Load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method

Abstract

The application discloses a load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method, comprising a flow control valve, an engine controller, a one-way valve, a high-pressure oil pump, a high-pressure common rail pipe, a rail pressure sensor, a high-pressure oil pipe and an oil injector; the flow control valve receives a duty cycle signal from the engine controller to adjust the flow into the fuel system; the high-pressure oil pump is used for compressing low-pressure fuel from the flow control valve into high-pressure fuel; the one-way valve is used for preventing fuel backflow; the load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method realizes the dynamic balance of the oil amount into the high-pressure fuel pipe system and the consumption amount, and converts the integral compensation adjustment component into part of the high-pressure fuel consumption feedforward component through the memory conversion mode, reduces the integral compensation adjustment range, and improves the accuracy of the high-pressure pipe system oil amount calculation.

Description

Technical Field

[0001] This invention relates to the field of diesel engine control technology, specifically to a method for controlling and calibrating rail pressure in a load-sensitive high-pressure common rail diesel engine. Background Technology

[0002] The rail pressure stability of a high-pressure common rail diesel engine has a significant impact on engine performance such as burst pressure, speed stability, emission performance stability, and thermal stability. Therefore, rail pressure control of a high-pressure common rail diesel engine is an important part of the high-pressure common rail diesel engine control system.

[0003] The fuel injection quantity of a high-pressure common rail diesel engine is affected by changes in the engine load. When used in construction machinery, marine main engines, or generator sets with sudden acceleration and deceleration requirements, the variable load of the diesel engine leads to variable fuel injection quantity. When the fuel injection quantity varies, the fuel output of the high-pressure fuel line also varies, forming a variable load effect on the high-pressure common rail fuel line. This has a significant impact on rail pressure fluctuations, requiring a load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method.

[0004] Existing technologies, such as patent CN102192033A, use equipment and methods for controlling the high-pressure common rail system of a diesel engine to obtain feedforward control quantities through PID feedback regulation. It details feedforward components such as high-pressure oil pumps, injectors, and flow metering valves, along with PID feedback control methods. PID feedback control is the core of this technology; inaccurate PID calculations lead to inaccurate control. However, PID control quantities are complex and heavily rely on operator experience and skill. The published technology lacks a description of the PID control strategy. Secondly, this technology uses the acquired feedback value as the feedforward input value, achieving control regulation through high-pressure oil pumps, flow metering valves, and other control quantities, and provides detailed calculation methods for control. However, it is well known that physical components are wear-prone, and even components of uniform specifications from different samples have errors. The technology lacks content related to error elimination, resulting in inaccurate calculation of the high-pressure piping oil quantity. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the existing defects and provide a load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method, so as to achieve dynamic balance between the amount of fuel entering the high-pressure fuel system and the amount of fuel consumed. By using memory conversion, the integral compensation adjustment component is converted into a part of the high-pressure fuel consumption feedforward component, thereby reducing the integral compensation adjustment range and improving the accuracy of high-pressure fuel system quantity calculation. This can effectively solve the problems in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method, comprising a flow control valve, an engine controller, a check valve, a high-pressure oil pump, a high-pressure common rail pipe, a rail pressure sensor, a high-pressure oil pipe, and an injector;

[0007] The flow control valve receives a duty cycle signal from the engine controller to regulate the flow rate into the fuel system;

[0008] A high-pressure fuel pump is used to compress low-pressure fuel from a flow control valve into high-pressure fuel.

[0009] A check valve is used to prevent fuel backflow;

[0010] The specific steps are as follows:

[0011] First, the total fuel injection quantity F of the injector is measured. inj Total leakage D from the gap between the high-pressure oil pump and the injector inj Obtain the feedforward component F of high-pressure fuel consumption of diesel engine con ;

[0012] Then, in response to the phenomenon of the difference between the high-pressure fuel consumption and the fuel entering the high-pressure fuel pipeline, supplementary adjustment is achieved by integrating the difference between the target value and the actual value to compensate for the gradual change in high-pressure fuel consumption caused by the wear of the high-pressure fuel pump and injector clearance, as well as the calculation error of the high-pressure fuel consumption feedforward value. This forms a two-stage adjustment strategy of feedforward component of rail pressure and integral compensation adjustment component.

[0013] The integral compensation value is used to form an adjustment memory, and the integral compensation adjustment component is converted into a part of the high-pressure fuel consumption feedforward component, thereby reducing the integral compensation adjustment range. At the same time, the compressibility of the high-pressure pipeline system and fuel under high-pressure conditions is utilized to form a high-pressure pipeline accumulator component.

[0014] Ultimately, the high-pressure fuel consumption feedforward component, integral compensation adjustment component, and high-pressure pipeline accumulator component are coupled to achieve a dynamic balance between the amount of fuel entering the high-pressure fuel pipeline and the amount consumed.

[0015] As a preferred technical solution of the present invention, a high-pressure oil pump flow rate map is established under the maximum high-pressure oil pump outlet pressure Prail requirement of the system, and the injection duration t of the injector given by the engine controller is obtained through component platform tests. hub Fuel injection quantity F under rail pressure and Prail conditions hub The engine controller can be configured to control the number of injectors (m) and the injection duration (t). hub Rail pressure (Prail) and diesel engine speed (n) eng Obtain the total fuel injection quantity F of the injector inj .

[0016] As a preferred embodiment of the present invention, the high-pressure fuel consumption feedforward component F of the diesel engine con The total fuel injection quantity F of the injector inj Total leakage D from the gap between the injector and the fuel injector inj sum.

[0017] As a preferred embodiment of the present invention, the high-pressure fuel consumption feedforward component F of the diesel engine con Rail pressure integral compensation adjustment component F needs to be used. KI Compensation will be provided.

[0018] As a preferred technical solution of the present invention, the target rail pressure P is obtained. req Fuel quantity Q in high-pressure piping system under certain conditions req Fuel quantity Q in the high-pressure piping system under actual rail pressure (Prail) conditions act To further obtain the target equilibrium orbital pressure P req The fuel replenishment requirement ΔQ between the actual rail pressure (Prail) and the actual rail pressure (Prail), where ΔQ = Q req -Q act If it is required to replenish the required amount of oil within time t, then the oil replenishment rate is: The rail pressure integral compensation adjustment component

[0019] As a preferred technical solution of the present invention, the rail pressure integral compensation adjustment component F during the previous stable running period is... KI The integral compensation amount F for the feedforward component of high-pressure fuel consumption in diesel engines con-KI The dynamic balance of the inlet and outlet flow of the high-pressure common rail is achieved by combining the integral compensation amount of the diesel engine high-pressure fuel consumption feedforward component calculated based on the injector physical model with the integral compensation amount of the diesel engine high-pressure fuel consumption feedforward component obtained based on the rail pressure integral compensation adjustment component, and the flow rate of the high-pressure fuel pump under the current rail pressure. The expression is as follows:

[0020] Compared with the prior art, the beneficial effects of this invention are as follows: This load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method achieves dynamic balance of high-pressure common rail pressure by establishing a dynamic balance between the flow rate of the high-pressure oil pump entering the high-pressure common rail system and the fuel consumption flowing out of the high-pressure common rail system. This can address the rail pressure fluctuation problem caused by large load changes in the high-pressure common rail diesel engine. Furthermore, for the mismatch between calculated and actual values ​​of high-pressure oil pump flow rate and fuel consumption due to metering errors or component wear, an integral compensation method is used to compensate for and resolve this issue. The integral compensation value is then fixed through memory to reduce the adjustment range and calculation workload of the integral compensation amount. When calculating the integral compensation amount, the pressure storage performance of the high-pressure common rail system, such as the common rail system volume and fuel compressibility, is fully considered, thereby improving the accuracy of high-pressure system fuel quantity calculation. Attached Figure Description

[0021] Figure 1 This is a diagram illustrating the control system composition of the present invention;

[0022] Figure 2 This is a flowchart of the control system of the present invention.

[0023] In the diagram: 1. Flow control valve, 2. Engine controller, 3. Check valve, 4. High-pressure oil pump, 5. High-pressure common rail, 6. Rail pressure sensor, 7. High-pressure oil pipe, 8. Injector. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figure 1-2 This invention provides a technical solution: a load-sensitive high-pressure common rail diesel engine rail pressure control and calibration method, including a flow control valve 1, an engine controller 2, a check valve 3, a high-pressure fuel pump 4, a high-pressure common rail pipe 5, a rail pressure sensor 6, a high-pressure fuel pipe 7, and fuel injectors 8. The output end of the engine controller 2 is connected to the input end of the flow control valve 1. A check valve 3 is installed on the pipeline between the flow control valve 1 and the high-pressure fuel pump 4. The output end of the high-pressure fuel pump 4 is connected to the high-pressure common rail pipe 5 through the high-pressure fuel pipe 7. A check valve 3 is also installed on the high-pressure common rail pipe 5. The high-pressure common rail pipe 5 is connected to multiple fuel injectors 8. The rail pressure sensor 6 is installed on the high-pressure common rail pipe for detecting fuel pressure.

[0026] The flow control valve 1 receives a duty cycle signal from the engine controller 2 to regulate the flow rate into the fuel system;

[0027] The high-pressure oil pump 4 is used to compress low-pressure fuel from the flow control valve 1 into high-pressure fuel.

[0028] One-way valve 3 is used to prevent fuel backflow;

[0029] The pipeline system can be divided into control signal transmission lines, fuel operation lines, and fuel leakage lines.

[0030] Because of the leakage D between the four plungers of the high-pressure oil pump P It then flows to the outlet of flow control valve 1, which is also the inlet of high-pressure oil pump 4. Therefore, the actual flow rate F of flow control valve 1 is... I Equivalent to the oil volume F of the high-pressure oil pump P ;

[0031] Furthermore, the oil flow rate F of the high-pressure oil pump 4 under the control conditions of the flow control valve 1 can be obtained through device platform testing. P and flow control valve 1 flow rate F I Establish a system based on the high-pressure oil pump speed n P and flow control valve 1 flow rate F I Using the coordinate axes as the coordinates, and the duty cycle signal (Duty) received by the flow control valve 1 from the engine controller 2 as the control variable, form a three-dimensional map.

[0032] Furthermore, the flow control valve 1 is affected by both the duty cycle and the power supply voltage U. Since the power supply voltage U is reasonable within a certain range, a correction for the power supply voltage is required. The preferred standard duty cycle (Duty) is the control quantity under 24VDC voltage. The actual duty cycle of the flow control valve 1 is... U act The actual power supply voltage is used. In particular, due to the influence of factors such as duty cycle control reactance, the effect of duty cycle on voltage change is nonlinear. However, in this scheme, the calculation error can be eliminated by integral compensation method.

[0033] Furthermore, the outlet pressure Prail of high-pressure oil pump 4 affects the oil volume F of high-pressure oil pump 4. P This has an impact, and to reduce the complexity of component platform testing, only the high-pressure oil pump flow rate map under the standard high-pressure oil pump 4 outlet pressure Prail condition is established. Preferably, the high-pressure oil pump flow rate map is established under the system's maximum high-pressure oil pump 4 outlet pressure Prail requirement. The oil flow rate F of the other high-pressure oil pumps 4 under the other high-pressure oil pump 4 outlet pressure Prail conditions is also considered. p The following methods were used for correction:

[0034] F P-prailPmax is the flow rate of high-pressure oil pump 4 under the current outlet pressure condition, Pmax is the maximum outlet pressure of high-pressure oil pump 4, which is the outlet pressure of high-pressure oil pump 4 corresponding to the standard high-pressure oil pump 4 flow rate map, Prail is the current outlet pressure of high-pressure oil pump 4, and K is a correction coefficient, which is recommended to be less than 5% and can be obtained based on the platform test of high-pressure oil pump 4.

[0035] Furthermore, the injection duration t of the injector 8 given by the engine controller 2 can be obtained through component platform testing. hub Fuel injection quantity F under rail pressure and Prail conditions hub Thus, the engine controller 2 can control the number of injectors 8 (m) and the injection duration (t). hub Rail pressure (Prail) and diesel engine speed (n) eng Obtain the total fuel injection quantity F of injector 8 inj :

[0036]

[0037] Furthermore, the leakage amount D of injector 8 hub The total leakage rate D of injector 8 was obtained through platform testing of the injector. inj =m×D hub .

[0038] Furthermore, the feedforward component F of high-pressure fuel consumption in diesel engines con The total fuel injection quantity F of injector 8 inj Total leakage D of injector 8 inj In particular, if the fuel system contains other components that consume high-pressure fuel, these should also be included in the diesel engine high-pressure fuel consumption feedforward component F. con middle.

[0039] Furthermore, the feedforward component F of high-pressure fuel consumption in the diesel engine can be increased. con With high-pressure oil pump oil quantity F P A balance is established between them, so that when the amount of fuel exiting the high-pressure pipeline is equal to the amount of fuel entering the high-pressure pipeline, the rail pressure is always in a balanced state.

[0040] Furthermore, it's important to understand that because the flow control valve 1, high-pressure oil pump 4, and injector 8 are mechanical components, wear is an objective reality. When worn, their performance will change and may not match the actual values. Additionally, factors such as the fuel injection quantity F of injector 8 will also affect performance. hub High-pressure oil pump 4 flow rate F P The data is obtained using the map calculation method. However, map methods cannot be comprehensive, and the difference parameters will contain errors. Furthermore, there are errors in the actual performance of different samples of the same model, which affects the actual feedforward component F of the high-pressure fuel consumption of the diesel engine. conWith high-pressure oil pump oil quantity F P It is difficult to establish an accurate balance between them, so it is necessary to use the rail pressure integral compensation adjustment component F. KI Compensation will be provided.

[0041] Furthermore, the amount of fuel Q in the high-pressure piping system under each rail pressure Prail is calculated. act The amount of fuel in the high-pressure piping system is equal to the total volume V of the high-pressure piping system and the fuel density ρ under the actual rail pressure. act The product of: Q act =V×ρ act Preferred ρ act The total volume V of the high-pressure piping system can be obtained by establishing a corresponding map with the rail pressure (Prail). This volume is a structural parameter.

[0042] Preferably, fuel density can be obtained by consulting published values, or it can be obtained using the following formula:

[0043] ρ p Let ρ be the fuel density under the current pressure conditions. p-1 This refers to the fuel density under the previous pressure unit condition, where one pressure unit is MPa or kJ. p-1 Let k be the elastic model of fuel under pressure p-1. p = k0 + γ × P, where k0 is the elastic modulus under standard conditions (0 MPa), which is taken as 1070 for light diesel oil, and γ is the elastic modulus increment coefficient, which is taken as 7.15 for light diesel oil. The density of light fuel oil under standard conditions (pressure 0 MPa) is 848 kg / m³. 3 .

[0044] In particular, it is important to note that the pressure unit is 1 MPa. Therefore, the measured high-pressure fuel pressure needs to be rounded to the nearest MPa. Under normal circumstances, a rail pressure fluctuation of 1 MPa is considered ideal. Therefore, rounding the rail pressure to the nearest MPa helps reduce the computational load on the engine controller 2.

[0045] Furthermore, the target orbital pressure P can be obtained. req Fuel quantity Q in high-pressure piping system under certain conditions req Fuel quantity Q in the high-pressure piping system under actual rail pressure (Prail) conditions act Thus, the target orbital pressure P is obtained. req The fuel replenishment requirement ΔQ between the actual rail pressure (Prail) and the actual rail pressure (Prail), where ΔQ = Q req -Q act If it is required to replenish the required amount of oil within time t, then the oil replenishment rate is: In particular, the fuel replenishment time t can also be equated to the integral time parameter.

[0046] Furthermore, the rail pressure integral compensation adjustment component A basic integration time t can be established; the larger the rail pressure deviation, the smaller the integration time t should be.

[0047] Furthermore, the integral compensation adjustment component F from the previous stable running period is... KI The integral compensation amount F for the feedforward component of high-pressure fuel consumption in diesel engines con-KI This is used to compensate for the high-pressure fuel consumption feedforward component F of diesel engines caused by factors such as metering errors and component wear. con The measurement is inaccurate.

[0048] Furthermore, the dynamic balance of the inlet and outlet flow of the high-pressure common rail is achieved by the sum of the feedforward component of the high-pressure fuel consumption of the diesel engine calculated based on the injector physical model, the integral compensation amount of the feedforward component of the high-pressure fuel consumption of the diesel engine obtained based on the rail pressure integral compensation adjustment component, and the rail pressure integral compensation adjustment component, and the flow rate of the high-pressure fuel pump under the current rail pressure. The expression is as follows:

[0049] The parts of the invention not described in detail are prior art. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling and calibrating rail pressure of a load-sensitive high-pressure common rail diesel engine, characterized in that: Includes a flow control valve (1), an engine controller (2), a check valve (3), a high-pressure oil pump (4), a high-pressure common rail (5), a rail pressure sensor (6), a high-pressure oil pipe (7), and an injector (8); The flow control valve (1) receives a duty cycle signal from the engine controller (2) to regulate the flow rate into the fuel system; The high-pressure oil pump (4) is used to compress low-pressure fuel from the flow control valve (1) into high-pressure fuel; One-way valve (3) is used to prevent fuel backflow; The specific steps are as follows: First, the total fuel injection quantity F of the injector is measured. inj Total leakage D from the gap between the high-pressure oil pump and the injector inj Obtain the feedforward component F of high-pressure fuel consumption of diesel engine con ; Obtain the target orbital pressure P req Fuel quantity Q in high-pressure piping system under certain conditions req Fuel quantity Q in the high-pressure piping system under actual rail pressure (Prail) conditions act To further obtain the target orbital pressure P for balance req The fuel replenishment requirement ΔQ between the actual rail pressure (Prail) and the actual rail pressure (Prail), where ΔQ = Q req -Q act Given that it is required to replenish the necessary amount of oil within time t, the oil replenishment rate is: Rail pressure integral compensation adjustment component ; The rail pressure integral compensation adjustment component F from the previous stable running period. KI The integral compensation amount F for the feedforward component of high-pressure fuel consumption in diesel engines con-KI The dynamic balance of the inlet and outlet flow of the high-pressure common rail is achieved by combining the integral compensation amount of the diesel engine high-pressure fuel consumption feedforward component calculated based on the injector physical model with the integral compensation amount of the diesel engine high-pressure fuel consumption feedforward component obtained based on the rail pressure integral compensation adjustment component, and the flow rate of the high-pressure fuel pump under the current rail pressure. The expression is as follows: F P-prail This indicates the flow rate of the high-pressure oil pump under the current rail pressure, thereby achieving a dynamic balance between the amount of oil entering and consuming the high-pressure fuel system through control.

2. The method for controlling and calibrating rail pressure of a load-sensitive high-pressure common rail diesel engine according to claim 1, characterized in that: Establish a high-pressure oil pump flow rate map under the maximum high-pressure oil pump outlet pressure requirement of the system, and obtain the injection duration t of the injector given by the engine controller through component platform tests. hub Fuel injection quantity F under rail pressure conditions hub The engine controller can be configured to control the number of injectors (m) and the injection duration (t). hub Rail pressure and diesel engine speed n eng Obtain the total fuel injection quantity F of the injector inj .

3. The method for controlling and calibrating rail pressure of a load-sensitive high-pressure common rail diesel engine according to claim 2, characterized in that: The high-pressure fuel consumption feedforward component F of the diesel engine con The total fuel injection quantity F of the injector inj Total leakage D from the gap between the injector and the fuel injector inj sum.

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