Bellows for consant-velocity joints

Abstract

A convoluted boot for sealing an annular gap between two parts which are connected to one another in a rotationally fast way, which can be articulated relative to one another and which are axially displaceable relative to one another, especially of a constant velocity plunging joint, consisting of a low-strain polymer hard material, having a first larger collar 11 to be secured to a first component, a second smaller collar 12 to be secured to a second component and a plurality of annular fold units which extend between the first collar and the second collar and which, in the form of outer folds consisting of two annular flanks 31, 32 , form a fold peak 21 between two fold valleys 22, in a first group A of at least three annular folds with a connection to the first collar 11 , the diameters of the fold peaks 21 and fold valleys 22 decrease in the direction from the first collar to the second collar, in a second group B of annular folds with a connection to the second collar 12 of at least one fold, the diameters of the fold valleys and optionally of the fold peaks 21 are constant, the ratio of the diameter D 1 of the fold peak 21 of the largest annular fold A 1 of the first group A to the diameter D 2 of the second collar 12 amounts to ≧2.5.

1 . A convoluted boot for sealing an annular gap between two parts which are connected to one another in a rotationally fast way, which can be articulated relative to one another and which are axially displaceable relative to one another, the boot comprising: 
 a low-strain hard polymer material, having a first larger collar ( 11 ) to be secured to a first component, a second smaller collar ( 12 ) to be secured to a second component and a plurality of annular fold units which extend between the first collar and the second collar and which, in the form of outer folds comprising two annular flanks ( 31 ,  32 ), form a fold peak ( 21 ) between two fold valleys ( 22 );    wherein, in a first group (A) of at least three annular folds with a connection to the first collar ( 11 ), the diameters of the fold peaks ( 21 ) and fold valleys ( 22 ) decrease from the first collar to the second collar, and    wherein in a second group (B) of at least one annular fold with a connection to the second collar ( 12 ), the diameters of the fold valleys are constant; and    wherein the ratio of the diameter (D 1 ) of the fold peak ( 21 ) of the largest annular fold (A 1 ) of the first group (A) to the diameter (D 2 ) of the second collar ( 12 ) is greater than or equal to 2.5 and the two annular flanks ( 31 ,  32 ) of each of the annular folds of the first group (A) form opposed angles with a radial plane (R), wherein a smaller angle (β) is formed by the annular flank ( 32 ) pointing towards the second collar ( 12 ) and wherein a larger angle (α) is formed by the annular flank pointing towards the first collar ( 11 ), the larger angle (α) being at least 25° greater than the smaller angle (β).    
   
   
       2 . A convoluted boot according to  claim 1 , wherein the first group (A) comprises up to five annular folds.  
   
   
       3 . A convoluted boot according to  claim 1  wherein the second group (B) comprises up to eight annular folds.  
   
   
       4 . A convoluted boot according to  claim 1  wherein the annular flanks ( 31 ,  32 ) of each of the annular folds of the second group (B) form opposed angles with a radial plane, wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms first angle (β) and wherein the annular flank ( 31 ) pointing towards first collar ( 11 ) forms a second angle (α) being in a range from 5° smaller to 5° greater than the first angle (β).  
   
   
       5 . A convoluted boot according to  claim 1  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there are provided transition folds (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       6 . A convoluted boot according to  claim 5 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       7 . A convoluted boot according to  claim 1  wherein the convoluted boot comprises a thermoplastic elastomer (TPE).  
   
   
       8 . A convoluted boot according to  claim 7 , wherein the TPE comprises a polyurethane (TPU).  
   
   
       9 . A convoluted boot according to  claim 7 , wherein the TPE comprises a polyester (TPEE).  
   
   
       10 . A convoluted boot according to  claim 9 , wherein the TPEE is a polyether ester or a polyester ester.  
   
   
       11 . A convoluted boot according to  claim 7 , wherein the TPE comprises a polyamide (TPA).  
   
   
       12 . A convoluted boot according to  claim 7 , wherein the TPE comprises a polyolefin (TPO).  
   
   
       13 . A convoluted boot according to  claim 12 , wherein the TPO is a polypropylene or a polyethylene.  
   
   
       14 . A convoluted boot according to  claim 1  wherein the diameters of the fold peaks ( 21 ) of the second group (B) of annular folds are constant.  
   
   
       15 . A convoluted boot according to  claim 2  wherein the second group (B) comprises up to eight annular folds.  
   
   
       16 . A convoluted boot according to  claim 2  wherein the annular flanks ( 31 ,  32 ) of each of the annular folds of the second group (B) form opposed angles with a radial plane, wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms first angle (β) and wherein the annular flank ( 31 ) pointing towards first collar ( 11 ) forms a second angle (α) which differs from the first angle (β) not more than 5°.  
   
   
       17 . A convoluted boot according to  claim 3  wherein the annular flanks ( 31 ,  32 ) of each of the annular folds of the second group (B) form opposed angles with a radial plane, wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms first angle (β) and wherein the annular flank ( 31 ) pointing towards first collar ( 11 ) forms a second angle (α) which differs from the first angle (β) not more than 5°.  
   
   
       18 . A convoluted boot according to  claim 2  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there is provided at least one transition fold (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       19 . A convoluted boot according to  claim 3  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there is provided at least one transition fold (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       20 . A convoluted boot according to  claim 4  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there is provided at least one transition fold (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       21 . A convoluted boot according to  claim 16  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there is provided at least one transition fold (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       22 . A convoluted boot according to  claim 7  wherein, between the annular folds of the first group (A) and the annular folds of the second group (B), there is provided at least one transition fold (C) whose diameters deviate from one another at the fold valleys ( 22 ), wherein the diameter of the fold valley at the annular flank ( 31 ) pointing towards the first collar ( 11 ) is greater than the diameter of the fold valley at the annular flank ( 32 ) pointing towards the second collar ( 12 ).  
   
   
       23 . A convoluted boot according to  claim 18 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       24 . A convoluted boot according to  claim 19 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       25 . A convoluted boot according to  claim 20 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       26 . A convoluted boot according to  claim 21 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       27 . A convoluted boot according to  claim 22 , wherein the annular flanks ( 31 ,  32 ) of the transition fold (C) form opposed angles with a radial plane (R), wherein the annular flank ( 32 ) pointing towards the second collar ( 12 ) forms a first angle (β) and that the annular flank ( 31 ) pointing towards the first collar ( 11 ) forms a second angle (α) which is defined by (β+25°)≧α≧(β+5°).  
   
   
       28 . A convoluted boot according to  claim 27  wherein the convoluted boot comprises a thermoplastic elastomer (TPE).