Pumps – Motor driven – Including means utilizing pump fluid for augmenting cooling,...
Reexamination Certificate
2002-05-06
2004-01-27
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Including means utilizing pump fluid for augmenting cooling,...
C417S423800, C310S062000
Reexamination Certificate
active
06682320
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an electric fan, in particular, for motor vehicles, comprising an electric drive motor, a fan wheel coupled with the drive motor, and an electronic control unit for controlling the drive motor.
Such electric fans are used, in particular, for cooling the drive units of a motor vehicle. Herein, a flow of air oriented substantially parallel to the axis of rotation of the fan wheel is generated by the fan wheel and directed, for example, at a radiator unit of the motor vehicle.
In order to achieve optimum cooling with as little energy as possible, the rotational speed of the fan wheel can be set in accordance with the respective cooling requirement. A control unit is normally used for this purpose. This is coupled with the drive motor and enables power-controlled operation of the drive motor. To this end, the control unit usually comprises a control circuit which generates a PWM signal, i.e., a pulse-width-modulated signal for controlling a power output stage, usually in the form of at least one FET output stage switch.
The control unit is usually connected via connection cables to the drive motor and arranged in a separate housing.
The object of the present invention is to make an electric fan of the kind mentioned at the outset structurally more simple and more cost-effective to assemble.
SUMMARY OF THE INVENTION
This object is accomplished with a fan of the generic kind in accordance with the invention in that the drive motor and the control unit are arranged in a common housing, and in that the housing has air vents for passage of a flow of cooling air generatable by the fan wheel, and a heat sink of the control unit is arranged at at least one air vent.
In accordance with the invention, the drive motor and the control unit form a common structural unit. This has the advantage that there is a significantly lower space requirement for the electric fan. Moreover, the electric fan is characterized by very good electromagnetic compatibility, as the control unit is arranged immediately adjacent to the electric motor and is surrounded together with it by a housing, with the aid of which an emission of electromagnetic interference is reliably preventable, as is also an influencing, in particular, of the electronic control unit by external electromagnetic radiation fields.
A further advantage of the design according to the invention is that a separate power supply line between the control unit and the drive motor is dispensed with. This power supply line is a main cause of electromagnetic interference. In addition, the compact design of the electric fan simplifies its handling and results in reduced susceptibility.
In accordance with the invention, provision is made for a flow of cooling air to be generatable by the fan wheel and to be passable through air vents of the housing. Heat dissipation is thereby ensured, so that in spite of the arrangement of the control unit and the drive motor in a common housing, reliable operation is guaranteed. Here provision is made in accordance with the invention for a heat sink of the control unit to be arranged at at least one air vent of the housing. The heat sink is thus directly exposed to the flow of cooling air generatable by the fan wheel, so that, in particular, the control unit does not undergo inadmissible heating during operation of the electric fan. The arrangement of the heat sink at an air vent of the housing makes it possible for the heat sink to be targeted with a flow of cooling air.
The arrangement of the at least one heat sink at an air vent of the housing also ensures that the flow of air generated by the fan wheel and oriented substantially parallel to the axis of rotation of the fan wheel remains uninfluenced by the cooling of the drive motor and the control unit. The flow of air can thus be used completely for cooling, for example, a drive unit of a motor vehicle without coming into contact with cooling elements of the drive motor or the control unit, which would result in a heating of the flow of air and hence in a reduction of the effective cooling performance of the fan. Moreover, the flow of air is not impeded, for example, deflected or partly faded out by cooling elements of the drive motor or the control unit. Instead, a separate flow of cooling air is used for cooling the control unit and the drive motor and like the flow of air provided for cooling external units, this is generated by the fan wheel but extends mainly inside the housing.
A particularly effective cooling of the housing interior is achievable in an advantageous design by the flow of cooling air having a flow section extending inside the housing and oriented substantially coaxially with the axis of rotation of the fan wheel. For example, provision may be made for the flow section oriented coaxially with the axis of rotation to pass virtually through the complete housing in the longitudinal direction thereof, so that both the electronic control unit and the drive motor are subjected to the flow of cooling air and thereby effectively cooled.
Alternatively and/or additionally thereto, provision may be made for the flow of cooling air to have a flow section inside the housing which is oriented substantially radially in relation to the axis of rotation of the fan wheel. This enables, in particular, guidance of the flow of cooling air inside the housing in such a way that the flow of cooling air enters and/or leaves the housing radially, to extend substantially coaxially with the axis of rotation of the fan wheel inside the housing.
It is of advantage for at least one heat sink to be arranged in the area of the radially oriented flow section of the flow of cooling air. In relation to the axis of rotation of the fan wheel this enables a particularly short structural design of the electric fan, as the heat sink can be arranged at the same level as the housing in relation to the axis of rotation.
In a particularly preferred embodiment of the fan according to the invention, provision is made for at least one heat sink to be arranged in the area of an air inlet opening through which the flow of cooling air is conducted into the housing interior. A particularly effective cooling of the heat sink and hence also of the electric components of the control unit thermally connected thereto is thereby ensured as the flow of cooling air is at its lowest temperature when entering the housing interior.
Alternatively and/or additionally thereto, provision may be made for at least one heat sink to be arranged in the area of an air outlet opening through which the flow of cooling air is conducted out of the housing interior. In such an embodiment, the flow of cooling air can first come into contact with the drive motor and the electric components of the control unit inside the housing and then pass over the heat sink at it exits from the housing.
As explained hereinabove, the heat sink is preferably arranged at an air vent which is arranged on a wall area of the housing surrounding the drive motor and the control unit in a circumferential direction.
It is expedient for the heat sink to have cooling fins, the surface normal of which is oriented substantially perpendicularly to the axis of rotation of the fan wheel. The cooling fins are preferably oriented parallel to one another and receive the flow of cooling air between them.
To ensure a particularly large contact surface between the drive motor and the flow of cooling air, provision is made in a preferred embodiment of the invention for at least one heat sink to be arranged at an air vent positioned adjacent to an end wall of the housing, and for the housing to have a further air vent in its end area remote from the end wall. This makes it possible for the flow of cooling air to pass through virtually the complete housing in the longitudinal direction thereof. Here it is particularly expedient for the heat sink to be arranged at an air inlet opening of the housing as this ensures a particularly effective cooling, in particular, of the control unit.
To generate the flow of coo
Gold Matthias
Herke Dirk
Hoenig Frank
AFL Germany Electronics GmbH
Freay Charles G.
Lipsitz Barry R.
McAllister Douglas M.
LandOfFree
Electric fan does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electric fan, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electric fan will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3221417