JP2014062750A - Vehicle water temperature detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle water temperature detection device capable of detecting a highly accurate water temperature regardless of the temperature variation of a water temperature meter.SOLUTION: A vehicle water temperature detection device comprises: a water temperature meter 1 which is connected to a water temperature sensor B and displays a prescribed temperature range; control means 4 which has a resistor 2 in the wiring between the water temperature sensor B and a water temperature meter 1, inputs respective potentials of both ends of the resistor 2, detects a water temperature value beyond the prescribed temperature range; and switching means 3 which makes the resistor 2 short-circuited. The control means 4 activates the water temperature meter 1 keeping the resistor 2 in a short-circuit state by the switching means 3 after having detected the water temperature value.

Description

  The present invention relates to a vehicle water temperature detection device, and is particularly suitable for a vehicle water temperature detection device that detects a low water temperature separately from a normal water temperature display.

A conventional vehicle water temperature detection device is disclosed in Patent Document 1, for example. The vehicle water temperature detection device includes a water temperature sensor that outputs a change in engine coolant temperature as a resistance value change (analog signal), and a water temperature meter that displays the water temperature in response to the analog signal.
In addition, the apparatus includes a means for comparing and determining the water temperature based on the analog signal and an indicator for displaying the determination result of the comparison and determining means, and the low temperature outside the display range of the water thermometer is turned on by turning on a light emitting diode. Some display status with an indicator.

JP-A-8-326538

  However, the water thermometer described in Patent Document 1 is composed of a winding for moving the movement, and the resistance value of the winding is affected by the temperature change, and the temperature coefficient of the winding material (copper). Therefore, under an environment where the temperature change is large, there is a problem that a highly accurate analog signal cannot be input to the comparison / determination unit, and in particular, accurate temperature detection at a low water temperature cannot be performed.

  Therefore, the present invention aims at detecting a water temperature with high accuracy regardless of the temperature change of the water thermometer, paying attention to the above-mentioned problems.

  The vehicle water temperature detection device of the present invention is a vehicle water temperature detection device including a water temperature meter that is connected to a water temperature sensor and displays a predetermined temperature range, and is resistant to wiring between the water temperature sensor and the water temperature meter. And a control means for detecting a water temperature value outside the predetermined temperature range by inputting a potential between both ends of the resistor.

  In addition, it comprises switch means for enabling the resistor to be short-circuited, and the control means operates the water temperature meter in a state where the resistor is short-circuited by the switch means after completion of detection of the water temperature value. It is characterized by.

  Further, the control means performs a low temperature determination process for detecting whether or not the water temperature is low within a predetermined time after the vehicle is started.

  The present invention relates to a vehicle water temperature detection device, and can detect a water temperature with high accuracy regardless of a temperature change of a water thermometer.

The figure which shows the circuit structure in embodiment of this invention. The figure shown about the operation example based on the various signals of embodiment same as the above.

  Hereinafter, as an embodiment of the present invention, an example applied to a vehicle instrument will be described with reference to the drawings.

  The vehicle meter A notifies a vehicle user of measured values (vehicle state) detected by various sensors using an on-vehicle battery as a driving power source, and includes, for example, a fuel meter, a water temperature meter, and the like. In this case, the vehicle meter A is connected to a water temperature sensor B in order to operate the water temperature meter 1 as shown in FIG.

  The water temperature sensor B can be a thermistor whose resistance value varies depending on the temperature, and is connected to the water temperature gauge 1 via the resistor 2 and outputs an analog signal. In this case, the water temperature sensor B is for detecting the temperature of the cooling water of the vehicle engine, and has one end connected to the vehicle meter A and the other end grounded to the vehicle body.

  The vehicle meter A includes a water temperature gauge 1, a resistor 2, a switch means 3, a control means 4, and an indicator 5.

  The water thermometer 1 is configured such that a pointer rotates in accordance with an analog signal from the water temperature sensor B using a movement having a winding (copper wire) as a drive source, and an indicator portion including characters and scales to be indicated by the pointer This makes it possible to compare and interpret the water temperature that is the measured value. In this case, the water thermometer 1 is connected to an in-vehicle battery, and is driven by being directly supplied with a battery voltage (+ V) of about 12 V (hereinafter referred to as “direct motion”). The pointer is set so as to rotate along the indicator portion corresponding to a temperature of 50 degrees Celsius to 100 degrees Celsius.

  The resistor 2 is interposed in series in the wiring between the water temperature gauge 1 and the water temperature sensor B, and is wired so that the control means 4 can detect the potential between both ends.

  The switch means 3 can be a transistor such as an FET and is connected to the resistor 2 and the control means 4. When the control means 4 detects a low water temperature, the control means 4 energizes between the resistors 2. After the low water temperature detection processing, the control means 4 performs on control so as to short-circuit between the resistors 2.

  The control means 4 can be applied with an arithmetic means such as a microcomputer, based on a program stored in a storage unit such as a ROM, vehicle information input via an input / output interface, and an electric potential to be detected. A signal to the control unit (ECU) can be generated and emitted. For example, the control means 4 is also used as a control unit for displaying information such as a fuel gauge on a separate indicator.

  The control means 4 performs on / off control of the switch means 3 and samples the potential at both ends of the resistor 3 at the input during the period during which the switch means 3 is turned off, and compares the two sampled values with each other. To detect the water temperature. In this case, the control means 4 can detect each potential by inputting it to the analog / digital conversion port when inputting both-end potentials.

  Further, the control means 4 can determine activation according to a power input (not shown), and performs low temperature detection processing as an initial operation based on this activation. In this case, the activation determination is performed based on the battery voltage (+ V) input through the ignition switch, and the switch means 3 is energized for a predetermined time (for example, 1 second) T after the activation. Control off. Further, during the predetermined time T, the control means 4 samples each potential at both ends of the resistor 2 and performs a low temperature detection process based on this input.

  Further, the control means 4 performs on-control of the switch means 3 after a predetermined time T, and based on the analog signal from the water temperature sensor B until the resistor 2 is short-circuited and no battery voltage (+ V) is input. The linear motion control of the water temperature gauge 1 is performed.

  The control means 4 calculates the water temperature value of the water temperature sensor B based on the ratio of the two potential values as the low temperature detection process, and takes into account fluctuations in the voltage drop due to the temperature change of the water thermometer 1 and the like. A correct water temperature value can be detected. In this case, the control means 4 determines whether or not the water temperature value immediately after activation is equal to or less than a predetermined threshold value (for example, 10 degrees Celsius). It is assumed that the indicator 5 is activated and a signal for notifying the vehicle-side electronic control unit (ECU) of the low temperature state is output. Based on this signal, the electronic control unit can automatically perform the warm-up operation for a predetermined time (for example, 3 minutes). It is also possible to vary the warm-up operation time according to the temperature.

  The indicator 5 displays the vehicle state based on the control signal from the control signal 4, and in this case, a warning light (telltail) indicating that the cooling water is at a low temperature can be applied, and a light source such as a light emitting diode can be used. By illuminating, the design of the corresponding symbol mark is transmitted and notified. As the indicator 5, a glow indicator indicating a warm-up state can also be applied.

  Such a vehicle meter A is a vehicle water temperature detection device provided with a water temperature meter 1 that is connected to a water temperature sensor B and displays a predetermined temperature range. The body 2 is interposed, and a control means 4 is provided for detecting the water temperature value outside the predetermined temperature range by inputting each potential at both ends of the resistor 2.

  Therefore, a highly accurate water temperature can be detected regardless of the temperature change of the water thermometer. Moreover, since the control means 4 of the vehicle meter A can calculate the accurate water temperature even if the battery voltage fluctuates by calculating from the ratio of the potentials at both ends of the resistor 2, This is advantageous in a configuration in which the total 1 is operated.

  Moreover, the switch means 3 which enables the resistor 2 to be short-circuited is provided, and the control means 4 operates the water temperature meter 1 in a state where the resistor 2 is short-circuited by the switch means 3 after the detection of the water temperature value is completed. Thus, even with the configuration of the direct-acting water thermometer 1, the water temperature sensor B used in the water thermometer 1 can also be used to detect a low water temperature. Since it can be realized by performing time-dependent use of the predetermined time T after the start, the configuration such as wiring from the vehicle meter A to the water temperature sensor B can be simplified.

  Moreover, even if the control means 4 is the structure of the direct-acting water thermometer 1 by performing the low temperature determination process which detects whether water temperature is low temperature within the predetermined time T after starting of a vehicle, Automatic warm-up operation can be promoted. The control means 4 is provided with a signal communication circuit for converting into a predetermined communication protocol (multiplex communication signal) for exchanging various vehicle information with the electronic control unit outside the vehicle meter A, and this is used. This eliminates the need for a dedicated cable to notify the low temperature condition, and can be realized with a simple configuration.

  The vehicle water temperature detection device of the present invention has been described by way of example in the configuration of the embodiment described above, but the present invention is not limited to this, and the gist of the present invention is also in other configurations. It goes without saying that various improvements and display changes can be made without departing from the scope of the invention.

  The present invention can be applied to a vehicular water temperature detecting device, for example, an automotive vehicle, a motorcycle, or a vehicular composite meter including a water temperature meter mounted on a moving body including an agricultural machine or a construction machine.

DESCRIPTION OF SYMBOLS 1 Water temperature meter 2 Resistor 3 Switch means 4 Control means 5 Indicator A Instrument for vehicles (Water temperature detector for vehicles)
B Water temperature sensor

Claims (3)

A vehicle water temperature detection device including a water temperature meter connected to a water temperature sensor to display a predetermined temperature range,
A resistor is interposed in the wiring between the water temperature sensor and the water temperature meter, and control means is provided for inputting a potential at both ends of the resistor and detecting a water temperature value outside the predetermined temperature range. A water temperature detecting device for a vehicle.   The control unit includes a switch unit that enables the resistor to be short-circuited, and the control unit operates the water temperature meter with the switch unit short-circuited after the detection of the water temperature value. The vehicle water temperature detection device according to claim 1.   3. The vehicle water temperature detection device according to claim 1, wherein the control unit performs a low temperature determination process for detecting whether or not the water temperature is low within a predetermined time after the vehicle is started. .

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