Landing gear for aircraft

Abstract

To motorize a landing gear of an aircraft.SOLUTION: A landing gear 1 of an aircraft includes: a leg 2 attached to a machine body 10; a linear motor 3 which is interposed between the machine body and the leg and expands and contracts along an axis X to store the leg in the machine body and deploy the leg from the machine body; and a controller 4 which controls a linear motor so that the leg is switched between a landing attitude and a storage attitude.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed herein relates to aircraft landing gear. [Background technology]

[0002] Patent Document 1 describes a landing gear for an aircraft. This conventional landing gear includes a landing gear and a hydraulic cylinder. The landing gear swings between a stored position in which it is stored in a storage compartment of the aircraft and a landing position in which it is deployed from the storage compartment. A piston rod of the hydraulic cylinder is connected to the landing gear, and the landing gear switches between the stored position and the landing position as the piston rod advances and retreats. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4240514 Summary of the Invention [Problem to be solved by the invention]

[0004] The hydraulic cylinders of the conventional landing gear are supplied with hydraulic fluid from a centralized hydraulic source in the aircraft's hydraulic system. The flow rate of hydraulic fluid supplied to raise and lower the landing gear is significantly higher than the flow rate supplied to the hydraulic control systems, e.g., the flight controls. The landing gear hydraulic cylinders impose a large burden on the weight, volume, and / or energy consumption of the aircraft's hydraulic system.

[0005] To address this issue, there are studies underway to replace the hydraulic cylinders in the landing gear with electric actuators, such as using a rotary electric motor and a gear mechanism that converts the rotary motion of the electric motor into linear motion to raise and lower the landing gear.

[0006] However, electric actuators that combine a rotary electric motor and a gear mechanism are susceptible to problems such as jamming of the gear mechanism and overload caused by such a malfunction, resulting in the electric motor burning out. To ensure that the landing gear can land even if a problem occurs, the landing gear requires a safety measure using a separate part, such as a clutch that disconnects the landing gear from the electric actuator. This makes the landing gear structure complicated, leading to increased weight and reduced reliability. As these technical issues have not been resolved, landing gears using electric actuators have not yet been put to practical use.

[0007] The technology disclosed herein provides motorized landing gear for aircraft. [Means for solving the problem]

[0008] The present disclosure relates to an aircraft landing gear. The legs attached to the aircraft, A linear motor is interposed between the fuselage and the legs, and extends and retracts along an axis to store the legs in the fuselage and deploy them from the fuselage; and a controller that controls the linear motor so that the legs are switched between a landing position and a retracted position.

[0009] The landing gear is equipped with a linear motor. The linear motor is a linear actuator that expands and contracts along an axis. The linear motor expands and contracts to switch the landing gear between a ground attitude and a stowed attitude. In the ground attitude, the landing gear is deployed from the aircraft body. In the stowed attitude, the landing gear is stored in the aircraft body.

[0010] The linear motor can be replaced with an expandable hydraulic cylinder. There is no need for a conversion mechanism, such as a gear mechanism, between the linear motor and the legs to convert the direction of motion. Therefore, there is no risk of problems in the conversion mechanism, such as the gear mechanism getting stuck. There is also no risk of problems such as the electric motor burning out.

[0011] A landing gear with a linear motor does not require safety measures using separate parts (e.g., a clutch) that were necessary for landing gear with a conventional electric actuator. The structure of a landing gear with a linear motor is not complicated, and high reliability can be ensured. In addition, since hydraulic cylinders are eliminated from the landing gear, a landing gear with a linear motor is advantageous in terms of weight reduction.

[0012] The linear motor may be connected to the leg such that the weight of the leg causes the robot to assume the landing position when the controller stops applying electricity to the linear motor.

[0013] The linear motor can freely extend and retract when the power supply from the controller is stopped. As mentioned above, there is no gear mechanism between the linear motor and the legs, so the linear motor is connected to the legs so that the weight of the legs causes the linear motor to extend and retract. When the controller stops supplying power to the linear motor, the legs will assume a landing position due to their own weight. The landing gear has a simple structure, ensuring safety in the event of a failure.

[0014] The landing gear may further include an uplock mechanism that engages with the landing gear stored in the airframe and holds the landing gear in the stored position. While the uplock mechanism locks the landing gear, the landing gear is held in the stored position even if power supply to the linear motor is stopped. This reduces energy consumption of the landing gear.

[0015] The landing gear of the aircraft further includes a sensor that outputs a measurement signal related to an attitude of the landing gear to the controller; The controller may be configured to decelerate the linear motor when the leg switching from the landing position to the storage position reaches a first predetermined position before the storage position based on the measurement signal from the sensor, and to decelerate the linear motor when the leg switching from the storage position to the landing position reaches a second predetermined position before the landing position.

[0016] In an aircraft landing gear, it is necessary to reduce the shock that occurs when the landing gear assumes a retracted position and when the landing gear assumes a landing position. In a conventional landing gear equipped with a hydraulic cylinder, a snubbing mechanism that reduces the moving speed of the piston immediately before the landing gear assumes a retracted position and immediately before the landing gear assumes a landing position is provided in the hydraulic cylinder. The snubbing mechanism has, for example, a throttle passage that restricts the flow rate of hydraulic oil in the hydraulic cylinder. Such a snubbing mechanism complicates the structure of the hydraulic cylinder and can also cause problems such as clogging of the throttle passage.

[0017] In contrast, a landing gear equipped with a linear motor can change the extension / retraction speed of the linear motor by adjusting the power supply to the linear motor using a controller. The landing gear can achieve the snubbing function even with a simple structure.

[0018] Specifically, the sensor outputs a measurement signal related to the leg posture to the controller. Since the leg posture corresponds to the stroke amount of the linear motor, the sensor may measure the stroke amount of the linear motor and output the measurement signal. The sensor may also measure the leg posture itself that changes between the retracted posture and the landing posture and output the measurement signal.

[0019] The controller can determine, based on the measurement signal from the sensor, that the leg switching from the landing position to the storage position has reached a first predetermined position before the storage position. The controller decelerates the linear motor when the leg reaches the first predetermined position. This reduces the impact when the leg reaches the storage position. The controller can also determine, based on the measurement signal from the sensor, that the leg switching from the storage position to the landing position has reached a second predetermined position before the landing position. The controller decelerates the linear motor when the leg reaches the second predetermined position. This reduces the impact when the leg reaches the landing position. Effect of the Invention

[0020] The landing gear of the above-mentioned aircraft can be electrically powered with a simple structure. [Brief description of the drawings]

[0021] [Figure 1] Figure 1 shows an aircraft landing gear. [Diagram 2] FIG. 2 is a cross-sectional view of the linear motor. [Diagram 3] FIG. 3 is a block diagram relating to the control of the landing gear. [Figure 4] Figure 4 shows the landing gear control procedure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment of an aircraft landing gear will now be described with reference to the drawings. The landing gear described here is by way of example.

[0023] FIG. 1 shows a landing gear 1 of an aircraft. The landing gear 1 constitutes the main landing gear or nose gear of the aircraft. The landing gear 1 is electrified by providing a linear motor 3, as described below. For example, if the steering mechanism of the nose gear is electrified, the electrified landing gear 1 is suitable for the nose gear of the aircraft. This is because if both the steering mechanism of the nose gear and the landing gear are electrified, there is no need to install hydraulic piping all the way to the front of the aircraft for the nose gear.

[0024] A storage compartment 11 is formed in the fuselage 10 of the aircraft. The lower part of the storage compartment 11 opens downwards. A door is attached to the opening of the storage compartment 11. The landing gear 1 is stored in the storage compartment 11 while the aircraft is flying, as shown in the upper diagram of FIG. 1. When the aircraft lands or takes off, the landing gear 1 is deployed from the storage compartment 11, as shown in the lower diagram of FIG. 1.

[0025] The landing gear 1 has a leg 2. The leg 2 has a leg pillar 21 and a wheel 22. The wheel 22 is supported at the tip of the leg pillar 21. The base end of the leg pillar 21 is supported rotatably with respect to the aircraft 10. The leg 2 swings between a landing position and a stowed position as shown by the arrow in the lower diagram of FIG. 1. The leg 2 may be provided with a steering mechanism for the wheel 22 described above.

[0026] The landing gear 1 has a linear motor 3. The linear motor 3 is a linear actuator that expands and contracts in the direction indicated by the arrow in the lower diagram of FIG. 1. FIG. 2 shows a schematic structure of the linear motor 3. The linear motor 3 has a stator 31 and a slider 32. The stator 31 is a cylinder extending along the axis X. The stator 31 has a plurality of coils 33 arranged along the axis X. The central hole 311 of the stator 31 is closed at a first end and open at a second end. The first end is an end where the stator 31 is fixed to the airframe 10, as described later, and the second end is an end opposite to the first end in the direction along the axis X.

[0027] The mover 32 is a rod extending along the axis X. The mover 32 is inserted into a central hole 311 of the stator 31 and protrudes from a second end of the stator 31. The mover 32 is capable of moving relative to the stator 31 in a direction along the axis X. Due to the relative movement of the mover 32, the linear motor 3 expands and contracts in the direction along the axis X.

[0028] The mover 32 has a plurality of permanent magnets 34 aligned along the axis X. The plurality of permanent magnets 34 are arranged so that the directions of their magnetic poles alternate. When the controller 4 shown in FIG. 3 applies an AC current to the coil 33 of the stator 31, a moving magnetic field is generated around the coil 33. The moving magnetic field attracts the permanent magnets 34 of the mover 32, generating a thrust that moves the mover 32 relative to the stator 31 in the direction along the axis X. In this way, the linear motor 3 expands and contracts.

[0029] The movable element 32 of the linear motor 3 is not limited to a circular cross-sectional shape. For example, if the cross-sectional shape of the movable element 32 is made rectangular, the space efficiency is improved compared to a movable element having a circular cross-sectional shape while maintaining the same strength. The linear motor 3 improves the layout flexibility of the landing gear 1 more than a hydraulic cylinder.

[0030] As shown in Fig. 1, a first end of the stator 31 is attached to the airframe 10. A tip of the slider 32 is attached to the landing gear 21. When the linear motor 3 retracts, the leg 2 assumes a stored position (see the upper diagram in Fig. 1), and when the linear motor 3 extends, the leg 2 assumes a landing position (see the lower diagram in Fig. 1).

[0031] When the power supply to the linear motor 3 is stopped, no magnetic field is generated, so the slider 32 of the linear motor 3 can freely move relative to the stator 31. When the weight of the legs 2 acts on the linear motor 3 when the power supply to the linear motor 3 is stopped, the linear motor 3 extends. In other words, the linear motor 3 and the legs 2 are connected to each other so that the weight of the legs 2 causes the linear motor 3 to expand and contract.

[0032] Incidentally, the stator 31 of the linear motor 3 may have both the first end and the second end open. In this case, the first end of the stator 31 is not necessarily attached to the airframe 10. Also, when the stator 31 has both the first end and the second end open, the mover 32 may protrude from both the first end and the second end of the stator 31 depending on the relative position with respect to the stator 31.

[0033] The landing gear 1 also has an uplock mechanism 12 and a downlock mechanism 13. As shown in the upper diagram of FIG. 1, the uplock mechanism 12 engages with the landing gear 2 stored in the storage chamber 11 and holds the landing gear 2 in a stored position. While the uplock mechanism 12 is locked, the landing gear 2 is held in the stored position even if power supply to the linear motor 3 is stopped. The uplock mechanism 12 promotes energy saving of the landing gear 1.

[0034] As shown in the lower diagram of Fig. 1, the down lock mechanism 13 engages with the landing gear 2 deployed from the storage room 11 and holds the landing gear 2 in the landing attitude. While the down lock mechanism 13 is locked, the landing gear 2 is held in the landing attitude even if power supply to the linear motor 3 is stopped. The down lock mechanism 13 promotes energy saving of the landing gear 1.

[0035] Both the uplock mechanism 12 and the downlock mechanism 13 are electrically driven. As shown in Fig. 3, the uplock mechanism 12 releases the lock in response to a control signal from the controller 4. Similarly, the downlock mechanism 13 releases the lock in response to a control signal from the controller 4. The uplock mechanism 12 may have a mechanism for manually releasing the lock in an emergency.

[0036] FIG. 3 shows a configuration related to the control of the landing gear 1. The landing gear 1 includes a controller 4. The controller 4 outputs a control signal (i.e., an AC signal) to the linear motor 3. The linear motor 3 expands and contracts in response to the control signal from the controller 4, and switches the leg 2 between a retracted position and a landing position. The landing gear 1 includes a sensor 5. The sensor 5 outputs a measurement signal related to the position of the leg 2 to the controller 4. The position of the leg 2 corresponds to the stroke amount of the linear motor 3. The sensor 5 may measure the stroke amount of the linear motor 3 and output the measurement signal to the controller 4. The sensor 5 may also measure the position of the leg itself, which changes between the retracted position and the landing position, and output the measurement signal to the controller 4.

[0037] Although details will be described later, the controller 4 adjusts the extension / retraction speed of the linear motor 3 upon receiving a measurement signal from the sensor 5. That is, the controller 4 decelerates the linear motor 3 immediately before the leg 2, which is switching from the landing position to the storage position, becomes the storage position. This reduces the impact when the leg 2 becomes the storage position. Also, the controller 4 decelerates the linear motor 3 immediately before the leg 2, which is switching from the storage position to the landing position, becomes the landing position. This reduces the impact when the leg 2 becomes the landing position.

[0038] The controller 4 also outputs control signals to the uplock mechanism 12 and the downlock mechanism 13 as described above.

[0039] 4 shows a procedure for controlling the raising and lowering of the leg 2 executed by the controller 4. In step S41 after starting, the controller 4 judges whether or not there is a command to raise the leg 2, that is, a command to switch the leg 2 from the landing position to the storage position. If the judgment in step S41 is No, the controller 4 judges in step S410 whether or not there is a command to lower the leg 2, that is, a command to switch the leg 2 from the storage position to the landing position. If the judgment in step S410 is No, the control process returns to step S41. The controller 4 waits for a command to raise the leg 2 or a command to lower the leg 2.

[0040] If the determination in step S41 is Yes, in step S42, the controller 4 outputs a control signal for releasing the lock to the downlock mechanism 13. Upon receiving the control signal, the downlock mechanism 13 releases the lock.

[0041] In the next step S43, the controller 4 outputs a control signal to the linear motor 3 to start retracting the linear motor 3. In step S44, the controller 4 retracts the linear motor 3 at a constant speed, and in step S45, the controller 4 determines whether the legs 2 have reached a first predetermined posture immediately before reaching the stored posture based on the measurement signal of the sensor 5. If the legs 2 have not reached the first predetermined posture, in step S44, the controller 4 continues retracting the linear motor 3 at a constant speed.

[0042] When the leg 2 has reached the first predetermined position, the controller 4 reduces the retraction speed of the linear motor 3 in step S46. In the following step S47, the uplock mechanism 12 locks the leg 2. In step S48, the controller 4 determines whether the leg lifting is complete, in other words, whether the leg 2 has reached the stored position, based on the measurement signal of the sensor 5. If the determination in step S48 is No, the controller 4 continues retracting the linear motor 3 at low speed in step S46.

[0043] If the determination in step S48 is Yes, in step S49, the controller 4 stops the power supply to the linear motor 3, thereby stopping the linear motor 3. Since the linear motor 3 is retracted at a low speed immediately before the leg 2 reaches the storage position, the impact when the leg 2 reaches the storage position is mitigated. Even if the power supply to the linear motor 3 is stopped, the leg 2 is held in the storage position because the uplock mechanism 12 locks the leg 2.

[0044] Returning to step S410, if the determination in step S410 is Yes, in step S411, the controller 4 outputs a control signal for releasing the lock to the uplock mechanism 12. Upon receiving the control signal, the uplock mechanism 12 releases the lock.

[0045] In the next step S412, the controller 4 outputs a control signal to the linear motor 3 to start extending the linear motor 3. In step S413, the controller 4 extends the linear motor 3 at a constant speed, and in step S414, the controller 4 determines whether the leg 2 has reached a second predetermined posture immediately before reaching a landing posture based on the measurement signal of the sensor 5. If the leg 2 has not reached the second predetermined posture, the controller 4 continues extending the linear motor 3 at a constant speed in step S413.

[0046] When the leg 2 has reached the second predetermined posture, the controller 4 reduces the extension speed of the linear motor 3 in step S415. In the following step S416, the down lock mechanism 13 locks the leg 2. In step S417, the controller 4 determines whether the leg lowering is completed, in other words, whether the leg 2 has reached the landing posture, based on the measurement signal of the sensor 5. If the determination in step S417 is No, the controller 4 continues extension of the linear motor 3 at low speed in step S415.

[0047] If the determination in step S417 is Yes, in step S418, the controller 4 stops the power supply to the linear motor 3, thereby stopping the linear motor 3. Since the linear motor 3 is extended at a low speed immediately before the leg 2 assumes the landing position, the impact when the leg 2 assumes the landing position is mitigated. Since the down lock mechanism 13 locks the leg 2, the leg 2 is maintained in the landing position even if the power supply to the linear motor 3 is stopped.

[0048] This landing gear 1 is equipped with a linear motor 3 as a power source for raising and lowering the landing gear 2. Since the linear motor 3 is a direct-acting actuator that expands and contracts along an axis, the linear motor 3 can replace the expanding and contracting hydraulic cylinder used in conventional landing gears.

[0049] Since the linear motor 3 is a linear actuator, a conversion mechanism for converting the direction of motion, such as a gear mechanism, is not required between the linear motor 3 and the legs 2. Therefore, in the landing gear 1, no failure in the conversion mechanism, such as jamming in the gear mechanism, occurs. Also, no failure such as seizure of the electric motor due to a malfunction of the gear mechanism occurs.

[0050] The landing gear 1 does not require safety measures such as a clutch, which is necessary in landing gear equipped with an electric actuator that combines a rotary electric motor and a gear mechanism. The landing gear 1 has a simple structure and can ensure high reliability. In addition, since the hydraulic cylinder is eliminated from the landing gear, the landing gear 1 is advantageous in terms of weight reduction.

[0051] Furthermore, the linear motor 3 extends and retracts freely when power supply from the controller 4 is stopped. As described above, there is no gear mechanism between the linear motor 3 and the legs 2, so when the controller 4 stops power supply to the linear motor 3 with the uplock mechanism 12 released, the linear motor 3 extends due to the weight of the legs 2, and the legs 2 assume a landing position. The landing gear 1 has a simple structure and can ensure safety in the event of a failure.

[0052] In addition, the linear motor 3 can easily have a large stroke amount compared to a hydraulic cylinder having the same overall length. The linear motor 3, which has a large stroke amount, increases the degree of freedom in designing the landing gear 1.

[0053] Furthermore, as described above, the landing gear 1 equipped with the linear motor 3 can change the extension / retraction speed of the linear motor 3 by the controller 4 adjusting the power supply to the linear motor 3. The landing gear 1 can achieve the snubbing function with a simple structure.

[0054] It is also possible to omit the adjustment control of the extension / retraction speed of the linear motor 3 in the landing gear 1. In this case, the landing gear 1 may omit the sensor 5, that is, the sensor that outputs a measurement signal related to the posture of the legs 2 to the controller 4. The landing gear 1 may use sensors attached to the uplock mechanism 12 and the downlock mechanism 13 instead of the sensor 5, and the controller 4 may stop the linear motor 3 when these sensors detect uplock and downlock.

[0055] The structure of the landing gear 1 shown in Fig. 1 is one example. A link mechanism may be interposed between the linear motor 3 and the leg 2. For example, in contrast to the structure in Fig. 1, a link mechanism may be provided so that the leg 2 switches from the landing position to the stowed position when the linear motor 3 extends, and the leg 2 switches from the stowed position to the landing position when the linear motor 3 retracts. [Explanation of symbols]

[0056] 1. Landing gear 10 Aircraft 2 legs 3. Linear motor 4. Controller 5 Sensors X-axis

Claims

1. The landing gear attached to the aircraft, A linear motor interposed between the aircraft body and the legs, which extends and retracts along an axis to retract the legs into the aircraft body and extend them from the aircraft body, An aircraft landing gear comprising a controller that controls the linear motor so that the landing gear switches between a landing position and a retracted position.

2. In the aircraft landing gear according to Claim 1, The landing gear of an aircraft has a landing strut that is rotatably supported relative to the airframe.

3. In the aircraft landing gear according to Claim 2, The linear motor is an aircraft landing gear, with its first end attached to the aircraft body and its second end attached to the landing gear strut.

4. In the aircraft landing gear according to any one of claims 1 to 3, The aforementioned linear motor is connected to the landing gear of an aircraft, such that when the controller stops supplying power to the linear motor, the landing gear is adjusted to assume the landing position by the weight of the landing gear.

5. In the aircraft landing gear according to Claim 4, The linear motor comprises a stator and a movable element that is movable relative to the stator in a direction along the axis, and is configured to extend and retract in a direction along the axis due to the relative movement of the movable element. There is no gear mechanism between the linear motor and the leg. An aircraft landing gear wherein, when the linear motor is de-energized, the weight of the landing gear causes the moving element to move relative to the stator, thereby causing the landing gear to assume the landing position.

6. In the aircraft landing gear according to claim 1, The system further includes a sensor that outputs a measurement signal related to the posture of the leg to the controller. The controller, based on a measurement signal from the sensor, decelerates the linear motor when the landing gear that switches from the landing position to the retracted position enters a first predetermined position before entering the retracted position, and decelerates the linear motor when the landing gear that switches from the retracted position to the landing position enters a second predetermined position before entering the landing position, for an aircraft landing gear.

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