US1972675A - Thermostatic switch - Google Patents

Description

Sept. 4, 1934.

F. E. BEI-:BE

THERMOSTATIC SWITCH Filed March 4. 1931 Jig. f

Patented A' Sept. 4, 1934 UNITED STATES THEBMOSTATIC SWITCH Fredrick Earl Beebe, Willowick, Ohio, assignor to George E. Beach, Cleveland, Ohio Application March 4, 1931, Serial No. 520,006

10 Claims.

The present invention relates to a switch and more particularly to a fast, positive snap action switch adapted for use with a thermostatic or other automatic control, such as is shown in my co-pending U. S. application Serial No: 217,635.

More particularly, the present mechanism provides a housed-in structure in which two spring contact members are employed, one of them bef ing supported during closed contact to provide positive contact under tension.4 Provision is made so thatA the member `will move during the breaking operation, to the point where the other member snaps to its releasing position, thus assuring a quick positive breaking of the contacts. To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following de- 20 scrption set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various vmechanical forms in which the principle of the invention may be used.

In said annexed drawing:-

Fig. 1 is a vertical sectional view showing the present mechanism in connection with automatic operating means; Fig. 2 is a top plan view of the switch mechanism without the bellows; Fig. 3 is a transverse section through the switch housing showing the mechanism; Fig.r 4 is a section through a spool and plunger constituting part of the switch mechanism; and Fig. 5 is a vvertical sectional View of the switch with a modified form of operating means.

The present switch consists of a circular base plate 1 having a central aperture 2 and a similar cover plate 4 with a central aperture 3, these plates being spaced apart by means of a cylinder 5 forming with the plates the housing and the parts being held together by bolts 6 vwhich pass through the plates and secure them to the cylinder. Mounted on the base plate is a U-shaped member 10 having slots 11 near the top of the uprights 9 of the U, this member 10 being bolted or screwed to the base plate and being spaced off center asbest shown in Fig. 2. Mounted in the two grooves 11 is a spring contact strip 12 having a contact button 13 thereon, this strip 12being slightly longer than the normal width between the uprights 9 so as to take a curvedposition, either that shown in full or in dotted lines in Fig. 1.

Secured to the base plate by means of a screw 15 is a second spring contact arm 16 which has a U-bend and which is also provided with a contact button 17 spaced from and in complementary relation to the button 13,this spring arm being normally in the position shown in Fig. 3 and spaced away from the contact strip when the 60 latter is in its open position which is that shown in full lines in Fig. 1. Mounted through the apertures in the base and cover of the housing is a plunger tube 20-which is preferably exteriorly threaded throughout the central portion of its extent and which has` mounted thereon a spool 21 which, of course, is likewise threaded so as to be adjustable along the plunger tube. A

As best illustrated in Fig. 3, the recess in the spool between the ends 22 and 23 thereof receives 70' the contact strip 12 and the contact arm 16 so as to engage therewith and move them through movement of the plunger. When the spool is moved downwardly, the contact strip will be forced past the center point, the uprights 9 spring- 75 ing suiciently to allow movement, and will then l snap down into the position shown in dotted lines in Fig. 1 at which point it rests against the contact arm which, in this position, is supported by the lower shoulder 23 of the spool and thus the 80 two contact points areV held in engagement by the tension of the contact striprdue to the fact that the contact arm is held against further downward movement. When ,the plunger and spool are moved upwardly, the contacts will be maintained in engagement until the contact stripr is moved past the center or releasing point at which time it will snap upward into the position shown in full lines in Fig. 1, thus breaking the contact between the contact points and the upper shoulder 22 of thevspool will contact with the cover of the switch housing and prevent further movement of the spool before the lower portion of the spool can raise the contact member sulficientl'y to force it into engagement with the con- 95 tact strip. In this way a fast, positive break is provided between the two contact members but these are held in contact during the movement to the breaking point so that there is no tendency for the contacts to separate until the snap action takes place. In closing. the contacts the same sn'ap action is obtained but when the contact strip 12 is moved so as to force it into its lower position, the spring contact arm 16 is then supported by the lower shoulder 23 to prevent its downward 105 movement.

This switch mechanism is particularly adapted for use with a thermostatic or other automatic operating mechanism such as that shown in my co-pending application previously referred to.

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The operating mechanism ,consists of two brackets 30 and 40 mounted on the cover 4 and base plate 1, respectively, each bracket carrying a thermostatic bellows 41 and 42. -These two bellows are provided with actuating means which will operate the plunger tube 20 by contacting with the ends thereof which extend through the cover and base plate. .The two bellows also interact on each other through the medium of a plunger rod 43 which passes through the hollow plunger tube 20 of the switch. The switch is caused to function by means of the actuating mechanism as follows: The lower bellows 42 is connected to the boiler of a refrigerating unit through a tube 47 and a heat responsive'cylinder 48. When the boiler becomes heated, expansion forces a fluid into the bellows 42 which then moves upwardly forcing the spool 21 also to move in an upward direction. At this time, the spring strip 12 will be in its lower position, indicated by dotted lines in Fig. 1, and ismaking contact with the spring contact arm 16,

-so as to complete a circuit, and thus heat the boiler. The upward movement of the spool 21 forces lthe ange 23 against the contact arm and the Contact strip, causing the latter to spring instantaneously into its upper position where it is bowed away from the contact arm 16, and has broken the circuit. The spring contact arm 16 isffiexible and permits the aforesaid movement, but the spool is prevented from giving this arm any further upward movement, by which contact might again be made with the strip 12 in its upper position, by the ange 21 which stops against the cover plate 4.

The expansion of the lower bellows, while it has been breaking the circuit through the upward per bellows 42, which is known as a frost bellows,A

has been in a contracted position due to the following phenomena: The frost bellows is connected: through the tube 54 and the cylinder 55 with Vthe frost chamberef the refrigerating system. This frost chamberxhas become warm previous to the addition of the new supply of electrical heat to the boiler and the water with which Some time after the y new supply of heat has been fed to the boiler and cut off again by the expansion ofthelower bellows, cold commences to be generated inthe frost chamber and this causes ice formation in `the cylinder 55, the expansion of the ice forcing water into the upper bellows 41 and causing this to expand. The rising bellows forces the plate 46 vbetween the'latches 52 and spreads these out of engagement with the plate'51. The platei 51 is now free to lmove ldownwardly under the Leraars yoke 50 against the end of the plunger tube 20 to move the upper ange 22 of the spool against the spring strip 12. The uprights 9 of the U- shaped member 10 give su'iciently to permit the strip to reverse its curvature and to spring suddenly into contact with the arm 16, the contact buttons 13 and 17 completing an electrical circuit. Current will now A.flow to an electrical heater with which thev boiler is equipped, thusheating the boiler and the cylinder 48 which will again 85 cause iiuid to expand the lower bellows 42 and the cycle of operation begins anew.

A A modified form of acutating means for the switch is shown in Fig. 5. In this modification, the switch elements are essentially the same as is shown in Fig. l, but the manner of conveying a thermostatic effect thereto is slightly differ-ent, the same being intended for use with compressor type refrigerating systems where delayed action is not required as in the case of systems of the intermittent absorption type. In place of the upper and lower bellows shown in other views of the drawing, a diaphragm 56 is connected to the frost chamber of the refrigerator by means of a coupling 57.` As the frost chamber cools down, ice is formed therein and the expansion of the ice'forces water into the diaphragm 56 which thereupon expands and forces the hollow plunger tube 20 upwardly, pressing y the spool 2l against the spring strip 12 and caus- 105 ing this to spring away from the contact arm 16. The electrical circuit is thus broken and heat ceases to be supplied to the boiler of the refrigerating system. When the frost chamber commences to warm up due to the fact that refrigerant gas is no longer being given oi by the boiler, the ice melts and permits the liquid to flow out of the diaphragm 56, whereupon the spring 58 surrounding the tube 20 actson the flange 59 to' pull the tube 20 downward and with it the flange 115 22 of the spool 21 which causes the spring strip 12 to snap downward into contact with the spring arm 16. This compl-etes the electrical circuit through the buttons 13 and 17 and causes current again to ow ythrough a heater and warm the boiler, whereupon the frost chamber again commences to become cold and the cycle is repeated.f The buckle switch hereinabove described is particularly adapted for use in thermostatic control devices and permits the supply of electric cur- 125 rent to be turned 0E and on accurately as the needs of the system demand. The spring strip insures .that both the making and breaking of the circuit will be practically instantaneous and the snap action resulting from the use of a bowed spring strip prevents arcing orburning. While my new and improved switch is particularly useful in connection with thermostatic control means, it may also be used wher-everI intermittent operation of apparatusv is to be regulated. 135

Other modes of applying the principle of my invention may be employed instead of the one "ing-positioned to acton said opening and closing means in a line substantially coinciding with the direction of motion of said thermostatically sensitive means, said thermostatically sensitive means being unattached to said opening and closing means and means adapted to impart a snap action to said openingand closing means.

2. A thermostatic control mechanism comprising an electrical switch, thermostatically sensitive means adapted to actuate said switch, said thermostatically sensitive means being positioned so that the line of motion thereof substantially coincides with the line of motion of said switch, said thermostatically sensitive means being unattached to said switch, and means adapted to render the opening and closing of said switch instantaneous.

3. A thermostatic control mechanism comprising a spring strip and a spring contact arm, a-spool mounteclon a shaft and having flanges positioned to engage said spring strip and said spring contact arm and thermostatically sensitive means adapted to move said anges into engagement with said spring members.

' 4. A thermostatic control mechanism comprising a spring strip maintained in a bent position under tension, a spring contact arm adapted to make electrical contact with said spring strip, a Spool having anges positioned to engage said spring members, and thermostatically sensitive means adapted to move said spool to reverse the curvature of said spring strip and make or break spring members, and thermostatically operated bellows adapted to move said spool to reverse the curvature of said spring strip and make or break said electrical contact.

6. A thermostatic control mechanism comprising a spring strip maintained in a bowed position between supports spaced closer together than the length of said strip, a spring contact arm adapted to make electrical contact with said spring strip, a spooll having anges positioned to engage said spring' members, a shaft inserted in said spool, and bellows attached to said shaft adapted to move said spool.

7. A. thermostatic control mechanism comprising an electrical switch, a spring strip in said switch adapted to snap into contact and out of contact with a spring contact arm, a bellows adapted to open said switch and another bellows adapted to delay the closing of said switch.

8. In a tliermostatic control mechanism the combination which comprises a spring strip, a spring contact arm, and thermostatically operated means forcing said spring strip to spring into contact and out of contact with said spring contact arm, said spring strip being unattached to said thermostatically operated means.

9. In a thermostatic control mechanism, the combination which comprises a spring strip maintained in a bowed position under tension, a spring contact arm adapted to make contact with said spring strip, and means adapted simultaneously to reverse the curvature of said spring strip and to bring said contact arm into contact with said spring strip when the latter is reversed, said means being unattached to said spring strip.

10. In a thermostatic control mechanism, the combination which comprises a spring maintained in a bowed position under tension between supports spaced closer together than the length ofsaid strip, a spring contact arm adapted to make electrical contact with said spring strip, and a spool having anges positioned to engage said spring members.

FREDRICK EARL BEEBE.

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