Tappet

Details Tappet Tappet

2002-02-15

2004-02-03

Denion, Thomas (Department: 3748)

Internal-combustion engines

Poppet valve operating mechanism

Tappet

C123S090490, C123S090500

Reexamination Certificate

active

06684838

ABSTRACT:

BACKGROUND
The invention concerns a tappet especially for transferring a cam or eccentric generated oscillating movement onto a sliding part such as a gas exchange valve or a pump piston, which has a circular-shaped section, which includes an outer casing for guiding in form and a base on the top, the outer side of which provides the contact area for the cam. A dome-shaped socket with a contact surface for the sliding part extends from the inner side of the base.
A tappet of this type is disclosed in FIG. 13 of the WO 95/00749. This possesses a circular-shaped section which has a one-piece dome-shaped socket extending from the topside into the interior. A separate base is secured to the topside of the socket.
The disadvantage of this construction is that the one-piece construction of the circular-shaped section with the dome-shaped socket is very difficult to manufacture, considering the current state of technology in the field. The length of the socket alone is limited by manufacturing and technical considerations. Attaching a separate base to the socket securely also presents difficulties in itself.
There is a multitude of uses, for example, in tappet bodies for valve drives in internal combustion engines or for tappets for pump pistons in injection pumps or similar devices, in which a relatively long socket is required for the interior of the tappet because of the construction proportions. But for this there is no known solution that is also economical to manufacture with the current state of technology. Indeed there are extruded bucket tappets that are more closely detailed, for example, and which are constructed in one piece with a base and a dome-shaped socket, but this socket can only feature a small and therefore insufficient length due to manufacturing, technical, and cost limitations.
SUMMARY
The object of the invention is therefore to create a tappet of the kind described above, for which the disadvantages indicated are eliminated by simple means.
By this invention, the problem is solved by manufacturing the circular-shaped section in one piece with the base, so that the dome-shaped socket is constructed as a separate component and is secured to the inner side of the base or to an inner surface of the circular-shaped section in the area of its end face near the base.
This therefore makes it economical to manufacture the “body material” for the tappet, which can then be bound easily to the socket and is adjustable with regard to height. Because of the separate construction of the dome-shaped socket, the manufacturing costs are significantly lower in comparison to the previously noted solutions, and the device can also be varied as indicated for clearance adjustment regarding height.
The socket should preferably be formed of a light-weight construction material such as sheet metal and be constructed in a hollow cylindrical manner.
Simple solutions for connecting the socket to the tappet body are the topic of further discussion below. It is recommended, for example, to furnish the socket with a ring collar in the area of its end face facing the base, and to construct this ring collar as a spring component with optional clasps. Thus, the socket can be connected by means of the spring with a latch joint to the inner surface of the circular section. As an alternative, provision can be made for connecting the ring collar by means of caulking or welding to the inner surface or the inner side of the base.
The ring collar may also be totally rejected and the end face of the socket simply caulked, welded, or soldered in the area of the base.
The thin walled construction of the socket, in accordance with requirements, guarantees a small mass for the tappet, which has an advantageous effect, for example, on the oscillating masses in the valve drive. It is also conceivable, however, to have a more massive or semi-massive socket.
Naturally, there are even more possibilities available to those skilled in the art for binding the end face of the socket or the ring collar to the tappet body, such as stamping, rolling, bonding and similar methods.


REFERENCES:
patent: 4615440 (1986-10-01), Downing
patent: 5081976 (1992-01-01), Dahm et al.
patent: 5226389 (1993-07-01), Buuck
patent: 5267538 (1993-12-01), Speil et al.
patent: 5280771 (1994-01-01), Groh et al.
patent: 5365897 (1994-11-01), Speil et al.
patent: 5664530 (1997-09-01), Ammon et al.
patent: 5870985 (1999-02-01), Bretting
patent: 5954020 (1999-09-01), Schmidt et al.
patent: 5979385 (1999-11-01), Speil et al.
patent: 4340035 (1994-06-01), None
patent: 516962 (1992-12-01), None
patent: WO 9500749 (1995-01-01), None
Patent Abstracts of Japan—Pub. No. 11324618 A Nov. 26, 1999.
Patent Abstracts of Japan—Pub. No. 2000110523 A Apr. 18, 2000.

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