Electrically driven air pump

Details Electrically driven air pump Electrically driven air pump

1999-11-24

2001-01-23

Walberg, Teresa (Department: 3742)

Pumps

With muffler acting on pump fluid

Reexamination Certificate

active

06176689

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an electrically driven air pump, for example, for motor vehicles.
BACKGROUND AND PRIOR ART
As described in DE 44 38 750 A1, there is a problem in such pumps in that they produce high operating noise, which is objectionable for the vehicle passengers. A principal reason for the high operating noise is the stimulation of the resonant frequency of the individual housing parts due to the pulsation transport of air.
SUMMARY OF THE INVENTION
An objection of the invention is to provide an electrically driven air pump, which has substantially reduced operating noise.
A further object of the invention is to provide an electrically driven air pump which substantially reduces the pulsation transport of the air.
In order to achieve the above and further objects, the invention provides an electrically driven air pump comprising a housing containing an electric motor and a pump mechanism driven by said electric motor. The pump mechanism includes an impeller having impeller channels which convey air outwardly to an annular channel for delivery of the air to a discharge connection member. A member closes flow of air from the impeller channels to said annular channel except for a defined opening through which controlled flow of air from the impeller channels to the annular channel takes place.
In this way, a defined introduction of the air flowing from an impeller channel into the annular channel is effected. The air does not pass outwardly in an impact-like manner from the air discharge member, but first flows through at least a portion of the annular channel. In this way, the transfer of air flow between two adjacent impeller channels occurs gently and free of pulsation and the desired air throughput can be controlled without further manipulations according to the user's requirements.
By providing the defined opening with special inlet and outlet profiles, a particularly gentle air flow passage is produced from the impeller channels to the annular channel.
A particularly simple embodiment is obtained by providing least one cam disk between the impeller channels and the annular channel and forming said defined opening as a recess in the periphery of the cam disk.
In this way, functional parameters such as pressure and throughput of conventional air pumps can be adapted in a simple and cost-favorable manner. If the cam disk is arranged in an adjustable, movable manner, it also offers the advantage that an adjustment of the pump parameters can be achieved by a displacement of the cam disk. Thus, for example, a displacement of the defined opening in the direction of the air discharge member produces a reduction in the delivery pressure. By a corresponding control of the cam disk, an adaptation of the pump parameters during use is also made possible. If two cam disks are used in a superimposed arrangement, it is additionally possible to vary the size and contour of the defined opening and thus vary the air throughput.
It has proven particularly advantageous is the length of the defined opening corresponds to between one and two times the width of an impeller channel. Together with the contour configuration, this provides for an optimal transport flow through the instantaneously active impeller channel as well as for a gentle passage to the following annular channel. In order to be able to utilize the annular channel in a fully effective manner as a diffuser, the annular channel has a progressively increasing cross-section in the air flow direction to the discharge member.


REFERENCES:
patent: 5875562 (1999-03-01), Fogarty
patent: 6036434 (2000-03-01), Ray et al.
patent: 6074554 (2000-01-01), Ray et al.
patent: 4438750 (1996-05-01), None

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