Abstract:
An outrigger to prevent a moving vehicle from overturning includes an arm that normally stays in a retracted, stored position that allows the vehicle freedom to travel, but then automatically extends to brace the vehicle in response to tilting to a predetermined limit. The arm has a pivotal or linear motion driven by virtue of its own weight or by spring force. A releasable latch holding the arm in the stored position automatically releases the arm in response to a mechanical or electrical tilt sensor that detects that the vehicle has tilted to the limit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention generally pertains to the prevention of a vehicle from overturning and more specifically to an outrigger for a vehicle. 
     2. Description of Related Art 
     Outriggers are often used to stabilize or prevent a parked vehicle from tilting. They are commonly found on service or construction vehicles that become generally top-heavy due to a crane mast or an extension ladder extending from the vehicle. When the vehicle parks to perform its service operation, the outrigger is extended sideways from the stationary vehicle and downward against the ground to widen the vehicle&#39;s base. When the service operation is complete, the outrigger is returned to a stored position, so as not to impede the vehicle&#39;s travel. Outriggers are usually moved manually or hydraulically between their stored and extended positions. Although such outriggers work well for parked vehicles, they are ineffective in preventing traveling vehicles from overturning. 
     Traveling vehicles can be caused to tip over for several reasons. For example, if the wheels on only the right or left side of the vehicle drive over an obstacle or void in the road or driving surface, that disruption could overturn the vehicle. An inclined driving surface would have a similar tipping effect upon a vehicle traversing the incline. Quick turns can also create a centrifugal force sufficient to overturn a vehicle. In the case of a forklift truck, raising a heavy load high overhead can make the forklift top-heavy and prone to tipping. To prevent a moving vehicle from tipping over, some vehicles include a ballast that moves automatically to shift the vehicle&#39;s center of gravity to counterbalance the tipping. Various types of moveable ballasts are disclosed in U. S. Pat. Nos. 2,916,172; 3,497,095; 4,221,530; and 4,502,709. Unfortunately, the weight of a moveable ballast has to be significant in comparison to the weight of the vehicle to be really effective. And a ballast of substantial weight can add unnecessary bulk and cost to a vehicle. 
     Minimizing bulk is especially important for vehicles, such as forklift trucks that need to maneuver within narrow aisles and between various obstacles that typically clutter shipping and receiving areas of a building. Shopping carts are another example of a vehicle that needs to travel within narrow aisles, and they tend to be top heavy and prone to tipping, especially when a child is in the cart. Lawn tractors often need to maneuver among trees and other obstacles, and are more prone to tipping when traversing inclined terrain. These are just a few examples of vehicles that could benefit from a compact anti-tipping device. 
     SUMMARY OF THE INVENTION 
     In order to provide a traveling vehicle with protection against overturning without adding unnecessary weight or bulk to the vehicle, an outrigger is provided that includes an engaging member that normally stays in a retracted, stored position, but then automatically extends to brace the vehicle in response to the vehicle tipping to a predetermined limit. 
     In some embodiments, a inclination sensor and a latch are combined into a single element that normally holds a spring-loaded arm in its retracted, stored position and then automatically releases the arm upon sensing the vehicle tipping to the predetermined limit. 
     In some embodiments a spring-loaded arm of an outrigger is unlatched by a solenoid actuator in response to an inclination responsive switch, such as a mercury switch. 
     Some embodiments include a mechanical inclination sensor that detects a vehicle tilting to a predetermined limit by contacting the surface upon which the vehicle is traveling. 
     In some embodiments, an outrigger comprises an inflatable bladder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial rear end view of a vehicle, showing an outrigger attached to the left side of the vehicle, wherein the outrigger is in a stored position. 
     FIG. 2 is the same as FIG. 1, but with the vehicle tilted and the outrigger in a deployed position. 
     FIG. 3 is a partial rear end view of a vehicle showing a cross-sectional view of an outrigger of another embodiment. 
     FIG. 4 is the same as FIG. 3, but with the vehicle tilted and the outrigger in a deployed position. 
     FIG. 5 is a left side view of a forklift vehicle with another embodiment of an outrigger attached to the left side of the vehicle, wherein the outrigger is in a stored position. 
     FIG. 6 is a partial rear end view of the vehicle of FIG.  5 . 
     FIG. 7 is the same as FIG. 6, but with the vehicle tilted and the outrigger in a deployed position. 
     FIG. 8 is a left side view of a forklift vehicle with another embodiment of an outrigger attached to the left side of the vehicle, wherein the outrigger is in a stored position. 
     FIG. 9 is a partial rear end view of the vehicle of FIG.  8 . 
     FIG. 10 is the same as FIG. 9, but with the vehicle tilted and the outrigger in a deployed position. 
     FIG. 11 is a left side view of a forklift vehicle with an outrigger attached to the left outer mast of the forklift, wherein the outrigger is in a stored position. 
     FIG. 12 is a front view of the vehicle of FIG.  11 . 
     FIG. 13 is the same as FIG. 12, but with the vehicle tilted and the outrigger in a deployed position. 
     FIG. 14 is a left side view of a forklift vehicle with an inflatable outrigger in its deflated stored position. 
     FIG. 15 is a rear view of the vehicle of FIG.  14 . 
     FIG. 16 is the same as FIG. 15, but with the vehicle tilted and the outrigger in its deployed, inflated position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     To prevent a vehicle from overturning, an outrigger  10  includes an engaging member such as arm  12  that by its own weight automatically swings between a stored position (FIG. 1) and a deployed position (FIG.  2 ), depending on the inclination of the vehicle to which it is mounted. The term, “vehicle” refers to any wheeled device capable of travel of which examples include, but are not limited to, a forklift truck  14 , a shopping cart, a riding lawn mower/tractor and a wheelchair. The terms, “automatic” and “automatically” refer to an action initiated by a mechanical or electrical device as opposed to being initiated manually. 
     In one simple exemplary embodiment, a pinned bracket  16  pivotally attaches arm  12  to a side  18  of forklift  14 . Under its own weight, arm  12  hangs generally vertically from bracket  16  along side  18  when forklift  14  is level, as shown in FIG.  1 . In the event that forklift  14  tips sideways about its wheels  20  to a predetermined limit, as shown in FIG. 2, arm  12  continues to hang generally vertically to place a distal end  22  of arm  12  up against the ground or surface  24  upon which forklift  14  travels. This helps keep forklift  14  from tipping beyond the limit. Although outrigger  10  is shown only on the left side of forklift  14 , in most cases similar or identical outriggers are installed on both sides of the vehicle. 
     To limit the extent to which arm  12  swings outward from vehicle  14 , an optional brace  26  (e.g., a rigid elongated member as shown or a flexible one such as a chain, cable or cord) extending from arm  12  includes a catch  28  that engages a protruding stop pin  30  when arm  12  is in its deployed position. When brace  26  is relatively light, arm  12  tends to hang vertically as shown in FIG.  1 . However, it is well within the scope of the invention to provide brace  26  with substantial weight to create a moment about pinned bracket  16  to urge arm  12  outward to its deployed position. In such a case, a releasable latch could be used to hold arm  12  in its stored position until vehicle  14  tips to the predetermined limit. At that point, the latch would move to release arm  12 , so that the weight of brace  26  could quickly push arm  12  out to its deployed position. Various biasing elements can also be added to urge arm  12  outward. Examples of biasing elements include, but are not limited to mechanical springs; gas springs; such as bladders, diaphragms, and piston/cylinder; hydraulic piston/cylinder; electromechanical actuators; and weights. Also, the latches can assume a variety of forms, a few examples of which are described with reference to other embodiments of the invention. 
     For example, an outrigger  32  (FIGS. 3 and 4) includes a latch  34  and a compression spring  36  that allow an extendible arm  38  to remain in a fully retracted stored position (FIG. 3) until vehicle  14  tips beyond a limit, at which point arm  38  rapidly moves to a deployed position (FIG.  4 ). Arm  38  slides linearly within a cylindrical housing  40  that is attached to a bottom portion  42  of forklift  14 . Spring  36  serves a biasing element that urges arm  38  to extend by pushing up against a shoulder  44  of arm  38 . Although latch could be mechanically actuated (i.e., non-electrical), in this example, it is solenoid actuated (i.e., electrically actuated). Solenoid actuated latch  34  is connected in series with a power source  46  (e.g., a battery) and a switch such as a normally open electrical switch  48  that changes state in response to forklift  14  tilting to the predetermined limit. In this case, normally open contacts are used; however, it is well within the scope of the invention to use normally closed contacts with an appropriate response mechanism. Switch  48  serves as a sensor that provides a reaction in response to vehicle  14  tipping beyond a limit, whereby the reaction is a change in the electrical continuity of switch  48 . In this example, switch  48  is a conventional mercury switch; however, switch  48  is schematically illustrated to represent a variety of other switches responsive to a vehicle tipping. Solenoid  34  includes a normally extended plunger  50  that retracts into a housing  52  upon being energized. 
     In operation, plunger  50  is normally extended to engage a distal end  54  of arm  38  to hold arm  38  within housing  40  against the opposing force exerted by spring  36 . When vehicle  14  tips far enough to close the electrical contacts of switch  48  (thereby energizing solenoid  34 ), plunger  50  retracts to release end  54 , so spring  36  rapidly pushes arm  38  outward to its deployed position. In this example, distal end  54  is a roller that minimizes any frictional dragging force that may develop between it and surface  24  as forklift  14  continues to move forward while leaning against extended arm  38 . Once forklift  14  rights itself, switch  34  can be forced closed (e.g., manually tilting the switch or shunting its contacts) to temporarily retract plunger  50  until arm  38  is manually pushed back to its stored position. 
     In FIGS. 5-7, an outrigger  56  combines a mechanical latch  58  with an inclination sensor having a mechanical trigger  60 . In this embodiment, an upper bracket  62  and a lower bracket  64 , attached to forklift  14 , engages a shaft  66  to pivotally mount an arm  68  about an axis  70  having a vertical component (i.e., axis  70  is out of parallel with a horizontal plane). To assist in deploying distal end  74  of arm  68  from its stored position (FIGS. 5 and 6) to its deployed position (FIG. 7) a torsional spring  72 , disposed about shaft  66 , includes one end engaging arm  68  and an opposite end engaging forklift  14 . A hinge  76  pivotally connects a member  78  to forklift  14 . Member  78  includes latch  58  that releasably engages distal end  74  of arm  68  and includes trigger  60  that engages surface  24  to sense that vehicle  14  has tipped to its predetermined limit. 
     Under normal operation, member  78  pivots downward to a hold position where latch  58  holds end  74  at its stored position against the urging of spring  72 , while trigger  60  is slightly (e.g., half inch) above surface  24 , as shown in FIGS. 5 and 6. When forklift  14  tilts to a predetermined limit, as shown in FIG. 7, trigger  60  engaging surface  24  rotates member  78  upward (in relation to forklift  14 , as shown in phantom in FIG. 6) to a release position where latch  58  releases end  74 , which allows spring  72  to rapidly swing arm  68  outward to its deployed position. The downward extending portion of trigger  60  is sufficiently offset horizontally from the side of forklift  14  to allow clearance between the tip of end  74  and trigger  60  as arm  68  swings around. As arm  68  swings from its stored position, it engages a stop  80  that prevents arm  68  from rotating past its deployed position. Once in the deployed position, distal end  74  of arm  68  engages surface  24  to limit the tilting of forklift  14 . The horizontal offset distance between trigger  60  and forklift  14 , and the vertical ground clearance between the bottom of trigger  60  and surface  24  establishes the predetermined limit of tilting. Outrigger  56  is returned to normal operation by manually swinging arm  68  back to its stored position, and lowering member  78  so latch  58  engages end  74  to hold arm  68  in place. 
     To provide greater ground clearance for travel, an outrigger  82  includes a vehicle-mounted track  84 , as shown in FIGS. 8-10. Outrigger  82  includes an engaging member such as arm  86  having an upper end  88  pivotally attached to a carriage  90 , which in turn is coupled for vertical translational movement along track  84 . Track  84  is attached to forklift  14  by way of an upper bracket  91  and a lower bracket  93 . A brace  92  having one end  94  pivotally attached to vehicle  14  has an opposite end  96  pivotally attached to arm  86  at an intermediate point  98  between upper end  88  and a lower distal end  100 . A compression spring  102  disposed about track  84  and pushing carriage  90  downward urges outrigger  82  to its deployed position of FIG.  10 . 
     In operation, normally extended plunger  50  of solenoid latch  34  holds distal end  100  in a stored position, as shown in FIGS. 8 and 9. When vehicle  14  tilts to the predetermined limit, power supply  46 , through switch  48 , energizes solenoid latch  34  to release end  100 . Spring  102  then pushes carriage  90  down along track  84  to rapidly deploy arm  86 , as brace  92  pivots about end  94  and point  98 . Arm  86  in a deployed position is shown in FIG.  10 . Once deployed, to prevent surface  24  from pushing arm  86  back up along track  84  as forklift  14  tilts, a catch  95  engages an upper edge of carriage  90 . Catch  95  is cantilevered from lower bracket  93  by way of a flexible extension  97  (e.g., a spring-steel strap) and includes a tapered leading edge  99  that allows carriage  90  to slide downward into engagement with catch  95 . Bending extension  97  outward to disengage catch  95  from carriage  90  allows outrigger  82  to be manually returned to its stored position in a manner similar to that described with reference to outrigger  32 . 
     To provide vehicle  14  with more side clearance for maneuvering within narrow aisles, an outrigger can be mounted to an outer mast  104  of forklift  14 , as shown in FIGS. 11-13. An outrigger  106 , for example, includes an engaging member such as arm  108  with an upper end  110  attached to mast  104  by way of a pivotal bracket  112 . Arm  108  serves as a guide track along which a carriage  114  can move. A compression spring  116  disposed about arm  108  urges carriage  114  downward to a distal end  118  where a stop  120  is installed to limit the downward travel of carriage  114 . A dual-brace  122  pivotally attached to mast  104  at a point  124  and pivotally attached to carriage  114  at point  126  causes end  118  of arm  108  to alternately move towards and away from mast  104  as carriage  114  moves up and down respectively. Normally extended plunger  50  of solenoid latch  34  holds dual-brace  122  back, which holds distal end  118  in a stored position, as shown in FIGS. 11 and 12. When vehicle  14  tilts to the predetermined limit, power supply  46 , through switch  48 , energizes solenoid latch  34  to release dual-brace  122 . Spring  116  then pushes carriage  114  down along arm  108  to rapidly deploy arm  108 , as dual-brace  122  pivots about points  124  and  126 . Arm  108  in a deployed position is shown in FIG.  13 . Outrigger  106  is manually returned to its stored position in a manner similar to that described with reference to outrigger  32 . 
     To provide an outrigger with rapid deployment and a minimum number of mechanical moving parts, outrigger  128  of FIGS. 11-13 includes an engaging member that comprises an inflatable bag  130 . Bag  130  is similar to what is known as an “air bag” used for protecting occupants of an automobile in a collision. However, the size and strength of bag  130  are such that bag  130 , when inflated, can inhibit forklift  14  from overturning by serving as a bolster between the side of forklift  14  and surface  24 . Bag  130  is normally deflated and folded into a collapsed, stored position, as shown in FIG.  12 . To protect the deflated bag, a cover  132  preferably extends over bag  130  and is hinged (e.g., hinges  134 ) or otherwise moveably attached to the side of forklift  14  to allow rapid, substantially unrestricted deployment of bag  130 . To deploy or inflate bag  130 , a pressurized, fluid-filled canister  136  is connected by way of a valve  138  to discharge a fluid (e.g., air, carbon dioxide, nitrogen, etc.) into bag  130 . As bag  130  inflates, a distal end  140  of bag  130  engages surface  24 , as shown in FIG.  13 . Valve  138  is normally closed when forklift  14  is substantially upright, but then rapidly opens when forklift  14  tilts to a predetermined limit. In one embodiment, for example, a solenoid opens valve  138  in response to a circuit comprising power supply  46  and tilt switch  48  whose operation has already been explained with reference to other embodiments. It should be noted, however, that other schemes for rapidly opening a valve (electromechanical or mechanical) could also be used. 
     Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that various modifications are well within the scope of the invention. For example, the various styles of latches, tilt sensors, and engaging members can be interchanged and combined to create a variety of outriggers that still accomplish the same purpose of inhibiting a moving vehicle from overturning. Therefore, the scope of the invention is to be determined by reference to the claims that follow.