Hand-held drill with a compressed air-operated hammer mechanism

A hand drill including a housing (2), a rotary drive (8-15) arranged in the housing (2) for driving a chuck (6) provided at a front, in the drilling direction, end of the housing and in which a drill or a chisel tool is received, a compressed air-operated hammer mechanism having a pneumatic cylinder (22), a die member (15) for imparting axial blows to the drill or chisel tool, and a percussion piston (30) displaceable in the pneumatic cylinder 922) upon being impinged by compressed air for intermittently applying axial blows to the die member (15), and a reversing valve for connecting the hammer mechanism (22) with a source of compressed air, integrated in the percussion piston (30), and having a plurality of recesses and bores (46-52) alternatively operationally connectable with at least one inlet opening (23) and at least one discharge opening (24) of the pneumatic cylinder (22) for feeding the compressed air into the pneumatic cylinder (22) and for discharging the compressed air therefrom.

If you were to search for Hand-held drill with a compressed air-operated hammer mechanism using relaxed search criteria, these patents would come up:

What is claimed is:

1. A hand-held drill, comprising a housing (2); a chuck (6) provided at a front, in a drilling direction, end of the housing (2) for receiving one of a drill or chisel tool(7); a motor a rotary drive (8-15) arranged inside the housing for driving the chuck, together with the one of drill and chisel tool receivable in the chuck; a compressed air-operated hammer mechanism (21) for generating axial blows to be applied tothe one of drill and chisel tool; and a compressor driven by the motor for providing of compressed air (17) communicating with the hammer mechanism, the hammer mechanism having a pneumatic cylinder (22) with at least one inlet opening (23) and at leastone discharge opening (24), a die member (15) for imparting the axial blows, which are generated by the hammer mechanism, (21), to the one of drill and chisel tool and extending through a front limiting surface (25) of the pneumatic cylinder (22), and apercussion piston (30) displaceable in the pneumatic cylinder (22) upon being impinged by compressed air for intermittently applying axial blows to the die member (15), and a reversing valve for connecting the hammer mechanism (21) with the source ofcompressed air, integrated in the percussion piston (30), and having a plurality of recesses and bores (46-52) alternatively operationally connectable with the at least one inlet opening (23) and the at least one discharge opening (24) of the pneumaticcylinder (22) for feeding the compressed air into the pneumatic cylinder (22) and for discharging the compressed air therefrom, wherein the reversing valve has opposite ends which extend, in forward and rearward stroke positions of the percussion piston(30), beyond a rebound surface (33) and a rear surface (34) of the percussion piston (30), respectively, and engage the front limiting surface (25) and a rear limiting surface (26) of the pneumatic cylinder (22), respectively.

2. A hand-held drill as set forth in claim 1, wherein the reversing valve comprises a switch piston (41) axially displaceable between two end positions, whereby the reversing valve is switched between feeding and discharge positions thereof.

3. A hand-held drill as set forth in claim 1, wherein a compressible helical spring (40) is arranged in a rear pressure chamber (36), which is formed between the rear surface (34) of the percussion piston (30) and the rear limiting surface (26)of the pneumatic cylinder (22), for storing energy, which is generated during the rearward stroke of the percussion piston (30) and for applying additional acceleration to the percussion piston (30) during the forward stroke of the percussion piston.

4. A hand-held drill as set forth in claim 1, further comprising an adjustable plate (27) located in the pneumatic cylinder (22) and forming the rear surface (26) of the pneumatic cylinder (22), and means for changing an axial position of theadjustable plate (27) in the pneumatic cylinder (22).

5. A hand-held drill as set forth in claim 4, wherein the axial position of the adjustable plate (27) is changed continuously.

6. A hand-held drill as set forth in claim 4, wherein the axial position of the adjustable plate (27) is changed during the operation of the drill.