Patent Description:
An electric motor system includes an electric motor connectable to an ancillary component, such as a propulsion system drive train. Under certain operating conditions it is desired to disconnect the electric motor from the ancillary component. To achieve this, the electric motor includes a disconnect shaft which is selectably engageable with an output shaft to disengage the electric motor from the ancillary component.

In order to reduce the overhung moment to the electric motor, the largest and heaviest components are positioned closest to the mounting flange, or drive end. Smaller and lighter components then must be positioned farther from the mounting flange. In order to connect the small components, such as the disconnect shaft, to the drive end, the diameter of the disconnect shaft is reduced, thus resulting in a smaller engagement portion on the ramp shaft for the plunger. <CIT> relates to a disconnect mechanism. <CIT> relates to a disconnect coupling. <CIT> relates to a decoupler shaft. <CIT> relates to a disconnect plunger.

In one embodiment, a disconnect mechanism to disconnect an electric machine from an ancillary component includes a ramp shaft connected to a disconnect shaft of the electric machine, and connected to the ancillary component, such that when connected to the ancillary component the disconnect shaft transmits rotational energy between the electric motor and the ancillary component. The ramp shaft includes a disconnect feature. A plunger is selectably engageable with the disconnect feature to disconnect the ramp shaft from the disconnect shaft. The disconnect feature includes a drop-in window for initial engagement with the plunger, and a ramp surface extending in a circumferential direction from the drop in window at an acute angle relative to the drop in window. Engagement of the plunger with the ramp surface urges movement of the ramp shaft in an axial direction away from the disconnect shaft to disconnect the ramp shaft from the disconnect shaft.

Additionally or alternatively, in this or other embodiments the acute angle is in the range of <NUM> degrees to <NUM> degrees.

Additionally or alternatively, in this or other embodiments the acute angle is <NUM> degrees.

The drop-in window extends in the range of <NUM> degrees to <NUM> degrees circumferentially around the ramp shaft.

Additionally or alternatively, in this or other embodiments the drop-in window extends <NUM> degrees circumferentially around the ramp shaft.

Additionally or alternatively, in this or other embodiments the drop in window is defined perpendicular to a central axis of rotation of the ramp shaft.

Additionally or alternatively, in this or other embodiments the drop-in window extends partially circumferentially about the ramp shaft, and the ramp surface extends about the remainder of the ramp shaft circumference.

Additionally or alternatively, in this or other embodiments the ramp shaft is connected to the disconnect shaft at a first axial end of the ramp shaft, and the disconnect feature is disposed at a second axial end of the ramp shaft.

Additionally or alternatively, in this or other embodiments the plunger is engageable with the ramp shaft via operation of a solenoid operably connected to the plunger.

In another embodiment, an electric machine system includes an electric machine and an ancillary component selectably disconnectable from the electric machine ancillary component. A disconnect mechanism disconnects the electric machine from the ancillary component and includes a ramp shaft and disconnect shaft of the electric machine selectable connectible to an ancillary component and connected to the ancillary component, such that when connected to the ancillary component, the disconnect shaft transmits rotational energy between the electric motor and the ancillary component. The ramp shaft includes a disconnect feature. A plunger is selectably engageable with the disconnect feature to disconnect the disconnect shaft from the ancillary component. The disconnect feature includes a drop-in window for initial engagement with the plunger, and a ramp surface extending in a circumferential direction from the drop in window at an acute angle relative to the drop in window. Engagement of the plunger with the ramp surface urges movement of the ramp shaft in an axial direction away from the ancillary component to disconnect the disconnect shaft from the ancillary component.

In this or other embodiments the drop-in window extends in the range of <NUM> degrees to <NUM> degrees circumferentially around the ramp shaft.

Additionally or alternatively, in this or other embodiments the electric machine is an electric motor.

Additionally or alternatively, in this or other embodiments the ancillary component is a propulsion system drive train.

Referring to <FIG>, illustrated is a cross-sectional view of an embodiment of an electric motor system <NUM>. The electric motor system <NUM> includes an electric machine, such as an electric motor <NUM> selectably connectible to and disconnectable from an ancillary component <NUM>, such as a propulsion system drive train or other component. The ancillary component <NUM> includes an input shaft <NUM> through which rotational energy from the electric motor <NUM> to the ancillary component <NUM>. More particularly, the input shaft <NUM> is connected to the disconnect shaft <NUM> via a dog tooth clutch <NUM>.

The electric machine <NUM> includes a rotor <NUM> located at and rotatable about a central axis <NUM>. A stator <NUM> including a plurality of conductive windings <NUM> is located radially outboard of the rotor <NUM> defining a radial air gap <NUM> between the rotor <NUM> and the stator <NUM>. In operation, when the stator <NUM> is electrically energized, magnetic interaction between the stator <NUM> and the rotor <NUM> across the air gap <NUM> urges rotation of the rotor <NUM> about the central axis <NUM>. The rotor <NUM> includes a rotor shaft <NUM>, and a disconnect shaft <NUM> located radially inboard of the rotor shaft <NUM>. The disconnect shaft <NUM> is operably connected to the rotor shaft <NUM> by, for example a spline connection so that the disconnect shaft <NUM> rotates together with the output shaft <NUM>, which rotates with the rotor <NUM> about the central axis <NUM>. A resolver <NUM> is located radially outboard of the output shaft <NUM> and is utilized to determine an angular position of the rotor <NUM>.

Referring now to <FIG>, a spline connection <NUM> is defined between a disconnect shaft outer surface <NUM> and the rotor shaft inner surface <NUM> to connect the disconnect shaft <NUM> and the rotor shaft <NUM>. A threaded connection <NUM> is defined between the disconnect shaft <NUM> and the ramp shaft <NUM> to operable connect the ramp shaft <NUM> to the disconnect shaft <NUM>. The ramp shaft <NUM> is selectably interactive with a plunger <NUM>, which results in disconnection of the ramp shaft <NUM> and disconnect shaft <NUM> at the dog clutch connection <NUM>. The resolver <NUM> surrounds the rotor shaft <NUM>, and thus limits an outer diameter of the rotor shaft <NUM> as well as those of the disconnect shaft <NUM> and the ramp shaft <NUM>.

Referring now to <FIG>, the ramp shaft <NUM> is illustrated in more detail. The ramp shaft <NUM> includes threads <NUM> at the first ramp shaft end <NUM> and a circumferentially extending ramp portion <NUM> at the second ramp shaft end <NUM>. The ramp portion <NUM> includes a drop-in window <NUM>, shown in <FIG>, which is defined by a circumferentially-extending drop-in surface <NUM>, and a ramp <NUM>, shown in <FIG>, which is defined by a circumferentially-extending ramp surface <NUM>. The drop-in surface <NUM> extends in a radial direction, perpendicular to the central axis <NUM>. The ramp surface <NUM> circumferentially abuts the drop-in surface <NUM> and extends at an acute ramp angle <NUM> from the drop-in surface <NUM> toward the rotor <NUM>, relative to the drop-in surface <NUM>.

Shown in <FIG> is a rollout view of the drop-in window <NUM> and the ramp <NUM>. The drop-in surface <NUM> extends circumferentially partially around the ramp shaft <NUM>, and the ramp surface <NUM> extends the remainder of the circumference around the ramp shaft <NUM>. In some embodiments, the drop-in surface <NUM> extends circumferentially over a drop-in angle <NUM> in the range of <NUM> to <NUM> degrees around the ramp shaft <NUM>, while the ramp surface <NUM> extends the remaining circumferential distance around the ramp shaft <NUM>. In one embodiment, the drop-in surface <NUM> extends <NUM> circumferential degrees around the ramp shaft <NUM>, while the ramp surface <NUM> extends the remaining circumferential distance around the ramp shaft <NUM>. The ramp surface <NUM> extends at a constant and continuous ramp angle <NUM> the remaining circumferential distance to meet the meet the drop-in window <NUM>. In some embodiments, the ramp angle <NUM> is in the range of <NUM> degrees to <NUM> degrees, while in one embodiment the ramp angle is <NUM> degrees.

Referring now to <FIG>, illustrated is the operation of the ramp shaft <NUM> and engagement with the plunger <NUM> to disconnect the ramp shaft <NUM> and disconnect shaft <NUM> from the ancillary component <NUM>. The surrounding structure is omitted from the FIGs. for the sake of clarity. The plunger <NUM> is shown in a disengaged position relative to the ramp shaft <NUM> in <FIG>. The ramp shaft <NUM> is connected to the disconnect shaft <NUM> (shown in <FIG>) and is rotating with the rotor <NUM> of the electric machine <NUM> in a rotation direction <NUM>. When it is desired to disconnect the electric motor <NUM> from the ancillary component <NUM>, the plunger <NUM> is activated by operation of an actuator <NUM>, such as a solenoid or other actuator, or by a spring <NUM>. In one embodiment, a solenoid pin engages the plunger <NUM> and holds the plunger <NUM> in the disengaged position. When the solenoid is energized, the solenoid pin retracts, thus disengaging from the plunger <NUM>. Activation of the plunger <NUM> urges the plunger <NUM> toward the ramp shaft <NUM> in a radial direction <NUM> relative to the central axis <NUM>. As the ramp shaft <NUM> rotates, the plunger <NUM> engages with the ramp shaft <NUM> at the drop-in window <NUM>. Referring now to <FIG>, as the ramp shaft <NUM> continues to rotate, the plunger <NUM> engages the ramp surface <NUM>, and continued rotation of the ramp shaft <NUM> with the plunger <NUM> engaged to the ramp surface <NUM> urges movement of the ramp shaft <NUM> in an axial direction <NUM> thus disconnecting the electric motor <NUM> from the ancillary component <NUM>.

The ramp shaft <NUM> with the drop-in window <NUM> and ramp surface <NUM> as disclosed herein allows for usage with reduced diameter disconnect shafts and off the shelf components, such as the resolver <NUM> and the plunger <NUM>, and allows for configurations of electric motor <NUM> with reduced overhung moment, and further reduces plunger <NUM> stresses by allowing for larger diameter plunger <NUM> due to increased circumferential width of the drop-in window <NUM>.

Claim 1:
A disconnect mechanism to disconnect an electric machine from an ancillary component, comprising:
a ramp shaft (<NUM>) connected to a disconnect shaft (<NUM>) of the electric machine, and connected to the ancillary component, such that when connected to the ancillary component the disconnect shaft (<NUM>) transmits rotational energy between the electric motor and the ancillary component, the ramp shaft (<NUM>) including a disconnect feature; and
a plunger (<NUM>) selectably engageable with the disconnect feature to disconnect the ramp shaft from the disconnect shaft;
wherein the disconnect feature includes:
a drop-in window (<NUM>) for initial engagement with the plunger (<NUM>); and
a ramp surface (<NUM>) extending in a circumferential direction from the drop in window (<NUM>) at an acute angle relative to the drop in window, such that engagement of the plunger (<NUM>) with the ramp surface (<NUM>) urges movement of the ramp shaft (<NUM>) in an axial direction away from the disconnect shaft (<NUM>) to disconnect the ramp shaft (<NUM>) from the disconnect shaft (<NUM>); characterized in that:
the drop-in window (<NUM>) extends in the range of <NUM> degrees to <NUM> degrees circumferentially around the ramp shaft (<NUM>).