A method for testing the contact between the mutually coupled circuit branches of the separate braking circuits in an electronically adjustable power-assisted braking system of a motor vehicle.

Abstract

The present invention relates, particularly to a method for verifying the conformal pressure medium conductive contact of mutually subordinate circuit branches (C1.1, C1.2; C2.1, C2.2) of separate brake circuits (C1; C2) of an electronically adjustable power-assisted braking system for motor vehicles, the power-assisted braking system having two actuator units (DPB; ESP) in pressure medium conductive contact for brake pressure generation and brake pressure regulation; and an electronic controller (ECU) for performing the method in a further configuration for such power-assisted braking systems.

Description

Technical Field

[0001] The present invention relates to a method, particularly for motor vehicles, for verifying the conformal pressure medium conduction contact of mutually subordinate circuit branches of a power-assisted braking system capable of electronic slip adjustment, according to the features of claim 1, the power-assisted braking system having two actuator units in pressure medium conduction contact for brake pressure generation and brake pressure regulation, and an electronic controller further configured according to the features of claim 4 for performing the above method. Background Technology

[0002] Power-assisted braking systems are prior art and are disclosed, for example, in DE 102018202884 A1.

[0003] Figure 1 A hydraulic layout diagram of the power-assisted braking system upon which this invention is based is shown. For safety reasons, the power-assisted braking system is divided into two separate braking circuits (C1; C2). It includes two separate actuator units (DPB; ESP), which are in contact with each other conductively via two connecting lines. The two actuator units (DPB, ESP) are connected in parallel to the two braking circuits (C1; C2). The first actuator unit (DPB) further includes a driver-operable device (BRU) for detecting braking desire, a first brake pressure generator (PLU) that can be powered, and control valves (CSV1, CSV2; PSV1, PSV2; POV; SSV) for generating and regulating the braking pressure to meet the braking desire.

[0004] The second actuator unit (ESP) is equipped with a second brake pressure generator (RFP1; RFP2) and control valves (IV1-4; OV1-4; SCC1; SCC2; HSR1, HSR2) that are also power-assisted and used for wheel-specific adjustment of brake pressure. Wheel brakes (WC1-WC4) connected to the second actuator unit (ESP) are subjected to braking pressure. These wheel brakes (WC1-WC4) are distributed to the two brake circuits (C1; C2) of the power-assisted braking system and are paired with corresponding axles of the vehicle, or as... Figure 1 The wheels (FL, RR, FR, RL) of a motor vehicle are arranged diagonally opposite each other.

[0005] Specifically, braking pressure is adjusted based on the slippage present at the wheels (FL, RR, FR, RL) of the motor vehicle. The vehicle braking system is equipped with an electronic control unit (ECU) that detects relevant measurement data from the power assist braking system and / or vehicle sensors and processes it into control signals. These control signals are then used to operate the pressure medium control components of the actuator unit (DPB; ESP). For this purpose, the pressure medium connection between the pressure medium control components of the power assist braking system is released, throttled, or blocked as needed by the control valves in the actuator unit (DPB; ESP).

[0006] In addition, the measurement data is provided by the pressure sensor (PS_AC) of the first actuator unit (DPB) and the pressure sensor (PS_MC2) of the second actuator unit (ESP). The first pressure sensor (PS_AC) detects the pressure provided by the first brake pressure generator (PLU), while the second pressure sensor (PS_MC2) measures the pressure in the second brake circuit (C2).

[0007] For completeness, it should be mentioned that the Brake Expectation Detection Unit (BRU) is also connected in parallel with the brake circuit (C1; C2), wherein the pressure medium connection is also controllably implemented by means of a control valve (CSV1; CSV2), which is therefore also called a circuit isolation valve.

[0008] In the special case of power steering failure, the driver can thus increase the braking pressure in the wheel brakes (WC1-WC4) by using muscle force to operate the master cylinder (MC) of the Brake Expectation Detection Unit (BRU) and thus brake the vehicle despite the lack of power steering support.

[0009] Under operating conditions, i.e., with power-assisted operation functioning correctly, the pressure medium connection between the master cylinder (MC) and the brake circuit (C1; C2) is interrupted by the circuit isolation valves (CSV1, CSV2), and the driver's brakes are engaged in a pressure-loadable simulator (PFS) to detect braking demand. The simulator control valve (SSV) controls the loading of the simulator (PFS). The simulator (PFS) simulates the operating stroke of the master cylinder (MC) for the driver and also simulates the operating force. A pedal travel sensor (PTS) is present in the first actuator unit (DPB) to detect the operating stroke. Therefore, under normal conditions of the power-assisted braking system, the driver is decoupled from the wheel brakes (WC1-WC4) and does not contribute to the increase in braking pressure.

[0010] As mentioned, the power-assisted braking system on which this invention is based has two actuator units (DPB; ESP) that are in contact with each other via lines that guide pressure media. This contact is achieved by ensuring that the circuit branches (C1.1; C1.2) of the first actuator unit (DPB) belonging to the braking circuit (C1; C2) are not vertauschted with the circuit branches (C2.1; C2.2) of the second actuator unit (ESP).

[0011] The main reason is that, due to structural space and cost considerations, not both braking circuits (C1; C2) are equipped with pressure sensors. Therefore, the reversed contact of the braking circuit branches (C1.1, C1.2; C2.1, C2.2) belonging to each other results in the fact that, due to the lack of existing adjustment parameters, the electronic control unit (ECU) cannot adjust the braking pressure at all or at least only within a limited range.

[0012] Because the installation of the power-assisted braking system in motor vehicles is not clear, it is not easy to identify by visual inspection whether the hydraulic contact of the circuit branches (C1.1, C1.2; C2.1, C2.2) is performed in accordance with regulations, or whether the circuit branches (C1.1, C1.2; C2.1, C2.2) are inadvertently reversed when the actuator unit (DPB; ESP) is activated. Summary of the Invention

[0013] Advantages of this invention: This invention proposes a method that allows for electrical verification of the contact of the braking circuit (C1; C2) in the installed state of the power-assisted braking device, ensuring that the contact meets the specified requirements.

[0014] The proposed method is robust relative to the manufacturing tolerances of the installed components of the power-assisted braking system, and therefore can reliably identify incorrectly connected braking circuits (C1; C2). To this end, the method utilizes components already present in the vehicle braking system, measurement signals, or existing signal paths, and thus can be easily and cost-effectively integrated into the control software of the vehicle braking system's electronic control unit (ECU).

[0015] Other advantages or advantageous modifications of the invention are derived from the dependent claims or the description below. Attached Figure Description

[0016] Embodiments of the present invention are shown in the accompanying drawings and are described in detail below.

[0017] The attached diagrams consist of a total of 3 images, among which, Figure 1The power-assisted braking system on which the present invention is based is shown, which is known in the prior art and has been evaluated at the beginning; Figure 2 It shows that according to Figure 1 The power-assisted braking system, but it has an inverted braking circuit; and Figure 3 The flowchart illustrates the method upon which this invention is based.

[0018] In the accompanying drawings, corresponding components are given the same reference numerals. Detailed Implementation

[0019] Figure 2 The power-assisted braking system shown corresponds to that according to Figure 1 The power-assisted braking system is characterized by an incorrect connection between the guide pressure medium in the corresponding circuit branches (C1.1, C1.2; C2.1, C2.2) of the actuator units (DPB; ESP). The error lies in the fact that the circuit branch (C1.1) of the first actuator unit (DPB) corresponding to the first braking circuit (C1) is in contact with the second circuit branch (C2.2) of the second actuator unit (ESP) corresponding to the second braking circuit (C2); and correspondingly, the second circuit branch (C1.2) of the first actuator unit (DPB) corresponding to the second braking circuit (C2) is connected with the circuit branch (C2.1) of the second actuator unit (ESP) corresponding to the first braking circuit (C1). In short, when the braking circuits (C1; C2) are in contact, the corresponding circuit branches (C1.1; C1.2 or C2.1; C2.2) are reversed.

[0020] This invention proposes a testing method that allows the electronic control unit (ECU) of the power-assisted braking system to check for such erroneous contact. Therefore, erroneous contact between the brake circuits (C1; C2) can still be detected after the power-assisted braking system is installed in the vehicle body, and can be reported to the driver, mechanic, or assembler via appropriate warning indicators when necessary. Warning indicators can be, for example, optical signals on a display and / or acoustic signals from a speaker. For this purpose, vehicle-side displays or speakers can also be used, such as those of a testing device coupled to the electronic control unit (ECU) for performing the test.

[0021] To better understand the testing method according to the present invention, it is first described in detail below. Figure 2 The diagram shows the layout of the power-assisted braking system.

[0022] The first actuator unit (DPB) of the power-assisted braking system includes a brake expectation detection unit (BRU) through which the driver can preset braking expectations. For this purpose, the brake expectation detection unit consists of a master brake cylinder (MC), which can be operated by means of a control element, for example, a pedal (P). The master brake cylinder (MC) has a directly actuated connecting rod piston (MC1) and an indirectly actuated floating piston (MC2), wherein two master cylinder chambers (MC1'; MC2') are formed either between the connecting rod piston (MC1) and the floating piston (MC2) or between the floating piston (MC2) and the master brake cylinder housing. Each master brake cylinder chamber (MC1'; MC2') is connected to one of the two brake circuits (C1; C2) of the power-assisted braking system.

[0023] Braking expectation is derived from the measured travel of the pedal (P). To this end, a so-called pedal travel sensor (PTS) is present in the first actuator unit (DPB), which converts the travel of the pedal (P) into a voltage signal and transmits the voltage signal to the electronic control unit (ECU).

[0024] In the normal state of the power-assisted braking system, the master brake cylinder (MC) is decoupled from the wheel brakes (WC1-WC4) of the brake circuit (C1; C2), meaning the pressure medium connection between the master brake cylinder (MC) and the brake circuits (C1; C2) of the wheel brakes (WC1-WC4) with corresponding connections is interrupted. This is performed by a first control valve device consisting of two so-called circuit isolation valves (CSV1, CSV2), which, once electrically operated, disconnect these connections; or, when no electrical operation occurs, open these connections. In the illustrated embodiment, the circuit isolation valves (CSV1; CSV2) are exemplary implemented as normally open 2 / 2-way switching valves.

[0025] To allow for pedal (P) actuation and provide mechanical reaction to the driver even when the circuit isolation valves (CSV1; CSV2) are closed, one of the chambers (MC1') of the master brake cylinder (MC) is coupled to a simulator (PFS). This simulator is a piston-cylinder assembly capable of loading pressure media from the connected chamber (MC1') of the master brake cylinder (MC). When pressure media is loaded, the piston moves within the cylinder against the force of the elastic return element. The pressure media connection between the simulator (PFS) and the master brake cylinder (MC) is controlled by a simulator control valve (SSV). The simulator control valve (SSV) shown is an electrically operated, normally closed 2 / 2-way switching valve.

[0026] In addition to the components already described, the first actuator unit (DPB) also includes a first brake pressure generator (PLU). The latter is implemented as a plunger unit and correspondingly equipped with a plunger piston housed in a plunger cylinder in a manner movable by a first electrically controllable motor (M1). The working space of the plunger unit is supplied with pressure medium by a reservoir (RSV), to which the master cylinder chambers (MC1'; MC2') of the master brake cylinder (MC) of the power-assisted braking system are also connected. The pressure medium supply to the plunger unit or the first brake pressure generator (PLU) can be controlled by an electrically controllable plunger supply valve (POV), which is, for example, configured as a normally closed 2 / 2-way switching valve.

[0027] The first brake pressure generator (PLU) supplies a pressure medium at braking pressure to two circuit branches (C1.1; C1.2) of the first actuator unit (DPB). This braking pressure is detectable by a first pressure sensor (PS_AC) and transmitted as an electrical signal (PS_AC') to the controller (ECU). For this purpose, the first pressure sensor (PS_AC) is located in a piping section of the first actuator unit (DPB) connecting the outlet of the first brake pressure generator (PLU) to two control valves called plunger isolation valves (PSV1; PSV2). Each brake circuit (C1; C2) is equipped with plunger control valves (PSV1, PSV2), whose function is to isolate the first brake pressure generator (PLU) from its corresponding brake circuit (C1; C2). Therefore, the plunger isolation valves (PSV1; PSV2) are electrically operable and normally shut-off 2 / 2-way switching valves.

[0028] Corresponding to the first actuator unit (DPB), the second actuator unit (ESP) is also equipped with electrically operable control valves (HSR; SCC; IV1-IV4; OV1-OV4) and a pressure generator, which will be referred to as the second pressure generator below for distinction. The second pressure generator has one pump for each brake circuit (C1; C2) of the second actuator unit (ESP), i.e., a total of two pumps (RFP1; RFP2), which can be jointly operated by the second drive motor (M2). The suction side of each of these pumps (RFP1; RFP2) of the second pressure generator is correspondingly connected to the accumulator (RSV) of the power-assisted braking system via allocated suction lines (SL1; SL2). Each suction line (SL1; SL2) contains a spring-loaded check valve that releases the pressure medium flow from the reservoir (RSV) to the pump (RFP1; RFP2) and blocks the flow back from the pump (RFP1; RFP2) to the reservoir (RSV).

[0029] The circuit isolation valves (CSV1; CSV2) and plunger control valves (PSV1; PSV2) of the first actuator unit (DPB) are connected in pairs to one of these suction lines (SL1; SL2) on the outflow side. Furthermore, suction valves (HSR1; HSR2) are positioned directly upstream of the pumps (RFP1; RFP2) of the second pressure generator in the second actuator unit (ESP) within the allocated suction lines (SL1; SL2). Thus, together with the pressure regulating valves (SCC1; SCC2) on the pressure side of each pump (RPP1; RPP2), the braking pressure supplied by the pumps (RFP1; RFP2) of the second pressure generator in each braking circuit (C1; C2) can be regulated. Therefore, the suction valves (HSR1; HSR2) are electrically operable, normally closed 2 / 2-way switching valves, while the pressure regulating valves (SCC1; SCCV2) are normally open 2 / 2-way regulating valves, and check valves that open in the direction of the wheel brakes (WC1-WC4) are connected in parallel accordingly.

[0030] The braking pressure in the second braking circuit (C2) is detected by the second pressure measuring device in the second actuator unit (ESP), namely the so-called loop pressure sensor (PS_MC2), converted into a voltage signal (PS_MC2') and transmitted to the electronic controller (ECU) for evaluation.

[0031] Finally, each wheel brake (WC1-WC4) is also equipped with a valve pair consisting of a pressure boosting valve (IV1-IV4) and a pressure reducing valve (OV1-OV4), respectively, to allow for individualized pressure adjustment of the corresponding wheel brake (WC1-WC4). The pressure boosting valves (IV1-IV4) are electrically operated, normally open 2 / 2-way regulating valves, while the pressure reducing valves (OV1-OV4) are normally closed 2 / 2-way switching valves. The pressure reducing valves (OV1-OV4) are located in the return line (RL1; RL2) on the suction side of the pump (RFP1; RFP2) associated with the second brake pressure generator (ESP) from the corresponding wheel brake (WC1-WC4). In this return line, for each brake circuit (C1; C2), there is a so-called low-pressure reservoir (ACC1; ACC2), which first buffers the pressure medium released from the wheel brakes (WC1-WC4) until it is drawn out again by the associated pump (RFP1; RFP2) to increase the braking pressure.

[0032] As already mentioned, the two braking circuits (C1; C2) are in reverse contact between the two actuator units (DPB; ESP), that is, the braking circuit branch (C1.1) of the first actuator unit (DPB) is connected to the second braking circuit branch (C2.2) of the second actuator unit (ESP), while the second braking circuit branch (C1.2) of the first actuator unit (DPB) is connected to the first braking circuit branch (C2.1) of the second actuator unit (ESP). This type of error can be exploited by the electronic control unit (ECU). Figure 3 The determination is made according to the test method shown in the flowchart and described below: After the test method begins (S), the plunger supply valve (POV) is closed in the first step (S1), thus interrupting the pressure medium connection between the first brake pressure generator (PLU) and the reservoir (RSV).

[0033] In the next step (S2), the two circuit isolation valves (CSV1; CSV2) of the first actuator unit (DPB) are electrically operated so that they enter their blocking position, and thus decouple the master brake cylinder (MC) from the brake circuit (C1; C2).

[0034] In the layout shown in the figure, the circuit isolation valves (CSV1; CSV2) are energized for this purpose, and the plunger supply valve (POV) is not energized.

[0035] Now, in step 3 (S3), the plunger isolation valve (PSV1) of the first loop branch (C1.1) of the first actuator unit (DPB) is closed, and the plunger isolation valve (PSV2) of the second loop branch (C1.2) is opened, and then the first brake pressure generator (PLU) is operated. When the loop branches (C1.1, C1.2; C2.1, C2.2) are properly engaged, the loop branch (C1.2) released by the plunger control valve (PSV2) is connected to the loop branch (C2.2), that is, the loop branch where the second pressure sensor (PS_MC2) is located.

[0036] The increase in braking pressure caused by the operation of the first braking pressure generator (PLU) is detected by the first pressure sensor (PS_AC) of the first actuator unit (DPB), and the corresponding signal (PS_AC') is forwarded to the electronic controller (ECU). In addition, the signal (PS_MC2') from the loop pressure sensor (PS_MC2) is sent to the electronic controller (ECU) (step 4).

[0037] Next, in step S5 (ECU), the electronic controller (ECU) performs a signal comparison to determine whether there is any correlation or lack thereof between the input signals (PS_AC'; PS_MC2').

[0038] When the loop branches (C1.1, C1.2; C2.1, C2.2) are connected in reverse to the actuator unit (DPB; ESP), and because the loop branch (C2.2) is thus not supplied with pressure medium from the first brake pressure generator (PLU) due to the closure of the plunger isolation valve (PSV1), no parallel pressure increase occurs at the loop pressure sensor (PS_MC2) of the second actuator unit (ESP). Therefore, the signals (PS_AC'; PS_MC2') received at the electronic controller (ECU) are very different from each other or uncorrelated. In the case of comparing signals, uncorrelated measurement signals are easily identified and interpreted as erroneous contact of the loop branches (C11, C1.2; C2.1, C2.2). In the event of an error, the electronic controller (ECU) then prompts the issuance of a corresponding warning indication and then terminates the method.

[0039] If the loop branches (C1.1, C1.2; C2.1, C2.2) are based on Figure 1 The diagram shows that when connected to the actuator units (DPB, ESP) as specified, a corresponding pressure increase occurs on the second pressure sensor (PS_MC2) of the second actuator unit (ESP) in parallel with a pressure increase on the first pressure sensor (PS_AC) of the first actuator unit (DPB), and the signals (PS_AC'; PS_MC2') reaching the electronic controller (ECU) are at least largely corresponding to or correlated with each other. Therefore, the electronic controller (ECU) infers that the braking circuit (C1; C2) has correctly implemented contact and terminates the method by preventing the output of a warning signal.

[0040] Of course, variations or advantageous modifications of the described method can be envisioned without departing from the scope of protection defined by the features of independent claims 1 and 4.

Claims

1. A method for inspecting the contact of mutually associated circuit branches (C1.1, C1.2; C2.1, C2.2) of separate brake circuits (C1; C2) of an electronically slip-adjustable power-assisted braking system of a motor vehicle, said power-assisted braking system having two actuator units (DPB; ESP) in pressure-medium conductive contact for brake pressure generation and brake pressure regulation. wherein The power-assisted braking system has: A driver-operable device (BRU) for detecting braking expectations. The first actuator unit (DPB) controllably drives a first brake pressure generator (PLU) for generating brake pressure in the brake circuit (C1; C2). A plunger supply valve (POV) is used to control the first pressure medium connection between the first brake pressure generator (PLU) and the pressure medium reservoir (RSV). The first pressure sensor (PS_AC) is used to detect the pressure provided by the first brake pressure generator (PLU). The second actuator unit (ESP) has a controllably driveable second brake pressure generator (RFP1; RFP2) for wheel-specific adjustment of the brake pressure in the wheel brakes (WC1-WC4) of the brake circuit (C1; C2). The second pressure sensor (PS_MC2) is used to detect the pressure in one of the braking circuits (C2). Circuit isolation valves (CSV1; CSV2) are used to control the pressure medium connection from the master brake cylinder (MC) to the brake circuit (C1; C2). Piston isolation valves (PSV1; PSV2) are used to control the pressure medium connection from the first brake pressure generator (PLU) to the brake circuit (C1; C2), and An electronic controller (ECU) detects signals (PC_AC', PS_MC2') from sensors (PS_AC, PS_MC2) and further processes them into electrical control signals for the pressure generator (PLU; RFP1, RFP2) and valve devices (POV, CSV1, CSV2; PSV1, PSV2). Its features are, Step S1: The electronic control unit (ECU) interrupts the pressure medium connection between the first brake pressure generator (PLU) and the pressure medium reservoir (RSV) by correspondingly manipulating the plunger supply valve (POV). Step S2: The electronic control unit (ECU) interrupts the pressure medium connection from the master brake cylinder (MC) to the brake circuit (C1, C2) by correspondingly manipulating the circuit isolation valves (CSV1; CSV2). Step S3: The electronic control unit (ECU) opens the pressure medium connection between the first brake pressure generator (PLU) and the brake circuit (C2) equipped with the second pressure sensor (PS_MC2) by correspondingly operating the plunger isolation valves (PSV1, PSV2), and disconnects the corresponding pressure medium connection between the first brake pressure generator (PLU) and the corresponding other brake circuit (C1). Step S4: The electronic control unit (ECU) generates braking pressure by manipulating the first brake pressure generator (PLU), the braking pressure being detected by the first pressure sensor (PS_AC) and transmitted to the electronic control unit (ECU). Step S5: If the signal (PS_MC2') detected by the second pressure sensor (PS_MC2) and transmitted to the electronic controller (ECU) is unrelated to the signal (PS_AC') detected by the first pressure sensor (PS_AC), then the electronic controller (ECU) infers that the loop branches (C1.1; C1.2; C2.1, C2.2) are in reverse contact.

2. The method according to claim 1, Its features are, Step S5: When it is determined that the circuit branches (C1.1, C1.2; C2.1, C2.2) are in reverse contact, the electronic controller (ECU) issues a warning signal.

3. The method according to claim 2, Its features are, The electronic control unit (ECU) provides a warning signal to notify the personnel performing the method, in an optical and / or acoustic manner, that the braking circuit branches (C1.1, C1.2; C2.1, C2.2) have experienced reversed contact.

4. An electronic controller used to increase and regulate the braking pressure in the wheel brakes (WC1-WC4) of an electronically slip-adjustable power-assisted braking system. Its features are, The electronic controller (ECU) is further configured to perform the method according to claim 1.

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