Internal-combustion engines – Adjustable combustion chamber – Piston in head adjusted
Reexamination Certificate
2001-12-10
2003-05-13
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Adjustable combustion chamber
Piston in head adjusted
C123S197300
Reexamination Certificate
active
06561142
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates in general to reciprocating internal combustion engines of a type that is capable of varying a compression ratio during operation thereof. Particularly, the present invention relates to the reciprocating internal combustion engines of a multi-link type wherein each piston is connected to a crankshaft through a plurality of links, and more particularly to a crank mechanism of such internal combustion engines.
2. Description of Related Art
The paper “MTZ Motortechnische Zeitschrift 58” issued in 1997 in Germany shows in pages 706 to 711 an internal combustion engine of the above-mentioned multi-link type. In addition, Laid-open Japanese Patent Application (Tokkai) 2000-73804 shows such engine. In order to clarify the task of the present invention, a crank mechanism employed in the engine of 2000-73804 will be briefly described with reference to FIG.
16
.
In
FIG. 16
, denoted by numeral
51
is a cylinder of the engine. A piston
3
is slidably received in the cylinder
3
. An upper link
52
extends downward from a piston pin
5
of the piston
3
. Denoted by numeral
56
is a lower link which is pivotally disposed on a crank pin
55
of a crankshaft
54
. The crankshaft
54
comprises a plurality of paired counterweights
60
. Each pair of the counterweights
60
have the crank pin
55
at diametrically opposed ends (viz., crank webs) thereof. The lower link
56
has one arm pivotally connected to a lower end of the upper link
52
through a first connecting pin
53
. The lower link
56
has another arm pivotally connected to a lower end of a control link
38
through a second connecting pin
57
. An upper end of the control link
38
is connected to an eccentric cam
59
, so that a rotational movement of the eccentric cam
59
changes the position of the control link
38
. With this changing, the top dead center (TDC) of the piston
3
changes and thus compression ratio of the engine changes.
SUMMARY OF INVENTION
In the crank mechanism of the publication, under operation of the engine, the paired counterweights
60
are rotated about an axis of the crankshaft
54
within a zone defined between the first and second connecting pins
53
and
57
. For achieving such rotation of the counterweights
60
without inducing interference of the first and second connecting pins
53
and
58
with the counterweights
60
, it is inevitably necessary to cause the lower link
56
to have an elongated and bulky structure, as shown, which however brings about a bulky structure of the entire construction of the crank mechanism. Furthermore, in the crank mechanism of the publication, due to its inevitable construction, it is difficult to provide the first and second connecting pins
53
and
57
with a satisfied bearing capacity.
It is therefore an object of the present invention to provide a crank mechanism of a reciprocating internal combustion engine of a multi-link type, which can provide the connecting pins with a satisfied bearing capacity irrespective of a compact construction of the crank mechanism.
Another object of the present invention is to provide a crank mechanism of such reciprocating internal combustion engine, which can provide the connecting pins with a satisfied bearing capacity and provide the counterweights with a satisfied inertial moment.
According to a first aspect of the present invention, there is provided a crank mechanism of a reciprocating internal combustion engine having. The crank mechanism comprises a crankshaft including paired crank webs with first end portions connected through a crank pin, and paired counterweights integral with second end portions of the paired crank webs, the paired counterweights having projected inner surfaces which protrude toward each other defining a given space therebetween, and a link mechanism including a plurality of links which are arranged to convert a reciprocating motion of the piston to a rotational motion of the crankshaft, a given one of the links being pivotally connected to other links through link connecting portions and swingably disposed on the crank pin so that upon rotation of the crankshaft, a peripheral portion of the given link passes through the given space, wherein at least one of the link connecting portions is placed within an imaginary circle which would be described as being centered about an axis of said crank pin and having a radius substantially equal to the distance between the radially innermost part of the projected inner surfaces of the paired counterweights and the center of the crank pin.
According to a second aspect of the present invention, there is provided a crank mechanism of a reciprocating internal combustion engine having a piston. The crank mechanism comprises a crankshaft including paired crank webs with first end portions connected through a crank pin, and paired counterweights integral with second end portions of the paired crank webs, the paired crank webs having mutually facing surfaces which define therebetween a given space; a link mechanism including a plurality of links which are arranged to convert a reciprocating motion of the piston to a rotational motion of the crankshaft, a given one of the links being pivotally connected to other links through link connecting portions and swingably disposed on the crank pin so that upon rotation of the crankshaft, a peripheral portion of the given link passes through the given space; and recesses respectively formed in the mutually facing surfaces of the paired crank webs, the recesses being positioned and sized to permit at least one of the link connecting portions to pass therebetween upon swinging of the given link about an axis of the crank pin.
REFERENCES:
patent: 4475495 (1984-10-01), Lydell
patent: 4517931 (1985-05-01), Nelson
patent: 4890588 (1990-01-01), Tillman
patent: 6202622 (2001-03-01), Raquiza, Jr.
patent: 6352057 (2002-03-01), Drecq
patent: 2001/0017112 (2001-08-01), Moteki et al.
patent: 2000-73804 (2000-03-01), None
U.S. patent application Ser. No. 09/899,038, Moteki et al., filed Jul. 6, 2001.
U.S. patent application Ser. No. 09/961,240, Moteki, filed Sep. 25, 2001.
Von Christoph Bollig et al. “Kurbeltrieb für variable Verdichtung”, MTZ Motortechnische Zeitschrift 58 (1997), pp. 706-711.
Aoyama Shunichi
Fujimoto Hiroya
Hiyoshi Ryousuke
Moteki Katsuya
Benton Jason
Kamen Noah P.
Nissan Motor Co,. Ltd.
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