Patent Description:
Generally, a turbine is a machine which converts energy of a fluid such as water, gas, or steam into mechanical energy. Typically, a turbo machine, in which a plurality of feathers or wings are embedded around a circumferential portion of a rotating body so that the rotating body is rotated at a high speed by impulsive force or reactive force generated by discharging steam or gas to the feathers or wings, is referred to as a turbine.

Such turbines are classified into a water turbine using energy of water located at a high elevation, a steam turbine using energy of steam, an air turbine using energy of high-pressure compressed air, a gas turbine using energy of high-temperature/high-pressure gas, and so forth.

In general, a gas turbine is a kind of internal combustion engine that converts thermal energy into mechanical energy by injecting high-temperature, high-pressure combustion gas generated by mixing fuel with air compressed at high pressure in a compressor and then combusting a mixture of the fuel and air to a turbine to rotate it. Gas turbines are used to drive generators, aircraft, ships and trains.

Since these gas turbines do not have a reciprocating movement mechanism such as a piston of a <NUM>-stroke engine, there is no mutual friction portion such as a piston-cylinder. Therefore, the consumption of lubricating oil is extremely low, the amplitude which is a characteristic of a reciprocating movement mechanism is greatly reduced, and high-speed movement is possible.

A gas turbine includes, as basic elements, a compressor to compress air, a combustor to combust compressed air supplied from the compressor with fuel to produce combustion gas; and a turbine to rotate wings by high-temperature and high-pressure combustion gas injected by the combustor to generate power. The combustion gas injected into the turbine generates rotational force while passing through the turbine vanes and turbine blades, thereby rotating the rotor of a turbine.

The compressor includes a plurality of compressor blades and a plurality of compressor vanes arranged alternately, and compressor blades rotate with a rotor (rotating shaft) of the gas turbine, while compressor vanes are installed on a compressor casing to align the flow of air drawn into the compressor blades.

At this time, the compressor vane may be a shrouded type like a vane <NUM> shown in <CIT>, or a cantilever type like a retaining ring <NUM> and a vane <NUM> shown in <CIT>.

Document <CIT> discloses a vane carrier assembly for supporting vanes within a main engine casing of a gas turbine engine. The vane carrier assembly comprises a plurality of vane support panels positioned adjacent to one another so as to define a vane support assembly. The support panels are assembled such that the support panels expand circumferentially to minimize radial expansion of the vane support assembly during operation of the gas turbine engine. A control ring is coupled to the main engine casing, and the vane support assembly is coupled to the control ring. The control ring may be formed from a material having a coefficient of thermal expansion less than that of the material from which the vane support assembly is formed.

The shrouded type of a compressor vane may be provided with retaining rings on both an outside and an inside of the vane in a radial direction, and the shrouded type may make the vane tip clearance zero. Therefore, the shrouded type may eliminate a leakage flow caused by the tip clearance, but it has a disadvantage of increasing manufacturing cost and time.

The cantilever type may be provided with a retaining ring only on an outside of the vane in a radial direction, and the cantilever type is easier to manufacture and assemble than the shrouded type. However, there is a disadvantage that a leakage flow may occur, because a clearance of a certain value is required to prevent a collision due to a difference in the internal structure caused by thermal expansion during operation.

One of the aims of the present invention is to provide a cantilever type compressor that is easy to manufacture and assemble, but can minimize the vane tip clearance and a gas turbine including such cantilever type compressor. To this end, the present invention provides a compressor in accordance with claim <NUM> and a gas turbine in accordance with claim <NUM>. The above aim specifically is achieved by an elastic member absorbing collision impact and being compressed when the vane collides with the shroud segment due to expansion of the vane. The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those having ordinary skill in the art to which the present invention belongs from the description below.

According to a first aspect of the invention, a compressor includes: a casing; a retaining ring coupled to an inside of the casing; a plurality of cantilever type vanes fastened to an inner circumferential surface of the retaining ring and spaced apart from each other along a circumferential direction of the retaining ring; a diffuser fixed to face an end of a rotor disk installed in an inner space of the casing; a shroud segment movably disposed on the diffuser to face at least one vane tip of the plurality of vanes; and an elastic member installed between the shroud segment and the diffuser.

According to an embodiment, a plurality of dovetail grooves formed to be spaced apart from each other in a circumferential direction may be provided on an inner circumferential surface of the retaining ring, and each of the plurality of vanes may include a dovetail portion fastened to the dovetail grooves; and a wing portion extending from the dovetail portion in a radial direction of the retaining ring.

According to an embodiment, the dovetail portion may include a bottom surface opposing the wing portion; and a pair of tapered surfaces obliquely extending from the bottom surface toward the wing portion such that a width thereof is narrowed toward the wing portion.

According to an embodiment, the shroud segment may consist of a plurality of shroud segments continuously disposed along a circumferential direction of the diffuser, and the elastic member may be composed of a plurality of elastic members disposed between each of the plurality of shroud segments and the diffuser.

According to an embodiment, an engagement protrusion may be formed on one side in a circumferential direction of each of the plurality of shroud segments, and an engagement groove allowing the engagement protrusion of an adjacent shroud segment to be seated therein may be formed on another side in a circumferential direction thereof.

According to an embodiment, a catching protrusion may be formed in the shroud segment, a catching groove allowing the catching protrusion to be seated therein may be formed in the diffuser, and a width of the catching groove may be greater than a thickness of the catching protrusion such that the catching protrusion moves within the catching groove.

According to an embodiment, the shroud segment may include a main body disposed on the diffuser and a pair of leg portions extending from the main body toward the diffuser, and the catching protrusion may be comprised of a pair of catching protrusions, each of which protrudes outward in an axial direction from the pair of leg portions.

According to an embodiment, each of the pair of catching protrusions may protrude in a direction opposite to each other.

According to an embodiment, a sealing member may be interposed between the shroud segment and the diffuser.

According to an embodiment, the compressor may further include: a positioning member having one end fixed to one among the shroud segment and the diffuser and another end movably disposed on the other one among the shroud segments and the diffuser.

According to an embodiment, one end of the positioning member may be fixed to the diffuser, and another end may be disposed in a groove portion formed in the shroud segment.

According to an embodiment, the elastic member may be located on an outside of the positioning member.

According to an embodiment, when the vane collides with or applies force to the shroud segment due to expansion of the vane during operation of the compressor, the elastic member may be compressed while absorbing force.

According to an embodiment, during operation of the compressor, a maximum length radially expandable of the vane may be smaller than a sum of a distance between the vane and the shroud segment and a distance at which the shroud segment is movable on the diffuser.

A second aspect of the invention is related to a gas turbine, including: the compressor to suck and compress air to a high pressure according to any one among the above embodiments; a combustor to mix the air compressed by the compressor with fuel and combust the air-fuel mixture; and a turbine to generate power by rotating a turbine blade using high-temperature, high-pressure combustion gas discharged from the combustor.

According to the present invention, the cantilever type is easy to manufacture and assemble, and when the vane collides with the shroud segment due to expansion of the vane, the elastic member absorbs the impact and is compressed, thereby minimizing the vane tip clearance. As a result, the leakage flow through the tip clearance can be minimized, so that aerodynamic performance can be maximized.

In addition, an axial gap between the shroud segment and the diffuser may be eliminated, and leakage may be prevented by interposing the sealing member.

The advantageous effects of the present invention are not limited to the above effects, and it should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

Hereinafter, exemplary embodiments of a compressor and a gas turbine of the present invention will be described with reference to the accompanying drawings.

In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may be changed according to intention or practices of a user or operator, and the examples below do not limit the scope of the present invention, but are merely illustrative of the components presented in the claims of the present invention.

In order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and the same reference numerals will be used to refer to the same or similar elements throughout the specification. In addition, throughout the specification, unless explicitly described to the contrary, when a component includes/comprises a certain element, the words "include/comprise" will be understood to imply the inclusion of other elements but not the exclusion of any other elements.

First, the configuration of a gas turbine according to an embodiment of the present invention will be described with reference to <FIG>.

A gas turbine <NUM> according to the present invention includes, largely, a casing <NUM>, a compressor <NUM> to suck and compress air to a high pressure, a combustor <NUM> to mix the air compressed by the compressor <NUM> with fuel and combust the mixture of the fuel and the air, and a turbine <NUM> to rotate a rotor <NUM> and generate power by rotational force using combustion gas discharged from the combustor <NUM>.

The casing <NUM> may include a compressor casing <NUM> in which the compressor <NUM> is accommodated, a combustor casing <NUM> in which the combustor <NUM> is accommodated, and a turbine casing <NUM> in which the turbine <NUM> is accommodated. Here, the compressor casing <NUM>, the combustor casing <NUM>, and the turbine casing <NUM> may be sequentially arranged from an upstream side to a downstream side in terms of a fluid flow direction.

Inside the casing <NUM>, a rotor <NUM> is rotatably provided by a bearing along a central axis of the gas turbine <NUM>, and a generator (not illustrated) is interlocked to the rotor <NUM> to generate power.

The rotor <NUM> includes a compressor rotor disk <NUM> accommodated in the compressor casing <NUM>, a turbine rotor disk <NUM> accommodated in the turbine casing <NUM>, and a torque tube <NUM> accommodated in the combustor casing <NUM> and connecting the compressor rotor disk <NUM> and the turbine rotor disk <NUM>. The rotor <NUM> may further include a tie rod <NUM> and a fixing nut <NUM> that fasten the compressor rotor disk <NUM>, the torque tube <NUM>, and the turbine rotor disk <NUM>.

A plurality of the compressor rotor disk <NUM> are formed (for example, <NUM> disk sheets), and the plurality of compressor rotor disks <NUM> may be arranged along an axial direction of the rotor <NUM>. That is, the compressor rotor disk <NUM> may be formed in multiple stages (for example, <NUM> stages). In addition, each compressor rotor disk <NUM> may be formed in an approximate disk shape, and a compressor blade coupling slot may be formed on its outer periphery so that a compressor blade <NUM>, to be described later, may be coupled thereto.

The turbine rotor disk <NUM> may be configured similarly to the compressor rotor disk <NUM>. That is, a plurality of the turbine rotor disks <NUM> are formed, and the plurality of turbine rotor disks <NUM> may be arranged along an axial direction of the rotor <NUM>. That is, the turbine rotor disk <NUM> may be formed in multiple stages. In addition, each turbine rotor disk <NUM> may be formed in an approximate disk shape, and a turbine blade coupling slot may be formed on its periphery so that a turbine blade <NUM>, to be described later, may be coupled thereto.

The torque tube <NUM> is a torque transmission member that transmits rotational force of the turbine rotor disk <NUM> to the compressor rotor disk <NUM>. One end of the torque tube <NUM> may be fastened to the compressor rotor disk located at a most downstream end in a flow direction of air among the plurality of compressor rotor disks <NUM>, and the other end of the torque <NUM> may be fastened to the turbine rotor disk <NUM> located at a most upstream end in a flow direction of combustion gas among the plurality of turbine rotor disks <NUM>. Here, projections are formed on the one end and the other end of the torque tube <NUM>, respectively, and each of the compressor rotor disks <NUM> and the turbine rotor disks <NUM> has a protrusion and a groove meshing with the protrusion such that relative rotation of the torque tube <NUM> with respect to the compressor rotor disk <NUM> and the turbine rotor disk <NUM> can be prevented.

In addition, the torque tube <NUM> may be formed in a hollow cylinder shape such that air supplied from the compressor <NUM> passes through the torque tube <NUM> and flows to the turbine <NUM>. At this time, the torque tube <NUM> may be formed to be resistant to deformation and twisting due to the characteristics of the gas turbine that is continuously operated for a long time, and may be formed to be easily assembled and disassembled for easy maintenance.

The tie rod <NUM> may be formed to penetrate the plurality of compressor rotor disks <NUM>, the torque tube <NUM> and the plurality of turbine rotor disks <NUM>. One end of the tie rod <NUM> may be fastened into the compressor rotor disk located at a most upstream end in a flow direction of air among the plurality of compressor rotor disks <NUM>. The other end of the tie rod <NUM> may protrude through an opposite side of the compressor <NUM> toward the turbine rotor disk <NUM> located at a most downstream end in a flow direction of the combustion gas, and may be fastened to the fixing nut <NUM>.

Here, the fixing nut <NUM> presses the turbine rotor disk <NUM> located at the downstream end toward the compressor <NUM> side, and as a result, the plurality of compressor rotor disks <NUM>, the torque tube <NUM>, and the plurality of turbine rotor disks <NUM> may be compressed in an axial direction of the rotor <NUM>. Accordingly, axial movement and relative rotation of the plurality of compressor rotor disks <NUM>, the torque tube <NUM>, and the plurality of turbine rotor disks <NUM> may be prevented.

In the meantime, in the embodiment of the present invention, one tie rod is provided, but the present invention is not limited thereto. In other embodiments of the present invention, separate tie rods may be provided on the compressor side and the turbine side, respectively, or a plurality of tie rods may be radially arranged along a circumferential direction.

The compressor <NUM> may include the compressor blade <NUM> rotating together with the rotor <NUM> and a compressor vane <NUM> installed on the compressor casing <NUM> to align a flow of air drawn into the compressor blade <NUM>.

A plurality of compressor blades <NUM> may be formed. The plurality of compressor blades <NUM> may be formed in multiple stages along an axial direction of the rotor <NUM>. The plurality of compressor blades <NUM> may be radially disposed along a rotational direction of the rotor <NUM> for respective stages. The rotational directional may be referred to as a circumferential direction throughout this specification. A root portion <NUM> of the compressor blade <NUM> is coupled to the compressor blade coupling slot of the compressor rotor disk <NUM>. The root portion <NUM> may be formed in a fir-tree shape or a dovetail shape to prevent the compressor blade <NUM> from being separated from the compressor blade coupling slot in a radial direction of the rotor <NUM>. At this time, the compressor blade coupling slot is formed to correspond to the root portion <NUM> of the compressor blade.

Here, the compressor rotor disk <NUM>" and'the compressor blade <NUM> may be generally coupled in a tangential type or an axial type scheme. In the embodiment of the present invention, the compressor blade root portion <NUM> is formed in a so-called axial type scheme in which the compressor blade root portion <NUM> is inserted into the compressor blade coupling slot along the axial direction of the rotor <NUM>. Accordingly, in the present embodiment, a plurality of compressor blade coupling slots are formed and radially arranged along a circumferential direction of the compressor rotor disk <NUM>.

A plurality of the compressor vane <NUM> are formed. The plurality of compressor vanes <NUM> may be formed in multiple stages along the axial direction of the rotor <NUM>. Here, the compressor vane <NUM> and the compressor blade <NUM> may be alternately arranged along the air flow direction. In addition, the plurality of compressor vanes <NUM> may be disposed radially along the rotational direction of the rotor <NUM> for respective stages. In one embodiment, at least one of the plurality of compressor vanes <NUM> may be mounted to be rotatable within a predetermined range for the purpose of adjusting an inflow of air.

The combustor <NUM> creates a high-energy, high-temperature, high-pressure combustion gas by mixing air introduced from the compressor <NUM> with fuel and combusting the mixture of the air and fuel to generate a combustion gas. During this process, an isobaric combustion process may be performed to raise the combustion gas temperature to a heat resistance limit that the combustor and turbine can withstand. A plurality of the combustor <NUM> may be formed. The plurality of combustors <NUM> may be arranged along a rotational direction of the rotor <NUM> in a combustor casing <NUM>.

Each combustor <NUM> includes a liner into which compressed air from the compressor <NUM> is introduced, and a transition piece positioned at a rear of the liner to guide combustion gas to the turbine <NUM>. The liner and the transition piece form a combustion chamber therein, and a sleeve is arranged to surround the liner and the transition piece to form an annular flow space therebetween.

In addition, each combustor <NUM> may further include a fuel injection nozzle provided at a front of the liner to mix compressed air supplied from the compressor <NUM> and fuel and inject the mixture. Each combustor <NUM> may further include a spark plug provided in a wall portion of the liner to ignite the mixture of the compressed air and fuel in the combustion chamber. Afterwards, the burnt gas, which may be referred to as combustion gas, is discharged to the turbine <NUM> to generate rotation.

At this time, it is important to cool the liner and the transition piece exposed to the high-temperature and high-pressure combustion gas to increase the durability of the combustor. To this end, a cooling hole may be formed in the sleeve so that the compressed air flowing through the cooling hole vertically collides with an outer wall of the liner and the transition piece to cool the liner and the transition piece. Specifically, the compressed air introduced from the compressor <NUM> may flow into the annular space through the cooling hole formed in the sleeve, cool the liner and the transition piece, flow forward of the liner along the annular space, and flow into the fuel injection nozzle.

Here, a de-swirler serving as a guide vane may be formed between the compressor <NUM> and the combustor <NUM> so as to adjust a flow angle at which air is drawn into the combustor <NUM>, to a designed flow angle.

Next, the turbine <NUM> may be configured in a manner similar to that of the compressor <NUM>. The turbine <NUM> may include turbine blades <NUM> rotating together with the rotor <NUM> and turbine vanes <NUM> fixedly mounted to the turbine casing <NUM> to align a flow of air to be drawn onto the turbine blades <NUM>.

A plurality of the turbine blades <NUM> may be formed. The plurality of turbine blades <NUM> may be formed in multiple stages along the axial direction of the rotor <NUM>, and the plurality of turbine blades <NUM> may be formed radially along a rotational direction of the rotor <NUM> for respective stages. A root portion <NUM> of the turbine blades <NUM> is coupled to the turbine blade coupling slot of the turbine rotor disk <NUM>. The root portion <NUM> may be formed in a fir-tree shape or a dovetail shape. At this time, the turbine blade coupling slot is formed to correspond to the root portion <NUM> of the turbine blade.

A plurality of the turbine vanes <NUM> may be formed. The plurality of turbine vanes <NUM> may be formed in multiple stages along an axial direction of the rotor <NUM>. Here, the turbine vanes <NUM> and the turbine blades <NUM> may be alternately arranged along the air flow direction. In addition, the plurality of turbine vanes <NUM> may be disposed radially along a rotational direction of the rotor <NUM> for respective stages.

Here, unlike the compressor <NUM>, the turbine <NUM> is in contact with high-temperature and high-pressure combustion gas, so the turbine <NUM> requires a cooling unit to prevent damage such as thermal deterioration. To this end, the turbine <NUM> may include a cooling passage for bleeding compressed air from some parts of the compressor <NUM> and supplying the compressed air to the turbine <NUM>. Depending on the embodiment, the cooling passage may extend from an outside of the casing <NUM> (external passage) or may extend by penetrating an inside of the rotor <NUM> (internal passage), or both the external and internal passages may be used.

At this time, the cooling passage may communicate with a turbine blade cooling passage formed inside the turbine blade <NUM>, so that the turbine blade <NUM> can be cooled by cooling air. In addition, the turbine blade cooling passage may communicate with the turbine blade film cooling hole formed on a surface of the turbine blade <NUM>, so that the cooling air is supplied to the surface of the turbine blade <NUM>. Thereby, the turbine blade <NUM> may be, so-called, film-cooled by the cooling air. Similar to the turbine blades <NUM>, the turbine vanes <NUM> may also be formed to be cooled by receiving cooling air from the cooling passage.

Here, the above gas turbine is merely one embodiment of the present invention. Now, an embodiment of the compressor of the present invention will be described in more detail below. It is understood that the embodiment of the compressor of the present invention may be widely applied to jet engines in which air and fuel are combusted as well as to general gas turbines.

Next, referring to <FIG>, the compressor <NUM> according to the embodiment of the present invention is described. In particular, a structure in which the compressor vane <NUM> of the last stage of the compressor is installed will be described as an embodiment of the present invention.

As illustrated in <FIG>, the plurality of compressor vanes <NUM> is disposed at respective stages of the compressor <NUM>. The plurality of compressor vanes <NUM> are fastened to an inner circumferential surface of the retaining ring <NUM> along a circumferential direction of the retaining ring <NUM>, and are spaced apart from each other.

To this end, according to an embodiment, a plurality of dovetail grooves <NUM> formed to be spaced apart from each other along a circumferential direction are provided on an inner circumferential surface of the retaining ring <NUM>. In addition, each of the plurality of compressor vanes <NUM> includes a dovetail portion <NUM> fastened to the dovetail groove <NUM> and a wing portion <NUM> extending in a radially inward direction of the retaining ring <NUM> from the dovetail portion <NUM>. The wing portion <NUM> may be referred to, alternatively, as an airfoil portion <NUM>.

Specifically, according to an embodiment, each of the dovetail portions <NUM> may include a bottom surface 242a opposing the wing portion <NUM> and tapered surfaces 242b on both sides extending toward the wing portion <NUM> while facing each other, but extending obliquely toward each other such that a width of the dovetail portions <NUM> is narrowed toward the wing portion <NUM>. Accordingly, the dovetail portion <NUM> of each compressor vane may be fitted into and fastened to the dovetail groove <NUM> of the retaining ring, and be fixed so as not to be separated in a radial direction of the retaining ring <NUM>. The dovetail portion <NUM> of each compressor vane may be inserted into the dovetail groove <NUM> in an axial direction of the rotor <NUM>.

In addition, the retaining ring <NUM> of each stage may be directly or indirectly coupled to an inside of the compressor casing <NUM>. As illustrated in <FIG>, according to an embodiment, one or more vane carriers <NUM> are installed inside the compressor casing <NUM>. The retaining ring <NUM> disposed at a front stage of the compressor may be directly coupled to an inside of the compressor casing <NUM>, and the retaining ring <NUM> disposed at a rear stage of the compressor may be indirectly coupled to an inside of the compressor casing <NUM> via the vane carrier <NUM>. To this end, a retaining engagement groove <NUM> may be formed to engage the retaining ring <NUM> on an inner circumferential surface of the compressor casing <NUM> or the vane carrier <NUM>. The retaining ring <NUM> may be formed to have a cross section having a shape corresponding to the retaining engagement groove <NUM> such that the retaining ring <NUM> can be fitted into and engaged with the retaining engagement groove <NUM>.

As illustrated in <FIG>, according to an embodiment, radial inner ends (i.e., tips) of the plurality of compressor vanes <NUM> disposed at the last stage of the compressor oppose the diffuser <NUM>. The diffuser <NUM> may be disposed radially outward of the torque tube <NUM>, and be fixed at a predetermined interval so as to face an end of the compressor rotor disk <NUM>. That is, the compressor rotor disk <NUM> rotates while the diffuser <NUM> does not rotate. The diffuser <NUM> serves to guide compressed air from the compressor <NUM> to the combustor casing <NUM> by connecting an outlet of the compressor <NUM> and an inlet of the combustor casing <NUM> in which the combustor <NUM> is disposed.

According to the invention, a shroud segment <NUM> is movably disposed on the diffuser <NUM>, and the shroud segment <NUM> faces at least one compressor vane <NUM> among the plurality of compressor vanes <NUM>. As illustrated in <FIG>, according to an embodiment, a plurality of shroud segments <NUM> are continuously arranged along a circumferential direction of the diffuser <NUM>, and each shroud segment <NUM> faces two compressor vanes <NUM>. At this time, the shroud segments <NUM> adj acent to each other may be in meshing engagement to each other. That is, in each of the plurality of shroud segments <NUM>, an engagement protrusion <NUM> may be formed on one side in a circumferential direction facing the adjacent shroud segment, and an engagement groove <NUM> on which the engagement protrusion <NUM> can be seated may be formed on the other side in the circumferential direction. The shape of the engagement protrusion <NUM> may be formed to correspond to the engagement grove <NUM>. Accordingly, the engagement protrusion <NUM> formed on one side of the shroud segment <NUM> in the circumferential direction may be seated and engaged with the engagement groove <NUM> formed on the other side of the adjacent shroud segment <NUM> in the circumferential direction.

In addition, as illustrated in <FIG>, according to an embodiment, a pair of catching protrusions <NUM> protruding outward in an axial direction are formed on the shroud segment <NUM>, and a pair of catching grooves <NUM> on which the pair of catching protrusions <NUM> are seated are formed on the diffuser <NUM>. In particular, a width w1 of the catching groove <NUM> in the radial direction may be larger than a thickness t1 of the catching protrusion <NUM> in the radial direction, so that the catching protrusion <NUM> may be movable in a vertical direction in <FIG>, i.e., the radial direction, within the catching groove <NUM>.

More specifically, according to an embodiment, the shroud segment <NUM> may include a main body <NUM> disposed on the diffuser <NUM>, a pair of leg portions <NUM> extending from the main body <NUM> toward the diffuser <NUM>, i.e., toward a radially inward direction, and the pair of catching protrusions <NUM> at each of the radially inward ends of the pair of leg portions <NUM>, each of which protruding from the pair of leg portions <NUM> toward the axial direction. Here, the pair of catching protrusions <NUM> protrude in opposite directions from each other, thereby obtaining structural stability and reducing vibration. In other words, one of the pair of catching protrusions <NUM> protrudes in the upstream direction and the other of the pair of catching protrusions <NUM> protrude in the downstream direction.

According to the invention, an elastic member <NUM> is installed between the shroud segment <NUM> and the diffuser <NUM> opposing to the shroud segment <NUM>. The elastic member <NUM> may be disposed between the shroud segment <NUM> and the diffuser <NUM> in the radial direction. The elastic member <NUM> may apply pushing force against the shroud segment <NUM> and the diffuser <NUM>, pushing them away from each other. In other words, the elastic member <NUM> may apply a force pushing the shroud segment <NUM> in the radially outward direction. In this embodiment, since a plurality of the shroud segments <NUM> are formed, a plurality of the elastic member <NUM> may also be formed and disposed between each of the plurality of shroud segments <NUM> and the diffuser <NUM>. According to an embodiment, the elastic member <NUM> may be formed as a spring.

According to an embodiment, a radially inner end of the compressor vane <NUM> and the shroud segment <NUM> are in contact with each other in a steady state or a minimum gap may be formed therebetween. This is because, when a minimum gap is formed between the radially inner end of the compressor vane <NUM> and the shroud segment <NUM>, even if the compressor vane <NUM> collides with the shroud segment <NUM> due to expansion of the compressor vane <NUM> as temperature rises during operation, the elastic member <NUM> may be compressed and may absorb the shock. So, due to the elastic member <NUM>, compressor vane <NUM> is not worn by the collision or contact between the shroud segment <NUM> and the compressor vane <NUM> and vibration due to such collision or contact does not occur or is minimized. Similarly, even when the radially inner end of the compressor vane <NUM> and the shroud segment <NUM> are installed in contact with each other, when the compressor vane <NUM> expands as the temperature rises during operation and the compressor vane <NUM> applies force to the shroud segment <NUM>, the elastic member <NUM> may be compressed and absorb the force. Accordingly, according to embodiments of the present invention, even though the compressor vane is in the cantilever type having only retaining rings outside of the vane, the vane tip clearance can be minimized, and ultimately, a leakage flow through the tip clearance of the cantilever type can also be minimized, thereby maximizing aerodynamic performance. Therefore, embodiments of the present invention may achieve both advantages - an advantage of easy manufacturing and assembly and an advantage of minimized vane tip clearance.

Moreover, according to an embodiment, a sealing member <NUM> may be interposed between the shroud segment <NUM> and the diffuser <NUM>. The sealing member <NUM> may be disposed between the shroud segment <NUM> and the diffuser <NUM> in the axial direction. In one embodiment, the sealing member <NUM> is interposed between at one of the leg portions <NUM> of the shroud segment and the diffuser <NUM> opposing the leg portion <NUM>. Accordingly, an axial gap between the shroud segment <NUM> and the diffuser <NUM> may be eliminated and leakage may be prevented.

Furthermore, according to an embodiment, a positioning member <NUM> may be further provided, having one end fixed to one among the shroud segments <NUM> and the diffuser <NUM> and the other end movably disposed on the other one among the shroud segment <NUM> and the diffuser <NUM>. In one embodiment, one end of the positioning member <NUM> is fixed to the diffuser <NUM>, and the other end is movably disposed on the shroud segment <NUM>. To this end in this embodiment, in the shroud segment <NUM>, more specifically, in a lower portion of the main body <NUM> of the shroud segment <NUM>, a groove portion <NUM> extending in a vertical direction in the figure may be formed, in other words, in a radially outward direction from an inner surface of the main body <NUM>. So, according to this embodiment, while one end of the position member <NUM> is fixed to the diffuser <NUM>, the other end of the positioning member <NUM> may be placed within the groove portion <NUM>. Accordingly, when the shroud segment <NUM> moves along with compression and tension of the elastic member <NUM> in the radial direction, the position of the diffuser <NUM> may be maintained without being shaken. In one embodiment, the positioning member <NUM> may be formed as a screw and be coupled to a coupling hole of the diffuser <NUM> by screw coupling. According to an embodiment, the elastic member <NUM> formed as a coil spring may be positioned so as to be wound around at least a part of an outside of the positioning member <NUM>.

However, the present invention is not limited to the above embodiment, and the positioning member <NUM> may be omitted. For example, without the positioning member, an elastic member formed as a plate spring may be installed between the shroud segment <NUM> and the diffuser <NUM> to obtain the same effect of the above embodiment.

In addition, as described above, the maximum length that the compressor vane <NUM> can radially expands is preferably smaller than a sum of a distance (i.e., clearance) between the compressor vane <NUM> and the shroud segment <NUM> and a distance at which the shroud segment <NUM> can move in the radial direction with respect to the diffuser <NUM>. In other words, the distance between the compressor vane <NUM> and the shroud segment <NUM> and the distance at which the shroud segment <NUM> can move in the radial direction with respect the diffuser <NUM> may be configured to be larger than the maximum length that the compressor vane <NUM> can radially expands during the operation of the compressor. It is to ensure the elastic member <NUM> sufficiently absorb the force applied to the shroud segment <NUM>, when the compressor vane <NUM> expands according to the temperature rise during compressor operation. In this embodiment, the distance at which the shroud segment <NUM> can move in the radial direction with respect to the diffuser <NUM> may be determined as the smallest value among a radial distance between the main body <NUM> of the shroud segment <NUM> and the diffuser <NUM> facing the main body <NUM>, a radial distance between the catching groove <NUM> and the catching protrusion <NUM>, and a radial distance between a radial distal end of the positioning member <NUM> and a radial distal end of the groove portion <NUM> radially corresponding to the radial distal end of the position member <NUM>. If the distance between the main body <NUM> of the shroud segment <NUM> and the diffuser <NUM> facing the main body <NUM>, the distance between the catching groove <NUM> and the catching protrusion <NUM>, and the distance between a distal end of the positioning member <NUM> and a distal end of the groove portion <NUM> are all the same, the value may be decided as the distance at which the shroud segment <NUM> can move on the diffuser <NUM>.

Claim 1:
A compressor (<NUM>), comprising:
a casing (<NUM>);
a retaining ring (<NUM>) coupled to an inside of the casing (<NUM>);
a plurality of cantilever type vanes (<NUM>) fastened to an inner circumferential surface of the retaining ring (<NUM>) and spaced apart from each other along a circumferential direction of the retaining ring (<NUM>);
a diffuser (<NUM>) fixed to face an end of a rotor disk (<NUM>) installed in an inner space of the casing (<NUM>); characterised in that it further comprises
a shroud segment (<NUM>) movably disposed on the diffuser (<NUM>) to face at least one vane tip of the plurality of vanes (<NUM>); and
an elastic member (<NUM>) installed between the shroud segment (<NUM>) and the diffuser (<NUM>).