Abstract:
An auxiliary fuel tank system includes a permanent pressure tank for natural gas or propane is mounted on a vehicle such as a fork lift truck. The auxiliary tank is connected through fuel lines to a replaceable portable tank which supplies fuel to the auxiliary tank through check valves and a valve mechanism which may be turned on and off. The auxiliary tank is filled upon initial attachment of the portable tank to the fuel line for the truck. After filling the auxiliary tank, the valve mechanism is closed only to be reopened upon exhaustion of fuel from the portable tank. Fuel lines connect the respective tanks to the engine thereby permitting operation of the engine, even upon exhaustion of fuel from the portable, replaceable tank.

Description:
RELATED APPLICATIONS 
     This application is a continuation of Warth U.S. Ser. No. 09/103,425, filed Jun. 24, 1998 and assigned to the Spare Tank Co., Inc., which issued as U.S. Pat. 5,975,574 to Warth on Nov. 2, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates to an auxiliary fuel system for vehicles such as fork lift trucks and the like. 
     Fork lift trucks typically use pressurized tanks filled with propane gas (or natural gas) as a fuel source to operate the internal combustion engine of the vehicle. The use of propane gas or natural gas for such vehicles is desirable in order to reduce or control emissions of combustion products in their useful environment such as warehouses and the like. Typically, a pressurized, propane gas tank is mounted on a lift truck, for example, and attached to a fuel line that, in turn, is connected to the internal combustion engine of the lift truck. The pressurized fuel tank is typically removable and replaceable and includes enough pressurized fuel to operate the truck for a full shift or an eight hour day. However, the operator of the lift truck cannot always predict when and where the fuel in the tank will be consumed and exhausted. Thus, it may be necessary to tow the lift truck back to a refueling center where the empty propane fuel tank is removed and replaced by a full tank. Alternatively, the empty propane fuel tank from the fork lift truck may be removed and carried to a filling station for refilling and return. 
     In review, on standard fork lift trucks in most warehouses in the United States, the usual fuel utilized by the truck is propane gas and/or natural gas. The gas is provided from a refillable portable tank which is supported or mounted on the truck and which is replaced from time to time as the tank becomes empty. For maximum utilization, a lift truck is operated until its tank becomes empty. At that time, the operator typically removes the empty tank and physically carries it to a storage area where it is exchanged for a full tank and carried back to the lift truck, mounted on the truck, and attached to the proper fuel line. Alternatively, the lift truck can be towed to the fuel tank storage area. 
     In any event, fuel tank replacement is a time consuming job and may take upwards of thirty minutes in order to complete. Consequently, a system devised to reduce the time for exchanging fillable portable fuel tanks for lift trucks and for other vehicles is desirable. Thus, there has developed a need for an improved fueling system for fork lift trucks and other vehicles such as prime movers, automobiles, trucks and buses, and vehicles of the type which use propane gas or natural gas provided from a pressurized portable or replaceable fuel tank. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention comprises an auxiliary fuel tank which is maintained permanently on board a vehicle such as a lift truck. The tank is connected through a fill line to the fuel feed line that normally provides fuel to the engine from a portable, replaceable, main, fuel tank. The connection to the fuel feed line is through a tee connection, or tee. A check valve permits fuel in the fuel feed line from the portable fuel tank to flow unidirectionally into the auxiliary fuel tank when the portable tank is initially attached or mounted on the vehicle. Once the fuel pressure in the auxiliary tank and the portable tank are equalized (indicating that the auxiliary tank has been substantially filled with propane or natural gas) a valve mechanism is operated to isolate the auxiliary fuel tank from the fuel feed system to the engine. The valve mechanism remains in the “off” position until the portable, main fuel tank supply is exhausted. Thereafter, the valve mechanism is opened and a fuel line from the auxiliary tank feeds fuel into the engine directly through a separate line or through the main fuel feed line. This enables the truck operator to continue operation of the lift truck for a short time period and also permits the operator to move the truck to a refueling station where the portable fuel tank may be replaced. The capacity of the auxiliary fuel tank is typically at least 2% of the capacity of the portable fuel tank, but less than 10%. This enables the vehicle or truck to have an auxiliary fuel supply for at least 10-15 minutes of operation thus permitting an operator in a warehouse adequate time to move the vehicle expeditiously to a refueling center. 
     Thus, it is an object of the invention to provide an auxiliary fuel tank system for fork lift truck and other vehicles. 
     It is a further object of the invention to provide an auxiliary fuel tank system which is permanently mounted on a vehicle, such as a fork lift truck, and which provides an isolated supply of auxiliary fuel available upon the exhaustion of fuel from a replaceable, portable, main fuel tank that is mounted on the vehicle. 
     A further object of the invention is to provide an auxiliary fuel tank which is automatically filled upon placement of a portable fuel tank on the vehicle with the opening of a manual valve interconnecting the portable tank and the auxiliary fuel tank. 
     Yet, another object of the invention is to provide an auxiliary fuel tank which is isolated by means of a manually operated valve mechanism subsequent to being filled from a portable fuel tank through interconnecting lines that connect to the auxiliary tank as well as the engine of the vehicle. 
     Yet another object of the invention is to provide an auxiliary fuel tank system which is economical, easy to manufacture and incorporate in existing vehicles, easy to operate and which enables an operator to easily inject auxiliary fuel into an internal combustion engine system of a vehicle upon exhaustion of fuel from a portable, main fuel tank. 
     These and other objects, advantages and feature of the invention will be set forth in the detailed description which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the detailed description as follows, reference will be made to the drawing comprising the following figures: 
     FIG. 1 is an isometric view of a typical lift truck incorporating a portable, main fuel tank as well as the permanent auxiliary fuel tank and interconnecting lines, valves and other mechanism associated therewith; 
     FIG. 2 is a diagrammatic view of a first embodiment of the auxiliary fuel tank system of the invention; 
     FIG. 3 is a diagrammatic view of a second embodiment of the auxiliary fuel tank system of the invention; and 
     FIG. 4 is a diagrammatic view of a third embodiment of the auxiliary fuel tank system of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 depicts a typical fork lift truck  10  of the type which utilizes propane gas cylinders or tanks as a source of the fuel for the internal combustion engine which drives the truck. Thus, a truck  10  includes a fork lift mechanism  12 . The fork lift truck  10  also includes an internal combustion engine, schematically illustrated as engine  14 . A fuel line  16  provides propane fuel through a regulator  18  from a portable, removable, main propane tank  20 . Typically the tank  20  will include adequate propane fuel or natural gas fuel for operating the engine  14  of the fork lift truck  10  for a full eight hours in a warehouse environment. The tank  20  is removably mounted on a deck  22  of the truck  10  and is thus replaceable whenever fuel is exhausted therefrom. In addition, the fork lift truck  10  includes a bracket or cage  24  on deck  22 . The bracket or cage  24  serves multiple functions of providing roll bar protection for the operator of the truck  10 , a mount for auxiliary fuel tank as described below, and protection for the main tank  20 . 
     Permanently mounted on the bracket or cage  24  is an auxiliary or spare fuel tank  26 . The auxiliary tank  26  is connected with the removable or portable tank  20 , as described in greater detail hereinafter. Various embodiments of the connections between the portable tank  20 , the permanent auxiliary or spare tank  26  and the engine  14  are described. 
     FIG. 2 illustrates a first embodiment of the invention. The cage or bracket  24  includes opposed, spaced uprights  28  and  30  and a top, protective cross brace  32 . Tank  20 , which is the removable or portable tank, is positioned intermediate the uprights  28  and  30  and beneath the cross bracket or brace  32  on the deck  22 . In this fashion, the portable tank  20  is protected in the event of rollover or some other accident which might expose the tank  20 . Thus, tank  20  is mounted in a typical manner on the fork lift truck  10  with a connection fitting  34  adapted for connection with a fuel line  36  to the engine  14 . Typically the fitting  34  includes a manually operable valve which remains closed until connected to the line  36 . The fitting  34  may also have a quick connect feature. 
     The line  36  is connected to a tee  38 . The tee  38  includes an inlet  40 , a first outlet  42  and a second outlet  44 . The first outlet  42  connects through a unidirectional check valve  46  which provides for fuel flow in the direction indicated by the arrow in FIG.  1 . The check valve  46  feeds into main fuel line  48  which, in turn, connects through an inlet  50  of a tee  52 . The tee  52  includes an outlet  54  connected to engine fuel line  56  which connects through a regulator  58  that controls fuel pressure to engine  14 . 
     The spare or auxiliary tank  26  is permanently mounted on an upright  28 . A draw tube  59  extends into tank  26 . The auxiliary tank  26  further includes a high pressure release valve  60  designed to release the pressure from the tank  26  in the event the pressure exceeds a predetermined value. The tank  26  further includes a manual shut off valve  62  connected to the high pressure relief valve  60 . A safety collar  61  on the tank  26  protects the valve  60  and valve  62 . The manual shut off valve  62  is normally maintained in the open position and is an extra safety feature. An auxiliary fuel line  64  connects from valve  62  to an inlet  66  of a tee  68 . The tee  68  further includes an inlet  70  through line  72  from the outlet  44  of tee  38 . Intermediate the outlet  44  in fuel line  72  is a check valve  74 . Check valve  74  permits unidirectional flow therethrough to the auxiliary tank  26  by way of the tee  68 . 
     The tee  68  further includes an outlet  76  connected to an auxiliary fuel line  78  that is directed through a valve mechanism  80  having an outlet line  82  to inlet  84  of the tee  54 . Normally, the valve mechanism  80  is in the closed position so that when the portable tank  20  is attached to the system, propane fuel will flow through the check valve  74  into the tank  26  and pressurize the tank  26 . The auxiliary fuel line  78  will also be pressurized, but fuel will not be able to flow to the regulator  58  through line  78 . However, propane from the portable tank  20  will also flow through the check valve  46  and through the regulator  58  via the described line  48 , tee  52  and line  58 . 
     When the fuel in tank  20  is exhausted, the operator of the fork lift truck or the vehicle merely opens the valve mechanism  80 . This permits auxiliary fuel to flow through that valve  80  and through the tee  52  to the regulator  58  and then to the engine  14 . The check valve  46  will prevent back flow into the tank  20  as will the check valve  74 . The auxiliary fuel tank  26  may thus be utilized to provide fuel to the engine  14  until tank  20  is replaced. When the tank  20  is to be removed, the valve mechanism  80  is closed. The propane tank  20  is removed and replaced. Upon replacement of propane tank  20 , valve mechanism  80  is closed and fuel will then flow through check valve  74  into the auxiliary fuel tank  26  permanently mounted on upright  28 . In this manner, the fuel in the auxiliary tank  26  is replenished after usage and subsequent to exhaustion of the fuel in the removable, portable tank  20 . After tank  26  is filled as described, the system is ready for operation. 
     FIG. 3 discloses a second embodiment of the auxiliary fuel system of the invention. In FIG. 3, like components are labeled with like numbers. Thus, replaceable, portable tank  20  connects through a connection fitting  34 . Auxiliary fuel tank  26  is mounted on an upright (not shown), The emergency shut off valve  62  is combined with a high pressure relief valve  64 . The fuel from the tank  20  as well as the tank  26  ultimately feeds into a fuel line  56  that connects with a fuel regulator  58  in the line connected to the engine  14 . In the embodiment of FIG. 3, however, the main portable tank  20  connects through a check valve  86  and a tee  88  having an inlet  90  and an outlet  92  to the line  56 . The other outlet or branch  94  of the tee  88  is connected to the auxiliary tank  26  through a line  96  manual valve mechanism  98  and line  100 . With the design of FIG. 3, the manual valve mechanism  98  is maintained in the open position upon initial attachment of the propane or natural gas tank  20 . Gas will then flow through the check valve  86  and through the manual valve  98  to fill the auxiliary or spare tank  26 . Valve  98  may then be closed. Fuel will likewise thus flow through the tee  88  to the regulator  58  to provide fuel to the engine  14 . When fuel is exhausted in tank  20 , valve mechanism  98  is open to permit fuel to flow through the tee  88  to the regulator  28 . Check valve  86  prevents back flow into the tank  20 . The cylinder or tank  20  may then be replaced. FIG. 4 illustrated yet a further embodiment of the invention wherein like components are labeled with like numbers. Thus, the portable, replaceable tank  20  provides fuel through a connection  34  and a check valve  86  to a tee  88  connected to a line  56  feeding into a regulator  58  in the fuel line to the engine  14 . Auxiliary tank  26  connects through an emergency shut off  62  and a high pressure release valve  64  to the tee  88 . In this circumstance, the emergency shut off valve  62  is maintained in the open position upon initial attachment of the portable tank  20  to the system. Thereafter, the emergency shut off valve  62  should be turned to the “off” position until auxiliary fuel is required. When auxiliary fuel is required, the valve mechanism or shut off  62  is opened to provide auxiliary fuel through the regulator  58 . Again, check valve  86  precludes back flow of fuel into the tank or cylinder  20 . 
     With the present invention, the size of the spare or auxiliary fuel tank  26  is designed and provided to include, at least typically, more than about 2% of the volume of gas stored in the portable tank  20 . Preferably, approximately 8% to 10% of the fuel would be maintained in the auxiliary tank  26 . The auxiliary tank  26  also may include an indicator which indicates the amount of fuel retained therein and the pressure of the fuel. The spare tank  26  may be mounted on the inside of the upright, to further enhance the installation safety of the auxiliary tank system. The high pressure relief valve  64  need not necessarily be included in the outlet line of the tank  26 . It can be attached at some other outlet opening from the tank  26 . With the described system, down time previously allotted for portable tank  20  replacement is significantly reduced, resulting in operating cost savings and increased operating efficiency. 
     It is possible to vary the construction of the fuel tank system without departing from the spirit and scope of the invention. The system can be incorporated in other types of vehicles other than fork lift trucks. However, it is especially appropriate and useful in combination with a fork lift truck of the type using propane or natural gas as a fuel. Thus, while there has been set forth preferred embodiments of the invention, it is to be understood that the invention is limited only by the following claims and equivalents thereof.