JPH07232700A - Cooling device for internal combustion engine for air craft - Google Patents

Abstract

PURPOSE:To cause the automatic passage of a desired flow of cooling air matching with an engine output through a radiator. CONSTITUTION:A cooling device for an internal combustion engine for an aircraft comprises a cooling air passage 5 through which air is introduced from the outside of a machine body 1 to a radiator 4 and air after the passage of it through the radiator 4 is guided to the outside of the machine body 1; a cowl flap 6 disposed in the cooling air passage 5; a differential pressure detecting means 13 to detect an air differential pressure between a position situated right upper stream from the radiator 4 and a position situated right downstream therefrom; and an opening control means 10 to control the opening of the cowl flap 6 so that an air differential pressure detected by the differential pressure detecting means 13 is adjusted to a target value determined according to an engine output taking X atmospheric conditions during flying into consideration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for an aircraft internal combustion engine.

[0002]

2. Description of the Related Art A general aircraft internal combustion engine cooling device is provided in a cooling air passage for introducing air from the outside of the fuselage into a radiator and for introducing air after passing through the radiator to the outside of the fuselage. With a cowl flap, the operator manually adjusts the opening degree of the cowl flap to allow the radiator to pass a desired flow rate of cooling air according to the engine output so as to maintain the cooling water temperature within a predetermined range. It is what makes me. In recent years, automation of such cooling air flow rate control has been desired.

As a cooling device for an internal combustion engine for an automobile, Japanese Utility Model Laid-Open No. 61-43929 discloses a radiator in which the back surface of the radiator is covered with a shroud, and a fan is arranged in one of two openings formed in the shroud and the other. A shutter that can be opened and closed by a motor is arranged in the, and only when the running wind on the front of the radiator when the vehicle is running exceeds a predetermined flow velocity,
It is described that the fan is stopped and the shutter is automatically opened.

[0004]

In order to reduce the power consumption of the fan, this cooling device for an internal combustion engine for an automobile has a flow velocity of traveling wind detected by a flow velocity sensor provided in front of a radiator of a predetermined value or more. In such a case, it is determined that the cooling air passing through the radiator will exceed a predetermined flow rate, the fan is stopped and the shutter is opened, and this traveling wind is used for cooling the radiator. Therefore, even if this cooling air flow rate control is directly applied to the internal combustion engine for an aircraft, the above-mentioned cooling air flow rate control that has been manually performed in the past cannot be automated, and even if the internal combustion engine for an automobile is assumed to be used. Even when the cooling air flow rate control desired for the engine is carried out for the internal combustion engine for an aircraft, since the air pressure condition of the aircraft changes during the flight, even if the air velocity on the upstream side of the radiator exceeds the predetermined value, the air flow rate is higher than the predetermined flow rate. Cooling air will not pass through the radiator. Further, the air flow velocity on the front surface of the radiator varies greatly depending on its measurement position, and the flow velocity sensor cannot accurately control the cooling air flow rate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cooling device for an internal combustion engine for an aircraft which can automatically pass a desired amount of cooling air according to the engine output to a radiator.

[0006]

A cooling device for an aircraft internal combustion engine according to the present invention comprises a cooling air passage for introducing air from the outside of the machine into a radiator and a passage of air after passing through the radiator to the outside of the machine, and the cooling air passage. The cowl flap provided in the, the differential pressure detection means for detecting the air differential pressure on the upstream side and the downstream side of the radiator, and the air differential pressure detected by the differential pressure detection means determines the atmospheric conditions during flight. An opening degree control means for controlling the opening degree of the cowl flap so that the target value is determined in consideration of the engine output.

[0007]

The above-described cooling device for an internal combustion engine for an aircraft includes a cooling air passage that introduces air from the outside of the fuselage into the radiator and that introduces air that has passed through the radiator to the outside of the fuselage, and a cowl flap provided in the cooling air passage. The differential pressure detection means detects the air differential pressure on the upstream side and the downstream side of the radiator, and the opening control means determines the air differential pressure according to the engine output in consideration of atmospheric conditions during flight. The opening degree of the cowl flap is controlled so as to reach the determined target value.

[0008]

1 is a schematic sectional view showing a cooling system for an internal combustion engine for an aircraft according to the present invention. In the figure, 1 is an airframe, 2 is an internal combustion engine disposed inside the airframe 1, 3
Is a propeller arranged outside the machine body 1 and connected to the internal combustion engine 1. Reference numeral 4 denotes a radiator for cooling the cooling water of the internal combustion engine 2, which is provided in a cooling air passage 5 that connects an air inlet 5a provided on the front surface of the machine body 1 and an air outlet 5b provided on the lower surface of the machine body 1. It is arranged. The air inlet 5a is provided at a position where the air sent to the rear by the propeller 3 flows in so that the radiator 4 can be cooled even during flight.

The air outlet 5b of the cooling air passage 5 is provided with a cowl flap 6 which is driven by a step motor 6a or the like and whose opening can be adjusted. A cooling fan 7a is provided downstream of the radiator 4 in the cooling air passage 5, and a heating passage 7 is connected to heat the cabin by using the warmed air that has passed through the radiator 4.
The heating passage 7 is formed downstream of the blower 7a so as to guide the above-mentioned air around the cabin.
And a second passage 7c that communicates with the outside of the machine body 1, and a switching valve 7d that allows communication between the blower 7a and one of the first and second passages 7b and 7c is arranged at this branching portion. ing.

Reference numeral 10 is a control device for controlling the opening degree of the cowl flap 6, which includes an outside air temperature sensor 11 for detecting the outside air temperature, an outside air pressure sensor 12 for detecting the outside air pressure, and a radiator 4 for the cooling air passage 5. Each sensor such as a differential pressure sensor 13 that detects an air differential pressure between immediately upstream and downstream is connected.

The cooling device for an internal combustion engine for an aircraft thus configured controls the opening degree of the cowl flap 6 according to the flow chart shown in FIG. This flowchart is executed every predetermined time. First, step 101
3, the required cooling air flow rate Q for the current engine output is determined from the first map shown in FIG. 3 in consideration of the outside air temperature t detected by the outside air temperature sensor 11. The required cooling air flow rate Q is a flow rate of the cooling air that passes through the radiator 4 in order to exert a desired cooling effect, and in the first map, the higher the engine output, the larger the heat radiation amount, and the required cooling air amount correspondingly. The flow rate Q is set to be large, and if the outside air temperature t is low, the desired cooling air flow rate Q can be cooled even if the required cooling air flow rate Q is small. It is set for each temperature t.

Next, at step 102, the required cooling air flow rate Q is divided by the air density ρ based on the external pressure p detected by the external pressure sensor 12, the required cooling air flow velocity V is calculated, and the routine proceeds to step 103, From the second map shown in FIG. 4, the target air differential pressure ΔP immediately upstream and downstream of the radiator 4 in the cooling air passage 5 for realizing the required cooling air flow velocity V is determined. The second map is a logarithmic required cooling air velocity V and a logarithmic target air differential pressure Δ.
The relationship with P is shown.

Next, at step 104, a difference D between this target air differential pressure ΔP and the actual air differential pressure ΔP 'detected by the differential pressure sensor 13 is calculated, and at step 105, this difference D is positive. Cowl flap 6 in some cases
Is gradually increased from the present, and when the difference D is negative, the opening of the cowl flap 6 is gradually reduced from the present so that a new target air differential pressure ΔP is set in the next process. Until it is determined, feedback control is performed so that this difference D is close to zero.

As described above, the opening degree of the cowl flap 6 is controlled so that the actual air differential pressure ΔP 'between the cooling air passage 5 immediately upstream and downstream of the radiator 4 becomes the target air differential pressure ΔP. Therefore, only the currently required cooling air flow rate in consideration of the engine heat radiation amount and the outside air temperature t can be automatically passed through the radiator 4, and the cooling water temperature rises abnormally to overheat the internal combustion engine. It is prevented from abnormally descending and freezing, and it is always maintained within a predetermined range, and good internal combustion engine cooling can be realized.

To heat the cabin, a blower 7a is used.
And the first passage 7b are communicated with each other, the switching valve 7d is switched, the load is controlled so that the desired cabin temperature is realized, the blower 7a is driven, and the warmed air after passing through the radiator 4 is discharged. Supplied around the cabin.

When the blower 7a is driven, the air pressure immediately downstream of the radiator 4 is forcibly reduced, so that the target air differential pressure ΔP at this time cannot be achieved even when the cowl flap 6 is fully opened because the flight speed is slow. At times, the blower 7a may be driven appropriately. At this time, if heating of the cabin is unnecessary, the switching valve 7d is switched so that the blower 7a and the second passage 7c are communicated with each other, and the warmed air after passing through the radiator 4 is discharged to the outside of the body 1.

The above-mentioned cooling air flow rate control can make this control reliable because it uses a differential pressure that can provide a stable output, unlike a flow velocity that greatly varies depending on the measurement position, and is more than necessary. Since the cooling air of 1 is not taken into the airframe 1, the flight resistance can be minimized.

In the present embodiment, the feedback control in which the opening degree of the cowl flap 6 is gradually increased and decreased is performed in step 104 of the above-mentioned flow chart, but in order to simplify this control, the target air differential pressure ΔP and the air pressure The increase / decrease opening from the current opening may be determined according to the magnitude of the difference D from the differential pressure ΔP ′.

[0019]

As described above, according to the cooling system for an aircraft internal combustion engine of the present invention, a cooling air passage for introducing air into the radiator from the outside of the machine body and for introducing air after passing through the radiator to the outside of the machine body, and cooling air. And a cowl flap provided in the passage, the differential pressure detection means detects the air differential pressure on the upstream side and the downstream side of the radiator, and the opening degree control means determines the atmospheric conditions during flight by this opening differential pressure means. In order to control the opening of the cowl flaps so that it becomes a target value that is determined according to the engine output in consideration of the desired flow rate according to the engine output that changes depending on the outside air temperature during the flight when the atmospheric conditions change. Cooling air can be accurately supplied to the radiator based on the outside air pressure, and it becomes possible to automatically maintain the engine cooling water temperature within a predetermined range, overheating of the internal combustion engine and freezing of cooling water. It is possible to achieve good cooling of the internal combustion engine but is prevented.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a cooling device for an aircraft internal combustion engine according to the present invention.

FIG. 2 is a flowchart for controlling the opening degree of a cowl flap.

FIG. 3 is a first map used in the flowchart of FIG.

FIG. 4 is a second map used in the flowchart of FIG.

[Explanation of symbols]

 1 ... Airframe 2 ... Internal combustion engine 4 ... Radiator 5 ... Cooling air passage 6 ... Cowl flap

Claims (1)

[Claims] 1. A cooling air passage for introducing air into the radiator from the outside of the machine body and for introducing air after passing through the radiator to the outside of the machine body, a cowl flap provided in the cooling air passage, and an upstream side of the radiator. The differential pressure detecting means for detecting the air differential pressure on the immediate downstream side, and the air differential pressure detected by the differential pressure detecting means become a target value determined according to the engine output in consideration of atmospheric conditions during flight. An opening control means for controlling the opening of the cowl flap as described above, and a cooling device for an aircraft internal combustion engine.