A transmission shaft support structure of an aero-engine transmission system test bench

Abstract

The present application relates to the technical field of aero-engine transmission system test equipment, and particularly relates to a transmission shaft support structure of an aero-engine transmission system test bench, which comprises a shell, a transmission shaft and left and right bearings installed at two ends of the shell. An oil supply ring is installed in the shell and the end faces of the two ends of the oil supply ring are respectively arranged in a spaced manner with the end faces of the outer rings of the left and right bearings. The transmission shaft is provided with a first annular table and a second annular table, the left end face of the first annular table abuts against the right end face of the inner ring of the left bearing, and the right end face of the second annular table abuts against the left end face of the inner ring of the right bearing, so as to limit the inner rings of the bearings from the inside. Wave springs and gap rings are arranged between the left and right end covers and the outer rings of the bearings, and the elastic pre-tightening force is applied from the outside to the inside, so as to form an elastic positioning system with inside and outside cooperation to absorb vibration and thermal expansion. A gasket ring and a wind shield ring are installed between the flange plate and the end cover, so as to form an air gap cavity with a specific gap to inhibit the loss of lubricating oil caused by high-speed negative pressure.

Description

Technical Field

[0001] This invention relates to the field of test equipment for aero-engine transmission systems, and in particular to a transmission shaft support structure for an aero-engine transmission system test bench. Background Technology

[0002] The aero-engine transmission system test bench is an indispensable key piece of equipment in the research and development and finalization process of aero-engines. Its function is to accurately simulate the engine's operating conditions under various flight conditions, thereby conducting comprehensive and rigorous testing and verification of the transmission system's power transmission efficiency, lubrication performance, vibration characteristics, durability, and reliability. As the core rotating component connecting the drive end and load end of the test bench, the stability of the drive shaft's operation directly determines the testing accuracy and data validity of the entire test bench system. Therefore, providing a reliable and precise support structure for the drive shaft is of paramount importance in the design of the test bench.

[0003] However, with the pursuit of high thrust-to-weight ratio and high efficiency in modern aero engines, their transmission systems are developing towards ultra-high speed and high power density. For example, the input speed of the accessory transmission system in some advanced aero engines has exceeded 20,000 rpm, and the transmitted power can reach hundreds or even thousands of kilowatts. Under such extreme conditions, traditional driveshaft support structures have exposed many technical problems: First, traditional support structures lack sufficient axial positioning and elastic buffering capabilities. In traditional structures, the axial positioning of bearings often relies on the rigid clamping of the end caps, and the shoulder positioning of the drive shaft itself is relatively simple. This fails to provide precise, reliable, and adaptive positioning for the bearings and drive shaft under conditions of ultra-high-speed operation and wide temperature variations. When thermal expansion or bearing wear occurs, this rigid positioning structure either generates excessive thermal stress, leading to bearing jamming, or produces harmful axial runout clearance, causing impact and vibration.

[0004] Secondly, there is the problem of lubricating oil leakage caused by "pump suction negative pressure" in high-speed rotating components. At ultra-high speeds, large-diameter rotating components such as flanges connected to the drive shaft have extremely high outer edge linear velocities. This creates a strong circumferential shear airflow within the narrow annular gap between the component and the stationary end cover, generating a significant centrifugal pump suction effect and forming a localized negative pressure zone. This negative pressure continuously draws out the precious lubricating oil used to lubricate the bearings from inside the housing, resulting in excessively rapid oil consumption and severe consequences such as bearing burnout due to insufficient oil. Traditional single-contact seals or simple gap seals are unlikely to fundamentally suppress this flow-driven leakage mechanism.

[0005] Third, the directional and precise lubrication and cooling efficiency of the bearings is insufficient. During operation, ultra-high-speed bearings generate extremely high frictional heat between the rolling elements and raceways, while oil churning losses also increase dramatically. If the oil supply method is not appropriate, the lubricating oil cannot penetrate the high-speed air curtain around the bearing and be accurately delivered to the rolling contact area, resulting in the inability to establish an stable elastohydrodynamic (EHL) oil film, causing the bearing temperature to rise rapidly and its lifespan to be significantly shortened.

[0006] Therefore, in view of the above-mentioned shortcomings of the existing technology, it is urgent to develop a new type of transmission shaft support structure that can not only provide reliable axial elastic positioning and adaptive buffering, but also effectively suppress high-speed negative pressure leakage from the structural design, and achieve precise and efficient bearing lubrication and cooling. Summary of the Invention

[0007] The main objective of this invention is to propose a transmission shaft support structure for an aero-engine transmission system test bench, aiming to solve at least one of the above-mentioned technical problems.

[0008] To achieve the above objectives, this invention proposes a drive shaft support structure for an aero-engine transmission system test bench, comprising a housing, a drive shaft, a left bearing, and a right bearing. The left and right bearings are mounted at both ends of the transverse through-hole of the housing and sleeved on both ends of the drive shaft, forming a two-point support rotation system for the drive shaft.

[0009] Inside the transverse through-hole of the housing, in the area between the left and right bearings, an oil supply ring is installed. This oil supply ring has a central through-hole through which the drive shaft passes, maintaining an annular gap between them. The inner wall of the oil supply ring does not contact the outer cylindrical surface of the drive shaft, allowing the drive shaft to rotate freely. The installation of the oil supply ring inside the housing has a significant structural feature: the left end face of the oil supply ring is not tightly abutted against the right end face of the left bearing outer ring, but rather spaced apart, meaning there is a pre-designed axial gap between them. Similarly, the right end face of the oil supply ring is also spaced apart from the left end face of the right bearing outer ring, also with an axial gap. This spaced-out design means that the oil supply ring does not directly contact or constrain the outer rings of the left and right bearings axially, allowing the bearing outer rings a certain degree of freedom in the axial direction.

[0010] Corresponding to the free state of the outer ring of the bearing, the inner ring of the bearing is precisely axially limited by an annular platform on the drive shaft. Specifically, a first annular platform is integrally formed on the outer cylindrical surface of the drive shaft body, located on the right side of the left bearing mounting journal. The left end face of the first annular platform is a precision-machined locating surface that is strictly perpendicular to the axis of the drive shaft. This left end face precisely abuts against the right end face of the left bearing inner ring, forming a blocking limit. Thus, the axial displacement of the left bearing inner ring to the right is stopped by the first annular platform. Symmetrically, a second annular platform is integrally formed on the left side of the right bearing mounting journal of the drive shaft. The right end face of the second annular platform is also a precision locating surface. This right end face precisely abuts against the left end face of the right bearing inner ring, forming a blocking limit. Thus, the axial displacement of the right bearing inner ring to the left is stopped by the second annular platform. In this way, the inner rings of both the left and right bearings are reliably axially limited by the annular platforms on the drive shaft.

[0011] To achieve elastic preload and axial clearance control for the entire bearing system, the support structure of this invention incorporates a combination of wave springs and clearance rings at both ends of the housing. A left end cap is bolted to the left end of the housing. From left to right, a first wave spring and a first clearance ring are sequentially arranged between the right end face of the left end cap and the left end face of the outer ring of the left bearing. After assembly, the right end face of the first clearance ring is tightly against the left end face of the outer ring of the left bearing; while a small axial clearance is maintained between the left end face of the first clearance ring and the right end face of the left end cap. The two ends of the first wave spring abut against the right end face of the left end cap and the first clearance ring, respectively. When the left end cap is tightened, it transmits a rightward axial preload force to the outer ring of the left bearing through the first wave spring and the first clearance ring. Symmetrically, a right end cap is bolted to the right end of the housing. Between the left side of the right end cover and the right end face of the right bearing outer ring, a second wave spring and a second clearance ring are sequentially arranged from right to left. After assembly, the left end face of the second clearance ring is tightly against the right end face of the right bearing outer ring; while a small axial clearance is maintained between the right end face of the second clearance ring and the left end face of the right end cover. The two ends of the second wave spring abut against the left end face of the right end cover and the second clearance ring, respectively. When the right end cover is tightened, it transmits a leftward axial preload force to the outer ring of the right bearing through the second wave spring and the second clearance ring.

[0012] Because the oil supply ring and the outer rings of the left and right bearings are spaced apart, creating an axial clearance, the axial preload applied by the left end cover acts entirely on the outer ring of the left bearing via the first wave spring and the first clearance ring, pushing it from the outside inward (to the right). Similarly, the axial preload applied by the right end cover acts entirely on the outer ring of the right bearing via the second wave spring and the second clearance ring, pushing it from the outside inward (to the left). In this way, the outer rings of both the left and right bearings are elastically preloaded from both ends towards the center. Specifically, when the left end cover pushes the outer ring of the left bearing to the right, the force is transmitted through the rolling elements of the left bearing to the inner ring of the left bearing, and then to the left end face of the first annular platform, pushing the entire transmission shaft to the right. Simultaneously, the right end cover pushes the outer ring of the right bearing to the left, the force is transmitted through the rolling elements of the right bearing to the inner ring of the right bearing, and then to the right end face of the second annular platform, pushing the entire transmission shaft to the left. The two sets of equal and opposite elastic preload forces achieve balance on the transmission shaft, realizing high-precision axial elastic positioning of the entire transmission shaft system.

[0013] This structural design has significant technical advantages: First, the spacing between the oil supply ring and the outer ring of the bearing ensures that the oil supply ring is merely a functional element for oil supply and does not participate in the axial force chain of the bearing, thus avoiding potential deformation or positioning deviation caused by the oil supply ring bearing axial force. Second, the axial preload provided by the first and second wave springs is elastically variable. When the drive shaft rotates at high speed and the system temperature rises, causing thermal expansion and axial deformation, the wave springs can be further compressed to absorb thermal deformation, preventing the bearing from bearing excessive rigid thermal stress and seizing. When the bearing experiences minor wear due to long-term operation, leading to increased clearance, the elastic energy stored in the wave springs is released to automatically compensate for the clearance, maintaining the optimal preload between the bearing rolling elements and raceways, thereby suppressing vibration and extending bearing fatigue life. Third, the first and second annular platforms respectively limit the inner rings of the left and right bearings from the inside, forming a coordinated "clamping" elastic positioning with the outer wave spring preload system, ensuring that the drive shaft neither experiences harmful axial movement nor seizing due to axial deformation caused by thermal expansion.

[0014] Furthermore, to effectively solve the problem of negative pressure oil suction under ultra-high-speed operating conditions, this invention designs a unique air gap anti-leakage structure at the output flanges at both ends of the drive shaft. A first flange is installed at the left end of the drive shaft. On the left end face of the left end cover, a first gasket and a first windshield ring are coaxially installed from right to left. The outer cylindrical surface of the right end of the first flange, together with the first windshield ring, the first gasket, and the left end cover, form a first air gap cavity. Symmetrically, a second flange is installed at the right end of the drive shaft; on the right end face of the right end cover, a second gasket and a second windshield ring are installed from left to right; the outer cylindrical surface of the left end of the second flange, together with the second windshield ring, the second gasket, and the right end cover, form a second air gap cavity.

[0015] When the drive shaft drives the first and second flanges to rotate at high speed, the areas where negative pressure is most likely to be generated are the junction of the outer cylindrical surface of the right end of the first flange and the center hole of the left end cover, and the junction of the outer cylindrical surface of the left end of the second flange and the center hole of the right end cover. In this invention, the first air gap cavity forms a barrier, isolating the circumferential rotating airflow driven by the high-speed rotation of the first flange and preventing the lubricating oil at the left bearing position from being lost due to negative pressure. Similarly, the second air gap cavity also forms a barrier, isolating the circumferential rotating airflow driven by the high-speed rotation of the second flange and preventing the lubricating oil at the right bearing position from being lost due to negative pressure. This non-contact air gap cavity structure acts as a "pressure equalization cavity" and a "turbulent dissipation cavity" in the sense of fluid dynamics, effectively disrupting the formation conditions of a continuous negative pressure zone, significantly suppressing the abnormal loss of lubricating oil from the inside of the housing to the outside due to the pumping effect, thereby ensuring that the bearing is always in a good oil-immersed lubrication environment.

[0016] As a preferred connection method, the connection between the first and second flanges and the drive shaft can employ a spline fit capable of transmitting high torque. Specifically, internal spline sleeves are machined on the right end of the first flange and the left end of the second flange, while external spline heads are correspondingly machined on both ends of the drive shaft. The drive shaft inserts into the spline sleeves of the two flanges through the external spline heads at both ends, forming a spline fit to transmit a large driving torque. Pressure caps are also installed on the end faces of the drive shaft at both ends using screws, firmly pressing the first and second flanges axially onto the shoulders of the drive shaft to prevent axial movement of the flanges.

[0017] Regarding the critical dimensional control of the air gap anti-leakage structure, this invention further specifies that: the single-sided gap between the inner surface of the first baffle ring and the outer cylindrical surface of the right end of the first flange is 0.5 to 1 mm; the single-sided gap between the inner surface of the second baffle ring and the outer cylindrical surface of the left end of the second flange is also 0.5 to 1 mm. This gap range is one of the core design parameters of this invention: if the gap is too large, it will be unable to effectively disrupt and throttle the rotating airflow, resulting in a poor anti-leakage effect; if the gap is too small, there is a risk of scraping or even seizing with the flange when the parts undergo slight thermal deformation or centrifugal expansion due to high speed and high temperature rise. The gap range of 0.5 to 1 mm is the optimal range obtained after extensive fluid simulation analysis and experimental verification, which can achieve the best negative pressure suppression effect while ensuring absolute safe operation.

[0018] To further enhance the sealing effect and achieve effective isolation from external contaminants and reliable sealing of internal oil and gas, this invention also incorporates a dynamic contact seal. A first sealing ring is installed in the stepped inner hole of the left end cover, with its lip tightly abutting the outer cylindrical surface of the right end of the first flange, forming a dynamic contact rotary shaft seal. Symmetrically, a second sealing ring is also installed in the stepped inner hole of the right end cover, with its lip tightly abutting the outer cylindrical surface of the left end of the second flange, forming a dynamic contact rotary shaft seal.

[0019] To address the stringent requirements of directional forced lubrication in ultra-high-speed bearings, this invention highly integrates the oil supply function onto the oil supply ring. Specifically, an annular groove is formed on the outer cylindrical surface of the oil supply ring. When the oil supply ring is inserted into the transverse through-hole of the housing, the annular groove and the smooth inner wall of the housing form a sealed annular oil cavity, serving as a storage and distribution chamber for lubricating oil. An inwardly tapering first oil injection ring is integrally machined onto the inner wall of the left end of the oil supply ring. Multiple small first oil injection holes are uniformly machined along the circumference on the left end face of the first oil injection ring. The rear ends of all these oil injection holes communicate with the annular oil cavity, and their front outlets precisely point towards the assembly area of ​​the left bearing ball and cage. Symmetrically, an integrally formed second oil injection ring and multiple second oil injection holes are provided on the right end of the oil supply ring, with their outlets precisely pointing towards the assembly area of ​​the right bearing ball and cage. An oil inlet is provided at a corresponding position on the casing. The oil inlet is directly connected to the annular oil cavity and is sealed by a first oil inlet plug. Alternatively, the first oil inlet plug can be removed and the oil inlet can be connected to an external oil pipe.

[0020] During operation, pressurized lubricating oil from the external lubrication system fills the annular oil chamber through the injection port. The annular oil chamber stabilizes and distributes the pressure, ensuring that the outlet pressure and flow rate of each injection hole are essentially consistent. Subsequently, driven by pressure, the lubricating oil is accelerated through the throttling of the first and second injection holes, forming multiple high-speed, directional lubricating oil jets. These jets possess extremely high kinetic energy, sufficient to penetrate the boundary air curtain formed around the bearing during high-speed rotation, and are precisely and directly sprayed onto the contact area between the rolling elements and the inner and outer raceways, thereby reliably establishing an elastohydrodynamic lubricating oil film. Simultaneously, the high-flow-rate lubricating oil jets also enable efficient forced convection heat transfer within the bearing, rapidly removing frictional heat and churning heat, strictly controlling the bearing operating temperature within safe limits.

[0021] To ensure the sealing of the annular oil cavity and prevent lubricating oil leakage from the mating surface between the oil supply ring and the housing, sealing ring mounting grooves are provided on the outer cylindrical surfaces at both ends of the oil supply ring, and O-rings are installed in the grooves. These two O-rings are compressed between the outer wall of the oil supply ring and the inner wall of the housing, forming a reliable static seal, ensuring that all pressurized lubricating oil can only be sprayed onto the bearing through the oil injection hole and will not leak from the mating clearance.

[0022] To achieve real-time monitoring and fault early warning of the supporting structure's operating status, this invention organically integrates temperature and vibration sensors into the housing. A vibration sensor base is installed on the outer wall of the housing for mounting a vibration acceleration sensor to pick up vibration signals in real time. Simultaneously, a temperature sensor mounting hole is provided on the housing, corresponding to the positions directly above the left and right bearings, and a temperature sensor is installed in each hole. The temperature sensor's probe passes through the mounting hole, and its sensitive end makes direct and stable contact with the outer surface of the outer ring of the left and right bearings. Due to its proximity to the heat source and the use of direct contact temperature measurement, the temperature sensors can provide real-time feedback of the bearing's operating temperature with minimal thermal inertia and extremely high accuracy. All sensor signals are uniformly connected to the test bench's measurement and control system. Operators can monitor the bearing's health status in real time and set early warning and alarm thresholds, achieving intelligent and automated test process management and safety protection.

[0023] To balance the pressure fluctuations inside the housing caused by temperature changes and oil churning, a pressure balancing and breathing device is installed at the center of the top of the housing. A vent cap mounting cylinder is installed at this location, with its central through-hole connecting downwards to the inner cavity of the oil supply ring, allowing the internal and external pressures of the housing to be balanced through this channel. At the top of the vent cap mounting cylinder is a vent cap, the interior of which is filled with an air filter element. When the gas inside the housing expands due to increased temperature, excess gas is filtered through the air filter element and discharged into the atmosphere; when the housing cools and generates negative pressure, external air is drawn in through the filter element, effectively filtering out dust and impurities from the environment and protecting the cleanliness of the internal precision bearings and lubricating oil.

[0024] As a further optimization, this invention features a clever design for the axial positioning of the oil supply ring. A stepped mounting hole is machined at the center of the breathing channel at the top of the housing. The upper half of this mounting hole is a larger-diameter internal threaded hole for screwing in and securing the vent cap mounting sleeve; the lower half is a smaller-diameter internal threaded hole for screwing in a hexagonal cone-shaped set screw. After the hexagonal cone-shaped set screw is screwed in, its conical tip precisely abuts against the pre-machined conical positioning through-hole on the outer circumference of the oil supply ring, thus firmly locking the oil supply ring axially within the housing and preventing axial displacement under lubricating oil pressure and vibration impact. Ingeniously, a through-hole is machined at the central axis of this hexagonal cone-shaped set screw. This through-hole connects the inner cavity of the oil supply ring with the central through-hole of the vent cap mounting sleeve above, thus ensuring unobstructed air pressure balance while locking and positioning, demonstrating a sophisticated multi-functional structural design.

[0025] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows: (1) Excellent axial elastic positioning and self-compensation capability: The first annular platform on the drive shaft axially limits the inner ring of the left bearing from the inside (right side), and the second annular platform axially limits the inner ring of the right bearing from the inside (left side). Combined with the wave springs and clearance rings inside the end caps, elastic preload is applied to the outer rings of the left and right bearings from the outside, forming an elastic positioning system of "internal and external coordinated clamping". The spacing between the oil supply ring and the outer ring of the bearing ensures that the oil supply ring is only a function element for oil supply and does not participate in the axial force chain of the bearing, thus avoiding the risk of deformation or positioning deviation due to axial force. The elastic preload provided by the wave springs allows the bearing system to adapt to the thermal expansion and contraction of the drive shaft and the slight wear during long-term operation, always maintaining the optimal preload working state. This completely eliminates the risk of thermal stress jamming caused by rigid preload or the vibration and impact problems caused by clearance, significantly extending the service life of the ultra-high speed bearing.

[0026] (2) Highly efficient negative pressure suppression and reliable sealing performance: A unique air gap cavity structure consisting of a windproof ring and a gasket ring is constructed between the high-speed rotating flange and the stationary end cover, which greatly suppresses the external loss of lubricating oil caused by high-speed rotation.

[0027] (3) Precise and efficient bearing directional lubrication and cooling: The integrated design of the oil supply ring combines the functions of the oil passage, oil reservoir, and oil nozzle into one, realizing precise forced spray lubrication of the left and right bearing ball contact areas. Multiple high-speed oil jets can effectively break through the airflow barrier of the high-speed rotation of the bearing, ensuring that the lubricating oil reaches the area that needs cooling and lubrication the most, which greatly reduces the operating temperature of the bearing. This is the fundamental guarantee for extending the bearing life.

[0028] (3) The vibration and temperature sensors integrated on the housing, as well as the dual functions (positioning and breathing) achieved by the integrated vent cap and the internal hexagonal cone set screw on the top, embody a high level of integrated design concept, reduce the number of parts, and improve the compactness and reliability of the structure. At the same time, the modular end caps, flange connections, and detachable left and right end caps make the inspection and replacement of vulnerable parts such as bearings and seals very convenient. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1This is a three-dimensional structural diagram of the transmission shaft support structure of an aero-engine transmission system test bench provided by the present invention.

[0031] Figure 2 This is a front view of the drive shaft support structure of an aero-engine transmission system test bench provided by the present invention.

[0032] Figure 3 for Figure 2 Sectional view of AA.

[0033] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0034] Figure 5 for Figure 3 Enlarged view of point B in the middle.

[0035] Reference numerals: 1. Drive shaft; 1a. First annular platform; 1b. Second annular platform; 2. Housing; 2a. Oil inlet; 2b. Mounting hole; 2c. Mounting plate; 3. Oil supply ring; 3a. First oil injection ring; 3b. Second oil injection ring; 3c. First oil injection hole; 3d. Second oil injection hole; 4. Left end cover; 5. Right end cover; 6a. First flange; 6b. Second flange; 7. Pressure cap; 8. Vent cap mounting sleeve; 9. Hexagonal cone end set screw; 10a. First windshield ring; 10b. Second windshield ring; 11a. First washer; 11b. Second washer; 12. Vibration sensor base; 13a. First clearance ring; 13b. Second clearance ring; 14. Screw 15a, First sealing ring; 15b, Second sealing ring; 16a, First wave spring; 16b, Second wave spring; 17a, Left bearing; 17b, Right bearing; 18, Temperature sensor; 19, Vent cap; 20, O-ring; 21, First screw; 22, Third screw; 23, Fourth screw; 24, Fifth screw; 25, Second screw; 26, Self-locking nut; 27, Wire thread insert; 28, First locking washer; 29, Second locking washer; 30, Combined sealing washer; 31, First oil port plug; 32, Second oil port plug; 33, Third locking washer; 34a, First air gap cavity; 34b, Second air gap cavity; 35, Annular oil cavity. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0038] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0039] This embodiment details a drive shaft support structure for an aero-engine transmission system test bench, which mainly includes a housing 2, a drive shaft 1, a left bearing 17a, a right bearing 17b, and an oil supply ring 3.

[0040] The main body of the supporting structure is the housing 2. The housing 2 has a transverse through-hole inside, which is used to accommodate internal components such as bearings and oil supply rings. A base is welded to the bottom of the housing 2, and the base has a structure with multiple reinforcing ribs to improve its overall bending and torsional stiffness. The bottom of the base has a mounting plate 2d for a secure connection with the test bench.

[0041] The drive shaft 1 is the main body that rotates at high speed. A left journal is provided at the left end of the drive shaft 1 for mounting the left bearing 17a. A first annular platform 1a is integrally machined at the right side of the left journal. The first annular platform 1a has a precision-machined (e.g., precision-turned) left end face that is strictly perpendicular to the axis of the drive shaft 1. This left end face abuts against the right end face of the inner ring of the left bearing 17a, thereby limiting the axial displacement of the inner ring of the left bearing 17a inward (to the right). A right journal is provided at the right end of the drive shaft 1 for mounting the right bearing 17b. A second annular platform 1b is integrally machined at the left side of the right journal. The second annular platform 1b has a precision-machined right end face that is strictly perpendicular to the axis of the drive shaft 1. This right end face abuts against the left end face of the inner ring of the right bearing 17b, thereby limiting the axial displacement of the inner ring of the right bearing 17b inward (to the left).

[0042] In this embodiment, both the left bearing 17a and the right bearing 17b are angular contact ball bearings capable of withstanding combined loads. The left bearing 17a is installed into the transverse through-hole from the left end of the housing 2, with its inner ring fitted onto the left journal of the drive shaft 1 until the right end face of the inner ring firmly abuts against the left end face of the first annular platform 1a. The right bearing 17b is installed from the right end of the housing 2, with its inner ring fitted onto the right journal of the drive shaft 1 until the left end face of the inner ring firmly abuts against the right end face of the second annular platform 1b. Through the axial stops of these two annular platforms, the axial positions of the inner rings of the left and right bearings on the drive shaft 1 are precisely defined.

[0043] Between the two bearings, the oil supply ring 3 is precisely installed into the central area of ​​the transverse through-hole of the housing 2. The oil supply ring 3 has a central through-hole through which the drive shaft 1 passes freely, maintaining an annular gap between them and not in contact. The installation feature of the oil supply ring 3 within the housing 2 is that its axial dimension is smaller than the distance between the right end face of the outer ring of the left bearing 17a and the left end face of the outer ring of the right bearing 17b. Therefore, after assembly, the left end face of the oil supply ring 3 and the right end face of the outer ring of the left bearing 17a are not in contact, but are spaced apart, with a pre-designed axial gap of 0.2 to 0.5 mm. Similarly, the right end face of the oil supply ring 3 and the left end face of the outer ring of the right bearing 17b are also spaced apart, with another axial gap of 0.2 to 0.5 mm. This structural design clarifies that the oil supply ring 3 serves only as a lubrication element and does not participate in the axial positioning or force transmission of the bearing outer rings. The axial fixation of the oil supply ring 3 itself is achieved by the internal hexagonal tapered set screw 9, which will be detailed later.

[0044] Elastic preload and vibration absorption are achieved through the following structure: Combination Figure 3 and Figure 4 As shown, a left end cover 4 is installed at the left end of the housing 2 using a first screw 21 and a second retaining washer 29. A first wave spring 16a and a first gap ring 13a are sequentially arranged between the right end face of the left end cover 4 and the left end face of the outer ring of the left bearing 17a. The right end face of the first gap ring 13a is in close contact with the left end face of the outer ring of the left bearing 17a, and a precise annular gap is designed between its left end face and the right end face of the left end cover 4. Specifically, combined with... Figure 4As shown, the left end cover 4 has a plug-in portion and a flange plate. The plug-in portion of the left end cover 4 is used to insert into the stepped hole at the left end of the housing 2. The distance between the right end face of the flange plate of the left end cover 4 and the right end face of the plug-in portion is B2, and the distance between the right end face of the flange plate of the left end cover 4 and the left end face of the first gap ring 13a is B1, where B1 > B2. In this embodiment, B1 - B2 = 0.1 mm. An annular countersunk is provided on the left end face of the first gap ring 13a for mounting the first wave spring 16a, and the left end face of the first wave spring 16a abuts against the right end face of the left end cover 4. After the left end cover 4 is fastened to the housing 2 by the first screw 21, the elastic restoring force of the first wave spring 16a pushes the outer ring of the left bearing 17a to the right and inward through the first gap ring 13a.

[0045] Combination Figure 3 and Figure 5 As shown, a right end cover 5 is installed on the right end of the housing 2 by a second screw 25. A second wave spring 16b and a second clearance ring 13b are sequentially arranged between the left end face of the right end cover 5 and the right end face of the outer ring of the right bearing 17b. The left end face of the second clearance ring 13b is in close contact with the right end face of the outer ring of the right bearing 17b, and a precise annular gap is designed between its right end face and the left end face of the right end cover 5. Specifically, combined with... Figure 5 As shown, the right end cover 5 has a plug-in portion and a flange plate. The plug-in portion of the right end cover 5 is used to insert into the stepped hole at the outer end of the housing 2. The distance between the left end face of the flange plate of the right end cover 5 and the left end face of the plug-in portion is A2, and the distance between the left end face of the flange plate of the right end cover 5 and the right end face of the second gap ring 13b is A1, where A1 > A2. In this embodiment, A1 - A2 = 0.1 mm. An annular recess is provided on the right end face of the second gap ring 13b for mounting the second wave spring 16b, and the outer end face of the second wave spring 16b abuts against the right end face of the right end cover 5. The right end cover 5 pushes the outer ring of the right bearing 17b to the left through the second wave spring 16b and the second gap ring 13b.

[0046] The rightward preload applied by the left end cover 4 is transmitted through the rolling elements of the left bearing 17a to the inner ring of the left bearing 17a, and then to the left end face of the first annular platform 1a, pushing the entire drive shaft 1 to the right. Simultaneously, the leftward preload applied by the right end cover 5 is transmitted through the rolling elements of the right bearing 17b to the inner ring of the right bearing 17b, and then to the right end face of the second annular platform 1b, pushing the entire drive shaft 1 to the left. These two sets of equal and opposite elastic preload forces achieve balance on the drive shaft 1, precisely suspending it at an elastic support center position determined by the stiffness of the wave spring. Because there is a gap between the oil supply ring 3 and the outer ring of the bearing, this elastic preload force is not transmitted to the oil supply ring 3 at all, ensuring the structural stability of the oil supply ring 3 and the independence of its oil supply function. This elastic preload system can perfectly absorb thermal expansion and wear during operation.

[0047] To address the issue of high-speed negative pressure leakage, this embodiment incorporates a sophisticated air gap leak-proof structure. The specific structure is as follows: A first flange 6a is installed on the left end of the drive shaft 1, and a second flange 6b is installed on the right end of the drive shaft 1. Specifically, the right end of the first flange 6a and the left end of the second flange 6b are respectively configured as spline sleeves; both ends of the drive shaft 1 are respectively configured as external spline heads, used to insert into the spline sleeves of the first flange 6a and the second flange 6b to form a spline fit; pressure caps 7 are respectively installed at both ends of the drive shaft 1. Specifically, the pressure caps 7 are fastened to the ends of the drive shaft 1 by a third screw 22, a wire thread sleeve 27 and a first locking washer 28, and the pressure caps 7 are used to axially press the first flange 6a and the second flange 6b.

[0048] On the left end face of the left end cover 4, a first washer ring 11a and a first windbreak ring 10a are installed sequentially from right to left. Specifically, the first washer ring 11a and the first windbreak ring 10a are fastened to the left end face of the left end cover 4 by a fourth screw 23 and a third stop washer 33. The outer cylindrical surface of the right end of the first flange 6a, together with the first windbreak ring 10a, the first washer ring 11a, and the left end cover 4, form a first air gap cavity 34a. Furthermore, the radial clearance on one side between the inner hole of the first windbreak ring 10a and the outer cylindrical surface of the first flange 6a is strictly controlled between 0.5 and 1 mm.

[0049] Similarly, at the second flange 6b on the right end of the drive shaft 1, the second gasket 11b, the second windshield ring 10b, and the right end cover 5 together form the second air gap cavity 34b, with the single-sided gap between the windshield ring and the flange being 0.5 to 1 mm. The installation method of the second gasket 11b and the second windshield ring 10b is the same as that of the first gasket 11a and the first windshield ring 10a, and will not be described again here.

[0050] Bolts 14 and self-locking nuts 26 are respectively provided on the first flange 6a and the second flange 6b for connection to the load or to the drive shaft.

[0051] To achieve a seal, the first sealing ring 15a and the second sealing ring 15b are respectively installed in the stepped holes of the left and right end covers, providing a contact-type dynamic seal and forming the first reliable line of defense. When the flange rotates at high speed, these first air gap cavities 34a and second air gap cavities 34b form a second isolation barrier, which isolates the airflow and prevents the lubricating oil from being sucked out due to negative pressure.

[0052] In this embodiment, the oil supply lubrication system is highly integrated into the oil supply ring 3. The annular groove on the outer wall of the oil supply ring 3 forms an annular oil cavity 35 with the inner wall of the housing 2. The oil inlet 2a on the housing 2 communicates with the annular oil cavity 35 and is sealed by the first oil port plug 31. On the first oil injection ring 3a integrally formed at the left end of the oil supply ring 3, multiple first oil injection holes 3c are machined, and their outlets are directly opposite the rolling element cage area of ​​the left bearing 17a. Symmetrically, the second oil injection ring 3b and the second oil injection hole 3d at the right end are directly opposite the right bearing 17b. Therefore, the high-speed lubricating oil jets ejected from the first oil injection holes 3c and the second oil injection holes 3d can be accurately sprayed onto the balls of the target bearing. After lubrication and cooling, the lubricating oil flows back to the base at the bottom of the housing 2 through the internal clearance of the bearing and the annular clearance between the oil supply ring and the drive shaft, and is then discharged from the return port for recycling. A second oil port plug 32 is provided on the return port.

[0053] The O-rings 20 installed in the sealing grooves on the outer cylindrical surfaces at both ends of the oil supply ring 3 ensure pressure sealing at both ends of the annular oil chamber 35, preventing lubricating oil from leaking axially from the mating surface between the oil supply ring and the housing.

[0054] The vibration sensor base 12 is fixed to the housing 2 by the fifth screw 24. The vibration sensor base 12 is used to install the vibration acceleration sensor, which is used to monitor vibration. Two temperature sensors 18 are respectively installed in the mounting holes directly above the left bearing 17a and the right bearing 17b. Their temperature probes pass through the holes and directly contact the outer surface of the bearing outer ring, so as to monitor the bearing operating temperature as quickly and accurately as possible with the shortest heat conduction path and the least thermal inertia.

[0055] In the stepped mounting hole 2b at the center of the top of the housing 2, a hexagonal cone-shaped set screw 9 is screwed into the lower part. The conical tip of the set screw 9 precisely presses against the pre-machined conical positioning through hole on the outer circumference of the oil supply ring 3, thus firmly locking the oil supply ring 3 in the housing 2 axially and preventing any displacement under vibration and oil pressure. A small through hole is machined on the central axis of the hexagonal cone-shaped set screw 9. The upper part of the mounting hole 2b is screwed into the vent cap mounting cylinder 8 and sealed by a combination sealing washer 30. The top of the vent cap mounting cylinder 8 is fitted with a vent cap 19 filled with an air filter element. The central through hole of the hexagonal cone-shaped set screw 9 in the inner cavity of the oil supply ring 3, the mounting hole 2b, and the central through hole of the vent cap mounting cylinder 8 are ultimately connected to the external atmosphere through the filter inside the vent cap 19. This passage balances the internal air pressure of the housing with the external environment, while ensuring that all air entering the housing is filtered, preventing external dust contamination.

[0056] Brief description of the work process During the test, the drive shaft 1 was rotated by the drive end. The oil supply system supplied oil to the oil inlet 2a. After the lubricating oil filled the annular oil chamber 35, it was sprayed at high speed from the first oil injection hole 3c and the second oil injection hole 3d onto the ball contact area of ​​the high-speed rotating left and right bearings 17a and 17b, establishing a stable lubricating oil film and carrying away heat. As the rotational speed increased, the first and second wave springs 16a and 16b applied elastic preload from the outside to the inside, which, together with the limiting action from the inside of the first annular platform 1a and the second annular platform 1b, formed an elastic positioning system that effectively absorbed vibration and compensated for thermal expansion, maintaining the bearings in the optimal preload state at all times. The first and second air gap chambers 34a and 34b played a role in suppressing negative pressure and preventing lubricating oil from leaking out due to the pumping effect. The temperature sensor 18 and the vibration sensor monitored the bearing status in real time, and the vent cap 19 balanced the air pressure inside and outside the housing. The entire support structure operated stably and reliably at extremely high speeds, providing a solid guarantee for the testing of the aero-engine transmission system.

[0057] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A drive shaft support structure for an aero-engine transmission system test bench, comprising a housing (2), a drive shaft (1), a left bearing (17a), and a right bearing (17b); characterized in that: The left bearing (17a) and the right bearing (17b) are mounted on both ends of the transverse through hole of the housing (2) and sleeved on both ends of the drive shaft (1); An oil supply ring (3) is installed in the transverse through hole of the housing (2). The drive shaft (1) passes through the center of the oil supply ring (3), and the left end face of the oil supply ring (3) is spaced apart from the right end face of the outer ring of the left bearing (17a); the right end face of the oil supply ring (3) is spaced apart from the left end face of the outer ring of the right bearing (17b). A first annular platform (1a) and a second annular platform (1b) are provided on the transmission shaft (1); and the left end face of the first annular platform (1a) abuts against the right end face of the inner ring of the left bearing (17a), and the right end face of the second annular platform (1b) abuts against the left end face of the inner ring of the right bearing (17b). A left end cover (4) is installed at the left end of the housing (2). A first gap ring (13a) is provided between the left end cover (4) and the outer ring of the left bearing (17a). A first wave spring (16a) is provided between the first gap ring (13a) and the left end cover (4). The right end face of the first gap ring (13a) abuts against the left end face of the outer ring of the left bearing (17a), and a gap is left between the left end face of the first gap ring (13a) and the right end face of the left end cover (4). A right end cover (5) is installed at the right end of the housing (2). A second gap ring (13b) is provided between the right end cover (5) and the outer ring of the right bearing (17b), and a second wave spring (16b) is provided between the second gap ring (13b) and the right end cover (5). The left end face of the second gap ring (13b) abuts against the right end face of the outer ring of the right bearing (17b), and a gap is left between the right end face of the second gap ring (13b) and the left end face of the right end cover (5).

2. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 1, characterized in that, A first flange (6a) is installed on the left end of the drive shaft (1); a first gasket (11a) and a first windshield ring (10a) are installed from right to left on the left end face of the left end cover (4); the outer cylindrical surface of the right end of the first flange (6a) together with the first windshield ring (10a), the first gasket (11a), and the left end cover (4) form a first air gap cavity (34a). A second flange (6b) is installed on the right end of the drive shaft (1); a second gasket (11b) and a second windshield ring (10b) are installed from left to right on the right end face of the right end cover (5); a second air gap cavity (34b) is formed between the outer cylindrical surface of the left end of the second flange (6b), the second windshield ring (10b), the second gasket (11b), and the right end cover (4).

3. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 2, characterized in that, The right end of the first flange (6a) and the left end of the second flange (6b) are respectively configured as spline sleeves; the two ends of the drive shaft (1) are respectively configured as external spline heads, which are used to insert into the spline sleeves of the first flange (6a) and the second flange (6b) to form a spline fit; Pressure caps (7) are installed at both ends of the drive shaft (1) respectively, which are used to axially press the first flange (6a) and the second flange (6b).

4. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 2, characterized in that, The single-sided gap between the inner hole surface of the first windshield ring (10a) and the outer cylindrical surface of the right end of the first flange (6a) is 0.5-1mm; The single-sided gap between the inner surface of the second windshield ring (10b) and the outer cylindrical surface of the left end of the second flange (6a) is 0.5-1mm.

5. The drive shaft support structure of the aero-engine transmission system test bench according to claim 2, characterized in that, A first sealing ring (15a) is installed in the stepped inner hole of the left end cover (4). The first sealing ring (15a) is used to form a dynamic contact seal with the outer cylindrical surface of the right end of the first flange (6a). A second sealing ring (15b) is installed in the stepped inner hole of the right end cover (5). The second sealing ring (15b) is used to form a dynamic contact seal with the outer cylindrical surface of the left end of the second flange (6b).

6. The drive shaft support structure of the aero-engine transmission system test bench according to claim 1, characterized in that, An annular groove is provided on the outer cylindrical surface of the oil supply ring (3), and the annular groove and the inner wall of the housing (2) together form an annular oil cavity (35). A first oil injection ring (3a) is integrally formed on the inner wall of the left end of the oil supply ring (3). A plurality of first oil injection holes (3c) are evenly distributed in a ring on the left end face of the first oil injection ring (3a). The first oil injection holes (3c) are connected to the annular oil cavity (35), and the outlet of the first oil injection hole (3c) is aligned with the assembly area of ​​the ball and cage of the left bearing (17a). A second oil injection ring (3b) is integrally formed on the inner wall of the right end of the oil supply ring (3). A plurality of second oil injection holes (3d) are evenly distributed in a ring on the right end face of the second oil injection ring (3b). The second oil injection holes (3d) are connected to the annular oil cavity (35), and the outlet of the second oil injection hole (3d) is aligned with the assembly area of ​​the ball and cage of the right bearing (17b). An oil inlet (2a) is provided on the housing (2), and the oil inlet (2a) is connected to the annular oil cavity (35). A first oil inlet plug (31) is provided on the oil inlet (2a).

7. The drive shaft support structure of the aero-engine transmission system test bench according to claim 6, characterized in that, Sealing ring mounting grooves are provided on the outer cylindrical surfaces at both ends of the oil supply ring (3), and O-rings (20) are installed in the sealing ring mounting grooves. The two O-rings (20) are located at both ends of the annular oil cavity (35), and the O-rings (20) are used to seal with the inner wall of the housing (2).

8. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 1, characterized in that, The housing (2) is equipped with a vibration sensor for monitoring vibration parameters and a temperature sensor (18) for monitoring the temperature of the left bearing (17a) and right bearing (17b). A vibration sensor base (12) is installed on the outer wall of the housing (2) for mounting the vibration sensor; Two temperature sensor mounting holes are provided on the housing (2) for mounting the temperature sensor (18). One temperature sensor mounting hole is located directly above the left bearing (17a), and the other temperature sensor mounting hole is located directly above the right bearing (17b). The probe of the temperature sensor (18) is in contact with the outer ring of the left bearing (17a) and the right bearing (17b).

9. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 1, characterized in that, A vent cap mounting cylinder (8) is installed at the top center of the housing (2); the central through hole of the vent cap mounting cylinder (8) is connected to the inner cavity of the oil supply ring (3); a vent cap (19) is installed at the top of the vent cap mounting cylinder (8), and an air filter is installed inside the vent cap (19).

10. The transmission shaft support structure of the aero-engine transmission system test bench according to claim 9, characterized in that, A stepped mounting hole (2b) is provided at the top center of the housing (2); the upper part of the mounting hole (2b) is provided with an internal thread for installing the vent cap mounting cylinder (8). An internal thread is provided at the lower part of the mounting hole (2b) for installing a hexagonal tapered set screw (9). The lower end of the hexagonal tapered set screw (9) is pressed against the tapered hole of the oil supply ring (3) for axial positioning of the oil supply ring (3). A through hole is provided at the center of the hexagonal tapered set screw (9). The through hole at the center of the hexagonal tapered set screw (9) is connected to the inner cavity of the oil supply ring (3).

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