Vacuum boosting system of pure electric vehicle and fault judgment and control method of electronic vacuum pump

Abstract

The invention discloses a vacuum boosting system of a pure electric vehicle. The vacuum boosting system is provided with a vacuum tank and a pressure sensor, the vacuum tank is respectively connected with the vacuum booster and the electronic vacuum pump through pipelines; the pressure sensor is arranged on a pipeline for connecting the vacuum tank and the electronic vacuum pump; and the controller is respectively connected with the electronic vacuum pump and the pressure sensor through signal circuits. The invention further discloses a fault judgment and control method for the electronic vacuum pump of the vacuum boosting system. By the adoption of the technical scheme, the air leakage diagnosis strategy for the vehicle and the control strategy for the electronic vacuum pump after air leakage occur are improved, and it is guaranteed that under the condition that air leakage occurs in the electronic vacuum pump, the enough vacuum degree is achieved to guarantee driving safety; the braking requirement of a driver is met to the maximum extent, and the braking safety and the driving comfort of the driver are greatly improved; and meanwhile, the service life of the electronic vacuum pump is effectively prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of pure electric vehicle braking systems. More specifically, the present invention relates to a pure electric vehicle vacuum booster system. The present invention also relates to an electronic vacuum pump fault judgment and control method of the vacuum booster system. Background Art

[0002] With the popularization of new energy vehicles, pure electric vehicles lack engines to provide vacuum sources for the brake system compared to traditional fuel vehicles, so the brake system of pure electric vehicles generally uses electronic vacuum pumps to provide vacuum sources for the brake system. The working frequency of the electronic vacuum pump is very high, especially when there is a slight or even serious leak in the entire brake system, it needs to work at a high load, which can easily cause the electronic vacuum pump to burn and damage, especially during driving. Safety accidents are prone to occur.

[0003] Defects of the prior art:

[0004] In the case of air leakage in the pipeline system, what kind of logic should be used to control the working time of the electronic vacuum pump, so as to extend the working life of the electronic vacuum pump and ensure that the brake system has enough vacuum to ensure that the vehicle can brake effectively. However, the existing technology has not been able to solve this problem well. In the case of air leakage in the brake system, the electronic vacuum pump will start and stop frequently, and even burn out due to long-term operation.

[0005] The following search results were obtained by searching the existing public technical literature using keywords such as "vacuum; booster; pump; air leakage; fault; judgment":

[0006] 1. Chinese patent document: "A fault diagnosis method for a vacuum-assisted braking system of a pure electric vehicle", patent (application) number: 201410369105.4; the technical solution recorded is:

[0007] "The vacuum assisted braking system of pure electric vehicles includes a vehicle control unit (HCU), an electric vacuum pump, a vacuum pressure sensor, a meter, a brake pedal, a relay and a power supply. The HCU and the meter communicate with each other via a CAN line, and other parts are connected to the HCU via hard wires."

[0008] "The fault diagnosis method is as follows: after the electric vehicle is powered on, the vehicle controller collects the power supply information of the vacuum pump in real time to determine whether the power is disconnected; the vehicle controller collects the change value of the vacuum pressure in real time, and determines whether the vacuum boost system is leaking, the vacuum pumping performance is reduced, and whether it is in a continuous working state according to the working state of the vacuum pump (working, stopped) and the driver's braking operation";

[0009] The technical effects recorded are:

[0010] "The fault diagnosis method is relatively comprehensive, systematic and clear. It can accurately locate the cause of the vacuum failure, warn the driver in time, and improve the driving safety of the vehicle."

[0011] 2. Chinese patent document: "Vacuum boost system detection method and system, electric vehicle and fault detection method", patent (application) number: 201310264166.X; the technical solution recorded is:

[0012] “The vacuum boost system detection method comprises the following steps: first, determining whether the pressure sensor is faulty, and after ensuring that the pressure sensor is faulty, further diagnosing vacuum pump failure or vacuum boost system leakage according to the accurate measurement signal output by the pressure sensor”;

[0013] The technical effects recorded are:

[0014] "Accurate and comprehensive testing of the vacuum power assist system can quickly determine the location of the failure once the vacuum power assist system fails, effectively improving the reliability of the vacuum power assist system and ensuring safe driving of electric vehicles."

[0015] However, the technical solutions recorded in the above-mentioned technical documents and the related technical solutions currently in public application have not actually been able to effectively solve the problems and defects existing in the prior art that "in the event of air leakage in the brake system, the electronic vacuum pump will start and stop frequently, or even burn out due to long-term operation." Summary of the invention

[0016] The present invention provides a pure electric vehicle vacuum boost system, which aims to improve the strategy for diagnosing air leakage in the vacuum boost system and the control strategy for an electronic vacuum pump after air leakage occurs.

[0017] In order to achieve the above object, the technical solution adopted by the present invention is:

[0018] The vacuum boosting system of a pure electric vehicle of the present invention comprises wheels, a controller, an electronic vacuum pump and a vacuum booster; the vacuum booster brakes the wheels; the vacuum boosting system is provided with a vacuum tank and a pressure sensor; the vacuum tank is respectively connected with the vacuum booster and the electronic vacuum pump through pipelines; the pressure sensor is arranged on the pipeline connecting the vacuum tank and the electronic vacuum pump; the controller is respectively connected with the electronic vacuum pump and the pressure sensor through a signal circuit.

[0019] The controller is connected to the instrument through a circuit. The controller is connected to the TBOX through a circuit.

[0020] In order to achieve the same invention purpose as the above technical solution, the present invention also provides the above-mentioned electronic vacuum pump fault judgment and control method of the pure electric vehicle vacuum booster system, and its technical solution is:

[0021] The air pressure failure of the electronic vacuum pump includes air leakage failure and air extraction failure, wherein: the air leakage failure is divided into two levels, namely, a slight air leakage failure and a severe air leakage failure; the air extraction failure is divided into two levels, namely, a slight air extraction failure and a severe air extraction failure;

[0022] The diagnostic process of the air leakage fault is:

[0023] The electronic vacuum pump is not enabled and the brake pedal is not pressed. When both conditions are met at the same time, the diagnostic window is opened after time t0=0.5s, and the latched air pressure value is updated once after t1=1s; after time t2=2s, the controller detects the real-time pressure value in the vacuum tank again through the pressure sensor.

[0024] The judgment criteria for the air leakage fault are:

[0025] 1) When the air pressure difference is greater than 5kPa, it is judged as a serious air leakage fault;

[0026] 2) When the air pressure difference is greater than 3kPa and less than 5kPa, it is judged as a slight air leakage fault;

[0027] 3) The brake pedal is not depressed, the electronic vacuum pump is enabled for 15 consecutive times with the same enabling time, and the threshold for judging slight air leakage is not reached. In this case, it is judged as a slight air leakage fault.

[0028] The air pressure difference is: real-time air pressure minus locked air pressure value.

[0029] The method for detecting and judging the air extraction fault is:

[0030] The electronic vacuum pump is enabled and the brake pedal is not depressed. The current air pressure value is latched after t0=0.5s. After the calibration time t2=3s, the controller detects the current pressure value in the vacuum tank again through the pressure sensor. The normal air pumping capacity threshold is determined by looking up the table based on the first latched air pressure value, and the system air pumping degree is determined based on the difference between the two air pressures.

[0031] The table lookup mentioned above refers to the table of normal pumping capacity threshold value, as shown in the following table:

[0032] Latch value(kPa) 90 80 70 60 50 40 30 Normal pumping capacity threshold (kPa) 19 16 13 10 7 5 3

[0033] In the case that no fault is detected by the electronic vacuum pump:

[0034] 1) Mild pumping failure: the difference is between the coefficient 0.6×normal pumping capacity threshold and the coefficient 1×normal pumping capacity threshold;

[0035] 2) Severe pumping failure: The difference is less than the coefficient 0.6×normal pumping capacity threshold.

[0036] In case of leakage in the electronic vacuum pump:

[0037] 1) Mild pumping failure: the difference is between the coefficient 0.3×normal pumping capacity threshold and the coefficient 1×normal pumping capacity threshold;

[0038] 2) Severe pumping failure: The difference is less than coefficient 0.3 × coefficient 0.6 × normal pumping capacity threshold.

[0039] The enabling control strategy of the control method described is:

[0040] 1) Enable in case of a minor fault: If there is a minor fault and the current air pressure is greater than the enable air pressure value, the system will enable the device for 20 seconds. If the condition is met again: the pressure value is greater than the enable air pressure value, the device will enable the device for another 20 seconds, leaving a time protection window: enable the device for 20 seconds and stop for 5 seconds.

[0041] 2) Serious fault enable: In case of serious fault, it will be enabled for 10 seconds, stop for 5 seconds, and repeat the operation.

[0042] The present invention adopts the above technical scheme, and on the basis of adopting a low-cost electronic vacuum pump, improves the vehicle leakage diagnosis strategy and the control strategy of the electronic vacuum pump after the leakage occurs, so as to ensure that there is sufficient vacuum degree to ensure driving safety in the event of an electronic vacuum pump leakage; to meet the driver's braking needs to the greatest extent, greatly improve the braking safety and the driver's driving comfort; at the same time, effectively extend the service life of the electronic vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The contents shown in the attached drawings and the symbols in the drawings are briefly described as follows:

[0044] Figure 1 It is a schematic structural diagram of the vacuum power assist system of the present invention.

[0045] Figure 2 is a gas leakage fault diagnosis strategy diagram of the present invention;

[0046] Figure 3 This is a diagram of the exhaust fault diagnosis strategy of the present invention.

[0047] The markings in the figure are:

[0048] 1. Electronic vacuum pump, 2. Controller, 3. Instrument, 4. TBOX, 5. Pressure sensor, 6. Vacuum tank, 7. Vacuum booster, 8. Wheel. DETAILED DESCRIPTION

[0049] The specific implementation modes of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0050] like Figure 1 The structure shown is a pure electric vehicle vacuum boost system provided by the present invention, wherein the pure electric vehicle comprises a wheel 8, a controller 2, an electronic vacuum pump 1 and a vacuum booster 7; the vacuum booster 7 brakes the wheel 8. The present invention adopts a low-cost structural solution and simultaneously performs electronic vacuum pump fault diagnosis and control through corresponding logic.

[0051] In order to solve the problems existing in the prior art and overcome its defects, realize the invention purpose of improving the strategy of leak diagnosis for the vacuum booster system, and the control strategy of the electronic vacuum pump after the leak occurs, the technical solution adopted by the present invention is:

[0052] like Figure 1 As shown, the vacuum booster system of a pure electric vehicle of the present invention is provided with a vacuum tank 6 and a pressure sensor 5; the vacuum tank 6 is connected to a vacuum booster 7 and an electronic vacuum pump 1 respectively through pipelines; the pressure sensor 5 is arranged on the pipeline connecting the vacuum tank 6 and the electronic vacuum pump 1; the controller 2 is connected to the electronic vacuum pump 1 and the pressure sensor 5 respectively through signal circuits.

[0053] The beneficial effects of the present invention are as follows: based on the current solution of using a low-cost electronic vacuum pump 1, the vehicle of the present invention implements a leakage diagnosis strategy and a control strategy for the electronic vacuum pump 1 after a leakage occurs, which ensures that there is sufficient vacuum to ensure driving safety when the electronic vacuum pump 1 leaks, while effectively extending the service life of the electronic vacuum pump 1.

[0054] The controller 2 is connected to the instrument 3 through a circuit. The controller 2 is connected to the TBOX4 through a circuit.

[0055] The nature and severity of the fault are displayed by instrument 3, which helps the operator and driver to take corresponding technical measures.

[0056] TBOX in cars refers to "Telematics BOX", which is a telematics control unit. TBOX is an important part of the Internet of Vehicles system and its core component. It is mainly responsible for the information exchange between the vehicle and the outside world, supports remote control, data collection, navigation, emergency rescue and other functions, and is widely used in the fields of Internet of Vehicles, fleet management, insurance and shared travel.

[0057] Here are the main features of TBOX:

[0058] 1. Remote communication: communicate with cloud servers through cellular networks (such as 4G, 5G) to achieve remote control, data upload and download;

[0059] 2. Data collection: collect vehicle status information, such as location, speed, fuel consumption, fault codes, etc., and upload it to the cloud;

[0060] 3. Remote control: remotely control the vehicle through mobile phone APP or cloud platform, such as starting, locking, air conditioning control, etc.;

[0061] 4. Navigation and positioning: provide real-time navigation and vehicle positioning services;

[0062] 5. Emergency rescue: Automatically send help signals and location information in the event of an accident or emergency;

[0063] 6. OTA upgrade: supports software upgrades via wireless networks to improve vehicle performance and functions.

[0064] The main components of TBOX:

[0065] 1. Communication module: support cellular network, Wi-Fi, Bluetooth, etc.;

[0066] 2. GPS module: used for positioning and navigation;

[0067] 3. Processor: processes data and executes instructions;

[0068] 4. Memory: stores vehicle data and software;

[0069] 5. Interface: connected with vehicle CAN bus and other systems.

[0070] Application scenarios of TBOX:

[0071] 1. Internet of Vehicles: Connecting vehicles with the cloud, other vehicles and infrastructure;

[0072] 2. Fleet management: monitor and manage fleet status;

[0073] 3. Insurance: Provide driving behavior data for insurance pricing;

[0074] 4. Shared travel: supports remote control and vehicle status monitoring.

[0075] In order to achieve the same invention purpose as the above technical solution, the present invention also provides the above-mentioned electronic vacuum pump fault judgment and control method of the pure electric vehicle vacuum booster system, and its technical solution is:

[0076] Leakage judgment:

[0077] The air pressure failure of the electronic vacuum pump 1 includes air leakage failure and air extraction failure, wherein: the air leakage failure is divided into two levels, namely, a mild air leakage failure and a severe air leakage failure:

[0078] like Figure 2 As shown, the diagnostic process of the air leakage fault is:

[0079] When the electronic vacuum pump 1 is not enabled and the brake pedal is not pressed, and both conditions are met at the same time, the diagnostic window is opened after time t0=0.5s, and the latched air pressure value is updated once after t1=1s; after time t2=2s, the controller 2 detects the real-time pressure value in the vacuum tank 6 again through the pressure sensor 5.

[0080] The judgment criteria for the air leakage fault are:

[0081] 1. When the air pressure difference is greater than 5kPa, it is judged as a serious air leakage fault;

[0082] 2. When the air pressure difference is greater than 3kPa and less than 5kPa, it is judged as a slight air leakage fault;

[0083] 3. The brake pedal is not depressed, the electronic vacuum pump 1 is enabled 15 times in succession with the same enabling time, and the threshold for judging slight air leakage is not reached. In this case, it is judged as a slight air leakage fault.

[0084] The air pressure difference is: real-time air pressure minus locked air pressure value.

[0085] The pumping failure is divided into two levels, namely, a mild pumping failure and a severe pumping failure.

[0086] like Figure 3 As shown, the method for detecting and judging the air extraction fault is:

[0087] When the electronic vacuum pump 1 is enabled and the brake pedal is not depressed, the current air pressure value is latched after t0=0.5s. After the calibration time t2=3s, the controller 2 detects the current pressure value in the vacuum tank 6 again through the pressure sensor 5. The normal air pumping capacity threshold is determined by looking up the table based on the first latched air pressure value (see Table 1), and the system air pumping degree is determined based on the difference between the two air pressures.

[0088] The table lookup mentioned above refers to a table of normal pumping capacity threshold values, as shown in Table 1 below:

[0089] Table 1. Normal pumping capacity threshold

[0090] Latch value(kPa) 90 80 70 60 50 40 30 Normal pumping capacity threshold (kPa) 19 16 13 10 7 5 3

[0091] When no fault is detected in the electronic vacuum pump 1:

[0092] 1. Mild pumping failure: the difference is between the coefficient 0.6 × normal pumping capacity threshold and the coefficient 1 × normal pumping capacity threshold;

[0093] 2. Severe pumping failure: The difference is less than the coefficient 0.6 × normal pumping capacity threshold.

[0094] When the electronic vacuum pump 1 is leaking:

[0095] 1. Mild pumping failure: the difference is between the coefficient 0.3×normal pumping capacity threshold and the coefficient 1×normal pumping capacity threshold;

[0096] 2. Severe pumping failure: The difference is less than coefficient 0.3 × coefficient 0.6 × normal pumping capacity threshold.

[0097] The enabling control strategy of the control method described is:

[0098] 1. Enable in case of a minor fault: If there is a minor fault and the current air pressure is greater than the enable air pressure value, the system will enable the device for 20 seconds. If the condition is met again: the pressure value is greater than the enable air pressure value, the device will enable the device for another 20 seconds, leaving a time protection window: enable the device for 20 seconds and stop for 5 seconds.

[0099] 2. Serious fault enable: In case of serious fault, enable for 10s, stop for 5s, and repeat the operation.

[0100] The key concept of the present invention is to improve the diagnostic strategy of the electronic vacuum pump 1. When a leakage fault occurs in the vacuum booster system, a corresponding fault control mode will be implemented to meet the driver's braking needs to the greatest extent, greatly improving braking safety and driving comfort of the driver, while effectively extending the working life of the electronic vacuum pump 1.

[0101] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A vacuum booster system for a pure electric vehicle, the pure electric vehicle comprising a wheel (8), a controller (2), an electronic vacuum pump (1) and a vacuum booster (7); the vacuum booster (7) brakes the wheel (8); the characteristics are: The vacuum boosting system is provided with a vacuum tank (6) and a pressure sensor (5); the vacuum tank (6) is connected to a vacuum booster (7) and an electronic vacuum pump (1) through pipelines; the pressure sensor (5) is arranged on the pipeline connecting the vacuum tank (6) and the electronic vacuum pump (1); the controller (2) is connected to the electronic vacuum pump (1) and the pressure sensor (5) through signal circuits.

2. The vacuum boost system for a pure electric vehicle according to claim 1, characterized in that: The controller (2) is connected to the instrument (3) via an electric circuit.

3. The vacuum boost system for a pure electric vehicle according to claim 1, characterized in that: The controller (2) is connected to the TBOX (4) via a circuit.

4. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to any one of claims 1 to 3, characterized in that: The air pressure failure of the electronic vacuum pump (1) includes a leakage failure and an exhaust failure, wherein: the leakage failure is divided into two levels, namely a mild leakage failure and a severe leakage failure; the exhaust failure is divided into two levels, namely a mild exhaust failure and a severe exhaust failure; The diagnostic process of the air leakage fault is: When the electronic vacuum pump (1) is not enabled and the brake pedal is not depressed, and both conditions are met at the same time, the diagnostic window is opened after time t0 = 0.5s, and the latched air pressure value is updated once after time t1 = 1s; after time t2 = 2s, the controller (2) detects the real-time pressure value in the vacuum tank (6) again through the pressure sensor (5).

5. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 4, characterized in that: The judgment criteria for the air leakage fault are: 1) When the air pressure difference is greater than 5kPa, it is judged as a serious air leakage fault; 2) When the air pressure difference is greater than 3kPa and less than 5kPa, it is judged as a slight air leakage fault; 3) The brake pedal is not depressed, the electronic vacuum pump (1) is enabled 15 times in succession with the same enabling time, but fails to reach the threshold for judging slight air leakage. In this case, it is judged as slight air leakage fault.

6. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 5, characterized in that: The air pressure difference is: real-time air pressure minus locked air pressure value.

7. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 4, characterized in that: The method for detecting and judging the air extraction fault is: The electronic vacuum pump (1) is enabled and the brake pedal is not depressed. After t0=0.5s, the current air pressure value is latched. After a calibrated time t2=3s, the controller (2) detects the current pressure value in the vacuum tank (6) again through the pressure sensor (5). The normal air extraction capacity threshold is determined by looking up the table based on the first latched air pressure value, and the system air extraction degree is determined based on the difference between the two air pressures.

8. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 7, characterized in that: The table lookup mentioned above refers to the normal pumping capacity threshold table, as shown in the following table:

9. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 7, characterized in that: In the case that no fault is detected in the electronic vacuum pump (1): 1) Mild pumping failure: the difference is between the coefficient 0.6×normal pumping capacity threshold and the coefficient 1×normal pumping capacity threshold; 2) Severe pumping failure: The difference is less than the coefficient 0.6×normal pumping capacity threshold. When the electronic vacuum pump (1) is leaking: 1) Mild pumping failure: the difference is between the coefficient 0.3×normal pumping capacity threshold and the coefficient 1×normal pumping capacity threshold; 2) Severe pumping failure: The difference is less than coefficient 0.3 × coefficient 0.6 × normal pumping capacity threshold.

10. The method for judging and controlling the fault of an electronic vacuum pump of a vacuum booster system of a pure electric vehicle according to claim 7, characterized in that: The enabling control strategy of the control method described is: 1) Enable in case of minor fault: If there is a minor fault and the current air pressure is greater than the enable air pressure value, it will be enabled for 20 seconds until the conditions are met again: The pressure value is greater than the enabling pressure value, and then it is enabled for 20 seconds, leaving a time protection window: enable for 20 seconds and stop for 5 seconds; 2) Serious fault enable: In case of serious fault, it will be enabled for 10 seconds, stop for 5 seconds, and repeat the operation.

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