Fixed temperature maintenance system for engine in unmanned aircraft having automatic throttle limiting device

Abstract

A system for maintaining a constant temperature of an engine in an unmanned aerial system with an autothrottle limiting device comprises an autopilot for issuing a throttle command, an autothrottle limiting device for automatically limiting an upper limit of the throttle command issued by the autopilot, and a rotary engine for feeding an internal temperature of the engine back to the autothrottle limiting device. The system is applicable to all kinds of unmanned aerial systems employing an air-cooling rotary engine, uses the existing autopilot of the unmanned aerial system without modification, and improves the reliability and life of the engine.

Claims

1. A system for maintaining a constant temperature of an engine in an unmanned aerial system, comprising: an autopilot for issuing a throttle command; and an autothrottle limiting device for automatically limiting an upper limit of the throttle command issued by the autopilot, based on an engine internal temperature fed back to the autothrottle limiting device from the engine; wherein the autothrottle limiting device comprises an autothrottle command value receiver for receiving an autothrottle command value from the autopilot; an autothrottle limited value subtraction unit for subtracting an autothrottle limited value from the autothrottle command value; an engine temperature receiver for continuously receiving the engine internal temperature of the engine; a limited operating temperature setting and switching unit for setting and switching a limited operating temperature for the engine internal temperature so as to operate the autothrottle limiting device; an engine maximum internal temperature limiter for limiting a maximum value of the engine internal temperature fed back to and received in the engine temperature receiver; and an autothrottle limited value calculator for calculating the autothrottle limited value by multiplying the engine internal temperature, of which the maximum value is limited, and a gain value.

2. The system according to claim 1, wherein, in a case where the limited operating temperature for the engine internal temperature is set to a predetermined value, the limited operating temperature setting and switching unit makes the autothrottle limiting device be automated if the engine internal temperature is higher than the predetermined value reduced by a predetermined amount, but makes the autothrottle limiting device use the autothrottle command value if the engine internal temperature is not higher than the predetermined value reduced by the predetermined amount.

3. The system according to claim 1, wherein the autothrottle limited value calculator multiplies the engine internal temperature, of which the maximum value is limited, and the gain value, the gain value being varied depending on altitudes.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a block diagram of a system for maintaining a constant temperature of an engine in an unmanned aerial system with an autothrottle limiting device according to an exemplary embodiment.

BEST MODE

(2) Below, embodiments of the present invention will be described in detail with reference to accompanying drawings. In the following description, terms or words used in the specification and claims are construed as not typical or lexical meaning but meaning and concept corresponding to the idea of the present invention on the principle that the inventor can properly define the concept of the terms in order to explain his/her own invention for the best.

(3) Therefore, it has to be understood that various equivalents and alternatives can be made at the time of filing the present invention since the descriptions of the specification and the features shown in the drawings are no other than preferred embodiments without reflecting all the technical ideas of the present invention.

(4) FIG. 1 is a block diagram of a system for maintaining a constant temperature of an engine in an unmanned aerial system with an autothrottle limiting device according to an exemplary embodiment.

(5) As shown in FIG. 1, a system for maintaining a constant temperature of an engine in an unmanned aerial system with an autothrottle limiting device includes an autopilot 100, an autothrottle limiting device 200 and a rotary engine 300.

(6) The autothrottle limiting device 200 includes an engine temperature receiver 210, an engine maximum internal-temperature limiter 230, a limited operating-temperature setting and switching unit 270, an autothrottle command-value receiver 280, and an autothrottle limited-value subtraction unit 290.

(7) The engine temperature receiver 210 continuously receives an internal temperature of the rotary engine 300, i.e. an engine internal temperature (or rotor air temperature (RAT).

(8) The autothrottle command-value receiver 280 receives an autothrottle command value from the autopilot 100.

(9) The autothrottle limited-value subtraction unit 290 subtracts an autothrottle limited-value from the autothrottle command value received in the autothrottle command-value receiver 280.

(10) The limited operating-temperature setting and switching unit 270 sets and switches a limited operating temperature for the internal temperature so that the autothrottle limiting device according to the present invention can operate.

(11) For example, in case where the limited operating temperature for the internal temperature is set to n as shown in FIG. 1, the limited operating-temperature setting and switching unit 270 makes the autothrottle limiting device be automated if the current internal temperature is higher than n10, but makes the autothrottle limiting device use the autothrottle command-value if the internal temperature is not higher than n10.

(12) By the way, the autothrottle limited-value for the autothrottle limited-value subtraction unit 290 is calculated by the following [Equation 1].
Throttle Limit=1/(RAT Limit(n)RAT)(10 or 20)[Equation 1]

(13) Referring to the Equation 1, the autothrottle limited-value subtraction unit 290 takes the reciprocal of a difference between the limited operating temperature set by the limited operating temperature setting and switching unit 270 and the current engine internal temperature.

(14) To prevent the engine internal temperature from being abnormally measured by failure in a thermometer, the engine maximum internal-temperature limiter 230 limits the maximum value of the engine internal temperature fed back to and received in the engine temperature receiver 210.

(15) In addition, an autothrottle limited-value calculator 250 calculates the autothrottle limited-value by multiplying the engine internal temperature, of which the maximum value is limited, and a gain value together.

(16) In particular, at an altitude higher than 2,000 m in the atmosphere, the engine internal temperature rises easily since air becomes thinner.

(17) Therefore, the autothrottle limited-value calculator 250 uses a low gain value 10 at an altitude equal to or lower than 2,000 m, but uses a high gain value 20 at an altitude higher than 2,000 m.

(18) For reference, if the engine internal temperature approximates to the limited operating temperature for the internal temperature, the autothrottle limited-value becomes higher to decrease the throttle, thereby having an effect on lowering the engine internal temperature.

(19) As described above, it is possible to decrease computer resources since the simple equation is used in automatically controlling the throttle, and the limited value makes it possible to stably operate the system for maintaining a constant temperature of an engine in an unmanned aerial system according to the present invention even in abnormal situations.

(20) Although a few exemplary embodiments have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

REFERENCE NUMERALS

(21) 100: autopilot 200: autothrottle limiting device 210: engine temperature receiver 230: engine maximum internal-temperature limiter 270: limited operating-temperature setting and switching unit 280: autothrottle command-value receiver 290: autothrottle limited-value subtraction unit 300: rotary engine