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Abnormality determination apparatus and abnormality determination method for coolant temperature sensor, and engine cooling system

a technology of abnormality determination and abnormality determination, which is applied in the field of abnormality determination apparatus and abnormality determination method of coolant temperature sensor, and engine cooling system, which can solve problems such as coolant temperature sensor

Inactive Publication Date: 2013-08-22
TOYOTA JIDOSHA KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a coolant temperature sensor abnormality determination apparatus and method that can accurately determine if a coolant temperature sensor is abnormal without making false detections. The apparatus uses a control valve to increase the coolant temperature in a bypass passageway and detects the temperature change after the valve has opened. This allows for precise determination of abnormalities in the coolant temperature sensor, even if there is no heat source available. The method also reduces the time needed for determining the normality or abnormality of the sensor. Overall, the invention improves the accuracy and efficiency of coolant temperature sensor abnormality detection in cooling systems for engines.

Problems solved by technology

Incidentally, an example of the abnormality of the coolant temperature sensor is a stuck abnormality in which the sensor value is fixed to a certain value.

Method used

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  • Abnormality determination apparatus and abnormality determination method for coolant temperature sensor, and engine cooling system
  • Abnormality determination apparatus and abnormality determination method for coolant temperature sensor, and engine cooling system
  • Abnormality determination apparatus and abnormality determination method for coolant temperature sensor, and engine cooling system

Examples

Experimental program
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Effect test

example 1

of Determination Process

[0058]An example of the abnormality determination process for the heater inlet coolant temperature sensor 22 will be described with reference to a flowchart shown in FIG. 5. The process routine shown in FIG. 5 is executed by the ECU 300.

[0059]The process routine shown in FIG. 5 is started at the time point (IG-ON) when the ignition switch is turned on. When the process routine shown in FIG. 5 is started, the ECU 300, firstly in step ST101, picks the heater inlet coolant temperature thw2 occurring at the time of start of the engine from the output signal of the heater inlet coolant temperature sensor 22. Next, in step ST102, the ECU 300 reads in an abnormality determination value α (° C.) for use in the determination processes of step ST105 and step ST110 that are described later. This abnormality determination value a may be a constant value (e.g., α=5° C.), or may also be variably set according to the coolant temperature occurring at the time of start of the...

example 2

of Determination Process

[0079]Although in the example 1 of the determination process, it is determined that the changeover valve 10 has opened, at the time point when a certain time (time time 1) elapses following the start of electrification of the electric heater 15 of the changeover valve 10, it is also permissible to estimate the ambient coolant temperature Tvw of the temperature sensitive portion 14 of the changeover valve 10, and determine whether the changeover valve 10 has opened on the basis of the estimated value of the changeover valve's ambient coolant temperature Tvw.

[0080]Concretely, using the engine coolant temperature thw1 detected by the engine coolant temperature sensor 21, the ECU 300 estimates the changeover valve's ambient coolant temperature Tvw on the basis of a map or a calculation expression. At the time point when the estimated value of the changeover valve's ambient coolant temperature Tvw reaches the valve-opening temperature (70° C.) of the changeover va...

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Abstract

A coolant temperature sensor abnormality determination apparatus opens a changeover valve to increase the temperature of a coolant in a heater passageway if the amount of increase of the detected heater inlet coolant temperature value obtained when the intake air amount of an engine becomes equal to or greater than a predetermined value is small. Then, if the amount of increase in the detected heater inlet coolant temperature value after the changeover valve opens is greater than or equal to the predetermined value, the apparatus determines that the heater inlet coolant temperature sensor is normal. If the amount of increase in the detected heater inlet coolant temperature value is smaller than the predetermined value, the apparatus determines that the heater inlet coolant temperature sensor is abnormal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a cooling system of an engine (internal combustion engine) and, more particularly, to a coolant temperature sensor abnormality determination apparatus and a coolant temperature sensor abnormality determination method that determine the presence or absence of abnormality of a coolant temperature sensor of the cooling system.[0003]2. Description of Related Art[0004]With regard to an engine mounted in a vehicle or the like, a coolant jacket as a coolant passageway is provided in the engine (a cylinder block or a cylinder head), and the entire engine is cooled (or warmed) by circulating a coolant via the coolant jacket by a coolant pump. In conjunction with such a cooling system, there exists a technology in which a changeover valve that restricts the circulation of the coolant between an engine coolant passageway and a heater system (heater passageway) is provided, and while the engine is cold, the...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F01P11/18F01P7/16
CPCF01P7/165F01P7/16F01P2025/32F01P11/18
Inventor SAITOH, TATSUKI
Owner TOYOTA JIDOSHA KK
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