A control system and method for rail pressure substitute value of diesel engine high-pressure common rail system

Abstract

The present application relates to a control system for rail pressure replacement value of diesel engine high-pressure common rail system, comprising 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 present application also relates to a control method for rail pressure replacement value of diesel engine high-pressure common rail system, comprising the following steps: calculating a rail pressure control deviation; calculating a required fuel change amount; calculating a required fuel flow; calculating an actual available oil intake amount and an actual available oil output amount; and calculating an estimated rail pressure. The present application provides a solution when rail pressure is abnormal; and the rail pressure change after the action of the high-pressure oil pump and the electronically controlled pressure relief valve is accurately estimated.

Description

Technical Field

[0001] This invention relates to the field of control technology for high-pressure common rail fuel systems for diesel engines, and more specifically to a control system and method for rail pressure substitution values ​​applicable to high-pressure common rail systems for diesel engines. Background Technology

[0002] like Figure 1 As shown, the existing high-pressure common rail fuel system generally has the following structure: low-pressure fuel is pumped out of the fuel tank by a low-pressure fuel pump, filtered by a fuel filter, and then pressurized by a high-pressure fuel pump into the fuel rail. The fuel flow rate of the high-pressure fuel pump is controlled by the fuel metering unit.

[0003] The fuel rail is equipped with a rail pressure sensor and an electronically controlled pressure regulating valve. The rail pressure sensor measures the pressure level within the fuel rail, serving as a feedback signal for rail pressure closed-loop control. When the rail pressure sensor fails, the system needs to provide a substitute rail pressure value for closed-loop control. The electronically controlled pressure regulating valve can quickly release fuel to reduce rail pressure for rail pressure control. The injectors are connected to the fuel rail via high-pressure fuel lines to inject the required amount of fuel into the cylinders. The fuel metering unit (MeUn), the electronically controlled pressure relief valve (ePRV), and the injectors are all controlled by the electronic control unit (ECU).

[0004] Based on the above-mentioned high-pressure common rail fuel system structure, the existing technical solution for calculating the alternative value of the fuel rail pressure is the lookup table method. Specifically, in common technical solutions, when the rail pressure sensor fails, the alternative value of the rail pressure is calculated by looking up a table using parameters such as engine speed and fuel injection quantity.

[0005] The drawback of the existing table lookup method is that:

[0006] Because the method of calculating the rail pressure substitution value by looking up the table can only provide a pre-calibrated, empirical substitution value, and cannot be adjusted according to the actual working conditions, its accuracy is low.

[0007] A very small number of existing technologies have adopted other control strategies to cope with sensor failure; the most typical example is Chinese invention patent application CN202110848457.8, entitled "High-Pressure Oil Rail Pressure Control Method and System after Intake Phase Sensor Failure", which discloses the following technical solution:

[0008] 1. A method for controlling high-pressure fuel rail pressure after intake phase sensor failure, comprising: after intake phase sensor failure, controlling intake variable valve timing to return to the locked position; acquiring the current speed of the intake camshaft; acquiring the first closing time and the first opening time of the high-pressure fuel pump control valve corresponding to the locked position at the current speed; determining a target closing time based on the first closing time, and determining a target opening time based on the first opening time; acquiring a target fuel rail pressure based on the current speed; and controlling the actual fuel rail pressure based on the target fuel rail pressure during the time period from the target closing time to the target opening time; wherein, the intake variable valve timing is installed on the intake camshaft, and the high-pressure fuel pump control valve is used to control the opening and closing of the low-pressure fuel circuit.

[0009] 2. Determine the target closing time based on the first closing time, and determine the target opening time based on the first opening time, including: using the first closing time as the target closing time and the first opening time as the target opening time.

[0010] 3. After obtaining the current speed of the intake camshaft, the method further includes: obtaining the set of closing times and the set of opening times of the high-pressure oil pump control valve corresponding to any position of the intake variable valve timing at the current speed; determining the target closing time based on the first closing time, and determining the target opening time based on the first opening time, including: taking the maximum time in the first closing time and the set of closing times as the target closing time, and taking the minimum time in the first opening time and the set of opening times as the target opening time.

[0011] 4. Obtain the target fuel rail pressure based on the current engine speed, including: obtaining the throttle opening; obtaining the current engine load demand based on the throttle opening and the current engine speed; and determining the target fuel rail pressure based on the current load demand and the current engine speed.

[0012] 5. Determine the target fuel rail pressure based on the current demand load and current engine speed, including: obtaining the engine's limit load at the current engine 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 greater than a preset load threshold, then limit the ratio of the engine's actual load to the limit load to the preset load threshold, and determine the target fuel rail pressure based on the actual load and current engine speed; if the ratio of the current demand load to the limit load is not greater than the preset load threshold, then directly determine the target fuel rail pressure based on the current demand load and current engine speed.

[0013] 6. The preset load threshold range is 60%-80%.

[0014] 7. A high-pressure fuel rail pressure control system for use after intake phase sensor failure includes: an intake variable valve timing control module for controlling the intake variable valve timing to return to the locked position after intake phase sensor failure; a speed acquisition module for acquiring the current speed of the intake camshaft; a valve standard closing time acquisition module for acquiring the first closing time and the first opening time of the high-pressure fuel pump control valve corresponding to the locked position at the current speed; a valve target closing time acquisition module for determining the target closing time based on the first closing time and the target opening time based on the first opening time; a target fuel rail pressure acquisition module for acquiring the target fuel rail pressure based on the current speed; and an actual fuel rail pressure control module for controlling the actual fuel rail pressure based on the target fuel rail pressure during the time period from the target closing time to the target opening time; wherein the intake variable valve timing is mounted on the intake camshaft, and the high-pressure fuel pump control valve is used to control the opening and closing of the low-pressure fuel circuit.

[0015] 8. The target fuel rail pressure acquisition module includes: a current demand load acquisition unit, used to acquire the throttle opening and acquire the current demand load of the engine based on the throttle opening and the current speed; and a target fuel rail pressure determination unit, used to determine the target fuel rail pressure based on the current demand load and the current speed.

[0016] The shortcomings of the aforementioned prior art are:

[0017] 1. Because the existing technology is based on the failure of the intake phase sensor, it does not take into account the possibility of the rail pressure sensor failure;

[0018] 2. Because the existing technology does not take into account the conversion relationship between the set flow rate of the high-pressure oil pump and the electronic pressure relief valve and the rail pressure and the fuel mass in the fuel rail, it does not estimate the rail pressure change after the high-pressure oil pump and the electronic pressure relief valve are activated, which is inaccurate;

[0019] 3. Because existing technologies are inaccurate in estimating the rail pressure changes caused by the operation of high-pressure oil pumps and electronically controlled pressure relief valves, and because there is no strategy to use estimated rail pressure as a replacement value for rail pressure after rail pressure sensor failure, they cannot be used as a solution when rail pressure is abnormal. Summary of the Invention

[0020] To address the aforementioned problems, this invention provides a control system and method for the rail pressure substitution value of a diesel engine high-pressure common rail system. Its purpose is to provide a solution when rail pressure is abnormal and to accurately estimate the rail pressure changes caused by the operation of the high-pressure oil pump and the electronically controlled pressure relief valve.

[0021] To solve the above problems, the technical solution provided by the present invention is as follows:

[0022] A control system for rail pressure substitution in a high-pressure common rail system of a diesel engine includes a hydraulic system and an electronic control system (EDC); wherein:

[0023] The hydraulic system includes a high-pressure oil rail and high-pressure oil pipes; wherein:

[0024] The electronic control system (EDC) includes sensors, the electronic control unit (ECU), actuators, and wiring harnesses; wherein:

[0025] The sensor is used to collect the operating condition information of the diesel engine in real time; the operating condition information includes vehicle speed, throttle opening, crankshaft speed, camshaft speed, and fuel rail pressure signal.

[0026] The electronic control unit (ECU) is used to receive the operating condition information of the diesel engine collected by the sensor, calculate the required fuel flow rate and injection quantity based on the operating condition information, and package the required fuel quantity and injection quantity into the control signal and send it to the actuator.

[0027] The actuator includes a high-pressure oil pump, a common rail injector, a pressure control valve, an electrically controlled pressure relief valve, a glow plug control unit, a booster pressure regulator, an exhaust gas recirculation regulator, and a throttle valve;

[0028] The common rail injector is used to atomize and distribute fuel in the combustion chamber of the diesel engine;

[0029] The high-pressure oil pump includes a fuel metering valve, which is used to compress fuel from a low-pressure state to a high-pressure state through a plunger to meet the diesel engine's requirements for fuel injection pressure and fuel injection quantity; the high-pressure oil pump is also used to control the fuel inlet quantity.

[0030] The electrically controlled pressure relief valve is used to control the oil output.

[0031] Preferably, the high-pressure fuel rail is used to store fuel and suppress pressure fluctuations caused by the high-pressure fuel pump during fuel supply and the common rail injector during fuel injection, so as to ensure the overall system pressure of the diesel engine is stable.

[0032] The high-pressure oil pump is connected to the high-pressure oil rail pipeline; the high-pressure oil pump delivers fuel that has been compressed from the low-pressure state to the high-pressure state by the plunger to the high-pressure oil rail through the pipeline.

[0033] The high-pressure fuel rail is shared and used by all cylinders of the diesel engine.

[0034] Preferably, the sensor includes a pressure sensor; the pressure sensor is used to collect the pressure signal of the oil rail in the high-pressure oil rail and provide it to the electronic control unit (ECU); the pressure sensor is installed on the high-pressure oil rail.

[0035] Preferably, a flow damper and a pressure limiter are installed on the high-pressure oil rail; wherein:

[0036] The fluid flow damper is used to cut off the fuel supply to the common rail injector when a fuel leak occurs; the fluid flow damper is also used to reduce pressure fluctuations in the common rail and the high-pressure fuel rail.

[0037] The pressure limiter is used to quickly release the pressure in the high-pressure oil rail when an abnormal pressure occurs.

[0038] Preferably, the common rail injector includes a solenoid valve; the injection timing and duration of the common rail injector are controlled by the solenoid valve; the solenoid valve controls the common rail injector according to the control signal calculated by the electronic control unit (ECU);

[0039] A control method for the rail pressure substitution value of a diesel engine high-pressure common rail system, utilizing the aforementioned control system applicable to rail pressure substitution values, comprises the following steps:

[0040] S100. Calculate the rail pressure control deviation; then execute S200.

[0041] S200. Based on the rail pressure control deviation calculated in S100, calculate the change in fuel demand within the high-pressure oil rail; then execute S300.

[0042] S300. Calculate the required fuel flow rate; then execute S400.

[0043] S400. Determine if fuel input is required; then, based on the determination result, perform the following operations:

[0044] If the determination result indicates that fuel input is required, then execute S500;

[0045] If the determination result is that no fuel input is required, then execute S600;

[0046] S500. Calculate the actual oil flow rate of the high-pressure oil pump; then execute S700.

[0047] S600. Calculate the actual oil discharge capacity of the electrically controlled pressure relief valve; then execute S700.

[0048] S700. Calculate the estimated rail pressure of the actuator after operation; then execute S800;

[0049] S800. Output the estimated rail pressure calculated in S700 as the replacement rail pressure; then end the control process applicable to the replacement rail pressure value of the high-pressure common rail system for diesel engines.

[0050] Preferably, S100 specifically includes the following steps:

[0051] S110. Obtain the current rail pressure demand;

[0052] S120. Read the estimated rail pressure from the previous cycle;

[0053] S130. Subtract the estimated rail pressure from the previous cycle read in S120 from the required rail pressure obtained in S110 to obtain the rail pressure control deviation.

[0054] Preferably, S200 specifically includes the following steps:

[0055] S210. Read the rail pressure control deviation calculated in S130;

[0056] S220. Obtain the current rail pressure;

[0057] S230. Divide the rail pressure control deviation calculated in S130 by the fuel mass-to-pressure conversion factor under the current rail pressure to obtain the change in demand for fuel within the high-pressure fuel rail; wherein:

[0058] The fuel mass-to-pressure conversion factor under the current rail pressure is expressed by the following formula:

[0059]

[0060] Where: F is the conversion factor from fuel mass to pressure under the current rail pressure; E is the bulk modulus of the liquid under the current pressure and volume; V is the sum of the volumes of the high-pressure fuel rail and the high-pressure fuel pipe; ρ1 is the fuel density under the current rail pressure.

[0061] Preferably, the fuel density under the current rail pressure mentioned in S230 is calculated according to the following steps:

[0062] Sa230. Read the current rail pressure;

[0063] Sa231. Read the current atmospheric pressure;

[0064] Sa232. Look up the table to obtain the fuel density of the fuel currently in use at the current atmospheric pressure;

[0065] Sa233. Obtain the liquid bulk modulus of the fuel currently in use under the current rail pressure by referring to the table, and take the reciprocal to obtain the compressibility coefficient of the fuel;

[0066] Sa234. Based on the current rail pressure, the current atmospheric pressure, the fuel compressibility coefficient of the currently used fuel, and the fuel density of the currently used fuel at the current atmospheric pressure, the fuel density at the current rail pressure is calculated, specifically expressed by the following formula:

[0067]

[0068] Where: ρ0 is the fuel density of the fuel currently in use at the current atmospheric pressure; K is the fuel compressibility coefficient of the fuel currently in use, which is the reciprocal of the bulk modulus E of the liquid; P0 is the current atmospheric pressure; and P1 is the current rail pressure.

[0069] Preferably, the bulk modulus of the liquid under the current pressure and volume in S230 is expressed by the following formula:

[0070]

[0071] Compared with the prior art, the present invention has the following advantages:

[0072] 1. Since this invention is designed to address the application scenario of rail pressure sensor failure, it can serve as a solution when rail pressure anomalies occur;

[0073] 2. Because this invention takes into account the conversion relationship between the set flow rate of the high-pressure oil pump and the electronically controlled pressure relief valve and the rail pressure and the fuel mass in the oil rail, it can accurately estimate the rail pressure change after the high-pressure oil pump and the electronically controlled pressure relief valve are activated. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the structure of a prior art high-pressure common rail fuel system.

[0075] Figure 2 This is a schematic diagram of the control method flow according to a specific embodiment of the present invention;

[0076] Figure 3 This is a schematic diagram of the actual rail pressure in a specific embodiment of the present invention;

[0077] Figure 4 This is a schematic diagram illustrating the estimation of rail pressure according to a specific embodiment of the present invention. Detailed Implementation

[0078] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0079] A control system for rail pressure substitution in a high-pressure common rail system of a diesel engine includes a hydraulic system and an electronic control system (EDC); wherein:

[0080] The hydraulic system includes a high-pressure oil rail and high-pressure oil pipes; among which:

[0081] Electronic control system (EDC) includes sensors, electronic control unit (ECU), actuators, and wiring harnesses; among which:

[0082] The sensor is used to collect real-time operating information of the diesel engine; the operating information includes vehicle speed, throttle opening, crankshaft speed, camshaft speed, and fuel rail pressure signal.

[0083] In this specific embodiment, the sensor includes a pressure sensor; the pressure sensor is used to collect the oil rail pressure signal in the high-pressure oil rail and provide it to the electronic control unit (ECU); the pressure sensor is installed on the high-pressure oil rail.

[0084] In this specific embodiment, the high-pressure fuel rail is used to store fuel and suppress pressure fluctuations caused by the high-pressure fuel pump during fuel supply and the common rail injector during fuel injection, so as to ensure the overall system pressure stability of the diesel engine.

[0085] In this specific embodiment, the high-pressure oil pump is connected to the high-pressure oil rail pipeline; the high-pressure oil pump delivers fuel that has been compressed from a low-pressure state to a high-pressure state through the plunger to the high-pressure oil rail through the pipeline.

[0086] In this specific embodiment, the high-pressure fuel rail is shared and used by all cylinders of the diesel engine.

[0087] In this specific embodiment, a flow damper and a pressure limiter are installed on the high-pressure oil rail; wherein:

[0088] The flow damper is used to cut off the fuel supply to the common rail injector when a fuel leak occurs; the flow damper is also used to reduce pressure fluctuations in the common rail and high-pressure rail.

[0089] It should be noted that common rail injector injection will reduce the fuel mass inside the common rail injector. Therefore, the change in fuel demand in the high-pressure fuel rail needs to be added to the fuel injection quantity to obtain the required fuel flow rate that needs to be controlled by the actuator.

[0090] The pressure limiter is used to quickly release the pressure in the high-pressure oil rail when an abnormal pressure occurs.

[0091] The electronic control unit (ECU) receives operating information about the diesel engine from sensors, calculates the required fuel flow and injection quantity based on the operating information, and packages the required fuel flow and injection quantity into a control signal to send to the actuator.

[0092] The actuator includes a high-pressure oil pump, a common rail injector, a pressure control valve, an electrically controlled pressure relief valve, a glow plug control unit, a booster pressure regulator, an exhaust gas recirculation regulator, and a throttle valve.

[0093] In this specific embodiment, the system is equipped with two actuators for rail pressure control.

[0094] It should be noted that among the two actuators used for rail pressure control, the high-pressure oil pump equipped with a fuel metering valve is used to control the fuel inlet volume, and the electronically controlled pressure relief valve is used to control the fuel outlet volume. Therefore, if the required fuel flow rate is greater than 0, that is, when fuel needs to be added to the high-pressure oil rail, the high-pressure oil pump should be controlled to achieve the required fuel inlet volume; otherwise, the electronically controlled pressure relief valve will achieve the required fuel outlet volume.

[0095] Common rail injectors are used to atomize and distribute fuel within the combustion chamber of a diesel engine.

[0096] In this specific embodiment, the common rail injector includes a solenoid valve; the injection timing and duration of the common rail injector are controlled by the solenoid valve; the solenoid valve controls the common rail injector according to the control signal calculated by the electronic control unit (ECU).

[0097] The high-pressure fuel pump includes a fuel metering valve, which compresses fuel from a low-pressure state to a high-pressure state through a plunger to meet the diesel engine's requirements for fuel injection pressure and fuel injection quantity; the high-pressure fuel pump is also used to control the fuel intake quantity.

[0098] The electrically controlled pressure relief valve is used to control the oil output.

[0099] like Figure 2 As shown, a control method for the rail pressure substitution value of a diesel engine high-pressure common rail system, utilizing the above-mentioned control system applicable to the rail pressure substitution value of a diesel engine high-pressure common rail system, includes the following steps:

[0100] S100. Calculate the rail pressure control deviation ΔP; then execute S200.

[0101] In this specific embodiment, S100 specifically includes the following steps:

[0102] S110. Obtain the current rail pressure demand.

[0103] S120. Read the estimated rail pressure from the previous cycle.

[0104] S130. Subtract the estimated rail pressure from the previous cycle read in S120 from the required rail pressure obtained in S110 to obtain the rail pressure control deviation ΔP.

[0105] It should be noted that the estimated rail pressure is the replacement rail pressure after the rail pressure sensor fails.

[0106] It should be further explained that the rail pressure control deviation ΔP is the change in the system's required rail pressure.

[0107] S200. Based on the rail pressure control deviation ΔP calculated in S100, calculate the change in fuel demand within the high-pressure oil rail; then execute S300.

[0108] In this specific embodiment, S200 specifically includes the following steps:

[0109] S210. Read the rail pressure control deviation calculated in S130.

[0110] S220. Get the current rail pressure.

[0111] S230. Divide the rail pressure control deviation calculated in S130 by the fuel mass-to-pressure conversion factor under the current rail pressure to obtain the change in demand for fuel within the high-pressure fuel rail; where:

[0112] The conversion factor from fuel mass to pressure under current rail pressure is expressed by equation (1):

[0113]

[0114] Where: F is the conversion factor from fuel mass to pressure under the current rail pressure; E is the bulk modulus of the liquid under the current pressure and volume; V is the sum of the volumes of the high-pressure fuel rail and the high-pressure fuel line; ρ1 is the fuel density under the current rail pressure.

[0115] It should be noted that the conversion factor from fuel mass to pressure under the current rail pressure is still expressed according to equation (2):

[0116]

[0117] Where: m is the mass of fuel.

[0118] It should be further noted that the conversion factor from fuel mass to pressure under the current rail pressure is still expressed according to equation (3):

[0119]

[0120] It should be further explained that the actual required control flow rate of the actuator is multiplied by the fuel mass to pressure conversion factor F to calculate the estimated rail pressure after the actuator operates.

[0121] It should be further explained that, since there is a certain delay between the calculation of the actuator's demand value and the actual change in rail pressure caused by the actuator's action, the estimated rail pressure needs to be output after a certain time delay, as a substitute rail pressure in case of rail pressure sensor failure.

[0122] In this specific embodiment, the fuel density under the current rail pressure in S230 is calculated according to the following steps:

[0123] Sa230. Read the current rail pressure.

[0124] Sa231. Read the current atmospheric pressure.

[0125] Sa232. Look up the table to obtain the fuel density of the fuel currently in use at the current atmospheric pressure.

[0126] Sa233. Look up the table to obtain the liquid bulk modulus of the fuel currently in use under the rail pressure, and take the reciprocal to obtain the compressibility coefficient of the fuel.

[0127] Sa234. Based on the current rail pressure, current atmospheric pressure, fuel compression coefficient of the fuel currently in use, and fuel density of the fuel currently in use at the current atmospheric pressure, the fuel density at the current rail pressure is calculated, specifically expressed by equation (4):

[0128]

[0129] Where: ρ0 is the fuel density of the fuel currently in use at the current atmospheric pressure; K is the fuel compression coefficient of the fuel currently in use; P0 is the current atmospheric pressure; and P1 is the current rail pressure.

[0130] It should be noted that, since the fuel compression coefficient K and the bulk modulus E of the liquid are reciprocals, the fuel density under the current rail pressure is also expressed by equation (5):

[0131]

[0132] It should be further explained that this is an empirical formula for how fuel density changes with pressure.

[0133] It should be further noted that this calculation is based on a fixed high-pressure oil rail volume.

[0134] In this specific embodiment, the bulk elastic modulus of the liquid under the current pressure and volume in S230 is expressed by equation (6):

[0135]

[0136] It should be noted that, based on the expression for the bulk elastic modulus of the liquid under the current pressure and volume, the conversion factor from fuel mass to pressure under the current rail pressure is also expressed according to equation (7):

[0137]

[0138] S300. Calculate the required fuel flow rate; then execute S400.

[0139] S400. Determine if fuel input is required; then, based on the determination result, perform the following operations:

[0140] If the determination result indicates that fuel input is required, then execute S500.

[0141] If the determination result is that no fuel input is required, then execute S600.

[0142] S500. Calculate the actual oil intake capacity of the high-pressure oil pump; then execute S700.

[0143] S600. Calculate the actual oil discharge capacity of the electrically controlled pressure relief valve; then execute S700.

[0144] It should be noted that the actuator's working capacity has physical limitations. Therefore, the required fuel flow rate needs to be limited by the actual inlet capacity of the high-pressure oil pump or the actual outlet capacity of the electronically controlled pressure relief valve before the actual required control flow rate of the actuator can be obtained.

[0145] S700. Calculate the estimated rail pressure after the actuator operates; then execute S800.

[0146] S800. Output the estimated rail pressure calculated in S700 as the replacement rail pressure; then end the control process applicable to the replacement rail pressure value of the high-pressure common rail system of diesel engine.

[0147] To further demonstrate the technical effects of the present invention, a real-world test was also conducted in this specific embodiment, as follows:

[0148] The experiment uses a six-cylinder diesel engine manufactured by the applicant as an example. For instance... Figures 3-4 The figure shows the actual rail pressure curve and the estimated rail pressure curve during operation after actively manufacturing a low rail pressure sensor voltage fault.

[0149] from Figures 3-4 It can be clearly concluded that when the rail pressure sensor fails, the system and method of this invention can accurately calculate the estimated rail pressure. The estimated rail pressure is in extremely high agreement with the actual rail pressure change trend, and the deviation from the stable operating condition is within 50 bar.

[0150] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0151] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0152] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0153] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling the rail pressure substitution value of a high-pressure common rail system for diesel engines, characterized in that: A control system suitable for rail pressure substitution values ​​in diesel engine high-pressure common rail systems is utilized; the control system includes a hydraulic system and an electronic control system (EDC); wherein: The hydraulic system includes a high-pressure oil rail and high-pressure oil pipes; wherein: The electronic control system (EDC) includes sensors, an electronic control unit (ECU), and actuators. The electronic control unit (ECU) is used to receive operating condition information about the diesel engine collected by the sensor, calculate the required fuel flow rate and injection quantity based on the operating condition information, and send the required fuel flow rate and injection quantity in a control signal to the actuator. The actuator includes a high-pressure oil pump, a common rail injector, a pressure control valve, and an electrically controlled pressure relief valve; The high-pressure oil pump includes a fuel metering valve, which is used to compress fuel from a low-pressure state to a high-pressure state through a plunger to meet the diesel engine's requirements for fuel injection pressure and fuel injection quantity; the high-pressure oil pump is also used to control the fuel inlet quantity. The electrically controlled pressure relief valve is used to control the oil output. The control method for the rail pressure substitution value applicable to the high-pressure common rail system of a diesel engine includes the following steps: S100. Calculate the rail pressure control deviation; then execute S200; S100 specifically includes the following steps: S110. Obtain the current rail pressure demand; S120. Read the estimated rail pressure from the previous cycle; S130. Subtract the estimated rail pressure from the previous cycle read in S120 from the required rail pressure obtained in S110 to obtain the rail pressure control deviation; S200. Based on the rail pressure control deviation calculated in S100, calculate the change in fuel demand within the high-pressure oil rail; then execute S300. S300. Calculate the required fuel flow rate; then execute S400; S400. Determine if fuel input is required; then, based on the determination result, perform the following operations: If the determination result indicates that fuel input is required, then execute S500; If the determination result is that no fuel input is required, then execute S600; S500. Calculate the actual oil flow rate of the high-pressure oil pump; then execute S700; S600. Calculate the actual oil discharge capacity of the electrically controlled pressure relief valve; then execute S700; S700. Calculate the estimated rail pressure of the actuator after operation; then execute S800; S800. Output the estimated rail pressure calculated in S700 as the replacement rail pressure; then end the control flow for the replacement rail pressure value applicable to the high-pressure common rail system of diesel engines.

2. The control method for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 1, characterized in that: S200 specifically includes the following steps: S210. Read the rail pressure control deviation calculated in S130; S220. Obtain the current rail pressure; S230. Divide the rail pressure control deviation calculated in S130 by the fuel mass-to-pressure conversion factor under the current rail pressure to obtain the change in demand for fuel within the high-pressure fuel rail; wherein: The fuel mass-to-pressure conversion factor under the current rail pressure is expressed by the following formula: in: The conversion factor from fuel mass to pressure under the current rail pressure; The bulk modulus of elasticity of the liquid under the current pressure and volume; The sum of the volumes of the high-pressure oil rail and the high-pressure oil pipe; The fuel density is given by the current rail pressure.

3. The control method for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 2, characterized in that: The fuel density under the current rail pressure described in S230 is calculated using the following steps: Sa230. Read the current rail pressure; Sa231. Read the current atmospheric pressure; Sa232. Look up the table to obtain the fuel density of the currently used fuel at the current atmospheric pressure; Sa233. Look up the table to obtain the liquid bulk modulus of the fuel currently in use under the rail pressure, and take the reciprocal to obtain the fuel compressibility coefficient; Sa234. Based on the current rail pressure, the current atmospheric pressure, the fuel compressibility coefficient of the currently used fuel, and the fuel density of the currently used fuel at the current atmospheric pressure, the fuel density at the current rail pressure is calculated, specifically expressed by the following formula: in: The fuel density of the fuel currently in use at the current atmospheric pressure; The compression ratio of the fuel currently in use; The current atmospheric pressure; The current rail pressure is [value].

4. The control method for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 3, characterized in that: The bulk modulus of the liquid under the current pressure and volume in S230 is expressed by the following formula: 。 5. A control system for rail pressure substitution values ​​of a diesel engine high-pressure common rail system, using the control method for rail pressure substitution values ​​of a diesel engine high-pressure common rail system according to claim 4, characterized in that: The electronic control system EDC also includes a wiring harness; The sensor is used to collect the operating condition information of the diesel engine in real time; the operating condition information includes vehicle speed, throttle opening, crankshaft speed, camshaft speed, and fuel rail pressure signal. The actuator also includes a preheating plug control unit, a booster pressure regulator, an exhaust gas recirculation regulator, and a throttle valve; The common rail injector is used to atomize and distribute fuel within the combustion chamber of the diesel engine.

6. The control system for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 5, characterized in that: The high-pressure fuel rail is used to store fuel and suppress pressure fluctuations caused by the high-pressure fuel pump during fuel supply and the common rail injector during fuel injection, so as to ensure the overall system pressure of the diesel engine is stable. The high-pressure oil pump is connected to the high-pressure oil rail via pipeline; The high-pressure oil pump delivers fuel, which has been compressed from the low-pressure state to the high-pressure state by the plunger, to the high-pressure oil rail through the pipeline; The high-pressure fuel rail is shared and used by all cylinders of the diesel engine.

7. The control system for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 6, characterized in that: The sensor includes a pressure sensor; the pressure sensor is used to collect the pressure signal of the oil rail in the high-pressure oil rail and provide it to the electronic control unit (ECU); The pressure sensor is installed on the high-pressure oil rail.

8. The control system for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 7, characterized in that: The high-pressure oil rail is equipped with a flow damper and a pressure limiter; wherein: The fluid flow damper is used to cut off the fuel supply to the common rail injector when a fuel leakage fault occurs; the fluid flow damper is also used to reduce pressure fluctuations in the high-pressure fuel rail. The pressure limiter is used to quickly release the pressure in the high-pressure oil rail when an abnormal pressure occurs.

9. The control system for rail pressure substitution value of a high-pressure common rail system for diesel engines according to claim 8, characterized in that: The common rail injector includes a solenoid valve; the injection timing and duration of the common rail injector are controlled by the solenoid valve; the solenoid valve controls the common rail injector according to the control signal calculated by the electronic control unit (ECU).

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