A pure hydraulic impact hammer

Abstract

The utility model discloses a kind of pure hydraulic impact hammers, it is related to impact hammer technical field, including main body structure, the output end of main body structure is equipped with drill rod, the stroke cavity for driving piston movement is opened in main body structure, the side of stroke cavity is opened to front cavity towards drill rod, front cavity is connected with first circulating oil circuit, the side of stroke cavity is opened to rear cavity away from drill rod, rear cavity is connected with second circulating oil circuit;Wherein, main body structure outside side is also equipped with energy accumulator structure, one end of energy accumulator structure is connected with first circulating oil circuit, for storing high-pressure oil input into front cavity, its other end is connected with second circulating oil circuit, for high-pressure oil is delivered to rear cavity;The utility model discards nitrogen chamber structure for energy storage or auxiliary drive in existing impact hammer, by optimizing hydraulic system design, only rely on hydraulic energy can realize the efficient reciprocating motion of piston and impact work, form the pure hydraulic drive mode in true sense.

Description

Technical Field

[0001] This utility model relates to the field of impact hammer technology, and in particular to a pure hydraulic impact hammer. Background Technology

[0002] Impact hammers are engineering machinery attachments widely used in construction, mining, road maintenance, and other fields, serving as key supporting devices for main engineering machinery (such as excavators and loaders). Hydraulic impact hammers are engineering equipment that uses a hydraulic system as a power source to achieve functions such as pile foundation construction and rock breaking through instantaneous impact force. Their core principle lies in using hydraulic energy to drive the hammer core's movement, and achieving diverse impact effects through different structural designs.

[0003] The hydraulic impact hammer features a nitrogen chamber at the rear of the impact piston, utilizing the compressibility of nitrogen to store and release energy. During the piston's return stroke, hydraulic oil pushes the piston backward, compressing the nitrogen in the chamber and converting hydraulic energy into the elastic potential energy of the nitrogen. During the stroke phase, the compressed nitrogen expands and performs work, working together with the hydraulic oil to accelerate the piston's descent, creating a "nitrogen explosion" effect.

[0004] Currently, existing hydraulic impact hammers with nitrogen chambers pose a risk of nitrogen leakage, which can lead to decreased equipment performance or even damage. If nitrogen is not used for impact, the piston's stroke force is insufficient to meet practical application requirements, resulting in poor crushing force. Utility Model Content

[0005] This utility model provides a purely hydraulic impact hammer, which can solve the following problems existing in the prior art: Current hydraulic impact hammers use nitrogen for the stroke, but nitrogen is prone to leakage during application, affecting the normal operation of the impact hammer. If nitrogen is removed, the piston's stroke force will be insufficient.

[0006] A pure hydraulic impact hammer includes a main structure, the output end of which is provided with a chisel, and a stroke chamber for driving piston movement is provided in the main structure. A front chamber is provided in the stroke chamber on the side closer to the chisel and is connected to a first circulating oil circuit. A rear chamber is provided in the stroke chamber on the side away from the chisel and is connected to a second circulating oil circuit. The main structure is also provided with an accumulator structure on its outer side. One end of the accumulator structure is connected to the first circulation oil circuit to store the high-pressure oil input to the front chamber, and the other end is connected to the second circulation oil circuit to transport the high-pressure oil to the rear chamber.

[0007] Preferably, the main structure includes a middle cylinder body, a stroke chamber is opened in the middle cylinder body, one end of the middle cylinder body is connected to the lower cylinder body, a chisel is set in the lower cylinder body, and a rear cover is connected to the end of the middle cylinder body away from the lower cylinder body. The rear cover, the middle cylinder body, and the lower cylinder body are fixedly connected by several sets of bolts.

[0008] Preferably, the accumulator structure is a cup-type accumulator, and the accumulator structure is fixed to the outside of the middle cylinder body; The accumulator structure includes an accumulator housing, inside which is a cup structure. The cup structure divides the inner cavity of the accumulator housing into a compression chamber and an oil storage chamber. The oil storage chamber is connected to the front chamber through an energy storage channel opened on the middle cylinder.

[0009] Preferably, the middle cylinder is also provided with a reversing valve, which is connected to the second circulation oil circuit through a switching module to adjust the second circulation oil circuit to extract hydraulic oil from the rear cavity or input hydraulic oil into the rear cavity.

[0010] Preferably, the first circulating oil circuit includes a first oil delivery channel opened on the middle cylinder block, one end of the first oil delivery channel is connected to the front cavity, and the other end is connected to the oil pump through the first oil delivery pipeline.

[0011] Preferably, the second circulating oil circuit includes a second oil delivery channel opened on the middle cylinder block, one end of the second oil delivery channel is connected to the rear cavity, and the other end is connected to the reversing valve through the second oil delivery pipeline, and the reversing valve is respectively provided with a first channel and a second channel; The output end of the oil pump is also connected to an oil inlet pipeline, and the switching module is used to switch the second channel to be connected to the oil storage tank or to switch the first channel to be connected to the oil inlet pipeline.

[0012] Preferably, the cylinder block has a circular groove for embedding a reversing valve, the reversing valve is slidably embedded in the circular groove, and the switching module includes an adjusting pipe connected to the first oil supply line, the other end of the adjusting pipe being connected to the bottom of the circular groove.

[0013] Preferably, the switching module further includes a third oil supply pipeline connected to the top of the circular groove, and a third oil supply channel is also provided on the middle cylinder between the first oil supply channel and the second oil supply channel, and the third oil supply pipeline is connected to the third oil supply channel.

[0014] Preferably, the area of ​​the upper end face of the reversing valve is greater than the area of ​​the lower end face.

[0015] Preferably, a fourth oil delivery channel is also provided on the middle cylinder block on one side of the third oil delivery channel. The fourth oil delivery channel is located on the side closer to the second oil delivery channel, and the second oil delivery channel is connected to the oil storage tank through the fourth oil delivery pipeline. The piston is also provided with an annular groove.

[0016] This utility model provides a purely hydraulic impact hammer, which has the following beneficial effects: 1) By setting up an accumulator structure, in actual application, when the first circulation oil circuit delivers high-pressure oil to the front chamber, in order to ensure that the piston can move upward stably and quickly in the stroke chamber, it is usually necessary to input excess oil into the front chamber. Therefore, this excess oil can be temporarily stored in the accumulator structure. Correspondingly, when driving the piston to perform a stroke, the hydraulic oil located in the accumulator structure can be delivered to the rear chamber through the second circulation oil circuit to meet the flow requirements of the piston stroke process, avoid the phenomenon of the hydraulic pump compromising the output flow and the hydraulic system overflow loss during the piston return phase, so as to increase the impact force of the piston on the chisel and improve the breaking stability of the chisel. 2) The input flow rate of the first circulation oil circuit of this utility model is usually greater than the actual flow rate required for the piston return stroke, which leads to an increase in system pressure. The excess oil enters the accumulator structure, which prevents the main structure from being damaged by excessive pressure for a long time and extends its service life. When the piston reverses or the system pressure fluctuates, the accumulator structure can also absorb hydraulic shock, stabilize the system pressure, and reduce vibration and noise. 3) The reciprocating movement of the directional valve of this utility model controls the piston to change its direction of movement. At the beginning and end of each stroke, the piston will open or close the control oil circuit of the directional valve to cause the valve core to complete the reversing, forming a cyclic working mode. This utility model abandons the nitrogen chamber structure used for energy storage or auxiliary drive in the existing impact hammer. By optimizing the hydraulic system design, the piston can achieve efficient reciprocating motion and impact work by relying solely on hydraulic energy, forming a truly pure hydraulic drive mode. Attached Figure Description

[0017] Figure 1 A three-dimensional structural diagram of a purely hydraulic impact hammer provided by this utility model. Figure 1 ; Figure 2 A three-dimensional structural diagram of a purely hydraulic impact hammer provided by this utility model. Figure 2 ; Figure 3 A cross-sectional view of a purely hydraulic impact hammer provided by this utility model. Figure 1 ; Figure 4 A cross-sectional view of a purely hydraulic impact hammer provided by this utility model. Figure 2 ; Figure 5 A cross-sectional view of a purely hydraulic impact hammer provided by this utility model. Figure 3 ; Figure 6 A cross-sectional view of a purely hydraulic impact hammer provided by this utility model. Figure 4 ; Figure 7A schematic diagram of the piston in a purely hydraulic impact hammer before its return stroke, provided by this utility model; Figure 8 This is a schematic diagram of the piston in a purely hydraulic impact hammer before its stroke, as provided by this utility model.

[0018] Explanation of reference numerals in the attached figures: 1. Main structure; 2. Lower cylinder block; 3. Accumulator structure; 4. Piston; 5. Reversing valve; 101. Rear cover; 102. Circular groove; 103. Oil inlet; 104. Oil outlet; 105. Breather plug; 106. Bolt; 107. Middle cylinder block; 108. Annular groove; 201. Grease fitting; 202. Chisel rod; 203. Inner sleeve; 204. Outer sleeve; 301. Leather cup structure; 302. Compression chamber; 303. Accumulator channel; 401. Piston ring ; 402, Front chamber; 403, Rear chamber; 404, Third oil delivery channel; 405, Fourth oil delivery channel; 406, Second oil delivery channel; 407, First oil delivery channel; 501, Regulating pipeline; 502, Third oil delivery pipeline; 503, Fourth oil delivery pipeline; 504, Oil storage tank; 505, First channel; 506, Second channel; 507, Oil pump; 508, First oil delivery pipeline; 509, Second oil delivery pipeline; 510, Oil inlet pipeline. Detailed Implementation

[0019] The specific embodiments of this utility model are described in detail below, but it should be understood that the protection scope of this utility model is not limited to the specific embodiments.

[0020] Example 1 like Figures 1 to 3As shown in the figure, this utility model provides a pure hydraulic impact hammer, including a main structure 1. The output end of the main structure 1 is provided with a chisel 202 for crushing. A stroke chamber for driving a piston 4 is formed within the main structure 1. A front chamber 402 is formed in the stroke chamber on the side facing the chisel 202, and the front chamber 402 is connected to a first circulating oil circuit. A rear chamber 403 is formed in the filling chamber on the side away from the chisel 202, and the rear chamber 403 is connected to a second circulating oil circuit. Specifically, in this embodiment, initially, the piston 4 is located in the filling chamber on the side facing the chisel 202. When a crushing task is required, high-pressure oil can be input into the front chamber 402 through the first circulating oil circuit. During this process, the second circulation oil circuit discharges the high-pressure oil stored in the rear chamber 403. Based on the pressure of the high-pressure oil in the front chamber 402, the piston 4 can be driven to move away from the chisel 202 in the stroke chamber. When the piston 4 moves to the limit position, this embodiment can input high-pressure oil into the rear chamber 403 through the second circulation oil circuit. During this process, the first circulation oil circuit discharges the high-pressure oil in the front chamber 402. Based on the pressure of the high-pressure oil in the rear chamber 403, the piston 4 can be driven to move towards the chisel 202 in the stroke chamber, thereby striking the chisel 202 and outputting a punch. By repeating this cycle, the chisel 202 can be repeatedly struck, and the chisel 202 can be used for crushing.

[0021] In addition, the stroke chamber is provided with a piston ring 401 for cooperating with the piston 4. This is existing technology, and its principle and specific structure will not be described in detail.

[0022] As a further embodiment, an accumulator structure 3 is also provided on the outside of the main structure 1. One end of the accumulator structure 3 is connected to the first circulation oil circuit to store the high-pressure oil input to the front chamber 402, and the other end is connected to the second circulation oil circuit to transport the high-pressure oil to the rear chamber 403. It can be noted that by setting the accumulator structure 3 in this embodiment, in actual application, when the first circulation oil circuit delivers high-pressure oil to the front chamber 402, in order to ensure that the piston 4 can move upward stably and quickly in the stroke chamber, it is usually necessary to input excess oil into the front chamber 402. Therefore, this excess oil can be temporarily stored in the accumulator structure 3. Correspondingly, when driving the piston 4 to perform a stroke, the hydraulic oil located in the accumulator structure 3 can be transported to the rear chamber 403 through the second circulation oil circuit to meet the flow requirements of the piston 4 during the stroke process, avoid the phenomenon of the hydraulic pump compromising the output flow and the hydraulic system overflow loss during the return stroke of the piston 4, so as to increase the impact force of the piston 4 on the chisel 202 and improve the breaking stability of the chisel 202. It should also be noted that the input flow rate of the first circulation oil circuit is usually greater than the actual flow rate required for the piston return stroke, which leads to an increase in system pressure. The excess oil enters the accumulator structure 3, which prevents the main structure 1 from being damaged due to excessive pressure over a long period of time and extends its service life. At the same time, when piston 4 reverses or system pressure fluctuates, accumulator structure 3 can also absorb hydraulic shock, stabilize system pressure, and reduce vibration and noise.

[0023] Example 2 Based on Embodiment 1, the main structure 1 of this embodiment includes a middle cylinder 107, a stroke chamber is opened in the middle cylinder 107, one end of the middle cylinder 107 is connected to the lower cylinder 2, the chisel 202 is disposed in the lower cylinder 2, and a rear cover 101 is connected to the end of the middle cylinder 107 away from the lower cylinder 2. The rear cover 101, the middle cylinder 107 and the lower cylinder 2 are fixedly connected by several sets of bolts 106. Specifically, in this embodiment, the rear cover 101, the middle cylinder 107 and the lower cylinder 2 are fixedly connected by four sets of bolts 106 to facilitate the disassembly and assembly of the main structure 1.

[0024] In this embodiment, please refer to Figures 4-6 In this embodiment, the accumulator structure 3 is a cup-type accumulator. The accumulator structure 3 is fixed to the outside of the middle cylinder body 107. The accumulator structure 3 includes an accumulator housing, and a cup structure 301 is provided inside the accumulator housing. The cup structure 301 divides the inner cavity of the accumulator housing into a compression chamber 302 and an oil storage chamber. The oil storage chamber is connected to the front chamber 402 through an energy storage channel 303 opened on the middle cylinder body 107. It can be noted that the accumulator structure 4 in this embodiment is also fixed to the middle cylinder body 107 by several sets of bolts to facilitate subsequent disassembly and maintenance. It should be noted that during the process of inputting high-pressure oil into the front chamber 402 through the first circulation oil circuit in this embodiment, part of the hydraulic oil enters the oil storage chamber of the accumulator structure 3 through the energy storage channel 303, which can then compress the cup structure 301, so that the cup structure 301 compresses the compression chamber 302. Correspondingly, during the stroke of the piston 4, the compression chamber 302 and the cup structure 301 cooperate to send the hydraulic oil in the oil storage chamber to the second circulation oil circuit to compensate for the flow required by the piston 4 during the stroke.

[0025] Furthermore, this embodiment can also store nitrogen in the compression chamber 302. When the hydraulic oil applies a pressure to the cup structure 301 protruding towards the compression chamber 302, the nitrogen in the compression chamber 302 can be compressed. This allows the hydraulic oil in the storage chamber to be quickly expelled during the subsequent stroke through the cup structure 301 and the nitrogen. Correspondingly, when storing nitrogen in the compression chamber 302 in this embodiment, the sealing effect between the cup structure 301 and the accumulator housing prevents easy leakage of nitrogen. At the same time, this embodiment can also provide a nitrogen replenishment port on the accumulator housing. If a nitrogen leak occurs, it can be replenished immediately, making the operation more convenient.

[0026] As one implementation method of this embodiment, please refer to Figures 3-6 The cylinder block 107 is also equipped with a reversing valve 5. The reversing valve 5 is connected to the second circulation oil circuit through a switching module to adjust the second circulation oil circuit to extract or input hydraulic oil into the rear chamber 403. It can be noted that when the piston 4 is in the return state, this embodiment can switch the connection between the reversing valve 5 and the second circulation oil circuit through the switching module to extract the hydraulic oil in the rear chamber 403. Correspondingly, when the piston 4 is in the stroke state, the reversing valve 5 can be switched through the switching module to input hydraulic oil into the rear chamber 403 through the second circulation oil circuit for stroke operation.

[0027] For details, please refer to Figures 6-8 The first circulation oil circuit includes a first oil delivery channel 407 opened on the middle cylinder block 107. One end of the first oil delivery channel 407 is connected to the front chamber 402, and the other end is connected to the oil pump 507 through the first oil delivery pipeline 508. It can be explained that when the piston 4 is returning, the oil pump 507 inputs hydraulic oil into the front chamber 402 through the first oil delivery pipeline 508 and the first oil delivery channel 407 to assist the piston 4 in returning.

[0028] The second circulating oil circuit includes a second oil delivery channel 406 located on the middle cylinder block 107. One end of the second oil delivery channel 406 is connected to the rear chamber 403, and the other end is connected to the reversing valve 5 via a second oil delivery pipeline 509. The reversing valve 5 has a first channel 505 and a second channel 506 respectively. The output end of the oil pump 507 is also connected to an oil inlet pipeline 510. The switching module is used to switch the connection between the second channel 506 and the oil reservoir 504 or to switch the connection between the first channel 505 and the oil inlet pipeline 510. It can be noted that in the initial state, refer to Figure 7 The second channel 506 of the reversing valve 5 is connected to the oil reservoir 504. When the piston 4 is in the return stroke, the hydraulic oil in the rear chamber 403 can be transported to the second oil supply line 509 through the second oil supply channel 406, and then flow back to the oil reservoir 504 through the second channel 506 to realize the circulation of hydraulic oil. Correspondingly, when in the stroke state, the switching module switches the first channel 505 of the reversing valve 5 to be connected to the oil inlet line 510. The oil pump 507 can transport hydraulic oil to the rear chamber 403 through the oil inlet line 510, the first channel 505, the second oil supply line 509 and the second oil supply channel 406 to assist the piston 4 in the stroke operation. Accordingly, in this embodiment, you can refer to Figures 3-5 as well as Figure 7The cylinder block 107 has a circular groove 102 for embedding the directional valve 5. The directional valve 5 is slidably embedded in the circular groove 102. The switching module includes a regulating pipe 501 connected to the first oil supply pipe 508. The other end of the regulating pipe 501 is connected to the bottom of the circular groove 102. It can be explained that during the process of the oil pump 507 supplying oil to the first oil supply pipe 508, some hydraulic oil can enter the bottom of the circular groove 102 through the regulating pipe 501, so that under the action of the hydraulic oil, the directional valve 5 is pushed downward to the limit position. At this time, the second channel 506 of the directional valve 5 is connected to the oil reservoir 504 for oil return (see reference). Figure 7 ); The switching module also includes a third oil supply line 502 connected to the top of the circular groove 102. A third oil supply line 404 is also provided on the middle cylinder 107 between the first oil supply line 407 and the second oil supply line 406. The third oil supply line 502 is connected to the third oil supply line 404. Correspondingly, as the piston 4 returns to its limit position, the front chamber 402 connects to the third oil supply line 404, and hydraulic oil can then be transported to the top of the circular groove 102 through the third oil supply line 404 and the third oil supply line 502. Under the pressure of the hydraulic oil, the directional valve 5 is actuated to move downwards to its limit position within the circular groove 102. The first channel 505 of the reversing valve 5 is connected to the oil inlet pipe 510 to deliver hydraulic oil to the rear chamber 403. Specifically, the reciprocating movement of the reversing valve 5 in this embodiment controls the piston 4 to change its direction of movement. At the beginning and end of each stroke, the piston 4 will open or close the control oil circuit of the reversing valve 5 to cause the valve core to complete the reversing, forming a cyclic working mode. This embodiment abandons the nitrogen chamber structure used for energy storage or auxiliary drive in the existing impact hammer. By optimizing the hydraulic system design, the piston 4 can achieve efficient reciprocating motion and impact work by relying solely on hydraulic energy, forming a truly pure hydraulic drive mode.

[0029] As a further embodiment, when the hydraulic oil in the current cavity 402 is delivered to the top of the circular groove 102, since there is still hydraulic oil at the bottom of the circular groove 102, in order to drive the directional valve 5 to move downward in the circular groove 102, the upper end surface area of ​​the directional valve 5 is larger than the lower end surface area. It can be explained that, since the upper end surface area of ​​the directional valve 5 is larger than the lower end surface area, when hydraulic oil of the same pressure acts on the top and bottom of the directional valve 5 at the same time, the directional valve 5 will move downward along the circular groove 102.

[0030] In this embodiment, to initiate the next cycle of strokes after one stroke is completed, please refer to... Figures 3-5 as well as Figure 7A fourth oil supply channel 405 is also provided on the cylinder body 107 on one side of the third oil supply channel 404. The fourth oil supply channel 405 is located on the side closer to the second oil supply channel 406. The second oil supply channel 406 is connected to the oil storage tank 504 through the fourth oil supply pipeline 503. The piston 4 is also provided with an annular groove 108. It can be explained that during the stroke of the piston 4, when it moves to the limit position, the annular groove 108 is synchronously connected to the third oil supply channel 404 and the fourth oil supply channel 405. Since the fourth oil supply pipeline 503 is connected to the oil storage tank 504, it can relieve the pressure of the third oil supply channel 404. Therefore, the hydraulic oil at the bottom of the circular groove 102 can drive the reversing valve 5 to move upward along the circular groove 102, thereby realizing an oil circuit circulation.

[0031] In addition, the middle cylinder block 107 is provided with an oil inlet 103 and an oil outlet 104. The oil inlet 103 is connected to the oil pump 507 through a pipeline, and the oil outlet 104 is connected to the oil storage tank 504 through a pipeline.

[0032] In one implementation, see [reference needed]. Figures 1-4 The lower cylinder 2 is provided with an inner sleeve 203 and an outer sleeve 204 for installing the drill rod 202, so as to protect the lower cylinder 2 from wear.

[0033] In addition, the middle cylinder 107 is equipped with a breather plug 105 to ensure the air pressure balance of the stroke chamber, and the lower cylinder 2 is equipped with a grease nipple 201 to provide lubrication and sealing for the drill rod 202. It is a "lubricant channel" to reduce wear and protect the core components.

[0034] A method for operating a purely hydraulic impact hammer includes the following steps: Please see Figures 1-4 S1, the first circulation oil circuit inputs high-pressure oil into the front chamber 402. During this process, the second circulation oil circuit discharges the high-pressure oil stored in the rear chamber 403. S2. Based on the pressure of the high-pressure oil in the front chamber 402, the piston 4 is driven to move away from the drill rod 202 in the stroke chamber. S3. After piston 4 moves to its limit position, high-pressure oil is input into the rear chamber 403 through the second circulation oil passage. During this process, the first circulation oil passage discharges the high-pressure oil in the front chamber 402. S4. Based on the pressure of the high-pressure oil in the rear chamber 403, the piston 4 is driven to move in the stroke chamber toward the direction of the drill rod 202 to strike the drill rod 202 and output impact energy, and so on.

[0035] The above-disclosed embodiments are only a few specific examples of the present utility model. However, the embodiments of the present utility model are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present utility model.

Claims

1. A purely hydraulic impact hammer, comprising a main structure (1), wherein the output end of the main structure (1) is provided with a chisel (202), characterized in that, The main structure (1) has a stroke chamber for driving the piston (4) to move. A front chamber (402) is provided on the side of the stroke chamber closer to the drill rod (202). The front chamber (402) is connected to the first circulation oil circuit. A rear chamber (403) is provided on the side of the filling chamber away from the drill rod (202). The rear chamber (403) is connected to the second circulation oil circuit. Among them, the main structure (1) is also provided with an accumulator structure (3) on the outside. One end of the accumulator structure (3) is connected to the first circulating oil circuit to store the high-pressure oil input to the front chamber (402), and the other end is connected to the second circulating oil circuit to transport the high-pressure oil to the rear chamber (403).

2. The pure hydraulic impact hammer as described in claim 1, characterized in that, The main structure (1) includes a middle cylinder (107), a stroke chamber is opened in the middle cylinder (107), one end of the middle cylinder (107) is connected to the lower cylinder (2), a chisel (202) is set in the lower cylinder (2), and a rear cover (101) is connected to the end of the middle cylinder (107) away from the lower cylinder (2). The rear cover (101), the middle cylinder (107) and the lower cylinder (2) are fixedly connected by several sets of bolts (106).

3. The pure hydraulic impact hammer as described in claim 2, characterized in that, The accumulator structure (3) is a cup-type accumulator, and the accumulator structure (3) is fixed to the outside of the middle cylinder (107); The accumulator structure (3) includes an accumulator housing, and a cup structure (301) is provided inside the accumulator housing. The cup structure (301) divides the inner cavity of the accumulator housing into a compression cavity (302) and an oil storage cavity. The oil storage cavity is connected to the front cavity (402) through an energy storage channel (303) opened on the middle cylinder (107).

4. A purely hydraulic impact hammer as described in claim 2, characterized in that, The middle cylinder (107) is also provided with a reversing valve (5). The reversing valve (5) is connected to the second circulation oil circuit through a switching module to adjust the second circulation oil circuit to extract hydraulic oil from the rear cavity (403) or input hydraulic oil into the rear cavity (403).

5. A purely hydraulic impact hammer as described in claim 4, characterized in that, The first circulating oil circuit includes a first oil delivery channel (407) opened on the middle cylinder block (107). One end of the first oil delivery channel (407) is connected to the front cavity (402), and the other end is connected to the oil pump (507) through the first oil delivery pipeline (508).

6. A purely hydraulic impact hammer as described in claim 5, characterized in that, The second circulating oil circuit includes a second oil supply channel (406) opened on the middle cylinder block (107). One end of the second oil supply channel (406) is connected to the rear cavity (403), and the other end is connected to the reversing valve (5) through the second oil supply pipeline (509). The reversing valve (5) is provided with a first channel (505) and a second channel (506). The output end of the oil pump (507) is also connected to the oil inlet pipeline (510). The switching module is used to switch the second channel (506) to be connected to the oil storage tank (504) or to switch the first channel (505) to be connected to the oil inlet pipeline (510).

7. A purely hydraulic impact hammer as described in claim 6, characterized in that, The cylinder block (107) has a circular groove (102) for embedding the reversing valve (5). The reversing valve (5) is slidably embedded in the circular groove (102). The switching module includes an adjusting pipe (501) connected to the first oil supply pipe (508). The other end of the adjusting pipe (501) is connected to the bottom of the circular groove (102).

8. A purely hydraulic impact hammer as described in claim 7, characterized in that, The switching module also includes a third oil supply pipeline (502) connected to the top of the circular groove (102). A third oil supply channel (404) is also provided on the middle cylinder (107) between the first oil supply channel (407) and the second oil supply channel (406). The third oil supply pipeline (502) is connected to the third oil supply channel (404).

9. A purely hydraulic impact hammer as described in claim 8, characterized in that, The upper end surface area of ​​the reversing valve (5) is larger than the lower end surface area.

10. A purely hydraulic impact hammer as described in claim 8, characterized in that, A fourth oil delivery channel (405) is also provided on the middle cylinder (107) on one side of the third oil delivery channel (404). The fourth oil delivery channel (405) is located on the side closer to the second oil delivery channel (406). The second oil delivery channel (406) is connected to the oil storage tank (504) through the fourth oil delivery pipeline (503). Among them, the piston (4) is also provided with an annular groove (108).

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