Pulse width modulated fluidic valve

Abstract

A pulse width modulated fluidic valve includes a cylinder having an elongate bore, a length and first and second ports which extend from outside the cylinder into the bore. A rotatable spool is carried in the bore and movable in a direction of the length of cylinder. The spool has a variable blocking feature which blocks passage of fluid between the first and second ports as a function of angular position relative to the first and second ports and as a function of linear position along the length of the cylinder.

1 . A pulse width modulated fluidic valve, comprising:
 a housing having an elongate bore, a length and first and second ports which extend from outside the housing into the bore; and   a rotatable spool carried in the bore and movable in a direction of the length of housing, the spool having a variable blocking feature which selectively blocks passage of fluid between the first and second ports as a function of angular position relative to the first and second ports and as a function of linear position along the length of the housing.   
   
   
       2 . The apparatus of  claim 1  including a rotary driver coupled to rotatable spool configure to rotate the rotatable spool. 
   
   
       3 . The apparatus of  claim 2  wherein a speed of rotation is controllable. 
   
   
       4 . The apparatus of  claim 2  wherein the speed of rotation is fixed. 
   
   
       5 . The apparatus of  claim 1  includes a linear displacement driver coupled to the rotatable spool configured to move the spool in a direction along the length of the housing. 
   
   
       6 . The apparatus of  claim 5  wherein the linear displacement driver is responsive to a linear position control input. 
   
   
       7 . The apparatus of  claim 1  wherein the variable blocking feature comprises a seal which provides a seal between the spool and a wall of the bore. 
   
   
       8 . The apparatus of  claim 1  wherein the seal extends linearly along a length of the spool and radially along a circumference of the spool. 
   
   
       9 . The apparatus of  claim 8  wherein the seal is helical. 
   
   
       10 . The apparatus of  claim 1  wherein the variable blocking feature comprises two seals which provide fluidic seals between an outer circumference of the rotatable spool and a wall of the elongate bore of the housing. 
   
   
       11 . The apparatus of  claim 7  wherein the seal is formed relative to a cut out region of the spool. 
   
   
       12 . The apparatus of  claim 7  wherein the seal comprises a raised portion on an outer circumference of the spool. 
   
   
       13 . The apparatus of  claim 1  wherein the rotatable spool is hollow. 
   
   
       14 . The apparatus of  claim 1  wherein the rotatable spool includes a fluidic passageway which extends radially through the spool. 
   
   
       15 . The apparatus of  claim 14  wherein the passageway extends from one side of the variable blocking feature to another side of the variable blocking feature. 
   
   
       16 . A method of controlling flow of a fluid, comprising:
 providing flow of a fluid into a housing;   receiving the flow of the fluid into the housing;   rotating a spool within the housing, the spool including a variable blocking feature;   moving the spool linearly within the housing; and   receiving the fluid at an exit from the housing.   
   
   
       17 . The method of  claim 16  including actuating a rotary driver coupled to rotatable spool configure to rotate the rotatable spool. 
   
   
       18 . The method of  claim 17  wherein a speed of rotation is controllable. 
   
   
       19 . The method of  claim 17  wherein the speed of rotation is fixed. 
   
   
       20 . The method of  claim 16  includes actuating a linear displacement driver coupled to the rotatable spool configured to move the spool in a direction along the length of the housing. 
   
   
       21 . The method of  claim 20  wherein the linear displacement driver is responsive to a linear position control input. 
   
   
       22 . The method of  claim 16  wherein the variable blocking feature comprises a seal which provides a seal between the spool and a wall of the bore. 
   
   
       23 . The method of  claim 22  wherein the seal extends linearly along a length of the spool and radially along a circumference of the spool. 
   
   
       24 . The method of  claim 22  wherein the seal is helical. 
   
   
       25 . The method of  claim 16  wherein the variable blocking feature comprises two seals which provide fluidic seals between an outer circumference of the rotatable spool and a wall of the elongate bore of the housing. 
   
   
       26 . The method of  claim 22  wherein the seal is formed relative to a cut out region of the spool. 
   
   
       27 . The method of  claim 22  wherein the seal comprises a raised portion on an outer circumference of the spool. 
   
   
       28 . The method of  claim 16  wherein the rotatable spool is hollow. 
   
   
       29 . The method of  claim 16  wherein the rotatable spool includes a fluidic passageway which extends radially through the spool. 
   
   
       30 . The method of  claim 16  wherein the spool includes a passageway which extends from one side of the variable blocking feature to another side of the variable blocking feature.