Hydraulic Sleeve Jacket Elastic Deformation
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Solution Overview
Problem
Hydraulic devices face issues with tight tolerances between pistons and sleeves, leading to a risk of scratching between the piston heads and sleeve jackets, especially near the sleeve bottom, due to asymmetric hydrostatic loads and radial deformation of the sleeve jacket.
Innovation Solution
A hydraulic device with a sleeve jacket having a relatively thin wall, allowing for low stiffness and elastic movability in the radial direction, which maintains constant radial deformation at the sealing line over a long distance, reducing the risk of contact and enabling tighter tolerances between the piston head and sleeve jacket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sleeve jacket has a larger wall thickness to increase stiffness, then the radial deformation at the sealing line decreases, but the risk of scratching between piston head and sleeve jacket increases near the sleeve bottom
Solution Approach 1:
The patent changes the wall thickness parameter of the sleeve jacket to be relatively thin, which fundamentally alters the stiffness characteristics. This parameter change allows the sleeve to have sufficient radial deformation capability at the sealing line while reducing the risk of scratching near the sleeve bottom, resolving the contradiction between sealing performance and scratching risk
Solution Approach 2:
The patent makes the sleeve jacket elastically movable in the radial direction with respect to the sleeve bottom, introducing dynamic flexibility to the system. This allows the sleeve to adapt its radial position based on operating conditions, maintaining optimal sealing contact while preventing harmful contact near the sleeve bottom
2Manufacturing precision
If the sleeve jacket has a thin wall to reduce stiffness, then the radial deformation at the sealing line remains constant over a long distance, but the sleeve becomes more susceptible to centrifugal forces at high rotational speeds
Solution Approach 1:
The patent introduces dynamic elasticity by making the sleeve jacket elastically movable with respect to the sleeve bottom. This dynamic characteristic allows the thin-walled sleeve to absorb centrifugal forces through elastic deformation rather than rigid resistance, maintaining manufacturing precision while mitigating the effects of high rotational speeds
Solution Approach 2:
The patent optimizes the wall thickness parameter to achieve a balance between stiffness and flexibility. The thin wall provides sufficient radial deformation capability for tight tolerances while the elastic movability compensates for the reduced stiffness at high rotational speeds
3Object-affected harmful factors
If the distance between sleeve bottom and sealing line is increased to reduce scratching risk, then the sleeve jacket has more space to deform, but the dead volume between sleeve bottom and top dead centre increases, reducing efficiency
Solution Approach 1:
The patent makes the sleeve jacket elastically movable in the radial direction, which allows the sealing line to maintain optimal proximity to the sleeve bottom without fixed geometric constraints. The elastic deformation dynamically adjusts the clearance, preventing scratching while maintaining minimal dead volume for high hydraulic efficiency
Solution Approach 2:
The patent changes the geometric parameter by allowing the sealing line position to vary dynamically through elastic deformation rather than being fixed by rigid geometry. This enables the system to maintain small dead volume while preventing scratching through controlled radial movement
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 minimizes the risk of scratching, maintains efficient operation by reducing leakage flow, and minimizes centrifugal forces, thus reducing noise and tilting of sleeves at high rotational speeds.
Implementation Method 1
the radial deformation of the sleeve jacket depends on the depth that the piston is inserted in the sleeve, but the radial expansion at the sealing line can almost be constant at different positions of the piston within the sleeve
Implementation Method 2
asymmetric hydrostatic load on the outer side of the piston head
Implementation Method 3
due to the asymmetric hydrostatic load on the outer side of the piston head, the thin-walled piston head deforms to an oval shape during the compression phase
Implementation Method 4
for hydraulic devices which are operated at high rotational speed centrifugal forces on the sleeves are minimized causing reduced tendency of the sleeves to tilt with respect to a barrel plate
Data Source
Figure 1~2
Figure 3~5
AI summary
A hydraulic device (1) comprises a housing (27), a shaft (2) which is mounted in the housing (27) and rotatable about a first axis of rotation (4), wherein the shaft (2) has a flange (8) extending transversely to the first axis (4), a plurality of pistons (9) which are fixed to the flange (8) at equiangular distance about the first axis of rotation (4), a plurality of cylindrical sleeves (10) including sleeve bottoms (12) and sleeve jackets (13), respectively, and cooperating with the pistons (9) to form respective compression chambers (11) of variable volume. The cylindrical sleeves (10) are rotatable about a second axis of rotation which intersects the first axis of rotation (4) by an acute angle such that upon rotating the shaft (2) the volumes of the compression chambers (11) change between bottom dead centre and top dead centre of the pistons (9) within the sleeves (10). Each piston (9) has a piston head (14) including a circumferential wall of which the outer side is ball-shaped, hence forming a sealing line within the cooperating sleeve jacket (13), and the inner side surrounds a cavity (21). Each sleeve jacket (13) has such a thin wall and/or is elastically movable with respect to the sleeve bottom (12) such that at a fixed pressure in the compression chamber (11) the radial deformation of the sleeve jacket (13) at the sealing line is substantially constant at piston positions ranging from bottom dead centre to a position where the distance between the sleeve bottom (12) and the sealing line is less than 50% of the distance between the sleeve bottom (12) and the sealing line at bottom dead centre.