Forklift Hydraulic Control Device for Simultaneous Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic control devices for forklift trucks face challenges in simultaneously operating multiple loading members at their respective instructed speeds, as they often require a single hydraulic pump to manage multiple operations efficiently.
Innovation Solution
A hydraulic control device with a first hydraulic cylinder for lifting and lowering forks, a second hydraulic cylinder for a hydraulically-operated unit, a hydraulic pump driven by an electric motor, a lowering control valve, a flow rate control valve, and a controller that adjusts the electric motor's rotation speed based on operation instructions to manage the hydraulic pump's speed during simultaneous operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic pump is used to operate multiple loading members, then the device complexity is reduced, but the ability to operate multiple loading members at their respective instructed speeds deteriorates
Solution Approach 1:
The patent implements dynamic priority assignment where the controller dynamically determines which loading member has priority based on current operational conditions. The priority can be changed during operation, allowing the system to adapt to different work scenarios. This dynamic control enables a single hydraulic pump to serve multiple loading members effectively by switching priority based on operational needs.
Solution Approach 2:
The controller adjusts the rotation speed of the hydraulic pump based on the priority loading member's requirements. By changing the pump's rotation speed parameter dynamically, the system can optimize performance for the priority loading member while still providing hydraulic fluid to other members, enabling flexible operation with a single pump.
2Stability of the object's composition
If the hydraulic pump rotation speed is restricted to prevent abrupt changes, then the operational stability is improved, but the ability to respond to high-speed operation instructions deteriorates
Solution Approach 1:
The controller performs preliminary assessment of operation instructions before executing pump speed changes. It evaluates whether a speed change is necessary and appropriate based on current system state, then executes controlled adjustments. This preliminary control prevents unnecessary abrupt changes while still enabling timely responses to genuine operational needs.
Solution Approach 2:
The system implements feedback control where the controller continuously monitors the actual rotation speed of the hydraulic pump and compares it with the target speed. Based on this feedback, the controller adjusts the pump speed incrementally, preventing abrupt changes that would cause instability while still achieving the desired operational speed when needed.
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
Enables smooth and efficient operation of multiple loading members by restricting the hydraulic pump's rotation speed to prevent abrupt changes, ensuring each operation is performed at a stable speed, thereby improving the overall operational efficiency of the forklift truck.
Implementation Method 1
a hydraulic pump that supplies hydraulic oil to the first hydraulic cylinder and the second hydraulic cylinder
Implementation Method 2
a lowering control valve that is disposed in the first passage and allows flow of hydraulic oil from the first hydraulic cylinder toward the hydraulic pump while the forks are being lowered and that blocks the flow of hydraulic oil from the first hydraulic cylinder toward the hydraulic pump while the forks are being lifted or at a stop
Implementation Method 3
a flow rate control valve that is disposed in the drain passage and controls a flow rate of hydraulic oil
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
A hydraulic control device of a forklift truck (11) includes a first hydraulic cylinder (14), a first instruction member (22), a second hydraulic cylinder (19, 25), a second instruction member (23, 45), a hydraulic pump (30), an electric motor (31), a first passage (K1) which has a drain passage (K2), a lowering control valve (32) that controls flow of hydraulic oil, a flow rate control valve (35), and a controller (S). When a lowering operation of forks (16) and an operation of a hydraulically-operated unit (13) are performed simultaneously, when a required rotation speed of the hydraulic pump that is required for operating the hydraulically-operated unit at an instruction speed based on an operation of the second instruction member is a specified rotation speed or lower, the controller controls an instruction rotation speed of the electric motor so as to operate the hydraulic pump at the required rotation speed to thereby restrict the operation of the hydraulic pump.