Method for controlling a screwdriver and screwdriver
First Claim
1. A method for controlling a screwdriver having an electric motor, the electric motor having a distinct ratio of rotational speed to torque at a given effective voltage, the method comprising:
- predefining a constant effective voltage for the operation of the electric motor, said predefined effective voltage associated with an unloaded rotational speed;
predefining a cutoff rotational speed which corresponds to a predetermined cutoff torque at the predefined effective voltage, the cutoff rotational speed being a minimum speed threshold below which the cutoff torque is exceeded;
operating the screwdriver under load, wherein operating the screwdriver under load comprises maintaining the predefined effective voltage without controlling the rotational speed of the motor by dynamically adjusting the current;
during operation of the screwdriver under load, determining a detected rotational speed of the electric motor when the electric motor is operating at the predefined effective voltage, said detected rotational speed being less than the unloaded rotational speed; and
when the detected rotational speed at the predefined effective voltage is decreased to the cutoff rotational speed by the load, switching off the electric motor.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for controlling a screwdriver that has an electromotor, the electromotor having a clear ratio of rotational speed (n) to torque (M) at a defined effective voltage (Ueff soll), involving the following method step: —defining an effective voltage (Ueff soll) for operating the electromotor, —defining a cut-off rotational speed (nab) that corresponds to a pre-defined cut-off torque (Msoll) at the pre-defined effective voltage (Ueff soll), —operating the screwdriver under load with the pre-defined effective voltage (Ueff soll), —during operation of the screwdriver: —determining the rotational speed (n), —shutting down the electromotor when the cut-off rotational speed (nab) is attained.
-
Citations
12 Claims
-
1. A method for controlling a screwdriver having an electric motor, the electric motor having a distinct ratio of rotational speed to torque at a given effective voltage, the method comprising:
-
predefining a constant effective voltage for the operation of the electric motor, said predefined effective voltage associated with an unloaded rotational speed; predefining a cutoff rotational speed which corresponds to a predetermined cutoff torque at the predefined effective voltage, the cutoff rotational speed being a minimum speed threshold below which the cutoff torque is exceeded; operating the screwdriver under load, wherein operating the screwdriver under load comprises maintaining the predefined effective voltage without controlling the rotational speed of the motor by dynamically adjusting the current; during operation of the screwdriver under load, determining a detected rotational speed of the electric motor when the electric motor is operating at the predefined effective voltage, said detected rotational speed being less than the unloaded rotational speed; and when the detected rotational speed at the predefined effective voltage is decreased to the cutoff rotational speed by the load, switching off the electric motor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A screwdriver, comprising:
-
an output portion and a drive portion having an electric motor, the electric motor having a distinct ratio of rotational speed to torque at a given effective voltage, and the drive portion having a control means for controlling the electric motor, an effective voltage driving the electric motor being adjustable by means of the control means, said effective voltage being associated with an unloaded rotational speed, wherein a rotational speed detecting device detects the rotational speed of the electromotor during operation of the screwdriver under load, wherein operation of the electric motor under load comprises operation of the electric motor at the effective voltage without control of the rotational speed of the motor based on dynamic adjustment of the current, said detected rotational speed being less than the unloaded rotational speed, wherein a cutoff rotational speed, which at a predefined constant effective voltage corresponds to a predetermined cutoff torque, the cutoff rotational speed being a minimum speed threshold below which the cutoff torque is exceeded, is set by means of the control means, and wherein the rotational speed detecting device transmits the detected rotational speed to the control means, with the control means switching off the electric motor when the detected rotational speed at the effective voltage is decreased to the cutoff rotational speed by the load. - View Dependent Claims (9, 10, 11, 12)
-
Specification