JPH061194U - Reverse thrust reduction device for water injection propulsion device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a reverse thrust reduction preventing device for a water injection propulsion device in which jet water does not increase the suction resistance of the pump during reverse travel. A water jet propulsion device having a tubular nozzle tube 1 connected to an outlet of a pump P, an inner flap 2 provided inside the nozzle tube 1 and an outer flap 3 provided at a lower portion of the water jet propulsion apparatus. On the inner side of the flap 3, a flow dividing member 4 that expands from the base portion 3a toward the jet water outlet side end portion 3b is formed to project, and a jet water passage 5 that is separated in two directions is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for preventing a thrust from decreasing when moving backward in a water jet propulsion device for a ship.

[0002]

[Prior art]

 As a technique of a conventional water jet propulsion device for a marine vessel, there is a disclosure described in Japanese Patent Publication No. 3-29638. In this water injection propulsion device, as shown in the side sectional view of FIG. 7, a cylindrical nozzle pipe 51 is connected to the outlet of the pump P, the inside of the nozzle pipe 51 is an inner flap 52, and the lower portion is an outer flap 53. Is provided.

FIG. 7 shows a reverse state of the water jet propulsion device, in which the inner flap 52 is raised and the outer flap 53 is lowered. Therefore, the jet water from the outlet of the pump P hits the inner flap 52 and is bent downward, and the jet water that comes out of the opening 57 is bent rightward and downward by the outer flap 53 to be discharged. Go backwards towards you. Numerals 54 and 55 are levers and links for opening and closing the inner flap 52 and the outer flap 53, and 56 is a swivel axis around which the inner flap 52 and the outer flap 53 rotate. Further, 52a provided on the inner flap 52 and 53a provided on the outer flap 53 are ribs provided on the edges of both flaps to form the inner flap 52 and the outer flap 53 in a bucket shape. It is a bandage.

[0004]

[Problems to be solved by the device]

 However, in the above-mentioned conventional technique, the jet water discharged from the outer flap 53 flows into the range indicated by the one-dot chain line J below the hull H as shown in the side view of the hull H shown in FIG. The lower part of the suction port Pa will be covered.

Originally, in the marine water jet propulsion device, the shape of the suction passage from the suction port Pa to the pump P via the suction passage Pb is such that the water flow toward the hull H from the right side in the drawing. The suction resistance is low when flowing to the left, and the pump P 1 is manufactured so as to exhibit its original performance and operate normally. The speed of the water flow below the pump P suction port Pa when moving forward is almost the same as the ship speed.

However, when the jet water discharged from the outer flap 53 flows to the lower part of the hull H during the reverse travel, as shown by the one-dot chain line J in FIG. In addition to being in the opposite direction to the water flow, the jet water needs a flow velocity that can propel the hull H backward, so the jet water having a flow velocity much faster than the ship speed will flow to the lower part of the hull H. The flow velocity itself is much higher than the flow velocity of the water flow when the hull H is moving forward. Therefore, in order for the pump P to decelerate the jet water shown by the alternate long and short dash line J covering the vicinity of the suction port Pa and to reverse the direction of the flow to suck the water through the suction passage Pb, a large amount of energy is required. It takes a burden. This burden is newly generated when the vehicle is moving backward, and acts as a suction resistance of an abnormal size. Moreover, the suction resistance is not only large, but also large and small pulsations due to the waving of the jet water itself, which is indicated by the one-dot chain line J near the bottom of the ship, are also generated.

In the first place, since the pump P of the water injection propulsion device has a small suction head due to its structure, it is weak against an increase in suction resistance, and when the suction resistance increases, the pump performance deteriorates and a suction failure occurs. It may cause cavitation, which makes it difficult to continue normal driving. In addition, this increase in suction resistance may damage the pump P during reverse travel, or the jet water of the alternate long and short dash line J discharged from the pump P and discharged from the outer flap 53 may actually be weak or may be interrupted, impeding reverse travel performance. To do.

In view of the above problems, an object of the present invention is to provide a reverse thrust reduction preventing device for a water jet propulsion device in which jet water does not increase suction resistance of a pump during reverse travel.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, a reverse thrust reduction preventing device for a water injection propulsion device according to the present invention is, as a first invention, a cylindrical nozzle pipe connected to an outlet portion of a pump, and an inside of the nozzle pipe. In a water jet propulsion device having an inner flap provided and an outer flap provided in a lower portion, a flow dividing member that expands from the base portion toward the jet water outlet side end portion is formed on the inner side of the outer flap so as to project in two directions. It is characterized by the formation of separate jet water passages.

A second invention is characterized in that a concave portion is formed on the outside of the outer flap, the concave portion gradually expanding from the outer flap base portion side of the outer surface of the flow dividing member toward the jet water outlet side end portion. Is.

Further, a third invention is characterized in that a flow dividing member is formed on the surface of the inner flap facing the pump outlet side so that the vertical center of the inner flap bulges toward the pump outlet side. It is what

[0012]

[Action]

 According to the first invention, when the outer flap descends during reverse travel, the jet water is discharged to the bow side by the outer flap. At this time, the jet water expands from the inner base of the outer flap toward the jet water outlet side end. Since the jet water passage is divided into two parts by the flow dividing member formed so as to project, the jet water is divided into two in the port and port directions along the jet water passage and discharged to the outside of the ship. Therefore, the jet water does not cover the suction port when moving backward.

According to a second aspect of the present invention, the jet water is divided into two in the port and starboard directions by the first aspect and is discharged to the outside of the ship, and the water flow due to reverse travel is provided on the outer surface of the flow dividing member of the outer flap. Since it enters from the concave part, the jet water is further divided into two parts, and a slow water flow is introduced into the central part.

Further, according to the third invention, the jet water discharged from the pump is formed on the surface of the inner flap facing the pump outlet side, and the vertical center is divided into two by the flow diverting member bulging toward the pump outlet side. Flow to the outer flap, and the flow diverting member of the outer flap makes sure that the outer flap is bisected and discharged to the outside.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view showing a hull equipped with a water jet propulsion device according to the present invention, FIG. 2 (a) is a bottom view of the hull shown in FIG. 1, and FIG. 2 (b) is a view of FIG. 2 (a). It is a flow-velocity distribution map in the AA arrow part.

As shown in the figure, as a water jet propulsion device, a cylindrical nozzle tube 1 is connected to an outlet of a pump P, an inner flap 2 is inside the nozzle tube 1, and an outer side is below the nozzle tube 1. Each flap 3 is provided. On the other hand, the pump P sucks water from the suction port Pa on the bottom surface of the hull H through the suction passage Pb, and in the case of the reverse travel shown in the drawing, the nozzle pipe 1, the inner flap 2, and the outer flap 3 are discharged from the pump outlet Pc. After that, it is discharged as jet water to the lower part of the hull H, which is the lower right part of the figure, to obtain reverse thrust. Then, as shown in FIG. 2A, the outer flap 3 is provided with a reverse thrust reduction preventing mechanism, which will be described later. That is, the flow dividing member 4 is formed at the center of the outer flap 3, and the jet water passages 5 are formed on both sides of the flow dividing member 4. Further, on the outer surface of the flow dividing member 4, there is formed a concave portion 6 which is gradually inclined toward the end portion of the outer flap 3. Reference numerals 7 and 8 are levers and links for opening and closing the inner flap 2 and the outer flap 3. The range indicated by the one-dot chain line J indicates the flow of jet water.

A first embodiment of the reverse thrust reduction preventing device according to the present invention in the water jet propulsion device will be described in detail with reference to the perspective views shown in FIGS. 3 (a) and 3 (b). In the first embodiment, the outer flap 3 is formed with a diverting member 4A having a triangular cross section so as to project the jet water into the lateral direction on the inner side and discharge the effluent to the outside of the ship. By providing the member 4A at the center of the inside of the outer flap 3, a jet water passage 5A is formed inside the outer flap 3 so as to be separated in two directions. In the first embodiment, the jet water passage 5A is formed so as to expand from the inner base portion 3a toward the jet water outlet side end portion 3b, and is formed along the flow direction of the jet water as shown by the arrow. It is V-shaped.

Further, on the outer side corresponding to the outer surface of the flow dividing member 4A formed inside the outer flap 3, particularly on the jet water outlet side end portion 3b of the outer flap 3 as is apparent from FIG. 3 (b). A concave portion 6A is formed so as to gradually incline toward it. The concave portion 6A has a triangular cross-section that rises from the base portion 3a of the outer flap 3 toward the jet water outlet side end portion 3b and near the uppermost portion which is the outlet side end portion 3b of the outer flap 3. Therefore, the slow water flow can be introduced to the central part.

As a result, as shown in FIG. 2 (a), the water flow due to the backward movement of the hull H is short between the two jet waters indicated by the long arrows that are discharged in two in the port and starboard directions. As shown in, it will rise and enter. Therefore, as shown in the flow velocity distribution chart in Fig. 2 (b), the jet water with a high velocity flows on the port and starboard side, and the water with a low velocity flows in the central part. It is possible to further ensure that the jet water is split into two without matching. Further, since the water flow having a slow flow rate passes through the suction port Pa, the suction resistance of the pump P does not increase.

Next, a second embodiment will be described in detail with reference to the perspective views shown in FIGS. 4 (a) and 4 (b). In the second embodiment, the shape of the flow dividing member 4A provided on the outer flap 3 of the first embodiment is changed, and the flow dividing member 4B formed in the center of the inner side of the outer flap 3 is formed into a triangular shape having a flat upper portion. By forming the columnar shape, the flow dividing member 4B achieves more reliable left and right separation of the jet water passage 5B formed inside the outer flap 3. In the second embodiment, the jet water passage 5B is formed so as to expand from the base portion toward the jet water outlet side end portion, and Y along the flow direction of the jet water is indicated by an arrow shown in the drawing. Formed in a mold.

Also in this second embodiment, as is clear from FIG. 4 (b) in particular, on the outside corresponding to the back surface of the central flow dividing member 4B, from the base portion 3a of the outer flap 3 to the jet water outlet side end portion. A concave portion 6B is formed so as to rise near the uppermost portion which is the outlet side end portion 3b of the outer flap 3 as it approaches 3b. As a result, the backward running water of the ship H rises and enters into the jet water shown by the long arrow, which is divided into two in the port and starboard directions and is discharged from the jet water passage 5B. As in the first embodiment, the jet water is further divided into two.

In the first and second embodiments, the flow dividing member 4A or 4B, which is a flow dividing member, is shown in an extremely large size for the sake of description, but in reality, the jet water passage 5A is used. Or, in order to divide the 5B into a smoother and more reliable manner, the flow dividing member 4A or 4B in the central portion is formed to have an intermediate shape of the illustrated size or a shape with a curved surface added. Any shape may be used as long as it can divide the jet water into two. In addition, all of the above-described embodiments show examples in which the flow dividing member and the concave portion are integrally formed on the outer flap 3.

Next, the third embodiment will be described in detail with reference to the plan view taken along the line BB of FIG. 1 shown in FIG. 5 and the sectional view taken along the line CC of FIG. 5 shown in FIG. As for the inner flap 2, as shown in the figure, the inner surface of the inner flap 2 facing the outlet side of the pump P is included in a vertical plane including the central axis of the nozzle tube 1. A flow dividing member 4C having a triangular cross section with a ridge 9 bulges toward the outlet side of the pump P.

With such a configuration, as shown in particular by the arrow in FIG. 5, when the jet water discharged from the pump P comes into contact with the inner flap 2 due to the swelling of the flow dividing member 4C having a triangular cross section. In the jet water passage 5C in the outer flap 3, the loss due to the sudden change in the flow direction is reduced. .

In the third embodiment described above, the inner flap 2 is divided into two parts, the upper and lower parts. However, even if the inner flap 2 is composed of one inner flap as in FIG. One effect is obtained.

As described above, according to the present invention, the jet water having a high flow velocity discharged from the water jet propulsion device does not cover the lower portion of the suction port Pa of the pump P. It does not increase the suction resistance that occurs in the.

Further, although all the above-described embodiments have been described by taking a uniaxial ship as an example, the present invention can easily cope with even a twinaxial ship by mounting two sets on the port side, Further, the same effects as those of the above-described embodiment can be obtained, and the present invention is not particularly limited to the uniaxial ship.

[0028]

[Effect of device]

 According to the present invention, the jet water discharged from the outer flap does not directly cover the suction port of the pump when the vehicle is reversing, thus preventing the suction resistance from increasing and thereby damaging the pump and reducing the reverse performance. An excellent effect of preventing is obtained.

Further, especially when a concave portion is formed on the outer surface of the flow dividing member, a water flow having a slow flow velocity is introduced into the central portion, so that the jet water is surely divided into two, and the slow water flow is pumped. Since it is supplied to the suction port, deterioration of pump performance can be prevented.

[Brief description of drawings]

FIG. 1 is a side view showing a hull equipped with a reverse thrust reduction preventing device according to the present invention.

FIG. 2 (a) is a bottom view showing a hull equipped with a reverse thrust reduction preventing device for a water injection propulsion device according to the present invention;
[Fig. 4] is a flow velocity distribution diagram in the AA arrow part of (a).

3A and 3B are perspective views of an outer flap according to a first embodiment of the present invention, in which FIG. 3A is a perspective view seen from above and FIG. 3B is a perspective view seen from below.

4A and 4B are perspective views of an outer flap according to a second embodiment of the present invention, in which FIG. 4A is a perspective view seen from above and FIG. 4B is a perspective view seen from below.

5 is a plan view taken along the line BB of FIG. 1 according to the third embodiment of the present invention.

6 is a cross-sectional view taken along line CC of FIG. 5, according to a third embodiment of the present invention.

FIG. 7 is a side sectional view showing a conventional water jet propulsion device.

FIG. 8 is a side view showing a hull equipped with a conventional water jet propulsion device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Nozzle tube 2 ... Inner flap 3 ... Outer flap 4,4A, 4B, 4C ... Flow dividing member 5, 5A, 5B, 5C ... Jet water passage 6, 6A, 6B ... Recess 9 ... Ridge P ... Pump H ... Hull

Claims (3)

[Scope of utility model registration request] 1. A water jet propulsion apparatus having a tubular nozzle tube connected to an outlet of a pump, an inner flap provided inside the nozzle tube, and an outer flap provided at a lower portion, wherein the inner side of the outer flap is provided. A backward thrust reduction preventing device for a water injection propulsion device, characterized in that a flow dividing member that expands from a base portion toward an end portion on the jet water outlet side is formed to project to form a jet water passage that is separated in two directions. 2. On the outer side of the outer flap according to claim 1,
2. The reverse thrust reduction preventing device according to claim 1, wherein a concave portion is formed which gradually expands from the outer flap base side of the outer surface of the flow dividing member toward the jet water outlet side end. 3. The flow dividing member, wherein the vertical center of the inner flap bulges toward the pump outlet side, is formed on the surface of the inner flap facing the pump outlet side according to claim 1. The reverse thrust reduction prevention device according to claim 1 or claim 2.