Pneumatic Cylinder Holding Valve for Stable Clamping Force
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Solution Overview
Problem
Hydraulic cylinder devices experience a decrease in clamping force due to oil's lower compressibility compared to air, leading to pressure drops when pressurized oil leaks or temperature changes, causing operational state maintenance issues over time.
Innovation Solution
A pneumatic cylinder device using compressed air with a holding valve system that maintains pressure through a combination of air's higher compressibility and a biasing spring, ensuring the operational state is maintained for a longer period by closing the valve when air supply is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If pressurized oil is used in a hydraulic cylinder device, then the system can maintain high pressure, but the pressure drops when slight leakage occurs due to oil's low compressibility
Solution Approach 1:
The patent transitions from hydraulic (oil-based) to pneumatic (air-based) actuation. The pneumatic actuator uses compressed air which has high compressibility, allowing it to absorb pressure fluctuations and maintain stable operation even with minor leakage. This resolves the contradiction by replacing the fluid medium to inherently solve the pressure stability issue.
Solution Approach 2:
The patent changes the physical parameter of the actuation medium from incompressible (oil) to compressible (air). This parameter change allows the system to tolerate minor leakage without significant pressure loss, as the compressible air can compensate for volume loss through compression/expansion cycles, maintaining operational pressure and reliability.
2Duration of action of stationary object
If a holding valve is used to maintain pressure in the actuation chamber, then the operational state can be maintained, but the system complexity increases
Solution Approach 1:
The pneumatic actuator with compressible air serves its own pressure maintenance function through the inherent compressibility of air. When the supply valve closes, the compressed air in the chamber maintains pressure without requiring complex external holding mechanisms. The system uses its own operational medium's properties to maintain the lock state, reducing the need for additional complex components.
Solution Approach 2:
By using pneumatic principles with compressible air, the system achieves pressure maintenance through the physical properties of the gas rather than complex mechanical holding valves. The compressibility of air naturally provides pressure buffering and maintenance capabilities, simplifying the overall valve system while extending lock state duration.
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 pneumatic cylinder device effectively maintains operational state for a longer duration by minimizing pressure drops due to air's higher compressibility and utilizing the holding valve and spring to sustain pressure, outperforming hydraulic systems in maintaining clamping force.
Implementation Method 1
a first valve member (35) inserted in a first valve hole (33) so as to be movable, the first valve member (35) being biased by a first valve-closing spring (38) toward a first valve seat (34)
Implementation Method 2
air (compressed air) having a larger compressibility than that of oil is used as operating fluid. Due to this, in the pneumatic cylinder device of this aspect, even if compressed air contained in the first actuation chamber by the first holding valve leaks little by little to the outside of the first actuation chamber, decrease in pressure in the actuation chamber is smaller
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An output member (7) is inserted in a housing (5) so as to be movable in a left-right direction. A lock chamber (20) is provided to the right of the output member (7), as a first actuation chamber. Compressed air is supplied to and discharged from the lock chamber (20) through a first supply and discharge passage (24) provided in the housing (5). A first holding valve (30) provided to an intermediate portion of the first supply and discharge passage (24) is configured to close and open the first supply and discharge passage (24).