Inkjet tracer device for underwater crack detection in dams

Abstract

The invention discloses an inkjet tracer device for underwater crack detection of dams. The device comprises an ink reservoir, an underwater solenoid valve, and a dilution inkjet device, wherein the ink reservoir, the underwater solenoid valve, and the dilution inkjet device are connected in sequence through a PU tube, the ink reservoir contains a high-concentration tracer liquid, the threaded hole of the ink reservoir is connected to the input end of the underwater solenoid valve through the PU tube, the underwater solenoid valve is controlled by an electric control device, when the solenoid valve is opened, the spring I and the water pressure push the piston rod to extrude the high-concentration tracer liquid; the output end of the underwater solenoid valve is connected to the left cavity of the dilution inkjet device through the PU tube; the dilution inkjet device is controlled by a lead screw nut mechanism driven by a stepper motor, and the dilution tracer is discharged from the center of the end cover by a piston push rod for dam crack detection. The invention has a compact structure and simple control, and can easily realize crack detection of the dam body underwater through the entire inkjet tracer device.

Description

Technical Field

[0001] The invention belongs to the field of underwater inkjet devices, and in particular relates to an inkjet tracing device for underwater crack detection of a dam. Background Art

[0002] After a dam has been in use for a long time, cracks will appear due to the effects of water scouring and erosion, causing leakage, which will have a serious impact on the safety of the dam. Therefore, cracks in the dam must be inspected regularly.

[0003] The traditional way to detect leaks is for divers to dive into the water with inkjet devices. Once a dangerous point is found, the valve can be opened, and the high-pressure device on the shore will inject the tracer into the target point, and the waters near the target point will be dyed. If there is a crack, the pressure difference inside and outside the crack will force the dyed water to flow into the crack, so that the crack location can be observed.

[0004] The disadvantages of traditional leak detection methods are as follows: 1) Professional divers need to be hired to perform manual inkjet detection, which is inconvenient to operate and the divers’ diving depth is limited. 2) Divers need to carry the equipment into the water, which is troublesome and heavy. 3) Inkjet operation requires divers to work together with shore personnel, which makes communication inconvenient.

[0005] At present, underwater robots have gradually replaced manual diving observations and become the mainstream method of dam inspection. The robot is equipped with a tracer device and sprays ink near the cracks in the dam. The tracer can quickly diffuse into the cracks in the dam, making it possible to observe and identify the cracks more intuitively and clearly. Summary of the invention

[0006] In order to solve the problems in the background technology, the present invention provides an inkjet tracing device for underwater crack detection of dams, which can conveniently perform tracing detection underwater.

[0007] The technical solution adopted by the present invention is as follows:

[0008] The present invention comprises an ink reservoir, an underwater solenoid valve and a dilution inkjet device, wherein the ink reservoir, the underwater solenoid valve and the dilution inkjet device are sequentially connected through a PU tube, and the underwater solenoid valve is connected to an electric control device;

[0009] The ink reservoir comprises a front cover, a cylinder, a rear cover, a piston rod and a spring I. The front cover and the rear cover are connected to the left and right sides of the cylinder by bolts. A piston rod is slidably embedded in the cylinder. The piston rod consists of a piston I and a piston push rod I. One end of the piston push rod I is connected to the piston I, and the other end of the piston push rod I extends out of the rear cover through a circular hole opened in the rear cover. The piston push rod I located inside the cylinder is sleeved with a spring I. One end of the spring I is connected to the piston I, and the other end of the spring I is connected to the rear cover. A PU tube is connected between a threaded hole provided in the center of the front cover of the ink reservoir and one end of the underwater solenoid valve. A high-concentration tracer liquid is stored in the area surrounded by the front cover, the piston I and the cylinder. The piston rod pushes the high-concentration tracer to be squeezed out from the center of the front cover and then transported to the underwater solenoid valve through the PU tube.

[0010] The dilution inkjet device comprises an end cover, a left cavity, a middle cavity, a right cavity and a base. The end cover, the left cavity, the middle cavity, the right cavity and the base are coaxially connected in sequence through bolts. A block I is connected between the end cover and the left cavity, and a block II is connected between the left cavity and the middle cavity. Through holes are opened in the middle of the block I and the block II. A boss is provided in the middle of one side of the end cover away from the block I. The inside of the boss is a through groove that runs through the left and right sides. A support plate I with a circular hole in the middle is provided in the middle of the inside of the boss to separate the through groove in the boss into two left and right grooves. A spring II is installed in the groove between the support plate I and the block II, that is, close to the block I. A plug is installed between the spring II and the block II to block the through hole in the middle of the block II.

[0011] A piston II is slidably installed inside the left cavity, one end of a spring III is fixedly connected to a stopper I, and the other end of a spring III is fixedly connected to a piston II. A through hole is opened in the middle of the piston II, and a left one-way valve is embedded in the through hole. Support plates II, III and IV are respectively fixed in the middle of the left cavity, the middle cavity and the right cavity. The area surrounded by the stopper I, the left cavity and the piston II is the cavity I, the area surrounded by the piston II, the left cavity and the support plate II is the cavity II, the area surrounded by the support plate II, the left cavity and the stopper II is the cavity III, the area surrounded by the stopper II, the middle cavity and the support plate III is the cavity IV, the area surrounded by the support plate III, the middle cavity, the right cavity and the support plate IV is the cavity V, and the area surrounded by the support plate IV, the right cavity and the base is the cavity VI;

[0012] One end of the screw rod is fixedly connected to the support plate III, and the other end of the screw rod passes through the support plate IV and is connected to the output shaft of the stepper motor, and the stepper motor is located in the cavity VI; a nut sliding along the screw rod is mounted on the screw rod, and a sliding rod frame is connected to the side of the nut close to the support plate III by a bolt, and the sliding rod frame passes through the support plate III and slides in the cavity IV and the cavity V driven by the nut, and a piston push rod II is connected between the end of the sliding rod frame located in the cavity IV and the left one-way valve, and a right one-way valve mounted on the piston push rod II is embedded in the middle through hole of the block II, and a spring IV is connected between the support plate II and the right one-way valve, and the spring IV is mounted on the piston push rod II; two through holes are opened on the upper and lower sides of the cavity IV to communicate with the external water flow, and the other end of the underwater solenoid valve is connected to the through hole opened on the upper side of the cavity III through a PU tube.

[0013] The working process of the inkjet tracer device is as follows:

[0014] Step S1: Open the underwater solenoid valve, and the spring I pushes the piston rod to move toward the front cover. The high-concentration tracer liquid flows into the left cavity of the dilution inkjet device through the PU tube and the solenoid valve, and then the underwater solenoid valve is quickly closed;

[0015] Step S2: The piston push rod II connected to the nut moves toward the end cover driven by the stepper motor, thereby pushing the piston II to compress the spring II. When the high pressure in the cavity I is greater than the spring preload of the spring II, the plug is forced to be pushed out, the through hole of the stopper I is opened, and the air in the cavity I is exhausted through the through hole of the stopper I.

[0016] Step S3: When the piston II moves toward the end cover, the internal pressure of the cavity II decreases. When the pressure difference between the middle cavity and the cavity II is greater than the elastic force of the spring IV, the right one-way valve is pushed to open, and the external water flows through the upper and lower through holes in the cavity IV and the block II into the left cavity, so that the high-concentration tracer liquid in the cavity II is diluted to a diluted tracer, until the pressure difference between the middle cavity and the cavity II reaches equilibrium, and the right one-way valve is closed;

[0017] Step S4: Control the piston push rod II to move toward the base through the stepper motor, and the pressure in the cavity II gradually increases until the pressure in the cavity II is equal to the elastic force of the spring III, then the piston II stops moving toward the base, and the piston push rod II continues to move toward the base, and the left one-way valve connected to the piston push rod II gradually opens, and the diluted tracer in the cavity II flows into the cavity I through the middle through hole of the piston II. This process can appropriately speed up the movement speed of the piston push rod to ensure that the left one-way valve opens as soon as possible; at the same time, since the pressure in the cavity II only increases but does not decrease, the right one-way valve is always in a closed state;

[0018] Step S5: Repeat steps S1-S4 until the detection is completed. When the piston push rod II moves toward the end cover again, the high pressure in the cavity I pushes out the plug, the through hole of the block I opens, and the diluted tracer in the cavity I is squeezed out to the outside through the through hole of the block I. At the same time, the dilution of the next high-concentration tracer liquid is completed.

[0019] The ink reservoir and the underwater solenoid valve are located at the same height, and the water pressures at both ends of the tracer in the PU tube connecting the ink reservoir and the underwater solenoid valve are approximately equal; after the underwater solenoid valve is opened, the piston push rod Ⅰ of the piston rod is only subjected to the spring force of spring Ⅰ when the water pressures at both ends of the PU tube are offset, and the high-concentration tracer is discharged outward under the push of the spring force, which is independent of the external water depth and water pressure.

[0020] The piston rod and spring I of the ink reservoir are suitable for rigid materials or soft materials, such as compressed soft capsules.

[0021] The piston I of the piston rod in the ink reservoir is sealed with the cylinder through two layers of piston sealing rings, and the piston II in the dilution inkjet device is sealed with the left cavity through two layers of piston sealing rings.

[0022] The stepper motor is connected to the right cavity through bolts.

[0023] The high-concentration tracer liquid is bright red food coloring.

[0024] Beneficial effects of the present invention:

[0025] The present invention has a compact structure, fewer components and is easy to operate. It only requires electronic control of the on and off of the solenoid valve and the left and right movement of the lead screw nut through a stepper motor to realize a tracing means for detecting cracks in the dam body, and is not affected by water depth (external water pressure) when in use.

[0026] The present invention is an independent device and can be carried on an underwater robot such as a manned submersible for operation, so it is convenient to use.

[0027] The invention has small size, light weight and high efficiency. It only needs to carry highly concentrated tracers into the water, and the water used for dilution is external water. Therefore, a small amount of concentrated tracers can still produce a large amount of diluted dyed water after being mixed and diluted with external water. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the overall connection diagram of the present invention.

[0029] Figure 2 It is a schematic structural diagram of the ink reservoir of the present invention.

[0030] Figure 3 It is a schematic structural diagram of the dilution inkjet device of the present invention.

[0031] Figure 4 The figure shows the working process of the inkjet tracing device of the present invention.

[0032] In the figure: 1-ink reservoir, 2-underwater solenoid valve, 3-PU tube, 4-dilution inkjet device, 5-front cover, 6-cylinder, 7-high concentration tracer liquid, 8-piston rod, 9-spring I, 10-rear cover, 11-end cover, 12-spring II, 13-plug, 14-stopper I, 15-spring III, 16-dilution tracer, 17-left cavity, 18-piston II, 19-left one-way valve, 21-piston push rod II, 22 -spring IV, 23-block II, 24-right one-way valve, 25-water, 26-middle cavity, 27-slide rod, 28-nut, 29-screw rod, 30-right cavity, 31-stepping motor, 32-base, 33-support plate I, 34-support plate II, 35-support plate III, 36-support plate IV, 37-cavity I, 38-cavity II, 39-cavity III, 40-cavity IV, 41-cavity V, 42-cavity VI. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments:

[0034] like Figure 1 As shown, the present invention includes an ink reservoir 1, an underwater solenoid valve 2 and a dilution inkjet device 4. The ink reservoir 1, the underwater solenoid valve 2 and the dilution inkjet device 4 are connected in sequence through a PU tube 3, and the underwater solenoid valve 2 is connected to an electronic control device.

[0035] like Figure 2 As shown, the ink reservoir 1 includes a front cover 5, a cylinder 6, a rear cover 10, a piston rod 8 and a spring Ⅰ9. The front cover 5 and the rear cover 10 are connected to the left and right sides of the cylinder 6 by bolts. The piston rod 8 is slidably embedded in the cylinder 6. The piston rod 8 consists of a piston Ⅰ and a piston push rod Ⅰ. One end of the piston push rod Ⅰ is connected to the piston Ⅰ, and the other end of the piston push rod Ⅰ extends out of the rear cover 10 through a circular hole opened in the rear cover 10. The piston push rod Ⅰ located inside the cylinder 6 is sleeved with a spring Ⅰ9, one end of the spring Ⅰ9 is connected to the piston Ⅰ, and the other end of the spring Ⅰ9 is connected to the rear cover 10; a PU tube 3 is connected between the threaded hole provided in the center of the front cover 5 of the ink reservoir 1 and one end of the underwater solenoid valve 2, and a high-concentration tracer liquid 7 is stored in the area surrounded by the front cover 5, the piston Ⅰ and the cylinder 6. The piston rod 8 pushes the high-concentration tracer liquid 7 to be squeezed out from the center of the front cover 5 and then transported to the underwater solenoid valve 2 through the PU tube 3.

[0036] like Figure 3As shown, the dilution inkjet device 4 includes an end cover 11, a left cavity 17, a middle cavity 26, and a right cavity 30. The end cover 11, the left cavity 17, the middle cavity 26, the right cavity 30, and the base 32 are coaxially connected in sequence by bolts. A block I14 is connected between the end cover 11 and the left cavity 17, and a block II23 is connected between the left cavity 17 and the middle cavity 26. Through holes are opened in the middle of the block I14 and the block II23; a boss is provided in the middle of one side of the end cover 11 away from the block I14, and the inside of the boss is a through groove running through the left and right sides. A support plate I33 with a circular hole in the middle is provided in the middle of the boss to separate the internal groove of the boss into two left and right grooves, and a spring II12 is installed in the groove between the support plate I33 and the block II23, that is, close to the block I14, and a plug 13 for blocking the middle through hole of the block II23 is installed between the spring II12 and the block II23.

[0037] like Figure 3 As shown, a piston II 18 is slidably installed inside the left cavity 17, one end of the spring III 15 is fixedly connected to the stopper I 14, and the other end of the spring III 15 is fixedly connected to the piston II 18. A through hole is opened in the middle of the piston II 18, and a left one-way valve 19 is embedded in the through hole. Support plates II 34, III 35 and IV 36 are respectively fixed in the middle of the left cavity 17, the middle cavity 26 and the right cavity 30; one end of the screw rod 29 is fixedly connected to the support plate III 35, and the other end of the screw rod 29 passes through the support plate IV 36 and is connected to the output shaft of the stepper motor 31. The stepper motor 31 is located in the right cavity of the right cavity 30; a nut 28 sliding along the screw rod 29 is mounted on the screw rod 29, and the nut 28 A sliding rod frame is connected to the side close to the support plate III35 by bolts. The sliding rod frame passes through the support plate III35 and slides in the cavity IV40 and the cavity V41 driven by the nut 28. A piston push rod II21 is connected between the end of the sliding rod frame located in the cavity IV40 and the left one-way valve 19. The right one-way valve 24 mounted on the piston push rod II21 is embedded in the middle through hole of the block II23. A spring IV22 is connected between the support plate II34 and the right one-way valve 24, and the spring IV22 is mounted on the piston push rod II21. Two through holes are opened on the upper and lower sides of the cavity IV40 to communicate with the external water flow. The other end of the underwater solenoid valve 2 is connected to the threaded hole opened on the upper side of the cavity III39 through a PU tube. Example

[0038] Install the ink reservoir 1 and the inkjet dilution device 4 on the shore: put the spring I9 on the piston rod 8 passing through the rear cover 10, the rear cover 10 is fixedly connected to the cylinder 6 by bolts, the front cover 5 is fixedly connected to the cylinder 6 by bolts, and the high-concentration tracer liquid 7 is injected from the threaded hole in the center of the front cover 5 by a syringe, and the PU tube 3 is connected to the threaded hole of the front cover 5 through a quick connector, and the PU tube 3 is connected to one end of the underwater solenoid valve 2, and the other end of the underwater solenoid valve 2 is connected to the inkjet dilution device 4 through the PU tube 3. Put the spring II 12 into the right groove in the center of the end cover and connect the plug 13, fix the left one-way valve 19 and the piston push rod II 21 and insert it into the left cavity 17, then install the piston II 18 and the spring III 15, and connect the end cover 11, the block I 14 and the left cavity 17 by bolts. Put spring II22 on the other end of piston push rod II21 and insert right one-way valve 24, put piston push rod 21 with stopper II23 and hold right one-way valve 24. Slide rod 27 passes through support plate III35 and is fixedly connected with piston push rod II21. Left cavity 17, stopper II23 and middle cavity 26 are connected in sequence by bolts. Screw 29 is connected with nut 28 and then installed into cavity V41, and nut 28 is fixedly connected with slide rod 27 by bolts. Right cavity 30 is connected with middle cavity 26 by bolts, stepper motor 31 is installed from right cavity 30, connected with screw rod 29 and then connected with support plate IV36 in right cavity 30 by bolts, and finally base 32 is connected with right cavity 30 by bolts. After that, only high concentration tracer liquid 7 needs to be injected into the threaded hole of front cover 5 again, without dismantling the whole equipment and reinstalling it.

[0039] The working process of the inkjet tracer device is as follows Figure 4 As shown: the whole device is equipped with an underwater robot to dive underwater for work. When the personnel on the shore find cracks in the dam, the underwater solenoid valve 2 is opened by the electronic control device. After about 1 second, the underwater solenoid valve 2 is immediately closed, so that a small amount of high-concentration tracer liquid 7 enters the dilution inkjet device 4. When used for the first time, the stepper motor 31 is controlled to operate to push the piston push rod II 21 to move left, so that the external water enters the dilution inkjet device 4 to dilute the high-concentration tracer liquid 7. Then the stepper motor 31 is controlled to operate to move the piston push rod 21 to the right, and the diluted tracer 16 is transported to the left side of the piston II 18, that is, the cavity I 37. When the piston push rod II 21 moves to the left next time, the diluted tracer 16 is sprayed out from the center of the end cover 11, and the next high-concentration tracer liquid 7 is diluted at the same time.

Claims

1. An inkjet tracer device for underwater crack detection in dams, characterized in that: It comprises an ink reservoir (1), an underwater solenoid valve (2) and a dilution inkjet device (4), wherein the ink reservoir (1), the underwater solenoid valve (2) and the dilution inkjet device (4) are connected in sequence via a PU tube (3), and the underwater solenoid valve (2) is connected to an electronic control device; The ink reservoir (1) comprises a front cover (5), a cylinder (6), a rear cover (10), a piston rod (8) and a spring I (9). The front cover (5) and the rear cover (10) are connected to the left and right sides of the cylinder (6) by bolts. The cylinder (6) is slidably embedded with a piston rod (8). The piston rod (8) is composed of a piston I and a piston push rod I. One end of the piston push rod I is connected to the piston I, and the other end of the piston push rod I extends out of the rear cover (10) through a circular hole opened in the rear cover (10). The piston push rod I located inside the cylinder (6) is A spring I (9) is mounted, one end of the spring I (9) is connected to the piston I, and the other end of the spring I (9) is connected to the rear cover (10); a PU tube (3) is connected between a threaded hole provided at the center of the front cover (5) of the ink reservoir (1) and one end of the underwater solenoid valve (2); a high-concentration tracer liquid (7) is stored in an area surrounded by the front cover (5), the piston I and the cylinder (6); the piston rod (8) pushes the high-concentration tracer liquid (7) to be squeezed out from the center of the front cover (5) and then transported to the underwater solenoid valve (2) through the PU tube (3); The dilution inkjet device (4) comprises an end cover (11), a left cavity (17), a middle cavity (26), and a right cavity (30). The end cover (11), the left cavity (17), the middle cavity (26), the right cavity (30), and a base (32) are coaxially connected in sequence by bolts. A stopper I (14) is connected between the end cover (11) and the left cavity (17). A stopper II (23) is connected between the left cavity (17) and the middle cavity (26). A through hole is provided on each of the end caps (11) away from the stopper I (14). A boss is provided in the middle of one side of the end cap (11), and a through groove is provided inside the boss. A support plate I (33) with a circular hole in the middle is provided inside the boss to separate the through groove inside the boss into two grooves on the left and right. A spring II (12) is provided in the groove between the support plate I and the stopper II (23), i.e., close to the stopper I (14). A plug (13) is provided between the spring II (12) and the stopper II (23) to block the through hole in the middle of the stopper II (23). A piston II (18) is slidably mounted inside the left cavity (17), one end of a spring III (15) is fixedly connected to a stopper I (14), and the other end of the spring III (15) is fixedly connected to the piston II (18). A through hole is opened in the middle of the piston II (18), and a left check valve (19) is embedded in the through hole. A support plate II (34), a support plate III (35) and a support plate IV (36) are fixed in the middle of the left cavity (17), the middle cavity (26) and the right cavity (30), respectively. The area surrounded by the stopper I (14), the left cavity (17) and the piston II (18) is the cavity I (37). The piston The area enclosed by the left cavity (18), the left cavity (17) and the support plate (34) is cavity (38); the area enclosed by the support plate (34), the left cavity (17) and the block (23) is cavity (39); the area enclosed by the block (23), the middle cavity (26) and the support plate (35) is cavity (40); the area enclosed by the support plate (35), the middle cavity (26), the right cavity (30) and the support plate (36) is cavity (41); the area enclosed by the support plate (36), the right cavity (30) and the base (32) is cavity (42); One end of the screw rod (29) is fixedly connected to the support plate III (35), and the other end of the screw rod (29) passes through the support plate IV and is connected to the output shaft of the stepper motor (31), and the stepper motor (31) is located in the cavity VI (42); a nut (28) sliding along the screw rod (29) is mounted on the screw rod (29), and a sliding rod frame is connected to the side of the nut (28) close to the support plate III (35) by bolts, and the sliding rod frame passes through the support plate III (35) and slides in the cavity IV (40) and the cavity V (41) under the drive of the nut (28), and is located in the cavity IV (40). A piston push rod II (21) is connected between the end of the slide rod frame and the left one-way valve (19); a right one-way valve (24) mounted on the piston push rod II (21) is embedded in the middle through hole of the stopper II (23); a spring IV (22) is connected between the support plate II (34) and the right one-way valve (24), and the spring IV (22) is mounted on the piston push rod II (21); two through holes are opened on the upper and lower sides of the cavity IV (40) to communicate with the external water flow, and the other end of the underwater solenoid valve (2) is connected to the through hole opened on the upper side of the cavity III (39) through the PU tube (3).

2. The inkjet tracer device for underwater crack detection of dams according to claim 1, characterized in that: The working process of the inkjet tracer device is as follows: Step S1: Open the underwater solenoid valve (2), the spring I (9) pushes the piston rod (8) to move toward the front cover (5), and the high-concentration tracer liquid (7) flows into the left cavity (17) of the dilution inkjet device (4) through the PU tube (3) and the solenoid valve (2), and then the underwater solenoid valve (2) is quickly closed; Step S2: The piston push rod II (21) connected to the nut (28) moves toward the end cover (11) driven by the stepper motor (31), thereby pushing the piston II (18) to compress the spring II (12). When the high pressure in the cavity I (37) is greater than the spring preload force of the spring II (12), the plug (13) is forced to be pushed out, the through hole of the stopper I (14) is opened, and the air in the cavity I (37) is exhausted through the through hole of the stopper I (14); Step S3: When the piston II (18) moves toward the end cover (11), the internal pressure of the cavity II (38) decreases. When the internal pressure difference between the middle cavity (26) and the cavity II (38) is greater than the elastic force of the spring IV (22), the right one-way valve (24) is pushed to open, and the external water flows through the upper and lower through holes in the cavity IV (40) and the stopper II (23) into the left cavity (17), so that the high-concentration tracer liquid (7) in the cavity II (38) is diluted to a diluted tracer (16), until the internal pressure difference between the middle cavity (26) and the cavity II (38) reaches equilibrium, and the right one-way valve (24) is closed; Step S4: The piston push rod II (21) is controlled by the stepper motor (31) to move toward the base (32), and the pressure in the cavity II (38) gradually increases until the pressure in the cavity II (38) is equal to the elastic force of the spring III (15), and the piston II (18) stops moving toward the base (32), and the piston push rod II (21) continues to move toward the base (32), and the left one-way valve (19) connected to the piston push rod II (21) gradually opens, and the diluted tracer (16) in the cavity II (38) flows into the cavity I (37) through the middle through hole of the piston II (18); Step S5: Repeat steps S1-S4. When the piston push rod II (21) moves toward the end cover (11) again, the high pressure in the cavity I (37) pushes out the plug (13), the through hole of the block I (14) opens, and the diluted tracer (16) in the cavity I (37) is squeezed out to the outside through the through hole of the block I (14). At the same time, the next dilution of the high-concentration tracer liquid (7) is completed.

3. The inkjet tracer device for underwater crack detection of dams according to claim 2, characterized in that: The ink reservoir (1) and the underwater electromagnetic valve (2) are located at the same height, and the water pressures at both ends of the tracer in the PU tube (3) connecting the ink reservoir (1) and the underwater electromagnetic valve (2) are approximately equal; after the underwater electromagnetic valve (2) is opened, the piston push rod I of the piston rod (8) is only subjected to the spring force of the spring I (9) when the water pressures at both ends of the PU tube (3) are offset, and the high-concentration tracer liquid (7) is discharged outward under the push of the spring force, regardless of the external water depth and water pressure.

4. The inkjet tracer device for underwater crack detection of dams according to claim 1, characterized in that: The piston rod (8) and spring I (9) of the ink reservoir (1) are suitable for rigid materials or soft materials.

5. The inkjet tracer device for underwater crack detection of dams according to claim 1, characterized in that: The piston I of the piston rod (8) in the ink reservoir (1) and the cylinder (6) are sealed by two layers of piston sealing rings, and the piston II (18) in the dilution inkjet device (4) and the left cavity (17) are sealed by two layers of piston sealing rings.

6. The inkjet tracer device for underwater crack detection of dams according to claim 1, characterized in that: The stepping motor (31) is connected to the right cavity (30) via bolts.

7. The inkjet tracer device for underwater crack detection of dams according to claim 1, characterized in that: The high concentration tracer liquid (7) is bright red food coloring.

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