Disclosure of Invention
Therefore, the invention aims to provide the oil pipe passing packer with the corrugated and net-shaped composite steel skeleton, which has better sealing performance when in setting operation and unsetting operation, can realize smooth switching between the unsetting operation and the setting operation, ensures that the packer can be smoothly lifted out, and ensures the service life and the operation reliability and stability.
In order to achieve the above object, the present invention provides the following technical solutions:
a through tubing packer having a corrugated and mesh composite steel skeleton, comprising:
the framework mechanism comprises a second framework and first frameworks symmetrically arranged at two ends of the second framework;
the outer rubber cylinder is sleeved on the outer side of the second framework;
the inner rubber cylinder is arranged at the inner side of the framework mechanism and is internally provided with a circulation cavity;
The central tube is arranged on the inner side of the inner rubber cylinder, a hydraulic cavity is formed between the central tube and the inner rubber cylinder, a liquid through port is arranged on the central tube, and the liquid through port and the liquid through cavity are communicated with the hydraulic cavity;
the hoop protection mechanism is sleeved at the end part of the inner rubber cylinder and is connected with the first framework;
When the expansion liquid is injected into the circulation cavity, the inner rubber cylinder expands to extrude the framework mechanism to enable the outer rubber cylinder to be attached to the sleeve; when the expansion liquid is discharged from the circulation cavity, the inner rubber cylinder contracts to reset the framework mechanism.
Preferably, the first framework is a corrugated framework, the second framework is a net framework, and the corrugated angle of the corrugated framework is consistent with the corrugated angle of the net framework.
Preferably, the outer rubber cylinder comprises a second outer rubber cylinder and first outer rubber cylinders symmetrically arranged on two sides of the second outer rubber cylinder, and the height of the second outer rubber cylinder is larger than that of the first outer rubber cylinder.
Preferably, a limiting component is arranged in the hoop protection mechanism and used for limiting the relative offset between the central tube and the inner rubber cylinder.
Preferably, the limiting assembly comprises a pressing cap and a fixing ring connected with the pressing cap, the fixing ring is sleeved on the outer side of the central tube and connected with the inner rubber cylinder, and the pressing cap is sleeved on the end portion of the central tube.
Preferably, a plurality of clamping grooves are formed in the fixing ring, and sealing rings used for pressing the inner rubber cylinder are arranged in the clamping grooves.
Preferably, the inner rubber cylinder is connected with the hoop protection mechanism through a first fastener which is transversely arranged, and a back ring which is longitudinally arranged is further arranged between the fixing ring and the central tube.
Preferably, the device further comprises a pushing assembly, the pushing assembly comprising:
the pushing piece is arranged in the hydraulic cavity;
the piston ring is connected with the moving end of the pushing piece and can move up and down to push the expansion liquid;
And the driving piece is connected with the fixed end of the pushing piece.
Preferably, the skeleton mechanism and the inner rubber cylinder are vulcanized and formed, and the outer rubber cylinder and the second skeleton are vulcanized and formed.
Preferably, the hoop protection mechanism comprises a first hoop protection mechanism and a second hoop protection mechanism which are respectively arranged on two sides of the framework structure, the first hoop protection mechanism and the second hoop protection mechanism are respectively provided with a pressure sensor, and one side signal of the pressure sensor is connected with an amplifier.
The oil pipe passing packer with the corrugated and net-shaped composite steel skeleton comprises a skeleton mechanism, an outer rubber cylinder, an inner rubber cylinder, a central pipe and a hoop protection mechanism, wherein the skeleton mechanism comprises a second skeleton and first skeletons symmetrically arranged at two ends of the second skeleton; the outer rubber cylinder is sleeved on the outer side of the second framework, the inner rubber cylinder is arranged on the inner side of the framework mechanism and is internally provided with a circulation cavity, a central pipe is arranged on the inner side of the inner rubber cylinder, a hydraulic cavity is formed between the central pipe and the inner rubber pipe, a liquid through hole is formed in the central pipe, the liquid through hole and the circulation cavity are communicated with the hydraulic cavity, expansion liquid is fed into the circulation cavity of the inner rubber cylinder after passing through the liquid through hole and the hydraulic cavity, after entering the inner rubber cylinder, the inner rubber cylinder expands to extrude the framework mechanism, so that the first framework and the second framework expand simultaneously, the outer rubber cylinder expands to be attached with a sleeve, sealing and anchoring effects are achieved, and the setting operation of the packer is completed; after the sealing and anchoring operation is finished, the expansion liquid returns to the hydraulic cavity from the circulation cavity, and after the expansion liquid flows out of the liquid outlet, the inner rubber cylinder can retract, the framework mechanism resets, and the deblocking operation of the packer is finished; in addition, the inner rubber cylinder is sleeved with the hoop protection mechanism, and the hoop protection mechanism is connected with the first framework and is used for sealing the end surfaces of the first framework and the inner rubber cylinder, so that the tightness in the setting operation and the deblocking operation can be ensured; the oil pipe passing packer with the corrugated and net-shaped composite steel skeleton can realize smooth switching of deblocking operation and setting operation, ensure that the packer can be smoothly lifted out, and ensure the service life and the operation reliability and stability of the packer.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The core of the invention is to provide the oil pipe passing packer with the corrugated and net-shaped composite steel skeleton, which has better sealing performance when in setting operation and unsetting operation, can realize smooth switching between the unsetting operation and the setting operation, ensures that the packer can be smoothly lifted out, and ensures the service life and the reliable stability of the operation.
The invention provides an oil pipe passing packer with a corrugated and net-shaped composite steel skeleton, which comprises a skeleton mechanism, an outer rubber cylinder, an inner rubber cylinder 9 and a central pipe 10, and reference is made to fig. 1, 2 and 3.
The skeleton mechanism comprises a second skeleton 3 and a first skeleton 2 symmetrically arranged at two ends of the second skeleton, the first skeleton 2 and the second skeleton 3 jointly form a composite skeleton, the composite skeleton has good rebound performance and extensibility, self rebound force can be utilized to reset under a pressure release state, smooth switching of a packer setting state and a deblocking state is ensured, the packer can be smoothly started when in use, the operation is simple and efficient, the service life of the packer is prolonged, and the influence on underground operation is avoided.
In the present embodiment, the number of the first skeletons 2 and the second skeletons 3 is not limited.
The arrangement of the composite framework can stabilize the bearing of the rubber cylinder system on the premise of not damaging the inner wall of the sleeve 6, reduce the uneven stress distribution and improve the bearing capacity of the packer.
Preferably, a weld is made between the inner side of the first skeleton 2 and the end of the second skeleton 3.
The outer rubber sleeve is sleeved on the outer side of the second framework 3, and when the second framework 3 expands, the outer rubber sleeve expands until being attached to the sleeve 6, so that anchoring with the sleeve 6 is realized, and sealing is formed between the expansion of the outer rubber sleeve and the sleeve 6.
The inner rubber cylinder 9 is arranged on the inner side of the framework structure and is internally provided with a circulation cavity, a certain gap is formed between the outer wall of the central tube 10 and the inner rubber cylinder 9, the gap is a hydraulic cavity, the central tube 10 is provided with a liquid through port 101, and the liquid through port 101 and the circulation cavity are communicated with the hydraulic cavity to form a flow passage of expansion liquid.
The inner rubber cylinder 9 and the outer rubber cylinder are high-elasticity, high-expansion-ratio, high-shear-strength and heat-resistant oil-resistant rubber, and can meet the underground high-temperature high-pressure operation conditions. As a preferable mode, the hardness of the rubber is selected to be 75A and 65A, the material is preferably hydrogenated butyronitrile, and magnetic particles are attached to the rubber, so that when the inner rubber cylinder 9 and the outer rubber cylinder expand to carry out setting operation, the magnetic particles can assist in setting, and the sealing performance of the packer is enhanced.
In this embodiment, the lengths and thicknesses of the inner rubber cylinder 9 and the outer rubber cylinder are not limited, and the thicknesses and lengths of the inner rubber cylinder 9 and the outer rubber cylinder can be increased or decreased in combination with actual operation conditions so as to realize the change of rebound performance and anchoring performance.
The end part of the inner rubber cylinder 9 is sleeved with a hoop protection mechanism, the inner wall of the hoop protection mechanism is connected with the first framework 2, and the end surfaces of the first framework 2 and the inner rubber cylinder 9 can be sealed relatively through the arrangement of the hoop protection mechanism, so that expansion liquid only flows in the inner rubber cylinder 9 and the hydraulic cavity and cannot overflow.
In addition, the material of the hoop protection mechanism is preferably high-strength corrosion-resistant stainless steel, so that the hoop protection mechanism cannot be easily deformed and damaged in the operation process.
The bending shape of the hoop horn mouth of the hoop protection mechanism is in an anti-elliptical state, bending stress can be generated when the hoop protection mechanism is contacted with the first framework 2, the first framework 2 is bent around the inner side of the horn mouth and the vertical direction of the section of the first framework 2, the strain at the end point of the horn mouth is not obvious, the root of the horn mouth is gradually transited to the end part, the stress concentration phenomenon is reduced, the sealing performance of the inner rubber tube 9 and the framework mechanism is enhanced, the abrasion of parts is reduced, and the setting performance is enhanced.
After the expansion liquid reaches the circulation cavity after passing through the liquid through hole 101, the inner rubber cylinder 9 expands to further push the framework mechanism to expand, wherein the stress area of the first frameworks 2 at two sides is gradually increased in the expansion process, the bearing capacity is enhanced, the first frameworks 2 are anchored with the inner wall of the sleeve 6, the stress variation at the bending part of the first frameworks 2 is stable, the hoop protection mechanism connected with the first frameworks 2 is protected, and meanwhile, the second frameworks 3 gradually tighten the expansion outer rubber cylinder to enable the outer rubber cylinder to be attached with the inner wall of the sleeve 6, so that anchoring and sealing effects are realized, and the setting operation is completed; after the expansion liquid returns to the hydraulic cavity through the flow cavity and flows out of the liquid port 101, pressure relief work is realized, at the moment, the inner rubber cylinder 9 and the outer rubber cylinder are retracted to the original state, and the skeleton mechanism is also reset by utilizing the self resilience force, so that the deblocking work is completed. The setting and unsetting operations are simple and efficient, are not easy to damage, can be repeatedly used for many times, and reduce cost.
In addition, the liquid inlet 101 is connected with a hydraulic element through a pipeline, so that the supply and recovery of the expansion liquid are realized.
The skeleton mechanism adopts cold rolling and heat treatment processing technology, so that the damage to the hoop protection mechanism can be reduced, and the sleeve 6 can not be damaged when the anchoring and sealing operation is carried out.
Optionally, a setting releasing mechanism can be arranged at the upper end of the packer, and the packer can be lifted upwards for recovery after decompression and shrinkage, so that the materials and the cost are saved, and the use reliability and the stability of the packer are ensured to the greatest extent.
Optionally, a pressure relief assembly may be disposed at the bottom end of the central tube 10, for example, the pressure relief assembly may include a valve core, a valve seat, and a limiting ring, where the valve core is a sealing conical surface with an equal proportion of increase from inside to outside, and the valve core and the outer end of the valve seat form a seal during operation, and the pressure relief channel is opened and closed by the relative movement of the valve core and the valve seat.
Optionally, the whole structure of the oil pipe passing packer provided by the invention is in streamline design, and the outer side is subjected to fillet and chamfering treatment, so that a certain protection effect is achieved on the sleeve 6. In addition, when the packer is in a setting state, a sliding compensation distance is needed, and the packer rubber and the sleeve 6 are not damaged due to friction.
The oil pipe passing packer with the corrugated and net-shaped composite steel skeleton comprises a skeleton mechanism, an outer rubber cylinder, an inner rubber cylinder 9, a central pipe 10 and a hoop protection mechanism, wherein the skeleton mechanism comprises a second skeleton 3 and first skeletons 2 symmetrically arranged at two ends of the second skeleton, and the situation of uneven stress distribution can be reduced in the expansion or contraction process through the arrangement of the composite skeleton, so that the bearing capacity of the packer is improved; the outer rubber cylinder is sleeved on the outer side of the second framework 3, the inner rubber cylinder 9 is arranged on the inner side of the framework mechanism and is internally provided with a circulation cavity, a central pipe 10 is arranged on the inner side of the inner rubber cylinder 9, a hydraulic cavity is formed between the central pipe 10 and the inner rubber pipe, a liquid through hole 101 is formed in the central pipe 10, the liquid through hole 101 and the circulation cavity are communicated with the hydraulic cavity, expansion liquid is fed into the circulation cavity of the inner rubber cylinder 9 after passing through the liquid through hole 101 and the hydraulic cavity, after entering the inner rubber cylinder 9, the inner rubber cylinder 9 expands to extrude the framework mechanism, the first framework 2 and the second framework 3 expand simultaneously, the outer rubber cylinder expands to be attached to the sleeve 6, sealing and anchoring effects are achieved, and the setting operation of the packer is completed; after the sealing and anchoring operation is finished, the expansion liquid returns to the hydraulic cavity from the circulation cavity, and after the expansion liquid flows out of the liquid outlet 101, the inner rubber cylinder 9 can retract, the framework mechanism resets, and the deblocking operation of the packer is finished; in addition, the inner rubber tube 9 is sleeved with a hoop protection mechanism, and the hoop protection mechanism is connected with the first framework 2 and is used for sealing the end surfaces of the first framework 2 and the inner rubber tube 9, so that the tightness in the setting operation and the deblocking operation can be ensured; the oil pipe passing packer with the corrugated and net-shaped composite steel skeleton can realize smooth switching of deblocking operation and setting operation, ensure that the packer can be smoothly lifted out, and ensure the service life and the operation reliability and stability of the packer.
On the basis of the embodiment, the first framework 2 is a corrugated framework, the second framework 3 is a net framework, and the corrugated angle of the corrugated framework is consistent with the corrugated angle of the net framework.
Referring to fig. 1 and 2, the corrugation of the first skeleton 2 and the net shape of the second skeleton 3 are naturally transited, and the circumferential tips of the two are welded, so as to ensure the uniform expansion rate of the skeleton mechanism as a whole.
The ripple angle of the net skeleton is consistent with the ripple angle of the ripple skeleton, the net skeleton and the ripple skeleton adopt the same function curved surface, and as a preferred implementation mode, the net skeleton and the ripple skeleton adopt the same sine function curved surface, have better elasticity in the process of expansion and contraction by equal proportion, have no relative displacement between the net skeleton and the ripple skeleton, and increase the stability of the whole packer structure.
In this embodiment, on the premise of ensuring the maximum outer diameter of the packer, the sine function curved surfaces of the second framework 3 and the first framework 2 can be adjusted, so that the actual requirements on the casings with different sizes are met, the uniform stability of the stress borne by the casing 6 is ensured, and the applicability of the packer is improved.
On the basis of any one of the above embodiments, the outer rubber cylinder comprises a second outer rubber cylinder 5 and first outer rubber cylinders 4 symmetrically arranged on two sides of the second outer rubber cylinder, and the height of the second outer rubber cylinder 5 is larger than that of the first outer rubber cylinder 4.
Referring to fig. 1 and 2, the second outer rubber tube 5 is disposed in the middle of the entire second frame 3, and the two first outer rubber tubes 4 are symmetrically disposed on two sides of the second outer rubber tube 5, where the distances between the three are equal. The second outer rubber cylinder 5 is higher than the first outer rubber cylinder 4, so that the sealing performance is improved.
In addition, the hardness of the first outer rubber cylinder 4 is different from that of the second outer rubber cylinder 5, the first outer rubber cylinder 4 is hard, the second outer rubber cylinder 5 is softer, the second outer rubber cylinder 5 is firstly contacted with the sleeve 6 in setting operation and plays a main sealing role, and when the outer rubber cylinder expands, the outer rubber cylinder structure formed by the three rubber cylinders can form better stress distribution, so that good sealing timeliness is achieved.
On the basis of any embodiment, a limiting assembly is arranged in the hoop protection mechanism, and the limiting assembly is used for limiting the offset between the central tube 10 and the inner rubber cylinder 9.
A limiting component is arranged in the protective hoop mechanism to limit the relative offset between the inner rubber cylinder 9 connected with the protective hoop mechanism and the central tube 10 arranged in the inner rubber cylinder 9. The relative offset is limited to at least two directions, namely axial and radial, and the specific structure of the limiting assembly is not limited, and can be one or more clamping pieces horizontally, obliquely and vertically arranged or any combination.
Through the setting of spacing subassembly, the relative skew between restriction center tube 10 and the interior rubber tube 9 guarantees the smooth and easy circulation of inflation liquid between the hydraulic pressure chamber, guarantees the operational fail safe nature in inflation or the withdrawal process.
On the basis of any one of the above embodiments, the limiting assembly comprises a pressing cap 12 and a fixing ring 13 connected with the pressing cap, wherein the fixing ring 13 is sleeved on the outer side of the central tube 10 and is connected with the inner rubber cylinder 9, and the pressing cap 12 is sleeved on the end part of the central tube 10.
Referring to fig. 1,2 and 3, the limiting assembly includes a pressing cap 12 and a fixing ring 13 connected with the pressing cap 12, the fixing ring 13 is tightly attached to the pressing cap 12, and simultaneously compresses the inner rubber tube 9 to limit axial and radial offset between the central tube 10 and the inner rubber tube 9.
The fixed ring 13 is composed of an inner back ring and an outer back ring, the assembly of which is symmetrically arranged, and the contact surfaces are inclined surfaces. The fixed ring 13 cover is located the outside of center tube 10 and is connected with interior packing element 9, and when pressing, interior packing element 9 extrudees fixed ring 13, plays the antifriction effect in the inflation in-process, can prevent packing element inflation extrusion and protect hoop mechanism and make it produce wearing and tearing and deformation, improves life, guarantees better sealed effect, anchoring effect.
The pressing cap 12 is sleeved at the end part of the central tube 10 and matched with the fixing ring 13 to press the inner rubber cylinder 9.
On the basis of any embodiment, the fixing ring 13 is provided with a plurality of clamping grooves 131, and sealing rings for pressing the inner rubber cylinder 9 are arranged in the clamping grooves 131.
In the packer installation process, the inner rubber cylinder 9 is tightly attached to the clamping grooves 131, sealing rings are arranged in the clamping grooves 131, and the inner rubber cylinder 9 is tightly pressed and fixed by using the sealing rings, the fixing rings 13, the pressing caps 12 and the like, so that the offset of the inner rubber cylinder 9 is avoided.
As a preferred embodiment, the plurality of clamping grooves 131 are distributed in a zigzag shape to clamp the outer wall of the inner rubber cylinder 9, so that the inner rubber cylinder 9 is prevented from sliding axially, the sealing performance of the packer during anchoring is enhanced during hydraulic expansion, and the axial displacement is avoided.
Alternatively, the fixing ring 13 and the clamping groove 131 may be separately arranged, and the clamping groove 131 is arranged on the other limiting member.
On the basis of any embodiment, the inner rubber cylinder 9 is connected with the hoop protection mechanism through a first fastener 8 which is transversely arranged, and a back ring 14 which is longitudinally arranged is also arranged between the fixed ring 13 and the central tube 10.
The inner rubber tube 9 is connected with the hoop protection mechanism through a first fastener 8 which is transversely arranged, and the first fastener 8 passes through the hoop protection mechanism, the framework mechanism and the inner rubber tube 9 to transversely fix the inner rubber tube 9, so that transverse sliding is avoided.
A back ring 14 is arranged between the fixing ring 13 and the central tube 10 in a longitudinal direction, the fixing ring 13 is sleeved on the outer side of the central tube 10 and is connected with the inner rubber cylinder 9, and the back ring 14 further limits the offset between the inner rubber cylinder 9 and the central tube 10, so that the longitudinal sliding is avoided.
On the basis of any of the above embodiments, the packer further comprises a push assembly, the push assembly comprising: the pushing piece 17 is arranged in the hydraulic cavity; the piston ring 19 is connected with the moving end of the pushing piece 17, and the piston ring 19 can move up and down to push the expansion liquid; and a driving member 18 connected to the fixed end of the pushing member 17.
Referring to fig. 1,2,3 and 6, the driving member 18 may be a motor, an air cylinder, an oil cylinder, etc., and the driving member 18 drives the pushing member 17 to push the piston ring 19 to move downward to push the expansion liquid, so as to uniformly push the expansion liquid into the circulation cavity of the inner rubber tube 9, uniformly expand the inner rubber tube 9, and further operate on the skeleton mechanism and the outer rubber tube; when the driving piece 18 drives the pushing piece 17 to push the piston ring 19 to move upwards, the expansion liquid directly flows out of the liquid through hole 101 to realize pressure relief work, the inner rubber cylinder and the outer rubber cylinder lose pressure and retract, the unsealing is completed, and the sealing ring can be lifted upwards for recovery, so that the damage to the hoop protection mechanism is avoided.
It should be noted that the up and down directions are only directions in relative terms, and the up and down pushing of the piston ring 19 can achieve switching between the unset and the set states.
In addition, the sealing rings are required to be arranged on the inner side and the outer side of the piston assembly, so that the expansion liquid is prevented from leaking, and the sealing effect of the packer is ensured to be stable.
On the basis of any embodiment, the framework mechanism and the inner rubber cylinder 9 are vulcanized and formed, and the outer rubber cylinder and the second framework 3 are vulcanized and formed.
The framework mechanism and the inner rubber cylinder 9 are vulcanized and formed, and the outer rubber cylinder and the second framework 3 are vulcanized and formed, namely, the inner rubber cylinder, the outer rubber cylinder and the framework mechanism are formed by adopting a vulcanization process, are tightly covered, do not have relative displacement to expand the framework mechanism, realize complete filling of grooves between the inner rubber cylinder and the framework mechanism, enable macromolecules of the rubber linear structure to be crosslinked into three-dimensional netlike macromolecules, obviously improve the physical and chemical properties of the inner rubber cylinder and the outer rubber cylinder, and ensure the overall tightness, stability and durability of the packer.
On the basis of any embodiment, the hoop protection mechanism comprises a first hoop protection mechanism 1 and a second hoop protection mechanism 7 which are respectively arranged on two sides of the framework structure, the first hoop protection mechanism 1 and the second hoop protection mechanism 7 are respectively provided with a pressure sensor 15, and one side of the pressure sensor 15 is in signal connection with an amplifier 16.
Referring to fig. 1 and 7, the first and second hoop mechanisms 1 and 7 are respectively provided with a pressure sensor 15 to realize real-time pressure monitoring. An amplifier 16 is connected to one side of the pressure sensor 15 in a signal manner, the pressure signal is fed back to a control mechanism or a table through the amplifier 16, and a liquid is used as a medium for transmitting an acoustic wave signal through the amplifier 16.
Two pressure sensors 15 on the first hoop protection mechanism 1 and the second hoop protection mechanism 7 correspondingly need two amplifiers 16 to transmit two pressure signals to a control mechanism or a workbench, and the pressure difference between the upper side and the lower side is determined through detection and analysis of sound wave signals so as to judge the stability and timeliness of packer sealing.
In this embodiment, the control unit is preferably a single-chip microcomputer, and the response is rapid and accurate.
The structure design and test are carried out on the oil pipe passing packer with the corrugated and net-shaped composite steel skeleton, the preferable design is carried out on the size parameters, materials and the like of the parts of the packer, and the packer with the whole length of 670mm, the maximum diameter of 84mm in the retraction state and the whole symmetrical structure is designed. The expansion rate of the packer can reach 200% through simulation tests of indoor pressure bearing, effective sealing and the like, the packer can resist the temperature of 90-120 ℃ and the pressure bearing of 30Mpa after sealing, and the packer can be suitable for the operation requirement of sealing a seven-inch sleeve pipe by a 4-1/2 oil pipe (namely, an oil pipe with the outer diameter of 114.3mm, the wall thickness of 6.88mm and the inner diameter of 100.54 mm), can also be suitable for the operation requirement of sleeves 6 with different sizes, has excellent rebound performance, can be repeatedly used, is safe and reliable in operation, and reduces the operation cost and the operation cost.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The oil pipe passing packer with the corrugated and net-shaped composite steel skeleton provided by the invention is described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.