Precision flow gear pump

Abstract

A positive displacement gear pump including a pump housing having an inlet port, an outlet portion, and first and second pumping chambers. A first gear having helical teeth is engaged with an inner surface of the first pumping chamber. A second gear with helical teeth is engaged with an inner surface of the second pumping chamber. At least two teeth on the first and second gears are simultaneously meshed in a meshed region. A first bearing element is located at one end surface of the first and second gears. The first bearing insert includes at least a first outlet channel fluidly coupling an outlet portion of the meshed region to the outlet port.

1 . A positive displacement gear pump comprising:
 a pump housing having an inlet port, an outlet port, and first and second pumping chambers;   a first gear having helical teeth engaged with an inner surface of the first pumping chamber and a second gear with helical teeth engaged with an inner surface of the second pumping chamber, at least two teeth on the first and second gears simultaneously meshed in a meshed region; and   a first bearing insert located at a first end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the first bearing insert including a first outlet channel fluidly coupling an outlet portion of the meshed region with the outlet port.   
   
   
       2 . The positive displacement gear pump of  claim 1  wherein the first bearing insert comprises a first inlet channel fluidly coupling an inlet portion of the meshed region with the inlet port, and a first land region separating the first outlet channel from the first inlet channel. 
   
   
       3 . The positive displacement gear pump of  claim 2  wherein the first land region prevents fluid communication between the inlet port and the outlet port. 
   
   
       4 . The positive displacement gear pump of  claim 2  wherein the location of the first land region is a function of an angle of the helical teeth. 
   
   
       5 . The positive displacement gear pump of  claim 2  wherein the first land region has a length separating the inlet channels from the outlet channels on the first bearing insert that is greater than or equal to a width of the teeth at a pitch circle. 
   
   
       6 . The positive displacement gear pump of  claim 2  wherein a width of the inlet channels and the outlet channels on the first bearing insert is greater than or equal to twice the addendum of the teeth. 
   
   
       7 . The positive displacement gear pump of  claim 1  comprising a second bearing insert located at a second end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the second bearing insert including a second outlet channel fluidly coupling the outlet portion of the meshed region with the outlet port, a second inlet channel fluidly coupling the inlet portion of the meshed region with the inlet port, and a second land region separating the second outlet channel from the second inlet channel. 
   
   
       8 . The positive displacement gear pump of  claim 1  comprising a second bearing insert located at a second end of the first and second pumping chambers and engaged with end surfaces of the first and second gears. 
   
   
       9 . The positive displacement gear pump of  claim 8  comprising:
 third and fourth gears having an axial length different from an axial length of the first and second gears; and   third and fourth bearing insert having a thickness different than a thickness of the first and second bearing insert, so an axial length of the third and fourth gear and the third and fourth bearing insert is the same as an axial length of the first and second gears and the first and second bearing insert.   
   
   
       10 . The positive displacement gear pump of  claim 9  wherein a third outlet channel on the third bearing insert comprises a length different than a length of the first outlet channel on the first bearing insert. 
   
   
       11 . The positive displacement gear pump of  claim 8  comprising:
 third and fourth gears with a tooth helix angle different from a tooth helix angle on the first and second gears; and   third and fourth bearing inserts having a thickness different than the first and second bearing inserts, so an axial length of the third and fourth gear and the third and fourth bearing inserts is the same as an axial length of the first and second gears and the first and second bearing inserts.   
   
   
       12 . The positive displacement gear pump of  claim 1  wherein the first and second gears and the first bearing inserts are removable from the pump housing. 
   
   
       13 . The positive displacement gear pump of  claim 1  wherein the meshed region comprises at least two line contacts between the first and second gears that form a fluid-tight barrier between the inlet port and the outlet port. 
   
   
       14 . A positive displacement gear pump comprising:
 a pump housing having an inlet port, an outlet port, and first and second pumping chambers;   a first gear having helical teeth engaged with an inner surface of the first pumping chamber and a second gear with helical teeth engaged with an inner surface of the second pumping chamber, the first and second gears comprising teeth at a helical angle so that at least two teeth are simultaneously meshed in a meshed region; and   a first bearing insert located at a first end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the first bearing insert including a first outlet channel fluidly coupling an outlet portion of the meshed region with the outlet port, a first inlet channel fluidly coupling an inlet portion of the meshed region with the inlet port, and a first land region separating the first outlet channel from the first inlet channel.   
   
   
       15 . A positive displacement gear pump comprising:
 a pump housing having an inlet port, an outlet port, and first and second pumping chambers;   a first gear having helical teeth engaged with an inner surface of the first pumping chamber and a second gear with helical teeth engaged with an inner surface of the second pumping chamber, at least two teeth on the first and second gears simultaneously meshed in a meshed region;   a first bearing insert located at a first end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the first bearing insert including a first outlet channel fluidly coupling an outlet portion of the meshed region with the outlet port, a first inlet channel fluidly coupling an inlet portion of the meshed region with the inlet port, and a first land region separating the first outlet channel from the first inlet channel; and   a second bearing insert located at a second end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the second bearing insert including a second outlet channel fluidly coupling the outlet portion of the meshed region with the outlet port, a second inlet channel fluidly coupling the inlet portion of the meshed region with the inlet port, and a second land region separating the second outlet channel from the second inlet channel.   
   
   
       16 . The positive displacement gear pump of  claim 15  comprising:
 third and fourth gear having an axial length different from an axial length of the first and second gears; and   third and fourth bearing inserts having a thickness different than a thickness of the first and second bearing inserts, so an axial length of the third and fourth gear and the third and fourth bearing inserts is the same as an axial length of the first and second gears and the first and second bearing inserts.   
   
   
       17 . A positive displacement gear pump comprising:
 a pump housing having an inlet port, an outlet port, and first and second pumping chambers;   a first gear having helical teeth engaged with an inner surface of the first pumping chamber and a second gear with helical teeth engaged with an inner surface of the second pumping chamber, at least two teeth on the first and second gears simultaneously meshed in a meshed region;   a first bearing insert located at a first end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the first bearing insert including an outlet channel fluidly coupling an outlet portion of the meshed region with the outlet port; and   a second bearing insert located at a second end of the first and second pumping chambers and engaged with end surfaces of the first and second gears.   
   
   
       18 . A positive displacement gear pump comprising:
 a pump housing having an inlet port, an outlet port, and first and second pumping chambers;   a first gear having helical teeth engaged with an inner surface of the first pumping chamber and a second gear with helical teeth engaged with an inner surface of the second pumping chamber, at least two teeth on the first and second gears simultaneously meshed in a meshed region;   a first bearing insert located at a first end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the first bearing insert including an outlet channel fluidly coupling an outlet portion of the meshed region with the outlet port; and   a second bearing insert located at a second end of the first and second pumping chambers and engaged with end surfaces of the first and second gears, the second bearing insert including a second inlet channel fluidly coupling an inlet portion of the meshed region with the inlet port.