MXPA01005718A - System and method for controlling a sequential turbocharging system - Google Patents

Abstract

A method for controlling an internal combustion engine (62) with a sequential turbocharging system (60) which limits an applied engine torque (80) to a dynamic engine torque limit value (74) to achieve increased turbocharger shaft acceleration during the presence of a mode switch pending condition (92). The presence of the mode switch pending condition (92) indicates that the sequential turbocharging system (60) is operating in the first mode, in which the primary turbocharger (52) is active, and it is desired to operate the system (60) in the second mode, in which both the primary and secondary turbochargers (52, 54) are active.

Description

SYSTEM AND METHOD FOR CONTROLLING A SEQUENTIAL TURBOCHARGING SYSTEM Technical Field The present invention relates to systems and methods for controlling an internal combustion engine with a sequential turbo charge system. Prior Technique In the control of internal combustion engines, conventional practice uses electronic control units that have volatile and non-volatile memory, power and output controller circuits and a processor capable of executing a set of stored instructions, to control the various functions of the engine and its associated systems. A particular electronic control unit communicates with numerous detectors, actuators and other electronic control units, to control various functions that may include various aspects of fuel supply, transmission control, sequential turbocharging system control or many others. A turbo charger consists of a turbine and a compressor. The exhaust gas pressure of the engine causes the turbine to rotate. The turbine displaces the compressor, which is typically mounted on the same arrow.

The rotary compressor creates turbo boost pressure that develops increased power during combustion. A scrap gate on the turbine inlet limits the amount of boost pressure, to protect the engine components and turbo charger. When the boost pressure reaches a predetermined value, the waste gate opens to provide a bypass for a portion of the exhaust gases that pass directly to the exhaust manifold. In a sequential charge turbo system, a plurality of turbochargers are provided. The motor controller activates the turbo chargers as required, based on the operating conditions of the motor. One form of a sequential charge turbo system is the dual turbo charging system where a primary turbo charger is always active and where a secondary turbo charger is selectively activated by the motor controller, as required. One use for sequential dual turbo charging systems is in marine engines. Although existing sequential turbo charging systems, including dual-type sequential turbo charging systems, have been employed in many applications that have been commercially successful, existing systems have some disadvantages. In very heavy boats, such as sport fishing, where a significant amount of load on the engines during acceleration, the change from simple turbo mode to dual turbo mode can sometimes overload the engine from which it can not recover. The engine then has to switch back to simple turbo mode to rebuild its boost pressure and accelerate. This overload when switching to dual turbo mode of the single turbo mode can happen several times before the system can finally remain in dual turbo mode. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an improved system and method for controlling a sequential turbo charge system that limits the applied torque of the motor to control the turbocharger's arrow speed, while the arrow speed is controlled in order to achieve a significantly higher arrow acceleration during a condition pending switching of the turbo charger mode. To carry out the above objective and other objects and features of the present invention, a method for controlling an internal combustion engine with a sequential turbo charge system is provided. The sequential turbo charging system includes a primary turbo charger and a secondary turbo charger. The sequential turbo charging system is capable of operating in a first mode, where the primary turbocharger is active while the secondary turbocharger is inactive. The sequential turbo charging system is also capable of operating in a second mode, where both the primary turbo charger and the secondary turbo charger are active. The method comprises determining the presence or absence of a pending mode switching condition, wherein the sequential turbo charging system is operating in the first mode and it is desired to operate the sequential turbo charging system in the second mode. A limit value of turbocharger arrow speed based on the presence or absence of the mode switching pending condition is determined. The primary turbocharger is checked to determine a current value for a primary turbocharger arrow speed. An error signal based on the current value for the arrow speed of the primary turbocharger and the turbocharger arrow speed limit value is determined. A limit value of torque for the dynamic motor based on the error signal is determined. A torque limit value of the dynamic motor is determined in order to track the current value for the speed of the arrow of the primary turbocharger to the turbocharger arrow speed limit value, when the motor torque applied is the torque limit value of the dynamic motor. The method further comprises limiting the motor torque applied to the limiting value of the dynamic motor torque. The limit value of the turbocharger arrow speed during the presence of a mode switching pending condition significantly exceeds the turbocharger arrow speed limit during the absence of the mode switching pending condition, such that the presence of the mode switching pending condition results in a significantly increased error signal. The increased error signal results in a significantly increased dynamic motor torque limit value. Advantageously, an increased turbocharger arrow acceleration is achieved when a turbo charger mode switch is pending, which reduces the likelihood of motor overloading upon activation of the secondary turbo charger. Preferably, the limit value of the turbocharger arrow speed is based on the engine speed. In addition, to carry out the present invention, a control system for regulating an internal combustion engine with a sequential turbo charge system is provided. The control system comprises a detection device for verifying the primary turbocharger, to determine a current value for an arrow speed of primary turbo charger. The control system further comprises control logic to determine the presence or absence of a pending mode switching condition, to determine a turbocharger arrow speed limit value, to determine an error signal, to determine a limit value of torque of dynamic motor, and to limit a torque of motor applied to the limit value of dynamic motor torque. The limit value of the turbocharger arrow speed during the presence of the mode switching pending condition significantly exceeds the turbocharger arrow speed limit value during the absence of the mode switching pending condition. As such, a mode switching pending condition results in a significantly increased error value, resulting in a significantly increased dynamic motor torque limit value. Still further, to carry out the present invention, a computer-readable storage medium is provided. The computer-readable storage medium has stored information representing instructions, which are executed by an engine controller, to control a vehicle that has an internal combustion engine with a sequential turbo charge system. The computer readable storage medium further comprises instructions for determining the presence or absence of a condition pending switching mode, instructions for determining a turbocharger arrow speed limit value, instructions for checking the primary turbocharger and instructions for determining an error signal. The computer-readable storage medium further comprises instructions for determining a limit value of dynamic motor torque, and instructions for limiting a torque of a motor applied to the limit value of dynamic motor torque. The turbocharger arrow speed limit value during the presence of the mode switching pending condition significantly exceeds the limit value of the turbocharger arrow speed during the absence of the mode switching pending condition. As such, a condition pending mode switching results in a significantly increased error signal, resulting in a significantly increased dynamic motor torque limit value. The advantages associated with embodiments of the present invention are numerous. For example, systems and methods of the present invention are capable of effectively limiting the final torque, to maintain the looper tube arrow speed, while significantly increased turbocharger arrow acceleration is achieved when a pending condition of the loader tube is present. mode switching. The increased arrow acceleration reduces the probability of overloading the engine and significantly loosens boost pressure when activated by the secondary turbo charger. The foregoing objects and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention, when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 in a schematic diagram of a control system, to control an internal combustion engine with a sequential charge turbo system; Figure 2 is a block diagram of a closed-loop or closed-loop control system of the present invention, which determines the limit value of dynamic motor torque, based on a turbine speed error signal; and Figure 3 is a block diagram illustrating a method of the present invention for controlling an internal combustion engine with a sequential turbo charge system. BEST MODE FOR CARRYING OUT THE INVENTION Now with reference to Figure 1, a system for controlling a turbocharging system is illustrated sequentially. The system, generally indicated by reference numeral 10, includes a motor 12 having a plurality of cylinders, each powered by fuel injectors 14. In a preferred embodiment, the engine 12 is a compression ignition internal combustion engine. , such as a 4, 6, 8, 12, 16 or 24 cylinder diesel engine, or a diesel engine having any other number of cylinders desired. Fuel injectors 14 receive pressurized fuel from a supply connected to one or more high or low pressure pumps (not shown) as is well known in the art. Alternatively, embodiments of the present invention may employ a plurality of unitary pumps (not shown), each pump supplies fuel to one of the injectors 14. The system 10 includes a sequential turbo charging system 50, for directing air to the cylinders to create increased power during combustion. The sequential turbo charge system 50 is a dual turbocharged system that includes a primary turbo charger 52 and a secondary turbo charger 54. The engine exhaust is directed to the turbine inlets of the turbo charger on lines 56. The air directed to the intake of the engine air is sent through the compressors and to the motor through lines for air inlet 58. It should be understood that the dual sequential turbo charge system is shown for illustration purposes and that systems and methods of the present invention can be used in a turbo charge system, muiti turbo, to assist any switching mode in which an additional turbocharger is activated. That is, the term "first mode" as used herein means any mode of operation that has fewer active turbochargers than is understood by "second mode" as used herein. In addition, term "primary loader turbo" as used herein, means a single or a set of turbo loaders that are active when operating in the "first mode"; and the term "secondary charger turbo" as used herein means a single or a set of turbo chargers that are inactive in the "first mode" and are active before transmission to the "second mode". As such, a person of ordinary skill in the art appreciates the broad applicability of the teachings of the present invention in the technique of sequential turbo charging systems, of which a dual type system is simply exemplary, and is debed herein to facilitate a compression of the present invention. The system 10 may also include various detectors 20, to generate signals indicative of the corresponding operating conditions or parameters of the engine 12, the vehicle transmission (not shown), turbocharging system 50 and other vehicular components. The sensors 20 are in electrical communication with a controller 22 via power gates 24. The controller 22 preferably includes a microprocessor 26 in communication with various computer readable media 28 via the data and control duct 30.

Computer-readable storage means 28 can include any of a number of known devices that function as a read-only memory (ROM = Read-Only-Memory) 32, random access memory (RAM = Random Access Memory) 34, active maintenance memory (KAM = Keep Alive Memory) 36 and the like. The computer readable storage media can be implemented by any number of known physical devices capable of storing data representing instructions executable by a computer such as a controller 22. Known devices may include, but are not limited to, PROM, EPROM, EEPROM, flash memory and the like, as well as magnetic, optical and combination media, capable of storing data temporarily or permanently. Computer-readable storage means 28 implement logic control by software, micro codes and / or circuits to effect control of various vehicle systems and sub-systems, such as the engine 12, a vehicle transmission (not shown), Turbo charge 50 and similar. The controller 22 receives signals from the detectors 20 via feed gates 24 and generates output signals that can be provided to various stationary and / or components by output gates 38. Signals can also be provided to an display device 40 that includes various indicators such as lamps 42, to communicate information regarding system operation to the vehicle operator. A data interface, diagnostics and programming 44 can also be selectively connected to the controller 22 via an outlet 46 for exchanging various information. The interface 44 can be used to change values within the computer readable storage means 28, such as configuration settings, calibration variables, fault threshold values, control logic and the like including limit value maps for arrow speed of turbo charger, which are preferably implemented as search tables. In operation, the controller 22 receives signals from the detectors 20 and executes control logic to control the turbocharger arrow speed primary by limiting the final or applied torque. In addition, the controller 22 executes control logic, to achieve significantly increased primary turbocharger arrow acceleration when a pending turbo charger mode switching condition is present, by increasing the turbocharger arrow speed limit value. Increased turbo charger arrow acceleration decreases the probability of engine overload and loss of boost pressure to a point that can not be recovered when the system activates the secondary turbocharger by opening additional escape passages that were previously closed. In a preferred embodiment, controller 22 is the DDEC controller available from the Detroit Diesel Corporation, Detroit, Michigan. Various other features of this controller are described in detail in U.S. Pat. Nos. 5,477,827 and 5,445,128, the descriptions of which are hereby incorporated by reference in their entirety. With continued reference to Figure 1, a logic controller such as the microprocessor 26 controls the signals that are sent to the fuel injectors 14. The microprocessor 26 calculates a provisional or desired torque based on the operator's demand and current operating conditions. The provisional motor torque can be limited to a dynamic motor torque limit value according to the present invention. The signals that are sent to the fuel injectors 14 are then based on the applied engine torque (after limitation of torque, when appropriate). In the sequential loader turbo system 50, the microprocessor 26 determines the operating mode of the turbocharger system such as, for example, a turbo single or multiple turbo mode. The selection of turbo mode and dynamic torque limitation can be included in the functions of the microprocessor 26, or can be implemented in any other way known in the art of control systems of hardware and software, including an independent control unit that is in communication with the controller 22 for control of the turbocharger. As will be appreciated by a person of ordinary skill in the art, control logic can be implemented or implemented in hardware, software or a combination of hardware and software. The various functions of preference are effected by a programmable microprocessor, such as the DDEC controller, but may include one or more functions implemented by dedicated electrical, electronic or integrated circuits. As will also be appreciated, the control logic can be implemented using any of a number of known programming and processing techniques or strategies and is not limited to the order or sequence illustrated here for convenience. For example, event-shifted processing or interruption is typically employed in real-time control applications, such as transmission control or a vehicle's engine. Likewise, systems and methods of parallel processing or multiple tasks can be used to achieve the objectives, characteristics and advantages of the present invention. The present invention is independent of the particular programming language, operating system or processor used to implement the illustrated control logic. With reference to Figure 2, a dynamic motor torque limit value, is used to control the final or applied torque, to maintain turbocharger arrow speed; and as desired, the dynamic motor torque limit value is controlled to achieve rapid acceleration of the turbo charger shaft, when a condition pending mode switching is present. The torque limit is determined, preferably based on a closed-loop control system, generally indicated at 60. In a closed-loop control system 60, the motor 62 is the plant, at which the current value for the turbocharger arrow speed primary charger is measured. The measured primary turbocharger arrow speed 64 is a feed to an adder 66 at the negative terminal. A turbocharger arrow speed limit value 68 is fed to the positive terminal of the adder 66. The limit value of the turbocharger arrow speed is determined based on the presence or absence of a pending mode switching condition. More particularly, during the absence of the pending mode switching condition, the turbocharger arrow speed limit value is set to a value sufficient for normal motor operation. During the presence of a condition pending mode switching, the limit value of the turbocharger arrow speed is set to a value that exceeds the turbocharger arrow speed limit values during normal operation. The limit value in the presence of a mode switching pending condition exceeds the limit value during the absence of the mode switching pending condition by an amount sufficient to achieve the desired increased acceleration of the turbo charger arrow. That is, the turbocharger arrow speed limit value is based on engine conditions, including the presence or absence of the mode switching pending condition. During development, the inventor has found that for any particular internal combustion engine by a sequential turbo charging system, the turbocharger arrow speed limit values at different engine conditions are best found either by empirical or current test. A convenient way to implement the turbo charger arrow speed limit values to the control system is with a look-up table accessible by the motor controller. An error signal 69 at the output of the adder 66 is based on the actual value 64 for the primary turbocharger arrow speed and the limit value of the turbocharger arrow speed 68. Although the error signal 69 is illustrated as a direct sum of reference and current values for turbo speed, other methods for generating an error signal may be convenient, as will be appreciated by a person with ordinary skill in the specialty of tracking control systems such as closed loop systems . A controller 70 is a convenient way to process error signal 69, to obtain a useful signal to the motor 62. The controller 70 preferably includes a proportional component and an integral component set forth in block 72. The error signal 69 feeds through the proportional and integral term 72 to produce the dynamic motor torque limit 74. Of course, it will be appreciated that the use of proportional and integral terms is a convenient technique for determining the limit of dynamic motor torque 74 and other techniques can be employed to determine the dynamic torque limit, such that the measured turbo speed 64 can track the turbo speed 68. A provisional torque 76 is supplied by the motor controller (22). ), Figure 1. A limiter 78 limits an applied torque of motor 80 to the limiting value of the dynamic motor torque 74. As such, e The closed circuit control system 60, effectively tracks the turbo speed measured 64 to the turbo speed limit 68, when the torque limiter 68 is active. It is preferred that the limiter 78 always be active during motor accelerations, such that the applied torque 80 is always limited to the limit of dynamic motor torque 74 ( during engine accelerations). As such, increased turbo charger arrow acceleration is achieved by increasing the value of the turbo speed limit 68 according to the present invention, when a condition pending mode switching is present. That is, in operation, the measured turbo speed 64 approaches the turbo speed limit 68 in a controlled manner due to the controller 70. When a rapid increase in the looper tube speed acceleration is desired, the the turbocharger arrow speed limit value 68 according to the present invention, allowing the controller 70 to respond rapidly by increasing the torque limit 74, resulting in a significantly increased applied torque of 80. It will be appreciated that the Closed loop control system 60 may also be employed, as desired to avoid excessive speed of the turbo charger shaft. But it will be appreciated that an object of the present invention is to control a turbocharger to achieve rapid arrow acceleration before a switching mode without necessarily considering the speed of the turbocharger's arrow. With reference to Figure 3, a method of the present invention for controlling an internal combustion engine with a turbocharging sequential system is generally indicated at 90. In block 92, the presence or absence of a pending switching condition of node, it is determined. In block 94, a turbocharger arrow speed limit value is determined, based on the presence or absence of the mode switching pending condition. Preferably, the limit value of the arrow speed of the turbo charger is further based on engine conditions including engine rpm. In block 96, the primary turbocharger is checked to determine a current value for the arrow speed of the primary turbo charger. Of course, as previously mentioned, the term "primary turbo charger" can mean a group of turbochargers that are active in the "first mode" of the system operation. In this mode, the verification of the arrow speed of the "primary loader turbo" can be performed by checking the speed of the arrow of any of the active turbo chargers in the first mode or by determining an average arrow speed or any other technique that It will be appreciated by a person with ordinary skill in the specialty.

In block 98 an error signal is determined. The error signal is based on the current value for the arrow speed of the primary turbocharger and the limit value of the turbocharger arrow speed. In block 100, the limiting value of the dynamic motor torque is determined. The limit value is based on the error signal in order to track the current value for the arrow speed of the primary turbocharger to the turbocharger arrow speed limit value. In block 102, the torque of the applied motor is reduced to the limit value of dynamic motor torque. It will be appreciated that the torque limit value of the dynamic motor varies based on the limit value of the arrow speed of the turbo charger. Accordingly, the torque limit of the dynamic motor is higher during the presence of a mode switching pending condition than during the absence of a mode switching pending condition. As such, the presence of a pending mode switching condition results in a significantly increased error signal, resulting in a significantly increased dynamic motor torque limit value. Of course, it will be appreciated that the relative values of the torque limit during the presence or absence of a mode switching pending condition only requires deferring by an amount sufficient to cause the desired increase in arrow acceleration of the turbo charger. As such, the amount of arrow acceleration desired prior to mode switching can vary from engine to engine, and an appropriate arrow acceleration for a particular engine can be formed by motorcycle test, as appreciated by a person with ordinary skill in the specialty. While the best mode contemplated for carrying out the invention has been described in detail, those familiar with the technique to which this invention relates will recognize various alternate designs and embodiments for practicing the invention as defined by the following claims.

Claims (9)

1. CLAIMS 1.- A method to control an internal combustion engine with a sequential turbo charging system, the sequential turbo charging system includes a primary turbo charger and a secondary turbo charger and which is capable of operating in a first mode where the turbo charger primary is active while the secondary turbocharger is inactive and is also able to operate in a second mode, in which both the turbocharged primary turbo charger and secondary are active, the method is characterized because it includes: determining the presence or absence of a condition pending switching mode in which the sequential turbo charging system operates in the first mode and it is desired to operate the sequential turbo charging system in the second mode; determine the turbocharger arrow speed limit value based on the presence or absence of the mode switching pending condition; verify the primary turbo charger to determine a current value for a turbocharger arrow speed primary; determining an error signal based on the current value for the turbocharger arrow speed primary and the turbocharger arrow speed limit value; determining a dynamic motor torque limit value based on the error signal in order to track the current value for the primary turbocharger arrow speed to the turbocharger arrow speed limit value; and limiting a motor torque applied to the dynamic motor torque limit value, wherein the turbocharger arrow speed limit value during the presence of the mode switching slope condition significantly exceeds the speed limit of turbo charger arrow during the absence of the mode switching pending condition, such that the presence of the mode switching pending condition results in a significantly increased error signal, resulting in a torque limit value of dynamic motor, significantly increased.
2. 2. - The method according to claim 1, characterized in that the determination of the speed limit value of the turbo charger also includes: determining the limit value of turbocharger arrow speed based on the speed of the engine.
3. 3. The method according to claim 1, characterized in that it also comprises switching the system mode of sequential charge turbo from the first mode to the second mode, so that both the primary turbo charger and the secondary turbo charger are inactive .
4. 4. - A control system for an internal combustion engine with a sequential turbo charging system, the sequential turbo charging system includes a primary turbo charger and a secondary turbo charger, and which is capable of operating in a first mode, wherein the primary turbo charger is active while the secondary turbocharger is inactive, and also capable of operating in a second mode, where both the primary turbo charger and the secondary turbo charger are active, the control system comprises: a detection device for verify the primary turbo charger to determine a current value for a turbocharger arrow speed primary; control logic for determining the presence or absence of a mode switching pending condition, wherein the sequential turbo charging system operates in the first mode and it is desired to operate the sequential turbo charging system in the second mode; control logic for determining a turbocharger arrow speed limit value based on the presence or absence of the mode switching pending condition; control logic to determine an error signal based on the current value for the primary turbo charger date speed and the turbocharger arrow speed limit value; control logic to determine a dynamic motor torque limit value based on the error signal, in order to track the current value for the primary turbocharger arrow speed to the turbocharger arrow speed limit value; and control logic to limit a motor torque applied to the dynamic motor torque limit value, wherein the turbocharger arrow speed limit value during the presence of a mode switching pending condition, significantly exceeds the turbocharger arrow speed limit during the absence of the mode switching pending condition, such that the presence of the mode switching pending condition results in a significantly increased error signal, resulting in a value significantly increased dynamic motor torque limit.
5. 5. The control system according to claim 4, characterized in that the turbocharger arrow speed limit value is based on engine speed.
6. 6. - The control system according to claim 4, characterized in that it further comprises: control logic to switch the system mode of sequential charge turbo from the first mode to the second mode, so that both the primary turbo charger and The secondary turbo charger are active.
7. 7. - A computer readable storage medium having stored information representing instructions that are executed by an engine controller, to control a vehicle having an internal combustion engine with a sequential turbo charge system, the sequential turbo charge system includes a primary turbocharger and a secondary turbocharger, and which is capable of operating in a first mode, where the primary turbocharger is active while the secondary turbocharger is inactive, and is also capable of operating in a second mode, in where both the primary turbo charger and the secondary turbocharger are active, the computer readable storage medium further comprises: instructions for determining the presence or absence of a condition pending mode switching, wherein the sequential turbo charging system operates in the first mode and it is desired to operate the sequential turbo charging system in the second mode; instructions for determining a turbocharger arrow speed limit value based on the presence or absence of the mode switching pending condition; instructions to verify the primary turbo charger, to determine a current value for a turbocharger arrow speed primary; instructions for determining an error signal based on the current value for the arrow speed of the primary turbocharger and the limit value of the arrow speed of the turbocharger; instructions for determining dynamic motor torque limit value based on the error signal in order to track the current value for the arrow speed of the primary turbo charger to the limit value of the turbocharger arrow speed; and instructions for limiting a motor torque applied to the limit value of dynamic motor torque, wherein the limit value of the arrow speed of the turbo charger during the presence of the mode switching pending condition, significantly exceeds the turbocharger arrow speed limit during the absence of the mode switching pending condition, such that the presence of the mode switching pending condition results in a significantly increased error signal, resulting in a limit value of torque of dynamic motor, significantly increased.
8. 8. - The computer-readable storage medium according to claim 7, characterized in that the instructions for determining the turbo charger arrow speed limit value further comprise: instructions for determining the turbocharger arrow speed limit value with based on the speed of the engine.
9. 9. - The computer readable storage medium according to claim 7, characterized in that it further comprises: instructions for switching the system mode of sequential charge turbo from the first mode to the second mode, so that both the primary turbo charger and the secondary turbo charger are active.