Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
1999-08-06
2001-09-11
Walberg, Teresa (Department: 3742)
Pumps
Motor driven
Electric or magnetic motor
C415S052100
Reexamination Certificate
active
06287093
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is based on a side-channel pump having an intake cover for a side-channel pump, which is used in pumping fuel in a motor vehicle. The intake cover has a side channel, extending radially around a pivot axis in the intake cover, and also has a top side and an underside and a first opening in the underside for an intake channel of the side channel. The fluid flowing through the side-channel pump flows via the intake channel through the side channel to an outlet from the side channel.
One intake cover and one design of a side-channel pump are known from German Patent Disclosure DE 195 04 079 A1. An axially extending intake channel discharges into a side channel that extends in the cover, in which side channel, as a result of pulse exchange events with a bladed rotor about its pivot axis, a pressure buildup takes place as far as the outlet neck. The blading of the rotor is placed obliquely relative to the pivot axis in such a way that toward one face end of the rotor it is leading in the circumferential direction of the rotor.
German Patent Disclosure DE43 43 078 A1 in turn describes a unit for pumping fuel by means of a side-channel pump. A side channel in an intake cover of the side-channel pump has a cross-sectional reduction by the factor of 0.5, in order to act as a compression channel. This cross-sectional reduction extends over an angular range of approximately 90 to 130 , referred to a beginning of the side channel; if there is a linear reduction in the cross section, then there is a transition via a small step to the remaining constant side channel cross section. A progressive cross-sectional reduction contemplated there has a continuous reduction in the side channel depth and side channel width without any step. The cross-sectional reduction is than attained via a reduction in the side channel depth and a progressive reduction, for instance, in the side channel width over the angular range of 90 to 130.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a side-channel pump which avoids the disadvantages of the prior art.
In keeping with these objects, one feature of present invention resides, briefly stated, in a side-channel pump, in which the side channel width in the top side over an angular range having a first angle referred to the reference line of 0 and 20 is constant as far as an outlet from the side channel.
The side-channel pump with an intake cover, as defined by the invention, has the advantage over the known prior art that the pump efficiency and hot gasoline performance are improved. To that end, the side channel has a constant side channel width in the top side in the top side in an angular range having a first angle &phgr; referred to a reference line, that extends through the pivot axis and through a contact point at the beginning of the side channel, of 0 , preferably approximately 5 , and at most 20 as far as the outlet from the side channel. Previously, the attempt had been made to avoid the formation of turbulence structures that cause loss and an unintended separation of the flow in the side channel by narrowing the side channel width steadily down to a constant value over a wide angular range. The proposed geometry, conversely, attains a higher suction level, for instance, because even at least in the immediate vicinity of the beginning of the side channel, the side channel has the most constant possible width. The constant channel width, which as a result is disposed near the first opening for the intake channel, assures that in the region of an inlet flow of fuel into the side channel, a development of braids of turbulence in the flow is avoided. Hydraulic losses and local negative pressure zones, which could otherwise lessen the efficiency or, because of an increased vapor pressure in the case of hot gasoline in the summer could cause the danger of cavitation and thus blockage of the blade cross section, are decisively reduced.
It is also possible, because of the constant width of the side channel, that upon the inflow of fuel through the intake channel, a development of a detachment bubble, from the high suction occurring in an outer region of the inflowing fuel in the case of a dual-flow side-channel pump, toward a pumping step located opposite the intake channel, is suppressed.
One advantageous refinement provides that the side channel has a center line whose radius to the pivot axis remains constant, at the latest beyond the first angle &phgr;=15 . The center line is the line in the side channel that results when each width of the side channel is divided in half. The side channel as a result already extends circumferentially at the intake channel without the imposition of an additional radial flow direction on the flow as would be the case if the center line radius were not constant. As a result, an inlet flow pointing radially inward toward the pivot axis between the intake channel and the side channel is averted. It is therefore advantageous for the center line radius to already be constant at &phgr;=0.
It is also preferred that the side channel have a constant width in the top side no later than beyond the first angle &phgr;=5. The side channel width is located in the face of the top side of the intake cover that has the side channel which is open at the top. Below the top, or in other words between the top and the underside, the side channel in one version has a greater side channel width. However, this width preferably also drops, within at most &phgr;=20 to 30 of the first angle, to the constant side channel width in the top side. In this way, by a kind of funnel effect, a pressure buildup is again made possible, which has a favorable effect on the inflow of the opposed pumping step of a dual-flow side-channel pump. In a further feature, this effect is reinforced by a transition from the first opening into the side channel via the intake channel. The intake channel below the plane through the top side has an increasingly slender transition that conforms to the side channel. This transition can already begin at the first, preferably round opening. Below the underside, the side channel and the intake channel with its transition therefore still have a greater width than in the topside. This kind of favorable flow course is further promoted by the fact that the first opening for the intake channel of the side channel, as well as the intake channel itself and the transition to the side channel, are designed to be as circular as possible.
It has proved to be a further advantage if an outer region of the beginning of the side channel, with the most constant possible width, has an initial radius R
A
relative to a side channel radius R
SK
of approximate R
A
=0.4 R
SK
to R
A
=1.1 R
SK
. The side channel radius R
SK
is defined as the radius which maximally determines the geometry of the side channel in the angular range of constant side channel width. This will be seen in more detail below from the drawing. A separation flow in the region of the beginning of the side channel is averted by this kind of initial radius R
A
. At the same time, this makes for a smooth transition of the inlet flow into the side channel, so that there is no disturbance to circulation with the attendant hydraulic losses. A further advantage of such a radius is that reverse flows are prevented. In that case, a blade chamber inflow into the blading of the side-channel pump is then unimpeded by collisions.
A development of turbulence braids in the inlet flow through the intake channel at the transition to the side channel is also averted by the provision that the first center point of the first opening is located radially closer to the dx than the center line along the side channel. Not only hydraulic but even local negative pressure zones are thus prevented, with the advantageous effects described above with regard to hot gasoline. A reduction in collision losses in the blade chamber inflow is also reinforced in cooperation with the first open
Huebel Michael
Strohl Willi
Robert & Bosch GmbH
Robinson Daniel
Striker Michael J.
Walberg Teresa
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