A Novel Methodology of Enhancing Vehicle Safety Using …
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of pressure at which the PRV should open. Initially, the blowdown pressure was too
low, which was then corrected by tweaking the design of the PRV.
We know that the force exerted by the spring is given by the formula,
F s = −kx
(1)
where ‘k’ is the spring stiffness and x is the displacement of the spring.
The required force necessary to overcome the force of the spring F s is F P , which
must be greater than F s.
However, the required force F t must be given only by the tire pressure. Since
pressure is given by the formula,
P = F P /A
(2)
where A is the area of the hole in the valve which is exposed to the tire pressure.
By tweaking the above parameters, the opening and closing of the valve can be
determined.
4 Setup, Testing, and Validation
4.1 Setup
• An additional valve hole was made in the wheel, and the PRV was fixed in the
wheel vertically opposite to the inflation valve.
• The wheel-tire assembly was caged inside an inflation chamber for safety.
• The wheel was inflated beyond the recommended inflation pressure to check the
opening and closing pressure of PRV.
4.2 Testing for Pressure Release Start/Release Stop
Ten valves were tested with a simple device attached to the valve filled with soap
solution. The opening and closing pressure was noted for five iterations for each
valve (Fig. 1).
During running conditions, the heat which builds up in the wheel causes the
pressure to increase. The recommended cold inflation pressure of the wheel is 130
psi, and the wheel has a marking which says, ‘140 PSI MAX (COLD).’ Hence, the
temperature rise during running conditions may bring the maximum allowance to
165 psi, so the PRV should be designed in such a way that even after the excessive
release of air, the pressure should not drop below 165 psi so that when the wheel
cools down, the pressure does not drop below 130–135 psi (recommended value).
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of pressure at which the PRV should open. Initially, the blowdown pressure was too
low, which was then corrected by tweaking the design of the PRV.
We know that the force exerted by the spring is given by the formula,
F s = −kx
(1)
where ‘k’ is the spring stiffness and x is the displacement of the spring.
The required force necessary to overcome the force of the spring F s is F P , which
must be greater than F s.
However, the required force F t must be given only by the tire pressure. Since
pressure is given by the formula,
P = F P /A
(2)
where A is the area of the hole in the valve which is exposed to the tire pressure.
By tweaking the above parameters, the opening and closing of the valve can be
determined.
4 Setup, Testing, and Validation
4.1 Setup
• An additional valve hole was made in the wheel, and the PRV was fixed in the
wheel vertically opposite to the inflation valve.
• The wheel-tire assembly was caged inside an inflation chamber for safety.
• The wheel was inflated beyond the recommended inflation pressure to check the
opening and closing pressure of PRV.
4.2 Testing for Pressure Release Start/Release Stop
Ten valves were tested with a simple device attached to the valve filled with soap
solution. The opening and closing pressure was noted for five iterations for each
valve (Fig. 1).
During running conditions, the heat which builds up in the wheel causes the
pressure to increase. The recommended cold inflation pressure of the wheel is 130
psi, and the wheel has a marking which says, ‘140 PSI MAX (COLD).’ Hence, the
temperature rise during running conditions may bring the maximum allowance to
165 psi, so the PRV should be designed in such a way that even after the excessive
release of air, the pressure should not drop below 165 psi so that when the wheel
cools down, the pressure does not drop below 130–135 psi (recommended value).