WO2013104589A1

WO2013104589A1 - Tie rod kit system

Info

Publication number: WO2013104589A1
Application number: PCT/EP2013/050164
Authority: WO
Inventors: Matthias Müller
Original assignee: Jet Aviation Ag
Priority date: 2012-01-09
Filing date: 2013-01-07
Publication date: 2013-07-18
Also published as: EP2802784A1

Abstract

The invention is directed to a tie rod kit system comprising at least two rods each having a specific length. At least one tie rod head is adjustable in length whereby the adjustable length of the tie rod head corresponds to the length difference between two rods.

Description

TIE ROD KIT SYSTEM

FI ELD OF TH E I NVENTION

The invention is directed to a tie rod system according to the preamble of the independent claims.

DESCRI PTION OF RELATED ART

DE20201 0000321 was published on 24.06.201 0 on behalf of RO RA PRODU KTIONS GM BH describes a tie rod, partly made out of CFRP, with a ratched mechanism and which has two coupling elements that allow for a variation in length by using thread arrangements. The thread arrangement allows a limited variation of the tie rod length. Sealing elements between the coupling element and the connecting pieces prevent intrusion of pollution and leakage of lubricant.

WO06042750 was published on 27.04.2006 on behalf of G MT Gummi Metall Technik GmbH . It describes a tie rod with at least one coupling element that can be used to adjust the tie rod length during installation, even when spatial accessibility is limited. At least one of the two coupling elements is connected to the centerpiece by a thread so that the tie rod length can be changed by screwing the coupling element in or out. In addition, an apparatus is described which can be used to fix the coupling agent in order to prevent further relative rotations between coupling element and centerpiece and thus also changes in tie rod length. This fixation device consists of a clamp that is mounted on the coupling element using a bolt and which embraces and a part of the centerpiece that is shaped like a gearwheel. By form closure relative rotations are inhibited. The tie rod also includes a spring element which is used to preload the thread in order to reduce vibration/noise when in service. The presence of this spring element also limits how much the length of the tie rod can be changed.

DE202004004407U was published on 22.07.2004 on behalf of Trigum Engineering GmbH and claims a tie rod which in many details conforms to the one presented in WO06042750. A restraint element on the coupling element prevents the threaded coupling element from being screwed out too much. In contrast to WO06042750, the presented tie rod does not include any spring element. The clamping element used to prevent rotations is mounted using the same bolt that will be used to connect the tie rod to the aircraft.

DE202009008388U was published on 08. 1 0.2009 on behalf of GMT Gummi Metall Technik GmbH and describes a tie rod with a thread that is free from float due to using different pitches for corresponding inner and outer threads. This becomes feasible due to using different materials for the outer (metal) and inner ( plastic) thread. A restraint ele- ment is used to prevent excessive extension.

W01 0024990 was published on 04.03.201 0 on behalf of The Boeing Company and claims a composite tie rod and a method for producing it. The composite tie rod comprises an open lattice body formed of interlaced filaments held in a solid matrix. A pair of fittings is rigidly connected to the rod ends with the ends of the body. The rod ends form attachment points on the tie rod. Adjustability of the length of the tie rod is not foreseen. SU M MARY OF TH E I NVENTION

One object of the present invention is to provide a tie rod, respectively a tie rod kit system with an improved adjustability and load carrying capability.

Tie rods are an important component used in aircraft construction. Serving as connectors in order to anchorage points on the structural components of the aircraft's hull, they are in the field of VI P aircraft completion commonly used for the installation of cabin compartments and other modules. Customized tie rods are obtainable on order from multiple manufacturers. Their length is predefined and related to the specific application. Furthermore these products allow only for a slight adjustment of the length of the tie rod. Hence the adjustment range of current tie rods used in aircraft construction is fairly limited and results in the problem that e.g. when a modification is required the custom made tie rods need to be replaced by new tie rods. Especially in the manufacturing in VI P aircraft interiors changes in the design and the arrangement of the interior are during the construction of the aircraft quite common. As the commonly known tie rods can not be reused and therefore must be replaced when a change becomes necessary tie rods which are based on the commonly known tie rods are very expensive. A further major advantage is the significant reduction of lead time.

The novel concept of the present invention not only allows the reduction of parts necessary but also offers the advantage of easy adjustment of the tie rods within a larger range of tie rod length whereby the load capacity is not negatively affected when adjusting the length of the tie rod. One aspect of the invention is directed to a tie rod kit system ( kit) to assemble tie rods. The kit comprises at least two rods each having a specific length. The length difference between the two rods is e.g. 50 mm or 1 00 mm and normally corre- sponds to the maximum adjustability of one tie rod head according to the present invention or a combination of two tie rod heads according to the present invention.

In an embodiment a tie rod head according to the present invention has a special design which offers the advantage of high load capacity, an extended range of adjustability and a low weight. By the special design of the tie rod head according to the present invention the ratio between the load capacity and the available working length is optimized. The kit system is based on a modular setup whereby each tie rod comprises at least one adjustable tie rod head. Each adjustable tie rod head comprises means for load application, e.g. a ball head or a lug and an outer surface having a specific diameter which comprises a thread having a specific length. The specific length of the thread is adapted to the length differences between the at least two rods of the tie rod kit system.

In an embodiment the extended adjustability of a tie rod head is achieved by one or more shaft elements each having a specific design and length. Thereby it becomes possible to reduce the extended thread length by using at least one of the shaft elements to adjust the effective length of the thread, respectively the tie rod. A shaft element normally comprises on one side an external thread, or another fixation means, by which it can be interconnected to a rod or another intermediate element. On the other end the intermediate element normally comprises an internal thread, or another fixation means, by which it can be interconnected to a load application means such as a ball head. The length can be adjusted by the combination of one or more intermediate elements.

The rods of the tie rod kit system may have different load capacity with respect to compression. This can be achieved e.g. by the choice of the material, the design of the cross- section (such as wall thickness and/or diameter) or a combination thereof. The kit preferably comprises several rods which are designed to a specific load capacity. The rods can be made out of a metal alloy or a fibre reinforced material, e.g. carbon fibers, Kevlar® fibers, or a combination thereof. The wall thickness may be variable in length direction . Very good results may be achieved in that the fibers are embedded in a duroplastic or a thermoplastic matrix material, such as PEEK. The advantage of a thermoplastic material is the improved reduction of vibrations and noise.

One aspect of the invention is directed to a tie rod kit system comprising at least two rods each having a specific length and at least one tie rod head with an adjustable length. The adjustable length of the tie rod head corresponds to the length difference between the at least two rods. In a preferred embodiment the length adjustability between two adjacent rods may have an overlap such that a specific length can be covered by two different tie rod assemblies. Good results are achieved by an overlap of 1 0mm to 20mm. The tie rod kit system may comprise several tie rod heads comprising different load application means. A tie rod head may comprise a shaft with an outer surface which comprises a thread with a specific length. The specific length of the thread is adjusted to the difference of the length between the at least two rods. The physical length reduction resulting from a bushing screwed onto the thread has to be considered when calculating the length available for adjustment of the length of the rod head. The ratio between the adjustable free length of the first thread and the thread diameter preferably is in the range of 2 to 8 or 3 to 1 0. The shaft may be at least partially designed as a bushing comprising an inner diameter ( bore) . The bushing may have a minimal wall thickness providing sufficient load capacity. This has a positive effect to the overall weight. The wall thickness may ( measured from the inner dia meter of the thread ) be in the range of 2mm to 4mm. Depending on the field of application other wall thickness may appropriate. The inner diameter of the bore may be in the range of 1 0 mm to 50 mm. In a preferred embodiment the wall of the inner diameter is ( in a section view) adjacent to the first thread. Stop elements which are in a radial direction of the sectional view arranged in-between have a negative effect on the wall thickness and the overall weight. The shaft element of the tie rod head may have on one end a connecting means suitable to receive a standardized load application means, e.g. in the form of a ball head. In a preferred embodiment a rod is made out of a composite material, e.g. such as carbon fibers or glass fibers or Kevlar® or a mixture thereof. A bushing suitable to interconnect the tie rod head to a shaft may be directly incorporated in a tube of the rod. Especially when the tube of the rod is made out of an isolating material the rod ends, respectively the tie rod heads may be electrical interconnection each other. Normally the at least two rods ( made out of the same rod material) of a tie rod kit system are having different cross-sections wherein, the cross- section of the longer rod preferably has a larger surface then the cross-section of the shorter rod. If appropriate one tie rod head has a fixed length. If appropriate one tie rod head is interconnected to the rod by rivets and or glue. To bridge a distance between 200 mm and 2000 mm a kit according to the present invention e.g. comprises eighteen rods each having a different length of about 1 00 mm, i.e. the first rod has a length which in combination with two tie rod heads according to the present invention corresponds to 200 mm.

In a further embodiment the tie rod kit system covers a tie rod length in the range of 500 mm to 2000 mm in a way that there is at least one combination comprising two or three standard adapters (shaft elements) with different length and a standard rod end, e.g. M EK5. Thereby it is possible to avoid a customized extended thread to create any length in that range. In this embodiment compression elements are having lengths between 30 mm and 80 mm as well as several rods having different lengths with 1 00 mm increments. The rods are preferably made out of fibre reinforces plastic material and/or a metal alloy. Very good results are achieved with carbon fibre reinforced material. In this embodiment the kit may e.g. consist of 1 6 rods from 400mm to 1 900mm ( 5x25 mm; 1 1 x40 mm ) as well the required steel compression elements. Using a standard rod end as available on the marked (e.g. M EK- Rod end of the company called Heim or any other) may have a positive effect regarding the manufacturing cost.

In a further embodiment a kit system comprises several standard rods made out of aluminum having a tie rod length range of in the range of e.g. 250 mm to 850 mm. If appro- priate an existing ratching-type of rod end as e.g. known from a company called Ro- Ra GmbH can be used on one end of the tie rod.

Rods which are made out of fibre reinforced material may comprise on each end an insert e.g. made out of metal or any other suitable material. The inserts are clued and/or riveted to the fibre reinforced material, e.g. carbon fibers embedded in a matrix material. In an advantageous embodiment the metal inserts are electrically interconnected to each other e.g. by a wire or a wire mesh made out of a conductive material attached to one of the surfaces of the rod or at least partially embedded in matrix material. Furthermore the inserts are electrically interconnected directly or indirectly, e.g. via at least one tie rod heat, to the structure of the airplane. The electric interconnection can be used for equipotential bonding.

In an embodiment the tie rod heads on each end of a tie rod are the same, i.e. both tie rod heads are adjustable in their length. Due to the fact that the pitch and the rotation of the thread is the same, a relative rotation of the rod with respect to the tie rod heads does not affect the length. This is advantageous for safety reason, e.g. when a locking element should not be engaged, the length of the tie rod can not be modified. For adjustment of the length a relative rotation of the rod ends with respect to each other is necessary, i.e. only by removing one of the attachment fitting this will be possible.

A tie rod head according to the present invention comprises in one embodiment a shaft with an outer surface with a thread suitable to be connected with rods having different lengths. The shaft has an inner bore extending in the direction of the load application means. The side wall of the inner bore may be at least partially cylindrical, or conical, or has a diameter which is reduced in steps. The tie rod head may be made in a multi-part form comprising a shaft element with a fastening means to which a standard rod end is attached. The length of the bore in the shaft may be shorter, equal or longer then the length of the th read. The tie rod head is preferably made out of a metal alloy, e.g. steel, titanium or aluminum.

BRI EF DESCRPTION OF TH E DRAWI NGS

Fig. 1 shows a tie rod kit system in a perspective manner;

Fig. 2 shows detail A according to Figure 1 ;

Fig. 3 shows the tie rod end according to Figures 1 and 2 in a perspective view;

Fig. 4 shows a front view of a tie rod head attached to a rod end;

Fig. 5 shows the a section view through the rod according to Figure 4;

Fig. 6 shows a second embodiment of a tie rod head in a front view;

Fig. 7 shows a section view of the tie rod end according to Figure 6;

Fig. 8 shows a further embodiment of the present invention. DETAI LED DESCRI PTION OF TH E I NVENTION

The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purposes of illustrating the invention, an embodiment that is presently preferred, in which like n umerals represent similar parts throughout the several views of the drawings, it being understood, however, that the invention is not limited to the specific methods and instrumentalities disclosed.

Figure 1 shows a tie rod kit system 1 in a perspective view. Figure 2 shows detail A of Figure 1 . The tie rod kit system 1 comprises several rods 2. 1 , 2.2 each having a different length L 1 , L2. In Figure 1 only two assembled rods 6 are shown. However a complete tie rod kit system 1 may comprise 1 0-20 individual rods 2. 1 , 2.2 having individual length and/or load carrying capacity. Each rod 2. 1 , 2.2 is having a first and a second end 3 , 4 to each of which a tie rod head 5 is attached. In the shown embodiment the rod heads 5 are the same. Depending on the filed of application other embodiments are possible, e.g. with only one adjustable rod head 5.

In Figure 1 a first and a second assembled tie rod 6 are visible each having an adjustable length due to the adjustable first and the second tie rod head 5. Due to the extended adjustability of the tie rod heads in length direction it is possible to bridge the difference between the first and the second length L1 , L2 of the first and the second rod 2. 1 , 2.2 and achieve the same total length between a first and a second load application means 9 of each tie rod head. In the shown embodiment the diameter D 1 of the shorter rod 2. 1 is smaller than the diameter D2 of the longer rod 2.2 resulting in a smaller cross section, respectively in a smaller moment of inertia. However the load capacity with respect to compression load may be adjusted to remain the same due to the reduced length. Thereby it is possible to achieve a minimum weight necessary. With respect to compression load a further possibility to take influence would be to use a material with a different E-Modulus. By extending the length of the shaft 1 0 and the thread 1 1 a certain overlap can be achieved, i.e. both rods can be used for the same length. In the shown embodiment the load application means are in the form of ball heads 9. However tie rod heads may be designed with other load application means such as e.g. a clevis or any other suitable attachment means. As it can be best seen in Figure 2 the first thread 1 1 of the shown embodiment is in a mounted position engaged with a second thread 1 3 of the rod end 3 ( respectively rod end 4) .

Figure 3 shows the adjustable rod head 5 according to Figures 1 and 2 in an isolated manner in a perspective view. The rod head 5 is shown in a partially cut manner such that the interior is visible. The rod head 5 comprises a load application means 9, here in the form of a ball head 9. The load application means 9 is interconnected to a shaft 1 0. The shaft 1 0 comprises a first outer thread 1 1 with a specific thread length Lt and a specific thread diameter Dt. On the thread 1 1 , respectively on the shaft 1 0 a bushing 1 2 is arranged. The bushing 1 2 comprises a second inner thread 1 3 which interacts in a mounted position with the first outer thread 1 1 . The bushing 1 2 has a third outer thread 1 4 by which the bushing 1 2 can be attached to the first or the second end 3 , 4 of a rod 2 (see Figure 1 ). Depending on the field of application the bushing 1 2 can be part of or be integrated into an end of a rod 2. 1 , 2.2 (see Figures 4 and 5 ). As it can be seen in Figure 3 the shaft 1 0 of the shown embodiment is hollow with an interior diameter 1 5. A stop element 1 6 is arranged inside the interior diameter 1 5 and encompasses the rear end of the shaft 1 0. The stop element 1 6 comprises arms 1 7 which extend above the outer surface of the shaft 1 0, respectively the first outer thread 1 1 and interacts with the bushing 1 2 thereby preventing that the shaft 1 0 can be screwed to far out. This special arrangement of the stop element does not negatively affect the maximum diameter of the inte- rior diameter. If the stop element would be arranged on the outside a much higher wall thickness would be necessa ry which negatively affects the weight of the tie bar head 5. In the shown embodiment the interior diameter 1 5 has a uniform diameter over its complete length. Depending on the field of application the diameter can have a taper angle or be reduced in its size in one or several steps versus its closed end. Depending on the design of the load application element the inner diameter 1 5 can be open on both ends, whereby said opening may act as a venting hole. In front of the bushing 1 2 a locking nut 1 8 is arranged to lock the shaft 1 0 of the rod head 5 with respect to the bushing 1 2.

Figure 4 shows an assembled tie rod 6 in a front view. A rod head 5 is attached to an end of a rod 2. Figure 5 shows the assembled tie rod 6 in a section view along section line BB according to Figure 4. Regarding the general principle of the functionality it is referred to the description of the previous drawings. As it can be seen in the section view according to Figure 5, the busing 1 2 of the shown embodiment is integrated into the rod 2. A tube 8 of the rod 2 is made out of carbon reinforced material. The bushing 8 comprises a conical outer shape and is bonded to the inside of the tube 8. In the shown embodiment no stop element as shown in Figure 3 is present. If required a stop element can be incorporated. As it can be seen in Figure 5 the length Lb of the bore 1 5 in the shaft 1 0 is about the same as the length Lt of the thread 1 1 . Depending on the field of application the length of the shaft may be smaller or larger then the length Lt of the thread 1 1 .

Figure 6 shows a further embodiment of a rod head 5 in a front view and Figure 7 shows the rod head 5 in a section view along section line CC according to Figure 6. The rod head 5 comprises a shaft element 1 0 with an outer thread 1 1 . Also in this embodiment the shaft element 1 0 comprises an inner diameter ( bore) 1 5. The inner diameter is chosen such that it does not negatively affect the load carrying capacity of the rod head 5 but significantly reduces the overall weight. If appropriate a stop element e.g. as shown in Figure 3 can be incorporated. In difference to the other embodiments the load application means 9 is formed as a separate element which is interconnected to the shaft 1 0. The shaft element 1 0 comprises a fastening means here in the form of a bore 1 9 with an inner thread ( not shown in detail). The load application means of the shown embodiment is a standardized rod end, e.g. in the form of a ball head as commonly available on the marked. Although that the overall weight may be slightly increased, the advantage of the shown embodiment can be seen in the potential cost saving. A further advantage is that the load application element can be exchanged if necessary.

Figure 8 shows a tie rod kit system 1 according to the present invention. The tie rod kit system 1 comprises several rods 6 having different length. The rods 6 are shown partially. Therefore their full length and the opposite rod end are not visible. The rod ends 3 each comprise a shaft element 1 0 with different length L1 - L3. In Figure 8a the rod end is shown in a partially cut off manner such that the inside of the shaft element 1 0 and the rod 6 becomes visible. On the outer (distal) end of the shaft element 1 0 a standard load application means in the form of a ball head 9 is attached to the bore 1 9. On the opposite (dorsal) end the shaft element 1 0 comprises a disc like stop element 20 and a first thread 1 1 wh ich, in a mounted position, interacts with a second internal thread 1 3 of the bushing 1 2. The shaft elements 1 0 are e.g. having lengths between 30 mm and 80 mm as well as several rods having different lengths with 1 00 mm increments.

REFERENCE SIGNS

1 Tie rod kit system

2 Rod

a. 2.1 First rod

b. 2.2 Second rod

3 First rod end

4 Second rod end

5 Rod head

6 Tie rod

7 First assembled tie rod

8 Tube (rod 2)

9 Load application means (ball head, clevis)

10 Shaft (shaft element)

11 First outer thread (shaft)

12 Bushing

13 Second inner thread

14 Third outer thread

15 Inner diameter (bore in shaft)

16 Stop element

17 Arm (stop element)

18 Locking nut

19 Bore (shaft 10)

20 Disc like stop element

Claims

PATENT CLAIMS What is claimed is:

1 . A tie rod kit system comprising at least two rods each having a specific length and at least one tie rod head with an adjustable length whereby the adjustable length of the tie rod head corresponds to the length difference between the at least two rods.

2. The tie rod kit system according to claim 1 , wherein the tie rod kit system comprises several tie rod heads comprising different load application means.

3. The tie rod kit system according to claim 2, wherein a tie rod head comprises a shaft with an outer surface comprising a thread with a specific length whereby the specific length of the thread is adjusted to the difference of the length between the at least two rods.

4. The tie rod kit system according to claim 3 , wherein the ratio between the adjustable free length of the first thread and the thread diameter is in the range of 2 to 8.

5. The tie rod kit system according to claim 3 , wherein the shaft comprises an inner diameter which in a section view is arranged adjacent to the first thread.

6. The tie rod kit system according to claim 3 , wherein the tie rod head comprises a shaft, said shaft comprises on one end a connecting means suitable to receive a standardized rod end.

7. The tie rod kit system according to claim 6, wherein the shafts are having lengths in the range of 30mm to 80mm.

8. The tie rod kit system according to claim 7, wherein the tie rod kit system comprises shafts having different length

9. The tie rod kit system according to claim 1 , wherein the adjustment length corresponds to the length difference of the at least two rods plus an overlap.

1 0. The tie rod kit system according to claim 1 , wherein at least one rod is made out of a composite material.

1 1 . The tie rod kit system according to claim 1 0, wherein a bushing suitable to interconnect to a shaft is incorporated in a tube of the rod.

1 2. The tie rod kit system according to claim 1 0, wherein the at least one rod comprises an electrical interconnection electrically interconnecting the rod ends to each other.

1 3. The tie rod kit system according to claim 1 , wherein the at least two rods are having different cross-sections.

14. The tie rod kit system according to claim 1 0, wherein, the cross-section of the longer rod has a larger surface then the cross-section of the shorter rod.

1 5. The tie rod kit system according to claim 1 , wherein one tie rod head has a fixed length.

1 6. The tie rod kit system according to claim 1 5, wherein one tie rod head is interconnected to the rod by rivets and or glue.

1 7. Tie rod head comprising a shaft with an outer surface with a thread suitable to be connected with rods having different lengths, wherein the shaft has an inner bore extending in the direction of the load application means.

1 8. The rod head according to claim 1 7, wherein the side wall of the inner bore is at least partially cylindrical, or conical, or has a diameter which is reduced in steps.

1 9. The rod head according to claim 1 7, wherein the tie rod head comprises a shaft element with a fastening means to which a standard rod end is attached.

20. The rod head according to claim 1 7, wherein the length of the bore in the shaft is shorter then the length of the thread.

21 . The rod head according to claim 1 7, wherein the tie rod head is made out of steel, titanium, alumin um.