Electric hammer gear adjustment device

Abstract

A hammer drill gear shifting device includes a cylinder arranged axially, a piston and an impact block located inside the cylinder, and a transmission gear and a clutch assembly sleeved on the cylinder. An air chamber is formed among the cylinder, the piston and the impact block. The transmission gear drives the cylinder to rotate together through the clutch assembly, and the clutch assembly includes a clutch sleeve connected to the transmission gear. The cylinder is provided with an exhaust hole penetrating through the outer wall of the cylinder and communicating with the air chamber. The clutch sleeve is provided with a rear circumferential wall portion fitting on the outer wall of the cylinder and a through hole penetrating through the rear circumferential wall portion. The clutch sleeve moves axially and has a heavy hammer gear and a light hammer gear. When the clutch sleeve is in the heavy hammer gear, the inner wall surface of the rear circumferential wall portion fits on the exhaust hole, and the hammer drill hammers at a normal speed. When the clutch sleeve is in the light hammer gear, the through hole of the clutch sleeve communicates with the exhaust hole of the cylinder, and part of the gas in the air chamber is discharged outwards, so as to achieve the effect of reducing the hammering force.

Description

Technical Field

[0001] The present invention relates to the field of hammer and pick power tools, and particularly to a hammer drill gear adjustment device for a hammer drill. Background Art

[0002] Hammer and pick power tools (such as hammer drills, demolition hammers, etc.), as a kind of power tool, utilize the principle of piston movement to compress gas and impact the drill bit to achieve hammering and chiseling functions; users do not need to exert much effort, and can drill holes in hard materials such as concrete, bricks, and stones, which are very popular among users. Currently, the hammer drills on the market are added with a light hammer function, which is used for chiseling in relatively soft geological conditions, wooden boards and other light working occasions, so as to meet the needs of customers for various working occasions. In order to achieve the light hammer function, it is necessary to adjust the duty cycle of the circuit board to reduce the output power, thereby reducing the hammering energy to achieve the light hammer function; however, while reducing the hammering energy, it also reduces the rotational speed of the output shaft, sacrificing work efficiency.

[0003] In view of this, it is necessary to provide an improved hammer drill gear adjustment device to overcome the defects of the prior art. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a hammer drill gear adjustment device with a light hammer gear, which can meet the use requirements of various working occasions without affecting the performance.

[0005] The technical solution adopted by the present invention to solve the problems of the prior art is: a hammer drill gear adjustment device, including a cylinder arranged axially, a piston and an impact block located in the cylinder, and a transmission gear and a clutch assembly sleeved on the cylinder. The piston makes an axial reciprocating motion in the cylinder to drive the impact block to make an axial impact motion. An air chamber is formed between the cylinder, the piston and the impact block. The transmission gear drives the cylinder to rotate together through the clutch assembly, and the clutch assembly includes a clutch sleeve connected to the transmission gear. The cylinder is provided with an exhaust hole penetrating the outer wall of the cylinder and communicating with the air chamber. The clutch sleeve is provided with a rear circumferential wall portion fitting on the outer wall of the cylinder and a through hole penetrating the rear circumferential wall portion. The clutch sleeve moves axially and has a heavy hammer gear and a light hammer gear. When the clutch sleeve is in the heavy hammer gear, the inner wall surface of the rear circumferential wall portion fits on the exhaust hole. When the clutch sleeve is in the light hammer gear, the through hole of the clutch sleeve communicates with the exhaust hole of the cylinder.

[0006] A further improvement solution is as follows: The clutch sleeve is located in front of the transmission gear. The clutch sleeve is provided with a first engaging portion at the rear end of the rear circumferential wall portion. The transmission gear is provided with a second engaging portion at the front end. The second engaging portion engages with the first engaging portion so that the clutch sleeve rotates together with the transmission gear.

[0007] A further improvement solution is as follows: The clutch sleeve further has a pure hammering gear position. At this time, the second engaging portion and the first engaging portion are separated from each other, and the transmission gear does not drive the clutch sleeve to rotate.

[0008] A further improvement solution is as follows: The clutch sleeve is provided with a front circumferential wall portion at the front end of the rear circumferential wall portion and a stepped portion connecting the front circumferential wall portion and the rear circumferential wall portion. The radius of the front circumferential wall portion is greater than the radius of the rear circumferential wall portion, so that a receiving portion is formed between the inner wall of the front circumferential wall portion and the outer wall of the cylinder.

[0009] A further improvement solution is as follows: The clutch assembly includes a blocking portion, an elastic member and a clutch member received in the receiving portion. The blocking portion is fixed on the inner wall of the front circumferential wall portion. The elastic member is located between the blocking portion and the clutch member so that the clutch member abuts against the stepped portion of the clutch sleeve.

[0010] A further improvement solution is as follows: The blocking portion includes a pressing plate sleeved on the cylinder and a limiting member. The front end of the elastic member abuts against the rear end face of the pressing plate. The clutch sleeve is provided with an annular groove recessed from the inner wall of the front circumferential wall portion. The limiting member is a wire snap ring or a C-shaped snap ring partially received in the groove and abuts against the front end face of the pressing plate to limit the axial forward movement of the pressing plate.

[0011] A further improvement solution is as follows: The clutch member is provided with an annular portion sleeved on the outer circumference of the cylinder and a pin key protruding inward from the inner wall surface of the annular portion. The cylinder is provided with a key groove on the outer wall. The pin key is slidably connected to the key groove along the axis. The clutch member moves axially relative to the cylinder and rotates together with the cylinder.

[0012] A further improvement solution is as follows: The clutch member is provided with a protrusion protruding from the annular portion toward the stepped portion. The clutch sleeve is provided with a groove on the inner wall of the stepped portion that engages with the protrusion. When the clutch member and the clutch sleeve are engaged, there is an engaging force between the protrusion and the groove. The clutch member moves axially along with the clutch sleeve to change the engaging force between the clutch member and the clutch sleeve.

[0013] A further improvement solution is as follows: The first engaging portion of the clutch sleeve engages with the second engaging portion of the transmission gear, and the transmission gear drives the cylinder to rotate together through the clutch assembly; when the cylinder is blocked and the separating force moment of the cylinder is greater than the engaging force, the separating member disengages from the clutch sleeve.

[0014] A further improvement solution is as follows: When the first engaging portion of the clutch sleeve is fully engaged with the second engaging portion of the transmission gear, the engaging force between the separating member and the clutch sleeve reaches the minimum value; when the first engaging portion of the clutch sleeve is not engaged with the second engaging portion of the transmission gear, the engaging force between the separating member and the clutch sleeve reaches the maximum value.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The cylinder is provided with an exhaust hole penetrating through the outer wall of the cylinder and communicating with the air chamber, the clutch sleeve is provided with a rear circumferential wall portion fitting on the outer wall of the cylinder and a through hole penetrating through the rear circumferential wall portion, and the clutch sleeve moves axially and has a heavy hammer gear position and a light hammer gear position. When the clutch sleeve is in the heavy hammer gear position, the inner wall surface of the rear circumferential wall portion fits on the exhaust hole, and the compressed gas in the air chamber does not decrease, and the electric hammer hammers at a normal speed; when the clutch sleeve is in the light hammer gear position, the through hole of the clutch sleeve communicates with the exhaust hole of the cylinder, and part of the compressed gas in the air chamber is discharged outwards. By reducing the amount of compressed gas in the air chamber, the effect of reducing the hammering is achieved. The electric hammer gear position adjusting device adds a light hammer gear position without affecting the performance, and is used for light working occasions such as softer geological conditions and wooden boards, meeting the needs of customers for various working occasions. [Description of the Drawings]

[0016] The following further describes in detail the specific embodiments of the present invention with reference to the drawings:

[0017] Figure 1 is the front view of the electric hammer according to the preferred embodiment of the present invention;

[0018] Figure 2 is Figure 1 the three-dimensional schematic diagram of the electric hammer gear position adjusting device in the electric hammer shown;

[0019] Figure 3 is Figure 2 the exploded schematic diagram of the electric hammer gear position adjusting device shown;

[0020] Figure 4 is Figure 2 the sectional view of the electric hammer gear position adjusting device shown;

[0021] Figure 5 is Figure 2 the sectional view of the electric hammer gear position adjusting device when it is in the light hammer gear position shown.

[0022] Meanings of the reference numerals in the drawings:

[0023] 100. Electric hammer gear adjustment device; 10. Cylinder; 11. Air chamber; 12. Keyway; 13. Exhaust hole; 20. Transmission gear; 21. Second engaging portion; 30. Piston; 31. Impact block; 32. Connecting rod; 321. Stud; 40. Clutch sleeve; 41. Rear peripheral wall portion; 42. Front peripheral wall portion; 420. Accommodating cavity; 43. Step portion; 44. First engaging portion; 45. Through hole; 50. Clutch member; 51. Ring portion; 52. Key pin; 53. Projection; 60. Elastic member; 70. Stopping portion; 71. Pressure plate; 72. Limiting member; 80. Adjusting knob; 200. Electric hammer; 201. Main body portion; 202. Holding portion; 203. Output portion [Detailed implementation manners]

[0024] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the terms indicating orientation or positional relationship such as "upper", "lower", "front", "rear", etc. are only based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device / component referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0025] Please refer to Figures 1 to 5 Shown is an electric hammer 200 according to a preferred embodiment of the present invention, which is widely used in fields such as construction and building. The electric hammer 200 includes a main body portion 201, a holding portion 202 connected to the rear end of the main body portion 201, and an output portion 203 connected to the front end of the main body portion 201. The holding portion 202 is for a user to hold to operate the electric hammer 200, and the output portion 203 is for outputting the power of the electric hammer 200 outward. The electric hammer 200 further includes a motor (not shown) located in the main body portion 201, an electric hammer torque adjustment device 100 connected to the motor, and an adjusting knob 80 located on the main body portion 201. The adjusting knob 80 is used to perform corresponding gear adjustment and torque adjustment on the electric hammer torque adjustment device 100.

[0026] Combine Figure 2As shown, the electric hammer gear shifting device 100 includes a cylinder 10 arranged along the axial direction, a transmission gear 20 sleeved on the cylinder 10, a clutch assembly (not labeled), a piston 30 and an impact block 31 located inside the cylinder 10. The motor meshes with the transmission gear 20. When the electric hammer 200 is working normally, the motor drives the clutch assembly to rotate through the transmission gear 20 and drives the cylinder 10 to rotate together. One end of the connecting rod 32 is fixedly connected to the piston 30 through a pin 321, and the other end is connected to the motor. The motor drives the piston 30 to make an axial reciprocating motion inside the cylinder 10 to drive the impact block 31 to make an axial impact motion. At the same time, an air cavity 11 is formed among the cylinder 10, the piston 30 and the impact block 31, and the cylinder 10 is provided with an exhaust hole 13 penetrating through its outer wall and communicating with the air cavity 11.

[0027] Please refer to Figures 3 to 5 As shown, the clutch assembly is used to interrupt the output of torque when the electric hammer 200 is overloaded or jammed. The clutch assembly includes a clutch sleeve 40 connected to the transmission gear 20, a clutch member 50 sleeved on the outer periphery of the cylinder 10, an elastic member 60 and a stop portion 70. The elastic member 60 is a return spring, and the clutch sleeve 40, the clutch member 50 and the cylinder 10 have the same rotation axis.

[0028] The clutch sleeve 40 is located in front of the transmission gear 20 and is provided with a rear peripheral wall portion 41 attached to the outer wall of the cylinder 10, a front peripheral wall portion 42 located at the front end of the rear peripheral wall portion 41, and a step portion 43 connecting the front peripheral wall portion 42 and the rear peripheral wall portion 41. The radius of the front peripheral wall portion 42 is greater than that of the rear peripheral wall portion 41, so that a receiving portion 420 is formed between the inner wall of the front peripheral wall portion 42 and the outer wall of the cylinder 10. The stop portion 70, the elastic member 60 and the clutch member 50 are received in the receiving portion 420.

[0029] The clutch sleeve 40 is provided with a first engaging portion 44 located at the rear end of the rear peripheral wall portion 41 and a through hole 45 penetrating through the rear peripheral wall portion 41; the transmission gear 20 is provided with a second engaging portion 21 located at the front end, and the second engaging portion 21 engages with the first engaging portion 44 so that the clutch sleeve 40 rotates together with the transmission gear 20. At the same time, the clutch sleeve 40 moves axially and has a heavy hammer gear and a light hammer gear. When the clutch sleeve 40 is in the heavy hammer gear, the inner wall surface of the rear peripheral wall portion 41 is attached to the exhaust hole 13 of the cylinder 10, and the compressed gas in the air cavity 11 does not decrease, and the electric hammer hammers at a normal speed. When the clutch sleeve 40 is in the light hammer gear, the through hole 45 of the clutch sleeve 40 communicates with the exhaust hole 13 of the cylinder 10, and part of the compressed gas in the air cavity 11 is discharged outwards, and the hammering effect is reduced by reducing the amount of compressed gas in the air cavity 11.

[0030] The stop portion 70 is fixed on the inner wall of the front peripheral wall portion 42. The elastic member 60 is located between the stop portion 70 and the clutch member 50, so that the clutch member 50 abuts against the stepped portion 43 of the clutch sleeve 40. The stop portion 70 includes a pressing plate 71 sleeved on the cylinder 10 and a limiting member 72. The front end of the elastic member 60 abuts against the rear end face of the pressing plate 71. The clutch sleeve 40 is provided with an annular card slot (not labeled) recessed from the inner wall of the front peripheral wall portion 42. The limiting member 72 is a circlip or a C-shaped snap ring partially received in the card slot and abuts against the front end face of the pressing plate 71 to limit the axial forward movement of the pressing plate 71; thereby ensuring that the elastic member 60 and the clutch member 50 will not escape from the accommodation cavity 420.

[0031] The clutch member 50 is provided with an annular portion 51 sleeved on the outer periphery of the cylinder 10, a pin key 52 protruding inward from the inner wall surface of the annular portion 51, and a protrusion 53 protruding from the annular portion 51 toward the stepped portion 43. The cylinder 10 is provided with a key groove 12 on its outer wall. The pin key 52 is slidably connected to the key groove 12 in the axial direction, so that the clutch member 50 can move axially relative to the cylinder 10 and rotate together with the cylinder 10. The clutch sleeve 40 is provided with a groove (not shown) located on the inner wall of the stepped portion 43 and engaging with the protrusion 53. When the clutch member 50 is engaged with the clutch sleeve 40, there is an engaging force between the protrusion 53 and the groove; at the same time, the clutch member 50 moves axially along with the clutch sleeve 40 to change the engaging force between the clutch member 50 and the clutch sleeve 40.

[0032] Specifically, when the first engaging portion 44 of the clutch sleeve 40 is engaged with the second engaging portion 21 of the transmission gear 20, the transmission gear 20 can drive the cylinder 10 to rotate together through the clutch assembly. In this case, when the cylinder 10 is blocked and the disengagement torque of the cylinder 10 is greater than the engaging force, the clutch member 50 is disengaged from the clutch sleeve 40 and jumps gears to achieve the interruption of the torque output when the electric hammer 200 is overloaded or blocked.

[0033] Meanwhile, the clutch sleeve 40 is further provided with an annular groove (not labeled) recessed inward from the inner wall surface of the rear peripheral wall portion 41. The annular groove overlaps with the through hole 45 in the axial position, that is, the through hole 45 communicates with the annular groove. When the clutch sleeve 40 is in the light hammer gear position, the exhaust hole 13 of the cylinder 10 communicates with the through hole 45 and also communicates with the annular groove. In this case, when the cylinder 10 is blocked and the clutch member 50 jumps gears, the cylinder 10 rotates relative to the clutch sleeve 40. At this time, even if the circumferential positions of the through hole 45 of the clutch sleeve 40 and the exhaust hole 13 of the cylinder 10 are misaligned, as long as the clutch sleeve 40 is in the light hammer gear position, the annular groove of the clutch sleeve 40 can ensure that the exhaust hole 13 of the cylinder 10 is always communicated with the through hole 45 of the clutch sleeve 40, so that the compressed gas in the air chamber 11 can be smoothly discharged outwards, thereby achieving the effect of reducing the hammering force.

[0034] Furthermore, the number of the through holes 45 of the clutch sleeve 40 is an integer multiple of the number of the protrusions 53 of the clutch member 50. This ensures that when the cylinder 10 is blocked and the clutch member 50 jumps gears, even if the cylinder 10 rotates relative to the clutch sleeve 40, the through holes 45 can still be aligned and communicated with the exhaust holes 13, so that the compressed gas in the air chamber 11 can be smoothly discharged outwards, thereby achieving the effect of reducing the hammering force. At this time, the above-mentioned annular groove may not be provided on the clutch sleeve 40. In this embodiment, the number of the through holes 45 of the clutch sleeve 40 is the same as the number of the protrusions 53 of the clutch member 50.

[0035] In this embodiment, the clutch sleeve 40 further has a pure hammering gear position. At this time, the second engaging portion 21 and the first engaging portion 44 are separated from each other, and the transmission gear 20 does not drive the clutch sleeve 40 to rotate. The cylinder 10 only has an impact motion. Moreover, when the first engaging portion 44 of the clutch sleeve 40 is completely engaged with the second engaging portion 21 of the transmission gear 20, the engaging force between the clutch member 50 and the clutch sleeve 40 reaches the minimum value; when the first engaging portion 44 of the clutch sleeve 40 is not engaged with the second engaging portion 21 of the transmission gear 20, that is, when the clutch sleeve 40 is in the pure hammering gear position, the engaging force between the clutch member 50 and the clutch sleeve 40 reaches the maximum value.

[0036] In the present invention, the cylinder 10 is provided with an exhaust hole 13 that penetrates the outer wall of the cylinder 10 and communicates with the air chamber 11. The clutch sleeve 40 is provided with a rear circumferential wall portion 41 that fits against the outer wall of the cylinder 10 and a through hole 45 that penetrates the rear circumferential wall portion 41. The clutch sleeve 40 moves axially and has a heavy hammer gear position and a light hammer gear position. When the clutch sleeve 40 is in the heavy hammer gear position, the inner wall surface of the rear circumferential wall portion 41 fits against the exhaust hole 13, and the compressed gas in the air chamber 11 does not decrease, and the electric hammer 200 hammers at a normal speed. When the clutch sleeve 40 is in the light hammer gear position, the through hole 45 of the clutch sleeve 40 communicates with the exhaust hole 13 of the cylinder 10, and part of the compressed gas in the air chamber 11 is discharged outward. By reducing the amount of compressed gas in the air chamber 11, the effect of reducing the hammering is achieved. The electric hammer gear adjustment device 100 adds a light hammer gear position without affecting the performance, and is used for light working occasions such as softer geological conditions and wooden boards, meeting the needs of customers for various working occasions.

[0037] The present invention is not limited to the above specific embodiments. Those of ordinary skill in the art can easily understand that there are many alternative solutions for the electric hammer gear adjustment device of the present invention without departing from the principles and scope of the present invention. The protection scope of the present invention shall be subject to the content of the claims.

Claims

1. An electric hammer gear shifting device, comprising a cylinder arranged axially, a piston and an impact block located in the cylinder, and a transmission gear and a clutch assembly sleeved on the cylinder. The piston makes an axial reciprocating motion in the cylinder to drive the impact block to make an axial impact motion. An air chamber is formed among the cylinder, the piston and the impact block. The transmission gear drives the cylinder to rotate together through the clutch assembly, and the clutch assembly includes a clutch sleeve connected to the transmission gear; it is characterized in that: The cylinder is provided with an exhaust hole that penetrates the outer wall of the cylinder and communicates with the air chamber. The clutch sleeve is provided with a rear circumferential wall portion that fits against the outer wall of the cylinder and a through hole that penetrates the rear circumferential wall portion. The clutch sleeve moves axially and has a heavy hammer gear position and a light hammer gear position. When the clutch sleeve is in the heavy hammer gear position, the inner wall surface of the rear circumferential wall portion fits against the exhaust hole. When the clutch sleeve is in the light hammer gear position, the through hole of the clutch sleeve communicates with the exhaust hole of the cylinder.

2. The electric hammer gear adjustment device according to claim 1, characterized in that: The clutch sleeve is located in front of the transmission gear. The clutch sleeve is provided with a first engaging portion at the rear end of the rear circumferential wall portion. The transmission gear is provided with a second engaging portion at the front end. The second engaging portion engages with the first engaging portion so that the clutch sleeve rotates together with the transmission gear.

3. The electric hammer gear adjustment device according to claim 2, wherein: The clutch sleeve also has a pure hammering gear position. At this time, the second engaging portion and the first engaging portion are separated from each other, and the transmission gear does not drive the clutch sleeve to rotate.

4. The electric hammer gear adjustment device according to claim 2, wherein: The clutch sleeve is provided with a front circumferential wall portion at the front end of the rear circumferential wall portion and a stepped portion connecting the front circumferential wall portion and the rear circumferential wall portion. The radius of the front circumferential wall portion is greater than the radius of the rear circumferential wall portion, so that a receiving portion is formed between the inner wall of the front circumferential wall portion and the outer wall of the cylinder.

5. The electric hammer gear adjustment device according to claim 4, characterized in that: The clutch assembly includes a blocking portion, an elastic member, and a clutch member received in the receiving portion. The blocking portion is fixed to the inner wall of the front circumferential wall portion. The elastic member is located between the blocking portion and the clutch member so that the clutch member abuts against the stepped portion of the clutch sleeve.

6. The electric hammer gear adjustment device according to claim 5, wherein: The blocking portion includes a pressing plate sleeved on the cylinder and a limiting member. The front end of the elastic member abuts against the rear end face of the pressing plate. The clutch sleeve is provided with an annular groove recessed from the inner wall of the front circumferential wall portion. The limiting member is a wire retaining ring or a C-shaped snap ring partially received in the groove and abuts against the front end face of the pressing plate to limit the axial forward movement of the pressing plate.

7. The electric hammer gear adjustment device according to claim 5, characterized in that: The clutch member is provided with an annular portion sleeved on the outer circumference of the cylinder and a pin key protruding inward from the inner wall surface of the annular portion. The cylinder is provided with a key groove on the outer wall. The pin key is slidably connected to the key groove axially. The clutch member moves axially relative to the cylinder and rotates together with the cylinder.

8. The electric hammer gear adjustment device according to claim 7, characterized in that: The clutch member is provided with a protrusion protruding from the annular portion toward the stepped portion. The clutch sleeve is provided with a groove on the inner wall of the stepped portion that engages with the protrusion. When the clutch member and the clutch sleeve are engaged, there is an engaging force between the protrusion and the groove. The clutch member moves axially along with the clutch sleeve to change the engaging force between the clutch member and the clutch sleeve.

9. The electric hammer gear adjustment device according to claim 8, characterized in that: The first engaging portion of the clutch sleeve engages with the second engaging portion of the transmission gear; when the cylinder is blocked and the separation torque of the cylinder is greater than the engaging force, the clutch member and the clutch sleeve are disengaged.

10. The electric hammer gear adjustment device according to claim 8, characterized in that: When the first engaging portion of the clutch sleeve is fully engaged with the second engaging portion of the transmission gear, the engaging force between the clutch member and the clutch sleeve reaches the minimum value; when the first engaging portion of the clutch sleeve is not engaged with the second engaging portion of the transmission gear, the engaging force between the clutch member and the clutch sleeve reaches the maximum value.

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