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WO1997000432A1 - Ensemble mesureur de temperature - Google Patents

Ensemble mesureur de temperature Download PDF

Info

Publication number
WO1997000432A1
WO1997000432A1 PCT/GB1996/001077 GB9601077W WO9700432A1 WO 1997000432 A1 WO1997000432 A1 WO 1997000432A1 GB 9601077 W GB9601077 W GB 9601077W WO 9700432 A1 WO9700432 A1 WO 9700432A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
voltage signal
circuit
control unit
conditioning circuit
Prior art date
Application number
PCT/GB1996/001077
Other languages
English (en)
Inventor
Debra Ann Bezzina
Marsha Wenbel
Eric Blaine Ferch
Roberto Anthony Rossi
Robert Joseph Bolduc
Original Assignee
Ford Motor Company
Ford Motor Company Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Motor Company, Ford Motor Company Limited filed Critical Ford Motor Company
Publication of WO1997000432A1 publication Critical patent/WO1997000432A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • G01K7/22—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor
    • G01K7/24—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit
    • G01K7/25—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements the element being a non-linear resistance, e.g. thermistor in a specially-adapted circuit, e.g. bridge circuit for modifying the output characteristic, e.g. linearising

Definitions

  • the present invention relates generally to electronic controls for internal combustion engines and, more particularly, to temperature measuring systems for components of the internal combustion engine.
  • the present invention is a temperature measuring assembly for measuring temperature.
  • the temperature measuring assembly uses a voltage source supplying a constant voltage signal.
  • the temperature measuring assembly includes a thermistor and an input port operatively connected to the thermistor.
  • An input conditioning circuit is electrically connected to the voltage source and the input port .
  • the input conditioning circuit has a predetermined impedance.
  • the input conditioning circuit and said thermistor sensor define a voltage divider to variably divide the constant voltage signal to create a variable voltage signal.
  • An analog to digital converter is electrically connected to the input conditioning circuit and converts the variable voltage signal to a digital signal .
  • a control unit is electrically connected to the analog to digital converter and includes first and second transforms to transform the digital signal into a temperature signal.
  • a resistive circuit is operatively connected between said control unit and said input conditioning circuit and is switchable between open and close conditions such that the resistive circuit changes the variable voltage signal received by the analog to digital converter.
  • One advantage associated with the present invention includes providing a temperature measuring assembly to measure a temperature with improved accuracy over an extended range of temperatures without the addition of extra sensors and, thus, without the addition of additional costs.
  • the present invention has the ability to apply the temperature sensing assembly to any thermistor measurement system, e.g., transmission fluid temperature, intake air temperature, and the like.
  • FIG. 1 is a schematic of a temperature measuring assembly according to the present invention
  • FIG. 2 is a flowchart of a method of temperature measuring assembly according to the present invention.
  • FIG. 3 is a graphic representation of sensor voltage as a function of temperature.
  • a temperature measuring assembly is generally indicated at 10.
  • the temperature measuring assembly 10 is used to measure the temperature of a cylinder head of a internal combustion engine (neither shown) using a cylinder head temperature (CHT) sensor 12.
  • CHT cylinder head temperature
  • the CHT sensor 12 is a thermistor, it may be appreciated that the temperature measuring assembly 10 may be used to measure the temperature of any solid, fluid, or gas in or out of the motor vehicle environment.
  • An input port 14 operatively connects the CHT sensor 12 to an input conditioning circuit 16 which is, in turn, connected to a voltage source, five volts in one embodiment as shown in FIG. 1. It may be appreciated that the voltage source may vary its output and may even be a low frequency source.
  • the input conditioning circuit 16 and the CHT sensor 12 create a voltage divider for the voltage source which is variably dependent on the resistive value of the CHT sensor 12. The variability of the voltage divider is not dependent upon the input conditioning circuit 16 because it defines a predetermined constant impedance.
  • the input conditioning circuit 16 and the CHT sensor 12 create a variable voltage signal from the voltage signal .
  • the variable voltage signal is suitable for reception by an analog to digital (A/D) converter 18, discussed subsequently.
  • the predetermined constant impedance is suitably matched with the A/D converter 18.
  • the A/D converter 18 is a ratiometric converter and is electrically connected to the input conditioning circuit 16.
  • the A/D converter 18 uses the voltage source as a reference and converts the variable voltage signal into a digital signal. More specifically, the A/D converter 18 converts the analog signal received from the voltage divider created by the input conditioning circuit 16 and the CHT sensor 12, having units of volts, into a digital signal.
  • the digital signal is received by a control unit 20 which is electrically connected to the A/D converter 18.
  • the control unit 20 includes first and second transforms to transform the digital signal into a temperature signal . Referring to Table 1 and Table 2, the control unit 20 converts the number of pulses or counts received from the A/D converter 18 into a corresponding temperature reading based on the experimental temperature values. The determination as to which transform is to be used will be discussed subsequently.
  • the control unit 20 is a microprocessor. Cold End Transfer Function
  • a resistive circuit 22 is. operatively connected between the control unit 20 and the input conditioning circuit 16.
  • the resistive circuit 22 is switchable between open and close conditions such that the resistive circuit 22 changes the effective impedance of the CHT sensor 12, the input conditioning circuit 16 and the resistive circuit 22 which results in a change of the variable voltage signal received by the A/D converter 18. More specifically, the resistive circuit 22 is switchable between open and close conditions to change the voltage division created by the voltage divider, i.e., the CHT sensor 12, the input conditioning circuit 16, and the resistive circuit 22 when in the close condition, which, in turn, changes the effective impedance at the A/D converter 18. The effective impedance change at the A/D converter 18 results in the change of the variable voltage signal received thereby.
  • the resistive circuit 22 includes a MOSFET transistor 24 which is connected to a first resistor 26.
  • a switching circuit 28 is electrically connected between the control unit 20 and the resistive circuit 22.
  • the switching circuit 28 is controlled by the control unit 20 and switches the MOSFET transistor 24 when the temperature sensed by the CHT sensor 12 has increased or decreased beyond predetermined limits.
  • the predetermined limits are set by the control algorithm, discussed subsequently.
  • a graphic representation of these transforms is shown in FIG. 3. More specifically, when the CHT sensor 12 senses a temperature at approximately 200°F, the control unit 20 switches the MOSFET transistor 24 to close the resistive circuit 22 and, at the same time, operates using the second transform. Therefore, when using the second transform, a reading of approximately 4.200 V corresponds to a temperature reading of 200°F.
  • the second transform is used until approximately 160°F at which time the control unit 20 opens the MOSFET transistor 24 and returns to using the first transform.
  • Changing both the impedance at the A/D converter 18 and the transform used by the control unit 20 effectively doubles the range of sensing capabilities while still using one CHT sensor 12.
  • the hysteresis loop created by the two limits (200°F and 160°F) reduces excessive switching between the two impedance levels and the two transforms by requiring the temperature to change over 40°F before a switch occurs.
  • the CHT sensor 12 senses the temperature of a cylinder head to be 50°F at startup.
  • the sensor emits an input voltage signal of approximately 3.250V. In FIG. 3, this point is labelled at 30 along line 32.
  • the CHT sensor 12 produces an input voltage signal of decreasing voltage.
  • the second transform and resistive circuit 22 are switched into operation and the 4.300V signal, represented at 34 represents 200°F as opposed to 40°F at 36, which would be the indication had the control unit 20 been using the first transform (Table 1) and the resistive circuit 22 had been open.
  • the CHT sensor 12 continues along the path of line 38 and does not continue along line 40, as it would had the resistive circuit 22 not be closed.
  • the CHT sensor 12 Upon cooling of the cylinder head, the CHT sensor 12 reads signals along lines 38 and 42 until approximately 160°F where the resistive circuit 22 is open and the first transform is used to determine the temperature of the cylinder head.
  • the control unit 20 determines the temperature of the cylinder head to be the temperature corresponding to the input voltage signal received by the CHT sensor 12 according to line 32.
  • the input conditioning circuit 16 includes a second resistor 44 which is connected between the constant voltage source, a 5V power supply, and the first resistor 26.
  • the two resistors 26, 44 are also connected to a third resistor 46 and a capacitor 48.
  • the three resistors 26, 44, 46, and the capacitor 48 are all connected to the input port 14.
  • the capacitor 48 and a second capacitor 50 are connected to ground.
  • the second capacitor 50 and the third resistor 46 are connected to the input of the A/D converter 18.
  • the A/D converter 18 is connected to the control unit 20 which is connected to the switching circuit 28. More particularly, the control unit 20 is connected to a fourth resistor 52.
  • the fourth resistor 52 is also connected a fifth resistor 54 and the base of a transistor 56.
  • the emitter of the transistor 56 and the fifth resistor 54 are connected to ground.
  • a sixth resistor 58 and a seventh resistor 60 are connected to each other and the collector of the transistor 56.
  • the resistor 58 is also connected to a power supply Vp.
  • the seventh resistor 60 is connected to the gate of the MOSFET transistor 24.
  • the drain of the MOSFET transistor 24 is connected to the constant voltage source.
  • the source of the MOSFET transistor 24 is connected to the first resistor 26.
  • a determination 27 is made as to whether the two resistors 26,44 in parallel are being used. if both resistors 26,44 are being used, i.e., if the MOSFET transistor 24 is closed, the second transfer function is used 29. If, however, the MOSFET transistor 24 is open, the first transfer function is used 31. If the measured temperature is greater than a predetermined value 33, 200°F in one embodiment, the second transfer function is used 35 as well as the use of the two resistors 26,44 in parallel given the MOSFET transistor 24 provides minimal resistance. The resistor 26 is used when the MOSFET transistor 24 is closed.
  • the MOSFET transistor 24 is opened whereafter the second resistor 44 is used 39. If the measured temperature has not cooled to a temperature below the return value, the MOSFET transistor 24 remains closed and the impedance at the A/D converter 18 is maintained at a level using the two resistors 26,44 in parallel.
  • the accuracy 41 of the system which includes the temperature measuring assembly 10 and the CHT sensor 12, is approximately ⁇ 10°F between -40°F and 335°F and approximately 15°F between 335°F and 450°F.
  • the accuracy of a temperature measuring assembly 10 is far superior to that found conventionally.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

Cet ensemble, destiné à mesurer de façon précise une température à l'aide d'une source de tension fournissant un signal à tension constante, comprend une thermistance (12), un port (14) d'entrée servant à recevoir une entrée reliée de manière opérationnelle à la thermistance (12), un circuit (16) de conditionnement d'entrée, relié électriquement à la source de tension, ce circuit (16) et la thermistance (12) déterminant un diviseur de tension destiné à diviser de manière variable le signal à tension constante afin de créer un signal à tension variable, un convertisseur (18) analogique/numérique relié électriquement au circuit (16) de conditionnement et qui convertit le signal à tension variable en signal numérique, une unité (20) de commande reliée électriquement audit convertisseur (18) et comprenant des première et seconde transformées aux fins de transformer le signal numérique en signal de température, ainsi qu'un circuit (22) résistif relié de manière opérationnelle entre l'unité (20) de commande et le circuit (16) de conditionnement et pouvant être commuté entre un état ouvert et un état fermé, de manière à changer le signal à tension variable reçu par le convertisseur A/N (18).
PCT/GB1996/001077 1995-05-05 1996-05-07 Ensemble mesureur de temperature WO1997000432A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43604795A 1995-05-05 1995-05-05
US436,047 1995-05-05

Publications (1)

Publication Number Publication Date
WO1997000432A1 true WO1997000432A1 (fr) 1997-01-03

Family

ID=23730882

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1996/001077 WO1997000432A1 (fr) 1995-05-05 1996-05-07 Ensemble mesureur de temperature

Country Status (1)

Country Link
WO (1) WO1997000432A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998039624A1 (fr) * 1997-03-07 1998-09-11 Ericsson Inc. Diviseur de tension produisant une resolution commutable
FR2890168A1 (fr) * 2005-08-31 2007-03-02 Ngk Spark Plug Co Dispositif de commande de capteur de temperature.
EP2843384A1 (fr) * 2013-09-02 2015-03-04 LSIS Co., Ltd. Appareil de mesure de température utilisant une thermistance à coefficient de température négatif
EP2899548A1 (fr) * 2014-01-27 2015-07-29 Siemens Schweiz AG Circuit de détection polyvalent

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0108325A1 (fr) * 1982-10-29 1984-05-16 Zeltron Istituto Zanussi Per L'elettronica S.P.A. Dispositif de mesure de la température
JPH01188016A (ja) * 1988-01-22 1989-07-27 Hitachi Ltd ヒステリシスコンパレータ回路
WO1991008441A1 (fr) * 1989-12-06 1991-06-13 Robert Bosch Gmbh Dispositif pour ameliorer la precision d'une saisie de valeurs de mesure
JPH04277491A (ja) * 1991-03-05 1992-10-02 Matsushita Electric Ind Co Ltd 誘導加熱調理器の温度制御装置
EP0637733A1 (fr) * 1993-08-02 1995-02-08 Siemens Automotive S.A. Dispositif de mesure de la température

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0108325A1 (fr) * 1982-10-29 1984-05-16 Zeltron Istituto Zanussi Per L'elettronica S.P.A. Dispositif de mesure de la température
JPH01188016A (ja) * 1988-01-22 1989-07-27 Hitachi Ltd ヒステリシスコンパレータ回路
WO1991008441A1 (fr) * 1989-12-06 1991-06-13 Robert Bosch Gmbh Dispositif pour ameliorer la precision d'une saisie de valeurs de mesure
JPH04277491A (ja) * 1991-03-05 1992-10-02 Matsushita Electric Ind Co Ltd 誘導加熱調理器の温度制御装置
EP0637733A1 (fr) * 1993-08-02 1995-02-08 Siemens Automotive S.A. Dispositif de mesure de la température

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998039624A1 (fr) * 1997-03-07 1998-09-11 Ericsson Inc. Diviseur de tension produisant une resolution commutable
FR2890168A1 (fr) * 2005-08-31 2007-03-02 Ngk Spark Plug Co Dispositif de commande de capteur de temperature.
EP2843384A1 (fr) * 2013-09-02 2015-03-04 LSIS Co., Ltd. Appareil de mesure de température utilisant une thermistance à coefficient de température négatif
CN104422543A (zh) * 2013-09-02 2015-03-18 Ls产电株式会社 使用负温度系数热敏电阻器的温度测量装置
EP2899548A1 (fr) * 2014-01-27 2015-07-29 Siemens Schweiz AG Circuit de détection polyvalent
CN104808541A (zh) * 2014-01-27 2015-07-29 西门子瑞士有限公司 通用检测电路
US9148163B2 (en) 2014-01-27 2015-09-29 Siemens Schweiz Ag Versatile detection circuit

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