Seal assembly for gas turbine engine

Abstract

A seal assembly includes a plurality of seal segments. Each seal segment of the plurality of seal segments includes a main body having a first end and a second end, a tongue extending from the first end to a first outmost end, and a groove extending from the second end to a second outmost end, the groove having a base plate, a first wall, and a second wall, the tongue of an adjacent seal segment inserted into the groove and positioned between the first wall and the second wall.

Description

SEAL ASSEMBLY FOR GAS TURBINE ENGINEBACKGROUND

[0001] A gas turbine engine typically includes a compressor section, a turbine section, and a combustion section disposed therebetween. The compressor section includes multiple stages of rotating compressor blades and stationary compressor vanes to produce compressed air. The combustion section typically includes a plurality of combustors to produce hot working flow by combusting the air-fuel mixture. The turbine section includes multiple stages of rotating turbine blades and stationary turbine vanes for the expansion of the hot gas and conversion of fluid energy to mechanical energy. A plurality of seal assemblies are arranged between adjacent components of the gas turbine engine to reduce leakage of fluid, such as the compressed air, the hot working flow, and the cooling fluid. The reduction of fluid leakage improves efficiency of the gas turbine engine.BRIEF SUMMARY

[0002] In one aspect, a seal assembly is provided. The seal assembly includes a plurality of seal segments. Each seal segment of the plurality of seal segments includes a main body having a first end and a second end, a tongue extending from the first end to a first outmost end, and a groove extending from the second end to a second outmost end, the groove having a base plate, a first wall, and a second wall, the tongue of an adjacent seal segment inserted into the groove and positioned between the first wall and the second wall.

[0003] In one aspect, an engine is provided. The engine includes a first component having a first slot and a cutout. The engine also includes a second component adjacent to the first component, the second component having a second slot facing to the first slot. The enginealso includes a seal assembly positioned between the first component and the second component and inserted into the first slot and the second slot. The seal assembly includes a plurality of seal segments. Each seal segment of the plurality of seal segments includes a main body having a first end and a second end, a tongue extending from the first end to a first outmost end, a groove extending from the second end to a second outmost end, the groove having a base plate, a first wall inserted into the first slot, and a second wall inserted into the second slot, the tongue of an adjacent seal segment inserted into the groove and positioned between the first wall and the second wall, and a hook formed at the second outmost end and positioned into the cutout.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0005] FIG. 1 is a longitudinal cross-sectional view of a gas turbine engine taken along a plane that contains a longitudinal axis or central axis.

[0006] FIG. 2 is a partial perspective view of a seal assembly for use in the gas turbine engine of FIG. 1.

[0007] FIG. 3 is a perspective view of a seal segment of the seal assembly of FIG. 2.

[0008] FIG. 4 is a perspective view of a tongue of the seal segment of FIG. 3.

[0009] FIG. 5 is a perspective view of a groove of the seal segment of FIG. 3.

[0010] FIG. 6 is a perspective view of an overlapping area between two adjacent seal segments of FIG. 2.

[0011] FIG. 7 is a section view of the seal assembly positioned in the gas turbine engine ofFIG. 1.

[0012] FIG. 8 is a partial perspective view of the seal assembly positioned in the gas turbine engine of FIG. 1.

[0013] FIG. 9 is an enlarged section view of a portion of the gas turbine engine of FIG. 1.DETAILED DESCRIPTION

[0014] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0015] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0016] Also, it should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including”, “having”, and “comprising”, as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an”, and “the” are intended to include theplural forms as well, unless the context clearly indicates otherwise. Further, the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, any features, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0017] Also, although the terms “first”, “second”, “third” and so forth may be used herein to refer to various elements, information, functions, or acts, these elements, information, functions, or acts should not be limited by these terms. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0018] Also, in the description, the terms “axial” or “axially” refer to a direction along a longitudinal axis of a gas turbine engine. The terms “radial” or “radially” refer to a direction perpendicular to the longitudinal axis of the gas turbine engine. The terms “downstream” or “aft” refer to a direction along a flow direction. The terms “upstream” or “forward” refer to a direction against the flow direction.

[0019] In addition, the term “adjacent to" may mean that an element is relatively near to but not in contact with a further element or that the element is in contact with the further portion, unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that arewithin normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0020] FIG. 1 illustrates an example of a gas turbine engine 100 including a compressor section 102, a combustion section 104, and a turbine section 106 arranged along a central axis 112. The compressor section 102 includes a plurality of compressor stages 114 with each compressor stage 114 including a set of stationary compressor vanes 116 or adjustable guide vanes and a set of rotating compressor blades 118. A rotor 134 supports the rotating compressor blades 118 for rotation about the central axis 112 during operation. In some constructions, a single one-piece rotor 134 extends the length of the gas turbine engine 100 and is supported for rotation by a bearing at either end. In other constructions, the rotor 134 is assembled from several separate spools that are attached to one another or may include multiple disk sections that are attached via a bolt or plurality of bolts.

[0021] The compressor section 102 is in fluid communication with an inlet section 108 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 102. During operation of the gas turbine engine 100, the compressor section 102 draws in atmospheric air and compresses that air for delivery to the combustion section 104. The illustrated compressor section 102 is an example of one compressor section 102 with other arrangements and designs being possible.

[0022] In the illustrated construction, the combustion section 104 includes a plurality of separate combustors 120 that each operate to mix a flow of fuel with the compressed air from the compressor section 102 and to combust that air-fuel mixture to produce a flow of high temperature, high pressure combustion gases or exhaust gas 122. Of course, many other arrangements of the combustion section 104 are possible.

[0023] The turbine section 106 includes a plurality of turbine stages 124 with each turbine stage 124 including a number of stationary turbine vanes 126 and a number of rotating turbine blades 128. The turbine stages 124 are arranged to receive the exhaust gas 122 from the combustion section 104 at a turbine inlet 130 and expand that gas to convert thermal and pressure energy into rotating or mechanical work. The turbine section 106 is connected tothe compressor section 102 to drive the compressor section 102. For gas turbine engines 100 used for power generation or as prime movers, the turbine section 106 is also connected to a generator, pump, or other device to be driven. As with the compressor section 102, other designs and arrangements of the turbine section 106 are possible.

[0024] An exhaust portion 110 is positioned downstream of the turbine section 106 and is arranged to receive the expanded flow of exhaust gas 122 from the final turbine stage 124 in the turbine section 106. The exhaust portion 110 is arranged to efficiently direct the exhaust gas 122 away from the turbine section 106 to assure efficient operation of the turbine section 106. Many variations and design differences are possible in the exhaust portion 110. As such, the illustrated exhaust portion 110 is but one example of those variations.

[0025] A control system 132 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters and to control various operations of the gas turbine engine 100. In preferred constructions the control system 132 is typically micro-processor based and includes memory devices and data storage devices for collecting, analyzing, and storing data. In addition, the control system 132 provides output data to various devices including monitors, printers, indicators, and the like that allow users to interface with the control system 132 to provide inputs or adjustments. In the example of a power generation system, a user may input a power output set point and the control system 132 may adjust the various control inputs to achieve that power output in an efficient manner.

[0026] The control system 132 can control various operating parameters including, but not limited to variable inlet guide vane positions, fuel flow rates and pressures, engine speed, valve positions, generator load, and generator excitation. Of course, other applications may have fewer or more controllable devices. The control system 132 also monitors various parameters to assure that the gas turbine engine 100 is operating properly. Some parameters that are monitored may include inlet air temperature, compressor outlet temperature and pressure, combustor outlet temperature, fuel flow rate, generator power output, bearing temperature, and the like. Many of these measurements are displayed for the user and are logged for later review should such a review be necessary.

[0027] FIG. 2 illustrates a partial perspective view of the seal assembly 200 for use in the gas turbine engine 100 of FIG. 1. The seal assembly 200 can be positioned between two adjacent components in the gas turbine engine 100.

[0028] The seal assembly 200 includes a plurality of seal segments 202 that overlap each other at the ends forming a shiplap. FIG. 2 only illustrates two seal segments 202 overlapping each other in the circumferential direction. It is understood that the seal assembly 200 includes more than two seal segments 202 that are assembled to circumferentially surround the rotor 134.

[0029] FIG. 3 illustrates a perspective view of the seal segment 202. The seal segment 202 includes a main body 302 having a first end 304, a second end 306, a first surface 308, a second surface 310, a first side 312, and a second side 314. A width of the main body 302 is defined as the shortest distance between the first side 312 and the second side 314. A thickness of the main body 302 is defined as the shortest distance between the first surface 308 and the second surface 310. The first surface 308 and the second surface 310 are curved to form an inner surface and an outer surface of a hollow cylinder that surround the rotor 134.

[0030] A tongue 316 extends from the first end 304 to a first outmost end 318. A groove 320 extends from the second end 306 to a second outmost end 322. A hook 324 is formed at the second outmost end 322 and bent to the second surface 310.

[0031] FIG. 4 illustrates a perspective view of the tongue 316. The tongue 316 includes a first surface 402 that extends from the first surface 308 of the main body 302 and a second surface 404 that is positioned at a distance from the second surface 310 of the main body 302 such that a thickness of the tongue 316 is less than a thickness of the main body 302. The thickness of the tongue 316 is defined as the shortest distance between the first surface 402 and the second surface 404. The first surface 402 of the tongue 316 and the first surface 308 of the main body 302 define one continuous surface. The tongue 316 includes a first side 406 that is positioned at a distance from the first side 312 of the main body 302 and a second side 408 that is positioned at a distance from the second side 314 of the main body 302 such that a width of the tongue 316 is less than the width of the main body 302.The width of the tongue 316 is defined as the shortest distance between the first side 406 and the second side 408.

[0032] The tongue 316 includes a first chamfer 410 formed at a first edge between the first side 406 and the first outmost end 318 and a second chamfer 412 formed at a second edge between the second side 408 and the first outmost end 318. The first chamfer 410 has a first angle with the first side 406 and the second chamfer 412 has a second angle with the second side 408. Each of the first angle and the second angle is between 25 degrees to 35 degrees, with other degrees possible. The first angle and the second angle are identical to each other. In other constructions, the first angle and the second angle may be different from each other.

[0033] The tongue 316 includes a third chamfer 414 formed at a third edge between the first surface 402 and the first outmost end 318 and a fourth chamfer 416 formed at a fourth edge between the second surface 404 and the first outmost end 318. The third chamfer 414 has a third angle with the first surface 402 and the fourth chamfer 416 has a fourth angle with the second surface 404. Each of the third angle and the fourth angle is between 5 degrees to 25 degrees, with other degrees possible. The third angle and the fourth angle are identical to each other. In other constructions, the third angle and the fourth angle may be different from each other.

[0034] A plurality of teeth 418 is formed at the second surface 310 and extends away from the first surface 308. The teeth 418 extends from the first end 304 to the second outmost end 322 (shown in FIG. 5) and continuously extends to the hook 324 (shown in FIG. 6). In other constructions, the seal segment 202 may not have the plurality of teeth 418 at the second surface 310.

[0035] FIG. 5 illustrates a perspective view of the groove 320. The groove 320 includes a base plate 502, a first wall 504, and a second wall 506. The base plate 502 extends from the second surface 310 of the main body 302 and has a thickness that is less than the thickness of the main body 302. The first wall 504 is coupled to the base plate 502 and positioned at the first side 312 of the main body 302 and the second wall 506 is coupled to the base plate 502 and positioned at the second side 314 of the main body 302 such that a width of the groove 320 is less than the width of the main body 302. The width of the groove 320 isdefined as the shortest distance between the first wall 504 and the second wall 506. The first wall 504 and the second wall 506 are perpendicular to the base plate 502. In other constructions, the first wall 504 and the second wall 506 may have an angle between 80 degrees to 100 degrees with the base plate 502, with other dimensions possible.

[0036] The hook 324 extends from one side of the main body 302 toward the other side of the main body 302 such that a width of the hook 324 is less than the width of the main body 302. In the construction illustrated in FIG. 5, the hook 324 extends from the second side 314 toward the first side 312. In other constructions, the hook 324 may extends from the first side 312 toward the second side 314. It is also possible that the hook 324 may extends from one side of the main body 302 to the other side of the main body 302 such that a width of the hook 324 equals the width of the main body 302. The hook 324 is bent from the base plate 502 to the second surface 310 and perpendicular to the second surface 310. In other constructions, the hook 324 may have an angle between 80 degrees to 100 degrees with the second surface 310, with other dimensions possible. A fillet 508 is formed at an interface with the second surface 310. The fillet 508 has a radius between 1 mm to 4 mm, with other dimensions possible.

[0037] FIG. 6 illustrates a partial perspective view of the seal assembly 200 showing a shiplap between two adjacent seal segments 202 in an assembled condition. In the assembled condition, the tongue 316 of one seal segment 202 is inserted into the groove 320 of the adjacent seal segment 202 forming the shiplap between two adjacent seal segments 202. The tongue 316 is positioned between the first wall 504 and the second wall 506. A gap 602 is formed within the groove 320 and between the first outmost end 318 of one seal segment 202 and the second end 306 of the adjacent seal segment 202. The gap 602 is closed by the first wall 504 from the first side 312 and closed by the second wall 506 from the second side 314.

[0038] FIG. 7 illustrates a section view of the seal assembly 200 positioned in the gas turbine engine 100. The gas turbine engine 100 includes a first component 702 and a second component 704 that abut to each other with a space 706 therebetween. One side of the first component 702 and the second component 704 are exposed to a low pressure region712. The other side of the first component 702 and the second component 704 are exposed to a high pressure region 714. The low pressure region 712 may be a hot side for a hot working fluid, such as the exhaust gas 122 from the combustion section 104. The high pressure region 714 may be a cold side for a cooling flow, such as the compressed air from the compressor section 102.

[0039] The first component 702 includes a first slot 708. The second component 704 includes a second slot 710 that faces to the first slot 708. The seal assembly 200 is positioned between the first component 702 and the second component 704. The first wall 504 is inserted in the first slot 708 and the second wall 506 is inserted in the second slot 710. The tongue 316 is positioned between the first wall 504 and the second wall 506. The first surface 308 and the tongue 316 face to the low pressure region 712. The second surface 310 and the base plate 502 face to the high pressure region 714.

[0040] A flow 716 may flow into the space 706 from the high pressure region 714 and enters the first slot 708 and the second slot 710. The first wall 504 and the second wall 506 close the gap 602 in the first slot 708 and the second slot 710 to reduce the flow 716 leaking from the first slot 708 and the second slot 710 into the gap 602 and to the low pressure region 712.

[0041] FIG. 8 illustrates a partial perspective view of the seal assembly 200 positioned in the gas turbine engine 100. For illustration purpose, the plurality of second components 704 are not shown in FIG. 8 and only two partial first components 702 and two partial seal segments 202 are shown in FIG. 8. The plurality of first components 702 are circumferentially arranged around the central axis 112 and surround the rotor 134. The plurality of first components 702 are spaced apart from each other.

[0042] The first component 702 has a cutout 802 formed at a side facing to the adjacent first component 702. The hook 324 of the seal segment 202 is inserted into the cutout 802 to inhibit a rotation of the seal assembly 200 during operation. In other constructions, the second component 704 may have a cutout 802 formed at a side facing to the adjacent second component 704. The hook 324 of the seal segment 202 may be inserted into the cutout 802of the second component 704 to inhibit the rotation of the seal assembly 200 during operation.

[0043] FIG. 9 illustrates an enlarged section view of a portion 900 of the gas turbine engine 100. With reference to FIG. 1, the gas turbine engine 100 includes a plurality of vane platforms 902, a plurality of ring segments 904, and a carrier 906. Each vane platform 902 of the plurality of vane platforms 902 is attached to a respective stationary turbine vane 126. Each ring segment 904 of the plurality of ring segments 904 is positioned radially adjacent to a tip of the rotating turbine blade 128 and axially adjacent to a respective vane platform 902. The vane platform 902 is positioned radially adjacent to the carrier 906 and is supported by the carrier 906.

[0044] The seal assembly 200 illustrated in FIG. 2 to FIG. 8 is an axial seal assembly that is positioned between two axially adjacent components. As illustrated in FIG. 9, the first component 702 is the vane platform 902 and the second component 704 is the ring segment 904. The seal assembly 200 is positioned between the vane platform 902 and the ring segment 904. In this arrangement, the seal assembly 200 has a hollow conical shape with respect to the central axis 112 and surrounds the rotor 134. The first surface 308 is an inner surface of the hollow cone and the second surface 310 is an outer surface of the hollow cone.

[0045] With reference to FIG. 1, the gas turbine engine 100 also includes a plurality of axially adjacent rotor disks 136 that are connected to the rotor 134. Each rotor disk 136 of the plurality of rotor disks 136 supports a respective rotating turbine blade 128. The seal assembly 200 can be positioned between two adjacent rotor disks 136 that form the first component 702 and the second component 704, respectively. In this arrangement, the seal assembly 200 has a hollow cylindrical shape with respect to the central axis 112 and surrounds the rotor 134. The first surface 308 is an inner surface of the hollow cylinder and the second surface 310 is an outer surface of the hollow cylinder.

[0046] The seal assembly 200 can be a radial seal assembly that is positioned between two radially adjacent components. As illustrated in FIG. 9, the first component 702 is the vane platform 902 and the second component 704 is the carrier 906. The seal assembly 200 ispositioned between the vane platform 902 and the carrier 906. In this arrangement, the seal assembly 200 has a hollow cylindrical shape with respect to the central axis 112 and surrounds the rotor 134. The first side 312 is an inner surface of the hollow cylinder and the second side 314 is an outer surface the hollow cylinder. The shiplap between two adjacent seal segments 202 is the same as the axial seal assembly 200 illustrated in FIG. 2 to FIG. 8. It is also understood that the seal assemblies 200 can be used in other sections of the gas turbine engine 100, such as the compressor section 102, the combustion section 104, etc. It is also possible that the seal assembly 200 can be used in other type of engines, such as a steam turbine engine, a generator, or any devices that need seal assemblies.

[0047] During operation, components in the turbine section 106 are operated in a high temperature. The flow 716 may be a cooling flow that is introduced to the cold side for cooling the turbine components. The cold side has a pressure that is higher than a pressure of the hot side. The cooling flow 716 may enter the space 706 between the adjacent first component 702 and second component 704 and into the first slot 708 the second slot 710. The first wall 504 and the second wall 506 closes the gap 602 to reduce a leakage of the cooling flow 716 through the gap 602 from the cold high pressure region 714 to the hot low pressure region 712. The plurality of teeth 418 allows for smaller assembly tolerances which lead to a tighter fit of the seal assembly 200 in the first slot 708 and the second slot 710. The tighter fit improves the sealing performance. Reduction of the cooling flow 716 leakage improves efficiency of the gas turbine engine 100. The first chamfer 410, the second chamfer 412, the third chamfer 414, and the fourth chamfer 416 improve an assembly of the seal assembly 200. The hook 324 is inserted into the cutout 802 to inhibit a rotation of the seal assembly 200 during operation.

[0048] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0049] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be includedin the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.LISTING OF DRAWING ELEMENTS100 gas turbine engine102 compressor section104 combustion section106 turbine section108 inlet section110 exhaust portion112 central axis114 compressor stage116 stationary compressor vane118 rotating compressor blade120 combustor122 exhaust gas124 turbine stage126 stationary turbine vane128 rotating turbine blade130 turbine inletcontrol system rotor rotor disk seal assembly seal segment main body first end second end first surface second surface first side second side tongue first outmost end groove second outmost end hook first surface second surface first sidesecond side first chamfer second chamfer third chamfer fourth chamfer teeth base plate first wall second wall fillet gap first component second component space first slot second slot low pressure region high pressure region flow cutoutportion vane platform ring segment carrier

Claims

CLAIMSWhat is claimed is:

1. A seal assembly comprising: a plurality of seal segments, each seal segment of the plurality of seal segments comprising: a main body having a first end and a second end; a tongue extending from the first end to a first outmost end; and a groove extending from the second end to a second outmost end, the groove having a base plate, a first wall, and a second wall, the tongue of an adjacent seal segment inserted into the groove and positioned between the first wall and the second wall.

2. The seal assembly of claim 1, wherein the tongue has a thickness that is less than a thickness of the main body.

3. The seal assembly of claim 1, wherein the base plate has a thickness that is less than a thickness of the main body.

4. The seal assembly of claim 1, wherein the tongue comprises a first chamfer formed at a first edge between a first side of the tongue and the first outmost end and a second chamfer formed at a second edge between a second side of the tongue and the first outmost end.

5. The seal assembly of claim 1, wherein the tongue comprises a third chamfer formed at a third edge between a first surface and the first outmost end and a fourth chamfer formed at a fourth edge between a second surface of the tongue and the first outmost end.

6. The seal assembly of claim 1, wherein the first wall and the second wall are perpendicular to the base plate.

7. The seal assembly of claim 1, further comprising a hook formed at the second outmost end.

8. The seal assembly of claim 7, wherein the hook is perpendicular to the base plate.

9. The seal assembly of claim 7, wherein the hook has a width that is less than a width of the main body.

10. The seal assembly of claim 1, further comprising a plurality of teeth extending from the first end to the second outmost end.

11. An engine comprising: a first component having a first slot and a cutout; a second component adjacent to the first component, the second component having a second slot facing to the first slot; and a seal assembly positioned between the first component and the second component and inserted into the first slot and the second slot, the seal assembly comprising a plurality of seal segments, each seal segment of the plurality of seal segments comprising: a main body having a first end and a second end; a tongue extending from the first end to a first outmost end; a groove extending from the second end to a second outmost end, the groove comprising a base plate, a first wall inserted into the first slot, and a second wall inserted into the second slot, the tongue of an adjacent seal segment inserted into the groove and positioned between the first wall and the second wall; and a hook formed at the second outmost end and positioned into the cutout.

12. The engine of claim 11, wherein the tongue has a thickness that is less than a thickness of the main body.

13. The engine of claim 11, wherein the base plate has a thickness that is less than a thickness of the main body.

14. The engine of claim 11, wherein the tongue comprises a first chamfer formed at a first edge between a first side of the tongue and the first outmost end and a second chamfer formed at a second edge between a second side of the tongue and the first outmost end.

15. The engine of claim 11, wherein the tongue comprises a third chamfer formed at a third edge between a first surface and the first outmost end and a fourth chamfer formed at a fourth edge between a second surface of the tongue and the first outmost end.

16. The engine of claim 11, wherein the first wall and the second wall are perpendicular to the base plate.

17. The engine of claim 11, wherein the hook is perpendicular to the base plate.

18. The engine of claim 11, wherein the hook has a width that is less than a width of the main body.

19. The engine of claim 11, further comprising a plurality of teeth extending from the first end to the second outmost end.

20. The engine of claim 11, wherein the first component is one of a plurality of first components, and wherein the cutout is formed at a side facing to an adjacent first component.

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