US2224951A - Time delay switch - Google Patents

Description

Dec. 17, 1940. A. cLARKsoN TIME DELAY SWITCH 5 Sheets-Sheet l Filed Nov. 29, 1959 Dec. 17, 1940. A. cLARKsoN 2,224,951

TIME DELAY SWITCH Filed NOV. 29, 1939 3 Sheets-Sheet 2 ...LL- I @17p /z'of Hallan/z Dec. 17, 1940.

A. cLARKsoN 2,224,951

TIME DELAY SWITCH Filed Nov. 29, 1959 3 Sheets-Sheet 3 Patented Dec. 17, 1940 y 2,224,951. l f 'rma DELAY swrron Anck clarkson, Bloomingdale Township, nu Page County, Ill., assignor to Vapor Car Heating Company, Inc., Chicago, Ill., a corporation of New York Application November 29, 1939, Serial No. 306,637

8 Claims.

This invention relates to a new and improved time-delay switch for closing either single or multiple contacts after a lapse of a predetermined time period and in which the said multiple contacts may be closedeither simultaneously or in sequence at predetermined time intervals.

The improved switch closes automatically in response to electrically energized means and is so designed that it closes with a regulated rate of movement throughout its entire travel. It is opened automatically, at a substantially faster rate, by spring pressure when the said closing means is de-energized and may also be opened by mechanical means, for example, a iiuid pres, sure device, while the said electrical closing means remains energized. However, when the iniiuence of said mechanical opening means is removed, while the electrically energized closing means is effective, the switch will again move to its `closing position with the impeded rate of movement above mentioned.

While the present switch construction may be used, as above indicated, in various situations, the improvements have special utility, because of their novel cooperation with the other elements, when embodied in a fluid pressure control switch of the type shown in 'my copending application Serial No. 242,708, filed November 28, 1938. Specifically the present invention has been designed as an improvement on the switch structure' shown in the said copending application and, therefore, will be described herein as constructed and used for the same purpose, that is to saya multiple contact starter switch for the motor of a steam generating plant, for example, the blower motor of a fluid-fuel burner.

The switch comprises a unitary carriage on which is supported a plurality of separate contact fingers. It is moved to its closed position by the reiiex or contraction force of a spring which is tensioned by means which are electrically energized whenever a main switch in a main control circuit is closed. In order to insure ihe closing of the contacts in sequence at uniform time intervals the contraction of the switch closing spring is impeded, preferably by a dash-pot device constructed to accurately control the rate of the contracting movement of the said spring, there being provisions made for compensating for the gradually reduced force of the spring tension as the switch approaches its closed position. When the main control circuit is opened the starter switch will be automatically opened by means of a spring which was put under compression during vthe closing (Cl. 20o-97) movement of the switch. The said fluid-pressure means for opening the switch to stop the motor may be set to be eiective whenever a predetermined maximum fluid-pressure isv exceeded. This member of the switch assembly can be set to maintain any desired steam pressure Within certain limits, for example, 150 pounds per square inch. When the motor starter switch has been opened automatically by the rise of pressure above the predetermined limit in the steam 10 generator, the switch, upon a sudden fall of pressure in the steam generator below the predetermined limit, will close slowly so that the several contact fingers will be brought into circuit closing position at uniform time intervals.

The principal object of this invention is to provide an improved time delay switch in which the closing operation of the switch may be accurately controlled and thereby maintain a uniform rate of movement throughout its entire closing operation.

Another and more specific object is to provide an improved automatically controlled starter switch of the type briefly described hereinabove and disclosed more in detail in the specications which follow.

Other objects and advantages of this invention will be more apparent from 'the following detailed` description of one approved form of switch assembly constructed and operating according to the principles of this invention.

In the accompanying drawings:

Fig. l is a vertical section taken through a pressure controlled delay switch assembly and illustrating the improved construction ofthe present invention.

Fig. 2 is a fragmentary view in front elevation of the upper portion of the assembly, showing the pressure setting and indicating mechanism.

Fig. 3 is a fragmentary sectional view similar 40 to Fig. 1 but illustrating the starter switch in its open position. Fig. 4 is a iront elevational view of the starter switch showing the relative positions oi' the several contact lingers.

Fig. 5 is a sectional plan view taken on line 5-5 of Fig. 1, and

Fig. 6 is a wiring diagram.

The improved switch comprises a carriage or frame I0 pivotally supported intermediate its 50 endson a fulcrum pin Il which extends through a pair of ear members I2 formed on or suitably secured to a base plate I3. An insulating-block Il is suitably secured to one end portion ofthe pivoted carriage. This insulating block is prei'- 55 CFI erably formed with a plurality of grooves i5 in which are positioned the several contact ngers I6, I1, I8, I9 and 20 (Fis. 4). One end of each contact finger is pivotally attached to the block by a pin 2| of insulating material. 'Ihe other end of each contact nnger' is preferably yieldably supported between pairs of coll springs 22 and 23 which-are seated in pockets formed in the block I4 and in the insulating cross-bar l24 associated therewith. Adjustable contact: members, one for 7each contact finger, are designated I 6a, I1a, I 8a, |9a and 20a and are adapted to be accurately positioned with relation to the iix'ed contact members, hereinafter described, with which the said adjustable contacts are engaged when the switch is movedtoits' closed position. Obviously, the said contacts may be so positioned as to make simultaneous contact with the saidv cooperating fixed contact or they may ,be`po. sitioned out of horizontal alignment with each other, as shown inFig. 4, so that they will move successively into engagement with the fixed contacts at suitably spaced intervals. i' In the present disclosure the end portions ofthe contact ngers are preferably bent out of horizontal alignment, as indicated in Fig. 4, so that the operation will require less flexing of the contact lingers when they are positioned to move into successive contact with the fixed contacts above vreferred to. The timing of the intervals between the closing of the contacts of the several ngers is determined by the spaced offset relation of the movable contacts together with the speed of the switch closing movement.

The fixed contacts are designated 26, 21, 28, r29 and 30 (see Fig. 4). The said contacts 26 and 21 are supported on a metallic bracket 3| mounted on an insulating block 32 which in turn is suitably secured to the base |3 ofthe switch assembly. The other fixed contacts 28, 29 and 3|) are supported on a similar metallic bracket 33 which is secured to the said insulating block 32. The purpose of the above grouping of the fixed contacts on the separate brackets 3| and 33 will appear more clearly hereinafter from the description of the several circuits of the wiring diagram shown in Fig. 6. Each of the fixed contacts 26 to 30, inclusive, when the switch is used in a situation which requires a snap opening and closing action, is positioned between the upwardly extending legs of a horse-shoe shaped permanent magnet 34. It willbe apparent from this disclosure that when the switch carriage 6 is rocked about its pivotal axis in a switch closing direction, the contact finger I6 will be first to move into the operating range of its permanent magnet 34, whereupon this arm will be suddenly drawn downwardly (compressing spring 22) so as to engage the pair of switch contacts |6a and 26.

If the said switch isl moved at a uniform rate of speed throughout its full closing range the contacts |1a, |8a, |9a and 20a will be brought,

successively, into engagement with the xed contacts 21, 28, 29 and 39, respectively, at uniformly spaced time intervals, each movable contact being snapped downwardly by its magnet 34.

The mechanism forautomatically closing the switch comprises a solenoid coil 35 which is housed in a casing 36 suspended from the bottom face of the base plate I3 (Fig. 1). The coil is centered about a vertical guide tube 31 having a core plug 38 fitted in its upper end and secured to the upper wall of the casing 36. A movable core 39 is guided within the lower portion of the guide tube 31 and through a collar is also secured to the upper end of said cylindrical extension 42, preferably by means of a pin 45 and extends upwardll1 4through central bores 46 -ancll41 formed in thef movable core 39 and the core plug l38, respectively. The upper end of the ,push rod 44 is operatively connected with the operating arm lila of the switch carriage. This operative connection may be of any approved ,construction which makes adequate provision for/.fthe change in the angular position of the operating lever of the switch carriage during the closing and opening movements of the switch. For the purpose oi' the present illustration, a block 48'is secured to the upper end of the push rod 44. An upstanding web 49 on the block is formed with an open slot which receives a cross pin 49a fitted in the clevis end of the switch operating arm Ilia.

From the construction thus far described it will be apparent that when the starter switches are opened, as shown in Fig. 3, the movable core 39, the dash pot plunger 43, and the push rod 44 will be in their lowermost position relative to the bottom of the dash pot cylinder 56. It will also be apparent that in such position of the parts mentioned the movable core 39 will rest on the spring 4| and the said spring will be free of tension. By the closing ofthe Amain control switch I (see Fig.V 6), the solenoid 35 will be energized and the movable core 39 will be drawn,

upwardly thus tensioning the spring 4| which in turn exerts resilient lifting pressure on the push rod 44 and thereby tilts the switch carriage II) in a direction to close the several contacts thereof., Naturally the movable core 39 will be drawn upwardly the full extent of its travel substantially instantaneously with the closing of the main control switch I. Therefore, inasmuch as the push rod 44 is lifted solely by Athe tension force or contraction of the spring 4|, any variation in the voltage of the main control circuit will not ai'l'ect the rate Aoi' the switch closing movement. relative to the core 39 is limited by a stop collar 44a which is adjustably fixed on the rod 44.

'I'he rate of the switch closing movement is controlled entirely by controlling the rate of contraction of the spring 4|. This result is accomplished in the present invention by the bypassing of the uid 5| contained in the dash-pot around the dash-pot piston 43 in progressively increasing volume as the piston is drawn upwardly by the tension of the'spring 4| The proportionate increase in the volume of fluid by-passed to a position below the dash-pot piston compensates for the proportionate reduction in the tension force of the spring 4I and thereby insures the closing of the several contacts |6a to 20a, inclusive, at uniformly spaced intervals. For the purpose of illustrating one ap- The upward movement of the rod 44 proved means for impeding the contraction of spring 4| so as to obtain the results above mentioned, the inner wall 52 of the dash-pot'cylinder 50 is tapered slightly so that a proportionately larger amount of the fluid 5| will pass between the dash-pot piston and the cylinder Wall, as the said piston is drawn upwardly. In order to provide for adjustably varying the switch-closing time period the dash-pot piston is provided with a plurality of small leak holes 53 ot diil'ereht sizes, one or more of which may be opened by adjusting the position of a disc valve 54' so that a slot 55 in lthe valve will uncover the feed hole or holes desired. The said disc valve is held in position `by a spring 55a interposed between the valve and the pin I5. A ball positioned in the cylindricalextenslon 42 oi' the dash-pot piston operates to close a central port 51 during the upward movement of the dash pot piston, but is unseated by the pressure of the iiuid I during the downward movement of said piston so as to permit free passage of uid therethrough and thereby permit a relatively fast fswitch opening movement.-

When the solenoid coil 35 is deenergized; the switch carriage I6 is tilted in a clockwise direction to the switch-opening position shown in Fig.

3 by means of a coil spring 58 positioned beneath the contact end of the switch carriage so as to be compressed by the closing movement thereof. The said spring 58 is somewhat lighter than the switch-closing spring 4| and is supported on a vertically adjustable seat 56.

In addition to the spring 58 fo'r opening the switch when the control circuit through the solenoid 35 is broken, the switch mechanism is illustrated herein in connection with a pressure actuated device adapted to open the switch, without disturbing the energization of .the solenoid 35, when the pressure in the steam generating plant rises above a predetermined pressure. This pressure actuated means comprises an upper casing 59, secured to and suspended from the base I3, and a lower casing 68 between which a ilexlble diaphragm 6I is clamped. A pipe 62 leading from the source of fluid under pressure, for example, steam, is threaded into the nipple 63 oi the lower casing 60 and communicates through passage 64 with a pressure chamber 65 beneath the diaphragm 6 I. A plunger 66 seats onthe upper face of the diaphragm 6I and extends upwardly to a point beneath the switch carriage I 0. The upper end of the plunger is normally out of contact with the said switch but is adapted to press upwardly on a ball 61 secured in a suitable pocket formed `on the switch carriage body to open the switch when the steam pressure in the pressure chamber 65 rises above a predetermined pressure. The fluid pressure required to lift the plunger 66 and thereby open the switch I0 is determined by the amount of compression imparted to spring 68, 69 which are coniined between upper and lower head members 10-1l. 'I'he lower endsr of the said springs 66--69 rest on the lower head which `in turn is normally supported on the casing 59,

but is engaged by shoulders 16 formed on the lower end of the plunger 66 when the plunger is lifted or forced upwardly by the pressure in chamber 65. A movablesleeve rack 1l is movably tted on the upper end Portion of the switch opening plunger and seats in a self centering bearing 12 formed in the upper spring head 10. Compression is imparted to the said springs 68-69 to correspond to a maximum selected pressure for the pressure chamber 65 by adjusting .the sleeve rack 1| vertically. This adjust' ment is eifected by means of a pinion 13 mounted in the casing 59 to engage the teeth of the sleeve rack 1|. 'Ihe pinion shait extends out oi the casing 59 and carries at its outer end a suitable hand wheel 15 whereby the pinion 13 may be rotated to raise and lower the sleeve rack 1I and thereby vary the compression of the spring 68, 69. The pinion 13 is held in any desired adjusted position by means of clutch mechanism 16 (Fig. 2). This clutch mechanism is not illustrated specifically in this application since its speciiic construction does not aect the operation of the improvements disclosed herein, it being understood that any suitable form oi mechanism for locking the shaft 14 against accidental rotation may be used. Preferably, a pointer 11 is operatively secured to -the shaft 14 so as to indicate the pressure at which the mechanism is set to open the switch III.

Assuming now that the switch III is in its closed position, indicated inFig. 1`, and the solenoid 35 is energized: When the iluid pressure in chamberl 66 rises above a selected maximum, for example 150 pounds per square inch, the switch opening plunger 66 will be forcedupwardly against the compression of spring 66-69 to'open the switch I8. The opening movement of the'switch forces the switch closing plunger rod I4 and dash pot plunger 43 downwardly. Inasmuch as the sole- Anoid 35 remains energized the movable'core 39 remains in its upward position. Consequently the downward movement of the push rod M and dash pot 43 imparts tension to the Yspring Il whereby, in .the event that the pressure in chamber 65 is suddenly lowered or reduced, the switch I0 vwill ybe again closed automatically by the contraction of the spring 4l and this closing movement will be retarded by the action of the dash pot piston, as previously described, to effect the uniform switch closing movement. However, if the control circuit through the solenoid 36 should be broken while the switch is held open by .the pressure operated plunger 66, the spring 58 will supportthe switch in its opened position when the plunger 66 is lowered as a result of the fall of pressure in the chamber 65. It will be also apparent from the above description that l1' the main control switch I should be opened and subsequently closed while the pressure actuated plunger 66 is in its raised position, the movable core 39 of the solenoid will move to its up position and thereby put the spring 4I under tension so that it will be effective to close the switch I6 as-soon as the steam pressure in the chamber 65 is reduced below the maximum for which the pressure device is set.

The several 'conduit wires connected to the individual switch contacts, it will vbe understood, are connected with suitable terminals in a box N shown at the left of Fig.' l.

Referring' now to Fig. 6 which illustrates a simplified wiring diagram for the switch. At A is indicated a source of electric power for energizing a motor B (for example, the blower motor for fluid-fuel burner) said motor having a shunt neld C. At D, E, F, G and H are indicated a plurality of similar relays. 'I'he switch contacts of relays D to G, inclusive, are respectively opened when the relays are deenergized. The switch contacts of the relay H are normally closed when the relay is deenergized, but is opened when the relay is energized. With the main control switch I open, as shown in Fig. 6. the motor B is at rest, the electro-magnet 35 is de-energized, the movable core 39 of the electro-magnet 35 is in its lowermost position and the switch closing spring 4| is free of tension, and all of the starter switches are open. Assuming now that control switch I is moved to the completely closed position, the movable switch contact 18 will engage the two xed contacts 19 and 60, and movable contact 90 will engage the ilxed contact 9|. The electro-magnetic device Til 35 will now be energized through the following circuit: From battery A through wire 92, switch contacts 90 and 9|, wire 9,9, solenoid and wire 94 back to thebattery. The energization of the solenoid f35` results in drawing the movable core momentarily, 'whereupon the closing ofthe main 39 upwardly for its full travel, thereby tensioning the switchv closing spring 4| to impart closing pressure to the switch I0 with lthe uniform time controlled movementpreviously described. The

movable contact |66 'will ilrstr engage xed contact 26, thusv completing `a circuit energizing relay D as follows: frombattery Athrough wire 92, switch contacts 19 and 19, `wire 95, starter switch contacts 26 and la', wire 96, relayD and wires 91 and 98, back to the'batte'ry. The switch contacts of rrelay D will now be closed, thus completing a circuit through the armaturel of the motor B as follows: from battery A through wire 99, motor B, wire |00, resistances J, K and L, wire |0|, contacts of relay D and wires |02 Aand 98 back to the battery. At the same time a shunt circuit through the motor eld will be lcompleted as follows: from the wire 99, through ield C, wires |03 and |04, 4closed contacts of relay H and wires |05 and |06 to wire |0| and Athence as before, back to the battery. y

Shortly thereafter the second pair of starter switch contacts |1a and 21 will be engaged thus energizing'relay E through a circuit similar to that previously described for relay D. 'Ihis will short-circuit resistance L through wire |01 and the closed contacts of relay E. In a similar manner, vthe successive energization of relays F and Gwill successively cut out the resistances K and J, thus successively building up the current in the motor amature circuit. When the last' pair `of starter switch contacts 20a and 30 are closed, the last' r'elay H will be energized so as to open the relay switch contacts and break the shunt circuit through wires |03 and |05 around a resistance M so that this resistance will now be thrown into series with the held C of the motor so as to increase the motor speed. It will thus be seen that the simple act of closing the single control switch I will cause electromagnetic device 35, .through the resulting tension imparted to the spring Il, to eii'ect a closing of the several starter switches in properly timed relation so as to preferably build up the current 'and speed of the motor B. If switch I is opened, magnet 35 will be de-energized, whereby the spring 59 will then function to open all of the starter switches to stop the motor.

Assuming now that the switch I remains closed and the electro-magnetic device 95 remains energized, if the steam or other fluid pressure in the system builds up above the predetermined desired maximumthefpressureoperated plunger 66 will function .in a manner already described to open the starter switches and thereby stop the motor. v

It is sometimes desirable to operate the motor B for a short period at al reduced speed, for example, while warming up the system preliminary .to the normal operation. In order to do this, the switch I is moved to an intermediate position so as to engage contact 18 with xed contact 19 but ^not to engage the xed contact 90. The first pair of 'relays D and E will now be successively energized to start the motor and then cut out resistance L, but .the motor will then be permitted to runy with the resistances K and Jin the armature circuit, and without the resistance M in the eld circuit. The closing of the remaining starter switches will be ineifective to energize the relays F, G and H sincev the circuits fory these 'relays are open lat the contact 90. After the system is warmed up, the control switch I ispreferably opened to break all circuits by theopening oi' the starter switch control switch will-then be effective to Vre-energize the electro-magnet 95, whereby the starter switches will 'be closed successively at uniform time intervals in the manner first described.

I claim: l f

1. In combination with a switch,l means for automatically closing the switch comprising `an electro-magnetically operated device in a control clrcuit and operablefor its full movement immediately upon the closing of the control circuit and a coil spring operatively'engaging the switch and said electro-magnetically operated device, whereby the said spring is stretched by the operation of said device and thereby exerts closing pressure on the switch, a dash-pot for retarding the contraction of the spring to prolong the closing movement of the switch and 2. In combination with a switch, means for automatically closing the switch comprising an electro-magnetically operated device in a control circuit and operable for its full movement immediately upon the closing of the control circuit and a coil spring operatively engaging the switch and said electro-magnetically operated device, whereby the said spring is stretched by l 3. In combination with a switch, means for automatically closing the switch comprising an electro-magnetically operated device in a control circuit and operable for its full movement immediately upon the closing of the control circuit and a coil spring operatively engaging the switch and said electro-magnetically operated device, whereby the said spring is stretched by the operation of said device andthereby exerts closing pressure on the switch, means for retarding the contraction of the spring vcomprising a dash-pot having a fluid by-pass around the piston whichincreases in area in proportion to the contraction of the spring and the consequentreduction in force lexerted thereby, whereby the switch-closing movement is maintained at a uniform rate of speed for the full travel `oi' the switch, and means for adjustably varying the retarding action of the dash-pot.

i 4. In combination, a switch comprising a plurality of fixed contacts and a plurality of cooperating movable contacts, a carriage on which said movable contacts are so mounted as to engage successively with the respective fixed contacts, a spring for moving the carriage in a switch closing direction, an electrically operated device in a control circuit and adapted upon the closing of said control circuit to make said spring effective for 'closing the switch, means for controlling the rate of movement of the carriage in a switch closing direction, whereby the several contacts are closed successively at uniformly spaced intervals, and a pressureoperated device operable at a predetermined pressure for swinging the said carriage in a switch-opening direction in opposition to the switch-closing spring and for4 repositioning the said means for controlling the rate of movement of the carriage.

5. In combination, a switchcomprlsing aplurality of fixed contacts and a plurality of movable contacts, a .unitary pivoted carriage on which the movable contacts are mounted to engage successively the iixed contacts, means i'or automatically moving the said carriage in the switch-closing direction comprising an electro-magnetically operated device in a control circuit and operable for its full movement immediately upon the closing of said circuit, a coil spring operatively connecting the switch carriage and the electro-magnetically operated device, Awhereby said spring is tensioned by the operation of the electro-magnetic device to impart switch-closing movement to said carriage, means for controlling the rate of contraction of said spring, a pressure operated device operable at a predetermined selected pressure for moving said carriage in a switch-opening direction while the said control circuit remains closed, and means for automatically moving said carriage in a switch-opening direction when said control circuit is broken.

6. In combination, a switch comprising a plurality of fixed contacts and a plurality of movable contacts, a unitary pivoted carriage on which the movable contacts are mounted to engage successively the fixed contacts, means for automatically moving the said carriage in the switchclosing direction comprising an electro-magnetically operated device in a control circuit and operable for its full movement immediately upon the closing of said circuit, a push rod engaging the switch carriage, a coil spring operatively engaging said push rod and the electro-magnetically operated device, whereby said spring is tensioned by the operation, of the electro-magnetic device to lift the push rod and thereby impart 50 switch-closing movement to said carriage, means for controlling the rate of contraction of said spring, a pressure operated device operable at a predetermined selected pressure for moving said carriage in a switch-opening direction while the said control circuit remains closed, and means for automatically moving said carriage in a switchopening direction when said control circuit is broken.

7. In combination, a switch comprising a plurality of ilxed contacts and a plurality of movable contacts, a unitary pivoted carriage on which the movable contacts are mounted to engage successively the fixed contacts, means for automatically moving the said carriage in the switchclosing direction comprising an electro-magnetically operated device in a control circuit and operable for its full movement immediately upon the closing of said circuit, a push rod engaging the said switch carriage, a coil spring operatively engaging said push' rod and the electro-magnetically operated device, whereby said spring is tensioned by the operation of the electro-magnetic device to lift the push rod and thereby impart switch-closing movement to said carriage, means for controlling the rate of contraction of said spring comprising a dash-pot having a fluid bypass which increases in area. in proportion to the contraction of the spring and including means for adjustably varying the time period of the switch-closing operation, a pressure operated device operable at a predetermined selected pressure for moving said carriage in a switch-opening direction while the said control circuit remains closed, and for repositioning the dash-pot piston for the control of a subsequent switch closing operation, and means for automatically moving said carriage in a switch-opening direction when said control circuit is broken.

8. In combination, a switch comprising a plurality of movable contacts, a plurality of fixed contacts, a carriage on which the movable contacts are so mounted as to engage successively with the respective fixed contacts, a spring for moving the carriage in its switch-closing direction, an electrically operated device in a control circuit and adapted upon the closing of said control circuit to make said spring eiective for closing the switch, means for controlling the rate of movement of the carriage in its switch closing direction, whereby the several contacts are closed successively at uniformly spaced intervals,

and a pressure operated device operable at a

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