1. Field of the Invention
The present invention relates to a system for operating poppet-type cylinder valves of a reciprocating internal combustion engine, so as to selectively control the duration of the valve opening events.
2. Disclosure Information
Variable valve duration control devices have been the subject of much invention during the past few decades. U.S. Pat. No. 5,373,818 discloses but one example of such inventive activity. The '818 patent describes a variable duration valve operating system having at least one embodiment which is useful with bucket tappets, but which is not useful for application to roller finger followers. A second embodiment may be employed with a finger follower, but in the context of an operating system having high inertia, and therefore, unacceptably slow system response time.
Other types of variable valve operating devices have been used, including such systems as axially shiftable camshafts, cam timing control devices, electromagnetically actuated valves, and yet other devices. The present system is readily usable with finger follower valve actuation systems and allows the control of valve events extending from no valve opening whatsoever (i.e., valve deactivation) to a maximum opening.
A poppet valve operating system for an internal combustion engine includes a poppet valve, a finger follower for actuating the poppet valve, and an intermediate rocker for actuating a finger follower. The intermediate rocker has a control surface formed therein. A drive cam, powered by a crankshaft of the engine, actuates the intermediate rocker by providing input force tending to move the intermediate rocker translationally. A selectively positioned control roller which bears upon the control surface of the intermediate rocker controls the lift of the poppet valve by selectively causing the motion of the intermediate rocker to be at least partially rotational. The control roller is positionable such that the intermediate rocker has a range of movement extending from purely translational movement, which does not cause the finger follower to lift the poppet valve, to a range of mixed translational and rotational trajectories causing the finger follower to lift the poppet valve to varying degrees. The finger follower has a first end contacting the poppet valve, and a second end operatively connected with a hydraulic lash adjuster extending between a cylinder head of the engine and the second end of the finger follower.
According to another aspect of the present invention, a method for operating a poppet cylinder valve in an internal combustion engine includes the steps of providing a drive cam powered by a crankshaft to the engine, providing an intermediate rocker actuated by the drive cam, and providing a finger follower for actuating a poppet valve, with the finger follower being actuated by the intermediate rocker. Finally, the present method includes the step of providing a control roller for interacting with a control surface incorporated as part of the intermediate rocker, so as to determine the lift of a poppet valve actuated by the finger follower by controlling the rotational movement of the intermediate rocker resulting from actuation of the intermediate rocker by the drive cam.
The previously described control roller has a number of operating positions including at least a first position in which the intermediate rocker moves purely translationally, and a second position, in which the intermediate rocker moves both translationally and rotationally.
The present valve operating system offers the advantage of lower operating inertia as compared with known designs, as well as smaller package volume. Further, the present system may be employed with roller finger follower technology.
Other advantages, as well as objects and features of the present invention, will become apparent to the reader of this specification.
As shown in various figures, the present cylinder valve operating system, 10, is intended for use with poppet valves 14, which are mounted within cylinder head 18 of an engine. Valves 14 are returned to their closed positions by means of valve springs 16. Each of valves 14 is actuated by means of a finger follower, 20, which has a first end in contact with valve 14 and a second end in contact with lash adjuster 28, which is mounted to cylinder head 18. Finger follower 20 has a roller, 24, which contacts intermediate rocker 30.
Intermediate rocker 30 is biased into contact with drive cam 40 by means of compression spring 62. Alternatively, a torsion spring (not shown) could be used for this purpose. Intermediate rocker 30 rotatably actuates finger follower 20 as drive cam 40, which is mounted upon camshaft 44, and driven either by a crankshaft or other rotating member of the engine (not shown), pushes upon rocker roller 32, thereby moving intermediate rocker 30 translationally. Camshaft 44 and intermediate rocker 30 are mounted so that the motion imparted by camshaft 44 and drive cam 40 to intermediate rocker 30 is purely translational. This translational movement is controllably transformed into rotational movement of intermediate rocker 30 by control roller 48, which is mounted upon support shaft 50. In essence, intermediate rocker 30 pivots about an instantaneous contact point existing between control surface 34 and the outer diametral surface of control shaft 58. Support shaft 50 is carried within control slot 54 formed in cylinder head 18c. Alternatively, support shaft 50 may be carried within a slotted member rigidly attached to cylinder head 18.
Control slot 54 permits translational movement of support shaft 50. This translational movement is produced by control cam 56 which is mounted upon control shaft 58. As control shaft 58 is rotated, control cam 56 displaces control shaft 50 within slot 54, so as to move control roller 48 to a new operating position. In general, when control roller 48 is moved closer to camshaft 44, valve lift will be increased because control roller 48 will be operating on rocker ramp 34, which is a control surface formed in intermediate rocker 30, in a position so that the motion depicted in
In
Although the present invention has been described in connection with particular embodiments thereof, it is to be understood that various modifications, alterations, and adaptations may be made by those skilled in the art without departing from the spirit and scope of the invention set forth in the following claims.
Number | Name | Date | Kind |
---|---|---|---|
5078102 | Matsumoto | Jan 1992 | A |
5373818 | Unger | Dec 1994 | A |
5988125 | Hara et al. | Nov 1999 | A |
5996540 | Hara | Dec 1999 | A |
6019076 | Pierik et al. | Feb 2000 | A |
6041746 | Takemura et al. | Mar 2000 | A |
6318317 | Hubschle | Nov 2001 | B1 |
6354255 | Methley et al. | Mar 2002 | B1 |
6360705 | Raghavan et al. | Mar 2002 | B1 |
6378474 | Pierik | Apr 2002 | B1 |
6425357 | Shimizu et al. | Jul 2002 | B2 |
6491008 | Zubeck | Dec 2002 | B1 |
Number | Date | Country |
---|---|---|
0717174 | Jun 1996 | EP |
0780547 | Jun 1997 | EP |
WO 9836157 | Aug 1998 | WO |