Elastic Cord Unit for Pull Exerciser

Abstract

An elastic cord unit includes a hollow outer elastic cord having a first longitudinal hole and two ends. Two first stops are respectively and securely received in the ends of the outer elastic cord. A hollow inner elastic cord is received in the outer elastic cord and includes a second longitudinal hole. Two ends of the inner elastic cord are respectively received in the first stops. Two second stops are respectively received in the ends of the inner elastic cord. Each end of the inner elastic cord is securely clamped between one of the first stops and one of the second stops. When the outer elastic cord breaks while a user is stretching the elastic cord unit, the inner elastic cord does not break to avoid injury to the user.

1 . An elastic cord unit comprising:
 a hollow outer elastic cord including a first longitudinal hole and two ends;   two first stops respectively and securely received in the two ends of the outer elastic cord;   a hollow inner elastic cord received in the outer elastic cord and including a second longitudinal hole, with the inner elastic cord further including two ends respectively received in the two first stops; and   two second stops respectively received in the two ends of the inner elastic cord, with each of the two ends of the inner elastic cord being securely clamped between one of the two first stops and one of the two second stops.   
   
   
       2 . The elastic cord unit as claimed in  claim 1 , with the outer elastic cord having an elastic coefficient larger than that of the inner elastic cord. 
   
   
       3 . The elastic cord unit as claimed in  claim 1 , with each of the two first stops including a through-hole receiving one of the two second stops and having an enlarged section, with each of the two first stops further including a first larger section having an outer diameter larger than that of each of the two ends of the outer elastic cord, with the enlarged section of the through-hole being formed in the first larger section, with each of the two first stops further including a first smaller section having an outer diameter smaller than that of the first larger section, with each of the two second stops including a second larger section having an outer diameter larger than a diameter of the through-hole and larger than an outer diameter of each of the two ends of the inner elastic cord but smaller than the outer diameter of the first larger section, with each of the two second stops further including a second smaller section having an outer diameter smaller than that of the second larger section, with the second larger section of each of the two second stops being received in the first larger section of one of the two first stops, and with the second smaller section of each of the two second stops being received in the first smaller section of one of the two first stops. 
   
   
       4 . The elastic cord unit as claimed in  claim 3 , with the outer elastic cord further including a first intermediate portion between the two ends thereof, with the inner elastic cord further including a second intermediate portion between the two ends thereof, and with the second intermediate portion being received in and spaced from the first intermediate portion. 
   
   
       5 . The elastic cord unit as claimed in  claim 3 , with each of the two ends of the inner elastic cord including an inner section, a turnback section, and a turn integrally connecting the turnback section with the inner section as a single continuous monolithic piece, with the turnback section facially abutting and extending outside and surrounding the inner section, with the turnback section having a length larger than that of each of the two second stops, and with the turnback section and the inner section being securely clamped between the one of the two first stops and one of the two second stops. 
   
   
       6 . The elastic cord unit as claimed in  claim 3 , with each of the two ends of the outer elastic cord including an inner section, a turnback section, and a turn integrally connecting the turnback section with the inner section as a single continuous monolithic piece, with the turnback section facially abutting and extending outside and surrounding the inner section, and with the turnback section having a length larger than that of each of the two first stops. 
   
   
       7 . The elastic cord unit as claimed in  claim 4 , with each of the two ends of the outer elastic cord including an inner section, a turnback section, and a turn integrally connecting the turnback section with the inner section as a single continuous monolithic piece, with the turnback section facially abutting and extending outside and surrounding the inner section, and with the turnback section having a length larger than that of each of the two first stops. 
   
   
       8 . An elastic cord unit comprising:
 a hollow outer elastic cord including a longitudinal hole and two ends;   two stops respectively and securely received in the two ends of the outer elastic cord, with each of the two stops including a through-hole having an enlarged section, with each of the two stops further including a larger section having an outer diameter larger than that of each of the two ends of the outer elastic cord, with the enlarged section of the through-hole being formed in the larger section; and   an inner elastic cord received in the outer elastic cord and including a second longitudinal hole and two ends, with each of the two ends of the inner elastic cord extending through the through-hole of one of the two stops and including a knotted portion having a maximum width larger than a diameter of the through-hole, with the knotted portion of each of the two ends of the inner elastic cord being received in the enlarged section of the through-hole of one of the two stops.   
   
   
       9 . The elastic cord unit as claimed in  claim 8 , with the outer elastic cord having an elastic coefficient larger than that of the inner elastic cord. 
   
   
       10 . The elastic cord unit as claimed in  claim 8 , the outer elastic cord further including a first intermediate portion between the two ends thereof, with the inner elastic cord further including a second intermediate portion between the two ends thereof, and with the second intermediate portion being received in and spaced from the first intermediate portion. 
   
   
       11 . The elastic cord unit as claimed in  claim 9 , with each of the two ends of the outer elastic cord including an inner section, a turnback section, and a turn integrally connecting the turnback section with the inner section as a single continuous monolithic piece, with the turnback section facially abutting and extending outside and surrounding the inner section, and with the turnback section having a length larger than that of each of the two stops.