Power system and control method for the same

Abstract

To provide a better power system and a control method for the same.SOLUTION: A power system 10 includes: a power device 12; a supply pump 34 for supplying liquid oil for lubricating the power device; a supply flow path 36 for guiding the oil supplied from the supply pump to the power device; a recovery pump 55 for recovering the oil distributed in the power device; a recovery flow path 53 for guiding the oil distributed in the power device to the recovery pump; a circulation flow path 56 for guiding the oil recovered by the recovery pump to the supply pump; a bypass flow path 62 connecting the supply flow path to the recovery flow path; and an on-off valve 64 for opening / closing the bypass flow path.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power system and a method for controlling a power system. [Background technology]

[0002] In recent years, technological developments have been underway in power systems that contribute to energy efficiency in order to ensure that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Patent Document 1 discloses a power system that lubricates bearings of a power device by supplying liquid oil sent from a supply pump to the bearings. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-25331 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need for better power systems and methods of controlling power systems.

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

[0007] A first aspect of the present disclosure is a power system comprising: a power unit; a supply pump for supplying liquid oil to lubricate the power unit; a supply flow path that guides the oil sent from the supply pump to the power unit; a recovery pump for recovering the oil that has circulated through the power unit; a recovery flow path that guides the oil that has circulated through the power unit to the recovery pump; a circulation flow path that guides the oil recovered by the recovery pump to the supply pump; a bypass flow path that connects the supply flow path and the recovery flow path; and an on-off valve that opens and closes the bypass flow path.

[0008] A second aspect of the present disclosure is a control method for a power system, the power system comprising: a power unit; a supply pump for supplying liquid oil to lubricate the power unit; a supply flow path that guides the oil supplied from the supply pump to the power unit; a recovery pump for recovering the oil that has circulated through the power unit; a recovery flow path that guides the oil that has circulated through the power unit to the recovery pump; a circulation flow path that guides the oil recovered by the recovery pump to the supply pump; a bypass flow path connecting the supply flow path and the circulation flow path; an on-off valve that opens and closes the bypass flow path; a motor for driving the supply pump and the recovery pump; and a motor control unit that controls the motor, and when the on-off valve is in an open state, the motor control unit controls the motor to set the torque of the motor to a predetermined target torque. [Effects of the Invention]

[0009] According to the present disclosure, a better power system and a method for controlling the power system can be provided. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a power system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of the control device for the power system. [Figure 3]FIG. 3 is a flowchart showing a control method for a power system according to an embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram for explaining the flow of oil in the power system. [Figure 5] FIG. 5 is a schematic diagram for explaining the flow of oil in the power system. [Figure 6] FIG. 6 is a schematic diagram of a power system according to a comparative example. [Figure 7] FIG. 7 is a timing chart illustrating a method for controlling the power system. DETAILED DESCRIPTION OF THE INVENTION

[0011] When starting a power system in a low-temperature environment (e.g., an environment below freezing point), the pressure of the oil circulating inside the power unit may become excessively high due to the relatively high viscosity of the oil. Therefore, in a low-temperature environment, it is necessary to supply the oil to the power unit after raising the temperature of the oil to reduce its viscosity. However, providing a heating device for raising the temperature of the oil in the power system increases the manufacturing cost and weight of the power system. The present disclosure has been made in consideration of these issues and provides a power system and a control method for the power system that can prevent the pressure of the oil circulating inside the power unit from becoming excessively high and can efficiently raise the temperature of the oil while suppressing increases in manufacturing cost and weight.

[0012] FIG. 1 is a schematic diagram of a power system 10 according to an embodiment of the present invention. The power system 10 is mounted on, for example, an aircraft. The aircraft is, for example, an electric vertical take-off and landing aircraft (eVTOL). Note that the aircraft is not limited to an electric vertical take-off and landing aircraft. Furthermore, the power system 10 is not limited to being mounted on an aircraft, and may be mounted on a ship, vehicle, etc. The power system 10 may also be provided on a stationary power generation device.

[0013] 1, the power system 10 includes a power plant 12, an oil supply device 14, and an oil recovery device 16. The power plant 12 has a rotating electric machine 18 and a gas turbine engine 20. The rotating electric machine 18 may, for example, drive a VTOL rotor (not shown) of an electric vertical take-off and landing aircraft.

[0014] The rotating electric machine 18 has a rotating electric machine main body 22, a bearing portion 24, a partition member 26, and a casing 28. The rotating electric machine main body 22 includes a rotor 30 and a stator 32. The rotor 30 has a rotating shaft 30a and a magnet portion 30b provided on the outer periphery of the rotating shaft 30a. The rotating shaft 30a is connected to, for example, the shaft portion 20a of the gas turbine engine 20. The magnet portion 30b is, for example, a permanent magnet. The stator 32 is formed in an annular shape. The rotor 30 is inserted into a hole in the interior of the stator 32. The stator 32 has an electromagnetic coil 32a and a stator core 32b. The rotor 30 and the stator 32 are not limited to the configurations described above.

[0015] For example, when starting to drive the gas turbine engine 20, the rotating electric machine 18 functions as a motor 66 that rotates the shaft portion 20a of the gas turbine engine 20 by supplying an alternating current to the electromagnetic coil 32a of the stator 32 to rotate the rotor 30. The rotating electric machine 18 also functions as a generator that generates electricity when the rotor 30 is rotated by the driving force of the gas turbine engine 20. In the rotating electric machine 18, the rotor 30 and the stator 32 generate heat. Specifically, in the rotating electric machine 18, the magnet portion 30b of the rotor 30 and the electromagnetic coil 32a of the stator 32 are particularly likely to become hot.

[0016] The bearing portion 24 has a first bearing 24a and a second bearing 24b. The first bearing 24a rotatably supports one end of the rotating shaft 30a. The second bearing 24b rotatably supports the other end of the rotating shaft 30a. Each of the first bearing 24a and the second bearing 24b is, for example, a rolling bearing. Each of the first bearing 24a and the second bearing 24b may also be a plain bearing.

[0017] The partition member 26 is formed in a cylindrical shape. The rotor 30 is disposed inside the partition member 26, and the stator 32 is disposed outside the partition member 26. The partition member 26 is made of, for example, a ceramic material. The partition member 26 can be fixed to a casing 28. The partition member 26 separates the space in which the rotor 30 is disposed from the space in which the stator 32 is disposed in a liquid-tight and airtight manner. The casing 28 houses the rotating electric machine main body 22 and the bearing portion 24.

[0018] The oil supply device 14 supplies liquid oil to the rotating electrical machine 18 (power unit 12). Examples of oil include gas turbine oil. The oil cools the heat-generating parts (rotor 30 and stator 32) of the rotating electrical machine 18 and lubricates the bearings 24. The oil supply device 14 has a supply pump 34 and a supply flow path 36. The supply flow path 36 guides the oil sent from the supply pump 34 to the rotating electrical machine 18.

[0019] The rotating electric machine 18 is provided with a rotor cooling passage 38, a stator cooling passage 40, a lubrication passage 42, a storage section 46, a first discharge passage 48, a second discharge passage 50, and a third discharge passage 52.

[0020] The oil introduced from the supply passage 36 flows separately through the rotor cooling passage 38, the stator cooling passage 40, and the lubrication passage 42. In other words, the rotor cooling passage 38, the stator cooling passage 40, and the lubrication passage 42 are arranged in parallel. The rotor cooling passage 38 and the stator cooling passage 40 are isolated by the partition member 26. Therefore, the oil flowing through the rotor cooling passage 38 and the oil flowing through the stator cooling passage 40 do not mix along the way.

[0021] The rotor cooling flow passage 38 circulates the oil introduced from the supply flow passage 36 through the rotor 30. The rotor cooling flow passage 38 includes a flow passage formed inside the rotor 30. In this case, the rotor 30 can be efficiently cooled by the oil flowing inside the rotor 30. The rotor cooling flow passage 38 is a flow passage open to the atmosphere. Therefore, gas (air) is mixed with the oil flowing through the rotor cooling flow passage 38.

[0022] The stator cooling flow path 40 circulates the oil introduced from the supply flow path 36 to the stator 32. The stator cooling flow path 40 is formed to surround the stator 32. In this case, the oil can come into contact with the electromagnetic coil 32a of the stator 32, so the stator 32 can be cooled efficiently. The stator cooling flow path 40 is a flow path that is not open to the atmosphere. Therefore, gas (air) does not mix with the oil flowing through the stator cooling flow path 40.

[0023] The lubrication passage 42 includes a first lubrication passage 42a and a second lubrication passage 42b. The first lubrication passage 42a supplies the oil guided from the supply passage 36 to the first bearing 24a. The oil that has flowed through the first lubrication passage 42a is sprayed onto the first bearing 24a by the pressure of the supply pump 34. Gas (air) is mixed with the oil sprayed from the first lubrication passage 42a onto the first bearing 24a. The second lubrication passage 42b supplies the oil guided from the supply passage 36 to the second bearing 24b. The oil that has flowed through the second lubrication passage 42b is sprayed onto the second bearing 24b by the pressure of the supply pump 34. Gas (air) is mixed with the oil sprayed from the second lubrication passage 42b onto the second bearing 24b.

[0024] The storage section 46 is formed, for example, in the bottom of the casing 28. The storage section 46 includes a first storage section 46a and a second storage section 46b. The first storage section 46a is located, for example, below the first bearing 24a (in the direction of gravity). The second storage section 46b is located, for example, below the second bearing 24b (in the direction of gravity). The size, shape, position, etc. of the storage section 46 can be set as appropriate.

[0025] The first discharge flow path 48 guides the oil that has flowed through the first bearing 24a to the first reservoir 46a. The second discharge flow path 50 guides the oil that has flowed through the second bearing 24b to the second reservoir 46b. The third discharge flow path 52 guides the oil that has flowed through the rotor cooling flow path 38 to the second reservoir 46b. The oil flowing through the first discharge flow path 48, the second discharge flow path 50, and the third discharge flow path 52 is mixed with gas (air). In other words, the reservoir 46 stores a gas-liquid mixed fluid that is a mixture of liquid oil and gaseous air.

[0026] The oil recovery device 16 has a recovery passage 53, a discharge passage 54, a recovery pump 55, a circulation passage 56, a gas-liquid separator 58, and a tank 60. The recovery passage 53 is connected to the first reservoir 46a, the second reservoir 46b, and the recovery pump 55. The recovery passage 53 is connected to the stator cooling passage 40 via the discharge passage 54. That is, the oil that has flowed through the stator cooling passage 40 merges with the gas-liquid mixed fluid flowing through the recovery passage 53 via the discharge passage 54.

[0027] The recovery pump 55 recovers the gas-liquid mixture fluid stored in the first storage section 46a and the second storage section 46b. The capacity of the recovery pump 55 is larger than the capacity of the supply pump 34. In other words, the maximum amount of oil discharged per unit time by the recovery pump 55 is larger than the maximum amount of oil discharged per unit time by the supply pump 34.

[0028] The circulation flow path 56 guides the oil recovered by the recovery pump 55 to the supply pump 34. The circulation flow path 56 is provided with a gas-liquid separator 58 and a tank 60. The gas-liquid separator 58 separates gas from the gas-liquid mixed fluid sent by the recovery pump 55. The liquid oil from which the gas has been separated by the gas-liquid separator 58 is stored in the tank 60.

[0029] The power system 10 further includes a bypass flow path 62, a relief valve (on-off valve) 64, one motor 66, and a power transmission mechanism 68. The bypass flow path 62 connects the supply flow path 36 and the recovery flow path 53. The relief valve 64 opens and closes the bypass flow path 62. When the pressure of the oil supplied from the supply pump 34 reaches a predetermined upper pressure limit, a valve element (not shown) of the relief valve 64 is pushed by the oil and opens. In other words, the relief valve 64 closes the bypass flow path 62 when the pressure of the oil supplied from the supply pump 34 (the discharge pressure of the supply pump 34) is lower than the upper pressure limit.

[0030] The motor 66 drives the supply pump 34 and the recovery pump 55. The power transmission mechanism 68 transmits the rotational driving force of the motor 66 to the supply pump 34 and the recovery pump 55. In this embodiment, the power transmission mechanism 68 has a first mechanism 68a that transmits the rotational driving force of the motor 66 to the recovery pump 55, and a second mechanism 68b that transmits the rotational driving force transmitted from the motor 66 to the recovery pump 55 to the supply pump 34. The power transmission mechanism 68 may include, for example, a speed reduction mechanism. The configuration of the power transmission mechanism 68 can be set as appropriate.

[0031] FIG. 2 is a block diagram of a control device 72 of the power system 10. As shown in FIG. 2, the power system 10 further includes a sensor 70 and a control device 72. The sensor 70 detects various types of information about the power system 10. Detection signals from the sensor 70 are sequentially transmitted to the control device 72. The sensor 70 includes, for example, a temperature sensor. In this case, the temperature sensor detects, for example, the temperature of the oil flowing through the portion of the supply flow path 36 between the supply pump 34 and the relief valve 64. The sensor 70 may include a pressure sensor that detects the pressure of the oil (the discharge pressure of the supply pump 34), a torque sensor that detects the torque of the motor 66, a pump rotation speed sensor that detects the rotation speed of each of the supply pump 34 and the recovery pump 55, an engine rotation speed sensor that detects the rotation speed of the gas turbine engine 20, and the like.

[0032] The control device 72 includes a calculation unit 74 and a storage unit 76. The calculation unit 74 is configured by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). In other words, the calculation unit 74 is configured by processing circuitry.

[0033] The calculation unit 74 has a control unit 78, a motor control unit 80, an information acquisition unit 82, and a determination unit 84. The control unit 78, the motor control unit 80, the information acquisition unit 82, and the determination unit 84 can be realized by the calculation unit 74 executing a program stored in the storage unit 76.

[0034] At least a portion of the control unit 78, motor control unit 80, information acquisition unit 82, and determination unit 84 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).Also, at least a portion of the control unit 78, motor control unit 80, information acquisition unit 82, and determination unit 84 may be configured by an electronic circuit including discrete devices.

[0035] The storage unit 76 is composed of a volatile memory (not shown) and a non-volatile memory (not shown). Examples of the volatile memory include RAM (Random Access Memory). The volatile memory is used as a working memory for the processor and temporarily stores data necessary for processing or calculation. Examples of the non-volatile memory include ROM (Read Only Memory) and flash memory. The non-volatile memory is used as a storage memory and stores programs, tables, maps, etc. At least a part of the storage unit 76 may be provided in the processor, integrated circuit, etc. described above.

[0036] The control unit 78 is responsible for overall control of the power system 10. The motor control unit 80 controls the motor 66. The information acquisition unit 82 acquires various information based on detection signals sent from the sensor 70 to the control device 72. Examples of the various information include the oil temperature, the oil pressure (the discharge pressure of the supply pump 34), the torque of the motor 66, the rotation speed of the supply pump 34, the rotation speed of the recovery pump 55, and the rotation speed of the gas turbine engine 20. The determination unit 84 determines whether the relief valve 64 is in a closed state based on the information acquired by the information acquisition unit 82.

[0037] Next, a control method for the power system 10 will be described. Specifically, a control method for the power system 10 when starting up the power system 10 in a low-temperature environment (for example, an environment below the freezing point) will be described. Fig. 3 is a flowchart showing a control method for the power system 10 according to an embodiment of the present invention.

[0038] As shown in FIG. 3, in step S1, the control unit 78 starts the power system 10. Specifically, the motor control unit 80 controls the motor 66 to drive each of the supply pump 34 and the recovery pump 55. When the supply pump 34 is driven, oil stored in the tank 60 is sent from the supply pump 34 to the supply flow path 36. In a low-temperature environment, the temperature of the oil is low (its viscosity is high), so the pressure of the oil sent from the supply pump 34 becomes higher than the upper pressure limit value. Therefore, the oil sent from the supply pump 34 to the supply flow path 36 opens the relief valve 64.

[0039] FIG. 4 is a schematic diagram illustrating the flow of oil in the power system 10. Specifically, FIG. 4 is an explanatory diagram illustrating the flow of oil when the relief valve 64 is open. As shown in FIG. 4, when the relief valve 64 is open, most of the oil is guided to the recovery flow path 53 via the bypass flow path 62. The oil guided to the recovery flow path 53 is returned to the supply pump 34 via the circulation flow path 56 (gas-liquid separator 58 and tank 60) by the recovery pump 55. That is, most of the oil discharged from the supply pump 34 circulates through a path that returns the oil to the supply pump 34 via the supply flow path 36, the bypass flow path 62, the recovery flow path 53, the recovery pump 55, and the circulation flow path 56. In this case, the oil is heated by the supply pump 34 when it flows through the supply pump 34, and is also heated by the recovery pump 55 when it flows through the recovery pump 55. That is, the oil is heated by the supply pump 34 and the recovery pump 55.

[0040] With the relief valve 64 in an open state, a small amount of oil flows into the rotating electrical machine 18. The oil that flows into the rotating electrical machine 18 is divided into the rotor cooling passage 38, the stator cooling passage 40, and the lubrication passage 42, and then recovered by the recovery pump 55 via the recovery passage 53. Because the amount of oil flowing inside the rotating electrical machine 18 is relatively small, the oil does not apply excessive force to the components of the rotating electrical machine 18.

[0041] The control unit 78 also starts the gas turbine engine 20 to rotate the shaft 20a of the gas turbine engine 20 at a predetermined idle speed. This causes the rotor 30 and the stator 32 to generate heat, thereby raising the temperature of the oil flowing through the rotating electrical machine 18. After starting the power system 10, the process proceeds to step S2.

[0042] In step S2, the information acquisition unit 82 acquires various pieces of information. Specifically, the information acquisition unit 82 acquires various pieces of information based on the detection signal transmitted from the sensor 70 to the control device 72. After that, the process proceeds to step S3.

[0043] In step S3, the determination unit 84 determines whether the relief valve 64 is in the closed state. Specifically, for example, the determination unit 84 determines that the relief valve 64 is in the closed state when the oil temperature is equal to or higher than a predetermined target temperature. The target temperature is set based on the upper pressure limit value of the relief valve 64. The viscosity of oil increases as the temperature decreases. Therefore, the pressure of the oil supplied from the supply pump 34 increases as the temperature decreases (as the viscosity increases). In other words, there is a correlation between the oil temperature and the oil pressure. In this embodiment, the target temperature is set to the oil temperature when the relief valve 64 switches from the open state to the closed state. The oil temperature is acquired by the information acquisition unit 82.

[0044] If the determination unit 84 determines that the relief valve 64 is not in a closed state (is in an open state) (NO in step S3), the process proceeds to step S4.

[0045] In step S4, the motor control unit 80 performs constant torque control. Specifically, the motor control unit 80 controls the motor 66 to set the torque of the motor 66 to a predetermined target torque. Then, the process proceeds to step S5.

[0046] In step S5, the determination unit 84 determines whether the control unit 78 has received a stop signal for the power system 10. The control unit 78 receives the stop signal for the power system 10, for example, when a user operates the stop switch for the power system 10. If the determination unit 84 determines that the control unit 78 has not received a stop signal for the power system 10 (NO in step S5), the process proceeds to step S2.

[0047] In step S3, if the determination unit 84 determines that the relief valve 64 is in a closed state (YES in step S3), the process proceeds to step S6.

[0048] FIG. 5 is a schematic diagram illustrating the flow of oil in the power system 10. Specifically, FIG. 5 is an explanatory diagram illustrating the flow of oil when the relief valve 64 is closed. As shown in FIG. 5, when the relief valve 64 is closed, the oil does not flow into the bypass flow path 62. In other words, all of the oil sent from the supply pump 34 to the supply flow path 36 flows to the rotating electric machine 18. The oil flowing to the rotating electric machine 18 is divided and flows into the rotor cooling flow path 38, the stator cooling flow path 40, and the lubrication flow path 42. After cooling the rotor 30, the oil flowing through the rotor cooling flow path 38 is guided to the second reservoir 46b via the third discharge flow path 52 by the centrifugal force and gravity generated by the rotation of the rotor 30. The oil flowing through the third discharge flow path 52 contains gas (air). In other words, the oil flowing through the third discharge flow path 52 is a gas-liquid mixed fluid.

[0049] The oil flowing through the stator cooling passage 40 cools the stator 32 and is then led to the recovery passage 53 via the outlet passage 54 .

[0050] The oil flowing through the first lubrication flow path 42a is sprayed onto the first bearing 24a by the pressure of the supply pump 34. As a result, the first bearing 24a is lubricated by the oil. The oil that has flowed through the first bearing 24a flows down into the first reservoir 46a via the first discharge flow path 48 by gravity. Gas (air) is mixed into the oil flowing through the first discharge flow path 48. In other words, the oil flowing through the first discharge flow path 48 is a gas-liquid mixed fluid.

[0051] The oil flowing through the second lubrication flow path 42b is sprayed onto the second bearing 24b by the pressure of the supply pump 34. As a result, the second bearing 24b is lubricated by the oil. The oil that has flowed through the second bearing 24b flows down into the second reservoir 46b via the second discharge flow path 50 by gravity. Gas (air) is mixed into the oil flowing through the second discharge flow path 50. In other words, the oil flowing through the second discharge flow path 50 is a gas-liquid mixed fluid.

[0052] The gas-liquid mixture fluid stored in the first storage section 46a and the second storage section 46b is sent to the gas-liquid separator 58 via the recovery passage 53 by the recovery pump 55. The gas-liquid mixture fluid sent to the gas-liquid separator 58 is separated into oil and gas (air) by the gas-liquid separator 58. The oil from which the gas has been separated by the gas-liquid separator 58 is led to the tank 60.

[0053] In step S6, the motor control unit 80 performs constant rotation speed control. Specifically, the motor control unit 80 controls the motor 66 to set the rotation speed of the supply pump 34 to a target rotation speed. The target rotation speed is, for example, determined in advance. The target rotation speed may be set based on the required output of the power unit 12. After this, the process proceeds to step S5.

[0054] In step S5, if determination unit 84 determines that control unit 78 has received a stop signal for power system 10 (YES in step S5), the process proceeds to step S7. In step S7, control unit 78 stops power system 10. Specifically, motor control unit 80 controls motor 66 to stop driving supply pump 34 and recovery pump 55. After this, the process shown in FIG. 3 is completed.

[0055] Fig. 6 is a schematic diagram of a power system 100 according to a comparative example. As shown in Fig. 6, in the power system 100 according to the comparative example, a bypass flow path 62 is connected to a portion of the circulation flow path 56 between the tank 60 and the supply pump 34. Note that the configuration of the power system 100 other than the bypass flow path 62 is the same as the configuration of the power system 10 according to this embodiment.

[0056] In the power system 100 according to the comparative example, when the relief valve 64 is open, most of the oil sent from the supply pump 34 to the supply passage 36 is returned to the supply pump 34 via the bypass passage 62 and the circulation passage 56. In this case, the oil is heated by the single supply pump 34.

[0057] Figure 7 is a timing chart illustrating a control method for the power systems 10 and 100. In Figure 7, the dashed line is a timing chart for the power system 100 according to a comparative example, and the solid line is a timing chart for the power system 10 according to this embodiment.

[0058] 7, in the comparative example, when power system 100 is started at time t0 in a low-temperature environment, relief valve 64 is in the open state, and most of the oil sent from supply pump 34 to supply flow path 36 is returned to supply pump 34 via bypass flow path 62 and circulation flow path 56. In other words, the oil is heated by supply pump 34.

[0059] Furthermore, the motor control unit 80 controls the motor 66 to set the rotation speed of the supply pump 34 to a predetermined rotation speed n1. Therefore, as the oil temperature rises, the viscosity of the oil decreases, causing the torque of the motor 66 to decrease. That is, in the power system 100 according to the comparative example, the rotation speed of the supply pump 34 is maintained at rotation speed n1 even if the viscosity of the oil decreases. That is, in the comparative example, even if the viscosity of the oil decreases, the thermal energy supplied to the oil from the supply pump 34 does not change.

[0060] In the comparative example, at time t0, the control unit 78 controls the power plant 12 to set the rotational speed of the gas turbine engine 20 to a predetermined rotational speed na (idle rotational speed). As a result, the rotor 30 and stator 32 of the rotating electrical machine 18 generate heat, and the small amount of oil introduced from the supply passage 36 to the rotating electrical machine 18 is heated by the rotor 30 and stator 32 of the rotating electrical machine 18. The small amount of heated oil is returned to the supply pump 34 via the recovery passage 53, the recovery pump 55, and the circulation passage 56.

[0061] In the comparative example, the oil temperature reaches temperature T1 (target temperature) at time t2. At time t2, the discharge pressure (oil pressure) of the supply pump 34 becomes lower than pressure P1 (upper pressure limit), and the relief valve 64 is closed. That is, the bypass flow path 62 is blocked by the relief valve 64.

[0062] Furthermore, at time t2, the control unit 78 controls the power plant 12 to set the rotation speed of the gas turbine engine 20 to rotation speed nb (target engine rotation speed). This allows a sufficient amount (stable flow rate) of oil to lubricate the bearings 24 of the rotating electrical machine 18, making it possible to increase the output of the power plant 12.

[0063] In the comparative example, when the relief valve 64 is closed, the motor control unit 80 controls the motor 66 to set the rotation speed of the supply pump 34 to rotation speed n2 (target rotation speed). Then, at time t4, the oil temperature rises to temperature T2, the torque of the motor 66 decreases to torque N2, and the discharge pressure of the supply pump 34 (oil pressure) decreases to pressure P2.

[0064] On the other hand, in the power system 10 according to this embodiment, when the power system 10 is started at time t0 in a low-temperature environment, relief valve 64 is in the open state, and therefore most of the oil sent from the supply pump 34 to the supply flow path 36 is returned to the supply pump 34 via the bypass flow path 62, the recovery flow path 53, the recovery pump 55, and the circulation flow path 56. In other words, the oil is heated by the supply pump 34 and the recovery pump 55.

[0065] Furthermore, the motor control unit 80 controls the motor 66 to set the torque of the motor 66 to a predetermined torque N1 (target torque). Therefore, as the viscosity of the oil decreases, the rotation speeds of the supply pump 34 and the recovery pump 55 increase. In other words, in this embodiment, as the viscosity of the oil decreases, the thermal energy supplied to the oil from the supply pump 34 and the recovery pump 55 can be increased.

[0066] In this embodiment, as in the comparative example, at time t0, the control unit 78 controls the power plant 12 to set the rotational speed of the gas turbine engine 20 to a predetermined rotational speed na (idle rotational speed). As a result, the rotor 30 and stator 32 of the rotating electrical machine 18 generate heat, and the small amount of oil introduced from the supply passage 36 to the rotating electrical machine 18 is heated by the rotor 30 and stator 32 of the rotating electrical machine 18. The heated small amount of oil is returned to the supply pump 34 via the recovery passage 53, the recovery pump 55, and the circulation passage 56.

[0067] In this embodiment, the oil temperature reaches temperature T1 (target temperature) at time t1, which is before time t2. At time t1, the discharge pressure (oil pressure) of the supply pump 34 becomes lower than pressure P1 (upper pressure limit), and the relief valve 64 is closed. That is, the bypass flow path 62 is blocked by the relief valve 64.

[0068] Furthermore, at time t1, the control unit 78 controls the power plant 12 to set the rotation speed of the gas turbine engine 20 to rotation speed nb (target engine rotation speed). This allows a sufficient amount (stable flow rate) of oil to lubricate the bearings 24 of the rotating electrical machine 18, making it possible to increase the output of the power plant 12.

[0069] In this embodiment, when the relief valve 64 is closed, the motor control unit 80 controls the motor 66 to set the rotation speed of the supply pump 34 to rotation speed n2 (target rotation speed). Then, at time t3 before time t4, the oil temperature rises to temperature T2, the torque of the motor 66 decreases to torque N2, and the discharge pressure of the supply pump 34 (oil pressure) decreases to pressure P2.

[0070] According to this embodiment, when the power system 10 is started in a low-temperature environment, the relief valve 64 can be opened, thereby preventing highly viscous oil from being introduced into the rotating electric machine 18. This prevents the pressure of the oil circulating inside the rotating electric machine 18 from becoming excessively high. Furthermore, with the relief valve 64 open, most of the oil sent from the supply pump 34 to the supply flow path 36 can be returned to the supply pump 34 via the bypass flow path 62, the recovery flow path 53, the recovery pump 55, and the circulation flow path 56. This allows the oil to be heated by the supply pump 34 and the recovery pump 55, eliminating the need for an additional heating device such as a heater. This allows the oil to be heated efficiently while suppressing increases in the manufacturing cost and weight of the power system 10. Therefore, a better power system 10 and a manufacturing method for the power system 10 can be provided.

[0071] This embodiment is not limited to the above-described configuration. The determination unit 84 may determine that the relief valve 64 has closed when the discharge pressure (oil pressure) of the supply pump 34 becomes lower than the upper pressure limit. The determination unit 84 may also determine that the relief valve 64 has closed when the rotation speed of the supply pump 34 becomes equal to or higher than the target rotation speed.

[0072] The power system 10 is not limited to using the relief valve 64, which closes when the oil pressure reaches the upper pressure limit, but may use a solenoid valve (on-off valve). In this case, the control device 72 controls the solenoid valve to close the solenoid valve and block the bypass flow path 62 when the oil pressure reaches the upper pressure limit.

[0073] Power system 10 may drive supply pump 34 and recovery pump 55 using the rotational driving force of rotor 30 of rotating electric machine 18. In this case, motor 66 and motor control unit 80 of power system 10 are omitted. Power system 10 may also include a motor for driving supply pump 34 and a motor for driving the recovery pump separately.

[0074] The following additional notes are further disclosed regarding the above embodiment.

[0075] (Appendix 1) A power system (10) of the present disclosure includes a power unit (12), a supply pump (34) for supplying liquid oil for lubricating the power unit, a supply flow path (36) for guiding the oil sent from the supply pump to the power unit, a recovery pump (55) for recovering the oil that has circulated through the power unit, a recovery flow path (53) for guiding the oil that has circulated through the power unit to the recovery pump, a circulation flow path (56) for guiding the oil recovered by the recovery pump to the supply pump, a bypass flow path (62) connecting the supply flow path and the recovery flow path, and an on-off valve (64) for opening and closing the bypass flow path.

[0076] With this configuration, when the power system is started in a low-temperature environment, the on-off valve can be opened, thereby preventing highly viscous oil from being introduced into the power unit. This prevents the pressure of the oil circulating inside the power unit from becoming excessively high. Furthermore, with the on-off valve open, most of the oil sent from the supply pump to the supply flow path can be returned to the supply pump via the bypass flow path, the recovery flow path, the recovery pump, and the circulation flow path. This allows the oil to be heated by the supply pump and the recovery pump, eliminating the need for an additional heating device such as a heater. This allows the oil to be heated efficiently while minimizing increases in the manufacturing cost and weight of the power system. Therefore, a better power system can be provided.

[0077] (Appendix 2) In the power system of claim 1, the recovery pump may have a larger capacity than the supply pump.

[0078] With this configuration, the temperature of the oil can be raised efficiently by the supply pump and the recovery pump.

[0079] (Appendix 3) In the power system described in Appendix 2, the oil discharged from the power unit may be mixed with gas, and a gas-liquid separator (58) that separates the gas from the oil may be provided in the circulation flow path.

[0080] With this configuration, the oil mixed with gas can be smoothly guided to the gas-liquid separator by the recovery pump, which has a larger capacity than the supply pump, and the oil from which gas has been removed by the gas-liquid separator can be returned to the supply pump.

[0081] (Appendix 4) In the power system described in any one of Supplementary Notes 1 to 3, the on-off valve may be a relief valve that is pushed open by the oil supplied from the supply pump when the pressure of the oil reaches a predetermined upper pressure limit.

[0082] According to this configuration, the pressure of the oil circulating inside the power unit can be prevented from becoming excessively high with a simple configuration.

[0083] (Appendix 5) The power system according to any one of Supplementary Notes 1 to 4 may further include a motor (66) for driving the supply pump and the recovery pump.

[0084] With this configuration, the degree of freedom in the layout of the supply pump and the recovery pump can be increased compared to when the supply pump and the recovery pump are driven by power generated by a power unit.

[0085] (Appendix 6) The power system according to Supplementary Note 5 may include a power transmission mechanism (68) that transmits the rotational driving force of the motor to the supply pump and the recovery pump.

[0086] With this configuration, the power system can be made more compact than when a motor for driving the supply pump and a motor for driving the recovery pump are provided separately.

[0087] (Appendix 7) The power system according to Supplementary Note 5 or 6 may further include a motor control unit (80) that controls the motor, and when the on-off valve is in an open state, the motor control unit may control the motor to set the torque of the motor to a predetermined target torque.

[0088] With this configuration, as the oil viscosity decreases with an increase in oil temperature, the thermal energy supplied to the oil from each of the supply pump and the recovery pump can be increased, thereby shortening the time it takes for the oil to heat up.

[0089] (Appendix 8) In the power system described in Supplementary Note 7, when the on-off valve is in a closed state, the motor control unit may control the motor to set the rotation speed of the supply pump to a target rotation speed.

[0090] With this configuration, a stable flow rate of oil can be supplied to the power unit when the on-off valve is in a closed state.

[0091] (Appendix 9) In the power system according to any one of Supplementary Notes 1 to 8, the power unit may include a bearing (24) that rotatably supports a rotor (30), and a lubrication passage (42) that circulates the oil through the bearing.

[0092] With this configuration, the bearing portion can be lubricated by oil.

[0093] (Appendix 10) The power system control method of the present disclosure includes the power system including a power unit, a supply pump for supplying liquid oil to lubricate the power unit, a supply flow path that guides the oil sent from the supply pump to the power unit, a recovery pump for recovering the oil that has circulated through the power unit, a recovery flow path that guides the oil that has circulated through the power unit to the recovery pump, a circulation flow path that guides the oil recovered by the recovery pump to the supply pump, a bypass flow path connecting the supply flow path and the circulation flow path, an on-off valve that opens and closes the bypass flow path, a motor for driving the supply pump and the recovery pump, and a motor control unit that controls the motor, and when the on-off valve is in an open state, the motor control unit controls the motor to set the torque of the motor to a predetermined target torque.

[0094] Such a method may provide a better method of controlling the power system.

[0095] (Appendix 11) In the control method for a power system according to Supplementary Note 10, when the on-off valve is in a closed state, the motor control unit may control the motor to set the rotation speed of the supply pump to a target rotation speed.

[0096] 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]

[0097] 10, 100... Power system 12... Power unit 24...bearing portion 30...rotor 34...Supply pump 36...Supply flow path 42...Lubrication passage 53...Recovery passage 55... Recovery pump 56... Circulation flow path 58...gas-liquid separator 62...bypass flow path 64...Relief valve (on-off valve) 66...Motor 68...power transmission mechanism 78...control section 80...Motor control unit

Claims

1. A power unit; a supply pump for delivering liquid oil for lubricating the power plant; a supply flow path that guides the oil sent from the supply pump to the power unit; a recovery pump for recovering the oil that has circulated through the power unit; a recovery flow path that guides the oil that has circulated in the power unit to the recovery pump; a circulation flow path for guiding the oil recovered by the recovery pump to the supply pump; a bypass flow path connecting the supply flow path and the recovery flow path; an on-off valve that opens and closes the bypass flow path; A power system comprising:

2. 10. The power system of claim 1, A power system wherein the recovery pump has a capacity greater than the capacity of the supply pump.

3. 3. The power system of claim 2, The oil discharged from the power unit is mixed with gas, A power system, wherein the circulation flow path is provided with a gas-liquid separator that separates the gas from the oil.

4. 10. The power system of claim 1, The power system, wherein the on-off valve is a relief valve that opens when pushed by the oil supplied from the supply pump when the pressure of the oil reaches a predetermined upper pressure limit.

5. A power system according to any one of claims 1 to 4, A power system including a motor for driving the supply pump and the return pump.

6. 6. The power system of claim 5, the motor is one; a power system including a power transmission mechanism that transmits the rotational driving force of the motor to the supply pump and the recovery pump;

7. 6. The power system of claim 5, a motor control unit for controlling the motor; When the on-off valve is in an open state, the motor control unit controls the motor to make the torque of the motor a predetermined target torque.

8. 8. The power system of claim 7, When the on-off valve is in a closed state, the motor control unit controls the motor to set the rotation speed of the supply pump to a target rotation speed.

9. 10. The power system of claim 1, The power unit is a bearing portion that rotatably supports the rotor; a lubrication flow path that circulates the oil to the bearing portion; A power system having:

10. A method for controlling a power system, comprising: The power system includes: A power unit; a supply pump for delivering liquid oil for lubricating the power plant; a supply flow path that guides the oil sent from the supply pump to the power unit; a recovery pump for recovering the oil that has circulated through the power unit; a recovery flow path that guides the oil that has circulated in the power unit to the recovery pump; a circulation flow path for guiding the oil recovered by the recovery pump to the supply pump; a bypass flow path connecting the supply flow path and the circulation flow path; an on-off valve that opens and closes the bypass flow path; a motor for driving the supply pump and the recovery pump; a motor control unit that controls the motor; Equipped with A control method for a power system, wherein, when the on-off valve is in an open state, the motor control unit controls the motor to set the torque of the motor to a predetermined target torque.

11. 11. A method for controlling a power system according to claim 10, comprising: The method for controlling a power system, wherein, when the on-off valve is in a closed state, the motor control unit controls the motor to set the rotation speed of the supply pump to a target rotation speed.

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