Abstract:
A vehicle seat safety system using an electric seat mounted switch sensing the operator&#39;s presence in the seat. The electric switch includes an upwardly extending actuator and an actuator plate is superimposed over the switch actuator which is deflected downwardly by the vehicle operator&#39;s weight. The actuator plate is formed of an upwardly bowed resilient material and includes lateral extensions whereby the safety switch will sense the operator&#39;s weight even though the operator&#39;s center of gravity is significantly laterally shifted. Additionally, the switch is received within a uniquely configured opening whereby the switch may be easily replaced, or installed, from the lower side of the seat without disassembly of the upper seat components.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to vehicle safety systems sensing the operator&#39;s weight upon the vehicle seat and is characterized by its simplicity of construction, ease of assembly and disassembly, and ability to sense a shifting of the operator&#39;s weight upon the seat. 
     2. Description of the Related Art 
     A number of vehicle safety systems utilize an electric switch which senses the operator&#39;s presence upon the vehicle seat whereby desired vehicle functions can be rendered inoperative if the operator is not seated. 
     Such vehicle safety systems may include a switch mounted in the central region of the seat lower panel, or a switch sensing the position of the seat support structure, and includes an upwardly extending or moving switch actuator which is depressed by the operator&#39;s weight and is released when the operator&#39;s weight is removed from the actuator. One of the problems encountered with this type of switch controlled vehicle safety systems arises from the fact that if the operator&#39;s weight laterally shifts on the seat, the electric switch may operate even though the operator is located on the seat and desires normal vehicle operation. Such inadvertent safety switch operation due to the operator&#39;s weight shifting on the seat is troublesome, inconvenient and may raise safety concerns. 
     Another problem that arises with vehicle seat safety systems utilizing electric switches mounted in the lower panel of a vehicle seat results from difficulty in assembling the electric switch into the seat, or removing the electric switch for maintenance and replacement purposes. Vehicle seats usually include foam cushions or covers integrally attached to the seat pan and back, and it is difficult to directly incorporate the electric switch into the seat structure in such a manner as to permit easy switch installation and removal. Accordingly, in many vehicle safety systems utilizing electric switches operated by the operator weight, the switch is located exteriorly of the seat necessitating a vertically movable seat support, which may not be desirable. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a vehicle seat safety system for use with cushioned vehicle seats which employs an electric switch mounted within the seat bottom or lower panel, and wherein the electric switch will sense the operator&#39;s weight even though such weight is laterally displaced upon the seat. 
     Another object of the invention is to provide a vehicle seat safety system wherein an electric switch is directly mounted in the seat lower panel and may be inserted into the seat panel, and removed therefrom, from the lower side of the seat panel without necessitating special tools or disassembly of the seat, and yet the electric switch will be positively maintained in the desired operative position. 
     SUMMARY OF THE INVENTION 
     The vehicle safety system in accord with the invention is associated with the lower panel of the seat pan and may be utilized with vehicle seats of various configurations with or without back rests. 
     The seat bottom consists of a lower panel, usually stamped of metal, and a foam cushion is supported by the lower seat panel. The seat lower panel includes upper and lower sides, as well as a central region, lateral sides and a forward and rear region. 
     An opening is defined in the seat lower panel central region equally spaced between the panel lower sides, and an electric switch having an upwardly extending actuator located upon the switch is mounted within the panel opening. Vertical movement of the actuator operates the switch. 
     An actuator plate is superimposed over a significant portion of the upper side of the seat lower panel central region, and over the switch actuator. Preferably, the actuator plate is formed of a resilient material, such as spring steel, and is bowed upwardly so that the portion superimposed over the switch actuator is normally out of engagement with the actuator, and the actuator plate includes a forward edge disposed toward the lower seat panel forward region, and the actuator plate also includes a rear edge disposed toward the seat panel rear region. The rear edge of the actuator plate is formed with a pair of hinged projections which are received within openings defined in the seat lower panel forming a hinge for the actuator plate and maintaining the actuator plate in its desired position over the electric switch and its actuator. 
     The actuator plate is located below the flexible seat cushion wherein weight on the seat cushion depresses the actuator plate operating the switch actuator. In order that the electric switch will always sense the presence of the operator&#39;s weight, extensions are defined on the lateral sides of the actuator plate extending toward the seat lower panel lateral sides. These actuator plate extensions render the actuator plate sensitive to the operator&#39;s lateral movement upon the seat permitting the switch to sense the operator&#39;s presence upon the seat even though the operator&#39;s weight significantly shifts laterally on the seat for whatever reason. 
     The opening for receiving the electric switch located within the central region of the seat lower panel is of a general “keyhole” configuration, i.e. includes a larger portion intersecting an elongated smaller portion. The opening larger portion is of such dimension in relationship to the dimension of the electric switch body to permit the electric switch body to be inserted through the opening large portion, actuator first. The switch body includes a smaller dimension and a ledge or shoulder is located between the switch body larger and smaller dimensions. Upon inserting the switch body through the large dimension, which also accommodates the shoulders, the switch body may be laterally moved into the opening smaller dimension toward the lower panel rear region with the switch body shoulders being located above the lower panel opening. The smaller dimension portion of the opening permits the switch body shoulders to overlie the edges of the smaller dimension opening preventing the switch body from being pushed through the lower panel, and small stop shoulders defined in the neck of the opening small dimension cooperate with the configuration of the switch body to prevent lateral movement of the switch body toward the opening large dimension during vehicle use. 
     Accordingly, the switch may be quickly installed within the lower panel opening by aligning the switch body and its shoulders with the opening larger portion and pushing the switch therethrough, laterally displacing the switch body over the opening smaller dimension, and lowering the switch into the opening smaller dimension permitting the switch body shoulders to rest upon the upper surface of the seat lower panel. Removal of the switch from the seat lower panel requires the reverse procedure of that previously described. 
     Excessive pressure upon the switch actuator is prevented by bosses defined in the seat lower panel extending upwardly from the seat panel upper side which will be engaged by the switch actuator plate to prevent excessive depression of the actuator plate. 
     The vehicle seat safety system of the invention provides an economical manner for mounting an electric switch directly within a seat lower panel, permitting the switch to be installed, or removed, from the seat lower panel quickly and without harm or disassembly to the cushioned portion of the seat. Further, by the utilization of the actuator plate lateral extensions, the electric switch will sense the operator&#39;s weight even though such weight has been laterally displaced on the seat due to turning, the operator leaning laterally, or otherwise shifting his weight. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein: 
     FIG. 1 is a perspective view of a seat pan utilizing the invention, such seat employing a back rest, and the seat cushion being omitted for clarity of illustration, 
     FIG. 2 is an elevational sectional view of the seat pan of FIG. 1 as taken along Section  2 — 2  thereof, 
     FIG. 3 is a detail plan view of the upper side of the seat lower panel, the electric switch being removed from the lower panel opening for purpose of better illustrating the configuration of the opening, 
     FIG. 4 is a plan elevational view of the electric switch actuator plate, per se, and 
     FIG. 5 is a detail elevational view of the central region of the seat lower panel with the electric switch in place, and the actuator plate being omitted for purpose of illustration as taken along Section  5 — 5  of FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1, a typical seat pan is shown at  10  of the type that is commonly used with tractors, garden tractors, fork lift trucks and other agricultural or industrial equipment. The seat pan may be pressed of steel, which is the usual case, or could be molded of a rigid synthetic material. In FIG. 1, the illustrated seat pan  10  includes a back panel  12  and a bottom or lower panel  14 . A cushion, usually of compressible foam, will be placed upon the back and bottom panels in the known manner to provide a comfortable seat, but for purpose of illustration of this cushion in FIG. 1 is omitted. 
     The lower panel  14  includes an upper side  16 , a lower side  18 , a central region  20 , lateral sides  22 , and a forward region  24  and a rear region  26  located adjacent the back panel  12 . 
     At its central region  20 , an upwardly extending circular boss  28  is defined in the lower panel  14 , FIG. 5, and an opening  30  is centrally defined within the boss  28  having a configuration as will be appreciated from FIG.  3 . 
     The opening  30  is of a “keyhole” configuration in that the opening includes a large rectangular portion  32  intersected by a smaller dimensioned portion  34  which includes a reduced dimension neck  36  whereby shoulders  38  are defined between the neck  36  and the small portion  34 . 
     Upon each lateral side of the opening  30 , a pair of stop protrusions  40  are defined on the boss  28  as best illustrated in FIG.  5 . It will be noted that the protrusions  40  extend upwardly from the seat panel upper side  16 . 
     The electric switch which controls the vehicle component which provides the seat safety function is generally indicated at  42 . The switch  42  includes a switch body  44  of a general rectangular configuration which has an upper maximum dimension  46  defined by flanges  47  and a reduced or minimum dimension  48 , FIG. 5, which is slightly less than the width of the opening small portion  34 , but greater than the width of the opening neck  36 . A shoulder  50  is defined between the flanges  47  and the minimum switch body dimension  48  as will be appreciated from FIG.  5 . 
     From the above description of the relative dimensions of the opening  30  and the switch body  44 , it will be appreciated that the switch  42  may be inserted into the opening  30  from the lower side  18  of the lower panel  14 . This insertion of the switch into the opening  30  is accomplished by inserting the switch body  44  into the opening large portion  32  with the switch actuator  52  being inserted first. Upon the switch body  44  being fully inserted into the opening portion  32 , the switch body may then be laterally moved over the neck  36  until the switch body is in alignment above the opening small portion  34 . Thereupon, the switch body portion  48  may be pulled downwardly into the opening portion  34  to the position shown in FIGS. 2 and 5. Because the switch body dimension  48  is greater than the opening neck  36 , it is not possible to move the switch body back toward the opening large portion  32  because of the shoulders  38 , and the switch  42  will be positively retained in the proper location within opening  30 . From the above description, it will be appreciated that the switch  42  may be removed from the opening  30  by reversing the above described procedure. Further, it will be appreciated that as the installation of the switch  42  onto the lower panel  14  completely takes place from the lower panel lower side, installation and removal of the switch  42  does not interfere with the seat cushion or superstructure. 
     The switch  42  is operated by an upwardly spring biased actuator generally indicated at  52 . The actuator  52  is operated by an actuator plate  54  having a configuration which will be appreciated from FIGS. 2 and 4. The actuator plate  54  includes a front edge  56  of a paddle-type shape, a rear edge  58 , lateral edges  60  and a central region  62 . As will be appreciated from FIG. 2, the actuator plate  54  bows upwardly away from the panel upper side  16  between the front and rear edges  56  and  58 , respectively. The actuator plate  54  is formed of a high strength resilient material, such as spring steel, or the like, so as to maintain its “relaxed” position as shown in FIG. 2 wherein the central region  62  will be superimposed over the switch actuator  52 . 
     The actuator plate rear edge  58  includes a pair of rearwardly extending hinge tabs  64 , FIG. 4, which extend in the longitudinal direction of the elongated actuator plate, and lateral extensions  66  are defined upon the actuator plate at its central region for a purpose later described, and extensions  66  are also formed on end  56 . 
     A pair of hinge holes  70  extend through the lower panel  14  adjacent the rear region  26  as will be appreciated from FIGS. 1 and 2. The actuator plate hinge tabs  64  are received within the hinge holes  70 , FIG.  1 . 
     When assembling the seat pan  10 , the actuator plate  54  will be assembled to the lower panel upper side  16  by inserting the hinge tabs  64  into the hinge holes  70 . If desired, the switch  42  may be inserted into the opening  30  prior to assembling the actuator plate to the lower panel. However, it will be appreciated that the time at which the switch  42  is inserted into the opening  30  is optional as the switch  42  may be inserted into the opening  30 , or removed therefrom, at any time. 
     After the actuator plate  54  is properly located on the lower panel upper side  16  with its tabs  64  within the hinge holes  70 , the cushion, not shown, may be mounted upon the upper side of the seat pan  10  in the conventional manner, and the spring resiliency of the actuator plate  54  constitutes biasing means sufficient to prevent the cushion from depressing the actuator plate into engagement with the switch actuator  52  so that the relationship shown in FIG. 2 between the actuator plate  54  and the switch  42  exists even though the foam is mounted upon the seat pan. Also, the switch actuator  52  will be biased upwardly by an internal spring. Preferably, the bottom of the cushion, not shown, is recessed directly above the actuator plate  54  in a configuration corresponding to that of the actuator plate, and this recessing of the cushion will insure that no force is applied to the actuator plate until the operator sits on the seat cushion. The recessing of the cushion helps to insure that the cushion does not settle and apply force to the actuator plate when the operator is not in the seat, and this recessing of the seat cushion insures that the switching mechanism will operate in the desired manner. 
     When an operator sits upon the seat cushion, not shown, the operator&#39;s weight will depress the actuator plate  54  downwardly into engagement with the switch actuator  52 , depressing the switch actuator  52  to either open or close switch  42 , depending on the type of switch utilized. In this manner, the switch  42  will control the desired safety function component of the vehicle, for instance, permit the engine to be started, permit a power takeoff to be engaged, or control other functions. 
     Regardless of the weight of the operator, the actuator plate  54  will not be depressed excessively as to possibly damage the switch  42  in that the actuator plate will engage the stop protrusions  40  preventing further depression of the switch actuator and possible damage to the switch. 
     During the operation of a vehicle, it is not uncommon for the operator&#39;s weight upon the seat to laterally shift, such as when turning, traversing a hill, or leaning laterally to obtain better vision. In such instances, the operator is properly seated and the operation of the vehicle must be normal. The presence of the lateral extensions  66  permits enough of the operator&#39;s weight, even when displaced laterally, to be applied to the actuator plate  54  to depress the switch actuator  52  in order to maintain normal vehicle operation. Further, the width of the actuator plate front edge is such as to accommodate this lateral force imposed on the actuator plate, and as the rearmost lateral extensions  66  are substantially in a transverse line with the switch  42 , the hinging of the actuator plate, and the pressure applied to the actuator plate by the extensions  66  insures normal vehicle operation under all safe operating conditions. 
     From the above description, it will be appreciated that the invention permits economical structure to be utilized with a vehicle seat safety system which is dependable in operation, rugged in use, and permits the electric switch to be assembled or removed from the seat without requiring seat disassembly. 
     It is appreciated that various modifications to the inventive concepts may be apparent to those skilled in the art without departing from the spirit and scope of the invention.