Electrically-driven air compression device synchronously working along with engine and working method of electrically-driven air compression device

Abstract

The electrically-driven air compression device synchronously working along with the engine comprises a power supply circuit, a power grid power supply is connected with the input end of the power supply circuit, the input end of a voltage sampling circuit and a driving circuit, and the output end of the power supply circuit is connected with a reference voltage circuit, a comparison and judgment circuit, a feedback processing circuit and an air pressure detection circuit. The output end of the reference voltage circuit and the output end of the voltage sampling circuit are connected with the input end of the comparison and discrimination circuit, the output end of the comparison and discrimination circuit and the output end of the air pressure detection circuit are connected with the input end of the feedback processing circuit, and the output end of the feedback processing circuit is connected with the input end of the air pressure detection circuit. The output end of the air pressure detection circuit is connected with the input end of the drive circuit, and the output end of the drive circuit is connected with the compressed air motor. The risk that when the engine does not work, the driving motor is still automatically controlled to work repeatedly, the electric energy of the vehicle-mounted storage battery is consumed, the power of the vehicle-mounted storage battery is insufficient, and engine starting is affected is avoided.

Description

Technical Field

[0001] The invention relates to an electric driven compressed air device which works synchronously with an engine and a working method thereof. Background Art

[0002] The compressed air device of special vehicles is generally powered by the engine, and the engine's power head drives the air pump through mechanical transmission to inflate the gas cylinder. This mechanical drive has three disadvantages: (a) It requires an additional engine power head and a set of special mechanical transmission devices, which takes up a lot of space and is too heavy; (b) Since the engine power needs to be transmitted to the compressed air device through mechanical transmission, the compressed air device cannot be flexibly arranged on the special vehicle, which is not conducive to improving the human-machine environment of the special vehicle; (c) Regardless of whether the gas cylinder is full of gas, as long as the engine is working, the engine's power head will drive the air pump through mechanical transmission, causing energy loss.

[0003] Due to the many defects of traditional mechanically driven compressed air devices, some special vehicles are equipped with electric-driven compressed air devices. When the electric-driven compressed air device detects that the gas cylinder pressure is lower than a certain threshold, it automatically controls the drive motor to drive the air pump to work and inflate the gas cylinder. When the gas cylinder pressure is higher than a certain threshold, it automatically stops inflating. However, when the engine is not working, the electric-driven compressed air device will still automatically control the drive motor to work repeatedly, consuming the power of the vehicle battery, causing the vehicle battery to run low, affecting the engine starting. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an electrically driven compressed air device which has a simple structure and reliable operation and works synchronously with an engine, and provides a working method thereof.

[0005] The technical solution of the present invention for solving the above technical problems is: an electrically driven compressed air device that works synchronously with an engine, comprising a power supply circuit, a voltage sampling circuit, a reference voltage circuit, a comparison and discrimination circuit, a feedback processing circuit, an air pressure detection circuit and a drive circuit, the grid power supply is connected to the input end of the power supply circuit, the input end of the voltage sampling circuit and the drive circuit, the output end of the power supply circuit is connected to the reference voltage, the comparison and discrimination circuit, the feedback processing circuit and the air pressure detection circuit, the output end of the reference voltage circuit and the output end of the voltage sampling circuit are both connected to the input end of the comparison and discrimination circuit, the output end of the comparison and discrimination circuit and the output end of the air pressure detection circuit are connected to the input end of the feedback processing circuit, the output end of the feedback processing circuit is connected to the input end of the air pressure detection circuit, the output end of the air pressure detection circuit is connected to the input end of the drive circuit, and the output end of the drive circuit is connected to the compressed air motor.

[0006] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the power supply circuit includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a power module, the power module model is LM7815, the grid power supply is connected to one end of the first capacitor, one end of the second capacitor, and the input end of the power module, the other end of the first capacitor and the other end of the second capacitor are grounded, the output end of the power module is connected to one end of the third capacitor and one end of the fourth capacitor, the other end of the third capacitor and the other end of the fourth capacitor are grounded.

[0007] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the voltage sampling circuit includes a first resistor, a second resistor, an adjustable resistor, a fifth capacitor, and a voltage-stabilizing diode, one end of the first resistor is connected to the grid power supply, the other end of the first resistor is connected to one end of the fifth capacitor and one end of the second resistor, the other end of the second resistor is connected to the cathode of the voltage-stabilizing diode, the cathode of the voltage-stabilizing diode is grounded after passing through the adjustable resistor, and the other end of the fifth capacitor and the anode of the voltage-stabilizing diode are grounded.

[0008] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the reference voltage circuit includes a sixth capacitor, a seventh capacitor and a reference voltage module, the reference voltage module model is REF102BP, one end of the sixth capacitor is connected to the V+ end of the reference voltage module and the output end of the power supply module, the other end of the sixth capacitor is grounded, the NR port of the reference voltage module is grounded after passing through the seventh capacitor, and the output end of the reference voltage module is connected to the comparison and discrimination circuit.

[0009] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the comparison and discrimination circuit includes a first comparator, a third resistor, and a fourth resistor, the non-inverting input terminal of the first comparator is connected to the other end of the first resistor, the inverting input terminal of the first comparator is connected to the output terminal of the reference voltage module, the output terminal of the first comparator is connected to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is connected to the output terminal of the power supply module, and the other end of the fourth resistor is connected to the feedback processing circuit.

[0010] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the feedback processing circuit includes a PNP transistor, an NPN transistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor, the base of the PNP transistor is connected to the other end of the fourth resistor, the emitter of the PNP transistor is connected to one end of the seventh resistor and the output end of the power module, the collector of the PNP transistor is connected to the collector of the NPN transistor, the other end of the seventh resistor, one end of the eighth resistor, and the inverting input end of the second comparator, the other end of the eighth resistor is grounded, the emitter of the NPN transistor is grounded after passing through the sixth resistor, the base of the NPN transistor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the output end of the air pressure detection circuit.

[0011] The above-mentioned electrically driven compressed air device working synchronously with the engine, the air pressure detection circuit includes a ninth resistor, a tenth resistor, an eleventh resistor, a pressure switch, a second comparator, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a third comparator, the pressure switch is installed in the gas cylinder, one end of the ninth resistor is connected to the output end of the power module, the other end of the ninth resistor is connected to one end of the tenth resistor, the in-phase input end of the second comparator, and one end of the eleventh resistor, the other end of the tenth resistor is grounded, the other end of the eleventh resistor is connected to the 10MPa end of the pressure switch, the 14.4MPa end of the pressure switch is connected to one end of the twelfth resistor, one end of the thirteenth resistor, and the in-phase input end of the third comparator, the other end of the twelfth resistor is connected to one end of the fourteenth resistor and the output end of the power module, the other end of the thirteenth resistor is grounded, the other end of the fourteenth resistor is connected to the inverting input end of the third comparator and one end of the fifteenth resistor, the other end of the fifteenth resistor is grounded, the output end of the third comparator and the output end of the second comparator are connected to the input end of the drive circuit.

[0012] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the driving circuit includes a sixteenth resistor, a seventeenth resistor, an eighth capacitor, a contactor, a diode, and a field effect transistor, one end of the sixteenth resistor is connected to the output end of the power module, the other end of the sixteenth resistor is connected to the output end of the second comparator, the output end of the third comparator, one end of the seventeenth resistor, one end of the eighth capacitor, and the gate of the field effect transistor, the other end of the seventeenth resistor, the other end of the eighth capacitor, and the source of the field effect transistor are grounded, the drain of the field effect transistor is connected to the grid power supply through the coil of the contactor, the diode is connected in parallel to the two ends of the coil of the contactor, the grid power supply is connected to the compressed air motor through the normally open contact of the contactor, and the compressed air motor is powered to drive the inflation pump to inflate the gas cylinder.

[0013] The above-mentioned electrically driven compressed air device that works synchronously with the engine, the contactor model is MZJ-200A, the diode model is 1N4007, the field effect tube model is IRF540, the pressure switch model is ZPM760, and the first comparator, the second comparator, and the third comparator model are all LM139.

[0014] A method for operating an electrically driven compressed air device that operates synchronously with an engine comprises the following steps: Step 1: Turn on the main power switch of the special vehicle to power on; Step 2: Determine whether the engine is working by detecting the grid voltage. If the detected grid voltage is less than +27V, it means that the engine is not working. Disconnect the compressed air device drive circuit, stop charging, and continue to cycle to detect the grid voltage; if the detected grid voltage is greater than or equal to +27V, it means that the engine is working, and proceed to the next step; Step 3: Detect the cylinder pressure. If the cylinder pressure is less than 10MPa, proceed to step 4; if the cylinder pressure is between 10MPa and 14.4MPa, proceed to step 5; if the cylinder pressure is greater than 14.4MPa, proceed to step 6; Step 4: Connect the drive circuit, the compressed air motor drives the air pump to rotate, inflate the gas cylinder, and then return to step 2; Step 5: The driving circuit maintains its original state, that is, if the driving circuit is originally in a disconnected state, the driving circuit continues to be disconnected; if the driving circuit is originally in a connected state, the driving circuit continues to be connected, and then returns to step 2; Step 6: Disconnect the drive circuit, stop inflation, and return to step 2.

[0015] The beneficial effects of the present invention are: 1. Compared with the prior art, the present invention has smaller volume, lighter weight, more flexible layout and less energy loss.

[0016] 2. Compared with the prior art, the present invention avoids the risk of automatically controlling the drive motor to work repeatedly when the engine is not working, consuming the electric energy of the vehicle battery, causing the vehicle battery to run low, and affecting the starting of the engine.

[0017] 3. In addition to taking electricity from the special vehicle, the present invention has no other electrical connection with the special vehicle. When the special vehicle is modified and upgraded, the electric-driven compressed air device that works synchronously with the engine can be replaced without changing the existing state of the special vehicle. The replacement is convenient and there is no matching risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a circuit diagram of an electrically driven compressed air device that works synchronously with an engine.

[0019] Figure 2 The present invention is a flow chart of the working method of the electrically driven compressed air device that works synchronously with the engine.

[0020] In the figure, 1 is a first capacitor, 2 is a second capacitor, 3 is a power module, 4 is a third capacitor, 5 is a fourth capacitor, 6 is a first resistor, 7 is a fifth capacitor, 8 is a second resistor, 9 is a voltage regulator diode, 10 is an adjustable resistor, 11 is a sixth capacitor, 12 is a seventh capacitor, 13 is a first comparator, 14 is a reference voltage module, 15 is a third resistor, 16 is a fourth resistor, 17 is a PNP transistor, 18 is an NPN transistor, 19 is a fifth resistor, and 20 is a sixth resistor , 21 is the seventh resistor, 22 is the eighth resistor, 23 is the ninth resistor, 24 is the tenth resistor, 25 is the eleventh resistor, 26 is the pressure switch, 27 is the second comparator, 28 is the sixteenth resistor, 29 is the twelfth resistor, 30 is the thirteenth resistor, 31 is the fourteenth resistor, 32 is the fifteenth resistor, 33 is the third comparator, 34 is the contactor, 35 is the compressed air motor, 36 is the diode, 37 is the field effect transistor, 38 is the seventeenth resistor, and 39 is the eighth capacitor. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, an electrically driven compressed air device that works synchronously with an engine includes a power supply circuit, a voltage sampling circuit, a reference voltage circuit, a comparison and discrimination circuit, a feedback processing circuit, an air pressure detection circuit, and a drive circuit. The grid power supply is connected to the input end of the power supply circuit, the input end of the voltage sampling circuit, and the drive circuit; the output end of the power supply circuit is connected to the reference voltage, the comparison and discrimination circuit, the feedback processing circuit, and the air pressure detection circuit; the output end of the reference voltage circuit and the output end of the voltage sampling circuit are both connected to the input end of the comparison and discrimination circuit; the output end of the comparison and discrimination circuit and the output end of the air pressure detection circuit are connected to the input end of the feedback processing circuit; the output end of the feedback processing circuit is connected to the input end of the air pressure detection circuit; the output end of the air pressure detection circuit is connected to the input end of the drive circuit; and the output end of the drive circuit is connected to the compressed air motor 35.

[0023] The power supply circuit includes a first capacitor 1, a second capacitor 2, a third capacitor 4, a fourth capacitor 5, and a power module 3. The power module 3 is LM7815. The grid power supply is connected to one end of the first capacitor 1, one end of the second capacitor 2, and an input end of the power module 3. The other end of the first capacitor 1 and the other end of the second capacitor 2 are grounded. The output end of the power module 3 is connected to one end of the third capacitor 4 and one end of the fourth capacitor 5. The other end of the third capacitor 4 and the other end of the fourth capacitor 5 are grounded.

[0024] The voltage sampling circuit includes a first resistor 6, a second resistor 8, an adjustable resistor 10, a fifth capacitor 7, and a voltage-stabilizing diode 9. One end of the first resistor 6 is connected to the power grid, the other end of the first resistor 6 is connected to one end of the fifth capacitor 7 and one end of the second resistor 8, the other end of the second resistor 8 is connected to the cathode of the voltage-stabilizing diode 9, the cathode of the voltage-stabilizing diode 9 is grounded after passing through the adjustable resistor 10, and the other end of the fifth capacitor 7 and the anode of the voltage-stabilizing diode 9 are grounded.

[0025] The reference voltage circuit includes a sixth capacitor 11, a seventh capacitor 12 and a reference voltage module 14. The reference voltage module 14 is of model REF102BP. One end of the sixth capacitor 11 is connected to the V+ end of the reference voltage module 14 and the output end of the power supply module 3. The other end of the sixth capacitor 11 is grounded. The NR port of the reference voltage module 14 is grounded after passing through the seventh capacitor 12. The output end of the reference voltage module 14 is connected to the comparison and discrimination circuit.

[0026] The comparison and discrimination circuit includes a first comparator 13, a third resistor 15, and a fourth resistor 16. The non-inverting input terminal of the first comparator 13 is connected to the other end of the first resistor 6, the inverting input terminal of the first comparator 13 is connected to the output terminal of the reference voltage module 14, the output terminal of the first comparator 13 is connected to one end of the third resistor 15 and one end of the fourth resistor 16, the other end of the third resistor 15 is connected to the output terminal of the power supply module 3, and the other end of the fourth resistor 16 is connected to the feedback processing circuit.

[0027] The feedback processing circuit includes a PNP transistor 17, an NPN transistor 18, a fifth resistor 19, a sixth resistor 20, a seventh resistor 21, and an eighth resistor 22. The base of the PNP transistor 17 is connected to the other end of the fourth resistor 16, the emitter of the PNP transistor 17 is connected to one end of the seventh resistor 21 and the output end of the power module 3, the collector of the PNP transistor 17 is connected to the collector of the NPN transistor 18, the other end of the seventh resistor 21, one end of the eighth resistor 22, and the inverting input end of the second comparator 27, the other end of the eighth resistor 22 is grounded, the emitter of the NPN transistor 18 is grounded after passing through the sixth resistor 20, the base of the NPN transistor 18 is connected to one end of the fifth resistor 19, and the other end of the fifth resistor 19 is connected to the output end of the air pressure detection circuit.

[0028] The air pressure detection circuit includes a ninth resistor 23, a tenth resistor 24, an eleventh resistor 25, a pressure switch 26, a twelfth resistor 29, a thirteenth resistor 30, a fourteenth resistor 31, a fifteenth resistor 32, and a third comparator 33. The pressure switch 26 is installed in the gas cylinder. One end of the ninth resistor 23 is connected to the output end of the power module 3, the other end of the ninth resistor 23 is connected to one end of the tenth resistor 24, the in-phase input end of the second comparator 27, and one end of the eleventh resistor 25. The other end of the tenth resistor 24 is grounded, and the other end of the eleventh resistor 25 is connected to the in-phase input end of the pressure switch 26. The 10MPa end is connected to the 14.4MPa end of the pressure switch 26, one end of the twelfth resistor 29, one end of the thirteenth resistor 30, and the in-phase input end of the third comparator 33 are connected, the other end of the twelfth resistor 29 is connected to one end of the fourteenth resistor 31 and the output end of the power supply module 3, the other end of the thirteenth resistor 30 is grounded, the other end of the fourteenth resistor 31 is connected to the inverting input end of the third comparator 33 and one end of the fifteenth resistor 32, the other end of the fifteenth resistor 32 is grounded, and the output end of the third comparator 33 and the output end of the second comparator 27 are connected to the input end of the drive circuit.

[0029] The driving circuit includes a sixteenth resistor 28, a seventeenth resistor 38, an eighth capacitor 39, a contactor 34, a diode 36, and a field effect transistor 37. One end of the sixteenth resistor 28 is connected to the output end of the power module 3, and the other end of the sixteenth resistor 28 is connected to the output end of the second comparator 27, the output end of the third comparator 33, one end of the seventeenth resistor 38, one end of the eighth capacitor 39, and the gate of the field effect transistor 37. The other end of the seventeenth resistor 38, the other end of the eighth capacitor 39, and the source of the field effect transistor 37 are grounded, and the drain of the field effect transistor 37 is connected to the grid power supply through the coil of the contactor 34. The diode 36 is connected in parallel to the two ends of the coil of the contactor 34. The grid power supply is connected to the compressed air motor 35 through the normally open contact of the contactor 34. The compressed air motor 35 is powered to drive the air pump to inflate the gas cylinder.

[0030] The contactor 34 is of model MZJ-200A, the diode 36 is of model 1N4007, the field effect tube 37 is of model IRF540, the pressure switch 26 is of model ZPM760, and the first comparator 13, the second comparator 27, and the third comparator 33 are all of model LM139.

[0031] When the engine of a special vehicle is not working, the battery provides power to the whole vehicle. The rated voltage of the on-board battery is +24V, and the maximum voltage will not exceed +26.5V when fully charged; when the engine is working, the engine drives the on-board generator to provide power to the whole vehicle. Since the on-board generator needs to charge the on-board battery when the engine is working, the output voltage of the on-board generator must be higher than the voltage of the on-board battery. The rated voltage of the on-board generator is +28V, and the voltage fluctuation range is between +27.5V and +28.5V. The present invention utilizes the grid voltage variation characteristics of special vehicles when the engine is not working and working, and selects +27V as the discrimination voltage. A grid voltage greater than +27V indicates that the engine is working, and a grid voltage less than +27V indicates that the engine is not working.

[0032] like Figure 2 As shown, a working method of an electrically driven compressed air device working synchronously with an engine comprises the following steps: Step 1: Turn on the main power switch of the special vehicle to power on; Step 2: Determine whether the engine is working by detecting the grid voltage. If the detected grid voltage is less than +27V, it means that the engine is not working. Disconnect the compressed air device drive circuit, stop charging, and continue to cycle to detect the grid voltage; if the detected grid voltage is greater than or equal to +27V, it means that the engine is working, and proceed to the next step; Step 3: Detect the cylinder pressure. If the cylinder pressure is less than 10MPa, proceed to step 4; if the cylinder pressure is between 10MPa and 14.4MPa, proceed to step 5; if the cylinder pressure is greater than 14.4MPa, proceed to step 6; Step 4: Connect the drive circuit, the compressed air motor 35 drives the air pump to rotate, inflate the gas cylinder, and then return to step 2; Step 5: The driving circuit maintains its original state, that is, if the driving circuit is originally in a disconnected state, the driving circuit continues to be disconnected; if the driving circuit is originally in a connected state, the driving circuit continues to be connected, and then returns to step 2; Step 6: Disconnect the drive circuit, stop inflation, and return to step 2.

[0033] Depend on Figure 1 It can be seen that the input end of the power module 3 is connected to the first capacitor 1 of 100uF and the second capacitor 2 of 0.1uF, and the output end of the power module 3 is connected to the third capacitor 4 of 10uF and the fourth capacitor 5 of 0.1uF, converting the special vehicle grid power supply into a +15V / 1A working power supply to power the circuit of the electrically driven compressed air device that works synchronously with the engine.

[0034] The first resistor 6 of 50K, the fifth capacitor 7 of 10uF, the second resistor 8 of 22K, the Zener diode 9, and the 10K adjustable resistor 10 together form a high-precision voltage sampling circuit. The Zener diode 9 model is 1N5222B, which stabilizes 2.5V. The first resistor 6 of 50K, the second resistor 8 of 22K, and the Zener diode 9 form a high-precision voltage divider circuit with an accuracy error of less than 0.1%. The 10K adjustable resistor 10 and the Zener diode 9 form a voltage fine-tuning circuit. During the debugging process, the error value is compensated by adjusting the resistance value of the 10K adjustable resistor 10. The fifth capacitor 7 of 10uF is a filter capacitor. When the grid voltage is +27V, the sampling voltage transmitted to the common-phase input terminal of the first comparator 13 is:

[0035] When the grid voltage is +27.1V, the sampling voltage transmitted to the non-inverting input terminal of the first comparator 13 is:

[0036] A 1uF sixth capacitor 11 , a 1uF seventh capacitor 12 , and a reference power supply module 14 form a reference power supply circuit. A Vout pin of the reference power supply module 14 outputs a 10V reference voltage which is transmitted to the inverting input terminal of the first comparator 13 .

[0037] The present invention utilizes the grid voltage variation characteristics of special vehicles when the engine is not working and working, and selects +27V as the discrimination voltage. When the engine is not working, the grid voltage is lower than +27V, the sampling voltage at the in-phase input end of the first comparator 13 is lower than the reference voltage 10V at the inverting input end, the internal triode of the first comparator 13 connects the output end with the negative pole of the power supply, and the output end of the first comparator 13 is grounded; when the engine is working, the grid voltage is higher than +27.1V, the sampling voltage at the in-phase input end of the first comparator 13 is higher than the reference voltage +10V at the inverting input end, the triode connected in series between the output end and the negative pole of the power supply in the first comparator 13 is cut off, the output end of the first comparator 13 is in a high impedance state, and is connected to the +15V power supply through the third resistor 15 with a resistance value of 5K, and outputs a high level.

[0038] A 50K fourth resistor 16 , an S9012 type PNP transistor 17 , an S9013 type NPN transistor 18 , a 50K fifth resistor 19 , a 1K sixth resistor 20 , a 10K seventh resistor 21 , and a 10K eighth resistor 22 constitute a reference voltage circuit of a second comparator 27 , and the output reference voltage is transmitted to the inverting input terminal of the second comparator 27 . There are three situations for this reference voltage: (a) when the engine is not working, the output end of the first comparator 13 is high level, and acts on the base of the S9012 type PNP transistor 17 through the 50K fourth resistor 16, the emitter and collector of the S9012 type PNP transistor 17 are turned on, and the reference voltage transmitted to the inverting input end of the second comparator 27 is about +15V; (b) when the engine is working and the output end of the second comparator 27 is low level, the S9012 type PNP transistor 17 and the S9013 type NPN transistor 18 are both cut off, and the +15V voltage is divided by the 10K seventh resistor 21 and the 10K eighth resistor 22, and transmitted to the second comparator 27. The reference voltage of the inverting input terminal is about +7.5V; (c) when the engine is working and the output terminal of the second comparator 27 is at a high level, the S9012 PNP transistor 17 is cut off, and the high level of the output terminal of the second comparator 27 is fed back to the base of the S9013 NPN transistor 18 through the 50K fifth resistor 19, and the collector and emitter of the S9013 NPN transistor 18 are turned on. At this time, the 10K eighth resistor 22 and the 1K sixth resistor 20 are connected in parallel, and the parallel resistance is about 0.91K. The +15V voltage is divided by the 10K seventh resistor 21 and the 0.91K resistor, and the reference voltage transmitted to the inverting input terminal of the second comparator 27 is about +1.3V; The pressure switch 26 is used to detect the air pressure of the compressed air device and is installed in the gas cylinder. The pressure switch is provided with two switch points of 10MPa and 14.4MPa, i.e., the air pressure value for starting inflation and the air pressure value for stopping inflation. When the gas pressure in the gas cylinder is lower than 10MPa, the 10MPa pin of the pressure switch 26 is disconnected from the ground pin, and the +15V voltage is divided by the 10K ninth resistor 23 and the 20K tenth resistor 24, and the comparison voltage transmitted to the in-phase input terminal of the second comparator 27 is about +10V. In the above-mentioned situation (a) when the engine is not working, the reference voltage of the inverting input terminal of the second comparator 27 is about +15V, the comparison voltage of the in-phase input terminal is less than the reference voltage of the inverting input terminal, and the second comparator 27 outputs a low level; in the above-mentioned situation (b) when the engine is working and the output terminal of the second comparator 27 is a low level, the reference voltage of the inverting input terminal of the second comparator 27 is about +7.5V, the comparison voltage of the in-phase input terminal is greater than the reference voltage of the inverting input terminal, and the second comparator 27 outputs a high level. At this time, situation (b) is transformed into situation (c). When the engine is running and the output of the second comparator 27 is high, the reference voltage of the inverting input of the second comparator 27 is about +1.3V, the comparison voltage of the non-inverting input is greater than the reference voltage of the inverting input, and the output of the second comparator 27 is still high.

[0039] When the gas cylinder pressure is higher than 10MPa, the 10MPa pin of the pressure switch 26 is connected to the ground pin. At this time, the 20K tenth resistor 24 and the 5K eleventh resistor 25 are connected in parallel, and the parallel resistance is about 4K. The +15V voltage is divided by the 10K ninth resistor 23 and the 4K resistor, and the comparison voltage transmitted to the in-phase input terminal of the second comparator 27 is about +4.3V; when the engine is in working state, the gas cylinder pressure is first lower than 10MPa, which will make the output terminal of the second comparator 27 high level, triggering the reference voltage of the inverting input terminal of the second comparator 27 from +7.5V to +1.3V. When the gas cylinder is inflated to higher than 10MPa, the comparison voltage of the in-phase input terminal of the second comparator 27 changes from +10V to +4.3V, but is still higher than +1.3V, and the output terminal of the second comparator 27 continues to maintain a high level. If the cylinder pressure is always higher than 10 MPa when the engine is in operation, the reference voltage of the inverting input terminal of the second comparator 27 is +7.5V, and the comparison voltage of the non-inverting input terminal is +4.3V. The comparison voltage of the non-inverting input terminal is less than the reference voltage of the inverting input terminal, and the second comparator 27 outputs a low level.

[0040] The +15V voltage is divided by the 10K fourteenth resistor 31 and the 10K fifteenth resistor 32, and the reference voltage transmitted to the inverting input terminal of the third comparator 33 is about +7.5V. When the gas pressure in the gas cylinder is lower than 14.4MPa, the 14.4MPa pin of the pressure switch 26 is disconnected from the ground pin, and the +15V voltage is divided by the 10K twelfth resistor 29 and the 20K thirteenth resistor 30, and the comparison voltage transmitted to the non-inverting input terminal of the third comparator 33 is about +10V. The comparison voltage at the non-inverting input terminal is greater than the reference voltage at the inverting input terminal, and the third comparator 33 outputs a high level; when the gas pressure in the gas cylinder is higher than 14.4MPa, the 14.4MPa pin of the pressure switch 26 is connected to the ground pin, and the +15V voltage is grounded through the 10K twelfth resistor 29, and the comparison voltage transmitted to the non-inverting input terminal of the third comparator 33 is about 0V. The comparison voltage at the non-inverting input terminal is less than the reference voltage at the inverting input terminal, and the third comparator 33 outputs a low level.

[0041] The 16th resistor 28 of 5K, the contactor 34, the compressed air motor 35, the diode 36, the field effect tube 37, the 17th resistor 38 of 12.5K, and the 8th capacitor 39 of 10uF form a compressed air device driving circuit. When the output end of the second comparator 27 and the output end of the third comparator 33 are both in high impedance state, the 17th resistor 38 of 12.5K and the fifth resistor 19 of 50K are connected in parallel, and the parallel resistance is about 10K. The +15V voltage is divided by the 16th resistor 28 of 5K and the 10K resistor, and the voltage loaded on the gate of the field effect tube 37 is about 10V. The source and drain of the field effect tube are turned on, and the positive electrode of the vehicle power grid passes through the coil of the contactor 34 to the field effect tube 37, and then to the negative electrode of the vehicle power grid to form a loop. The normally open contact of the contactor 34 is pulled in, and the compressed air motor 35 is powered on to drive the air pump to inflate the gas cylinder. The eighth capacitor 39 of 10uF is the gate filter capacitor of the field effect transistor 37, and the diode 36 is the coil freewheeling diode of the contactor 34.

Claims

1. An electrically driven compressed air device that works synchronously with an engine, characterized in that: The invention comprises a power supply circuit, a voltage sampling circuit, a reference voltage circuit, a comparison and discrimination circuit, a feedback processing circuit, an air pressure detection circuit and a driving circuit. The grid power supply is connected to the input end of the power supply circuit, the input end of the voltage sampling circuit and the driving circuit; the output end of the power supply circuit is connected to the reference voltage circuit, the comparison and discrimination circuit, the feedback processing circuit and the air pressure detection circuit; the output end of the reference voltage circuit and the output end of the voltage sampling circuit are connected to the input end of the comparison and discrimination circuit; the output end of the comparison and discrimination circuit and the output end of the air pressure detection circuit are connected to the input end of the feedback processing circuit; the output end of the feedback processing circuit is connected to the input end of the air pressure detection circuit; the output end of the air pressure detection circuit is connected to the input end of the driving circuit; and the output end of the driving circuit is connected to the compressed air motor.

2. The electrically driven compressed air device that works synchronously with the engine according to claim 1, characterized in that: The power supply circuit includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a power module. The power module model is LM7815. The grid power supply is connected to one end of the first capacitor, one end of the second capacitor, and an input end of the power module. The other end of the first capacitor and the other end of the second capacitor are grounded. The output end of the power module is connected to one end of the third capacitor and one end of the fourth capacitor. The other end of the third capacitor and the other end of the fourth capacitor are grounded.

3. The electrically driven compressed air device that works synchronously with the engine according to claim 2, characterized in that: The voltage sampling circuit includes a first resistor, a second resistor, an adjustable resistor, a fifth capacitor, and a voltage-stabilizing diode. One end of the first resistor is connected to a power grid, the other end of the first resistor is connected to one end of the fifth capacitor and one end of the second resistor, the other end of the second resistor is connected to the cathode of the voltage-stabilizing diode, the cathode of the voltage-stabilizing diode is grounded after passing through the adjustable resistor, and the other end of the fifth capacitor and the anode of the voltage-stabilizing diode are grounded.

4. The electrically driven compressed air device that works synchronously with the engine according to claim 3, characterized in that: The reference voltage circuit includes a sixth capacitor, a seventh capacitor and a reference voltage module. The reference voltage module model is REF102BP. One end of the sixth capacitor is connected to the V+ end of the reference voltage module and the output end of the power supply module. The other end of the sixth capacitor is grounded. The NR port of the reference voltage module is grounded after passing through the seventh capacitor. The output end of the reference voltage module is connected to the comparison and discrimination circuit.

5. The electrically driven compressed air device that works synchronously with the engine according to claim 4, characterized in that: The comparison and discrimination circuit includes a first comparator, a third resistor, and a fourth resistor. The non-inverting input terminal of the first comparator is connected to the other end of the first resistor, the inverting input terminal of the first comparator is connected to the output terminal of the reference voltage module, the output terminal of the first comparator is connected to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is connected to the output terminal of the power supply module, and the other end of the fourth resistor is connected to the feedback processing circuit.

6. The electrically driven compressed air device that works synchronously with the engine according to claim 5, characterized in that: The feedback processing circuit includes a PNP transistor, an NPN transistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor. The base of the PNP transistor is connected to the other end of the fourth resistor, the emitter of the PNP transistor is connected to one end of the seventh resistor and the output end of the power module, the collector of the PNP transistor is connected to the collector of the NPN transistor, the other end of the seventh resistor, one end of the eighth resistor, and the inverting input end of the second comparator, the other end of the eighth resistor is grounded, the emitter of the NPN transistor is grounded after passing through the sixth resistor, the base of the NPN transistor is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to the output end of the air pressure detection circuit.

7. The electrically driven compressed air device that works synchronously with the engine according to claim 6, characterized in that: The air pressure detection circuit includes a ninth resistor, a tenth resistor, an eleventh resistor, a pressure switch, a second comparator, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a third comparator. The pressure switch is installed in a gas cylinder. One end of the ninth resistor is connected to the output end of the power module, the other end of the ninth resistor is connected to one end of the tenth resistor, the non-inverting input end of the second comparator, and one end of the eleventh resistor. The other end of the tenth resistor is grounded. The other end of the eleventh resistor is connected to the 10MPa end of the pressure switch, the 14.4MPa end of the pressure switch is connected to one end of the twelfth resistor, one end of the thirteenth resistor, and the non-inverting input end of the third comparator. The other end of the twelfth resistor is connected to one end of the fourteenth resistor and the output end of the power module, the other end of the thirteenth resistor is grounded, the other end of the fourteenth resistor is connected to the inverting input end of the third comparator and one end of the fifteenth resistor, the other end of the fifteenth resistor is grounded, and the output end of the third comparator and the output end of the second comparator are connected to the input end of the drive circuit.

8. The electrically driven compressed air device that works synchronously with the engine according to claim 7, characterized in that: The driving circuit includes a sixteenth resistor, a seventeenth resistor, an eighth capacitor, a contactor, a diode, and a field effect transistor. One end of the sixteenth resistor is connected to the output end of the power module, the other end of the sixteenth resistor is connected to the output end of the second comparator, the output end of the third comparator, one end of the seventeenth resistor, one end of the eighth capacitor, and the gate of the field effect transistor. The other end of the seventeenth resistor, the other end of the eighth capacitor, and the source of the field effect transistor are grounded, the drain of the field effect transistor is connected to the grid power supply through the coil of the contactor, the diode is connected in parallel to the two ends of the coil of the contactor, the grid power supply is connected to the compressed air motor through the normally open contact of the contactor, and the compressed air motor is powered on to drive the air pump to inflate the gas cylinder.

9. The electrically driven compressed air device that works synchronously with the engine according to claim 8, characterized in that: The contactor model is MZJ-200A, the diode model is 1N4007, the field effect tube model is IRF540, the pressure switch model is ZPM760, and the first comparator, the second comparator, and the third comparator model are all LM139.

10. A working method of an electrically driven compressed air device working synchronously with an engine, applied to the electrically driven compressed air device working synchronously with an engine as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Turn on the main power switch of the special vehicle to power on; Step 2: Determine whether the engine is working by detecting the grid voltage. If the detected grid voltage is less than +27V, it means that the engine is not working. Disconnect the compressed air device drive circuit, stop charging, and continue to cycle to detect the grid voltage; if the detected grid voltage is greater than or equal to +27V, it means that the engine is working, and proceed to the next step; Step 3: Detect the cylinder pressure. If the cylinder pressure is less than 10MPa, proceed to step 4; if the cylinder pressure is between 10MPa and 14.4MPa, proceed to step 5; if the cylinder pressure is greater than 14.4MPa, proceed to step 6; Step 4: Connect the drive circuit, the compressed air motor drives the air pump to rotate, inflate the gas cylinder, and then return to step 2; Step 5: The driving circuit maintains its original state, that is, if the driving circuit is originally in a disconnected state, the driving circuit continues to be disconnected; if the driving circuit is originally in a connected state, the driving circuit continues to be connected, and then returns to step 2; Step 6: Disconnect the drive circuit, stop inflation, and return to step 2.

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