Shock absorber

1. A shock absorber comprising:

a shock absorber body having a cylindrical outer shell, and a piston rod capable of going in/out of the outer shell and adapted to generate a damping force suppressing relative movement of the piston rod in an axial direction with respect to the outer shell;

a cylindrical dust cover connected to the piston rod and adapted to allow entry of the outer shell to an inside;

a cylindrical collar attached to the outer shell and arranged on an outer periphery of the piston rod;

a seal member; and

a cylindrical seal case provided on a piston rod side end of the outer shell, the seal case having

a cylindrical large-diameter portion attached to an inner periphery of the piston rod side end of the outer shell,

an annular flange portion extended from a piston rod side end of the large-diameter portion to an inner periphery side, and

a cylindrical small-diameter portion having a portion extended from the inner periphery of the flange portion to a piston rod side end of the small-diameter portion, wherein

the collar is mounted to the flange portion,

the small-diameter portion accommodates the seal member, and

the collar is welded to the flange portion so as to be fitted to the outer shell through the seal case and surround the small-diameter portion.

2. The shock absorber according to claim 1 , wherein an outer shell side end of the collar is welded and fixed to the seal case over the entire periphery of the outer shell side end of the collar.

3. The shock absorber according to claim 1 , further comprising:

an annular dust filter having an inner periphery attached to the collar and an outer periphery in sliding contact with an inner periphery of the dust cover all the time.

4. The shock absorber according to claim 3 , wherein:

the collar has a flange extended from a piston rod side end of the collar to an outer periphery side; and

the dust filter is fixed by the flange.

5. The shock absorber according to claim 1 , wherein the collar has a flange extended from a piston rod side end of the collar to an outer periphery side.

6. The shock absorber according to claim 1 , wherein an upper end of the collar is set to be higher than an upper end of the seal member in an upright position of the shock absorber where the dust cover is located above the outer shell.

7. A shock absorber comprising:

a shock absorber body having a cylindrical outer shell, and a piston rod capable of going in/out of the outer shell and adapted to generate a damping force suppressing relative movement of the piston rod in an axial direction with respect to the outer shell;

a cylindrical dust cover connected to the piston rod and adapted to allow entry of the outer shell to an inside;

a cylindrical collar attached to the outer shell and arranged on an outer periphery of the piston rod to be on an outside of the outer shell; and

a seal member for sealing the outer periphery of the piston rod, wherein

the outer shell has a bent portion having a piston rod side end bent to an inner periphery side;

the collar has an annular fixing flange extended from an outer shell side end to an outer periphery side;

the collar is attached to the outer shell by gripping the fixing flange by the bent portion; and

the bent portion is configured to fix the seal member to the outer shell.

8. The shock absorber according to claim 7 , further comprising an annular dust filter having an inner periphery attached to the collar and an outer periphery in sliding contact with an inner periphery of the dust cover all the time.

9. The shock absorber according to claim 7 , wherein the annular fixing flange is in direct contact with the bent portion.