Патент USA US2405014код для вставки
`July 30, 1946. M. J. CAPARONE 2,405,014 SNAP ’ACTION MECHANISM ' Filed May :5, 1944 ¿e m 66 62 my /// /t’ 64j “@ÉÃ". JT' .5. ‘ma BY m ,. L.Wmy_/ECmmm vr. Patented July 30, 1.946 2,405,014 UNITED STATES PATENT OFFICE 2,405,014 SNAP ACTION MECHANISM Michael J. Caparone, Pasadena, Calif., assignor to Grayson Heat Control, Ltd., Lynwood, Calif., a, corporation of California Application May 3, 1944, Serial No. 533,976 5 Claims. (Cl. 74-100) 1 2 This invention relates to snap-acting mecha nisms and, more particularly, to overcenter spring jections I6 formed on a channel-shaped base member I8 which is positioned within the frame I0 and extends substantially parallel with the side wall I4. Preferably, the base member I 8 is and lever 'devices for operating valves or switches. A common form of overcenter snap mechanism embodies a frame` having main and secondary 5 supported for rocking movement relative to the levers fulcrumed therein and connected by a frame I4 andy for this purpose, the projections spring in such manner that gradual movement of I I3 thereof are provided with. notched portions the main lever carries the spring from side to 20 which bear upon knife-edged portions 22 side of the fulcrum of the secondary lever to pro formed on the adjacent edges of the slots I2. duce a snap action therein. The torque required 10 The base member I8 may be adjusted on its bear merely to overcome friction and inertia of the ings by means of a set screw 24 which projects secondary lever at the beginning of the snap ac through the side wall I4 of the frame and is mov tion is insufficient to permit this lever to exert able into engagement with the base IB at a point any appreciable force. It is only after the snap remote from the projections I6. action has progressed sufficiently to increase the 15 A main lever 26 of considerably less width than torque that the secondary lever can perform use the width of the frame ID is mounted centrallir ful work. The necessity for such travel on the thereof and extends from the base I8 to the op part of the secondary lever to increase the torque posite side wall 28 of the frame I9. A knife magnitude reduces the force of the snap action edged portion 30 formed on one end of the main and limits the power and. usefulness of such de 20 lever .26 cooperates with a V-shaped notch or vices for various applications, » bearing 32 formed in the side wall 28 approxi An object of this invention is to cause the snap mately midway between the ends thereof- The mechanism to exert its maximum force at the opposite end of the main lever 26 is bent at sub instant that snap movement occurs. stantially a right angle to the lever body and Another object of the invention is to utilize projects between the side walls of the base I8 substantially the full stroke of the secondary forming a free end movable in an arcuate path. lever to perform useful work. This end has a countersunk opening 34 formed Another object of the invention is to retain therein and the adjacent edge is suitably notched the simplicity of existing snap mechanisms while to provide a suspension point 36 for one end of improving the action thereof. 30 a tension spring 38 which is hooked therearound. Another object of the invention is to render the The opposite end of the spring 38 is hooked magnitude of the force exerted by the snap lever around a similar suspension point 40 formed by either variable or fixed, as desired. a countersunk aperture intermediate the ends of Other objects and advantages will become ap a secondary lever 42. The secondary lever 42 is parent from the following description taken in forked between the suspension point 40 and the connection with the accompanying drawing, lower end thereof to provide clearance for the wherein spring 38. The forked ends of the secondary Fig. 1 is a front elevation of the improved lever 42 are provided with knife edges 44 for co snap-acting mechanism; operation with V-shaped notches or bearings 46 Fig. 2 is a section taken on the line 2_2 of 40 formed in the side walls of the base member I8 Fig.1; approximately midway between the projections Fig. 3 is a section similar to Fig. 2 but show IB and the opposite ends. The spring member 38 is normally under tension and serves to force ing the mechanism in another operating position; Fig. 4 is a section similar to Fig. 2 but show ing the snap mechanism in still another operat ing position; the main lever 26 upwardly against its bearing Preferably, the bearings 32 and 46 for the main and secondary levers are in axial alignment and, in the normal or unoperated position of the snap mechanism shown in Fig. 2, the spring 38 45 32. Fig. 5 is a section taken on the line 5-5 of Fig~ 1. Referring more particularly to the drawing, is located on the right-hand side of the center the conventional parts of a snap-acting mecha 50 line of these bearings as viewed in 2. nism are shown as comprising a channel-shaped The free end of the secondary lever 42 opposite frame I0 having a pair of spaced slots I2 ex the knife-edge 44 is bent substantially perpen tending through the bottom wall thereof adja dicular to the lever body and extends in the op cent the one side wall I4 thereof. The slots I2 are each adapted to receive one of a pair of pro- Y posite direction from the free end of the main lever 26 to form an operating portion 48. The 2,405,014c operating portion 48 is provided with an aperture 50 through which the knife-edged portion 30 of the main lever freely projects. The operating portion 48 is adapted for operative engagement in accordance with the movement of the control device as represented by the push rod 58. To this end, means are provided to apply a restraining force to the secondary lever 42 to prevent any movement thereof until sufficient spring tension has been established to overcome the force -exerted by the means. Under such con with the device to be operated, such as a switch or the valve 56 shown in broken linesl in the drawing, As indicated in Fig. 4 the valve 56 is moved off its "seat in response to operation of the snap mechanism and may be returned by action of a spring (not shown). __ v ditions, it will be apparent that the mechanism lo vcannot attain a condition of substantial equilib The secondary lever 42 is further provided with an elongated aperture 52 overlying and connected to aperture 4l and in axial alignment with an aperture 54 formed in the frame I0. The aper tures 52 and 54 are adapted to providefreev ac cess to the main lever 26 from the exterior of the frame IIJ in order thatV gradual'movement may be imparted thereto by suitable means. Such movement may result from pressure applied to the main lever 25 by a control device for the >valve or switch to be operated and the broken lines in the drawing are intended to represent the actuating portion‘or push rod 58 cfa thermostat or other control device suitable for this purpose. In the operation of the mechanism so far de scribed, the parts are moved from the normal or unoperated position shown in Fig. 2 to thefully «operated position shown in Fig. 4 by pressure applied to the main lever 26 by the push rod 58. The valve 56 to be operated is shown in Fig. 2 as being in closed position and the operating end 48 of the secondary lever is shown as slightly spacedtherefrom. 4 valve 56 or for operating a switch or other device Movement of the push rod 58 to the left as viewed in Fig. 2 will cause grad ual movement of the main lever 26 to the left as ; it pivots in its bearing 32 and the suspension point 36 of the spring 38 will move correspond ingly in an arcuate path until it is 'in substantial alignment with the knife-edge 44 of the second ary lever 42. The centerline of this position is designated by the broken line A-A in Fig. 2, it being noted that the secondary lever 42 would not partake of the gradual movement due to the component of force acting to produce a clockwise -~rium and the dead center position is eliminated. >,In-this embodiment, the means so provided may take the form of a permanent magnet 60 com prising a pair of pole faces 62 connected by a bar portion 64. The magnet 60 is mounted on the frame I0 in any suitable location to exert mag netic force -upon the secondary lever 42 and is shown herein as being intermediate the push rod '58 and the side wall 28 of the frame. It will be apparent, however, that such location of the mag net 60 may be varied to change the operating force exerted by the secondary lever 42 and that magnets of different size and magnetism may be substituted for the same purpose. The pole faces 62 may project through aper tures 66 formed in the frame I0 at the desired location and a retaining clip 68 of sheet material may extend around the bar portion 64 and through slots provided therefor in the frame I0 and be swaged into close engagement with the frame l0 on the inner wall thereof to secure the magnet in position. In the operation of the improved snap-action mechanism described, the suspension point 36 must travel overcenter across the line A--A with out any movement being imparted to the sec ondary lever 42 due to the magnetic force of the magnet 6i) acting thereon. The main lever » 26 continues to move to the left, as shown in Fig. 3 of the drawing, until suflicient spring tension has been established by such movement relative to the secondary lever 42 to overcome the restrain ing force of the magnet 60. It is apparent that the total force that can be exerted by the sec ondary >lever 42 at the instant that snap action When suspension point 35 «fr rotation of lever 42. is aligned with knife-edge 44 the mechanism has --occurs is equal to the magnetic force acting on the secondary lever 42. 'In this invention move reached> a dead center position thus placing the ment of the parts to dead center is prevented and parts in substantial equilibrium. Continued pres the snap mechanism is enabled to exert its maxi eure applied by the push rod 58 to the main le ver 26 will cause the suspension point 36 to travel 50 mum force at the instant that snap action occurs. As a small gap is provided between the end of overcenter to the left across the line A-A. The '- the valve 56 and the operating end 4S of the component of force then tends to produce a coun secondary lever 42 prior to snap action, the sud ter-clockwise rotation of the secondary lever 42 whereupon the tension spring 38 will snap the ' den release of force as described creates a high impact force which is usually sufficient to force operating end 48 of the secondary lever from the dead center position to the fully operated posi Such snap action causes -tion shown in Fig. 4. the valve 56 to be moved off its seat and to re main in such position until the push rod 58 re turns to its former position and permits the mech anism to resume the normal position shown in Fig.‘2. From the foregoing description of the opera tion of a conventional snap-acting mechanism, it will be apparent that the operating end 48 of the secondary lever 42 cannot exert sufñcient force to overcome the closing spring of valve 55 until the lever has travelled far enough to in crease its torque to such magnitude as will serve the purpose. Hence, only a portion of the travel can be utilized to perform useful work. This invention is more particularly directed to in creasing the range of snap-action movement of the operating lever 42 in order that maximum force may be delivered thereby for unseating the the valve off its seat even if it is corroded or stuck thereto. Such impact would of course be equally useful in freeing switch contacts which may have >become similarly corroded or stuck in closed position. Moreover, due to the increased force of the snap action provided by this inven ' tion the valve 55 could be moved to its seat under ` the action of a more powerful spring than it is possible to provide for use with snap mechanisms of limited snap movement. It will be understood that various changes may be made in the arrangement and combina tion of parts and in the details of construction herein disclosed within the scope of the appended claims without departing from the spirit of the invention. I claim: l. Snap-acting mechanism oi the character de scribed comprising in combination, a pair of levers pivotally mounted at opposite ends, a tension 2,405,014 spring connecting the free ends of said levers and adapted to establish snap-action thereof in re sponse to overcenter movement relative to said mounting, and means adapted to apply a force for preventing one of said levers from partici 6 one end thereof, a tension spring connecting the free ends of said levers and being located on one side of the centerline of said bearings, said main lever being adapted upon pivotal movement thereof to travel overcenter and impart snap action to said secondary lever, and means adapted pating in said movement until sufficient spring tension has been established to overcome said to exert magnetic force on said secondary lever force. to prevent pivotal movement thereof until said 2. Snap-acting mechanism of the character de main lever has travelled overcenter and estab scribed comprising in combination, a pair of levers 10 lished suilicient spring tension to overcome said pivotally mounted at opposite ends, a tension force. spring connecting the free ends of said levers 5. Snap-acting mechanism of the character de and adapted to establish snap-action thereof in scribed comprising in combination, a frame hav response to overcenter movement relative to said ing spaced bearings therein, a main lever having mounting, and magnetic means for preventing one end pivotally mounted in one of said bearings one of said levers from participating in said and a free end extending adjacent another said movement until suilîcient spring tension has been bearing, a secondary lever having one end piv established to overcome the force exerted by said otally mounted in said other bearing and a free means. end extending adjacent the first one said bear 3. Snap-acting mechanism of the character de 20 ing, a tension spring connecting said free ends scribed comprising in combination, a pair of levers and being located on one side of the centerline pivotally mounted at opposite ends in bearings, a of said bearings, said levers and spring being so tension spring connecting the free ends of said arranged that gradual movement of said main levers on one side of the centerline of said bear lever in one direction on its pivotal mounting will ings, one said connected end being movable over 25 cause the free end thereof to travel overcenter center to establish snap-action in the other, and and impart snap-action to said secondary lever, means adapted to apply a force on the lever hav and a permanent magnet carried by said frame ing said other connected end for preventing par and adapted to exert its magnetic force on said ticipation thereof in said movement until sunl secondary lever during a portion of said main cient spring tension has been established to over 30 lever travel to restrain said secondary lever from come said force. pivotal movement until sufilcient spring tension 4. Snap-acting mechanism of the character de has been established by said main lever travel to scribed comprising in combination, a main lever, overcome said force. a. secondary lever, oppositely disposed bearings for pivoting said main and secondary levers at 35 MICHAEL J. CAPARONE.