Abstract:
A system for deploying a barrier deterring approach by pedestrians to the exhaust outlet from a vehicle operates in response to exhaust temperature and stopping of the vehicle.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The primary technical field relates to vehicle mounted pedestrian guard barriers, and more particularly to a barrier which automatically deploys to divert foot traffic away from an area adjacent an exhaust pipe. 
   2. Description of the Problem 
   Diesel engine equipped vehicles have been the subject of ever more stringent requirements designed to reduce exhaust gas emissions in recent years. These tighter requirements have been directed to reducing particulate emissions among other byproducts of the combustion process. In order to reduce particulate emissions, diesel-engine equipped vehicles have come equipped with diesel exhaust particulate traps, which filter particulate matter from the exhaust stream. These filters are subject to periodic regeneration or after treatment when the build up of matter in the trap begins to unduly restrict the exhaust system. The particulate matter is oxidized in situ, which results in a substantial increase in exhaust gas temperature, potentially as high as 1000 degrees Fahrenheit. Children walking around a school bus to board the bus could inadvertently be exposed to the high temperature exhaust stream. Where buses are waiting at a school to pick up children they are typically parked in close proximity to one another to the point where there is potential for paint damage to the bus directly behind a bus equipped with an active after-treatment system. 
   SUMMARY 
   What is provided is a barrier/crossing gate which deploys adjacent the exhaust outlet on a motor vehicle, typically a school bus. The main components of an exemplary embodiment are a controller, the brake system, an exhaust pipe/stack temperature sensor, a rear bumper crossing gate/barrier and a servo system for deploying the barrier. The controller implements an interlock strategy controlling deployment and stowage of the barrier preferably using existing sensors and switches to achieve the desired functionality. When the bus comes to a stop, and the parking brake is engaged, a controller would look up the post-diesel particulate filter exhaust gas temperature as determined by a sensor to see if it exceeds a threshold level. Such sensors are commonly provided with vehicles having diesel particulate sensors. If the temperature is above the threshold level, the controller would command the rear bumper crossing gate/barrier to deploy. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the disclosure are set forth in the appended claims. The preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is an anterior view of a school bus illustrating location of the barrier of the invention. 
       FIG. 2  is a schematic of the barrier and exhaust system. 
       FIG. 3  is a block diagram schematic of a control system for a vehicle providing control over the barrier. 
       FIG. 4  is a flow chart of the interlock control strategy used to deploy and stow the barrier. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the figures and in particular to  FIG. 1 , a vehicle such as a school bus  10  is illustrated. School bus  10  is equipped with conventional exterior lamps and warning signs such as pupil warning lights  18  and a deployable stop sign  19 . School bus  10  is a diesel powered vehicle having an exhaust pipe  26 , which, due to provision for particulate trap regeneration (not shown in  FIG. 1 ) may discharge exhaust from under bumper  24  at elevated temperatures not commonly encountered by pedestrians around vehicles. During regeneration of the exhaust, and at times when pedestrians might be passing by the back of bus  10  a barrier  22  swings out from bumper  24  to give warning to passers by of the possibility of encountering high temperature exhaust gas. The barrier  22  and exhaust  26  are preferably positioned not to interfere with the use of a rear door  20 . 
     FIG. 2  illustrates barrier  22  swung outwardly from bumper  24  on a hinge  28  installed on or in the bumper. If desired, a catch (not shown) may be provided to lock the barrier  22  up against the bumper or instead of a section of the bumper. A servo  30  is mechanically coupled to the barrier  22  or hinge  28  to deploy or retract and stow the barrier. A gear and sprocket mechanism  32  linking the servo and hinge  28  conveniently provides for positioning the barrier  28 . Hinge  28  is preferably positioned directly above exhaust pipe  26  at its point of discharge so that the barrier  22  is aligned when deployed with the exhaust gas stream leaving the pipe. The system for extension of the barrier is intended as being exemplary only, other methods, such as a hydraulically actuated push rod could be used. 
   Exhaust gas temperature sensor  127  is located in exhaust pipe  26  downstream from a diesel particulate filter  33 . The diesel particulate filter  33  is periodically regenerated raising the temperature of the exhaust gas several hundred degrees Fahrenheit. Exhaust gas temperature is a key trigger in the preferred embodiment for deploying the barrier  22 . 
     FIG. 3  is a block diagram schematic of a control system for vehicle  10  in so far as it relates to operation of barrier  22 . The control system represents a possible control system in which most major functions relating to the invention have been illustrated as located with individual controllers for execution. Those skilled in the art will realize that in many cases a function may be located in a higher level controller, for example the speed sensing function, which is illustrated by a speed sensing device  121 , may be implemented by a drive shaft tachometer (not shown) attached to the transmission  140  or drive shaft and monitored by the transmission controller  140 A. 
   The control system includes an electrical system controller (ESC)  130 , or equivalent, which may be taken to serve as a supervisory controller over the control system. ESC  130  and other controllers communicate with each over a bus  110 , which operates in accord with a protocol such as the Society of Automotive Engineers (SAE) J1939 protocol relating to controller area networks (CAN). The controllers may be dedicated controllers, such as engine controller  115 , or they may be generic controllers which are programmed to carry out particular operations or which operate as slaves of the ESC  130 . The assignee of this application markets generic controllers for controller area network applications, termed Remote Power Modules, which can be readily programmed from an external diagnostic port  136  or by the electrical system controller  111  in response to particular hardware attached to the remote power module. Barrier  22  may be deployed by a barrier positioning mechanism  119 , which may include servo  30  under the control of a barrier controller  117 , which may be a remote power module. Typically any function which can be carried out by a generic controller may also be carried out by the electrical system controller (ESC)  130 , provided output ports are available for connection of operational hardware to the ESC. Thus the barrier positioning mechanism may be under the direct control for the electrical system controller  130 . 
   In an SAE J1939 CAN context, data buses may be private or public. Data bus  110  may be taken to be a conflation of a public and private bus. A system topology will generally provide that the generic controllers are connected to the private bus and the dedicated controllers are connected to the public bus. The ESC  130  is connected to both buses and acts as a bridge between the buses. The general principal here is that generic controllers are typically used to provide customer specific functions, and use a customized communication set, which is not understandable by the dedicated controllers. This in turn requires the ESC  130  to handle translation between the buses, where required, before data is exchanged between dedicated and generic controllers. The mechanism of such data exchanges is outside the scope of the present invention. 
   The preferred embodiment of the present invention provides for deployment of the barrier  22  based on an interlock strategy. An interlock strategy using existing sensors and switches can be set up to achieve the desired functionality. When the bus  10  comes to a stop, and the parking brake  103  is engaged, ESC  130  would read the temperature reported by a post-diesel particulate filter temperature sensor  127  to see if it exceeds a threshold level. If the temperature is above the threshold level, the ESC  130  would command the barrier controller  117  to deploy the rear bumper crossing gate/barrier  22 . The parking brake  103  is illustrated as connected to a parking brake actuator  103 A, however, commonly, parking brake  103  position is reported directly to ESC  130 . The exhaust temperature sensor  127  communicates readings to the engine controller  115 , which normally executes the steps required to initiate diesel particulate filter regeneration, such as running diesel engine  121  rich to supply fuel and heat to the filter. Setting of the park brake is required in some jurisdictions during embarkation and disembarkation of passengers and thus its use is taken as an indication that passenger boarding operations are occurring. It is possible that other indicators could be used. 
     FIG. 4  illustrates implementation of the interlock strategy as a flow chart. The interlock strategy is based on determining that the vehicle is in an operational configuration consistent with the possibility that passengers are disembarking or embarking and that the diesel particulate filter is in fact being regenerated. Absence of any of the three conditions results in stowing the barrier. After starting vehicle speed is checked at step  402  to determine if it falls below a minimum V(C). If it does, the YES branch is taken to step  404  where the position of the park brake is checked. If the park brake is set the YES branch is taken from step  404  to an exhaust gas temperature determination step  406 . When exhaust gas temperature downstream from a diesel particulate filter indicates that regeneration of the filter is occurring, the YES branch is taken to step  408  indicating deployment of the barrier  22 . The NO branch from any of steps  402 ,  404 ,  406  results in restowing of the barrier, if deployed, or confirmation that the barrier is stowed. Following steps  408  and  410  the routine loops back to step  402 . All of the interlocks must continue to be satisfied for the barrier to remain deployed. 
   The rear crossing gate/barrier of the invention deploys as a means to detour children away from the exhaust discharge point while the bus is parked for loading or keep another bus from parking too closely behind. This protects the children and the paint on other vehicles. 
   The preferred embodiment described here is not intended to limit the scope of the claims, and various changes and modifications can be made thereto without departing from the spirit and scope of those claims.