AU597598B2

AU597598B2 - Improvements to switch assemblies

Info

Publication number: AU597598B2
Application number: AU64187/86A
Authority: AU
Inventors: Theodore William Reinhold
Original assignee: Bartlem Pty Ltd
Current assignee: Bartlem Pty Ltd
Priority date: 1985-10-17
Filing date: 1985-10-17
Publication date: 1990-06-07
Anticipated expiration: 2006-10-17
Also published as: AU6418786A

Description

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597598 COMMONWEALTH OF AUSTRALIA Patents Act 1952 in a11r1y nent contains the amendments made under Section 49.

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OI 0 o so so O oaa~ ooor co so ir o ra op r o so so r e tr I~rl THE OD ORE WIL rl I P1S1 /J: RE I NHOLD 37 I-IIE a ID C) 1=11 IH: W :E T-j T-1 71- 21-M t t ro Q COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED:- "IMPROVEMENTS TO SWITCH ASSEMBLIES" The following statement is a full description of this invention, including the best method of performing it known to me:t- L 2 THIS INVENTION relates to improvements to switch assemblies particularly to key-actuated switch assemblies suited for use in ligh current applications, such as starter motor switches.

A number of different types of starter switches are available which employ key operated actuating mechanisms.

While these mechanisms are generally suited to applications Tihere the switch is not exposed, they are not particularly suited for use in vehicles such as tractors, ride-on mowers 1o 0 or the like which are often exposed to rain which tends to o° cause water to be forced into the switch to either damage the actuating mechanism or the switching contacts, thereby o rendering the switch inoperable.

0 64 These known switches are generally of a type comprising a key barrel of the displaced pin type, originally designed for something other than the high-current application of o o starting a ride on mower without the advantage of a relay to o" °shunt the majorAy of the current required for starting away from the switch. The contacts of such switches are generally radially engaged against a spring bias. Apart from the i obvious limitation on contact size a'id thus current carrying Ia ~capacity imposed by this constraint, it is particularly difficult to waterproof such a switch from ingress through the key aperture.

Furthermore, the known types of switches particularly when in external applications are often susceptible to

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tampering.

The present invention aims to overcome or alleviate at least some of the above disadvantages by providing an improved switch assembly particularly suitable to starting switch applications in ride-on mowers or the like. The switch of the present invention however may be applied to any application where high current or any other current switching is required. Other objects and advantages of the invention will become hereinafter apparent.

With the foregoing and other objects in view, the invention resides broadly in a key-actuated switch assembly n including a switch housing; 9 electrical terminals associated with said housing; 0A0 conducting means within said housing for opening and closing the circuit between said terminals; biasing means within said housing and arranged to oas normally bias said conducting means towards an open-circuit or inoperative condition; a key-receiving aperture associated with said housing *t, S 20 and having an actuating key adapted to be utilized to render operative said conducting means; and cam ramp means in the housing within the key-receiving aperture and adapted to co-operate with said radial protrusion on the key shank when the key is rotated, and wherein the key-receiving aperture is adapted to receive and

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7: p 1R gq 0-pp p 00O 0 p 8 accommodate the actuating key shank inserted axially therein and to receive and accommodate a radial protrusion provided rigidly on said key shank, and said cam ramp means is so shaped as to cause relative movement between the key and the housing, in the direction axially of the key shank, when the key is rotated, whereby to cause closing of said circuit against the action of said biasing means.

In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate the apparatus of the invention and wherein:- Fig. 1 is an exploded sectional view of the switch and associated key according to the present invention; Fig. 2 is a developed view of the cam employed in the switch; and Figs. 3 and 4 are respective sectional views showing the switch in an inoperative and an 20 operative attitude respectively.

Referring to the drawings and firstly to Fig. i, there is illustrated a switch assembly 10 according to the present invention including a housing 11 having first and second parts 12 and 13 which are arranged to be interconnected and secured together by any suitable means such as by rivets or the like. The first housing part 12 includes a generally *P 4

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I tr~ 0100 4 0i04 rl tubular key receiving portion 14 which is provided with an aperture 15 therein for receiving a key 16. The aperture also includes a longitudinally extending keyway 17 arranged to receive a radially extending pin 18 of the key 16. The aperture 15 leads to a camming surface 19 (more clearly illustrated in developed view in Fig. 2) which is adapted to co-operate with the key pin 18 to guide the pin 18 along a desired path during rotation of the key 16 and thereby cause a desired axial switch actuating movement of the key 16. The tubular portion 14 also includes an enlarged internal bore J :at its end opposite the key aperture 15 which is adapted to ao O I neatly receive a cylindrical plunger 21 therein. The plunger o 21 is provided with a central locating pin 22 for engagement 4444 with a central aperture formed in a contact bar 23 which as M~oo illustrated is deformed adjacent its opposite ends to define a pair of contact points 24.

oe The other or second housing part 13 is provided with a 26 for engagement by a respective contact point 24 of the contact bar 23. The housing part 13 is also provided with a 4444 recess 27 for sealing of biasing spring 28 which locates on a seat about the locating pin 22 of the plunger 21 so that when the housing parts are assembled, the compression spring 28 normally bias the plunger 21 so that when the housing parts are assembled, the compression spring 28 normally bias the plunger 21 and contact bar 23 to an inoperative attitude. As @u S 7OF# 6 shown in Fig. 2, the cam surface 19 includes a first arcuate lead in portion 29 adjacent the keyway 17 which leads the pin 18 of the key 16 to a detente recess 30 where the switch is positively set in an inoperative attitude. The cam surface 19 also includes a ramp portion 31 which extends from the recess 30 and which is arranged to cause the shank of the key 16 to move axially inwardly when rotated as the key pin 18 rides upwardly along the ramp portion 31. However the configuration of the switch components and the camp ramp portion 31 prevents the pin 18 from moving beyond the ramp 9 Get o, portion 31 onto the flat portion 32 of the cam surface 19.

or Referring now to Figs. 3 and 4, there is illustrated the switch assembly 10 in an inoperative and operative attitude 094: S°respectively. In the inoperative attitude the key 16 is Po0 inserted into the key aperture 15 with the pin 18 aligned with the keyway 17 and so that the end of the key 16 abuts o the plunger 21. Rotation of the key 16 will cause the pin 18 0 00 to ride up over the arcuate portion 29 of the cam surface 19 o° 2 against the bias of the spring 28 and along the cam surface 19 until the pin 18 locates or drops into the recess 30 to be held in the recess 30 under the influence of the spring 28.

it.. ihth n o h This position is illustrated in Fig. 3 with the end of the key 16 in contact with the plunger 21 but with the contact bar 23 spaced from the contact surfaces 26. Axial movement of the key shank during movement of the pin 18 along the camming surface 19 to the recess 30 is not sufficient to 7 cause contact between the bar 23 and surfaces 26 to be made.

When the switch 10 is required to be actuated, the key 16 is further rotated so that the pin 18 moves along the ramp 31, thus causing axial inward motion of the key 16 and corresponding inward motion of the plunger 21 and contact bar 23 against the bias of the spring 28. Suitable guide means (not shown) are provided to prevent rotational displacement of the bar 23 in it movement towards or away from the contact points 26. This motion continues until the contact points 24 engage the contact surface 26 to close the circuit between 0oa oK0 the terminals 25. Thus in this attitude (shown in Fig. 4) current may be applied through the switch 10 say to a starter 0 0 0° motor. During this period the switch 16 must be held against 0000 o o rotation to maintain the contact.

If the switch 16 is released, the force of the spring 28 will cause the pin 18 to ride down along the ramp 31 to the o recess 30 and thus effect retraction of the plunger and 0 0 00 contact bar 23 so that the circuit is broken. This therefore o:0 ensures positive return of the switch 10 to an inoperative attitude. The plunger 21 whilst acting to support the qp contact bar 23 also ensures that the key aperture 15 is £050 isolated from the electrical contacts and therefore the switch 10 is substantially weatherproof when in an inoperative attitude.

A switch assembly as described will be found to achieve most effectively the objects for which the invention has been 8 devised. The construction is simple, with no elaborate components and not requiring the use of a solenoid. Normal types of special individual keys are not required, and the design can cater for heavy currents such as over a hundred amps for an hour. When the key is taken out of the housing, small children cannot actuate the switch to start a motor, such as that of a ride-on mower. The plunger in the housing acts to seal the interior against entry of water, particularly when the key has been removed. In practice, the key is put in upside down, then turned through 180 degrees to *to oo the detente or "run" position, whereafter a further turn clockwise of about 20 degrees will effect cam ramp action to close the circuit, such as for a starter motor.

5550 oo Many different configurations of camming surfaces may be

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used to achieve the on-off switching function of the switch.

Furthermore the key pin 18 may be either formed integrally ooi S54lry h with the key shank or separately therefrom. Similarly the 5 key pin 18 may be of any suitable configuration to follow the cam surface 19, provided that it forms a radial protrusion t 20 from the. key shank. All such variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as defined by the appended claims.

Claims

1. A key-actuated switch assembly including a switch housing; electrical terminals associated with said housing; conducting means within said housing for opening and closing the circuit between said terminals; biasing means within said housing and arranged to normally bias said conducting means towards an open-circuit @0 or inoperative condition; o o 0 0 0 a key-receiving aperture associated with said housing o and having an actuating key adapted to be utilized to render operative said conducting means; and cam ramp means in the housing within the key-receiving aperture and adapted to co-operate, when the key i3 rotated, oo. 15 with a radial protrusion provided rigidly on said key shank, o*o oo.° and wherein c the key-receiving aperture is adapted to receive and accommodate the actuating key shank inserted axially therein and to receive and accommodate said radial protrusion, and 0 *0O* 20 said cam ramp means is so shaped as to cause relative movement between the key and the housing, in the direction axially of the key shank, when the key is rotated, whereby to cause closing of said circuit against the action of said biasing means. 44 ado a 04 4o 4 4, 0 i *at* a 0 4 4 4 a a 00 4444 00 4 44 4444 4444 44 4 4 44 4 4* a

2. A key-actuated switch assembly according to Claim i, wherein said cam ramp means includes a detente recess adjacent the ramp of said cam ramp means, said detente recess being adapted to co-operate with said radial protrusion on the key shank to retain the key in said first and inoperative position and attitude, subsequent rotation of the key causing said radial protrusion to coact with said cam ramp means to move the key to said second and operative position and attitude. .0

3. A key-actuated switch assembly according to any one of the preceding claims, wherein the biasing means comprises a compression spring extending linearly within the housing between a first seat on a movable contact bar constituting said conducting means and a second seat on a mounting base .5 having said electrical terminals thereon. J11

4. A key-actuated switch assembly according to any one of the preceding claims, wherein the housing comprises first and second housing parts adapted to be releasably interconnected and defining a chamber therebetween, said first housing part being outermost in use and having the conducting means and key-receiving aperture therein, the second housing part being fitted with said electrical terminals, said biasing means being located in said chamber. 11 A key-actuated switch assembly according to Claim 4, wherein said biasing compression spring has its axis co- extensive with the key shank axis, the adjacent ends thereof being separated by said contact bar against the end of the spring and a guide and sealing plunger mounted slidably and closely in a corresponding bore of the first housing part to connect between said contact bar and the inner end of the actuating key, said sealing plunger also being coaxial with o the compression spring and the key shank axis. o 99 9 0 a s. 10 6. A key-actuated switch assembly substantially as hereinbefore described with reference to accompanying o 04 osOa° drawings. DATED THIS First DAY OF December, 1989. Sooa a 0 0 06 0 THEODORE WILLIAM REINHOLD 15 BY o 0 4 PIZZEY COMPANY PATENT ATTORNEYS 60c6