Electricity: circuit makers and breakers – Electric switch details – Actuators
Reexamination Certificate
2001-07-11
2002-12-03
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Electric switch details
Actuators
C200S00100B
Reexamination Certificate
active
06489578
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an electrical switch for use in electric hand tools, such as electric drills, hammer drills, electric screwdrivers or the like, to switch the electric motor on and off and, if appropriate, to control the rotational speed of the electric motor.
DE-A 24 10 871 discloses an electrical switch with a housing in which a contact system is arranged. Mounted such that it can be moved on the housing is an actuating member which serves as a manual handle and which can be moved by the user into an actuating or operating position. In the operating position, the actuating member then acts to switch the contact system. In order to lock the actuating member in the operating position, the switch also has a locking device. The locking device comprises a slide that is connected to the actuating member and is guided on a side wall of the housing, and an actuating element that is mounted such that it can be moved on the side wall of the housing. By means of manual movement of the actuating element essentially perpendicularly with respect to the side wall of the housing, in the operating position of the actuating member, the actuating element can be brought to interact with the actuating member in order to lock the actuating member.
The actuating element for the known locking device is located on the side wall of the housing of the switch. In many cases, when the electric hand tool is used, manual handling of the actuating element can become arduous.
A switch for an electric tool, having a lateral locking device actuated by a plunger is also disclosed by U.S. Pat. No. 3,814,886. In addition, the switch has a changeover switch for reversing the direction of rotation of the electric tool. A rotary knob for actuating the changeover switch is arranged concentrically with a sleeve to accommodate the plunger. The rotation of the rotary knob about the sleeve moves a contact slide, which is connected to the rotary knob by means of a joint, as a result of which the changeover switch is actuated in order to reverse the polarity of the electric motor. The plunger for the locking device and the rotary knob for the changeover switch for reversing the direction of rotation are two separate actuating elements which differ from each other. Because of the lateral arrangement of the two actuating elements, again their manual operability can be made more difficult.
Furthermore, U.S. Pat. No. 4,097,703 discloses an electrical switch for electrical appliances in which an actuating member can be moved from an initial position into an operating position, so that, in the operating position, the actuating member acts to switch a contact system and to adjust a potentiometer. The switch has a movable actuating element which, during its movement, acts to actuate a first locking device on the switch. For electrical appliances with an electric motor which can be operated reversibly and which can be operated in two opposite directions of rotation, this switch has an additional switching element for changing over the direction of rotation. This additional switching element is actuated by a slide which is located on the rear of the switch, which is opposite the actuating member and the actuating element. Here, too, the actuation of actuating member, actuating element and slide is made more difficult for the user during the use of the electrical appliance. In particular, there is a risk of maloperation.
As a rule, so-called universal motors are used in electrical appliances. In these universal motors, the carbon brushes which feed the power to the armature via the collector are adjusted from the neutral position by a certain angle in order to achieve optimization of the motor operation in one direction of rotation. In order to achieve optimization in the other direction of rotation of the electric motor as well, a device for adjusting the carbon brushes can also be arranged on the electric motor.
DE 195 45 651 A1 discloses a device for adjusting the carbon brushes for the electric motor in accordance with its direction of rotation. This device for adjusting the carbon brushes has a pivotable carrier, on which brush holders for the carbon brushes which slip on the collector of the electric motor are arranged. The carrier can be pivoted manually by means of an actuating element. The electrical changeover switch for the direction of rotation of the electric motor can be integrated into this device for adjusting the carbon brushes at the same time.
In order to start up the electrical appliance, the user has to set the direction of rotation by means of the actuating element located on the device for adjusting the carbon brushes. In addition, in order to operate the electrical appliance, the actuating member of the electrical switch has to be actuated manually by the user. Both the electrical switch and the device for adjusting the carbon brushes are arranged at different points relatively far removed from each other on the electrical appliance, which means that when the electrical appliance is being used, manual handling of the actuating element can be made more difficult.
Finally, EP-A2-0 057 414 discloses an electric hand tool having a switch which has a trigger, a changeover switch for the direction of rotation of the electric hand tool additionally being arranged on the switch. The changeover switch can be actuated by means of a sliding handle, which is fixed to a lever which is arranged on the upper side of the trigger and can be pivoted about an axis. In addition, a brush carrier with brush holders for the electric motor is arranged in the housing of the electric hand tool such that it can be adjusted. When the lever for actuating the changeover switch is pivoted, at the same time the brush carrier is adjusted. To this end, there is a fork element on the lever, which interacts with a stub axle on the brush holder of the brush carrier.
In this known electric hand tool, two devices are actuated simultaneously by means of the lever as an actuating element, namely on the one hand the adjusting device for the brush carrier and on the other hand the changeover switch for the direction of rotation of the electric motor. However, the lever does not permit mutually independent actuation of the two devices, so that the manual handling of the actuating element is severely restricted.
Starting from EP-A2-0 057 414, the invention is based on the object of developing the electrical switch for an electrical appliance further in such a way that the operation becomes more simple and more convenient for the user.
In a generic electrical appliance, this object is achieved by an electrical switch and a movable actuating element. The electrical switch has an actuating member that can be moved between an initial position and an operating position in a direction of movement. The actuating member, in the operating position, acts to switch a contact system or to adjust a potentiometer. The movable actuating element is arranged in an immediate vicinity of the actuating member. The actuating element, during movement, acts to actuate a first device and a second device. The actuating element includes a first part being mounted such that it can be moved in a second direction and a second part that can be moved both with the first part in the second direction and also in a first direction that is different from the second direction such that the first device is actuated when the actuating element is moved in the first direction, and the second device is actuated when the actuating element is moved in the second direction.
One of these two directions may lie within an angular range of less than +/−90 degrees in relation to the direction of movement of the actuating member. The angle in relation to the direction of movement of the actuating member is preferably up to a maximum of +/−15 degrees. In particular, the actuating element can be moved approximately in the direction of the actuating member.
For the purpose of particularly good handling, the actuating element adjusting the carbon b
Jung Peter
Merkel Klaus
Niklewski Gerhard
Friedhofer Michael
Marquardt GmbH
Morgan & Lewis & Bockius, LLP
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