Automatic compression relief mechanism

Claim 2

In an internal combustion engine having a valve which controls flow of gas through a port communicable with the engine combustion chamber and which is biased towards a seated position, a part connected with said valve and against which a cam element is cyclically engageable to unseat the valve, and a camshaft rotatable in timed relation to the engine cycle, automatic compression relief means for causing the valve to be unseated during a predetermined portion of each engine cycle at engine cranking speeds and to occupy its seated position during said engine cycle portion at engine running speeds, said automatic compression relief means being characterized by: A. the camshaft having a radially outwardly opening cavity with flat, parallel side surfaces that extend axially of the camshaft and with a concave bottom surface curved as a cylinder segment about an axis transverse to that of the camshaft, one end portion of said cavity being near said part; B. a flyweight carried by the camshaft for rotation therewith and for movement relative thereto between defined limits in directions transverse to the camshaft axis, said flyweight being biased towards one of its said limits and being centrifugally movable towards the other one, said flyweight having, near the other end of said cavity, a camming surface which is at one distance from the camshaft axis when the flyweight is at its said one limit and is at a greater distance from the camshaft axis when the flyweight is at its said other limit; and C. an arcuate cam member received in said cavity and having surfaces mating with and slidingly engaging said surfaces of the cavity, so that the cam member is guided for slidingly rocking motion that alternately projects and retracts its opposite end portions relative to the camshaft, said cam member further having 1. its end portion adjacent to the first mentioned end of the cavity formed to provide, when projected, a cam element cooperable with said part, and 2. its other end portion cooperable with said camming surface on the flyweight whereby movement of the flyweight to its said one limit causes the first mentioned end portion of the cam member to be projected and movement of the flyweight to its other limit allows that end portion of the cam member to be retracted.

Claim 3

an integral securement portion on the other end of said arm, said securement portion being flat and perpendicular to the plane of the arm and having a hole therethrough by which it is pivoted on a pin that also pivots the flyweight for its said limited motion, said securement portion having a straight edge portion engaged along its length with a straight opposing abutment on the flyweight to constrain the flyweight to swing about said pin in unison with edgewise rotation of the securement portion of the spring member.

Claim 4

an integral securement portion on the other end of said arm, said securement portion being flat and perpendicular to the plane of the arm and having a hole therethrough by which it is pivoted on a pin that also pivots the flyweight for its said limited motion, said securement portion having a straight edge portion engaged along its length with a straight opposing abutment on the flyweight to constrain the flyweight to swing about said pin in unison with edgewise rotation of the securement portion of the spring member.

Claim 5

The internal combustion engine of claim 1, further characterized by: D. a ring-like retainer circumferentially embracing the camshaft and extending across the medial portion of the cam member to confine the latter in said cavity.

Claim 6

its other end portion cooperable with said camming surface on the flyweight whereby movement of the flyweight to its said one limit causes the first mentioned end portion of the cam member to be projected and movement of the flyweight to its other limit allows that end portion of the cam member to be retracted.

Claim 7

its other end portion cooperable with said camming surface on the flyweight whereby movement of the flyweight to its said one limit causes the first mentioned end portion of the cam member to be projected and movement of the flyweight to its other limit allows that end portion of the cam member to be retracted.

Claim 8

In an internal combustion engine having a valve movable to and from a seated position towards which it Is biased and at which it blocks flow of gas through a port communicated with the engine combustion chamber, an automatic centrifugally responsive compression relief mechanism of the type comprising a camshaft rotatable in timed relation to the engine cycle, a flyweight carried by the camshaft for rotation therewith and for movement relative thereto between defined limits in directions transverse to the camshaft axis, said flyweight being biased towards one of said limits to remain at the same at engine cranking speeds and being movable to the other limit under centrifugal force developed at engine running speeds, and a cam member carried by the camshaft for rotation therewith and movement relative thereto and having a connection with the flyweight by which motion of the flyweight to its said one limit moves the cam member to an operative position at which it unseats the valve during a predetermined portion of the engine cycle and motion of the flyweight to its said other limit enables the cam member to occupy an inoperative position in which it allows the valve to remain seated during said portion of the engine cycle, said compression relief mechanism being characterized by: A. the camshaft having a radially outwardly opening cavity with axially extending flat, parallel side surfaces and a concave bottom surface curved as a cylindrical segment about an axis transverse to that of the camshaft; B. the cam member being arcuate and confined in said cavity, and having surfaces slidingly engaged with said surfaces of the cavity whereby the cam member is guided for slidable rocking relative to the camshaft by which its opposite end portions are alternately moved to and from positions protruding radially from the camshaft, one end portion of said cam member being so formed that when in its protruding position it holds the valve unseated during said portion of the engine cycle; and C. said connection comprising cooperating camming surfaces on the flyweight and on the other end portion of the cam member whereby motion of the flyweight to its said one limit of motion moves said other end portion of the cam member away from its protruded position and motion of the flyweight to its other limit allows said other end of the cam member to move out of its protruded position.

Claim 9

In an internal combustion engine having a valve movable to and from a seated position towards which it Is biased and at which it blocks flow of gas through a port communicated with the engine combustion chamber, an automatic centrifugally responsive compression relief mechanism of the type comprising a camshaft rotatable in timed relation to the engine cycle, a flyweight carried by the camshaft for rotation therewith and for movement relative thereto between defined limits in directions transverse to the camshaft axis, said flyweight being biased towards one of said limits to remain at the same at engine cranking speeds and being movable to the other limit under centrifugal force developed at engine running speeds, and a cam member carried by the camshaft for rotation therewith and movement relative thereto and having a connection with the flyweight by which motion of the flyweight to its said one limit moves the cam member to an operative position at which it unseats the valve during a predetermined portion of the engine cycle and motion of the flyweight to its said other limit enables the cam member to occupy an inoperative position in which it allows the valve to remain seated during said portion of the engine cycle, said compression relief mechanism being characterized by: A. the camshaft having a radially outwardly opening cavity with axially extending flat, parallel side surfaces and a concave bottom surface curved as a cylindrical segment about an axis transverse to that of the camshaft; B. the cam member being arcuate and confined in said cavity, and having surfaces slidingly engaged with said surfaces of the cavity whereby the cam member is guided for slidable rocking relative to the camshaft by which its opposite end portions are alternately moved to and from positions protruding radially from the camshaft, one end portion of said cam member being so formed that when in its protruding position it holds the valve unseated during said portion of the engine cycle; and C. said connection comprising cooperating camming surfaces on the flyweight and on the other end portion of the cam member whereby motion of the flyweight to its said one limit of motion moves said other end portion of the cam member away from its protruded position and motion of the flyweight to its other limit allows said other end of the cam member to move out of its protruded position.

Claim 10

The internal combustion engine of claim 3 wherein the flyweight is biased to its said one limit of motion by means of a spring member that comprises: