Abstract:
The invention is a truck chassis offering design flexibility in a vehicle cab by mounting the engine between front and rear wheel assemblies. The present invention provides superior engine-weight distribution, handling, cab occupancy space, and cost effectiveness, while not lowering vehicle ground clearance. The present invention provides a truck chassis frame having front and rear wheel assemblies, a cab attached to a forward region of the chassis frame, and a powertrain having an engine mounted between front and rear wheel assemblies at a position that an engine top extends no more than 10 percent of its overall height above the chassis frame. This is particularly important in configurations wherein the engine top is under the cab. Other design features allow engine cooling systems that significantly reduce or even eliminate an engine tunnel housing in the vehicle cab.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to a provisional patent application serial number 60/272,229 titled, “An Improved Fire Truck Chassis Configuration,” filed Feb. 28, 2001. The entire disclosure of serial number 60/272,229 is incorporated herein by reference in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a heavy vehicle chassis configuration and more particularly to a cost-effective and efficient mid-engine chassis powertrain configuration suitable for use in a fire truck.  
           [0004]    2. Background and Description of the Prior Art  
           [0005]    Fire trucks are often considered “heavy” vehicles typically referring to their weight of more than 10,000 pounds. These vehicles usually have an engine mounted forward of the front axle or front suspension. A heavy vehicle chassis typically houses mechanical workings such as suspension, powertrain, steering, braking, and cooling systems. Overall vehicle construction typically includes a chassis, a superstructure, and a cab (or body). See generally, U.S. Pat. No. 5,863,070 to Williams, et al., and U.S. Pat. No.  5 , 314 , 205  to Glesmann.  
           [0006]    Heavy vehicles, not surprisingly, often require heavy engines to propel them. Front and rear mounted engines can create a vehicle with uneven weight distribution. Front-end engine placement (i.e., mounted ahead of a front axle or front suspension) creates a large engine housing that extends into the vehicle cab and subjects occupants to excessive engine heat and noise. This housing often covers part of an engine tunnel (or channel) used to direct airflow past a heat exchanger. The tunnel and corresponding housing within the cab also significantly reduce driver and passenger space in the front of the vehicle. Nevertheless, a vehicle designer is forced to restrict space in the vehicle cab to accommodate the engine housing and tunnel.  
           [0007]    Rear-end engine placement configurations in trucks (i.e., engine is mounted behind the rear axle) are known in the art as a way to reduce engine noise, space and heat in the vehicle cab as described above. See generally, U.S. Pat. No. 4,811,804 to Ewers et al. This design achieves these goals but at great expense and loss of much of the rearward usable chassis space.  
           [0008]    Mid-engine truck chassis configurations are also known in the art including fire trucks. For example, U.S. Pat. No. 4,059,170 to Young claims a mid-engine chassis design as a means to improve vehicle handling and safety by significantly reducing the load to the front tires. Mid-engine placement in a heavy fire truck chassis has been referred to in the art as a Spartan Motor Baron-type configuration. The mid-engine configuration allows more design flexibility and conveniences but is expensive since specialized and complicated cooling systems need to be adapted for such a configuration.  
           [0009]    Thus, there is a desire and need for a heavy vehicle chassis that not only improves vehicle cab occupancy space, weight distribution, handling, and design flexibility, but also accomplishes these objects in a manner that is cost-effective and efficient.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, the present invention provides a truck chassis configuration. Overall, engine placement in the chassis configuration of the present invention allows sufficient ground clearance, reduces overall engine noise within the cab, provides easy access for maintenance, improves handling and maneuverability, and simplifies engine cooling systems. The engine placement is also cost-effective, while not raising the vehicle&#39;s overall center of gravity or significantly increasing vehicle cost.  
           [0011]    The invention is a truck with a chassis frame having at least two chassis frame rails having a forward region and a rearward region, at least one intermediate cross member connecting the frame rails, a forward wheel assembly comprising at least two front wheels, a forward axle, and a forward suspension assembly attached to the chassis frame rails, and a rearward wheel assembly comprising at least two rearward wheels, at least one rearward axle, and rearward suspension assembly attached to the chassis frame rails. The invention is a truck with a powertrain comprising an engine, transmission and drive-shaft mounted to at least one wheel assembly positioned between and attached to the chassis frame rails between the front wheel assembly and the rearward wheel assembly and being at a position that the engine top extends no more than 10 percent of an overall engine height above the chassis frame rails.  
           [0012]    The invention can have a engine or powertrain cooling system disposed between the chassis frame rails that can have a heat exchanger, a fan (mechanical or hydrostatic), an engine tunnel configured to extend no more than 24 inches (61 cm) in height above the chassis frame rail at its highest point and extending above the chassis frame rails no more than 38 inches (97 cm) in length, the engine tunnel width defined by a dimension separating the chassis frame rails, and a coolant flow path connecting the engine and the heat exchanger. The heat exchanger can be located at the front or rear of the engine tunnel or anywhere in between.  
           [0013]    In one embodiment of the present invention, the heat exchanger can be non-vertical, including horizontal. In this embodiment, the need for an engine tunnel is significantly reduced or even eliminated.  
           [0014]    The present invention can also have a cab attached to and above a forward region of the chassis frame comprising a cab floor and a cab floor inclined front section, the cab floor inclined front section configured to conform to the dimensions of the engine tunnel.  
           [0015]    Other objects of the present invention will become more apparent to persons having ordinary skill in the art to which the present invention pertains from the following description taken in conjunction with the accompanying figures. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0016]    The foregoing objects, advantages, and features, as well as other objects and advantages, will become apparent with reference to the description and drawings below, in which like numerals represent like elements and in which:  
         [0017]    [0017]FIG. 1 illustrates a side view of one embodiment of the present invention.  
         [0018]    [0018]FIG. 2 illustrates a top view of one embodiment of the present invention.  
         [0019]    [0019]FIG. 3 illustrates a perspective view of the present invention with the hinged cab raised to expose the chassis.  
         [0020]    [0020]FIG. 4 illustrates an alternate embodiment of the present invention having a non-vertical heat exchanger.  
         [0021]    [0021]FIG. 5 illustrates an alternate embodiment of the present invention showing the heat exchanger moved closer to the fan. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    The present invention generally relates to a truck chassis powertrain configuration. FIGS. 1, 2 and  3  illustrate side, top, and perspective views, respectively, of one embodiment of the present invention. In this embodiment, a truck chassis generally indicated at  20  is illustrated having a chassis frame  22  having at least two frame rails. The chassis  20  has a forward region  24  (generally the forward half of the chassis  20 ) and a rearward region  26  (generally the rearward half of the chassis  20 ) and can generally be used as a fire truck chassis.  
         [0023]    The chassis frame  22  begins at the forward region  24  at a point beyond a forward wheel assembly  30 . The forward wheel assembly  30  has at least two front wheels  28  (which can be steerable), at least one forward axle  31  and a forward suspension assembly  33  attached to the chassis frame  22  rails. The forward wheel assembly  30  is attached to the forward region  24  of the chassis  20 . The chassis frame  22  runs rearward to the rearward region  26  of the chassis  20  to a point beyond a rearward wheel assembly  34 . The rearward wheel assembly  34  has at least two rear wheels  32 , at least one rearward axle  35  and a rearward suspension assembly  37  attached to the chassis frame  22  rails at the rearward region  26  of the chassis  20 . The rearward wheel assembly  34  can also be configured to be steerable (not shown). The distance beyond which the chassis frame  22  extends past the wheel assemblies  30  and  34  is dictated by good engineering principles which, in turn, are governed by the length, gross vehicle weight and suspension requirements of a s 15  particular vehicle. The same is true for the number of axles on each wheel assembly  30  and  34 . The present embodiment for simplicity uses only one axle per wheel assembly (forward  30  and rearward  34 ).  
         [0024]    The chassis frame  22  is preferably made of steel and can be approximately eight to ten inches (25 cm) in height. At least one intermediate cross member  36  can lay perpendicular to and affixes to, thus connecting, the chassis frame  22  rails at predetermined points and are cut to a length to define a width of the chassis frame  22 . The intermediate cross member  36  adds strength to the chassis  20 . The width of the chassis  20  is a distance governed by the engineering needs of the particular vehicle. These needs can include the space needed to house a powertrain and an engine (or powertrain) cooling system (“cooling system”)  50  as described below.  
         [0025]    The powertrain can have an engine  40 , a transmission  42 , and a driveshaft  44 . The transmission  42  can be attached to the engine  40  and the driveshaft  44  can be attached to the transmission  42 . In the illustrated embodiment, the driveshaft  44  is attached to the rearward wheel assembly  34  through the rearward axle  35 .  
         [0026]    The cooling system  50  has a heat exchanger  58 , a fan  56 , an engine tunnel  46 , and a coolant flow path  60 . The coolant flow path  60  connects the engine  40  and heat exchanger  58 . In the embodiment illustrated in FIGS. 1, 2, and  3 , the heat exchanger  58  is vertical and disposed in the forward end of the engine tunnel  46 . The heat exchanger  58  can also be disposed at the rear end of the engine tunnel  46 . The present invention can use a mechanical or hydrostatic fan  56  drive whereby the entire cooling system  50  is confined between the chassis frame  22  rails.  
         [0027]    The engine tunnel  46  can be configured to extend no more than 24 inches (61 cm) in height above the chassis frame rail at its highest point and extending above the chassis frame rails no more than 38 inches (97 cm) in length, the engine tunnel  46  width defined by a dimension separating the chassis frame rails. These dimensions are greatly reduced over the prior art.  
         [0028]    The chassis frame  22  can also house a steering unit  52  and braking systems  54 . These are well known in the art. Other powertrain configurations are also possible such as front wheels  28  or all wheel drives. In the embodiment shown in FIGS. 1, 2 and  3 , the transmission  42  and driveshaft  44  are coupled to the rear wheels  32 . Thus, the rearward wheel assembly  34  has the drive wheels. Alternatively, the vehicle could be configured to couple a powertrain to the forward wheel assembly  30  by mounting the engine  40 , transmission  42 , and driveshaft  44  at 180 degrees to the configuration shown, or in any of a number of other positions known in the art to facilitate the front wheel  28  drive configuration. Thus, the drive wheels would be within the forward wheel assembly  30 . The driveshaft  44  can also be mounted to at least one wheel assembly  30  or  34 .  
         [0029]    The configuration illustrated in FIGS. 1, 2 and  3  shows the engine  40  positioned just behind the forward wheel assembly  30 . This configuration distributes more engine  40  weight to the rearward wheel assembly  34  to give improved chassis  20  weight distribution over a conventional forward mounted engine  40  configuration. Further, it eliminates the need for a large engine tunnel  46  as is known in the art. The present invention can be configured to position the engine  40 , transmission  42  and driveshaft  44  anywhere between and attached to two chassis frame  22  rails between the forward wheel assembly  30  and the rearward wheel assembly  34 .  
         [0030]    A noted improvement in the present invention over the prior art mid-engine chassis  20  configuration is the ability to use the conventional engine  40  such as a 6-cylinder Cummins, Inc. ISB 300HP. Other conventional engines  40  could be used such as those supplied by Caterpillar, Inc. The present invention also eliminates the need to use more expensive  40  cooling systems  50  as used in the art (such as is found in the Spartan Motor Baron mid-engine configuration). This is due in part to the cooling system  50  remaining within the chassis frame  22  as opposed to side mounting in the prior art.  
         [0031]    The present invention mounts the conventional engine  40  as shown in FIG. 1 to allow only a minimal amount of the engine  40  to extend above the chassis frame  22  as found in the prior art. Specifically, as shown in FIG. 1, the engine  40  is positioned so that at most only about ten percent of the overall engine  40  height needs to extend above a top of the chassis frame  22  rails.  
         [0032]    Overall, the engine  40  placement as found in the illustrated embodiments allows sufficient engine  40  bottom ground clearance that is not lowered to unsafe levels, reduces overall engine  40  noise within a cab (see below), provides easy access for maintenance, improves handling and maneuverability, and simplifies cooling systems, while not raising the vehicle&#39;s overall center of gravity or significantly increasing vehicle cost.  
         [0033]    As illustrated, the chassis frame  22  also allows for efficient and cost effective engine  40  or powertrain cooling and cab designs. FIGS. 1, 2 and  3  and show one vehicle cooling system  50  configuration of the present invention. The present invention allows a simple cooling system  50  configuration well known in the art despite the location of the engine  40 . Further the cooling system  50  is predominately confined to within the chassis frame  22 . The engine tunnel  46  of the present invention minimally extends into a vehicle cab  48  beginning at or near a cab front  70  and attached to and above the forward region  24  of the chassis frame  22 . For example, in the embodiment illustrated in FIGS. 1 through 3, the vehicle cab  48  can have a cab floor  76  and the cab front  70 . The cab floor  76  can have a cab floor inclined front section  80  to conform to the shape and dimensions of the engine tunnel  46  (described above). As shown in FIG. 3, the vehicle cab  48  can have a cab hinge  110 . The cab hinge  110  allows access to chassis  20  components by raising the vehicle cab  48  up and away from the chassis  20  as illustrated. This cab hinge  110  mechanism is well known in the art.  
         [0034]    As illustrated in the embodiment of FIGS. 1, 2 and  3 , the cab floor inclined front section  80  of the engine tunnel  46  can be configured to extend from the cab front  70  rearward to a first dimension  72  of no more than thirty-eight inches (38″) (97 cm) in length and extend upward from the lowest part of the cab floor  76  to a second dimension  74  of no more than twenty-four inches (24″) (61 cm) in height above the chassis frame  22  rail into the vehicle cab  48  at its highest point. A third dimension  78 , shown in FIG. 2, is the width of the cab floor inclined front section  80 . This third dimension  78 , (as well as and the engine tunnel  46  width) is defined by and can be configured to conform to the width of the chassis frame  22 . Again, these dimensions are greatly reduced over the prior art.  
         [0035]    Other possible embodiments could also allow for a side-mounted or non-vertical mounted heat exchanger  58  or the rear-mounted engine tunnel  46  as part of the cooling system  50 . For side mounted cooling systems, the system would be mounted near the engine  40  but outside of the chassis frame  22  (not shown).  
         [0036]    [0036]FIG. 4 illustrates an embodiment of the present invention configured with a non-vertical mounted heat exchanger  58 . As shown, a horizontal heat exchanger  100  (such as a radiator), a horizontal fan  102 , and a horizontal coolant loop  104  are mounted within the confines of the chassis frame  22 . In this configuration, the cab floor  76  can be configured to have essentially a flat floor space. In this configuration, the first dimension  72 , second dimension  74 , and third dimension  78  are reduced or even eliminated. In other words, the cab floor inclined front section  80  is removed. This allows greater design flexibility for inclusion of passengers and equipment over the other embodiments using the vertically mounted heat exchangers.  
         [0037]    [0037]FIG. 5 adds one more illustration of an embodiment of the present invention with a vertical heat exchanger  58  located at the engine  40  side of the engine tunnel  46 . The present invention allows flexibility to place the heat exchanger  58  anywhere within the engine tunnel  46 .  
         [0038]    The above description is that of just one embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as set forth in the claims. The embodiment of the invention in which exclusive property or privileges claimed are defined as follows.