Rotary Hydraulic Pump Capacity Control Without Axial Cam Movement
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Solution Overview
Problem
Existing variable capacity hydraulic rotating machines are bulky due to the need for a mechanism to move a cam ring in the axial direction, increasing their size in both axial and radial directions.
Innovation Solution
A hydraulic rotating machine design that includes a housing, cylinder block, pistons, port block, and cam ring, with a capacity changing unit that adjusts the relative positional relation between the port block and cam ring by rotating them about the rotation center axis, allowing for variable capacity without increasing the machine's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cam ring is moved in the axial direction to change pump capacity, then the pump capacity becomes variable, but the pump size increases in both axial and radial directions
Solution Approach 1:
The invention changes the dimension of cam ring movement from axial direction to rotational direction about the rotation center axis. The capacity changing unit rotates the cam ring about the rotation center axis instead of moving it axially, thereby achieving variable capacity without increasing the pump size in axial or radial directions. This dimensional transformation resolves the contradiction between variable capacity and compact size.
2Adaptability or versatility
If a mechanism is added to move the cam ring axially, then the pump capacity becomes variable, but the device complexity increases
Solution Approach 1:
The cam ring serves multiple functions: it maintains radial positioning of pistons through its cam surface and simultaneously enables capacity variation through rotation about the rotation center axis. The capacity changing unit integrates the functions of capacity control and cam ring actuation. This multi-functionality reduces device complexity while achieving variable capacity.
3Reliability
If the cam ring is positioned on the outer side radially, then the piston can contact the cam surface, but the pump size increases in the radial direction
Solution Approach 1:
The invention changes the capacity adjustment mechanism from axial movement to rotational movement about the rotation center axis. The cam ring rotates about the rotation center axis to vary capacity, eliminating the need for additional radial space. This maintains reliable piston-cam contact while keeping the radial size compact.
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
The design achieves a compact variable capacity hydraulic rotating machine by optimizing the placement of components, enabling efficient fluid flow management without enlarging the machine's dimensions.
Implementation Method 1
a capacity changing unit configured to change an amount of the working fluid guided into the capacity chamber by causing at least one of the port block and the cam ring to rotate about the rotation center axis and changing a relative positional relation between the port block and the cam ring
Implementation Method 2
a plurality of pistons slidably inserted into the cylinders and defining respective capacity chambers inside the cylinders
Implementation Method 3
a cam ring having a cam surface with which a tip of the piston comes into contact as the cylinder block rotates
Data Source
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AI summary
A pump (100) includes: a cylinder block (30) configured to rotate together with a shaft (20); a piston (36) that is slidably inserted into a cylinder (31) formed in the cylinder block (30); a port block (50) having a first port (41) through which a working fluid supplied to a capacity chamber (32) flows and a second port (45) through which a working fluid discharged from the capacity chamber (32) flows; a cam ring (60) having a cam surface (61); and a capacity changing unit (70) configured to change an amount of the working fluid guided into the capacity chamber (32) by causing the port block (50) to rotate about a rotation center axis (C1) and changing a relative positional relation between the port block (50) and the cam ring (60).