Hydraulic Motor Casing Cooling via Flushing Passage

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Solution Overview

Problem

Existing hydraulic motors, particularly those with reduction gears, face insufficient cooling due to low flow rates of leak oil or reduced hydraulic oil pressure, leading to overheating issues regardless of operating conditions.

Innovation Solution

A hydraulic motor design that incorporates a flushing passage connected to the casing chamber, allowing hydraulic oil from the low pressure side of the motor passages to flow into the casing chamber, where it absorbs heat, ensuring sufficient cooling regardless of operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If leak oil is used to cool the casing, then cooling function is provided, but the flow amount is insufficient leading to inadequate cooling

Engineering Contradiction:
Improvecasing temperatureVSAvoidflow amount of leak oil
Core Design Contradiction:
TemperatureVSQuantity of substance

Solution Approach 1:

The patent introduces a flushing passage as an intermediary channel that directs hydraulic oil from the low-pressure side to the casing chamber. This mediator passage ensures sufficient cooling fluid flow independent of leak oil quantity, resolving the contradiction between providing cooling function and maintaining adequate flow amount.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Speed

If hydraulic oil pressure is reduced for low speed operation, then speed control is achieved, but cooling performance deteriorates

Engineering Contradiction:
Improvemotor rotation speedVSAvoidcasing temperature
Core Design Contradiction:
SpeedVSTemperature

Solution Approach 1:

The patent implements a dynamic cooling system where the flushing passage is selectively activated based on operating conditions. The switching valve dynamically directs hydraulic oil to the flushing passage when cooling is needed, ensuring adequate cooling flow regardless of motor speed or hydraulic pressure level.

Inventive Principle:
Principle #15Dynamics

3Reliability

If a flushing passage is added to improve cooling, then cooling reliability is improved, but device complexity increases

Engineering Contradiction:
Improvecooling reliabilityVSAvoidpassage structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The flushing passage is merged with the existing hydraulic oil passages and casing structure. The passage utilizes available spaces within the motor housing and integrates with the pressure and return oil passages, thereby improving cooling reliability while minimizing additional structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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

The design effectively maintains the casing and adjacent reduction gear at a lower temperature, preventing overheating and ensuring reliable operation across various operating conditions.

Implementation Method 1

a flushing passage (47) that is in communication with the casing chamber (58) and extracts a portion of hydraulic liquid from a low pressure side among the first motor passage (41) and the second motor passage (42) and leads it to the casing chamber (58)

Methodology Applied
Scientific EffectThermal convection: Convection

Data Source

PatentEP2806154B1Hydraulic motor
Publication Date: 2019.12.04 KYB CORP
  • EP2806154B1 patent drawingFigure 1
  • EP2806154B1 patent drawingFigure 2
  • EP2806154B1 patent drawingFigure 3

AI summary

A hydraulic motor includes a motor mechanism that rotates by hydraulic liquid that is supplied/discharged from a hydraulic liquid pressure source through one of a first motor passage and a second motor passage. The hydraulic motor comprises a casing that defines a casing chamber which accommodates the motor mechanism, and a flushing passage that is in communication with the casing chamber and extracts a portion of the hydraulic liquid from a low pressure side among the first motor passage and the second motor passage and leads it to the casing chamber.