HVAC Blower Motor Control Using Waste Heat for Cabin Heating

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Solution Overview

Problem

Existing HVAC blower devices in vehicles require additional components like heat exchangers or auxiliary heaters to heat the interior, which incur costs and complexity, and existing control methods aim to minimize waste heat generation.

Innovation Solution

A control method for an HVAC blower device that generates increased waste heat by altering the electric motor's control, specifically changing the pre-commutation angle and increasing current to convert more energy into heat while maintaining air flow volume, without increasing torque or speed, using the blower device itself as a heat source.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If additional components like heat exchangers or auxiliary heaters are added to heat the vehicle interior, then the heating capability is improved, but the device complexity and cost increase

Engineering Contradiction:
Improvevehicle interior temperatureVSAvoidHVAC system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The electric motor of the blower device heats the air flow using its own waste heat, without requiring external heating components. The motor acts as both the driver of the system and the heat source, eliminating the need for separate heating systems

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The waste heat generated by the electric motor, which was previously considered a harmful byproduct to be minimized, is converted into a useful heating source for the vehicle interior. The control method deliberately increases waste heat generation to achieve heating functionality

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Temperature

If the electric motor is controlled to generate increased waste heat, then the heating capability is improved, but the energy efficiency for generating rotary motion decreases

Engineering Contradiction:
Improveair flow temperatureVSAvoidmotor energy efficiency
Core Design Contradiction:
TemperatureVSUse of energy by moving object

Solution Approach 1:

The control method changes the operating parameters of the electric motor, specifically adjusting the pre-commutation angle and increasing current, to shift the energy conversion ratio from mechanical output to thermal output. This allows the motor to operate in a mode that prioritizes heat generation over rotational efficiency

Inventive Principle:
Principle #35Parameter changes

3Temperature

If the air flow volume is increased to improve heating, then the heating capability is improved, but the motor power consumption increases

Engineering Contradiction:
Improvevehicle interior temperatureVSAvoidmotor power consumption
Core Design Contradiction:
TemperatureVSPower

Solution Approach 1:

Instead of increasing power consumption to generate more heat through increased air flow, the method converts the motor's inherent waste heat into a useful heating source. The air flow remains essentially constant, but the temperature of the air is increased due to heat transfer from the motor components

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The motor's waste heat, which would otherwise be lost to the environment, is utilized to heat the air flow. This self-service approach allows the system to provide heating functionality without additional power consumption or increased air flow volume

Inventive Principle:
Principle #25Self-service

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

Simplifies the HVAC system by eliminating the need for additional heating components and efficiently heats the vehicle interior using the blower device as a heat source, reducing complexity and cost.

Implementation Method 1

the electric motor generates increased waste heat, which heats the generated air flow

Methodology Applied
Scientific EffectWaste heat generation: Joule Heating

Implementation Method 2

the windings of the electric motor are energized using an electric commutator in such a way that a rotating magnetic field is created, which drives the motor rotor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4348060B1Control method for a heated fan
Publication Date: 2025.07.09 ROBERT BOSCH GMBH
  • EP4348060B1 patent drawingFigure 1
  • EP4348060B1 patent drawingFigure 2

AI summary

The invention relates to a control method (100) for a blower device (1), more particularly an HVAC blower for a motor vehicle, the blower device (1) comprising at least one electric motor (20), which drives a ventilator device (10) that produces an air flow, and the produced air flow at least partly flowing around and/or through the electric motor (20). The control method comprises the steps of: - controlling (110) the electric motor (20) such that an air flow is produced by means of the ventilator device (10); - measuring (120) the temperature of the air; - changing (130) the control of the electric motor (20) in accordance with the measured temperature of the air such that the electric motor (20) produces increased heat output, which heats the air of the produced air flow.