Hydraulic Cylinder Buffer Sleeve Segmentation for Reliability
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Solution Overview
Problem
Hydraulic cylinders with large diameters and long strokes face challenges in high-load, high-frequency operations due to precise manufacturing requirements and mechanical failures, such as the big buffer sleeve failing to insert into the buffer inner hole, leading to potential piston rod tilting and reduced production capacity.
Innovation Solution
A hydraulic cylinder design featuring axially slidable buffer sleeves with sealing end faces and throttle oil channels, including circumferential balancing oil grooves and a return spring, which form variable sealing surfaces and throttle areas to achieve smooth and reliable buffering, reducing manufacturing precision needs and preventing mechanical failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a big buffer sleeve and buffer inner hole with precise fit clearance are used for buffering, then the buffering effect is improved, but the manufacturing precision requirement becomes extremely high and the reliability decreases due to failure to insert under high load and high frequency operations
Solution Approach 1:
The buffer mechanism is divided into multiple segments: a buffer sleeve with a buffer outer surface, and a buffer hole with a buffer inner surface. The buffer sleeve is segmented into multiple buffer segments along the axial direction, each with varying fit clearances. This segmentation allows different portions of the buffer sleeve to have different clearance characteristics, enabling reliable buffering while reducing overall manufacturing precision requirements.
Solution Approach 2:
Different fit clearances are applied to different local regions of the buffer sleeve. Specifically, the buffer sleeve has a first fit clearance in a first region and a second fit clearance in a second region, where the clearances differ. This local quality approach ensures that critical areas have the necessary precision while other areas can be manufactured with lower precision, thus resolving the contradiction between buffering effectiveness and manufacturing feasibility.
2Manufacturing precision
If the fit clearance between buffer sleeve and buffer inner hole is made very small for precise buffering, then the buffering precision is improved, but the ease of operation deteriorates as the piston rod tilts under gravity and the buffer sleeve fails to insert
Solution Approach 1:
The buffer mechanism transitions from a static fit clearance design to a dynamic one where the buffer sleeve can move axially. The varying fit clearances along the axial direction allow the buffer sleeve to dynamically adjust its position and clearance during operation. This dynamic design ensures easy insertion while maintaining precise buffering when engaged, resolving the contradiction between insertion ease and buffering precision.
Solution Approach 2:
The buffer sleeve is designed with larger fit clearances in regions that engage first during insertion, allowing easy initial engagement. As the piston rod continues to move, subsequent regions with smaller clearances engage to provide precise buffering. This preliminary action approach ensures that insertion is easy while最终 achieving precise buffering effect.
3Device complexity
If compression spring is used as buffer device for small cylinders, then the device complexity is reduced, but the reliability deteriorates for large diameter and long stroke cylinders where sufficient elasticity cannot be obtained
Solution Approach 1:
The invention uses hydraulic oil pressure instead of mechanical spring compression to achieve buffering. The buffer hole communicates with the rod cavity, allowing hydraulic oil to be compressed and throttled during buffer engagement. This hydraulic approach provides reliable buffering for large diameter and long stroke cylinders without the complexity of designing oversized springs with sufficient elasticity.
Solution Approach 2:
The buffering mechanism changes from relying on spring material properties and geometry to relying on hydraulic oil compressibility and flow resistance. By changing the parameter from solid spring elasticity to fluid compressibility and throttling, the system achieves reliable buffering for large-scale applications where spring-based solutions become impractical.
4Reliability
If a hydraulic buffering mechanism with precise fit clearance is used for large diameter and long stroke cylinders, then the buffering effect is improved, but the productivity deteriorates due to excessive manufacturing precision requirements that restrict production capacity
Solution Approach 1:
The buffer sleeve is segmented into multiple regions with different fit clearances, allowing manufacturers to focus precision requirements on specific critical regions rather than the entire buffer sleeve. This segmentation reduces overall manufacturing complexity and enables higher production capacity while maintaining effective buffering.
Solution Approach 2:
By applying different fit clearances to different local regions of the buffer sleeve, the invention allows manufacturers to use lower precision manufacturing processes for non-critical regions while maintaining high precision only where necessary. This local quality approach significantly reduces manufacturing costs and increases production capacity for large diameter and long stroke hydraulic cylinders.
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 ensures reliable buffering, extended service life, and simplified manufacturing for hydraulic cylinders with large diameters and long strokes, preventing mechanical failures and enhancing production capacity by providing smooth and effective deceleration and braking.
Implementation Method 1
a throttle oil channel is formed by a clearance between the big buffer sleeve 04 and the buffer inner hole 07... the piston 05 can continue to perform movement in the extending direction, but its movement is slowed down due to the damping effect of the throttle oil channel
Implementation Method 2
The snubber, at a predetermined position of piston movement traps a quantity of working fluid placing the orifice intermediate the rapped fluid and the fluid discharge
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present application discloses a hydraulic oil cylinder, of which a piston rod (3) is provided with at least two cushion collars (4, 11) which are axially slidable along the piston rod (3). Axial throttle oil channels (301a, 301b) are provided between the cushion collars (4, 11) and a piston (6). A first cushion collar (4) is provided with a sealing end face (401), and an end cover of a rod cavity (1) is provided with a sealing end face (101). The sealing end face (401) of the first cushion collar contacts with the sealing end face (101) of the end cover of the rod cavity to form a seal. Hydraulic oil within the rod cavity is discharged through one axial throttle oil channel (301a) to an oil passage B. A second cushion collar (11) is provided with a sealing end face (111), and an end cover of a rodless cavity (12) is provided with a sealing end face (121). The sealing end face (111) of the second cushion collar contacts with the sealing end face (121) of the end cover of the rodless cavity to form a seal. Hydraulic oil within the rodless cavity is discharged through another axial throttle oil channel (301b) to another oil passage A. The hydraulic oil cylinder can operate reliably and achieve a buffer function in a large load, high frequency operating condition, and thus has a longer operating life. And also, precision requirements for manufacturing the hydraulic oil cylinder are low, thereby facilitating production of the hydraulic oil cylinder. The present application also discloses a hydraulic cushion system, an excavator and a concrete pump truck which use the above hydraulic oil cylinder.