A hydraulic buffer structure with continuously adjustable buffer force and a hydraulic rock drill using it.

Abstract

This utility model discloses a continuously adjustable hydraulic buffer structure and a hydraulic rock drill using the same. During the advance and retraction of the drill bit, the first control chamber remains a high-pressure chamber, while the second control chamber becomes a low-pressure chamber when the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to a preset value. Furthermore, the return oil flow area of ​​the pressurized oil in the second control chamber continuously changes. This allows the buffer piston to constantly press against the drill bit during its forward movement and also increases the buffering range through the first control chamber during the drill bit's retraction, achieving stepless buffering and excellent transient response capability, thus preventing pressure fluctuations and piston oscillations. Moreover, when the buffer piston retracts until the distance between it and the rear wall of the second control chamber is less than the preset value, the second control chamber switches from a low-pressure chamber to a high-pressure chamber, preventing the buffer piston from impacting the rear wall of the second control chamber due to excessive buffering force.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic rock drill technology, and in particular, to a hydraulic buffer structure with continuously adjustable buffer force. In addition, it also relates to a hydraulic rock drill using the above-mentioned continuously adjustable hydraulic buffer structure. Background Technology

[0002] A hydraulic rock drill is an impact rotary drilling device that primarily utilizes a piston striking the drill bit to convert the piston's kinetic energy into stress wave energy, which is then transmitted to the rock interior via the drill rod to achieve rock breaking and drilling. Since both the drill bit and the rock have a certain degree of elasticity, a rebound inevitably occurs after the drill bit collides with the rock. If the rebounding drill bit directly impacts the internal parts of the rock drill, transferring energy to the machine body, it will not only affect energy utilization but, more seriously, damage the internal components, thus impacting the overall lifespan and operational reliability of the rock drill. Furthermore, during drilling, each impact of the drill bit causes a certain volume of rock to break, and the drill bit moves forward a certain distance. If the drill bit cannot quickly move forward and press against the rock wall, the energy generated by the next impact will not be transmitted to the rock interior, resulting in dry drilling and affecting the drilling speed and lifespan of the rock drill.

[0003] Therefore, existing technologies have designed hydraulic buffer structures with buffer pistons. These structures apply high-pressure hydraulic oil to the working surface of the buffer piston, ensuring the drill bit remains firmly pressed against the rock wall. This allows the energy generated by the hydraulic rock drill to be transferred to the rock interior to the maximum extent, achieving efficient and reliable drilling. For example, Chinese utility model patent application CN115075723A discloses a hydraulic rotary impact hammer drill with a stop piston. However, in this utility model patent application, the second control chamber is supplied with high-pressure fluid through a calibration orifice of fixed size, resulting in a fixed buffer force. This means the buffer force cannot be dynamically adjusted according to actual working conditions (such as rock hardness, impact frequency, and recoil amplitude). When facing complex and variable working conditions, the fixed buffer force may lead to insufficient or excessive recoil suppression. Under hard rock or high-frequency impact, the recoil force may exceed the preset buffer range, causing the stop piston to collide with the rear wall of the second control chamber. Under soft rock or low-frequency conditions, excessive buffering may reduce energy transfer efficiency. In addition, the flow restriction of the calibration orifice may lead to insufficient transient response. When the stop piston recoils violently or advances, the filling / draining speed of the fluid through the fixed orifice is limited, making it difficult to adjust the chamber pressure in time. This can easily cause pressure fluctuations and piston oscillations. Pressure fluctuations may disrupt the balance position of the stop piston, affecting the positioning accuracy of its shank and easily aggravating the wear of the drill rod and the cutter. Utility Model Content

[0004] This utility model provides a continuously adjustable hydraulic buffer structure and a hydraulic rock drill using it. It achieves stepless buffering, has excellent transient response capability, can avoid pressure fluctuations and piston oscillations, and can also prevent the buffer piston from hitting the rear wall of the second control chamber due to excessive buffering force.

[0005] According to one aspect of this utility model, a continuously adjustable hydraulic buffer structure is provided, suitable for a hydraulic rock drill. It includes an impact piston and a buffer piston, which are slidably mounted in the piston cylinder of the rock drill body along the impact axis. The impact piston is sleeved on the buffer piston. The impact piston is used to impact the drill bit, and the buffer piston is used to hold the drill bit. A first control chamber and a second control chamber are formed between the buffer piston and the piston cylinder. The first control chamber remains connected to a high-pressure oil supply line during the forward and backward movement of the buffer piston. When the distance between the buffer piston and the rear wall of the second control chamber is less than a preset value, high-pressure oil is introduced into the second control chamber. When the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to the preset value, the second control chamber is connected to a low-pressure return oil line, and the return oil flow area continuously changes during the return oil process.

[0006] Furthermore, the buffer piston is provided with a first connecting channel, which communicates with the second control chamber. The piston cylinder is provided with a first annular channel, which is always connected to the low-pressure return oil pipeline. When the distance between the buffer piston and the rear wall of the second control chamber is less than a preset value, the first connecting channel and the first annular channel are not connected. When the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to the preset value, the first connecting channel and the first annular channel are connected. During the movement of the buffer piston, the flow area between the first connecting channel and the first annular channel changes continuously.

[0007] Furthermore, the first annular channel is an annular groove structure, including an annular groove and a return oil channel. The annular groove is connected to the annular chamber through the return oil channel. The annular groove is used to communicate with the first connecting channel. The annular chamber is always connected to the low-pressure return oil pipeline.

[0008] Furthermore, the buffer piston is provided with a second connecting channel, which communicates with the second control chamber. The piston cylinder is provided with a second annular channel, which is connected to a high-pressure oil source. When the distance between the buffer piston and the rear wall of the second control chamber is less than a preset value, the second connecting channel communicates with the second annular channel. When the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to the preset value, the second connecting channel does not communicate with the second annular channel.

[0009] Furthermore, the second annular channel is connected to the buffer high-pressure oil supply pipeline.

[0010] Furthermore, a third control chamber is formed between the buffer piston and the piston cylinder. A third connecting channel is provided on the buffer piston. When the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to a preset value, the third connecting channel connects the third control chamber and the first control chamber. When the distance between the buffer piston and the rear wall of the second control chamber is less than the preset value, the third connecting channel does not connect the third control chamber and the first control chamber.

[0011] Furthermore, a main control chamber is formed between the impact piston and the piston cylinder. The main control chamber is always connected to the high-pressure oil supply line. A piston boss is provided on the outer wall of the portion of the impact piston located in the main control chamber. The front part of the main control chamber is provided with a concave cavity that cooperates with the piston boss.

[0012] Furthermore, a secondary control chamber is formed between the impact piston and the piston cylinder. The secondary control chamber is connected to a distributor, which is connected to a high-pressure oil supply line and a low-pressure oil return line. During the advancement of the impact piston, the distributor is connected to the high-pressure oil supply line, and during the retraction of the impact piston, the distributor is connected to the low-pressure oil return line.

[0013] Furthermore, a backstop bushing is provided between the buffer piston and the drill bit.

[0014] In addition, this utility model also provides a hydraulic rock drill, which adopts the hydraulic buffer structure with continuously adjustable buffer force as described above.

[0015] This utility model has the following beneficial effects:

[0016] This invention relates to a continuously adjustable hydraulic buffer structure. During the advance and retraction of the drill bit, high-pressure oil is always supplied to the first control chamber, which is never connected to the low-pressure return oil line, meaning the first control chamber is always a high-pressure chamber. The second control chamber is connected to the low-pressure return oil line after the distance between the buffer piston and the rear wall of the second control chamber is greater than or equal to a preset value, meaning the second control chamber is a low-pressure chamber. The return oil flow area of ​​the pressure oil in the second control chamber continuously changes. This allows the first control chamber to provide a continuously adjustable steady-state propulsion force during the advance of the drill bit, ensuring that the buffer piston always presses against the drill bit. During the retraction of the drill bit, the buffer range is increased through the first control chamber, and stepless buffering is achieved through the continuous change of the return oil flow area of ​​the pressure oil in the second control chamber. It also has excellent transient response capability, preventing pressure fluctuations and piston oscillations. Furthermore, after the buffer piston retracts to a distance less than a preset value between itself and the rear wall of the second control chamber, high-pressure oil will be introduced into the second control chamber, and it will no longer be connected to the low-pressure return oil line. This allows the second control chamber to switch from the low-pressure chamber to the high-pressure chamber, which can prevent the buffer piston from hitting the rear wall of the second control chamber due to excessive buffering force.

[0017] In addition, the hydraulic rock drill of this invention also has the above-mentioned advantages.

[0018] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the figures. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of a hydraulic buffer structure with continuously adjustable buffer force according to a preferred embodiment of this application.

[0021] Explanation of reference numerals in the attached figures

[0022] 1. Impact piston; 2. Buffer piston; 3. First control chamber; 4. Second control chamber; 5. High-pressure oil supply line; 6. Low-pressure oil return line; 7. Buffer high-pressure oil supply line; 8. Third control chamber; 9. Main control chamber; 10. Secondary control chamber; 11. Distributor; 12. Anti-reverse bushing; 13. High-pressure accumulator; 14. Low-pressure accumulator; 21. First connecting channel; 22. Second connecting channel; 23. Third connecting channel; 91. Cavity; 101. Piston boss; 201. First annular channel; 202. Second annular channel; 2011. Annular groove; 2012. Annular chamber; 2013. Oil return channel; 100. Rock drill body; 200. Piston cylinder; 300. Drill tail. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] Reference Figure 1 A preferred embodiment of this application provides a hydraulic buffer structure with continuously adjustable buffer force, suitable for hydraulic rock drills. It includes an impact piston 1 and a buffer piston 2, which are slidably mounted along the impact axis within the piston cylinder 200 of the rock drill body 100. The impact piston 1 is sleeved on the buffer piston 2. The impact piston 1 is used to impact the drill bit 300, and the buffer piston 2 is used to abut against the drill bit 300. A first control chamber 3 and a second control chamber 4 are formed between the buffer piston 2 and the piston cylinder 200. The first control chamber 3 remains connected to the high-pressure oil supply line 5 during the forward and backward movement of the buffer piston 2. When the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is less than a preset value, high-pressure oil is introduced into the second control chamber 4. When the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is greater than or equal to the preset value, the second control chamber 4 is connected to the low-pressure return oil line 6, and the return oil flow area continuously changes during the return oil process.

[0025] It can be understood that the operation process of the continuously adjustable hydraulic buffer structure in this embodiment is as follows: Under normal working conditions, that is, when the drill bit 300 is in the preset equilibrium position, when the impact piston 1 moves along axis A towards the drill bit 300 under the action of high pressure oil and impacts the drill bit 300, at the same time, high pressure oil enters the first control chamber 3. After the drill bit 300 moves forward, the buffer piston 2 moves forward in time under the action of high pressure oil in the first control chamber 3 to block the drill bit 300, so as to absorb the energy rebounded by the drill bit 300 in time and avoid the impact of the rebound energy of the drill bit 300 on the internal parts. At the same time, the buffer piston 2 can provide a stable thrust, so that the drill bit blocks the rock, which is beneficial to improving the energy transmission efficiency and the life of the hydraulic rock drill. When the drill bit 300 rebounds after impacting the rock surface, the buffer piston 2 moves backward under the push of the drill bit 300 to decelerate it. During the backward movement, the buffer piston 2 forces the pre-charged pressurized oil in the second control chamber 4 into the low-pressure return oil line 6 to achieve oil return in the second control chamber 4. Furthermore, during the return of pressurized oil in the second control chamber 4, the return oil flow area continuously changes, thus achieving stepless buffering of the buffer piston 2. Additionally, when the buffer piston 2 retracts to a distance less than a preset value between itself and the rear wall of the second control chamber 4, high-pressure oil flows into the second control chamber 4 and it is no longer connected to the low-pressure return oil line 6, switching the second control chamber 4 from a low-pressure chamber to a high-pressure chamber. This prevents the buffer piston 2 from impacting the rear wall of the second control chamber 4.

[0026] It is understood that in the continuously adjustable hydraulic buffer structure of this utility model, during the forward and backward movement of the drill bit 300, high-pressure oil is always supplied to the first control chamber 3, and the first control chamber 3 is never connected to the low-pressure return oil line 6, that is, the first control chamber 3 is always a high-pressure chamber. Meanwhile, the second control chamber 4 is connected to the low-pressure return oil line 6 after the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is greater than or equal to a preset value, that is, the second control chamber 4 is a low-pressure chamber at this time, and the return oil flow area of ​​the pressure oil in the second control chamber 4 continuously changes. This allows for a continuously variable and steady-state propulsion force to be provided by the first control chamber 3 during the forward movement of the drill bit 300, ensuring that the buffer piston 2 is always against the drill bit 300. Furthermore, during the backward movement of the drill bit 300, the high-pressure oil in the first control chamber 3 enhances the buffering range and provides continuous braking. The continuously changing return flow area of ​​the pressure oil in the second control chamber 4 ensures smooth and continuous pressure variation, achieving stepless buffering and excellent transient response capabilities, thus preventing pressure fluctuations and piston oscillations. Moreover, when the buffer piston 2 retracts to a distance less than a preset value between itself and the rear wall of the second control chamber 4, high-pressure oil is introduced into the second control chamber 4, and it is no longer connected to the low-pressure return oil line 6. This switches the second control chamber 4 from a low-pressure chamber to a high-pressure chamber, preventing the buffer piston 2 from impacting the rear wall of the second control chamber 4 due to excessive buffering force.

[0027] The buffer piston 2 has a first connecting channel 21 that communicates with the second control chamber 4. The piston cylinder 200 has a first annular channel 201 that is always connected to the low-pressure return oil pipeline 6. When the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is less than a preset value, the first connecting channel 21 and the first annular channel 201 are not connected, meaning that the pressure oil in the second control chamber 4 will not return through the low-pressure return oil pipeline 6. When the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is greater than or equal to the preset value, the first connecting channel 21 and the first annular channel 201 remain connected, allowing the pressure oil in the second control chamber 4 to return through the low-pressure return oil pipeline 6. During the movement of the buffer piston 2, the flow area between the first connecting channel 21 and the first annular channel 201 changes continuously, thereby making the pressure in the second control chamber 4 change smoothly and continuously, thus achieving stepless buffering. For example, the cross-sectional shape of the first connecting channel 21 is circular or elliptical, and the cross-sectional shape of the first annular channel 201 is also circular or elliptical. During the process of the buffer piston 2 moving from front to back, the cross-section of the first connecting channel 21 is initially contained within the cross-section of the first annular channel 201, at which point the flow area is at its maximum, which is the cross-sectional area of ​​the first connecting channel 21. Then, as the buffer piston 2 continues to move backward, the two gradually intersect, and the flow area becomes the intersection area of ​​the two cross-sectional shapes. Finally, as the buffer piston 2 continues to move backward, the two cross-sections separate, and the flow area becomes zero. When the buffer piston 2 moves from back to front, the two cross-sections separate and intersect sequentially until the cross-section of the first connecting channel 21 is contained within the cross-section of the first annular channel 201.

[0028] Optionally, the first annular channel 201 is an annular groove structure, including an annular groove 2011 and a return oil channel 2013. The annular groove 2011 is connected to the annular chamber 2012 through the return oil channel 2013. The annular groove 2011 is used to communicate with the first connecting channel 21. The annular chamber 2012 is always connected to the low-pressure return oil pipeline 6. The annular chamber 2012 is located on the piston cylinder 200. It can be understood that by adopting an annular structure design, it is beneficial to offset the peak value of high-frequency impact pressure, thereby reducing the risk of stress concentration at the drill bit 300.

[0029] In addition, the buffer piston 2 is provided with a second connecting channel 22, which is connected to the second control chamber 4. The piston cylinder 200 is provided with a second annular channel 202, which is connected to a high-pressure oil source. When the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is less than a preset value, the second connecting channel 22 is connected to the second annular channel 202, so that high-pressure oil is injected into the second control chamber 4. Since the second control chamber 4 is no longer connected to the low-pressure return oil line 6 at this time, the second control chamber 4 switches from the low-pressure chamber to the high-pressure chamber, which can prevent the buffer piston 2 from hitting the rear wall of the second control chamber 4, thereby effectively protecting the safety of the internal parts of the rock drill and improving its service life. After the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is greater than or equal to a preset value, the second connecting channel 22 and the second annular channel 202 are no longer connected, that is, high-pressure oil is no longer injected into the second control chamber 4. At this time, the second control chamber 4 is connected to the low-pressure return oil pipeline 6, and the pressure oil in the second control chamber 4 returns through the low-pressure return oil pipeline 6, thus switching the second control chamber 4 from the high-pressure chamber back to the low-pressure chamber. Optionally, the second annular channel 202 is connected to the buffer high-pressure oil supply pipeline 7, providing high-pressure oil to the second control chamber 4 through a separate buffer high-pressure oil source. Of course, in other embodiments of this utility model, the second annular channel 202 can also be connected to the high-pressure oil supply pipeline 5.

[0030] In addition, a third control chamber 8 is formed between the buffer piston 2 and the piston cylinder 200. A third connecting channel 23 is provided on the buffer piston 2. After the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is greater than or equal to a preset value, the third connecting channel 23 connects the third control chamber 8 and the first control chamber 3. During the forward movement of the buffer piston 2, the high-pressure oil in the first control chamber 3 is continuously injected into the third control chamber 8 through the third connecting channel 23. Since the third control chamber 8 is a blind chamber, the buffer piston 2 will continuously squeeze the pressure oil in the third control chamber 8 during the forward movement, so that the buffer piston 2 can decelerate and brake during the forward movement, preventing the buffer piston 2 from hitting the wall of the piston cylinder 200 during the forward movement. During the retraction of the buffer piston 2, the buffer piston 2 will continuously squeeze the pressure oil in the third control chamber 8 into the first control chamber 3 through the third connecting channel 23, which is beneficial to improve the buffer range. After the distance between the buffer piston 2 and the rear wall of the second control chamber 4 is less than a preset value, the third connecting channel 23 will not connect the third control chamber 8 and the first control chamber 3.

[0031] In addition, a main control chamber 9 and a secondary control chamber 10 are formed between the impact piston 1 and the piston cylinder 200. The main control chamber 9 is always connected to the high-pressure oil supply line 5, and the secondary control chamber 10 is connected to the distributor 11. The distributor 11 is connected to the high-pressure oil supply line 5 and the low-pressure oil return line 6. During the advancement of the impact piston 1, the distributor 11 is connected to the high-pressure oil supply line 5, and high-pressure oil is injected into the main control chamber 9 and the secondary control chamber 10 to push the impact piston 1 forward and impact the drill bit 300. During the retraction of the impact piston 1, the distributor 11 is connected to the low-pressure oil return line 6, so that the pressure oil in the secondary control chamber 10 is returned, while the pressure oil in the main control chamber 9 is squeezed back to the high-pressure oil supply line 5.

[0032] Optionally, the impact piston 1 is provided with a piston boss 101 on the outer wall of the portion of the main control chamber 9. The front part of the main control chamber 9 is provided with a concave cavity 91 that cooperates with the piston boss 101. When the drill bit 300 is stuck by a rock and cannot rebound backward, the drill bit 300 is in front of the preset equilibrium position. At this time, the displacement of the impact piston 1 increases, and the piston boss 101 enters the concave cavity 91. The piston boss 101 will squeeze the pressure oil in the concave cavity 91. Since the oil is incompressible, the impact piston 1 is decelerated and braked under the action of the pressure oil in the concave cavity 91, which can prevent the impact piston 1 from hitting the middle cylinder of the piston cylinder 200.

[0033] In addition, a backstop bushing 12 is provided between the buffer piston 2 and the drill bit 300. During the forward and backward movement, the buffer piston 2 abuts against the backstop bushing 12, and the backstop bushing 12 abuts against the drill bit 300.

[0034] In addition, a high-pressure accumulator 13 is installed on the high-pressure oil supply line 5, and a low-pressure accumulator 14 is installed on the low-pressure oil return line 6. When the buffer piston 2 retracts to buffer, the pressurized oil in the high-pressure oil supply line 5 is forced into the high-pressure accumulator 13 for energy storage, and the pressurized oil in the low-pressure oil return line 6 is forced into the low-pressure accumulator 14 for energy storage. The high-pressure accumulator 13 absorbs oil (stores energy) when the pressure peak is too high and releases oil (releases energy) when the pressure decreases, thus playing a role in peak shaving and pressure stabilization, absorbing shocks, and supplementing flow. The low-pressure accumulator 14 releases oil (releases energy) when the pressure in the return line decreases and absorbs oil (stores energy) when the pressure recovers to above the set value, thus playing a role in maintaining minimum pressure, preventing cavitation, and supplementing flow.

[0035] In addition, another embodiment of this utility model provides a hydraulic rock drill, which preferably adopts the hydraulic buffer structure with continuously adjustable buffer force as described above.

[0036] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0037] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0038] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A hydraulic buffer structure with continuously adjustable buffer force, suitable for hydraulic rock drills, characterized in that, The system includes an impact piston (1) and a buffer piston (2), which are slidably mounted in the piston cylinder (200) of the rock drill body (100) along the impact axis. The impact piston (1) is sleeved on the buffer piston (2). The impact piston (1) is used to impact the drill bit (300), and the buffer piston (2) is used to hold the drill bit (300) in place. A first control chamber (3) and a second control chamber (4) are formed between the buffer piston (2) and the piston cylinder (200). The first control chamber (3) remains connected to the high-pressure oil supply line (5) during the forward and backward movement of the buffer piston (2). After the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is less than a preset value, high-pressure oil is introduced into the second control chamber (4). After the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is greater than or equal to the preset value, the second control chamber (4) is connected to the low-pressure return oil line (6) and the return oil flow area changes continuously during the return oil process.

2. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 1, characterized in that, The buffer piston (2) is provided with a first connecting channel (21), which is connected to the second control chamber (4). The piston cylinder (200) is provided with a first annular channel (201), which is always connected to the low-pressure return oil pipeline (6). When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is less than a preset value, the first connecting channel (21) and the first annular channel (201) are not connected. When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is greater than or equal to the preset value, the first connecting channel (21) and the first annular channel (201) are connected. During the movement of the buffer piston (2), the flow area between the first connecting channel (21) and the first annular channel (201) changes continuously.

3. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 2, characterized in that, The first annular channel (201) is an annular groove structure, including an annular groove (2011) and a return oil channel (2013). The annular groove (2011) is connected to the annular chamber (2012) through the return oil channel (2013). The annular groove (2011) is used to communicate with the first connecting channel (21). The annular chamber (2012) is always connected to the low-pressure return oil pipeline (6).

4. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 1, characterized in that, The buffer piston (2) is provided with a second connecting channel (22), which is connected to the second control chamber (4). The piston cylinder (200) is provided with a second annular channel (202), which is connected to a high-pressure oil source. When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is less than a preset value, the second connecting channel (22) is connected to the second annular channel (202). When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is greater than or equal to the preset value, the second connecting channel (22) is not connected to the second annular channel (202).

5. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 4, characterized in that, The second annular channel (202) is connected to the buffer high-pressure oil supply pipeline (7).

6. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 1, characterized in that, A third control chamber (8) is formed between the buffer piston (2) and the piston cylinder (200). A third connecting channel (23) is provided on the buffer piston (2). When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is greater than or equal to a preset value, the third connecting channel (23) connects the third control chamber (8) and the first control chamber (3). When the distance between the buffer piston (2) and the rear wall of the second control chamber (4) is less than the preset value, the third connecting channel (23) does not connect the third control chamber (8) and the first control chamber (3).

7. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 1, characterized in that, A main control chamber (9) is formed between the impact piston (1) and the piston cylinder (200). The main control chamber (9) is always connected to the high-pressure oil supply line (5). A piston boss (101) is provided on the outer wall of the part of the impact piston (1) located in the main control chamber (9). The front part of the main control chamber (9) is provided as a concave cavity (91) that cooperates with the piston boss (101).

8. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 7, characterized in that, A secondary control chamber (10) is also formed between the impact piston (1) and the piston cylinder (200). The secondary control chamber (10) is connected to the distributor (11). The distributor (11) is connected to the high-pressure oil supply line (5) and the low-pressure oil return line (6). During the advancement of the impact piston (1), the distributor (11) is connected to the high-pressure oil supply line (5). During the retraction of the impact piston (1), the distributor (11) is connected to the low-pressure oil return line (6).

9. The hydraulic buffer structure with continuously adjustable buffer force as described in claim 1, characterized in that, A backstop bushing (12) is provided between the buffer piston (2) and the drill bit (300).

10. A hydraulic rock drill, characterized in that, The system employs a hydraulic buffer structure with continuously adjustable buffer force as described in any one of claims 1 to 9.

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