Variable valve driving apparatus of internal combustion engine

Abstract

A variable valve driving apparatus of an internal combustion engine, including a drive shaft rotatably supported by a cam bracket, a drive cam disposed about an outer periphery of the drive shaft, a link arm having a first end connected to the drive cam, an oscillating cam extending from the drive cam configured to press and release a drive valve of the engine to open and close the drive valve, a link rod having a first end rotatably connected to the oscillating cam, and a control shaft rotatably supported by the cam bracket. The control shaft includes a main shaft rotatably supported by the cam bracket, an eccentric shaft spaced apart from the main shaft, and a plurality of webs connecting the main shaft and the eccentric shaft. The eccentric shaft is connected to an oscillating arm configured to transfer a drive force of the drive cam. The oscillating arm has a first portion rotatably connected to a second end of the link arm and a second portion rotatably connected to a second end of the link rod, the first and second portions being spaced apart axially with respect to the eccentric shaft. A first flow path for supplying lubricant to a first sliding contact area between the oscillating arm and the eccentric shaft is formed through the control shaft. The first flow path extends from the main shaft to the eccentric shaft through a web located beside the second portion of the oscillating arm.

1 . A variable valve driving apparatus of an internal combustion engine, comprising:
 a drive shaft rotatably supported by a cam bracket;   a drive cam disposed about an outer periphery of the drive shaft;   a link arm having a first end connected to the drive cam;   an oscillating cam extending from the drive cam configured to press and release a drive valve of the engine to open and close the drive valve;   a link rod having a first end rotatably connected to the oscillating cam; and   a control shaft rotatably supported by the cam bracket;   wherein the control shaft includes a main shaft rotatably supported by the cam bracket, an eccentric shaft spaced apart from the main shaft, and a plurality of webs connecting the main shaft and the eccentric shaft;   wherein the eccentric shaft is connected to an oscillating arm configured to transfer a drive force of the drive cam;   wherein the oscillating arm has a first portion rotatably connected to a second end of the link arm and a second portion rotatably connected to a second end of the link rod, the first and second portions being spaced apart axially with respect to the eccentric shaft; and   wherein a first flow path for supplying lubricant to a first sliding contact area between the oscillating arm and the eccentric shaft is formed through the control shaft, the first flow path extending from the main shaft to the eccentric shaft through a web located beside the second portion of the oscillating arm.   
   
   
       2 . The variable valve driving apparatus of  claim 1 , wherein the first flow path is in fluid communication with a lubricant path passing through the drive shaft. 
   
   
       3 . The variable valve driving apparatus of  claim 1 , further comprising a second flow path, wherein the second flow path supplies lubricant to a second slide contacting area between the cam bracket and the main shaft, and wherein the second flow path is in fluid communication with the first flow path to supply lubricant to the first sliding contact area between the oscillating arm and the eccentric shaft. 
   
   
       4 . The variable valve driving apparatus of  claim 1 , wherein the first flow path forms a straight line from a surface of the main shaft at the second sliding contact area to a surface of the eccentric shaft at the first sliding contact area. 
   
   
       5 . The variable valve driving apparatus of  claim 1 , wherein the plurality of webs includes a first web coupled to the eccentric shaft beside the first portion of the oscillating arm and having a first width, and a second web coupled to the eccentric shaft beside the second portion of the oscillating arm and having a second width; and wherein the second width is larger than the first width. 
   
   
       6 . The variable valve driving apparatus of  claim 1 , wherein the first flow path includes a first opening opened to the first sliding contact area at a location proximate to the second portion of the oscillating arm, and a third flow path in fluid communication with the first flow path includes a second opening opened to the first sliding contact area at a location proximate the first portion of the oscillating arm. 
   
   
       7 . The variable valve driving apparatus of  claim 1 , wherein the oscillating arm includes a first oil groove formed along the axial direction of the eccentric shaft, and wherein the first flow path is in fluid communication with the first oil groove. 
   
   
       8 . The variable valve driving apparatus of  claim 7 , wherein the oscillating arm includes a second oil groove formed along a circumferential direction of the eccentric shaft, and wherein the second oil groove is in fluid communication with the first oil groove at a first end of the first oil groove. 
   
   
       9 . The variable valve driving apparatus of  claim 8 , wherein the oscillating arm includes a third oil groove formed along a circumferential direction of the eccentric shaft, the third oil groove is in fluid communication with the first oil groove at a second end of the first oil groove, the second oil groove provides lubricant to the first sliding contact area at a location proximate to the first portion of the oscillating arm, and the third oil groove provides lubricant to the first sliding contact area at a location proximate to the second portion of the oscillating arm. 
   
   
       10 . The variable valve driving apparatus of  claim 1 , wherein the main shaft includes a tapered oil groove along a circumferential direction of the main shaft, wherein the tapered oil groove is in fluid communication with a second opening of the first flow path, and wherein a width of the tapered oil groove varies along the circumferential direction of the main shaft. 
   
   
       11 . The variable valve driving apparatus of  claim 10 , wherein the width of the tapered oil groove along the circumferential direction of the main shaft is wide at a location where the second opening of the first flow path faces the tapered oil groove when operating a drive valve in a large operating angle, and wherein a width of the tapered oil groove is narrow at a location where the second opening of the first flow path faces the tapered oil groove when operating the drive valve in a small operating angle. 
   
   
       12 . The variable valve driving apparatus of  claim 10 , wherein a width of the tapered oil groove is maximized at a location along the circumferential direction of the main shaft corresponding to the intersection of a straight line connecting a center axis of the oscillating cam, an axis of the main shaft, and an axis of the eccentric shaft; and wherein the width of the tapered oil groove becomes narrower as the oil groove proceeds away from the intersection. 
   
   
       13 . The variable valve driving apparatus of  claim 12 , wherein the second opening of the first flow path and an opening of the second flow path are aligned at the intersection. 
   
   
       14 . The variable valve driving apparatus of  claim 1 , wherein the drive valve includes a rocker arm configured to open and close a suction valve and a hydraulic lash adjuster for supporting a base of the rocker arm, wherein a third flow path supplies lubricant to the hydraulic lash adjuster from a main gallery which supplies lubricant to the first flow path, wherein the third flow path supplies lubricant from the main gallery to the hydraulic lash adjuster independently from the first flow path. 
   
   
       15 . A method of driving a valve with a variable valve driving apparatus of an internal combustion engine, comprising:
 rotatably supporting a drive shaft by a cam bracket;   disposing a drive cam about an outer periphery of the drive shaft;   connecting a first end of a link arm to the drive cam;   extending an oscillating cam from the drive cam to press and release a drive valve of the engine to open and close the drive valve;   rotatably connecting a first end of a link rod to the oscillating cam;   rotatably supporting a control shaft by the cam bracket, the control shaft including a main shaft rotatably supported by the cam bracket, an eccentric shaft spaced apart from the main shaft, and a plurality of webs connecting the main shaft and the eccentric shaft;   connecting the eccentric shaft to an oscillating arm to transfer a drive force of the drive cam, the oscillating arm having a first portion rotatably connected to a second end of the link arm and a second portion rotatably connected to a second end of the link rod, the first and second portions being spaced apart axially with respect to the eccentric shaft; and   supplying lubricant through a first flow path formed through the control shaft to a first sliding contact area between the oscillating arm and the eccentric shaft, the first flow path extending from the main shaft to the eccentric shaft through a web located beside the second portion of the oscillating arm.   
   
   
       16 . The method of  claim 15 , further comprising supplying lubricant from a lubricant path passing through the drive shaft to the first flow path. 
   
   
       17 . The method of  claim 15 , further comprising supplying lubricant through a second flow path to a second slide contacting area between the cam bracket and the main shaft, the second flow path being in fluid communication with the first flow path to supply the lubricant to the first sliding contact area between the oscillating arm and the eccentric shaft. 
   
   
       18 . The method of  claim 15 , further comprising forming the first flow path in a straight line from a surface of the main shaft at the second sliding contact area to a surface of the eccentric shaft at the first sliding contact area. 
   
   
       19 . The method of  claim 15 , further comprising coupling a first web to the eccentric shaft beside the first portion of the oscillating arm, the first web and having a first width, and coupling a second web to the eccentric shaft beside the second portion of the oscillating arm, the second web having a second width that is larger than the first width. 
   
   
       20 . The method of  claim 15 , further comprising:
 supplying lubricant through a first opening of the first flow path opened to the first sliding contact area at a location proximate to the second portion of the oscillating arm; and   supplying lubricant through a second opening of a third flow path in fluid communication with the first flow path opened to the first sliding contact area at a location proximate the first portion of the oscillating arm.   
   
   
       21 . The method of  claim 15 , further comprising supplying lubricant from the first flow path to a first oil groove formed in the oscillating arm along the axial direction of the eccentric shaft. 
   
   
       22 . The method of  claim 21 , further comprising supplying lubricant from the first oil groove to a second oil groove formed in the oscillating arm along a circumferential direction of the eccentric shaft at a first end of the first oil groove. 
   
   
       23 . The method of  claim 22 , further comprising supplying lubricant from the first oil groove to a third oil groove formed in the oscillating arm along a circumferential direction of the eccentric shaft at a second end of the first oil groove, the second oil groove providing lubricant to the first sliding contact area at a location proximate to the first portion of the oscillating arm, and the third oil groove providing lubricant to the first sliding contact area at a location proximate to the second portion of the oscillating arm. 
   
   
       24 . The method of  claim 15 , further comprising supplying lubricant to a tapered oil groove formed in the main shaft along a circumferential direction of the main shaft, the tapered oil groove being in fluid communication with a second opening of the first flow path, a width of the tapered oil groove varying along the circumferential direction of the main shaft. 
   
   
       25 . A variable valve driving apparatus of an internal combustion engine, comprising:
 a drive shaft rotatably supported by a cam bracket;   a drive cam disposed about an outer periphery of the drive shaft;   a link arm having a first end connected to the drive cam;   an oscillating cam extending from the drive cam configured to press and release a drive valve of the engine to open and close the drive valve;   a link rod having a first end rotatably connected to the oscillating cam; and   a control shaft rotatably supported by the cam bracket;   the control shaft including a main shaft rotatably supported by the cam bracket, an eccentric shaft spaced apart from the main shaft, and a plurality of webs connecting the main shaft and the eccentric shaft;   the eccentric shaft being connected to an oscillating arm configured to transfer a drive force of the drive cam;   the oscillating arm having a first portion rotatably connected to a second end of the link arm and a second portion rotatably connected to a second end of the link rod, the first and second portions being spaced apart axially with respect to the eccentric shaft; and   means for supplying lubricant to a first sliding contact area between the oscillating arm and the eccentric shaft formed through the control shaft from the main shaft to the eccentric shaft.