CN1003397B - Devices for detecting flow and determining flow velocity - Google Patents

Abstract

The device for detecting the flow rate and measuring the flow rate includes a casing 7, which is equipped with a throttling/blocking component 2, which is elastically connected to the elastic support 3, and the strain gauge pressure sensor 14 is installed on the component 3. The output signal of the sensor 14 is sent to a compensating assembly which at least partially compensates the force exerted by the fluid on the throttling/restricting system 1 . System 1 includes components 2 and 3.

Description

Device for detecting flow and measuring flow velocity

The present invention relates to a device for detecting the flow rate and the flow velocity of a medium in a non-rotating system.

The fluid may be a gas, a liquid or any fluid that may be present.

The invention can be widely applied to industrial, agricultural, meteorological and water supply management and scientific research activities related to the fields. In fact, the invention can be used wherever it is necessary to detect the flow of a medium, either to prevent the flow of the medium or to ensure its supply, and wherever it is necessary to determine or measure the flow rate of a fluid.

There have been many solutions to measuring flow rate. One type of solution uses a flow rate meter that uses a rotating member, which may be a paddle or rotating blade structure, that rotates as a result of the flow of the medium, the number of revolutions per minute (rpm) of which is proportional to the flow rate. In another type of solution, the detector consists of a pressure plate displaceable along a horizontal axis perpendicular to the flow direction. The surface of the pressure plate facing the fluid is subjected to a throttling pressure which overcomes a certain gravitational or other restoring force to displace the pressure plate.

The displacement or position of the detector can be transmitted to a display instrument by mechanical means or can be formed as a pneumatic or electrical signal, which can be measured directly or by suitable processing.

A solution belonging to the pressure plate type is disclosed in patent application No. 25356 published in hungarian. The device comprises a throttle member extending into the fluid, the plane of the throttle member being perpendicular to the direction of flow and being secured to one end of a support means, the other end of the support means having a strain gauge pressure sensor secured to the outer surface of an elastically deformable member.

The device disclosed in GB1, 434, 165 is based on the same principle and comprises a throttling element fixed to a resilient support member mounted in a closed transverse branch of the flow duct.

In the device according to HU173,784 there is a device which is acted upon by a fluid and which is equipped with movably supported blades which can be moved easily in mutually parallel or coaxial directions. A corresponding member hinders but does not prevent the displacement of the blade under the action of the fluid.

All these known devices are more or less structurally complex and therefore susceptible to faults or damages, especially in difficult working conditions. Therefore, these devices are not well suited for long-term reliable, continuous use for measurements. The known measuring devices are formed by a predetermined number of throttling or flow-impeding parts, which, in the specific case of only one throttling or flow-impeding part, only enable partial measurements to be carried out. The sensitivity of the measurement is not very ideal, especially at low flow rates.

The structure of the device of the invention aims to eliminate the unfavorable performance in the traditional structure, and provides a flow detection instrument with simpler structure and greatly increased measurement sensitivity, the detection instrument can reliably and faultlessly work under wider working conditions even under difficult conditions, and the detector also combines the working principle of a rotating part and a pressure plate type to detect the flow of a medium and measure the flow velocity of the medium.

The invention therefore consists in a device for detecting the flow and determining the flow rate of a medium, comprising a stationary throttle system displaceable under the action of the medium, sensor means for detecting the force to which the throttle system is subjected and for providing an output signal, and optionally a component for amplifying, transmitting, displaying and recording the output signal of the sensor.

The device according to the invention has the feature that it has a housing, the space in which is partially or completely isolated from the fluid, and that the throttle (or choke) element is fixed in the throttle system and is suitably fitted outside the space in the housing so as to be symmetrical about an axis which coincides with the direction of flow. In addition, the device according to the invention comprises an elastic support for fixing the throttling (or flow-blocking) element and a compensating assembly for compensating, wholly or partially, the forces acting on the throttling (or flow-blocking) element.

The advantages are that: the throttling (or flow-impeding) part is connected in a sealed manner to the space inside the housing, the plane of the throttling (or flow-impeding) part being adjustable with respect to the flow direction in order to adjust the sensitivity of the device.

It is convenient to be: the elastic support consists of a leaf spring extending between the throttling (or flow-resisting) part and the throttling system, and the balance shaft is arranged on the plane of the leaf spring.

In another embodiment of the device, the compensating part of the device is an elastic mechanism or a weight mechanism and an electromagnetic device.

The detection sensor and/or the compensation element can be appropriately fitted in the housing interior space and can be mounted in an electrically insulating manner if necessary.

The solution proposed by the invention is based on the finding that a device based on a combination of rotating-part and pressure-plate devices with a balanced stationary throttle system displaceable by the action of a fluid has the advantages of both the original ways, respectively, as well as other advantages. The solution according to the invention increases the sensitivity of the measurement, which is particularly advantageous in the case of very low flow rates. In addition, the range is also expanded, even reaching 1: 100. The number and size of the throttling or flow-blocking parts of the throttling or flow-blocking system can be made as desired.

In the case of this device, the displacement of the throttling or flow-blocking system is difficult to measure and can be virtually completely eliminated if a compensating element is used, i.e. in the case of a device which uses a stationary throttling (or flow-blocking) system, one simply measures the partial torque at right angles to the balance axis caused by the throttling (or flow-blocking) force of the flowing medium or the (possibly elastic) deformation caused by this torque. In addition, the device is a rigid device with respect to throttling force components in other directions, so that there are virtually no other deformations that could affect the measurement. The deviation or error in the measurement is only 2-3%, i.e. well within the error range of the commonly used measuring instruments, assuming that the balance axis of the throttling (or choked) system deviates from the flow direction by 15-20 °.

Suitably selected embodiments of the apparatus of the invention may be used in underground mining for detecting airflow, continuously measuring instantaneous values of air flow rate, and for telemetrically recording these values from the surface under certain circumstances. This embodiment is described in more detail below, purely by way of example, with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of the present apparatus.

Fig. 2 is a cross-section taken along the plane indicated by line ii-ii.

Referring to fig. 1 and 2, the present device has a throttle system 1 with four throttle (or choke) parts 2, which are connected to a base plate 5 of the throttle system 1 by resilient brackets 3 formed of leaf springs. The flat faces of the leaf springs are mounted adjacent their connection to the respective strain gauge sensors. These sensors are assembled in a suitable circuit, and together constitute a detection signal output section 14 of the present apparatus. The elastic holder 3, the leaf spring bottom plate 5 and the detection signal outputting portion 14 are all hermetically fitted in the inner space 8 of the housing 7 (not visible in fig. 1). The base plate 5 of the throttle system 1 is rigidly connected to the housing 7. The housing 7 is connected to the housing 11 of the device via an intermediate part 10 so that the device is rigidly suspended at a desired height, for example in a mine shaft, and oriented in line with the direction of flow. The arrangement further comprises an air guide 12 arranged on one side of the throttle system 1 comprising the throttle (or choke) part 2 and on the opposite side an air guide 13 for measurement in that direction.

In the embodiment shown, the balance axis 9 in the throttle system 1 coincides with the axis of symmetry of the throttle system 1 in the entire installation.

The detection signal output section 14, which is composed of a strain gauge pressure sensor, is connected to a recording unit, not shown in the drawings, which includes an amplifier, signal transmitter, display and possibly a signal processing section.

The device has the following functions:

the fluid, such as air, hits the throttling (or flow-resisting) part 2, the direction of the airflow changes as a result of the impact, the impulse of the flowing air also changes, and the impact of the airflow generates a force on the throttling (or flow-resisting) part 2, which is consistent with the flowing direction. One component of the force is parallel to the balance shaft 9 and transfers a certain amount of torque to the throttle (or choke) system 1. The remaining partial forces do not cause disturbing deformations of the elastic support 3.

The leaf spring is elastically deformed by the action of the torque, and this deformation causes the detection signal output portion 14 to generate a corresponding output signal.

The output signal of the detection signal output section 14 is introduced into an amplifier of appropriate gain, which amplifies the signal to a desired degree. The signal may be displayed on any desired display, either analog or digital, or may be input to a recording device. The corresponding amplified signal may also be transmitted a great distance away for further data or signal processing. For example, the signals may be input to a remote control system and/or processed by a computer. The compensator is not shown in the figure.

Purely exemplary embodiments of the compensator not shown in the drawings are explained below:

in certain cases, the compensator may be a moving coil connected to the throttle (or choke) system 1. The moving coil also tries to rotate as a result of the torque to which the throttling (or flow-blocking) system 1 is subjected. By means of a suitable detector, for example an optical detector equipped with a light emitting diode, a phototransistor and a photoresistor, an output signal is generated which is a monotone continuous function of the angular displacement over the desired angular range. The output signal is then fed to a suitable high gain electronic amplifier, the output of which is of the current source type. If the output current is fed to the moving coil with the appropriate phase, the force to which the moving coil is subjected will cause the moving coil to move in the opposite direction to the torque to which the throttle (or choke) system 1 is subjected, which may cause the angular displacement of the moving coil to be so small that it can be considered as stationary in practice. In this case, the current or a voltage value proportional thereto can be expediently used as output signal and applied to the moving coil.

The main advantages of the solution proposed by the present invention are summarized as follows:

1. the device has better signal tracking ability to measure sensitivity than conventional devices for the same purpose.

2. The balance of the throttling (or flow-blocking) part makes the threshold value for driving or starting lower.

Claims (6)

1. A device for detecting the flow of a medium and measuring its flow rate, the device comprising a stationary throttling (or choking) system displaceable under the action of a fluid, a signal sensor for detecting the force exerted on the throttling (or choking) system, and a recording component for amplifying, transmitting, displaying and processing the signal of the sensor, wherein the device is characterized in that it comprises a housing (7) whose internal space (8) is completely or partially isolated from the fluid, a throttling (or choking) component (2) balancedly mounted on an axis (9) aligned with the flow direction, the throttling (or choking) component (2) being fixed to the throttling (or choking) system (1) and suitably mounted outside the internal space (8), and further comprising an elastic bracket (3) and a compensation component for completely or partially compensating for the force exerted on the throttling (or choking) component (2). 2. The device according to claim 1, characterized in that the throttling (or flow-blocking) component (2) is sealedly connected to the inner space (8). 3. A device according to claim 1 or 2, characterized in that the elastic bracket (3) is provided with a leaf spring between the throttling (or flow-blocking) component (2) and the bottom plate (5) of the throttling system (1), and the balancing shaft (9) is arranged on the plane of the leaf spring. 4. A device according to claim 1 or 2, characterised in that the compensating member is a spring mechanism or a weight mechanism or an electromagnetic device. 5. The device according to claim 1 or 2, characterized in that the detection sensor (14) and/or the compensation component are installed in the inner space (8) in an electrically insulated manner. 6. A device according to claim 1 or 2, characterised in that the plane of the throttling (or flow-blocking) element can be adjusted relative to the flow direction.