GB2098670A - Peristaltic fluid-machines - Google Patents

Abstract

In a rotary pump for eg. medical purposes, a wheel 5 with rollers 6 for compressing a pumping tube 1 is driven by an electric motor 13 whose rotation axis is perpendicular to that of the wheel so that the pump can be accommodated in a comparatively shallow flat casing 12. The motor and the wheel may be inter-connected by speed-reducing toothed bevel-gears 21, 22. The operative portion of the pumping tube may be supported by a spring-loaded platen 2, which can be held in a retracted position by a resilient tongue 27. <IMAGE>

Description

SPECIFICATION A paristaltic pump The present invention is with respect to a peristaltic pump especially for medical purposes and more specially an enteral pump for artificial feeding with an electric motor and having a flexible pipe element acted upon by a wheel with rollers thereon for peristaltically moving material to be pumped along the pipe element by the rollers on the wheel rolling the element against a rounded backup wall, which is radially spaced from the wheel.

An examples of such a peristaltic pump of the prior art may be seen for example in German Offenlegungsschrift specification 2,500,463, which has a generally cylindrical housing made in four pieces placed next to each other axially, that is to say a battery part, a middle partforthe control systems, a motor part and a pump part next to the side, opposite to the battery part, of the motor part. The wheel with the rollers is, in this respect, normal to the axis of the electric motor and the pipe element for peristaltic pumping purposes is supported on wall parts round the rollers, such wall parts at the same time forming the wall of the cylindrical housing at the end in question.

For a generally rod-like design of the casing of this known peristaltic pump so that the pump, if made with a small overall size, may be taken around by the user with him or her, the diameter of the casing cylinder must be within a certain upper limit.

Because the wheel with the rollers on its outer edge has to have a very much smaller diameter than the casing width (because, between the outer side of the casing and the rollers there is to be at least space for the pipe element and the backup wall with its support part) the wheel with the rollers necessarily has to have a very small diameter. The outcome of this is that the peristaltic pipe element has to be positioned in a curve with a generally small diameter round the edge of the small wheel, the wheel then having to be turned at a high speed to get the desired pumping rate. Such a high speed of the wheel with the rollers does, however, make for loud operation, something which is very undesired if the pump is to be taken around by the user all the time with him.

Furthermore, there are undesired loading effects on the pipe element which has a very small radius, the working life of the pump then no longer being the 4000 to 5000 hours as a possible lower limit, but lower values. Lastly, the pumping function is likely to be second rate because the rollers placed on a body with a small diameter and, for this reason, having a small spacing between are only in a position of peristaltically pumping at a low rate between the nip between by them on the pipe element.

Because furthermore, the wheel with the rollers thereon is fixed on the shaft of the driving motor, quite in addition to the limited amount of space on hand in the pump, a small diameter of the wheel is necessary because the speed of the motor is to be stepped down to the speed of the wheel in a single stage of gearing. Furthermore, with a small wheel diameter, the speed of the motor has to be decreased to values, which for an electric motor, are very low, for pumping at low rates. Such low motor speeds are in fact only possible with high-price special-purpose motors. Normal battery powered DC motors may not be used because they have a starting speed of about 100 rpm, this being not nearly low enough for pumping at the desired low speed, in view of the small diameter of the wheel.

Although it would be possible to have step-down gearing with coaxial input and output shafts between the shaft for driving the wheel with the rollers on the one hand and the shaft of the electric motor on the other, such gearing being for example in the form of an epicyclic system so as to give the desired step-down ratio, such a system is complex and likely to be the cause of trouble conditions. Furthermore, for using such gearing, the axial overall size of the pump would be increased because the pump part, the motor part, the control part and the battery part would have to be put one after the other in line.

On the other hand, one purpose of the present invention is that of designing a peristaltic pump of the sort noted making a flat, compact mechanical design possible without any undesired limits on the diameter of the wheel with the rollers.

For effecting this purpose, and further purposes, the axis of turning of the wheel is normal to the axis of the electric motor.

Because the axis of the wheel is normal to that of the electric motor, the width of the wheel (its largest dimension) is parallel to the direction of the length of the electric motor, this length being the greatest dimension thereof. In a direction normal to these main dimensions it is then, for this reasons, only necessary to have space for the thickness of the wheel and the thickness or the diameter of the electric motor. Separate from the question of the diameter of the wheel, a very flat design is produced so that the peristaltic pump's casing may be generally flat and rectangular, it resting flatly against the body of the user and hardly being seen, if at all.The breadth of the housing is, in comparison with its thickness, hardly important so that, with respect to the diameter of the wheel with the rollers, on which the width of the housing is generally dependent, there are no further conditions to be kept to with respect to the size of the unit. For this reason, a generally large diameter wheel with the rollers may be used without any undesired effects. With such a size of wheel, a desired pumping rate may be produced with the wheel turning at a low speed. A further outcome of this design is that the pump will be quiet in operation with exact rate control and, if the casing is block-like or rectangular, it will be possible to have room for batteries or the like on the two sides of the electric motor within the corners of the casing, such corners being otherwise empty because the wheel with the rollers is round and not rectangular.Putting it differently, the batteries or the like take up space which would not otherwise be used and do not have to be put in special parts of the casing which would make it broader or longer. Because the axes of the wheel with the rollers and of the electric motor are normal to each other, the gearing therebetween may have a very high step-down ratio of at least 1:100 and more specially more than 1 :500 using a simple pinion keyed on the electric motor's shaft and run ning against teeth on the outer edge of the wheel.

For this reason, the step-down gearing does not take up any further space.

Afurtherpointto be kept in mind is that in the peristaltic pump of German specification 2,500,463 the backup wall for supporting the flexible pipe element is made as strong as possible so that it is not pushed back by the rollers rolling on and squeezing the pipe element, the wall stretching for an angle of about 180 degrees round the wheel, which has four equally spaced rollers. The backup wall itself has a support part running out past the two side ends of the wall, such ends of the support part ending in a locking part, necessary because the support together with the locking part is to be responsible for forming the cylindrical outer side of the housing of the peristaltic pump.While it is true that elastic bending of the support part is possible in the sense that its ends may be bent further away from each other elastically so as to take off the locking part and the support part itself if, for example, a new pipe element is to be put in place, such elastic bending is limited to an elastic design of the support part which is curved through more than 180 degrees. When the support part is so stiff that, without respect to the function of the peristaltic pump the backup wall may be thought of as being stiff and not giving way in any respect.

In this respect there are a number of shortcomings: For example, upon putting in a new pipe element, the locking part and the support part have to be completely taken off the pump and put down so that, in some cases, they may be damaged or become dirty or there may sometimes be a chance of loss of such parts.A further point is that the backup wall, behaving as a completely stiff body in operation, has to be produced very true-to-size, and, for this reason, at a high price, such stiffness being necessary because the rollers (which are so supported on the wheel that, while being able to be turned, are not otherwise able to be moved in relation to the wheel) have to give the effect of squeezing and nipping the pipe element in the part where such squeezing is to take place, to such a degree that the pipe element is shut off completely fluid-tightly and no leaks are possible, whereas on the other side an overpowerful squeezing of the pipe element is not to take place, because this would be the cause of direct damage to the pipe element or at least make its working life shorter.Because of the great size of the backup wall in the circumferential direction and the even greater circumferential size of the support part, which is necessary to put the locking part of the ends of the support part, there is the shortcoming that the pipe element is acted upon at all times by at least two and (when one roller is coming off the pipe element) three rollers at a time touching the pipe element, something which for the given working life will be responsible not only for an increased squeezing effect and damage to the pipe element, so that its working life is decreased and furthermore the pumping function will not be quite as desired, because the amount of liquid pumped in the pocket in the pipe element between one squeezing roller and the next one is low in comparison.Because of this, to get a given rate of pumping, it is necessaryfortheturning speed of the support wheel with the rollers to be stepped up, this in turn increasing the rate of damage or wear caused by squeezing the pipe element and naturally decreasing its working life.

On the other hand, one further purpose of the pump of the present invention is that of making certain of such a nipping effect of the rollers on the flexible pipe element that, without being dependent on manufacturing tolerances, there is no overloading and damage to the flexible pipe element.

This purpose is effected by a preferred feature of the invention in which there is a support part united with said backup wall and a spring for loading said backup wall and moving ittowardsthe axis of turning of said wheel for causing a desired nipping of said pipe element. This further development of the pump may be used separately and is in fact to be looked at as a separate invention in its own right.

Because the support part may be moved in the direction of the supporting effect, its distance from the rollers may be changed and may take up different positions in relation thereto, dependent on the manufacturing tolerances of the pipe element.

Because of the spring force pushing the support part towards the axis of turning of the wheel and towards the nipping rollers, there is a softer nipping effect on the pipe element by the rollers forced against the backup wall. By selection and adjustment of the spring force of the support part it is possible in this way for the support part to be responsible for an exactly controlled force against the rollers as dependent upon any automatically produced position of the support part, such force on the pipe element being dependent on the one hand on the degree of stiffness of the material of the pipe element and the desired pumping head on the other so that the pipe is shut off liquid-tightly, while on the other hand no violent, sharp nipping forces will be possible.In view of this, it is possible to make certain that at all times only the desired, fully controlled nipping force, and no greater force, is produced under all conditions of operation.

If the support wall is curved along a greater angle than the one for example of 1800 round the outer edge of the roller supporting wheel, it is possible to have more than one support part, each designed to be moved in its general or average-out direction of support. However, as a general rule, one single support part with one backup wall will be all that is needed, the angle of the support wall at the outer edge of the wheel with the rollers being somewhat greaterthan the angle between adjacent of the regularly spaced rollers on the wheel, such angle of the backup wall being for example about 100 as measured at the middle point of the wheel. This makes certain that the pipe element will always be nipped liquid-tightly at at least one point so that there will be no chance of liquid to be pumped making its way backwards through the pipe element, while on the other hand, however, it will only be when one roller is coming up against one end of the backup wall and an other roller is coming off it that there will, for a short time, be two points at which the pipe element is nipped. For a given outer diameter and a given speed of turning of the support wheel, this will give the highest pumping rate. Furthermore, it will then only be necessary to have one single support part because on its moving away from the edge of the support wheel, the side parts of the backup wall will hardly be changed in their distance from the rollers.

Furthermore, on pulling back a single support part out of its working position into an opened position for working on the pump, it will at once be possible to get at the working part of the pipe element, so that it may be taken off the roller, looked at carefully and exchanged for a new one (if desired), as the support part may be moved back far enough generally completely putting an end to the nipping effect on the rollers.

A useful effect will be produced if the support part is locked in its pulled-back upkeep position for work in the pump so that it may be so moved quite simply by hand and will then keep in the opened position so that the person working on the pump will have his or her two hands free to get at the pipe element.

A more specially useful effect is produced if the locking effect is able to be overcome by an unlocking element so that the locked parts are freed, the unlocking element being positively moved into the unlocked position by moving a casing wall of the pump back into its closed position. This makes certain that in the running condition of the pump, that is to say generally when the casing is closed, the backup wall is pushed by the necessary spring force at all times towards the rollers to give the desired pumping function without any trouble conditions, whereas on the other hand undesired, chance turning on of the peristaltic pump with the support part still locked in the open position will not be possible.

Further details and useful effects of the invention will be seen from the account now to be given of one working example thereof as based on the figures.

Figure 1 is a plan view of a peristaltic pump of the present invention, its casing being marked in chained lines.

Figure 2 is a section on the line ll-ll of Figure 1.

As may be seen in the figures, the peristaltic pump has as its main working parts a flexible pipe element 1, support part 2 united with a backup wall 3 and a wheel 5 turned about an axis 4. At the outer edge of the wheel 5 there are four equally spaced rollers 6.

On turning the wheel 5 in the direction of arrow 7, the rollers 6 are forced one after the other against the curved working part 8 of the pipe element resting against the backup wall 3 so that, as the flexible pipe element is acted upon by one roller after the other, it is forced first by one roller 6 at a nip 9 moving with the roller 6 against the back up wall 3 so that the liquid in front of the nip 9 is peristaltically forced through the pipe element 1. The part 10, which in the present example isto be seen on the left, of pipe element 1 is joined up with an intake pipe for liquid, as for example liquid nutrient material, while the right hand end part 11 may be said to be the output connection of the pump.The end parts or connectons 10 and 11 are joined up by way of sleeves or the like with the casing 12 (marked in chained lines) of the peristaltic pump so that the pipe element 1 is regularly positioned at two ends of its working part 8 and kept in the desired place inside the peristaltic pump. The end parts 10 and 11 may be joined up with unions on the outer side of the casing, and which are not detailed in the present figures, forjoining up with connection pipes running to a liquid bottle on the one hand and the body of the patient on the other hand.

The backup wall 3, placed on the radially outer side of the rollers 6, is curved as part of a circle with an angle which, in the present working example, may be about 100 degrees, that is to say a little grea terthanthe angle of 90 degrees between the equally spaced rollers 6, this making certain that the pipe element 1 is nipped or squeezed to the start of the working part 8 shortly before the roller 6 at the end of the working part 8 has come clear of the backup wall 3 and so stopping its nipping effect on the pipe element.For this reason, it is not possible for any liquid to make its way backwards through the pipe element, while on the other hand, in normal operation the working part 8 of the pipe element is only nipped by one of the rollers 6 in its pumping position so that there are no undesired reactions between rollers acting on the pipe element at the same time.

The system for driving the wheel 5, which like the rollers 6 thereon may be made of synthetic resin, makes use of an electric motor 13 powered by batteries or the like not to be seen in the figure and which are placed in the space 14 on the two sides of the electric motor 13, with which they may be joined uo by way of a control circuit (not to be seen in the figure) for adjustment of the speed of the electric motor 13, as will be known to those trained in the art.

The electric motor 13, the support wheel 5 and the support part 2 are all supported on a plate 15, best made of metal, of U-like form. As will be seen more specially from figure 2, the flat middle part 16 of the plate 15 has a support sleeve 17 fixed to it, for example by screwing or by spot welding. This sleeve 17 has a plain bearing 18 therein for supporting a stub shaft 19 in which the wheel 5 is fixed. Wheel 5 has a great enough axial size to be so fixed to the stub shaft 19 that there is no danger of it being rocked on the shaft. In the present working example the wheel 5 is made up of two round plates 5a and 5b as walls thereof spaced by concentric spacer rings 5c and 5d, all made of synthetic resin.At their outer edges such plates 5a and 5b are joined up with pins 6a on which the rollers 6, made for example of hard rubber, are bearinged.

The top wing 20 in the figure of U-like plate 15 has the electric motor 13 fixed to its outer side, with the batteries (not figured) on the two sides of the electric motor. Wing 20 has a hole for the output shaft 13a of the electric motor 13 or a further piece of shaft fixed on such shaft, on which, on the inner side of wing 20, there is keyed a straight bevel pinion 21 meshing with straight bevel teeth 22 (which are radial with respect to the axis 4 of turning of the wheel 5) on the outer side of the inner plate 5b at its outer edge.By a simple gearing system, with straight teeth, troublefree transmission of power is possible with a high step-down ratio between pinion 21 and teeth 22 of for example 1:600 so that the electric motor 13 may be run at a high speed for which it is designed, without any complex gear system, such high running speed of the motor being stepped down to the very much lower speed of wheel 5. Because the diameter of the wheel 5 is so large compared to pinion 21, it may be possible to use a straighttoothed cylindrical pinion 21 with corresponding teeth on wheel 5. By supporting the drive shaft 13a of the electric motor 13, for example in the sleeve or the like in the wing 20, pinion 21 may be well supported without any bearing at its end furthest from the electric motor 13, so that there is no chance of the pinion 21 being pushed from sideto side.In fact, the design is such asto make quite certain thatthe desired driving force is transmitted by pinion 21 to the wheel 5. The axis of the driving shaft 13a and, for this reason, the main direction of the body of the electric motor, which is of a design generally on the market, and the general directions of the bodies of the batteries placed in space 14 on the two sides of the electric motor 13, are normal to the axis 4 of tuming of wheel 5, that is to say parallel to the general direction of its body. For this reason, all the larger parts of the system are placed parallel to each other and even if the diameter of the wheel 5 is very large in site, as will be needed for smooth, quiet running at a low speed, the peristaltic pump will be very thin, as will be seen from the figures.The breadth of the peristaltic pump from side to side will be generally dependent on the diameter of the wheel 5 together with the thickness of the pipe element 1 so that even although the wheel 5 is, as desired, as large in diameter as possible, the peristaltic pump will not be unnecessarily broad. Furthermore, the present design, as is to be seen from the figure, makes it possible for the peristaltic pump to have a flat rectangular casing 12 with very much the right desired propeties of a pump to be taken around bythe patientwith him, it being fixed for example on his belt or the like, resting flat against his body.

Support part 2, having on its inner side the part circular backup wall 3, may be moved in the support direction marked bythetwo-headed arrow 23 and is fixed to guide pins 24 running in the lower wing 25 of U-like part 15 so that motion of support part2 in the direction of arrow 23, that is to say generally normal to the axis 4 of turning of the wheel 5, is possible.For nipping the pipe element 1 atthe squeezing point9 where one of the rollers 6 is pushed against the pipe element, support part2 is acted upon by springs 26 pushing it towards the axis 4 turning of wheel 5 with such a force that the desired nipping force, necessary for stopping free flowthrough the pipe element, takes effect on pipe element 1 in the working parts atthe rollers 6, taking into accountthe stiffness of the material of the pipe element 1 and the pumping head force. The pipe element 1 may well be made of silicone resin with an inner diameter of 3 to 4 mm and a wall thickness of 1 to 1.1 mm so that, given a force of spring 26 acting on the support part 2 between roughly 22 Newtons and 4 Newtons a pumping head of about 0.5 bar or somewhat more may be produced.At a speed of turning of wheel 5 between 25 and 240 rph, the upper limit of the pump ing rate will be 250 much, high enough for all purposes and more specially enteral nutrition or feeding. If desired, the pumping rate may be decreased to about one tenth of this rate. Taking into account the step-down ratio of 1:600 between the pinion 21 and the teeth 22, in this range of speed adjustment motor speeds between 180 and 250 rpm will come into question so that as the electric motor 13 any desired mass produced DC motor may be used.In view of the low running speed of wheel 5 with a diameter of at least 50 and in the present example about 70 mm or even more, the noise level will be very low, that is to say about 20 dB or even less so that in fact the only noise, generally speaking, will be soft purring of the electric motor 13 which furthermore will seem to be quieter because of casing 12.

Casing 12 is made in two parts, that isto say atop casing part 12a and a lower casing part 12b which have grip hollows 12c so that the two parts may be pulled clear of each other. On taking off the housing part 12b, which is lower down in the figure, the working parts of pipe element 1 will be uncovered and may be got at from the outside. When the support part 2 is pushed against the force springs 26 towards lowerwing 25 of U-like part 15, the pipe elementwill no longer be nipped by the roller 6 at the position 9 at which the roller is placed, so that the pipe element 1 will be resting more or less completely loosely against the inner side of the backup wall 3.In this respect, the amount of possible motion of support part2 (along the direction marked bythetwoheaded arrow 23) against the force of springs 26 is so great that pipe element 1 may be moved com pletelyclearofthe nipping roller at 9; in fact, the amount of motion of the support part is somewhat greater than the inner diameter of the pipe element 1.

For trouble-free attention to the pipe element, for example for putting in a new piece of pipe or some other purpose with the support part 2 pulled back, the same may be locked in its pulled-back position for working on the pump and in the present working example it will be seen that a spring tonguepiece 27 is fixed on wing 25, tonguepiece 27 having a hook 28 orthe like and having the tendency of springing into a position in which hook 28 comes into position to the back of a stop face 29 on support part2 for lock- ing the support part in the pulled-back position for making adjustments or doing some form of upkeep work on the pump.If the springing tonguepiece 27 is moved against its spring force, the hook28 will be cleared from stop face 29 so thatthe support part 2 may be moved by the springs 26 back towards the axis 4 of turning of the wheel 5 into the working position of the pump parts. For moving the hook free of the stop face 29, there is an unlocking part 30 in the form of a pin running through support part 2, which may be pushed in from the front side of the support part2, its opposite end then pushing the springing tonguepiece27 clearofthe stop face. For stopping operation of the peristaltic pump while the support part 2 is in the pulled-back position for adjustment of the pump, in which case there would be no pumping effect, the front end 30a of the unlocking part 30 is so placed that, when the casing is shut, it is forced inwards by the casing wall 12d (in the present example is part of the lower casing part 12b) and pushed inwards. Because of this, the springing tonguepiece 27 is forced back into its position freeing the stop face 29. For stopping the edge of casing wall 12d jamming againstthe end of unlocking part30 on shutting the casing, the front end 30a of unlocking part 30 may be sloped at30b or speciallyformed in some otherway.

For this reason, when the casing part 12b is pulled off, the working part 8 of the pipe element 1 will be uncovered and in this position the support part2 may be pulled back into the adjustment position and locked automatically by the hook 28 hooking onto the stop face 29, the springing tonguepiece 27 then forcing the unlocking part 30 to the left (in view of figure 2) so that its front end 30a is sticking out far enough; that isto say when the lower casing part 12b is put on again, the unlocking part 30 will be forced back again because of the casing wall 12d acting on the sloping face 30b of the said unlocking part 30, the springing tonguepiece 27 then being bent back and then kept in position, the stop face 29 atthesametime being let go of by hook28.In this operation position the support part 2 and, for this reason, the backup wall 3 will have the effect of forcing the pipe element 1 against the rollers 6 and at the nip point 9, without being dependent on manufacturing tolerances or the like. The force of the springs 26 in this respect may be changed as desired. The design makes it possible, in a simple way, on the one hand to seethatthere are no overgreat nipping or squeezing forces on the pipe element 1 at the nip point 9 while on the other hand, however, the desired force or pressure in on hand all the time to make certain that the pipe element 1 is shut com pletelybythe nipping effectatthe nip 9.

Taking a general view, it will be seen that the invention makes possible a peristaltic or roller pump which has quiet running properties, a low weight and a low volume so that patients, for example, undergoing enteral nutrition, may take it around with them all the time without in any way getting in their way causing any undesired effects in other respects. One form of the peristaltic pump with the pumping rates etc. as noted in the present specification has a size of the casing 12 measuring 146 mm x 64 mm x 35 mm, it keeping to all conditions with respectto exact rate control of the nutrient liquid as dependent on the speed of turning.

Claims (13)

1. A peristaltic pump for medical purposes having a flexible pipe element, a part-circular backup wall having an inwardly curved face for supporting said pipe element, a wheel with rollers for rolling said pipe element and nipping it against said wall at a point moving along said pipe element giving a peristaltic pumping effect, and an electric motor for driving said wheel, characterized in that the wheel has an axis of turning normal to the axis of turning of said electric motor.

2. A peristaltic pump as claimed in claim 1, characterized in that said wheel has gear teeth at an outer edge thereof, the electric motor having a pinion for driving said teeth with a step-down ratio of morethan 1:100.

3. A peristaltic pump as claimed in claim 2, characterized in that said step-down ratio is more than 1:500.

4. A peristaltic pump as claimed in claim 2, characterized in that the teeth on said wheel are in a radial plane with respect to said axis of roation of said wheel, said pinion being on the axis of the electric motor.

5. A peristaltic pump as claimed in claim 4, characterized in that said pinion is directly keyed on a shaft of said electric motor.

6. A peristaltic pump as claimed in anyone of claims 1 to 5, the electric motor is battery driven and the batteries for driving the motor are placed to the sides of said electric motor so as to be parallel thereto.

7. A peristaltic pump as claimed in any one of claims 1 to 6, characterized in that the support wall is placed on at least one support part, which is guided for motion in the support direction and which is loaded towards the axis of turning of the wheel with a spring force producing the desired nipping of the pipe element.

8. A peristaltic pump as claimed in claim 7 characterized in that said wall is part of a support, said support part being able to be moved back against said spring loading system through a distance which is greaterthan an inner diameter of said pipe element, forthe purpose of upkeep of parts of said pump.

9. A peristaltic pump as claimed in claim 8, characterized in that it has a locking system for locking said support part in said upkeep position.

10. A peristaltic pump as claimed in claim 9, characterized by a casing having a casing wall for covering said support part on operation of said pump and an unlocking part designed to be acted upon and moved by said casing wall for putting said locking system out of operation.

11. A peristaltic pump as claimed in anyone of claims 1 to 10, characterized in that the angle of the part-circularform of said backup wall as measured at the axis of said wheel, is somewhat greater than the angle between one roller and the next one on said wheel.

12. A peristaltic pump as claimed in claim 2 or claim 2 and anyone of claims 3 to 11, characterized by a stub shaft on said wheel, a shaped bracket with a middle part on which said stub shaft is bearinged, a limb on said U-like part supporting said electric motor, the pinion being on an inner side of said limb and a second limb at an opposite end of said U-like part for supporting said backup wall movingly thereon.

13. A peristaltic pump as claimed in claim 1, substantially as described above with reference to and as illustrated in the accompanying drawings.