Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
1999-03-04
2001-05-15
Lopez, F. Daniel (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
C415S055500
Reexamination Certificate
active
06231300
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a peripheral pump having a driven rotor, which rotates in a pump casing and in which a ring of blades is formed in each of its end sides for the purpose of delivering a liquid from an inlet duct to an outlet duct, and having annular ducts, which are formed in the pump casing on both sides in the region of the blades and, together with blade chambers between the blades, form delivery chambers which face one another, the rotor, in its radially inner region and in the region of its circumferential edge, facing toward the pump casing at a slight distance therefrom so as to delimit a sealing gap, and the blades, as seen in the direction of rotation, rising from the central region of the rotor toward the end sides.
2. Background of the Invention
Such peripheral pumps are often used to deliver fuel in a fuel tank of a motor vehicle and are therefore known. In this case, the delivery chambers are separated from one another by a central web arranged in the center of the rotor. When the rotor rotates, the blades generate in the delivery chambers a circulating flow which runs transversely to the direction of movement of the blades. On both sides of the rotor, this circulating flow runs from inlet ducts which are arranged on each side in the pump casing to the outlet ducts. A sill, which interrupts the circulating flows, is arranged in each of the annular ducts of the pump casing, between the outlet ducts and the inlet ducts. This peripheral pump is maintenance-free and has a high level of efficiency. The form of the blades in which they rise from the central region of the rotor toward its end sides reduces impact losses which are caused by the liquid striking the front side or flowing around the blades. These impact losses always occur when the liquid to be delivered passes from the annular ducts into the region of the rotor. Furthermore, this design of the blades accelerates the liquid, when it enters the annular ducts, to a velocity which initially, as seen in the direction of rotation of the rotor, is higher than the velocity of the blades. Then, the velocity decreases in the direction of rotation of the rotor, while the velocity transverse to the direction of rotation increases. Consequently, the circulating flows are in the form of a lance directed in the direction of rotation of the rotor, leading to a high delivery pressure of the peripheral pump.
A drawback of the known peripheral pump is that it has two inlet ducts and two outlet ducts. This desien leads to an unnecessarily high installation outlay on the peripheral pump. Furthermore, owing to its two delivery chambers which are separated from one another by the central web, the peripheral pump has a large structural volume.
Axial flow peripheral pumps having a single outlet duct and a single inlet duct have already been disclosed, in which pumps the liquid flows over from one delivery chamber to the other delivery chamber. In this case, the liquid flows through the rotor in a radially outer region of the blade chambers. However, this design leads to an unfavorable circulating flow profile which has to be diverted by guide elements on the rear sides of the blades. These guide elements are also intended to reduce the impact losses on the inlet side. However, these guide elements cause friction losses and take up a considerable portion of the volume of the delivery chambers. As a result, the peripheral pump has a lower delivery volume and a lower delivery pressure compared to other peripheral pumps.
SUMMARY OF THE INVENTION
The invention is based on the problem of designing a peripheral pump of the type mentioned at the outset in such a way that it has a structural volume which is as small as possible while simultaneously exhibiting a high delivery volume and a high delivery pressure.
Pumps are also known in which the liquid flows over through an aperture between two adjacent delivery chambers (WO-A-92/90457, U.S. Pat. No. 5,409,537). The drawback of these pumps consists in the fact that this flowing over interferes with the circulating flow in the delivery chambers, and as a result the delivery volume and the delivery pressure are reduced.
According to the invention, this problem is solved by the fact that in the region of two mutually facing blade chambers of the blades there is a communicating passage for the liquid to flow over, and that the inlet duct is connected to one delivery chamber and the outlet duct is connected to the other delivery chamber.
Owing to this design, flow passes through the peripheral pump axially via a first delivery chamber and a second delivery chamber, and the pump has in each case only a single inlet duct and a single outlet duct. The peripheral pump can therefore be fitted, for example in a fuel tank, with particularly little outlay. The rotor does not have a central web dividing the delivery chambers from one another, so that the peripheral pump is of particularly narrow design. The peripheral pump according to the invention has a particularly high delivery volume, since the blade chambers are not constricted by guide elements. Owing to the communicating passage between its delivery chambers, the friction losses within the circulating flow during a transition from the first delivery chamber into the second delivery chamber are kept particularly low. Thus the liquid can flow, virtually without interfering with the circulating flow, from the first delivery chamber into the second delivery chamber, leading to a particularly high delivery pressure and to a particularly high efficiency of the peripheral pump according to the invention. The low level of interference with the circulating flow has an advantageous effect particularly for hot liquids with a high vapor pressure, since in the event of the circulating flow being interfered with or broken up, they tend to form vapor bubbles which reduce the delivery pressure and cause cavitation damage to the rotor. Furthermore, owing to the low friction losses, the liquid to be delivered is scarcely heated.
If the delivery chambers have a circular cross section in the region of the blade chambers, the friction losses are particularly low.
The impact losses when the circulating flow enters the blade chambers can be limited to a minimum if, according to another advantageous refinement of the invention, the blades, as seen in the direction in which the rotor moves, rise, by an angle of 5 to 45° with respect to the line perpendicular to the surfaces of the end sides of the rotor, from the central region of the rotor toward the respective end side.
Even at a low speed of the rotor, the peripheral pump according to the invention achieves a particularly high delivery pressure if, according to another advantageous refinement of the invention, the blades, as seen in the direction in which the rotor moves, rise, by an angle of 10 to 20° with respect to the line perpendicular to the surfaces of the end sides of the rotor, from the central region of the rotor toward the respective end side.
At low speeds, it is very easy to produce a lance-like circulating flow which is directed in the direction of rotation of the rotor if, in accordance with another advantageous refinement of the invention, the blades, as seen in the direction in which the rotor moves, rise in the form of a parabola from the central region of the rotor toward the end sides.
Resonant vibrations which occur at specific speeds of the peripheral pump and viscosities of the liquids and lead to disturbing noises, can easily be avoided, according to another advantageous refinement of the invention, by positioning the blades at different angular spacings with respect to one another.
A small structural depth and easy manufacture are provided if the communicating passage is formed by an overlap between the circular delivery chambers.
The liquid flows particularly easily from the first delivery chamber into the second delivery chamber if the communicating passage produced by the overlap of the delivery chambers, according to another adv
Schmidt Christoph
Werner Thomas
Wilhelm Hans-Dieter
Lopez F. Daniel
Mannesmann VDO AG
Mayer Brown & Platt
Woo Richard
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