Parking peak torque-based electric drive reduction gearbox shell impact checking method and system

Abstract

This invention discloses a method and system for impact verification of an electric drive gearbox housing based on parking peak torque. The method involves establishing a one-dimensional dynamic simulation model that includes the overall vehicle dynamics environment and the gearbox parking system; configuring parking conditions within the simulation model; running the simulation model with the parking conditions to obtain the parking peak torque of the parking system during the locking process under the corresponding parking conditions; converting the parking peak torque into impact forces acting on various components within the gearbox housing; and using these impact forces as input loads, importing them into the finite element simulation model of the gearbox housing for transient dynamic analysis to verify the impact on the gearbox housing. This invention improves the response accuracy of housing verification to multi-degree-of-freedom nonlinear dynamic impacts, shortens the development cycle, and reduces verification costs.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle transmission system design technology, specifically relating to a method and system for impact verification of electric drive gearbox housing based on parking peak torque. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the trends of miniaturization, integration, electrification, and intelligence of vehicle systems are becoming increasingly prominent, placing higher demands on vehicle safety performance. As a key component of electric vehicle safety, the parking system must be designed to balance simplicity, reliability, and high durability. The peak torque of the parking system is the core basis for its design and verification, and also an important foundation for assessing the impact strength of the gearbox housing.

[0003] Currently, there are certain shortcomings in the verification of gearbox housings: relying on static parking torque input, it can only calculate the torque under steady-state conditions based on theoretical formulas, and cannot cover the peak torque evolution process under different parking conditions; the verification time is delayed, and it needs to be verified by physical tests (such as bench impact tests) after the prototype is formed. If the housing strength is insufficient, it needs to be redesigned, which will lead to an extension of the R&D cycle and cannot meet the engineering requirements of rapid iteration of electric vehicles.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the aforementioned background technology by providing a method and system for impact verification of electric drive gearbox housing based on parking peak torque. This method can accurately obtain the parking peak torque under dynamic parking conditions, thereby accurately evaluating the impact strength of the gearbox housing.

[0006] The technical solution adopted in this invention is: a method and system for impact verification of an electric drive reduction gearbox housing based on parking peak torque, comprising the following steps: Establish a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system; Configure parking conditions in the dynamic simulation model; Run a dynamic simulation model configured with parking conditions to obtain the peak parking torque of the parking system during the locking process under the corresponding parking conditions; The parking peak torque is converted into impact force acting on various components inside the gearbox housing; The impact force is used as an input load and imported into the finite element simulation model of the gearbox housing for transient dynamic analysis, thereby verifying the impact on the gearbox housing.

[0007] Furthermore, the dynamic simulation model includes at least the parking system, driver system, control unit system, body system, tire and road system, housing and suspension system, motor system, gearbox system, half-shaft system, and parking system.

[0008] Furthermore, the parking conditions include any one or more of the following: parking on a flat road, parking on a slope, and parking in P gear when being hit.

[0009] Furthermore, the parking peak torque includes a high-frequency vibration torque component and a low-frequency vibration torque component. The high-frequency vibration torque component is generated by the inertial impact of the rotating parts inside the gearbox, corresponding to the time period within t1 after the start of the locking process; The low-frequency vibration torque component is generated by the head-up and head-down motion of the vehicle body, corresponding to the time period after time t1 after the start of the locking process; Where t1 is the time threshold after the start of the locking process, and its value is 0.1-0.3s.

[0010] Furthermore, the conversion of the parking peak torque into impact forces acting on various components within the gearbox housing includes: Obtain the moment of inertia of the rotating parts inside the gearbox and the transmission ratio from the rotating parts to the parking ratchet; Based on the moment of inertia and transmission ratio, the first acceleration torque caused by the high-frequency vibration torque component and the second acceleration torque caused by the low-frequency vibration torque component are calculated respectively. The original high-speed impact load acting on the rotating components inside the gearbox is calculated based on the first acceleration torque. The original low-frequency impact load acting on the gearbox housing and mounting structure is calculated based on the second acceleration torque. The original high-speed impact load and the original low-frequency impact load are combined into a dynamic load spectrum that varies with time, which is used as the impact force acting on the shell.

[0011] Furthermore, it also includes performing the following preload processing operation on the original high-speed impact load: Extract the axial force component of the original high-speed impact load; If the axial force component is less than the bearing preload, the bearing preload is used as a constant offset and superimposed with the axial force component to obtain the high-speed total axial force. The bearing preload is the preset axial clamping force during bearing installation. The high-speed total axial force is combined with the radial force component of the original high-speed impact load to obtain a first composite load vector, and the original high-speed impact load in the corresponding time period in the dynamic load spectrum is replaced by the first composite load vector.

[0012] Furthermore, it also includes performing the following preload processing operation on the original low-frequency impact load: Extract the axial force component of the original low-frequency impact load; If the parking torque corresponding to the original low-frequency impact load is greater than 50% of the rated torque, the bearing preload is deducted from the axial force component as a cancellation term to obtain the total low-frequency axial force. The low-frequency total axial force is combined with the radial force component of the original low-frequency impact load to obtain a second composite load vector, and the original low-frequency impact load in the corresponding time period in the dynamic load spectrum is replaced by the second composite load vector.

[0013] Furthermore, the boundary conditions for the transient dynamic analysis include: Simplify the housing mounting surface by fixing constraints or applying bolt preload; The coefficient of friction for the surface-to-surface contact between the housing and the end cap is defined as 0.1-0.2.

[0014] Furthermore, after performing transient dynamic analysis, the process also includes: A verification report is generated based on the simulation results, and the parking system stiffness, suspension stiffness, or vehicle parameters are adjusted based on parameter sensitivity analysis to optimize parking impact performance.

[0015] A system for implementing the above-described method for impact verification of an electric drive gearbox housing based on parking peak torque, comprising: The model building module is used to build a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system. The operating condition configuration module is used to configure parking operating conditions in the dynamic simulation model. The torque acquisition module is used to run a dynamic simulation model configured with parking conditions to acquire the peak parking torque of the parking system during the locking process under the corresponding parking conditions. The impact force conversion module is used to convert the parking peak torque into impact force acting on various components inside the gearbox housing; The shell verification module is used to take the impact force as an input load and import it into the finite element simulation model of the gearbox shell for transient dynamic analysis, so as to realize the verification of the impact on the gearbox shell.

[0016] The beneficial effects of this invention are as follows: This invention achieves precise capture of the dynamic evolution of peak parking torque during locking by configuring parking conditions in a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system. By using transmission ratio mapping and dynamic conversion, the torque is converted into transient impact force acting on the housing bearing seat, and the impact strength of the housing is quantified by combining finite element transient analysis. This improves the response accuracy of the housing verification to multi-degree-of-freedom nonlinear dynamic impacts, shortens the development cycle, and reduces verification costs. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but these descriptions do not constitute a limitation on the present invention.

[0019] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0020] Furthermore, references to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0021] like Figure 1 As shown, this application proposes a method for impact verification of the electric drive gearbox housing based on the peak parking torque. Establish a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system; Configure parking conditions in the dynamic simulation model; Run a dynamic simulation model configured with parking conditions to obtain the peak parking torque of the parking system during the locking process under the corresponding parking conditions; The parking peak torque is converted into impact force acting on various components inside the gearbox housing; The impact force is used as an input load and imported into the finite element simulation model of the gearbox housing for transient dynamic analysis, thereby verifying the impact on the gearbox housing.

[0022] Among them, the one-dimensional dynamic simulation model refers to a simplified mathematical model that can capture the main dynamic behavior of the system. This model integrates the vehicle dynamic environment with the gearbox parking system to simulate the vehicle's motion response and mechanical behavior under specific conditions, so as to quickly obtain the performance parameters of the parking system.

[0023] Parking conditions describe the various external conditions and internal operations that a vehicle may encounter while parked. These conditions cover scenarios such as the vehicle being stationary, the parking system being activated, and potential external disturbances, such as the vehicle being parked on a flat surface or a slope, or being subjected to an external collision while parked.

[0024] Peak parking torque refers to the maximum instantaneous torque experienced by the parking mechanism during the locking process of the parking system. This torque is a key parameter for evaluating the strength of the parking system and the impact load on the gearbox housing, reflecting the maximum stress generated within the structure at the moment of locking. Impact force refers to the instantaneous load converted from the peak parking torque and acting on the gearbox housing and its internal components. This force has a large amplitude and a short duration, and is the main cause of instantaneous stress, strain, and deformation in the housing structure.

[0025] A finite element method (FEM) simulation model refers to a computer model that discretizes the gearbox housing into a large number of interconnected finite elements and uses numerical methods to solve its mechanical response. This model can accurately simulate the geometry, material properties, and boundary conditions of the housing, thereby analyzing its stress distribution and deformation under complex loads. The finite element model is established by simplifying the CAD model of the housing. The simplification process involves removing non-critical chamfers and process holes (small chamfers, bolt holes, process grooves) to avoid increasing the computational load due to excessive mesh density, while retaining features such as bearing seat holes, reinforcing ribs, and casting fillets to reflect the true stress distribution. At the same time, material properties need to be defined. For gray cast iron or ductile iron, the first strength theory is used for verification.

[0026] Transient dynamic analysis is a simulation method used to study the dynamic response of a structure under time-varying loads. This analysis considers the inertial and damping effects of the structure and can capture the instantaneous stress, vibration, and deformation of the housing under impact loads, thereby evaluating its dynamic strength and durability. Gearbox housing impact verification refers to the process of evaluating, through simulation analysis or experimental verification, whether the gearbox housing meets the design strength and durability requirements under impact loads caused by peak parking torque. This verification aims to ensure that the housing will not fail under extreme operating conditions, guaranteeing vehicle operational safety.

[0027] This application establishes a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system, and configures parking conditions to obtain the dynamic parking peak torque of the parking system during the locking process. This dynamic torque is converted into impact force and imported into a finite element model for transient dynamic analysis, thus achieving accurate verification of the impact performance of the electric drive gearbox housing under complex parking conditions. This avoids the problems of long testing cycles and high costs associated with traditional experimental verification, and improves the efficiency and reliability of electric vehicle parking system design.

[0028] In one embodiment, this application further proposes that the dynamic simulation model is established in ITI-SimulatioanX software and includes at least a parking condition system, a driver system, a control unit system, a body system, a tire and road system, a housing and suspension system, a motor system, a gearbox system, a half-shaft system, and a parking system.

[0029] Specifically, the parking condition system is used to define the specific environmental conditions when a vehicle is parked, such as flat roads, slopes, or external impacts, providing accurate initial and boundary conditions for simulation.

[0030] The driver system simulates the maneuvers a driver might perform during parking, such as braking and shifting gears, to more realistically reflect the vehicle's dynamic state before the parking lock is engaged.

[0031] The control unit system represents the vehicle's electronic control unit, which is responsible for managing and coordinating key functions such as parking brake and motor torque output. Its control strategy directly affects the response characteristics of the parking system.

[0032] The vehicle body system transmits power from the powertrain to the tires and road system, simulating the vehicle's mass, inertia, and dynamic responses such as pitch and roll that may occur when the vehicle is locked in parking mode. The body system is constructed based on vehicle dynamics equations, considering slope resistance, acceleration resistance, rolling resistance, and air resistance. Slope resistance is determined by the vehicle's mass and road gradient; air resistance is determined by the drag coefficient, frontal area, and acceleration; acceleration resistance is determined by the vehicle's rotational mass conversion factor and acceleration; and rolling resistance is determined by the tire rolling resistance coefficient, vehicle mass, and road gradient. Specifically, rotational elements, linear elements, stiffness elements, mass elements, constraint elements, and lever elements from the SimulationX model library are used to simulate the forces and motion of the vehicle body. The rear-end collision module is simulated using collision elements and mass elements.

[0033] The tire-road system simulates the interaction between the tire and the road surface, including friction, slip characteristics, and road surface unevenness. These factors determine the mechanical coupling between the vehicle and the external environment. The construction of the tire-road system includes the overall mass of the wheel, the moment of inertia of the wheel hub, the moment of inertia of the wheel and tire, the damping and stiffness of the wheel and tire, and the tire-ground contact model; the tire-ground contact model uses the magic formula to describe the dynamic characteristics of the tire.

[0034] The housing and suspension system describes the gearbox housing and its connection methods and stiffness characteristics with the parking system and body system, and is a key link in the impact load transmission path. The housing and suspension system is constructed based on the stiffness matrix model of the housing and the damping and stiffness parameters of the suspension. Specifically, the rotational elements, mass elements, stiffness elements, and elastic elements in the SimulationX model library are used to simulate the force and motion state of the housing and suspension system.

[0035] The motor system simulates the characteristics of an electric drive system, including its rotational inertia and torque output capability. During parking and locking, the motor may still be in a certain working state or its inertia may contribute to the dynamic response of the system.

[0036] The gearbox system is the core component for generating and transmitting peak parking torque. The stiffness, damping, and inertia characteristics of its internal gears, bearings, and other components are crucial to the impact response. The gearbox system is constructed based on the rotational inertia of the input shaft, the damping and stiffness of the input shaft, the speed ratio of the first-stage gear pair, the rotational inertia of the first-stage gear pair, the damping and stiffness of the intermediate shaft, the rotational inertia of the intermediate shaft, the speed ratio of the second-stage gear pair, and the rotational inertia of the differential assembly. Specifically, the rotational elements, gear elements, stiffness elements, and elastic elements in the SimulationX model library are used to simulate the force and motion states of the gearbox system.

[0037] The half-shaft system connects the gearbox and the wheels, and its stiffness and inertia characteristics affect torque transmission and energy dissipation. The half-shaft system is constructed based on the damping and stiffness parameters of the half-shaft corresponding to the parking system. Specifically, the rotational elements, stiffness elements, and elastic elements in the SimulationX model library are used to simulate the force and motion state of the half-shaft system.

[0038] The parking system is the actuator that achieves parking lock. The stiffness, clearance, and dynamic characteristics of its locking mechanism directly determine the magnitude and waveform of the parking peak torque. The parking system is constructed by selecting the ratchet and pawl model and the gearbox shaft system connection interface based on the distribution of the parking system. The construction of the parking system is based on the number of teeth and backlash of the parking ratchet and pawl, as well as the damping and stiffness of the parking system. Specifically, the SimulationX model library is used to simulate the ratchet and pawl connection and the force and motion state of the parking system through rotary units, gear units, elastic units, damping units, and clearance units.

[0039] The stiffness of the parking system is determined using finite element analysis (FEA). For example, the gearbox model (including housing, shafts, gears, and bearings) is analyzed in Abaqus or Hypermesh. During the analysis, the pawl is fixed, and a torque of 10,000 Nm is applied to the ratchet. By measuring the angular displacement generated by the ratchet, the stiffness of the parking system can be calculated based on the ratchet angle and the applied torque.

[0040] The results show that the system is used to monitor real-time data from the system simulation; the data processing system is used for data processing, storage, and transmission; and the report generation system is used to generate simulation reports on the peak torque during parking. The parking condition system is communicatively connected to the driver system; the driver system is communicatively connected to the control unit system; the control unit system is communicatively connected to the parking system and the body system; the body system is communicatively connected to the half-shaft system, the housing and suspension system, and the tire and road system; the parking system is communicatively connected to the result display system, the housing and suspension system, and the reduction gearbox system; the reduction gearbox system is communicatively connected to the half-shaft system, the parking system, and the motor system; the result display system is communicatively connected to the parking system, the motor system, the body system, and the data processing system; and the data processing system is communicatively connected to the result display system and the report generation system.

[0041] The dynamic simulation model of this application can more comprehensively capture the complex dynamic coupling relationship between various components of the vehicle during the parking lock process. The obtained parking peak torque will be closer to the actual working condition. Both high-frequency vibration torque components and low-frequency vibration torque components can be predicted more accurately. This provides a more reliable input for converting the parking peak torque into the impact force acting on various components of the gearbox housing. As a result, the transient dynamic analysis and impact verification results of the gearbox housing are more instructive and have more practical engineering value, thus improving the reliability of the electric drive gearbox housing design.

[0042] In one embodiment, this application further proposes that the parking conditions include any one or more of the following: parking on a flat road, parking on a slope, and parking in P gear after a collision.

[0043] Specifically, flat road parking refers to the condition in which a vehicle is parked on a level road surface. In simulation, it is mainly used to evaluate the locking performance of the parking system under ideal conditions and the resulting impact. It can simulate the impact when a driver shifts into P gear on a flat road.

[0044] Hill start parking refers to the parking operation of a vehicle on a road surface with a certain slope. Simulations need to consider the effect of gravity along the slope on the vehicle, which increases the load on the parking system and may lead to more severe locking shocks. The slope can be set to different angles, such as 5%, 10%, and 15%, to simulate different levels of hill start parking conditions, helping to evaluate the impact response of the gearbox housing under additional gravitational loads.

[0045] The Parking (P) collision scenario refers to a situation where a vehicle, while in Parking (P), is subjected to a collision or impact from an external vehicle. This is an extreme but realistic scenario. The simulation needs to mimic the external impact force acting on the vehicle and transmitted through the transmission system to the parking system and gearbox housing. This involves transient, high-energy impact loads, posing a severe challenge to the structural integrity of the gearbox housing. Scenarios with different collision speeds, angles, and locations can be simulated to comprehensively evaluate the housing's impact resistance. By selecting any one or more of the above parking scenarios for configuration, the verification method can be adapted to different design stages and verification requirements.

[0046] The following is a detailed description of the operation process under the three typical parking conditions mentioned above: Parking on a flat road: This simulates a scenario where a target vehicle begins to park on a flat, straight road while creeping at a low speed (generally 3 km / h by default). First, the vehicle speed is converted into motor input speed using the reduction gear ratio and tire parameters. The accelerator and brake pedal signals from the driver's system are both 0, indicating the vehicle is in a coasting deceleration process. The control unit sends a P-gear activation signal, locking the parking pawl and parking gear. The vehicle rapidly decelerates, then oscillates back and forth until it comes to a complete stop. The peak torque generated during the process of engaging P-gear until the vehicle comes to a complete stop is the peak torque of the vehicle under the flat road parking condition. The results display system records and saves the vehicle's speed curve and the peak torque curve of the parking system, as well as the maximum positive and maximum negative torque of the parking system during this stage.

[0047] Hill Start Parking Condition: When the target vehicle is stationary on a slope at a certain angle (generally a maximum angle of 32%), the initial brake pedal signal is 1. At this moment, the control unit system sends a signal to engage P gear, locking the parking pawl and parking ratchet. Subsequently, the control unit system sends an action signal to reduce the brake pedal signal to 0. During the vehicle's rollback after the brake is released, the parking pawl and parking gear begin to interact. Due to gravity, the vehicle will sway back and forth until it comes to a complete stop on the slope. The peak torque generated during this process is the peak torque of the entire vehicle during hill start parking. The results display subsystem records and saves the vehicle's speed curve and the peak torque curve of the parking system, as well as the maximum positive and maximum negative torque of the parking system during this stage.

[0048] Parking in P gear and being hit: On a straight road, the target vehicle is stationary, with both the accelerator and brake pedal signals at 0. The control unit issues a command to engage P gear, locking the parking pawl and parking ratchet. A vehicle of a certain mass rear-ends the target vehicle at an initial velocity, causing a torque impact on the parking system. The peak torque generated during this process is the peak torque of the parking system in P gear and being hit. The results display subsystem records and saves the vehicle's speed curve and the parking system's peak torque curve, as well as the maximum positive and maximum negative torque of the parking system during this phase.

[0049] Through the above technical solution, this application refines the parking conditions into any one or more of the following: parking on a flat road, parking on a slope, and being hit in P gear. This allows the simulation model to more comprehensively and realistically reflect the impact loads that the vehicle experiences under different actual parking scenarios. This multi-condition configuration ensures that the gearbox housing can meet the impact strength requirements under various complex and extreme conditions, thereby improving the accuracy and reliability of the verification results and reducing the risk of product failure due to impact loads in actual use.

[0050] In one embodiment, this application further proposes that the parking peak torque is not a single static value, but rather includes high-frequency vibration torque components and low-frequency vibration torque components. This decomposition process aims to more precisely capture the complexity of the dynamic load during parking locking, providing more accurate input for subsequent impact force conversion and verification.

[0051] Specifically, the high-frequency vibration torque component is mainly generated by the inertial impact of rotating components inside the gearbox. When the parking system suddenly locks, the gears, shafts, and other rotating components inside the gearbox generate instantaneous high-frequency impact loads due to inertia. This high-frequency impact typically occurs within time t1 after the start of the locking process, manifesting as a short and intense energy release. Meanwhile, the low-frequency vibration torque component is mainly generated by the vehicle's pitching motion. After the parking system locks, the vehicle as a whole may experience periodic low-frequency vibrations due to inertia or terrain gradient, i.e., pitching motion. This motion is transmitted to the gearbox through the transmission system, forming a relatively continuous and low-frequency torque load, typically corresponding to the period after time t1 after the start of the locking process. Here, t1 is defined as the time threshold after the start of the locking process, used to distinguish the dominant phases of the high-frequency and low-frequency vibration torque components. The time threshold ranges from 0.1 to 0.3 seconds. It is a reasonable range determined empirically based on a large amount of simulation analysis and experimental data. It can effectively divide the instantaneous inertial impact and the subsequent low-frequency vibration of the vehicle body in time. The preferred value is 0.2 seconds.

[0052] Through the above technical solution, this application decomposes the peak parking torque into two vibration torque components with different characteristics: high-frequency and low-frequency, and clarifies their physical sources and temporal distribution. This refined torque decomposition method can more accurately reflect the true dynamic load spectrum borne by the gearbox housing during parking locking. This allows for more precise simulation of the stress response and deformation of the housing under loads of different frequencies and durations when the impact force is subsequently introduced as an input load into the finite element simulation model of the gearbox housing for transient dynamic analysis. This improves the accuracy and reliability of the gearbox housing impact verification and provides stronger data support for the structural optimization design of the gearbox.

[0053] In one embodiment, this application further proposes a method for converting the parking peak torque into impact forces acting on various components within the gearbox housing, specifically including the following steps: Obtain the moment of inertia of the rotating parts inside the gearbox and the transmission ratio from the rotating parts to the parking ratchet; Based on the moment of inertia and transmission ratio, the first acceleration torque caused by the high-frequency vibration torque component and the second acceleration torque caused by the low-frequency vibration torque component are calculated respectively. The original high-speed impact load acting on the rotating components inside the gearbox is calculated based on the first acceleration torque. The original low-frequency impact load acting on the gearbox housing and mounting structure is calculated based on the second acceleration torque. The original high-speed impact load and the original low-frequency impact load are combined into a dynamic load spectrum that varies with time, which is used as the impact force acting on the shell.

[0054] Specifically, moment of inertia refers to the ability of rotating components (such as gears and shafts) within a gearbox to resist changes in their rotational state. The transmission ratio refers to the proportion of angular velocity or torque transmitted from a specific rotating component to the parking ratchet; its value can be directly obtained from the gearbox's design parameters. These parameters form the basis for subsequent accurate calculations of impact loads at different frequencies.

[0055] High-frequency vibration torque components typically originate from the inertial impact of rotating components inside the gearbox at the moment of parking lock. Their duration is short and their frequency is high. Low-frequency vibration torque components are mainly generated by the continuous vibration of the entire vehicle system (such as the body's pitching and rolling motion after parking lock). Their duration is relatively long and their frequency is low. The first acceleration torque is the instantaneous torque caused by the high-frequency vibration torque component on the internal rotating components. Its calculation requires equivalenting of the high-frequency component of the parking peak torque to the corresponding rotating component through the transmission ratio, and combining this with its moment of inertia, using dynamic principles (e.g., torque equals moment of inertia multiplied by angular acceleration) to deduce it. The second acceleration torque is the torque caused by the low-frequency vibration torque component on the gearbox housing and mounting structure. Its calculation requires equivalenting of the low-frequency component of the parking peak torque to the gearbox housing and mounting structure through the transmission ratio, and considering its overall inertia and stiffness characteristics.

[0056] The original high-speed impact load refers to the instantaneous impact force caused by the high-frequency vibration torque component, acting on rotating components such as gears and bearings inside the gearbox. In the calculation, the initial acceleration torque is converted into forces and torques acting on these components through gear meshing forces, bearing reaction forces, etc., which usually involves detailed mechanical dynamics analysis, considering the contact stiffness of gears, the support characteristics of bearings, etc.

[0057] The original low-frequency impact load refers to the force caused by the low-frequency vibration torque component that acts on the gearbox housing and its mounting structure connected to the vehicle body. In the calculation, the second acceleration torque is converted into force and torque acting on the housing mounting point through the connection stiffness, damping and other characteristics of the gearbox housing and the mounting point. It usually involves the vibration analysis of the whole vehicle or subsystem.

[0058] A dynamic load spectrum is a force or torque curve that varies over time, integrating impact loads of different frequencies and amplitudes. By superimposing or combining the original high-speed impact load and the original low-frequency impact load in the time domain, a more comprehensive and realistic load spectrum can be obtained. This involves signal processing techniques such as Fourier transform and time-domain superposition to ensure the correct combination of different frequency components.

[0059] Through the above technical solution, this application can decompose the complex parking peak torque into two vibration torque components with different characteristics: high frequency and low frequency, and calculate their corresponding impact loads separately. This refined processing method allows for the accurate identification and quantification of the original high-speed impact load acting on the rotating components inside the gearbox and the original low-frequency impact load acting on the gearbox housing and mounting structure. Finally, these loads with different characteristics are combined into a dynamic load spectrum that varies with time, which is used as input to the finite element simulation model. This improves the accuracy and realism of the impact load spectrum, not only more accurately reflecting the stress state of the gearbox housing under different impact modes, but also providing a more reliable input for subsequent transient dynamic analysis. This ensures the accuracy and reliability of the gearbox housing impact verification results, thereby guiding the optimized design of the gearbox housing and improving its durability and safety under parking conditions.

[0060] In one embodiment, this application further proposes performing the following preload processing operation on the original high-speed impact load: Extract the axial force component of the original high-speed impact load; If the axial force component is less than the bearing preload, the bearing preload is used as a constant offset and superimposed with the axial force component to obtain the total high-speed axial force. The high-speed total axial force is combined with the radial force component of the original high-speed impact load to obtain a first composite load vector, and the original high-speed impact load in the corresponding time period in the dynamic load spectrum is replaced by the first composite load vector.

[0061] Specifically, the preload processing operation on the original high-speed impact load aims to correct the original high-speed impact load obtained from the dynamic simulation, making it more consistent with the stress conditions of the bearing under actual operating conditions. By introducing preload processing, the actual response of the bearing under impact load can be simulated more accurately, thereby improving the accuracy of subsequent transient dynamic analysis.

[0062] Extracting the axial force component of the original high-speed impact load means decomposing this three-dimensional force vector into its constituent parts along the bearing axis. Bearing preload is the axial force applied during installation to ensure bearing stiffness, reduce vibration, and improve rotational accuracy.

[0063] If the axial force component is less than the bearing preload, the bearing preload is used as a constant offset and superimposed with the axial force component to obtain the total axial force at high speed. This is because when the axial force component generated by external impact is insufficient to offset or exceed the bearing preload, the bearing actually still bears an axial force at least equal to the preload. Therefore, superimposing the bearing preload as a constant offset with the smaller axial force component can more accurately reflect the total axial force on the bearing under impact.

[0064] Subsequently, the total high-speed axial force is combined with the radial force component of the original high-speed impact load to obtain the first composite load vector. After obtaining the corrected total high-speed axial force, it needs to be recombine with the radial force component of the original high-speed impact load that is not affected by the preload. This combination is usually achieved through vector synthesis to form a new composite load vector that better reflects the actual stress conditions.

[0065] Finally, the original high-speed impact load in the corresponding time period of the dynamic load spectrum is replaced with the first composite load vector. The dynamic load spectrum is a load sequence that changes over time. By replacing the original high-speed impact load with the first composite load vector after preloading in the corresponding time period, it can be ensured that the input load used in the subsequent transient dynamic analysis is corrected and closer to the actual working conditions.

[0066] Through the above technical solution, this application can fully consider the preload effect of the bearings inside the gearbox when converting the parking peak torque into impact force, which helps to improve the accuracy and reliability of the gearbox housing impact verification, provides more solid data support for gearbox design optimization, and thus effectively improves the durability and safety of the electric drive gearbox.

[0067] In one embodiment, this application further proposes performing the following preload processing operation on the original low-frequency impact load: Extract the axial force component of the original low-frequency impact load; If the parking torque corresponding to the original low-frequency impact load is greater than 50% of the rated torque, the bearing preload is deducted from the axial force component as a cancellation term to obtain the total low-frequency axial force. The low-frequency total axial force is combined with the radial force component of the original low-frequency impact load to obtain a second composite load vector, and the original low-frequency impact load in the corresponding time period in the dynamic load spectrum is replaced by the second composite load vector.

[0068] Specifically, the original low-frequency impact load primarily reflects the impact of the large inertial force on the gearbox housing and mounting structure caused by the vehicle's pitching and tilting motion during parking and locking. Preloading this load aims to more realistically simulate the influence of bearings on the transmission and distribution of impact forces under actual operating conditions. This preloading is typically performed before applying the load to the finite element model to ensure the accuracy of the simulation results. Preloading can include adjusting, superimposing, or canceling load components to reflect existing stresses or mechanical states within the structure.

[0069] The original low-frequency impact load is typically a three-dimensional force vector. The axial force component refers to the force along the bearing axis, which directly affects the bearing preload and the stress on the bearing housing. Bearing preload is the preload applied during bearing installation, designed to improve bearing stiffness and reduce vibration and noise. Under low-frequency impact loads, when the parking torque reaches a certain level (e.g., 50% of the rated torque), the bearing preload will partially offset the external axial impact force. This means that when an impact occurs, the bearing preload will first absorb or resist a portion of the impact force, thereby reducing the actual axial force transmitted to the housing. Therefore, subtracting the bearing preload as a offset from the original axial force component more accurately reflects the net axial force borne by the housing. This threshold (50% of the rated torque) is an empirical value designed to distinguish between minor impacts and larger impact conditions that may allow the bearing preload to be effectively utilized.

[0070] The radial force component refers to the force perpendicular to the bearing axis, primarily affecting the bearing's radial support and the housing's radial deformation. After preloading the axial force component, the processed low-frequency total axial force needs to be recombined with the original radial force component (which is typically not directly offset by the bearing preload) to form a more realistic second composite load vector. This composite load vector represents the actual impact load after bearing preload correction. Subsequently, this corrected load vector replaces the corresponding original low-frequency impact load in the dynamic load spectrum, ensuring that subsequent transient dynamic analysis can be based on a more accurate input load, thereby improving the reliability of the verification results.

[0071] By performing preload processing on the original low-frequency impact load, this application can more accurately simulate the actual impact load borne by the gearbox housing under parking conditions, making the load input into the finite element simulation model more consistent with the actual situation. This improves the accuracy and reliability of the gearbox housing impact verification results, and provides a more solid data foundation for subsequent structural optimization and design improvement.

[0072] In one embodiment, this application further proposes that the boundary conditions for the transient dynamic analysis include: Simplify the housing mounting surface by fixing constraints or applying bolt preload; The coefficient of friction for the surface-to-surface contact between the housing and the end cap is defined as 0.1-0.2.

[0073] Specifically, the housing mounting surface refers to the interface between the gearbox housing and other vehicle structures (such as the frame and suspension system). In transient dynamic analysis, the constraints at these connection points are crucial to the accuracy of the simulation results. Simplifying the housing mounting surface to a fixed constraint means that the mounting surface is completely restricted in all degrees of freedom, allowing no translation or rotation. This approach is suitable for simulating very rigid connections or for simplification at the beginning of the analysis to quickly obtain preliminary results. Applying bolt preload is a simulation method that more closely approximates reality. Bolt preload simulates the clamping force exerted by bolts on the connectors during assembly. This force affects the stiffness and frictional characteristics of the connection interface, and can more accurately reflect the stress and deformation of the housing under impact loads.

[0074] Meanwhile, the gearbox housing is typically composed of multiple components (such as the main housing and end caps) connected by bolts. When subjected to impact loads, the contact surfaces between these components may experience relative sliding or fretting, with friction playing a crucial role in energy dissipation and force transmission. The coefficient of friction is a parameter that measures the magnitude of the frictional force between two contacting surfaces. In finite element simulations, by setting surface-to-surface contact pairs on the contact surfaces of the housing and end caps and assigning them specific coefficients of friction (e.g., 0.1-0.2), the interaction of these components under impact loads can be simulated.

[0075] Through the above technical solution, this application can provide more realistic and accurate boundary conditions for the transient dynamic analysis of the gearbox housing. The precise boundary condition setting improves the reliability and accuracy of the transient dynamic analysis results, making the verification of stress, deformation and fatigue life of the gearbox housing under parking impact load more consistent with actual working conditions.

[0076] In one embodiment, this application further proposes that after performing transient dynamic analysis, a verification report is generated based on the simulation results, and the parking system stiffness, suspension stiffness, or vehicle parameters are adjusted based on parameter sensitivity analysis to optimize parking impact performance.

[0077] Specifically, after completing the transient dynamics analysis, a verification report is first generated based on the simulation results. This verification report is a systematic summary and presentation of the data obtained from the transient dynamics analysis, aiming to provide quantitative data on key performance indicators of the gearbox housing under parking impact conditions, such as structural strength, stress distribution, and deformation. The report may include information such as maximum stress value, maximum deformation, stress concentration area, and safety factor, and can be visually displayed through stress cloud diagrams, deformation cloud diagrams, and time-stress curves, thus providing engineers with a comprehensive and clear basis for evaluating whether the housing design meets the requirements. For example, the report may list the stress levels of key components such as bearing housings and mounting holes in detail and compare them with the allowable stress of the material.

[0078] Based on this, parameter sensitivity analysis is performed. Parameter sensitivity analysis is a method to assess how sensitive the system output (such as the maximum stress or deformation of the gearbox housing) is to changes in input parameters (such as parking system stiffness, suspension stiffness, or vehicle parameters). Its purpose is to identify the design parameters that have the most significant impact on parking impact performance, thereby providing direction for subsequent optimization work.

[0079] Based on the results of parameter sensitivity analysis, the parking system stiffness, suspension stiffness, or overall vehicle parameters can be adjusted in a targeted manner. Parking system stiffness refers to the overall rigidity of the parking mechanism (such as parking pawls, ratchets, parking cables, etc.), which can be adjusted by changing the materials, geometry, or structural design of these components. Suspension stiffness refers to the stiffness of the suspension system connecting the electric drive assembly to the vehicle body, which can be adjusted by selecting rubber materials of different hardness, changing the geometry or number of suspension mounts. Overall vehicle parameters involve the overall characteristics of the vehicle, such as body mass, center of gravity position, and suspension system parameters (spring stiffness, shock absorber damping), etc. These parameters affect the vehicle's attitude changes and vibration response when parked and locked, thus affecting the peak parking torque. Through iterative adjustment and simulation verification of these key parameters, the parking impact performance can ultimately be optimized.

[0080] Through the above technical solution, after completing the transient dynamic analysis of the gearbox housing, this application can not only obtain the verification results but also generate a detailed verification report, intuitively presenting key information such as the stress and deformation of the housing. By introducing parameter sensitivity analysis, it can systematically identify the parking system stiffness, suspension stiffness, or vehicle parameters that have a significant impact on parking impact performance. Based on this analysis result, these key parameters can be adjusted in a targeted manner, thereby elevating the simple verification process to a design optimization process. This method avoids blindly modifying design parameters, improves the efficiency and accuracy of design optimization, and ensures that the gearbox housing has superior strength, stiffness, and durability under parking impact conditions, effectively improving product reliability and development efficiency.

[0081] In one embodiment, this application also discloses a system for implementing the above-described method for impact verification of the electric drive gearbox housing based on parking peak torque, comprising: The model building module is used to build a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system. The operating condition configuration module is used to configure parking operating conditions in the dynamic simulation model. The torque acquisition module is used to run a dynamic simulation model configured with parking conditions to acquire the peak parking torque of the parking system during the locking process under the corresponding parking conditions. The impact force conversion module is used to convert the parking peak torque into impact force acting on various components inside the gearbox housing; The shell verification module is used to take the impact force as an input load and import it into the finite element simulation model of the gearbox shell for transient dynamic analysis, so as to realize the verification of the impact on the gearbox shell.

[0082] The model building module integrates the vehicle dynamics environment with the gearbox parking system to construct a one-dimensional dynamic simulation model, which can efficiently capture the dynamic response characteristics of the vehicle during parking. The operating condition configuration module supports setting scenarios such as parking on flat roads, parking on slopes, or being impacted in P gear, to cover diverse conditions in actual use. The torque acquisition module, after running the simulation model, accurately extracts the peak parking torque during the parking system's locking process. This torque includes high-frequency and low-frequency vibration torque components, corresponding to the dynamic characteristics at different time points after locking begins. The impact force conversion module, based on the rotational inertia and transmission ratio of the rotating components inside the gearbox, converts the peak parking torque into impact forces acting on various components within the housing, forming a dynamic load spectrum that varies over time. The housing verification module uses the converted impact force as input load and imports it into the finite element simulation model of the gearbox housing to perform transient dynamic analysis. By setting fixed constraints or bolt preload boundary conditions on the housing mounting surface and defining the friction coefficient between the housing and the end cover contact surface, it accurately verifies the impact strength of the housing.

[0083] This application realizes a complete technology chain from whole vehicle dynamic simulation to housing impact verification, which improves the reliability and development efficiency of gearbox housing design.

[0084] It should be noted that the information interaction and execution process between the above modules / units are based on the same concept as the method embodiments of this application. For details on their specific implementation process, functions, and technical effects, please refer to the method embodiments section, and they will not be repeated here. The descriptions of each embodiment have their own emphasis; parts not detailed or recorded in a certain embodiment can be referred to the relevant descriptions of other embodiments.

[0085] It is understood that those skilled in the art will clearly recognize that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application.

[0086] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0087] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application. Content not described in detail in this specification belongs to the prior art known to those skilled in the art.

Claims

1. A method for impact verification of an electric drive reduction gearbox housing based on parking peak torque, characterized in that: Establish a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system; Configure parking conditions in the dynamic simulation model; Run a dynamic simulation model configured with parking conditions to obtain the peak parking torque of the parking system during the locking process under the corresponding parking conditions; The parking peak torque is converted into impact force acting on various components inside the gearbox housing; The impact force is used as an input load and imported into the finite element simulation model of the gearbox housing for transient dynamic analysis, thereby verifying the impact on the gearbox housing.

2. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: The dynamic simulation model includes at least the parking system, driver system, control unit system, body system, tire and road system, housing and suspension system, motor system, gearbox system, half-shaft system, and parking system.

3. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: The parking conditions include any one or more of the following: parking on a flat road, parking on a slope, and parking in P gear after a collision.

4. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: The parking peak torque includes high-frequency vibration torque components and low-frequency vibration torque components. The high-frequency vibration torque component is generated by the inertial impact of the rotating parts inside the gearbox, corresponding to the time period within t1 after the start of the locking process; The low-frequency vibration torque component is generated by the head-up and head-down motion of the vehicle body, corresponding to the time period after time t1 after the start of the locking process.

5. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: The process of converting the parking peak torque into impact forces acting on various components within the gearbox housing includes: Obtain the moment of inertia of the rotating parts inside the gearbox and the transmission ratio from the rotating parts to the parking ratchet; Based on the moment of inertia and transmission ratio, the first acceleration torque caused by the high-frequency vibration torque component and the second acceleration torque caused by the low-frequency vibration torque component are calculated respectively. The original high-speed impact load acting on the rotating components inside the gearbox is calculated based on the first acceleration torque. The original low-frequency impact load acting on the gearbox housing and mounting structure is calculated based on the second acceleration torque. The original high-speed impact load and the original low-frequency impact load are combined into a dynamic load spectrum that varies with time, which is used as the impact force acting on the shell.

6. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 5, characterized in that: This also includes performing the following preload processing operation on the original high-speed impact load: Extract the axial force component of the original high-speed impact load; If the axial force component is less than the bearing preload, the bearing preload is used as a constant offset and superimposed with the axial force component to obtain the total high-speed axial force. The high-speed total axial force is combined with the radial force component of the original high-speed impact load to obtain a first composite load vector, and the original high-speed impact load in the corresponding time period in the dynamic load spectrum is replaced by the first composite load vector.

7. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 5, characterized in that: This also includes performing the following preload processing operation on the original low-frequency impact load: Extract the axial force component of the original low-frequency impact load; If the parking torque corresponding to the original low-frequency impact load is greater than 50% of the rated torque, the bearing preload is deducted from the axial force component as a cancellation term to obtain the total low-frequency axial force. The low-frequency total axial force is combined with the radial force component of the original low-frequency impact load to obtain a second composite load vector, and the original low-frequency impact load in the corresponding time period in the dynamic load spectrum is replaced by the second composite load vector.

8. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: The boundary conditions for the transient dynamics analysis include: Simplify the housing mounting surface by fixing constraints or applying bolt preload; The coefficient of friction for the surface-to-surface contact between the housing and the end cap is defined as 0.1-0.

2.

9. The method for impact verification of electric drive gearbox housing based on parking peak torque according to claim 1, characterized in that: After performing transient dynamic analysis, the process also includes: A verification report is generated based on the simulation results, and the parking system stiffness, suspension stiffness, or vehicle parameters are adjusted based on parameter sensitivity analysis to optimize parking impact performance.

10. A system for implementing the impact verification method for an electric drive gearbox housing based on parking peak torque as described in claim 1, characterized in that, include: The model building module is used to build a one-dimensional dynamic simulation model that includes the vehicle's dynamic environment and the gearbox parking system. The operating condition configuration module is used to configure parking operating conditions in the dynamic simulation model. The torque acquisition module is used to run a dynamic simulation model configured with parking conditions to acquire the peak parking torque of the parking system during the locking process under the corresponding parking conditions. The impact force conversion module is used to convert the parking peak torque into impact force acting on various components inside the gearbox housing; The shell verification module is used to take the impact force as an input load and import it into the finite element simulation model of the gearbox shell for transient dynamic analysis, so as to realize the verification of the impact on the gearbox shell.

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