CN113954809A - Diagnosis method and system of vehicle vacuum boosting system - Google Patents
Diagnosis method and system of vehicle vacuum boosting system Download PDFInfo
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- CN113954809A CN113954809A CN202111268870.3A CN202111268870A CN113954809A CN 113954809 A CN113954809 A CN 113954809A CN 202111268870 A CN202111268870 A CN 202111268870A CN 113954809 A CN113954809 A CN 113954809A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/18—Safety devices; Monitoring
- B60T17/22—Devices for monitoring or checking brake systems; Signal devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/24—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being gaseous
- B60T13/46—Vacuum systems
- B60T13/52—Vacuum systems indirect, i.e. vacuum booster units
Abstract
The invention discloses a diagnostic method and a diagnostic system of a vacuum boosting system for a vehicle, which comprises the steps of collecting pressure information of a vacuum air storage tank, outside air pressure information, brake pedal information, working state information of a vacuum pump and duration of completely loosening a brake pedal; calculating a first air pressure alarm threshold and a second air pressure alarm threshold corresponding to at least two different working conditions according to the information; under different working conditions, when the air pressure of the vacuum air storage tank is higher than or equal to the air pressure alarm threshold value under the corresponding working condition, the alarm prompts that the vacuum degree of the current vacuum boosting system is insufficient. By utilizing the method and the system, the diagnosis can be more timely, and the misdiagnosis can be effectively filtered, so that the driving experience is improved, and the safety of the vehicle is improved.
Description
Technical Field
The invention belongs to the technical field of electric control, and particularly relates to a diagnosis method and system of a vacuum boosting system for a vehicle.
Background
Vehicles are often equipped with vacuum assist systems to increase braking force to ensure braking efficiency. When trampling brake pedal, open and close through the pneumatic valve and control vacuum booster inner chamber respectively and seal and the exocoel is opened, form the atmospheric pressure behind exocoel and the atmosphere UNICOM like this and be higher than the inner chamber, slidable diaphragm is the division wall of inner chamber and exocoel, and under atmospheric pressure difference's effect, exocoel atmospheric pressure promotes the diaphragm, and diaphragm transmission thrust to checking cylinder promotes brake fluid pressure to obtain good braking effect. When the brake pedal is released, the air valve communicated with the atmosphere in the outer cavity of the vacuum booster is closed, the air valve communicated with the inner cavity and the outer cavity is opened, the residual atmosphere in the outer cavity enters the inner cavity, and the spring pushes the diaphragm to reset after the pressure difference of the inner cavity and the outer cavity is balanced. The vacuum pump maintains the vacuum degree of the vacuum system by pumping out air of the vacuum system.
Vacuum assisted brake systems require constant monitoring and diagnostics in relation to vehicle braking performance and safety, and thus there is a great deal of literature focusing on the diagnostic problems of vacuum assisted systems. It can be known from the basic working principle of the vacuum boosting system that the reduction of the vacuum degree of the vacuum air storage cavity can be caused by the fact that the external air enters the vacuum air storage cavity from the external cavity due to normal braking operation, and can also be caused by the fact that the external air enters the vacuum air storage cavity due to real leakage. Generally, in order to ensure the boosting braking effect of the boosting system, a vacuum degree threshold value is set, and when the vacuum degree threshold value is lower than the vacuum degree threshold value, a fault is judged. However, the vacuum degree of the vacuum system is easy to change frequently during work, and the system is easy to misjudge whether the vacuum degree is caused by operation or is actually leaked when the vacuum degree is lower.
The prior art is that the combination judgment is carried out according to the vacuum degree information and the brake switch frequency information, if the brake switch is frequent and the vacuum degree is lower than a first threshold value and the brake switch detects that a person frequently steps on the brake, the vacuum degree is diagnosed to possibly reduce due to manual operation, the reduction of brake operation is prompted, and therefore the fault false alarm of the brake system due to manual operation can be filtered to a certain extent.
One of the problems with the above diagnostic techniques is that the diagnosis is not timely enough. Because the vacuum degree is reduced in a short time due to brake stepping and brake releasing, the judgment time is too short, the false alarm is easy to form, and the delay is difficult to avoid by setting a period of continuous judgment time. The method of filtering the human operation by detecting the brake switch also has the problem that the operation frequency can be confirmed for diagnosis after the human operation is detected for many times, and has obvious delay.
The other problem of the diagnosis technology is that the change of the vacuum degree is not reasonably diagnosed and filtered, and the possibility of false alarm or false alarm exists. The brake stepping, brake releasing operation and the dynamic pressure change of the working state of the vacuum pump are in fact regular. According to the working principle of a vacuum booster, a brake pedal is stepped, a diaphragm moves, the total volume of a vacuum gas storage cavity is reduced, the air pressure and the volume are increased in inverse proportion, and the vacuum degree is reduced; when the brake pedal is released, the diaphragm returns, the air in the outer cavity volume enters the vacuum air storage cavity, the air pressure is increased, and the vacuum degree is reduced. After the vacuum pump is started, pumping air at a certain speed, and increasing the vacuum degree. Therefore, the vacuum degree is dynamic when a driver steps on and releases the brake pedal, the threshold value also needs to change along with the driving operation and the working state of the vacuum pump, otherwise, the vacuum degree reduction moment when the system is normal can be alarmed due to the fact that the threshold value is exceeded, or abnormal vacuum degree reduction cannot be identified.
In order to solve the problem of insufficient vacuum degree diagnosis of the conventional vacuum boosting system, the invention provides a diagnosis method, so that diagnosis is more timely, misdiagnosis can be effectively filtered, and the diagnosis robustness is improved, so that the driving experience is improved, and the vehicle safety is improved.
Disclosure of Invention
The invention provides a method and a system for diagnosing a vacuum boosting system for a vehicle, which realize one purpose of the invention and comprise the following steps:
s1, collecting pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank, and completely releasing the brake pedal;
the brake pedal information comprises a brake pedal state and a brake pedal stroke, the brake pedal state comprises a free state and a stepping state, the brake pedal stroke refers to the stroke percentage corresponding to the free state that the pedal is not stepped on being 0%, the stroke percentage corresponding to the maximum stroke when the brake pedal is stepped on is 100%, and the stroke of the brake pedal can be obtained by a sensor; the complete release of the brake pedal means that the brake pedal is completely released when the stroke percentage reaches 3% or less in the process of descending the stroke of the brake pedal from large to small.
S2, calculating a first air pressure alarm threshold and a second air pressure alarm threshold corresponding to at least two different working conditions according to the information;
the at least two different working conditions comprise a brake pedal state which is in a free state and a braking state.
Further, the working condition at least comprises that the brake pedal is in a free state, and the calculation of the first air pressure alarm threshold value of the brake pedal in the free state comprises the following steps: when the vacuum pump is not started, the first air pressure alarm threshold value is a first calibration value; when the vacuum pump works, the first air pressure alarm threshold value is a second calibration value.
The second calibration is linearly related to a time since a last complete release of the brake pedal, and the second calibration decreases as the time since the last complete release of the brake pedal increases.
Considering that the previous braking operation causes outside air to enter the vacuum air storage tank, the vacuum pump needs a certain time to pump the air to reach the target air pressure threshold value. Therefore, the closer to the moment of completely releasing the brake pedal the last time, the higher the air pressure threshold for diagnosing that the vacuum degree of the current vacuum boosting system is insufficient (the air pressure of the vacuum air storage system is high, the corresponding vacuum degree is low), the longer the time from the last completely releasing the brake pedal is, the lower the threshold is along with the lengthening of the time, and therefore when the vacuum pump works, the dynamic threshold is the second calibration value. For example, when the brake is frequently applied, the shorter the brake pedal is kept in the free state, the higher the corresponding diagnostic air pressure threshold value is; the set air pressure threshold value is gradually reduced along with the increase of the holding time of the brake pedal in the free state and the starting of the vacuum pump; when the holding time exceeds the set time length, theoretically considering that the air pressure in the vacuum air storage tank reaches a target value, the vacuum pump finishes air extraction and stops, therefore, when the vacuum pump works to reach the set time length after the pedal is loosened, the air pressure value of the vacuum air storage tank is higher than a first calibrated value; the first calibration value can be obtained by measuring the maximum pressure value that can be reached under normal conditions of the vacuum system and adding a certain margin.
Further, the working condition at least comprises that a brake pedal is in a stepping state, and the calculation of the second air pressure alarm threshold value of the brake pedal in the stepping state comprises the following steps:
s301, obtaining a volume change value of a space formed by an inner cavity of the vacuum booster and the vacuum air storage tank according to the stroke of the brake pedal;
when the brake pedal is stepped on, the volume formed by the inner cavity and the vacuum air storage tank is compressed due to the movement of the diaphragm, and the diaphragm is pushed by the push rod of the brake pedal, so that the change of the volume can be obtained by mapping the stroke of the brake pedal.
S302, calculating a pressure change value delta P _ v of a space formed by the vacuum booster inner cavity and the vacuum air storage tank according to an air pressure value of the vacuum tank, a volume change value of a space formed by the vacuum booster inner cavity and the vacuum air storage tank, an inner cavity volume of a vacuum booster diaphragm in a free state, and a volume of the vacuum air storage tank; the calculation method comprises the following steps:
wherein L isapThe volume of the inner cavity of the vacuum booster diaphragm in a free state; l isvcIs the volume of the vacuum air storage tank; the delta V is a volume change value of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank due to the movement of the diaphragm; pt1_0The obtained air pressure value of the vacuum tank was measured for the time when the brake pedal was last depressed and the stroke reached 3%.
S303, obtaining an air pressure reduction rate according to the air pressure value of the current vacuum air storage tank;
the vacuum pump reduces the air tank pressure by pumping air, but the pumping capacity is related to the current air tank pressure, so the air pressure reduction rate can be mapped by the current air tank pressure value.
S304, calculating the air pressure reduction change value delta P after the brake pedal is stepped on and the vacuum pump is started according to the air pressure reduction ratep；
S305, according to the air pressure value of the vacuum tank, the pressure change value delta P _ v and the air pressure reduction change value delta P of the space formed by the inner cavity of the vacuum booster and the vacuum air storage tankpA second air pressure warning threshold is calculated.
And S3, under different working conditions, when the air pressure of the vacuum air storage tank is higher than or equal to the air pressure alarm threshold value under the corresponding working condition, alarming to prompt that the vacuum degree of the current vacuum boosting system is insufficient.
The diagnostic system for a vacuum booster system for a vehicle, which achieves the second object of the present invention, includes:
an acquisition module: the system is used for acquiring pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank and the duration of completely loosening the brake pedal;
a calculation module: according to the information acquired by the acquisition module and the duration of releasing the brake pedal, calculating air pressure alarm thresholds under different working conditions;
a judging module: when the air pressure of the vacuum air storage cavity is higher than or equal to the air pressure alarm threshold under the corresponding working condition, the alarm module is started to give an alarm prompt;
an alarm module: the vacuum degree prompting device is used for prompting drivers and passengers to give an alarm to prompt that the vacuum degree of the current vacuum boosting system is insufficient.
Further, the calculation module includes:
a first barometric pressure threshold calculation module: the air pressure alarm threshold value is used for calculating the air pressure alarm threshold value when the brake pedal is in a free state and the vacuum pump is not started and/or is started;
and the second air pressure threshold value calculating module is used for calculating an air pressure alarm threshold value when the vacuum pump is not started and/or started under the stepping state of the brake pedal.
Further, the first air pressure threshold calculation module further comprises a first clock module for calculating a time period from a last complete release of the brake pedal.
Further, the second air pressure threshold calculation module includes:
a brake pedal stroke acquisition module: the system is used for acquiring the stroke of a brake pedal;
a volume change calculation module: the volume change value of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank is calculated according to the stroke of the brake pedal;
a pressure change calculation module; the pressure change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank is calculated according to the volume change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank, the inner cavity volume of the vacuum booster diaphragm in a free state, the volume of the vacuum air storage tank and the air pressure value of the vacuum tank;
the air pressure reduction rate calculation module: the air pressure reduction rate is calculated according to the current air pressure value of the vacuum air storage tank;
the air pressure drop change value calculation module: and calculating the air pressure reduction change value after the brake pedal is stepped down and the vacuum pump is started according to the air pressure reduction rate.
Further, the air pressure drop change value calculation module further comprises a second clock module: for acquiring a second clock module: and the method is used for acquiring the starting moment of the vacuum pump in the process of last stepping on the brake pedal.
By utilizing the method and the system, misdiagnosis can be effectively filtered, and the diagnosis robustness is improved, so that the driving experience is improved, and the vehicle safety is improved.
Drawings
FIG. 1 illustrates the structure and principles of a real power assist system according to the present invention;
the brake system comprises a brake pedal 1, a brake pedal stroke sensor 2, a vacuum booster 3, a brake pedal push rod 3-1, an external cavity air valve 3-2, an internal wall air valve 3-3, a diaphragm 3-4, a spring 3-5, a brake master cylinder push rod 3-6, a vacuum reservoir tank 4, a vacuum degree sensor 5, a vacuum pump 6, a hydraulic sensor 7 and a brake master cylinder 8;
fig. 2 is a schematic diagram of the diagnostic system according to the present invention.
Detailed Description
The following detailed description is provided for the purpose of explaining the claimed embodiments of the present invention so that those skilled in the art can understand the claims. The scope of the invention is not limited to the following specific implementation configurations. It is intended that the scope of the invention be determined by those skilled in the art from the following detailed description, which includes claims that are directed to this invention.
In addition, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not intended to indicate or imply relative importance.
First, the structure and principle of the vacuum boosting system will be described with reference to fig. 1. The brake pedal is contacted with a brake pedal push rod, and the brake pedal push rod translates to transmit the brake pedal thrust. The brake pedal travel sensor acquires pedal travel information. When the air valve is in a free state, the air valve of the inner cavity is opened, and the air valve of the outer cavity is closed. If the brake pedal is stepped on, the push rod of the brake pedal translates to push the inner cavity air valve to be closed, and the outer cavity air valve is opened. At the moment, the outer cavity is communicated with the external atmosphere, and the inner cavity is communicated with the vacuum air storage tank, so that the air pressure of the outer cavity is greater than that of the inner cavity, and under the action of the air pressure difference, the diaphragm moves to form resultant force with the push rod of the brake pedal to push the brake master cylinder, so that the brake hydraulic pressure is improved. The brake hydraulic pressure is transmitted to the brake through the brake fluid loop to form braking. When the pedal is released, the brake pedal push rod returns, the outer cavity air valve is closed, the inner cavity air valve is opened, and the inner cavity is communicated with the outer cavity again. At this time, the gas with higher pressure remained in the outer cavity enters the inner cavity through the inner cavity gas valve. Along with the pressure of the inner cavity and the pressure of the outer cavity are restored to be balanced, the spring of the vacuum booster pushes the diaphragm to reset. The vacuum pump is communicated with the vacuum pump through an air pipe, and the air pressure value of the vacuum air storage tank is maintained through opening and closing control. The air pressure information of the vacuum air storage tank and the hydraulic information of the brake master cylinder are obtained through different pressure sensors respectively.
Fig. 2 is a schematic diagram of the system framework, which includes an acquisition module: the system is used for acquiring pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank and the duration of completely loosening the brake pedal; a calculation module: according to the information acquired by the acquisition module and the duration of releasing the brake pedal, calculating air pressure alarm thresholds under different working conditions; a judging module: when the air pressure of the vacuum air storage cavity is higher than or equal to the air pressure alarm threshold under the corresponding working condition, the alarm module is started to give an alarm prompt; an alarm module: the vacuum degree prompting device is used for prompting drivers and passengers to give an alarm to prompt that the vacuum degree of the current vacuum boosting system is insufficient.
The acquisition module can be for installing the sensor on each relevant part of vehicle, including pressure sensor, atmospheric pressure collector, brake pedal travel sensor, calculation module and judgement module can be integrated on the VCU of vehicle, alarm module can be for the well accuse screen of vehicle, also can be for the voice broadcast system of integration on the vehicle.
The calculation module comprises: a first barometric pressure threshold calculation module: the air pressure alarm threshold value is used for calculating the air pressure alarm threshold value when the brake pedal is in a free state and the vacuum pump is not started and/or is started; and the second air pressure threshold value calculating module is used for calculating an air pressure alarm threshold value when the vacuum pump is not started and/or started under the stepping state of the brake pedal.
The first air pressure threshold calculation module further comprises a first clock module for calculating a time period from a last complete release of the brake pedal.
The second barometric pressure threshold calculation module comprises:
a brake pedal stroke acquisition module: the system is used for acquiring the stroke of the brake pedal, which is acquired by a sensor on the vehicle;
a volume change calculation module: the volume change value of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank is calculated according to the stroke of the brake pedal;
a pressure change calculation module; the pressure change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank is calculated according to the volume change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank, the inner cavity volume of the vacuum booster diaphragm in a free state, the volume of the vacuum air storage tank and a first air pressure alarm threshold value;
the air pressure reduction rate calculation module: the air pressure reduction rate is calculated according to the current air pressure value of the vacuum air storage tank;
the air pressure drop change value calculation module: and calculating the air pressure reduction change value after the brake pedal is stepped down and the vacuum pump is started according to the air pressure reduction rate.
The air pressure drop change value calculation module further comprises a second clock module: and the method is used for acquiring the starting moment of the vacuum pump in the process of last stepping on the brake pedal.
One embodiment of the method of the present invention is described below, which comprises the steps of:
s1, collecting pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank, and completely releasing the brake pedal;
s2, calculating a first air pressure alarm threshold and a second air pressure alarm threshold corresponding to at least two different working conditions according to the information;
the first air pressure alarm threshold value corresponds to a threshold value of a brake pedal in a free state, and the calculation comprises the following steps: when the vacuum pump is not started, the first air pressure alarm threshold value is a first calibration value; when the vacuum pump works, the first air pressure alarm threshold value is a second calibration value.
The calculation of the first air pressure alarm threshold is further described below:
(1) when the vacuum pump is not started, the first air pressure alarm threshold value is a first calibration value and is marked as PV_offThe value can be 75KPa, but is not limited to this value;
(2) when the vacuum pump works, a second calibration value P is obtained according to the time length from the last time of completely releasing the brake pedalV_onAccording to the time t from the last complete release of the brake pedal as shown in table 1_reTo interpolate a look-up table. It can be seen that the second calibration is linearly related to the time since the last complete release of the brake pedal, and the second calibration decreases as the time since the last complete release of the brake pedal increases.
Considering that the previous braking operation causes outside air to enter the vacuum air storage tank, the vacuum pump needs a certain time to pump the air to reach the target air pressure threshold value. Therefore, the closer to the last time the brake pedal is released, the higher the air pressure threshold for diagnosing the vacuum shortage (high vacuum storage system air pressure, corresponding to low vacuum) is set. If braking is frequent, the shorter the brake pedal free-state hold time, the higher the corresponding diagnostic air pressure threshold. With t_reAnd increasing, and gradually reducing the set air pressure threshold. When t is_reWhen the set time is exceeded, the air pumping of the vacuum pump is supposed to reach a vacuum control target value, namely a threshold value PV_onWith 75Kpa, the set time period may be 9s, but is not limited to this value.
Thus, the first air pressure warning threshold P when the brake pedal is in a free statet1The calculation method comprises the following steps:
wherein, PV_onBy t_reAn interpolation look-up table, obtained according to table 1 below;
| t_re(s) | 0 | 0.5 | 1 | 2 | 3 | 4 | 5 | 7 | 9 | ≥10 |
| PV_on(Kpa) | 89 | 86.5 | 85 | 81 | 79 | 77.4 | 76.5 | 75.8 | 75.3 | 75 |
TABLE 1
The dynamic threshold value design considers the influence of the braking operation on the air pressure and also considers the dynamic change characteristic of the vacuum pumping air pressure.
The second air pressure alarm threshold value corresponds to a threshold value of a brake pedal in a treading state, and the calculation comprises the following steps:
s301, obtaining a volume change value delta V of a space formed by an inner cavity of the vacuum booster and the vacuum air storage tank according to the stroke of the brake pedal;
when the brake pedal is stepped, the volume formed by the inner cavity and the vacuum gas storage tank is compressed due to the movement of the diaphragm, and the air pressure in the vacuum gas storage tank is increased according to a gas state equation. The volume change caused by the movement of the diaphragm is Δ V. As the diaphragm is pushed by the brake pedal push rod, with a brake pedal stroke SBThe mapping yields Δ V. SBExpressed in percent, Δ V is obtained from the interpolation lookup table as a percentage of brake pedal travel, as shown in Table 2 below:
| SB(％) | 0 | 3 | 5 | 10 | 20 | 30 | 50 | 80 | 100 |
| ΔV(L) | 0 | 0.1 | 0.15 | 0.2 | 0.3 | 0.45 | 0.75 | 1.2 | 1.3 |
TABLE 2
S302, calculating a pressure change value delta P _ v of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank according to a volume change value of the space formed by the inner cavity of the vacuum booster and the vacuum air storage tank, the volume of the inner cavity of the vacuum booster diaphragm in a free state, the volume of the vacuum air storage tank and an air pressure value of the vacuum tank;
when the brake pedal is stepped on, according to the change of the volume, the pressure change value delta P _ v can be calculated by the following formula;
wherein L isapInner cavity container for vacuum booster diaphragm in free stateProduct, in this example, 1.8L; l isvcThe volume of the vacuum air storage tank is 3L in the embodiment; pt1_0The method is characterized in that the air pressure value of the vacuum tank is measured at the initial moment when the brake pedal is treaded for the last time, the initial moment is the initial moment when the brake pedal is started to be treaded and the stroke reaches 3 percent, and the moment is the initial moment.
S303, obtaining the air pressure reduction rate r according to the current air pressure value of the vacuum air storage tankp；
When the vacuum pump is started, the air pressure of the air storage tank is reduced by pumping air. The air suction capacity is related to the current air pressure of the vacuum air container, so that the air pressure value P passes through the current vacuum air containerm_vMapping the rate of pressure drop rp. In the present embodiment, rpThis can be mapped by interpolation lookup as in table 3 below:
TABLE 3
S304, calculating the air pressure reduction change value delta P after the brake pedal is stepped on and the vacuum pump is started according to the air pressure reduction ratep；
The change value delta P of the air pressure reduction caused by the starting of the vacuum pump when the brake pedal is pressedpCan be obtained by the following formula;
t0the time when the vacuum pump is started in the process of stepping down the brake pedal is indicated; and t is the current time.
When the brake pedal is stepped on, the push rod of the brake pedal translates to push the inner cavity air valve of the vacuum booster to close, and the outer cavity air valve is opened. At this time, the outer cavity of the vacuum booster is communicated with the outside atmosphere, the inner cavity is communicated with the vacuum gas storage tank, when the air pressure value of the vacuum gas storage tank reaches the starting threshold, the vacuum pump is started to pump the vacuum gas storage tank, and in the prior art, a plurality of setting methods are provided for the starting threshold of the vacuum pump, which are not described in the invention.
S305, according to the air pressure value of the vacuum tank, the pressure change value delta P _ v and the air pressure reduction change value delta P of the space formed by the inner cavity of the vacuum booster and the vacuum air storage tankpA second air pressure warning threshold is calculated.
A pressure threshold P for judging the lack of vacuum degree during the time of stepping on the brake pedalt2The calculation method of (2) is as follows:
in the formula Pof_2For offset, the value is 4KPa in this embodiment, but not limited to this value, Pt1_0The obtained air pressure value of the vacuum tank was measured for the time when the brake pedal was last depressed and the stroke reached 3%.
If the system is sealed well, the reasonable value of the air pressure drop caused by the braking operation is in accordance with the theory of observing the gas state equation. If the vacuum is insufficient, such as leakage, which causes the outside air to enter, the actual air pressure is increased by more than Δ PvWhen the pumping capacity of the vacuum pump is insufficient, the gas pressure is reduced at a rate slower than Δ PpThese can all be embodied in the threshold value Pt2In the dynamic range of (c).
And S3, when the air pressure of the vacuum air storage cavity is higher than or equal to the corresponding air pressure alarm threshold value in different states of the brake pedal, alarming to prompt that the vacuum degree of the current vacuum power assisting system is insufficient.
Namely when the brake pedal is in a free state, if the air pressure of the vacuum air storage cavity is higher than a first air pressure alarm threshold value Pt1If so, alarming to prompt that the vacuum degree is insufficient;
when the brake pedal is in a treading state, if the air pressure of the vacuum air storage cavity is higher than a second air pressure alarm threshold value Pt2If so, the alarm prompts that the vacuum degree is insufficient.
Claims (10)
1. A method for diagnosing a vacuum assist system for a vehicle, comprising the steps of:
s1, collecting pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank, and completely releasing the brake pedal;
s2, calculating a first air pressure alarm threshold and a second air pressure alarm threshold corresponding to at least two different working conditions according to the information;
and S3, under different working conditions, when the air pressure of the vacuum air storage tank is higher than or equal to the air pressure alarm threshold value under the corresponding working condition, alarming to prompt that the vacuum degree of the current vacuum boosting system is insufficient.
2. The method of claim 1, wherein the operating condition includes at least a brake pedal being free, and the calculating of the first barometric alarm threshold for the brake pedal being free comprises the steps of: when the vacuum pump is not started, the first air pressure alarm threshold value is a first calibration value; when the vacuum pump works, the first air pressure alarm threshold value is a second calibration value.
3. The method of claim 1, wherein the operating condition includes at least a brake pedal being depressed, and the calculating of the second air pressure warning threshold value includes the steps of:
s301, obtaining a volume change value of a space formed by an inner cavity of the vacuum booster and the vacuum air storage tank according to the stroke of the brake pedal;
s302, calculating a pressure change value delta P _ v of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank according to a volume change value of the space formed by the inner cavity of the vacuum booster and the vacuum air storage tank, the inner cavity volume of a diaphragm of the vacuum booster in a free state, the volume of the vacuum air storage tank and a first air pressure alarm threshold value;
s303, obtaining an air pressure reduction rate according to the air pressure value of the current vacuum air storage tank;
s304, calculating the air pressure reduction change value delta P after the brake pedal is stepped on and the vacuum pump is started according to the air pressure reduction ratep；
S305, according to a pressure change value delta P _ v and an air pressure reduction change value delta P of a space formed by an inner cavity of the vacuum booster and the vacuum air storage tankpA second air pressure warning threshold is calculated.
4. The diagnostic method of a vacuum assist system for a vehicle as set forth in claim 2, wherein the second calibration value is linearly related to a time since a last complete release of the brake pedal, the second calibration value decreasing with an increase in the time since the last complete release of the brake pedal.
5. The method for diagnosing a vacuum assist system for a vehicle according to claim 3, wherein the step S302 of calculating the pressure variation value Δ P _ v is performed by:
wherein L isapThe volume of the inner cavity of the vacuum booster diaphragm in a free state; l isvcIs the volume of the vacuum air storage tank; the delta V is a volume change value of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank due to the movement of the diaphragm; pt1_0The obtained air pressure value of the vacuum tank was measured for the time when the brake pedal was last depressed and the stroke reached 3%.
6. A diagnostic system for a vehicle vacuum assist system, comprising:
an acquisition module: the system is used for acquiring pressure information, outside air pressure information, brake pedal information and working state information of the vacuum air storage tank and the duration of completely loosening the brake pedal;
a calculation module: according to the information acquired by the acquisition module and the duration of releasing the brake pedal, calculating air pressure alarm thresholds under different working conditions;
a judging module: when the air pressure of the vacuum air storage cavity is higher than or equal to the air pressure alarm threshold under the corresponding working condition, the alarm module is started to give an alarm prompt;
an alarm module: the vacuum degree prompting device is used for prompting drivers and passengers to give an alarm to prompt that the vacuum degree of the current vacuum boosting system is insufficient.
7. The diagnostic system of a vehicle vacuum assist system as set forth in claim 7, wherein the calculation module includes:
a first barometric pressure threshold calculation module: the air pressure alarm threshold value is used for calculating the air pressure alarm threshold value when the brake pedal is in a free state and the vacuum pump is not started and/or is started;
and the second air pressure threshold value calculating module is used for calculating an air pressure alarm threshold value when the vacuum pump is not started and/or started under the stepping state of the brake pedal.
8. The diagnostic system of claim 8, wherein the first barometric threshold calculation module further comprises a first clock module configured to calculate a length of time until a last full brake pedal release.
9. The diagnostic system of claim 8, wherein the second air pressure threshold calculation module comprises:
a brake pedal stroke acquisition module: the system is used for acquiring the stroke of a brake pedal;
a volume change calculation module: the volume change value of a space formed by the inner cavity of the vacuum booster and the vacuum air storage tank is calculated according to the stroke of the brake pedal;
a pressure change calculation module; the pressure change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank is calculated according to the volume change value of the space formed by the vacuum booster inner cavity and the vacuum air storage tank, the inner cavity volume of the vacuum booster diaphragm in a free state, the volume of the vacuum air storage tank and a first air pressure alarm threshold value;
the air pressure reduction rate calculation module: the air pressure reduction rate is calculated according to the current air pressure value of the vacuum air storage tank;
the air pressure drop change value calculation module: and calculating the air pressure reduction change value after the brake pedal is stepped down and the vacuum pump is started according to the air pressure reduction rate.
10. The diagnostic system of a vacuum assist system for a vehicle of claim 8, wherein the air pressure drop change value calculation module further comprises a second clock module: and the method is used for acquiring the starting moment of the vacuum pump in the process of last stepping on the brake pedal.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115230668A (en) * | 2022-07-01 | 2022-10-25 | 北京汽车研究总院有限公司 | Leakage diagnosis method and device of vacuum booster, vehicle controller and vehicle |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1071945A (en) * | 1996-08-30 | 1998-03-17 | Nissan Motor Co Ltd | Emergency brake assist |
| CN103318165A (en) * | 2013-06-27 | 2013-09-25 | 奇瑞汽车股份有限公司 | Vacuum assistance system detection method, vacuum assistance system detection system, electromobile and failure detection method |
| CN104118420A (en) * | 2014-07-30 | 2014-10-29 | 重庆长安汽车股份有限公司 | Fault diagnosis method for blade electric vehicle vacuum assistance brake system |
| CN104309603A (en) * | 2014-09-30 | 2015-01-28 | 联合汽车电子有限公司 | Method for diagnosing air leakage of vacuum air suction system for providing vacuum degree of brake system |
| CN205573931U (en) * | 2016-03-25 | 2016-09-14 | 宝沃汽车（中国）有限公司 | Vacuum pump failure diagnosis processing system and vehicle that has this system |
| CN111591276A (en) * | 2020-05-09 | 2020-08-28 | 宜宾凯翼汽车有限公司 | Fault diagnosis and control method for automobile vacuum pump |
| CN111645664A (en) * | 2020-04-30 | 2020-09-11 | 湖南智点智能新能源汽车有限公司 | Electric vehicle fault analysis method, device and equipment and vehicle |
-
2021
- 2021-10-29 CN CN202111268870.3A patent/CN113954809B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1071945A (en) * | 1996-08-30 | 1998-03-17 | Nissan Motor Co Ltd | Emergency brake assist |
| CN103318165A (en) * | 2013-06-27 | 2013-09-25 | 奇瑞汽车股份有限公司 | Vacuum assistance system detection method, vacuum assistance system detection system, electromobile and failure detection method |
| CN104118420A (en) * | 2014-07-30 | 2014-10-29 | 重庆长安汽车股份有限公司 | Fault diagnosis method for blade electric vehicle vacuum assistance brake system |
| CN104309603A (en) * | 2014-09-30 | 2015-01-28 | 联合汽车电子有限公司 | Method for diagnosing air leakage of vacuum air suction system for providing vacuum degree of brake system |
| CN205573931U (en) * | 2016-03-25 | 2016-09-14 | 宝沃汽车（中国）有限公司 | Vacuum pump failure diagnosis processing system and vehicle that has this system |
| CN111645664A (en) * | 2020-04-30 | 2020-09-11 | 湖南智点智能新能源汽车有限公司 | Electric vehicle fault analysis method, device and equipment and vehicle |
| CN111591276A (en) * | 2020-05-09 | 2020-08-28 | 宜宾凯翼汽车有限公司 | Fault diagnosis and control method for automobile vacuum pump |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115230668A (en) * | 2022-07-01 | 2022-10-25 | 北京汽车研究总院有限公司 | Leakage diagnosis method and device of vacuum booster, vehicle controller and vehicle |
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