CA1154808A

CA1154808A - Switch actuator apparatus

Info

Publication number: CA1154808A
Application number: CA000383798A
Authority: CA
Inventors: Edward V. Leskovec; Richard A. Schwehr
Original assignee: Towmotor Corp
Current assignee: Caterpillar Industrial Inc
Priority date: 1980-12-19
Filing date: 1981-08-13
Publication date: 1983-10-04
Also published as: WO1982002173A1; JPS57501952A; IT1142111B; IT8125645A0; EP0067155A4; EP0067155A1

Abstract

Switch Actuator Apparatus Abstract This invention relates to an apparatus for actuating an electrical switch which eliminates the problems of over stressing and inadvertent cyclical actuation of the switch and flexing of electrical connecting wires. The apparatus has an actuator spring movable in response to a load applied to a seat assembly for applying an actuating force to the switch of a magnitude less than the load applied to the seat assembly and a bracket for limiting the magnitude of force applied to the switch to a preselected maximum value. The apparatus eliminates premature switch failure, inadvertent cyclical switch actuation and electrical wire breakage. The actuating apparatus is particularly useful on a vehicle such as a lift truck.

Description

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Description Switch Actuator Apparatus Technical Field This invention relates to an apparatus for actuating a switch and more particularly to an apparatus for controllably actuating a switch in response to a seat assembly being moved to a preselected elevational position relative to a seat support frame of a vehicle.

Background Art Apparatuses for actua'ting a switch in response to elevational movement of at least a portion of a seat assembly of a vehicle such as a lift truck are well known in the art. Examples of such systems are shown in U.S. Patent 2,708,005 to Gazzo issued May 10, 1955, U.S. Patent 3,437,993 to Recio et al issued April 8, 1969, U.S. Patent 3,500,946 to Boyajian issued March 17, 1970; U.S. Patent 3,703,618 to Lewis issued November 21, 1972; U.S, Patent 3,70~,352 to Fontaine issued November 28, 1972, U.S. Patent 4,075,443 to Fatur issued February 21, 1978, and German Patent 1,048,784 issued January 15, 1959.
Such apparatuses are often disposed between the seat assembly and the switch for actuating the switch in response to movement of the seat assernbly toward the switch due to the weight of a vehicle operator being seated thereon and for deactivating the switch in response to movement of the seat assembly away from the switch due to the weight of the vehicle operator being removed therefrom.

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Typically such switches are operatively connected to a vehicle system for establishing an on or off condition of the system, as determined by an occupied or unoccupied vehicle seat asserably, and -5 permitting or preventing travel of the vehicle.
It has been found that during operation of the vehicle over rought terrain prior switch actuating apparatuses are often too sensitive to seat assembly movement which causes cyclical and unclesirable aetuation of the switch between the actuated and unactuated positions which results in turning on and off the vehicle system.
Such prior actuating apparatuses do not have provisions for limiting the maximum amount of actuating force applied to the switch. Since the weight of the operator under dynamic conditions applies a variable force to the seat assembly of a substantial magnitude and the force applied to the switch is proportional to the force on the seat, a condition rnay be developed when the switch actuating force is beyond the structural limits of the switch. This exeessive force can eause premature failure of the switch which will result in down time of the vehicle.
Often the switch is mounted on the seat assembly for elevational movement with or in response to elevational movement of the seat assembly. When this movement is appreciable, substantial flexing of electrical wires connecting the switch to the vehiele system is observed. This flexing frequently causes breakage of the wires which causes vehicle downtime.
Also, since the switch is mounted on the seat assembly removal of the seat assembly from the vehicle or movement of the seat assembly for operator comfort adjustrnent in a horizontal clirection relative to a seat support surface causes substantial flexing, stretching .

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and bending of the wires. Also, removal of the seat assembly frequently re~uires disconnection or xemoval o~ the switch. In addltion, such systems do not include a provision whereln ease of adjusbment o~ the actuating apparatus can be made for establishing the minimum weight on the seat at whlch switch actuation is achleved, The present invention is directed to overcoming one or more of the pxoblems as set forth 10 above.
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D'i'sclosur'e of the Inv~ention In one aspect of the present invention an apparatus for controllably actuating a switch mounted on a support frame is provided. The actuating apparatus is operatively associated with a vehicle seat and the switch for applying an actuating force to the switch of a smaller magnitude than a $orce applied to ' the seat and limits the force applied to the switch to a preselected maximum value which is less than the force applied to the seat.

B~rief Descr,lption of the Drawings Fig. 1 is a diagrammatiç front elevational view of the seat assembl~ and one embodiment of an actuatin~
apparatus of the present invention with portions thereof broken out and ln section;
Fig. 2 is a diagxa~,matic side elevational view of an alternate embodiment o.~ the seat assembly and actuatin~ appa,ratus of the present invention with portions thereof broken out and in section; and Fig. 3 is a dia~rammatic top elevational view o~ the ac~uating apparatus taken along the line III-III
of FIg. 2~

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seSt Mode for Carrying Out the Invention Referring to -the preferred embodiment of Fig.
1, a seat assembly 10, for a vehicle such as a lift truck (not shown) is pivo-tally attached to a support frarne 12, which may be the frame of the vehicle. The seat assembly 10 includes a seat 14 having a base 16 and a connecting frarne 18. The seat 14 is mounted on the connecting frame 18 and the connecting frame is pivotly secured to the support frame 12. More specifically, the base 16 of the seat 14 is mounted on and rig;dly secured to a guide rail assembly 20 in any suitable manner and the guide rail assembly is moun-ted on the connecting frame 18 and securecl thereto by threaded fasteners 22. The guide rail assembly 20 is of a construction well ~nown in the art and permits selected guided movement of the seat in a horizontal plane parallel to the connecting frame 18 so as to provide comfortable seating for a vehicle operator.
The connecting frame 18 has a first and second 20 end portion 24,26. The first end portion 2~ is pivotly secured to the support frame by a hinge assembly 28 having a pivot pin 30. The connecting frame 18 of the seat assembly 10 is elevationally movable relative to the support frarne 12 as it pivots about pin 30.
A resilient member 32, of preferably rubber material, but may include coil or leaf springs, is disposed between a lower surface 34 of the connecting frame 18 and an upper surface 36 of the support frame 12 at a location spaced from the pivot pin 30. More specifically, the resilient member is affixed to the upper surface 36 of the support frame, in any suitable manner, so as to be in contacting engagement with the lower surface 34 of the connecting frame 18 at a location between the first and second end portions 35 24,26. It is to be noted that the resilient member 32 ~548 maintains a ~ap or space 38 between the upper and lower surfaees 36,34 when the seat is unoccupied. The placement of a load on the seat 14 will eause compression of the resilient member 32 resulting in a reduetion of the spaee or gap 38.
An actuator apparatus 40 is operatively associated with the seat assembly 10 and a switch 42.
The actuator apparatus 40 includes an aetuator spring 44 which has a first and seeond end portion 46,48. The actuator spring 44 is preferably a leaf spring 50, however, other types of springs sueh as eoil or torsion would be suitable substitutes. The seeond end portion 48 of the leaf spring 50 is seeurely attaehed to the eonneeting frame 18, at a location on the conneeting frame spaced from the pivot pin 30, by a threaded fastener 52 and the first end portion 46 of the leaf spring 50 is free from eonneetion with the eonneeting frame 18. The seeond end pcrtion 48 of the leaf spring 50 is preferably eonneeted to the seeond encl portion 26 of the eonneeting frame 18 and the first end portion 46 extends to terminate in an areuate shape at a loeation spaeed further away from the pivot pin 30 than the conneetion of the springs seeond end portion 48 and beyond the eonneeting frame~'s seeond end portion 26.
An adjustment serew 54 is threadabIy connected to the second end portion 26 of the conneeting frame 18 and threadably extensible relative to the eonneeting frame 18. The serew!54 is contaetable with the spring 50 for selectively determining the elevational position of the first end portion 46 of the spring 50 relative to the eonnecting frame and the switeh 42.
The switch 42 is connectecl to the support frame 12 by a bracket 56. Preferably the bracket is "L" shaped and constructed of a resilient material sueh as spring steel. One end portion 58 of the braeket 56 ' , . .

? ~3 is connected to the support frame 12 in any suitable manner and the other end portion 60 iS connected to the switch 42 such as by fasteners 62~ Specifically, the resilient bracket 56, suspends and positions the switch 42 directly beneath the first end portion 46 of the actuator spring 44.
The switch 42 has a plunger 64 which is movable in response to an external force applied thereto for placing the switch in one of an open and closed position. The switch 42 is also movable from one of said open and closed positions to the other of the open and closed positions in response to the force being removed therefrom. Such switch construction is well known in the art and will not be discussed in further detail. A plurality of electrical wire leads 66 are connected at one end to the switch 42. The other end of the leads 66 are connected to an electrical vehicle system (not shown)~ The electrical vehicle system is operative in response to the switch being in one of the open and closed positions and inoperative in response to the switch being in the other of the open and closed positions.
Referring to the alternate embodiment of Fig.

2, a seat assembly 110, is affixed to a support frame 112, which may be the frame of a vehicle. The seat assembly 110 includes a seat 114 having a base 116, a cushion 117 and cushion suspension springs 118. Such a construction is well known in the art and will not be discussed in any greater detail. The base 116 of seat 114 is mounted on and rigidly secured to a guide rail assembly 120 and the guide rail assembly 120 is mounted on and rigidly secured to the support frame 112. The guide rail assembly 120 is of a construction well known in the art and permits selected guided movement of the . .~

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seat 114 in a horizontal plane parallel to the support frame 112 so as to provide adjustment for comfortable seating by a vehicle operator.
An actuator apparatus 122 is operatively associated with the seat assembly 110 and a switch 124. The actuator apparatus includes an actuator spring 126 which has a first and second end portion -128,130 and a middle portion 132. Preferably, the actuator spring 126 is an elongated arcuate shaped leaf 10 spring 134 having an upper surface 136. The first end portion 128 of the actuator spring 126 is pivotly connected to a pivot pin 133 of a support bracket 140.
The support braclcet is securely fastened to the support frame 112 by fasteners 141. More specifically, the 15 first end portion 128 of the leaf spring 134 has an aperature 142 defined therein which is open in a transverse direction relative to the elongated extension of the leaf spring. The pin 138 is disposed in the aperature 142 and permits pivotal movement of 20 the first, second and middle portions 128,130,132 of the actuator spring 126 about said pin.
Referring to Figs. 2 and 3, the switch 124 is pivotly attached to the bracket 140 by fastener 148 so that a plunger 150 faces the first end portion 128 of 25 the leaf spring 134. The plunger 150 is movable in response to an external force applied thereto for placing the switch 124 in one of an open and closed position and movable from one of the open and closed positions in response to the force being removed therefrom to the other of the open and closed positions. Such switch construction is well known in the art and will not be discussed in further detail.
An adjustrnent screw 152 is screw threadably secured to a vertical end portion 154 of the bracket 140 and passes through the end portion 154 to engage the switch 124.

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Preferably the screw 154 engages a flange 156 which is rigidly secured to the switch 124 by fasteners 158. A tension spring 159 connected between the vertical end portion 154 and the flange 156 biases the switch 124 to pivot about the fastener 148 and maintains the flange 156 in contact with the adjustment screw 152. Therefore adjustrnent of the screw 152 will cause the switch to move toward or away from the first end portion 128 of the actuator spring 126. The brac~et 140 further includes a stop 1600 The stop 160 is elevationally positioned between the actuator spring 126 and the support frame 112, and between the first and second end portions 128,130 of the actuator spring 126. The stop is a substantially rectangular tab 162 which extends from the bracket 140 a preselected distance at a location adjacent the pivot pin 138 transverse to the elongate extension of the leaf spring 134 to pass beneath the leaf spring. The rectangular tab 162 is best located between the pivot pin 138 and the middle portion 132 of the leaf spring 134 and at an elevational location within a horizontal projection of the diameter of the pivot pin 138.
The second end portion 130 of the actuator : .
spring 126 terminates in a curvalinear portion 164.
The curvalinear portion is in slideable tangential contact with an upper surface 166 of the support frame 112.
The middle portion of the actuator spring 126 and specifically the upper surface 136 thereof is in corltinuous contact with at least a portion of the cushion suspension springs 118. Any elevational movement of the cushion suspension springs will result :
in elevational movement of the leaf spring 134.

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- 115'~8~8 A plurality of electrical wire leads 168 are connected at an end of the switch 124. The other end of the leads 168 are connected to an electrical vehicle system. The electrical vehicle system is therefore operative in response to the s~itch being in one of the open and closed positions and inoperative in response to the switch being in the other of the open and closed positions.

Industrial Applicability Referring to the preferred embodiment of Fig.
1, the seat assembly 10 is shown in the unloaded position, i.e. without a vehicle operator seated thereon. In this position the resilient member 32 maintains the gap 38 between the lower surface 34 of the connecting frame 18 and the upper surface 36 of the support frame 12 at a maximum by urging i:he connecting frame 18 about the pivot pin 30 away from the support frame 12. At this position the first end portion 46 of the actuating spring 44 is spaced from contact with the plunger 64 of switch 42 and the switch 42 is in one of the open and closed positions. In this position, the vehicle system is conditioned to prevent the vehicle from travel, for example, by applying a brake, neutralizing a transmission or disabling a prime mover.
When a load is applied to the seat 14 of the seat assembly 10 the load will cause the seat assembly 10 to pivot about pin 30 in a direction toward the support frame 12~ This pivotal motion will cause the connecting frame and more importantly second end portion 26 of the connecting frame 18 to move toward the support frame 12 by compressing the resilient member 32 a variable amount as determir-ed by the load placed upon the seat 14. The actuator spring 44, of the actuator assembly 40, being attached to the .
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connecting frame 18 will move in its entirety with the connecting frarne until the first end portion 46 of the actuator spring 44 contacts and forceably depresses the plunger 64 of the switch for actuating the switch 42 to the o-ther of the open and closed positions. In this position the vehicle system woulcl be conditioned to permit vehicle movement, It is to be noted -that the force applied to the switch is proportional to the load on the seat 14 but substantially less than the load, Further movement of the connecting frame 18 of the seat assembly 10 toward the support frame 12, subsequent to depression of the plunger 64 and actuation of the switch 42 will result in no movement of the first end portion 46 of the actuator spring relative to the switch 42 as the second end portion 48 moves with the connecting frame 18. Both the first end portion 46 of the actuator spring 44 and the resilient bracket 56 supporting the switch 42 will move together slightly when the force applied to the switch 42 by the first end portion 46 of the actuator spring reaches a preselected magnitude which is substantially less than the load applied to the seat assembly. This will prevent excessive loading of the switch and reduce premature failure thereofO
The spring 44 of the actuator assembly 40 also acts to resist cyclical actuation of the switch 42 due to oscillation of the seat assembly and its load caused by the vehicle operating over rough terrain. The actuator spring 44 is adjustable between spaced elevational positions relative to the connecting frame by the adjusting screw 54. This permits the first end portion 46 of the actuator spring to be pos;tioned elevationally relative to the switch 42 to establish a minimum force on the seat 14 at which the plunger 64 is contacted and the switch 42 actuated. This minimum , ,: -, . . .
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--ll--seat force is substantially less than the averageweight of an operator and therefore any slight elevational movement of the connecting frame due to bouncing will not deactivate the switch and prevent the vehicle from travelling.
It is to be noted that the wire leads 66 from the switch 42 to the vehicle system encounter substantially very little movement during operation of the vehicle and with the seat 14 occupied. Thus failure due to wire breakage will be lessened.
Referring to the alternate embodiment of Figs.
2 and 3, the seat assembly 110 and actuating apparatus 122 is shown in an unloaded position in solid lines and in a loaded position in phan-tom lines.
In the unloaded position, i.e. the vehicle operator is not seated thereon, the seat 114 and cushion support spring 118 are at an undeflected elevational position and the first end portion 128 of the actuator spring 126 is spaced from contact with the plunger 150. Therefore, the switch is in one of the open and closed positions and the electrical vehicle system is conditioned to prevent the vehicle from travel such as, for e~ample, by applying a brake, neutralizing a transmission or disabling a prime mover.
When a load is applied to the seat 114 of the seat assembly 110 the weight of the load will cause the cushion suspension springs 118 to deflect toward the support frame 112. The change in the elevational position of the cushion suspension springs 118 ~
result in equivalent elevational movement of the middle portion 132 of the actuator spring 126 of the actuator apparatus 122 since the middle portion 132 and specifically the upper surface 136 is in continuous contact with at least a portion of the seat suspension spring 118. This elevational movement of the middle -:

portion 132 will cause both the first and second end portions 128,130 of the actuator spring 126 to move in a predetermined proportional manner. The second end portion 130 will move elevationally but will also deflect outwardly as the curvalinear portion 164 slides along the surface 166 to a location determined by the load placed on the seat assembly 110. Such a location is shown by phantom lines on Fig. 2. The first end portion 128 will also move, however, in a different manner. Since the first end portion 128 is piv~tly connected to pivot pin 138 deflection of the actuator spring toward the support frame 112 will result in pivotal movement of the first end portion 128 about the pivot pin 138 toward the switch 124. This movement will result in forceable engagement of the plunger 150 and translation thereof. It is to be noted that this construction eliminates inadvertent cyclical actuation of the switch by isolating the switch 124 from direct contact with the seat assemblyO Thus, the switch will be actuated to the other of the open and closed positions at which the electrical vehicle system is conditioned to permit vehicle travel such as by releasing the brake, engaging the transmission or enabling the prime mover.
The stop 160 has been provided to limit the amount of pivotal movement of the first end portion 128 of the actuator spring 126. Since the force applied to the plunger 150 and ultimately the switch 124 by the first end portion 128 of the actuator assembly is less than the weight of the load on the seat assembly 110 but proportional thereto it is necessary to establish a maximum force limit. This is achieved by placing a limit on the permissible amount of pivotal movement the first end portion 128. When the load on the seat reaches a preselected maximum magnitude, the deflection , . ., , : , . ........................ : ~:
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~54 of the cushion suspension spring 118 and the actuator spring 122 will force the actuator spring closely adjacent the first end portion 128 of the actuator spring to pivot about pin 138 until it engages the stop 160. Further deflection of the actuator spring 122 due to loads in excess of the preselected maximum magnitude will not result in additional pivotal motion of the first end portion 128 on either side of the pin 138 and therefore the force on the switch will be limited.
The minirnum force required to actuate the switch 124 by depressing the plunger 150 is deterrnined by adjusting the position of the switch 124 relative to the first end portion 128 of the actuator spring 126.
This is achieved by rotating the adjusting screw 152 which pivotly moves the switch 124 about fastener 143.
It is to be noted that the switch 124 does not move under normal operation and therefore the elctrical wire leads 168 are not subjected to flexing and the like.
Therefore, the embodiments herein described eliminate over stressing of the electrical switch and premature switch failure, inadvertent cyclical switch actuation, and electrical wire brealcage.
Other aspects, objects and advantages of the invention can be obtained from a study of the drawings, disclosure and appended claims.

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Claims

1. An apparatus for controllably actuating a switch mounted on a support frame in response to a load being applied to a seat assembly comprising:
actuator means operatively associated with said seat assembly and said switch for sensing elevational movement of said seat assembly relative to said support frame and applying an actuating force to said switch of a magnitude less than the load applied to said seat assembly, and for limiting the magnitude of force applied to said switch to a preselected maximum value which is substantially less than the load being applied to said seat assembly;
said actuator means includes an actuator spring having a first end portion and a second end portion, said first end portion being contactable with said switch and forceably engageable therewith in response to movement of the seat assembly towards said support frame.

2. The apparatus as set forth in claim 1 wherein said actuator spring is a leaf spring.

3. The apparatus as set forth in claim 1 including means for adjusting the relative position of said actuator means and said switch and establishing a minimum seat assembly load at which said switch is actuated.

4. The apparatus as set forth in claim 3 wherein said adjusting means includes an adjustment screw engageable with one of said switch and said actuator spring and selectively positionable to move one of said switch and actuator spring relative to the other of said switch and acuator spring.

5. The apparatus as set forth in claim 2 wherein the second end portion of said actuator spring is connected to said seat assembly.

6. The apparatus as set forth in claim 5 wherein said seat assembly includes a seat having a base and a connecting frame, said base being attached to said connecting frame, said connecting frame being pivotly connected to said support frame by a pivot pin, and, resilient means disposed between said connecting frame and said support frame for urging said seat assembly away from said support frame about said pivot pin.

7. The apparatus as set forth in claim 6 wherein the second end portion of said actuator spring is rigidly secured to said connecting frame at a location spaced from said pivot pin and movable therewith; and said first end portion of the actuator spring being movable relative to said connecting frame, subsequent to contacting engagement with said switch and actuation thereof, a preselected amount.

8. The apparatus as set forth in claim 1 wherein said actuation means includes a resilient bracket connecting said switch to said support frame.

9. The apparatus as set forth in claim 6 wherein said connecting frame has a first and second end portion, and said resilient means is a rubber pad affixed to said support frame and in engagement with said connecting frame at a location between the first and second end portion.

10. The apparatus as set forth in claim 2 wherein said actuator spring has a middle portion slidably engaged with said seat assembly, and said second end portion is slidably engaged with said support frame.

11. The apparatus as set forth in claim 10 wherein said actuator means includes a bracket mounted on said support frame and said switch mounted on said bracket, said actuator spring being pivotly connected between the first and second end portions of said actuator spring to said bracket by a pivot pin.

12. The apparatus as set forth in claim 11 wherein said seat assembly includes a seat, a cushion and a cushion suspension spring resiliently supporting said cushion, said middle portion of said actuator spring being in continuous contact with said cushion suspension spring and deflectably movable in response to elevational deflection of said cushion suspension spring.

13. The apparatus as set forth in claim 1 wherein said actuator means includes a stop operatively assocated with said actuator spring and contactable therewith in response to a preselected amount of elevational movement of at least a portion of said seat assembly toward said support frame.

14. The apparatus as set forth in claim 11 wherein said actuator means includes a stop connected to said bracket and extending therefrom to a location between said actuator spring and said support frame and between said first and second end portions of said actuator spring, said stop being engageable by said actuator spring in response to a preselected amount of movement of said actuator spring toward said support frame.