US 3799275 A
A synthetic plastic housing of a hammer-drill has an output shaft for coupling with the drill bit, the output shaft being mounted in the housing for rotary and reciprocable displacement. A drive drives the output shaft in rotation and the inner end of the output shaft carries a disc which is normally in engagement with a juxtaposed but fixed disc, with the two discs having respectively engaging projections so configurated that when the disc on the output shaft rotates with the latter, it will alternately be urged away from and be allowed to move closer to the fixed disc so that the output shaft reciprocates axially. A cylindrical control element extends transversely of the axis of the output shaft in the region of the rear end thereof, having at least two surfaces which extend in parallelism with the axis of the cylindrical control member but are located at different distances from this axis. The control member is turnable so that, when the surface located closer to this axis is juxtaposed with the inner end of the output shaft, there is no contact with the latter, whereas when the surface which is farther from the axis of the control member is juxtaposed with the inner end of the output shaft it presses against the latter, urging the same and thereby the disc thereon away from and out of engagement with the fixed disc so that the output shaft will only rotate but not reciprocate.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Plattenhardt et al.
1 Mar. 26, 1974 HAMMER-DRILL  Inventors: Dieter Gotsch Plattenhardt;
Reinhard Hahner; Hans Lederer; Manfred Kim, all of Stuttgart; Gerhard Kuhlmann, Stuttgart-Feuerbach, all of Germany  Assignee: Robert Bosch GmbH, Stuttgart,
Germany  Filed: Jan. 13, 1972 [211 Appl. No.: 217,579 I Primary Examiner-Werner H. Schroeder Attorney, Agent, or Firm-Michael S. Striker  ABSTRACT A synthetic plastic housing of a hammer-drill has an output shaft for coupling with the drill bit, the output shaft being mounted in the-housing for rotary and reciprocable displacement. A drive drives the output shaft in rotation and the inner end of the output shaft carries a disc which is normally in engagement with a juxtaposed but fixed disc, with the two discs having respectively engaging projections so configurated that when the disc on the output shaft rotates with the latter, it will alternately be urged away from and be allowed to move closer to the fixed disc so that the output shaft reciprocates axially. A cylindrical control e1- ement extends transversely of the axis of the output shaft in the region of the rear end thereof, having at least two surfaces which extend in parallelism with the axis of the cylindrical control member but are located at different distances from this axis. The control member is turnable so that, when the surface located closer to this axis is juxtaposed with the inner end of the output shaft, there is no contact with the latter, whereas when the surface which is farther from the axis of the control member is juxtaposed with the inner end of the output shaft it presses against the latter, urging the same and thereby the disc thereon away from and out of engagement with the fixed disc so that the output shaft will only rotate but not reciprocate.
6 Claims, 3 Drawing Figures  Foreign Application Priority Data Feb. 5, 1971 Germany 2105335  US. Cl. 173/48  Int. Cl. E2lc 3/32  Field of Search 173/13, 47, 48, 29, 104, 173/105, 109; 74/22  References Cited UNITED STATES PATENTS 3,693,728 9/1972 Stroezel 173/48 X 3,123,156 3/1964 Gapstur... 173/48 3,171,286 3/1965 Stewart ,1 173/48 X FOREIGN PATENTS OR APPLICATIONS 432,338 3/1967 Switzerland 173/13 684,169 4/1964 Canada .1 173/48 1,457,220 9/1966 France 173/47 1.5 50 47 36 3,5 1.9, 251. 2 1.7 48 12,7. ti 13 7 15 .ll f 33 37 V 1 If 37 L1.
HAMMER-DRILL BACKGROUND OF THE INVENTION The present invention relates to a tool, and more particularly to a portable tool. Still more particularly, the invention relates to a drill and in particular to a socalled hammer-drill.
The category of tool known as a hammer-drill provides for a two-fold possibility of operation. On the one hand it operates in the manner of an ordinary tool in that its output shaft which is to be coupled with the drill bit is rotated by a suitable drive in conventional manner. On the other hand, however, a reciprocatory motion can be imparted upon on the output shaft so that successive blows are transmitted to the drill bit while the same is being rotated. It is known to provide hammer-drills in which the rotation and reciprocation are necessarily coupled, that is in which it is impossible to use the drill only to rotate the drill bit but not to impart impacts on the same. It is also known, however, to provide hammer-drills in which the drill bit can be rotated without having impacts imparted thereto and in which suitable means are provided for selectively superimposing the reciprocatory motion of the output shaft on the rotary motion thereof, so that impacts are transmitted via the output shaft to the drill bit only if and when desired in addition tothe rotation thereof.
Such hammer-drills, particularly the last-mentioned type, have become highly popular especially among the do it yourself" purchasers. They are of handy dimensions and can be used not only for drilling purposes in a great variety of different materials, but can also be used to drive auxiliary components, for instance sanders, circular saws and the like. Of course, this is possible only if the hammer-drill is of the type in which the possibility exists to select purely a rotational movement, that is in which the reciprocatory movement intended to impart impacts to the output shaft, can be selectively switched on and off.
The problem with the known constructions of the prior art is that the means for effecting such switching on and off is not entirely satisfactory. In particular such known hammer-drills utilize a metallic sleeve which surrounds the output shaft or spindle-within the housing neck journalling the same, over a portion of the length of the output shaft and is provided with a flange projecting beyond the neck at the exterior of the housing. In order to switch the hammer-drill from purely rotational operation to a mode of operation in which reciprocatory motion (impacts) is superimposed upon the rotational motion, this metallic flange is engaged by the hand of the user and is turned. The difficulty with this type of construction is that there exists the possiblity of inadvertent contact of the flange by a part of the users anatomy, for instance a hand. Conventionally such hammer-drills are held and gripped by the right hand of the user and are supported with the left hand, and it is a quite frequent occurrence that the left hand thus contacts the metallic flange. If, under these circumstances, the device is for instance used to drill into a wall and the drill bit should contact a live electrical wire embedded in the wall, the danger of electrocution of the user is considerable if the user inadvertently contacts the exposed flange.
On the other hand, when a hammer-drill of this type is to be used to drive auxiliary devices, such as saber saws, oscillatory sanders, circular saws, hedge shears or the like, then the neck of the housing is inserted into a receptacle provided for this purpose in the auxiliary device and is fixed therein. Such a procedure is made difficult by the presence of the aforementioned flange because this presence reduces the available length of the neck over which the latter can be gripped by the clamping means provided in the auxiliary device for this purpose. This means that the security of connection between the hammer-drill and the auxiliary device is reduced. Moreover, there is always the possibility that when the hammer-drill is connected with such a device, the user may not notice that the hammer drill is set for both rotary and reciprocatory movement of the output shaft so that, when the hammer-drill is subsequently energized, damage may possibly occur to it and/or the auxiliary device. Even if no such damage occurs, the flange is concealed and it is impossible to determine that the hammer-drill is set forth both rotary and reciprocatory operation until it is turned on, at which time the hammer-drill must be switched off again, and must be disconnected from the auxiliary device in order to change over its mode of operation to purely rotary movement, whereupon the hammer-drill must then again reconnected with the auxiliary device.
In addition to these disadvantages there is the further fact that the arrangement of the components for switching over from purely rotational operation to an operation in which reciprocatory motion is superimposed upon the rotational motion, in the neck of the hammer-drill causes the impacts during hammer operation to be transmitted via the walls of the neck to the mass of the motor, particularly of the stator package. The relatively thin walls tend to yield under the impact of the blows so that the blows are less pronounced than is desirable and their effectiveness is reduced.
SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to overcome the disadvantages of the prior art.
In particular it is an object of the present invention to provide an improved hammer-drill of the type here under discussion.
More particularly still, it is an object of the invention to provide such an improved hammer-drill which can be used with less danger of injury to the operator and of damage to the drill itself.
A still further object of the invention is to provide such an improved hammer-drill in which the effectiveness of the impacts transmitted to the drill bit is increased.
Still a concomitant object of the invention is to provide such an improved hammer-drill in which the change-over between purely rotational operation and rotational operation with reciprocatory motion superimposed thereupon, is made simpler and more effective.
In pursuance of these and other objects which will become apparent hereafter, one feature of the invention resides in a hammer-drill which, briefly stated, comprises a housing and an output shaft mounted in the housing for rotary and reciprocable displacement. The output shaft has an inner end-in the housing and drive means is provided for driving the output shaft in rotation. Motion-imparting means is provided for imparting reciprocatory motion to the output shaft and includes a first disc-shaped component on the output shaft rotatable therewith and a second disc-shaped component fixedly juxtaposed with the first component normally engaged therewith. The components have cooperating projections which on rotation of the first component impart reciprocatory motion to the output shaft. Control means is provided for controlling engagement of the second component with the first component and includes a substantially cylindrical member having a longitudinal axis extending transversely of the axis of rotation of the shaft and at least one surface extending in parallelism with the longitudinal axis. The surface is adapted to exert pressure upon an inner end of the output shaft in a sense displacing the latter axially so that the first component becomes disengaged from the second component, and turning means is provided for turning the cylindrical member to and from a position in which the one surface is juxtaposed with and exerts such pressure upon the inner end of the output shaft.
To provide for a complete ambient insulation'of all components in an electrical sense, an insulating handle is provided which is accessible at the exterior of the hammer drill and operatively associated with the cylindrical member in a sense displacing the same to and from the aformentioned position, and indicia means is provided which indicates by the position of the handle how the cylindrical member is positioned that is whether the purely rotational mode of operation is selected or whether the mode of operation is selected in which the impacts on the output shaft are superimposed upon the rotary motion thereof.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially sectioned side-elevational view illustrating one embodiment of the invention;
FIG. 2 is a cross-section of FIG. 1, with parts omitted for the sake of clarity; and
FIG. 3 is a detail view of a component in FIG. 1 as seen in the direction of the arrow III therein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail it will be seen that we have illustrated a hammer-drill having a chuck 33 of conventional construction with which a drill bit can be connected. The housing of the hammer-drill has a handle 8 which is to be engaged by an operator. For the sake of convenience in the description two terms will hereafter be utilized, namely reference will be made to the output side of the device which refers to the side where the chuck 33 is located and the "input side" which refers to the side where the drive means is located such as the electromotor which is in the interior of the housing.
With this in mind it will be seen that the housing is in form of two shell-shaped sections 1 and 2 which are at least predominantly composed on synthetic plastic material. The sections 1 and2 are connected together by self-tapping slotted screws 3 and 4, with the screws being threaded into holes 5 in the section 1. These holes 5 are located in projections 6 which are connected with one another and with the wall of the section 1 by ribs 7. Similar projections and ribs are juxtaposed in the section 2 with those of the section 1.
The handle 8 or grip 8 has already been mentioned and the housing further has a motor chamber 9, a gear chamber 10 and a spindle or output shaft journal neck 11. These various parts of the housing are separated from one another by ribs 12. On the ribs provided in the shell section 1 there are provided projecting longitudinal beads 13 which engage in recesses in the similar ribs of the section 2. Similar arrangements are provided along the juxtaposed edges of the sections 1 and 2 in order to provide an appropriate sealing of the housing with respect to the exterior and of the individual chambers of the housing with reference to one another.
A suitable drive is provided, and advantageously will be in form of another motor 15 accommodated in the motor chamber 9. A stator package 16 is accommodated between the ribs 7 and a rotor 19 is press-fitted via a metallic sleeve 18 and an insulating sleeve 19 on a motor shaft 20. The end of the motor shaft 20 which faces the output side is configurated as a pinion 21 and behind the pinion 21 in the direction towards the input side the shaft 20 has a section 22 of slightly greater diameter than the remainder carrying a bearing 23. The shaft 20 is journalled in a metallic journal mount 24 with a bearing 23, the journal mount extends with its main dimension in direction normal to the elongation of the shaft 20 and is secured in the section 1 by means of screws 25 and 26 for which metallic bushings 27 are accommodated as by casting in the material of the section 1.
The journal mount 24 is provided with a recess 28 wich accommodates the bearing 23, and in parallelism with the recess 28 there is provided a recess 29 of substantially smaller diameter which is configurated as a slide bearing for receiving a drive shaft. There is in addition provided a third parallel recess 30 in which a slide bearing sleeve 31 is press-fitted, with the latter accommodating a portion 32 of the output shaft or spindle 33 both rotatively and reciprocably.
The end face 34 of the journal mount 24 which faces the output side is provided in the region of the recess 30 with a'fixed stationary disc-shaped portion 35, in this case made of one-piece with the journal mount 24. juxtaposed with this disc-shaped portion or component 35 is a similar disc-shaped component 36 which is rotatable and made of one-piece with a gear 37 which is press-fitted on the spindle 33. The spindle 33 is journalled for rotation and for reciprocation in a bearing 38 which is mounted in the neck 11 and a spring 39 urges the spindle in an and position in which a spring ring 40 of the spindle abuts against the inner race of the bearing 38 and the component 36 is out of engagement with the component 35. It will be appreciated that each of these components 35 and 36 is provided on their respectively juxtaposed surfaces with a plurality of projections (see also FIG. 3) so configurated that when the component 36 rotates with reference to the component 35 and is in contact therewith, the angular displacement of the projections of the component 36 with reference to those of the component 35 results in the imparting of successive impacts or blows upon the component 36 and via the same upon the spindle 33.
The mount 24 is further provided with a cylindrical recess 41 normal to the recesses 28, 29 and 30, and accommodating turnably a cylindrical or substantially cylindrical member 42. The spindle 33 abuts against the member 42 via the intermediary of a ball 43 which is accommodated in the portion 32.
In accordance with the invention the member 42 is provided with a surface 44 which extends in parallelism with its longitudinal axis and which, when it faces the portion 32 of the spindle 33, permits the spindle 33 to become axially displaced towards the handle or grip 8 under the urging of the spring 39 so that the components 36 engages the component 35. In this position rotation of the spindle 33 results not only in rotary movement but also in the transmission of blows upon it.
Normal to the recesses 28, 29 and 30 and to the recess 41 there are provided two recesses 45 and 46 in mount 24 which serve for the passage of screws 25 and 26.
A knurled portion 47 of the cylindrical member 42 projects from the interior of the chamber through an opening 48 into an outwardly open depression of the housing and carries for instance by press-fitting turnable knob 50 of electrically insulating synthetic plastic material or another electrically insulating material. The configuration of the knob 50 is such that it fills the recess 49 and is provided with a rib 51 serving for effecting its turning and also as an indicium, so that the angular position of the rib 51 indicates visually the position of the cylindrical member 42 and immediately makes it apparent whether the device is switched to purely rotational movement or rotational movement with reciprocatory movement superimposed.
The ribs of the sections 1 and 2 are so arranged that at the output side they contact and are supported against the mount 24, and at the input side are supported against the stator package 16, so that they can transmit impacts to the stator package which are originated by relative angular displacement of the components 34 and 36, and thereby transmitted to the mount 24.
It will be understood that each of the elements described above or two or more together may also find a useful application in other types of constructions differing'from the types described above.
While the invention has been illustrated and described as embodied in a hammer-drill, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What is claimed as new and desired to be protected by letters Patent is set forth in the appended claims.
K. A hammer-drill, comprising an at least predominantly synthetic plastic housing; ajournal mount in said housing; an output shaft journalled in said mount for rotary and reciprocable displacement and having an inner end located in said housing; drive means in said housing and having a drive shaft journalled in said mount and operative for driving said output shaft in rotation; motion-imparting means for imparting reciprocatory motion to said output shaft, including a first disc-shaped component on said output shaft rotatable therewith, and a second disc-shaped component fixedly juxtaposed with said first component and normally engaged therewith, said components having cooperating projections which on rotation of said first component impart reciprocatory motion to said output shaft, said output shaft, motion-imparting means and second component all being mounted on said journal mount; and control means for controlling the engagement of said second component with said first component, including a substantially cylindrical member turnably journalled in said mount and having a longitudinal axis extending transversely of the axis of rotation of said shaft and having at least one surface extending in parallelism with said longitudinal axis and being adapted to exert pressure upon said inner end of said output shaft in a sense displacing the latter axially so that said first component becomes disengaged from said second component, and turning means for turning said cylindrical member to and from a position in which said one surface is juxtaposed with and exerts such pressure upon said inner end.
2. A hammer-drill as defined in claim 1, said cylindrical member further having an additional surface also extending in parallelism with said longitudinal axis but spaced therefrom by a lesser distance than the firstmentioned surface so that, when said additional surface is juxtaposed with said inner end, it is spaced therefrom and said first and second components are in engagement with one another.
3. A hammer-drill as defined in claim 1, said housing having two interior compartments, one of which houses said drive means and the other of which houses at least said output shaft and components; said journal mount being mounted between said compartments.
4. A hammer-drill as defined in claim I, said turning means including an electrically insulated handle operatively associated with said cylindrical member and accessible at the exterior of said housing.
5. A hammer-drill as defined in claim 4, said handle including indicia means providing a visual indication of the position of said cylindrical member.
6. A hammer-drill as defined in claim 1, said housing including two cooperating shell-shaped housing sections.