JP2007192045A - Abnormality detection device of temperature sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection device of a temperature sensor, which can certainly detect various kinds of abnormalities of the temperature sensor without false detection despite the environmental condition of an engine stop. <P>SOLUTION: The abnormality detection device of a temperature sensor is provided with a stop time determining means to determine whether or not the engine stop time reaches a predetermined time, a temperature difference determining means to determine whether or not the temperature difference between a detection temperature Tw of a water temperature sensor 32 and a detection temperature Ta of an air intake temperature sensor 31 is within the limit of the predetermined temperature difference when the engine stop time reaches the predetermined time, a detection temperature fluctuation range determining means to determine whether or not the fluctuation range of the water temperature detected during the specified temperature fluctuation range after the start of the engine is not less than a first predetermined value, or the fluctuation range of the air intake temperature detected during the specified temperature fluctuation range is not less than a second predetermined value, and an abnormality determining means to determine that there is an abnormality in either of the water temperature sensor 32 or the air intake temperature sensor 31 when the temperature difference is outside the predetermined scope, and the detection temperature fluctuation range determining result is less than the first or second predetermined value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature sensor abnormality detection device, and in particular, a temperature sensor abnormality that detects abnormality of a temperature sensor based on a change in detection information of the temperature sensor, for example, within a predetermined monitoring period after the engine is stopped for a certain period of time. The present invention relates to a detection device.

  In an engine of a vehicle such as an automobile, high driving performance is obtained by executing detailed electronic control based on sensor information from each part of the engine. It is necessary to detect at an early stage, and in particular, detection of an abnormality of the temperature sensor is important.

For this reason, in the conventional temperature sensor abnormality detection device, for example, when the engine stop time is measured based on time information from an in-vehicle device or the like and the engine stop time exceeds a predetermined time, a predetermined monitoring period after the engine is started A change in detection information (water temperature difference) of the water temperature sensor is monitored, and when the water temperature difference does not reach a certain temperature difference, the water temperature sensor is determined to be abnormal (for example, see Patent Document 1).
JP 2000-303898 A

  However, such a conventional temperature sensor abnormality detection device has a problem that the temperature sensor can only output on the high temperature side of the detection temperature range, that is, it can only detect abnormality when a so-called high temperature stack abnormality occurs. It was.

  Further, since it was determined that the cooling water temperature was uniformly lowered when the engine stop time exceeded a certain time, for example, a heating means such as a block heater was provided to improve startability in a low temperature environment. There has been a problem with high temperature soaks where the ambient temperature around the engine is very high, such as when it is provided or when the vehicle is left in the sun. That is, in such a case, even if the engine stop time is long, the detected temperature of the water temperature sensor remains high. Therefore, even if the water temperature difference within the predetermined monitoring period is monitored, the constant temperature difference that normally occurs (water temperature difference) It was easy to make a false detection that an abnormality occurred in the water temperature sensor.

  Accordingly, an object of the present invention is to provide an abnormality detection device for a temperature sensor that can reliably detect various abnormalities of the temperature sensor without erroneous detection, regardless of the environmental state when the engine is stopped. It is.

  In order to achieve the above object, the abnormality detection device for a temperature sensor according to the present invention provides (1) a stop time determination means for determining whether or not the engine stop time has reached a predetermined time, and a determination result of the stop time determination means. Based on the above, when the engine stop time has reached a predetermined time, the temperature between the detection temperature of the water temperature sensor that detects the cooling water temperature of the engine and the detection temperature of the intake air temperature sensor that detects the intake air temperature of the engine A temperature difference determining means for determining whether or not the difference is within a predetermined temperature difference; and a fluctuation range of the detected temperature of the water temperature sensor in a specific temperature fluctuation period after the engine is started is a first predetermined value. The detected temperature fluctuation range determining means for determining whether or not the fluctuation range of the detected temperature of the intake air temperature sensor during the specific temperature fluctuation period is equal to or greater than a second predetermined value and the determination result of the temperature difference determining means. And a temperature difference between a detected temperature of a water temperature sensor that detects a cooling water temperature of the engine and a detected temperature of an intake air temperature sensor that detects an intake air temperature of the engine based on a determination result of the detected temperature fluctuation range determining means. Of the water temperature sensor and the intake air temperature sensor when the detection result of the detected temperature fluctuation range determination means is less than the first predetermined value or less than the second predetermined value. And an abnormality determining means for determining that there is an abnormality in any of them.

  In this configuration, by setting the temperature equalization time of the engine necessary for the detected temperature difference between the water temperature sensor and the intake air temperature sensor to be within the range of the predetermined temperature difference after the engine is stopped as the predetermined time, When the determination result of the determination means falls within the predetermined temperature difference range, it can be determined that both the water temperature sensor and the intake air temperature sensor are normal, and conversely, the determination result of the temperature difference determination means is within the predetermined temperature difference range. When it becomes outside, it can be determined that either the water temperature sensor or the intake air temperature sensor is abnormal. Therefore, it is possible to detect various abnormalities of the temperature sensor without being limited to cases where a high temperature stack abnormality occurs. In addition, when the engine is started after the cooling water is partially heated by a block heater or the like while the engine is stopped or after a certain period of stoppage in a so-called high-temperature soak state, the water temperature is reduced during a specific temperature fluctuation period immediately after the start. Since the fluctuation range of the detected temperature of the sensor exceeds the first predetermined value or the fluctuation range of the detected temperature of the intake air temperature sensor exceeds the second predetermined value, the case of such an unusual start is identified. This makes it possible to prevent erroneous abnormality determination.

  In the temperature sensor abnormality detection device according to (1) above, (2) the fluctuation range of the detected temperature of the water temperature sensor is the difference between the water temperature detected during the specific temperature fluctuation period and the water temperature detected when the engine is started. Preferably, the fluctuation range of the detected temperature of the intake air temperature sensor is a difference between the intake air temperature detected during the specific temperature fluctuation period and the intake air temperature detected when the engine is started. With this configuration, when the engine is started after the cooling water is partially heated while the engine is stopped or after a certain period of stoppage in a so-called high-temperature soak state, the water temperature detected during a specific temperature fluctuation period immediately after the start Alternatively, since the difference between the intake air temperature and that at the time of engine start is clearly generated, it is possible to reliably identify such a case of start different from the normal case.

  In the temperature sensor abnormality detection device of (1) above, (3) when the determination result of the detected temperature fluctuation range determination means is not less than the first predetermined value or not less than the second predetermined value, the abnormality determination The means may stop determining whether there is an abnormality in either the water temperature sensor or the intake air temperature sensor. As a result, when the fluctuation range of the detected water temperature or the detected intake air temperature during a specific temperature fluctuation period exceeds the fluctuation range of the first or second predetermined value or more, the abnormality determination is stopped, and an erroneous abnormality is detected. The determination is surely prevented.

  In the temperature sensor abnormality detection device of (1) above, (4) when the determination result of the detected temperature fluctuation range determination means is not less than the first predetermined value or not less than the second predetermined value, the temperature difference The range of the predetermined temperature difference used for determination by the determination unit can be expanded. Thereby, when the detected water temperature or the detected intake air temperature in the specific temperature fluctuation period exceeds the first or second predetermined value, the range of the predetermined temperature difference used for determination by the temperature difference determination means is expanded. Thus, the normal determination is made up to the expanded temperature difference range, and erroneous abnormality determination is prevented.

  Further, in the temperature sensor abnormality detection device according to (1), (5) the detected temperature fluctuation range determining means is configured such that the detected temperature of the water temperature sensor during the specific temperature fluctuation period is a detected temperature at the start of the engine. It is preferable to determine whether or not the first predetermined value has been decreased. With this configuration, for example, by installing a block heater on the engine block, even when the cooling water is partially heated in the vicinity of the combustion chamber while the engine is stopped, the water temperature is changed during a specific temperature fluctuation period immediately after the engine is started. By capturing that the temperature detected by the sensor has once decreased, such a state can be identified, and erroneous abnormality determination can be reliably prevented.

  Alternatively, in (1) the temperature sensor abnormality detection device of the present invention described in (1), (6) the detected temperature fluctuation range determining means determines that the detected temperature of the intake air temperature sensor during the specific temperature fluctuation period is the start of the engine. It is preferable to determine whether or not the detected temperature has decreased by more than the second predetermined value. With this configuration, the engine is started after being stopped for a certain time in a so-called high-temperature soak state. In addition, when the detected temperature of the intake sensor once decreases immediately after the engine is started, this can be accurately grasped and erroneous abnormality determination can be reliably prevented.

  More preferably, in the temperature sensor abnormality detection device according to (1), (7) the detected temperature fluctuation range determining means determines that the detected temperature of the water temperature sensor during the specific temperature fluctuation period is equal to that at the start of the engine. It is determined whether or not the detected temperature has decreased by the first predetermined value or more, and the detected temperature of the intake air temperature sensor during the specific temperature fluctuation period is the first detected value with respect to the detected temperature at the start of the engine. It is determined whether or not it has decreased by a predetermined value of 2 or more.

  With this configuration, the temperature detected by the water temperature sensor and the intake air temperature sensor once decreases immediately after the engine is started, such as when the cooling water is heated while the engine is stopped, or when the engine is started after a certain period of stoppage in a so-called high-temperature soak state. When this is done, it is possible to accurately capture this and reliably prevent erroneous abnormality determination.

  According to the present invention, when the engine stop time reaches a predetermined time, the abnormality determination of the water temperature sensor and the intake air temperature sensor is performed based on whether or not the detected temperature difference between the water temperature sensor and the intake air temperature sensor is within a predetermined temperature difference range. By doing so, it is possible to detect various abnormalities of the temperature sensor without being limited to cases where a high temperature stack abnormality has occurred, and the state in which the cooling water is heated while the engine is stopped or the so-called high temperature soak When the detected temperature once decreases immediately after starting the engine, such as when the engine is started after stopping for a certain period of time in the state, the detected temperature fluctuation with a fluctuation range exceeding the first or second predetermined value in the specific temperature fluctuation period Is detected and the above-described case different from the normal case is identified, so that an erroneous abnormality determination can be prevented in advance. As a result, it is possible to provide a temperature sensor abnormality detection device that can reliably detect various abnormality of the temperature sensor.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
FIGS. 1-6 is a figure which shows the abnormality detection apparatus of the temperature sensor which concerns on the 1st Embodiment of this invention, The schematic structure is shown in FIG.

  First, the configuration will be described.

  An engine 1 shown in FIG. 1 is a multi-cylinder internal combustion engine mounted on an automobile, and a combustion chamber 13 partitioned by a piston 12 is formed in each cylinder 11 of the engine block 10. In the combustion chamber 13, an intake valve 16 and an exhaust valve 17 are driven to open at a predetermined timing by a valve mechanism (not shown) that responds to crank rotation (indicated by an arrow R in FIG. 1). A mixture of air and gasoline, which is fuel, is sucked through the intake port 14 and exhausted from the exhaust port 15 in the exhaust stroke following the compression stroke and expansion (explosion) stroke. A throttle valve 21 is provided in the intake pipe 20 that forms the intake port 14, a surge tank 22 is formed in the intake pipe 20 on the downstream side, and an injector 23 is further provided in the vicinity of the combustion chamber 13 on the downstream side. Has been placed. A spark plug 25 is disposed so as to be exposed in the combustion chamber 13. The injector 23 and the spark plug 25 are driven by a drive control unit 50, and the fuel injection timing and ignition timing are controlled.

  An intake air temperature sensor 31 that detects the temperature of intake air (hereinafter simply referred to as intake air temperature) is mounted on the upstream side of the throttle valve 21 in the intake pipe 20, and cooling water is supplied to the water jacket portion 11 a of the engine block 10. A water temperature sensor 32 for detecting the temperature (hereinafter simply referred to as water temperature) is mounted. Detection information of the intake air temperature sensor 31 and the water temperature sensor 32 is taken into an engine ECU (Electronic Control Unit) 40, respectively.

  The engine ECU 40 includes a CPU (Central Processing Unit) 41, a ROM (Read Only Memory) 42, a RAM (Random Access Memory) 43, a B-RAM (Back-up RAM) 44 as a backup memory using a battery, and an input interface. A circuit 46, an output interface circuit 47, and a communication interface circuit 48 are included. The input interface circuit 46 is connected to the intake air temperature sensor 31, the water temperature sensor 32, and the ignition switch 55, and the output interface circuit 47 is connected to the drive control unit 50. The communication interface circuit 48 is connected with, for example, a navigation device 60 (on-vehicle equipment) for car navigation, and fetches time information and timer commands (startup commands) from the navigation device 60 and preset control information. Can be output.

  The engine ECU 40 mainly transfers sensor information acquired from the input interface circuit 46, preset setting value information, and the like while exchanging data between the RAM 43 and the B-RAM 44 in accordance with a control program stored in the ROM 42. On the basis of this, predetermined arithmetic processing is executed, and a control signal is output from the output interface circuit 47 in accordance with the result, whereby engine electronic control processing is executed, and temperature sensor abnormality detection processing described later is executed. It is supposed to run.

  On the other hand, when the engine 1 is stopped, the engine ECU 40 is based on time information from the navigation device 60 (time information input from outside by radio communication) or time information of an internal clock circuit built in the engine ECU 40 itself. The date and time when the engine is stopped is confirmed and written in the B-RAM 44. When the engine 1 is subsequently started, the engine stop time is calculated and the engine 1 is calculated based on the calculation result. It functions as stop time determination means for determining whether or not the stop time has reached a predetermined time. The determination processing program as the stop time determination means is stored in the ROM 42 in advance. Further, the predetermined time is normally equal to the soaking temperature after the engine stop sufficient and sufficient for the temperature difference between the temperature detection portions of the water temperature sensor 32 and the intake air temperature sensor 31 to fall within the predetermined temperature difference after the engine 1 is stopped. For the engine 1 of the present embodiment, a time value of 4 hours or more, for example, 5 hours is set.

  Further, when the engine stop time is equal to or longer than the predetermined time, the engine ECU 40 detects the coolant temperature of the engine 1 and the engine 1 within a predetermined monitoring period from the start of the engine 1 this time. Based on the detected temperatures Tw and Ta with the intake air temperature sensor 31 that detects the intake air temperature, the abnormality of both the temperature sensors 31 and 32 is detected (details will be described later).

  Therefore, the engine ECU 40 has a temperature difference ΔT = Tws− between a detected temperature Tw (hereinafter referred to as Tws) of the water temperature sensor 32 when the engine is started and a detected temperature Ta (hereinafter referred to as Tas) of the intake air temperature sensor 31 when the engine is started. Tas is calculated by the CPU 41 and has a function of temperature difference determination means for determining whether or not the temperature difference ΔT is within a predetermined temperature difference range. A set value of a predetermined temperature difference range used as the temperature difference determination means is set in advance and is stored in, for example, the B-RAM 44 or the ROM 42. A determination processing program as the temperature difference determination means is stored in the ROM 42.

  The engine ECU 40 is also based on detection information from the water temperature sensor 32 and the intake air temperature sensor 31 as temperature detection means, for example, during a specific temperature fluctuation period after the engine 1 is started, for example, between 10 and 15 seconds from the start time. The fluctuation range of the detection temperature of the water temperature sensor 32 (current detection water temperature Tws−the detection water temperature Twmin at start-up) and the fluctuation range of the detection temperature of the intake air temperature sensor 31 during the specific temperature fluctuation period (current detection intake air temperature Tas− The detected intake air temperature Tamin at the time of starting is calculated, and at least one of these calculated fluctuation ranges, for example, whether the fluctuation range of the detected temperature Tw of the water temperature sensor 32 is equal to or greater than a first predetermined value DTW, The temperature sensor 31 has a function as a detected temperature fluctuation range determining unit that determines whether or not the fluctuation range of the detected temperature Ta is equal to or greater than a second predetermined value DTA. The first predetermined value DTW and the second predetermined value DTA used as the detected temperature fluctuation range determining means are set in advance as, for example, a predetermined reduced temperature and stored in the B-RAM 44 or stored in the ROM 42. Further, a determination processing program as the detected temperature fluctuation range determination means is stored in the ROM 42. In the present embodiment, the specific temperature fluctuation period starts when the engine 1 is started, and the fluctuation range of the detected temperature (the detected water temperature Tw and the detected intake air temperature Ta) in the specific temperature fluctuation period is the start of the engine 1. The specific temperature fluctuation period for monitoring the fluctuation range of the detected temperature does not include the starting point of the engine 1 and is a certain period immediately after that, which is calculated as the temperature drop of the detected water temperature Tws or the detected intake air temperature Tas. May be.

  Further, the engine ECU 40 determines that the temperature difference ΔT between the detected temperature of the water temperature sensor 32 and the detected temperature of the intake air temperature sensor 31 is based on the determination result as the temperature difference determination unit and the determination result as the detected temperature fluctuation range determination unit. It is outside the range of the predetermined temperature difference, and the determination result as the detected temperature fluctuation range determining means is less than the first predetermined value (the fluctuation range of the detected water temperature Tws−Twmin <the first predetermined value DTW) or the second Is less than the predetermined value DTA (detected intake air temperature fluctuation range Tas−Tamin <second predetermined value DTA), and it is determined that one or both of the water temperature sensor 32 and the intake air temperature sensor 31 are abnormal. It functions as a determination means. The determination processing program as the abnormality determination unit is stored in the ROM 42, and the determination result as the temperature difference determination unit and the determination result as the detected temperature fluctuation range determination unit are held by the RAM 43 until the abnormality determination process is completed. It has come to be.

  Note that the engine ECU 40 has a built-in soak timer that measures the stop time of the engine 1 even when the power is turned off, and can be turned on when the predetermined time elapses after the engine stops. Good. The ROM 42 may be a replaceable mounting form or a write-once type.

  The drive control unit 50 is provided with an energization control unit 52 for the injector 23 that operates in response to the injection control signal Sfi and the ignition timing control signal Sig from the output interface circuit 47, and a known igniter 51, and further, an ignition switch. A motor drive circuit for operating a starter motor (not shown) according to ON / OFF of 55 is provided.

  The navigation device 60 has a known configuration except that the navigation device 60 has an output port for providing time information and the like to the engine ECU 40.

  On the other hand, when the engine 1 is stopped, the block heater 70 may be attached as necessary. The block heater 70 is a heating means that can be attached to and detached from the engine block 10, and has a connection plug 71 that can be inserted into and removed from, for example, the outlet 101 connected to the commercial power source 102, thereby improving startability in a low-temperature atmosphere. Can do. That is, the block heater 70 warms the engine block 10 in the vicinity of the combustion chamber 13 or the cooling water in the engine block 10 while the engine 1 is stopped, so that combustion at the start of the engine is improved and startability is improved. It has become.

  In addition, since the process itself regarding the electronic control of a normal engine among the processes performed by engine ECU40 is the same as that of a well-known thing, description of the detailed structure for the control is omitted here.

  Next, the operation will be described.

  FIG. 2 is a schematic flowchart of the program showing the abnormality detection process of the temperature sensor executed by the engine ECU 40 in the present embodiment.

  First, when the ignition switch 55 is turned on (IG-ON in FIG. 2) or the soak timer for measuring the stop time from the stop point of the engine 1 is up (step S11), this is set as a start command. The process which demonstrates the function as a stop time determination means to start is started. Then, for example, the engine stop time is calculated based on the time information from the navigation device 60, or the stop time of the immediately preceding engine 1, that is, the soak time is a predetermined time or more with the time up of the soak timer as the engine stop time. It is checked whether or not it has been reached (step S12).

  At this time, if the soak time has not reached the predetermined time (in the case of no in step S12), the current process is terminated.

  On the other hand, if the soak time is equal to or longer than the predetermined time (Yes in step S12), a process that functions as a temperature difference determination unit is started, and the detected water temperature Tws and intake air temperature when the water temperature sensor 32 is started are started. After the temperature difference ΔT with the detected intake air temperature Tas at the start of the sensor 31 is calculated (step S13), whether or not the temperature difference ΔT is within a predetermined range (a predetermined temperature difference range) based on the calculated value. Determination is made (step S14).

  In this state, after the engine 1 is stopped, the temperature equalization time after the engine stop necessary for the temperature difference between the temperature detection portions of the water temperature sensor 32 and the intake air temperature sensor 31 to fall within a predetermined temperature difference has elapsed. Therefore, normally, the detected temperature difference ΔT between the sensors 31 and 32 is within a predetermined range, for example, two belt-like portions indicated by cross-hatching in FIG. 3B and a temperature range therebetween. It falls within a predetermined range, and the determination result of the temperature difference determination means is within a predetermined temperature difference range. Then, the engine ECU 40 determines that both the water temperature sensor 32 and the intake air temperature sensor 31 are normal by the function as the abnormality determination means (step S15).

  On the other hand, as shown in FIGS. 4 to 6, when the temperature difference ΔT is not within the predetermined temperature difference range (in the case of no in step S14), that is, the determination result of the temperature difference determination means is within the predetermined temperature difference range. When the temperature is outside, it is determined that there is a high possibility that either the water temperature sensor 32 or the intake air temperature sensor 31 is abnormal, and the following detection temperature fluctuation range (detection temperature decrease) is checked. To do.

  First, the detected temperature (water temperature) Tws of the water temperature sensor 32 at the time of starting and the detected temperature (intake air temperature) Tas of the intake air temperature sensor 31 at the time of starting are set to the current detected temperature (current water temperature, current intake air temperature), The initial values of the minimum values Twmin and Tamin of both detection temperatures are set to the current detection temperature that is the detection temperature at the start (step S16).

  Next, it is determined whether or not the engine has been started (step S17). If the engine 1 has not been started (in the case of no in step S17), the process proceeds to the step of setting the minimum value of the immediately preceding detected temperature (step S16). Return, the detection temperature Tws of the water temperature sensor 32 at the start and the detection temperature Tas of the intake air temperature sensor at the start are updated with the current detection temperature, and the initial values of the minimum values Twmin and Tamin of both detection temperatures are updated. The hour detection temperature is set (step S16). As a result, the starting water temperature and the starting intake air temperature are always updated to the detected temperatures immediately before starting.

  If the engine 1 has been started when determining whether or not the engine has been started, the determination result in this step is after the start (in the case of yes in step S17).

  At this time, next, the minimum value Twmin of the detected temperature of the water temperature sensor 32 and the minimum value Tamin of the detected temperature of the intake air temperature sensor 31 are the set value at the start and the current detected value (detected water temperature, detected intake air temperature). Is updated to the lower temperature value (step S18). Next, it is determined whether or not a specific temperature fluctuation period after the engine has started, for example, a period of 13 seconds has elapsed from the starting time, and the detected temperature of the water temperature sensor 32 is maintained until the specific temperature fluctuation period elapses. The minimum value Twmin and the minimum value Tamin of the detected temperature of the intake air temperature sensor 31 are updated to the lowest temperature value therebetween.

  Then, if a specific temperature fluctuation period after engine startup has elapsed (in the case of yes in step S19), then the temperature difference between the detected temperature Tws of the water temperature sensor 32 and the minimum value Twmin of the detected temperature of the water temperature sensor 32 at the time of startup. Tws-Twmin, that is, the fluctuation range of the water temperature Tw detected during a specific temperature fluctuation period is less than the first predetermined value DTW that is the maximum value of the normal water temperature fluctuation width during the same period (the temperature drop within the normal fluctuation range). ) Is determined (step S20).

  At this time, if the determination result is less than DTW (in the case of yes in step S20), then, the temperature difference Tas− between the detected temperature Tas of the intake air temperature sensor at the time of start and the minimum value Tamin of the detected temperature of the intake air temperature sensor 31. Tamin, that is, the fluctuation range of the intake air temperature Ta detected during a specific temperature fluctuation period is less than the second predetermined value DTA which is the maximum value of the normal intake air temperature fluctuation width during the same period (a decrease temperature within the normal fluctuation range). If the determination result is less than DTA (if yes in step S21), it is determined that one or both of the water temperature sensor 32 and the intake air temperature sensor 31 are abnormal, and the abnormality The presence determination result is written in a predetermined area of the RAM 43 (step S22).

  On the other hand, when it is determined that the maximum fluctuation range of the water temperature Tw detected during the specific temperature fluctuation period is equal to or greater than the first predetermined value DTW (in the case of no in step S20), or during the specific temperature fluctuation period When it is determined that the maximum fluctuation range of the detected intake air temperature Ta is equal to or greater than the second predetermined value DTA (in the case of no in step S21), each is determined as “no abnormality determination”, that is, the abnormality determination is stopped. Then, the current process ends.

  If the water temperature sensor 32 and the intake air temperature sensor 31 are normal, the detected temperatures of both the temperature sensors 31, 32 are usually almost as shown in the rightmost part of the graphs of FIG. 3 (a) and FIG. 6 (a). Since the temperature does not decrease, the temperature difference Tws−Twmin, which is a decrease in water temperature in a specific temperature fluctuation period, is less than the first predetermined value DTW, and the temperature difference Tas−Tamin, which is a decrease in intake air temperature in a specific temperature fluctuation period, It becomes less than the predetermined value DTA.

  Accordingly, only when the temperature difference ΔT is not within the predetermined temperature difference range (in the case of no in step S14) and when the water temperature sensor 32 and the intake air temperature sensor 31 are normal, the two temperature sensors 31, 32 are provided. It is determined that an abnormality has occurred.

  On the other hand, when the block heater 70 is attached to the engine 1 because the vehicle is used in a cold region and the atmosphere of the engine 1 becomes low temperature, a part of the engine 1 (near the combustion chamber) is heated by the block heater 70. As a result, even if a predetermined time elapses after the engine 1 is stopped, the detected temperature of the water temperature sensor 32 is maintained at a relatively high temperature, and the temperature difference that is the difference between the detected temperatures of the two temperature sensors 31 and 32 is maintained. ΔT may exceed the predetermined range as shown in FIG. 4B. Alternatively, in a high-temperature soak state in which the atmosphere in the vicinity of the engine 1 becomes high because the vehicle is left under the hot sun, as shown in FIG. Is maintained at a high temperature, and the temperature difference ΔT, which is the difference between the detected temperatures of the two temperature sensors 31, 32, may fall below a predetermined range as shown in FIG.

  In the present embodiment, whether or not this is the case is identified by the presence or absence of fluctuations exceeding a predetermined value of the detected water temperature Tw or the detected intake air temperature Ta immediately after the engine is started. That is, when the detected temperature once decreases immediately after starting, such as when the cooling water is heated while the engine is stopped or when the engine is started after stopping for a certain period of time in a so-called high-temperature soak state, FIG. Like the lowered water temperature dw and the lowered intake air temperature da shown in FIG. 5, the fluctuation range of the detected water temperature Tw or the detected intake air temperature Ta in the specific temperature fluctuation period exceeds the first predetermined value DTW or the second predetermined value DTA. Therefore, such a case can be identified. And abnormality determination is not performed in such an unusual state.

  As described above, in the temperature sensor abnormality detection device of the present embodiment, when the engine stop time reaches the predetermined time, the detected temperature difference ΔT between the water temperature sensor 32 and the intake air temperature sensor 31 is within the predetermined temperature difference. Depending on whether or not, the abnormality determination of the water temperature sensor 32 and the intake air temperature sensor 31 is performed. Abnormalities can be reliably detected.

  In addition, when the engine 1 is started after the cooling water is heated while the engine 1 is stopped or after a certain period of stoppage in a so-called high-temperature soak state, the first predetermined value DTW during the specific temperature fluctuation period. Alternatively, since the detected temperature fluctuation (for example, the temperature drop dw in FIG. 4 and the temperature drop da in FIG. 5) with a fluctuation range exceeding the second predetermined value DTA is detected and such a case is identified, erroneous abnormality determination Can be prevented. As a result, it is possible to provide a temperature sensor abnormality detection device that can reliably detect various abnormalities of the temperature sensors 31 and 32.

[Second Embodiment]
FIG. 7 is a schematic flowchart showing an abnormality detection processing program in the temperature sensor abnormality detection device according to the second embodiment of the present invention.

  In this embodiment, the device configuration itself is substantially the same as that of the first embodiment described above, and the fluctuation range of the detected water temperature or the detected intake air temperature during the specific detected temperature fluctuation period is the first or second predetermined value. The processing content in the case of exceeding is different from the above-described embodiment. Therefore, each component will be described using the same reference numerals as those in the first embodiment shown in FIG. 1, and the operation will be described as processing steps in the abnormality determination process in the first embodiment shown in FIG. The same steps are given the same step numbers, and the differences will be described in detail.

  In the present embodiment, when a specific temperature fluctuation period after engine startup has elapsed (in the case of yes in step S19), the detected temperature Tws of the water temperature sensor 32 at the time of startup and the water temperature sensor 32 of the water temperature sensor 32 are the same as in the above-described embodiment. A temperature difference Tws−Twmin with a minimum value Twmin of the detected temperature, that is, a first fluctuation range in which the maximum fluctuation range of the water temperature Tw detected during a specific temperature fluctuation period is the maximum value of the normal fluctuation range of the water temperature during the same period. It is determined whether or not the temperature is less than a predetermined value DTW (a decrease temperature within the normal fluctuation range) (step S20). At this time, if the determination result is less than DTW (if yes in step S20), then, the temperature difference Tas between the detected temperature Tas of the intake air temperature sensor 31 and the minimum value Tamin of the detected temperature of the intake air temperature sensor 31 at the time of starting. -Tamin, that is, the maximum fluctuation range of the intake air temperature Ta detected during a specific temperature fluctuation period is less than the second predetermined value DTA that is the maximum value of the normal intake air temperature fluctuation width during the same period (within the normal fluctuation range). It is determined whether or not the temperature falls. If the determination result is less than DTA (if yes in step S21), it is determined that one or both of the water temperature sensor 32 and the intake air temperature sensor 31 is abnormal, and the determination result indicating abnormality is stored in the RAM 43. It is written in a predetermined area (step S22).

  On the other hand, when it is determined that the maximum fluctuation range of the detected water temperature Tw in the specific temperature fluctuation period is equal to or greater than the first predetermined value DTW (in the case of no in step S20), or the detection absorption in the specific temperature fluctuation period. When it is determined that the maximum fluctuation range of the temperature Ta is equal to or greater than the second predetermined value DTA (in the case of no in step S21), that is, the determination result of the detected temperature fluctuation range determination means is equal to or greater than the first predetermined value DTW. Alternatively, when the value is equal to or greater than the second predetermined value DTA, a predetermined temperature difference range used for determination by the temperature difference determination means, that is, a detection temperature Tws of the water temperature sensor 32 at the time of engine start and detection of the intake air temperature sensor 31 at the time of engine start. A determination value that is a range in which the temperature difference ΔT with respect to the temperature Ta is determined to be normal (for example, two band-like portions indicated by cross-hatching in FIG. 4B and FIG. 5B) And a temperature range extending between them) is multiplied by a predetermined enlargement ratio (step S25). The expansion ratio here is a value exceeding 1, and is a value that expands to such an extent that the temperature difference ΔT at the time of use of the block heater 70 or the like or at the start in a high-temperature soak state is determined as the normal range. is there.

  In the present embodiment, the predetermined range (predetermined temperature difference range) is expanded by, for example, 20%, and the temperature difference ΔT is included in the expanded temperature difference range, and then the temperature difference is increased. If it is determined whether ΔT is within the predetermined range after enlargement (step S14), the determination result is yes and a normal determination is made (step S15).

  Also in this embodiment, the same effect as the above-described embodiment can be expected. Further, in the present embodiment, when the fluctuation range of the detected water temperature Tw in the specific temperature fluctuation period exceeds the first predetermined value DTW, or the fluctuation range of the detected intake air temperature Ta in the specific temperature fluctuation period is the second predetermined value. When the value DTA is exceeded, a predetermined temperature difference range used for determination by the temperature difference determination means, that is, the detected temperature Tws of the water temperature sensor 32 at the time of engine start and the detected temperature Tas of the intake air temperature sensor 31 at the time of engine start. Since the determination value, which is the range in which the temperature difference ΔT is determined to be normal, is expanded, normal determination is made up to the expanded temperature difference range, and erroneous determination of abnormality is prevented. In this case, since the determination processing result can be output, there is an advantage that the abnormality detection processing of the temperature sensor is not complicated.

  In each of the above-described embodiments, the fluctuation range of the detected temperature of the water temperature sensor (Tws−Twmin) during a specific temperature fluctuation period after engine startup and the fluctuation width of the detection temperature of the intake air temperature sensor during the specific temperature fluctuation period. (Tas−Tamin) is detected, and it is determined whether or not the corresponding predetermined value DTW or DTA or more. However, only the fluctuation range of the detection temperature of the water temperature sensor or the detection temperature of the intake air temperature sensor For example, it is possible to prevent erroneous detection by determining whether or not only the fluctuation range is equal to or greater than a predetermined normal fluctuation range for only one of which is highly likely to cause an abnormality. Further, in the above-described embodiment, the fluctuation range of the detected temperature in the specific temperature fluctuation period has been described on the basis of the detected water temperature Tws or the detected intake air temperature Tas at the time of starting the engine. However, the end of the specific temperature fluctuation period is described. The fluctuation range is calculated in such a manner that the detected water temperature Tw or the detected intake air temperature Ta at the time is set as the maximum value and the difference between the maximum value and the lowest detected water temperature Twmin or the detected intake air temperature Tamin in a specific temperature fluctuation period is taken. Is also possible.

It is the schematic block diagram which shows the abnormality detection apparatus of the temperature sensor which concerns on the 1st Embodiment of this invention. It is the schematic flowchart which shows the abnormality detection process of the abnormality detection apparatus of the temperature sensor which concerns on the 1st Embodiment of this invention. It is a graph which shows the detected temperature change immediately after the engine stop period in the case of absence of a block heater in the temperature sensor abnormality detection device according to the first embodiment of the present invention, and (a). The intake air temperature is shown, and (b) shows the change in the difference between the detected temperatures. It is a graph which shows the detected temperature change immediately after starting an engine stop period in the case of having a block heater in the temperature sensor abnormality detection device concerning a 1st embodiment of the present invention, and (a) is the detection water temperature and detection. The intake air temperature is shown, and (b) shows the change in the difference between the detected temperatures. FIG. 5 is a graph showing an engine stop period in a high-temperature soak state and a detected temperature change immediately after start in the temperature sensor abnormality detection device according to the first embodiment of the present invention. FIG. The temperature is shown respectively, and (b) shows the change in the difference between the detected temperatures. It is a graph which shows the detected temperature change immediately after starting an engine stop period in the case of water temperature sensor abnormality in the temperature sensor abnormality detection apparatus which concerns on the 1st Embodiment of this invention, and (a) is the detected water temperature and detection. The intake air temperature is shown, and (b) shows the change in the difference between the detected temperatures. It is the schematic flowchart which shows the abnormality detection process of the abnormality detection apparatus of the temperature sensor which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 10 Engine block 11 Cylinder 11a Water jacket part 14 Intake port 15 Exhaust port 16 Intake valve 17 Exhaust valve 20 Intake pipe 21 Throttle valve 23 Injector 25 Spark plug 31 Intake temperature sensor (temperature sensor)
32 Water temperature sensor (temperature sensor)
40 Engine ECU (stop time determination means, temperature difference determination means, detected temperature fluctuation range determination means, abnormality determination means)
41 CPU
42 ROM
43 RAM
44 B-RAM
46 Input interface circuit 47 Output interface circuit 48 Communication interface circuit 50 Drive control unit 60 Navigation device 70 Block heater (heating means)

Claims (7)

Stop time determining means for determining whether or not the engine stop time has reached a predetermined time;
Based on the determination result of the stop time determination means, when the engine stop time has reached a predetermined time, the detection temperature of the water temperature sensor that detects the cooling water temperature of the engine and the intake temperature that detects the intake air temperature of the engine. A temperature difference determination means for determining whether or not a temperature difference from a temperature detected by the temperature sensor is within a predetermined temperature difference range;
The fluctuation range of the detected temperature of the water temperature sensor in a specific temperature fluctuation period after the engine start is greater than or equal to a first predetermined value, or the fluctuation width of the detected temperature of the intake air temperature sensor in the specific temperature fluctuation period is the first. Detection temperature fluctuation range determining means for determining whether the value is equal to or greater than a predetermined value of 2,
Based on the determination result of the temperature difference determination means and the determination result of the detection temperature fluctuation range determination means, the temperature difference between the detection temperature of the water temperature sensor and the detection temperature of the intake air temperature sensor is outside the range of the predetermined temperature difference. And when the determination result of the detected temperature fluctuation range determination means is less than the first predetermined value or less than the second predetermined value, there is an abnormality in either the water temperature sensor or the intake air temperature sensor. An abnormality detection device for a temperature sensor, comprising: an abnormality determination means for determining.   The fluctuation range of the temperature detected by the water temperature sensor is a difference between the water temperature detected during the specific temperature fluctuation period and the water temperature detected when the engine is started, and the fluctuation range of the detection temperature of the intake air temperature sensor is the specific temperature. 2. The temperature sensor abnormality detection device according to claim 1, wherein a difference between an intake air temperature detected during a temperature fluctuation period of the engine and an intake air temperature detected when the engine is started.   When the determination result of the detected temperature fluctuation range determination means is not less than the first predetermined value or not less than the second predetermined value, the abnormality determination means is abnormal in either the water temperature sensor or the intake air temperature sensor. The temperature sensor abnormality detection device according to claim 1, wherein the determination as to whether or not there is is stopped.   Expanding the range of the predetermined temperature difference used for the determination by the temperature difference determination unit when the determination result of the detected temperature fluctuation range determination unit is not less than the first predetermined value or not less than the second predetermined value. The abnormality detection device for a temperature sensor according to claim 1.   The detected temperature fluctuation range determining means determines whether or not the detected temperature of the water temperature sensor in the specific temperature fluctuation period has decreased by more than the first predetermined value with respect to the detected temperature at the start of the engine. The abnormality detection device for a temperature sensor according to claim 1.   The detected temperature fluctuation range determination means determines whether or not the detected temperature of the intake air temperature sensor during the specific temperature fluctuation period has decreased by more than the second predetermined value with respect to the detected temperature at the time of starting the engine. The temperature sensor abnormality detection device according to claim 1.   The detected temperature fluctuation range determining means determines whether or not the detected temperature of the water temperature sensor during the specific temperature fluctuation period has decreased by more than the first predetermined value with respect to the detected temperature at the start of the engine. 2. It is determined whether or not the detected temperature of the intake air temperature sensor during the specific temperature fluctuation period has decreased by more than the second predetermined value with respect to the detected temperature at the start of the engine. An abnormality detection device for a temperature sensor according to 1.

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