Heater control for liquid flowing through a chamber
First Claim
1. Fluid flow apparatus comprisinga housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber,an electrically-powered heater located in said chamber,a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, anda controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off during duty cycle periods, the proportion of time said heater being on during a said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles,said controller determining said duty cycle by multiplying a heater constant times the difference between a commanded outlet temperature and said preheat temperature.
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Accused Products
Abstract
Fluid flow apparatus comprising a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of the chamber, an electrically-powered heater located in the chamber, a temperature sensor mounted to sense temperature of liquid prior to entering the chamber and providing inlet temperature signals indicating inlet temperature, and a controller electrically connected to receive the inlet temperature signals from the temperature sensor and to control a duty cycle of the heater in response to the inlet temperature signals.
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Citations
21 Claims
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1. Fluid flow apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, an electrically-powered heater located in said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off during duty cycle periods, the proportion of time said heater being on during a said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles, said controller determining said duty cycle by multiplying a heater constant times the difference between a commanded outlet temperature and said preheat temperature.
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8. Fluid flow apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, an electrically-powered heater located in said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off a plurality of times during each duty cycle period, the on and off conditions being distributed throughout said period, the proportion of time said heater being on during a said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles.
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10. Fluid flow apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, an electrically-powered heater located in said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off during duty cycle periods, the proportion of time said heater being on during said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles, a final temperature sensor downstream of a mixing chamber for mixing a second liquid with liquid from said outlet, said final temperature sensor providing final temperature signals, said controller receiving said final temperature signals and adjusting a commanded outlet temperature based on them.
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11. Dialysate preparation apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off during duty cycle periods, the proportion of time said heater being on during a said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles, a final temperature sensor downstream of a mixing chamber for mixing a second liquid with liquid from said output, said final temperature sensor providing final temperature signals, said controller receiving said final temperature signals and adjusting a command outlet temperature based on them.
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12. Dialysate preparation apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, an electrically-powered heater located in said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off during duty cycle periods, the proportion of time said heater being on during a said duty cycle being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles, said controller determining said duty cycle by multiplying a heater constant times the difference between a commanded outlet temperature and said preheat temperature.
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20. Dialysate preparation apparatus comprising
a housing defining a chamber and having an inlet and outlet for liquid flowing into and out of said chamber, an electrically-powered heater located in said chamber, a first temperature sensor mounted to sense temperature of liquid prior to being heated in said chamber, said first sensor providing preheat temperature signals indicating preheat temperature, and a controller electrically connected to receive said preheat temperature signals from said first temperature sensor and to control a duty cycle of said heater so as to be switched on and switched off a plurality of times during each duty cycle period, the on and off conditions being distributed throughout said period, the proportion of time said heater being on during a said duty cycle period being adjusted in response to said preheat signals, said heater being turned on or off for integer line cycles, said period including a plurality of line cycles.
Specification