Hydraulic Control Apparatus for Work Machine Idling
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Solution Overview
Problem
Conventional hydraulic control systems for work machines fail to maintain the minimum discharge flow rate from a hydraulic pump when engine speed drops below the rated speed, leading to inefficient fuel consumption and pressure loss due to excessive hydraulic fluid discharge.
Innovation Solution
A hydraulic control apparatus that includes an idling detection device and a negative control pressure control device to maintain a higher negative control pressure when the hydraulic actuator is not operating, ensuring the minimum discharge flow rate is maintained irrespective of engine speed, using a solenoid proportional pressure reduction valve to set the negative control pressure to a predetermined value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pump characteristic is set based on rated engine speed, then the discharge flow rate can be minimized at rated speed, but the discharge flow rate cannot be maintained at minimum when engine speed decreases
Solution Approach 1:
The patent applies dynamics by making the negative control pressure adjustable based on engine speed conditions. The control system dynamically changes the negative control pressure from a fixed value to a variable value that adapts to different engine speeds, ensuring optimal discharge flow rate control whether the engine is running at rated speed or lower speeds.
Solution Approach 2:
The patent changes the parameter of negative control pressure from a fixed predetermined value to a variable value that depends on engine speed. When engine speed is lower than rated speed, the system increases the negative control pressure above the predetermined value to maintain minimum discharge flow rate, thereby reducing hydraulic energy loss and improving fuel efficiency.
2Use of energy by moving object
If the negative control pressure is increased to minimize discharge flow rate, then fuel efficiency improves, but the system cannot adapt when engine speed varies
Solution Approach 1:
The system transitions from a static negative control pressure setting to a dynamic control mechanism that automatically adjusts the negative control pressure based on detected engine speed. This enables the system to maintain optimal energy efficiency across varying operating conditions rather than being fixed for rated speed only.
Solution Approach 2:
The patent implements feedback control by detecting the actual engine speed and using this information to adjust the negative control pressure accordingly. The control system receives feedback about engine speed deviations from rated speed and responds by modifying the negative control pressure to maintain minimum discharge flow rate and optimize fuel efficiency.
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 approach maintains the minimum discharge flow rate from the hydraulic pump, improving fuel efficiency by reducing hydraulic energy loss during idle operations and ensuring consistent performance across varying engine speeds.
Implementation Method 1
a solenoid proportional pressure reduction valve to set the negative control pressure to a predetermined value
Implementation Method 2
the discharge flow rate from a hydraulic pump is controlled by means of a negative control pressure in a center bypass... the choking characteristic of an orifice used for negative controls
Data Source
AI summary
A hydraulic pump driven by an engine, a hydraulic actuator, and a negative control circuit are provided on an open center hydraulic circuit, for guiding the hydraulic pressure in the center bypass to the hydraulic pump, as a negative control pressure. A negative control pressure control device controls the negative control pressure to an arbitrary value is also provided. The pump characteristic of the hydraulic pump is set such that the discharge flow rate is minimized when the negative control pressure in the negative control circuit is equal to or greater than a first predetermined pressure. Furthermore, an idling detection device that detects whether the hydraulic actuator is in a non-operated state or not is provided. The negative control pressure is forcefully controlled to the first predetermined pressure or higher when the non-operating state is detected.