Compressor Clutch Control for High-Speed Stress Reduction

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Solution Overview

Problem

Compressor systems in commercial vehicles face extreme mechanical and thermal stress due to high engine speeds, particularly during engine braking, as the transmission ratio designed for low speeds results in excessive air production, leading to potential damage.

Innovation Solution

A control unit that dynamically manages the clutch to open and close based on maximum permissible compressor or engine speed, reducing mechanical and thermal loads by limiting compressor operation when speeds exceed set limits, and utilizing a transmission ratio of less than one to maintain air supply while minimizing stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the transmission ratio is reduced to meet low-speed air requirements, then the air supply at low engine speeds is improved, but the compressor experiences extreme mechanical and thermal stress at high engine speeds

Engineering Contradiction:
Improveair supply capabilityVSAvoidcompressor durability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The clutch connection between the compressor and drive motor is made dynamically controllable through a control unit that monitors engine speed and adjusts clutch engagement accordingly. This allows the system to adapt the mechanical connection state based on operating conditions, resolving the contradiction by disengaging the clutch when engine speed exceeds a threshold to protect the compressor while maintaining engagement when air supply is needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of the clutch (engaged/disengaged states) based on engine speed parameters. By monitoring engine speed and adjusting the clutch state, the system optimizes the balance between air supply requirements and compressor protection, allowing the same transmission ratio to serve both low-speed air demand and high-speed compressor protection needs.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the clutch remains engaged during engine braking to protect material, then the compressor is protected from extreme stress, but compressed air generation is lost when air may be required for service brake

Engineering Contradiction:
Improvecompressor protectionVSAvoidcompressed air generation
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The control unit continuously monitors engine speed and uses this feedback to make real-time decisions about clutch engagement. During engine braking, when engine speed exceeds a predetermined threshold, the control unit disengages the clutch to protect the compressor. The system maintains this disengaged state only as long as necessary, allowing compressed air generation to resume when engine speed returns to normal operating ranges, thus balancing protection needs with air supply requirements.

Inventive Principle:
Principle #23Feedback

3Reliability

If the clutch is opened to reduce load on the compressor, then mechanical and thermal stress is reduced, but compressed air supply is interrupted

Engineering Contradiction:
Improvecompressor load reductionVSAvoidcompressed air supply
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The clutch engagement is controlled periodically based on engine speed cycles rather than being continuously engaged or disengaged. During normal operation, the clutch remains engaged to maintain air supply. When engine braking occurs and engine speed exceeds the threshold, the clutch is temporarily disengaged to reduce load. This periodic engagement/disengagement pattern based on operational cycles allows the system to alternate between air supply mode and compressor protection mode, resolving the contradiction between continuous air supply and periodic load reduction.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2234855B1Compressor and method for controlling a compressor for the compressed air supply of a utility vehicle
Publication Date: 2017.08.09 KNORR BREMSE SYSTEME FUER NUTZFAHIZEUGE GMBH
  • EP2234855B1 patent drawingFigure 1
  • EP2234855B1 patent drawingFigure 2
  • EP2234855B1 patent drawingFigure 3

AI summary

The invention relates to a compressor system (16) for the compressed air supply of a utility vehicle (14), wherein said compressor system (16) comprises a compressor (18) for compressed air generation, a transmission (20) for transmitting torque from a drive motor (12) to said compressor (18), a clutch (22) for disconnecting the connection between compressor (18) and drive motor (12), and a control unit (10) for opening and closing said clutch (22). According to the invention, it is provided that the control unit (10) is capable of opening the clutch (22) in the event a settable maximum allowed compressor speed or motor speed of the drive motor (12) is exceeded and to close the open clutch (22) temporarily when the motor speed is greater than the maximum allowed motor speed. Furthermore, the invention relates to a method for controlling a compressor system.