Method of initializing a landing gear shock strut
AssigneeGoodrich Corporation
InventorsAmir M. Fazeli, Adnan Cepic, Susanne M. Reber
Life of this patent
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Abstract
A method of servicing a shock strut of a landing gear includes partially filling the shock strut with fresh oil and pressurizing the chamber with gas. The pressurizing is to a pressure level that compensates for expected gas pressure loss due to gas entrainment in the oil during operation of the shock strut. The method can be performed without weight on wheels, with weight on wheels and a constant strut stroke, or weight on wheels and a constant pressure.
Claims3
A method of servicing a shock strut of a landing gear without weight on wheels of the landing gear, the method comprising:
- partially filling a chamber of the shock strut with a predetermined amount of fresh oil;
- and
- pressurizing the chamber with gas to a level that compensates for expected gas pressure loss due to gas entrainment in the oil during operation of the shock strut, wherein the pressurizing is performed without weight on wheels of the landing gear, and the chamber is pressurized to a pressure Pgas,service of:
- P
- gas
- ,
- service
- =
- P
- gas
- ,
- nominal
-
- (
- V
- gas
-
- (
- 0
- )
- +
- V
- oil
-
- C
-
- (
- T
- )
-
- RT
- V
- gas
-
- (
- 0
- )
- )
- where Pgas,nominal is a nominal desired gas pressure with the shock strut in a fully extended position, C(T) is a coefficient based on the oil and gas used in the shock strut, Vgas(0) is a gas volume with the shock strut is in a fully extended position, R is an ideal gas coefficient, Voil is oil volume in the shock strut, and T is temperature.
A method of servicing a shock strut of a landing gear with weight on wheels of the landing gear, the method comprising:
- partially filling a chamber of the shock strut with a predetermined amount of fresh oil;
- and
- pressurizing the chamber with gas to a level that compensates for expected gas pressure loss due to gas entrainment in the oil during operation of the shock strut, wherein the pressurizing is performed with weight on wheels of the landing gear and at a constant shock strut stroke and the chamber is pressurized to a pressure Pgas,airspring(s) of:
- P
- gas
- ,
- airspring
-
- (
- s
- )
- =
- P
- gas
- ,
- nominal
-
- (
- V
- oil
- ×
- C
-
- (
- T
- )
-
- RT
- V
- gas
-
- (
- s
- )
- )
- +
- P
- gas
- ,
- airspring
-
- (
- s
- )
- ︸
- static
-
-
- airspring
-
-
- curve
- where Pgas,nominal is a nominal desired gas pressure with the shock strut in fully extended position, C(T) is a coefficient based on the oil and gas used in the shock strut, Voil is oil volume in the shock strut, R is an ideal gas constant, T is temperature, Vgas(s) is the volume of the gas at stroke s, and
- P
- gas
- ,
- airspring
-
- (
- s
- )
- ︸
- static
-
-
- airspring
-
-
- curve
- is the pressure corresponding to stroke s on a static airspring curve.
A method of servicing a shock strut of a landing gear with weight on wheels of the landing gear, the method comprising:
- partially filling a chamber of the shock strut with a predetermined amount of fresh oil;
- and
- pressurizing the chamber with gas to a level that compensates for expected gas pressure loss due to gas entrainment in the oil during operation of the shock strut, wherein the pressurizing is performed with weight on wheels and the chamber is pressurized to a pressure Pgas,service to produce a strut shock stroke S(Pgas,service) of:
- S
-
- (
- P
- gas
- ,
- service
- )
- =
- P
- gas
- ,
- nominal
- P
- gas
- ,
- service
- ×
- V
- oil
- A
- p
- ×
- C
-
- (
- T
- )
-
- RT
- +
- S
- airspring
-
- (
- P
- gas
- ,
- service
- )
- ︸
- static
-
-
- airspring
-
-
- curve
- where Pgas,nominal is a nominal desired gas pressure with the shock strut in fully extended position, Voil is oil volume in the shock strut, Ap is a shock strut piston area, C(T) is a coefficient based on the oil and gas used in the shock strut, R is an ideal gas constant, T is temperature, and
- S
- airspring
-
- (
- P
- gas
- ,
- service
- )
- ︸
- static
-
-
- airspring
-
-
- curve
- is the stroke corresponding to Pgas,service on a static airspring curve.
Dependencies are inferred from the claim text.