Catch mechanism for a dental handpiece

#The present invention is directed to a catch mechanism for releasably connecting a head part to a gripping part of a dental handpiece. The head part contains a head housing with a neck part terminating in a shank which is received in a guide sleeve of the gripping part and the shank and guide sleeve are provided with anti-twist elements to prevent rotation therebetween. The catch mechanism will include at least one catch element have a radially acting engageable element which is carried by one of the two parts and cooperates with a stop face on the other of the two parts to form a latching connection between the two parts while assembled and the mechanism includes an actuation element for disengaging the catch element from the stop face to enable disassembly.

#A radially actuated catch mechanism is disclosed in U.S. Pat. No. 4,348,180 whose disclosure is incorporated by reference thereto and which patent claimed priority from a European application which issued as European Pat. No. 0,029,862. As disclosed in this patent, the neck part of the head part contains a spring-elastic annular sleeve which forms a surface of the handpiece in this region and terminates flush with the surface of the neighboring handpiece parts. Located in a lateral surface region, which is tangential with the head housing, are webs or ridge members which extend parallel to the axis of the annular sleeve and on whose free ends are outwardly directed catch noses or elements which are designed to move radially inwardly and outwardly to engage corresponding recesses in a gripping sleeve. The latch connection can be released in that the head part is grasped with the thumb and index finger in the region of the side edges of the neck part, for example, preferably in the region which is practically tangential with the head housing and are pressed against the annular sleeve. As a result of a deformation of the annular sleeve produced in this way, the catch noses will be disengaged from the locking recesses in the grip part.

#In terms of surface, this arrangement of the elastic annular sleeve as well as the webs connected thereto to extend parallel to the axis and having the catch noses, takes a comparably great amount of space. Added thereto is that the sleeve acting as an actuation member forms a relatively large visual surface which must be executed in accordance with the remaining handpiece surface and is, thus, relatively cost intensive.

#FIG. 1 is a perspective view of a dental handpiece in accordance with the present invention;

#FIG. 2 is a perspective view of a first embodiment of a head part in accordance with the present invention;

#FIG. 3 is an enlarged perspective view of an end of a gripping part of the hand piece of the present invention;

#The principles of the present invention are particularly useful when incorporated in a dental handpiece 1 of FIG. 1. The handpiece 1 is connected to a supply hose 3 by means of a rotatable connection 2. The handpiece 1 has a hand piece portion 4 which faces the rotatable connection 2 and contains a drive unit (not shown in detail), for example an electric motor or an air motor. A gripping part 5 extends from the handpiece portion 4 and terminates in a head part 6. In a known way, the head part 6 contains a head housing 7 which has a rotatable socket for receiving a tool, such as a burr 107, and has a relatively short neck part 8. In FIG. 1, an actuation element 9 for a catch means for axially latching of the head part 6 relative to the gripping part 5 is illustrated. The catch means will be discussed in greater detail in the following.

#The head part 6, as illustrated in FIG. 2, comprises an essentially cylindrical shank 10 in which a drive shaft 11 for driving a tool is rotatably received. A catch nose 12, which comprises a stop face 12a, is located on an upper surface of the shank 10. An anti-twist element in the form of a projection or spline 13 extends parallel to the axis of the shank 7 on an under surface thereof. A relatively short neck part 8 has projections 14 which extend in an axially direction on both sides of the shank so that when the head part is inserted onto the gripping part or gripping piece 5, the projections 14 will provide further anti-twist protection relative to the gripping part, particularly when the catch mechanism has been set.

#As best illustrated in FIG. 3, the gripping part or piece 5 has an outer sleeve 15 and a guide sleeve 16 is secured in the sleeve 15 and has an axial bore 108 for accepting the shank 10 of the head part 6. As illustrated, the sleeve 15 provides a space for receiving the actuating element 9.