An asymmetric self-aligning roller bearing for a fan and its design method

Abstract

An asymmetric self-aligning roller bearing for a fan and its design method. The asymmetric self-aligning roller bearing is composed of an outer ring, an inner ring, a row of spherical rollers A, a row of spherical rollers B, and a cage. The bearing has different contact angles. The outer ring raceway is a spherical arc with a continuous radius value R, and the center of the sphere O is at the demarcation point of the widths B1 and B2 on the bearing center line. The long spherical rollers and the short spherical rollers have the same maximum diameter and spherical radius value, but different lengths. At the same time, this solution also discloses the design method of the bearing of the present invention. The bearing with different contact angles described in the present invention is applicable to the working conditions of a wind power main shaft, has a large axial load-bearing capacity, and the same diameter and spherical radius value of the double-row rollers make the manufacturing cost lower.

Description

Technical Field

[0001] The present invention relates to the technical field of bearings, and specifically to an asymmetric spherical roller bearing for a fan and its design method, which is mainly applied to the main shaft position of wind power generation machinery. Background Art

[0002] Spherical roller bearings (also known as self-aligning roller bearings) are mainly applied to mechanical occasions with misaligned shafts. Their self-aligning performance allows the transmission shaft to swing slightly. The self-aligning angle is generally in the range of 0 to 2°. They can withstand radial loads and axial loads. Commonly used spherical roller bearings have a double-row symmetric structure. However, due to the large axial force on the fan main shaft, one row of the double-row spherical roller bearing is often subjected to a large load, while the other row is subjected to a small load or even no load. With the country's increasing attention to green energy, fan equipment has received more and more attention.

[0003] The literature "Optimal Design of the Structure of Double-Row Spherical Roller Bearings for Wind Turbine Main Shafts (published in the 6th issue of the Journal of Bearing in 2018)" analyzed the force conditions of the fan main shaft and the load conditions of the double-row spherical roller bearings, and proposed an asymmetric spherical roller structure for the single-sided load condition, with a contact angle of 13.5° for one row and 9.5° for the other row. It improved the load within the bearing and extended the bearing service life. However, the details of the two rows of rollers were not elaborated.

[0004] Patent CN111720434A (a self-aligning roller bearing and heat treatment process suitable for axial and radial offset load conditions) discloses an asymmetric self-aligning roller bearing. In addition to different contact angles, it also discloses that the two rows of rollers are composed of long rollers and short rollers, and the maximum diameter of the short rollers is smaller than that of the long rollers. It shows that the ratio of the length of the long rollers to the length of the short rollers is (1.5 - 2.5):1; the ratio of the length of the long rollers to the axial length of the inner ring is (0.4 - 0.6):1; the ratio of the diameter of the long rollers to the diameter of the short rollers is (1 - 1.5):1. This ratio still lacks operability in practical applications and cannot accurately calculate the roller size, contact angle size, etc. in bearing design. For technicians, it is impossible to calculate the internal dimensions of the bearing and draw engineering drawings according to a certain process only knowing the bearing installation space.

[0005] Patent CN212003955 (a double-row asymmetric self-aligning roller bearing for improving single-axial load-bearing capacity) discloses a double-row asymmetric self-aligning roller bearing with a wide outer ring and a narrow inner ring structure, describes that the two rows of rollers have different lengths and diameters, and is applied to a cement tanker. Except for the structure description, no more design parameter details are disclosed.

[0006] Patent CN104389898 (Asymmetric Structure Self-aligning Roller Bearing) discloses a nylon cage asymmetric double-row self-aligning roller bearing, which only describes one row of large rollers and one row of small rollers without disclosing more details.

[0007] As can be seen from the above prior art, the understanding of the asymmetric double-row self-aligning roller bearing is mostly about describing one row of large rollers and one row of small rollers in terms of structure, with different contact angles. There is still no specific parameter calculation method available for engineers and technicians to operate. Under the premise of knowing the bearing installation space (bearing outer dimensions), there is no public information on how to determine the contact angle size and how to determine the roller size. There are technical difficulties in the design and development of asymmetric double-row self-aligning roller bearings. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides an asymmetric self-aligning roller bearing for a fan and its design method.

[0009] The technical solution adopted by the present invention is: an asymmetric self-aligning roller bearing for a fan, which is composed of an outer ring, an inner ring, row A spherical rollers, row B spherical rollers and a cage. Among them, row A spherical rollers are short spherical rollers, and row B spherical rollers are long spherical rollers. The long spherical rollers and short spherical rollers have the same maximum diameter Da, the same spherical radius Ra and different contact angles. The contact angle width of row A spherical rollers is set as B 1 , and the contact angle width of row B spherical rollers is B 2 . The raceway of the outer ring is a spherical arc with a continuous radius value R, and its center of the sphere O is at the demarcation point of the width B 1 and B 2 on the bearing center line.

[0010] A design method for an asymmetric self-aligning roller bearing for a fan includes the following steps:

[0011] S1. According to the known outer dimensions of the bearing: inner diameter d, outer diameter D and total width B, set the contact angle difference α c ;

[0012] S2. Initially determine the double-row width ratio m, and obtain the contact angle width of row A spherical rollers as and the contact angle width of row B spherical rollers as

[0013] S3. Obtain the contact angle according to the conditions in step S2;

[0014] S4. Calculate the contact angle difference α c and determine α c =|α 1 -α 2 |. If the set value in step S1 is not reached, adjust the m value and loop through steps S2 - S3 until it is reached;

[0015] S5. According to the formula Da = K 1 (D - d), L 1 = K 2 B 1 , L 2 = K 2 B 2 and R = 0.5D - K 3 Calculate the maximum diameter Da, roller length L 1 of the spherical roller and L 2 and the outer ring raceway ball diameter R, where the coefficient K 1 = 0.24 - 0.27, K 2 = 0.74 - 0.78, K 3 = 0.09 - 0.11;

[0016] S6. Determine the inner ring and cage dimensions according to the roller dimensions.

[0017] As a preferred solution, in step S3: The contact angle of the spherical rollers in column A The contact angle of the spherical rollers in column B

[0018] The beneficial effects of the present invention are:

[0019] Through innovative structural design, this solution provides an asymmetric self-aligning roller bearing with equal diameters but unequal lengths for a fan, using two rows of rolling elements with different sizes and contact angles to meet the use requirements of excessive axial force on the fan main shaft; at the same time, the double-row rollers have the same diameter and the same spherical radius value, making the manufacturing simpler and reducing the manufacturing cost. At the same time, the design method of the internal parameters of the bearing is disclosed for the first time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a structural schematic diagram of the asymmetric self-aligning roller bearing in the present invention;

[0022] Figure 2 It is a roller dimension diagram of the bearing of the present invention;

[0023] Figure 3 It is a design method flow chart of the present invention;

[0024] Figure 4 is the contact angle curve graph of the embodiment of the present invention;

[0025] Figure 5 is the engineering drawing of the embodiment of the present invention.

[0026] Markings in the figure: 1. Outer ring, 2. Inner ring, 3. Spherical rollers in column A, 4. Spherical rollers in column B, 5. Cage; d – inner diameter of the bearing, unit: mm; D – outer diameter of the bearing, unit: mm; B - width of the bearing, unit: mm; α 1 – contact angle of the rollers in column A, α 2 – contact angle of the rollers in column B, B 1 – contact angle width of column A, unit: mm; B 2 – contact angle width of column B, unit: mm; R – diameter of the outer ring raceway, unit: mm; D a – maximum diameter of the spherical roller, unit: mm; L 1 - length of the rollers in column A, unit: mm; L 2 - length of the rollers in column B, unit: mm; R a - spherical radius of the spherical roller, unit: mm; O - center of the outer ring raceway ball. Specific embodiments

[0027] Next, the present invention will be specifically described through exemplary embodiments. However, it should be understood that, without further description, the elements, structures, and features in one embodiment can also be beneficially combined with those in other embodiments.

[0028] It should be noted that: Unless otherwise defined, the technical terms or scientific terms used herein should have the ordinary meaning understood by those of ordinary skill in the art to which the present invention belongs. The words such as "a", "one", or "the" used in the specification and claims of this patent application for the present invention do not express a quantity limitation, but mean that there is at least one. Words such as "comprising" or "including" point out that the elements or objects appearing before "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function.

[0029] Embodiment 1

[0030] Next, in combination with the attached Figures 1-5 The overall structure and the entire design process of this embodiment will be described in detail:

[0031] Such as Figure 1As shown in the figure, the asymmetric self-aligning roller bearing with equal-diameter and unequal-length rollers for a fan consists of an outer ring 1, an inner ring 2, a row of spherical rollers A 3, a row of spherical rollers B 4, and a cage 5. Among them, the row of spherical rollers A are short spherical rollers, and the row of spherical rollers B are long spherical rollers. The asymmetric self-aligning roller bearing has different contact angles α 1 and α 2 to adapt to the working conditions with a large axial force on the main shaft of the fan. Since the inner ring 2 of the bearing is tightly fitted with the main shaft of the fan, the inner assembly composed of the inner ring 2, the row of spherical rollers A 3, the row of spherical rollers B 4, and the cage 5 will rotate with the main shaft. And when the main shaft is misaligned, the row of spherical rollers A 3 and the row of spherical rollers B 4 will adjust along the raceway of the outer ring 1 to align the main shaft. Set the contact angle width of the row of spherical rollers A as B 1 , and the contact angle width of the row of spherical rollers B as B 2 . The raceway of the outer ring 1 of the asymmetric self-aligning roller bearing is a continuous spherical arc with a radius value of Figure 1 R in 1 and B 2 . Its center of the sphere O is at the demarcation point of the widths B

[0032] As Figure 2 shown, different from the existing technology of asymmetric self-aligning roller bearings, the long spherical rollers and short spherical rollers of the present invention have the same maximum diameter Da, the same spherical radius Ra, but different lengths L 1 and L 2 . This ensures that except for the different length dimensions, the other dimensions of the two types of rollers are the same. In manufacturing, the same initial dimension materials can be used for processing and cut into different lengths. This reduces costs.

[0033] The present invention aims to disclose the contact angle, roller characteristics and their parameter algorithms of the bearing. Therefore, the present invention does not limit the structure and size of the cage 5, and it is not limited to any structure made of any material that adapts to the characteristics of the present invention under the existing technology.

[0034] The design method of the asymmetric self-aligning roller bearing with equal-diameter and unequal-length rollers is as follows:

[0035] Generally, when designing a fan, a bearing installation space will be reserved, that is, the outer dimensions of the bearing are known: inner diameter d, outer diameter D, and total width B.

[0036] Step 1: Set the contact angle difference α c ;

[0037] Step 2: Initially determine the double-row width ratio m

[0038] m = B 1 : B 2

[0039] Therefore:

[0040]

[0041]

[0042] Step 3: Calculate the contact angle

[0043]

[0044]

[0045] Step 4: Calculate the contact angle difference α c and determine

[0046] α c = |α 1 - α 2 |

[0047] If the set value in Step 1 is not reached, adjust the value of m, and loop Steps 2 - 4 until it is reached;

[0048] Step 5: Calculate the maximum diameter Da of the roller

[0049] Da = K 1 (D - d)

[0050] Coefficient K 1 = 0.24 - 0.27, preferably 0.25;

[0051] Step 6: Calculate the length L of the roller 1 and L 2

[0052] L 1 = K 2 B 1

[0053] L 2 = K 2 B 2

[0054] Coefficient K 2 = 0.74 - 0.78, preferably 0.76;

[0055] Step 7: Calculate the ball diameter R of the outer raceway

[0056] R = 0.5D - K 3 (D - d)

[0057] Coefficient K 3 = 0.09 - 0.11, preferably 0.1;

[0058] Step 8: Determine the inner ring and cage dimensions according to the roller dimensions.

[0059] The above steps can be used to draw a flow chart Figure 3 As shown, the calculation is performed with the help of a programming tool.

[0060] For an embodiment of the aforementioned algorithm:

[0061] It is known that the inner diameter of a fan main shaft bearing is d = 600mm, the outer diameter is D = 870mm, and the total width is 300mm. According to the calculation program, the curve of the ratio m and the contact angle is calculated as follows Figure 4 As shown in the figure. The closer the M value is to 1, the smaller the difference in the contact angles of the two rows; when it is equal to 1, the contact angles are equal, and the difference is 0, which means it is a symmetrical bearing.

[0062] Solution 1: Assuming that the contact angle difference should be 2° based on the force condition of the fan main shaft, the calculation method of the present invention is as follows:

[0063] Ratio m = 0.838

[0064]

[0065] The above scheme draws the engineering drawing as follows Figure 5 shown.

[0066] It can be seen that through the above design method, the contact angle and roller size parameters can be determined, and the dimensions of the internal parts of the bearing have been basically determined. Other design parameters can be further designed through the parameters calculated by the present invention.

[0067] At the same time, the same diameter and spherical radius of the double-row rollers make manufacturing simpler, and the same specifications of initial materials can be selected, based on the same process, reducing manufacturing costs.

[0068] The technology disclosed by the present invention in the field of asymmetric spherical roller bearings has obvious advancement and operability.

[0069] The parts not described in detail in this embodiment are prior art.

[0070] It should be noted that although the present invention is described by the above embodiments, the present invention may also have other various embodiments. Without departing from the spirit and scope of the present invention, it is obvious that those skilled in the art may make various corresponding changes and deformations to the present invention, but these changes and deformations should all fall within the scope of protection of the appended claims of the present invention and their equivalents.

Claims

1. Design method of an asymmetric self-aligning roller bearing for a fan, Characterized in that: The self-aligning roller bearing is composed of an outer ring, an inner ring, spherical rollers in row A, spherical rollers in row B, and a cage. Among them, the spherical rollers in row A are short spherical rollers, and the spherical rollers in row B are long spherical rollers. The long spherical rollers and the short spherical rollers have the same maximum diameter Da, the same spherical radius Ra, and different contact angles. The contact angle width of the spherical rollers in row A is set as B 1 , and the contact angle width of the spherical rollers in row B is B 2 . The raceway of the outer ring is a spherical arc with a continuous radius value R, and its center of the sphere O is at the demarcation point of the width B 1 and B 2 of the bearing center line; The design method of the asymmetric self-aligning roller bearing for a fan includes the following steps: S1. Set the contact angle difference α according to the known external dimensions of the bearing: inner diameter d, outer diameter D, and total width B c ; S2. Initially determine the double-column width ratio m, and obtain the contact angle width of the spherical rollers in column A as The contact angle width of the spherical rollers in column B is S3. Obtain the contact angle according to the conditions of step S2; S4. Calculate the contact angle difference α c And determine α c = |α 1 - α 2 |. If the set value in step S1 is not reached, adjust the value of m, and loop steps S2 - S3 until it is reached; S5. Calculate the maximum diameter Da of the spherical roller, the roller length L 1 and L 1 = K 2 B 1 and L 2 = K 2 B 2 and R = 0.5D - K 3 (D - d), where the coefficients K 1 and L 2 and the outer raceway ball diameter R, where the coefficient K 1 = 0.24 - 0.27, K 2 = 0.74 - 0.78, K 3 = 0.09 - 0.11; S6. Determine the sizes of the inner ring and the cage according to the sizes of the rollers.

2. The design method of an asymmetric self-aligning roller bearing for a fan according to claim 1, Characterized in that: In step S3: where the contact angle of the spherical rollers in column A and the contact angle of the spherical rollers in column B

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