US3829637A

US3829637A - Limit switch having mechanism to eliminate unwanted reactivation thereof

Info

Publication number: US3829637A
Application number: US00320326A
Authority: US
Inventors: J Kilcoin
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1973-01-02
Filing date: 1973-01-02
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: CA1006894A

Abstract

A lever operated rotary limit switch for indicating when a device reaches a limiting position. The switch includes a housing having first and second portions. A motion converter is at least partially enclosed within the first portion of the housing. The converter includes a lever having one end adapted to engage the device which will move the lever, and a shaft assembly which has one portion thereof attached to the other end of the lever and another portion thereof for providing a standard switch motion in a first and a second direction upon a respective activation and deactivation movement of the lever by the device. A switch assembly is enclosed within the interior of the second portion of the housing. The switch assembly has cooperating contacts and means for opening and closing them. Activating means are provided for coupling the standard switch motion of the motion converter to the operating means of the switch assembly. Detent means in the form of a spring loaded ball or similarly shaped member is used to engage a groove in the other portion of the motion converter during deactivation movement in the second direction of the lever so as to prevent the lever from overshooting its zero or neutral position and from gaining sufficient potential energy to swing back in the activated direction thereby causing an unwanted reactivation of the limit switch.

Description

United States Patent [191 Kilcoin Aug. 13, 1974 LIMIT SWITCH HAVING MECHANISM TO ELIMINATE UNWANTED REACTIVATION THEREOF [75] Inventor: John Augustine Kilcoin, Normal, Ill.

[73] Assignee: General Electric Company, New

York, NY.

22 Filed: Jan. 2,1973

[21] App]. No.: 320,326

[52] US. Cl. 200/47, 74/107 [51] Int. Cl. H0lh 3/16 [58] Field of Search 200/47; 74/107 [56] References Cited UNITED STATES PATENTS 3,252,345 5/1966 Russell ZOO/47 X 3,539,738 11/1970 Bowen et al. 200/47 Primary Examiner-Herman Hohauser Attorney, Agent, or Firm-S. A. Young; P. L. Schlamp; R. G. Simkins [57] ABSTRACT A lever operated rotary limit switch for indicating when a device reaches a limiting position. The switch includes a housing having first and second portions. A motion converter is at least partially enclosed within the first portion of the housing. The converter includes a lever having one end adapted to engage the device which will move the lever, and a shaft assembly which has one portion thereof attached to the other end of the lever and another portion thereof for providing a standard switch motion in a first and a second direction upon a respective activation and deactivation movement of the lever by the device. A switch assembly is enclosed within the interior of the second portion of the housing. The switch assembly has cooperating contacts and means for opening and closing them. Activating means are provided for coupling the standard switch motion of the motion converter to the operating means of the switch assembly. Detent means in the form of a spring loaded ball or similarly shaped member is used to engage a groove in the other portion of the motion converter during deactivation movement in the second direction of the lever so as to prevent the lever from overshooting its zero or neutral position and from gaining sufficient potential energy to swing back in the activated direction thereby causing an unwanted reactivation of the limit switch.

15 Claims, 7 Drawing Figures Pmmww 3.829.637

FIG 2,

FIG. 9

20 FIG. 5 v

LIMIT SWITCH HAVING MECHANISM TO ELIMINATE UNWANTED REACTIVATION THEREOF BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to limit switches having means for preventing unwanted reactivation thereof after the switch has been deactivated.

2. Description of the Prior Art A prior art limit switch of the type described in US. Pat. No. 3,539,738 Bowen et al, is so designed that it can be readily adapted for use with diverse device motions by slightly modifying the limit switch. Such a limit switch includes a motion converter for changing the activating motion of a device, which device is mechanically coupled to the motion converter, to a standard vertical reciprocating switch motion. The device motion can be, for example, either rotary or horizontally reciprocative.

When the device motion is rotary, the motion converter consists of a shaft, a lever attached to one end of the shaft, and a cam attached to the other end of the shaft. When the lever is turned in an activating direction by the device, the cam rotates and in a downward thrust depresses means for actuating a contact switch module so as to open a pair of normally closed contacts or close a pair of normally open contacts within the switch module.

When the lever is released or turned by the device in the deactivating direction, the cam so turns as to allow the contacts of the switch module to assume their normal condition.

If the cam is so shaped and positioned on the shaft that only clockwise movement of the shaft will cause the cam to activate the actuating means, then once the lever is released and the actuating means is deactivated, the lever swings counter clockwise toward its vertical normal position gaining kinetic energy. The kinetic energy at the vertical normal position is maximum and carries the lever onward in the counter clockwise direction until all the kinetic energy is converted to potential energy. At this point the lever again begins to move in the clockwise direction and past the vertical normal position so as to cause a reactivation of the contacts of the switch module. In this manner the lever can swing back and forth two or three times until the oscillations are dampened out. This dampening oscillatory movement of the lever can cause repeated unwanted reclosure of the limit switch, and if the switch is energizing or triggering a digital system, a motor starter or a solenoid, a serious malfunction may well result. Also such unnecessary repeated closures of the switch contacts, exposes these contacts to additional arcing thereacross and ultimate early destruction thereof.

Similarly, if the cam is so shaped and positioned on the shaft that only counter clockwise movement of the shaft will cause the cam to activate the actuating means, then again, once the lever is released and the actuating means is deactivated, the lever swings in the clockwise direction overshooting its vertical normal position resulting in the above described dampened oscillations and unwanted disadvantages previously described.

Furthermore, if the cam is so shaped and positioned on the shaft that either a clockwise or counter clockwise movement of the shaft will cause the cam to activate the actuating means, then the lever may again develop a dampened oscillation upon being released by the device, if the lever developes sufficient kinetic energy and momentum to cause the unwanted overshoot. In this instance each overshoot in either direction results in activating the actuating means thus effectively aggravating the disadvantageous situation described above.

When the device motion is horizontally reciprocative, the lever is eliminated and the actuating means is activated by a cam attached to the shaft of the motion converter. In this instance, the shaft is longitudinally spring loaded, and when the device releases the shaft, the shaft springs back toward its normal horizontal position. However, if the shaft overshoots its normal horizontal position, the spring may acquire sufficient potential energy to again cause dampened oscillations of sufficient amplitude to result in unwanted repeated reactivation of the switch.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide a reliable limit switch which will not produce any unwanted reclosure or reactivation of its contacts after the switch has been deactivated.

It is a further object of this invention to provide a limit switch having means for preventing a motion converter within the switch from producing unwanted oscillations after the switch has been deactivated by a de vice, which oscillations would cause reclosure or reactivation of the limit switch thereby resulting in the introduction of a malfunction into a system embodying the limit switch.

It is another object of this invention to provide a lever operated rotary motion limit switch having means for preventing the lever from so overshooting its normal zero position after being released and thus avoiding a dampened oscillation which could cause repeated unwanted reactivation of the limit switch and an early destruction of the switch contacts due to repeated arcing thereacross.

Other objects of the invention will be pointed out and understood hereinafter.

SUMMARY OF THE INVENTION In accordance with one aspect of the invention there is provided a limit switch for indicating when a device reaches a limiting position comprising a housing. A motion converter is at least partially disposed within the housing and has a first part outside of the housing for engaging the device that will activate the limit switch. A second part of the motion converter includes a member having a camming section to provide a standard switch motion in a first and a second direction upon a respective activation and deactivation movement of said first part by the device. A switch assembly is disposed within the housing and has at least a first and a second contact along with operating means for moving .the first and second contacts into and out of engagement with one another. Actuating means in the form of a spherical actuator retained within a bushing is used to'couple the standard switch motion of the motion converter to the operating means of the switch assembly. Detent means are provided for engaging the motion converter during deactivation movement in the second direction of the motion converter.

More precisely the detent means, which is in the form of a spring loaded ball or body, is biased into a seated position in a groove which is located in another section of the member at that point where the motion converter should be in its normal Zero position.

According to a feature of the invention the motion converter is comprised of a shaft wherein the first part of the motion converter consists of a lever attached to one end of the shaft, and the second part of the motion converter consists of the cam attached to the shaft at or near another end thereof.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an assembled front sectional view of the limit switch detailing one embodiment of the invention;

FIG. 2 is an enlarged partial front sectional view of the limit switch of FIG. 1 showing a motion converter having a cam for engaging a spherical actuator and a spring loaded spherical detent;

FIG. 3 is an enlarged end sectional view of one embodiment of the detent means engaging the cam of the motion converter shown in FIG. 2;

FIG. 4 is another embodiment in partial perspective view of a differently shaped detent means engaging the cam shown in FIG. 2;

FIG. 5 is an end view of the cam engaging the spherical actuator and detent means shown in FIG. 2 so positioned that the limit switch is activated only when the motion converter rotates counter clockwise;

FIG. 6 is an end view of the cam engaging the actuator and detent means shown in FIG. 2 so positioned that the limit switch is activated only when the motion converter rotates clockwise; and

FIG. 7 is an end view of the cam engaging the actuator and detent means shown in FIG. 2 so positioned that the limit switch can be activated when the motion converter rotates in either the clockwise or counterclockwise direction.

DESCRIPTION OF A PREFERRED EMBODIMENT 13 journaled on a protruding outer end thereof and adapted for rotary movement within a bore 14 of a housing 15.

Body portion 11 comprises a housing 16 having a cover 17 on one side thereof permitting access to the housing interior. Fastening means 18 extends through cover 17 into housing 16 to secure both cover 17 and a gasket 19 disposed therebetween. Housing 16 can be made to engage and be joined to housing in the manner described in U.S. Pat. No. 3,539,738.

Actuating means is provided comprising a sphere 20 which is centrally disposed in a recessed portion of a top surface of housing 16, and adapted for free, reciprocative movement therein by a retaining means including a cylindrical bushing 21. As the motion converter which may be disposed in head portion 10 includes means providing the standard switch motion, as hereinafter described, it may readily be seen that the actuating means including retained sphere 20 allows placement and orientation of the motion converter in a variety of positions relative to body portion 11. The spherical actuator 20 provides a common actuating surface in each of the positions so that the movement coupled to a switch assembly within housing 16 is in all cases identical.

Housing 16 has a bore 22 within which cylindrical bushing 21 and spherical actuator 20 are disposed. Bore 22 communicates at one end thereof with an interior cavity 23 within which is mounted a switch assembly 24. A housing 25 of assembly 24 abuts a rear surface 26 of cavity 23 and is secured to at least one projection 27 of housing 16 by a screw 28.

A second bore 29, coaxial with bore 22, provides for communication between cavity 23 and an external surface 30 of housing 16 and is provided with a threaded section 31 adapted to receive a standard conduit.

Switch assembly 24 may be the same as described in U.S. Pat. No. 3,539,738, and may include any desired contact configuration, such as normally-opened or normally-closed contacts or any combination thereof, electrical connection being made to the stationary contacts of these combinations by means of terminals 32. Electrical leads may be soldered or otherwise secured to terminals 32 and drawn through bore 29 and the conduit inserted therein to any device capable of using the indication provided by switch assembly 24.

Movable contacts in switch assembly 24 are actuated by means of a reciprocative plunger 33 which extends into cylinder bushing 21. Spherical actuator 20 engages plunger 33 through the medium of a gasket seal including a diaphragm 34 which completely surrounds plunger 33 and an O-ring surface 35 which is compressed in assembly between bushing 21 and housing 25.

In one embodiment of switch assembly 24 suitable for use in the body portion 11 of this invention there is shown a normally open switch arrangement in FIG. 1. Housing 25 is comprised of Bakelite or other insulating materials which has disposed in an interior cavity 36 thereof a contact arrangement. Vertically positioned stationary contacts 37 have disposed therebetween a movable contact carrier 38 attached to reciprocative plunger 33. Movable contact carrier 38 has a contact bridge 39 attached thereto, wherein movable contacts 40 are fastened to the outer edges of contact bridge 39 so as to be in juxtaposition with stationary contacts 37. A spring 41 attached to carrier 38 normally maintains carrier 38 and plunger 33 in such a raised position that movable contacts 40 do not engage stationary contacts 37. As plunger 33 is depressed due to actuation by sphere 20, movable contacts 40 are forced into engagement with stationary contacts 37.

It is to be clearly realized that the invention is not limited to the described switching mechanism and indeed may be used with a variety of switch assemblies, the only requirements being that the assembly fit within cavity 23 of housing 16 and that it have a reciprocative plunger which can be inserted into bushing 21.

The construction of body portion 11 just described provides many advantages in addition to use with diverse motion converters. For instance, the contacts within switch assembly 24 may be completely protected from the ambient by first sealing the exterior of housing 25 with a suitable sealant, such as an epoxy material. Switch assembly 24 may then be installed into housing 16 by means of a screw 28 with the gasket seal blocking any access to cavity 23 through bore 22. After securing suitable electrical leads to terminals 32 and extending them through bore 29, the entire cavity 23 may be filled with a suitable potting compound. Thereafter, the seal may be completed by replacing gasket 19 in cover 17 and securing them by means of fastening means 18.

The motion converter shown in FIGS. 1 and 2 is known as a lever operated rotary motion converter and generallyconverts a rotary motion of an operating shaft to a standard reciprocative switch-operating motion. Included within housing is a general cavity 42 which opens adjacent spherical actuator in the assembly. A cylindrical projection 43 on housing 15 defines a cylindrical recess 44 in cavity 42. Extending through one side of housing 15 and into cavity 42 is a first bore 46 and coaxial therewith in a rear wall 47 of cavity 42 is a second bore 48. Operating shaft 12 is rotatably journaled within bore 48 and a cylindrical sleeve 49 is disposed within bore 46. Affixed to an outwardly projecting portion of shaft 12 is lever 13 carrying a pinned roller 50 for contact with the device with which the limit switch is associated. A seal 51 is compressed between cylindrical sleeve 49 and an annular groove 52 in shaft 12 and seals cavity 42 against the ambient.

Removably keyed upon a triangular shaft section 52 of operating shaft 12 is a member 54, which member is comprised of a plastic-like, metallic or any other suitable material having a camming section 55 joining detent section 56 of relatively smaller diameter than that of camming section 55. Member 54 is maintained in position against a surface 57 of shaft 12 by means of a circular spring 58 abutting the member and rear wall 47 of cavity 42. As can be seen from an inspection of FIGS. 5, 6 and 7, member 54 may be placed in any one of three positions, depending upon the expected motion of the device with which the limit switch is to be used. Camming section 55 of member 54 has a generally circular surface 59 and two

camming surfaces

60 and 61. When member 54 is placed upon shaft section 53 in the manner indicated in FIG. 5, rotation of operating shaft 12 in a counter clockwise direction, as viewed in the direction of the arrow 62 in FIG. 2, results in an eventual engagement between camming surface 60 and spherical actuator 20. When member 54 is in the position illustrated in FIG. 6, camming surface 61 provides for actuation of the switch assembly when shaft 12 is rotated in the clockwise direction. Likewise, FIG. 7 illustrates a position of member 54 for either clockwise or counter clockwise operation.

After the device (not shown) is used to activate the limit switch by causing lever 13 to rotate shaft 12, means is provided to cause the shaft and lever to return to a zero or initial normal position. This zero return means includes a section of shaft 12 having a flat cutaway portion 62a adjacent triangular shaft section 53. A plunger 63 is contained within recess 44 and is biased into engagement with shaft 12 by a spring 64 such that when plunger 63 is fully bearing against flat cutaway portion 62a, shaft 12 has returned to its zero position. However, due to the shape of the flat cutaway portion 620 and the therewith engaging bottom portion of plunger 63, as shaft 12 rotates in a direction to activate the limit switch, plunger 63 rises in recess 44 in such a manner as to continuously compress spring 64 up to the moment of the limit of the shaft rotation which is usually 45. This continuous compression of spring 64 causes a significant buildup in potential energy therein such that when lever 13 and shaft 12 are allowed to move in a direction to deactivate the limit switch, the potential energy in spring 64 and lever 13, is converted to sufficient kinetic energy to cause returning shaft 12 to rotate beyond and overshoot its zero position. In the instance when member 54 is positioned for clockwise and counter clockwise operation as shown in FIG. 7, this overshoot may result in reactivation of the limit switch. On the other hand if member 54 is positioned on shaft 12 as shown in FIGS. 5 and 6 for respective counter clockwise and clockwise operation the limit switch is not reactivated by this overshoot. However this overshoot causes a successive and somewhat dampened further overshoot in the activating direction which would cause reactivation of the limit switch. The resulting dampened oscillations will then effectively cause repeated unwanted reactivation of the limit switch.

Therefore in accordance with this invention, in order to prevent successive unwanted reactivation of the limit switch, there is provided in the head portion of the limit switch detent means for engaging the motion converter as shaft 12 rotates in a deactivating direction and for absorbing the kinetic energy of lever 13 and spring 64 while dampening a buildup in potential energy therein.

In one embodiment of the invention shown in FIGS. 2 and 3 the detent means is comprised of a spherical ball 65 which is retained partially within another recess 66 in housing 15. Recess 66 extends into cavity 42 and one end 67 of a spring 68 is fixed to the closed end of recess 66. The other end 69 of spring 68 presses against ball 65 and biases ball 65 toward the motion converter. In this embodiment detent section 56 of member 54 has a set of three

grooves

70, 71 and 72 extending parallel to the axis of shaft 12.

As shown in FIG. 5, groove 70 is so situated on detent section 56 that ball 65 will be biased into a seated position therein when member 54 is positioned on shaft 12 for counter clockwise operation (activation) and shaft 12 is in the deactivated zero (initial or normal) position. Similarly as shown in FIG. 6, groove 72 is so situated on detent section 56 that ball 65 will be urged therein when member 54 is positioned on shaft 12 for clockwise operation and shaft 12 is in the zero position. Likewise, as shown in FIG. 7, groove 71 is so situated on detent section 56 that ball 65 will be pressed therein when member 54 is positioned on shaft 12 for either clockwise or counter clockwise operation and shaft 12 is in the zero position. Thus, in accordance with the chosen type of switch actuation (clockwise only, etc.) ball 65 will press into the appropriate groove in the detent section of member 54 as the limit switch is being deactivated and lever 13 and spring 64 are imparting maximum kinetic energy to the rotating motion converter, and the combination of ball 65 and spring 67 will so absorb this energy as to prevent any significant overshooting of the zero position by, and oscillating movement of, the motor converter which would result in subsequent unwanted reactivation of the limit switch. The rounded shape of ball 65 and the generally curved and irregular shape of each of the grooves in de tent section 56 of member 54 advantageously result in a relative abrupt retraction of ball 65 into recess 66 as the motion converter rotates only part (i.e., of its full (i.e., 45) activation movement. in this manner spring 67 is only compressed for a portion of the rotating cycle and any unnecessary buildup in potential energy therein is avoided.

As shown in HQ. 4. spherically shaped ball 65 can be replaced by a generally cylintlrically shaped slide member 73 which has an end portion 74 that is semicylindrically formed to fit within one of the grooves in the detent section of member 54. End portion 74 of member 73 does provide a greater contact surface area with each of the grooves in detent section 56 of member 54 and with the walls of cavity 66 than does spherically shaped ball 65. This increase in contact surface can improve the effectiveness of the detent means in preventing unwanted reactivation of the limit switch by providing for the application of a greater friction force to the converter to absorb and dissipate the kinetic energy of lever 13 and spring 64.

It should also be noted that the grooves for engaging the detent means could be directly located on shaft 12, although this may not be entirely desirable since it will restrict the placement of the camming section on the shaft to insure proper cooperation between the actuating means and the detent means.

If the motion converter were of the reciprocative actuating type rather than the rotary actuating type, the problem of dampening oscillations in the shaft which would cause unwanted reactivation of the limit switch may still exist. These oscillations may be caused by a zero position return spring, which is responsible for repositioning the shaft in the deactivated zero (initial) position, if there is such a great buildup in energy in the spring that it causes the shaft to overshoot the zero position during deactivation movement in the motion converter.

Reactivation of the limit switch can be avoided when using the reciprocative type motion converter by placing a groove in the detent section of member 54 in a plane perpendicular to the axis of the shaft so as to engage the detent means when the shaft returns to the zero position.

If it is desired to change the position of member 54 on triangular shaft section 53, shaft 12 should be rotated to a position where plunger 63 can be reached via cavity 42 by a suitable tool which will be used to force the plunger to recede sufficiently into recess 44 to allow the shaft to be removed. Thereupon shaft 12 may be withdrawn from cavity 42 to allow member 54 to be repositioned on triangular shaft section 53 so that the mode of operation (i.e., clockwise only, counter clockwise only or clockwise/counter clockwise) of the limit switch can-be set.

While the above embodiments of this invention have been shown, it will be appreciated that modifications thereof, some of which have been noted in the preceding description, may readily be made by those skilled in the art. I therefore intend by the appended claims to cover the modifications specifically referred to herein as well as all other modifications which fall within the true spirit and scope of this invention.

What l claim as new and desired to secure by Letters Patent of the United States is:

l. A rotary limit switch for indicating when a device reaches a limiting position comprising:

a. a housing having first and second portions;

b. a motion converter at least partially disposed within the first portion of said housing, said motion converter including a lever having one end adapted to engage the device, and a shaft assembly having one portion thereof attached to the other end of said'lever and another portion thereof providing a switch motion from an initial position in a first direction upon an activation movement of said lever by the device;

c. a switch assembly disposed within the interior of the second portion of said housing, said switch assembly having at least a first and a second contact and operating means for moving said first and second contacts into and out of engagement with one another;

(1. means engaging said shaft assembly for moving said motion converter towards the initial position in a second direction simultaneously with a deactivation movement by said lever;

e. actuating means coupling the switch motion of said motion converter to said operating means of said switch assembly; and

f. detent means independent of and separate from said moving means for engaging said motion converter during deactivation movement in the second direction by said lever and for absorbing kinetic energy from and dampening a buildup in potential energy by said lever and said moving means to prevent a reactivation of said limit switch.

2. A limit switch according to claim 1 wherein said shaft assembly includes a shaft, and a member having a camming section predeterminably positioned on said shaft and shaped to be selectively operable in at least one mode of operation.

3. A limit switch according to claim 2 wherein the camming section of said member is positioned on said shaft assembly to cause said operating means to be actuated when said lever is moved in a clockwise direction.

4. A limit switch according to claim 2 wherein the camming section of said member is positioned on said shaft assembly to cause said operating means to be actuated when said lever is moved in a counter clockwise direction.

5. A limit switch according to claim 2 wherein the camming section of said member is positioned on said shaft assembly to cause said operating means to be actuated when said lever is moved in either a clockwise or a counter clockwise direction.

6. A limit switch according to claim 2 wherein said member has a detent section shaped to receive and engage said detent means when said lever is passing through a position of minimum potential energy and maximum kinetic energy.

7. A limit switch according to claim 6 wherein said detent means is comprised of a spring loaded body having a spring attached at one end to the first portion of said housing and a solid section having one end engaging an opposite end of said spring.

8. A limit switch according to claim 7 wherein the detent section of said member has at least one groove formed therein.

9. A limit switch according to claim 8 wherein the groove in the detent section of said member extends in a direction parallel to the axis of said shaft.

10. A limit switch according to claim 8 wherein another end of said solid section of said detent means is contoured to fit within approximately the whole of the groove in the detent section of said member.

11. A limit switch according to claim 7 wherein the solid section of detent means is comprised of a spherical body.

12. A limit switch according to claim 2 wherein said actuating means includes at least one spherical actuator protruding from the second portion of said housing, and retaining means for restraining movement of said spherical actuator outwardly of the second portion of said housing.

13. A limit switch according to claim 12 wherein said retaining means is comprised of a cylindrical bushing held within the second portion of said housing, said spherical actuator being retained within said bushing and capable of free reciprocative movement therein.

14. A limit switch according to claim 13 wherein said operating means of said switch assembly includes a reciprocative plunger extending therefrom and into said bushing for actuating said switch assembly when said spherical actuator depresses said plunger in response to actuating movement of said lever.

15. A limit switch for indicating when a device reaches a limiting position comprising:

a. a housing;

b. a motion converter at least partially disposed within said housing, said motion converter having a first part for engaging the device, and a second part providing a switch motion in a first and a second direction upon a respective activation and deactivation movement of said first part;

c. a switch assembly disposed within the interior of said housing, said switch assembly having at least a first and a second contact and operating means for moving said first and second contacts into and out of engagement with one another;

d. means engaging said second part of said motion converter for restoring said second part of said motion converter towards its initial position;

f. means independent of and separate from said restoring means for engaging said motion converter during deactivation movement in the second direction by said first part and for dampening buildup in potential energy by said restoring means to prevent a reactivation of said limit switch.

Claims

1. A rotary limit switch for indicating when a device reaches a limiting position comprising: a. a housing having first and second portions; b. a motion converter at least partially disposed within the first portion of said housing, said motion converter including a lever having one end adapted to engage the device, and a shaft assembly having one portion thereof attached to the other end of said lever and another portion thereof providing a switch motion from an initial position in a first direction upon an activation movement of said lever by the device; c. a switch assembly disposed within the interior of the second portion of said housing, said switch assembly having at least a first and a second contact and operating means for moving said first and second contacts into and out of engagement with one another; d. means engaging said shaft assembly for moving said motion converter towards the initial position in a second direction simultaneously with a deactivation movement by said lever; e. actuating means coupling the switch motion of said motion converter to said operating means of said switch assembly; and f. detent means independent of and separate from said moving means for engaging said motion converter during deactivation movement in the second direction by said lever and for absorbing kinetic energy from and dampening a buildup in potential energy by said lever and said moving means to prevent a reactivation of said limit switch.

15. A limit switch for indicating when a device reaches a limiting position comprising: a. a housing; b. a motion converter at least partially disposed within said housing, said motion converter having a first part for engaging the device, and a second part providing a switch motion in a first and a second direction upon a respective activation and deactivation movement of said first part; c. a switch assembly disposed within the interior of said housing, said switch assembly having at least a first and a second contact and operating means for moving said first and second contacts into and out of engagement with one another; d. means engaging said second part of said motion converter for restoring said second part of said motion converter towards its initial position; e. actuating means coupling the switch motion of said motion converter to said operating means of said switch assembly; and f. means independent of and separate from said restoring means for engaging said motion converter during deactivation movement in the second direction by said first part and for dampening buildup in potential energy by said restoring means to prevent a reactivation of said limit switch.