Electronic engine synchronizer

Details Electronic engine synchronizer Electronic engine synchronizer

2001-09-17

2004-02-24

Nguyen, Hoang (Department: 3748)

Power plants

System having plural motors or having diverse types of...

Having condition responsive control

C060S706000, C060S711000

Reexamination Certificate

active

06694741

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to control area networks (CANs) for managing the operation of internal combustion engines, and more specifically to systems for synchronously controlling a plurality of such engines. The invention is disclosed in the context of a multiple trailer road train vehicle, but is believed to be useful in other applications as well.
BACKGROUND OF THE INVENTION
In some internal combustion engine applications, the required power output to drive a load exceeds the capability of a single engine and drive train combination. Some examples of such applications are generator sets, boats having twin propulsion screws, multi-engine aircraft, and multiple trailer road train vehicles. For these and other applications, engine synchronization systems are known in the art. For example, a mechanical device for synchronizing marine engines is described in the Herbert U.S. Pat. No. 3,258,927 granted Jul. 5, 1966, herein incorporated by reference. In the Sturdy U.S. Pat. No. 4,964,276 granted Oct. 23, 1990, herein incorporated by reference, an electronic synchronizer is described for controlling the speed of a second engine to maintain it in synchronism with a master speed signal from a first engine. In the Bernardi U.S. Pat. No. 5,771,860 granted Jun. 30,1998, herein incorporated by reference, another electronic synchronizer is described for controlling the power output from a second engine as a function of three variables. The three variables are the inlet manifold pressure of a first engine, the inlet manifold pressure of the second engine, and a signal produced by an offset potentiometer that compensates for minor differences between the manifold-pressure-to-power-output ratios of the two engines.
Most prior art systems designed to synchronize a plurality of engines involve monitoring the speed of a master engine and adjusting the speed of one or more slave engines to match the speed of the master engine. For engines driving a common load, control based on engine speed only functions properly if the engines and drive trains are identical. That is, at any engine speed, the torque output by each engine to the driven member (wheels, drive shaft, screw, etc.) must be the same. While these engine speed-based control methods are adequate for controlling identical engines, they do not provide a user with the ability to control engines having differing power and torque characteristics and drive-train configurations.
One method of synchronizing engines which does not use engine speed as the controlling parameter is shown in Bernardi. In the Bernardi patent, a system is disclosed for synchronizing the power output of two mechanically-linked engines, where the first engine transmits mechanical power through a shaft to the second engine, and the second engine transmits mechanical power to a load, such as an electrical generator. However, as summarized above, the disclosed method adjusts the throttle of a second engine as a function of the inlet manifold pressures of the two engines; the controller attempts to maintain equal manifold pressures in the two engines. This system assumes manifold pressure is a proxy for power output and engine speed. This assumption is only valid if the engines are identical, or near enough to identical that the disclosed offset potentiometer may compensate for the difference.
While these and other prior art systems generally perform adequately for the applications for which they are designed, they do not provide a means for controlling engines having differing power output and torque output characteristics, so that the engines may be adapted to drive a common load.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a control system is provided for use with at least a first engine producing a first torque and second engine producing a second torque. The control system comprises an interface between a first control computer associated with the first engine and a second control computer associated with the second engine. The first control computer is configured to control the second control computer through the interface such that the second torque is a function of the first torque.
Illustratively according to this aspect of the invention, the first engine has a first maximum torque output associated therewith. The interface receives a first percent torque message indicating a first percentage that equals the first torque divided by the first maximum torque. The interface generates a torque request message indicating a requested torque value indicating a requested torque to be produced by the second engine that is a function of the first percentage, and transmits the torque request message to the second control computer.
Further illustratively according to this aspect of the invention, the second engine has a second maximum torque output associated therewith. The interface receives a second percent torque message indicating a second percentage that equals the second torque divided by the second maximum torque output. The requested torque value is further a function of the second percentage.
Alternatively illustratively according to this aspect of the invention, the interface receives a first message indicating a first value from the first control computer and a second message indicating a second value from the second control computer. The interface calculates an error value indicating the difference between the first and second values. The interface utilizes this error value to calculate a requested torque value indicating a requested torque to be produced by the second engine to cause the error value to approach zero.
Further illustratively according to this aspect of the invention, the interface transmits a torque request message indicating the requested torque value to the second control computer.
Additionally illustratively according to this aspect of the invention, the interface provides a torque request signal indicating the requested torque value to the second control computer.
Additionally illustratively according to this aspect of the invention, the first value indicates a percentage that equals the first torque divided by the first maximum torque output.
Additionally illustratively according to this aspect of the invention, the first value indicates a brake mean effective pressure produced by the first engine.
Alternatively illustratively according to this aspect of the invention, the first control computer is coupled to a first network. The second control computer is coupled to a second network. The interface is coupled between the first and second networks.
According to another aspect of the invention a control system is provided for synchronizing the operation of a plurality of internal combustion engines. The system comprises, a first control computer associated with a first internal combustion engine, the control computer producing a first datum. The system further comprises a second control computer associated with a second internal combustion engine. The system further comprises an interface operatively coupled between the first and second control computers. The interface is responsive to the first datum to provide an operational command to the second control computer. The second control computer is responsive to the operational command to control the second engine, so that a first relationship exists between a second torque produced by the second engine and a first torque produced by the first engine.
Additionally illustratively according to this aspect of the invention, the first internal combustion engine has a first maximum torque output associated therewith. The first datum indicates a first percentage that equals the first torque divided by the first maximum torque output.
Further illustratively according to this aspect of the invention, the second internal combustion engine has a second maximum torque output associated therewith. The second control computer produces a second datum indicating a second percentage that equals the second torque divided by the second maximum torque output. The i

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