MXPA99010930A - Method and system for engine control - Google Patents

Abstract

A system and method for reducing cab vibration during engine shutdown in a vehicle (10), including an ICE (12), an engine brake (14), and an electronic control unit (20) for controlling the engine and the engine brake, includes logic for determining when a shutdown condition is occurring, and logic for generating a control signal to activate the engine brake during the engine shutdown. A plurality of sensors (16), including engine speed sensor (18) connected to the controller (20) via input ports (22). The controller includes a microprocessor (24) connected with memory (26) via bus (28). The activation of the engine brake is performed only after the engine speed has fallen below a predetermined level. The system and method also automatically deactivates the engine at a preselected time, such as when the engine speed falls below a second predetermined level, to ensure that the engine brake is not activated upon restarting the engine.

Description

METHOD AND SYSTEM FOR MOTOR CONTROL TECHNICAL FIELD The present invention relates to a method and system for reducing cabin vibration during engine shutdown. BACKGROUND OF THE INVENTION [0002] In the control of diesel or combustion internal combustion engines, conventional practice uses electric 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 a plethora of detectors, actuators, and sometimes other electronic control units needed to control various functions that may include fuel supply, cooling fan control, or excessive velocity and governed speed protection of the engine, engine braking, torque control, vehicle speed control or myriads of others. Such a method and apparatus for complete integrated motor control are described in U.S. Pat. No. 5,445,128, issued on August 29, 1995 to Letang et al., "Method For Engine Control" and granted to Detroit Diesel Corporation, assignee of the present invention. A type of engine method and system to obtain a braking effect in an internal fuel engine, involves converting the engine into an air compressor, that is to say when opening a valve to the atmosphere near the end of the compression stroke and closing it shortly after. The torque of the moving vehicle can be delayed using this system, which is commonly referred to as "Jake Braking". Such a conventional engine braking system is available from Jacobs Manufacturing Company, of Wilmington, Delaware. It is also known to use an electronic motor control to automatically stop and start an engine, in response to selected conditions that are verified by the engine control system, such as air temperature. PCT publication No. WO 95/31638, published November 23, 1995, discloses an engine control including these automatic engine start and stop capabilities. A problem encountered in the implementation of the automatic engine stopping characteristics is an annoying vibration of the cab. It is therefore convenient to provide a system and method for reducing cabin vibration during engine shutdown, which can be implemented automatically by electronic engine control units. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control system and method that can be implemented as part of a complete integrated electronic engine control unit to reduce cabin vibration during engine shutdown. To carry out the above objective and other objects and features of the present invention, a method and system are provided to reduce cabin vibration during engine shutdown in a vehicle, including an internal fuel engine and an electronic control unit for control the engine when activating the engine brake. The system includes an electronic control unit in communication with a motor RPM detector and a motor shutdown condition indicator, detector supply and / or motor control, and the logic that is executed to activate the motor brake. , when the engine shuts down. The preemptive system checks the engine RPM and activates the engine brake when the engine is in the auto-off condition, and the engine RPM has dropped below a predetermined engine brake-on threshold. The system also preferably deactivates the engine brake deactivation threshold to ensure that the engine brake is not activated when the engine is subsequently reset (either automatically or manually). The preference system automatically activates the engine brake only after determining that the fuel supply to the engine has been interrupted, in this way ensuring a smooth and efficient interruption. The foregoing objects and other objects, features and advantages of the present invention will be readily apparent to a person of ordinary skill in the art 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 is a block diagram of the engine interruption method of the present invention, implemented as part of an integrated complete engine control system. Figure 2 is a block diagram of the system of the present invention; and Figure 3 is a flow diagram of one embodiment of the method and system of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Referring now to Figure 1, a block diagram of the system and method of the present invention are illustrated. The system is particularly suitable for use in a vehicle 10 that includes a motor 12 that employs a motor braking system 14. A plurality of detectors 16 typically include motor speed detectors 18 in electrical communication with the controller 20 via gates of 22. The controller preferably includes a microprocessor 24 in communication with various computer readable storage means 26 via a control and data conduit 28. Computer readable storage means 26 may include any of a number of known devices that function as read only memory (ROM) 30, random access memory (RAM) 32, memory to keep active (KAM) 34 and the like. The computer readable storage media can be implemented by any of a number of known physical devices, capable of storing data representing executable instructions by a computer such as controller 20. Known devices may include but are not limited to PROMs, EPROMs, EEPROMs , flash memory and the like, in addition to magnetic optical means and combinations capable of temporary or permanent data storage. Computer-readable storage means 26 includes various program instructions, software (software) and control logic to effect control of various systems and sub-systems of the vehicle 10, such as the engine 12, transmission and the like. The controller 20 receives signals from the detectors 16 via feed gate 22 and generates output signals that can be provided to various actuators and / or components by output gates 36. Signals can also be provided to an display device 38 that include various indicators such as lamps 40 for communicating information regarding the operation of the system to the vehicle operator. The display 38 may also include an alpha-numeric portion or other convenient operator interface to provide status information to a vehicle operator or a technician. As such, the display 38 represents one or more displays or indicators that can be located through the interior and exterior of the vehicle, but preferably located in the cabin or interior of the vehicle. A manually operable control switch 42 can be employed by the vehicle operator to select the desired level of operation of the engine brake. In an engine braking system employed, available from Jacobs Manufacturing Company, of Wilmington, Delaware, two toggle switches are provided to allow selection of one of four engine braking levels corresponding to off, low, medium and high engine braking. . As with other conventional braking systems, braking the engine is achieved by increasing the pressure of the discharge stroke of at least one of the cylinders. An increased engine braking can be obtained by increasing the number of cylinders, progressively more engine power is dissipated. For example, in a six-cylinder diesel engine, it is provided under engine braking by increasing the pressure stroke of two cylinders while the average engine braking increases the discharge stroke portion of four cylinders. High engine braking increases the discharge stroke pressure of all six cylinders. In this way, the operator has the ability to select the degree of braking of the engine to be used by the system, to achieve an interruption or even stop of the engine. Alternatively, the operator can replace the operation of the present invention by switching the braking of the motor to standstill, in which case the automatic motor stop will not use the motor brake.

A data, diagnostics and programming interface 44 can also be selectively connected to the controller 20 via an outlet 46 for exchanging various information between them. The interface 44 can be used to change values within the computer readable storage medium 26, such as configuration settings, calibration variables, control logic and the like. As previously mentioned, the detectors 16 preferably include a motor speed detector 18. The motor speed can be detected using any of a number of known detectors that provide signals indicative of rotational speed for the flywheel, or various internal components of the motor such as the crankshaft, the camshaft or the like. In a preferred embodiment, the speed of the motor is determined using a synchronization reference signal generated by a multi-tooth wheel coupled to the camshaft. As will be appreciated by one of ordinary skill in the art, most vehicle applications will neither require nor utilize all of the detectors illustrated in Figure 1. As such, it will be appreciated that the objects, features and advantages of the present invention are independent of the particular way in which the operating parameters are detected. In operation, the controller 20 receives signals from the detectors and executes control logic embedded in physical equipment and / or software to verify the operation of the motor, to detect when an interruption of the motor has been initiated and to activate the engine brake. As desired, to assist in a uniform interruption. In a preferred embodiment, Controller 20 is the DDEC III controller available from the Detroit Diesel Corporation in Detroit, Michigan. Various other features of this controller will be 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. The control includes the ability to automatically stop and start the engine, such as the type described and illustrated in PCT publication No. WO 95/31638, which is hereby incorporated by reference in its entirety. Now with reference to Figures 2 and 3, a diagram and flowchart, respectively illustrating control logic representative of the system and method for the present invention are shown. Again, it will be appreciated that the control logic can be implemented or implemented in physical equipment, software (software) or a combination of physical equipment and software. The various preferred functions are performed by a programmed microprocessor such as the DDEC III controller, but may include one or more functions implemented by dedicated electrical, electronic and integrated circuits. As will be appreciated, the control logic can be implemented using any of a number of known programming or processing techniques or strategies and is not limited to the order or sequence illustrated here for convenience only. For example, event-driven processing or interruption, typically are used in real-time control applications, such as the control of a vehicle or transmission engine. Likewise, parallel processing or multi-task systems and methods may be employed to achieve the objects, features 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, the variables are typically initialized as indicated in 100, before configuring the controller. The variables that can be employed by the present invention include a first threshold at which the engine brake will be activated upon engine interruption, and a second threshold at which the engine brake will be deactivated before complete engine interruption. In a modality, these thresholds are in the motor speed (RM), and more preferably the first threshold is approximately 550 RPM and the second threshold is approximately 50 RPM. Again, it will be appreciated that other parameters may be employed to implement motor brake activation and deactivation, such as synchronization thresholds. For example, the first threshold * may be a selected amount of time after the engine interruption (or after fuel interruption during the engine interruption process), and the second threshold may be a specific amount of time. elapsed from the activation of the motor brake. Other variables can be used as long as they allow the control to effectively activate the motor brake during interruption to achieve a uniform interruption and preferably as long as they also allow for the engine brake to be deactivated in a timely manner so that the engine brake is not active when the engine is restarted. motor. The system at 102, then periodically verifies the existence of motor interruption condition. This may involve verifying the control system variable, a system interruption flag, or checking the power supply of the detector or other variables of the control system to determine if the supply of fuel to the engine has been interrupted. If the control system is automatically interrupting the motor, the system then generates the required control signal, at 104 to activate the motor brake, preferably at a first motor speed threshold of approximately 550 RPM. The system also preferably periodically checks the engine speed and at 106 generates a control signal to deactivate the engine brake at a second threshold, preferably at approximately 50 RPM, to achieve an engine breakdown aided by the engine brake uniform , while leaving the system in condition for uniform starting with the motor brake off. It will be appreciated that although it is contemplated that the system of the present invention will be implemented to operate the engine brake upon detecting an automatic system outage by the electronic motor controller. The system may additionally or alternatively be configured to activate the engine brake at any time the engine is interrupted, such as when the operator manually shuts off the engine. With reference to Figure 3, the preference system employs logic, to check at 110, to determine if the engine shutdown has been activated. For example, in the engine control system of the preferred embodiment, the controller will automatically shut off the engine under certain pre-selected conditions, such as that the cab reaches a selected temperature, or that a controlled temperature trailer reaches a selected temperature threshold. An indicator for activation of interruption, in the form of a software or variable banner will be sent under these conditions. This indicator is verified. If it is this indicator or other detected condition associated with the engine shutdown that is verified at 110. If the engine shutdown is activated, the system then preferably checks at 112, to determine if the engine control has interrupted the fuel supply to the engine. If so, the system then detects the current engine speed (RPM) at 114. If the engine speed has fallen below a preselected threshold, preferably approximately 550 RPM, the engine brake is activated at 116. This is it achieves by sending a convenient control signal to the motor control system as is well known in the art. Subsequently, the system then continues to check the engine speed at 118 and when the engine speed drops below a preselected motor brake deactivation threshold, preferably approximately 50 RPM, the system turns off the engine brake at 120, again when transmitting a convenient control signal. It will be appreciated that while the preferred embodiment described in Figure 3 uses selected variables and / or parameters detected, including an engine shut-off indicator, a fuel cut-off indicator and engine RPM information, the engine method and system. The present invention may use only some of these parameters or other parameters to implement braking of the engine during engine shutdown as illustrated by the present invention. For example, an alternate mode can activate the motor brake on a synchronized basis, after the occurrence of a monitored event, such as automatic engine shutdown or fuel shutdown. The system can also deactivate the engine brake after a selected period of time instead of based on the verified engine. Various other implementation methods will be appreciated by those skilled in the art to employ the engine brake to assist in the smooth shutdown of the engine in accordance with the present invention. Thus, 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 designs and alternate embodiments for practicing the invention as defined by the following claims.

Claims (12)

1. CLAIMS 1. A method for reducing cabin vibration during engine shutdown in a vehicle, including an internal combustion engine and an electronic control unit for controlling the engine, the method comprising activating the engine brake. In addition, it comprises determining the current engine speed and wherein the step of activating the engine brake is performed after the engine speed has fallen below a preselected value. The method according to claim 1, further comprising determining whether the supply of fuel to the engine has been interrupted, and wherein the step of activating the engine brake is carried out after the delivery engine has been interrupted. made out of fuel. The method according to claim 1, further comprising determining the current engine speed and where the engine brake is deactivated after the engine speed has fallen below a preselected value. 5. The method according to claim 2, characterized in that the preselected value is approximately 550 r.p.m. 6. The method according to claim 4, characterized in that the preselected value is approximately 50 r.p.m. 7. A system for reducing cabin vibration during engine shutdown in a vehicle, including an internal fuel engine, a compression release engine brake and an electronic control unit for controlling the engine and the engine brake, the system comprises control logic, to determine when a motor shutdown condition has occurred and, in the event of such occurrence, generate a control signal that activates the motor brake. The system according to claim 7, characterized in that the system also includes a motor speed detector to generate a signal indicative of the rotational speed of the motor, and where the control logic is in communication with the motor where the logic generates the control signal to activate the motor brake when the motor has reached a preselected first speed during shutdown. The system according to claim 7, characterized in that the control logic includes a power from the motor control, indicating whether the fuel has been interrupted to the motor, and where the control logic generates a control signal to activate the motor. the engine brake after the supply of fuel to the engine has been interrupted. 10. The system according to claim 8, characterized in that it also includes control logic for generating a signal that deactivates the motor brake after the motor has dropped below a preselected second speed. The system according to claim 8, characterized in that the first pre-selected speed is approximately 550 RPM. The system according to claim 10, characterized in that the second pre-selected speed is approximately 50 RPM.