Patent ID: 8720404

Claim:
A balance shaft assembly for a vehicle, which includes a balance shaft carrier disposed under a cylinder block and, includes an oil pan, an upper end of the oil pan being coupled to a bottom of the cylinder block, the balance shaft assembly comprising: a balance shaft protruding rearward from the balance shaft carrier and rotatably supported by the balance shaft carrier; a balance weight formed on an outer circumferential surface of the balance shaft; and a balance weight receiving portion formed at the oil pan and coupled to the balance shaft carrier to seal the balance weight therebetween; wherein the balance shaft carrier includes: a balance weight cover that is formed at a lateral side of the balance shaft, has coupling grooves formed in a substantially semicircular shape and recessed upward, is disposed above the balance weight to cover an upper portion of the balance weight and contacts the balance weight receiving portion to enclose the balance weight therebetween to seal the balance weight; and a lower coupling protrusion under the balance weight; wherein the balance weight receiving portion is formed on a bottom portion inside the oil pan and has coupling protrusions protruding upward to be fitted in the coupling grooves of the balance weight cover; and wherein the oil pan includes a coupling step behind the coupling protrusions for engaging with the lower coupling protrusion of the balance shaft carrier.