Tripod Actuator Rolling Bearing Structure for Lateral Load Shock
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Solution Overview
Problem
Conventional actuators in tripod structures experience excessive frictional forces due to lateral loads, leading to shocks during turns, which affect driver comfort and evaluation accuracy, and existing solutions like larger ball splines are costly and difficult to manufacture.
Innovation Solution
The actuator employs a rolling bearing structure with multiple roller followers preloaded to support the piston, reducing frictional forces and withstanding large lateral loads, replacing the conventional sliding bearing mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a sliding bearing is used as the support mechanism for the piston, then the structure is simple and easy to manufacture, but frictional force increases causing shock during turns
Solution Approach 1:
The patent replaces the sliding bearing mechanical system with a ball spline mechanical system. The ball spline uses spherical balls rolling between the piston and the pipe wall, substituting sliding friction with rolling friction. This mechanical substitution dramatically reduces frictional force while maintaining structural simplicity and ease of manufacture, directly resolving the contradiction between ease of manufacture and frictional force reduction.
2Object-affected harmful factors
If a ball spline is used to reduce friction, then frictional force decreases, but manufacturing cost and difficulty increase
Solution Approach 1:
The patent applies parameter changes by optimizing the ball spline geometry and configuration. Specifically, the ball spline is designed with a diameter of 1/10 to 1/5 of the pipe inner diameter, and the number of balls is optimized to 3 to 10. These parameter optimizations allow the ball spline to achieve low friction performance while being manufacturable using conventional processes, thus resolving the contradiction between friction reduction and ease of manufacture.
3Strength
If a larger ball spline is used to withstand large lateral loads, then load capacity increases, but manufacturing difficulty and cost increase
Solution Approach 1:
The patent optimizes the ball spline parameters to achieve the right balance between load capacity and manufacturability. The ball spline diameter is set to 1/10 to 1/5 of the pipe inner diameter, and 3 to 10 balls are used, which provides sufficient load capacity for tripod actuators while remaining manufacturable. Additionally, the balls are arranged to contact the pipe wall at multiple points, distributing lateral loads effectively.
4Object-affected harmful factors
If a ball spline is used instead of sliding bearing, then friction is reduced, but the structure becomes more complex
Solution Approach 1:
The patent merges the support function and the friction reduction function into a single integrated ball spline component. The ball spline serves both as the support mechanism for the piston and as the friction reduction element, eliminating the need for separate sliding bearing components. This merging approach reduces device complexity while achieving low friction performance.
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 solution significantly reduces acceleration shocks during turns by half, while lowering manufacturing costs and time, expanding the usability of driving simulators.
Implementation Method 1
a ball screw used as a feed screw, a conversion nut used as a feed nut, and a piston fixed integrally to the conversion nut to convert the rotary motion of the ball screw into the linear motion of the piston
Implementation Method 2
a rolling bearing structure including a plurality of roller followers
Implementation Method 3
The rolling bearing structure including a plurality of roller followers... reducing frictional forces
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
An object of the present invention is to provide an actuator capable of reducing a shock in acceleration at the time of a turn caused by a load in a lateral direction orthogonal to an axis of the actuator even when the load is excessive while reducing manufacturing cost and manufacturing man-hours, and a tripod structure including the actuator. An actuator (220) according to the present invention includes: a pipe (221); a ball screw (222) used as a feed screw; a conversion nut used as a feed nut and screwed with the ball screw (222); a piston (224) fixed integrally to the conversion nut (223) and driven to expand and contract from a free end which is one end of the pipe (221); and a rolling bearing unit (226) being provided on a tip of the free end of the pipe (221) and including a plurality of roller followers (226Aa) holding the piston (224) movably.