Method and circuit arrangement for operating an electric motor
First Claim
1. A circuit arrangement for operating an electric motor (1), comprising:
- a manually operable switch (3) for turning an operating voltage for the electric motor (1) off and on;
an electronic switch (4) for selectively applying the operating voltage to the electric motor (1);
first means for controlling the electric switch (4) so as to operate the electric motor (1) during a first operating phase at a first rotation speed until a preset limiting torque is reached, the first means includinga device (6) for measuring an actual variable, which represents the torque of the electric motor (1), anda device (8) for presetting a reference variable, which represents the limiting torque, andsecond means, connected to the first means, for causing the first means to control the electric switch (4) so as to operate the electric motor (1) in a second operating phase after the limiting torque has been reached and until the electric motor (1) is turned off with the manually operable switch (3), the electric motor (1) exerting intervals of a final torque (20) separated by torque pauses (19) during the second operating phase.
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Accused Products
Abstract
The invention relates to a method for operating an electric motor in an electrical hand-held tool, such as an electric screwdriver, battery-powered drill or the like, the electric motor being operated during the operating phase (17) at a first rotation speed, which can possibly be preset variably, until a preset limiting torque is reached. On reaching the limiting torque, the electric motor is switched to a further operating phase, which lasts until the electric motor is switched off manually by the user. In this further operating phase, a final torque (20), which is interrupted periodically by torque pauses (19), is exerted by the electric motor. A circuit arrangement for implementation of this method is also described.
73 Citations
19 Claims
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1. A circuit arrangement for operating an electric motor (1), comprising:
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a manually operable switch (3) for turning an operating voltage for the electric motor (1) off and on; an electronic switch (4) for selectively applying the operating voltage to the electric motor (1); first means for controlling the electric switch (4) so as to operate the electric motor (1) during a first operating phase at a first rotation speed until a preset limiting torque is reached, the first means including a device (6) for measuring an actual variable, which represents the torque of the electric motor (1), and a device (8) for presetting a reference variable, which represents the limiting torque, and second means, connected to the first means, for causing the first means to control the electric switch (4) so as to operate the electric motor (1) in a second operating phase after the limiting torque has been reached and until the electric motor (1) is turned off with the manually operable switch (3), the electric motor (1) exerting intervals of a final torque (20) separated by torque pauses (19) during the second operating phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 13)
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10. A method for operating an electric motor (1) which can be turned on and off manually, comprising the steps of:
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(a) after the electric motor (1) is turned on, driving the electric motor (1) during a first operating phase (17) at a first rotation speed until a preset limiting torque is reached; and (b) when the limiting torque is reached, switching the electric motor (1) to a second operating phase which lasts until the electric motor (1) is turned off, the electric motor (1) exerting a final torque (20) which is interrupted periodically by torque pauses (19) during the second operating phase. - View Dependent Claims (11, 12, 14, 15, 16, 17, 18, 19)
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Specification