What is claimed is:
1. A foldable frame comprising:
a first frame unit and a second frame unit pivotally coupled with each other at proximal sides thereof and rotatable with respect to each other between a folded state and an unfolded state, wherein each of the first and second frame units comprises a first mounting member disposed at a first side of the foldable frame and a second mounting member disposed at a second side of the foldable frame;
a middle leg assembly coupled with the first and second frame units at the proximal sides of the first and second frame units, wherein the middle leg assembly comprises:
a third upper member having a first end portion coupled to a proximal end portion of the first mounting member of the first frame unit and a proximal end portion of the first mounting member of the second frame unit by a first coupler disposed at the first side of the foldable frame and a second end portion coupled to a proximal end portion of the second mounting member of the first frame unit and a proximal end portion of the second mounting member of the second frame unit by a second coupler disposed at the second side of the foldable frame;
a first middle leg disposed at the first side of the foldable frame and having an upper end portion connected to the third upper member adjacent the first end portion of the third upper member; and
a second middle leg disposed at the second side of the foldable frame and having an upper end portion connected to the third upper member adjacent the second end portion of the third upper member; and
a single safety enhancement assembly disposed at the first side of the foldable frame to prevent accidental folding of the first and second frame units, wherein the single safety enhancement assembly comprises:
a locking mechanism connected to the first middle leg of the middle leg assembly;
a first enhancement member connected to the first mounting member of the first frame unit and the locking mechanism; and
a second enhancement member connected to the first mounting member of the second frame unit and the locking mechanism,
wherein no additional enhancement member is disposed between the second middle leg of the middle leg assembly and the second mounting member of the first or second frame unit; and
wherein the locking mechanism selectively locks the first and second enhancement members when the first and second frame units are in the unfolded state, thereby preventing accidental folding of the first and second frame units.
2. The foldable frame of claim 1 , wherein:
the locking mechanism comprises a sliding member and a fastening member;
the first enhancement member has one end portion pivotally connected to the first mounting member of the first frame unit and another end portion pivotally connected to the sliding member;
the second enhancement member has one end portion pivotally connected to the first mounting member of the second frame unit and another end portion pivotally connected to the sliding member;
the sliding member is coupled with the first middle leg of the middle leg assembly and movable along the first middle leg of the middle leg assembly; and
the fastening member selectively locks the sliding member with the first middle leg of the middle leg assembly to restrict the sliding member from moving along the first middle leg of the middle leg assembly when the first and second frame units are in the unfolded state, thereby selectively locking the first and second enhancement members when the first and second frame units are in the unfolded state and thus preventing accidental folding of the first and second frame units.
3. The foldable frame of claim 2 , wherein:
the first middle leg of the middle leg assembly comprises a restriction hole; and
the fastening member of the locking mechanism is a pin disposed in the sliding member and insertable into the restriction hole of the first middle leg.
4. The foldable frame of claim 3 , wherein the locking mechanism further comprises an elastic member disposed in the sliding member to push the pin into the restriction hole when the pin is aligned with the restriction hole.
5. The foldable frame of claim 4 , wherein the locking mechanism further comprises a pressing member coupled with the sliding member for applying an external force on the elastic member to pull the pin out of the restriction hole.
6. The foldable frame of claim 2 , wherein the sliding member comprises a slot slidably engaged with the first middle leg of the middle leg assembly.
7. The foldable frame of claim 2 , wherein the sliding member comprises a connecting shaft for pivotally connecting the first and second enhancement members.
8. The foldable frame of claim 1 , wherein:
the locking mechanism comprises a fixation member fixedly coupled with the first middle leg of the middle leg assembly;
the first enhancement member is coupled with the fixation member such that the fixation member is movable along a length direction of the first enhancement member, wherein the first enhancement member comprises a first restriction structure;
the second enhancement member is coupled with the fixation member such that the fixation member is movable along a length direction of the second enhancement member, wherein the second enhancement member comprises a second restriction structure; and
the fixation member of the locking mechanism selectively engages with the first restriction structure of the first enhancement member and the second restriction structure of the second enhancement member when the first and second frame units are in the unfolded state, thereby selectively locking the first and second enhancement members when the first and second frame units are in the unfolded state and thus preventing accidental folding of the first and second frame units.
9. The foldable frame of claim 8 , wherein:
the first enhancement member comprises a first slot along at least a portion of the first enhancement member;
the second enhancement member comprises a second slot along at least a portion of the second enhancement member; and
the fixation member of the locking mechanism is movable along the first slot of the first enhancement member and the second slot of the second enhancement member.
10. The foldable frame of claim 9 , wherein:
the first restriction structure is formed at an end of the first slot of the first enhancement member; and
the second restriction structure is formed at an end of the second slot of the second enhancement member.
11. The foldable frame of claim 1 , wherein:
the first frame unit further comprises a first leg assembly pivotally coupled with the first mounting assembly at a distal side of the first mounting assembly;
the second frame unit further comprises a second leg assembly pivotally coupled with the second mounting assembly at a distal side of the second mounting assembly.
12. The foldable frame of claim 11 , further comprising:
a first supporting assembly coupled with the first leg assembly and first mounting assembly and configured to control rotation of the first leg assembly with respect to the first mounting assembly; and
a second supporting assembly coupled with the second leg assembly and second mounting assembly and configured to control rotation of the second leg assembly with respect to the second mounting assembly.
13. The foldable frame of claim 12 , wherein:
the first supporting assembly is coupled with an intermediate member of the first leg assembly and a lateral mounting bar of the first mounting assembly; and
the second supporting assembly is coupled with an intermediate member of the second leg assembly and a lateral m