Patent ID: 7553143

Claim:
A method of manufacturing a rotor to be used in a dual-rotor lobe pump system for pumping a material at a desired periodic rate, the method comprising: selecting a desired periodic flow rate for said material; selecting a number of lobes for the rotor; selecting one of a thickness of the rotor or a spacing between the axis of rotation of the rotor and the axis of rotation of an adjacent rotor in said lobe pump; and determining a profile for the rotor based on the desired periodic flow rate, the number of lobes, and the one of the thickness or the spacing, such that when the rotor is operated within said dual-rotor lobe pump system, said material can be pumped at substantially the desired periodic flow rate, wherein the selecting the desired periodic flow rate comprises selecting a flow rate function F(t) in terms of time t, and wherein the determining comprises: determining a maximum flow rate F max , a minimum flow rate F min , and a period T from the desired periodic flow rate; designing the other of the thickness w or the spacing l of the rotor to satisfy the following formula: wl 2 = NTF min 2 π ⁡ ( F max - F min ) , where N is the number of lobes on the rotor; designing a profile, g x and g y , of a first half of one lobe of the rotor to satisfy the following formulas: g x = l 2 ⁢ cos ⁢ ⁢ π · t TN + l F min ⁢ ( F max - F min ) ⁢ ( F max - F ⁡ ( t ) ) ⁢ cos ⁡ ( π · t TN + sin - 1 ⁡ ( - TNF ′ ⁡ ( t ) ⁢ F max - F min π · F min ⁢ F max - F ⁡ ( t ) ) + π ) g y = l 2 ⁢ sin ⁢ π · t TN + l F min ⁢ ( F max - F min ) ⁢ ( F max - F ⁡ ( t ) ) ⁢ sin ⁡ ( π · t TN + sin - 1 ⁡ ( - TNF ′ ⁡ ( t ) ⁢ F max - F min π · F min ⁢ F max - F ⁡ ( t ) ) + π ) for ⁢ ⁢ 0 ≤ t ≤ T 2 , where ⁢ ⁢ F ′ ⁡ ( t ) = ⅆ F ⁡ ( t ) ⅆ t ; and g x = l 2 ⁢ cos ⁢ ⁢ π · t TN + l F min ⁢ ( F max - F min ) ⁢ ( F max - F ⁡ ( t ) ) ⁢ cos ⁡ ( π · t TN - sin - 1 ⁡ ( - TNF ′ ⁡ ( t ) ⁢ F max - F min π · F min ⁢ F max - F ⁡ ( t ) ) ) g y = l 2 ⁢ sin ⁢ π · t TN + l F min ⁢ ( F max - F min ) ⁢ ( F max - F ⁡ ( t ) ) ⁢ sin ⁡ ( π · t TN - sin - 1 ⁡ ( - TNF ′ ⁡ ( t ) ⁢ F max - F min π · F min ⁢ F max - F ⁡ ( t ) ) ) or ⁢ ⁢ T 2 ≤ t ≤ T ; ⁢ designing a profile of the second half of the one lobe of the rotor, such that said one lobe is symmetrical; and designing a profile of any remaining lobe or lobes of the rotor such that the remaining lobe or lobes have the same profile as said one lobe and all of the lobes are evenly spaced from each other.