Патент USA US2111431код для вставки
March 15, 1938. w. o. LUM 2,111,431 CONTROL MECHANISM Filed March 31, 1934 Inventor‘: 20 26 1/5 Wa Pier‘ 0. Lum b9 M7 8. 2M His Attorney. Patented Mar. 15, 1938 2,111,431 UNITED STATES PATENT OFFICE 2,111,431 oomor. MECHANISM Walter 0. Lum, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York “ Application March 31, 1934, Serial No. 718,395 8Claims. (Ul. 158-—42.1) My present invention relates to control mecha nisms, particularly safety circuit control switches and to furnace control systems embodying safety circuit control switches. One of the objects is 5 to provide an improved mechanism for trans mitting motion whereby a safety control switch may be operated from one ~control position to another in response either to a single reciproca tion of a given amplitude of a reciprocating mo .10 tion transmitting element or to a series of re ciprocationsof lesser amplitude of the element. Another object is to embody such a safety con trol switch mechanism in a furnace control sys tem. .15 In order that the principles underlying my in vention may be clearly understood I have de scribed and illustrated different embodiments thereof in a control switch mechanism and also described and illustrated the manner in which 20 such switch mechanism may be embodied in a furnace control system. In the operation of oil burner equipment there is danger of conditions arising such that abnor mal pressures, sometimes of an explosive nature, 25 will develop in the combustion chamber. It has been the practice to provide safety doors or like vent means to relieve these abnormal pressures. Since such abnormal pressures are due to im proper functioning of the burner mechanism, it so is desirable to deenergize the fuel supplying ap paratus and control therefor immediately upon the occurrence of the abnormal pressure, and mechanism for effecting such deenergization of the oil burner equipment in response to abnormal 35 pressures forms the subject matter of my co normal pressure will cause the pressure release door to vibrate to an extent su?lcient only to allow the escape of puffs of undesirable fumes without being sufficient to completely operate the safety switch to open-circuit position. In other words, the amplitudes of the successive outward movements of the door, which is biased to return to closed position, will not be sumcient to move the elements of the safety switch a sufficient dis tance with respect to each other to disengage 10 them. It is desirable, however, to deenergize the oil burner equipment upon the occurrence of such relatively small pulsating abnormal pres- . sures as well as upon the occurrence of abnormal pressures of explosive proportions, since both 15 denote improper operation of the burner equip ment. A further and more speci?c object of my invention is, therefore, the provision of im proved, simple and reliable control mechanism for insuring deenergization of an oil burner 20 equipment upon either a single opening of the oil burner pressure relief door to a predetermined degree or a series of openings of the door to lesser degrees. ' Fig. 1 is a schematic showing of an oil burner furnace, partially cut away, to which my inven tion is applied; Fig. 2 is a detailed perspective showing of the elements of one embodiment of my invention; and Figs. 3, 4, and 5 illustrate successive steps in the operation of the mecha nism shown in Fig. 2. Figs. 6, 7, and 8 illustrate another embodiment of my invention and suc cessive steps in the operation thereof, and Fig. 9 illustrates schematically the manner of applying this last embodiment to an oil burner furnace 35 pending application, Serial No. 596,067, filed similar to that shown in Fig. 1. Referring to the drawing, an oil burner fur March 1, 1932 and assigned to the assignee of the present invention. In the apparatus therein nace I0 having a combustion chamber ii, is equipped with a motor operated pump and com described, a safety switch, connected to an ex 40 plosion relief door by means of a chain or like pressor unit I2 for supplying fuel and air to an atomizing nozzle 13. The combustion mixture connection, is automatically operated to stop op discharged from the nozzle into the combustion eration of the fuel supplying apparatus and con chamber is ignited by means of electrodes 14 and trol therefor in response to actuation of the re the products of combustion pass from thence lief door by pu?back or other abnormal pres 45 sure conditions within the combustion chamber. through the stack breaching l5 into the smoke There also may occur in the operation of oil pipe it which leads to the stack. A pressure re burner equipment, improper operating conditions lief port I1 is incorporated in the top of the which will not be of such nature as to cause ab stack breeching, and a pressure relief door 20, pivotally mounted on the breeching as shown at 2 I, is biased by means of spring 22 to close the re 50 normal pressure of explosive proportions but 50 which will cause irregularly recurring pulsations of abnormal pressure of relatively small mag nitude. It has been found in the operation of an oil burner apparatus equipped with safety mech anism‘such as described in my above referred to 55 application, that such small mutations of ab lief port. Electrical energy for the operation of the burner mechanism and the electrodes is supplied from lines 23, 24 through a safety switch which is shown at 25 as consisting of a terminal box 2 0,111,4a1 26 secured to the stack breeching by means of mounting plate 21 and provided with a socket II to which the electrical leads from lines a, 24 are brought by means of conduit 2!. A movable switch element in the form of a plug 80 having contacts II, II. is provided for bridging the ter minals in the socket 20. In accordance with my present invention, a one-way force transmitting mechanism is pro '10 vided for connecting the door 20 with the contact carrying plug it and for e?'ecting disengaging movement of the plug either in a single step in response to opening of the door to a predeter mined distance or in a series of steps in response 16 to a series of openings of the door to lesser dis tances. The principal element of this mechanism is a link member, in the form of a hook-shaped ' segment II. pivotally mounted at 83 upon clamp I4 secured to the free end of the door It. The segment engages a slotted stirrup I. attached to the plug Ill and is arranged to depend from the pivotal mounting with its free end extending through the slot and its inner face 31 in frictional engagement with the underneath side of the 25 closed end of the slot in the stirrup. This inner face 31 of the segment is in the form of an irre versible cam surface. successive points of which as illustrated by points a and b, are at progres sively shorter distances from the pivot point If, 80 and therefore from the free end of the door 20. It is preferred that the cam surface be continuous for reasons hereinafter to be set forth. A weight ll is amxed to the hook-shaped segment at some point horizontally o?set from the vertical line of motion of the pivot point It so that it will provide a relatively large gravitational force acting about the lever arm, consisting of the portion of the segment between the weight and the pivot point, to tend to swing the segment in a counterclock 40 wise direction as viewed in Figs. 2 to 5 inclusive. 45 50 55 60 In the operation of the oil burner equipment conditions may arise in the combustion chamber which will produce abnormal pressures of sum cient magnitude to blow open the door 20. When the door is blown open by a pu?'back, explosion or similar large abnormal pressure the movement thereof will be su?icient to disengage the con tacts II and II of the plug 30 from the terminals in the socket 28 in a single stroke to deenergize the oil burner and ignition equipment. It will be apparent that upon upward movement of the door 20 the frictional engagement of the inner surface of the hook-shaped segment 35 with the end of the stirrup 36 will ‘become a positive engagement to provide a positive operating connection be tween the door and the movable plug so that outward movement of the door will pull the plug upward a distance proportional to the amplitude of the movement of the door, and a single open ing of the door to a predetermined degree will be su?lcient to completely disengage the contacts of the safety switch 25. There might also arise in the operation of the oil burner conditions such that pulsating pres 65 sures of small magnitude may occur within the combustion chamber, and these pulsations will be sumcient to impart to the pressure relief door only a vibratory opening movement such that each upward movement of the door will be of insu?i 70 cient amplitude to completely disengage the con tacts of the safety switch 25. Such conditions are, of course, undesirable since they denote im proper operation of the oil burner equipment and will also allow continued escape of combustion 75 gases from the pressure relief port into the space surrounding the oil burner furnace. Hence it is desirable to have the oil burner equipment de energized after repetition of this pulsating con dition for a certain length of time. Figs. 8, 4, and 5 illustrate in two steps the operation of the safety switch in response to vibration of‘ the pressure release door 20, but it is to be understood that this is merely illustrative and that it may take a much larger number of successive steps to completely ‘disengage the contacts of the safety switch. When the door 20 is at rest in closed position and the plug II is completely seated in the socket 28 which is the normal condition for proper operation of the furnace, a point on the‘ cam surface 31 having a connection distance de noted a will engage the stirrup 38. Upon a slight upward movement of the door Ill due to a pulse’ tion of abnormal pressure the plug III will be caused to follow the movement of the door II in proportion to the extent of opening thereof. This 20 will effect a partial disengagement of the plug contacts from the terminals of the box It as shown in Fig. 4. Now upon return of the door to its closed position, were it not for the weight II the segment would tend to retain its original position as shown in the dotted lines of Fig. 4, and would tend to push the plug back into the socket in the terminal box 20. However, the bias ing effect of the weight ll tends to cause the segment to rotate in a counterclockwise direction. 80 thus forcing a succeeding bearing point of the cam surface into engagement with the stirrup I‘, such successive bearing point having a connec tion distance such as b which is shorter than that of the connection distance a of the bearing point which ?rst engaged the stirrup ll. . This will produce a shorter connection distance be tween the door and the plug 30 so that succeed~ ing upward movements of the door will produce added increments of upward movement of the 40 plug and will eventually e?'ect complete disen gagement of the contacts 8| and 32 from the terminals oftheterminalbox It asillustratedin Fig. 5. It will thus be seen that my improved linkage mechanism provides means for imparting 45 progressive increments of movement to the mov able switch element or plug 30 upon successive vibration of the pressure relief door 20, and that a predetermined summation of the outward movements of the door will effect complete dis 50 engagement of the safety switch to deenergize the electrical circuit of the oil burner and ignition equipment. It is also apparent that the continu ity of the cam surface provides for in?nitely small changes in connection length so that the mecha 55 nism,will function regardless of the amplitude of movement of the door. Figs. 6 to 9 inclusive illustrate a modi?ed form of my invention wherein the linkage mechanism is particularly adapted for use with a‘pressure relief door having substantially horizontal move ment. The operating link in this embodiment is in the form of a closed segment 4| having an in ner bearing face ll similar to the irreversible cam surface I‘! of the link ll in the embodiment ?rst M described. A weight 42 of arcuate shape similar to that of a portion of the segment is riveted or otherwise fastened to the segment as shown at II and 4 . Terminal box 20 is incorporated in the wall of 70 the furnace l0, and the socket therein is ?ush with the wall. Plug 30 is provided with one or more projecting ears 45 for engagement with the inner surface of the segment. The segment is 'pivotally secured by means of pin 40 upon the , 3 9,111,481 end of rod 41 which passes through an opening 48 in the adjacent side of the stack breeching and through the interior thereof to the opposite side where it is fastened to the pressure relief door 50 which is arranged to close the port ‘I in the wall of the breeching. Guide means 52 are provided to steady the rod and aid in hold ing it and the door in position, and spring means 53 are provided to bias the door in closed position. The operation of the mechanism of the em 10 bodiment last described is similar to that de scribed in connection with Figs. 2 to 5 inclusive. Under normal conditions in the furnace, the pro :Iection 45 will be engaged by a bearing point on the cam surface which has a connection distance a. Outward movement of the door 50 will cause the rod 41 to slide in the guides 48 and 52. This will cause segment 40 to pull on the plug 30 and eifect partial disengagement of the contacts 3| 20 and 32 to an extent proportional to the distance of opening of the door, as for instance, to a posi tion such as shown in Fig. 7. Subsequent return of the door to closed position releases the fric tional force between the bearing surface 4i of 25 the segment and the projection 45, and allows the segment to swing in a counter-clockwise di rection under the in?uence of weight 42 until a succeeding bearing point having a shorter dis— tance, such as b, is forced into engagement with the projection. Thus, successive outward vibra tions of the door impart progressive increments of movement to the movable switch member or plug and will completely disengage the contacts of the plug from the terminals in the terminal box, as shown in Fig. 8, after a predetermined sum mation of said increments of movement. when the plug is completely disengaged it will hang suspended from the segment by means of the pro jecting ear 45 which will rrst upon the lower por 40 tion of the segment 40, and the plug must be manually reset to reestablish the energizing cir to closed position and arranged to open different distances in response to abnormal pressures of different magnitudes within the combustion chamber, and means for effecting either continu ous movement of the switch means from one of said circuit controlling positions to the other in response to a single opening of the door to a pre determined distance or step by step movement of the switch means from said one circuit con trolling position to the other in response to a series of lesser openings of the door. 2. The combination with a furnace having a combustion chamber, electrically operated fuel burner means therefor and an energizing circuit for said electrically operated means, of electrical 15 switch means movable between two circuit con trolling positions to control the energization of said circuit, a pressure relief door normally biased to closed position and arranged to have different degrees of opening in response to abnormal pres 20 sures of different magnitudes within the com bustion chamber, and means interconnecting the door and the switch means including a one-way force transmitting mechanism for effecting movement of the switch means from one of said 25 circuit controlling positions to the other in re sponse either to a single opening of the door to a predetermined degree or to a predetermined sum mation of openings of the door to lesser degrees. 3. The combination with a furnace having a 30 combustion chamber, electrically operated fuel burner means therefor and an energizing circuit for said electrically operated means, of switch means movable between two circuit controlling positions to control the energization of said cir 35 cuit, movable pressure responsive means opera tively associated with the furnace to vibrate in response to pulsating abnormal pressures within the furnace combustion chamber, and means in terconnecting the pressure responsive means and 40 the switch means for effecting progressive move cuit of the oil burner. It will be evident that the . ment of the switch means from one of said cir link may be made in the form of two segments, cuit controlling positions to the other in re having similar contours, ?xedly secured to each sponse to repeated vibration of the pressure re other in spaced apart side by side relation and sponsive means due to repeated pulsations of ab pivotally mounted on opposite ends of the pivot normal pressure in the combustion chamber. 4. The combination with a furnace having a pin 46, and the bearing surfaces of these two combustion chamber, electrically operated fuel segments may be arranged to engage projecting burner means therefor and an energizing circuit ears 45 on opposite sides of the plug 30. From the foregoing description it will be seen for said electrically operated means, of switch 50 means operable to control the energization of said that by my invention I have provided a mecha circuit and means for insuring deenergization of nism for greatly increasing the safety and relia said circuit upon the occurrence of pulsating ab bility of operation of an oil burner furnace. The embodiments of the invention herein illustrated normal pressures in the combustion chamber in cluding a pressure relief door operatively asso .» and described have been selected for the purpose of setting forth the principles involved. It will ciated with the furnace and vibratorily movable in response to said pulsating abnormal pres be apparent, however. that the invention is sus sures, biasing means for holding the door nor ceptible of being modi?ed to meet different con ditions of use and that its use is not limited to a mally in closed position, and means intercom necting the door and the switch means including 60 switching mechanism for an oil furnace safety switch but maybe employed with equal advan tage in any situation where a control mechanism having similar characteristics is desired. Such modifications are believed to be within the spirit 65 and scope of my invention and are intended to be covered by the appended claims. What I claim as new and desire to secure by Letters Patent of the United States, is: 1. The combination with a furnace having a 70 combustion chamber, electrically operated fuel burnermeans therefor and an energizing circuit for said electrically operated means, of electrical switch means movable between two circuit con trolling positions to control the energization of 75 said circuit, a pressure relief door normally biased 45 50 55 60 a one-way force transmitting mechanism for im parting progressive increments of movement to said switch means toward open circuit position in response to a series of successive vibrations of the door due to said pulsating abnormal pres 65 sures. 5. In combination, electric circuit controlling means having a switch element movable between two circuit controlling positions, and means for transmitting motion to said element including a movable element and a one-way force trans mitting mechanism interconnecting said switch element and movable element for effecting move ment of the switch element from one to the other of said circuit controlling positions in re 75 4 2,111,4s1 spouse to either a single movement of said mov-_ able element through a predetermined distance or the repeated movement 0! the movable ele ment through a lesser distance. 6. In combination, circuit controlling means having a switch element movable between two circuit controlling positions, and means for trans mitting motion to said element including a re ciprocating element, and a one-way iorce trans 10 mitting mechanism mechanically interconnect ing said switch element and said reciprocating element for moving said switch element from one to the other oi’ said circuit controlling positions in response to either a single reciprocation oi the reciprocating element through a predetermined distance or a series of reciprocations of said reciprocating element through a lesser distance. 7. In combination, circuit controlling means having a switch element movable between two 20 circuit controlling positions, and mechanism for transmitting motion to said element including ‘a pair oi’ members having a one way interlocking engagement for movement thereof as a unit with said switch and biased to have relative movement therebetween in the opposite way to provide a movable connection of varying lengths with the switch element. 8. In combination, circuit controlling means having a switch elementmovable between two circuit controlling positions, and mechanism for transmitting motion to said element including a 10 pair oi’ relatively movable members, one being pivotally mounted and having a one way inter locking engagement with the other member and biased to successively shorten the distance be tween the mounting point of said one member and the other member upon reciprocation done 01’ said members to eiiect progressive increments of movement of the switch element between said positions. WALTER 0. LOB.