A vacuum pump control system and method for pure electric vehicles

Abstract

This invention discloses a vacuum pump control system and method for a pure electric vehicle, belonging to the field of electric vehicle braking. The system includes a VCU (1), a brake pedal depth sensor (2), a pipeline pressure sensor (3), an atmospheric pressure sensor (4), a temperature sensor (5), a humidity sensor (6), a vacuum pump relay (7), a vacuum pump (8), a motor system (9), and an instrument system (10). The VCU (1) is connected to the brake pedal depth sensor (2), the pipeline pressure sensor (3), the atmospheric pressure sensor (4), the temperature sensor (5), the humidity sensor (6), the vacuum pump relay (7), the motor system (9), and the instrument system (10), respectively. The vacuum pump relay (7) is connected to the vacuum pump (8). This invention realizes the functions of environmental adaptation, performance degradation learning, energy recovery linkage, and early fault warning for vacuum pump control.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle braking. Specifically, this invention relates to a vacuum pump control system and method for a pure electric vehicle. Background Technology

[0002] Because new energy pure electric vehicles eliminate the traditional engine and transmission, the control of the brake vacuum booster system is based entirely on an electric vacuum pump, making the control of the vacuum pump particularly important. A reasonable braking system design and a complete and safe control system strategy are the foundation for the safe braking of a new energy pure electric vehicle.

[0003] The publication document with publication number CN114435328A and publication date of 2022-05-06 discloses a braking system and control method for a pure electric vehicle. Its purpose is to make the braking system control of pure electric vehicles more intelligent and safer, so as to effectively extend the service life of the vacuum pump. However, it uses a pressure threshold that is only related to atmospheric pressure to control the start and stop of the vacuum pump. This control strategy has limitations: it does not combine with the ambient temperature and humidity, and has low environmental adaptability.

[0004] Therefore, this invention proposes a vacuum pump control system and method for pure electric vehicles. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of the prior art and proposes a vacuum pump control system and method for pure electric vehicles to achieve the following objectives: realizing environmental adaptation, performance degradation learning, energy recovery linkage and early fault warning functions of vacuum pump control.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A vacuum pump control system for a pure electric vehicle includes a VCU1, a brake pedal depth sensor 2, a pipeline pressure sensor 3, an atmospheric pressure sensor 4, a temperature sensor 5, a humidity sensor 6, a vacuum pump relay 7, a vacuum pump 8, a motor system 9, and an instrument system 10. The brake pedal depth sensor 2, pipeline pressure sensor 3, atmospheric pressure sensor 4, temperature sensor 5, and humidity sensor 6 are each connected to the VCU1. The VCU1 is connected to the vacuum pump 8 via the vacuum pump relay 7. The VCU1 is connected to the motor system 9 and the instrument system 10 via a communication bus.

[0008] Preferably, the system further includes a data storage unit 11, which is connected to the VCU1.

[0009] Preferably, the system further includes a remote diagnostic interface 12, which is connected to the VCU1.

[0010] Preferably, the system is powered by a 12V battery.

[0011] Preferably, the VCU1 is connected to the motor system 9 and the instrument system 10 via a CAN bus.

[0012] The present invention also provides a vacuum pump control method for a pure electric vehicle, using the above-described vacuum pump control system for a pure electric vehicle, the control method comprising:

[0013] Step S1: VCU1 obtains the user-preset vacuum pump start-up pressure threshold and stop-down pressure threshold, wherein the start-up pressure threshold is greater than the stop-down pressure threshold;

[0014] Step S2: The atmospheric pressure, ambient temperature and humidity of the vehicle's current environment are collected in real time by the atmospheric pressure sensor 4, temperature sensor 5 and humidity sensor 6 and sent to the VCU1.

[0015] Step S3: Based on the atmospheric pressure, ambient temperature and humidity, VCU1 introduces a three-dimensional correction factor to dynamically correct the vacuum pump's opening pressure threshold and closing pressure threshold.

[0016] Step S4: The vehicle brake line pressure is acquired in real time through the line pressure sensor 3 and sent to the VCU1;

[0017] Step S5: VCU1 compares the real-time collected vehicle brake line pressure with the dynamically corrected vacuum pump opening pressure threshold and closing pressure threshold to determine whether to open or close the vacuum pump.

[0018] When the vacuum pump is in the off state, it will be turned on when the real-time collected vehicle brake line pressure is greater than or equal to the dynamically corrected opening pressure threshold; when the vacuum pump is in the on state, it will be turned off when the real-time collected vehicle brake line pressure is less than or equal to the dynamically corrected closing pressure threshold.

[0019] Preferably, based on the atmospheric pressure, ambient temperature, and humidity, a three-dimensional correction factor is introduced to dynamically correct the vacuum pump's start-up pressure threshold and stop-down pressure threshold, including:

[0020] The three-dimensional correction factor F is expressed as follows:

[0021] F = f(P, T, H);

[0022] Wherein, P represents atmospheric pressure; T represents ambient temperature; H represents ambient humidity; and f represents the mapping relationship between P, T, H and the three-dimensional correction factor F, which is stored in the form of a data mapping table.

[0023] Based on real-time collected atmospheric pressure P, ambient temperature T, and ambient humidity H, VCU1 obtains the corresponding three-dimensional correction factor F from the data mapping table using a lookup table method combined with an interpolation algorithm, and corrects the vacuum pump's start-up pressure threshold and stop-down pressure threshold. The formula is as follows:

[0024] P start-new =P start *F;P stop-new =P stop *F;

[0025] Among them, P start and P stop These represent the vacuum pump start-up pressure threshold and stop-down pressure threshold before correction, respectively; P start-new and P stop-new These represent the corrected vacuum pump start-up pressure threshold and shut-off pressure threshold, respectively.

[0026] Preferably, the control method further includes: introducing a vacuum pump performance degradation modeling and compensation mechanism, that is, VCU1 periodically performs the following operations:

[0027] • Calculate the time t required for the vacuum pump to reach the preset pressure from startup in n consecutive cycles;

[0028] • Calculate the average value of bar{t} of the time t required for the vacuum pump to reach the preset pressure from start-up for n consecutive cycles;

[0029] • If bar{t} > t0, where t0 represents a preset time threshold, then the pump body is determined to be aging, and the compensation mode is automatically activated, including:

[0030] • Reduce the vacuum pump's start-up pressure threshold;

[0031] • Lower the vacuum pump shutdown pressure threshold;

[0032] The instrument system 10 sends a vacuum pump maintenance reminder to the user.

[0033] Preferably, the control method further includes: VCU1, in conjunction with the motor system 9, utilizes the vehicle deceleration characteristics during regenerative braking to predict braking vacuum requirements in advance.

[0034] When VCU1 receives a motor braking request from the motor system 9 and detects through the brake pedal depth sensor 2 that the current braking intensity is greater than the preset first braking intensity threshold: in the vacuum pump off state, the vacuum pump is started in advance by reducing the vacuum pump start pressure threshold;

[0035] If VCU1 detects through the motor system 9 that the brake pedal depth sensor 2 detects that the current braking intensity is greater than 0 after the motor braking request ends, then the vacuum pump will be turned off after a preset time delay, once the pipeline pressure is less than or equal to the vacuum pump shutdown pressure threshold.

[0036] Preferably, the control method further includes: introducing an early warning mechanism for vacuum pump failures, including:

[0037] The health index (HI) of a vacuum pump is calculated using the following formula:

[0038] ;

[0039] in, This indicates the current average evacuation time of the vacuum pump. This indicates the average vacuum pumping time at the time of manufacture. This indicates the rated number of start-stop cycles for the vacuum pump. This indicates the cumulative number of times the vacuum pump has actually started and stopped; This indicates the natural pressure relief rate of the vacuum pump per unit time. , , This represents the preset weighting coefficients, and , , The sum is 1;

[0040] Based on the calculated Vacuum Pump Health Index (HI), the health status of the vacuum pump is classified and corresponding intervention measures are taken.

[0041] The technical effects of this invention are as follows:

[0042] This invention utilizes the vehicle control unit (VCU) to fuse multi-source information, enabling environmental adaptive adjustment, aging compensation, early fault warning, and energy consumption optimization in the braking vacuum system. This significantly improves the system's safety, durability, and intelligence. It is applicable to various pure electric passenger vehicles, and is particularly suitable for use in high-altitude and complex climate environments. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of a vacuum pump control system for a pure electric vehicle, provided as an embodiment of the present invention. Detailed Implementation

[0044] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. This is to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solutions of the present invention, and to facilitate its implementation. It should be noted that the terms "first," "second," etc., used in this application are only for the convenience of describing the technical solutions and to distinguish components; the corresponding component configurations may be the same or different, and are not intended to limit the scope of this application. To make the technical solutions of the present invention clearer, the present invention will be explained and illustrated through the following embodiments.

[0045] This invention aims to propose a novel vacuum pump control system and its control method that integrates environmental adaptation, performance degradation learning, energy recovery linkage, and early fault warning functions, based on existing technologies, thereby solving the following problems:

[0046] (1) To achieve automatic correction of vacuum control parameters under different altitudes, temperatures and humidity conditions;

[0047] (2) Construct a vacuum pump performance degradation model to achieve life prediction and control compensation;

[0048] (3) Integrate the motor braking signal to optimize the start-stop timing of the vacuum pump and reduce ineffective power consumption;

[0049] (4) Provide an early fault warning mechanism to improve vehicle safety and user experience.

[0050] Therefore, this invention first proposes a vacuum pump control system for a pure electric vehicle, the schematic diagram of which is shown below. Figure 1 As shown. The system includes a VCU1 (vehicle controller), a brake pedal depth sensor 2, a pipeline pressure sensor 3, an atmospheric pressure sensor 4, a temperature sensor 5, a humidity sensor 6, a vacuum pump relay 7, a vacuum pump 8, a motor system 9, and an instrument system 10. The brake pedal depth sensor 2, pipeline pressure sensor 3, atmospheric pressure sensor 4, temperature sensor 5, and humidity sensor 6 are each connected to the VCU1. The VCU1 is connected to the vacuum pump 8 via the vacuum pump relay 7. The VCU1 is connected to the motor system 9 and the instrument system 10 via a communication bus.

[0051] In this embodiment, the vehicle controller (VCU1) is the core component of the control system, and other components receive control commands from the vehicle controller. Compared to existing technologies, in this embodiment, the vehicle controller (VCU1) has undergone an upgraded control algorithm, including environmental adaptive adjustment of vacuum pump start-up and shut-down pressure thresholds, performance degradation learning, energy recovery linkage, and early fault warning functions. In specific implementation, the vehicle controller (VCU1) achieves the normal operation of this upgraded control algorithm through data exchange with the vacuum pump, various sensors, and other vehicle systems (instrument system, motor system), thereby realizing environmental adaptive adjustment, aging compensation, early fault warning, and energy consumption optimization of the vacuum pump system.

[0052] Brake pedal depth sensor 2 is used to detect the brake pedal depth, which represents the user's braking intention. The data collected by the brake pedal depth sensor is an analog signal, which generates a linear voltage signal change as the brake pedal depth changes. By judging this voltage signal, the depth of the brake pedal can be indirectly sensed.

[0053] The pipeline pressure sensor 3 monitors the pressure in the vehicle's brake lines and sends it to the VCU1. The VCU1 can then determine whether the vacuum pump should start or stop based on the pipeline pressure. Additionally, in this embodiment, the VCU1 can control the vacuum pump's start and stop by opening and closing the vacuum pump relay 7. The atmospheric pressure sensor 4 monitors the atmospheric pressure at the vehicle's current location and can be used to determine the current altitude. Furthermore, compared to existing technologies, this embodiment also introduces a temperature sensor and a humidity sensor to detect the temperature and humidity data of the vehicle's current environment and send it to the VCU1. This allows the VCU1 to dynamically adjust the originally fixed vacuum pump start and stop pressure thresholds based on the current atmospheric pressure, ambient temperature, and ambient temperature.

[0054] The system in this embodiment of the invention further includes a data storage unit 11 (Flash / EEPROM), which is connected to the VCU1. The data storage unit 11 is used to record the system's operating data, especially vacuum pump operating data such as cumulative operating time, number of start-stop cycles, and historical pressure curves, to facilitate data traceability and application.

[0055] The system in this embodiment of the invention also includes a remote diagnostic interface 12, which is connected to the VCU1. Through the remote diagnostic interface 12, the VCU1 can communicate remotely with the cloud, thereby supporting the uploading of operational data to the cloud and enabling remote health assessment. Furthermore, the system can also perform remote over-the-air (OTA) upgrades on the vehicle controller VCU1 via the cloud, such as adjusting parameters in the control algorithm.

[0056] In this embodiment of the invention, the entire vacuum pump control system is powered by a 12V battery. This 12V battery provides power to the vehicle controller (VCU1), brake pedal depth sensor 2, pipeline pressure sensor 3, atmospheric pressure sensor 4, temperature sensor 5, humidity sensor 6, vacuum pump relay 7, and vacuum pump 8, thereby ensuring the normal operation of the system. As an independent low-voltage power supply system in the vehicle, the 12V battery provides power to the system in this embodiment even if the vehicle's high-voltage system is not working, ensuring system functionality. Furthermore, 12V battery technology is mature and standardized, facilitating replacement and maintenance, improving system convenience and reducing system costs.

[0057] In this embodiment of the invention, the vehicle controller VCU1 is connected to the motor system 9 and the instrument system 10 via a CAN bus, thereby establishing a communication connection between the vehicle controller VCU1 and other vehicle systems. The communication connection between VCU1 and the motor system 9 enables data exchange between them, allowing VCU1 to obtain information such as motor regenerative braking status and battery SOC uploaded by the motor system 9. The communication connection between VCU1 and the instrument system 10 enables data exchange between them, allowing VCU1 to perform human-machine interaction functions such as alarms and prompts through the instrument system 10.

[0058] The system of this embodiment retains the hardware configuration of the prior art, such as brake pedal depth sensor, vacuum pump relay, vacuum pump, pipeline pressure sensor, and atmospheric pressure sensor, and additionally introduces temperature sensor and humidity sensor for dynamic adjustment of the vacuum pump opening and closing pressure thresholds, realizing the environmental adaptive function of the system in this embodiment. At the same time, a large data storage unit 11 is introduced to record system working data, which facilitates data traceability and provides a historical data foundation for future upgrades of the control algorithm in VCU1. The system of this embodiment also introduces a remote diagnostic interface 12, realizing remote communication between the vehicle controller VCU1 and the cloud, which facilitates the cloud's diagnosis and upgrade of the vehicle controller VCU1.

[0059] This invention also provides a vacuum pump control method for a pure electric vehicle. Using the above-described vacuum pump control system for a pure electric vehicle, the control method includes the following steps:

[0060] Step S1: VCU1 obtains the user-preset vacuum pump start-up pressure threshold and stop-down pressure threshold, wherein the start-up pressure threshold is greater than the stop-down pressure threshold;

[0061] Step S2: The atmospheric pressure, ambient temperature and humidity of the vehicle's current environment are collected in real time by the atmospheric pressure sensor 4, temperature sensor 5 and humidity sensor 6 and sent to the VCU1.

[0062] Step S3: Based on the atmospheric pressure, ambient temperature and humidity, VCU1 introduces a three-dimensional correction factor to dynamically correct the vacuum pump's opening pressure threshold and closing pressure threshold.

[0063] Step S4: The vehicle brake line pressure is acquired in real time through the line pressure sensor 3 and sent to the VCU1;

[0064] Step S5: VCU1 compares the real-time collected vehicle brake line pressure with the dynamically corrected vacuum pump opening pressure threshold and closing pressure threshold to determine whether to open or close the vacuum pump.

[0065] When the vacuum pump is in the off state, it will be turned on when the real-time collected vehicle brake line pressure is greater than or equal to the dynamically corrected opening pressure threshold; when the vacuum pump is in the on state, it will be turned off when the real-time collected vehicle brake line pressure is less than or equal to the dynamically corrected closing pressure threshold.

[0066] Referring to step S1, before the entire system is applied, the vacuum pump's on-state pressure threshold and off-state pressure threshold need to be preset in advance. Under normal circumstances, the setting of the vacuum pump's on-state pressure threshold and off-state pressure threshold can refer to the atmospheric pressure of the vehicle's location, thereby compensating for the influence of altitude on the vacuum pump and determining the system's absolute pressure reference. For example, the vacuum pump's on-state pressure threshold can be set to 45%P, and the vacuum pump's off-state pressure threshold can be set to 25%P, where P represents the current atmospheric pressure. Simultaneously, different vacuum pump on-state pressure threshold and off-state pressure threshold schemes can be set based on vehicle speed. For example, in low-speed mode (speed < 80 km / h), the vacuum pump's on-state pressure threshold is set to 45%P, and the vacuum pump's off-state pressure threshold is set to 25%P; in high-speed mode (speed ≥ 80 km / h), the vacuum pump's on-state pressure threshold is set to 40%P, and the vacuum pump's off-state pressure threshold is set to 25%P. ​​In specific implementation, users can flexibly set the initial vacuum pump's on-state pressure threshold and off-state pressure threshold according to the actual situation.

[0067] However, the vacuum pump opening and closing pressure thresholds set in step S1 do not take into account ambient temperature and humidity. Temperature and humidity significantly affect the physical properties of air, the sealing performance of the vacuum system, and the working efficiency of the pump itself. Simply relying on atmospheric pressure is insufficient to guarantee the reliability and consistency of braking assistance under all environmental conditions.

[0068] Regarding temperature:

[0069] As temperature rises, air density decreases. Under the same absolute pressure, rarefied air contains fewer molecules, resulting in different actual workloads required for a vacuum pump to establish the same vacuum level. Thresholds need to be adjusted to optimize pump start-up and shutdown frequency and energy consumption. Low temperatures (such as -30°C) can cause vacuum pump sealing rubber parts to harden and shrink, potentially leading to leaks. More sensitive thresholds are needed to compensate for potential vacuum losses. At the same time, the viscosity of vacuum pump lubricating oil increases sharply at low temperatures, resulting in high pump start-up resistance, slow speed build-up, and reduced initial pumping capacity.

[0070] Regarding humidity:

[0071] Humid air contains a large amount of water vapor, which condenses into water or even ice on the surface of cryogenic components (such as vacuum lines and gas tanks). This can take up space, affect the accuracy of vacuum measurement, and may corrode or clog components. The system needs to adjust the threshold according to humidity to cope with this "false vacuum" variation and potential risks.

[0072] Therefore, the setting of the vacuum pump's opening and closing pressure thresholds requires consideration of not only atmospheric pressure but also ambient temperature and humidity. By linking these three factors, the VCU1 can more accurately determine when the vacuum pump needs to be activated for supplemental braking, ensuring that the driver receives a stable and reliable braking feel regardless of whether the environment is high-altitude, frigid, hot, or humid, while also optimizing pump lifespan and overall vehicle energy consumption.

[0073] Specifically, referring to steps S2 and S3, this embodiment of the invention uses an atmospheric pressure sensor 4, a temperature sensor 5, and a humidity sensor 6 to collect real-time data on the atmospheric pressure, ambient temperature, and humidity of the vehicle's current environment and send this data to the VCU1. Then, the VCU1 can dynamically correct the vacuum pump's opening and closing pressure thresholds based on the atmospheric pressure, ambient temperature, and humidity data, incorporating a three-dimensional correction factor. This includes:

[0074] The three-dimensional correction factor F is expressed as follows:

[0075] F = f(P, T, H);

[0076] Where P represents atmospheric pressure; T represents ambient temperature; H represents ambient humidity; and f represents the mapping relationship between P, T, H and the three-dimensional correction factor F. f is typically not a simple mathematical formula written in the code; in this embodiment, the mapping relationship is stored as a data mapping table. Subsequently, VCU1, based on the real-time collected atmospheric pressure P, ambient temperature T, and ambient humidity H, obtains the corresponding three-dimensional correction factor F from the data mapping table using a lookup table method combined with an interpolation algorithm. The three-dimensional correction factor F is then used to correct the preset vacuum pump start-up and stop-down pressure thresholds in step S1, as expressed by the following formula:

[0077] P start-new =P start *F;P stop-new =P stop *F;

[0078] Among them, P start and P stop These represent the vacuum pump start-up pressure threshold and stop-down pressure threshold before correction, respectively; P start-new and P stop-new These represent the corrected vacuum pump start-up pressure threshold and shut-off pressure threshold, respectively.

[0079] The effects of atmospheric pressure, temperature, and humidity on vacuum pump performance can be nonlinear and complex, and are determined through extensive experimental measurements. Engineers can then derive a series of optimal correction factors F by conducting tests under different environments (laboratory simulations of high altitudes, high temperatures, high humidity, etc.). These input-output pairs are then compiled into a three-dimensional (or higher-dimensional) data mapping table and stored in the VCU1. During real-time operation, after acquiring atmospheric pressure P, ambient temperature T, and ambient humidity H, the VCU1 can quickly find the corresponding correction factor F for the current environment by consulting this data mapping table.

[0080] For example, the VCU1 acquires the following set of atmospheric pressure P, ambient temperature T, and ambient humidity H: P = 70.0 kPa (low atmospheric pressure at high altitudes), T = 15℃, H = 85% (high humidity after rain). The VCU compares this set of data (P = 70.0 kPa, T = 15℃, H = 85%) with a preset data mapping table. If there is a precise correspondence between the current atmospheric pressure P, ambient temperature T, and ambient humidity H in the table, the corresponding correction factor F is directly read. However, in general, the collected data will not be exactly equal to the node values ​​in the table. Therefore, in this embodiment, the VCU1 uses an interpolation algorithm (such as three-dimensional linear interpolation) to estimate the correction factor F under the current environment based on the nearest correction factors F in the data mapping table, and then uses this correction factor F to correct the vacuum pump's start-up pressure threshold and stop-down pressure threshold.

[0081] For example, the correction factor F corresponding to the current environment (P = 70.0 kPa, T = 15℃, H = 85%) is 0.88;

[0082] The original vacuum pump start-up pressure threshold was:

[0083] P start = 45% * P = 45% * 70kPa = 31.5kPa;

[0084] Previous vacuum pump shut-off pressure threshold:

[0085] P stop = 25% * P = 25% * 70kPa = 17.5kPa;

[0086] Revised vacuum pump start-up pressure threshold:

[0087] P start-new = 31.5kPa * 0.88 = 27.7kPa;

[0088] Revised vacuum pump shutdown pressure threshold:

[0089] P stop-new = 17.5kPa * 0.88 = 15.4kPa.

[0090] If the system only uses atmospheric pressure-based vacuum pump start and stop pressure thresholds, in high-altitude, humid, and low-temperature environments, the vacuum pump may start too early and stop too late, leading to frequent start-stop cycles, increased power consumption, and accelerated wear. However, after adjusting with a three-dimensional correction factor F, an F=0.88 is introduced, indicating that the system recognizes the current environment is unfavorable for pumping efficiency. Therefore, it proactively lowers the operating requirements: allowing the vacuum level in the booster to be slightly lower (27.7 kPa) before starting the pump, and stopping it without reaching a lower vacuum level (15.4 kPa). Ultimately, the vacuum pump's single-cycle operating time is slightly longer, but the operating interval is significantly longer, avoiding unnecessary frequent start-stop cycles and achieving a more intelligent, durable, and energy-efficient operating strategy in complex environments.

[0091] In addition, in order to ensure sufficient braking vacuum assistance and driving safety even when the vacuum pump gradually ages and its pumping efficiency decreases, and to provide early warning of malfunctions, the control method of this embodiment of the invention also includes: introducing a vacuum pump performance degradation modeling and compensation mechanism, that is, VCU1 periodically performs the following operations.

[0092] Calculate the time t required for the vacuum pump to reach the preset pressure from startup in n consecutive cycles.

[0093] The average value of bar{t} is calculated for n consecutive vacuum pump cycles from start-up to preset pressure. The pumping time of a single vacuum pump cycle can be affected by random factors such as road conditions, usage frequency, and temperature, making single data unreliable. Therefore, this embodiment of the invention uses the method of taking the average value of multiple cycles to filter out random fluctuations and truly reflect the long-term and stable pumping capacity of the vacuum pump. Only when the average time increases can it be said that the pump efficiency has indeed declined or aged, rather than being a random fluctuation.

[0094] If bar{t} > t0, where t0 represents a preset time threshold, then the pump body is determined to be aging. The more aged the vacuum pump, the more internal wear, sealing deteriorates, and pumping speed decreases, resulting in a longer time to reach the target vacuum pressure. This embodiment of the invention uses time as the judgment criterion, requiring no additional sensors and relying solely on existing pressure signals and timing. This approach is low-cost and highly reliable. Reaching the preset time threshold indicates that the vacuum pump performance has deteriorated to a level that may affect the safety of brake assist, requiring intervention. Correspondingly, this embodiment sets up an automatic compensation mode, which is automatically activated when pump body aging is determined. The compensation mode includes:

[0095] Lower the vacuum pump's start-up pressure threshold;

[0096] Lower the vacuum pump shut-off pressure threshold;

[0097] The instrument system 10 sends a vacuum pump maintenance reminder to the user.

[0098] Lowering the vacuum pump's start-up pressure threshold allows it to start earlier, establishing the necessary vacuum environment for braking in advance and preventing the pump from failing to start in time due to aging. Lowering the vacuum pump's stop-down pressure threshold allows it to stop earlier, preventing prolonged operation, overheating, or overload caused by aging and slowing down. The overall goal is to maintain a usable and stable vacuum range even after the vacuum pump's efficiency declines due to aging, ensuring the braking assist does not fail. This embodiment also includes sending vacuum pump maintenance reminders to the user via the instrument system 10. This is because lowering the vacuum pump's start-up and stop-down pressure thresholds only provides temporary safety and cannot repair the aging of the vacuum pump. It is crucial to promptly remind the user / maintenance personnel that the vacuum pump has aged and experienced performance degradation, requiring inspection or replacement to prevent long-term operation with defects that could lead to safety hazards.

[0099] The technical effects of vacuum pump performance degradation modeling and compensation mechanisms are as follows:

[0100] (1) Improved braking system safety: By monitoring the performance degradation of the vacuum pump in real time, the brake pedal is prevented from becoming heavy and the braking distance is increased due to insufficient vacuum; at the same time, the compensation mode ensures sufficient vacuum assistance and ensures that the vehicle's braking performance does not drop suddenly during the pump aging stage.

[0101] (2) Avoid misjudgment and improve control robustness: By taking the average of multiple samples, instantaneous interference is filtered out, and pump aging will not be misjudged due to fluctuations in a single operating condition;

[0102] (3) Early warning of faults and reduction of safety accidents: The instrument actively prompts for maintenance, allowing the driver to deal with the problem before the vacuum booster completely fails, changing the post-fault repair to the pre-performance warning, which meets the safety design requirements of new energy vehicles.

[0103] Pure electric vehicles do not have an engine-driven vacuum pump; instead, they rely on an electronic vacuum pump to provide braking assistance. However, during regenerative braking (using the motor to generate electricity for deceleration), sudden changes in vehicle operating conditions (such as vehicle speed and motor torque) cause the logic of when the vacuum pump operates and stops to be completely different from that of traditional fuel vehicles (where the engine continuously drives the vacuum pump). This can lead to the following problems: When a pure electric vehicle releases the accelerator or lightly applies the brakes, the motor will first engage regenerative braking, and the vehicle will begin to decelerate. However, before the driver has fully applied the brakes, the traditional vacuum pump has not yet started. If the driver suddenly applies the brakes more heavily at this time, the vacuum in the brake lines will be insufficient, resulting in insufficient braking assistance, a stiffer brake, and consequently, a longer braking distance, posing a safety hazard. After the motor braking request ends, the driver often still has the brake pedal pressed. If the vacuum pump immediately shuts off, the vacuum level will drop rapidly, causing a sudden weakening of braking assistance in the latter half of the braking process. Therefore, the control method of this embodiment further includes: VCU1, in conjunction with the motor system 9, utilizes the vehicle deceleration characteristics during motor regenerative braking to predict the braking vacuum demand in advance. The specific operation is as follows.

[0104] When VCU1 receives a motor braking request from the motor system 9 and detects through the brake pedal depth sensor 2 that the current braking intensity is greater than a preset first braking intensity threshold (set to 20% in this embodiment, but can be flexibly set according to actual conditions in specific implementation): In the vacuum pump off state, by lowering the vacuum pump start-up pressure threshold, the vacuum pump is started earlier, allowing it to start and replenish gas earlier, avoiding emergency startup only when the vacuum level drops very low. The motor braking request indicates that the motor has intervened to decelerate. The condition setting of the current braking intensity being greater than the preset first braking intensity threshold is intended to filter out light braking (such as lightly applying the brakes while following the vehicle), providing additional protection only for medium to high intensity braking needs, and avoiding frequent start-stop of the vacuum pump that wastes energy.

[0105] If VCU1 detects through the motor system 9 that the brake pedal depth sensor 2 detects a current braking intensity greater than 0 after the motor braking request ends, then after the pipeline pressure is less than or equal to the vacuum pump shut-off pressure threshold, the vacuum pump will be shut off after a preset time delay (set to 5 seconds in this embodiment, but can be flexibly set according to actual conditions) before being shut off. After the motor braking ends, the driver may still be pressing the brake (braking intensity greater than 0). If the vacuum pump stops immediately at this time, the residual vacuum will be rapidly lost due to braking consumption, causing the pedal to suddenly become heavy or the braking force to be unstable. Therefore, this embodiment of the invention maintains a 5-second buffer time by delaying the shutdown of the vacuum pump, allowing the vacuum pump to continue to provide support and ensuring the consistency of assistance throughout the braking process.

[0106] This invention, through its embodiment, anticipates vacuum demand via motor braking signals, fully utilizing the pre-deceleration characteristics of regenerative braking to achieve pre-judgment of braking vacuum requirements. This addresses the issue of traditional fuel vehicle vacuum logic being incompatible with the braking modes of new energy vehicles. Simultaneously, it enables the vacuum pump to start early and shut down late. By lowering the vacuum pump's start-up pressure threshold, a vacuum is established earlier, resulting in more sufficient and timely brake assist. This avoids stiff braking and slow braking response due to insufficient vacuum. Furthermore, the delayed vacuum pump shutdown ensures consistent brake assist throughout the braking process. Ultimately, without increasing hardware costs, it guarantees sufficient brake assist, smooth pedal feel, and enhanced braking safety, improving the driving experience.

[0107] To ensure the long-term safe operation of the vacuum pump, the control method of this embodiment further includes: introducing an early warning mechanism for vacuum pump failures, including:

[0108] The health index (HI) of a vacuum pump is calculated using the following formula:

[0109] ;

[0110] in, This indicates the current average evacuation time of the vacuum pump. This indicates the average vacuum pumping time at the time of manufacture. This indicates the rated number of start-stop cycles for the vacuum pump. This indicates the cumulative number of times the vacuum pump has actually started and stopped; This indicates the natural pressure relief rate of the vacuum pump per unit time. , , This represents the preset weighting coefficients, and , , The sum is 1.

[0111] This formula uses three core characteristics that best reflect the aging / failure trend of vacuum pumps, weighted and fused into a comprehensive health index to achieve early fault warning. The three characteristics correspond to three typical failure modes of vacuum pumps:

[0112] In response to the decline in the pumping capacity of a vacuum pump, the core function of a vacuum pump is to quickly reach the target vacuum level. However, as vacuum pumps age or malfunction, pumping becomes slower, and the time to reach the target vacuum increases. Therefore, this embodiment uses the current average evacuation time of the vacuum pump. Average vacuum pumping time compared to factory settings By making a ratio, the performance degradation of different pump models can be standardized, and it is not affected by the differences in the specifications of the pumps themselves.

[0113] Corresponding to the mechanical fatigue loss of vacuum pumps, which belong to reciprocating / rotary machinery, frequent start-stop cycles are the main source of fatigue. The number of start-stop cycles directly determines the mechanical fatigue life and is a typical life-related indicator. This embodiment uses the rated number of start-stop cycles of the vacuum pump. Cumulative number of actual start-stop cycles of the vacuum pump The ratio can directly reflect the proportion of remaining service life consumed, and provide early warning of progressive failures such as vacuum pump bearing failure, seal fatigue, and motor aging.

[0114] In response to poor sealing / leakage of vacuum pumps and vacuum pump failure, leakage is the most common and difficult-to-detect early fault. It will cause a decrease in the pressure holding capacity of the vacuum pump, but it may not be obvious during pumping. The natural pressure relief rate is a direct measure of pressure holding performance and can capture micro-leakage that cannot be reflected by the pumping time, so as to accurately identify faults such as sealing deterioration, micro-leakage, and valve failure.

[0115] Finally, a comprehensive health index is calculated by weighting and fusing these three features, enabling early fault warning. The weighting coefficients for each feature can be flexibly set by the user according to actual needs, for example: , , This represents the preset weighting coefficients, and , , The sum is 1.

[0116] The corresponding evacuation time is the most critical functional indicator, and the most direct cause of failure is usually the greatest weight. The corresponding number of start-stop cycles reflects the mechanical lifespan; the trend is stable but changes slowly, and the weight is moderate. Corresponding to the natural pressure relief rate, it reflects the seal leakage and is sensitive to early failures, but is easily affected by the environment, so its weight is moderate or slightly low.

[0117] Finally, the vacuum pump health status is classified according to the calculated vacuum pump health index HI and corresponding intervention measures are taken. For example, a vacuum pump health status classification and corresponding intervention measures provided in this embodiment of the invention are shown in Table 1.

[0118] HI range state measure >0.8 normal No intervention required 0.6~0.8 Mild degradation Activate the compensation mechanism to remind you to perform maintenance. <0.6 Severe deterioration An alarm was triggered and conservative control mode was entered.

[0119] Table 1

[0120] The vacuum pump control system and method of this invention effectively address the shortcomings of existing technologies, achieving significant technical benefits. By adding temperature and humidity sensors and incorporating a three-dimensional correction factor based on atmospheric pressure, it achieves dynamic correction of vacuum control parameters under different environments, ensuring stable and reliable braking assistance in complex conditions. A performance degradation model is constructed, averaging multiple pumping times to determine aging and automatically compensating, avoiding misjudgments and providing early warnings, thus improving braking safety. The vacuum pump start-up and shutdown timing is optimized by integrating motor braking signals, enabling earlier start-up and delayed shutdown, resolving braking compatibility issues for new energy vehicles, reducing ineffective power consumption, and ensuring consistent braking assistance. Multi-dimensional health indices are introduced to achieve early fault warnings, combined with remote diagnostics and data storage, enabling pre-fault warnings, remote maintenance, and algorithm upgrades. Overall, without significantly increasing hardware costs, it improves the adaptability, reliability, safety, and energy efficiency of the vacuum pump system, optimizes user experience, and adapts to the needs of pure electric vehicles.

[0121] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A vacuum pump control system for a pure electric vehicle, characterized in that: The system includes a VCU (1), a brake pedal depth sensor (2), a pipeline pressure sensor (3), an atmospheric pressure sensor (4), a temperature sensor (5), a humidity sensor (6), a vacuum pump relay (7), a vacuum pump (8), a motor system (9), and an instrument system (10). The brake pedal depth sensor (2), pipeline pressure sensor (3), atmospheric pressure sensor (4), temperature sensor (5), and humidity sensor (6) are respectively connected to the VCU (1). The VCU (1) is connected to the vacuum pump (8) through the vacuum pump relay (7). The VCU (1) is connected to the motor system (9) and the instrument system (10) through a communication bus.

2. The vacuum pump control system for a pure electric vehicle according to claim 1, characterized in that: The system also includes a data storage unit (11) connected to the VCU (1).

3. The vacuum pump control system for a pure electric vehicle according to claim 1, characterized in that: The system also includes a remote diagnostic interface (12), which is connected to the VCU (1).

4. The vacuum pump control system for a pure electric vehicle according to claim 1, characterized in that: The system is powered by a 12V battery.

5. A vacuum pump control system for a pure electric vehicle according to claim 1, characterized in that: The VCU (1) is connected to the motor system (9) and the instrument system (10) via the CAN bus.

6. A vacuum pump control method for a pure electric vehicle, using a vacuum pump control system for a pure electric vehicle according to any one of claims 1-5, characterized in that: The control method includes: Step S1: VCU1 obtains the user-preset vacuum pump start-up pressure threshold and stop-down pressure threshold, wherein the start-up pressure threshold is greater than the stop-down pressure threshold; Step S2: The atmospheric pressure, ambient temperature and humidity of the vehicle's current environment are collected in real time by the atmospheric pressure sensor 4, temperature sensor 5 and humidity sensor 6 and sent to the VCU1. Step S3: Based on the atmospheric pressure, ambient temperature and humidity, VCU1 introduces a three-dimensional correction factor to dynamically correct the vacuum pump's opening pressure threshold and closing pressure threshold. Step S4: The vehicle brake line pressure is acquired in real time through the line pressure sensor 3 and sent to the VCU1; Step S5: VCU1 compares the real-time collected vehicle brake line pressure with the dynamically corrected vacuum pump opening pressure threshold and closing pressure threshold to determine whether to open or close the vacuum pump. When the vacuum pump is in the off state, it will be turned on when the real-time collected vehicle brake line pressure is greater than or equal to the dynamically corrected opening pressure threshold; when the vacuum pump is in the on state, it will be turned off when the real-time collected vehicle brake line pressure is less than or equal to the dynamically corrected closing pressure threshold.

7. The vacuum pump control method for a pure electric vehicle according to claim 6, characterized in that: Based on the atmospheric pressure, ambient temperature, and humidity, a three-dimensional correction factor is introduced to dynamically correct the vacuum pump's start-up and stop-down pressure thresholds, including: The three-dimensional correction factor F is expressed as follows: F = f(P, T, H); Wherein, P represents atmospheric pressure; T represents ambient temperature; H represents ambient humidity; and f represents the mapping relationship between P, T, H and the three-dimensional correction factor F, which is stored in the form of a data mapping table. VCU(1) obtains the corresponding three-dimensional correction factor F from the data mapping table based on the real-time collected atmospheric pressure P, ambient temperature T, and ambient humidity H, using a lookup table method combined with an interpolation algorithm. The correction factor is then applied to the vacuum pump's start-up pressure threshold and stop-down pressure threshold, as expressed by the following formula: P start-new =P start *F;P stop-new =P stop *F; Among them, P start and P stop These represent the vacuum pump start-up pressure threshold and stop-down pressure threshold before correction, respectively; P start-new and P stop-new These represent the corrected vacuum pump start-up pressure threshold and shut-off pressure threshold, respectively.

8. A vacuum pump control method for a pure electric vehicle according to claim 6, characterized in that: The control method further includes: introducing a vacuum pump performance degradation modeling and compensation mechanism, that is, the VCU (1) periodically performs the following operations: • Calculate the time t required for the vacuum pump to reach the preset pressure from startup in n consecutive cycles; • Calculate the average value of bar{t} of the time t required for the vacuum pump to reach the preset pressure from start-up for n consecutive cycles; • If bar{t} > t0, where t0 represents a preset time threshold, then the pump body is determined to be aging, and the compensation mode is automatically activated, including: • Reduce the vacuum pump's start-up pressure threshold; • Lower the vacuum pump shutdown pressure threshold; The system (10) sends a vacuum pump maintenance reminder to the user.

9. A vacuum pump control method for a pure electric vehicle according to claim 6, characterized in that: The control method further includes: the VCU (1) in conjunction with the motor system (9) uses the characteristic of vehicle deceleration during motor regenerative braking to predict braking vacuum demand in advance. When VCU (1) receives a motor braking request sent by the motor system (9) and detects through the brake pedal depth sensor (2) that the current braking intensity is greater than the preset first braking intensity threshold: in the vacuum pump off state, the vacuum pump is started in advance by reducing the vacuum pump start pressure threshold; If the VCU (1) detects through the motor system (9) that the brake pedal depth sensor (2) detects that the current braking intensity is greater than 0 after the motor braking request ends, then the vacuum pump will be turned off after a preset time when the pipeline pressure is less than or equal to the vacuum pump shut-off pressure threshold.

10. A vacuum pump control method for a pure electric vehicle according to claim 6, characterized in that: The control method further includes: introducing an early warning mechanism for vacuum pump failures, including: The health index (HI) of a vacuum pump is calculated using the following formula: ； in, This indicates the current average evacuation time of the vacuum pump. This indicates the average vacuum pumping time at the time of manufacture. This indicates the rated number of start-stop cycles for the vacuum pump. This indicates the cumulative number of times the vacuum pump has actually started and stopped; This indicates the natural pressure relief rate of the vacuum pump per unit time. , , This represents the preset weighting coefficients, and , , The sum is 1; Based on the calculated Vacuum Pump Health Index (HI), the health status of the vacuum pump is classified and corresponding intervention measures are taken.

Images