Driving device for a hub assembly

1. A driving device adapted for use in a hub assembly, said driving device comprising:

a stationary ring adapted to be mounted fixedly in the hub assembly, and having

an inner ring surface that surrounds an axis and that defines an inner ring hole, and

a plurality of angularly spaced-apart ratchet grooves that are formed in said inner ring surface and that are in spatial communication with said inner ring hole, each of said ratchet grooves having an outline that is symmetrical with respect to a plane extending from the axis through a central axis of said ratchet groove;

a connecting seat having

a surrounding wall that surrounds the axis and that has an outer surrounding surface,

a sprocket that surrounds and is connected to said surrounding wall, and

at least one connecting portion that is formed on said outer surrounding surface of said surrounding wall, said connecting portion being configured as a recess, said at least one connecting portion and said sprocket being arranged along the axis; and

a pawl unit including

a coupling seat that is ring-shaped, that is removably sleeved on said connecting seat, and that has

an internal surrounding surface surrounding the axis,

an external surrounding surface opposite to said internal surrounding surface,

at least one coupling portion formed on said internal surrounding surface and engaging removably said at least one connecting portion of said connecting seat, said coupling portion being configured as a protrusion, and

a plurality of angularly spaced-apart retaining grooves formed in said external surrounding surface, each of said retaining grooves having a central section that has an opening, and first and second retaining sections that are connected respectively to circumferentially opposite ends of said central section,

a plurality of pawls, each of which has an engaging end that engages rotatably said first retaining section of a respective one of said retaining grooves of said coupling seat, and a claw end that is opposite to said engaging end and that extends through said opening of the respective one of said retaining grooves, and

a plurality of resilient members, each of which is disposed in said second retaining section of a respective one of said retaining grooves for biasing said claw end of a respective one of said pawls to engage a corresponding one of said ratchet grooves of said stationary ring;

wherein said connecting seat has a plurality of said connecting portions that are angularly spaced-apart from each other;

wherein said coupling seat of said pawl unit has a plurality of said coupling portions that engage respectively said connecting portions of said connecting seat; and

wherein each of said coupling portions of said coupling seat of said pawl unit is radially aligned with a respective one of said retaining grooves.

2. The driving device as claimed in claim 1 , wherein:

said connecting seat further has

an abutment ring that surrounds and is connected to said surrounding wall, and that is disposed between said at least one connecting portion and said sprocket, and

a ring groove that is formed in said outer surrounding surface of said surrounding wall and that is disposed at a side of said at least one connecting portion opposite to said abutment ring along the axis; and

said driving device further comprises a C-ring that is removably retained in said ring groove, said pawl unit being positioned between said C-ring and said abutment ring.