Apparatuses, systems, and methods for adjusting the effective stroke-length of a positive displacement pump

Abstract

This disclosure covers systems, apparatuses, and methods for adjusting the effective stroke-length of positive displacement pumps by means of generating lost motion between the crosshead of the pump and the piston/plunger of the pump head. The teachings herein are of particular importance for the purposes of tuning the flowrate of metering pumps and permits for the independent tuning of individual heads of multiplex pumps. Various embodiments of such adjustment mechanisms may provide for relatively gross or fine tuning of the amount of motion loss occurs. Similarly, various embodiments may provide for either discrete or relatively continuous adjustment of the amount of lost motion may be so generated.

We claim: 
     
         1 . An adjustment mechanism for adjusting the effective stroke length of a positive displacement pump comprising:
 a sleeve configured to engage with a crosshead of a positive displacement pump and when so engaged to extend beyond a distal end of the crosshead, the sleeve comprising a channel through which a portion of a plunger may travel, the plunger configured to travel freely relative to the sleeve and the crosshead along an axis of motion, wherein the sleeve is configured to mechanically engage with the plunger such that a distance of travel of the plunger along the axis of motion during a cycle is less than a distance of travel of the crosshead along the axis of motion during the cycle.   
     
     
         2 . The adjustment mechanism of  claim 1 , wherein the plunger comprises a flange located at a proximal end of the plunger, and wherein the flange is positioned inside of an interior volume of the crosshead, between a proximal end of the sleeve and the crosshead, and wherein a dimension of the flange is smaller than a corresponding interior dimension of the crosshead, and larger than a corresponding dimension of the proximal end of the sleeve, such that the flange is restricted from exiting the interior volume by traveling through the channel. 
     
     
         3 . The adjustment mechanism of  claim 2 , wherein a proximal surface of the sleeve sized to restrict travel of a proximal end of the plunger through the channel. 
     
     
         4 . The adjustment mechanism of  claim 2 , further comprising a pin configured to be inserted into a hole in the sleeve and extend into the channel, and wherein the pin is configured to mechanically engage with a proximal end of the plunger and to limit travel of the plunger responsive to corresponding travel of the crosshead. 
     
     
         5 . The adjustment mechanism of  claim 2 , wherein the sleeve is releasably engageable with the crosshead at a plurality of positions along the axis of motion. 
     
     
         6 . The adjustment mechanism of  claim 2 , wherein an exterior surface of the sleeve comprises threading and an interior surface of the crosshead comprises treading complimentary to the threading on the sleeve such that the sleeve may be screwably coupled with the crosshead. 
     
     
         7 . An adjustment mechanism for a positive displacement pump comprising:
 a sleeve configured to be positioned around a portion of a plunger of the positive displacement pump and between said portion of the plunger and a crosshead of the positive displacement pump, wherein the sleeve comprises a threaded outer surface configured to screwably engage with complimentary threading on the crosshead, and defining a channel configured to permit the travel of the portion of the plunger therethrough while restricting travel of a proximal end of the plunger therethrough.   
     
     
         8 . The adjustment mechanism of  claim 7 , further comprising a collar located at a distal end of the sleeve, wherein a dimension of the collar is greater than a corresponding dimension of a distal end of the crosshead such that the collar is prevented from being inserted into the crosshead. 
     
     
         9 . The adjustment mechanism of  claim 8 , wherein the collar comprises features along an outer edge of the collar, said features being configured to facilitate rotation of the adjustment mechanism relative to the crosshead. 
     
     
         10 . The adjustment mechanism of  claim 7 , further comprising a locking nut comprising threading complimentary to that of the outer surface of the sleeve, wherein the locking nut is configured to be screwably engaged with the sleeve and wherein the locking nut comprises a dimension greater than a corresponding dimension of a distal end of the crosshead such that when the locking nut is screwed onto the sleeve and the sleeve is screwed into the crosshead the locking nut may abut a distal end of the crosshead and thereby prevent the sleeve from being further screwed inserted into the crosshead. 
     
     
         11 . A pump comprising:
 a plunger running through and coaxial with an adjustment mechanism comprising a sleeve having a threaded exterior surface, the plunger configured to travel freely along an axis of translation relative to the adjustment mechanism, the treaded exterior surface engageable with a threaded interior surface of a crosshead;   the adjustment mechanism and crosshead configured such that a distal end of the adjustment mechanism extends beyond a distal end of the crosshead, so that rotation of the adjustment mechanism relative to the crosshead causes the adjustment mechanism to travel along the axis of translation relative to the crosshead, and so that, when engaged with the crosshead, the adjustment mechanism travels along the axis of translation with the crosshead during a cycle;   a proximal end of the adjustment mechanism configured to cause the plunger to travel with the adjustment mechanism during a portion of a backwards stroke of the crosshead, wherein the portion of the stroke of the crosshead through which the plunger is made to travel due to its engagement with the adjustment mechanism is less than a length of a complete stroke of the crosshead.   
     
     
         12 . The pump of  claim 11 , further comprising:
 a plunger sleeve running disposed around a length a proximal end of the plunger and running through and coaxial with an adjustment mechanism between the adjustment mechanism and the plunger, the plunger sleeve configured to travel freely along the axis of translation relative to the adjustment mechanism.   
     
     
         13 . The pump of  claim 11 , wherein the adjustment mechanism is configured such that the adjustment mechanism does not motivate motion of the plunger until after the crosshead has traveled some distance during a backwards stroke of the cycle. 
     
     
         14 . The pump of  claim 11 , further comprising a locking nut configured to be screwably engageable with the threaded exterior surface, positioned between the crosshead and the adjustment mechanism, and further configured such that when screwed down such that the locking nut engages with a distal end of the crosshead, the locking nut secures the adjustment mechanism in place relative to the crosshead. 
     
     
         15 . A pump comprising:
 a crosshead defining an interior volume, an interior surface of the crosshead comprising threading;   an adjustment sleeve comprising a proximal end, a distal end, an inner surface, and an outer surface, wherein a portion of the outer surface of the adjustment sleeve starting substantially at the distal end of the adjustment sleeve comprising threading, the threading of the adjustment sleeve configured to screwably engage with the threading of the crosshead, the proximal end of the adjustment sleeve being sized to be retained within the interior volume of the crosshead, and the adjustment sleeve being configured to translate along an axis of translation while the proximal end of the adjustment sleeve is retained within the interior volume of the crosshead; and   a plunger running through the adjustment sleeve, and having a distal end extending therefrom, opposite the crosshead, wherein the plunger is floating relative to the adjustment sleeve and crosshead and configured to translate along the axis of translation responsive to translation of the crosshead along the axis of translation.   
     
     
         16 . The pump of  claim 15 , further comprising a nut, wherein the nut may engage the crosshead and the adjustment sleeve, and which may provide for releasable mechanical engagement therebetween. 
     
     
         17 . The pump of  claim 15 , further comprising:
 a plunger sleeve positioned around a proximal end of the plunger, between the plunger and the adjustment sleeve, wherein the plunger sleeve is floating relative to the adjustment sleeve and the crosshead, and wherein a proximal end of the plunger sleeve is configured to be retained within the interior volume, between the crosshead and the adjustment sleeve, and is sized so as to be prevented from escaping therefrom by the adjustment mechanism.   
     
     
         18 . The pump of  claim 17 , further comprising a flange extending from an exterior surface of the plunger sleeve, the flange being sized and position be restricted from escaping the interior volume by engaging a proximal surface of the adjustment sleeve. 
     
     
         19 . A pump comprising:
 a crosshead defining an interior volume, an interior surface of the crosshead comprising threading;   an adjustment sleeve comprising a proximal end, a distal end, an inner surface, and an outer surface, wherein a portion of the outer surface of the adjustment sleeve starting substantially at the distal end of the adjustment sleeve comprising threading, the threading of the adjustment sleeve is configured to screwably engage with the threading of the crosshead, the distal end of the adjustment sleeve sized to be retained within the interior volume of the crosshead, and wherein the adjustment sleeve is configured to be translated in an axis of translation; and   a plunger configured to be floating respective to the adjustment mechanism and the crosshead while a distal end of the adjustment sleeve is retained within the interior volume of the crosshead, and translatable coaxially along the axis of motion responsive to the translation of the crosshead.   
     
     
         20 . The pump of  claim 19 , further comprising a nut, wherein the nut may engage the crosshead and the adjustment sleeve, and which may provide for releasable mechanical engagement therebetween. 
     
     
         21 . A method of reducing the effective stroke-length of a plunger in a positive displacement pump by means of lost motion, comprising:
 affixing an adjustment mechanism to a crosshead between the crosshead and a plunger whereby the plunger may travel an axis of motion independently of the adjustment mechanism or the crosshead, the adjustment mechanism permitting the plunger to remain stationary relative to travel of the crosshead and the adjustment mechanism along the axis of motion for a portion of a total displacement of the crosshead during a cycle of the pump, and wherein the adjustment mechanism mechanically engages the plunger after travelling the portion of the total displacement of the crosshead and motivates the plunger to travel in the axis of motion responsive to motion of the crosshead for a remainder of the total displacement of the crosshead during the cycle.