Electropneumatic Brake Test Mode for Backup Circuit Integrity
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Solution Overview
Problem
The existing electropneumatic brake systems (EBS) fail to regularly check the leak-tightness of the pneumatic backup brake circuit, especially when hillholder or autohold functions are active, leading to delayed activation of these functions and adverse impacts on operability and customer satisfaction.
Innovation Solution
An electropneumatic brake system that includes a service brake actuating element with both electrical and pneumatic channels, a first electronic control system, and a pressure control module with an electromagnetic control valve device and solenoid valve, which activates a test mode by switching to a pneumatic backup brake circuit during partial braking, allowing for the assessment of the pneumatic backup brake circuit's integrity by measuring pressure gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the test mode is carried out only when the driver actuates the brake pedal at standstill, then the pneumatic backup brake circuit can be checked, but the test mode is not executed when hillholder or autohold functions are active, preventing regular checking
Solution Approach 1:
The test mode is executed before the hillholder or autohold function becomes active. The control system detects when the vehicle is at standstill and performs the pneumatic circuit test during this preliminary phase, ensuring the test completes before the holding function prevents brake pedal actuation.
Solution Approach 2:
The system dynamically adjusts the timing of the test mode execution based on vehicle operating conditions. The control system monitors vehicle speed, brake pedal position, and holding function status to determine the optimal moment to perform the test, transitioning from a static test schedule to a dynamic, condition-based execution strategy.
2Reliability
If the test mode is carried out before activation of hillholder or autohold function, then regular checking can be ensured, but the activation of these functions is delayed, adversely impacting operability
Solution Approach 1:
The test mode uses a partial braking action (depressing the brake pedal partially) rather than requiring full braking or extended pedal depression. This partial action is sufficient to activate the pneumatic circuit test while minimizing the time delay before the holding function can activate, balancing thorough testing with operational efficiency.
3Reliability
If the electromagnetic backup solenoid valve is switched to the pass-through position during test mode, then pneumatic pressure can flow to test the circuit, but brake pressure control is interrupted
Solution Approach 1:
The test mode operates as a periodic, temporary interruption of normal brake pressure control. The system switches the solenoid valve to the pass-through position for a brief test duration, then restores normal control. This periodic action allows thorough testing while minimizing the duration of control interruption, maintaining overall system safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures regular checking of the pneumatic brake circuit integrity without delaying the activation of hillholder or autohold functions, providing a seamless transition from electrical to pneumatic brake control and alerting the driver to any leaks or blockages in the pneumatic brake circuit.
Implementation Method 1
at least one pressure sensor, wherein, depending on the electrical brake control signal, the electromagnetic control valve device generates a control pressure for a control input of the relay valve, which, depending on the control pressure, generates an actual brake pressure for the at least one pneumatic brake actuator, which the pressure sensor measures and reports to the second electronic control system
Implementation Method 2
at least one electropneumatic pressure control module, which, depending on the electrical brake control signal, outputs an actual brake pressure, in the course of a brake pressure control adjusts the actual brake pressure to the setpoint brake pressure
Implementation Method 3
the electromagnetic backup solenoid valve is connected by an input to the pneumatic channel and by an output to the control input of the relay valve and can be switched between a pass-through position, in which the input is connected to the output, and a shut-off position, in which the input is shut off with respect to the output
Implementation Method 4
the electromagnetic control valve device generates a control pressure for a control input of the relay valve, which, depending on the control pressure, generates an actual brake pressure for the at least one pneumatic brake actuator
Data Source
AI summary
An electropneumatic brake system (EBS) of a vehicle, which electronically controls a brake-pressure, including: a) a service-brake actuating-element, which is actuatable by a driver, of a service-brake-actuating-device, which has an electrical-channel and at least one pneumatic-channel, wherein, depending on the actuation of the service-brake-actuating-element, an electrical-brake-request-signal, representing a setpoint-brake-pressure, is generated in the electrical-channel and a pneumatic-backup-pressure is generated in the pneumatic-channel; b) a first electronic-control-system, which, depending on a brake-request-signal output by the electrical-channel, outputs an electrical-brake-control-signal; c) at least one electropneumatic-pressure-control-module, which, depending on the electrical-brake-control-signal, outputs an actual-brake-pressure, in the course of a brake-pressure-control adjusts the actual-brake-pressure to the setpoint-brake-pressure and inputs this into at least one pneumatic-brake-actuator; d) wherein the pressure-control-module includes at least one electromagnetic-control-valve-device (EV, AV), at least one relay-valve (RLV), at least one electromagnetic-backup-solenoid-valve (BV), a second electronic-control-system and at least one pressure-sensor (DS), wherein, depending on the electrical-brake-control-signal, the electromagnetic-control-valve-device (EV, AV) generates a control-pressure for a control-input of the relay-valve (RLV), which, depending on the control-pressure, generates an actual-brake-pressure for the at least one pneumatic-brake-actuator, which the pressure-sensor (DS) measures/reports to the second electronic-control-system of the pressure-control-module, e) wherein the electromagnetic-control-valve-device (EV, AV) and the at least one electromagnetic-backup-solenoid-valve (BV) are electrically-controlled by the second electronic-control system, f) wherein the electromagnetic-backup-solenoid-valve (BV) is connected by an input to the pneumatic-channel and by an output to the control-input of the relay-valve (RLV) and can be switched between a pass-through-position, in which the input is connected to the output, and a shut-off position, in which the input is shut-off with respect to the output, g) wherein the electromagnetic-control-valve-device (EV, AV) connects the control-input of the relay-valve (RLV) to a pressure-sink or to a compressed-air-supply or shuts it off from the pressure-sink and from the compressed-air-supply, h) wherein a pneumatic-backup-brake-circuit of the electropneumatic-brake-system includes at least the pneumatic-channel of the service-brake-actuating-device, the relay-valve (RLV), the at least one electromagnetic-backup-solenoid-valve (BV) and at least one pneumatic-line connecting the at least one pneumatic-channel to the input of the at least one electromagnetic-backup-solenoid-valve (BV), and i) wherein an electrical-brake-circuit of the electropneumatic-brake-system includes at least the electrical-channel of the service-brake-actuating-device, the first electronic-control-system, the second electronic-control-system, the electromagnetic-control-valve-device (EV, AV), the at least one electromagnetic-backup-solenoid-valve (BV), the relay-valve (RLV) and the pressure-sensor (DS), j) wherein test routines of a test-mode that are configured so that the following test-mode-conditions are cumulatively satisfied when the electrical-brake-circuit is intact and the test-mode is activated are implemented in the first electronic-control-system and/or in the second electronic-control-system: j1) when a vehicle is being driven, the service-brake-actuating-device is actuated by the driver so that a partial-braking, deviating from emergency-braking or full-braking, is performed, and j2) a difference between the backup-pressure generated in the pneumatic-channel and a first pressure-value is greater than the actual-brake-pressure measured by the at least one pressure-sensor (DS), k) wherein the brake-pressure-control ends and the electromagnetic-control-valve-device (EV, AV) and the electromagnetic-backup-solenoid-valve (BV) are switched into a test-switching-state, in which the control-input of the relay-valve (RLV) is shut-off by the electromagnetic-control-valve-device (EV, AV) from the compressed-air-supply and from the pressure-sink and the electromagnetic-backup-solenoid-valve (BV) is switched from the shut-off-position into the pass-through-position, and l) if the pressure-gradient of the brake-pressure measured by the at least one pressure-sensor (DS), l1) is greater than zero, a first signal, representing an intact-backup-brake-circuit, is generated, or l2) is equal to zero or less than zero, a second signal, representing a defective backup-brake-circuit, is generated, or m) then a difference between the backup-pressure generated in the pneumatic-channel and a second pressure-value is greater than the actual-brake-pressure measured by the pressure-sensor (DS), the second-signal, representing a defective backup-brake-circuit, is generated.