Hydraulic Involute Cam Actuator for Wide-Angle Manipulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydraulic manipulators using slider crank mechanisms are limited in motion to less than 120° and have nonlinear transmission ratios, requiring oversized actuators and complex, unreliable fluid pathways, which reduces efficiency and increases complexity.
Innovation Solution
A mechanical joint with a cam assembly and antagonistic actuators that rotate around a pivot axis, utilizing a curved surface with specific contact points and orthogonal distances to achieve linearly proportional torque and reduce friction, eliminating the need for pivoting actuators and flexible tubing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a slider crank mechanism is used to convert linear motion to rotational motion, then the mechanism can achieve rotational movement, but the motion is limited to less than 120° and the transmission ratio is nonlinear
Solution Approach 1:
The cam assembly is divided into multiple lobes (first lobe and second lobe) that independently engage with actuators, allowing each lobe to contribute to different portions of the rotational range. This segmentation enables the system to achieve a total rotation greater than 120° while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent employs curved cam surfaces with specific geometric profiles that guide the actuators through their range of motion. The curved surfaces are designed to provide the desired motion characteristics and transmission ratio properties without requiring complex linkage mechanisms.
2Force
If oversized actuators are used to compensate for nonlinear transmission ratio, then the torque requirement is met, but the efficiency of the hydraulic system is reduced
Solution Approach 1:
The cam profiles are designed with varying curvature and geometry along their surfaces, which changes the mechanical advantage (transmission ratio) at different positions in the rotation. This allows the system to maintain efficient force transmission throughout the range of motion without requiring oversized actuators, as the cam geometry compensates for transmission ratio variations.
3Ease of operation
If a pivoting actuator is used to compensate for circular motion of the crank center, then the mechanism can accommodate the motion, but flexible tubing or rotary unions are required which are less reliable and require more space
Solution Approach 1:
The invention extracts the pivoting function from the actuator itself and replaces it with a fixed-port actuator that moves linearly. The cam assembly absorbs the rotational and positioning functions, eliminating the need for the actuator to pivot and thereby removing the requirement for flexible tubing or rotary unions.
4Reliability
If the actuator is not allowed to pivot, then fluid pathways are simplified, but an extra linkage is required to compensate for circular crank motion which adds complexity and volume
Solution Approach 1:
The cam assembly merges multiple functions into a single component: it provides the motion conversion from linear to rotational, compensates for the circular motion of the crank center, and guides the actuator positions. This integration eliminates the need for separate compensating linkages, reducing overall system complexity and volume while maintaining reliability.
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
Enables efficient conversion of linear motion to rotational motion with a wider range of motion, linear torque application, reduced friction, and elimination of mechanical backlash, improving the efficiency and reliability of hydraulic systems.
Implementation Method 1
A first cam assembly is operatively secured to the first coupled member. The first cam assembly has a first lobe disposed on a first side of the first pivot axis and a second lobe disposed on a second side of the first pivot axis opposing the first side.
Implementation Method 2
The first and second actuators are configured to rotate the second coupled member with respect to the first coupled member through the plurality of first axis angular positions.
Implementation Method 3
The first lobe and the second lobe define a first curved surface having a first depression between the first lobe and the second lobe. Preferably the first curved surface is an involute surface.
Data Source
AI summary
Mechanical joints are provided in which the angle between a first coupled member and a second coupled member may be varied by mechanical actuators. In some embodiments the angle may be varied around a pivot axis in one plane and in some embodiments the angle may be varied around two pivot axes in two orthogonal planes. The joints typically utilize a cam assembly having two lobes with an involute surface. Actuators are configured to push against the lobes to vary the rotation angle between the first and second coupled member.