may, during the startup operation, drive the motor at the predetermined rotation speed, and then execute a positive rotation startup after liquid discharge, which swings the bushing so that the fixed spiral wall and the orbiting spiral wall are in contact with each other.

[0011] In this configuration, the control unit executes forward rotation start-up after liquid discharge, causing the bushing to swing so that the fixed volute wall and the orbiting volute wall come into contact with each other, thereby smoothly switching from startup operation to normal operation and preparing for efficient refrigerant compression by the compression mechanism in normal operation.

[0012] In the scroll compressor, in the startup operation, after executing the liquid-discharge-post-forward-rotation start-up, the control unit may reduce the rotational acceleration of the motor compared to when the liquid-discharge-post-forward-rotation start-up was executed, and rotate the motor in the forward direction, thereby gradually bringing the rotational speed of the motor closer to the command rotational speed in the normal operation.

[0013] According to this, in the startup operation, after the control unit executes the forward rotation startup after liquid discharge, the control unit reduces the rotation acceleration of the motor compared to when the forward rotation startup after liquid discharge is executed, and rotates the motor forward. As a result, the motor rotation speed gradually approaches the command rotation speed for normal operation, so that when the startup operation is switched to normal operation and the control unit executes normal operation, the motor can be driven with high precision at the command rotation speed for normal operation. [Effects of the Invention]

[0014] According to this invention, it is possible to efficiently discharge liquid refrigerant from the compression mechanism while suppressing the loads applied to the fixed volute wall and the orbiting volute wall. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of a scroll compressor according to an embodiment. [Figure 2]FIG. 2 is a front view showing the bushing and the eccentric shaft. [Figure 3] FIG. 3 is a cross-sectional view showing a fixed scroll and an orbiting scroll. [Figure 4] FIG. 4 is a cross-sectional view showing a fixed scroll and an orbiting scroll. [Figure 5] FIG. 5 is a graph showing the change in the rotation speed of the motor. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of a scroll compressor will now be described with reference to Figures 1 to 5. The scroll compressor of this embodiment is used in, for example, a vehicle air conditioner. <Outline of scroll compressor> As shown in FIG. 1 , the scroll compressor 10 includes a cylindrical housing 11. The housing 11 has a motor housing 12, a support housing 13, and a discharge housing 14. The motor housing 12, the support housing 13, and the discharge housing 14 are made of a metal material. The motor housing 12, the support housing 13, and the discharge housing 14 are made of aluminum, for example. The scroll compressor 10 also includes a rotating shaft 15. The rotating shaft 15 is accommodated in the housing 11.

[0017] 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 coincides with the axial direction of the rotary shaft 15. The motor housing 12 has a plurality of female threaded holes 12c. Each female threaded hole 12c is formed at an open end of the peripheral wall 12b. Note that for convenience of explanation, only one female threaded hole 12c is shown in FIG. 1. The motor housing 12 also has an intake port 12h. The intake port 12h draws in a refrigerant. The intake port 12h is formed in a portion of the peripheral wall 12b that is located on the end wall 12a side. The intake port 12h connects the inside and outside of the motor housing 12.

[0018] The motor housing 12 has a cylindrical bearing holder 12d. The bearing holder 12d protrudes from the center of the inner surface of the end wall 12a. A first end, which is one axial end of the rotating shaft 15, is inserted into the bearing holder 12d. The scroll compressor 10 is provided with a bearing 16. The bearing 16 is, for example, a rolling bearing. The bearing 16 is provided between the inner circumferential surface of the bearing holder 12d and the outer circumferential surface of the first end of the rotating shaft 15. The first end of the rotating shaft 15 is rotatably supported by the motor housing 12 via the bearing 16.

[0019] The journal housing 13 has 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 rotary shaft 15. The journal housing 13 also has an annular flange wall 19. The flange wall 19 extends radially outward from the rotary shaft 15 from an end of the outer periphery of the peripheral wall 18 opposite the end wall 17.

[0020] The support housing 13 has a circular insertion hole 17a. The insertion hole 17a is formed in the center of the end wall 17. The insertion hole 17a penetrates the end wall 17 in the thickness direction. The rotary shaft 15 is inserted through the insertion hole 17a. A tip end surface 15e located on the second end side, which is the other end in the axial direction of the rotary shaft 15, is located inside the peripheral wall 18.

[0021] The scroll compressor 10 includes a bearing 21. The bearing 21 is, for example, a rolling bearing. The bearing 21 is provided between the inner circumferential surface of the peripheral wall 18 and the outer circumferential surface of the rotating shaft 15. The rotating shaft 15 is rotatably supported by the support housing 13 via the bearing 21. Therefore, the support housing 13 rotatably supports the rotating shaft 15. In this manner, the rotating shaft 15 is rotatably supported with respect to the housing 11.

[0022] The support housing 13 has a plurality of bolt insertion holes 19a. Each bolt insertion hole 19a is formed on 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 in the flange wall 19 communicates with each of the female threaded holes 12c in the motor housing 12. For ease of explanation, only one bolt insertion hole 19a is shown in FIG. 1.

[0023] The scroll compressor 10 has a motor chamber 20. The motor chamber 20 is defined by a motor housing 12 and a support housing 13. The motor housing 12 defines the motor chamber 20 together with the support housing 13. In this manner, the motor chamber 20 is formed within the housing 11. The motor chamber 20 communicates with an intake port 12h. Refrigerant is drawn into the motor chamber 20 from the intake port 12h.

[0024] The scroll compressor 10 includes a motor 22. The motor 22 is housed in the 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 rotary shaft 15. The stator 23 surrounds the rotor 24. The rotor 24 includes a rotor core 24a fixed to the rotary shaft 15 and a plurality of permanent magnets (not shown) provided in the rotor core 24a.

[0025] The stator 23 has a cylindrical stator core 23a and a motor coil 23b. The stator core 23a is fixed to the inner circumferential surface of the peripheral wall 12b of the motor housing 12. The motor coil 23b is wound around the stator core 23a.

[0026] The scroll compressor 10 includes a control unit 60. The control unit 60 controls the driving of the motor 22. The control unit 60 is an inverter device that controls the switching operation of the switching elements. The control unit 60 can be realized, for example, by 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 memory such as RAM and ROM, and the memory stores, for example, program code or instructions configured to cause the processor to execute various processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0027] 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 be able to grasp the vehicle interior temperature, the set temperature, etc. The air conditioning ECU 61 transmits various commands to the control unit 60, such as a command to operate the motor 22 or a command to stop the motor 22. These various commands from the air conditioning ECU 61 are commands that the control unit 60 receives from the outside.

[0028] The control unit 60 periodically turns on / off the switching elements based on commands from the air conditioning ECU 61. Specifically, the control unit 60 performs pulse width modulation control (PWM control) on the switching elements based on commands from the air conditioning ECU 61. More specifically, the control unit 60 generates a control signal using a carrier signal (carrier wave signal) and a command voltage value signal (comparison signal). The control unit 60 then uses the generated control signal to perform on / off control of the switching elements, thereby converting DC power to AC power. The converted AC power is supplied to the motor coil 23b as drive power. This causes the rotor 24 to rotate, and the rotating shaft 15 to rotate integrally with the rotor 24. Therefore, the motor 22 rotates the rotating shaft 15.

[0029] Here, the state in which the motor 22 is rotating in the forward direction refers to the state in which the rotor 24 is rotating in the forward direction. On the other hand, the state in which the motor 22 is rotating in the reverse direction refers to the state in which the rotor 24 is rotating in the reverse direction. When the motor 22 rotates in the forward direction, 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 when the motor 22 is rotating in the forward direction is defined as a first direction. Then, when the direction of the current flowing from the control unit 60 to the motor coil 23b is switched to a second direction, which is the opposite direction to the first direction, the motor 22 rotates in the reverse direction. As a result, the rotating shaft 15 rotates in the direction opposite to the forward direction.

[0030] The control unit 60 is able to control the rotation 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 that detects the position (rotation angle) of the rotor 24. Therefore, the control unit 60 is configured to be able to grasp the rotation speed of the motor 22 based on the current flowing from the control unit 60 to the motor coil 23b.

[0031] 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 of a scroll type. The orbiting scroll 26 revolves around the fixed scroll 25 as the rotary shaft 15 rotates. The orbiting scroll 26 compresses the refrigerant together with the fixed scroll 25 as the rotary shaft 15 rotates. Therefore, the compression mechanism C1 is driven by the motor 22 and compresses the refrigerant.

[0032] The fixed scroll 25 has a fixed base plate 25a and a fixed spiral wall 25b. The fixed base plate 25a is disk-shaped. A discharge port 25h is formed in the center of the fixed base plate 25a. The discharge port 25h is a circular hole. The discharge port 25h penetrates the fixed base plate 25a in the thickness direction. The fixed spiral wall 25b stands upright from the fixed base plate 25a. The fixed scroll 25 also has an outer circumferential wall 25c. The outer circumferential wall 25c stands upright from the outer periphery of the fixed base plate 25a. The outer circumferential wall 25c surrounds the fixed spiral wall 25b.

[0033] The scroll compressor 10 includes a valve mechanism 25v. The valve mechanism 25v is attached to the surface of the fixed base plate 25a opposite to the fixed spiral wall 25b. The valve mechanism 25v is configured to be able to open and close a discharge port 25h.

[0034] The orbiting scroll 26 has an orbiting base plate 26a and an orbiting spiral wall 26b. The orbiting base plate 26a is disk-shaped. The orbiting base plate 26a faces the fixed base plate 25a. The orbiting spiral wall 26b rises from the orbiting base plate 26a toward the fixed base plate 25a and meshes with the fixed spiral wall 25b. The orbiting scroll 26 is located inside the outer peripheral wall 25c. The orbiting scroll 26 revolves inside the outer peripheral wall 25c. The tip surface of the fixed spiral wall 25b contacts the orbiting base plate 26a. The tip surface of the orbiting spiral wall 26b contacts the fixed base plate 25a.

[0035] The scroll compressor 10 includes a compression chamber 27. The compression chamber 27 is defined by a fixed base plate 25a, a fixed spiral wall 25b, an orbiting base plate 26a, and an orbiting spiral wall 26b. Therefore, the compression chamber 27 is defined between the fixed scroll 25 and the orbiting scroll 26. The compression chamber 27 takes in and compresses a refrigerant from the outside.

[0036] The scroll compressor 10 includes a boss portion 28. The boss portion 28 protrudes in a cylindrical shape from the center of an end face 26e of the rotating base plate 26a opposite the fixed base plate 25a. The boss portion 28 is cylindrical. The axial direction of the boss portion 28 coincides with the axial direction of the rotating shaft 15.

[0037] The orbiting base plate 26a has a plurality of grooves 26d. The grooves 26d are formed around the boss portions 28 on the end face 26e of the orbiting base plate 26a. The grooves 26d are arranged at predetermined intervals in the circumferential direction of the rotary shaft 15. For ease of explanation, only one groove 26d is shown in FIG. 1. An annular ring member 29 is fitted into each groove 26d. A pin 30 is inserted into each ring member 29. Each pin 30 protrudes from the end face 13e of the support housing 13 on the orbiting scroll 26 side.

[0038] The scroll compressor 10 includes an elastic plate 31. The elastic plate 31 is annular. The elastic plate 31 is sandwiched between the end face 13e of the support housing 13 and the open end face of the outer peripheral wall 25c. The elastic plate 31 constantly biases the orbiting scroll 26 toward the fixed scroll 25.

[0039] The discharge housing 14 has 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 rotary shaft 15. The peripheral wall 14b surrounds the fixed scroll 25. Therefore, the fixed scroll 25 is accommodated within the housing 11.

[0040] The discharge housing 14 has a plurality of bolt insertion holes 14c. Each bolt insertion hole 14c is formed in the peripheral wall 14b. For ease of explanation, only one bolt insertion hole 14c is shown in FIG. 1. Each bolt insertion hole 14c communicates with a corresponding bolt insertion hole 19a in the flange wall 19.

[0041] Bolts B1 passing through each bolt insertion hole 14c pass through each bolt insertion hole 19a in the flange wall 19 and are threaded into each female threaded hole 12c of the motor housing 12. As a result, the journal housing 13 is connected to the peripheral wall 12b of the motor housing 12, and the discharge housing 14 is connected to the flange wall 19 of the journal housing 13. Therefore, the motor housing 12, journal housing 13, and discharge housing 14 are arranged side by side 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 journal housing 13. In this manner, the fixed scroll 25 is fixed to the housing 11.

[0042] The scroll compressor 10 includes a suction passage 35. The suction passage 35 has 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 to an open end of the peripheral wall 12b. The first hole 37 is formed in the outer circumferential portion of the flange wall 19 of the journal 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 peripheral portion of the compression chamber 27.

[0043] The refrigerant in the motor chamber 20 passes through the first groove 36, the first hole 37, the second groove 38, and the second hole 39, and is drawn into the compression chamber 27. 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 way, the compression mechanism C1 compresses the refrigerant drawn into the housing 11.

[0044] The scroll compressor 10 has 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 is in communication with the discharge port 25h. Refrigerant compressed in the compression chamber 27 is discharged into the discharge chamber 40. The discharge housing 14 has 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 outside of the housing 11.

[0045] The scroll compressor 10 is provided with an eccentric shaft 50. The eccentric shaft 50 protrudes from the tip end surface 15e of the rotating shaft 15 and extends parallel to the rotating shaft 15 at a position eccentric with respect to the axis L1 of the rotating shaft 15. Thus, the rotating shaft 15 is provided with the eccentric shaft 50. The eccentric shaft 50 is integrally formed with the rotating shaft 15. The axial direction of the eccentric shaft 50 coincides with the axial direction of the rotating shaft 15. The eccentric shaft 50 protrudes from the tip end surface 15e of the rotating shaft 15 toward the orbiting scroll 26. The eccentric shaft 50 is inserted into the boss portion 28.

[0046] The scroll compressor 10 includes a bush 51. The bush 51 is cylindrical. The inside of the bush 51 forms a through-hole 51a. Therefore, the bush 51 has the through-hole 51a. An eccentric shaft 50 is inserted into the through-hole 51a. Therefore, the bush 51 is inserted into the eccentric shaft 50. The bush 51 is disposed inside the boss portion 28. Therefore, the bush 51 is disposed inside the boss portion 28.

[0047] 2, the through hole 51a is formed in the bushing 51 with the center L3 of the through hole 51a located at a position eccentric to the center L2 of the bushing 51. Therefore, the thickness of the bushing 51 at a portion closer to the center L3 of the through hole 51a than the center L2 of the bushing 51 is thinner than the thickness of a portion closer to the center L2 of the bushing 51 than the center L3 of the through hole 51a. The center L3 of the through hole 51a is also the center of the eccentric shaft 50. The bushing 51 can swing around the eccentric shaft 50.

[0048] As shown in FIG. 1 , the scroll compressor 10 includes a balance weight 52. The balance weight 52 is integrated with a bush 51. The balance weight 52 is formed integrally with the bush 51. The balance weight 52 protrudes outward from a portion of the outer circumferential surface of the bush 51. The balance weight 52 is housed within the peripheral wall 18 of the support housing 13.

[0049] The scroll compressor 10 includes a bearing 53. The bearing 53 is a cylindrical sliding bearing. The bearing 53 is disposed inside the boss portion 28. The bearing 53 is disposed between the inner peripheral surface of the boss portion 28 and the outer peripheral surface of the bush 51. The bush 51 is rotatably supported by the boss portion 28 via the bearing 53.

[0050] 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. This causes the orbiting scroll 26 to rotate on its axis. Contact between each pin 30 and the inner peripheral surface of each ring member 29 prevents the orbiting scroll 26 from rotating on its axis, allowing only the orbiting scroll 26 to revolve. This causes the orbiting scroll 26 to revolve while the orbiting spiral wall 26b is in contact with the fixed spiral wall 25b. As the orbiting scroll 26 revolves, the volume of the compression chamber 27 decreases, compressing the refrigerant in the compression chamber 27. As the rotating shaft 15 rotates, the orbiting scroll 26 revolves inside the outer peripheral wall 25c. The balance weight 52 offsets the centrifugal force acting on the orbiting scroll 26 as it revolves. This reduces the amount of imbalance in the orbiting scroll 26.

[0051] <Driven crank mechanism> The center L2 of the bushing 51 is located radially outward of the axis L1 of the rotary shaft 15. The center of the orbiting base plate 26a coincides with the center L2 of the bushing 51. The distance between the center L2 of the bushing 51 and the axis L1 of the rotary shaft 15 is the orbital radius of the orbiting scroll 26.

[0052] When the bushing 51 swings around the eccentric shaft 50, the distance between the center L2 of the bushing 51 and the axis L1 of the rotary shaft 15 changes, thereby varying the orbital radius of the orbiting scroll 26. Therefore, in the scroll compressor 10, the orbital radius of the orbiting scroll 26 is varied by the swing of the bushing 51 around the eccentric shaft 50. In this manner, the eccentric shaft 50, the bushing 51, and the bearing 53 constitute a so-called driven crank mechanism 54 that varies the orbital radius of the orbiting scroll 26. Such a driven crank mechanism 54 is already known.

[0053] Since minute processing errors and assembly errors occur in the fixed scroll 25 and the orbiting scroll 26, a gap (gap) is provided in advance between the fixed spiral wall 25b and the orbiting spiral wall 26b.

[0054] When the motor 22 rotates forward, causing the rotating shaft 15 to rotate in the forward direction, the bushing 51 swings about the eccentric shaft 50 due to the compressive load acting on the orbiting scroll 26. When the bushing 51 swings 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, and the orbital radius of the orbiting scroll 26 increases.

[0055] 3, when the orbital radius of the orbiting scroll 26 increases, the swing of the bushing 51 around the eccentric shaft 50 is restricted at the point when the orbiting spiral wall 26b comes into contact with the fixed spiral wall 25b. This fixes the orbital radius of the orbiting scroll 26.

[0056] Furthermore, 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, causing the orbiting scroll 26 to rotate in the forward direction. When the orbiting spiral wall 26b contacts the fixed spiral wall 25b, the pin 30 and the ring member 29 come into contact with each other. This prevents the orbiting scroll 26 from rotating on its own axis, allowing only the orbiting scroll 26 to revolve in the forward direction. The orbiting scroll 26 then revolves in the forward direction while the orbiting spiral wall 26b is in contact with the fixed spiral wall 25b. This prevents refrigerant leakage from the compression chamber 27, reduces the volume of the compression chamber 27, and compresses the refrigerant.

[0057] When assembling the orbiting scroll 26 to the fixed scroll 25, the bushing 51 is swung around the eccentric shaft 50 in the direction opposite to the direction in which the rotating shaft 15 rotates in the forward direction. This reduces the distance between the center L2 of the bushing 51 and the axis L1 of the rotating shaft 15, thereby reducing the orbital radius of the orbiting scroll 26.

[0058] As shown in Fig. 4, when the orbital radius of the orbiting scroll 26 decreases, the relative position of the orbiting spiral wall 26b with respect to the fixed spiral wall 25b becomes a position where the orbiting spiral wall 26b does not come into contact with the fixed spiral wall 25b. This makes it possible to easily assemble the orbiting scroll 26 to the fixed scroll 25. Fig. 4 shows a state where the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is at its maximum.

[0059] When the bushing 51 swings about the eccentric shaft 50 in the direction opposite to when the rotary shaft 15 is rotating in the forward direction, the bushing 51 is restricted from swinging until the distance between the center L2 of the bushing 51 and the axis L1 of the rotary shaft 15 increases. When the bushing 51 swings about the eccentric shaft 50 in the direction opposite to when the rotary shaft 15 is rotating in the forward direction, the swing of the bushing 51 is restricted when the distance between the center L2 of the bushing 51 and the axis L1 of the rotary shaft 15 becomes the shortest.

[0060] <Normal operation> FIG. 5 shows the change in the rotational speed of the motor 22. As shown in FIG. 5, the control unit 60 pre-stores a program for executing normal operation to drive the motor 22. Therefore, the control unit 60 executes normal operation to drive the motor 22. During normal operation, the control unit 60 drives the motor 22 using sensorless control. During sensorless control, the control unit 60 estimates the position of the rotor 24 from the current flowing through the motor 22 and the input voltage. Then, based on the estimated position of the rotor 24, the control unit 60 converts the current flowing through the motor 22 into a d-axis current, which is an excitation component current, and a q-axis current, which is a torque component current. The control unit 60 controls the on / off of the switching elements so that the d-axis current and the q-axis current reach target values. As a result, during normal operation, the motor 22 rotates at the command rotational speed N1 transmitted from the air conditioning ECU 61.

[0061] <Start-up operation> The control unit 60 pre-stores a program for executing a startup operation in which liquid refrigerant is discharged from the compression mechanism C1 before executing normal operation. Therefore, the control unit 60 executes the startup operation in which liquid refrigerant is discharged 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. The control unit 60 also pre-stores a program for switching from the startup operation to normal operation when the rotation speed of the motor 22 reaches the command rotation speed N1.

[0062] The control unit 60 stores in advance a program for executing reverse rotation startup, which reversely rotates the motor 22, during startup operation. Therefore, during startup operation, the control unit 60 executes reverse rotation startup, which reversely rotates the motor 22. During reverse rotation startup, the control unit 60 swings the bushing 51 so that the orbital radius of the orbiting scroll 26 decreases and the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b increases.

[0063] Specifically, as shown in FIG. 4, in reverse rotation start, the control unit 60 swings the bushing 51 so as to maximize the gap between the fixed volute wall 25b and the orbiting volute wall 26b. In reverse rotation start, the control unit 60 increases the rotational acceleration of the motor 22 and rotates the motor 22 in the reverse direction in order to swing the bushing 51 so as to maximize the gap between the fixed volute wall 25b and the orbiting volute wall 26b. Note that the "rotational acceleration of the motor 22" refers to the amount of change in the rotational speed of the motor 22 per unit time. In reverse rotation start, the bushing 51 swings about the eccentric shaft 50 so as to reduce the distance between the center L2 of the bushing 51 and the axis L1 of the rotary shaft 15. A program that first executes reverse rotation start as a start-up operation when the control unit 60 receives a start-up command from the air conditioning ECU 61 is pre-stored in the control unit 60.

[0064] As shown in FIG. 5 , the control unit 60 pre-stores a program for executing a forward rotation start-up, which rotates the motor 22 forward after executing a reverse rotation start-up, thereby maintaining the orientation of the bushing 51. Therefore, after executing a reverse rotation start-up, the control unit 60 executes a forward rotation start-up, which rotates the motor 22 forward to maintain the orientation of the bushing 51. The slope of the solid line indicating the change in the rotation speed of the motor 22 during forward rotation start-up is gentler than the slope of the solid line indicating the change in the rotation speed of the motor 22 during reverse rotation start-up. Therefore, the amount of change in the rotation speed of the motor 22 per unit time during forward rotation start-up is smaller than the amount of change in the rotation speed of the motor 22 per unit time during reverse rotation start-up. In this way, the control unit 60 reduces the rotational acceleration of the motor 22 during forward rotation start-up compared to when reverse rotation start-up is executed.

[0065] The control unit 60 pre-stores a program for executing liquid discharge startup when the rotation speed of the motor 22 reaches a predetermined rotation speed Nx after performing forward rotation startup. Therefore, the control unit 60 executes liquid discharge startup when the rotation speed of the motor 22 reaches the predetermined rotation speed Nx after performing forward rotation startup. In the liquid discharge startup, the control unit 60 drives the motor 22 at the predetermined rotation speed Nx to cause the orbiting scroll 26 to revolve so as to discharge liquid refrigerant from the compression mechanism C1.

[0066] The control unit 60 pre-stores a program for driving the motor 22 at a predetermined rotation speed Nx during startup, and then executing forward rotation startup after liquid is discharged. Therefore, during startup, the control unit 60 drives the motor 22 at the predetermined rotation speed Nx and then executes forward rotation startup after liquid is discharged. In the forward rotation startup after liquid is discharged, the control unit 60 swings the bushing 51 so that the fixed spiral wall 25b and the orbiting spiral wall 26b are in contact with each other, as shown in FIG. 3.

[0067] 5, the slope of the solid line indicating the change in rotation speed of the motor 22 during forward rotation start after liquid discharge is approximately the same as the slope of the solid line indicating the change in rotation speed of the motor 22 during reverse rotation start. Therefore, the amount of change in the rotation speed of the motor 22 per unit time during forward rotation start after liquid discharge is approximately the same as the amount of change in the rotation speed of the motor 22 per unit time during reverse rotation start. In forward rotation start after liquid discharge, the control unit 60 drives the motor 22 at a predetermined rotation speed Nx, and then increases the rotational acceleration of the motor 22 and rotates the motor 22 in the forward direction to swing the bushing 51 so that the fixed spiral wall 25b and the orbiting spiral wall 26b come into contact with each other.

[0068] The swing direction of the bushing 51 when the forward rotation start after the liquid is discharged is opposite to the swing direction of the bushing 51 when the reverse rotation start is performed. Specifically, when the forward rotation start after the liquid is discharged is performed, 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 rotation shaft 15 increases.

[0069] The control unit 60 pre-stores a program for executing a low-acceleration forward rotation start-up in startup operation, which gradually approaches the rotation speed of the motor 22 to the command rotation speed N1 for normal operation after performing forward rotation start-up after liquid discharge. Therefore, during startup operation, the control unit 60 executes a low-acceleration forward rotation start-up, gradually approaching the rotation speed of the motor 22 to the command rotation speed N1 for normal operation after performing forward rotation start-up after liquid discharge. The slope of the solid line indicating the change in the rotation speed of the motor 22 during low-acceleration forward rotation start-up is gentler than the slope of the solid line indicating the change in the rotation speed of the motor 22 during forward rotation start-up after liquid discharge. Therefore, the change in the rotation speed of the motor 22 per unit time during low-acceleration forward rotation start-up is smaller than the change in the rotation speed of the motor 22 per unit time during forward rotation start-up after liquid discharge. Thus, during low-acceleration forward rotation start-up, the control unit 60 executes a low-acceleration forward rotation start-up, which reduces the rotational acceleration of the motor 22 compared to when forward rotation start-up after liquid discharge is performed, and rotates the motor 22 forward.

[0070] [Operation of the embodiment] Next, the operation of the embodiment will be described. In the scroll compressor 10, the refrigerant may be cooled and liquefied when the scroll compressor 10 is stopped. Therefore, the control unit 60 performs a startup operation to discharge the liquid refrigerant from the compression mechanism C1 before performing a normal operation in which the motor 22 is driven by sensorless control. In the startup operation, the control unit 60 first performs a reverse rotation startup. When the reverse rotation startup is performed, the motor 22 rotates in the reverse direction, thereby reducing the orbital radius of the orbiting scroll 26 and swinging the bushing 51 so as to increase the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b. In this way, the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is increased before the normal operation is performed.

[0071] Next, the control unit 60 executes reverse rotation start and then forward rotation start. In the forward rotation start, the rotational acceleration of the motor 22 is made smaller than that in the reverse rotation start, so that the posture of the bushing 51 is maintained even when the motor 22 is accelerated in the forward rotation. Therefore, even when the motor 22 accelerates in the forward rotation, the large gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is maintained.

[0072] Then, when the control unit 60 executes the forward rotation start and the rotation speed of the motor 22 reaches a predetermined rotation speed Nx, it executes the liquid discharge start, which drives the motor 22 at the predetermined rotation speed Nx to discharge the liquid refrigerant from the compression mechanism C1 and performs the orbital movement of the orbiting scroll 26. In this way, the orbital movement of the orbiting scroll 26 is performed with a large gap between the fixed spiral wall 25b and the orbiting spiral wall 26b, making it difficult for liquid compression to occur in the compression mechanism C1.

[0073] Next, the control unit 60 drives the motor 22 at a predetermined rotation speed Nx, and then executes a forward rotation start-up after liquid discharge. As a result, the fixed volute wall 25b and the orbiting volute wall 26b come into contact with each other. Furthermore, after executing the forward rotation start-up after liquid discharge, the control unit 60 executes a low-acceleration forward rotation start-up. As a result, the rotation speed of the motor 22 gradually approaches the command rotation speed N1 for normal operation. Then, when the rotation speed of the motor 22 reaches the command rotation speed N1, the control unit 60 switches from the startup operation to the normal operation. As a result, the scroll compressor 10 compresses the refrigerant using the compression mechanism C1 during normal operation.

[0074] [Effects of the embodiment] The embodiment can provide the following effects. (1) Before performing normal operation to drive the motor 22, the control unit 60 performs a startup operation to discharge liquid refrigerant from the compression mechanism C1. In the startup operation, the control unit 60 first performs reverse rotation startup. When reverse rotation startup is performed, the motor 22 rotates in reverse, thereby reducing the orbital radius of the orbiting scroll 26 and swinging the bushing 51 to increase the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b. In this way, before performing normal operation, the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is increased. Next, after performing reverse rotation startup, the control unit 60 performs forward rotation startup. In the forward rotation startup, the rotational acceleration of the motor 22 is reduced compared to when reverse rotation startup is performed, so that the orientation of the bushing 51 is maintained even when the motor 22 is accelerated in the forward rotation. Therefore, even when the motor 22 is accelerated in the forward rotation, the large gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is maintained. Then, when the control unit 60 executes forward rotation start and the rotation speed of the motor 22 reaches a predetermined rotation speed Nx, it executes liquid discharge start, which drives the motor 22 at the predetermined rotation speed Nx to cause the orbiting scroll 26 to revolve so as to discharge the liquid refrigerant from the compression mechanism C1. In this manner, the orbiting scroll 26 revolves while the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is large, making it difficult for liquid compression to occur in the compression mechanism C1. As a result, the liquid refrigerant can be efficiently discharged from the compression mechanism C1 while suppressing the loads applied to the fixed spiral wall 25b and the orbiting spiral wall 26b.

[0075] (2) When the control unit 60 executes the reverse rotation start, the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is maximized. Therefore, when the forward rotation start is executed, the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b is maintained at its maximum, and when the liquid discharge start is executed, the orbiting scroll 26 revolves with the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b at its maximum. Therefore, liquid compression is further inhibited in the compression mechanism C1, and liquid refrigerant can be discharged from the compression mechanism C1 while further reducing the loads applied to the fixed spiral wall 25b and the orbiting spiral wall 26b.

[0076] (3) When the control unit 60 executes the forward rotation start after the liquid is discharged, the bushing 51 swings so that the fixed volute wall 25b and the orbiting volute wall 26b come into contact with each other. Therefore, the start-up operation is switched to the normal operation, and preparations for efficient refrigerant compression by the compression mechanism C1 in the normal operation can be smoothly performed.

[0077] (4) In the startup operation, the control unit 60 executes the forward rotation startup after discharging the liquid, and then reduces the rotation acceleration of the motor 22 compared to when the forward rotation startup after discharging the liquid is executed, and rotates the motor 22 in the forward direction. As a result, the rotation speed of the motor 22 gradually approaches the command rotation speed N1 in normal operation, and when the startup operation is switched to normal operation and the control unit 60 executes the normal operation, the motor 22 can be driven with high precision at the command rotation speed N1 in normal operation.

[0078] (5) According to this embodiment, for example, there is no need to reduce the rotation speed of the motor 22 extremely to discharge liquid refrigerant from the compression mechanism C1 in order to suppress the loads applied to the fixed spiral wall 25b and the orbiting spiral wall 26b when starting the scroll compressor 10. Therefore, the start-up responsiveness of the scroll compressor 10 can be improved.

[0079] [Example of change] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0080] In the embodiment, the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b does not have to be maximized during reverse rotation start. In short, during reverse rotation start, the bushing 51 is swung to reduce the orbital radius of the orbiting scroll 26 and increase the gap between the fixed spiral wall 25b and the orbiting spiral wall 26b, and the motor 22 is rotated in the reverse direction.

[0081] In an embodiment, the control unit 60 may not execute the low-acceleration forward rotation startup during the startup operation, but may execute the forward rotation startup after discharging the liquid, and then switch to normal operation when the rotation speed of the motor 22 reaches the command rotation speed N1.

[0082] In the above embodiment, the control unit 60 drives the motor 22 using sensorless control during normal operation. However, this is not limited to this. The control unit 60 may estimate the position of the rotor 24 using a sensor such as a resolver, and may drive the motor 22 accordingly.

[0083] In the above embodiment, the eccentric shaft 50 does not have to be integrally formed with the rotary shaft 15, but may be a separate body from the rotary shaft 15. In this case, the eccentric shaft 50 is attached to the tip surface 15e of the rotary shaft 15.

[0084] In the above embodiment, the balance weight 52 may be separate from the bushing 51 . In the above embodiment, the scroll compressor 10 is used in a vehicle air conditioner, but the use of the scroll compressor 10 is not limited thereto. In short, the scroll compressor 10 may be used in any application as long as it compresses a refrigerant, and the use of the scroll compressor 10 may be changed as appropriate.

[0085] In the above-described embodiment, the object to be compressed by the scroll compressor 10 is not limited to a refrigerant, and may be a fluid such as air. [Explanation of symbols]

[0086] 10...Scroll compressor, 11...Housing, 15...Rotating shaft, 22...Motor, 25...Fixed scroll, 25a...Fixed base plate, 25b...Fixed spiral wall, 26...Orbiting scroll, 26a...Orbiting base plate, 26b...Orbiting spiral wall, 50...Eccentric shaft, 51...Bush, 60...Control unit, C1...Compression mechanism

Claims

1. Housing and a rotation shaft rotatably supported relative to the housing; a motor that rotates the rotary shaft; a control unit that controls the driving of the motor; a compression mechanism driven by the motor and compressing a refrigerant, The compression mechanism includes: a fixed scroll having a disk-shaped fixed base plate and a fixed spiral wall standing upright from the fixed base plate; an orbiting scroll having a disk-shaped orbiting base plate facing the fixed base plate, and an orbiting spiral wall rising from the orbiting base plate toward the fixed base plate and engaging with the fixed spiral wall, and compressing the refrigerant together with the fixed scroll by rotation of the rotation shaft, The rotation shaft is provided with an eccentric shaft extending parallel to the rotation shaft at a position eccentric to the axis of the rotation shaft, a bushing that is swingable around the eccentric shaft is inserted into the eccentric shaft, A scroll compressor in which the orbital radius of the orbiting scroll is variable by swinging the bush around the eccentric shaft, the control unit performs a startup operation to discharge liquid refrigerant from the compression mechanism before performing a normal operation to drive the motor, the startup operation involves: reducing the orbital radius of the orbiting scroll to swing the bushing so as to increase the gap between the fixed spiral wall and the orbiting spiral wall; and executing a reverse rotation startup in which the motor is rotated in reverse; after executing the reverse rotation startup, executing a forward rotation startup in which the rotational acceleration of the motor is reduced compared to when the reverse rotation startup was executed; and rotating the motor in a forward direction to maintain the attitude of the bushing; and when the forward rotation startup has executed and the number of rotations of the motor reaches a predetermined number of rotations, executing a liquid discharge startup in which the motor is driven at the predetermined number of rotations to cause the orbiting scroll to revolve so as to discharge the liquid refrigerant from the compression mechanism.

2. 2. The scroll compressor according to claim 1, wherein the control unit swings the bushing so that a gap between the fixed volute wall and the orbiting volute wall is maximized during the reverse rotation start.

3. 3. The scroll compressor according to claim 1, wherein, in the startup operation, the control unit drives the motor at the predetermined rotation speed and then executes a liquid-discharge forward rotation startup in which the bushing is swung so that the fixed spiral wall and the orbiting spiral wall are in contact with each other.

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

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