Patent Publication Number: US-6659685-B1

Title: Arrangement for cooling a hydraulic fluid in a hydraulic-powered vibrating compactor

Description:
FIELD OF THE INVENTION 
     The invention relates to an arrangement for achieving efficient cooling of the hydraulic fluid in a hydraulic-powered vibrating compactor. 
     1. Background of the Invention 
     With a hydraulic drive, heat is generated in the hydraulic system due to pressure losses. Known arrangements for cooling the hydraulic fluid of the system include a sufficiently large hydraulic fluid reservoir or a conventional oil cooler. However, small compactors in particular preclude the first of these solutions because an oil cooler is both bulky and expensive. 
     2. Summary of the Invention 
     It is an object of the invention to provide a hydraulic-powered vibrating compactor with efficient cooling of the hydraulic fluid in a simple and cost effective manner. 
     The arrangement of the invention is for cooling hydraulic fluid in a hydraulic-powered vibrating compactor and includes a chassis, a casing mounted on the chassis and a reservoir defining an interior for the hydraulic fluid. The arrangement includes: the reservoir being disposed below the casing and having a lower wall defining a tunnel and an upper wall in spaced relationship to the casing so as to define a passage communicating with the atmosphere external of the casing; the lower wall and the upper wall enclosing at least a portion of the interior; a hydraulic pump connected to the chassis and having a through rotatable shaft defining a free end; a fan wheel mounted on the free end; the hydraulic pump being mounted so as to permit the fan wheel to draw cooling air through the tunnel for cooling the hydraulic fluid in the reservoir; and, means for directing the cooling air from the tunnel and into the passage so as to permit the cooling air to pass over the upper wall to further cool the hydraulic fluid in the reservoir and to discharge to the atmosphere outside of the casing. 
     The arrangement of the invention is especially advantageous because the feasibility of using conventional cooling methods is limited by the size of the machine. 
     Another purpose of the invention is to permit the use of environmentally compatible biofluids which, as is known, cannot withstand high temperatures. This is achieved by configuring the fluid reservoir in the shape of a tunnel and providing the hydraulic pump with a through shaft having a fan wheel mounted on one end. Installed in the duct formed by the tunnel-shaped reservoir, the fan wheel generates a flow of cooling air in the duct and this flow is directed further along the top of the reservoir by a baffle plate. Practical tests using this arrangement have shown that the fluid temperature is reduced by approximately 30° C. and that an operating temperature of approximately 50° C. above ambient is achieved thereby enabling biofluids to also be used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to the drawings wherein: 
     FIG. 1 is a side elevation view of a vibrating compactor with a portion broken away to show the arrangement according to the invention for cooling the hydraulic fluid; and, 
     FIG. 2 is a section view of the vibrating compactor taken along line A—A of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     In FIG. 1, the vibrating base plate  2  of the vibrating compactor is provided with eccentric elements  3  and is attached to the chassis  1  via four vibration dampers  4 . The chassis is equipped with an internal combustion engine  5  driving a hydraulic pump  6 . The pump  6  has a through shaft with a fan wheel  7  mounted on the free end  8  of the shaft. A hydraulic reservoir  9  is mounted on the chassis. The reservoir is so configured that its inner side walls  11  form a duct or tunnel  10  through which the fan wheel  7  draws in air. The air is directed upward with the aid of the baffle plate  12  to the top cover  13  of the compactor casing and then passes over the upper wall  19  of the hydraulic fluid reservoir  9  and is discharged through a grille in the side  14  of the compactor casing facing the handle  16 . The air flow is indicated by the arrows  15  in FIG.  1 . The handle grip is identified by reference numeral  17 . 
     FIG. 2 is a view taken along line A—A of FIG.  1  and shows the shape of the hydraulic reservoir  9 . The inner sidewalls  11  of the reservoir  9  form the duct  10  into which the hydraulic pump  6  and fan wheel  7  extend as shown in FIG.  1 . The outer side walls of the reservoir are identified by reference numeral  18 . 
     It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.