Acoustic emission sensor amplification circuit

Abstract

The utility model provides an acoustic emission sensor amplifying circuit which comprises a low-pass filter circuit, a charge amplifying circuit and an operational amplifying circuit, the charge amplifying circuit and the operational amplifying circuit are sequentially arranged at the output end of the low-pass filter circuit, a first pi filter circuit is arranged at the output end of the charge amplifying circuit, and a second pi filter circuit is arranged at the output end of the operational amplifying circuit. The acoustic emission sensor amplifying circuit further comprises an alternating current coupling circuit, and the alternating current coupling circuit comprises a first alternating current coupling capacitor and a second alternating current coupling capacitor which are arranged on one side of the output end of the charge amplifying circuit and one side of the output end of the operational amplifying circuit respectively. The secondary amplification circuit is arranged to amplify charges and signals, and the pi filter circuit is arranged to reduce bottom noise, so that detection requirements are met, weak charge signals output by the acoustic emission sensor can be effectively amplified, signal strength is enhanced, attenuation of the signals during transmission in a cable is reduced, and detection accuracy is improved. Therefore, the transmission distance and the transmission quality of the signal are greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of acoustic emission sensors, in particular to an acoustic emission sensor amplifier circuit. Background Art

[0002] Acoustic emission sensors are the sensing elements of the acoustic emission detection system. They are mainly used to detect the initiation and expansion of cracks at railway switches on high-speed railways, and play a very important role in the safe operation of high-speed railways.

[0003] Among the existing technologies, the acoustic emission sensors commonly used on high-speed railways have a center frequency of around 140kHz and are of the receiving type. They receive the vibration signal generated by a passing train, causing the piezoelectric ceramic to produce a piezoelectric effect and output a trace charge signal. By observing the changes in the signal, they can detect slight cracks in the rails, but they cannot determine the exact location of the cracks. The maximum transmission distance is about 10 meters. When the crack cross-section is greater than 50%, the sensor with a center frequency of 140kHz is no longer applicable.

[0004] Therefore, it is necessary to design an acoustic emission sensor with a center frequency of about 60kHz to detect larger cracks in the cross section. The sensors are used in pairs, one as the transmitting stage and the other as the receiving stage, so as to accurately locate the position of the cross section; the charge signal output by the acoustic emission sensor for detecting cracks at railway switches is very weak. Since the signal will attenuate during transmission in the cable, in order to improve the transmission distance and transmission quality of the signal, the charge of the acoustic emission sensor needs to be amplified. Utility Model Content

[0005] In view of the deficiencies in the prior art, the purpose of the utility model is to provide an acoustic emission sensor amplifier circuit, aiming to solve the technical problem of poor long-distance transmission quality of the acoustic emission sensor in the prior art.

[0006] In order to achieve the above-mentioned purpose, the utility model is realized through the following technical scheme: an acoustic emission sensor amplifier circuit, including a low-pass filter circuit, and a charge amplifier circuit and an operational amplifier circuit sequentially arranged at the output end of the low-pass filter circuit, the output end of the charge amplifier circuit is provided with a first π filter circuit, the output end of the operational amplifier circuit is provided with a second π filter circuit, the acoustic emission sensor amplifier circuit also includes an AC coupling circuit, and the AC coupling circuit includes a first AC coupling capacitor and a second AC coupling capacitor respectively arranged on one side of the output end of the charge amplifier circuit and the operational amplifier circuit.

[0007] Compared with the prior art, the beneficial effects of the utility model are as follows: by setting a low-pass filter circuit to filter out some peak signals, and setting a charge amplifier circuit to amplify the charge, since the front-end signal is low, the signal is amplified by setting an operational amplifier circuit, and the background noise is reduced by setting a π filter circuit to meet the detection requirements, and the weak charge signal output by the acoustic emission sensor can be effectively amplified, the signal strength is enhanced, and the attenuation of the signal during transmission in the cable is reduced, thereby greatly improving the transmission distance and transmission quality of the signal. At the same time, by setting an AC coupling circuit, the effective transmission of the signal between the circuits of each level is realized, and the DC signal is filtered out by the AC signal, thereby avoiding the signal interference of the DC bias introduced by the previous circuit, and ensuring the accuracy and integrity of the signal.

[0008] According to one aspect of the above technical solution, the low-pass filter circuit includes a first low-pass filter capacitor connected to the output end of the signal receiving end, and a second low-pass filter capacitor arranged between the charge amplifier circuit and the first AC coupling capacitor, and a first resistor is also arranged between the first low-pass filter capacitor and the signal receiving end.

[0009] According to one aspect of the above technical solution, the charge amplifier circuit includes a charge amplifier connected to the output end of the first low-pass filter capacitor, and a second resistor arranged at the output end of the charge amplifier.

[0010] According to one aspect of the above technical solution, the charge amplifier circuit further includes a bias resistor connected to the charge amplifier.

[0011] According to one aspect of the above technical solution, the charge amplifier circuit further includes a third resistor arranged at the input end of the charge amplifier.

[0012] According to one aspect of the above technical solution, the operational amplifier circuit includes an operational amplifier arranged at the output end of the first π filter circuit, and a fourth resistor, a fifth resistor and a first capacitor connected to the operational amplifier, and the output end of the operational amplifier is connected to the second AC coupling capacitor.

[0013] According to one aspect of the above technical solution, the first π filter circuit includes a second capacitor, a third capacitor and a sixth resistor arranged at the output end of the charge amplifier circuit, and the second π filter circuit includes a fourth capacitor, a fifth capacitor and a seventh resistor arranged at the output end of the operational amplifier circuit.

[0014] According to one aspect of the above technical solution, the acoustic emission sensor amplification circuit also includes a plurality of decoupling capacitors connected to a power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1This is the circuit diagram of the acoustic emission sensor amplifier circuit in an embodiment of the present utility model;

[0016] Description of main component symbols:

[0017] The first resistor 11, the second resistor 12, the third resistor 13, the first low-pass filter capacitor 21, the second low-pass filter capacitor 22, the charge amplifier 31, the bias resistor 32, the first AC coupling capacitor 41, the second AC coupling capacitor 42, the operational amplifier 61, the fourth resistor 62, the fifth resistor 63, the first capacitor 64, the sixth resistor 51, the second capacitor 52, the third capacitor 53, the seventh resistor 54, the fourth capacitor 55, the fifth capacitor 56;

[0018] The following specific embodiments will further illustrate the present utility model in conjunction with the above-mentioned drawings. Specific embodiments

[0019] For the convenience of understanding the present utility model, the present utility model will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present utility model are given in the drawings. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present utility model more thorough and comprehensive.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs. The terms used herein in the specification of the present utility model are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0022] Please refer to Figure 1, shown is a circuit diagram of an acoustic emission sensor amplifier circuit in an embodiment of the utility model. As shown in the figure, the amplifier circuit includes a low-pass filter circuit, and a charge amplifier circuit and an operational amplifier circuit sequentially arranged at the output end of the low-pass filter circuit. The output end of the charge amplifier circuit is provided with a first π filter circuit, and the output end of the operational amplifier circuit is provided with a second π filter circuit. The acoustic emission sensor amplifier circuit also includes an AC coupling circuit, and the AC coupling circuit includes a first AC coupling capacitor 41 and a second AC coupling capacitor 42 respectively arranged at one side of the output end of the charge amplifier circuit and the operational amplifier circuit.

[0023] Some peak signals are filtered out by setting a low-pass filter circuit, and a charge amplifier circuit is set to amplify the charge. Since the front-end signal is low, the signal is amplified by setting an operational amplifier circuit, and the background noise is reduced by setting a π filter circuit to meet the detection requirements. The weak charge signal output by the acoustic emission sensor can be effectively amplified, the signal strength is enhanced, and the attenuation of the signal during transmission in the cable is reduced, thereby greatly improving the transmission distance and transmission quality of the signal. At the same time, the AC coupling circuit is set to realize the effective transmission of the signal between the circuits at all levels, and the DC signal is filtered out by the AC signal, thereby avoiding the signal interference of the DC bias introduced by the previous circuit, and ensuring the accuracy and integrity of the signal.

[0024] Preferably, in this embodiment, the low-pass filter circuit includes a first low-pass filter capacitor 21 connected to the output end of the signal receiving end, and a second low-pass filter capacitor 22 provided between the charge amplifier circuit and the first AC coupling capacitor 41, and a first resistor 11 is further provided between the first low-pass filter capacitor 21 and the signal receiving end. After the signal is output from the receiving end, it passes through the low-pass filter circuit, which only allows low-frequency signals to pass through, and generates a large attenuation on high-frequency signals to filter out peak signals.

[0025] Furthermore, in this embodiment, the charge amplifier circuit includes a charge amplifier 31 connected to the output end of the first low-pass filter capacitor 21, and a second resistor 12 provided at the output end of the charge amplifier 31. The charge signal passes through the first resistor 11, and then is coupled to the second resistor 12 through the charge amplifier 31. The charge amount and the second resistor 12 form a proportional relationship, and the output voltage after the charge amplifier 31 is determined by the second resistor 12.

[0026] Preferably, in this embodiment, the charge amplifier circuit further includes a third resistor 13 provided at the input end of the charge amplifier 31. The third resistor 13 is provided on the NC pin. When the third resistor 13 is turned on, the amplifier circuit is a standard amplifier with charge amplification, and has a certain amplification effect on some signals that are not of standard charge amount.

[0027] For ease of understanding, the above-mentioned second resistor 12 is connected to the output terminal of the charge amplifier 31, and together with the charge amplifier 31, a feedback network is formed. The voltage output by the charge amplifier 31 is proportional to the current passing through the second resistor 12 (i.e., the amplified charge signal). Therefore, the resistance value of the second resistor 12 determines the amplification factor of the output voltage of the charge amplifier 31; the above-mentioned third resistor 13 is an optional resistor, which is set on the NC pin at the input terminal of the charge amplifier 31, that is, the "no connection" pin, and is used as an optional input in this design. When the third resistor 13 is connected, it changes the input impedance and feedback network of the charge amplifier 31, enabling the amplification circuit to process signals with non-standard charge amounts and amplify them to a certain extent, increasing the flexibility and adaptability of the circuit.

[0028] Preferably, in this embodiment, the above-mentioned charge amplification circuit further includes a bias resistor 32 connected to the charge amplifier 31. By setting the bias resistor 32, a stable bias current or voltage is provided for the charge amplifier 31 to ensure that the amplifier can operate stably in its linear region and reduce the drift caused by temperature changes or other factors.

[0029] Specifically, in this embodiment, the above-mentioned operational amplification circuit includes an operational amplifier 61 provided at the output terminal of the first π-filter circuit, and a fourth resistor 62, a fifth resistor 63, and a first capacitor 64 connected to the operational amplifier 61. The output terminal of the operational amplifier 61 is connected to the second AC coupling capacitor 42. The above-mentioned operational amplifier 61, fourth resistor 62, fifth resistor 63, and first capacitor 64 constitute a standard operational amplification circuit, and the above-mentioned first capacitor 64 is used to filter out spike signals.

[0030] Furthermore, in this embodiment, the above-mentioned first π-filter circuit includes a second capacitor 52, a third capacitor 53, and a sixth resistor 51 provided at the output terminal of the charge amplification circuit, and the second π-filter circuit includes a fourth capacitor 55, a fifth capacitor 56, and a seventh resistor 54 provided at the output terminal of the operational amplification circuit. The above-mentioned first π-filter circuit and second π-filter circuit are both used to remove the background noise to meet the requirement of the peak background noise of 5mv for the amplifier.

[0031] Preferably, in this embodiment, the acoustic emission sensor amplification circuit further includes a plurality of decoupling capacitors connected to the power supply. When components such as the operational amplifier 61 in the circuit are in the switching state, they will draw transient currents from the power supply, and these transient currents will generate voltage fluctuations on the power supply line, that is, power supply noise. The decoupling capacitors can provide a low-impedance current path, thereby quickly responding to these transient current demands, reducing the impact of power supply noise on other parts of the circuit, and improving the signal quality and detection accuracy.

[0032] In summary, the acoustic emission sensor amplification circuit in the above-mentioned embodiment of the utility model filters out some peak signals by setting a low-pass filter circuit, and sets a charge amplifier circuit to amplify the charge. Since the front-end signal is low, the signal is amplified by setting an operational amplifier 61, and the background noise is reduced by setting a π filter circuit to meet the detection requirements. It can effectively amplify the weak charge signal output by the acoustic emission sensor, enhance the signal strength, and reduce the attenuation of the signal during transmission in the cable, thereby greatly improving the transmission distance and transmission quality of the signal. At the same time, by setting an AC coupling circuit, the effective transmission of the signal between the various levels of circuits is realized, and the DC signal is filtered out by the AC signal, thereby avoiding the signal interference of the DC bias introduced by the previous circuit, and ensuring the accuracy and integrity of the signal.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model shall be subject to the attached claims.

Claims

1. An acoustic emission sensor amplifier circuit, characterized in that: It includes a low-pass filter circuit, and a charge amplifier circuit and an operational amplifier circuit which are sequentially arranged at the output end of the low-pass filter circuit, wherein the output end of the charge amplifier circuit is provided with a first π filter circuit, and the output end of the operational amplifier circuit is provided with a second π filter circuit. The acoustic emission sensor amplifier circuit also includes an AC coupling circuit, and the AC coupling circuit includes a first AC coupling capacitor and a second AC coupling capacitor which are respectively arranged at one side of the output end of the charge amplifier circuit and the operational amplifier circuit.

2. The acoustic emission sensor amplifier circuit according to claim 1, characterized in that: The low-pass filter circuit includes a first low-pass filter capacitor connected to the output end of the signal receiving end, and a second low-pass filter capacitor arranged between the charge amplifier circuit and the first AC coupling capacitor. A first resistor is also arranged between the first low-pass filter capacitor and the signal receiving end.

3. The acoustic emission sensor amplifier circuit according to claim 2, characterized in that: The charge amplifier circuit includes a charge amplifier connected to the output end of the first low-pass filter capacitor, and a second resistor arranged at the output end of the charge amplifier.

4. The acoustic emission sensor amplifier circuit according to claim 3, characterized in that: The charge amplifier circuit also includes a bias resistor connected to the charge amplifier.

5. The acoustic emission sensor amplifier circuit according to claim 3, characterized in that: The charge amplifier circuit further includes a third resistor arranged at an input end of the charge amplifier.

6. The acoustic emission sensor amplifier circuit according to claim 1, characterized in that: The operational amplifier circuit includes an operational amplifier arranged at the output end of the first π filter circuit, and a fourth resistor, a fifth resistor and a first capacitor connected to the operational amplifier. The output end of the operational amplifier is connected to the second AC coupling capacitor.

7. The acoustic emission sensor amplifier circuit according to claim 1, characterized in that: The first π filter circuit includes a second capacitor, a third capacitor and a sixth resistor arranged at the output end of the charge amplifier circuit, and the second π filter circuit includes a fourth capacitor, a fifth capacitor and a seventh resistor arranged at the output end of the operational amplifier circuit.

8. The acoustic emission sensor amplifier circuit according to claim 1, characterized in that: The acoustic emission sensor amplifying circuit also includes a plurality of decoupling capacitors connected to a power supply.

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