CN111749824B - High-speed fuel injector driving circuit with fault diagnosis function and judgment method - Google Patents

High-speed fuel injector driving circuit with fault diagnosis function and judgment method Download PDF

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Publication number
CN111749824B
CN111749824B CN202010620773.5A CN202010620773A CN111749824B CN 111749824 B CN111749824 B CN 111749824B CN 202010620773 A CN202010620773 A CN 202010620773A CN 111749824 B CN111749824 B CN 111749824B
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circuit
current
low
mos tube
fault
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CN111749824A (en
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桑印
李鹏豪
周琴
王文成
张永林
曹钰
吴竞
张朦朦
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Chongqing Hongjiang Machinery Co Ltd
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Chongqing Hongjiang Machinery Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
    • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
    • H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • F02D2041/2086—Output circuits, e.g. for controlling currents in command coils with means for detecting circuit failures
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/20—Output circuits, e.g. for controlling currents in command coils
    • F02D2041/2086—Output circuits, e.g. for controlling currents in command coils with means for detecting circuit failures
    • F02D2041/2093—Output circuits, e.g. for controlling currents in command coils with means for detecting circuit failures detecting short circuits

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

The invention discloses a high-speed fuel injector driving circuit with fault diagnosis and a judging method, wherein the high-speed fuel injector driving circuit comprises a CPU, a high-end driving circuit, a low-end driving circuit, a fuel injector switching circuit, a circuit sampling circuit and a comparison circuit; the high-end driving circuit, the low-end driving circuit, the current sampling circuit and the comparison circuit are respectively electrically connected with the CPU; and the fuel injector switch circuit is respectively and electrically connected with the high-end driving circuit, the low-end driving circuit and the current sampling circuit. The invention not only has the function of controlling the oil injector, but also has the function of judging the fault of the oil injector.

Description

High-speed fuel injector driving circuit with fault diagnosis function and judgment method
Technical Field
The invention relates to the technical field of driving circuits of fuel injectors of diesel engine fuel systems, in particular to a high-speed fuel injector driving circuit with fault diagnosis and a judgment method.
Background
In diesel fuel systems for vehicles and ships, high-speed fuel injectors are usually used as key parts of actuators of fuel injection systems. If the oil injector fails in driving, the normal work of the diesel engine can be directly influenced, even the diesel engine is damaged and the safety of driving and traveling is influenced, so that the driving circuit of the high-speed oil injector needs to have high-reliability performance, and the driving circuit can be diagnosed in time after the driving circuit fails and take related actions to avoid the damage of the diesel engine. In the using process, because the injection energy of the diesel engine is huge, the current of the driving circuit has very strict requirements, and the faults of the oil injector and the driving circuit are easily caused. Therefore, the high-speed fuel injector driving circuit with fault diagnosis and the judgment method are provided.
Disclosure of Invention
The invention aims to provide a high-speed fuel injector driving circuit with fault diagnosis and a judgment method, which can realize the diagnosis of a series of faults such as driving circuit faults and fuel injector faults and can clearly diagnose fault points.
In a first aspect, the invention provides a high-speed fuel injector driving circuit with fault diagnosis, which comprises a CPU, a high-end driving circuit, a low-end driving circuit, a fuel injector switching circuit, a current sampling circuit and a comparison circuit, wherein the high-end driving circuit is connected with the high-end driving circuit;
the high-end driving circuit, the low-end driving circuit, the current sampling circuit and the comparison circuit are respectively electrically connected with the CPU; the fuel injector switch circuit is respectively and electrically connected with the high-end driving circuit, the low-end driving circuit and the current sampling circuit; the CPU outputs control signals to a high-end driving circuit and a low-end driving circuit, the high-end driving circuit is used for completing the starting of a high-end MOS tube in the oil sprayer switching circuit, the low-end driving circuit is used for completing the starting of a low-end MOS tube in the oil sprayer switching circuit, the low-end MOS tube is used for selecting an oil sprayer, and the high-end MOS tube is used for controlling current; after the MOS tube is opened, current flows through the oil injector and generates required electromagnetic force to drive the oil injector to finish oil injection;
the current of the oil sprayer is closely related to the magnitude of electromagnetic force, so that the current of the oil sprayer needs to be accurately controlled, the current of the oil sprayer needs to be subjected to closed-loop control in order to accurately control the current, when the current value is lower than a set value, a CPU sends a signal to open a high-end MOS (metal oxide semiconductor) tube, the power voltage is applied to the oil sprayer again, and the current gradually rises again; when the current value is higher than the set value, the CPU withdraws the signal, the high-end MOS tube is closed, and the current gradually decreases. The current sampling is completed by adopting a precise sampling resistor, and the current is amplified by a precise amplifier and then is transmitted to an FADC port of a CPU, so that the current is accurately monitored. In order to save CPU resources and reduce the workload of the CPU, the current sampling is optimally designed: one group of oil injector driving currents adopt a main circuit current sampling resistor, and 1 path of FADC is used for rapid sampling; and (3) not sampling the current of each branch, comparing the current of each branch with the total current, finally outputting a 0-5V high-low level signal to an IO port of the CPU, and finally judging the short circuit fault of the branch of the oil sprayer according to the signal.
The current sampling circuit is used for collecting current signals of the oil sprayer and diagnosing faults of the driving circuit based on the current signals, and the diagnosed faults comprise high-end MOS tube short-circuit faults, high-end MOS tube open-circuit faults, low-end MOS tube short-circuit faults, low-end MOS tube open-circuit faults, oil sprayer short-circuit faults and oil sprayer open-circuit faults.
Further, the FADC sampling frequency of the CPU is more than or equal to 10MHz, and an independent kernel is provided for calculation.
Further, the oil injector switch circuit consists of two paths of high-end MOS tubes, K paths of low-end MOS tubes and K +1 sampling resistors; wherein K is the number of the oil injectors;
one high-end MOS tube is a high-end high-voltage 48V MOS tube and is used for shortening the current rise time of the oil sprayer and realizing the quick opening of the oil sprayer;
one high-end MOS tube is a high-end low-voltage 24V MOS tube and is used for maintaining the opening of the oil injector and keeping the current stable;
the low-end MOS tube is used as a cylinder selection switch to select the oil injector to be driven;
k sampling resistors are respectively and correspondingly arranged on S poles of the K low-end MOS tubes and used for detecting the current condition of each oil injector; and the other sampling resistor is arranged between GND and K sampling resistors and is used for detecting the overall circuit and controlling the overall current.
Further, the high-end driving circuit comprises two high-end driving units, wherein one high-end driving unit is a 48V high-end driving circuit and is used for shortening the current rise time of the oil sprayer and realizing the quick starting of the oil sprayer; and the other path is a 24V high-end driving circuit used for realizing the stable control of current chopping of the oil injector.
Further, the low-side driving circuit includes m low-side driving units, where m = (K + 1)/2 when K is an odd number, and m = K/2 when K is an even number; and the low-end driving circuit is used for controlling the on-off of a low-end MOS tube in the fuel injector switching circuit.
Further, the current sampling circuit comprises K branch current sampling units and 1 total current sampling unit;
the comparison circuit comprises K comparators; the K comparators are respectively connected with the K branch current sampling units in a one-to-one correspondence manner, and the current collected by the branch current sampling units is sent to the negative input ends of the corresponding comparators; the K-path comparison unit is also respectively connected with the total current sampling unit, the current collected by the total current sampling unit is amplified and then sent to the positive input end of each comparator, the output end of each comparator is connected with the single-chip IO port of the CPU, and the output result is sent to the single-chip IO port of the CPU.
In a second aspect, the method for judging a fault of a high-speed injector driving circuit according to the present invention, which uses the high-speed injector driving circuit with fault diagnosis according to the present invention, includes:
(1) short circuit fault of high-end MOS tube
When no high-end driving signal exists, judging whether the current flows through the oil injector, if so, indicating that the high-end MOS tube has a short-circuit fault;
(2) high-end MOS tube open circuit fault
When the high-end high-voltage 48V driving signal is enabled, no current passes through the oil injector, and when the high-end low-voltage 24V driving signal is enabled, the current flows through the oil injector, and the high-end high-voltage 48V MOS tube is judged to be disconnected;
when the starting current is normal, but the current is always reduced in the enabling process of the high-end low-voltage 24V driving signal, and when the current is smaller than a certain specific value, the high-end low-voltage 24V MOS tube is judged to have an open-circuit fault;
(3) short circuit fault of low-side MOS tube
If a certain branch circuit has a short circuit of the low-end MOS tube, when all other branch circuits work, the current of other branch circuits is lower than the total sampling resistance current, the comparison circuit finally outputs a high level by comparing the branch circuit current with the total sampling resistance current, and the CPU acquires the high level, so that the short circuit fault of the low-end MOS tube can be judged; when the sampling resistor works, the current of the short-circuit branch is equal to the current of the total sampling resistor; the fault branch can be finally determined through the two pieces of information;
(4) open circuit fault of low-end MOS tube or oil sprayer
When a cylinder selection signal acts, no current flows through the oil injector when a high-end high-voltage 48V driving signal and a subsequent high-end low-voltage 24V driving signal act, and if the current value is always kept at the 0 point position, the low-end MOS tube is judged to be in an open circuit or the oil injector is judged to be in an open circuit fault;
(5) short circuit fault of oil injector
And judging the time for reaching the preset current under the driving action of the high-end high-voltage signal, and if the time is less than 0.5 time of the normal time, judging that the load of the oil sprayer has a short-circuit fault.
The invention has the following advantages: the fault diagnosis method has the basic function requirements of multi-path oil sprayer driving and the fault diagnosis function of an oil sprayer driving circuit, and the faults which can be diagnosed comprise a low-end MOS tube short-circuit fault, a low-end MOS tube open-circuit fault, a high-end MOS tube short-circuit fault, a high-end MOS open-circuit fault, an oil sprayer short-circuit fault and the like. Meanwhile, an overcurrent protection function is arranged on a hardware circuit, and double protection is formed by the overcurrent protection function and the current protection function of software. In addition, only a small amount of CPU resources are occupied, and accurate and quick response of fault judgment is realized.
Drawings
FIG. 1 is a block diagram of a system according to the present embodiment;
fig. 2 is a circuit diagram of a high-side driving unit in the present embodiment;
FIG. 3 is a circuit diagram of a low-side driving unit in the present embodiment;
fig. 4 is a circuit diagram of a fuel injector switching circuit in the present embodiment;
fig. 5 is a circuit diagram of a current sampling unit in the present embodiment;
fig. 6 is a circuit diagram of a comparator in the present embodiment;
in the figure: 1. the device comprises a CPU, 2, a high-end driving circuit, 3, a low-end driving circuit, 4, an oil sprayer switching circuit, 5, a current sampling circuit, 6 and a comparison circuit.
Detailed Description
The present technology is further described below with reference to the accompanying drawings:
in this embodiment, a high-speed injector driving circuit with fault diagnosis includes a CPU1, a high-side driving circuit 2, a low-side driving circuit 3, an injector switching circuit 4, a circuit sampling circuit 5, and a comparison circuit 6. As shown in fig. 1, the high-side driving circuit 2, the low-side driving circuit 3, the current sampling circuit 5 and the comparison circuit 6 are electrically connected to a CPU1 respectively; and the fuel injector switch circuit 4 is respectively and electrically connected with the high-end driving circuit 2, the low-end driving circuit 3 and the current sampling circuit 5.
In this embodiment, the CPU1 selects a high-speed sampling channel and has multiple cores or a coprocessor, so as to satisfy fast sampling of independent current sampling. Such as: TC1797 chip of England flying.
In this embodiment, the high-side driving circuit includes two high-side driving units, wherein one high-side driving unit is a 48V high-side driving circuit, and is used to shorten the current rise time of the fuel injector and realize the quick start of the fuel injector; and the other path is a 24V high-end driving circuit used for realizing the stable control of current chopping of the oil injector.
As shown in fig. 2, the high-side driving unit includes a chip U1, a resistor R1, a resistor R2, a resistor R3, a diode D1, a diode D2, a diode D3, a capacitor C1, and a capacitor C2; one end of the capacitor C1 is connected with VCC15V, the other end of the capacitor C1 is grounded, one end of a resistor R1 is connected with an IO pin of a CPU, the other end of the resistor R1 is connected with a pin 2 of a chip U1, a pin 1 of the chip U1 is connected with a pin 5 of the chip U1 through a resistor R2, a diode D1 and a capacitor C2, a pin 5 of the chip U1 is connected with a pin 8 of the chip U3652 through a diode D3, a pin 7 of the chip U1 is connected with an oil injector switch circuit through a resistor R3, and a diode D2 is connected with the resistor R3 in parallel.
In this embodiment, the chip adopted by the chip U1 is an IRS2127 having an overcurrent protection function, and when the current exceeds a set value, the output port thereof is closed in time, and finally no signal is output, the high-side MOS transistor is closed, and the current of the load is gradually released, thereby avoiding the device damage caused by the abnormal current as much as possible.
In this embodiment, the low-side driving circuit includes m low-side driving units, where m = (K + 1)/2 when K is an odd number, and m = K/2 when K is an even number; and the low-end driving circuit is used for controlling the on-off of a low-end MOS tube in the fuel injector switching circuit.
As shown in fig. 3, the low-side driving unit includes a chip U2, a resistor R5, a resistor R6, a resistor R7, a resistor R8, and a capacitor C3; the pin 2 of the chip U2 is connected with the CPU through a resistor R5, the pin 4 of the chip U2 is connected with the CPU through a resistor R6, the pin 7 of the chip U2 is connected with an oil injector switch circuit through a resistor R7, the pin 5 of the chip U2 is connected with the oil injector switch circuit through a resistor R8, and the pin 6 of the chip U2 is grounded through a capacitor C3.
In this embodiment, the chip U2 selects a driver chip MIC4124 with a dual-channel low-side MOS transistor, which forms a cylinder selection circuit together with a low-side MOS transistor in the injector switch circuit. The function is to select a certain injector load to enable the function. If the number of the fuel injectors is four, the low-end driving circuit needs to comprise 2 low-end driving units.
As shown in fig. 4, the injector switching circuit is composed of two high-side MOS transistors, K low-side MOS transistors, and K +1 sampling resistors; wherein K is the number of fuel injectors. One high-end MOS tube Q5 is a high-end high-voltage 48V MOS tube and is used for shortening the current rise time of the oil sprayer and realizing the quick opening of the oil sprayer; one high-end MOS tube Q6 is a high-end low-voltage 24V MOS tube and is used for maintaining the opening of the oil injector and keeping the current stable; the hold time is typically more than tens of times longer than the on time.
As shown in fig. 4, the low-side MOS transistor is used as a cylinder selection switch to select a fuel injector to be driven; if the number of the oil injectors is four, the number of the low-end MOS tubes is four, and the low-end MOS tubes are respectively an MOS tube Q1, an MOS tube Q2, an MOS tube Q3 and an MOS tube Q4.
As shown in fig. 4, K sampling resistors are respectively disposed at the S-poles of the K low-side MOS transistors for detecting the current condition of each injector, and another sampling resistor is disposed between GND and the K sampling resistors for detecting the overall circuit and controlling the overall current. If the number of the fuel injectors is four, the sampling resistors are five and are respectively a resistor R10, a resistor R11, a resistor R12, a resistor R13 and a resistor R14.
As shown in fig. 5, the current sampling circuit includes K branch current sampling units and 1 total current sampling unit; if the number of the oil injectors is four, the number of the branch current sampling units is four. The circuit of the branch current sampling unit is the same as that of the total current sampling unit. The branch current sampling unit comprises a chip U3, a resistor R15, a capacitor C4 and a capacitor C5, wherein a pin 1 of the chip U3 is grounded through a resistor R15 and a capacitor C4, a pin 3 and a pin 4 of the chip U3 are connected with corresponding sampling resistors, and a pin 5 of the chip U3 is grounded through a capacitor C5.
In this embodiment, the chip U3 adopts AD8211 to perform differential current collection, and has the characteristics of fixed amplification factor, high stability, small temperature drift and the like.
As shown in fig. 6, the comparison circuit includes K comparators, each comparator is an LM331, a positive input end of the comparator is connected to the output end of the total current after amplification, and a negative input end of the comparator is connected to the voltage output of each branch circuit after current amplification. And the final output result of each comparator is connected with the IO port of the CPU.
The driving logic sequence of the oil sprayer switching circuit is that the single chip microcomputer preferentially selects one way of oil sprayer to enable, the starting current rising process of the oil sprayer is completed through the high-end high-voltage 48V MOS tube after a certain time delay, the subsequent maintaining current balance type adopts the high-end low-voltage 24V MOS tube to complete the actions, and after the driving execution is completed, the high-end driving and the low-end driving are simultaneously closed.
In this embodiment, a method for judging a fault of a high-speed injector driving circuit, which uses the high-speed injector driving circuit with fault diagnosis described in this embodiment, includes:
(1) short circuit fault of high-end MOS tube
Because the high-end MOS tubes act on all the oil injectors, when the high-end MOS tubes are in short circuit fault, and any cylinder selection signal acts on the low-end MOS tubes, the oil injectors immediately generate a current rising process. The main judgment point is that whether the current flows through the oil injector when no high-end driving signal exists, and if so, the short-circuit fault of the high-end MOS tube is explained. At this time, it is necessary to replace the high-side MOS transistor or detect whether the high-side driving signal is correct.
(2) High-end MOS tube open circuit fault
When a high-end MOS (metal oxide semiconductor) open circuit fault occurs, the four driving currents (taking 4 oil injectors as an example) all have a consistent fault phenomenon. Because the high-end high-voltage 48V MOS tube and the high-end low-voltage 24V MOS tube have different functions, the fault phenomenon also has certain difference. The high-end high-voltage 48V MOS tube is broken, the phenomenon is that no circuit is opened, and whether a fault occurs can be judged according to the current condition when the singlechip gives a high-end high-voltage driving signal. When the signal is finished, no current is generated, and when the current appears when the high-side low-voltage 24V MOS tube is driven, the high-side high-voltage 48V MOS tube is judged to be open circuit. When the high-side low-voltage 24V MOS tube has a fault, the opening current is normal, but if the current is always reduced in the enabling process of the high-side low-voltage driving signal, the abnormity of the high-side low-voltage 24V MOS tube can be indicated. In order to simplify the judgment, whether the current is too small or not is judged in the enabling process of the high-end low-voltage 24V driving signal, and the judgment value is usually set to be 0.5-0.8 times of the holding current. When the current is too small, the open-circuit fault of the high-end low-voltage 24V MOS tube can be judged.
(3) Short circuit fault of low-side MOS tube
If a branch has a short circuit of low side MOS transistors, it can be considered as always existing in the selected state. When all other branches work, two branches can be selected. Due to the adoption of the method of total current control, the short-circuit current and the normal branch have current flowing through, so that the current of the normal branch is lower than the total sampling resistance current, the comparison circuit finally outputs a high level by comparing the branch current with the total sampling resistance current, and the CPU acquires the high level, so that the short-circuit fault of the low-end MOS tube can be judged. When the short-circuit branch circuit works, the current of the short-circuit branch circuit is equal to the current of the total sampling resistor. And finally determining the fault branch by the two pieces of information.
(4) Open circuit fault of low-end MOS tube
When a low side MOS transistor open circuit fault occurs, the equivalent result is no effective load access, which is equivalent to an injector open circuit fault. The failure phenomena are as follows: when the cylinder selection signal is applied, no current flows through the fuel injector when the high-end high-voltage 48V driving signal and the subsequent high-end low-voltage 24V driving signal are applied, and the current value is always kept at the 0 point position. The low-end MOS tube is broken or the fuel injector is broken.
(5) Short circuit fault of oil injector
When the oil injector is in short circuit fault, the electrical characteristics of the electromagnetic load are changed. The high-voltage signal driving function at the high end is judged to be the time reaching the set current, and if the time is less than 0.5 time of the normal time, the load of the oil injector can be judged to have a short-circuit fault. In addition, the rising speed is extremely high, and the protection current of the high-end driving chip is instantly achieved. The high side high voltage driver chip U1 will also send a fault indication to the cpu for collection.
(6) Open circuit fault of oil injector
When the fuel injector is in an open circuit fault, the equivalent result is that no effective load is connected, which is equivalent to the open circuit fault of the low-end MOS tube. The failure phenomena are as follows: when the cylinder selection signal is applied, no current flows through the fuel injector when the high-end high-voltage 48V driving signal and the subsequent high-end low-voltage 24V driving signal are applied, and the current value is always kept at the 0 point position. The low-end MOS tube is broken or the fuel injector is broken.
The high-speed fuel injector driving circuit with fault diagnosis is suitable for driving control and fault diagnosis of high-speed fuel injectors such as an electric control common rail fuel injector, an electric control monoblock pump and a gas valve.

Claims (6)

1. A fault judgment method of a high-speed fuel injector driving circuit is characterized in that the high-speed fuel injector driving circuit with fault diagnosis is adopted, and the high-speed fuel injector driving circuit comprises a CPU (1), a high-end driving circuit (2), a low-end driving circuit (3), a fuel injector switch circuit (4), a current sampling circuit (5) and a comparison circuit (6);
the high-end drive circuit (2), the low-end drive circuit (3), the current sampling circuit (5) and the comparison circuit (6) are respectively electrically connected with the CPU (1); the fuel injector switch circuit (4) is respectively and electrically connected with the high-end drive circuit (2), the low-end drive circuit (3) and the current sampling circuit (5); the CPU outputs control signals to a high-end drive circuit (2) and a low-end drive circuit (3), the high-end drive circuit (2) is used for completing the starting of a high-end MOS (metal oxide semiconductor) tube in an oil sprayer switch circuit (4), the low-end drive circuit (3) is used for completing the starting of a low-end MOS tube in the oil sprayer switch circuit (4), the low-end MOS tube is used for selecting an oil sprayer, and the high-end MOS tube is used for controlling current; after the MOS tube is opened, current flows through the oil injector and generates required electromagnetic force to drive the oil injector to finish oil injection;
the current sampling circuit is used for collecting current signals of the oil sprayer and diagnosing faults of the driving circuit based on the current signals, and the diagnosed faults comprise a high-end MOS (metal oxide semiconductor) tube short-circuit fault, a high-end MOS tube open-circuit fault, a low-end MOS tube short-circuit fault, a low-end MOS tube open-circuit fault, an oil sprayer short-circuit fault and an oil sprayer open-circuit fault; the method comprises the following steps:
(1) short circuit fault of high-end MOS tube
When no high-end driving signal exists, judging whether the current flows through the oil injector, if so, indicating that the high-end MOS tube has a short-circuit fault;
(2) high-end MOS tube open circuit fault
When the high-end high-voltage 48V driving signal is enabled, no current passes through the oil injector, and when the high-end low-voltage 24V driving signal is enabled, the current flows through the oil injector, and the high-end high-voltage 48V MOS tube is judged to be disconnected;
when the starting current is normal, but the current is always reduced in the enabling process of the high-end low-voltage 24V driving signal, and when the current is smaller than a certain specific value, the high-end low-voltage 24V MOS tube is judged to have an open-circuit fault;
(3) short circuit fault of low-side MOS tube
If a certain branch circuit has a short circuit of the low-end MOS tube, when all other branch circuits work, the current of other branch circuits is lower than the total sampling resistance current, the comparison circuit finally outputs a high level by comparing the branch circuit current with the total sampling resistance current, and the CPU judges that the short circuit fault of the low-end MOS tube occurs if the CPU acquires the high level; when the sampling resistor works, the current of the short-circuit branch is equal to the current of the total sampling resistor; finally determining a fault branch through the two pieces of information;
(4) open circuit fault of low-end MOS tube or oil sprayer
When a cylinder selection signal acts, no current flows through the oil injector when a high-end high-voltage 48V driving signal and a subsequent high-end low-voltage 24V driving signal act, and if the current value is always kept at the 0 point position, the low-end MOS tube is judged to be in an open circuit or the oil injector is judged to be in an open circuit fault;
(5) short circuit fault of oil injector
And judging the time for reaching the preset current under the driving action of the high-end high-voltage signal, and if the time is less than 0.5 time of the normal time, judging that the load of the oil sprayer has a short-circuit fault.
2. The fault judgment method of the high-speed injector drive circuit according to claim 1, characterized by comprising: the FADC sampling frequency of the CPU (1) is more than or equal to 10MHz, and the CPU has an independent kernel for calculation.
3. The fault judgment method of the high-speed injector drive circuit according to claim 2, characterized by comprising: the oil sprayer switching circuit consists of two paths of high-end MOS tubes, K paths of low-end MOS tubes and K +1 sampling resistors; wherein K is the number of the oil injectors;
one high-end MOS tube is a high-end high-voltage 48V MOS tube and is used for shortening the current rise time of the oil sprayer and realizing the quick opening of the oil sprayer;
one high-end MOS tube is a high-end low-voltage 24V MOS tube and is used for maintaining the opening of the oil injector and keeping the current stable;
the low-end MOS tube is used as a cylinder selection switch to select the oil injector to be driven;
k sampling resistors are respectively and correspondingly arranged on S poles of the K low-end MOS tubes and used for detecting the current condition of each oil injector; and the other sampling resistor is arranged between GND and K sampling resistors and is used for detecting the overall circuit and controlling the overall current.
4. The fault judgment method of the high-speed injector drive circuit according to claim 3, characterized by comprising: the high-end driving circuit comprises two high-end driving units, wherein one high-end driving unit is a 48V high-end driving circuit and is used for shortening the current rise time of the oil sprayer and realizing the quick starting of the oil sprayer; and the other path is a 24V high-end driving circuit used for realizing the stable control of current chopping of the oil injector.
5. The fault judgment method of the high-speed injector drive circuit according to claim 4, characterized by comprising: the low-side driving circuit comprises m low-side driving units, wherein m = (K + 1)/2 when K is an odd number, and m = K/2 when K is an even number; and the low-end driving circuit is used for controlling the on-off of a low-end MOS tube in the fuel injector switching circuit.
6. The fault judgment method of the high-speed injector drive circuit according to claim 5, characterized by comprising: the current sampling circuit comprises K branch current sampling units and 1 total current sampling unit;
the comparison circuit comprises K comparators; the K comparators are respectively connected with the K branch current sampling units in a one-to-one correspondence manner, and the current collected by the branch current sampling units is sent to the negative input ends of the corresponding comparators; the K-path comparison unit is also respectively connected with the total current sampling unit, the current collected by the total current sampling unit is amplified and then sent to the positive input end of each comparator, the output end of each comparator is connected with the single-chip IO port of the CPU, and the output result is sent to the single-chip IO port of the CPU.
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CN102477927B (en) * 2010-11-24 2013-11-06 联创汽车电子有限公司 Fault simulating and driving current collecting circuit of oil sprayer of automobile engine
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