Aviation starter generator and connecting structure of hollow shaft and flexible shaft of aviation starter generator

Abstract

The utility model relates to an aviation starter generator and a connecting structure of a hollow shaft and a flexible shaft thereof, belongs to the technical field of aviation starter generators, and solves the problems of high processing time and cost and poor interchangeability in the prior art. According to the utility model, the flexible shaft comprises a first end and a second end, and the first end extends into a central through hole of the hollow shaft from the front end of the hollow shaft; a plurality of annular bosses are arranged on the peripheral surface of the flexible shaft; a central through hole of the hollow shaft is a stepped hole, and the annular bosses are respectively in clearance fit with one section of the stepped hole so as to ensure the coaxiality; a flat key is arranged between the flexible shaft and the hollow shaft to transmit torque; the hollow shaft and the flexible shaft are axially limited by adopting two step surfaces and are fastened by adopting bolts. The two annular bosses are adopted for guaranteeing coaxiality, the two step faces and the bolts are adopted for axial limiting, and the flat keys are adopted for transmitting torque, so that connection reliability is guaranteed, manufacturing difficulty and machining cost are reduced, and meanwhile rapid maintenance and replacement of the flexible shaft are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of aviation starter generators, in particular to an aviation starter generator and a connection structure of a hollow shaft and a flexible shaft thereof. Background Art

[0002] The aviation starter generator is installed on the auxiliary power unit of the engine and is used to start the engine and provide power. During the process of starting the engine, the starter generator works in an electric state to start the engine. After the engine is started and enters the normal working state, the starter generator works in a power generation state to provide direct current to the power grid on the aircraft.

[0003] The connection or fastening methods between the flexible shaft and the hollow shaft of the existing domestic aviation starter generator are mainly:

[0004] 1. Half-moon key + cone, tighten with nut

[0005] The flexible shaft is installed inside the hollow shaft. The front end of the flexible shaft meshes with the gear in the engine transmission case through the external spline, and the rear end of the flexible shaft meshes with the hollow shaft through the half-moon key. The torque is transmitted from the flexible shaft to the hollow shaft. The flexible shaft and the hollow shaft are matched through the cone to ensure coaxiality. The cone processing accuracy is high, and the cone of the transmission shaft and the hollow shaft must be ground to make the contact area reach more than 95%. The processing is time-consuming and costly, and the interchangeability is poor. When installing the half-moon key, the keyway is difficult to align, and the installation is time-consuming.

[0006] 2. Fit the cylindrical involute spline tooth side and lock the nut.

[0007] The flexible shaft is installed inside the hollow shaft, and the flexible shaft and the hollow shaft are meshed with involute splines to transmit torque. It is difficult to process involute splines inside the hollow shaft, and a special broaching machine and a customized broaching tool are required for processing. Most machining plants do not have broaching machines, and the processing cost is extremely high. Utility Model Content

[0008] The embodiment of the utility model aims to provide an aviation starter generator and a connection structure of its hollow shaft and a flexible shaft, which not only ensures the coaxiality of the connection, but also reduces the manufacturing difficulty and processing cost, and at the same time realizes the rapid maintenance and replacement of the flexible shaft.

[0009] On the one hand, the utility model provides a connection structure between a hollow shaft and a flexible shaft of an aviation starter generator, wherein the flexible shaft comprises a first end and a second end, and the first end of the flexible shaft extends from the front end of the hollow shaft into the central through hole of the hollow shaft; a first annular boss and a second annular boss are arranged on the outer peripheral surface of the flexible shaft, wherein the first annular boss is adjacent to the first end, and the second annular boss is adjacent to the second end, and the diameter of the first annular boss is smaller than the diameter of the second annular boss; the central through hole of the hollow shaft is a stepped hole, and the stepped hole comprises a first section, a second section, a third section, and a fourth section which are connected in sequence from the front end to the rear end of the hollow shaft and whose diameters decrease in sequence; the first annular boss is clearance-matched with the third section, and at the same time, the second annular boss is clearance-matched with the first section; the diameter of the flexible shaft is smaller than the diameter of the fourth section.

[0010] Furthermore, the first annular boss and the second annular boss are spaced apart from each other, and the coaxiality between the first annular boss and the second annular boss is ≤0.01 mm.

[0011] Furthermore, a third annular boss is provided on the outer circumferential surface of the flexible shaft, and the third annular boss is located on the side of the second annular boss adjacent to the second end, and the diameter of the third annular boss is larger than the diameter of the second annular boss; the end face of the third annular boss close to the side of the second annular boss abuts against the end face of the front end of the hollow shaft.

[0012] Furthermore, the third annular boss and the second annular boss are an integrated structure.

[0013] Furthermore, the end face of the first end of the flexible shaft is provided with a threaded hole extending along the axial direction of the flexible shaft, and the central through hole of the hollow shaft also includes a fifth section arranged at the rear end of the fourth section, and the diameter of the fifth section is greater than the diameter of the fourth section; the connecting structure also includes a flat washer, the diameter of the flat washer is greater than the diameter of the fourth section and less than or equal to the diameter of the fifth section; the flat washer is fixedly connected to the first end of the flexible shaft by a fastener, and at the same time abuts against the step surface between the fourth section and the fifth section.

[0014] Furthermore, it also includes an elastic pad, which is arranged between the head of the fastener and the flat pad.

[0015] Furthermore, the outer circumferential surface of the flexible shaft is also provided with a first keyway, which is adjacent to the first end of the flexible shaft; the fourth section of the stepped hole of the hollow shaft is provided with two symmetrical second keyways; a flat key is provided in the first keyway, and the flat key is inserted into the second keyway.

[0016] Furthermore, the flat key and the first key slot adopt an interference fit, and the flat key and the second key slot adopt a clearance fit.

[0017] Furthermore, an annular shearing groove is also provided on the outer circumferential surface of the flexible shaft, and the annular shearing groove is located between the second end and the third annular boss.

[0018] On the other hand, the utility model provides an aviation starter generator, comprising any one of the above-mentioned connection structures of a hollow shaft and a flexible shaft.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] (1) The utility model ensures the coaxiality between the flexible shaft and the hollow shaft by using the cooperation between two coaxial annular bosses and the inner wall of the stepped hole. Compared with the prior art in which the coaxiality is ensured by the cooperation between conical surfaces, the utility model ensures the connection coaxiality while reducing the manufacturing difficulty and processing cost, and can also reduce the jitter of the flexible shaft.

[0021] (2) The utility model reduces the processing difficulty and thus reduces the production cost by configuring the central through hole of the hollow shaft to be a stepped hole with successively decreasing diameters.

[0022] (3) The utility model makes the diameter of the flexible shaft smaller than the minimum diameter of the stepped hole and makes the two annular bosses fit in the clearance of the inner wall of the stepped hole, so that the assembly and disassembly are simple and the flexible shaft can be quickly repaired and replaced.

[0023] (4) The utility model adopts a flat key connection to the flexible shaft and the hollow shaft to transmit torque, which greatly reduces the processing difficulty and cost compared with the half-moon key connection method and the involute spline connection method. Two symmetrical keyways are designed on the hollow shaft to reduce the imbalance of the rotating shaft.

[0024] (5) The utility model adopts a third annular boss and a flat washer to limit the axial position of the flexible shaft from both sides respectively, and locks it by bolts, which is convenient for disassembly and assembly and has good interchangeability. When a malfunction occurs and the flexible shaft is twisted off, the flexible shaft can be pulled out by removing the bolts, and rapid replacement is achieved without removing the starter generator rotor.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by implementing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents specifically pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. In the entire drawings, the same reference symbols represent the same components.

[0027] Figure 1 It is a cross-sectional view of the connection structure of the flexible shaft and the hollow shaft of the utility model;

[0028] Figure 2 It is a structural schematic diagram of the hollow shaft in the utility model;

[0029] Figure 3 It is a structural schematic diagram of the flexible shaft in the utility model.

[0030] Figure 4 yes Figure 1 A partial enlarged view of the left side of the connection structure between the flexible shaft and the hollow shaft;

[0031] Figure 5 yes Figure 1 A partial enlarged view of the right side of the connection structure between the flexible shaft and the hollow shaft;

[0032] Figure 6 It is a schematic cross-sectional view of a type A flat key;

[0033] Reference numerals:

[0034] 1-flexible shaft; 11-first end; 12-second end; 13-first annular boss; 14-second annular boss; 15-third annular boss; 16-threaded hole; 17-first keyway; 18-annular shear groove;

[0035] 2-hollow shaft; 21-front end; 22-rear end; 23-center through hole; 231-first section; 232-second section; 233-third section; 234-fourth section; 235-fifth section; 24-second keyway;

[0036] 3-Flat key; 4-Bolt; 5-Flat washer; 6-Spring washer. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] Example 1

[0039] A specific embodiment of the utility model is as follows Figure 1 As shown, a connection structure between a hollow shaft and a flexible shaft of an aviation starter generator is disclosed.

[0040] Among them, see Figure 1-Figure 5The flexible shaft 1 includes a first end 11 and a second end 12. A plurality of annular bosses are arranged on the outer circumferential surface of the flexible shaft 1, wherein from the first end 11 to the second end 12 are a first annular boss 13, a second annular boss 14, and a third annular boss 15, respectively. The diameters of the three annular bosses increase successively, specifically: the diameter of the first annular boss 13 is less than the diameter of the second annular boss 14, and the diameter of the third annular boss 15 is less than the diameter of the third annular boss 15.

[0041] The first annular boss 13 and the second annular boss 14 are arranged at intervals, and the coaxiality between the first annular boss and the second annular boss is ≤0.01mm. Since the coaxiality between the flexible shaft 1 and the hollow shaft 2 is ensured by only one conical surface in the prior art, the coaxiality is low, which easily causes the flexible shaft 1 to vibrate during the operation of the aviation starter generator. Through the arrangement of the utility model, the coaxiality between the flexible shaft 1 and the hollow shaft 2 can be ensured to be higher, thereby reducing the vibration of the flexible shaft.

[0042] The third annular boss 15 and the second annular boss 14 are an integrated structure.

[0043] The end surface of the first end 11 of the flexible shaft 1 is provided with a threaded hole 16 extending in the axial direction of the flexible shaft. The outer peripheral surface of the first end 11 of the flexible shaft 1 is also provided with a first keyway 17, which extends in the axial direction of the flexible shaft 1. The first keyway 17 can be one or two circumferentially evenly distributed, and is used to install the flat key 3.

[0044] An annular shearing groove 18 is also provided on the outer circumferential surface of the flexible shaft 1, and the annular shearing groove 18 is located between the second end 12 and the third annular boss 15. When the motor is stalled, the transmitted torque is greater than the shearing torque of the annular shearing groove 18, and the flexible shaft will be twisted off at the position of the annular shearing groove 18, thereby protecting the engine.

[0045] See also Figure 1-Figure 5 The hollow shaft 2 includes a front end 21, a rear end 22 and a central through hole 23. The central through hole 23 is a stepped hole, which is divided into a first section 231, a second section 232, a third section 233, a fourth section 234 and a fifth section 235 from the front end 21 to the rear end 22, and the diameter decreases from the first section 231 to the fourth section 234, and the diameter of the fifth section 235 is larger than the diameter of the fourth section 234. Two second key grooves 24 are symmetrically arranged on the inner circumference of the fourth section 234 of the stepped hole.

[0046] The diameter of the first annular boss 13 of the flexible shaft 1 is equal to the diameter of the third section 233 of the stepped hole of the hollow shaft 2, and the two are clearance-matched. At the same time, the diameter of the second annular boss 14 of the flexible shaft 1 is equal to the diameter of the first section 231 of the stepped hole of the hollow shaft 2, and the two are clearance-matched. The diameter of the third annular boss 15 of the flexible shaft 1 is greater than the diameter of the first section 231 of the stepped hole of the hollow shaft 2. The diameter of the flexible shaft 1 is smaller than the diameter of the fourth section 234 of the hollow shaft 2.

[0047] The connection structure involved in the utility model further comprises a flat key 3, a bolt 4, a flat washer 5 and a spring washer 6.

[0048] The flat key 3 may be one or two. The flat key is an A-type flat key, and its cross-sectional shape is as follows: Figure 6 As shown. The flexible shaft 1 is installed into the hollow shaft 2, the arc of the A-type flat key is introduced into the keyway, the flexible shaft 1 is pressed into place, the axial positioning surface of the third annular boss 15 of the flexible shaft 1 is fitted with the end surface of the hollow shaft 2, the locking bolts, spring washers, and flat washers are tightened, and the assembly is completed.

[0049] The diameter of the flat washer 5 is larger than the diameter of the fourth section 234 of the stepped hole of the hollow shaft 2 , and is smaller than or equal to the diameter of the fifth section 235 .

[0050] See also Figure 2-Figure 4 During assembly, the flat key 3 is first installed in the first keyway 17 on the flexible shaft 1, and the flat key 3 and the first keyway 17 are interference fit. Then, the first end 11 of the flexible shaft 1 is extended from the front end 21 of the hollow shaft 2 into the central through hole 23 of the hollow shaft 2. During the extension process, the flexible shaft 1 is rotated so that the flat key 3 is inserted into the second keyway 24, and the flat key 3 and the second keyway 24 are clearance fit. Continue to extend the flexible shaft 1 until the end face of the third annular boss 15 abuts against the end face of the front end 21 of the hollow shaft 2. At this time, the first annular boss 13 is clearance fit with the third section 233 of the stepped hole, and the second annular boss 14 is clearance fit with the first section 231 of the stepped hole. Put the flat washer 5, the spring washer 6 and the bolt 4 into the central through hole 23 from the rear end 22 of the hollow shaft 2, and the bolt 4 passes through the through hole in the center of the spring washer 6 and the flat washer 5 in turn, and enters the threaded hole 16 on the first end 11 of the flexible shaft 1. The bolt 4 is tightened, and the bolt head presses the flat washer 5 onto the step surface between the fourth section 234 and the fifth section 235 , thereby completing the connection between the flexible shaft 1 and the hollow shaft 2 .

[0051] When the flexible shaft 1 breaks due to a fault, the flexible shaft 1 can be pulled out by removing the bolt 4, so that a quick replacement can be achieved without removing the starter generator rotor.

[0052] In the utility model, two annular bosses for positioning coaxiality are designed on the flexible shaft 1, and the flexible shaft 1 and the hollow shaft 2 are clearance-fitted, and the coaxiality of the flexible shaft 1 and the hollow shaft 2 is ensured by the annular bosses for positioning coaxiality.

[0053] A first keyway 17 is designed on the flexible shaft 1, two symmetrical second keyways 24 are designed inside the hollow shaft 2, and the flat key 3 is installed in the first keyway 17 of the flexible shaft 1, and the torque is transmitted from the flexible shaft 1 to the hollow shaft 2 through the flat key 3. The flexible shaft 1 can also be designed with two symmetrical first keyways 17 and two flat keys 3 installed.

[0054] A threaded hole 16 is designed at the first end 11 of the flexible shaft 1 and an axial positioning step (i.e., the end face of the third annular boss) is designed at the second end 12. An axial positioning step surface is arranged inside the hollow shaft 2. The flat washer 5 is placed on the axial positioning step surface of the hollow shaft 2. The flexible shaft 1 and the hollow shaft 2 are axially fixed by bolts 4, flat washers 5 and spring washers 6 to prevent axial movement.

[0055] The diameter of the stepped hole of the hollow shaft 2 decreases from the first section 231 to the fourth section 234, thereby reducing the difficulty of processing and assembly.

[0056] Example 2

[0057] The utility model also relates to an aviation starter generator, comprising any one of the above-mentioned connecting structures of the hollow shaft 2 and the flexible shaft 1.

[0058] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A connection structure between a hollow shaft and a flexible shaft of an aviation starter generator, characterized in that: The flexible shaft includes a first end and a second end, and the first end of the flexible shaft extends from the front end of the hollow shaft into the central through hole of the hollow shaft; a first annular boss and a second annular boss are arranged on the outer peripheral surface of the flexible shaft, wherein the first annular boss is adjacent to the first end, and the second annular boss is adjacent to the second end, and the diameter of the first annular boss is smaller than the diameter of the second annular boss; the central through hole of the hollow shaft is a stepped hole, and the stepped hole includes a first section, a second section, a third section, and a fourth section which are connected in sequence from the front end to the rear end of the hollow shaft and whose diameters decrease in sequence; the first annular boss is loosely matched with the third section, and at the same time, the second annular boss is loosely matched with the first section; the diameter of the flexible shaft is smaller than the diameter of the fourth section.

2. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 1, characterized in that: The first annular boss and the second annular boss are spaced apart from each other, and the coaxiality between the first annular boss and the second annular boss is ≤0.01 mm.

3. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 1, characterized in that: A third annular boss is also arranged on the outer circumferential surface of the flexible shaft, and the third annular boss is located on the side of the second annular boss adjacent to the second end, and the diameter of the third annular boss is larger than the diameter of the second annular boss; the end face of the third annular boss close to the side of the second annular boss abuts against the end face of the front end of the hollow shaft.

4. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 3, characterized in that: The third annular boss and the second annular boss are an integral structure.

5. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 4, characterized in that: The end face of the first end of the flexible shaft is provided with a threaded hole extending along the axial direction of the flexible shaft, and the central through hole of the hollow shaft also includes a fifth section arranged after the fourth section, and the diameter of the fifth section is larger than the diameter of the fourth section; the connecting structure also includes a flat washer, the diameter of the flat washer is larger than the diameter of the fourth section and less than or equal to the diameter of the fifth section; the flat washer is fixedly connected to the first end of the flexible shaft by a fastener, and at the same time abuts against the step surface between the fourth section and the fifth section.

6. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 5, characterized in that: Also included is an elastic pad, which is disposed between the head of the fastener and the flat pad.

7. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 1, characterized in that: The outer circumference of the flexible shaft is also provided with a first keyway, which is adjacent to the first end of the flexible shaft; the fourth section of the stepped hole of the hollow shaft is provided with two symmetrical second keyways; a flat key is provided in the first keyway, and the flat key is inserted into the second keyway.

8. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 7, characterized in that: The flat key and the first key slot are in interference fit, and the flat key and the second key slot are in clearance fit.

9. The connection structure between the hollow shaft and the flexible shaft of the aircraft starter generator according to claim 4, characterized in that: An annular shearing groove is also provided on the outer peripheral surface of the flexible shaft, and the annular shearing groove is located between the second end and the third annular boss.

10. An aviation starter generator, characterized in that: The invention comprises a connecting structure between a hollow shaft and a flexible shaft as claimed in any one of claims 1 to 9.

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