Pneumatic down-the-hole hammer

Abstract

The present application relates to the technical field of pneumatic impactor for drilling, in particular to a pneumatic DTH hammer, the air chamber in the inner cylinder is separated by the structure of the piston, and the fluid space in the outer cylinder is formed by the space around the piston, which makes it unnecessary to open fluid channels on the wall of the piston and the wall of the outer cylinder, and the compressed air can alternately enter different air chambers to drive the piston reciprocating, which not only reduces the manufacturing cost and process difficulty based on the simple structure, but also greatly improves the strength of the piston to bear the load, thereby significantly increasing the service life of the piston part and the whole DTH hammer; moreover, based on the unique fluid channel path of the present application, the impact final speed and impact frequency of the piston are relatively high under the condition of ensuring the normal work of the piston.

Description

Technical Field

[0001] This invention relates to pneumatic impactors for drilling, and particularly to a pneumatic down-the-hole hammer suitable for various types of boreholes for rapid drilling in hard rock. Background Technology

[0002] The pneumatic down-the-hole hammer, also known as a pneumatic impactor, is a highly efficient hard rock drilling tool, widely used for its advantages such as high drilling efficiency and good borehole quality. It works by using its own air distribution system to alternately supply compressed air to the front and rear chambers of the piston, causing the piston to reciprocate continuously. When the piston moves downwards and impacts the drill bit, the carbide ball teeth at the end of the drill bit break the rock. Furthermore, the down-the-hole hammer is connected to the bottom of the drill rod during use. The drill rig rotates the drill rod, which in turn rotates the down-the-hole hammer, thus breaking the rock and creating drilling progress.

[0003] In existing technologies, to drive the piston to reciprocate using the pressure difference created by compressed air in different chambers, fluid channels are typically created on the piston wall and / or the cylinder wall (including the inner and outer cylinders) to allow gas to alternately enter different chambers. This is a common practice in the field of down-the-hole hammers. However, this approach has the following technical problems: First, the work done by the piston in the cylinder generates a large impact load. Due to the fluid channels on the piston and cylinder walls, under high-intensity operation, the piston may easily develop cracks or fissures at the fluid channels, affecting the normal operation of the down-the-hole hammer and its service life. Second, the existing fluid channel structure is relatively complex, which greatly increases manufacturing costs and the difficulty of the manufacturing process. In addition, the practice of setting narrow fluid channels on the piston or cylinder wall prolongs the path of compressed air alternately entering the front and rear chambers of the piston. This process may cause air pressure loss, affecting the instantaneous response to air pressure changes in the front and rear chambers of the piston, and consequently affecting the piston's final impact frequency and impact velocity.

[0004] Therefore, it is particularly important to ensure that compressed air alternately enters different chambers so that the piston is driven to reciprocate while avoiding or reducing the need for slotting on the piston wall and / or cylinder wall. Summary of the Invention

[0005] In view of this, the present invention provides a pneumatic down-the-hole hammer that eliminates the need for fluid channels on the piston wall and the outer cylinder wall, enabling compressed air to alternately enter different air chambers to drive the piston in reciprocating motion. This not only reduces manufacturing costs and process difficulty due to the simple structure, but also greatly improves the piston's load-bearing strength, thereby significantly extending the service life of the piston component and the overall down-the-hole hammer. Moreover, based on the unique fluid channel path of the present invention, the piston's impact terminal velocity and impact frequency are relatively high while ensuring normal piston operation.

[0006] This invention discloses a pneumatic down-the-hole hammer, comprising an outer cylinder, an inner cylinder, an impact piston, and a drill bit body. The drill bit body is attached to the end of the outer cylinder. The inner cylinder is axially positioned inside the outer cylinder. The impact piston is located inside the outer cylinder, and its upper part is located in the inner cylinder cavity of the inner cylinder. The impact piston can be driven by the air pressure difference to move axially relative to the outer and inner cylinders. The piston section of the impact piston in the inner cylinder cavity is configured to divide the inner cylinder cavity into an independent upper air chamber and a lower air chamber, wherein the lower air chamber is constantly connected to the compressed gas inlet channel. The gap space formed by the outer cylinder around the impact piston includes an upper fluid space and a lower fluid space from top to bottom. An air outlet channel is provided in the drill bit body, and the lower fluid space is constantly connected to the air outlet channel.

[0007] In the initial state, the lower air chamber of the inner cylinder is disconnected from the upper fluid space, while the upper air chamber of the inner cylinder is connected to the upper fluid space, and the upper and lower fluid spaces remain connected. Due to the upward movement of the impact piston, the lower air chamber of the inner cylinder can connect with the upper fluid space, and the upper and lower fluid spaces are disconnected, thus forming a pressure chamber in the upper fluid space. Due to the downward movement of the impact piston, the lower air chamber of the inner cylinder can disconnect from the upper fluid space again, and the upper and lower fluid spaces reconnect.

[0008] Furthermore, the piston section of the impact piston located in the inner cylinder cavity is provided with an upper flange, which forms a circumferential contact fit with the inner wall of the inner cylinder to divide the inner cylinder cavity into an upper air chamber and a lower air chamber.

[0009] Furthermore, the impact piston is provided with a lower flange on the piston section in the outer cylinder. In the initial state, it is located in the lower fluid space and is configured such that the upward movement of the impact piston can form a circumferential contact with the inner wall of the outer cylinder in the upper fluid space, so as to form a pressure chamber in the upper fluid space.

[0010] Furthermore, it also includes a fluid communication path for forming a connection between the inner cylinder cavity and the upper fluid space; the fluid communication path includes a gap communication channel formed by the gap between the outer wall of the inner cylinder and the inner wall of the outer cylinder and a transition channel opened at the bottom of the inner cylinder, one end of the transition channel being connected to the gap communication channel and the other end being connected to the upper fluid space.

[0011] Furthermore, it also includes an upper connecting hole, which is disposed on the side wall of the inner cylinder and near the upper end of the inner cylinder; when the upper flange moves upward based on the impact piston and exceeds the lower edge of the upper connecting hole, the lower air chamber of the inner cylinder can be connected with the fluid communication path through the upper connecting hole.

[0012] Furthermore, it also includes a lower connecting hole, which is provided on the side wall of the inner cylinder and located near the lower end of the inner cylinder; the lower air chamber of the inner cylinder is kept in constant communication with the compressed gas inlet channel by means of the lower connecting hole.

[0013] Furthermore, the impact piston includes an upper piston body and a lower piston body. The lower piston body is located inside the outer cylinder, and the upper end of the upper piston body is located in the inner cylinder cavity. The upper piston body extends from top to bottom out of the inner cylinder and connects with the lower piston body. An upper flange is formed on the piston section of the upper piston body located in the inner cylinder cavity, and a lower flange is formed on the lower piston body.

[0014] Furthermore, a connecting channel is provided at the end of the lower piston body; in the initial state, the lower fluid space is connected to the air outlet channel through the connecting channel.

[0015] Furthermore, it also includes an air inlet connector, which is attached to the other end of the outer cylinder relative to the drill body; and an on / off valve for opening and closing between the compressed gas inlet passage and the air inlet of the air inlet connector.

[0016] Furthermore, the opening and closing valve is axially positioned and supported at the upper end of the inner cylinder, and the upper end of the inner cylinder forms a seal; the inner cylinder includes an inner cylinder body and a bushing that forms a seal on the lower part of the inner cylinder body, the upper piston body passes through the bushing, and a transition channel is formed on the bushing.

[0017] Beneficial effects: In the pneumatic down-the-hole hammer of the present invention, the air chamber in the inner cylinder is separated by the piston structure, while the fluid space in the outer cylinder is formed by the space surrounding the piston. This allows compressed air to alternately enter different air chambers to drive the piston to reciprocate without the need to open fluid channels on the piston wall and the outer cylinder wall. This not only reduces manufacturing costs and process difficulty based on the simple structure, but also greatly improves the strength of the piston to withstand loads, thereby significantly increasing the service life of the piston component and the overall down-the-hole hammer. Moreover, based on the unique fluid channel path of the present invention, the piston's impact terminal velocity and impact frequency are relatively high while ensuring normal piston operation.

[0018] The pneumatic down-the-hole hammer of the present invention is disclosed in detail below with reference to the embodiments shown in the accompanying drawings and the reference numerals. Attached Figure Description

[0019] Figure 1A schematic diagram of the overall structure of the pneumatic down-the-hole hammer of the present invention is shown.

[0020] Figure Labels

[0021] 1 Outer cylinder, 2 Inner cylinder, 3 Impact piston, 4 Drill body, 5 Upper air chamber of inner cylinder, 6 Lower air chamber of inner cylinder, 7 Upper fluid space, 8 Lower fluid space, 9 Exhaust passage, 10 Upper flange, 11 Lower flange, 12 Gap connecting passage, 13 Transition passage, 14 Upper connecting hole, 15 Lower connecting hole, 16 Connecting passage, 17 Inlet connector, 18 Inlet port, 19 Retaining ring and 20 Limiting bushing, 21 Exhaust fluid passage, 22 Spline sleeve, 23 Connector intake passage, 24 Valve seat, 25 Valve body, 26 Gap intake passage.

[0022] 201 Inner cylinder body, 202 Bushing, 301 Upper piston body, 302 Lower piston body. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0025] Figure 1 A schematic diagram of the overall structure of the pneumatic down-the-hole hammer of the present invention is shown. (Combined with...) Figure 1 As shown, the present invention discloses a pneumatic down-the-hole hammer, including an outer cylinder, an inner cylinder, an impact piston, and a drill bit body. The drill bit body is attached to the end of the outer cylinder. The inner cylinder is axially positioned inside the outer cylinder. The impact piston is located inside the outer cylinder, and the upper part of the impact piston is located in the inner cylinder cavity of the inner cylinder. The impact piston can be driven by air pressure difference to move axially relative to the outer cylinder and the inner cylinder.

[0026] In addition, the pneumatic down-the-hole hammer also includes a spline sleeve 22, a retaining ring 19, and a limiting bushing 20. The spline sleeve 22, retaining ring 19, and limiting bushing 20 can be coupled to the outer cylinder in an existing manner. For example, in one embodiment, the lower end of the outer cylinder is connected to the spline sleeve 22 by a thread, the spline on the drill body mates with the spline groove on the spline sleeve 22, the retaining ring 19 is locked in the annular groove on the upper part of the spline of the drill body and blocks the top surface of the spline sleeve 22 to prevent the drill body from falling out of the spline sleeve 22. In a preferred embodiment, the retaining ring 19 is a semi-circular lock. The limiting bushing 20 is sleeved on the upper outer periphery of the drill body, and the upper top surface of the limiting bushing 20 abuts against the lower end face of the radial inner flange of the second cylinder and the lower bottom surface presses against the retaining ring 19 to limit the retaining ring 19.

[0027] Additionally, it includes an air inlet connector, which is attached to the other end of the outer cylinder relative to the drill bit body; it also includes an on / off valve for opening and closing between the compressed gas inlet channel and the air inlet of the air inlet connector. In the specific structure, the air inlet connector has an air inlet, and the lower part of the air inlet connector is enlarged to form an air inlet channel 23. The valve seat 24 of the on / off valve is axially positioned and supported at the upper end of the inner cylinder body and forms a blockage at the upper end of the inner cylinder body. The valve body 25 of the on / off valve extends into the air inlet connector. The top surface of the valve body 25 has a closed state that is tightly engaged with the connection between the air inlet and the air inlet channel 23, and an open state that is disengaged from the connection between the air inlet and the air inlet channel 23, thereby realizing the opening and closing of the air inlet of the air inlet connector.

[0028] In a preferred embodiment of the present invention, the piston section of the impact piston located in the inner cylinder cavity is configured to divide the inner cylinder cavity into an independent upper inner cylinder air chamber and a lower inner cylinder air chamber, wherein the lower inner cylinder air chamber is in constant communication with the compressed gas inlet channel; the gap space formed by the outer cylinder around the impact piston includes an upper fluid space and a lower fluid space from top to bottom; an air outlet channel is provided in the drill bit body, and the lower fluid space is in constant communication with the air outlet channel.

[0029] In the initial state, the lower air chamber of the inner cylinder is disconnected from the upper fluid space, while the upper air chamber of the inner cylinder is connected to the upper fluid space, and the upper and lower fluid spaces remain connected. Due to the upward movement of the impact piston, the lower air chamber of the inner cylinder can connect with the upper fluid space, and the upper and lower fluid spaces are disconnected, thus forming a pressure chamber in the upper fluid space. Due to the downward movement of the impact piston, the lower air chamber of the inner cylinder can disconnect from the upper fluid space again, and the upper and lower fluid spaces reconnect.

[0030] The compressed gas inlet channel includes the aforementioned connector inlet channel 23 and gap inlet channel 26, wherein the gap inlet channel 26 is formed by a reserved gap between the side wall of the outer cylinder body and the inner wall of the outer cylinder.

[0031] That is, in the initial state, the high-pressure compressed gas can push the opening and closing valve to open, thereby entering the compressed gas inlet channel, and then entering the lower air chamber of the inner cylinder through the gap inlet channel 26. Since the lower air chamber of the inner cylinder is only connected to the gap inlet channel 26 in the initial state, when the compressed gas enters the lower air chamber of the inner cylinder, it will create pressure in the lower air chamber of the inner cylinder, thereby forcing the piston to move upward. When the piston moves upward and after the movement, the residual gas in the upper air chamber of the inner cylinder will enter the upper fluid space, then enter the lower fluid space, and finally enter the air outlet channel of the drill body.

[0032] When the impact piston moves upward to a certain stroke, specifically, when the impact piston moves upward to the point where the lower air chamber of the inner cylinder connects with the upper fluid space, the connection between the upper and lower fluid spaces is also broken due to the upward movement of the impact piston. This causes the high-pressure gas entering through the compressed gas inlet channel to enter the upper fluid space sequentially through the lower air chamber of the inner cylinder and the fluid connection path (mentioned below). At this time, because the connection between the upper and lower fluid spaces is cut off, the upper fluid space forms an independent air chamber relative to the lower fluid space, causing the high-pressure gas flowing into it to create pressure buildup, which in turn pushes the impact piston to produce an upward deceleration and downward acceleration motion, thus impacting the drill bit body.

[0033] When the impact piston moves downward to a certain stroke, specifically, when the impact piston moves downward to the point where the upper fluid space and the lower fluid space are reconnected, the compressed gas will re-enter the exhaust channel of the drill bit body through the lower fluid space, and blow away the drilling at the bottom of the hole through the exhaust fluid channel 21 at the bottom of the drill bit body, thereby achieving bottom hole slag removal.

[0034] When the impact piston moves downward to its original position, one reciprocating motion of the impact piston is completed.

[0035] By repeating the above process, impact drilling can be achieved based on the pneumatic down-the-hole hammer of this invention.

[0036] In a preferred embodiment, the piston section of the impact piston located in the inner cylinder cavity is provided with an upper flange, which forms a circumferential contact with the inner wall of the inner cylinder to divide the inner cylinder cavity into an upper air chamber and a lower air chamber. In this invention, the flange refers to a structure formed on the side wall of the piston in a radially outward manner along the circumferential direction. The outer diameter of the flange location is relatively larger than the outer diameter of the piston sections above and below the flange location. The lower flange, which will be mentioned below, also has this structure. Of course, those skilled in the art will fully understand that the outer diameters of the upper and lower flanges do not need to be the same.

[0037] In a preferred embodiment, the impact piston has a lower flange on the piston section located in the outer cylinder. Initially, the lower flange is positioned within the lower fluid space and is configured such that the upward movement of the impact piston allows it to form a circumferential contact with the inner wall of the outer cylinder in the upper fluid space, thereby creating a pressure chamber in the upper fluid space. Specifically, the lower flange is configured such that, during the upward movement of the impact piston, when the lower flange is drawn into the upper fluid space, it forms a tight circumferential contact with the inner wall of the outer cylinder in the upper fluid space, thus severing the connection between the upper and lower fluid spaces and allowing a pressure chamber to form in the upper fluid space.

[0038] It should be particularly noted that in this invention, the upper air chamber of the inner cylinder is a pressure-retaining air chamber used to push the impact piston upward, while when the connection between the upper fluid space and the lower fluid space is cut off, the upper fluid space forms a pressure-retaining air chamber used to push the impact piston downward. Furthermore, it should be particularly noted that in this invention, viewed from the axial direction of the outer cylinder, the upper air chamber of the inner cylinder is located above the upper fluid space, which is completely different from the structure in the prior art.

[0039] In addition, it should be noted that the terms "up" and "down" are relative to the drilling direction of the drill bit body. That is, a position facing or close to the drilling direction of the drill bit body can be designated as "down", while a position facing away from or far from the drilling direction of the drill bit body can be designated as "up".

[0040] In a preferred embodiment, a fluid communication path is further included for forming a connection between the inner cylinder cavity and the upper fluid space; the fluid communication path includes a gap communication channel formed by the gap between the outer wall of the inner cylinder and the inner wall of the outer cylinder and a transition channel opened at the bottom of the inner cylinder, one end of the transition channel being connected to the gap communication channel and the other end being connected to the upper fluid space.

[0041] This includes an upper connecting hole and a lower connecting hole. The upper connecting hole is located on the side wall of the inner cylinder, near the upper end of the inner cylinder. When the upper flange moves upward due to the impact piston and exceeds the lower edge of the upper connecting hole, the lower air chamber of the inner cylinder can be connected to the fluid communication path through the upper connecting hole. The lower connecting hole is located on the side wall of the inner cylinder, near the lower end of the inner cylinder. The lower air chamber of the inner cylinder is constantly connected to the compressed gas inlet channel through the lower connecting hole.

[0042] In a preferred embodiment, the impact piston includes an upper piston body and a lower piston body. The lower piston body is located inside the outer cylinder, and the upper end of the upper piston body is located in the inner cylinder cavity. The upper piston body extends from top to bottom out of the inner cylinder and connects with the lower piston body. An upper flange is formed on the piston section of the upper piston body located in the inner cylinder cavity, and a lower flange is formed on the lower piston body.

[0043] In a preferred embodiment, a connecting channel is provided at the end of the lower piston body; in the initial state, the lower fluid space is connected to the air outlet channel by means of the connecting channel.

[0044] In a preferred embodiment, the inner cylinder includes an inner cylinder body and a bushing that forms a seal on the lower part of the inner cylinder body, with the upper piston body passing through the bushing and a transition channel formed on the bushing.

[0045] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0046] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A pneumatic down-the-hole hammer, comprising an outer cylinder (1), an inner cylinder (2), an impact piston (3), and a drill body (4), the drill body (4) being attached to the end of the outer cylinder (1), the inner cylinder (2) being axially positioned inside the outer cylinder (1), the impact piston (3) being located inside the outer cylinder (1), and the upper part of the impact piston (3) being located in the inner cavity of the inner cylinder (2), the impact piston (3) being capable of being driven by means of a pressure difference to move axially relative to the outer cylinder (1) and the inner cylinder (2); characterized in that, The piston section of the impact piston (3) located in the inner cylinder cavity is configured to divide the inner cylinder cavity into an independent upper inner cylinder air chamber (5) and a lower inner cylinder air chamber (6), wherein the lower inner cylinder air chamber (6) is in constant communication with the compressed gas inlet channel; The gap space formed by the outer cylinder (1) around the impact piston (3) includes an upper fluid space (7) and a lower fluid space (8) from top to bottom; an air outlet channel (9) is provided inside the drill bit body (4), and the lower fluid space (8) is in constant communication with the air outlet channel (9); In the initial state, the lower air chamber (6) of the inner cylinder is disconnected from the upper fluid space (7), the upper air chamber (5) of the inner cylinder is connected to the upper fluid space (7), and the upper fluid space (7) and the lower fluid space (8) remain connected. Based on the upward movement of the impact piston (3), the lower cylinder chamber (6) can communicate with the upper fluid space (7), and the upper fluid space (7) is disconnected from the lower fluid space (8), thereby forming a pressure chamber in the upper fluid space (7); based on the downward movement of the impact piston (3), the lower cylinder chamber (6) can be disconnected from the upper fluid space (7) again, and the upper fluid space (7) and the lower fluid space (8) are reconnected. The impact piston (3) is provided with an upper flange (10) on the piston section in the inner cylinder cavity, which forms a circumferential contact with the inner wall of the inner cylinder (2) to divide the inner cylinder cavity into an upper air chamber (5) and a lower air chamber (6). The impact piston (3) is provided with a lower flange (11) on the piston section in the outer cylinder (1). In the initial state, it is located in the lower fluid space (8) and is configured such that the upward movement of the impact piston (3) can form a circumferential contact with the inner wall of the outer cylinder (1) of the upper fluid space (7) to form a pressure chamber in the upper fluid space (7). It also includes a fluid communication path for forming a connection between the inner cylinder cavity and the upper fluid space (7); The fluid communication path includes a gap communication channel (12) formed by the gap between the outer wall of the inner cylinder (2) and the inner wall of the outer cylinder (1) and a transition channel (13) opened at the bottom of the inner cylinder (2). One end of the transition channel (13) is connected to the gap communication channel (12), and the other end is connected to the upper fluid space (7).

2. The pneumatic down-the-hole hammer according to claim 1, characterized in that, It also includes an upper connecting hole (14), which is provided on the side wall of the inner cylinder (2) and is located near the upper end of the inner cylinder (2); When the upper flange (10) moves upward based on the impact piston (3) and exceeds the lower edge of the upper connecting hole (14), the lower cylinder chamber (6) can form a connection with the fluid communication path through the upper connecting hole (14).

3. The pneumatic down-the-hole hammer according to claim 2, characterized in that, It also includes a lower connecting hole (15), which is provided on the side wall of the inner cylinder (2) and near the lower end of the inner cylinder (2); The lower air chamber (6) of the inner cylinder is kept in constant communication with the compressed gas inlet channel by means of the lower connecting hole (15).

4. The pneumatic down-the-hole hammer according to claim 3, characterized in that, The impact piston (3) includes an upper piston body (301) and a lower piston body (302). The lower piston body (302) is located inside the outer cylinder (1). The upper end of the upper piston body (301) is located in the inner cylinder cavity. The upper piston body (301) extends from top to bottom out of the inner cylinder (2) and forms a connection with the lower piston body (302). The upper flange (10) is formed on the piston section of the upper piston body (301) located in the inner cylinder cavity, and the lower flange (11) is formed on the lower piston body (302).

5. The pneumatic down-the-hole hammer according to claim 4, characterized in that, A connecting channel (16) is provided at the end of the lower piston body (302). In the initial state, the lower fluid space (8) is connected to the air outlet channel (9) by means of the connecting channel (16).

6. The pneumatic down-the-hole hammer according to claim 1, characterized in that, It also includes an air inlet connector (17), which is attached to the other end of the outer cylinder (1) relative to the drill body (4); It also includes an on / off valve for creating an opening and closing between the compressed gas inlet passage and the inlet (18) of the inlet connector (17).

7. The pneumatic down-the-hole hammer according to claim 6, characterized in that, The opening and closing valve is axially positioned and supported at the upper end of the inner cylinder (2), and the upper end of the inner cylinder (2) forms a blockage; The inner cylinder (2) includes an inner cylinder body (201) and a bushing (202) that forms a seal on the lower part of the inner cylinder body (201). The upper piston body (301) passes through the bushing (202), and the transition channel (13) is formed on the bushing (202).

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