JP2004167640A - Motor-driven hammer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven hammer equipped with a clutch mechanism for disengaging transmission of a drive motor torque to a hammer bit in case the working torque of the hammer bit to a work to be processed has exceeded a specified set value, in which it is possible to change the working torque set value of the hammer bit easily and widely without bringing about complication of the structure. <P>SOLUTION: The motor-driven hammer is equipped with a drive motor 121 for driving the hammer bit, a first power transmitting mechanism 131 to transmit the rotational output of the motor 121 upon converting into linear motions in the hammer bit long axis direction, a second power transmitting mechanism 139 to transmit the rotational output of the motor 121 to the hammer bit as the rotational output in the hammer bit circumferential direction, and the clutch mechanism 201 to disengage transmission of the torque of the motor 121 to the hammer bit by the second power transmitting mechanism 139 in case the working torque of the hammer bit to the work processed has exceeded the specified set value. The clutch mechanism 201 is structured so that the set value of the working torque for disengaging transmission of the torque of the motor 121 to the hammer bit can be changed freely within the specified range. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a hammer mechanism and a drill mechanism, and further includes a clutch mechanism that cancels transmission of a driving motor rotational force and regulates a rotation operation of the hammer bit in accordance with a working torque of the hammer bit on a workpiece during work. The present invention relates to an electric hammer configuration technology.
[0002]
[Prior art]
An example of an electric hammer having this type of clutch mechanism is disclosed in Japanese Utility Model Registration No. 25495578 (Patent Document 1). The electric hammer converts the rotational output of the drive motor into a linear motion in the major axis direction of the hammer bit and transmits the linear motion. The conversion mechanism drives the hammer bit by a hammer, and the rotational force of the drive motor is applied to the hammer bit. A rotation transmitting mechanism for transmitting the transmitted power to drill the hammer bit. An overload clutch that regulates the torque transmitted to the tip tool is set in the rotation transmission mechanism. In Patent Document 1, by arranging overload clutches having different regulation torques on two or more shafts of a rotation transmission mechanism, it is possible for an operator to select a so-called slip torque in multiple steps. The technology is disclosed.
[0003]
According to the above disclosed technology, a highly convenient electric hammer capable of switching the setting of the slip torque in multiple steps is configured, but for that, it is necessary to arrange an overload clutch for each slip torque setting value. However, there is room for improvement from the viewpoint of simplifying the structure of the electric hammer.
[0004]
[Patent Document 1]
Japanese Utility Model Registration No. 25495578
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of such a point, and is intended to cancel the transmission of the driving motor rotational force to the hammer bit when the working torque of the hammer bit for the workpiece exceeds a predetermined set value. An object of the present invention is to provide an electric hammer capable of easily and widely changing a working torque set value of a hammer bit without complicating the structure of a clutch mechanism.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in each claim is configured.
According to the first aspect of the present invention, an electric hammer having a hammer bit, a drive motor, first and second power transmission mechanisms, and a clutch mechanism is configured. The drive motor drives the hammer bit. The first power transmission mechanism converts the rotation output of the drive motor into a linear motion in the long axis direction of the hammer bit and transmits the linear motion to the hammer bit. As a result, the hammer bit is given a hammer operation on the workpiece. The second power transmission mechanism transmits the rotational force of the drive motor to the hammer bit as a rotational force in the hammer bit circumferential direction. As a result, the hammer bit is given a drilling operation on the workpiece. The clutch mechanism releases the transmission of the drive motor rotational force to the hammer bit by the second power transmission mechanism when the working torque of the hammer bit on the workpiece exceeds a predetermined set value. According to the present invention, when working on a workpiece using an electric hammer, for example, when the hammer bit is restricted by the workpiece and cannot rotate, the work of the hammer bit on the workpiece is performed. The torque increases to exceed the set value, whereby the transmission of the driving motor rotational force by the clutch mechanism is released. Therefore, it is possible to effectively prevent the electric hammer from swinging due to receiving the rotational force of the drive motor while the hammer bit is restrained by the workpiece.
[0007]
Further, in the electric hammer according to the present invention, the clutch mechanism is configured to be able to freely change a set value of a working torque for canceling transmission of the driving motor rotational force to the hammer bit within a predetermined range. Therefore, it is possible to freely change the timing of canceling the transmission of the driving motor rotational force to the hammer bit according to the material of the workpiece or other conditions during hammer drill work. Moreover, unlike the conventional case, it is not necessary to arrange a plurality of clutch mechanisms in accordance with each set value in order to set a plurality of work torque set values for canceling the transmission of the driving motor rotational force. Reasonable design becomes possible.
[0008]
(Invention of claim 2)
According to the second aspect of the present invention, in the second power transmission mechanism of the electric hammer according to the first aspect, the sun gear whose rotation is always restricted, and the sun gear which receives an output of the drive motor. And a shaft that rotates while being connected to the planetary gear and transmits the rotational force of the drive motor to the hammer bit. Then, the clutch mechanism is configured to allow rotation of the sun gear when the working torque of the hammer bit exceeds a set value, and thereby release transmission of the driving motor rotational force to the hammer bit.
[0009]
As an example of a specific configuration of the regulation and allowance of the rotation of the sun gear, for example, the sun gear is clamped with a predetermined urging force, and the planetary gear circulates around the sun gear whose rotation is regulated at all times. On the other hand, when the working torque received from the workpiece by the hammer bit exceeds the set value, the rotation force of the drive motor is used to rotate the sun gear through the planetary gear, and the drive motor rotation force Is preferably not transmitted to the hammer bit.
[0010]
(Invention of claim 3)
According to the third aspect of the present invention, in the electric hammer according to the second aspect, between the hammer bit and the shaft, the tool is driven to rotate by the shaft, thereby transmitting the driving motor rotational force to the hammer bit. Insert the holder. When the tool holder is interposed between the hammer bit and the shaft, when the transmission of the drive motor rotational force from the drive motor to the hammer bit is released, the work torque of the hammer bit to the workpiece is directly released. Need to be used for By the way, the tool holder is a member whose rotational torque tends to increase by the amount of the rotation being decelerated.However, disposing the clutch mechanism in a place where a large rotational torque acts is relatively necessary to operate the clutch mechanism. Requires a lot of power. On the other hand, in the present invention, it is not necessary to dispose a clutch mechanism in such a tool holder, so that the set torque for canceling the transmission of the driving motor rotational force is adjusted to the extremely large working torque received by the hammer bit at the time of work. It is not necessary to set a large value and therefore to set the strength of the member of the clutch mechanism high, which contributes to rationalization of the design of the electric hammer.
[0011]
(Invention of claim 4)
According to the invention described in claim 4, the clutch mechanism in the electric hammer according to claim 2 or 3 is configured such that the same urging force is simultaneously applied to opposing portions of the peripheral surface of the sun gear through an operation of an operator. , The rotation of the sun gear is regulated. By applying the same urging force to the opposing parts of the sun gear peripheral surface at the same time by the operator's operation, the rotation of the sun gear and the control of the rotation allowance can be performed more reliably and quickly. And the durability of the clutch mechanism itself can be improved.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a hammer drill according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the entire configuration of a hammer drill 101 according to the present embodiment. The hammer drill 101 according to the present embodiment corresponds to the “electric hammer” of the present invention. The outer periphery of the hammer drill 101 according to the present embodiment is generally formed by a main body 103 having a motor housing 105, a gear housing 107, and a hand grip 111. A hammer bit 163 is attached to the tip end (the left end area in the drawing) of the main body 103 of the hammer drill 101.
[0013]
A drive motor 121 is arranged in the motor housing 105. In the gear housing 107, a first power transmission mechanism 131, an air cylinder mechanism 133, a striking force transmission mechanism 135, a second power transmission mechanism 139, and a clutch mechanism 201 are arranged. In the gear housing 107, a tip tool mechanism 137 is disposed on the tip side (the left end side in FIG. 1) of the striking force transmission mechanism 135. A hammer bit mounting chuck 109 for detachably fixing the hammer bit 163 is disposed on the tip tool mechanism 137. The first power transmission mechanism 131, the air cylinder mechanism 133, the second power transmission mechanism 139, and the clutch mechanism 201 among the respective mechanisms in the motor housing 105 have detailed structures shown not only in FIG. 1 but also in FIG. ing.
[0014]
On the other hand, the hammer bit 163 is relative to the tool holder 161 arranged in the longitudinal direction of the hammer bit 163 from the gear housing 107 into the tip tool mechanism 137 in the longitudinal direction. Reciprocation is possible, and the relative rotation in the circumferential direction is held in a restricted state.
[0015]
The drive motor 121 in the motor housing 105 is energized and driven by an operator turning on a trigger switch 113 provided on the hand grip 111, and the rotational force of the drive motor 121 is output to the output shaft 123.
[0016]
As shown in FIGS. 1 and 2, the first power transmission mechanism 131 in the gear housing 107 includes a gear 145 meshing and engaging with the output shaft 123, a first driven shaft 147 rotating with the gear 145, and a first driven shaft 147. A crank 149 having one end connected to a position eccentric from the rotation center by a predetermined distance, and a driver 153 attached to the other end of the crank 149 are mainly constituted.
[0017]
On the other hand, as shown in FIGS. 1 and 2, the second power transmission mechanism 139 in the gear housing 107 includes an internal gear 171, a carrier 173, a sun gear 175, a planetary gear 177, a second driven shaft 179, and a second driven The rotation torque transmission gear 181 provided on the shaft 179, the tool holder 161, the rotation torque transmission gear 162 provided on the tool holder 161, the torque transmission pin 183, and the torque transmission groove 165 on the peripheral surface of the hammer bit 163 are mainly constituted. . Among them, the second driven shaft 179 corresponds to the “shaft connected to the planetary gear” in the present invention. The arrangement of the internal gear 171, the carrier 173, the sun gear 175, the planetary gear 177, and the second driven shaft 179 is shown in FIG. 3, which is a cross section taken along the line BB in FIG. This is shown in detail in FIG.
[0018]
The internal gear 171 of the second power transmission mechanism 139 is engaged with the output shaft 123. The carrier 173 is fitted on the inner peripheral surface of the internal gear 171 and receives the rotation of the internal gear 171 by the output shaft 123 via the planetary gear 177. The sun gear 175 is arranged below the carrier 173. As will be described later, the rotation of the sun gear 175 is restricted in a normal state. A plurality of planetary gears 177 are provided on the lower surface side of the carrier 173 so as to be rotatable about a rotation shaft 177a, and mesh with and engage with the inner periphery of the internal gear 171 and the outer periphery of the sun gear 175, respectively. It is possible to go around 175.
[0019]
The second driven shaft 179 is vertically penetrated and arranged in the center area of the carrier 173. The carrier 173 transmits the rotational force to the second driven shaft 179 by the rotation torque transmitting ball 143 engaging with the groove of the second driven shaft 179. Specifically, when the internal gear 171 is rotated by the rotation output of the output shaft 123 of the drive motor 121, the planetary gear 177 is rotated around the rotation shaft 177 a by the internal gear 171 while meshing with the sun gear 175. Meanwhile, it is configured to orbit around the sun gear 175. By the orbiting operation of the planet gear 177, the carrier 173 to which the rotating shaft 177a of the planet gear 177 is mounted rotates around the second driven shaft, whereby the second driven shaft 179 is rotated via the rotating torque transmitting ball 143. It is driven to rotate. The engagement of the rotary torque transmitting ball 143 with the groove of the second driven shaft 179 can be released by switching the changeover switch 141 from the hammer drill mode to the hammer mode. 1 and 2, for easy understanding, the left switch 141 of the second driven shaft 179 is shown as being set in a hammer drill mode, while the right switch 141 is set in a hammer mode. It is shown as a closed state.
[0020]
The rotation torque transmission gear 181 is formed in the upper end region of the second driven shaft 179, while the rotation torque transmission gear 162 is disposed on the right end side of the tool holder 161 and can be engaged with the rotation torque transmission gear 181 in a beveled manner. Is done. Therefore, when the second driven shaft 179 rotates, the tool holder 161 is configured to be rotatable in the circumferential direction via the two rotation torque transmission gears 181 and 162.
[0021]
A torque transmission pin 183 is disposed at an appropriate position of the tool holder 161 in the tip tool mechanism 137. The torque transmission pin 183 fits into a torque transmission groove 165 formed in a notch on the peripheral surface of the hammer bit 163. The torque transmission groove 165 is formed in a long shape in the longitudinal direction of the hammer bit 163. Even when the hammer bit 163 linearly moves relative to the tool holder 161 to perform a hammer operation, the torque of the torque transmission pin 183 can be increased. The engagement with the transmission groove 165 is maintained.
[0022]
The air cylinder mechanism 133 includes a cylinder 151 that slidably accommodates the driver 153 and the striker 155 in the bore, and an air chamber defined between the driver 153 and the striker 155 in the bore of the cylinder 151. 157 as a main component.
[0023]
The striking force transmitting mechanism 135 mainly includes an impact bolt 159 that linearly moves in response to the striking of the striker 155 that moves linearly at a high speed via the air cylinder mechanism 133. The impact bolt 159 is configured as a rod-shaped member having a long axis in the direction of the linear movement (the left-right direction in FIG. 1), and its outer peripheral surface is in sliding contact with the inner peripheral surface of the tool holder 161 in a reciprocating manner.
[0024]
The detailed structure of the clutch mechanism 201 is shown in plan view in FIG. 5, which is a cross-sectional view taken along line AA in FIG. In FIG. 5, some elements other than the main parts of the hammer drill 101 are not shown for convenience. The clutch mechanism 201 includes a first pressing pin 203, a first holder 205, a second pressing pin 207, a second holder 209, a biasing spring 211, a support plate 213, a rotation receiving portion 215, a screw portion 216, and a rotation dial 217. It is configured as a subject. The first pressing pin 203 is fitted to the first holder 205 and engages with the engaging projection 176 of the sun gear 175 arranged around the second driven shaft 179. Further, the second pressing pin 207 is fitted to the second holder 209 and engages with the engaging projection 176 of the sun gear 175 at a position facing the first pressing pin 203. Further, the first holder 205 is urged in the direction of the sun gear 175 (rightward in FIG. 5) by the urging spring 211 interposed between the first holder 205 and the support plate 213, while the second holder 209 is urged. The urging force of the urging spring 211 acts to the left in the drawing via the support plate 213 and the screw portion 216. Accordingly, the opposing urging forces acting on the respective holders 205 and 209 cause the respective pressing pins 203 and 207 to resiliently engage with the respective engagement protrusions 176 from the mutually opposing portions of the sun gear 175 with the same urging force. Will be engaged.
[0025]
Accordingly, the rotation of the sun gear 175 about the second driven shaft 179 is restricted by the first pressing pin 203 and the second pressing pin 207 being resiliently engaged with the engagement protrusions 176. This state is defined as the "clamp state" of the sun gear 175. Further, in a normal working state, the rotation of the sun gear 175 is restricted by the first pressing pin 203 and the second pressing pin 207 which act on the peripheral surface of the sun gear 175 so as to oppose each other. As a result, the working torque of the hammer bit 163 on the workpiece may increase to such an extent that the rotation restriction of the sun gear 175 by the first pressing pin 203 and the second pressing pin 207 is released. The work torque set value at which the rotation restriction of the sun gear 175 is released is defined by the urging force of the first pressing pin 203 and the second pressing pin 207 at the positions of the sun gear 175 facing each other. .
[0026]
The rotation receiving portion 215 and the screw portion 216 are formed in an integral rod shape. The rotation receiving portion 215 is fitted to a fitting portion 217a formed in the tip region (right end region in FIG. 5) of the rotary dial 217, and the screw portion 216 is connected to one end of the second holder 209 (in FIG. 5). It is screwed into a female screw portion 209 a formed on the left end side), and its right end is connected to the support plate 213. In addition, the rotation receiving portion 215 and the screw portion 216 formed integrally with the rotation dial 217 through the rotation operation of the rotation dial 217 through the fitting of the rotation receiving portion 215 to the fitting portion 217a. It is configured to rotate integrally. On the other hand, when the screw portion 216 is rotated around the axial direction via the rotation receiving portion 215, the rotation receiving portion 215 and the screw portion 216 are screwed together with the screw portion 216 and the female screw portion 209a. The operation of moving closer to and away from the rotary dial 217 is performed. In FIG. 5, FIG. 6 shows a state in which the rotation receiving portion 215 and the screw portion 216 are relatively moved rightward by a small amount so as to be relatively separated from the rotary dial 217.
[0027]
The hammer drill 101 according to the present embodiment is configured as described above. Next, the operation and usage of the hammer drill 101 will be described. When the operator turns on the trigger switch 113 while holding the hand grip 111 shown in FIG. 1, the drive motor 121 is energized and driven. When the drive motor 121 is driven, the rotation output of the drive motor 121 is transmitted to the gear 145 via the output shaft 123, whereby the first driven shaft 147 is driven to rotate together with the gear 145. One end of the crank 149 revolves around the first driven shaft 147 due to the rotation of the first driven shaft 147, and the driver 153 loosely fitted to the other end of the crank 149 reciprocates linearly in the bore of the cylinder 151. I do.
[0028]
With the linear movement of the driver 153, the striker 155 linearly moves toward the impact bolt 159 at a speed higher than the linear movement of the driver 153 by the action of a so-called air spring. When the striker 155 collides with the impact bolt 159, the kinetic energy of the striker 155 is transmitted to the impact bolt 159, and the impact bolt 159 linearly moves toward the hammer bit 163 at high speed. When the impact bolt 159 collides with the hammer bit 163, the kinetic energy of the impact bolt 159 is transmitted to the hammer bit 163, and the hammer bit 163 linearly moves forward at a high speed. The work will be performed.
[0029]
On the other hand, regarding the second power transmission mechanism, as shown in FIGS. 2 to 4, the rotation output of the drive motor 121 is transmitted to the internal gear 171 via the output shaft 123, and the planetary gear 177 is connected to the sun gear by the internal gear 171. The carrier 173 rotates around the 175, and the carrier 173 rotates with the circling of the planetary gear 177. As shown in FIG. 2, when the mode changeover switch 141 is set to the hammer drill mode, the rotating operation of the carrier 173 is transmitted to the second driven shaft 179 via the rotating torque transmitting ball 143. At this time, the sun gear 179 is brought into a clamped state by the first pressing pin 203 and the second pressing pin 207 of the clutch mechanism 201 shown in FIG. As a result, the rotation of the sun gear 179 is restricted.
[0030]
As a result, when the second driven shaft 179 is rotationally driven, the tool holder 161 is rotationally driven around its long axis by the beveled engagement of the rotational torque transmitting gears 181 and 162, and the torque transmitting pin 183 shown in FIG. The rotary operation of the hammer bit 163 is performed via the. As a result, the hammer bit 163 rotates in the circumferential direction, thereby performing a drilling operation on a workpiece (not shown).
[0031]
When the mode changeover switch 141 shown in FIG. 2 is switched from the hammer drill mode to the hammer mode, the transmission of the rotational force from the carrier 173 to the second driven shaft 179 by the rotational torque transmitting ball 143 is released, and the rotation of the hammer bit 163 is stopped. The driving is released.
[0032]
When the hammer bit 163 is driven on the workpiece in the hammer drill mode, the hammer bit 163 performs a drill operation on the workpiece with a predetermined work rotation torque (hereinafter simply referred to as work torque). When the working torque does not exceed a predetermined set value, the rotational force of the drive motor 121 is limited to the internal gear 171, the planetary gear 177, the carrier 173, the second driven shaft 179, the rotational torque transmitting gears 181 and 162, and the tool holder. 161 is transmitted to the hammer bit 163 via the torque transmission pin 183. As described above, the planetary gear 177 disposed on the carrier 173 rotates around the sun gear 175 whose rotation is restricted, so that the carrier 173 is rotationally driven (see FIG. 5).
[0033]
By the way, when driving in the hammer drill mode, the hammer bit 163 may be restrained by the workpiece, and the working torque of the hammer bit 163 on the workpiece may suddenly increase beyond the set value described above. In this case, the rotation of the hammer bit 163 is locked due to the restraint of the hammer bit 163 by the workpiece, and as a result, the respective rotation operations of the tool holder 161, the second driven shaft 179, and the carrier 173 are restricted. Will be done. In this case, a relative movement operation is allowed between the carrier 173 whose rotation is restricted and the internal gear 171 that is about to be rotated by the drive motor 121. As a result, the rotation output of the drive motor 121 is transmitted to the sun gear 175 via the planetary gear 177 meshed and engaged with the internal gear 171. As a result, a rotational torque resulting from the rotational output of the drive motor 121 acts on the sun gear 175 through the internal gear 171 and the planetary gear 177.
[0034]
Due to this rotational torque, as shown in FIG. 6, the engaging projection 176 of the sun gear 175 overcomes the clamping force of the first pressing pin 203 and the second pressing pin 207, and both the pressing pins 203, 207 engage the engaging projection 176. And the sun gear 175 is allowed to rotate. As a result, the rotational force of the drive motor 121 is used to rotationally drive the sun gear 175 without being transmitted to the hammer bit 163, and the clutch release during drill driving is realized.
[0035]
By the way, when actually performing a working operation on a workpiece using the hammer drill 101, it is necessary to appropriately change the set value of the working torque for releasing the clutch in accordance with the material of the workpiece or another working mode. Cases can arise. When changing the set value of the working torque in the hammer drill 101 according to the present embodiment, as shown in FIG. 5, the operator rotates the rotary dial 217 appropriately. When the rotary dial 217 is rotated, the screw portion 216 integrated with the rotation receiving portion 215 receiving the rotation of the rotary dial 217 generates a screwing action with the female screw portion 209a. As a result, the rotation receiving portion 215 and the screw portion 216 relatively move toward and away from the rotary dial 217.
[0036]
Then, the amount of compression of the biasing spring 211 interposed between the support plate 213 and the first holder 205 changes, whereby the first pressing pin 203 fitted to the first holder 205 attaches to the sun gear 175. The power changes. At the same time, the urging force of the urging spring 211 through the support plate 213 and the threaded portion 216 in the left direction in the drawing is applied to the sun gear 175 by the second holder 209 and the second pressing pin 207. It changes by the same amount as the first pressing pin 203. That is, the urging force of the urging spring 211 acts on the first holder 205 and the support plate 213 in directions opposite to each other. Accordingly, the urging force received by the support plate 213 from the urging spring 211 acts on the screw portion 216 and the second holder 209 from the distal end of the screw portion 216, so that the first pressing pin 203 and the second pressing pin 207 have The same urging force (elastic force) acts simultaneously in opposition to each other.
[0037]
As a result, as a clamping force on the sun gear 175, the first pressing pin 203 and the second pressing pin 207 cause mutual movement of the sun gear 175 as compared with the case where only one side of the sun gear 175 is urged and clamped. Since the opposing portions are doubled and clamped, and the rotating operation of the rotary dial 217 further doubles the opposing clamping forces of the first pressing pin 203 and the second pressing pin 207, so that the clamping force is approximately four times larger. The force will act. Therefore, in the present embodiment, it is possible to greatly increase the clamping force of the sun gear 175 by a small amount of operation of the rotary dial 217, and to quickly and rationally increase the set value for releasing the clutch. Further, by applying equal forces from positions opposing each other toward the center of the sun gear 175, it is possible to avoid applying a biased force to the sun gear 175 and improve the durability of the clutch element 201. It becomes possible.
[0038]
When the set value of the working torque is reduced, the operation reverse to the above operation is reduced, so that the clamping force of the sun gear 175 is greatly reduced by a small amount of operation of the rotary dial 217, and the set value is quickly and rationally reduced. It is possible to reduce.
[0039]
A stopper 205a for defining an upper limit value of the clamping force of the sun gear 175 is formed in a protruding shape on the side of the first holder 205 toward the support plate 213. The stopper 205a prevents the rotation receiving portion 215 from falling off from the fitting portion 217a due to excessive rotation operation of the rotary dial 217 by an operator, or the support plate compresses the urging spring 211 more than necessary. This has the effect of restricting the member from being damaged.
[0040]
Further, in the present embodiment, since the sun gear 175 is clamped from a position where the sun gear 175 opposes each other, the sun gear 175 is clamped in a well-balanced state without deflection, and the durability of the member is improved. It is possible. Further, two biasing springs 211 are arranged in parallel, so that the biasing force acts widely in the width direction of the first holder 205, and the effect of the biasing force on the sun gear 175 does not become unevenly distributed. It is devised as follows. Of course, it is also possible to arrange only one of the urging springs to achieve the same effect.
[0041]
According to the present embodiment, when the hammer bit 163 is restricted by the work material and cannot be rotated when performing the work on the work material using the hammer drill 101, the work of the hammer bit 163 on the work material is performed. When the torque increases and exceeds the set value, the rotation of the sun gear 175 is allowed. Thus, the transmission of the torque of the drive motor 121 to the hammer bit 163 through the second power transmission mechanism 139 is released by the clutch mechanism 201. Accordingly, it is possible to effectively prevent the hammer drill 101 from swinging due to receiving the rotational force of the drive motor 121 while the hammer bit 163 is restrained by the workpiece.
[0042]
Further, in the present embodiment, when the operator rotates the rotary dial 217, the first pressing pin 203 and the second pressing pin 207 are moved within the screwing operation range between the screw portion 216 and the second holder. It is configured so that the clamping force to the sun gear 175 can be changed steplessly. In addition, the clamping force of the sun gear 175 can be changed by operating the rotary dial 217 set outside the hammer drill 101, particularly on the upper side surface of the motor housing 105, so that the operation convenience is improved.
[0043]
Further, in the present embodiment, the release of the transmission of the rotational force of the drive motor 121 by the clutch mechanism 201 is performed not by providing the tool holder on which the working torque of the hammer bit 163 directly acts but by restricting the rotation of the sun gear 175. Since the clutch mechanism 201 does not need to be designed in strength according to a large working torque, it contributes to rationalization of the design of the hammer drill 101.
[0044]
Further, in the clutch mechanism 201 according to the present embodiment, when the rotary dial 217 is operated, the two pressing pins 203 and 207 simultaneously apply a clamping force to the sun gear 175 at locations where the sun gear 175 faces each other. By operating only one rotary dial 217, it becomes possible to apply a clamping force to the sun gear 175 on a scale of 2 × 2 × 4 times in total, thereby canceling the transmission of the torque of the drive motor 121. It is possible to quickly and rationally change the working torque set value to be a reference for the operation. In addition, the configuration in which the circumferential surface of the sun gear 175 is simultaneously clamped from a plurality of positions in opposition to each other with the same force can equalize the urging force acting on the sun gear 175 and prevent the biased force from acting. Therefore, the durability of the clutch mechanism 201 can be improved.
[0045]
In view of the above, the following aspects are possible. Ie
(Aspect 1) The electric hammer according to claim 4, wherein the urging force on the opposing portions of the sun gear is configured to act simultaneously by an operation of one operation member by an operator. An electric hammer characterized by the above. In this case, the “one operation member” corresponds to the rotary dial 217 in the present embodiment.
[0046]
(Aspect 2) The electric hammer according to claim 4 or 1, wherein the clutch mechanism has at least two clamp members for clamping a sun gear, and one of the clamp members is operated by operating the operation member. The clamp member presses the sun gear, and the other clamp member presses the sun gear from the side opposite to the one clamp member. As a result, the two clamp members opposing the clamp members can quickly and rationally clamp the sun gear, thereby facilitating the work of changing the set value of the working torque.
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when the working torque of a hammer bit with respect to a workpiece exceeds a predetermined set value, the structure of the clutch mechanism for releasing the transmission of the driving motor rotational force to the hammer bit is complicated. Thus, an electric hammer capable of easily and widely changing the set value of the working torque of the hammer bit has been provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an entire configuration of a hammer drill according to the present embodiment.
FIG. 2 is a partial cross-sectional view showing a configuration of a main part of the hammer drill according to the present embodiment.
FIG. 3 is a sectional view taken along line BB in FIG. 2;
FIG. 4 is a sectional view taken along line CC in FIG. 2;
FIG. 5 is a sectional view taken along line AA in FIG. 2; FIG. 5 shows a state in which the rotation of the sun gear is restricted.
FIG. 6 is a sectional view taken along line AA in FIG. 2; FIG. 6 shows a state where the sun gear is about to be rotated.
[Explanation of symbols]
101 Hammer drill
103 body
105 Motor housing
107 gear housing
109 Hammer bit mounting chuck
111 hand grip
113 Trigger switch
121 drive motor
123 output shaft
131 1st power transmission mechanism
133 Air cylinder mechanism
135 Impact force transmission mechanism
137 Tip tool mechanism
139 Second power transmission mechanism
141 Mode switch
143 Rotating torque transmission ball
145 gear
147 First driven shaft
149 crank
151 cylinder
153 driver
155 striker (impactor)
157 air chamber
159 Impact bolt
161 Tool holder
162 rotating torque transmission gear
163 hammer bit
165 Torque transmission groove
171 Internal Gear
173 career
175 sun gear
176 engaging projection
177 planetary gear
179 Second driven shaft
181 Rotary torque transmission gear
183 Torque transmission pin
201 Clutch mechanism
203 1st pressing pin
205 1st holder
207 Second pressing pin
209 Second holder
211 biasing spring
213 Support plate
215 Rotation receiving part
216 screw
217 Rotary dial

Claims (4)

Hammer bit,
A drive motor for driving the hammer bit,
A first power transmission mechanism that converts the rotation output of the drive motor into a linear motion in the long axis direction of the hammer bit and transmits the linear motion to the hammer bit;
A second power transmission mechanism that transmits the rotational force of the drive motor to the hammer bit as a rotational force in the circumferential direction of the hammer bit;
When the working torque of the hammer bit on the workpiece exceeds a predetermined set value, a clutch mechanism that cancels transmission of the driving motor rotational force to the hammer bit by the second power transmission mechanism,
The electric hammer according to claim 1, wherein the clutch mechanism is configured to be capable of changing a set value of the working torque for canceling transmission of the driving motor rotational force to the hammer bit within a predetermined range. The electric hammer according to claim 1,
The second power transmission mechanism is configured to rotate while being connected to a sun gear whose rotation is always regulated, a planetary gear that rotates around the sun gear by receiving an output of the drive motor, and a planetary gear that is connected to the planetary gear. A shaft for transmitting the driving motor rotational force to the hammer bit,
The clutch mechanism is configured to allow the rotation of the sun gear when the working torque of the hammer bit exceeds the set value, thereby canceling the transmission of the driving motor rotational force to the hammer bit. An electric hammer, characterized in that: 3. The electric hammer according to claim 2, wherein a tool holder that transmits a driving motor rotational force to the hammer bit by being rotationally driven by the shaft is interposed between the hammer bit and the shaft. 4. An electric hammer, characterized in that: 4. The electric hammer according to claim 2, wherein the clutch mechanism simultaneously applies urging forces to opposing portions of a peripheral surface of the sun gear through an operation of an operator to operate the sun gear. 5. The setting value of the working torque for canceling the transmission of the driving motor torque is configured to be changeable by freely changing the biasing force by the clutch mechanism within a predetermined range. An electric hammer, characterized in that:

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