CS205355B1 - Device for velocity of flow and through-flow liquid quantity measurement - Google Patents

Description

Czechoslovakia SOCIALISTIC

(19)

INVENTORY OFFICE DISCOVERY DESCRIPTION OF EXPLORATION 20 5355 (11) (B1 TO COPYRIGHT CERTIFICATE - -: ----—--- '"(51) Int. Cl.3 G 01 P 5/10 (22) Registered 23 01 78 (21) (PV 436-78). (40) Posted on 29 08 80 (45) Published 30 03 84 (75)

Author of the invention MAYER DANIEL prof. CSc., Pilsen, (54) Flow rate and flow rate measurement device 1 2

BACKGROUND OF THE INVENTION The present invention relates to a device for measuring the flow rate and flow rate of an electrically conductive fluid when the total amount of fluid to be measured is limited. The need for this measurement can be found, for example, in urology, in the investigation of urinary dynamics, where the patient is determined to give a plot of urine quantity and time and urine flow rate.

So far, the flow rate has been measured. the speed of mo-or uses a device that is based on a miniature DC dynamometer. In this apparatus, a light disk is mounted on the shaft of the DC motor, on which the vanes are blades. The flow rate of the fluid to be measured is fed in the tangent direction to the blades of the rotating disk, thereby producing a braking torque. If the motor is powered from a stabilized voltage source, the braking torque is proportional to the power supply; thus, the registration meter can record the current flow to obtain the desired graph. The disadvantage of this measuring device is that, due to the moment of inertia of the dynamometer torque and the disc, considerable errors occur due to rapid changes in flow-rate of urine. However, from a diagnostic point of view, it is important that the measurement is accurate because for some urinary tract or central nervous system diseases, the urine flow rate is dependent on time. Other errors in the apparatus of this type arise from the braking torque caused, for example, by friction in bearings and the like, which can change uncontrollably. Another type of urinary flow measuring device bases its function on this substance: the measured urine stream is fed into a container that is closed and empties a tube from which the air from the container is fed at the inlet. A thermistor sensor is mounted in the tube to measure the rate of flow of leaking air. This measurement of the fluid flow rate is susceptible to sensitivity, but not very accurate and reliable, with variations in ambient temperature and air humidity as well as the fact that urine particles are entrained by particles of ambient air entering the urine, which then flows through the tube containing the thermistor. The above-mentioned disadvantages are eliminated by the device for measuring the flow rate and the flow rate of the fluid on the principle of the sensor's resistance to the height of the fluid provided with the vessel for the measured fluid in which the sensor connected to the registration unit according to the invention is located. The advantage is that the sensor located in the container is connected to the registration unit 205355 via a transducer whose output is connected to the input of the derivative member. Output terminals are formed by the preamble of the derivation member.

According to the invention, it is advantageous if the intermediate converter and the derivative member is an insert filter. The measured amount of fluid comes in a container in which the sensor is designed so that its electrical resistance decreases with the amount of fluid. The sensor consists of two resistive elements formed by a single layer of resistance non-insulated wire being wound uniformly on the insulating mandrel. . The two resistive elements are housed in a metal or insulating tube so as to be parallel and in close proximity, but not to contact each other. The sensor tube is positioned perpendicular to the bottom of the container, the resistive members are electrically interconnected at the bottom of the container, and are connected to the converter by their other ends. The fluid coming into the vessel also flows into the sensor and electrically connects both wound resistive conductors. If the resistance resistance cell is of the order of 102 or 103 ohms, the resistance of the electrolyte between the resistance cells is practically negligible. The fluid level increases, increasingly the length of the resistive elements, increasing the resistance in the circuit, increasing the current flow, and increasing the voltage at the inserted resistive resistance in the inverter. The dependence of this voltage over time indicates the time course of the fluid flow to be examined. However, a simpler but less sensitive sensor can be formed such that one resistive element is replaced by a conductor that can be a sensor protection tube. If the dependence between the measurand and the gauge deflection is to be linear, the inductive reactance of the reject cells must be negligible relative to their resistance and further that the inductive reactance of the circuit that supplies the resistive cells is negligible relative to its resistance, even at the highest fluid level, i.e., the resistive cells assigned. If the soldering of the resistive elements is DC, then these requirements do not apply, but the resistive resistance between the resistive elements and the electrolyte due to the gaseous products of the electrolysis in progress, adhering to the electrodes. These effects are essentially eliminated when the sensor is supplied with alternating voltage. Disturbing noises are generated in the sensor circuit, which are the result of the aforementioned polarization phenomena on the electrodes and the ripple level of the measured fluid in the mechanical shock of the measuring device. They can be suppressed by a filter. The final processing of the voltage signal is due to its temporal derivation, which can be done by a derivative member, for example an RC cell. Cardiographs can be used to apply the device in urology, and other channels can be used for simultaneous sensing of other events, such as intramuscular pressure, intraabdominal pressure, electromyogram anal sphincter, and the like.

The flow rate measuring device according to the invention has properties which are in many respects more advantageous compared to the properties of meters used up to now. Above all, there is a higher accuracy, stability of this precision and its easy controllability, high operational reliability and good dynamic properties even with rapid changes in velocity flow. The device meets all the requirements arising from the use of health care: all its parts can be cleaned, the handling is simple, the possibility of damage due to improper handling can be avoided, not burdened by the patient and is not associated with the risk for the patient or the operator.

The device according to the invention can be used to measure both the flow rate and the flow rate, if the registration unit is connected directly to the converter output? filter.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and its advantages are explained in more detail with reference to the accompanying drawings, in which: Fig. 1 shows a functional diagram of the device, Fig. 2 a simple connection of the converter and Fig. 3 one of a possible design of the sensor.

The device for measuring the flow rate and the flow rate according to FIG. 1 is formed by the container 2 with the sump 1 and the outlet 4. In the vessel 2 there is a transducer 3 assembled with two-resistance elements 13.

The sensor 3 is connected to a converter 5 which includes a stabilized voltage source and an output voltage rectifier. The output of the transducer 5 is connected via a low pass filter 6, the output of which is connected by a registration unit 8, for example a cardiograph driver.

The device works so that. The fluid whose flow rate is measured is fed to the sump 1 and deflated into the vessel 2. The resistance of the sensor 3 located in the vessel 2 depends on the height x of the fluid. Since the sensor 3 is at a distance from the container 2 providing access to the liquid resistive elements 13, the sensor 3 would not react until the liquid level reaches a certain height x0 touching the first threads of the resistive elements 13. This residual space can be reduced by appropriately arranging the tube 14 of the sensor 3 and can be completely eliminated when a quantity of liquid is introduced into the container 2 at the beginning of each measurement, so that the level thereof is at the height of x0. The magnitude of the voltage at the output of the converter 5 is proportional to the current passing through the resistive elements 13, is thus inversely proportional to their resistance and thus also to the height x of the level

Claims (3)

205355 DIY, that is, proportional to the amount of fluid introduced. The voltage at the output of the inverter 5 contains a disturbing noise, which is caused by the ripple caused by the rectification of this voltage. This sum is removed by the low pass filter6. The voltage at the output terminals of the filter 6 is thus proportional to the amount of liquid fed to the vessel 2. The graph of the dependence of this amount over time is obtained by connecting the output terminals 21, 21 'of the filter 6 to the registration unit 8, e.g. Both inverter 5 and filter G suppress some interference and increase measurement accuracy, but are not important to the basic meter function. If the lower measurement accuracy is also satisfactory, the converter 5 can be replaced by a simple DC circuit containing a power source and the voltage sensing resistor can be omitted from the filter. However, it is important to have a derivative 7 connected to the output terminals of the filter 6, which converts the voltages expressing the quantity of the flow rate. Its time course is registered, for example, by a recorder connected to the input terminals of the derivation element 7. The transducer 5, the filter 6, and the derivation member 7 are differentiated. A simple connection of the converter 5 is shown in Fig. 2. The transformer 10 fed by the stabilized source supplies current to the resistive cells 13 of the sensor 3 connected to the input terminals of the object. An apparatus for measuring the flow rate of a flow rate of a fluid on the principle of the sensor's resistance to the level of a fluid, provided with a vessel for the measured fluid, in which a sensor connected to a registration unit is located, characterized in that a sensor (3J is located in the container) with the registration unit via the Z 'to the converter 5. The current is proportional to the voltage at the resistor 9 which, after a two-way rectifier in the Gratz circuit, is applied to the output terminals of the converter. In Fig. 3 one of the possible design solutions of the sensor 3 is indicated. The essential part of the sensor 3 are its two resistive cells 13 located in the tube 14. At the end of the sensor 3 at the bottom of the groove, the position of the resistive elements 13 is defined by a yoke 15 with holes 1, The wires of the two resistive elements 13 are connected there At the shutter 11 of the container 2, a metal nozzle 17 is attached to the insulating core of each of the resistive elements 13, which in turn has contact with the resistive wire and the lead conductor. Both metal extensions 17 are housed in the insulator 1B. The tube 14 of the sensor 3 is screwed into the holder 18, which is fixed in the container cap 11. In the closure 11 of the container 2, air vents 12 are formed. Outside the container 2, the holder 18 is provided with a cap nut 19. Aeration holes 12 and the filling holes 20 in the tube 14 of the sensor 3 need to be sufficiently large so that the flow rate is not reduced by the high hydraulic resistors. of an inventive transducer (5), the output of which is coupled to the input of the derivative member (7), wherein output terminals (21, 21 ') are formed by the input of the derivative member. 2. Apparatus according to claim 1, characterized in that a filter (6) is inserted between the transducer (-5) and the derivate (7 J). 3 drawings I