Patent Application
20090145620
1. Field of the Invention
The present invention relates to a hand-held power tool for at least percussively driving a working tool along a percussion axis and including a chuck, in particular, to hammer drill or chisel hammer.
2. Description of the Prior Art
Usually, in percussion hand-held power tools with an optionally rotatable, drive spindle, a chuck is secured on the spindle or, according to German Publication DE 37 20 512, is formed directly thereon.
In the chuck according to German Publication DE 37 20 512, a shank of a working tool, which is received in the receiving sleeve, has elongate locking grooves which are closed at both their axial sides and into which a radially displaceable locking member radially engages. The elongate locking grooves in cooperation with the locking member provide for a limited axial displacement of the working tool shank and, thereby, of the working tool. The shank is connected with the receiving sleeve for joint rotation therewith by axially and extending radially inwardly rotation-transmitting webs which are provided on the inner surface of the receiving sleeve and which engage in associated rotation-transmitting grooves provided on the shank. A percussion piston, which is driven by a pneumatic percussion mechanism applies blows to an axially displaceably supported anvil that, in turn, applies blows to the power tool side end surface of the shank.
European Publication EP 1 604 763 discloses a percussion hand-held power tool in which a one-piece pot-shaped anvil, which is open at its working tool side, is mounted on the drive spindle for joint rotation therewith and for a limited axial displacement relative thereto. The shank of the working tool is secured in the anvil again for joint rotation therewith and for a limited relative displacement relative thereto. The shank is flushed by a flushing liquid before the flushing liquid penetrates, at the end side, in the flushing bore of the working tool. The flushing fluid and seals, which are arranged between the movable parts, prevent penetration of abrasive dust to a most possible extent. This solution, which is optimal for a mining operation is not suitable for a dry standard use in the constructional industry. U.S. Pat. No. 4,184,692 discloses a chuck of a power drill and connected with the drive spindle and in which a cylindrical shank of a drill, which is received in the chuck, is provided with a spherical dimple in which a radially displaceable locking ball engages for securing the shank and, thereby, the drill in the chuck against axial and rotational displacements relative to the chuck.
An object of the present invention is a percussion hand-held power tool having a chuck with which penetration of dust is prevented to a most possible extent.
Another object of the invention is a dust-tight chuck for a percussion hand-held power tool.
A further object of the present invention is to provide a working tool insertable in the inventive chuck.
These and other objects of the present invention, which will become apparent hereinafter are achieved by providing a hand-held power tool for at least percussively driving a working tool along a percussion axis and including a chuck for receiving the working tool and having a receiving sleeve fixedly connected with the chuck for joint rotation therewith and for limited axial displacement relative thereto and open at least at one of its opposite ends, at least one locking member radially displaceably supported in the receiving sleeve for axially securing therein a shank of the working tool insertable in to the receiving sleeve, and an axially extending anvil securable in the receiving sleeve for closing a power tool side end of the receiving sleeve.
With an anvil closing the power tool side end of the receiving sleeve, both the receiving sleeve and the anvil are closed together in a pot-shaped manner. This prevents penetration of dust in the interior of the power tool.
Advantageously, the anvil is fixedly secured in the receiving sleeve by interference fit, e.g., by being shrinked, or by material-locking connection with glue, soldering, e.g. Thereby a rigidly assembled body can be produced technologically easy.
Alternatively, the anvil can be elastically secured in the receiving sleeve by an elastic intermediate layer, e.g., by vulcanization. Thereby, the blow pulses applied to the free end of the anvil are decoupled from the receiving sleeve to a most possible extent and, thereby, almost completely transmitted to the working tool.
According to another alternative, the anvil and the receiving sleeve are formed as a one-piece part of a common workpiece of a same material. Thereby the one-piece part can be economically and simply produced by, e.g., stamping.
Advantageously, the working tool side end surface of the anvil is spherical, whereby a position-tolerant control pulse can be applied to the shank of the working tool which is received in the receiving sleeve.
Advantageously, the receiving sleeve forms, at its power tool side, on its radially outer surface, axially and radially extending rotation-transmitting wings engageable in correspondingly adapted, associated grooves formed in a drive spindle of the power tool. Thereby, the receiving sleeve is connected with the drive spindle for joint rotation therewith and for a limited axial displacement relative thereto.
Advantageously, the anvil forms, on its radially inner surface, axially and radially extending rotation-transmitting wings engageable in correspondingly adapted, associated grooves formed in a shank of the working tool. Thereby, the shank and, thus, the working tool is connected with the receiving sleeve for joint rotation therewith.
Advantageously, the at least one locking member, which is radially displaceably supported in the receiving sleeve for axially securing therein a shank of the working tool insertable into the receiving sleeve, is formed as a locking ball. In case the associated locking recess in the shank is formed as an elongate groove, the working tool is axially displaceable, within limits, relative to the receiving sleeve. In case the shape of the locking recess corresponds to the shape of the locking member and is formed, e.g., as a spherical cap, in case the locking member is formed as a locking ball, the working tool is axially fixed in the receiving sleeve.
Advantageously, a stop member, preferably a stop sleeve, is arranged radially outwardly of the locking member. Thereby, locking of the working tool in the receiving sleeve can be stopped.
Advantageously, there is further provided spring means for resiliently preloading stop member against the receiving sleeve. Thereby, the stop member is self-locking. Preferably, the spring means is formed as a helical spring.
Advantageously, the axially displaceable, within limits, receiving sleeve is dust-tightly sealed against the drive spindle by sealing means. Further, advantageously, the sealing means is formed as a diaphragm seal having at least one drape. This provides for a trouble-free, sufficiently large axial displacement of the receiving sleeve.
Advantageously, the sealing means is secured with its one end to a spring cap that is itself dust-tightly secured on the receiving sleeve, e.g., by an O-ring. This permits to reduce the axial length of the chuck.
A working tool to be received in a chuck of a hand-held power tool, which has a receiving sleeve fixedly connected with the chuck for joint rotation therewith and for limited axial displacement relative thereto, and at least one locking member radially displaceably supported in the receiving sleeve, includes a shank receivable in the receiving sleeve of the chuck, and having a locking recess spaced from an end surface of the shank by a distance amounting to a tripple of a shank diameter and into which the locking member of the chuck is extendable for axially securing the shank in the chuck receiving sleeve. The locking recess can be formed, in particular, as a spherical cap recess or as a circular radial groove extending over at least a portion of the shank circumference. The locking recess permits to axially secure the driven (even percussively) working tool. The transmission of blow pulses itself does not require practically any limited axial displacement of the shank, rather the clearance of the formlocking connection between the locking member and the locking recess already provides for a sufficient displacement. This also contributes to the dust-tightness of the power tool because a creeping dust carry-over increases with the amplitude of the axial movement and vice versa.
Advantageously, the shank has at least one rotation-transmitting groove open at one end. This permits to transmit a high torque to the working tool.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.
The drawings show:
A hand-held power tool 1, which is shown in
The chuck shown in
The chuck 4 shown in
Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 056 531.5 | Nov 2007 | DE | national |
