NZ194940A

NZ194940A - Reciprocating pump reversing mechanism

Info

Publication number: NZ194940A
Application number: NZ194940A
Authority: NZ
Inventors: W S Credle Jr
Original assignee: Coca Cola Co
Priority date: 1979-09-21
Filing date: 1980-09-12
Publication date: 1984-03-16
Also published as: NL8005213A; BR8006025A; GB2060086A; NL182742C; AR224781A1; JPS5681283A; AU525981B2; GB2060086B; ES8105833A1; JPS595785U; ES495056A0; CA1155711A; ZA805694B; DE3035516A1; MX151144A; PH18178A; IT8024802A0; KR850000419B1; FR2465905A1; AU6250080A

Description

<div class="application article clearfix" id="description"> 1 > M Priorfiy D3te{s): }O.Q <k0 Cornpi&t© Specification Fiied: . ■ . I1. •« Class: JI■ ■ Publication Date: ..*16 WAR .1.9.04 1 #o, JeurnpJ, No: $f?. , Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION RecvifoccAi^ PUMP,.REVERSING MECHANISM TW«_Vor £/WE THE COCA-COLA COMPANY, a corporation organized and existing under the laws of the State of Delaware, U.S.A. of 310 North Avenue, Atlanta, Georgia 30313, United States of America, hereby declare the invention, for which ^/we pray that a patent may be granted to jfltff/us, and the method by which it is to be performed, to be particularly described in and by the following statement - 1 - r '.1 z' o BACKGROUND OF THE INVENTION This invention relates to a pneumatically operated diaphragm punp utilized in a Post-mix beverage syrup dispensing system and more specifically to a reciprocating pump including a spring actuated reversing means for reversing the direction of a reciprocating pump at the end of its respective strokes. Diaphragm pumps are widely used particularly for pumping liquid solutions and highly viscous materials and are frequently 0 used under conditions such that the viscosity of the fluid being pumped, the head of the suction side of the pump and the back pressure on the pump discharge may all vary as conditions under which the pump is operating vary. The speed of such pumps has generally been controlled by inserting an adjustable valve in the 5 air line leading to the pump. However, this approach requires that the operation of the pump be kept under continuous observation and the valve adjusted to suit varying conditions, otherwise the speed of the pump will vary substantially depending upon the conditions of operation. For example, if the back pressure on 0 the pump should increase or decrease for any particular reason, or if the viscosity of the liquid being pumped should vary, then the speed of operation and the quantity of liquid being pumped per unit of time will accordingly be affected. Therefore, it is highly desirable that the pump be controlled such that it operates S at a substantially constant speed under varying conditions. Furthermore, it is essential that the entire pumping cycle be completed so as to ensure continuous delivery of the medium being pumped at a constant consistency or concentration. In order to ensure the latter, means have been suggested such as disclosed in 0 U.S. Patent 4,008,984 wherein opposed coil springs are provided -2- K> CO i— U 1 ! o \ oo • , J (N f for assisting the respective valve member in the completion of its pumping cycle. The coil compression springs of identical force under the pressurized gas system assist in completion of the pumping cycle first in one direction, and then by asserting a positive reversing effect when either of the springs becomes fully compressed. Although providing a reversing mechanism for the double acting pump disclosed there are inherent disadvantages with such a system. For example, if for some reason the pressurized system is effected in such a way that a back pressure is created or established so as to inhibit or reverse the pumping cycle before it is completed, there is no means for overcoming the undesirable effect, and the fully compressed state of the spring is not reached. Thus, it is possible that the pumping cycle could be reversed regardless of the presence of the compression springs, before the cycle is completed, thus effecting the efficiency if not the complete purpose of the reciprocating pump. It is, therefore, an object of the present invention to provide a reciprocating diaphragm pump for delivering, under constant pressure, syrup to a Post-mix beverage dispensing system which will overcome the above noted disadvantages. According to the present invention a reciprocating pump apparatus including in combination, a housing having/laterally spaced chambers with diaphragm members therein dividing each of said chambers into a driving section and a discharge section, said diaphragm members being interconnected by a common shaft, a protrusion on said common shaft at approximately the mid-point input and output of the longitudinal dimension thereof,/manifold means in said housing for interconnecting said discharge sections of said chambers with fluid inlet and outlet ports, respectively, inlet and outlet valves in said ports for controlling the flow of fluid to be pumped to and from said discharge sections with respect to said manifold means, said discharge sections having end walls parallel to major surfaces of said diaphragm members and walls perpendicular thereto, distribution means for -3- directing driving fluid alternately to a selected one of said driving sections defined by said diaphragms in said lateral chambers, said distribution means including control valve means coupled to the source of driving fluid, a valve actuating member mounted on said shaft for sliding movement thereon between first and second positions in response to engagement by said protrusion, said valve actuating member constraining said control valve means to alternately direct said driving fluid to the respective driving sections in said first and second positions of said actuating member, and snap-acting means for precluding the stopping of said valve actuating member between said first and second positions, the improvement comprising: said control valve means including a housing with distal ends symmetrically mounted with respect to the midpoint between said laterally spaced chambers, a reciprocable spool valve element within said housing having opposite ends extending through said distal ends of said housing and first and second positions for alternately directing said driving fluid to said respective discharge sections in response to actuation forces applied to said opposite ends; said actuator member having spaced actuator arms extending therefrom for alternately engaging respective ones , of said opposite ends of said spool valve element to apply said actuation forces thereto; and said snap-acting means including a pair of opposed compression springs, each of said springs being operatively associated with a /support pin, one end of each of said support pins being pivotally mounted at fixed points with respect to said pump housing at approximately the mid-point between said laterally spaced chambers, the other end of each of said support pins being pivotally coupled to said actuator member at the mid-point between said actuator arms, said support pins and compression springs thereon being disposed for movement in a common plane on opposite sides of an axis parallel to a ¥ longitudinal axis of said shaft, whereby said compression springs exert equal and opposite forces on said valve actuating member in directions transverse to said axis throughout all positions of movement of said actuating member on said shaft. Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration only since various changes and modifications within the scope of the invention as setforth in the appended claims will become apparent to those skilled in the art. * Any such changes and modifications should be considered to be within the scope of this invention. GENERAL DESCRIPTION OF THE INVENTION The foregoing objects and others are accomplished in NX PATENT OFFICE 20 OCT 1983 ✓ \ ft 10 15 20 25 accordance with the present invention generally speaking by providing a pumping device comprising a pair of flexible diaphragms mounted on the respective ends of a common shaft. The outer surface of the diaphragms are in contact with the liquid to be dispensed by the system, more particularly syrup for a Post-mix beverage dispensing system. The chamber within the pump housing contains an inner wall in which passages are provided for directing compressed air, introduced into the reciprocating pump, to the surfaces of the diaphragms. The flow of air is controlled by a reversing valve adapted so as to redirect the flow of compressed air to the respective diaphragm at the completion of each stroke of the pump in a cyclic manner. A valve actuating member or yoke is provided which engages the shaft within the inner chamber of the pump housing and travels with the pumping action of the shaft. The yoke is designed so as to engage the reversing valve during the terminal phase of the pumping stroke thus activating the valve and reversing the piston action of the pump. To complete the pump reversing system, a snap-acting spring actuating means interconnected with the yoke of the shaft, is centered within the inner chamber of the housing of the pump, pivotably mounted beneath the shaft connecting the diaphragms. The valve is provided with 0-rings positioned within the valve body with respect to the air passages of the valve such that during the first half of the reciprocating cycle pressurized gas is introduced through the respective passage ways and directed to the air chamber of one of the diaphragms. At the same time a passage is provided for exhaust gases to be released from the air chamber of the remaining diaphragm. Upon interaction with the shaft yoke and the spring mounted actuating means the relationship of the valve openings to the pressurized -M-6 n n 'i o .* o i y / 10 15 20 25 30 gas acting on the surface of the respective diaphragm is changed at the completion of the pumping stroke so as to reverse the action of the pump. The snap-action mechanism provided precludes the sticking of the pneumatic reversing system in an intermediate position. In operation, pressurized gas is introduced through a passage way into a valve member and is directed via a passageway within the inner wall of the pump housing to the air chamber of one of the diaphragms within the pump. As the piston action of the dia phragm forces syrup from the diaphragm chamber out the appropriate passage to the dispensing outlet, movement of the shaft also moves the remaining diaphragm in a non-pressurizing direction. This same shaft movement also engages the shaft yoke. As the shaft yoke moves—it initiates the pivotal action of a pair of snap-acting compression springs which, prior to rotating off center, are pushing against each other. As the springs rotate off-center they uncoil and push the shaft and yoke along in the direction of the established movement. The action of the spring mechanism ensures that the movement of the diaphragm, initiated by the air pressure, is taken to completion by the snap action of the compression springs while at the same time reversing the flow of pressurized air within the valve member. This procedure is then repeated as long as the dispensing outlet is open and the syrup is being dispensed as a pressurized stream. When the dispensing outlet is closed sufficient back pressure is exerted on the diaphragms to prevent shaft movement. It has been determined in the course of the present invention that a reciprocating diaphragm pump for syrup in a Post-mix beverage dispensing system can be provided such that the liquid can be delivered under controlled pressure conditions in a -4-1 I > reliable manner. A reversing valve is provided which includes a pair of compression springs bearing one on the other so as not to apply pressure of the bearing surfaces on the pump shaft. As the pistons of the diaphragm pump are driven by the pressurized gas there is always the possibility that a back pressure or some othet malfunction might occur which could result in a premature reversing of the pump cycle before it is completed thus interrupting delivery of the necessary syrup at the dispensing outlet. Upon the introduction of the spring actuated means of the present invention, this premature cycle reversal is eliminated by the snap action resulting from the specific positioning and interrelationship of the compression springs within the valve reversing system. The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only and thus are not limitative of the present invention. Figure 1 is a cross-sectional view of the pump of the present invention representing the initial position of a pressure stroke in the direction indicated; Figure 1A is a top view of the pump of Figure 1, illustrating the details of the fluid input and output manifolds and the inlet and outlet valves of the pump of the present invention; Figures 2A and 2B are partial side and bottom views respective ly, of the pump of Figure 1 illustrating the spring reversing system of the present invention at the snap-over center toward the right; Figures 3A and 3B are partial side and bottom views respective ly, of the pump of Figure 1, illustrating the spring reversing mechanism of the present invention immediately after the snap-over BRIEF DESCRIPTION OF THE DRAWINGS -X-<6 r> o i94940 position of Figures 2A, 2B, which causes the pump shaft to reverse directions and move to the left; Figure 4 is a cross-sectional view of the reversing valve of the present invention in the position that it occupies when the pump shaft of Figure 1 is driven to the right; Figure 5 is a cross-sectional view of the reversing valve of the present invention in the position that it occupies when the pump shaft of Figure 1 is driven to the left; Figure 6 is an exploded view illustrating the details of how the yoke of the present invention is mounted on the pump shaft; Referring now to Figures 1 and 1A, there is seen a cross-sectional side and top view, respectively, of the reciprocating pump of the present invention, comprising a housing 11 having an input manifold 12A and an output manifold 12B in its top wall for carrying the syrup to be pumped from the inlet SI through the respective chambers discussed below to the pump outlet SO. Within an inner chamber 13 of the pump is positioned a shaft 14 interconnecting diaphragms 16A and 16B. An actuating member or yoke 17 with protrusions or arms 17A is slidably supported on the shaft 14 by the longitudinal bore 17B, Figure 6, passing therethrough. A reversing valve 40 is attached to the inner wall 21 of housing 11 within the inner chamber 13 of the pump. The shaft 14 is press-fit with a pin 25, which and Figure 7 is a partial view illustrating another embodiment of the pump~diaphragm of -the present invention. DETAILED DESCRIPTION OF THE DRAWINGS -X-9 3Q JUWVJ83- 194940 upon operation of the pump, travels with the movement of the shaft predetermined distance before engaging an end of slot 26 provided in the yoke 17. Shaft 14 is mounted for sliding movement in O-ring seals or at its respective ends. Pivotally mounted beneath the yoke and interconnected therewith is a spring actuating member 27, (Figures 2B, 3B) within the housing chamber 13. The reversing effect of the valve 40 is facilitated as a result of the interrelationship between the actuating yoke member 17 and the spring actuating member 27 and alternately directs pressurized gas introduced through passageway 22 to the respective air chambers ISA and 1SB, through passageways 23 and 24, to apply pressure to the respective diaphragms 16A and 16B. The reversing valve 40 compxises a valve body 41 and spool element 42 with 0-rings 43. A more complete discussion of the operation of the reversing valve can be found below with respect to Figures 2A, 2B, 3A, 3B, 4, and 5. Each diaphragm of the pump is constructed of a flexible material, such as rubber, secured to the inner walls of the pump housing at positions 20. In a preferred embodiment of the present invention, the diaphragms further include a metal piston on the outer face of the respective diaphragm and a metal retaining cap on the inner surface of the respective diaphragm, as illustrated in Figure 7 to be discussed hereinafter. The pumping cycle of the pump of the present invention and the flow of fluid therethrough can be best illustrated by reference to Figure 1A. Fluid to be pumped is introduced through an inlet SI to input manifold 12A which extends across the top of the pump and communicates with fluid chambers 28 and 29 via normally closed 10 30 jvmvjss r> I 94940 check valves 31L, 31R. When the fluid pressure in input manifold 12A exceeds the pressure in either chamber 28 or 29, check valves 31L, 31R open. Since the pump of the present invention is a reciprocating pump, the fluid pressures in chambers 28, 29 are always in the opposite state. That is, if the pump shaft in Figure 1A is moving to the right chamber 28 has a higher fluid pressure than manifold 12A, and chamber 29 has a lower fluid pressure than manifold 12A. Under these conditions check valve 31L opens introducing fluid into chamber 29 and check valve 31R is closed. Thus, as the pump cycle^ check valves 31L, 31R alternately open and close. Outlet check valves 32L, 32R, disposed in an output manifold 12B, function in substantially the same manner. That is, when the pressure output manifold 12B is less than the pressure in one of the respective chambers 28, 29 the check valve in that chamber opens, discharging fluid therefrom to pump outlet SO. In the above example, with the pump shaft 14 moving to the right, the pressure in chamber 28 is high, thus opening valve 32R and per-miting the fluid therein to discharge via manifold 12B and pump outlet SO. The check valves 31L, 31R, 32L, 32R are substantially identical except for the respective orientations thereof. Each is formed from rubber and'includes a central stem fixedly mounted in the pump wall, and a disc-shaped seat B, which normally seats on fluid ports C. When biased by fluid pressure to open, disc-shaped seat B flexes away from parts C, permitting fluid to pass therethrough. The above-described check valves are disposed at the highest -US-ll 30JUNVW& o positions of chambers 28, 29 to preclude the formation of air pockets which could be sucked out through pump outlet SO, resulting in an uneven flow of fluid. Figure 6 illustrates the details of actuating member or yoke 17, which is mounted for movement on shaft 14. Yoke 17 includes a pair of upstanding arms 17A described hereinbefore for engaging the valve 40 and switching the same from one state to another. A longitudinal bore 17B is provided in yoke 17 for receiving pump shaft 14. After pump shaft 14 is inserted in bore 17B, pin 25, described hereinbefore is press-fitbedinto aperature 14A in shaft 14. A bottom plate 17C is suitably attached to the bottom of yoke 17, thus supporting a pair of pins 39 therein. As will be discussed hereinafter pins 39 support one pair of ends of spring members of the snap acting mechanism illustrated in Figures 2B and 3B. Referring now to Figure 2A, 2B, there is seen in cross-section the pump mechanism set forth in Figure 1 representing a pressure stroke of the pump in the direction indicated at the point of engagement of the pin 25 of shaft 14 with an end of slot 26 in the shaft yoke 17. At this instant the yoke is picked up by pin 25 and begins to move with the shaft and the spring actuating member 27, connected to the yoke, begins to pass over center. The diaphragm 16bapplies pressure to the liquid present in the chamber 28, which is released via check valve 32R into passageway 12b and directed out through the pump outlet SO to the respective discharge stations. Figures 2B, 3B represent the postion of the diaphragm, shaft and yoke at the completion of the stroke. As the reversing mechanism, generally indicated 27, moves over center •yC-IX 30 jliHWW r> there is produced a snap action effect which thrusts one arm 17 A of the yoke against the protruding end of the spool 42 thus changing immediately the positions of the O-rings of the valve so as to suddenly reverse the flow of pressurized air through the valve 40 at the completion of the stroke, and reverse the piston action of the pump. Figures 2B and 3B illustrate the details of the spring reversing mechanism 27. The spring reversing mechanism in one embodiment comprises a coil spring 36 wrapped about a pin 37 and pivotally attached by way of pin 38 to the housing and pin 39 to the yoke 17. Upon engagement by the pump shaft, the yoke 17 will move in the direction of the stroke of the pump which in turn rotates pins 38 over center about pins 38 such that the springs 36 take over and push the yoke in the direction of the established movement at a speed faster than the shaft movement, until the yoke hits against the spool 42 of the valve mechanism so as to reverse the direction of the flow of pressurized air within the system and establish the piston action of the pump in the opposite direction. The position of the compression springs and yoke at the ends of the stroke are represented in Figure 3B. The presence of the pins 37 within the coil spring 36 prevents the spring member from buckling during the movement of the piston during the operation of the pump. Alternately, torsion springs 36T in phantom may be substituted for the coil springs herein illustrated to provide the snap-acting actuating means of the present inven- ' tion. The yoke 17 slides or is pushed along by the shaft and spring mechanism 27 of the pump first in one direction then in a reverse direction according to the reversing action of the valve -rl- 1$ 30 JUm983 !i r> l94940 40. In Figures 4 and 5 there is illustrated a simplified enlarged cross-sectional view of the reversing valve 40 of the present invention which is represented herein as a spool valve comprising a valve body 41, the spool 42 having three 0-rings 43 intermittently positioned thereon within the valve cavity 44. Within the upper area of the valve body are located air passages 45 coupled to passage 22 of Figure 1, for introducing the pressurized gas into the valve cavity 44, and 46 and 47 coupled to passages 24,23 of Figure 1, for directing air through the valve to the surface of the respective diaphragms of the pump. The valve 40 herein represented shows air under pressure being introduced to the valve cavity 44 through passageway 45 such that during the first half of the reciprocating cycle -the air is directed to the respective air chamber 15B, through passageway 46 and passageway 24 (See Figure 1), while at the same time remaining passageway 47 provides for exhaust gases to be released as illustrated from the air chamber of the remaining or opposite diaphragm air chamber 15A. Upon contact by the left protruding end of the spool 42 with the yoke 17 as discussed above, the spool 42 is thrust to the right such that at the end of the pumping action the 0-rings 43 shift their position as illustrated in Figure 5, and the pressurized gas is now directed in the opposite direction so as to be introduced into the air chamber 15A of the diaphragm 16A, thus driving the pump in the opposite direction. In this position, the right end of the spool now projects from the valve cavity 44. and awaits to be engaged by an arm 1'7A of the shaft yoke in the reverse action of the piston. - ys- <4- i94940 In operation the valve 40 alternates the air flow through the respective passages 23, 24 to the air chambers 15A, 15B of the diaphragms 16A, 16B. The compression springs 36 or 36T interconnected to the yoke continuously urge the shaft of the diaphragm pump first in one direction then the other, responsive to the location of the yoke 17 along the shaft. The pressurized air is introduced into the air chambers 15A, 15B behind the respective diaphragms 16A, 16B and drives the diaphragms so as to discharge the liquid from the diaphragm chambers. As stated above, the yoke 17 on the shaft 14 initially moves in coniunction with the movement of the shaft upon engagement of an end of slot 26 with the pin 25 in shaft 14. The compression springs 36 or 36T, which at the time of engagement are pushing against each other, with substantially no net force in a direction transverse to the pump shaft, pivot over center and apolv a further driving force to the yoke which is then caused to move Quickly by the snap-action of the springs 36 to seat the projecting portions or arms 17A of the yoke 17 against the protruding spool 42 of the valve 41. This changes the positions of the 0-rings within the valve body and reverses the flow of pressurized air therein thus completing the first half of the cycle of the diaphragm pump. The continuous] introduction of pressurized air into the valve 40 initiates the pumping action of the shaft mounted piston in the opposite direction, first compressing the spirngs 36 or 36T and then repeating the action described above in the opposite direction, the compres-j sed springs not pushing in the opposite direction. The spring reversing mechanism ensures that the" movement of either of the -3rt-15 '194940 diaphragms initiated by the air pressure, is completed thus preventing premature reversal of the pumpinc stroke or sticking of the valve 40 in a central position. Referring now to Figure 7, there is seen in cross-section a pump construction similar to that discussed above with respect to Ficures 1 and 1A, except with respect to the structure of diaphragms 16A, 16B. The diaphragms 16A and 16B further include cup-shaped metal plates 52 on the outer face of the respective diaphragm surface and cup-shaped retaining cap 54 on the inner surface of the respective diaphragms. This configuration eliminates the formation of crevices in the flexible diaphragm. materi, Preferably, the pump housing is constructed of a molded plasties/ as herein represented in Figure 1, such that the valves are mounted through the pump and all the lines or passageways run inside the plastics housing. This construction eliminates unnecessary joints and external lines which contributes to a more reliabli system. As is seen in Figure 1, the inner wall of the housing comprises one continuous member which surrounds the pump reversing system components. The outer walls of the housing 11 are also material fabricated of molded plastics^hicft provides for an overall more desirable construction of the diaphragm pump of the present invention. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention and all such modifications as would be obvious to one skilled in the art are intended "to be included within the scope of the following claims. -y$-IG </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 1 O A Q A n I / i / 'i u WHAT WE CLAIM IS:

1. A reciprocating pump apparatus including in combination, a housing having/faterally spaced chambers with diaphragm members therein dividing each of said chambers into a driving section and a discharge section, said diaphragm members being interconnected by a common shaft, a protrusion on said common shaft at approximately the mid-point of the input and output longitudinal dimension thereof,/ltianifold means in said housing for interconnecting said discharge sections of said chambers with fluid inlet and outlet ports, respectively, inlet and outlet valves in said ports for controlling the flow of fluid to be pumped to and from said discharge sections with respect to said manifold means, said discharge sections having end walls parallel to major surfaces of said diaphragm members and walls perpendicular thereto, distribution means for directing driving fluid alternately to a selected one of said driving sections defined by said diaphragms in said lateral chambers, said distribution means including control valve means coupled to the source of driving fluid, a valve actuating member mounted on said shaft for sliding movement thereon between first and second positions in response to engagement by said protrusion, said valve actuating member constraining said control valve means to alternately direct said driving fluid to the respective driving sections in said first and second positions of said actuating member, and snap-acting means for precluding the stopping of said valvfe actuating member between said first and second positions, the improvement comprising: -17- N.Z. PATENT OFFICE 200CTI983 •; o a o .1 n I / t y "i V said control valve means including a housing with distal ends symmetrically mounted with respect to the midpoint between said laterally spaced chambers, a reciprocable spool valve element within said housing having opposite ends extending through said distal ends of said housing and first and second positions for alternately directing said driving fluid to said respective discharge sections in response to actuation forces applied to said opposite ends; said actuator member having spaced actuator arms extending therefrom for alternately engaging respective ones of said opposite ends of said spool valve element to apply said actuation forces thereto; and said snap-acting means including a pair of opposed compression springs, each of said springs being operatively associated with a /feupport pin, one end of each of said support pins being pivotally mounted at fixed points with respect to said pump housing at approximately the midpoint between said laterally spaced chambers, the other end of each of said support pins being pivotally coupled to said actuator member at the midpoint between said actuator arms, said support pins and compression springs thereon being disposed for movement in a common plane on opposite sides of an axis parallel to a longitudinal axis of said shaft, whereby said compression springs exert equal and opposite forces on said valve actuating member in directions transverse to said axis throughout all positions of movement of said actuating member on said shaft. -18- N.Z. PATENT OFFICE 20 OCT 1983 RECEIVED 1 O /i o ' r> l y -1 .■ •- i i

2. A reciprocating pump apparatus as claimed in claim 1, wherein said compression springs are coil springs concentrically disposed around said support pins.

3. A reciprocating pump apparatus as claimed in claim 1, wherein said compression springs are torsion springs.

4. A reciprocating pump apparatus arranged, constructed and adapted to operate substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings. N.Z. PATENT OFFICE 2 0 OCT 1983 HcCEiVED </div>