Wobble Plate Variable Displacement Compressor Rotation Prevention
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Solution Overview
Problem
Conventional wobble plate type variable displacement compressors face issues with size, durability, noise, vibration, and cost due to the complexity of the rotation preventing mechanism, particularly with the Birfield type constant velocity universal joint, which struggles with uniform contact and increased play, leading to high contact pressure and weight.
Innovation Solution
A wobble plate type variable displacement compressor with a rotation preventing mechanism that uses an inner and outer ring with guide grooves and balls for power transmission, where the outer ring and wobble plate are connected via concave portions and plastic deformation, allowing for axial and rotational fixation, reducing the need for precise fitting and surface treatment, and optimizing the guide groove angles for uniform contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Birfield type constant velocity universal joint is used as a wobble plate rotation preventing mechanism, then the structure can support the wobble plate and swash plate, but the number of interposed parts increases and accumulated play becomes great, leading to insufficient vibration, noise and durability
Solution Approach 1:
The patent extracts and eliminates the cage component from the constant velocity universal joint structure. By removing the cage that holds the balls, the design reduces the number of interposed parts and eliminates the accumulated play between multiple components, directly addressing the reliability and durability issues while simplifying the overall structure.
Solution Approach 2:
The patent merges the functions of the inner ring, outer ring, and ball support structure into a more integrated configuration. The inner ring directly supports the main shaft, the outer ring supports the wobble plate, and the balls are positioned without requiring a separate cage, combining multiple supporting functions into a streamlined mechanism that reduces part count and improves durability.
2Power
If a Birfield type constant velocity universal joint is used with ball guide grooves, then rotational power transmission is achieved, but the contact surface between balls and guide grooves has large inclination, causing high contact load and requiring large ball size, making the structure difficult to make small-sized
Solution Approach 1:
The patent changes the geometric parameters of the guide grooves, specifically optimizing the inclination angles and curvature radii of the grooves on the inner and outer rings. This parameter optimization reduces the contact load on the balls, allowing for smaller ball sizes while maintaining sufficient power transmission ability, thereby reducing the overall structure weight and enabling compact design.
3Stability of the object's composition
If the inner ring is supported slidably in the axial direction with rotation prevention, then the main shaft must be made thick to ensure rigidity, causing increase of weight
Solution Approach 1:
The patent introduces spherical surfaces with optimized curvature radii at the contact points between the inner ring and main shaft, and between the outer ring and wobble plate. These curved contact surfaces distribute the load more effectively, providing the necessary rigidity and stability while allowing for a thinner, lighter main shaft design compared to flat or rigid supported structures.
4Device complexity
If cantilever supporting is employed for the rotational main shaft, then the structure is simplified, but whirling of the main shaft becomes great, being disadvantageous on durability, vibration and noise
Solution Approach 1:
The patent applies local quality optimization by introducing spherical contact surfaces with specific curvature radii at critical support locations. The inner ring has a spherical contact surface with a first curvature radius for supporting the main shaft, while the outer ring has a spherical contact surface with a second curvature radius for supporting the wobble plate. This localized curvature design provides enhanced stability and reduced whirling at the support points without requiring a completely complex support structure, thereby improving durability and vibration performance while maintaining reasonable structural simplicity.
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 design achieves a smaller, more durable, and quieter compressor with improved rotational balance, reduced weight, and lower manufacturing costs by ensuring uniform and continuous ball contact while minimizing play and contact pressure.
Implementation Method 1
a plurality of balls held by guide grooves formed on the inner ring and the outer ring at a condition of opposing each other and performing power transmission by being compressed between the guide grooves
Implementation Method 2
plastically deforming the other member partially at locations corresponding to the concave portions such that it fits into the concave portions, and fixing both members to each other in an axial direction and in a rotational direction by means of the plastic deformation
Data Source
AI summary
Disclosed is a wobble plate type variable displacement compressor that uses a constant velocity universal joint mechanism, which comprises an inner ring and an outer ring, balls that are held between guide grooves of the inner ring and the outer ring to transmit power, wherein a wobble plate is connected and fixed to the outer ring. In the compressor, the connecting structure for the outer ring and the wobble plate is formed by providing a plurality of concave portions arranged in a circumferential direction on one member, by plastically deforming the other member partially at locations corresponding to the concave portions such that it fits into the concave portions, and by fixing both members to each other in the axial direction and in the rotational direction by means of the plastic deformation. With this wobble plate type variable displacement compressor using the specified constant velocity universal joint mechanism, the structure for connecting the wobble plate and the outer ring in the wobble plate rotation preventing mechanism can be improved, thereby improving the productivity and reducing the cost and the weight.