Inflator with dynamic pressure compensation

Abstract

A method of inflating a vehicle tire, having an internal volume between about 10 gallons and about 12 gallons, includes discharging compressed air into the internal volume with an inflator. The inflator has an inflator housing, a motor within the inflator housing defining a motor axis and including an output shaft rotatable about the motor axis, a DC power source configured to provide power to the motor at a nominal output voltage, and a pump within the inflator housing and coupled to the output shaft. The pump includes a cylinder defining a cylinder axis and a piston that is reciprocable within the cylinder along the cylinder axis in response to rotation of the output shaft. By discharging compressed air into the internal volume, increasing a static pressure of the internal volume by 5 pounds per square inch (psi) from a starting pressure in the internal volume between 28 psi and 31 psi occurs within 40 to 60 seconds.

What is claimed is: 
     
         1 . A method of inflating a vehicle tire having an internal volume between about 10 gallons and about 12 gallons, the method comprising:
 discharging compressed air into the internal volume with an inflator, the inflator including
 an inflator housing, 
 a motor within the inflator housing, the motor defining a motor axis and including an output shaft rotatable about the motor axis, 
 a DC power source configured to provide power to the motor at a nominal output voltage, and 
 a pump within the inflator housing and coupled to the output shaft, the pump including a cylinder defining a cylinder axis and a piston that is reciprocable within the cylinder along the cylinder axis in response to rotation of the output shaft; and 
   by discharging compressed air into the internal volume, increasing a static pressure of the internal volume by 5 pounds per square inch (psi) from a starting pressure in the internal volume between 28 psi and 31 psi,   wherein increasing the pressure by 5 psi occurs within 40 to 60 seconds.   
     
     
         2 . The method of  claim 1 , wherein increasing the pressure by about 5 psi occurs within 50 to 60 seconds. 
     
     
         3 . The method of  claim 1 , wherein the nominal output voltage is 12V or less. 
     
     
         4 . The method of  claim 1 , wherein the DC power source is a battery pack removably coupleable to the inflator housing. 
     
     
         5 . The method of  claim 4 , wherein the inflator housing includes a recess in a front side of the inflator housing, and wherein the battery pack is at least partially disposed within the recess when the battery pack is coupled to the inflator housing. 
     
     
         6 . The method of  claim 1 , wherein the motor axis is transverse to the cylinder axis. 
     
     
         7 . The method of  claim 6 , further comprising a drive assembly configured to couple the motor to the pump, the drive assembly including a pinion fixed to the output shaft, a bevel gear meshed with the pinion, and a crank arm extending between the bevel gear and the piston, the crank arm configured to reciprocate the piston in response to rotation of the bevel gear. 
     
     
         8 . The method of  claim 7 , wherein the bevel gear is rotatable about a gear axis that is transverse to the motor axis and the cylinder axis. 
     
     
         9 . The method of  claim 1 , wherein the pump has a displacement per stroke between 6 cubic centimeters and 14 cubic centimeters. 
     
     
         10 . The method of  claim 1 , wherein the pump has a maximum flow rate between about 21,875 cubic centimeters per minute (cc/min) and about 63,000 cc/min. 
     
     
         11 . An inflator comprising:
 an inflator housing;   a motor within the inflator housing, the motor defining a motor axis and including an output shaft rotatable about the motor axis;   a DC power source configured to provide power to the motor at a nominal output voltage; and   a pump within the inflator housing and coupled to the output shaft, the pump including a cylinder defining a cylinder axis and a piston that is reciprocable within the cylinder along the cylinder axis in response to rotation of the output shaft;   wherein the inflator is operable to discharge compressed air into an internal volume between about 10 gallons and about 12 gallons to increase a static pressure of the internal volume by 5 pounds per square inch (psi) from a starting pressure in the internal volume between 28 psi and 31 psi, and   wherein increasing the pressure by 5 psi occurs within 40 to 60 seconds.   
     
     
         12 . The inflator of  claim 11 , wherein increasing the pressure by about 5 psi occurs within 50 to 60 seconds. 
     
     
         13 . The inflator of  claim 11 , wherein the nominal output voltage is 12V or less. 
     
     
         14 . The inflator of  claim 11 , wherein the DC power source is a battery pack removably coupleable to the inflator housing. 
     
     
         15 . The inflator of  claim 14 , wherein the inflator housing includes a recess in a front side of the inflator housing, and wherein the battery pack is at least partially disposed within the recess when the battery pack is coupled to the inflator housing. 
     
     
         16 . The inflator of  claim 11 , wherein the motor axis is transverse to the cylinder axis. 
     
     
         17 . The inflator of  claim 16 , further comprising a drive assembly configured to couple the motor to the pump, the drive assembly including a pinion fixed to the output shaft, a bevel gear meshed with the pinion, and a crank arm extending between the bevel gear and the piston, the crank arm configured to reciprocate the piston in response to rotation of the bevel gear. 
     
     
         18 . The inflator of  claim 17 , wherein the bevel gear is rotatable about a gear axis that is transverse to the motor axis and the cylinder axis. 
     
     
         19 . The inflator of  claim 11 , wherein the pump has a displacement per stroke between 6 cubic centimeters and 14 cubic centimeters. 
     
     
         20 . The inflator of  claim 11 , wherein the pump has a maximum flow rate between about 21,875 cubic centimeters per minute (cc/min) and about 63,000 cc/min.