DE3237015A1 - MEASURING PROBE ARRANGEMENT FOR MEASURING AND CONTROLLING OR CONTROLLING A FLUID - Google Patents

Description

DESCRIPTION

The invention relates to sensor and control or regulating arrangements, and in particular measuring sensor and control or Control arrangements for use in fluid monitoring and control or regulation; in particular, the invention relates to a probe assembly for measuring and controlling a fluid.

During many different operations or processes is the monitoring and control or regulation of fluids essential. Such monitoring and control or regulation spans the area of industrial Processes or procedures up to medical processes or processes. The extracorporeal treatment of blood, as it is done, for example, in artificial kidney machines, requires accurate and immediate Monitoring the conditions of the blood. The conditions to be monitored include: B. the flow rate of blood and the dialysate. Other conditions that are monitored in such treatment of the blood are z. B. the blood level in a bladder eliminator.

It should be pointed out that the arrangement described here is preferred for extracorporeal treatment of the blood, however, this arrangement is also used in the monitoring of fluid flows or others Fluid flows can be used in industrial processes or operations.

In the prior art arrangements used for monitoring various functions of fluids used in the medical field,

such as for monitoring the flow rate or level of a fluid, e.g. B. of blood / sound energy is used. In these arrangements the sound energy is on one side of a pipe or cylinder sent and received on the other side. Sending through air and sending through fluid are different Characteristics, and as a result, the monitor or the monitoring device can determine when the level of the Fluids has reached a height where it begins to interfere with the sound transmission or the transmitted sound, or where its interference with the sound transmission or the transmitted sound ends.

Flow rates, on the other hand, are often measured using venturi arrangements in which Differences in pressure can be measured. The penetration of the current liquid is achieved through the use of membrane devices prevents the fluid, the flow of which is to be measured, from the measuring parts disconnect the instrument device. However, the prior art devices allow, in particular as for the accuracy in relation to the cost of the equipment, i.e. the accuracy per equipment cost, as well as as for the ability to distinguish between small measurement differences in general, something to be desired left over.

Since the measurement of the characteristics of a fluid is often decisive and can actually decide whether a patient lives or dies, it is extraordinary It is important to be able to obtain such characteristics as, for example, the blood flow rate and / or the level of blood in a bladder excretion tube are to be adequately measured. * ■

Accordingly, the invention seeks to provide a sensor assembly for use in measurements of fluid characteristics are made available, especially for those measurements in which it is important that extensive and / or expensive parts of the metering assembly that are subject to corrosion physically from the current fluid are separated, as well as a sensor arrangement in which the disadvantages indicated above are substantially reduced or are completely switched off.

According to the invention there is provided a sensor assembly for measuring and provided controlling a fluid comprising: ultrasonic signal transmitting means; an echo signal receiving Facility; and measuring means for measuring the time between the transmission of the ultrasonic signal and the Receiving the echo signal to determine the distance traveled by the signal.

According to a further feature of the invention, a device made available, which responds to the mentioned distance if this is outside a predetermined Area by changing the distance to bring it to a desired value, which is within the predetermined range.

Another feature of the invention is the use of the arrangement to maintain the level of blood in the a bubble eliminator within predetermined specified limits.

Yet another feature of the invention is the use of the output of the arrangement to operate a pump such that air is added to or withdrawn from the bubble elimination tube, so

that thereby the level of blood therein is increased or decreased.

Another feature of the invention is the use of the arrangement in connection with an extracorporeal blood treatment arrangement, such that the latter is notified when the blood in a tube has fallen below a predetermined minimum level and saline solution is therefore added
must be added to the blood to raise the level again; this supply of saline solution can be effected by the arrangement according to the invention.

Finally, there is another feature of the invention
in that the ultrasonic transmitting and receiving device is used to determine the position of a flow resistance body, float or the like in a vertical fluid-carrying pipe and thereby the flow rate of the fluid in the pipe is determined.

Finally, there is still another feature of the invention
in that a device for operating a pump in
Response to the mentioned flow measurements like this
that the flow is made available within
pre-determined specified limits held or

is preserved.

The operation and use of the arrangement according to the invention are described below with reference to the figures the drawing explained in more detail with reference to some preferred embodiments; show it:

Fig. 1 is a simplified block diagram showing a

electronic sensor and control or regulating circuit of an arrangement according to the invention
shows;

3237Q15

Fig. 2 is a block diagram showing a servo arrangement shows which is used to operate an air pump to give a desired one Maintaining level range within a bubble eliminator; and

Fig. 3 is a block diagram showing an arrangement with closed Loop shows those used to control the flow rate of a fluid is used by controlling or

is regulated, which is used to send fluid through a treatment arrangement, in particular a blood treatment arrangement.
15th

The basic sensor arrangement 11 is shown in FIG. It comprises a tube 12 in which a distance is to be measured. In the present exemplary representation this distance D extends from the bottom 13 of the pipe to the level of a liquid 14 in the pipe. It is a device for sending a signal, preferably a sonic or ultrasonic signal, into the liquid intended. In detail, according to the illustration, a transducer 16, for example a piezoelectric transducer, attached to the bottom 13 of the tube 12. The transducer 16 also receives any echo signal from the surface whose Distance is to be measured. In the present exemplary case, the distance to be measured is the distance from the surface 14, which is the "sonic or ultrasonic vibrations reflected.

The transmitting apparatus comprises a signal generator 18 for generating the output frequency signal which is in the form of Pulses is sent. A gate device 1.9 prevents the signal from being sent by the signal generator as long as

until the gate is opened. The gate 19 is connected to the signal generator 18 via a conductor 21. A driver amplifier 22 feeds the converter 16 with the signal passed by the gate 19.
5

A pulse rate oscillator 23 supplies a Opening signal for the gate circuit 19. In detail, the pulse rate oscillator 23 is responsive to a Start signal SS operated, due to actuation of a start switch on the control panel of the device is obtained. The start signal SS is transmitted over conductor 25 and operates the pulse rate oscillator The output signal of the pulse rate oscillator is fed via conductor 26 to a synchronizing monostable Multivibrator circuit 24 transmitted.

The output signal of the circuit 24 fulfills two functions, the first function of which is to initiate the operation of the ultrasonic frequency oscillator 18. In contact In response to the operation of the signal generator 18, a signal is fed to the gate 19 via the conductor 21. the The second function of the circuit 24 is to act as the receiver circuit to lock.

At the same time, the output signal on conductor 27, which has been output from the synchronous monostable multivibrator circuit 24, via the conductor 28 to a another monostable multivibrator circuit 29 transmitted. This circuit is a monostable serving as a transmitter port Multivibrator circuit which, in response to receipt of the signal appearing on line 28, is operated. The monostable multivibrator circuit 29 serving as a transmitting port sends a signal to the conductor 31, which opens the gate 19, and thereby ejLn becomes an ultrasonic frequency signal via conductor 32 to driver 22

guided. The amplified signal appearing on the conductor 33 at the output of the driver 22 controls the transducer 16 so that an ultrasonic signal is emitted into the fluid in the pipe 12.
'. ■

It is a device for measuring height or level the indicated at 14 in Fig. 1 surface of the fluid provided, which is responsive to the receipt of a Responds to echoes from surface 14 of the fluid at which the fluid has an interface the gaseous part of the contents of the tube 12 forms. In particular, there is a reinforcing device for reinforcing of the signal received by the transducer 16 is provided. As shown in Fig. 1, the transducer 16 is connected to a first and second amplifier stage 34 and 35, respectively, coupled via the conductor 36, which in turn is via the conductor is connected to the converter 16.

As shown, the amplifiers are blocked by means of a signal from a monostable multivibrator circuit 37 serving as a receiving gate. The monostable multivibrator circuit 37 serving for blocking and releasing the reception or as a reception gate is operated in response to a signal on the conductor 31, which is fed to the monostable multivibrator circuit 37 via the line 38. The output signal of the monostable multivibrator circuit 37 is connected to the first and second receiving amplifiers 34 and 35 via the conductor 39 and the conductors 41 and 42, respectively. It should be noted that the first stage amplifier 34 is shown having a variable feedback resistor 43 for controlling the gain. The amplifiers 34 and 35 are normally operated when the lock signal is not present. _v

Furthermore, a device for selecting the echo signals is provided, which is done in that, inter alia, the Frequency of the suspected echo determined by selective reception of signals with the transmitted ultrasonic frequency will. In detail, a filter arrangement 46 is connected to a mixer circuit 44, as shown schematically coupled to receive signals of the transmitted frequency. The output signal of the mixer circuit M becomes amplified by an amplifier 47. The amplifier 47 is a video amplifier or a broadband amplifier. That The output of the amplifier 47 is fed to a pulse ratio amplifier circuit 48 supplied, which is used to determine the ratio of the pulse to the total pulse length, this further ensures that the correct signal is detected. As a result, the Circuit 48 as a detector for the echo signal.

Further determinations are made to ensure that the correct echo signal is being received. in the In each case, a threshold value detector circuit 51 is provided at the output of the detector 48. It delivers a signal only in response to a signal fed to the detector which is above a certain threshold level lies. If the signal is above a certain or predetermined threshold level, then it will Output from the threshold detector circuit 51 to a pulse width discriminator circuit 52 to ensure that the echo has been received and not noise.

The output of the pulse width discriminator 52 is then used to operate a time interval circuit or counter circuit 53. The counter circuit 53 begins in response to the output signal from the monostable multivibrator circuit 24 and an output

signal on conductor 28 to count. The output signal on conductor 28 is passed through conductor 54 to the counter circuit 53 transferred. The output of the counter 53 is then by means of a display circuit 56 on a Reproduced visual display device. The output of counter 53 on conductor 54 can also be used for this purpose to operate switches and / or one or more circuits if desired. In this way is in response to an ultrasonic frequency signal, that has been sent by the transmitter 16 and an echo coming from a device in the liquid or from the Liquid surface 14 has been received, a determination or measurement based on how long it takes to receive an echo after the signal has been sent is executed or it is based on the transmitted ultrasonic frequency signal of the echo mentioned determines the time between the transmission of this ultrasonic frequency signal and the reception of the echo. The display circuit converts this measured or counter value into a distance value. The distance value is further desired al Is converted to a level value in units. This is done using the ultrasonic signal constant or permanent automatic liquid level monitoring.

A device for stopping the count value or the counting status of the counter 53 is also provided. In detail is responsive to the circuit's detection of an echo having the correct pulse width 48 the signal from the detector is amplified by an amplifier 49 and to the first and second amplifiers and 35 transmitted to the gain of this amplifier to decrease, whereby the reception of any further impulses is stopped. As a result, it comes into contact on the start signal and the sent from the converter

Dete signal to the fact that the counting process in response to the. Reception by detector 48 of a signal determined to be the echo is stopped. Consequently the count provides the time difference between the time at which the signal from the transducer and the time at which the echo traveling back to transducer 16 was received.

Figures 2 and 3 illustrate how the output signal on conductor 57 is used to determine either the level of the fluid in a bubble eliminator or the flow rate of the fluid in a artificial kidney device, as z. B. in the applicant's patent application filed on the same filing date with the title "Extracorporeal blood treatment device" are described to control or regulate.

In Fig. 2, 12 is a bubble detector or a bubble eliminator, and as shown, the transducer 16 is attached thereto. The converter 16 converts that Echo signal into an electrical signal and outputs it to the electronic device shown in FIG. 1 is. This electronic device is designated as circuit 61 in FIG. 2. The output of the circuit 61 on the conductor 57 activates the circuit 58 in such a way that it emits a signal proportional to the distance D. The output signal of the circuit 58 is applied via the conductor 63 to an input of a comparator circuit 62 .; The other input of the comparator 62 is the analog value of the "set" signal. The output signal of the Comparator is the difference between the signals present at the inputs. This difference output is input to a servo amplifier 66 via conductor 64. The output signal of the servo amplifier 66 is used to drive a pump motor 67, the

in turn, the rotor in a rotary hose air pump or a peristaltic rotary air pump that acts as a pump 68 is indicated, drives. The pump 68 is operated in such a direction that it takes air out of the pipe 12 withdraws, so that thereby part of the back pressure of the air is removed and the level of fluid 14 (e.g. blood) is allowed to rise. If now that Signal from circuit 58 indicates that the level is increasing is high, appropriate steps are taken to lower the level, e.g. B. consist in that the pump 68 is driven in the opposite direction, so 'that air is pushed into the tube 12 and in this way the level of the fluid 14 is lowered.

Fig. 3 shows an arrangement which is used to determine the flow rate of a fluid such as dialysate in an artificial kidney machine. The echo surface 71 is a surface on a flow resistance body or a weighted or, with a certain weight provided float 72. The weighted float 72 is by means of the flow of the Fluid through inlet tube 73, the conical Channel 74 and the outlet tube 76, which leads to the rotary or peristaltic blood pump 77 and to the peristaltic blood pump 77 leads, driven or receives a certain buoyancy from this fluid. In the peristaltic Pump 77 push rollers, such as rollers 78, fluid through the Pipe 76 when the pump 77 is driven by the pump motor 81.

In the arrangement of FIG. 3, the output of the converter 16 is coupled to the electrical circuit 79 which comprises a comparator and a servo amplifier. That Output signal of the servo amplifier, which is on the conductor

70 appears, is used to adjust the rate or speed of the pump motor so that the set one As a result, the assembly maintains the flow rate upright within a given area.

During the operation of the device, the fluid operating characteristics, such as the flow or the flow rate and / or the level with high accuracy, repeatability and reliability is measured by determining the time it takes to complete an echo to receive a transmitted signal. The respective distance is equal to the duration multiplied by the The speed of sound in the monitored liquid divided by two.

Of course, the invention is not limited to the illustrated and described embodiments, but it can be within the scope of the subject matter of the invention as specified in the claims, as well in the context of the general inventive concept, as can be seen from the entire documentation, in a variety of ways Modify and realize wise.

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Claims (10)

KRAUS & ■ WEISERT PATENT LAWYERS AND APPROVED REPRESENTATIVES BEFORE THE EUROPEAN PATENT OFFICE DR. WALTER KRAUS DIPLOM CHEMIST · DR.-ING. ANNEKÄTE WEISERT DIPLHNG. SPECIALIZATION CHEMICALS IRMGARDSTRASSE 15 · D-80OO MÜNCHEN 71 · TELEPHONE Ο8Θ / 79 7Ο77-7Θ 7O 78 · TELEX Ο5-212166 kpat d TELEGRAM KRAUSPATENT.,. ., Λ Case 3 4 70 JS / BR ELMAR MEDICAL SYSTEMS LTD. Haifa / Israel Sensor arrangement for measuring and controlling or regulating a fluid P AT ENTA Ν 'SPRÜCHE 1.) Sensor arrangement for measuring and controlling or regulating of a fluid, characterized in that it comprises: an ultrasonic signal transmitter (16, 18, 22-32); one Echo signal receiving means (16, 34-47); and a measuring device (24, 49, 53) for measuring the time between sending an ultrasonic signal and receiving it of the echo signal to determine the distance (D) traversed by the signal. 2. Sensor arrangement according to claim 1, characterized in that it comprises a device (62-68; 78-81), which responds if the difference or the time span is outside of a previous by changing the distance (D) to bring it to the desired value, which is within the predetermined range. 3. Sensor arrangement according to claim 1, characterized in that the signal or the ultrasound 1 signal to a surface (71) of a flow resistance body, float or the like. (72) sent and the echo is received from this surface (71), the flow resistance body, float or the like (72) is moved in the liquid as a function of the flow or the throughflow of the liquid. 4. measuring sensor arrangement according to claim 1, characterized characterized in that the measuring means (24, 48, 49, 53) for measuring the time interval between transmissions of the ultrasonic signal and the reception of the echo signal has a counter device (53), as well as one on the Send the ultrasonic signal to the responding device (24) to initiate the counting process of the counting device (53), and a device (48, 49) responsive to the receipt of the echo signal for ending the counting process of the Counting device (53), so that as a result the count value of the counter (53) is a measure of the signal traversed distance (D). 5. Sensor arrangement according to claim 4, dad u r c h characterized in that the device (48, 49) for ending the counting process of the counting device (53) a pulse quotient amplification device (48) for determining the characteristics or characteristics of the transmitted Signal for determining the fact that an actual echo signal has been received, and a device (49) which is responsive to the reception of an actual echo signal by the receiver circuit (34-47) blocks the reception of further echoes and thereby ends the counting process. 6. Sensor arrangement according to one of claims 1 to 5, d a d u r c h characterized in that the Ultrasonic signal transmission device (16, 18, 22-32) and the Echo signal receiving device (16, 34-47) a single Transducer (16) in response to electrical signals with ultrasonic frequency, which it as an input signal are supplied, sends an ultrasonic signal, and a device (16) responsive to the reception of ultrasonic signals responds by converting these ultrasonic pressure signals into electrical signals, the device (16) is preferably the aforementioned single transducer (16). 7. Sensor arrangement according to claim 1, 4, 5 or 6, characterized in that the ultrasonic signal transmission device (16, 18, 22-32) sends signals to a liquid surface (14) in a tube (12) at the interface between the liquid surface (14 ) and a gas surface, and that the echo that comes back from the interface or from the liquid surface (14) is received at the transducer (16), so that the distance (D) traversed by the signals is determined. 8. Sensor arrangement according to one of claims 1 to 1, characterized in that a device (62; 79) for comparing the determined distance (D) with a set distance is provided, as well as a device (66,67; 81) which on Addresses differences between the determined distance (D) and the set distance by activating a device ^ (68; 77), so that this the determined distance (D) on the -A- Brings the value of the set distance. 9. A sensor arrangement according to claim 8, characterized in that the device which is activated in order to make the determined distance (D) equal to the set distance, a pump device
(68; 77) for pumping air or other fluid to or from a pipe (12) or flow meter (74).
10 10. A sensor arrangement according to claim 9, characterized in that the pump device
(77) is used to change the flow rate of fluid, in particular of a liquid.