Multi-channel ion current detection circuit for aero-engine pedestal

Abstract

The invention discloses a multi-channel ion current detection circuit for an aero-engine pedestal. The multi-channel ion current detection circuit comprises a signal control box and a dual-channel real-time detection circuit, in each channel of the real-time detection circuit, the multi-gear ion current display circuit is connected to an ion current detection loop of the signal control box, and the ion current of the ion current detection loop in the signal control box is monitored in real time; in the threshold value display circuit and the multi-gear ion current threshold selection circuit which are connected in series, voltage division is realized through divider resistors which are connected in series at the front ends, adjustable resistors are connected in series on all voltage division paths, and all the voltage division paths which are connected in parallel and the adjustable resistors in the voltage division paths are connected to an ion current threshold value adjusting circuit of the signal control box. The ion current threshold value of the current threshold value adjusting circuit is set by adjusting the resistance value of the adjustable resistor in each voltage dividing path, and the voltage display of each voltage dividing resistor is realized through a voltmeter V1 connected with each voltage dividing resistor, so that the ion current threshold value set in the corresponding voltage dividing path is reflected through the display of the voltmeter V1. According to the technical scheme, the problems that an existing ionic current detection method cannot detect data of ionic current in an afterburner of an engine in real time, and the flame signal threshold value is difficult to adjust in the engine test run process are solved.

Description

Technical Field

[0001] The present invention relates to the field of, but is not limited to, aeroengine flame signal detection technology, and in particular to a multi-channel ion current detection circuit for an aeroengine test bench. Background Art

[0002] At present, the detection of flame signals in the afterburner of aircraft engines mainly adopts the ion current detection method. During the engine bench test, the ion current detection method determines whether the size of the ion current generated by the combustion in the afterburner is higher than the set flame signal threshold value. If it is higher than the threshold value, it is determined that there is a fire signal, and if it is lower than the threshold value, it is determined that there is no fire signal.

[0003] The above-mentioned existing ion current detection method cannot detect the ion current data of the engine afterburner in real time. In addition, the flame signal threshold value is fixed during the product assembly process and cannot be adjusted during the engine test run. Summary of the invention

[0004] Purpose of the present invention: In order to solve the above-mentioned technical problems, the embodiment of the present invention provides a multi-channel ion current detection circuit for an aircraft engine test bench to solve the problems that the existing ion current detection method cannot detect the data of the ion current in the engine afterburner in real time, and it is difficult to adjust the flame signal threshold value during the engine test.

[0005] Technical solution of the present invention: An embodiment of the present invention provides a multi-channel ion current detection circuit for an aircraft engine test bench, comprising: a signal control box and a dual-channel real-time detection circuit;

[0006] Wherein, each channel of the real-time detection circuit comprises: a threshold value display circuit and a multi-level ion current threshold selection circuit connected in series, and an ion current display circuit connected in parallel with the above circuits;

[0007] The multi-level ion current display circuit is connected to the ion current detection circuit of the signal control box, and is used to monitor the ion current of the ion current detection circuit in the signal control box in real time;

[0008] In the series threshold value display circuit and the multi-speed ion current threshold selection circuit, voltage division is achieved through a voltage-dividing resistor connected in series at the front end, and an adjustable resistor is connected in series on each voltage-dividing path, and each voltage-dividing path connected in parallel and its internal adjustable resistor are connected to the ion current threshold value adjustment circuit of the signal control box, and the ion current threshold value of the current threshold value adjustment circuit is set by adjusting the resistance value of the adjustable resistor in each voltage-dividing path, and the voltage display of each voltage-dividing resistor is achieved through a voltmeter V1 connected to each voltage-dividing resistor, so that the display of the voltmeter V1 reflects the ion current threshold value set in the corresponding voltage-dividing path.

[0009] Optionally, in the multi-channel ion current detection circuit for an aircraft engine test bench as described above, the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit include:

[0010] A plurality of resistors are connected in series between the positive and negative electrodes of a DC power supply, and a voltmeter V1 is used to respectively collect the voltage value between each resistor and the negative line of the power supply, a switch is connected between each resistor and the voltmeter V1, and each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor, and is used to select and display the ion current threshold value of the signal control box through the closed state of the switch.

[0011] Optionally, in the multi-channel ion current detection circuit for an aircraft engine test bench as described above, it is characterized in that the threshold value display circuit and the multi-level ion current threshold selection circuit connected in series specifically include:

[0012] Resistors R1 to R7 are connected in series between the positive and negative electrodes of a DC power supply, the negative electrode of the DC power supply is connected to the negative electrode of a voltmeter V1, and the ends of the resistors R1 to R7 connected to the positive electrode of the power supply are respectively connected to the positive electrode of the voltmeter V1 through the first switch channel in the switch, and the second switch channel in each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor; specifically, when the two switch channels of one of the switches are placed in a closed state at the same time, the current threshold value of the current threshold value adjustment circuit in the signal control box is set to a preset ion current threshold value through the resistor connected to the second switch channel, and the voltmeter V1 is turned on through the first switch channel to display the current ion current threshold value.

[0013] Optionally, in the multi-channel ion current detection circuit for an aircraft engine test bench as described above, the second switch channel of each switch is connected to the current threshold value adjustment circuit of the signal control box through a fixed resistor and an adjustable resistor connected in series, and the setting of the ion current threshold value corresponding to each switch is achieved by adjusting the resistance value of the adjustable resistor.

[0014] Optionally, in the multi-channel ion current detection circuit for an aircraft engine test bench as described above,

[0015] The threshold value display circuit is configured as an isolation ammeter A1, and the positive and negative electrodes of the isolation ammeter A1 are connected to the ion current detection loop of the signal control box to measure the ion current in the ion current detection loop in real time.

[0016] Optionally, the multi-channel ion current detection circuit for an aircraft engine test bench as described above further includes: a power connector X1, a cable, and a power connector X2;

[0017] Wherein, the ion current display circuit is connected to the ion current detection circuit of the signal control box through the power connector X1, the cable, and the power connector X2;

[0018] In the series-connected threshold value display circuit and the multi-speed ion current threshold selection circuit, the two ends of the parallel multi-speed ion current threshold selection circuit formed by each switch and its rear-end resistor are connected to the ion current threshold value adjustment circuit of the signal control box through the power connector X1, the cable, and the power connector X2, so as to set the ion current threshold value of the current threshold value adjustment circuit by setting the resistance value of the rear-end resistor of each switch.

[0019] Optionally, in the multi-channel ion current detection circuit for an aircraft engine test bench as described above,

[0020] In the first channel of the real-time detection circuit, the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit are set to realize the selection of five-level ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically:

[0021] The voltage divider resistors include R1 to R7, where R3 to R7 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA respectively, where the resistance value of R1 is 487Ω, the resistance value of R2 is 10Ω, the resistance values ​​of R3 to R6 are all 0.5Ω, and the resistance value of R7 is 1Ω;

[0022] In the second channel of the real-time detection circuit, the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit are set to realize the selection of five-level ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically:

[0023] The voltage-dividing resistors include R18 to R24, among which R20 to R24 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA respectively. Among them, the resistance value of R18 is 487Ω, the resistance value of R19 is 10Ω, the resistance values ​​of R20 to R23 are all 0.5Ω, and the resistance value of R24 is 1Ω.

[0024] Optionally, the multi-channel ion current detection circuit for an aircraft engine test bench as described above further includes: a digital controller and a flame detector; the digital controller is connected to a signal control box, and the output end of the signal control box is connected to the positive and negative electrodes of the flame detector;

[0025] The signal control box is used to convert the 28VDC from the aircraft into the 115V / 3.4kHz bipolar square wave alternating current required for the operation between the positive pole of the flame detector and the negative pole of the flame detector;

[0026] The positive electrode and negative electrode of the flame detector extend into the engine combustion flame to detect the ions generated by the combustion products in the engine combustion chamber. Under the action of 115V / 3.4kHz AC voltage, a unidirectional ion current is formed and the feedback signal is transmitted to the signal control box.

[0027] The signal control box is also used to output a high-level voltage signal to the digital controller after signal processing when the ion current is greater than or equal to the set ion current threshold value; and to output a low-level voltage signal to the digital controller after signal processing when the ion current is less than the set ion current threshold value, so that the digital controller controls other afterburner control signals of the engine according to the detection results.

[0028] Beneficial effects of the present invention: A multi-channel ion current detection circuit for an aircraft engine test bench provided by an embodiment of the present invention adds a peripheral dual-channel real-time detection circuit on the basis of an existing ion flame signal detection circuit. The real-time detection circuit of each channel includes: a threshold value display circuit and a multi-level ion current threshold selection circuit connected in series, and an ion current display circuit connected in parallel with the above circuit; the circuit principle is as follows Figure 2 As shown, the real-time detection circuit is designed in a dual-channel form, consisting of two identical circuit structures; in one channel of the real-time detection circuit, in the series-connected threshold value display circuit and the multi-speed ion current threshold selection circuit, voltage division is achieved through a voltage-dividing resistor connected in series at the front end, and an adjustable resistor is connected in series on each voltage-dividing path, and each voltage-dividing path connected in parallel with its internal adjustable resistor is connected to the ion current threshold value adjustment circuit of the signal control box, the ion current threshold value of the current threshold value adjustment circuit is set by adjusting the resistance value of the adjustable resistor in each voltage-dividing path, and the voltage display of each voltage-dividing resistor is achieved through a voltmeter V1 connected to each voltage-dividing resistor, so that the display of the voltmeter V1 reflects the ion current threshold value set in the corresponding voltage-dividing path.

[0029] During the aircraft engine bench test, the multi-channel ion current detection circuit for the aircraft engine bench provided by the present invention is used. On the one hand, it is possible to realize the synchronous real-time detection of the multi-channel afterburner ion current; on the other hand, it is possible to realize the matching verification of different ion current threshold values ​​with the engine control system by adjusting the ion current threshold value online, thereby providing data support for the research on the ion current of the engine afterburner. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0031] Figure 1The present invention is a schematic diagram of the detection principle of the existing ion flame signal of an aircraft engine;

[0032] Figure 2 A schematic diagram of the circuit structure of a multi-channel ion current detection circuit for an aircraft engine test bench provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0034] The above background technology has already explained the ion current detection method used for the flame signal detection of the afterburner of an aircraft engine. Figure 1 The figure shows a schematic diagram of the detection principle of the existing ion flame signal of an aircraft engine; the circuit signal control box for ion flame signal detection, a digital controller, a positive pole of a flame detector and a negative pole of a flame detector are composed. The internal circuit of the signal control box includes an AC square wave power supply circuit, an ion current threshold setting circuit, an ion current detection circuit, an ion current signal processing circuit, etc. The signal control box provides an AC square wave circuit to the positive pole of the flame detector and the negative pole of the flame detector, and detects the ion current detected by the ion detector. When the ion current is greater than or equal to the internally set ion current threshold value, a high level signal (fire signal) is output to the digital controller; when the ion current is less than the internally set ion current threshold value, a low level signal (no fire signal) is output to the digital controller.

[0035] Above Figure 1 The detection method shown has the following problems: on the one hand, it cannot detect the data of the ion current of the engine afterburner in real time; on the other hand, the flame signal threshold value is fixed during the product assembly process and cannot be adjusted during the engine test run.

[0036] New requirements have been put forward in the research stage of aircraft engines. On the one hand, the optimal detection range of the ion flame detector needs to be verified, so the ion current intensity detected at different positions needs to be detected in real time. On the other hand, the optimal ion current threshold value needs to be set according to the ion current test data to improve the anti-interference ability of ion current detection. The existing test bench equipment cannot achieve the above functions.

[0037] In order to solve the above-mentioned problems and address new demands for aircraft engines, an embodiment of the present invention provides a multi-channel ion current detection circuit for an aircraft engine test bench. When an aircraft engine afterburner is arranged on the engine test bench, the multi-channel ion current detection circuit provided by the embodiment of the present invention can detect the ion current of the engine afterburner.

[0038] The present invention provides the following specific embodiments which can be combined with each other. The same or similar concepts or processes may not be described in detail in some embodiments.

[0039] Figure 2 The circuit structure diagram of a multi-channel ion current detection circuit for an aircraft engine test bench provided by an embodiment of the present invention. Figure 2 As shown, the main circuit structure of the multi-channel ion current detection circuit provided by the embodiment of the present invention includes: a signal control box and a dual-channel real-time detection circuit.

[0040] like Figure 2 As shown, in the embodiment of the present invention, each channel of the real-time detection circuit comprises: a threshold value display circuit and a multi-level ion current threshold selection circuit connected in series, and an ion current display circuit connected in parallel with the above circuits;

[0041] The multi-level ion current display circuit in the embodiment of the present invention is connected to the ion current detection circuit of the signal control box, and is used to monitor the ion current of the ion current detection circuit in the signal control box in real time.

[0042] In the series threshold value display circuit and the multi-speed ion current threshold selection circuit in the embodiment of the present invention, voltage division is achieved through a voltage-dividing resistor connected in series at the front end, and an adjustable resistor is connected in series on each voltage-dividing path, and each voltage-dividing path connected in parallel and its internal adjustable resistor are connected to the ion current threshold value adjustment circuit of the signal control box, and the ion current threshold value of the current threshold value adjustment circuit is set by adjusting the resistance value of the adjustable resistor in each voltage-dividing path, and the voltage display of each voltage-dividing resistor is achieved through a voltmeter V1 respectively connected to each voltage-dividing resistor, so that the display of the voltmeter V1 reflects the ion current threshold value set in the corresponding voltage-dividing path.

[0043] For the dual-channel real-time detection circuit in the embodiment of the present invention, in the real-time detection circuit of one channel, a current threshold value display circuit is composed of resistors R1~R7 and a voltmeter V1, and different resistors are connected to display different values ​​when a multi-way switch (for example, a double-pole double-throw switch) is used for selection; resistors R8~R17 form a 5-speed ion current threshold value selection circuit, which is connected to the ion current threshold value adjustment circuit 1 in the signal control box through the power connector X1, the cable, and the power connector X2; the ammeter A1 is connected to the ion current detection loop 1 of the signal control box through the power connector X1, the cable, and the power connector X2.

[0044] The circuit principle of the real-time detection circuit of another channel is the same as the above.

[0045] In one implementation of the embodiment of the present invention, the threshold value display circuit and the multi-level ion current threshold selection circuit connected in series include:

[0046] A plurality of resistors are connected in series between the positive and negative electrodes of a DC power supply, and a voltmeter V1 is used to respectively collect the voltage value between each resistor and the negative line of the power supply, a switch is connected between each resistor and the voltmeter V1, and each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor, and is used to select and display the ion current threshold value of the signal control box through the closed state of the switch.

[0047] In one embodiment of this implementation, Figure 2 As shown, the threshold value display circuit and the multi-level ion current threshold selection circuit connected in series specifically include:

[0048] Resistors R1 to R7 are connected in series between the positive and negative electrodes of a DC power supply, the negative electrode of the DC power supply is connected to the negative electrode of a voltmeter V1, and the ends of the resistors R1 to R7 connected to the positive electrode of the power supply are respectively connected to the positive electrode of the voltmeter V1 through the first switch channel in the switch, and the second switch channel in each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor; specifically, when the two switch channels of one of the switches are placed in a closed state at the same time, the current threshold value of the current threshold value adjustment circuit in the signal control box is set to a preset ion current threshold value through the resistor connected to the second switch channel, and the voltmeter V1 is turned on through the first switch channel to display the current ion current threshold value.

[0049] In a specific implementation, the second switch channel of each switch is connected to the current threshold value adjustment circuit of the signal control box through a fixed resistor and an adjustable resistor connected in series, and the setting of the ion current threshold value corresponding to each switch is achieved by adjusting the resistance value of the adjustable resistor.

[0050] In one implementation of the embodiment of the present invention, the threshold value display circuit is configured as an isolated ammeter A1, the positive and negative electrodes of the isolated ammeter A1 are connected to the ion current detection circuit of the signal control box to measure the ion current in the ion current detection circuit in real time.

[0051] In one implementation of the embodiment of the present invention, Figure 2 As shown, the multi-channel ion current detection circuit may further include: a power connector X1, a cable, and a power connector X2.

[0052] In this implementation, the ion current display circuit is connected to the ion current detection circuit of the signal control box through the power connector X1, the cable, and the power connector X2.

[0053] In this implementation, in the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit, the two ends of the parallel multi-level ion current threshold selection circuit formed by each switch and its rear-end resistor are connected to the ion current threshold value adjustment circuit of the signal control box through the power connector X1, the cable, and the power connector X2, so as to set the ion current threshold value of the current threshold value adjustment circuit by setting the resistance value of the rear-end resistor of each switch.

[0054] In one implementation of the embodiment of the present invention, in the first channel of the real-time detection circuit, a threshold value display circuit and a multi-level ion current threshold selection circuit are set in series to realize the selection of five levels of ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically:

[0055] The voltage-dividing resistors include R1 to R7, among which R3 to R7 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA, respectively. Among them, the resistance value of R1 is 487Ω, the resistance value of R2 is 10Ω, the resistance values ​​of R3 to R6 are all 0.5Ω, and the resistance value of R7 is 1Ω.

[0056] In this implementation, similar to the first channel described above, in the second channel of the real-time detection circuit, a threshold value display circuit and a multi-level ion current threshold selection circuit are set in series to achieve the selection of five levels of ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically:

[0057] The voltage-dividing resistors include R18 to R24, among which R20 to R24 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA respectively. Among them, the resistance value of R18 is 487Ω, the resistance value of R19 is 10Ω, the resistance values ​​of R20 to R23 are all 0.5Ω, and the resistance value of R24 is 1Ω.

[0058] In an implementation of the embodiment of the present invention, the multi-channel ion current detection circuit may further include: a digital controller and a flame detector;

[0059] In this implementation, the digital controller is connected to the signal control box, the output end of the signal control box is connected to the positive and negative poles of the flame detector, and the signal control box is used to convert the 28VDC from the aircraft into the 115V / 3.4kHz bipolar square wave AC voltage required for the flame detector to work between the positive and negative poles of the flame detector;

[0060] The positive electrode and negative electrode of the flame detector extend into the engine combustion flame to detect the ions generated by the combustion products in the engine combustion chamber. Under the action of 115V / 3.4kHz AC voltage, a unidirectional ion current is formed and the feedback signal is transmitted to the signal control box.

[0061] The signal control box is also used for, when the ion current is greater than or equal to the set ion current threshold value, the signal control box performs signal processing and outputs a high-level voltage signal (fire signal) to the digital controller; when the ion current is less than the set ion current threshold value, the signal control box performs signal processing and outputs a low-level voltage signal (no-fire signal) to the digital controller; so that the digital controller controls other afterburner control signals of the engine according to the detection results.

[0062] The multi-channel ion current detection circuit for an aircraft engine test bench provided by the present invention adds a peripheral dual-channel real-time detection circuit on the basis of the existing ion flame signal detection circuit. The real-time detection circuit of each channel includes: a threshold value display circuit and a multi-level ion current threshold selection circuit connected in series, and an ion current display circuit connected in parallel with the above circuits; the circuit principle is as follows Figure 2 As shown, the real-time detection circuit is designed in a dual-channel form, consisting of two identical circuit structures; in one channel of the real-time detection circuit, in the series-connected threshold value display circuit and the multi-speed ion current threshold selection circuit, voltage division is achieved through a voltage-dividing resistor connected in series at the front end, and an adjustable resistor is connected in series on each voltage-dividing path, and each voltage-dividing path connected in parallel with its internal adjustable resistor is connected to the ion current threshold value adjustment circuit of the signal control box, the ion current threshold value of the current threshold value adjustment circuit is set by adjusting the resistance value of the adjustable resistor in each voltage-dividing path, and the voltage display of each voltage-dividing resistor is achieved through a voltmeter V1 connected to each voltage-dividing resistor, so that the display of the voltmeter V1 reflects the ion current threshold value set in the corresponding voltage-dividing path.

[0063] During the aircraft engine bench test, the multi-channel ion current detection circuit for the aircraft engine bench provided by the present invention is used. On the one hand, it is possible to realize the synchronous real-time detection of the multi-channel afterburner ion current; on the other hand, it is possible to realize the matching verification of different ion current threshold values ​​with the engine control system by adjusting the ion current threshold value online, thereby providing data support for the research on the ion current of the engine afterburner.

[0064] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A multi-channel ion current detection circuit for an aircraft engine test bench, characterized in that: include: Signal control box and dual-channel real-time detection circuit; Wherein, each channel of the real-time detection circuit comprises: a threshold value display circuit and a multi-level ion current threshold selection circuit connected in series, and an ion current display circuit connected in parallel with the above circuits; The multi-level ion current display circuit is connected to the ion current detection circuit of the signal control box, and is used to monitor the ion current of the ion current detection circuit in the signal control box in real time; In the series threshold value display circuit and the multi-speed ion current threshold selection circuit, voltage division is achieved through a voltage-dividing resistor connected in series at the front end, and an adjustable resistor is connected in series on each voltage-dividing path, and each voltage-dividing path connected in parallel and its internal adjustable resistor are connected to the ion current threshold value adjustment circuit of the signal control box, and the ion current threshold value of the current threshold value adjustment circuit is set by adjusting the resistance value of the adjustable resistor in each voltage-dividing path, and the voltage display of each voltage-dividing resistor is achieved through a voltmeter V1 connected to each voltage-dividing resistor, so that the display of the voltmeter V1 reflects the ion current threshold value set in the corresponding voltage-dividing path.

2. The multi-channel ion current detection circuit for an aircraft engine test bench according to claim 1, characterized in that: The series-connected threshold value display circuit and multi-level ion current threshold selection circuit include: A plurality of resistors are connected in series between the positive and negative electrodes of a DC power supply, and a voltmeter V1 is used to respectively collect the voltage value between each resistor and the negative line of the power supply, a switch is connected between each resistor and the voltmeter V1, and each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor, and is used to select and display the ion current threshold value of the signal control box through the closed state of the switch.

3. The multi-channel ion current detection circuit for an aircraft engine test bench according to claim 2, characterized in that: The series-connected threshold value display circuit and multi-level ion current threshold selection circuit specifically include: Resistors R1 to R7 are connected in series between the positive and negative electrodes of a DC power supply, the negative electrode of the DC power supply is connected to the negative electrode of a voltmeter V1, and the ends of the resistors R1 to R7 connected to the positive electrode of the power supply are respectively connected to the positive electrode of the voltmeter V1 through the first switch channel in the switch, and the second switch channel in each switch is connected to the current threshold value adjustment circuit of the signal control box through a preset resistor; specifically, when the two switch channels of one of the switches are placed in a closed state at the same time, the current threshold value of the current threshold value adjustment circuit in the signal control box is set to a preset ion current threshold value through the resistor connected to the second switch channel, and the voltmeter V1 is turned on through the first switch channel to display the current ion current threshold value.

4. The multi-channel ion current detection circuit for an aircraft engine test bench according to claim 3, characterized in that: The second switch channel of each switch is connected to the current threshold value adjustment circuit of the signal control box through a fixed resistor and an adjustable resistor connected in series, and the setting of the ion current threshold value corresponding to each switch is achieved by adjusting the resistance value of the adjustable resistor.

5. The multi-channel ion current detection circuit for an aircraft engine test bench according to claim 1, characterized in that: The threshold value display circuit is configured as an isolation ammeter A1, and the positive and negative electrodes of the isolation ammeter A1 are connected to the ion current detection loop of the signal control box to measure the ion current in the ion current detection loop in real time.

6. The multi-channel ion current detection circuit for an aircraft engine test bench according to any one of claims 1 to 5, characterized in that: Also includes: Power connector X1, cable, power connector X2; Wherein, the ion current display circuit is connected to the ion current detection circuit of the signal control box through the power connector X1, the cable, and the power connector X2; In the series-connected threshold value display circuit and the multi-speed ion current threshold selection circuit, the two ends of the parallel multi-speed ion current threshold selection circuit formed by each switch and its rear-end resistor are connected to the ion current threshold value adjustment circuit of the signal control box through the power connector X1, the cable, and the power connector X2, so as to set the ion current threshold value of the current threshold value adjustment circuit by setting the resistance value of the rear-end resistor of each switch.

7. The multi-channel ion current detection circuit for an aircraft engine test bench according to any one of claims 1 to 5, characterized in that: In the first channel of the real-time detection circuit, the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit are set to realize the selection of five-level ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically: The voltage divider resistors include R1 to R7, where R3 to R7 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA respectively, where the resistance value of R1 is 487Ω, the resistance value of R2 is 10Ω, the resistance values ​​of R3 to R6 are all 0.5Ω, and the resistance value of R7 is 1Ω; In the second channel of the real-time detection circuit, the series-connected threshold value display circuit and the multi-level ion current threshold selection circuit are set to realize the selection of five-level ion current threshold values ​​of 10μA, 15μA, 20μA, 25μA, and 30μA. Specifically: The voltage-dividing resistors include R18 to R24, among which R20 to R24 are connected to the switch of the voltmeter V1, and are used to display 30μA, 25μA, 20μA, and 15μA respectively. Among them, the resistance value of R18 is 487Ω, the resistance value of R19 is 10Ω, the resistance values ​​of R20 to R23 are all 0.5Ω, and the resistance value of R24 is 1Ω.

8. The multi-channel ion current detection circuit for an aircraft engine test bench according to any one of claims 1 to 5, characterized in that: Also includes: Digital controllers and flame detectors; The digital controller is connected to a signal control box, and the output end of the signal control box is connected to the positive and negative electrodes of the flame detector; The signal control box is used to convert the 28VDC from the aircraft into the 115V / 3.4kHz bipolar square wave alternating current required for the operation between the positive pole of the flame detector and the negative pole of the flame detector; The positive electrode and negative electrode of the flame detector extend into the engine combustion flame to detect the ions generated by the combustion products in the engine combustion chamber. Under the action of 115V / 3.4kHz AC voltage, a unidirectional ion current is formed and the feedback signal is transmitted to the signal control box. The signal control box is also used to output a high-level voltage signal to the digital controller after signal processing when the ion current is greater than or equal to the set ion current threshold value; and to output a low-level voltage signal to the digital controller after signal processing when the ion current is less than the set ion current threshold value, so that the digital controller controls other afterburner control signals of the engine according to the detection results.

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