US 6,439,188 B1Granted

Four cycle four cylinder in-line engine with rotors of a supercharging device used as balance shafts

AssigneeBrunswick Corporation

InventorRichard A. Davis

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Abstract

A four cycle four cylinder in-line internal combustion engine is provided with a housing structure that contains two shafts which rotate in opposite directions to each other and at the same rotational velocity. Pairs of counterweights are attached to the two shafts in order to provide a counterbalance force which is generally equal to an opposite from the secondary shaking force which results from the reciprocal movement of the pistons of the engine. The first and second shafts are rotors of a supercharging device, such as a Roots blower. The rotational speed of the first and second shafts is twice that of the rotational speed of the crankshaft of the engine and the provision of counterweights on the first and second shafts balances the secondary forces caused by the reciprocal motion of the piston in the engine.

Claims25

Dependent claims

An engine, comprising:

a crankshaft supported for rotation about a crankshaft axis;
a plurality of pistons connected to said crankshaft, each of said plurality of pistons being disposed for reciprocating movement within an associated one of a plurality of cylinders of said engine;
a first shaft supported for rotation about a first axis of rotation at a first rotational velocity in a first rotational direction, said first shaft having a first center of gravity which is radially displaced from said first axis of rotation by a first preselected amount;
a second shaft supported for rotation about a second axis of rotation at a second rotational velocity in a second rotational direction, said second shaft having a second center of gravity which is radially displaced from said second axis of rotation by a second preselected amount, said first and second axes of rotation being generally parallel to said crankshaft axis, said first and second rotational directions being opposite to each other, said first and second rotational velocities each being generally equal to a preselected multiple of the rotational velocity of said crankshaft;
and
a housing structure attached to said engine, said first and second shafts being supported by said housing structure for rotation within said housing structure, said housing structure being removably attached to said engine, said housing structure containing a supercharging device.

3 more elements

An engine of an outboard motor, comprising:

a crankshaft supported for rotation about a vertical axis;
a plurality of pistons connected to said crankshaft, each of said plurality of pistons being disposed for reciprocating movement within an associated one of a plurality of cylinders of said engine;
a first shaft supported for rotation about a first axis of rotation at a first rotational velocity in a first rotational direction, said first shaft having a first center of gravity which is radially displaced from said first axis of rotation by a first preselected amount;
a second shaft supported for rotation about a second axis of rotation at a second rotational velocity in a second rotational direction, said second shaft having a second center of gravity which is radially displaced from said second axis of rotation by a second preselected amount, said first and second axes of rotation being generally parallel to said vertical axis, said first and second rotational directions being opposite to each other, said first and second rotational velocities each being generally equal to a preselected multiple of the rotational velocity of said crankshaft, said first and second shafts being connected in torque transmitting association with said crankshaft, said first and second shafts being first and second rotors, respectively, of a supercharging device;
and
a housing rigidly attached to said engine, said first and second shafts being supported by said housing for rotation within said housing.

3 more elements

Dependencies are inferred from the claim text.