CN2553119Y - Gas port sequential jetting, all electric controlled diesel oil/natural gas two-fuel motor - Google Patents

Abstract

A port sequential injection, lean burn, fully electronically controlled diesel/natural gas dual fuel engine, which installs a natural gas port sequential injection device at the intake port of each cylinder of the engine, installs a proportional electromagnet on the fuel injection pump, and adds an electronic control System; natural gas port sequential injection device consists of an injection solenoid valve installed at the intake port of each cylinder and a solenoid valve seat for installing the solenoid valve. The natural gas route consists of a high-pressure gas cylinder, a natural gas filter, and a natural gas pressure reducing valve. The electronic control system consists of an electronic control unit and several sensors connected to the engine. The utility model has the advantages that: 1. the refitting project is simple. 2. Engine emission meets Euro III standard. 3. High substitution rate of natural gas. 4. It has good acceleration and deceleration characteristics and good driving performance. 5. It can realize timing and quantitative control of natural gas and precise control of diesel quantity. 6. The electronic control unit has strong interference ability and good reliability.

Description

Port sequential injection, lean burn, fully electronically controlled diesel/natural gas dual fuel engine

Field:

The invention relates to an automobile engine, in particular to a gas-port sequential injection, lean-burn, fully electronically controlled diesel/natural gas dual-fuel engine.

Background technique:

At present, domestically produced diesel/natural gas dual-fuel engines generally add a set of mechanical oil limiting devices to the diesel supply system of the original engine, which cannot precisely control the oil quantity and has poor emission indicators. In terms of natural gas supply, most of them use mechanical mixers or single-point electric control devices. The mechanical mixer is based on the principle of Venturi or orifice flow agent, and the natural gas control valve is pushed by a mechanical spring according to the air intake to complete the control of the natural gas supply. It is difficult for this device to accurately control the amount of natural gas and the excess air ratio when environmental factors change. In contrast, although the electronically controlled single-point injection mixer can accurately control the amount of natural gas, it also has the following defects as the mechanical mixer: 1. Due to the large difference in specific gravity between natural gas and air, the intake air in the intake manifold is divided layer, the air-fuel ratio of the mixture between the cylinders varies greatly, and it is prone to knocking and high emissions. 2. For turbochargers and two-stroke machines, due to the large valve overlap angle, the scavenging short circuit is caused, which increases the HC emission. 3. In order to burn natural gas at low load, the intake air volume must be reduced accordingly. For this purpose, a throttle valve must be installed on the intake passage, but the installation of a throttle valve will reduce the thermal efficiency of part load by about 20%.

Invention content:

The object of the present invention is to overcome the deficiencies in the above-mentioned prior art, and provide a kind of port sequential injection, lean burn, fully electronically controlled diesel/ Natural gas dual fuel engine.

The technical scheme of the present invention is: a kind of gas port sequential injection, lean burn, all-electric control diesel/natural gas dual-fuel engine comprises former diesel engine, natural gas supply system, diesel supply system and electronic control unit (ECU), is characterized in that: Install a natural gas port sequential injection device at the air intake of each cylinder of the engine, install a proportional electromagnet on the fuel injection pump, and add an electronic control system; The electromagnetic valve is composed of a solenoid valve and a solenoid valve seat for installing the solenoid valve. A natural gas distribution pipe is added to the solenoid valve seat, and the natural gas is guided to spray to the intake valve through the natural gas distribution pipe; the natural gas is routed through a high-pressure gas cylinder, a natural gas filter, The natural gas pressure reducing valve is composed of high-pressure gas cylinders connected to natural gas filters, natural gas filters connected to natural gas pressure reducing valves, natural gas pressure reducing valves connected to natural gas common rail pipes through hoses, and connected to the sequential injection device of natural gas ports connected; the electronic control system is composed of an electronic control unit and several sensors connected to the engine; the output end of the sensor is connected with the input end of the electronic control system, and the output end of the electronic control system is connected with the above-mentioned injection solenoid valve and proportional electromagnet .

The above-mentioned electronic control unit (ECU) selects Motorola MC68332 32-bit microprocessor for use, including microcontroller module, digital acquisition module, power drive and protection module, power supply module, communication module and display and alarm module; wherein the microcontroller module consists of crystal oscillator, Composed of memory and reset chip, they are all connected to MC6833232-bit microprocessor; digital acquisition module is composed of analog signal acquisition circuit, switch signal acquisition circuit and pulse signal acquisition circuit, analog signal acquisition circuit includes filter circuit, A/D module Converter, the input end of the filter circuit is connected to the sensor, the output end is connected to the input end of the A/D analog-to-digital converter, and the output end of the A/D analog-to-digital converter is connected to the interface of the MC6833232-bit microprocessor; the switch signal The input terminal of the low-pass filter in the acquisition circuit is connected to the output terminal of the start switch, the output terminal is connected to the input terminal of the Schmitt trigger, the output terminal of the Schmitt trigger is connected to the interface of the MC6833232-bit microprocessor, and the pulse The input end of the filter circuit in the signal acquisition circuit is connected to the output end of the sensor, the output end of the filter circuit is connected to the input end of the Schmitt trigger, and the output end of the Schmitt trigger is connected to the input end of the monostable circuit , the output end of the monostable circuit is connected to the interface of the MC6833232-bit microprocessor; the power drive and protection module is composed of the power drive tube TMOS and the power gate drive chip IR2127, and the input ends of the power gate drive chip IR2127 are respectively connected to the solenoid valve It is connected to the output terminal of the proportional electromagnet, and the output terminal is connected to the power drive tube; the power module adopts a step-down PWM switching power supply composed of MAX727 as the main chip; The SCI interface of the device is connected, and the output terminal is connected to the PC; the display and alarm module is composed of a triode connected to the MC6833232-bit microprocessor and an indicator light connected to it; the electronic throttle sensor in the above sensor is installed on the natural gas common rail pipe Natural gas temperature sensor, natural gas pressure sensor, intake air temperature sensor and intake air pressure sensor installed on the intake pipe, cooling water temperature sensor installed in the engine body, engine oil temperature sensor and engine oil pressure sensor, installed on the proportional solenoid The rack feedback sensor; the output terminals of these sensors are connected to the input terminal of the analog signal acquisition circuit in the electronic control system; the output of the synchronous signal sensor installed on the engine camshaft and the corner mark sensor installed above the engine flywheel disc The end is connected with the input end of the pulse signal acquisition circuit in the electronic control system.

The mouth of the high-pressure natural gas cylinder in the above-mentioned natural gas gas path is equipped with a natural gas manual cut-off valve, and a natural gas fast electronic cut-off valve is installed at the pipeline connected to the natural gas filter.

The input terminal of the above power module is connected in reverse parallel with a transient voltage suppression diode TVP.

The advantages of the present invention are: 1. The refitting project is simple. Except for the added natural gas supply system, proportional electromagnet and electronic control system (ECU), no changes have been made to the original engine. The driver only needs to control the accelerator pedal to realize perfect operation of the engine through the ECU. 2. The natural gas supply system mainly includes a natural gas circuit device and a set of natural gas port sequential injection device. The gas port sequential injection system can accurately control the injection amount and timing of natural gas and the air-fuel ratio (λ) of the combustion process in real time and quickly. "Cylinder deactivation technology" can be used at partial load to make the engine work in a better range of excess air coefficient. 3. A linear proportional electromagnet is added on the basis of the original diesel engine, and the proportional electromagnet pulls the handle of the oil pump to accurately control the amount of diesel oil in real time. Since the diesel pump and fuel injector of the original machine are retained, the fuel atomization will be poor and the fuel quantity control will be unstable when the fuel quantity is too small, so the minimum amount of diesel fuel for ignition is limited—10% of the total fuel quantity . 4. The engine has a good emission index, which can meet the European port emission index, and has good economy, and the minimum fuel economy is better than that of the original diesel engine (the quality of natural gas is converted into diesel oil according to the calorific value). 5. The electronic control unit (ECU) developed by Motorola MC68332 32-bit microprocessor can realize working condition judgment (starting, idling, acceleration, deceleration, overspeed working conditions), working mode selection (pure diesel, dual fuel work), MAP correction (Natural gas injection volume, diesel injection volume, number of deactivated cylinders), fault diagnosis, online communication, speed limit, smokeless start and other functions.

Description of drawings:

Fig. 1 is a structural representation of the present invention

Figure 2 is a sequential injection device for natural gas ports

Figure 3 is a schematic diagram of the electronic control system

Figure 4 is the logic block diagram of the electronic control system

Figure 5 is a block diagram of the microprocessor module

Figure 6 is a block diagram of the analog signal acquisition circuit

Figure 7 is a block diagram of the switch signal acquisition circuit

Figure 8 is a block diagram of the pulse signal acquisition circuit

Figure 9 is a circuit diagram of the power module

Fig. 10 is a workflow block diagram of the present invention

Figure 11 is a block diagram of the startup program

Figure 12 is a schematic diagram of the dual-fuel workflow

Figure 13 is a flowchart of the wheel cylinder algorithm

Figure 14 is a schematic diagram of oil volume calibration adjustment

Figure 15 is a flow chart of oil quantity calibration

Figure 16 is a logical block diagram of the number of deactivated cylinders, the amount of natural gas injection, and the amount of diesel injection corrected

Figure 17 is the flow chart of cylinder number correction

Figure 18 is a diagram of the speed fluctuation caused by the change of the number of cylinders

Fig. 19 is a rotation speed fluctuation diagram when oil and gas are switched at 1400 rpm.

Fig. 20 is a diagram of rotation speed fluctuation when oil and gas are switched at 2200 r/min.

Detailed ways:

As shown in Figures 1 and 2: a fully electronically controlled diesel/natural gas dual-fuel engine, including an engine body 15, a cylinder, a fuel injection pump 20 and a fuel injector 16, is characterized in that: at the air inlet of each cylinder of the engine The natural gas port sequential injection device is installed, the proportional electromagnet 22 is installed on the fuel injection pump, and the electronic control system 2 is added; the natural gas gas port sequential injection device is composed of injection solenoid valve 14 installed at the air inlet of each cylinder and used to install the electromagnetic valve. The solenoid valve seat 13 of the valve is formed, and the solenoid valve seat 13 is connected with the natural gas inlet valve 30 through the natural gas distribution pipe 29; the natural gas route is composed of a high-pressure gas cylinder 27, a natural gas filter 25, and a natural gas pressure reducing valve 24; The connection of the natural gas bottle, the natural gas filter and the natural gas pressure reducing valve are sequentially connected through the natural gas high pressure steel pipe 4, the natural gas pressure reducing valve is connected with the natural gas common rail pipe 5 through a hose, and connected with the sequential injection device of the natural gas port; A natural gas manual cut-off valve 28 is installed at the mouth of the high-pressure natural gas cylinder, and a natural gas electronic quick cut-off valve 26 is installed at the pipeline connected to the natural gas filter. The electronic control system in the present invention can realize working condition judgment (starting, idle speed, acceleration, deceleration, overspeed working condition), working mode selection (pure diesel oil, dual-fuel work), MAP correction (natural gas injection amount, diesel injection amount) and Troubleshooting. When the engine is running, the electronic control unit first judges the working condition according to the cooling water temperature, oil temperature, pressure, engine speed, and accelerator pedal position, and then selects the working mode according to the working condition to control the operation of the MAP.

In order to ensure that the engine works under the optimal excess air coefficient stored in MAP, the electronic control unit can correct the injection amount of natural gas, the number of cylinders stopped, and diesel injection in real time according to the actual conditions of engine operation (intake temperature, pressure, natural gas temperature, pressure). quantity. When the engine is running, the fault diagnosis module monitors the working conditions of each system in real time. When some unexpected situations occur, the alarm system will send out an alarm and turn the engine into a pure diesel working mode. The communication system can be conveniently used for engine maintenance and inspection. As shown in Figures 3 and 4: the electronic control system is composed of an electronic control unit and several sensors connected to the engine; the output end of the sensor is connected with the input end of the electronic control unit, and the output end of the electronic control unit is connected with the above-mentioned injection electromagnetic The valve is connected to the proportional solenoid. The above-mentioned electronic control unit selects Motorola MC68332 32-bit microprocessor, and its functional modules include a microcontroller module, a digital acquisition module, a power drive and protection module, a power supply module, a communication module, and a display and alarm module;

As shown in Figure 5: the microcontroller module is composed of crystal oscillator, memory RAM, ROM and reset chip Max707, which are all connected to MC6833232-bit microprocessor;

As shown in Figure 6: the digital acquisition module is composed of an analog signal acquisition circuit, a switch signal acquisition circuit and a pulse signal acquisition circuit. The analog signal acquisition circuit includes an RC filter circuit composed of capacitors and resistors, a TLC1543 analog-to-digital converter, and a filter circuit. The input end of the sensor is connected to sensors such as the temperature and pressure of natural gas and air, water temperature, engine oil temperature, battery voltage, position feedback information of the oil pump rack, and accelerator pedal signal, and the output end is connected to the input end of the TLC1543 analog-to-digital converter. The digital converter uses four signal lines Address, Data-Out, Clock, CS to connect with MOSI, MISO, SCK, and PCSI of the SPI interface of the MC6833232 microprocessor; the temperature signal and the battery voltage are input to the filter circuit after preprocessing.

As shown in Figure 7: the input end of the low-pass filter in the digital signal acquisition circuit is connected to the output end of the start switch, the output end is connected to the input end of the Schmitt trigger, and the output end of the Schmitt trigger is connected to the MC6833232 Microprocessor I/O interface connection.

As shown in Figure 8: the input end of the filter circuit in the pulse signal acquisition circuit is connected to the output end of the sensor, the output end of the filter circuit is connected to the input end of the Schmitt trigger, and the output end of the Schmitt trigger is connected to the single The input end of the steady state circuit is connected, and the output end of the monostable circuit is connected with the TPU module of the MC6833232 microprocessor; the monostable circuit is composed of a retriggerable multivibrator and a timing element. The power drive and protection module is composed of a power drive tube TMOS and a power gate drive chip IR2127. The input terminals of the power gate drive chip IR2127 are respectively connected to the output terminals of the solenoid valve and the proportional electromagnet, and the output terminals are connected to the power drive tube; As shown in Figure 9: the power supply module adopts the step-down PWM switching power supply composed of MAX727 as the main chip; the communication module adopts the MAX202 chip, the input end of the chip is connected to the SCI interface of the MC6833232 microprocessor, and the output end is connected to the PC; The input terminal of the power supply module is connected in reverse parallel with the transient voltage suppression diode TVP _c . The display and alarm module is composed of a triode connected with the MC6833232 microprocessor and an indicator light connected with it; The natural gas temperature sensor 6 on the rail pipe, the natural gas pressure sensor 7, the intake air temperature sensor 9 and the intake air pressure sensor 10 installed on the air intake pipe 12, the cooling water temperature sensor 17 installed in the engine block, the engine oil temperature sensor 18 and Engine oil pressure sensor 19, rack feedback sensor 21 installed on the proportional electromagnet; the output ends of these sensors are all connected with the input end of the analog signal acquisition circuit in the electronic control system; the output of synchronous signal sensor 23 and angle mark sensor 8 The end is connected with the input end of the pulse signal acquisition circuit in the electronic control system. Among them: corner mark and synchronous signal sensor: Hall sensor, providing corner mark and synchronous control signal. Temperature sensor: The intake air temperature and natural gas temperature sensors are both AD590, which is a current-type two-break device, designed using the basic principle that the voltage between the be poles of the transistor is proportional to the absolute temperature. Pressure sensor: The intake pressure and natural gas pressure sensor is a semiconductor piezoresistive sensor, which is composed of a pressure conversion element and an amplification circuit.

Accelerator pedal position and accelerator rod position sensor: used to sense the driver's accelerator pedal position and rack execution position, both adopt RP series rotary position sensor, which uses a symmetrical magnetic circuit to generate a linear magnetic field related to the rotor angle, and then uses high-precision The integrated chip converts it into a linear voltage.

Injection solenoid valve: a two-way normally closed valve, which is opened by driving pulses and kept for a certain period of time, thereby controlling the amount of natural gas injection, which is realized by the timing processing unit (TPU) of the single-chip microcomputer. Its driving voltage is 24V and its peak current is 15A.

Proportional electromagnet: An electromagnet is a component that uses electromagnetic force to convert electrical energy into mechanical energy. When the current is passed into the excitation coil of the electromagnet, the iron core of the electromagnet and the end surface of the armature show different magnetic properties, and they attract each other, so that the armature attracts to the iron core, thereby driving the rack to move, and its position is proportional to the current passed into the excitation coil. Proportional. The position of the rack is adjusted by the PID closed-loop control algorithm.

Fig. 10 is a working flow chart of the present invention. Including power-on self-test, system initialization, scale conversion, fault diagnosis, working condition judgment, timing calculation, MAP calculation, control quantity correction, communication management and other functional modules.

System initialization: Configure the relevant registers of SIM, TPU, QSM and other modules of MC68332, and perform system function settings.

Scale conversion: A/D results are averaged by software, and digital quantities are converted into corresponding physical values according to the sensor calibration curve.

Fault diagnosis: According to the sensor data and other related calculation results, judge the failure of the sensor and the actuator and the abnormal operation such as fire. On the one hand, the fault code is stored in the EEPROM, and on the other hand, the fault code parameter is provided to the TPU for driving the fault indication. lamp.

Working condition judgment: According to the driver's operation information, accelerator pedal and engine speed, the engine's fuel usage mode and engine operating condition are judged. Operating conditions include startup, idle, running, acceleration, deceleration, and speed limit.

MAP calculation: According to the operating conditions and fuel mode, find the MAP of the corresponding parameters such as fuel injection volume and air injection volume, and perform linear interpolation to calculate parameters such as air injection volume and fuel injection volume. MAP is a two-dimensional number table, the abscissa is the speed, and the ordinate is the load. MAP is the result of comprehensive optimization of all working conditions based on the Lagrange-SUMT optimization algorithm based on a large number of matching experiments.

Correction of control quantity: According to the calibration curve of the injection valve, calculate the injection pulse width, and correct it with air temperature, pressure, natural gas pressure and temperature. According to the characteristic curve of the oil pump, the displacement of the rack is calculated as the setting value of the closed-loop control of the rack.

Timing calculation: We set the injection end time at 110 degrees after the top dead center, and calculate the injection start point parameters according to the injection pulse width and engine speed, so as to ensure that the injection ends at a certain angle before the intake valve closes, avoiding short-scavenging High HC emissions and high fuel consumption rate caused by the road.

Communication management: Interpret the control commands and data sent by the peripherals, and provide the data to be sent to the send buffer.

The present invention utilizes software to control various situations of the engine:

Figure 11 shows the control strategy adopted by the present invention for starting the engine: the present invention considers that it is difficult to fully burn natural gas when starting, starts with diesel, and determines the fuel injection timing and fuel supply according to the rotational speed to achieve the purpose of reducing smoke. The specific measures are as follows: in the speed range lower than 200 rpm, control not to inject oil, after the speed is higher than this speed, start to supply a relatively small amount of oil, the amount of oil is calibrated based on a specific environment, and then consider Influenced by factors such as the working environment and the working state of the engine itself (whether it is a cold start or a hot start), the oil quantity is automatically corrected, and the correction formula is: Mo=Mb+F(Te, Tw)+Mu, where Mo is the actual supply Oil volume, Mb is the minimum starting oil volume at the calibration point, F is a function, Te is the ambient temperature, Tw is the cooling water temperature, and Mu is the unexpected correction value. If a start is not successful, the value will be automatically increased. The exact function of F is difficult to determine, so a simple linear correction is used. After the rotating speed is greater than 400 rev/min, transfer to normal rack control. The speed selection of 400 r/min is derived from experiments. If the speed is too high, the starting time is too long, and if it is too low, the effect of smoke restriction is not good. See Figure 5 for the block diagram of the starting procedure. Through this measure, the engine does not emit black smoke or white smoke when starting (cold start), and the starting performance is very good.

In terms of idling speed control, the present invention adopts a two-system speed governor. The speed regulating spring will automatically adjust the fuel injection quantity at idle speed. The control program only needs to adjust the speed regulating handle to a certain position according to the need. The adjustment method is a simple PID algorithm. In the actual vehicle test, we can adjust the idle speed arbitrarily according to the road conditions and the driver's feeling, and it is very convenient to find the best idle speed.

Figure 12 is a schematic diagram of the dual fuel workflow. Under normal operating conditions, it works in dual-fuel mode. In case of accidents such as insufficient gas volume, it can also switch to 100% pure diesel operating mode. This is also an advantage of dual-fuel vehicles. Fuel mode is controlled by a selector switch. The operating condition flow chart is shown in Figure 5: Calculate the number of working cylinders, air volume and oil volume according to the speed and load look-up table, then make λ optimization judgment, make necessary corrections to obtain the actual control value, and then determine the injection by the wheel cylinder strategy number of cylinders.

Fig. 13 is the cylinder deactivation strategy of the present invention. When the supercharged engine is at partial load, the air volume is much more than the air volume required for theoretical combustion, and the excess air coefficient is too large, resulting in high emissions and poor fuel economy. In order to make the engine work optimally at part load? Working nearby, adopt cylinder deactivation technology. That is to maintain the diesel supply to each cylinder, and stop injecting natural gas to some cylinders. Make the working cylinder work under the condition of optimized excess air coefficient. Because the port sequential injection system of this research program can control the natural gas injection of each cylinder regularly and quantitatively. Therefore, as long as the natural gas injection pulse width is set to zero, the "number of deactivated cylinders" stipulated by the control MAP can be accurately executed at any time, and the "deactivated cylinders" of the specified cylinders can be realized. In addition, in order to avoid the non-uniformity of the working intensity of each cylinder caused by the "deactivation of cylinders" measure, the "random method" deactivation strategy of cylinders is adopted. The basic idea is that after the engine has been working for a certain period of time with a certain number of cylinders under a working condition, the number of cylinders used for work is rotated according to a preset random rule so that the working time of each cylinder remains roughly the same. The so-called "random method" is not completely random, but "controllable random method". After working for a certain cycle, the number of working cycles is determined by experiments. The engine may be unstable due to the speed fluctuation caused by the wheel cylinder, and the time should not be too long, which will lose the meaning of the wheel cylinder. The implementation of the wheel cylinder algorithm is judged by an array of ccds. Taking one cylinder as an example, its work flow chart is shown in Figure 13, and the judgment flag is ccd.

Figures 14 and 15 are the oil volume self-calibration strategies of the present invention. Due to the deviation caused by the installation of the rack and the vibration of the engine, it will cause the rack-oil volume mismatch, which will affect the power, excess air coefficient optimization, emissions, etc. If the oil volume is too small, it will cause knocking , Lost fire and other abnormal combustion, so calibration correction is required. The principle of calibration is that when the engine (take the Styre diesel engine as an example) is running at 1000 r/min with no load, the required oil volume value is certain, so the corresponding rack position is also accurate. Based on this, the correct control rack MAP benchmark. The correction time should be as short as possible, the adjustment process should be smooth, and the result should be reliable. Calibration is a nested PID adjustment process. The target speed is set at 1000 rpm, and the speed is adjusted by adjusting the position of the rack to change the fuel supply.

Fig. 16 is a schematic diagram of real-time online correction of excess air coefficient. During the actual operation of the engine, the state of the external atmosphere and natural gas may be different from the experimental conditions, which will cause the excess air coefficient (λ) to deviate from the optimal 1548 specified by MAP; The diesel injection quantity is corrected in real time. As shown in Figure 6, the ECU collects the state parameters (temperature, pressure) of the natural gas and the air in the intake pipe in real time, calculates the natural gas and intake air density at that time, and then calculates the excessive amount based on the natural gas injection amount and the number of deactivated cylinders retrieved from the control MAP Air factor (λ). If the current λ is within the working range (λ rich limit<λ<λ lean limit), adjust the diesel/natural gas ratio so that |λ-λoptimal|≤(λoptimal: the optimal excess air ratio stored in MAP, σ : allowable excess air coefficient deviation); if the λ at that time exceeds the working range (λ rich limit > λ or λ > λ lean limit), the number of deactivated cylinders will be corrected (the number of deactivated cylinders is zero or 6, directly carry out diesel/ natural gas ratio adjustment). Finally, the engine is controlled according to the corrected number of deactivated cylinders, natural gas injection quantity, and diesel injection quantity.

Fig. 17 is a flow chart of cylinder number correction. After the cylinder deactivation method is adopted, if no measures are taken, it will inevitably cause the unevenness of the working intensity of each cylinder of the engine and reduce the working life of the engine. For this reason, a software algorithm based on "controllable random numbers" is designed in the program to realize the work of the wheel cylinder. However, if the cylinders work unevenly, it will cause fluctuations in the speed of the wheel cylinders. Correcting the unevenness of the injection valve can reduce this fluctuation.

When determining the number of working cylinders, first determine the number of working cylinders through the look-up table method and according to the "rounding" principle. However, if it is only determined according to the cylinder deactivation MAP, when the engine speed or load changes slightly, it may cause frequent changes in the number of cylinders at the critical point, seriously affecting the stability and reliability of the engine. Therefore, in addition to the need to reasonably design the MAP of the number of deactivated cylinders to ensure a certain overlapping area, it is also necessary to use the "threshold value method" to set the injection volume to ensure that the number of working cylinders will either remain unchanged, or the number of cylinders cannot be changed back immediately after being changed. The so-called "threshold value method" means that when the number of working cylinders needs to be changed by looking up the table, only when the change of the natural gas injection quantity is greater than the preset threshold value (threshold value) and lasts for a certain period of time is the change considered effective. The threshold value needs to be determined through experiments. It should not be too large or too small. If it is too large, it will affect the responsiveness of the engine. If it is too small, it will not work. In the program design, due to the different number of cylinders in each working condition, the "variable threshold value method" is adopted, and the experiment shows that the excess air ratio of natural gas/air is 3.5, which is more appropriate. The program block diagram is shown in Figure 17.

Figure 18 shows the speed fluctuations during the conversion from 1 cylinder to 6 cylinders at 1400 rpm and 2200 rpm. It can be seen that the fluctuation of the engine is very small during the conversion of the number of working cylinders. The speed fluctuation range at 2200 rpm is slightly larger than that at 1400 rpm, but the fluctuation range is less than 1%, which is acceptable. It can also be seen from the figure that the transition from 1-cylinder to 2-cylinder is the largest of all fluctuations. This is because in this transition, if no measures are taken, the single cylinder gas volume will be very large in a certain area, so that the mixture will be too rich and cause knocking. Therefore, in the software, the maximum working air volume is limited, and the excess air volume is converted into oil volume to ensure power, so that the rack changes slightly during the transition from 1 cylinder to 2 cylinder, resulting in excessive fluctuations in speed , while in the transition process of the remaining cylinder numbers, the gas volume transition of a single cylinder is relatively smooth, and the rack transition is smooth.

Fig. 19 is a rotation speed fluctuation diagram when oil and gas are switched at 1400 rpm. Fig. 20 is a diagram of rotation speed fluctuation when oil and gas are switched at 2200 r/min. Experimental results show that when working with natural gas at low load, natural gas cannot be fully combusted, so we set 25% of the rated load as the critical load point, and only start injecting gas when it is higher than the critical point. Therefore, in the transition process from diesel to dual-fuel mode in dual-fuel mode, there is a rack change process, and the position of the rack needs to be adjusted to reduce the amount of fuel. If the rack positions of the two differ greatly, it will cause engine vibration , leading to fluctuations in the rotational speed. For the air supply control process, we use the control of the opening time of the solenoid valve to achieve sequential injection, the system responds quickly, and the problem of fuel supply lag is not obvious, so the fluctuation of the whole process is not very severe (the maximum fluctuation is 80 at 1400 rpm RPM, more obvious at 2200 RPM, up to 220 RPM). The control strategy adopted is as follows: for the adjustment process of the rack, a smooth transition can be achieved through simple first-order filtering; for the air supply process, the optimization of the excess air coefficient is not considered during the transition process, and when the air volume of the meter is checked to A certain value (for example, when the air volume of a single cylinder is 20mg/st, this value generally does not meet the optimal excess air coefficient), that is, start 1 cylinder to work, and then transition to the normal operation program. Before this value, the heat of the gas volume needs to be compensated to the oil by increasing the amount of diesel oil according to the calorific value. Conversely, the same strategy is adopted when transitioning from cylinder 1 to cylinder 0. Part a of Figure 18 and Figure 19 is the speed wave curve of the switching process at 1400 rpm and 2200 rpm respectively, and part b is the fluctuation after adopting the first-order filter. Respectively from 80 and 220 to 30 and 90 rpm, the control effect is obvious.

Claims (4)

1, a kind of port-sequence-injection, lean-burn, full electronic controlled diesel/natural gas dual-fuel engine, comprise former diesel engine, natural gas supply system, diesel oil supply system and electronic control unit (ECU), it is characterized in that: rock gas port-sequence-injection device is installed, proportion of installation electromagnet and set up electronic control system on Injection Pump at the suction port place of each cylinder of motor; The solenoid valve seat that described rock gas port-sequence-injection device is installed solenoid valve by the injection electromagnetic valve that is installed in each cylinder air inlet place and being used to is formed, on solenoid valve seat, increase the natural gas distribution pipe, guide gas spraying to intake valve by the natural gas distribution pipe; Described rock gas gas circuit is made up of gas cylinder, rock gas filter cleaner, rock gas reduction valve; Gas cylinder is connected with the rock gas filter cleaner, and the rock gas filter cleaner is connected with the rock gas reduction valve, and the rock gas reduction valve is connected on the rock gas common rail pipe by flexible pipe, and joins with rock gas port-sequence-injection device; Described electronic control system is made up of with the plurality of sensors that is connected with motor electronic control unit; The output terminal of sensor is connected with the input end of electronic control system, and the output terminal of electronic control system is connected with above-mentioned injection electromagnetic valve, proportion electro-magnet.

2, port-sequence-injection according to claim 1, lean-burn, full electronic controlled diesel/natural gas dual-fuel engine, it is characterized in that: above-mentioned electronic control unit (ECU) is selected the MC6833232 of Motorola bit microprocessor for use, comprises micro controller module, digital collection module, power drive and protection module, power module, communication module and demonstration and alarm module; Wherein micro controller module is made up of crystal oscillator, storage and the chip that resets, and they all are connected with the MC6833232 bit microprocessor; The digital collection module is made up of collection of simulant signal circuit, switching value signal acquisition circuit and pulse signal acquisition circuit, the collection of simulant signal circuit comprises eliminator, A/D analog-digital converter, the input end of eliminator is connected with sensor, output terminal is connected with the input end of A/D analog-digital converter, and the output terminal of A/D analog-digital converter is connected with the interface of MC6833232 bit microprocessor; The output terminal of the input termination enable switch of the low-pass filter in the switching value signal acquisition circuit, output terminal is connected with the input end of scmitt trigger circuit, the output terminal of scmitt trigger circuit is connected with the interface of MC6833232 bit microprocessor, the input end of the eliminator in the pulse signal acquisition circuit is connected with the output terminal of sensor, the output terminal of eliminator is connected with the input end of scmitt trigger circuit, the output terminal of scmitt trigger circuit is connected with the input end of monostable circuit, and the output terminal of monostable circuit is connected with the interface of MC6833232 bit microprocessor; Power drive and protection module are made up of power drive pipe TMOS and power grid drive chip IR2127, and the input end of power grid drive chip IR2127 is connected with the output terminal of solenoid valve and proportion electro-magnet respectively, and output terminal is connected with the power drive pipe; It is the voltage-dropping type PWM switch power that master chip constitutes that power module adopts with MAX727; Communication module adopts the MAX202 chip, and the input end of this chip is connected with the SCI interface of MC6833232 bit microprocessor, and output terminal is connected with PC; Demonstration and alarm module are made up of a triode that is connected with the MC6833232 bit microprocessor and connected tutorial light; Electronic throttle sensor in the sensor, be installed in natural gas temperature sensor, natural pressure force transducer on the rock gas common rail pipe, be installed in intake air temperature sensor and air inlet pressure sensor on the suction tude, be installed in cooling water temperature sensor, oil temperature sensor and oil pressure sensor in the engine body, be installed in the tooth bar feedback transducer on the proportion electro-magnet; The output terminal of these sensors all is connected with the input end of collection of simulant signal circuit in the electronic control system; The input end that is installed in the synchronous signal sensor on the engine cam and is installed in the pulse signal acquisition circuit in output terminal and the electronic control system of footmark sensor of engine flywheel dish top is connected.

3, the bottle mouth position of the rock gas gas cylinder in port-sequence-injection according to claim 1, lean-burn, the complete above-mentioned rock gas gas circuit of electronic controlled diesel/natural gas dual-fuel engine is equipped with rock gas hand off valve, at the pipeline place that is connected with the rock gas filter cleaner rock gas swift electron cut-off valve is housed.

4, the input end reverse parallel connection transient voltage of port-sequence-injection according to claim 1, lean-burn, the complete above-mentioned power module of electronic controlled diesel/natural gas dual-fuel engine suppresses diode TVP.

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