Robert Boschgmbh

Karl Roll

Alfred Hettich

Klaus-Peter Fritschi

Kurt Paule

Reinhold Stroezel

Wilhelm W Schwarze

Max Burklin

Herbert Dieterle

Hubert Stahl

Wolfgang Raidt

Werner Keil

A transducer arrangement for torque and/or angular displacement measurement, especially in power screwdrivers, operates in accordance with the eddy current principle. The transducer arrangement is constructed as a self-contained structural unit having its own transducer casing which is connected by appropriate coupling and connecting parts to the housing of the power screwdriver and to the driving and driven members of the screwdriver. A torsionally deformable member, especially shaft, is interposed between the driving and driven members, being connected thereto for joint rotation therewith. When torque is applied to the deformable member, its end portions are angularly displaced relative to one another. Two slotted members, especially sleeves, are respectively connected to the end portions of the deformable member for joint angular displacement therewith, and they influence the magnetic field in the vicinity of the deformable member in proportion to their relative angular displacement. The changes in the magnetic field are detected by an electric coil arrangement whose impedance changes accordingly, and the thus obtained signal is evaluated to obtain the magnitude of the applied torque. A cable connected to the coil arrangement and extending to the exterior of the casing through an opening provided in the latter is accommodated in a tube. The tube extends along a handgrip portion of the housing of the screwdriver to protect the hand of the user.

Transducer for torque and/or angular displacement measurement,

A screwdriver comprises a planetary gear carrier rotatably carrying a plurality of circumferentially displaced planet gears meshing with a pinion driven by the motor of the screwdriver and with teeth provided on the inner surface of a coupling element in form of a hollow cylinder surrounding the carrier. The coupling element is also provided at one end with coupling teeth axially displaced from the first-mentioned teeth. The coupling element is movable by a fluid-operated piston from a first position to which it is biased by springs, in which the coupling teeth thereon are in mesh with corresponding coupling teeth on the carrier to rotate with the same speed as the latter, to a second position in which the coupling teeth on the coupling element are in mesh with stationary teeth on a housing surrounding the carrier and the coupling element to hold the latter against rotation.

Motor-driven screwdriver

A power tool includes a motor and a motor switch movable between on and off settings. A transmission connects the motor to the tool holder of the power tool. The transmission includes a torque-responsive clutch arrangement which transmits torque below a preselected value in a first manner and torque above the preselected value in a different and distinguishable second manner. The torque-responsive clutch means undergoes an automatic change of torque transmission manner in response to a rise of transmitted torque past the preselected value. A turn-off arrangement mechanically detects the automatic change of the manner in which the clutch arrangement transmits torque and in response thereto automatically moves the motor switch from the on to the off setting. An override device is activatable by the user of the power tool for mechanically preventing the automatic turn-off arrangement from turning off the motor.

Power tool

A pneumatic hand tool comprises a housing having a compressed-gas inlet and provided with a pneumatically powered motor which carries on one side a tool holder such as a chuck and on the other side a governor. A speed-control valve is operated by the governor and can close a first air passage between the inlet and the motor to maintain the motor speed below a predetermined limit. Another passage is provided which bypasses the governor-controlled speed-control valve and a valve is provided in this bypass conduit which is openable in order to allow the hand tool to operate at a speed substantially above the governor-established speed.

Pneumatically powered hand tool with speed-control governor

The power tool has a drive motor and a turn-on switch device activatable for turning on the drive motor. A manual activator is mounted for swinging movement in a predetermined plane of motion and in a predetermined direction from a normal position to an activating position in which it activates the turn-on switch device. The manual activator is so arranged and configurated as to be depressible in the predetermined direction by a hand of the user of the power tool. A safety device prevents unintentional activator depression and includes a blocking structure. The blocking structure is mounted for swinging movement relative to the manual activator in generally the predetermined plane and in the predetermined direction from a blocking position in which it prevents activator depression to an unblocking position in which it permits such depression. The blocking structure is comprised of one or more cooperating levers and is so configurated and located relative to the manual activator as to be depressible by a finger of the same hand which depresses the manual activator.

Power tool with device for preventing unintentional turn-on of drive

A clutch connects the drive motor to the rotatable tool holder. The driven part of the clutch has a plurality of clutch recesses bounded by sloping clutch ridges, with clutch balls received in the recesses. An annular pressure body surrounds the driving part and is pressed by a threshold-torque-determining spring against the clutch balls to hold them in their recesses. When the clutch torque exceeds the threshold value, the clutch balls rise out of the clutch recesses and slip over the respective clutch ridges into the respective adjoining clutch recesses. In so doing, they briefly push back the annular pressure body. This causes the annular pressure body to drive locking balls radially inward through registering radial openings in the driving part and in a locking bolt interior to the latter. When the inner locking ball moves completely into the locking bolt, locking between the driving part and locking bolt terminates. Then, a locking spring which previously participated in the locking action by urging the locking balls radially outward can shift the locking bolt axially relative to the driving part in a sence causing a release valve device to close and terminate energization of the power tool drive motor.

Growing community of inventors

Leinfelden, Germany

Karl Roll