Redundant Pneumatic Compressor Control for Vehicle Air Systems
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Solution Overview
Problem
Conventional electronic air treatment devices for commercial vehicles may fail to maintain an auxiliary braking effect due to sensor malfunctions, where incorrect pressure readings prevent the compressor from activating, leading to insufficient system pressure and a lack of warning to the driver.
Innovation Solution
The implementation of a redundant pneumatic compressor control system, featuring a pneumatically pilot-controlled compressor control valve that switches on the compressor when system pressure drops below a defined lower limit, ensuring pressure replenishment and maintaining the auxiliary braking effect, even if the electronic control unit fails to recognize a subcritical pressure state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If an electronic control unit with pressure sensors is used to control the compressor, then the system can automatically manage compression and regeneration phases, but sensor malfunctions may cause incorrect pressure readings that prevent the compressor from activating when needed
Solution Approach 1:
The patent implements a redundant pneumatic control mechanism that acts as a backup before the electronic control fails completely. When system pressure drops below a threshold, the pneumatic control automatically activates the compressor without relying on electronic sensors or control units, ensuring continuous operation and preventing brake system failure.
Solution Approach 2:
The patent introduces a pneumatic control mechanism as an intermediary between the system pressure and the compressor activation. This pneumatic intermediary uses direct pressure differential action on a control valve to trigger compressor startup, bypassing the faulty electronic sensing path and providing a reliable backup control route.
2Device complexity
If a single electronic control path is used, then the device complexity is reduced, but the system becomes vulnerable to sensor failures that go undetected
Solution Approach 1:
The patent segments the compressor control function into two independent pathways: an electronic control path using sensors and control units, and a pneumatic control path using pressure-differential actuation. This segmentation allows the system to maintain functionality even if one path fails, as each pathway can operate independently to activate the compressor when needed.
Solution Approach 2:
The pneumatic control mechanism serves as a pre-established backup that activates automatically when electronic control fails. By having this redundant pathway in place beforehand, the system cushions against the effects of sensor malfunctions without requiring complex diagnostic or warning systems.
3Measurement precision
If the compressor control relies solely on electronic sensors, then measurement precision can be high, but false readings may trigger incorrect compressor operation
Solution Approach 1:
The pneumatic control mechanism acts as an intermediary verification layer that does not rely on electronic sensor readings. Instead, it directly responds to actual system pressure through pneumatic differential action on the control valve, providing a fail-safe activation mechanism that bypasses potentially faulty electronic measurement paths.
Solution Approach 2:
The pneumatic control system is self-actuating based on actual system pressure conditions. When pressure drops below the threshold, the pneumatic differential automatically opens the control valve to activate the compressor, without requiring electronic sensing, signal processing, or control decisions. This self-service mechanism ensures reliable activation based on physical reality rather than electronic interpretation.
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
This solution guarantees the replenishment of system pressure and maintains the auxiliary braking effect in error scenarios, ensuring the vehicle's safety by automatically switching on the compressor and providing a warning to the driver, even with faulty sensor readings.
Implementation Method 1
an air dryer unit (1) for drying compressed air generated by a compressor (2)
Implementation Method 2
an electromagnetic compressor control valve (16) connected to the control unit for switching the pneumatically switchable compressor (2) on and off
Implementation Method 3
based on a determined by at least one pressure sensor (22a, 22b, 22c) and as an input signal of the electronic control unit (17) system pressure measured value supplied to the unit (17)
Data Source
Figure 1~2
AI summary
The invention relates to an air preparation device having an electronic control unit (17) for supplying at least one load circuit (6 - 12) of a vehicle with dried system air, comprising an air dryer unit (1) for drying compressed air produced produced by an pneumatically switchable compressor (2), which air dryer unit supplies the at least one load circuit (6 - 12) with dried compressed air via at least one overflow valve (13a - 13f), wherein an electromagnetic regeneration valve (18) is provided which is connected to the control unit (17) and returns dried compressed air along a regeneration path through the air dryer unit (1) in order to regenerate the air dryer unit (1), and an electromagnetic compressor control valve (16) is provided which is likewise connected to the control unit (17), for switching the pneumatically switchable compressor (2) on and off via a pneumatic switching port (14), on the basis of a system pressure measurement value determined by at least one pressure sensor (22a - 22c) and supplied to the electronic control unit (17) as an input signal. For redundant pneumatic compressor activation, a pneumatically pilot-controlled further compressor control valve (23) is provided, to which the system pressure or a pressure proportional thereto is applied at a control inlet (24) in order to switch on the compressor (2) by activation of the pneumatic switching port (14) after the system pressure has dropped below a lower limit value.