Ring Cam Segment Intersecting Surfaces for Radial-Piston Hydraulic Machines
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Solution Overview
Problem
In radial-piston type hydraulic machines with ring cams, piston rollers often experience abrasion due to non-smooth transitions between cam segments, leading to inefficiencies and potential damage.
Innovation Solution
The design incorporates a configuration where the first cam surface of the preceding segment is closer to the piston assembly than the second cam surface, with both surfaces intersecting in an engagement region, allowing for smooth transition and accommodating misalignment, while also featuring convex curved surfaces and specific intersection points to enhance smoothness and machining tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piston rollers transit between cam segments in a coupling region, then the ring cam can be assembled from multiple segments, but abrasion occurs on piston rollers or cam surfaces due to non-smooth transition
Solution Approach 1:
The patent applies curvature by designing the first and second cam surfaces as intersecting curved surfaces rather than flat surfaces. The first cam surface on the preceding segment and the second cam surface on the following segment are configured to intersect smoothly, creating a continuous curved transition path for the piston roller. This curved surface design eliminates abrupt transitions and ensures smooth roller movement between segments, preventing abrasion while maintaining segment assembly capability.
2Strength
If cam segments are coupled with engagement portions, then the ring cam can maintain structural integrity, but misalignment between segments may occur causing transition issues
Solution Approach 1:
The patent employs asymmetric design in the engagement portions, where the first engagement portion on the preceding segment and the second engagement portion on the following segment have complementary asymmetric geometries. This asymmetric configuration creates a self-aligning mechanism that guides the segments into proper relative positions during assembly, automatically compensating for minor manufacturing tolerances and preventing misalignment issues while maintaining structural integrity.
3Reliability
If the first cam surface is disposed closer to the piston assembly than the second cam surface, then smooth transition is achieved, but the configuration becomes more complex
Solution Approach 1:
The patent merges the transition function into the existing cam surface geometry by integrating the first and second cam surfaces as continuous intersecting surfaces on the engagement portions. Rather than adding separate transition mechanisms or components, the solution combines the cam profile design with the segment engagement structure, allowing the same cam surfaces to simultaneously provide both the driving action and the smooth transition between segments, thereby minimizing additional complexity.
Data Source
Figure 1
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Figure 3A~3B
AI summary
A hydraulic machine of a radial-piston type includes: a rotor shaft extending in an axial direction of the hydraulic machine; a ring cam extending in a circumferential direction of the hydraulic machine and configured to rotate together with the rotor shaft; and a piston assembly configured to perform reciprocating motion in accordance with rotation of the ring cam. The ring cam comprises a plurality of cam segments arranged in the circumferential direction. At least one adjacent pair of the plurality of cam segments includes a preceding segment and a following segment disposed subsequent to the preceding segment in a rotational direction of the ring cam. The preceding segment has a first engagement portion protruding toward the following segment at a trailing end portion of the preceding segment. The following segment has a second engagement portion protruding toward the preceding segment at a leading end portion of the following segment and being engageable with the first engagement portion of the preceding segment. The first engagement portion has a first cam surface facing the piston assembly, in the trailing end portion of the preceding segment, and the second engagement portion has a second cam surface facing the piston assembly, in the front end portion of the following segment, the second cam surface. The first cam surface is disposed closer to the piston assembly than the second cam surface with respect to a radial direction of the hydraulic machine at a front end of the second cam surface. The first and second cam surfaces intersect each other in an engagement region of the first and second engagement portions.