Helicopter transmission chain efficiency estimation method suitable for various configurations

Abstract

The invention relates to the field of helicopter transmission chain efficiency estimation, and discloses a helicopter transmission chain efficiency estimation method suitable for various configurations. And through calculation, an estimation result is quickly generated, and recalculation is not needed in the face of transmission systems of different configurations. Selecting a power loss calculation model used by each stage of transmission gear set based on a transmission mode of gears in each stage of gear set in a to-be-estimated helicopter transmission chain, performing calculation in combination with the power loss of a single group of gears to obtain the power loss of each stage of gear set, and performing further superposition to obtain the power loss of the helicopter transmission chain. And the transmission system efficiency is further obtained. Through calculation, an estimation result is quickly generated based on efficiency parameters such as gear types, transmission modes and gear parameters of gears at all levels of the helicopter transmission chain, the design period is shortened, the transmission chain efficiency calculation process is more systematic, the method can also be used in the subsequent helicopter transmission chain efficiency optimization process, and the design efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of helicopter drivetrain efficiency estimation, and in particular to a method for estimating the efficiency of helicopter drivetrains applicable to various configurations. Background Technology

[0002] Estimating the efficiency of the main drivetrain in a helicopter transmission system is of crucial theoretical value for overall energy optimization and performance improvement. As the core path of power transmission, the efficiency of the main drivetrain directly affects key indicators such as rotor power, fuel economy, and range. By constructing a multiphysics coupling model (covering gear meshing losses, aerodynamic drag, etc.), the power loss mechanism can be systematically analyzed, providing quantitative basis for lightweight transmission system design, material selection, and lubrication strategies. This, in turn, promotes the innovative development of high-power-density transmission technology and has significant engineering implications for the research and development of next-generation high-speed, heavy-load helicopters. Summary of the Invention

[0003] To address the above problems, this invention proposes a method for estimating the efficiency of helicopter transmission chains applicable to various configurations. Through calculation, the estimation results are generated quickly, and there is no need to recalculate when dealing with transmission systems of different configurations.

[0004] The technical solution of this invention is as follows: It is carried out according to the following steps:

[0005] Step 1: Collect helicopter transmission system configuration database and categorize the gear transmission methods in the helicopter transmission chain according to gear type; the gear transmission methods include bevel gear transmission, cylindrical gear transmission and planetary gear train transmission;

[0006] Step 2: Establish power loss calculation models for gear sets under different transmission methods according to the gear transmission method;

[0007] Step 3: Obtain the number of driving gears and driven gears in each stage of transmission;

[0008] Step 4: Establish a power loss calculation model for the gear set;

[0009] Step 5: Based on the transmission mode of the gears in each gear group of the helicopter transmission chain to be estimated, select the power loss calculation model used for each gear group of the transmission chain. Combine the power loss of a single gear group in Step 2 to calculate the power loss of each gear group. After further superposition, obtain the power loss of the helicopter transmission chain, and then obtain the transmission system efficiency.

[0010] The gear transmission methods mentioned in step 2 include bevel gear transmission, cylindrical gear transmission, and planetary gear train transmission;

[0011] The power loss of spur gears is calculated according to the Anderson and Loewenthal formula, including gear rolling power loss, gear sliding power loss and gear oil resistance (wind resistance) power loss;

[0012] The power loss calculation of planetary gear trains is based on the power loss calculation of spur gears. By applying a rotational speed equal to and opposite to the planet carrier speed to the entire planetary gear train, it is transformed into a virtual fixed-axis gear transmission system. In this equivalent system, the meshing power loss between the sun gear and planet gears, as well as the meshing power loss between the planet gears and the fixed internal gear ring, are calculated separately. For wind resistance loss, the planet gear part is approximately calculated using its rotational speed, and the wind resistance loss generated by the rotation of the planet carrier is additionally considered.

[0013] The power loss calculation of bevel gears is to treat them as equivalent to a cylindrical gear with the same tooth profile at the midpoint. During the conversion, the linear velocity at the midpoint of the bevel gear must be kept constant, and the back cone distance at the midpoint is used as the pitch circle diameter of the equivalent gear. Based on this, key parameters such as the equivalent number of teeth and the equivalent transmission ratio are derived, and finally, the corresponding power loss calculation formula is established.

[0014] In step 2, the power loss of the spur gear is calculated according to the Anderson and Loewenthal formula;

[0015] Its average sliding loss P S for:

[0016]

[0017] In the formula, f is the friction coefficient; The mean normal load is N; The average sliding speed is expressed in m / s. The average rolling speed is m / s; b is the tooth width, m (for gear pairs, the smaller tooth width is taken); μ0 is the dynamic viscosity of the lubricating oil, MPa·s; T1 is the applied torque, N·m; P is the transmission power, kW; n1 is the rotational speed, r / min; z is the number of teeth; g is the length of the meshing line, m; r a r is the radius of the tooth tip circle, m; b α is the base circle radius, m; r is the pitch circle radius, m; α is the pressure angle, °; footnote 1 represents the driving gear; footnote 2 represents the driven gear;

[0018] The rolling friction power loss of gears occurs when lubricating oil is squeezed between the teeth and pressurized. The average rolling loss P of spur gears R for:

[0019]

[0020] In the formula, ρ represents the EHD oil film thickness of the spur gears, in meters (m); ε represents the contact ratio of the spur gears; ρ represents the contact ratio of the spur gears. r is the equivalent radius of curvature of the spur gear, in meters; m is the gear module, in millimeters.

[0021] Spur gear wind resistance loss P W for:

[0022]

[0023] .

[0024] In step 3, if the transmission method is bevel gear transmission or cylindrical gear transmission, the total number of gears in that stage of transmission and the number of driving gears in the first stage need to be obtained to calculate the number of driving gears and driven gears in each stage. If the transmission method is planetary gear system transmission, the number of planetary gears in that stage needs to be obtained.

[0025] The calculation method for the number of driving and driven gears in each stage in step 3 is as follows:

[0026]

[0027] In the formula, N i2 N represents the number of driven gears in the i-th stage; isum N represents the total number of gears in the i-th stage; i1 Number of the i-th stage driving gears; N (i-1)2 This represents the number of driven gears in the (i-1)th stage.

[0028] In step 4, if the transmission method is bevel gear transmission or cylindrical gear transmission, the power loss calculation model for each stage is as follows:

[0029]

[0030] In the formula, N is the number of gear meshing pairs in this stage, which is the larger of the number of driving gears and the number of driven gears; N1 is the number of driving gears in this stage; N2 is the number of driven gears in this stage; P S The power loss due to sliding loss of this stage of gears is expressed in kW; P R The rolling loss power of this stage of gear is expressed in kW; P w1 The power loss due to oil resistance (wind resistance) of the driving gear in this stage is expressed in kW; P. w2 The power loss due to oil resistance (wind resistance) of the driven gear in this stage is expressed in kW.

[0031] If the transmission method in step 4 is a planetary gear train, the power loss calculation model for each stage is as follows:

[0032]

[0033] In the formula, c is the number of planetary gears in that stage.

[0034] Collect a database of helicopter transmission system configurations and summarize the transmission methods of bevel gear transmission and cylindrical gear transmission in helicopter transmission chains based on power flow paths; the transmission methods of bevel gear transmission and cylindrical gear transmission include ordinary, split torque, parallel, and coaxial multi-gear.

[0035] In step 5, the efficiency η of the transmission system is:

[0036]

[0037] In the formula, P0 is the input power, kW, P lossΣ The sum of power losses at each stage, expressed in kW.

[0038] Compared with the prior art, the advantages of the present invention are as follows:

[0039] By calculating the efficiency parameters such as gear type, transmission method, and gear parameters of each stage of the helicopter drivetrain, estimation results can be quickly generated, shortening the design cycle and making the drivetrain efficiency calculation process more systematic. This method can also be used in the subsequent helicopter drivetrain efficiency optimization process, greatly improving design efficiency. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating a method for estimating the transmission efficiency of helicopters applicable to various configurations in this case.

[0041] Figure 2 This is a structural diagram of an embodiment of the present case. Detailed Implementation

[0042] To clearly illustrate the technical features of the present invention, the present invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0043] like Figure 1 This is a flowchart illustrating a method for estimating the transmission chain efficiency of helicopters applicable to various configurations, as described in an embodiment of the present invention. Figure 1 As shown, the method includes, but is not limited to, the following steps:

[0044] Step 1: Collect helicopter transmission system configuration database and categorize the gear transmission methods in the helicopter transmission chain according to gear type; the gear transmission methods include bevel gear transmission, cylindrical gear transmission and planetary gear train transmission;

[0045] Step 2: Establish power loss calculation models for gear sets under different transmission methods according to the gear transmission method;

[0046] The power loss of spur gears in existing technologies is calculated using the Anderson and Loewenthal formula. This mainly includes gear rolling power loss, gear sliding power loss, and gear oil resistance (wind resistance) power loss.

[0047] The power loss calculation for planetary gear trains, based on the calculation of spur gears, is transformed into a virtual fixed-axis gear transmission system by applying a rotational speed equal to and opposite to the planet carrier's rotational speed to the entire planetary gear train. In this equivalent system, the meshing power loss between the sun gear and planet gears, and the meshing power loss between the planet gears and the fixed internal gear ring, are calculated separately. For wind resistance loss, the planet gear section is approximated by its rotational speed, with additional consideration given to the wind resistance loss caused by the planet carrier's rotation.

[0048] The power loss calculation for bevel gears involves treating them as equivalent to a cylindrical gear with the same tooth profile at its midpoint. During the conversion, the linear velocity at the midpoint of the bevel gear must remain constant, and the back cone distance at the midpoint is used as the pitch circle diameter of the equivalent gear. Based on this, key parameters such as the equivalent number of teeth and the equivalent transmission ratio are derived, ultimately establishing the corresponding power loss calculation formula.

[0049] The gear transmission methods include bevel gear transmission, cylindrical gear transmission, and planetary gear train transmission; the actual gear parameters include the gear module, number of teeth, tooth width coefficient, and helix angle.

[0050] Step 3: Obtain the number of driving gears and driven gears in each stage of transmission;

[0051] If the transmission method is bevel gear transmission or cylindrical gear transmission, the total number of gears in that stage of transmission and the number of driving gears in the first stage are needed to calculate the number of driving gears and driven gears in each stage. If the transmission method is planetary gear system transmission, the number of planetary gears in that stage is needed.

[0052] Step 4: Establish a power loss calculation model for the gear set;

[0053] If the transmission method is bevel gear transmission or cylindrical gear transmission, the power loss calculation model for each stage is as follows:

[0054]

[0055] In the formula, N is the number of gear meshing pairs in this stage, which is the larger of the number of driving gears and the number of driven gears; N1 is the number of driving gears in this stage; N2 is the number of driven gears in this stage; P S The power loss due to sliding loss of this stage of gears is expressed in kW; P R The rolling loss power of this stage of gear is expressed in kW; P w1 The power loss due to oil resistance (wind resistance) of the driving gear in this stage is expressed in kW; P.w2 The power loss due to oil resistance (wind resistance) of the driven gear in this stage is expressed in kW.

[0056] If the transmission method is a planetary gear system:

[0057]

[0058] In the formula, c is the number of planetary gears in that stage.

[0059] Collect a database of helicopter transmission system configurations and summarize the transmission methods of bevel gear transmission and cylindrical gear transmission in helicopter transmission chains according to the power flow path; the transmission methods of bevel gear transmission and cylindrical gear transmission include ordinary, split torque, parallel, and coaxial multi-gear.

[0060] Step 5: Based on the transmission mode of the gears in each gear group of the helicopter transmission chain to be estimated, select the power loss calculation model used for each gear group of the transmission chain. Combine the power loss of a single gear group in Step 2 to calculate the power loss of each gear group. After further superposition, obtain the power loss of the helicopter transmission chain, and then obtain the transmission system efficiency.

[0061] The efficiency η of the transmission system is:

[0062]

[0063] In the formula, P0 is the input power, kW, P lossΣ The sum of power losses at each stage, expressed in kW.

[0064] In step 2, the power loss of the spur gear is calculated according to the Anderson and Loewenthal formula;

[0065] Its average sliding loss P S for:

[0066]

[0067] In the formula, f is the friction coefficient; The mean normal load is N; The average sliding speed is expressed in m / s. The average rolling speed is m / s; b is the tooth width, m (for gear pairs, the smaller tooth width is taken); μ0 is the dynamic viscosity of the lubricating oil, MPa·s; T1 is the applied torque, N·m; P is the transmission power, kW; n1 is the rotational speed, r / min; z is the number of teeth; g is the length of the meshing line, m; r a r is the radius of the tooth tip circle, m; b α is the base circle radius, m; r is the pitch circle radius, m; α is the pressure angle, °; footnote 1 represents the driving gear; footnote 2 represents the driven gear;

[0068] The rolling friction power loss of gears occurs when lubricating oil is squeezed between the teeth and pressurized. The average rolling loss P of spur gears R for:

[0069]

[0070] In the formula, ρ represents the EHD oil film thickness of the spur gears, in meters (m); ε represents the contact ratio of the spur gears; ρ represents the contact ratio of the spur gears. r is the equivalent radius of curvature of the spur gear, in meters; m is the gear module, in millimeters.

[0071] Spur gear wind resistance loss P W for:

[0072]

[0073] .

[0074] The calculation method for the number of driving and driven gears in each stage in step 3 is as follows:

[0075]

[0076] In the formula, N i2 N represents the number of driven gears in the i-th stage; isum N represents the total number of gears in the i-th stage; i1 Number of the i-th stage driving gears; N (i-1)2 This represents the number of driven gears in the (i-1)th stage.

[0077] Example:

[0078] like Figure 2 This is a schematic diagram of the main reduction gear transmission of a helicopter, which uses a first-stage bevel gear set, a second-stage helical gear set, and a third-stage herringbone gear set. The first-stage bevel gear is a coaxial multi-gear ordinary transmission, the second-stage helical gear is a torque-split transmission, and the third-stage herringbone gear set is a parallel transmission.

[0079] Obtain the operating parameters of the helicopter: input power is 16000kW, rotor shaft power is 14710kW, and input speed is 8300r / min. Obtain the gear parameters of each stage of the helicopter's transmission chain: the first-stage bevel gear has a module of 6, a driving gear with 28 teeth, a face width coefficient of 0.32, a transmission ratio of 3.21, a helix angle of 40°, and a pressure angle of 25°; the second-stage helical gear has a module of 4.5, a driving gear with 32 teeth, a face width coefficient of 0.31, a transmission ratio of 3.47, a helix angle of 35°, and a pressure angle of 25°; the third-stage bevel gear has a module of 6.2, a driving gear with 23 teeth, a face width coefficient of 0.75, a transmission ratio of 5.6, a helix angle of 30°, and a pressure angle of 25°.

[0080] When calculating the efficiency of a single pair of gears in a single-stage bevel gear set, the following method is used:

[0081]

[0082] In the formula, r ma Let r be the radius of the apex circle at the midpoint, m; mb Let r be the radius of the base circle at the midpoint, m; m n is the equivalent pitch circle radius, m; v Z represents the equivalent speed of the bevel gear, in r / min; v δ represents the equivalent number of teeth; δ is the pitch cone angle, in °. Note 1 represents the driving gear; Note 2 represents the driven gear.

[0083] Average rolling loss P of bevel gears R for

[0084]

[0085] In the formula, ε α For end face overlap; m ms The midpoint end face module is in mm.

[0086] Bevel gear wind resistance loss P W for

[0087]

[0088]

[0089] When calculating the efficiency of a single-stage bevel gear set, the following method is used:

[0090]

[0091] In the formula, P S1 The power loss due to sliding of the first-stage bevel gear is expressed in kW; P R1 The rolling loss power of the first-stage bevel gear is expressed in kW; P w11 The power loss due to oil resistance (wind resistance) of the primary bevel gear drive gear is expressed in kW; P. w12 The power loss due to oil resistance (wind resistance) of the driven gear of the first-stage bevel gear is expressed in kW.

[0092] When calculating the efficiency of a single pair of gears for a two-stage helical gear set and a three-stage herringbone gear set, the following method is used:

[0093] The average sliding loss P of helical gears S for

[0094]

[0095] In the formula, g s α is the length of the meshing line, in meters; sβ is the end-face pressure angle, °; b The base circle helix angle is °.

[0096] Average rolling loss P of helical gears R for:

[0097]

[0098] In the formula, ε α This refers to the end face overlap.

[0099] Helical gear wind resistance loss P W for

[0100]

[0101]

[0102] When calculating the second-stage helical gear set, the following method is used:

[0103] ;

[0104] In the formula, P S2 The power loss due to sliding loss of the two-stage cylindrical gear is expressed in kW; P R2 The rolling loss power of the two-stage cylindrical gear is kW; P w21 The power loss due to oil resistance (wind resistance) of the secondary cylindrical gear drive gear is expressed in kW; P. w22 The power loss due to oil resistance (wind resistance) of the driven gear in the second-stage cylindrical gear is expressed in kW.

[0105] When calculating a three-stage herringbone gear set, the following method is used:

[0106] ;

[0107] In the formula, P S3 The power loss due to sliding of the third-stage cylindrical gear is expressed in kW; P R3 The rolling loss power of the third-stage cylindrical gear is kW; P w31 The power loss due to oil resistance (wind resistance) of the third-stage cylindrical gear drive gear is expressed in kW; P. w32 The power loss due to oil resistance (wind resistance) of the driven gear of the third-stage cylindrical gear is expressed in kW.

[0108] The rolling loss of the gears in this configuration helicopter is calculated to be 20.56kW, the sliding loss is 162.26kW, the wind resistance loss is 11.63kW, and the efficiency is approximately 98.78%.

[0109] In some embodiments, gear transmission methods can be classified by power flow, such as ordinary, split torque, parallel, and coaxial multi-gear.

[0110] In some embodiments, the gear transmission methods such as ordinary, split torque, parallel turning, and coaxial multi-drive gears, etc., ordinary means that each drive gear in this stage of transmission corresponds to one driven gear and there is only one drive gear on a shaft. Split torque means that each drive gear in this stage of transmission corresponds to two driven gears. Parallel turning means that multiple drive gears in this stage of transmission correspond to one driven gear. Coaxial multi-drive gears means that there are only two drive gears on the shaft in this stage of transmission.

[0111] There are many specific ways to implement this invention. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1. A method for estimating the efficiency of a helicopter transmission chain applicable to various configurations, characterized in that, Follow these steps: Step 1: Collect helicopter transmission system configuration database and categorize the gear transmission methods in the helicopter transmission chain according to gear type; the gear transmission methods include bevel gear transmission, cylindrical gear transmission and planetary gear train transmission; Step 2: Establish power loss calculation models for gear sets under different transmission methods according to the gear transmission method; Step 3: Obtain the number of driving gears and driven gears in each stage of transmission; Step 4: Establish a power loss calculation model for the gear set; Step 5: Based on the transmission mode of the gears in each gear group of the helicopter transmission chain to be estimated, select the power loss calculation model used for each gear group of the transmission chain. Combine the power loss of a single gear group in Step 2 to calculate the power loss of each gear group. After further superposition, obtain the power loss of the helicopter transmission chain, and then obtain the transmission system efficiency.

2. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 1, characterized in that, The gear transmission methods mentioned in step 2 include spur gear transmission, helical gear and herringbone gear transmission, planetary gear train transmission and bevel gear transmission; The power loss of spur gears is calculated according to the Anderson and Loewenthal formula, including gear rolling power loss, gear sliding power loss and gear oil resistance (wind resistance) power loss; The power loss calculation for helical gears and herringbone gears is based on the power loss calculation for spur gears, but the helix angle of the helical gears is taken into account during the calculation. The power loss calculation of planetary gear trains is based on the power loss calculation of spur gears. By applying a rotational speed equal to and opposite to the planet carrier speed to the entire planetary gear train, it is transformed into a virtual fixed-axis gear transmission system. In this equivalent system, the meshing power loss between the sun gear and planet gears, as well as the meshing power loss between the planet gears and the fixed internal gear ring, are calculated separately. For wind resistance loss, the planet gear part is approximately calculated using its rotational speed, and the wind resistance loss generated by the rotation of the planet carrier is additionally considered. The power loss calculation of bevel gears is to treat them as equivalent to a cylindrical gear with the same tooth profile at the midpoint. During the conversion, the linear velocity at the midpoint of the bevel gear must be kept constant, and the back cone distance at the midpoint is used as the pitch circle diameter of the equivalent gear. Based on this, key parameters such as the equivalent number of teeth and the equivalent transmission ratio are derived, and finally, the corresponding power loss calculation formula is established.

3. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 2, characterized in that, In step 2, the power loss of the spur gear is calculated according to the Anderson and Loewenthal formula; Its average sliding loss P S for: ； In the formula, f is the friction coefficient; The mean normal load is N; The average sliding speed is expressed in m / s. 1 is the average rolling speed, m / s; b is the tooth width, m (for gear pairs, take the smaller tooth width); μ0 is the dynamic viscosity of the lubricating oil, MPa·s; T1 is the applied torque, N·m; P is the transmission power, kW; n1 is the rotational speed, r / min; z is the number of teeth; g is the length of the meshing line, m; r a r is the radius of the tooth tip circle, m; b α is the base circle radius, m; r is the pitch circle radius, m; α is the pressure angle, °; footnote 1 represents the driving gear; footnote 2 represents the driven gear; The rolling friction power loss of gears occurs when lubricating oil is squeezed between the teeth and pressurized. The average rolling loss P of spur gears R for: ； In the formula, The EHD oil film thickness for spur gears is in meters (m). ε is the contact ratio of spur gears; ρ r is the equivalent radius of curvature of the spur gear, in m; m is the gear module, in mm; Spur gear wind resistance loss P W for: ； 。 4. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 1, characterized in that, In step 3, if the transmission method is bevel gear transmission or cylindrical gear transmission, the total number of gears in that stage of transmission and the number of driving gears in the first stage need to be obtained to calculate the number of driving gears and driven gears in each stage. If the transmission method is planetary gear system transmission, the number of planetary gears in that stage needs to be obtained.

5. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 4, characterized in that, The calculation method for the number of driving and driven gears in each stage in step 3 is as follows: ； In the formula, N i2 N represents the number of driven gears in the i-th stage; isum N represents the total number of gears in the i-th stage; i1 Number of the i-th stage driving gears; N (i-1)2 This represents the number of driven gears in the (i-1)th stage.

6. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 1, characterized in that, In step 4, if the transmission method is bevel gear transmission or cylindrical gear transmission, the power loss calculation model for each stage is as follows: ； In the formula, N is the number of gear meshing pairs in this stage, which is the larger of the number of driving gears and the number of driven gears; N1 is the number of driving gears in this stage; N2 is the number of driven gears in this stage; P S The power loss due to sliding loss of this stage of gears is expressed in kW; P R The rolling loss power of this stage of gear is expressed in kW; P w1 The power loss due to oil resistance (wind resistance) of the driving gear in this stage is expressed in kW; P. w2 The power loss due to oil resistance (wind resistance) of the driven gear in this stage is expressed in kW.

7. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 1, characterized in that, If the transmission method in step 4 is a planetary gear train, the power loss calculation model for each stage is as follows: ； In the formula, c is the number of planetary gears in that stage; Collect a database of helicopter transmission system configurations and summarize the transmission methods of bevel gear transmission and cylindrical gear transmission in helicopter transmission chains based on power flow paths; the transmission methods of bevel gear transmission and cylindrical gear transmission include ordinary, split torque, parallel, and coaxial multi-gear.

8. The method for estimating the transmission chain efficiency of helicopters applicable to various configurations according to claim 1, characterized in that, In step 5, the efficiency η of the transmission system is: ； In the formula, P0 is the input power, kW, P lossΣ The sum of power losses at each stage, expressed in kW.

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