US2812404A - Control device - Google Patents

Description

Nov. 5, 1957 R. A. ALCOTT 2,812,404

CONTROL DEVICE Filed D60. 8, 1955 INVEN TOR. ROLLINA. ALCOTT United States Patent Ofiice 2,812,404 Patented Nov. 5, 1957 CONTROL DEVICE Rollin A. Alcott, St. Louis Park, Minn., assiguor to Minueapolis-Houeywell Regulator Company, Minneapoiis, Minm, a corporation of Delaware Application December 8, 1955, Serial No. 551,946 12 Claims. (Cl. 200-140) This invention relates to a control device and more particularly to a room thermostat. My invention concerns a novel means for control point adjustment and calibration. In responsive devices there are often problems of the switch contacts welding due to arcing at near make or break. My invention also concerns a novel means of forcing the contacts apart in case of a weld between the contacts.

An embodiment of my invention that accomplishes this desirable result consists of a switch arm pivoted relative to a base or frame with cooperating contacts being carried by the switch arm and base. The pivot pin or member determining the pivotal axis of the switch arm is guided in a cam means attached to the base and is spring biased into journaled slots in the cam means. A spring means biases the switch arm to a normal position with the contacts closed. The switch actuator applies a force to the switch arm opposing the spring bias and when the force is great enough to overcome the spring bias it will separate the contacts. If the contacts become welded to prevent their separating the actuator will then move the switch arm such that the pivot pin moves in the journaled slots in the cam means forcing movement of the contacts relative to each other and therefore cause the contacts to separate.

Therefore an object of my invention is to provide an electric switch of the slow make and break variety.

Another object of my invent-ion is to provide a means for separating welded contacts in slow make and break electric switches.

Yet another object of my invention is to provide a novel means for control point adjustment and actuation of a control device including an electrical switch.

Further objects of my invention will become evident upon inspection of the following drawings, specification and claims.

Figure 1 is an elevation of an embodiment of my invention.

Figure 2 is a partial plan view of the embodiment of Figure 1 of my invention.

Figure 3 is a plan view of a portion of the embodiment of Figure 1 of my invention.

Figure 4 is a perspective view of the portion of the embodiment of Figure 1 shown in Figure 3.

Figure 5 is a fragmentary view showing the switch arm and pivot of the embodiment of Figure 1.

Figure 6 is a fragmentary view showing the cooperating contacts as seen from the right in Figure 1.

In the drawings a base 10 has a recessed portion or chamber 11 covered by a plate 12 fitted in the base 10. A switch 13 within the chamber 11 is constructed as follows. A switch arm 15 positioned in the chamber 11 has journaled slots 16 as best seen in Figure 5, which cooperate with a pivot pin 18. The pivot pin 18 has spring extensions 19 and 20 extending at right angles to the pivot pin 18 that cooperate with the base 10 as best seen in Figure 1. A cam is attached to the base 10 in 2 the chamber 11 and has journaled slots 26 therein that cooperate with the pivot pin 18. The spring extensions 19 and 20 bias the pivot pin naled slots 26 in the cam 25.

the base 10 carries a stationary contact 30 positioned for cooperation with a contact 31 carried by the switch arm 15. A compression spring 32 engages the switch arm 15 and base 10 biasing the switch arm 15 to a position with the contacts 30 and 31 engaged. The switch arm 15 carries a bearing plate 34 positioned for cooperation wtih an actuating rod 35 journaled in the plate 12.

The switch 13 functions as follows. position as shown in Figure 1, the spring and 20 of the pivot pin 18 bias the pivot pin 18 to the top of the journaled slots 26 and bias the switch arm 15 about the pivot pin 18 counterclockwise engaging the contacts 30 and 31. Upon a displacement of the actuating rod 35 downward the switch arm 15 will rotate clockwise about the pivot pin 18 against the bias of the spring 32 and disengage the contacts 30 and 31. However, if the contacts 30 and 31 weld together and resist disengagement, then displacement of the actuating rod 35 downward will cause the switch arm 15 to rotate counterclockwise about the contacts 30 and 31 with the pivot pin 18 moving downward in the journaled slots 26. Movement downward of the pivot pin 18 in the slots 26 will cam the switch arm 15 to the right due to the angle of the slots 26. This will create a shearing action between the contacts 30 and 31 which together with the pivotal action between the contacts 30 and 31 will break the contact weld and separate the contacts 30 and 31. Upon separation of the contacts 30 and 31 the spring extensions 19 and 20 will bias the pivot pin 18 back into position at the top of the journaled slots 26. Upon a condition change with the actuating rod 35 retracted in the plate 12 the spring 32 will rotate the switch arm 15 counterclockwise about the pivot pin 18 and the contacts 3%) and 31 will again be engaged.

The condition sensing means 38 as shown in Figure 1 is supported on the base 10 by a plurality of brackets 48, an integral part of the circular plate 42. The plate 42 has a circular opening centrally located covered by a flexible diaphragm 44 which together with a dished coverplate 46 form a chamber 48 containing a temperature responsive liquid. A stud 50 attached at its head to the diaphragm 44 and positioned thereby is in screw threaded engagement with a nut 53. The nut 53 has a cylindrical portion 54 which cooperates with a bearing member 56. The bearing member 56 is attached in fixed relation to the plate 12 and base 10 by a circular member 58 attached to the base 10. The periphery of the circular member 58 is formed to provide a decorative wall plate. The bearing member 56 guides the nut 53 allowing axial movement of the nut 53. The bottom of the nut 53 cooperates with the actuating rod 35 to transmit any temperature change to the switch mechanism 13 as a change in position of the actuating rod 35.

The nut 53 has a conical surface 60 which is engaged by a spring spider member 62 as shown best in Figures 3 and 4. Extensions 63 on the spider member 62 are attached to a rotatable member 65 and positioned thereby. The spring spider member 62 exerts a force upward on the nut 53 at the conical surface 60 sufiicient that friction between the spider member 62 and the nut 53 will cause the nut 53 to be positioned angularly by the spider member 62. The relative axial position of the nut 53 on the stud 50 will determine the temperature at which the condition sensing means 38 will cause a 18 to the top of the jour- A bracket 29 attached to In a normal extensions 19 change in position of the actuating rod 35 and operation of the switch 13.

A manual adjusting member 68 is attached to the rotatable member 65 and carries an index 69 that cooperates with indicia of temperature 71 on the cover plate 4 6 for controlpoint setting.

Calibration of the control point setting of the device is obtained by holding the nut 53 from rotation and rotating the manual adjusting member 68 with the spider member slipping on the nut 53 to obtain the proper relation between indicated temperature and switch position. An electrical connector 72 connects the switch arm to-a terminal 73, and the bracket'29 is provided with a terminal 75. v

'Iihe embodiment described has particular utility as a slow action switch and thermostatic device though I do not intend to limit my invention to the embodiment shown nor to the use in thermostatic devices but to limit my invention only as defined in the appended claims.

I claim as my 'invention;

1. In a device of the type described, a base member, a switch arm, a pivot pin for said switch arm, a normally stationary contact, a contact carried by said switch arm for cooperation with said stationary contact, a first spring means biasing said switch arm to a normal position with said contacts in cooperation, a condition sensing means applying a force to said lever arm in opposition to said first spring means, a condition change pivoting said switch arm about said pivot pin, a cam attached to said base cooperating with said pivot pin, and a second spring means biasing said pivot pin to a normal position rela tive to said cam, said pivot pin movable along said cam upon said contacts failing to separate, movement of said pivot pin along said cam causing said switch arm to move said contact relative to said stationary contact.

2. In a device of the type described, a base member, a switch arm, a pivot pin forming a pivotal axis for said switch arm, cooperating contacts carried by said switch arm' and said base, spring means biasing said switch arm to a normal position with said contacts in engagement, a condition sensing means applying a force to said lever arm in opposition to said spring means, a cam attached to said base, and journaled portions in said cam means forreceiving said pivot pin, said spring means biasing said pivot pin into said journaled portions of said cam, said pivot pin movable along said cam in said journaled portions uponsaid contacts failing to separate, movement of said pivot pin along said cam moving said switch armand said contacts relative to each other.

3. In a device of the type described, a base member, a switch arm, cooperating contacts carried by said switch arm and said base, a pivot pin forming a pivotal axis for saidswitch arm, a cam attached to said base cooperating with said pivot pin, journaled portions in said cam, spring means biasing said switch arm to a normal position and said pivot pin to engagement of said cam in said journaled portions of said cam, and a condition sensing means applying a force to said switch arm oppos ing said spring means, movement of said pivot pin along said cam surface causing movement of said switch arm and movement of said contacts relative to each other.

4. In a device of the type described, a base member, a switch arm, a pivot pin forming a pivotal axis for said switch arm, cooperating contacts carried by said switch arm and said base, spring means biasing said switch arm to a normal position, a condition sensing means applying a force to said switch arm opposing said spring means, and a cam attached to said base cooperating with said pivot pin, movement of said pivot pin along said cam surface causing movement of said switch arm and move ment of said contacts relative to each other.

5. In a device of the type described, a frame, a switch arm, a pivoting means providing a pivotal axis for said switch arm in said frame, cooperating contacts carried by said switch arm and said base, spring means biasing said switch arm to a normal position, actuatin means applying a force to said switch arm opposing said springmeans, and a cam surface integral to said frame, jour..v

naled portions in said cam surface cooperating with said pivoting means, movement of said pivoting means along said cam surface causing movement of said switch arm and movement of said contacts relative to each other.

6. In a device of the type described, a frame, a switch arm, a pivoting means providing a'pivotal axis for said switch arm in said frame, cooperating contacts. carried by.

a switch arm, a stationary contact carried by said base;-

a contact carried by said switch arm for cooperation with said stationary contact, a cam means attached to said base, journaled slots in said cam means for receiving said pivot pin, a spring means biasing said switch arm to a normal position with said pivot pin in said journaled slots, a condition sensing means applying a force to said switch arm opposing said spring means, movement of said pivot pin in said iournaled slots along said cam surface causing movement of said switch arm and movement of said contacts relative to each other. 7

8. 'In a device of the type described, a base member, a switch arm, a pivot pin forming a pivotal axis for said switch arm, a first contact carried by said base, a second contact carried by said switch arm for cooperation with said first contact, a first spring means biasing said switchj arrn such that said contacts are in engagement, a condition sensing means applyinga force to said switch arm opposing said first spring means, a condition increase pivoting said switch arm about said pivot pin separating said contacts, a cam attached to said base cooperating with said pivot pin, journaled portions, apart of said cam, a second spring means biasing said pivot pin into engagement with said journaled portions of said cam, movement of said pivot pin along said cam means when said contacts fail to separate upon a condition increase, said movement of said pivot pin along said cam means causing movement of said switch arm and said second contact relative to said first contact and hence separation of said contacts, said second spring means returning said pivot pin to engagement with said journaled portions of said cam upon separation of said contacts.

9. A condition responsive device comprising a frame, a condition responsive element, a rod axially positionable by said element in accordance with condition value, a nut cooperating with threads on said rod and having cylindrical and conical outer surfaces, a manual member pivoted in said frame about an axis concentric with said nut, a spider member carried by said manual member frictionally engaging the conical surface of said nut, the angle of said conical surface of said nut such that normally there is sufiicient friction between said nut and said spider member that said nut will rotate upon rotation of said spider member, cooperating indicia on said frame and said manual member exhibiting'condition value in accor .ance with the angularly adjusted position of said nut, and a switch means actuated by the axial position of said' nut.

10. A condition responsive device comprising a frame, a condition responsive element, a rod axially positionable by said element in accordance with condition value, a nut cooperating with threads on said rod and having cylindrical and conical outer surfaces, a manual member pivoted in said frame about an axis concentric with said nut, a spider'member carried by said manual member frictionally engaging the conical surface of said nut, cooperating indicia on said frame and said manual memher exhibiting condition value in accordance with the angularly adjusted position of said nut, and a switch means actuated by the axial position of said nut.

11. A condition responsive device comprising a frame, a condition responsive element, a rod axially positionable by said element in accordance with condition value, a nut cooperating with threads on said rod, a manual member pivoted in said frame about an axis concentric with the threads on said nut, an engaging means carried by said manual member cooperating with said nut, cooperating indicia on said manual member and said frame exhibiting condition value in accordance with the axial position of said nut, and a switch means actuated by said nut.

12. A condition responsive device comprising a base, a condition responsive element, a plurality of brackets supporting said condition responsive element extended forward from said base, a stud axially positionable by said element in accordance with condition value, a nut cooperating with threads on said stud and having cylindrical and conical outer surfaces, a manual member pivoted in said frame about an axis concentric with the threads on said nut, a spring spider member carried by said manual member frictionally engaging the conical surface of said nut, the angle of said conical surface of said nut being of a value that normally the spring bias of said spider member creates suflicient friction between said nut and said spider member that said nut will rotate upon rotation of said spider member, portions of said manual member extending radially beyond said brackets but allowing rotation of said manual member between said brackets, an adjusting member carried by said portions of said manual member, cooperating indicia on said adjusting member and the outer surface of said condition sensing element exhibiting condition value in accordance with the angularly adjusted position of said nut, and a switch means actuated by the axial position of said nut.

References Cited in the file of this patent UNITED STATES PATENTS Dillman et al. Apr. 30, 1940 Weber et al. Nov. 15, 1949 Fuchs Jan. 3, 1950

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