Internal-combustion engines – Poppet valve operating mechanism – Rocker
Reexamination Certificate
1999-07-14
2001-02-06
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
Rocker
Reexamination Certificate
active
06182626
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the priority of German Patent Application Serial No. 198 33 112.6, filed Jul. 23, 1998, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a lever-type cam follower for a valve drive of an internal combustion engine for operating at least one gas exchange valve.
U.S. Pat. No. 5,016,582, issued May 21, 1991 discloses a cam follower which is of substantially U-shaped cross section and includes two longitudinal side walls which are interconnected by a cross member. The cross member defines a valve-proximate side which has an end portion formed with a bearing surface for a gas exchange valve. An opening is formed through the cross member for passage of lubricant to the contact zone of the gas exchange valve upon the bearing surface. This conventional cam follower suffers the drawback that the bearing surface for the gas exchange valve is formed as a ball-shaped recess that increases the complexity of manufacture. Moreover, the opening for transmission of lubricant is disposed exactly in the contact zone between the gas exchange valve and the bearing surface. Thus, increased wear is experienced in this zone so that the recessed region must be reinforced.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved cam follower, obviating the afore-stated drawbacks.
This object, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a main body exhibiting a substantially U-shaped configuration and comprised of two spaced-apart side walls, extending in a longitudinal direction, and a cross member interconnecting the side walls and having a valve-proximate side which includes a substantially planar bearing surface for receiving a gas exchange valve, whereby a passageway is formed through the cross member for conduction of lubricant to a contact zone between the gas exchange valve and the bearing surface, with the passageway being disposed outside the contact zone but in immediate proximity thereto.
Through the configuration of the cross member with a substantially planar bearing surface and disposition of the passage way outside the contact zone between the gas exchange valve and the bearing surface but yet immediately adjacent thereto, a superior lubrication of the contact zone is realized, while wear, as discussed above, is no longer a factor in this contact zone. Furthermore, the cam follower according to the invention is of simple structure and therefore easy to manufacture.
According to another feature of the present invention, two side bars extend from an end face of the cam follower to effect a simple lateral guidance of the gas exchange valve. The side bars may be made, for example, through punching and bending. Suitably, the passageway for transmitting lubricant to the contact zone of the gas exchange valve upon the bearing surface is provided by an opening in the area of at least one of the side bars whereby the opening at least partially intersects in prolongation the side bar outside the immediate contact zone.
Each side bar may have a substantially arched configuration on the valve-proximate side of the cross member and defines an end which approaches the valve-proximate side. Alternatively, each side bar may also abut the valve-proximate side of the cross member, whereby the opening forming the passageway also intersects in prolongation the side bar and is fluidly connected via a recess, provided in the side bar or valve-proximate side of the cross member for transmitting lubricant into the direction toward the contact zone to realize an appropriate lubrication in this region.
The valve-proximate side of the cross member may be so positioned as to face away from the side walls of the main body. However, it is certainly within the scope of the present invention to position the valve-proximate side between the side walls, as well.
For reasons of cost-efficiency, the cam follower may be made of sheet steel. However, other material may also be used, such as lightweight materials, plastic materials, etc. The cam follower may also be made through other shaping processes such as casting.
According to still another feature of the present invention, the lubricating opening may be formed as bore which may have a chamfer at the valve-proximate side. The chamfer serves as “collection funnel” for oil spray (lubricant) in the area of the cylinder head, or as small lubricant reservoir. Although the provision of one opening is sufficient, it may be suitable to provide two opening for each contact zone between a gas exchange valve and the bearing surface. The passageway may also be configured as oblong hole or the like, thereby realizing a particularly great amount of lubricant being transmitted.
The cam follower may be made as rocker lever or finger lever, and may be configured for operation of several gas exchange valves acting in a same fashion.
REFERENCES:
patent: 1699659 (1929-01-01), Fagan
patent: 2338726 (1944-01-01), Leake
patent: 2345822 (1944-04-01), Leake
patent: 3289657 (1966-12-01), Winter, Jr.
patent: 3359959 (1967-12-01), Rose
patent: 4614171 (1986-09-01), Malhotra
patent: 5016582 (1991-05-01), Mills
patent: 5678459 (1997-10-01), Motohashi et al.
patent: 5720245 (1998-02-01), Calka
patent: 5730093 (1998-03-01), Calka et al.
patent: 5819694 (1998-10-01), Trutescu et al.
patent: 6035820 (2000-03-01), Engelhardt
patent: 6062184 (2000-05-01), Engelhardt
patent: 195 43 657 A1 (1997-05-01), None
Geus Hubert
Hertrich Steffen
Feiereisen Henry M.
Ina Walzlager Schaeffler OHG
Patel Vinod D.
Walberg Teresa
LandOfFree
Lever-type cam follower for a valve drive of an internal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lever-type cam follower for a valve drive of an internal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lever-type cam follower for a valve drive of an internal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2593668