Pneumatic impact tool with vibration-damping structure

Abstract

The invention relates to a pneumatic impact tool with a vibration-damping structure, comprising a handle (1) in which a cylindrical element (2) and a changeover valve (22) are arranged. The cylindrical element (2) is connected to an inner tube (3) having an annular wall (31) and a cavity (32). A hammer body (4) is arranged in the cavity (32), dividing the cavity (32) into a front chamber (321) and a rear chamber (322). The annular wall (31) is provided with at least one air outlet hole (36), and compressed air is introduced into the front or rear chamber (321, 322) through the changeover valve (22). A channel is formed on the outer circumferential surface (43) of the hammer body, which is connected to the front chamber (321) but not to the rear chamber (322).When compressed air is introduced into the front chamber (321) through the first air inlet opening (34), the compressed air pushes the hammer body backwards, with the compressed air being released through the channel and the air outlet hole (36), thus reducing the pressure force on the hammer body (4).

Description

Technical field

[0001] The invention relates to a hand tool, in particular a pneumatic impact tool with a vibration-damping structure. State of the art

[0002] The pneumatic striking tool generates vibrations during use due to the reciprocating motion of the hammer body. Prolonged use can have detrimental effects on the user's hand. The greater the impact force of the pneumatic striking tool, the greater the vibration and the greater the potential damage to the user.

[0003] Taiwanese patent publications TW I235700 B and TW I729809 B each disclose a pneumatic tool. In this tool, an air chamber is formed behind the barrel. The air in the air chamber is compressed when the hammer body moves backward, thereby creating a damping effect and reducing the vibration caused by the hammer body on the barrel.Fig. Figure 4 of TW I729809 B shows another pneumatic tool. This tool incorporates a spring or rubber block behind the barrel. The spring or rubber block is compressed as the hammer body moves backward. This deformation creates a damping effect and reduces the vibration transmitted from the hammer body to the barrel.

[0004] The two conventional designs described above both add other components (the spatial configuration is modified to form an air chamber; a spring or rubber block is added, etc.) to the existing structure of the pneumatic tool. After the pneumatic tool has generated a significant vibration, this vibration is dampened. Besides the disadvantages of an increased number of components and higher costs, the damping effect is particularly poor.

[0005] In Fig. 5 of TW I235700 B features an air inlet tube connected to the front end of the barrel. This tube uses compressed air to propel the hammer body, which has already reached the front of the barrel, back. An air outlet hole is provided approximately in the middle of the barrel for pressure relief. During the process of the hammer body striking the tool head forward and then retracting, the compressed air in the barrel can only be released after the hammer body has passed the air outlet hole in the middle of the barrel. Before the compressed air is released, the hammer body has already been propelled back to the rear of the barrel by the compressed air, so it still strikes the rear end of the barrel with considerable force. This is the primary cause of vibration in pneumatic impact tools.

[0006] A pneumatic impact tool with the features of the preamble of claim 1 is known from US patent 6,192,997 B1. Further impact tools are described in patent applications DE 32 38 295 A1, DE 12 77 770 A and WO 2021 / 245 065 A1. Content of the invention

[0007] The object of the invention is to provide a pneumatic impact tool with a vibration-damping structure without adding additional components.

[0008] This problem is solved by the pneumatic impact tool with vibration-damping structure according to the invention, which has the features of claim 1. A further embodiment of the impact tool according to the invention is the subject of the dependent claim.

[0009] The striking tool is designed with a handle having a recess and an air inlet channel connected to the recess, with a switch provided in the air inlet channel; a cylindrical element arranged in the recess, wherein a switching valve is provided in the cylindrical element, wherein a through-hole connected to the air inlet channel is formed on the side wall of the cylindrical element, through which the compressed air is introduced into the switching valve; an inner tube having an annular wall and a cavity surrounded by the annular wall, wherein a hammer body is arranged in the cavity, which rests closely against the annular wall, thereby dividing the cavity into a front chamber and a rear chamber, wherein a tool head can be attached to the front end of the inner tube, wherein the annular wall is provided with at least one air outlet hole through which the cavity is connected to the outside air, wherein a long channel is formed in the annular wall connecting the changeover valve and the front chamber, wherein the long channel forms a first air inlet opening at the front chamber and a second air inlet opening at the rear chamber, which is connected to the changeover valve, and wherein the compressed air can be introduced into the front chamber through the first air inlet opening or into the rear chamber through the second air inlet opening; and the hammer body having a head near the first air inlet opening and an end near the second air inlet opening, wherein a channel is formed on the outer circumferential surface of the hammer body, the channel extending to the head and communicating with the front chamber, the channel not extending to the end so that the channel does not communicate with the rear chamber, wherein when compressed air is introduced into the rear chamber through the second air inlet opening, the compressed air pushes the hammer body, which is thus moved forward towards the tool head, and when compressed air is introduced into the front chamber through the first air inlet opening, the compressed air moves the hammer body backward away from the tool head, and wherein when the channel communicates with the air outlet hole, the compressed air in the front chamber is discharged through the channel and the air outlet hole.so that the pressure force on the hammer body is reduced.

[0010] The channel is formed by a spiral groove on the outer circumferential surface of the hammer body.

[0011] Furthermore, the ring wall is provided with three air outlet holes, the distances between the air outlet holes and the tool head varying. When the hammer body moves into the position where it contacts the tool head, the groove is connected to the two air outlet holes closest to the tool head.

[0012] Preferably, the distances between the air outlet holes and the tool head are no greater than half the total length of the cavity. Brief description of the drawings Fig. Figure 1 shows an exploded view of the first embodiment of the invention, Fig. 2 shows a sectional view of the first embodiment of the invention, Fig. Figure 3 shows a perspective view of the hammer body of the first embodiment of the invention, Fig. 4 to Fig. Figure 6 shows representations of the movement of the first embodiment of the invention, Fig. Figure 7 shows an exploded view of a second embodiment not belonging to the invention. Fig. Figure 8 shows a sectional view of the second embodiment not belonging to the invention. Fig. Figure 9 shows a perspective view of the hammer body of the second embodiment not belonging to the invention, Fig. 10 to Fig. Figure 12 shows representations of the movement of the second embodiment not belonging to the invention. Detailed description of preferred embodiments

[0013] Fig. 1 and Fig. Figure 2 shows the first embodiment of the present invention, comprising a handle 1, a cylindrical element 2, an inner tube 3, and a hammer body 4. The handle 1 can be pistol-shaped or straight. The handle 1 of this embodiment has a pistol shape. The handle 1 has a recess 11 at its top. An air inlet channel 12 extends upward from the underside of the handle 1, connected to the recess 11, and serves to connect to an external compressed air source. A switch 13 for controlling the airflow is provided in the air inlet channel 12. A button 14 on one side of the handle 1 is connected to the switch 13 for actuation.

[0014] The cylindrical element 2 of this embodiment is arranged in recess 11. The bottom of the recess 11 is provided with a spring 15 for damping the cylindrical element 2. A through-hole 21, connected to the air inlet channel 12, is formed in the side wall of the cylindrical element 2. A conventional changeover valve 22 is provided in the cylindrical element 2. After the compressed air is introduced into the air inlet channel 12, it enters the changeover valve 22 through the through-hole 21. The changeover valve 22 is used to discharge the compressed air in two different directions.

[0015] The inner tube 3 is a round tube with an annular wall 31 and a cavity 32 surrounded by the annular wall 31. The annular wall 31 extends into the cylindrical element 2 and is threaded to the cylindrical element 2. A hammer body 4 is arranged in the cavity 32, resting closely against the annular wall 31, thus further dividing the cavity 32 into a front chamber 321 and a rear chamber 322. The inner tube 3 projects from the cylindrical element 2. A tool head 5 can be attached to its front end. The tool head 5 can be replaced according to actual usage requirements. A long channel 33 is formed in the annular wall 31 outside the cavity 32 and is connected to the changeover valve 22. The long channel forms a first air inlet opening 34 at the front chamber 321 and a second air inlet opening 35 at the rear chamber 322, which is connected to the switching valve 22.Accordingly, the switching valve 22 can selectively release the compressed air to the long channel 33 at a suitable time, thereby introducing the compressed air into the front chamber 321 through the first air inlet opening 34. Or the compressed air is introduced into the rear chamber 322 through the second air inlet opening 35.

[0016] Furthermore, the annular wall 31 is provided with at least one air outlet hole 36 for connecting the cavity 32 to the outside air. In this embodiment, there are three air outlet holes 36. They are arranged in a straight line along the axial direction of the inner tube 3. The distances between the air outlet holes 36 and the tool head 5 are different. The three air outlet holes 36 mentioned above are also arranged between the first air inlet opening 34 and the second air inlet opening 35. The distances between the air outlet holes 36 and the tool head 5 are no greater than half the total length of the cavity 32.

[0017] As in Fig. 2 and Fig. As shown in Figure 3, the hammer body 4 has a head 41 near the first air inlet opening 34 and an end 42 near the second air inlet opening 35. Between them is an outer circumferential surface 43. The outer diameter of the hammer body 4 is equal to the inner diameter of the cavity 32, so that the outer circumferential surface 43 is in close contact with the annular wall 31. A channel is formed on the outer circumferential surface 43. The channel extends to the head 41 and communicates with the front chamber 321. However, the channel does not extend to the end 42, so that it does not communicate with the rear chamber 322. In this embodiment, the channel is formed by a groove 44 on the outer circumferential surface 43. The groove 44 is spiral in shape. The number and spacing of the grooves 44 can be customized as needed.

[0018] In this embodiment, the relative positional relationship between the groove 44 and the air outlet holes 36 is as shown in Fig. 4 shown. When the hammer body 4 moves into the position where it touches the tool head 5, the groove 44 is connected to two air outlet holes 36 that are closest to the tool head 5.

[0019] When button 14 is pressed to control switch 13, compressed air is introduced into the changeover valve 22 through air inlet channel 12. The changeover valve 22 first allows compressed air into the rear chamber 322 through the second air inlet opening 35. This forces the hammer body 4 forward at high speed, striking the tool head 5 to produce a working action. Subsequently, the changeover valve 22 reverses the air supply path and stops the entry of compressed air into the rear chamber 322 through the second air inlet opening 35. Instead, the compressed air is introduced into the long channel 33 and then into the front chamber 321 through the first air inlet opening 34. The technology for switching the air supply path of the changeover valve 22 is a well-known technology and will therefore not be repeated here.

[0020] This causes the hammer body 4 to be moved backwards by the compressed air. As in Fig. As shown in Figure 4, when the hammer body 4 begins to leave the tool head 5, the compressed air can be released to the outside through the groove 44 and the interconnected air outlet holes 36, thereby reducing the pressure in the front chamber 321 and thus weakening the pressing force on the hammer body 4. Accordingly, when the hammer body 4 reaches the endpoint of the Fig. The amplitude of the resulting vibration is reduced by the path shown in step 6.

[0021] During the vibration damping process of the present invention, when the hammer body 4 is at the starting point of the path, as in Fig. As shown in Figure 4, the compressed air can already be released through the groove 44 and the interconnected air outlet holes 36. In other words, the point of air release in the present invention is much earlier than in the conventional structure. Therefore, the compressive force on the hammer body 4 can be significantly reduced.

[0022] Furthermore, the compressed air can be used during the backward movement of the hammer body 4, as in Fig. As shown in Figure 5, the air is released through the groove 44 and various air outlet holes 36. This continuously reduces the pressure force on the hammer body 4, thus greatly reducing vibration.

[0023] The feature of the present invention is that the impact force of the backward-moving hammer body 4 of the pneumatic tool, which generates the vibration, is directly attenuated at the beginning of the vibration by the air release. This can produce a better vibration damping effect than the conventional structure. At the same time, it does not affect the force of the compressed air that moves the hammer body forward to strike the tool head. Therefore, the vibration reduction effect can be achieved provided that the output power of the pneumatic tool is taken into account.

[0024] Fig. Figures 7 to 9 show a second embodiment not belonging to the present invention, which is a pneumatic striking tool with the same construction as the previous embodiment. The difference lies in the structure of the hammer body 9. Therefore, the following description refers to the structure of the preceding embodiment.

[0025] The hammer body 9 also has a head 91 and an end 92 as in the previous embodiment. Between them is an outer circumferential surface 93. A channel is formed on the outer circumferential surface 93. The channel extends to the head 91 and is connected to the front chamber 321 as in the previous embodiment. However, the channel does not extend to the end 92, so that the channel is not connected to the rear chamber 322. In this embodiment, the channel has a groove 95 and a cylindrical gap 96. The groove 95 extends linearly along the direction of movement of the hammer body 9. One end of the groove is connected to the head 91 and thus to the front chamber 321. The other end is connected to the cylindrical gap 96. The cylindrical gap 96 is a space on the outer circumferential surface between a band-shaped depression 97 and the annular wall 31.

[0026] As in Fig. As shown in Figure 10, when the hammer body 9 moves into the position where it touches the tool head 5, the cylindrical gap 96 is connected to two air outlet holes 36 that are closest to the tool head 5.

[0027] As in the first embodiment, when the hammer body 9 is at the starting point of the Fig. As shown in section 10, the compressed air is released through the cylindrical gap 96 and the interconnected air outlet holes 36. In other words, the air release occurs much earlier than in the conventional design. During the backward movement of the hammer body 9, as shown in Fig. As shown in Figure 11, the compressed air is continuously released through the cylindrical gap 96 and various air outlet holes 36. As in the first embodiment, the impact force of the backward-moving hammer body 9 is continuously weakened, so that when the hammer body 9 reaches the end of its travel, as shown in Figure 11, the compressed air is continuously released through the cylindrical gap 96 and various air outlet holes 36. As in the first embodiment, the impact force of the backward-moving hammer body 9 is continuously reduced, so that when the hammer body 9 reaches the end of its travel, as shown in Figure 11, the impact force is continuously reduced. Fig. Figure 12 shows that the vibration is greatly reduced.

Claims

[1] Pneumatic impact tool with vibration-damping structure, with a handle (1) having a recess (11) and an air inlet channel (12) connected to the recess (11), wherein a switch (13) is provided in the air inlet channel (12); a cylindrical element (2) which is arranged in the recess (11), wherein a switching valve (22) is provided in the cylindrical element (2), wherein a through-hole (21) connected to the air inlet channel (12) is formed on the side wall of the cylindrical element (2), through which the compressed air is introduced into the switching valve (22); an inner tube (3) having an annular wall (31) and a cavity (32) surrounded by the annular wall (31), the annular wall (31) extending in the cylindrical element (2), a hammer body (4) being arranged in the cavity (32) which is in close contact with the annular wall (31), thereby dividing the cavity (32) into a front chamber (321) and a rear chamber (322), a tool head (5) being able to be attached to the front end of the inner tube (3), the annular wall (31) being provided with at least one air outlet hole (36) through which the cavity (32) is connected to the outside air, a long channel (33) being formed in the annular wall (31) connecting the switching valve (22) and the front chamber (321), the long channel (33) having a first air inlet opening (34) at the front chamber (321) and at the rear chamber (322) forms a second air inlet opening (35) which is connected to the switching valve (22),and wherein the compressed air can be introduced into the front chamber (321) through the first air inlet opening (34) or into the rear chamber (322) through the second air inlet opening (35); wherein, the hammer body (4) has a head (41) near the first air inlet opening (34) and an end (42) near the second air inlet opening (35), characterized by , that A channel is formed on the outer circumferential surface (43) of the hammer body (4), the channel extending to the head (41) and communicating with the front chamber (321), the channel not extending to the end (42) so that the channel is not communicating with the rear chamber (322), wherein when compressed air is introduced into the rear chamber (322) through the second air inlet opening (35), the compressed air pushes the hammer body (4), thus moving it forward towards the tool head (5), and when compressed air is introduced into the front chamber (321) through the first air inlet opening (34), the compressed air moves the hammer body (4) backward away from the tool head (5), and wherein when the channel communicates with the air outlet hole (36), the compressed air in the front chamber (321) is released through the channel and the air outlet hole (36), so that the pressure force on the hammer body (4) is reduced, wherein the channel is formed by a spiral groove (44) of the outer circumferential surface (43) of the hammer body (4), wherein the annular wall (31) is provided with three air outlet holes (36) and the distances between the air outlet holes (36) and the tool head (5) are different, and wherein, when the hammer body (4) moves into the position in which it touches the tool head (5), the groove (44) is connected to two air outlet holes (36) which are closest to the tool head (5). [2] Pneumatic impact tool with vibration-damping structure according to claim 1, characterized by , that the distances between the air outlet holes (36) and the tool head (5) are not greater than half the total length of the cavity (32).

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