Diesel engine two-stage adjustable supercharging system turbine overspeed protection system

Abstract

A highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system, including an engine controller ECU, an input device, an output device, a pressure regulating device and a driving device, wherein the ECU stores a supercharger compression characteristic MAP and a supercharging system overspeed diagnosis software, the software obtains the signal collected by the input device, and judges whether the supercharging system is in an overspeed state by the pressure ratio of the two-stage supercharging system. If the system is in an overspeed state, the overspeed diagnosis software sends an overspeed signal to the ECU, and the ECU sends an instruction to the output device, and the output device executes the adjustment instruction by controlling the pressure regulating device, so that one, two or three of the diesel engine fuel injection amount, the opening of the high-pressure stage turbine bypass valve and the opening of the bleed valve are changed, and finally the pressure ratio of the supercharging system is changed, and the supercharger speed is restored to a normal state. The system has real-time monitoring, diagnosis and supercharger overspeed protection functions, and can make the two-stage supercharging system operate normally under different working conditions and different geographical conditions.

Description

Technical Field

[0001] The invention belongs to the field of vehicle system control and relates to an overspeed protection system of a two-stage adjustable supercharging system of a plateau electronically controlled diesel engine. Background Art

[0002] The two-stage turbocharger system is a new technology in automotive diesel engines. The diesel engine exhaust gas expands and works in the high-pressure and low-pressure turbines in turn. The rotation of the turbine drives the coaxial high-pressure and low-pressure compressors to compress the air. Compared with the single-stage turbocharger, the pressure and flow of the air after being compressed by the two-stage compressor are significantly improved, which can effectively improve the combustion process of the diesel engine under various working conditions. It is of great significance to improve the power of the diesel engine, reduce fuel consumption, increase power and improve emissions. However, in high-altitude areas, due to the decrease in air density, the decrease in excess air coefficient, the excessive richness of the combustible mixture, the longer ignition delay period, and the serious afterburning phenomenon, the diesel engine exhaust energy increases, the turbocharger speed increases, and the compressor overspeed phenomenon is more likely to occur at high speed and high load than on the plain. Turbocharger overspeed will cause the combustion pressure and combustion temperature in the engine cylinder to be too high, affecting the life and performance of the diesel engine, and at the same time bringing challenges to the working stability and safety of the diesel engine. Summary of the invention

[0003] The purpose of the present invention is to provide an overspeed protection system for a two-stage adjustable supercharging system of a plateau electronically controlled diesel engine, which has real-time monitoring, diagnosis and supercharger overspeed protection functions, and can enable the two-stage supercharging system to operate normally under different working conditions and different geographical conditions.

[0004] As conceived above, the technical solution of the present invention is: a high-altitude electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system, including an engine controller ECU, an input device, an output device, a pressure regulating device and a driving device, the engine controller ECU stores the supercharger compression characteristic MAP, the input device includes a high-pressure compressor inlet pressure sensor, a high-pressure compressor outlet pressure sensor, an atmospheric pressure sensor, a low-pressure outlet pressure sensor, a high-pressure turbine bypass valve opening detector, a low-pressure turbine bleed valve opening detector, an intake flow sensor, and an engine speed sensor, the output device includes a turbine bypass valve controller, a bleed valve opening controller and an injector, the pressure regulating device includes a high-pressure turbine bypass valve, a low-pressure turbine bleed valve and an injection pump nozzle, the The driving device is one or two of a gear pump, a plunger pump, and a vane pump; the characteristic is that: the engine controller ECU stores the supercharging system overspeed diagnosis software, the software obtains the signal collected by the input device, and judges whether the supercharging system is in an overspeed state through the pressure ratio of the secondary supercharging system. The supercharger pressure ratio is associated with the supercharger speed through the supercharger boost characteristic MAP. If the system is in an overspeed state, the overspeed diagnosis software sends an overspeed signal to the engine controller ECU, and the engine controller ECU sends an adjustment instruction to the output device. The output device executes the adjustment instruction by controlling the pressure adjustment device, so that one, two or three of the diesel engine injection amount, the high-pressure stage turbine bypass valve opening and the bleed valve opening are changed, and finally the pressure ratio of the supercharging system is changed, and the supercharger speed is restored to a normal state.

[0005] Furthermore, the engine controller ECU stores a table of opening adjustment coefficients of the overspeed bypass valve / bleed valve of the high-pressure and low-pressure stage superchargers.

[0006] Furthermore, the first, second and third thresholds are calibrated in the supercharger boost characteristic MAP, wherein the first threshold is the overspeed pressure ratio of the two-stage supercharging system corresponding to the current speed, the second threshold is the corresponding pressure ratio of the two-stage supercharging system in a severe overspeed condition, and the third threshold is the corresponding pressure ratio when the high-pressure stage supercharger is in an overspeed condition, and the definition is the same as the second threshold.

[0007] Furthermore, the method for obtaining the first threshold is: the overspeed diagnosis software obtains the intake flow rate and the pressure ratio of the high- and low-pressure stage superchargers of the current two-stage supercharging system, queries the supercharger compression characteristic MAP to obtain the overspeed pressure ratio of the high- and low-pressure stage superchargers under the current operating conditions, and multiplies them to obtain the overspeed pressure ratio of the two-stage supercharging system.

[0008] Furthermore, the method for obtaining the second threshold value is: the overspeed diagnostic software obtains the flow rate of the current two-stage supercharging system and the pressure ratio of the high- and low-pressure stage superchargers, queries the supercharger compression characteristic MAP to obtain the pressure ratio of the high- and low-pressure stage superchargers under the current operating conditions, and the severe overspeed pressure ratio is defined as when the supercharger overspeed is greater than a certain value, the pressure ratio of the turbine bypass valve or the bleed valve adjustment coefficient is greater than 1.4 when the supercharger speed returns to normal state. If the high- and low-pressure stage superchargers are in a severe overspeed state at this time, then the pressure ratio of the two-stage supercharging system at this time is a severe overspeed pressure ratio.

[0009] The present invention has the following advantages: the turbine bypass valve / bleed valve is the final executive component for adjusting the boost pressure of the supercharging system and the supercharger speed, and the supercharger speed is a variable that needs to be controlled and detected in the overspeed protection system. The valve opening is associated with the supercharger speed, and the system forms a closed-loop control. The present invention utilizes the supercharger overspeed bypass valve / bleed valve opening adjustment coefficient table to quickly and accurately control the supercharger speed, minimize the power loss and equipment loss of the two-stage supercharging system due to overspeed, improve the operating efficiency of the two-stage supercharging system under all working conditions, extend the service life of the supercharging system, and enhance the safety and reliability of diesel engine operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a common diesel engine two-stage supercharging system structure diagram;

[0011] Figure 2 It is the control flow chart of the supercharging system overspeed diagnosis software;

[0012] Figure 3 is a boost characteristic MAP diagram of the supercharger of the present invention;

[0013] Figure 4 It is the opening adjustment coefficient table of the overspeed bypass valve of the high-pressure stage supercharger;

[0014] Figure 5 It is the low-pressure stage supercharger overspeed bleed valve opening adjustment coefficient table.

[0015] In the figure: 1-bypass valve opening sensor; 2-bleed valve opening sensor; 3-low-pressure stage turbine; 4-high-pressure stage turbine; 5-Ⅰ-stage intercooler; 6-high-pressure stage compressor outlet pressure sensor; 7-high-pressure stage compressor; 8-high-pressure stage compressor inlet pressure sensor; 9-Ⅱ-stage intercooler; 10-low-pressure stage compressor outlet pressure sensor; 11-low-pressure stage compressor; 12-atmospheric pressure sensor; 13-intake air flow sensor; 14-engine speed sensor. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the accompanying drawings and control strategies.

[0017] like Figure 1-4 As shown: The present invention provides an overspeed protection system for a two-stage adjustable supercharging system of a plateau electronically controlled diesel engine, which consists of a two-stage supercharging system of a diesel engine and overspeed diagnostic software for the supercharging system.

[0018] like Figure 1 As shown: The diesel engine two-stage supercharging system includes an engine controller ECU, an input device, an output device, a pressure regulating device, and a driving device.

[0019] The input device includes a high-pressure compressor inlet pressure sensor, a high-pressure compressor outlet pressure sensor, an atmospheric pressure sensor, a low-pressure outlet pressure sensor, a high-pressure turbine bypass valve opening detector, a low-pressure turbine bleed valve opening detector, an intake flow sensor, and an engine speed sensor;

[0020] The output device includes a turbine bypass valve controller, a bleed valve opening controller and a fuel injector. The bypass valve / bleed valve opening controller adopts a PID control principle and is adjusted according to the difference between the target value and the actual value.

[0021] The pressure regulating device comprises a high-pressure stage turbine bypass valve, a low-pressure stage turbine bleed valve and a fuel injection pump nozzle;

[0022] The driving device is one or two of a gear pump, a plunger pump and a vane pump.

[0023] like Figure 2-4 As shown: the supercharger compression characteristic MAP and the supercharging system overspeed diagnosis software are stored in the engine controller ECU. The supercharger compression characteristic MAP is provided by the supercharger manufacturer. At the same time, the first, second and third thresholds are calibrated in the supercharger boost characteristic MAP.

[0024] The high- and low-pressure stage supercharger overspeed operating condition valve adjustment coefficient table is based on the two-stage adjustable supercharging system adjustment characteristic test bench. The two-stage adjustable supercharging system adjustment characteristic test is carried out to explore the overspeed adjustment ability of the high-stage turbine bypass valve and the low-pressure stage turbine bleed valve under different intake flow rates and boost pressures. Based on this, the adjustment coefficients of the bypass valve and bleed valve openings under different overspeed conditions are determined. In the diesel engine two-stage adjustable supercharging system overspeed protection system, the high- and low-pressure stage supercharger overspeed operating condition valve adjustment coefficient table is stored in the engine controller ECU.

[0025] Among them, the first threshold is the overspeed pressure ratio of the two-stage supercharging system corresponding to the current speed. The diagnostic module obtains the flow rate and the pressure ratio of the high- and low-pressure stage superchargers of the current two-stage supercharging system, queries the compressor boost characteristic MAP to obtain the overspeed pressure ratio of the high- and low-pressure stage superchargers under the current operating conditions, and the multiplication is the overspeed pressure ratio of the two-stage supercharging system.

[0026] The second threshold is the pressure ratio corresponding to the severe overspeed condition of the two-stage supercharging system. The diagnostic module obtains the flow rate of the current two-stage supercharging system and the pressure ratio of the high- and low-pressure stage superchargers, and queries the compressor boost characteristic MAP to obtain the pressure ratio of the high- and low-pressure stage superchargers under the current operating conditions. The severe overspeed pressure ratio is defined as the pressure ratio when the turbocharger overspeed is greater than a certain value and the turbocharger speed returns to normal, and the turbine bypass valve or bleed valve adjustment coefficient is greater than 1.4. If the high- and low-pressure stage superchargers are in a severe overspeed state at this time, the pressure ratio of the two-stage supercharging system at this time is the severe overspeed pressure ratio.

[0027] The third threshold is the pressure ratio when the high-pressure stage supercharger is in a severe overspeed condition, and its definition is the same as the second threshold.

[0028] The operation method of the present invention is:

[0029] The supercharging system overspeed diagnostic software obtains the signals transmitted by the input device including the atmospheric pressure and the high-pressure compressor outlet pressure, calculates the total pressure ratio of the current two-stage supercharging system, and obtains the current supercharging system intake flow rate at the same time. The pressure ratio and intake flow rate are used to query the supercharger compression characteristic MAP stored in the controller, and compare the current supercharging system pressure ratio with the first threshold value. If the current pressure ratio is greater than the first threshold value, it is determined to be overspeed. If the current pressure ratio is less than the first threshold value, it returns to continue to execute the previous process. When the overspeed diagnostic software determines that the supercharging system is in an overspeed condition, it will compare the system pressure ratio with the second threshold value. If the pressure ratio is greater than the second threshold value, it is determined to be a serious overspeed. The diagnostic module sends a serious overspeed signal to the controller, and the controller sends a fuel limit instruction to the output device. Then the injector controls the injection pump nozzle to execute the decision to adjust and reduce the injection amount. If the system pressure ratio is less than the second threshold, the overspeed diagnostic software obtains the high-pressure stage boost pressure through the input device, and converts the high-pressure stage pressure ratio and intake flow rate into the pressure ratio and intake flow rate under plain conditions, queries the compressor boost characteristic MAP to obtain the supercharger speed, and determines whether the high-pressure stage supercharger is overspeeding. If it is overspeeding, the overspeed amount will be calculated, and it will be determined whether the overspeed amount is greater than the third threshold. If the overspeed amount is greater than the third threshold, it is determined that the high-pressure stage supercharger is in serious overspeeding, and the diagnostic module sends a serious overspeed signal to the controller, and the controller sends a fuel limit instruction to the output device, and the injector controls the injection pump nozzle to perform the adjustment to reduce the injection amount; if the overspeed amount is less than the third threshold, the overspeed diagnostic software calls the high-pressure stage supercharger overspeed bypass valve opening adjustment coefficient table stored in the controller, and queries the opening adjustment value according to the table according to the current speed and overspeed amount, and obtains the bypass valve adjustment opening from the table, and inputs the adjustment opening into the controller, and the controller sends the adjustment instruction to the output device, and the bypass valve opening controller executes the decision of the valve opening change. If the high-pressure stage supercharger is not overspeeding, the overspeed diagnosis software obtains the atmospheric pressure and the low-pressure stage compressor outlet pressure, calculates the low-pressure stage supercharger pressure ratio, converts the low-pressure stage supercharger pressure ratio and intake flow rate into the pressure ratio and intake flow rate under plain conditions, obtains the supercharger speed by querying the low-pressure stage compressor boost characteristic MAP, and calculates the overspeed of the low-pressure stage supercharger, based on the overspeed and the current engine speed, queries the low-pressure stage supercharger overspeed condition bleed valve opening adjustment coefficient table, obtains the bleed valve opening adjustment value, sends the bleed valve opening adjustment value to the controller, the controller sends the bleed valve adjustment instruction to the output device, and the bleed valve opening controller executes the opening change.

[0030] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system, comprising an engine controller ECU, an input device, an output device, a pressure regulating device and a driving device, wherein the engine controller ECU stores a supercharger compression characteristic MAP, the input device comprises a high-pressure compressor inlet pressure sensor, a high-pressure compressor outlet pressure sensor, an atmospheric pressure sensor, a low-pressure outlet pressure sensor, a high-pressure turbine bypass valve opening detector, a low-pressure turbine bleed valve opening detector, an intake flow sensor, and an engine speed sensor, the output device comprises a turbine bypass valve controller, a bleed valve opening controller and an injector, the pressure regulating device comprises a high-pressure turbine bypass valve, a low-pressure turbine bleed valve and an injection pump nozzle, and the driving device is one or two of a gear pump, a plunger pump and a vane pump; characterized in that: The engine controller ECU stores supercharging system overspeed diagnostic software, which obtains signals collected by the input device, and determines whether the supercharging system is in an overspeed state through the pressure ratio of the secondary supercharging system. The supercharger pressure ratio is associated with the supercharger speed through the supercharger boost characteristic MAP. If the system is in an overspeed state, the overspeed diagnostic software sends an overspeed signal to the engine controller ECU, and the engine controller ECU sends an adjustment instruction to the output device. The output device executes the adjustment instruction by controlling the pressure adjustment device to change one, two or three of the diesel engine injection amount, the high-pressure stage turbine bypass valve opening and the bleed valve opening, thereby finally changing the pressure ratio of the supercharging system and restoring the supercharger speed to a normal state.

2. The highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system according to claim 1 is characterized by: The engine controller ECU stores a high-pressure and low-pressure stage supercharger overspeed bypass valve / bleed valve opening adjustment coefficient table.

3. The highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system according to claim 1 is characterized by: The first, second and third thresholds are calibrated in the supercharger boost characteristic MAP, wherein the first threshold is the corresponding overspeed pressure ratio of the two-stage supercharging system at the current speed, the second threshold is the corresponding pressure ratio of the two-stage supercharging system in a severe overspeed condition, and the third threshold is the corresponding pressure ratio when the high-pressure stage supercharger is in an overspeed condition, and the definition is the same as the second threshold.

4. The highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system according to claim 3 is characterized by: The method for obtaining the first threshold is: the overspeed diagnosis software obtains the intake flow rate and the pressure ratio of the high- and low-pressure stage superchargers of the current two-stage supercharging system, queries the supercharger compression characteristic MAP to obtain the overspeed pressure ratio of the high- and low-pressure stage superchargers under the current operating conditions, and multiplies them to obtain the overspeed pressure ratio of the two-stage supercharging system.

5. The highland electronically controlled diesel engine two-stage adjustable supercharging system overspeed protection system according to claim 3 is characterized by: The method for obtaining the second threshold value is: the overspeed diagnosis software obtains the flow rate of the current two-stage supercharging system and the pressure ratio of the high- and low-pressure stage superchargers, and queries the supercharger compression characteristic MAP to obtain the pressure ratio of the high- and low-pressure stage superchargers under the current working conditions. The severe overspeed pressure ratio is defined as the pressure ratio when the turbocharger overspeed is greater than a certain value, and the turbocharger speed returns to normal state, and the turbine bypass valve or the bleed valve adjustment coefficient is greater than 1.

4. If the high- and low-pressure stage superchargers are in a severe overspeed state at this time, then the pressure ratio of the two-stage supercharging system at this time is a severe overspeed pressure ratio.

Images