Патент USA US2122700код для вставки
July 5, 1938. C. A. SCHAEFER 2,122,700 ELECTRIC SWITCH Filed Nov. 2, 1936 nk H I @ .E. 4: 4& 48 E [3,4 ‘s5 BY INVENTOR. Carl ?f 5c%aefrn ATTORNEY. ‘' 2,122,700 Patented July 5, 1938 PATENT OFFICE UNITED STATES 2,122,700 ELECTRIC SWITCH 'Carl A. Schaefer, Detroit, Mich, assignor to Square D Company, Detroit, Micln, a corpora tion of Michigan Application November 2, 1936, Serial No. 108,764 g (0]. 200-83) ' 5 Claims. This invention relates to electric switches auto matically operable‘ in response to an external condition. is rigidly mounted on the arm 1 and is adapted ' . One object of the present invention is to pro 5 vide an improved form of electric switch operat ing with a snap action in response to external pressure variations. Another object of the invention is to provide an improved form of high pressure cutout switch 10 used in conjunction with a normal pressure re sponsive switch but having individual contacts. Other objects and features of the invention will be readily apparent to those skilled in the art from the following speci?cation and appended 15 drawing illustrating certain preferred embodi ments of the invention in which: Figure l is a front elevational'view of a switch assembly according to the present invention with the front cover removed and parts broken away 20 to show internal parts. . Figure 2 is a horizontal sectional view on the line II—1I of Figure 1. Figure 3 is a diagrammatic view showing the control system.v ing arm 8 toward engaged position. For moving the contacts to the disengaged position a pin it _ The normal pressure responsive mechanism shown in Figure 1 is more fully described and claimed in applicant's co-pending application, Serial No. 77,723, ?led May 4, 1936 for Electric switches. This switch embodies an insulating 30 enclosure l for the switching mechanism ‘and an operating means comprising a normal pressure re sponsive assembly generally indicated at 4 and the switch is provided with a further protective device comprising a high pressure responsive cut 35 out indicated generally at 5. Within the enclo sure I is mounted a conducting bracket 6 having a pair of arms 1 and 8 pivotally mounted thereon to be engaged by an insulating portion l1 on a lever I 8 pivoted to a ?xed part. A compression spring 19 biases the lever 18 downwardly and is provided‘ with an adjusting screw 2! for adjust ing the range of operation of the device. The normal pressure responsive unit comprises a chamber 22 having a bellows 23 therein. A pin 24 is connected to the bellows and is adapted to press against the under side of the lever 18. A spring 25 is adapted to be adjusted by a knurled nut 26 which may be provided for varying the 15 limits of the range variation of the device. The high pressure cutout unit according to the present invention comprises a separate and dis tinct switching mechanism actuated upon the attainment of a predetermined maximum pres sure to open its contacts. This switch comprises an enclosure 21 having connected to the bottom thereof a bellows chamber 28 within which is dis posed an expansible bellows 29 having connected thereto a pin 3| for actuating the switching mem ber. About the pin 3| is disposed a compression spring 32 opposing movement of the pin and adjustable by means of a threaded cylinder 33 through which the pin 3| projects. Within the chamber 21 is disposed an insulating block 30 ‘on which are disposed spaced contacts electrically connected to the terminals 34 and 35. The base 30 is supported on a metallic bracket 36 and within this bracket is hingedly mounted a link 31 having arms 38 at either side of its opposite end and a centrally disposed bearing point 39. An adjusting member 4| is threaded into the en closure 21 and is provided with a similar bearing by means of the trunnion ends of studs l0 thread- ' point 42. ed into the upstanding walls of. the bracket. 40 These arms thus rotate about the same pivotal axis and are disposed as shown in generally par allel relation and connected together with a lost motion connection by the headed movable con tact surface described hereinafter. The arm 8 is 45 a conducting arm carrying a contact surface 9 thereon at the forward side of the magnetic arm 1, which contact surface is headed or other wise restricted in its movement with respect to the arm 1. A stationary magnet II is provided 50 for attracting the arm 1. A stationary contact 12 is mounted on a resilient arm 13 and a cam 14 is provided for adjusting the position of the sta tionary contact 12 and hence the vair gap between the magnetic arm 1 and the permanent magnet I 55 II. A light tension spring 15 biases the conduct-' In 0 A compression spring 43 is provided with bearing seats 44 at its ends which receive the bearing points 39 and 42. The link 31 and 40 the spring 43 thus comprise an over center toggle adjustable through the member 4|. A pair of tension springs 45 bias the arms 38 to’ a fixed part of the enclosure. Upon the link 31 as by means of the knife-edged pivots 40 is mounted a contact member 46 including an insulating por-_ tion 41 carrying a contact plate adapted to bridge the stationary contacts on the base 33. A pair of light tension springs 48 are mounted at the contact side of the knife-edged mounting of the 1' contact arm 46 and have their opposite ends con nected to ?xed points on the enclosure. An adjustable stop 49 is positioned to engage the contact arm 46 at the side opposite the contact carrying portion thereto. 65 2 2,122,700 A stationary stop 5| is provided for limiting the downward movement of the link 31. lThe pin Ii is provided with a pointed end received within a cooperating groove in the link 51. 10 The operation of the normally responsive pres sure switch is as follows: The parts as shown in Figure 1 are in the closed circuit position. Upon a decrease in. pressure within the bellows chamber 22 the lever I! will move downwardly under the bias of the spring I. whereupon the insulating portion i1 will en gage with the pin IS on the lever ‘l and rotate this arm in a clockwise direction until it engages with the conducting arm 5 whereupon the arms ‘I and I move together and move the contact surface 5 which is rigid with the arm 5 into its disengaged position. Similarly, when the pres sure within the bellows chamber 22 increases while the contacts are maintained in the oil 20 position the lever l8 will be moved upwardly, thus permitting the contacts to be moved into engaged position under the bias of the spring i5. Due to the rapidly increasing force of the magnet II as the contacts move toward engagement the 25 meeting of the contact surfaces will concur with a snap action under the in?uence of the perma nent magnet ll. Movement of the cam surface l4 will move the stationary contact relative to the magnet and by varying the air gap will vary 30 the differential of pressure to which the switch I: operates. . The compression spring I! is adjusta ble to vary the range of operation of the device. The spring 25 is adjustable to raise or lower the limits of the range of operation of the device. The operation of the high pressure cutout mechanism is as follows: The parts as shown in Figure 1 are in the closed circuit position. Upon the attainment of a pre determined maximum condition within the bel 40 lows chamber 25 the pin 3| will be moved up wardly and by its engagement with the link 31 will move this link and contact arm 36 in an up ward direction. When the ‘toggle formed by the spring 43 and the link 31 approaches its dead 45 center position the force necessary to move it will 50 rapidly decrease so that the movement thereof will occur quickly. At this time the contact lever 45 will engage the stop 45 and cause rotation of the contact lever about its knife-edge support to move the bridging contact plate to disengaged position. Upon decrease in pressure within the bellows chamber 25 the parts will automatically reverse themselves and move to bridging engage ment with the stationary contacts. In the'open 55 ing operation, it is to be noted that contact pres sure is maintained until the contact lever sharp ly engages the adjustable stop 49 whereupon the lever is rapidly rotated about its knife-edge 60 mounting. The springs 45 are not ‘absolutely essential to the operation of the device but with out them the contact opening action is apt to be rather sluggish since at the instant of operation the force necessary to move the link 31 and the ~ contact lever upwardly is increased by the in sure at which the contacts will be open and that at ‘which they will be closed. Figure 3 illustrates diagrammatically a system employing the pressure switch assembly which has previously been described. This comprises a motor 52 vwhich may constitute a refrigerator compressor motor, or any other electrical trans lating device adapted to be connected to a line through a contactor 55 having a magnet coil 54 for effecting closing of the contact. In addition to the normal pressure switch 55 and the high pressure cutout 55 a manual three point switch 5'! having terminals 58 and 59 and a movable switching arm 5| is provided. With the switching arm placed in a neutral position as shown in 15 Figure 3 the control circuit through the coil 54 will be manually opened and the translating de vice will remain disconnected frciua the line. Upon movement of the switching arm 6| into en gagement with the terminal 59 the control cir cuit through the coil 54 will be closed with both the normal pressure switch 55 and the high pres sure cutout 58 in series with the coil. This is the normal automatic operating connection for the circuit as it is seen that with this connection if the pressures within the bellows chambers 28 and 22 are at certain values both the controlling contacts will be closed and the circuit will be com pleted through the coil 54 thus connecting the motor to the line through the contactor 53. Upon 30 a suitable decrease in pressure in the normal pressure switch 55 its contacts will be opened, thus opening the control circuit, whereupon the contactor 53 will open and disconnect the motor from the line. This is the normal automatic op~ eration of the device wherein the motor is con~ nected to and disconnected from the line in re sponse to variations in p1. assure within the bel lows 22. Upon the attainment of a predetermined maximum pressure within the bellows 28 the high pressure cutout 55 will operate to open its con tacts, thus opening the control circuit to discon nect the motor, regardless of the condition of the normal pressure switch and these contacts will remain open until the pressure within the bellows . chamber 25 decreases. In many instances it is desired to connect the motor or other translating device to the line for continuous operation inde pendent of the normal pressure switch but main taining the protection ail’orded by the high pres sure cutout. This is accomplished by moving the 50 switching arm 5| into engagement with the ter minal 55 whereupon the coil 54 will be connected in the control circuit in series with the high pres sure cutout 55 only and the switch 55 will be , shunted from the control circuit. With this connection the motor will be operated continu ously until the attainment of the predetermined maximum pressure within the high pressure cut out bellows 28 or until the manual switch is oper ated. While certain preferred embodiments of the invention have been speci?cally disclosed, it is understood that the invention is not limited creased tension in the springs 48. With the springs 45 the increased force of springs 48 forms thereto as many variations will be readily appar— ent to those skilled in the art and the invention only a very small part of the force to be overcome is to be given its broadest possible interpretation, so that they will not slow up the action of the’ within the terms of the following claims. toggle in effecting quick break of the contacts. Adjustment of the cylinder 33 will adjust the ‘pressure to which the device will operate to open the contacts. Adjustment; of the member 4i .will adjust the tension on the toggle link spring 43 75 and will adjust the differential between the pres l0 What is claimed is: ' 1. A pressure switch- comprising an element movable in one direction in response to a pres sure condition, adjustable spring means for op posing such movement, a pivoted member mov~ able in response to movement of said element. means biasing said member in a direction to op 3 ‘2,122,700 pose movement thereof by said element, a con tact arm pivoted on said member, means biasing said arm to contacts engaged position, over-cen ter spring means connected to said member and causing its movement to be snap-like in action, and a stop engaging said arm when said member is moved by said element to cause rotation of the ‘ arm against its biasing means to a contacts dis engaged position. - '2. A pressure switch comprising an element movable in response to a pressure condition, spring means opposing such movement and ad justable to vary the range of operation of the switch, a pivoted member in the path of said ele 15 ment, over-center spring means connected to said member and adjustable to vary the differential or operation of said switch, a contact arm pivoted on said member, biasing means for said arm at the contact side of its pivotal mounting, and a 20 stoplengaging said arm at the opposite side of its pivotal mounting to. cause rotation of said ‘arm against said biasing means to contacts dis engaged position in response to movement of said member by said element. 25 3. A pressure switch comprising an element 10 movable in response to a pressure condition, spring means opposing such movement and ad justable to vary the range of operation of the switch, a pivoted member operatively connected 30 to'said element, a compression spring intercon meeting said member and a relatively ?xed part and movable through its dead center position. during movement of_ said member to extreme positions, said compression spring being adjust 36 able to vvary the differential of operation of the switch, spring means opposing moving of said member by said element, a contact arm pivoted on said member, spring means biasing said arm at the contact side of its pivotal mounting, and 40 a stop engageable with said arm at the opposite side of its pivotal mounting to effect rotation thereof to its contacts disengaged position. 4. A pressure switch comprising, an element movable in response to a pressure condition, spring means opposing such movement and ad justable to vary the range or operation or the switch, a pivoted member operatively connected to said element, a compression spring intercon necting said member and a relatively ?xed part and movable through its dead center position during movement of said member to extreme positions, said spring being adjustable to vary the di?erential of operation of the switch, spring 10 means opposing moving of said member by- said element, a contact arm pivoted on said member, spring means biasing said arm at the contact side of its pivotal mounting, and a stop engageable with said arm at the opposite side of its pivotal mounting to e?ect rotation thereof to its con tacts disengaged position, the spring means bias ing said member and said arm being su?icient to overcome the bias of said compression spring when in the contacts disengaged position so as 20 to e?ect return of said member and engagement of the contacts when the element is moved by the ?rst mentioned spring means in response to a reduction in the pressure condition. 5. A pressure switch comprising an element 25 movable in response to a pressure condition, spring means opposing such movement and ad justable to vary the range of operation of the switch, a pivoted member, a compression spring disposed between the free end of said member and 30 a relatively ?xed part and movable through dead center position during movement of said member by said element, said compression spring being adjustable to vary the differential of operation of the switch, a contact controlling arm pivoted 35 on said member, biasing means for said arm at one side of its pivotal mounting, and a stop en gaging the opposite side of said arm during move ment of said member by said element to e?'ect rotation of said arm against said biasing means 40 to actuate the switch contacts. \ CARL A. SCHAEFER.