Suitcase and suitcase assembly

1. A suitcase, comprising:

a case body having a cuboid shape, comprising:

a front portion;

a rear portion connected to the front portion, wherein the front portion and the rear portion are arranged in a first direction;

a plurality of top cylindrical projections on the rear portion that protrude outwardly in a second direction perpendicular from the first direction;

at least one bottom tubular projection on the rear portion that protrudes outwardly in a third direction opposite from the second direction; and

four sidewalls surrounding the bottom tubular projection, wherein there is a space between the bottom tubular projection and the sidewalls; and

a plurality of wheel assemblies, wherein each of the wheel assemblies comprises a connecting element, and the wheel assemblies are connected to the case body by being closely engaged to the top cylindrical projections or closely engaged in the space by the connecting element.

2. The suitcase as claimed in claim 1 , wherein the case body further comprises a plurality of side cylindrical projections formed on a front side surface of the front portion and a rear side surface of the rear portion, the top cylindrical projections are formed on a rear top surface of the rear portion, and the rear top surface faces a different direction than the front side surface and the rear side surface.

3. The suitcase as claimed in claim 2 , further comprising a fixing member, comprising:

a main body;

at least one fixing tubular projection formed on the main body; and

four fixing sidewalls surrounding the fixing tubular projection, wherein at least one of the side cylindrical projections formed on the front portion and at least one of the side cylindrical projections formed the rear portion are closely engaged with the fixing tubular projection and the fixing sidewalls.

4. The suitcase as claimed in claim 1 , wherein each of the wheel assemblies comprises:

a base;

a wheel connected to one side of the base; and

a wheel cylindrical projection formed on another side of the base, wherein the wheel cylindrical projection is closely engaged in the space.

5. The suitcase as claimed in claim 1 , wherein each of the wheel assemblies comprises:

a base;

a wheel connected to one side of the base; and

four wheel sidewalls formed on another side of the base, wherein at least one of the top cylindrical projections is closely engaged with the wheel sidewalls, and at least one of the top cylindrical projections is closely engaged to the top cylindrical projections.

6. The suitcase as claimed in claim 1 , further comprising a draw bar having a first end and a second end, wherein the first end is connected to the case body, and the second end is opposite the first end and comprises a button having the same shape as one of the top cylindrical projections.

7. The suitcase as claimed in claim 6 , wherein the draw bar further comprises:

a first portion directly connected to the case body; and

a second portion articulately connected to the first portion by an articulate connecting portion between the first portion and the second portion.

8. The suitcase as claimed in claim 1 , further comprising:

a plurality of front cylindrical projections formed on the front portion and extending in the first direction;

at least one rear tubular projection formed on the rear portion and extending in a fourth direction opposite from the first direction; and

four rear sidewalls surrounding the rear tubular projection.

9. The suitcase as claimed in claim 8 , wherein each of the front cylindrical projections has the same dimensions as each of the top cylindrical projections, and the rear tubular projection has the same dimensions as the bottom tubular projection.

10. A suitcase assembly, comprising:

at least two case bodies having a cuboid shape and connected with each other, wherein each of the case bodies comprises:

a front portion;

a rear portion connected to the front portion, wherein the front portion and the rear portion are arranged in a first direction;

a plurality of top cylindrical projections on the rear portion that protrude outwardly in a second direction perpendicular from the first direction;

at least one bottom tubular projection on the rear portion and protrudes outwardly in a third direction opposite from the second direction; and

four sidewalls surrounding the bottom tubular projection; and

a plurality of wheel assemblies, wherein each of the wheel assemblies comprises a connecting element, and the wheel assemblies are connected to one of the case bodies by the connecting element.

11. The suitcase assembly as claimed in claim 10 , wherein at least one of the top cylindrical projections formed on one of the case bodies is closely engaged with the bottom tubular projection and at least one of the sidewalls of another case body.

12. The suitcase assembly as claimed in claim 10 , wherein at least one of the top cylindrical projections formed on one of the case bodies is closely engaged with a plurality of the bottom tubular projections of another case body.

13. A suitcase assembly, comprising:

at least two case bodies having a cuboid shape and connected with each other in a first direction, wherein each of the case bodies comprises:

a front portion having a front surface;

a rear portion connected to the front portion, wherein the front portion and the rear portion are arranged in the first direction, and the rear portion has a rear surface;

a plurality of front cylindrical projections formed on the front portion and protrude outwardly in the first direction;

at least one rear tubular projection formed on the rear portion, wherein the rear tubular projection protrudes outwardly in a second direction opposite from the first direction; and

four sidewalls surrounding the rear tubular projection; and

a plurality of wheel assemblies, wherein each of the wheel assemblies comprises a connecting element, a base, and a wheel, the wheel and the connecting element are connected to the base, and the wheel assemblies are connected to the case bodies by the connecting element, wherein at least one of the front cylindrical projection of one of the case bodies is closely engaged with the rear tubular projection and the sidewalls of another case body, and the wheel of each of the wheel assemblies does not overlap the case bodies in the first direction.

14. The suitcase assembly as claimed in claim 13 , wherein the two case bodies have different dimensions.

15. The suitcase assembly as claimed in claim 13 , further comprising a plurality of draw bars, wherein each of the draw bars has a first portion directly connected to one of the case bodies and a second portion articulately connected to the first portion by an articulate connecting portion between the first portion and the second portion.