An adaptive torsional damper and an aircraft

Abstract

The application belongs to the field of vibration control and relates to an adaptive torsional damper for a variable speed helicopter rotor, a torque transmission path and a transmission system and an aircraft. The damper comprises: an outer ring inner wall connected to a center hole inner ring outer wall through N groups of centrifugal grooves; the center ring is installed on a rotating part through the center hole inner ring and rotates together with the rotating part; N is a natural number greater than or equal to 2; there are N groups of first-stage springs, second-stage springs, second-stage mass blocks and friction mass block assemblies, which are arranged in the N groups of centrifugal grooves respectively; one end of the second-stage spring is connected to the center hole inner ring outer wall, the other end of the second-stage spring is connected to the inner side of the mass block, the outer side of the mass block is connected to one end of the first-stage spring, and the other end of the first-stage spring is connected to the friction mass block assembly; the outer ring is provided with an annular groove penetrating through the inner and outer end faces of the outer ring, an inner friction ring is arranged in the annular groove, and the inner friction ring is connected to the outer ring through a sliding unit and rotates in a sliding mode along the annular groove.

Description

Technical Field

[0001] This invention belongs to the field of vibration control and relates to an adaptive torsional vibration damper for variable speed helicopter rotors, torque transmission paths and transmission systems, and an aircraft. Background Technology

[0002] Traditional helicopter rotors are typically designed with a fixed rotational speed. However, with the development of electric rotor technology and the emergence of new helicopter configurations, variable rotational speed technology has gradually been researched and applied in the field of new rotor design. Variable rotational speed rotor technology allows for configuration of the rotor's overall lift-to-drag ratio under different flight conditions, improving the helicopter's climb performance, payload, and service ceiling. It also significantly enhances rotor performance and endurance, effectively reducing rotor aerodynamic noise. Furthermore, variable rotational speed rotor technology can improve helicopter fuel economy by extending the lifespan of the helicopter, engine (motor), and transmission system.

[0003] Traditional helicopter vibration is characterized by a superposition of typical KNΩ periodic and random vibrations. Meanwhile, the rotor, as the primary lift system, is the main source of vibration loads, especially the NΩ vibration loads related to the number of rotor blades and rotational speed, which cause airframe vibrations. Within the frequency range of interest in helicopter vibration prediction and control, this becomes a critical technology significantly affecting helicopter performance and function. The rotor's vibration loads combine into six components of force and torque at the rotor hub, which are transmitted to the airframe through transmission systems and other pathways, making it the primary source of overall helicopter vibration.

[0004] However, the variable rotor speed of a helicopter results in a change in its principal vibration frequency. Furthermore, the rotor's speed changes in real time, and the rate of change of speed affects the vibration at the instant of the speed change. This causes the excitation frequency of the variable-speed rotor helicopter to be unstable and results in torsional vibration in the torsional direction. Traditional fixed-frequency vibration dampers are no longer sufficient for vibration control in variable-speed rotor helicopters. Summary of the Invention

[0005] The purpose of this invention is to solve at least one of the above-mentioned technical problems. This invention provides an adaptive torsional vibration damper for variable speed helicopter rotors, torque transmission paths and transmission systems, and an aircraft, which suppresses torsional vibration loads as the speed changes and during variable speed processes, while also having the function of absorbing vibration loads in the plane perpendicular to the axis.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] An adaptive torsional damper includes: a central ring, a primary spring, a secondary spring, a secondary mass block, a friction mass block assembly, and an inner friction ring;

[0008] The central ring includes: an outer ring, a concentric inner ring with a central hole, and N sets of centrifugal grooves; the inner wall of the outer ring is connected to the outer wall of the inner ring with the central hole through the N sets of centrifugal grooves; the central ring is mounted on the rotating component through the inner ring with the central hole and rotates together with the rotating component; N is a natural number greater than or equal to 2;

[0009] The primary spring, secondary spring, secondary mass block, and friction mass block assembly each consist of N sets, which are respectively arranged in N sets of centrifugal tanks; one end of the secondary spring is connected to the outer wall of the inner ring of the central hole, and the other end is connected to the inner side of the mass block, the outer side of the mass block is connected to one end of the primary spring, and the other end of the primary spring is connected to the friction mass block assembly.

[0010] The outer ring has an annular groove that runs through the inner and outer end faces of the outer ring. The inner friction ring is disposed in the annular groove and is connected to the outer ring through a sliding unit and rotates along the annular groove in a sliding manner.

[0011] Furthermore, the centrifuge tank is equipped with a slide rail, and the secondary mass block moves radially along the slide rail under the action of centrifugal force.

[0012] Furthermore, the N sets of centrifuge tanks are evenly distributed circumferentially to avoid eccentricity.

[0013] Furthermore, N is 4.

[0014] Furthermore, the sliding unit is a ball bearing to minimize friction between the inner friction ring and the outer ring.

[0015] Furthermore, the inner surface of the inner friction ring is made of wear-resistant material to form a wear-resistant surface; the wear-resistant material can be high manganese steel, wear-resistant high chromium cast iron, or wear-resistant alloy steel, to reduce friction loss and heat generation.

[0016] The primary spring is always in a compressed state, pressing the friction mass assembly onto the inner friction ring, resulting in frictional contact between the friction mass assembly and the inner friction ring. This reduces the nonlinear phenomenon of the primary spring transitioning from a compressed to a stretched state.

[0017] Furthermore, the friction mass block assembly includes a friction plate and a sliding frame; the sliding frame is connected to a primary spring, and the friction plate is connected to the outside of the sliding frame, with the friction plate in frictional contact with the inner friction ring. The friction plate is made of powder metallurgy material and has good wear resistance.

[0018] Furthermore, the formulas for calculating the stiffness k1 of the primary spring, the stiffness k2 of the secondary spring, and the mass m of the secondary mass block are as follows:

[0019]

[0020] This represents the initial pressure between the friction plate and the inner friction ring.

[0021] The rotational speed at which the rotating component rotates at a constant speed;

[0022] Let be the moment of inertia of the internal friction ring;

[0023] The rotational angular acceleration of the rotating component;

[0024] The internal friction ring is subjected to external damping force;

[0025] This refers to the frictional force between the friction plate and the inner friction ring.

[0026] This is the maximum static friction force between the friction plate and the inner friction ring;

[0027] , These refer to the masses of the friction mass block assembly and the secondary mass block, respectively.

[0028] , The initial radius is where the friction mass block assembly and the secondary mass block are located.

[0029] An aircraft comprising the aforementioned adaptive torsional damper.

[0030] Beneficial effects: The adaptive torsional vibration damper consists of a central ring, an inner friction ring, a secondary mass block, a friction mass block assembly, a secondary spring, a primary spring, and a ball bearing. It is installed on the shaft system of variable-speed helicopter rotors, torque transmission paths, and transmission systems to suppress torsional vibration loads that change with rotational speed and during variable-speed processes. It also has the function of absorbing vibration loads in the plane perpendicular to the axis. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an adaptive torsional vibration damper;

[0032] Figure 2 This is an isometric drawing of an adaptive torsional damper;

[0033] Figure 3 This is a cross-sectional view of the adaptive torsional damper along the central plane of the inner friction ring;

[0034] Figure 4 This is a cross-sectional view of the adaptive torsional damper from plane AA.

[0035] In the diagram, 100 is the central ring, 101 is the central hole, 102 is the centrifugal groove, 103 is the outer groove, 200 is the inner friction ring, 300 is the secondary mass block, 400 is the friction mass block assembly, 401 is the friction plate, 402 is the slide frame, 500 is the secondary spring, 600 is the primary spring, 700 is the ball bearing, 701 is the outer ring, 702 is the ball, and 703 is the inner ring. Detailed Implementation

[0036] A speed-adaptive torsional vibration damper mounted on a shaft system such as a rotor hub or transmission system. It mainly consists of a central ring, an inner friction ring, a secondary mass block, a friction mass block assembly, a secondary spring, a primary spring, and ball bearings. The ball bearings can also be implemented using planar bearings such as roller bearings.

[0037] The central ring has a centrifugal groove, a central hole, and an outer groove. Inside the centrifugal groove, from the central hole to the outer groove, are sequentially installed a secondary spring, a secondary mass block, a primary spring, and a friction mass block assembly. The secondary mass block moves radially within the centrifugal groove under the action of centrifugal force. The friction mass block assembly can move within the groove along the radius of the central ring.

[0038] A ball bearing is installed in the outer groove of the central ring, and the inner ring of the ball bearing is connected to the outer groove of the central ring. The outer ring of the ball bearing is connected to the inner friction ring, allowing the inner friction ring to rotate around the central ring.

[0039] The inner surface of the inner friction ring is made of wear-resistant materials, such as high manganese steel, wear-resistant high chromium cast iron, wear-resistant alloy steel, etc. When the central ring and the inner friction ring rotate relative to each other, the wear-resistant surface of the inner friction ring will move relative to the friction mass block assembly to generate sliding friction force.

[0040] The friction mass assembly consists of a friction plate and a sliding frame; the friction plate is made of powder metallurgy material. The friction plate is bonded to the outer surface of the sliding frame along the radial direction. The sliding frame is connected to a primary spring, which is initially in a compressed state. The outer surface of the friction plate is in contact with the wear-resistant surface of the inner friction ring.

[0041] The adaptive torsional damper is connected to the rotating component through the central hole of the central ring and is fixed to the rotating component, and can rotate together with the rotating component.

[0042] The key points of this invention are:

[0043] Traditional torsional vibration damping systems or helicopter rotor hub vibration absorption systems are designed for a specific rotational frequency. Their optimal isolation frequency is singular and they cannot simultaneously meet the vibration damping requirements in both the torsional direction and the in-plane. This invention presents an adaptive torsional vibration damper device that simultaneously possesses vibration damping capabilities in both the rotational plane and the torsional direction. A planar spring oscillator system, composed of a primary spring, a secondary spring, and a secondary mass block, can reduce the vibration response in the rotor's rotational plane. A torsional friction system, consisting of a friction mass block assembly and an inner friction ring, can effectively reduce torsional vibrations caused by changes in rotational speed during variable speed operations. Due to centrifugal force, the centrifugal force of the spring oscillator system varies at different rotational speeds, resulting in different normal pressures on the contact surfaces of the friction mass block assembly and the inner friction ring. This adapts to the vibration damping requirements at different rotational speeds, ensuring vibration damping needs for variable-speed rotor helicopters throughout their full flight envelope.

[0044] One characteristic of the adaptive torsional vibration damper is that it consists of a planar vibration damping system composed of a primary spring, a secondary spring, and a secondary mass block. This design allows the invention to function similarly to a spring oscillator vibration absorption system in a plane, reducing the vibration signal within the rotor shaft system. Simultaneously, due to the relative friction between the friction mass block assembly and the inner friction ring, a certain amount of frictional damping is provided during the vibration absorption system's movement, increasing the dissipation of vibration energy. Furthermore, with a fixed initial pressure between the friction mass block assembly and the inner friction ring, the contact pressure between the friction mass block assembly and the inner friction ring increases with the magnitude of the planar excitation vibration, resulting in greater equivalent frictional damping and stronger vibration absorption capacity. This allows it to better adapt to changes in planar vibration excitation, ensuring that the vibration of the rotor shaft system within the plane remains at a low level.

[0045] Another characteristic of the adaptive torsional vibration damper is that it comprises a torsional damping system consisting of a spring system, a friction mass assembly, a central ring, a ball bearing, and an inner friction ring. This design enables the invention to reduce torsional vibration caused by changes in torsional acceleration in the torsional direction. When the rotational speed of the mounting shaft changes, the rotational speed will accelerate or decelerate, causing relative movement between the central ring and the inner friction ring. This movement will also cause relative displacement between the inner friction ring and the friction mass assembly, thereby providing frictional damping in this direction, absorbing the torsional vibration caused by changes in rotational speed in the torsional direction, and improving stability in the torsional direction.

[0046] The working principle of this invention is as follows:

[0047] When the shaft system of a variable-speed helicopter rotor, torque transmission path, or drive system experiences plane vibration perpendicular to the axis, an adaptive torsional damper mounted on the shaft system...

[0048] Assuming the mass of the spring and other damping of the system are negligible, the friction surfaces of the friction plates are tightly fitted, and the wear state of the friction plates is not considered, then there are the following four states.

[0049] State 1, stationary state

[0050] Since the spring is in a pre-compressed state, there is a pressure between the friction plate and the inner friction ring:

[0051] State 2: The shaft system rotates at a constant speed.

[0052] Assume that the rotational speed of the shaft system at this time is Assume the internal friction ring is subjected to an external damping force of... At this point, there are two possible scenarios:

[0053] 2.1 There is no relative motion between the central ring and the inner friction ring.

[0054] That is

[0055] At this time there is The centrifugal force it experiences is

[0056]

[0057] 2.2 The central ring and the inner friction ring undergo relative motion.

[0058] At this time there is , The centrifugal forces they experience are respectively

[0059]

[0060]

[0061] At this moment, the friction plate is subjected to pressure changes and sliding friction force.

[0062]

[0063]

[0064] State 3, Shaft system acceleration / deceleration rotation

[0065] At this point, the increase in frictional force required for the inner friction ring to remain relatively stationary with respect to the central ring is:

[0066]

[0067] 3.1 There is no relative motion between the central ring and the inner friction ring.

[0068] That is

[0069] At this time there is The centrifugal force it experiences is

[0070]

[0071] 3.2 The central ring and the inner friction ring undergo relative motion.

[0072] At this time there is , The centrifugal forces they experience are respectively

[0073]

[0074]

[0075] At this moment, the friction plate is subjected to pressure changes and sliding friction force.

[0076]

[0077]

[0078] Solving the above equations yields the centrifugal force and frictional force acting on each mass under different rotational states around the central axis.

[0079] State 4: Vibration in a plane perpendicular to the axis

[0080] When the adaptive torsional damper is arranged symmetrically, then:

[0081]

[0082] And at this time, the vibration absorption frequency of the vibration absorption system is

[0083]

[0084] In summary:

[0085] To achieve the highest efficiency of the vibration damper, theoretically, the maximum static friction is reached at the rated rotational speed. At this point, the vibration damper provides the best damping effect for shaft acceleration and deceleration. That is:

[0086]

[0087] For the vibration reduction requirements of the rotor system in the rotating plane, the vibration reduction requirement in the rotating coordinate system is then... Then the secondary mass block of the torsional damper is:

[0088]

[0089] To achieve coordinated spring movement, the spring stiffness must be the same, resulting in the following design parameters:

[0090]

[0091] , The initial pressure and its change between the friction plate and the inner friction ring.

[0092] , The rotational speed and the change in rotational speed of the shaft system at a constant speed.

[0093] The moment of inertia of the internal friction ring

[0094] Acceleration and deceleration of shaft rotation angle

[0095] The internal friction ring is subjected to external damping force.

[0096] The frictional force between the friction plate and the inner friction ring

[0097] The maximum static friction force between the friction plate and the inner friction ring.

[0098] , The masses of the friction mass block assembly and the secondary mass block are respectively...

[0099] , Centrifugal force of the friction mass block assembly and the secondary mass block, respectively.

[0100] External load for planar vibration perpendicular to the axis

[0101] , The initial radius of the friction mass block assembly and the secondary mass block.

[0102] The displacement of the secondary mass block under centrifugal force

[0103] , The stiffness of the primary and secondary springs, respectively.

[0104] The absorption frequency of the planar motion vibration absorption system

[0105] The coefficient of friction between the friction plate and the inner friction ring.

[0106] , The linear velocities of the friction mass assembly and the secondary mass about the center are respectively.

[0107] The radius of the position of the secondary mass block during its rotation

[0108] The increase in frictional force required for the inner friction ring to remain stationary relative to the central ring

[0109] Pi

[0110] The advantages of this invention are:

[0111] The adaptive torsional vibration damper can provide different magnitudes of frictional damping force according to changes in shaft rotation speed to adapt to the vibration reduction requirements of variable speed shaft systems: First, the torsional vibration damping system, composed of a central ring, inner friction ring, and friction mass block assembly, can reduce the excitation of vibration in the torsional direction and vibration caused by acceleration and deceleration. At the same time, due to the centrifugal effect of the spring system containing the secondary mass block, it can adapt to the frictional damping force requirements under different rotational speeds and rates of change of rotational speed. Second, the spring oscillator system, composed of the secondary mass block and spring, can not only meet the requirements of the friction plate for changes in normal pressure at different rotational speeds, but also absorb the vibration of the shaft system in the planar direction. Third, the preload spring can provide the elastic deformation requirements of the mass spring system during vibration absorption, and can also ensure that the friction plate is always under pressure. Moreover, when the rotational speed changes, the equilibrium position of the secondary mass block changes under the action of centrifugal force.

Claims

1. An adaptive torsional vibration damper, characterized in that: The vibration damper includes: a central ring, a primary spring, a secondary spring, a secondary mass block, a friction mass block assembly, and an inner friction ring; The central ring includes: an outer ring, a concentric inner ring with a central hole, and N sets of centrifugal grooves; the inner wall of the outer ring is connected to the outer wall of the inner ring with the central hole through the N sets of centrifugal grooves; the central ring is mounted on the rotating component through the inner ring with the central hole and rotates together with the rotating component; N is a natural number greater than or equal to 2; The primary spring, secondary spring, secondary mass block, and friction mass block assembly each consist of N sets, which are respectively arranged in N sets of centrifugal tanks; one end of the secondary spring is connected to the outer wall of the inner ring of the central hole, and the other end is connected to the inner side of the mass block, the outer side of the mass block is connected to one end of the primary spring, and the other end of the primary spring is connected to the friction mass block assembly. The outer ring has an annular groove that runs through the inner and outer end faces of the outer ring. The inner friction ring is disposed in the annular groove and is connected to the outer ring through a sliding unit and rotates along the annular groove in a sliding manner.

2. The vibration damper according to claim 1, characterized in that: The centrifuge tank is equipped with a slide rail, and the secondary mass block moves radially along the slide rail under the action of centrifugal force.

3. The vibration damper according to claim 2, characterized in that: N groups of centrifuge tanks are evenly distributed circumferentially.

4. The vibration damper according to claim 3, characterized in that: N is 4.

5. The vibration damper according to claim 4, characterized in that: The sliding unit is a ball bearing.

6. The vibration damper according to claim 5, characterized in that: The inner surface of the inner friction ring is made of wear-resistant material to form a wear-resistant surface. The primary spring is always in a compressed state, pressing the friction mass block assembly onto the inner friction ring, and the friction mass block assembly and the inner friction ring are in frictional contact.

7. The vibration damper according to claim 6, characterized in that: The friction mass block assembly includes a friction plate and a sliding frame; the sliding frame is connected to a primary spring, the friction plate is connected to the outside of the sliding frame, and the friction plate is in frictional contact with the inner friction ring.

8. The vibration damper according to claim 7, characterized in that: The formulas for calculating the stiffness k1 of the primary spring, the stiffness k2 of the secondary spring, and the mass m of the secondary mass block are as follows: This represents the initial pressure between the friction plate and the inner friction ring. The rotational speed at which the rotating part rotates at a constant speed; Let be the moment of inertia of the internal friction ring; The rotational angular acceleration of the rotating component; The internal friction ring is subjected to external damping force; This refers to the frictional force between the friction plate and the inner friction ring. This is the maximum static friction force between the friction plate and the inner friction ring; , These refer to the masses of the friction mass block assembly and the secondary mass block, respectively. , The initial radius is where the friction mass block assembly and the secondary mass block are located.

9. An aircraft, characterized in that: The aircraft includes the adaptive torsional damper as described in any one of claims 1-8.

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