Reinforced flexible hose

Abstract

A reinforced flexible hose includes at least one inner tubular layer ( 2 ) of plastic or rubber, a knitted reinforcement ( 3 ), which has substantially, parallel rows ( 4 ) and lines ( 5 ) of substantially parallel stitches, with respective stitch counts per unit length of the hose (Nm, Nr); and an outer layer ( 6 ) which is superimposed on the reinforcement layer ( 3 ) to protect it. The knitted reinforcement layer ( 3 ) is provided in the form of a single tubular layer and is wrapped around the outer surface of the inner tubular layer ( 2 ); the rows ( 4 ) and lines ( 5 ) of stitches are substantially helical, with respective longitudinal pitches (P m , P r ) and inclinations which are mutually opposite with respect to the longitudinal axis (Y). The longitudinal pitch 2 (P r ) of the lines ( 5 ) of stitches is substantially proportional to the square of the outside diameter (φ o ) of the inner layer ( 2 ), whilst the number of lines (N r ) of stitches per unit length of the hose is directly proportional to the outside diameter (φ o ) of the inner layer ( 2 ).

1. Reinforced flexible hose, comprising:
 at least one inner tubular layer ( 2 ) of plastic or rubber which has an outside (φ e ) diameter and a longitudinal axis (Y); 
 a chain knitted-type reinforcement layer ( 3 ), which has rows ( 4 ) of substantially parallel stitches and lines ( 5 ) of substantially parallel stitches, with respective stitch counts per unit length (N m , N r ) in a longitudinal direction; 
 said knitted reinforcement layer ( 3 ) being provided in the form of a single tubular layer and being formed on the outer surface of said inner tubular layer ( 2 ) coaxially thereto; 
 said rows ( 4 ) of stitches and said lines ( 5 ) of stitches being substantially helical with respective longitudinal pitches (P m , P r ) and inclinations (α, β) which are mutually opposite with respect to the longitudinal axis (Y), so as to eliminate the torque applied by-the pressure of the fluid inside it; and 
 an outer layer ( 6 ) which is superimposed on said reinforcement layer ( 3 ) to protect it; 
 characterized in that the longitudinal pitch (P r ) of said lines ( 5 ) of stitches is substantially proportional to the square of the outside diameter (φ o ) of said inner layer ( 2 ). 
 
     
     
       2. Flexible hose according to  claim 1 , characterized in that the number of lines of stitches per unit length (N r ) is substantially directly proportional to the outside diameter (φ o ) of said inner layer ( 2 ). 
     
     
       3. Flexible hose according to  claim 1 , characterized in that the longitudinal pitch (P m ) of the rows of stitches is substantially constant and independent of the outside diameter (φ o ) of said inner layer ( 2 ). 
     
     
       4. Flexible hose according to  claim 1 , characterized in that said rows ( 4 ) and said lines ( 5 ) of substantially helical stitches have different inclination angles (α, β) whose sum is substantially constant and equal to, or slightly lower than, 90° as the value of the outside diameter (φ o ) of said inner layer ( 2 ) varies. 
     
     
       5. Flexible hose according to  claim 4 , characterized in that the angle of inclination (β) of the lines ( 5 ) of stitches is substantially proportional to the square root of the outside diameter (φ o ) of said inner layer ( 2 ). 
     
     
       6. Flexible hose according to  claim 1 , characterized in that in said inner layer ( 2 ) the outside diameter (φ o ) is between 12 and 27 mm and the inside diameter (φ i ) is between 10 and 32 mm. 
     
     
       7. Flexible hose according to  claim 1 , characterized in that the number of rows per unit length (N m ) is substantially constant as the outside diameter (φ o ) of said inner layer ( 2 ) varies, and is between 30 and 40 rows per 100 mm, with an average number of 35 rows per 100 mm. 
     
     
       8. Flexible hose according to  claim 1 , characterized in that the number of lines per unit length (N r ) is substantially proportional to the outside diameter (φ o ) of said inner layer ( 2 ) and is between 10 and 16 lines per 100 mm.