Hydraulic Impact Device Warm-Up Below Accumulator Pre-Charge

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Solution Overview

Problem

Existing hydraulic impact devices in rock drilling machines and hydraulic breakers face challenges in low-temperature operating conditions, leading to increased viscosity of hydraulic fluids, damage to elastomeric materials, and wear of components due to high pressures and movements during warm-up.

Innovation Solution

A pre-heating arrangement that feeds pre-heated hydraulic fluid through a controlled feed channel to the impact device, limiting hydraulic power below the pre-charge pressure of pressure accumulators to prevent movement of separating elements and reduce stress on membranes and sealings, using a control element to manage the flow and pressure during warm-up.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If pre-heated hydraulic fluid is fed to the impact device during warm-up, then the hydraulic system is heated effectively, but high pressure causes movement of separating elements in pressure accumulators leading to membrane damage

Engineering Contradiction:
Improvehydraulic fluid temperatureVSAvoidmembrane integrity
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The invention changes the pressure parameter of the hydraulic fluid during warm-up by using a control element to limit pressure to below the pre-charge pressure of the pressure accumulator. This allows effective heating while preventing membrane movement and damage

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention performs preliminary heating action before normal operation, but controls the pressure during this preliminary phase to be below the accumulator pre-charge pressure, preventing damage to separating elements before they are exposed to full operating pressures

Inventive Principle:
Principle #10Preliminary action

2Productivity

If high hydraulic power is applied during warm-up, then the impact device reaches operating temperature faster, but stress on sealings and membranes increases causing damage

Engineering Contradiction:
Improvewarm-up speedVSAvoidstress on sealings and membranes
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the pressure parameter during the warm-up phase, maintaining it below the pre-charge pressure of the pressure accumulator. This reduces stress on sealings and membranes while still providing effective heating through controlled hydraulic fluid flow

Inventive Principle:
Principle #35Parameter changes

3Power

If pressure is increased above pre-charge pressure during warm-up, then hydraulic power is sufficient for impact device operation, but separating elements move causing compression and volume change in gas space

Engineering Contradiction:
Improvehydraulic powerVSAvoidgas space volume
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The invention changes the pressure parameter to remain below the pre-charge pressure during warm-up, preventing compression of the gas space and movement of separating elements, while still providing sufficient controlled hydraulic power for gentle heating

Inventive Principle:
Principle #35Parameter changes

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

Prevents damage to membranes and sealings, extends their operational life, reduces maintenance, and ensures effective heating without overstressing components, thereby maintaining the integrity and efficiency of the hydraulic system.

Implementation Method 1

transferring heat energy from the hydraulic fluid flow to the percussion device

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

feeding pre-heated hydraulic fluid through at least one feed channel to a hydraulic circuit of the impact device

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP4414530B1Arrangement and method for heating hydraulic impact device
Publication Date: 2025.08.06 SANDVIK MINING & CONSTR OY
  • EP4414530B1 patent drawingFigure 1~2
  • EP4414530B1 patent drawingFigure 3~4
  • EP4414530B1 patent drawingFigure 5~6

AI summary

An arrangement and method for heating an impact device (9) of a rock treating machine (Rtm) in low-temperature operating conditions. The arrangement comprises a warm-up mode (WM) for feeding pre-heated hydraulic fluid through a feed channel (19) to a hydraulic circuit (18) of the impact device. There are one or more hydraulic accumulators (Pa) in the hydraulic circuit. The feed channel is provided with a control element (CE) for limiting the feeding of the pre-heated hydraulic fluid during the warm-up mode. The control element limits the feeding of the pre-heated hydraulic fluid in the feed channel so that separating elements (Se) of the pressure accumulators do not move.