Water cannon

Abstract

To provide a water cannon with a simple structure that can prevent water discharge below a predetermined pressure. [Solution] The water gun 1 according to the present invention discharges pressurized water from a nozzle 3 and includes a cover member 5 provided to cover at least the front of the water outlet 3a of the nozzle 3, preventing the pressurized water discharged from the water outlet 3a from being discharged forward by impact, and a support mechanism 7 that supports the cover member 5. The support mechanism 7 maintains a state in which the cover member 5 covers the front of the water outlet 3a until the pressurized water discharged from the water outlet 3a reaches a predetermined discharge pressure, and when the pressure of the pressurized water discharged from the water outlet 3a reaches a predetermined discharge pressure, the cover member 5 retracts from the front of the water outlet 3a due to the impact pressure of the pressurized water, releasing the state in which it covers the water outlet 3a.

Description

Technical Field

[0001] The present invention relates to a water cannon used for fire protection of cultural heritage buildings and the like.

Background Art

[0002] Conventionally, a water cannon has been used as a fire protection facility for protecting cultural heritage buildings and the like from fire (see, for example, Patent Document 1). When a fire breaks out in the vicinity, water is sprayed from the water cannon toward the roof of the cultural heritage building or the like, and the entire roof is evenly wetted to prevent the cultural heritage building or the like from catching fire from flying fire powder or radiant heat.

[0003] Further, Patent Document 2 discloses a water discharge limiting device that limits the water discharge of a water cannon or the like until the water discharge pressure reaches a predetermined pressure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the problems of a water cannon for fire protection of cultural heritage structures and the like, taking a pole-type water cannon as an example, it will be described below. FIG. 6 shows a cultural heritage structure 27 and a conventional water cannon 29 provided in the vicinity thereof. The water cannon 29 is installed by connecting the flange of the water cannon main body 33 to the flange provided at the upper end of a pole 31 erected on the ground. The nozzle 3 provided on the water cannon main body 33 is set at a water discharge angle so that water is discharged toward the roof 27a of the cultural heritage structure 27. Pole 31 also functions as a water supply pipe that supplies pressurized water W to the water cannon 29, and the water cannon 29 discharges water after receiving water from pole 31.

[0006] As shown in Figure 6, in order to spray water onto the roof 27a of the cultural heritage structure 27, it is necessary to pressurize the water using a pump or the like. However, since the pump is activated and pressurization begins when a fire is detected, it takes a certain amount of time for the water discharge pressure to reach the predetermined pressure. Therefore, immediately after the pump is started, the discharge pressure is insufficient, and the intended discharge distance cannot be achieved. As shown in Figure 7, pressurized water W is discharged towards walls 27b and other areas that are not the intended target, potentially damaging or soiling the wall surface or any valuable decorations on it.

[0007] To address the above-mentioned problems, conventionally, as shown in Figure 8, the nozzle 3 of the water cannon 29 was kept facing upwards during normal times, and only after the water pressure reached a specified value was the nozzle 3 rotated as shown by the arrow in the figure to spray water towards the roof 27a of the cultural property structure 27. In this way, while the water discharge pressure is insufficient, the pressurized water W is released upward, thus preventing the pressurized water W from being discharged towards the wall 27b of the cultural property structure 27.

[0008] However, in the water cannon 29 shown in Figure 8, the nozzle 3 rotates to a predetermined water discharge angle only after the water discharge pressure reaches a specified value. Therefore, if debris clogs the rotating part, it may not rotate to the predetermined water discharge angle, potentially resulting in an unintended water discharge.

[0009] To address these problems, using a water discharge limiting device like the one described in Patent Document 2 can prevent water discharge at pressures other than a predetermined pressure, thus allowing the nozzle 3 to always be directed towards cultural heritage structures and the like. However, the water discharge limiting device described in Patent Document 2 has a complex structure and is costly, so there was a need for a simpler method that could prevent water discharge at pressures other than the predetermined discharge pressure.

[0010] This invention was made to solve the above-mentioned problems, and aims to provide a water cannon with a simple structure that can prevent water discharge at pressures other than a predetermined pressure. [Means for solving the problem]

[0011] (1) The water gun according to the present invention discharges pressurized water from a nozzle, The nozzle has a cover member provided so as to cover at least the front of the water outlet, preventing pressurized water discharged from the water outlet from being discharged forward by impact, and a support mechanism for supporting the cover member. The support mechanism is, Until the pressurized water discharged from the discharge port reaches a predetermined discharge pressure, the cover member is supported in a state that covers the front of the discharge port. The invention is characterized in that, when the pressure of the pressurized water discharged from the discharge port reaches the predetermined discharge pressure, the cover member retracts from the front of the discharge port due to the impact pressure of the pressurized water, thereby releasing the cover from the discharge port.

[0012] (2) Furthermore, in the device described in (1) above, the support mechanism is characterized by comprising: a support member having one end fixed to the cover member and the other end rotatably attached to the nozzle to support the cover member; and a rotating mechanism configured to rotate the support member to retract the cover member when the pressurized water impacting the cover member reaches a predetermined pressure.

[0013] (3) In addition, in the case described in (2) above, the support member consists of a pair of left and right arm members, The rotating mechanism comprises: an elongated hole formed axially on the base end side of the arm member; a pivot shaft provided in the side wall of the nozzle and inserted through the elongated hole; a spring with one end attached to the arm member and the other end attached to the nozzle, biasing the arm member towards the other end; a pressure plate provided continuously at the lower part of the cover member, which converts the impact force of the pressurized water into a rotational force that causes the arm member to rotate downward together with the cover member; and a holding member extending from the cover member or the pressure plate toward the nozzle, contacting the nozzle, and holding the arm member so as not to rotate. When the water discharge pressure reaches a predetermined pressure, the pressure of the pressurized water impacting the cover member causes the arm member to move in the water discharge direction against the biasing force of the spring, causing the holding member to move away from the nozzle. At the same time, the pressure of the pressurized water impacting the pressure receiving plate causes the arm member to rotate around the pivot axis, causing the cover member to retract.

[0014] (4) In addition, in the case described in (3) above, the holding member consists of a plate-shaped member extending from the pressure receiving plate, The holding member is characterized by working in cooperation with the pressure-receiving plate to convert the impact force into rotational force.

[0015] (5) In addition, in the case described in (1) above, the support mechanism is The cover member has a support piece that extends from its outer circumference toward the nozzle, is attached to the side wall of the nozzle to resist movement in the water discharge direction, and supports the cover member. The invention is characterized in that when the impact force of the pressurized water striking the cover member becomes greater than the resistance force of the support piece, the support piece moves in the direction of water discharge and detaches from the nozzle. [Effects of the Invention]

[0016] The present invention includes a cover member that covers the front of a water discharge port and a support mechanism that supports the cover member. The support mechanism is configured such that when a predetermined water discharge pressure is reached, the cover member retreats from the front of the water discharge port due to the impact pressure of the pressurized water, and the state of covering the water discharge port is released. Therefore, with a simpler structure than conventional ones, it is possible to prevent water discharge below a predetermined water discharge pressure. Also, the nozzle can be directed toward a cultural property structure or the like even during normal times, and since the nozzle angle is not changed during water discharge, the nozzle angle does not change due to a malfunction.

Brief Description of the Drawings

[0017] [Figure 1] It is an explanatory diagram of a water gun according to Embodiment 1 of the present invention. [Figure 2] It is a diagram for explaining the operation of the water gun in FIG. 1 (Part 1). [Figure 3] It is a diagram for explaining the operation of the water gun in FIG. 1 (Part 2). [Figure 4] It is an explanatory diagram of a water gun according to Embodiment 2 of the present invention. [Figure 5] It is a diagram for explaining the operation of the water gun in FIG. 4 [Figure 6] It is a diagram for explaining the problems of a conventional water gun (Part 1). [Figure 7] It is a diagram for explaining the problems of a conventional water gun (Part 2). [Figure 8] It is a diagram for explaining the problems of a conventional water gun (Part 3).

Modes for Carrying Out the Invention

[0018] [Embodiment 1] The water gun 1 according to Embodiment 1 of the present invention will be described based on FIG. 1. FIG. 1 is a side view of the nozzle 3 of the water gun 1, and the left side in the figure is the front of the water gun 1, that is, the side where a cultural property structure or the like is installed. The nozzle 3 receives water supply through the water gun body 19 (see FIG. 6) and discharges pressurized water from the water discharge port 3a provided at the tip of the nozzle 3.

[0019] As shown in Figure 1, the water cannon 1 of this embodiment has a cover member 5 that covers the front of the water outlet 3a and a support mechanism 7 that supports the cover member 5. The cover member 5 and support mechanism 7, which are features of this embodiment, will be described in detail below.

[0020] <Cover component> The cover member 5 is a component that prevents pressurized water discharged from the water outlet 3a from being discharged in front of the water cannon 1 by colliding with it. The cover member 5 is positioned opposite the water outlet 3a with a predetermined gap in between, so as to cover at least the front of the water outlet 3a. The upper part of the cover member 5 is bent towards the rear of the water outlet 3a, so that some of the pressurized water that hits the cover member 5 is scattered behind the water outlet 3a.

[0021] <Support mechanism> The support mechanism 7 includes an arm member 9 and a rotating mechanism 11 configured to rotate the arm member 9 to move the cover member 5 away from the front of the water outlet 3a when the pressurized water impacting the cover member 5 reaches a predetermined pressure.

[0022] Arm component The arm members 9 are support members that support the cover member 5, and a pair of them are provided on the left and right sides of the cover member 5. Here, left and right refers to the left and right when viewing the surface of the cover member 5 from the front, which in Figure 1 is the back and front of the paper. In Figure 1, only the arm member 9 on the front side of the pair of arm members 9 is shown. Each of the pair of arm members 9 has one end fixed to the cover member 5 and the other end rotatably attached to the nozzle 3.

[0023] Rotating mechanism The rotating mechanism 11 includes an elongated hole 9a formed in the arm member 9, a pivot shaft 13 provided on the side wall of the nozzle 3, a spring 15 that biases the arm member 9 to pull it in the opposite direction to the water discharge direction, a pressure receiving plate 17 provided continuously at the lower part of the cover member 5, and a holding member 19 provided so as to extend from the tip of the pressure receiving plate 17 toward the nozzle 3.

[0024] The elongated hole 9a is formed on the base end side of the arm member 9 so as to extend in the axial direction. The pivot shafts 13 are projected from the left and right side walls of the nozzle 3 (the front and back of the page in Figure 1) and are inserted through the elongated holes 9a of the pair of arm members 9.

[0025] The spring 15 has one end attached to the arm member 9 and the other end attached to the side wall of the nozzle 3, and is biased to pull the arm member 9 toward the other end. Furthermore, the biasing force of the spring 15 and the area of ​​the cover member 5 are adjusted so that when the pressure of the pressurized water discharged from the discharge port 3a, i.e., the impact pressure on the cover member 5, exceeds a predetermined pressure, the spring 15 extends to a position where the retaining member 19, described later, detaches from the lower surface of the nozzle 3. Under normal conditions, the arm member 9 is pulled in by the spring 15 until the pivot shaft 13 contacts the longitudinal end of the elongated hole 9a (see Figure 1). In this state, the cover member 5 is positioned opposite the water outlet 3a with a predetermined gap between them.

[0026] The pressure plate 17 is a plate-shaped member that converts the impact force of the pressurized water into a rotational force that causes the arm member 9 to rotate downward together with the cover member 5, and is provided so as to extend from the lower end of the cover member 5 toward the nozzle 3. Here, "rotating downward" refers to the rotation of the arm member 9 so that the cover member 5 moves to the lower side of the pivot axis 13.

[0027] The holding member 19 is a plate-shaped member that extends from the pressure receiving plate 17 toward the nozzle 3, and is positioned to contact the lower surface of the nozzle 3 when the spring 15 pulls the arm member 9 towards it. The holding member 19 contacts the lower surface of the nozzle 3, preventing the arm member 9 from rotating, thereby maintaining the state in which the cover member 5 covers the water outlet 3a.

[0028] In this embodiment, the holding member 19 is a plate-shaped member, but it is not limited to this as long as it can contact the lower surface of the nozzle 3 and suppress the rotation of the arm member, for example, it may be a rod-shaped member. However, it is more preferable that the holding member 19 is plate-shaped, as it can cooperate with the pressure receiving plate 17 to convert the impact force of the pressurized water into rotational force of the arm member.

[0029] Furthermore, the pressure plate 17 and the holding member 19 are arranged to form a V-shape with the upper side open. In this way, the pressurized water that collides with the pressure plate 17 and the holding member 19 concentrates at the bend of the V-shape, making it easier for the impact force of the pressurized water to be converted into rotational force of the arm member 9.

[0030] The above is an example in which the retaining member 19 is provided so as to extend from the tip of the pressure receiving plate 17, but the present invention is not limited to this, and the retaining member 19 may also be provided so as to extend from the lower part of the cover member 5 toward the nozzle 3. Even in this configuration, the tip of the holding member 19 contacts the lower surface of the nozzle 3, thereby holding the arm member 9 in place and preventing it from rotating. Furthermore, by making the holding member 19 plate-shaped, it can work in cooperation with the pressure receiving plate 17 to convert the impact pressure of the pressurized water into rotational force for the arm member.

[0031] Next, the operation of the water cannon 1 of this embodiment, configured as described above, will be explained. A fire breaks out near a cultural heritage structure, a pump (not shown) is activated, and pressurized water is supplied to water cannon 1, which is then discharged from nozzle 3a. The pressurized water released from the discharge port 3a collides with the cover member 5 and flows out from between the cover member 5 and the nozzle 3, and is discharged to the sides and rear of the water cannon 1.

[0032] The cover member 5 is pressed by the pressurized water discharged from the discharge port 3a, but immediately after the pump is started, the discharge pressure is low and is below the biasing force of the spring 15, so the discharge port 3a remains covered by the cover member 5. Therefore, pressurized water is not discharged in front of the water cannon 1 until the pressurized water reaches a predetermined discharge pressure.

[0033] When the water discharge pressure reaches a predetermined pressure, as shown in Figure 2, the impact pressure of the pressurized water hitting the cover member 5 causes the arm member 9 to move in the direction of water discharge against the biasing force of the spring 15, and the holding member 19 separates from the lower surface of the nozzle 3. When the retaining member 19 separates from the nozzle 3, the pressure of the pressurized water (see the small arrow in the figure) that strikes the pressure plate 17 and the retaining member 19 causes the arm member 9 to rotate downward (in the direction of the large arrow in the figure) around the pivot axis 13.

[0034] As a result, as shown in Figure 3, the cover member 5 retracts from in front of the water outlet 3a, releasing it from covering the water outlet 3a, and pressurized water W is discharged in front of the water gun 1 at a discharge pressure of a specified value or higher. Then, as shown in Figure 6, a predetermined amount of pressurized water W reaches the roof 27a of the cultural property structure 27, wetting the roof 27a and protecting it from sparks and other debris flying in from nearby fires.

[0035] As described above, in this embodiment, the cover member 5 covers the front of the water outlet 3a until the pressurized water reaches a predetermined pressure, so the pressurized water is discharged to the sides and rear of the water cannon 1. Therefore, since forward water discharge is suppressed when the water discharge pressure is insufficient, water will not be discharged towards the wall 27b of the cultural property structure 27, thereby preventing damage to the wall surface and any decorations applied to it.

[0036] Furthermore, since the cover member 5 is retracted from the front of the water outlet 3a by utilizing the impact pressure of the pressurized water discharged from the nozzle 3, manual or electric operation is not required. Therefore, this type of water cannon is particularly suitable when the water cannon is installed at a high location, making manual operation or the installation of electrical equipment difficult, as is the case with the pole-type water cannon shown in Figure 6. Furthermore, because it can be constructed with a simpler structure than conventional examples, it is low-cost and easy to replace when parts deteriorate.

[0037] [Embodiment 2] In this embodiment, an example of a support mechanism configured in an even simpler way than in Embodiment 1 will be explained using Figures 4 and 5. The difference from Embodiment 1 is that the support mechanism 7 has been replaced with a support mechanism 23. Other components similar to those in Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted. In order to make the shape of the support piece 25, which will be described later, easier to understand, only the cross-sectional shapes of the cover member 5 and the support mechanism 23 are shown in the diagram.

[0038] <Support mechanism> The support mechanism 23 supports the cover member 5 so that it covers the front of the water outlet 3a, and consists of a pair of support pieces 25 that extend from the outer circumference of the cover member 5 toward the nozzle 3, as shown in Figure 4.

[0039] 《Support piece》 The support piece 25 is attached to the side wall of the nozzle 3 to support the cover member 5, and two support pieces are provided on the outer circumference of the cover member 5, facing each other. The cover member 5 in Figure 4 is circular in shape, substantially the same as the water outlet 3a, and the support piece 25 provided on its outer circumference is curved to conform to the outer surface of the nozzle 4. The tip of the support piece 25 is provided with a protrusion 25a that is formed to protrude toward the nozzle 3. The number of support pieces 25 is not limited to two; three or more may be provided at equal intervals in the circumferential direction of the cover member 5. Furthermore, the support pieces 25 may extend around the entire circumference of the cover member 5, so that the cover member 5 is configured in a cap-like shape. The shapes of the cover member 5 and the support piece 25 are not particularly limited. For example, the cover member 5 may have a polygonal shape such as a rectangle when viewed from the front, and flat support pieces 25 may be provided on opposing sides of the cover member 5.

[0040] The nozzle 3 has a shape that widens towards the tip, and by attaching a pair of support pieces 25 having a protrusion 25a to the nozzle 3 of this shape, the support pieces 25 are made to resist movement in the direction of water discharge.

[0041] Since the distance between the pair of protrusions 25 is smaller than the diameter of the tip of the nozzle 3, when the cover member 5 is pressed by pressurized water and the support piece 25 moves in the direction of water discharge, the support piece 25 elastically deforms so that the distance between the protrusions 25a increases. In other words, when the support piece 25 moves in the direction of water discharge, it undergoes elastic deformation, which acts as a resistance force against movement in the direction of water discharge.

[0042] The resistance of the support piece 25 is adjusted so that the support piece 25 detaches from the nozzle 3 when the discharge pressure of the pressurized water reaches a predetermined pressure, that is, when the impact pressure of the pressurized water hitting the cover member 5 reaches a predetermined pressure. The resistance of the support piece 25 increases as the support piece 25 becomes less elastically deformable. Therefore, it is advisable to set the shape and material of the support piece 25 so that it detaches from the nozzle 3 when a predetermined water discharge pressure is reached. Furthermore, if the height of the protrusion 25a is too small, the amount of elastic deformation associated with movement will decrease, and the resistance force of the support piece 25 will also decrease. Therefore, it is desirable to set the height of the protrusion 25a appropriately.

[0043] The above is just one example of how to attach the support piece 25 to the nozzle 3 so as to resist movement in the direction of water discharge, and the present invention is not limited thereto. For example, a groove may be formed on the outer surface of the nozzle 3 to lock the protrusion 25a, and this locking force may be used as resistance to movement in the water discharge direction. In this case, the nozzle 3 does not need to have a shape that widens towards the tip. In particular, when the cover member 5 is rectangular and the support piece 25 is flat, the contact area between the outer surface of the nozzle 3 and the protrusion 25a becomes small, so it is desirable to provide the groove in a straight line along the edge of the protrusion 25a.

[0044] Alternatively, the support piece 25 may be formed using a material with a high coefficient of friction, and this frictional force may be used as resistance to movement in the water discharge direction.

[0045] In either case, if the impact force of the pressurized water hitting the cover member 5 becomes greater than the resistance force of the support piece 25, the support piece 25 moves in the direction of water discharge and detaches from the nozzle 3. Therefore, by appropriately setting the resistance force of the support piece 25, when the pressure of the pressurized water discharged from the discharge port 3a reaches a predetermined discharge pressure, the cover member 5 retracts from the front of the discharge port 3a, and the state of covering the discharge port 3a is released.

[0046] If the support piece 25 detaches from the nozzle 3, it will fall to the vicinity of the water cannon 21 along with the cover member 5. Therefore, to prevent loss, it is advisable to tie the cover member 5 or the support piece 25 to the nozzle 3 with a string or the like.

[0047] Next, the operation of the water cannon 21 of this embodiment, configured as described above, will be explained. A fire breaks out near a cultural heritage structure, a pump (not shown) is activated, and pressurized water is supplied to the water cannon 21, and the pressurized water is discharged from the nozzle 3a. Since the front of the water outlet 3a is covered by the cover member 5, the pressurized water discharged from the water outlet 3a flows out between the cover member 5 and the nozzle 3 and is discharged to the side of the water gun 21.

[0048] When water discharge begins, pressurized water collides with the cover member 5 and presses against it. However, immediately after the pump starts up, the water discharge pressure is low, and the support piece 25 resists this pressure, so the support piece 25 remains attached to the nozzle 3. Therefore, until the pressurized water reaches a predetermined discharge pressure, the cover member 5 remains covering the discharge port 3a, and pressurized water is not discharged in front of the water cannon 21.

[0049] When the water discharge pressure reaches a predetermined pressure, the support piece 25 moves in the direction of water discharge while elastically deforming due to the impact pressure of the pressurized water hitting the cover member 5. Then, as shown in Figure 5, the support piece 25 detaches from the nozzle 3 and falls around the water gun 21. As a result, the cover member 5 is released from covering the water outlet 3a, and pressurized water is discharged forward from the water cannon 21 at a discharge pressure exceeding the specified value. Then, as shown in Figure 6, a predetermined amount of pressurized water W reaches the roof 27a of the cultural property structure 27, wetting the roof 27a and protecting it from sparks and other debris flying in from nearby fires.

[0050] As described above, in this embodiment, the cover member 5 covers the front of the discharge port 3a until the pressurized water discharged from the discharge port 3a reaches a predetermined pressure, so the pressurized water discharged from the discharge port 3a is discharged to the side of the water gun 21. Therefore, similar to Embodiment 1, forward water discharge is suppressed when the water discharge pressure is insufficient, so water is not discharged towards the wall 27b of the cultural property structure 27, and damage to the wall surface and decorations applied to the wall surface can be prevented. Furthermore, the support mechanism 23 of this embodiment has a simple structure and can be easily attached to the nozzle of an existing water cannon, thus resulting in low cost.

[0051] It should be noted that the present invention is not limited to the embodiments of Embodiments 1 and 2. Other embodiments are also included in the present invention, as long as the support mechanism is configured such that the cover member covers the front of the discharge port until the discharge pressure reaches a predetermined pressure, and after the predetermined pressure is reached, the cover member retracts from the front of the discharge port due to the impact pressure of the pressurized water. [Explanation of Symbols]

[0052] 1. Water cannon (Embodiment 1) 3 nozzles 3a Water outlet 5 Cover component 7. Support mechanism (Embodiment 1) 9 Arm members 9a long hole 11. Rotating mechanism 13 rotational axes 15 springs 17 Pressure plate 19 Retaining member 21. Water cannon (Embodiment 2) 23 Support mechanism (Embodiment 2) 25 Support piece 25a Convex part 27 Cultural property structures 27a Roof 27b wall 29. Water cannon (conventional example) 31 Paul 33. Water cannon body W Pressurized water

Claims

1. A water cannon that discharges pressurized water from a nozzle, The nozzle has a cover member provided so as to cover at least the front of the water outlet, preventing pressurized water discharged from the water outlet from being discharged forward by impact, and a support mechanism for supporting the cover member. The support mechanism is, Until the pressurized water discharged from the discharge port reaches a predetermined discharge pressure, the cover member is supported in a state that covers the front of the discharge port. A water cannon is characterized in that, when the pressure of the pressurized water discharged from the water outlet reaches the predetermined discharge pressure, the cover member retracts from the front of the water outlet due to the impact pressure of the pressurized water, thereby releasing the state of covering the water outlet.

2. The water gun according to claim 1, characterized in that the support mechanism comprises a support member having one end fixed to the cover member and the other end rotatably attached to the nozzle to support the cover member, and a rotating mechanism configured to rotate the support member to retract the cover member when the pressurized water impacting the cover member reaches a predetermined pressure.

3. The support member consists of a pair of left and right arm members. The rotating mechanism comprises: an elongated hole formed axially on the base end side of the arm member; a pivot shaft provided in the side wall of the nozzle and inserted through the elongated hole; a spring with one end attached to the arm member and the other end attached to the nozzle, biasing the arm member towards the other end; a pressure plate provided continuously at the lower part of the cover member, which converts the impact force of the pressurized water into a rotational force that causes the arm member to rotate downward together with the cover member; and a holding member extending from the cover member or the pressure plate toward the nozzle, contacting the nozzle, and holding the arm member so as not to rotate. The water gun according to claim 2, characterized in that when the water discharge pressure reaches a predetermined pressure, the pressure of the pressurized water impacting the cover member causes the arm member to move in the water discharge direction against the biasing force of the spring, causing the holding member to move away from the nozzle, and the pressure of the pressurized water impacting the pressure receiving plate causes the arm member to rotate around the pivot axis, causing the cover member to retract.

4. The holding member consists of a plate-shaped member extending from the pressure receiving plate, The water cannon according to claim 3, characterized in that the holding member cooperates with the pressure receiving plate to convert the impact force into rotational force.

5. The aforementioned support mechanism is The cover member has a support piece that extends from its outer circumference toward the nozzle, is attached to the side wall of the nozzle to resist movement in the water discharge direction, and supports the cover member. The water gun according to claim 1, characterized in that when the impact force of the pressurized water striking the cover member becomes greater than the resistance force of the support piece, the support piece moves in the water discharge direction and detaches from the nozzle.

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