Compact Power Steering Valve Design for Forklifts
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Solution Overview
Problem
Conventional power steering valves for forklifts are overdesigned when applied to small-capacity steering cylinders, leading to increased costs and equipment weight due to their large physical size, making it difficult to manufacture a compact version with the required performance.
Innovation Solution
A power steering valve design featuring a housing with specific flow paths, a cylindrically shaped sleeve and spool, and a gerotor with reduced diameter and increased eccentricity, where the drive shaft's length is within a defined range relative to the sleeve's length, allowing for a compact configuration that maintains performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the main body portion is made uniform in large-sized form to be applicable to large-capacity steering cylinders, then the power steering valve can satisfy the performance requirements for large-capacity steering cylinders, but the physical size becomes overdesigned when applied to small-capacity steering cylinders, leading to increased cost and equipment weight
Solution Approach 1:
The power steering valve is divided into a main body portion and a separate gerotor assembly. The main body portion is designed with a standardized interface that can accommodate different gerotor assemblies, allowing the same main body to serve both small-capacity and large-capacity steering cylinders by simply changing the gerotor assembly.
Solution Approach 2:
The gerotor assembly's parameters (such as diameter, number of lobes, and eccentricity) are varied to match different steering cylinder requirements. By changing these parameters while keeping the main body portion standardized, the valve can adapt to both small and large capacity applications without increasing overall size.
2Adaptability or versatility
If the main body portion is made uniform in large-sized form to be applicable to large-capacity steering cylinders, then the power steering valve can satisfy the performance requirements for large-capacity steering cylinders, but material cost increases due to overdesign for small-capacity applications
Solution Approach 1:
The valve is segmented into a main body portion and a gerotor assembly that can be separately manufactured and assembled. This allows the main body to be produced in standardized quantities at optimal production volumes, reducing per-unit manufacturing costs while the gerotor assembly can be customized as needed.
Solution Approach 2:
The main body portion is designed as a universal component that can be used with multiple different gerotor assemblies for different applications. This universality increases the production volume of the main body, economies of scale, and reduces material costs through more efficient manufacturing.
3Quantity of substance
If the gerotor diameter is increased to maintain hydraulic fluid ejection capacity for small-capacity steering cylinders, then the required ejection amount can be achieved, but the overall size of the power steering valve increases
Solution Approach 1:
Instead of increasing gerotor diameter, the design changes other parameters such as the number of lobes, eccentricity, and hydraulic fluid pressure to achieve the required ejection capacity. This allows maintaining compact size while still providing sufficient hydraulic fluid flow for small-capacity steering cylinders.
Data Source
AI summary
This power steering valve (1) includes a sleeve (40), a spool (60) held in such a way as to be able to rotate within the housing (40), to which an input shaft U of a steering wheel S is coupled, a gerotor (30) fixed to the sleeve (10) and configured to be driven by hydraulic fluid which flows out from the predetermined opening of the sleeve (40), and a drive shaft (80) meshing with an inner rotor (32) of the gerotor (30) and pivotally supported in a swingable manner by the sleeve (40) with use of a pin (81), wherein an overall length Ld of the drive shaft (80) is formed to have a dimension defined by (¼)·Ls≤Ld≤(½)·Ls relative to an overall length Ls of the sleeve (40), and the pin (81) is arranged at a position nearer the gerotor (30) in an axial direction than a middle position in the sleeve (40).