Abstract:
An ejector truck requires an ejector mechanism to remove hauled material from the ejector truck body. Often, these ejector mechanisms are costly and require precise manufacturing and maintenance because they include a telescoping linear actuator. The present invention provides a method and apparatus of a multi-actuator ejection mechanism. The multi-actuator ejection mechanism includes an anchor member, an ejection carriage, an ejector blade, a first linear actuator, and a second linear actuator. The ejector blade is located a predetermined distance from the anchor member and is adapted to move longitudinally with respect to the anchor member. The first linear actuator has a first end secured to the anchor member and a second end secured to the ejection carriage, and is adapted to move the ejection carriage longitudinally with respect to the anchor member. The second linear actuator has a first end secured to the ejection carriage and a second end secured to the ejector blade, and is adapted to move the ejector blade with respect to the ejection carriage. The multi-actuator ejection mechanism of the present invention uses multiple single-stage linear actuators instead of a single telescoping/multiple-stage linear actuator.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates to an ejection mechanism to remove hauled material from a hauling body and, more particularly, to such a mechanism which is actuated in multiple steps.  
         BACKGROUND  
         [0002]    Articulated trucks are commonly used in industry to haul material from one location and spread it in another location. Articulated trucks dump the hauled material either by tilting the body of the truck or by ejecting the material with a mechanized pusher/ejector blade. Ejector trucks are useful in many applications where a traditional tilting dump truck is undesirable or impractical. For instance, if there are power lines or a low bridge or other structure located above the worksite, the ejector truck can dump its load without contacting the overhead obstruction as would a tilting dump truck. Also, an ejector truck can spread the dumped material more easily and accurately than can a gravity-powered tilting dump truck, since the powered ejector blade gives the operator a great deal of control over the flow rate of the material.  
           [0003]    Ejecting the hauled material from the truck is currently accomplished using a multi-part telescoping hydraulic cylinder to push an ejector blade from the front of the body to the rear of the body in a known manner. These designs have worked well, but could be improved. The telescoping hydraulic cylinder is very expensive to manufacture, operate, and maintain. It requires a large amount of hydraulic fluid to fully extend, with all of the accompanying fluid supply and routing issues. The dimensions of, and clearances between, the telescoping sections must be very precise, and there are multiple sections needed to extend the cylinder to empty the truck totally, with each of those sections requiring meticulous machining and assembly. The cylinder will not function as desired if dirt, debris, or other hauled material spills over the ejector blade and scratches or dents the telescoping sections. Also, the extreme length of the extended telescoping cylinder makes it more likely to sag in the unsupported midsection. Over time, such sagging could bend the sections slightly, thus ruining the precise alignment of the sections.  
           [0004]    The present invention is directed to overcoming one or more of these complications by providing a method and apparatus of a multi-actuator ejection mechanism which: is protected from spillover material; uses common, simple components; includes intermediate support for the linear actuators; and is economical to manufacture and use.  
         SUMMARY OF THE INVENTION  
         [0005]    In an embodiment of the present invention, a multi-actuator ejection mechanism is provided. The multi-actuator ejection mechanism includes an anchor member, an ejection carriage, an ejector blade, a first linear actuator, and a second linear actuator. The ejector blade is located a predetermined distance from the anchor member and is adapted to move longitudinally with respect to the anchor member. The first linear actuator has a first end secured to the anchor member and a second end secured to the ejection carriage, and is adapted to move the ejection carriage longitudinally with respect to the anchor member. The second linear actuator has a first end secured to the ejection carriage and a second end secured to the ejector blade, and is adapted to move the ejector blade with respect to the ejection carriage.  
           [0006]    In an embodiment of the present invention, a method for providing a multi-actuator ejection mechanism to an ejector body is provided. The method includes the steps of extending a first linear actuator, moving an ejector carriage from a first carriage position to a second carriage position, moving an ejector blade from a first blade position to a second blade position, extending a second linear actuator, and moving the ejector blade from the second blade position to a third blade position.  
           [0007]    In an embodiment of the present invention, a multi-actuator ejector trailer is provided. The multi-actuator ejector trailer includes a trailer body, a ground-engaging device attached to trailer body and adapted to provide motive means to the trailer body, and an ejector mechanism attached to a forward portion of the trailer body. The ejector mechanism includes an ejector blade, an anchor member, an ejector carriage, a first linear actuator, and a second linear actuator. The ejector blade is located on top of the trailer body and is adapted to move from the forward portion of the trailer body to a rearward portion of the trailer body. The anchor member is located forward of the ejector blade and is substantially fixed in position. The ejector carriage is located between the ejector blade and the anchor member and adapted to move from a forward position near the anchor member to a rearward position near the ejector blade. The first linear actuator is located between the anchor member and the ejector carriage, attached to the anchor member and the ejector carriage, and operative to move the ejector carriage with respect to the anchor member. The second linear actuator is located between the ejector carriage and the ejector blade, attached to the ejector carriage and the ejector blade, and operative to move the ejector blade with respect to the ejector carriage. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a perspective view of an ejector trailer according to the present invention.  
         [0009]    [0009]FIG. 2 is a perspective view of a multi-actuator ejection mechanism according to the present invention situated in a fully retracted position.  
         [0010]    [0010]FIG. 3 is a perspective view of a multi-actuator ejection mechanism according to the present invention situated in a fully extended position.  
         [0011]    [0011]FIG. 4 is a flow chart showing the operating sequence of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0012]    A preferred embodiment of the present invention provides an apparatus and method of a multi-actuator ejection mechanism. The following description uses an articulated truck as an example only. This invention may be applied to other types of work machines, either installed as a part of the work machine or as a separate entity in some sort of towed or pushed arrangement with an articulated truck, a wheeled tractor, a track-type tractor, a belted tractor, or any other suitable work machine or machine body.  
         [0013]    [0013]FIG. 1 depicts an ejector trailer  100  according to the present invention. The trailer comprises a trailer body  102 , a pair of ground-engaging devices  104  supporting the trailer body  102 , and a multi-actuator ejection mechanism, shown generally at  106 . The ground-engaging devices  104  may be pneumatic tires as illustrated but may be any other suitable structure such as the rubber-belted undercarriage available from Caterpillar Inc. under the brand name Mobil-trac™.  
         [0014]    The trailer body  102  shown in FIG. 1 is typical of the type of hauling bed or body with which the present invention can be utilized. A typical hauling body has two opposing sides and a bottom having a first bottom end and a second bottom end spaced longitudinally from the first bottom end. The multi-actuator ejection mechanism  106  of the present invention may be used with any suitable body used to haul material, whether that body is mounted on or pulled behind a truck, pushed ahead of a truck, or any other suitable arrangement, without departing from the spirit and scope of the present invention.  
         [0015]    The multi-actuator ejection mechanism  106  is shown in FIGS. 1, 2, and  3 , and comprises an anchor member  108 , an ejector blade  110 , an ejection carriage  112 , a first linear actuator  300  (FIG. 3), and a second linear actuator  114 . The anchor member  108  is an anchor in the sense of providing a fixed point with respect to which other components of the multi-actuator ejection mechanism move or by which other components are supported. The first linear actuator  300  connects the anchor member  108  and the ejection carriage  112 . The second linear actuator  114  connects the ejection carriage  112  and the ejector blade  110 . The linear actuators are preferably extendible and may be a hydraulic cylinder, pneumatic piston device, telescoping “multi-stage” cylinder, or the like.  
         [0016]    The multi-actuator ejection mechanism  106  may include an ejection track  116  having a first track end  118  connected to the anchor member and a second track end  120  spaced longitudinally from the first track end  118 . Should the multi-actuator ejection mechanism  106  include such an ejection track  116 , the ejection carriage  112  will be adapted to move along the ejection track  116 . By “move along”, what is meant is that the ejection carriage  112  is preferably guided by the ejection track  116  and may be supported by the ejection track  116 , and the ejection carriage  112  moves in a controllable manner between the first track end  118  and the second track end  120 . This motion may be done in a sliding, rolling, ratcheting, or other suitable manner, as the exact type of motion is not essential to the present invention. Optionally, the supporting or guiding functions could be accomplished by another suitable structure without departing from the spirit of the present invention.  
         [0017]    The first and second linear actuators  300 ,  114  may be single- or multi-stage hydraulic cylinders. It would then be desirable for a power provider (not shown) to supply pressurized hydraulic fluid to the first and second linear actuators  300 ,  114  in order to extend or retract the first and second linear actuators  300 ,  114  in a known manner.  
         [0018]    The first linear actuator  300  may be substantially enclosed by a first piston shroud system  122 . The first piston shroud system  122  comprises an inner tube  124  substantially surrounding the first piston  300  when the multi-actuator ejection mechanism  106  is in a retracted position, and an outer tube  126  substantially surrounding the inner tube  124  when the multi-actuator ejection mechanism  106  is in a retracted position. The inner tube  124  and outer tube  126  are able to be moved in a telescoping manner with respect to one another and to the first piston  300 . Such motion is mainly in a longitudinal direction. The inner tube  124  may be secured to one of the anchor member  108  and the ejection carriage  112 , and the outer tube  126  may be secured to the other of the anchor member  108  and the ejection carriage  112 , to facilitate the relative telescopic motion of the inner tube  124  and the outer tube  126 .  
         [0019]    While aspects of the present invention have been particularly shown and described with reference to the preferred embodiment above, it will be understood by those skilled in the art that various additional embodiments may be contemplated without departing from the spirit and scope of the present invention. For example, the linear actuators could be controlled or powered in a different manner, there could be additional coupling mechanisms than those described, or the configuration of the ejector truck and trailer could be different. However, a device or method incorporating such an embodiment should be understood to fall within the scope of the present invention as determined based upon the claims below and any equivalents thereof.  
         [0020]    Industrial Applicability  
         [0021]    In the field, the present invention will be utilized much as the prior art ejector trucks. That is, an operator will control the movement of the ejector blade to push the hauled material out of the trailer body in a desired manner. However, in lieu of the single lengthy multiple-section telescoping hydraulic cylinder taught by the prior art, the present invention uses a multi-actuator ejection mechanism  106  as described above.  
         [0022]    When the multi-actuator ejection mechanism  106  is in a fully retracted position, the ejector blade  110  is located in a first blade position toward a forward portion of the trailer body  102 . The ejector trailer  100  can be loaded and moved in a known manner. When the operator wishes to eject the hauled material from the trailer body  102 , he may either manually (as with a modulated lever or the like) or automatically (as with a push-button or the like) control the ejector function as described below and as shown in FIG. 4. The ejector trailer  100  can be stationary or moving as the ejector function runs. The ejector function may be interrupted, reversed, or stopped before it runs completely with no ill effect on the present invention. If the ejector trailer  100  is towed behind a work machine or an other ejector trailer  100  which hauls material as well and which may also be equipped with a prior art ejection mechanism and/or a multi-actuator ejection mechanism  106  according to the present invention, the rearmost ejector trailer  100  is preferably, but not necessarily, at least partially ejected before the other work machine or ejector trailer  100  is ejected/unloaded. This rear-first sequencing can provide advantages in power routing which are discussed below.  
         [0023]    The ejector function uses a multi-actuator ejection mechanism  106  as described above. When the operator indicates that the ejector blade  110  is to push the hauled material out of the trailer body  102 , a signal is sent at first block  400  (FIG. 4) which prompts the first linear actuator  300  to extend. Preferably, a power provider  402  provides actuating power to the first linear actuator at second block  404 . This extension pushes the ejection carriage  112  away from the anchor member  108 , moving the ejection carriage  112  from a first carriage position to a second carriage position at third block  406 . The extension of the first linear actuator  300  also moves the ejection carriage  112  along the ejection track  116 , should one be provided. If a first piston shroud system  122  is provided, the inner tube  124  and the outer tube  126  are moved one relative to the other in a telescoping fashion by the extension of the first linear actuator  300 , as well. Since the ejection carriage  112  is connected to the ejector blade  110  via the (retracted) second linear actuator  114 , the ejector blade  110  moves from a first, or fully retracted, blade position to a second blade position through the extension of the first linear actuator  300  as shown at fourth block  408 .  
         [0024]    Either simultaneously with, before, or after the extension of the first linear actuator  300 , the second linear actuator  114  extends. Actuating power for the second linear actuator  114  may also be provided by the power provider and is not shown separately in FIG. 4. Since the second linear actuator  114  connects the ejection carriage  112  and the ejector blade  110 , the extension of the second linear actuator  114  moves the ejector blade  110  away from the ejection carriage  112  and from a second blade position to a third, or fully extended, blade position at fifth block  410 . FIG. 4 depicts fifth block  410  occurring after fourth block  408 , but this placement is merely for ease of depiction and the fifth block  410  may occur at any suitable timing. The multi-actuator ejection mechanism  106  and the trailer body  102  should be sized and arranged such that movement of the ejector blade  110  to the third blade position—that is, fully extending the multi-actuator ejection mechanism  106 —pushes the hauled material out of the trailer body  102 , substantially emptying the trailer body  102 . At this point, the ejector function has been completed.  
         [0025]    The first, second, and third blade positions, and the first and second carriage positions, are not absolute, but depend upon the timing of the actuation of the first and second linear actuators  300 ,  114 . The ejector blade  110  and ejection carriage  112  need not hesitate or stop at any of these positions, but may, instead, move fluidly therebetween. These blade and carriage positions are not essential to the present invention, but are provided as a guide to understanding the motion of the ejector blade  110  and ejection carriage  112 , where the first blade position corresponds to the multi-actuator ejection mechanism  106  being fully retracted and the third blade position corresponds to the multi-actuator ejection mechanism  106  being fully extended.  
         [0026]    Once the multi-actuator ejection mechanism  106  is fully extended, it must then be retracted to allow the trailer body  102  to be again filled with hauled material. To retract the multi-actuator ejection mechanism  106 , the first and second linear actuators  300 ,  114  are retracted in any suitable order or simultaneously to effectively reverse the movements of the ejection carriage  112  and the ejector blade  110  as described above.  
         [0027]    It is intuitively obvious that the present invention does not limit a multi-actuator ejection mechanism  106  to having only one ejector carriage  112  and first and second linear actuators  300 ,  114 . In fact, one skilled in the art would be able to readily fabricate a multi-actuator ejection mechanism  106  having multiple ejector carriages  112  and additional linear actuators located as needed to provide a longer ejector blade travel distance than that shown and described herein, including a fourth blade position at the new extent of ejector blade travel. These multiple ejector carriages  112  and additional linear actuators may operate simultaneously or in any suitable order relative one to another. Such a system would be particularly advantageous when used on an ejector truck or a towed ejector trailer  100  having a longer trailer body  102  than the ejector trailer  100  shown in the Figs. The operation of such an arrangement is shown by a dotted line in FIG. 4, where the first and second carriage positions and first, second, and third blade positions should each be construed relative to the multiple ejector carriages  112  and additional linear actuators being actuated at that time.  
         [0028]    In operation, an ejector trailer  100  according to the present invention is attached to a hitch, tongue, or other suitable member (as shown in FIG. 1) and pulled behind a truck cab or another ejector trailer  100 , such pulling device being with or without a multi-actuator ejection mechanism  106  according to the present invention installed thereon as needed. In addition, the multi-actuator ejection mechanism  106  can be installed as a retrofit feature on any suitable prior art articulated truck or ejector truck. Though the ejector trailer  100  could include a power source integrally, the power source normally is provided by the truck cab pulling the ejector trailer(s)  100 . Should the power source be hydraulic and the ejector trailer  100  including a multi-actuator ejection mechanism  106  be pulled by another ejector trailer  100 , greater efficiency can be provided by allowing a return hydraulic pressure from the retracting first and second linear actuators  300 ,  114  to provide power to the pulling ejector trailer  100 .  
         [0029]    The steps of operation described above for the multi-actuator ejection mechanism  106  may be performed in any workable order to eject material from an ejector trailer  100  or other hauling body. Preferably but not necessarily, the first linear actuator  300  is actuated before the second linear actuator  114 , which may provide power supply and routing efficiencies.  
         [0030]    The apparatus and method of certain embodiments of the present invention protect the invention from spillover material, use common, simple components, include intermediate support for the linear actuators, and are economical to manufacture and use. In addition, the present invention may provide other features that have not yet been discovered.  
         [0031]    It should be understood that while a preferred embodiment is described in connection with an articulated truck or ejector truck, the present invention is readily adaptable to provide similar functions for other work machines. Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.