EP4650110A1 - Striking mechanism arrangement with a gear housing for receiving a striking unit - Google Patents

Abstract

Impact mechanism arrangement for a drill or chisel hammer with a gearbox housing (1) for receiving a pneumatic impact unit (2), comprising an exciter piston (8) arranged linearly alternating in a guide tube (5) by means of an eccentric unit (6) with connecting rod (7), wherein the one-piece gearbox housing (1) consists of a cylinder section (14) for accommodating the guide tube (5) and a console section (15) adjoining it in the longitudinal direction for mounting the eccentric unit (6), wherein a mounting surface (16) of the console section (15) provided for this purpose is arranged radially spaced from the central axis (X _z ) of the cylinder section (14).

Description

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.

State of the art

From the DE 10 2009 008 190 A1 A percussion mechanism of this type is described, 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.

To assemble such a percussion mechanism, 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.

It is therefore the object of the present invention to further improve a percussion arrangement of the generic type in such a way that it can be easily assembled within a short time by means of an assembly-friendly design.

Disclosure of the invention

The problem is solved starting from a percussion mechanism according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims describe advantageous embodiments of the invention. 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. This eliminates the conventional step-by-step assembly, in which the eccentric unit is mounted with the exciter piston and connecting rod after the guide tube has been inserted. Pre-assembly, on the other hand, 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.

According to a further improvement of the invention, it is proposed that 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. Alternatively, 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.

According to a preferred embodiment, 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.

According to a preferred embodiment, 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. Thus, 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.

According to a preferred embodiment of 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.

To securely position the guide tube of the impact mechanism unit within the cylindrical section of the gearbox housing, 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.

To protect the impact mechanism from the ingress of dirt and moisture, a further improvement proposes that 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.

Detailed description based on drawing

• Fig. 1 eine Längsschnittdarstellung einer in einem Getriebegehäuse montierten Schlagwerkseinheit eines Meißelhammers,
• Fig. 2 eine perspektivische Ansicht eines Getriebegehäuses mit Schlagwerkseinheit vor der Montage,
• Fig. 3 eine Explosionsdarstellung einer Schlagwerkseinheit,
• Fig. 4 eine perspektivische Darstellung eines Getriebegehäuses mit Schlagwerkseinheit während der Montage,
• Fig. 5 eine perspektivische Darstellung eines Getriebegehäuses mit Schlagwerkseinheit bei eingeführtem Führungsrohr,
• Fig. 6 eine perspektivische Darstellung eines Getriebegehäuses mit Schlagwerkseinheit vor der lösbaren Befestigung, und
• Fig. 7 eine perspektivische Explosionsdarstellung der Schlagwerksanordnung mit weiteren Anbauteilen.

Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. The figures show:

• Fig. 1 a longitudinal section view of a percussion unit of a chisel hammer mounted in a gearbox housing,
• Fig. 2 a perspective view of a gearbox housing with impact mechanism unit before assembly,
• Fig. 3 an exploded view of a percussion unit,
• Fig. 4 a perspective view of a gearbox housing with impact mechanism unit during assembly,
• Fig. 5 a perspective view of a gearbox housing with impact mechanism unit with guide tube inserted,
• Fig. 6 a perspective view of a gearbox housing with impact mechanism unit in front of the detachable mounting, and
• Fig. 7 A perspective exploded view of the percussion mechanism with additional attachments.

According to Fig. 1 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.

According to Fig. 2 The one-piece gearbox housing 1 according to the invention 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. For this purpose, 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.

In this embodiment, 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.

According to Fig. 3 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. To attach the impact unit 2 to the gearbox housing (not shown here) in its assembled state, the guide tube 5 has an outer flange 18 for the attachment of a screw.

From the Fig. 4 It is evident that the central axis X _F of the guide tube 5 of the impact unit 2 is offset by a radial distance s relative to the central axis X _Z of the cylinder section 14 of the gearbox housing 1, in order to be able to insert the impact unit 2 into the gearbox housing 1 despite the drive transmission means protruding from the console section 15.

In the 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.

According to Fig. 6 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.

After 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 invention is not limited to the exemplary embodiment described above. Rather, variations thereof are also conceivable and are included within the scope of protection of the following claims. In particular, 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.

Reference symbol list

1

gearbox housing

2

Percussion unit

3

Tool holder unit

4

Döpper

5

Guide tube

6

Eccentric unit

7

connecting rod

8

Excitation piston

9

Piston

10

eccentric

11

Eccentric bearing pin

12

gear

13

Motor pinion

14

Cylinder section

15

Console section

16

Mounting surface

17

Warehouse opening

18

flange

19

Guided tour

20

screw

21

Housing cover

XZ

central axis of the cylinder section

XF

central axis of the guide tube

s

radial distance between the axes

Claims (10)

Impact mechanism arrangement for a drill or chisel hammer with a gearbox housing (1) for receiving a pneumatic impact unit (2), comprising an exciter piston (8) arranged linearly alternating in a guide tube (5) by means of an eccentric unit (6) with connecting rod (7), characterized in that the one-piece gearbox housing (1) consists of a cylinder section (14) for accommodating the guide tube (5) and a console section (15) adjoining it in the longitudinal direction for mounting the eccentric unit (6), wherein a mounting surface (16) of the console section (15) provided for this purpose is arranged radially spaced from the central axis (X _Z ) of the cylinder section (14). Percussion arrangement according to claim 1,
characterized in that the inner diameter of the cylinder section (14) of the gearbox housing (1) is dimensioned so large that the guide tube (5) can be mounted taking into account at least one drive transmission means projecting from the mounting surface (16). Percussion arrangement according to claim 2,
characterized in that the drive transmission means is designed as a motor pinion (13) of a drive motor which engages with a gear (12) of the eccentric unit (6). Percussion arrangement according to claim 1,
characterized in that the mounting surface (16) has a bearing opening (17) for the rotary bearing of an eccentric bearing pin (11) of the eccentric unit (6). Percussion arrangement according to claim 3 or 4,
characterized in that, for mounting the impact mechanism unit (2) in the gearbox housing (1), the central axis (X _F ) of the guide tube (5) of the impact mechanism unit (2) can be spaced apart from the central axis (Xz) of the cylinder section (14) of the gearbox housing (1) by a radial distance (s) which corresponds at least to the length (I) of the motor pinion (13) and/or the eccentric bearing pin (11), wherein in the mounted state both central axes (X _F, X _Z ) run coaxially to each other. Percussion arrangement according to claim 1,
characterized in that the impact unit (2) is composed as a pre-assembled assembly from the guide tube (5), the eccentric unit (6) and one of the opposing flying pistons (9), wherein the guide tube (5) has an outer flange (18) for detachable attachment to the gearbox housing (1). Percussion arrangement according to one of the preceding claims,
characterized in that the distal end of the guide tube (5) engages in a guide receptacle (19) of the cylinder section (14) of the gearbox housing (1). Percussion arrangement according to one of the preceding claims,
characterized in that the eccentric unit (6) is detachably attached to the console section (15). Percussion arrangement according to one of the preceding claims,
characterized in that a housing cover (21) covering the area of the eccentric unit (6) is detachably attached to the gearbox housing (1). Drill or chisel hammer, equipped with a percussion mechanism according to one of the preceding claims.