Propulsion devices and fluid machinery

Abstract

To provide a propulsion device and a fluid machine with further improved efficiency.SOLUTION: A propulsion device includes: an airframe extending in the axial direction; a first propeller capable of rotating around an axis; a second propeller provided on downstream side of the first propeller capable of rotating around an axis; an electric motor for rotating and driving one of the first propeller and the second propeller; and a heat engine for rotating and driving the other one of the first propeller and the second propeller.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a propulsion device and a fluid machine. [Background technology]

[0002] A known propulsion device mounted on a machine that navigates underwater is, for example, that described in Patent Document 1. The device described in Patent Document 1 includes a generator driven by a gas turbine, an electric motor driven by the electricity generated by the generator, and an electricity storage device that stores the generated electricity.

[0003] The gas turbine is always operated in a high-output range to drive the generator. The generated electricity is supplied to the electric motor and the energy storage device. When the energy storage device reaches the required maximum charge, the gas turbine is shut down. In addition, only one propeller is rotated by the electric motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-35297 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the configuration disclosed in Patent Document 1, energy loss occurs when the power of the gas turbine is converted into electricity by the generator. Also, since the driving force of the propeller needs to be provided solely by the electric motor, the electric motor becomes large. As a result, there is a risk that the efficiency of the propulsion device will be reduced.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a propulsion device and a fluid machine with further improved efficiency. [Means for solving the problem]

[0007] Book The disclosed propulsion device comprises an airframe extending in an axial direction, a first propeller rotatable about the axis, a second propeller provided downstream of the first propeller and rotatable about the axis, an electric motor that rotationally drives one of the first propeller and the second propeller, and a heat engine that rotationally drives the other of the first propeller and the second propeller, a shroud that surrounds the airframe from the outer periphery and forms a flow path between the airframe and the shroud, the first propeller provided in the flow path, the second propeller provided in the flow path downstream of the first propeller, the electric motor provided within the shroud, and the heat engine provided on the airframe. The propulsion device of the present disclosure comprises an airframe extending in an axial direction, a first propeller rotatable around the axis, a second propeller located downstream of the first propeller and rotatable around the axis, an electric motor that rotationally drives one of the first propeller and the second propeller, a heat engine that rotationally drives the other of the first propeller and the second propeller, and a control unit that controls the operation of the electric motor and the heat engine, and the control unit operates only the electric motor when the speed generated by the propulsion device is below a predetermined threshold, and operates the heat engine when the speed is equal to or greater than the threshold. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a propulsion device and a fluid machine with further improved efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing the configuration of a propulsion device and an underwater vehicle (fluid machine) according to an embodiment of the present disclosure. [Figure 2] 3 is a graph showing an example of efficiency characteristics of a fuel cell system and a combustion engine. [Figure 3] 1 is a graph showing efficiency characteristics of an electric motor and a heat engine. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Configuration of underwater vehicle) An underwater vehicle 100 (fluid machine) according to an embodiment of the present disclosure will now be described with reference to Fig. 1. As shown in Fig. 1, the underwater vehicle 100 comprises a vehicle main body 80 (fluid machine main body) and a propulsion device 90. The vehicle main body 80 is configured by a pressure-resistant container extending along an axis O. The vehicle main body 80 accommodates various devices, power sources, communication equipment, sensors, etc. required for underwater navigation.

[0011] (Propulsion device configuration) The propulsion device 90 is integrally attached to the rear of the underwater vehicle main body 80. The propulsion device 90 is a device for propelling the underwater vehicle 100 underwater. The propulsion device 90 has a body 1, a shroud 2, a first propeller 3, a second propeller 4, an electric motor 5, a heat engine 6, a transmission 7, an inverter 8, a battery 9, a first bearing 10, a second bearing 11, a rotating shaft 71, and a control unit 200.

[0012] (Aircraft configuration) The body 1 is integral with the naval vessel main body 80. The body 1 may be part of the naval vessel main body 80. The body 1 extends along the axis O. The body 1 of this embodiment has a truncated cone shape whose diameter decreases from one side in the direction of the axis O (hereinafter referred to as the "upstream side") to the other side in the direction of the axis O (hereinafter referred to as the "downstream side").

[0013] (Shroud configuration) The shroud 2 has a cylindrical shape that covers the airframe 1 from the outside. The shroud 2 has an airfoil-like cross-sectional shape in a cross section including the axis O. In this embodiment, the shroud 2 gradually reduces in diameter from the upstream side to the downstream side. The shape of the shroud 2 can be changed in various ways to correspond to the shape of the naval vessel main body 80.

[0014] The shroud 2 is fixed to the airframe 1 by a plurality of struts 2a. The struts 2a extend radially outward from the airframe 1. The struts 2a are arranged at intervals in the circumferential direction. The struts 2a extend obliquely downstream as they extend radially outward. The radially outer ends of the struts 2a are fixed near the upstream end of the shroud 2. The space between the shroud 2 and the airframe 1 forms a flow path F through which water flows.

[0015] (First propeller configuration) The first propeller 3 has an inner ring 31 and first blades 32. The inner ring 31 has an annular shape centered on the axis O. The inner ring 31 is supported rotatably about the axis O by a first bearing unit 10 provided on the outer peripheral surface of the aircraft body 1. The first bearing unit 10 has an upstream thrust bearing 10a, a downstream thrust bearing 10b, and a journal bearing 10c. The upstream thrust bearing 10a faces the inner ring 31 from the upstream side and thus bears a thrust load (load in the direction of the axis O) toward the upstream side. The downstream thrust bearing 10b faces the inner ring 31 from the downstream side and thus bears a thrust load toward the downstream side. The journal bearing 10c faces the inner ring 31 from the radially inner side and therefore bears a radial load.

[0016] The outer peripheral surface of the inner ring 31 is tapered by gradually reducing its diameter toward the downstream side. Therefore, the outer peripheral surface of the airframe 1 and the outer peripheral surface of the inner ring 31 are substantially flush with each other. First blades 32 are provided on the outer peripheral surface of the inner ring 31. The first blades 32 extend radially outward from the inner ring 31 and are arranged at intervals in the circumferential direction. These first blades 32 are driven to rotate around the axis O together with the inner ring 31, thereby generating a propulsive force toward the downstream side.

[0017] (Electric motor configuration) The electric motor 5 is a device for driving the first propeller 3 to rotate. The electric motor 5 is provided inside the shroud 2. In other words, this electric motor 5 is an outer circumferential drive motor. The electric motor 5 is housed in a recess formed in the inner circumferential surface of the shroud 2. The electric motor 5 has a stator 51 fixed to the shroud 2 side and a rotor 52 fixed to the radially outer end of the first blade 32. The stator 51 has a plurality of coils, and the rotor 52 has a permanent magnet. Of these, power from a battery 9 is supplied to the stator 51 via an inverter 8. The battery 9 and inverter 8 are housed inside the airframe 1.

[0018] (Configuration of the second propeller) The second propeller 4 is provided at the downstream end of the airframe 1 with its rotation axis on axis O. In other words, the second propeller 4 is located downstream of the first propeller 3. The rotation direction of the second propeller 4 is opposite to the rotation direction of the first propeller 3. In other words, the first propeller 3 and the second propeller 4 form contra-rotating propellers.

[0019] The second propeller 4 has a boss portion 41 and second blades 42. The boss portion 41 has a disk shape centered on the axis O. The second blades 42 extend radially outward from the outer circumferential surface of the boss portion 41 and are arranged at intervals in the circumferential direction. As described above, since the diameter of the shroud 2 decreases toward the downstream side, the radial dimension of the second blades 42 is set smaller than the radial dimension of the first blades 32.

[0020] A rotating shaft 71 is attached to the center of the boss portion 41 (i.e., at the position of the axis O). The rotating shaft 71 is rod-shaped and extends along the axis O. The rotating shaft 71 is supported rotatably around the axis O by a second bearing portion 11 provided at the downstream end of the machine body 1. The second bearing portion 11 is a journal bearing.

[0021] (Configuration of heat engine and transmission) The heat engine 6 is a device for driving the second propeller 4 to rotate. Specifically, a gas turbine is preferably used as the heat engine 6. The heat engine 6 is driven by fuel supplied from a tank 61. The rotational driving force of the heat engine 6 is first transmitted to a transmission 7. The upstream end of the rotating shaft 71 is connected to the transmission 7. The transmission 7 is a device for adjusting the rotation speed of the rotating shaft 71. It is also possible to adopt a configuration in which the rotating shaft 71 is directly rotated only by the heat engine 6, without providing the transmission 7.

[0022] (Configuration of control unit) The control unit 200 is a device for controlling the operation of the electric motor 5 and the heat engine 6. When the underwater vehicle 100 is in the low speed range, the control unit 200 drives only the electric motor 5. That is, in the low speed range, only the first propeller 3 is rotationally driven. On the other hand, when the underwater vehicle 100 is in the high speed range, the control unit 200 drives the heat engine 6 in addition to the electric motor 5. As a result, the first propeller 3 and the second propeller 4 are rotationally driven.

[0023] (Action and effect) Next, the operation of the underwater vehicle 100 and the propulsion device 90 will be described. To operate the propulsion device 90, the control unit 200 first drives the electric motor 5 using power from the battery 9. Driving the electric motor 5 causes the first propeller 3 to rotate around the axis O. This pushes the water in the flow path F downstream, providing propulsive force to the underwater vehicle 100. When the speed of the underwater vehicle 100 is below a predetermined threshold, propulsive force is obtained in this way only by driving the first propeller 3 with the electric motor 5.

[0024] On the other hand, when the speed of the underwater vehicle 100 exceeds the threshold value, the control unit 200 drives the heat engine 6 in addition to the electric motor 5. This also rotates the second propeller 4, further increasing the speed of the underwater vehicle 100. Each time the speed range changes, the underwater vehicle 100 travels underwater by repeatedly switching and disconnecting the drive source as described above.

[0025] As described above, with the above configuration, the first propeller 3 is rotationally driven by the electric motor 5, and the second propeller 4 is rotationally driven by the heat engine 6. This makes it possible to change the drive source used for each speed range, for example. As a result, the propulsion device 90 can be operated more efficiently.

[0026] Furthermore, according to the above configuration, by using contra-rotating propellers in which the rotation directions of the upstream first propeller 3 and the downstream second propeller 4 are opposite, the swirling flow generated by the first propeller 3 can be recovered by the second propeller 4. This reduces the rotation loss in the wake of the second propeller 4. This further improves the propulsion performance of the propulsion device 90.

[0027] In addition, with the above configuration, the electric motor 5 is a peripheral drive motor provided inside the shroud 2, not inside the airframe 1, and is therefore constantly cooled by the water flowing around the shroud 2. This allows the electric motor 5 to be cooled without providing any other cooling device. As a result, the efficiency of the propulsion unit 90 can be further improved.

[0028] Furthermore, since the two power sources, the electric motor 5 and the heat engine 6, are independent of each other, there is no need to add a generator, reducer, or auxiliary equipment to supply power from the heat engine 6 to the electric motor 5, which avoids complicating the system and increasing the installation space.

[0029] As shown in Figure 2, when a fuel cell system is used as a drive source, it exhibits particularly high efficiency characteristics in the low-speed range where the load is small, and also exhibits a certain degree of high efficiency characteristics in the high-speed range where the load is large. On the other hand, when a heat engine such as a diesel engine or a spark-ignition engine is used as a drive source, the efficiency characteristics tend to decrease in the low-speed range where the load is small. A similar tendency is observed when a gas turbine is used as a heat engine. In contrast, with the above configuration, the first propeller 3 is driven only by the electric motor 5 in the low-speed range where the speed is below the threshold. That is, as shown in the graph in Fig. 3, the electric motor 5 has better efficiency characteristics in the low-output range than the heat engine 6, and therefore the above configuration can improve the efficiency of the propulsion device 90. Furthermore, since the propulsion device 90 is driven only by the electric motor 5, quietness in the low-speed range can also be improved.

[0030] Furthermore, in the high-speed range where the speed is equal to or higher than a threshold, the heat engine 6 is operated in addition to the electric motor 5, thereby further improving the output. As described above, the efficiency characteristics of a gas turbine as the heat engine 6 in the low-speed range are inferior to those of the electric motor 5. Therefore, by driving the electric motor 5 mainly in the low-speed range as described above and then driving the heat engine 6 when the high-speed range is reached, the efficiency characteristics of the electric motor 5 and the heat engine 6 can complement each other.

[0031] Furthermore, with the above configuration, the electric motor 5 is driven using power supplied from the battery 9, which is independent of the heat engine 6. This makes it possible to avoid the decrease in efficiency at low speeds where the load on the heat engine is small, which occurs when, for example, power generated by the heat engine 6 is supplied to the electric motor 5, and also eliminates losses that occur during power conversion. This makes it possible to further improve the efficiency of the propulsion device 90.

[0032] The above describes an embodiment of the present disclosure. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, in the embodiment, the first propeller 3 is driven by the electric motor 5, and the second propeller 4 is driven by the heat engine 6. However, this is not limited to this, and the first propeller 3 may be driven by the heat engine 6, and the second propeller 4 may be driven by the electric motor 5.

[0033] Furthermore, in the above embodiment, an example was described in which the cross-sectional shape of the shroud 2 was an airfoil shape, but it does not necessarily have to be an airfoil shape. The cross-sectional shape of the shroud 2 is preferably a streamlined shape, but may be another shape, for example, a rectangular shape. Even in this case, the shroud 2 reduces in diameter toward the downstream side, thereby defining a flow path whose cross-sectional area decreases toward the downstream side.

[0034] In the above embodiment, an example has been described in which the propulsion device 90 according to the present disclosure is applied to an underwater vehicle 100. However, this is not limiting, and the propulsion device 90 may be applied to, for example, a ship that navigates on the water. The configuration of the propulsion device 90 may also be applied to other fluid machinery used underwater, such as a pump. Furthermore, the present invention may be applied not only to fluid machinery that pumps water, but also to fluid machinery that pumps other liquids, such as oil.

[0035] <Additional Notes> The propulsion device 90 and the underwater vehicle 100 (fluid machinery) described in each embodiment can be understood, for example, as follows.

[0036] (1) The propulsion device 90 according to the first aspect comprises an airframe 1 extending in the direction of an axis O, a first propeller 3 rotatable around the axis O, a second propeller 4 located downstream of the first propeller 3 and rotatable around the axis O, an electric motor 5 that drives and rotates one of the first propeller 3 and the second propeller 4, and a heat engine 6 that drives and rotates the other of the first propeller 3 and the second propeller 4.

[0037] According to the above configuration, one of the first propeller 3 and the second propeller 4 is rotationally driven by the electric motor 5, and the other of the first propeller 3 and the second propeller 4 is rotationally driven by the heat engine 6. This makes it possible to change the drive source used for each speed range, for example. As a result, the propulsion device 90 can be operated more efficiently.

[0038] (2) The propulsion device 90 of the second aspect comprises a shroud 2 that is arranged to surround the fuselage 1 from the outer periphery and forms a flow path F between the shroud 2 and the fuselage 1, the first propeller 3 that is arranged in the flow path F, the second propeller 4 that is arranged downstream of the first propeller 3 in the flow path F, the electric motor 5 that is arranged within the shroud 2, and the heat engine 6 that is arranged on the fuselage 1.

[0039] According to the above configuration, the electric motor 5 is a peripheral drive motor that is provided inside the shroud 2 and not inside the airframe 1, and is therefore constantly cooled by the water that flows around the shroud 2. This allows the electric motor 5 to be cooled without providing any other cooling device. As a result, the efficiency of the propulsion unit 90 can be further improved.

[0040] (3) In the propulsion device 90 according to the third aspect, the first propeller 3 and the second propeller 4 rotate in opposite directions.

[0041] According to the above configuration, by using contra-rotating propellers in which the rotation directions of the upstream first propeller 3 and the downstream second propeller 4 are opposite, the swirling flow generated by the first propeller 3 can be recovered by the second propeller 4. As a result, the rotation loss in the wake of the second propeller 4 can be reduced.

[0042] (4) In the propulsion device 90 according to the fourth aspect, the electric motor 5 is an outer circumferential drive motor having a stator 51 fixed to the shroud 2 and a rotor 52 fixed to the outer periphery of one of the first propeller 3 and the second propeller 4 radially inside the stator 51.

[0043] According to the above configuration, the electric motor 5 is a peripheral drive motor that is provided inside the shroud 2 and not inside the airframe 1, and is therefore constantly cooled by the water that flows around the shroud 2. This allows the electric motor 5 to be cooled without providing any other cooling device. As a result, the efficiency of the propulsion unit 90 can be further improved.

[0044] (5) The propulsion device 90 according to the fifth aspect further includes a control unit 200 that controls the operation of the electric motor 5 and the heat engine 6, and the control unit 200 operates only the electric motor 5 when the speed generated by the propulsion device 90 is below a predetermined threshold, and operates the heat engine 6 when the speed is equal to or greater than the threshold.

[0045] According to the above configuration, in the low-speed range where the speed is below a threshold, one of the first propeller 3 and the second propeller 4 is driven only by the electric motor 5. Since the electric motor 5 has better efficiency characteristics in the low-output range than the heat engine 6, the above configuration can improve the efficiency of the propulsion device 90. Furthermore, since the propulsion device 90 is driven only by the electric motor 5, quietness can also be improved. Furthermore, in the high-speed range where the speed is above a threshold, the heat engine 6 is operated in addition to the electric motor 5, thereby further improving output.

[0046] (6) In the propulsion device 90 according to the sixth aspect, the electric motor 5 drives one of the first propeller 3 and the second propeller 4 to rotate using electric power supplied from the battery 9 .

[0047] According to the above configuration, the electric motor 5 is driven using power supplied from the battery 9 independent of the heat engine 6. This makes it possible to avoid the decrease in efficiency at low speeds where the load on the heat engine is small, which occurs when, for example, power generated by the heat engine 6 is supplied to the electric motor 5, and also eliminates losses that occur during power conversion. This makes it possible to further improve the efficiency of the propulsion device 90.

[0048] (7) A fluid machine (underwater vehicle 100) according to a seventh aspect includes a fluid machine main body (underwater vehicle main body 80) and a propulsion device 90 according to any one of the above aspects provided on the fluid machine main body.

[0049] According to the above configuration, the efficiency of the fluid machine can be improved. [Explanation of symbols]

[0050] 100 Underwater vehicle 90 Propulsion device 1 aircraft 2 Shroud 2a Strut 3 First Propeller 4 Second Propeller 5 Electric motor 6 Heat Engines 7. Transmission 8 inverters 9. Battery 10 First bearing part 10a Upstream thrust bearing 10b Downstream thrust bearing 10c journal bearing 11 Second bearing part 31 Inner ring 32 First Feather 41 Boss section 42 Second Feather 51 Stator 52 rotor 61 Tank 71 Rotation axis 80 Vehicle body 200 control section

Claims

1. an axially extending fuselage; a first propeller rotatable about the axis; a second propeller provided downstream of the first propeller and rotatable about the axis; an electric motor that rotates and drives one of the first propeller and the second propeller; a heat engine that rotationally drives the other of the first propeller and the second propeller; Equipped with a shroud that is provided to surround the airframe from an outer periphery side and forms a flow path between the airframe and the shroud; The first propeller provided in the flow path; the second propeller provided downstream of the first propeller in the flow path; the electric motor provided within the shroud; The heat engine provided on the airframe; A propulsion device comprising:

2. The electric motor is 2. The propulsion device according to claim 1, wherein the propulsion device is a peripheral drive motor including a stator fixed to the shroud and a rotor fixed to an outer periphery of one of the first propeller and the second propeller radially inward of the stator.

3. a control unit for controlling the operation of the electric motor and the heat engine; The propulsion device according to claim 1 or 2, wherein the control unit operates only the electric motor when the speed generated by the propulsion device is less than a predetermined threshold, and operates the heat engine when the speed is equal to or greater than the threshold.

4. an axially extending fuselage; a first propeller rotatable about the axis; a second propeller provided downstream of the first propeller and rotatable about the axis; an electric motor that rotates and drives one of the first propeller and the second propeller; a heat engine that rotationally drives the other of the first propeller and the second propeller; a control unit that controls the operation of the electric motor and the heat engine; Equipped with The control unit is a propulsion device that operates only the electric motor when the speed of the aircraft is below a predetermined threshold, and operates the heat engine when the speed is above the threshold.

5. 5. The propulsion device according to claim 1, wherein the first propeller and the second propeller rotate in opposite directions.

6. The propulsion device according to claim 1 , wherein the electric motor rotates one of the first propeller and the second propeller using electric power supplied from a battery.

7. a fluid machine body; A fluid machine comprising: a propulsion device according to any one of claims 1 to 6 provided in a main body of the fluid machine.

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