Integrated tilt/trim and steering subsystem for marine outboard engines

1. A marine outboard engine for a watercraft, comprising:

a stern bracket for mounting the marine outboard engine to the watercraft;

a tilt/trim/steering subsystem pivotably connected to the stern bracket; and

a drive unit pivotably connected to the tilt/trim/steering subsystem,

the tilt/trim/steering subsystem comprising:

a housing;

a first rotary actuator disposed in the housing for pivoting the tilt/trim/steering subsystem relative to the stern bracket about a generally horizontal tilt/trim axis; and

a second rotary actuator disposed in the housing for pivoting the drive unit relative to the tilt/trim/steering subsystem about a steering axis generally perpendicular to the tilt/trim axis.

2. The marine outboard engine of claim 1 , wherein:

the first rotary actuator includes:

a first main body having a first inside wall;

a first piston disposed within the first main body; and

a first shaft extending through the first piston, the first shaft being oriented generally parallel to the tilt/trim axis,

such that linear movement of the first piston within the first main body along the tilt/trim axis causes pivotal movement of the tilt/trim/steering subsystem relative to the stern bracket; and

the second rotary actuator includes:

a second main body having a second inside wall;

a second piston disposed within the second main body; and

a second shaft extending through the second piston, the second shaft being oriented generally parallel to the steering axis,

such that linear movement of the second piston within the second main body along the steering axis causes pivotal movement of the drive unit relative to the tilt/trim/steering subsystem.

3. The marine outboard engine of claim 2 , wherein the first and second rotary actuators are first and second hydraulic actuators.

4. The marine outboard engine of claim 3 , further comprising at least one hydraulic pump, the at least one hydraulic pump being connected to the first and second hydraulic actuators via a control valve system to cause linear movement of the first and second pistons within a corresponding one of the first and second main bodies.

5. The marine outboard engine of claim 2 , wherein the first and second main bodies are formed in the housing.

6. The marine outboard engine of claim 2 , wherein:

the first piston engages the first shaft via one of a first longitudinal spline connection and a first oblique spline connection;

the first piston engages the first main body via the other of the first longitudinal spline connection and the first oblique spline connection;

the second piston engages the second shaft via one of a second longitudinal spline connection and a second oblique spline connection; and

the second piston engages the second main body via the other of the second longitudinal spline connection and the second oblique spline connection.

7. The marine outboard engine of claim 6 , wherein:

the first piston engages the first shaft via the first longitudinal spline connection;

the first piston engages the first main body via the first oblique spline connection;

the second piston engages the second shaft via the second longitudinal spline connection; and

the second piston engages the second main body via the second oblique spline connection.

8. The marine outboard engine of claim 6 , wherein:

the first piston engages the first shaft via the first oblique spline connection;

the first piston engages the first main body via the first longitudinal spline connection;

the second piston engages the second shaft via the second oblique spline connection; and

the second piston engages the second main body via the second longitudinal spline connection.

9. The marine outboard engine of claim 2 , wherein:

the first piston engages the first shaft via one of a first longitudinal spline connection and a first pin received in a corresponding first groove;

the first piston engages the first main body via the other of the first longitudinal spline connection and the first pin received in the corresponding first groove;

the second piston engages the second shaft via one of a second longitudinal spline connection and a second pin received in a corresponding second groove; and

the second piston engages the second main body via the other of the second longitudinal spline connection and the second pin received in the corresponding second groove.

10. The marine outboard engine of claim 9 , wherein:

the first piston engages the first shaft via the first pin received in the corresponding first groove;

the first piston engages the first main body via the first longitudinal spline connection;

the second piston engages the second shaft via the second pin received in the corresponding second groove; and

the second piston engages the second main body via the second longitudinal spline connection.

11. The marine outboard engine of claim 9 , wherein:

the tilt/trim/steering subsystem pivots relative to the stern bracket at a first rate when the steering axis is substantially vertical; and

the tilt/trim/steering subsystem pivots relative to the stern bracket at a second rate greater than the first rate when the steering axis is not substantially vertical.

12. The marine outboard engine of claim 11 , wherein the first groove has:

a first segment having a first angle relative to a longitudinal axis of the first shaft; and

a first segment having a second angle relative to a longitudinal axis of the first shaft, the second angle being greater than the first angle,

such that:

the tilt/trim/steering subsystem pivots relative to the stern bracket at the first rate when the first pin engages the first segment; and

the tilt/trim/steering subsystem pivots relative to the stern bracket at the second rate when the first pin engages the second segment.