Axial displacement control type overrun clutch

Abstract

The invention relates to the technical field of aero-engine starter systems, and discloses an axial displacement control type overrun clutch which comprises a clutch body, a damper and an output shaft, the clutch body comprises a deep groove ball bearing, an input shaft, a diaphragm spring set, a spline shaft, a fixing pin, a conversion lining, a ball bearing, a driving gear, a lock washer and a locking nut; the damper comprises a retainer, a damping block and a spring, the output shaft is supported on the starter shell through a deep groove ball bearing, the input end of the output shaft is provided with end teeth, and when the driving gear stretches out and is meshed with the end teeth, the transmission function is achieved. The output end of the output shaft is of an internal spline structure and serves as a torque output connector. By means of the torque-displacement conversion characteristic of the left-hand thread pair, accurate meshing and physical isolation disengaging of the input shaft and the output shaft are achieved. A three-stage transmission control structure is adopted and comprises a torque-displacement conversion module, a damping control module and a spiral meshing module, and the technical defects that a traditional inclined strut type clutch is polluted in lubricating oil, low in torque transmission efficiency and the like are overcome.

Description

Technical Field

[0001] This invention relates to the field of aero-engine starter system technology, and in particular to an axial displacement controlled overrunning clutch, which is a clutch device based on the principle of thread torque-displacement conversion, and achieves gear engagement / disengagement through axial displacement control. Background Technology

[0002] The slant-braced overrunning clutch has wide applications in the aviation field, such as helicopter main drive systems, fixed-wing aircraft starting systems, and auxiliary power systems. Among existing publicly disclosed slant-braced overrunning clutch technologies, patent CN112324816A designs a slant-braced overrunning clutch including an inner ring, an inner cage, a wave spring, an outer cage, an outer ring, and wedges, as well as an adjusting block. This adjusting block is hinged to one cage and connected to the other cage via a drive structure. The drive structure includes a guide post and a guide rail for guiding movement. The center of gravity of the adjusting block is located on the corresponding side of the line connecting the hinge shaft and the guide post. When the slant-braced overrunning clutch is in overrunning mode, the adjusting block swings around the hinge shaft under centrifugal force, driving the two cages to rotate relative to each other via the drive structure, thereby driving all wedges to swing synchronously in the direction of disengaging from the inner and outer raceways. However, the following technical defects exist: 1. Lubricating oil contamination problem: After the work is completed, the cage and the wedge roller continue to contact and rub against each other, generating metal shavings, which leads to excessive metal abrasive particles in the lubricating oil system.

[0003] 2. Torque transmission capacity limitation: The diagonal brace structure is prone to slippage under high torque conditions.

[0004] 3. Reliability issues: Repeated impact loads can cause plastic deformation in wedge rollers. Summary of the Invention

[0005] Purpose of the invention: The present invention proposes an overrunning clutch for an air turbine starter to solve the technical defects existing in the above-mentioned background art.

[0006] Technical solution: In order to achieve the above-mentioned invention objectives, the present invention designs an axial displacement control overrunning clutch, characterized in that it includes: a clutch, a damper, and an output shaft, wherein the clutch includes a deep groove ball bearing, an input shaft, a diaphragm spring assembly, a splined shaft, a fixing pin, a conversion bushing, a ball bearing, a drive gear, a locking washer, and a lock nut. A splined shaft is assembled inside the input shaft via a fixing pin. The splined shaft engages with the conversion bushing via splines. The locking nut, along with a stop washer, is fixed to the left end of the splined shaft, limiting the left end of the conversion bushing. A diaphragm spring assembly is fitted onto the splined shaft, with one end abutting against the end of the input shaft and the other end abutting against the right end of the conversion bushing. The stop washer serves as a safety feature to prevent loosening. The conversion bushing and the drive gear are engaged via a three-pronged left-hand rectangular thread. The damper includes a cage, damping blocks, and springs. The cage is equipped with multiple damping blocks in three sections. Each damping block is equipped with a spring on its outer ring. The tension of the spring provides positive pressure to the drive gear, thereby generating damping force. When the conversion bushing rotates, it drives the drive gear to rotate. The damping force of the drive gear rotating relative to the damping blocks is transmitted to the three-head left-hand rectangular thread structure, generating an axial component force to control the extension and retraction of the drive gear, thus realizing torque-displacement conversion.

[0007] The output shaft is supported on the starter housing by a deep groove ball bearing. Its input end is provided with end teeth. When the drive gear extends and meshes with its end teeth, the transmission function is realized. The output end of the output shaft has an internal spline structure, which serves as the interface for torque output.

[0008] Furthermore, the input end of the input shaft is provided with an involute spline structure, which is connected to the starter motor to transmit torque; the spline is provided with an annular groove in the middle, through which a steel wire retainer is installed to fix the spline connection structure.

[0009] Furthermore, the output end of the input shaft is provided with an internal gear that meshes with the external gear of the drive gear to achieve the purpose of torque transmission; the number of teeth of both the internal gear of the input shaft and the external gear of the drive gear is half of the standard number of teeth, which meets the angular rotation stroke requirements when the drive gear is converted from rotation to displacement.

[0010] Furthermore, the diaphragm spring assembly is an elastic element, and the elastic force can be controlled by adjusting the number of springs, which serves to limit the movement of the switching bushing and reduce axial impact.

[0011] Furthermore, the pin hole that mates with the fixed pin is machined after assembly. By adjusting the phase angle of the fixed pin and the relative angle between the drive gear and the input shaft, the stroke of the angular rotation during the rotation-displacement conversion of the drive gear is controlled.

[0012] Furthermore, the drive gear includes a bushing, a gear, and a rivet, which are fixed together by the bushing and the gear by the rivet.

[0013] Furthermore, the input shaft is supported on deep groove ball bearings and ball bearings, and the outer ring of the ball bearings is also provided with a corrugated ring to eliminate backlash.

[0014] Furthermore, the damping block is a graphite-copper composite material, processed using powder metallurgy to give it good wear resistance and self-lubricating properties.

[0015] Working principle of this invention: Start-up process (working process) When the starter motor starts working, the torque is transmitted to the input shaft through the spline structure. The input shaft drives the spline shaft to rotate, which in turn drives the shift bushing to rotate. When the shift bushing drives the drive gear to rotate through the three-start left-hand rectangular thread structure, it is resisted by the damping block, causing the three-start left-hand rectangular thread pair to generate an axial component force, pushing the drive gear to move towards the output shaft. When the input shaft rotates to mesh with the external gear of the drive gear, the drive gear stops moving axially and reaches the end gear of the output shaft to mesh, completing the work of transmitting torque.

[0016] Disconnection process Once the start-up is complete, the starter stops outputting torque, the positive thrust of the drive gear disappears, the drive gear disengages from the output shaft, and the rotational resistance of the starter triggers the rectangular thread pair to generate a reverse thrust, which drives the drive gear away from the output shaft, completing the disengagement process.

[0017] After disengaging from its operating state, the damper activates during the aircraft's pitching process to prevent the drive gear from moving freely.

[0018] Technical Effects: This invention is an axial displacement control overrunning clutch based on the principle of threaded torque-displacement conversion. Through the torque-displacement conversion characteristics of the left-hand threaded pair, it achieves precise engagement and physical disengagement of the input and output shafts. It innovatively adopts a three-stage transmission control structure, including a torque-displacement conversion module, a damping control module, and a helical engagement module, solving the technical defects of traditional inclined-brace clutches such as oil contamination and low torque transmission efficiency. Practical verification shows that a physical isolation gap of over 0.5mm is achieved after operation, and the oil contamination index is significantly reduced. Torque transmission capacity is significantly improved: gear transmission efficiency η≧98%, and the maximum load torque is increased to 500 N•m. Attached Figure Description

[0019] Figure 1 This is an exploded view of the present invention; Figure 2 This is a working diagram of the present invention; The components are: 1. Deep groove ball bearing, 2. Output shaft, 3. Spring, 4. Cage, 5. Damping block (12 pieces made of graphite-copper composite material), 6. Wave spring, 7. Locking nut, 8. Locking washer, 9. Drive gear, 10. Converter bushing (Tr28×88 / 3), 11. Ball bearing, 12. Fixing pin, 13. Spline shaft (involute spline, module 0.5, number of teeth 28), 14. Diaphragm spring assembly, 15. Input shaft, and 16. Deep groove ball bearing. Detailed Implementation

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings or specific implementation examples. It should be noted that some (but not all) of the disclosed examples are shown in the drawings. In fact, many different examples can be described, and these examples should not be construed as limited to the examples set forth herein. Rather, these examples are described to better demonstrate the positive effects of the present invention, and all aspects not detailed herein are considered to be well-known or conventional techniques in the art.

[0021] See appendix Figure 1 , Figure 2 The present invention specifically designs an axial displacement control overrunning clutch, the overall structure of which includes a clutch, a damper, and an output shaft. The clutch includes a deep groove ball bearing 16, an input shaft 15, a diaphragm spring assembly 14, a spline shaft 13, a fixing pin 12, a conversion bushing 10, a ball bearing 11, a drive gear 9, a stop washer 8, and a locking nut 7.

[0022] A splined shaft 13 is assembled inside the input shaft 15 via a fixing pin 12. The splined shaft 13 engages with the conversion bushing 10 via splines. The locking nut 7, in conjunction with a stop washer 8, is fixed to the left end of the splined shaft 13, limiting the left end of the conversion bushing 10. The diaphragm spring assembly 14 is fitted onto the splined shaft 13. One end of the diaphragm spring assembly 14 abuts against the end of the input shaft 15, and the other end abuts against the right end of the conversion bushing 10. The stop washer 8 serves as a safety device to prevent loosening. The conversion bushing 10 engages with the drive gear 9 via a three-pronged left-hand rectangular thread.

[0023] The damper includes a retainer 4, damping blocks 5, and springs 3. The retainer 4 is equipped with 12 damping blocks 5 in three sections. Springs 3 are installed on the outer ring of the damping blocks 5. The tension of the springs 3 provides positive pressure to the drive gear 9 for the damping blocks 5, thereby generating damping force. When the conversion bushing 10 rotates, it drives the drive gear 9 to rotate. The damping force of the drive gear 9 rotating relative to the damping blocks 5 is transmitted to the three-head left-hand rectangular thread structure, generating an axial component force to control the extension and retraction of the drive gear 9, thereby realizing torque-displacement conversion.

[0024] The output shaft 2 is supported on the starter housing by a deep groove ball bearing 1. Its input end is provided with end teeth. When the drive gear 9 extends and meshes with its end teeth, the transmission function is realized. The output end of the output shaft 2 has an internal spline structure, which serves as the interface for torque output.

[0025] In a specific implementation example, the input end of the input shaft 15 is provided with an involute spline structure, which connects to the starter motor to transmit torque. An annular groove is provided in the middle of the spline, through which a wire retainer is installed to fix the spline connection structure. The output end of the input shaft 15 is provided with an internal gear, which meshes with the external gear of the drive gear 9 to achieve torque transmission. The number of teeth on both the internal gear of the input shaft 15 and the external gear of the drive gear 9 is half the standard number of teeth, satisfying the angular rotational stroke requirement of the drive gear 9 during rotation-displacement conversion. The drive gear 9 includes a bushing 9.1, a gear 9.2, and a rivet 9.3, which are fixed together by the bushing 9.1 and the gear 9.2 via the rivet 9.3.

[0026] Working principle Start-up process (working process) When the starter motor starts working, the torque is transmitted to the input shaft 15 through the spline structure. The input shaft 15 drives the spline shaft 13 to rotate, and the spline shaft 13 drives the conversion bushing 10 to rotate. When the conversion bushing 10 drives the drive gear 9 to rotate through the three-start left-hand rectangular thread structure, it is resisted by the damping block 5, which causes the three-start left-hand rectangular thread pair to generate an axial component force, pushing the drive gear 9 to move towards the output shaft 2. When the input shaft 15 rotates to mesh with the external gear of the drive gear 9, the drive gear 9 stops moving axially and reaches the end gear meshing with the output shaft 2, completing the work of transmitting torque.

[0027] Disconnection process Once the start-up is complete, the starter stops outputting torque, the positive thrust of the drive gear 9 disappears, the drive gear 9 disengages from the output shaft 2, and the rotational resistance of the starter triggers the rectangular thread pair to generate a reverse thrust, which drives the drive gear 9 away from the output shaft 2, thus completing the disengagement process.

[0028] After disengaging from its operating state, the damper activates during the aircraft's pitching process to prevent the drive gear 9 from moving freely.

[0029] The overrunning clutch designed in this invention adopts a three-stage transmission control structure: 1. Torque-Displacement Conversion Module: Composed of input shaft 15, drive gear 9, and conversion bushing 10, generating an axial displacement D=3.8. +0.3 mm, the axial displacement and the rectangular thread lead and gear set parameters satisfy the geometric relationship of Equation 1.

[0030] ··················(1) In formula (1): D—Axial displacement stroke of the drive gear, mm; L—Left-hand rectangular thread lead L, mm; θ — the rotational clearance of the gear set, in degrees; ΔX — Height difference between the end faces of the conversion bushing 10 and the driving gear 9 (the conversion bushing is lower than the driving gear), mm.

[0031] 2. Damping control module: An asymmetric friction pair consisting of a damping block 5 preloaded by spring 3 and a cage 4, with a static friction coefficient μ. S =0.12~0.15, friction coefficient change rate d μ / d n ≤0.0005 (rpm).

[0032] 3. Helical meshing module: It consists of the driving gear 9 and 12 pairs of helical gears on the output shaft 2.

[0033] Combination Figure 2 Workflow Description 1. Initial state: Input shaft 15 is stationary, spring 3 presses damping block 5 through retainer 4, and driving gear 8 and driven gear 2 are axially separated.

[0034] 2. Start-up phase: When the input shaft rotates, the threaded pair of the conversion bushing 10 generates axial thrust, which drives the drive gear 9 to move axially by 3.8mm to complete the meshing.

[0035] 3. Torque transmission: When the output speed reaches 5000 rpm, the maximum torque transmitted by the gear pair shall not be less than 500 N·m.

[0036] 4. Disengagement stage: After the input torque disappears, the rotational resistance of the starter triggers the threaded pair to move in the opposite direction, completing the disengagement.

[0037] The above specific embodiments or examples are only used to explain the technical solutions of the present invention and are not intended to limit the present application. Parts not described in detail are considered to be conventional technical means or common knowledge in the field. It can be understood by those skilled in the art that, based on the design concept of the present application, the technical solutions described in the foregoing embodiments can be adapted, or some or all of the technical features can be equivalently replaced. These modifications, equivalent replacements, and adaptive improvements do not depart from the technical essence of the present invention and should all be covered within the protection scope of the present application.

Claims

1. An axial displacement controlled overrunning clutch characterized by, Comprise: Clutch, damper, output shaft, the clutch comprises deep groove ball bearing (16), input shaft (15), diaphragm spring group (14), spline shaft (13), fixed pin (12), conversion bushing (10), ball bearing (11), driving gear (9), stop washer (8), locking nut (7); The input shaft (15) is assembled with spline shaft (13) through fixed pin (12), spline shaft (13) is matched with conversion bushing (10) through spline, locking nut (7) is matched with stop washer (8) and is fixed on the left end of spline shaft (13), and the left end of conversion bushing (10) is limited, diaphragm spring group (14) is sleeved on spline shaft (13), one end of diaphragm spring group (14) abuts with the end of input shaft (15), the other end abuts with the right end of conversion bushing (10), and stop washer (8) functions as safety lock washer; conversion bushing (10) is matched with driving gear (9) through three head left-handed rectangular thread; The damper comprises retainer (4), damping block (5) and spring (3), the retainer (4) is assembled with a plurality of damping blocks (5) in three areas, the outer circle of each damping block (5) is assembled with spring (3), and the tension of spring (3) provides positive pressure of damping block (5) to driving gear (9), so as to generate damping force; when conversion bushing (10) rotates, driving gear (9) is driven to rotate, and the damping force of driving gear (9) relative to damping block (5) is transmitted to three head left-handed rectangular thread structure, axial component force is generated to control driving gear (9) to stretch and shrink, and torque-displacement conversion is realized; The output shaft (2) is supported on the starter housing through deep groove ball bearing (1), and the input end is provided with end teeth; when driving gear (9) is extended and engaged with the end teeth, the transmission function is realized; the output end of output shaft (2) is an internal spline structure, which is used as the interface for torque output; When the starter starts to work, torque is transmitted to input shaft (15) through spline structure, input shaft (15) drives spline shaft (13) to rotate, spline shaft (13) drives conversion bushing (10) to rotate, and conversion bushing (10) drives driving gear (9) to rotate through three head left-handed rectangular thread structure; when conversion bushing (10) rotates, it is resisted by damping block (5), so that three head left-handed rectangular thread pair generates an axial component force, and driving gear (9) is pushed to move towards output shaft (2); when input shaft (15) rotates to engage with the external gear of driving gear (9), driving gear (9) stops axial movement and reaches the engagement with the end teeth of output shaft (2), and the transmission torque is completed; When the starting is completed, the starter stops torque output, the positive thrust of driving gear (9) disappears, driving gear (9) exits the engagement with output shaft (2), and the rotating resistance of the starter triggers the reverse thrust of the rectangular thread pair, driving gear (9) moves away from output shaft (2), and the disengagement work is completed.

2. A axial displacement controlled overrunning clutch as in claim 1, wherein, Comprise: The input end of input shaft (15) is provided with involute spline structure, which is connected with the starter through spline structure and transmits torque; the ring groove is arranged in the middle of spline, and the steel wire ring is installed in the groove to fix the spline connection structure.

3. An axial displacement controlled overrunning clutch as in claim 2, wherein, The output end of the input shaft (15) is provided with an internal gear, which is engaged with the external gear of the driving gear (9) to achieve torque transmission. The number of teeth of the internal gear of the input shaft (15) and the external gear of the driving gear (9) is half of the standard number of teeth, which meets the requirement of the angular rotation stroke when the driving gear (9) is rotated and displaced.

4. An axial displacement controlled overrunning clutch as in claim 1, wherein, The diaphragm spring group (14) is an elastic element, which can control the elastic force by adjusting the number, and plays a role of limiting the conversion bushing (10) and reducing the axial impact.

5. An axial displacement controlled overrunning clutch as in claim 1, wherein, The pin hole matched with the fixed pin (12) is formed by combined machining, and the phase angle of the fixed pin is adjusted, and the relative angle of the driving gear and the input shaft is adjusted, so as to control the stroke of the angular rotation when the driving gear is rotated and displaced.

6. An axial displacement controlled overrunning clutch as in claim 1 or 5 wherein, The driving gear (9) comprises a bushing (9.1), a gear (9.2) and a rivet (9.3), and the bushing (9.1) and the gear (9.2) are fixed by the rivet (9.3).

7. An axial displacement controlled overrunning clutch as in claim 1, wherein, The input shaft (15) is supported on the deep groove ball bearing (16) and the ball bearing (11), and the outer ring of the ball bearing (11) is further provided with a wave ring (6) to play a role of eliminating clearance.

8. An axial displacement controlled overrunning clutch as in claim 1, wherein, The damping block is a graphite-copper composite material, which is processed by a powder metallurgy process.

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