Small-size motor and a process for manufacture and use thereof

Small-size motors, particularly vehicle step motors in a system used to adjust vehicle parts, are connected directly with a housing in which an assigned electronic control system is housed. A bus supplies each of the motors or its associated electronic control system with adjusting commands and energy. The housings in which the electronic control systems are housed, are closed off tightly with respect to dust and dirt but not with respect to vapor, so that moisture can diffuse out of these housings. This arrangement permits a simple and operationally reliable construction.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to small-size motors and, more particularly 
to stepping and servo motors that may be used in a motor vehicle to adjust 
various vehicle parts, and to methods of manufacturing and using the same. 
Small-size motors, particularly step motors and servomotors, are being used 
increasingly, in some cases in considerable numbers, for the adjustment or 
setting of system elements such as are found in motor vehicles. This use 
partially takes place under extreme conditions, for example, in automobile 
construction, where the motors must operate reliably under considerable 
temperature fluctuations in a dusty, dirty, damp and even wet environment. 
Usually, such small-size motors, particularly step motors, are controlled 
by a central electronic control system which generally requires an at 
least four-conductor cable connection from the central electronic system 
to each motor and is therefore connected with considerable expenditures. 
In addition, a considerable number of connecting points are required, and 
these points are frequently the cause of interruptions and, therefore, of 
operational failures. 
It is an object of the present invention, therefore, to simplify control 
and cabling and, therefore, to make the motor operationally more reliable. 
It is a further object of the invention to configure the motor such that it 
operates reliably in a continuous manner also under extreme operating 
conditions, for example, in the engine compartment of a motor vehicle. 
According to a presently contemplated embodiment of the present invention, 
these objects have been achieved by arranging an electronic control system 
directly with the motor. As a result, a secure and direct connection is 
achieved between the electronic system and the motor without any cabling, 
and the cabling can be simplified in that the individual motors are 
controlled by a central electronic control system by way of a databus and 
may be supplied with energy by way of parallel or joint conductors. 
Instead of a large number of cables which are laid in a star shape from 
the electronic control system to the individual motors, a single cable, 
which in general has no more than three leads, can be guided along the 
shortest path from the central electronic control system to all motors. 
The electronic control system is preferably housed in a plastic housing 
which is firmly connected with the coil form of the motor. This housing is 
preferably provided with an end element which is not sealed hermetically 
and which, although it prevents dust and dirt from entering into the 
housing compartment, permits a sufficient vapor exchange in order to 
permit condensed water formed in the housing to evaporate and discharge.

DETAILED DESCRIPTION OF THE DRAWINGS 
In the small-size step motor 1, shown in FIG. 1, the coil form 2, which is 
made of plastic, is provided with one or several connecting extensions 
which reach through the stator parts of the motor and with which a plastic 
housing 3 is firmly connected by, for example, gluing or fusing. This 
plastic housing 3 is used for receiving an electronic control system for 
the motor 1, and it is equipped with a connection bush 4 for a cable plug. 
It is indicated by dash-dotted lines that housing parts may be provided 
which are equipped with connection bushes 4' at different points in order 
to be able to select the most favorable position of this connection bush 
for all applications. 
FIG. 2 is a longitudinal sectional view of one embodiment of the housing 3 
with the electronic control system shown schematically in FIG. 1. The 
housing 3 comprises a housing top part 3a and a housing bottom part 3b 
which is, for example, fused thereto. In the housing bottom part 3b, a 
connection body 5 is disposed therein, and contacts are situated to form a 
plug-type connection with connection pins 6 of the motor coil form (not 
shown in FIG. 2). These connection pins 6 penetrate conical guiding bushes 
7 of a guiding part 8. 
A printed circuit board 9 is held between the two housing parts 3a, 3b, to 
which an integrated circuit 10 and a switching element, or possibly a 
cooling element 11, of the electronic control system is connected. 
Connection pins 12 project into the connection bush 4 and are soldered to 
the printed circuit board 9. Multiple contact pins 12, e.g. three, may be 
provided, although only one is shown in FIG. 2. A lateral housing opening 
13 is closed off by the flat leg 14a of an L-shaped leaf spring 14. The 
end of the leaf spring 14 rests elastically on the printed circuit board. 
The leaf spring 14 is divided in a comb-like manner into several teeth 
14b, in which case these teeth are dimensioned and arranged such that they 
reach between strip conductors of the printed circuit board 9. 
The leaf spring 14 forms a not-completely hermetic or steam-tight closing 
of the housing 3, but is sufficient, however, for preventing dust, dirt or 
liquid from entering the housing while permitting but permits a certain 
vapor or steam exchange between the interior of the housing and the 
environment in order to permit condensation water or ice, which may have 
formed inside the housing 3, to evaporate and be discharged. In addition, 
the leaf spring 14 has the purpose of efficiently discharging heat from 
the printed circuit board 9 which may originate mainly from the motor 
drivers. 
FIG. 3 illustrates another embodiment of the present invention in which the 
corresponding parts have the same reference numbers as in FIG. 2 and 
therefore do not need to be described again. The closing element for the 
opening of the housing 3 is again constructed as a leaf spring 15 which, 
however, rests by way of spring ends against the top side and the bottom 
side of the printed circuit board 9 and thus ensures a still more 
intensive cooling of the electronic system. 
FIG. 4 illustrates still another embodiment of the present invention 
according to which the opening of the housing 3 is closed by a plastic lid 
16 with which a leaf spring 16a is connected which is similar to that of 
FIG. 3 in that the ends of the spring 16a rest against the top and bottom 
side of the printed circuit board 9. This leaf spring is thus used both as 
a holding element for the lid 16 and for the cooling of the printed 
circuit board 9. 
FIG. 5 illustrates a further embodiment of the present invention similar to 
that in FIG. 4 with a plastic closing element 17 but which is provided 
with a differently shaped leaf spring 18 as the holding and cooling 
element. 
FIG. 6 illustrates yet another embodiment of the present invention with a 
plastic closing element 19 which is not connected with a holding spring 
but is glued or welded at spaced points to the housing 3. The leaf spring 
20, has a W-shaped part 20b which rests on the printed circuit board 9 at 
two spaced points and therefore acts as a cooling element, and a leg 20 
which is pushed into a deep groove of the housing top part 3b. 
FIG. 7 illustrates four small-size motors 1 which are controlled and fed by 
a common central electronic control system 21. The electronic control 
system is connected in parallel with a three-conductor bus cable. Two 
conductors 22, 23 of this cable are used for the energy supply of the 
motors with their electronic control system, while conductor 24 is used 
for signal transmission. 
One of the conductors 22, 23 may be used for the return of the control 
signals. Only two conductors or, in an extreme case, only one conductor 
may be needed, specifically when the return or ground takes place by way 
of the mass, which is customary, for example, in vehicle construction. 
Control signals may then be transmitted and energy may be supplied by way 
of a single conductor. In the case of a single conductor, the electronic 
system of each motor has memory in which digitalized commands for the 
motor control can be stored. In addition, the electronic system of each 
motor has an individual address code, and the memories are activated when 
the corresponding address code is transmitted by the electronic control 
system 21. In this manner, each motor or the electronic system assigned to 
it can be activated individually in order to read command data into the 
memories and to control the assigned motor corresponding to these data. 
Instead of the described measures for the cooling of the electronic system 
or in addition to it, a plastic part or the housing may be connected to be 
in close contact with the printed circuit board. The connection bush 4 and 
the connection pins 12 may also be used for additional cooling. Also, a 
heat-conducting rubber may be clamped between the printed circuit board 
and the housing. However, in all instances, care must be taken that the 
heat exchange and moisture discharge are ensured. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.