Electrohydraulic Pilot Pressure Control for Flexible Actuator Response

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Solution Overview

Problem

Existing hydraulic systems in working vehicles face challenges in providing flexible control of hydraulic actuators, particularly for slew motors, while maintaining simplicity and cost-effectiveness, as they often require electric position sensors or complex electrohydraulic configurations.

Innovation Solution

An electrohydraulic system combining hydraulic pilot pressure control with electric control, using a controller to receive input signals from pilot pressure sensors and send output signals to actuate the main control valve, allowing a hydraulic joystick to control actuators with flexibility without electric position sensors, and incorporating proportional solenoids for variable actuation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an electric joystick with position sensors is used to control hydraulic actuators, then control flexibility is improved, but device complexity and cost increase

Engineering Contradiction:

Improvecontrol flexibilityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces electric position sensors and electronic control components with a hydraulic sensing mechanism. The pilot pressure sensor detects pilot line pressure generated by joystick movement and converts it to an electrical signal, eliminating the need for complex electric position sensors while maintaining control flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces pilot hydraulic pressure as an intermediary between the mechanical joystick and the electrical control system. The joystick generates pilot pressure, which is sensed and converted to electrical signals, creating a simplified interface that combines mechanical simplicity with electronic control capabilities

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If a hydraulic joystick directly controls the pilot control valve, then system simplicity is improved, but control flexibility deteriorates

Engineering Contradiction:

Improvesystem simplicityVSAvoidcontrol flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent implements feedback by using the pilot pressure sensor to detect the actual pilot line pressure generated by joystick movement and feeding this information back to the controller. This allows the controller to adjust control signals based on actual system state, providing flexibility while maintaining the simple hydraulic joystick interface

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from direct mechanical valve position to pilot pressure level. The joystick controls pilot pressure, which is then sensed and converted to electrical signals that can be flexibly processed by the controller, enabling both simplicity and adaptability

Inventive Principle:

Principle #35Parameter changes

3Speed

If electric control signals are sent directly to solenoids, then response speed is improved, but transient stability deteriorates

Engineering Contradiction:

Improveresponse speedVSAvoidtransient stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent uses the hydraulic pilot circuit and pilot pressure sensor as a cushioning element between the fast electric control signals and the hydraulic actuator. The hydraulic fluid compressibility and the pilot pressure sensing system provide natural damping that reduces transient shocks while maintaining fast response through electronic control

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 configuration enables flexible control of hydraulic actuators, particularly slew motors, by dampening transient changes and restricting rotational orientations, mimicking conventional excavator inertia, while maintaining simplicity and reducing costs.

Implementation Method 1

a first pilot pressure sensor configured to detect pressure in the first pilot line

Methodology Applied

Scientific EffectPressure detection:

Implementation Method 2

a pilot hydraulic circuit comprising a pilot pump, one or more user-operable pilot control valves, and one or more pilot pressure sensors selectively coupled to the pilot pump via the one or more user-operable pilot control valves

Methodology Applied

Scientific EffectHydraulic pressure control: Hydraulic Press

Data Source

PatentEP4726113A1Electrohydraulic system

Publication Date: 2026.04.15 J C BAMFORD EXCAVATORS LTD

Figure 1A~1B
Figure 2
Figure 3

AI summary

Aspects of the present disclosure relate to an electrohydraulic system 10 for a working machine. The system comprises a pilot hydraulic circuit 20 comprising a pilot pump 22 and one or more pilot pressure sensors 28A, 28B selectively coupled to the pilot pump via one or more user-operable pilot control valves 24A, 24B. The system also comprises a main hydraulic circuit 50 comprising a main hydraulic pump 52 and a hydraulic actuator 56 selectively coupled to the main hydraulic pump via a main control valve 54. The system also comprises a controller 80 configured to: receive one or more input signals 82A, 82B from the one or more pilot pressure sensors; and send one or more electric output signals 84A, 84B to actuate the main control valve depending on the one or more input signals received from the one or more pilot pressure sensors.