Internally driven mechanical percussion power tool

Abstract

The application discloses an inner driving mechanical striking electric tool, which comprises a shell, a driving shaft rotatably arranged in the shell, a striking force storage guide rail arranged on the driving shaft, a ring-shaped reciprocating striking block sleeved with the driving shaft, an energy storage spring arranged at one end of the reciprocating striking block, the other end of the energy storage spring being close to a driving end and being limited by the driving shaft, the reciprocating striking block being combined with an impact surface of an output shaft under the action of the energy storage spring, a poking pin fixedly arranged on the inner side of the reciprocating striking block, the outer circular surface of the poking pin being combined with the surface of the striking force storage guide rail, the other end of the poking pin being arranged in a rectangular guide groove, the guide groove being arranged on the shell, the driving shaft further comprising a rotating separation sleeve sliding along the axial direction of the driving shaft, a ring groove arranged on the outer part of the rotating separation sleeve, and a poking device arranged in the ring groove and used for adjusting the rotating separation sleeve. The application has the advantages of high durability and low power loss.

Description

Technical Field

[0001] This invention relates to the field of power tools, and more particularly to an internally driven mechanical striking power tool. Background Technology

[0002] Most existing electric hammer drills utilize a motor-driven reducer to drive a connecting rod, which in turn pushes a piston in reciprocating motion. Changes in air pressure within a cylinder drive a striking block to strike the drill bit, achieving the hammering function. The drill bit's rotation is achieved by a small portion of the motor's output torque being transmitted to another reduction and separation mechanism. When separated, the drill bit remains stationary, functioning as a pick; when engaged, the drill bit rotates, functioning as a hammer drill. This type of electric hammer drill suffers from low efficiency due to the complexity of the hammering conversion mechanism. Furthermore, the piston and striking block within the conversion mechanism's cylinder rely on sliding friction, reducing efficiency and increasing wear due to friction with the cylinder, leading to a sharp increase in power loss and potentially rendering the drill unusable. The complexity of the hammering conversion mechanism also increases manufacturing costs. Another type of hammer drill, capable of both hammer drilling and electric drilling but not pick functionality, uses an axial ratchet slidingly mounted on the drill's output shaft and a ratchet with reversed teeth mounted on the drill chuck's connecting shaft. The axial displacement generated by the ratchet's rotation and separation gap achieves the hammer drilling function. The hammering force is generated by the up-and-down vibration when the ratchet slides between the two ratchet teeth. The sliding resistance between the ratchet teeth is very large, resulting in high power loss. Therefore, it is impossible to make the ratchet teeth high, and the energy stored when the ratchet retracts cannot be large. Consequently, the output hammering force is very small, and the applicable range is very limited. Summary of the Invention

[0003] To address the drawbacks of complex conversion between the striking functions of electric hammer drills and electric picks, this invention provides an internally driven mechanical striking electric tool that is more durable and has lower power consumption.

[0004] This invention is achieved through the following technical solution:

[0005] An internally driven mechanical striking electric tool includes a housing. One end of the housing is a drive end for a motor, and the other end is an output end for an output shaft. A drive shaft is rotatably mounted inside the housing. The drive shaft is divided into a drive connection section, a striking conversion section, and an output connection section from the drive end to the output end. The drive connection section includes a reduction mechanism. The output connection section is externally fitted with the output shaft, and the output shaft has an impact surface extending beyond the outer wall of the output connection section. The striking conversion section includes a striking energy storage guide rail, which is a continuous closed curve guide rail containing a storage point and a striking point, located outside the striking conversion section. The striking point is adjacent to the storage point and located in the opposite direction to the movement direction of the storage point. An annular reciprocating striking block is externally fitted to the striking conversion section. One end of the reciprocating striking block is equipped with an energy storage spring, and the other end of the energy storage spring is close to the drive end and is upper-limited by the drive shaft. The reciprocating striking block has a striking surface at one end near the output shaft, which is in contact with the impact surface of the output shaft under the action of the energy storage spring. A detonating pin is fixedly installed inside the reciprocating striking block, arranged radially along the drive shaft. Under the action of the energy storage spring, the outer surface of the detonating pin is in contact with the surface of the striking energy storage guide rail. The other end of the detonating pin passes through the reciprocating striking block and slides within a rectangular guide groove, which is located on the housing. The long side of the guide groove is along the axis of the drive shaft. The diameter of the output connection part is smaller than that of the striking conversion part. A rotating separation sleeve that slides axially along the drive shaft is located close to the striking conversion part of the output connection part. The rotating separation sleeve is slidably connected to the output connection part via an internal spline, and its other end is connected to the output shaft via an external spline. An annular groove is provided on the outside of the rotating separation sleeve, and a detonating device for adjusting the rotating separation sleeve is provided within the annular groove.

[0006] Preferably, the actuating device includes an actuating fork disposed in an annular groove, the actuating fork being connected to an actuating handle, a notch being provided on one side of the reciprocating striking block, and the actuating handle extending from the notch at the striking end of the reciprocating striking block to the outside of the housing.

[0007] Preferably, the strike conversion part is provided with ratchet-shaped protrusions, the tips of the ratchet-shaped protrusions facing the drive end, one side of the tip is an inclined surface relative to the axis of the drive shaft, and the other side of the tip is a plane coplanar with the axis of the drive shaft. The ratchet-shaped protrusions are evenly distributed on the outer surface of the strike conversion part and form a continuous closed curve; the closed curve forms the strike power storage guide rail.

[0008] Preferably, at least two ratchet protrusions are provided, and the number of ratchet protrusions is a multiple of the number of actuating pins.

[0009] Preferably, the output shaft is sleeved outside the output connection part, and a return spring is provided between the end of the output connection part and the output shaft.

[0010] Preferably, a steel ball is provided between the reset spring and the output connection portion.

[0011] Preferably, a stop is provided at the position where the strike conversion part is connected to the drive connection part, and a pressure bearing is provided on one side of the strike conversion part, with the energy storage spring pressing against the pressure bearing.

[0012] Preferably, a slot is provided on the inner wall of the housing at the connection between the output connection part and the output shaft, and a buffer washer is provided in the slot. When the energy storage spring is in the fully extended state, the buffer washer is in contact with the striking surface of the reciprocating striking block.

[0013] Preferably, the output shaft is housed within the housing via a ball bearing, and the connection point between the output shaft and the drive shaft is tapered.

[0014] Preferably, the reduction mechanism includes three circumferentially arranged double planetary gears, the axles of which are fixed on the drive seat. The drive seat and the drive shaft are integrated, and a hole is provided in the center of the drive seat for the motor shaft teeth to extend into and mesh with the double planetary gears.

[0015] Compared with existing technologies, this invention uses a drive shaft with a closed-curve guide rail to drive the reciprocating striking block to move up and down. It uses an energy storage spring to convert elastic potential energy into impact energy. Since the striking point and the energy storage point are both located on the extension line of the energy storage spring's force, there is almost no resistance during the release of elastic potential energy, resulting in low power loss. Therefore, the ratchet can be made higher to obtain a greater hammering force. Throughout the process, there are only frictional resistances between the actuating pin and the guide groove, as well as frictional resistances between the striking energy storage rail and the actuating pin. By simply improving the strength and machining accuracy of the actuating pin, power consumption can be reduced while increasing durability. Attached Figure Description

[0016] Figure 1 This is a cross-sectional structural schematic diagram of an embodiment of an internally driven mechanical power tool according to the present invention;

[0017] Figure 2 This is a schematic diagram of the drive shaft (excluding the reduction mechanism) of an embodiment of an internally driven mechanical percussion power tool according to the present invention.

[0018] Figure 3 This is a cross-sectional structural diagram of the drive shaft (excluding the reduction mechanism) of an embodiment of an internally driven mechanical power tool according to the present invention.

[0019] The attached figures are labeled as follows:

[0020] 1. Housing; 2. Drive end; 3. Output end; 4. Drive shaft; 5. Reduction mechanism; 6. Impact energy storage guide rail; 7. Reciprocating impact block; 8. Energy storage spring; 9. Actuating pin; 10. Guide groove; 11. Rotating separation sleeve; 12. Internal spline; 13. External spline; 14. Annular groove; 15. Actuating fork; 16. Energy storage point; 17. Strike point; 18. Output shaft; 19. Double planetary gear; 20. Drive seat; 21. Gear ring; 22. Razor-shaped protrusion; 23. Return spring; 24. Steel ball; 25. Pressure bearing; 26. Buffer washer; 27. Ball bearing; 28. Impact drill bit hole. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0023] like Figure 1-3As shown, an internally driven mechanical impact electric tool includes a housing 1, with a drive end 2 at one end of the housing 1, where a motor is installed, and an output end 3 at the other end, where an output shaft 18 is installed. The output shaft 18 has an impact drill bit hole 28 at its end for mounting an impact drill bit. A drive shaft 4 is rotatably mounted inside the housing 1. The drive shaft 4 is divided into a drive connection section, an impact conversion section, and an output connection section from the drive end 2 to the output end 3. The drive connection section is equipped with a reduction mechanism 5. The output connection section is externally fitted with the output shaft 18, which has an impact surface extending beyond the outer wall of the output connection section. The impact conversion section is equipped with an impact energy storage guide rail 6, which is a continuous closed curve guide rail consisting of an energy storage point 16 and an impact point 17 located outside the impact conversion section. The impact point 17 is adjacent to the energy storage point 16 and located in the opposite direction to the movement direction of the energy storage point 16. An annular reciprocating impact block 7 is externally fitted to the impact conversion section. One end of the reciprocating impact block 7 is connected to an energy storage spring 8, and the other end of the energy storage spring 8 is near... The reciprocating impact block 7 is located near the drive end 2 and is limited by the drive shaft 4. The energy storage spring 8 is separated from the drive shaft 4 by the pressure bearing 25 to prevent the energy storage spring 8 from bearing torque. One end of the reciprocating impact block 7 near the output shaft 18 is in contact with the end of the output shaft 18 under the action of the energy storage spring 8. A deflector pin 9 is fixedly provided on the inner side of the reciprocating impact block 7. The deflector pin 9 is arranged radially along the drive shaft 4. Under the action of the energy storage spring 8, the outer surface of the deflector pin 9 is in contact with the surface along the impact energy storage guide rail 6. The other end of the deflector pin 9 passes through the sliding end of the reciprocating impact block 7. The rotating release sleeve 11 is slidably mounted within a rectangular guide groove 10, which is located on the housing 1. The long side of the guide groove 10 is along the axis of the drive shaft 4. The diameter of the output connection part is smaller than that of the impact conversion part. A rotating release sleeve 11, which can slide along the drive shaft 4, is located close to the impact conversion part. The rotating release sleeve 11 is slidably connected to the output connection part via an internal spline 12, and its other end is connected to the output shaft 18 via an external spline 13. An annular groove 14 is provided on the outside of the rotating release sleeve 11, and a toggle device is provided within the annular groove 14. The annular groove 14 is generally located near the impact conversion part. The toggle device generally includes a toggle fork 15. The toggle fork 15 is L-shaped, with a notch on one side of the reciprocating impact block 7. The toggle fork extends from the notch at the impact end of the reciprocating impact block 7 to the outside of the housing 1 and connects to the toggle handle. When the toggle handle is actuated, the rotating release sleeve 11 can be moved axially.

[0024] In this embodiment, when the electric hammer drill function is implemented, the motor drives the drive shaft 4 to rotate through the reduction mechanism 5. The drive shaft 4 drives the output shaft 18 to rotate through the rotating separation sleeve 11, thus realizing the basic function of the electric hammer drill. Since the position of the actuating pin 9 is restricted by the guide groove 10, it can only move up and down along the axial direction. When the drive shaft 4 rotates, the impact energy storage guide 6 rotates, and the actuating pin 9 moves along the surface of the impact energy storage guide 6, thereby driving the reciprocating impact block 7 to move. Due to the action of the energy storage spring 8, when the actuating pin 9 moves to the energy storage point 16, the energy storage spring 8 compresses and stores energy. After the actuating pin 9 passes the energy storage point 16, the energy storage spring 8 quickly releases energy, causing the actuating pin 9 to reach the impact point 17, driving the reciprocating impact block 7 to strike the output shaft 18, thereby realizing one striking cycle. In order to make the strike more powerful, the running trajectory of the actuating pin 9 from the energy storage point 16 to the impact point 17 is parallel to the axis of the drive shaft 4.

[0025] When the electric hammer function is activated, the output shaft 18 does not need to rotate. At this time, the rotating separation sleeve 11 is moved towards the output shaft 18 by the actuating fork 15, so that the inner spline 12 of the rotating separation sleeve 11 and the outer spline of the output connection part are separated, and the output shaft 18 loses its rotational driving force. For ease of operation, a slide groove can be provided on the housing 1, and the actuating handle extends out from the slide groove.

[0026] In a preferred embodiment of the present invention, the drive connection part is provided with a reduction mechanism 5 composed of double planetary gears 19. Generally, such as Figure 1 As shown, the device includes three circumferentially arranged double planetary gears 19. The axles of the double planetary gears 19 are fixed on the drive seat 20. The drive seat 20 has a central hole for the motor shaft teeth to extend into and mesh with the double planetary gears 19 in multiple connections. The gear ring 21 meshes with the double planetary gears 19 in fewer connections. This invention can also employ a general planetary reduction mechanism.

[0027] In a preferred embodiment of the present invention, such as Figure 2 As shown, the outer wall of the impact conversion section is provided with ratchet-shaped protrusions 22. The tips of the ratchet-shaped protrusions 22 face the drive end 2. One side of the tip is an inclined surface relative to the axis of the drive shaft 4, and the other side of the tip is a plane coplanar with the axis of the drive shaft 4. The ratchet-shaped protrusions 22 are evenly distributed on the outer surface of the impact conversion section, and form a continuous closed curve on one side of the tip. The tip is the energy storage point 16, and the lowest point is the impact point 17. In this structure, the impact point 17 and the energy storage point 16 are located on the extension line of the force of the energy storage spring 8. Due to the elastic potential energy, the reciprocating impact block 7 instantly moves from the energy storage point 16 to the impact point 17 without any friction, and the impact power loss is almost negligible. The number of strokes of one rotation of the drive shaft 4 is related to the number of ratchet-shaped protrusions 22. Under a fixed rotation speed, the more ratchet-shaped protrusions 22 there are, the higher the impact frequency. At least two ratchet-shaped protrusions 22 are provided, and the number of ratchet-shaped protrusions 22 must be a multiple of the number of actuating pins 9.

[0028] In a preferred embodiment of the present invention, such as Figure 1 As shown, the output shaft 18 is sleeved on the outside of the drive shaft 4, and a return spring 23 is provided between the end of the output connection of the drive shaft 4 and the output shaft 18. Since the drive shaft 4 cannot move axially when the output shaft 18 is struck by the reciprocating impact block 7, the return spring 23 can maintain an axial thrust on the drive shaft 4 in the direction of the reduction mechanism 5, maintain the stability of the structure, and avoid vibration. During operation, the impact drill bit installed in the impact drill hole 28 on the output shaft 18 rests on the working surface, compressing the return spring 23, so that the impact surface of the output shaft 18 moves closer to the reciprocating impact block 7 to receive the impact kinetic energy.

[0029] In a preferred embodiment of the present invention, such as Figure 1 As shown, a steel ball 24 is provided between the return spring 23 and the drive shaft 4. The steel ball 24 can prevent the return spring 23 and the drive shaft 4 from rotating together when the drive shaft 4 and the output shaft 18 are separated by the rotating separation sleeve 11, thereby improving the service life of the return spring 23.

[0030] In a preferred embodiment of the present invention, such as Figure 1 As shown, a stop is provided at the position where the strike conversion part connects to the drive connection part. A pressure bearing 25 is provided on one side of the strike conversion part. The energy storage spring 8 rests on the pressure bearing 25. The pressure bearing 25 serves as a rotational support for the drive shaft 4 and can prevent the torque of the drive shaft 4 from being transmitted to the energy storage spring 8. It also serves to counteract the reaction force when the drive shaft 4 drives the reciprocating strike block 7 to store energy.

[0031] In a preferred embodiment of the present invention, a groove is provided on the inner wall of the housing 1 at the connection between the output connection and the output shaft 18, and a buffer washer 26 is provided in the groove. When the energy storage spring 8 is in the fully extended state, the buffer washer 26 is in contact with the impact surface of the reciprocating impact block 7. When the impact drill bit installed in the impact drill bit hole 28 on the output shaft 18 is not supported by a working surface, it can limit the impact block and absorb part of the impact kinetic energy, thus playing a buffering role.

[0032] In a preferred embodiment of the present invention, the output shaft 18 is disposed within the housing 1 via a ball bearing 27. The connection point between the output shaft 18 and the drive shaft 4 is tapered to increase the contact area with the reciprocating impact block 7, making it less susceptible to damage when receiving impact kinetic energy.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An internally driven mechanical striking power tool, comprising a housing, wherein one end of the housing is a drive end for mounting a motor, and the other end is an output end for mounting an output shaft, characterized in that, A drive shaft is rotatably mounted inside the housing. From the drive end to the output end, the drive shaft is sequentially divided into a drive connection section, an impact conversion section, and an output connection section. The drive connection section is equipped with a reduction mechanism. The output connection section is externally fitted with the output shaft, and the output shaft has an impact surface extending beyond the outer wall of the output connection section. The impact conversion section is equipped with an impact energy storage guide rail, which is a continuous closed curve guide rail containing an energy storage point and an impact point, located outside the impact conversion section. The impact point is adjacent to the energy storage point and located in the opposite direction to the movement direction of the energy storage point. An annular reciprocating impact block is externally fitted to the impact conversion section. One end of the reciprocating impact block is equipped with an energy storage spring, and the other end of the energy storage spring is near the drive end and is upper-limited by the drive shaft. The end of the reciprocating impact block near the output shaft is the impact surface. The impact surface of the reciprocating striking block is in contact with the impact surface of the output shaft under the action of the energy storage spring; a deflecting pin is fixedly provided on the inner side of the reciprocating striking block, the deflecting pin is arranged radially along the drive shaft, and the outer circular surface of the deflecting pin is in contact with the surface of the striking energy storage guide rail under the action of the energy storage spring. The other end of the deflecting pin passes through the reciprocating striking block and is slidably disposed in a rectangular guide groove, the guide groove is disposed on the housing, and the long side of the guide groove is along the axial direction of the drive shaft; the diameter of the output connection part is smaller than that of the striking conversion part, and a rotating separation sleeve that slides axially along the drive shaft is provided at the position of the output connection part close to the striking conversion part. The rotating separation sleeve is slidably connected to the output connection part through an internal spline, and the other end of the rotating separation sleeve is connected to the output shaft through an external spline; an annular groove is provided on the outside of the rotating separation sleeve, and a deflecting device for adjusting the rotating separation sleeve is provided in the annular groove.

2. The internally driven mechanical striking electric tool according to claim 1, characterized in that, The actuating device includes an actuating fork disposed in an annular groove. A notch is provided on one side of the reciprocating striking block. The actuating fork extends from the notch at the striking end of the reciprocating striking block to the outside of the housing and is connected to the actuating handle.

3. The internally driven mechanical striking electric tool according to claim 1, characterized in that, The strike conversion section is provided with ratchet-shaped protrusions, the tips of which face the drive end. One side of the tip is an inclined surface relative to the axis of the drive shaft, and the other side of the tip is a plane coplanar with the axis of the drive shaft. The ratchet-shaped protrusions are evenly distributed on the outer surface of the strike conversion section and form a continuous closed curve; the closed curve forms the strike power storage guide rail.

4. The internally driven mechanical striking electric tool according to claim 3, characterized in that, At least two ratchet protrusions are provided, and the number of ratchet protrusions is a multiple of the number of actuating pins.

5. The internally driven mechanical striking electric tool according to claim 1, characterized in that, The output shaft is sleeved outside the output connection part, and a return spring is provided between the end of the output connection part and the output shaft.

6. The internally driven mechanical striking electric tool according to claim 5, characterized in that, A steel ball is provided between the reset spring and the output connection part.

7. The internally driven mechanical striking electric tool according to claim 1, characterized in that, A stop is provided at the position where the strike conversion part is connected to the drive connection part. A pressure bearing is provided on one side of the strike conversion part, and the energy storage spring rests on the pressure bearing.

8. The internally driven mechanical striking electric tool according to claim 1, characterized in that, A slot is provided on the inner wall of the housing where the output connection part connects to the output shaft. A buffer washer is provided in the slot. When the energy storage spring is in the fully extended state, the buffer washer is in contact with the striking surface of the reciprocating striking block.

9. The internally driven mechanical striking electric tool according to claim 1, characterized in that, The output shaft is mounted inside the housing via ball bearings, and the connection point between the output shaft and the drive shaft is tapered.

10. The internally driven mechanical striking power tool according to claim 1, characterized in that, The reduction mechanism includes three circumferentially arranged double planetary gears. The axles of the double planetary gears are fixed on the drive seat. The drive seat and the drive shaft are integrated. A hole is provided in the center of the drive seat for the motor shaft teeth to extend into and mesh with the double planetary gears.

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