Constant temperature controller

Abstract

A constant temperature controller inexpensive and easy to operate, yet capable of accurately controlling the temperature with significantly reduced heat energy consumption, is provided. An operation mode of a cooler is switched between an idling mode and a loaded mode, based on a difference in temperature between a first temperature sensor and a third temperature sensor. For switching the operation mode, cooling power of the cooler is adjusted by changing a frequency of an inverter driving a compressor. Under the loaded mode, the cooling power of the cooler is adjusted by an aperture of an electronic expansion valve such that a difference between a temperature of a second sensor and a target temperature of a heater becomes a constant value.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a constant temperature controller for maintaining the temperature of an external heat load apparatus constant, and more particularly to a constant temperature controller that circulates a heat medium fluid of a constant temperature so as to maintain the temperature of the external heat load apparatus constant, employed for a chiller incorporated in a semiconductor manufacturing apparatus, or the like. DESCRIPTION OF THE RELATED ART [0002] A conventional constant temperature controller, generally called a chiller, is designed to circulate a heat medium fluid through a pipeline arranged in a loop through a cooler, a heater and an external heat load apparatus, so as to once supercool the liquid medium heated by the external heater with the cooler, and to heat the supercooled liquid medium with the heater thus to supply the external heat load apparatus with the liquid medium of a predetermined temperature specified by the ex...

AI Technical Summary

Benefits of technology

[0016] To avoid this, the present invention switches the operation mode based on the difference between the circulating fluid temperature at the inlet port of the cooler and the circulating fluid temperature at the outlet port of the heater. Such method enables quickly detecting the fluctuation in the difference in temperature even during the transition of the target temperature of the constant temperature controller, to thereby quickly react the fluctuation of the lead load, thus allowing switching the operation mode under a stabilized situation without overshooting or undershooting the target temperature by far. As a result, the operation mode can be timely switched and therefore the operation status can be quickly stabilized.

[0039] The constant temperature controller according to the present invention employs the heater with the PID feedback control function, which allows employing a small-sized electric heater thus to perform the energy-saving operation, as well as accurately controlling the temperature of the circulating fluid supplied to the external heat load apparatus.

Problems solved by technology

It is impossible to precisely foresee when the heat load that has been changed returns from the external heat load apparatus, i.e. the object of the temperature control.

Although the target temperature of the constant temperature controller is changed, the heat load that has been changed may not always return from the external heat load apparatus after the temperature of the heat medium fluid at the outlet port of the constant temperature controller has reached the newly set target and has been stabilized.

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