Lubrication system

Abstract

To provide a lubrication system for smoothly supplying oil to a lubrication object by using oil, such as electrical machinery.SOLUTION: A lubrication system 30 includes: a first pump 38 capable of supplying oil sucked from a tank 36 to a lubrication object 24; a second pump 46 capable of discharging oil sucked from the lubrication object 24 to the tank; a relief valve 54 capable of releasing oil in a first flow passage 42 to the tank 36; a third pump 62 capable of discharging oil sucked via a suction port 62i to the tank 36; a selector valve 60 capable of selectively switching a communication destination of the suction port 62i to either one of the lubrication object 24 or the tank 36; and a valve control section 82 that switches the communication destination of the suction port 62i by controlling the selector valve 60.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

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

[0003] Meanwhile, Patent Document 1 discloses a lubrication device for a vehicle internal combustion engine. The lubrication device uses a pump to suck up lubricating oil from an oil pan and supplies it to parts that require lubrication (such as bearings of the crankshaft of the internal combustion engine). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-153013 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable to smoothly supply oil to objects to be lubricated by oil, such as electrical machinery.

[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 first pump capable of supplying oil sucked from a tank to an object lubricated by oil; a second pump capable of discharging the oil sucked from the object to the tank; a relief valve capable of releasing the oil in the first flow path to the tank via a second flow path separate from the first flow path when the pressure value of the oil in the first flow path between the first pump and the object to be lubricated reaches or exceeds a predetermined value; a third pump capable of discharging the oil sucked through an intake port to the tank; a switching valve capable of selectively switching the connection of the intake port to either the object to be lubricated or the tank; and a valve control unit that switches the connection of the intake port of the third pump by controlling the switching valve. [Effects of the Invention]

[0008] According to the present invention, oil can be smoothly supplied to an object to be lubricated with oil. [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 flowchart of the circuit determination process. [Figure 4] FIG. 4 is a diagram showing the upper limit temperature of oil that can be collected by the second pump. [Figure 5] FIG. 5A is a diagram showing the rotation speed of each pump (the rotation speed of the gas turbine engine) over time. FIG. 5B is a diagram showing the oil temperature detected by a temperature sensor over time. FIG. 5C is a diagram showing the oil pressure value detected by a pressure sensor over time. FIG. 5D is a diagram showing the flow rate of oil supplied to the generator and the flow rate of oil flowing through the relief valve over time. FIG. 5E is a diagram showing the opening degree of the relief valve over time. FIG. 5F is a diagram showing whether the lubrication circuit functions as a temperature increase circuit or a normal circuit over time. DETAILED DESCRIPTION OF THE INVENTION

[0010] The lubrication system lubricates an object by supplying oil to the object. The lubrication system may be provided in various devices. In this specification, a lubrication system installed in an aircraft will be described.

[0011] Generally, when a lubrication system first starts operating, the oil is cold and viscous, making it difficult for the oil to flow. However, the lubrication system described in this specification can quickly heat the oil after starting operation, allowing the oil to flow easily.

[0012] [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.

[0013] The aircraft 10 is equipped with a gas turbine engine (internal combustion 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 in the aircraft 10. The gas turbine engine 22 and the generator 24 are included in a lubrication system 30 shown in FIG. 2.

[0014] [2. Configuration of Lubrication System 30] 2 is a schematic diagram of the lubrication system 30. In the lubrication system 30 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 30 includes a lubrication circuit 32 and a control device 34.

[0015] The lubrication circuit 32 includes the 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.

[0016] The lubrication circuit 32 includes a first pump 38, a flow path 40, and a flow path (first 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 44.

[0017] The lubrication circuit 32 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 52.

[0018] The lubrication circuit 32 includes a relief valve 54, a flow path 56, and a flow path (second flow path) 58. 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 tank 36 via the flow path 58. Note that the outlet 54o may be connected to the flow path 40 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) reaches or exceeds a predetermined valve opening pressure value (predetermined value). This allows the relief valve 54 to communicate between the flow path 56 and the flow path 58 (tank 36). The relief valve 54 can release oil in the flow path 42 to the tank 36 via the flow path 58.

[0019] The lubrication circuit 32 includes a switching valve 60, one or more third pumps 62, a flow path 64, a flow path 66, a flow path 68, and a flow path 70. The switching valve 60 includes a first port 60a, a second port 60b, and a third port 60c. The switching valve 60 is a solenoid valve and a two-position directional control valve. When the switching valve 60 is in a non-energized (de-energized) state, the first port 60a and the second port 60b communicate with each other. When the switching valve 60 is in a powered (energized) state, the third port 60c and the second port 60b communicate with each other. The first port 60a is connected to the flow path 48 via the flow path 64. The second port 60b is connected to the suction port 62i of the third pump 62 via the flow path 66. The third port 60c is connected to the tank 36 via the flow path 70. The switching valve 60 can selectively switch the communication destination of the suction port 62i of the third pump 62 to either the generator 24 or the tank .

[0020] When the switching valve 60 is in a non-energized (de-energized) state, the third port 60c and the second port 60b may be communicated with each other, and when the switching valve 60 is in a powered (energized) state, the first port 60a and the second port 60b may be communicated with each other. Also, instead of a two-position directional control valve, another valve (for example, a three-way valve) may be used as the switching valve 60.

[0021] The third pump 62 has an intake port 62i and an exhaust port 62d. The intake port 62i is connected to the second port 60b of the switching valve 60 via a flow path 66. The exhaust port 62d is connected to the tank 36 via a flow path 68. The third pump 62 can discharge oil drawn in via the intake port 62i into the tank 36 via the flow path 68 and the flow path 50. The third pump 62 is a scavenge pump 52, similar to the second pump 46.

[0022] As shown in FIG. 2, the lubrication circuit 32 of this embodiment is provided with two third pumps 62, but it may also be provided with one third pump 62, or three or more third pumps 62.

[0023] The oil flowing out from the generator 24 contains gas. For this reason, it is preferable that the capacity of the scavenge pump 52 that recovers oil from the generator 24 be larger than the capacity of the feed pump 44 that supplies oil to the generator 24. The lubrication circuit 32 of this embodiment includes multiple scavenge pumps 52 (the second pump 46 and one or more third pumps 62). For this reason, the capacity of each scavenge pump 52 does not need to be larger than the capacity of the feed pump 44 (the first pump 38). For example, by configuring the first pump 38, the second pump 46, and the third pump 62 as pumps of the same type, the manufacturing costs and maintenance costs of the lubrication system 30 can be reduced.

[0024] The rotating shafts of the first pump 38, the second pump 46, and the one or more third pumps 62 are connected to the rotating shaft of the gas turbine engine 22 via the gearbox 26. By driving the first pump 38, the second pump 46, and the third pump 62 on the same shaft as in this embodiment, the lubrication circuit 32 can be made compact.

[0025] The lubrication circuit 32 includes a pressure sensor (pressure detection unit) 72 and a temperature sensor (temperature detection unit) 74. The pressure sensor 72 detects the pressure value of the oil in the flow path . The temperature sensor 74 detects the temperature of the oil in the flow path .

[0026] The control device 34 includes a calculation unit 76 and a storage unit 78. The control device 34 may be configured by, for example, an ECU (Electronic Control Unit).

[0027] The arithmetic unit 76 may be configured by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the arithmetic unit 76 may be configured by processing circuitry. At least a part of the arithmetic unit 76 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 arithmetic unit 76 may be realized by an electronic circuit including discrete devices.

[0028] The calculation unit 76 includes a pump control unit 80 and a valve control unit 82. The pump control unit 80 and the valve control unit 82 can be realized by the calculation unit 76 executing a program stored in the storage unit 78. The pump control unit 80 controls the rotation speed of each pump. For example, the pump control unit 80 may change the gear ratio of the gearbox 26 or control the gas turbine engine 22. The valve control unit 82 controls the switching valve 60 based on the pressure detected by the pressure sensor 72 and the temperature detected by the temperature sensor 74. For example, the valve control unit 82 switches between energizing and de-energizing the switching valve 60 to switch the communication destination of the suction port 62i of the third pump 62.

[0029] The storage unit 78 is a computer-readable storage medium. The storage unit 78 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 78 may be provided in the above-mentioned processor, integrated circuit, etc.

[0030] [3 Operation of Lubrication System 30] The lubrication circuit 32 lubricates the generator 24 by supplying oil to and recovering oil from the generator 24. In this specification, the operation of the lubrication circuit 32 to lubricate the generator 24 is referred to as lubrication operation. The lubrication operation is performed while the generator 24 is rotating (while the gas turbine engine 22 is rotating).

[0031] At the start of lubrication operation, the oil is cold and highly viscous. High oil viscosity increases the oil pressure loss in the generator 24, resulting in a high pressure value in the flow path 42. Increasing the rotation speed of each pump in this state prevents the oil from flowing smoothly through the lubrication circuit 32. Therefore, the lubrication system 30 operates to heat the oil by driving each pump at a speed lower than the normal rotation speed until the oil temperature exceeds a predetermined threshold temperature. This operation is referred to herein as the temperature-raising operation. After the oil temperature exceeds the predetermined threshold temperature, the lubrication system 30 operates to supply sufficient oil to the generator 24 by rotating each pump at the normal rotation speed. This operation is referred to herein as the normal operation. The predetermined threshold temperature at which the temperature is switched from the temperature-raising operation to the normal operation is referred to herein as the normal operation lower-limit temperature.

[0032] When the pressure value in the flow path 42 reaches or exceeds the opening pressure value of the relief valve 54, the relief valve 54 opens. As a result, at the beginning of lubrication operation, some of the oil discharged from the first pump 38 to the flow path 42 flows through the flow path 56, the relief valve 54, and the flow path 58 and returns to the tank 36. As a result, only a small amount of oil is supplied to the generator 24, and only a small amount of oil flows out of the generator 24.

[0033] In this state, the flow rate of oil flowing out of the generator 24 is lower than the flow rate of oil that can be recovered by the second pump 46. In this state, the second pump 46 can recover the oil flowing out of the generator 24. On the other hand, while the second pump 46 is operating, the third pump 62 does not need to recover the oil flowing out of the generator 24.

[0034] Incidentally, a portion of the energy given to the pump to operate it is converted into heat. Therefore, the oil drawn into the pump is heated by the pump. The oil temperature rises as the pump continues to draw and discharge oil. In the lubrication circuit 32, the pump is a heat source. By supplying a large amount of oil to the pump, the oil temperature can be raised quickly. However, if only a small amount of oil flows out of the generator 24, only a small amount of oil is supplied to the scavenge pump 52 (the second pump 46 and the third pump 62).

[0035] Therefore, in this embodiment, when the amount of oil flowing out of the generator 24 is small, the third pump 62 is not used as a pump for recovering oil from the generator 24, but is used as a pump dedicated to raising the temperature of the oil in the tank 36. In this case, the valve control unit 82 controls the switching valve 60 to connect the third port 60c and the second port 60b. Then, the suction port 62i of the third pump 62 is connected to the tank 36 via the flow path 66, the switching valve 60, and the flow path 70. As a result, the third pump 62 draws oil from the tank 36 via the flow path 66, the switching valve 60, and the flow path 70. The oil drawn into the third pump 62 is heated by the third pump 62, and its temperature is raised.

[0036] As the temperature of the oil rises, the flow rate of oil flowing through the generator 24 increases. When the temperature of the oil rises to a certain level, the flow rate of oil flowing out of the generator 24 exceeds the flow rate of oil that the second pump 46 can recover. At this point, the valve control unit 82 controls the switching valve 60 to connect the first port 60a and the second port 60b. Then, the suction port 62i of the third pump 62 communicates with the oil outlet 24o of the generator 24 via the flow path 66, the switching valve 60, the flow path 64, and the flow path 48. As a result, the third pump 62 recovers (sucks) oil from the generator 24 via the flow path 66, the switching valve 60, the flow path 64, and the flow path 48. The oil recovered by the third pump 62 is heated by the third pump 62 and its temperature increases.

[0037] As described above, the valve control unit 82 controls the switching position of the switching valve 60 according to the state of the lubrication circuit 32 so as to effectively utilize the scavenge pump 52 (the second pump 46 and the third pump 62). The valve control unit 82 controls the switching valve 60 so that the third port 60c and the second port 60b communicate with each other during a predetermined period at the beginning of the lubrication operation. This allows the flow path 70 to communicate with the flow path 66. In this specification, the lubrication circuit 32 in which the flow path 70 of the switching valve 60 communicates with the flow path 66 is referred to as a temperature rise circuit. Furthermore, after the above-mentioned predetermined period has ended, the valve control unit 82 controls the switching valve 60 so that the first port 60a and the second port 60b communicate with each other. This allows the flow path 64 to communicate with the flow path 66. In this specification, the lubrication circuit 32 in which the flow path 64 and the flow path 66 communicate with each other is referred to as a normal circuit.

[0038] [4 Circuit Determination Processing] 3 is a flowchart of the circuit determination process. The circuit determination process is a process in which the valve control unit 82 selects either the heating circuit or the normal circuit. When the gas turbine engine 22 starts, the first pump 38, the second pump 46, and one or more third pumps 62 start. This starts the lubrication operation. During the lubrication operation, the valve control unit 82 performs the circuit determination process described below at predetermined time intervals.

[0039] In step S1, the valve control unit 82 determines whether the relief valve 54 is open. The valve control unit 82 determines that the relief valve 54 is open when the pressure value detected by the pressure sensor 72 is equal to or greater than the opening pressure value of the relief valve 54. On the other hand, the valve control unit 82 determines that the relief valve 54 is not open when the pressure value detected by the pressure sensor 72 is less than the opening pressure value of the relief valve 54. The opening pressure value of the relief valve 54 is pre-stored in the memory unit 78. If the relief valve 54 is open (step S1: YES), the process proceeds to step S2. On the other hand, if the relief valve 54 is not open (step S1: NO), the process proceeds to step S4.

[0040] When the process proceeds from step S1 to step S2, the valve control unit 82 determines whether or not the oil flowing out of the generator 24 can be recovered by only the second pump 46. Specifically, if the flow rate of the oil flowing out of the generator 24 is equal to or less than the flow rate of oil that the second pump 46 can recover, the valve control unit 82 determines that the oil flowing out of the generator 24 can be recovered by only the second pump 46. On the other hand, if the flow rate of the oil flowing out of the generator 24 is greater than the flow rate of oil that the second pump 46 can recover, the valve control unit 82 determines that the oil flowing out of the generator 24 cannot be recovered by only the second pump 46. The determination made in step S2 will be described below.

[0041] When the relief valve 54 is open, the pressure value of the oil flowing through the lubrication circuit 32 is a constant value (the opening pressure value of the relief valve 54). In this state, the flow rate of oil flowing out of the generator 24 depends on the oil temperature. Meanwhile, the flow rate of oil that can be recovered by the second pump 46 depends on the rotation speed of the second pump 46. Here, if the flow rate of oil flowing out of the generator 24 is replaced with the oil temperature, and the flow rate of oil that can be recovered by the second pump 46 is replaced with the rotation speed of the second pump 46, the characteristics shown in FIG. 4 are established.

[0042] The characteristic shown in FIG. 4 indicates the upper limit temperature of oil that can be recovered by the second pump 46. This upper limit temperature correlates with the upper limit flow rate of oil that can be recovered by the second pump 46. As shown in FIG. 4, the upper limit temperature increases as the rotation speed increases. The characteristic shown in FIG. 4 can be obtained by actually performing lubrication operation. For example, the characteristic shown in FIG. 4 can be obtained by actually measuring the flow rate of oil that can be recovered by the second pump 46 and the oil temperature for each rotation speed of the second pump 46. The characteristic shown in FIG. 4 is stored in advance in the memory unit 78. Based on this characteristic and the temperature detected by the temperature sensor 74, the valve control unit 82 determines whether the oil flowing out of the generator 24 can be recovered by the second pump 46 alone.

[0043] When the temperature detected by the temperature sensor 74 is equal to or lower than the upper limit temperature determined in accordance with the rotation speed of the second pump 46, the valve control unit 82 determines that the oil flowing out of the generator 24 can be recovered by the second pump 46 alone. On the other hand, when the temperature detected by the temperature sensor 74 is higher than the upper limit temperature determined in accordance with the rotation speed of the second pump 46, the valve control unit 82 determines that the oil flowing out of the generator 24 cannot be recovered by the second pump 46 alone.

[0044] If the oil flowing out from the generator 24 can be collected by only the second pump 46 (step S2: YES), the process proceeds to step S3. On the other hand, if the oil flowing out from the generator 24 cannot be collected by only the second pump 46 (step S2: NO), the process proceeds to step S4.

[0045] When the process proceeds from step S2 to step S3, the valve control unit 82 selects the temperature increase circuit. The valve control unit 82 controls a valve drive circuit (not shown) so that the switching valve 60 is energized (excited). As a result, the switching valve 60 is energized (excited), and the third port 60c and the second port 60b are connected to each other. The suction port 62i of the third pump 62 is connected to the tank 36. As a result, the lubrication circuit 32 functions as a temperature increase circuit.

[0046] In the temperature raising circuit, the second pump 46 collects (sucks) oil flowing out from the generator 24 via the flow path 48 and discharges the collected oil into the tank 36 via the flow path 50. Meanwhile, the third pump 62 sucks oil from the tank 36 via the flow path 70, the switching valve 60, and the flow path 66 and discharges the sucked oil into the tank 36 via the flow path 68 and the flow path 50.

[0047] When the process proceeds from step S1 or step S2 to step S4, the valve control unit 82 selects the normal circuit. The valve control unit 82 controls a valve drive circuit (not shown) so that the switching valve 60 is de-energized (de-magnetized). As a result, the switching valve 60 is de-energized (de-magnetized), and the first port 60a and the second port 60b are connected to each other. The suction port 62i of the third pump 62 is connected to the oil outlet 24o of the generator 24. As a result, the lubrication circuit 32 functions as a normal circuit.

[0048] In the normal circuit, the second pump 46 collects (sucks) oil flowing out from the generator 24 via the flow path 48 and discharges the collected oil into the tank 36 via the flow path 50. On the other hand, the third pump 62 collects (sucks) oil flowing out from the generator 24 via the flow path 48, the flow path 64, the switching valve 60, and the flow path 66 and discharges the collected oil into the tank 36 via the flow path 68 and the flow path 50.

[0049] [5 Lubrication operation time chart] FIG. 5A is a diagram showing the rotation speed of each pump (the rotation speed of the gas turbine engine 22) over time. FIG. 5B is a diagram showing the oil temperature detected by the temperature sensor 74 over time. FIG. 5C is a diagram showing the oil pressure value detected by the pressure sensor 72 over time. FIG. 5D is a diagram showing the flow rate of oil supplied to the generator 24 and the flow rate of oil flowing through the relief valve 54 over time. FIG. 5E is a diagram showing the opening degree of the relief valve 54 over time. FIG. 5F is a diagram showing whether the lubrication circuit 32 functions as a temperature increase circuit or a normal circuit over time.

[0050] At time T1, the gas turbine engine 22 starts. As shown in FIG. 5A, the pump control unit 80 starts the first pump 38, the second pump 46, and the third pump 62 at low speeds. This initiates a temperature-raising operation. Then, as shown in FIG. 5C, the pressure in the flow path 42 rises sharply. This causes the relief valve 54 to open as shown in FIG. 5E, and oil begins to flow through the relief valve 54 as shown in FIG. 5D. As shown in FIG. 5F, the valve control unit 82 causes the lubrication circuit 32 to function as a temperature-raising circuit. That is, the valve control unit 82 connects the third port 60c and the second port 60b of the switching valve 60.

[0051] As the oil circulates through the temperature raising circuit, the temperature of the oil gradually rises, as shown in Fig. 5B. As the oil temperature rises, the viscosity of the oil gradually decreases, and the pressure loss in the generator 24 gradually decreases. Then, as shown in Fig. 5E, the opening of the relief valve 54 gradually decreases. As a result, as shown in Fig. 5D, the flow rate of oil supplied to the generator 24 gradually increases, and the flow rate of oil flowing through the relief valve 54 gradually decreases.

[0052] As shown in Fig. 5D, at time T2, the flow rate of oil supplied to the generator 24 exceeds the upper limit of the flow rate of oil that can be recovered by only the second pump 46. As shown in Fig. 5B, the temperature of the oil exceeds the upper limit of the temperature of oil that can be recovered by the second pump 46. As shown in Fig. 5F, at this timing, the valve control unit 82 causes the lubrication circuit 32 to function as a normal circuit. That is, the valve control unit 82 causes the first port 60a and the second port 60b of the switching valve 60 to communicate with each other.

[0053] As shown in FIG. 5E, at time T3, the relief valve 54 closes. In this state, the oil circulates through the normal circuit. As a result, as shown in FIG. 5B, the oil temperature continues to rise. At time T4, the oil temperature reaches the normal operation lower limit temperature. As shown in FIG. 5A, at this timing, the pump control unit 80 operates the first pump 38, the second pump 46, and the third pump 62 in the normal rotation range, which is higher than the low rotation range. This starts normal operation.

[0054] [6 Other] It should be noted that the lubrication system 30 may include an electric motor instead of the gas turbine engine 22 .

[0055] [7 Effects of this embodiment] In this embodiment, the communication destination of the suction port 62i of the third pump 62 can be selectively switched between the generator 24 and the tank 36. According to this embodiment, the third pump 62 can be used not only as a pump that collects oil from the generator 24, but also as a pump dedicated to heating the oil. According to this embodiment, the oil can be quickly heated by switching the switching valve 60 depending on the oil flow status. This allows the oil to flow easily early, allowing the oil to be smoothly supplied to objects to be lubricated by the oil.

[0056] [8 Notes] The following additional notes are further disclosed regarding the above embodiment.

[0057] (Appendix 1) The lubrication system (30) of the present disclosure includes a first pump (38) capable of supplying oil sucked from a tank (36) to a lubrication object (24) lubricated by oil, a second pump (46) capable of discharging the oil sucked from the lubrication object to the tank, a relief valve (54) capable of releasing the oil in a first flow path (42) between the first pump and the lubrication object to the tank via a second flow path (58) separate from the first flow path when the pressure value of the oil in the first flow path is equal to or higher than a predetermined value, a third pump (62) capable of discharging the oil sucked through an intake port (62i) to the tank, a switching valve (60) capable of selectively switching the communication destination of the intake port to either the lubrication object or the tank, and a valve control unit (82) that switches the communication destination of the intake port of the third pump by controlling the switching valve.

[0058] In the above configuration, the communication destination of the suction port of the third pump can be selectively switched between the lubrication target and the tank. According to the above configuration, the third pump can be used not only as a pump for recovering oil from the lubrication target, but also as a pump dedicated to heating the oil. According to the above configuration, the oil temperature can be quickly raised by switching the switching valve depending on the oil flow conditions. This allows the oil to flow more easily early, allowing the oil to be smoothly supplied to the lubrication target.

[0059] (Appendix 2) In the lubrication system described in Appendix 1, when the oil in the first flow path is released into the tank via the relief valve and the second flow path, the valve control unit may perform a first control to control the switching valve so that the destination of the suction port of the third pump is the tank.

[0060] (Appendix 3) In the lubrication system described in Appendix 2, when the flow rate of the oil discharged from the lubrication target exceeds the flow rate of the oil that can be sucked into the second pump, the valve control unit may switch from the first control to a second control that controls the switching valve so that the destination of the suction port of the third pump becomes the lubrication target.

[0061] (Appendix 4) The lubrication system described in any one of Appendices 1 to 3 may further include a pressure detection unit (72) that detects the pressure value of the oil in the first flow path, and a temperature detection unit (74) that detects the temperature of the oil in the first flow path, and the valve control unit may control the switching valve based on the pressure value detected by the pressure detection unit and the temperature detected by the temperature detection unit.

[0062] The oil flow rate depends on the oil temperature. Therefore, it is possible to control the oil flow rate by detecting the oil temperature instead of detecting the oil flow rate. By using a temperature detection device instead of a flow rate detection device, costs can be reduced.

[0063] (Appendix 5) In the lubrication system described in Appendix 4, the valve control unit may control the switching valve so that the destination of the suction port of the third pump is the tank when the pressure value detected by the pressure detection unit is less than the predetermined value and the temperature detected by the temperature detection unit is less than or equal to an upper limit temperature determined according to the rotation speed of the second pump.

[0064] (Appendix 6) In the lubrication system according to any one of Supplementary Notes 1 to 5, the first pump may be a feed pump (44), and the second pump and the third pump may be scavenge pumps (52).

[0065] According to the above configuration, since multiple pumps, i.e., the second pump and the third pump, function as scavenge pumps, the capacities of the second pump and the third pump do not need to be larger than the capacity of the first pump. Therefore, the first pump, the second pump, and the third pump can be configured as pumps of the same type. This reduces the manufacturing and maintenance costs of the lubrication system.

[0066] (Appendix 7) In the lubrication system according to any one of Supplementary Notes 1 to 6, the first pump, the second pump, and the third pump may be driven by a common actuator.

[0067] According to the above configuration, the first pump, the second pump, and the third pump are driven by a common actuator, so that the circuit can be made compact.

[0068] (Appendix 8) In the lubrication system described in Supplementary Note 7, the actuator may be an internal combustion engine (22).

[0069] (Appendix 9) In the lubrication system described in Supplementary Note 7, the actuator may be an electric motor.

[0070] 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]

[0071] 22...Gas turbine engine (internal combustion engine) 24...Generator (lubrication target) 30...Lubrication system 36...Tank 38...First pump 42...Flow path (first flow path) 44...Feed pump 46...Second pump 52...Scavenge pump 54...Relief valve 58... Flow path (second flow path) 60... Switching valve 62...Third pump 62i...Suction port 72... Pressure sensor (pressure detection unit) 74... Temperature sensor (temperature detection unit) 82...Valve control section

Claims

1. a first pump capable of supplying oil drawn from a tank to an object to be lubricated by the oil; a second pump capable of discharging the oil drawn from the object to be lubricated into the tank; a relief valve that can release the oil in the first flow path to the tank via a second flow path separate from the first flow path when a pressure value of the oil in the first flow path between the first pump and the object to be lubricated becomes equal to or greater than a predetermined value; a third pump that can discharge the oil drawn in through a suction port into the tank; a switching valve that selectively switches the communication destination of the suction port to either the lubrication target or the tank; a valve control unit that controls the switching valve to switch the communication destination of the suction port of the third pump; A lubrication system comprising:

2. 10. The lubrication system of claim 1, A lubrication system in which, when the oil in the first flow path is released into the tank through the relief valve and the second flow path, the valve control unit performs first control to control the switching valve so that the connection destination of the suction port of the third pump is the tank.

3. 3. The lubrication system of claim 2, A lubrication system in which, when the flow rate of the oil discharged from the lubrication target exceeds the flow rate of the oil that can be sucked into the second pump, the valve control unit switches from the first control to the second control, which controls the switching valve so that the destination of the suction port of the third pump becomes the lubrication target.

4. 10. The lubrication system of claim 1, a pressure detection unit that detects the pressure value of the oil in the first flow path; a temperature detection unit that detects the temperature of the oil in the first flow path; Further provided with The valve control unit controls the switching valve based on the pressure value detected by the pressure detection unit and the temperature detected by the temperature detection unit.

5. 5. The lubrication system of claim 4, The valve control unit controls the switching valve so that the suction port of the third pump is connected to the tank when the pressure value detected by the pressure detection unit is less than the predetermined value and the temperature detected by the temperature detection unit is equal to or lower than an upper limit temperature determined according to the rotation speed of the second pump.

6. 10. The lubrication system of claim 1, the first pump is a feed pump; The lubrication system, wherein the second pump and the third pump are scavenge pumps.

7. 10. The lubrication system of claim 1, The lubrication system, wherein the first pump, the second pump, and the third pump are driven by a common actuator.

8. 8. The lubrication system of claim 7, The actuator is an internal combustion engine.

9. 8. The lubrication system of claim 7, The lubrication system wherein the actuator is an electric motor.

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