Biomass impact sensor having a conformal encasement enveloping a pressure sensitive film
A biomass impact sensor for sensing impacts of biomass material may include a pressure sensitive film having a first sensing face and a second opposite face, a first layer of a first material composition directly abutting the first sensing face having a first stiffness, and a second layer of a second material composition directly abutting the second opposite face. The first layer and the second layer may be joined along opposite edges of the pressure sensitive film to envelope the sensing material layer on the opposite edges.
1. A biomass impact sensor for sensing impacts of biomass material, the sensor comprising:
a pressure sensitive film having a first sensing face and a second opposite face;
a conformal encasement enveloping the pressure sensitive film so as to directly abut the first sensing face and the second opposite face, the conformal encasement comprising:
a first portion adjacent the first sensing face having a first stiffness;
a second portion adjacent the second opposite face having a second stiffness less than the first stiffness; and
a third portion extending from the first portion to the second portion along side edges of the pressure sensitive film.
2. The biomass impact sensor of claim 1 , wherein the conformal encasement comprises
a first layer directly abutting the first sensing face in forming the first portion; and
a second layer directly abutting the second opposite face in forming the second portion, wherein the first layer and the second layer are in abutment with one another along the side edges of the pressure sensitive film.
3. The sensor of claim 2 , wherein the pressure sensitive film is captured and retained between the first layer and the second layer without adhesives therebetween.
4. The sensor of claim 1 , where the first layer has a thickness of no greater than 1.2 mm.
5. The sensor of claim 4 , wherein the second layer has a thickness of at least 2 mm.
6. The sensor of claim 1 , wherein the second layer has a thickness of at least 2 mm.
7. The sensor of claim 1 , wherein the first stiffness is at least twice the second stiffness.
8. The sensor of claim 1 , wherein the first portion comprises a carbon fiber impregnated with a resin.
9. The sensor of claim 8 , wherein the second portion comprises a glass fiber impregnated with the resin.
10. The sensor of claim 9 , wherein the conformal encasement comprises a single unitary body formed by an integral mass of the resin which impregnates a mat of the carbon fiber in the first portion and which impregnates a mat of the glass fiber in the second portion.
11. The sensor of claim 1 , wherein the pressure sensitive film comprises internal elliptical voids.
12. The sensor of claim 1 , wherein the conformal encasement comprises a mass of resin completely encapsulating all external surfaces of the pressure sensitive film.
13. A biomass impact sensor comprising:
a pressure sensitive film having a first sensing face and a second opposite face;
a first mat of a first fiber having a first stiffness proximate the first sensing face;
a second mat of a second fiber having a second stiffness less than the first stiffness and proximate the second opposite face;
a single continuous unitary mass of resin having a first portion impregnating the first mat, impregnating the second mat and extending between the first mat and the second mat along opposite edges of the pressure sensitive film to envelop the film along the opposite edges.
14. The sensor of claim 13 , wherein the pressure sensitive film is captured and retained between the first mat and the second mat without adhesives therebetween.
15. The sensor of claim 13 , wherein the first mat impregnated with the resin has a first stiffness and wherein the second mat impregnated with resin has a stiffness no greater than one half the first stiffness.
16. The sensor of claim 13 , where the first mat with the impregnated resin has a thickness of no greater than 1.2 mm.
17. The sensor of claim 16 , wherein the second mat with the impregnated resin has a thickness of at least 2 mm.
18. The sensor of claim 13 , wherein the second mat with the impregnated resin has a thickness of at least 2 mm.
19. The sensor of claim 13 , wherein the first mat comprises carbon fibers and wherein the second mat comprises glass fibers.
20. A harvester comprising:
a crop gathering portion to separate crops from a growing medium;
structures defining a pathway extending from the crop gathering portion and through which at least a portion of the crop is directed;
a sensor along the pathway having a sensing face impacted by the portion of the crop, the sensor comprising:
a pressure sensitive film having a first sensing face and a second opposite face;
a conformal encasement enveloping the pressure sensitive film so as to directly abut the first sensing face and the second opposite face, the conformal encasement comprising:
a first portion adjacent the first sensing face having a first stiffness;
a second portion adjacent the second opposite face having a second stiffness less than the first stiffness; and
a third portion extending from the first portion to the second portion along side edges of the pressure sensitive film.