DEVICE FOR MONITORING THE SEALING OF A ROTORCRAFT TRANSMISSION BOX BY SUCTION

• US 20130294884A1
• Filed: 05/01/2013
• Published: 11/07/2013
• Est. Priority Date: 05/07/2012
• Status: Active Grant

• Current Assignee: Airbus Helicopters
• Original Assignee: Eurocopter
• Inventors: Huillet, Daniel, Quintric, Vincent
• Granted Patent: US 9,267,403 B2
• Time in Patent Office: Days
• US Class Current: 415/1
• CPC Class Codes: B64C 27/12 Rotor drives
• CPC Class Codes: B64D 2045/0085 Devices for aircraft health monitoring, e.g. monitoring flutter or vibration
• CPC Class Codes: F01M 1/10 Lubricating systems characterised by the provision therein of lubricant venting or purifying means, e.g. of filters
• CPC Class Codes: F01M 1/18 Indicating or safety devices concerning lubricant level F01M11/06, F01M11/12
• CPC Class Codes: F01M 11/10 Indicating devices; Other safety devices
• CPC Class Codes: F01M 11/12 concerning lubricant level
• CPC Class Codes: F16H 57/029 characterised by means for sealing the gearboxes, e.g. to improve airtightness
• CPC Class Codes: G01M 3/02 by using fluid or vacuum

Abstract

A device for monitoring the sealing state of a casing (2) of a transmission box (1) of a rotorcraft. An open airflow circuit (7) fitted with a suction generator member (10) is connected to a vent (5) of the casing (2). Regulator means (12) maintain stable suction in the airflow circuit (7) relative to a setpoint threshold (S), the regulator means being controlled in response to a pressure gauge (13) for measuring the suction generated inside the airflow circuit (7). The device is used on the ground to detect a source of leakage in the casing (2) and in flight to retain lubricant inside the casing (2) in the event of there being a source of leakage.

Claims

1. A device for monitoring the sealing state of a casing housing lubricated moving members of a transmission box of a rotorcraft, wherein the device comprises:

an airflow circuit open to the atmosphere at its downstream end, the airflow circuit having coupling means at its upstream end for coupling in leaktight manner to a vent of the casing, and being fitted with a suction generator member for generating suction inside the airflow circuit, operation of the suction generator member being under the control of control means; and

regulator means for regulating said suction that is maintained stable inside the airflow circuit relative to a setpoint threshold (S), operation of the regulator means being controlled at least to depend on a pressure gauge for measuring the suction generated inside the airflow circuit.

2. A device according to claim 1, wherein the device includes information generator means for generating information at least about the operation of the suction generator member by the regulator means.

3. A device according to claim 2, wherein the information generator means comprise time-measuring means associated at least with detector means for detecting both activation of the suction generator member and conversely stopping thereof, which time-measuring means are possibly also associated with evaluator means for evaluating the electrical energy consumed by the suction generator member.

4. A device according to claim 2, wherein the information generator means are associated at least with memory means for storing the information that is generated, and possibly also with transcription means for transcribing that information.

5. A device according to claim 1, wherein the control means includes a switch for manually controlling the selective supply of electrical power to the suction generator member.

6. A device according to claim 1, wherein the regulator means comprise calculation means for calculating the setpoint threshold (S) relative to a predetermined setpoint pressure difference (DP) between the suction generated inside the airflow circuit and atmospheric pressure as measured by a pressure sensor placed outside the airflow circuit.

7. A device according to claim 6, wherein the regulator means include a valve arranged on an inlet for outside air placed as a branch circuit between the ends of the airflow circuit, the valve being operable by an actuator that is operated under control of the calculation means.

8. A device according to claim 7, wherein the information generator means generate additional information relating at least to the measured atmospheric pressure, and possibly also to the operation of the valve by the actuator.

9. A device according to claim 2, wherein the device includes alarm means under the control of the information generator means.

10. A device according to claim 1, wherein the device includes at least one bowl at the downstream end of the airflow circuit for recovering lubricant potentially conveyed along the airflow circuit, and possibly also a particle filter placed upstream from the bowl.

11. A device according to claim 6, wherein during a stage of the transmission box operating in flight, the device is a device for retaining lubricant inside the casing by preventing it from escaping through a leakage source.

12. A rotorcraft transmission box of the gearbox type for providing mechanical transmission of motion between at least two members, the box being fitted with a device according to claim 1.

13. A rotorcraft transmission box of the bearing box type for mounting at least one rotary shaft, the box being fitted with a device according to claim 1.

14. A method of using a device according to claim 1, wherein prior to putting a transmission box into service, wherein the method comprises the following operations:

connecting the airflow circuit to the casing via the vent with which the casing is provided;

generating suction inside the casing by operating the suction generator member under the control of the regulator means, and using the regulator means to maintain the suction inside the casing relative to said setpoint threshold (S);

an operator monitoring the operation of the suction generator means by the regulator means, at least concerning the frequency with which it is put into operation compared with a setpoint frequency based on there being no significant passage for outside air through the casing via a lubricant leakage source; and

in the event of a said leakage source being detected on the basis of said monitoring operation, the operator visually observing the casing while suction is maintained therein and identifying the location of at least one cause of leakage.

15. A method according to claim 14, wherein the monitoring operation is an operation of consulting data delivered by the information generator means.

16. A method of using a device according to claim 2, wherein the method comprises the following operations:

A) during a stage in which a said transmission box is in operation, the device being installed on board a rotorcraft and being connected to the casing;

generating suction inside the casing by operating the suction generator member under the control of the regulator means until reaching said setpoint threshold (S), and using the regulator means to maintain the suction inside the casing stable relative to said setpoint threshold (S); and

collecting and storing a history of the data generated by the information generator means;

then

B) during a stage of maintaining the rotorcraft on the ground;

playing back the history in transcribed form in order to enable an operator to detect a potential source of leakage by observing the data history; and

then

in the event of a said leakage source being detected;

generating suction inside the casing by operating the suction generator member under the control of the regulator means and using the regulator means to maintain the suction inside the casing stable relative to said setpoint threshold (S); and

an operator visually observing the casing while suction is being maintained therein and identifying the location of at least one cause of leakage.

17. A method according to claim 16, wherein during a stage of the transmission box operating on board the rotorcraft, wherein the method includes the following additional operations:

measuring atmospheric pressure by means of the sensor and measuring the suction maintained inside the casing by means of the pressure gauge;

calculation means evaluating the current pressure difference between the measured atmospheric pressure and the suction inside the casing, and comparing the current pressure difference with the setpoint pressure difference (DP); and

said calculation means determining the setpoint threshold (S) to be maintained in order to maintain the setpoint pressure difference (DP).

18. A method according to claim 17, wherein the method comprises the following additional operations:

on the basis of said comparison operation, the calculation means discovering a current pressure difference value that is greater than the setpoint pressure difference value (DP); and

activating the actuator to open the valve so as to cause outside air to enter into the inside of the airflow circuit until reaching the setpoint pressure difference value (DP) inside the airflow circuit.