US3771087A - Circuit breaker, trip mechanism and method for manufacturing same - Google Patents
Circuit breaker, trip mechanism and method for manufacturing same Download PDFInfo
- Publication number
- US3771087A US3771087A US00159930A US3771087DA US3771087A US 3771087 A US3771087 A US 3771087A US 00159930 A US00159930 A US 00159930A US 3771087D A US3771087D A US 3771087DA US 3771087 A US3771087 A US 3771087A
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- US
- United States
- Prior art keywords
- trip mechanism
- housing
- plunger
- circuit breaker
- breaker
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H73/00—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism
- H01H73/60—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism cartridge type, e.g. screw-in cartridge
- H01H73/62—Protective overload circuit-breaking switches in which excess current opens the contacts by automatic release of mechanical energy stored by previous operation of a hand reset mechanism cartridge type, e.g. screw-in cartridge having only electrothermal release
Definitions
- ABSTRACT This is a miniature circuit breaker which is wholly contained within a screw-type envelope for a type S fuse.
- the breaker trip mechanism is of the type which has a resetting plunger, and a current sensing device which moves relative to the plunger. In order to limit the travel of the current sensing device under trip conditions, stop shoulders are formed on the body of the plunger.
- the current sensing device takes the form of a bimetallic member formed with a leading latch edge and a trailing edge.
- the circuit breaker housing is of one-piece construction, and has an open end through which the trip mechanism is inserted.
- the trip mechanism incorporates a plungerbiasing coil spring at the bottom of the trip mechanism. In order to retain the compression spring in assembly with the plunger while the trip mechanism is dropped into the open end of the breaker housing, the spring is frictionally received within a recess formed at the bottom of the plunger.
- the current sensing device includes a pair of bimetallic pincers embracing the plunger, and one of these pincers is formed with a through out in order to divert all of the current to the opposed pincer, at least under trip conditions.
- One of the external electrodes of the breaker is formed of inexpensive round wire stock.
- the bimetallic element has leading and trailing edges.
- the leading edge is intended to have latching engagement with a latch member on the circuit breaker plunger, but the trailing edge is not intended to engage with the latch member. Nevertheless, the trailing edge often doescatch the latch member,
- This invention contemplates a circuit breaker having a trip mechanism of the general type disclosed in the Ingwersen patents above. But in order to limit the trip movement of the mechanism, and thereby keep tension on the trip springs so that they remain in assembly, shoulders are provided on the plunger body which engage the edges of the bimetal elementto limit its travel under trip conditions. Also, a trailing edge of the bimetal is formed with a tang which projects across. the latch member and therby prevents undesirable engagement or hang-up during resetting. The bimetal limiting position defined by the stop shoulders mentioned above are so chosen that the aforesaid tang cannot move past the latching member.
- the circuit breaker of this invention may be mounted within a screw-threaded fuse envelope of the S type.
- the housing has a cover member which is provided with one or more bosses and/or vent holes at opposite ends of the breaker, so as to avoid the exploding, cracking. and charting effects which have afflicted previous type S circuit breaker devices under severe fault conditions.
- This inbalance may be achieved by forming a through cut in one of the bimetallic elements. Such a cut is effective, at least under trip conditions, to divert all of the fault current to the other element.
- a circularly shaped external electrode of the circuit breaker is easily and economically formed from wire stock of round cross-section, which is less expensive than stamping from flat sheet stock, especially when one considers the waste entailed in stamping a circular configuration defining a central disc which is discarded.
- the wire stock is bent into the required circular configuration, without waste, and formed with resilient axially projecting bights to define resilient electrical contacts.
- the wire stock is stamped flat at least at one location.
- FIG. 1 is an exploded perspective view of an S type fuse envelope circuit breaker in accordance with this invention.
- FIG. 2 is a top plan view of the empty screw-base housing of the circuit breaker.
- FIG. 3 is an exploded perspective view of the same empty housing and the cover thereof, illustrating the manner in which the two are assembled in manufacturing a circuit breaker according to this invention.
- FIG. 4 is a bottom plan view of the circuit breaker of FIG. 1, fully assembled.
- FIG. 5 is an elevational view of the same circuit breaker.
- FIG. 6 is a side elevational view of the trip mechanism of this circuit breaker.
- FIG. 7 is a sectional view of the same trip mechanism taken along the lines 7 --7 of FIG. 8, looking in the direction of the arrows.
- FIG. 8 is a sectional view, taken along the lines 88 of FIG. 9 looking in the direction of the arrows, of the same circuit breaker.
- FIG. 9 is' a sectional view of the same breaker taken along the lines 9-9 of FIG. 8, looking in the direction of the arrows.
- FIG. 10 is an exploded perspective view of the trip mechanism and selected components of this circuit breaker.
- FIG. 11 is a perspective view of the bimetallic current sensing element of the trip mechanism, in a cool condition.
- FIG. 12 is a similar view of the same sensing element in a hot condition, such as would be achieved under trip conditions.
- a type S fuse socket has a fuse-like envelope which comprises a molded plastic housing 10 having an elongated, generally cylindrical lower portion 12 formed with type S fuse threads 13. The upper portion of the housing 10 forms and enlarged circular ring 14 by which the breaker may be gripped for threading it into and out of fuse sockets.
- a pair of fixed electrical contacts 16 are mounted in the housing 10. These contacts extend a short distance radially across the interior of the housing 10, and include downwardly extending shanks 16a and 16b respectively (see FIG. 8) which make electrical connections to central and peripheral external circuit breaker electrodes 18 and 20 respectively.
- the top of the circuit breaker housing 10 has a circular opening 22, which provides access to a generally cylindrical hollow interior 24 of the lower portion 12.
- a trip mechanism 26 is received within the interior 24, and the top opening 22 is covered by a disc-shaped molded plastic member 28.
- a gasket 30 in the shape of a washer formed of electrically insulating material goes over the cover 28.
- a circular metal cap 32 goes over the gasket 30, and has a flange 32a which surrounds the housing ring 14 and is crimped thereto.
- Three terraced surfaces 34 in the interior of the housing ring 14 are provided with grooves 36 which increase the electrical tracking path for leakage currents.
- the insulating gasket 30 serves the same purpose.
- Previous fuse envelope type circuit breakers differ in their construction and method of assembly.
- the housing of such prior art devices (corresponding to the present housing 10) was split into two separately molded parts, divided along an axial plane.
- the contacts and the trip mechanism were inserted sidewardly into one half of the split housing, after which the two halves of the housing were assembled and the external cap crimped in place to complete the breaker.
- Contacts 16 are inserted first.
- Vertical contact leg 16a fits within an open vertical channel 24a formed on the interior wall of receptacle 24, and horizontal contact leg is secured to the housing 10 by means of the central external electrode 18, which takes the form of a rivet.
- the peripheral external electrode 20 is fabricated of round wire stock, as seen in FIGS. 1, 4, 5 and 9, instead of being stamped from flat sheet stock as was done in prior art circuit breakers of the fuse envelope type.
- the round wire stock is bent into the generally circular are seen in FIG. 4, so as to embrace the tubular lower portion 12 of breaker housing 10. It is also bent in an axial direction to form a pair of resilient bights b (FIGS. 1, 4 and 5) which make resilient pressure contact with the cooperating electrode inside the fuse socket when the circuit breaker is in use.
- the central portion of the wire is stamped to form a short flat region 20a (see FIGS. 4 and 8) where the electrode 20 can be staked to the circuit breaker, just as flat sheet electrodes have been staked in place in the past.
- Leg 16b of the other fixed contact is then inserted downwardly through a channel 14b molded in the housing ring 14, and staked to the outer peripheral electrode 20 as seen at 38. This secures the contact 16, its leg 16b, and electrode 20 to the housing 10.
- the trip mechanism 26 is of the same general type described in the Ingwersen patents above. It includes a vertically reciprocating molded plastic reset plunger 40 which serves as a carrier for a bimetallic clip 42 and a pair of moveable circuit breaking contacts 44 mounted on the clip. The upper end of the plunger 40 terminates in a cylindrical reset button 46 which extends upwardly through suitable openings 48 formed in the cover member 28, gasket and cap 32. A plunger biasing coil spring 48 is in compression between the bottom of the plunger 40 and the bottom of the interior recess 24 to bias the plunger 44 upwardly, thereby normally keeping the moveable contacts 44 in engagement with the fixed contacts 16 under non-fault conditions.
- the present invention contemplates that there be a friction fit between the upper end of coil spring 48 and a recess 50 (see FIG. 7) which is formed in the bottom of the plunger 40.
- a friction fit between the upper end of coil spring 48 and a recess 50 (see FIG. 7) which is formed in the bottom of the plunger 40.
- the interior surface of the tubular hollow 24 is formed with four radially inwardly extending bosses 24a spaced 90 apartaround the periphery of the interior 24 (see FIGS. 2 and 10).
- Each of the bosses 24a is shaped in the form of a right angle wedge, the comer of which is cut away to form a right angle recess 24b, as best seen in FIG. 10.
- These four recesses 24b together define a socket into which the bottom of the plunger 40, specifically the corners 56a of shoulders 56, are received. The engagement between shoulders 56a of plunger and the rectangular socket defined by the recesses 24b prevents the plunger 40 and thus the entire trip mechanism 26 from turning to any substantial degree once the trip mechanism is lowered into place within the tubular interior 24.
- the lower end of the plunger biasing spring 48 has a conically widened portion 48a at the lower end. This permits the lower end of the biasing spring 48 to fit over and encircle the inner end of the rivet 18, as seen in FIGS. 8 and 9. The effect of this engagement between spring 48 and rivet 18 is automatically to center the trip mechanism 26 within the tubular interior 24, and thereby to insure that the corners 56a of the plunger shoulders 56 will be guided smoothly into their sockets 24b during assembly.
- the cover 28 is placed over the trip mechanism 26 and inserted into the top opening 22 of housing 10 as indicated by arrow 29 in FIG. 3; after which first the gasket 30 and then the cap 32 are put in place over the cover 28, and the cap flange 32a is crimped over the housing ring 14.
- the entire assembly of the moveable contacts 44 and bimetallic clip 42 is pulled downwardly to open the contacts 16, 44, by a pair of trip springs 52 which are tensed between respective lugs 54 on the bimetallic clip 42 and respective shoulders 56 formed at the bottom of the plunger 40.
- the mechanism is prevented from tripping under normal conditions by the bimetallic clip 42, which at ambient temperature is restrained by a latch member 58 assembled to one side of the plunger 40 by means of a rivet 60.
- the latch member 58 is formed with a latching shelf 58a against which one side 42a of the bimetallic clip 42 rests, to restrain downward movement of the clip, as seen in FIGS. 8 and 9.
- the other side 42b of the clip 42 rests against the smooth reverse side 40a of the plunger.
- the spacing between sides 42a and 42b of the clip in a function of temperature the distance between them decreasing at cooler temperatures and increasing at higher temperatures.
- the clip is placed so that sides 42a and 42b thereof embrace the plunger 40, as best seen in FIGS. 6 and 7.
- the sides 42a and 42b constitute a pair of opposed pincers which clasp the plunger to an extent dependent upon temperature.
- the current path through the breaker goes from the central exterior electrode 18 through elements 16c and 16a to one of the fixed contacts 16. Then it enters one of the moveable contacts 44 and flows into the bimetallic clip 42. At that point the current flow divides into two parallel paths, one of which passes through side 42a, and the other of which flows through side 42b, of the clip 42. The two parallel current paths are rejoined at the opposite contact 44, and then proceed to the associated fixed contact 16. Thereafter the current flow exits from the circuit breaker via element 16a and the peripheral exterior electrode 20.
- the current passing through the bimetal clip 42 is of such proportions that the heat dissipated in the clip expands the distance between sides 42a and 42b.
- the clip 42 becomes unlatched, and the trip springs 52 pull the clip 42 and movable contacts 44 down into the tripped position illustrated by FIGS. 6 and 7. This separates movable contact 44 from fixed contacts 16, and opens the circuit to interrupt the fault current.
- side 42b thereof guides against the adjoining smooth side of plunger 40.
- the one-piece integral housing 10 of the present circuit breaker has several advantages in this respect; it has greater resistance to the internal pressure of expanding gasses, and it has no axial seam lines through which the carbon material can escape. But in addition, the circuit-breaker of this invention incorporates certain extra features which help to defect the destructive effect of excessive heating inside the breaker.
- One of these features is the provision of a pair of vent holes 62 (see FIGS. 2, 4 and 9) on the bottom surface 12a of the lower portion 12 of circuit breaker housing 10. In one embodiment, these holes 62 were each roughly three sixty-fourths inch in diameter.
- vent holes play an important role in enabling the type S circuit breaker of this invention, for the first time, to withstand the internal pressures generated under fault conditions encountered in some of the more severe U.L. tests. It is believed that the-vent holes function by providing an escape for the internal pressure built up by not expanding gas in the interior of the breaker.
- the plastic molded cover 28, which closes the top opening 22 of housing 10 is integrally formed with a pair of D-shaped bosses 64, which project into the interior of the circuit breaker housing 10, on either side of the fixed contacts 16 (see FIGS. 3, 8 and 9).
- These bosses 64 also permit the type S circuit breaker of this invention to withstand the high internal pressures to which it is subjected during severe U.L. test procedures.
- the bosses function by redirecting the force of the hot expanding gasses inside the breaker, downwardly toward the holes 62, thereby enhancing the ventilating effect of those holes.
- each side 42a and 42b of the bimetallic clip is cut out to form a window 4211 which reduces the cross-sectional area of the path through which the fault current flows, raises the electrical resistances, and thereby permits the breaker to trip at the desired current rating.
- a much higher current level would be required to produce the same degree of bimetal heating if the current path through the bimetallic clip included the area of windows 42d.
- the removal of the central window area 42d forms each side 42a and 42b of the bimetallic clip into a U-shaped member.
- Each U-shaped member comprises a pair of vertical legs 42c on opposite sides of the window 42d, and a horizontal cross-bar 42f extending across the bottom of the window 42d.
- tangs 42g extend horizontally from each of the vertical legs 42e, part way into the adjoining window 42d, and con- I upper or trailing horizontal edges 42h. This latter edge 42h of side 42a has a tendency to interfere with the latching shoulder 58a during reset of the circuit breaker after tripping.
- the resetting of the circuit breaker is accomplished by pressing on the reset button 46, and thus driving the entire plunger 40 downwardly.
- the latch member 58 then moves downwardly with the plunger 40, until the shelf 58a thereof comes under the leading edge 42c of side 42a of the bimetallic clip. This motion recaptures and relatches the clip 42.
- the reset button 46 is released, and the biasing spring 48 drives the plunger back up to its normal operating position, carrying the clip 42 and moveable contacts 44 with it.
- the edge of the latching shoulder had a tendency to catch the trailing edge of the adjacent horizontal cross-bar, thus preventing smooth resetting of the circuit breaker.
- the circuit breaker of the present invention provides an additional tang 42a which extends vertically upwardly from the horizontal trailing edge 42h, andprojects into the cutout window area 42d.
- the height of the tang 42a is such that when the bimetallic clip 42 is in its tripped position defined by the limiting shoulders 66, the top of the tange 42a adjacent the latching shelf 58a is somewhat above the level of the latching shelf. Thus the upper end of the tang 42i can not move past the latching shelf 58a.
- the vertical tang 421' guides against the edge of the latching shelf 58a. This prevents the trailing horizontal edge 42h from catching against the latching shelf 58a and interfering with smooth resetting of the breaker.
- both sides of the bimetallic clip 42 have the vertical tangs 42i, even though there is only one latching shelf 58a in the circuit breaker illustrated herein.
- the trip current rating of the mechanism is reduced with extreme simplicity and economy by simply making a through cut 70 across one side,e.g., 42a, of the bimetallic clip 42.
- the cut 70 extends vertically from the upper tip of vertical tang 421 all the way down to the lower edge 42c, and also extends completely through the depth of side 42a of the bimetallic clip.
- the two different approaches are possible, both within the contemplation of this invention.
- the through cut may be made wide enough, as illustrated by FIG. 1, so that even at ambient temperature it effectively interrupts the current path which would otherwise be provided by side 42a of the metallic clip. As a result, at all times all the current between contacts 44 must flow exclusively through side 42b.
- the through cut 70 is formed not by removing any material and leaving the sides of the cut separate from each other, but simply by shearing through the material of side 42a, thereafter leaving the sides of the cut in intimate contact with each other, as illustrated in FIG. 1].
- the current will divide into two parallel paths and flow through both sides of the bimetallic clip 42a and 42b in the manner described above.
- the warping of the bimetallic material in response to heating causes the bimetallic clip 42 to pull the edges of the cut 70 apart. This action is illustrated in FIG.
- circuit breaker of this invention provides numerous advances over breakers of the same general type known to the prior art.
- the movement of the current sensing clip upon tripping is limited by a pair of stop shoulders which are positioned so that the trip springs are never allowed to become completely relaxed, and this avoids the danger of disassembly.
- a tang is provided on the bimetallic clip which remains across the latch shoulder when the bimetallic clip bottoms on the limiting shoulders, and thereby prevents undesirable engagement between the edge of the bimetallic clip and the latch member during resetting of the breaker.
- the fuse-shaped circuit breaker envelope includes a housing of one-piece, hollow, open-ended construction, and has vent holes at one end and a cover member with D-shaped bosses at the other end, all of which has advantages in permitting a type S circuit breaker to withstand U.L. qualification testing. Accordingly, a new method of assembling the breaker is provided, in which all the internal parts are inserted through the open end of the hollow housing. During this operation it is advantageous for the plunger biasing spring to be frictionally received within an appropriate recess at the bottom of the plunger.
- the bimetallic clip may be formed with a through cut, in order to de-rate the breaker easily and economically. Finally, further economies are achieved by forming the peripheral external electrode of inexpensive round wire stock, appropriately flattened at one location to permit staking for mechanical and electrical connection thereto.
- a circuit breaker comprising a one-piece hollow housing, one end of which is adapted to thread into a femal socket, a thermomechanical trip mechanism mounted inside said housing, the opposite end of said housing having an opening for inserting said trip mechanism with a first orientation into said housing, and a cover member closing said opening to retain said trip mechanism, said cover having boss means extending generally perpendicularly into the interior of the housing to redirect the force of expanding gases in side the housing.
- a breaker as in claim 2 wherein said cover member has two such bosses on opposite sides of a center plane, and said housing hastwo such vent holes on opposite sides of a center plane.
- a breaker as in claim 1 further comprising at least one contact fixedly mounted on'said housing wherein said housing has a socket extending in a preferred direction into the interior of said housing, said trip mechanism comprising a plunger and at least one movable contact mounted on said plunger to form a breakable switch with said fixed contact, said plunger being mounted in the socket for reciprocating movement along said preferred direction during operation of said trip mechanism, said socket being shaped to allow said plunger to reciprocate in said preferred direction but to restrict rotation of said plunger about said preferred direction whereby to retain said plunger-mounted movable contact in' relationship with said fixed contact.
- a breaker as in claim 1 wherein said trip mechanism comprises a plunger movable during operation of said mechanism, a recess formed at one end of said plunger, and a compression spring frictionally retained within said plunger recess and operable to bias said plunger for movement relative to said housing.
- a method of manufacturing and assembling a circuit breaker comprising the steps of fabricating a one-piece hollow housing having an interior space extending from an opening in the housing to a lower recess terminating at a bottom wall and provided with a pair of separated stationary electrical contacts extending into the interior space at the opening;
- the capturing step includes placing a cover having spaced embossments over the interior space with the embossments extending inwardly to locate the movable electrodes between the embossments.
- a housing for retaining an overload current trip mechanism in a'circuit breaker assembly comprising a unitary hollow housing being molded with an interior space extending from an upper opening to a lower recess terminating at a bottom wall, a pair of separated electrical contacts mounted to the housing and extending into the upper opening to capture the current trip mechanism below the contacts, said upper opening being shaped to receive the current trip mechanism in a first orientation selected to enable the trip mechanism to be inserted below the contacts, said lower recess being shaped to enable the trip mechanism to be rotated to a second orientation for operative movement with respect to the contacts, and means for preventing the trip mechanism from escaping from its operative orientation to maintain an operative relationship between the trip mechanism and the electrical contact throughout circuit breaker operations.
- circuit breaker as claimed in claim 9 wherein said means further includes a cover on the housing to enclose the interior space at the opening, said cover being provided with an embossment lected to enable said trip mechanism to rotate during insertion into the housing with said trip mechanism in a current overload tripped condition.
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Abstract
Description
Claims (12)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US15993071A | 1971-07-06 | 1971-07-06 |
Publications (1)
Publication Number | Publication Date |
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US3771087A true US3771087A (en) | 1973-11-06 |
Family
ID=22574713
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00159930A Expired - Lifetime US3771087A (en) | 1971-07-06 | 1971-07-06 | Circuit breaker, trip mechanism and method for manufacturing same |
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Country | Link |
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US (1) | US3771087A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3949336A (en) * | 1975-01-08 | 1976-04-06 | Square D Company | Sequential resetting circuit interrupter |
US5130684A (en) * | 1990-03-27 | 1992-07-14 | Square D Company | Circuit breaker with self-aligning thermal trip |
US6538549B1 (en) | 2001-08-30 | 2003-03-25 | Blue Sea Systems | Advanced electrical circuit breaker system and method |
US20080137254A1 (en) * | 2006-12-06 | 2008-06-12 | Emerson Electric Co. | Circuit breaker |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2461126A (en) * | 1947-05-17 | 1949-02-08 | Overturf William Kendall | Resettable circuit breaker |
US2576815A (en) * | 1946-05-06 | 1951-11-27 | Edward V Sundt | Fuse plug circuit breaker |
-
1971
- 1971-07-06 US US00159930A patent/US3771087A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2576815A (en) * | 1946-05-06 | 1951-11-27 | Edward V Sundt | Fuse plug circuit breaker |
US2461126A (en) * | 1947-05-17 | 1949-02-08 | Overturf William Kendall | Resettable circuit breaker |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3949336A (en) * | 1975-01-08 | 1976-04-06 | Square D Company | Sequential resetting circuit interrupter |
US5130684A (en) * | 1990-03-27 | 1992-07-14 | Square D Company | Circuit breaker with self-aligning thermal trip |
US6538549B1 (en) | 2001-08-30 | 2003-03-25 | Blue Sea Systems | Advanced electrical circuit breaker system and method |
US20080137254A1 (en) * | 2006-12-06 | 2008-06-12 | Emerson Electric Co. | Circuit breaker |
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Owner name: AMSTAR TECHNICAL PRODUCTS COMPANY, INC., 1251 AVEN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:NORLIN INDUSTRIES, INC., A CORP. OF DE.;REEL/FRAME:003957/0214 Effective date: 19811208 |
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Owner name: MECHANICAL PRODUCTS, INC., A CORP. OF DE. Free format text: MERGER;ASSIGNORS:MECHANICAL PRODUCTS, INC. (MERGED INTO);ASR 7, INC. (CHANGED TO);REEL/FRAME:004759/0035 Effective date: 19861231 |
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Owner name: CITIBANK, N.A.,NEW YORK Free format text: SECURITY INTEREST;ASSIGNOR:MECHANICAL PRODUCTS, INC., A DE CORP.;REEL/FRAME:004764/0301 Effective date: 19870916 Owner name: CITIBANK, N.A., 641 LEXINGTON AVENUE, NEW YORK, NE Free format text: SECURITY INTEREST;ASSIGNOR:MECHANICAL PRODUCTS, INC., A DE CORP.;REEL/FRAME:004764/0301 Effective date: 19870916 |
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