Method for powering / operating power brake device by electric fluid pressure

Abstract

To energize a power brake pressure generator only when a change of a target value (pSoll) is greater than a predetermined deviation (Δp) in order to conserve power in a power saving mode for a power vehicle brake device by electric fluid pressure.SOLUTION: In the method, a power brake device has a power brake pressure generator comprising an electric mechanical drive part, the power brake pressure generator to generate brake pressure by depending on a target value (pSoll) set by a vehicle driver. In order to conserve electric energy, the electric mechanical drive part of the brake pressure generator is energized only when a change of the target value (pSoll) is greater than a predetermined deviation (Δp).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for power-operating an electrohydraulic power brake device for a powered vehicle, comprising the configuration of the prerequisite part of claim 1. [Background technology]

[0002] Patent Document 1 discloses an electrohydraulic power brake system for an automobile, comprising a brake master cylinder operable by muscle force and an electrohydraulic power brake pressure generator. The electrohydraulic power brake pressure generator has a piston-cylinder unit, the piston of which is displaceable within the cylinder of the piston-cylinder unit via a screw drive mechanism by an electric motor to generate brake pressure. For redundancy, this known brake system has two power supply mechanisms for the electric motor of the power brake pressure generator. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] German Patent Application Publication No. 102016201047A1 Specification [Overview of the project]

[0004] The present invention relates to a method for power-operating an electrohydraulic power brake system for a powered vehicle in an energy-saving mode, having the configuration of claim 1. "Power operation" means generating brake pressure hydraulically using a power-operated brake pressure generator to operate one or more hydraulic wheel brakes connected to the brake system. The power-operated brake pressure generator has an electromechanical drive unit, particularly equipped with an electric motor. "Energy-saving mode" means an operating mode of the brake system that conserves electrical energy.

[0005] To conserve electrical energy in power-saving mode, the present invention proposes energizing the electromechanical drive unit of a power-driven brake pressure generator only when the target value for brake pressure changes by more than a predetermined deviation. If the target value for brake pressure changes by less than or equal to the predetermined deviation, the electromechanical drive unit of the power-driven brake pressure generator is not energized, thereby saving current.

[0006] The target brake pressure is generated, in particular, by a brake master cylinder that can be operated by muscle force, a foot brake pedal, or a hand brake lever operated by the vehicle driver. The target value can be determined, for example, by measuring the hydraulic pressure generated in the brake master cylinder, or by measuring the brake master cylinder piston stroke, foot brake pedal stroke, or hand brake lever stroke, and estimating the value. Generally speaking, the target value is set by the vehicle driver, particularly by operating the brake master cylinder, or by the movement of the foot brake pedal or hand brake lever, in which case other means of setting the target value are also possible.

[0007] If a vehicle driver wants to increase or decrease the target value for brake pressure, that is, if the vehicle driver wants to increase or decrease the braking force, according to the present invention, in power-saving mode, the electromechanical drive unit of the power-type brake pressure generator is not immediately energized, but is only energized when the target value changes by more than a predetermined deviation. If the vehicle driver changes the target value (any number of times) within the predetermined deviation, the electromechanical drive unit of the power-type brake pressure generator is not energized, thereby saving electrical energy. Of course, in this case, the brake pressure and therefore the braking force do not change.

[0008] Preferably, the brake device is operated in the power-saving mode according to the present invention only in exceptional cases, for example, when the emergency power supply mechanism is used to activate the brake device in the event of a failure of the main power supply mechanism or a failure of one of the multiple power supply mechanisms. When the power supply is normal, the brake device is preferably operated in the standard mode, that is, the electromechanical drive unit of the power-driven brake pressure generator is energized so that the brake pressure in the brake device changes in accordance with the target value each time the target value changes.

[0009] The present invention proposes operating the brake system in energy-saving mode only when the brake system is already operated and the minimum pressure is dominant. If the brake system is not operated and there is no pressure, the electromechanical drive unit of the powered brake pressure generator is energized until the minimum pressure is reached or exceeded, causing the powered brake pressure generator to generate a target brake pressure set by the vehicle driver. This ensures that the brake system is operated immediately using the powered brake pressure generator when the vehicle driver requests braking, rather than only being operated when the target value exceeds a predetermined deviation.

[0010] The dependent claims cover further and advantageous features of the invention described in the independent claims.

[0011] All constituent elements disclosed herein and in the drawings may be realized individually or in essentially any combination in embodiments of the invention. Embodiments of the invention may essentially have only one or some of the constituent elements of one claim or one embodiment of the invention, rather than having all of them.

[0012] Next, the present invention will be described in more detail using one embodiment illustrated in the drawings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of an electrohydraulic power brake device for carrying out the method according to the present invention. [Figure 2] It is a graph of the pressure change of the brake pressure in the brake device of FIG. 1 when implementing the method according to the present invention.

Embodiments for Implementing the Invention

[0014] The electro-hydraulic power brake device 1 shown in FIG. 1 is provided for a motor vehicle, that is, for an automobile. The power brake device has a brake master cylinder 2 operable by muscular force, a power brake pressure generator 3, a slip control unit 4, and hydraulic wheel brakes 5. In this embodiment, the brake device 1 is a two-circuit type brake device 1, and the brake master cylinder 2 is a two-circuit type brake master cylinder 2. The brake device has four wheel brakes 5, and two of them are respectively assigned to one brake circuit. The number of wheel brakes 5, its assignment to the brake circuit, and the number of brake circuits are not mandatory for the present invention.

[0015] The wheel brakes 5 are connected to the slip control unit 4, and the slip control unit 4 is connected to the brake master cylinder 2 by a shut-off valve 6 in each brake circuit.

[0016] The power brake pressure generator 3 is provided to generate a hydraulic brake pressure using power. The power brake pressure generator is hydraulically connected in parallel to the brake master cylinder 2 in each brake circuit by a power valve 7. The power brake pressure generator 3 has a piston-cylinder unit 8 with a piston 9, and the piston is displaceable in the cylinder 12 via a screw transmission mechanism 11 using an electric motor 10 to generate a brake pressure with power. The electric motor 10 and the screw transmission mechanism 11 form the electromechanical drive unit 13 of the power brake pressure generator 3. A reduction transmission mechanism (not shown) may be arranged between the electric motor 10 and the screw transmission mechanism 11.

[0017] The slip control unit 4 is connected to the brake master cylinder 2 by a shut-off valve 6 and to the power brake pressure generator 3 by a power valve 7, precisely to the cylinder 12 of the piston-cylinder unit 8 of the power brake pressure generator 3.

[0018] The slip control unit 4 has one hydraulic pump 14 in each brake circuit, and the plurality of hydraulic pumps can all be driven using one electric motor 15 and are also called reverse pumps. Furthermore, the slip control unit 4 has a suction valve 16 and a discharge valve 17 for controlling the wheel brake pressure for each wheel brake 5, and the suction valve and the discharge valve are symbolically illustrated in FIG. 1 using the circuit symbols 16, 17. The slip control may have further valves, hydroaccumulators, further hydraulic components. Abbreviations such as ABS, ASR, FDR are customary for slip controls such as antilock control, antispin regulation, dynamic drive control and are well-known and not explained here.

[0019] Service braking is performed as power braking, where brake pressure is generated by power using a power-driven brake pressure generator 3 and controlled using the power-driven brake pressure generator 3 and / or the suction valve 16 and discharge valve 17 of the slip control unit 4. In the case of service braking, the power-driven brake pressure generator 3 is coupled to the brake circuit of the brake device 1 by opening the power valve 7, and the brake master cylinder 2 is hydraulically disconnected from the power-driven brake pressure generator 3 and the slip control unit 4 by closing the gate valve 6. The brake master cylinder 2 is used as a target value setter for the brake pressure to be generated using the power-driven brake pressure generator 3. For this purpose, a pressure sensor 18 is connected to the brake master cylinder 2. For redundancy, a pedal stroke sensor 19 is located on the foot brake pedal 20 that can operate the brake master cylinder 2. The pedal stroke sensor 19 similarly forms a target value setter for the brake pressure to be generated using the power-driven brake pressure generator 3.

[0020] In order to remove brake fluid from the brake master cylinder 2 when the gate valve 6 is closed, displace the brake master cylinder piston within the brake master cylinder 2, and move the foot brake pedal 20, a pedal stroke simulator 21 is connected to the brake master cylinder 2 by a simulator valve 22 within one brake circuit. The pedal stroke simulator 21 has a piston-cylinder unit with a piston that is biased by spring pressure or gas pressure.

[0021] In the event of a failure of the powered brake pressure generator 3, the brake system 1 can be operated by muscle power using the brake master cylinder 2. Emergency braking is possible using the hydro pump 14 of the slip control unit 4.

[0022] In this embodiment, the gate valve 6 and the suction valve 16 are 2-port, 2-position solenoid valves that are open in their current-free basic position, while the power valve 7 and the discharge valve 17 are 2-port, 2-position solenoid valves that are closed in their current-free basic position.

[0023] For redundancy purposes, in this embodiment, the brake device 1 has two batteries or accumulators as power supply mechanisms 23 and 24. In this configuration, the motor 10 of the powered brake pressure generator 3 is connected to one power supply mechanism 23, and the motor 15 of the slip control unit 4 is connected to the other power supply mechanism 24. The motor 10 of the powered brake pressure generator 3 can also be operated using the power supply mechanism 24 of the slip control unit 4.

[0024] If the power supply mechanism 23 of the powered brake pressure generator 3 fails, the powered brake pressure generator 3 is operated using the power supply mechanism 24 of the slip control unit 4. That is, the electric motor 10 of the piston / cylinder unit 8 of the powered brake pressure generator 3 is powered from the power supply mechanism 24 of the slip control unit 4, and the brake device 1 operates in the power-saving mode according to the present invention. This power-saving mode is illustrated by the graph in Figure 2 as an example. There, a curve or straight line p Soll The curve or straight line p indicates the target value for the brake pressure to be generated using the powered brake pressure generator 3. Fremd This shows the brake pressure generated using the powered brake pressure generator 3.

[0025] When the brake master cylinder 2 is not operated and the brake device 1 is unpressured, pressing the foot brake pedal 20 operates the brake master cylinder 2, and the powered brake pressure generator 3 generates brake pressure p Fremd target value p Soll It is generated depending on [something]. Target value p Soll This depends on the brake master cylinder pressure measured using the pressure sensor 18, or the stroke of the foot brake pedal 20 or the stroke of the primary piston of the brake master cylinder 2 measured using the pedal stroke sensor 19.

[0026] If the foot brake pedal 20 is not moved when the brake master cylinder 2 is operated, the brake pressure p generated by using the power brake pressure generator 3 Fremd reaches the target value p Soll At this time, the energization of the electric motor 10 of the power brake pressure generator 3 is terminated. This is the time interval between time points t1 and t2 in FIG. 2. The foot brake pedal 20 is moved again, and if the brake pressure p Soll in the brake master cylinder 2 rises or falls, the electric motor 10 of the power brake pressure generator 3 is energized only when the change is greater than a predetermined deviation Δp. The deviation Δp may be an absolute value or a relative value depending on the current brake pressure. FIG. 2 shows that the target value p Soll rises during the time interval t2 to t3, and the target value p Soll falls during the time interval t3 to t4, and at this time the change in the target value p Soll is smaller than the predetermined deviation Δp. Therefore, in the power saving mode according to the present invention, the electric motor 10 of the power brake pressure generator 3 is not energized, and the brake pressure p Fremd generated by the power brake pressure generator 3 remains constant. ..

[0027] In the present embodiment, in FIG. 2, starting from time point t4, the target value p Soll is increased again. At this time, after time point t5, the deviation is greater than the predetermined deviation Δp. Therefore, from this time on, the electric motor 10 of the power brake pressure generator 3 is energized again, and as a result, the power brake pressure generator 3 increases the brake pressure p Fremd again. If, instead of increasing the target value p Soll the target value p Soll is decreased, and as a result the change in the target value p Soll is greater than the predetermined deviation Δp, the electric motor 10 of the power brake pressure generator 3 is similarly energized again from this time, but in the reverse rotation direction, and as a result, the brake pressure p Fremd generated by the power brake pressure generator 3 decreases.

[0028] Power saving in the power saving mode according to the present invention is achieved with a target value p Soll The effect is particularly large if the value is frequently changed within a predetermined deviation of Δp or less.

[0029] Therefore, the brake master cylinder 2, which had not been operated, is operated, and the powered brake pressure generator 3 generates brake pressure p Fremd The same process is generated, and only after deceleration exceeds a predetermined deviation Δp does the brake pressure p occur. Fremd If this does not occur, in the unpressurized brake device 1, when the brake master cylinder 2 is operated, the electric motor 10 of the powered brake pressure generator 3 is energized in the same way, and the brake pressure, in this embodiment, will reach the target value p Soll However, minimum pressure p min Use power saving mode only when the value is greater than [a certain value]. [Explanation of Symbols]

[0030] 1. Power braking system 2. Brake Master Cylinder 3. Powered brake pressure generator 5 Wheel brakes 7 Power valve 13 Electromechanical drive unit 23,24 Power supply mechanism p Brake pressure p min Minimum pressure p Soll Target value Δp predetermined deviation

Claims

1. A method for power operating in a power saving mode an electrohydraulic power brake system (1) for a motor vehicle, the power brake system having a powered brake pressure generator (3) with an electromechanical drive (13), the powered brake pressure generator controlling a target value (p Ｓｏｌｌ In the method for generating brake pressure depending on the target value (p Ｓｏｌｌ ) changes by more than a predetermined deviation (Δp), the electromechanical drive (13) of the powered brake pressure generator (3) being energized.

2. The brake pressure (p) is the minimum pressure (p ｍｉｎ ), and actuating the powered brake pressure generator (3) immediately from the onset of a driver braking request without deviation from the target value in order to increase the brake pressure during non-operation of the power brake device (1).

3. 3. The method according to claim 1 or 2, characterized in that the deviation (Δp) is absolute or dependent on the brake pressure.

4. The power brake device (1) has a brake master cylinder (2) that can be operated by muscle force, and the brake master cylinder sets the target value (p Ｓｏｌｌ 3. The method according to claim 1, further comprising generating a signal of:

5. 3. The method according to claim 1 or 2, characterized in that the power brake device (1) has a power valve (7) by means of which the power brake pressure generator (3) can be hydraulically decoupled from the wheel brakes (5) of the power brake device (1), and in that the power valve (7) is closed when the electromechanical drive (13) of the power brake pressure generator (3) is de-energized in the power saving mode.

6. 3. The method according to claim 1 or 2, characterized in that the power brake device (1) has two power supplies (23, 24) and the method is carried out when one of the power supplies (23) fails.

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