US2425990A

US2425990A - Control device

Info

Publication number: US2425990A
Application number: US597909A
Authority: US
Inventors: Wilbert C Buescher
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1945-06-06
Filing date: 1945-06-06
Publication date: 1947-08-19
Anticipated expiration: 1964-08-19

Description

Aug, 19, 1947.

W. BU ESCHER CONTROL DEVICE ZSheets-Sheet 1 Filed June 6, 1945 3nnentorz- WlLBERT C. BuEscHER.

I by V A m 1947- w. c. BUESCHER 2,425,990

common DEVICE Filed June a, 1945 2 Sheets-Sheet 2 3nventor:

WILBERT C. BUESCHER,

(lttorneg Patented Aug. 19, 1947 UNITED STATES PATENT OFFICE CONTROL DEVICE Application June 6, 1945, Serial No. 597,909

(Cl. 'l496) 9 Claims.

This invention relates to control devices of the type wherein an element, movable in response to variations of a, controlling condition, is arranged to actuate condition-controlling means, such as an electric switch or a pilot valve, between alternat'e positions.

While not so limited, this invention has particular utility in connection with the actuation of sequential switching means such as the fan and high-limit switches commonly employed for controlling heating apparatus of the hot-air type; an object of the invention being to provide a device-wherein overtravel of the thermally-actuated element beyond its several switch-actuating positions is unimpeded so that there is no absorption of energy from the thermal means as occurs in conventional devices of this character due to override mechanisms, tension of connecting leads, et cetera.

Another object is to provide a device of the character described wherein means are incorpo rated for preventing displacement of the switching means from its actuated position while the actuatin element is in its overtraveled position, so that jamming of the device in the reverse movement of the actuating element is prevented.

Another object is to provide a device of the character described in the preceding objects having a pair of jointly-movable and relatively-adjustable actuating elements whereby differential actuation of the switching means can be. effected.

For full understanding of the invention, and further appreciation of its objects and advantages, reference is to be had to the following detailed description and accompanying drawing, and to the appended claims.

In the drawing:

Figure 1 is a view in perspective of a control device embodying the invention;

Figure 2 is an exploded perspective view show-- ing essential parts of the device of Fig. 1; and

Figures 3 to '7 are diagrams of modified forms of the invention.

Referring first to Figs. 1 and 2 of the drawing, the numeral l I indicates a base adapted for mounting on a wall of the bonnet portion of a hotair furnace. At the back of the base is a thermostatic device, adapted to project into the furnace bonnet, comprising a helical bimetallic member l2 secured at one end to the base and at the other end to a shaft IS, the front portion of the shaft extending through an opening in the base for operating controlling means (to be described) by the rotation of the shaft in response to variations of.

the temperature to which the bimetallic member is subjected.

The shaft I3 is supported toward its outer end in an opening through the end arm of a U-shaped bracket secured to the base and is rigidly secured at its extremity to a small plate l5. This plate is adjustably attached, by a screw [6 cooperating with a slot H, to a larger plate l8 through an opening in which the shaft freely passes. Supported by the shaft l3 are thre actuating elements indicated at H], and 2|. The element [9 has a horizontal arm 22 and a dependent front arm 23 which is adjustably connected to the plate [8 by a forwardly-bent portion 24 which coopcrates with notches (not shown) in the turned-in edge 25 of the plate; the resilience of arm 23 serving to maintain it in engaging position. The ac tuating elements2ll and 2 I are similarly arranged for connection to the plate Iii-the element 2!) having a horizontal arm 26, a front arm 21, and a plate-engaging portion 28; the corresponding parts of element 2| being indicated at 29, 3B and 3!, respectively. The ends of the

front arms

23, 21 and 30 are bent around the edge of the plate to form

pointers

32, 33, 34 which cooperate with temperature indicia (not shown) on the front surface of the plate. From the foregoing it is apparent that the actuatin elements I9, 20 and 2!, due to their connection to the driving plate It, rotate with the shaft l3 in response to temperature variations of the bimetallic member [2.

Cooperable with the actuating element [9 is a member, generally indicated at 35 in Fig. 2, which is rockably mounted on a rod 36 supported at its opposite ends on the base H and a downward extension of the bracket 14. This member has a pair of

side arms

31 and 38 which extend upwardly on opposite sides of the rocking axis of the member and are spaced apart along said axis. Mounted on the underside of the member 35 is a switch 39 of the tubular mercury contact type. The top portions 40 and M of the side arms 3l--38 are arranged to engage the bracket i i and thereby limit or stop the rocking of the member, the center of gravity of the member being such that when the member is rocked in either direction from a horizontal or balanced position it tends to assume one or the other of its stopped positions. Because of the weight of switch 39 it may be necessary to provide counterbalancing weights at the top of the side arms 3138, but for the sake of clarity such weights are not shown in the drawing.

Rocking of the member 35 is effected by engagement of the elongated actuating finger 42 of element I9 with one or the other of a pair of angled shoulder-

surfaces

43 and 44 formed at the lower ends of the side arms 3138; the inner edges of the side arms being cut to form, as extensions of the

surfaces

43 and 44, curved sur--

faces

45 and 46 which, when the member is in its respective rocked positions, are on arcs closely adjacent but spaced from the path of rotation of the bottom edge of the actuating finger 42.

The actuating elements 2|] and 2| jointly cooperate with another member rockably mounted on the rod 36 and indicated at 4'1 in Fig. 2. This member is identical in construction with member 35 and comprises side arms 48-49 having stopengaging portions 50-5I, shoulders 52-53, and curved surfaces 54-55. On the underside of this member is mounted another mercury-contact switch 56. The short actuating finger 51 of ele ment 20 cooperates only with the shoulder 53 and curved surface 55, while the like actuating finger 58 of element 2| cooperates only with shoulder 52 and surface 54. In the rotation of shaft I3, differential actuation of the member 41 to its opposite controlling positions is effected due to the relative angular displacement of the

elements

20 and 2|. In practice, suitable spacers are provided on shaft I3 and rod 36 between the various parts, but for the sake of clarity these spacers are not shown in the drawing.

When the device shown in Figs. 1 and 2 is employed in connection with the operation of a hot-air furnace, the switch 56 serves to control the operation of the hot-air-circulating fan, and the switch 39 functions to interrupt the operation of the heating apparatus when the bonnet temperature reaches a predetermined high limit. The parts are shown in the drawing in the positions which they assume when the heating system is in normal operation, both the fan switch 56 and the high-limit switch 39 being in circuitclosing position.

As was mentioned above, the actuating

fingers

42 and 58 are out of actual engagement with the respective

curved surfaces

46 and 54 of members 35 and 41 (and finger 51 remote from surface 55) so that rotation of shaft I3 in either direc tion is unimpeded by the members. Material displacement of the

members

35 and 41 from the positions in whih they rest is prevented due to the fact that the finger 42, although out of engagement therewith, is closely adjacent the curved surface 46 of member 35, and finger 58 likewise adjacent surface 54 of member 41. If such preventive means were not provided, the device could become jammed by subsequent movements of the actuating fingers if the members were accidently or intentionally displaced.

The bimetallic member I2 is so arranged that with rise of temperature the shaft I3 is rotated in a clockwise direction. So if the bonnet temperature rises, the actuating finger 42 is finally brought into engagement with the shoulder 43 of member 35 and upon slight continued rotation of the finger this member is rocked to its opposite stopped position wherein the high-limit switch 39 is in open condition so that operation of the heating apparatus is interrupted. When, upon satisfaction of the room thermostat usually employed in a heating system of this character, operation of the heating apparatus is discontinued, the resultant cooling of the bimetallic member I2 effects counterclockwise rotation of shaft I3 so that the finger 5! by its engagement with shoulder 53 of member 41 rocks that member to circuit-opening position and the fan is stopped,

Upon resumption of heating, the fan is again started (at a bonnet temperature considerably higher than that at which it was stopped) by the engagement of finger 58 with shoulder 52; the desired differential of operation of the fan being effected by relative angular adjustment of the

fingers

51 and 58.

By arranging the rocking axes of the members 35 and 4! close to their finger-engaging shoulders, as in the device illustrated, full actuation of the members is effected by a small amount of movement of the fingers. The device of this invention is particularly adapted for the operation of switches of the tiltable mercury-contact type since the small possible amount of movement of the switch-controlling member (as under conditions of severe vibration) due to the clearance between the actuating element and the cooperating curved surface of the member, is not sufficient to aiTect a switch of this type; however, it is apparent that a solid-contact type switch or a jet-type pilot-valve could be substituted.

The principle of operation of the device shown in Figs. 1 and 2 can more readily be appreciated by reference to the diagrams of Figs. 3-7.

In Figs. 3 and 4, the rockable member is in the form of a single plate 6| having a, surface 62 which corresponds substantially to the path of rotation of the extremity of the actuating element 63 when the plate is in the position shown in Fig. 3, and another surface 64 which corresponds similarly when the plate is rocked to its opposite position as shown in Fig. 4. It will be observed that the element-engaging shoulders or

surfaces

65 and 66, while desirable from a practical standpoint, are not essential to the actuation of the member since the adjacent portions of the curved surfaces could serve that purpose.

In Fig. 5, the rockable member corresponds to those shown in the structure of Figs. 1 and 2 and comprises a pair of plates 6! and 68 spaced apart along the axis of rotation of the member, each plate having a curved surface, 69 and "I0 respectively, with which a pair of jointly-rotatable actuating elements, II and 12 respectively, cooperate. The back plate and associated element are shaded to distinguish them from the front plate and element. It will be observed that actuation of the member to its opposite position is effected only when the element I2 reaches shoulder I4, the member being returned to the position shown in the figure by engagement of element II with shoulder I3; differential actuation of the member is thus accomplished. Due to the angularlyspaced relation of the actuating elements, it is possible to rock the member manually between its stopped positions when the elements are in mid-position and both are then remote from their associated curved surfaces; however, it is clear that such a condition does not incur the possibility of the device becoming jammed or locked in subsequent operation-as could be the case if the curved surfaces were not provided (and, for example, if the shoulders 'I3-I4 were formed by the adjacent sides of a pair of spaced pins projectin from the base surface of the member) and the member was rocked while, for example, the parts are in the position shown in the figure.

As shown in Fig. 6, the rockable member or plate I5 has a pair of convexly-curved surfaces I6 and 11 which, when the member is in its corresponding rocked positions, conform to the path of rotation of the finger I8 of an actuating element I9 pivoted at the side of the rocking axis of the member opposite to that in Figs. 34.

In Fig. 7, the surfaces 80 and 8| of the rockable member or plate 82 conform to the path of an actuating element 83 arranged to move rectilinearly.

The embodiments of my invention herein shown and described are obviously susceptible of modification without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a control device: a member mounted for rocking movement between two positions, an element movable along a path in opposite directions from a neutral position for rocking said member to corresponding ones of said positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and cooperable with said element, said surfaces being so disposed that when the member is in a given one of said positions one of said surfaces conforms substantially to the path of continued movement of the element in the direction which caused rocking of the member to that position.

2. In a control device: a member mounted for rocking movement between two positions, an element movable along a path in opposite directions from a neutral position, means on said member engageable by a portion of said element in its movements in said opposite directions whereby the member is rocked to corresponding ones of said positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and cooperable with the element, said surfaces being so disposed that when the member is in a given one of said positions one of said surfaces conforms substantially to the path of continued movement of a portion of the element in the direction which caused rocking of the member to that position.

3. In a control device: a member mounted for rocking movement between two positions, an element having an end portion movable along a path in opposite directions from a neutral position, said member having a pair of surfaces alternately engageable by said end portion of the element in its movements in said opposite directions whereby the member is rocked to corresponding ones of said positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces cooperable with said element and formed on the member as extensions of said first-mentioned surfaces, said extension-surfaces being so disposed that when the member is in a given one of said positions one of the extension-surfaces conforms substantially to the path of continued movement of said end portion of the element in the direction which caused rocking of the member to that position.

4. In a control device: a member mounted for rocking movement between two positions, an element rotatable in opposite directions from a neutral position and having a portion engageable with said member for rocking the same to corresponding ones of its positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and cooperable with said element, said surfaces being so disposed that when the member is in a given one of said positions one of said surfaces conforms substantially to the arc of continued movement of a portion of the element in the direction which caused rocking of the member to that position.

5. In a control device: a member mounted for rocking movement between two positions, means for stopping the member in said positions, said member being so biased that when it is moved in either direction from a balanced position it assumes one of said stopped positions, an element movable along a path in opposite directions from a neutral position and having a portion engageable with said member for rocking the same to corresponding ones of said stopped positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and so disposed that when the member is in a given one of its stopped positions one of said surfaces is closely adjacent but spaced from the path of continued movement of the element in the direction which caused rocking of the member to that position.

6. In a control device: a member mounted for rocking movement between two positions, means for stopping the member in said positions, said member being so biased that when it is moved in either direction from a balanced position it assumes one of said stopped positions, an element having an end portion movable along a path in opposite directions from a neutral position, said member having a pair of surfaces alternately engageable by said end portion of the element in its movements in said opposite directions whereby the member is rocked to corresponding ones of said stopped positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member as extensions of said first-mentioned surfaces and so disposed that when the member is in a given one of its stopped positions one of said extension-surfaces is closely adjacent but spaced fromthe path of continued movement of said end portion of the element in the direction which caused rocking of the member to that position.

'7. In a control device: a member mounted for rocking movement between two positions, a pair of elements jointly movable along paths in opposite directions from neutral positions for individually rocking said member to corresponding ones of said positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and cooperable with the individual ones of said elements, said surfaces being so disposed that when the member is in a given one of said positions one of said surfaces conforms substantially to the path of continued movement of the respective one of the elements which caused rocking of the member to that position.

8. In a control device: a member mounted for rocking movement between two positions, means for stopping the member in said positions, said member being so biased that when it is moved in either direction from a balanced position it assumes one of said stopped positions, a pair of elements jointly movable along paths in opposite directions from neutral positions for individually rocking said member to corresponding ones of said stopped positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member and cooperable with the individual ones of said elements, said surfaces being so disposed that when the member is in a given one of its stopped positions one of said surfaces is closely adjacent but spaced from the path of continued movement of the respective one of the elements which caused rocking of the member to that position.

9. In a control device: a member mounted for rocking movement between two positions, means for stopping the member in said positions, said member being so biased that when it is moved in either direction from a balanced position it assumes one of said stopped positions, a pair of elements jointly movable along paths in opposite directions from neutral positions, said member having a pair of surfaces individually engageable by said elements in their movements in said opposite directions whereby the member is rocked to corresponding ones of said stopped positions, and means for preventing displacement of the member from its rocked positions comprising a pair of surfaces formed on the member as extensions of said first-mentioned surfaces and cooperable with the individual ones of said elements, said extension-surfaces being so disposed that when the member is in a given one of its stopped positions one of the extension-surfaces is closely adjacent but spaced from the path of continued movement of the respective one of the elements which caused rocking of the member to that position.

WILBERT C. BUESCHER.

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

UNITED STATES PATENTS