US3675169A

US3675169A - Durable electrical switch

Info

Publication number: US3675169A
Application number: US156228A
Authority: US
Inventors: Rolland D Scholl
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1971-06-24
Filing date: 1971-06-24
Publication date: 1972-07-04
Anticipated expiration: 1989-07-04
Also published as: JPS4811572A

Abstract

A manually operated switch having a sealed cylindrical housing is controlled through a pivotable, radially extending external actuator member and contains a pair of magnetically actuated sets of reed contacts for connection to the electrical circuit with which the switch is associated. A pair of permanent magnets are carried on resilient arms within the housing whereby each may be shifted into an operative position relative to one of the sets of reed contacts upon flexing of the associated arm. The external actuator member is disposed on an axle which extends into the housing through a circular seal and bearing to connect with a parallel internal actuator that bears against either of the resilient arms according to the direction of pivoting. This enables external actuator movement to be transmitted into the housing in the form of purely rotational motion through the circular seal thereby simplifying sealing problems and minimizing wear to provide a compact rugged and long lived mechanism.

Description

United States Patent Scholl 1 July 4,1972

[72] inventor:

[52] U.S. [5i] int. Cl. [58] Field ofSearch...........................

..............335/205, 335/206 ..ll0lh 2l/80 .......33S/205, 206, 207

[56] 7 References Cited UNITED STATES PATENTS 3,l70,052 2/1965 Hajos ..335I20S X 3,268,684 8/1966 Keller et al........ "335/206 UX Primary ExaminerBernard A. Gilheany Assistant Examiner-R. N. Envall, Jr. Attorney-Charles M. Fryer et al.

[ ABSTRACT A manually operated switch having a sealed cylindrical housing is controlled through a pivotable, radially extending external actuator member and contains a pair of magnetically actuated sets of reed contacts for connection to the electrical circuit with which the switch is associated. A pair of permanent magnets are carried on resilient arms within the housing whereby each may be shifted into an operative position relative to one of the sets of reed contacts upon flexing of the as sociated arm. The external actuator member is disposed on an axle which extends into the housing through a circular seal and bearing to connect with a parallel internal actuator that bears against either of the resilient arms according to the direction of pivoting. This enables external actuator movement to be transmitted into the housing in the form of purely rotational motion through the circular seal thereby simplifying sealing problems and minimizing wear to provide a compact rugged and long lived mechanism.

9 Claims, 5 Drawing Figures Patented July 4, 1972 3,675,169

3 Sheets-Sheet 1 INVENTOR ROLLAND D. SCHOLL Patented July 4, 1972 3 Sheets-Sheet 2 INVENTOR ROL LAND D. SCHOLL a" g '5 ATZSRNEYS Patented July 4, 1972 3 Shun-lint 3 INVENTOR ROLLAND D. SCHOLL 7" fizz- M ATTORNEYS BACKGROUND OF THE INVENTION This invention relates to electrical switches and more particularly to the switches of the form which are contained within a sealed housing and which have a movable actuator member extending externally thereof.

In certain specialized usages, electrical switches must combine ease of operation with a capability for an extremely high number of repeated operations without failure. One example of such a switch usage is described in copending applicau'on Ser. No. l43,957 of Russell D. Page et al. for Electro-I-Iydr'aulic Touch Control System filed May I7, 1971 and assigned to the assignee of the present application. This copending application describes a system which uses manually operated switches to control electro-hydraulic motors which manipulate the earth moving blade of a motor grader vehicle. In this context, the electrical switches should be capable of being operated repeatedly over a very long period of time with high reliability while requiring a minimum of operator effort and diversion of attention. Moreover this must be achieved in adverse environmental conditions which may include extensive dust, vibration and exposure to sizable temperature variations and rough handling.

Existing switch constructions do not fully realize these desirable characteristics in contexts such as that discumed above. Most of the varied prior switch constructions were designed for operation in a relatively clean, stable and less abusive environment in indoor systems where the switch is either not subjected to extensive operations or else may readily be replaced by maintenance personnel without great inconvenience.

The severe working conditions described above make it highly desirable to utilize switches of the form in which elements other than an external actuator member are contained within a sealed housing. Preferably the external actuator is a pivoting element rather than a longitudinally sliding member, such as in a push button switch, since a pivotable support tends to be stronger and more durable under repeated use and does not actively assist the movement of dust, moisture or other damaging substances into the housing.

As heretofore constructed, switches of the form having a sealed housing with a pivoting actuator member extending outside the housing have been characterized by an inherent sealing problem which detracts from the ultimate durability of the switch over many cycles of operation. In particular the actuator member has been extended through an opening in the housing and since it must pivot, the opening must be somewhat larger than the actuator member itself. This in turn has required either a flexible diaphram type of seal or a sliding seal both of which have undesirably limited life under repeated operation. Such seals tend to develop imperfections after a period of use, which admit foreign substances into the housing. The problem has been aggravated as the forms of contacts heretofore used within the housing for performing the switching function are prone to damage from foreign matter which is admitted in this manner and have an undesirably limited life.

SUMMARY OF THE INVENTION The present invention provides a compact, sensitive electrical switch capable of sustained repeated operation under adverse environmental conditions. The switch includes a'sealed housing in which the pivotable actuator lever is wholly outside the housing and motion of the lever is transmitted into the housing solely through the axle to which the lever is pivoted. This arrangement requires only a circular rotary seal around the axle, such rotary seals having greater durability and reliability than sealing means which must accommodate to sliding motion. Within the housing, the switching functions are performed by one or more sets of reed switch contacts each of which is controlled by a magnet mounted on resilient means that may be flexed by oscillation of the rotary axle. Thus no short lived sealing means nor wear prone mechanical mechanisms are necesary.

Accordingly, it is an object of this invention to provide a compact, reliable, rugged and readily operated electrical switch having a very long life in terms of repeated operations and which retains these qualities while subjected to severe external environmental conditions.

The invention together with further objects and advantages thereof will best be understood by reference to the following description of preferred embodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. I is a perspective view of a portion of the operator's seat of a motor grader vehicle or the like showing switches in accordance with the invention mounted thereon for ease of control of powered elements of the vehicle;

FIG. 2 is a perspective view of one of the control switches of FIG. 1 shown disassociated from the other structure thereof;

FIG. 3 is a section view of the switch assembly of FIG. 2 taken along line 3-3 thereof;

FIG. 4 is a section view taken along line 4-4 of FIG. 3; and

FIG. 5 is a section view corresponding to FIG. 4 showing a modified internal construction for the switch assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a pair of switch assemblies ll and 12 are shown disclosed in a particular context which is exemplary of situations requiring electrical switches of unusual durability and ruggedness combined with ease of operation. In this example the two switches 11 and 12 are secured together in coaxial relationship and are disposed at the forward end of an armrest I3 of an operator's seat 14 of a motor grader vehicle of the form described in the above identified copending application Ser. No. 143,957 As described in detail in the copending application, the two switches l l and 12 are used to control electro-hydraulic mechanism for selectively raising and lowering either side of the blade of the motor grader while an adjacent knob 15 operates a potentiometer to control the rate of blade movement.

In this working context, switches should require only light pressure and slight movement of operating buttons 16 to minimize operator effort and diversion of attention from other control functions. Preferably, the switches should have a configuration which enables the operators hand 17 to rest comfortably on the arm rest 13 with the fingers extending partially around the switches ll and 12 so that each switch may be operated by a slight easy movement of an individual finger. The electrical circuits controlled by the switches ll and 12 are not further described herein inasmuch as the circuit mechanisms controlled thereby are described in detail in the above identified copending application and do not form a part of the present invention.

FIG. 2 shows a representative one of the switches [I removed from the other structure of FIG. I in order to better illustrate the switch construction. Switch 11 has a cylindrical housing 18 with an integrally formed end wall 19 closing one end and a circular disc 21 secured to the opposite end to complete the enclosure.

One end wall of housing 18, end wall 19 in this instance, is provided with a diametrically directed groove 22 in the exterior surface which extends to a flat area 20 of the housing to receive a linear external actuator lever 23 which supports control button 16 outward from the flat area. Lever 23 is supported by an axle pin 24 extending into the housing along the axis thereof as will hereinafier be described in more detail. Button 16 may be of essentially rectangular configuration with a cylindrical outer surface having transverse small grooves 26 to facilitate finger tip control and in this example is formed integrally with the actuator lever 23. Actuator lever 23 has a bore at the end opposite button 16 into which the end of axle 24 is received and is secured to the axle in radial relationship thereto by a set screw 27.

While this particular example of the invention utilizes the button 16 for fingertip control, it will be apparent that the switch may also be readily operated by providing a lengthier lever 23 which lacks such a button.

Groove 22 in the end wall of the housing is of slightly greater breadth than lever 23 to provide for a limited degree of pivoting movement of the lever. This provision of a groove 22 in the end wall 19 to receive lever 23 serves several useful purposes. The groove 22 defines high strength durable stops for limiting pivoting movement of the actuator member 23. ln addition, the disposition of the lever in the groove enables two or more of the switch assemblies 11 to be disposed in a coaxial column with each such assembly adjacent to another but without causing interference with motion of any of the externally situated actuator levers 23. Further, the necessary electrical conductor wires 28 may enter the housing 18 through an aperture 29 in the portion of groove 22 remote from lever 23 also without interfering with the placement of a series of such switches in proximity to each other. To provide for flexibility in the orientation of lever 23 and button 16, this example of the invention includes a second groove 22' in end wall 19 at right angles to the first groove 22.

Accordingly, the external actuator lever 23 is situated wholly outside of the housing 18 and motion of the actuator is transmitted into the housing solely in the form of angular motion of the axle 24 about its own axis. Considering now the mechanism through which angular motion of axle 2A is caused to operate switch contacts within the housing, reference should be made to FIGS. 3 and 4 in combination.

Referring initially to FIG. 3 in particular, end wall 19 of housing 18 has a stepped tubular reentrant section 31 extending inward in coaxial relation to axle 24 towards the opposite end wall defined by disc 21. Reentrant section 3] has a stepped bore including a first bore section 32 adjacent external actuator lever 23 in which an annular seal 33 is disposed. Seal 33 may be any of various forms of annular seal which prc vide for angular motion of a shaft encircled by the seal and in the present instance is a lip seal. Reentrant tubular section 31 of the housing has a second bore section 34 of reduced diameter into which a sleeve bearing 36 is disposed to journal axle 24 in housing section 31 while minimizing friction and wear. Axle 24 extends a short distance through bearing 36 towards disc 21 and an inner actuator member 37 is secured thereto to extend radially from the axle in parallel relationship to the external actuator lever 23. For purposes to be described, a pin 40 extends from the free end of inner actuator lever 37 in parallel relationship to axle 24.

Referring now to FIG. 4, a pair of encapsulated sets of

reed switch contacts

38 and 39 are disposed within housing 18 on opposite sides of axle 24 and inner actuator member 37. Each

such reed switch

38 and 39 may be of conventional construe tion and thus may have basic elements consisting of a closed tubular glass capsule 41 with a pair of flexible reeds 42 and 43 of magnetizable material disposed therein in an arrangement wherein the reeds overlap for a short distance and each connects with a separate conductor wire 28 at opposite ends of the capsule 41. As is understood within the art, reed switch contacts of this form may be opened or closed by appropriate movement of a permanent magnet in the vicinity as the behavior of the two reeds is influenced by the field of such a magnet. Several forms of reed switch, including normally open and normally closed forms, are available and each may be utilized in the context of the present invention. For purposes of example, the reed switches 38 and 39 shown in FIGS. 3 and 4 are of a normally open form in which the internal reeds 42 and 43 are slightly separated in the operlapping regions until such time as a magnet is brought into close proximity to the capsule 41 at which time the contacts close.

The switch capsules 4] are secured on an annular support 45 disposed adjacent end wall 19 and in coaxial relationship to re-entrant section 31. As best seen in FIG. 3, the annular region occupied by support 45 and capsules 41 is filled with a potting compound 50 to secure and protect the reed switches.

First and second magnets 44 and 46 are secured at one end of

angled leaf springs

47 and 48 respectively for selectively operating reed switches 38 and 39 respectively. The opposite end of each

spring

47 and 48 is secured to an associated one of a pair of circular springs 49 and 51 respectively which are in turn secured to the inner wall of housing 18 on opposite sides of the pin 40 which extends from the end of inner actuator lever 37. The two springs 49 and 51 exert opposite forces on pin 40 to establish a normal position for the pin and

actuator levers

37 and 23 at which the external lever 23 is centered in groove 22. At this position

magnet support arms

47 and 48 abut opposite sides of housing reentrant section 31 and position the associated magnets 44 and 46 adjacent

reed switch capsules

38 and 39 respectively but at sufficient distance therefrom that the reed switches remain inoperated until such time as the magnets are shifted from the normal rest position by movement of pin 40.

Thus, in operation, springs 49 and 51 nonnally hold

arms

47 and 48 against reentrant section 31 thereby holding the magnets 44 and 46 out of operative relationship with respect to

reed switches

38 and 39 respectively and also holding the external operator's button 16 in the centered position thereof. Upon movement of the operator's button 16 in one direction, such motion is transmitted by lever 23, axle 24, lever 37 and pin 40 to distort spring 49 and thereby shifi arm 47 towards reed switch 38. The resultant motion of magnet 44 into close proximity with the reed switch 38 causes the contacts 42 and 43 thereof to close as previously described thereby closing a circuit between the two associated leads 28. Upon release of the button 16 spring 49 restores the above described elements to the original position withdrawing magnet 44 from close proximity to reed switch 38 and opening the above described circuit. Motion of the operators button 16 in the opposite direction distorts spring 51 to move magnet 46 toward reed switch 39 in an essentially similar manner thereby closing the circuit associated with that reed switch.

Variations may be made in the detailed mechanism for transmitting oscillatory movement of axle 24 into appropriate movement of the magnets for operating the reed switches. FIG. 5 illustrates one such modification. The general construction of the switch ll of FIG. 5 is similar to that previously described except insofar as the magnets 44 and 46' which operate reed switches 38' and 39' respectively are attached to arms 47' and 48' respectively which are in turn secured to opposite ends of a U-shaped leaf spring 51 to form extensions of the ends thereof. The center of spring 51 is secured to the inner wall of housing 18' by a suitable screw 52 or the like and as in the previous instance the spring normally abuts the two arms 47' and 48' against opposite sides of reentrant section 31' of housing 18. The inner actuator lever 37' which extends radially from axle 24' is a triangular plate in this modification with a broad free end which spans the gap between arms 47' and 48 near the base of U-shaped spring 51. A pair of spaced pins 53 extend from the free end of actuator lever 37' to contact arms 47' and 48' respectively whereby turning of axle 24 in either direction causes one of the pins 53 to flex the adjacent leg of spring 51 and thereby shifts the associated one of the magnets 44' or 46' towards the associated reed switch 38' or 39' to operate the reed switch as previously described.

Thus modifications of the invention are possible and it is not intended to limit the invention except as defined in the following claims.

What is claimed is:

1. An electrical switch comprising:

a housing defining a chamber and having an aperture in one wall which communicates with said chamber,

at least one set of reed switch contacts disposed in said housing and having electrical conductors extending therefrom to the exterior surface of said housing, said contacts being of the form which may be caused to open and close by movement of a magnet in the vicinity thereof,

spring means disposed within said chamber of said housing and having a fixed portion and a movable portion,

a magnet secured to said movable portion of said spring means for movement between a normal position and a second position to operate said reed switch contacts,

an axle extending through said aperture of said housing, and

being movable angularly with respect thereto,

an inner actuator lever extending radially from said axle within said chamber of said housing and having means bearing against said spring means for flexing said spring upon angular movement of said axle to force said magnet from said normal position to said second position thereof, and

an external actuator lever extending radially from said axle outside of said housing for turning said axle to operate said switch.

2. An electrical switch as defined in claim 1 further comprising an annular seal disposed in said aperture of said housing between said axle and the wall of said aperture.

3. An electrical switch as defined in claim 1 further com prising an annular bearing disposed in said aperture of said housing between said axle and the wall of said aperture.

4. An electrical switch as defined in claim 1 further comprising an annular bearing disposed between said axle and the wall of said aperture of said housing and an annular seal disposed in said aperture between said axle and the wall of said aperture, said seal being outwardly disposed in said aperture relative to said bearing.

5. An electrical switch as defined in claim I wherein said housing has a groove in an end wall thereof with said aperture in said housing being communicated with said groove and wherein said external actuator lever is disposed in said groove and extends from an end thereof whereby a plurality of said switches may be disposed in end to end relationship without causing interference with the movement of any of said external actuator levers thereof.

6. An electrical switch as defined in claim 5 wherein said housing is cylindrical and said aperture extends along the axis thereof and wherein said groove and said external actuator lever extends substantially radially with respect thereto.

7. An elecuical switch as defined in claim I wherein said aperture is defined by an annular reentrant section of said housing and wherein a pair of said sets of reed switch contacts are disposed therein one on each side of said reentrant section and wherein a pair of said magnets are supported by said spring means, said magnets being disposed one on each side of said reentrant section of said housing with each being attached to said spring means by a separate one of a pair of arms which normally abut opposite sides of said reentrant section to define the normal position of said magnets in said housing.

8. An electrical switch as defined in claim 7 wherein said spring means comprise a pair of circular springs each being secured to said housing and each having a separate one of said arms secured thereto.

9. An electrical switch as defined in claim 7 wherein said spring means comprises a leaf spring of U-shaped configuration having a base secured to the wall of said housing and having legs which extend towards opposite sides of said reentrant section of said housing.

* l I l

Claims

1. An electrical switch comprising: a housing defining a chamber and having an aperture in one wall which communicates with said chamber, at least one set of reed switch contacts disposed in said housing and having electrical conductors extending therefrom to the exterior surface of said housing, said contacts being of the form which may be caused to open and close by movement of a magnet in the vicinity thereof, spring means disposed within said chamber of said housing and having a fixed portion and a movable portion, a magnet secured to said movable portion of said spring means for movement between a normal position and a second position to operate said reed switch contacts, an axle extending through said aperture of said housing, and being movable angularly with respect thereto, an inner actuator lever extending radially from said axle within said chamber of said housing and having means bearing against said spring means for flexing said spring upon angular movement of said axle to force said magnet from said normal position to said second position thereof, and an external actuator lever extending radially from said axle outside of said housing for turning said axle to operate said switch.

3. An electrical switch as defined in claim 1 further comprising an annular bearing disposed in said aperture of said housing between said axle and the wall of said aperture.

5. An electrical switch as defined in claim 1 wherein said housing has a groove in an end wall thereof with said aperture in said housing being communicated with said groove and wherein said external actuator lever is disposed in said groove and extends from an end thereof whereby a plurality of said switches may be disposed in end to end relationshIp without causing interference with the movement of any of said external actuator levers thereof.

7. An electrical switch as defined in claim 1 wherein said aperture is defined by an annular reentrant section of said housing and wherein a pair of said sets of reed switch contacts are disposed therein one on each side of said reentrant section and wherein a pair of said magnets are supported by said spring means, said magnets being disposed one on each side of said reentrant section of said housing with each being attached to said spring means by a separate one of a pair of arms which normally abut opposite sides of said reentrant section to define the normal position of said magnets in said housing.