Thermocouple temperature detecting assembly

• US 4,135,402 A
• Filed: 08/10/1977
• Issued: 01/23/1979
• Est. Priority Date: 09/22/1976
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Nippon Soken, Inc.
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation), Nippon Soken, Inc.
• Inventors: Wakamatsu, Hisato, Yazawa, Akio
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/823,456
• Time in Patent Office: 531 Days
• Field of Search: 73/359 R, 73/341, 73/361
• US Class Current: 307/117
• CPC Class Codes: G01K 3/005 Circuits arrangements for indicating a predetermined temperature fire detection G08B17/00
• CPC Class Codes: G01K 7/026 Arrangements for signalling failure or disconnection of thermocouples
• CPC Class Codes: G01K 7/13 Circuits for cold-junction compensation

Abstract

A thermocouple temperature detecting assembly having a temperature detector provided with a thermocouple as a temperature detecting element is disclosed. In a lead wire which is connected to the temperature detector there is provided in the vicinity of the temperature detector a circuit such as a switching circuit for processing an electric signal in accordance with the ambient temperature. The temperature detector and the signal processing circuit are unseparably connected to each other and a compensating lead wire for compensating for the ambient temperature is used only for a short distance between the temperature detector and the signal processing circuit.

Claims

1. A thermocouple temperature detecting assembly comprising:

a thermocouple temperature detector for generating a detection voltage due to the thermoelectric effect of a thermocouple;

a first lead wire, securely connected to said thermocouple and adapted to match the thermoelectric effect of said thermocouple for transmitting said detection voltage;

a reference voltage generator, securely connected to said first lead wire, for generating a reference voltage which is varied in accordance with the ambient temperature thereof compensating the thermoelectric effect of said thermocouple;

an amplifier, securely connected to said first lead wire and packaged with said reference voltage generator, for amplifying said detection voltage transmitted through said first lead wire;

a second lead wire, securely connected to said amplifier, for transmitting the amplified voltage;

a detachable connector, connected to said second lead wire, for receiving said amplified voltage; and

a comparator, connected between said amplifier and said second lead wire and packaged with said reference voltage generator, for comparing said amplified voltage with said reference voltage;

whereby said amplifed voltage is reshaped into an on-off signal which is transmitted to said detachable connector through said second lead wire.

2. A thermocouple temperature detecting assembly according to claim 1 further comprising:

a breakage detection circuit, connected between said first lead wire and said amplifier, for detecting the breakage of said thermocouple and said first lead wire, said breakage detection circuit causing said amplifier to generate said amplified voltage which exceeds said reference voltage.

3. A thermocouple temperature detecting assembly according to claim 1 further comprising:

a voltage regulating circuit packaged with said reference voltage generator and having a zener diode which supplies said reference voltage generator with a constant voltage.

4. A thermocouple temperature detecting assembly according to claim 3, wherein said reference voltage generator includes:

a diode responsive to the changes of temperature thereof; and

a resistor connected in series with said diode for generating said reference voltage which is varied by said diode.

5. A thermocouple temperature detecting assembly comprising:

thermocouple means for generating a detection voltage due to the thermoelectric effect thereof;

first lead wire means electrically connected to said thermocouple means for transmitting said detection voltage;

amplifier means electrically connected to said first lead wire means for amplifying said detection voltage transmitted through first lead wire means;

casing means encasing said thermocouple means, said first lead wire means and said amplifier means therein; and

second lead wire means extending from said casing means for transmitting an electric signal corresponding to the amplified detection voltage from inside to outside said casing.

6. A thermocouple temperature detecting assembly according to claim 5 further comprising:

reference means encased within said casing means and electrically connected to said first lead wire means for establishing a reference voltage, said reference means including a diode effective to vary said reference voltage in response to the temperature of said first lead wire means; and

comparator means encased within said casing means and electrically connected to said amplifier means and said reference means for comparing said amplified detection voltage with said reference voltage, said comparator means being effective to vary the signal level of said electric signal transmitted through said second lead wire means.

7. A thermocouple temperature detecting assembly according to claim 6, wherein said second lead wire means comprises a pair of electric lead wires across which a direct current voltage is supplied, and wherein said reference means further comprises resistors connected in series with said diode across said electric lead wires for dividing said direct current voltage to establish said reference voltage.