Compressible Crane Boom Stop Using Hydraulic Piston
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Solution Overview
Problem
Conventional boom stops for cranes face challenges in scaling up to accommodate larger cranes with higher capacities, as they require greater stopping force but are limited by physical space constraints, making it difficult to deploy larger spring and tube arrangements effectively.
Innovation Solution
A compressible stop member design featuring a housing with a free piston, a compressed gas chamber, and a rod support portion that separates the housing volume into liquid chambers, allowing for increased pressure and stopping force in a compact space, utilizing a hydraulic system integrated within the stop member without external connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a larger spring and tube arrangement is used to increase stopping force for high capacity cranes, then the stopping force increases, but the device size increases beyond available space
Solution Approach 1:
The patent applies hydraulic principles by using an incompressible fluid (hydraulic fluid) instead of a mechanical spring to transmit force. The hydraulic system allows force multiplication through pressure transmission, enabling compact design while achieving high stopping forces. The fluid-filled chamber with piston mechanism converts the boom's kinetic energy into hydraulic pressure, providing effective stopping force in a compact volume.
Solution Approach 2:
The patent changes the physical state and properties of the stopping mechanism from elastic deformation (spring) to hydraulic pressure (incompressible fluid). By utilizing the incompressibility parameter of hydraulic fluid, the system achieves much higher force density compared to spring-based systems, allowing the same stopping force to be generated in a significantly smaller volume.
2Device complexity
If a conventional spring-based boom stop is used, then the design is simple, but it cannot be easily scaled up for larger cranes with higher capacities
Solution Approach 1:
The patent replaces the simple spring mechanism with a hydraulic system that uses incompressible fluid to generate stopping force. This hydraulic approach provides superior force capacity and scalability while maintaining relatively simple construction. The system uses a piston, fluid-filled chamber, and basic mechanical components to achieve high stopping forces suitable for large capacity cranes.
Solution Approach 2:
The patent segments the stopping mechanism into distinct functional components: a piston element, a fluid-filled chamber, and a housing structure. This segmentation allows for modular design and scaling, where the same basic hydraulic principle can be applied to different size cranes by adjusting the chamber volume and piston dimensions without fundamentally changing the design approach.
3Force
If external hydraulic connections are used to provide stopping force, then sufficient force can be generated, but the system becomes complex and requires external connections
Solution Approach 1:
The patent implements a self-contained hydraulic system where the boom stop generates its own stopping force using the kinetic energy of the boom itself. The system automatically converts the boom's forward momentum into hydraulic pressure through the piston-chamber mechanism, eliminating the need for external hydraulic power sources, control valves, or external connections. The boom's own motion drives the hydraulic pressure generation.
Solution Approach 2:
The patent merges the stopping function with the structural components of the boom stop assembly. The hydraulic chamber, piston, and housing are integrated into a single compact unit that serves both as the stopping mechanism and as a structural element. This consolidation eliminates separate external hydraulic systems and reduces overall system complexity.
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 enables the generation of large stopping forces and energy absorption in a compact format, effectively preventing crane components from tipping over, while eliminating the need for external hydraulic connections, thus simplifying the system and reducing costs.
Implementation Method 1
A compressible stop member... includes an accumulator... a compressed gas chamber in the housing between the free piston and the first sealed end
Implementation Method 2
The rod support portion separates the volume between the free piston and the second end of the housing not occupied by the rod into first and second liquid chambers
Data Source
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AI summary
A compressible stop member for use on a crane (10) includes: a) a housing (52) having a first sealed end (54), a second end (56) and an internal surface (53) comprising a first cylindrical surface and a second cylindrical surface; b) a free piston (62) slidably contained within the housing (52) in a sealing engagement with the first cylindrical surface; c) a compressed gas chamber (58) in the housing (52) between the free piston (62) and the first sealed end (54); and d) a rod (76) comprising a cylindrical portion with a diameter less than the diameter of the second cylindrical surface and a rod support portion (64). The rod (76) extends out of the second end (56) of the housing (52) with a sliding sealing engagement. The rod support portion (64) is slidably contained within the housing (52), and separates the volume between the free piston (62) and the second end (56) of the housing into a first liquid chamber (57) comprising the volume inside the housing (52) between the free piston (62) and the rod support portion (64), and a second liquid chamber (59) comprising the space between the rod support portion (64) and the second end (56) of the housing (52). Also, the rod support portion (64) includes at least one flow channel (65) allowing liquid to flow between the first and second liquid chambers (57, 59) as the rod support portion (64) slides within the housing (52). The compressible stop member is particularly useful as a boom stop (15) for a lift crane (10) having a boom (22) pivotally mounted on a rotating bed (20). The boom stop (15) will engage the boom (22) when the boom (22) reaches a first angle compared to the plane of rotation of the rotating bed (20). Movement of the boom (22) from the first angle to a second steeper angle causes the rod (76) to be pushed into the housing (52), thereby forcing the rod support (64) toward the free piston (62), with liquid flowing from the first liquid chamber (57) into the second liquid chamber (59) as the rod (76) travels, creating an increased volume in the second liquid chamber (59) but a decreased volume in the first liquid chamber (57) and a commensurate increase in pressure in the gas chamber (58) and on the rod support (64), thereby impeding the movement of the boom (22) towards the second steeper angle. If the lift crane (10) includes a luffing jib (23), a separate compressible stop member may also be used as a jib stop (45).