JP2002145044A - Brake booster pressure estimating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake booster pressure estimating device capable of estimating the pressure of a brake booster at a low cost and with precision. SOLUTION: This device for estimating a pressure in the brake booster 13 encouraging operation of a brake pedal 2 by using a negative pressure in an engine 6 comprises a stroke sensor 3 for detecting a stroke amount of the brake pedal 2; a memory 18 for storing data on relationship between the stroke amount of the brake pedal 2 and a pressure change amount of the brake booster 13; and an electronic control unit 1 for determining the pressure change amount of the brake booster 13 from the stroke amount of the brake pedal 2 detected by the stroke sensor 3, based on the data stored in the memory 18 and for calculating a pressure estimated amount of the brake booster 13, based on the obtained pressure change amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pressure estimating apparatus for estimating a pressure of a brake booster in a vehicle.

[0002]

2. Description of the Related Art In a vehicle, in a brake booster for braking the vehicle by utilizing the negative pressure of the engine, when the negative pressure of the engine decreases, the pressure of the brake booster increases and the effectiveness of the brake decreases. Therefore, conventionally, the pressure of the brake booster is detected, and if the detected output exceeds a predetermined value, for example, the compressor of the air conditioner is temporarily stopped to recover the negative pressure of the engine and reduce the pressure of the brake booster. This improves the effectiveness of the brake.

[0003] In a direct injection engine or the like, combustion is performed with the throttle valve opened, that is, lean combustion is performed. When the lean combustion is performed, the engine negative pressure usually decreases, and the pressure of the brake booster decreases. Get higher. Therefore, in this case as well, the pressure of the brake booster is detected, and if the detection output exceeds a predetermined value, lean combustion is switched to normal combustion to recover the negative pressure of the engine, and the pressure of the brake booster is reduced. By lowering, the effectiveness of the brake is improved.

In order to properly control the air conditioner and the internal combustion engine as described above, it is necessary to accurately detect the pressure of the brake booster. For example, JP-A-10-1754
No. 63 discloses that a pressure sensor is provided in a pipe branching from an intake pipe and reaching a brake booster, and the pressure of the brake booster is detected by the pressure sensor. The publication also discloses a method of calculating the deceleration of the vehicle from the vehicle speed, the state of the brake switch, the degree of the gradient, and the like, and estimating the pressure of the brake booster by taking into account the deceleration by the engine brake as necessary. It has been disclosed.

[0005]

However, such a pressure sensor is generally expensive and causes an increase in component costs. Further, in the method of estimating the pressure of the brake booster, the pressure is estimated based on various factors such as the vehicle speed, so that the control is complicated. Usually, it is difficult to derive a qualitative relationship with the pressure of the brake booster from the deceleration of the vehicle, and it is difficult to estimate an accurate value.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been conceived under the above circumstances, and provides a brake booster pressure estimating apparatus capable of accurately estimating the pressure of a brake booster at low cost. Is the task.

In order to solve the above problems, the present invention takes the following technical measures.

A pressure estimating device for a brake booster provided by the present invention is a pressure estimating device for a brake booster which assists the operation of a brake pedal by utilizing a negative pressure of an engine, and detects an operation equivalent amount of the brake pedal. And a storage unit for storing the relationship between the amount of operation of the brake pedal and the amount of pressure change of the brake booster as data, and the operation of the brake pedal detected by the sensor based on the data stored in the storage unit. Determining means for determining a pressure change amount of the brake booster from the amount, and calculating means for calculating an estimated pressure amount of the brake booster based on the pressure change amount determined by the determining means. .

According to the above arrangement, the sensor detects the amount of operation of the brake pedal, for example, the amount of change in stroke of the brake pedal, and determines the amount of change in pressure of the brake booster based on the detected amount of change in stroke. Here, the relationship between the amount of change in stroke of the brake pedal and the amount of change in pressure of the brake booster is determined in advance by a vehicle running test or the like and stored in a memory or the like, so that the amount of change in pressure of the brake booster can be easily determined. Can be Then, for example, the estimated pressure value of the brake booster at that time is calculated from the amount of change in the pressure of the brake booster, for example, by adding it to the estimated pressure value of the immediately preceding brake booster. As described above, according to the above control, the estimated pressure value of the brake booster can be easily obtained, and an expensive pressure sensor as in the conventional configuration is not required, so that the cost can be reduced.

According to a preferred embodiment of the present invention,
The sensor detects the stroke amount of the brake pedal. As described above, if the stroke sensor of the brake pedal is used to detect the amount of operation of the brake pedal, the stroke sensor can be used for other controls such as ABS control and skid control. Therefore, the versatility of the device can be improved.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is an explanatory view showing one example of a pressure estimating device for a brake booster according to the present invention. This pressure estimating device includes an electronic control unit 1 mounted on a vehicle.
And a stroke sensor 3 for detecting a stroke amount when the brake pedal 2 is depressed. Hereinafter, this pressure control device is
This will be described in detail, including the configuration around it.

As shown in FIG. 1, an engine 6 has an intake pipe 8 through which air sucked from an air cleaner (not shown) flows.
A throttle valve 9 for adjusting the amount of intake air in the intake pipe 8 is provided in the middle of the intake pipe 8. The intake pipe 8 near the engine 6 is provided with a pressure sensor 10 for detecting the pressure of the intake pipe 8.
This pressure sensor 10 is used for engine control such as ignition timing control and fuel injection control.

A pipe 12 is branched and connected to the intake pipe 8, and a brake booster 13 is connected to a tip of the pipe 12. A check valve 14 is provided in the middle of the pipe 12 as a check valve that allows only one-way flow of the fluid. By the action of the check valve 14, a negative pressure of the intake pipe 8 acts on the brake booster 13 via the pipe line 12, and the brake booster 13 operates the brake pedal 2 according to a difference between the negative pressure and the atmospheric pressure. Amplify the treading power of

The brake pedal 2 is connected to the brake booster 13 via a push rod 16 on the vehicle compartment side. A stroke sensor 3 for detecting a stroke when the brake pedal 2 is depressed;
A brake switch 17 that is turned on when the brake pedal 2 is operated is attached.

The stroke sensor 3 detects the stroke amount of the brake pedal 2 based on the rotation angle of the rotating shaft 2a when the brake pedal 2 is depressed, for example. The configuration is not particularly limited.

An electronic control unit 1 (hereinafter referred to as "ECU 1")
) Controls the operation of the engine 6.
It has a memory 18 such as a ROM, a RAM or an EEPROM. In addition to the engine operation control program, the memory 18 stores an estimated value of the pressure of the brake booster 13, a conversion table for converting an amount of depression of the brake pedal 2 by a rider into a pressure change amount of the brake booster 13, and the like. Have been.

Normally, when the brake pedal 2 is depressed, the pressure of the brake booster 13 increases. However, the above conversion table shows the pressure change amount of the brake booster 13 according to the value of the depression amount (stroke amount) of the brake pedal 2. (Pressure increase) is stored. The value stored in the conversion table is a value obtained in advance by a traveling test of the vehicle. Note that the memory 18 may store a function formula or the like representing the relationship between the depression amount of the brake pedal 2 and the pressure change amount of the brake booster 13 instead of the conversion table.

The ECU 1 includes the pressure sensor 10 described above,
The stroke sensor 3 and the brake switch 17 are connected. The ECU 1 is also connected to devices and switches other than the above-described sensors and the like.
A predetermined process in the operation control is performed based on the operation control program stored in 8 and detection signals sent from each sensor and each switch.

Next, the operation control in the ECU 1 will be described.
This will be described with reference to the flowchart shown in FIG. In addition,
In this description, a timing chart showing the estimated value of the pressure of the brake booster in FIG. 3 is appropriately referred to. Also,
The routine shown in the flowchart of FIG.
It is repeatedly performed at a cycle of ８8 μsec.

First, when the ignition switch is turned on by the occupant to start driving, the ECU 1 inputs a detection signal output from the pressure sensor 10 of the intake pipe 8 (step S1), and the pressure of the intake pipe 8 is increased. Recognize. Next, it is determined whether or not the pressure in the intake pipe 8 is smaller than the estimated pressure value of the brake booster 13 (step S2).
At the start of the operation, a predetermined initial value is substituted for the estimated pressure value, and the determination is performed. The initial value is set to an arbitrary value and is stored in the memory 18 in advance.

When the ECU 1 determines that the estimated pressure value (or the initial value) of the brake booster 13 is larger than the pressure of the intake pipe 8 (step S2: YES), the ECU 1 uses the actually measured value detected by the pressure sensor 10. The pressure of a certain intake pipe 8 is set as an estimated pressure value of the brake booster 13 (step S
3). For example, in FIG. 3, when the initial value is the pressure value a, the pressure value is changed to the pressure value b of the intake pipe 8. If the initial value is smaller than the pressure of the intake pipe 8 in step S2, the process proceeds to step S4.

Next, the ECU 1 operates the brake switch 1
It is determined whether or not the brake pedal 2 has been turned on, in other words, whether or not the rider has depressed the brake pedal 2 (step S4). If the brake switch 17 is off, the ECU
1 determines that the brake pedal 2 has not been depressed (step S4: NO), and returns to step S1.

As described above, during the period before the brake pedal 2 is depressed (see period A in FIG. 3), when the accelerator pedal is depressed by the rider and the vehicle speed increases, the engine negative pressure increases and the intake pipe 8 is closed. The pressure decreases, and accordingly, the pressure of the brake booster 13 also decreases.
Therefore, in this period A, the brake booster 1
3 is controlled so as to be equal to the pressure of the intake pipe 8.

On the other hand, if the brake pedal 2 is depressed by the rider and the brake switch 17 is turned on, E
The CU 1 determines that the brake pedal 2 has been depressed (Step S4: YES). Next, the ECU 1 detects the output of the stroke sensor 3 (Step S5), and recognizes the stroke change amount when the brake pedal 2 is depressed by the rider.

Next, in step S6, the ECU 1 reads the pressure change amount of the brake booster 13 corresponding to the stroke change amount from the conversion table stored in the memory 18 and temporarily stores the pressure change amount in the memory 18. To memorize. In this case, when the brake pedal 2 is depressed, the pressure of the brake booster 13 increases. However, as described above, the pressure change amount of the brake booster 13 with respect to the stroke change amount of the brake pedal 2 is obtained in advance by a driving experiment or the like. Since the value is used, the value is highly accurate.

In step S6 of FIG. 2, the relationship between the amount of change in stroke of the brake pedal 2 and the amount of change in pressure of the brake booster 13 is shown as a proportional relationship. The present invention is not limited to this, and may be a functional relationship or another relationship.

Next, the ECU 1 adds the pressure change amount of the brake booster 13 read from the conversion table and stored in the memory 18 to the previous estimated value of the pressure of the brake booster 13, and adds the added value to the current value. Is updated as an estimated pressure value of the brake booster 13 and stored in the memory 18. Here, the previous estimated value of the pressure of the brake booster 13 refers to the estimated value of the pressure of the brake booster 13 obtained in the previous routine.

As described above, the previous brake booster 13
Of the pressure change of the brake pedal 2 from the previous time to the current time
By adding the pressure change amount of 3, the current estimated pressure value of the brake booster 13 is obtained. And
The estimated pressure value of the brake booster 13 thus obtained is used as the brake booster 13 in the next routine.
Is used as an estimated value of the pressure. In this case, step S
According to 1-3, if the estimated pressure value of the brake booster 13 is higher than the pressure of the intake pipe 8, the brake booster 1
The pressure estimation value of 3 is the pressure value of the intake pipe 8.

According to FIG. 3, the estimated value of the pressure of the brake booster 13 changes greatly during the depression stroke of the brake pedal 2 (see period B), and thereafter becomes substantially constant. During the return stroke of the brake pedal 2 (see period C), the vehicle speed decreases due to the depression of the brake pedal 2 and the negative pressure of the intake pipe 6 decreases accordingly. Again, the change becomes large.

As described above, when the brake pedal 2 is not depressed, the estimated pressure value of the brake booster 13 is higher than the pressure of the intake pipe 8. It is said. On the other hand, when the brake pedal 2 is depressed, the pressure change amount of the brake booster 13 is obtained from the stroke amount, and the pressure estimated value of the brake booster 13 is obtained based on the obtained change amount. Thereby, a more accurate pressure estimation value corresponding to the actual pressure of the brake booster 13 can be obtained.

According to the above control, it is not necessary to use a relatively expensive pressure sensor as in the conventional configuration.
Since the pressure estimation value can be easily obtained using the existing configuration, the cost of parts can be reduced.

Further, if the above estimated pressure value is used in, for example, drive control of an air conditioner or control of an internal combustion engine, the air conditioner can be turned off or the combustion method can be changed in an appropriate state. Therefore, control for improving the effectiveness of the brake booster 13 can be appropriately performed. Further, according to the above-described control, since control such as estimating the pressure due to various factors such as the vehicle speed is not performed unlike the related art, the control becomes easier and the program is simplified.

In the present embodiment, the above-described control is performed using the stroke sensor 3. However, the above-described stroke sensor 3 can be used for other controls. For example, the stroke sensor 3 uses an ABS (Antilock Brake S
ystem), vehicle side slip control, brake assist control, and the like, so that the versatility of the pressure estimation device can be improved.

Of course, the scope of the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the stroke sensor 3 that detects the stroke amount of the brake pedal 2 is used to determine the pressure change amount of the brake booster 13. However, instead of this, a push rod connected to the brake pedal 2 is used. A sensor for detecting the stroke amount of 16 may be used, a treading force sensor for detecting the treading force of the brake pedal 2 may be used, or a hydraulic pressure sensor of brake oil may be used. In this case, the stroke amount of the brake pedal 2 may be determined from the outputs of these sensors to determine the amount of change in the pressure of the brake booster 13, or the pressure of the brake booster 13 may be determined directly from the outputs of these sensors. The amount of change may be determined.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a pressure estimating device for a brake booster according to the present invention.

FIG. 2 is a flowchart showing a control operation of the electronic control unit.

FIG. 3 is a timing chart of an estimated pressure value of a brake booster.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic control unit (ECU) 2 Brake pedal 3 Stroke sensor 6 Engine 8 Intake pipe 12 Pipeline 13 Brake booster 17 Brake switch 18 Memory

Claims (2)

[Claims] 1. A pressure estimating device for a brake booster for assisting operation of a brake pedal by utilizing a negative pressure of an engine, comprising: a sensor for detecting an operation amount of the brake pedal; and an operation amount of the brake pedal. Storage means for storing the relationship between the brake booster and the pressure change amount of the brake booster as data; and, based on the data stored in the storage means, the operation of the brake booster based on the operation equivalent of the brake pedal detected by the sensor. Determining means for determining a pressure change amount; and calculating means for calculating an estimated pressure amount of the brake booster based on the pressure change amount determined by the determining means. Estimation device. 2. The pressure estimating device for a brake booster according to claim 1, wherein said sensor detects a stroke amount of said brake pedal.