Temperature adjustment apparatus utilizing state detector detecting the electrical state of the Peltier device

Patent metadata

Field	Value
Publication number	US-9759458-B2
Application number	US-201414531057-A
Country	US
Kind code	B2
Filing date	Nov 3, 2014
Priority date	Nov 7, 2013
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A drive circuit of a temperature adjustment apparatus drives a Peltier element at a desired output amount. A state detector detects an electrical state of the Peltier element. A control circuit calculates a desired output amount based at least on the electrical state of the Peltier element, determines a control quantity for driving the Peltier element at the desired output amount, and controls the drive circuit at the control quantity.

First claim

What is claimed is:

1. A temperature adjustment apparatus for adjusting a temperature of a control object using a Peltier element, comprising:
a drive circuit configured to drive the Peltier element at a desired output amount;
a state detector configured to detect an electrical state of the Peltier element;
a control circuit configured to calculate the desired output amount based at least on the electrical state of the Peltier element, determine a control quantity for driving the Peltier element at the desired output amount, and control the drive circuit at the control quantity;
a parameter setter configured to set a parameter related to operation of the Peltier element;
a temperature sensor to that detects the temperature of the control object; and
a temperature regulator that outputs an operating quantity to the control circuit for adjusting the temperature of the control object to a desired temperature,
wherein:
the drive circuit comprises a DC power source that causes a direct current to flow to the Peltier element, by applying a DC voltage as the output amount to the Peltier element,
the DC power source is a variable power source in which a value of the direct current can be varied by changing a value of the DC voltage,
the control circuit performs a variable control by controlling the DC power source, whereby the value of the DC voltage and the value of the direct current are changed to desired values responsive to the control quantity,
the electrical state of the Peltier element is defined by the DC voltage, the direct current, and an electromotive force of the Peltier element,
the state detector includes a voltage detecting control circuit configured to detect the DC voltage, a current detecting circuit configured to detect the direct current, and an electromotive force detecting circuit configured to detect the electromotive force,
the parameter setter sets a temperature adjustment capability limiting value for limiting a temperature adjustment capability of the Peltier element with respect to the control object,
the control circuit controls the drive circuit based on the operating quantity, the parameter, the DC voltage detected by the voltage detecting circuit, the direct current detected by the current detecting circuit, and the electromotive force detected by the electromotive force detecting circuit, and
by controlling the DC power source based further on the temperature adjustment capability limiting value, the control circuit limits the DC voltage and the direct current.

2. The temperature adjustment apparatus according to claim 1 , wherein:
the parameters are a maximum voltage value, which is a maximum value of the DC voltage that can be applied to the Peltier element, a current limit value, which is a maximum value of the direct current flowing to the Peltier element, and a temperature difference limit value, which is a permissible value of a temperature difference between a heat-absorbing side and a heat-radiating side of the Peltier element corresponding to the electromotive force;
the control circuit further comprises a temperature difference converter, which converts the electromotive force detected by the electromotive force detecting circuit into the temperature difference; and
the drive circuit is controlled based on a comparison between the maximum voltage value and the DC voltage detected by the voltage detecting circuit, a comparison between the current limit value and the direct current detected by the current detecting circuit, and a comparison between the temperature difference limit value and the temperature difference converted by the temperature difference converter.

3. The temperature adjustment apparatus according to claim 2 , wherein in the control circuit:
in a case that a DC voltage is applied to the Peltier element from the DC power source, and when the direct current detected by the current detecting circuit exceeds the current limit value, control with respect to the DC power source is switched from a variable voltage control, which is configured to vary a value of the DC voltage, to a constant current operation for holding the value of the DC voltage at a predetermined value while maintaining the direct current at the current limit value; and
wherein, if the direct current detected by the current detecting circuit becomes less than or equal to the current limit value, the control with respect to the DC power source is restored from the constant current operation to the variable voltage control.

4. The temperature adjustment apparatus according to claim 2 , wherein, in a case that the temperature difference converted by the temperature difference converter has exceeded the temperature difference limit value, the control circuit controls the DC power source so that the temperature difference becomes less than or equal to the temperature difference limit value, and the value of the DC voltage is reduced.

5. The temperature adjustment apparatus according to claim 4 , wherein, when the DC power source is controlled so that the temperature difference becomes less than or equal to the temperature difference limit value, but the temperature difference continues to rise, the control circuit suspends application of the DC voltage to the Peltier element from the DC power source.

6. The temperature adjustment apparatus according to claim 2 , wherein:
the drive circuit further comprises a polarity reversing circuit that switches polarity of the DC voltage output from the DC power source, and applies the DC voltage the polarity of which has been switched to the Peltier element; and
when the polarity of the DC voltage that is applied to the Peltier element is switched by the polarity reversing circuit, the control circuit carries out a constant current control to maintain the direct current at a fixed value, and controls the DC power source so that a time constant of the direct current becomes longer.

7. The temperature adjustment apparatus according to claim 1 , wherein based on the temperature adjustment capability limiting value, the control circuit limits an output range of the DC voltage with respect to the operating quantity.

8. The temperature adjustment apparatus according to claim 1 , wherein the control circuit limits the DC voltage and the direct current until the temperature of the control object reaches a predetermined temperature corresponding to the temperature adjustment capability limiting value, wherein when the temperature of the control object reaches the predetermined temperature, limiting of the DC voltage and the direct current is released.

9. The temperature adjustment apparatus according to claim 1 , wherein the control circuit further comprises a failure detector, which judges that the Peltier element is suffering from a failure, in an event that the value of the direct current detected by the current detecting circuit deviates from characteristics of the DC voltage and the direct current based on a temperature difference between a heat-absorbing side and a heat-radiating side of the Peltier element corresponding to the electromotive force.

10. The temperature adjustment apparatus according to claim 1 , wherein:
the control circuit carries out detection of the electromotive force by the electromotive force detection circuit in a time band in which application of the DC voltage to the Peltier element from the DC power source is temporarily suspended, and upon completion of detection of the electromotive force, reapplies the DC voltage to the Peltier element from the DC power source; and
in a case that application of the DC voltage and detection of the electromagnetic force are performed alternately, a detection time of the electromotive force is s

Assignees

• Smc Corp

Inventors

• Nakajima Tadao

Classifications

• G01K3/14

  in respect of space · CPC title

• F25B2321/0212

  of electric power, current or voltage · CPC title

• F25B21/04 Primary

  reversible · CPC title

• G05D23/1919

  characterised by the type of controller · CPC title