Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D17/06—Hammer pistons; Anvils ; Guide-sleeves for pistons
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D11/00—Portable percussive tools with electromotor or other motor drive
  • B25D11/06—Means for driving the impulse member
  • B25D11/12—Means for driving the impulse member comprising a crank mechanism
  • B25D11/125—Means for driving the impulse member comprising a crank mechanism with a fluid cushion between the crank drive and the striking body
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2217/00—Details of, or accessories for, portable power-driven percussive tools
  • B25D2217/0011—Details of anvils, guide-sleeves or pistons
  • B25D2217/0019—Guide-sleeves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
  • B25D2250/065—Details regarding assembling of the tool
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
  • B25D2250/121—Housing details
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
  • B25D2250/231—Sleeve details
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
  • B25D2250/245—Spatial arrangement of components of the tool relative to each other

Definitions

• the present invention relates to an impact mechanism arrangement for a drill or chisel hammer with a gearbox housing for receiving a pneumatic impact mechanism unit, comprising an exciter piston arranged linearly alternating in a guide tube by means of an eccentric unit with connecting rod.
• the application area of the invention extends primarily to handheld drills or chisels of higher power, which are equipped with a pneumatic impact unit for applying an alternating linear drive energy to an impact drill or chisel.
• a percussion mechanism of this type comprising a pneumatic percussion mechanism with a free piston movable along a striking axis, a striking surface limiting the movement of the free piston along the striking axis in the direction of the strike, an exciter piston limiting the movement of the free piston along the striking axis opposite to the direction of the strike, and a pneumatic space between the free piston and the exciter piston.
• a drive mechanism serves to periodically move the exciter piston with a linear stroke along the striking axis, thereby exciting the free piston to a linearly alternating movement between the striking surface and a minimal approach to the exciter piston.
• This pneumatic impact unit is installed in a gearbox housing of an electrically operated chisel hammer, with the guide tube inserted into a gearbox housing. It is pressed in. In contrast, the eccentric unit is only indirectly connected to the gearbox housing.
• the guide tube along with the exciter piston and the pre-assembled connecting rod, must be inserted into the gearbox housing without any play.
• the eccentric unit with its eccentric pin, is then mounted into the connecting rod's eye. Because the connecting rod is rotatable within the exciter piston, the exciter piston within the guide tube, and the eccentric itself, the axes of the eccentric pin and the connecting rod eye are not normally aligned. These axes must therefore be actively aligned during assembly. Finally, the eccentric unit must be securely fastened to the gearbox housing.
• the assembly process for the striking mechanism unit is therefore quite cumbersome.
• the components require tight manufacturing tolerances to ensure correct assembly.
• Claim 10 relates to a drill or chisel hammer with a percussion mechanism designed according to the invention.
• the invention includes the technical teaching that a one-piece gearbox housing is used, which consists of a cylindrical section for accommodating the guide tube and a console section adjoining it in the longitudinal direction for mounting the eccentric unit, wherein a mounting surface of the console section provided for this purpose is arranged radially spaced from the central axis of the cylindrical section.
• the advantage of the solution according to the invention lies particularly in the fact that the impact mechanism unit can be pre-assembled as a single unit and then inserted as a whole into the one-piece gearbox housing according to the invention and attached thereto.
• Pre-assembly facilitates its insertion into the gearbox housing of the rotary hammer. Thanks to the functionally integrated design of the gearbox housing with its cylinder section and bracket section, the number of components is reduced. Furthermore, a conventional gearbox housing flange, which typically represents a design weakness and therefore requires dimensioning with screws and material accumulations, is no longer necessary. Since, according to the invention, there is no separation of the housing in the load path, enormous potential for lightweight construction is unlocked.
• the inner diameter of the cylindrical section of the gearbox housing be dimensioned so large that the guide tube can be mounted taking into account at least one drive transmission element protruding from the mounting surface.
• the guide tube can also be sufficiently bulged on one side to allow a pre-assembled impact unit to be inserted into the cylindrical section of the gearbox housing despite the protruding drive transmission element on the mounting surface.
• the one-piece gearbox housing designed according to the invention thus provides the prerequisite for being able to insert all components used for impact generation, in the form of a pre-assembled impact unit, into the end face facing away from the tool, since the gearbox housing offers sufficient installation space to also connect transversely extending drive transmission elements to the eccentric unit.
• the drive transmission means is designed as a motor pinion of a drive motor, which engages in a toothed ring of the eccentric assembly for rotary drive.
• the mounting surface of the gearbox housing may also have a bearing opening for the rotary bearing of an eccentric bearing pin of the eccentric unit.
• the eccentric bearing pin forms the axis of rotation of the eccentric and is preferably rotatably mounted on the gearbox housing via a rolling bearing, for example with a needle bearing.
• the inner diameter of the gearbox housing is designed to be larger than the outer diameter of the guide tube of the impact mechanism unit such that the central axis XF of the guide tube of the impact mechanism unit is spaced radially apart from the central axis XZ of the cylindrical section of the gearbox housing by a distance s that corresponds at least to the length of the motor pinion and/or the eccentric bearing journal, wherein, in the assembled state, both central axes XF and XZ are coaxially aligned.
• the lengths of the drive power transmission components projecting from the mounting surface or the eccentric unit determine the installation space that must be provided by the inner diameter of the gearbox housing. Conversely, this space can be reduced by dimensioning the lengths of the corresponding drive transmission elements to be as short as possible.
• the impact mechanism unit as a pre-assembled module, it is proposed that its guide tube has an outer flange, preferably welded on, for detachable fastening to the gearbox housing.
• the detachable fastening is preferably carried out using several screws.
• a further improvement to the invention proposes that the distal end of the guide tube engage in a guide recess of the cylindrical section of the gearbox housing.
• This guide recess therefore has a smaller diameter than the remaining inner diameter of the cylindrical section to ensure a proper fit with the distal end of the guide tube.
• the eccentric unit is also preferably detachably attached to the gearbox housing, specifically to its console section. This detachable attachment is also preferably achieved using several screws.
• a housing cover covering the eccentric unit be detachably attached to the gearbox housing, which can also be done by means of screws. This closes the mounting opening between the cylinder section of the gearbox housing and the console section, so that the impact mechanism is completely enclosed within the gearbox housing.
• a percussion mechanism for an exemplary chisel hammer essentially consists of a gearbox housing 1 for accommodating a pneumatic percussion unit 2 and a tool holder unit 3 for a - not shown here - chisel.
• a drive force-transmitting so-called dopper 4 is arranged to move linearly and alternately between the pneumatic impact unit 2 and the tool holding unit 3.
• the pneumatic percussion unit 2 essentially consists of an exciter piston 8 arranged linearly and alternately in a guide tube 5 by means of an eccentric unit 6 with connecting rod 7.
• the exciter piston 8, in conjunction with the guide tube 5, corresponds to an opposing free piston 9, which comes into contact with the striker 4 in order to impart the pneumatically damped blows generated in the percussion unit 2.
• the eccentric unit 6 comprises an eccentric 10 with a housing-side mounted eccentric bearing pin 11.
• the eccentric unit 6 is driven via a gear stage with a gear 12 arranged coaxially to the eccentric bearing pin 11, which engages with a drive motor (not shown here) via its motor pinion 13.
• the one-piece gearbox housing 1 is composed of a cylindrical section 14 and a console section 15 integrally formed therewith.
• the cylindrical section 14 serves to house the guide tube 5 of the impact unit 2, whereas the console section 15, which adjoins it longitudinally, is provided for mounting the eccentric unit 6 of the impact unit 2.
• the console section 15 has a mounting surface 16, which is arranged radially spaced from the central axis of the cylindrical section 14.
• the inner diameter of the cylindrical section 14 of the gearbox housing 1 is much larger than the outer diameter of the guide tube 5 to be housed therein, in order to allow the pre-assembled impact unit 2 to be inserted into the cylindrical section 14 of the gearbox housing 1, taking into account the drive transmission means projecting from the mounting surface 16.
• the primary drive transmission means is the motor pinion 13 of the drive motor. Adjacent to this, the mounting surface 16 has a Bearing opening 17 for the rotary bearing of the aforementioned eccentric bearing pin of the eccentric unit 6.
• the pre-assembled pneumatic impact unit 2 consists of the guide tube 5 with an exciter piston 8 and a free piston 9 assigned to each end, the connecting rod 7 being articulated to the exciter piston 8 and driven via the eccentric 10 of the eccentric unit 6 to convert the rotary drive movement into an alternating linear movement for actuating the impact unit 2.
• the guide tube 5 has an outer flange 18 for the attachment of a screw.
• Fig. 5 In the illustrated assembled state of the percussion unit 2 in the gearbox housing 1, the two central axes X F and Xz of the respective components are in coaxial alignment.
• the distal end of the guide tube 5 engages in a guide receptacle 19 of the gearbox housing 1.
• the guide receptacle 19 thus forms a fit with the guide tube 5.
• the impact unit 2 is detachably attached to the gearbox housing 1 by providing several screws 20a for screwing the eccentric unit 6 to the console section 15, whereas several further screws 20b ensure that the guide tube 5 is screwed to the housing 1 via its flange 18, so that all movable components are fixed in position.
• FIG. 7 A housing cover 21 is provided in the area of the eccentric unit 6, which is also detachably attached to the gearbox housing 1 via a screw connection in order to protect the internal impact unit 2 from dirt and moisture.
• the parting line runs towards the housing cover 21. diagonally opposite the rotation axis of the eccentric unit 6 and the longitudinal axis of the guide tube 5, in order to create an access that ensures easy and quick assembly of the pre-assembled impact unit 2.
• the solution according to the invention eliminates a connection in the load path of the gearbox housing, which can therefore also be designed as a lightweight metal housing. Dynamic loads are supported against inertia.
• a one-piece gearbox housing makes it possible to dispense with a highly stressed bolted connection and the associated concentration of load paths on individual bolts.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Percussive Tools And Related Accessories (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=91129607

Family Applications (1)

Country Status (2)

Citations (4)

• 2024
  • 2024-05-15 EP EP24175882.0A patent/EP4650110A1/fr active Pending
• 2025
  • 2025-05-02 WO PCT/EP2025/062088 patent/WO2025237701A1/fr active Pending

Patent Citations (4)

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