초록 ▼

The invention relates to a telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis between a retracted position and an extended position. The actuator includes an auxiliary rod mounted to slide telescopically in the main rod along said sl

The invention relates to a telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis between a retracted position and an extended position. The actuator includes an auxiliary rod mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, the actuator including controlled retaining means for retaining the auxiliary rod in the retracted position inside the main rod.

대표청구항 ▼

What is claimed is: 1. A telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis X between a retraced position and an extended position, the telescopic actuator including an auxiliary rod mounted to slide telescopically in the main rod a

What is claimed is: 1. A telescopic actuator comprising a cylinder in which a main rod is mounted to slide telescopically along a sliding axis X between a retraced position and an extended position, the telescopic actuator including an auxiliary rod mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, the actuator including controlled retaining means carried by the main rod and by the auxiliary rod for retaining the auxiliary rod in the retracted position inside the main rod, and wherein said retaining means are carried by the main rod and by the auxiliary rod, and comprises controlled sliding means for controlling sliding of the main rod in the cylinder, said controlled sliding means comprising: a motor member; a lead screw extending along the sliding axis and rotatably mounted on the cylinder so as to be driven in rotation by the motor member; a nut secured to the main rod and co-operating with the lead screw; and antirotation means for preventing the main rod from rotating relative to the cylinder, and in which the lead screw has one end guided by a first ball joint mounted on the cylinder, and another end guided by a second ball joint slidably mounted in the auxiliary rod. 2. An actuator according to claim 1, in which the controlled retaining means comprises: a catch carried by the main rod; a step carried by the auxiliary rod to co-operate with the catch; and a lockable sleeve carried by the main rod and displaceable axially between a release position in which the sleeve leaves the catch free to deform radially under the effect of a step of the auxiliary rod going past it, and a locking position in which the sleeve prevents the catch from deforming radially, the catch then co-operating with the step to define the retracted position of the auxiliary rod. 3. An actuator according to claim 1, in which the controlled retaining means comprise a resilient member adapted to hold the auxiliary rod pressed against a retractable axial abutment of said controlled retaining means defining the retracted position of the auxiliary rod, while allowing the auxiliary rod to retract a little into the main rod beyond its retracted position. 4. An actuator according to claim 1, in which the lead screw is prevented from moving axially relative to the cylinder by a double-acting axial abutment. 5. An actuator according to claim 1, including a sensor for sensing displacement of the auxiliary rod relative to the cylinder. 6. A method of using an actuator according to claim 1, the method comprising the step of causing the actuator to operate: either in a normal mode in which the retaining means are controlled to retain the auxiliary rod in the retracted position inside the main rod; or else, at least under circumstances in which the main rod is jammed in the cylinder, in an emergency mode in which the retaining means are controlled to cease retaining the auxiliary rod in the retracted position. 7. An actuator according to claim 1, including sliding brake means for braking the sliding of the auxiliary rod in the main rod in the extension direction. 8. An actuator according to claim 7, in which the brake means comprise: a driver co-operating with the main rod via a reversible helical connection having the sliding axis as its axis so that the driver rotates when the auxiliary rod slides in the main rod; a bushing mounted to rotate on the auxiliary rod about the sliding axis on being driven in rotation by the driver, at least while the auxiliary rod is extending from the main rod, the bushing carrying permanent magnets; and a winding mounted stationary on the auxiliary rod with which the permanent magnets carried by the bushing interact electromagnetically while the bushing is being driven in rotation by the driver. 9. An actuator according to claim 7, in which the brake means comprise: a driver co-operating with the main rod via a reversible helical connection having the sliding axis as its axis so that the driver rotates when the auxiliary rod slides in the main rod; a bushing mounted to rotate on the auxiliary rod about the sliding axis on being driven in rotation by the driver, at least while the auxiliary rod is extending from the main rod, a jaw being mounted to move axially on the bushing; and an electromagnet mounted stationary on the auxiliary rod to attract the jaw selectively so that the jaw rubs against a friction member mounted stationary on the auxiliary rod when the bushing is driven in rotation by the driver. 10. An actuator according to claim 7, in which the brake means comprise: a driver co-operating with the main rod via a reversible helical connection having the sliding axis as its axis so that the driver rotates when the auxiliary rod slides in the main rod; a bushing mounted to rotate on the auxiliary rod about the sliding axis on being driven in rotation by the driver, at least while the auxiliary rod is extending from the main rod; and a friction member mounted on the auxiliary rod and against which the bushing rubs while it is being driven in rotation by the driver. 11. An actuator according to claim 10, in which the brake means further comprise rotary speed-increasing gearing disposed between the driver and the bushing so that the bushing rotates faster than the driver. 12. An actuator according to claim 10, in which the driver forms a bearing for the auxiliary rod in the main rod. 13. A telescopic actuator comprising: a cylinder in which a main rod is mounted to slide telescopically along a sliding axis X between a retraced position and an extended position, an auxiliary rod mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, controlled retaining means carried by the main rod and by the auxiliary rod for retaining the auxiliary rod in the retracted position inside the main rod, wherein said retaining means are carried by the main rod and by the auxiliary rod, and the controlled retaining means comprise: a catch carried by the main rod; a step carried by the auxiliary rod to co-operate with the catch; and a lockable sleeve carried by the main rod and displaceable axially between a release position in which the sleeve leaves the catch free to deform radially under the effect of a step of the auxiliary rod going past it, and a locking position in which the sleeve prevents the catch from deforming radially, the catch then co-operating with the step to define the retracted position of the auxiliary rod. 14. A telescopic actuator comprising: a cylinder in which a main rod is mounted to slide telescopically along a sliding axis X between a retraced position and an extended position, an auxiliary rod mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, controlled retaining means carried by the main rod and by the auxiliary rod for retaining the auxiliary rod in the retracted position inside the main rod, wherein said retaining means are carried by the main rod and by the auxiliary rod, and sliding brake means for braking the sliding of the auxiliary rod in the main rod in the extension direction, the sliding brake means comprising: a driver co-operating with the main rod via a reversible helical connection having the sliding axis as its axis so that the driver rotates when the auxiliary rod slides in the main rod; a bushing mounted to rotate on the auxiliary rod about the sliding axis on being driven in rotation by the driver, at least while the auxiliary rod is extending from the main rod; and a friction member mounted on the auxiliary rod and against which the bushing rubs while it is being driven in rotation by the driver. 15. An actuator according to claim 14, in which the brake means comprise: a driver co-operating with the main rod via a reversible helical connection having the sliding axis as its axis so that the driver rotates when the auxiliary rod slides in the main rod; a bushing mounted to rotate on the auxiliary rod about the sliding axis on being driven in rotation by the driver, at least while the auxiliary rod is extending from the main rod, a jaw being mounted to move axially on the bushing; and an electromagnet mounted stationary on the auxiliary rod to attract the jaw selectively so that the jaw rubs against a friction member mounted stationary on the auxiliary rod when the bushing is driven in rotation by the driver. 16. An actuator according to claim 14, in which the brake means further comprise rotary speed-increasing gearing disposed between the driver and the bushing so that the bushing rotates faster than the driver. 17. An actuator according to claim 14, in which the driver forms a bearing for the auxiliary rod in the main rod.