CN111071253B - Vehicle starting control method and hill hold system - Google Patents
Vehicle starting control method and hill hold system Download PDFInfo
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- CN111071253B CN111071253B CN201911379193.5A CN201911379193A CN111071253B CN 111071253 B CN111071253 B CN 111071253B CN 201911379193 A CN201911379193 A CN 201911379193A CN 111071253 B CN111071253 B CN 111071253B
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- vehicle
- ramp
- pressure
- slope
- pressure maintaining
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
- B60W30/18—Propelling the vehicle
- B60W30/18009—Propelling the vehicle related to particular drive situations
- B60W30/18027—Drive off, accelerating from standstill
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
- B60W30/18—Propelling the vehicle
- B60W30/18009—Propelling the vehicle related to particular drive situations
- B60W30/18109—Braking
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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
- B60T2201/00—Particular use of vehicle brake systems; Special systems using also the brakes; Special software modules within the brake system controller
- B60T2201/06—Hill holder; Start aid systems on inclined road
Abstract
The invention discloses a vehicle starting control method for a hill hold system, which comprises the following steps: when a vehicle is stationary on a slope, calculating a slope value of the vehicle, calculating minimum braking pressure required for keeping the vehicle stationary, selecting pressure maintaining pressure to perform a parking pressure maintaining value of a slope auxiliary system if a pressure maintaining condition is met, stepping down a brake pedal to enable the slope auxiliary system to maintain the parking pressure maintaining value, starting when the brake pedal is reset, enabling the slope auxiliary system to continuously maintain pressure for a first time period according to the parking pressure maintaining value, starting when an accelerator is stepped down, selecting a slope of pressure relief of the slope auxiliary system according to the working condition of the vehicle, and finishing pressure relief according to the selected slope of pressure relief until the pressure relief condition is met, thereby finishing vehicle starting. The invention also discloses a hill auxiliary system using the vehicle starting control method. The invention can achieve the same function and effect as 12 electromagnetic valves and a main cylinder pressure sensor in the prior art only by 10 electromagnetic valves, and reduces the production cost of the ramp auxiliary system.
Description
Technical Field
The invention relates to the field of automobiles, in particular to a vehicle starting control method. The invention also relates to a ramp assisting system.
Background
With the continuous development of the electric control technology of the automobile chassis, an electronic brake anti-lock braking system/electronic stability control system (ABS/ESC) is almost the standard configuration of all new automobiles. Aiming at a new vehicle configured by an electronic stability control system, because the electronic stability control system has pressure maintaining and active pressure building capabilities, a series of Value Added Functions (VAF) are developed around manufacturers of various parts of the electronic stability control system products to increase the market competitiveness of the products. The hill-hold system (HHC) is used for holding pressure of the wheel cylinders by two integrated valves, so that the vehicle cannot slide down when starting on a hill. At present, almost all ramp auxiliary systems in the market are developed by an electronic stability control system (including a master cylinder pressure sensor) based on at least 12 electromagnetic valves to realize ramp starting control, so that the cost is high, and a lot of challenges are brought to the cost control.
Disclosure of Invention
In this summary, a series of simplified form concepts are introduced that are simplifications of the prior art in this field, which will be described in further detail in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
The invention aims to solve the technical problem of providing a vehicle starting control method which can execute hill starting and pressure maintaining according to the actual working condition of a vehicle, realize linear hill starting assistance and prolong the time for avoiding slope slipping as far as possible under the condition of insufficient vehicle driving force.
The invention also provides a hill-hold system which can reduce the cost by using the vehicle starting control method compared with the prior art.
In order to solve the technical problem, the invention provides a vehicle starting control method for a hill hold system, which comprises the following steps:
s1, when the vehicle is at a standstill on a slope, calculating the value of the slope on which the vehicle is located;
s2, calculating the minimum braking pressure required for keeping the vehicle stationary according to the ramp value and the vehicle parameters; the vehicle parameters comprise two parameters of vehicle body mass, wheel force and master cylinder pressure conversion coefficient;
s3, if the pressure maintaining condition is met, taking the smaller one of the minimum braking pressure and the pressure maintaining braking pressure of the maximum ramp value allowed by the ramp auxiliary system as the parking pressure maintaining value of the ramp auxiliary system;
s3, the brake pedal is pressed down, so that the hill hold system maintains the parking pressure maintaining value;
s4, starting when the brake pedal begins to reset, enabling the ramp auxiliary system to keep pressure maintaining for a first time length according to the parking pressure maintaining value;
s5, selecting a slope of pressure relief of the slope auxiliary system according to the working condition of the vehicle when the accelerator is stepped on;
and S6, the slope auxiliary system finishes pressure relief according to the selected pressure relief slope until the pressure maintaining condition is met, and vehicle starting is finished.
When step S1 is executed, it is determined whether the vehicle state is stationary based on the wheel speed.
Alternatively, for example, the acceleration sensor signal of the TPMS system is utilized.
When step S2 is executed, the minimum brake pressure required to keep the vehicle stationary is calculated from the ramp value and the vehicle parameter.
Pmin＝mveh×g×sinθ×Cp
PminIs the minimum brake pressure, mvehThe vehicle body mass parameter, g, theta, and Cp are parameters of a conversion relationship between the wheel force and the master cylinder pressure.
In step S3, the pressure maintaining condition is required to satisfy all of the following conditions:
a) starting a ramp auxiliary system under pressure maintaining;
b) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
c) activating a pressure maintaining request by the ramp auxiliary system;
d) the vehicle is at rest;
e) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
f) the accelerator pedal is not depressed.
In step S4, the first time period is 1 second to 5 seconds. Preferably, the first period of time is 2 seconds.
In step S5, each vehicle operating condition corresponds to at least one pressure relief slope through calibration, and the vehicle operating conditions are divided as follows:
A) working conditions of flat ground;
B) the accelerator pedal is stepped on;
C) hill hold system failure, engine stall, or no driver;
D) the vehicle is positioned on a slope, and no other operation is performed on the vehicle after the brake pedal is reset.
In step S6, the pressure holding condition is any one of the following conditions;
1) driving the vehicle away;
2) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
the time threshold value is a time parameter that HHC can maintain pressure after the driver leaves the brake pedal;
3) the maximum pressure maintaining time of the ramp auxiliary system is reached;
the maximum pressure maintaining time is the maximum time that the HHC can continuously maintain the pressure after the driver steps on the brake pedal;
4) starting a manual brake;
5) the vehicle ignition key rotates to an initial position, namely an engine flameout position;
6) the ramp value is smaller than a preset ramp threshold;
7) the wheel is slipped;
8) a ramp assist system failure;
9) the driver is not in the driving position.
Optionally, the control method of the vehicle slope auxiliary system is further improved, and if the accelerator pedal is pressed down and the maximum pressure holding time of the slope auxiliary system is reached, the pressure relief slope is reduced until the lower limit of the pressure relief slope is reached. If the driver steps on an accelerator pedal, but the driving torque is not enough all the time, the condition of quitting pressure maintaining can not be met all the time, once the time is long enough, the condition of meeting the subsequent maximum pressure maintaining time is caused, the pressure relief stage can be shifted to, at the moment, the corresponding slope is calculated according to the input of the corresponding driving torque of the driver, if the driving torque of the engine is not enough all the time, the slope is correspondingly reduced, the pressure maintaining time can be properly prolonged by adding the previous pressure maintaining time, the robustness is increased, but the slope calculation also has a lower limit value, if the final driving torque of the engine is not moved up all the time, the pressure can be finally released to 0, and the situation of slope slipping occurs, which belongs to the normal.
The invention provides a hill assistance system of the vehicle starting control method, which comprises the following steps:
the pedal is used for outputting braking pressure to each tire according to a braking request of the pedal and transmitting the braking pressure to each tire through a braking pipeline;
the acceleration sensor is used for acquiring the acceleration of the tire and sending the acceleration to the controller;
alternatively, the acceleration sensor may be an acceleration sensor of the TPMS system without increasing the cost.
The controller is used for calculating the minimum braking pressure required for keeping the vehicle static according to the ramp value and the vehicle parameters and driving each electromagnetic valve to complete pressure maintaining;
alternatively, the controller may be an electronic brake anti-lock braking system/electronic stability control system (ABS/ESC) controller (or, alternatively, a stand-alone embedded controller). And, the following first to tenth battery valves are all the existing electronic braking anti-lock braking system/electronic stability control system (ABS/ESC) battery valves.
A first solenoid valve EV1 connected between the left rear wheel cylinder and a ninth solenoid valve USV 1;
a second solenoid valve AV1 connected between the left rear wheel cylinder and the low pressure accumulator;
a third electromagnetic valve EV2 connected between the right front wheel cylinder and a ninth electromagnetic valve USV 1;
a fourth electromagnetic valve AV2 connected between the right front wheel cylinder and the low pressure accumulator;
a fifth electromagnetic valve EV3 connected between the front left wheel cylinder and a tenth electromagnetic valve USV 2;
a sixth electromagnetic valve AV3 connected between the front left wheel cylinder and the low-pressure accumulator;
a seventh electromagnetic valve EV4 connected between the right rear wheel cylinder and the tenth electromagnetic valve USV 2;
an eighth electromagnetic valve AV4 connected between the right rear wheel cylinder and the low-pressure accumulator;
a ninth solenoid valve USV1 connected between the master cylinder MC1 and the first and third solenoid valves EV1 and EV2,
a tenth solenoid valve USV2 connected between the master cylinder MC1 and the valves of the fifth and seventh solenoid valves EV3 and EV 4;
the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, the fifth electromagnetic valve, the sixth electromagnetic valve and the eighth electromagnetic valve are opened when the ABS function of the anti-lock brake system works, closed when the ABS of the anti-lock brake system exits, opened only when the ABS of the anti-lock brake system works, and not opened when the HHC;
the ninth solenoid valve USV1 and the tenth solenoid valve USV2 are opened when the hill assist system HHC is operating, and are closed after the hill assist system HHC is withdrawn. In the working process of the ramp auxiliary system HHC, the ninth electromagnetic valve USV1 and the tenth electromagnetic valve USV2 are in an electrified closing state, and a hydraulic circuit cuts off the flow of hydraulic oil between the wheel cylinder and the master cylinder, so that the hydraulic oil in the wheel cylinder is prevented from flowing back to the master cylinder, and the pressure maintaining is realized;
alternatively, the hill assist system may be further improved wherein the controller determines whether the vehicle state is stationary based on wheel speed.
Optionally, calculating the minimum braking pressure required for keeping the vehicle stationary according to the ramp value and the vehicle parameters;
Pmin＝mveh×g×sinθ×Cp
Pminis the minimum brake pressure, mvehThe vehicle body mass parameter, g, theta, and Cp are parameters of a conversion relationship between the wheel force and the master cylinder pressure.
Optionally, the controller enters the pressure maintaining condition to satisfy all the following conditions:
a) starting a ramp auxiliary system under pressure maintaining;
b) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
c) activating a pressure maintaining request by the ramp auxiliary system;
d) the vehicle is at rest;
e) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
f) the accelerator pedal is not depressed.
Optionally, the first time period is 1 second to 5 seconds. Preferably, the first period of time is 2 seconds.
Alternatively, the controller may classify the vehicle operating conditions as follows:
A) working conditions of flat ground;
B) the accelerator pedal is stepped on;
C) hill hold system failure, engine stall, or no driver;
D) the vehicle is positioned on a slope, and the vehicle has no other operation after the brake pedal is reset;
and each vehicle working condition is calibrated to correspond to at least one pressure relief slope controller to control each battery valve to relieve pressure according to the pressure relief slope.
Optionally, the controller exits from the pressure maintaining condition to be any one of the following working conditions;
1) driving the vehicle away;
2) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
the time threshold value is a time parameter that HHC can maintain pressure after the driver leaves the brake pedal;
3) the maximum pressure maintaining time of the ramp auxiliary system is reached;
the maximum pressure maintaining time is the maximum time that the HHC can continuously maintain the pressure after the driver steps on the brake pedal;
4) starting a manual brake;
5) the vehicle ignition key rotates to an initial position, namely an engine flameout position;
6) the ramp value is smaller than a preset ramp threshold;
7) the wheel is slipped;
8) a ramp assist system failure;
9) the driver is not in the driving position.
Alternatively, if the accelerator pedal is depressed and the maximum dwell time of the hill assist system is reached, the controller decreases the slope of the pressure relief until the lower limit of the slope of the pressure relief is reached.
The invention provides a scheme for realizing a hill start assisting function without depending on a master cylinder pressure sensor. This solution can assist the driver in hill starts by maintaining the pressure built up during braking to allow the driver to release the brake pedal after the vehicle is stationary. When the driver depresses the accelerator pedal, the previously built pressure will be released and the vehicle can accelerate and drive away. The main requirements of the present invention to trigger the hill assist function are the signal input from the vehicle braking to rest and the driver depressing the brake pedal. The slope auxiliary function utilizes an internal longitudinal acceleration sensor to calculate slope information of the current position of the vehicle in real time in the static state of the vehicle, the minimum braking pressure required for enabling the current vehicle not to slide down the slope can be estimated through the slope information, pressure maintaining control is carried out on the current wheel cylinder pressure through an electromagnetic valve according to the calculated minimum pressure value, after a driver releases a brake pedal, the brake pressure input by the driver when the driver brakes and enables the vehicle to keep static is kept in a brake system by the longitudinal acceleration sensor function according to the calculated pressure maintaining value. The brake pressure will start to release after the dwell (at most 2 s). During the pressure holding period, the driver has enough time to step on the accelerator to start driving away. The brake pressure will also slowly release to decrease once the system detects the driver's intent to take off. The driver's intention to start is determined by whether the engine torque can be started in a desired direction. However, if the driver depresses the accelerator pedal but the engine fails to output sufficient torque, the dwell time will be automatically extended. In addition to the above, if the driver does not depress either the accelerator pedal or the brake pedal during the hold pressure after releasing the brake pedal, the longitudinal acceleration sensor function will be terminated after the hold pressure is ended, and the vehicle will therefore roll back.
Referring to fig. 1, which is a hydraulic schematic diagram of the present invention, after a driver drives a vehicle on a slope to stop the vehicle by braking, a vehicle speed Vx is 0m/s, a vehicle stop time is t1, and a brake pedal depression time is t 0; after the vehicle is stopped on a slope, the slope auxiliary system can judge that the Standstill state of the vehicle is legal according to four wheel speeds, and meanwhile, the slope auxiliary system can calculate the minimum brake pressure Pslope for keeping the vehicle not to slide down the slope according to slope information provided by a longitudinal acceleration sensor; after the ramp auxiliary system judges that the pressure maintaining condition for pressure maintaining is met, the minimum value is taken according to Pslope and the pressure maintaining braking force Pmax of the maximum ramp allowed by the electromagnetic valve, and the electromagnetic valve is driven to perform pressure maintaining operation (corresponding current is conducted to the integrated valve); the driver steps on the brake pedal on the slope, the HHC drives the electromagnetic valve to maintain pressure, and the time is t2 when the driver decides to start and leave and the foot leaves the brake pedal; the ramp auxiliary system keeps maintaining the pressure after the time t2, the maximum time is 2s, and the driver can drive off by stepping on the accelerator within the 2s time; the driver steps on the throttle and drives away from the in-process, and drive power lasts the increase, and ramp auxiliary system can calculate suitable pressure release slope according to current state this moment, guarantees that the vehicle starting process is smooth-going stable, and not adhesion, not back swift current have four kinds of pressure release slopes altogether: 1) working conditions of flat ground; 2) when a driver steps on an accelerator pedal to start, the pressure relief rate needs to be converted according to different driving forces; 3) HHC fault exit or engine stall or driver absence; 4) the driver on the slope does not take other operations or other remaining operating conditions after releasing the brake pedal. The above four pressure relief slopes achieve different pressure relief rates by controlling the opening degrees of the ninth solenoid valve USV1 and the tenth solenoid valve USV2 when they are opened. If the driver steps on the accelerator pedal, but the driving torque is not enough all the time, the condition of quitting the pressure maintaining is not met all the time, once the time is long enough, the subsequent maximum pressure maintaining time meets the condition, the algorithm state can be switched to a pressure relief stage, at the moment, a corresponding slope is calculated according to the input of the corresponding driving torque of the driver, if the driving torque of the engine is not enough all the time, the slope is correspondingly reduced, the pressure maintaining time is properly prolonged by adding the previous pressure maintaining time, so the algorithm is optimized, the robustness of the HHC function is increased, the slope calculation also has a lower limit value, if the driving torque of the engine cannot be moved all the time finally, the pressure can be finally released to 0, and the slope slipping condition occurs, which belongs to the normal phenomenon.
T 3-t 2 is the HHC dwell time (automatic gear 1s, manual gear 2s) after the brake pedal is released, t 3-t 1 is the Tmax HHC USV (integrated valve) valve dwell time longest and is set to 20s, the USV energization current gives the maximum dwell pressure Pmax of 60bar (30% ramp is calculated), the starting dwell pressure Pslop is converted according to ramp information, the integrated valve dwell force is set, the minimum value Pusv of the two values is min (Pslop + P, Pmax), the engine Torque Eng _ Torque is greater than the starting Torque F _ op, and then the integrated valve dwell force converts the pressure relief slope according to the pressure relief type to ensure functional comfort. Compared with the traditional ESC (electronic stability control) hydraulic schematic diagram, the technical scheme of the invention only depends on the combination of 10 solenoid valves (four EV valves, four AV valves and two USV valves) and longitudinal tire sensor signals (estimated ramps) integrated on a circuit board to realize hill start assistance. It should be noted that four EV valves and four AV valves are provided to ensure ABS functionality, and that the ramp assist function does not require EV valves and AV valves to operate, but that the 10 solenoid valves described above are essential for the integrity of the ramp assist function.
The invention realizes the ramp auxiliary function under the condition of only depending on 10 electromagnetic valves on the premise of no main cylinder pressure sensor and no HSV valve. Meanwhile, the function can achieve the same function and effect as the slope starting auxiliary function of the standard 12 electromagnetic valves and the master cylinder pressure sensor, the same function is achieved, the cost is reduced, and obvious economic benefits are achieved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification. The drawings are not necessarily to scale, however, and may not be intended to accurately reflect the precise structural or performance characteristics of any given embodiment, and should not be construed as limiting or restricting the scope of values or properties encompassed by exemplary embodiments in accordance with the invention. The invention will be described in further detail with reference to the following detailed description and accompanying drawings:
fig. 1 is a hydraulic schematic of the present invention.
FIG. 2 is a schematic view of the ramp assist system of the present invention.
Description of the reference numerals
Vx vehicle speed
t0 time Point of BLS (brake pedal switch Signal) Down trigger
t1 time point of vehicle standstill
t2 time Point of BLS Release
t3 time Point when pressure maintaining ended and vehicle began to roll backwards
WC1 to WC4 represent four wheel cylinders.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and technical effects of the present invention will be fully apparent to those skilled in the art from the disclosure in the specification. The invention is capable of other embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the general spirit of the invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. The following exemplary embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the technical solutions of these exemplary embodiments to those skilled in the art.
The invention provides a first embodiment of a vehicle starting control method for a hill-assist system, which comprises the following steps:
s1, when the vehicle is at a standstill on a slope, calculating the value of the slope on which the vehicle is located;
s2, calculating the minimum braking pressure required for keeping the vehicle stationary according to the ramp value and the vehicle parameters;
Pmin＝mveh×g×sinθ×Cp
Pminis the minimum brake pressure, mvehThe vehicle body mass parameter, g, theta, and Cp are parameters of a conversion relationship between the wheel force and the master cylinder pressure.
S3, if the pressure maintaining condition is met, taking the smaller one of the minimum braking pressure and the pressure maintaining braking pressure of the maximum ramp value allowed by the ramp auxiliary system as the parking pressure maintaining value of the ramp auxiliary system; the entering pressure maintaining condition needs to satisfy all the following working conditions:
a) starting a ramp auxiliary system under pressure maintaining;
b) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
c) activating a pressure maintaining request by the ramp auxiliary system;
d) the vehicle is at rest;
e) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
f) the accelerator pedal is not stepped on;
s3, the brake pedal is pressed down, so that the hill hold system maintains the parking pressure maintaining value;
s4, starting when the brake pedal begins to reset, enabling the ramp auxiliary system to keep pressure maintaining for a first time length according to the parking pressure maintaining value;
s5, selecting a slope of pressure relief of the slope auxiliary system according to the working condition of the vehicle when the accelerator is stepped on; each vehicle working condition corresponds to at least one pressure relief slope through calibration, and the vehicle working conditions are divided into the following parts:
A) working conditions of flat ground;
B) the accelerator pedal is stepped on;
C) hill hold system failure, engine stall, or no driver;
D) the vehicle is positioned on a slope, and the vehicle has no other operation after the brake pedal is reset;
s6, the ramp auxiliary system finishes pressure relief according to the selected pressure relief slope until the pressure maintaining condition is met, and vehicle starting is finished; the pressure maintaining condition is any one of the following working conditions;
1) driving the vehicle away;
2) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
the time threshold value is a time parameter that HHC can maintain pressure after the driver leaves the brake pedal;
3) the maximum pressure maintaining time of the ramp auxiliary system is reached;
the maximum pressure maintaining time is the maximum time that the HHC can continuously maintain the pressure after the driver steps on the brake pedal;
4) starting a manual brake;
5) the vehicle ignition key rotates to an initial position, namely an engine flameout position;
6) the ramp value is smaller than a preset ramp threshold;
7) the wheel is slipped;
8) a ramp assist system failure;
9) the driver is not in the driving position.
When step S1 is executed, it is determined whether the vehicle state is stationary based on the wheel speed. The first time length is 1-5 seconds, and the automatic gear is preferably 1s, and the manual gear is preferably 2 s.
The invention provides a first embodiment of a hill assistance system of a vehicle starting control method, which comprises the following steps:
the pedal is used for outputting braking pressure to each tire according to a braking request of the pedal and transmitting the braking pressure to each tire through a braking pipeline;
the acceleration sensor is used for acquiring the acceleration of the tire and sending the acceleration to the controller;
alternatively, the acceleration sensor may be an acceleration sensor of the TPMS system without increasing the cost.
The controller is used for calculating the minimum braking pressure required for keeping the vehicle static according to the ramp value and the vehicle parameters and driving each electromagnetic valve to complete pressure maintaining; the controller calculates the minimum braking pressure required for keeping the vehicle static according to the ramp value and the vehicle parameters;
Pmin＝mveh×g×sinθ×Cp
Pminis the minimum brake pressure, mvehThe vehicle body mass parameter, g, theta, and Cp are parameters of a conversion relationship between the wheel force and the master cylinder pressure.
The controller enters the pressure maintaining condition to meet all the following working conditions:
a) starting a ramp auxiliary system under pressure maintaining;
b) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
c) activating a pressure maintaining request by the ramp auxiliary system;
d) the vehicle is at rest;
e) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
f) the accelerator pedal is not depressed.
The controller divides the vehicle operating conditions as follows:
A) working conditions of flat ground;
B) the accelerator pedal is stepped on;
C) hill hold system failure, engine stall, or no driver;
D) the vehicle is positioned on a slope, and the vehicle has no other operation after the brake pedal is reset;
and each vehicle working condition is calibrated to correspond to at least one pressure relief slope controller to control each battery valve to relieve pressure according to the pressure relief slope.
The controller exits the pressure maintaining condition to be any one of the following working conditions;
1) driving the vehicle away;
2) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
the time threshold value is a time parameter that HHC can maintain pressure after the driver leaves the brake pedal;
3) the maximum pressure maintaining time of the ramp auxiliary system is reached;
the maximum pressure maintaining time is the maximum time that the HHC can continuously maintain the pressure after the driver steps on the brake pedal;
4) starting a manual brake;
5) the vehicle ignition key is rotated to an initial position;
6) the ramp value is smaller than a preset ramp threshold;
7) the wheel is slipped;
8) a ramp assist system failure;
9) the driver is not in the driving position.
Alternatively, the controller may be an electronic brake anti-lock braking system/electronic stability control system (ABS/ESC) controller. And, the following first to tenth battery valves are all the existing electronic braking anti-lock braking system/electronic stability control system (ABS/ESC) battery valves.
A first solenoid valve EV1 connected between the left rear wheel cylinder and a ninth solenoid valve USV 1;
a second solenoid valve AV1 connected between the left rear wheel cylinder and the low pressure accumulator;
a third electromagnetic valve EV2 connected between the right front wheel cylinder and a ninth electromagnetic valve USV 1;
a fourth electromagnetic valve AV2 connected between the right front wheel cylinder and the low pressure accumulator;
a fifth electromagnetic valve EV3 connected between the front left wheel cylinder and a tenth electromagnetic valve USV 2;
a sixth electromagnetic valve AV3 connected between the front left wheel cylinder and the low-pressure accumulator;
a seventh electromagnetic valve EV4 connected between the right rear wheel cylinder and the tenth electromagnetic valve USV 2;
an eighth electromagnetic valve AV4 connected between the right rear wheel cylinder and the low-pressure accumulator;
a ninth solenoid valve USV1 connected between the master cylinder MC1 and the first and third solenoid valves EV1 and EV2,
a tenth solenoid valve USV2 connected between the master cylinder MC1 and the valves of the fifth and seventh solenoid valves EV3 and EV 4;
the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, the fifth electromagnetic valve, the sixth electromagnetic valve and the eighth electromagnetic valve are opened when the ABS function of the anti-lock brake system works, closed when the ABS of the anti-lock brake system exits, opened only when the ABS of the anti-lock brake system works, and not opened when the HHC;
the ninth solenoid valve USV1 and the tenth solenoid valve USV2 are opened when the hill assist system HHC is operating, and are closed after the hill assist system HHC is withdrawn. In the working process of the ramp auxiliary system HHC, the ninth electromagnetic valve USV1 and the tenth electromagnetic valve USV2 are in an electrified closing state, and a hydraulic circuit cuts off the flow of hydraulic oil between the wheel cylinder and the master cylinder, so that the hydraulic oil in the wheel cylinder is prevented from flowing back to the master cylinder, and the pressure maintaining is realized;
wherein the first time period is 1 second to 5 seconds. Preferably, the first period of time is 2 seconds. If the accelerator pedal is stepped on and the maximum pressure maintaining time of the ramp auxiliary system is reached, the controller reduces the pressure relief slope until the lower limit of the pressure relief slope is reached.
Further, it will be understood that, although the terms first, second, etc. may be used herein to describe various elements, parameters, components, regions, layers and/or sections, these elements, parameters, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, parameter, component, region, layer or section from another element, parameter, component, region, layer or section. Thus, a first element, parameter, component, region, layer or section discussed below could be termed a second element, parameter, component, region, layer or section without departing from the teachings of exemplary embodiments according to the present invention.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The present invention has been described in detail with reference to the specific embodiments and examples, but these are not intended to limit the present invention. Many variations and modifications may be made by one of ordinary skill in the art without departing from the principles of the present invention, which should also be considered as within the scope of the present invention.
Claims (18)
1. A vehicle starting control method for a hill hold system is characterized by comprising the following steps:
s1, when the vehicle is at a standstill on a slope, calculating the value of the slope on which the vehicle is located;
s2, calculating the minimum braking pressure required for keeping the vehicle stationary according to the ramp value and the vehicle parameters;
s3, if the pressure maintaining condition is met, taking the smaller one of the minimum braking pressure and the pressure maintaining braking pressure of the maximum ramp value allowed by the ramp auxiliary system as the parking pressure maintaining value of the ramp auxiliary system;
s3, the brake pedal is pressed down, so that the hill hold system maintains the parking pressure maintaining value;
s4, starting when the brake pedal begins to reset, enabling the ramp auxiliary system to keep pressure maintaining for a first time length according to the parking pressure maintaining value;
s5, selecting a slope of pressure relief of the slope auxiliary system according to the working condition of the vehicle when the accelerator is stepped on;
and S6, the slope auxiliary system finishes pressure relief according to the selected pressure relief slope until the pressure maintaining condition is met, and vehicle starting is finished.
2. The vehicle startup control method according to claim 1, characterized in that: when step S1 is performed, it is determined whether the vehicle state is stationary based on the wheel speed.
3. The vehicle startup control method according to claim 1, characterized in that: when step S2 is implemented, the minimum braking pressure required for keeping the vehicle stationary is calculated according to the ramp value and the vehicle parameters, and the formula is as follows;
4. The vehicle startup control method according to claim 1, characterized in that: in step S3, the pressure maintaining condition should satisfy all of the following conditions:
1) starting a ramp auxiliary system under pressure maintaining;
2) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
3) activating a pressure maintaining request by the ramp auxiliary system;
4) the vehicle is at rest;
5) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
6) the accelerator pedal is not depressed.
5. The vehicle startup control method according to claim 1, characterized in that: in step S4, the first time period is 1 second to 5 seconds.
6. The vehicle startup control method according to claim 5, characterized in that: the first time period is 2 seconds.
7. The vehicle startup control method according to claim 1, characterized in that: in step S5, each vehicle operating condition corresponds to at least one pressure relief slope by calibration, and the vehicle operating conditions are divided as follows:
1) working conditions of flat ground;
2) the accelerator pedal is stepped on;
3) hill hold system failure, engine stall, or no driver;
4) the vehicle is positioned on a slope, and no other operation is performed on the vehicle after the brake pedal is reset.
8. The vehicle startup control method according to claim 1, characterized in that: in step S6, the pressure maintaining condition is any one of the following conditions;
5) driving the vehicle away;
6) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
7) the maximum pressure maintaining time of the ramp auxiliary system is reached;
8) starting a manual brake;
9) the vehicle ignition key is rotated to an initial position;
10) the ramp value is smaller than a preset ramp threshold;
11) the wheel is slipped;
12) a ramp assist system failure;
13) the driver is not in the driving position.
9. The vehicle startup control method according to claim 8, characterized in that: and if the accelerator pedal is stepped on and the maximum pressure maintaining time of the ramp auxiliary system is reached, reducing the pressure relief slope until the lower limit of the pressure relief slope is reached.
10. A hill assist system using the vehicle starting control method according to claim 1, characterized by comprising ten solenoids, a pedal, an acceleration sensor, and a controller:
the pedal is used for outputting braking pressure to each tire according to a braking request of the pedal and transmitting the braking pressure to each tire through a braking pipeline;
the acceleration sensor is used for acquiring the acceleration of the tire and sending the acceleration to the controller;
the controller is used for calculating the minimum braking pressure required for keeping the vehicle static according to the ramp value and the vehicle parameters and driving each electromagnetic valve to complete pressure maintaining;
a first solenoid valve (EV 1) connected between the left rear wheel cylinder and a ninth solenoid valve (USV 1);
a second solenoid valve (AV 1) connected between the left rear wheel cylinder and the low pressure accumulator;
a third electromagnetic valve (EV 2) connected between the right front wheel cylinder and a ninth electromagnetic valve (USV 1);
a fourth electromagnetic valve (AV 2) connected between the right front wheel cylinder and the low pressure accumulator;
a fifth electromagnetic valve (EV 3) connected between the front left wheel cylinder and a tenth electromagnetic valve (USV 2);
a sixth electromagnetic valve (AV 3) connected between the front left wheel cylinder and the low-pressure accumulator;
a seventh electromagnetic valve (EV 4) connected between the right rear wheel cylinder and a tenth electromagnetic valve (USV 2);
an eighth electromagnetic valve (AV 4) connected between the right rear wheel cylinder and the low-pressure accumulator;
a ninth solenoid valve (USV 1) connected between the master cylinder (MC 1) and the first (EV 1) and third (EV 2) solenoid valves,
a tenth solenoid valve (USV 2) connected between the master cylinder (MC 1) and the valves of the fifth (EV 3) and seventh (EV 4) solenoid valves;
the first electromagnetic valve, the second electromagnetic valve, the third electromagnetic valve, the fourth electromagnetic valve, the fifth electromagnetic valve, the sixth electromagnetic valve and the eighth electromagnetic valve are respectively opened when the anti-lock braking system (ABS) functions work, closed when the anti-lock braking system (ABS) quits, opened only when the anti-lock braking system (ABS) works, and not opened when the ramp auxiliary system (HHC) works;
the ninth solenoid valve (USV 1) and the tenth solenoid valve (USV 2) are opened when the hill support system (HHC) is operated, and are closed after the hill support system (HHC) is withdrawn.
11. The ramp assist system according to claim 10, wherein: the controller determines whether the vehicle state is stationary based on the wheel speed.
12. The ramp assist system according to claim 10, wherein: calculating the minimum braking pressure required for keeping the vehicle stationary according to the ramp value and the vehicle parameters;
13. The ramp assist system according to claim 10, wherein: the controller enters the pressure maintaining condition to meet all the following working conditions:
a) starting a ramp auxiliary system under pressure maintaining;
b) the pressure maintaining pressure is greater than the component force of the gravity of the vehicle body along the ramp;
c) activating a pressure maintaining request by the ramp auxiliary system;
d) the vehicle is at rest;
e) the ramp value is greater than the minimum ramp threshold value of the ramp auxiliary system;
f) the accelerator pedal is not depressed.
14. The ramp assist system according to claim 10, wherein: the first time period is 1 second to 5 seconds.
15. The ramp assist system according to claim 14, wherein: the first time period is 2 seconds.
16. The ramp assist system according to claim 10, wherein: the controller divides the vehicle operating conditions as follows:
A) working conditions of flat ground;
B) the accelerator pedal is stepped on;
C) hill hold system failure, engine stall, or no driver;
D) the vehicle is positioned on a slope, and the vehicle has no other operation after the brake pedal is reset;
and each vehicle working condition is calibrated to correspond to at least one pressure relief slope controller to control each battery valve to relieve pressure according to the pressure relief slope.
17. The ramp assist system according to claim 10, wherein: the controller exits the pressure maintaining condition to be any one of the following working conditions;
1) driving the vehicle away;
2) the pressure maintaining time of the ramp auxiliary system reaches a time threshold value;
3) the maximum pressure maintaining time of the ramp auxiliary system is reached;
4) starting a manual brake;
5) the vehicle ignition key is rotated to an initial position;
6) the ramp value is smaller than a preset ramp threshold;
7) the wheel is slipped;
8) a ramp assist system failure;
9) the driver is not in the driving position.
18. The ramp assist system according to claim 17, wherein: if the accelerator pedal is stepped on and the maximum pressure maintaining time of the ramp auxiliary system is reached, the controller reduces the pressure relief slope until the lower limit of the pressure relief slope is reached.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911379193.5A CN111071253B (en) | 2019-12-27 | 2019-12-27 | Vehicle starting control method and hill hold system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911379193.5A CN111071253B (en) | 2019-12-27 | 2019-12-27 | Vehicle starting control method and hill hold system |
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| CN111071253A CN111071253A (en) | 2020-04-28 |
| CN111071253B true CN111071253B (en) | 2021-06-04 |
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| CN113619547A (en) * | 2021-09-10 | 2021-11-09 | 安徽江淮汽车集团股份有限公司 | Brake pressure valve for assisting in preventing vehicle from sliding down slope and control method for preventing vehicle from sliding down slope |
| CN114906117B (en) * | 2022-03-30 | 2023-07-04 | 阿尔特汽车技术股份有限公司 | Method, device, equipment and medium for determining brake pedal state of vehicle |
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| CN101778749A (en) * | 2007-04-19 | 2010-07-14 | 雷诺股份公司 | Hill start assistance method and associated device |
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| US6086515A (en) * | 1995-07-13 | 2000-07-11 | Itt Manufacturing Enterprises Inc. | Process and system for retaining a vehicle on an inclined roadway |
| CN101778749A (en) * | 2007-04-19 | 2010-07-14 | 雷诺股份公司 | Hill start assistance method and associated device |
| CN102358273A (en) * | 2011-09-01 | 2012-02-22 | 东风汽车有限公司 | Hill starting control device used under driving and parking braking and using method thereof |
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