Load reduction

Abstract

A method and apparatus are disclosed for selectively providing a fluid communication path between a plunger element and a contact region of an intermediate element that drives the plunger element. The fluid communication path is suitable for lubricant flow to enable a contact zone to occasionally be lubricated. The apparatus includes an elongate plunger element comprising a first end region, an intermediate element comprising a contact region arranged to selectively abut with and thereby urge a further end region of the plunger element and a spring seat member at the further end region of the plunger element. The spring seat member biases the further end region of the plunger element away from the intermediate element during a portion of a cycle of motion of the plunger element. A fluid communication path is thereby provided between an abutment surface of the further end region and the contact region.

1 . Apparatus for selectively providing a fluid communication path between a plunger element and a contact region of an intermediate element that drives the plunger element, comprising:
 an elongate plunger element comprising a first end region;   an intermediate element comprising a contact region arranged to selectively abut with and thereby urge a further end region of the plunger element; characterized in that the apparatus further comprises   a resilient spring seat member enabled to flex and arranged at said further end region that biases the further end region away from the intermediate element during a portion of a cycle of motion of the plunger element to thereby provides a fluid communication path between an abutment surface of said further end region and said contact region.   
     
     
         2 . The apparatus as claimed in  claim 1 , wherein:
 the intermediate element comprises a tappet received for reciprocating sliding motion in a housing bore of a pump housing of a pump assembly.   
     
     
         3 . The apparatus as claimed in  claim 2 , wherein:
 the tappet comprises at least one through-hole in a cylindrical side wall and/or base wall thereof, said through-hole providing a fluid path portion connected to said fluid communication path.   
     
     
         4 . The apparatus as claimed in  claim 1 , wherein:
 the fluid communication path provides lubricating fluid between said abutment surface and said contact region at an end of a return cycle of the plunger element.   
     
     
         5 . The apparatus as claimed in  claim 1 , wherein:
 the first end region of said plunger element is locatable into a blind end of a pump bore of a pump head of a pump assembly; and   the intermediate element further comprises a drive surface that is driveable by a cam or cam rider element of the pump assembly to thereby urge said contact region against said abutment surface.   
     
     
         6 . The apparatus as claimed in  claim 1 , further comprising:
 a return spring member that urges a surface of the spring seat element away from a pump head of a pump assembly.   
     
     
         7 . The apparatus as claimed in  claim 1  wherein said spring seat member and said plunger element are integrally formed or the spring seat member is secured to said plunger element for movement therewith. 
     
     
         8 . A pump assembly comprising:
 a pump housing having an axially extending opening and at least one housing bore extending generally radially from said opening;   at least one pump head comprising a pump bore having a blind end and secured to said pump housing;   a cam and/or cam rider element in said axially extending opening having an inner surface co-operable with a cam driveshaft and an outer surface co-operable with a drive surface of said intermediate member; and at least one apparatus as set in  claim 1 .   
     
     
         9 . A method of lubricating between a plunger element of a pump assembly and an intermediate element providing drive to the plunger element, the method comprising the steps of:
 driving a first end region of a plunger element in a first reciprocating motion with respect to a blind end of a pump bore of a pump head by selectively urging a contact region of an intermediate element proximate to a further end region of the plunger element in a further reciprocating motion;   via a spring seat member at the further end region of the plunger element, biasing the plunger element away from the intermediate element during a portion of a cycle of motion of the plunger element; and   providing lubricating fluid between an abutment surface of said the further end region and said contact region as the further end region is biased away from the intermediate element.   
     
     
         10 . The method as claimed in  claim 9 , further comprising:
 cooling and removing debris from between the abutment surface and said contact region via the lubricating fluid.   
     
     
         11 . The method as claimed in  claim 9 , further comprising:
 providing a squeeze film layer between the abutment surface and said contact region via the lubricating fluid.   
     
     
         12 . The method as claimed in  claim 9 , further comprising:
 opening and closing a gap between said abutment surface and said contact region each cycle of the plunger element.   
     
     
         13 . The method as claimed in  claim 9 , wherein:
 said portion of a cycle comprises an end of a return cycle of the plunger element in which fluid in the pump bore expands and said first reciprocating motion further comprises a pump cycle portion in which fluid in the pump bore is compressed.   
     
     
         14 . The method as claimed in  claim 9 , further comprising:
 biasing the further end region via a spring seat member integrally formed with said plunger element or via a spring seat member secured to said plunger element for movement therewith.