Patent Description:
A gas turbine engine used as a power source of an aircraft or the like includes a cylindrical case (external case) accommodating a compressor, a combustor, and a turbine, and various accessories are attached around the external case (see <CIT>, for example).

<CIT> discloses a gas turbine engine comprising a gas generator that includes a high pressure compressor, a combustor assembly, and a high pressure turbine in an axial serial flow relationship on a core engine rotor rotating about a core engine shaft. The gas turbine engine also includes a low pressure compressor or fan and a low pressure turbine. A thermal management system includes at least one fluid reservoir, including an oil tank containing lubricating oil arranged at the outlet guide vanes. <CIT> discloses a gas turbine engine including an annular fan casing and a plurality of outlet guide vanes which are connected to and disposed within the fan casing. A storage tank of a heat exchanger is arranged at the outlet guide vanes.

For example, it is desirable that to suppress air resistance when an aircraft gas turbine engine is mounted on an airframe, a frontal projected area of the gas turbine engine be made as small as possible, and the entire gas turbine engine including the accessories be reduced in diameter. However, according to current aircraft gas turbine engines, the accessories disposed on an outer peripheral surface of a casing are large. Therefore, the accessories largely project outward in a radial direction of the gas turbine engine, and this increases the frontal projected area of the gas turbine engine.

An object of the present invention is to provide a gas turbine engine that can be reduced in diameter.

This object is solved by a gas turbine engine having the features of claim <NUM>. A gas turbine engine according to one aspect of the present invention includes: an oil tank storing lubricating oil; and a cylindrical external case accommodating a compressor, a combustor, and a turbine. The oil tank is arranged along an outer peripheral surface of the external case so as to surround the external case.

According to this configuration, the oil tank can be prevented from largely projecting outward in a radial direction. Therefore, a frontal projected area of the gas turbine engine can be reduced, and the gas turbine engine can be reduced in diameter.

The present invention can provide a gas turbine engine that can be reduced in diameter.

Hereinafter, a gas turbine engine (hereinafter simply referred to as an "engine") <NUM> according to an embodiment will be described. The engine <NUM> of the present embodiment is a two-shaft turbo fan engine for an aircraft. However, the type and use of the engine <NUM> are not especially limited. <FIG> is a schematic diagram of the engine <NUM>. Hereinafter, a paper surface left side in <FIG> is referred to as a "front side," and a paper surface right side in <FIG> is referred to as a "rear side.

As shown in <FIG>, the engine <NUM> according to the present embodiment includes a fan <NUM>, a compressor <NUM>, a combustor <NUM>, a turbine <NUM>, an external case <NUM>, a lubricator <NUM>, and an oil tank <NUM>. Hereinafter, these components will be described in order.

The fan <NUM> includes fan blades <NUM>. The fan <NUM> rotates to take in air and supplies the air to the compressor <NUM> and a bypass passage <NUM> located outside the compressor <NUM> in a radial direction. If the fan blade <NUM> breaks, part of the fan blade <NUM> may go through the external case <NUM> and scatter to an outside of the engine <NUM>. Therefore, the engine <NUM> needs to be subjected to an antiscattering measure (containment measure) of the fan blades <NUM>. The antiscattering measure of the fan blades <NUM> will be described later.

The compressor <NUM> is a component that compresses the air flowing therein from the fan <NUM>. The compressor <NUM> may be: an axial compressor that compresses air which has been taken in from the front side, and supplies the air to the rear side, and supplies the air to the rear side; a centrifugal compressor that compresses air which has been taken in from the front side, and supplies the air outward in the radial direction; or a combination thereof. The air compressed by the compressor <NUM> is supplied to the combustor <NUM> located downstream of the compressor <NUM>.

The combustor <NUM> is a component that sprays a fuel to the air compressed by the compressor <NUM> and combusts them. The fuel used in the engine <NUM> is not especially limited, and the type of the combustor <NUM> is not especially limited. In the combustor <NUM>, a high-temperature and high-pressure combustion gas is generated by combusting the fuel. The combustion gas is supplied to the turbine <NUM> located downstream of the combustor <NUM>.

The turbine <NUM> is a component that is rotated by energy of the combustion gas generated by the combustor <NUM>. The turbine <NUM> may be: an axial turbine into which the combustion gas flows from the front side and through which the combustion gas flows to the rear side; a centrifugal turbine into which the combustion gas flows from the front side and through which the combustion gas flows outward in the radial direction; or a combination thereof. The turbine <NUM> of the present embodiment includes a high-pressure turbine <NUM> and a low-pressure turbine <NUM>.

The high-pressure turbine <NUM> is coupled to the compressor <NUM> through an external shaft <NUM>. Therefore, when the high-pressure turbine <NUM> is rotated by the combustion gas, this rotates the compressor <NUM>. The external shaft <NUM> is supported by a first bearing <NUM> and a second bearing <NUM> so as to be rotatable.

The low-pressure turbine <NUM> is coupled to the fan <NUM> through an internal shaft <NUM>. Therefore, when the low-pressure turbine <NUM> is rotated by the combustion gas, this rotates the fan <NUM>. The internal shaft <NUM> penetrates an inside of the external shaft <NUM> and rotates independently from the external shaft <NUM>. The internal shaft <NUM> is supported by a third bearing <NUM> and a fourth bearing <NUM> so as to be rotatable.

The external case <NUM> is a cylindrical case accommodating the fan <NUM>, the compressor <NUM>, the combustor <NUM>, and the turbine <NUM>. A cylindrical internal case <NUM> is disposed inside the external case <NUM> and has a center axis that coincides with a center axis of the external case <NUM>. Among the fan <NUM>, the compressor <NUM>, the combustor <NUM>, and the turbine <NUM>, the internal case <NUM> accommodates the components other than the fan <NUM>. The annular bypass passage <NUM> through which the air taken in by the fan <NUM> flows is formed between the external case <NUM> and the internal case <NUM>.

The lubricator <NUM> is a device that supplies lubricating oil to lubrication targets. The lubricator <NUM> of the present embodiment is a non-circulation lubricator and ejects air oil or oil mist, prepared by mixing the compressed air extracted from the compressor <NUM> and the lubricating oil, to the first bearing <NUM>, the second bearing <NUM>, the third bearing <NUM>, and the fourth bearing <NUM> that are the lubrication targets. However, the lubricator <NUM> may be a circulation lubricator that collects and reuses the used lubricating oil.

The oil tank <NUM> is a component that stores the lubricating oil. The oil tank <NUM> is disposed on an outer peripheral surface of the external case <NUM> and is arranged at an axial position corresponding to the fan <NUM>. To be specific, the axial position of the oil tank <NUM> overlaps the axial position of the fan <NUM>. In the present embodiment, an entire axial range of the fan <NUM> (i.e., a range from a front end to a rear end in the axial direction) is contained within an axial range of the oil tank <NUM>. However, part of the axial range of the fan <NUM> may overlap the axial range of the oil tank <NUM>.

As above, the oil tank <NUM> of the present embodiment is arranged at the axial position corresponding to the fan <NUM>. Therefore, when the fan blade <NUM> breaks, the oil tank <NUM> can block the scattering fan blade <NUM>. To be specific, in the engine <NUM> according to the present embodiment, the oil tank <NUM> is arranged at the axial position corresponding to the fan <NUM> in order to prevent the fan blades <NUM> from flying to an outside of the external case <NUM>. As a result, a containment ring that is generally used for antiscattering of the fan blades <NUM> can be omitted. Therefore, the engine <NUM> can be reduced in weight while securing a containment property.

<FIG> is a schematic front view of the engine <NUM>. As shown in <FIG>, the oil tank <NUM> is arranged along the outer peripheral surface of the external case <NUM> so as to surround the external case <NUM>. Since the oil tank <NUM> is arranged as above, the oil tank <NUM> can be prevented from largely projecting outward in the radial direction when viewed from a front side of the engine <NUM> (when viewed in the axial direction). As a result, the engine <NUM> can be reduced in diameter. The above effect can be obtained if the oil tank <NUM> is arranged in a region that has an angle of, for example, <NUM> degrees or more in a circumferential direction of the external case <NUM>.

In the present embodiment, the oil tank <NUM> is arranged in an annular shape over an entire circumference of the external case <NUM> in the circumferential direction. Since the oil tank <NUM> is arranged as above, the fan blades <NUM> can be surely prevented from scattering. In the present embodiment, the oil tank <NUM> is formed integrally. However, the oil tank <NUM> may be formed by coupling circular-arc tanks in the circumferential direction.

A radial thickness X of the oil tank <NUM> when viewed in the axial direction is constant in the circumferential direction. To be specific, when viewed in the axial direction, the radial thickness X of the oil tank <NUM> is constant regardless of circumferential positions. As above, since the radial thickness X of the oil tank <NUM> when viewed in the axial direction is constant in the circumferential direction, the oil tank <NUM> does not largely project in the radial direction, and therefore, the engine <NUM> can be further reduced in diameter.

Moreover, in the present embodiment, an outer diameter Y of the oil tank <NUM> is smaller than a largest outer diameter Z of the external case <NUM>. To be specific, when viewed in the axial direction, the entire oil tank <NUM> is contained within a range (hereinafter referred to as a "projected range") defined by an outer edge of the external case <NUM>. Moreover, in the present embodiment, when viewed in the axial direction, the lubricator <NUM> is also contained within the projected range of the external case <NUM>. When viewed in the axial direction, both of the oil tank <NUM> and the lubricator <NUM> do not have to be contained within the projected range of the external case <NUM>. If one or both of the oil tank <NUM> and the lubricator <NUM> are contained within the projected range of the external case <NUM>, the engine <NUM> can be further reduced in diameter. When the external case <NUM> includes a flange and the like, the projected range is a range defined by the outer edge of the entire external case <NUM> including the flange and the like.

The oil tank <NUM> is a sealed expansion tank including a liquid chamber <NUM> and an air chamber <NUM>. The lubricating oil is sealed in the liquid chamber <NUM>, and the liquid chamber <NUM> is expandable and contractable. The air chamber <NUM> is adjacent to the liquid chamber <NUM>. More specifically, the oil tank <NUM> is a bladder tank in which the liquid chamber <NUM> is made of rubber and has a bag shape. However, the oil tank <NUM> may be a diaphragm tank including an inside that is divided by a diaphragm into the liquid chamber <NUM> and the air chamber <NUM>.

In the present embodiment, the compressed air extracted from the compressor <NUM> is supplied to the air chamber <NUM> of the oil tank <NUM>. With this, the pressure in the air chamber <NUM> increases, and the volume of the liquid chamber <NUM> decreases. Thus, the lubricating oil in the liquid chamber <NUM> is discharged. A discharge port of the oil tank <NUM> may be located at any circumferential position. Moreover, the oil tank <NUM> may include one discharge port or may include plural discharge ports.

For example, if the oil tank <NUM> is a simple container, includes the discharge port in the vicinity of a bottom surface thereof, and is turned upside down since the posture of the engine <NUM> significantly changes, the lubricating oil cannot be discharged from the oil tank <NUM>. However, according to the present embodiment, since the oil tank <NUM> is the sealed expansion tank, the lubricating oil can be discharged regardless of the posture of the engine <NUM>.

Moreover, the liquid chamber <NUM> of the oil tank <NUM> has an annular shape in the oil tank <NUM>. Therefore, even when a remaining amount of lubricating oil in the liquid chamber <NUM> decreases, the shape of the liquid chamber <NUM> is easily maintained. As a result, the lubricating oil in the liquid chamber <NUM> can be discharged completely. Furthermore, each of the liquid chamber <NUM> and the air chamber <NUM> according to the present embodiment is formed by a single chamber. However, the liquid chamber <NUM> may be formed by plural chambers that are independent from each other, and the air chamber <NUM> may be formed by plural chambers that are independent from each other.

As above, a gas turbine engine according to the present embodiment includes: an oil tank storing lubricating oil; and a cylindrical external case accommodating a compressor, a combustor, and a turbine. The oil tank is arranged along an outer peripheral surface of the external case so as to surround the external case.

Since the gas turbine engine according to the present embodiment is configured as above, the oil tank can be prevented from largely projecting outward in a radial direction. As a result, the gas turbine engine can be reduced in diameter.

Moreover, in the gas turbine engine according to the present embodiment, the oil tank is arranged over an entire circumference of the external case in a circumferential direction of the external case.

Since the gas turbine engine according to the present embodiment is configured as above, a projection amount of the oil tank in the radial direction can be reduced with respect to a necessary amount of lubricating oil. Moreover, when a turbine blade is provided, the scattering of the turbine blade can be surely prevented.

Moreover, the gas turbine engine according to the present embodiment includes a fan that includes fan blades and is accommodated in the external case. The oil tank is arranged at an axial position corresponding to the fan.

Since the gas turbine engine according to the present embodiment is configured as above, a containment ring for antiscattering of the fan blades can be omitted. As a result, the gas turbine engine can be reduced in weight while securing a containment property.

Moreover, in the gas turbine engine according to the present embodiment, the oil tank includes therein: a liquid chamber in which the lubricating oil is sealed, the liquid chamber being expandable and contractable; and an air chamber adjacent to the liquid chamber. When pressure in the air chamber increases, a volume of the liquid chamber decreases, and the lubricating oil in the liquid chamber is discharged.

Since the gas turbine engine according to the present embodiment is configured as above, the lubricating oil can be discharged regardless of the posture of the gas turbine engine.

Moreover, in the gas turbine engine according to the present embodiment, the liquid chamber has an annular shape in the oil tank.

Claim 1:
A gas turbine engine (<NUM>) comprising:
an oil tank (<NUM>) storing lubricating oil;
a cylindrical external case (<NUM>) accommodating a compressor (<NUM>), a combustor (<NUM>), and a turbine (<NUM>); and
a fan (<NUM>) that includes fan blades (<NUM>) and is accommodated in the external case (<NUM>), characterized in that
the oil tank (<NUM>) is arranged along an outer peripheral surface of the external case (<NUM>) so as to surround the external case (<NUM>) and is arranged at an axial position corresponding radially to the axial position of the fan (<NUM>) that is configured to rotate to take in air and supplies the air to the compressor (<NUM>) and a bypass passage (<NUM>) located outside the compressor (<NUM>) in a radial direction.