EP0205779B1

EP0205779B1 - Measuring transducer based on the positioning of at least one mechanical revolving element

Info

Publication number: EP0205779B1
Application number: EP86104447A
Authority: EP
Inventors: Vittorio Ponzio
Original assignee: Fabbriche Riunite Misuratori Sacofgas SpA
Current assignee: Fabbriche Riunite Misuratori Sacofgas SpA
Priority date: 1985-04-02
Filing date: 1986-04-01
Publication date: 1991-06-12
Also published as: EP0205779A2; IT1183556B; IT8520195A0; DE3679720D1; ES293322U; ES293322Y; EP0205779A3

Description

The present invention refers to a measuring transducer based on the positioning of at least one revolving element.
According to the invention the device can be of great advantage when applied in the measuring of angles, angular displacements, number of rotations and various indications of a mechanical measuring meter for fluid, gas or electric measurements. At the moment, for instance, the measuring of the number of rotations done by a meter is based chiefly on visual detection. As known, a meter is made up of a group of inter-acting revolving elements, controlled by an operating gear the movement of which is associated to the quantity of fluid or gas passing in a given duct, so to have a correlation between the fluid or gas quantity passing through and the number of rotations, or fractions of rotations done by the revolving elements of the meter. Each revolving element is divided into a predetermined number of zones, each bearing a number. The revolving elements are mated in such a way that as soon as one terminates a complete turn, it causes the rotation at a predetermined angle of the adjoining one. A jig placed in a predetermined position allows the visualization of a constant portion of the revolving elements and the visual indication of the numbers or fractions of rotations done by a group of elements. In the known meters no internal transducer is foreseen for the detection of the number of rotations and their transduction in a suitable electric signal, so as to have a record of the fluid or gas consumption on a memory for subsequent elaborations.
"Electronic Industries", volume 22, No. 6, June 1963, pages F2-F7, F26, F27 discloses a measuring system of angular displacements comprising two encoders, the second of which is a "vernier" of the incremental type exclusively apt to increase the accuracy of the measurement, reading between two subsequent divisions of the first encoder. Being the second encoder of the incremental type, with the photosensing elements offset by 90° with respect to the photosensing elements of the first encoder, the measurements can be carried out only when the disc is in motion.
Therefore, such a system cannot be used to transduce angular measures in meters for fluids and electricity.
US-A-4 142 096 discloses a meter for measuring consumption of water, gas or electricity, which can transmit the stored information in digitized form.
The accuracy of the measurement during the passages by the zero position of each decadic wheel is achieved by means of lever and spring assemblies suitable for carrying the decadic wheel to the right reading position during the transfer.
The fact that the spings must be loaded during the rotation of the mechanism reduces the power of the fluid means, for example gas, which generates the motion, considerably increasing the loss in load of the same, especially at slow rotation speeds.
Aim of the present invention is thus to carry out a device allowing for the transduction of the measurement pertaining to the number of rotations detected by a meter, into an electrical quantity able to be suitably treated, so as to have the most accurate detection, while still permitting a reliable functioning of the mechanical group and foreseeing a transducer intimately connected to the meter already known.
This aim is achieved foreseeing the arrangement claimed in the characterizing part of the independent claim 1.
Preferred embodiments of the present invention are described in the dependent claims.
The special characteristics of the invention will be evident through the specification and drawing enclosed, in which:

Fig. 1 shows a front view of the group to which the transducer according to the invention has been applied;
Fig. 2 shows a detail of the engagement between the two transducers;
Fig. 3 shows a detail of the second transducer according to the invention;
Fig. 4 shows the reciprocal connection of the two transducers subject of the invention and the control devices of the signals detected according to the invention.

With reference to a preferred but not limitative embodiment of the invention, in Fig. 1 we note a meter 10 placed inside a container 9 which is made up of a set of revolving elements 11a, 11b ... 11h suitably mated. As visible from Fig. 1 the revolving elements 11 are mated one to the other by means of gears 21a, 21b, etc. so that at each rotation of the revolving element 11a a partial rotation is caused in the adjoining element 11b, and so on. The mating with the gears 21a, 21b ... 21h is not shown in detail as it is well known. If these revolving elements are divided on the peripheral circumference in ten or more zones, we can have a numerical indication of the number of rotations made by the driving pinion 12. Said driving pinion 12 is in turn connected to a group of gears which can be activated by the passing of a fluid or a gas into a duct. Such a disposition is common to all the meters for instance known for visual detection of the consumption of gas or other energy supplies.
According to the invention, to each revolving element 11a, 11b... 11h, a second transducer formed by a disc 14 used as a first transducer, having openings 25, is associated coupled by means of gears. A disc 14 is shown in detail in Fig. 3.
In Fig. 1 for better clarification only two discs 14 are shown, disc 14c and 14f respectively.
The mating between each disc 14 and the corresponding revolving element 11 takes place by means of gears. Fig. 2 shows an exemplary mating between the revolving element 11c attached to a pinion 13c which engages in the gear 15c, the latter rotating integral to the disc-transducer 14c.
Associated to each codifying disc provided with openings, placed according to a predetermined binary code, a detector is provided, for instance photo-sensors 16, which are to detect the disposition of the openings in the disc section passing in front of them. Each detecting element 16 of the codifying disc 14 sends the signal to a suitable control device 18. Also the position of each revolving element 11 is signalled to the control device 18. The control device 18 is in turn connected for instance to a display 20 or to a suitable interface for the dispatching of the detected signal to a suitable centralized device (Fig. 4).
The second transducer 14 formed by a disc provided with openings 25 is a tranducer, or "coder" of the absolute type working as a dividing "vernier" of the traditional devices. This in the aim to be able to detect the small displacements and to obtain a maximum positioning accuracy of the measuring unit.
The mating between the two tranducers 11 and 14 is made in a particular way in the aim to simultaneously obtain the synchronism in the measuring of the passing instant between the data supplied by the faster transducer and the more roughly measuring one.
According to the invention at the moment of assemblying the group incorporating the "vernier" type transducer, the two transducers are angularly offset so that the "vernier" transducer is delayed in respect to the corresponding signal of the other transducer. In particular the "vernier" transducer must reach the zero delayed of an interval comprised between 1/5 and 1/10 of a division.
The control circuit 18 of the signal suitably synchronizes among them the signals detected by the two transducers and does not change for instance the signal sent to a display 20 or to a subsequent signal-control device before the other transducer as well has reached the commuting point. In this way the real value remains within the fixed tolerance.
In fact the greater the number of the "vernier" divisions the more accurate the tolerance on the measuring. Such a mechanical disposition allows, in lack of electrical feeding, an indefinite storage of the detected data also in the case of measuring variations. The two transducers keep the reached positions.

Claims

A transducer arrangement in a meter for measuring consumption of fluid, e.g. water or gas, or electricity through the measurement of the angular position of mechanical revolving elements comprising:
- first transducers formed by revolving elements (11a ... 11h) which are intermated such that when one revolving element completes a rotation it causes an incremental rotation in the next one;

- second revolving transducers (14a ... 14h) each of which is mechanically mated to a respective first transducer and comprises encoded discs of the absolute type;

- a sensor (16) which detects the angular position of the second transducers (14a ... 14h) and sends signals to a control device (18) connected to a display (20) or to an interface for remote transmission of the signals,
characterized in that
- the encoded discs comprise a multiple number of openings (25) placed according to a predetermined code and to a desired limit of accuracy, such that, in operation, they act as "verniers";

- the mating between first and second transducers is such that the "vernier" indication of the second transducer (14a ... 14h) is delayed with respect to the indication of the first (11a ... 11h);

- said sensor (16) comprises a plurality of individual sensors (16a ... 16h) one for each second transducer;

- further sensors (111a ... 111h) are provided to detect the angular positions of the first transducers (11a ... 11h) and send signals thereof to control device (18).
A transducer according to claim 1, characterized in that said delay is comprised in a 1/5 and 1/10 of interval between the division of the first transducers.
A transducer according to claim 1, characterized in that the control device (18) comprises a synchronizing device of the signals detected by the sensors associated to the first and second transducers.
A transducer according to claim 3, characterized in that the synchronizing device foresees a coinciding and interpreting circuit which controls by addition or substraction the data supplied by the sensors associated to the first and second transducers, so as to supply at the output the measurement reached in the required tolerance.