Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1996-08-15
1998-03-24
LaBalle, Clayton E.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 90, 310 43, H02K 504, H02K 516
Patent
active
057316465
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electric motor, in particular an electric motor for wiper systems.
BACKGROUND OF THE INVENTION
With respect to motors of this type which are mass produced, it is particularly important that they have a long useful life and be inexpensive to manufacture. The selection of the materials to be used should take into account the demands made on the capacity of the motor and the properties of the materials. For example, plastic materials permit the injection-moulding of relatively complicated shapes. However, plastic materials have a poor heat conductivity. Metal, in turn, has good heat conductivity with a low magnetic resistance but yields to corrosion. Further, the combination of plastics and metal involves difficulties due to their different expansion characteristics. Also, elements made of different materials must be connected with sufficient strength to permit operation over the projected life of the motor while permitting separation for recycling when the motor is finally removed from operation.
A large number of motor housings are known in the art wherein the individual motor elements are made of plastics and metal. For example, German patent application, No. 30 38 135, discloses a housing of a small-size electric motor having a cylindrical metal casing to which a plastic bearing plate is mounted. In addition, the motor plate has a heat dissipation element made of metal which makes catch at the motor beating. In this arrangement, the heat dissipation element can abut the metal casing of the housing, the heat dissipation effect being increased still further.
An object of the present invention is to provide an inexpensive, high-resistance long-service electric motor, in particular an electric motor for windshield wiper systems, by appropriately selecting the metal and plastic materials used therein. In addition, the motor shall have an improved ability to dissipate heat caused by operation of the motor.
In principle, the present invention has for its purpose to integrally connect the metal casing to the heat dissipation element and to injection-mould the motor plate including bearing to the so formed structure. A special benefit provided by this arrangement is that the heat produced in the motor bearing can be dissipated satisfactorily to the large-surface metal casing due to the material transition between the metal casing and the heat dissipation.
A special rigidity between the bearing plate and the metal casing is achieved by injection-moulding or casting the bearing plate. In addition, the injection-moulding or casting operation provides a high degree of seal-tightness of the housing interior with relation to the surrounding atmosphere. When shaping the plastic bearing plate it will be ensured that the plastic material back grips metal elements for reasons of strength. It is not desirable that the heat dissipation element is fully enclosed by plastics, so that the heat dissipation is not impaired. Therefore, it is preferred that the heat dissipation elements remain virtually free from plastic injection-coating. However, this means that the corrosion strength of the metal is an important aspect. Preferably, the plastic material is applied at least to those metal points which have an imminent risk of corrosion due to the manufacturing method.
It is possible to provide the plastic bearing element, in which finally the armature shaft of the motor extends, directly in the plastic moulding process, depending on the tensile load. In a number of applications, however, the load on the bearing can be so high that the capacities of the plastic material used for the bearing plate cannot stand the load (for example, when subjected to heat). In a preferred aspect of the present invention a sintered metal bearing is inserted into the motor housing prior to the plastic injection moulding operation. The sintered metal bearing is then injection-coated by the plastic material for providing the plastic bearing element. The advantages of such sintered metal bearings are
REFERENCES:
patent: 3824684 (1974-07-01), Wheeler
patent: 4309815 (1982-01-01), Schmitt et al.
patent: 4623810 (1986-11-01), Smith
patent: 4823032 (1989-04-01), Ward et al.
patent: 4862582 (1989-09-01), Henck
patent: 5138208 (1992-08-01), Kondo et al.
patent: 5201111 (1993-04-01), Prohaska
patent: 5268607 (1993-12-01), McManus
Search of the German Patent Office for Application P4321027.9.
English Translation of the International Preliminary Examination Report for Application PCT/EP94/02019.
Baumeister Udo
Buhler Roland
Czermak Martin
Heinze Mark
Walther Bernd
ITT Automotive Europe GmbH
LaBalle Clayton E.
LandOfFree
Heat-protected motor housing with metal casing and plastic plate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat-protected motor housing with metal casing and plastic plate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat-protected motor housing with metal casing and plastic plate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2291283