Device metering and measuring quantities of liquid

Details Device metering and measuring quantities of liquid Device metering and measuring quantities of liquid

1998-10-28

2001-03-06

Patel, Harshad (Department: 2855)

Measuring and testing

Volume or rate of flow

Expansible chamber

C073S861830, C417S313000, C222S071000

Reexamination Certificate

active

06196065

ABSTRACT:

FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a device for metering and measuring quantities of liquid, in particular in a pump for liquid fuel.
A device of this type is known in the prior art. In the case of the known device, use is made of one or more volume meters in the form of piston displacement meters, each volume meter being assigned a valve. The valve and volume meter are flanged together by means of pipes, just like valve and liquid supply. The liquid supply comes from a pump which pumps the liquid fuel from a reservoir tank. The known device not only requires a great deal of space, it is also expensive to produce. Furthermore, the known device ought to be improved in respect of its operating reliability.
SUMMARY OF THE INVENTION
It is an object of the invention to improve a device of this type in terms of production technology and use technology and to develop it in terms of reliability of use.
The invention is distinguished by a small physical size, The device is also simplified in terms of manufacturing technology, as a result of the block design. The housing is shaped by material-removing machining, for example drilling or milling, from the ends and/or broad sides.
In this case, the housings assigned to the volume meters can be machined exclusively on the ends. In addition, the sealing arrangement is simplified by the direct joining together of the individual blocks, with the result that the end of the block carrying the screw-spindle arrangement can be covered by the broad side of the valve block. The bearing chambers for the axial bearings of the spindles are thus covered optimally in a sealing manner. A favorable vibration behavior has also been shown, inter alia, particularly when the device according to the invention is used above a delivery pump, the device being borne by the delivery pump itself. It has furthermore been shown that the device according to the invention requires virtually no recalibration and yields quantities of liquid which are dimensionally accurately metered to a high degree, and measures them with high dimensional accuracy. Pipe connection lines between the individual housing blocks can be completely dispensed with since the housing openings are sealed in a simple manner owing to the housing surfaces lying directly on top of one another. It has likewise turned out to be advantageous that the valves are formed both by the housing and by valve heads placed onto valve connection openings, the valve heads being assigned the control elements for the valves. In an advantageous manner, the second housing blocks, in which the spindles are arranged, are seated by their ends on a broad side of the first housing block. This makes it possible to form the preferred U-shape of the overall housing. The valve connection openings can be assigned to the ends of the first housing block, with the result that the two valves are situated opposite one another. The housing blocks preferably have a parallelepipedal shape. The ends have a square base area. The valve piston can be designed as a freely moving piston, as a diaphragm or the like, and preferably moves within the separating plane between housing block and valve head, in other words through the valve connection opening. A supply duct which proceeds from the inlet opening, which is preferably closed off by a nonreturn valve, opens out into the valve connection opening. This supply duct preferably opens out into an annular space under the edge region of the piston or of the diaphragm. The annular space encloses the connecting duct which connects the valve to the volume meter. The volume meter preferably comprises two mutually engaging screw spindles through which axial flow takes place and which are subjected to rotary driving by the through-flowing quantity of liquid in accordance with the displacer principle. A device of this type for measuring quantities of liquid is disclosed in DE 41 42 062. One of the two spindles may bear a pulse generator wheel provided with magnets which move back and forth under a magnetic sensor. The pulses generated in the process are fed to a pulse conversion and measuring device in which quantitative values are derived from the electronic pulses and are displayed on a display. The valve heads placed onto the valve connection openings with the interposition of a seal may have solenoid valves as actuating elements. These solenoid valves may in each case form a pilot valve and a bypass valve. The pilot valve opens overflow ducts provided in the valve, so that the valve piston can be shifted into an opening position. When the pilot valve is closed, a return spring ensures that the valve piston or the like is shifted back into a closure position. A bypass valve may be provided in addition to the pilot valve, which bypass valve opens a bypass opening between the supply duct and the connecting duct, thereby enabling sensitive metering of fuels. This is necessary particularly when the device is intended to be used within a pump at which predetermined quantities of fuel can be supplied. The housing block having the screw spindle has two overlapping holes whose internal diameter corresponds to the external diameter of the spindles, with the result that the spindles can rotate freely therein. At the ends of the overlapping holes, the cavity of the housing block widens into chambers having a larger cross section. These cross-sectionally larger chambers form bearing receptacles for the axial bearings of the spindles. The axial bearings of the spindles are preferably ball bearings and are freely accessible from the end of the housing block and are covered by the block wall of the adjoining housing in the assembled state. While one end of the second housing block is covered by the first housing block, the other, opposite end may be covered by a sensor block arranged in alignment with the second housing block. This sensor block then covers the chamber and bears said magnetic sensor which interacts with the axially projecting rotor. An end termination may be formed by the second housing block by means of an axial outgoing line for the metered liquid. In a preferred development of the invention, which has independent character, the measuring block arrangement is mounted above a delivery pump. In this case, the spindles lie in the horizontal direction. The design of the delivery pump is also intrinsically inventive and has independent importance. It is important, in particular, that the delivery pump forms an insert designed as an internal gear pump. This insert enables the essential parts of the pump which are susceptible to wear to be exchanged in a simple manner without the entire housing having to be removed from the pump. The insert has a flanged cap which covers a receptacle opening for the internal gear pump and can be screwed to the pump housing. The delivery pump advantageously has a double gas separator with float-controlled liquid recirculation. The gas separator is fitted inside the pump body and has a relatively small volume yet nevertheless enables even diesel fuel to be dispensed without any bubbles. In this case, it is regarded as advantageous that the gas separator has a total of two cyclones arranged in mirror-inverted fashion, into which cyclones the pumped fuel is introduced and in which, on account of the centrifugal acceleration, the gas components fall back radially inward and can escape upward. Arranged above the cyclone is a displacer chamber in the form of a bell which switches a solenoid valve at an elevated gas concentration, said valve switching off the valves in the measuring block, with the result that the pump initially has only a degassing action. The gas separator preferably has two chambers separated by an overflow edge. A float may be arranged in the second chamber, said float closing off a recirculation opening through which the liquid forming from the condensed gas can be recirculated to the intake end of the pump. The device can also be used in submersible pump operation.


REFERENCES:
patent: 3963146 (1976-06-01), Esbjornsson
patent: 4

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