Clutch Actuator Warm-Up by Cyclic Pressurization in Cold Starts

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Solution Overview

Problem

Clutch actuators in vehicle transmissions face difficulties in cold conditions, particularly with air leakage issues, making it challenging to disengage the clutch and control it properly, and existing methods to warm up the clutch are not sufficiently effective.

Innovation Solution

A method involving repeatedly pressurizing the clutch actuator using pressurized fluid to efficiently warm up the seals, with adjustments in pressure magnitude, duration, and frequency based on temperature, to ensure the clutch actuator functions correctly and quickly, preventing faulty operations and ensuring the vehicle can start promptly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vehicle is started in cold conditions, then the clutch actuator experiences air leakage and cannot disengage properly, but increasing the rotational speed of the drive aggregate to warm up the clutch takes excessive time and delays vehicle operation

Engineering Contradiction:
Improveclutch actuator functionalityVSAvoidvehicle start time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies periodic action by repeatedly pressurizing the clutch actuator in cycles rather than continuously. The control unit performs multiple pressurization cycles with each cycle consisting of pressurizing the actuator and then releasing pressure, allowing heat to build up in the seals through repeated compression and expansion of the pressurized air. This periodic approach warms up the seals efficiently without requiring prolonged engine idle operation.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent utilizes pneumatics by using pressurized air from the vehicle's air supply system to warm up the clutch actuator seals. The control unit opens a supply valve to introduce pressurized air into the actuator chamber, and the compression and expansion of this gas directly heats the seals through adiabatic heating and mechanical work, providing rapid warming without mechanical friction or prolonged operation.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Productivity

If the clutch actuator is repeatedly pressurized to warm up seals rapidly, then the warming up procedure is shortened, but excessive pressure or prolonged pressurization may cause damage to the actuator components

Engineering Contradiction:
Improvewarming up speedVSAvoidactuator component durability
Core Design Contradiction:
ProductivityVSStrength

Solution Approach 1:

The periodic pressurization cycles allow the system to build heat gradually through repeated compression and expansion. Each cycle compresses the air to heat the seals, then releases pressure to allow cooling and prevent overheating. This cyclic approach achieves rapid warming while naturally limiting maximum temperature and pressure exposure, protecting components from damage.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The control unit monitors the clutch actuator's response to pressurization and uses this feedback to determine when the warming procedure should stop. The system detects whether the actuator responds properly to pressurization signals, and when the seals are sufficiently warm and functional, the control unit terminates the repeated pressurization cycles, preventing over-pressurization and component damage.

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 method effectively warms up the clutch actuator seals in cold conditions, reducing the time required for the vehicle to start and extending the service life by ensuring the clutch actuator is functional before the vehicle takes off, thereby preventing unnecessary fault codes and ensuring reliable transmission operation.

Implementation Method 1

repeatedly pressurizing the clutch actuator by use of the pressurized fluid until a state is reached indicative of the clutch actuator being functional

Methodology Applied
Scientific EffectCompression heating: Adiabatic Heating

Implementation Method 2

the energy in the fluid can efficiently warm up seals of the clutch actuator which are too cold to function properly

Methodology Applied
Scientific EffectThermal energy transfer: Conduction (thermal)

Data Source

PatentEP4015862B1A method for automatically warming up a clutch actuator
Publication Date: 2023.11.08 VOLVO TRUCK CORP
  • EP4015862B1 patent drawingFigure 1
  • EP4015862B1 patent drawingFigure 2~3
  • EP4015862B1 patent drawingFigure 4

AI summary

The invention relates to a method for automatically warming up a clutch actuator (1) for a clutch (2) of a transmission (10) in a vehicle (100), wherein the clutch actuator (1) is operable by use of pressurized fluid and configured to actuate the clutch (2) from an engaged to a disengaged state, and/or vice versa, the method comprising: - identifying (S1) if a temperature is below a predetermined temperature value and if the clutch actuator is leaking, and if it is identified that the temperature is below the predetermined temperature value and that the clutch actuator is leaking; then - repeatedly (S2) pressurizing the clutch actuator by use of the pressurized fluid until a state is reached indicative of the clutch actuator (1) being functional, or until a maximum run out state is reached indicative of a faulty clutch actuator.