Firefighting Nozzle Trigger Valve with Four-Bar Linkage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Firefighting nozzles with high flow rates and pressures require significant manual force to operate, exceeding the physical limits of firefighters, and existing trigger valves are unsuitable for larger sizes due to increased operational forces and water hammer risks, making it difficult to scale up for effective firefighting.
Innovation Solution
A trigger-operated slide valve nozzle design that allows one-handed operation with reduced opening forces, incorporates a locking mechanism for safety, and features a pistol grip with adjustable stroke length and dampening mechanism to manage water hammer, ensuring comfortable operation and control under high pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If trigger valve size is increased to achieve higher flow rates, then firefighting effectiveness is improved, but operational force required exceeds finger muscle capacity
Solution Approach 1:
A lever arm mechanism acts as an intermediary between the trigger and valve stem. The lever arm amplifies the force applied by the trigger, allowing small finger forces to control larger valve elements required for high flow rates. The lever arm rotates about a pivot point and translates trigger motion into amplified linear motion at the valve stem connection point.
2Speed
If valve closing speed is increased to enable rapid on/off control, then responsiveness is improved, but water hammer effects increase causing hose rupture risk
Solution Approach 1:
The valve system incorporates adjustable closing characteristics that allow dynamic control of the closure process. The lever arm mechanism and trigger geometry can be designed to provide different closing speeds, including controlled deceleration near the closed position. This dynamic control enables rapid valve operation while reducing water hammer effects through managed deceleration of the water column.
3Ease of operation
If lever handle is replaced with trigger to enable one-handed operation, then ease of operation is improved, but mechanical advantage is reduced requiring four times more force
Solution Approach 1:
The trigger mechanism utilizes rotational motion in a different dimensional plane compared to traditional linear lever handles. By converting the linear pull motion of a lever into a rotational squeezing motion of the trigger, the system achieves one-handed operation while the lever arm mechanism provides the necessary force amplification in the valve control dimension.
4Quantity of substance
If valve element size is increased to handle higher flows, then flow capacity is improved, but frictional forces and seal drag increase making operation difficult
Solution Approach 1:
The lever arm mechanism serves as a force-amplifying intermediary that compensates for increased frictional forces and seal drag on larger valve elements. By providing mechanical advantage, the system enables adequate sealing forces on large valve elements to be achieved with manageable trigger operating forces, maintaining one-handed operability despite larger valve sizes.
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
Enables comfortable and safe operation of high-flow firefighting nozzles with reduced physical strain on firefighters, minimizing water hammer risks and allowing for precise control of water flow, thereby enhancing firefighting effectiveness and safety.
Implementation Method 1
nearly instantaneous deceleration of a large water mass produces significant water hammer which carries risks such as injury from catastrophic hose rupture
Implementation Method 2
features a pistol grip with adjustable stroke length and dampening mechanism to manage water hammer
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A firefighting nozzle comprises an elongated barrel having a inlet opening at one end for engaging a source of fluid under pressure and a discharge opening at an opposite end for engaging a discharge element for dispensing the fluid under pressure. A valve arrangement includes a slide valve element slidably mounted within the barrel for reciprocating movement along the length of the barrel to adjust the flow of fluid through the barrel. The nozzle includes a pistol grip trigger assembly mounted on the barrel that includes a segment gear pivotably for engaging a toothed surface of the slide valve element so that rotation of the segment gear causes reciprocation of the slide valve element. A four-bar linkage arrangement is incorporated between a manually actuated trigger to translate depressing the trigger to controllable reciprocation of the slide valve element. The four-bar linkage provides a mechanical advantage that allows the firefighter to easily control the trigger and thus the fluid discharge from the nozzle.