An emergency rescue system for elevator car failure

Abstract

The present invention discloses an emergency rescue system for a car elevator failure, comprising: a water tank, a trigger rod, a valve, and a channel; the channel is vertically mounted on the inner wall of the elevator shaft, the water tank is mounted on the elevator car, the valve is mounted at the bottom end of the water tank, one end of the trigger rod is rotatably connected to the water tank and is transmission-connected to an operating portion of the valve, and the other end of the trigger rod extends into the channel. When the elevator fails and the elevator car and the counterweight device are in weight balance, an operating ball is operated to fall along the channel and hit the trigger rod, opening the valve, and liquid in the water tank is spilled into the elevator shaft, releasing the weight balance between the elevator car and the counterweight device. The brake is released to allow the car to slide, and the elevator car rises naturally. When the elevator car is aligned with the floor, the brake is closed to initiate a rescue operation. After the elevator is repaired, the trigger rod is restored to its position, closing the valve, and the water tank is refilled to resume normal use of the emergency rescue system.

Description

Technical Field

[0001] The present invention relates to the field of elevators, and in particular to an emergency rescue system for a car elevator failure. Background Art

[0002] When the elevator loses power and cannot be automatically rescued, if the elevator car and the counterweight device are in a weight balance state, the rescue purpose cannot be achieved by releasing the brake and allowing the car to slide.

[0003] For elevators with machine rooms, rescue workers can use manual turning to perform emergency rescue.

[0004] For machine room-less elevators, rescue workers need to enter the shaft and add counterweights to the car or enter the pit to pull the compensation chain to break the weight balance between the car and the counterweight device, so that the car can be moved again and the rescue purpose can be achieved.

[0005] The above rescue measures all require professionals to undergo long-term training before they can be operated, and at least two people are required to operate them. The personnel training cycle is long and the cost is high.

[0006] Chinese patent publication number CN112125087B discloses a balance-breaking rescue device, which pre-hangs a heavy object at the bottom of the elevator car and releases the heavy object when necessary to break the balance between the elevator car and the counterweight device, so as to achieve the rescue purpose by releasing the brake and allowing the car to slide.

[0007] However, the swing of the suspended weight when the elevator car is rising or falling will increase the shaking of the elevator car, affecting the passenger experience, and how to recover the released weight is also a problem. Summary of the Invention

[0008] The purpose of the present invention is to provide an emergency rescue system for a car elevator failure to solve the technical problem that a rescue device that destroys the balance between the elevator car and the counterweight device affects the normal operation of the elevator when not in use and is difficult to restore after use.

[0009] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0010] An emergency rescue system for a car elevator failure comprises: a water tank, a trigger rod, a valve, and a channel; the channel is vertically mounted on the inner wall of the elevator shaft, allowing a rolling ball to fall in the direction of gravity, and an entrance to the channel penetrates the wall of the elevator shaft and extends to the outer wall of the elevator shaft; the water tank is mounted on the elevator car, and liquid is pre-stored in the water tank to form a counterweight; the valve is mounted at the bottom end of the water tank and connects the inner and outer sides of the water tank; one end of the trigger rod is rotatably connected to the water tank, and the other end of the trigger rod extends toward the inner wall of the elevator shaft and into the channel, the trigger rod being able to move vertically without obstruction in the channel, and the operating portion of the valve is transmission-connected to the trigger rod; when the elevator fails and the elevator car and the counterweight are in weight balance, the rolling ball is operated to enter the channel along the entrance of the channel, then fall and hit the trigger rod, which rotates to open the valve, causing the liquid in the water tank to be sprayed into the elevator shaft, the counterweight disappears, and the weight balance between the elevator car and the counterweight is broken.

[0011] Furthermore, the passage includes: a plurality of pipes connected end to end along the direction of gravity; each of the pipes corresponds to one floor of the building, and the bottom end of each pipe is connected to the top end of the pipe on the next floor of the building; an inlet and outlet hole is provided on each floor of the building, which passes through the wall of the elevator shaft and is connected to the end of the pipe, and the bottom edge of the inlet and outlet hole is connected to an inclined plate extending toward the inside of the pipe, and the pipe and the inclined plate are both provided with an avoidance opening for avoiding the vertical movement of the trigger rod in the passage, and the avoidance opening has a size that the ball cannot pass through; the inclined plate is inclined upward, and a gap is left between the side of the inclined plate away from the inlet and outlet hole and the inner wall of the pipe for the ball to pass through; the bottom end of the pipe on the upper floor of the building is located directly above the inclined plate, and the bottom end of the pipe is directly opposite the middle of the inclined plate.

[0012] Furthermore, the cross-sectional areas of the middle and bottom ends of the pipe are the same, the projected area of ​​the inclined plate on the cross-sectional area of ​​the pipe is equal to the cross-sectional area of ​​the bottom end of the pipe, and a radially outwardly expanding socket is formed at the top end of the pipe, and the cross-sectional area of ​​the socket is equal to twice the cross-sectional area of ​​the bottom end of the pipe.

[0013] Furthermore, the bottom end of each of the pipes is inserted into the socket of the pipe located on the next floor of the building, and the top end of the socket is higher than the top end of the inclined plate.

[0014] Furthermore, the bottom edge of the access hole is flush with the ground of each floor of the building.

[0015] Furthermore, a reset block is provided at the bottom of the elevator shaft. When the elevator car moves to the bottom of the elevator shaft, the bottom of the trigger rod contacts the top of the reset block to restore the initial posture.

[0016] Furthermore, a water outlet is provided on the side wall of the water tank; the valve includes a rotating part, which is rotatably connected to the water tank around a horizontal axis, the proximal end of the trigger rod is fixedly connected to the rotating part and is an integral part, the trigger rod is a hollow tube, and a water through hole connected to the distal end of the trigger rod is formed on the side of the rotating part that is in contact with the water tank; when the trigger rod is in an initial posture, the rotating part closes the water outlet, and after the trigger rod collides with the rolling ball, the rotating part rotates so that the water outlet and the water through hole coincide, and the liquid in the water tank is thrown into the interior of the elevator shaft through the water outlet, the water through hole and the trigger rod.

[0017] Furthermore, a water supply hole is provided above the water outlet hole, and when the trigger rod is in an initial posture, the water supply hole and the water flow hole overlap.

[0018] Furthermore, the outer wall of the water tank is provided with two stoppers located on the upper and lower sides of the rotating member, and the stoppers are used to limit the rotation angle of the rotating member.

[0019] Furthermore, a one-way valve is installed on the water supply hole, and the one-way valve is used to prevent the water inside the water tank from flowing out through the water supply hole; or a water supply pipe is installed inside the water tank, one end of the water supply pipe is connected to the water supply hole, and the other end of the water supply pipe is close to the top wall of the water tank.

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] This system provides an emergency rescue system for elevator car failures. When an elevator fails and the elevator car and counterweight are in weight balance, a ball is operated to enter the passage along the entrance, then fall and strike a trigger lever. The trigger lever rotates to open the valve, causing the liquid inside the water tank to spill into the elevator shaft. The counterweight disappears, and the weight balance between the elevator car and the counterweight is released. The brake is then released to allow the car to coast, allowing it to naturally rise. When the elevator car is aligned with the floor, the brake is closed, and rescue operations can begin. After the elevator is repaired, the trigger lever is restored to its original position, closing the valve, and the water tank is refilled to resume normal operation of the emergency rescue system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0023] Figure 1 A simplified structural diagram of an embodiment of the present invention;

[0024] Figure 2 A simplified structural diagram of a channel according to an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a process in which a rolling ball hits a trigger rod in a channel to cause the trigger rod to rotate according to an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of a process of returning to an initial posture when the trigger lever contacts a reset block according to an embodiment of the present invention;

[0027] Figure 5 A structural perspective view of a corner of an elevator shaft according to an embodiment of the present invention;

[0028] Figure 6 A structural side view of a corner of an elevator shaft according to an embodiment of the present invention;

[0029] Figure 7 for Figure 6 Cross-sectional view in the AA direction;

[0030] Figure 8 This is a structural perspective diagram of a passage located in a corner of an elevator shaft according to an embodiment of the present invention;

[0031] Figure 9 A structural perspective view of a water tank, a trigger rod, and a valve according to an embodiment of the present invention;

[0032] Figure 10 A three-dimensional diagram of a trigger lever according to an embodiment of the present invention;

[0033] Figure 11 A structural perspective view of a corner of a water tank according to an embodiment of the present invention;

[0034] The numbers in the figure represent the following:

[0035] 1- Elevator shaft; 11- Elevator car; 12- Counterweight device; 2- Water tank; 21- Water outlet; 22- Water supply hole; 23- Stopper; 24- Water supply pipe; 3- Trigger rod; 4- Valve; 41- Rotating part; 42- Water flow hole; 5- Rolling ball; 6- Channel; 61- Inlet and outlet hole; 62- Pipeline; 63- Socket; 64- Inclined plate; 65- Avoidance opening; 7- Reset block. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] An emergency rescue system for elevator failure, please refer to Figure 1 .

[0038] The emergency rescue system includes: a water tank 2, a trigger rod 3, a valve 4 and a channel 6;

[0039] The channel 6 is installed vertically on the inner wall of the elevator shaft 1. The channel 6 allows the ball 5 to fall along the direction of gravity. The entrance of the channel 6 passes through the wall of the elevator shaft 1 and extends to the outer wall of the elevator shaft 1.

[0040] A water tank 2 is mounted on the elevator car 11. Liquid is pre-stored in the water tank 2 to form a counterweight. A valve 4 is mounted at the bottom of the water tank 2 and connects the inner and outer sides of the water tank 2.

[0041] One end of the trigger rod 3 is rotatably connected to the water tank 2, and the other end of the trigger rod 3 extends toward the inner wall of the elevator shaft 1 and extends into the channel 6. The trigger rod 3 can move vertically in the channel 6 without obstruction. The operating part of the valve 4 is transmission-connected to the trigger rod 3.

[0042] When the elevator breaks down and the elevator car 11 and the counterweight device 12 are in weight balance, the ball 5 is operated to enter the interior of the channel 6 along the entrance of the channel 6, then fall and hit the trigger rod 3. The trigger rod 3 rotates to open the valve 4, and the liquid inside the water tank 2 is thrown into the elevator shaft 1. The counterweight disappears and the weight balance between the elevator car 11 and the counterweight device 12 is released.

[0043] After the weight balance between the elevator car 11 and the counterweight device 12 is released, the brake is released to slide the car, and the elevator car 11 rises naturally. When the elevator car 11 is aligned with the level floor, the brake is closed to start the rescue operation.

[0044] After the elevator is repaired, the position of the trigger rod 3 is restored to close the valve 4, and then the water tank 2 is refilled to restore the normal use of the emergency rescue system.

[0045] Further:

[0046] When the elevator shaft 1 has a high number of floors and the height of the faulty elevator car 11 is high, the rolling ball 5 continues to accelerate while falling along the channel 6, and hitting the trigger rod 3 is likely to cause damage to the trigger rod 3, and falling to the bottom of the elevator shaft 1 is likely to cause the ground to crack.

[0047] In order to solve this technical problem, Figure 2 As shown:

[0048] The channel 6 includes: a plurality of pipes 62 connected end to end along the direction of gravity;

[0049] Each pipe 62 corresponds to one floor of the building, and the bottom end of each pipe 62 is connected to the top end of the pipe 62 located on the next floor of the building;

[0050] An inlet and outlet hole 61 is provided on each floor of the building, penetrating the wall of the elevator shaft 1 and connected to the end of a pipe 62. The bottom edge of the inlet and outlet hole 61 is connected to an inclined plate 64 extending toward the interior of the pipe 62. Both the pipe 62 and the inclined plate 64 are provided with an avoidance opening 65 for avoiding vertical movement of the trigger rod 3 in the channel 6.

[0051] The inclined plate 64 is inclined upward, and a gap is left between the side of the inclined plate 64 away from the inlet and outlet hole 61 and the inner wall of the pipe 62 for the ball 5 to pass through;

[0052] The bottom end of the pipe 62 located on the upper floor of the building is located directly above the inclined plate 64 , and the bottom end of the pipe 62 faces the middle of the inclined plate 64 .

[0053] In order to ensure that the ball 5 will inevitably fall onto the inclined plate 64 after passing through the bottom end of the pipe 62, the cross-sectional area of ​​the pipe 62 gradually decreases from its top end toward its bottom end.

[0054] Please refer to the working principle of the above structure Figure 3 Assuming that the bottom end of the elevator is between the 18th and 19th floors, the staff moves to the 19th floor and places the ball 5 into the inlet and outlet hole 61 on the 19th floor. The ball 5 moves along the inlet and outlet hole 61 and the inclined plate 64 to between the inclined plate 64 and the inner wall of the pipe 62, then enters the top of the pipe 62 and falls along the pipe 62. The ball 5 falls through the bottom end of the pipe 62 onto the inclined plate 64 on the 18th floor, and then leaves the passage 6 along the inlet and outlet hole 61 on the 18th floor.

[0055] In this way, no matter which floor the elevator breaks down, the maximum falling distance of the ball 5 will not exceed the height of one floor, and its falling speed is limited, which is unlikely to cause damage to the trigger rod 3 and the ground.

[0056] Further:

[0057] In order to reduce the material used in the pipe 62, as Figure 3 As shown:

[0058] The cross-sectional areas of the middle and bottom ends of the pipe 62 are the same, the projected area of ​​the inclined plate 64 on the cross-sectional area of ​​the pipe 62 is equal to the cross-sectional area of ​​the bottom end of the pipe 62, and a radially outwardly expanding socket 63 is formed at the top end of the pipe 62, and the cross-sectional area of ​​the socket 63 is equal to twice the cross-sectional area of ​​the bottom end of the pipe 62.

[0059] Compared to Figure 2 The structure of the pipe 62 shown, Figure 3 The illustrated conduit 62 uses less material and is less expensive.

[0060] Further:

[0061] The bottom end of each pipe 62 is inserted into the socket 63 of the pipe 62 located on the next floor of the building, and the top end of the socket 63 is higher than the top end of the inclined plate 64.

[0062] This design is used to prevent the ball 5 from flying over the top of the socket 63 and then falling into the elevator shaft 1 after passing through the inclined plate 64 when the ball 5 enters the interior of the inlet and outlet hole 61 with a high initial velocity.

[0063] Further:

[0064] The bottom edge of the access hole 61 is flush with the ground of each floor of the building.

[0065] The height of the entry and exit hole 61 makes it easy for the staff to push the ball 5 from the ground, so that the ball 5 enters the entry and exit hole 61 along the ground of the current floor at a certain initial velocity, thereby passing over the inclined plate 64 and entering the interior of the socket 63.

[0066] At the same time, there is no height difference between the rolling ball 5 leaving the passage 6 through the inlet and outlet hole 61 on the next floor of the building and the ground of the current floor, so the ground will not be damaged.

[0067] Furthermore, if Figure 4 As shown:

[0068] A reset block 7 is provided at the bottom of the elevator shaft 1. When the elevator car 11 moves to the bottom of the elevator shaft 1, the bottom of the trigger rod 3 contacts the top of the reset block 7 to restore the initial posture.

[0069] The initial posture of the trigger rod 3 is a horizontal posture.

[0070] Further, please refer to Figure 5-11 ,in Figure 5-8 A corner of the elevator shaft 1 is shown. There are two pipes 62 in the figure, and the connection part of the two pipes 62 is taken as a schematic diagram. The water tank 2 in the figure also only shows a corner thereof as a schematic diagram.

[0071] The side wall of the water tank 2 is provided with a water outlet 21;

[0072] The valve 4 includes a rotating member 41, which is rotatably connected to the water tank 2 about a horizontal axis. The proximal end of the trigger rod 3 is fixedly connected to the rotating member 41 and is an integral part. The trigger rod 3 is a hollow tube. The surface of the rotating member 41 that contacts the water tank 2 is formed with a water hole 42 that communicates with the distal end of the trigger rod 3.

[0073] When the trigger rod 3 is in the initial position, the rotating part 41 closes the water outlet 21. After the trigger rod 3 collides with the ball 5, the rotating part 41 rotates so that the water outlet 21 and the water through hole 42 coincide with each other, and the liquid in the water tank 2 is thrown into the interior of the elevator shaft 1 through the water outlet 21, the water through hole 42 and the trigger rod 3.

[0074] The liquid flowing out through the far end of the trigger rod 3 is mainly located inside the pipe 62, and the bottom end of the pipe 62 is directly connected to the drainage ditch at the bottom of the elevator shaft 1, thereby preventing water from accumulating at the bottom of the elevator shaft 1 and preventing the inner wall surface of the elevator shaft 1 from getting wet.

[0075] Furthermore, if Figure 9 As shown:

[0076] A water replenishing hole 22 is provided above the water outlet hole 21 . When the trigger lever 3 is in the initial posture, the water replenishing hole 22 and the water passing hole 42 overlap.

[0077] When the water supply hole 22 and the water flow hole 42 overlap, the trigger rod 3 can be connected to the water pipe to supply water to the inside of the water tank 2 through the water pipe.

[0078] Furthermore, if Figure 11 As shown:

[0079] The outer wall of the water tank 2 is provided with two stoppers 23 located at the upper and lower sides of the rotating member 41 . The stoppers 23 are used to limit the rotation angle of the rotating member 41 .

[0080] When the water hole 42 coincides with the water outlet hole 21 and the water replenishment hole 22 , the rotating member 41 contacts the two stoppers 23 .

[0081] Optional, not shown:

[0082] A one-way valve is installed on the water supply hole 22 , and the one-way valve is used to prevent the water inside the water tank 2 from flowing out through the water supply hole 22 .

[0083] When a one-way valve is provided, the water supply hole 22 can be designed at a position relatively close to the water outlet hole 21 .

[0084] Optional, such as Figure 9 As shown:

[0085] A water supply pipe 24 is installed inside the water tank 2 , one end of the water supply pipe 24 is connected to the water supply hole 22 , and the other end of the water supply pipe 24 is close to the top wall of the water tank 2 .

[0086] The water supply pipe 24 has the same function as the one-way valve, both of which are used to prevent the water inside the water tank 2 from flowing out through the water supply hole 22, so that the water supply hole 22 and the water outlet hole 21 can both be designed near the bottom of the water tank 2.

[0087] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the spirit and scope of protection of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the scope of protection of the embodiments of the present invention.

Claims

1. An emergency rescue system for elevator car failure, characterized in that: include : water tank (2), trigger rod (3), valve (4) and channel (6); The channel (6) is installed on the inner wall of the elevator shaft (1) in a vertical direction, and the channel (6) allows the ball (5) to fall along the direction of gravity. The entrance of the channel (6) passes through the wall of the elevator shaft (1) and extends to the outer wall of the elevator shaft (1); The water tank (2) is installed on the elevator car (11), liquid is pre-stored in the water tank (2) to form a counterweight, and the valve (4) is installed at the bottom end of the water tank (2) and connects the inner and outer sides of the water tank (2); One end of the trigger rod (3) is rotatably connected to the water tank (2), and the other end of the trigger rod (3) extends toward the inner wall of the elevator shaft (1) and extends into the channel (6). The trigger rod (3) can move vertically in the channel (6) without any obstacles, and the operating part of the valve (4) is transmission-connected to the trigger rod (3); When the elevator fails and the elevator car (11) and the counterweight device (12) are in weight balance, the rolling ball (5) is operated to enter the interior of the channel (6) along the entrance of the channel (6) and then fall and hit the trigger rod (3). The trigger rod (3) rotates to open the valve (4), and the liquid inside the water tank (2) is thrown into the elevator shaft (1). The counterweight disappears and the weight balance between the elevator car (11) and the counterweight device (12) is released. The side wall of the water tank (2) is provided with a water outlet hole (21); The valve (4) includes a rotating member (41), the rotating member (41) is connected to the water tank (2) in a rotational manner around a horizontal axis, the proximal end of the trigger rod (3) is fixedly connected to the rotating member (41) and is an integral member, the trigger rod (3) is a hollow tube, and a water hole (42) connected to the distal end of the trigger rod (3) is formed on a surface of the rotating member (41) that contacts the water tank (2); When the trigger rod (3) is in an initial position, the rotating member (41) closes the water outlet (21); after the trigger rod (3) collides with the rolling ball (5), the rotating member (41) rotates so that the water outlet (21) and the water passage (42) overlap, and the liquid in the water tank (2) is thrown into the interior of the elevator shaft (1) through the water outlet (21), the water passage (42) and the trigger rod (3).

2. The elevator car failure emergency rescue system according to claim 1, characterized in that: The channel (6) comprises: a plurality of pipes (62) connected end to end along the direction of gravity; Each of the pipes (62) corresponds to one floor of the building, and the bottom end of each of the pipes (62) is connected to the top end of the pipe (62) located on the next floor of the building; An inlet and outlet hole (61) is provided on each floor of the building and passes through the wall of the elevator shaft (1) and is connected to the end of the pipe (62). The bottom edge of the inlet and outlet hole (61) is connected to an inclined plate (64) extending toward the inside of the pipe (62). The pipe (62) and the inclined plate (64) are both provided with an avoidance opening (65) for avoiding the vertical movement of the trigger rod (3) in the channel (6). The avoidance opening (65) has a size that the rolling ball (5) cannot pass through. The inclined plate (64) is inclined upward, and a gap is left between the side of the inclined plate (64) away from the inlet and outlet hole (61) and the inner wall of the pipe (62) for the rolling ball (5) to pass through; The bottom end of the pipe (62) located on the upper floor of the building is located directly above the inclined plate (64), and the bottom end of the pipe (62) faces the middle of the inclined plate (64).

3. The elevator car failure emergency rescue system according to claim 2, characterized in that: The cross-sectional areas of the middle end and the bottom end of the pipe (62) are the same, the projected area of ​​the inclined plate (64) on the cross-sectional area of ​​the pipe (62) is equal to the cross-sectional area of ​​the bottom end of the pipe (62), and the top end of the pipe (62) is formed with a radially outwardly expanding socket (63), and the cross-sectional area of ​​the socket (63) is equal to twice the cross-sectional area of ​​the bottom end of the pipe (62).

4. The elevator car failure emergency rescue system according to claim 3, characterized in that: The bottom end of each pipe (62) is inserted into the socket (63) of the pipe (62) located on the next floor of the building, and the top end of the socket (63) is higher than the top end of the inclined plate (64).

5. The elevator car failure emergency rescue system according to claim 2, characterized in that: The bottom edge of the inlet and outlet hole (61) is flush with the ground of each floor of the building.

6. The elevator car failure emergency rescue system according to claim 1, characterized in that: A reset block (7) is provided at the bottom of the elevator shaft (1); when the elevator car (11) moves to the bottom of the elevator shaft (1), the bottom of the trigger rod (3) contacts the top of the reset block (7) to restore the initial posture.

7. The elevator car failure emergency rescue system according to claim 1, characterized in that: A water replenishment hole (22) is provided above the water outlet hole (21); when the trigger lever (3) is in an initial posture, the water replenishment hole (22) and the water flow hole (42) overlap.

8. The elevator car failure emergency rescue system according to claim 7, characterized in that: The outer wall of the water tank (2) is provided with two stoppers (23) located on the upper and lower sides of the rotating member (41), and the stoppers (23) are used to limit the rotation angle of the rotating member (41).

9. The elevator car failure emergency rescue system according to claim 7, characterized in that: A one-way valve is installed on the water supply hole (22), and the one-way valve is used to prevent the water inside the water tank (2) from flowing out through the water supply hole (22); or-- A water supply pipe (24) is installed inside the water tank (2), one end of the water supply pipe (24) is connected to the water supply hole (22), and the other end of the water supply pipe (24) is close to the top wall of the water tank (2).

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