阅读说明：本技术 用于求取可供使用的液体体积的方法和设备、制动系统 (Method and device for determining a volume of available fluid, and brake system ) 是由 F·哈格 M·马夸特 N·洛夫曼 于 2021-06-15 设计创作，主要内容包括：本发明涉及一种用于求取在用于制动系统(1)的制动液的储罐(2)中的可供使用的液体体积的方法,其中所述制动系统(1)带有一方面与所述储罐(2)并且另一方面与至少一个制动回路(8)流体技术地连接的压力产生器(4、9),所述压力产生器能够被操控用于在从所述储罐(2)中提取制动液的情况下在所述制动系统(1)中产生液压压力,并且其中借助于分配给所述储罐(2)的二元传感器(11)监测低于用于在所述储罐(2)中的制动液的填充水平的预先给定的极限值(F)。规定了：监测所述压力产生器(4、9)的操纵,并且在当前的填充水平低于所述极限值(F)时,根据所述压力产生器(4、9)的操纵来求取可供使用的液体体积。(The invention relates to a method for determining a volume of liquid available in a reservoir (2) for brake fluid of a brake system (1), wherein the brake system (1) has a pressure generator (4, 9) which is fluidically connected on the one hand to the reservoir (2) and on the other hand to at least one brake circuit (8) and which can be actuated for generating a hydraulic pressure in the brake system (1) when brake fluid is withdrawn from the reservoir (2), and wherein a predefined limit value (F) below a filling level for brake fluid in the reservoir (2) is monitored by means of a binary sensor (11) assigned to the reservoir (2). Provision is made for: the actuation of the pressure generator (4, 9) is monitored and, if the current fill level is below the limit value (F), the available liquid volume is determined as a function of the actuation of the pressure generator (4, 9).)

1. Method for determining a fluid volume available in a reservoir (2) for brake fluid of a brake system (1), wherein the brake system (1) has a pressure generator (4, 9) which is fluidically connected on the one hand to the reservoir (2) and on the other hand to at least one brake circuit (8) and which can be actuated for generating a hydraulic pressure in the brake system (1) when brake fluid is withdrawn from the reservoir (2), and wherein a predefined limit value (F) below a filling level for brake fluid in the reservoir (2) is monitored by means of a binary sensor (11) assigned to the reservoir (2), characterized in that the actuation of the pressure generator (4, 9) is monitored and, if a current filling level is below the limit value (F), the available liquid volume is determined as a function of the actuation of the pressure generator (4, 9).

2. Method according to claim 1, characterized in that the pressure generator (4, 9) is monitored with respect to the manipulated volume of the hydraulic pressure of the brake fluid transferred by the pressure generator (4, 9).

3. Method according to any one of the preceding claims, characterized in that the pressure generator (4) is a controllable hydraulic cylinder (5), in particular a master brake cylinder, with at least one movable hydraulic piston (6), and that the control volume is determined on the basis of the movement of the hydraulic piston.

4. Method according to any of the preceding claims, characterized in that the pressure generator (9) is a drivable rotary pump (10) and that the manipulated volume is determined on the basis of the duration of the drive and the rotational speed of the rotary pump.

5. Method according to any of the preceding claims, characterized in that the available liquid volume is determined on the basis of the ascertained manipulated volume and the cross-sectional area of the tank (2).

6. Method according to any of the preceding claims, characterized in that at least one valve (7) is connected after the hydraulic cylinder (5), by means of which valve the return flow of brake fluid from the brake circuit (8) into the hydraulic cylinder (5) is prevented when the hydraulic piston (6) is pushed back into the starting position with the extraction of brake fluid from the reservoir (2).

7. Method according to one of the preceding claims, characterized in that the method is carried out periodically, in particular after each start of operation of the motor vehicle in the standstill state of the motor vehicle and/or at each standstill of the motor vehicle.

8. Method according to one of the preceding claims, characterized in that the available fluid volumes determined by carrying out the method a plurality of times are compared with one another and in the event of a falling fluid volume being detected, a leak in the brake system (1) is detected.

9. Method according to any of the preceding claims, characterized in that for a functional check a manipulated volume is moved by the pressure generator (4, 9), as a result of which a limit value (F) in the tank (2) should be lowered, and in particular a functional error of the binary sensor (11) is recognized when the binary sensor does not recognize the lowering.

10. A device for determining a liquid volume available in a reservoir (2) for brake fluid of a brake system (1), wherein the brake system (1) has a pressure generator (4, 9) which is fluidically connected on the one hand to the reservoir (2) and on the other hand to at least one brake circuit (8) and which can be actuated for generating a hydraulic pressure in the brake system (1) when brake fluid is withdrawn from the reservoir (2), and wherein a predefined limit value (F) below a filling level for brake fluid in the reservoir (2) is monitored by means of a binary sensor (11) assigned to the reservoir (2), characterized by being designed as a controller (14) which is specifically set up for: the method according to any one of claims 1 to 9 is carried out in a compliant application.

11. A brake system (1) for a motor vehicle, having a reservoir (2) and at least one brake circuit, wherein a pressure generator (4, 9) is connected on the one hand to the reservoir (2) and on the other hand to at least one brake circuit (8) and is designed to: generating a hydraulic pressure in at least one brake circuit (8) when brake fluid is drawn from the reservoir (2); and with a binary sensor (11) assigned to the reservoir (2) for detecting a falling below a predefined limit value (F) for the filling level of brake fluid in the reservoir (2), characterized by a device according to claim 10.

Technical Field

The invention relates to a method and a device for determining a volume of available liquid in a brake fluid reservoir for a brake system, wherein the brake system has a pressure generator which is fluidically connected on the one hand to the reservoir and on the other hand to at least one brake circuit and which can be actuated for generating a hydraulic pressure in the brake circuit in the event of brake fluid being withdrawn from the reservoir, and wherein a predefined limit value below a filling level for the brake fluid in the reservoir is monitored by means of a binary sensor assigned to the reservoir.

The invention further relates to a brake system having a reservoir for brake fluid; with at least one brake circuit and with a pressure generator which is fluidically connected on the one hand to the reservoir and on the other hand to the at least one brake circuit, the pressure generator being designed to: generating a hydraulic pressure in at least one brake circuit in the event of brake fluid being drawn from the reservoir; wherein the reservoir is assigned a binary sensor for monitoring a filling level of the brake fluid in the reservoir.

Background

Methods of the type mentioned at the outset are known from the prior art. Hydraulic brake systems are often equipped with a reservoir or a liquid tank, in which brake fluid for the brake system is supplied. In order to ensure that the brake fluid does not fall below a predetermined limit volume, the filling level of the brake fluid in the reservoir is monitored by means of a filling level sensor. For cost reasons, binary sensors are often arranged at the tank, which monitor that the filling level is below a predetermined limit value. If the fill level is below a predetermined limit value, this is detected by the binary sensor and reported. However, no conclusions can be drawn therefrom as to the volume of liquid actually present.

Disclosure of Invention

This is achieved by the method according to the invention with the features of claim 1: although binary sensors are used for monitoring the fill level of the brake fluid in the reservoir, conclusions can be drawn about the quantification of the volume of fluid actually present in the brake system or that can be expanded without complex sensor technology having to be applied for this purpose. Thus, according to the invention: the actuation of the pressure generator is monitored and, if the current fill level is below the limit value, the available liquid volume is determined as a function of the actuation of the pressure generator. The invention therefore provides for: the actuation of the pressure generator is monitored, whereby it is possible to determine how large the hydraulic volume from the reservoir to the brake system is moved by the pressure generator. From the ascertained displaced hydraulic volume, it can be determined: how much the filling level in the tank drops due to the operation of the pressure generator. From the binary sensor a point in time below the limit value is reported or determined, whereby from the moved volume and below the limit value the filling level in the tank before the pressure generator is operated can be calculated. The fill level present in the reservoir before the pressure generator is actuated is understood to be the available brake fluid volume. This makes it possible to implement in a simple manner: in consideration of the actuation of the pressure generator in the brake system, the actually available fluid volume in the reservoir is determined by using a binary sensor, so that, for example, an early warning signal can be output if the actually available fluid volume falls below a predetermined limit value.

The pressure generator is preferably monitored with respect to the manipulated volume of the hydraulic pressure of the brake fluid transferred by the pressure generator. In principle, it is sufficient to monitor the actuation of the pressure generator for estimating the available fill level, while the accuracy of the estimation is improved by determining the hydraulic actuation volume. Knowing the application of the pressure generator, the actuating volume which is moved from the reservoir into the brake circuit by the pressure generator can be calculated with low effort.

The pressure generator is preferably an actuatable hydraulic cylinder, in particular a master brake cylinder of a brake system, which has at least one movably mounted hydraulic piston, and an actuation volume is determined as a function of the displacement of the hydraulic piston. In particular, the displacement distance of the hydraulic piston is monitored or determined as a function of the actuation of the pressure generator, and the displaced hydraulic volume is determined thereby taking into account the end face of the hydraulic piston.

According to an alternative embodiment of the invention, the pressure generator is a drivable rotary pump and the actuating volume is determined as a function of the duration of the drive and the rotational speed of the rotary pump. With knowledge of the power data of the rotary pump, in particular the delivery rate dependent on the rotational speed, the displaced hydraulic volume can likewise be determined without a large additional expenditure.

According to a preferred development of the invention, the available liquid volume is determined as a function of the ascertained operating volume and the cross-sectional area of the tank. In particular, the displaced hydraulic volume is divided by the cross-sectional area of the reservoir, whereby the original filling level of the brake fluid in the reservoir is obtained, which corresponds to the sought available liquid volume.

Preferably, at least one valve is connected downstream of the hydraulic cylinder, by means of which valve a return flow of brake fluid from the brake circuit into the hydraulic cylinder is prevented when the hydraulic piston is pushed back into the starting position with a withdrawal of brake fluid from the reservoir. Since the hydraulic cylinder or the hydraulic cylinders cannot draw hydraulic medium from the reservoir during the advancing process in which hydraulic pressure is generated, the brake fluid is preferably prevented from flowing back from the brake circuit into the brake cylinder by means of the valve when the piston is pulled back into the starting position. The hydraulic cylinder then draws brake fluid from the reservoir when it is pulled back, and thus changes the filling level in the reservoir. The hydraulic volume that is displaced into the hydraulic cylinder when the hydraulic piston is pushed back generally then corresponds to the required actuation volume of the pressure generator.

Preferably, the method is carried out periodically, in particular after each start of operation of the motor vehicle in the standstill state of the motor vehicle and/or at each standstill of the motor vehicle. This ensures that the brake system is regularly monitored, which does not adversely affect the driving behavior of the vehicle. In this case, the start operation of the motor vehicle is understood as the start (ignition) of the motor vehicle, and the stop operation is understood as the shut-down (ignition-off) of the motor vehicle.

Furthermore, it is preferably provided that: for the functional checking of the binary sensor, a manipulated volume is moved by the pressure generator, as a result of which a limit value into the tank is to be lowered, and a functional error of the binary sensor is detected if the binary sensor does not recognize a lowering below the limit value. The pressure generator is controlled in such a way that it displaces a sufficiently large actuating volume, which normally leads to a filling level below a predetermined limit value. However, if it is not recognized by the binary sensor, there is an error of the binary sensor in particular.

The device according to the invention having the features of claim 10 is characterized by being configured as a controller which is specifically set up for: the method according to the invention is carried out in a suitable application.

The brake system according to the invention with the features of claim 11 is characterized by the device according to the invention. This results in the already mentioned advantages.

Drawings

Further advantages and preferred features and combinations of features result, in particular, from the foregoing description and from the claims. The invention is intended to be read in more detail hereinafter with the aid of the accompanying drawings. Wherein:

fig. 1 shows an advantageous braking system in a simplified view; and is

Fig. 2 shows a flow chart for illustrating an advantageous method for determining the available liquid volume in a brake system.

Detailed Description

Fig. 1 shows an advantageous brake system 1 of a motor vehicle, which is not shown in detail here, in a simplified view. The brake system 1 has a reservoir 2 for receiving and storing a liquid brake medium 3. The reservoir 2 is fluidically connected to a pressure generator 4, which, according to an exemplary embodiment of the present invention, is designed as a hydraulic cylinder 5 with a hydraulic piston 6 mounted therein in a displaceable manner. On the outlet side, the pressure generator 4 is fluidically connected to a controllable valve 7, which selectively releases or locks the connection of the pressure generator 4 to a brake circuit 8. The valve 7 is designed, for example, as a solenoid-operated switching valve. Optionally, in addition to or as an alternative to the pressure generator 4, there is a further pressure generator 9, which is configured as a rotary pump 10 according to an embodiment of the invention. If the pressure generator 9 is additionally present, it is advantageously connected between the pressure generator 4 and the valve 7.

Furthermore, the tank 2 is assigned a binary sensor 11. The binary sensor 11 is arranged at a side wall 12 of the reservoir and, when the brake fluid 3 is at the level of the binary sensor 11, a first signal is given and, when the brake fluid 3 is not in the region of the binary sensor 11, a second signal is given, so that, for example, only a gas volume, in particular an air volume, is present in the reservoir 2 at the level of the binary sensor 11. The binary sensor 11 is arranged at a height of the side wall 12, which corresponds to a predefined limit value F for the filling level of the brake medium 3 in the reservoir 2. If the level 13 of the brake medium 3 falls below the predefined limit value F, the binary sensor 11 changes its signal and thus reports that the brake medium 3 in the reservoir 2 falls below the predefined filling state.

Furthermore, the brake system 1 has a controller 14, which is connected in signal-technical fashion at least to the binary sensor 11, the pressure generators 4 and/or 9 and the valve 7. For reasons of clarity, the signal connections are not shown in fig. 1.

The controller 14 is designed to control the pressure generators 4 and/or 9 and the valve 7 and to evaluate the signals of the binary sensor 11. For this purpose, the controller 14 executes the method represented by the flow chart in fig. 2 in the motor vehicle or in the brake system 1 in the case of a suitable application.

The method begins in step S1 with the start of operation (ignition) of the motor vehicle. Subsequently in step S2, the existing pressure generator 4, 9 is monitored with regard to its actuation and at the same time the data of the binary sensor is monitored in step S3. If it is determined in step S2 that the at least one pressure generator 4, 9 is operated, but the fill level sensor 11 has not yet reported a value below the limit value (j) in step S3, then in step S4: still sufficient brake fluid or sufficient liquid volume is present in the reservoir 2. If, however, it is recognized that the binary switch 11 reports a fill level (n) below a predefined level, in a step S5 following this, the hydraulic volume displaced by the pressure generator 4, 9 during its actuation from the reservoir 2 in the direction of the brake circuit 8 is calculated as a function of the detected actuation of the respective pressure generator 4, 9 and the point in time below the limit value. Knowing the displaced hydraulic volume, the original filling level of the tank 2 is calculated. To this end, in particular, the displaced hydraulic volume is divided by the area of the reservoir 2. The original filling level is thus obtained as the height in the tank 2. For this purpose, fig. 1 shows, for example, the state of the tank 2, in which the binary sensor 11 reports or triggers a undershooting of the limit value F.

In step S6, the thus determined initial filling state of the reservoir 2 is compared with a predefined limit value for the available fluid volume in the brake system 1. If the calculated value is not below the predefined limit value (j), a sufficient filling state is detected in step S4 and the motor vehicle 1 is operated as usual. If, however, it is determined in step S6 that the calculated available volume is below the limit value (n), then in a step S7 following this, a warning signal, for example in acoustic or visual form, is output to the driver of the motor vehicle.

In order to determine the actuating volume, the displacement distance of the piston 6 in the hydraulic cylinder 5 is detected on the basis of the pressure generator 4, in order to calculate the displaced hydraulic volume taking into account the cross section of the hydraulic cylinder 5 or the end face of the piston 6. Provision is preferably made here for: after the hydraulic piston has moved the hydraulic volume in the brake circuit 8, the actuating volume is then calculated when the hydraulic piston 6 is moved back into the pulled-back starting position. For this purpose, the valve 7 is closed when the hydraulic piston 6 is retracted. This results in the pressure generator 4 sucking up brake fluid 3 from the reservoir 2 in order to fill the now free volume in the hydraulic cylinder 5. In this way, the actuating volume is determined not in the power stroke of the hydraulic piston 6 but in the return position.

In relation to the pressure generator 9, the rotational speed and the rotational duration of the rotary pump 10 are monitored in particular for determining the actuation volume, and the actuation volume is calculated with knowledge of the power characteristic of the rotary pump 9.

The advantageous brake system 1 or the described method has the following advantages: although only one binary sensor 11 is arranged at the tank 2, a path-resolved conclusion can be made about the liquid volume actually present in the brake system. The method is advantageously carried out after each start of operation of the motor vehicle 1 and/or with a standstill of the motor vehicle. Preferably, the ascertained and calculated values are permanently stored in order to detect the curve of the ascertained liquid volume. If the liquid volume decreases permanently, it is concluded that: in the brake system 1, a leak is present and, for example, an alarm signal is output in order to be able to take countermeasures early.

Furthermore, with an advantageous braking system 1 it is possible to realize: the functional capability of the fill level sensor or binary sensor 11 is monitored. For this purpose, the pressure generator 4 and/or 9 is/are actuated for displacing a hydraulic volume which is so large that the filling level of the brake fluid 3 in the reservoir 2 should be below the limit value F. If the binary sensor 11 does not recognize it, i.e. the binary sensor is not triggered, it is determined that there is a faulty functioning of the binary sensor 11.