Method for calculating auxiliary power cylinder pressure and apparatus for carrying out the method - Patent Application 20070122997

Abstract

The present invention provides a corrected virtual auxiliary power cylinder pressure (p F ) is calculated. This method includes calculating at least one motor value (M M ) and a step (A) of calculating the motor value (M M ) and the virtual auxiliary power cylinder pressure (p F ) correlation model (p F (M M )) to calculate the motor value (M M ) to the virtual auxiliary power cylinder pressure (p F ) in the ESP brake system (8) by the ESP pressure sensor (36), and ESP and (C) calculating the virtual auxiliary power cylinder pressure (p F ) and the auxiliary power cylinder pressure (p ESP ) and the virtual auxiliary power cylinder pressure (p F ) to the auxiliary power cylinder pressure (p ESP ) and a step (D) of comparing the calculated deviation (Δp) with the correlation model (p F (M M and (E) correcting the

Description

[Technical Field]

[0001] The present invention relates to a method for calculating an auxiliary power cylinder pressure of an auxiliary power brake system. [Background technology]

[0002] Today's power-assisted braking systems are advantageous in that they are mechanically and / or hydraulically connected to the driver. This is done via a brake pedal connected to an input rod. The driver's braking request is detected within the entire system via this input rod, and a pedal feel in the form of a force-stroke characteristic curve is realized. Pressure is then generated via a power-assisted piston, which is hydraulically isolated from the driver's foot. To control this pressure generation, the brake pressure generated via the power-assisted piston is measured via a pressure sensor. Then, at a fallback level, muscle-operated brake cylinders connect the driver's foot to the wheel brake cylinders, allowing the driver to apply brake pressure using their foot. This allows the vehicle to remain brakeable even in the event of a breakdown.

[0003] Patent Document 1 discloses an electrohydraulic auxiliary power vehicle braking system for an autonomous land vehicle. Such an electrohydraulic auxiliary power vehicle braking system includes two redundant auxiliary power brake pressure generators, so that during autonomous driving and in the event of a failure of one auxiliary power brake pressure generator, the other auxiliary power brake pressure generator can brake the vehicle without driver intervention.

[0004] Similarly, Patent Document 2 discloses an electrohydraulic auxiliary power vehicle brake system. In this electrohydraulic auxiliary power vehicle brake system, the auxiliary power brake pressure generator is configured as a piston-cylinder unit, which is connected to a pressureless brake fluid reservoir tank by a pressure limiting valve and a controllable valve. The pressure of the auxiliary power brake pressure generator is measured via a pressure sensor arranged in the piston-cylinder unit. The pressure limiting valve prevents pressure peaks in the vehicle brake system when the intake valves of the hydraulic wheel brakes of the vehicle brake system are closed during pressure generation by the auxiliary power brake pressure generator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Publication No. 102018222488 [Patent Document 2] German Patent Publication No. 102019201536 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to provide a method for calculating the auxiliary power cylinder pressure, which allows the calculation of the auxiliary power cylinder pressure to be performed economically, and further to provide an apparatus for carrying out the method. [Means for solving the problem]

[0007] This problem is solved by a method for calculating the auxiliary power cylinder pressure having the features of claim 1. Additionally, a device for carrying out the method is provided. The respectively cited dependent claims provide preferred embodiments of the invention.

[0008] The present invention provides a method for calculating an assist power cylinder pressure in an assist power brake system, the method including the steps of calculating at least one motor value of an assist power cylinder motor, calculating a virtual assist power cylinder pressure from the motor value using a correlation model between the motor value and a virtual assist power cylinder pressure, and calculating the assist power cylinder pressure with an ESP pressure sensor in an ESP brake system. The method further includes the steps of comparing the virtual assist power cylinder pressure with the assist power cylinder pressure of the ESP pressure sensor, taking into account a time delay between the virtual assist power cylinder pressure and the measured assist power cylinder pressure of the ESP pressure sensor, and modifying the correlation model according to the calculated deviation.

[0009] In this case, the auxiliary power cylinder pressure is understood to be the pressure generated by the auxiliary power cylinder to generate braking force. In the prior art, this pressure is usually calculated via a pressure sensor arranged directly downstream of the auxiliary power cylinder. In this case, the virtual auxiliary power cylinder pressure is not a measured pressure but a calculated pressure. From this virtual pressure, it is assumed that this pressure corresponds to the measured pressure. However, due to uncertainties in the calculation, there may be a small error. In the sense of the present invention, the motor value is understood to be a measured value that depends on the operating state of the motor and changes over time. In a preferred embodiment, the motor value is calculated using known values, so that no additional measurement sensor is required.

[0010] The correlation model may be configured as a mathematical function, for example, and the auxiliary power cylinder pressure can be calculated for all motor values ​​via this model. This correlation model includes all factors that affect the auxiliary power cylinder pressure. Since it is difficult to take into account environmental conditions such as temperature or wear of the auxiliary power brake device, high accuracy of the calculated auxiliary power cylinder pressure can be achieved by constantly correcting the correlation model. The time delay is a time value by which the auxiliary power cylinder pressure calculated by the ESP pressure sensor is delayed in time relative to the actual pressure or the virtual auxiliary power cylinder pressure calculated via the correlation model.

[0011] This method allows the auxiliary power cylinder pressure to be accurately calculated without using a pressure sensor, thereby saving the expense of a pressure sensor and allowing for economical calculation of the auxiliary power cylinder pressure.

[0012] According to a preferred embodiment of the present invention, the arrival time of the measured auxiliary power cylinder pressure of the ESP pressure sensor is measured, and this arrival time is used to adjust the time delay between the virtual auxiliary power cylinder pressure and the measured auxiliary power cylinder pressure of the ESP pressure sensor. By calculating this arrival time, the time delay is determined, enabling a more accurate calculation of the pressure difference and thus the correlation model. This results in a more accurate determination of the virtual auxiliary power cylinder pressure, and thus improved control of the auxiliary power cylinder. The measurement of the arrival time is preferably performed regularly to ensure a continuously high level of accuracy.

[0013] According to another preferred embodiment of the present invention, the arrival time of a test signal is calculated to measure the time delay. Such a test signal may include a transmission time. By comparing the reception time with the transmission time, the arrival time can be calculated in a simple manner. This allows the arrival time to be measured in a simple manner independent of the braking operation, thereby increasing the accuracy of the calculated virtual auxiliary power cylinder pressure.

[0014] In a preferred embodiment, torque is used as the motor value for calculating the virtual auxiliary power cylinder pressure. In this case, the torque can be measured. Similarly, this value can be calculated in the control unit. This allows for a simple determination of the torque.

[0015] In a preferred embodiment, the motor current is used as the motor value for calculating the virtual auxiliary power cylinder pressure. Since the motor current is already known through the control unit, it is not necessary to determine this value. This allows the motor value to be determined in a simple manner.

[0016] The object of the present invention is further achieved by an apparatus for carrying out this method. The apparatus includes an auxiliary power cylinder, via which an auxiliary power cylinder pressure can be generated by an auxiliary power cylinder motor, an ESP pressure sensor, via which a time-delayed auxiliary power cylinder pressure can be measured, and a control unit, in which a virtual auxiliary power cylinder pressure can be calculated using a correlation model between the motor value and the virtual auxiliary power cylinder pressure. Through this calculation of the auxiliary power cylinder pressure, it is possible to provide auxiliary power cylinder pressure measurement without a pressure sensor. Therefore, such an apparatus achieves the advantages listed in the above method. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing an embodiment of an auxiliary power brake system for which the auxiliary power cylinder pressure is to be calculated according to the method of the present invention; [Figure 2] FIG. 1 illustrates an embodiment of a method for calculating an auxiliary power cylinder pressure of an auxiliary power brake system. [Figure 3] FIG. 1 illustrates an embodiment of a method for determining a time delay. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the invention is shown in the drawings and is explained in more detail below.

[0019] FIG. 1 shows an embodiment of an auxiliary power brake system 1 for calculating an auxiliary power cylinder pressure according to the method of the present invention. In this case, the auxiliary power brake system 1 includes two units 4 and 8. The first unit 4 is a substantially known auxiliary power system. Therefore, a detailed description will be omitted, and only the components relevant to the present invention will be described in detail. The first unit 4 includes an auxiliary power brake pressure generator 12 with an auxiliary power cylinder 16. The auxiliary power brake pressure generator 12 can generate an auxiliary power cylinder pressure via an auxiliary power cylinder motor 20 by moving an auxiliary power piston 24. The auxiliary power cylinder motor 20 is connected to a control unit 28, which controls the motor 20. In this case, the auxiliary power cylinder pressure is generated at a location X. In the prior art, an auxiliary power cylinder pressure sensor is typically located at location X to calculate the auxiliary power cylinder pressure. However, in this auxiliary power brake system 1, the auxiliary power cylinder pressure is calculated without using the auxiliary power cylinder pressure sensor.

[0020] The second unit 8 is in this example an ESP brake system, via which brake pressure can be applied to the wheel brakes 32. For measuring the brake pressure in the ESP brake system 8, an ESP pressure sensor 36 is arranged, which is likewise connected to the control unit 28 for transmitting the pressure to this. The rest of the ESP brake system 8 is constructed in a known manner, so a detailed description thereof will not be given.

[0021] 2 shows an embodiment of a method for calculating the auxiliary power cylinder pressure of the auxiliary power brake device 1 shown in FIG. 1. In a first step A, the motor value of the auxiliary power cylinder motor 20 is calculated. In this case, in this embodiment, the torque M M is calculated. This value is calculated in the standard way, so no additional sensor is needed for this. Optionally, the motor current of the auxiliary power cylinder motor 20 can also be calculated. Torque M M In the second step B, the hypothetical auxiliary power cylinder pressure p is calculated based on F For this purpose, the virtual auxiliary power cylinder pressure p F and torque M M The correlation between p F (M M ) is used. This correlation p F (M M ) may be values ​​such as the transmission characteristics of the auxiliary power cylinder motor 20, the resilience and piston area of ​​the brake system, etc.

[0022] The hypothetical auxiliary power cylinder pressure p calculated in this manner F is used for the auxiliary power cylinder control R, so that a separate pressure sensor can be omitted. In a third step C, the pressure of the ESP pressure sensor 36 is calculated. The pressure of the ESP pressure sensor 36 is transmitted to the control unit 28. In this control unit 28, in a fourth step D, the calculated auxiliary power cylinder pressure p F is the auxiliary power cylinder pressure p of the ESP pressure sensor 36 ESP The auxiliary power cylinder pressure p of the ESP sensor 36 is compared with ESP is transmitted to the control unit 28 after a delay and processed, the auxiliary power cylinder pressure p ESP is the calculated virtual auxiliary power cylinder pressure p F Time delay t v When comparing the two values, the auxiliary power cylinder pressure p ESP For this time delay t v is taken into consideration.

[0023] In the fifth step E, when comparing the detected deviation Δp between the two values, the correlation p F (M M ) is adjusted according to the deviation Δp, and the virtual auxiliary power cylinder pressure p F This newly records the calculated virtual auxiliary power cylinder pressure p F The accuracy can be improved.

[0024] Figure 3 shows the time delay t v 1 shows an embodiment of a method for determining the time delay t. For this purpose, in a first determination step M, a test signal is applied between the control unit and the ESP pressure sensor. In a second determination step N, the arrival time of the test signal is measured. From this arrival time, the time delay t v This value can then be updated in the manner shown in Figure 2. The time delay t v The corrected value of allows for greater precision when comparing the two, resulting in a more accurate correlation p F (M M ) can be calculated. [Explanation of symbols]

[0025] 1 Auxiliary power brake device 4 units, 1st unit 8 units, second unit, ESP brake system 12 Auxiliary power brake pressure generator 16 Auxiliary power cylinder 20 Auxiliary power cylinder motor 24 Auxiliary power piston 28 Control Unit 32 Wheel brake 36 ESP pressure sensor A. First Step B. Second Step C. Third Step D. Fourth Step E. Fifth Step p ESP ESP pressure sensor 36 auxiliary power cylinder pressure pF Auxiliary power cylinder pressure p F (M M ) Correlation, correlation model R Auxiliary power cylinder control t v Time Delay M First decision stage N Second decision stage M M Motor value, torque X places Δp deviation

Claims

1. Auxiliary power cylinder pressure (p Ｆ ) in a method for calculating At least one motor value (M Ｍ (A) calculating The motor value (M Ｍ ) and the virtual auxiliary power cylinder pressure (p Ｆ ) correlation model (p Ｆ (M Ｍ )) to calculate the motor value (M Ｍ ) to the virtual auxiliary power cylinder pressure (p Ｆ (B) calculating The auxiliary power cylinder pressure (p ＥＳＰ (C) calculating The virtual auxiliary power cylinder pressure (p Ｆ ) and the auxiliary power cylinder pressure (p ＥＳＰ ) the time delay (t ｖ ) and the virtual auxiliary power cylinder pressure (p Ｆ ) to the auxiliary power cylinder pressure (p ＥＳＰ ) and step (D) of comparing The correlation model (p) is calculated according to the calculated deviation (Δp). Ｆ (M Ｍ (E) modifying The auxiliary power cylinder pressure (p Ｆ ) method for calculating

2. The measured auxiliary power cylinder pressure (p ＥＳＰ ) arrival time is measured, and the arrival time is used to calculate the virtual auxiliary power cylinder pressure (p Ｆ ) and the measured auxiliary power cylinder pressure (p ＥＳＰ ) between the time delay (t ｖ 2. The method of claim 1, wherein the temperature is adjusted by adjusting the temperature.

3. The time delay (t ｖ 3. The method of claim 2, further comprising calculating the arrival time of the test signal to measure the time of arrival of the test signal.

4. The virtual auxiliary power cylinder pressure (p Ｆ ) to calculate the motor value (M Ｍ 4. The method according to claim 1, wherein torque is used as the force.

5. The virtual auxiliary power cylinder pressure (p Ｆ 4. The method according to claim 1, wherein the motor current is used as the motor value for calculating the motor speed.

6. 6. An apparatus for carrying out the method according to any one of claims 1 to 5, The system has an auxiliary power cylinder (16), and an auxiliary power cylinder pressure can be generated by an auxiliary power cylinder motor (20) via the auxiliary power cylinder (16); The auxiliary power cylinder pressure (p ＥＳＰ ) time-delayed pressure can be measured, A control unit (28) is provided, and the control unit (28) controls a virtual auxiliary power cylinder pressure (p Ｆ ) is the motor value (M Ｍ ) and the virtual auxiliary power cylinder pressure (p Ｆ ) correlation model (p Ｆ (M Ｍ )) can be calculated using Apparatus for carrying out the method according to any one of claims 1 to 5.

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