Clutch assembly for a hybrid-electric aircraft propulsion system
An aircraft propulsion system includes an engine, an electric machine, a gearbox, and a propulsor. The gearbox includes an output shaft with a rotational axis, an electric machine drive gear mounted on the output shaft and driven by the electric machine, and an engine drive gear selectively couplable with the output shaft by a clutch assembly. The clutch assembly includes a coupling drive shaft mounted to the output shaft, a clutch housing mounted to the engine drive gear, and sliding clutch members moveably mounted to the clutch housing. The sliding clutch members are radially movable between inner and outer positions. In the outer position, the sliding clutch members engage the coupling drive shaft to couple the engine and output shaft. In the inner position, the sliding clutch members disengage from the coupling drive shaft to decouple the engine from the output shaft. The propulsor is driven by the output shaft.
1 . An aircraft propulsion system, comprising:
an engine;
an electric machine;
a gearbox including an output shaft, an electric machine drive gear, an engine drive gear, and a clutch assembly, the output shaft having a rotational axis, the electric machine drive gear mounted on the output shaft, the electric machine drive gear driven by the electric machine, the engine drive gear selectively couplable with the output shaft by the clutch assembly,
the clutch assembly including a coupling drive shaft, a clutch housing, and a plurality of sliding clutch members, the coupling drive shaft mounted to the output shaft, the clutch housing mounted to the engine drive gear, the plurality of sliding clutch members moveably mounted to the clutch housing, the plurality of sliding clutch members radially moveable between an outer radial position and an inner radial position, the plurality of sliding clutch members in the outer radial position engaged with the coupling drive shaft, the clutch assembly coupling the engine and the output shaft with the plurality of sliding clutch members in the outer radial position, the plurality of sliding clutch members in the inner radial position disengaged from the coupling drive shaft, the engine decoupled from the output shaft with the plurality of sliding clutch members in the inner radial position; and
a propulsor driven by the output shaft.
2 . The aircraft propulsion system of claim 1 , wherein the coupling drive shaft includes a first plurality of teeth, each of the plurality of sliding clutch members includes a second plurality of teeth, the first plurality of teeth are radially outward of the second plurality of teeth, and the second plurality of teeth are engaged with the first plurality of teeth with the plurality of sliding clutch members in the outer radial position.
3 . The aircraft propulsion system of claim 2 , wherein the first plurality of teeth and the second plurality of teeth including asymmetrical teeth.
4 . The aircraft propulsion system of claim 1 , wherein the clutch housing forms a plurality of apertures, each of the plurality of sliding clutch members includes a post disposed within a respective one of the plurality of apertures, and the post is radially moveable within the respective one of the apertures.
5 . The aircraft propulsion system of claim 4 , wherein each of the plurality of sliding clutch members includes a spring compressed between the clutch housing and the post, and the spring biases a respective one of the plurality of sliding clutch members in the inner radial position.
6 . The aircraft propulsion system of claim 1 , wherein each of the plurality of sliding clutch members includes a clutch body and a weight, the clutch body is configured to engage the coupling drive shaft with a respective one of the plurality of sliding clutch members in the outer radial position, and the weight is selectively attachable on the clutch body.
7 . The aircraft propulsion system of claim 6 , wherein the coupling drive shaft includes a first plurality of teeth, the clutch body includes a second plurality of teeth, the second plurality of teeth are engaged with the first plurality of teeth with the plurality of sliding clutch members in the outer radial position, and the weight is axially coincident with the second plurality of teeth.
8 . The aircraft propulsion system of claim 1 , wherein the gearbox further includes a bearing disposed between the output shaft and the engine drive gear, and the engine drive gear is rotatable relative to the output shaft on the bearing.
9 . The aircraft propulsion system of claim 1 , wherein the engine includes an engine output shaft, the gearbox includes an input shaft and a layshaft assembly, the engine output shaft is coupled with the input shaft, and the layshaft assembly couples the input shaft with the engine drive gear.
10 . The aircraft propulsion system of claim 1 , wherein the plurality of sliding clutch members are arranged circumferentially about the rotational axis.
11 . A method for coupling an engine of an aircraft propulsion system with a propulsor, the propulsor driven by an output shaft, an engine drive gear driven by the engine decoupled from the output shaft by a clutch assembly in a disengaged state, the method comprising:
driving rotation of the propulsor about a rotational axis with an electric machine coupled with the propulsor by the output shaft;
coupling the engine with the propulsor by controlling the engine to drive rotation of the engine drive gear about the rotational axis to configure the clutch assembly in an engaged state, the clutch assembly in the engaged state having a plurality of sliding clutch members engaged with a coupling drive shaft mounted to the output shaft, the plurality of sliding clutch members radially moveable relative to the coupling drive shaft between an outer radial position and an inner radial position, the sliding clutch members in the outer radial position engaged with the coupling drive shaft in the engaged state, the sliding clutch members in the inner radial position disengaged from the coupling drive shaft in the disengaged state, coupling the engine with the propulsor including controlling the engine to increase a rotation speed of the engine drive gear until the sliding clutch members move from the inner radial position to the outer radial position.
12 . The method of claim 11 , wherein the engine includes an engine output shaft, and the coupling the engine with the propulsor further includes controlling the engine to increase a rotation speed of the engine output shaft greater than or equal to a predetermined rotation speed corresponding to the engaged state.
13 . The method of claim 11 , wherein coupling the engine with the propulsor includes relighting the engine.
14 . The method of claim 11 , further comprising deenergizing the electric machine subsequent to coupling the engine with the propulsor.
15 . An aircraft propulsion system, comprising:
an engine;
an electric machine;
a gearbox including an output shaft, an engine drive gear, and a clutch assembly, the output shaft having a rotational axis, the electric machine coupled with the output shaft, the engine drive gear extending circumferentially about the output shaft, the engine drive gear rotatable relative to the output shaft, the engine drive gear selectively couplable with the output shaft by the clutch assembly,
the clutch assembly including a coupling drive shaft, a clutch housing, and a plurality of sliding clutch members, the coupling drive shaft mounted to the output shaft, the clutch housing mounted to the engine drive gear, the plurality of sliding clutch members moveably mounted to the clutch housing, the plurality of sliding clutch members radially moveable between an outer radial position and an inner radial position, the plurality of sliding clutch members biased in the inner radial position, the plurality of sliding clutch members in the outer radial position engaged with the coupling drive shaft, the clutch assembly coupling the engine and the output shaft with the plurality of sliding clutch members in the outer radial position, the plurality of sliding clutch members in the inner radial position disengaged from the coupling drive shaft, the engine decoupled from the output shaft with the plurality of sliding clutch members in the inner radial position; and
a propulsor driven by the output shaft.
16 . The aircraft propulsion system of claim 15 , wherein the coupling drive shaft includes a first plurality of teeth, each of the plurality of sliding clutch members includes a second plurality of teeth, the first plurality of teeth are radially outward of the second plurality of teeth, and the second plurality of teeth are engaged with the first plurality of teeth with the plurality of sliding clutch members in the outer radial position.
17 . The aircraft propulsion system of claim 15 , wherein the clutch housing forms a plurality of apertures, each of the plurality of sliding clutch members includes a post disposed within a respective one of the plurality of apertures, and the post is radially moveable within the respective one of the apertures.
18 . The aircraft propulsion system of claim 15 , wherein each of the plurality of sliding clutch members includes a clutch body and a weight, the clutch body is configured to engage the coupling drive shaft with a respective one of the plurality of sliding clutch members in the outer radial position, and the weight is selectively attachable on the clutch body.
19 . The aircraft propulsion system of claim 15 , wherein the gearbox further includes a bearing disposed between the output shaft and the engine drive gear, and the engine drive gear is rotatable relative to the output shaft on the bearing.
20 . The aircraft propulsion system of claim 15 , wherein the engine includes an engine output shaft, the gearbox includes an input shaft and a layshaft assembly, the engine output shaft is coupled with the input shaft, and the layshaft assembly couples the input shaft with the engine drive gear.