Transmission Hydraulic Assembly With Threshold Accumulator Charging

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Solution Overview

Problem

Existing hydraulic arrangements for vehicle transmissions face instability in system pressure, particularly during clutch actuation and when the engine is not running, leading to undesirably low pressures and inefficient clutch control.

Innovation Solution

A hydraulic arrangement that includes a pressure accumulator and a valve assembly to charge the accumulator only when system pressure reaches a predetermined threshold, ensuring stable pressure supply and rapid charging, thereby enhancing hydraulic stability and clutch control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the pressure accumulator is continuously connected to the hydraulic circuit, then pressure support is available, but the system pressure cannot be stabilized before charging and pressure drops occur during charging

Engineering Contradiction:
Improvehydraulic stabilityVSAvoidsystem pressure stability
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

A valve assembly is introduced as an intermediary component between the pressure accumulator and the hydraulic circuit. This valve assembly controls the charging process by opening only when system pressure exceeds a threshold value, thereby mediating the interaction between the accumulator and the hydraulic circuit to prevent pressure instability and drops during charging.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If the pressure accumulator is charged rapidly to provide pressure support, then pressure availability improves, but pressure drops in the hydraulic circuit occur during charging

Engineering Contradiction:
Improvepressure charging speedVSAvoidpressure drop during charging
Core Design Contradiction:
ProductivityVSStress or pressure

Solution Approach 1:

The valve assembly incorporates a pressure threshold mechanism that provides feedback control for the charging process. The valve monitors system pressure and opens for rapid charging only when pressure exceeds the threshold value, creating a feedback-based control system that enables rapid charging while preventing pressure drops by charging only when pressure conditions are appropriate.

Inventive Principle:
Principle #23Feedback

3Reliability

If the valve assembly controls charging based on pressure threshold, then pressure stability is improved, but device complexity increases

Engineering Contradiction:
Improvepressure stabilityVSAvoidvalve assembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The valve assembly is designed to automatically control the charging process based on system pressure conditions without requiring external control systems. The pressure threshold mechanism enables the valve to self-regulate opening and closing based on pressure feedback, providing intelligent pressure stability control while minimizing complexity by eliminating the need for additional sensors, controllers, or complex control logic.

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

This solution stabilizes system pressure, reduces periods of low pressure, and optimizes clutch actuation by allowing targeted charging and discharging of the pressure accumulator, resulting in improved hydraulic stability and clutch control across various operating states.

Implementation Method 1

a pressure accumulator (30) for intermittent or temporary support of the hydraulic circuit (24) in the event of specific pressure requirements

Methodology Applied
Scientific EffectHydraulic pressure accumulation: Hydraulic Accumulator

Implementation Method 2

it has a charging valve unit (40), which acts as a lockable hydraulic connection between the pump (22) and the pressure accumulator (30). The hydraulic connection is locked at a system pressure below the predetermined pressure threshold value p_sch

Methodology Applied
Scientific EffectPressure-controlled valve operation: Valve

Data Source

PatentEP4095392A1Hydraulic assembly for a vehicle transmission
Publication Date: 2022.11.30 DEERE & CO
  • EP4095392A1 patent drawingFigure 1
  • EP4095392A1 patent drawingFigure 2~5
  • EP4095392A1 patent drawing

AI summary

The invention relates to a hydraulic arrangement (12) for a vehicle transmission (14). This hydraulic arrangement (12) includes a hydraulic pump (22) for providing a system pressure (p_sys) within a hydraulic circuit (24) and a pressure accumulator (30) for temporarily supplying pressure to the hydraulic circuit (24). A valve arrangement (34) for charging the pressure accumulator (30) after reaching or exceeding a predetermined pressure threshold (p_sch) of the system pressure (p_sys) starting from an increasing system pressure (p_sys) is hydraulically connected between the pump (22) and the pressure accumulator (30).