Hydraulic Excavator Pilot Conduit Volume Segmentation
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Solution Overview
Problem
Hydraulic excavators experience minute vibrations in the control lever during boom-lowering operations due to abrupt fluctuations in pilot pressure outputted by the pilot pressure control valve, causing discomfort to the operator.
Innovation Solution
The design includes a hydraulic excavator configuration with a larger upstream pilot conduit volume compared to the downstream conduit, featuring a proportional solenoid valve and a pilot switching valve, which reduces the rate of hydraulic oil decrease and pressure fluctuations, thereby minimizing vibrations. Additionally, an oil supply conduit with an inner diameter equal to or larger than the upstream conduit promotes supplementary oil supply and reduces pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pilot pressure control valve responds quickly to control lever operation, then the boom-lowering operation becomes more responsive, but abrupt pressure fluctuations occur causing minute vibrations in the control lever
Solution Approach 1:
The patent introduces a cushioning chamber (53a) upstream of the proportional solenoid valve that accumulates pilot pressure in advance. When the solenoid valve opens, this pre-stored pressure cushions against abrupt pressure drops, preventing the spool-retainer collisions that cause vibrations while maintaining rapid response capability
Solution Approach 2:
The cushioning chamber acts as an intermediary element between the pilot pressure control valve and the proportional solenoid valve. It mediates the pressure transmission by storing and releasing pilot pressure as needed, smoothing out fluctuations before they reach the control lever
2Object-affected harmful factors
If the upstream pilot conduit has large volume to suppress pressure fluctuations, then vibrations are reduced, but the system response time increases
Solution Approach 1:
The pilot conduit is segmented into an upstream portion (53a) with larger volume for cushioning and a downstream portion with smaller volume for rapid response. This segmentation allows each section to optimize for its specific function while working together as a complete system
Solution Approach 2:
The upstream pilot conduit is designed with locally different properties (larger volume) compared to the downstream conduit. This local quality change creates a pressure reservoir exactly where needed to cushion fluctuations, while maintaining overall system responsiveness
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 effectively suppresses the occurrence of minute vibrations in the control lever, enhancing operator comfort and maintaining precise control during land leveling operations.
Implementation Method 1
a proportional solenoid valve (73) is provided in a first pilot conduit (53) connecting the first pilot pressure control valve (41A) and the pilot switching valve (37)
Implementation Method 2
A volume of the upstream pilot conduit is larger than a volume of the downstream pilot conduit. In the hydraulic excavator, a rate of decrease in hydraulic oil in the upstream pilot conduit when the hydraulic oil flows from the upstream pilot conduit to the downstream pilot conduit via the proportional solenoid valve can be reduced
Data Source
AI summary
There is provided a hydraulic excavator in which occurrence of minute vibrations in a control lever can be suppressed. The hydraulic excavator includes: a first pilot pressure control valve outputting a pilot pressure in accordance with operation of the control lever; an upstream pilot conduit having one end connected to the first pilot pressure control valve; a proportional solenoid valve connected to the other end of the upstream pilot conduit; a downstream pilot conduit having one end connected to the proportional solenoid valve; and a pilot switching valve for a boom having a second pilot port connected to the other end of the downstream pilot conduit, and controlling operation of the boom. A volume of the upstream pilot conduit is larger than a volume of the downstream pilot conduit.