JPH1170894A - Shaft structure of water jet propeller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the necessity of providing a thrust bearing within a connecting part by providing a reduction gear between a prime motor and the drive shaft of an impeller, and receiving the thrust load generated in the impeller by a thrust bearing included in the reduction gear. SOLUTION: The output shaft 5a of a main engine 5 is connected to the input shaft 4d of a reduction gear 4 by a bolt piercing the flanges at both the shaft ends, and the output shaft 4c of the reduction gear 4 is connected to a drive shaft 3 in rigid state by a bolt piercing the flanges at both the shaft ends. Thus, a thrust load and a radial load are directly transmitted from the drive shaft 3 of an impeller 2 to the output shaft 4c of the reduction gear 4. The thrust load is received by a thrust bearing 4a built in the reduction gear 4. According to this structure, only a radial bearing 15a can be provided within a connecting part 21 without requiring the integration of a thrust bearing into the connecting part 21. Thus, the frequency of maintenance and replacement of the radial bearing 15a can be reduced by adapting a one having a large size and high durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft structure of a water jet propulsion device used for a ship.

[0002]

2. Description of the Related Art As a shaft structure of a conventional water jet propulsion machine, for example, there is one shown in FIG.
In FIG. 4, reference numeral 111 denotes an intake port formed in a ship bottom 110, reference numeral 113 denotes a nozzle provided at a stern end 112,
Is an impeller, 103 is a drive shaft of the impeller 102, 104
Is a reduction gear, and 105 is a main engine. An intermediate shaft 153 is interposed between the output shaft 104c of the speed reducer 104 and the drive shaft 103, the drive shaft 103 and the intermediate shaft 153 are connected by a flexible coupling 150, and the intermediate shaft 153 and the output shaft 104c are They are connected by bolts (not shown) that penetrate the end flanges. The output shaft 105a of the main engine 105 and the input shaft 104d of the speed reducer 104 are also connected by bolts (not shown) penetrating flanges at both shaft ends. In addition, 120 is a stationary blade, 121 is a coupling portion that couples the plurality of stationary blades 120 on the axial center side, 130 is a sealing device, 151 is an intermediate bearing for supporting the intermediate shaft 153,
152 is a radial bearing for supporting the drive shaft 103.

A water jet propulsion device is mainly used for a high-speed boat, but a high-speed engine or a gas turbine is often used as the main engine 105 because of a demand for downsizing and weight reduction in the design of the high-speed boat. For this reason, it is necessary.

When the main engine 105 is driven and the impeller 102 is driven to rotate and the boat is propelled, the impeller 1
02 and a radial load on the drive shaft 103. This thrust load is
The radial load on the stern side of the drive shaft 103 is received by the radial rolling bearing 115, and the radial load on the bow side of the drive shaft 103 is received by the radial bearing 152.
Since the flexible coupling 150 is interposed, these thrust loads and radial loads are reduced by the speed reducer 10.
4 is not transmitted. 117 is the bearing 11
Reference numeral 119 denotes an oil seal for preventing lubricating oil from flowing out of the bearing chamber 118 while preventing seawater from entering the bearing chamber 118.

In FIG. 4, C is a clearance between the tip of the impeller 102 and the inner surface of the housing 106. The clearance C is desirably as small as possible from the viewpoint of improving propulsion efficiency. However, since the impeller 102 shown in FIG. 4 is a diagonal flow type, the axial position of the impeller 102 changes due to expansion and contraction due to thermal expansion of the shaft system structure. Then, the clearance C changes, and in the worst case, the housing 106 and the impeller 102 interfere with each other. The flexible coupling 150 is moved from the main engine 105 to the intermediate shaft 15.
It also plays a role of absorbing expansion and contraction due to temperature expansion of the shaft system up to 3 and preventing the influence of expansion and contraction from reaching the axial position of the impeller 102.

When an axial-flow type impeller is employed, the shaft system structure is basically the same as that shown in FIG.

[0007]

However, in the shaft system structure shown in FIG. 4, a radial rolling bearing 115 and a thrust rolling bearing 116 are incorporated in a limited space inside the coupling portion 121. Therefore, both bearings 115 and 116 must be small. Therefore, the dual bearings 115 and 116
In both cases, a product having high durability and a long product life cannot be adopted, and it is necessary to frequently perform maintenance and replacement. The bearings 115 and 116 shown in FIG. 4 are rolling bearings. In particular, rolling bearings are parts having a design life due to fatigue strength and need to be replaced at certain operation intervals.
This replacement operation must be performed more frequently as the dimensions of the bearing are smaller. In any case, disassembly / assembly work is required for replacement based on the life, and time and cost are increased.

As can be seen from FIG. 4, a flexible coupling 150 and a radial bearing 152
Therefore, there is a limit in reducing the length L of the shaft system. In high-speed boats, there is a strong demand for reducing the weight of the boat, but the inability to reduce the length L of the shaft system hinders the reduction in size and weight of the shaft system.

[0009]

SUMMARY OF THE INVENTION A shaft structure of a water jet propulsion device according to the present application includes an impeller of an axial flow type, and a reduction gear is interposed between a prime mover and a drive shaft of the impeller to generate the impeller. The thrust load is received by a thrust bearing built into the reduction gear. For this reason,
There is no need to provide a thrust bearing in a joint that couples a plurality of vanes on the axial center side. Also, there is no need to interpose a flexible coupling between the drive shaft of the impeller and the speed reducer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A shaft structure of a water jet propulsion device according to the present invention is configured such that water taken in from an intake opening formed at the bottom of a ship is rotated by an axial impeller with the driving force of a motor. In a shaft structure of a water jet propulsion device that obtains thrust by jetting from a stern nozzle by pressurizing, a speed reducer is interposed between a prime mover and a drive shaft of the impeller, and thrust generated in the impeller is generated. The load is received by a thrust bearing built in the speed reducer. With such a configuration, it is not necessary to provide a thrust bearing inside the coupling portion that couples the plurality of stationary blades on the axial center side, and it is possible to provide only the radial bearing inside the coupling portion. For this reason, it is possible to use a radial bearing having a large durability and a long product life as a radial bearing. As a result, the frequency of maintenance and replacement of the radial bearing can be reduced. Also,
Since there is no need to interpose a flexible coupling between the drive shaft of the impeller and the speed reducer, the overall length of the shaft system structure can be reduced.

Further, in the above-mentioned shaft system structure of the water jet propulsion device, if a radial load generated on the bow side of the drive shaft of the impeller is received by a radial bearing built in the speed reducer, the drive shaft of the impeller Therefore, there is no need to separately provide a radial bearing for supporting the bow side, and the length of the shaft system can be further reduced.

In the above-mentioned shaft structure of the water jet propulsion device, a thrust load generated on the impeller is received by a thrust bearing built in the reduction gear, or a radial generated on a bow side of a drive shaft of the impeller. The drive shaft of the impeller and the output shaft of the reduction gear may be rigidly connected so that the load is received by the radial bearing built in the reduction gear.

In the above-mentioned shaft structure of the water jet propulsion device, the radial bearing for receiving the radial load generated on the stern side of the drive shaft of the impeller may be a radial bearing for circulating water or oil. Good.
The radial bearing by water circulation or oil circulation keeps the working surface in non-contact, so that the working surface is less worn and the product life is longer. Therefore, it is more effective to reduce the frequency of maintenance and replacement of the radial bearing.

[0014]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a shaft system structure showing an embodiment of a shaft system structure of a water jet propulsion device according to the present application. 2 is an impeller, 3 is a drive shaft of the impeller 2,
4 is a speed reducer, 5 is a main engine as a motor, 6 is a housing constituting a pump room, 10 is a boat bottom, 11 is a water intake opening formed in the boat bottom 10, 12 is a stern end, and 13 is a stern end 1.
2 is a nozzle, 20 is a stationary blade, and 21 is a coupling portion that couples the plurality of stationary blades 20 on the axial center side.

The impeller 2 is of an axial flow type. Generally, a high-speed engine, a gas turbine, or the like is used as the main engine 5. Output shaft 5a of main engine 5 and input shaft 4d of reduction gear 4
Are connected by bolts (not shown) penetrating the flanges at both ends of the shaft. The output shaft 4c of the reduction gear 4 and the drive shaft 3 are bolts (not shown) penetrating the flanges at both the shaft ends.
Are connected in a rigid state. Therefore, the thrust load and the radial load are directly transmitted from the drive shaft 3 of the impeller 2 to the output shaft 4c of the reduction gear 4. A thrust bearing 4 a and a radial bearing 4 b are built in the reduction gear 4. Further, a water circulation type radial bearing 15a is incorporated in the coupling portion 21. The seal device 30 provided on the main engine 5 side of the housing 6 is for preventing water taken in from the water intake port 11 by the water jet propulsion machine from leaking to the engine room side.

When the main engine 5 is driven and driven, the impeller 2 is driven to rotate at the rotation speed reduced by the speed reducer 4. As a result, the water taken in from the water intake 11 is jetted from the nozzle 13 in a pressurized state, and the boat obtains propulsion by the reaction from the jetted water. When the water jet propulsion device is generating the propulsive force in this way, a thrust load is generated on the impeller 2. This thrust load is applied to the reduction gear 4 rigidly connected to the drive shaft 3.
Is directly transmitted to the output shaft 4c and received by the thrust bearing 4a. The thrust bearing 4a has a load resistance enough to withstand a thrust load generated by the impeller 2. Also, a radial load is generated on the drive shaft 3,
The radial load on the bow side is directly transmitted to the output shaft 4c of the speed reducer 4 rigidly connected to the drive shaft 3, and the radial bearing 4b
Received by The radial bearing 4 b has a load resistance enough to withstand a radial load on the bow side of the drive shaft 3. The radial load on the stern side of the drive shaft 3 is
It is received by the radial bearing 15a.

In this structure, it is not necessary to incorporate a thrust bearing inside the connecting portion 21, and only the radial bearing 15a needs to be built inside the connecting portion 21. The internal space of the coupling portion 21 is limited, and the size of the bearing that can be incorporated therein is limited. However, since there is no need to incorporate a thrust bearing, the radial bearing 15a is large and durable. Highly productive and long product life can be adopted. As a result, the radial bearing 15a
Maintenance and replacement frequency can be reduced. As described above, the radial bearing 15a is of a water circulation type, in which water circulates. In FIG. 1, arrows A and B show the flow of the circulating water.

Although the drive shaft 3 and the output shaft 4c are connected without using a flexible coupling, the reduction gear 4 can be omitted by omitting the flexible coupling.
The thrust load and the radial load generated in the impeller 2 and the drive shaft 3 can be received by the thrust bearing 4a and the radial bearing 4b incorporated in the motor. Thus, by omitting the flexible coupling, the shaft system length L is reduced. When the length L of the shaft system is reduced, the engine room can be made smaller, and thus, for example, the cabin of the ship can be made wider. In addition, the weight of the shaft structure is reduced by reducing the length L of the shaft system. Also, general flexible couplings have grease sealed inside for lubrication and require regular work for their maintenance.However, by eliminating the flexible coupling from the shaft structure, this maintenance is also It becomes unnecessary.

Further, since the radial load on the bow side of the drive shaft 3 is received by the radial bearing 4b, a radial bearing for supporting the bow side of the drive shaft 3 is unnecessary, and in the embodiment of FIG. This is not provided. Therefore, the shaft system length L is further reduced.

Further, since the flexible coupling and the radial bearing for supporting the bow side of the drive shaft 3 are omitted, the number of parts is reduced, and the manufacturing cost of the shaft system structure is also reduced.

Since the output shaft 4c of the speed reducer 4 is directly connected to the drive shaft 3 without using a flexible coupling, the axial position of the impeller 2 changes due to expansion and contraction due to temperature expansion of the entire shaft system structure. become. The amount of expansion and contraction is large due to the temperature expansion of the entire shaft system. Therefore, the shape of the impeller 2 must be of the axial flow type. This is because if the impeller is of a diagonal flow type, the axial position of the impeller greatly changes, so that the clearance between the inner surface of the housing 6 and the tip of the impeller greatly changes, thereby lowering the propulsion efficiency of the water jet propulsion device and the housing 6 and the impeller. This is because it causes interference. In the case of the axial flow type, a change in the axial position of the impeller does not affect the clearance C.

FIG. 2 shows another embodiment of the shaft structure of the water jet propulsion device according to the present invention. FIG.
In this embodiment, the water circulating type radial bearing 15a is incorporated in the connecting portion 21, but in the embodiment shown in FIG. 2, a radial rolling bearing 15b is incorporated. Although this shaft system is provided with a pump device for feeding lubricating oil to the bearing 15b, it is omitted from the drawing. Reference numeral 19 denotes an oil seal for preventing seawater from entering the bearing room 18 and preventing lubricating oil from flowing out of the bearing room 18. Other points are the same as those of the embodiment of FIG.

As shown in the embodiment of FIG.
A rolling bearing may be incorporated therein, but this may be an oil circulation type bearing. Generally, a water circulation type or oil circulation type bearing has no oil-water film due to a wedge effect, so that the working surfaces do not come into contact with each other, and a long life can be expected.

FIG. 3 shows still another embodiment of the shaft structure of the water jet propulsion device according to the present application. In this embodiment, the drive shaft 3 is supported by a radial bearing 52 near the end on the bow side. Generally, the main engine 5 has a large weight, and its installation position greatly affects the position of the center of gravity of the ship. Where to set the center of gravity in ship design is an important factor. If it is desired to install the main engine 5 more forward (on the bow side) due to the design of the center of gravity, it is necessary to lengthen the drive shaft 3 or move the drive shaft 3 between the drive shaft 3 and the output shaft 4c. An intermediate shaft may be interposed. In such a case, it becomes difficult to support the drive shaft 3 only by the radial bearing 4b built in the reduction gear 4, and therefore, as in this embodiment, the radial bearing 5
2 should be provided. Also in this embodiment, the drive shaft 3 and the output shaft 4c are rigidly connected without interposing a flexible coupling, and a thrust load generated by the impeller 2 is received by a thrust bearing 4a built in the reduction gear 4. Therefore, no thrust bearing is incorporated inside the coupling portion 21.

[0026]

The present invention is embodied in the form described above, and has the following effects.

(1) It is not necessary to provide a thrust bearing inside a joint that couples a plurality of stationary blades on the axial center side, and it is possible to provide only a radial bearing inside the joint. For this reason, as a radial bearing that receives a radial load on the stern side of the drive shaft of the impeller, a large-sized, durable, long-life product can be adopted.If such a radial bearing is adopted, The frequency of maintenance and replacement can be reduced.

(2) Since there is no need to interpose a flexible coupling between the drive shaft of the impeller and the speed reducer, the length of the shaft system can be shortened. Ring maintenance work is also unnecessary.

(3) If the radial load generated on the bow side of the drive shaft of the impeller is received by the radial bearing built in the reduction gear, a radial bearing for supporting the bow side of the drive shaft of the impeller is separately provided. This eliminates the need and further reduces the length of the shaft system.

(4) If the radial bearing that receives the radial load generated on the stern side of the drive shaft of the impeller is a radial bearing that circulates water or oil, the frequency of maintenance and replacement of the radial bearing can be further reduced. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view of a shaft system structure showing an embodiment of a shaft system structure of a water jet propulsion device according to the present application.

FIG. 2 is a diagram showing another embodiment of the shaft system structure of the water jet propulsion device according to the present application.

FIG. 3 is a view showing still another embodiment of the shaft system structure of the water jet propulsion device according to the present application.

FIG. 4 is a diagram showing a shaft structure of a conventional water jet propulsion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Impeller 3 ... Drive shaft 4 ... Reduction gear 4a ... Thrust bearing 4b ... Radial bearing 4c ... Output shaft 4d ... Input shaft 5 ... Main engine 5a ... Output shaft 6 ... Housing 10 ... Ship bottom 11 ... Water intake 12 ... Stern end 13 ... Nozzle 15a ... Radial bearing 15b ... Radial rolling bearing 18 ... Bearing chamber 19 ... Oil seal 20 ... Static vane 21 ... Coupling part 52 ... Radial bearing C ... Clearance L ... Shaft system length

Claims (4)

[Claims] 1. The water taken in from an intake opening formed at the bottom of a ship is pressurized by rotating an impeller of an axial flow type by a driving force of a motor, and is jetted from a nozzle at a stern to generate thrust. In the shaft structure of the obtained water jet propulsion device, a speed reducer is interposed between the prime mover and the drive shaft of the impeller, so that a thrust load generated in the impeller is received by a thrust bearing built in the speed reducer. The shaft structure of the water jet thruster. 2. The shaft structure of a water jet propulsion device according to claim 1, wherein a radial load generated on a bow side of a drive shaft of said impeller is received by a radial bearing built in said speed reducer. 3. The drive shaft of the impeller and the output shaft of the speed reducer are rigidly connected to each other.
Or a shaft structure of the water jet propulsion device according to 2. 4. The radial bearing which receives a radial load generated on the stern side of the drive shaft of the impeller is a radial bearing which circulates water or oil. 2. The shaft structure of the water jet propulsion device according to 1.