Pilot Hydraulic Bypass Circuit for Gate Lock Lever Safety
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Solution Overview
Problem
Conventional construction machines face issues with unintentional operation of working and traveling system actuators due to the design of gate lock levers and unlock switches, leading to safety concerns and increased costs associated with complex electric components and reliability processes.
Innovation Solution
A hydraulic system configuration that includes a pilot pump, pressure reducing valve type pilot valve, gate lock valve, throttle, check valve, bypass line, and lock switching valve to manage pilot pressure oil flow, ensuring the actuators are not unintentionally operated by switching between high and low pressure states based on the gate lock lever position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate lock lever is provided to control operation and stop of the hydraulic circuit, then safety is improved, but unintentional operation of actuators occurs when the control lever device is at an operation position
Solution Approach 1:
The patent introduces a gate lock valve as an intermediary component between the control lever device and the hydraulic circuit. This valve mediates the connection by requiring a specific operation sequence: the gate lock lever must be operated first to open the gate lock valve, establishing hydraulic communication between the pilot pump and pilot delivery line, before the control lever device can activate actuators. This intermediary mechanism prevents unintentional operation while maintaining safety.
2Reliability
If another unlock switch is provided in addition to the gate lock lever, then safety is further improved, but a huge number of processes are required for ensuring reliability or expensive components are needed
Solution Approach 1:
The patent extracts the unlocking function from a separate electric switch component and integrates it directly into the mechanical gate lock lever itself. The gate lock lever now performs dual functions: it mechanically locks the system and simultaneously operates the gate lock valve through hydraulic connection. This eliminates the need for separate unlock switches and complex electric control processes while maintaining enhanced safety.
3Reliability
If a gate lock lever and unlock switch are provided with electric components and controller, then safety is improved, but cost increases
Solution Approach 1:
The patent replaces the electric control system (unlock switch and controller) with a purely mechanical-hydraulic system. The gate lock lever mechanically operates the gate lock valve through direct hydraulic connection, eliminating the need for electric components and controllers. This substitution maintains the safety function while significantly reducing manufacturing costs and system complexity.
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 unintentional operations of the actuators, enhancing safety and reducing costs by simplifying the system and avoiding the need for expensive electric components, while allowing smooth operation when intended by the operator.
Implementation Method 1
a pilot pump (16) constituting a pilot hydraulic source together with a tank (12)
Implementation Method 2
a gate lock valve (27) provided between the pilot pump (16) and the pressure reducing valve type pilot valve (25) and switching the pressure in the pilot delivery line (23) to either one of a high pressure state by a delivery pressure of the pilot pump (16) or a low pressure state connected to the tank (12)
Implementation Method 3
a pressure reducing valve type pilot valve (25) connected to a pilot delivery line (23) of the pilot pump (16) and reducing a pressure of a pilot pressure oil supplied from the pilot delivery line (23) and outputting a pilot pressure to a directional control valve (20) on a main line side
Implementation Method 4
a throttle (32) disposed between the pilot pump (16) and the gate lock valve (27) and limiting a flowrate of the pilot pressure oil delivered from the pilot pump (16)
Implementation Method 5
a check valve (33) disposed between the gate lock valve (27) and the pressure reducing valve type pilot valve (25) and allowing a flow of the pilot pressure oil from the pilot pump (16) toward the pressure reducing valve type pilot valve (25) and shutting down the flow in an opposite direction
Data Source
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AI summary
A bypass line (35) having one end side connected to a pilot delivery line (23) between a pilot pump (16) and a throttle (32) and the other end side connected to the pilot delivery line (23) between a check valve (33) and a pressure reducing valve type pilot valve (25) so as to bypass the throttle (32), a gate lock valve (27), and the check valve (33) provided in order from a pilot pump (16) is provided in the pilot delivery line (23). A lock switching valve (36) shutting down a flow of a pilot pressure oil from the pilot pump (16) through the bypass line (35) at a normal time and allowing the flow of the pilot pressure oil through the bypass line (35) when a pressure generated in the pilot delivery line (23) exceeds a predetermined pressure between the gate lock valve (27) and the check valve (33) is provided in the bypass line (35).