Active and passive differential control hydraulic control loop and helicopter undercarriage

Abstract

The invention discloses an active and passive differential control hydraulic control loop and a helicopter undercarriage, and belongs to the field of mechanical design. In order to solve the problems that a traditional undercarriage is insufficient in terrain adaptive capacity, a parking apron needs to be built on a complex terrain in advance, and the terrain adaptive capacity of a helicopter cannot be improved. The landing leg units are provided with hydraulic control loops, so that various control modes of the landing gear can be realized, such as active control of the landing leg units, passive differential control among the landing leg units and active differential control between the front and rear groups of landing leg units; through active differential control between the two landing leg units in the group, the helicopter can change the structural postures of the landing leg units according to topographic conditions, and it is guaranteed that the helicopter body can be kept horizontal and stable when the helicopter lands on the bumpy or inclined ground. The helicopter landing device is mainly used for landing of helicopters in complex terrains.

Description

Technical Field

[0001] The invention belongs to the field of mechanical design, and in particular relates to a hydraulic control circuit of active and passive differential control and a helicopter landing gear. Background Art

[0002] As a vertical take-off and landing aircraft, helicopters are often used for tasks in complex terrain environments, such as mountain rescue, terrain survey, etc. However, the traditional helicopter landing gear structure is relatively fixed, such as skid type, front three-point type and rear three-point type, etc. These traditional landing gears have insufficient terrain adaptability and require the construction of a helipad on complex terrain in advance, which cannot improve the helicopter's terrain adaptability. Summary of the invention

[0003] In view of this, the present invention provides a hydraulic control circuit with active and passive differential control and a helicopter landing gear, which can select active control mode, passive differential control mode or active differential control mode for landing according to the usage scenario, so as to increase the terrain adaptability and stability of the helicopter during landing.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A hydraulic control circuit for active and passive differential control, comprising a hydraulic control unit, wherein N hydraulic control units are provided, N ≥ 3, each hydraulic control unit corresponds to a landing leg unit, and is configured with the landing leg unit as a landing leg control mechanism, the N landing leg control mechanisms are divided into M groups and arranged side by side, M ≥ 2, and each landing leg unit is provided with a first actuator;

[0006] Each hydraulic control unit includes a first liquid inlet pipe, a first liquid outlet pipe, an active control oil circuit, a passive control oil circuit, a first electro-hydraulic servo valve and an electromagnetic reversing valve for switching the active control oil circuit and the passive control oil circuit. One end of the first liquid inlet pipe is connected to the rod chamber of the first actuator cylinder, and the other end is connected to the electromagnetic reversing valve. One end of the first liquid outlet pipe is connected to the rodless chamber of the first actuator cylinder, and the other end is connected to the first liquid outlet pipes in the remaining hydraulic control units. The first liquid inlet pipe and the first liquid outlet pipe are both connected to the first electro-hydraulic servo valve. The first electro-hydraulic servo valve can switch the rodless chamber of the first actuator cylinder. The passive control oil circuit is connected to the electromagnetic reversing valve at one end and the passive control oil circuit in the other hydraulic control units at the other end; when the electromagnetic reversing valve controls the passive control oil circuit to be connected to the first liquid inlet pipe, each first actuator cylinder is connected to form a closed loop via the first liquid inlet pipe, the passive control oil circuit and the first liquid outlet pipe to realize the passive differential control between each first actuator cylinder; the active control oil circuit is designed to be connected in parallel with the passive control oil circuit, and the active control oil circuit is connected to the first liquid inlet pipe via the electromagnetic reversing valve;

[0007] A second differential oil pump is provided between two adjacent groups of landing leg control mechanisms. The second differential oil pump is respectively connected to the active control oil circuits in the two adjacent groups of landing leg control mechanisms, so that when the electromagnetic reversing valves in the two adjacent groups control the active control oil circuit to be connected to the first liquid inlet pipe, the first actuator cylinders in the front and rear groups can be connected to form a closed loop via the first liquid inlet pipe, the first liquid outlet pipe and the active control oil circuit, and the second differential oil pump is started to realize active differential control between the front and rear groups of landing leg control mechanisms.

[0008] In addition, the present invention also proposes an active and passive differentially controlled helicopter landing gear that uses the above hydraulic control circuit to connect each landing leg unit. The landing gear includes a landing gear body, a landing leg unit and a hydraulic control circuit. The landing leg unit is installed on the landing gear body. The landing leg unit can adopt a single degree of freedom structure or a two-degree of freedom structure to increase the adaptability of the leg to the ground.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. The landing leg unit of the present invention is equipped with a hydraulic control circuit to realize multiple control modes of the landing gear, such as active control of the landing leg unit, passive differential control between each landing leg unit, and active differential control between the front and rear landing leg units. When there are two landing leg units in each group, the active differential control between the two landing leg units in the group enables the helicopter to change the structural posture of the landing leg unit according to the terrain conditions, ensuring that the helicopter can maintain a horizontal and stable body when landing on a rugged or inclined ground.

[0011] 2. In the active control mode, the oil tank actively supplies oil to make each actuator move and realize precise control. In the passive differential control mode, the oil tank does not supply oil, and the coordinated differential between the landing legs is realized by relying on the passive flow of oil between the actuators, which saves energy and has a simple structure. In the active differential control mode, the oil tank does not supply oil, and the active differential control between the landing legs is realized by relying on the active flow of oil between the actuators, which can flexibly adjust the posture of each leg to adapt to complex terrain.

[0012] 3. The hydraulic control circuit of the present invention is compatible with different degrees of freedom and different numbers of landing gear legs, and has good flexibility and expandability. This makes it easier to adjust and optimize the landing gear system when facing different mission requirements and usage scenarios, without the need for large-scale redesign of the hydraulic control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are incorporated as part of this application and are used to provide a further understanding of the present invention.

[0014] Figure 1It is a structural schematic diagram when the landing leg unit adopts a single degree of freedom structure, a is the first configuration of the single degree of freedom landing leg unit, and b is the second configuration of the single degree of freedom landing leg unit.

[0015] Figure 2 It is a structural schematic diagram when the landing leg unit adopts a two-degree-of-freedom structure, a is the first configuration of the two-degree-of-freedom landing leg unit, b is the second configuration of the two-degree-of-freedom landing leg unit, and c is the third configuration of the two-degree-of-freedom landing leg unit.

[0016] Figure 3 This is a schematic diagram of the hydraulic control of the landing gear of Example 7.

[0017] Figure 4 This is a schematic diagram of the hydraulic control of the landing gear of Example 8.

[0018] Figure 5 This is a schematic diagram of hydraulic control of the landing gear in Example 8 using active control mode.

[0019] Figure 6 This is a schematic diagram of hydraulic control of the landing gear in Example 8 using a passive differential control mode.

[0020] Figure 7 This is a schematic diagram of hydraulic control of the landing gear in Example 8 using the left and right active differential control mode.

[0021] Figure 8 This is a schematic diagram of hydraulic control of the landing gear in Example 8 using the front and rear active differential control mode.

[0022] Fig. 9 This is a schematic diagram of the hydraulic control of the landing gear of Example 1.

[0023] Fig.10 This is a schematic diagram of the hydraulic control of the landing gear of Example 2.

[0024] Fig.11 This is a schematic diagram of hydraulic control of the landing gear in Example 2 using an active control mode.

[0025] Fig.12 This is a schematic diagram of hydraulic control of the landing gear in Example 2 using a passive differential control mode.

[0026] Fig.13 This is a schematic diagram of hydraulic control of the landing gear in Example 2 using the left and right active differential control mode.

[0027] Fig.14 This is a schematic diagram of hydraulic control of the landing gear in Example 2 using the front and rear active differential control mode.

[0028] Fig.15This is a schematic diagram of the hydraulic control of the landing gear of Example 3.

[0029] Fig.16 This is a schematic diagram of the hydraulic control of the landing gear of Example 4.

[0030] Fig.17 This is a schematic diagram of hydraulic control of the landing gear in Example 4 using an active control mode.

[0031] Fig.18 Schematic diagram of hydraulic control of the landing gear in Example 4 using a passive differential control mode.

[0032] Fig.19 This is a schematic diagram of hydraulic control of the landing gear in Example 4 using the left and right active differential control mode.

[0033] Fig. 20 It is a schematic diagram of hydraulic control of the front and rear three landing leg control mechanisms in the landing gear in Example 4 using an active differential control mode.

[0034] Fig.21 It is a schematic diagram of hydraulic control of two adjacent groups of landing leg control mechanisms in the landing gear in Example 4 adopting a front-rear active differential control mode.

[0035] Fig. 22 This is a schematic diagram of the hydraulic control of the landing gear of Example 5.

[0036] Fig.23 This is a schematic diagram of the hydraulic control of the landing gear of Example 6.

[0037] Fig.24 This is a schematic diagram of hydraulic control of the landing gear in Example 6 using an active control mode.

[0038] Fig.25 This is a schematic diagram of hydraulic control of the landing gear in Example 6 using a passive differential control mode.

[0039] Fig.26 This is a schematic diagram of hydraulic control of the left front leg and the right rear leg of the landing gear in Example 6 using an active differential control mode.

[0040] Fig. 27 This is a schematic diagram of hydraulic control of the left rear leg and the right front leg of the landing gear in Example 6 using an active differential control mode.

[0041] Explanation of the reference numerals: 1-first actuator; 2-first connecting rod; 3-support rod; 4-first landing leg; 5-second actuator; 6-second connecting rod; 7-third connecting rod; 8-second landing leg; 9-fourth connecting rod; 10-fifth connecting rod; 11-third landing leg; 12-oil tank; 13-main oil circuit; 14-first branch oil circuit; 15-second branch oil circuit; 16-oil closing valve; 17-liquid level gauge; 18-air filter; 19-one-way hydraulic pump; 20-hydraulic oil filter; 21-one-way valve ; 22-accumulator; 23-pressure gauge; 24-second differential oil pump; 25-first differential oil pump; 26-first series oil circuit; 27-parallel oil circuit; 28-second series oil circuit; 29-first liquid inlet pipe; 30-first liquid outlet pipe; 31-active control oil circuit; 32-passive control oil circuit; 33-first electro-hydraulic servo valve; 34-electromagnetic reversing valve; 35-second liquid inlet pipe; 36-second liquid outlet pipe; 37-second electro-hydraulic servo valve; 38-overflow valve; 39-oil return valve; 40-switch valve. DETAILED DESCRIPTION

[0042] The invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] like Figures 1 to 27 As shown, this embodiment provides a helicopter landing gear with active and passive differential control, including a landing leg unit and a hydraulic control circuit. Figure 1 and Figure 2 As shown, there are N landing leg units, each of which can adopt a single-degree-of-freedom structure or a two-degree-of-freedom structure. The landing gear can use a corresponding landing leg configuration according to actual needs.

[0044] like Figure 1 As shown, when the landing leg unit adopts a single degree of freedom structure, an actuator is designed, combined with Figure 1 a. The cylinder of the first actuator 1 is connected to the landing gear body, and the piston rod of the first actuator 1 faces the ground. The first actuator 1 is used as a landing leg. When the helicopter lands, the piston rod of the first actuator 1 extends and contacts the ground to achieve the landing purpose of the helicopter. Figure 1b. The actuator can also be used in conjunction with a connecting rod to drive the landing leg to swing. The landing leg unit also includes a first connecting rod 2, a support rod 3 and a first landing leg 4. The first landing leg 4 is a bending rod. One end of the first connecting rod 2 is hinged to the landing gear body, and the other end is movably connected to the top of the first landing leg 4. One end of the support rod 3 is hinged to the landing gear body, and the other end is hinged to the bending part of the first landing leg 4. The cylinder body of the first actuator 1 is hinged to the landing gear body, and the piston rod end of the first actuator 1 is hinged to the connection between the first connecting rod 2 and the first landing leg 4 to drive the first landing leg 4 to swing. The configuration of this landing leg unit utilizes the lever principle. When the piston rod of the first actuator cylinder 1 retracts, the piston rod of the first actuator cylinder 1 pulls the first landing leg 4 to swing outward around the other end of the support rod 3. When the piston rod of the first actuator cylinder 1 extends, the piston rod of the first actuator cylinder 1 pushes the first landing leg 4 to swing inward around the other end of the support rod 3. In other words, the posture of the landing leg can be adjusted by extending and retracting the piston rod of the first actuator cylinder 1.

[0045] like Figure 2 As shown, when the landing leg unit adopts a two-degree-of-freedom structure, two actuators are designed. Figure 2 a. The two actuators are connected in series. The second actuator 5 is used as a side swing leg, and the first actuator 1 is used as a lifting leg. The first actuator 1 and the second actuator 5 are connected in series as a whole to form a landing leg. Specifically, the cylinder body of the second actuator 5 is connected to the landing gear body, and the end of the piston rod of the second actuator 5 is connected to the cylinder body of the first actuator 1. When the helicopter lands, the second actuator 5 can drive the first actuator 1 to swing sideways to increase the flexibility of the legs. The extension and retraction of the piston rod in the first actuator 1 can achieve the extension or retraction of the legs to adapt to landing on complex terrain. Figure 2 b and Figure 2 c. The two actuators can also be used in conjunction with the connecting rod to form a variety of configurations to increase the number of leg movement postures. Figure 2 b. The landing leg unit also includes a second connecting rod 6, a third connecting rod 7 and a second landing leg 8. One end of the second connecting rod 6 is hinged to the landing gear body, and the other end is hinged to the middle position of the second landing leg 8. The cylinder body of the first actuator 1 is hinged to the landing gear body via the third connecting rod 7. The end of the piston rod of the first actuator 1 is hinged to the middle position of the second connecting rod 6. The cylinder body of the second actuator 5 is hinged to the third connecting rod 7, and the end of the piston rod of the second actuator 5 is hinged to the top of the second landing leg 8. When the piston rod of the first actuator 1 is stationary and the piston rod of the second actuator 5 is extended, the second actuator 5 can drive the second landing leg 8 to swing inward. When the piston rods of the first actuator 1 and the second actuator 5 are retracted, the second landing leg 8 can swing outward. Figure 2c. The landing leg unit further comprises a fourth connecting rod 9, a fifth connecting rod 10 and a third landing leg 11. One end of the fourth connecting rod 9 is hinged to the landing gear body, and the other end is hinged to the top end of the third landing leg 11. The cylinder body of the first actuator 1 is hinged to the landing gear body, the end of the piston rod of the first actuator 1 is hinged to the fourth connecting rod 9, the cylinder body of the second actuator 5 is hinged to the fourth connecting rod 9, the end of the piston rod of the second actuator 5 is hinged to one end of the fifth connecting rod 10, and the other end of the fifth connecting rod 10 is fixed to the third landing leg 11. When the piston rod of the first actuator 1 is extended and the piston rod of the second actuator 5 is retracted, the third landing leg 11 swings inwardly, and when the piston rod of the second actuator 5 is extended and the piston rod of the first actuator 1 is retracted, the third landing leg 11 swings outwardly. It can be seen that, in this embodiment, through the combined action of the first actuator 1 and the second actuator 5, the landing legs can be driven to swing inward or outward, thereby increasing the posture of the legs and improving the adaptability to complex terrain environments.

[0046] like Figures 3 to 27 As shown, the hydraulic control circuit of this embodiment includes an oil tank 12, a main oil circuit 13, a first branch oil circuit 14, a second branch oil circuit 15 and an oil closing valve 16. One end of the main oil circuit 13 is connected to the oil tank 12, and the other end is connected to the first branch oil circuit 14 and the second branch oil circuit 15 respectively. The first branch oil circuit 14 is connected to the first actuator 1. The oil tank 12 can supply oil to the first actuator 1 through the main oil circuit 13 and the first branch oil circuit 14. The oil closing valve 16 is arranged on the first branch oil circuit 14 to control whether the oil tank 12 supplies oil to the first actuator 1. The second branch oil circuit 15 is connected to the second actuator 5. The oil tank 12 can supply oil to the second actuator 5 through the main oil circuit 13 and the second branch oil circuit 15. The oil tank 12 is provided with a level gauge 17 for monitoring whether the oil volume in the oil tank 12 is maintained within a safe and usable range. An air filter 18 is also installed at the oil filling port of the oil tank 12 to ensure that the outside air is clean and free of impurities when entering the oil tank 12 to ensure the oil quality. A one-way hydraulic pump 19, a hydraulic oil filter 20 and a one-way valve 21 are sequentially arranged on the main oil circuit 13 and along the flow direction of the hydraulic oil. The one-way valve 21 can prevent the hydraulic oil from flowing back to the one-way hydraulic pump 19. The hydraulic oil filter 20 is used to filter impurities in the hydraulic oil pumped out. An accumulator 22 and a pressure gauge 23 are also arranged at the output end of the one-way hydraulic pump 19. The accumulator 22 is mainly used to reduce the pressure fluctuation of the hydraulic system. The pressure gauge 23 is used to monitor the output oil pressure of the one-way hydraulic pump 19 in real time.

[0047] The hydraulic control circuit of this embodiment also includes a hydraulic control unit, and the hydraulic control unit is provided with N hydraulic control units, each hydraulic control unit corresponds to a landing leg unit, and forms a landing leg control mechanism with the landing leg unit, and the N landing leg control mechanisms are divided into M groups, M≥2, and the M groups of landing leg control mechanisms are arranged side by side and installed at the bottom of the helicopter. Specifically, N can be an odd number or an even number. When N=3, the three landing leg control mechanisms are divided into two groups, one of which is a group, and the landing leg control mechanism is set as a single-leg mechanism group, and the other two landing leg control mechanisms are set as a group and arranged side by side left and right, and the landing leg control mechanism is set as a double-leg mechanism group. The two groups of landing leg control mechanisms are installed side by side at the bottom of the helicopter, and the double-leg mechanism group is in front and the single-leg mechanism group is in the back. When N=4, the four landing leg control mechanisms are divided into two groups, and the two landing leg control mechanisms in each group are arranged side by side left and right, and the two groups of landing leg units are installed side by side at the bottom of the helicopter. When N=5, the five landing leg control mechanisms are divided into three groups, one of which is a group, and the group of landing leg control mechanisms is a single-leg mechanism group, and the other four landing leg control mechanisms are divided into two groups, and the two groups of landing leg control mechanisms are a double-leg mechanism group, the two landing leg control mechanisms in the double-leg mechanism group are arranged side by side, and the three groups of landing leg control mechanisms are installed side by side at the bottom of the helicopter. When N=6, the six landing leg control mechanisms are divided into three groups, the two landing leg control mechanisms in each group are arranged side by side, and the three groups of landing leg control mechanisms are installed side by side at the bottom of the helicopter. The number of landing leg control mechanisms can be selected as needed, and the above arrangement can increase the stability of the helicopter when landing.

[0048] like Figure 3 , Fig. 9 , Fig.15 and Fig. 22As shown, when the landing leg unit is a single degree of freedom, each hydraulic control unit of this embodiment includes a first liquid inlet pipe 29, a first liquid outlet pipe 30, an active control oil circuit 31, a passive control oil circuit 32, a first electro-hydraulic servo valve 33 and an electromagnetic reversing valve 34 for switching between the active control oil circuit 31 and the passive control oil circuit 32. One end of the first liquid inlet pipe 29 is connected to the rod chamber of the first actuator 1, and the other end is connected to the electromagnetic reversing valve 34. One end of the first liquid outlet pipe 30 is connected to the rodless chamber of the first actuator 1, and the other end is connected to the first liquid outlet pipe 30 in the remaining hydraulic control units. In order to ensure the effective locking of the first actuator 1 during the landing process, a switch valve 40 is provided on the first liquid inlet pipe 29 and the first liquid outlet pipe 30 of the first actuator 1, so as to be opened during the adaptive adjustment process and locked after the landing is completed. The first liquid inlet pipe 29 and the first liquid outlet pipe 30 are both connected to the first electro-hydraulic servo valve 33, and the first electro-hydraulic servo valve 33 can switch the oil circuit between the rodless chamber and the rod chamber of the first actuator 1 and the first liquid inlet pipe 29 and the first liquid outlet pipe 30. The active control oil circuit 31 and the passive control oil circuit 32 are designed in parallel, and the active control oil circuit 31 is connected to the first liquid inlet pipe 29 via the electromagnetic reversing valve 34. One end of the passive control oil circuit 32 is connected to the electromagnetic reversing valve 34, and the other end is connected to the passive control oil circuit 32 in the remaining hydraulic control units. When the electromagnetic reversing valve 34 controls the passive control oil circuit 32 to be connected to the first liquid inlet pipe 29, each first actuator 1 is connected to form a closed loop via the first liquid inlet pipe 29, the passive control oil circuit 32 and the first liquid outlet pipe 30 to realize the passive differential control between each first actuator 1.

[0049] The oil tank 12 is connected to the passive control oil circuit 32 in each hydraulic control unit via the main oil circuit 13 and the first branch oil circuit 14. When the electromagnetic reversing valve 34 controls the first actuator cylinder 1 to be connected to the passive control oil circuit 32, the oil tank 12 supplies oil to each first actuator cylinder 1 to actively control the extension and retraction of the piston rod of each first actuator cylinder 1, thereby realizing active control of the landing gear.

[0050] like Figure 4 , Fig.10 , Fig.16 and Fig.23As shown, when the landing leg unit has two degrees of freedom, each hydraulic control unit of this embodiment further includes a second liquid inlet pipe 35, a second liquid outlet pipe 36 and a second electro-hydraulic servo valve 37. One end of the second liquid inlet pipe 35 is connected to the rod chamber of the second actuator 5, and the other end is connected to the oil tank 12 via the second branch oil circuit 15 and the main oil circuit 13. One end of the second liquid outlet pipe 36 is connected to the rodless chamber of the second actuator 5, and the other end is connected to the oil tank 12. In order to ensure the effective locking of the second actuator 5 during the landing process, a switch valve 40 is provided on the second liquid inlet pipe 35 and the second liquid outlet pipe 36 of the second actuator 5, so as to be opened during the adaptive adjustment process and locked after the landing is completed. The second electro-hydraulic servo valve 37 controls the switching between the second liquid inlet pipe 35 and the second liquid outlet pipe 36 and the rodless chamber and the rod chamber of the second actuator 5. During the landing of the helicopter, the oil tank 12 supplies oil to the second actuators 5 through the main oil circuit 13 and the second branch oil circuit 15 to actively control the extension and retraction of the piston rods of each second actuator 5 and couple the first actuator 1 to achieve the change of the landing leg posture.

[0051] like Figures 3 to 27 As shown, the hydraulic control circuit of this embodiment further includes a second differential oil pump 24. The second differential oil pump 24 is provided between two adjacent groups of landing leg control mechanisms. The second differential oil pump 24 is respectively connected to the active control oil circuits 31 in the two adjacent groups of landing leg control mechanisms, so that when the electromagnetic reversing valves 34 in the two adjacent groups control the active control oil circuits 31 to be connected to the first liquid inlet pipe 29, the first liquid outlet pipe 30 can connect the first actuator cylinders 1 in the front and rear groups to form a closed circuit via the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the active control oil circuit 31, and the second differential oil pump 24 is started to realize the active differential control between the front and rear groups of landing leg control mechanisms.

[0052] Among them, the active differential control between the front and rear landing leg control mechanisms includes two situations, one is the active differential control of the front group as a whole and the rear group as a whole, and the other is the active differential control of a certain landing leg control mechanism in the front group and a certain landing leg control mechanism in the rear group. When the front group as a whole and the rear group as a whole are actively differentially controlled, a second differential oil pump 24 is provided, and the second differential oil pump 24 is connected to the active control oil circuit 31 in each landing leg control mechanism. At this time, the first actuators 1 in all landing leg control mechanisms are connected to form a closed loop via the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the active control oil circuit 31, and the second differential oil pump 24 is started to realize the active differential control of the landing leg control mechanism of the front group as a whole and the landing leg control mechanism of the rear group as a whole. When a landing leg control mechanism in the front group and a landing leg control mechanism in the rear group are actively differentially controlled, each group of landing leg control mechanisms is provided with at least two landing leg control mechanisms, and when the number of landing leg control mechanisms in two adjacent groups is the same, the landing leg control mechanisms in the two adjacent groups correspond to each other one by one, and the active control oil circuit 31 between the two corresponding landing leg control mechanisms is communicated by the second differential oil pump 24. When the electromagnetic reversing valves 34 in the two corresponding landing leg control mechanisms respectively control the active control oil circuit 31 to be communicated with the first liquid inlet pipe 29, the first actuators 1 in the two corresponding landing leg control mechanisms can be connected to form a closed loop via the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the active control oil circuit 31, and the second differential oil pump 24 is started to realize the active differential control between the front and rear landing leg control mechanisms.

[0053] like Figures 3 to 21 As shown, when each landing leg control mechanism is provided with two landing leg control mechanisms, the hydraulic control circuit of this embodiment further includes a first differential oil pump 25, each landing leg control mechanism corresponds to one first differential oil pump 25, the first differential oil pump 25 is connected to the two active control oil circuits 31 in the corresponding group, when the two electromagnetic reversing valves 34 in each group respectively control the corresponding active control oil circuit 31 to be connected to the first liquid inlet pipe 29, the two first actuator cylinders 1 in the group are connected to form a closed loop via the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the active control oil circuit 31, and the first differential oil pump 25 is started to realize the active differential control between the two landing leg units in the group.

[0054] It can be seen that the landing leg unit of this embodiment is equipped with a hydraulic control circuit to realize multiple control modes of the landing gear, such as active control of the landing leg unit, passive differential control between each landing leg unit, active differential control between the front and rear groups of landing leg units, and when there are two landing leg units in each group, active differential control between the two landing leg units in the group. Such a design allows the helicopter to change the structural posture of the landing leg unit according to the terrain conditions, ensuring that the helicopter can maintain a horizontal and stable body when landing on a rugged or inclined ground.

[0055] Embodiment 1:

[0056] Fig. 9 The schematic diagram of hydraulic control of the landing gear adopting a four-leg design and the landing leg unit adopting a single degree of freedom structure is shown. Fig. 9 As shown, the hydraulic control circuit of this embodiment is provided with four hydraulic control units, and four landing leg units are provided. Each hydraulic control unit corresponds to a landing leg unit, and together with the landing leg unit, forms a landing leg control mechanism. The four landing leg control mechanisms are divided into two groups and are installed side by side from front to back at the bottom of the helicopter.

[0057] Each landing leg unit is provided with a first actuator 1, and each hydraulic control unit includes a first liquid inlet pipe 29, a first liquid outlet pipe 30, an active control oil circuit 31, a passive control oil circuit 32, a first electro-hydraulic servo valve 33 and an electromagnetic reversing valve 34 for switching the active control oil circuit 31 and the passive control oil circuit 32. One end of the first liquid inlet pipe 29 is connected to the rod chamber of the first actuator 1, and the other end is connected to the P interface of the electromagnetic reversing valve 34. One end of the first liquid outlet pipe 30 is connected to the rodless chamber of the first actuator 1, and the other end is connected to the first liquid outlet pipes 30 in the remaining hydraulic control units. In addition, the first liquid outlet pipe 30 is also connected to the oil tank 12 via the overflow valve 38 and the return oil valve 39. The return oil valve 39 is a two-position two-way electromagnetic valve. The overflow valve 38 and the return oil valve 39 can allow the excess hydraulic oil in the closed circuit to flow back to the oil tank 12. The first electro-hydraulic servo valve 33 is a three-position four-way electro-hydraulic valve. The first electro-hydraulic servo valve 33 can control the switching of the oil circuit between the rodless chamber and the rod chamber of the first actuator 1 and the first liquid inlet pipe 29 and the first liquid outlet pipe 30. Specifically, the first liquid inlet pipe 29 is divided into two sections and is set as a first liquid inlet pipe A and a first liquid inlet pipe B. The first liquid outlet pipe 30 is divided into two sections and is set as a first liquid outlet pipe A and a first liquid outlet pipe B. One end of the first liquid inlet pipe A is connected to the P interface of the electromagnetic reversing valve 34, and the other end is connected to an inlet of the first electro-hydraulic servo valve 33. One end of the first liquid inlet pipe B is connected to the rod chamber of the first actuator 1, and the other end is connected to an outlet of the first electro-hydraulic servo valve 33. One end of the first liquid outlet pipe A is connected to another inlet of the first electro-hydraulic servo valve 33, and the other end is connected to the remaining first liquid outlet pipes 30. One end of the first liquid outlet pipe B is connected to another outlet of the first electro-hydraulic servo valve 33, and the other end is connected to the rodless chamber of the first actuator 1. When the first electro-hydraulic servo valve 33 is in the left position, the first liquid inlet pipe A is connected to the first liquid inlet pipe B, and the first liquid outlet pipe A is connected to the first liquid outlet pipe B. When the first electro-hydraulic servo valve 33 is in the right position, the first liquid inlet pipe 29A is connected to the first liquid outlet pipe B, and the first liquid inlet pipe B is connected to the first liquid outlet pipe A. In this way, the rodless chamber and the rod chamber between each first actuator cylinder 1 can be adjusted to be connected. It is no longer simply that the rodless chamber is connected to the rodless chamber and the rod chamber is connected to the rod chamber. The hydraulic oil between each first actuator cylinder 1 can be better controlled to ensure the stability of the helicopter landing. One end of the passive control oil circuit 32 is connected to the A interface of the electromagnetic reversing valve 34 so that the passive control oil circuit 32 can be connected to the first liquid inlet pipe 29, and the other end of the passive control oil circuit 32 is connected to the passive control oil circuits 32 in the remaining hydraulic control units; when the electromagnetic reversing valve 34 controls the passive control oil circuit 32 to be connected to the first liquid inlet pipe 29, each first actuator cylinder 1 is connected to form a closed loop via the first liquid inlet pipe 29, the passive control oil circuit 32 and the first liquid outlet pipe 30 to realize passive differential control between each first actuator cylinder 1.

[0058] The active control mode of the landing leg unit is realized as follows: before the helicopter lands, the oil closing valve 16 and the oil return valve 39 are opened, and all the electromagnetic reversing valves 34 are switched to the A interface. At this time, the first actuator 1 is connected to the oil tank 12 via the first inlet pipe 29, the passive control oil circuit 32, the first branch oil circuit 14 and the main oil circuit 13, and the one-way hydraulic pump 19 is turned on, and the hydraulic oil in the oil tank 12 is pumped into the first actuator 1. The extension or retraction of the piston rod of the first actuator 1 is controlled by the first electro-hydraulic servo valve 33. When the first electro-hydraulic servo valve 33 is in the left position, the hydraulic oil is pumped into the rod cavity of the first actuator 1, and the piston rod of the first actuator 1 is retracted. When the first electro-hydraulic servo valve 33 is in the right position, the hydraulic oil is pumped into the rodless cavity of the first actuator 1, and the piston rod of the first actuator 1 is extended, thereby adjusting the extension length of each first actuator 1 to adapt to the rugged terrain. The oil flowing out of each first actuator 1 converges and flows back to the oil tank 12 through the return valve. The overflow valve 38 is used to ensure that the hydraulic oil pressure of the side swing circuit and the lifting circuit is within the normal working range. This control mode can actively adjust the posture of each leg according to the topography of the ground to ensure that the helicopter can keep the fuselage level when landing. In addition, the main control mode is also used for the leg retraction action and controlling the initial height of the legs before landing, so as to switch to other control modes.

[0059] The passive differential control mode is implemented as follows: Fig.12 The passive differential control mode of this embodiment is shown. Before the helicopter lands, the lengths of the piston rods of all first actuators 1 are controlled to be the same through the active control mode. At this time, all first actuators 1 are at the same height, and the oil closing valve 16 cuts off the oil supply relationship between the oil tank 12 and the first actuator 1. Fig.12As shown, the oil return valve 39 is powered off, the first electro-hydraulic servo valve 33 in the four landing leg control mechanisms is switched to the left position, and all the electromagnetic reversing valves 34 are switched to the A interface. At this time, all the first actuators 1 are connected to form a closed loop through the passive control oil circuit 32, the first liquid inlet pipe 29 and the first liquid outlet pipe 30. The total amount of hydraulic oil in the closed loop remains unchanged, and the set pressure of the overflow valve 38 is adjusted to a higher value to ensure the normal function of the control closed loop while preventing excessive pressure from damaging the closed loop. When the helicopter lands, the one-way hydraulic pump 19 is started, and the hydraulic oil in the oil tank 12 is pumped into the four second actuators 5. The piston rod of the first actuator 1 in the landing leg unit that touches the ground first is stressed and moves toward the rodless cavity side, and the hydraulic oil in the rodless cavity of the first actuator 1 is pressed into the rodless cavity of the first actuator 1 in the remaining landing leg units that have not touched the ground through the first liquid outlet pipe 30. The piston rod of the first actuator 1 in the landing leg unit that has not touched the ground extends out and touches the ground under the pressure of the hydraulic oil. At the same time, the hydraulic oil in the rod cavity of the first actuator 1 in the landing leg unit that has not touched the ground is squeezed into the rod cavity of the first actuator 1 in the landing leg unit that has not touched the ground through the passive control oil circuit 32 and the first liquid inlet pipe 29 to ensure the circuit pressure balance. At this time, all the landing legs of the helicopter touch the ground, and at the same time, the movement of the second actuator 5 is coupled to prevent the foot end from slipping during the movement of the first actuator 1, thereby achieving a stable landing of the helicopter. It can be seen that this embodiment relies on the hydraulic oil in the entire closed loop to complete the differential drive of the four first actuators 1. The driving force comes from the ground support force exerted on the first actuators 1 in one or some of the landing leg units that touch the ground first. The passive differential control between the first actuators 1 can increase the terrain adaptive capability of the helicopter. And this control mode can ensure that the helicopter can effectively maintain the level of the body in complex terrain or dynamically changing landing scenes (such as the shaking of the ship deck when the ship-borne helicopter lands), thereby improving the safety and stability of the helicopter landing.

[0060] like Fig. 9 As shown, the active control oil circuit 31 and the passive control oil circuit 32 of this embodiment are designed in parallel, and one end of the active control oil circuit 31 is connected to the B interface of the electromagnetic reversing valve 34, so that the active control oil circuit 31 can be connected to the first liquid inlet pipe 29. The hydraulic control circuit of this embodiment is also provided with a first differential oil pump 25, and two first differential oil pumps 25 are provided. Each group of landing leg control mechanisms corresponds to one first differential oil pump 25, and the first differential oil pump 25 is connected to the two active control oil circuits 31 in the group. When the two electromagnetic reversing valves 34 in the group respectively control the active control oil circuit 31 to be connected to the first liquid inlet pipe 29, the two first actuators 1 in the group are connected to form a closed loop via the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the active control oil circuit 31, and the first differential oil pump 25 is started to realize the active differential control between the two landing leg units in the group.

[0061] The implementation process of active differential control of left and right legs is: Fig.13 The active differential control mode of the left and right legs of this embodiment is shown, combined with Fig.13 Before the helicopter lands, all the first actuators 1 are controlled to be at the same height through the active control mode, and the oil closing valve 16 cuts off the oil supply relationship between the oil tank 12 and the first actuator 1. The return oil valve 39 is powered off, each first electro-hydraulic servo valve 33 is switched to the left position, and all electromagnetic reversing valves 34 are switched to the B interface. At this time, the two active control oil circuits 31 in each group are connected through the first differential oil pump 25, and are connected to the first liquid inlet pipes 29 of the two first actuators 1, that is, the left and right first actuators 1 form a closed loop through the first liquid inlet pipe 29, the active control oil circuit 31 and the first liquid outlet pipe 30. The total amount of hydraulic oil in the closed loop remains unchanged, and the overflow valve 38 is set to a higher value to ensure that the closed loop function is normal while preventing excessive pressure from damaging the closed loop. When the helicopter lands, the one-way hydraulic pump 19 is started, and the hydraulic oil in the oil tank 12 is pumped into the second actuator 5. Start the two first differential oil pumps 25, each first differential oil pump 25 pumps the hydraulic oil in the corresponding left (right) first actuator 1 into the right (left) first actuator 1 through the active control oil circuit 31 and the first liquid inlet pipe 29, and at the same time, the hydraulic oil in the right (left) first actuator 1 is pressed into the left (right) first actuator 1 through the first liquid outlet pipe 30 to ensure the circuit pressure balance. At this time, all the landing legs of the helicopter touch the ground. It can be seen from this that this embodiment is also an active control mode, but this control mode relies on the hydraulic oil in the entire closed loop and the first differential oil pump 25 to drive the piston rods of the left and right first actuators 1 to extend and retract, so as to realize the active differential control between the left and right first actuators 1. The active differential control between each first actuator 1 can increase the terrain adaptability of the helicopter. And this control mode can ensure that the helicopter can effectively maintain the level of the body in complex terrain or dynamically changing landing scenes (such as the shaking of the ship deck when the ship-borne helicopter lands), and improve the safety and stability of the helicopter landing. In addition, this control mode can save driving force and reduce energy consumption compared to the active control mode using the hydraulic oil in the oil tank 12. Before the helicopter lands, if the active control mode is used to directly control the action of the first actuator 1 to adjust the attitude of the helicopter, a large power consumption is required, which increases the weight of the helicopter. On the contrary, if the active control mode is only used to complete the simple action of retracting the first actuator 1, the required pressure is relatively small.

[0062] like Fig. 9As shown, the two adjacent groups of landing leg control mechanisms in this embodiment are provided with a first series oil circuit 26, a second differential oil pump 24 and a parallel oil circuit 27. There are two parallel oil circuits 27, which are arranged one by one corresponding to the two adjacent groups of landing leg control mechanisms. Each parallel oil circuit 27 is arranged in parallel with the first differential oil pump 25 in the corresponding group, and both ends of each parallel oil circuit 27 are connected to the two active control oil circuits 31 in the corresponding group; there is one first series oil circuit 26, which is connected to the two parallel oil circuits 27, and the second differential oil pump 24 is arranged at When the first series oil circuit 26 controls the first actuator 1 to be connected to the active control oil circuit 31 by the electromagnetic reversing valve 34, all the first actuators 1 of the two adjacent groups are connected to form a closed loop via the first liquid inlet pipe 29, the active control oil circuit 31, the parallel oil circuit 27, the first series oil circuit 26 and the first liquid outlet pipe 30, and the second differential oil pump 24 is started to pump the hydraulic oil in all the first actuators 1 in one group to all the first actuators 1 in the other group, so as to realize the active differential control between the first actuators 1 in the two adjacent groups of landing leg control mechanisms.

[0063] The implementation process of active differential control of two adjacent sets of landing leg control mechanisms is as follows: Fig.14 The active differential control mode of the front and rear legs of this embodiment is shown. Before the helicopter lands, all the first actuators 1 are controlled to be at the same height through the active control mode, and the oil closing valve 16 cuts off the oil supply relationship between the oil tank 12 and the first actuator 1. Fig.14As shown, the oil return valve 39 is powered off, all the first electro-hydraulic servo valves 33 are switched to the left position, and all the electromagnetic reversing valves 34 are switched to the B interface. At this time, the active control oil circuit 31 is connected to the first liquid inlet pipe 29 connecting the two first actuators 1. When the helicopter lands, the one-way hydraulic pump 19 is started, and the hydraulic oil in the oil tank 12 is pumped into the second actuator 5. The second differential oil pump 24 is started, and the second differential oil pump 24 pumps the hydraulic oil in all the first actuators 1 of the front group (rear group) through the first series oil circuit 26, the parallel oil circuit 27, the active control oil circuit 31 and the first liquid inlet pipe 29 to all the first actuators 1 of the rear group (front group). At the same time, the hydraulic oil in all the first actuators 1 of the rear group (front group) is pressed into all the first actuators 1 of the front group (rear group) through the first liquid outlet pipe 30 to ensure the circuit pressure balance. At this time, all the landing legs of the helicopter touch the ground, and the helicopter can land stably. It can be seen from this that this embodiment is also an active control mode. The front and rear groups of first actuator cylinders 1 are connected through the first series oil circuit 26, the parallel oil circuit 27, the active control oil circuit 31 and the first liquid inlet pipe 29 to form a closed loop. The total amount of hydraulic oil in the closed loop remains unchanged, and the overflow valve 38 is set to a higher value to ensure that the closed loop function is normal while preventing excessive pressure from damaging the closed loop. This embodiment relies on the hydraulic oil in the entire closed loop and the second differential oil pump 24 to drive the piston rods of the front and rear groups of first actuator cylinders 1 to extend or retract, so as to achieve active differential control between the front and rear groups of first actuator cylinders 1. The active differential control between the front and rear groups of first actuator cylinders 1 can increase the terrain adaptability of the helicopter, ensure that the helicopter can effectively maintain the level of the body in complex terrain or dynamically changing landing scenes, and improve the safety and stability of helicopter landing.

[0064] Embodiment 2:

[0065] Fig.10 The figure shows a hydraulic control schematic diagram of a landing gear adopting a four-leg design and a landing leg unit adopting a two-degree-of-freedom structure, as shown in FIG. Fig.10As shown, the difference between this embodiment and embodiment 1 is that the landing leg unit of this embodiment also includes a second actuator 5, and each hydraulic control unit of this embodiment also includes a second liquid inlet pipe 35, a second liquid outlet pipe 36 and a second electro-hydraulic servo valve 37. One end of the second liquid inlet pipe 35 is connected to the rod chamber of the second actuator 5, and the other end is connected to the oil tank 12 via the main oil circuit 13 and the second branch oil circuit 15. The second liquid outlet pipe 36 connects the rodless chamber of the second actuator 5 with the oil tank 12, and the second electro-hydraulic servo valve 37 is a three-position four-way electro-hydraulic valve. The second electro-hydraulic servo valve 37 can switch the oil circuit between the rodless chamber and the rod chamber of the second actuator 5 and the second first liquid inlet pipe 29 and the second oil outlet pipe. The specific connection method is the same as the connection method of the first actuator 1, the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the first electro-hydraulic servo valve 33. When the helicopter lands, the oil tank 12 is connected to the second actuator 5 via the main oil circuit 13 and the second branch oil circuit 15, and the one-way hydraulic pump 19 is turned on. The hydraulic oil in the oil tank 12 is pumped into the second actuator 5 to realize the active control of the second actuator 5. The oil of each second actuator 5 flows out of the second electro-hydraulic servo valve 37 and then flows back to the oil tank 12. The extension or retraction of the piston rod of the second actuator 5 is controlled by the second electro-hydraulic servo valve 37. When the second electro-hydraulic servo valve 37 is in the left position, the hydraulic oil is pumped into the rod cavity of the second actuator 5, and the piston rod of the second actuator 5 is retracted. When the second electro-hydraulic servo valve 37 is in the right position, the hydraulic oil is pumped into the rodless cavity of the second actuator 5, and the piston rod of the second actuator 5 is extended, thereby adjusting the posture of the landing leg. The landing leg is coupled with the movement of the second actuator 5 to prevent the foot end from slipping during the movement of the landing leg, so as to realize the stable landing of the helicopter. The first actuator 1 is the same as that in the first embodiment whether it adopts the active control mode, the passive differential control mode or the active differential control mode.

[0066] Embodiment 3:

[0067] Fig.15 The figure shows a hydraulic control schematic diagram of a landing gear adopting a six-leg design and a landing leg unit adopting a single degree of freedom structure, as shown in FIG. Fig.15 As shown, the difference between this embodiment and embodiment 1 is that this embodiment is provided with six landing leg units and six hydraulic control units, each hydraulic control unit corresponds to one landing leg unit, and is configured with the landing leg unit as a landing leg control mechanism, and the six landing leg control mechanisms are divided into three groups and are installed side by side from front to back at the bottom of the helicopter. The rest of the design remains unchanged.

[0068] Embodiment 4:

[0069] Fig.16 The figure shows a hydraulic control schematic diagram of a landing gear adopting a six-leg design and a landing leg unit adopting a two-degree-of-freedom structure. Fig.16As shown, the difference between this embodiment and embodiment 2 is that this embodiment is provided with six landing leg units and six hydraulic control units, each hydraulic control unit corresponds to one landing leg unit, and is configured with the landing leg unit as a landing leg control mechanism, and the six landing leg control mechanisms are divided into three groups and are installed side by side from front to back at the bottom of the helicopter. The rest of the design remains unchanged.

[0070] Embodiment 5:

[0071] Fig. 22 Another hydraulic control schematic diagram is shown in which the landing gear adopts a four-leg design and the landing leg unit adopts a single degree of freedom structure. The difference between this embodiment and embodiment 1 is that no differential oil pump is set between the two landing leg control mechanisms in each group, and the design method of the differential oil pump between the front and rear landing leg control mechanisms is different from that in embodiment 1. In order to clearly express the connection relationship, the two landing leg control mechanisms of each landing leg control mechanism in this embodiment are respectively referred to as the left leg and the right leg. Fig. 22 As shown, the two adjacent landing leg control mechanisms in this embodiment are provided with a second series oil circuit 28 and a second differential oil pump 24. There are two second series oil circuits 28, one of which is connected to the active control oil circuit 31 of the left front leg and the active control oil circuit 31 of the rear right leg. There are two second differential oil pumps 24, and one second differential oil pump 24 is provided. When the electromagnetic reversing valve 34 controls the first actuator 1 to be connected to the active control oil circuit 31, the first actuator 1 of the left front leg and the first actuator 1 of the right rear leg are connected to form a closed loop via the first oil inlet pipe, the first oil outlet pipe, the active control oil circuit 31 and the second series oil circuit 28, and the second differential oil pump 24 is started to pump the hydraulic oil in the first actuator 1 of the left front leg into the first actuator 1 of the right rear leg, so as to realize the active differential control between the left front leg and the right rear leg. Another second series oil circuit 28 connects the active control oil circuit 31 of the right front leg with the active control oil circuit 31 of the left hind leg. When the electromagnetic reversing valve 34 controls the first actuator 1 to be connected with the active control oil circuit 31, the first actuator 1 of the right front leg and the first actuator 1 of the left hind leg are connected to form a closed loop via the first oil inlet pipe, the first oil outlet pipe, the active control oil circuit 31 and the second series oil circuit 28. The second differential oil pump 24 is started to pump the hydraulic oil in the first actuator 1 of the right front leg into the first actuator 1 in the left hind leg to realize active differential control between the right front leg and the left hind leg.

[0072] The process of implementing the active differential control mode of the front and rear legs is as follows: before the helicopter lands, all the first actuators 1 are controlled to be at the same height through the active control mode, and the oil closing valve 16 cuts off the oil supply relationship between the oil tank 12 and the first actuator 1. The return oil valve 39 is powered off, all the first electro-hydraulic servo valves 33 are switched to the left position, and all the electromagnetic reversing valves 34 are switched to the B interface. At this time, the first inlet pipe 29, the first outlet pipe 30, the active control oil circuit 31 and the second series oil circuit 28 connect the two first actuators 1 of the left front leg and the right rear leg. The two second differential oil pumps 24 are started, and one of the second differential oil pumps 24 pumps the hydraulic oil in the first actuator 1 in the left front leg to the first actuator 1 in the right rear leg through the second series oil circuit 28, the active control oil circuit 31 and the first inlet pipe 29, and at the same time, the hydraulic oil in the first actuator 1 in the right rear leg is pressed into the first actuator 1 in the left front leg through the first outlet pipe 30 to ensure the circuit pressure balance. Another second differential oil pump 24 pumps the hydraulic oil in the first actuator 1 in the right front leg to the first actuator 1 in the left rear leg through the second series oil circuit 28, the active control oil circuit 31 and the first liquid inlet pipe 29, and at the same time, the hydraulic oil in the first actuator 1 in the left rear leg is pressed into the first actuator 1 in the right front leg through the first liquid outlet pipe 30 to ensure the circuit pressure balance. At this time, all landing legs of the helicopter touch the ground, achieving a stable landing of the helicopter.

[0073] The principles of the remaining active control modes and passive differential control modes are the same as those in Embodiment 1 and will not be described again here.

[0074] Embodiment 6:

[0075] Fig.23Another hydraulic control schematic diagram is shown in which the landing gear adopts a four-leg design and the landing leg unit adopts a two-degree-of-freedom structure. The difference between this embodiment and embodiment 5 is that the landing leg unit of this embodiment further includes a second actuator 5, and each hydraulic control unit of this embodiment further includes a second liquid inlet pipe 35, a second liquid outlet pipe 36, and a second electro-hydraulic servo valve 37. One end of the second liquid inlet pipe 35 is connected to the rod chamber of the second actuator 5, and the other end is connected to the oil tank 12 via the main oil circuit 13 and the second branch oil circuit 15. The second liquid outlet pipe 36 connects the rodless chamber of the second actuator 5 and the oil tank 12. The second electro-hydraulic servo valve 37 is a three-position four-way electro-hydraulic valve. The second electro-hydraulic servo valve 37 can switch the oil circuit between the rodless chamber and the rod chamber of the second actuator 5 and the second first liquid inlet pipe 29 and the second oil outlet pipe. The specific connection method is the same as the connection method of the first actuator 1, the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the first electro-hydraulic servo valve 33. When the helicopter lands, the oil tank 12 is connected to the second actuator 5 via the main oil circuit 13 and the second branch oil circuit 15, and the one-way hydraulic pump 19 is turned on. The hydraulic oil in the oil tank 12 is pumped into the second actuator 5 to realize the active control of the second actuator 5. The oil of each second actuator 5 flows out of the second electro-hydraulic servo valve 37 and then flows back to the oil tank 12. The extension or retraction of the piston rod of the second actuator 5 is controlled by the second electro-hydraulic servo valve 37. When the second electro-hydraulic servo valve 37 is in the left position, the hydraulic oil is pumped into the rod cavity of the second actuator 5, and the piston rod of the second actuator 5 is retracted. When the second electro-hydraulic servo valve 37 is in the right position, the hydraulic oil is pumped into the rodless cavity of the second actuator 5, and the piston rod of the second actuator 5 is extended, thereby adjusting the posture of the landing leg. The landing leg is coupled with the movement of the second actuator 5 to prevent the foot end from slipping during the movement of the landing leg, so as to realize the stable landing of the helicopter. The first actuator 1 is the same as that in the fifth embodiment whether it adopts the active control mode, the passive differential control mode or the active differential control mode.

[0076] Embodiment 7:

[0077] Figure 3 The figure shows a hydraulic control schematic diagram of a landing gear adopting a three-leg design and a landing leg unit adopting a single degree of freedom structure, as shown in FIG. Figure 3As shown, since one landing leg control mechanism in this embodiment is designed with only one leg, this embodiment is different from Embodiment 1 in that there is only one parallel oil circuit 27 between the front and rear landing leg control mechanisms. The parallel oil circuit 27 connects the two active control oil circuits 31 in the double-leg mechanism group and is designed in parallel with the first differential oil pump 25. The first series oil circuit 26 connects the parallel oil circuit 27 with the active control oil circuit 31 in the single-leg mechanism group. When the electromagnetic reversing valve 34 controls the first actuator 1 to be connected with the active control oil circuit 31, at this time, all the first actuators 1 in the front and rear adjacent groups are connected to form a closed loop via the first liquid inlet pipe 29, the active control oil circuit 31, the parallel oil circuit 27, the first series oil circuit 26 and the first liquid outlet pipe 30, and the second differential oil pump 24 is started to pump the hydraulic oil in all the first actuators 1 in the front (rear) group into all the first actuators 1 in the rear (front) group, so as to realize the active differential control between the first actuators 1 in the two adjacent landing leg control mechanisms.

[0078] The principles of the active control mode, the passive differential control mode and the active differential control mode of this embodiment are the same as those of the first embodiment.

[0079] Embodiment 8:

[0080] Figure 4 The figure shows a hydraulic control schematic diagram of a landing gear adopting a three-leg design and a landing leg unit adopting a two-degree-of-freedom structure, as shown in FIG. Figure 4As shown, the difference between this embodiment and embodiment 7 is that the landing leg unit of this embodiment also includes a second actuator 5, and each hydraulic control unit of this embodiment also includes a second liquid inlet pipe 35, a second liquid outlet pipe 36 and a second electro-hydraulic servo valve 37. One end of the second liquid inlet pipe 35 is connected to the rod chamber of the second actuator 5, and the other end is connected to the oil tank 12 via the main oil circuit 13 and the second branch oil circuit 15. The second liquid outlet pipe 36 connects the rodless chamber of the second actuator 5 with the oil tank 12, and the second electro-hydraulic servo valve 37 is a three-position four-way electro-hydraulic valve. The second electro-hydraulic servo valve 37 can switch the oil circuit between the rodless chamber and the rod chamber of the second actuator 5 and the second first liquid inlet pipe 29 and the second oil outlet pipe. The specific connection method is the same as the connection method of the first actuator 1, the first liquid inlet pipe 29, the first liquid outlet pipe 30 and the first electro-hydraulic servo valve 33. When the helicopter lands, the oil tank 12 is connected to the second actuator 5 via the main oil circuit 13 and the second branch oil circuit 15, and the one-way hydraulic pump 19 is turned on. The hydraulic oil in the oil tank 12 is pumped into the second actuator 5 to realize the active control of the second actuator 5. The oil of each second actuator 5 flows out of the second electro-hydraulic servo valve 37 and then flows back to the oil tank 12. The extension or retraction of the piston rod of the second actuator 5 is controlled by the second electro-hydraulic servo valve 37. When the second electro-hydraulic servo valve 37 is in the left position, the hydraulic oil is pumped into the rod cavity of the second actuator 5, and the piston rod of the second actuator 5 is retracted. When the second electro-hydraulic servo valve 37 is in the right position, the hydraulic oil is pumped into the rodless cavity of the second actuator 5, and the piston rod of the second actuator 5 is extended, thereby adjusting the posture of the landing leg. The landing leg is coupled with the movement of the second actuator 5 to prevent the foot end from slipping during the movement of the landing leg, so as to realize the stable landing of the helicopter. The first actuator 1 is the same as that in the seventh embodiment whether it adopts the active control mode, the passive differential control mode or the active differential control mode.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A hydraulic control circuit with active and passive differential control, characterized in that: It includes a hydraulic control unit, wherein N hydraulic control units are provided, N ≥ 3, each hydraulic control unit corresponds to a landing leg unit, and is configured with the landing leg unit as a landing leg control mechanism, the N landing leg control mechanisms are divided into M groups and arranged side by side, M ≥ 2, and each landing leg unit is provided with a first actuator; Each hydraulic control unit includes a first liquid inlet pipe, a first liquid outlet pipe, an active control oil circuit, a passive control oil circuit, a first electro-hydraulic servo valve and an electromagnetic reversing valve for switching the active control oil circuit and the passive control oil circuit. One end of the first liquid inlet pipe is connected to the rod chamber of the first actuator cylinder, and the other end is connected to the electromagnetic reversing valve. One end of the first liquid outlet pipe is connected to the rodless chamber of the first actuator cylinder, and the other end is connected to the first liquid outlet pipes in the remaining hydraulic control units. The first liquid inlet pipe and the first liquid outlet pipe are both connected to the first electro-hydraulic servo valve. The first electro-hydraulic servo valve can switch the rodless chamber of the first actuator cylinder. The passive control oil circuit is connected to the electromagnetic reversing valve at one end and the passive control oil circuit in the other hydraulic control units at the other end; when the electromagnetic reversing valve controls the passive control oil circuit to be connected to the first liquid inlet pipe, each first actuator cylinder is connected to form a closed loop via the first liquid inlet pipe, the passive control oil circuit and the first liquid outlet pipe to realize the passive differential control between each first actuator cylinder; the active control oil circuit is designed to be connected in parallel with the passive control oil circuit, and the active control oil circuit is connected to the first liquid inlet pipe via the electromagnetic reversing valve; A second differential oil pump is provided between two adjacent groups of landing leg control mechanisms. The second differential oil pump is respectively connected to the active control oil circuits in the two adjacent groups of landing leg control mechanisms, so that when the electromagnetic reversing valves in the two adjacent groups control the active control oil circuit to be connected to the first liquid inlet pipe, the first actuator cylinders in the front and rear groups can be connected to form a closed loop via the first liquid inlet pipe, the first liquid outlet pipe and the active control oil circuit, and the second differential oil pump is started to realize active differential control between the front and rear groups of landing leg control mechanisms.

2. The active and passive differential control hydraulic control circuit according to claim 1, characterized in that: When each group of landing leg control mechanisms is provided with two landing leg control mechanisms, a first differential oil pump is provided between the two first actuator cylinders in the group, and the first differential oil pump is connected to the two active control oil circuits in the group. When the two solenoid reversing valves in the group respectively control the active control oil circuit to be connected to the first liquid inlet pipe, the two first actuator cylinders in the group are connected to form a closed loop via the first liquid inlet pipe, the first liquid outlet pipe and the active control oil circuit, and the first differential oil pump is started to realize active differential control between the two landing leg units in the group.

3. The active and passive differential control hydraulic control circuit according to claim 1, characterized in that: When each group of landing leg control mechanisms is provided with at least two landing leg control mechanisms, and the number of landing leg control mechanisms in two adjacent groups is the same, the landing leg control mechanisms in the two adjacent groups correspond to each other one by one, and the active control oil circuits between the two corresponding landing leg control mechanisms are connected by a differential oil pump. When the electromagnetic reversing valves in the two corresponding landing leg control mechanisms respectively control the active control oil circuits to be connected with the first liquid inlet pipe, the first actuator cylinders in the two corresponding landing leg control mechanisms can be connected to form a closed loop via the first liquid inlet pipe, the first liquid outlet pipe and the active control oil circuit, and the differential oil pump is started to realize active differential control between the front and rear landing leg control mechanisms.

4. The active and passive differential control hydraulic control circuit according to claim 1, characterized in that: A series oil circuit, a parallel oil circuit and a second differential oil pump are provided between two adjacent groups of landing leg control mechanisms. Two parallel oil circuits are provided, and the two parallel oil circuits are provided in one-to-one correspondence with the two adjacent groups of landing leg control mechanisms. Each parallel oil circuit is provided in parallel with the first differential oil pump in the corresponding group, and both ends of each parallel oil circuit are connected to the two active control oil circuits in the corresponding group. One series oil circuit is provided, and the series oil circuit connects the two parallel oil circuits. The second differential oil pump is provided in the series oil circuit. When the electromagnetic reversing valve controls the first actuator cylinder to be connected with the active control oil circuit, all the first actuator cylinders of the front and rear adjacent groups are connected to form a closed loop via the first liquid inlet pipe, the active control oil circuit, the parallel oil circuit, the series oil circuit and the first liquid outlet pipe. The second differential oil pump is started to pump the hydraulic oil in all the first actuator cylinders in one group into all the first actuator cylinders in the other group, so as to realize the active differential control between the first actuator cylinders in the two adjacent groups of landing leg control mechanisms.

5. A hydraulic control circuit for active and passive differential control according to claim 1, 2, 3 or 4, characterized in that: The hydraulic control circuit also includes an oil tank, which is connected to the passive control oil circuit in each hydraulic control unit. When the electromagnetic reversing valve controls the first actuator to be connected to the passive control oil circuit, the oil tank supplies oil to each first actuator to actively control the extension and retraction of the piston rod of each first actuator.

6. The active and passive differential control hydraulic control circuit according to claim 5, characterized in that: Each landing leg unit also includes a second actuator, and each hydraulic control unit also includes a second liquid inlet pipe, a second liquid outlet pipe and a second electro-hydraulic servo valve. The second liquid inlet pipe connects the rod chamber of the second actuator and the oil tank, and the second liquid outlet pipe connects the rodless chamber of the second actuator and the oil tank. The second electro-hydraulic servo valve controls the switching between the second liquid inlet pipe and the second liquid outlet pipe and the rodless chamber and the rod chamber of the second actuator.

7. A helicopter landing gear with active and passive differential control, characterized in that: The invention comprises a landing gear body, a landing leg unit and a hydraulic control circuit of active and passive differential control as claimed in claim 6, wherein the landing leg unit is installed on the landing gear body.

8. The helicopter landing gear with active and passive differential control according to claim 7, characterized in that: The cylinder body of the second actuating cylinder is connected to the landing gear body, and the end of the piston rod of the second actuating cylinder is connected to the cylinder body of the first actuating cylinder.

9. The helicopter landing gear with active and passive differential control according to claim 7, characterized in that: The landing leg unit also includes a second connecting rod, a third connecting rod and a second landing leg, one end of the second connecting rod is hinged to the landing gear body, and the other end is hinged to the middle position of the second landing leg, the cylinder body of the first actuator is hinged to the landing gear body via the third connecting rod, the end of the piston rod of the first actuator is hinged to the middle position of the second connecting rod, the cylinder body of the second actuator is hinged to the third connecting rod, and the end of the piston rod of the second actuator is hinged to the top of the second landing leg.

10. The helicopter landing gear with active and passive differential control according to claim 7, characterized in that: The landing leg unit also includes a fourth connecting rod, a fifth connecting rod and a third landing leg, one end of the fourth connecting rod is hinged to the landing gear body, and the other end is hinged to the top end of the third landing leg, the cylinder body of the first actuator cylinder is hinged to the landing gear body, the end of the piston rod of the first actuator cylinder is hinged to the fourth connecting rod, the cylinder body of the second actuator cylinder is hinged to the fourth connecting rod, the end of the piston rod of the second actuator cylinder is hinged to one end of the fifth connecting rod, and the other end of the fifth connecting rod is fixedly connected to the third landing leg.

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