JP2002225796A - Multi-blade axial flow type water jet propelling machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water jet propelling machine reducing the weight of a hull by shortening the whole length of the propelling machine while improving the propelling efficiency of the water jet propelling machine for a ship requiring a large propelling force, and ensuring safety in shallows. SOLUTION: This propelling machine pressurizes water sucked from a sucking port 4a of a sucking casing 4 by an impeller 7 of an impeller casing 6, and jets the pressurized water from a discharging casing toward the rear of a stern, thereby driving a ship 2. A sucking flow passage 4b of the sucking casing 4 is formed to be short. A large number of axial blades 8 having narrow blade widths are implanted on the impeller 7 arranged on the impeller casing 6 to shorten the impeller casing 6, and a large number of guide blades 11 having short flow passages is provided in the discharging casing 10. A discharging port 10a of the discharging casing 10 is submerged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water jet propulsion device for a ship requiring a large propulsion force, and more particularly to an improvement in an axial flow type water jet propulsion device in which the total length of the water jet propulsion device is reduced.

[0002]

2. Description of the Related Art Conventionally, a front impeller and a rear impeller are provided in a pump casing of an axial flow type water jet propulsion device, and a fluid is pressurized to such an extent that cavitation does not occur in the front impeller, and the fluid pressure is further increased by the rear impeller. A propulsion device for improving motive force while preventing cavitation is known, for example, as described in JP-A-5-105190. Then, an impeller is arranged on a rotating shaft suspended from the fountain-like pump casing, the water sucked from the inlet at the center of the pump casing is inverted, and pressurized water is injected into the water from the discharge nozzle to propel the ship. A water jet propulsion type is well known, for example, as described in JP-A-6-286693.

[0003]

However, in the above-described conventional propulsion device having the front impeller and the rear impeller, a large blade area is not required, the blades of the impeller do not overlap, and the propulsion force is low. Although the height can be increased and cavitation can be eliminated, the total length of the water jet propulsion has been increased, and a large water jet propulsion has required an installation space inside the ship. Then, the ship protruded above the water surface behind the stern, and the weight of the ship became heavy, and running in the shallow water had a safety problem. In addition, vertical water jet propulsion machines enable navigation in shallow waters, but the loss when kinetic energy is directly converted to pressure energy increases, and when heavy objects are loaded, back pressure on the discharge side increases. As a result, the operating point may move to the small flow rate side to cause cavitation. SUMMARY OF THE INVENTION An object of the present invention is to provide an axial flow type water jet propulsion device that shortens the overall length of a water jet propulsion device, reduces the weight of a hull, and ensures safety in shallow water while improving propulsion efficiency. I do.

[0004]

SUMMARY OF THE INVENTION The gist of the present invention is that water sucked from a suction port of a suction casing is pressurized by an impeller casing impeller, and pressurized water is jetted rearward from a discharge casing to a ship. In the propulsion device, the suction passage of the suction casing is formed short, a large number of axial flow blades having a small blade width are implanted in an impeller disposed in the impeller casing, and the impeller casing is shortened. Along with pressurizing the inflow water with the axial flow blade, a number of guide blades with a short flow path are arranged inside the discharge casing to convert the swirling flow into a linear flow at a short distance. The rectification effect is improved by dispersing the flow in a number of flow paths of the guide vanes, and the frictional resistance of the high-speed water flow is reduced by the short flow path. Then, the length of the water jet propulsion device is reduced to reduce the weight of the hull, the discharge port of the discharge casing is opened in water, and pressurized water is injected into the water to obtain a large propulsion force. Specifically, the number of impellers of the water jet propulsion machine is eight to twelve. Further, the water jet propulsion device arranged on the bottom of the ship has only the rear end of the discharge casing protruding into the stern water.

[0005] The impeller cone of the impeller disposed in the impeller casing is formed in a conical shape, and is fixed to the leading end on the inflow side protruding inside the suction casing and the front stage of the axial flow blade of the impeller. The starting end of the axial flow vane, which consists of a cylindrical intermediate part and a rounded rear end that secures the rear stage of the axial flow blade and expands the outflow side, and flows between the blade surfaces of the impeller To increase the amount of inflow from the suction casing and reduce the size of the flow path on the rear end side while pressurizing the inflow water with the blade surface of a large number of axial flow blades, thereby accelerating the water flow. . Then, a deflector that is rotatable left and right is pivotally mounted on the discharge casing, and a reverser that enables the opening of the injection port by closing the injection port and moving to the side of the deflector is connected to the deflector. At the same time, an opening bent in the forward direction is provided at the bottom of the deflector, the injection port of the deflector is closed, and pressurized water is injected from the bent opening to enable reverse movement.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A water jet propulsion device according to the present invention is configured as described above, and allows water sucked into a suction casing of a short suction flow path to flow between impeller blades of an impeller casing. Since the pressure is applied to the blade surfaces of the multiple axial flow blades, cavitation at the impeller inlet is prevented, and the water flow is divided between the multiple axial flow blades and pressurized, so that the pressure applied to the water is increased. The guide vanes having a short flow path have low frictional resistance and maintain the discharge pressure of the jet water, thereby improving the propulsion efficiency of the ship. Then, since the pressurized water is injected into the water behind the stern from the discharge port of the submerged discharge casing, a large propulsive force is obtained. In addition, if the reverser is rotated to close the injection port of the deflector, the boat can be made to move backward by injecting pressurized water from the opening at the bottom of the deflector.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to an embodiment. First, FIG. 1 is a schematic side view in which a water jet propulsion device according to the present invention is arranged on a marine vessel. The water jet propulsion device is disposed and is connected to the engine 3. As shown in FIG. 2, in the water jet propulsion device 1, the height of the water jet propulsion device 1 provided on the ship bottom 2b is reduced by forming the suction passage 4b of the suction casing 4 to be short. An impeller 7 disposed in an impeller casing 6 is fitted to a main shaft 5 directly connected to the engine 3, and water sucked from a suction port 4a of the suction casing 4 serving as a short suction flow path 4b is impeller of the impeller casing 6. 7. The water sucked into the suction casing 4 has a lower head up to the impeller 7 and has less pipe resistance to prevent cavitation.
Reference numeral 18 denotes a dust removal screen provided at the suction port 4a of the suction casing 4.

[0008] An impeller 7 arranged in the impeller casing 6
In this example, eight to twelve axial flow blades 8 having a narrow blade width are planted, and the axial flow blades 8 of the impeller 7 have a blade area in which there is little overlap. The impeller casing 6 provided with the impeller 7 having a small blade width is also shortened. As shown in FIG. 2, the impeller 7 disposed on the impeller casing 6 has an impeller cone 9 to which an axial flow blade 8 is fixed, fixed to the main shaft, and the impeller cone 9 is formed in a conical shape. An inflow-side tip portion 9a protruding into the suction casing 4, a cylindrical intermediate portion 9b to which a front portion of the axial flow blade 8 is fixed, and an outflow side to which a rear portion of the axial flow blade 8 is fixed. The flow path on the start end side of the axial flow blade 8 flowing between the blade surfaces of the impeller 7 is widened, and the flow path on the rear end side is reduced. Let me do it. The water that has flowed into the suction casing 4 is guided to the conical tip 9 a of the impeller cone 9, and is guided to the cylindrical intermediate portion 9 b between the axial flow blades 8 of the impeller 7 of the impeller casing 6. The water is accelerated at the vertical rear end portion 9c of the impeller cone 9 whose flow path is reduced while pressurizing the inflow water on the blade surface of a large number of axial flow blades 8 and transported. is there.

As shown in FIGS. 2 and 3, a discharge casing 10 is connected to the impeller casing 6, and a rear end portion of the discharge casing 10 is protruded into stern water to discharge the discharge port of the discharge casing 10. 10a is open to the water.
A guide blade 11 is connected to an inner peripheral surface of the discharge casing 10, and an inner end of the guide blade 11 is connected to an outer peripheral surface of the intermediate casing 12. The number of guide blades 11 is 1 to 1.5 times greater than the number of axial flow blades 8 of the impeller 7, and a number of short flow paths are formed between the guide blades 11.
The intermediate casing 12 is formed concentrically with the expanded outflow end of the rear end portion 9c of the impeller cone 9, and the rear end portion is formed in a conical shape and extends to the discharge port 10a of the discharge casing 10. , The front end of the main shaft 5 is supported. Then, the high-speed swirling flow pressurized by the impeller 7 is subdivided and flown into the inlets of a number of flow paths formed by the guide blade 11, and passed through the flow path having a small contact area to minimize frictional resistance. Thus, the high-speed water flow is linearly rectified without decreasing the flow velocity. The number of the guide blades 11 can be appropriately changed according to the size of the water jet propulsion device 1.

[0010] As shown in FIG.
A deflector 14 is pivotally attached to pins 13 arranged above and below, and the pressurized water rectified by the guide vanes 11 is jetted rearward from the deflector 14 to propel the boat 2, and the boat 2 is rotated left and right by the operation cylinder 15. The direction of travel is switched by moving. In addition, a reverser 17 is pivotally mounted on pins 16 implanted above and below the deflector 14, and the rotating cylinder 20 is operated to close the injection port of the deflector 14 and move to the side of the deflector 14 to eject the fuel. The mouth is opened, the ejection port is closed, and pressurized water is ejected to the bottom of the deflector 14 from the opening 14a bent in the forward direction to move backward.

[0011]

The present invention is configured as described above,
The water jet propulsion device has a water jet propulsion device in which the total length of the water jet propulsion device is shortened to reduce the weight of the hull, and the propulsion efficiency with little head and flow path resistance is improved. That is,
In the case of conventional water jet propulsion systems with front and rear impellers, the friction resistance increases with a propulsion device with a long overall length, and the rectification effect may be reduced with a small number of guide vanes, and the propulsion efficiency of a boat may decrease. Was. In addition, the vertical water jet propulsion device is inefficient due to a large loss when kinetic energy is directly converted to pressure energy, and cavitation may occur. Since the water jet propulsion device was composed of a suction casing having a short path, a pump casing having a large number of axial flow blades having a small blade width, and a short discharge casing having a short flow path having a large number of guide blades. The frictional resistance of the casing is reduced, the discharge pressure of the high-pressure water is maintained, and the propulsion efficiency of the ship is improved. And
The overall length of the water jet propulsion device is shortened, and the weight of the watercraft can be reduced.

Further, the water flow dispersed by a large number of axial flow blades is pressurized on the blade surface, and the swirling flow generated by the impeller is subdivided into a small high-speed water flow by a large number of guide blades to improve the rectification effect. Is injected into the water, so that the discharge pressure of the high-pressure water is maintained and a large thrust is obtained. Then, the impeller cone with the axial flow blade fixed thereto guides the water flow at the conical tip, and flows into the cylindrical intermediate portion where the front stage of the axial flow blade is fixed. Since the water flow is accelerated while compressing the inflowing water on the blade surface and reducing the vertical trailing end flow path in which the rear stage of the blade is fixed, the pressure of the jet water can be increased. Further, since the blade width is short, the manufacture of the impeller becomes easy, and the mounting accuracy of the water jet propulsion device on the ship is improved. Since the discharge casing projecting rearward from the stern is also short, entanglement of the band-like material and contact of driftwood and the like are reduced, and safety is ensured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a ship equipped with a water jet propulsion device according to the present invention.

FIG. 2 is a vertical side view of the water jet propulsion device according to the present invention.

FIG. 3 is a cross-sectional side view of a main part of the water jet propulsion according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water jet propulsion machine 2 Ship 2b Ship bottom 3 Engine 4 Suction casing 4a Suction port 6 Impeller casing 7 Impeller 8 Axial flow blade 9 Impeller cone 9a Tip part 9b Intermediate part 9c Rear end part 10 Discharge casing 10a Discharge port 11 Guide Blade 12 Intermediate casing 14 Deflector 14a Opening 17 Reverser

Claims (5)

[Claims] 1. A suction port (4a) of a suction casing (4).
The water sucked from the impeller casing (6) is pressurized by an impeller (7) of the impeller casing (6), and pressurized water is jetted rearward from the discharge casing (10) to propel the ship (2). The suction passage of 4) is formed short, and a large number of axial flow blades (8) having a small blade width are planted in an impeller (7) provided in the impeller casing (6) to shorten the impeller casing (6). At the same time, a number of guide vanes (1) having a short flow path are provided inside the discharge casing (10).
1), and the discharge port (10a) of the discharge casing (10) is submerged in water. 2. The multi-blade axial flow water jet propulsion device according to claim 1, wherein the number of axial flow blades (8) of said impeller (7) is 8 to 12. 3. The water jet propulsion device (1) disposed on the bottom (2b) of the ship (2) has a rear end of the discharge casing (10) protruding into stern water. The multi-blade axial-flow water jet propulsion device according to claim 1. An impeller cone (9), to which the axial flow blade (8) of the impeller (7) is fixed, is formed in a conical shape and is provided on an inflow side protruding inside the suction casing (4). Tip (9
a), a cylindrical intermediate portion (9b) in which the front stage of the axial flow blade (8) is fastened, and a cylindrical rear portion in which the rear stage of the axial flow blade (8) is fastened and the outflow side is expanded. The flow path on the starting end side of the axial flow blade (8), which is composed of the end portion (9c) and flows between the blade surfaces of the impeller (7), is widened and the flow path on the rear end side is reduced. The multi-blade axial flow water jet propulsion device according to any one of claims 1 to 3, characterized in that: 5. A deflector (14), which is rotatable left and right, is pivotally mounted on the discharge casing (10), and the deflector (14) closes an injection port and the deflector (1).
The reverser (17), which is moved to the side of 4) to open the injection port, is pivotally connected to the deflector (14), and an opening (14a) bent forward is provided at the bottom of the deflector (14). The multi-blade axial flow water jet propulsion device according to any one of claims 1 to 4, wherein: