Ultrasonic liquid level measuring system and device

Abstract

The invention discloses an ultrasonic liquid level measurement system and device.The ultrasonic liquid level measurement system comprises a converter calibration circuit, a transducer calibration circuit, a liquid level measurement control circuit, a transducer, a first contact and a second contact, one end of the first contact is connected with the liquid level measurement control circuit, one end of the second contact is connected with the transducer, and the other end of the second contact is connected with the transducer. The converter calibration circuit excites an echo signal analog signal according to a multi-pulse driving signal of the liquid level measurement control circuit, the transducer calibration circuit carries out blind area calibration and sensitivity compensation based on the current blind area liquid level, when the converter is calibrated, the first contact and the converter calibration circuit are conducted, and the transducer calibration circuit is switched on. The liquid level measurement control circuit is connected with the converter calibration circuit through a first contact; when the transducer is calibrated, the second contact and the transducer calibration circuit are conducted, and the liquid level measurement control circuit is connected with the transducer calibration circuit through the second contact. The converter calibration circuit and the transducer calibration circuit are used for calibration, and the problems of liquid level measurement deviation and failure are solved.

Description

Technical Field

[0001] The present application relates to the field of liquid measurement technology, and in particular, to an ultrasonic liquid level measurement system and device. Background Art

[0002] With the development of electronic technology, ultrasonic measurement has the characteristics of high measurement accuracy and no pressure loss on the measured fluid. It is widely used in industry and metering instruments. Its measurement principle mostly uses the time difference method for measurement. Ultrasonic liquid level measurement uses a transducer to send and receive ultrasonic waves, and uses the propagation speed of ultrasonic waves in the liquid to measure the liquid level.

[0003] However, in actual use, due to reasons such as the offset of the converter and the aging of the transducer, the liquid level measurement result of the liquid level measurement module may be offset, the blind area may become larger, and the sensitivity may be reduced, resulting in measurement deviation or failure. Summary of the invention

[0004] The purpose of the present application is to provide an ultrasonic liquid level measurement system and device to solve the problems of aging and deviation of liquid level measurement results in the existing ultrasonic liquid level measurement. In order to solve the above problems, the present application adopts the following technical solutions: The first aspect of the present application provides an ultrasonic liquid level measurement system, comprising: a converter calibration circuit, a transducer calibration circuit, a liquid level measurement control circuit, a transducer, a first contact and a second contact, wherein one end of the first contact is connected to the liquid level measurement control circuit, and one end of the second contact is connected to the transducer, the converter calibration circuit is used to excite an echo signal simulation signal according to a multi-pulse drive signal of the liquid level measurement control circuit to simulate an echo signal with a fixed transit time, and the transducer calibration circuit is used to perform blind spot calibration and sensitivity compensation based on a current blind spot liquid level, wherein when performing liquid level measurement, one end of the first contact and one end of the second contact are connected, and the liquid level measurement control circuit is connected to the transducer; when performing converter calibration, one end of the first contact and the converter calibration circuit are connected, and the liquid level measurement control circuit is connected to the converter calibration circuit through the first contact; when performing transducer calibration, one end of the second contact and the transducer calibration circuit are connected, and the liquid level measurement control circuit is connected to the transducer calibration circuit through the second contact. Furthermore, the converter calibration circuit includes an AND gate, a first trigger, a second trigger and an ultrasonic signal source, the output end of the second trigger and the ultrasonic signal source are both connected to the input end of the AND gate, the input end of the first trigger is connected to the signal input end, and the output end of the first trigger is connected to the input end of the second trigger.

[0005] Further, the converter calibration circuit includes a first RC circuit, one end of the first RC circuit is connected to the output end of the AND gate, and one end of the first RC circuit is connected to the signal output end.

[0006] Furthermore, the converter calibration circuit includes a first delay circuit and a second RC circuit, the first delay circuit is respectively connected to the two pins of the first contact and the first trigger, one end of the first delay circuit is connected to electricity, the other end of the first delay circuit is grounded, and the second RC circuit is respectively connected to the signal input end and the first trigger.

[0007] Furthermore, the converter calibration circuit includes a diode, and two ends of the diode are respectively connected to the second RC circuit and the signal input end.

[0008] Furthermore, the converter calibration circuit includes a second delay circuit, which is respectively connected to two pins of the second trigger, one end of the second delay circuit is connected to electricity, and the other end of the second delay circuit is grounded.

[0009] Furthermore, the ultrasonic liquid level satisfies the following relationship: L = K2 * K1 * X1 + b2; Wherein, L is the actual liquid level of the measured liquid, K1 is the calibration coefficient of the converter, K2 is the calibration coefficient of the transducer, X1 is the measured delay time, and b2 is the liquid level offset.

[0010] Furthermore, the working blind area of ​​the transducer satisfies the following relationship: hmin =β*d 2 / 4λ; Wherein, hmin is the working blind area of ​​the transducer, λ is the wavelength of the transducer, d is the diameter of the transducer, and β is the calibration coefficient of the transducer.

[0011] Furthermore, the sensitivity of the transducer satisfies the following relationship: Ar = Ar max * G *α; Among them, Ar is the signal amplitude, Ar max is the peak-to-peak value of the transducer output signal, G is the signal amplification factor, and α is the signal sensitivity calibration coefficient.

[0012] The present application also provides an ultrasonic liquid level measuring device, which includes any of the ultrasonic liquid level measuring systems described above.

[0013] Compared with the prior art, the beneficial effect of the present application is that by using the converter calibration circuit and the transducer calibration circuit in coordination, the measurement deviation caused by factors such as converter and transducer aging can be effectively eliminated, and the deviation of the converter and transducer can be automatically calibrated, thereby improving the accuracy of liquid level measurement; at the same time, the blind area of ​​the liquid level measurement module can be automatically calibrated to compensate for the sensitivity of the transducer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the system diagram of ultrasonic liquid level measurement system; Figure 2 Schematic diagram of the converter calibration circuit; Figure 3 Circuit diagram for converter calibration circuit; Figure 4 a schematic diagram for generating echoes for the converter calibration circuit; and Figure 5 Schematic diagram of liquid level measurement using an ultrasonic liquid level measurement system. DETAILED DESCRIPTION

[0015] The specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0016] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0017] It should be understood that the orientation or position relationship is based on the orientation or position relationship shown in the drawings. These orientation terms are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application.

[0018] Figure 1 2 is the system diagram of the ultrasonic level measurement system, 3 is the schematic diagram of the converter calibration circuit, Figure 3 The circuit diagram for the converter calibration circuit is shown below. Figure 4 Schematic diagram of the echo generation for the converter calibration circuit, Figure 5 This is a schematic diagram of the ultrasonic liquid level measurement system for liquid level measurement. Figures 1 to 5As shown, an embodiment of the present application provides an ultrasonic liquid level measurement system, including: a converter calibration circuit 100, a transducer calibration circuit 200, a liquid level measurement control circuit 300, a transducer 400, a first contact J1 and a second contact J2, one end of the first contact J1 is connected to the liquid level measurement control circuit 300, one end of the second contact J2 is connected to the transducer 400, the converter calibration circuit 100 is used to excite the echo signal simulation signal according to the multi-pulse drive signal of the liquid level measurement control circuit 300 to simulate the echo signal with a fixed transit time, and the transducer calibration circuit 200 is used to perform blind spot calibration based on the current blind spot liquid level. Calibration and sensitivity compensation, wherein, when liquid level measurement is performed, one end of the first contact J1 and one end of the second contact J2 are conducted, and the liquid level measurement control circuit 300 is connected to the transducer 400; when the converter is calibrated, one end of the first contact J1 and the converter calibration circuit 200 are conducted, and the liquid level measurement control circuit 300 is connected to the converter calibration circuit 200 through the first contact J1; when the transducer is calibrated, one end of the second contact J2 and the transducer calibration circuit 200 are conducted, and the liquid level measurement control circuit 300 is connected to the transducer calibration circuit 200 through the second contact J2. Specifically, the converter calibration circuit 100 generates a multi-pulse drive signal, and generates an analog echo signal according to the multi-pulse drive signal, and the transit time of the analog echo signal is set to a fixed value to simulate a real echo signal. The transducer calibration circuit 200 includes a blind spot calibration module and a sensitivity compensation module, and the blind spot calibration module is calibrated according to the current blind spot liquid level to eliminate the measurement deviation caused by the blind spot. The sensitivity compensation module performs sensitivity compensation according to the aging degree of the transducer to improve the accuracy of the measurement. The liquid level measurement control circuit 300 is responsible for controlling the operation of the entire liquid level measurement system, processing the signal from the transducer, and controlling the operation of the converter calibration circuit 100 and the transducer calibration circuit 200. The first contact J1 and the second contact J2: These two contacts are used to connect the liquid level measurement control circuit 300, the converter calibration circuit 100 and the transducer calibration circuit 200. When the liquid level is measured, one end of the first contact J1 and the second contact J2 is turned on, and the liquid level measurement control circuit 300 is connected to the transducer 400. When the converter is calibrated, one end of the first contact J1 is connected to the converter calibration circuit 100, and the liquid level measurement control circuit 300 is connected to the converter calibration circuit 100 through the first contact J1. When the transducer is calibrated, one end of the second contact J2 is connected to the transducer calibration circuit 200, and the liquid level measurement control circuit 300 is connected to the transducer calibration circuit 200 through the second contact J2.

[0019] It should be noted that by using the converter calibration circuit and the transducer calibration circuit in conjunction, the measurement deviation caused by factors such as converter and transducer aging can be effectively eliminated, and the deviation of the converter and transducer can be automatically calibrated, thereby improving the accuracy of liquid level measurement; at the same time, the blind area of ​​the liquid level measurement module can be automatically calibrated to compensate for the sensitivity of the transducer.

[0020] In some embodiments, the converter calibration circuit 100 includes an AND gate 101, a first trigger 102, a second trigger 103 and an ultrasonic signal source 104, the output end of the second trigger J2 and the ultrasonic signal source 104 are connected to the input end of the AND gate 101, the input end of the first trigger J1 is connected to the signal input end, and the output end of the first trigger 102 is connected to the input end of the second trigger 103.

[0021] Specifically, the AND gate 101 receives the output signal of the second trigger 103 and the signal of the ultrasonic signal source 104, and performs a logical AND operation on the two signals. For example, when both input signals are at a high level, the output signal of the AND gate is at a high level, otherwise it is at a low level. The first trigger 102 receives the signal at the signal input end (ultrasonic transmission signal Pul_1), and the second trigger 103 receives the output signal of the first trigger 102, converting it into an analog echo signal, and the transit time of the analog echo signal is set to a fixed value to simulate a real echo signal. The ultrasonic signal source 104 generates an ultrasonic signal. The frequency and intensity of the ultrasonic signal can be adjusted as needed.

[0022] For example, the trigger signal (Pul_1) is input to the first trigger 102, the first trigger 102 outputs the echo delay timing, the second trigger 103 outputs the echo pulse width timing, and after the echo pulse width timing and the signal of the ultrasonic signal source 104 pass through the AND gate 101, the echo timing is output.

[0023] In some embodiments, the converter calibration circuit 100 includes a first RC circuit 105 , one end of the first RC circuit 105 is connected to the output end of the AND gate 101 , and one end of the first RC circuit 105 is connected to the signal output end.

[0024] Specifically, the first RC circuit 105 includes resistors R5 and R6 and capacitors C4 and C5. The first RC circuit 105 performs filtering and noise reduction, wherein one end of the first RC circuit 105 is connected to the output end of the AND gate 101, and the other end is connected to the signal output end Vout. The AND gate 101 is used to receive the output signal of the second trigger 103 and the signal of the ultrasonic signal source 104, and perform a logical AND operation on the two signals. For example, when both input signals are at a high level, the output signal of the AND gate is at a high level, otherwise it is at a low level.

[0025] In some embodiments, the converter calibration circuit includes a first delay circuit 106 and a second RC circuit 107, the first delay circuit 106 is respectively connected to the first contact J1 and the two pins of the first trigger 102, one end of the first delay circuit 106 is powered, the other end of the first delay circuit 106 is grounded, and the second RC circuit 107 is respectively connected to the signal input end and the first trigger 102.

[0026] Specifically, the first delay circuit 106 is used to generate a delay signal to control the operation of the first trigger 102, wherein the first delay circuit 106 is respectively connected to the first contact J1 and two pins of the first trigger 102, one end of which is connected to electricity and the other end is grounded. The first trigger 102 receives a signal (Pul_1) at the signal input end. The second RC circuit 107 includes a resistor R3 and a capacitor C2, and the second RC circuit 107 is respectively connected to the signal input end and the first trigger 102.

[0027] In some embodiments, the converter calibration circuit 100 includes a diode 108 , and two ends of the diode 108 are respectively connected to the second RC circuit 107 and the signal input terminal.

[0028] Specifically, the diode 108 is used to protect the circuit from overvoltage shock and ensure the correct transmission of the signal, wherein the two ends of the diode 108 are respectively connected to the second RC circuit 107 and the signal input end, so that the signal (Pul_1) can only be transmitted from the signal input end through the second RC circuit 107 to the first trigger 102.

[0029] In some embodiments, the converter calibration circuit includes a second delay circuit 109, which is respectively connected to two pins of the second trigger 103, one end of the second delay circuit 109 is powered, and the other end of the second delay circuit 109 is grounded.

[0030] Specifically, the second delay circuit 109 is used to generate a delay signal to control the operation of the second trigger 103. The second delay circuit 109 is respectively connected to the two pins of the second trigger 103, one end is connected to electricity, and the other end is grounded. The second trigger 103 is used to receive the output signal of the second delay circuit 109. The converter calibration circuit 100 generates a delay signal for controlling the operation of the second trigger 103. The delay signal can ensure that the second trigger 103 is triggered at the correct time point, thereby generating a stable multi-pulse drive signal. Among them, by adjusting the resistor R4 and the capacitor value C3 of the second delay circuit 109, the delay time of the delay signal can be adjusted to adapt to different calibration requirements.

[0031] In order to better understand the converter calibration circuit 100, Figure 3The principle of converter calibration circuit 100 will be described.

[0032] The ultrasonic transmission signal Pul_1 is connected to the positive node of D1, the negative node of D1 is connected to the upper end of R3 and C2, and the lower end of R3 and C2 is grounded. The upper end of R3 and C2 is connected to the 2-pin input end of trigger 1, the 7-pin of trigger 1 (first trigger 102) is connected to the delay resistor R1 and the delay capacitor C1, the other end of the delay resistor R1 is connected to the power supply, one end of the delay capacitor C1 is grounded, and the 5-pin output of trigger 1 (first trigger 102) is connected to the 2-pin input end of trigger 2. The 7-pin of trigger 2 (second trigger 103) is connected to the delay resistor R4 and the delay capacitor C3, the other end of the delay resistor R4 is connected to the power supply, one end of the delay capacitor C3 is grounded, and the 5-pin output of trigger 2 (second trigger 103) is connected to the 2-pin input end of the logic AND gate (AND gate 101). The other input end of the 1-pin of the logic AND gate (AND gate 101) is connected to the ultrasonic signal source, the output of the 4-pin of the logic AND gate is connected to the upper end of the capacitor C4, the other end of the capacitor C4 is connected to R5, the other end of R5 is connected to the parallel connection of C5 and R6, the other ends of C5 and R6 are grounded, and the upper end node of C5 and R6 outputs the simulated ultrasonic echo signal containing the transit delay. The converter calibration circuit 100 generates a standard echo signal with fixed echo time, width and amplitude through the ultrasonic transmission timing, and inputs it to the input end of the ultrasonic amplifier circuit, thereby generating a fixed transit time calibration signal without the influence of the transducer.

[0033] In some embodiments, the ultrasonic liquid level satisfies the following relationship: L = K2 * K1 * X1 + b2; Wherein, L is the actual liquid level of the measured liquid, K1 is the calibration coefficient of the converter, K2 is the calibration coefficient of the transducer, X1 is the measured delay time, and b2 is the liquid level offset.

[0034] Specifically, according to the ultrasonic liquid level formula L = K * Lx + B, L is the actual liquid level, K is the calibration coefficient, Lx is the module return liquid level, and B is the actual blind area liquid level. In actual use, the deviation of the entire module includes the converter deviation and the transducer deviation. The converter deviation is expressed by Y1 = K1 * X1 + b1, where Y1 is the calibrated delay time, K1 is the converter calibration coefficient, X1 is the measured delay time, and b1 is the offset.

[0035] The transducer deviation is expressed as Y2 = K2 * X2 + b2, where Y2 is the calibrated liquid level time, K2 is the transducer calibration coefficient, X2 is the measured liquid level time, and b1 is the liquid level offset. In actual calibration, both the converter calibration and the transducer calibration are selected at the blind spot. For example, the blind spot hmin is 2mm (see Figure 4 and Figure 5), the highest liquid level H is 60mm, assuming that the simulated delay time of the converter calibration is 2uS and 60uS respectively. Since b1 = 0 in the blind spot, we can get L2mm = K1 * X1, L60mm = K1 * X1 + (60 - 2), combined with the actual test value X1, we can get K1. X2 in the transducer calibration formula is quantified by the converter, so we can get L = K2 * K1 * X1 + b2. Because the structure has not changed, b2 is fixed. The calibration is carried out in the blind area, so the calibrated L = 2mm. Then K2 = (L2mm - b2) / (K1 * X1), the new K2 value can be obtained.

[0036] The converter calibration coefficient K1 can be directly written into the calculation formula for storage, but the actual operating principle of the transducer calibration coefficient K2 is to update the operating frequency of the transducer to match.

[0037] In some embodiments, the working blind area of ​​the transducer satisfies the following relationship: hmin =β*d 2 / 4λ; Wherein, hmin is the working blind area of ​​the transducer, λ is the wavelength of the transducer, d is the diameter of the transducer, and β is the calibration coefficient of the transducer.

[0038] Specifically, the working frequency matching of the transducer mainly utilizes the following principles: From the transducer principle, it can be known that hb =d 2 / 4λ, that is, liquid level height = square of transducer diameter ÷ 4 times wavelength. Assume that the blind area at the factory is hmin and the wavelength is λ. After the customer uses it, the blind area becomes h'min, the wavelength is λ', and the calibration coefficient is β. The corresponding calculation formula is h'min =d 2 / 4λ',hmin = β* h'min =β* d 2 / 4λ. The aging of the transducer in actual use will be reflected in the change of the characteristics of d. However, in actual calibration, d cannot be changed, but we can change the wavelength λ to correct the enlarged blind area. According to the wavelength calculation principle, λ=c / f, that is, wavelength=speed÷frequency. The propagation speed of ultrasound in water is 1482 meters / second. For example, if the factory frequency used is 4MHz, it can be known that λ=0.37mm. The new blind area after substitution is hmin = d 2 / (β* 4 * 0.37), assuming that the blind zone calibration coefficient β is 0.9, then λ' = 0.33mm, and the frequency f is about 4.4MHz. This proves that when f is adjusted, the problem of enlarged blind zone can be calibrated, so that the calibrated hmin = h'min.

[0039] In the actual circuit of transducer calibration, a single pulse driving circuit is used to complete the transducer blind zone calibration. This is because a single pulse has a lower blind zone, so that the blind zone offset information can be obtained in advance and the blind zone calibration can be performed in time.

[0040] According to the principle, the phenomenon caused by the decrease in transducer sensitivity is that the echo amplitude decreases, which can cause the measurement value to deviate or be lost. In this way, transducer sensitivity compensation is required to improve the stability of the module. The present application switches to the sensitivity detection circuit and the single pulse drive circuit through the second contact J2 to specifically calculate and implement.

[0041] In some embodiments, the sensitivity of the transducer satisfies the following relationship: Ar = Ar max * G *α; Among them, Ar is the signal amplitude, Ar max is the peak-to-peak value of the transducer output signal, G is the signal amplification factor, and α is the signal sensitivity calibration coefficient.

[0042] Specifically, since the single pulse driving circuit used is a quantitative ultrasonic transmission driving circuit, a quantitative transmission signal can be obtained. The sensitivity detection circuit can detect the amplitude of the echo and quantitatively analyze the signal strength through the echo amplitude. The combination of the two can quantify the sensitivity of the transducer.

[0043] For example, when the instrument leaves the factory, the amplitude of the output echo signal of the amplifier circuit is As, and the peak-to-peak value of the output signal of the transducer is As. max , the signal amplification factor is G. After the customer uses it, the output echo signal amplitude of the amplifier circuit is Ar, and the peak-to-peak value of the transducer output signal is Ar max The signal sensitivity calibration coefficient is α. Therefore, the factory sensitivity As = As max * G, sensitivity after customer use Ar = Ar max *G*α. When Ar max When the amplitude of decreases, we need to adjust the value of sensitivity calibration coefficient α to make As = Ar. Assume Ar max If it is reduced to 0.9 times of the factory setting, then G needs to be updated to 1 / 0.9 = 1.11 times of the original value to compensate for the reduced sensitivity of the transducer.

[0044] In order to better understand the ultrasonic liquid level measurement system of the embodiment of the present application, the various parts of the ultrasonic liquid level measurement system are described in detail below.

[0045] The ultrasonic liquid level measurement system can perform self-calibration liquid level measurement, thereby realizing the self-calibration function of ultrasonic measurement. The ultrasonic liquid level measurement system includes a converter calibration circuit 100 and a transducer calibration circuit 200, combined with a liquid level measurement control circuit 300 and a transducer 400, thereby realizing self-calibration liquid level measurement.

[0046] The converter calibration circuit 100 excites the echo signal simulation signal according to the multi-pulse driving signal of the liquid level measurement control circuit 300, and simulates the echo signal with a fixed transit time. The converter calibration circuit 100 consists of trigger 1 (first trigger 102), trigger 2 (second trigger 103), ultrasonic signal source 104 and logic AND gate (AND gate 101). The converter calibration circuit 100 generates a standard echo signal with fixed echo time, width and amplitude through the ultrasonic transmission timing, and inputs it to the input end of the ultrasonic amplifier circuit, thereby generating a fixed transit time calibration signal without transducer influence.

[0047] The principle of the converter calibration circuit 100 is as follows: the ultrasonic transmission signal Pul_1 is connected to the positive node of D1, the negative node of D1 is connected to the upper ends of R3 and C2, and the lower ends of R3 and C2 are grounded. The upper ends of R3 and C2 are connected to the 2-pin input end of trigger 1 (first trigger 102), the 7-pin of trigger 1 (first trigger 102) is connected to the delay resistor R1 and the delay capacitor C1, the other end of the delay resistor R1 is connected to the power supply, one end of the delay capacitor C1 is grounded, and the 5-pin output of trigger 1 is connected to the 2-pin input end of trigger 2 (second trigger 103). The 7-pin of trigger 2 (second trigger 103) is connected to the delay resistor R4 and the delay capacitor C3, the other end of the delay resistor R4 is connected to the power supply, one end of the delay capacitor C3 is grounded, and the 5-pin output of trigger 2 is connected to the 2-pin input end of the logic AND gate (AND gate 101). The other input end of the 1-pin of the logic AND gate (AND gate 101) is connected to the ultrasonic signal source, the 4-pin output of the logic AND gate is connected to the upper end of the capacitor C4, the other end of the capacitor C4 is connected to R5, the other end of R5 is connected to the parallel connection of C5 and R6, and the other ends of C5 and R6 are grounded. The upper end node of C5 and R6 outputs the analog ultrasonic echo signal containing the transit delay.

[0048] The transducer calibration circuit 200 is used to perform blind spot calibration and sensitivity compensation at the current blind spot liquid level. The blind spot calibration method is to use a single pulse to drive the transducer with a smaller blind spot to verify the current blind spot offset for calibration. Sensitivity compensation is to use a single pulse to drive the transducer, detect the amplitude of the echo signal to quantitatively analyze the transducer sensitivity, and combine the PGA gain adjustment circuit to compensate the gain.

[0049] When the circuit is in working mode, the liquid level measurement control circuit 300 is connected to the transducer 400 through the first contact J1 and the second contact J2 normally closed contacts to perform a conventional liquid level measurement function.

[0050] When the circuit is in the converter calibration mode, the first contact J1 is actuated to open the normally closed contact and close the normally open contact, so that the liquid level measurement control circuit 300 and the converter calibration circuit 100 are connected.

[0051] When the circuit is in the transducer blind zone calibration mode, the second contact J2 is actuated to disconnect the normally closed contact and close the normally open contact, so that the liquid level measurement control circuit 300 and the transducer 400 calibration circuit are connected, and the single pulse drive circuit of the transducer calibration circuit 200 is used to drive the transducer.

[0052] When the circuit is in the transducer sensitivity compensation mode, the second contact J2 is actuated to disconnect the normally closed contact and close the normally open contact, so that the liquid level measurement control circuit 300 and the transducer calibration circuit 200 are connected, the single pulse drive circuit of the transducer calibration circuit 200 is used to drive the transducer 400 and the peak gain detection circuit is used to detect the signal amplitude.

[0053] It should be noted that in the ultrasonic level measurement system of the embodiment of the present application, the driving frequency is adjusted to match the transducer, the echo amplification factor is adjusted to compensate for the sensitivity, a single pulse quantitative driving transducer is used, a sensitivity detection circuit is used to quantify the ultrasonic echo signal strength, and the ultrasonic blind area calculation formula hb = d is used. 2 / 4λ to derive and adjust the blind zone value, so as to automatically calibrate the deviation of the converter, automatically calibrate the blind zone of the liquid level measurement module, automatically compensate for the sensitivity of the transducer, and automatically match the frequency of the transducer.

[0054] The present application also provides an ultrasonic liquid level measuring device, which includes any of the ultrasonic liquid level measuring systems described above.

[0055] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the same. Although the present application has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present application.

Claims

1. An ultrasonic liquid level measurement system, characterized in that: include: A converter calibration circuit, a transducer calibration circuit, a liquid level measurement control circuit, a transducer, a first contact and a second contact, wherein one end of the first contact is connected to the liquid level measurement control circuit, and one end of the second contact is connected to the transducer, the converter calibration circuit is used to excite an echo signal simulation signal according to a multi-pulse driving signal of the liquid level measurement control circuit to simulate an echo signal with a fixed transit time, and the transducer calibration circuit is used to perform blind spot calibration and sensitivity compensation based on the current blind spot liquid level, wherein when performing liquid level measurement, one end of the first contact and one end of the second contact are connected, and the liquid level measurement control circuit is connected to the transducer; when performing converter calibration, one end of the first contact and the converter calibration circuit are connected, and the liquid level measurement control circuit is connected to the converter calibration circuit through the first contact; when performing transducer calibration, one end of the second contact and the transducer calibration circuit are connected, and the liquid level measurement control circuit is connected to the transducer calibration circuit through the second contact.

2. An ultrasonic liquid level measurement system according to claim 1, characterized in that: The converter calibration circuit includes an AND gate, a first trigger, a second trigger and an ultrasonic signal source, the output end of the second trigger and the ultrasonic signal source are both connected to the input end of the AND gate, the input end of the first trigger is connected to the signal input end, and the output end of the first trigger is connected to the input end of the second trigger.

3. An ultrasonic liquid level measurement system according to claim 2, characterized in that: The converter calibration circuit includes a first RC circuit, one end of the first RC circuit is connected to the output end of the AND gate, and one end of the first RC circuit is connected to the signal output end.

4. The ultrasonic liquid level measurement system according to claim 2, characterized in that: The converter calibration circuit includes a first delay circuit and a second RC circuit, the first delay circuit is respectively connected to the first contact and the two pins of the first trigger, one end of the first delay circuit is powered, the other end of the first delay circuit is grounded, and the second RC circuit is respectively connected to the signal input end and the first trigger.

5. An ultrasonic liquid level measurement system according to claim 4, characterized in that: The converter calibration circuit includes a diode, and two ends of the diode are respectively connected to the second RC circuit and the signal input end.

6. The ultrasonic liquid level measurement system according to claim 2, characterized in that: The converter calibration circuit includes a second delay circuit, which is respectively connected to two pins of the second trigger, one end of the second delay circuit is connected to electricity, and the other end of the second delay circuit is grounded.

7. An ultrasonic liquid level measurement system according to claim 2, characterized in that: The ultrasonic liquid level satisfies the following relationship: L = K2 * K1 * X1 + b2; Wherein, L is the actual liquid level of the measured liquid, K1 is the calibration coefficient of the converter, K2 is the calibration coefficient of the transducer, X1 is the measured delay time, and b2 is the liquid level offset.

8. An ultrasonic liquid level measurement system according to claim 7, characterized in that: The working blind area of ​​the transducer satisfies the following relationship: hmin =β*d 2 / 4 minutes; Wherein, hmin is the working blind area of ​​the transducer, λ is the wavelength of the transducer, d is the diameter of the transducer, and β is the calibration coefficient of the transducer.

9. The ultrasonic liquid level measurement system according to claim 2, characterized in that: The sensitivity of the transducer satisfies the following relationship: Ar = Ar max * G *α; Among them, Ar is the signal amplitude, Ar max is the peak-to-peak value of the transducer output signal, G is the signal amplification factor, and α is the signal sensitivity calibration coefficient.

10. An ultrasonic liquid level measuring device, characterized in that: The ultrasonic liquid level measuring device comprises the ultrasonic liquid level measuring system according to any one of claims 1-9.

Images