Bent Axis Axial Piston Pump Center Shaft Segmentation
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Solution Overview
Problem
In bent axis type axial piston pumps/motors, the separation of the supporting end of the center shaft and piston rod from the drive shaft can lead to oil leakage and reduced strength of the retainer plate due to the need for a larger outer shape dimension and increased inner diameter of the shaft insertion hole, compromising the attachment load of the push spring.
Innovation Solution
The use of an outer race and inner shaft configuration with a push spring accommodated in a separate spring accommodation hole allows for a large attachment load without enlarging the outer shape dimension, ensuring the strength of the retainer plate and preventing separation of the supporting ends from the drive shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft portion of the center shaft is configured to have a thick diameter to apply the push spring having a large attachment load, then the oil leakage is reliably prevented, but the outer shape dimension of the supporting end needs to be formed large, which causes lowering in the strength of the retainer plate
Solution Approach 1:
The center shaft is divided into a shaft body and a separate supporting end portion. The supporting end portion is detached from the shaft body and fixed to the retainer plate, allowing the shaft body to maintain a thick diameter for push spring attachment while the supporting end portion can have optimized dimensions that do not compromise retainer plate strength.
Solution Approach 2:
A separate supporting end portion acts as an intermediary between the shaft body and the retainer plate. This intermediary component allows the push spring to be attached to the shaft body with large diameter while the supporting end portion maintains smaller dimensions that preserve retainer plate strength, thus mediating between the conflicting requirements.
2Force
If the inner diameter of the shaft insertion hole in the retainer plate is enlarged to accommodate the larger supporting end, then the push spring attachment load is increased, but the strength of the retainer plate is lowered
Solution Approach 1:
The supporting end is segmented from the shaft body and fixed to the retainer plate. This allows the shaft body to have large diameter for sufficient push spring attachment load while the supporting end portion has optimized dimensions that do not require enlarging the retainer plate hole, thus preserving retainer plate strength.
3Force
If the outer shape dimension of the supporting end is made larger, then the push spring can have larger attachment load, but the inner diameter of the shaft insertion hole needs to be enlarged, causing lowering in the strength of the retainer plate
Solution Approach 1:
The center shaft is segmented into shaft body and supporting end portion. The shaft body maintains large diameter for sufficient push spring attachment load while the supporting end portion is separate and has optimized dimensions that fit within the original retainer plate hole dimensions, preserving retainer plate strength.
Solution Approach 2:
The supporting end portion serves as an intermediary that transfers the push spring force from the shaft body to the retainer plate. This intermediary allows the shaft body to have large diameter for sufficient attachment load while the supporting end portion has smaller dimensions that do not compromise retainer plate strength.
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 configuration effectively prevents oil leakage between the valve plate and cylinder block while maintaining the strength of the retainer plate, ensuring reliable operation and enhanced volume efficiency.
Implementation Method 1
a push spring, which is arranged in the shaft attachment hole of the cylinder block to act to push the cylinder block against the valve plate
Implementation Method 2
A supporting end, which projects out from one end face of the cylinder block in the center shaft, and a supporting end, which projects out from one end face of the cylinder block in the piston rod, are each configured to have a spherical shape and are supported in a tiltable manner on one end face of the drive shaft
Data Source
AI summary
A center shaft of a bent axis type axial piston pump/motor includes an outer race, which is attached to a shaft attachment hole of a cylinder block, has a shaft portion accommodation hole at one end and has a spring accommodation hole at the other end, and an inner shaft, which includes a shaft supporting spherical head portion having a large outer shape dimension at a distal end of a shaft base portion and attached to the shaft portion accommodation hole of the outer race through the shaft base portion.