Andreas Stihl Ag Co. Kg

Sebastian Hanussek

Tobias Deigendesch

Jan Rieger

Felix Mayer

Michael Schneider

Georg Maier

Tim Gegg

Patrick Levien

Jörg Elfner

Alexander Klein

Lukas Zuercher

A handheld work apparatus includes a work tool, a belt drive, a drive motor configured to drive the work tool via the belt drive, a brake unit configured to act on the belt drive, and a holding arrangement. The brake unit has a braking position and a released position and the holding arrangement is configured to hold the brake unit in the released position. The holding arrangement includes an electromagnet to which current is supplied during operation of the work apparatus.

Handheld work apparatus

A work apparatus has a drive motor and a work tool driven in a rotating manner by the drive motor. The work tool is at least partially covered by a protective hood which is mounted pivotably about the rotational axis of the work tool. A control unit is provided for controlling at least one component of the work apparatus. The work apparatus has a detection unit for detecting at least one position of the protective hood. The control unit is configured for controlling the at least one component of the work apparatus depending on the detected position of the protective hood. In a method for operating a work apparatus, the detection unit detects at least one position of the protective hood and supplies the information to the control unit. The control unit activates the at least one component depending on the detected position of the protective hood.

Work apparatus and method for operating the same

A work apparatus has a work tool driven by a combustion engine. A brake assembly has a brake element for braking the work tool as it slows down. In a braking position of the brake assembly, the work tool is braked, while, in a stand-by position of the brake assembly, the brake element enables the movement of the work tool. The brake element is held in the stand-by position by a holding force from an electromagnet supplied with energy by an electric generator driven by the engine, for which purpose, in the stand-by position of the brake assembly, a holding current is supplied to the electromagnet. To extend the holding time as the engine slows down, an operating parameter of the engine is monitored and, after a limit value of the operating parameter is reached, the holding current supplied to the electromagnet is reduced.

Work apparatus having an electromagnetic brake assembly

A method is for activating an electromagnetic valve including a valve seat and a valve body. The valve body is movable between a first and the second position (A, B) via an electric drive coil. The drive coil is connected to a control device which as a function of a setting variable (S) energizes the drive coil with a signal sequence consisting of control signals in order to move the valve body. The control device as a function of the setting variable (S) sets a predetermined signal amplitude and/or a predetermined signal duration of the control signals. It is provided that at least one control signal of the signal sequence is formed with an amplitude superelevated above the predetermined signal amplitude and/or with a signal duration extended beyond the predetermined signal duration.

Method for activating an electromagnetic valve

A handheld work apparatus has a tool and a brake assembly for the tool. The brake assembly has an actuating element which acts on a brake element of the brake assembly. The actuating element is movable between a fixed position wherein the tool is not braked, and a released position, wherein the brake element brakes the tool. To fix the actuating element in the fixed position, an electromagnet is provided. The electromagnet interacts with an anchor on the actuating element. The anchor is mounted via a pivot joint on an anchor pin to be pivotable about a pivot axis. A guide includes a guide part connected to the anchor and a guide part connected to the yoke, wherein, in the fixed position of the actuating element, the guide parts guide the anchor relative to the yoke in a transverse direction of an outrigger of the apparatus.

Handheld work apparatus having a work tool and a brake assembly for the work tool

A handheld work apparatus has a drive motor which drives a work tool rotationally via a belt drive. The belt drive has a first, driving pulley and a second, driven pulley. The second pulley is connected fixedly to the work tool so as to rotate therewith. The rotational speed of the second pulley is lower during operation than that of the first pulley. A brake unit acts on the belt drive. A first drive belt of a first stage and a second drive belt of a second stage act between the pulleys to transfer the drive torque. The belts each bring about a rotational speed reduction. The belt drive includes a redirection roll which bears against the belt, via which the highest drive torque is transmitted during operation. As a result, a braking operation of the work tool is enabled independently of the rotational speed of the tool.

A handheld work apparatus has a drive motor which drives a work tool in rotation via a belt drive. The belt drive has at least one first, driving pulley and at least one second, driven pulley. Between the first pulley and the second pulley there acts at least one drive belt for transmitting the drive torque. A second pulley is connected to the tool for conjoint rotation. The rotational speed of the second pulley is less than the rotational speed of the first pulley during operation. The work apparatus has a brake unit which acts on the first pulley. The belt drive includes at least one redirection roll. During braking, at least one redirection roll bears on the tight side of each drive belt which acts between the first pulley and the second pulley. This allows a simple structure and safe braking of the work tool.

A centrifugal clutch, especially in a hand held work apparatus, such as a cut-off machine (), a brush cutter or the like, having a rotational axis (), at least one movably mounted centrifugal weight () arranged at the drive end and a clutch drum () arranged at the output end. The centrifugal clutch () includes a brake device () which is released by the centrifugal weight () when the centrifugal weight () moves radially outward in relation to the rotational axis ().

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Remseck, Germany

Sebastian Hanussek