Tripod Actuator Structure Using Linear Bearings to Minimize Shock
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Solution Overview
Problem
Existing actuators in driving simulators experience acceleration shocks during piston reciprocation, making it difficult to accurately evaluate vehicle body models due to frictional forces that increase with piston stroke, leading to ambiguity in whether the shock is from the vehicle model or the vibration devices.
Innovation Solution
The actuator incorporates a tripod structure with a piston, ball screw shaft, and linear motion bearing units, which are eccentrically arranged to reduce frictional forces by transitioning from sliding to rolling friction, thereby minimizing acceleration shocks. This includes a cylinder supported by a drive motor, a piston, a ball screw shaft, and linear motion bearing units that support the piston and slide block movably, reducing frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sliding bearings and nut guides are used to support the piston, then the actuator structure is simple, but frictional forces increase with piston stroke amount causing acceleration shocks
Solution Approach 1:
The patent replaces sliding friction-based mechanical support (sliding bearings and nut guides) with rolling friction-based support (linear motion bearing units with rolling elements). This substitution reduces frictional forces to about 1/10 of conventional systems, eliminating acceleration shocks while maintaining structural simplicity
Solution Approach 2:
The patent changes the friction parameter by transitioning from sliding friction to rolling friction through the use of linear motion bearing units. This parameter change reduces frictional resistance significantly, allowing the piston to reciprocate smoothly without generating acceleration shocks
2Length of moving object
If the piston stroke amount is increased, then the vibration device performance is improved, but frictional forces increase causing measurement ambiguity
Solution Approach 1:
By replacing sliding bearings with linear motion bearing units that use rolling elements, the patent reduces frictional forces to about 1/10 of conventional systems. This allows for larger piston strokes without generating acceleration shocks, thereby maintaining measurement precision in vehicle body model evaluations
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 solution effectively reduces acceleration shocks by minimizing frictional resistance to about 1/10 of conventional systems, allowing for more accurate evaluation of vehicle body models by distinguishing between vehicle model and vibration device-induced shocks.
Implementation Method 1
linear motion bearing units which support the piston and the slide block movably with each other, thereby minimizing frictional resistance
Implementation Method 2
a ball screw shaft (66) located in the cylinder (50a) and driven by the drive motor (32C)
Data Source
Figure 1
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AI summary
An actuator 38C includes a cylinder 50 sandwiched between a fixing plate 70 fixed to the other end surface of a supporting plate 34C together with a servomotor 32C and a bearing housing 52, a ball screw shaft 66 having one end protruding into the cylinder 50 through through holes of the fixing plate 70, a slide block 62 screwed with one end of the ball screw shaft 66 in the cylinder 50, a cylindrical-shaped piston 54 coupled to an end of the slide block 62 and reciprocatably located in the cylinder 50, linear motion bearing units 56AF and 56BF located inside the bearing housing 52 to movably support the piston 54, and linear motion bearing units 64A and 64B located in the cylinder 50 to movably support the slide block 62.