US2470050A - Drain arrangement for enclosures such as enclosures of explosionproof motors or the like - Google Patents

Description

y 1949- G. E. PETTERSON 2,470,050

' ARRANGEMENT FOR ENCLOSURES SUCH AS ENCLOSURES 0F EXPLOSION-PROOF MOTORS OR THE LIKE 2 Sheets-Sheet 1 Filed Feb. s, 1946 INVENTOR. 5 7 Gus/by 5 Fem/awn mxm May 10,1949; G. E. PETTERSON 2,470,050

DRAIN ARRANGEMENT FOR ENCLOSUR SUCH AS ENCLOSURES 0F EXPLOSION-PROOF MOT OR THE LIKE Filed Feb. 5, 1946 2 Sheets-Sheet 2 j \\\\\\\\\\\m L215 #3 IN V EN TOR:

Gus/0r E Pew/son Hffarneys Patented May 10, 1949 DRAIN ARRANGEMENT FOR ENCLOSURES SUCH AS ENCLOSURES OF EX?LOSION- PRQOF MGTORS OR THE LEKE Gustav E. Patterson, Florham Park, N. J assignor to Continental Electric Company, Inc, Newark, N. J., a corporation of New Jersey Application February 5, 1946, Serial No. 645,563

1 20 Claims.

This invention relates to what are known as explosion-proof motors or other devices provided with enclosures constructed so that any explosion, ignition, burn-out, fire or excessive temperature rise occurring inside the enclosure cannot ignite any explosive gas mixture or vapor on the exterior of the enclosure.

Among the objects of the invention are enclosed devices of the foregoing type embodying drainage means providing for a continuous drainage of liquids, such as condensates accumulating in the interior of the enclosure, as Well as for forcible ejection or expelling of such liquids and foreign matter, without in any manner decreasing the effectiveness of the enclosure in preventing ignition of a combustible mixture on the exterior of the enclosure by an explosion, ignition or the like occurring in the interior of the enclosure.

The foregoing and other objects of the invention will be best understood from the following description of exemplifications thereof, reference being had to the accompanying drawings wherein Fig. l is a partially-elevational and partially cross-sectional View of a totally enclosed explosion-proof motor equipped with drainage means exemplifying the invention;

Fig. 2 is a side elevational view of the bottom part of the motor of Fig. 1 as seen from the right side thereof;

Fig. 3 is a cross-sectional view along line 33 of Fig. 2 showing the general arrangement of a drainage structure exemplifying one form of the invention;

Figs. i and 5 are views similar to Fig. 3 showing the drainage arrangement in two other operating positions thereof;

Fig. 6 is a cross-sectional view along line 5-5 of Fig. 3;

Fig. (3A is a view similar to Fig. 6 of a modifled form. of drainage arrangement; and

Fig. 7 is a partially diagrammatic and. partially cross-sectional View of a remotely controlled and automatically operating enclosure drainage system exemplifying one form of the invention.

Although the enclosure drainage arrangements of the invention are useful in other applications, they will be described as applied to a totally enclosed self-ventilated motor intended for operation in surroundings which may contain explosive gaseous mixtures commonly known in. the art as explosion-proof motors. Such explosionproof motor is so constructed that any explosion, ignition, burning or fire occurring inside the motor cannot ignite any explosive gas mixtures or vapors on the exterior of the motor. In order to be acceptable, such motor must meet the following requirements:

or burn out, it will radiate the heat rapidly enough to prevent ignition of the gas by reason of raised surface temperature of the exposed parts of the enclosure.

l) The various parts of the motor and its enclosure must be so designed as to prevent the possibility of any sparking external to the motor caused by conditions, such as striking of moving or stationary parts on each other.

(5) The motor and its enclosure must be so u designed that should a careless workman neglect to instal all assembly bolts or other analogous parts, there will be no direct opening or passage left between the interior of the motor enclosure and the outside atmosphere.

As a rule, such explosion-proof motors arev constructed so as to permit the motor to breathe and permit gas or air to enter from the exterior into the interior of the motor enclosure, while assuring that should any explosion or flame 0c- 3 our in the interior of the motor enclosure, the

ignited gases will be sufiiciently cooled before reaching the exterior atmosphere that they will not produce ignition of combustible mixtures present therein. Since such motors are subject to intermittent operation and wide changes in temperature and variations of the humidity conditions in the exterior atmosphere which is breathed in and out by the motor, they accumu late liquids, such as water of condensation,

'- within the interior of the motor enclosure. Such accumulation of Water in the interior of the motor enclosure is very objectionable because it may affect the insulation of the electrical elements of the motor which are exposed in its interior. As a result, there has long existed the need for a simple and effective drainage arrangement for such motors.

The resent invention solves this problem by providing the motor enclosure with a drainage arrangement which makes it possible for the .1 water and other liquids accumulating in the motor enclosure to drain continuously to the exterior without in any way impairing its characteristics as a so-called explosion-proof motor. In addition, the drainage arrangement of the invention is so designed as to make it possible to forcibly eject liquid accumulating in the interior of the motor enclosure without impairing its characteristics as a so-called explosion-proof motor.

Furthermore, in accordance with the invention, the drainage arrangement for an explosion-proof motor is arranged to be remotely controlled and also to be automatically actuated at predetermined time intervals or whenever the motor is started for bringing about ejection of liquid accumulated in the motor.

In general, in the drainage arrangement of the invention, a bottom Wall portion of the enclosure is provided with an elongated passage from the interior to the exterior through which liquid accumulating in the enclosure may drain to the exterior thereof. An elongated plunger member is longitudinally movable in the passage over a predetermined limited stroke range, and the facing surfaces of the plunger member and the drainage passage are of such character and so shaped that in all positions of the plunger member over its stroke range, they confine the flow of liquid through the passage to gap-like passage elements of sufficiently small cross-section and sufiicient passage length so as to quench ignited gases flowing therethrough before they are discharged from the passage to the exterior of the enclosure, while permitting drainage of liquid through said passage elements to the exterior of the enclosure. The facing surfaces of the plunger member and the passage are of such varied configuration along different portions of their length that in an interior position of the plunger member they form a trap compartment for receiving and entrapping a quantity of the liquid accumulating in the enclosure, and that on moving the plunger member to an outer position, an interior section of the plunger member will eject at least a portion of the entrapped liquid from the passage.

In accordance with the invention, the wall portion of the passage is made in the form of a duct member removably held within an opening of the enclosure. Furthermore, the duct member and also the plunger member are so mounted and correlated to the other elements of the enclosure as to prevent removal of elements of the duct structure or the plunger structure from the enclosure while the enclosure structure is in its normal operating condition.

[in one specific form of the invention, the plunger member is provided with an outer section, an inner section and an intermediate section differing in their exterior contours so that in one position of the plunger member the intermediate section forms with the facing passage surface a trap compartment for receiving and entrapping a quantity of the liquid accumulating the bottom portion of the enclosure.

According to the invention, remotely controlled electrically operating actuating means, such as electric relay or solenoid means are combined with the plunger structure so as to operate it from one position to the other and bring about ejection of quantities of liquid accumulating in the bottom part of the enclosure each time the electrical actuating means are subjected to a control action, for instance, by sending therethrough an electric current or interrupting an electric energizing current passing therethrough. The electrical plunger actuating means may be mounted either in the interior or on the exterior of the enclosure and they may be readily combined with automatically operated control means so as to operate the plunger each time the motor is started for performing a sequence of liquid ejecting operations sufficient to assure that each time the motor is set in operation, the liquid accumulating in the interior of the vessel is below a predetermined maximum level. Alternatively, the control means may be controlled by timer means at predetermined timing intervals, for instance, every 12 hours or every 24 hours, for actuating the plunger element a predetermined number of times and causing it to eject quantities of liquid accumulating in the bottom of the enclosure.

A specific form of an explosion-proof electric motor combined with a drainage arrangement in accordance with the principles of the invention will now be described in connection with Figs. 1 to 5. The explosion-proof motor shown in Fig. 1 is provided with the usual laminated stator core structure H having stator windings 82 held suitably afiixed to the inner Wall surface portions of the cylindrical casing shell l3 surrounding the stator structure. A magnetic rotor core is cooperating with the stator is revolvably mounted on a shaft 15 suitably journalled in bearings, not shown, held within the end bell members it, i! forming with the cylindrical casing shell 13 an explosion-proof enclosure around the motor elements II, M.

A fan I8 afiixed to an end portion of the motor, not shown, projecting beyond the end bell H, impels cooling air through a plurality of axially extending external cooling duct passages ill of the casing shell IS in the manner indicated in Figs. 1 and 2, so as to cool the motor. In order to secure a better heat exchange, the rotor of such motor is also in many cases provided with additional air impelling elements, not shown, which circulate the air or the atmosphere enclosed within the motor enclosure along the air flow path indicated by the dash-line arrows 2! by way of cooling passages of the rotor core i i, stator core I I and additional cooling duct passages 22 formed in the casing shell i3 between the outwardly open ing duct passages H9.

The fan i8 is usually housed within a fan cover bell 24 suitably fixed to the casing structure and arranged to guide the externally circulating cooling air toward the fan and from the fan through the externally cooling ducts is along the air flow path indicated by the full line arrows 25.

The bearing as well as all other junctions between the enclosure elements of the motor are designed to meet the requirements of explosion proof motors and assure that all passages extending between the interior of the enclosure to the exterior are of sufficient length and sufiici-ently small cross section as to cause gases ignited in the interior of the enclosure to be quenched before they reach the exterior atmosphere.

According to the invention, the motor enclosure is combined with drainage means arranged to provide a continuous drainage path for liquids accumulating in the lowermost part of the motor enclosure and also to enable forcible ejection of substantial quantities of liquid from the interior of the enclosure without in any way impairing the explosion proof character of the motor.

As indicated in Fig. 1 and in the enlarged views of Figs. 2 to 5, the lowermost portion of the enclosure in which liquid will tend to accumulate is formed by the centrally located lowermost internal ventilating duct 22 of the motor enclosure shell l3. In the end wall portion of the enclosure shell 13 bordering the lowermost internal vent-i lating duct 22 has formed therein a longitudinal bore opening 3! to provide drainage of liquid accumulating in the interior of the motor enclosure to the exterior thereof, the bore 3| extending in a direction generally parallel to the axis of the enclosure. Although the bore 3i itself may serve as a drain passage for draining liquid by gravity, there is shown mounted therein a distinct drain duct member 32 of metal, such as brass, arranged to fit and close up the bore 3| of the casing shell 13.

As indicated in the enlarged views of Figs. 2 and 3, the interfitting surfaces of the bore El and the drain duct member 32 are of generally circular shape and have interfitting threaded sections 34 so that the drain duct 32 may be removed or replaced by turning it along its threaded engagement with the bore. The outer end of the drain duct member 32 is shown provided with a hexagonal head 33 arranged so in relation to an adjacent rim projection [-1 of the end bell l6 of the motor enclosure so as to make it impossible to remove the duct member 32 from its position within the bore 3! of the casing shell l3 as long as the end bell I6 is held affixed in its operating position to the casing shell is by clamping screws iii-2. lhis arrangement prevents unscrewing and removal of the drain duct member 32 unless the motor enclosure has first been dismantled by removal of the enclosure end hell it of the motor. Furthermore, the length of the bore 3! along which it interfits with the drainage duct member 32 positively assures that any gases ignited in the interior of the enclosure will be quenched before passing therebetween the exterior of the enclosure.

The drain duct member 32 is provided with an internal axially extending drainage passage generally designated 35 within which is located a plunger member generally designated 35 arranged for longitudinally moving within the passage 35 between an inner position which is shown in Fig. 3, and in an outer position which is shown in Fig. 5. The internally facing surface of the drain passage 35 and the outwardly facing surface of the plunger member 36 have such varied configuration along different portions of their lengths as to confine the flow of gases, or in general fluid, through passage spaces formed therebetween to gap-like passage elements of sufliciently small cross section and sufficient passage length to assure that ignited gases flowing thereto from the interior of the enclosure will be quenched before they reach the exterior of the enclosure while permitting drainage of liquid through such passage elements at least in one of the positions of the plunger memher.

In the drainage arrangement shown, generally designated 36, the drain passage 35 of the duct member 32 is provided with an inner passage section 35-I, an intermediate passage section 35-2, and an outer passage section 35-3 of accessibly smaller cross section. The outer surface of the plunger member 3i: is shown pro vided with a corresponding inner plunger section 36-l, an intermediate plunger section 556-2, and an outer plunger section 35-3 shaped and arranged for cooperation with the corresponding passage sections of the drain passage 35 in the manner described below.

In a specific form of drain arrangement shown in the drawings, the inner section 36-l of the plunger member is of a simple cylindrical shape; the intermediate plunger section 35-2 or similar cylindrical shape but of smaller diameter; and the outer plunger section til-3 is 01 likewise generally cylindrical shape and of a diameter smaller than the inner plunger section SS-l, but larger than that of the intermediate plunger section 35-2.

In a specific f rm of the drain arrangement shown, the plunger member is intended to be normally held in its inward position shown in l and 3. In this normal position the outer plunger section and the operating facing drainage passage section 35-3 are of such relative diameters and so shaped as to confine between them gap-like passage elements of sufiiciently small cross section and suflicient passage length for assuring that gases ignited in the in terior of the enclosure on passing through the passage elements will be quenched before they '1 reach the exterior of the enclosure and while permitting drainage of liquid through such pas sage elements from the interior to the exterior of the enclosure.

Furthermore, when the plunger member is in its normal inward position shown in Fig. 3, the other plunger sections (35-2, 35-! and the cooperating facing drainage passage section 35-2, are of such relative diameters and so shaped to provide therebetween a relatively free passage of liquid to the region or the gap like passages confined between the facing surfaces of the plunger section 36-3 and drainage passage section 35-3.

Furthermore, in the inward position of the s! 'lgel member the outwardly facing plunger section 23 5-2, til-5 form with the facing ainage passage sections 35-2, 35-! relatively oly flow by gravity and upon reaching the gapsage elements confined between the inner section and the facing drain passection will drain therethrough to the exterior of the enclosure. In order to provide for the required -ainage space between the outer plunga plunger section in its inward position, and the facin drainage passage section 35-3 the exterior of one of the facing surface elements is provided with plurality of longitudinal extending rooves or cut-offs in the manner indicated in Figs. 6 or As shown Fig. 6, the external surface of the plunge 'ection 3 is provided. with a series of longitudinal grooves which form with the facing portions of the drainage passage section gap-like passage elements of cross section as to permit the desired drainage of liquid from the interior of the enclosure to the exterior while at the same time meeting the requirements with. respect to the quenching of ignited gases passing through from the interior to the exterior of the enclosure.

Alternatively, as shown in Fig. 6A, the required cross section of the passage elements may be obtained by providing the cylindrical exterior of the plunger section with a plurality of axially extending fiat surfaces 35-? giving it a polygonlilre structure the sides of which form with the facing cylindrical surfaces of the duct passage section 55-3 a gap passage element through which liquid may drain from the interior to the exterior of the enclosure while the plunger member 35 is in its inner normal position shown in Fig. 3.

The cooperative relationship of the plunger member 36 and the drainage passage 35 is such that it not only assures drainage of liquid from the interior to the exterior of the enclosure but makes it also possible to forcibly eject to the exterior of the enclosure quantities of liquid accumulating in the interior of the enclosure by impartin to the plunger member a plurality of one or more reciprocatory movements.

As indicated in Fig. 3, in which the plunger member is shown in its inward position the intermediate plunger section 362 is of a suificiently smaller cross section than the facing surface wall portion of the drainage passage 35 as to provide therebetween a reception space or trap for a substantial quantity of liquid accumulating in the lowermost portion of the enclosure.

Furthermore, innermost section 35l of the plunger member is arranged to form a piston-like member which upon moving with plunger member 55$ in outward direction from the position shown in Figs. 4 and 5 will act as a piston expelling liquid entrapped within the passage section -4 into the portion of the outer drain passage section 353 into which the intermediate plunger member 362 enters so that when the plunger reaches the outermost position, shown in Fig. 5, a quantity of liquid so entrapped by the pistonlike action of the plunger section %i will be expelled from the drain passage section 353 to the exterior thereof.

The relative length of the inner, intermediate and outer sections of the plunger 35 and the cooperating surface portions of the passage 35 are so proportioned, that each time the plunger member is moved from its inward to outward position at least a portion of liquid accumulated in the e section 352 will be entrapped and ejected through the outlet end of the passage 35 by the outward movement of the piston-like plunger section Sit-l.

Furthermore, the exterior surface of the inner plunger section 3tl is of such shape and dimension in relation to the facing wall surface of the intermediate drain passage section 35-2 that in all positions of the inner drain plunger section .'-I=.Gl as it moves through the intermediate drain passage section 35-2 a piston portion thereof will confine with the facing surface portions of the intermediate drain passage section 35-2 gap passage elements of suiiicient length and sufficiently small cross section so that in the conjunction with the flow passage elements formed between the outer plunger section 36-3 with the facing outer drain passage sections 35-3 gaplike passages of suflicient over-length and sumciently small cross section to assure that ignited gases passing therethrough will be quenched before they reach the exterior of the enclosure while permitting liquid to drain through such passage elements in all positions of the plunger member between its inner position shown in Fig. 3 and its outer position shown in Fig. 5.

The plunger member may be operated either manually or remotely, for instance, through an electrical control circuit. As indicated in Figs. 1 to 5 a knob 31 may be afiixed to the outer end of the plunger member 36, as by a screw 3'l-I, which permits manual reciprocation of the plunger member 36 for efiecting forcible ejection of liquid from the interior to the exterior of the motor enclosure in the manner described above.

Without in any way limiting the scope of the invention, and in order to enable those skilled in the art to readily practice the invention, there are given below structural data of one form of drainage arrangement of the invention which proved effective in providing for eiiective drainage of a conventional explosion-proof motor and also for the forcible ejection of liquid from the interior of the motor enclosure:

The outer plunger section 36-3 and the cooperating drain passage section 353, which provide the drainage passage in the inward position of the plunger, had an overall length of about 1 /2 inches, and the outer diameter of the outer plunger section 36-3 was .435 inch.

The diameter of the cylindrical passage through the outer drain passage section 35% was .440 inch, giving a total diametrical clearance over the outer diameter of the knurled or grooved outer plunger section 3t-3 of about .005 inch.

The diameter of the intermediate cylindrical drain passage 352 was about .625 inch and the diameter of the piston or inner section 36-l of the plunger member was .615 inch, giving a diametrical clearance for drainage of about .010 inch.

It will be noted that the diameter, or, in general, the overall width of the outer plunger section 363 is smaller than the diameter of the inner plunger section 36-4, and that they are so correlated to the shape of the passage that the plunger section may be as a unit inserted in its operative position within the drainage passage 35 of the duct member 32 through the relatively wider open end portion of its inner duct passage sections 35-2, 35-l.

Means are also provided to prevent the plunger member from being moved in inward direction through the drain passage 35 of the duct member -32 to a position in which it might decrease the effectiveness of the drain arrangement in assuring that ignited gases passing therethrough are quenched before they reach the outer end of the drain passage 35. In the arrangement shown, the inward movement of the plunger member is positively stopped by providing a suitable stop projection in the path of the plunger member which prevents its inward movement beyond the normal position shown in Fig. 3 in which the outer plunger section 35-3 in cooperation with the surrounding outer drainage passage section 3'53 provide the normal drainage passage, in the manner described above.

In the arrangement shown, such stop is provided by a projecting stud portion 39 having a threaded end engaging and fixedly held in a suitable threaded hole formed in the wall portion of the enclosure shell I3 located at the inner end of the plunger member 36, the inner end of the stud 39 being also shown provided with a slit for a screw driver used in screwing it in its fixed stop position.

It will be noted that the round head or knob 37 which serves for manually reciprocating the plunger 36 is also provided with inwardly extending stop projections 3'l'2 which serve as additional stops limiting the inward movement of the plunger member 36. The outermost posi tion of the plunger is limited by the innermost edge region of the relatively wide inner plunger section 36-4 which comes into engagement with the inner edge wall region of the outer passage section 353 of the drain passage or duct member 32.

In the drain arrangement described above, the intermediate plunger section 36-4 and the intermediate drain passage section 352 are of such relative diameters as to provide an appreciable space for the entry and entrapping of liquid by gravity feed from the interior of the enclosure. Furthermore, it will be noted that when the plunger member is in its outermost position, its grooved or knurled surface exterior is accessible and may be wiped clean of dirt or sediment or other foreign matter. Obviously, thedrain arrangement of the type described above maybe also arranged so that the axis of its drain passage is in downward direction, in which case the drainage action will be promoted.

According-to the invention, a drainage arrangement of the type described above is also combined with remotely ccatrolled means for in terniittent actuation thereof to perform liquid ejecting operations eject liquid accumulating in the interior of the enclosure as well as for automatic operation of such ejection control arrangem nt at predetermined intervals or at predetermined operating conditions of the motor.

'7 indicates diagrammatically one form of such automatic and remote control of the liquid ejecting operat us of a drainage arrangement exemplifying the invention. The operating coil 3 a drainage arrangement of the type described 'I in connection with Figs. 1 to 6.

The coil of the solenoid 4| is arranged to be selectively energized by an electric supply circuit connected to a source of electric energy indicated by plus or minus signs, the energizing circuit including a switch 44 so that each time the switch is closed, the solenoid 4| will be operated to move the drainage plunger from its inward position shown inFig. 3 to the outer position shown in Fig. 5 for ejecting quantity of liquid from the interior of the enclosure. lhe plunger may be arranged to be biased so to automatically return to its inner position, as by a tensioned spring connected to projections extending from the plunger head 3? and from a facing portion of the enclosure structure It.

With such arrangement, manual actuation of the switch M will energize the solenoid to impart to the plunger a liquid ejection operation, the plunger being returned to its normal inner position upon opening of the switch 64. Means also provided to assure that the control switch at is actuated to the operated position for a predetermined period of time required in order to the plunger to be actuated from the inner to the outward position and cause it to be released for returning to the inward position upon performing a liquid ejecting operation. Such control arrangement may be provided by a rotary cam member 43 arranged to be rotated at a slow for instance, by motor means til embodying suitable speed reducing means and arranged to be energized through a circuit connected to a source or" supply indicated by plus or minus signs whenever a control switch 43 is closed.

The cam member 46 is provided with cam projections 46-1 of such angular or .peripheral All switch 4 8.

length and so arranged that when the cam meniber 46 is rotated by the motor means 4'1, the successive cam projections 46-l will operate the switch 44 to successively energize the solenoid for actuating the plunger 36 to perform a liquid ejecting operation, th plunger being released to its inward position after each cam projection '46 leaves its engagement with the switch 44 and before its next cam'projection comes into engagement with the switch 44 for actuating it'to the operated position.

With such arrangement, the motor 41 will be energized as long as switch 48 is'actuated to the operated position and causes the motor 41 to energize and drive its cam 46, causing the latter to operate the solenoid control switch 44 and thereby energize the solenoid during a predetermined sequence of ejection intervals duringwhich the plunger is successively actuated to forcibly eject or expel a quantity of liquid from the interior of the enclosure.

In order to assure that upon completing the desired sequence of liquid'ejecting operations the plunger member will be returned to its inward position, interlocking means are provided to assure-that the solenoid control-switch 44 is automatically released to its solenoid de-energizing position when a sequence of liquid-ejectingoperations is terminated by the-opening of the control In the arrangement shown, the interlocking means are formed by combining the solenoid control switch 44 with another set of-interlocking switch contacts 49 connected parallel'to the motor control switch 48 so that if motor control switch 48 is actuated from theoper-ated to the non-operatedopen position, whilea cam projection it-l keeps the-solenoid controlswitch '44 in the operated position, the interlocking switch contacts 49- will keep the motor energized until the cam projection-which keeps the solenoid control switch '44 and with it the interlocking switch -49 in the operated positionwill release them to the non-operatedposition shown.

Furthermore, in accordance with the invention, automatic means are also provided for actuating the drainage arrangement at predetermined timed intervals-for instance, each morning just before or just after an explosion-proof motor, such as shown in Fig. 1, is started after the night rest periodfor causing the drainage arrangement to be operated a desired number of times sufficient to assure ejection of any liquid accumulated-in the interior of the enclosure during the period from the last previous liquid ejecting operation.

In thearrangement shown, the automatic control means are indicated in the form of a timer motor 5i connected throughsupply lines52 to, an alternating current source, and provided with adjustably settable timing means arranged to actuate a set of switch contacts 53 to an operated position and keep them-in the operated position during a predetermined timingperiod required in order to cause an electrically controlled liquid ejecting mechanism of the type described above to perform the required succession of liquidejecting operations. Adjustably setswitches 53 operated by a timing mechanism SI of the general :type described above are wellsknown in the art and requireno further description.

It. may be pointed out in this connection that the electric energy supply source for-the solenoid 4| andthe cam drive motor 41 will,-as a rule, be alternatingcurrent supply sources, although-they outward plunger aeraoso are indicated in" the drawings for the sake of simplicity by plus and minus signs.

It will be apparent to thos skilled in the art modifications and applications of the same. It

-' is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specific exemplifications of the invention described herein.

I claim: 1. In a drain arrangement for enclosure structure, such as an enclosure of an explosion-proof i electric motor: a duct structure for a lower wall member of said enclosure having an elongated passage for connecting the interior to the exterior of the enclosure and draining liquid accumulating in the enclosure to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position;

the cross-sectional area of a trap portion of the length of said passage being larger than the crosssectional area of a trap portion of the length of said plunger member extending therethrough when said plunger member is in the receiving position to form between the trap portions of the passage and the plunger member a trap compartment receiving liquid from said enclosure when said plunger member is in the receiving position; an inward ejecting portion of the length of said plunger member being of a greater cross-sectional area than the trap portion of the plunger member for causing said ejecting portion to eject liquid from the compartment to the exterior of the enclosure when said plunger member is moved from said receiving position to said delivery position; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like pass-age elements of sufficiently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage.

2. In a drain arrangement for enclosure structure, such as an enclosure of an explosion-proof electric motor: a duct structure for a lower wall member of said enclosure having an elongated passage for connecting the interior to the exterior of the enclosure and draining liquid accumulating in the enclosure to the exterior thereof; an elongated plunger member longitudinally "movable in said passage between an inner receiving position and an outer delivering position;

said plunger member having an inward plunger section, an intermediate plunger section and an section, said intermediate plunger section being of smaller cross-sectional area than the cross-sectional area of the inward and outward plunger sections, the cross-sectional area of a trap portion of the length of said passage through which the intermediate plunger section extends when the plunger member is in the receiving position being larger than the crosssectional area of the intermediate plunger section so as to form between said trap portion of the exterior of said enclosure when said plunger is moved from said receiving position to said delivery position; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufiicient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage and to permit drainage of liquid through said passage elements.

3. In an enclosure structure, such as an enclosure of an explosion-proof electric motor: a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid accumulatin in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; the cross-sectional area of a trap portion of the length of said passage being larger than the cross-sectional area of a trap portion of the length of said plunger member extending therethrough when said plunger member is in the receiving position to form between the trap portions of the passage and the plunger member a trap compartment receiving liquid from said enclosure when said plunger member is in the receiving position; an inward ejecting portion of the length of said plunger member being of a greater cross-sectional area than the trap portion of the plunger member for causing said ejecting portion to eject liquid from the compartment to the exterior of the enclosure when said plunger member is moved from; said receiving position to said delivery position; the facing surfaces of said passage and said plunger member being of circular coaxial shape; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gaplike passage elements of sufficiently small crosssection and sumcient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage elements.

l. In an enclosure structure, such as an enclosure of an explosion-proof electric motor: a lower wall member of said enclosure having an elongated passag extending from the interior to the exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; said plunger member having an inward plunger section, an intermediate plunger section and an outward plunger section, said intermediate plunger section being of smaller crosssectional area than the cross-sectional area of the inward and outward plunger sections, the cross-sectional area of a trap portion of the length of said passage through which the intermediate piunger section extends when the plung r member is in the receiving position being larger than the cross-sectional area of the intermediate plunger section so as to form between said trap portion of the passage and the intermediate plunger section held in the receiving position a trap compartment for receiving liquid from said enclosure when said plunger member is in said receiving position, and to eject liquid from said compartment to the exterior of said enclosure when said plunger is moved from said receiving position to said delivery position; the facing surfaces of said passage and said plunger member being of circular coaxial shape; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufiiciently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage elements.

5. In an enclosure structure, such as an enclosure of an explsion-proof electric motor: a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; the cross-sectional area of a trap portion of the length of said passage being larger than the cross-sectional area of a trap portion of the length of said plunger member extending therethrough when said plunger member is in the receiving position to form between the trap portions of the passage and the plunger member a trap compartment receiving liquid from said enclosure when said plunger member is in the receivin position; an inward ejecting portion of the length of said plunger member being of a greater cross-sectional area than the trap portion of the plunger member for causing said ejecting portion to eject liquid from the compartment to the exterior of the enclosure when said plunger member is moved from said receiving position to said delivery position; the passage portion of said passage facing the trap portion of said plunger member when said plunger memher is in the delivery position being of smaller cross-sectional area than the trap portion of said passage; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage elements.

6. In an enclosure structure, such as an enclosure of an explosion-proof electric motor: a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; said plunger member having an inward plunger section, an intermediate plunger length of said passage through which the intermediate plunger section extends when the plunger member is in the receiving position being larger than the cross-sectional area of the intermediate plunger section so as to form between said trap portion of the passage and the intermediate plunger section held in the receiving position a trap compartment for receiving liquid from said enclosure when said plunger member is in the receiving position, and to eject liquid from said compartment to the exterior of said enclosure when said plunger is moved from said receiving position to said delivery position; the passage portion of said passage facing the intermediate section of said plunger member when said plunger member is in the delivery position being of smaller cross-sectional area than the trap portion of said passage; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over, a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufiicient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior endof the passage and to permit drainage of liquid through said passage elements.

'2. In an enclosure structure, such as an enclosure of an explosion-proof electric motor: a lower wail member of said enclosure having an elongated passage extending from the interior to th exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; the cross-sectional area of a trap portion of the length of said passage being larger than the cross-sectional area of a trap portion of the length of said plunger member extending therethrough when said plunger is in the receiving position to form between the trap portions of the passage and the plunger member a trap compart-- area than the trap portion of the plunger member for causing said ejecting portion to eject liquid from the compartment to the exterior of the enclosure when said plunger member is moved from said receiving position to said delivery position; the facing surfaces of said passage and said plunger member being of circular coaxial shape; the portion of the enclosure having the elongated passage being formed of a duct structure removably held in said enclosure; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufiicient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage and to permit drainage of liquid through said passage elements.

8. In an enclosure structure, such as an enclosure of an explosion-proof electric motor: a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid 15 accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; said plunger member having an inward plunger section, an intermediate plunger section and an outward plunger section, said intermediate plunger section being of smaller crosssectional area than the cross-sectional area of the inward and outward plunger sections, the cross-sectional area of a trap portion of the length of said passage through which the intermediate plunger section extends when the plunger member is in the receiving position being larger than the cross-sectional area of the intermediate plunger section so as to form between said trap portion of the passage and the intermediate plunger section held in the receiving position a trap compartment for receiving liquid from said enclosure when said plunger member is in said receiving position, and to eject liquid from said compartment to the exterior of said enclosure when said plunger is moved from said receiving position to said delivery position; the facing surfaces of said passage and said plunger member being of circular coaxial shape; the portion of the enclosure having the elongated passage being formed of a duct structure removably held in said enclosure; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in all positions of the plunger member over a predetermined stroke range said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of th passage and to permit drainage of liquid through said passage elements.

9. In an electric motor of the explosion-proof type: a motor enclosure including a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; the cross-sectional area of a trap portion of the length of said passage being larger than the cross-sectional area of a trap portion of the length of said plunger member extending therethrough when said plunger member is in the receiving position to form between the trap portions of the passage and the plunger member a trap compartment receiving liquid from said enclosure when said plunger member is in the receiving position; an inward ejecting portion of the length of said plunger member being of a greater cross-sectional area than the trap portion of the plunger member for causing said ejecting portion to eject liquid from the compartment to the exterior of the enclosure when said plunger member is moved from said receiving position to said delivery position; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in the inner position of the plunger member said facing surfaces confine the flow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage elements; said plunger member having three longitudinal plunger sections, at least two of said plunger sections being of different cross-sectional area; said passage having an inward passage section forming part of said trap compartment, and an outward passage section of smaller crosssectional area through which liquid is discharged from said inward section.

10. In an electric motor of the explosion-proof type: a motor enclosure including a lower wall member of said enclosure having an elongated passage extending from the interior to the exterior of the enclosure through which liquid accumulating in the enclosure may drain to the exterior thereof; an elongated plunger member longitudinally movable in said passage between an inner receiving position and an outer delivering position; said plunger member having an inward plunger section, an intermediate plunger section and an outward plunger section, said intermediate plunger section being of smaller cross-sectional area than the cross-sectional area of the inward and outward plunger sections, the cross-sectional area of a trap portion of the length of said passage through which the intermediate plunger section extends when the plunger member is in the receiving position being larger than the cross-sectional area of the intermediate plunger section so as to form between said trap portion of the passage and the intermediate plunger section held in the receiving position a trap compartment for receiving liquid from said enclosure when said plunger member is in said receiving position, and to eject liquid from said compartment to the exterior of said enclosure when said plunger is moved from said receiving position to said delivery position; the outwardly facing surface of said plunger member and the inwardly facing surface of said passage being so shaped that in the inner position of the plunger in mber said facing surf-aces confine the fiow of fluid through said passage to gap-like passage elements of sufficiently small cross-section and sufficient passage length so as to quench ignited gases flowing from within the enclosure before they leave the exterior end of the passage elements; portions of said facing surfaces which form said gap-like passage element being of circular co-axial shape; said plunger member having two longitudinal plunger sections of different crosssectional area, on of said plunger sections having a smaller cross-sectional area than the adjacent inward plunger section and forming in its receiving position part of said trap compartment; said passage having an inward passage section forming part of said trap compartment, and an outward passage section of smaller cross-sectional area through which liquid is discharged from said inward section.

11. A drain arrangement for an enclosure as claimed in claim 3, in which the portion of the enclosure having the elongated passage is formed of a duct structure removably held in said enclosure.

12. A drain arrangement for an enclosure as claimed in claim 11, in which the removable duct structure is so shaped and mounted within the enclosure as to prevent removal of the duct structure from the enclosure and removal of the plunger member from the duct structure while the device of the enclosure structure is in its normal operating position.

13. A drain arrangement for an enclosure as claimed in claim 12, in which the duct member and the corresponding elements of said enclosure are so shaped and arranged as to permit removal of the duct member only from the exterior side of the enclosure wall.

14. A drain arrangement for an enclosure as claimed in claim 4, in which the portion of the enclosure having the elongated passage is formed of a duct structure removably held in said enclosure.

15. A drain arrangement for an enclosure as claimed in claim 14, in which the removable duct structure is so shaped and mounted within the enclosure so as to prevent removal of the duct structure from the enclosure and removal of the plunger member from the duct structure while the device of the enclosure structure is in its normal operating position.

16. A drain arrangement for an enclosure as claimed in claim 15, in which the duct member and the corresponding elements of said enclosure are so shaped and arranged as to permit removal of the duct member only from the exterior side of the enclosure wall.

17. An electric motor as claimed in claim 9, in combination with electrically actuable control means remotely operative for selectively moving said plunger member from one position to the other position.

18. In an electric motor as claimed in claim 1'7, in which said plunger member is biased to the receiving position and is actuated by the control means to the delivery position.

19. An electric motor as claimed in claim 9, in combination with electrically actuable control means remotely operative for selectively moving said plunger member from one position to the other position, said control means including means responsive to initiation of a predetermined operating position of the mechanism Within the enclosure for actuating the plunger member to perform a predetermined number of liquid discharging operations.

20. An electric motor as claimed in claim 9, in combination with electrically actuable control means remotely operative for selectively moving said plunger member from one position to the other position, said control means including timing means operative to cause the control means to actuate the plunger member to perform at predetermined time intervals a succession of predetermined liquid discharging operations.

GUSTAV E. PETIERJSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,102,034 Roller Dec. 14, 1937 30 2,349,105 Mossay May 16, 1944

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