Braking Compressor Torque Control for EV Energy Dissipation

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Solution Overview

Problem

Existing solutions for dissipating braking energy in electric vehicles are limited by battery storage capacity, often require cooling systems for energy dissipation, and may not allow for pre-engagement of the braking system before a braking situation occurs.

Innovation Solution

A vehicle arrangement that includes a first electric motor with a gearbox connection to the drive shaft and a braking compressor, where the compressor is connected to the motor shaft via a compressor clutch, allowing for controlled energy dissipation through air compression, and includes mass flow rate controlling means to manage compressor torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If battery is used for storing braking energy, then energy storage capacity is improved, but the braking capacity is limited when battery storage limits are reached

Engineering Contradiction:

Improveenergy storage capacityVSAvoidbraking capacity

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent combines the battery energy storage system with a compressor-based energy dissipation system. The compressor is mechanically coupled to the drive shaft and can dissipate braking energy by compressing air into storage tanks, providing an additional energy management pathway that complements the battery system and prevents braking capacity limitations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The compressor system serves multiple functions: it acts as a braking energy dissipation device, a power take-off (PTO) system for auxiliary power, and an energy management component. This multi-functionality allows the same mechanical component to address both braking capacity needs and auxiliary power requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of energy

If retarders and resistors are used for dissipating braking energy, then braking energy dissipation is improved, but the cooling system requirements increase resulting in larger radiator area and fan performance

Engineering Contradiction:

Improvebraking energy dissipationVSAvoidcooling system requirements

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent replaces the thermal dissipation approach (which requires large cooling systems) with a mechanical energy conversion approach. The compressor converts braking energy directly into potential energy by compressing air, eliminating the need for extensive cooling infrastructure while achieving the same energy dissipation goal.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Force

If braking system is engaged before braking situation, then pre-engagement capability is improved, but compressor torque may exceed maximum torque limit causing mechanical wear or breakage

Engineering Contradiction:

Improvebraking forceVSAvoidcompressor mechanical integrity

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The patent employs dynamic control of the compressor engagement through a control unit that monitors drive shaft speed and adjusts compressor clutch engagement accordingly. The system uses speed thresholds to control clutch engagement and disengagement, and dynamically adjusts mass flow rate through the compressor to prevent torque exceeding while maintaining pre-engagement capability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control unit continuously monitors drive shaft speed and uses this feedback to control the compressor clutch engagement and mass flow rate. This closed-loop control ensures that the compressor torque remains within safe limits while enabling pre-engagement of the braking system.

Inventive Principle:

Principle #23Feedback

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 enables efficient energy dissipation during braking, reduces the load on the cooling system, allows for pre-engagement of the braking system, and helps in maintaining compressor torque within safe limits to prevent mechanical wear or breakage.

Implementation Method 1

a braking compressor (30) comprising a compressor shaft (32) being arranged to be mechanically connected to the first shaft (12)

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

mass flow rate controlling means (60) arranged for controlling the air mass flow rate through the braking compressor (30)

Methodology Applied

Scientific EffectFluid flow control:

Data Source

PatentEP4194286B1A vehicle arrangement and method for braking

Publication Date: 2025.04.02 VOLVO TRUCK CORP

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AI summary

The invention relates to a vehicle arrangement for braking comprising at least a first electric motor (10) comprising a first shaft (12) being arranged to be mechanically connected to a drive shaft (55) of said vehicle (1) via a gear box (50), and a braking compressor (30) comprising a compressor shaft (32) being arranged to be mechanically connected to said first shaft (12) of said first electric motor (10) via a compressor clutch (35), such that said first shaft (12) drives said compressor shaft (32), wherein said first shaft (12) is connected to said gearbox (50) via a first motor clutch (14) and a first gearbox shaft (13), said arrangement further comprising a mass flow rate controlling means (60) arranged for controlling the air mass flow rate through said compressor (30). The invention also relates to a method for controlling a vehicle arrangement, a method for braking a shaft of an electric motor, a control unit (100), a vehicle (1000), a computer program and to a computer readable medium.