Hydraulic time sequence control system and control method for aircraft landing gear folding and unfolding

Abstract

An aircraft landing gear folding and unfolding hydraulic time sequence control system comprises a folding and unfolding actuating cylinder, an upper lock unlocking actuating cylinder, a lower lock unlocking actuating cylinder, a putting-down pressure supply pipeline and an upper folding pressure supply pipeline, one side of a piston of the folding and unfolding actuating cylinder is provided with a putting-down pressure supply cavity, and the other side of the piston is provided with a folding pressure supply cavity. The cavity wall of a pressure supply cavity of the uplock unlocking actuating cylinder is provided with two hydraulic interfaces, a first hydraulic interface close to the bottom of the pressure supply cavity is communicated with a laying-down pressure supply pipeline, and a second hydraulic interface far away from the bottom of the pressure supply cavity is communicated with a laying-down pressure supply cavity of the folding and unfolding actuating cylinder; the distance between the first hydraulic connector and the second hydraulic connector is the unlocking stroke of the uplock. The cavity wall of the pressure supply cavity of the lower lock unlocking actuating cylinder is also provided with two hydraulic interfaces, the third hydraulic interface close to the bottom of the pressure supply cavity is communicated with the upper folding pressure supply pipeline, and the fourth hydraulic interface far away from the bottom of the pressure supply cavity is communicated with the folding pressure supply cavity of the folding and unfolding actuating cylinder; the distance between the third hydraulic connector and the fourth hydraulic connector is the unlocking stroke of the down lock.

Description

Technical Field

[0001] The present invention relates to the field of aircraft design, and further relates to a hydraulic timing control system and control method for retracting and extending aircraft landing gear. Background Art

[0002] At present, most fixed-wing aircraft use retractable landing gear, the purpose of which is to reduce flight resistance, improve aircraft flight performance and fuel economy, and increase competitiveness. The mainstream retractable landing gear system adopts electrical control and hydraulic actuation. The normal retractable control system consists of a landing gear retracting and extending handle, a retracting and extending control unit, a retracting and extending selector valve, a retracting and extending actuator cylinder, an upper lock unlocking actuator cylinder, a lower lock unlocking actuator cylinder, and a hydraulic pipeline. The basic principle is that after the pilot operates the landing gear retracting and extending handle to perform the retracting and extending of the landing gear, the retracting and extending control unit receives the electrical command signal of the retracting and extending handle and outputs the control command of the retracting and extending selector valve. When the retracting and extending selector valve is in the retracted position, the hydraulic source pressure supply pipeline is connected to the retracting pressure supply pipeline to supply pressure to the lower lock unlocking actuator cylinder and the retracting and extending actuator cylinder of the front and main landing gears, and the system simultaneously executes the opening of the lower lock and the retracting of the landing gear. When the retraction and extension selection valve is connected to the lower position, the hydraulic source pressure supply pipeline is connected to the lowering pressure supply pipeline to supply pressure to the unlocking actuator cylinder and the retraction actuator cylinder of the front and main landing gear, and the system simultaneously executes opening the upper lock and lowering the landing gear. The system design of supplying pressure to the unlocking actuator cylinder and the retraction actuator cylinder at the same time will cause the upper lock or the lower lock to generate a retraction torque when the retraction actuator cylinder is unlocked, and exert an unfavorable retraction load on the upper and lower locks, reducing the service life of the upper and lower locks. In severe cases, the lock hook may be deformed and stuck and cannot be unlocked, affecting the landing safety of the aircraft. The traditional way to achieve unlocking first and then retraction is to add an actuation control valve at the front end of the retraction actuator cylinder. When the landing gear is retracted or extended, the control unit first connects the retraction selection valve to supply pressure to the upper / lower lock to unlock, and then the control unit connects the actuation control valve to supply pressure to the retraction actuator cylinder to perform the retraction and extension actuation. Since the traditional solution adds the actuation control valve hydraulic equipment, it will increase the system weight and reduce the system reliability. Summary of the invention

[0003] The purpose of the present application is to provide a hydraulic timing control system and control method for retracting and extending an aircraft landing gear, which realizes the actuation sequence of first unlocking and then retracting the landing gear through the physical connection relationship of the system hydraulic components.

[0004] A hydraulic timing control system for retracting and extending an aircraft landing gear, comprising a retracting and extending actuator cylinder, an upper lock unlocking actuator cylinder, a lower lock unlocking actuator cylinder, a lowering supply pressure pipeline and a retracting supply pressure pipeline, one side of the piston of the retracting and extending actuator cylinder is a lowering supply pressure chamber, and the other side of the piston is a retracting supply pressure chamber, characterized in that two hydraulic interfaces are provided on the wall of the supply pressure chamber of the upper lock unlocking actuator cylinder, a first hydraulic interface close to the bottom of the supply pressure chamber is connected to the lowering supply pressure pipeline, and a second hydraulic interface far from the bottom of the supply pressure chamber is connected to the lowering supply pressure chamber of the retracting and extending actuator cylinder, and the distance between the first hydraulic interface and the second hydraulic interface is the upper lock unlocking stroke; two hydraulic interfaces are also provided on the wall of the supply pressure chamber of the lower lock unlocking actuator cylinder, a third hydraulic interface close to the bottom of the supply pressure chamber is connected to the retracting supply pressure pipeline, and a fourth hydraulic interface far from the bottom of the supply pressure chamber is connected to the retracting supply pressure chamber of the retracting and extending actuator cylinder, and the distance between the third hydraulic interface and the fourth hydraulic interface is the lower lock unlocking stroke.

[0005] The aircraft landing gear retraction and extension hydraulic timing control system is characterized in that a first one-way valve is provided between the first hydraulic interface and the second hydraulic interface on the outer side of the cylinder wall of the upper lock unlocking actuator cylinder, and a second one-way valve is provided between the third hydraulic interface and the fourth hydraulic interface on the outer side of the cylinder wall of the lower lock unlocking actuator cylinder. When controlling the landing gear to be lowered, the first hydraulic interface, the second hydraulic interface and the pressure supply chamber of the upper lock unlocking actuator cylinder serve as an oil inlet passage for supplying oil from the lowering pressure supply pipeline to the lowering pressure supply chamber of the retraction actuator cylinder, and the second one-way valve serves as an oil return passage for returning oil from the stowing pressure supply chamber of the retraction actuator cylinder to the stowing pressure supply pipeline; when controlling the landing gear to be retracted, the third hydraulic interface, the fourth hydraulic interface and the pressure supply chamber of the lower lock unlocking actuator cylinder serve as an oil inlet passage for supplying oil from the stowing pressure supply pipeline to the stowing pressure supply chamber of the retraction actuator cylinder, and the first one-way valve serves as an oil return passage for returning oil from the lowering pressure supply chamber of the retraction actuator cylinder to the lowering pressure supply pipeline.

[0006] A method for controlling the hydraulic timing of the retraction and extension of an aircraft landing gear, characterized in that it comprises the following contents: 1) the above-mentioned hydraulic timing control system for the retraction and extension of an aircraft landing gear is respectively provided on the front landing gear, the left main landing gear and the right main landing gear of the aircraft; 2) the first hydraulic interfaces of the upper lock unlocking cylinders of the front landing gear, the left main landing gear and the right main landing gear are respectively connected in parallel with the lowering pressure supply pipeline, and the third hydraulic interfaces of the lower lock unlocking cylinders of the front landing gear, the left main landing gear and the right main landing gear are respectively connected in parallel with the retraction pressure supply pipeline; 3) a retraction and extension selection valve is provided on the lowering pressure supply pipeline and the retraction pressure supply pipeline, and the retraction and extension selection valve is controlled by a control unit; 4) When the aircraft needs to retract the landing gear after takeoff, the control unit controls the retraction and extension selection valve to be connected to the retraction position, the retraction supply pressure pipeline is connected to the hydraulic supply pressure pipeline for pressure release, and the lowering supply pressure pipeline is connected to the hydraulic return oil pipeline for oil return. Under the action of the hydraulic supply pressure, the piston of the lower lock unlocking actuator cylinder moves from the third hydraulic interface position to a position exceeding the fourth hydraulic interface position, completing the unlocking action. At the same time, the retraction supply pressure pipeline is connected to the oil inlet channel of the retraction supply pressure chamber of the retraction actuator cylinder, and the retraction actuator cylinder is actuated to retract the landing gear. When the landing gear is retracted, the oil in the lowering supply pressure chamber of the retraction actuator cylinder returns to the lowering supply pressure pipeline through the first one-way valve of the upper lock unlocking actuator cylinder. 5) When the aircraft approaches and the landing gear needs to be lowered, the control unit controls the retraction and extension selection valve to be connected to the lowering position, the lowering pressure supply pipeline is connected to the hydraulic pressure supply pipeline for pressure release, and the retraction pressure supply pipeline is connected to the hydraulic return pipeline for oil return. Under the action of the hydraulic supply pressure, the piston of the upper lock unlocking actuator moves from the first hydraulic interface position to a position exceeding the second hydraulic interface position, completing the unlocking action. At the same time, the lowering pressure supply pipeline is connected to the oil inlet channel of the lowering pressure supply chamber of the retraction actuator. The retraction actuator is actuated to lower the landing gear. When the landing gear is lowered, the oil in the retraction pressure supply chamber of the retraction actuator returns to the retraction pressure supply pipeline through the second one-way valve of the lower lock unlocking actuator.

[0007] The beneficial effects of the present application are as follows: 1) The present application uses the pressure supply chambers of the upper lock unlocking cylinder and the lower lock unlocking cylinder as hydraulic passages, and uses the unlocking strokes of the upper lock unlocking cylinder and the lower lock unlocking cylinder as the physical timing for controlling the movement of the retraction and extension cylinder, thereby solving the problem of adverse effects on the life and flight safety of the upper and lower locks caused by the simultaneous pressure supply of the unlocking cylinder and the retraction and extension cylinder when the landing gear is retracted and extended; 2) The method of the present patent can replace the traditional solution of adding an actuation control valve to the front end of the retraction and extension cylinder, and realize the actuation sequence control of first unlocking and then retracting when the landing gear is retracted and extended without increasing the system weight or reducing the system reliability, so as to eliminate the retraction and extension drive loads on the upper and lower locks when the landing gear is retracted and extended, thereby increasing the service life of the upper and lower locks, reducing the failure probability that the upper and lower locks may be deformed and stuck and unable to unlock, which affects the landing safety of the aircraft, and improving the safety of aircraft operation.

[0008] The present application is further described in detail below in conjunction with the accompanying drawings of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a schematic diagram of the hydraulic timing control system for retraction and extension of aircraft landing gear.

[0010] Figure 2 This is a schematic diagram of the principle of the hydraulic timing control method for retraction and extension of aircraft landing gear.

[0011] Explanation of numbers in the figure: 1-lowering pressure supply pipeline, 2-retracting pressure supply pipeline, 3-upper lock unlocking actuator, 4-retracting actuator, 5-lower lock unlocking actuator, 6-first hydraulic interface, 7-second hydraulic interface, 8-third hydraulic interface, 9-fourth hydraulic interface, 10-upper lock pressure supply chamber, 11-lowering pressure supply chamber, 12-retracting pressure supply chamber, 13-lower lock pressure supply chamber, 14-first non-return valve, 15-second non-return valve, 16-lowering pressure supply chamber oil inlet of retracting actuator, 17-retracting pressure supply chamber oil inlet of retracting actuator, 18-hydraulic pressure supply pipeline, 19-hydraulic oil return pipeline, 20-retracting selection valve, 21-front landing gear retracting actuator, 22-right main landing gear retracting actuator, 23-left main landing gear retracting actuator, 24-control unit. DETAILED DESCRIPTION

[0012] Referring to the accompanying drawings, the aircraft landing gear retraction and extension hydraulic timing control system of the present application comprises a retraction and extension actuator 4, an upper lock unlocking actuator 3, a lower lock unlocking actuator 5, a lowering pressure supply pipeline 1 and a retraction pressure supply pipeline 2. One side of the piston of the retraction and extension actuator 4 is a lowering pressure supply chamber 11, and the other side of the piston is a retraction pressure supply chamber 12. It is characterized in that two hydraulic interfaces are provided on the cavity wall of the upper lock pressure supply chamber 10 of the upper lock unlocking actuator 3, wherein the first hydraulic interface 6 close to the bottom of the pressure supply chamber is connected to the lowering pressure supply pipeline 1, and the second hydraulic interface 6 far from the bottom of the pressure supply chamber is connected to the lowering pressure supply pipeline 1. The hydraulic interface 7 is connected with the oil inlet 16 of the lowering pressure supply chamber of the retractable actuator, and the distance between the first hydraulic interface 6 and the second hydraulic interface 7 is the unlocking stroke of the upper lock; two hydraulic interfaces are also provided on the wall of the lower lock pressure supply chamber 13 of the lower lock unlocking actuator 5, and the third hydraulic interface 8 close to the bottom of the pressure supply chamber is connected with the retracting pressure supply pipeline 2, and the fourth hydraulic interface 9 far away from the bottom of the pressure supply chamber is connected with the oil inlet 17 of the retracting pressure supply chamber of the retractable actuator 4, and the distance between the third hydraulic interface 8 and the fourth hydraulic interface 9 is the unlocking stroke of the lower lock.

[0013] In the implementation, in order to solve the oil return problem, a first one-way valve 14 is provided between the first hydraulic interface 6 and the second hydraulic interface 7 on the outer side of the cylinder wall of the upper lock unlocking cylinder 3, and a second one-way valve 15 is provided between the third hydraulic interface 8 and the fourth hydraulic interface 9 on the outer side of the cylinder wall of the lower lock unlocking cylinder 5. When controlling the landing gear to be lowered, the first hydraulic interface 6, the second hydraulic interface 7 and the upper lock pressure supply chamber 10 of the upper lock unlocking cylinder 3 serve as the lowering pressure supply pipeline 1 to the retracting cylinder 4. The first one-way valve 14 serves as an oil return channel for the stowage pressure supply chamber 11 of the stowage actuator 4 to return oil to the stowage pressure supply pipeline 2; when controlling the retraction of the landing gear, the third hydraulic interface 8, the fourth hydraulic interface 9 and the lower lock pressure supply chamber 13 of the lower lock unlocking actuator 5 serve as an oil inlet channel for supplying oil to the stowage pressure supply chamber 12 of the stowage actuator 4 from the stowage pressure supply pipeline 2, and the first one-way valve 14 serves as an oil return channel for the lowering pressure supply chamber 11 of the stowage actuator 4 to return oil to the lowering pressure supply pipeline 1.

[0014] When in use, the above-mentioned aircraft landing gear retraction and extension hydraulic timing control system is respectively provided on the front landing gear retraction and extension actuating device 21, the left main landing gear retraction and extension actuating device 22 and the right main landing gear retraction and extension actuating device 23 of the aircraft; the first hydraulic interface 6 of the upper lock unlocking actuating cylinder 3 of the front landing gear, the left main landing gear and the right main landing gear retraction and extension actuating device is respectively connected in parallel with the lowering pressure supply pipeline 1, and the third hydraulic interface 8 of the lower lock unlocking actuating cylinder 5 of the front landing gear, the left main landing gear and the right main landing gear retraction and extension actuating device is respectively connected in parallel with the retraction pressure supply pipeline 2; a retraction and extension selection valve 20 is provided on the lowering pressure supply pipeline 1 and the retraction pressure supply pipeline 2, and the retraction and extension selection valve 20 is controlled by the control unit 24.

[0015] When the aircraft needs to retract the landing gear after takeoff, the control unit 24 controls the retraction selection valve 20 to be connected to the retracted position, the retraction pressure supply line 2 is connected to the hydraulic pressure supply line 18 for pressure release, and the lowering pressure supply line 2 is connected to the hydraulic return oil line 19 for oil return. Under the action of the hydraulic supply pressure, the piston of the lower lock unlocking actuator 5 moves from the position of the third hydraulic interface 8 to a position exceeding the fourth hydraulic interface 9, completing the unlocking action. At the same time, the retraction pressure supply line 2 is connected to the oil inlet channel of the retraction pressure supply chamber 12 of the retraction actuator 4, and the retraction actuator 4 is actuated to retract the landing gear. When the landing gear is retracted, the oil in the lowering pressure supply chamber 11 of the retraction actuator 4 returns to the lowering pressure supply line 1 through the first one-way valve 14 of the upper lock unlocking actuator 3.

[0016] When the aircraft needs to lower the landing gear during approach, the control unit 24 controls the lowering position of the retracting and extending selection valve 20 to be connected, the lowering pressure supply line 1 is connected to the hydraulic pressure supply line 18 for pressure release, and the retracting pressure supply line 1 is connected to the hydraulic return oil line 19 for oil return. Under the action of the hydraulic supply pressure, the piston of the upper lock unlocking actuator 3 moves from the position of the first hydraulic interface 6 to a position exceeding the second hydraulic interface 7, completing the unlocking action. At the same time, the lowering pressure supply line 1 is connected to the oil inlet channel of the lowering pressure supply chamber 11 of the retracting actuator 4, and the retracting actuator 4 is actuated to lower the landing gear. When the landing gear is lowered, the oil in the retracting pressure supply chamber 12 of the retracting actuator 4 returns to the retracting pressure supply line 2 through the second one-way valve 15 of the lower lock unlocking actuator 5.

Claims

1. A hydraulic timing control system for retracting and extending aircraft landing gear, comprising a retracting and extending actuator, an upper lock and unlocking actuator, a lower lock and unlocking actuator, a lowering pressure supply pipeline and a retracting pressure supply pipeline, one side of the piston of the retracting and extending actuator is a lowering pressure supply chamber, and the other side of the piston is a retracting pressure supply chamber, characterized in that: Two hydraulic interfaces are provided on the wall of the pressure supply chamber of the upper lock unlocking actuator cylinder, and the first hydraulic interface close to the bottom of the pressure supply chamber is connected to the lowering pressure supply pipeline, and the second hydraulic interface far from the bottom of the pressure supply chamber is connected to the lowering pressure supply chamber of the retracting actuator cylinder, and the distance between the first hydraulic interface and the second hydraulic interface is the upper lock unlocking stroke; two hydraulic interfaces are also provided on the wall of the pressure supply chamber of the lower lock unlocking actuator cylinder, and the third hydraulic interface close to the bottom of the pressure supply chamber is connected to the retracting pressure supply pipeline, and the fourth hydraulic interface far from the bottom of the pressure supply chamber is connected to the retracting pressure supply chamber of the retracting actuator cylinder, and the distance between the third hydraulic interface and the fourth hydraulic interface is the lower lock unlocking stroke.

2. The aircraft landing gear retraction and extension hydraulic timing control system according to claim 1, characterized in that: A first one-way valve is provided between the first hydraulic interface and the second hydraulic interface on the outer side of the cylinder wall of the upper lock unlocking actuator cylinder, and a second one-way valve is provided between the third hydraulic interface and the fourth hydraulic interface on the outer side of the cylinder wall of the lower lock unlocking actuator cylinder. When controlling the lowering of the landing gear, the first hydraulic interface, the second hydraulic interface and the pressure supply chamber of the upper lock unlocking actuator cylinder serve as an oil inlet passage for supplying oil from the lowering supply pressure pipeline to the lowering supply pressure chamber of the retracting actuator cylinder, and the second one-way valve serves as an oil return passage for returning oil from the retracting supply pressure chamber of the retracting actuator cylinder to the retracting supply pressure pipeline; when controlling the retraction of the landing gear, the third hydraulic interface, the fourth hydraulic interface and the pressure supply chamber of the lower lock unlocking actuator cylinder serve as an oil inlet passage for supplying oil from the retracting supply pressure pipeline to the retracting supply pressure chamber of the retracting actuator cylinder, and the first one-way valve serves as an oil return passage for returning oil from the lowering supply pressure chamber of the retracting actuator cylinder to the lowering supply pressure pipeline.

3. A hydraulic timing control method for retracting and extending aircraft landing gear, characterized in that The invention comprises the following contents: 1) the aircraft landing gear retraction and extension hydraulic timing control system as claimed in claim 1 is respectively provided on the front landing gear, the left main landing gear and the right main landing gear; 2) the first hydraulic interfaces of the upper lock unlocking cylinders of the front landing gear, the left main landing gear and the right main landing gear are respectively connected in parallel with the lowering pressure supply pipeline, and the third hydraulic interfaces of the lower lock unlocking cylinders of the front landing gear, the left main landing gear and the right main landing gear are respectively connected in parallel with the retraction pressure supply pipeline; 3) a retraction and extension selection valve is provided on the lowering pressure supply pipeline and the retraction pressure supply pipeline, and the retraction and extension selection valve is controlled by the control unit; 4) after the aircraft takes off, the retraction and extension selection valve is provided on the lowering pressure supply pipeline and the retraction pressure supply pipeline; When raising or lowering the landing gear, the control unit controls the retracting position of the retracting and extending selection valve to be connected, the retracting pressure supply pipeline is connected to the hydraulic pressure supply pipeline to pass pressure, and the lowering pressure supply pipeline is connected to the hydraulic return oil pipeline to return oil. Under the action of the hydraulic supply pressure, the piston of the lower lock unlocking actuator cylinder moves from the third hydraulic interface position to a position exceeding the fourth hydraulic interface position, completing the unlocking action, and at the same time connecting the retracting pressure supply pipeline to the oil inlet channel of the retracting pressure supply chamber of the retracting actuator cylinder, and the retracting actuator cylinder is actuated to retract the landing gear. When the landing gear is retracted, the oil in the lowering pressure supply chamber of the retracting actuator cylinder returns to the lowering pressure supply pipeline through the first one-way valve of the upper lock unlocking actuator cylinder. 5) When the aircraft approaches and the landing gear needs to be lowered, the control unit controls the retraction and extension selection valve to be connected to the lowering position, the lowering pressure supply pipeline is connected to the hydraulic pressure supply pipeline for pressure release, and the retraction pressure supply pipeline is connected to the hydraulic return pipeline for oil return. Under the action of the hydraulic supply pressure, the piston of the upper lock unlocking actuator moves from the first hydraulic interface position to a position exceeding the second hydraulic interface position, completing the unlocking action. At the same time, the lowering pressure supply pipeline is connected to the oil inlet channel of the lowering pressure supply chamber of the retraction actuator. The retraction actuator is actuated to lower the landing gear. When the landing gear is lowered, the oil in the retraction pressure supply chamber of the retraction actuator returns to the retraction pressure supply pipeline through the second one-way valve of the lower lock unlocking actuator.

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