Deployable and retractable shock strut
A shock strut for a vehicle includes a housing with a through channel and a motor mount, and a motor fixed to the housing. The cylinder of a shock strut is configured to define a lead screw on its outer surface. The cylinder extends through the housing. The piston of the shock strut is attached to a ground engaging assembly. A gear nut rotatably mounted in the housing threadably engages the threaded cylinder, and is configured to be driven by the motor. The housing is attached to the vehicle, and the gear nut is controllably rotated to extend and retract the shock strut. A sensor provided on the assembly monitors the position of the shock strut. A torsion link assembly reacts rotational forces on the cylinder.
1. A shock absorbing strut for a vehicle comprising:
a housing defining a through channel and including a motor mount, wherein the housing is configured to be pivotably mounted to the vehicle;
a motor fixed to the motor mount and configured to controllably drive a shaft and a pinion gear mounted on the shaft;
a shock absorber comprising a piston pivotably connected to a ground engaging assembly, and a cylinder that slidably receives the piston, wherein an outer surface of the cylinder comprises a screw thread, and further wherein the cylinder extends through the housing through channel;
a geared nut having a central aperture that threadably engages the cylinder screw thread and a peripheral gear portion that is driveably engaged by the pinion gear; and
upper and lower bearing assemblies rotatably supporting the geared nut in the housing;
wherein the motor is configured to rotate the geared nut in the housing such that the cylinder moves axially.
2. The shock absorbing strut of claim 1 , wherein the housing is pivotably mounted to the vehicle with a pair of oppositely disposed trunnion pins.
3. The shock absorbing strut of claim 1 , wherein the motor is an electric motor, and further comprises a connection member for receiving and transmitting control signals to and from the motor.
4. The shock absorbing strut of claim 3 , wherein the electric motor comprises a brushless DC motor.
5. The shock absorbing strut of claim 3 , further comprising a sensor configured to detect an extension position of the strut, and to provide sensor data to a controller.
6. The shock absorbing strut of claim 5 , wherein the sensor is configured to monitor the net number of rotations of the geared nut.
7. The shock absorbing strut of claim 1 , wherein the ground engaging assembly comprises a trailing arm assembly having a first mounting portion that pivotably connects to the piston, and a second mounting portion comprising a pivot pin spaced apart from the first mounting portion.
8. The shock absorbing strut of claim 7 , wherein the ground engaging assembly further comprises an axle rotatably mounted in the trailing arm assembly, and a plurality of wheels mounted on the axle.
9. The shock absorbing strut of claim 7 , further comprising a torsion link assembly connecting the piston to the cylinder such that the piston can move axially with respect to the cylinder but is prevented from moving rotationally with respect to the cylinder.
10. The shock absorbing strut of claim 1 , wherein the shock absorbing strut comprises a portion of a landing gear for an aircraft.
11. The shock absorbing strut of claim 1 wherein the screw thread is a trapezoidal thread.
12. The shock absorbing strut of claim 1 , wherein the first and second bearing assemblies comprise single row deep groove ball bearings.
13. A method of extending and retracting a shock absorbing strut mounted to a vehicle, wherein the shock absorbing strut comprises:
a housing defining a through channel and including a motor mount attached to the vehicle;
a shock absorber comprising a piston pivotably connected to a ground engaging assembly, and a cylinder that slidably receives the piston, an outer surface of the cylinder having a screw thread, wherein the cylinder extends through the housing through channel;
a geared nut having a central aperture that threadably engages the cylinder screw thread and a peripheral gear portion;
a motor fixed to the motor mount and configured to drive a pinion gear that engages the peripheral gear portion of the geared nut;
the method comprising:
sensing the location of the cylinder within respect to the housing; and
using the motor and the sensed location data to controllably drive the pinion gear such that the geared nut rotates about the cylinder to cause the shock absorber to moves axially with respect to the geared nut.
14. The method of claim 13 , wherein the housing is pivotably mounted to the vehicle with a pair of oppositely disposed trunnion pins.
15. The method of claim 13 , wherein the motor is an electric motor, and further comprises a connection member for receiving and transmitting control signals to and from the motor.
16. The method of claim 13 , wherein the ground engaging assembly comprises a trailing arm assembly having a first mounting portion that pivotably connects to the piston, and a second mounting portion comprising a pivot pin spaced apart from the first mounting portion.
17. The method of claim 16 , wherein the ground engaging assembly further comprises an axle rotatably mounted in the trailing arm assembly, and a plurality of wheels mounted on the axle.
18. The method of claim 16 , further comprising a torsion link assembly connecting the piston to the cylinder such that the piston can move axially with respect to the cylinder but is prevented from moving rotationally with respect to the cylinder.
19. The method of claim 13 , wherein the shock absorbing strut comprises a portion of a landing gear for an aircraft.
20. The method of claim 13 wherein the screw thread is a trapezoidal thread.