Power device and aircraft

Abstract

The invention relates to the technical field of aircrafts, in particular to a power device and an aircraft. The power device comprises a power component, a power switching assembly, a rotor wing assembly and a wheel assembly. The power component is connected with the power switching assembly, and the power switching assembly controls one of the rotor wing assembly and the wheel assembly to be in driving connection with the power component; in the ground mode, the power switching assembly controls the wheel assembly to be in driving connection with the power component; in the flight mode, the power switching assembly controls the rotor wing assembly to be in driving connection with the power component. According to the power device provided by the invention, the rotor assemblies and the wheel assemblies share one power component, so that the complexity of the power device can be reduced, the weight and the maintenance cost are reduced, and the overall performance of the aircraft is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of aircraft, and particularly to a power device and an aircraft. Background Art

[0002] At present, most aircraft power systems are designed separately, with a power system for flight mode and a power system for ground driving mode respectively. Different motors and power transmission routes are matched according to the different rotational speed requirements of the rotor assembly and the tire assembly. This design of configuring two different power systems increases the complexity of the system, the body weight, and the cost. Summary of the Invention

[0003] The present disclosure provides a power device and an aircraft to at least solve the above technical problems existing in the prior art.

[0004] In a first aspect of the present disclosure, a power device is provided, including: a power component, a power switching component, a rotor assembly, and a wheel assembly;

[0005] The power component is connected to the power switching component, and the power switching component controls one of the rotor assembly and the wheel assembly to be drivingly connected to the power component;

[0006] In the ground mode, the power switching component controls the wheel assembly to be drivingly connected to the power component;

[0007] In the flight mode, the power switching component controls the rotor assembly to be drivingly connected to the power component.

[0008] Further, the power switching component includes an input shaft, an intermediate transmission shaft, a first output shaft, and a second output shaft;

[0009] The input shaft is connected to the power component;

[0010] The first output shaft is connected to the rotor assembly, and the second output shaft is connected to the wheel assembly;

[0011] One end of the intermediate transmission shaft is connected to the input shaft, and the other end of the intermediate transmission shaft can be selectively connected to one of the first output shaft and the second output shaft.

[0012] Further, the power switching device includes a transmission and a clutch;

[0013] The transmission includes a transmission input shaft and a transmission output shaft;

[0014] The clutch is disposed between the output shaft of the power component and the input shaft of the transmission, and the clutch is configured to selectively establish and disconnect the power connection between the output shaft of the power component and the input shaft of the transmission.

[0015] Further, the transmission input shaft includes a first transmission input shaft, a second transmission input shaft, and a transmission output shaft;

[0016] The first transmission input shaft is provided with driving gear positions, the second transmission input shaft is provided with driven gear positions, and the driving gear positions are engaged with the driven gear positions;

[0017] The rotor assembly and the wheel assembly are selectively connected to the transmission output shaft.

[0018] Further, the number of the driving gear positions is multiple, and the number of the driven gear positions is multiple;

[0019] The clutch includes a first clutch and a second clutch, the first clutch is configured to control the multiple driving gear positions, and the second clutch is configured to control the multiple driven gear positions.

[0020] Further, the power switching assembly includes a dual clutch, and the dual clutch has an input end, a first output end, and a second output end;

[0021] The first output end is connected to the rotor assembly, and the second output end is connected to the wheel assembly;

[0022] The input end selectively engages at least one of the first output end and the second output end.

[0023] Further, the wheel assembly includes a wheel shaft and two wheels disposed at both ends of the wheel shaft, the wheel shaft and the two wheels form a power group, and the wheel shaft is used for driving connection with the output shaft of the power component.

[0024] Further, the rotor assembly includes a rotating shaft and rotors disposed on the rotating shaft, and the rotating shaft is used for driving connection with the output shaft of the power component.

[0025] Further, the power component is a motor or an engine.

[0026] A second aspect of the present disclosure provides an aircraft, including the power device according to the first aspect.

[0027] The technical solutions provided by the embodiments of the present disclosure have the following advantages compared with the prior art:

[0028] The power device provided by the embodiments of the present disclosure includes a power component, a power switching component, a rotor component, and a wheel component; the power component is connected to the power switching component, and the power switching component controls one of the rotor component and the wheel component to be drivingly connected to the power component; in the ground mode, the power switching component controls the wheel component to be drivingly connected to the power component; in the flight mode, the power switching component controls the rotor component to be drivingly connected to the power component. In the embodiments of the present disclosure, the rotor component and the wheel component share a power component, which can reduce the complexity of the power device, reduce the weight and maintenance cost, and improve the overall performance of the aircraft.

[0029] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] By referring to the accompanying drawings and reading the following detailed description, the above and other objects, features, and advantages of the exemplary embodiments of the present disclosure will become easily understood. In the drawings, several embodiments of the present disclosure are shown in an exemplary rather than restrictive manner, wherein:

[0031] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0032] Figure 1 Shows the structural schematic diagram of the power device provided by the embodiments of the present disclosure Figure 1 ;

[0033] Figure 2 Shows the structural schematic diagram of the power device provided by the embodiments of the present disclosure Figure 2 ;

[0034] Figure 3 Shows the structural schematic diagram of the rotor component in the power device provided by the embodiments of the present disclosure;

[0035] Figure 4 Shows the structural schematic diagram of the wheel component in the power device provided by the embodiments of the present disclosure;

[0036] Figure 5 Shows the structural schematic diagram of the power switching component in the power device provided by the embodiments of the present disclosure Figure 1 ;

[0037] Figure 6 Shows the structural schematic diagram of the power switching component in the power device provided by the embodiments of the present disclosure Figure 2 。

[0038] Explanation of the numbers in the figure: 1, power component; 2, power switching assembly; 21, input shaft; 22, first output shaft; 23, second output shaft; 3, rotor assembly; 31, rotating shaft; 32, rotor; 4, wheel assembly; 41, wheel shaft; 42, wheel. DETAILED DESCRIPTION

[0039] In order to make the purpose, features, and advantages of the present disclosure more obvious and easy to understand, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present disclosure.

[0040] Combination Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the power device provided by the embodiment of the present disclosure includes a power component 1, a power switching assembly 2, a rotor assembly 3 and a wheel assembly 4; the power component 1 is connected to the power switching assembly 2, and the power switching assembly 2 controls one of the rotor assembly 3 and the wheel assembly 4 to be connected to the power component 1 by driving; in the ground mode, the power switching assembly 2 controls the wheel assembly 4 to be connected to the power component 1 by driving; in the flight mode, the power switching assembly 2 controls the rotor assembly 3 to be connected to the power component 1 by driving. In the embodiment of the present disclosure, the rotor assembly 3 and the wheel assembly 4 share a power component 1, which can reduce the complexity of the power device, reduce the weight and maintenance cost, and improve the overall performance of the aircraft.

[0041] Taking the case where the power component 1 is a motor and the power switching component 2 is a speed-changing clutch as an example, the motor is connected to a battery, and the motor can convert electrical energy into mechanical energy.

[0042] The aircraft is in flight mode, and the flight mode transmission ratio is used at this time, and the power transmission path is from the motor to the rotor assembly 3. The aircraft lands from the air and stops, and the speed change clutch cuts off the power transmission. The speed change clutch changes the transmission ratio to the ground mode transmission ratio. The speed change clutch switches the power transmission path from the motor to the wheel assembly 4, and the aircraft switches to the ground mode.

[0043] The aircraft is in ground mode, and the ground mode transmission ratio is used. The power transmission path is from the motor to the wheels. The aircraft stops, and the transmission clutch cuts off the power transmission. The transmission clutch changes the transmission ratio to the flight mode transmission ratio, and the transmission clutch switches the power transmission path from the motor to the rotor. The aircraft switches to flight mode.

[0044] The variable-speed clutch is a transmission with a clutch device, which can interrupt and connect power transmission, change the power output path, and change the transmission ratio. In particular, the design of its transmission ratio is matched according to the speed-torque range of the high-efficiency area of the motor and the ranges of common operating conditions of the rotor and the wheel. (For example, if the rated speed of the motor is n, the typical speed of the rotor is n1, and the typical speed of the wheel is n2, then the two transmission ratios of the transmission are: n / n1, n / n2, and this transmission ratio can be achieved by designing the radius ratio of the gears in the reducer). Similarly, the transmission can add multiple transmission ratio selections near the above two large transmission ratios, so as to allocate the optimal transmission ratio under different operating conditions of the rotor or the wheel, which is beneficial to improving efficiency and increasing the service life of the motor. In this embodiment, through the reasonable design of the transmission ratio of the variable-speed clutch, it can ensure that the motor always operates in the high-efficiency working area, improving the motor efficiency and service life. By the method of switching power transmission through the variable-speed clutch, the complexity of the aircraft power system is reduced. Through the adjustment of the transmission ratio of the variable-speed clutch, one motor can adapt to two very different operating conditions of the rotor and the wheel.

[0045] In some specific embodiments, the power switching component 2 includes an input shaft 21, an intermediate transmission shaft, a first output shaft 22, and a second output shaft 23; the input shaft 21 is connected to the power component 1; the first output shaft 22 is connected to the rotor assembly 3, and the second output shaft 23 is connected to the wheel assembly 4; one end of the intermediate transmission shaft is connected to the input shaft 21, and the other end of the intermediate transmission shaft can be selectively connected to one of the first output shaft 22 and the second output shaft 23. It can enable the rotor assembly 3 and the wheel assembly 4 to share one power component 1, which can reduce the complexity of the power device, reduce the weight and maintenance cost, and improve the overall performance of the aircraft.

[0046] Optionally, friction clutches are respectively arranged at the connection parts of the intermediate transmission shaft with the first output shaft 22 and the second output shaft 23. When it is necessary to transmit power to the first output shaft 22, the clutch between the intermediate transmission shaft and the first output shaft 22 is engaged, and the power is transmitted from the intermediate transmission shaft to the first output shaft 22 through the frictional force between the friction plates. At the same time, the clutch between the intermediate transmission shaft and the second output shaft 23 is disengaged, cutting off the power transmission to the second output shaft 23. Conversely, when it is necessary to transmit power to the second output shaft 23, the opposite clutch action is performed.

[0047] Optionally, electromagnetic clutches are installed at the connection parts of the intermediate transmission shaft with the first output shaft 22 and the second output shaft 23. By controlling the energization and de-energization of the electromagnetic coil, the suction and release of the clutch are realized, so as to control the power transmission path. For example, when the electromagnetic clutch connected to the first output shaft 22 is energized, the clutch is sucked in, and the power of the intermediate transmission shaft is transmitted to the first output shaft 22, while the electromagnetic clutch connected to the second output shaft 23 is de-energized and in a separated state, preventing the power from being transmitted to the second output shaft 23.

[0048] Optionally, a shift gear is provided at the connection part of the intermediate transmission shaft and the first output shaft 22 and the second output shaft 23. The shift gear is splined to the output shaft and can move axially on the output shaft. Corresponding meshing gears are also provided at corresponding positions on the intermediate transmission shaft. The shift gear is pushed to move on the output shaft by a shift fork mechanism. When power needs to be transmitted to the first output shaft 22, the shift fork pushes the shift gear connected to the first output shaft 22 towards the corresponding meshing gear on the intermediate transmission shaft to make them mesh, so as to transmit the power from the intermediate transmission shaft to the first output shaft 22; when it is necessary to switch to the second output shaft 23, the shift fork pushes the shift gear connected to the second output shaft 23 to mesh with another meshing gear on the intermediate transmission shaft, realizing the transmission of power to the second output shaft 23.

[0049] Optionally, the power switching assembly 2 can be a dual-clutch transmission or a planetary gear transmission. A dual-clutch transmission is a dual-output shaft transmission, and its core is to control two input shafts 21 respectively through two clutches, so as to realize the switching of power between different output shafts. A dual-clutch transmission has two input shafts 21 and two output shafts. The gears of odd gears (such as 1st, 3rd, 5th, 7th gears) are distributed on one input shaft 21, and the gears of even gears (such as 2nd, 4th, 6th gears) are distributed on the other input shaft 21. One output shaft is in transmission connection with the wheel assembly 4 to drive the wheel assembly 4, and one output shaft is in transmission connection with the rotor assembly 3 to drive the rotor assembly 3. Power switching process: One clutch (such as K1) is engaged, and the power is transmitted through the input shaft 21 of the odd gear to the corresponding output shaft; at the same time, the other clutch (such as K2) is in a disengaged state. When shifting gears is required, the K1 clutch gradually disengages, while the K2 clutch gradually engages, and the power is switched to the input shaft 21 and the output shaft of the even gear. The whole process is precisely controlled by a hydraulic system and an electronic control unit (ECU) to achieve seamless switching.

[0050] Optionally, the power switching assembly 2 can be a planetary gear transmission, and the planetary gear transmission can also realize the switching of power between different output shafts. The planetary gear transmission changes the transmission ratio by fixing different components (such as the sun gear, the ring gear or the planet carrier), so as to realize the splitting and converging of power. Power switching process: The planetary gear transmission can distribute the power to multiple output shafts and realize the switching of power through a hydraulic control mechanism.

[0051] As Figure 4 and Figure 5 shown, the input shaft 21 is connected to the power component 1; the first output shaft 22 is connected to the rotor assembly 3, and the second output shaft 23 is connected to the wheel assembly 4; the input shaft 21 can selectively drive the first output shaft 22 and the second output shaft 23.

[0052] The intermediate transmission shaft can be a component where multiple shafts and gears disposed on the shafts mesh with each other.

[0053] In some specific embodiments, the power switching device includes a transmission and a clutch; the transmission includes a transmission input shaft and a transmission output shaft; the clutch is disposed between the output shaft of the power component 1 and the transmission input shaft, and the clutch is used to selectively establish and disconnect the power connection between the output shaft of the power component 1 and the transmission input shaft.

[0054] The clutch can establish or disconnect the power connection between the output shaft of the power component 1 and the transmission input shaft as needed. When power transmission is required, the clutch engages to smoothly transmit the power of the power component 1 (such as an engine, a motor, etc.) to the transmission, enabling the aircraft or device to obtain power and operate; when power needs to be cut off, such as during gear shifting, parking, or performing certain special operations, the clutch disengages to interrupt the power transmission, preventing the power of the power component 1 from continuing to be transmitted and avoiding unnecessary movement or damage.

[0055] The transmission has different gear combinations and transmission ratios. Through gear shifting operations, the transmission can change the transmission ratio between the transmission input shaft and the transmission output shaft, so that the power device can adapt to the flight mode and the ground driving mode and can obtain appropriate rotational speed and torque outputs.

[0056] In some specific embodiments, the transmission input shaft includes a first transmission input shaft, a second transmission input shaft, and a transmission output shaft; a driving gear is disposed on the first transmission input shaft, a driven gear is disposed on the second transmission input shaft, and the driving gear meshes with the driven gear; the rotor assembly 3 and the wheel assembly 4 can be selectively connected to the transmission output shaft. The provision of the first transmission input shaft and the second transmission input shaft can provide multiple paths for power input, and according to different working scenarios and power requirements, the power can be flexibly selected to be input from different input shafts, making the power transmission more diverse and flexible to adapt to the flight mode and the ground form mode. The driving gear meshes with the driven gear, which can smoothly transmit the power from the first transmission input shaft to the second transmission input shaft, ensuring the stability and reliability of the power during transmission, reducing the impact and vibration during power transmission, and ensuring the continuity of power output.

[0057] By providing driving gears and driven gears with different numbers of teeth on the first transmission input shaft and the second transmission input shaft, different transmission ratio combinations can be formed, thereby realizing the multi-stage speed change function. This enables the rotor assembly 3 or the wheel assembly 4 to obtain appropriate rotational speed and torque under different working conditions, improving the adaptability of the entire power system to different working conditions.

[0058] The rotor assembly 3 and the wheel assembly 4 are selectively connected to the transmission output shaft, enabling the device to flexibly switch between two working modes: rotor drive and wheel drive. For example, when aerial work is required, the rotor assembly 3 is connected to the transmission output shaft, and lift is generated by the rotor to achieve flight; when traveling on the ground, the wheel assembly 4 is connected to the transmission output shaft, and ground movement is achieved through wheel drive, greatly expanding the application range and working ability of the device. Under different working modes, the power and transmission characteristics required by the device are different. By switching the connection of different components to the transmission output shaft and combining different gear combinations, the power system can better adapt to the different load requirements during rotor flight and wheel driving, ensuring stable and efficient operation of the device in various working states.

[0059] In some specific embodiments, the number of active gear wheels is multiple, and the number of driven gear wheels is multiple; the clutch includes a first clutch and a second clutch. The first clutch is used to control multiple active gear wheels, and the second clutch is used to control multiple driven gear wheels. In this embodiment, through the cooperation of multiple active gear wheels and multiple driven gear wheels, a rich combination of transmission ratios can be formed. When rapid downshifting and acceleration are required, the first clutch quickly disengages the current active gear wheel and engages the active gear wheel that can provide greater torque. At the same time, the second clutch also acts accordingly, making the driven gear wheel match the new active gear wheel, achieving rapid and smooth gear shifting and improving the power response speed.

[0060] By controlling the active and driven gear wheels respectively with two clutches, the best transmission ratio can be accurately selected according to the actual load and operating state, making the power transmission more efficient.

[0061] In some specific embodiments, the power switching component 2 includes a dual clutch, which has an input end, a first output end, and a second output end; the first output end is connected to the rotor assembly 3, and the second output end is connected to the wheel assembly 4; the input end can selectively engage at least one of the first output end and the second output end. For the dual clutch in this power switching component 2, its input end can, according to actual needs, through the engagement and disengagement operations of the clutch, select to connect with at least one of the first output end and the second output end, thereby realizing the distribution and switching of power to the rotor assembly 3 and the wheel assembly 4. For example, when aerial flight is required, the input end engages with the first output end, and power is transmitted to the rotor assembly 3 to drive the rotor to rotate and generate lift; when traveling on the ground is required, the input end engages with the second output end, and power is transmitted to the wheel assembly 4 to drive the wheels to rotate and achieve movement; or according to special requirements, the input end can engage with both the first output end and the second output end simultaneously, enabling the rotor assembly 3 and the wheel assembly 4 to obtain power at the same time.

[0062] In some specific embodiments, the wheel assembly includes a wheel axle 41 and two wheels 42 disposed at both ends of the wheel axle 41. The wheel axle 41 and the two wheels 42 form a power group, and the wheel axle 41 is used for driving connection with the output shaft of the power component 1. The wheel axle 41 can be directly connected to the output shaft of the power component 1 or connected through a transmission mechanism. When the wheel axle 41 is directly drivingly connected to the output shaft of the power component 1, the intermediate links in the power transmission process are reduced, and efficient power transmission can be achieved. After the power is output from the power component 1, it can be quickly and directly transmitted to the wheels 42, enabling the wheels 42 to obtain sufficient torque and rotational speed, and improving the acceleration performance and power response speed during ground travel.

[0063] A transmission mechanism is a component or mechanism that transmits power from one part of a machine to another part to make the machine or machine component move or operate. The traditional mechanism can include one or at least a combination of two of a gear transmission mechanism, a chain transmission mechanism, a belt transmission mechanism, a worm and worm gear transmission mechanism, and a cam mechanism.

[0064] In some specific embodiments, the rotor assembly 3 includes a rotating shaft 31 and a rotor 32 disposed on the rotating shaft 31. The rotating shaft 31 is used for driving connection with the output shaft of the power component 1. The rotating shaft 31 can be directly connected to the output shaft of the power component 1 or connected through a transmission component. When the rotating shaft 31 is directly drivingly connected to the output shaft of the power component 1, efficient power transmission can be achieved. After the power is output from the power component 1, it is directly transmitted to the rotating shaft 31, thereby driving the rotor 32 to rotate, reducing the possible energy loss caused by the intermediate transmission link, improving the power transmission efficiency, enabling the aircraft to more effectively utilize the energy of the power source, and enhancing the flight performance.

[0065] In some specific embodiments, the power component 1 is a motor or an engine.

[0066] The aircraft provided by the embodiments of the present disclosure includes the power device provided by the embodiments of the present disclosure. Since the aircraft provided by the embodiments of the present disclosure and the power device provided by the embodiments of the present disclosure have the same advantages, they will not be elaborated here.

[0067] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this embodiment can be achieved. There is no limitation herein.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present disclosure, "a plurality of" means two or more unless otherwise specifically defined.

[0069] The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily conceive of changes or substitutions, which should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A power device, characterized in that: include: A power component (1), a power switching assembly (2), a rotor assembly (3) and a wheel assembly (4); The power component (1) is connected to the power switching component (2), and the power switching component (2) controls one of the rotor component (3) and the wheel component (4) to be drivingly connected to the power component (1); In the ground mode, the power switching assembly (2) controls the wheel assembly (4) to be drivingly connected to the power component (1); In flight mode, the power switching component (2) controls the rotor component (3) to drive and connect with the power component (1).

2. The power device according to claim 1, characterized in that: The power switching assembly (2) comprises an input shaft (21), an intermediate transmission shaft, a first output shaft (22) and a second output shaft (23); The input shaft (21) is connected to the power component (1); The first output shaft (22) is connected to the rotor assembly (3), and the second output shaft (23) is connected to the wheel assembly (4); One end of the intermediate transmission shaft is connected to the input shaft, and the other end of the intermediate transmission shaft can be selectively connected to one of the first output shaft (22) and the second output shaft (23).

3. The power device according to claim 1, characterized in that: The power switching device includes a transmission and a clutch; The transmission includes a transmission input shaft and a transmission output shaft; The clutch is arranged between the output shaft of the power component (1) and the transmission input shaft, and is used to selectively establish and disconnect the power connection between the output shaft of the power component (1) and the transmission input shaft.

4. The power device according to claim 3, characterized in that: The transmission input shaft includes a transmission first input shaft, a transmission second input shaft and a transmission output shaft; The first input shaft of the transmission is provided with an active gear, the second input shaft of the transmission is provided with a driven gear, and the active gear is meshed with the driven gear; The rotor assembly (3) and the wheel assembly (4) can be selectively connected to the transmission output shaft.

5. The power device according to claim 4, characterized in that: The number of the active gear position gears is multiple, and the number of the driven gear position gears is multiple; The clutch includes a first clutch and a second clutch, the first clutch is used to control a plurality of the active gear positions, and the second clutch is used to control a plurality of the driven gear positions.

6. The power device according to claim 1, characterized in that: The power switching assembly (2) comprises a dual clutch, wherein the dual clutch has an input end, a first output end and a second output end; The first output end is connected to the rotor assembly (3), and the second output end is connected to the wheel assembly (4); The input terminal is selectively engageable with at least one of the first output terminal and the second output terminal.

7. The power device according to claim 1, characterized in that: The wheel assembly (4) comprises a wheel axle (41) and two wheels (42) arranged at both ends of the wheel axle (41); the wheel axle (41) and the two wheels (42) form a power group; the wheel axle (41) is used for driving connection with an output shaft of the power component (1).

8. The power device according to claim 1, characterized in that: The rotor assembly (3) comprises a rotating shaft (31) and a rotor (32) arranged on the rotating shaft (31); the rotating shaft (31) is used for driving connection with an output shaft of the power component (1).

9. The power device according to claim 1, characterized in that: The power component (1) is a motor or an engine.

10. An aircraft, characterized in that: A power device comprising any one of claims 1 to 9.

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