US3843947A

US3843947A - Sequencing control module

Info

Publication number: US3843947A
Application number: US00338368A
Authority: US
Inventors: H Mcintosh
Original assignee: Robertshaw Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1973-03-05
Filing date: 1973-03-05
Publication date: 1974-10-22
Anticipated expiration: 1991-10-22

Abstract

A sequencing control module including first and second controlled device sets having a driven element mounted adjacent thereto and shiftable to a first position to actuate the first set and to a second position to actuate the second set. Electrical drive means is provided for controlling movement of the driven element and first and second control switches are connected in parallel and with the drive means and are disposed adjacent the driven element. Actuating switches are connected in series with the control switches and a control switch actuating device is carried by the driven element and is operative upon the driven element being shifted to its first position to deactuate the first control switch and upon the driven element being shifted to the second position to deactuate the second control element.

Description

United States Patent [1 1 [111 3,843 947 McIntosh v Oct. 22, 1974 [54] SEQUENCING CONTROL MODULE Primary Examiner-Harold Broome [75] Inventor: Harold A. McIntosh, South Attorney, Agent, or Firm-Fulwider, Patton, Rieber,

Pasadena, Calif. Lee & btecht [73] Assignee: Robertshaw Controls Company, [57] ABSTRACT Richmond, Va. A sequencing control module including first and sec- 0nd controlled device sets having a driven element [22] Flled' 1973 mounted adjacent thereto and shiftable to a first posi- I21 1 Appl. No: 338,368 tion to actuate the first set and to a second position to actuate the second set. Electrical drive means is provided for controlling movement of the driven element 5" 337/126 200/153 and first and second control switches are connected in 58] ia C 166 SD parallel and with the drive means and are disposed ad- 337/3l1 141 f 335/126" jacent the driven element. Actuating switches are connected-in series with the control switches and a control switch actuating device is carried by the driven [56] References Cited element and is operative upon the driven element UNITED STATES PATENTS being shifted to its first position to deactuate the first 2,658,123 11/1953 Stoeser 335/126 control switch and upon the driven element being lllyobods ettaLl ZOO/2106035813 shifted to the second position to deactuate the second a ares e a.

Illlllllll control element.

6 Claims, 4 Drawing Figures SEQUENCING CONTROL MODULE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device which may be utilized for sequentially actuating a series of electrical devices.

2. Description of the Prior Art Various sequencing systems have been provided for actuating electrical devices at predetermined intervals of time and such devices have been proposed which include a driven cam formed with a plurality of spaced apart cam surfaces which are disposed in staggered relationship with respect to switch actuating members to thus progressively actuate such switches as the cam is shifted to its various positions. Such devices have been proposed wherein movement of such cams is controlled by thermally expansible rods'h'avinga plurality of heat motors disposed in heat exchange therewith and selectively actuatable to provide different quantities of heat to the rod to thus shift the driven cam different distances depending on the number of heat motors actuated at any one particular time to thereby actuate different ones of the switches. Systems of this type suffer the shortcoming that fluctuations in the level of power from the power source results in fluctuations in the heat levels of the heat motors energized thus causing unwanted and erratic fluctuations in thermal expansion of the rods and providing for erratic shifting of the cam and consequent erratic actuation of the controlled devices. Further, efforts have been made to provide electrical control systems which incorporate thermostatic delay switches which provide for time delays between actuation of the various switches in the system. Devices of this type suffer the shortcoming that they are relatively expensive to manufacture and delay time. between actuation of different switches in the system is difficult to control with any degree of precision.

SUMMARY OF THE INVENTION The sequencing control module of the present invention is characterized by a driven element which is shifted to a plurality of different positions to operate different numbers of electrical devices at each position. Further, the driven element is operative to open respective control switches at each respective position to thus discontinue current to a driving means to thus discontinue movement of the driven element and maintain it in the position selected.

The objects and advantages of the present invention will become apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawing.

DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of a sequencing control module embodying the present invention;

FIG. 2 is a transverse sectional view, in enlarged scale, taken along the line 2-2 of FIG. 1;

FIG. 3 is a schematic view similar to FIG. 1, but depicting the module in a difierent position; and

FIG. 4 is a partial schematic view similar to FIG. 1 and showing the control module in a third position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The sequencing control module of the present invention includes, generally, a housing 11 having five sets of switches 13, 15, l7, l9 and 21 mounted thereon and controlled individually by means of a driven cylindrical cam rod 23. Positioning of the cam rod is controlled by means of a thermally expansible rod 25 having a resistance wire 27 wrapped thereon, such wire being connected with a pair of parallel connected control switches 29 and 31. The actuating switches 29 and 31 are in turn connected in series with respective first and second stage position switches, generally designated 33 and 35. Closure of the first stage control switch 29 energizes the resistance wire 27 to heat the rod 25 to cause such rod to grow in length thus enabling the driven cam 23 to move to the left thereby closing the first three

switches

13, 15 and 17, as well as opening the first stage control switch 33 thereby periodically discontinuing heating of the resistance wire 27 to enable the rod 25 to cool and cause the driven cam 23 to seek a position maintaining only the first three switches l3, l5 and 17 closed while the

switches

19 and 21 remain open. Subsequently, the second stage control switch 31 may be closed to energize the resistance wire 27 through the second stage position switch 35 to maintain the resistance wire 27 energized until the driven cam 23 is shifted sufficiently far to the left to close all five controlled switches 1321 and to open the second stage position switch 35 periodically thereby maintaining a heat balance in such resistance wire sufficient to maintain such cam 23 in its second position.

The cam rod 23 may have a configuration similar to that disclosed in US. Pat. application Ser. No. 303,535, filed Nov. 3, 1972, and assigned to the assignee of the instant application. Such driven cam 23 is formed with a plurality of major diameter cylindrical cam surfaces 41 having their right hand ends tapered inwardly to form frustoconical actuating cam surfaces 43 terminating at respective minor diameter rod portions 45. The cam surfaces 43 are arranged in staggered relationship with respect to the respective switches 15-21 to cause such switches to be closed sequentially as the cam rod 23 is shifted gradually to the left.

The left hand end of the cam rod 23 is formed with a plurality of side-by-side peripheral index grooves 49 which define indentations for selective receipt of an index plunger 51 urged into such indentations by means of a biasing spring 53. The index plunger 53 is so positioned that it is engaged in the third groove from the left when the cam rod 23 is in the position shown in FIG. 1 with the three

switches

13, 15 and 17 closed and is positioned in the extreme right hand groove 49 when the cam 23 is in the position shown in FIG. 3 with all five switches l3-2l closed.

The first stage position switch 33 includes a stationary contact 55 formed by the rounded end of an electrically conductive set screw 57 screwed into a threaded bore 59 in an electrically insulative bracket 61 mounting such screw from the housing 11. An electrically conductive wiper 5 is mounted on such bracket 61 to wipe against the surface of the screw 57 and is connected with a lead 69 leading to the first stage control switch 29. The movable contact 73 of the first stage position switch 33 is mounted from a resilient electrically conductive common blade 75 which is carried from an 3 electrically insulative block 77 mounted from the housing 11 by means of a pivot pin 79. Such mounting block 77 is biased in a counterclockwise direction by means of a torsional spring 81.

The second stage position switch includes a first contact 85 mounted intermediately on the common blade 75 and a second contact 87 mounted intermediately on a flexible blade 91. Mounted from the lower extremity of the second stage contact blade 91 is a pusher pin 95 which projects freely through a bore96 (FIG. 4) formed in the free extremity of the common blade 75 to be engaged by a driving cam 97. A stop pin 98 is mounted adjacent the lower end of the common blade .91 to limit leftward travel of the blade end to cause the second stage position switch 35 to openwhen the cam 23 is in its second'position (FIG. 4).

The thermally expansible drive rod 25 acts through a drive linkage, generally designated 101, and including abase channel 103 having a drive arm 105 pivotally mounted from one extremity thereof by means of a pivot pin 107. Mounted from the opposite extremity of such base channel 103 by means of a pivot pin 109 is an intermediate link 111 projecting parallel to the drive arm 105. The free extremity of the intermediate link 11 1 is connected intermediately with the drive arm 105 by means of a diagonal link having its opposite ends mounted on pivot pins 113 and 115. The lower extremity of the intermediate link 111 is connected with the upper end of the arm 105 by meas of a tension spring 117 thus developing a mechanical advantage tending to draw the upper extremity of such arm to the left, such tendency being limited by means of the thermally expansive rod 25 which is connected on its right hand end to an end flange 121 formed in the base channel 103 and on its left hand end to the lower extremity of the intermediate link 111.

The upperextremity of the drive arm 105 is formed with a circular shaped spacer 127 received loosely in an oversized circumferential groove 129 formed in the driven cam 23 to thereby provide a predetermined amount of play between such arm and cam. Also projecting upwardly from the upper end of the drive arm 105 is the coupling arm 97 which projects beyond the cam rod 23 and engages the end of the push pin 95 carried from the blade 91 of the second stage position switch 35.

The switches 13-21 are in the form of electrically conductive resilient blades 135 and 137 (FIG. 2) mounted cantileverally from the housing 11 and having respective contacts 139 and 141 mounted intermediately thereon. In practice, the sequencing control moduleof the present invention may conveniently be utilized to control a plurality of heating elements in a forced air furnace to provide for sequential energization of the heating elements thus avoiding loading the power source with all such heating elements at the same instant to reduce the start-up load on such source. In such an arrangement, the heat motor resistor 27 on the drive rod 25 may be connected with a transformer 141 by means of

leads

143 and 145 and parallel circuits formed by the actuating switch 29, lead 69 and position switch 33. The other branch of the parallel circuit is formed by the actuating switch 31, lead 151 and second stage position switch 35.

In operation, the actuating switches 29 and 21 may be incorporated in a thermostat 155 which senses the area heated by the furnace incorporating the heating elements connected with the respective controlled switches. The control switch 13 may be connected with the furnace blower and it will be appreciated that such switch is disposed in relationship to the cam rod 23 to have its blades 135 and 137 disengage the associated cam surface 41 upon initial leftward movement of the cam rod 23 as shown in FIG. 1 to energize such blower to commence blowing air over the heating elements controlled by the remaining switches 15-21 to thus prevent overheating of such heating elements upon energization thereof. Thus, when the thermostat 155 calls for heat, the actuating switch 29 will close thus completing a circuit from the top end of the transformer 141 through the switch 29, lead 69 and first stage position switch 33 up through the common switch blade through lead 145, resistance wire 27 and back through lead 143 to the bottom end of the transformer 141. Consequently, the thermally responsive rod 25 will be heated to grow in length thus enabling the upper end of the intermediate link 111 to move to the left as the upper end of the drive arm is drawn to the left by means of the tension spring 117. As described hereinbefore, leftward movement of the drive cam 23 first shifts such cam to the left thus disengaging the index plunger 51 from the leftmost groove 49 to reengage such plunger with the groove 49 second from the left. Concurrent therewith, the cylindrical cam surfaces 41 associated with the blower switch 13 and first heating switch 15 are shifted from between the associated switch blades to assume the broken line position shown in FIG. 2 with the associated contacts 139 and 141 in engagement with one another. Thus, a circuit is completed through the furnace blower and through the first stage heating element.

Continued growth of the thermally responsive rod 25 continues movement to the left of such drive cam 23 to again retract the index plunger 51 to enable the cam 23 to be shifted further to the left thus shifting the cam surface 41 associated with the third switch from between the associated switch blades and 137 to enable the free endsof such blades to move toward one another thus carrying the respective contacts 139 and 141 into engagement with one another and completing a circuit through the second heating element of the furnace.

The set screw 57 forming the first stage position switch stationary contact 55 is so adjusted in the mounting bracket 51 that leftward movement of the cam 23 to the position shown in FIG. 1 causes the coupling arm 97 to raise, to engage the push pin 95 and urge the second stage contact blade 91 counterclockwise as shown in FIG. 1 against the bias of the torsion spring 81 to thus lift the first stage movable contact 73 off the stationary contact 55 when the driven cam 23 is in the position with the first three controlled

switches

13, 15 and 17 closed and the

remaining control switches

19 and 21 open. Opening of the first stage position switch 33 opens the circuit to the resistance wire 27 thus allowing such wire to cool and the thermally responsive rod 25 to shorten thus rotating the control arm 101 slightly clockwise to enable the spacer 127 to move to the right slightly within the groove 129. Such shifting to the right of the free end of the control switch actuating arm 97 enables the free end of the second stage position switch blade 91 to move slightly to the right and causing the mounting switch block 77 to rotate counterclockwise on the pivot pin 79 to thus close the first stage switch 33 thereby reenergizing the resistance wire 27 to again heat the thermally responsive rod 25 and cause the drive arm 105 to again rotate slightly counterclockwise to again open the first stage position switch 33.

Thus, any surges in power from the transformer 141 which may cause the resistance wire 27 to heat to a higher level will merely cause the first stage position switch to cycle open and closed at a more rapid rate and will not result in altering the position of the driven cam 23 and consequent unwanted actuation of the controlled switches 19 and 21.

However, if the room temperature being controlled continues to drop the thermostat 155 will initiate closure of the second stage actuation switch 31 to complete a circuit from the top end of the transformer 141 through such actuation switch, lead 151, second stage position switch blade 91, through

contacts

87 and 85, through common blade 75, lead 145, resistance wire 27 and back through lead 143 to the bottom end of the transformer 141. Consequently, the resistance wire 27 will be energized through the second stage position contact 35 thus enabling the upper end of the drive arm 105 to continue leftward movement of the driven cam 23 beyond the position at which the first stage position switch 33 opens to the position shown in FIG. 3 where the lower extremity of the common blade 75 engages the stop pin 98.

Further movement of the upper extremity of the drive arm 105 will cause the coupling arm 97 to push the second stage position switch blade 91 further to the left thus opening such second stage switch 35 as shown in FIG. 4 thereby deenergizing the resistance wire 27 and discontinuing leftward movement of the cam rod 23. Deenergization of the resistance wire 27 will enable such wire to cool and the thermally responsive rod 25 to shorten thus enabling the upper extremity of the drive arm 105 to shift slightly to the right within the play provided within the groove 129 thus enabling the second stage position switch 35 to close and again energize the resistance wire 27. As described hereinabove, cycling in this manner will be continued until such time as the second stage switch 31 is open. If the first stage switch 29 remains closed, the subject sequencing module will return the controlled cam rod 23 to the position shown in FIG. 1 to maintain the first stage heating elements connected with switches and 17 energized while maintaining the second stage heating elements connected with the

switches

19 and 21 deenergized. When the room is heated to a temperature above the target temperature thev first stage actuating switch 29 will be opened thereby enabling the thermally responsive rod 25 to cool and bring the cam rod 23 to its full right hand position depicted in broken lines in FIG. 1 thereby opening the

switches

13, 15 and 17 to deenergize all the furnace heating elements and associated blower.

From the foregoing it will be apparent that the control module of the present invention provides an economic and reliable means for controlling sequential actuation of controlled devices.

Various modifications and changes may be made with regard to the foregoing detailed description without departing from the spirit of the invention.

What is claimed is:

1. A sequencing control module comprising:

a housing;

first and second controlled device sets spaced apart a selected distance on said housing, said first controlled device set including first and second contacts mounted from said housing, said second contact being mounted for movement into engagement with said first contact;

a driven element carried from said housing and shift able to a first position to actuate said first controlled device set and to a second position to actuate said second controlled device set;

electrical drive means mounted on said housing, coupled with said driven element, and including first and second circuit means and further including a lever arm shiftable in one direction to shift said driven element to said one position and a switch control arm projecting therefrom and means coupling said switch control arm with said second contact;

first and second position control elements mounted on said housing for selectively opening said first and second circuit means;

control element actuating means coupled with said drive means and operative upon shifting of said driven element to said first position to engage said first control element to open said first circuit means and upon shifting of said driven element to said second position to engage said second control element and open said second circuit means; and

control means for selectively completing said first and second circuit and including coupling means loosely coupling said driven element with said lever arm to provide a sufficient amount of play between said lever arm and element when said element is in said first position to enable said control element actuating means to engage said first control element to open said first circuit means while said driven element remains in said first position. 2. A sequencing control module as set forth in claim 1 wherein:

said driven element is formed with first and second spaced apart detents and said module includes bias means urging said driven element toward said second position; and snap acting means including a plunger engagable in said first detent to resist shifting of said driven element to said first position and engagable in said second detent to resist shifting of said driven element to said second position and biasing means urging said plunger into said detents with a predetermined force to provide a selected amount of resistance to shifting of said driven element. 3. A sequencing control module as set forth in claim wherein: said drive means includes biasing means urging said driven element toward said second position, a temperature responsive expansive rod normally resisting shifting of said driven element toward said second position and heat motor means disposed in heat exchange relationship with said rod. 4. A sequencing control module comprising: a housing; first and second controlled device sets spaced apart a selected distance on said housing, said first control element including a switch body pivotally mounted from said housing and first and second electrically conductive blades projecting there- 7. from, said second blade-being resilient and said moveable contact being mounted on said first blade, said second control element further including a first contact mounted from said first blade and a second contact mounted from said second blade and normally engaged with said first contact and bias means urging rotation of said body to normally maintain said stationary and moveable contacts in their closed positions;

a driven element carried from said housing and shiftable to a first position to actuate said first controlled device set and to a second position to actuate said second controlled device set;

' electrical drive means mounted on said housing, coupled with said driven element, and including first and second circuit means;

first and second position control elements mounted on said housing for selectively opening said first and second circuit means; and

control element actuating means coupled with said drive means and operative upon shifting of said driven element to said first position to engage said first control element to open said first circuit means an upon shifting of said driven element to said second position to engage said second control element and open said second circuit means, and further including means carried by said driven means and engageable with said second blade and coupling means operable upon said drive means shifting said driven element to said first position to disengage said moveable contact from said stationary contact and upon shifting of said driven element to said second position to disengage said second contact from said first contact.

5. A sequencing control module as set forth in claim 4 wherein:

said driven element is formed with first and second spaced apart detents and said module includes bias means urging said driven element toward said second position; and

snap acting means including a plunger engageable in said first detent to resist shifting of said driven element to said first position and engageable in said second detent to resist shifting of said driven element to said second position and biasing means urging said plunger into said detents with a predetermined force to provide a selected amount of resistance to shifting of said driven element.

6. A sequencing control module as set forth in claim 4 wherein:

said drive means includes biasing means urging said driven element toward said second position, a temperature responsive expansive rod normally resisting shifting of said driven element toward said second position and heat motor means disposed in heat exchange relationship with said rod.

Claims

1. A sequencing control module comprising: a housing; first and second controlled device sets spaced apart a selected distance on said housing, said first controlled device set including first and second contacts mounted from said housing, said second contact being mounted for movement into engagement with said first contact; a driven element carried from said housing and shiftable to a first position to actuate said first controlled device set and to a second position to actuate said second controlled device set; electrical drive means mounted on said housing, coupled with said driven element, and including first and second circuit means and further including a lever arm shiftable in one direction to shift said driven element to said one position and a switch control arm projecting therefrom and means coupling said switch control arm with said second contact; first and second position control elements mounted on said housing for selectively opening said first and second circuit means; control element actuating means coupled with said drive means and operative upon shifting of said driven element to said first position to engage said first control element to open said first circuit means and upon shifting of said driven element to said second position to engage said second control element and open said second circuit means; and control means for selectively completing said first and second circuit and including coupling means loosely coupling said driven element with said lever arm to provide a sufficient amount of play between said lever arm and element when said element is in said first position to enable said control element actuating means to engage said first control element to open said first circuit means while said driven element remains in said first position.

2. A sequencing control module as set forth in claim 1 wherein: said driven element is formed with fiRst and second spaced apart detents and said module includes bias means urging said driven element toward said second position; and snap acting means including a plunger engagable in said first detent to resist shifting of said driven element to said first position and engagable in said second detent to resist shifting of said driven element to said second position and biasing means urging said plunger into said detents with a predetermined force to provide a selected amount of resistance to shifting of said driven element.

3. A sequencing control module as set forth in claim 1 wherein: said drive means includes biasing means urging said driven element toward said second position, a temperature responsive expansive rod normally resisting shifting of said driven element toward said second position and heat motor means disposed in heat exchange relationship with said rod.

4. A sequencing control module comprising: a housing; first and second controlled device sets spaced apart a selected distance on said housing, said first control element including a switch body pivotally mounted from said housing and first and second electrically conductive blades projecting therefrom, said second blade being resilient and said moveable contact being mounted on said first blade, said second control element further including a first contact mounted from said first blade and a second contact mounted from said second blade and normally engaged with said first contact and bias means urging rotation of said body to normally maintain said stationary and moveable contacts in their closed positions; a driven element carried from said housing and shiftable to a first position to actuate said first controlled device set and to a second position to actuate said second controlled device set; electrical drive means mounted on said housing, coupled with said driven element, and including first and second circuit means; first and second position control elements mounted on said housing for selectively opening said first and second circuit means; and control element actuating means coupled with said drive means and operative upon shifting of said driven element to said first position to engage said first control element to open said first circuit means an upon shifting of said driven element to said second position to engage said second control element and open said second circuit means, and further including means carried by said driven means and engageable with said second blade and coupling means operable upon said drive means shifting said driven element to said first position to disengage said moveable contact from said stationary contact and upon shifting of said driven element to said second position to disengage said second contact from said first contact.

5. A sequencing control module as set forth in claim 4 wherein: said driven element is formed with first and second spaced apart detents and said module includes bias means urging said driven element toward said second position; and snap acting means including a plunger engageable in said first detent to resist shifting of said driven element to said first position and engageable in said second detent to resist shifting of said driven element to said second position and biasing means urging said plunger into said detents with a predetermined force to provide a selected amount of resistance to shifting of said driven element.

6. A sequencing control module as set forth in claim 4 wherein: said drive means includes biasing means urging said driven element toward said second position, a temperature responsive expansive rod normally resisting shifting of said driven element toward said second position and heat motor means disposed in heat exchange relationship with said rod.