Combined aero-engine crankshaft
Through the design of a combined aircraft engine crankshaft and the use of rolling bearings and key connection structures, the processing difficulty and bearing wear problems of multi-crank crankshafts are solved, cost reduction and reliability improvement are achieved, and the needs of different aircraft models are met.
Patent Information
- Application Number
- CN202422651541.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-10-14
- Estimated Expiration
- 2034-10-31
AI Technical Summary
The existing multi-crank aircraft engine crankshaft is difficult to process and has high manufacturing costs, and the bearings are severely worn, which affects the service life and reliability of the engine.
A combined aircraft engine crankshaft is used, consisting of a left crank, a right crank and an expansion component. Rolling bearings and a key connection structure are used to replace traditional bearings to achieve the installation of rolling bearings on the crankshaft. The number of cranks can be increased or decreased through the expansion component to meet the needs of different models.
It reduces the processing difficulty and manufacturing cost of multi-crank crankshafts, extends the service life of the main journal, improves the reliability and transmission efficiency of the engine, and the high speed and low friction characteristics of the rolling bearing solve the problem of bearing wear.
Smart Images
Figure CN223434614U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of aviation engines, in particular to a combined aviation engine crankshaft. Background Art
[0002] A piston aircraft engine primarily consists of a crankshaft, connecting rods, pistons, cylinders, a valve train, and a casing. The cylinders are often arranged horizontally. Common horizontally opposed aircraft engines include opposed four-cylinder, opposed six-cylinder, and opposed eight-cylinder models. The crankshaft in each aircraft engine must match the cylinder layout. The more cylinders there are, the more crankshafts there are.
[0003] Existing multi-crank crankshafts often utilize a one-piece forging structure, which is difficult to manufacture and has high manufacturing costs. This is especially true as the number of cranks increases, where manufacturing costs increase exponentially. Furthermore, the main journals of multi-crank crankshafts can only be supported by split bearings, which are sliding bearings suitable only for medium- and low-speed engines. Aircraft engines, on the other hand, are high-speed engines. During operation, not only are the bearings susceptible to wear, but abrasive particles released from the bearings can also cause rapid wear of the main journals. Therefore, producing multi-crank crankshafts using one-piece molding would not only exponentially increase the crankshaft's manufacturing cost, but also cause premature wear of the main journals. Utility Model Content
[0004] In order to overcome the deficiencies in the background art, the present invention discloses a combined aircraft engine crankshaft, the purpose of which is:
[0005] 1. Reduce the processing difficulty and manufacturing cost of multi-crank crankshafts;
[0006] 2. Replace the bearing shell to realize the installation of rolling bearing on the crankshaft and solve the wear problem of the main journal.
[0007] Specifically, the present invention adopts the following technical solutions:
[0008] A combined aircraft engine crankshaft, the crankshaft consisting of a left crank, a right crank and at least one expansion assembly, wherein the left crank and the right crank have a first main journal and a first connecting rod journal; the expansion assembly includes a pair of expansion cranks, a pair of crank plates, a connecting sleeve and a rolling bearing, wherein the expansion crank has a second main journal and a second connecting rod journal; the crank plate has two pin holes for interference connection with the second connecting rod journal or the first connecting rod journal; the connecting sleeve is arranged between the pair of expansion cranks for interference connection with the second main journal on the pair of expansion cranks; the rolling bearing is mounted on the connecting sleeve for supporting the second main journal.
[0009] After implementing the above technical solution, compared with the background technology, the beneficial effects produced are:
[0010] 1. The number of crank configurations can be increased or decreased at will through expansion components to meet the needs of various models;
[0011] 2. The expansion components are universal parts. By combining the expansion components, the processing difficulty and manufacturing cost of multi-crank crankshafts can be greatly reduced;
[0012] 3. The installation of rolling bearings on the crankshaft is realized. Rolling bearings have the advantages of high speed, low friction and long service life. Moreover, the wear surface is limited to the rolling elements and the inner and outer ring tracks, which fundamentally solves the problem of easy wear of the main shaft neck.
[0013] To further improve the technical solution, a key connection structure is provided between the second connecting rod journal and the connecting sleeve.
[0014] The implementation of the above technical solution has the beneficial effect of maintaining a strict angular relationship between the cranks of a multi-crank crankshaft. The key connection structure provided between the second connecting rod journal and the connecting sleeve not only positions and guides the two extended cranks, ensuring they maintain the correct angular relationship, but also acts as a key connection. If the interference fit between the second connecting rod journal and the connecting sleeve fails, the key connection structure prevents the two extended cranks from rotating relative to each other.
[0015] To further improve the technical solution, a spline connection structure is provided between the second connecting rod journal and the connecting sleeve.
[0016] After implementing the above technical solution, the beneficial effect is: the spline connection structure is a type of key connection structure. Compared with flat keys or semicircular keys, the spline has a larger transmission torque and can better ensure that the two expansion cranks do not rotate relative to each other.
[0017] To further improve the technical solution, the number of keyways in the spline connection structure is 12.
[0018] After implementing the above technical solution, the beneficial effect is: the number of spline grooves is set to 12, and 12 is the lowest common multiple of 2, 3, and 4, which can simultaneously meet the positioning needs of the offset angles between the extended cranks of opposed four-cylinder, opposed six-cylinder, and opposed eight-cylinder aircraft engines.
[0019] To further improve the technical solution, there are two rolling bearings, and the expansion component further includes a spacer sleeve, which is arranged between the two rolling bearings.
[0020] After implementing the above technical solution, the beneficial effects are: providing two rolling bearings can increase the total bearing capacity of the main shaft neck, providing a spacer can separate the two rolling bearings and axially limit the two rolling bearings.
[0021] To further improve the technical solution, the rolling bearing is a needle roller bearing.
[0022] After implementing the above technical solution, the beneficial effects produced are: compared with other rolling bearings, needle roller bearings have a smaller outer diameter, a higher rotation speed and a greater load-bearing capacity.
[0023] To further improve the technical solution, an oil inlet hole and an oil groove are provided on the spacer sleeve for lubricating the rolling bearing.
[0024] After the above technical solution is implemented, the beneficial effect produced is: a lubrication system is provided on the casing, and the lubricating oil enters the rolling bearing through the oil inlet hole and the oil groove to achieve lubrication of the rolling bearing.
[0025] To further improve the technical solution, a main bearing is installed on the first main journal, and the outer diameter of the main bearing is the same as the outer diameter of the rolling bearing.
[0026] After implementing the above technical solution, the beneficial effects are: multiple bearing mounting holes are provided on the casing, the outer diameter of the main bearing is the same as the outer diameter of the rolling bearing, which facilitates boring out all the bearing mounting holes with one cut, thereby improving the consistency of the sizes of the bearing mounting holes. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Attachment Figure 1 Shown is a structural schematic diagram of the opposed four-cylinder aircraft engine crankshaft in Example 1.
[0028] Attachment Figure 2 Shown is the attached Figure 1 Schematic diagram of the decomposition structure.
[0029] Attachment Figure 3 Shown is another structural schematic diagram of an opposed four-cylinder aircraft engine crankshaft.
[0030] Attachment Figure 4 Shown is a schematic structural diagram of an opposed six-cylinder aircraft engine crankshaft.
[0031] Attachment Figure 5 Shown is a schematic structural diagram of an opposed eight-cylinder aircraft engine crankshaft.
[0032] Attachment Figure 6 Shown is a structural schematic diagram of the flat key connection structure in Example 2.
[0033] Attachment Figure 7 Shown is a structural schematic diagram of the spline connection structure in Example 3.
[0034] In the accompanying drawings: 1. Left crank; 11. First main journal; 12. First connecting rod journal; 2. Right crank; 3. Extension assembly; 31. Extension crank; 311. Second main journal; 312. Second connecting rod journal; 32. Crank plate; 33. Connecting sleeve; 34. Needle roller bearing; 35. Spacer sleeve; 4. Connecting rod; 5. Main bearing; 6. Flat key. DETAILED DESCRIPTION
[0035] The following describes preferred embodiments of the present invention with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. It should be noted that, in the description of the present invention, terms such as "front," "rear," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is merely for ease of description and does not indicate or imply that the device or component must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can mean fixed, detachable, or integral; mechanical or electrical; direct, indirect through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.
[0036] Example 1:
[0037] Refer to the attached Figure 1 and attached Figure 2 , attached Figure 1 The diagram shows a structural diagram of a crankshaft of an opposed four-cylinder aircraft engine. Figure 2 Shown is the attached Figure 1 Schematic diagram of the decomposition structure. Figure 1 and attached Figure 2 It can be seen that the opposed four-cylinder aircraft engine crankshaft consists of a left crank 1, a right crank 2 and an expansion assembly 3, wherein the left crank 1 and the right crank 2 have a first main journal 11 on one side and a first connecting rod journal 12 on the other side, and a connecting rod 4 is installed on the first connecting rod journal 12.
[0038] The expansion assembly 3 includes a pair of expansion cranks 31, a pair of crank discs 32, a connecting sleeve 33, and rolling bearings. The expansion crank 31 has a second main journal 311 on one side and a second connecting rod journal 312 on the other side. The connecting rod 4 is mounted on the second connecting rod journal 312. The crank disc 32 has two pin holes, one for interference connection with the first connecting rod journal 12 and the other for interference connection with the second connecting rod journal 312. The connecting sleeve 33 is disposed between the pair of expansion cranks 31 and is used for interference connection with the second main journal 311 on the pair of expansion cranks 31. The interference connection process can be a room temperature interference pressing process or a low temperature cold shrinkage pressing process.
[0039] Rolling bearings are mounted on the connecting sleeve 33 to support the second main journal 311. In this embodiment, the rolling bearings are two needle roller bearings 34. Needle roller bearings 34 have the advantages of a small outer diameter, high rotational speed, and high load capacity. It is worth noting that the rolling bearings can also be ball bearings or roller bearings.
[0040] It's also worth noting that the rolling bearing is installed on the connecting sleeve 33 before the connecting sleeve 33 and the second main journal 311 are press-fitted together, thus completing the installation of the rolling bearing on the crankshaft. Because rolling bearings offer the advantages of high speed, low friction, and long service life, and their wear surfaces are limited to the rolling elements and the inner and outer raceways, the problem of easy wear on the second main journal 311 is fundamentally resolved.
[0041] A spacer sleeve 35 is provided between the two needle roller bearings 34 to separate the two rolling bearings and to limit their axial position. The spacer sleeve 35 is provided with an oil inlet hole and an oil groove. During operation, lubricating oil enters the rolling bearings through the oil inlet hole and the oil groove to lubricate the needle roller bearings 34.
[0042] A main bearing 5 is mounted on the first main journal 11 of the left crank 1 and the right crank 2. The outer diameter of the main bearing 5 is the same as the outer diameter of the two needle bearings 34. Such a design facilitates the processing of the bearing mounting holes on the casing.
[0043] Refer to the attached Figure 3 , attached Figure 3 The diagram shows another structural diagram of the crankshaft of an opposed four-cylinder aircraft engine. Figure 1 and attached Figure 3 It can be seen that the attached Figure 1 The misalignment angle between the second connecting rod journal 312 of the pair of expansion cranks 31 is 0°. Figure 3 A pair of expansion cranks 31 in the middle, the misalignment angle between its second connecting rod journal 312 is 180 °. Obviously, these two kinds of crankshafts just have differences in the firing order.
[0044] Refer to the attached Figure 4 , attachedFigure 4 The diagram shows the structure of the crankshaft of an opposed six-cylinder aircraft engine. Figure 4 It can be seen that the six-cylinder aircraft engine crankshaft consists of a left crank 1, a right crank 2 and two expansion components 3, and the offset angles of each expansion crank 31 are 0°, 120° and 240° respectively.
[0045] Refer to the attached Figure 5 , attached Figure 5 The diagram shows the structure of the crankshaft of an opposed eight-cylinder aircraft engine. Figure 5 It can be seen that the eight-cylinder aircraft engine crankshaft consists of a left crank 1, a right crank 2 and three expansion components 3, and the offset angles of each expansion crank 31 are 0°, 90°, 180° and 270° respectively.
[0046] As can be seen from Example 1, by adding or removing expansion components, various types of aircraft engines can be matched, significantly reducing the processing difficulty and manufacturing cost of multi-crank crankshafts. In addition, the installation of rolling bearings on the crankshaft is achieved, fundamentally solving the problem of easy wear of the second main journal.
[0047] Example 2:
[0048] In Example 1, an interference fit connection is adopted between a pair of expansion cranks 31 and the connecting sleeve 33. Firstly, during the pressing process, the misalignment angle between the pair of expansion cranks 31 cannot be strictly guaranteed; secondly, the interference fit connection has the risk of failure. Once it fails, serious accidents such as the piston hitting the valve may occur.
[0049] Refer to the attached Figure 6 , attached Figure 6 The diagram shows the structure of the key connection structure. Figure 6 It can be seen that a flat key connection structure is provided between the second connecting rod journal 312 and the connecting sleeve 33 .
[0050] Specifically, an external keyway is provided on the second connecting rod journal 312, an internal keyway is provided in the connecting sleeve 33, and a flat key 6 is provided between the second connecting rod journal 312 and the connecting sleeve 33. When pressed together, the flat key 6 is fixed on the internal keyway of the connecting sleeve 33, and the two extended cranks 31 are positioned and guided by the cooperation between the flat key 6 and the external keyway.
[0051] For a multi-crank crankshaft, the expansion cranks 31 maintain a strict angular relationship with each other. A key connection structure is provided between the second connecting rod journal 312 and the connecting sleeve 33. Firstly, it can position and guide the two expansion cranks, ensuring that they maintain the correct angular relationship. Secondly, it acts as a key connection. If the interference fit between the second connecting rod journal 312 and the connecting sleeve 33 fails, the key connection structure ensures that the two expansion cranks 31 do not rotate relative to each other.
[0052] Example 3:
[0053] Refer to the attached Figure 7 , attached Figure 7 The diagram shows the structure of the spline connection structure. Figure 7 It can be seen that a spline connection structure is provided between the second connecting rod journal 312 and the connecting sleeve 33 .
[0054] Specifically, an external spline is provided on the second connecting rod journal 312, and an internal spline is provided within the connecting sleeve 33. During press-fitting, the external and internal splines cooperate to position and guide the two expansion cranks 31. Compared to flat keys or woodruff keys, splines transmit greater torque and better prevent the two expansion cranks 31 from rotating relative to each other.
[0055] As can be seen from Example 1, for an opposed four-cylinder aircraft engine, the cranks are offset by 0° or 180°. Therefore, at least two spline grooves are required to achieve positioning between the extended cranks. For an opposed six-cylinder aircraft engine, the cranks are offset by 0°, 120°, and 240°. Therefore, at least three spline grooves are required to achieve positioning between the extended cranks. For an opposed eight-cylinder aircraft engine, the cranks are offset by 0°, 90°, 180°, and 270°. Therefore, at least four spline grooves are required to achieve positioning between the extended cranks.
[0056] To increase the versatility of the expansion crank, the number of spline grooves is set to 12. 12 is the lowest common multiple of 2, 3, and 4, and can simultaneously meet the positioning requirements of the offset angles between the expansion cranks of opposed four-cylinder, opposed six-cylinder, and opposed eight-cylinder aircraft engines.
[0057] It should be understood that the crankshaft can also be adapted to horizontally opposed twelve-cylinder and sixteen-cylinder aircraft engines, as well as in-line multi-cylinder aircraft engines and V-type multi-cylinder aircraft engines.
[0058] Parts not described in detail are prior art. Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of protection of the present invention is defined by the appended claims and their equivalents.
Claims
1. A combined aircraft engine crankshaft, characterized by: The crankshaft consists of a left crank, a right crank and at least one expansion component, wherein the left crank and the right crank have a first main journal and a first connecting rod journal; the expansion component includes a pair of expansion cranks, a pair of crank plates, a connecting sleeve and a rolling bearing, wherein the expansion crank has a second main journal and a second connecting rod journal; the crank plate has two pin holes for interference connection of the second connecting rod journal or the first connecting rod journal; the connecting sleeve is arranged between the pair of expansion cranks for interference connection of the second main journal on the pair of expansion cranks; the rolling bearing is installed on the connecting sleeve for supporting the second main journal.
2. The combined aircraft engine crankshaft according to claim 1, wherein: A key connection structure is provided between the second connecting rod journal and the connecting sleeve.
3. The combined aircraft engine crankshaft according to claim 1, wherein: A spline connection structure is provided between the second connecting rod journal and the connecting sleeve.
4. The combined aircraft engine crankshaft according to claim 3, characterized in that: The number of keyways in the spline connection structure is 12.
5. The combined aircraft engine crankshaft according to claim 1, characterized in that: There are two rolling bearings, and the expansion component further includes a spacer sleeve, which is arranged between the two rolling bearings.
6. The combined aircraft engine crankshaft according to claim 5, characterized in that: The rolling bearing is a needle roller bearing.
7. The combined aircraft engine crankshaft according to claim 5, characterized in that: An oil inlet hole and an oil groove are provided on the spacer sleeve for lubricating the rolling bearing.
8. The combined aircraft engine crankshaft according to claim 5, 6 or 7, characterized in that: A main bearing is mounted on the first main journal, and the outer diameter of the main bearing is the same as the outer diameter of the rolling bearing.