Two-stage RV reducer based on dual-source power split and method for suppressing thermal deformation thereof

Abstract

This invention relates to the field of speed reducer technology, specifically disclosing a two-stage RV speed reducer based on dual-source power splitting and its thermal deformation suppression method. The method includes: using two symmetrically distributed input pinions to drive a first-stage large gear, uniformly splitting the input load during the first-stage reduction process, and constructing a centrally symmetrical temperature field distribution within the speed reducer to reduce the temperature rise curve; quantitatively calculating the thermo-elastic coupling deformation of the second-stage cycloidal pinwheel based on the reduced temperature rise curve, enabling adaptive clearance compensation of the tooth profile for the reserved initial tooth clearance under dynamic temperature field; constructing an internal hot airflow circulation path based on axial heat convection holes pre-drilled on the first-stage large gear; and physically thermally isolating the heat generated in the first-stage meshing zone from the second-stage cycloidal pinwheel based on the internal hot airflow circulation path, and dissipating the heat. This invention can suppress heat generation at the source, ensuring the meshing stiffness stability and dynamic accuracy of the speed reducer under wide temperature range conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of speed reducer, more particularly to a thermal deformation inhibition method of two-stage RV reducer based on double-source power split. BACKGROUND

[0002] As the core transmission component of precise robot joints, RV reducer has significant advantages in large transmission ratio, high rigidity and high load capacity. However, the heat of the first-stage involute planetary transmission and the second-stage cycloid pin wheel transmission of the traditional single-input structure RV reducer is highly concentrated in the single-sided meshing area. According to the friction heat flux density theory, single-path transmission leads to excessive contact stress, causing serious local heat generation, resulting in uneven temperature field of the cycloid pair. This heat accumulation will cause significant radial thermal expansion of the cycloid pin wheel, not only deteriorating the meshing accuracy, but also causing severe fluctuations in the thermal stiffness of the system, resulting in serious dynamic transmission error.

[0003] To solve the above-mentioned temperature rise problem, the existing technology usually adopts increasing external forced cooling system or implementing pre-geometric compensation. Although forced cooling can reduce the surface temperature to a certain extent, it increases the complexity and axial size of the system, and cannot fundamentally eliminate the asymmetric thermal distortion caused by single-sided input; and the traditional equidistant or shifted tooth profile modification is designed based on normal temperature conditions, which belongs to static compensation. In actual operation, with the nonlinear change of heat generation caused by load fluctuation, this static modification is difficult to adapt to the dynamic evolution of thermal deformation, resulting in inconsistent meshing state of the reducer under different loads, and even tooth surface pitting and burning caused by thermal expansion under high temperature.

[0004] Therefore, how to inhibit heat generation from the source and ensure the stability of the meshing stiffness and dynamic accuracy of the reducer under wide temperature range conditions is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] In view of the above problems, the present application provides a thermal deformation inhibition method of two-stage RV reducer based on double-source power split, so as to overcome the above problems or at least partially solve the above problems.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] In the first aspect, the present application provides a thermal deformation inhibition method of two-stage RV reducer based on double-source power split, comprising the following steps:

[0008] The two symmetrically distributed input pinions drive the first-stage gear, evenly split the input load in the first-stage reduction process, and build a central symmetric temperature field distribution inside the reducer, so as to reduce the temperature rise curve;

[0009] Quantify the thermal-elastic coupling deformation of the secondary cycloid pin wheel based on the reduced temperature rise curve, and make the tooth profile self-adaptive gap compensation to the reserved initial intertooth gap under the dynamic temperature field based on the thermal-elastic coupling deformation;

[0010] Based on the axial heat convection hole previously opened on the primary gear, an internal heat flow circulation path is constructed; based on the internal heat flow circulation path, the heat generated in the primary meshing area is physically isolated from the secondary cycloid pin wheel, and the heat is discharged.

[0011] Further, the process of uniformly distributing the input load during the primary reduction process includes:

[0012] Based on the two-way symmetric distribution of the input pinion, the input load borne by each meshing point is reduced from F to F / 2;

[0013] Based on the reduced load F / 2, the contact stress of the meshing point after distribution is calculated , the contact stress of the meshing point after distribution , is the contact stress of the meshing point before distribution;

[0014] Based on the contact stress of the meshing point after distribution , the unit area friction heat flux density is calculated , and the calculation formula is:

[0015]

[0016] Among them, is the relative sliding speed, is the friction coefficient, is the conversion coefficient.

[0017] Further, the mathematical expression of the temperature field distribution is:

[0018]

[0019] Among them, represents the heat source generated by the two symmetrically distributed input pinions, represents the thermal conductivity of the reducer structure material, represents the Laplace operator, represents the temperature field, represents the mass density of the reducer structure material, represents the specific heat capacity of the reducer structure material, represents the time variable, represents the transient temperature rise rate of temperature change with time.

[0020] Furthermore, during the manufacturing stage of the reducer, the standard tooth profile is pre-machined using a preset variable equidistant profile modification curve, leaving an initial clearance between the teeth. The expression for the variable equidistant profile modification curve is:

[0021]

[0022] in, This indicates the preset radial trimming amount, which is the thickness of metal that is pre-ground away during the reducer manufacturing stage; This represents the compensation correction coefficient, which is determined based on the linear expansion coefficient and rated temperature rise slope of the cycloidal wheel material, and is used to scale the compensation intensity. This represents the peak value of the maximum thermal deformation displacement calculated under rated operating conditions; This indicates the phase angle of the eccentric shaft rotation.

[0023] Furthermore, the compensation correction coefficient The determination process includes:

[0024] The thermo-elastic coupling displacement field of the cycloidal wheel during the entire phase period was obtained by using the finite element analysis method, and a least-squares objective function was established between the preset radial deformation and the actual thermal deformation.

[0025] With minimizing the standard deviation of the full-phase meshing clearance as the optimization objective, the compensation correction coefficient is iteratively adjusted until the overlap between the actual tooth profile trajectory and the ideal tooth profile under hot conditions reaches the engineering design threshold, thus obtaining the optimal solution adapted to specific working conditions. value.

[0026] Furthermore, the formula for calculating the thermo-elastic coupling deformation is as follows:

[0027]

[0028] in, This represents the amount of thermo-elastic coupling deformation. It represents the rotation angle of the eccentric shaft, reflecting the phase of the meshing point in time or space; These represent the geometric characteristic parameters of the cycloidal pinwheel transmission mechanism. This indicates the maximum physical elastic contact deformation of the cycloidal pin teeth under rated load; This represents the radial thermal expansion displacement increment of the cycloidal wheel caused by a non-uniform temperature field under a specific temperature rise curve.

[0029] Furthermore, the geometric characteristic parameters of the cycloidal pinwheel transmission mechanism Defined as: ,in, This is the short amplitude coefficient.

[0030] Furthermore, the formula for calculating the axial convection heat transfer coefficient of the internal hot air circulation path is as follows:

[0031]

[0032] in, It represents the axial convection heat transfer coefficient, used to reflect the heat dissipation rate; This represents the thermal conductivity of air. This represents the temperature distribution index, used to describe the radial distribution of temperature. The Prandtl number, representing air, is used to characterize the effect of fluid physical properties on heat transfer. This indicates the rotational angular velocity of the large first-stage gear; This indicates the kinematic viscosity of air.

[0033] Secondly, the present invention provides a two-stage RV reducer based on dual-source power splitting, which suppresses thermal deformation during operation in accordance with the method described above.

[0034] Furthermore, the reducer includes a primary flow divider reduction mechanism and a secondary eccentric transmission mechanism;

[0035] The primary flow divider deceleration mechanism includes a primary large gear and two input small gears; the two input small gears are symmetrically distributed around the primary large gear and drive the primary large gear to rotate; axial heat convection holes are provided on the web of the primary large gear.

[0036] The secondary eccentric transmission mechanism includes three evenly distributed eccentric shafts driven by a primary large gear. Each eccentric shaft is fitted with a cycloidal wheel, and an initial clearance is reserved between the tooth profiles of the cycloidal wheels.

[0037] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0038] This invention utilizes a dual-source split-flow transmission structure where two small gears drive a large gear, achieving power splitting in the first-stage deceleration phase. This theoretically reduces the contact stress and heat flux density at a single meshing point by 50%, suppressing heat generation at its source. Furthermore, a centrally symmetrical temperature field is constructed using a dual-input 180° symmetrical layout, transforming the thermal distortion of the cycloidal pair from asymmetric eccentric expansion to controlled centrally symmetrical expansion.

[0039] Based on this, the present invention realizes adaptive tooth profile modification under thermal deformation. Due to the significant reduction in temperature rise peak caused by dual-source drive, the thermal-elastic coupling deformation fluctuation range of the cycloidal wheel in the full load range is significantly reduced, so that the initial modification curve can better adapt to the dynamically evolving thermal effect, ensuring the meshing stiffness stability and dynamic accuracy of the reducer under wide temperature range conditions.

[0040] Finally, this invention transforms the original enclosed air layer into a forced convection duct by creating convection holes on the large gear. At the same rotational speed, the air disturbance caused by the porous structure increases dramatically, thinning the laminar boundary layer and significantly improving the local convective heat transfer coefficient. Consequently, the high temperature generated at the primary meshing point is absorbed by the large gear, and the forced airflow within the convection holes carries away the heat through convection heat transfer before it is conducted to the secondary eccentric shaft. This active heat removal mechanism ensures that the ambient temperature fluctuation of the secondary cycloidal pair is always limited within the adaptive range, preventing heat from spreading upstream / downstream and achieving a physical decoupling of precision and thermal load. This physically isolates and forcibly removes the heat generated in the primary meshing area from the secondary precision transmission part, ensuring that the secondary precision pair always operates within a constant temperature envelope, achieving a deep decoupling of transmission precision and thermal load. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0042] Figure 1 The flowchart shows the thermal deformation suppression method for a two-stage RV reducer based on dual-source power splitting provided in this embodiment of the invention.

[0043] Figure 2 This is a schematic diagram of the structure of a two-stage RV reducer based on dual-source power splitting provided in an embodiment of the present invention.

[0044] In the diagram, 1 is the primary gear, 2 is the input pinion, 3 is the eccentric shaft, 4 is the cycloidal wheel, and 5 is the axial heat convection hole. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] like Figure 1 As shown in the figure, this invention discloses a method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting, comprising the following steps:

[0047] S1. Two symmetrically distributed input pinions drive a first-stage large gear, which uniformly distributes the input load during the first-stage deceleration process and constructs a centrally symmetrical temperature field distribution inside the reducer, thereby reducing the temperature rise curve.

[0048] S2. Quantitatively calculate the thermo-elastic coupling deformation of the secondary cycloidal pinwheel based on the reduced temperature rise curve, and make the tooth profile adaptively compensate for the reserved initial tooth gap under the dynamic temperature field based on the thermo-elastic coupling deformation.

[0049] S3. Based on the axial heat convection holes pre-drilled on the first-stage large gear, an internal hot airflow circulation path is constructed; based on the internal hot airflow circulation path, the heat generated in the first-stage meshing area is physically thermally isolated from the second-stage cycloidal pinwheel, and the heat is discharged.

[0050] The following provides further explanation of each of the above steps.

[0051] S1. Two symmetrically distributed input pinions drive the first-stage large gear, which uniformly distributes the input load during the first-stage deceleration process and constructs a centrally symmetrical temperature field distribution inside the reducer, thereby reducing the temperature rise curve.

[0052] The process of uniformly distributing the input load during the first-stage deceleration includes:

[0053] Based on the two symmetrically distributed input pinions, the input load borne by each meshing point is reduced from F to F / 2;

[0054] Calculate the contact stress at the meshing point after the flow split based on the reduced load F / 2. According to Hertz's contact stress formula, the original gear meshing point contact stress before flow splitting... :

[0055]

[0056] in, For normal load, For tooth width, The radius of curvature is the composite radius.

[0057] When a symmetrical layout of two input pinions is adopted, the normal load borne by each meshing point is... Reduced to .because and Proportional to the contact stress at the meshing point after flow splitting ;

[0058] Based on the contact stress at the meshing point after flow splitting Calculate the frictional heat flux density per unit area The calculation formula is:

[0059]

[0060] in, The relative sliding speed, The coefficient of friction, The conversion factor is used to reduce the normal load at the single-path engagement point through dual-source shunt. Reduce by 50%, according to Hertz's contact stress formula Single-point contact stress A significant decrease, thus in relative sliding speed coefficient of friction Under the premise of keeping things unchanged, achieve the frictional heat flux density per unit area. The quantification and dilution process suppresses the rate of temperature rise from the heat source, ultimately achieving a single-point heat flux density. It decreased by approximately 29.3%.

[0061] In this step, the first-stage deceleration process is defined as the "power shunt and thermal management buffer stage".

[0062] Its physical structure consists of two spatially symmetrical power input ends (small gears) and a common load end (central large gear).

[0063] Functionally positioned as follows: Unlike traditional RV reducers that are merely considered speed ratio conversion stages, this invention treats it as a "physical dilution zone for the heat source." By splitting the total input torque in half during the first-stage transmission, the energy is in a controlled splitting state as soon as it enters the reducer, providing a low-base temperature field environment for the thermal stability of the subsequent second-stage precision reduction section.

[0064] The process of establishing a centrosymmetric temperature field distribution inside the reducer includes:

[0065] This invention utilizes the geometric feature of two input sources arranged in a 180° mirror configuration to construct a centrally symmetric temperature field distribution within the reducer. Based on the transient heat conduction differential equation, we obtain:

[0066]

[0067] in, This represents the heat source generated by two symmetrically distributed input pinions. This indicates the thermal conductivity of the material used in the reducer structure. This represents the Laplace operator, used to describe the second-order partial derivatives of the temperature field in the spatial dimension. Represents the temperature field. This indicates the mass density of the material used in the reducer's structure. This indicates the specific heat capacity of the material used in the reducer's structure. Represents a time variable. This represents the transient rate of temperature rise over time.

[0068] This invention utilizes dual heat sources The symmetrical arrangement of the gears and the second-stage precision reduction gears improves the temperature field of the large gear and the second-stage precision reduction gear. In the circumferential angle The structure exhibits periodic symmetry. In contrast to the non-uniform temperature field generated by a single heat source, the radial thermal expansion stress generated by this invention cancels each other out at the center of the structure, physically eliminating the axial eccentricity distortion and central axis offset caused by unilateral heating.

[0069] S2. Based on the reduced temperature rise curve, the thermo-elastic coupling deformation of the secondary cycloidal pinwheel is quantitatively calculated. Based on the thermo-elastic coupling deformation, the tooth profile is adaptively compensated for the reserved initial tooth clearance under the dynamic temperature field. Specifically, this includes:

[0070] Based on the reduced temperature rise curve in step S1, the thermo-elastic coupling deformation of the secondary cycloidal pinwheel is quantitatively calculated. The first-stage reduction process, through dual-source flow splitting, directly determines the dynamic boundary and thermodynamic environment of the second-stage cycloidal pinwheel. The dynamic correlation is as follows: the large gear in the first stage synchronously transmits the split torque to the second-stage eccentric shaft, thus increasing the normal force borne by a single cycloidal pinwheel. A theoretical decrease of 50% directly alters the elastic deformation term in the formula. The thermodynamic correlation is as follows: the equilibrium temperature field generated by the first-order symmetrical layout serves as the initial boundary condition for the second-order mechanism. By reducing environmental thermal stress, this decreases the thermal expansion increment in the second-order calculation formula. .

[0071] The formula for calculating thermo-elastic coupling deformation is:

[0072]

[0073] This formula describes the combined deformation of the cycloidal pin teeth under thermoelastic coupling conditions, where, This represents the amount of thermo-elastic coupling deformation. It indicates the rotation angle of the eccentric shaft or the rotation angle of the arm, reflecting the phase of the meshing point in time or space; The geometric characteristic parameters of the cycloidal pinwheel transmission mechanism are defined as follows: ,in, This is the short amplitude coefficient. This represents the maximum physical elastic contact deformation of the cycloidal pin teeth under rated load, caused by Hertzian stress. This represents the radial thermal expansion displacement increment of the cycloidal wheel caused by a non-uniform temperature field under a specific temperature rise curve.

[0074] This step involves establishing a three-dimensional precise finite element model of the cycloidal wheel and discretizing the mesh, then calculating the frictional heat flux density after the first-stage flow split. The hot surface load is applied to the meshing contact area of ​​the tooth profile, and the convective heat transfer coefficient derived from physical formulas is defined on the X surface of the axial convection channel. First, the steady-state thermal equilibrium equation is solved to obtain the non-uniform temperature field distribution across the entire cycloidal wheel. Then, this temperature field is mapped in real time as a body load into the structural dynamics analysis step, combined with the mechanical normal force after the first-stage load reduction. Thermo-structural joint iterative solution is performed using eccentric support constraints. Coordinate transformation technology is used to filter out the rigid body displacement and elastic deformation under stress of the cycloidal wheel, thereby accurately separating the pure radial expansion displacement component induced by temperature rise. The maximum thermal deformation increment is ultimately determined by extracting the peak value of the distribution envelope of the displacement field during the full-phase meshing period. This provides data support for the physical fitting of the subsequent variable equidistant shaping curve.

[0075] In this step, the frictional heat flux density after the first-stage flow split is substituted into the thermal-structural coupled finite element analysis method. Calculate the radial displacement field of the cycloidal wheel under steady-state temperature field, and take the maximum value of its distribution envelope as... The total deformation fluctuation range under stress and temperature rise The dual-input structure reduces... It reduced elastic fluctuations and lowered the temperature through shunt temperature control. Peak value. According to the formula, the simultaneous contraction of both increments significantly narrows the total displacement range of the cycloidal wheel from the cold state to the hot state.

[0076] This invention reduces the peak thermal deformation. This significantly narrows the fluctuation range of the total deformation of the cycloidal gear across the entire load range. Simulations of the cycloidal gear's deformation under steady-state temperature conditions reveal that the thermal deformation is close to zero at the tooth root and reaches its maximum value at the tooth tip. And the amount of deformation varies with the rotation angle. The distribution curve and The functions have a high degree of similarity in appearance.

[0077] During the manufacturing stage of the reducer, the standard tooth profile is pre-machined using a preset variable equidistant profile curve, leaving an initial clearance between the teeth. The expression for the variable equidistant profile curve is:

[0078]

[0079] in, This indicates the preset radial trimming amount, which is the thickness of metal that is pre-ground away during the reducer manufacturing stage; This represents the compensation correction coefficient, which is determined based on the linear expansion coefficient and rated temperature rise slope of the cycloidal wheel material, and is used to scale the compensation intensity. This represents the peak value of the maximum thermal deformation displacement calculated under rated operating conditions; This represents the phase angle of the eccentric shaft rotation, used to achieve a precise correspondence between the phase of each point on the tooth profile and the phase of the temperature field.

[0080] and These factors respectively constitute the peak value of the thermally induced increment and the mechanoelastic reference of the total deformation of the cycloidal pair. They exhibit a linear superposition relationship in the thermo-elastic coupling deformation formula, jointly determining the comprehensive displacement characteristics and the target quantity of adaptive compensation of the system under temperature rise conditions. Based on the frictional heat flux density after power splitting in S1 The maximum value of the radial displacement distribution envelope was extracted through simulation using the thermo-structural coupled finite element analysis method. Based on the Hertzian contact stress model, the maximum physical elastic extrusion depth of the tooth surface is derived through physical formulas under rated load. By substituting these two key parameters from different physical fields into the coupled model, the preset variable equidistant shaping curve is achieved. Precise parameter calibration and dynamic fitting of physical dimensions.

[0081] Specifically, during the reducer manufacturing stage, a CNC gear grinding machine is used to modify the shape according to the variable equidistant profile curve. Subtractive machining is performed on the standard tooth profile. At this point, the cycloidal tooth profile is in a "undersized" state, with initial clearance between the teeth caused by the profile modification. During operation, frictional heat induces radial expansion of the cycloidal wheel. Due to thermal deformation With shaping volume Sharing the same independent variable - angle Both follow the cosine distribution logic, and the two achieve real-time superposition of peak to peak and trough to trough in physical space. The optimization process is an iterative calibration process based on thermo-structural coupling simulation and residual minimization: First, the thermo-elastic coupling displacement field of the cycloidal wheel during the full-phase period is obtained using the finite element analysis method. A least-squares objective function is established between the preset radial clearance and the actual thermal deformation. The optimization objective is to minimize the standard deviation of the full-phase meshing clearance. The compensation correction coefficient is iteratively corrected until the overlap between the actual tooth profile trajectory and the ideal tooth profile under hot conditions reaches the engineering design threshold, thereby accurately calibrating the optimal tooth profile suitable for specific working conditions. Value. When After optimization, the expansion displacement can fill the preset shaping space (i.e., the initial gap), making the actual tooth profile under hot conditions infinitely close to the ideal theoretical curve.

[0082] Ensure actual thermal deformation Just fills the preset shaping amount The core principle lies in the phase alignment and magnitude constraint of physical characteristics: the radial thermal expansion displacement of the cycloidal wheel is affected by the geometric constraints of the tooth profile, naturally exhibiting a periodic characteristic of large tooth tip and small tooth root, which is consistent with the preset... The cosine-modified curve is completely synchronized in physical space phase; combined with the first-stage dual-source diversion mechanism to effectively suppress the temperature rise rate, the expansion displacement of the metal material under steady-state temperature field exhibits extremely high linearity and geometric similarity, thereby driving the positive expansion generated by heating to accurately fill the negative gap reserved by subtraction processing, realizing dynamic gap self-compensation in the physical dimension by utilizing the thermodynamic properties of the material without external feedback.

[0083] During the specific operation phase, assuming that operating condition A is the startup phase, the overall temperature is low: the reducer temperature rise is low, and the thermal deformation is minimal. At this point, the meshing clearance is mainly determined by the preset profile adjustment amount, and the system is in a low-friction, large-clearance state, facilitating rapid start-up. Assuming operating condition B is heavy-load operation / temperature rise period: as the temperature rises, the cycloidal wheel's metal material expands outward. Due to the reserved profile adjustment space, the expansion displacement is absorbed by the profile adjustment clearance and will not directly squeeze the pin teeth. Adaptive mechanism: the higher the temperature rise, the greater the expansion, and the fuller the profile adjustment space is filled, thereby achieving adaptive clearance compensation of the tooth profile under dynamic thermal field and maintaining the stability of meshing stiffness.

[0084] S3. Based on the axial heat convection holes pre-drilled on the primary gear, an internal hot airflow circulation path is constructed; based on the internal hot airflow circulation path, the heat generated in the primary meshing area is physically thermally isolated from the secondary cycloidal pinwheel, and the heat is discharged, specifically including:

[0085] Axial convection holes are evenly distributed on the web of the large primary gear. The centrifugal force and pressure gradient generated by the dual-drive rotation create an internal hot airflow circulation path. When the large gear rotates at high speed with the dual drive sources, air inside the holes and on the gear surface is thrown radially out by centrifugal force. This radially thrown air creates a localized low-pressure zone at the gear center and the axial hole inlet, forming a pressure gradient with the outside of the reducer (or non-heat-generating areas). Coupling relationship: This pressure difference forces air to flow within the axial orifice, increasing the rotational angular velocity. This is converted into the characteristic flow velocity of the air inside the orifice. This velocity is directly substituted into... In the calculation formula The item serves as the power source for driving heat exchange.

[0086] The formula for calculating the axial convection heat transfer coefficient of the internal hot air circulation path is:

[0087]

[0088] in, This represents the axial convective heat transfer coefficient, with units of . This is used to reflect the heat dissipation rate; This represents the thermal conductivity of air. This represents the temperature distribution index, used to describe the radial distribution of temperature, and is usually taken as a fixed value of 2. The Prandtl number, representing air, is used to characterize the effect of fluid physical properties on heat transfer. It represents the rotational angular velocity of the large primary gear, which is proportional to the rotational speed at both input ends; This indicates the kinematic viscosity of air.

[0089] By creating convection holes in the large gear, the original "closed air layer" is transformed into a "forced convection air duct." At the same rotational speed... In this case, the air turbulence in the porous structure increases dramatically, causing the laminar boundary layer to thin and thus significantly increasing the local convective heat transfer coefficient. Thus, the high temperature generated at the primary engagement point is absorbed by the large gear, and the forced airflow within the convection orifice carries away the heat through convection heat transfer before it is conducted to the secondary eccentric shaft. This active heat dissipation mechanism ensures minimal ambient temperature fluctuations in the secondary cycloidal pair. The heat is always confined within the adaptive range (envelope), preventing it from spreading upstream / downstream and achieving a physical decoupling of accuracy and thermal load. This physically isolates and forces the heat generated in the primary engagement zone from the secondary precision transmission unit, ensuring that the secondary precision pair always operates within a constant temperature envelope, achieving a deep decoupling of transmission accuracy and thermal load.

[0090] Based on steps S1-S3 above, this invention, by constructing a frictional heat flux density dilution model based on Hertzian contact stress, can accurately capture and quantify the contact stress at the meshing point. Regarding the impact on system heat generation, a 180° mirror-arranged power split architecture was used to physically halve the single-path meshing load, ensuring that the system can effectively manage instantaneous heat flux density when high load impacts are detected. This invention achieves a significant reduction, suppressing the surge in heat sources at the source. Unlike traditional solutions that rely on external strong cooling for hysteresis compensation, this invention utilizes the thermal stress center offsetting characteristics generated by the symmetrical distribution of dual heat sources. This allows the gear meshing parameters to evolve smoothly during dynamic temperature rise, effectively eliminating shaft misalignment and transmission jerking caused by unilateral heating, and greatly enhancing the smoothness of the trajectory and positioning accuracy in precision transmission.

[0091] Meanwhile, this invention innovatively introduces a physically adaptive logic based on variable isometric shaping, which adjusts the thermoelastic coupling deformation amount... The secondary confirmation accurately identified and compensated for the tooth expansion interference caused by frictional temperature rise, significantly enhancing the system's anti-jamming capability and mechanical robustness under extreme continuous operating environments, and ensuring the stability of the return clearance output under severe load fluctuations. In engineering applications, this invention fully utilizes the inherent compact spatial layout of the RV reducer, by opening a high-convective-heat-transfer coefficient on the large gear. The axial heat channel eliminates the need for expensive hardware such as additional water-cooled pumps and high-precision thermal sensors, offering significant advantages such as simple structure and ease of rapid deployment in standardized industrial robot joints. Ultimately, through this deep decoupling strategy integrating "load-thermal field-precision," the precision reducer gains the ability to sense and absorb its own frictional temperature rise, significantly improving the trajectory tracking accuracy and service life of the industrial robot's precision control system. This provides a highly reliable, efficient, and commercially viable thermal steady-state compensation solution for the high-precision transmission field.

[0092] In other embodiments, the present invention also provides a two-stage RV reducer based on dual-source power splitting, which suppresses thermal deformation during operation in accordance with the method described above.

[0093] Specifically, such as Figure 2 As shown, the reducer includes a primary flow splitting reduction mechanism and a secondary eccentric transmission mechanism; the primary flow splitting reduction mechanism and the secondary eccentric transmission mechanism are longitudinally integrated;

[0094] The first-stage flow divider and deceleration mechanism includes a first-stage large gear 1 and two input small gears 2; the two input small gears 2 are symmetrically distributed around the first-stage large gear 1 and drive the first-stage large gear to rotate; the first-stage large gear 1 serves as the output end of the first-stage flow divider and deceleration mechanism and the input end of the second-stage eccentric transmission mechanism; and axial heat convection holes 5 are opened on the web of the large gear to construct an internal heat exchange duct.

[0095] The secondary eccentric transmission mechanism includes three evenly distributed eccentric shafts 3 driven by a primary large gear. Each eccentric shaft is fitted with a cycloidal wheel 4, and an initial clearance is reserved between the tooth profiles of the cycloidal wheels.

[0096] Below, we will use the RV-20E reducer, which is commonly used in industrial robot joints, as a benchmark for parametric design and verification.

[0097] 1) Structural parameter configuration:

[0098] Single-stage reduction mechanism: Utilizes dual-drive pinions symmetrically arranged on both sides of the central large gear, with a phase angle of... Total input torque transmission ratio .

[0099] Second-level precision RV section: number of cycloidal teeth Number of needle teeth eccentricity needle radius cycloidal wheel width .

[0100] 2) Quantitative dilution calculation of frictional heat flux density:

[0101] At rated load Under operating conditions, a comparison is made between the traditional single-drive structure and the present invention:

[0102] Traditional single drive: meshing point normal load Substituting into the Hertzian stress formula:

[0103]

[0104] Calculated initial contact stress .

[0105] This invention features dual-source flow splitting: single-path meshing load. Substitute into the formula to calculate:

[0106]

[0107] Results confirm that contact stress decreased by approximately 29.3%. Based on the heat flux density formula... At sliding speed At constant temperature, the heat flux density per unit area This resulted in a significant decrease, reducing the system's temperature rise slope by approximately 35% from the source.

[0108] 3) Construction and compensation effect of the centrally symmetric temperature field:

[0109] Based on the transient heat conduction differential equation, the boundary conditions are set as follows: ambient temperature. initial temperature of lubricating oil .

[0110] Traditional solution: A single heat source causes localized temperature rise in the cycloidal wheel. This results in non-uniform thermal distortion.

[0111] This invention features a symmetrically distributed dual heat source. Through finite element thermal-structural coupling analysis, the temperature field gradient on the surface of the cycloidal wheel exhibits periodic symmetry. The thermal deformation of the cycloidal wheel is then... From one side Reduce to .

[0112] Physical meaning: The 180° symmetrical layout causes a geometrical eccentricity due to thermal stress. This physically eliminates the thermally induced deviation of the secondary input axis.

[0113] 4) Adaptive optimization of tooth profile modification under hot deformation:

[0114] Based on the variable equidistant shaping formula, set the adjustment coefficient. :

[0115]

[0116] Because this invention will maximize thermal deformation from Suppressed This reduces the residual range between the preset shaping amount and the thermal deformation amount by 42%.

[0117] Conclusion: Within the operating temperature rise range, the backlash fluctuation of the reducer changes from its original value... Optimized to near theoretical level The adaptive equilibrium state.

[0118] 5) Data on the improvement in forced heat exchange efficiency:

[0119] Six diameter slots are evenly distributed on the primary gear. Axial convection holes. Substituting into the convection heat transfer coefficient formula, when the large gear rotates... At that time, the convective heat transfer coefficient was calculated. It improves upon the non-porous structure by 22.5%.

[0120] Thermal isolation effect: Experimental data shows that the heat transfer rate from the primary meshing zone to the secondary precision part decreased by 18%, ensuring that the secondary cycloidal pair is always within its designed optimal thermal deformation envelope.

[0121] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting, characterized in that, Includes the following steps: Two symmetrically distributed input pinions drive a single-stage large gear, which uniformly distributes the input load during the first-stage deceleration process and constructs a centrally symmetrical temperature field distribution inside the reducer, thereby reducing the temperature rise curve. The thermo-elastic coupling deformation of the secondary cycloidal pinwheel is quantitatively calculated based on the reduced temperature rise curve. Based on the thermo-elastic coupling deformation, the tooth profile is adaptively compensated for the reserved initial gap between teeth under the dynamic temperature field. An internal hot air circulation path is constructed based on the axial heat convection holes pre-drilled on the first-stage large gear. The heat generated in the primary meshing zone is physically thermally isolated from the secondary cycloidal pinwheel by the internal hot airflow circulation path, and the heat is then discharged.

2. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting as described in claim 1, characterized in that, The process of uniformly distributing the input load during the first-stage deceleration includes: Based on the two symmetrically distributed input pinions, the input load borne by each meshing point is reduced from F to F / 2; Calculate the contact stress at the meshing point after the flow split based on the reduced load F / 2. Contact stress at the meshing point after flow splitting , The contact stress at the engagement point before flow splitting; Based on the contact stress at the meshing point after flow splitting Calculate the frictional heat flux density per unit area The calculation formula is: in, The relative sliding speed, The coefficient of friction, is the conversion factor.

3. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power shunt as described in claim 1, characterized in that, The mathematical expression for the temperature field distribution is: in, This represents the heat source generated by two symmetrically distributed input pinions. This indicates the thermal conductivity of the material used in the reducer structure. Represents the Laplace operator. Represents the temperature field. This indicates the mass density of the material used in the reducer's structure. This indicates the specific heat capacity of the material used in the reducer's structure. Represents a time variable. This represents the transient rate of temperature rise over time.

4. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting as described in claim 1, characterized in that, During the manufacturing stage of the reducer, the standard tooth profile is pre-machined using a preset variable equidistant profile curve, leaving an initial clearance between the teeth. The expression for the variable equidistant profile curve is: in, This indicates the preset radial trimming amount, which is the thickness of metal that is pre-ground away during the reducer manufacturing stage; This represents the compensation correction coefficient, which is determined based on the linear expansion coefficient and rated temperature rise slope of the cycloidal wheel material, and is used to scale the compensation intensity. This represents the peak value of the maximum thermal deformation displacement calculated under rated operating conditions; This indicates the phase angle of the eccentric shaft rotation.

5. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power shunt as described in claim 4, characterized in that, Compensation correction coefficient The determination process includes: The thermo-elastic coupling displacement field of the cycloidal wheel during the entire phase period was obtained by using the finite element analysis method, and a least-squares objective function was established between the preset radial deformation and the actual thermal deformation. With minimizing the standard deviation of the full-phase meshing clearance as the optimization objective, the compensation correction coefficient is iteratively adjusted until the overlap between the actual tooth profile trajectory and the ideal tooth profile under hot conditions reaches the engineering design threshold, thus obtaining the optimal solution adapted to specific working conditions. value.

6. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting as described in claim 1, characterized in that, The formula for calculating thermo-elastic coupling deformation is: in, This represents the amount of thermo-elastic coupling deformation. It represents the rotation angle of the eccentric shaft, reflecting the phase of the meshing point in time or space; These represent the geometric characteristic parameters of the cycloidal pinwheel transmission mechanism. This indicates the maximum physical elastic contact deformation of the cycloidal pin teeth under rated load; This represents the radial thermal expansion displacement increment of the cycloidal wheel caused by a non-uniform temperature field under a specific temperature rise curve.

7. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power splitting as described in claim 6, characterized in that, Geometric characteristic parameters of cycloidal pinwheel transmission mechanism Defined as: ,in, This is the short amplitude coefficient.

8. The method for suppressing thermal deformation of a two-stage RV reducer based on dual-source power shunt as described in claim 1, characterized in that, The formula for calculating the axial convection heat transfer coefficient of the internal hot air circulation path is: in, It represents the axial convection heat transfer coefficient, used to reflect the heat dissipation rate; This represents the thermal conductivity of air. This represents the temperature distribution index, used to describe the radial distribution of temperature. The Prandtl number, representing air, is used to characterize the effect of fluid physical properties on heat transfer. This indicates the rotational angular velocity of the large first-stage gear; This indicates the kinematic viscosity of air.

9. A two-stage RV reducer based on dual-source power splitting, characterized in that, During operation, the reducer suppresses thermal deformation in accordance with the method described in any one of claims 1-8.

10. The two-stage RV reducer based on dual-source power splitting as described in claim 9, characterized in that, The reducer includes a primary flow splitting reduction mechanism and a secondary eccentric transmission mechanism; The primary flow divider deceleration mechanism includes a primary large gear and two input small gears; the two input small gears are symmetrically distributed around the primary large gear and drive the primary large gear to rotate; multiple axial heat convection holes are opened on the web of the primary large gear. The secondary eccentric transmission mechanism includes three evenly distributed eccentric shafts driven by a primary large gear. Each eccentric shaft is fitted with a cycloidal wheel, and an initial clearance is reserved between the tooth profiles of the cycloidal wheels.

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