Electricity: motive power systems – Three-or-more-positions motor controller systems
Patent
1995-11-03
1997-02-25
Ro, Bentsu
Electricity: motive power systems
Three-or-more-positions motor controller systems
200522, 200536, H02P 7638, H01H 906
Patent
active
056062346
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a handheld machine tool of and on a process of adjusting its potentiometer resistance. Handheld machine tools having a displaceable potentiometer which can be adjusted manually by an actuating member for controlling output are known commercially. As a result of unavoidable manufacturing tolerances and assembly tolerances the resistance in such handheld machine tools must be balanced after mounting the potentiometer in the housing by adjusting the potentiometer to a desired tap resistance at a determined setting of the actuating member. This balancing process is conventionally carried out by means of an additional balancing resistor. For example, an adjustable rotary potentiometer or an additional resistor which can be trimmed or burned off by laser technique can serve as a balancing resistor. However, the use of balancing resistors for balancing the resistance leads to additional effort resulting in unwanted additional costs, particularly for large-series manufacture.
The handheld machine tool according to the invention and the process according to the invention has the advantage over the prior art that additional balancing resistors are not required for balancing the resistance of the potentiometer so that the production costs for the handheld machine tool can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiment examples of the invention are shown in the drawing and explained more fully in the following description.
FIG. 1 shows a plan view of a handheld power drill as an example of a handheld machine tool outfitted with a potentiometer;
FIG. 2 shows a longitudinal section through a potentiometer according to a first embodiment example;
FIG. 3 shows a top view of a resistance path of the potentiometer;
FIG. 4 shows a partial section through an actuating member of the first embodiment example;
FIG. 5 shows a perspective view of a second embodiment example;
FIG. 6 shows a partial section through the actuating member of a third embodiment example;
FIG. 7 shows a section through a potentiometer according to a fourth embodiment example;
FIG. 8 shows a partial view of the actuating member according to FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a handheld power drill 10 as an example of an electrically powered handheld machine tool. As is known, the handheld power drill 10 has a housing 11 with an electric motor arranged therein and a tool holder 12 for receiving a drilling tool or percussive drilling tool 13, which tool holder 12 can be driven rotationally by the electric motor. The driving output of the electric motor can be controlled by a control device 14 which is constructed as a press trigger. The control device 14 has an actuating member 15 which partially projects from the housing 2. The actuating member 15 is part of a potentiometer 20 which is shown in more detail in FIG. 2.
The potentiometer 20 has an electrical resistance path 21, known per se, arranged on a resistor support 11 a which is fixed with respect to displacement relative to the housing 11. A slider 22 has pressing contact with the resistor path 21 so as to be electrically conducting. The slider 22 forms a portion of the potentiometer 20 which is displaceable relative to the housing 11 and for this purpose is connected with the actuating member 15 so as to be fixed with respect to displacement relative thereto.
As will be seen from FIG. 3, the spring end 23 of the slider 22 contacting the resistor path 21 has a fork-like design and forms two sliding fingers 22a and 22b which are electrically conducting. The resistance path 21 extends in the manner of a slide between end points 24 and 25 and has two path portions 21a and 21b which extend parallel to one another in the direction of displacement of the actuating member 15. Path portion 21 a is in electrical contact with path portion 21b of the resistance path 21 via sliding finger 22a and sliding finger 22b of the slider 22. The electrical resistance which takes effect in so doing is smaller than the correspon
REFERENCES:
patent: 4118614 (1978-10-01), Leibundgut
patent: 4649245 (1987-03-01), Lessig, III et al.
patent: 5200657 (1993-04-01), Prestel
Fernandes Angelo
Havenstein Guillermo
Kraenzler Ernst
Seel Ottmar
Ro Bentsu
Robert & Bosch GmbH
Striker Michael J.
LandOfFree
Electrically powered hand tool with potentiometer and process fo does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrically powered hand tool with potentiometer and process fo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrically powered hand tool with potentiometer and process fo will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1976327