Balance shaft module having variable displacement oil pump

Abstract

A balance shaft module having a variable capacity hydraulic pump may include a first balance shaft that receives torque from an engine and a first unbalance mass is formed, a second balance shaft that receives torque from the first balance shaft through a connection gear, and a hydraulic pump that suctions and discharges oil by the rotation of the second balance shaft and varies its capacity depending on oil pressure discharged.

What is claimed is: 
     
         1 . A balance shaft module having a variable capacity hydraulic pump, comprising:
 a first balance shaft that receives torque from an engine and a first unbalance mass is formed;   a second balance shaft that receives torque from the first balance shaft through a connection gear; and   a hydraulic pump that draws and discharges oil by the rotation of the second balance shaft and varies a pump capacity depending on oil pressure discharged.   
     
     
         2 . The balance shaft module having a variable capacity hydraulic pump of  claim 1 , wherein the first balance shaft and the second balance shaft rotate two times faster than an engine. 
     
     
         3 . The balance shaft module having a variable capacity hydraulic pump of  claim 1 , wherein the variable capacity hydraulic pump includes:
 an inner rotor that is disposed to be rotated by the second balance shaft, a vane groove is formed toward a central direction on an exterior circumference, and the vane grooves have a predetermined distance from each other in a rotating direction;   a vane, one end portion of which is inserted into the vane groove, and an other end portion of which protrudes from an exterior circumference of the inner rotor;   an outer ring that a suction interior circumference, a compression interior circumference, and a discharge interior circumference are sequentially formed on an interior circumference thereof, covers an outer side in such a way that the inner rotor and the vane is disposed therein, and one side of an outer side thereof rotates based on a pivot in such a way that an eccentric amount with the inner rotor is controlled;   an inner ring that an exterior circumference thereof supports one end of the vane such that an other end of the vane contacts an interior circumference of the outer ring; and   an elastic member that elastically supports the outer ring so as to variably control the eccentric amount of the outer ring and the inner rotor such that the outer ring rotates based on the pivot.   
     
     
         4 . The balance shaft module having a variable capacity hydraulic pump of  claim 3 , wherein a thickness is formed in a length direction of the second balance shaft,
 the outer ring has a first thickness, the suction interior circumference has a second thickness, the compression interior circumference has a third thickness, and the discharge interior circumference has a fourth thickness, and   the second thickness is smaller than the first thickness, and the fourth thickness is smaller than the third thickness.   
     
     
         5 . The balance shaft module having a variable capacity hydraulic pump of  claim 4 , wherein the first thickness is equal to the third thickness. 
     
     
         6 . The balance shaft module having a variable capacity hydraulic pump of  claim 4 , wherein the second thickness is equal to the fourth thickness. 
     
     
         7 . The balance shaft module having a variable capacity hydraulic pump of  claim 3 , wherein a vane angle that is formed between the vanes that are arranged in a rotating direction of the inner rotor is smaller than a compression portion angle of the compression interior circumference. 
     
     
         8 . The balance shaft module having a variable capacity hydraulic pump of  claim 3 , further comprising a housing that contacts side surface of the outer ring and the inner rotor,
 wherein a plane compression portion surface is formed to correspond to the compression interior circumference of the outer ring,   a suction chamber is formed at one side of the compression portion surface to correspond to the suction interior circumference of the outer ring, and   a discharge chamber is formed at an other side of the compression portion surface to correspond to the discharge interior circumference of the outer ring.   
     
     
         9 . The balance shaft module having a variable capacity hydraulic pump of  claim 3 , wherein a suction inner surface through which oil is sucked is formed at an inner side of the outer ring in a rotating direction of the vane,
 a discharge inner surface through which oil is discharged between the discharge inner circumference is formed in a rotating direction of the vane,   a distance between the suction interior circumference and the suction inner surface is gradually reduced in a rotating direction of the vane, and a distance between the discharge interior circumference and the discharge inner surface is gradually increased in a rotating direction of the vane.