JP6886011B2 - How to operate a hydraulic braking system, hydraulic braking system - Google Patents

Description

The present invention is a method for driving a hydraulic brake system of an automobile, wherein the brake system has a brake pedal, a master brake cylinder connected to the brake pedal, and at least one wheel brake. It has two brake circuits, and relates to a method of automating and adjusting braking force amplification depending on brake pedal operation.

Furthermore, the present invention relates to a corresponding hydraulic brake system that has at least one brake booster and the brake force amplification can be adjusted by the brake booster.

The types of braking systems and methods mentioned at the outset are known in the art. Automobiles are usually equipped with a hydraulic braking system, which can also generate braking force for each wheel when the driver of the vehicle operates the brake pedal. In this case, a brake booster is usually arranged correspondingly to the master brake cylinder, and this brake booster is configured as a vacuum brake booster in a general form, and is added to the brake pedal by the driver. Since the applied force is amplified and brought into the hydraulic braking system or hydraulic circuit, for example, the legally required normal braking action can be obtained. Thus, the brake booster provides the required assist force while at the same time producing the sensation of a brake pedal with a pronounced reaction characteristic curve that is common to drivers. This characteristic curve has a deceleration based on the mechanical structure of the vacuum brake booster in the general form before a perceptually high reaction force acts against the driver. The time when the reaction force becomes correspondingly high is also called the jump-in time or the jump-in effect.

Known vacuum brake boosters use their functional principles with respect to power assist to always provide pedal effort and braking force or vehicle deceleration for the driver, despite the varied volume accommodation of each wheel brake. Further guarantee that the correlation and reproducibility between the two will be obtained.

The method according to the present invention having the feature of claim 1 is a brake booster mechanically separated from the brake pedal by a controllable brake booster without causing an unexpected feeling to the driver on the brake pedal. It has the advantage that braking force amplification can be generated by the device. In particular, the method of the present invention guarantees a correlation between pedaling force and vehicle deceleration, so that the driver always feels at ease when maneuvering the vehicle. This is because, according to the present invention, braking force amplification is produced by at least a controllable pressure generator in the brake circuit, on the one hand depending on the brake pedal operation and on the other hand in the master brake cylinder or wheel brake. It is obtained by being produced depending on the hydraulic pressure of. By controlling the pressure generator, on the one hand, depending on the operation of the brake pedal and, on the other hand, on the pressure in the master brake cylinder or wheel brake, on the one hand, it is desired to generate the desired braking force. Volume is transferred into each wheel brake, while the pressure in the master brake cylinder is guaranteed to be maintained or adjusted to give the driver a driving sensation familiar to the driver. ..

According to a preferred development of the present invention, the brake pedal operation is detected by the pedal stroke sensor. That is, the brake pedal operation is detected by the stroke sensor. In this case, the pedal stroke is measured and the pressure generator is controlled depending on the measured pedal stroke, which in particular calculates the target pressure or target pressure for the master brake cylinder, and thus the driver reaction force. To.

For this reason, preferably, the target pressure or reaction force is determined using the characteristic map and / or the characteristic curve depending on the detected brake pedal operation.

Further, depending on the brake pedal operation, the target pressure for the wheel brake is preferably determined. As a result, the target pressure of the wheel brake is calculated by the operation of the brake pedal or the detected pedal stroke. This is done in particular, in addition to or selectively in the calculation or determination of the target pressure of the master brake cylinder. Since each calculated target pressure is used as a target value when controlling the pressure generator, only one target value, preferably the target pressure of the master brake cylinder, and selectively the target pressure of the wheel brake can be set. In use, if the others do not reach or exceed an uncontrolled target value, the target values are properly matched so that a mutually correlative change in the two target values is obtained.

Preferably, the pressure generator is controlled depending on the brake pedal operation based on the assumed volume capacity of the wheel brake. By knowing the volume capacity of the brake circuit, especially the wheel brakes, the pressure generator allows unnecessary volume to be moved into the brake circuit or into each wheel brake due to the pressure rise in the master brake cylinder. , Controlled. Preferably, pressure control is superimposed on this in consideration of the pressure in the master brake cylinder, and in this pressure control, the pressure in the brake circuit and the pressure in the master brake cylinder are set to the desired brake at the desired wheel pressure. The control of the pressure generator to maintain or adjust to obtain the pedal / reaction force characteristic curve, as well as the control of one or more valves in the brake circuit, are adequately adapted. In this case, the target pressure characteristic curve or reaction force characteristic curve of the master brake cylinder over the pedal stroke reproduces the change in pedal force of the vacuum brake booster in order to provide the pedal feeling familiar to the driver. Should be configured as follows.

To this end, the pressure generator is controlled depending on the target pressure or target pressure characteristic curve that provides the appropriate pedal feel for the master brake cylinder or wheel brake.

The target pressure characteristic curve is preferably moved by an offset value depending on the idle stroke, especially the prefilling of the air gap and / or brake circuit. As a result, in particular, the pressure in the master brake cylinder is maintained at no pressure or 0 bar until the time of jump-in, and then the reaction force increases only after that. This results in the desired conventional pedal effort change for the driver. It is advantageous that the increase in pedal pedal effort until the jump-in force is obtained is particularly satisfied by a spring device arranged corresponding to the brake pedal. The offset value is particularly determined as the difference between the predetermined hydraulic stroke obtained at the end of the jump-in and the stroke stored in the target characteristic curve. In this case, the hydraulic pressure to be obtained does not necessarily have to be the pressure at the end of the jump-in, and may instead be any hydraulic pressure below this value.

Further, preferably, the rigidity factor of the brake circuit is calculated in addition to the offset value, and is used for the target pressure characteristic curve. In particular, for this reason, the target pressure characteristic curve is moved by an offset value, whereby the target pressure and the actual pressure overlap each other at the time of jump-in. Then, the rigidity factor is calculated by the division process, and the return conversion is performed by the offset movement. From this stiffness factor, the scaling factor used for the target pressure characteristic curve is obtained, which gives the latest target pressure characteristic curve. This allows pedal effort and wheel pressure / vehicle motion to be associated with the vacuum brake booster, as in conventional vehicles, and the altered volume accommodation and braking system stiffness to change the pedal stroke at the desired deceleration. Guaranteed to produce only.

In the brake system according to the present invention having the feature of claim 9, the brake booster has a controllable pressure generator controlled by a specially configured control unit, and the control unit generates pressure. It is characterized in that the vessel is configured to be controlled according to the method according to the present invention. In this case, the above-mentioned advantages already mentioned can be obtained. Preferably, the brake pedal is correspondingly provided with a spring device that guarantees an increase in braking force or reaction force until the jump-in force is reached.

Preferably, the master brake cylinder and / or the wheel brake each has at least one hydraulic pressure sensor to detect the hydraulic pressure present in the master brake cylinder or wheel brake.

Further, preferably, since the brake pedal is provided with a corresponding pedal stroke sensor, the brake pedal operation is calculated by monitoring the brake pedal movement and particularly the stroke advanced by the brake pedal.

Further, preferably, the brake circuit has at least one operable switching valve between the master brake cylinder and the wheel brake. Since the switching valve is open especially in the no-current state, the brake pressure in the wheel brake can be increased at any time by operating the pedal. When the switching valve is energized, the connection between the brake circuit and the master brake cylinder is closed, so no pressure leaks from the brake circuit. In this case, since the switching valve is connected to the pressure generator especially on the discharge side, when the pressure generator is controlled, the pressure generated in the brake circuit is held in the brake circuit by the switching valve. Or be enhanced.

It is a simplified diagram of a brake system of an automobile. It is a diagram for demonstrating the braking force amplification. FIG. 6 is a diagram illustrating a preferred method for operating a braking system.

Other advantages and suitable features and combinations of features are specifically described above and in the claims. The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a simplified view of a hydraulic brake system 1 for an automobile, which is not shown in detail here. The brake system 1 is operated by the driver of the automobile using the brake pedal 2 when the driver wants to start the brake operation or the deceleration of the automobile. The brake pedal 2 is connected to the master brake cylinder 3. In this case, the brake pedal 2 may be directly or indirectly connected to the master brake cylinder 3 in order to move the piston in the master brake cylinder to generate hydraulic pressure.

The master brake cylinder 3 is fluidly connected to the brake circuit 4. Basically, the brake system 1 may have more than one brake circuit 4. Here, the brake circuit 4 has a high-pressure switching valve 5 and a switching valve 6 which are connected in parallel to each other. Like the switching valve 6, the high-voltage switching valve 5 is configured to be closed without current. Following the high-voltage switching valve 5, a discharge valve 7 which is also configured to be a non-current closed type is provided. Following the switching valve 6, a suction valve 8 configured to be a non-current open type is provided. Both the discharge valve 7 and the suction valve 8 are fluidly connected to the wheel brake 9 of the braking system, and the wheel brake 9 is arranged corresponding to one of the wheels of the automobile. The wheel brake 9 is constructed in a conventional manner and form, for this purpose in particular having at least one brake piston movably supported within the brake caliper, which brake piston is relative to the wheel. It can be operated by hydraulic pressure from the brake circuit 4 so that it can be tightened against the non-rotatably coupled brake disc. In this case, in particular, the brake discs are tightened between the brake linings of the wheel brakes 9 arranged facing each other, which causes friction between the brake linings and the brake discs, which is hydraulic. Brake torque is generated on the wheel depending on the braking force. A pressure sensor 10 is further arranged on the wheel brake 9, and the pressure sensor 10 monitors the hydraulic pressure in the wheel brake. Similarly, a pressure sensor 11 is provided correspondingly to the master brake cylinder 3, and the pressure sensor 11 calculates or detects the pressure of the master brake cylinder. Further, the suction side of the pressure generator 12 is fluidly connected between the high pressure switching valve 5 and the discharge valve 7. In this case, the discharge side of the pressure generator 12 brakes between the switching valve 6 and the suction valve 8. It is connected to the circuit 4. The pressure generator 12 is configured as an electrically driven pump in the embodiments of the present invention, which is always controlled by the control unit 13 of the brake system 1 with a switching valve and suction. The hydraulic pressure between the valve 8 or the wheel brake 9 can be increased.

In the operated / energized state, the high pressure switching valve 5 opens in the direction of the pressure generator 12, in which case the discharge valve 7 is in the operated or controlled state of the high pressure switching valve 7 or the pressure generator. Open in 12 directions. The switching valve 6 is opened in the direction of the master brake cylinder 3 and the direction of the suction valve 8 in the operated state. Similarly, the intake valve 8 opens in both directions, that is, in the direction of the switching valve 6 and the direction of the wheel brake 9.

The correlation between pedal effort and vehicle deceleration has been confirmed for electrical and vacuum-free braking force amplification in the closed braking system 1 described herein by the method described below performed by the control unit 13. It must be. In this case, the main components of the ESP system may be utilized. In particular, valves 4, 6, 7, 8 and pressure generators 12 are components of many existing ESP systems, which significantly reduces the structural additional cost of implementing this method.

According to the illustrated embodiment, the normally generally provided vacuum brake booster connected between the brake pedal 2 and the master brake cylinder 3 is omitted. Instead, braking force amplification or braking force support is automated by the pressure generator 12. Therefore, since the braking force amplification is generated by the pressure difference via the switching valve 6, the driver always obtains a retrofittable correlation between the pedaling force or reaction force and the braking force or vehicle deceleration. Therefore, the reaction force acting against the driver on the brake pedal must be controlled via the pedal stroke of the brake pedal 2.

Since the usable brake fluid volume of the brake system 1 is preset via the pedal stroke of the brake pedal 2, for example, by increasing the volume capacity of the wheel brake 9, the wheel pressure or the brake pressure is lowered, and the brake pressure is reduced. As a result, the deceleration of the vehicle is reduced. Nevertheless, the pressure in the master brake cylinder and, by extension, the reaction force acting against the brake pedal 2 or the driver is controlled according to the target characteristic curve of the master brake cylinder 3. Therefore, the correlation or reproducibility between the reaction force and the vehicle deceleration cannot be obtained, for example, when the volume fluctuation exceeds 30%. Therefore, without alternative means, the brake system 1 has a control target of the target pressure of the master brake cylinder that produces a corresponding reaction force and a control target of the wheel pressure of the wheel brake 9 that produces a corresponding deceleration of the automobile. , Cannot be obtained at the same time.

The correlation between reaction force and vehicle deceleration is confirmed by the method described below. That is, only one of the existing target values, preferably the target pressure of the master brake cylinder, or selectively the target pressure of the wheel brake 9, cannot be used to obtain another or uncontrolled target value. Or above this, the target values are properly matched, thereby resulting in a mutually correlative change in the two target values.

The brake pedal 2 is further provided with a pedal stroke sensor 14 that monitors the movement of the brake pedal 2. Depending on the detected pedal stroke of the brake pedal 2, the control unit 13 first uses the available characteristic curves that depend on each vehicle to determine the desired pressure in the brake pedal 2 to obtain the desired reaction force. Calculate. By knowing the volume accommodation of the brake system 1, the pressure generator 12 is controlled via pilot control in order to move the volume unnecessary for the pressure rise in the master brake cylinder 3 into the brake circuit 4. .. This is superposed with pressure control in a suitable form, using the pressure sensor 11 to adequately adapt both the control of the pressure generator 12 and the control of the switching valve 6.

In order to simulate the change in pedal pedal force or change in reaction force of the vacuum brake booster, the driver draws a target pressure characteristic curve that expresses the target pressure or target pressure of the master brake cylinder over the movement stroke of the brake pedal 2. Despite the automated braking force support without a vacuum brake booster, it is configured to give the driver a familiar driving feel. The so-called "JumpIn-Effect" "jump-in effect" is obtained by keeping the target pressure characteristic curve of the master brake cylinder 3 at 0 bar without pressure until the time of jump-in.

Therefore, FIG. 2, the pedal pressing force F _P acting against the driver as a reaction _force, the pressure p ₃ of the master brake cylinder 3 and the pressure p ₉ of the wheel brakes _9, are respectively over the pedal stroke s The three diagrams shown in the above are shown in a simplified diagram. In this case, it can be seen that at the initial position, the pedal depression force F ₂ starts from 0 bar pressures p ₃ and p _{9, respectively.} In the first motion section of the brake pedal 2 up to position s _1, only the _{reaction force F 2} is increased by the spring device 15, which is arranged corresponding to the brake pedal 2 and is simply illustrated in FIG. When overcoming the stroke s _1, increases from this point, as can be seen by the pressure p ₉ in the wheel brake 9, jump-in effect to take effect. As mentioned above, at this point, the pressure p3 in the master brake cylinder ₃ is first kept at 0 bar. Only at the delayed stroke point s ₂ after overcoming the jump-in effect, the pedal depression force F _{2 and the pressure p 3} in the master brake cylinder 3 rise.

FIG. 3 shows how the target pressure characteristic curve of the master brake cylinder 3 shown in FIG. 2 is defined, and how the braking force characteristic familiar to the driver in the brake pedal 2 is felt. In this case, the actual value or the actual characteristic curve is shown by a solid line, and the target value or the target characteristic curve is shown by a broken line.

First, it is calculated at which pedal stroke s the jump-in effect (s ₁ ) starts (A). The stroke movement amount Δs is calculated from the corresponding value from the target pressure characteristic curve. In order to properly adjust the jump-in effect within the pressure of the master brake cylinder 3, the target pressure for the master brake cylinder is 0 bar up to this calculated stroke. Therefore, the target pressure characteristic curve of the pressure p ₃ in the master cylinder 3, optionally in order to correct the preliminary filling of the air gap or brake system 1 increased exists, is moved by the offset value Delta] s.

In this hydraulic brake system 1, the rigidity of the brake circuit 4 can be further changed. This can be corrected via the stiffness factor f. This is the stroke point at which the target pressure characteristic curve of the wheel brake 9 is moved by the calculated offset value Δs so that the target pressure and the actual pressure start at this point or the jump-in effect. It is calculated by overlapping each other as shown in (B). The stiffness factor f is calculated by the division process, and is back-converted by the offset movement. This is then used as a scaling factor in the target pressure characteristic curve of the master brake cylinder 3 so that the latest target pressure characteristic curve K3 for the master brake cylinder ₃ is calculated online (C). Thereby, the reaction force and wheel pressure or vehicle deceleration in the brake pedal 2 are associated with each other as in a normal vehicle equipped with a vacuum brake booster, and the varied volume accommodation and rigidity of the brake system 1 are desired. It is guaranteed that only the pedal stroke change during deceleration will occur.

In a preferred form, the method is used while driving a car. The average long-term value can be stored and, in some cases, the long-term value can be used as a default value, for example, if online fit is not available. Situations that cannot be evaluated are, for example, emergency braking or braking with high operational dynamics that results in erroneous calculations due to time delays and dynamic pressures. For example, even at extremely low temperatures of T <-30 ° C., the amplified dynamic pressure effect and the reduced pumping amount of the pressure generator 12 must be taken into account based on the characteristics of the hydraulic medium used. Preferably the stored long-term value is used.

Here, in this method, the pressure of the master brake cylinder 3 is controlled according to the wheel pressure or the pressure deviation of the wheel brake 9, whereas according to another embodiment, this is the same. Since it is performed in reverse, the pressure in the wheel brake 9 or the control of the wheel pressure is performed in accordance with the pressure deviation of the master brake cylinder 3.

1 Brake system 2 Brake pedal 3 Master brake cylinder 4 Brake circuit 6 Switching valve 8 Rigidity factor 9 Wheel brake 10,11 Hydraulic pressure sensor, pressure sensor 12 Pressure generator 13 Control unit 14 Pedal stroke sensor Δs Stroke movement amount, offset value

Claims (10)

A method for driving a hydraulic brake system (1) of an automobile, wherein the brake system (1) is connected to a brake pedal (2) and a master brake cylinder (3) connected to the brake pedal (2). ) And at least one brake circuit (4) having at least one wheel brake (9), in a method of automating and adjusting braking force amplification depending on brake pedal operation.
Braking force amplification depends on at least a controllable pressure generator (12) in the brake circuit (4), on the one hand, to brake pedal operation to ensure a correlation between pedal effort and vehicle deceleration. On the other hand, it is produced depending on the hydraulic pressure in the wheel brake (9).
For the master brake cylinder (3), which represents the target pressure of the master brake cylinder (3) over the motion stroke of the brake pedal (2) in order to simulate a change in pedal pressure of the vacuum brake booster. The pressure generator (12) is controlled according to the target pressure characteristic curve.
The target pressure curve, depending on the idle stroke, is moved by the offset value (Delta] s), characterized that you calculate the latest of the target pressure characteristic curve online, operating a braking system of a hydraulic Method for. A method for driving a hydraulic brake system (1) of an automobile, wherein the brake system (1) is connected to a brake pedal (2) and a master brake cylinder (3) connected to the brake pedal (2). ) And at least one brake circuit (4) having at least one wheel brake (9), in a method of automating and adjusting braking force amplification depending on brake pedal operation.
Braking force amplification depends on at least a controllable pressure generator (12) in the brake circuit (4), on the one hand, to brake pedal operation to ensure a correlation between pedal effort and vehicle deceleration. On the other hand, it is produced depending on the hydraulic pressure in the wheel brake (9).
For the master brake cylinder (3), which represents the target pressure of the master brake cylinder (3) over the motion stroke of the brake pedal (2) in order to simulate a change in pedal pressure of the vacuum brake booster. The pressure generator (12) is controlled according to the target pressure characteristic curve.
The target pressure characteristic curve is moved by an offset value (Δs) depending on the air gap and / or the prefilling of the brake circuit (4), and the latest target pressure characteristic curve is calculated online. A method for operating a hydraulic braking system. The method according to claim 1 or 2 , wherein the brake pedal operation is detected by a pedal stroke sensor (14). The method according to any one of claims 1 to 3 , wherein the target pressure of the master brake cylinder (3) is determined depending on the detected brake pedal operation. The method according to any one of claims 1 to 4 , wherein a target pressure for the wheel brake (9) is determined depending on the operation of the brake pedal. Any of claims 1 to 5 , characterized in that the pressure generator (12) is controlled depending on the brake pedal operation based on the assumed volume accommodation of the wheel brake (9). The method described in item 1. A hydraulic brake system (1) for automobiles, which includes a brake pedal (2), a master brake cylinder (3) connected to the brake pedal (2), and at least one wheel brake (9). In a type having at least one brake circuit (4) having the brake circuit (4) and having at least one brake booster correspondingly arranged in the brake circuit (4).
The brake booster has a controllable pressure generator controlled by a specially configured control unit (13), which claims the pressure generator (12). A hydraulic brake system, characterized in that it is configured to be controlled according to the method according to any one of items 1 to 6. The brake system according to claim 7, wherein the master brake cylinder (3) and / or the wheel brake (9) each has at least one hydraulic pressure sensor (10, 11). The brake system according to claim 7 or 8, wherein a pedal stroke sensor (14) is provided correspondingly to the brake pedal (2). A claim, wherein the brake circuit (4) has at least one operable switching valve (6) between the master brake cylinder (3) and the wheel brake (9). The brake system according to any one of 7 to 9.

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