Fluid reaction surfaces (i.e. – impellers) – Method of operation
Reexamination Certificate
2000-08-31
2002-10-22
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Method of operation
C416S037000, C416S043000, C123S436000
Reexamination Certificate
active
06468035
ABSTRACT:
TECHNICAL FIELD TO WHICH THE INVENTION BELONGS
The present invention relates to a method and apparatus for controlling an airplane engine and, more particularly, to a method which enables easier control of a reciprocating engine of an airplane and which sets the engine in such an operating condition in a partial power mode as to maximize the efficiency of the airframe and the engine as a whole, and to an apparatus for controlling an airplane engine according to the method.
PRIOR ART
Conventionally, to control drive of a reciprocating engine of a small plane having a variable-pitch propeller, a drive control system is used in which the engine torque is controlled by means of a throttle and a fuel regulator, and in which the number of revolutions of the propeller is controlled by means of a governor.
That is, the throttle sets the amount of air drawn into the engine, the fuel regulator sets the air-fuel ratio, and the governor controls the load on the engine by changing the propeller pitch, thus controlling the engine so that the engine has a set number of revolutions.
This engine drive control is performed by operating the throttle with a throttle lever, operating the fuel regulator with a mixture lever, and operating the governor with a governor lever. A pilot of the airplane sets the number of revolutions of the propeller governor to a desired number by operating the governor lever, adjusts the throttle opening by operating the throttle lever, and controlling the air-fuel ratio setting in the engine by. operating the mixture lever, thereby obtaining the desired engine output.
In the above-described conventional engine drive operating system for a small plane having a variable-pitch propeller, it is necessary for a pilot to perform troublesome steps of operating the three operating levers in order to obtain the desired engine output.
The publication of U.S. Pat. No. 4,626,170 discloses a normal aspiration engine for an airplane with a variable-pitch propeller, which is designed so that the throttle opening and the set number of governor revolutions can be simultaneously controlled with one lever.
In the engine disclosed in this patent publication, a fuel injection controller is provided to control the amount of fuel injected into the engine according to the amount of air drawn into the engine, and the governor and the throttle valve are connected to one power control lever by a link mechanism. In this engine, the set number of revolutions of the propeller governor and the throttle opening are simultaneously changed according to the amount of operation of the power control lever. When the set number of revolutions of the propeller governor is small, the throttle opening is set to a small value. When the set number of revolutions of the propeller governor is large, the throttle opening is set to a large value.
PROBLEM TO BE SOLVED BY THE INVENTION
In general, when an airplane makes a short-distance flight, it flies with full engine power. In contrast, in the course of a long-distance flight, the airplane starts cruising when it reaches a predetermined altitude. During cruising, the airplane flies at 70 to 80% of the maximum engine power. Such power smaller than the maximum power is called partial power. Basically, the fuel efficiency of the engine is improved when such partial power is set.
To consider fuel economy of an airplane, the operating work efficiency of the airframe and the engine of the airplane as a whole, i.e., the flight distance traveled by the airplane consuming a predetermined amount of fuel, including the efficiency of the propeller connected to the engine, i.e., the efficiency at which the engine output is converted into a thrust by the propeller, must be taken into consideration as well as the fuel efficiency of the mounted engine itself.
In the case of the invention described in the specification of U.S. Pat. No. 4,626,170, full opening of the throttle is presupposed with respect to the range of 2000 or more engine revolutions per minute, as shown in FIG.
25
. When the throttle is fully open, there is no suction loss in the engine, so that the fuel efficiency of the engine is high.
However, from representation of the relationship between the throttle and the number of engine revolutions and the relationship between the torque and the number of engine revolutions reflecting the former relationship as shown in
FIG. 26
, it can be understood that a large discrepancy can be seen between an arbitrary point F designating a number of revolutions of 2000 or more and a point G designating the same number of revolutions as the point F on a maximum propeller efficiency line L (on which a relationship expressed by Te ∝ &rgr;N
2
is established between the torque Te and the number of engine revolutions Ne) supposed from the relationship between the torque and the number of engine revolutions.
Therefore, it is possible to say that the invention of the above-mentioned U.S. patent is incomplete in terms of fuel economy conditioned by the efficiency of the airframe and the engine of an airplane as a whole including the propeller efficiency.
In view of the above-described circumstances, an object of the present invention is to provide an airplane engine control method and apparatus which can realize an optimal propeller efficiency when partial power is set in an engine of an airplane, and which can set a good operating condition by improving fuel efficiency of the airframe and the engine of the airplane as a whole.
Another object of the present invention is to provide an airplane engine control method and apparatus which can maintain a propeller-efficiency-maximized condition when partial power is set in a normal aspiration engine of an airplane and thereby realize a good operating condition of the airframe and the engine of the airplane as a whole including fuel efficiency of the engine.
Still another object of the present invention is to provide an airplane engine control method and apparatus which can maintain a propeller-efficiency-maximized condition when partial power is set in an engine with a turbocharger of an airplane and thereby realize a good operating condition of the airframe and the engine of the airplane as a whole including fuel efficiency of the engine.
Yet still another object of the present invention is to provide an airplane engine control method and apparatus which can maintain a propeller-efficiency-maximized condition in accordance with a change in the drag of airplane even when the drag of airplane is changed by, for example, a change in weight during a flight and thereby realize a good operating condition of the airframe and the engine of the airplane as a whole including fuel efficiency of the engine.
Yet still another object of the present invention is to provide an airplane engine control method and apparatus which can improve the controllability of an engine of an airplane to be controlled by a pilot while a propeller-efficiency-maximized condition is maintained to realize a good operating condition of the airframe and the engine of the airplane as a whole including fuel efficiency of the engine.
MEANS FOR SOLVING THE PROBLEM
According to the present invention, there is provided a method of controlling a reciprocating engine with a variable-pitch propeller provided on an airplane, in which suitable partial power is set in the engine, the method comprising setting an engine condition such that a relationship represented by Te ∝ &rgr;N
2
is established with respect to the engine torque (Te), the number of engine revolutions (N) and the atmospheric density (&rgr;) when predetermined partial power is set in the engine.
1. Explanation of Principle
The inventors of the present invention have achieved the present invention with the aim of improving, as well as the engine fuel efficiency, the fuel efficiency of an airplane conditioned by the efficiency of the airframe and the engine of the airplane as a whole including the propeller efficiency when partial power is set in the engine, and also improving the controllability of the engine to b
Otake Yukio
Tanaka Shinichiro
Look Edward K.
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
White Dwayne J.
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