US 3089009 A
Description (OCR text may contain errors)
y 7, 1963 T. Y. KORSGREN, SR 3,089,009
ACTUATING MEANS FOR A HERMETICALLY SEALED SWITCH OR THE LIKE Filed Sept. 2, 1959 2 Sheets-Sheet 1 FIG. 1
INVENTOR. Theodore Y. Korsgren, Sr.
ATTORNEYS y 7, 1963 T. Y. KORSGREN, SR 3,089,009
ACTUATING MEANS FOR A HERMETICALLY SEALED SWITCH OR THE LIKE Filed Sept. 2, 1959 2 Sheets-Sheet 2 ii i HG. 6
INVENTOR Theodore Y. Korsgren,Sr.
ATTORNEYS United States Patent Ofilice 3,089,009 Patented May 7, 1963 3,089,009 ACTUATKNG MEANS FOR A HERMETICALLY SEALED SWITCH OR THE LIKE Theodore Y. Korsgren, Sr., Woodbury, Comm, assignor to Haydon Switch, line Waterbury, Conn., a corporation or Connecticut Filed Sept. 2, 105?, Ser. No. 837,670 Claims. (Cl. 200-83) This invention relates to actuating means for hermetically sealed devices, such as switches and, more particularly, to an actuator and hermetically sealed casing adapted to prevent uncontrolled variations in the operating characteristics of the actuator on a device mounted within the casing when variations occur in the ambient pressure.
Generally a hermetically sealed switch consists of the switch itself, perhaps of the snap-action type, mounted within a fluid-tight casing and engaged by an actuator extending through an opening in the casing. The actuator is usually supported in the opening by a flexible seal which prevents entry of fluid into the casing through the opening but permits axial movement of the actuator. By applying a force to the end of the actuator which is usually exposed on the outside of the casing, the actuator may be moved through the opening in its flexible seal to actuate the switch mounted within. In many instances this force may be applied by means of a slowly rotating cam or similar device, if periodic, carefully controlled actuation is desired.
Such hermetically sealed switches, and particularly those of the snap-action type are quite often employed in the electrical circuits of aircraft, underwater equipment, and other devices where the switch is subjected to wide variations in ambient pressure, and in more conventional uses they are subjected to the ordinary changes in atmospheric pressure. Whatever may be the magnitude of such pressure changes, they have a real and may possibly have a critical effect upon the operating characteristics of the switch as a whole and in particular upon the actuating force required to depress the actuator to the point where the switch is actuated and the distance through which that force must act. If the ambient pressure around the switch increases, the flexible seal surrounding the actuator in the opening in the casing is depressed inwardly since the pressure within the hermetically sealed casing remains constant. This also causes the actuator mounted in the seal to move inwardly to a new normal position. The force required to depress the actuator to the point of actuating the switch, and the distance through which it must act, are thereby lessened correspondingly. Similarly, if the ambient pressure decreases, the flexible seal and the actuator move outwardly and a greater actuating force acting through a greater distance is then required.
In a sensitive switch such as one of the snap-action type, such variations in the operating characteristics of the switch actuator in response to changes in ambient pressure may not be tolerable. For example, when a switch is to be actuated by a slowly revolving cam it may be quite necessary that the force exerted by the cam, and the distance through which that force must act, be of a predetermined value regardless of the ambient pressure. Otherwise the switch may not be able to be actuated at a precise time. It is the purpose of the present invention therefore, to provide actuating means for a hermetically sealed switch which permits accurate control and actuation of the switch even though the actuating means may be subjected to wide variations in ambient pressure.
The invention contemplates the use of a switch-actuating member in combination with a pressure compensating member each extending axially into an opening in a switch casing. A flexible seal is provided to hermetically seal the opening and support the aforementioned members in the opening through which each extends and permit substantially axial movement of each member through the opening. Linkage means is mounted on the casing and is engaged by the switch-actuating member and by the pressure compensating member. The linkage means is so constructed and arranged with respect to the arrange ment of the switch-actuating member and the pressure compensating member that the moving effects of the latter members on the linkage means are subtractive. That is the pressure compensating member is adapted to exert a force on the linkage means opposite to the force exerted thereupon by the switch-actuating member. Within the casing is a switch adapted to be actuated by substantial movement of the linkage means.
In this novel design, the switch thus may be elfectively isolated from variations in ambient pressure by the linkage means, the switch-actuating member and the pressure compensating member. Through this linkage the effects of any change in the ambient pressure may be cancelled out or accurately controlled and operation of the interior switch may remain unaffected thereby. Though the invention finds its widest use with hermetically sealed snapaction switches, it may also be advantageously employed with other types of switches or with virtually any hermetically sealed unit actuated through a flexible seal.
Certain preferred embodiments of the invention are described in detail hereinbelow with reference to the accompanying drawing, wherein FIG. 1 is a plan view of the switch casing;
FIG. 2 is an elevation partly broken away showing the construction of the actuating means and the linkage means which in this embodiment is a pivoted rocker arm member;
FIG. 3 is a section of the rocker member taken along line 3-3 of FIG. 2;
FIGS. 4 and 5 are top plan and elevational views, respectively of a second form of the invention; and
FIG. 6 is an enlarged, fragmentary cross-sectional view taken generally on line 66 of FIG. 4.
Referring first to FIGS. 1 and 2, the embodiment of the invention there shown comprises a metallic casing 10 adapted to be closed at one end by a closure member 11 through which extend suitable electrical terminals 12, 13 and 14, each insulated from the casing, and an evacuating tube 15. A switch or other device S to be sealed in the casing 10 is supported on mounting pins 16 and 17 which extend through the lower portion of the casing. Since the design of the switch or other device is not included in the scope of the present invention it is not shown in detail in the drawing. For the purposes of this description, it need only be stated that the switch is mounted on the pins 16 and 17, the switch poles are electrically connected to the terminals 12, 13 and 14, and the switch i positioned in the casing to be actuated by the actuating means described hereinbelow. After assembly, an inert gas may be supplied to the casing through the tube 15 and the tube may then be pinched as shown to seal the casing.
Two circular openings 18 and 19 of equal diameter are located in the top of the casing 10 and are defined respectively by flanges 20 and 21. Bonded securely to the flange 20 defining the opening 18' is a first flexible silicone rubber seal 22 which prevents the passage of any fluid through the opening 18 to the interior of the casing. A switch-actuating member 23 is disposed substantially axially in the opening 18 and is supported by and bonded to the flexible seal 21 in such a manner that the member 23 may be moved substantially axially with respect to the opening 18'. Its upper end is exposed on the outside of the casing to provide an abutting surface 24 adapted to receive the switch actuating force. The opening 19 is hermetically sealed by a second flexible silicone rubber seal 25 which is bonded to the flange 21 defining the hole. Disposed substantially axially in the opening 19 and bonded to the seal 25 is a pressure compensating member 26 which does not (though it could) extend completely through the flexible seal 25. It, like switch-actuating member 23,- is adapted to be moved substantially axially with respect to opening 19.
Referring now to FIGS. 2 and 3, a cylindrical pin 27 extends completely through the casing and is held in place by shoulders 28 and 29 on opposite outer surfaces of the casing. These shoulders effectively seal the holes in the casing through which the pin 27 extends. Pivotally mounted on the pin 27 within the casing 10 is a rocker arm 30 including a cylindrical journal portion 31 which fits coaxially over the pin 27 and is abutted on either end by the inside surface of the walls of the casing 10. The.
body of the rocker arm 30 extends outwardly from the journal portion 31 to each side as shown. It is provided on its lower face with actuating surfaces 32, one of which is adapted to engage the switch mounted in the housing to actuate the switch when the rocker arm is pivoted in one direction. The rocker arm 30 is positioned so that the switch-actuating member 23 and the pressure compensating member 26 engage opposite end sections thereof on opposite sides of the pivotal mounting. Any substantially axial movement imparted to either of the members 23 and 26 causes pivotal movement of the rocker arm 30.
-When a downward force is exerted on the abutting surface 24 of the switch-actuating member 23, the member 23 is moved downwardly and the flexible seal 22 flexes inwardly. This causes the rocker arm 30 to be pivoted in a counterclockwise direction about the pin 27 as seen in FIG. 2. As a result the switch is actuated by movement of one of the actuating surfaces 32 of the rocker which engages it. The pressure compensating member '26 moves upwardly and the flexible seal 25 is forced outwardly.
The previously discussed effects of ambient pressure on the operating characteristics of the described actuating mechanism are as follows. An increase in ambient pressure, for example, will cause an inward force to be exerted substantially axially upon the switch-actuating member 23 proportional to the area of the opening 18, and a corresponding force will be exerted upon the pressure compensating member 26 proportional to the area of the opening 19. These forces act upon opposite ends of the rocker arm 30 thus exerting subtractive turning forces thereon about the pin 27. If it is desired to eliminate entirely any axial movement of the switch actuating member 23 in response to the ambient pressure change, the openings 18 and 19 are made equal in area and the member-s 23 and .26 are locatedat equal distances from the axis of pin 27 on opposite ends of the rocker arm 30. The turning forces exerted by an increase in ambient pressure would then not only be subtractive but would cancel one another out and would have no effect on the linkage as a whole.
If it is desired to permit some controlled movement of the actuating member 23 in response to a change in ambient pressure, the area of the openings 18 and 19 and/ or the relative distances of the members 23 and 26 from the pin 27 may be chosen accordingly.
In the form of the invention shown in FIGS. 4-6, a rocker arm 40 is mounted outside the switch casing 41, to enable a simplification of manufacturing procedures. The housing 41 is provided with openings 42, 43, advantageously of equal size, which are closed off by seals 44, 45 of silicone rubber mounting rigid members 46, 47. For convenience of reference, the members 46, 47 may be referred to as actuating and compensating members, re-
spectively, it being understood, however, that either member may be used for either purpose.
As shown in FIG. 4, the members 46, 47 have portions 48, 49 extending upward from the tops of the seals and portions 50, 51 exposed below the seals and engaging a lever 52 forming part of a switch actuating linkage, for example. When the actuating member 48 is depressed the lever 52 is pivoted to effect the desired operation of the switch operating linkage.
In the second illustnated form of the invention, the actuating and compensating members 48, 49 are provided adjacent their upper ends with grooves 53 adapted to receive snap rings 54. Below the snap rings are Washers 55 and below the washers is the rocker arm 4%), the op-* posite ends 56, 57 of which are received on the members 48, 49. The rocker arm 40 has a center portion 58 in the form of an inverted V, which is received over and supportedby aknife edge 59, forming part of a bracket 60 mounted on the housing 41. Advantageously, the endsof the rocker arm 40 are provided with knife edges 6-1, 62 positioned to bear against the shoulder-like lower surfaces of the washers 55.
As shown best in FIG. 6, the members 48, 49, rocker 7 arm 40 and related parts are so proportioned that the rocker arm is held inplace on the knife edge 59 by inward (downward) force exerted by the members 48, 49. Such inward force is present at all times, in the absence of asubstantially greater pressure inside the housing than without.
In the device of FIGS. 4-6, the actuating mechanism is maintained in a condition of equilibrium, regardless of ambient pressure variations, through the rocker arm 40, substantially in the same manner as described in connection with the embodiment of FIGS. 1-3. The device of FIGS. 4-6 is desirable because of its substantial simplicity, and may be used to advantage where exposure of the compensating linkage to the atmosphere is not undesirable.
It will be readily apparent that numerous variations may be made in the design of this apparatus without departing from the scope of the invention. The scope of the invention should not therefore be limited to the embodiment set forth above but only to the extent set forth in the following claims.
1. 'A hermetically sealed switch assembly, comprising a casing adapted to be hermetically sealed, a switchactuating member and a pressure compensating member each extending into an opening in said casing, a flexible seal movably supporting each of said members in the opening through which each extends and hermetically sealing that opening from ambient pressure, said flexible seal permitting axial movement of each member in the opening through which each extends, said switch actuating member extending outward from said casing and being exposed for actuating engagement, and a linkage means mounted on said casing and normally engaged by said switch-actuating member and said pressure compensating member, said linkage means being so constructed and arranged that movement of the switch-actuating member in one direction relative to the casing moves the linkage means in a first direction and movement of the pressure compensating member in said one direction relative to the casing moves the linkage means in a direction opposite said first direction, and said linkage means being adapted to engage and actuate a switch mounted in said casing upon said linkage means being moved a predetermined distance by said switch actuating member.
2. A hermetically sealed switch assembly, comprising a casing adapted to be hermetically sealed, a switch-actuating member and a pressure compensating member extending into respective openings in said casing, a flexible seal movably supporting each of said members in its opening and hermetically sealing that opening from ambient pressure, the flexible seals permitting axial movement of the members into the openings, said switch actuating member extending outward from said casing and being exposed for actuating engagement, and a pivot member pivotally mounted on said casing, said switchactuating member and said pressure compensating member engaging said pivot member such that movement of said switch actuating and compensating members causes pivotal movement of the pivot member, said switch-actuating and compensating members being adapted to exert opposite turning forces on the pivot member when both are urged inwardly relative to said casing, and said pivot member being adapted when substantially displaced by said switch actuating member to actuate a switch mounted in the casing.
3. A switch assembly according to claim 2 where the openings in said casing sealed by the flexible seals are substantially equal in area and said pivot member is connected to said actuating and compensating members at points substantially equidistant from the pivot axis of said pivot member.
4. A switch assembly according to claim 2 wherein the pivot member is a rocker arm, and the turning forces exerted on the rocker arm by the switch-actuating member and the pressure compensating member are exerted on opposite ends of the arm and at equal distances from the pivotal mounting thereof.
5. In a switch assembly adapted to be hermetically sealed, a switch-actuating member and a pressure compensating member extending into respective openings on one side of said casing, said members being movable along substantially parallel axes and said openings being substantially equal in area, a flexible seal movably supporting each of said members in its opening and hermetically sealing that opening from ambient pressure, the flexible seals permitting substantially axial movement of the members into the openings, said switch actuating member extending outward from said casing and being exposed for actuating engagement, and a rocker arm pivotally mounted on said casing, said switch-actuating member and said pressure compensating member being engageable with opposite ends of said rocker arm on each side of and equidistant from the pivotal mounting such that any substantially axial movement of said members causes pivotal movement of the rocker arm, the pivotal movement caused by axial movement of said compensating member being opposite to pivotal movement caused by axial movement of said switch-actuating member, and said rocker arm being adapted when pivotally moved a predetermined distance in a predetermined direction by said switch actuating member to actuate a switch mounted in the casing.
6. A hermetically sealed device adapted for external actuation, comprising a casing, a device to be actuated mounted within said casing, said casing having a pair of openings, means sealing off the openings including actuating and compensating members connected to said device, and means interconnecting said actuating and compensating members whereby ambient pressure induced forces applied to one member tend to balance ambient presure induced forces applied to the other member, said interconnecting means being a rocker arm mounted on the outside of said casing for pivotal movement.
7. The device of claim 6, which includes means mounted on said casing between said members forming a knife edge, and said rocker arm is supported by said knife edge.
8. A hermetically sealed device adapted for external actuation, comprising a casing, a device to be actuated mounted within said casing, said casing having a pair of openings, means sealing off the openings including actuating and compensating members connected to said device, and rocker means interconnecting said actuating and compensating members whereby ambient pressure induced forces applied to one member tend to balance ambient pressure induced forces applied to the other member, said device to be actuated comprising an actuating element mounted for pivotal movement relative to said casing, said actuating and compensating members being asymmetrically located with respect to the pivot axis of said actuating element, said pivot axis being located toward one side of said casing, one of said compensating and actuating members being adapted to engage said actuating element relatively close to said pivot axis and the other of said members being adapted to engage said actuating element relatively farther away from said pivot axis.
9. The device of claim 8, in which said compensating and actuating members are generally cylindrical in shape and include exposed portions extending outwardly from said casing and exposed to the ambient atmosphere, said exposed portions including shoulder-like portions, said shoulder-like portions engaging said rocker means.
10. The device of claim 9, in which said rocker means is provided at opposite ends with knife edges, said knife edges engaging the shoulder-like portions of said actuating and compensating members.
References Cited in the file of this patent UNITED STATES PATENTS 2,431,801 Gibson Dec. 2, 1947 2,436,958 Eisenberg Mar. 2, 1948 2,492,675 Yeida Dec. 27, 1949 2,595,846 Hall et al May 6, 1952 2,890,305 Gutkowski June 9, 1959 2,950,373 Grover et al. Aug. 23, 1960 FOREIGN PATENTS 307,059 Germany Oct. 17, 1919