Abstract:
An all-terrain fire fighting apparatus has a high power-to-weight ratio, a hydraulic skid steer drive system, a drive-by-wire control system, a proportionally joystick controlled nozzle turret, and a 1500 psi foam injecting water supply system which supplies the nozzle turret and a high-pressure hose mounted on a reel. To dissipate heat load from the fire fighting apparatus systems, the fire fighting apparatus cooling system employs a cooling shroud in the form of a box with multiple system radiators stacked on one face of the box and the remaining faces containing exhaust fans mounted to draw air out of the box and through the stacked heat exchangers. The fire fighting apparatus is capable of being operated remotely by means of onboard GPS, real-time imaging, and inputs to the joystick controller and fire fighting apparatus drive-by-wire system.

Description:
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0001]    The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Agreement No. FA8650-06-C-5910 awarded by AF Research Laboratory on Jul. 27, 2006. 
     
    
     CROSS REFERENCES TO RELATED APPLICATIONS 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to fire fighting apparatus in general and to off-road all-terrain fire fighting apparatus in particular. 
         [0004]    Although fires are principally a problem for urban areas, there are areas associated with transportation systems and natural resources where fires can result in substantial monetary damages or loss of life. Aircraft fires in particular can result in the loss of life and very valuable aircraft. It is also well known that aircraft are exposed to the greatest hazards while taking off and landing, and are inherently lightweight structures containing relatively large amounts of flammable liquids. While accidents involving aircraft sometimes occur on the runway or taxi strips, often enough a plane lands short of the runway, or runs off the end of the runway. In either case the planes are often beyond access by over the road vehicles. Off-road fire engines are well-known, both for fighting aircraft fires and for fighting brushfires and forest fires. 
         [0005]    The off-road fire engine has some unique requirements and difficulties. Principal among these is the difficulty of all terrain navigation, which tends to limit the size of the vehicle and the amount of water that can be carried in the fire engine. One technology for dealing with a limited water supply is the use of a foaming agent, another approach is to use high-pressure water at the neighborhood of 1500 psi to create a water fog. Joystick controlled water nozzles are also known to provide better control over the nozzle and to facilitate remote operation of the nozzle. However, joystick controllers currently used to control high pressure water nozzles are relatively simple devices using limit switches to drive the nozzle in two directions at a constant rate and without advanced programming capabilities. Further, while water nozzles can be controlled remotely, the fire engine itself must be manually operated. What is needed is a fire fighting apparatus suitable for fighting off road fires which incorporates the latest developments in firefighting techniques with advanced control systems which allow flexibility in configuration and even remote operation. 
       SUMMARY OF THE INVENTION 
       [0006]    The all-terrain fire fighting apparatus of this invention has an engine frame which has a forward end and an aft end. An operator cab is mounted to the forward end of the engine frame and a rear cab covers the vehicle engine and equipment. Each side of the engine frame mounts four all-terrain traction wheels connected to a common drivetrain driven by a hydraulic drive motor. Each drive motor is driven by a separate hydraulic drive pump. The hydraulic drive pumps are connected to a main gearbox mounted to the front of a 170-190 hp diesel turbo charged engine, The gear box is arranged to be driven by the engine crankshaft. The fire fighting apparatus is steered by differentially controlling the hydraulic motors using a so-called skid steer system. Mounted in front of the cab is a high-pressure nozzle turret, which is proportionately controlled in two axes by a joystick. The joystick provides inputs to a programmable controller which provides a proportional control and programmable functionality. Mounted under the cab is a diesel fuel tank, followed by a hydraulic fluid tank. Mounted above a central portion of the engine frame is a 300 gallon water tank which also incorporates a 36 gallon foam additive tank. The foam additive tank supplies foam additive to a low pressure positive displacement piston pump driven by an electrically controlled motor which allows foam additive to be metered to the low-pressure side of a high-pressure water pump. The high-pressure water pump has a capacity of about 60 gallons per minute at 1500 psi. The high-pressure water pump receives water from the water tank and foaming agent from the foaming agent tank and is driven by a hydraulic motor. The high-pressure pump drive motor is in turn connected to a third hydraulic pump which is mounted to the main gearbox beneath the two drive motor pumps. The high-pressure water pump supplies water to the forward mounted nozzle turret, about 60 gallons per minute, and to a hose reel mounted at the rear of the fire fighting apparatus, about 20 gallons per minute. If the hose is used at the same time as the nozzle the forward mounted nozzle turret is limited to 40 gallons per minute. 
         [0007]    Operation of the fire fighting apparatus employs a drive-by-wire control system with a single proportional pedal control for forward movement and braking, and a steering wheel which provides a control signal to the fire fighting apparatus controller. The engine controller in turn controls the flow of hydraulic drive fluid to the traction motors to control the speed and direction of the fire fighting apparatus. The use of the computer-controlled interface between input sensors and the systems being driven allows the use of programmed functions, both in the operation of the water nozzle turret mounted to the forward bumper and in the operation of the vehicle itself. 
         [0008]    It is a feature of the present invention to provide an all-terrain fire fighting apparatus of improved functionality. 
         [0009]    It is another feature of the present invention is to provide an all-terrain fire fighting apparatus which can be operated remotely, or with one or two operators. 
         [0010]    It is yet another feature of the present invention to provide an all-terrain fire fighting apparatus of small size but high fire suppression capability. 
         [0011]    Further features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an isometric view of the all-terrain fire fighting apparatus of this invention. 
           [0013]      FIG. 2  is a schematic view of the systems on the all-terrain fire fighting apparatus of  FIG. 1 . 
           [0014]      FIG. 3  is an isometric view of the cooling system shroud and the radiators mounted thereto employed by the fire fighting apparatus of  FIG. 1   
           [0015]      FIG. 4  is a flow diagram of the proportional joystick controller used to control a forward nozzle turret of the all-terrain fire fighting apparatus of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    Referring more particularly to  FIGS. 1-3 , wherein like numbers refer to similar parts, an all-terrain fire fighting apparatus  20  is shown in  FIG. 1 . The fire fighting apparatus  20  has a frame  22  which has a forward end  28  to which a forward cab  24  is mounted, and an aft end  25  to which an aft cab  27  is mounted and arranged to cover the aft end. As shown schematically in  FIG. 2 , four traction wheels  26  are on each side of the frame. The traction wheels  26  are divided into two groups, a group of four starboard wheels  30  and a group of four port wheels  32 . The starboard wheels  30  are driven by a starboard drivetrain  34  and the port wheels  32  are driven by a port drivetrain  36 . Each drivetrain  34 ,  36  is comprised of a positive displacement hydraulic traction motor  38  which drives a shaft  40  through a gearbox  42 . The shaft is formed by four interconnected right angled gearboxes  44  connected by linking shafts  46 . Each right angled gearbox  44  drives one wheel  26 . Because the port and starboard wheels are driven independently, the vehicle can be skid steered, like a battle tank, such that it can spin in place. Further, because all the wheels are driven together, all the drive power supplied by the traction motor  38  of either the port or starboard side is applied to the wheel  26  with the most traction. Braking action is provided by reducing, then completely shutting off, hydraulic flow through the traction motors  38 . Without hydraulic flow to the traction motors  38  the wheels are effectively locked against rotation. 
         [0017]    A drive engine  52  is mounted to the fire fighting apparatus Frame  22  and provides power to all the vehicle systems. Each traction motor  38  is in turn driven by hydraulic traction pump  48  mounted to a main gearbox  50  which in turn is mounted to the drive shaft of a turbo-charged  170  hp Commins® diesel engine which functions as the drive engine  52 . The main gearbox  50  also provides power to a pump  54  which supplies hydraulic fluid to drive a motor  56  which is connected to a high-pressure water piston pump  58  which can supply 60 gallons per minute at a water pressure of 1500 psi. Such a high-pressure water pump is manufactured by CAT PUMPS of Minneapolis, Minn. 
         [0018]    A fire suppression system  60  is comprised of a main water tank  62  which is mounted behind the cab  24  as shown in  FIG. 1 . The main water tank  62  is constructed of welded polyethylene, and incorporates anti-slosh baffles to minimize slosh moments which are created by acceleration-induced waves in the water tank. The tank  62  also incorporates a 36 gallon foaming agent tank  64  which, as shown in  FIG. 2 , is connected to a low-pressure metering pump  66  driven by an electric metering motor  68  which controls the addition of foaming agent to the low-pressure inlet  70  of the high-pressure pump  58 . The main water tank  62  is also connected in water supplying relation to the low-pressure input  70  on the high-pressure water pump  58 . The output of the high-pressure pump  58  is connected to a two axis nozzle turret  72  mounted to the forward bumper  74  of the fire fighting apparatus  20 , and to a high-pressure hose  76  contained on a high-pressure hose reel  78  mounted to the aft end  25  of the fire fighting apparatus  20 . 
         [0019]    The water tank  62  has a fill/vent opening  80  which opens to the roof  81  of the fire fighting apparatus  20  as shown in  FIG. 1 , the water tank also has a fill/vent opening  82  which opens into the foaming agent tank  64 . The fill/vent openings  80 ,  82  allow the water tank  62  and the foaming agent tank  64  to be rapidly filled from overhead. As shown in  FIG. 2 , the fire fighting apparatus  20  may also refill the water tank  62  using an onboard suction pump  84  which is driven by a fill hydraulic motor  86 . The fill hydraulic motor  86  is driven by a drive motor  87  mounted to a power takeoff on the diesel engine  52 . The suction pump  84  can withdraw water from a pond or stream in the field or can return to pre-positioned water tanks positioned on improved roadways which can be resupplied by conventional tankers. The suction pump  84  is sized such that a fire fighting apparatus  20  can refill its water tank in three minutes or less. 
         [0020]    The fire fighting apparatus  20  has a gross dry weight of approximately 7,600 lbs or 10,000 lbs wet weight and thus a power-to-dry-weight ratio of over 40 hp per dry ton, which is more than twice that of typical over-the-road fire engines. The fire fighting apparatus  20  is a lightweight high-powered fire fighting apparatus which provides unique firefighting capability, however the high-powered power dissipation requires a specialized cooling system which can handle a heat load on the order of 250,000 BTUs per hour. As shown in  FIGS. 2 and 3 , the cooling system has a shroud  88  forming a trapezoidal prismatic six-sided solid. An engine liquid cooling system radiator  94  is mounted on the aft-most face  92  of the shroud  88 . An air-to-air heat exchanger  96  is positioned aft of the engine radiator which serves to pre-cool air from the engine turbocharger  90  before it is supplied to the engine air intake  98 . The shroud  88  has seven exhaust fans  102  mounted to the prismatic sides  104  of the shroud which are not covered by the heat exchangers  94 ,  96 . The shroud fans  102  draw air through the air-to-air heat exchanger  96 , the engine radiator  94 , and a fuel pre-cooler  100  positioned below the air-to-air heat exchanger  96 . The exhaust fans  102  dump the cooling air so it passes out below the vehicle and through the opening between the wheels  26 . Cooling air can also be driven through the air-to-air heat exchanger  96  and the engine radiator  94  by two fans  91  supplying 3,500 ft. 3  per minute of cooling air. As shown in  FIG. 1 , a double pass hydraulic radiator  103  is mounted to the top of the aft cab  25  beneath an aft shroud  106  and is open to the aft of the fire fighting apparatus  20 . The majority of the waste heat produced by the engine is removed with the engine exhaust through an exhaust pipe  105  extending upwardly from the engine. 
         [0021]    The control system employs a programmable controller  112  which receives sensor inputs from a steering wheel  108 , and a foot-operated acceleration/brake pedal  110  in the forward cab  24  driver compartment. The control system utilizes an IQAN-MD3 master module and software from Parker Hannifin Corporation which is a controller and software package designed for the control of hydraulic equipment. The vehicle is driven with the simple inputs from the steering wheel  108 , the acceleration/brake pedal  110 , and a reversing switch which puts the fire fighting apparatus in a reverse mode for backing up. The fire fighting apparatus  20  has a maximum speed of about 20 miles an hour and the inputs from the steering wheel  108  and pedal  110  are used to control the hydraulic pressures supplied to the drive motors  38 . A sufficiently large turning motion will result in the reversal of one of the drivetrains  34 ,  36  so that the vehicle will spin to the right or left in place. The all hydraulic drive-by-wire control system is flexible and it can be programmed to change the way the vehicle responds to control inputs. The vehicle has an onboard GPS system  122  which provides GPS coordinates and map overlays allowing the vehicle to be operated in low visibility such as caused by smoke. The vehicle has a data acquisition system  120  which includes realtime imaging equipment for documentation or remote operation of the fire fighting apparatus  20 . Because the fire fighting apparatus  20  employs a drive-by-wire control system, i.e., there is no mechanical connection between the controls in the vehicle systems, a transceiver  118  which sends real-time imaging, position data, and situation awareness data, and receives control inputs from a remote control console  124  can be used. In other words the fire fighting apparatus design lends itself to remote operation because it uses a drive-by-wire control scheme. 
         [0022]    A separate microprocessor control system  114  based on an Atmel AT89C51CC01 is utilized to provide programmable functionality to the nozzle turret  72  based on joystick  116  inputs as shown in  FIG. 4 . The joystick  116  provides analog inputs which are converted to digital position values which are then set to drive the X and Y control axes of the nozzle turret proportionately so that larger control inputs to the joystick result in faster control motions in the X and Y axes. The programmable controller can also provide additional functions such as automatic pre-programmed spray patterns as well as remembering and repeating the last control movements entered by the operator. The joystick may incorporate a third axis of freedom such as rotation of the joystick to control the amount of foam additive which is supplied to the high-pressure water pump inlet  70 . A suitable arrangement for the water turret  72  is shown in U.S. Pat. No. 6,655,613 which is incorporated herein by reference. 
         [0023]    The forward cab  24  is normally sealed by doors (not shown) and the interior of the cabin supplied by an air conditioner  126  shown in phantom in  FIG. 1 . The air-conditioning unit provides cooling and removal of dust, smoke and other contaminants. The forward windshield  128  is cooled by misting bar  130  which is supplied by a small electric motor (not shown) which draws water from the main water tank  62 . 
         [0024]    The fire fighting apparatus  20  is operated as a rapid first response vehicle, which can be operated by a driver with or without a second operator. The all hydraulic drive-by-wire operating system provides a highly maneuverable transmission free vehicle with an overland speed of approximately 20 miles an hour. The firefighting capabilities of the vehicle are greatly increased by the use of a high-pressure water system which produces a fine mist or fog of water droplets in the range of about 90% between 10 μm and 50 μm. Mist water systems provide fast removal of heat through rapid evaporation and a smothering effect by displacing oxygen with water vapor. The high surface area of the water droplets extracts heat rapidly from the fire producing a strong cooling effect. This also serves a protective function protecting people and property against the effects of radiant heat, for example isolating a portion of an aircraft which is burning from the crew cabin while personnel are being extracted. The rapid evaporation of the extremely small water droplets generates water vapor, increasing the water volume by 1,640 times and producing a localized inerting effect by depleting oxygen locally. The water mist is also effectively insulating, allowing water mist to be used directly on electrical fires. The water mist is lightweight and floats over the surface of burning hydrocarbons making water mist and an effective fire fighting agent for burning fuels. The cumulative result is that the 300 gallon water supply becomes as effective as a much larger quantity of water, and is effective for fighting a broad range of fires. High-pressure water can also be used to generate foam without the added weight and complexity of compressed air equipment. The metered addition of a foaming agent from the foam tank  64  with the metering motor  68  can be used to produce any type of foam desired. Aqueous film-forming foam (AFFF) developed by the Navy in the mid-60s is an example of a synthetic foam which has a low viscosity and spreads rapidly across the surface of most hydrocarbon fuels. The foam forms a water layer over the liquid fuel and stops the formation of flammable vapors, which is critical in providing a rapid suppression of a fire in a crash and rescue situation. 
         [0025]    The all-terrain fire fighting apparatus  20  provides the capability of fighting fires with limited manpower, as a single operator can maneuver the engine while fighting the fire by means of the bumper mounted nozzle turret  72  and the joystick  116 . The engine&#39;s rapid self-filling and high maneuverability allows even a few units, each with a single operator, to maintain continuous fire suppression operations at a considerable distance from the ends of a runway. The enclosed and air-conditioned crew cab  24  and the high maneuverability can greatly improve operator safety when operating against brush-fires which can rapidly change direction. The drive-by-wire system even allows the remote operation of the firefighting equipment. This can substantially reduce costs as standby personnel anywhere in the world can be used to augment locally available forces to respond to a fire. Remote operation also allows operation under enemy fire or in the presence of munitions. 
         [0026]    It should be understood that the fire fighting apparatus  20  incorporates numerous conventional parts associated with the systems described, for example hydraulic filters, accumulators and arrangements for recirculation of hydraulic fluids, and alternators, batteries, power supplies and starting motors. 
         [0027]    It should be understood that high-pressure water means water with a pressure of over 1000 psi to as much as 1700 psi, and a high pressure pump is a pump of the type which produces such high-pressure water. 
         [0028]    It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.