GB2053485A

GB2053485A - Liquid volume meter

Info

Publication number: GB2053485A
Application number: GB8018820A
Authority: GB
Original assignee: Scheidt and Bachmann GmbH
Current assignee: Scheidt and Bachmann GmbH
Priority date: 1979-06-30
Filing date: 1980-06-09
Publication date: 1981-02-04
Also published as: GB2053485B; FR2460473A1; DK190680A; SE8004775L; NL8002954A; BE883830A; DE2926451A1; DD151807A5; FR2460473B1; CH647864A5

Abstract

The volume meter has pistons reciprocated by the liquid of which the volume is to be metered. The pistons are secured to a crankshaft, rotation of which is signalled by a disc 14 secured to an extension of the shaft. The disc forms part of a pulse generator 14, 15 for counting rotations of the shaft. The number of pulses per rotation is adjustable by a member 16a to compensate for constructional and medium-affected deviations. Preferably at least the pulse generator is mounted in the wet space of the measuring mechanism. <IMAGE>

Description

SPECIFICATION .Volume meter This invention relates to volume meters.

Volume meters with movable separating walls for the measurement of quantities of liquids have been known for many decades in various constructions. As volume meters for dispensing of liquid fuels at petrol stations, piston meters with a plurality, preferably four, pistons have been commonplace. In all constructions the smallest delivered quantity corresponds to at least one cycle of the measuring mechanism, which is driven by the pressure of the liquid to be measured and in turn this drives an indicating or display mechanism, which forms together with the measuring mechanism the volume meter.

According to the present invention there is provided a liquid volume meter comprising means for sensing movement cycles generated by the liquid acting on movable separating walls of the meter, a device for compensating for deviations of the measuring mechanism based on constructional and medium-affected factors, a pulse generator generating a predetermined number of pulses for each movement cycle of said separating walls sensed by the sensing means and an electronic calculator for applying a correction factor taking into account the constructional and medium-affected deviations.

A volume meter embodying the invention will now be described by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a longitudinal section through a volume meter constructed as a piston meter incorporating a compensating device; and Figure 2 is a block circuit diagram of the compensating device.

The volume meter illustrated comprises a housing 1, in which four pistons 2 (only three shown) are slidable in a respective sleeve 3. The pistons 2 are interconnected in pairs by a respective cross-slide 4, the directions of motion of the pairs of pistons all lying in a common plane but the motion of one pair extends at right angles to the direction of the other pair.

Each cross-slide has a bore in which a roller 5 is accommodated. The two rollers 5 are rotatably mounted on a common pin 6 of the crankshaft 7, the ends of which crankshaft are journalled in the housing 1. Each cylinder sleeve 3 of the four pistons 2 is closed at the end remote from the cross-slides by a cylinder head 8. A passage 9 in the housing 8 communicates with the interior of each of the cylinder heads 8.

A rotary control disc 10 cooperates with these passages 9, is fast for rotation with the crankshaft 7 and is mounted within a disc housing 11, which is mounted on the top of the housing 1. This disc housing 11 has an inlet passage 13 and an outlet passage 1 2 for the liquid to be measured. This liquid, under pressure, flows in the direction of the arrows indicated in Figure 1 into the disc housing 11 and from here through the rotary control disc 10 into one of the passages 9.

The fluid flows out of the passage 9 through the cylinder head 8 into the corresponding sleeve 3, in which the pressurized liquid displaces the piston 2 in the direction towards the centre of the housing 1. Since this piston 2 is secured through its crossslide 4 with the co-axially mourited piston, the displacement of the one piston 2 effects by means of the pressurized liquid an outward pressure on the liquid in the cylindrical sleeve 3 of the opposed piston 2 and through the corresponding cylinder head 8 into the corresponding passage 9 and through the rotary disc 10 into the outlet passage 12. This process is repeated cyclically in all four cylindrical sleeves 3 under control of the disc 10.

The displacement of the pistons 2 taking place during the working cycle is transmitted through the cross-slides 4 and the rollers 5 to the pin 6 of the crankshaft 7, which rotates correspondingly once through 3600 for each working cycle. The liquid volume passing during this 36OO rotation corresponds to the measuring space of the meter fitted with four movable separating walls and corresponds thus to the smallest delivered liquid quantity.

The crankshaft 7 carrying the rotary disc 10 projecting upwardly out of the housing 1 into the disc housing 11 is extended upwardly (as shown) beyond the rotary disc 10. The crankshaft 7 carries at the end of the extension a pulseinitiating disc 14, which as shown in Figure 1, is arranged within the wet space of the measuring mechanism. This pulse-initiating disc 14 is a component of a pulse generator 15, which is also shown in the block circuit diagram of Figure 2.

This pulse generator 1 5 is connected in an electronic calculator circuit, of which the components are again shown in Figure 2.

The calculator incorporates an adjustment device 1 6 for applying a correction factor taking account of constructional and medium-affected deviations, a signal processor 1 7 with a connected signal generator 1 8 and a counter 19. The integers 1 5 to 19 are connected to a current source 20 and together control an indicator 21 for displaying, for example, five characters.

By means of the pulse-initiating disc 14 pulses are generated by the pulse generator 1 5 and, in fact, for any given working cycle a predetermined number thereof. This means that each pulse corresponds to a predetermined liquid quantity flowing through the volume meter. In as far as this shows the calibrated measurement of the piston meter, the measured volume per pulse does not correspond to the required value volume, the deviation from the actual volume from the required value volume is given and a correction factor calculated, by which the pulse number per working cycle must be multiplied, in order to compensate for the constructional and mediumaffected deviations of the measuring mechanism of the piston meter. This correction factor is applied by an adjustment device 16 for which there is provided an adjustment member 1 6a.This adjustment member 1 6a is preferably connected only through a pulse conductor with the adjustment device 16.

The pulses applied by the pulse generator 15 corresponding to the working cycle are modified by the adjustment device 16 so that the signal processor 17 supplies such signals to the downstream signal generator that it generates a corrected pulse. These pulses of the signal generator, taking into account the constructional and medium affected-deviations of the measuring mechanism, pass finally to the counter 1 9, which controls the indicating display device 21. This indicating device 21 therefore displays the fluid volume effectively measured by the counter, without it being necessary to adapt the measuring space of the piston meter to the required value and without it being necessary to provide complicated mechanical intermediate drives.

In the diagram of Figure 2, both the piston 2 and the cylinder sleeves 3 as well as the crankshaft 7 are shown diagrammatically. Figure 1 shows, that the pulse generator 15 is moulded into a synthetic-resin block 22 which lies in a recess of the disc housing 11. This synthetic-resin block 22 mounted in the wet space of the measuring mechanism incorporates at least the pulse generator 15. It can also incorporate further components of the electronic calculator, including the counter 19. The volume meter can be arranged as a unit without any display device 21, but connected to one through a pulse connection line 23.

The hereinbefore described meter ensures a reduction in the liability to wear of the constructional parts, avoids the need for additional sealing zones and manual contact for calibration or other purposes in the wet space of the measuring mechanism. The compensating device has few constructional parts, but provides a stepless compensation for the constructional and medium-affected deviations, thereby avoiding the need for calibrated measurement necessitating manual contact in the wet space of the mechanism and without high manufacturing costs being necessary to ensure precision in the manufacture of the measuring chamber. The components of the compensating device of the measuring mechanism do not require additional shaft seals between the measuring mechanism and the indicating mechanism as in previously proposed constructions and furthermore it is unnecessary to couple a particular indicating device to a particular measuring mechanism.

Claims

1. A liquid volume meter comprising means for sensing movement cycles generated by the liquid acting on movable separating walls of the meter, a device for compensating for deviations of the measuring mechanism based on constructional and medium-affected factors, a pulse generator generating a predetermined number of pulses for each movement cycle of said separating walls sensed by the sensing means and an electronic calculator for applying a correction factor taking into account the constructional and mediumaffected deviations.

2. A volume meter according to claim 1, wherein at least the pulse generator is arranged in the wet space of the measuring mechanism.

3. A volume meter according to claim 1 or claim 2 wherein said separating walls are in the form of four pistons slidable within a cylindrical sleeve and interconnected in pairs by cross-slides.

4. A liquid volume meter according to any one of the preceding claims wherein the pulse generator includes a disc connected to the movable separating walls and driven thereby, and means for generating electrical pulses connected to the disc.

5. A volume meter for measuring the volume of a flow of liquid, said meter comprising separating wall means movable under the action of the liquid, means driven by the separating wall means for initiating the generation of pulses related to the movement of the wall means, an electrical pulse generator actuable by the means driven by the separating wall means, means for applying a calibrating correction to the signal generated by the electrical probe generator, signal processor means connected downstream of the calibrating correction applying means, signal generator means connected to the output of the processor means, a counter connected to the output of the signal generator means and indicating or display means connected to the output of the counter.

6. A volume meter substantially as hereinbefore described with reference to the accompanying drawings.