Forklift Steering Actuator Structure to Limit Rod Deflection
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Solution Overview
Problem
Hydraulic steering systems in vehicles face inefficiencies due to power loss, low resolution, and frequent maintenance, necessitating a more reliable and compact alternative.
Innovation Solution
An electric actuator with a linear actuation unit, electric motor, and housing assembly, featuring a ball screw nut and bushings to minimize deflection and provide fixed end moments, enhancing the actuator's durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic motors and actuators are used in steering systems, then the system is relatively reliable and durable, but power loss occurs throughout the components causing the hydraulic system to lose efficiency
Solution Approach 1:
The patent replaces the hydraulic mechanical system with an electric actuator system. The electric motor directly drives the ball screw mechanism to convert rotational motion into linear motion for steering, eliminating hydraulic fluid power transmission and reducing energy loss throughout the system while maintaining reliability through direct mechanical coupling.
Solution Approach 2:
The patent extracts and removes the hydraulic components (motors, valves, actuators, and fluid power transmission elements) from the steering system, replacing them with an electric actuator. This extraction eliminates the sources of power loss associated with hydraulic fluid circulation, pressure drops, and component inefficiencies.
2Reliability
If hydraulic actuators are used in steering systems, then the system is durable, but low resolution and frequent maintenance are required
Solution Approach 1:
The patent replaces the complex hydraulic actuation system with a simpler electric actuator comprising an electric motor and ball screw mechanism. This substitution eliminates hydraulic seals, hoses, and fluid management components that require frequent maintenance, resulting in a more durable system with lower maintenance requirements.
Solution Approach 2:
The ball screw mechanism incorporates self-lubricating properties and the electric motor requires minimal intervention. The system is designed to operate autonomously without requiring frequent hydraulic fluid changes, seal replacements, or system bleeding, thereby reducing maintenance frequency and improving ease of repair.
3Speed
If hydraulic systems maintain on demand power at all times, then the system is responsive, but the hydraulic system becomes especially inefficient
Solution Approach 1:
The electric actuator operates periodically based on actual steering demands rather than maintaining continuous power. The electric motor activates only when steering input is detected, converting rotational motion to linear motion through the ball screw as needed, thereby eliminating the continuous power consumption and energy waste inherent in hydraulic systems that maintain pressure and flow readiness.
Solution Approach 2:
The electric actuator dynamically adjusts its operation to match actual steering requirements. The system transitions from a static hydraulic pressure maintenance mode to a dynamic electric motor control mode, where power is applied only when and where needed, optimizing both response speed and energy efficiency through real-time demand-based actuation.
4Loss of energy
If electric actuators with ball screw drive are used, then energy efficiency improves, but deflection of the actuator rod may increase
Solution Approach 1:
The actuator rod is constructed using composite materials or optimized alloy compositions that provide high strength-to-weight ratio and exceptional stiffness. This allows the rod to resist deflection under operational loads while maintaining the energy efficiency benefits of the electric ball screw drive system, effectively decoupling the stability issue from the energy efficiency improvement.
Solution Approach 2:
The patent addresses the deflection issue by reinforcing the actuator rod through additional structural dimensions, such as increasing the rod diameter or incorporating internal reinforcement structures. This dimensional enhancement increases the moment of inertia and flexural rigidity, reducing deflection without compromising the energy efficiency of the electric actuation system.
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
The electric actuator improves steering system efficiency and reliability by reducing deflection and maintaining a desired contact angle, extending the actuator's life and allowing greater turning angles while minimizing maintenance.
Implementation Method 1
The ball screw nut is arranged circumferentially around the actuator rod and configured to convert rotation of the ball screw nut into linear motion of the actuator rod
Data Source
AI summary
An electric actuator for a steering system is adapted to control an angle of steered wheels on a vehicle to adjust a direction of travel of the vehicle. The electric actuator includes a housing assembly, an electric motor, and an actuation unit. The housing assembly is arranged around the electric motor and the electric motor is coupled with the actuation unit and configured to cause an actuator rod of the actuation unit to move relative to the housing assembly.