CN117287324A - Control system and method suitable for rail pressure substitution value of high-pressure common rail system of diesel engine - Google Patents
Control system and method suitable for rail pressure substitution value of high-pressure common rail system of diesel engine Download PDFInfo
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- CN117287324A CN117287324A CN202311050541.0A CN202311050541A CN117287324A CN 117287324 A CN117287324 A CN 117287324A CN 202311050541 A CN202311050541 A CN 202311050541A CN 117287324 A CN117287324 A CN 117287324A
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- 238000006467 substitution reaction Methods 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000000446 fuel Substances 0.000 claims abstract description 144
- 239000003921 oil Substances 0.000 claims abstract description 140
- 239000000295 fuel oil Substances 0.000 claims abstract description 13
- 238000002347 injection Methods 0.000 claims description 20
- 239000007924 injection Substances 0.000 claims description 20
- 239000007788 liquid Substances 0.000 claims description 18
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 230000006835 compression Effects 0.000 claims description 11
- 238000007906 compression Methods 0.000 claims description 11
- 239000000872 buffer Substances 0.000 claims description 9
- 101100082008 Plasmodium falciparum (isolate 3D7) PFS230 gene Proteins 0.000 claims description 7
- 101100082009 Plasmodium falciparum (isolate NF54) PF230 gene Proteins 0.000 claims description 7
- 230000005856 abnormality Effects 0.000 claims description 4
- 238000002485 combustion reaction Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 claims description 3
- 230000002401 inhibitory effect Effects 0.000 claims 1
- 230000008859 change Effects 0.000 abstract description 9
- 230000002159 abnormal effect Effects 0.000 abstract description 3
- 230000001276 controlling effect Effects 0.000 description 11
- 230000009471 action Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000010420 art technique Methods 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
Classifications
-
- 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
- F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
- F02M55/02—Conduits between injection pumps and injectors, e.g. conduits between pump and common-rail or conduits between common-rail and injectors
- F02M55/025—Common rails
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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
-
- 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
- F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
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- Chemical & Material Sciences (AREA)
- 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 relates to a control system suitable for rail pressure substitution values of a high-pressure common rail system of a diesel engine, which comprises a hydraulic system and an electronic control system EDC; the hydraulic system comprises a high-pressure oil rail and a high-pressure oil pipe. The invention also relates to a control method suitable for the rail pressure substitution value of the high-pressure common rail system of the diesel engine, which comprises the following steps: calculating to obtain rail pressure control deviation; calculating to obtain the required fuel oil variation; calculating to obtain the required fuel flow; calculating to obtain the actual oil inlet amount and the actual oil outlet amount; and calculating to obtain an estimated rail pressure. The invention provides a solution when rail pressure is abnormal; and accurately estimating rail pressure change generated after the high-pressure oil pump and the electric control pressure relief valve act.
Description
Technical Field
The invention relates to the technical field of control of a high-pressure common rail fuel system of a diesel engine, in particular to a control system and a control method suitable for a rail pressure substitution value of the high-pressure common rail system of the diesel engine.
Background
As shown in fig. 1, the structure of the conventional high-pressure common rail fuel system is generally as follows: the low-pressure fuel is pumped out from the fuel tank by the low-pressure fuel pump, filtered by the fuel filter, pressurized by the high-pressure fuel pump and enters the fuel rail, and the fuel flow of the high-pressure fuel pump is controlled by the fuel metering unit.
The oil rail is provided with a rail pressure sensor and an electric control pressure regulating valve, the rail pressure sensor is used for measuring the pressure level in the oil rail and is used as a feedback signal for rail pressure closed-loop control, and when the rail pressure sensor fails, the system is required to provide a rail pressure substitution value for rail pressure closed-loop control; the electric control pressure regulating valve can drain oil quickly to reduce rail pressure, and is used for rail pressure control. The fuel injector is connected with the fuel rail through a high-pressure fuel pipe and is used for injecting required fuel quantity into the cylinder. The fuel metering unit MeUn, the electric control relief valve ePRV and the fuel injector are controlled by the electric control unit ECU.
Based on the high-pressure common rail fuel system structure, in the calculation of the alternative value of the rail pressure, the prior art scheme is a table look-up method, specifically: in the common technical scheme, when a rail pressure sensor fails, the rail pressure substitution value is obtained by using parameters such as the engine speed, the injected oil quantity and the like to look up a table.
The table look-up method in the prior art has the following defects:
the method for calculating the rail pressure substitution value by table lookup can only give a pre-calibrated and empirical substitution value and cannot be adjusted according to the actual working condition, so that the accuracy is low.
There are very few prior art techniques that employ other control strategies in order to cope with sensor failures; the most typical application is CN202110848457.8, the invention is Chinese patent application of 'high-pressure oil rail pressure control method and system after the air inlet phase sensor fails', which discloses the following technical scheme:
1. a high-pressure oil rail pressure control method after the failure of an air inlet phase sensor comprises the following steps: after the air inlet phase sensor fails, controlling the air inlet variable valve timing to return to a locking position; acquiring the current rotating speed of an air inlet cam shaft; acquiring a first closing time and a first opening time of a high-pressure oil pump control valve corresponding to a locking position at a current rotating speed; determining a target closing time according to the first closing time, and determining a target opening time according to the first opening time; acquiring target oil rail pressure according to the current rotating speed; controlling the actual rail pressure according to the target rail pressure in a time period from the target closing time to the target opening time; the high-pressure oil pump control valve is used for controlling the opening and closing of a low-pressure oil way.
2. Determining a target closing time according to the first closing time, and determining a target opening time according to the first opening time, including: the first closing time is set as a target closing time, and the first opening time is set as a target opening time.
3. After obtaining the current rotation speed of the intake camshaft, the method further comprises: acquiring a closing time set and an opening time set of a high-pressure oil pump control valve corresponding to the intake variable valve timing at any position at the current rotating speed; determining a target closing time according to the first closing time, and determining a target opening time according to the first opening time, including: the maximum time in the first closing time and closing time set is taken as a target closing time, and the minimum time in the first opening time and opening time set is taken as a target opening time.
4. Obtaining a target rail pressure according to the current rotational speed, including: acquiring an accelerator opening, and acquiring the current demand load of the engine according to the accelerator opening and the current rotating speed; and determining the target oil rail pressure according to the current demand load and the current rotating speed.
5. Determining a target rail pressure according to the current demand load and the current rotational speed, including: obtaining the limit load of the engine at the current rotating speed, and calculating the ratio of the current demand load to the limit load; if the ratio of the current demand load to the limit load is larger than the preset load threshold, limiting the ratio of the actual load of the engine to the limit load to the preset load threshold, and determining the target oil rail pressure according to the actual load and the current rotating speed; if the ratio of the current demand load to the limit load is not greater than the preset load threshold, the target oil rail pressure is directly determined according to the current demand load and the current rotating speed.
6. The value range of the preset load threshold is 60% -80%.
7. A high pressure rail pressure control system after failure of an intake phase sensor includes: the intake variable valve timing control module is used for controlling the intake variable valve timing to return to the locking position after the intake phase sensor fails; the rotating speed acquisition module is used for acquiring the current rotating speed of the air inlet cam shaft; the valve standard closing time acquisition module is used for acquiring a first closing time and a first opening time of the high-pressure oil pump control valve corresponding to the locking position at the current rotating speed; the valve target closing time acquisition module is used for determining target closing time according to the first closing time and determining target opening time according to the first opening time; the target oil rail pressure acquisition module is used for acquiring target oil rail pressure according to the current rotating speed; the actual oil rail pressure control module is used for controlling the actual oil rail pressure according to the target oil rail pressure in a time period from the target closing time to the target opening time; the high-pressure oil pump control valve is used for controlling the opening and closing of a low-pressure oil way.
8. The target rail pressure acquisition module includes: the current demand load acquisition unit is used for acquiring the opening of the accelerator and acquiring the current demand load of the engine according to the opening of the accelerator and the current rotating speed; and the target oil rail pressure determining unit is used for determining the target oil rail pressure according to the current demand load and the current rotating speed.
The drawbacks of the above prior art are:
1. since the prior art is based on intake phase sensor failure, the possibility of rail pressure sensor failure is not considered;
2. because the prior art does not consider the set flow rate of the high-pressure oil pump and the electric control relief valve and the conversion relation between the rail pressure and the fuel quality in the fuel rail, the rail pressure change generated after the actions of the high-pressure oil pump and the electric control relief valve is not estimated, and the rail pressure change is inaccurate;
3. because the rail pressure change generated after the actions of the high-pressure oil pump and the electric control pressure relief valve are estimated in the prior art is inaccurate, and the strategy of estimating the rail pressure as a rail pressure substitution value after the failure of the rail pressure sensor is not adopted, the rail pressure sensor cannot be used as a solution when the rail pressure is abnormal.
Disclosure of Invention
The present invention is directed to the above-mentioned problems, and an object of the present invention is to provide a control system and method for a rail pressure substitution value of a high-pressure common rail system of a diesel engine, which is to provide a solution when an abnormality occurs in rail pressure; and accurately estimating rail pressure change generated after the high-pressure oil pump and the electric control pressure relief valve act.
In order to solve the problems, the technical scheme provided by the invention is as follows:
a control system suitable for the rail pressure substitution value of a high-pressure common rail system of a diesel engine comprises a hydraulic system and an electronic control system EDC; wherein:
the hydraulic system comprises a high-pressure oil rail and a high-pressure oil pipe; wherein:
the electronic control system EDC comprises a sensor, the electronic control unit ECU, an actuator and a wire harness; wherein:
the sensor is used for collecting working condition information of the diesel engine in real time; the working condition information comprises a vehicle speed, a throttle opening, a crankshaft rotating speed, a camshaft rotating speed and a rail pressure signal;
the electronic control unit ECU is used for receiving the working condition information about the diesel engine acquired by the sensor, calculating the required fuel flow and the fuel injection quantity according to the working condition information, packaging the required fuel flow and the fuel injection quantity in the control signal and sending the control signal to the actuator;
the actuator comprises a high-pressure oil pump, a common rail oil injector, a pressure control valve, an electric control pressure release valve, a glow plug control unit, a boost pressure regulator, an exhaust gas circulation regulator and a throttle valve;
the common rail injector is used for atomizing and distributing fuel oil in a combustion chamber of the diesel engine;
the high-pressure fuel pump comprises a fuel metering valve and is used for compressing fuel from a low-pressure state to a high-pressure state through a plunger, so as to meet the requirements of a diesel engine on fuel injection pressure and fuel injection quantity; the high-pressure oil pump is also used for controlling the oil inlet amount;
the electric control pressure release valve is used for controlling oil output.
Preferably, the high pressure oil rail is used for storing fuel oil, and simultaneously, pressure fluctuation generated by the high pressure oil pump during oil supply and the common rail oil injector during oil injection is restrained, so that the pressure stability of the whole system of the diesel engine is ensured;
the high-pressure oil pump is connected with the high-pressure oil rail pipeline; the high-pressure oil pump conveys the fuel oil which is compressed from the low-pressure state to the high-pressure state through the plunger into the high-pressure oil rail through a pipeline;
the high-pressure oil rail is commonly owned and used for each cylinder of the diesel engine.
Preferably, the sensor comprises a pressure sensor; the pressure sensor is used for collecting the rail pressure signal in the high-pressure rail and providing the rail pressure signal for the electronic control unit ECU; the pressure sensor is mounted on the high pressure oil rail.
Preferably, a liquid flow buffer and a pressure limiter are arranged on the high-pressure oil rail; wherein:
the liquid flow buffer is used for cutting off the oil supply to the common rail oil injector when the common rail oil injector has a fuel leakage fault; the flow buffer is also used for reducing pressure fluctuation in the common rail and the high-pressure oil rail;
the pressure limiter is used for rapidly discharging the pressure in the high-pressure oil rail when the pressure abnormality occurs in the high-pressure oil rail.
Preferably, the common rail injector comprises a solenoid valve; the injection time and duration of the common rail injector are controlled by the electromagnetic valve; the electromagnetic valve controls the common rail fuel injector according to a control signal obtained by the calculation of the electronic control unit ECU;
the control method for the rail pressure substitution value of the high-pressure common rail system of the diesel engine by utilizing the control system for the rail pressure substitution value of the high-pressure common rail system of the diesel engine comprises the following steps:
s100, calculating to obtain rail pressure control deviation; then, S200 is performed;
s200, calculating the required fuel oil variation in the high-pressure oil rail according to the rail pressure control deviation calculated in the S100; then, S300 is performed;
s300, calculating to obtain the required fuel flow; then S400 is performed;
s400, judging whether fuel oil is required to be input or not; then according to the judgment result, the following operations are made:
if the judgment result is that fuel input is needed, S500 is executed;
if the judgment result is that the fuel input is not needed, S600 is executed;
s500, calculating to obtain the actual oil inlet quantity of the high-pressure oil pump; then S700 is performed;
s600, calculating to obtain the actual oil quantity which can be discharged by the electric control pressure release valve; then S700 is performed;
s700, calculating to obtain the estimated rail pressure of the actuator after the actuator acts; then S800 is performed;
s800, outputting the estimated rail pressure calculated in the S700 to serve as an alternative rail pressure; and then ending the control flow of the rail pressure substitution value of the high-pressure common rail system applicable to the diesel engine.
Preferably, S100 specifically comprises the following steps:
s110, acquiring the required rail pressure at the current moment;
s120, reading the estimated rail pressure of the previous period;
s130, subtracting the estimated rail pressure of the previous period read in the S120 from the required rail pressure obtained in the S110 to obtain the rail pressure control deviation.
Preferably, S200 specifically comprises the following steps:
s210, reading the rail pressure control deviation calculated in the S130;
s220, acquiring current rail pressure;
s230, dividing the rail pressure control deviation obtained through calculation in the S130 by a fuel mass under the current rail pressure to pressure conversion coefficient to obtain the required fuel variation in the high-pressure oil rail; wherein:
the fuel mass to pressure conversion factor for the current rail pressure is expressed as:
wherein: f is the conversion coefficient of the fuel mass to the pressure under the current rail; e is the liquid bulk modulus of elasticity at the current pressure and volume; v is the sum of the volumes of the high-pressure oil rail and the high-pressure oil pipe; ρ 1 And the fuel density is the current rail pressure.
Preferably, the fuel density at the current rail pressure in S230 is calculated as follows:
sa230 reading the current rail pressure;
sa231 reading the current atmospheric pressure;
sa232 look-up table to obtain the fuel density of the fuel currently in use at the current atmospheric pressure;
sa233 obtaining the liquid volume elastic modulus of the fuel under the current rail pressure by looking up a table, and obtaining the fuel compression coefficient by taking the reciprocal;
the fuel density under the current rail pressure is calculated according to the current rail pressure, the current atmospheric pressure, the fuel compression coefficient of the fuel in use at present and the fuel density of the fuel in use at the current atmospheric pressure, and is expressed by the following specific formula:
wherein: ρ 0 A fuel density at the current atmospheric pressure for the fuel currently being used; k is the fuel compression coefficient of the fuel which is currently being used, and the fuel compression coefficient and the liquid volume elastic modulus E are reciprocal; p (P) 0 Is the current atmospheric pressure; p (P) 1 And the current rail pressure.
Preferably, the bulk modulus of elasticity of the liquid at the current pressure and volume in S230 is expressed as follows:
compared with the prior art, the invention has the following advantages:
1. the invention considers the application scene of the failure of the rail pressure sensor, thereby being used as a solution when the rail pressure is abnormal;
2. the invention considers the set flow of the high-pressure oil pump and the electric control relief valve and the conversion relation between the rail pressure and the fuel quality in the fuel rail, thereby being capable of estimating the rail pressure change generated after the action of the high-pressure oil pump and the electric control relief valve and being very accurate.
Drawings
FIG. 1 is a schematic diagram of a prior art high pressure common rail fuel system configuration;
FIG. 2 is a flow chart of a control method according to an embodiment of the invention;
FIG. 3 is a schematic representation of actual rail pressure in accordance with an embodiment of the present invention;
FIG. 4 is a schematic diagram of an estimated rail pressure in accordance with an embodiment of the present invention.
Detailed Description
The present invention is further illustrated below in conjunction with specific embodiments, it being understood that these embodiments are meant to be illustrative of the invention only and not limiting the scope of the invention, and that modifications of the invention, which are equivalent to those skilled in the art to which the invention pertains, will fall within the scope of the invention as defined in the claims appended hereto.
A control system suitable for the rail pressure substitution value of a high-pressure common rail system of a diesel engine comprises a hydraulic system and an electronic control system EDC; wherein:
the hydraulic system comprises a high-pressure oil rail and a high-pressure oil pipe; wherein:
the electronic control system EDC comprises a sensor, an electronic control unit ECU, an actuator and a wire harness; wherein:
the sensor is used for collecting working condition information of the diesel engine in real time; the operating mode information comprises vehicle speed, throttle opening, crankshaft rotation speed, camshaft rotation speed and oil rail pressure signals.
In this particular embodiment, the sensor comprises a pressure sensor; the pressure sensor is used for collecting rail pressure signals in the high-pressure rail and providing the rail pressure signals for the electronic control unit ECU; the pressure sensor is mounted on the high pressure oil rail.
In this embodiment, the high-pressure oil rail is used for storing fuel, and at the same time, pressure fluctuation generated by the high-pressure oil pump during oil supply and the common rail oil injector during oil injection is restrained, so that the pressure stability of the whole system of the diesel engine is ensured.
In the specific embodiment, a high-pressure oil pump is connected with a high-pressure oil rail pipeline; the high-pressure oil pump delivers fuel, which has been compressed from a low-pressure state to a high-pressure state by the plunger, into the high-pressure oil rail through the pipe.
In this embodiment, the high pressure fuel rail is commonly owned and used for each cylinder of the diesel engine.
In the specific embodiment, a liquid flow buffer and a pressure limiter are arranged on the high-pressure oil rail; wherein:
the liquid flow buffer is used for cutting off the oil supply to the common rail oil injector when the common rail oil injector has the oil leakage fault; the flow buffers also serve to reduce pressure fluctuations in the common rail and the high pressure oil rail.
It should be noted that, the injection of the common rail injector may cause the fuel quality of the fuel in the common rail injector to decrease, so that the fuel injection amount needs to be added to the fuel change amount required in the high-pressure fuel rail, so as to obtain the required fuel flow controlled by the actuator.
The pressure limiter is used for rapidly discharging the pressure in the high-pressure oil rail when the pressure abnormality occurs in the high-pressure oil rail.
The electronic control unit ECU is used for receiving the working condition information about the diesel engine acquired by the sensor, calculating the required fuel flow and the fuel injection quantity according to the working condition information, packaging the required fuel flow and the fuel injection quantity in a control signal and sending the control signal to the actuator.
The actuator comprises a high-pressure oil pump, a common rail oil injector, a pressure control valve, an electric control relief valve, a glow plug control unit, a boost pressure regulator, an exhaust gas circulation regulator and a throttle valve.
In this embodiment, two actuators are provided in the system for rail pressure control.
Among the two actuators for rail pressure control, a high-pressure oil pump provided with a fuel metering valve is used for controlling the oil inlet amount, and an electric control relief valve is used for controlling the oil outlet amount; therefore, if the required fuel flow is greater than 0, the high-pressure oil pump is controlled to realize the required oil inlet amount when the fuel is required to be supplemented into the high-pressure oil rail, otherwise, the electric control relief valve is used for realizing the required oil outlet amount.
Common rail injectors are used to atomize and distribute fuel within the combustion chamber of a diesel engine.
In this embodiment, the common rail injector includes a solenoid valve; the injection time and duration of the common rail injector are controlled by the electromagnetic valve; the electromagnetic valve controls the common rail fuel injector according to the control signal calculated by the electronic control unit ECU.
The high-pressure oil pump comprises a fuel metering valve and is used for compressing fuel from a low-pressure state to a high-pressure state through the plunger, so as to meet the requirements of the diesel engine on fuel injection pressure and fuel injection quantity; the high pressure oil pump is also used to control the amount of oil intake.
The electric control pressure release valve is used for controlling the oil output.
As shown in fig. 2, a control method for a rail pressure substitution value of a high-pressure common rail system for a diesel engine, which uses the control system for a rail pressure substitution value of a high-pressure common rail system for a diesel engine, comprises the following steps:
s100, calculating to obtain a rail pressure control deviation delta P; then S200 is performed.
In this embodiment, S100 specifically includes the following steps:
s110, obtaining the required rail pressure at the current moment.
S120, the estimated rail pressure of the previous period is read.
S130, subtracting the estimated rail pressure of the previous period read in the S120 from the required rail pressure obtained in the S110 to obtain a rail pressure control deviation delta P.
The estimated rail pressure is the alternate rail pressure after the rail pressure sensor fails.
It should be further noted that the rail pressure control deviation Δp is the system demand rail pressure variation.
S200, calculating the required fuel oil variation in the high-pressure oil rail according to the rail pressure control deviation delta P calculated in the S100; then S300 is performed.
In this embodiment, S200 specifically includes the following steps:
s210, reading the rail pressure control deviation calculated in the S130.
S220, acquiring the current rail pressure.
S230, dividing the rail pressure control deviation obtained by calculation in the S130 by a conversion coefficient from the mass of the fuel under the current rail pressure to the pressure to obtain the required fuel variation in the high-pressure fuel rail; wherein:
the fuel mass to pressure conversion coefficient at the current rail pressure is expressed as formula (1):
wherein: f is a conversion coefficient from the fuel mass to the pressure under the current rail; e is the liquid bulk modulus of elasticity at the current pressure and volume; v is the sum of the volumes of the high-pressure oil rail and the high-pressure oil pipe; ρ 1 Is the fuel density at the current rail pressure.
The fuel mass to pressure conversion coefficient at the current rail pressure is also expressed by the formula (2):
wherein: and m is the fuel quality.
It should be further noted that the fuel mass to pressure conversion coefficient at the current rail pressure is also expressed by the formula (3):
it should be further noted that, the actual demand control flow of the actuator is multiplied by the conversion coefficient F from the fuel quality to the pressure, and the rail pressure is estimated after the actuator is calculated.
It should be further noted that, since the actual action of the actuator causes a certain delay in the change of the rail pressure, the estimated rail pressure needs to be output after a certain time delay as a substitute rail pressure when the rail pressure sensor fails.
In this embodiment, the fuel density under the current rail in S230 is calculated as follows:
sa230 read the current rail pressure.
Sar231. Read the current atmospheric pressure.
Sa232A look-up table obtains the fuel density of the fuel currently in use at the current atmospheric pressure.
The Sa233 is used for obtaining the liquid volume elastic modulus of the fuel under the current rail pressure by looking up a table, and obtaining the fuel compression coefficient by taking the reciprocal.
The fuel density under the current rail pressure is calculated according to the current rail pressure, the current atmospheric pressure, the fuel compression coefficient of the fuel in use at present and the fuel density of the fuel in use at the current atmospheric pressure, and is expressed by a specific formula (4):
wherein: ρ 0 The fuel density at the current atmospheric pressure for the fuel currently being used; k is the currentThe fuel compression factor of the fuel being used; p (P) 0 Is the current atmospheric pressure; p (P) 1 Is the current rail pressure.
Since the fuel compression coefficient K and the liquid bulk modulus E are reciprocal, the fuel density at the present rail pressure is also expressed by the formula (5):
it should be further noted that this is an empirical formula of fuel density as a function of pressure.
It should be further noted that this step of calculation is based on a fixed high pressure rail volume.
In this embodiment, the bulk modulus of liquid at the current pressure and volume in S230 is expressed by the formula (6):
the fuel mass to pressure conversion coefficient at the current rail pressure is also expressed in the expression (7) according to the expression of the liquid bulk modulus at the current pressure and volume:
s300, calculating to obtain the required fuel flow; and then S400 is performed.
S400, judging whether fuel oil is required to be input or not; then according to the judgment result, the following operations are made:
if the determination result is that fuel input is required, S500 is performed.
If the determination result is that fuel input is not required, S600 is performed.
S500, calculating to obtain the actual oil inlet quantity of the high-pressure oil pump; then S700 is performed.
S600, calculating to obtain the actual oil output of the electric control pressure release valve; then S700 is performed.
It should be noted that, the working capacity of the actuator is physically limited, so the required fuel flow needs to be limited by the actual fuel-able amount of the high-pressure oil pump or the actual fuel-able amount of the electrically-controlled pressure relief valve before the actual required control flow of the actuator is obtained.
S700, calculating to obtain the estimated rail pressure of the actuator after the actuator acts; then S800 is performed.
S800, outputting the estimated rail pressure calculated in the S700 to serve as a substitute rail pressure; and then ending the control flow of the rail pressure substitution value of the high-pressure common rail system applicable to the diesel engine.
In order to further demonstrate the technical effects of the present invention, the present embodiment further performs a real machine test, and the specific cases are as follows:
experiments an example of a six cylinder diesel engine application manufactured by applicant was the subject of the experiment. As shown in fig. 3-4, the actual rail pressure curve and the estimated rail pressure curve are obtained in the operation process after the fault of the excessively low voltage of the active manufacturing rail pressure sensor.
The conclusion is evident from fig. 3 to 4: when the rail pressure sensor fails, the system and the method can accurately calculate and obtain the estimated rail pressure, the estimated rail pressure has extremely high coincidence degree with the actual rail pressure change trend, and the deviation of the stable working condition is within 50 bar.
In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate preferred embodiment of this invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. As will be apparent to those skilled in the art; various modifications to these embodiments will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
The foregoing description includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, as used in the specification or claims, the term "comprising" is intended to be inclusive in a manner similar to the term "comprising," as interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean "non-exclusive or".
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The utility model provides a control system suitable for diesel engine high pressure common rail system rail pressure substitution value which characterized in that: comprises a hydraulic system and an electronic control system EDC; wherein:
the hydraulic system comprises a high-pressure oil rail and a high-pressure oil pipe; wherein:
the electronic control system EDC comprises a sensor, the electronic control unit ECU, an actuator and a wire harness; wherein:
the sensor is used for collecting working condition information of the diesel engine in real time; the working condition information comprises a vehicle speed, a throttle opening, a crankshaft rotating speed, a camshaft rotating speed and a rail pressure signal;
the electronic control unit ECU is used for receiving the working condition information about the diesel engine acquired by the sensor, calculating the required fuel flow and the fuel injection quantity according to the working condition information, packaging the required fuel flow and the fuel injection quantity in the control signal and sending the control signal to the actuator;
the actuator comprises a high-pressure oil pump, a common rail oil injector, a pressure control valve, an electric control pressure release valve, a glow plug control unit, a boost pressure regulator, an exhaust gas circulation regulator and a throttle valve;
the common rail injector is used for atomizing and distributing fuel oil in a combustion chamber of the diesel engine;
the high-pressure fuel pump comprises a fuel metering valve and is used for compressing fuel from a low-pressure state to a high-pressure state through a plunger, so as to meet the requirements of a diesel engine on fuel injection pressure and fuel injection quantity; the high-pressure oil pump is also used for controlling the oil inlet amount;
the electric control pressure release valve is used for controlling oil output.
2. The control system for rail pressure substitution values of a high pressure common rail system for a diesel engine according to claim 1, wherein: the high-pressure oil rail is used for storing fuel oil and simultaneously inhibiting pressure fluctuation generated by the high-pressure oil pump during oil supply and the common rail oil injector during oil injection so as to ensure the pressure stability of the whole system of the diesel engine;
the high-pressure oil pump is connected with the high-pressure oil rail pipeline; the high-pressure oil pump conveys the fuel oil which is compressed from the low-pressure state to the high-pressure state through the plunger into the high-pressure oil rail through a pipeline;
the high-pressure oil rail is commonly owned and used for each cylinder of the diesel engine.
3. The control system for rail pressure substitution values of a high pressure common rail system for a diesel engine according to claim 2, wherein: the sensor comprises a pressure sensor; the pressure sensor is used for collecting the rail pressure signal in the high-pressure rail and providing the rail pressure signal for the electronic control unit ECU; the pressure sensor is mounted on the high pressure oil rail.
4. The control system for rail pressure substitution values of a high pressure common rail system for a diesel engine according to claim 3, wherein: the high-pressure oil rail is provided with a liquid flow buffer and a pressure limiter; wherein:
the liquid flow buffer is used for cutting off the oil supply to the common rail oil injector when the common rail oil injector has a fuel leakage fault; the flow buffer is also used for reducing pressure fluctuation in the common rail and the high-pressure oil rail;
the pressure limiter is used for rapidly discharging the pressure in the high-pressure oil rail when the pressure abnormality occurs in the high-pressure oil rail.
5. The control system for rail pressure substitution values of a high pressure common rail system for a diesel engine of claim 4, wherein: the common rail injector comprises an electromagnetic valve; the injection time and duration of the common rail injector are controlled by the electromagnetic valve; and the electromagnetic valve controls the common rail fuel injector according to a control signal obtained by calculation of the electronic control unit ECU.
6. A control method for a rail pressure substitution value of a high-pressure common rail system for a diesel engine using the control system for a rail pressure substitution value of a high-pressure common rail system for a diesel engine according to claim 5, characterized by: comprises the following steps:
s100, calculating to obtain rail pressure control deviation; then, S200 is performed;
s200, calculating the required fuel oil variation in the high-pressure oil rail according to the rail pressure control deviation calculated in the S100; then, S300 is performed;
s300, calculating to obtain the required fuel flow; then S400 is performed;
s400, judging whether fuel oil is required to be input or not; then according to the judgment result, the following operations are made:
if the judgment result is that fuel input is needed, S500 is executed;
if the judgment result is that the fuel input is not needed, S600 is executed;
s500, calculating to obtain the actual oil inlet quantity of the high-pressure oil pump; then S700 is performed;
s600, calculating to obtain the actual oil quantity which can be discharged by the electric control pressure release valve; then S700 is performed;
s700, calculating to obtain the estimated rail pressure of the actuator after the actuator acts; then S800 is performed;
s800, outputting the estimated rail pressure calculated in the S700 to serve as an alternative rail pressure; and then ending the control flow of the rail pressure substitution value of the high-pressure common rail system applicable to the diesel engine.
7. The control method for rail pressure substitution value of high-pressure common rail system for diesel engine according to claim 6, characterized by: s100 specifically comprises the following steps:
s110, acquiring the required rail pressure at the current moment;
s120, reading the estimated rail pressure of the previous period;
s130, subtracting the estimated rail pressure of the previous period read in the S120 from the required rail pressure obtained in the S110 to obtain the rail pressure control deviation.
8. The control method for rail pressure substitution value of high-pressure common rail system for diesel engine according to claim 7, characterized in that: s200 specifically comprises the following steps:
s210, reading the rail pressure control deviation calculated in the S130;
s220, acquiring current rail pressure;
s230, dividing the rail pressure control deviation obtained through calculation in the S130 by a fuel mass under the current rail pressure to pressure conversion coefficient to obtain the required fuel variation in the high-pressure oil rail; wherein:
the fuel mass to pressure conversion factor for the current rail pressure is expressed as:
wherein: f is the conversion coefficient of the fuel mass to the pressure under the current rail; e is the liquid bulk modulus of elasticity at the current pressure and volume; v is the sum of the volumes of the high-pressure oil rail and the high-pressure oil pipe; ρ 1 And the fuel density is the current rail pressure.
9. The control method for rail pressure substitution value of high-pressure common rail system for diesel engine according to claim 8, characterized by: the fuel density under the current rail in S230 is calculated as follows:
sa230 reading the current rail pressure;
sa231 reading the current atmospheric pressure;
sa232 look-up table to obtain the fuel density of the fuel currently in use at the current atmospheric pressure;
sa233 obtaining the liquid volume elastic modulus of the fuel under the current rail pressure by looking up a table, and obtaining the fuel compression coefficient by taking the reciprocal;
the fuel density under the current rail pressure is calculated according to the current rail pressure, the current atmospheric pressure, the fuel compression coefficient of the fuel in use at present and the fuel density of the fuel in use at the current atmospheric pressure, and is expressed by the following specific formula:
wherein: ρ 0 A fuel density at the current atmospheric pressure for the fuel currently being used; k is the fuel compression coefficient of the fuel currently being used; p (P) 0 Is the current atmospheric pressure; p (P) 1 And the current rail pressure.
10. The control method for rail pressure substitution value of high-pressure common rail system for diesel engine according to claim 9, characterized by: the bulk modulus of elasticity of the liquid at the current pressure and volume in S230 is expressed as follows:
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| CN202311050541.0A CN117287324A (en) | 2023-08-21 | 2023-08-21 | Control system and method suitable for rail pressure substitution value of high-pressure common rail system of diesel engine |
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| CN202311050541.0A CN117287324A (en) | 2023-08-21 | 2023-08-21 | Control system and method suitable for rail pressure substitution value of high-pressure common rail system of diesel engine |
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