US 3144528 A
Description (OCR text may contain errors)
Aug. 11, 1964 PINO 3,144,528
ACCELERATION SWITCH Filed March 29, 1961 INVENTOR L one/s HA/a BY Maw, (04., M mwm ATTORNEYS United States Patent Office 3,144,528 Patented Aug. 11, 1964 3,144,528 I ACCELERATION SWITCH Louis Pino, Rego Park, N.Y., assignor toLeesona Corporation, Cranstou, R.I., a corporation of Massachusetts Filed Mar. 29, 1961, Ser. No. 99,232 4 Claims. (Cl. 20tl61.45)
This invention relates to an electrical switch, and more particularly, to an electrical switch which operates in response to acceleration forces.
Acceleration switches are well-known in the art. However, the prior art devices are subject to certain disadvantages. For example, it is difficult to make an adjustable acceleration responsive switch. Further, the prior art devices are subject to creeping action when subjected to vibration, which disadvantage precludes their use in certain installations.
Accordingly, it is an object of this invention to provide an improved electrical switch which is responsive to forces of acceleration.
It is another object of this invention to provide an adjustable electrical switch which operates in response to forces of acceleration.
It is a further object of this invention to provide an acceleration responsive switch which is simple in construction, easy to manufacture, and easy to adjust.
It is another object of this invention to provide an acceleration responsive electrical switch with a minimum of moving elements in which the primary element is purely rotational and is supported by bearings such that no creeping action of the switch components can occur when subjected to vibration.
It is another object of this invention to provide an improved acceleration switch which is encased in a sealed container with damping fluid, which switch when subjected to vibration experiences an effective damping action from the onset of angular movement of the acceleration responsive element, which damping action continues until the switch operation is completed.
Briefly, in accordance with one illustrative embodiment of this invention, an eccentric mass is mounted on a shaft and the shaft is journaled in one or more suitable bearings in a switch housing. An elongated substantially flat spring member, which may be in the form of a wire, is secured at its midpoint to the shaft to form a dual cantilever beam assembly. Advantageously, a pair of adjusting setscrews are providing in the housing in positions to engage portions of the eccentric mass and thus limit the arc of rotation of the eccentric mass. Also advantageously, a pair of adjustable insulating supports are provided in the regions of the ends of the spring member, which insulating supports have mounted thereon, suitable electrical contact pins. Preferably, the supports are rotatably mounted with their axes of rotation perpendicular to the plane of movement of the flat spring member. Advantageously, the contacts are mounted eccentrically on the supports such that rotation of the supports about their axes controls the positionof the contacts relative to opposite ends of the spring member. With this simple arrangement, both contacts can be moved into engagement with the spring member on'the same side of the spring member to define a normally closed switch. This embodiment is opened by the application of acceleration forces to the eccentric mass. These forces cause the mass to rotate, developing a torque which produces a stress in that portion of the spring member between the shaft and the one contact towards which the eccentric mass is rotating, which torque moves the opposite end of the spring member away from the other contact pin.
In another illustrative embodiment, the ends of the spring member may be placed on opposite sides of the 2 respective contact pins by bending the spring and/or rotation of the pin supports. In this embodiment, the switch will be normally open and in response to acceleration of the switch housing, the eccentric mass will rotate toward the one contact which normally engages the spring member, thereby developing a torque which produces a stress in one part of the spring which moves the other part of the spring into engagement with the other contact pin.
Advantageously, in either of these embodiments, the cantilever beam spring, or wire, determines the range of adjustments available to determine the magnitude of the forces required to actuate the switch. Within this range, the adjustment of the switch is achieved by positioning the switch contacts relative to the spring beam. Also advantageously, the entire switch assembly is hermetically sealed in a container which is filled with damping fluid to provide a damping action with respect to vibration.
These and various other objects and features of the invention will be more clearly understood from a reading of the detailed specification in conjunction with the drawing, in which:
FIGURE 1 is a side view in elevation of one illustrative embodiment of this invention with the cover removed;
FIGURE 2 is a View of FIGURE 1 taken in the direction of the arrow 2 with the side of the cover removed;
FIGURES 3 and 4 are side views in elevation of an embodiment of the invention which defines a normally closed switch and is shown in FIGURE 3 in its normal position and in FIGURE 4 in its operated position; and
FIGURES 5 and 6 show another illustrative embodiment of this invention which operates as a normally open switch, shown in FIGURE 5 in its normal position, and in FIGURE 6 in its actuated position.
Referring now to FIGURES 1 and 2, there is depicted one illustrative embodiment of this invention in which a housing 10 contains a suitable support member 12. The entire housing 10 is preferably hermetically sealed by a metal cover 13, shown in FIGURE 2, and contains a suitable nonconducting damping fluid. This damping fluid will damp out any externally applied vibrations which would otherwise prevent proper switch operation. Advantageously, this damping action will be continuous throughout the operation of the switch. A journal bearing 14 is mounted in the support member 12 and a shaft 16 is rotatably mounted in the bearing 14. An eccentric mass 18 is secured to the shaft 16 and this eccentric mass is advantageously in the form of a sector of a circle; for example, a semicircle. A pair of setscrews 20 and 22 are supported in suitable supports 24 and 26 respectively, on the support member 12. These setscrews are positioned so that their ends engage flat surfaces on opposite sides of the eccentric mass 18 and thus their adjustment controls the are through which the eccentric mass 18 may rotate. A dual cantilever beam spring 28 is preferably, though not necessarily, secured at its midpoint to shaft 16. Advantageously, this spring may be a wire of suitable diameter or it may be a flat spring having a relatively rectangular cross section, depending on the particular range of forces to which the switch is to be adjustable.
A pair of insulating supports 30 and 32 are rotatably mounted in support member 12 and these supports have switch contacts 34 and 36 respectively, mounted thereon. As best seen in FIGURE 2, the axes of supports 30 and 32 are perpendicular to the plane of movement of the eccentric mass 18. Thus the switch contacts 34 and 36 which are eccentricaly mounted on supports 30 and 32 respectively, may be positioned relative to the spring 28 by rotation of the members 30 and 32. Suitable conductors, not shown, may be connected to contacts 34 and 36 to connect the switch in the circuit to be controlled.
FIGURES 3 and 4 show side elevational views of an embodiment of this invention with the cover removed,
which embodiment is adjusted to operate as a normally closed switch, its normal position being shown in FIG- URE 3 and its operated position being shown in FIG- URE 4. As best seen in FIGURE 3, opposite ends of spring 28 are in contact with contacts 34 and 36. The eccentric mass 18 is in engagement with setscrews 20 while setscrews 22 is displaced from the flat surface of the mass 18. It is apparent that contacts 34 and 36 are exerting considerable stress on the spring 28 to produce the curvature in the spring 28, shown in FIGURE 3. When the embodiment of FIGURE 3 is subjected to any force of acceleration in the direction of arrow 40 in FIGURE 4, the eccentric mass or sector 18 will tend to rotate its axle 16 and move until sector 18 engages setscrew 22. This rotation of sector 18 develops a stress in spring 28 between the axle 16 and the contact pin 36. This stress will oppose the acceleration force applied to the mass 18. When a sufficient accelerating force is applied to the mass 18, it rotates to the position shown in FIGURE 4, in which position the spring 28 has moved away. from contact 34, thus opening the switch. The particular force required to open the electrical circuit between pin 34 and pin 36 will be determined for a given spring by the positions of pins 34 and 36, which positions may advantageously be adjusted by rotating the contact pin support members 30 and 32 respectively, by any convenient means, not shown.
FIGURES and 6 show another illustrative embodiment of this invention in side elevation, which embodiment acts as a normally open switch and is shown in its normal position in FIGURE 5 and in its actuated positionin FIGURE 6. The principal'distinction between the normally open embodiment of FIGURE 5 and the normally. closed embodiment of FIGURE 3 is the position of spring 28 relative to pin 34. In FIGURE 3, the spring is to the right of pin 34and in engagement with the pin,
While in FIGURE 5, the spring 28 is to the left of pin 34 and out of contact with this pin. When the embodiment of FIGURES 5 and 6 is subjected to an accelerating force in the direction of arrow 42 in FIGURE 6, the eccentric mass 18 will tend to rotate in the direction of arrow 43 and thus develop a stress in spring 28 between the axle 16 and contact pin 36. This stress will continue to develop to the limit of the applied force of acceleration or until the mass 18 engages the end of setscrew 22, whichever is first. Assuming that a suflicient accelerating force is applied to the switch, torque will be applied to the spring 28 until it engages contact pin 34 and thus completes the electrical circuit between contact pin 34 and contact pin 36. When the accelerating force is removed in each of the embodiments shown in FIGURES 4 and 6, the switch will return to its respective normal position as shown in FIGURES 3 and 5.
While I have shown and described certain illustrative embodiments of this invention, it is understood that the principles thereof may be applied to other embodiments without departing from the spirit and scope of this inven tion. For example, in FIGURE 3, the positions of the ends of spring 28 relative to contact pins 34 and 36, may be reversed and the switch will nevertheless open in re sponse to an accelerating force. For example, if the spring 28 in FIGURE 3 were placed on the opposite sides 4 of the pins 34 and 36, the switch would be normally closed and the switch would open at the point of contact between spring 28 and contact pin 36 in response to the acceleration forces in the direction of arrow 40 in FIG- URE 4.
What is claimed is:
1. An acceleration responsive electrical switch comprising a support member, a shaft rotatably mounted in said support member, an eccentric mass secured to said shaft, means normally maintaining said eccentric mass to one side of said shaft relative to the direction of the force of acceleration to be measured, said last-mentioned means including means for limiting the arc of rotation of said mass, spring means secured to said shaft and extending radially from said shaft, and contact means positioned in the path of said spring means to be engaged thereby during the rotation of said mass in response to an accelerating force.
2. A switch according to claim 1, wherein the contact means comprising one contact eccentrically mounted on a rotatably shaft, and the position of said contact means is adjustable relative to said spring means by rotating the shaft to determine the magnitude of acceleration force required to actuate said switch.
3. A switch according toclaim 1, wherein said contact means include a pair of contacts mounted on a dual cantilever spring comprising said spring means, and wherein v said contacts on said spring means engage said contact means in the region of opposite ends of said spring means.
4. An acceleration responsive switch comprising a support member, eccentric mass means rotatably mounted in said support member, contact spring means connected to said eccentric mass, means for limiting the arc of rotation of said mass, and contact mens mounted in the path of said spring means, wherein the position of the contact means is adjustable relative to said spring means to determine the magnitude of acceleration force required to actuate said switch and wherein said spring means extends radially in opposite directions from the axis of rotation of said mass, and wherein one end of said spring means nor-.
mally engages a first contact of said contact means and wherein the other end of said spring means is normally spaced from a second contact of said contact means, whereby rotation of said eccentric mass develops a stress in said spring means between said axis of rotation and said first-mentioned contact and causes said other end of said spring means to engage said second-mentioned contact, thereby defining an electrical path between said contacts.
References Cited in the file of this patent UNITED STATES PATENTS 1,175,062 Johnson Mar. 14, 1916 1,256,134 Joeck Feb. 12, 1918 1,855,581 Meade Apr. 26, 1932 2,731,526 Teague et al Jan. 17, 1956 2,761,031 McDonald Aug. 28, 1956 2,812,398 'Mickman Nov. 5, 1957 2,966,564 Cunningham Dec. 27,1960
FOREIGN PATENTS 1,200,346 France Dec. 21, 1959