FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Push Pull Axial Feed Mechanism"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: Larsen & Toubro Limited
L&T House, Ballard Estate, MUMBAI-400001, Maharashtra State, INDIA
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Push Pull Axial Feed Mechanism
Field of invention
The present invention relates to a push pull axial feed mechanism, and more specifically, to an axial feed drive for orientation of a telescopic tube assembly by means of a chain actuated by a screw drive and the storage mechanism for the chain.
Background of the invention
Generally, an axial feed drive (herein after referred as the "axial feed mechanism") is used for handling inspection tool thereon. The inspection tool is used to monitor health of a pressure tube subjected to internal pressure. The inspection tool has various sensing units with analog outputs. The inspection tool is also equipped with certain sample collecting unit requiring some hydraulic supply. Specifically, the inspection tool generates signals and passes the generated signals to a processing station with a cable, thereby adding a constraint of providing a hollow actuator to an axial feed mechanism. Further, there is also a constraint on the outer diameter of the actuator, which is required to be smaller than the pipe's inner diameter. A variety of axial feed mechanisms are available in the art. For example, a European Patent US 5927690 by James White, Nicholas Dragomir and James Stottsberry discloses an axial feed mechanism. However, the mechanism disclosed in the aforementioned patent is effective when there are no constraints on bending radius because of any members running through the push pull chain. Further, most of the conventional mechanisms have large closed length space, lower axial force generation capacity, higher mass of system and larger outer diameter for providing very large stroke.

Accordingly, there exist a need for a axial push pull feed mechanism having compact space envelope, high axial force requirement throughout the stroke range and which effectively lower system mass. Further, there also exist a need for the axial push pull feed mechanism, which is capable of being immersed into water during operation. Furthermore, there is a requirement of an axial feed for an inspection tool having large strokes and has maintaining modularity of various elements.
Object of the invention
An object of the present invention is to provide an axial feed mechanism having a flexible push-pull mechanism for handling an inspection tool thereon.
Another object of the present invention is to provide an axial feed mechanism capable of providing positive drive to an actuator and also capable of increasing mechanical advantage thereby reducing the power required for axial force generation thereof.
Yet another object of the present invention is to provide an axial feed mechanism, which is a compact for handling cable during pushing-pulling operation.
One more object of the present invention is provide an axial feed mechanism, which is capable of working in conjunction with a screw drive, thereby providing supply of chain and cable during the extension of the actuator, and collection of the chain and cable during retraction operation.

Still another object of the present invention is to provide an axial feed mechanism, which is capable of interfacing with an umbilical connector of the inspection tool for insertion and retrieval of the inspection tool.
Further object of the present invention is to provide an arrangement for rotation of the inspection tool at any intermediate stroke of the actuator keeping the cable to be endless and preventing the cable from twisting.
Summary of the invention
Accordingly, the present invention provides a push-pull axial feed mechanism for orienting and positioning of an inspection tool, the push pull axial feed mechanism comprising:
an inspection tool housing capable of accommodating an inspection tool therein, the inspection tool connected to a cable for transferring signals from the inspection tool to a processing station;
a axial feed telescopic assembly coupled to the inspection tool housing, the axial feed telescopic assembly having plurality of telescopic tubes capable of extending linearly;
a chain capable of actuating -an inspection tool and the axial feed telescopic assembly, the chain being flexible and hollow allowing the cable to pass therethrough;
a screw actuator having a screw drive with a gear train, the screw actuator capable of passing the chain therethrough for pushing and retracting the chain;
a link covering the chain assembly with a profile cut thereon for easy to assemble and disassemble, wherein the profile cuts interface with the screw actuator; and

a cable handling assembly capable of receiving the cable from the axial feed screw actuator through a idler sprocket, the cable handling assembly having a spiral profile, the cable handling assembly configured into two halves, the first spiral half being a fixed casing and a second spiral half being a movable casing, wherein the feed of the cable from first spiral half into the second spiral half and vice versa is displacement between the two halves of the cable handling assembly and the number of spirals in the cable handling assembly.
Typically, wherein the chain has profile cuts thereon for interfacing with links.
Typically, wherein the chain is interfaced with an innermost tube of the plurality of telescopic tubes in end other than the inspection tool side.
Typically, wherein the screw actuator interfaces with links through a screw drive shaft.
Typically, wherein the cable handling assembly is housed on rails and guides.
Typically, wherein the cable handling assembly is actuated by the screw actuator based on the feed of the inspection tool.
Brief description of drawings
Figure 1 shows a perspective view of a push pull axial feeding mechanism in accordance with the present invention;
Figure 2 shows a partial section view of a cable handling system, of the push pull axial feeding mechanism of figure 1;

Figure 3 shows a perspective view of a chain assembly and interface with the cable of the push pull axial feeding mechanism of figure 1;
Figure 4 shows a side view of a chain assembly of figure 3;
Figure 5 shows a perspective view of a sprocket of the push pull axial feeding mechanism of figure 1;
Figure 6 shows a side view of the axial feed actuator of the push pull axial feeding mechanism of figure 1;
Figure 7 shows a perspective view of axial feed actuator of figure 6;
Figure 8 shows a perspective view of the coupling of the axial feed telescopic assembly and the inspection housing of the push pull axial feeding mechanism of figure 1;
Figure 9 shows an exploded view of the axial feed telescopic assembly and the inspection housing of the push pull axial feeding mechanism of figure 1; and
Figure 10 shows an exploded view of the coupling of the axial feed telescopic assembly and the inspection housing of the push pull axial feeding mechanism of figure 1;
Figure 11 shows a sectional perspective view of guide bush on the portion of the telescopic tube assembly, of the push pull axial feeding mechanism of figure 1;

Figure 12 shows sectional side views of the part of the telescopic tube assembly, of the push pull axial feeding mechanism of figure 1;
Figure 13 shows a sectional perspective, view of the telescopic tube assembly, of the push pull axial feeding mechanism of figure 1; and
Figure 14 shows a sectional front view of the cable handling assembly, of the push pull axial feeding mechanism of figure 1.
Detailed description of the invention
The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.
The present invention provides a push pull axial feed mechanism for orienting and positioning an inspection tool and also capable of handling an inspection tool in axial direction with assistance of a telescopic tube assembly. Further, the push pull axial feed mechanism is capable of providing positive drive to an actuator and also increase the mechanical advantage thereby reducing the power required for axial force generation. Furthermore, the axial feed mechanism includes a compact cable handling system for handling cable during pushing-pulling operation.
The present invention is illustrated with reference to the accompanying drawings, throughout which reference numerals indicate corresponding parts in the various figures. These reference numerals are shown in bracket in the following description.

Referring now to figures 1-14, there are shown various views of an axial feed mechanism for orienting and positioning an inspection tool in accordance with the present invention. Specifically, the figure 1 shows perspective view of the axial feed mechanism (100) (hereinafter the mechanism (100)). The mechanism (100) includes a telescopic tube assembly (10), a screw actuator (20), a connector handling system (30), a flexible chain assembly (40), an idler sprocket (50), an inspection tool housing (60), and a cable handling system (70).
The telescopic tube assembly (10) includes a set of telescopic tubes (11a -f) accommodated in telescopic tube housing (10a) for providing axial displacement as well as rotation thereof. Specifically, each of the telescopic tubes of the set of the telescopic tubes is in interfaced with other telescopic tube by a sliding joint. The telescopic tube assembly (10) comprises of a telescopic tubes cylindrical body with three key slots cut at 120 degree on the outer diameter, while the outer cylinder has a corresponding male key to facilitate relative axial sliding and transmit rotation between tubes and the inspection tool (62) therethrough. Since the above cylinders are subjected to long strokes, there are also provided with supporting ring (76 a - e) to guide the tip of the telescopes for reducing the bending stress coming onto the telescopic tubes. Specifically, the telescopic tube housing (10a) is capable of housing number of cylinders also called telescopic tubes (1 la-f) is function of the stroke required by the mechanism (100) and the internal diameter of the aforesaid pressure tube. The telescopic tube assembly (10) is also capable of extending linearly and having sealing (10b) between each stage to protect the leakage of fluid from the external environment as shown in figure 9, 10 and 11.
The telescopic tube assembly (10) is connected to the inspection tool housing (60) by a quick-assembly-disassembly coupling (18). The inspection tool housing (60) houses an inspection tool (62), with the help of a connector handling system (30)

which is detachable when connection is established. The inspection tool (62) has a self centering mechanism (not shown & numbered) and a male connector (14) with the connector handling system (30).
Further, the inspection tool (62) is connected with the telescopic tube assembly (10) by a coupling mechanism (12) as shown in figure 9 and 10. The coupling mechanism includes a male connector (14) on the inspection tool (62) interfaced to a female connector (14a) via a connector coupler (16). The female connector (14a) is interfaced to the first stage tube (1 1f) of the telescopic tube assembly (10) via an interface adaptor (14b). Specifically, a compliant joint (not shown and numbered) is provided, which interfaces the inspection tool (62) with the interface adaptor(14)s A mechanical merntrer(19) is provided to assist in load transfer from the inspection tool (62) to the telescopic tube assembly (10) without loading the connector. The connector assembly (30) has been provided with the necessary sealing and dowel locations for easy connection.
Further, the mechanism (100) includes a connector handling system (30) for interfacing with the connector coupler (16) to couple and decouple the connector assembly (30). The connector coupler (16) is provided with teeth serrations (16a), wherein the corresponding teeth profile interfaces as shown in figure 8 and 10. The connector handling system can be removed after the aforesaid connection is established, and can be brought in when connection needs to be decoupled for several times. This way different types of tool with the interface similar to the inspection tool (62) can be used.
Referring back to figure 1, the inspection tool (62) and axial feed telescopic assembly (10) is actuated by a mono-articulated flexible chain assembly (40) (hereinafter the 'chain assembly (40)'). The chain assembly (40) is essentially

hollow having various profile cuts to ensure modular interface between other links. The chain assembly (40) is made hollow with a bore diameter having slight clearance as compared to a cable (44) coming from the inspection tool (62) as shown in figure 3.
The chain assembly (40) is interfaced with a second stage tube (not numbered) of the axial feed telescopic assembly (10). A first stage tube (10a) as shown in figure 12, of the axial feed telescopic assembly (10) allows the cable (44) to be passed without outer sheathing cover of the cable to provide necessary compliance for the cables to twist during the inspection tool (62) rotation operation. Specifically, the links are designed in such a way that enables the chain (40) to have bending in only one direction, and remain taut when made straight. Further, the links also have a provision, which enables mechanical restriction of the chain (40) from bending in one direction to safeguard the cable (44) from reaching its minimum bending radius.
The chain (40) assist in providing long strokes and modularity required thereof. The chain (40) is flexible in one direction, so as to allow the free passage of the cable (44) and also arrest the bending of cable (44) from reaching its minimum bending radius. The chain (40) is composed of a hollow cylinder with geometrical profiles provided to attain both push pull requirement of the telescopic tube assembly (10). The chain pivoting position is provided with necessary arrangement to prevent disassembly of the chain (40) due to lateral sliding between links.
Specifically, the chain assembly (40) passes through the screw actuator (20) having a screw drive (22) through a gear train (24) as shown in figure 7. The screw actuator (20) interfaces with the chain (40) through a slot cut at the helix angle of a screw drive shaft (20a). The interfacing of the screw actuator (20) interfaces with the

chain (40) and provides a positive interface between the screw and the chain (40) thereby ability to control exact position of the screw actuator (20). The length of the cable (44) and the chain (40) function of the stroke required by the mechanism (100).
Referring now to shown in figures 3 and 4, links of the chain assembly (40) are interfaced with each other on arresting surfaces. Specifically, the two links, for example, a link (42a) and a link (42b) are hollow to allow the accommodation of the cable (44) thereby making a single assembled unit of the flexible chain assembly (40). More specifically, the first arresting surface (46) helps transfer of load when the chain assembly (40) is horizontal, while the second arresting surface (48) helps in restricting the cable (44) and chain assembly (40) from achieving an effective bending radius lesser than the bending radius of the cable. Further, a groove (49) on each link of the chain assembly (40) is provided for interfacing with the screw actuator (20) for actuation of the chain assembly (40). The groove (49) is cut into a helix to obtain interfacing with the screw in turn attaining a worm and worm wheel like arrangement. The chain pivoting faces(48a,48b) is provided with necessary arrangement allows oscillatory motion between the links (42a,42b) while preventing lateral sliding between links, thus preventing disassembly of the chain (40) and maintaining predefined clearance between the cable(44) and chain (40).
The additional cable and chain assembly is stored in the cable handling system (70), which is positioned in a plane in which the chain assembly (40) is bending. The chain assembly (40) is fed to the cable handling system (70) via the idler sprocket (50), which guides the chain assembly (40) towards the cable handling system (70).
Specifically, the cable handling system (70) includes a fixed casing (72) and movable casing (74) mechanism as shown in figure 1 and 2. The cable handling

system (70) accommodates longer lengths of the chain assembly (40) for retrieving the required length of cable (44) and chain assembly (40) in synchronization to the stroke requirement of the cable (44). The cable handling system (70) is a spiral guide with the innermost curve derived from the minimum bending radius of the chain assembly (40). More specifically, the cable handling system (70) is a spiral disc cut into two halves and positioned away from each other. The feed of the cable from and into the cable handling system (70) is essentially the displacement between the two halves (72 and 74) of the spiral disc and the number of spirals in the disc.
The cable handling system (70) is housed on a set of LM rails and guides and is actuated by a separate linear actuator (different from screw drive (20)) whose motion is synchronized with that of screw drive (20) based on the feed of the inspection tool (62). The cable handling system (70) enables to eliminate the requirement of a rotary cable junction, which is typically required while using conventional winching systems. This provides the necessary interface requirement of the cable to be stored and handles without any break in the cable in contrast to the one generally provided in conventional winching system.
The total stroke of the cable handling system (70) compensates to the total movement of the inspection tool (62) and is a function of the stroke between the fixed casing (72) and the movable casing (74). Further, the cable handling system (70) is also provided with a guiding element to reduce the friction between the links of the chain assembly (20) and the fixed and movable casing (72 & 74). Furthermore, the guiding element (76) can be metallic guide rings as shown in figure. Alternatively, balls andVor rolling elements can be used as the guiding elements instead. The guiding element (76) are provided at a predefined configuration (as shown in figure 2, 14) to reduce the coefficient of friction with

between the chain assembly (40) and the fixed and movable casing (72 & 74). Since the chain assembly (40) is to cater to some bending radius in the fixed and movable casing (72 & 74), to reduce sharp edges produced due to bending of relative links with each other, the guiding element (76) are specifically located in places where there is no projections thereby reducing the relative wear and tear of the links of the chain assembly. Thus, if the link assembly is guided along the periphery as done in conventional bearings, the sharp edges will wear out the system.
As shown in figure 6 and 7, a screw drive (20a) of the axial feed screw actuator (20) for axial feed of the chain assembly includes a set of gear units (22) for transmission of power to the screw drive (20a). The screw drive (20a) is interfaced with the links of the chain assembly (40) via the grooves. For example, the screw drive (20) interfaces with the link (42) of the chain assembly (40) via the groove (49). As the screw drive (20a) rotates, the chain assembly (40) is pushed forward or retracted depending on the direction of rotation.
Further, the mechanism (100) includes a hollow casing (24) of the cable handling assembly (70) for supporting the chain assembly (40) to ensure contact between the links of the chain assembly (40) and the screw drive (20a). The screw drive (20a) is supported on a bracket (26), which is also used to house the idler sprocket (50).
The idler sprocket (50) ensures proper bending radius to the cable (44) and chain assembly (40). As shown in figure 5 and 6, the idler sprocket includes of a specified geometry for idler sprocket to the link interface and a second groove (52) for retaining the cable and chain assembly (40). The second groove (52) ensures that the cable (44) and the chain assembly (40) remain in the center of the idler sprocket (50) at all times.

Further, the mechanism (100) includes a rotary actuator (80) capable of rotating the telescopic tube assembly (10) to a constrained rotation degree of freedom as shown in figure 12. In an embodiment, the cable includes coaxial cables, stainless steel strands and hydraulic hoses, covered by suitable sheet of PVC to provide protection to the individual cable. The cables coming out of the female connector (14a) are kept loose (without cover sheathing (44a)) till the end of the first telescopic tube (10a). After the first stage, the cables are then bound together with a common sheathing (44b) as shown in 13. The open sheathed cables in the first stage tube are twisted and coiled'inside so as to provide flexibility to the cables to cater to limited twisting so as to provide rotational degree of freedom to the inspection tool (62) without having any break in the cable (44).
The mechanism (100) may be used in any pipe inspection system, such as long stroke electrically actuated linear actuator without screw and self locking property, bore well digging, which requires axial and rotary motion, elevators mechanisms, axial feed mechanisms required to be used under water without exposing the push pull chain and the mechanism into water, pipe cleaning equipment and the like where compactness and high capacity are critical requirements.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of

equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. A push-pull axial feed mechanism for orienting and positioning of an inspection tool, the push pull axial feed mechanism comprising:
an inspection tool housing capable of accommodating an inspection tool therein, the inspection tool connected to a cable for transferring signals from the inspection tool to a processing station;
a axial feed telescopic assembly coupled to the inspection tool housing, the axial feed telescopic assembly having plurality of telescopic tubes capable of extending linearly;
a chain capable of actuating an inspection tool and the axial feed telescopic assembly, the chain being flexible and hollow allowing the cable to pass therethrough;
a screw actuator having a screw drive with a gear train, the screw actuator capable of passing the chain therethrough for pushing and retracting the chain;
a link covering the chain assembly with a profile cut thereon for easy to assemble and disassemble, wherein the profile cuts interface with the screw actuator; and
a cable handling assembly capable of receiving the cable & chain assembly from the axial feed screw actuator through a idler sprocket, the cable handling assembly having a spiral profile, the cable handling assembly configured into two halves, the first spiral half being a fixed casing and a second spiral half being a movable casing, wherein the feed of the cable from first spiral half into the second spiral half and vice versa is displacement between the two halves of the cable handling assembly and the number of spirals in the cable handling assembly.

2. The push-pull axial feed mechanism of claim 1, wherein the chain has profile cuts thereon for interfacing with links.
3. The push-pull axial feed mechanism of claim 1, wherein the chain is interfaced with an innermost tube of the plurality of telescopic tubes in end other than the inspection tool side.
4. The push-pull axial feed mechanism of claim 1, wherein the screw actuator interfaces with links through a screw drive shaft.
5. The push-pull axial feed mechanism of claim 1, wherein the cable handling assembly is housed on rails and guides.
6. The push-pull axial feed mechanism of claim 1, wherein the cable handling assembly is actuated by the screw actuator based on the feed of the inspection tool.