Ship reduction gear

Abstract

The present invention provides a marine reduction gear that allows for a reduction in the space required for the installation of a rotating electric machine. A marine reduction gear (2) comprises: an input shaft (40) coupled to an output shaft (43) of a motor (11); an output shaft (43) coupled to a propeller shaft (13) that rotates a propeller (14); a gearbox (3) housing an input gear (51) provided on the input shaft (40) and an output gear (55) provided on the output shaft (43), the gearbox (3) holding a first bearing (63) that rotatably supports the output shaft (43); and a rotating electric machine (7) comprising: a central shaft (71) that rotates with the output shaft (43); a rotor (72) attached to the central shaft (71); and a stator (73) surrounding the rotor (72).The gearbox (3) holds the stator (73) and a second bearing (65) which keeps the central shaft (71) of the rotating electric machine (7) rotatable.

Description

[0001] The present invention relates to a ship reduction gear.

[0002] There are cases in which a rotating electric machine is coupled in a ship to a marine reduction gear located between a propeller shaft and a motor which drives a propeller via the propeller shaft, for example to generate electrical current by utilizing excess power from the motor or to assist the motor power by utilizing electrical current (see, for example, JP S62-128 997 U).

[0003] However, in general, a ship's engine room is small and cramped. Therefore, when coupling a rotating electric motor to the ship's reduction gear, a problem arises regarding the space required to install the rotating electric motor.

[0004] In view of the foregoing, it is an object of the present invention to provide a marine reduction gear which enables a reduction of the installation space of the rotating electric machine.

[0005] The problems described above are solved by a marine reduction gear according to claim 1. According to the present invention, this gear comprises: an input shaft coupled to an output shaft of a motor; an output shaft coupled to a propeller shaft that rotates a propeller; a gearbox housing containing an input gear provided on the input shaft and an output gear provided on the output shaft, the gearbox housing holding a first bearing that rotatably supports the output shaft; and a rotating electric machine comprising: a central shaft that rotates together with the output shaft; a rotor attached to the central shaft and a stator surrounding the rotor. The gearbox housing supports the stator and a second bearing that rotatably supports the central shaft of the rotating electric machine.

[0006] In the configuration described above, the rotating electric motor is integrated as a single unit into the gearbox. This reduces the space required for installing the rotating electric motor. Furthermore, since the gearbox serves a dual function as the housing for the rotating electric motor, the weight of the entire system, comprising the ship's reduction gear mechanism and the rotating electric motor, can be reduced.

[0007] The aforementioned marine reduction gear further comprises a lubricating oil pump mounted on or in the gearbox and driven by the input shaft. The lubricating oil pump can circulate lubricating oil so that it flows downwards in the gearbox and supplies it to the second bearing. The lubricating oil supplied to the second bearing can be discharged from the second bearing into the gearbox. In this configuration, the lubricating oil can be supplied to the bearing for the central shaft of the rotating electric machine using the lubricating oil pump that supplies the gears in the gearbox. Furthermore, the lubricating oil supplied to the bearing for the central shaft of the rotating electric machine is discharged from the bearing into the gearbox.This allows the bottom of the gearbox to be used as a lubrication oil reservoir, which is shared by the gearboxes and the rotating electric machine.

[0008] The aforementioned marine reduction gearbox further comprises a coolant pump mounted on or within the gearbox and driven by the input shaft. The coolant pump can supply coolant to the rotating electric machine in such a way that the coolant flows in contact with the stator of the rotating electric machine. In this configuration, the rotating electric machine can be designed more compactly than in a case where the rotating electric machine is cooled by air applied to it. Furthermore, the coolant pump can be driven using the power of the motor or the rotating electric machine, with the power being distributed within the gearbox.

[0009] The coolant pump supplies coolant to the rotating electric machine via a first coolant supply line, and it supplies the coolant to a heat exchanger via a second coolant supply line. The heat exchanger cools the lubricating oil by heat exchange between the lubricating oil and the coolant, where the lubricating oil is either the oil being drawn into the lubricating oil pump or the oil being discharged from the lubricating oil pump. In this configuration, both the cooling of the rotating electric machine and the cooling of the lubricating oil can be achieved using the single coolant pump.

[0010] The present invention enables a reduction in the space required for the installation of the rotating electric machine. Brief description of the drawings Fig. Figure 1 is a top view showing a schematic configuration of a ship reduction gear according to an embodiment of the present invention. Fig. Figure 2 is a front view of the ship's reduction gear according to Fig. 1. Fig. Figure 3 is a perspective sectional view showing a rotating electric machine.

[0011] Fig. 1 and Fig. Figure 2 shows a marine reduction gear 2 according to an embodiment of the present invention. The marine reduction gear 2 is arranged together with a motor 11 in the engine room of a ship.

[0012] More precisely, the ship's reduction gear 2 comprises: an input shaft 40 coupled to an output shaft 12 of the motor 11; and an output shaft 43 coupled to a propeller shaft 13, which rotates a propeller 14. For the sake of clarity, the side of the output shaft 43 in its axial direction on which the propeller shaft 13 is located will be referred to below as the aft or stern side, and the other side of the output shaft 43 in its axial direction will be referred to as the forward or bow side.

[0013] In the present embodiment, the engine 11 is arranged aft of the ship's reduction gear 2. Alternatively, however, the engine 11 can be arranged forward of the ship's reduction gear 2. The engine 11 can be a gas turbine engine or a two-stroke or four-stroke piston engine.

[0014] An input gear 51 is provided on the input shaft 40, and an output gear 55 is provided on the output shaft 43. The input gear 51 and the output gear 55 can mesh directly or via (one or more) further gears. The input gear 51 and the output gear 55 are housed in a gearbox 3.

[0015] The input shaft 40 projects rearward from the gearbox 3, parallel to the output shaft 43, and is coupled to the output shaft 12 of the motor 11 by a flange coupling. Similarly, the output shaft 43 projects rearward from the gearbox 3 and is coupled to the propeller shaft 13 by a flange coupling.

[0016] In the present embodiment, the input shaft 40 is divided into: a front part 42, on which the input gear 51 is provided; and a rear part 41, which enters the gearbox 3. The rear part 41 and the front part 42 of the input shaft 40 are coupled to each other via a coupling 21. Alternatively, however, the input shaft 40 can be a single integrated component, and the input shaft 40 can be coupled to the output shaft 12 of the motor 11 outside the gearbox 3 via the coupling 21.

[0017] The gearbox 3 holds a bearing 61 and a bearing 62, wherein the bearing 61 rotatably holds the rear part 41 of the input shaft 40 and the bearings 62 rotatably hold the front part 42 of the input shaft 40. The gearbox 3 also holds bearings 63, which rotatably hold the output shaft 43 (the bearings 63 correspond to a first bearing according to the present invention).

[0018] In the present embodiment, a rotating electric machine 7 is integrally integrated into the gearbox 3, and a lubricating oil pump 15 and a coolant pump 16 are mounted on or in the gearbox 3.

[0019] The lubricating oil pump 15 and the coolant pump 16 are driven by the input shaft 40. More precisely, the front part 42 of the input shaft 40 is provided with a drive gear 52, and the rotating shaft of the lubricating oil pump 15 and the rotating shaft of the coolant pump 16 are each provided with a driven gear 53 and a driven gear 54. The drive gear 52 can engage directly with the driven gears 53 and 54 or via one or more other gears. The drive gear 52 and the driven gears 53 and 54 are also housed in the gearbox 3. The functions of the lubricating oil pump 15 and the coolant pump 16 are described below.

[0020] In the present embodiment, the rotating electric machine 7 functions as both a power generator and an electric motor. When the rotating electric machine 7 functions as a power generator, the clutch 21 is engaged. When the rotating electric machine 7 functions as an electric motor, with the clutch 21 engaged, the rotating electric machine 7 assists the power of the motor 11, and with the clutch 21 disengaged, the screw 14 is turned exclusively by the rotating electric machine 7. Alternatively, the rotating electric machine 7 can function only as a power generator or only as an electric motor. It should be noted that a clutch 22, as described below, is engaged both when the rotating electric machine 7 functions as a power generator and when it functions as an electric motor.

[0021] The rotating electric machine 7 comprises: a central shaft 71, which rotates together with the output shaft 43 and extends in a front-to-rear direction; a rotor 72, which is attached to the central shaft 71; and a stator 73, which surrounds the rotor 72. In the present embodiment, a first and a second transmission shaft 44 and 45 are provided between the central shaft 71 and the output shaft 43, parallel to these. The second transmission shaft 45 is arranged forward of the central shaft 71, and the first transmission shaft 44 is arranged laterally to the central shaft 71 of the rotating electric machine 7 and to the second transmission shaft 45.

[0022] The first transmission shaft 44 is provided with a first transmission gear 56, which engages directly or via (one or more) further gears with the output gear 55, and a second transmission gear 57, which is arranged forward of the first transmission gear 56. The gearbox 3 holds bearings 64, which allow the first transmission shaft 44 to rotate.

[0023] The second transmission shaft 45 is equipped with an input / output gear 58 that engages directly or via one or more further gears with the second transmission gear 57. The second transmission shaft 45 is coupled to the central shaft 71 of the rotating electric machine 7 via the clutch 22. If a malfunction of the rotating electric machine 7 occurs, the clutch 22 is deactivated (disengaged) to prevent the output shaft 43 from becoming immobilized due to the malfunction of the rotating electric machine 7. It should be noted that the clutch 22 can be deactivated when the screw 14 is turned using only the motor 11, in order to bring the rotating electric machine 7 to a standstill and reduce the mechanical loss caused by the rotating electric machine 7.

[0024] Alternatively, the second transmission shaft 45 can be arranged rearward of the rotating electric machine 7. Furthermore, the first transmission shaft 44, the second transmission shaft 45, and the coupling 22 can alternatively be omitted, and the input / output gear 58 can be provided on the central shaft 71 of the rotating electric machine 7 such that the input / output gear 58 engages directly or via (one or more) further gears with the output gear 55.

[0025] The gearbox 3 holds bearings 65, which rotatably support the central shaft 71 of the rotating electric machine 7 (the bearings 65 correspond to a second bearing according to the present invention). The gearbox 3 also holds the stator 73 of the rotating electric machine 7.

[0026] As in Fig. As shown in Figure 2, the gearbox 3 comprises: a main structural body 31 in which the output gear 55 is arranged; and a first cover 36 and a second cover 37, each forming an enclosed space together with the main structural body 31. The input gear 51 is arranged in the enclosed space formed by the first cover 36 and the main structural body 31, and the rotating electric machine 7 and the input / output gear 58 are arranged in the space formed by the second cover 37 and the main structural body 31.

[0027] The main structural body 31 comprises a rear wall 31a and a front wall 31b, which are parallel to each other (see Fig. 1) The output shaft 43 penetrates the rear wall 31a and the front wall 31b. The bearings 63, which hold the output shaft 43 rotatably, are held by the rear wall 31a and the front wall 31b via bearing bases (not shown) mounted on the rear and front walls 31a and 31b.

[0028] In the present embodiment, as in Fig. Figure 3 shows the bearing 65, which rotatably holds the rear end of the central shaft 71 of the rotating electric machine 7, by means of a bearing base half-body 34 mounted on the rear wall 31a and a bearing base half-body 34 mounted on the second cover 37 (the bearing base half-body 34 of the second cover 37 not shown) from the rear wall 31a of the main structural body 31 and the second cover 37. It should be noted that Fig. Figure 3 is a perspective sectional view showing the rotating electric machine 7 in a state where the second cover 37 is removed.

[0029] In the main structural body 31, a partition 33 is provided at a position corresponding to the front end of the central shaft 71 of the rotating electric machine 7. A bearing base half-body 35 is integrally formed with the partition 33. Similarly, a bearing base half-body 35 is integrally formed with the second cover 37 (the bearing base half-body 35 of the second cover 37 is not shown). The bearing 65, which rotatably holds the front end of the central shaft 71 of the rotating electric machine 7, is held by the partition 33 and the second cover 37 via these bearing base half-bodies 35.

[0030] In the present embodiment, a permanent magnet is installed in the rotor 72 of the rotating electric machine 7, and a coil 74 is integrated into the stator 73. However, the configuration of the rotating electric machine 7 is not limited to this. Alternatively, the coil 74 can be integrated into the rotor 72, and the permanent magnet can be integrated into the stator 73. Furthermore, in the present embodiment, the stator 73 is covered with a protective cover 75. A channel through which a coolant flows is formed inside the protective cover 75 or between the protective cover 75 and the stator 73. The channel is described below. The main structural body 31 and the second cover 37 are provided with several partitions 32 that hold the stator 73 of the rotating electric machine 7 over the protective cover 75 (the partitions 32 of the second cover 37 are not shown).

[0031] Again according to Fig.2 The aforementioned lubricating oil pump 15 circulates the lubricating oil so that the lubricating oil flows downwards in the gearbox 3. The lubricating oil pump 15 supplies the lubricating oil not only to the bearings 61 to 64 intended for the input shaft 40, the output shaft 43 and the first transmission shaft 44, but also to the bearings 65 intended for the central shaft 71 of the rotating electric machine 7.

[0032] More precisely, the base of the main structural body 31 of the gearbox 3 is connected to the intake opening of the lubricating oil pump 15 via a collecting line 81, a lubricating oil tank 17, a first suction line 82, a heat exchanger 18, and a second suction line 83. The lubricating oil flowing downwards in the gearbox 3 is collected by the base of the main structural body 31 and conveyed via the collecting line 81 to the lubricating oil tank 17. The lubricating oil stored in the lubricating oil tank 17 is conveyed via the first suction line 82 to the heat exchanger 18. After cooling in the heat exchanger 18, the lubricating oil is drawn into the lubricating oil pump 15 via the second suction line 83.

[0033] A main drain line 84 extends from the outlet of the lubricating oil pump 15 to various gears. A first branch line 85 and a second branch line 86 branch off from the main drain line 84. The first branch line 85 is connected to bearings 61 to 64, and the second branch line 86 is connected to bearing 65. The lubricating oil delivered by the lubricating oil pump 15 is supplied to the various gears via the main drain line 84, and it is also supplied to bearings 61 to 65 via the first branch line 85 and the second branch line 86. The lubricating oil supplied to bearings 61 to 65 is discharged from bearings 61 to 65 into the main structural body 31 of the gearbox 3.

[0034] A coolant is supplied from outside the engine room to the coolant pump 16 via an inlet line 91. The coolant is, for example, seawater. The coolant pump 16 supplies the coolant to the rotating electric machine 7 (more precisely, to the aforementioned channel formed in the protective casing 75 or between the protective casing 75 and the stator 73) via a first coolant supply line 92, and it supplies the coolant to the heat exchanger 18 via a second coolant supply line 93. An upstream section of the first coolant supply line 92 and an upstream section of the second coolant supply line 93 form a single common channel.

[0035] The heat exchanger 18 cools the lubricating oil being drawn into the lubricating oil pump 15 by heat exchange between the coolant flowing into the heat exchanger 18 from the second coolant supply line 93 and the lubricating oil flowing into the heat exchanger 18 from the first suction line 82. The coolant flowing from the heat exchanger 18 is discharged from the engine room to the outside via an outlet line 95. Alternatively, the heat exchanger 18 can be located downstream of the lubricating oil pump 15, and the lubricating oil delivered by the lubricating oil pump 15 can be cooled by the heat exchanger 18.

[0036] The coolant is supplied to the rotating electric machine 7 in such a way that it flows into contact with the stator 73. If the aforementioned channel is located inside the protective casing 75, the coolant indirectly comes into contact with the stator 73 via the partitions that form part of the casing 75. Conversely, if the aforementioned channel is located between the protective casing 75 and the stator 73, the coolant comes into direct contact with the stator 73. The coolant supplied to the rotating electric machine 7 is discharged from the machine compartment to the outside via the outlet line 95.

[0037] As described above, in the present embodiment of the marine reduction gear 2, the rotating electric machine 7 is integrally integrated into the gearbox 3. This allows for a reduction in the space required for installing the rotating electric machine 7. Furthermore, since the gearbox 3 serves a dual function as the housing for the rotating electric machine 7, the weight of the entire system, comprising the marine reduction gear mechanism (the gearbox 3 and the gear train housed therein) and the rotating electric machine 7, can be reduced.

[0038] The rotating electric machine 7 can be made compact by setting its rated speed to a high value, even in cases where the rotating electric machine 7 is a powerful machine. Such a compact rotating electric machine 7 can easily be integrated into the gearbox 3.

[0039] Since the rotating electric machine 7 is integrated into the gearbox 3, the input / output gear 58 can be located close to the rotating electric machine 7. Therefore, compared to a conventional configuration where the rotating electric machine is coupled to the marine reduction gearbox, for example by a flange coupling, the distance between the rotating electric machine 7 and the input / output gear 58 can be reduced, thus suppressing vibration of the central shaft 71 of the rotating electric machine 7.

[0040] In the present embodiment, the lubricating oil can be supplied to the bearings 65 for the central shaft 71 of the rotating electric machine 7 using the lubricating oil pump 15, which supplies the gears in the gearbox 3 with the lubricating oil. Furthermore, the lubricating oil supplied to the bearings 65 is discharged from the bearings 65 into the main structural body 31 of the gearbox 3. Thus, the base of the main structural body 31 can be used as a lubricating oil reservoir, which is shared by the gears and the rotating electric machine 7.

[0041] In the present embodiment, the coolant is supplied to the rotating electric machine 7 by the coolant pump 16. Accordingly, the rotating electric machine 7 can be designed more compactly than in a case where the rotating electric machine 7 is cooled by air applied to it. Furthermore, the coolant pump 16 can be driven using the power of the motor 11 or the rotating electric machine 7, with the power being distributed in the gearbox 3.

[0042] Furthermore, since the coolant pump 16 also supplies the coolant to the heat exchanger 18, both the cooling of the rotating electric machine 7 and the cooling of the lubricating oil can be carried out using the single coolant pump 16.

[0043] The present invention is not limited to the embodiment described above. Various modifications can be made without departing from the concept of the present invention.

[0044] For example, it is not necessary for both the lubricating oil pump 15 and the coolant pump 16, or either of them, to be mounted on the marine reduction gear 2. Alternatively, either the lubricating oil pump 15 or the coolant pump 16, or both, can be installed separately from the marine reduction gear 2. The second coolant supply line 93 can be omitted, and the heat exchanger 18 can cool the lubricating oil by heat exchange between the lubricating oil and air.

[0045] It is not necessary for the coolant to be used to cool the rotating electric machine 7. If, for example, the temperature of the lubricating oil is suitable for cooling the rotating electric machine 7, the lubricating oil can be supplied to the rotating electric machine 7 by the lubricating oil pump 15, and the rotating electric machine 7 can be cooled using the lubricating oil.

[0046] The number of rotating electric machines 7 integrated as a single unit into the gearbox 3 can be one or more. List of reference symbols 2 ship reduction gears 3 gearboxes 7 rotating electric machine 11 Engine 12 Output shaft 13 Screw shaft 14 screw 15 Lubricating oil pump 16 Coolant pump 17 Lubricating oil tank 18 heat exchangers 21, 22 Clutch 31 main structural body 31a rear wall 31b front wall 32, 33 Partition wall 34, 35 Bearing base half-body 36 first cover 37 second cover 40 Input shaft 41 rear part of the input shaft 42 front part of the input shaft 43 Output shaft 44 first transmission wave 45 second transmission wave 51 Input gear 52 Drive wheel 53, 54 driven gear 55 Output gear 56 first transmission gear 57 second transmission gear 58 Input / Output Gear 61 to 65 bearings 71 Central shaft 72 Rotor 73 Stator 74 coil 75 Protective cover 81 Collective line 82 first suction line 83 second suction line 84 Main drain line 85 first branch management 86 second branch management 91 Introduction line 92 first coolant supply line 93 second coolant supply line 95 Outlet pipe

Claims

[1] Ship reduction gear (2) comprising: an input shaft (40) coupled to a first output shaft (12) which is an output shaft of a motor (11); a second output shaft (43) coupled to a screw shaft (13) which rotates a screw (14); a gearbox (3) in which an input gear (51) provided on the input shaft (40) and an output gear (55) provided on the second output shaft (43) are housed, wherein the gearbox (3) holds a first bearing (63) which holds the second output shaft (43) rotatably; and a rotating electric machine (7) comprising: a central shaft (71) which rotates together with the second output shaft (43); a rotor (72) attached to the central shaft (71); and a stator (73) surrounding the rotor (72), wherein the gearbox (3) holds the stator (73) and a second bearing (65) which keeps the central shaft (71) of the rotating electric machine (7) rotatable; wherein the ship reduction gear (2) further comprises: a lubricating oil pump (15) which is mounted on the gearbox (3) and is driven by the input shaft (40), wherein the lubricating oil pump (15) circulates lubricating oil in such a way that the lubricating oil flows downwards in the gearbox (3) and supplies the lubricating oil to the second bearing (65), and the lubricating oil supplied to the second bearing (65) is discharged from the second bearing (65) into the gearbox (3); and a coolant pump (16) which is mounted on the gearbox (3) and is driven by the input shaft (40), wherein the coolant pump (16) supplies a coolant to the rotating electric machine (7) in such a way that the coolant flows into contact with the stator (73) of the rotating electric machine (7), wherein the coolant pump (16) supplies the coolant to the rotating electric machine (7) via a first coolant supply line (92) and supplies the coolant to a heat exchanger (18) via a second coolant supply line (93), and the heat exchanger (18) cools the lubricating oil by heat exchange between the lubricating oil and the coolant, wherein the lubricating oil is the lubricating oil to be drawn into the lubricating oil pump (15) or the lubricating oil that has been discharged from the lubricating oil pump (15).

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