Patent Publication Number: US-2023135467-A1

Title: Electric impact hammer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation-application of the International Patent Application No. PCT/CN2021/141924, filed on Dec. 28, 2021, which claims the priority of the Chinese Patent Application No. 202011632626.6, filed on Dec. 31, 2020, and the contents of which are hereby incorporated in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the field of electric tools, in particular to an electric impact hammer used for drilling or chiseling on concrete, floor slabs, brick walls and stone materials. 
     BACKGROUND 
     A traditional electric impact hammer is arranged with a mechanism of a crank connecting rod or a pendulum rod bearing to drive a piston to reciprocate, such that the impact hammer in the cylinder is driven by the piston to perform an impact output. 
     Please refer to the Chinese Invention Patent No. CN101312807B of Bosch Co., Ltd., which discloses an electric hammer. The electric hammer drives an intermediate shaft to rotate through a motor. The intermediate shaft is arranged parallel to the lower part of the motor and provided with a pendulum rod bearing and a rotary input gear, and the intermediate shaft drives a pendulum rod of the pendulum rod bearing to swing and drives a piston in a cylinder to reciprocate. The cylinder is fixed with a driving gear which meshes with the rotary input gear, and the rotary input gear drives the cylinder to rotate together through the driving gear. However, the volume of the electric hammer is increased by means of impact driven by the pendulum rod bearing, meanwhile the weight of the pendulum rod bearing is relatively large. Please refer to Chinese Patent No. CN2860757Y of Zhejiang Haiwang Electric Co., Ltd., which discloses an electric hammer, wherein the electric hammer has a motor, which is perpendicular to a cylinder and arranged below the cylinder. The motor drives an eccentric shaft to rotate, and the eccentric shaft drives a piston to reciprocate through a connecting rod. The piston pushes the electric hammer for impact output, but the electric hammer needs to make more space to accommodate the structure of the crank connecting rod, in addition, the weight of the crank connecting rod is relatively large. 
     Therefore, it is desired to provide a new impact electric hammer for reducing the volume and weight of the impact electric hammer. 
     SUMMARY OF THE INVENTION 
     In order to solve the above problems, the present disclosure provides a miniaturized electric impact hammer. 
     To achieve the above-mentioned object, an impact electric hammer comprises a housing, a motor retained in the housing, and an impact assembly and a rotating assembly driven by the motor. The rotating assembly includes an output shaft connected to the front end of the motor and a cylinder driven by the output shaft, the motor drives the output shaft to drive the cylinder to rotate. The impact assembly includes a piston slidably arranged in the cylinder, the piston slides back and forth along the inside of the cylinder, and the cylinder drives the piston to rotate together. The piston is provided with an accommodating groove running through the rear end surface and a pair of through holes communicating with the accommodating groove and running through the outer periphery, the front end of the output shaft is inserted in the accommodating groove and provided with a corrugated groove located in the front end of the outer periphery, the corrugated groove is connected end to end along the outer periphery of the output shaft and has an axial front end and an axial rear end. The impact assembly includes a steel ball partially accommodated in the corrugated groove, the other part of the steel ball is accommodated in the through hole, when the output shaft rotates, the steel ball moves between the axial front end and the axial rear end of the corrugated groove to drive the piston to reciprocate along the axial direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view of an electric impact hammer of the present disclosure, wherein a piston of the electric impact hammer is arranged at a rear end position; 
         FIG.  2    is a cross-sectional view of the electric impact hammer of  FIG.  1   , wherein the piston of the impact electric hammer is arranged at a front end position; 
         FIG.  3    is an enlarged view of a portion of the electric impact hammer of  FIG.  1   ; 
         FIG.  4    is a cross-sectional view of a motor and a planetary gear assembly of the electric impact hammer of  FIG.  1   ; 
         FIG.  5    is a perspective view of a portion of the planetary gear assembly of  FIG.  4   ; 
         FIG.  6    is a perspective view of a cylinder, a clutch assembly and a portion of a planetary gear assembly of an electric impact hammer of the present invention; 
         FIG.  7    is a cross-sectional view of a cylinder sleeve assembly and a clutch assembly of the electric impact hammer of  FIG.  1   ; 
         FIG.  8    is a cross-sectional view of the cylinder and a transmission sleeve of the electric impact hammer of  FIG.  7   ; 
         FIG.  9    is a perspective view of a cylinder of an electric impact hammer of the present disclosure; 
         FIG.  10    is a front view of a piston of an electric impact hammer of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments of the present disclosure are further described below by referring to the accompanying drawings and examples. 
     Reference to  FIGS.  1  to  10   , the present disclosure provides an electric impact hammer  100 . In the present disclosure, a direction parallel to an output direction of a motor  1  of the electric impact hammer  100  is defined as a front-rear direction. The impact hammer  100  includes a housing  101  extending along the front-rear direction, a motor  1  received in the housing  101 , a drive assembly  2  driven by the motor  1 , and a chisel head detachably mounted at an end of the drive assembly  2 . The drive assembly  2  is received in the housing  101  and includes an impact assembly  20  and a rotating assembly  50 , the motor  1  drives the impact assembly  20  to compress air, such that the impact assembly  20  is ejected to impact the chisel head to perform an impact output. The motor  1  drives the rotary assembly  50  to drive the chisel head to perform a rotary output. 
     The rotating assembly  50  includes a planetary gear assembly  51 , a clutch assembly  52 , a cylinder sleeve assembly  53  and a rotating sleeve assembly  54 , and the planetary gear assembly  51 , the clutch assembly  52 , the cylinder sleeve assembly  53 , and the rotating sleeve assembly  54  are in transmitted connection to a front end of the motor  1 . The motor  1  is arranged with a motor shaft  1   a  extending in the front-rear direction, the front end of the motor shaft  1   a  is engaged with the planetary gear assembly  51 . The clutch assembly  52  is in transmitted connection to a front of the planetary gear assembly  51 , sleeves the cylinder sleeve assembly  53 , and drives the cylinder sleeve assembly  53  to rotate together with the clutch assembly  52 . 
     The electric impact hammer  100  in the present embodiment is an electric angular impact hammer, which defines the output direction of the chisel head of the electric impact hammer  100  to be a downward direction. The rotary sleeve assembly  54  is in transmitted connection to a lower part of a front end of the cylinder sleeve assembly  53 . The rotary sleeve assembly  54  is perpendicular to the cylinder sleeve assembly  53 , and is extending downwardly toward an outside of the housing  101 . The chisel head is accommodated in the rotary sleeve assembly  54  and rotates together with the rotating sleeve assembly  54 . 
     Reference to  FIGS.  1  and  7   , the cylinder sleeve assembly  53  includes a cylinder  531  extending along the front-rear direction and an input gear  532  sleeving a front end of the cylinder  531 . The input gear  532  is fixed on the cylinder  531  and rotates together with the cylinder  531 . The cylinder  531  is supported in the housing  101  by two bearings, which are fixed at the front and rear and are spaced apart from each other. 
     Reference to  FIGS.  4  to  6   , the planetary gear assembly  51  includes an output shaft  511 , an inner ring gear  512 , a plurality of a first planetary gears  513 , a sun gear  514 , a plurality of a second planetary gears  515 , and a planetary carrier  516 . The output shaft  511  extends along the front-rear direction. A rear end of the output shaft  511  is supported in the housing  101  by a bearing, and a front end of the output shaft  511  is supported on an inner wall of the cylinder  531 . The inner ring gear  512  is fixedly arranged in the housing  101 , and an inner wall of the inner ring gear  512  engages with the first planetary gear  513 . 
     The output shaft  511  defines a receiving groove  511   a  running through a rear end surface of the output shaft  511  and is arranged with a plurality of mounting seats  511   b  communicating with the receiving groove  511   a  and running through an outer periphery of the output shaft  511 . In the present embodiment, the output shaft  511  is provided with two mounting seats  511   b  in the circumferential direction. The front end, in an axial direction, of the motor shaft  1   a  is inserted into the receiving groove  511   a,  and two first planetary gears  513  are connected with the mounting seats  511   b  in relative rotation and engage with the motor shaft  1   a  received in the receiving groove  511   a,  the motor shaft  1   a  drives the output shaft  511  to rotate via the first planetary gear  513 . 
     The sun gear  514  is disposed at a front of the first planetary gears  513  and fixed on the output shaft  511 , so that the sun gear  514  and the output shaft  511  rotate together. In the present embodiment, the sun gear  514  and an outer ring of the output shaft  511  are in interference fit with each other. In other embodiments, the sun gear  514  may alternatively be integrally formed with the output shaft  511 . Two sides of each second planetary gear  515  are respectively engaged with the sun gear  514  and the inner ring gear  512 . The planetary carrier  516  sleeves an outer periphery of the rear end of the cylinder  531 , and the output shaft  511  runs through the planetary carrier  516  and extends into the cylinder  531 . The rear end of the planetary carrier  516  is provided with three pins  516   a.  The three pins  516   a  are fixedly inserted into the rear end of the planetary carrier  516  and are running through and supporting the second planetary gears  515 . The second planetary gear  515  drives the planetary carrier  516  to rotate together with the second planetary gear  515  via the pins  516   a.    
     Refer to  FIG.  1   ,  FIG.  7    and  FIG.  8   , the clutch assembly  52  includes a spring  522  and a transmission sleeve  521  sleeving the outer periphery of the cylinder  531 , the transmission sleeve  521  and the cylinder  531  are connected by a keyway and rotate together, and a front end of the drive sleeve  521  abuts against a rear bearing supporting the cylinder  531 . The front end of the planetary carrier  516  is engaged with the rear end of the transmission sleeve  521 , and that is, each of the front end surface of the planetary carrier  516  and the rear end surface of the transmission sleeve  521  has a concave-convex structure  521   a,  so that the front end surface of the planetary carrier  516  and the rear end surface of the transmission sleeve  521  can engage with each other through the concave-convex structure  521   a.    
     The spring  522  sleeves the planetary carrier  516 . A front end of the spring  522  is pressed against the planetary carrier  516 , and a rear end of the spring  522  abuts against the housing  101 . The planetary carrier  516  has an annular step located at the rear end and abutting against the cylinder  531 , such that the spring  522  pushes the cylinder  531  forwardly. 
     When the impact electric hammer  100  is working under normal load, the planetary carrier  516  drives the cylinder  531  to rotate via the transmission sleeve  521 . When the impact electric hammer  100  is overloaded, the cylinder  531  and the transmission sleeve  521  stop rotating, and the planetary carrier  516  overcomes a pressure of the spring  522  and disengages from the engagement of the transmission sleeve  521 . In this way, transmission of the motor  1  may be separated from rotation of the cylinder  531  when the electric impact hammer  100  is overloaded, preventing the motor from burning. 
     As shown in  FIGS.  1  and  3   , the rotating sleeve assembly  54  includes a rotating sleeve  541 , an output gear  542  fixed on the rotating sleeve  541 , and a clamping assembly  543  fixed on the rotating sleeve  541 . The rotating sleeve  541  is arranged on the front end of the housing  101  and is perpendicular to the cylinder  531 . The clamping assembly  543  is configured to clamp the chisel head. The output gear  542  is fixed on an upper end of the rotating sleeve  541  and engaged with the input gear  532 , the input gear  532  drives the rotating sleeve  541  to rotate together with the input gear  532  via the output gear  542 . 
     As shown in  FIGS.  1  to  5   , the impact assembly  20  includes a piston  21 , a plurality of steel balls  21   a,  a hammer  22 , an impact rod  23 , a lock hammer assembly  24 , a corner support assembly  25 , and the above-mentioned cylinder  531 . The piston  21 , the hammer  22 , and the lock hammer assembly  24  are arranged on the inner wall of the cylinder  531  successively from the rear to the front of the cylinder  531 . The piston  21  defines an accommodating groove, which is running through a rear end surface of the piston  21 , and a pair of through holes, which are communicating with the accommodating groove and running through an outer periphery of the piston  21 . Meanwhile, a part of each steel ball  21   a  is accommodated in the corresponding through hole. 
     The front end of the output shaft  511  is inserted into the accommodating groove, and the output shaft  511  defines a corrugated groove  511   c  disposed on the outer periphery of the front end of the output shaft  511 . The corrugated groove  511   c  is connected end to end along the output periphery of the shaft  511  and has an axial front end and an axial rear end. The other part of each steel ball  21   a  is accommodated in the corrugated groove  511   c.  The piston  21  is clamped in the corrugated groove  511   c  by the steel ball  21   a  and can slide between the axial front end and the axial rear end of the corrugated groove  511   c.  One of an outer wall of the piston  21  and the inner wall of the cylinder  531  defines a slot, and the other of the outer wall of the piston  21  and the inner wall of the cylinder  531  is provided with a protrusion clamped in the slot, so that the piston  21  and the cylinder  531  rotate synchronously. 
     Reference to  FIGS.  9  to  10   , in this embodiment, the inner wall of the cylinder  531  defines a pair of slots  531   a  extending axially and forwardly from the rear end of the inner wall of the cylinder  531 . The outer periphery of the piston  21  is provided with a pair of protrusions  21   b,  and each of the pair of protrusions  21   b  engages with one of the pair of slots  531   a.  The piston  21  is clamped in the cylinder  531  by the protrusions  21   b  and rotates synchronously with the cylinder  531 . Each protrusion  21   b  is further a ball accommodated in the through hole of the piston  21 . A lower end of each protrusion  21   b  abuts against the corresponding steel ball  21   a,  and an upper end of the protrusion  21   b  is accommodated in the corresponding slot  531   a.  In the present embodiment, the ball is clamped by the corresponding slot  531   a,  and a rolling friction is generated instead of a sliding friction, allowing wear on the cylinder  531  to be reduced. 
     A rotation speed of the output shaft  511  is set to be S 1 , the planetary gear assembly  51  decelerates the rotation speed S 1  of the output shaft  511  to obtain a rotation speed S 2  of the planetary carrier  516  and the cylinder  531 , and the rotation speed S 1  is greater than the rotation speed S 2 . A speed difference between the rotation speed of the output shaft  511  and the rotation speed of the cylinder  531  causes the corrugated groove  511   c  on the output shaft  511  to continuously drive the piston  21  to reciprocate, such that the piston  21  compresses the air to drive the hammer  22  to impact. 
     The hammer  22  transmits the impact force to the impact rod  23 , and the impact rod  23  drives the chisel head to perform the impact output. 
     In the present embodiment, the piston  21  has a sliding portion abutting against the inner wall of the cylinder  531 , the sliding portion defines an annular groove  21   c  recessed inwardly, and the impact assembly  20  is provided with a sealing ring received in the annular groove. The sealing ring abuts against the inner wall of the cylinder to increase air tightness. The protrusion  21   b  and the slot  531   a  are both located on a rear side of the sealing ring and the annular groove  21   c  when the piston  21  is at the rearmost end of the a moving trace of the piston  21 , preventing the compressed air from leaking out of the slot, such that better air tightness is achieved, and the impact force of the electric impact hammer  100  is increased. 
     The cylinder  531  is provided with a step, which is protruding inward from the inner wall of the front end, and an elastic collar, which is located at the rear side of the step and retained in the inner wall. The lock hammer assembly  24  is axially limited between the step and the elastic collar. The lock hammer assembly  24  includes a front washer  241  abutting against the step, a rear washer  242  abutting against the elastic collar, and a rubber ring  243  disposed between the front washer  241  and the rear washer  242 . The hammer  22  has a large-diameter portion abutting against the inner wall of the cylinder  531  and a small-diameter portion located at the front end of the large-diameter portion and configured to impact the impact rod  23 . The front end of the small-diameter portion is provided with an annular protrusion, a diameter of the protrusion is larger than an inner diameter of the rubber ring  243 . When the electric impact hammer  100  is in an unloaded state, the piston  21  drives the hammer  22  to move forwardly, and the annular protrusion is clamped at the front end of the rubber ring  243  and can no longer slide backwardly. 
     As shown in  FIG.  3   , the impact rod  23  is arc-shaped and reciprocates along the front -rear direction between the cylinder  531  and the rotating sleeve  541 . The corner support assembly  25  sleeves the impact rod  23  and is supported in the housing  101 . The corner support assembly  25  includes a support sleeve  251  in the shape of an arc tube, a damping ring  252 , and a sliding sleeve  253 . The support sleeve  251  is directly supported in the housing  101 . The rear end of the support sleeve  251  abuts against a front washer  241 , and the front end of the support sleeve  251  abuts against the housing  101 . That is, the support sleeve  251  abuts on the cylinder  531  via the lock hammer assembly  24 . 
     The damping ring  252  is fixed on the inner wall of the support sleeve  251  and extends along the arc-shaped inner wall of the support sleeve  251 . The inner wall of the support sleeve  251  is provided with a blocking wall that protrudes inwardly and abuts against the rear end of the damping ring  252  to prevent the damping ring  252  from sliding to the rear end of the support sleeve  251 . The sliding sleeve  253  is fixedly held in the damping ring  252 , the sliding sleeve  253  sleeves the impact rod  23 , and the impact rod  23  slides clockwise or counter-clockwise along the inner wall of the sliding sleeve  253 . When the small-diameter portion of the hammer  22  impacts the impact rod  23 , the impact rod  23  slides clockwise along the inner wall of the sliding sleeve  253 , the rear end of the impact rod  23  is intermittently inserted into the cylinder  531 , and the front end of the impact rod  23  is intermittently inserted into the rotary sleeve  541  to impact the chisel head. 
     The impact rod  23  is provided with a convex part  23   a  protruding outwardly from a periphery of the front end of the convex part  23   a.  When the impact rod  23  slides counter-clockwise, the convex portion  23   a  is clamped in the end surface of the sliding sleeve  253  and does not contact the damping ring  252 . The convex portion  23   a  transmits a reverse impact force of the impact rod  23  to the sliding sleeve  253 . The shock-absorbing ring  252  is an arc-shaped rubber sleeve, and the damping ring  252  buffers the impact force applied on the sliding sleeve  253  and transfers the impact force to the support sleeve  251 . That is, the damping ring  252  performs a first-stage shocking absorption. 
     The support sleeve  251  transmits the impact force to the front washer  241 , and the impact force on the front washer  241  is buffered by the rubber ring  24  and then transferred to the rear washer  242 . Further, the rear washer  242  transmits the impact force to the cylinder  531  via the elastic collar. That is, the rubber ring  24  performs a second-stage shocking absorption. The rear end of the planetary carrier  516  is provided with an annular step abutting against the cylinder  531 , and the cylinder  531  transmits the impact force to the planetary carrier  516 , the spring  522  buffers the impact force transmitted to the planetary carrier  516  and then transmits the impact force to the housing  101 . That is, the spring  522  performs a third-stage shocking absorption. 
     In the present embodiment, the reverse impact force of the impact rod  23  may be buffered by three stages shocking absorption cumulatively, such that the impact electric hammer  100  may be operated more comfortably. In other embodiments, the third-stage shocking absorption may alternatively achieved by arranging a clamp spring in the front end of the planetary carrier  516 . The clamp spring is clamped on the outer ring of the cylinder  531 , and the cylinder  531  transmits the impact force to the planetary carrier  516  via the clamp spring, such that the spring  522  buffers the impact force of the planetary carrier  516  and transfers the impact force to the housing  101 . In another manner, the support sleeve  251  may be omitted, and the damping ring  252  may be directly supported in the housing  101 , and the damping ring  252  m directly abut against the front washer  241 . 
     In the present disclosure, the output shaft  511  of the electric impact hammer  100  is inserted into the accommodating groove of the piston  21 , the outer periphery of the piston  21  defines a pair of through holes running through the outer periphery and reaching the accommodating groove. The outer periphery of the front end of the output shaft  511  defines the corrugated groove  511   c,  the steel ball  21   a  is clamped between the through hole and the corrugated groove  511   c.  The steel ball  21   a  moves between the axial front end and the axial rear end of the corrugated groove  511   c  when the output shaft is rotating, such that the steel ball  21   a  drives the piston  21  to reciprocate in the axial direction. The mechanism configured to drive the piston  21  to reciprocate is concentratively arranged inside the piston  21 , such that the electric impact hammer  100  has a compact and miniaturized structure. In addition, the traditional crank connecting rod and the pendulum rod bearing having a large weight are omitted in the present disclosure, the weight of the electric impact hammer  100  is reduced significantly. 
     The output shaft  511  is in transmitted connection to the front of the motor  1 , the output shaft  511  is connected with the planetary carrier  516 , the planetary carrier  516  sleeves the rear end of the cylinder  531 , and the output shaft  511  runs through the planetary carrier  516  and drives the planetary carrier  516  to drive the cylinder  531  to rotate synchronously. The motor  1 , the output shaft  511 , and the cylinder  531  have a same axis of rotation, which makes the structure of the hammer  100  more compact and miniaturized. The impact electric hammer  100  becomes more compact, and the housing  101  can also be configured into a sleeve shape that is convenient for the operator to hold, changing the way that a handle of the impact hammer must be held from the rear end of the impact electric hammer  100 . 
     The damping ring  252  retained in the corner support assembly  25 , the rubber ring  243  of the lock hammer assembly  24  retained in the front end of the cylinder  531 , and the spring  522  sleeving the outer periphery of the cylinder  531  accumulatively performs three stages of shocking absorption, effectively reducing the vibration of the impact electric hammer  100  and improving the operating comfort of the operator. At the same time, hard collision applied to internal components of the electric impact hammer  100  may be reduced, and the service life of the electric impact hammer  100  may be increased. 
     Although the present invention has been described with reference to particular embodiments, it is not to be construed as being limited thereto. Various alterations and modifications can be made to the embodiments without in any way departing from the scope or spirit of the present invention as defined in the appended claims.