Forklift Hydraulic Sequence Control for Load Handling
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Solution Overview
Problem
Existing forklifts require extensive training and user attention to coordinate primary and secondary tilting motions for load handling, leading to fatigue and error-prone operations due to complex hydraulic systems with separate control elements.
Innovation Solution
A forklift with a hydraulic sequence control system that prioritizes the secondary tilting motion of the fork carriage over the primary tilting motion of the mast, using a single operating element to simplify control and reduce complexity, allowing coordinated load handling through a hybrid system of electronically and mechanically switched valves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate operating elements are used to control primary and secondary tilting motions independently, then the hydraulic system can provide flexible control for each motion, but the user must coordinate multiple operating elements which increases complexity and reduces ease of operation
Solution Approach 1:
The patent combines control of the primary tilting motion (mast) and secondary tilting motion (fork carriage) into a single operating element. When the user actuates this single element, the hydraulic system automatically executes a coordinated sequence: first tilting the fork carriage to an inclined position, then tilting the mast to an inclined position. This merging of control functions eliminates the need for the user to coordinate multiple separate operating elements, significantly improving ease of operation while the hydraulic system manages the complexity of coordinating both motions.
2Ease of operation
If a single operating element controls both primary and secondary tilting motions, then the control process is simplified and user fatigue is reduced, but the hydraulic system must implement sequence control logic to coordinate the motions
Solution Approach 1:
The hydraulic system is configured to execute preliminary actions in a predetermined sequence when a single operating element is actuated. First, the system tilts the fork carriage to an inclined position before tilting the mast. This preliminary sequencing is built into the hydraulic circuit design, allowing the complex coordination logic to be embedded in the system rather than requiring complex electronic controls or user coordination skills.
Solution Approach 2:
The hydraulic system acts as an intermediary between the user's single operating element input and the two tilting motions. The hydraulic circuitry translates the single user input into coordinated actuation of both the fork carriage tilt mechanism and the mast tilt mechanism, managing the complexity of sequence control within the hydraulic system itself rather than requiring complex external control systems.
3Reliability
If the secondary tilting motion is prioritized over the primary tilting motion, then load handling safety is improved by ensuring the fork carriage is properly positioned, but the hydraulic system requires sequence control mechanisms to enforce this priority
Solution Approach 1:
The hydraulic sequence control ensures that the secondary tilting motion of the fork carriage is executed as a preliminary action before the primary tilting motion of the mast begins. When the user actuates the single operating element, the system first tilts the fork carriage to the inclined position, ensuring proper load engagement and positioning, before subsequently tilting the mast. This built-in sequencing prioritizes the safety-critical fork carriage positioning while managing system complexity through hydraulic circuit design rather than complex electronic control.
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 enhances operability by reducing user fatigue and error, ensuring safe and efficient load handling by prioritizing the secondary tilting motion, thus simplifying the control process and improving overall forklift performance.
Implementation Method 1
The mast is tiltable by a hydraulically generated force acting between the chassis and the mast. The fork carriage is tiltable by a hydraulically generated force acting between the fork carriage and the mast.
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
Forklift (1) comprising: - a chassis (2) - a mast (40) hydraulically tiltable relative to the chassis (2) in a primary tilting motion at least between a substantially upright position and at least one inclined position - a fork carriage (50) for mounting forks (54) for supporting a load (5), the fork carriage (50) being hydraulically tiltable relative to the mast (40) in a secondary tilting motion at least between a position in which the fork carriage (50) is substantially aligned with the mast (40) and at least one position in which the fork carriage (50) is inclined relative to the mast (40) - a hydraulic system having at least one operating element (33) for a user to control the primary tilting motion and the secondary tilting motion wherein the hydraulic system is configured to carry out a hydraulic sequence control of the primary tilting motion and the secondary tilting motion, wherein for picking up a load (5), upon actuation of one operating element (33), the secondary tilting motion from the position in which the fork carriage (50) is substantially aligned with the mast (40) to at least one position in which the fork carriage (50) is inclined relative to the mast (40) is carried out before the primary tilting motion from the substantially upright to the at least one inclined position for setting down a load, upon actuation of one operating element (33) the secondary tilting motion from the at least one position in which the fork carriage (50) is inclined relative to the mast (40) to the position in which the fork carriage (50) is substantially aligned with the mast (40) is carried out before the primary tilting motion from the at least one inclined position to the substantially upright position, wherein the primary tilting motion from the at least one inclined position to the substantially upright position is hydraulically locked until the fork carriage (50) is substantially aligned with the mast (40).