KR102454407B1 - Method and system of braking pressure estimation of automobile pneumatic brake - Google Patents

Abstract

), 노말 오픈 밸브의 명령(

) 및 노말 클로즈 밸브의 명령(

)을 입력값으로 입력 받는 단계 및 상기 입력값과 하기의 [수학식 1]을 이용하여 현재 휠 실린더의 압력(

)을 추정하는 단계를 포함할 수 있다.
[수학식 1]

(이때,

는 현재 휠 실린더 압력,

은 이전 휠 실린더 압력,

공기압축탱크 내부 압력,

는 샘플링 시간,

는 노말 오픈 밸브의 명령,

는 노말 클로즈 밸브의 명령,

는 실험상수이다.)The present invention relates to a method and system for estimating the braking pressure of a pneumatic brake of an automobile, and more particularly, to a method and system for estimating the pressure of a current wheel cylinder from the pressure of an air compression tank, commands of a normally open valve and a normally closed valve. it's about
In the method for estimating the braking pressure of a pneumatic brake of a vehicle according to an embodiment of the present invention, the pressure in the air compression tank (

), command of normal open valve (

) and the command of the normally closed valve (

) as an input value and using the input value and the following [Equation 1], the pressure of the current wheel cylinder (

) may include the step of estimating.
[Equation 1]

(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

pressure inside the air compression tank,

is the sampling time,

is the command of the normally open valve,

is the command of the normally closed valve,

is the experimental constant.)

Description

TECHNICAL FIELD [0002] Method and system of braking pressure estimation of automobile pneumatic brake

The present invention relates to a method and system for estimating the braking pressure of a pneumatic brake of an automobile, and more particularly, to a method and system for estimating the pressure of a current wheel cylinder from the pressure of an air compression tank, commands of a normally open valve and a normally closed valve. it's about

Recently, development of a hybrid vehicle, a fuel cell vehicle, an electric vehicle, etc. has been completed or is in progress in order to improve fuel efficiency and reduce exhaust gas. A braking device, that is, a brake is necessarily installed in such a vehicle.

A vehicle brake is a device that reduces the speed of a moving vehicle or stops the vehicle. Brakes are closely related not only to the braking of the vehicle, but also to the direction control of the vehicle.

A vehicle brake is a mechanical brake that transmits the force of the hand applied to the pedal to the wheels using a mechanical device, a hydraulic brake using the point that the force applied to a part of the liquid is transmitted in all directions with the same strength, or the engine operates the air compressor It is divided into pneumatic brakes that generate braking action by pushing the brake shoe to the drum using compressed air generated from the compressor.

In particular, in the pneumatic brake that controls the movement of a vehicle by applying compressed air to the wheels, it is necessary to accurately control the pressure of individual wheels in stabilizing the vehicle control. this is being requested

As a prior art, Korean Patent Laid-Open Publication No. 10-2015-0086968 discloses a method of estimating a master cylinder pressure signal in a hydraulic brake.

KR 10-2015-0086968 A

An object of the present invention is to provide a method capable of accurately estimating the pressure of a wheel cylinder with only given information without having a pressure sensor on the wheel cylinder of a pneumatic brake in accordance with the above-mentioned development requirements.

As an embodiment of the present invention, a method for estimating the braking pressure of a pneumatic brake of an automobile is provided.

), 노말 오픈 밸브의 명령(

) 및 노말 클로즈 밸브의 명령(

)을 입력값으로 입력 받는 단계 및 상기 입력값과 하기의 [수학식 1]을 이용하여 현재 휠 실린더의 압력(

)을 추정하는 단계를 포함할 수 있다.In the method for estimating the braking pressure of a pneumatic brake of a vehicle according to an embodiment of the present invention, the pressure in the air compression tank (

), command of normal open valve (

) and the command of the normally closed valve (

) as an input value and using the input value and the following [Equation 1], the pressure of the current wheel cylinder (

) may include the step of estimating.

[Equation 1]

는 현재 휠 실린더 압력,

은 이전 휠 실린더 압력,

공기압축탱크 내부 압력,

는 샘플링 시간,

는 노말 오픈 밸브의 명령,

는 노말 클로즈 밸브의 명령,

는 실험상수이다.)(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

pressure inside the air compression tank,

is the sampling time,

is the command of the normally open valve,

is the command of the normally closed valve,

is the experimental constant.)

)에서 이전 휠 실린더 압력(

)을 뺀 값이 공기압축탱크 내부의 압력(

)을 2로 나눈값 이상인 경우와 미만인 경우가 서로 상이한 것을 특징으로 할 수 있다.In the method for estimating the braking pressure of a pneumatic brake of a vehicle according to an embodiment of the present invention, in [Equation 1], k1 is the pressure inside the air compression tank (

) from the previous wheel cylinder pressure (

) minus the pressure inside the air compression tank (

) divided by 2 may be characterized as being different from each other if it is greater than or equal to the value divided by 2.

As an embodiment of the present invention, a computer-readable recording medium in which a program for implementing the above-described method is recorded is provided.

As an embodiment of the present invention, a system for estimating the braking pressure of a pneumatic brake of an automobile is provided.

), 노말 오픈 밸브의 명령(

), 노말 클로즈 밸브의 명령(

) 및 [수학식 1]을 통해 휠 실린더의 압력을 추정하는 것을 특징으로 할 수 있다.According to an embodiment of the present invention, a system for estimating braking pressure of a pneumatic brake of a vehicle includes a pedal receiving a braking command from a driver, a control unit receiving a braking command from the pedal and controlling an operation of a normally open valve or a normally closed valve; and a brake provided with a wheel cylinder or an air compression tank connected to the atmosphere through the normally open valve or the normally closed valve, and the wheel cylinder receiving air from the air compression tank and applying a frictional force to the wheels, the control unit comprising: The pressure inside the air compression tank (

), command of normal open valve (

), command of the normally closed valve (

) and [Equation 1] may be characterized by estimating the pressure of the wheel cylinder.

[Equation 1]

는 현재 휠 실린더 압력,

은 이전 휠 실린더 압력,

공기압축탱크 내부 압력,

는 샘플링 시간,

는 노말 오픈 밸브의 명령,

는 노말 클로즈 밸브의 명령,

는 실험상수이다.)(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

pressure inside the air compression tank,

is the sampling time,

is the command of the normally open valve,

is the command of the normally closed valve,

is the experimental constant.)

)에서 이전 휠 실린더 압력(

)을 뺀 값이 공기압축탱크 내부의 압력(

)을 2로 나눈값 이상인 경우와 미만인 경우가 서로 상이한 것을 특징으로 할 수 있다.In the system for estimating the braking pressure of a pneumatic brake of a vehicle according to an embodiment of the present invention, in [Equation 1], k1 is the pressure inside the air compression tank (

) from the previous wheel cylinder pressure (

) minus the pressure inside the air compression tank (

) divided by 2 may be characterized as being different from each other if it is greater than or equal to the value divided by 2.

According to the present invention, there is an advantage that the pressure of the wheel cylinder of the pneumatic brake can be accurately estimated without having a pressure sensor in the wheel cylinder.

The effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be.

1 is a block diagram of a system for estimating a braking pressure of a pneumatic brake according to the present invention.
2 is an overall configuration diagram of a braking pressure estimation system of a pneumatic brake according to the present invention.
3 shows the braking process of the pneumatic brake according to the present invention.
4 is a flowchart of a method for estimating a braking pressure of a pneumatic brake according to the present invention.
5 is an algorithm of a method for estimating a braking pressure of a pneumatic brake according to the present invention.
6 is a first experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.
7 is a second experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.
8 is a third experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

In the entire specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, terms such as "unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. In addition, throughout the specification, when a part is "connected" with another part, this includes not only the case of "directly connected" but also the case of "connecting with another element in the middle".

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a system for estimating a braking pressure of a pneumatic brake according to the present invention, and FIG. 2 is an overall configuration diagram of a system for estimating a braking pressure of a pneumatic brake according to the present invention.

), 노말 오픈 밸브(410)의 명령(

), 노말 클로즈 밸브(420)의 명령(

) 및 [수학식 1]을 통해 휠 실린더의 압력을 추정하는 것을 특징으로 할 수 있다.1 and 2 , in the system for estimating the braking pressure of the pneumatic brake 400 of a vehicle according to an embodiment of the present invention, the pedal 100 receives a braking command from the driver, and the braking command from the pedal 100 The control unit 200 for controlling the operation of the normal open valve 410 (Normal Open Valve: NO valve 410) or the normal close valve 420 (Normal Close Valve: NC valve 420) by receiving An air compression tank 300 connected to a wheel cylinder or the atmosphere through an open valve 410 or the normally closed valve 420, and the wheel cylinder receiving air from the air compression tank 300 and applying a frictional force to the wheels are provided. and a brake 400 , the control unit 200 controls the pressure inside the air compression tank 300 (

), the command of the normal open valve 410 (

), the command of the normally close valve 420 (

) and [Equation 1] may be characterized by estimating the pressure of the wheel cylinder.

[Equation 1]

는 현재 휠 실린더 압력,

은 이전 휠 실린더 압력,

공기압축탱크(300) 내부 압력,

는 샘플링 시간,

는 노말 오픈 밸브(410)의 명령,

는 노말 클로즈 밸브(420)의 명령,

는 실험상수이다.)(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

The internal pressure of the air compression tank 300,

is the sampling time,

is the command of the normal open valve 410,

is the command of the normally close valve 420,

is the experimental constant.)

The pedal 100 may receive a brake command input by the driver's foot or hand, and may transmit the received command to the air compression tank 300 , the NO or NC valve 420 , and the like.

The NO valve 410 is in a state in which the inlet of the fluid is opened in a normal state of de-energization, and the NC valve 420 is in a state in which the inlet of the fluid is blocked in a normal state of de-energization.

That is, the NO valve 410 opens the flow path when it is off, and closes the flow path when it is on. Conversely, the NC valve 420 closes the flow path when it is off, and opens the flow path when it is on.

The normally open valve 410 connects the air compression tank 300 to the wheel cylinder provided inside the brake 400 of the vehicle, and the normally close valve 420 connects the air compression tank 300 to the atmosphere. .

The air compression tank 300 stores compressed air, and may supply compressed air to the brake 400 to stop a running vehicle or control the direction of the vehicle.

The brake 400 may be mounted on each wheel of the vehicle, and may be divided into two of the front wheel brake 400 or the rear wheel brake 400 , and each wheel may be individually controlled, or divided into front and rear. it could be

The control unit 200 receives the internal pressure of the air compression tank 300 and the commands of the NO valve and the NC valve 420 as input values, and can estimate the current pressure of the wheel cylinder by substituting it into [Equation 1]. have.

)에서 이전 휠 실린더 압력(

)을 뺀 값이 공기압축탱크(300) 내부의 압력(

)을 2로 나눈값 이상인 경우와 미만인 경우가 서로 상이한 것을 특징으로 할 수 있다.In the [Equation 1], k1 is the pressure inside the air compression tank 300 (

) from the previous wheel cylinder pressure (

) is the pressure inside the air compression tank 300 (

) divided by 2 may be characterized as being different from each other if it is greater than or equal to the value divided by 2.

[Equation 1] will be described in detail with reference to FIG. 5 below.

3 shows the braking process of the pneumatic brake according to the present invention.

Referring to FIG. 3 , when both the NO valve 410 and the NC valve 420 are off, the NO valve 410 opens and the NC valve 420 closes, so the brake 400 in the air compression tank 300 is closed. The air is introduced into the furnace and becomes a pressurized state to apply pressure to the brake 400 .

Conversely, when both the NO valve 410 and the NC valve 420 are in an on state, the NO valve 410 is closed and the NC valve 420 is opened, so that the air of the brake 400 is discharged to atmospheric pressure. . In addition, when the NO valve 410 is on, and the NC valve 420 is in the off state, the NO valve 410 and the NC valve 420 are both closed, so the air flow is all kept in a blocked state. .

4 is a flowchart of a method for estimating a braking pressure of a pneumatic brake according to the present invention.

), 노말 오픈 밸브(410)의 명령(

) 및 노말 클로즈 밸브(420)의 명령(

)을 입력값으로 입력 받는 단계 및 상기 입력값과 하기의 [수학식 1]을 이용하여 현재 휠 실린더의 압력(

)을 추정하는 단계를 포함할 수 있다.Referring to FIG. 4 , in the method for estimating the braking pressure of the pneumatic brake 400 of a vehicle according to an embodiment of the present invention, the pressure inside the air compression tank 300 (

), the command of the normal open valve 410 (

) and the command of the normally close valve 420 (

) as an input value and using the input value and the following [Equation 1], the pressure of the current wheel cylinder (

) may include the step of estimating.

는 현재 휠 실린더 압력,

은 이전 휠 실린더 압력,

공기압축탱크(300) 내부 압력,

는 샘플링 시간,

는 노말 오픈 밸브(410)의 명령,

는 노말 클로즈 밸브(420)의 명령,

는 실험상수이다.)(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

The internal pressure of the air compression tank 300,

is the sampling time,

is the command of the normal open valve 410,

is the command of the normally close valve 420,

is the experimental constant.)

That is, according to the present invention, it is possible to estimate the pressure inside the wheel cylinder through the pressure inside the air compression tank 300 and the command values of the NO valve 410 and the NC valve 420, so that each wheel cylinder has a pressure sensor. Costs can be reduced by doing so.

5 is an algorithm of a method for estimating a braking pressure of a pneumatic brake according to the present invention.

Referring to FIG. 5 , the structure of [Equation 1] can be seen.

The derivation process of [Equation 1] is as follows.

이고 속도가

이고, 공기압축탱크(300)에서 배출된 공기의 압력이 P, 이동 속도가

인 경우 [수학식 2]와 같은 수식이 성립된다.According to Bernoulli's equation, the pressure of the air in the air compression tank 300 is

and the speed

, the pressure of the air discharged from the air compression tank 300 is P, and the movement speed is

In the case of , the same formula as [Equation 2] is established.

At this time. The pressure P of the air discharged from the air compression tank 300 is equal to the pressure applied to the wheel cylinder.

이므로,

이다.At this time,

Because of,

to be.

)을 수식으로 나타내면 아래의 [수학식 3]과 같다.Also, the flow rate representing the mass of material passing per unit time (

) is expressed as a formula, as in [Equation 3] below.

는 부피의 미분값,

는 단면적,

는 공기압축탱크(300)에서 배출된 공기의 이동 속도이다.)(here,

is the derivative of the volume,

is the cross-sectional area,

is the movement speed of the air discharged from the air compression tank 300.)

When [Equation 2] is substituted into [Equation 3], it is as follows.

In this case, the experimental relationship between pressure and volume is as follows.

Differentiating both sides of [Equation 5] is as follows.

Substituting [Equation 4] into [Equation 6] above, it is as follows.

Since the cross-sectional area A of the flow path can be calculated by on/off of the NO valve 410 and the NC valve 420, [Equation 7] can be expressed as follows.

는 밸브의 명령을 나타냄.)(here,

indicates the command of the valve.)

In [Equation 8], the relationship between the pressure of the wheel cylinder in the pressurized state and the NO valve 410 and the NC valve 420 is expressed in discrete time as follows.

In addition, since the pressure inside the air compression tank 300 is the same as the external atmospheric pressure in the reduced pressure state, the following equation is established.

는

이다.In the pressurized state, both the NO valve 410 and the NC valve 420 are off, the NO valve 410 is off when the command is 1, and the NC valve 420 is off when the command is 0, so the [ of Equation 9]

Is

to be.

는

이다.Conversely, in the reduced pressure state, both the NO valve 410 and the NC valve 420 are on, the NO valve 410 is on when the command is 0, and the NC valve 420 is on when the command is 1, of [Equation 10] above

Is

to be.

Since [Equation 1] according to the present invention considers both the pressurized state and the reduced pressure state, [Equation 9] and [Equation 10] are combined.

)에서 이전 휠 실린더 압력(

)을 뺀 값이 공기압축탱크(300) 내부의 압력(

)을 2로 나눈값 이상인 경우와 미만인 경우에 따라 실험상수(

)의 값이 상이한 것을 알 수 있다.5, the pressure inside the air compression tank 300 in a pressurized state (

) from the previous wheel cylinder pressure (

) is the pressure inside the air compression tank 300 (

) divided by 2 for more than and less than the experimental constant (

), it can be seen that the values are different.

)에서 이전 휠 실린더 압력(

)을 뺀 값이 클 때는 공기의 속도가 크나 공기압축탱크(300) 내부의 압력(

)에서 이전 휠 실린더 압력(

)을 뺀 값이 작을 때는 공기의 속도가 느리기 때문이다.This is supplied while compressing the spring when air is supplied to the wheel cylinder, so the pressure inside the air compression tank 300 (

) from the previous wheel cylinder pressure (

) is large, the speed of the air is large, but the pressure (

) from the previous wheel cylinder pressure (

) is small because the speed of air is slow.

The solid line in FIG. 5 represents the first process of repeatedly estimating the pressure of the current wheel cylinder,

)을 이전 휠 실린더의 압력(

)에 대입하여 다시 현재 휠 실린더의 압력(

)을 추정함으로써, 시간에 따른 휠 실린더 압력(

)을 실시간으로 추정할 수 있을 것이다.5, the pressure of the current wheel cylinder estimated by the present invention (

) to the pressure of the previous wheel cylinder (

) to the current wheel cylinder pressure (

) by estimating the wheel cylinder pressure over time (

) can be estimated in real time.

6 is a first experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.

Referring to FIG. 6 , it can be seen that the pressure applied to the brake 400 increases when both the NO valve 410 and the NC valve 420 are off, and the NO valve 410 and the NC valve 420 are both off. When it is on, it can be seen that the pressure applied to the brake 400 is reduced.

6A shows the pressure estimated by the present invention, and FIG. 6B shows the pressure measured by the pressure sensor.

In the case of FIG. 6, the maximum error rate was 1.523 bar, the minimum error rate was -0.750 bar, the average error rate was 0.075 bar, and the RMS error rate was 0.336 bar, and it can be seen that the accuracy of the pressure estimation method according to the present invention is very high. .

7 is a second experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.

7 shows that the accuracy of the pressure estimation method was tested when the speed of on/off operation control of the NO valve 410 and the NC valve 420 was slowed.

7, the maximum error rate was 1.108 bar, the minimum error rate was -1.311 bar, the average error rate was 0.024 bar, and the RMS error rate was 0.161 bar, and it can be seen that the accuracy of the pressure estimation method according to the present invention is very high. .

8 is a third experimental example of a method for estimating a pneumatic brake braking pressure according to the present invention.

8 shows that the accuracy of the pressure estimation method was tested when the speed of controlling the on/off operation of the NO valve 410 and the NC valve 420 was very fast.

In the case of Figure 8, the maximum error rate is 2.236 bar, the minimum error rate is -0.894 bar, the average error rate is 0.199 bar, and the RMS error rate is 0.452 bar, and although the maximum error rate is the largest, the accuracy of the pressure estimation method according to the present invention is still very You can see the high

The foregoing description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention. do.

100: pedal
200: control unit
300: air compression tank
400: brake
410: normally open valve, NO valve
420: normally close valve, NC valve

Claims (5)

The pressure inside the air compression tank (

), command of normal open valve (

) and the command of the normally closed valve (

) as an input value; and
Using the above input value and the following [Equation 1], the pressure of the current wheel cylinder (

), a method for estimating the braking pressure of a pneumatic brake of an automobile comprising the step of estimating.
[Equation 1]

(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

pressure inside the air compression tank,

is the sampling time,

is the command of the normal open valve,

is the command of the normally closed valve,

is the experimental constant.)
The method of claim 1,
In [Equation 1], k1 is,
The pressure inside the air compression tank (

) from the previous wheel cylinder pressure (

) minus the pressure inside the air compression tank (

) divided by 2 is different from the case where it is equal to or greater than the value divided by 2.
A computer-readable recording medium in which a program for implementing the method of any one of claims 1 or 2 is recorded.
a pedal receiving a braking command from the driver;
a control unit configured to receive a braking command from the pedal and control an operation of a normally open valve or a normally close valve;
an air compression tank connected to a wheel cylinder or atmosphere through the normally open valve or the normally closed valve; and
and a brake provided with the wheel cylinder that receives air from the air compression tank and applies friction to the wheel,
The control unit, the pressure inside the air compression tank (

), command of normal open valve (

), the command of the normally closed valve (

) and [Equation 1] for estimating the pressure of the wheel cylinders, the braking pressure estimation system of the pneumatic brake of a car.
[Equation 1]

(At this time,

is the current wheel cylinder pressure,

is the previous wheel cylinder pressure,

pressure inside the air compression tank,

is the sampling time,

is the command of the normal open valve,

is the command of the normally closed valve,

is the experimental constant.)
5. The method of claim 4,
In [Equation 1], k1 is,
The pressure inside the air compression tank (

) from the previous wheel cylinder pressure (

) minus the pressure inside the air compression tank (

Brake pressure estimation system for automobile pneumatic brake, characterized in that the case where ) divided by 2 is different from the case where it is equal to or greater than the value divided by 2

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