Packer. RU patent 2245986.
 Packer / 2245986Packer has body in form of pipe, whereon collar compactors are placed with limiting washers, saddles for locking tool dropped from surface, cover, upper and lower fixing elements, made in form of anchoring assemblies, upper conical bushing, rigidly connected to pressing bushing and movably to the body, lower conic bushing, made rigidly together with body, guide of this conic bushing made in form of plate spring, placed by one end moveably in guiding groove in lower portion of lower die with teeth, and by other end fixed rigidly on greater diameter of this conic bushing, auxiliary pipe, placed inside the body. Packer in lower portion is provided with check valve, placed inside recess of body, concurrently being also the body of valve. Oppositely to valve saddle on same axis stepped locking bushing is placed with possible sliding inside body recess with limited drive and possible overlapping of radial grooves made in body, which, in its turn, is rigidly connected to auxiliary pipe via shear pin. Between stepped locking bushing and saddle compression spring is placed. Fixing elements of collar compactors are made in form of comb with inner teeth and outer conic generators in nose portion. On the side of collar compactors these are enveloped by inner conic portion of compression bushing, in its turn rigidly connected to upper conic bushing, and on the other side combs with inner teeth are placed sliding-moveably in radial grooves of guiding bushing placed between ends of upper conic bushing and inner conic portion of compression bushing with possible engagement by inner teeth of comb to slanting walls of body groove and interaction to all elements of this assembly. |
 Mechanical packer system / 2246604System has upper and lower packers, each of which has body, shaft, anchor, compactors, and pipes, placed between packers. In shaft of upper packer a copier is made with fixing device of transporting and working position of anchor and a sub. The latter is mounted with possible axial displacement and rotation around the copier. Sub is placed on pipes between packers, mated to lower packer and has no capability for axial rotation and displacement relatively to their axis in operating position of lower packer. On lower packer shaft a copier is made with possible axial displacement with it for interaction with anchor and its displacement from transporting position to operation position. |
 Packer testing stand / 2247222Stand has imitators of casing and lifting columns with packer between them, means for heating casing column imitator, main hydraulic cylinder for axial loading and unloading of packer, pumps to create pressure. Stand is provided with additional hydraulic cylinder with hollow rod and cylinder, connected to rod of min hydraulic cylinder. Additional hydraulic cylinder is encased in the body, rigidly connected to main hydraulic cylinder and imitator of casing column. In additional hydraulic cylinder a ring-shaped piston is placed with conical skirt, interacting with keys with possible periodical supporting against the body through windows in said cylinder and below keys spring-loaded ring-shaped pusher is moveably mounted. In hollow of imitator of lifting column a floating piston is positioned, this hollow and hollow of the hollow rod are interconnected and also connected to hollow above ring-shaped piston. |
 Device for isolating inter-tubular space in the well / 2247223Device includes hollow body with a row of vertical apertures, a collar, pusher bushing, placed on body with possible interaction with collar, cone, mounted on the body, cylinder, connected to cone, screw-thread dies with die holder, mounted on the body with possible extension of dies in radial direction during interaction with cone, saddle and shear screws. According to invention in die holder additional through radial apertures are made, wherein sockets are mounted with possible extension in radial direction. Inner hollow of die holder is connected to inner hollow of body by a row of radial apertures. In pusher bushing through radial apertures are made, wherein sockets are mounted with possible extension in radial direction. Pusher bushing is rigidly fixed to the body, and its inner hollow is connected to inter-tubular space below the collar. |
 Device for isolation operations in wells / 2249094Device has body with radial apertures, two compacting assemblies thereon and valve assembly between them. Each compacting assembly comprises a collar, stopping branch pipe, cylinder, forming a ring-shaped hollow with the body, wherein a bushing is placed. In upper compacting assembly ring-shaped hollow is covered by plug from lower side, which is fixed in cylinder and interacts with collar, cylinder is connected to body by cams, placed in radial apertures of plug and in ring groove of body, bushing is made stepped, long step of which interacts with cams and is fixed by shear screws from displacement in ring plane, which is connected to well. In lower compacting assembly bushing is provided with holder, on the body a cone is mounted, interacting with sockets, placed in grooves of stopping branch pipe, which is fixed on the body by shear screws. |
 Two-packer device / 2249669Device has shaft with radial channels and return valve, upper and lower compacting elements. Inside the shaft a hollow spring-loaded moving rod is placed. It has radial apertures and recesses. Between apertures a throttle is rigidly placed. On upper portion of rod a piston is placed. Working hollow, formed between rod with piston and barrel, fixed on inner portion of shaft, is connected to above-packer space of well by radial aperture, made in barrel wall. Working hollows of upper and lower compacting elements are connected by axial channel, made in shaft and ring channel, formed between inner and outer pipes, connecting lower compacting element to the shaft. On upper portion of pipe through radial apertures are made and cylindrical recess, matching rod diameter, in which rod a plug is place. Outer diameter of upper end portion of rod equals outer diameter of lower rod portion. |
 Self-detaching bidirectional action packer with electromechanical drive / 2250351Packer has body, in which electric engine, reducer with output shaft, connected to screw couple, which is connected to traction, having holding rods on lower portion with spring for transfer of axial force to central rod, having a shelf in upper portion as well as recess and cuts, and in inner portion - compacting rings and stopping nut, are positioned. Packer has shell, having conical surface on inner portion, special part with shelves, shear ring placed in grooves of said special part and holding segments, immobile bushing connected fixedly to special part. Packer has packer rubber, saddle, rigidly connected to special part, moveable flange and two cones, placed oppositely to each other, dies, moveably placed on cones, traction, jointly connected to dies, branch pipe, fixedly placed on body, moveable bushing, balls, pressed by spring and screw for connection of special part to shell, cable of rope, being a carrying cable and feeding electric engine via filament, shear washer, pressed by nut. When packer is removed, engaging assembly is utilized, which includes pusher, screwed on lower portion of screw couple screw, cut holder and cover. Through apertures are made on special part and moveable flange for connection of above-packer and below-packer well hollows. |
 Packer / 2251614Packer includes shaft with outer bored surface and bead and sealing members supported by the bead. Packer also has air cylinder forming annular cavity together with packer shaft. Cavity is connected with shaft interior through radial channels. Packer includes anchoring means. Lower anchoring means includes cone with slips and slip holder having bored inner orifice and threaded orifices. Lower anchoring means rests upon the bead and is connected to the shaft by shear screws installed in threaded orifices of slip holder. Shaft defines inner bored diameter and includes sliding bush located inside shaft. Shaft is provided with lower and upper grooves for sealing rings receiving and with outer grooves for cams and additional shear screws installation. Outer grooves are located between lower and upper ones. Slots are formed below bead on outer shaft surface for installing cams with limited radial travel. Threaded orifices are formed on outer shaft surface above inner groove thereof. Arranged into groove are additional shear screws to secure sliding bush in its initial position. The slip holder is freely installed on shaft or is spring-loaded. Support-moving bush is installed in inner bored orifice of slip holder between shear screws and cams. Support-moving bush is provided with facet formed from cam side and contacts with cams along mating facets upon shearing of shear screws. Free travel between cams and end of support-moving bush exceeds shear screw diameters to provide shearing thereof. When sliding bush is installed in fixed position cams extend above an outer shaft surface generator to provide displacement of support-moving bush and cut of shear screws. When sliding bush is located in operating position cams are located below outer shaft surface generator and move in radial direction into outer groove of sliding bush to provide free cam movement under support-moving bush and shear screws. |
 Packing device of additional casing column / 2254441Device has body, made in form of branch pipe with elastic collar mounted on it, expanding assembly with cone, shear element, gear, lowered on pipes column into additional casing column and interacting with expanding assembly from above. Expanding element is positioned in upper portion of branch pipe and locked with its cone directed downwards, gear is made in form of pusher in lower portion and anchor assembly in upper portion. Pusher is made in form of hydraulic cylinder, made with possible pressure from above on expanding assembly and provided with piston and hollow rod, which is connected to piston rigidly, and to pipes column - hermetically with possible upward axial displacement. Anchor assembly is made in form of dies, mounted on hollow rod with possible radial movement outwards during movement of hollow rod upwards relatively to pipes column. Shear element holds hollow rod relatively to pipes column during lowering into well. |
 Packing device of additional casing column / 2254442Device has packer, mounting tool and anchor assembly. Packer expander is mounted in upper portion of body, and anchor assembly - above hydraulic chamber of mounting tool. Hydraulic chamber cylinder is mounted with possible displacement relatively to rod and hydraulically connected to inner space of device. Body of anchor assembly is provided with sockets, in which spring-loaded dies are mounted, which are activated by hydraulic effect formed in tubing pipes column, on which device is lowered into well. |
FIELD: oil and gas extractive industry.
SUBSTANCE: packer has body in form of pipe, whereon collar compactors are placed with limiting washers, saddles for locking tool dropped from surface, cover, upper and lower fixing elements, made in form of anchoring assemblies, upper conical bushing, rigidly connected to pressing bushing and movably to the body, lower conic bushing, made rigidly together with body, guide of this conic bushing made in form of plate spring, placed by one end moveably in guiding groove in lower portion of lower die with teeth, and by other end fixed rigidly on greater diameter of this conic bushing, auxiliary pipe, placed inside the body. Packer in lower portion is provided with check valve, placed inside recess of body, concurrently being also the body of valve. Oppositely to valve saddle on same axis stepped locking bushing is placed with possible sliding inside body recess with limited drive and possible overlapping of radial grooves made in body, which, in its turn, is rigidly connected to auxiliary pipe via shear pin. Between stepped locking bushing and saddle compression spring is placed. Fixing elements of collar compactors are made in form of comb with inner teeth and outer conic generators in nose portion. On the side of collar compactors these are enveloped by inner conic portion of compression bushing, in its turn rigidly connected to upper conic bushing, and on the other side combs with inner teeth are placed sliding-moveably in radial grooves of guiding bushing placed between ends of upper conic bushing and inner conic portion of compression bushing with possible engagement by inner teeth of comb to slanting walls of body groove and interaction to all elements of this assembly.
EFFECT: higher reliability.
5 dwg
The invention relates to the oil and gas industry, in particular to devices used in the operation and repair of wells, and for uncoupling wellbore during technological operations impact on the reservoir.
Known interval packer to isolate the wellbore during technological operations impact on the formation, consisting of upper and lower sealing elements with stems and lock the compressed position of sealing elements mounted on the string of pipe with a coupling at the lower end [1].
Column pipes in the upper part is connected with tubing (tubing) transition coupling. The valve mechanism is in the form of a stepped bushing mounted in concentric inverted Cup, and a control coupling with a pin rigidly mounted on its lateral surface. Inverted glass in the upper part is connected by a shell having a longitudinal groove and a stopper. In the lower part of the pipe is connected with the saddle. The saddle is made with intersecting radial and axial holes. In the axial hole placed with overlapping radial hole of the stop element with the top of the ledge. Stepped sleeve is made with two outer annular projections and two shaped grooves, upper and lower, for placement of the pin of the control sleeve and the protrusion of the locking element. Transition coupling has rigidly secured to it a pin mounted in the longitudinal groove of the shell.
The disadvantage of the packer is narrow technological possibility of its use, as it applies only to divide the cavity annulus during technological operations, and the inability to ensure the reliability of the valve packer. When any design such a closing element made in the form of a pin (plunger) from the upper ledge with the console considerable length, bending, breaks the axial hole of the valve and jams in it. During the ascent and descent tubing stepped sleeve rotates, and with it the sloping curly groove is lowered or raised this console locking element. When the rotation speed of the inclined sleeve is made of a wall of the groove, where the protrusion of the locking element, pressure is exerted not only vertically down or lift up the plunger of this valve element, and bend in the direction of the rotation speed of the sleeve, and therefore in the process of opening and closing the valve after a few cycles Petrovci hole seat is broken and then there is the depressurization of this packer.
Despite the complexity of the design of the clamping node lip seals [made in the form of a pressure sleeve with an internal ledge at the end of it, and placed concentric with the movable sleeve with a dog slidable it relative to the body, while it (Bush dog) made with slits in the collet and inner end clamps (teeth) with the ability to capture them for the sloping walls of the groove of the outer pipe], it is not enough reliable fixation due to slippage of the sleeve with the dog (the inner end of the shoulder) at the time of a hook for the inclined grooves of the casing and, as a consequence, the depressurization pokerwise site. In addition, limited its scope because of the impossibility of use in other processes without additional locking bodies.
The objective of the invention is the expansion of technological capabilities of the packer, namely improving the reliability of fixing the sealing site while increasing the reliability of the sealing annulus and the simplification of the structure as a whole.
The problem is solved in that in the known packer, comprising a housing made in the form of a pipe that hosts the locking elements of the lip seals and lip seals, under saddle discharged from the surface of a stop valve, a casing, upper and lower fixing elements made in the form of zakurivaya knots, sloping groove made on the outer surface of the housing, the upper tapered sleeve rigidly connected with the push sleeve, the lower cone sleeve, made strictly with the case, this guide cone sleeve,
made in the form of a leaf spring placed lower end movably in the guide groove in the bottom of the die with teeth, and the other end rigidly attached to the large diameter of this tapered sleeve, a supporting tube, located inside the housing, while zakalivayuschie nodes, made in the form of plates with teeth placed on the guide bushings and are located in the upper and lower parts of the concentric casing of conical parts of the bushing, and the upper die with teeth and a small diameter upper tapered sleeves are made sloping upwards, and the lower die with teeth and a small diameter lower cone sleeve is made pointing downwards, and lip seals with restrictive washers placed between the ends of the cover and the lower cone sleeve, and saddle under discharged from the surface of the lock body mounted rigidly to the upper end of the conical sleeve, the packer in the lower part is equipped with a check valve placed inside the bore of the body, simultaneously the valve body and against the valve seat on one axis installed manual shut-off sleeve slidable within the bore of the housing with a limited run for overlapping radial grooves made in the case, which, in turn, rigidly connected with the supporting tube by means of the shear pin, and between the manual shut-off sleeve and the saddle is placed release tab spring, with the locking elements of radial shaft seals made in the form of combs with inner teeth and outer cone forming the forward part of the side lip seals,
and they covered the inner cone part of the push sleeve, in turn, is rigidly connected with the upper tapered sleeve, and on the other side of the comb with internal teeth arranged ov-movably in the radial grooves of the guide sleeve disposed between the upper ends of the conical sleeve and inner cone part of the push sleeve with mesh combs for sloping walls of the housing groove and interaction with all elements of this site., The task is also solved by the fact that geophysical head in the upper part rigidly connected with the housing by means of shear pin and the supporting tube by means of the screw while the screw is attached to the auxiliary tube rigidly, but with geophysical head it is connected movably along the axis.
In the transport position, the upper tapered sleeve and casing rigidly connected by shear pins with the auxiliary tube and the casing, movably mounted between them, has a through longitudinal radial slots against these shear pins.
Salient features of the claimed invention in comparison with the prototype are:
- packer in the lower part is equipped with a check valve placed inside the bore of the body, simultaneously the valve body and against the valve seat on one axis installed manual shut-off sleeve slidable within the bore of the housing with a limited run for overlapping radial grooves made in the case, which, in turn, rigidly connected with the supporting tube by means of shear pins, and stepped between the locking nut and the saddle is placed spring release tab;
- fixing elements of radial shaft seals made in the form of combs with inner teeth and outer cone forming at the front, from the side of the lip seals, and they covered the inner cone part of the push sleeve, in turn, is rigidly connected with the upper tapered sleeve, and on the other side of the comb with internal teeth arranged ov-movably in the radial grooves of the guide sleeve disposed between the upper ends of the conical sleeve and inner cone part of the push sleeve with the possibility of engagement of the internal teeth of the comb over the sloping walls of the housing groove and interaction with all elements of this node.
This embodiment of the design of the packer in comparison with the prototype will improve the reliability of fixation and thereby increase the reliability of the sealing annulus and enhance technological capabilities and the scope of its application while simplifying the design as a whole.
The above salient characteristics were unknown to us patent and scientific and technical information and in conjunction with the known help to solve the problem posed by the invention, and in this connection, we announced a significant distinguishing features of the “New”.
In the claimed invention made working drawings and prototype, which has been successfully tested on Vuktyl gas condensate field. Can easily be made in terms of craft workshops. In this regard, we believe that the invention conforms to the criterion “Industrial applicability”.
The claimed invention is not obvious to a person skilled in this field and therefore corresponds to the “Inventive step”.
Figure 1 shows the packer, the descent on the rope in the hole in the transport position; figure 2 - after removing the auxiliary tube, the working position; figure 3 is a section a-a in figure 2; figure 4 is a cross-section B-B in figure 2; figure 5 is a section b - b In figure 2.
The packer consists of a housing 1 made in the form of a pipe that hosts lip seals 2 with restrictive washers 3, seat 4 under discharged from the surface of the locking body casing 5, the upper and lower locking elements made in the form of zakurivaya nodes, the upper cone of the sleeve 6, is rigidly connected with the push sleeve 7 and is movable with the housing 1, the lower cone sleeve 8 made rigidly with the housing 1, the guide 9 of this conical sleeve, made in the form of a leaf spring placed lower end movably in the guide groove 10 in the lower part of the lower die 11 with teeth (see figure 5), and the other end rigidly attached to the large diameter of this tapered sleeve 8, the auxiliary tube 12, is located inside the housing 1.
Zakalivayuschie nodes, made in the form of plates with teeth placed on the guide bushings and are located in the upper and lower parts concentric with the casing, and the upper die 13 with the teeth and the small diameter upper conical sleeve 6 are directed upwards, and the lower die 11S teeth and a small diameter lower cone sleeve 8 are directed down.
Lip seals 2 with restrictive washers 3 are placed between the ends of the cover 7 and the lower cone sleeve 8. Seat 4 under discharged from the surface of the stop valve (bulb, tube) mounted to the upper end of the conical sleeve 6.
Packer in the lower part is equipped with a check valve 14, is placed within the bore 15 of the housing 1, and simultaneously the valve body. Against the seat 16 of the valve 14 on the same axis installed manual shut-off sleeve 17 slidable within the bore 15 of the housing 1 with limited progress and the possibility of overlapping radial grooves made in the body, which is rigidly connected with the supporting tube 12 by means of the shear pin 18. Between the manual shut-off sleeve 17 and the saddle 16 is placed release tab spring 19. The saddle 16 in the bore of the housing is fixed by means of transferable fitting 20.
The locking elements of radial shaft seals made in the form dies 21 with the internal teeth 22 and the outer cone 23 forming in the nasal part, by lip seals 2 they covered the inner tapered part 24 of the pressure sleeve 7, in turn, is rigidly connected with the upper conical sleeve 6, and on the other side of the comb 21 with the internal teeth 22 located ov-movably in the radial grooves 25 of the guide sleeve 26 disposed between the ends of the upper conical section 24 of the pressure sleeve 7 with the possibility of engagement of the internal teeth 22 of the comb 21 for sloping walls of the grooves 27 of the housing 1 and the interaction with all the elements of this node.
Below the lower cone sleeve 8 has a cover 5 covering the inner bore 28 of the lower dies 11 with teeth.
Geophysical head 29 in the upper part is connected to the housing by means of shear pin 30 and the auxiliary pipe 12 by means of the screw 31. The screw 31 is attached to the supporting tube 12 is rigidly and with geophysical head 29 it is connected movably along the axis.
In the transport position, the upper conical sleeve 6 and the casing 5 are rigidly connected by means of shear pins 32, 18 with the auxiliary pipe 12 and the casing 1 is mounted movably between them and has a through longitudinal radial slots 33, 34 against these pins 32 and 18.
Shear pins 18, 30, 32 must be designed and installed based on the process conditions.
After stopping the descent of the packer to the desired depth of the well and lifting force required to compress the sealing cuff 2 at 20...25 mm for the liberation of the lower dies 11 with the teeth of the casing 5, and pre-fixing in position, and at this level, and after that first need to cut the upper pin 30 connecting geophysical head 2 with the body 1, and then the rest of shear pins 18 and 32 connecting the upper conical sleeve 6 and the lower casing 5 with the auxiliary pipe 12. Item 35 - tubing (tubing).
PACKER WORKS AS FOLLOWS
Packer with tail lowered into the borehole to the required depth on the cable for geophysical head 29 (tail conventionally not shown). At the end of the descent of the upper die 13 with the teeth engages with the wall of the tubing 35. Then the cable pull up on 20...25 mm for geophysical head 29 that is connected with the housing 1 with the force required to compress the lip seals 2 and the output of the lower dies 11 with the teeth of the casing 26. Thereafter, the lower die 11 with teeth pressed against the inner wall of the tubing, the sleeve seals 2 are compressed to the desired size and seal the annular space between the body of the packer 1 and the inner wall of the tubing, and the saddle 4, the upper conical sleeve 6, the push sleeve 7, the comb 21 with the internal teeth 22, the guide Bush 26, the casing 5, the screw 31 with the supporting tube 12 remains in place. This lifted geophysical head 29 with the body 1, the lower cone sleeve 8 and installed on her lower die 11 with the teeth. Then the lower die 11 with the teeth out of the fixed casing 5 and the plate guide spring 9 press them to the wall of the tubing. When this occurs, the engagement of the lower dies 11 with the teeth with the inner surface of tubing that will prevent from falling packer with a tail on the bottom of a well. It also engages combs 21 with the internal teeth 22 with the groove 27 with the housing 1. When this occurs, the detent lip seals 2 in a compressed position.
With further increase efforts on the cable above the calculated cut first main shear pin 30, and then are cut 32 and 18. Then geophysical head 29, the auxiliary retaining tube 12 with the screw 31 is retrieved to the surface. But if you continue lifting the auxiliary retaining tube 12 together with her lifted stepped locking sleeve 17, associated with the same pin 18, which (manual shut-off bushing 17), having a lower flange bore 15 of the housing 1, stops, finishing in the top (on the diagram) the position and blocking the technological gap 34 of the housing 1. Here, the pin 18 is permanently cut off from the inner side of the auxiliary retaining tube 12. Thus, technological overlap the slit 34 of the housing 1, and a stepped retaining sleeve 17 is fixed in this position by release of the spring 19.
Check valve (POS. 14, 16, 20)mounted on the lower part of the packer, performs its normal function when performing technological operations.
Then lowered into the well on a logging cable stopper (locking element), the figure is not shown, resting on the tapered surface of the seat 4, is fixed to the upper end of the conical sleeve 6. Then in the tubing pump working fluid under pressure required for full disclosure of lip seals 2 for the secure sealing of the annulus. When this occurs, the sealing annulus, the final fixation of radial shaft seals 2 in a compressed position and zakodirovannie lower dies with the teeth 11 of the inner wall of the tubing from sliding down into the well packer with a tail.
After these operations, the well is put into operation. The rise of the packer with the tail together with the tubing.
The proposed invention can be used in the implementation of the following technological operations:
for education camera replacement tubing string;
to isolate intervals of the formation;
for extraction of the increased volume of fluid in oil and gas wells under conditions of abnormally low reservoir pressure;
- to ensure a safe environment conservation and other
Sources of information
1. USSR author's certificate No. 1576685, CL E 21 In 33/112, publ. 07.07.1990.
Packer, comprising a housing made in the form of a pipe that hosts the locking elements of the lip seals and lip seals, under saddle discharged from the surface of a stop valve, a casing, upper and lower fixing elements made in the form of zakurivaya knots, sloping groove made on the outer surface of the housing, the upper tapered sleeve rigidly connected with the push sleeve, the lower cone sleeve, made strictly with the case, this guide cone sleeve, made in the form of a leaf spring placed lower end movably in the guide groove in the bottom of the die with teeth, the other end rigidly attached on the large diameter of this tapered sleeve, a supporting tube, located inside the housing, while zakalivayuschie nodes, made in the form of plates with teeth placed on the guide bushings and are located in the upper and lower parts concentric with the casing, and the upper die with teeth and a small diameter upper tapered sleeves are made sloping upwards,
and the lower die with teeth and a small diameter lower cone sleeve is made pointing downwards, and lip seals with restrictive washers placed between the ends of the cover and the bottom cone bushings and under saddle discharged from the surface of the lock body mounted rigidly to the upper end of the conical sleeve, characterized in that the packer in the lower part is equipped with a check valve placed inside the bore of the body, simultaneously the valve body and against the valve seat on one axis installed manual shut-off sleeve slidable within the bore of the housing with limited progress and the possibility of overlapping radial grooves made in the case, which in turn, rigidly connected with the supporting tube by means of shear pins, and stepped between the locking nut and the saddle is placed release tab spring, with the locking elements of radial shaft seals made in the form of combs with inner teeth and outer cone forming at the front, from the side of the lip seals they covered the inner cone part of the push sleeve, in turn, is rigidly connected with the upper tapered sleeve, and on the other side of the comb with internal teeth arranged ov-movably in the radial grooves of the guide sleeve disposed between the upper ends of the conical sleeve and inner cone part of the push sleeve with the possibility of engagement of the internal teeth of the comb over the sloping walls of the housing groove and interaction with all elements of this node.,