CN201253841Y - Hammer drill - Google Patents

Abstract

The utility model discloses a hammer drill, comprising a shell body, a motor arranged inside the shell body to generate rotating force, an operating tool, an impact force transfer mechanism and a switching mechanism; wherein, the impact force transfer mechanism comprises a gas cylinder, a piston, a motion conversion mechanism and a mobile element; the gas cylinder can be rotatably supported inside the shell body and is provided with a first end and a second end; the first end and a second end can be axially extended; the operating tool is connected with the first end through a collet; the piston is arranged near the second end inside the gas cylinder and can move axially; the motion conversion mechanism can convert the rotating force of the motor into the reciprocation of the piston; the mobile element is arranged inside the gas cylinder and between the operating tool and the piston and can move axially; an air room is formed in the gas cylinder between the piston and the mobile element; the gas cylinder is provided with at least a through hole for communicating the air room with the fluid outside the gas cylinder; the switching mechanism switches the operating mode between a first operating mode and a second operating mode; and the switching mechanism comprises a spacing mechanism which can restrict the displacement of the mobile element. The entire tool is compact in structure and low in manufacturing and assembly costs.

Description

Hammer drill

Technical Field

The utility model relates to a hammer drill, include the impact force transmission mechanism who applies operating tool with the impact force and transmit operating tool's revolving force transmission mechanism with the revolving force.

Background

Currently, hammer drill tools on the market have four modes of operation, depending on the application: a hammer drill mode in which an impact force is applied to the operating tool while the operating tool is driven to rotate; a single drill mode in which only the operating tool is driven to rotate; a single hammer mode in which an impact force is applied to only the operating tool; and a hammer angle mode in which the transmission of the rotational force to the operating tool is mechanically interrupted. The switching of these modes is typically accomplished by a different operating mode switching mechanism.

In U.S. Pat. No. 6,116,352, a hammer drill is disclosed, in which a set of control vents and a set of auxiliary vents are provided at intervals on a cylinder, a control member fixed to a housing is provided around the cylinder, and the cylinder itself is axially reciprocated relative to the housing, so that the control vents are covered or uncovered by the control member. If the operating tool with steps is installed on the electric hammer chuck, the impact block cannot cover the auxiliary air holes, a closed air chamber cannot be formed in the air cylinder, and at the moment, the operating tool cannot execute hammering reciprocating motion. If the operating tool installed on the electric hammer chuck does not have a step, the impact element can be directly pushed to move towards the piston, the impact block can be pushed and the auxiliary air holes are sealed, so that an air spring is formed in the cylinder, and the impact force transmitted by the impact force transmission mechanism of the electric hammer can be transmitted to the operating tool through the piston and the air spring. The hammer drill can control the opening and closing of the hammering function without a separate switching mechanism, but the shape of an operation tool matched with the hammer drill has specific requirements, and the operation mode of the hammer drill is difficult to control for a common operation tool.

U.S. patent publication No. 2006/0108132a1 discloses a hammer drill, wherein a cylinder is provided with a set of through holes, and a switching mechanism can selectively switch an operation mode between a first mode and a second mode through the relative displacement between the cylinder and a sliding sleeve. In the first operating mode, the through hole is closed when the operating tool is moved toward the one end of the housing, and the reciprocating motion of the cylinder generates a reciprocating motion in the air chamber when the through hole is closed, allowing the impact member to transmit an impact force to the operating tool. In a second mode of operation, the through-hole is constantly open, limiting the transmission of the impact force by the striker to the operating tool. In the function switching mechanism, the sliding sleeve and the air cylinder need good matching, the manufacturing requirement is high, and the corresponding cost is high. Meanwhile, the whole set of switching elements needs to generate relative axial displacement in the operation process, the required space of the whole set of mechanism is large, and the movement of each part in the operation process is complex.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a hammer drill tool with compact structure and low cost is provided.

According to the utility model discloses, a hammer drill, include: a housing; a motor disposed in the housing to generate a rotational force; an operating tool; an impact force transmission mechanism including a cylinder rotatably supported in the housing and having axially extending first and second ends, an operating tool connected to the first end through the collet, a piston disposed in the cylinder adjacent the second end and axially movable, a motion conversion mechanism converting a rotational force of the motor into a reciprocating motion of the piston, and a moving member disposed in the cylinder between the operating tool and the piston and axially movable, an air chamber being formed in the cylinder between the piston and the moving member, the cylinder having at least one through hole providing fluid communication between the air chamber and an outside of the cylinder; the rotating force transmission mechanism comprises a rotating cylinder and a gear for operating the tool; and a switching mechanism that switches the operation mode between a first operation mode in which fluid communication between the through hole and the air chamber is cut off and a second operation mode in which the through hole is held in fluid communication with the air chamber, the switching mechanism including a position restricting mechanism that restricts a displacement amount of the moving element.

The utility model discloses well adoption sets up the stop gear between cylinder outer wall and casing, does not need additionally to occupy the space of instrument, can realize the mode switch to the hammer drill. The whole tool has compact structure and low manufacturing and assembling cost.

According to the utility model discloses, stop gear includes relative cylinder radial movement or relative cylinder pivoted locking element. Therefore, parts matched with the outer wall of the cylinder are reduced, the corresponding matching surface with higher processing requirements does not exist, and the production cost is reduced.

Preferably, the limiting mechanism comprises an annular sleeve sleeved outside the air cylinder, and the annular sleeve drives the locking element to move or rotate between a position close to the moving element and a position far away from the moving element. The switching mechanism can drive the limiting mechanism to function through a function switching button, and an operator can operate the limiting mechanism simply and conveniently.

Preferably, the limiting mechanism further comprises an elastic element arranged between the annular sleeve and the cylinder, so that when the annular sleeve is released, the locking element can automatically return to a position separated from the inner wall of the cylinder under the elastic force of the elastic element. No additional driving force needs to be applied. Preferably, the elastic element is a compression spring.

Preferably, the annular sleeve body is annular, and the inner wall of the annular sleeve body comprises a conical surface and a cylindrical surface, and the locking element can move between the conical surface and the cylindrical surface. The smooth transition between the conical surface and the cylindrical surface can provide space for the locking element to be positioned at different positions and can also provide certain driving force for the locking element to be kept at different positions. Of course, the conical surface may be replaced by a part of a spherical surface, and in the case where the locking element is a steel ball, the spherical surface and the steel ball cooperate to facilitate the movement and positioning of the locking element.

The locking element may also be constructed in a manner other than a steel ball. The locking element includes a top portion having a cylindrical cross-sectional shape and an extension portion having a cross-sectional diameter smaller than the cross-sectional diameter of the top portion. In this way, the extension of small diameter section can project into the inner wall of the cylinder to limit the axial displacement of the mobile element, while the top of large diameter section projects outside the cylinder to cooperate with the switching mechanism.

Preferably, the cross-sectional diameter of the extension portion is gradually reduced from the top in the axial direction. Thus, the extension can be moved relatively easily from the bore in the cylinder.

Preferably, one end of the top part, which is adjacent to the extending part, is provided with a groove, and the elastic piece is accommodated in the groove. Thereby, an automatically resetting connection is established between the locking element and the annular sleeve.

Preferably, the length of the extension part extending into the cylinder is larger than the distance between the outer wall of the moving element and the inner wall of the cylinder.

According to an aspect of the invention, the moving element is a collet sleeve for receiving the operating tool. The chuck sleeve comprises a front end for receiving an operating tool and a rear end accommodated in the cylinder, the sliding groove is radially arranged from the outer wall and axially extends, the rolling body is arranged between the cylinder and the chuck sleeve and accommodated in the sliding groove, and the chuck sleeve moves between one end, located at the front end of the chuck sleeve, of the sliding groove and the other end, located at the front end of the chuck sleeve, of the rolling body and the other end, located at the sliding groove, of the rolling body, of the chuck sleeve relative to the cylinder. The cylinder is provided with holes axially spaced from the through holes, and the axial positions of the holes are located in front of the rear end of the chuck sleeve when the rolling bodies are located at one end, adjacent to the front end of the chuck sleeve, of the sliding groove.

According to another aspect of the invention, the moving element is a punch in direct contact with the operating tool. The drift includes the front end with the operating tool contact and accepts the rear end in the cylinder, and the spout radially sets up and axial extension from the outer wall, the cylinder with set up between the drift roller accept in the spout, the drift moves between the one end that the roller is located the spout and is close to the drift front end and the other end that the rolling element is located the spout and keeps away from the drift front end relative to the cylinder. The cylinder is provided with holes axially spaced from the through hole, and the axial positions of the holes are located in front of the rear end of the punch when the rolling piece is located at one end, adjacent to the front end of the punch, of the sliding groove.

According to another aspect of the invention, the moving element is an impact block with a ring groove. Preferably, the annular sleeve comprises first and second axially extending annular portions, the first annular portion having an outer diameter greater than the second annular portion, the annular portions having the same inner diameter. In this way, the portion between the first and second annular portions provides sufficient space for rotation of the locking element when the locking element is pivoted relative to the cylinder.

Preferably, the switching mechanism comprises a control knob having an eccentric pin which drives the limit mechanism to move between a position which limits the amount of axial displacement of the moving element and a position which releases the amount of axial displacement of the moving element. The control knob further includes a cam that drives the switching member to move between a position that turns on transmission of the rotational force and a position that turns off transmission of the rotational force. The cam also drives the switching element to move between a position that limits the rotation of the cylinder and a position that allows the cylinder to rotate. Therefore, through the function switching knob, the hammer drill tool can be easily switched to different working modes, and the operation is simple and convenient.

Drawings

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Fig. 1 is a partially sectional schematic view of a hammer drill according to a first embodiment of the present invention.

Fig. 2 is a partial cross-sectional view of the hammer drill taken along line a-a of fig. 1, with the hammer drill in an impact force transmitting open state.

Fig. 3 is a partial cross-sectional view of the hammer drill taken along line a-a of fig. 1, with the hammer drill in an impact force transmission off state.

Fig. 4 is a partial cross-sectional view of the hammer drill according to the first embodiment of the present invention, at this time, the hammer drill is in a rotational force transmitting open state;

fig. 5 is a partial cross-sectional view of the hammer drill according to the first embodiment of the present invention, at this time, the hammer drill is in a rotational force transmission off state;

fig. 6 is a partial cross-sectional view of the hammer drill according to the first embodiment of the present invention, when the hammer drill is in the cylinder rotation lock open state;

fig. 7 is a partial cross-sectional view of the hammer drill according to the first embodiment of the present invention, when the hammer drill is in a cylinder rotation lock off state;

fig. 8 is a schematic view of the cam and the eccentric pin of the adjusting knob in the switching mechanism of the hammer drill according to the first embodiment of the present invention in different operating positions;

fig. 9 is a partially schematic cross-sectional view of a hammer drill according to a second embodiment of the present invention.

Fig. 10 is a partial cross-sectional view of the hammer drill taken along the line B-B in fig. 9, with the hammer drill in an impact force transmitting open state.

Fig. 11 is a partial cross-sectional view of the hammer drill taken along the line B-B in fig. 9, with the hammer drill in an impact force transmission off state.

Fig. 12 is a partially schematic cross-sectional view of a hammer drill according to a third embodiment of the present invention.

Fig. 13 is a partial cross-sectional view of the hammer drill taken along the line C-C in fig. 12, with the hammer drill in an impact force transmitting open state.

Fig. 14 is a partial cross-sectional view of the hammer drill taken along the line C-C in fig. 12, with the hammer drill in an impact force transmission off state.

Fig. 15 is a partial cross-sectional view of the hammer drill taken along line D-D in fig. 14.

Wherein,

1, 1A, 1B hammer drill 2 casing 2A motor casing

2B cylinder shell 4 handle 6 switch

8 cable 10, 10A, 10B switching mechanism 12 knob

14 eccentric pin 16 cam 18 machine shell internal tooth

19 rib 20 switching element 21 elastomer

22 external teeth 24 internal spline 26 auxiliary handle

28 operating tool 30 impact force transmission mechanism 31 and rotational force transmission mechanism

33 motor 34 motor shaft 36 pinion

38 crankshaft 40 first gear 42 crankpin

44 connecting rod 46 piston 48 gudgeon pin

50 cylinder 51 longitudinal axis 52 through hole

53 protruding 54 air chamber 55 sealing ring

56, 56A impact block 57 ring groove 58 intermediate shaft

60 second gear 62 bevel gear 64 bevel gear

66 external spline 68 torsion trip mechanism 70 first clutch element

72 outer teeth 74 inner end teeth 76 second clutch element

78 outer end teeth 80 and inner teeth 82 first elastic element

84 retainer ring 86 bearing 88 intermediate part

90 punch 92 chute 94 roller

96 collet 98 collet sleeve 100 chute

101 rolling body 102 steel ball 104 elastic element

106, 108, 208, 308, and 110, 210, 310, annular sleeves

114, 214, 115, 215, 116, 216, 316, elastic element

118, 218, 318 locking element 119, 219, 319 aperture 120, 220, 320 stop

224 top 226 extension 228 spring

230 groove 312 first annular portion 314 second annular portion

322 pin 324 torsion spring 326 first stop

328 second stop 330 thrust receiving portion

Detailed Description

First embodiment

Referring to fig. 1 to 8 below, a hammer drill 1 according to a first embodiment of the present invention includes a housing 2, a motor 33, an operating tool 28, an impact force transmission mechanism 30, a rotational force transmission mechanism 31, a switching mechanism 10, and the like. The hammer drill 1 can be operated in a rotation and impact mode (hammer drill), an impact only mode (hammer), a rotation only mode (drill), and an intermediate mode (hammer angle).

The hammer drill 1 includes a handle 4 provided on the rear end of the housing 2, a switch 6 provided on the handle 4, a cable 8 connected to the handle 4 for supplying electric power to the hammer drill 1, a switching mechanism 10 rotatably provided on the housing 2 for switching an operation mode, and an auxiliary handle 26 provided near the front end of the housing 2. The operating tool 28 is mounted on the front end of the hammer drill 1 via the collet 96. The operation tool 28 receives the impact force and the rotational force transmitted from the motor 33, and performs different machining operations on the workpiece.

The housing 2 includes a motor housing 2A and a cylinder housing 2B. The motor housing 2A accommodates a motor 33 as a power source of the hammer drill. The motor 33 is provided with a motor shaft 34, and a pinion 36 is formed integrally with the motor shaft 34. The cylinder 50 extends along its longitudinal axis 51, is received in the cylinder housing 2B, and is rotatable relative to the cylinder housing 2B about its longitudinal axis 51.

The impact force transmission mechanism 30 includes a crank shaft 38, a first gear 40, a connecting rod 44, a cylinder 50, a piston 46, an impact block 56, an intermediate member 88, and the like, and converts the rotational force of the motor 33 into the reciprocating motion of the piston 46.

An impact block 56 is disposed in the cylinder between the operating tool 28 and the piston 46 and is axially slidable.

The intermediate member 88 includes a punch 90. The punch 90 is located between the operating tool 28 and the piston 46 and has a radially extending slot 92 in the outer wall thereof, and a ball 94 is received in the slot 92. The punch 90 is axially movable relative to the cylinder 50 by the connection of the steel ball 94 with the slide slot 92.

The crank shaft 38 is disposed in parallel to the motor shaft 34. The first gear 40 is fitted over the crank shaft 38 to be engaged with the motor pinion 36, and transmits the rotation of the motor 33 to the crank shaft 38, thereby being converted into an axial reciprocating motion of a piston 46 connected to the connecting rod 44 through a piston pin 48 by a crank pin 42 eccentrically provided at the top of the crank shaft 38 and a connecting rod 44 fitted over the crank pin 42.

An air chamber 54 is formed in the cylinder 50 between the piston 46 and an impact block 56. At least one through hole 52 communicates with the air chamber 54. The number of the through holes in this embodiment is 1. It may be designed to be 2, 3 or 4 evenly distributed along the circumferential direction of the cylinder 50 as needed. Fluid communication between the cylinder 50 and the air chamber 54 is controlled by opening or closing of the through-hole 52. When the through hole 52 is opened, the air pressure in the air chamber 54 matches the air pressure outside the cylinder 50, and the reciprocating movement of the piston 46 in the cylinder 50 does not cause the impact block 56 to reciprocate. When the through-hole 52 is closed, the pressure in the air chamber 54 changes with the reciprocating movement of the piston 46, thereby moving the impact block 56. The air chamber 54 acts here as a gas spring, powering the reciprocating movement of the impact block 56.

The cylinder 50 is rotatably supported in the cylinder housing 2B by bearings 86 and 87, having first and second ends extending along its longitudinal axis 51.

The piston 46 is disposed in the cylinder 50 adjacent the second end and is axially reciprocable within the cylinder 50 relative to the cylinder 50.

The collet 96 includes a collet sleeve 98 partially received in the cylinder 50, a collet sleeve 106 disposed about the collet sleeve 98, and a resilient member 104 disposed between a front wall of the cylinder 50 and the collet sleeve 106. The front end of the chuck sleeve 98 is provided with a plurality of radially and uniformly distributed through holes, and the steel balls 102 are accommodated in the through holes and used for locking the operating tool 28. The outer wall of the chuck sleeve 98 extends axially to form a sliding slot 100, the front end of the cylinder 50 is provided with a plurality of radially and uniformly distributed through holes at the part matched with the chuck sleeve 98, and the steel balls 94 are accommodated in the through holes and can limit the chuck sleeve 98 to move on the axial length of the sliding slot 100. The operating element 28 is connected to a first end of the cylinder 50 by a collet 96.

The rotational force transmission mechanism 31 includes an intermediate shaft 58, a second gear 60, bevel gears 62 and 64, clutch elements 70, 76, and a cylinder 50, etc. The intermediate shaft 58 is disposed perpendicular to the longitudinal axis 51 of the cylinder 50 and is rotatably supported in the cylinder housing 2B on the other side of the motor shaft 34 from the crank shaft 38, i.e., the crank shaft 38 and the intermediate shaft 58 are parallel to each other and disposed on different sides of the motor shaft 34, respectively. A second gear 60 is fixedly attached to the intermediate shaft 58 and is in meshing engagement with the motor pinion 36. The bevel gear 62 is arranged at one end of the intermediate shaft 58 and is meshed with a bevel gear 64 sleeved outside the air cylinder 50. The axes of bevel gear 62 and bevel gear 64 are perpendicular to each other. The internal teeth 80 of the second clutch member 76 are engaged with the protrusions 53 provided on the outer wall of the cylinder 50, the first clutch member 70 and the second clutch member 76 are engaged with each other by the internal end teeth 74 and the external end teeth 78, and the first clutch member 70 is engaged with the bevel gear 64 by the switching mechanism 10 to rotate the cylinder 50, thereby transmitting the rotational driving force transmitted from the motor shaft 34 to the cylinder 50.

The switching mechanism 10 includes a through hole 52, a limit mechanism 108, a switching element 20, a control knob 12, a rotation lock mechanism 18, and the like. The control knob 12 includes a cam 16 and an eccentric pin 14. The control knob 12 is used to turn on and off the transmission of impact force to the operating tool 28 and turn on and off the transmission of rotational force to the operating tool 28, thereby switching the operating mode between a rotation and impact mode (hammer drill), an impact-only mode (hammer), and a rotation-only mode (drill).

In this embodiment, the limit mechanism 108 limits the axial displacement of the collet sleeve 98.

The collet sleeve 98 includes a front end for receiving the operating tool 28 and a rear end received in the cylinder 50, a slide slot 100 radially disposed from the outer wall and extending axially, rolling elements 101 disposed between the cylinder 50 and the collet sleeve 98 are received in the slide slot 100, and the collet sleeve 98 is movable relative to the cylinder 50 between an end of the rolling elements 101 located in the slide slot 100 adjacent the front end of the collet sleeve 98 and an end of the rolling elements 101 located in the slide slot 100 distal from the front end of the collet sleeve 98. The amount of axial displacement of the collet sleeve 98 is S1, determined by the axial length of the slide slot 100. The cylinder 50 is provided with a bore 119 axially spaced from the through bore 52, the bore 119 being axially located before the rear end of the collet sleeve 98 when the rolling bodies 101 are located at the end of the runner 100 adjacent the front end of the collet sleeve 98.

The spacing mechanism 108 includes an annular sleeve 110, a locking element 118, a resilient element 116, and a stop 120. The cylinder 50 is radially perforated with a plurality of uniformly spaced holes 119 adjacent the end of the collet sleeve 98, and the locking elements 118, here steel balls, are received in the holes 119. The resilient element 116 is a compression spring with one end abutting the bearing 86 and the other end abutting an end face of the annular sleeve 110. The annular sleeve 110 is a ring-shaped body whose inner wall includes a tapered surface 114 and a cylindrical surface 115. Where cylindrical surface 115 is smoothly connected to tapered surface 114, locking element 118 can move between the two surfaces without requiring a significant amount of force. Of course, the conical surface can also be replaced by a partial spherical surface, and in the case that the locking element is a steel ball, the spherical surface and the steel ball are matched to be more beneficial to moving and positioning the locking element.

Normally, the elastic element 116 exerts an elastic force to make the annular sleeve 110 abut against the stop 120, and the spherical surface of the steel ball engages with the inner conical surface/partial spherical surface 114 of the annular sleeve 110. At this time, all the steel balls are located in the wall of the cylinder 50, and the collet sleeve 98 is freely axially movable in the cylinder 50 to the maximum displacement S1. The impact block 56 is able to pass through the through bore 52 and the axial movement of the impact block 56 is sufficient to cause the axial movement of the piston 46 to produce a pressure change within the air chamber 54, effecting an impact to the punch 90 and the working tool 28.

When the annular sleeve 110 is pushed by the eccentric pin 14 and moves in the opposite direction against the elastic force of the elastic element 116, the steel ball disengages from the inner conical surface/partial spherical surface 114 of the annular sleeve 110 and is pressed by the inner cylindrical surface 115 of the annular sleeve 110 toward the smaller diameter end of the bore 119, i.e., the locking element 118 moves radially relative to the cylinder 50, so that the partial spherical surface of the steel ball exceeds the inner wall of the cylinder 50 and limits the amount of displacement of the collet sleeve 98 in the axial direction toward the piston 46, and the collet sleeve 98 cannot move to the maximum displacement S1, and the punch 90 cannot contact the impact block 56. Thus, even in the operating state of the impact force transmission mechanism 30, since the collet sleeve 98 cannot achieve a sufficient axial displacement S1, the impact block 56 cannot pass through the through hole 52, and the air chamber 54 cannot be closed, so that a pressure change is generated and an impact is realized.

The switching element 20 includes external teeth 22 provided on its outer surface and internal splines 24 provided on its inner surface. The switching element 20 is movable by the cam 16 along the axis 51 of the cylinder 50 to different operating positions, selectively engaging or disengaging the housing internal teeth 18, and selectively engaging or disengaging the first clutch element 70 and the bevel gear 64. When the switching member 20 is in the position shown in fig. 1, its outer teeth 22 mesh with the housing inner teeth 18, its inner splines 24 mesh with the outer teeth 72 of the first clutch member 70, the inner end teeth 74 of the first clutch member 70 mesh with the outer end teeth 78 of the second clutch member 76, and the inner teeth 80 of the second clutch member 76 mesh with the projections 53 on the cylinder 50. At this time, the bevel gear 64 idles against the cylinder 50, and the cylinder 50 is fixed to the cylinder housing 2B. An elastic body 21 is disposed between the switching member 20 and the housing 2 to provide an elastic restoring force for the movement of the switching member 20. The elastic body 21 is here a compression spring, one end of which abuts against an end face of the switching element 20 and the other end of which abuts against the housing 2. The cylinder housing 2B is provided with a rib plate 19 inside for abutting against the elastic body 21.

The housing internal teeth 18 are a rotation locking mechanism that is engaged with or disengaged from the cylinder 50 by the movement of the switching member 20, thereby locking and unlocking the rotation of the cylinder 50.

The torsional trip mechanism 68 includes a first clutching element 70, a second clutching element 76, and a first resilient element 82. The first clutch member 70 is axially movably disposed outside the cylinder 50 and has radially disposed outer teeth 72 and axially disposed inner end teeth 74. The second clutch member 76 is also disposed outside the cylinder 50 and has an outer diameter less than the diameter of the internal recess of the first clutch member 70, with outer end teeth 78 and internal teeth 80. The first elastic element 82 is a spring, and is disposed outside the cylinder 50, and has one end abutting against an end surface of the first clutch element 70 and the other end abutting against a retainer ring 84 fixed outside the cylinder 50. The first spring element 82 always presses the first clutch element 70 against the second clutch element 76. When the rotational force transmission mechanism 31 is operated, the bevel gear 64 is connected to the first clutch element 70 via the switching element 20, and the motor 33 transmits the rotational force to the bevel gear 64, and thus to the cylinder 50 and the operating tool 28. When the torque load experienced by the operating tool 28 exceeds a certain value, the inner end teeth 74 and the outer end teeth 78 of the first clutch element 70 and the second clutch element 76 are disengaged. At this time, although the first clutch member 70 and the bevel gear 64 are connected to each other, the cylinder 50 is subjected to an excessive load and stops rotating, and the second clutch member 76 connected to the cylinder 50 also stops rotating, so that the first clutch member 70 is axially moved against the elastic force of the first elastic member 82 and slips between the inner end teeth 74 and the outer end teeth 78. The motor 33 still drives the bevel gear 64 to rotate, but the air cylinder 50 is not driven to rotate any more, and the air cylinder 50 is fixed and cannot influence the rotation of the bevel gear 64, so that the motor 33 cannot be locked up.

Specifically, the switching mechanism 10 switches the operational state of the hammer drill 1 between the functional modes as follows.

Opening/closing of impact force transmission:

the control knob 12 in the switching mechanism 10 is rotated and the annular sleeve 110 is urged at one end against the stop 120 by the resilient force of the resilient member 116 and the locking member 118 is located within the wall of the cylinder 50 out of engagement with the collet sleeve 98. When the working tool 28 is brought into abutment against the workpiece, the reaction force urges the intermediate member 88 rearwardly, and the ram 90 in the intermediate member 88 moves towards the impact block 56 for a maximum stroke, and is able to continue to urge the impact block 56 rearwardly, causing the sealing ring 55 to pass over the through bore 52, thereby forming a sealed air chamber 54 between the impact block 56 and the piston 46. At this time, the fluid communication between the through hole 52 and the air chamber 54 is cut off, and the transmission of the impact force is in an open state.

Rotation of the control knob 12 in the switching mechanism 10 moves the annular sleeve 110 and the locking member 118 against the spring force to axially lock the cylinder 50 and the collet sleeve 98 relative to each other, i.e., the amount of axial displacement of the collet sleeve 98 toward the impact block 56 is limited. When the operating tool 28 is pressed against the workpiece, the reaction force pushes the intermediate member 88 rearward, and the punch 90 in the intermediate member 88 moves toward the impact block 56 for a maximum stroke, and cannot move further relative to the cylinder 50, and thus cannot move the impact block 56 to seal the through hole 52. At this time, fluid communication is maintained between the through-hole 52 and the air chamber 54, and transmission of the impact force is in a closed state.

Opening/closing of rotational force transmission:

the control knob 12 in the switching mechanism 10 is rotated and the cam 16 pushes the switching member 20 to move backward, with its internal splines 24 engaging with the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, and rotates the cylinder 50 together with the bevel gear 64 through the clutch elements 70, 76. At this time, the transmission of the rotational force is in the open state. The control knob 12 in the switching mechanism 10 is rotated and the cam 16 pushes the switching element 20 forward, disengaging its internal splines 24 from the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, but the rotation of the bevel gear 64 is not transmitted to the cylinder 50, and the bevel gear 64 is idly rotated on the cylinder 50. At this time, the transmission of the rotational force is in the closed state.

Cylinder rotation lock on/off:

the control knob 12 in the switching mechanism 10 is rotated, the cam 16 pushes the switching member 20 forward, its outer teeth 22 mesh with the inner teeth 18 of the housing, the clutch members 70, 76 are fixed with respect to the circumferential direction of the housing 2, and thus the cylinder 50 and the housing 2 are fixed with respect to the circumferential direction. At this time, the rotation lock of the cylinder 50 is in the open state. The control knob 12 in the switching mechanism 10 is rotated and the cam 16 pushes the switching member 20 to move backward, and its outer teeth 22 are disengaged from the inner teeth 18 of the housing, so that the clutch members 70, 76 and the cylinder 50 are rotatable circumferentially relative to the housing 2. At this time, the rotation lock of the cylinder 50 is in the off state.

The operation of the hammer drill 1 according to the present invention in different operation modes will be described below.

1) Impact-only mode, i.e. hammer mode

In the hammer mode, the manipulation tool 28 can perform reciprocating impact, but cannot be driven to rotate by the motor 33. That is, the transmission of the impact force of the hammer drill 1 is in the on state, and the transmission of the rotational force is in the off state, and at the same time, the rotational lock of the cylinder is in the on state. The positions of the eccentric pin 14 and the cam 16 in the switching mechanism 10 are shown by the dotted line I in fig. 8. At this time, the switching member 20 is disengaged from the bevel gear 64 and engaged with the housing internal teeth 18, and the locking member 118 is partially dropped into the inner wall of the cylinder 50.

2) Intermediate modes, i.e. hammer angle modes

In the hammer rotation angle mode, the operating tool 28 can perform reciprocating impact, cannot be driven to rotate by the motor 33, and can be actively rotated by the operator. That is, the transmission of the impact force of the hammer drill 1 is in the on state, and the transmission of the rotational force is in the off state, and at the same time, the rotational lock of the cylinder is in the off state. The positions of the eccentric pin 14 and the cam 16 in the switching mechanism 10 are shown as position II in broken lines in fig. 8. The angle of rotation between position I and position II is α 1. At this time, the switching member 20 is disengaged from both the bevel gear 64 and the internal teeth 18 of the housing, and the locking member 118 is partially dropped into the inner wall of the cylinder 50.

3) Rotary and percussive modes, i.e. hammer drill mode

In the hammer drill mode, the hammer drill 1 applies an impact force to the operating tool 28 while driving it to rotate. That is, both the transmission of the impact force and the transmission of the rotational force of the hammer drill 1 are in the on state, and the rotational lock of the cylinder is in the off state. When the switching mechanism 10 is rotated to select the hammer drill operating mode, the positions of the eccentric pin 14 and the cam 16 in the switching mechanism 10 are as shown in solid lines in fig. 8 at position III. The angle of rotation between position II and position III is α 2. At this time, the switching member 20 is engaged with the bevel gear 64 to be disengaged from the internal teeth 18 of the housing, and the locking member 118 is partially dropped into the inner wall of the cylinder 50.

4) Rotary-only mode, i.e. drill mode

In the drill mode, the operating tool 28 is driven to rotate by the motor 33, but cannot perform reciprocating impacts. That is, the transmission of the impact force of the hammer drill 1 is in the closed state, the transmission of the rotational force is all in the open state, and at the same time, the rotational locking of the cylinder is in the closed state. The positions of the eccentric pin 14 and the cam 16 in the switching mechanism 10 are shown as position IV in dashed lines in fig. 8. The angle of rotation between position III and position IV is α 3. At this time, the switching member 20 is engaged with the bevel gear 64 and disengaged from the housing internal teeth 18, and the locking member 118 is located in the wall of the cylinder 50.

Second embodiment

Referring to fig. 9 to 11, a hammer drill 1A according to a second embodiment of the present invention will be described. In the second embodiment, the basic structure of the hammer drill 1A is the same as that of the first embodiment, and therefore, the reference numerals of the corresponding parts are also the same. Only different parts are explained here.

In this embodiment, the limiting mechanism 208 limits the axial displacement of the punch 90.

The punch 90 is in direct contact with the operating tool 28. The punch 90 includes a front end contacting the operating tool 28 and a rear end received in the cylinder 50, a slide groove 92 is radially disposed from an outer wall and axially extends, a roller 94 is disposed between the cylinder 50 and the punch 90 and received in the slide groove 92, and the punch 90 moves relative to the cylinder 50 between an end of the roller 94 located in the slide groove 92 adjacent to the front end of the punch 90 and an end of the roller 94 located in the slide groove 92 away from the front end of the punch 90. The amount of axial displacement of the punch 90 is S2, which is determined by the axial length of the slide groove 92. The cylinder 50 is provided with a bore 219 axially spaced from the through bore 52, the bore 219 being axially located before the rear end of the punch 90 when the roller 94 is located at the end of the chute 92 adjacent the front end of the punch 90.

The spacing mechanism 208 includes an annular sleeve 210, a locking element 218, a resilient element 216, and a stop 220. The cylinder 50 is radially perforated with a plurality of uniformly spaced tapered holes 219 adjacent the end of the ram 90, and the locking elements 218, here steel posts, are partially received in the tapered holes 119. The annular sleeve 210 drives the locking element 218 between a position in which it partially falls within the inner wall of the cylinder 50 and a position away from the inner wall of the cylinder 50. The spacing mechanism 208 further comprises a resilient member 216 disposed between the annular sleeve 210 and the cylinder 50 such that when the annular sleeve 210 is released, the locking member 218 is automatically returned to a position away from within the inner wall of the cylinder 50 by the resilient force of the resilient member 216. Here, the elastic element 216 is a compression spring. The annular sleeve 210 is annular in shape and has an inner wall comprising a tapered surface 214 and a cylindrical surface 215, and the locking element 218 is movable between the tapered surface 214 and the cylindrical surface 215. The smooth transition between the tapered surface 214 and the cylindrical surface 215 provides space for the latching component 218 to be in different positions, and also provides a certain driving force for the latching component 218 to be held in different positions. The locking member 218 includes a top portion 224 having a cylindrical cross-sectional shape and an extension 226, the extension 226 having a cross-sectional diameter smaller than the cross-sectional diameter of the top portion 224. Also, the cross-sectional diameter of the extension 226 is gradually reduced from the top 224 in the axial direction. The top portion 224 has a recess 230 formed at an end thereof adjacent to the extension portion 226, and the resilient member 228 is received in the recess 230. The extension 228 extends into the cylinder 50 a greater length than the distance between the outer wall of the ram 90 and the inner wall of the cylinder 50. In the present embodiment, a collet sleeve 98 is provided between the punch 90 and the cylinder 50, that is, the distance between the outer wall of the punch 90 and the inner wall of the cylinder 50 is the wall thickness of the collet sleeve 98. The locking member 218 is radially movable relative to the cylinder 50 with the extension 226 moving between a position against the rear end of the punch 90 and a position away from the rear end of the punch 90.

In a normal state, the elastic member 216 exerts an elastic force to make the annular sleeve 210 abut against the stopper 220, and the top 224 of the locking member 218 engages with the inner tapered surface 214 of the annular sleeve 210. At this time, a portion of the extension 226 is located within the wall of the cylinder 50 and another portion is located within the inner wall of the cylinder 50, the end of which does not extend beyond the inner wall of the collet sleeve 98, and thus, does not contact the punch 90. The collet sleeve 98 and the punch 90 are both free to move axially within the cylinder 50, the collet sleeve 98 being movable to a maximum displacement S1, and the punch 90 being movable to a maximum displacement S2. At this point, the impact block 56 is able to pass through the through bore 52 and the axial movement of the impact block 56 is sufficient to cause the axial movement of the piston 46 to produce a pressure change within the air chamber 54, effecting an impact against the punch 90 and the working tool 28.

When the annular sleeve 210 is pushed by the eccentric pin 14 and moves in the opposite direction against the elastic force of the elastic member 216, the top 224 of the locking member 218 is disengaged from the inner tapered surface 214 of the annular sleeve 210, and the top 224 of the locking member 218 is radially pressed toward the cylinder 50 by the inner cylindrical surface 215 of the annular sleeve 210, and the extension 226 of the locking member 218 further moves toward the cylinder 50 until the end portion exceeds the inner wall of the collet sleeve 98, and the axial movement of the punch 90 toward the piston 46 is restricted. Thus, even in the state where the impact force transmission mechanism 30 is operated, since the punch 90 cannot achieve a sufficient axial displacement S2, it cannot contact the impact block 56, so that the impact block 56 cannot pass through the through hole 52, and the air chamber 54 cannot be closed, and a pressure change is generated to achieve an impact.

The functional mode switching operation state of the hammer drill 1A with respect to the switching mechanism 10A in the present embodiment is as follows.

Opening/closing of impact force transmission:

the control knob 12 in the switching mechanism 10A is rotated, the annular sleeve 210 and the locking member 218 are partially positioned in the cylinder 50 by the elastic force of the elastic member 216, and the extension 226 of the locking member 218 is disengaged from the collet sleeve 98 and the punch 90. When the working tool 28 is brought into abutment against the workpiece, the reaction force urges the intermediate member 88 rearwardly, and the punch 90 in the intermediate member 88 moves towards the impact block 56 for a maximum stroke S2, which can continue to urge the impact block 56 rearwardly, causing the seal ring 55 to pass over the through bore 52, thereby forming a sealed air chamber 54 between the impact block 56 and the piston 46. At this time, the transmission of the impact force is in the open state. The control knob 12 in the switching mechanism 10A is rotated to move the annular sleeve 210 and the locking member 218 against the spring force to axially lock the cylinder 50 and the punch 90 relative to each other, i.e., the amount of axial displacement of the punch 90 toward the impact block 56 is limited. When the operating tool 28 is abutted against the workpiece, the reaction force pushes the intermediate member 88 to move backward, and the punch 90 in the intermediate member 88 moves toward the impact block 56 without reaching the maximum stroke S2, and cannot move relative to the cylinder 50 to contact the impact block 56, and cannot move the impact block 56 to seal the through hole 52. At this time, the transmission of the impact force is in the off state.

Opening/closing of rotational force transmission:

the control knob 12 in the switching mechanism 10A is rotated and the cam 16 pushes the switching member 20 to move backward, with its internal splines 24 engaging with the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, and rotates the cylinder 50 together with the bevel gear 64 through the clutch elements 70, 76. At this time, the transmission of the rotational force is in the open state. The control knob 12 in the switching mechanism 10A is rotated and the cam 16 pushes the switching member 20 forward, disengaging the internal splines 24 thereof from the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, but the rotation of the bevel gear 64 is not transmitted to the cylinder 50, and the bevel gear 64 is idly rotated on the cylinder 50. At this time, the transmission of the rotational force is in the closed state.

Cylinder rotation lock on/off:

the control knob 12 in the switching mechanism 10A is rotated, the cam 16 pushes the switching member 20 forward, its outer teeth 22 engage with the housing inner teeth 18, and the clutch members 70, 76 are fixed relative to the circumferential direction of the housing 2, so that the cylinder 50 and the housing 2 are fixed relative to each other in the circumferential direction. At this time, the rotation lock of the cylinder 50 is in the open state. The control knob 12 in the switching mechanism 10A is rotated, the cam 16 pushes the switching member 20 to move backward, the outer teeth 22 thereof are disengaged from the inner teeth 18 of the housing, and the clutch members 70, 76 and the cylinder 50 are circumferentially rotatable relative to the housing 2. At this time, the rotation lock of the cylinder 50 is in the off state.

Thus, the hammer drill 1A can be set to the single hammer, the single drill, the hammer drill, and the hammer rotation angle operation mode by the switching mechanism 10A.

Third embodiment

A hammer drill 1B according to a third embodiment of the present invention will be described with reference to fig. 12 to 15. In the third embodiment, the basic structure of the hammer drill 1B is the same as that of the first embodiment, and therefore, the reference numerals of the corresponding parts are also the same. Only different parts are explained here.

The limit mechanism 308 limits the amount of axial displacement of the impact block 56A.

The impact block 56A is received in the cylinder 50 and may axially pass through the through bore 52 to either maintain the through bore 52 in fluid communication with the air chamber 54 or to block fluid communication between the through bore 52 and the air chamber 54. When the through hole 52 is sealed, the impact block 56A reciprocates in the cylinder 50, applying an impact force to the punch 90. The collet sleeve 98 and the punch 90 are axially movable relative to the cylinder 50 by an amount that is dependent on the length of the respective slots in the outer walls thereof. When the collet sleeve 98 and punch 90 move toward the impact block 56A to the maximum strokes S1 and S2, the punch 90 pushes the impact block 56A toward the piston 46, passing through the through hole 52, and hammering is transmitted, and hammering cannot be transmitted if the punch 90 does not push the impact block 56A. In this embodiment, the cylinder 50 is provided with a hole 319 axially spaced from the through hole 52 to receive the stopper mechanism 308. Axial movement of the impact block 56A in the direction of the piston 46 is limited by a limiting mechanism 308.

The impact block 56A is substantially cylindrical and has a ring of circumferential grooves 57 formed in its outer wall. The ring groove 57 has a predetermined axial length.

The limiting mechanism 308 includes an annular sleeve 310, a locking member 318, a resilient member 316, a pivot pin 322, a torsion spring 324, a stop 320, and the like.

A plurality of uniformly distributed holes 319 are radially formed in the position, adjacent to the end of the impact block 56A, of the cylinder 50, and in this embodiment, the number of the holes 319 is one. One skilled in the art can provide different numbers of holes depending on the impact force requirements. The locking member 318 is here a wedge pivotally connected to the cylinder 50 by a pin 322, and a torsion spring 324 is also provided between the cylinder 50 and the locking member 318. Wherein the axis of the pin 322 is perpendicular to but does not intersect the axis of the cylinder 50. The locking element 318 includes a first stop 326, a second stop 328, and a thrust receiver 330. Wherein the first and second stops 326, 328 and the thrust receiver 330 are located on different end surfaces of the locking element 318, respectively, in opposite directions. The locking member 318 is pivotable relative to the cylinder 50 about the pin 322 to be located at a position away from the impact block 56A and a position adjacent to the impact block 56A.

The annular sleeve 310 is disposed over the cylinder 50 and drives the locking member 318 between a position adjacent the impact block 56A and a position away from the impact block 56A. The annular sleeve 310 is annular in shape and includes two axially extending annular portions 312 and 314. The first annular portion 312 has an outer diameter greater than the outer diameter of the second annular portion 314, and the inner diameters of the two annular portions 312 and 314 are the same. In this way, the portion between the first annular portion 312 and the second annular portion 314 provides sufficient space for rotation of the locking element 318 when the locking element 318 pivots relative to the cylinder 50.

The spacing mechanism 308 further includes a resilient member 316 disposed between the annular sleeve 310 and the cylinder 50 such that when the annular sleeve 310 is released, the locking member 318 automatically returns to a position adjacent the impact block 56A under the resilient force of the resilient member 316. Here, the elastic element 316 is a compression spring, one end of which abuts against the bearing 86 and the other end of which abuts against an end face of the first annular portion 312 facing the second annular portion 314.

Under normal conditions, the elastic element 316 exerts an elastic force to make the annular sleeve 310 abut against the stop member 320, the locking element 318 is disengaged from the annular sleeve 310, and the second stop portion 326 is located inside the inner wall of the cylinder 50 under the action of the torsion spring 324. If the second stop 328 abuts against the end surface of the annular groove 57 of the impact block 56A, the impact block 56A cannot move in the direction approaching the piston 46. If the second stop 328 is located inside the inner wall of the cylinder 50 and the impact block 56A abuts against the thrust receiving portion 330 and faces away from the second stop 328, the impact block 56A can be moved axially by the punch 90, the impact block 56A can be moved away from the piston 46, and the locking element 318 can be pushed to rotate around the pin 322, so that the second stop 328 abuts against the inner wall of the cylinder 50, and the impact block 56A passes over the locking element 318, and the locking element 318 will be located in the annular groove 57 of the impact block 56A. At this time, if the impact block 56A continues to move in the direction approaching the piston 46, the second stopping portion 328 of the locking element 318 will abut against the end surface of the annular groove 57, and the first stopping portion 326 of the locking element 318 abuts against the inner wall of the cylinder, the locking element 318 cannot rotate around the pin 322, and the axial movement of the impact block 56A in the direction approaching the piston 46 is limited and cannot pass through the through hole 52. At this point, the collet sleeve 98 and the punch 90 are both free to move axially within the cylinder 50. However, since the axial movement of the impact block 56A in the direction approaching the piston 46 is restricted by the stopper mechanism 308, it cannot pass through the through hole 52, and the pressure change in the air chamber 54 cannot be generated, and the impact of the impact block 56A on the punch 90 and the operating tool 28 cannot be achieved.

When the annular sleeve 310 is pushed by the eccentric pin 14, against the elastic force of the elastic element 316, in the opposite direction, the second annular portion 314 thereof abuts against the thrust receiving portion 330 of the locking element 318, and the locking element 318 is pushed to rotate about the pin 322 against the force of the torsion spring 324 until the first and second stops 326, 328 simultaneously abut against the inner wall of the cylinder 50. At this time, the second stopping portion 328 of the locking element 318 is accommodated in a groove radially opened on the inner wall of the cylinder 50, and does not contact with the moving element in the cylinder 50, that is, the locking element 318 does not limit the axial movement of the impact block 56A in the cylinder 50. Thus, since both the collet sleeve 98 and the punch 90 are free to move axially within the cylinder 50, the collet sleeve 98 can move to a maximum displacement S1, and the punch 90 can move to a maximum displacement S2. At this point, the impact block 56A is able to pass through the through bore 52 and the axial movement of the impact block 56A is sufficient to cause the axial movement of the piston 46 to produce a pressure change within the air chamber 54, effecting an impact against the punch 90 and the working tool 28.

The functional mode switching operation state of the hammer drill 1B with respect to the switching mechanism 10B in the present embodiment is as follows.

Opening/closing of impact force transmission:

the control knob 12 in the switching mechanism 10B is rotated, the eccentric pin 14 does not contact the annular sleeve 310, the locking element 318 is disengaged from the annular sleeve 310, the second stopping portion 326 is located inside the inner wall of the cylinder 50 and abuts against the end surface of the annular groove 57 of the impact block 56A, the first stopping portion 326 of the locking element 318 abuts against the inner wall of the cylinder 50, the locking element 318 cannot rotate around the pin 322, and the axial movement of the impact block 56A in the direction approaching the piston 46 is limited and cannot pass through the through hole 52. When the operating tool 28 abuts against the workpiece, the reaction force pushes the intermediate member 88 to move backward, and the punch 90 in the intermediate member 88 moves toward the impact block 56A up to the maximum stroke S2, but the impact block 56A cannot move in the direction approaching the piston 46 due to the abutment by the locking member 318, and thus cannot transmit the impact force. At this time, the transmission of the impact force is in the off state. The control knob 12 in the switching mechanism 10B is rotated so that the eccentric pin 14 drives the annular sleeve 310 and the locking member 318 against the spring force, and the locking member 318 rotates relative to the cylinder 50 about the pin 322 until the first stop 326 and the second stop 328 simultaneously abut against the inner wall of the cylinder 50. When the operating tool 28 abuts against the workpiece, the reaction force pushes the intermediate member 88 to move backward, and the punch 90 in the intermediate member 88 moves toward the impact block 56A to reach the maximum stroke S2, because the second stopping portion 328 of the locking element 318 is accommodated in the radially opened groove on the inner wall of the cylinder 50 and does not contact the moving element in the cylinder 50, the impact block 56A cannot move backward, the sealing ring 55 passes through the through hole 52, and the sealed air chamber 54 cannot be formed between the impact block 56A and the piston 46. At this time, the transmission of the impact force is in the open state.

Opening/closing of rotational force transmission:

the control knob 12 in the switching mechanism 10B is rotated and the cam 16 pushes the switching member 20 to move backward, with its internal splines 24 engaging with the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, and rotates the cylinder 50 together with the bevel gear 64 through the clutch elements 70, 76. At this time, the transmission of the rotational force is in the open state. The control knob 12 in the switching mechanism 10B is rotated and the cam 16 pushes the switching member 20 forward, disengaging the internal splines 24 thereof from the external splines 66 of the bevel gear 64. Thus, the motor pinion 36 transmits the rotational force of the motor 33 to the bevel gear 64 through the rotational force transmitting mechanism 31, but the rotation of the bevel gear 64 is not transmitted to the cylinder 50, and the bevel gear 64 is idly rotated on the cylinder 50. At this time, the transmission of the rotational force is in the closed state.

Cylinder rotation lock on/off:

the control knob 12 in the switching mechanism 10B is rotated, the cam 16 pushes the switching member 20 forward, the outer teeth 22 thereof engage with the inner teeth 18 of the housing, and the clutch members 70, 76 are fixed with respect to the circumferential direction of the cylinder housing 2B, so that the cylinder 50 and the cylinder housing 2B are fixed with respect to the circumferential direction. At this time, the rotation lock of the cylinder 50 is in the open state. The control knob 12 in the switching mechanism 10B is rotated, the cam 16 pushes the switching member 20 to move backward, and the outer teeth 22 thereof are disengaged from the inner teeth 18 of the housing, so that the clutch members 70, 76 and the cylinder 50 are circumferentially rotatable with respect to the housing 2. At this time, the rotation lock of the cylinder 50 is in the off state.

Thus, the hammer drill can be respectively in the working modes of single hammer, single drill, hammer drill and hammer corner under the action of the switching mechanism 10B. However, since the moving direction of the annular sleeve 310 in the limiting mechanism 308 has a different function for switching functions than the former two embodiments, the position relationship between the cam 16 and the eccentric pin 14 on the corresponding control knob can be changed correspondingly to adapt to the requirements of different working modes.

Of course, the switching mechanism in the present invention can be simple. If only the on and off of the transmission of the impact force is controlled, the hammer drill can be in only two modes of operation, namely single drill and hammer drill. At this time, the control knob 12 only needs to be provided with the eccentric pin 14, and the limit mechanism is determined by different positions of the eccentric pin 14 to limit the displacement of the moving element, or the limit mechanism is released from limiting the axial displacement of the moving element. Or only controls the on and off of the transmission of the impact force and the on and off of the transmission of the rotating force, and the hammer drill can be in three working modes of a single hammer, a single drill and a hammer drill. At this time, the cam 16 on the control knob 12 cooperates with the eccentric pin 14 to determine the positions of the stopper mechanism and the rotational force transmitting mechanism, and accordingly, the structure of the switching element in the switching mechanism is also provided simply.

Claims (25)

1. A hammer drill, comprising: a housing (2); a motor (33) disposed in the housing to generate a rotational force; an operating tool (28); an impact force transmission mechanism (30) including a cylinder (50) rotatably supported in the housing and having axially extending first and second ends, an operating tool connected to the first end by a collet (96), a piston (46) disposed in the cylinder adjacent the second end and axially movable, a motion conversion mechanism converting a rotational force of the motor to a reciprocating motion of the piston, and a moving member (98; 90; 56A) disposed in the cylinder between the operating tool and the piston and axially movable, an air chamber (54) formed in the cylinder between the piston and the moving member, the cylinder having at least one through hole (52) providing fluid communication between the air chamber and an exterior of the cylinder; the rotational force transmission mechanism (31) includes a rotary cylinder and a gear for operating the tool; and a switching mechanism (10) for switching the operating mode between a first operating mode in which fluid communication between the through-hole and the air chamber is cut off and a second operating mode in which the through-hole is maintained in fluid communication with the air chamber, characterized in that: the switching mechanism includes a limit mechanism (108; 208; 308) that limits the amount of displacement of the moving element.

2. The hammer drill according to claim 1, wherein: the spacing mechanism (108; 208) includes a locking element (118; 218) that moves radially relative to the cylinder.

3. The hammer drill of claim 2, wherein: the limiting mechanism (108; 208) comprises an annular sleeve (110; 210) sleeved outside the air cylinder, and the annular sleeve drives the locking element to move between a position adjacent to the moving element and a position far away from the moving element.

4. The hammer drill of claim 3, wherein: the limiting mechanism (108; 208) further comprises an elastic element (116; 216) arranged between the annular sleeve and the cylinder.

5. The hammer drill according to claim 4, wherein: the resilient element is a compression spring.

6. The hammer drill according to claim 4, wherein: the annular sleeve body is annular and has an inner wall comprising a conical surface (114; 214) and a cylindrical surface (115; 215), the locking element being movable between the conical surface and the cylindrical surface.

7. The hammer drill according to claim 4, wherein: the locking element (118) is a steel ball.

8. The hammer drill according to claim 4, wherein: the locking element (218) includes a top portion (224) having a cylindrical cross-sectional shape and an extension (226) having a cross-sectional diameter that is less than the cross-sectional diameter of the top portion.

9. The hammer drill of claim 8, wherein: the cross-sectional diameter of the extension portion is gradually reduced from the top along the axial direction.

10. The hammer drill of claim 8, wherein: a groove (230) is formed in one end, adjacent to the extending portion, of the top portion, and the elastic piece (228) is contained in the groove.

11. The hammer drill of claim 8, wherein: the length of the extension part extending into the cylinder is larger than the distance between the outer wall of the moving element and the inner wall of the cylinder.

12. The hammer drill according to any one of claims 1 to 11, wherein: the moving element (98) is a collet sleeve that receives an operating tool.

13. The hammer drill of claim 12, wherein: the chuck sleeve comprises a front end for receiving an operation tool and a rear end accommodated in the cylinder, the sliding groove (100) is radially arranged from the outer wall and axially extends, the rolling body (101) is arranged between the cylinder and the chuck sleeve and accommodated in the sliding groove, and the chuck sleeve moves between one end, located at the front end of the adjacent chuck sleeve, of the sliding groove of the rolling body and the other end, located at the front end of the chuck sleeve, of the rolling body, of the sliding groove and the other end, located at the front end of the chuck sleeve.

14. The hammer drill of claim 13, wherein: and the cylinder is provided with a hole (119) axially spaced from the through hole, and the axial position of the hole is positioned in front of the rear end of the chuck sleeve when the rolling body is positioned at one end of the sliding groove adjacent to the front end of the chuck sleeve.

15. The hammer drill according to any one of claims 1 to 11, wherein: the moving element (90) is a punch in direct contact with an operating tool.

16. The hammer drill of claim 15, wherein: the punch comprises a front end in contact with an operating tool and a rear end accommodated in the cylinder, the sliding groove (92) is radially arranged from the outer wall and axially extends, a rolling piece (94) is arranged between the cylinder and the punch and accommodated in the sliding groove, and the punch moves between one end, located at the sliding groove, of the rolling piece, close to the front end of the punch and the other end, located at the sliding groove, of the rolling piece and the other end, located at the sliding groove, of the rolling body relative to the cylinder, of the punch.

17. The hammer drill of claim 16, wherein: and the cylinder is provided with a hole (219) which is axially spaced from the through hole, and the axial position of the hole is positioned in front of the rear end of the punch when the rolling element is positioned at one end of the sliding groove, which is adjacent to the front end of the punch.

18. The hammer drill according to claim 1, wherein: the spacing mechanism (308) includes a locking element (318) that pivots relative to the cylinder.

19. The hammer drill of claim 18, wherein: the limiting mechanism (308) comprises an annular sleeve (310) sleeved outside the air cylinder, and the annular sleeve drives the locking element to rotate between a position close to the moving element and a position far away from the moving element.

20. The hammer drill of claim 19, wherein: the limiting mechanism (308) further comprises an elastic element (316) arranged between the annular sleeve and the cylinder.

21. The hammer drill of claim 20, wherein: the annular sleeve (310) includes first (312) and second (314) axially extending annular portions, the first annular portion having an outer diameter greater than the outer diameter of the second annular portion, the inner diameters of the annular portions being the same.

22. The hammer drill according to any one of claims 18 to 21, wherein: the moving element is an impact block (56A) having a ring groove (57).

23. The hammer drill according to claim 1, wherein: the switching mechanism (10) includes a control knob (12) having an eccentric pin (14) that drives the limit mechanism between a position that defines the amount of axial displacement of the moving element and a position that releases the amount of axial displacement of the moving element.

24. The hammer drill of claim 23, wherein: the control knob further includes a cam (16) that drives a switching element (20) to move between a position that turns on the transmission of rotational force and a position that turns off the transmission of rotational force.

25. The hammer drill of claim 24, wherein: the cam also drives the switching element to move between a position that limits the rotation of the cylinder and a position that allows the cylinder to rotate.

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