A method for improving load sharing of a closed differential planetary gear train

Abstract

The application relates to a method for improving the load sharing of a closed differential planetary gear train of a coaxial dual-rotor helicopter speed reducer, which comprises a fixed-axle planetary gear train assembling method, design points, a star wheel tooth surface coordinate point acquisition method, a measurement data processing method, a tooth profile curve drawing method using the measurement data, a star wheel angular error measurement method and the like. Through the method, the load sharing index can be quantified, and reasonable quantification indexes can be achieved through installation adjustment, so that the assembling quality of the closed differential planetary gear train and the speed reducer assembled with the same is ensured, the assembling efficiency of the closed differential planetary gear train is improved, excessive vibration and other problems in the working process are avoided, and the reliability of the speed reducer is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for improving the load sharing of a planetary gear train, in particular a method for improving the load sharing of a closed differential planetary gear train applied to a closed planetary gear of a coaxial dual-rotor helicopter reducer. BACKGROUND

[0002] A coaxial dual-rotor helicopter reducer realizes the transmission of coaxial and opposite torques through a closed planetary gear. This structure can realize the transmission of large torque while the space size and weight can be controlled within a small range. The closed planetary gear transmission is composed of a first-stage fixed-axis planetary gear transmission and a first-stage differential planetary gear transmission. The load distribution among the planetary gears directly relates to the stability of the planetary gear train and affects the vibration level of the planetary gear transmission.

[0003] For a planetary gear transmission, if the load distribution among the planetary gears is uniform, the structure is more compact and the carrying capacity is greater as the number of planetary gears increases. In fact, due to the inevitable manufacturing and installation errors, as well as the deformation of components and other factors, the load distribution among the planetary gears is not uniform. Sometimes the load may be concentrated on a certain planetary gear, while the other (n-1) planetary gears are idle and cannot play a role in transmitting power. Therefore, it is very important to solve the problem of uneven load distribution among the planetary gears in order to fully exert the superiority of the planetary gear transmission and avoid abnormal operation or failure of the reducer.

[0004] The so-called uniform load distribution (or load balancing) among the planetary gears means that the meshing forces transmitted by the center gear to the planetary gears are equal, i.e. under the ideal conditions of manufacturing accuracy and stiffness, the teeth of the center gear and the teeth of the n planetary gears are in contact (meshing) at the same time, the resultant force of the normal forces of the planetary gears acting on the center gear is zero, and the center gear can transmit torque without radial load. However, in the absence of any load sharing measures, the load distribution among the planetary gears is actually not uniform, mainly due to various manufacturing errors of the gears, manufacturing and installation errors of the bearings, planetary carriers and housings, etc. The manufacturing errors of the planetary gear transmission parts will form gaps or interference between the working tooth profiles, and the ultimate goal of improving load sharing is to ensure that the sun gear / center gear and each planet gear are in meshing at the same time, and to eliminate the gaps or interference between the working tooth profiles.

[0005] The prior art measures and methods for improving load sharing mainly include: using floating basic components, using thin-walled components, controlling the machining precision of the housing mounting hole, etc., which have certain effects on realizing load sharing. The above methods mainly reflect in the design and machining aspects, cannot be applied to the actual engineering assembly of the planetary gear, and there is no reliable assembly and measurement method for guiding the actual engineering assembly, which cannot guarantee the load sharing of the closed differential planetary gear train in the actual assembly. Therefore, it is necessary to study an assembly and measurement method for improving the load sharing of the closed differential planetary gear train. SUMMARY

[0006] The technical problem solved by the present application is to provide a method for improving the load sharing of a closed differential planetary gear train, which includes assembly, adjustment, measurement, data processing, etc., so that the load sharing index can be quantified, and reasonable quantified index can be achieved through installation adjustment, so as to guarantee the assembly quality of the closed differential planetary gear train and the reducer assembled thereon, improve the assembly efficiency of the closed differential planetary gear train, avoid excessive vibration and other problems in the working process, and guarantee the reliability of the reducer.

[0007] The technical scheme of the present application is as follows:

[0008] A method for improving the load sharing of a closed differential planetary gear train, comprising the following steps:

[0009] Step 1: Assemble the fixed shaft planetary gear transmission assembly, measure the maximum runout of each sun gear shaft in the fixed shaft planetary gear transmission assembly, and mark the tooth end face at the maximum runout position of each sun gear shaft;

[0010] Step 2: Select and assemble adjustment pads to the fixed shaft planetary gear transmission assembly;

[0011] Step 3: Install the fixed shaft planetary gear transmission assembly to the housing;

[0012] Step 4: Rotate the sun gear shaft assembly and adjust the angular position, so that the tooth marks of each sun gear point to the same direction, and check whether the marks of each sun gear are in the same direction, if yes, execute step 5, otherwise, readjust the angular position of each sun gear;

[0013] Step 5: Install the central gear to the housing, so that the central gear meshes with each sun gear in the fixed shaft planetary gear transmission assembly;

[0014] Step 6: Rotate the central gear and measure the meshing tooth gap between the central gear and each sun gear in the fixed shaft planetary gear transmission assembly;

[0015] Step 7: Insert a plug gauge with a thickness corresponding to the meshing tooth gap into the non-working surface position of each sun gear, so that the working surface of each sun gear and the working surface of the central gear simultaneously mesh;

[0016] Step 8: scan each pinion tooth surface coordinate point and process the scanning data;

[0017] Step 9: draw the tooth profile curve using the scanning data, check whether the tooth profile is correct, if yes, execute Step 10, if no, re-execute Steps 8-9;

[0018] Step 10: calculate the angular error of the star wheel, if the angular error of the star wheel is less than a specified value, the angular error of the star wheel is qualified, and the angular error of the star wheel is recorded, if the angular error of the star wheel is greater than the specified value, re-execute Steps 2-10.

[0019] Further, for the fixed shaft planetary gear train adopting two-stage star wheel transmission, the method comprises the following steps:

[0020] Step 1: assemble the large star wheel and the small star wheel in the fixed shaft planetary gear transmission assembly, measure the maximum runout of the large star wheel shaft and the small star wheel shaft in the fixed shaft planetary gear transmission assembly, and mark the tooth end face at the maximum runout position of each star wheel shaft;

[0021] Step 2: after the large star wheel and the small star wheel are assembled together to form a star wheel shaft assembly, check the mark positions of the maximum runout positions of the large star wheel and the small star wheel, if the mark positions of the maximum runout positions of the large star wheel and the small star wheel are in the 180° direction, execute Step 3, otherwise, re-execute Steps 1-2;

[0022] Step 3: select and assemble an adjusting pad to the fixed shaft planetary gear transmission assembly;

[0023] Step 4: install the fixed shaft planetary gear transmission assembly to the casing;

[0024] Step 5: rotate the star wheel shaft assembly, adjust the angular position, make the tooth marked by the large star wheel point to the same direction, check whether the marks of each large star wheel are in the same direction, if yes, execute Step 6, otherwise, re-adjust the angular position of each large star wheel;

[0025] Step 6: install the central gear to the casing, make the central gear mesh with each large star wheel in the fixed shaft planetary gear transmission assembly;

[0026] Step 7: rotate the central gear, measure the meshing tooth gap between the central gear and each large star wheel in the fixed shaft planetary gear transmission assembly;

[0027] Step 8: insert a feeler gauge with a thickness corresponding to the meshing tooth gap into the non-working surface position of each large star wheel, so that the working surface of each large star wheel and the working surface of the central gear are simultaneously meshed;

[0028] Step 9: scan each pinion tooth surface coordinate point and process the scanning data;

[0029] Step 10: draw the tooth profile curve using the scanning data to check if the tooth profile is correct, if yes, execute step 11, if no, re-execute steps 9-10;

[0030] Step 11: calculate the angular error of the small star wheel, if the angular error of the small star wheel is less than a specified value, the angular error of the small star wheel is qualified, and the angular error of the small star wheel is recorded; if the angular error of the small star wheel is greater than the specified value, re-execute steps 3-11.

[0031] Further, for the fixed shaft planetary gear train adopting single-stage star wheel transmission, the method comprises the following steps:

[0032] Step 1: assemble the single-stage star wheel in the fixed shaft planetary gear transmission assembly, measure the maximum runout of each single-stage star wheel shaft in the fixed shaft planetary gear transmission assembly, and mark the tooth end face at the maximum runout position of each single-stage star wheel;

[0033] Step 2: select and assemble the adjusting pad to the fixed shaft planetary gear transmission assembly;

[0034] Step 3: install the fixed shaft planetary gear transmission assembly to the case;

[0035] Step 4: rotate the star wheel shaft assembly to adjust the angular position, so that the marked teeth of each single-stage star wheel point to the same direction, check if the marks of each single-stage star wheel are in the same direction, if yes, execute step 5, otherwise, re-adjust the angular position of each single-stage star wheel;

[0036] Step 5: install the central gear to the case, so that the central gear meshes with each single-stage star wheel in the fixed shaft planetary gear transmission assembly;

[0037] Step 6: rotate the central gear to measure the meshing tooth gap between the central gear and each single-stage star wheel in the fixed shaft planetary gear transmission assembly;

[0038] Step 7: insert a feeler gauge with a thickness corresponding to the meshing tooth gap into the non-working surface position of each single-stage star wheel, so that the working surface of each single-stage star wheel and the working surface of the central gear are simultaneously meshed;

[0039] Step 8: scan the coordinate points of the tooth surface of each single-stage star wheel, and process the scanning data;

[0040] Step 9: draw the tooth profile curve using the scanning data to check if the tooth profile is correct, if yes, execute step 10, if no, re-execute steps 8-9;

[0041] Step 10: calculate the angular error of the single-stage star wheel, if the angular error of the single-stage star wheel is less than a specified value, the angular error of the single-stage star wheel is qualified, and the angular error of the single-stage star wheel is recorded; if the angular error of the single-stage star wheel is greater than the specified value, re-execute steps 2-10.

[0042] Further, for the fixed shaft planetary gear train with two-stage star wheel transmission, the maximum runout of each large and small star wheel shaft in the fixed shaft planetary transmission is measured and recorded by using a dial gauge and a three-coordinate measuring instrument, taking the bearing fitting support point or the finished surface of the star wheel shaft as the reference; for the fixed shaft planetary gear train with single-stage star wheel transmission, the maximum runout of each single-stage star wheel shaft in the fixed shaft planetary transmission is measured and recorded by using a dial gauge and a three-coordinate measuring instrument, taking the bearing fitting support point or the finished surface of the star wheel shaft as the reference.

[0043] Further, when adjusting the angular position, the marked teeth of each large star wheel are simultaneously directed to the outside or inside of the casing, and are evenly distributed in the angular direction; when adjusting the angular position, the marked teeth of each single-stage star wheel are simultaneously directed to the outside or inside of the casing, and are evenly distributed in the angular direction.

[0044] Further, when measuring and recording the maximum runout of each star wheel shaft in the fixed shaft planetary transmission, the position tolerance of the installation hole of the dial gauge and the three-coordinate measuring instrument matched with each star wheel shaft assembly is not more than φ0.2, taking the central gear stop or the finished surface as the reference; each installation hole is an interference fit.

[0045] Further, for the fixed shaft planetary gear train with two-stage star wheel transmission, the measuring equipment for scanning the tooth surface coordinate points of the small star wheel at least includes a three-coordinate measuring instrument, the tooth surface coordinate points of the outermost three or more adjacent teeth at the same cross-sectional position of each small star wheel are scanned, and the probe is avoided from interfering with the part during the measurement; the extension name of the generated measurement data at least includes.DAT; for the fixed shaft planetary gear train with single-stage star wheel transmission, the measuring equipment for scanning the tooth surface coordinate points of the single-stage star wheel at least includes a three-coordinate measuring instrument; the tooth surface coordinate points of the outermost three or more adjacent teeth at the same cross-sectional position of each single-stage star wheel are scanned, and the probe is avoided from interfering with the part during the measurement; the extension name of the generated measurement data at least includes.DAT.

[0046] Further, for the fixed shaft planetary gear train with two-stage star wheel transmission, the small star wheel tooth surface coordinate point data is processed into two-dimensional coordinate points by using Excel software, then the two-dimensional coordinate point (x, y) data column in the Excel table is copied in whole, the straight line or multi-segment line command is selected in the CAD software, the coordinate point data is pasted, and the tooth profile curve is formed in the CAD interface; for the fixed shaft planetary gear train with single-stage star wheel transmission, the single-stage star wheel tooth surface coordinate point data is processed into two-dimensional coordinate points by using Excel software, then the two-dimensional coordinate point (x, y) data column in the Excel table is copied in whole, the straight line or multi-segment line command is selected in the CAD software, the coordinate point data is pasted, and the tooth profile curve is formed in the CAD interface.

[0047] Further, for the fixed shaft planetary gear train adopting two-stage star wheel transmission, the drawing software for measuring the angular error of the small star wheel at least includes CAD software, and when the angular error of the small star wheel is drawn and measured, a point on the outermost tooth working surface of one small star wheel near the division circle part is taken as a reference, the theoretical points of other small star wheels are obtained by adopting the circular array, and the distance between the actual point and the theoretical point on the same diameter is measured, that is, the angular error of the small star wheel; for the fixed shaft planetary gear train adopting single-stage star wheel transmission, the drawing software for measuring the angular error of the single-stage star wheel at least includes CAD software, and when the angular error of the single-stage star wheel is drawn and measured, a point on the outermost tooth working surface of one single-stage star wheel near the division circle part is taken as a reference, the theoretical points of other single-stage star wheels are obtained by adopting the circular array, and the distance between the actual point and the theoretical point on the same diameter is measured, that is, the angular error of the single-stage star wheel.

[0048] The present application has the following beneficial effects:

[0049] The present application provides a specific method for improving the load sharing of the closed differential planetary gear train, including the assembly method of the fixed shaft planetary gear train, the design points, the coordinate point acquisition method of the star wheel tooth surface, the measurement data processing method, the tooth profile curve drawing method using the measurement data, the star wheel angular error measurement method, etc. Through the method provided by the present application, the load sharing index can be quantified, and the reasonable quantified index can be achieved through installation adjustment, so as to ensure the assembly quality of the closed differential planetary gear train and the reducer, improve the assembly efficiency of the closed differential planetary gear train, avoid excessive vibration and other problems in the working process, and ensure the reliability of the reducer. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a schematic diagram of the fixed shaft planetary gear train;

[0051] Figure 2 It is a schematic diagram of the differential planetary gear train;

[0052] Figure 3 It is a flow chart of the method for improving the load sharing of the closed differential planetary gear train in the first embodiment;

[0053] Figure 4 It is a schematic diagram of the selected adjustment pad;

[0054] In the figure, 1 is the sun gear, 2 is the central gear, 3 is the gear chain case cover, 4 is the fixed shaft transmission gear ring, 5 is the small star wheel, 6 is the large star wheel, 7 is the gear chain case, 8 is the spline flange, 9 is the planetary transmission gear ring, 10 is the planetary gear, 11 is the bearing cover, 12 is the ball bearing, 13 is the lower adjustment pad, 14 is the upper adjustment pad, and 15 is the thrust washer. DETAILED DESCRIPTION

[0055] The specific embodiments of the present application, such as the shape, structure, mutual position and connection relationship between the parts, the function and working principle of the parts, the manufacturing process and the operation and use method, are further described below with reference to the drawings and the embodiments, so as to help the skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present application:

[0056] A certain coaxial dual-rotor helicopter speed reducer realizes coaxial reverse torque transmission through closed planetary gear transmission. The closed planetary gear transmission is composed of a first fixed-axle planetary gear transmission and a first differential planetary gear transmission. The fixed-axle planetary gear train is a split-torque transmission structure, as shown in Figure 1 , the central gear 1 drives five large star wheels (helical cylindrical gears), the five large star wheels 6 are connected with five small star wheels 5 (spur cylindrical gears) through splines, the small star wheels 5 are engaged with the fixed-axle transmission gear ring 4, and the large and small star wheels 5 are combined, which is beneficial to the selection of the number of teeth between the gears and the matching of the transmission ratio. The differential planetary gear train adopts spur cylindrical gear transmission, as shown in Figure 2 , the sun gear 1 is engaged with six planetary gears 10, the planetary gears 10 are engaged with the planetary transmission gear ring 9, and the planetary transmission gear ring 9 is connected with the fixed-axle transmission gear ring 4 through a spline torque transmission disc, so that the output rotational speed of the gear ring is consistent with the output rotational speed of the planetary carrier, and the directions are opposite. The present application mainly aims at the assembly method of the first fixed-axle planetary gear transmission system, the design points, the star wheel tooth surface coordinate point acquisition method, the measurement data processing method, the method of drawing tooth profile curves by using measurement data, and the star wheel angular error measurement method to improve the load sharing of the entire closed differential planetary gear.

[0057] The method for improving the load sharing of the closed differential planetary gear train of the present application comprises the following steps:

[0058] Step 1: Assemble the fixed-axle planetary gear transmission assembly, measure the maximum runout of each star wheel shaft in the fixed-axle planetary gear transmission assembly, and mark the tooth end face at the maximum runout position of each star wheel shaft;

[0059] Step 2: Select and assemble adjustment pads to the fixed-axle planetary gear transmission assembly;

[0060] Step 3: Install the fixed-axle planetary gear transmission assembly to the case;

[0061] Step 4: Rotate the star wheel shaft assembly, adjust the angular position, make the tooth marks of each star wheel point in the same direction, check whether the marks of each star wheel are in the same direction, if yes, execute step 5, otherwise, readjust the angular position of each star wheel;

[0062] Step 5: Install the central gear 2 to the case, so that the central gear 2 is engaged with each star wheel in the fixed-axle planetary gear transmission assembly;

[0063] Step 6: Turn the central gear 2, and measure the meshing tooth gap of each star wheel in the fixed shaft planetary gear transmission assembly;

[0064] Step 7: Insert a feeler gauge with a thickness corresponding to the meshing tooth gap into the non-working surface of each star wheel, so that the working surface of each star wheel is simultaneously meshed with the working surface of the central gear;

[0065] Step 8: Scan the coordinate points of the tooth surface of each star wheel, and process the scanning data;

[0066] Step 9: Draw the tooth profile curve using the scanning data, and check whether the tooth profile is correct. If yes, execute Step 10; if no, re-execute Steps 8-9.

[0067] Step 10: Calculate the angular error of the star wheel. If the angular error of the star wheel is less than a specified value, the angular error of the star wheel is qualified, and the angular error of the star wheel is recorded. If the angular error of the star wheel is greater than the specified value, re-execute Steps 2-10.

[0068] One embodiment of the present application is that, for the fixed shaft planetary gear train adopting two-stage star wheel transmission, the method comprises the following steps:

[0069] Step 1: Assemble the large star wheel 6 and the small star wheel 5 in the fixed shaft planetary gear transmission assembly. Take the star wheel shaft bearing fitting fulcrum or the finished surface as the reference, measure the maximum runout of the large star wheel 6 shaft and the small star wheel 5 shaft in the fixed shaft planetary gear transmission assembly by using a dial gauge and a three-coordinate measuring instrument, and mark the tooth end surface at the maximum runout position of each star wheel shaft. The specific implementation is as follows: In order to reduce the runout error of the combined large and small star wheels 5 and ensure the stability of the star wheel shaft assembly in operation, measure the runout at the index circle of the large and small star wheels 5 in the part state respectively, and mark "*" at the maximum runout point respectively. When measuring and recording the maximum runout of each star wheel shaft in the fixed shaft planetary transmission, take the central gear 2 stop or the finished surface as the reference, and the position degree of the installation hole of the dial gauge and the three-coordinate measuring instrument matched with each star wheel shaft assembly is not more than φ0.2. Each installation hole is an interference fit.

[0070] Step 2: After assembling the large and small star wheels 5 to form a star wheel shaft assembly, check the mark position of the maximum runout position of the large and small star wheels 5. If the mark position of the maximum runout position of the large and small star wheels 5 is in the 180° direction, execute Step 3; otherwise, re-execute Steps 1-2. The number of teeth of the large star wheel is 51, the number of teeth of the small star wheel 5 is 17, and the number of teeth of the large star wheel 6 is exactly 3 times the number of teeth of the small star wheel. When assembling the star wheel shaft assembly, the teeth marked with "*" of the large and small star wheels 5 are installed in the 180° direction, so as to reduce the runout error after combination, and help to improve the load sharing.

[0071] Step 3: Select and assemble the adjusting pad to the fixed shaft planetary gear transmission assembly;

[0072] The adjusting pad includes an upper adjusting pad 14 and a lower adjusting pad 13. The thickness of the upper adjusting pad 14 is calculated according to the following formula:

[0073] The thickness of the upper adjusting pad 14 is calculated as D = A + B + C - X - 38

[0074] Wherein A is the dimension from the gear case end face to the bearing housing end face;

[0075] B is the thickness of the thrust washer;

[0076] C is the protrusion of the inner ring relative to the outer ring of the bearing. If the bearing specification indicates that the inner ring is "concave", it is negative;

[0077] X is the thickness correction of the adjusting pad, X = 3.08△, and △ is the calculated value of the side gap.

[0078] The thickness of the lower adjusting pad 13 is calculated according to the following formula:

[0079] H = E - F + (0.01 - 0.03)

[0080] Wherein E is the dimension from the gear case end face to the bearing cover end face;

[0081] F is the dimension of the corresponding position of the bearing cover 11.

[0082] After the thickness of the upper and lower adjusting pads is calculated, upper and lower adjusting pads of the same size are produced according to the calculated values, and are installed on the two end faces of the ball bearing between the star wheel shaft assembly and the gear case, and are tightly fitted with the two end faces of the ball bearing.

[0083] Step 4: Install the fixed shaft planetary gear transmission assembly to the gear case;

[0084] Step 5: Rotate the star wheel shaft assembly to adjust the angular position. When adjusting the angular position, the marked teeth of each large star wheel 6 are simultaneously pointed to the outside or inside of the gear case, and the angular position is uniformly distributed. Check whether the marks of each large star wheel 6 are in the same direction. If yes, proceed to Step 6, otherwise, readjust the angular position of each large star wheel 6.

[0085] Step 6: Install the central gear 2 to the gear case so that the central gear 2 meshes with each large star wheel 6 in the fixed shaft planetary gear transmission assembly. Install the central gear 2 to the gear case assembly. Three workers cooperate to prevent the angular position of the large star wheel 6 from changing after the central gear 2 is installed. After the central gear 2 is installed, check again whether the angular position of the large star wheel 6 is correct.

[0086] Step 7: Turn the central gear 2, and measure the meshing tooth gap between the central gear 2 and each large star gear 6 in the fixed-axle planetary gear transmission assembly;

[0087] Step 8: Insert a feeler gauge with a thickness corresponding to the meshing tooth gap into the non-working surface of each large star gear 6, so that the working surface of each large star gear 6 is simultaneously meshed with the working surface of the central gear 2;

[0088] Step 9: Scan the coordinate points of the tooth surface of each small star gear 5, and process the scanned data; the measuring equipment used for scanning the coordinate points of the tooth surface of the small star gear 5 at least includes a three-coordinate measuring instrument, and the coordinate points of the tooth surface of three or more adjacent teeth on the outermost side of each small star gear 5 at the same cross-sectional position are scanned, and the measuring process avoids interference between the measuring head and the part; the measurement data formed at least include the extension name.DAT; the coordinate point data of the tooth surface of the small star gear 5 is processed into two-dimensional coordinate points using Excel software, then the two-dimensional coordinate point (x, y) data column in the Excel table is copied in its entirety, the straight line or multi-segment line command is selected in the CAD software, and the coordinate point data is pasted, and the tooth profile curve is formed in the CAD interface;

[0089] Step 10: Draw the tooth profile curve using the scanned data, and check whether the tooth profile is correct; if yes, execute Step 11; if no, re-execute Steps 9-10;

[0090] Step 11: Calculate the angular error of the small star gear 5; if the angular error of the small star gear 5 is less than a specified value, the angular error of the small star gear 5 is qualified, the angular error of the small star gear 5 is recorded, and the error is guaranteed within the specified value range, which indicates that the above steps have improved the load sharing property of the closed differential planetary gear train; if the angular error of the small star gear 5 is greater than the specified value, re-execute Steps 3-11 until the error is less than the specified value, and the load sharing property is improved.

[0091] The drawing software for measuring the angular error of the small star gear 5 at least includes CAD software; when drawing and measuring the angular error of the small star gear 5, one point on the outermost tooth working surface of one small star gear 5 close to the division circle part is taken as a reference, the theoretical points of each small star gear 5 are obtained by taking a circumferential array, and the distance between the actual point and the theoretical point on the same diameter is the angular error of the small star gear;

[0092] The second embodiment of the present application is that for the fixed-axle planetary gear train adopting single-stage star wheel transmission, the method comprises the following steps:

[0093] Step 1: Assemble single-stage star wheel in fixed-axle planetary gear transmission assembly, and measure and record maximum runout of each single-stage star wheel shaft in fixed-axle planetary transmission using a dial gauge and a three-coordinate measuring instrument, with the star wheel shaft bearing fitting fulcrum or finish surface as the reference, and mark the tooth end face at the maximum runout position of each single-stage star wheel; the specific implementation is as follows: in order to reduce the runout error of each single-stage star wheel assembly and ensure the stability of the single-stage star wheel shaft assembly, measure the runout at the index circle of each single-stage star wheel in the part state, and mark "*" at the maximum runout point; when measuring and recording the maximum runout of each star wheel shaft in the fixed-axle planetary transmission, use the central gear stop or finish surface as the reference, and the position tolerance of the installation hole of the dial gauge and the three-coordinate measuring instrument matched with each star wheel shaft assembly is not more than φ0.2; each installation hole is an interference fit;

[0094] Step 2: Select and assemble adjustment pads to the fixed-axle planetary gear transmission assembly;

[0095] The adjustment pads include upper adjustment pads 14 and lower adjustment pads 13, and the thickness of the upper adjustment pads 14 is calculated according to the following formula:

[0096] The thickness of the upper adjustment pad 14 is calculated as D = A + B + C - X - 38

[0097] In the formula, A is the size from the gear chain case end face to the bearing seat end face;

[0098] B is the thickness of the thrust washer;

[0099] C is the protrusion of the bearing inner ring relative to the outer ring, and if the bearing measurement standard indicates that the inner ring is "concave", it is negative;

[0100] X is the thickness correction amount of the adjustment pad, X = 3.08△, and△ is the calculated value of the side gap.

[0101] The thickness of the lower adjustment pad 13 is calculated according to the following formula:

[0102] H = E - F + (0.01 - 0.03)

[0103] In the formula, E is the size from the gear chain case end face to the bearing cover end face;

[0104] F is the size of the corresponding position of the bearing cover 11.

[0105] After the thickness of the upper and lower adjustment pads is calculated, upper and lower adjustment pads with the same size are produced according to the calculated value, and the upper and lower adjustment pads are installed on the two end faces of the ball bearing between the star wheel shaft assembly and the gear chain case, and tightly fit the two end faces of the ball bearing.

[0106] Step 3: Install the fixed-axle planetary gear transmission assembly to the case;

[0107] Step 4: Turn the star wheel shaft assembly to adjust the angular position, mark the teeth of each single-stage star wheel at the same time pointing to the outside or inside of the casing when adjusting the angular position, and check whether the marks of each single-stage star wheel are in the same direction. If yes, execute Step 5; otherwise, readjust the angular position of each single-stage star wheel.

[0108] Step 5: Install the central gear on the casing so that the central gear meshes with each single-stage star wheel in the fixed shaft planetary gear transmission assembly.

[0109] Step 6: Turn the central gear 2 and measure the meshing tooth gap between the central gear 2 and each single-stage star wheel in the fixed shaft planetary gear transmission assembly.

[0110] Step 7: Insert a feeler gauge with a thickness corresponding to the meshing tooth gap into the non-working surface position of each single-stage star wheel so that the working surface of each single-stage star wheel simultaneously meshes with the working surface of the central gear.

[0111] Step 8: Scan the tooth surface coordinate points of each single-stage star wheel and process the scanned data. The measuring equipment used for scanning the tooth surface coordinate points of the single-stage star wheel at least includes a three-coordinate measuring instrument. The tooth surface coordinate points of the outermost three or more adjacent teeth at the same cross-sectional position of each single-stage star wheel are scanned, and the measuring process avoids interference between the measuring head and the part. The measurement data formed at least include the extension name.DAT. The tooth surface coordinate point data of the single-stage star wheel is processed into two-dimensional coordinate points using Excel software, then the two-dimensional coordinate point (x, y) data column in the Excel table is copied in its entirety, the straight line or multi-segment line command is selected in the CAD software, and the coordinate point data is pasted, thereby forming a tooth profile curve in the CAD interface.

[0112] Step 9: Draw the tooth profile curve using the scanned data to check whether the tooth profile is correct. If yes, execute Step 10; otherwise, re-execute Steps 8-9.

[0113] Step 10: Calculate the angular error of the single-stage star wheel. If the angular error of the single-stage star wheel is less than a specified value, the angular error of the single-stage star wheel is qualified, the angular error of the single-stage star wheel is recorded, and the error is guaranteed within the specified value range, indicating that the above steps have improved the load sharing of the closed differential planetary gear train. If the angular error of the single-stage star wheel is greater than the specified value, re-execute Steps 2-10 until the error is less than the specified value, and the load sharing is improved. The drawing software for measuring the angular error of the single-stage star wheel at least includes CAD software. When measuring the angular error of the single-stage star wheel, a point near the division circle position on the working surface of the outermost tooth of one single-stage star wheel is taken as a reference, a circular array is adopted to obtain the theoretical points of each single-stage star wheel, and the distance between the actual points and the theoretical points on the same diameter is the angular error of the single-stage star wheel.

[0114] The application provides a specific method for improving load sharing of a closed differential planetary gear train, which comprises a fixed-axle planetary gear train assembling method, design points, a star wheel tooth surface coordinate point acquisition method, a measurement data processing method, a tooth profile curve drawing method using the measurement data, a star wheel angular error measurement method and the like. The method provided by the application can quantize the load sharing index, and can reach a reasonable quantized index through installation adjustment, so as to ensure the assembling quality of the closed differential planetary gear train and a reducer equipped with the same, improve the assembling efficiency of the closed differential planetary gear train, avoid excessive vibration and other problems in the working process, and ensure the reliability of the reducer.

[0115] The application is described above in connection with the drawings, and it is obvious that the specific implementation of the application is not limited by the above method, as long as various non-essential improvements are made by using the method concept and technical solution of the application, or the concept and technical solution of the application is directly applied to other occasions without improvement, which is within the protection scope of the application.

Claims

1. A method of improving load sharing in a closed differential planetary gear train, characterized by, Includes the following steps: Step 1: Assemble the fixed-axis planetary gear transmission assembly, measure the maximum runout of each planetary gear shaft in the fixed-axis planetary gear transmission assembly, and mark the tooth end face of the maximum runout part of each planetary gear shaft; Step 2: Select and install the adjusting shim onto the fixed-axis planetary gear transmission assembly; Step 3: Install the fixed-axis planetary gear transmission assembly onto the housing; Step 4: Rotate the star wheel shaft assembly and adjust the angular position so that the marked teeth of each star wheel point in the same direction. Check whether the marks of each star wheel are in the same direction. If they are, proceed to step 5; otherwise, readjust the angular position of each star wheel. Step 5: Install the central gear onto the housing, so that the central gear meshes with each planetary gear in the fixed-axis planetary gear transmission assembly; Step 6: Rotate the central gear and measure the meshing backlash between the central gear and each planetary gear in the fixed-axis planetary gear transmission assembly; Step 7: Insert a feeler gauge with a thickness equivalent to the meshing tooth clearance into the non-working surface of each star wheel, so that the working surface of each star wheel meshes with the working surface of the central gear simultaneously; Step 8: Scan the coordinates of each star wheel tooth surface and process the scanned data; Step 9: Use the scan data to draw the tooth profile curve and check if the tooth profile is correct. If it is, proceed to step 10; otherwise, repeat steps 8 and 9. Step 10: Calculate the star wheel angular error. If the star wheel angular error is less than the specified value, the star wheel angular error is qualified and the star wheel angular error is recorded. If the star wheel angular error is greater than the specified value, repeat steps 2 to 10.

2. A method of improving load sharing in a closed differential planetary gear set according to claim 1, characterized in that, For a fixed-axis planetary gear train employing a two-stage star gear transmission, the method includes the following steps: Step 1: Assemble the large and small planetary gears in the fixed-axis planetary gear transmission assembly, measure the maximum runout of the large and small planetary gear shafts in the fixed-axis planetary gear transmission assembly, and mark the tooth end face of the maximum runout location of each planetary gear shaft; Step 2: After assembling the large and small star wheels together to form the star wheel shaft assembly, check the marked position of the maximum runout of the large and small star wheels. If the marked position of the maximum runout of the large and small star wheels is in the 180° direction, proceed to step 3; otherwise, repeat steps 1 to 2. Step 3: Select and install the adjusting shim onto the fixed-axis planetary gear transmission assembly; Step 4: Install the fixed-axis planetary gear transmission assembly onto the housing; Step 5: Rotate the star wheel shaft assembly and adjust the angular position so that the marked teeth of the large star wheels point in the same direction. Check whether the marks of each large star wheel are in the same direction. If they are, proceed to step 6; otherwise, readjust the angular position of each large star wheel. Step 6: Install the central gear onto the housing, so that the central gear meshes with each of the large planetary gears in the fixed-axis planetary gear transmission assembly; Step 7: Rotate the central gear and measure the meshing backlash between the central gear and each large planetary gear in the fixed-axis planetary gear transmission assembly; Step 8: Insert a feeler gauge with a thickness equivalent to the meshing tooth clearance into the non-working surface of each large star wheel, so that the working surface of each large star wheel meshes with the working surface of the central gear simultaneously; Step 9: Scan the coordinate points of each small star gear tooth surface and process the scan data; Step 10: Use the scan data to draw the tooth profile curve and check if the tooth profile is correct. If it is, proceed to step 11; otherwise, repeat steps 9 and 10. Step 11: Calculate the angular error of the small star wheel. If the angular error of the small star wheel is less than the specified value, the angular error of the small star wheel is qualified and the angular error of the small star wheel is recorded. If the angular error of the small star wheel is greater than the specified value, repeat steps 3 to 11.

3. A method of improving load sharing in a closed differential planetary gear set according to claim 2, characterized in that, For a fixed-axis planetary gear train employing a single-stage stellar gear drive, the method includes the following steps: Step 1: Assemble the single-stage star gears in the fixed-axis planetary gear transmission assembly, measure the maximum runout of each single-stage star gear shaft in the fixed-axis planetary gear transmission assembly, and mark the tooth end face of the maximum runout location of each single-stage star gear; Step 2: Select and install the adjusting shim onto the fixed-axis planetary gear transmission assembly; Step 3: Install the fixed-axis planetary gear transmission assembly onto the housing; Step 4: Rotate the star wheel shaft assembly and adjust the angular position so that the marked teeth of each single-stage star wheel point in the same direction. Check whether the marks of each single-stage star wheel are in the same direction. If they are, proceed to step 5; otherwise, readjust the angular position of each single-stage star wheel. Step 5: Install the central gear onto the housing, so that the central gear meshes with each single-stage planetary gear in the fixed-axis planetary gear transmission assembly; Step 6: Rotate the central gear and measure the meshing backlash between the central gear and each single-stage planetary gear in the fixed-axis planetary gear transmission assembly; Step 7: Insert a feeler gauge with a thickness equivalent to the meshing tooth clearance into the non-working surface of each single-stage star wheel, so that the working surface of each single-stage star wheel meshes with the working surface of the central gear simultaneously; Step 8: Scan the coordinate points of each single-stage star wheel tooth surface and process the scanned data; Step 9: Use the scan data to draw the tooth profile curve and check if the tooth profile is correct. If it is, proceed to step 10; otherwise, repeat steps 8 and 9. Step 10: Calculate the angular error of a single-stage star wheel. If the angular error of a single-stage star wheel is less than the specified value, then the angular error of the single-stage star wheel is qualified, and the angular error of the single-stage star wheel is recorded. If the angular error of a single-stage star wheel is greater than the specified value, repeat steps 2 to 10.

4. A method of improving load sharing in a closed differential planetary gear set according to claim 3, wherein, For a fixed-axis planetary gear train employing a two-stage star gear drive, the maximum runout of each large and small star gear shaft in the fixed-axis planetary transmission is measured and recorded using a dial indicator and a coordinate measuring instrument, with the star gear shaft bearing mating point or the finished surface as the reference. For a fixed-axis planetary gear train employing a single-stage star gear drive, the maximum runout of each single-stage star gear shaft in the fixed-axis planetary transmission is measured and recorded using a dial indicator and a coordinate measuring instrument, with the star gear shaft bearing mating point or the finished surface as the reference.

5. A method for improving the load-sharing performance of a closed differential planetary gear train according to claim 3, characterized in that, For a fixed-axis planetary gear system with two-stage star gear transmission, when adjusting the angular position, the marked teeth of each star gear should point to the outside or inside of the casing simultaneously, with the teeth evenly distributed in the angular direction. For a fixed-axis planetary gear system with single-stage star gear transmission, when adjusting the angular position, the marked teeth of each single-stage star gear should point to the outside or inside of the casing simultaneously, with the teeth evenly distributed in the angular direction.

6. A method for improving the load-sharing performance of a closed differential planetary gear train according to claim 4, characterized in that, When measuring and recording the maximum runout of each star wheel shaft in the fixed-axis planetary transmission using a dial indicator and a coordinate measuring instrument, with the central gear stop or the finished surface as the reference, the positional tolerance of the mounting holes of the dial indicator and the coordinate measuring instrument with each star wheel shaft assembly does not exceed φ0.2; each mounting hole is an interference fit.

7. A method for improving the load-sharing performance of a closed differential planetary gear train according to claim 3, characterized in that, For a fixed-axis planetary gear train employing a two-stage stellar gear drive, the measuring equipment used to scan the tooth surface coordinate points of the small stellar gears shall include at least a coordinate measuring machine (CMM). The CMM shall scan the tooth surface coordinate points of the three or more outermost adjacent teeth at the same cross-sectional position of each small stellar gear, avoiding interference between the probe and the workpiece during the measurement process. The resulting measurement data shall have a file extension of at least .DAT. For a fixed-axis planetary gear train employing a single-stage stellar gear drive, the measuring equipment used to scan the tooth surface coordinate points of the single-stage stellar gears shall include at least a coordinate measuring machine (CMM). The CMM shall scan the tooth surface coordinate points of the three or more outermost adjacent teeth at the same cross-sectional position of each single-stage stellar gear, avoiding interference between the probe and the workpiece during the measurement process. The resulting measurement data shall have a file extension of at least .DAT.

8. A method for improving the load-sharing performance of a closed differential planetary gear train according to claim 7, characterized in that, For a fixed-axis planetary gear train using a two-stage star gear drive, use Excel software to process the coordinate point data of the small star gear tooth surface into two-dimensional coordinate points. Then, copy the entire two-dimensional coordinate point (x, y) data column from the Excel sheet. In the CAD software, select the line or polyline command, paste the coordinate point data, and the tooth profile curve will be formed in the CAD interface. For a fixed-axis planetary gear train using a single-stage star gear drive, use Excel software to process the coordinate point data of the single-stage star gear tooth surface into two-dimensional coordinate points. Then, copy the entire two-dimensional coordinate point (x, y) data column from the Excel sheet. In the CAD software, select the line or polyline command, paste the coordinate point data, and the tooth profile curve will be formed in the CAD interface.

9. A method for improving the load-sharing performance of a closed differential planetary gear train according to claim 8, characterized in that, For a fixed-axis planetary gear train employing a two-stage star gear drive, the drawing software for measuring the angular error of the small star gears should at least include CAD software. When drawing and measuring the angular error of the small star gears, a point near the pitch circle on the outermost tooth working surface of one small star gear is used as a reference. A circular array is used to obtain the theoretical point of each other small star gear. The distance between the actual point and the theoretical point on the same diameter is the angular error of the small star gear. For a fixed-axis planetary gear train employing a single-stage star gear drive, the drawing software for measuring the angular error of the single-stage star gear should at least include CAD software. When drawing and measuring the angular error of the single-stage star gear, a point near the pitch circle on the outermost tooth working surface of one single-stage star gear is used as a reference. A circular array is used to obtain the theoretical point of each other single-stage star gear. The distance between the actual point and the theoretical point on the same diameter is the angular error of the single-stage star gear.

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