Abstract:
The present invention is for a multi-combination vehicle including a prime mover having an engine and at least one powered trailer mechanically coupled to the prime mover. A control system measures the relative motion or force between the two, preferably by the use of a load cell and accordingly adjusts the operation of the engine on the power trailer so that the powered trailer and the prime mover are synchronized in their movement. This allows a multi-combination vehicle to carry a significant load, by providing sufficient motive power without the potential for damage to the transmission and differential system of the prime mover.

Description:
[0001]    The present invention relates to an over-the-road multi-combination vehicle where the power-to-weight ratio of the vehicle is maintained at an acceptable level through the use of an additional or secondary motive power source or engine to the one primary found in the vehicle and that is operatively coupled to the primary one.  
         BACKGROUND OF THE INVENTION  
         [0002]    Over-the-road multi-combination vehicles are well known and include a prime mover coupled to a plurality of trailers and converter dollies. Typically these vehicles have a single power source and are limited in gross combination mass to 200-230 tonnes.  
           [0003]    In some circumstances it is highly desirous that vehicles with greater tonnage and/or better control be used. To this end there have been several proposals of vehicles where there is an increase in its traction, including hydraulically driven axles and mechanically linked axles whilst using a single power source. Other proposals have included the use of a completely separate engine placed on the dolly. However, a satisfactory solution to the problem of matching the engine speeds of the prime mover and power dolly has not yet been proposed leading to the problem that the power dolly may jackknife and be difficult to control when braking.  
           [0004]    Multi-combination vehicles for dedicated road haulage tasks such as mineral concentrate haulage are currently operating at Gross Combination Mass (GCM) up to 230 tonnes. However, there is a practical limit to the GCM of the multi-combination vehicle with a single prime mover. The cost of haulage is determined mainly on weight. If one can therefore increase the total haulage that can be moved by a single prime mover that does not require additional operators, the cost benefit is substantial.  
           [0005]    It is an object of the present invention to overcome some of the abovementioned problems or to at least provide the public with a useful alternative by providing for a prime mover with two motive power sources.  
           [0006]    Accordingly the present invention discloses an additional motive power source for use with a prime mover, advantageously placed on a trailer and that is operatively coupled to the prime mover. The use of the electronically coupled power trailer maintains the power-to-weight ratio of the mover or vehicle at an acceptable level. This allows the vehicle to maintain sufficient road speed at GCMs well above the current practical limit for a single prime mover and hence improve the overall efficiency and productivity of the transportation system.  
         SUMMARY OF THE INVENTION  
         [0007]    Therefore in one aspect of the invention there is proposed a multi-combination vehicle including;  
           [0008]    a prime mover including a first power source located on said prime mover;  
           [0009]    a trailer mechanically coupled to said prime mover and including a second power source located on said trailer; and  
           [0010]    a control means adapted to operatively couple the first and second power sources.  
           [0011]    In a further aspect of the invention there is proposed a multi-combination vehicle including;  
           [0012]    a prime mover including a first power source located on said prime mover;  
           [0013]    a dolly mechanically coupled to said prime mover and including a second power source located on said dolly; and  
           [0014]    a control means adapted to couple the first and second power sources.  
           [0015]    In a yet further aspect of the invention a multi-combination vehicle includes:  
           [0016]    a prime mover including a plurality of wheels, at least some of the wheels caused to rotate by a first power source located on said prime mover to thereby move the prime mover at a first speed;  
           [0017]    a trailer mechanically coupled to said prime mover and including a plurality of trailer wheels wherein at least some of the trailer wheels are caused to rotate by a second power source located on said trailer to thereby move the trailer at a second speed; and  
           [0018]    at least one control means including at least one sensor to sense the motion of the prime mover and the trailer and effect a control of at least one of the power sources to thereby cause the motions of the prime mover and the trailer to be substantially the same.  
           [0019]    In preference the sensor is a load cell, and which senses the force exerted by the power trailer on the prime mover, the control means operatively controlling the second power source in response to that force, so that the load on the load cell is within a pre-determined range.  
           [0020]    In preference said vehicle includes a plurality of non-powered trailers, at least one said non-powered trailer mechanically coupled between said prime mover and said power trailer.  
           [0021]    In preference said vehicle includes a plurality of non-powered trailers, said non-powered trailers mechanically coupled to the power trailer.  
           [0022]    Preferably said multi-combination vehicle further includes a control system adapted to receive input from load cell operatively coupling the prime mover and the power trailer, and a plurality of sensors on both the prime mover and the power trailer, said sensors including engine management system sensors and driveline system sensors, said control systems operating said power trailer engine to synchronise the operation of the engines on the prime mover and the power trailer.  
           [0023]    Preferably said vehicle further includes hydraulic dampeners on said power trailer.  
           [0024]    Preferably said vehicle includes an articulation sensor and a control system that activates the hydraulic dampeners in response to the alignment of the power trailer to the prime mover to keep the alignment within a pre-determined range.  
           [0025]    The control systems accordingly operatively (by electronic means) couples the engine management system and the driveline control system of the prime mover to the engine management and driveline control system of the power trailer. The systems monitor the engine speed and gear on the power trailer to be automatically matched to the prime mover.  
           [0026]    In the event that the prime mover and power trailer are experiencing different sets of road conditions, which could cause the power trailer drive wheels to lose traction, a traction control system will automatically reduce the engine power output of the power trailer. Likewise if the prime mover has lost traction or the power trailer produces excessive load on the forward coupling the system will automatically reduce the engine power output of the power trailer.  
           [0027]    Since excessive tractive effort by the power trailer could cause interference with the forward trailer or trailers and could lead to the multi-combination vehicle becoming unstable, the control systems may also be adapted to sense of fore-aft load at the trailer coupling and control of the tractive effort at the power trailer. In the extreme event that the power trailer does become unstable, hydraulic actuators may be used to realign the power trailer with the forward trailer.  
       
    
    
     DESCRIPTION OF DRAWINGS  
       [0028]    To further assist in understanding the invention reference is made to the drawings in which like numerals are used to indicate like elements.  
         [0029]    [0029]FIG. 1 is a side elevation drawing of a multi-combination vehicle incorporating a power trailer according to the present invention;  
         [0030]    [0030]FIG. 2 is a perspective view of a power trailer;  
         [0031]    [0031]FIG. 3 is a side elevation drawing of a power trailer;  
         [0032]    [0032]FIG. 4 is a plan drawing of a power trailer;  
         [0033]    [0033]FIG. 5 is a front view of a power trailer; and  
         [0034]    [0034]FIG. 6 is a schematic plan of a control system operatively controlling the prime mover with the power trailer.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0035]    Turning now to the drawings in detail there is shown in FIG. 1 a multi-combination vehicle  10  including a prime mover  12  mechanically coupled to a plurality of trailers  14 . A power trailer  16  extends from forwardly located trailers  14  and a further trailer  14  is coupled to the power trailer  16 . A second power trailer  18  is coupled to the last trailer  14 . It is however to be understood that the multi-vehicle combination may be one or more power trailers, depending on the application.  
         [0036]    The prime mover  12  includes a chassis or frame  20  and a rear axle assembly  22 , which is suspended from and disposed below the chassis  18 . Forward axle  24  comprises the steering axle of the prime mover  12 . The rear axle assembly  22  is suspended from chassis  18  via an air suspension  26  and includes wheeled axles  28 . Both of the wheeled axles may be driving axles, or alternatively only one is a driving axle. The driving axles may be a tridem axle assembly in lieu of the tandem axle assembly  22  and possibly suspended with a mechanical suspension.  
         [0037]    The prime mover  12  further includes a motive power source  30  and a transmission (not shown) for transmitting torque from the motive power source  30  to the drive axles  28 . Typically the source of motive power comprises a diesel engine and the transmission for transmitting torque from the engine  30  to the drive axles  28  includes a gear box, a drive shaft and a differential (not shown). Alternatively, the source of the motive power  30  may comprise other types of internal combustion engines utilising a variety of fuels. As yet another alternative the source of motive power  30  may comprise an electric motor with the transmission transmitting torque comprising a suitable coupling interconnecting the electric motor and axle assembly  22 .  
         [0038]    The prime mover further includes a draw frame  32  attached to and rearwardly extending from the chassis  20 . A coupling  34  is attached to the rear of the draw frame and connected with a drawbar  36  on the trailer. A bin  38  accommodates payload to be carried by the prime mover and may be adapted to be side-tipping by hinge means (not shown) attached to the frame  20 .  
         [0039]    Each of the trailers  14 , and each of the power trailers  16  and  18 , includes a converter dolly  40  and a semi-trailer  42 , having a forward end with a coupling system  46  that pivotably attaches to a ball-race turntable  48  on the converter dolly. This enables the converter dolly to pivot relative to the semi-trailer about a generally vertical axis of rotation passing through the centre of the ball-race turntable. Other embodiments may however equally well be used, such as an oscillating ball-race turntable. The drawbar  36  is hingedly connected to the chassis  50  of the converter dolly  40  and accommodates for any change in the grade of the road surface. As with the prime mover, the trailer further includes a draw frame  32  attached and rearwardly extending from the chassis  52 . A coupling  34  is attached to the rear of the draw frame  32  and is connected with a drawbar  36  on the next trailer or power trailer. A bin  38  accommodates payload to be carried by the trailer and may be adapted to be side-tipping by hinge means (not shown) attached to the frame  52 .  
         [0040]    Referring to FIGS.  2 - 5 , the semi-trailer  42  of the power trailer  16  includes a chassis or frame  52  which may include a pair of longitudinally extending side members  54  and a plurality of transverse cross-members  56  interconnecting and attached to the side members  54 . The semi-trailer includes a rear axle assembly  58  that is suspended from chassis  52  by air suspension  60 . Alternatively the semi-trailer  42  may include a conventional mechanical spring assembly. The side members support or form part of the load carrying structure such as bin  38 . The load carrying structure may be a side tipping trailer, a stock crate, a fuel tank or any other type of structure for supporting a load. As with the prime mover and the trailer, the power trailer further includes a draw frame  32  attached and rearwardly extending from the chassis  52 . A coupling  34  is attached to the rear of the draw frame  32  and connected with a drawbar  36  on the next trailer or power trailer. A bin  38  accommodates payload to be carried by the power trailer and may be adapted to be side-tipping by hinge means (not shown) attached to the frame  52 .  
         [0041]    The rear axle wheel assembly  58  includes wheeled axles  62 . Extending above said wheeled axles are members  64  that may be used to support mudguards and the like (not shown). In an alternative the axle assembly may be a tandem assembly in lieu of the tridem axle assembly. The wheeled axles include a plurality of tires  66  mounted thereon for supporting the semi-trailer as it travels over a road surface.  
         [0042]    Mounted below the upper surface of the chassis  52  is a motive power source or engine  68  positioned generally centrally between the side members  54  and the chassis. A transmission (not shown) provides driving power from the engine to the axle assembly  58  where one or more of the wheeled axles  62  may be driven. The engine is typically a diesel engine and may advantageously include a turbocharger  70 . To be able to fit the engine in between the side members, the spatial distance between the two is generally larger than that conventionally found on existing semi-trailers. However, the standard width of the wheeled axles had to be kept the same to keep the vehicle roadworthy. This has necessitated mounting the suspension  60  under said side members rather than on their side.  
         [0043]    The engine  68  includes a radiator  72  to assist in cooling the engine through a typical fluid means. The turbocharger  70  includes an air cooling unit  74  that assist in cooling the air that is then injected into the engine. In a conventional cooling system the radiator and air cooler are mounted at the front of the vehicle, which is not possible in the power trailer. To achieve a sufficient flow through of air through the radiator  72  and air cooler  74  on the power trailer  14 , the radiator  72  and the air cooler  74  are positioned externally of said side members  54 , with the outer edge  76  of the radiator and air cooler not extending beyond the outer extent of the wheeled axles (seen clearly in FIG. 5). This provides protection for the radiator and the air cooler. Depending on the capacity of the engine, a minimum square area of the radiator and air cooler is required. Typically, each horse power of the engine requires around  10  square centimeters of radiator and air cooler area. To achieve this in the space provided both the radiator and the air cooler are positioned at an angle to the longitudinal axis of the side members  54 , the total angle depending on the size of the radiator and air cooler required for the size of the engine.  
         [0044]    The engine  68  on the power trailer is controlled by the control system  78  that is generally mounted in the cab  80  of the prime mover. A load cell  82  is located in the coupling system  46  that monitors a load in the longitudinal direction of the power trailer  16  and effects an output of that condition in the form of a electronic signal that is monitored by control system  78 . In the most simple form, the control system included a throttle control mechanism that controls the throttle of the engine on the power trailer and a transmission control mechanism that controls the engagement of the transmission to the drive axles. If the load cell indicates that the power trailer is exerting a large undesirable force on the prime mover, the control system reduces the throttle of the power trailer engine and thus the power on the power trailer. Conversely, if the load cell finds very little load, that is, the prime mover is essentially pulling the power trailer, the throttle is increased until the power motion of the power trailer is relatively self-propelling. During initial take-off, the control system directs the power trailer transmission to engage whilst increasing the throttle in line with that on the prime-mover.  
         [0045]    A more sophisticated control system may be employed. Referring to FIG. 6 the control system  78  thus may receive input signals from the prime mover engine control or management system (EMS)  84 , driveline control system  86 , the power trailer coupling load cell  82  and an articulation sensing device  88  discussed below. The input signals are processed electronically and generate output signals. The output signals from the control system  78  are operatively connected to the power trailer  16  and in particular to the power trailer engine management system  90 , driveline control system  92 , and a hydraulic actuation system  94  that controls hydraulic actuators  96 .  
         [0046]    As briefly mentioned above the power trailer  16  may further include a pair of hydraulic actuators  96  that can align the power trailer  16  in the event that it becomes unstable. A sensor (not shown) may be adapted to sense the articulation angle of the power trailer relative to the forward trailer or prime mover and effect a signal that is monitored by the control system  78  which activates, if necessary, according to pre-determined criteria, the actuators  96  to realign the power trailer.  
         [0047]    Thus one can see that the present invention teaches a multi-combination vehicle consisting of a powered prime mover, at least one powered trailer and which may include a number of non-powered trailers. The powered trailer is electronically coupled to the powered prime mover. By using one or a plurality of power trailers or secondary movers, that are electronically coupled to the prime mover, one may increase the gross combination mass. A control system ensures that the power trailer will not become unstable due to power jackknife. The control system electronically couples the Engine Management Systems (EMS) and Driveline Control System (DCS) of the power trailer and prime mover, may further incorporate traction control, may also monitor the forward coupling load and activate hydraulics to dampen any amplified yaw motion of the power trailer.  
         [0048]    By ensuring that the operation of the engines on the prime mover and the powered trailer are synchronised, the problems of take-off of a fully loaded vehicle are reduced, as is the potential damage to transmissions and differentials.  
         [0049]    Whilst the foregoing description has set forth the preferred embodiments of the present invention in some detail, it is to be understood that numerous modifications, obvious to a person skilled in the art, may be made without departing from the scope of the invention as defined by the ensuing Claims. It is therefore to be understood that the invention is not limited to the specific embodiments as herein described.