Compact shock absorber for an aircraft undercarriage, and an undercarriage including such a shock absorber
View Patent ↗The invention relates to a shock absorber for an aircraft undercarriage, the shock absorber comprising a main cylinder in which a rod is mounted to slide telescopically, the shock absorber having one or more pneumatic chambers filled with gas, a supply of hydraulic fluid, and throttle means for throttling the hydraulic fluid such that when the shock absorber is shortened, the gas in the pneumatic chamber(s) is compressed and the hydraulic fluid is throttled, in which the pneumatic chamber(s) is/are fully contained in one or more auxiliary cylinders external to the main cylinder, and in each of which a sealed piston is slidably mounted to separate a pneumatic chamber contained in said external auxiliary cylinder from a fluid chamber in fluid flow communication with the main cylinder. According to the invention, the throttle means are disposed at the inlet of a fluid flow connection between the main cylinder and the auxiliary cylinder(s).
1. A shock absorber for an aircraft undercarriage, the shock absorber comprising a main cylinder in which a rod is mounted to slide telescopically, the shock absorber having at least one pneumatic chamber filled with gas, a supply of hydraulic fluid, and throttle means for throttling the hydraulic fluid such that when the shock absorber is shortened, the gas in the at least one pneumatic chamber is compressed and the hydraulic fluid is throttled, in which the at least one pneumatic chamber is fully contained in at least one auxiliary cylinder external to the main cylinder, and in each of which a sealed piston is slidably mounted to separate a pneumatic chamber contained in said external auxiliary cylinder from a fluid chamber in fluid flow communication with the main cylinder, wherein the throttle means are disposed at the inlet of a fluid flow connection between the main cylinder and the at least one auxiliary cylinder, and wherein the at least one auxiliary cylinder is rigidly fastened to the main cylinder and extends in a direction that is substantially perpendicular to a longitudinal axis of the shock absorber.
2. A shock absorber according to claim 1 , including controlled means for injecting hydraulic fluid into an annular chamber extending between the rod and the main cylinder, and controlled means for simultaneously exhausting the hydraulic fluid contained in the supply of fluid.
3. A shock absorber according to claim 2 , including an associated flask for receiving the hydraulic fluid coming from the supply of fluid.
4. A shock absorber according to claim 1 , including abutment means defining a retracted position of the rod in the main cylinder.
5. A shock absorber according to claim 4 , in which the abutment means can be retracted beyond a predetermined force threshold bay so as to allow the shock absorber to perform overtravel, at least in the event of a hard landing.
6. A shock absorber according to claim 1 , in which the hydraulic fluid chamber in each auxiliary cylinder is separated from the hydraulic fluid supply of the main cylinder solely by the throttle means disposed at the inlet to each said auxiliary cylinder.
7. An undercarriage including at least one shock absorber according to claim 1 .
8. A shock absorber according to claim 1 , wherein the rod carries a sealing piston inside the main cylinder, the sealing piston defining an annular chamber and an uninterrupted chamber, said annular chamber and said uninterrupted chamber being fluidly isolated from one another.
9. A shock absorber according to claim 1 , wherein said at least one pneumatic chamber is a first pneumatic chamber having a first gas pressure and a second pneumatic chamber having a second gas pressure, said second gas pressure being greater than said first gas pressure.