US2209721A - Switching mechanism - Google Patents

Description

July 30, 1940- D. e. TAYLOR ET AL SWITCHING MECHANISM Filed May 7, 1937 .Dabz'el er r/xae Ar Patented July 30, 1940 UNITED STATES SWITCHING MECHANISM Daniel G. Taylor and Albert L. Judson, Minneapolis, Minn.,

assignors to Minneapolis- Honeywell Regulator Company, Minneapolis, Minn., a'corporation oi Delaware Application May 7, 1937, Serial No. 141,303

11 Claims.

This invention relates to switching mechanism and more particularly to a type of switching mechanism adapted to be utilized to control a condition controlling agency such as a refrigerator or heater or analogous mechanism in response to the value of a condition to be controlled.

One object of this invention is the provision of an improved mechanism of the character above mentioned wherein a novel leverage arrangement is utilized to provide a multiplication of a relatively small movement of a condition responsive member to a relatively great movement of contact members associated therewith.

An additional object is the provision in a mechanism embodying a spring opposed to a condition responsive member of means to compensate the increased tension of the spring upon movement of the mechanism counter to the bias thereof in combination with such a leverage arrangement as mentioned in the -preceding paragraph.

A still further object is the provision in combination with such a means for compensating for the increased tension or compression of the spring and a leverage arrangement as above mentioned of means to insure a relatively rapid movement of the contacts toward and away from each other in such manner as to preclude to a substantial extent arcing between the contacts.

An additional object is the provision in combination with the mechanism previously mentioned of means whereby the operating differential of the instrument may be readily and simply varied. It should be here pointed out that in instruments of the character to be hereinafter described it is frequently desirable that provision be made whereby the condition value at which the contacts, illustratively, close be varied with respect to the condition value at which the contacts open and that such adjustment be so arranged that either value may be varied independently of the other.

An additional object of this invention is the provision of such difierential adjustment means in combination with a leverage arrangement as above mentioned and means for compensating for the increasing compression or tension of a spring as previously mentioned.

An additional and more specific object .is the provision of a switching mechanism which will be relatively simple to manufacture, sturdy and durable in construction, and reliable and efiicient in operation. 1

Further objects will in part be obvious and in part pointed out hereinafter.

The invention accordingly consists in the combination of elements, arrangement of parts, and features of construction, all as will be more fully pointed out hereafter and shown in the accompanying drawing wherein:

Figure 4 is a sectional view taken substantially along the line 4-4 of Figure 1 as viewed from the left,

Figure 5 is' a sectional view taken along the line-5-5 of Figure 1 as viewed from the left, and

Figure 6 is a perspective view showing certain details of construction.

Similar reference characters refer to similar parts throughout the several views of the drawing.

Having reference now to Figures 1 and 2, there is generally indicated at it! a casing having an aperture Ii in the base thereof. Secured to the base of easing i0 is a plate l2 having an internally threaded flange I3 adapted to project through aperture I i. Secured in turn to plate [2 is a housing M having rigidly afixed thereto a boss l5 provided with an aperture l6 therethrough. A capillary tube 51 engages boss iii in fluid tight relationship and extends to a suitable volatile fluid filled bulb (not shown).

A bellows i8 is contained within housing l4, its upper end secured to a flange 19 secured peripherally to the walls of housing M. The lower end of bellows I 8 is secured to a movable plate 20 to the inner or upper side of which is rigidly secured an operating rod or plunger 2 I. A threaded nut 22 engages the inner threaded portion of flange l3 and is provided with an aperture 23 through which operating rod 2! projects into casing it. A spring 24 is positioned between a recess 25, formed in nut 22, and plate 29 and serves normally to bias plate 28 and hence operating rod 2| downwardly as viewed in Figures 1 and 2 in opposition to the pressure of the volatile fluid admitted to housing M through aperture l6. Thus it will be understood that a change in the condition value in the space containing the bulb previously mentioned will cause the fluid therein to volatilize or liqueiy in accordance with the direction of the change causing a relative upward or downward movement of plate 20 occasioned by compression or expansion of bellows l8 and a corresponding movement of operating rod 2!.

Nut 22 is provided on its upper surface with a recess 2'! in which is seated one end of -a spring 28, the other end of which abuts a collar 29 rigidly secured to operating rod 2! in any desired manner. Thus it will be seen that spring 23 biases operating rod 24 in an upward direction against the pressure of spring 24. The purpose of spring 28 is to permit the instrument to operate under those conditions wherein a vacuum or sub-atmospheric pressure exists in housing I9. It will be understood of course the spring 25 is of greater strength than spring 28.

Operating rod 2| terminates in a pointed tip 35 positioned to engage a cup 36 carried by boss 32 held in place on a lever 31 as by a spring collar 33. Lever 31 is pivoted on a knife edge 38, knife edge 38 engaging a pair of grooves 89 in lever 37 (see Figure 3). The end of lever 37 opposit-e cup 36 carries a boss which serves as a seat for one end of a coil spring til, the other end of which is seated upon a boss 82 secured to the base of easing ID. A second lever is generally indicated at 83 and comprises a pair of extending portions M connected at their extremities as by a pin 85, and a relatively wide portion 86 (see Figure 3). Portion 86 is provided with an aperture 38 therethrough, through which boss 32 may project; thus permitting levers 3i and 93 to lie in relatively close proximity to each other. Lever 83 is mounted adjacent lever 31 and pivotally secured thereto as by a pin 98 extending through suitable apertures in extending portions 55 and upwardly turned lugs 49 which latter form an integral part of lever 37.

A pair of bracket members 50 are suitably secured to the side wall of easing l8 and formed to provide a pair of parallel extending surfaces 5|, each of Which is provided with a threaded aperture, and positioned on opposite sides of pin 85. Screws 52 provided with enlarged heads 53 extend through the above mentioned threaded apertures and are positioned for abutment with pin 45 for a purpose to be hereinafter described. Thus it will be seen that upon upward movement of operating rod 21, lever 3! is rotated about knife edge 38 against the pressure of spring 8|. Simultaneously lever 53 is moved through pivot 88 upwardly about pin 65, which through its abutment with the upper of enlarged heads 53 serves as a fulcrum for lever 83.

A pair of opposed brackets 55 and 55 are secured to the base of casing id in any desired manner as by screws or rivets 51 and extend upwardly on opposite sides of levers 81 and 88 at that end thereof adjacent spring dl. A connecting portion 58 serves as a support for knife edge 38 which is secured thereto .by screws or rivets 59. A member 591s pivotally secured as by pivots 6| and 82 to supporting members 55 and 58 respectively (see Figure 3). A slot 63 formed in member 60 is positioned for engagement with a pin carried by the distal end of an extending member 86 comprising an integral portion of lever 83. Member 80 has at its upper extremity an inwardly curved portion 18 terminating in a hook shaped portion H which engages one end of a link I2 provided at its extremities with extending lugs E3 to prevent dislodgement of the same from its engagement with hook H (see Figure 5). The opposite end oflink [2, also provided with lugs 73, engages a corresponding but oppositely formed hook 75 carried by a member 16 pivoted as by a pivot pin TI to extending portions of supporting members 55 and 58.

Member I6 carries an upwardly extending portion I8 to which is secured an insulating block I9 carrying a pair of contacts 80. A spring 8! secured to an extending post 82 provides a strain release to maintain a definite contact pressure and to preclude damage to or bending of contacts 80 and their associated contact carrying members upon engagement thereof with opposed stationary contacts 83, only one of which is disclosed in Figures 1 and 2 of the drawing. Contacts 83 are each in electrical association with one of a pair of terminals 86 mounted in an insulating block 85 secured to the upper wall of casing 10. Suitable Wires may be secured to terminals 84 and lead to any desired mechanism which it is desired to control in response to the opening or closing of contacts 88 and 83.

Member 16 is also provided with a substantially horizontally extending portion 90 formed with a right angled portion 9| through which is passed an aperture 92, (see Figure 6) adapted to have secured thereto an end of a spring 98, (see Figures 1 and 2),the other end of which is secured to a bracket which is in turn rigidly secured to the base of casing ID in any desired manner.

Thus it will be seen that upon movement of lever 83 in the manner previously described such movement is transmitted through the pin 85 and slot 63 to member 60 whence it is in turn transmitted through link 12 to member 16 and hence to opening or closing movement of contacts 89 with respect to their opposed contacts 83.

Supporting member 55 is provided with an inwardly turned portion 9! having a threaded aperture therethrough in which is positioned a screw 98 having an enlarged head '99, head 99 being so positioned as to serve as a stop to limit the travel of member 60 in such manner that when contacts 88 engage their opposed contacts 83, link 12 and knife edge 38 are in substantially vertical alignment for a purpose to be hereinafter pointed out.

Assume the parts in the position shown in Figure 2 the spring 25, the spring 5i and the spring 98 are all urging the plunger 2| downwardly and the forces exerted by the springs are additive. The springs 28 and GI act directly to move the plunger downwardly while the spring 98 acts through the link 12. The force exerted by the spring 95 is transmitted through a lever arm the length or radius of which is equal to the right angle distance between the pivot BI and the prolongation of link l2. The spring 98 also acts to maintain the contacts 80 and 83 separated. Assume now that the pressure within the casing It increases to move the plunger 2i upwardly, the lever 81 is rotated in a counter-clockwise direction about its pivot 38 and as a result the lever 48 is rotated in a clockwise direction about its pivot 85. Clockwise movement of the lever 94 causes clockwise movement of the lever 88 about its pivot 6|. This movement of the lever 68 causes right hand movement of the upper end of the link 12 and also downward movement of the link 12 and hook l5. Downward movement of the hook E5 in turn causes counter-clockwise rotation of the lever 18 to move the contacts 88 into engagement with the stationary contacts 83. These contacts engage before the lever 60 engages its stop 99 and further movement of the lever 89 into engagement with the stop 99 increases the contact pressure of the contacts, this mode of.

operation being afforded by the spring 8|.

It will be noted that as the link 12 is moved to the right the mechanical advantage of the lever 69 over the contact lever I8 decreases and is at a minimum when the link 12 is in a vertical position. This means that at the moment of making and breaking the contacts there is a maximum of force available for closing the contacts 7 mana er with a good pressure and for breaking them apart if they should stick. After the contacts have been separated the rate of movement of the movable contact increases, due to the increase in the mechanical advantage of lever Gil over lever 18 through link 12, and the force decreases, it being noted that after the contacts have once been separated not much force is needed.

As the plunger 2| is moved upwardly to close the contacts 80 and 83 in the manner pointed out above the compression or tension in the springs 24 and 4| as well-as in bellows I8 is increased and therefore they aflord a greater resistance to movement of the plunger 2|. However, as the upper end of the link 12 moves toward the right as a result of upward movement of plunger 2| the leverage arm which transmits the retarding force of the spring 34 is decreased so that when the link 12 reaches the position shown in Figure 1 where the ends of the link 12 are in alignment with the pivot 5|, the retarding force of the spring 94 becomes zero. It follows then that as the resistance of the springs 24, 4| and bellows I3 increases, the retarding effect of the spring 94 decreases and if the retarding eifect of the spring 94 is decreased at the same rate that the retarding effect of the springs 24, 4|, and bellows I8 is increased, the increase in the retarding effect of the springs 24, 4|, and bellows I8 is entirely compensated.

By reason of the above arrangement as soon as the plunger 2| is started upwardly upon an increase in pressure in the chamber I4, this pressure will continue upward movement of the plunger 2| whereupon the contacts 80 move immediately and freely into engagement with the contacts 83. If the pivot pin 45 for the lever 44 is held rigid the operating differential of the instrument will be very small, if not practically zero, by reason of the spring rate compensation feature so that the contacts 80 and 83 will be made and broken for extremely small pressure differentials aflecting the bellows l8.

In order to widen the pressure differential and provide an adjustment of the pressure differential, means are provided for allowing a'limited movement of the pivot pin 45. Assume in Figure 2 that the top stop 53 is moved upwardly so as to allow a. predetermined amount of movement of the pivot pin 45 and that the pivot pin 45 is engaging the bottom stop 53. Upon a pressure increase within the chamber H the plunger 2| rotated sumciently far in the counter-clockwise direction to cause the pin 45 to engage the upper stop '53, the lever 44 will move in a clockwise direction about the pivot pin 45 to cause countor-clockwise movement of the lever ill and the contacts 80 and 83 will thereupon be closed in the manner pointed out above. By reason of the above arrangement the spring rate compensation afforded by the spring 94 and the link 12 will not come into effect until such time as the pivot pin 45 engages the top stop and therefore the plunger 2| must move upwardly against the increasing retarding action of the springs 24 and 4| until the pin 45 engages the top stop 53. When, however, the pin 45 engages the top stop 53 the spring rate compensation feature comes into operation and causes immediate and free movement of the contacts do into engagement with the contacts 853.

With the parts in the position shown in Figure l a decrease in pressure in the casing it allows downward movement of the plunger 2| which in turn causes clockwise rotation of the lever 37. Clockwise rotation of the lever 37 causes the lever 44 to rotate in a clockwise direction about the relatively stationary pivot pin 55 until such time as the pivot pin 45 shall engage the lower stop 58. Immediate downward movement of pin 55 is prevented by allowing link '|2to pass slightly over center as it moves lever 18 into contact closing position. When pivot pin 45 engages lower stop 53 the lever 44 is rotated in a counterclockwise direction about the pivot pin 45 to cause counter-clockwise rotation of the lever 50 whereupon the contacts 80 and 83 are separated. From this it is seen that upon a decrease in pressure in the chamber H the. pivot pin 45 is moved from engagement with the upper stop 53 to the lower stop 53 before any movement of the levers 60 and 18 is had.

It follows then that by adjusting the upper stop 53 the pressure value at which the contacts 80 and 83 are caused to close is varied and likewise by adjusting the lower stop 53 the pressure value at which the contacts 80 and 83 are opened is varied. By independently adjusting these stops 53 the cut-in point and the cut-out point of the switching mechanism may be adjusted independently of each other. The greater the distance between the two stops 53 the wider the operating differential of the switching mechanism becomes. By adjusting the nut 22 the tension or compression of the spring 24 may be varied to adjust the pressure setting of the instrument.

Although for purposes of illustration one form of this invention has been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this specification and therefore this invention is to be limited only by the scope of the appended claims and prior art.

We claim as our invention:

1. A condition responsive switch comprising, a switch mechanism, a condition responsive means for operating said switching mechanism, spring means acting in opposition to said condition responsive means, an adjustable lost motion connection between said condition responsive means and said switching mechanism, means for adjusting the lost motion connection for varying the differential of operation of the condition responsive switch, and means for compensating the increased retarding effect .of the spring means.

-2. A condition responsive switch comprising, a switching mechanism, a condition responsive means for operating said switching mechanism, spring means acting in opposition to said condition responsive means, an adjustable lost motion connection between said condition responsive means and said switching mechanism, means for adjusting the lost motion connection for varying the differential of operation of the condition responsive switch, and second spring means for compensating the increased retarding effect of the first spring means. i

3. In a device of the character described comprising in combination, a lever, one end of said lever being free to move between limits, control means operatively associated with the other end of said lever, a resilient condition responsive device for first moving said one end of said lever to one of its limits and then moving said other end to actuate said control means, and means to compensate the spring rate of said resilient condition responsive device.

4. In a device of the character described comprising in combination, a first lever, one end of said first lever being free to move between limits, a'- second lever pivoted for rotation, switch means operated by said second lever, the other end of said first lever being pivoted to said second lever, a resilient condition responsive device for first moving the free end of said first lever to one of its limits and then moving said other end to rotate said second lever and actuate saidswitch, means to compensate the spring rate of said resilient condition responsive device, and means for individually adjusting each of said limits.

. 5. In a device of the character described comprising in combination, a first lever, one end of said lever being free to move between limits, a second lever pivoted for rotation, the other end of said first lever being connected to said second lever, a third lever pivoted for rotation, as link pivotally connecting said second and third levers, a movable contact carried by said third lever, a stationary contact, and a resilient condition responsive device for first moving the free end of said first lever to one of its limits and then moving the other end of said first lever causing rotation of said second lever and hence said third lever through said link, said link being in substantial alignment with the pivot for said second lever when said contacts are in closed position.

6. In a device of the character described comprising in combination, a first lever, oneend of said lever being free to move between limits, a second lever pivoted for rotation, the other end of said first lever being connected to said second lever, a thirdlever pivoted for rotation, a link connecting said second and third levers, a movable contact carried by said third lever, a stationary contact, a resilient condition responsive device for first moving the free end oi said first lever to one of its limits and then moving the other end of said first lever causing rotation of said second lever, and hence saidthird lever through said link, said link being in substantial alignment with the pivot for said second lever when said contacts are in closed position, means for varying the distance between said limits, and means'for compensating the spring rate of I said resilient condition responsive device.

lever to one of its limits and then moving the other end of said first lever causing rotation 'of said second lever and hence said third lever through said link, said link being in substantial alignment with the pivot for said second lever when said contacts are in closed position, and means for compensating the spring rate of the resilient condition responsive device, said means comprising a spring operatively connected to said third lever, said spring having no effect on said first lever when said link is aligned with the pivot for said second lever and exerting a constantly increasing force on said lever as said link is moved out of alignment with said pivot.

8. In a device of the character described comprising in combination, a first lever, one end of said lever being free to move between limits, a second lever pivoted for rotation, the other end of said first lever being connected to said second lever, a third lever pivoted for rotation, a link connecting said second and third levers, a movable contact carried by said third lever, a stationary contact, a resilient condition responsive device for first moving the free end of said first lever to one of its limits and then moving the other end of said first lever causing rotation of said second lever and hence said third lever through said link, said link being in substantial alignment with the pivot for said second lever when said contacts are in closed position, means I for compensating the spring rate of the resilient condition responsive device, said means comprising a spring operatively connected to said third lever, said spring having no efiect on said first lever when said link is aligned with the pivot for said second lever and exerting a constantly increasing force on said lever as said link is moved out of alignment with said pivot, and means for individually adjusting said limits.

9. In a device of the character described comprising in combination, a first lever, one end of said lever being free to move between limits, a second lever pivoted for rotation, the other end of said first lever being connected to said second lever, a third lever pivoted for rotation, a link connecting said second and third levers, a movable contact carried by said third lever, a stationary contact, a resilient condition responsive device for first moving the free end of said first lever to one of its limits and then moving the other end of said first lever causing rotation of said second lever and hence said third lever through said link, said link being in substantial alignment with the pivot for said second lever when said contacts are in closed position, spring means for opposing movement of said condition responsive device, and means for compensating the spring rate of said spring means and said condition responsive device.

10. A condition responsive switch comprising,

a switching mechanism, a condition responsive means for operating said switching mechanism, spring means acting in opposition to said condition responsive means, an adjustable lost motion connection between said condition responsive means and said switching mechanism, means for adjusting the lost motion connection for varying the difierential of operation of the condition responsive switch, means for compensating the change in opposing effect of the spring means, and means for adjusting the spring means for adjusting the setting of the condition responsive switch.

11. A condition responsive switch comprising, a switching mechanism, a condition responsive means for operating said switching mechanism, spring means acting in opposition to said condition responsive means, an adjustable lost motion connection between said condition responsive means and saidswitching mechanism, means for adjusting the lost motion connection for varying the differential of operation of the condition responsive switch, second spring means for comp'ensating the change in opposing effect of the first spring means, and means for adjusting the first spring means foradjusting the setting of the condition responsive switch.

DANIEL G. TAYLOR.

ALBERT L. JUDSON.

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