Pumps – Condition responsive control of pump drive motor – By control of electric or magnetic drive motor
Reexamination Certificate
1999-11-22
2001-08-07
Thorpe, Timothy S. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
By control of electric or magnetic drive motor
C417S423100
Reexamination Certificate
active
06270320
ABSTRACT:
The invention relates to an electric motor, with a fan wheel, for forming an axial or radial fan. The invention also relates to an axial or radial fan with an electric motor according to the invention.
PRIOR ART
In a known electric motor, the drive unit and the control unit are thermally decoupled by being physically separate in structure; for the sake of better heat dissipation, the control unit is disposed in the fan casing and is connected to the drive unit via a cable harness. This arrangement does not have optimal fan efficiency, and because of the additional provision of the cable harness that connects the control unit to the drive unit, it cannot be manufactured optimally.
In a known hot blower with integrated electronics, the control unit is integrated in the housing of the drive unit and is protected against environmental factors, using a common cover cap, by means of a potting compound. In this hot blower, there is no need for formal decoupling between the control unit and the drive unit, and it is therefore not provided.
Another electric motor for an axial fan is known from European Patent Disclosure EP 0 715 396 A1. This known electric motor has a cylindrical motor housing, in front of a front face end a fan wheel is connected to the rotating shaft, and a rear face end is formed by a bearing plate on which a governor housing is mounted, on a side behind the motor and remote from the fan wheel. Between the motor housing and the governor housing, there is an air gap, and the electrical connection between the motor and the governor is made by means of a cable harness that spans this air gap. On the one hand, the thermal decoupling between the motor housing and the governor housing is not optimal, despite the air gap, because the governor housing is secured directly to the motor housing; on the other hand, the provision of a cable harness for electrically connecting the governor to the motor requires complicated and expensive electrical connection work in the final manufacture of a motor or the axial fan.
Such complicated assembly work increases the production cost and is therefore undesired. Furthermore, thermal influences on the part of the control unit on the drive unit should be avoided as much as possible.
ADVANTAGES OF THE INVENTION
The electric motor has an advantage over the prior art that because of the provision of the contact elements associated with one another, fast mounting of the control unit on the drive unit is possible, so that the control unit and drive unit can be prefabricated in modular form and then mounted together. When the contact elements are extended out of the respective housing, a direct housing contact between the drive unit and the control unit is not necessary, and thus improved thermal decoupling is attainable.
It is especially advantageous if the drive unit and the control unit are embodied cylindrically. In this way, both the drive unit and the control unit can be mounted in the lee of the hub of the fan wheel of an axial fan relative to the flow, so that the flow remains maximally unimpeded.
It is also possible, however, for the drive unit to be embodied cylindrically, while the control unit has a partly cylindrical, in particular semicylindrical, form. As a result, once again the flow through the axial fan is maximally unaffected. The advantage of this version, however, is that the control unit can be inserted laterally for assembly, or in other words crosswise to the axis of the electric motor, which for certain constructions and in particular certain constructions of contact elements makes for easier installation.
It is especially advantageous if the contact elements of the drive unit are provided in a region of the center axis and extend substantially axially out of the contour of the drive unit, and that the contact elements of the control unit are provided in a region of the center axis in a recess of the housing of the control unit. The phrase “in the region of the center axis” means for instance disposed around the center axis. In this embodiment, the courses for the electrical lines between the winding of the drive unit and the open- or closed-loop control electronics in the control unit are minimized in length, thus minimizing both line losses and the outputting of interference signals to the outside.
It is also advantageous if the control housing is provided with a further recess in its outside circumference, and if in the further recess, connection elements for the supply of current to the control unit are provided. By the provision of connection elements, the possibility is intrinsically created of installing the control unit in modular form and replacing it as needed, without requiring complicated electrical connection work.
Disposing the connection elements in a recess in the outer circumference assures that the electrical connections for the control unit will not protrude into the flow conduit of an axial fan, and thus will not impede the air flow.
An especially advantageous possibility for installing the control unit exists if the contact elements of the drive unit are formed by contact pins, while the contact elements of the control unit are formed by contact bushes or contact forks. In this way, the control unit can be attached to the drive unit simply and without major electrical installation work. If contact forks are used, the connection between the contact pins and the contact forks can be secured in some other way as well, such as by soldering or welding or with screws or rivets.
Alternatively, the contact elements of the drive unit can be formed by contact bushes or contact forks, while the contact elements of the control unit are formed by contact pins. Once again, this makes it possible simply to put the control unit and the drive unit together.
In an especially advantageous feature, the control housing is provided with fastening tabs protruding from the outline of the housing. These fastening tabs allow the control unit to be mounted in spaced-apart fashion on the corresponding mounting face, such as the hub of a stator, and as a result there is only slight surface contact between the control unit and the associated mounting face, so that direct heat dissipation from the control unit to the mounting face is minimized.
If electronic power components are connected to the tub-like control housing in electrically insulating and highly heat-conducting fashion, and if the control housing is formed of a material that is a good heat conductor, than good heat dissipation is assured.
If the heat-dissipating face of the tub-like control housing is located on the side remote from the drive unit, then the heat occurring in the control housing is carried away by the air flow as it sweeps passed and is not conducted to the drive unit.
If the control housing is provided with cooling fins, then the heat dissipation becomes perceptibly more effective.
The invention also relates to an axial or radial fan with an electric motor, in which the rotating part of the drive unit is connected to a fan wheel, and the non-rotating part of the drive unit is connected to a stator flange, and the stator flange is located between the drive unit and the control unit. An axial or radial fan of this kind is distinguished by a modular design, in which the drive unit and the control unit can be produced, mounted and also replaced separately. The disposition of the stator flange between the drive unit and the control unit assures an extremely effective thermal decoupling of the control unit from the drive unit, so that the direct heat conduction from the control unit to the drive unit is greatly minimized. Since the control unit is located behind the drive unit and the stator flange, or in other words on the downstream side of the air flow passing through the axial or radial fan, the heat that occurs in the control unit is dissipated directly to the air flow; to that end, cooling fins can also be provided in the control housing, in a known manner.
It is additionally advantageous if an air chamber is additionally formed between the drive unit
Heyder Martin
Schwenk Wolfgang
Gartenberg Ehud
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Thorpe Timothy S.
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