JPH06173708A - Air cooling type oil cooler - Google Patents

Abstract

PURPOSE:To enable an air cooling type oil cooler to be used by means of its simple structure without causing any overheat of oil temoerature, by making the radiating capacity of an air cooling fin smaller than that of an air cooling fin plate, and making the pressure loss in the first passage less than that in the second passage. CONSTITUTION:The first passage 20 provided in a cooler for cooling target oil and an air cooling fin 26 which is provided in an air passage effected by a fan 4 located in the vicinity of the first passage 20 are provided in an air cooling type oil cooler. An air cooling fin plate 6 positioned downstream from the air cooling fin 26 in the air passage effected by the fan 4 and the second passage 23 for cooling target oil which is provided in the air cooling fin plate 6 and connected downstream from the first passage 20 are provided in an air cooling type oil cooler. Futhermore, an oil passage 27 provided with a releaf valve 28 and bypassing the second passage 23 is provided. The heat radiating capacity of the air cooling fin 26 is smaller than that of the air cooling fin plate 6, and the pressure loss in the first passage 20 becomes less than that in the second passage 23. Especially, the air cooling type oil cooler is operated effectively during any cold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-cooled oil cooler with a gear driven fan used in a micro gas turbine engine for small unmanned aerial vehicles.

[0002]

2. Description of the Related Art Aircraft gas turbine engines are required to operate in a wide range of ambient temperatures from -40 ° C. or lower to + 50 ° C. or higher, and their rotational speeds are set high to achieve high performance. Therefore, the temperature of the oil rises significantly. Therefore, in large aircraft, the oil is usually cooled by a separate oil cooler.

However, in a small gas turbine engine mounted on a small unmanned aerial vehicle or the like, a space for mounting an oil cooler and a margin weight are small, and a power source for driving an oil cooling fan cannot be installed. The cooler is not provided separately, but is provided in the vicinity of the reduction gear box of the engine, and the oil cooling fan is driven by obtaining rotational force from the reduction gear.

FIG. 4 is a vertical sectional view of an oil cooler used in a micro gas turbine engine for a small unmanned aerial vehicle, and FIG. 5 is a view of the oil cooler seen from one end. In the figure, 1 is a housing of a reduction gear box of an engine,
2 is a fan driving gear that is rotated by a reduction gear in the housing, 3 is a rotating shaft that is connected to the gear, and the other end projects outside the housing 1. 4 is attached to the end of the rotating shaft. A fan is provided, an arrow 5 is a flow of air sent by the fan, and 6 is an air-cooling fin plate provided on the air outflow side of the fan, the inside of which serves as a cooling passage for oil. . 7 and 8
Are provided on the lower side and the upper side of the fin plate respectively, and a lower header and an upper header that communicate with an oil flow path inside the fin plate, 9 an oil inlet that communicates with the lower header 7, and 10 an upper header 8 It is an oil outlet leading to. Reference numeral 11 is a thermo-valve provided on the oil flow passage near the oil inlet 9, and 12 is a bypass flow passage extending from the thermo-valve to the oil outlet 10. Reference numeral 13 is a fin plate mounting bolt.

FIG. 6 is a system diagram of an oil circulation circuit in which this device is incorporated. In the figure, 100 is the above-mentioned oil cooler, 101 is an oil sump, 102 is an inflow pipe, one end of which is connected to the oil sump and allows oil to flow into the oil cooler, and 103 is an oil pump. The other end of the inflow pipe 102 is the oil inlet 9 of the oil cooler 100.
It is connected to. Outflow pipe 103 connected to the oil outlet 10
Goes through the filter 105 on the way to the oil sump 1
Constitutes an oil return path to 01. Note that 106
Is a system bypass connected to the inflow pipe 102, and 107 is a filter bypass that bypasses the filter 105 on the outflow pipe 104.

In the apparatus shown in FIG. 4, in principle, oil enters the air cooling fin plate 6 from the oil inlet 9 through the thermo valve 11 and the lower header 7. The oil is here cooled by the air 15 sent through the fan 4 outside the fin plate. After that, the oil flows out from the oil outlet 10 through the upper header 8. In this type of small oil cooler, the air-cooled fin plate 6 having a sufficient size cannot be provided. That is, the cross-sectional area of the oil flow path in the fin plate must be small. For this reason, in cold weather, if the cooling of the oil is continued, the temperature of the oil may drop, and the viscosity of the oil may become so large that the oil cannot flow.
Thus, the oil temperature is detected, and when it falls below a predetermined temperature, the oil that has entered from the oil inlet 9 is made to flow to the oil outlet 10 through the bypass flow passage 12.

[0007]

In the above prior art, the adoption of a complicated oil system using a thermovalve is not appropriate for weight saving and cost reduction when used in an unmanned aerial vehicle or the like.

If a relief valve having a simpler structure is used instead of the thermo valve, the temperature of the oil is lowered in cold weather, thereby increasing the viscosity and allowing the oil to flow through the bypass passage. Then, the oil becomes hot during circulation, but the oil inside the fin plate continues to be cooled by the outside air, so its viscosity does not recover to its original state, and the function of the cooler remains stopped after that. . Therefore, the oil temperature rises excessively, and it is not possible to reduce the weight and cost by simply replacing the thermovalve with a relief valve.

The present invention is intended to solve the above-mentioned drawbacks of the prior art and to provide an oil cooler which has a simple structure and which does not cause an excessive rise in oil temperature.

[0010]

SUMMARY OF THE INVENTION The present invention has been achieved to solve the above-mentioned problems, and in an air-cooled oil cooler with a gear drive type fan for a small gas turbine engine, a first oil to be cooled provided in the cooler is provided. A channel, an air-cooling fin provided near the first channel in the air channel by the fan, and an air-cooling fin plate located downstream of the air cooling fin in the air channel by the fan; A second flow path of oil to be cooled which is provided in the air-cooled fin plate and is connected to the downstream side of the first flow path; and a bypass flow path of oil which includes a relief valve and bypasses the second flow path. The air-cooled fin has a heat dissipation capacity smaller than that of the air-cooled fin plate, and the first flow passage has a lower pressure loss than the second flow passage. It relates to Ra.

[0011]

When the present apparatus is used at a temperature higher than the normal outside air temperature, oil flows through both the first flow path and the second flow path, and the oil is cooled in each. When this device is used in cold weather, the second part in the air-cooled fin plate with large heat dissipation capacity is used.
The oil in the flow channel has a low temperature, its viscosity increases, and it stops flowing in the second flow channel. At this time, the relief valve opens, and the oil flows out through the bypass passage without being cooled. This oil circulates in the circulation circuit and re-enters the first flow path. Since the pressure loss in this flow path is low, oil always flows. Since the heat radiation capacity of the air-cooled fins is relatively small, the oil circulates in the circulation circuit without being sufficiently cooled. Eventually, the temperature of the oil rises, and when the heated oil flows through the first flow path,
There, the heat of the oil is cooled to some extent, the heat of the oil is transferred to the air through the air-cooling fins, and flows through the outer surface of the air-cooling fin plate by the fan. As a result, the oil in the second flow passage provided therein is heated, its viscosity is reduced, and the oil flows in the second flow passage. The relief valve is closed, oil is allowed to flow through the second flow path, and air cooling is performed again there. In the present apparatus, the function of the second flow path is temporarily lost and the oil becomes high temperature in cold weather, but the high temperature is utilized to restore the function of the second flow path.

[0012]

1 is a vertical sectional view of an oil cooler according to an embodiment of the present invention, FIG. 2 is a view of the oil cooler seen from one end, and FIG. 3 is a system of an oil circulation circuit in which the above device is incorporated. It is a figure.

In FIG. 3, 200 is an oil cooler of this embodiment. In this circuit, the oil flowing through the inflow pipe 102 enters the cooler through the first flow path 20 and then exits through the intermediate pipe 29 connected to the same flow path to the cooler through the second flow path 23. And then flows out to the outflow pipe 104 and circulates. In other words, the oil is put into the oil cooler during one circulation.
Flow in times. The first flow path 20 is provided on the inflow side of air into the fan 4, and the second flow path 23 is provided on the outflow side of air from the fan 4. 21 is the oil inlet of the first channel, 2
Reference numeral 2 is an oil outlet of the first flow passage, 24 is an oil inlet of the second flow passage, and 25 is an oil outlet of the second flow passage. The oil pump 103 is provided on the intermediate pipe 29. A relief valve 27, which will be described later, is drawn in the figure. This system diagram is the same as the conventional system diagram (FIG. 6) except for the above.

In FIG. 1, 20 is the above-mentioned first flow path, which is provided in the gear box housing. This flow path has a structure with low pressure loss so that oil can flow even in cold weather. Reference numeral 21 is an oil inlet of the same first flow path, and 22 is an oil outlet of the same first flow path. 26 is a fan 4 near the first flow path 20 and outside the gearbox housing 1.
Is an air-cooled fin provided in the air inflow passage. The heat dissipation capacity of this air cooling fin is smaller than the heat dissipation capacity of the air cooling fin plate 6 described later. 23 is the above-mentioned second
A flow channel, which is provided in the air-cooled fin plate 6. That is, this portion has the same structure as the cooling channel in the prior art. The heat dissipation capacity of the fin plate 6 is larger than the heat dissipation capacity of the air cooling fin 26. Reference numeral 24 is an oil inlet of the second flow passage, and 25 is an oil outlet of the second flow passage.

In FIG. 2, reference numeral 27 is an oil bypass passage provided so as to directly connect the lower header 7 and the upper header 8, and 28 is a relief valve provided in the same passage. The parts other than the above are the same as those of the conventional technique (FIGS. 4 and 5).

When this apparatus is used at a temperature higher than the normal outside air temperature, oil flows through both the first flow path and the second flow path, and the oil is cooled in each.

When this apparatus is used in cold weather, the oil in the second flow passage 23 in the air-cooled fin plate having a large heat dissipation capacity becomes low temperature, its viscosity increases, and it stops flowing in the second flow passage.
At this time, the relief valve 28 is opened, and the oil flows from the lower header 7 to the upper header 8 via the bypass passage 27. That is, the oil flows out from the second passage oil outlet 25 without being cooled. This oil circulates in the circulation circuit of FIG. 3 and reenters the first flow path 20. Since the pressure loss in the flow path in this portion is low, oil always flows. Since the heat dissipation capacity of the air cooling fin 26 is relatively small, the oil circulates in the circuit (FIG. 3) without being sufficiently cooled. If this state continues,
Eventually the oil temperature rises. Oil heated is the first
When flowing through the flow path 20, the oil is cooled to some extent, the heat of the oil is transferred to the air through the air cooling fins 26, and flows through the outer surface of the air cooling fin plate 6 by the fan 4. As a result, the oil in the second flow path 23 provided therein is heated, its viscosity is lowered, and the oil flows in the second flow path 23. The relief valve 28 is closed, and most of the oil is allowed to flow through the second flow path 23, and air cooling is performed again there.

As described above, in the present embodiment, the function of the second flow path is temporarily lost during cold weather, and the oil becomes high in temperature, but the high temperature is used to restore the function of the second flow path. Therefore, it will function effectively in cold weather. Since a relief valve with a simple structure is used as the valve instead of a thermo valve, weight reduction and cost reduction can be realized.

[0019]

In the air-cooled oil cooler of the present invention, the first passage for the oil to be cooled provided in the cooler and the air passage by the fan are provided in the vicinity of the first passage. An air-cooling fin, an air-cooling fin plate located downstream of the air-cooling fin in the air flow path of the fan, and a second flow of cooling target oil provided in the air-cooling fin plate and connected to the downstream side of the first flow path. Road,
The air cooling fin has a heat radiation capacity smaller than that of the air cooling fin plate, and the first flow path is greater than the second flow path. Since the structure has a low pressure loss, it has a simple structure and can be used without causing an excessive rise in the oil temperature.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an oil cooler according to an embodiment of the present invention.

FIG. 2 is an end view of the oil cooler of the same embodiment.

FIG. 3 is a system diagram of an oil circulation circuit incorporating the oil cooler of the same embodiment.

FIG. 4 is a vertical sectional view of a conventional oil cooler.

FIG. 5 is an end view of the oil cooler.

FIG. 6 is a system diagram of an oil circulation circuit incorporating the oil cooler.

[Explanation of symbols]

 1 Gear Box Housing 2 Fan Drive Gear 3 Rotating Shaft 4 Fan 5 Air Flow 6 Air Cooling Fin Plate 7 Lower Header 8 Upper Header 9 Oil Inlet 10 Oil Outlet 11 Thermo Valve 12 Bypass Flow Path 13 Fin Plate Mounting Bolt 20 1st Flow path 21 Oil inlet of first flow path 22 Oil outlet of first flow path 23 Second flow path 24 Oil inlet of second flow path 25 Oil outlet of second flow path 26 Air cooling fin 27 Bypass flow path 28 Relief valve 29 Intermediate piping 100 oil cooler (conventional) 200 oil cooler (example)

Claims (1)

[Claims] 1. An air-cooled oil cooler with a gear-driven fan for a small gas turbine engine, wherein a first flow path of oil to be cooled provided in the cooler and air from the fan adjacent to the first flow path. An air cooling fin provided in the flow path, an air cooling fin plate located downstream of the air cooling fin in the air flow path by the fan, and provided in the air cooling fin plate and connected to the downstream side of the first flow path. The air-cooling fin has a heat dissipation capacity smaller than that of the air-cooling fin plate, and a second flow path for cooling oil, and a bypass flow path for oil that includes a relief valve and bypasses the second flow path. An air-cooled oil cooler characterized in that one passage has a structure with a lower pressure loss than the second passage.