Lubrication system

Abstract

To provide a lubrication system that can raise the temperature of oil speedily without using a device such as a heater for oil heating.SOLUTION: A lubrication system comprises a three-phase motor 70 which drives a pump capable of supplying oil to a lubricated object to be lubricated with the oil, a switch 90 which is installed on wiring electrically connected to a neutral point 84 of the three-phase motor 70, and a control part which can open and close the switch 90, and the control part can perform temperature-raising control to supply electric power to at least one of a plurality of coils 78 that the three-phase motor 70 comprises by closing the switch 90 and then raise the temperature of the oil with heat generated by the coils 78.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to lubrication systems. [Background technology]

[0002] In recent years, research and development into electrification technologies that contribute to energy efficiency has been conducted to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 discloses that heat generated by a motor is used to raise the temperature of oil that lubricates an object to be lubricated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent Application Publication No. 113864434 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to heat the lubricating oil more quickly, it is conceivable to use a device such as a heater for heating the oil separately from the motor drive circuit. However, using a device such as a heater increases weight and space. Therefore, it is desirable to heat the oil quickly without using a device such as a heater for heating the oil.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] An aspect of the present disclosure is a lubrication system comprising: a three-phase motor that drives a pump that can supply oil to an object that is lubricated by the oil; a switch provided on wiring electrically connected to the neutral point of the three-phase motor; and a control unit that can open and close the switch, wherein the control unit can supply power to at least one of a plurality of coils provided in the three-phase motor by closing the switch, and can perform temperature control that raises the temperature of the oil using heat generated from the coil. [Effects of the Invention]

[0008] According to the present invention, the temperature of the oil can be increased more quickly. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a flying vehicle. [Figure 2] FIG. 2 is a schematic diagram of the lubrication system. [Figure 3] FIG. 3 is a circuit diagram of the power plant according to this embodiment. [Figure 4] FIG. 4 is a diagram showing current paths in a power plant of a comparative example. [Figure 5] FIG. 5 is a diagram showing current paths in the power plant of this embodiment. [Figure 6] FIG. 6 is a flowchart of the energization determination process performed by the control unit. [Figure 7] FIG. 7 is a diagram showing the change in oil temperature over time. [Figure 8] FIG. 8 is a diagram showing a three-phase motor and a first pump according to a first modified example. [Figure 9] FIG. 9 is a schematic diagram of a lubrication system according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] [1 Aircraft 10] FIG. 1 is a schematic diagram of an air vehicle 10. The air vehicle 10 is an electric vertical take-off and landing aircraft (eVTOL aircraft). The air vehicle 10 has eight VTOL rotors 12. The VTOL rotors 12 generate thrust in an upward direction relative to the airframe 14. The air vehicle 10 has eight electric motors 16. One electric motor 16 drives one VTOL rotor 12. The air vehicle 10 has two cruise rotors 18. The cruise rotor 18 generates thrust in a forward direction relative to the airframe 14. The air vehicle 10 has four electric motors 20. Two electric motors 20 drive one cruise rotor 18.

[0011] The aircraft 10 is equipped with a gas turbine engine 22 and a generator 24. The gas turbine engine 22 drives the generator 24. The generator 24 generates electricity. The electricity generated by the generator 24 is supplied to load devices (electric motors 16, 20, etc.) and a capacitor (not shown) provided on the aircraft 10. The gas turbine engine 22 and the generator 24 form part of a lubrication system 28 shown in FIG. 2.

[0012] [2. Lubrication System 28 Components] 2 is a schematic diagram of the lubrication system 28. In the lubrication system 28 of this embodiment, the object to be lubricated by oil is the generator 24 mounted on the aircraft 10. However, the object to be lubricated by oil is not limited to the generator 24. The lubrication system 28 includes a lubrication circuit 30, a power unit 32, and a control unit 34.

[0013] The lubrication circuit 30 includes a generator 24 and a tank 36. The generator 24 includes an oil inlet 24i and an oil outlet 24o. Oil flows into the generator 24 through the oil inlet 24i and flows out of the generator 24 through the oil outlet 24o. The oil circulates between the tank 36 and the generator 24.

[0014] The lubrication circuit 30 includes a first pump 38, a flow path 40, and a flow path 42. The first pump 38 includes an intake port 38i and a discharge port 38d. The intake port 38i is connected to the tank 36 via the flow path 40. The discharge port 38d is connected to an oil inlet 24i of the generator 24 via the flow path 42. The first pump 38 can supply oil drawn from the tank 36 via the flow path 40 to the generator 24 via the flow path 42. The first pump 38 is a feed pump.

[0015] The lubrication circuit 30 includes a second pump 46, a flow path 48, and a flow path 50. The second pump 46 includes an intake port 46i and a discharge port 46d. The intake port 46i is connected to the oil outlet 24o of the generator 24 via the flow path 48. The discharge port 46d is connected to the tank 36 via the flow path 50. The second pump 46 can discharge oil recovered (sucked) from the generator 24 via the flow path 48 into the tank 36 via the flow path 50. The second pump 46 is a scavenge pump.

[0016] The lubrication circuit 30 includes a relief valve 54, a flow path 56, a flow path 58, an oil chamber (oil reservoir) 60, and a flow path 62. The relief valve 54 includes an inlet 54i and an outlet 54o. The inlet 54i is connected to the flow path 42 via the flow path 56. The outlet 54o is connected to the inlet 60i of the oil chamber 60 via the flow path 58. The relief valve 54 opens when the oil pressure value on the primary side (flow path 56, flow path 42) exceeds a predetermined valve opening pressure value. This allows the relief valve 54 to communicate with the flow path 56 and the flow path 58. The relief valve 54 can release oil in the flow path 42 to the oil chamber 60 via the flow path 58.

[0017] The oil chamber 60 has an inlet 60i and an outlet 60o. The inlet 60i is connected to the outlet 54o of the relief valve 54 via a passage 58. The outlet 60o is connected to the tank 36 via a passage 62.

[0018] In this embodiment, the lubrication circuit 30 is provided with one first pump 38, but may be provided with two or more first pumps 38. Similarly, the lubrication circuit 30 may be provided with two or more second pumps 46.

[0019] The rotary shafts of the first pump 38 and the second pump 46 are connected to the rotary shaft of a three-phase motor 70 provided in the power unit 32. By driving the first pump 38 and the second pump 46 on the same shaft as in this embodiment, the lubrication circuit 30 can be made compact.

[0020] 3 is a circuit diagram of the power unit 32 according to this embodiment. The power unit 32 includes a power supply 66, a power conversion device 68, a three-phase motor 70, a shunt resistor 72, and a connection circuit 74. The power supply 66 may supply DC power to the power conversion device 68. The power supply 66 may be, for example, a battery. The power conversion device 68 may convert the DC power supplied from the power supply 66 into AC power and supply it to the three-phase motor 70. The power conversion device 68 may be, for example, an inverter. The three-phase motor 70 may be driven by the AC power supplied from the power conversion device 68.

[0021] The positive terminal 66p of the power supply 66 is electrically connected to a positive terminal 68p on the primary side of the power converter 68. The negative terminal 66n of the power supply 66 is electrically connected to ground GND. The negative terminal 68n on the primary side of the power converter 68 is electrically connected to a first end 72a of a shunt resistor 72. The U-phase terminal 68u on the secondary side of the power converter 68 is electrically connected to a U-phase terminal 70u of the three-phase motor 70. The V-phase terminal 68v on the secondary side of the power converter 68 is electrically connected to a V-phase terminal 70v of the three-phase motor 70. The W-phase terminal 68w on the secondary side of the power converter 68 is electrically connected to a W-phase terminal 70w of the three-phase motor 70. The second end 72b of the shunt resistor 72 is electrically connected to ground GND. A voltmeter 76 is connected in parallel to the shunt resistor 72.

[0022] Three-phase motor 70 includes a U-phase coil 78, a V-phase coil 80, and a W-phase coil 82. A first end of U-phase coil 78 is electrically connected to U-phase terminal 70u. A first end of V-phase coil 80 is electrically connected to V-phase terminal 70v. A first end of W-phase coil 82 is electrically connected to W-phase terminal 70w. Meanwhile, a second end of U-phase coil 78, a second end of V-phase coil 80, and a third end of W-phase coil 82 are electrically connected to one another at neutral point 84.

[0023] The connection circuit 74 includes a resistor 88 and a switch 90 provided on a wiring 86. One end of the wiring 86 is connected to the neutral point 84, and the other end of the wiring 86 is connected to ground GND. A first end of the resistor 88 is electrically connected to the neutral point 84. A second end of the resistor 88 is electrically connected to a first end of the switch 90. A second end of the switch 90 is electrically connected to ground GND.

[0024] At least the resistor 88 of the connection circuit 74 is disposed inside the oil chamber 60 in a manner that allows heat transfer to the oil in the oil chamber 60. The resistor 88 may be a variable resistor or a fixed resistor. On the other hand, the switch 90 of the connection circuit 74 is disposed outside the oil chamber 60.

[0025] The casing 70c of the three-phase motor 70 and the oil chamber 60 are integrated together. This allows heat to be easily transferred from the three-phase motor 70 to the oil stored in the oil chamber 60. The power conversion device 68 may also be in close contact with the oil chamber 60. This allows heat to be easily transferred from the power conversion device 68 to the oil stored in the oil chamber 60.

[0026] Returning to Fig. 2, the description of the lubrication system 28 continues. The control device 34 includes a calculation unit 92 and a storage unit 94. The control device 34 may be configured by, for example, an ECU (Electronic Control Unit).

[0027] The calculation unit 92 may be configured by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the calculation unit 92 may be configured by processing circuitry. At least a part of the calculation unit 92 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). At least a part of the calculation unit 92 may be realized by an electronic circuit including discrete devices.

[0028] The calculation unit 92 includes a control unit 96. The control unit 96 can be realized by the calculation unit 92 executing a program stored in the memory unit 94. The control unit 96 can control the rotation of the three-phase motor 70 by controlling the multiple switching elements 69H and multiple switching elements 69L provided in the power conversion device 68. The control unit 96 can also perform temperature rise control by controlling the multiple switching elements 69H and multiple switching elements 69L and the switch 90 provided in the power conversion device 68. The temperature rise control is control that raises the temperature of the oil using heat generated from the coils (U-phase coil 78, V-phase coil 80, W-phase coil 82) of the three-phase motor 70 and heat generated from the resistor 88.

[0029] The storage unit 94 is a computer-readable storage medium. The storage unit 94 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). The volatile memory is, for example, a random access memory (RAM). The non-volatile memory is, for example, a read-only memory (ROM), a flash memory, etc. Data, etc. are stored in, for example, the volatile memory. Programs, tables, maps, etc. are stored in, for example, the non-volatile memory. At least a portion of the storage unit 94 may be provided in the above-mentioned processor, integrated circuit, etc.

[0030] [3 Oil flow in lubrication circuit 30] 2 lubricates the generator 24 by supplying oil to and recovering oil from the generator 24. Oil is supplied to the generator 24 while the generator 24 is generating electricity.

[0031] When the control unit 96 controls the rotation of the three-phase motor 70, power is supplied from the power supply 66 to the three-phase motor 70, driving the three-phase motor 70. When the three-phase motor 70 is driven, the first pump 38 and the second pump 46 are driven.

[0032] The first pump 38 draws oil from the tank 36 via a flow path 40 and supplies the oil to the generator 24 via a flow path 42. The second pump 46 collects (draws) oil from the generator 24 via a flow path 48 and discharges the oil to the tank 36 via a flow path 50.

[0033] When the oil is at a low temperature, the viscosity of the oil is high. When the oil viscosity is high, the pressure loss of the oil in the generator 24 increases, and the pressure value in the flow path 42 increases. When the pressure value in the flow path 42 exceeds the opening pressure value of the relief valve 54, the relief valve 54 opens. As a result, a portion of the oil discharged from the first pump 38 to the flow path 42 flows through the flow path 56, the relief valve 54, the flow path 58, the oil chamber 60, and the flow path 62, and returns to the tank 36.

[0034] When the relief valve 54 is open, only a small amount of oil is supplied to the generator 24. It is preferable to supply sufficient oil to the generator 24 to lubricate the generator 24. By increasing the oil temperature and reducing the viscosity of the oil, the oil can flow more easily to the generator 24.

[0035] [4. Effects of the Power Unit 32] When power is supplied to the three-phase motor 70, the coils (U-phase coil 78, V-phase coil 80, W-phase coil 82) included in the three-phase motor 70 generate heat. Furthermore, when current is applied to the resistor 88, the resistor 88 generates heat. The lubrication system 28 of this embodiment uses the three-phase motor 70 and the resistor 88 as a heating source for raising the temperature of the oil. The power unit 32 of this embodiment can increase the amount of heat generated by the coils. Below, the reason why the power unit 32 increases the amount of heat generated by the coils will be explained by comparing the power unit 32 of this embodiment with a conventional power unit 132.

[0036] Fig. 4 is a diagram showing current paths in a power unit 132 of a comparative example. Fig. 5 is a diagram showing current paths in the power unit 32 of this embodiment. In the power unit 132 shown in Fig. 4, the same components as those in the power unit 32 shown in Fig. 5 are designated by the same reference numerals. The circuit configuration of the power unit 132 shown in Fig. 4 is the same as the circuit configuration of the power unit 32 shown in Figs. 3 and 5, except that the connection circuit 74 is not provided.

[0037] 4, when one high-side switching element 69H and one low-side switching element 69L of the power conversion device 68 are turned on, a current flows through the coils of the three-phase motor 70. For example, as shown in FIG. 4, a current flows through the U-phase coil 78 and the V-phase coil 80.

[0038] 5, when one switching element 69H on the high side of the power conversion device 68 and a switch 90 are turned on, a current flows through the coils of the three-phase motor 70. For example, as shown in FIG. 5, a current flows through the U-phase coil 78 and the resistor 88.

[0039] Here, the amount of heat generated will be explained using specific numerical values. For example, the voltage value of the power supply 66 is 140 V. The resistance value of each coil of the three-phase motor 70 is 10 Ω. The resistance value of the resistor 88 is 1 Ω. Note that these numerical values ​​are used for the purpose of explanation and do not limit the numerical values ​​of the power unit 32.

[0040] In the power unit 132 shown in FIG. 4, the value I1 of the current flowing through the U-phase coil 78 and the V-phase coil 80 and the heat generation amount W1 of the three-phase motor 70 are as follows. I1=V / R=140 / (10+10)=7A W1=R×I1^2=(10+10)×7^2=980W

[0041] On the other hand, in the power unit 32 shown in FIG. 5, the value I2 of the current flowing through the U-phase coil 78 and the resistor 88 and the heat generation amount W2 of the three-phase motor 70 are as follows. I2=V / R=140 / (10+1)=12.7A W2=R×I2^2=10×12.7^2=1613W

[0042] As described above, the power unit 32 shown in Fig. 5 can generate more heat from the three-phase motor 70 than the power unit 132 shown in Fig. 4. Furthermore, the power unit 32 shown in Fig. 5 can generate heat by the resistor 88.

[0043] In the power unit 32, the casing 70c of the three-phase motor 70 and the oil chamber 60 are integrated, so the heat generated by the three-phase motor 70 is efficiently transferred to the oil stored in the oil chamber 60. Also, in the power unit 32, the resistor 88 is disposed inside the oil chamber 60, so the heat generated by the resistor 88 is efficiently transferred to the oil stored in the oil chamber 60. As a result, the power unit 32 shown in FIG. 5 can heat the oil more quickly and efficiently.

[0044] [5 Power supply determination process] 6 is a flowchart of the energization determination process performed by the control unit 96. When it is necessary to supply oil to the generator 24, the control unit 96 controls the multiple switching elements 69H and multiple switching elements 69L of the power conversion device 68 to drive the three-phase motor 70. This drives the first pump 38 and the second pump 46, and oil circulates through the lubrication circuit 30. Furthermore, the control unit 96 performs the energization determination process shown in FIG. 6. At the start of the energization determination process, the switch 90 is turned off.

[0045] In step S1, the control unit 96 determines whether the load on the three-phase motor 70 is large. Here, the control unit 96 determines that the load on the three-phase motor 70 is large when a physical quantity correlated with the load on the three-phase motor 70 exceeds a predetermined threshold. On the other hand, the control unit 96 determines that the load on the three-phase motor 70 is not large when the physical quantity correlated with the load on the three-phase motor 70 is equal to or smaller than the predetermined threshold.

[0046] The physical quantity correlated with the load on the three-phase motor 70 may be, for example, the value of the current flowing through the three-phase motor 70, or the value of the torque generated on the rotating shaft of the three-phase motor 70. The value of the current flowing through the three-phase motor 70 can be calculated from the voltage value detected by the voltmeter 76 and the resistance value of the shunt resistor 72. Meanwhile, the value of the torque generated on the rotating shaft of the three-phase motor 70 can be detected by a torque sensor (not shown). Predetermined threshold values ​​(current threshold value, torque threshold value) of the physical quantity correlated with the load on the three-phase motor 70 are stored in advance in the storage unit 94.

[0047] The load on the three-phase motor 70 may be determined based on the temperature of the oil. For example, a temperature sensor (not shown) disposed in the flow path 42 may detect the temperature of the oil discharged from the first pump 38. In this case, the control unit 96 may determine that the load on the three-phase motor 70 is large when the detected temperature is below a temperature threshold, and may determine that the load on the three-phase motor 70 is small when the detected temperature is equal to or greater than the temperature threshold.

[0048] If the load on the three-phase motor 70 is heavy (step S1: YES), the process proceeds to step S2. In this case, the oil temperature is relatively low and the oil viscosity is high. On the other hand, if the load on the three-phase motor 70 is not heavy (step S1: NO), the process proceeds to step S4. In this case, the oil temperature is relatively high and the oil viscosity is low.

[0049] When the process proceeds from step S1 to step S2, the control unit 96 performs temperature increase control. For example, the control unit 96 turns on one switching element 69H on the high side of the power conversion device 68 and the switch 90 of the connection circuit 74 so that current flows through one coil (e.g., the U-phase coil 78) of the three-phase motor 70 and the resistor 88, as shown in FIG. 5. As a result, current flows through one coil of the three-phase motor 70 and the resistor 88, as shown in FIG. 5. In this case, the three-phase motor 70 is not driven. After step S2 is executed, the process proceeds to step S3.

[0050] In step S3, the control unit 96 determines whether a predetermined time has elapsed since the temperature increase control was started in step S2. The control unit 96 does not monitor the oil temperature. Therefore, in this embodiment, the control unit 96 performs the temperature increase control for a predetermined time. If the predetermined time has elapsed (step S3: YES), the process proceeds to step S4. On the other hand, if the predetermined time has not elapsed (step S3: NO), the determination in step S3 continues. As a result, the control unit 96 continues the temperature increase control.

[0051] When the process proceeds from step S1 or step S3 to step S4, the control unit 96 controls the rotation of the three-phase motor 70. For example, the control unit 96 controls the switching of each of the switching elements 69H and each of the switching elements 69L of the power conversion device 68 so that the three-phase motor 70 is driven. As a result, current flows through two coils of the three-phase motor 70. In this case, the control unit 96 controls the switch 90 of the connection circuit 74 to open.

[0052] FIG. 7 is a diagram showing changes in oil temperature over time. In FIG. 7, the period indicated by P1 is the period during which temperature rise control is performed. In FIG. 7, the period indicated by P2 is the period during which rotation control of the three-phase motor 70 is performed. According to this embodiment, as shown in FIG. 7, temperature rise control and rotation control are performed as appropriate. The oil temperature rises toward a high temperature range equal to or higher than the temperature threshold. Furthermore, the oil temperature repeatedly rises and falls in the high temperature range. The temperature threshold corresponds to the threshold of a physical quantity correlated with the load on the three-phase motor 70. The high temperature range equal to or higher than the temperature threshold is a temperature range in which the load on the three-phase motor 70 is light. On the other hand, the low temperature range below the temperature threshold is a temperature range in which the load on the three-phase motor 70 is heavy.

[0053] [6 Variations] [6-1 First Modification] Fig. 8 is a diagram showing a three-phase motor 70 and a first pump 38 according to a first modified example. As shown in Fig. 8, a casing 70c of the three-phase motor 70 and the first pump 38 may be integrated together. This allows heat generated by the three-phase motor 70 to be efficiently transferred to the oil passing through the first pump 38.

[0054] As shown in Fig. 8, the resistor 88 of the connection circuit 74 may be disposed in the first pump 38. In this case, heat generated by the resistor 88 is efficiently transferred to the oil passing through the first pump 38. This allows the oil temperature to be raised more quickly and efficiently in the power unit 32 shown in Fig. 5.

[0055] [6-2 Second Modification] The resistor 88 of the connection circuit 74 may be disposed in the casing 70c of the three-phase motor 70. In this case, heat generated by the resistor 88 is transferred to the first pump 38 via the casing 70c of the three-phase motor 70. This allows the oil temperature to be increased more quickly and efficiently.

[0056] [6-3 Third Modification] FIG. 9 is a schematic diagram of a lubrication system 28 of a third modified example. The outlet 60o of the oil chamber 60 may be connected to the flow path 40 via a flow path 62. When the oil in the oil chamber 60 is returned to the tank 36 as in the embodiment shown in FIG. 2, the temperature of the oil heated in the oil chamber 60 drops in the tank 36. In contrast, by returning the oil in the oil chamber 60 to the flow path 40 without passing through the tank 36 as in the third modified example shown in FIG. 9, it is possible to suppress a drop in the temperature of the oil heated in the oil chamber 60. According to the third modified example, the temperature of the oil can be raised in a short period of time.

[0057] [7 Notes] The following additional notes are further disclosed regarding the above embodiment.

[0058] (Appendix 1) The lubrication system (28) of the present disclosure includes a three-phase motor (70) that drives a pump (38) that can supply oil to a lubrication object (24) that is lubricated by the oil, a switch (90) provided on a wiring (86) electrically connected to a neutral point (84) of the three-phase motor, and a control unit (96) that can open and close the switch. By closing the switch, the control unit can supply power to at least one of a plurality of coils (78, 80, 82) provided in the three-phase motor and perform temperature control to raise the temperature of the oil using heat generated from the coil.

[0059] According to this embodiment, the amount of heat generated by the three-phase motor can be increased. By transferring the heat generated by the three-phase motor to the oil, the temperature of the oil can be increased more quickly.

[0060] (Appendix 2) The lubrication system according to Supplementary Note 1 may further include a resistor (88) provided on the wiring, and power may be further supplied to the resistor during the temperature rise control.

[0061] According to this embodiment, the three-phase motor generates heat, and the resistor also generates heat. By transferring the heat generated by the resistor to the oil, the temperature of the oil can be increased more quickly.

[0062] (Appendix 3) In the lubrication system described in Supplementary Note 1, the control unit may perform the temperature increase control when a physical quantity correlated with a load on the three-phase motor exceeds a predetermined threshold value.

[0063] According to this embodiment, temperature increase control is performed when the oil temperature needs to be increased, and normal control of the three-phase motor can be performed when the oil temperature does not need to be increased.

[0064] (Appendix 4) In the lubrication system described in Supplementary Note 1, a casing (70c) of the three-phase motor and the pump may be integrated.

[0065] According to this embodiment, the casing of the three-phase motor and the pump are integrated, so that heat generated by the three-phase motor is efficiently transferred to the oil passing through the pump.

[0066] (Appendix 5) The lubrication system according to Supplementary Note 2 may further include an oil reservoir (60) for storing the oil, and the resistor may be disposed in the oil reservoir.

[0067] According to this embodiment, since the resistor is disposed inside the oil reservoir, heat generated by the resistor is efficiently transferred to the oil stored inside the oil reservoir.

[0068] (Appendix 6) In the lubrication system described in Supplementary Note 5, a casing of the three-phase motor and the oil reservoir may be integrated.

[0069] (Appendix 7) The lubrication system described in Supplementary Note 5 or 6 may include a first flow path (40) connecting a tank (36) that stores the oil and a suction port (38i) of the pump, a second flow path (42) connecting a discharge port (38d) of the pump and the object to be lubricated, and a third flow path (56, 58, 62) connecting the second flow path and the tank or the first flow path via a relief valve (54), and the oil reservoir may be disposed in the third flow path.

[0070] (Appendix 8) The lubrication system described in Appendix 4 may further include a resistor provided on the wiring, and the resistor may be disposed in the pump.

[0071] According to this embodiment, the casing of the three-phase motor and the oil reservoir are integrated, so that heat generated by the three-phase motor is efficiently transferred to the oil stored inside the oil reservoir.

[0072] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments. [Explanation of symbols]

[0073] 24...Generator (lubrication target) 28...Lubrication system 36...Tank 38...First pump (pump) 38d...Discharge port 38i...Suction port 40...flow path (first flow path) 42...flow path (second flow path) 54...Relief valve 56, 58, 62...Flow path (third flow path) 60...Oil chamber (oil storage section) 70...Three-phase motor 70c...Casing 78...U-phase coil (coil) 80...V-phase coil (coil) 82...W-phase coil (coil) 84...Neutral point 86...Wiring 88...Resistor 90...Switch 96...Control unit

Claims

1. a three-phase motor that drives a pump that can supply oil to an object that is lubricated by the oil; a switch provided on a wiring electrically connected to a neutral point of the three-phase motor; a control unit that can open and close the switch; Equipped with The control unit can perform temperature control by closing the switch to supply power to at least one of a plurality of coils provided in the three-phase motor and raising the temperature of the oil using heat emitted from the coils.

2. 10. The lubrication system of claim 1, Further comprising a resistor provided on the wiring, In the temperature rise control, power is further supplied to the resistor.

3. 10. The lubrication system of claim 1, The control unit performs the temperature increase control when a physical quantity correlated with a load of the three-phase motor exceeds a predetermined threshold.

4. 10. The lubrication system of claim 1, A lubrication system in which the casing of the three-phase motor and the pump are integrated.

5. 3. The lubrication system of claim 2, Further provided is an oil reservoir that stores the oil, The resistor is disposed within the oil reservoir.

6. 6. The lubrication system of claim 5, A lubrication system in which the casing of the three-phase motor and the oil reservoir are integrated.

7. 7. The lubrication system according to claim 5 or 6, a first flow path connecting a tank that stores the oil and a suction port of the pump; a second flow path connecting a discharge port of the pump and the object to be lubricated; a third flow path connecting the second flow path to the tank or the first flow path via a relief valve; Preparation, The oil reservoir is disposed in the third flow path.

8. 5. The lubrication system of claim 4, Further comprising a resistor provided on the wiring, The resistor is disposed in the pump.

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