Propeller Shaft CV Joint Groove Design for Higher Slide Strength
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Solution Overview
Problem
The cross groove type constant velocity joint's strength is compromised when the slide amount increases, as the window portion of the cage widens, requiring both outer and inner race members to be reworked, leading to increased working costs.
Innovation Solution
A constant velocity joint design where only the inner race member is worked, featuring an outer race member with a cylindrical shape and a recessed outer race groove portion, a cage with a window portion, and an inner race member with a recessed inner race groove portion that intersects with the outer race groove, allowing the ball to fall into a smaller diameter recessed portion, maintaining strength without increasing window width and reducing working costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the window portion of the cage is increased in circumferential width to increase the slide amount, then the slide amount is increased, but the wall portions adjacent to the window portion are decreased in circumferential width, lowering the strength of the constant velocity joint
Solution Approach 1:
The ball is pre-positioned in a recessed portion of the inner race groove portion before operation. This recessed portion is formed in advance at the bottom of the inner race groove, allowing the ball to be retained at a specific position that enables increased slide amount while maintaining adequate wall portion dimensions for strength.
Solution Approach 2:
The inner race groove portion is given different local qualities: a recessed portion with smaller diameter is formed at the bottom, while the upper portion maintains its original diameter. This local variation allows the ball to be positioned lower, increasing the effective slide amount without compromising the overall structural integrity of the groove.
2Strength
If both the outer race member and inner race member are worked to prevent ball displacement, then the strength is maintained, but the working cost increases
Solution Approach 1:
The solution extracts the working operation from one component (outer race member) and concentrates it entirely on the other component (inner race member). By forming the recessed portion only in the inner race groove portion, the patent eliminates the need to work both components, thereby reducing working cost while maintaining strength through proper design of the recessed portion.
3Strength
If the ball is displaced from the slanted portion to the straight portion in the outer race groove portion to prevent strength reduction, then the strength is maintained, but both outer and inner race members must be worked, increasing working cost
Solution Approach 1:
Instead of preventing ball displacement by working both race members to create symmetric grooves, the patent inverts the approach by creating an asymmetric recessed portion in the inner race groove only. This allows the ball to naturally settle in the recessed portion without requiring symmetric working of both components, thereby maintaining strength while reducing manufacturing cost.
Data Source
AI summary
A constant velocity joint for a propeller shaft which is provided between a first propeller shaft and a second propeller shaft of a propeller shaft to connect the first propeller shaft and the second propeller shaft comprises an outer race member formed into a cylindrical shape, to which the first propeller shaft is connected, the outer race member including an outer race groove portion provided at an inner periphery of the outer race member in a recessed manner at a predetermined angle with respect to a rotational axis direction of the constant velocity joint; a ball member disposed in the outer race groove portion; a cage provided on an inner peripheral side of the outer race member and provided with a window portion that retains the ball member; and an inner race member provided on an inner peripheral side of the cage and connected to the second propeller shaft, the inner race member including an inner race groove portion provided at an outer periphery of the inner race member in a recessed manner so as to intersect with the outer race groove portion, the inner race groove portion in which the ball member is disposed; and a recessed portion formed on a second propeller shaft side in a bottom portion of the inner race groove portion to have a smaller diameter than rest of the bottom portion of the inner race groove portion.