Abstract:
A hood raising apparatus for a hood of a vehicle of the type having a frame and at least one fluid powered actuator coupled to the hood and the frame, and a circuit in communication with the actuator and structured and arranged to control the actuator for raising or lowering the hood.

Description:
TECHNICAL FIELD  
       [0001]     The present invention is directed to a hood positioning apparatus and method and, more specifically, a hood positioning apparatus and method thereof for raising or lowering hoods that may be impracticable to raise or lower manually.  
       BACKGROUND  
       [0002]     In general, vehicles are provided with compartments such as engine compartments which are typically used in conjunction with hoods which, in turn, are used to at least partially cover the compartment and to protect the contents of the compartment such as the engine and supporting componentry from dust, debris, weather, theft, etc. Engine compartments may also be covered to contain noise and route cooling air flow. Such compartments are generally kept covered by hoods in normal use of the vehicle and in storage, but must be opened to provide access for periodic maintenance and inspection and for repairs. However, engine compartment hoods of work vehicles such as wheeloaders, tractors, and the like, are typically large and very heavy and can require significant reach and effort to manually open and close.  
         [0003]     There have been prior art attempts to provide some form of mechanical assist in moving hoods. One such example can be found in U.S. Pat. No. 6,167,977 which issued on Jan. 2, 2001, to Adamson et al. which teaches the use of gas struts to provide a biasing force to assist in raising the hood. Although adequate for its intended purpose of assisting in raising the hood, this design does not provide assistance in thereafter lowering the hood. Furthermore, these devices may be limited in the amount of biasing force they can generate thereby making them impracticable for very heavy hoods.  
         [0004]     The present invention is directed to overcoming one or more of the problems as set forth above.  
       SUMMARY OF THE INVENTION  
       [0005]     In accordance with an embodiment of the present invention, a hood raising apparatus for a hood of a vehicle of the type having a frame is provided and comprises at least one fluid powered actuator coupled to the hood and the frame; and a circuit in communication with the actuator and structured and arranged to control the actuator.  
         [0006]     In accordance with another embodiment of the present invention, a method of positioning a hood of a vehicle, of the type having a frame, is provided comprising the steps of providing at least one fluid powered actuator coupled to the hood and the frame, and providing a circuit coupled to the fluid powered actuator and structured and arranged to control the actuator to perform at least one of raise and lower of the hood. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is an elevation view of a vehicle incorporating an embodiment of a hood positioning apparatus of the present invention; and  
         [0008]      FIG. 2  is diagrammatical view of an embodiment of a circuit used with the hood positioning apparatus of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0009]     With reference to the Figures, shown in  FIG. 1  is a vehicle  100 , embodied herein for exemplary purposes by a wheel loader-type work machine, incorporating the hood positioning apparatus  101  of the present invention. For exemplary purposes, those relevant portions of the vehicle  100  useful or necessary to fully describe the present invention will be discussed herein. Shown is the vehicle  100  having a frame  104  used to support a prime mover or engine  105 . Pivotally coupled to the frame  104  at attachment point  106  is a hood  108 , having a center of gravity  109 , that is shown in the raised position and that is used to house the engine  105 . A pair of actuators each embodied herein by a hydraulic cylinder  112  (one shown) couple the hood  108  to each side of the frame  104 . In view of the fact that each hydraulic cylinder  112  is substantially the same and used in substantially the same manner, only one hydraulic cylinder  112  will be referenced herein. For purposes of illustration and not limitation, each hydraulic cylinder  112  comprises a double-acting hydraulic cylinder having a cap end  113  coupled to the frame  104  and a rod end  116  coupled to the hood  108  at a pivotal attachment point  117 .  
         [0010]     With reference to  FIG. 2 , an embodiment of the circuit  200  used to control the hood positioning apparatus  101  of the present invention will now be described. For purposes of clarification, solid lines shown in  FIG. 2  represent fluid channels and solid lines with the double hash marks shall represent electrical channels. As shown, the circuit  200  comprises a hydraulic portion  201  that includes a reservoir  204  used to store hydraulic fluid. A pump  205 , driven by motor  208 , draws fluid from the reservoir  204  in a known manner. A filter  212  may be provided to prevent potentially damaging particulates from entering the pump  205 . A first hydraulic line  213  is coupled to the rod end  116  of the hydraulic cylinder  112 , and a second hydraulic line  216  is coupled to the cap end  113  of the hydraulic cylinder  112 . Upon exiting the pump  205 , fluid travels through a flow prevention device or check valve  217  and passes through a directional control valve  220 , having a moveable spool  221 , and may either continue to pass though the first hydraulic line  213  or be diverted to the second hydraulic line  216  depending on the whether the circuit  200  has been orientated to raise or lower the hood  108 .  
         [0011]     If the fluid is oriented to continue through the first hydraulic line  213 , prior to entering the rod end  116  of the hydraulic cylinder  112 , fluid flow passes through a first flow control device  222  which comprises a flow metering portion  223 , having a first flow control characteristic, and having an flow prevention portion  226  that is embodied herein by a check valve. In the event that flow is diverted to the second hydraulic line  216 , fluid passes though a flow prevention device embodied herein by a pilot operated check valve  227 , having a pilot pressure line  228  for communicating a source of pressure to the pilot operated check valve  227 , and then through a second flow control device  230  prior to reaching the cap end  113  of the hydraulic cylinder  112 . The second flow control device  230  also comprises a flow metering portion  231 , having a second flow control characteristic, and a flow prevention portion  234  that is also embodied herein by a check valve. For exemplary purposes only, the first and second flow control devices  222 , 230  are embodied herein by pressure-compensated flow control valves. However, any device capable of exhibiting one or more of flow metering and flow prevention characteristics is contemplated to be within the scope of the present invention.  
         [0012]     As used herein, the term “flow control characteristic” refers to the rate of flow allowed through a respective flow control device. In an embodiment of the present invention the second flow control device  230  has a second fluid flow characteristic that is greater than the first flow characteristic of the first flow control device  222  with each respective flow characteristics chosen to allow the hood  108  to raise and lower at approximately the same rate. As should be appreciated by those of ordinary skill in such art, the flow characteristics of the flow metering portions  223 ,  231  may be optimized or otherwise adjusted to provide the desired rate of ascent of descent of the hood  108 . Furthermore, as should be apparent to those of ordinary skill in such art, the provision of each of the respective flow control device  222 , 230  provide for free or unregulated flow in each respective hydraulic line  213 ,  216  when the fluid flow is in the direction of arrow  235 , and provides for regulated or metered flow through the respective flow metering portions  223 , 231  when the fluid flow is in the direction of arrow  238 . In the event excess pressure develops in the hydraulic portion  201 , a relief valve  239  is provided to bleed off the excess pressure in a known manner.  
         [0013]     With further reference to  FIG. 2 , the electrical portion  242  of the circuit  200  will now be described. Energy is provided to the motor  208  by means of a power source comprising in an embodiment of the present invention a battery  243 . A switching device  246 , which may comprise a toggle switch or other like activation device, is provided and is manipulated in a known manner to raise, lower or hold the position of hood  108  in a desired location. For the exemplary circuit  200  illustrated and described herein, placing the switching device  246  in the raise or first position denoted  247  will result in the raising of the hood  108 . Placing the switching device  246  in the lower or second position denoted  250  will result in the lowering of the hood  108 ; and placing the switching device  246  in the neutral or third position denoted  251  will result in the hood  108  being maintained in the then current position. In the event of a failure of the electrical portion  242  of the circuit  200 , a backup power device such as a manual pumping device  254  is provided to move the hood  108  in a known manner.  
       INDUSTRIAL APPLICABILITY  
       [0014]     The hood positioning apparatus  101  of the present invention has been described herein for use with raising or lowering of hoods  108  that may be too large or unwieldy to be manipulated manually. However, as should be apparent to those of ordinary skill in such art, the hood positioning apparatus  101  of the present invention may be used to raise and lower hoods of any shape and size.  
         [0015]     Activation of the hood positioning apparatus  101  is initiated by manipulating the switching device  246  in the desired manner. To raise the hood  108 , the switching device  246  is placed in the first position denoted  247  thereby energizing both the motor  208  and the directional control valve  220 . Activation of the directional control valve  220  causes the spool  221  of the directional control valve  220  to shift left (as shown in  FIG. 2  for illustrative purposes only) thereby diverting hydraulic fluid to the second hydraulic line  216 . Pressure thereafter builds in the cap end  113  of the hydraulic cylinder  112  until such time as the pressure in the cap end  113  exceeds the combined weight of the hood  108  and any environmental forces acting on the hood  108  such as any wind, at which point the hood  108  shall begin to rise.  
         [0016]     Placing the switching device  246  in the third position  251  allows the operator to stop the movement of the hood  108  anytime during its ascent or descent. Placing the switching device  246  in the third position  251  turns off the motor  208 , thereby ceasing flow of fluid in the hydraulic portion  201  of the circuit  200 , and deactivates the directional control valve  220  which causes the spool  221  to automatically shift to its neutral position shown in  FIG. 2 . The provision of the check valves  217  and  227  prevent fluid flow, and hence pressure loss, out of both the rod end  116  and the cap end  113  of the hydraulic cylinder  112  thereby allowing the hood  108  to be being maintained in its stopped position.  
         [0017]     Finally, to lower the hood  108 , the switching device  246  is placed in the second position  250  which activates motor  208  allowing the pump  205  to supply pressurized fluid to the rod end  116  of the hydraulic cylinder  112 . Because fluid flow out of the cap end  113  is in the direction of arrow  238 , the fluid flow is prevented from flowing freely through the second flow control device  230  but rather is regulated by virtue of the flow metering portion  231 . Hydraulic pressure in the first hydraulic line  213  is communicated to the pilot operated check valve  227  via pilot pressure line  228  which opens the pilot operated check valve  227 , thereby permitting the passage of fluid out of the cap end  113  resulting in the lowering of the hood  108 .  
         [0018]     Also, and as should also be appreciated by those of ordinary skill in such art, the provision of the first flow control device  222  allows for controlled movement of the hood  108  when the center of gravity  109  of the hood  108  passes over, and is thereby located behind, the attachment point  106  of the hood  108  (as shown in  FIG. 1 ). In other words, once the center of gravity  109  passes over the attachment point  106 , the weight of the hood  108  is no longer providing a reactionary load acting on the hydraulic cylinder  112 , but rather providing a “pulling” force on the hydraulic cylinder  112  which would cause the hood  108  to continue to raise at an accelerated and uncontrolled rate. By incorporating the first flow control device  222  into the circuit  200 , the rate of evacuation of fluid pressure from the rod end  116  is limited by the maximum flow rate through the first flow control device  222 .  
         [0019]     Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.