CN114347968B - EPB release compensation control method and device and vehicle - Google Patents
EPB release compensation control method and device and vehicle Download PDFInfo
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- CN114347968B CN114347968B CN202210044232.1A CN202210044232A CN114347968B CN 114347968 B CN114347968 B CN 114347968B CN 202210044232 A CN202210044232 A CN 202210044232A CN 114347968 B CN114347968 B CN 114347968B
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Abstract
The embodiment of the invention discloses an EPB release compensation control method, an EPB release compensation control device and a vehicle. The EPB release compensation control method comprises the following steps: determining a wheel cylinder pressure, and determining a compensation amount for EPB release according to the wheel cylinder pressure; determining the total stroke of EPB release according to the released compensation amount; acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point, and determining the release speed of the piston according to the voltage value and the current value; calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release; the EPB release stroke is compensated according to the piston release time and the piston release speed. The embodiment of the invention can realize the effective release of the EPB under large brake pressure, and is beneficial to relieving the dragging problem of the vehicle.
Description
Technical Field
The embodiment of the invention relates to the technical field of vehicle braking, in particular to an EPB release compensation control method and device and a vehicle.
Background
In the automotive field, an Electronic Parking Brake (EPB) system can not only provide safety for a vehicle, but also provide driving assistance for a driver, such as automatically releasing a Brake when the vehicle is started, or implementing hill control when an inclined slope is started.
However, in the process of releasing the parking brake of an actual vehicle, in order to avoid the occurrence of vehicle damage, serious personal injury and even death accident, a driver needs to step on the brake pedal to release the parking. At this moment, EPB calliper piston receives the oil pressure propelling movement influence, will lead to EPB release not in place under big brake pressure, and then causes the vehicle to drag scheduling problem.
Disclosure of Invention
The embodiment of the invention provides an EPB release compensation control method, an EPB release compensation control device and a vehicle, which are used for realizing effective release of EPB under large brake pressure and are beneficial to relieving the dragging problem of the vehicle.
In a first aspect, an embodiment of the present invention provides an EPB release compensation control method, including:
determining a wheel cylinder pressure, and determining a compensation amount for EPB release according to the wheel cylinder pressure;
determining the total stroke of EPB release according to the released compensation amount;
acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point, and determining the release speed of the piston according to the voltage value and the current value;
calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release;
and compensating the EPB release stroke according to the piston release time and the piston release speed.
Alternatively, determining the compensation amount for EPB release from the wheel cylinder pressure includes:
and acquiring the compensation amount released by the EPB according to the wheel cylinder pressure lookup table.
Optionally, when the wheel cylinder pressure is larger than a preset value, the larger the wheel cylinder pressure is, the larger the compensation amount corresponding to the wheel cylinder pressure is; when the wheel cylinder pressure is smaller than the preset value, the compensation amount corresponding to the wheel cylinder pressure is zero.
Optionally, determining a total stroke of EPB release according to the released compensation amount includes:
determining the total stroke of EPB release according to the compensation quantity, the reference quantity and the safety quantity;
wherein the reference amount is a reference stroke of EPB release when the wheel cylinder pressure is zero and the disc just separates, and the safety amount is a safety stroke of EPB release provided to prevent the disc from contacting when the wheel cylinder pressure is zero and the disc just separates.
Alternatively, acquiring a voltage value and a current value of a motor for driving the piston at the disk separation point, and determining the piston release speed according to the voltage value and the current value, comprises:
acquiring an original value and a fluctuation value of the motor current;
when the original value and the fluctuation value meet the preset condition, determining the disc separation, wherein the original value is the current value of the disc separation point;
acquiring a voltage value corresponding to a disk separation point;
and calculating a first piston release speed according to the voltage value, calculating a second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
Optionally, when the original value and the fluctuation value satisfy a preset condition, determining the disc separation includes:
and confirming the separation of the disk when the initial value is not greater than a first current preset value and the fluctuation value is not greater than a second current preset value.
Optionally, obtaining the raw and fluctuating values of the motor current comprises:
taking the motor current at the current moment as an original value of the motor current;
taking a preset duration as a period, and taking the average value of the motor current of the preset period number before the current moment as a motor current input value;
obtaining the maximum value and the minimum value of the preset number of motor current input values before the current moment;
and taking the absolute value of the difference value between the maximum value and the minimum value of the motor current input value as the fluctuation value of the motor current.
Alternatively, determining the wheel cylinder pressure includes:
continuously judging whether the monitoring pressure of the wheel cylinder is credible or not within preset monitoring time;
continuously acquiring the maximum value of the wheel cylinder monitoring pressure in the current period;
and continuously comparing the maximum value of the wheel cylinder monitoring pressure with the wheel cylinder monitoring pressure in the previous period, and taking the maximum value of the wheel cylinder monitoring pressure in preset monitoring time as the wheel cylinder pressure.
In a second aspect, an embodiment of the present invention further provides an EPB release compensation control apparatus, including:
a compensation amount determination module for determining a wheel cylinder pressure and determining an amount of compensation for EPB release according to the wheel cylinder pressure;
the total stroke determining module is used for determining the total stroke of EPB release according to the released compensation amount;
the speed determining module is used for acquiring a voltage value and a current value of a motor for driving the piston at the disk separation point and determining the release speed of the piston according to the voltage value and the current value;
the time calculation module is used for calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release;
and the compensation module is used for compensating the EPB release stroke according to the piston release time and the piston release speed.
In a third aspect, an embodiment of the present invention further provides a vehicle, which is integrated with the EPB release compensation control apparatus according to the second aspect.
The embodiment of the invention determines the compensation amount of EPB release by determining the wheel cylinder pressure and determining the compensation amount of EPB release according to the wheel cylinder pressure; determining the total stroke of EPB release according to the released compensation amount; acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point, and determining the release speed of the piston according to the voltage value and the current value; calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release; the EPB release stroke is compensated according to the piston release time and the piston release speed.
Therefore, the embodiment of the invention skillfully determines the compensation amount of EPB release according to the wheel cylinder pressure which can represent the brake pressure, and further can determine the total stroke of EPB release. In addition, in a parking release scene that a driver does not step on the brake pedal, the disc separation point means that the EPB is just released, and in the parking release scene that the driver steps on the brake pedal, due to the pushing effect of the brake oil pressure, when the EPB release time reaches the disc separation point, the friction plate and the brake disc are still in a contact state, the EPB is not completely released, and at this time, the piston needs to be continuously retracted by the amount of compensation to realize the complete release of the EPB. Based on the above, the embodiment of the invention determines the release speed of the piston according to the voltage and current values of the motor for driving the piston at the disk separation point, can further calculate the release time of the piston on the basis that the total stroke and the release speed of the piston are known, and can realize the compensation of the EPB release stroke through the motor for driving the piston. In conclusion, the embodiment of the invention can realize effective release of the EPB under large braking pressure, and is beneficial to relieving the dragging problem of the vehicle.
Drawings
FIG. 1 is a flow chart of an EPB release compensation control method according to an embodiment of the present invention;
FIG. 2 is a flow chart of another EPB release compensation control method according to an embodiment of the present invention;
FIG. 3 is a flow chart of yet another EPB release compensation control method provided by an embodiment of the present invention;
FIG. 4 is a flowchart of another EPB release compensation control method provided by an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an EPB release compensation control apparatus according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
In the process of releasing the parking brake of an actual vehicle, the inventor finds that when a driver steps on a brake pedal to release the parking brake, due to the randomness of the stepping pressure of the driver, the stepping pressures with different magnitudes can cause the EPB caliper piston to be further pushed to different positions by the brake oil pressure. Based on this, compare the parking release scene that the driver did not step on the brake pedal, the driver steps on the brake pedal hard and releases the parking, and the parking of big brake pressure release promptly can make brake disc and friction disc contact inseparabler. If the piston can retract and enable the brake disc and the friction plate to be restored to a state of just not contacting in a parking releasing scene that the brake pedal is not treaded, at the moment, if the piston displacement generated due to large brake pressure is not considered, when the parking is released, the piston still retracts by the same stroke as that in the parking releasing scene that the brake pedal is not treaded, the EPB cannot be released in place, the brake disc and the friction plate are difficult to restore to the non-contacting state, and the problems of vehicle dragging and the like are easily caused.
In view of the above, it is assumed that in a parking release scenario in which the brake pedal is not stepped on, the piston can retract and return the brake disc and the friction plate to a state just not in contact. Fig. 1 is a flowchart of an EPB release compensation control method according to an embodiment of the present invention, which is applicable to an EPB release compensation control scenario of any vehicle with an EPB system, such as a fuel vehicle, a hybrid vehicle, or an electric vehicle, but not limited to the EPB release compensation control apparatus according to an embodiment of the present invention, as an execution subject, and the execution subject may be implemented in software and/or hardware. As shown in fig. 1, the EPB release compensation control method specifically includes the steps of:
s110, determining wheel cylinder pressure, and determining the compensation amount released by the EPB according to the wheel cylinder pressure.
The wheel cylinder pressure refers to left and right rear wheel cylinder pressures, and the wheel cylinder pressures may be determined by measurement of a pressure sensor in an EFC or ABS pump in the vehicle.
The compensation amount of EPB release is a compensation stroke of EPB release corresponding to a displacement of the piston pushed by the brake oil pressure at a large brake pressure. It is understood that the brake pressure, i.e., the pressure at which the driver steps on the brake pedal, is proportional to the wheel cylinder pressure, and the greater the brake pressure, the greater the wheel cylinder pressure. Based on this, the present embodiment can determine the compensation amount for the EPB release from the wheel cylinder pressure that can characterize the magnitude of the brake pressure.
And S120, determining the total stroke of EPB release according to the released compensation amount.
Wherein the total stroke of the EPB release may include an amount of compensation for the EPB release. It can be known that the compensation amount released by the EPB is proportional to the total stroke released by the EPB, and the greater the compensation amount released by the EPB, the greater the total stroke released by the EPB.
S130, acquiring a voltage value and a current value of a motor for driving the piston at the disk separation point, and determining the piston release speed according to the voltage value and the current value.
Wherein, the disc is a brake disc and a friction plate.
The disk separation point is a point in time when the brake disk and the friction disk are just separated in a parking release scene in which the driver does not step on the brake pedal. Based on this, the voltage value and the current value of the motor that drives the piston at the disk separation point refer to the voltage value and the current value of the motor that drives the piston when the EPB release time reaches the disk separation point during the parking release process in which the driver steps on the brake pedal.
For example, the voltage value and the current value of the motor for driving the piston may be obtained by a hall sensor, and the piston release speed may be determined by obtaining the rotation speed of the motor for driving the piston according to the obtained voltage value and current value.
And S140, calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release.
The piston release time refers to the total time of the piston release, and is known to be the quotient of the total stroke of the EPB release and the piston release speed.
And S150, compensating the EPB release stroke according to the piston release time and the piston release speed.
The EPB release stroke compensation according to the piston release time and the piston release speed means that a motor for driving the piston is controlled according to a voltage value and/or a current value corresponding to the piston release speed in the piston release time, the motor drives the piston to retract adaptively, and the retraction stroke of the piston is the total stroke of EPB release, so that the EPB release stroke compensation is realized.
The embodiment of the invention determines the compensation amount of EPB release by determining the wheel cylinder pressure and determining the compensation amount of EPB release according to the wheel cylinder pressure; determining the total stroke of EPB release according to the released compensation amount; acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point, and determining the release speed of the piston according to the voltage value and the current value; calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release; the EPB release stroke is compensated according to the piston release time and the piston release speed.
Therefore, the embodiment of the invention skillfully determines the compensation amount of EPB release according to the wheel cylinder pressure which can represent the brake pressure, and further can determine the total stroke of EPB release. In addition, in a parking release scene that a driver does not tread a brake pedal, a disc separation point means that the EPB is just released, and in the parking release scene that the driver treads the brake pedal, due to the pushing action of the brake oil pressure, when the EPB release time reaches the disc separation point, a friction plate and a brake disc are still in a contact state, the EPB is not completely released, and at the moment, the piston needs to be continuously retracted by a compensation amount to realize the complete release of the EPB. Based on the above, the embodiment of the invention determines the piston release speed according to the voltage and current values of the motor for driving the piston at the disk separation point, can further calculate the piston release time on the basis of the known total stroke and the known piston release speed, and can realize the compensation of the EPB release stroke through the piston release time and the piston release speed by the motor for driving the piston. In conclusion, the embodiment of the invention can realize effective release of the EPB under large braking pressure, and is beneficial to relieving the dragging problem of the vehicle.
In addition to the above embodiments, the following description will be made of a specific method for determining the compensation amount of EPB release and the total stroke of EPB release, but the present invention is not limited thereto. Fig. 2 is a flowchart of another EPB release compensation control method according to an embodiment of the present invention, and as shown in fig. 2, the EPB release compensation control method specifically includes the following steps:
s210, determining the wheel cylinder pressure, and obtaining the compensation amount released by the EPB according to a table look-up of the wheel cylinder pressure.
The lookup table is a planar table formed by looking up the wheel cylinder pressure and the compensation amount released by the EPB. For example, the obtaining route of the plane table may be real vehicle calibration, or setting according to the existing vehicle data.
When the pressure of the brake pedal treaded by the driver is small, the wheel cylinder pressure is low, the pushing effect of the brake oil pressure on the piston is small, the influence on the effective release of the EPB is hardly generated, but the wheel cylinder pressure is continuously improved along with the gradual increase of the pressure of the brake pedal treaded by the driver, the pushing effect of the brake oil pressure on the piston tends to be obvious, and the effective release of the EPB is not facilitated. Based on this, optionally, when the wheel cylinder pressure is greater than the preset value, the greater the wheel cylinder pressure is, the greater the compensation amount corresponding to the wheel cylinder pressure is; when the wheel cylinder pressure is smaller than the preset value, the compensation amount corresponding to the wheel cylinder pressure is zero.
It can be understood that the preset value may be adaptively changed according to an actual application scenario of the EPB release compensation, which is not limited in the embodiment of the present invention. Illustratively, the table is a plane table formed by wheel cylinder pressure and compensation amount released by the EPB, according to the embodiment of the present invention, in the plane table, the unit of the wheel cylinder pressure is Bar, and the unit of the compensation amount released by the EPB is μm.
Watch 1
| Wheel cylinder pressure | Offset of EPB Release |
| 5 | 0 |
| 20 | 0 |
| 40 | 151 |
| 60 | 237 |
| 80 | 307 |
| 100 | 375 |
In this table, the preset value is 20Bar, see table one. When the wheel cylinder pressure is greater than 20Bar, the larger the wheel cylinder pressure is, the larger the compensation amount corresponding to the wheel cylinder pressure is; when the wheel cylinder pressure is less than or equal to 20Bar, the compensation amount corresponding to the wheel cylinder pressure is zero. It can be understood that when the wheel cylinder pressure is between 20Bar and 40Bar, the amount of compensation released by the EPB is between 0 μm and 151 μm; adaptively, when the wheel cylinder pressure is in other value intervals, the compensation amount released by the EPB can be changed correspondingly, and is not described in detail herein.
In addition, according to the embodiment, the compensation amount of EPB release obtained by looking up a table according to the wheel cylinder pressure is higher in precision, and the EPB can be effectively released under large brake pressure, so that the dragging problem of the vehicle can be relieved.
And S220, determining the total stroke of EPB release according to the compensation quantity, the reference quantity and the safety quantity.
Wherein the reference amount is a reference stroke of the EPB release when the wheel cylinder pressure is zero and the disc is just separated, and the safety amount is a safety stroke of the EPB release provided to prevent the disc from contacting when the wheel cylinder pressure is zero and the disc is just separated.
It is understood that the wheel cylinder pressure being zero indicates that the driver is not depressing the brake pedal, and the disk just separating indicates that the EPB release time is the disk separation point. Based on the above, the reference quantity is the total retraction stroke of the piston at the disk separation point under the condition that a driver does not tread a brake pedal; the safety amount is the safety margin for preventing the disc from contacting the retraction of the piston again due to the self-factor of the vehicle or the external environment factor when the disc is separated under the working condition that the driver does not tread the brake pedal, such as the self-vibration of the vehicle, the road bump and the like.
It can be understood that the reference quantity and the safety quantity may be adaptively changed according to an actual application scenario of the EPB release compensation, which is not limited by the embodiment of the present invention. Illustratively, the reference amount may be 1mm, and the safety amount may be 0.1mm to 0.15mm.
And S230, acquiring a voltage value and a current value of a motor for driving the piston at the disk separation point, and determining the piston release speed according to the voltage value and the current value.
And S240, calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release.
And S250, compensating the EPB release stroke according to the piston release time and the piston release speed.
In summary, according to the embodiment of the invention, the compensation quantity of high-precision EPB release can be obtained according to the table look-up of the wheel cylinder pressure, the effective EPB release under large brake pressure can be realized by setting the reference quantity and the safety quantity, the generation of the working condition of contact again after the separation of the discs caused by the vehicle factors or external environment factors can be prevented, and the dragging problem of the vehicle can be favorably relieved.
In addition to the above embodiments, a specific method for determining the piston release speed will be described below, but the present invention is not limited thereto. Fig. 3 is a flowchart of another EPB release compensation control method according to an embodiment of the present invention, and as shown in fig. 3, the EPB release compensation control method specifically includes the following steps:
s301, determining the wheel cylinder pressure, and obtaining the compensation amount released by the EPB according to a table look-up of the wheel cylinder pressure.
S302, determining the total stroke of EPB release according to the compensation quantity, the reference quantity and the safety quantity.
And S303, taking the current of the motor at the current moment as an original value of the current of the motor.
Wherein, the current time refers to each time in the EPB release process. It will be appreciated that during EPB release, the piston is driven by the motor to retract such that the friction pads are progressively further away from the brake disc; when the disks are not separated, the mutual extrusion of the disks can indirectly influence the operation of a motor rotor, and at the moment, the waveform of the motor current can generate a current peak; with the continuous reduction of the extrusion degree of the disk, the current waveform of the motor gradually tends to be stable. Therefore, in the embodiment, the motor current at each moment in the EPB releasing process needs to be determined, and the original value of the motor current at each moment is correspondingly determined.
S304, taking the preset duration as a period, and taking the average value of the motor current of the preset period number before the current moment as the motor current input value.
The preset duration and the preset cycle number may be adaptively adjusted according to the accuracy of the EPB release compensation and the actual working condition, which is not limited in the embodiment of the present invention. For example, the preset time duration may be 10ms, the preset number of cycles may be 10, and based on this, assuming that the current of the motor of the first 10 cycles at the present time is a1, a2, a3, a4, a5, a6, a7, a8, a9, and a10, respectively, and the motor current input value is A0, A0= (a 1+ a2+ a3+ a4+ a5+ a6+ a7+ a8+ a9+ a 10)/10. It will be appreciated that the preset number of motor currents may preferably be set to a preset number of motor currents immediately adjacent to and prior to the present time to improve the accuracy of the EPB release compensation.
And S305, acquiring the maximum value and the minimum value of the preset number of motor current input values before the current moment.
The preset number may also be adaptively adjusted according to the accuracy of EPB release compensation and the actual working condition, for example, the preset number may be 20. Likewise, the predetermined number of motor current input values may preferably be set to a predetermined number of motor current input values that are near and before the present time to improve the accuracy of the EPB release compensation.
And S306, taking the absolute value of the difference between the maximum value and the minimum value of the motor current input value as the fluctuation value of the motor current.
The fluctuation value of the motor current is used for representing the fluctuation condition of the motor current. In addition, the difference between the maximum value and the minimum value of the motor current input value may be the maximum value minus the minimum value, or may be the minimum value minus the maximum value, and if it is assumed that the maximum value of the motor current input value is A1, the minimum value of the motor current input value is A2, and the fluctuation value of the motor current is Δ a, Δ a = | A1-A2| = | A2-A1|.
S307, when the original value and the fluctuation value meet the preset condition, determining the disc separation, wherein the original value is the current value of the disc separation point.
The preset condition may be set according to an original value and a fluctuation value during the disc separation, and the determination method of the preset condition may be, but is not limited to, real vehicle calibration. In addition, determining the disc separation means determining that the EPB release time reaches the disc separation point.
In some embodiments, optionally, determining the disc separation when the original value and the fluctuation value satisfy a preset condition includes: when the original value is not greater than the first current preset value and the fluctuation value is not greater than the second current preset value, disk separation is confirmed.
Illustratively, the first current preset value may be 0.6A or 0.8A, the second current preset value may be 5A or 6A, and so on.
S308, acquiring a voltage value corresponding to the disk separation point.
Since the operating voltages corresponding to different vehicles are different, and the operating voltages of the vehicles may affect the voltage value corresponding to the disk separation point, the present embodiment may set the first current preset value in a segment manner according to the voltage value corresponding to the disk separation point, where the first current preset value may be set to 0.6A when the voltage value corresponding to the disk separation point is lower than 9V, and the first current preset value may be set to 0.8A when the voltage value corresponding to the disk separation point is higher than 9V.
Based on this, S308 may be performed in synchronization with S303. In some embodiments, if the voltage value corresponding to the disk separation point is lower than 9V, it is determined that the EPB release time reaches the disk separation point when the original value is not greater than 0.6A and the fluctuation value is not greater than 6A.
S309, calculating the first piston release speed according to the voltage value, calculating the second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
Here, it is understood that the unit of the first piston release rate is μm/ms/mV and the second piston release rate is μm/ms/mA.
It is understood that the voltage value corresponding to the disk separation point should theoretically correspond to the current value of the disk separation point. However, according to the internal structure of the existing vehicle, the voltage value and the current value are mostly measured separately by using two independent channels, and therefore, the voltage value and the current value measured under the actual working condition are often difficult to completely correspond to each other. Therefore, the larger value of the first piston release speed and the second piston release speed is used as the piston release speed, so that the time for releasing the piston can be effectively shortened, and the EPB release efficiency can be improved.
And S310, calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release.
And S311, compensating the EPB release stroke according to the piston release time and the piston release speed.
In summary, according to the embodiment of the invention, on the basis of realizing effective release of the EPB under a large braking pressure and relieving the vehicle dragging problem, the piston release speed is further determined by determining the motor voltage value at the disk separation point, the original value and the fluctuation value of the motor current, which is beneficial to shortening the piston release time and improving the EPB release efficiency.
In addition to the above embodiments, a specific determination method of the wheel cylinder pressure will be described below, but the present invention is not limited thereto. Fig. 4 is a flowchart of another EPB release compensation control method according to an embodiment of the present invention, and as shown in fig. 4, the EPB release compensation control method specifically includes the following steps:
s401, continuously judging whether the wheel cylinder monitoring pressure is credible or not within the preset monitoring time.
Wherein, the wheel cylinder monitoring pressure refers to the change situation of the wheel cylinder pressure in each period; whether the wheel cylinder monitoring pressure is credible or not means whether the wheel cylinder pressure exceeds or is lower than a certain limit value or not in the wheel cylinder pressure change process of each period; the preset monitoring time may be adaptively changed according to the accuracy requirement of the EPB release compensation, which is not limited in the embodiment of the present invention. For example, the preset monitoring time may be 0.5s, and when the preset time period is 10ms, the continuously determining whether the wheel cylinder monitoring pressure is credible within the preset monitoring time means that whether the change condition of the wheel cylinder pressure exceeds the limit value of the wheel cylinder pressure is determined every 10ms within 0.5 s.
It is understood that since the driver's effort on the brake pedal is random, a continuous judgment of the wheel cylinder monitoring pressure is required.
S402, continuously acquiring the maximum value of the cylinder monitoring pressure in the current period.
When the monitored pressure of the wheel cylinder is credible, the preset monitoring time is 0.5s, and the preset duration is 10ms, continuously acquiring the maximum value of the monitored pressure of the wheel cylinder in the current period means that the maximum value of the pressure of the wheel cylinder in the current 10ms is acquired every 10ms within 0.5 s.
S403, continuously comparing the maximum value of the wheel cylinder monitoring pressure with the wheel cylinder monitoring pressure in the previous period, taking the maximum value of the wheel cylinder monitoring pressure in the preset monitoring time as the wheel cylinder pressure, and obtaining the compensation quantity released by the EPB according to a table look-up of the wheel cylinder pressure.
The step of continuously comparing the maximum value of the wheel cylinder monitoring pressure with the wheel cylinder monitoring pressure of the previous period means that the maximum value of the wheel cylinder monitoring pressure of the current period is continuously compared with the wheel cylinder monitoring pressure of the previous period.
And S404, determining the total stroke of EPB release according to the compensation quantity, the reference quantity and the safety quantity.
And S405, taking the current of the motor at the current moment as an original value of the current of the motor.
S406, taking the preset duration as a period, and taking the average value of the motor current of the preset period number before the current moment as a motor current input value.
And S407, acquiring the maximum value and the minimum value of the preset number of motor current input values before the current moment.
And S408, taking the absolute value of the difference between the maximum value and the minimum value of the motor current input value as the fluctuation value of the motor current.
S409, when the original value and the fluctuation value meet the preset conditions, determining the disc separation, wherein the original value is the current value of the disc separation point.
S410, acquiring a voltage value corresponding to the disk separation point.
S411, calculating a first piston release speed according to the voltage value, calculating a second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
And S412, calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release.
And S413, compensating the EPB release stroke according to the piston release time and the piston release speed.
It is understood that the larger the wheel cylinder monitoring pressure is, the larger the pressure of the brake pedal stepped by the driver in the period is, the larger the wheel cylinder pressure is, the larger the displacement of the friction plate close to the brake disc by the motor-driven piston is, the closer the disc is contacted, and the larger the compensation amount released by the EPB is. Therefore, according to the embodiment of the invention, the maximum value of the wheel cylinder monitoring pressure is used as the wheel cylinder pressure, the total stroke retraction piston released by the EPB determined according to the compensation quantity released by the EPB can be ensured, the friction plate and the brake disc can be completely separated, the effective release of the EPB under the large braking pressure can be realized, and the dragging problem of the vehicle can be relieved.
Fig. 5 is a schematic structural diagram of an EPB release compensation control apparatus according to an embodiment of the present invention, which may be implemented by software and/or hardware. As shown in fig. 5, the EPB release compensation control apparatus provided by the present embodiment includes a compensation amount determining module 510, a total stroke determining module 520, a speed determining module 530, a time calculating module 540, and a compensation module 550.
A compensation amount determination module 510 for determining a wheel cylinder pressure and determining an amount of compensation for EPB release based on the wheel cylinder pressure; a total stroke determining module 520, configured to determine a total stroke released by the EPB according to the released compensation amount; a speed determining module 530, configured to obtain a voltage value and a current value of a motor for driving the piston at the disk separation point, and determine a piston release speed according to the voltage value and the current value; a time calculating module 540 for calculating the piston release time according to the piston release speed and the total stroke of the EPB release; and a compensation module 550 for compensating the EPB release stroke according to the piston release time and the piston release speed.
Alternatively, the compensation amount determination module 510 is used to obtain the compensation amount released by the EPB according to a look-up table of wheel cylinder pressures.
Optionally, when the wheel cylinder pressure is larger than the preset value, the larger the wheel cylinder pressure is, the larger the compensation amount corresponding to the wheel cylinder pressure is; when the wheel cylinder pressure is smaller than the preset value, the compensation amount corresponding to the wheel cylinder pressure is zero.
Optionally, the total stroke determining module 520 is specifically configured to determine the total stroke of the EPB release according to the compensation amount, the reference amount and the safety amount.
Wherein the reference amount is a reference stroke of the EPB release when the wheel cylinder pressure is zero and the disc is just separated, and the safety amount is a safety stroke of the EPB release set to prevent the disc from contacting when the wheel cylinder pressure is zero and the disc is just separated.
Optionally, the speed determining module 530 is specifically configured to obtain an original value and a fluctuating value of the motor current; when the original value and the fluctuation value meet the preset condition, determining the disc separation, wherein the original value is the current value of a disc separation point; acquiring a voltage value corresponding to a disk separation point; and calculating the first piston release speed according to the voltage value, calculating the second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
Optionally, the speed determining module 530 is further configured to confirm the disk separation when the original value is not greater than the first preset current value and the fluctuation value is not greater than the second preset current value.
Optionally, the speed determining module 530 is further configured to use the current of the motor at the current moment as an original value of the current of the motor; taking a preset duration as a period, and taking the average value of the motor current of the preset period number before the current moment as a motor current input value; acquiring the maximum value and the minimum value of the preset number of motor current input values before the current moment; and taking the absolute value of the difference value between the maximum value and the minimum value of the motor current input value as the fluctuation value of the motor current.
Optionally, the compensation amount determining module 510 is further configured to continuously determine whether the wheel cylinder monitoring pressure is reliable within a preset monitoring time; continuously acquiring the maximum value of the monitoring pressure of the inner cylinder in the current period; and continuously comparing the maximum value of the wheel cylinder monitoring pressure with the wheel cylinder monitoring pressure in the previous period, and taking the maximum value of the wheel cylinder monitoring pressure in the preset monitoring time as the wheel cylinder pressure.
The embodiment of the invention determines the wheel cylinder pressure through the compensation amount determining module, and determines the compensation amount released by the EPB according to the wheel cylinder pressure; determining the total stroke released by the EPB according to the released compensation amount through a total stroke determining module; acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point through a speed determination module, and determining the release speed of the piston according to the voltage value and the current value; calculating the release time of the piston by a time calculation module according to the release speed of the piston and the total stroke of EPB release; and compensating the EPB release stroke according to the piston release time and the piston release speed by a compensation module.
Therefore, the device skillfully determines the compensation amount of EPB release according to the wheel cylinder pressure capable of representing the brake pressure, and further can determine the total stroke of EPB release. In addition, in a parking release scene that a driver does not tread a brake pedal, a disc separation point means that the EPB is just released, and in the parking release scene that the driver treads the brake pedal, due to the pushing action of the brake oil pressure, when the EPB release time reaches the disc separation point, a friction plate and a brake disc are still in a contact state, the EPB is not completely released, and at the moment, the piston needs to be continuously retracted by a compensation amount to realize the complete release of the EPB. Based on the device, the device determines the release speed of the piston according to the voltage and current values of the motor for driving the piston at the disk separation point, can further calculate the release time of the piston on the basis that the total stroke and the release speed of the piston are known, and can realize the compensation of the EPB release stroke through the motor for driving the piston. In conclusion, the embodiment of the invention can realize effective release of the EPB under large braking pressure, and is beneficial to relieving the dragging problem of the vehicle.
The embodiment of the invention also provides a vehicle, which is integrated with the EPB release compensation control device provided by any embodiment of the invention, and the technical principle and the realization effect are similar and are not described again.
It is to be noted that the foregoing description is only exemplary of the invention and that the principles of the technology may be employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (9)
1. An EPB release compensation control method, comprising:
determining a wheel cylinder pressure, and determining a compensation amount for EPB release according to the wheel cylinder pressure;
determining the total stroke of EPB release according to the released compensation amount;
acquiring a voltage value and a current value of a motor for driving a piston at a disk separation point, and determining the release speed of the piston according to the voltage value and the current value;
calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release;
compensating an EPB release stroke according to the piston release time and the piston release speed;
the method for obtaining the voltage value and the current value of a motor for driving a piston at a disk separation point and determining the release speed of the piston according to the voltage value and the current value comprises the following steps:
acquiring an original value and a fluctuation value of the current of the motor;
when the original value and the fluctuation value meet a preset condition, determining the disc separation, wherein the original value is the current value of a disc separation point;
acquiring a voltage value corresponding to a disk separation point;
and calculating a first piston release speed according to the voltage value, calculating a second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
2. The method of claim 1, wherein determining the amount of compensation for EPB release based on the wheel cylinder pressure comprises:
and acquiring the compensation amount released by the EPB according to the wheel cylinder pressure lookup table.
3. The method according to claim 2, characterized in that, when the wheel cylinder pressure is larger than a preset value, the larger the wheel cylinder pressure is, the larger the compensation amount corresponding to the wheel cylinder pressure is; when the wheel cylinder pressure is smaller than the preset value, the compensation amount corresponding to the wheel cylinder pressure is zero.
4. The method of claim 1, wherein determining a total stroke of EPB release based on the amount of compensation released comprises:
determining the total stroke of EPB release according to the compensation quantity, the reference quantity and the safety quantity;
wherein the reference amount is a reference stroke of EPB release when the wheel cylinder pressure is zero and the disc just separates, and the safety amount is a safety stroke of EPB release provided to prevent the disc from contacting when the wheel cylinder pressure is zero and the disc just separates.
5. The method of claim 1, wherein determining the disc separation when the original value and the fluctuation value satisfy a preset condition comprises:
and confirming the separation of the disk when the initial value is not greater than a first current preset value and the fluctuation value is not greater than a second current preset value.
6. The method of claim 1, wherein obtaining the raw and fluctuating values of the motor current comprises:
taking the motor current at the current moment as an original value of the motor current;
taking a preset duration as a period, and taking the average value of the motor current of the preset period number before the current moment as a motor current input value;
acquiring the maximum value and the minimum value of the preset number of motor current input values before the current moment;
and taking the absolute value of the difference value between the maximum value and the minimum value of the motor current input value as the fluctuation value of the motor current.
7. The method according to claim 1, wherein determining a wheel cylinder pressure includes:
continuously judging whether the monitoring pressure of the wheel cylinder is credible or not within preset monitoring time;
continuously acquiring the maximum value of the wheel cylinder monitoring pressure in the current period;
and continuously comparing the maximum value of the wheel cylinder monitoring pressure with the wheel cylinder monitoring pressure in the previous period, and taking the maximum value of the wheel cylinder monitoring pressure in the preset monitoring time as the wheel cylinder pressure.
8. An EPB release compensation control apparatus, comprising:
a compensation amount determination module for determining a wheel cylinder pressure and determining an amount of compensation for EPB release according to the wheel cylinder pressure;
the total stroke determining module is used for determining the total stroke released by the EPB according to the released compensation amount;
the speed determining module is used for acquiring a voltage value and a current value of a motor for driving the piston at the disk separation point and determining the release speed of the piston according to the voltage value and the current value;
the time calculation module is used for calculating the release time of the piston according to the release speed of the piston and the total stroke of EPB release;
the compensation module is used for compensating the EPB release stroke according to the piston release time and the piston release speed;
the speed determination module is further used for acquiring an original value and a fluctuation value of the motor current; when the original value and the fluctuation value meet the preset condition, determining the disc separation, wherein the original value is the current value of the disc separation point; acquiring a voltage value corresponding to a disk separation point; and calculating the first piston release speed according to the voltage value, calculating the second piston release speed according to the current value, and taking the larger value of the first piston release speed and the second piston release speed as the piston release speed.
9. A vehicle characterized by being integrated with the EPB release compensation control apparatus according to claim 8.
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| JP5333114B2 (en) * | 2009-09-18 | 2013-11-06 | 株式会社アドヴィックス | Parking brake control device |
| JP2013071521A (en) * | 2011-09-27 | 2013-04-22 | Advics Co Ltd | Parking brake control apparatus |
| JP5737224B2 (en) * | 2012-05-28 | 2015-06-17 | 株式会社アドヴィックス | Brake device for vehicle |
| JP6575540B2 (en) * | 2017-02-03 | 2019-09-18 | マツダ株式会社 | Electric parking brake control device |
| KR20210011697A (en) * | 2019-07-23 | 2021-02-02 | 주식회사 만도 | Vehicle control apparatus and vehicle control method |
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