CN114837841A - Voltage-stabilizing switchable multi-stage fuel injection system and method - Google Patents
Voltage-stabilizing switchable multi-stage fuel injection system and method Download PDFInfo
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- CN114837841A CN114837841A CN202210629324.6A CN202210629324A CN114837841A CN 114837841 A CN114837841 A CN 114837841A CN 202210629324 A CN202210629324 A CN 202210629324A CN 114837841 A CN114837841 A CN 114837841A
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- 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
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/3809—Common rail control systems
- F02D41/3827—Common rail control systems for diesel engines
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- 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
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/3809—Common rail control systems
- F02D41/3836—Controlling the fuel pressure
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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
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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
- F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
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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
- F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
- F02M63/0012—Valves
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Fuel-Injection Apparatus (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
Abstract
The invention discloses a pressure-stabilizing switchable multi-stage fuel injection system and method. The high-pressure oil pump is used for pumping the oil pump in the oil tank into the high-pressure reserved cavity and the high-pressure common rail; the high-pressure common rail is used for providing high-pressure oil to the oil injector; the high-pressure reserved cavity is used for prestoring high-pressure oil, and introducing the high-pressure oil to the oil injector when multi-section injection is needed; the inlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity communicated with the high-pressure oil pump and the high-pressure common rail; the outlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity for communicating the high-pressure common rail and the oil injector; the oil injector is used for injecting high-pressure oil; and the engine control unit is used for acquiring vehicle parameters, determining injection parameters according to the vehicle parameters, and controlling the opening and closing of the inlet electromagnetic valve and the outlet electromagnetic valve according to the injection parameters to perform multi-section fuel injection control. The fuel injection device ensures that the fuel injection duration is shortened and the fuel combustion efficiency is improved through the pressure storage function of the high-pressure reserved cavity.
Description
Technical Field
The invention belongs to the technical field of automobile engine control, and particularly relates to a pressure-stabilizing switchable multi-stage fuel injection system and method.
Background
The high pressure common rail system adopts a common rail pipe between a high pressure oil pump and an oil injector to accumulate fuel oil output by the high pressure oil pump and inhibit pressure fluctuation, and then the fuel oil is conveyed to each oil injector through each high pressure oil pipe. The action of the solenoid valve on the injector controls the start and the end of injection, the moment when the solenoid valve acts determines the injection timing, and the duration of the action and the common rail pressure together determine the injection quantity.
The pilot injection 1 is prior to the main injection, and the result of the pilot injection is that the pressure of mixed gas in the cylinder is slightly increased; the delay in the main injection combustion process is shortened; the combustion pressure peak is reduced. Eventually, the combustion is softened, thereby reducing combustion noise.
The adoption of 2 times of pre-injection can reduce the single injection oil quantity, thereby inhibiting the penetration distance of the injection oil column and effectively reducing the chance of the fuel oil colliding the wall.
And the target total fuel injection amount in the fuel system is converted from the engine torque. Meanwhile, the target total fuel injection quantity (calculated by mass) of each cylinder in each cycle is determined by the engine demand torque according to a fuel quantity/torque conversion curve through an interpolation method.
The prior art needs to control accurate communication of pre-injection, main injection and post-injection, at the present stage, in the fuel injection process of a diesel engine, the fuel injection of the diesel engine is divided into pre-injection, main injection and post-injection, each injection only acts once, continuity and continuity do not exist, the fuel injection is controlled according to the power-on time of a normally closed electromagnetic valve in each injection, but the pressure of an oil rail is gradually reduced along with the injection, so that the fuel system has high requirements on rail pressure, but a high-pressure oil path can cause head loss when fuel fluid is injected into a cylinder due to the opening of the normally closed electromagnetic valve, the rail pressure is reduced in the single injection time sequence process, the difference between the actual fuel injection quantity and the expected fuel injection quantity exists, the injection duration is prolonged, and the combustion cannot be well controlled.
Disclosure of Invention
The present invention is directed to solve the above-mentioned drawbacks of the prior art, and provides a simple, high combustion efficiency, and stable pressure switchable multi-stage fuel injection system and method.
The technical scheme adopted by the invention is as follows: a pressure-stabilizing switchable multi-stage fuel injection system comprises
The high-pressure oil pump is used for pumping the oil pump in the oil tank into the high-pressure reserved cavity and the high-pressure common rail;
the high-pressure common rail is used for providing high-pressure oil to the oil injector;
the high-pressure reservation cavity is used for prestoring high-pressure oil, and introducing the high-pressure oil to the oil injector when multi-section injection is needed;
the inlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity communicated with the high-pressure oil pump and the high-pressure common rail;
the outlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity for communicating the high-pressure common rail and the oil injector;
the oil injector is used for injecting high-pressure oil;
and the engine control unit is used for acquiring vehicle parameters, determining injection parameters according to the vehicle parameters, and controlling the opening and closing of the inlet electromagnetic valve and the outlet electromagnetic valve according to the injection parameters to perform multi-section fuel injection control.
A method for realizing voltage-stabilizing switchable multi-segment fuel injection based on the voltage-stabilizing switchable multi-segment fuel injection system comprises the following steps:
And (5) controlling the outlet electromagnetic valve to be closed, building pressure for the high-pressure reserved cavity after the pressure building condition is met, and returning to the step 1.
Further, the determination process of the injection parameters is as follows:
determining a target total oil quantity according to the torque demand of the engine and the rotating speed of the engine, and distributing the target total oil quantity to obtain a pre-injection 1 oil quantity and a main injection oil quantity;
converting the pre-injection 1 oil quantity and the main injection oil quantity into a pre-injection 1 volume quantity and a main injection volume quantity;
determining the estimated action time of the pilot injection 1 and the estimated action time of the main injection according to the volume amount of the pilot injection 1 and the volume amount of the main injection;
and calculating the injection frequency of the pilot injection 1, the injection frequency of the main injection, the power-on duration of the pilot injection 1, the injection interval of the pilot injection 1 and the injection interval of the main injection according to the estimated action time of the pilot injection 1, the estimated action time of the main injection, the injection advance angle of the pilot injection 1, the injection advance angle of the main injection, the engine speed and the accelerator change rate.
Further, the high-pressure reserve chamber pressure p1 at the present time is determined by the following formula:
p1 is Pmax-delta P1, Pmax is the pressure of the pressure build-up ending moment of the high pressure reserve cavity or the pressure of the high pressure reserve cavity at the starting moment of the multi-segment fuel injection in the previous period, and delta P1 is the pressure attenuation amount of the high pressure reserve cavity in the multi-segment fuel injection in the previous period.
Further, the delta P1 is obtained by checking a P1-t 1-attenuation delta P MAP table, wherein P1 is the high-pressure common-rail pressure at the current moment, and t1 is the opening time of the outlet electromagnetic valve in the multi-stage fuel injection process of the current period.
Further, the opening time t1 of the outlet solenoid valve is determined by the following equation:
t1 is pilot injection 1 energization time + main injection energization time + pilot injection 1 injection interval + number of pilot injection 1 injections + number of main injection intervals + number of main injection injections.
Further, it is determined that the pressure build-up condition is satisfied when the engine is in a normal operation and in a high load state; the high load state means that the rotating speed of the engine is in a set range and the torque percentage reaches more than 85 percent.
Further, the step of building the pressure of the high-pressure reserved cavity means that an inlet electromagnetic valve is opened, high-pressure oil is injected into the high-pressure reserved cavity through a high-pressure oil pump and a high-pressure common rail, the pressure in the high-pressure reserved cavity is increased until set conditions are met, the inlet electromagnetic valve is controlled to be closed, and the pressure building of the high-pressure reserved cavity is finished.
Further, the set conditions are that T1 is not less than or equal to min (T2, T3), where min () represents taking the minimum value, T1 is the accumulated pressure buildup time from the pressure buildup starting time, T2 is the theoretical pressure buildup time corresponding to the engine speed at the pressure buildup starting time, and T3 is the theoretical pressure buildup time corresponding to the real-time engine speed during the pressure buildup process.
Furthermore, the pressure at the pressure building ending moment of the high-pressure reserve cavity is equal to the pressure of the high-pressure common rail at the moment, and the pressure of the high-pressure common rail is detected by the common rail sensor.
The invention has the beneficial effects that:
according to the invention, the high-pressure reserved cavity and the corresponding electromagnetic valve are added among the high-pressure oil pump, the high-pressure common rail and the oil injector, and the high pressure of the oil rail of the engine in a high-pressure state can be kept in the high-pressure reserved cavity and the electromagnetic valve through control on the high-pressure reserved cavity and the electromagnetic valve; meanwhile, when the engine oil sprayer performs multi-stage injection, due to the fact that partial pressure in the high-pressure oil rail is removed, the injection wire harness formed during the injection of the engine oil sprayer is gradually attenuated, and at the moment, pre-stored high-pressure oil can be guided into the common rail through the high-pressure reserved cavity to maintain the pressure of the high-pressure common rail in the injection process, so that the stability of the injection wire harness of the engine oil sprayer is kept, and the combustion efficiency in an engine cylinder body of the engine oil sprayer is better improved; and because the pressure of the high-pressure rail pressure is stable, the injection performance of the oil injector is stable, the running stability of the engine is further ensured, and the bad conditions of knocking and the like caused by uneven injection are reduced.
According to the invention, through the pressure storage function of the high-pressure reserved cavity, the outlet electromagnetic valve can be opened during the injection interval, and the high-pressure oil in the high-pressure oil rail cavity is introduced into the common rail, so that the oil pressure reduced by the injection is rapidly increased, the fuel injection duration is ensured to be shortened, and the fuel combustion efficiency is improved. The invention can also enlarge the volume of high-pressure oil in the fuel system of the engine based on the capability of storing high pressure by the high-pressure reserved cavity, thereby reducing the oil pressure fluctuation in the high-pressure oil pipe of the engine when the oil injector injects, reducing the error of single injection oil quantity, and ensuring the stability of multiple injection oil quantity
Drawings
Fig. 1 is a schematic diagram of a pressure-stabilizing switchable multi-stage fuel injection system according to the present invention.
FIG. 2 is a flow chart of the pressure-stabilizing switchable multi-stage fuel injection method of the present invention.
FIG. 3 is a schematic diagram illustrating the operation of the voltage-stabilizing switchable multi-stage fuel injection method according to the present invention.
In the figure, 1-high pressure oil pump; 2-fuel oil filter; 3-an oil tank; 4-high pressure common rail; 5-a common rail sensor; 6-an engine control unit; 7-high pressure reserve cavity; 8-inlet solenoid valve; 9-outlet solenoid valve; 10-oil sprayer.
Detailed Description
The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Where the terms "comprising", "having" and "including" are used in this specification, there may be another part or parts unless otherwise stated, and the terms used may generally be in the singular but may also be in the plural.
The features of the various embodiments of the present invention may be partially or fully combined or spliced with each other and performed in a variety of different configurations as would be well understood by those skilled in the art. Embodiments of the invention may be performed independently of each other or may be performed together in an interdependent relationship.
As shown in fig. 1, the present invention provides a pressure-stabilizing switchable multi-stage fuel injection system, which includes a high-pressure oil pump 1 for pumping fuel into a high-pressure reserve chamber 7 and a high-pressure common rail 4;
the fuel filter 2 is used for filtering the fuel in the fuel tank 1 and outputting the filtered fuel to the high-pressure oil pump 1;
a high pressure common rail 4 for supplying high pressure oil to the injector 10;
a common rail sensor 5 is arranged on the high-pressure common rail 4 and used for detecting the pressure of the high-pressure common rail;
one end of the high-pressure reserved cavity 7 is communicated with inlets of the high-pressure oil pump 1 and the high-pressure common rail 4 through pipelines, and the other end of the high-pressure reserved cavity is communicated with an outlet of the high-pressure common rail 4 and an inlet of the oil injector 10 through pipelines and is used for prestoring high-pressure oil which is led into the oil injector when multi-stage injection is needed;
the inlet electromagnetic valve 8 is arranged on a common pipeline of the high-pressure reserve cavity 7 for communicating the high-pressure oil pump 1 and the high-pressure common rail 4, namely when the inlet electromagnetic valve 8 is closed, the high-pressure reserve cavity 7 is disconnected with channels between the high-pressure oil pump 1 and the high-pressure common rail 4;
the outlet electromagnetic valve 9 is arranged on a common pipeline of the high-pressure reserve cavity 7 for communicating the high-pressure common rail 4 and the oil injector 10, namely when the outlet electromagnetic valve 9 is closed, the high-pressure reserve cavity 7 is disconnected with channels between the high-pressure common rail 4 and the oil injector 10;
an oil injector 10 for injecting high-pressure oil;
and the engine control unit (EECU)6 is used for collecting vehicle parameters, determining injection parameters according to the vehicle parameters, controlling the opening and closing of the inlet electromagnetic valve 8 and the outlet electromagnetic valve 9 according to the injection parameters and carrying out multi-stage fuel injection control.
The invention also provides a method for realizing the voltage-stabilizing switchable multi-stage fuel injection based on the voltage-stabilizing switchable multi-stage fuel injection system, as shown in fig. 2 and 3, the method comprises the following steps:
and 3, if P1 is not more than P1, or the injection frequency of the pilot injection 1 is 1 and the injection frequency of the main injection is 1 (namely the pressure is not met, or the frequency of the pilot injection 1 and the frequency of the main injection are both equal to 1), controlling the outlet electromagnetic valve to be closed, building pressure for the high-pressure reserve cavity after the pressure building condition is met, and returning to the step 1.
In the above scheme, the determining process of the injection parameter is as follows:
1. the target total oil amount is determined according to the engine torque demand and the engine revolution number based on the MAP table 1 as follows.
TABLE 1 Engine Torque request vs. Engine revolutions MAP Table
| |
Engine requested |
Engine required |
Engine requested |
|
| Rotational speed A | Target total oil amount 11 | Target total oil amount 12 | Target total oil amount 13 | Target total oil amount 14 |
| Rotational speed B | .... | ... | ... | ... |
| Rotational speed C | ... | ... | ... | ... |
| Rotational speed D | ... | ... | ... | ... |
2. Distributing the target total oil quantity and the current engine rotating speed according to a two-dimensional table look-up to obtain a pre-injection 1 oil quantity and a main injection oil quantity;
3. converting the pre-injection 1 oil quantity and the main injection oil quantity into a pre-injection 1 volume quantity and a main injection volume quantity: in order to accurately control the amount of fuel in consideration of the influence of the fuel temperature on the fuel density ρ, the mass-injected fuel quantity Q injected per cylinder per cycle is calculated m Further converted into a volume Q v :
Q v ＝Q m /ρ (tF)
tF Is the fuel temperature; rho (tF) Is composed of tF The density of the fuel.
4. And searching and determining the estimated acting time of the pre-injection 1/main injection according to a two-dimensional table between the volume amount of the pre-injection 1 and the volume amount of the main injection and the rail pressure.
5. Calculating the injection frequency of the pilot injection 1, the injection frequency of the main injection, the power-on duration of the pilot injection 1, the injection interval of the pilot injection 1 and the injection interval of the main injection according to the estimated action time of the pilot injection 1, the estimated action time of the main injection, the injection advance angle of the pilot injection 1, the injection advance angle of the main injection, the engine speed and the throttle change rate:
when calculating the main injection times, the (pilot injection 1/main injection) injection times need to be obtained according to the (pilot injection/main injection) estimated action time and the pilot injection advance angle lookup table 2.
TABLE 2 estimated action time and Pre-injection Advance Angle MAP Table
The (pilot 1/main injection) energization time is obtained by dividing the estimated action time by the number of injections, and is expressed as follows:
(pilot injection 1/main injection) power-up time ═ estimated action time/(pilot injection 1/main injection) number of injections
When the number of (pilot 1/main injection) injections is equal to 1, the injection interval of (pilot 1/main injection) is 0 (i.e., an invalid value), and when the number of (pilot 1/main injection) injections is greater than 1, the injection interval of (pilot 1/main injection) will be obtained by the engine speed and throttle change rate lookup table 3.
TABLE 3 Engine speed and throttle Rate of Change, injection Interval MAP Table
The process of multi-cycle multi-stage injection is described in detail below starting from the moment when the high-pressure reserve chamber starts to build pressure:
1) and when the engine runs normally and is in a high-load state, controlling to open the inlet electromagnetic valve, starting to build pressure in the high-pressure reserved cavity, closing the inlet electromagnetic valve after the pressure building time is up, finishing the pressure building in the high-pressure reserved cavity, and recording the maximum pressure Pmax of the high-pressure reserved cavity at the moment.
The normal operation refers to that the fuel oil system of the engine can normally inject oil based on the opening degree of the accelerator stepped by the driver, and the air system of the engine can normally absorb air so as to facilitate the normal fuel oil of the fuel oil and the air in the cylinder of the engine and provide the torque required by the whole vehicle; the high load state means that the rotating speed of the engine is in a set range and the torque percentage reaches more than 85 percent.
The step of building pressure of the high-pressure reserved cavity refers to opening an inlet electromagnetic valve, injecting high-pressure oil into the high-pressure reserved cavity through a high-pressure oil pump and a high-pressure common rail, improving the pressure in the high-pressure reserved cavity, controlling to close the inlet electromagnetic valve until set conditions are met, and finishing building pressure of the high-pressure reserved cavity.
The set conditions are that T1 is not less than min (T2, T3), wherein min () represents that the minimum value is taken from T2 and T3, T1 is accumulated pressure buildup time (namely opening time of an inlet electromagnetic valve) from the pressure buildup starting moment, T2 is theoretical pressure buildup time corresponding to the engine speed at the pressure buildup starting moment, T3 is theoretical pressure buildup time corresponding to the real-time engine speed in the pressure buildup process, and T2 and T3 are obtained by checking an engine speed and theoretical pressure buildup time MAP table.
And the pressure Pmax at the pressure build-up finishing moment of the high-pressure reserve cavity is equal to the pressure of the high-pressure common rail at the moment, and the pressure of the high-pressure common rail is detected by a common rail sensor.
2) And after the pressure build-up of the high-pressure reserved cavity is finished, when the first period multi-section fuel injection is started, controlling to open the outlet electromagnetic valve, injecting high-pressure oil into the high-pressure common rail by the high-pressure reserved cavity, calculating the opening time t1 of the outlet electromagnetic valve, controlling to close the outlet electromagnetic valve after the opening time is reached, finishing the first period multi-section fuel injection, determining the pressure P1 of the high-pressure common rail and the pressure P1 of the high-pressure reserved cavity at the moment, and entering the step 3).
The high-pressure common rail pressure P1 is detected by a rail pressure sensor. After the previous cycle multi-stage fuel injection is completed, the attenuation amount Δ P of the pressure in the high-pressure reserve cavity needs to be calculated, when the next cycle multi-stage fuel injection is started, the pressure P of the high-pressure reserve cavity (that is, the pressure of the high-pressure reserve cavity when the current cycle multi-stage fuel injection is completed) is P ═ Pmax- Δ P, wherein Δ P is obtained by checking a P-outlet solenoid valve opening time t 1-attenuation amount MAP table, and then the pressure P1 of the high-pressure reserve cavity is P1 ═ Pmax- Δ P1.
The opening time t1 of the outlet solenoid valve is as follows: t1 is pilot injection 1 energization time + main injection energization time + pilot injection 1 injection interval + number of pilot injection 1 injections + number of main injection intervals + number of main injection injections. The pre-spraying 1/main spraying parameters in the formula are all parameters determined in the first period.
3) And when the multi-stage fuel injection in the second period starts, if P1 is larger than P1 and the pilot injection 1/main injection times are larger than 1, controlling to open the outlet electromagnetic valve, injecting high-pressure oil into the high-pressure common rail by the high-pressure reserve cavity, calculating the opening time t2 of the outlet electromagnetic valve, controlling to close the outlet electromagnetic valve after the opening time is reached, ending the multi-stage fuel injection in the second time, determining the pressure P2 of the high-pressure common rail and the pressure P2 of the high-pressure reserve cavity, wherein P2 is P1-delta P2, and obtaining the delta P2 by checking a P2-opening time t 2-attenuation table of the outlet electromagnetic valve. The opening time t2 of the outlet solenoid valve is as follows: t2 is pilot injection 1 energization time + main injection energization time + pilot injection 1 injection interval + number of pilot injection 1 injections + number of main injection intervals + number of main injection injections. The pre-injection 1/main injection parameters in the formula are all parameters determined by the second period.
4) And repeating the process of the step 3 until the fuel injection of the fuel injection section of the nth period starts, if Pn is less than or equal to Pn, the reserved cavity does not inject pressure any more, waiting for the next pressure building, and returning to the step 1).
When fuel oil is injected in the oil injection section of each period, the number of times of pilot injection 1/main injection is required to be considered, because when the number of times of pilot injection 1/main injection is equal to 1, only one section of injection is carried out, and the multi-section injection function is closed; when at least one injection frequency in the pilot injection 1/main injection is more than 1, the multi-stage injection is indicated.
The opening time of the outlet electromagnetic valve is longer than the total time from the start of the fuel injector to the close of the fuel injector in the pre-injection 1/main injection stage.
It should be understood that the specific order or hierarchy of steps in the processes disclosed is an example of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged without departing from the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented.
The foregoing is considered as illustrative of the preferred embodiments of the invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims. Those not described in detail in this specification are within the skill of the art.
Claims (10)
1. A switchable multistage fuel injection system of steady voltage which characterized in that: comprises that
The high-pressure oil pump is used for pumping the oil pump in the oil tank into the high-pressure reserved cavity and the high-pressure common rail;
the high-pressure common rail is used for providing high-pressure oil to the oil injector;
one end of the high-pressure reserved cavity is communicated with the high-pressure oil pump and the high-pressure common rail inlet through a pipeline, and the other end of the high-pressure reserved cavity is communicated with the high-pressure common rail outlet and the injector inlet through a pipeline, so that high-pressure oil is prestored and is guided to the injector when multi-stage injection is required;
the inlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity communicated with the high-pressure oil pump and the high-pressure common rail;
the outlet electromagnetic valve is arranged on a common pipeline of the high-pressure reserved cavity for communicating the high-pressure common rail and the oil injector;
the oil injector is used for injecting high-pressure oil;
and the engine control unit is used for acquiring vehicle parameters, determining injection parameters according to the vehicle parameters, and controlling the opening and closing of the inlet electromagnetic valve and the outlet electromagnetic valve according to the injection parameters to perform multi-section fuel injection control.
2. A method for realizing the voltage-stabilizing switchable multi-stage fuel injection based on the voltage-stabilizing switchable multi-stage fuel injection system of claim 1, characterized in that:
step 1, performing multi-segment fuel injection control of a current period according to injection parameters, and judging the sizes of high-pressure common rail pressure P1 and high-pressure reserve cavity pressure P1, the number of pilot injection 1 injections and the number of main injection injections at the current moment when the multi-segment fuel injection of the current period starts;
step 2, if P1 is larger than P1, the injection frequency of the pilot injection 1 is larger than 1 and/or the injection frequency of the main injection is larger than 1, controlling to open the outlet electromagnetic valve, injecting high-pressure oil into the high-pressure common rail by the high-pressure reserve cavity, calculating the opening time of the outlet electromagnetic valve, controlling to close the outlet electromagnetic valve after the opening time is reached, ending the multi-section fuel injection in the current period, determining the high-pressure common rail pressure P2 and the high-pressure reserve cavity pressure P2 at the ending moment, waiting for the multi-section fuel injection in the next period, and returning to the step 1;
and 3, if P1 is not more than P1, or the injection frequency of the pilot injection 1 is 1 and the injection frequency of the main injection is 1, controlling the outlet electromagnetic valve to be kept closed, building pressure for the high-pressure reserve cavity after the pressure building condition is met, and returning to the step 1.
3. The pressure-stabilizing switchable multi-stage fuel injection method according to claim 2, characterized in that: the injection parameter determination process comprises the following steps:
determining a target total oil quantity according to the torque demand of the engine and the rotating speed of the engine, and distributing the target total oil quantity to obtain a pre-injection 1 oil quantity and a main injection oil quantity;
converting the pre-injection 1 oil quantity and the main injection oil quantity into a pre-injection 1 volume quantity and a main injection volume quantity;
determining the estimated action time of the pilot injection 1 and the estimated action time of the main injection according to the volume amount of the pilot injection 1 and the volume amount of the main injection;
and calculating the injection frequency of the pilot injection 1, the injection frequency of the main injection, the power-on duration of the pilot injection 1, the injection interval of the pilot injection 1 and the injection interval of the main injection according to the estimated action time of the pilot injection 1, the estimated action time of the main injection, the injection advance angle of the pilot injection 1, the injection advance angle of the main injection, the engine speed and the accelerator change rate.
4. The pressure-stabilizing switchable multi-stage fuel injection method according to claim 2, characterized in that: the high-pressure reserve chamber pressure p1 at the present moment is determined by the following formula:
p1 is Pmax-delta P1, Pmax is the pressure of the pressure build-up ending moment of the high pressure reserve cavity or the pressure of the high pressure reserve cavity at the starting moment of the multi-segment fuel injection in the previous period, and delta P1 is the pressure attenuation amount of the high pressure reserve cavity in the multi-segment fuel injection in the previous period.
5. The steady-pressure switchable multi-stage fuel injection method according to claim 4, characterized in that: the delta P1 is obtained by checking a P1-t 1-attenuation delta P MAP table, P1 is the high-pressure common rail pressure at the current moment, and t1 is the opening time of the outlet electromagnetic valve in the multi-stage fuel injection process of the current period.
6. The steady-pressure switchable multi-stage fuel injection method according to claim 5, characterized in that: the opening time t1 of the outlet solenoid valve is determined by the following equation:
t1 is pilot injection 1 energization time + main injection energization time + pilot injection 1 injection interval + number of pilot injection 1 injections + number of main injection intervals + number of main injection injections.
7. The pressure-stabilizing switchable multi-stage fuel injection method according to claim 2, characterized in that: and determining that the pressure building condition is met when the engine is in normal operation and in a high-load state, wherein the high-load state means that the rotating speed of the engine is in a set range and the torque percentage reaches more than 85%.
8. The steady-pressure switchable multi-stage fuel injection method according to claim 7, characterized in that: the step of building pressure of the high-pressure reserved cavity refers to opening an inlet electromagnetic valve, injecting high-pressure oil into the high-pressure reserved cavity through a high-pressure oil pump and a high-pressure common rail, improving the pressure in the high-pressure reserved cavity, controlling to close the inlet electromagnetic valve until set conditions are met, and finishing building pressure of the high-pressure reserved cavity.
9. The steady-pressure switchable multi-stage fuel injection method according to claim 8, characterized in that: the set conditions are that T1 is not less than min (T2, T3), wherein min () represents the minimum value, T1 is the accumulated pressure buildup time from the pressure buildup starting moment, T2 is the theoretical pressure buildup time corresponding to the engine rotating speed at the pressure buildup starting moment, and T3 is the theoretical pressure buildup time corresponding to the real-time rotating speed of the engine in the pressure buildup process.
10. The steady-pressure switchable multi-stage fuel injection method according to claim 8, characterized in that: the pressure at the pressure building ending moment of the high-pressure reserve cavity is equal to the pressure of the high-pressure common rail at the moment, and the pressure of the high-pressure common rail is detected by the common rail sensor.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08277762A (en) * | 1996-04-10 | 1996-10-22 | Mitsubishi Motors Corp | Accumulator type fuel injection system |
| US20030111055A1 (en) * | 2001-12-14 | 2003-06-19 | Siemens Automotive Corporation | Corrugated fuel rail damper |
| CN102364079A (en) * | 2011-11-21 | 2012-02-29 | 哈尔滨工程大学 | Multistage pressure accumulating and graded supercharging configurable fuel injection system of diesel engine |
| CN112267964A (en) * | 2020-11-16 | 2021-01-26 | 天津职业技术师范大学(中国职业培训指导教师进修中心) | Sectional rail for high-pressure common rail system and control method thereof |
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- 2022-05-31 CN CN202210629324.6A patent/CN114837841B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08277762A (en) * | 1996-04-10 | 1996-10-22 | Mitsubishi Motors Corp | Accumulator type fuel injection system |
| US20030111055A1 (en) * | 2001-12-14 | 2003-06-19 | Siemens Automotive Corporation | Corrugated fuel rail damper |
| CN102364079A (en) * | 2011-11-21 | 2012-02-29 | 哈尔滨工程大学 | Multistage pressure accumulating and graded supercharging configurable fuel injection system of diesel engine |
| CN112267964A (en) * | 2020-11-16 | 2021-01-26 | 天津职业技术师范大学(中国职业培训指导教师进修中心) | Sectional rail for high-pressure common rail system and control method thereof |
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