Electric compressor

Abstract

Provided is an electric compressor capable of avoiding malfunctions caused by compressing a liquid refrigerant. A scroll compressor is provided with a compression unit, an electric motor, and a control device. The control device includes a motor information detection unit, a storage unit, an estimation unit, and an operation control unit. The control device is connected to a suction pressure sensor for detecting the suction pressure and a discharge pressure sensor for detecting the discharge pressure. The motor information detection unit detects the rotational speed and power consumption of the electric motor. The storage unit stores a map indicating a correspondence relationship among the suction pressure, the discharge pressure, the rotational speed, the power consumption, and the dryness of the refrigerant sucked into the compression unit. The estimation unit estimates the dryness on the basis of the map on the basis of the detected rotational speed, power consumption, suction pressure, and discharge pressure. The operation control unit controls the operation of the electric motor on the basis of the dryness estimated by the estimation unit.

Description

Technical Field

[0001] This invention relates to electric compressors. Background Technology

[0002] Patent Document 1 discloses a refrigeration cycle apparatus. The refrigeration cycle apparatus includes a compressor (which is an electric compressor), a radiator, a pressure control valve, an evaporator, and an accumulator. Furthermore, the refrigeration cycle apparatus includes a refrigerant state estimation unit and a discharge capacity control unit. The compressor compresses the refrigerant and discharges it towards the radiator. The radiator dissipates heat from the refrigerant discharged from the compressor. The pressure control valve causes the refrigerant, after being cooled in the radiator, to depressurize and expand. The evaporator evaporates the refrigerant after depressurization and expansion in the pressure control valve. The accumulator separates the gas and liquid refrigerant flowing from the evaporator. The refrigerant, after being separated into liquid form by the accumulator, is reintroduced into the compressor and compressed.

[0003] The refrigerant state estimation unit estimates the dryness of the refrigerant drawn into the compressor. Using the pressure and temperature of the refrigerant discharged from the compressor, as well as the temperature detected in the evaporator, the refrigerant state estimation unit estimates the enthalpy of the refrigerant drawn into the compressor. Based on this enthalpy, the refrigerant state estimation unit estimates the dryness of the refrigerant drawn into the compressor. The refrigeration cycle unit, through the discharge capacity control unit, controls the compressor drive based on the estimated dryness.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-192090 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when the refrigerant discharged from the electric compressor contains liquid refrigerant, it is difficult to estimate the dryness of the refrigerant drawn into the electric compressor based on the refrigerant's temperature. In other words, in this situation, the electric compressor may continue to operate with liquid refrigerant present in the refrigerant. Therefore, the electric compressor may malfunction due to the compression of liquid refrigerant.

[0009] Methods for solving problems

[0010] An electric compressor for solving the above-mentioned problem includes: a compression section for compressing refrigerant; an electric motor for driving the compression section; and a control device for controlling the electric motor. The control device includes a motor information detection unit for detecting the rotational speed and power consumption of the electric motor, and is connected to an intake pressure sensor and an outlet pressure sensor. The intake pressure sensor detects the intake pressure of the refrigerant drawn into the compression section, and the outlet pressure sensor detects the outlet pressure of the refrigerant discharged from the compression section. The key point of the electric compressor is that... The control device includes: a storage unit that stores a mapping representing the correspondence between the intake pressure, the discharge pressure, the rotational speed, the power consumption, and the dryness of the refrigerant drawn into the compression unit; an estimation unit that estimates the dryness based on the mapping, using the rotational speed and power consumption detected by the motor information detection unit, the intake pressure detected by the intake pressure sensor, and the discharge pressure detected by the discharge pressure sensor; and an operation control unit that controls the operation of the electric motor based on the dryness estimated by the estimation unit.

[0011] Therefore, the control device estimates the dryness of the refrigerant drawn into the compressor section based on the mapping stored in the storage section. In other words, the estimation section estimates the dryness of the refrigerant without referring to the temperature of the refrigerant discharged from the compressor section. Therefore, unlike the case where the estimation section estimates the dryness by referring to the temperature of the refrigerant discharged from the compressor section, the dryness of the refrigerant drawn into the compressor section can be estimated even when the refrigerant contains liquid refrigerant. Thus, the electric compressor can estimate the dryness of the drawn-in refrigerant even when the discharged refrigerant contains liquid refrigerant. The control device controls the electric motor via the operation control section based on the estimated dryness. For example, if the estimation section estimates a dryness that could lead to liquid compression in the compressor section, the control device stops the operation of the electric motor via the operation control section. In this way, the electric compressor can avoid malfunctions caused by the compression of liquid refrigerant.

[0012] In an electric compressor, preferably, the estimation unit estimates the dryness after a predetermined time has elapsed since the electric motor was started.

[0013] The accuracy of power consumption detected by the motor information detection unit improves over time, from the moment the electric motor starts until its operation stabilizes. Therefore, by estimating the dryness after a predetermined time has elapsed since the motor started, the dryness can be estimated with higher accuracy compared to estimating it immediately after the motor starts. In other words, by having the motion control unit control the electric motor after a predetermined time has elapsed since its start, the electric compressor can control the motor with higher precision.

[0014] Furthermore, by controlling the electric motor as described above, the motion control unit can prevent the electric motor from stopping due to "abnormal dryness inferred from the power consumption falsely detected immediately after the electric motor starts." In other words, by controlling the electric motor as described above, the motion control unit in the electric compressor can prevent unexpected stopping of the electric motor.

[0015] In an electric compressor, preferably, the motion control unit stops the electric motor when the dryness estimated by the estimation unit deviates from a predetermined range.

[0016] Therefore, by setting a predetermined range for the allowable dryness of the refrigerant compressed by the compression unit, the electric compressor can avoid compressing refrigerants with undesirable dryness.

[0017] In an electric compressor, it is preferable to have a housing that houses the compression unit, the electric motor, and the control device. The housing includes: an intake port for drawing in the refrigerant to be compressed by the compression unit from outside the housing; and an exhaust port for discharging the compressed refrigerant from the compression unit to the outside of the housing. An intake pressure sensor is disposed at the intake port, and an exhaust pressure sensor is disposed at the exhaust port.

[0018] For example, consider the case where the inhalation pressure sensor and the exhalation pressure sensor are located away from the inhalation port and the exhalation port, respectively. Compared to this case, by arranging the inhalation pressure sensor and the exhalation pressure sensor as described above, the inhalation pressure and exhalation pressure can be detected with higher accuracy.

[0019] Furthermore, the electric compressor is equipped with both a suction pressure sensor and a discharge pressure sensor. Therefore, for the electric compressor, it is possible to estimate the dryness of the refrigerant drawn in from the suction port without having to install new suction and discharge pressure sensors on the refrigeration cycle containing the electric compressor.

[0020] Invention Effects

[0021] According to the present invention, it is possible to avoid malfunctions caused by compressing liquid refrigerant. Attached Figure Description

[0022] Figure 1 This is a side view showing the vehicle and its air conditioning system.

[0023] Figure 2 This is a diagram showing the cooling cycle of a vehicle's air conditioning system.

[0024] Figure 3 This is a cross-sectional view showing an electric compressor.

[0025] Figure 4 This is a block diagram showing the control device.

[0026] Figure 5 This is a flowchart illustrating the control performed by the control device.

[0027] Explanation of reference numerals in the attached figures

[0028] 10…Scroll compressor as an electric compressor, 20…Housing, 23c…Suction port, 25d…Discharge port, 30…Compression section, 40…Electric motor, 50…Control device, 51…Motor information detection section, 52…Storage section, 53…Estimation section, 54…Action control section, 61…Suction pressure sensor, 62…Discharge pressure sensor. Detailed Implementation

[0029] The following describes one embodiment of the electric compressor. The electric compressor in this embodiment is a scroll compressor. The scroll compressor is part of a vehicle air conditioning system installed in a vehicle.

[0030] <Vehicles and vehicle air conditioning systems>

[0031] like Figure 1 As shown, the vehicle 100 is equipped with a vehicle air conditioning device 101. The vehicle air conditioning device 101 regulates the air in the vehicle 100's cabin.

[0032] like Figure 2 As shown, the vehicle air conditioning system 101 includes a refrigeration cycle C. The refrigeration cycle C consists of a scroll compressor 10 (which is an electric compressor), a condenser 11, an expansion valve 12, and an evaporator 13. That is, the scroll compressor 10 is mounted on the vehicle 100 and used in the vehicle air conditioning system 101. Refrigerant is sealed inside the refrigeration cycle C. The refrigerant flows inside the refrigeration cycle C. The refrigerant passes sequentially through the scroll compressor 10, the condenser 11, the expansion valve 12, and the evaporator 13. After passing through the evaporator 13, the refrigerant flows towards the scroll compressor 10. In other words, the refrigerant circulates within the refrigeration cycle C.

[0033] High-temperature, high-pressure gaseous refrigerant flows from the scroll compressor 10 into the condenser 11. The condenser 11 is configured to condense the refrigerant internally. The condenser 11 condenses the refrigerant by dissipating the heat contained in the refrigerant to its surroundings. More specifically, the condenser 11 internally condenses the high-temperature, high-pressure gaseous refrigerant into a low-temperature, high-pressure liquid phase. That is, low-temperature, high-pressure liquid refrigerant flows out of the condenser 11.

[0034] The refrigerant flowing from the condenser 11 flows into the expansion valve 12. More specifically, a low-temperature, high-pressure liquid phase of refrigerant flows into the expansion valve 12. The expansion valve 12 is configured to depressurize the refrigerant passing through it. That is, the refrigerant expands from a low-temperature, high-pressure liquid phase to a low-temperature, low-pressure liquid phase as it passes through the expansion valve 12.

[0035] The refrigerant, after passing through expansion valve 12, flows into evaporator 13. More specifically, a low-temperature, low-pressure liquid refrigerant flows into evaporator 13. Evaporator 13 is configured to evaporate the refrigerant internally. Evaporator 13 evaporates the refrigerant by absorbing heat from its surroundings and transferring that heat to the refrigerant. More specifically, evaporator 13 internally vaporizes the low-temperature, low-pressure liquid refrigerant into a high-temperature, low-pressure gaseous refrigerant. Evaporator 13 cools its surroundings through this vaporization process. The refrigerant after passing through evaporator 13 is drawn into scroll compressor 10.

[0036] <Overall Overview of Scroll Compressors>

[0037] like Figure 3 As shown, the scroll compressor 10 includes a housing 20, a compression section 30, an electric motor 40, and a control device 50. The housing 20 houses a rotating shaft 21, a support section 22 that supports the rotating shaft 21 via a first bearing 71, the compression section 30, and the electric motor 40. In other words, the housing 20 houses the compression section 30, the electric motor 40, and the control device 50.

[0038] The rotating shaft 21 has an eccentric shaft 21a at one end. The eccentric shaft 21a protrudes along the axial direction from a position eccentric to the axis L1 of the rotating shaft 21. The rotating shaft 21 is connected to the counterweight 21b via the eccentric shaft 21a.

[0039] The housing 20 consists of a motor housing 23, a fixed base plate 24, an output housing 25, and a converter cover 26.

[0040] The motor housing 23 has an end wall 23a, a peripheral wall 23b, and a suction port 23c. The end wall 23a forms one of the ends of the motor housing 23 in the axial direction. The peripheral wall 23b extends cylindrically from the outer periphery of the end wall 23a. The axial direction of the peripheral wall 23b is consistent with the axial direction of the rotating shaft 21.

[0041] The rotating shaft 21 is rotatably inserted into the end wall 23a via the second bearing 72. One end of the rotating shaft 21 is supported on the end wall 23a, and the other end is supported on the support portion 22.

[0042] A suction port 23c is provided on the peripheral wall 23b. That is, the housing 20 has a suction port 23c. The suction port 23c is a portion protruding from the outer peripheral surface of the peripheral wall 23b. The suction port 23c is connected to the evaporator 13. The suction port 23c is provided to draw refrigerant flowing from the evaporator 13 into the interior of the housing 20. A suction pressure sensor 61 is provided in the suction port 23c. The suction pressure sensor 61 is configured to detect the pressure of the refrigerant drawn into the interior of the housing 20 from the suction port 23c.

[0043] The fixing base plate 24 is disposed on the end opposite to the end connected to the end wall 23a in the peripheral wall 23b. A fixing scroll wall 24a is erected on the fixing base plate 24. The fixing scroll wall 24a rises from the fixing base plate 24 toward the interior of the peripheral wall 23b. The fixing base plate 24 and the fixing scroll wall 24a constitute the fixing scroll member 31.

[0044] The fixed substrate 24 has a discharge hole 24b. The discharge hole 24b extends through the fixed substrate 24 in the thickness direction.

[0045] The ejector housing 25 is connected to the opposite side of the fixed substrate 24, on which the fixed vortex wall 24a is erected, via a gasket 27. The gasket 27 seals the ejector housing 25 and the fixed substrate 24.

[0046] The discharge housing 25 has a discharge chamber 25a and a discharge port 25d. That is, the housing 20 has a discharge port 25d.

[0047] The discharge chamber 25a is defined by the discharge housing 25 and the fixed substrate 24. The discharge chamber 25a communicates with the discharge hole 24b. The discharge housing 25 has a discharge hole 25e in the portion opposite to the fixed substrate 24. The discharge hole 25e communicates with the discharge hole 24b via the discharge chamber 25a.

[0048] Discharge port 25d is connected to condenser 11. Discharge port 25d is provided for discharging refrigerant from the inside of housing 20 toward condenser 11. Discharge pressure sensor 62 is provided in discharge port 25d. Discharge pressure sensor 62 is configured to detect the pressure of the refrigerant discharged from discharge port 25d to condenser 11.

[0049] <Compression section and electric motor>

[0050] The scroll compressor 10 compresses the refrigerant drawn in from the suction port 23c via a compression section 30. The compression section 30 is located in the motor housing 23, near the fixed base plate 24 in the axial direction. The compression section 30 consists of a fixed scroll member 31, a rotating scroll member 32, and a compression chamber 30a.

[0051] The rotating scroll member 32 is arranged opposite to the fixed scroll member 31. The rotating scroll member 32 is composed of a rotating base plate 32a facing the fixed base plate 24 and a rotating scroll wall 32b erected on the rotating base plate 32a. The rotating scroll wall 32b is erected from the rotating base plate 32a toward the fixed base plate 24. The fixed scroll member 31 and the rotating scroll member 32 are arranged such that the fixed scroll wall 24a and the rotating scroll wall 32b are engaged.

[0052] A thrust plate 28 is provided between the rotating base plate 32a and the support portion 22.

[0053] The counterweight 21b is connected to the opposite side of the rotating base plate 32a, on which the rotating vortex wall 32b is erected, via the third bearing 73. The rotating base plate 32a is supported on the eccentric shaft 21a via the bushing of the counterweight 21b and the third bearing 73 in a manner that allows it to rotate relative to the eccentric shaft 21a.

[0054] Four ring members 33 are mounted on the surface of the rotating base plate 32a facing the thrust plate 28. Anti-rotation pins 22a protruding from the support portion 22 and passing through the thrust plate 28 are inserted into the inner side of each ring member 33.

[0055] The compression chamber 30a is formed between the fixed scroll member 31 and the rotating scroll member 32 through the engagement of the fixed scroll wall 24a and the rotating scroll wall 32b. The compression chamber 30a is connected to the discharge port 24b.

[0056] An electric motor 40 is housed inside a motor housing 23. The electric motor 40 is disposed within a space defined by a support portion 22, an end wall 23a, and a peripheral wall 23b within the motor housing 23. This space will hereafter be referred to as the motor chamber 23e. The motor chamber 23e is the portion within the peripheral wall 23b closest to the end wall 23a. The motor chamber 23e is connected to the compression chamber 30a via a notch 23f formed on the inner peripheral surface of the peripheral wall 23b. In other words, refrigerant drawn in from the suction port 23c passes sequentially through the motor chamber 23e, the notch 23f, the compression chamber 30a, and the discharge chamber 25a, and is then discharged from the discharge port 25d.

[0057] The electric motor 40 has a stator 41 and a rotor 42 disposed inside the stator 41. A rotating shaft 21 is inserted through the rotor 42. The rotor 42 rotates integrally with the rotating shaft 21. The stator 41 surrounds the rotor 42.

[0058] The electric motor 40 rotates the rotor 42, thereby rotating the rotating shaft 21. The rotation of the rotating shaft 21 is transmitted to the rotating scroll member 32 via the eccentric shaft 21a, the bushing of the counterweight 21b, and the third bearing 73. At this time, the rotation of the rotating scroll member 32 is prevented by the contact between each anti-rotation pin 22a and the inner circumferential surface of each ring member 33. As a result, the rotating scroll member 32 revolves relative to the fixed scroll member 31. The rotating scroll member 32 revolves while contacting the rotating scroll wall 32b with the fixed scroll wall 24a. Therefore, the volume of the compression chamber 30a decreases with the revolution of the rotating scroll member 32.

[0059] In the scroll compressor 10, refrigerant drawn in from outside the housing 20 through the suction port 23c passes through the motor chamber 23e and the notch 23f, and is then introduced into the outermost periphery of the compression chamber 30a. The refrigerant introduced into the compression chamber 30a is compressed within the compression chamber 30a by the revolution of the rotating scroll member 32. The refrigerant compressed by the compression section 30 passes through the discharge port 24b, the discharge chamber 25a, and the discharge port 25e, and is then discharged from the discharge port 25d to the outside of the housing 20. As described above, the scroll compressor 10 compresses the refrigerant using the compression section 30. In other words, the compression section 30 compresses the refrigerant. Furthermore, the scroll compressor 10 compresses the refrigerant drawn in from the suction port 23c using the compression section 30, and then discharges it from the discharge port 25d to the outside of the housing 20. That is, the suction port 23c draws in refrigerant from outside the housing 20 to be compressed by the compression section 30. Additionally, the refrigerant compressed by the compression section 30 is discharged from the discharge port 25d to the outside of the housing 20. Therefore, the suction pressure sensor 61 detects the suction pressure of the refrigerant drawn into the compression section 30, and the discharge pressure sensor 62 detects the pressure of the refrigerant discharged from the compression section 30. Here, the suction pressure is the pressure of the refrigerant at the suction port 23c. The discharge pressure is the pressure of the refrigerant at the discharge port 25d.

[0060] <Control Device>

[0061] The converter housing 26 is mounted on the end wall 23a. The control device 50 is housed in the space defined by the converter housing 26 and the end wall 23a.

[0062] like Figure 4 As shown, the control device 50 is connected to the electric motor 40, the inhalation pressure sensor 61, and the exhalation pressure sensor 62. The inhalation pressure detected by the inhalation pressure sensor 61 and the exhalation pressure detected by the exhalation pressure sensor 62 are input to the control device 50.

[0063] The control device 50 controls the electric motor 40. More specifically, the control device 50 controls the electric motor 40 by outputting a rotational speed as a command value to the electric motor 40. The control device 50 is powered by a power source (not shown) located outside the housing 20. The control device 50 is driven by this power.

[0064] The control device 50 includes a motor information detection unit 51, a storage unit 52, an estimation unit 53, and an action control unit 54. The control device 50 includes a processor (not shown). Examples of processors include a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a DSP (Digital Signal Processor). The storage unit 52 includes RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit 52 stores program code or instructions configured to cause the processor to execute processing. The storage unit 52 includes any usable medium accessible by a general-purpose or special-purpose computer. The control device 50 may also be constructed from hardware circuits such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays). The control device 50, as a processing circuit, may include one or more processors, ASICs, FPGAs, or other hardware circuits, or combinations thereof, that operate according to a computer program.

[0065] The motor information detection unit 51 detects the rotational speed and power consumption of the electric motor 40. For example, the motor information detection unit 51 is connected to a speed sensor (not shown) and detects the rotational speed via this sensor. The motor information detection unit 51 calculates the power consumption of the electric motor 40 based on the current and voltage in a converter device (not shown) included in the control device 50, and then detects this power consumption. The control device 50 obtains the rotational speed and power consumption of the electric motor 40 detected by the motor information detection unit 51. Thereafter, the rotational speed of the electric motor 40 is recorded only as rotational speed. Furthermore, thereafter, the power consumption of the electric motor 40 is recorded only as power consumption.

[0066] While the scroll compressor 10 is operating, the suction pressure and discharge pressure are input to the control device 50, and the control device 50 obtains the rotational speed and power consumption. The input of suction pressure and discharge pressure to the control device 50, and the obtaining of rotational speed and power consumption by the control device 50, are continuous. In other words, the values ​​of the suction pressure and discharge pressure input to the control device 50, and the rotational speed and power consumption obtained by the control device 50, can change continuously over time. Alternatively, the input of suction pressure and discharge pressure to the control device 50, and the obtaining of rotational speed and power consumption by the control device 50, can also be performed at regular intervals. In short, the control device 50 only needs to be configured to obtain the values ​​of suction pressure, discharge pressure, rotational speed, and power consumption that vary according to the operating conditions of the scroll compressor 10.

[0067] Storage unit 52 stores a mapping. The mapping represents the correspondence between suction pressure, discharge pressure, rotational speed, power consumption, and the dryness of the refrigerant drawn into compressor unit 30. In other words, the mapping represents the correspondence between the values ​​of suction pressure, discharge pressure, rotational speed, and power consumption in scroll compressor 10 and the value of the dryness of the refrigerant drawn into compressor unit 30. Here, dryness refers to the weight ratio of the gaseous component in the refrigerant. That is, a refrigerant with lower dryness contains more liquid refrigerant. When the values ​​of suction pressure, discharge pressure, rotational speed, and power consumption in scroll compressor 10 are uniquely determined, the mapping represents the dryness of a refrigerant drawn into compressor unit 30. Hereinafter, the dryness of the refrigerant drawn into compressor unit 30 will only be referred to as dryness.

[0068] The mapping is created by simulating the operation of the scroll compressor 10 under multiple conditions. Specifically, the mapping is created using the method described below. First, the values ​​of suction pressure, discharge pressure, dryness fraction, and rotational speed are set. Next, the power consumption required to achieve the combination of these values ​​in the scroll compressor 10 is calculated through simulation. By performing this simulation while varying the values ​​of suction pressure, discharge pressure, dryness fraction, and rotational speed, the power consumption for various combinations of suction pressure, discharge pressure, dryness fraction, and rotational speed can be obtained. By processing the results with respect to dryness fraction, the aforementioned mapping can be obtained.

[0069] The estimation unit 53 estimates the dryness of the refrigerant drawn into the compressor unit 30 based on a mapping. The estimation unit 53 estimates the dryness according to the mapping while referring to the values ​​input to it. More specifically, the speed and power consumption detected by the motor information detection unit 51, and the suction pressure and discharge pressure detected by the suction pressure sensor 61 and discharge pressure sensor 62 are input to the estimation unit 53. That is, the estimation performed by the estimation unit 53 uses the speed and power consumption detected by the motor information detection unit 51, the suction pressure detected by the suction pressure sensor 61, and the discharge pressure detected by the discharge pressure sensor 62. More specifically, the estimation unit 53 refers to the respective values ​​of the suction pressure, discharge pressure, speed, and power consumption input to it, and obtains the dryness corresponding to each of these values ​​in the mapping. The estimation unit 53 estimates the obtained dryness as the dryness of the refrigerant drawn into the scroll compressor 10. Furthermore, the estimation unit 53 does not estimate the dryness based on the temperature of the refrigerant. In other words, the estimation unit 53 does not estimate the dryness based on the temperature of the refrigerant.

[0070] The estimation unit 53 is configured to measure the time elapsed since the electric motor 40 started. For example, the control device 50 includes a timer (not shown), and the estimation unit 53 refers to the measurement result of this timer. Alternatively, the estimation unit 53 may refer to the measurement result of a timer provided externally to the control device 50. The estimation unit 53 estimates the dryness after a predetermined time has elapsed since the electric motor 40 started. In this embodiment, the predetermined time is the time until the detection error of the power consumption of the electric motor 40 detected by the motor information detection unit 51 reaches within an acceptable range. In this embodiment, the predetermined time is preset by the control device 50.

[0071] The motion control unit 54 controls the operation of the electric motor 40 based on the dryness estimated by the estimation unit 53. More specifically, the motion control unit 54 stops the electric motor 40 when the dryness estimated by the estimation unit 53 deviates from a predetermined range. In this embodiment, the predetermined range is the range of dryness of the refrigerant that is permissible for compression in the compression unit 30. For example, the predetermined range is set based on the range of dryness permissible for compression in the compression unit 30. In this embodiment, the predetermined range is preset by the motion control unit 54.

[0072] The motion control unit 54 does not control the operation of the electric motor 40 until a predetermined time has elapsed. In other words, the motion control unit 54 controls the operation of the electric motor 40 during the period when the dryness is estimated by the estimation unit 53.

[0073] <Control device for electric motor>

[0074] use Figure 4 as well as Figure 5 This illustrates the control device 50's control over the electric motor 40.

[0075] The operation of the electric motor 40 and the control of the electric motor 40 by the control device 50 are in Figure 1 The vehicle air conditioning system 101 shown starts simultaneously with its activation.

[0076] After the electric motor 40 starts, in step S1, the control device 50 determines whether the time elapsed since the electric motor 40 started is within a preset time. The control device 50 performs the processing in step S1 until the time elapsed since the electric motor 40 started exceeds the preset time.

[0077] If the time elapsed since the start of the electric motor 40 exceeds a predetermined time, the control device 50 performs step S2. In step S2, the control device 50 estimates the dryness by the estimation unit 53 based on the value obtained by the motor information detection unit 51 and the values ​​input by the inhalation pressure sensor 61 and the exhaust pressure sensor 62.

[0078] After the estimation unit 53 estimates the dryness, the control device 50 performs step S3. In step S3, the control device 50 determines whether the estimated dryness is within a predetermined range. If the estimated dryness is within the predetermined range, the control device 50 performs step S4. In step S4, the control device 50 determines whether the electric motor 40 is stopped. If the electric motor 40 is not stopped, the control device 50 moves from step S4 to step S2 and performs the subsequent steps of step S2 again. In other words, the control device 50 performs the dryness estimation by the estimation unit 53 until the electric motor 40 stops, provided the estimated dryness is within the predetermined range.

[0079] If the dryness estimated in step S3 by the control device 50 falls outside the predetermined range, the control device 50 proceeds to step S5. In step S5, the control device 50 stops the operation of the electric motor 40 via the operation control unit 54. After stopping the operation of the electric motor 40, the control device 50 proceeds to step S4. In this case, since the electric motor 40 has stopped operating, the control device 50 terminates the control of the electric motor 40 after performing the determination in step S4.

[0080] Furthermore, for example, at the point in time when the driver of vehicle 100 performs an operation to stop the vehicle's air conditioning system 101, the control device 50, regardless of the ongoing operation... Figure 5 Each of the steps S1 to S5 shown will stop the operation of the electric motor 40.

[0081] [Effects of this implementation method]

[0082] The effects and functions of this implementation method will be explained together.

[0083] (1) The control device 50 estimates the dryness of the refrigerant drawn into the compressor 30 based on the mapping stored in the storage unit 52 by the estimation unit 53. That is, the estimation unit 53 estimates the dryness of the refrigerant without referring to the temperature of the refrigerant discharged from the compressor 30. Therefore, unlike the case where the estimation unit 53 estimates the dryness by referring to the temperature of the refrigerant discharged from the compressor 30, the dryness of the refrigerant drawn into the compressor 30 can be estimated even if the refrigerant contains liquid refrigerant. Therefore, in the scroll compressor 10, the dryness of the drawn refrigerant can be estimated even if the discharged refrigerant contains liquid refrigerant. The control device 50 controls the electric motor 40 by the operation control unit 54 according to the estimated dryness. For example, if the estimation unit 53 estimates that the dryness is likely to cause liquid compression in the compressor 30, the control device 50 stops the operation of the electric motor 40 by the operation control unit 54. In this way, in the scroll compressor 10, it is possible to avoid malfunctions caused by compressing liquid refrigerant.

[0084] (2) The accuracy of the power consumption detected by the motor information detection unit 51 increases over time from the moment the electric motor 40 starts until the operation of the electric motor 40 stabilizes. Therefore, by estimating the dryness by the estimation unit 53 after a predetermined time has elapsed since the electric motor 40 starts, the dryness can be estimated with higher accuracy compared to estimating the dryness immediately after the electric motor 40 starts. In other words, by controlling the electric motor 40 after a predetermined time has elapsed since the scroll compressor 10 starts, the control device 50 can control the electric motor 40 with higher accuracy.

[0085] (3) After a predetermined time has elapsed since the start of the electric motor 40, the control device 50 uses the estimation unit 53 to estimate the dryness. As a result, the control device 50 can avoid the situation where "the electric motor 40 stops based on the abnormal dryness estimated based on the power consumption falsely detected immediately after the start of the electric motor 40".

[0086] (4) The scroll compressor 10 can avoid compressing refrigerants with undesirable dryness by setting the range of permissible dryness for the refrigerant compressed by the compression section 30 to a predetermined range.

[0087] (5) For example, consider the case where the inhalation pressure sensor 61 and the exhalation pressure sensor 62 are respectively located away from the inhalation port 23c and the exhalation port 25d. Compared with this case, by arranging the inhalation pressure sensor 61 and the exhalation pressure sensor 62 as in the embodiment, the inhalation pressure and the exhalation pressure can be detected with higher accuracy.

[0088] (6) A suction pressure sensor 61 and a discharge pressure sensor 62 are provided for the scroll compressor 10. Therefore, for the scroll compressor 10, the dryness of the refrigerant drawn in from the suction port 23c can be estimated without adding a new suction pressure sensor 61 and discharge pressure sensor 62 to the refrigeration cycle C containing the scroll compressor 10.

[0089] (7) Regarding the scroll compressor 10, there is no need to install a new suction pressure sensor 61 and discharge pressure sensor 62 in the refrigeration cycle C using the scroll compressor 10, so the refrigeration cycle C can be miniaturized. Therefore, the scroll compressor 10 can achieve miniaturization of the vehicle air conditioning device 101 including the scroll compressor 10.

[0090] [Example of Change]

[0091] Furthermore, the above embodiments can be implemented by modification as follows. The above embodiments and the following modifications can be combined with each other to implement them within the scope of technical inconsistency.

[0092] The scroll compressor 10 may not be mounted on the vehicle 100. Alternatively, the scroll compressor 10 may not be used in the vehicle air conditioning unit 101. For example, the scroll compressor 10 may also be used in a stationary air conditioning unit.

[0093] The suction pressure sensor 61 can also detect the pressure of the refrigerant inside the scroll compressor 10, downstream of the suction port 23c and upstream of the compression chamber 30a. In this case, the suction pressure sensor 61 is located in the housing 20 upstream of the compression section 30. For example, the suction pressure sensor 61 can also detect the refrigerant pressure in the motor chamber 23e.

[0094] ○ The suction pressure sensor 61 may not be located at the suction port 23c. For example, the suction pressure sensor 61 may be located on the refrigeration cycle C, downstream of the evaporator 13 and upstream of the suction port 23c. As long as the suction pressure sensor 61 is located at a position that can detect the pressure of the refrigerant before it is compressed by the compressor 30.

[0095] The discharge pressure sensor 62 can also detect the pressure of the refrigerant inside the scroll compressor 10, upstream of the discharge port 25d and downstream of the compression chamber 30a. In this case, the discharge pressure sensor 62 is located in the portion of the housing 20 downstream of the compression section 30. For example, the discharge pressure sensor 62 can also detect the pressure of the refrigerant in the discharge chamber 25a.

[0096] The discharge pressure sensor 62 may not be located at the discharge port 25d. For example, the discharge pressure sensor 62 may be located on the refrigeration cycle C, upstream of the condenser 11 and downstream of the discharge port 25d. As long as the discharge pressure sensor 62 is located at a position that can detect the pressure of the refrigerant compressed by the compression unit 30.

[0097] The motion control unit 54 may also prevent the electric motor 40 from stopping if the dryness of the refrigerant estimated by the estimation unit 53 deviates from a predetermined range. For example, in this case, the motion control unit 54 may change the speed of the electric motor 40 in a manner that keeps the estimated dryness within a predetermined range.

[0098] The estimation unit 53 can also estimate the dryness immediately after the electric motor 40 is started.

[0099] The method for creating the mapping is not limited to the method of this embodiment. For example, the mapping can also be created by using machine learning of the relationship between inhalation pressure, exhalation pressure, rotational speed, power consumption, and dryness obtained through simulation as teacher data.

[0100] ○ The motor information detection unit 51 may not be connected to the speed sensor. For example, the motor information detection unit 51 may also detect the command value output by the control device 50.

[0101] The electric compressor is not limited to the scroll compressor 10. For example, the electric compressor may also be a centrifugal compressor. In this case, the compression section 30 includes multiple impellers and a diffusion path.

[0102] [Postscript]

[0103] The following describes the technical ideas that can be grasped from the above-described embodiments and variations.

[0104] <Note 1> An electric compressor, which is mounted on a vehicle and used in a vehicle air conditioning system.

[0105] <Note 2> An electric compressor includes a housing that houses the compression section, the electric motor, and the control device. The suction pressure sensor is disposed in a portion of the housing upstream of the compression section, and the discharge pressure sensor is disposed in a portion of the housing downstream of the compression section.

[0106] <Note 3> An electric compressor in which the estimation unit does not estimate the dryness based on the temperature of the refrigerant.

Claims

1. An electric compressor comprising: a compression unit that compresses refrigerant; an electric motor that drives the compression unit; and a control device that controls the electric motor, the control device comprising a motor information detection unit that detects a rotational speed and a consumed power of the electric motor, and is connected to a suction pressure sensor that detects a suction pressure of the refrigerant sucked into the compression unit and a discharge pressure sensor that detects a discharge pressure of the refrigerant discharged from the compression unit, the control device comprising: a storage unit that stores a map indicating a correspondence relationship between the suction pressure, the discharge pressure, the rotational speed, the consumed power, and a dryness of the refrigerant sucked into the compression unit; an estimation unit that estimates the dryness based on the map, based on the rotational speed and the consumed power detected by the motor information detection unit, the suction pressure detected by the suction pressure sensor, and the discharge pressure detected by the discharge pressure sensor; and an operation control unit that controls an operation of the electric motor based on the dryness estimated by the estimation unit.

2. The electric compressor according to claim 1, wherein the estimation unit estimates the dryness after a predetermined time elapses from a start of the electric motor.

3. The electric compressor according to claim 1 or 2, wherein the operation control unit stops the electric motor when the dryness estimated by the estimation unit deviates from a predetermined range.

4. The electric compressor according to claim 1 or 2, comprising a housing that accommodates the compression unit, the electric motor, and the control device, the housing comprising: a suction port that sucks the refrigerant to be compressed by the compression unit from an outside of the housing; and a discharge port that discharges the refrigerant compressed by the compression unit to the outside of the housing, the suction pressure sensor being provided to the suction port, and the discharge pressure sensor being provided to the discharge port. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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