Power tool

Abstract

The present invention relates to a power tool, which includes a housing, a motor, a transmission mechanism, and an impact mechanism received in the housing. The impact mechanism includes a cylinder and a striker, a guiding device, a hammer, and a piston disposed in the cylinder. When the striker moves in the direction opposite to the output direction, the second guiding portion sequentially supports the third section and the second section, and the diameter of the third section is smaller than that of the second section. By increasing the gap between the second guiding portion and the third section, the striker is tilted relative to the axis of the cylinder and then moves. When the power tool is idling, this tilt consumes the energy of the striker moving in the reverse direction to prevent the striker from taking the hammer away from the locking portion, preventing the hammer from impacting when idling and thus affecting the service life of the power tool; before the striker is impacted, the second guiding portion supports the second section. At this time, the axis of the striker coincides with the axis of the cylinder, the hammer impacts the striker in a straight line direction, and the striker outputs an impact in a straight line direction, increasing the energy transfer efficiency.

Description

[Technical Field]

[0001] The present invention relates to the field of power tools, and particularly to a power tool for performing impact or rotary impact operations on structures such as concrete and masonry. [Background Art]

[0002] Power tools such as electric hammers usually have a ram, a striker rod located within a cylinder, and a locking portion for locking the ram when the electric hammer is idling. When the electric hammer is idling, it is necessary to lock the ram within an extremely short period of time to prevent the ram from impacting the parts inside the cylinder with maximum energy.

[0003] For example, a Chinese invention patent CN103538032B discloses an electric hammer. The electric hammer has a guiding mechanism for guiding the striker rod. When the striker rod impacts forward, the guiding length shortens, which can cause the striker rod to tilt relative to the working axis. This slight tilt results in energy consumption to prevent the striker rod from quickly impacting the ram backward and taking the ram out of the locking portion when idling, avoiding repeated impacts (idle hammering) of the ram when the electric hammer is idling and improving the service life of the electric hammer. However, in this solution, in order to cause the striker rod to tilt, there needs to be a sufficient gap between the striker rod and the supporting portion that supports the striker rod. This gap causes the striker rod to also have a slight tilt when impacting forward, resulting in low energy transfer efficiency when the ram impacts the tilted striker rod.

[0004] In view of this, it is indeed necessary to provide an improved power tool to overcome the deficiencies of the prior art. [Summary of the Invention]

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a power tool with good anti-idle hammer effect and capable of avoiding energy loss during impact output.

[0006] The technical solution adopted by the present invention to solve the problems of the prior art is: a power tool, including a housing, a motor, a transmission mechanism, and an impact mechanism received within the housing. The impact mechanism includes a cylinder and a striker rod, a guiding device, a ram, and a piston provided within the cylinder. The piston compresses air and drives the ram to impact the striker rod. The guiding device includes a first guiding portion and a second guiding portion located behind the first guiding portion. The striker rod has a first section that slides along the first guiding portion, and a second section and a third section that slide along the second guiding portion. The radial dimension of the third section is smaller than that of the second section;

[0007] When the striker rod moves in the output direction, the second guiding portion sequentially supports the second section and the third section. And before the striker rod is impacted, the second guiding portion supports the second section. At this time, the axis line of the striker rod coincides with the axis line of the cylinder;

[0008] When the impact rod moves in the direction opposite to the output direction, the second guiding portion sequentially supports the third section and the second section to move the impact rod after tilting it with respect to the axis line of the cylinder.

[0009] A further improvement is that the included angle between the impact rod and the axis line of the cylinder is 0.2 - 0.5°.

[0010] A further improvement is that the radial dimension of the first section is equal to the radial dimension of the second section.

[0011] A further improvement is that the impact rod further includes a connecting section connecting the first section and the second section, the radial dimension of the connecting section is larger than that of the first section and the second section, and the connecting section defines the impact rod between the first guiding portion and the second guiding portion.

[0012] A further improvement is that the first guiding portion is a first stepped portion protruding radially inwards along the cylinder, and the first stepped portion is integrally formed with the cylinder; the first section penetrates through the first stepped portion and extends forward.

[0013] A further improvement is that the impact mechanism further includes a sleeve axially limited within the cylinder and located behind the first stepped portion, and the second guiding portion is a second stepped portion protruding radially inwards along the sleeve.

[0014] A further improvement is that the impact mechanism further includes a stop ring disposed between the first guiding portion and the connecting section. When the impact rod moves forward, the first section penetrates through the stop ring and the connecting section abuts against the stop ring; when the impact rod moves backward, the connecting section abuts against the sleeve.

[0015] A further improvement is that the impact mechanism further includes a sliding ring located between the stop ring and the sleeve, and the stop ring and the sliding ring are relatively slidably limited between the first guiding portion and the second guiding portion.

[0016] A further improvement is that a flange portion protrudes radially outwards from the end of the rammer facing the impact rod, and the impact mechanism further includes a locking portion limited within the cylinder and engaged with the flange portion. When the power tool is in an idle state, the flange portion is engaged within the locking portion.

[0017] A further improvement is that a third stepped surface protrudes radially inwards from the inner wall of the cylinder, the front side of the sleeve abuts against the third stepped surface, and the rear side of the sleeve abuts against the locking portion.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] When the striking rod moves in the direction opposite to the output direction, the second guiding part supports the third section and the second section in sequence. The diameter of the third section is smaller than that of the second section. By increasing the gap between the second guiding part and the third section, the striking rod is tilted relative to the axis line of the cylinder and then moves. When the power tool is idling, this tilt consumes the energy of the reversely moving striking rod to prevent the striking rod from taking the hammer away from the locking part, preventing the hammer from striking when idling and thus affecting the service life of the power tool. When the power tool is under load, this tilt also consumes the energy of the striking rod to reduce the recoil force of the striking rod on the power tool. Before the striking rod is impacted, the second guiding part supports the second section. At this time, the axis line of the striking rod coincides with the axis line of the cylinder, the hammer impacts the striking rod in a straight line direction, and the striking rod outputs the impact in a straight line direction, increasing the energy transfer efficiency. [Description of the Drawings]

[0020] The following further describes in detail the specific embodiments of the present invention with reference to the drawings:

[0021] Figure 1 is a three-dimensional schematic diagram of a power tool according to a preferred embodiment of the present invention;

[0022] Figure 2 is Figure 1 a sectional view of the power tool shown;

[0023] Figure 3 is Figure 1 a partially enlarged schematic diagram of the working state of the power tool shown;

[0024] Figure 4 is Figure 1 a partially enlarged schematic diagram of the hammer-locking state of the power tool shown

[0025] Figure 5 is Figure 1 a three-dimensional schematic diagram of the striking rod of the power tool shown;

[0026] The meanings of the reference numerals in the drawings:

[0027] Power tool 100, housing 10

[0028] Motor 20, motor shaft 21

[0029] Transmission mechanism 30, gear 31

[0030] Eccentric wheel 32, eccentric pin 33

[0031] Impact mechanism 40, cylinder 41

[0032] Third step surface 411, connecting rod 42

[0033] Piston 43, hammer 44

[0034] Flange 441 Strike rod 45

[0035] First section 451 Second section 452

[0036] Third section 453 connecting section 454

[0037] Inclined surface 455 Sleeve 46

[0038] Protrusion 461 Buffer ring 462

[0039] Stop ring 47 Sliding ring 48

[0040] Locking part 49 O-ring 491

[0041] Guide device 50 First guide portion 51

[0042] Second guide 52 Clamp 60 [Specific implementation method]

[0043] 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 words "upper", "lower", "front", "back", etc., which indicate the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0044] See also Figures 1 to 5 The figure shows an electric tool 100 involved in a preferred embodiment of the present invention. In this embodiment, the electric tool 100 is an electric hammer for drilling or chiseling on walls, cement floors, etc., and the output direction of the electric tool 100 is defined as the front. The electric tool 100 shown includes a housing 10, a motor 20 disposed in the housing 10, a transmission mechanism 30, an impact mechanism 40, a chuck 60 extending outward from the front end of the housing 10, and a working head (not shown) held in the chuck 60. After the electric tool 100 is started, the motor 20 drives the impact mechanism 40 to perform impact input via the transmission mechanism 30, and the impact assembly 40 drives the working head in the chuck 60 to perform impact output.

[0045] See also Figures 2 to 4 As shown, the motor 20 includes a motor shaft 21 extending axially perpendicular to the output direction, and the transmission mechanism 30 includes a gear 31 meshing with the motor shaft 21, an eccentric wheel 32 transmission-connected to the gear 31, and an eccentric pin 33 integrally provided with the eccentric wheel 32. The motor shaft 21 drives the eccentric wheel 32 to rotate through the gear 31.

[0046] The impact mechanism 40 includes a cylinder 41 and a striker 45, a guiding device 50, a stop ring 47, a sliding ring 48, a sleeve 46, a buffer ring 462, a locking portion 49, a hammer 44, a piston 43, and a connecting rod 42 that are sequentially arranged in the cylinder 41 from front to back. The rear end of the connecting rod 42 is sleeved on the eccentric pin 33, and the front end is pivotally connected to the piston 43; the eccentric wheel 32 drives the piston 43 to reciprocate through the connecting rod 42. When the piston 42 reciprocates, compressed air drives the hammer 44 to impact the striker 45, and after being impacted, the striker 45 impacts the working head along the output direction.

[0047] Please refer to Figures 3 to 4 As shown, a flange portion 441 protrudes radially outward from the end of the hammer 44 facing the striker 45. The impact mechanism 40 further includes a locking portion 49 that is limited in the cylinder 41 and engages with the flange portion 441. An O-ring 491 for locking the hammer is provided in the locking portion 49. When the power tool 100 is in an idle state and the working head does not contact the workpiece to be processed, the hammer 44 impacts the striker 45 along the output direction, and the striker 45 pushes the working head to the forefront of the chuck 60. At this time, the flange portion 441 of the hammer 44 will pass through the O-ring 491 and move in front of the O-ring 491, and the flange portion 441 is engaged within the O-ring 491, thereby preventing the piston 43 from continuously driving the hammer 44 in the idle state.

[0048] When the power tool 100 is idle, when the force of the striker 45 rebounding after impacting the stop ring 47 is relatively large, the striker 45 impacts the hammer 44 held within the O-ring 491 in the reverse direction, and the hammer 44 is likely to disengage from the O-ring 491 and still perform repeated impacts, thereby affecting the service life of the power tool 100.

[0049] Please refer to Figures 2 to 4 As shown, the guiding device 50 includes a first guiding portion 51 and a second guiding portion 52 located behind the first guiding portion 51. The first guiding portion 51 is a first stepped portion that protrudes radially inward along the cylinder 41, and this first stepped portion is integrally formed with the cylinder 41. The second guiding portion 52 is a second stepped portion that protrudes radially inward along the sleeve 46. The front side of the sleeve 46 abuts against a third stepped surface 411 that protrudes radially inward of the cylinder 41. The outer periphery of the sleeve 46 near its rear end has a protruding portion 461 that protrudes radially outward, and this protruding portion 461 abuts against the locking portion 49 through the buffer ring 462.

[0050] Please refer to Figures 3 to 5As shown, the striker 45 has a first section 451 that slides along the first guiding portion 51, a second section 452 and a third section 453 that slide along the second guiding portion 52. The first section 451 penetrates through the first step portion and extends forward. The radial dimension of the third section 453 is smaller than that of the second section 452; the radial dimension of the first section 451 is equal to that of the second section 452. When the striker 45 moves in the output direction, the second guiding portion 52 successively supports the second section 452 and the third section 453. That is, before the striker 45 is impacted, the second guiding portion 52 supports the second section 452. At this time, the axis line of the striker 45 coincides with the axis line of the cylinder 41. The rammer 44 impacts the striker 45 in a straight line direction, and the striker 45 performs impact output in a straight line direction, increasing the energy transfer efficiency; when the striker 45 moves in the direction opposite to the output direction, the second guiding portion 52 successively supports the third section 453 and the second section 452 to move the striker 45 after tilting it relative to the axis line of the cylinder 41. The included angle of the striker 45 tilted relative to the axis line of the cylinder 41 is between 0.2° and 0.5°. When the power tool 100 is idling, the tilt of the striker 45 consumes the energy of the striker 45 moving in the reverse direction to prevent the striker 45 from taking the rammer 44 away from the O-ring 491, so as to improve the service life of the power tool 100; when the power tool 100 is under load, this tilt also consumes the energy of the striker 45 to reduce the recoil force of the striker 45 on the power tool 100.

[0051] An inclined surface 455 is formed between the second section 452 and the third section 453. When the striker 45 moves backward, the inclined surface 455 impacts the side wall of the second guiding portion 52 to reduce vibration and noise.

[0052] The striker 45 further includes a connecting section 454 that connects the first section 451 and the second section 452. The radial dimension of the connecting section 454 is larger than that of the first section 452 and the second section 452. The connecting section 454 confines the striker 45 between the first guiding portion 51 and the second guiding portion 52. The stop ring 47 is arranged between the first guiding portion 51 and the connecting section 454. When the striker 45 moves forward, the first section 451 penetrates through the stop ring 47 and the connecting section 454 abuts against the stop ring 47; when the striker 45 moves backward, the connecting section 454 abuts against the sleeve 46 to achieve axial limit of the striker 45.

[0053] The sliding ring 48 is arranged between the stop ring 47 and the sleeve 46. The sliding ring 48 and the stop ring 47 are relatively slidably limited between the first guiding portion 51 and the second guiding portion 52. When the power tool 100 performs an upward striking operation, the sliding ring 48 prevents the stop ring 47 from directly falling onto the striker 45 and thus affecting the output; in addition, the sliding ring 48 and the stop ring 47 have a certain sliding distance in the axial direction to buffer the forward impact force of the striker 45 during idling, which is beneficial to preventing the stop ring 47 from being impacted and broken.

[0054] In this embodiment, when the striking rod 45 moves in the direction opposite to the output direction, the second guiding portion 52 sequentially supports the third section 453 and the second section 452. The diameter of the third section 453 is smaller than that of the second section 452. By increasing the gap between the second guiding portion 52 and the third section 453, the striking rod 45 is tilted relative to the axis line of the cylinder 41 and then moves. When the power tool 100 is idling, this tilt consumes the energy of the striking rod 45 moving in the reverse direction to prevent the striking rod 45 from taking the hammer 44 away from the locking portion 49, and to prevent the hammer 44 from impacting when idling, thereby affecting the service life of the power tool 100. When the power tool 100 is under load, this tilt also consumes the energy of the striking rod 45 to reduce the recoil force of the striking rod 45 on the power tool 100. Before the striking rod 45 is impacted, the second guiding portion 52 supports the second section 452. At this time, the axis line of the striking rod 45 coincides with the axis line of the cylinder 41, the hammer 44 impacts the striking rod 45 in a straight line direction, and the striking rod 45 outputs an impact in a straight line direction, increasing the energy transfer efficiency.

[0055] The present invention is not limited to the above specific embodiments. It can be easily understood by those of ordinary skill in the art that, without departing from the principles and scope of the present invention, there are many alternative solutions for the power tool of the present invention. The protection scope of the present invention is subject to the content of the claims.

Claims

1. An electric tool, comprising a housing, a motor, a transmission mechanism and an impact mechanism received in the housing. The impact mechanism includes a cylinder, a striker, a guiding device, a hammer and a piston disposed in the cylinder. The piston compresses air and drives the hammer to impact the striker. It is characterized in that: The guiding device includes a first guiding portion and a second guiding portion located behind the first guiding portion. The striker has a first section that slides along the first guiding portion, and second and third sections that slide along the second guiding portion. The radial dimension of the third section is smaller than that of the second section. When the striker moves in the output direction, the second guiding portion sequentially supports the second and third sections. And before the striker is impacted, the second guiding portion supports the second section, and at this time, the axis line of the striker coincides with the axis line of the cylinder. When the striker moves in the direction opposite to the output direction, the second guiding portion sequentially supports the third and second sections to tilt the striker relative to the axis line of the cylinder and then move it.

2. The electric tool according to claim 1, wherein: The included angle at which the striker is tilted relative to the axis line of the cylinder is between 0.2° and 0.5°.

3. The power tool according to claim 1, characterized in that: The radial dimension of the first section is equal to that of the second section.

4. The power tool according to claim 1, characterized in that: The striker further includes a connecting section connecting the first section and the second section. The radial dimension of the connecting section is larger than those of the first and second sections. The connecting section defines the striker between the first guiding portion and the second guiding portion.

5. The power tool according to claim 4, characterized in that: The first guiding portion is a first stepped portion protruding radially inward along the cylinder. The first stepped portion is integrally formed with the cylinder. The first section penetrates through the first stepped portion and extends forward.

6. The power tool according to claim 5, characterized in that: The impact mechanism further includes a sleeve axially limited within the cylinder and located behind the first stepped portion. The second guiding portion is a second stepped portion protruding radially inward along the sleeve.

7. The power tool according to claim 6, characterized in that: The impact mechanism further includes a stop ring disposed between the first guiding portion and the connecting section. When the striker moves forward, the first section penetrates through the stop ring and the connecting section abuts against the stop ring. When the striker moves backward, the connecting section abuts against the sleeve.

8. The electric tool according to claim 7, characterized in that: The impact mechanism further includes a sliding ring located between the stop ring and the sleeve. The relative sliding of the stop ring and the sliding ring is limited between the first guiding portion and the second guiding portion.

9. The power tool according to claim 6, characterized in that: The end of the hammer facing the striker protrudes radially outward with a flange portion. The impact mechanism further includes a locking portion limited within the cylinder and engaging with the flange portion. When the power tool is in an idle state, the flange portion is engaged within the locking portion.

10. The power tool according to claim 9, characterized in that: The inner wall of the cylinder protrudes radially inward with a third stepped surface. The front side of the sleeve abuts against the third stepped surface, and the rear side of the sleeve abuts against the locking portion.

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