WO2010022746A1

WO2010022746A1 - Measuring device for the measure of the position of fluid-driven actuators with regulation

Info

Publication number: WO2010022746A1
Application number: PCT/EP2008/006979
Authority: WO
Inventors: Gianfranco Lucignani
Original assignee: Navalimpianti S.P.A.
Priority date: 2008-08-26
Filing date: 2008-08-26
Publication date: 2010-03-04

Abstract

Measuring device of the position of fluid-driven actuators for vessels, in particular ships and floating or marine systems also diving systems, of the type insertable/inserted in a pressure line where said actuator (NVI) are installed, of the type that includes a pressure line (P) from a fluid-dynamic station and one return line (T) to said station to connect at least one valve actuator (A-B) having: a) at least one flow sensor (FS) inserted in the pressure line to be checked (P) of the fluid-dynamic station; b) at least one differential sensor (DPS), inserted between said pressure line (P) and the return line to be checked (B) after one operated said actuators and before reaching said fluid-dynamic station (T); c) said pressure line (P) and said return line (B-T) being intercepted by distributor electro-valve between said flow sensor (FS) and said differential sensor (DPS); d) downstream of said distributor electro-valve being inserted one flow meter (FSE) on said return line (B-T); e) a microprocessor system associated to said flow sensor (FS), said differential sensor (DPS) and said turbine counter (FSE) for detecting, calculating and supplying identification parameters about the position and other values about working anomalies.

Description

DESCRIPTION

MEASURING DEVICE FOR THE MEASURE OF THE POSITION OF FLUID- DRIVEN ACTUATORS WITH REGULATION

Technical Field Object of the present invention is a measuring device for the measure of the position of fluid-driven actuators with regulation according to the parameters of the pre-characterizing part of the main claim.

Background Art

In the present state of the art it is well known that vessels, in particular ships, a plurality of servo-control devices is present, whose possible faults and anomalies can also cause serious troubles.

The intervention quickness, e.g. on repairing, is essential.

Its quickness and immediacy result from a fast detection of the location of the fault.

Currently devices of such conception are extremely complex, expensive, little reliable.

The aim of this invention is to realize a measuring device for the measure of the position of fluid-driven actuators in an efficient way.

Interconnected aim and objective are to realize a device that allows in an easy, fast and trustworthy way the indirect measuring of the intermediate or final positions, of actuators with known capacity driven by a fluid under pressure.

Solution to the problem

The problem is solved by the characteristics of the main claim.

The sub-claims represent preferred solutions.

Advantages This way shows the advantage of

- identifying the break of a line when it is in pressure;

- detecting the internal blow-by of the fluid in the dispenser or the internal leakage of gasket of the related actuator or the uncontrolled manoeuvre of the actuator due

CONFIRMATfON COPY to mechanical reaction.

- therefore identifying in a more trustworthy, practical and functional way the fault or mechanical interference of the actuator;

- any other characteristic deriving from the combination of the above said functionalities.

Description of the invention

The invention will be now better explained by means of the enclosed figures in which:

Fig. 1 represents the structural-operative scheme of the indicator inserted in the fluid circuit.

Fig. 2 represents in a schematic view in transparency the flow sensor (FS) on line

P of Fig. 1.

Fig. 3 represents the differential pressure sensor (DPS) between lines A and B of

Fig. 1. Fig. 4 represents the turbine (FSE) on line T of Fig. 1.

Fig. 5 represents the block diagram of the indicator according to Fig. 1 and according to the present invention.

Detailed description of the device

The indicator as in the figures is an element consisting of two parts: a) a mechanical part that allows to detect the transit of the fluid, its direction and the passed quantity; b) an electronic type detection and measuring part that provides the conversion of the signals referred to in the previous point to obtain a direct measurement on the same device and the repetition of the signal at a distance; The device is meant to be inserted on the control line of the simple or double acting actuator that moves in the two directions the actuator that controls the operated member, in this case a valve is shown (Fig. 1).

More in detail, this device is inserted in the point where the directional valve (distributor) is placed; such valve is shown, in this case, with an electric control, but its control can alternatively be of the electric, fluid-driven or pneumatic type. According to Fig. 1 one can observe that the arm named P is the arm in pressure downstream of the fluid-driven station; the arm named T is the return arm that discharges in the tank of the station.

Depending on the position of the distributing electro-valve, the arm P is connected to the arm A or B of the actuator, allowing the opening or the closing of the valve. Simultaneously, the arm of the actuator that is not connected to the arm P, is connected to the arm T, to allow the return of the fluid into the tank. The position indicator, indicated as NVI in Fig. 1, allows to know the state of the valve based only on the knowledge of the fluid flows in the arms P and T and of the differential pressure between the control lines of the actuator A and B. This solution allows saving and simplicity with respect to a system that needs the installation of electric cables on the valve. Moreover the use of the signals coming from the three sensors and their interpretation, entrusted to the microprocessor, greatly increase the precision and the trustworthiness of the measurement with respect to currently used systems that generally are based on one or two volumetric sensors. Particularly the application in the field of the position control of valves allows to obtain the accurate measurement even in the case in which they are immersed in a fluid and with only two interconnection pipes.

The signals generated by the sensors of the indicator NVI are acquired and processed by a microprocessor that returns a value (in the range between 0 and 100%), visible on a display that indicates the continuous variation of the actuator's position, furthermore the indications of the actuator at the end of the stroke and moving and, at the exit, electric signals of the same information. Working principle Concerning fluidics, the position indicator NVI is based on 3 components: a flow sensor (FS) installed on the line P, a differential pressure sensor (DPS) installed between lines A and B and one volumetric turbine counter (FSE) installed on the line T.

The flow sensor FS detects the presence of the fluid in motion on the line P, the differential pressure sensor DPS allows to know if the pressure is higher in the arm A or B while the turbine FSE works as a volumetric counter in channel T. The signal generated by the flow sensor (FS) depends on the position of a cursor that is submitted to the dynamic pressure of the fluid in delivery and countervailed by an opportune load spring. The position of the cursor, shifted by the fluid flow with respect to its off-position, is revealed by a magnetic (or alternatively optical) signal as disclosed in Fig. 2. The purpose of this sensor FS is to reveal when the fluid flow starts which causes the manoeuvre of the actuator; when the latter reaches the extreme mechanical position, the flow ceases determining the restoration of the off-status of the sensor FS; it therefore determines the measuring window of the volumetric sensor T in order to be able to compensate the volume variations of the crossing fluid caused by gas expansion (possibly present in the fluid) or those due to thermal ranges. The permanence of the reading the flow sensor (FS Fig. 2), if the volumetric turbine sensor (FSE Fig. 4) doesn't give any signal, evidences a loss in the connecting lines to the actuator on the arm that is indicated by the differential pressure sensor (DPS Fig. 3), such discrepancy is indicated to the operator by the microprocessor.

The differential pressure sensor (DPS) operates on the alternative pressure difference in channels A and B that make it move in its seat. The sensor DPS, represented in Fig. 3, is equipped with a rubber o-ring (0-ring); this ring ensures a perfect tightness between the two arms A and B controlling the actuator, and moreover, for static friction, ensures that the cursor stays in its last reached position also in case of break-off of the pressure on both arms, therefore this information allows to "remember in which direction the last manoeuvre of the actuator has been carried out.

The position of the cursor, shifted by the fluid flow with respect to its off-position, is revealed by a magnetic (or alternatively optical) signal as disclosed in Fig. 3. The puφose of this sensor is to allow the counting of the volume revealed by the volumetric sensor FSE in the correct direction, that means to increment or decrement the current value.

The turbine volumetric sensor FSE, shown in Fig. 4, measures the amount of fluid that returns from the actuator chamber placed in discharging, such configuration allows to avoid errors due to the decompression of the fluid in pressure.

It consists of a turbine operated by the passage of the fluid and its number of revolutions is widely practically linear with it.

An optical (or magnetic) sensor detects the number of pulses generated during the manoeuvre of the actuator and it sends them to the microprocessor that carries out the evaluation (counting) in the correct direction basing on the position of the other two sensors FS and DPS.

The electronic card parameterizes this value to give in output and on the display the actuator's position and therefore the valve's position.

Aim of the sensor FSE is to generate a number of impulses in one second proportional to the fluid quantity that is crossing it; it therefore originates a flow signal that, being opportunely integrated by the microprocessor, gives the measurement of the fluid volume that was shifted by the actuator towards the arm

T by the fluid pressure generated in P and therefore to the mechanical position of the actuator itself. The microprocessor provides carrying out a series of evaluations on the base of three sensors FS:

- if the flow sensor FS is excited and the turbine FSE is moving, it means that the actuator is actually operating; - the microprocessor increments or decrements the current value based on the signal of the sensor DPS that determines the flow direction of the fluid and therefore of the actuator showing the relative value on the display;

- when the actuator arrives to mechanical beat, turbine FSE stops because the flow in the arm T ceases;

- flow sensor FS continues to remain excited because the fluid has still to reach the static pressure of the station, compressing in the line; this is the phase defined as "COMPRESSION".

The flow sensor FS returns to the rest state when the pressure on the line is very near to the maximum one of the station;

- reversing the flow direction, the combination and the meaning of the sensors do not change with the exception of the counting direction which is shown on the display.

An intrinsic advantage of the system consists in the possibility to carry out an advanced management of breakdowns that are memorized by the microprocessor to allow the maintenance staff to diagnose and, where the software of the supervisor system allows it, to inform the operator about the type of possible fault giving effective criteria for the evaluation of the safety of the actuators placed under the control of indicators NVI. To an indicative and not a limitative title, the microprocessor identifies the following types of breakdowns:

I - the breaking of a line when it is in pressure (activation of the sensor FS only without activation of FSE).

II - the internal blow-by of the fluid in the dispenser or the internal leakage of gaskets of the actuator or the uncontrolled manoeuvre of the actuator because of mechanical reaction (activation of FSE without activation of FS).

III - the fault or mechanical interference of the actuator (FSE counts less than the due when FS returns to rest position). In this way the device allows in a simple, effective, safe and fast way, to measure indirectly the positions, intermediate or final ones, of actuators with known capacity driven by a fluid in pressure on the ship.

Claims

1.- Measuring device (NVI) of the position of fluid-driven actuators for vessels, in particular ships and floating or marine systems also diving systems, of the type insertable/inserted in a pressure line where said actuators are installed, of the type that includes a pressure line (P) from a fluid-dynamic station and one return line (T) to said station to connect at least to one valve actuator (A-B) characterised in that it includes: a) at least one flow sensor (FS) inserted in the pressure line to be checked (P) of the fluid-dynamic station; b) at least one differential sensor (DPS), inserted between said pressure line (P)- (A) and the return line to be checked (B) after one operated said actuators and before reaching said fluid-dynamic station (T); c) said pressure line (P) and said return line (B-T) being intercepted by distributor electro-valve between said flow sensor (FS) and said differential sensor (DPS); d) downstream of said distributor electro-valve being inserted one flow meter (FSE) on said return line (B-T); e) a microprocessor system associated to said flow sensor (FS), said differential sensor (DPS) and said turbine counter (FSE) for detecting, calculating and supplying identification parameters about the position and other values about working anomalies.

2.- Device according to claim 1 , characterised in that said flow counter is of the turbine type.

3. - Device according to claim 1 and/or 2, characterised in that it is provided with a sensor to detect the number of pulses generated during the actuator's manoeuvre and to send them to the microprocessor that carries out the evaluation / counting in the correct direction basing on the position of said two differential and flow sensors (FS, DPS), this value being parametrizable by an electronic card to give as output the position of the related actuator of the respective valve.

4. Method for the measuring of the position of an actuator using a device according to claim 1 and/or 2 and/or 3, characterised in that it uses said microprocessor in order to provide the execution of a series of evaluations based on the three sensor FS by means of the following steps: a) if said flow sensor (FS) is excited and said counter (FSE) is moving, it means that the actuator is actually operating; b) the microprocessor increments or decrements the current value based on the signal of said differential sensor (DPS) that determines the flow direction of the fluid and therefore of the actuator showing the relative value at the exit; c) when the actuator arrives to limit-stop position said counter (FSE) stops because the flow in the return arm (T) ceases; d) said flow sensor (FS) continues to remain excited because the fluid still has to reach the static pressure of the station, compressing in the line; this is the phase defined as compression; e) said flow sensor (FS) returns to the rest state when the on-line pressure is very near to the maximum one of said fluid-dynamic station; f) reversing the direction of the flow, the combination and the meaning of the sensors do not change with the exception of the counting direction that is shown at the exit.

5.- Vessel including at least one device according to any of claims from 1 to 3.

6.- Vessel including at least one device operating according to the characteristics of claim 4.