JPS6247528A - Correcting method for detected temperature of temperature sensor - Google Patents

Abstract

PURPOSE:To detect quantitatively a temperature with an equal accuracy to a temperature switch by providing one piece of temperature switch of a general structure so as to correct an output value of a temperature sensor. CONSTITUTION:A resistance value R(t) of a temperature sensor 1 is inputted as a signal value THW which has A/D-converted a voltage working on the sensor 1 through a pull-up resistance RP, and the resistance value R(t) in some temperature TS deg.C is detected. Also, a microcomputer 4 stores in advance a resistance value RC on a design of the sensor 1 in a switching temperature TC of a temperature switch 2 which has been determined in advance, in a ROM 8, and a CPU 7 calculates a correction factor K by a ratio of this resistance value RC, and the measured resistance value R(t) of the sensor 1 in the temperature TC. The microcomputer 4 executes a correcting calculation of the signal value THW in accordance with an expression I and an expression II by using the factor K, in the CPU 7. In this expression, RK(t) and THWK denote a resistance value which has been corrected in accordance with the factor K, and a signal value which has been corrected in accordance with the factor K, namely, an output value for showing a sensed temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for correcting the detected temperature of a temperature sensor such as a thermistor used for detecting the temperature of cooling water of an internal combustion engine.

Conventional Technology Temperature sensors such as thermistors that regularly detect the temperature of the cooling water of internal combustion engines or other temperatures are well known, and this type of temperature sensor continuously changes the output value according to the sensed temperature. do.

Problems to be Solved by the Invention In general, temperature sensors have a larger detection error than bimetallic or thermoferrite temperature switches, which can only detect changes in temperature exceeding a predetermined temperature. In practice, it is not possible to perform very precise temperature-responsive control using the temperature detected by the sensor.

On the other hand, a temperature switch has less detection error than a temperature sensor, so temperature response control using the temperature detected by this temperature switch is performed with relatively high precision. If this were to be carried out quantitatively, a large number of temperature switches with different switching temperatures would be required, which is completely impractical.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved method for correcting the temperature detected by a temperature sensor, which solves the above-mentioned problems.

Means for Solving the Problems According to the present invention, the above-mentioned object is to provide a method for correcting the temperature detected by a temperature sensor, in which switching is performed at a predetermined temperature when the same temperature as that applied to the temperature sensor is applied. Using a temperature switch, a correction value is calculated based on a numerical relationship between the output value of the temperature sensor when the temperature switch is switched and a predetermined design output value of the temperature sensor at the predetermined temperature. This is achieved by a method for correcting the temperature detected by a temperature sensor, which is characterized in that the output value of the temperature sensor is corrected using the correction value.

Functions and Effects of the Invention According to the temperature sensor detection temperature correction method according to the present invention,
By providing one temperature switch with a general structure, the output value of the temperature sensor is corrected, in other words, the detected temperature is corrected, and the temperature can be quantitatively measured with the same accuracy as a temperature switch using a general temperature sensor. The temperature detected by this temperature sensor can be used to perform precise quantitative temperature-related control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 shows one embodiment of a temperature detection device used to implement the method for correcting the temperature detected by a temperature sensor according to the present invention. In the figure, 1 indicates a temperature sensor, and the temperature sensor is a resistance type temperature sensor such as a thermistor.
As shown by the symbol in the graph of Figure 2, the resistance value decreases as the temperature rises, and the relationship between this resistance value and temperature is given by the following equation, as is well known. It will be done.

R(t): Resistance value Ro at absolute temperature TK
: Lower resistance value at T℃ S : Sensing temperature (℃) B : Thermistor constant (200o~50 In the figure, 2 indicates a temperature switch, and the humidity switch is a bimetal type or thermoferrite type. It is a temperature switch, and as shown by the symbol B in the graph of Fig. 2, it switches from the on state to the off state when the sensed temperature rises above a predetermined temperature TO. There is.

Both the temperature sensor 1 and the temperature switch 2 are mounted adjacent to each other, for example on the outer wall 3 of the internal combustion engine, such that each is subjected to substantially the same coolant temperature as the other.

The temperature sensor 1 is connected to the A/D converter 5 of the microcomputer 4, and the temperature switch 2 is connected to the input port of the microcomputer 4.

The microcomputer 4 includes a CPU 7, in addition to an A/D converter 5 and an input capotro. ! =ROM8. ! :RAM
9 and an output port 10, and takes in the resistance value R(t) of the temperature sensor 1 as a signal value THW obtained by A/D converting the voltage acting on the temperature sensor 1 via the pull-up resistor Rp, Resistance value R(t) at temperature TS℃
is detected according to equation (3).

The microcomputer 4 previously stores in the ROM 8 a design resistance value RC of the temperature sensor 1 at a predetermined switching temperature TO of the temperature switch 2, and the CPU 7 stores this resistance value RC and the switching humidity 7c. The correction coefficient K is determined by the ratio of the measured resistance value R([) of the temperature sensor 1 to (4).
It is calculated according to the formula.

However, THWC is the signal if at the predetermined temperature TC'C.
It is.

The microcomputer 4 uses the correction coefficient K in the CPU 7.
The correction calculation of the signal value THW is performed according to the following formula using . In the following equation, Rk(t) is the correction coefficient K
The resistance value corrected according to T I-I W k is a signal value corrected according to the correction coefficient K, that is, an output value indicating the sensed temperature.

Rk(t)-R(t)・K...<
5) Figure 3 shows a flowchart of temperature detection.

The routine of the flowchart shown in FIG. 3 is repeatedly executed at predetermined time intervals, and in step 1, it is determined whether or not the temperature switch 2 is in the on state, and if it is not in the on state, the process proceeds to step 2. move on. In step 2,
It is determined whether the temperature switch 2 was in the on state last time.

Last time, when the temperature switch 2 was in the on state, the process proceeds to step 3, and in step 3, the correction coefficient according to the above-mentioned equation (4) is sieved.

The flowchart in Fig. 4 shows the A/D conversion routine, and in this routine, correction calculation is performed according to equation (6) using correction coefficient K for signal field THW obtained by △/D conversion. It will be done.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an actual flow of a temperature detection device used to implement the method of correcting the detected temperature Iη of a temperature sensor according to the present invention, and FIG. 2 shows the operating characteristics of the temperature sensor and temperature switch. The graphs shown in FIGS. 3 and 4 are flowcharts showing the operation routine of the humidity sensor detected temperature correction method according to the present invention.

Claims (1)

[Claims] The temperature sensor detection temperature correction method uses a temperature switch that switches at a predetermined temperature when the same temperature as that applied to the temperature sensor is applied, and the output value of the temperature sensor when the temperature switch switches. and a predetermined design output value of the temperature sensor at the predetermined temperature. A method for correcting the detected temperature of a temperature sensor.