Pressure sensor diagnostic device

Abstract

To provide a pressure sensor diagnostic device capable of suppressing deterioration of diagnostic accuracy.SOLUTION: A pressure sensor diagnostic device executes an abnormality diagnosis of a pressure sensor connected to an exhaust pipe of an engine via a pressure introduction pipe. The pressure sensor diagnostic device includes: an ice-up determination section that determines whether the pressure introduction pipe is clogged due to ice-up; an ice melting determination section that determines whether the ice in the pressure introduction pipe has been molten when the ice-up determination section makes an affirmative determination; and a stop section that stops the abnormality diagnosis in the case where the ice-up determination section makes an affirmative determination and where the ice melting determination section makes a negative determination.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a pressure sensor diagnostic device. [Background technology]

[0002] A pressure sensor is connected to an engine exhaust pipe via a pressure introduction pipe, and there is a technique for eliminating blockage of this pressure introduction pipe due to icing (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-039013 A Summary of the Invention [Problem to be solved by the invention]

[0004] If an abnormality diagnosis of the pressure sensor is performed when the pressure introduction pipe is clogged due to freezing, there is a risk that the accuracy of the diagnosis will decrease.

[0005] Therefore, an object of the present invention is to provide a pressure sensor diagnostic device in which a decrease in diagnostic accuracy is suppressed. [Means for solving the problem]

[0006] The above object can be achieved by a pressure sensor diagnostic device that performs abnormality diagnosis on a pressure sensor connected to an engine exhaust pipe via a pressure introduction pipe, the pressure sensor diagnostic device comprising: a freezing determination unit that determines whether the pressure introduction pipe is blocked by freezing; a freezing / thawing determination unit that determines whether the ice in the pressure introduction pipe has melted when a positive determination is made by the freezing determination unit; and a stop unit that stops the abnormality diagnosis when a positive determination is made by the freezing determination unit and a negative determination is made by the freezing / thawing determination unit. Effect of the Invention

[0007] It is possible to provide a pressure sensor diagnostic device in which a decrease in diagnostic accuracy is suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Diagram 2] 4 is a flowchart illustrating control for determining whether or not to execute an abnormality diagnosis of a pressure sensor, which is executed by an ECU; [Diagram 3] 4 is a timing chart illustrating control for determining whether or not to execute an abnormality diagnosis of a pressure sensor, which is executed by an ECU; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Vehicle outline] FIG. 1 is a schematic diagram of a vehicle 1. The vehicle 1 is provided with an engine 10, drive wheels 15, and an ECU (Electric Control Unit) 50. The engine 10 is a power source for driving the vehicle 1. The vehicle 1 is an engine vehicle equipped with the engine 10, but is not limited thereto, and may be, for example, a hybrid vehicle equipped with a motor in addition to the engine 10. Rotational power of a crankshaft 12 of the engine 10 is transmitted to the drive wheels 15. The engine 10 is, for example, a gasoline engine having multiple cylinders, but may also be a diesel engine. An intake pipe 20 and an exhaust pipe 30 are connected to the engine 10. An intake air temperature sensor 21 and an air flow meter 22 are provided in the intake pipe 20. The intake air temperature sensor 21 detects the intake air temperature. The air flow meter 22 detects the intake air amount. The exhaust pipe 30 is provided with a catalyst 31 and a GPF (Gasoline Particulate Filter) 32 in this order from the upstream side. A pressure introduction pipe 33 is provided in the exhaust pipe 30 on the upstream side of the GPF 32. A pressure sensor 34 is provided at the tip of the pressure introduction pipe 33. The pressure sensor 34 detects the pressure inside the exhaust pipe 30 via the pressure introduction pipe 33.

[0010] The ECU 50 includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a storage device such as a flash memory, and performs various controls by executing programs stored in the ROM or the storage device. The ECU 50 controls the rotation speed and load of the engine 10 according to the amount of operation of the accelerator pedal operated by the driver. The intake temperature, intake air volume, and pressure detected by the intake air temperature sensor 21, the air flow meter 22, and the pressure sensor 34 are input to the ECU 50. The vehicle speed detected by the vehicle speed sensor 16 is also input to the ECU 50.

[0011] The ECU 50 executes an abnormality diagnosis of the pressure sensor 34 when a predetermined condition is satisfied. The abnormality diagnosis is a control for diagnosing the presence or absence of an abnormality in the pressure sensor 34, for example, by monitoring fluctuations in the detection value of the pressure sensor 34 within a certain period of time. This is an example of a pressure sensor diagnostic device that executes an abnormality diagnosis of the pressure sensor 34. As will be described in more detail later, the ECU 50 functionally realizes a freezing determination unit, a freezing / melting determination unit, and a stop unit using the above-mentioned CPU, RAM, ROM, storage device, etc.

[0012] Condensed water may freeze inside the pressure introduction pipe 33, causing ice formation and blocking the pressure introduction pipe 33. If the above-described abnormality diagnosis of the pressure sensor 34 is performed in such a state, the accuracy of the diagnosis may be reduced. Therefore, the ECU 50 executes execution / non-execution decision control for determining whether or not to perform the following abnormality diagnosis of the pressure sensor 34.

[0013] [Control for determining whether or not to perform abnormality diagnosis of pressure sensor 34] FIG. 2 is a flowchart illustrating an example of control for determining whether or not to perform an abnormality diagnosis of the pressure sensor 34, which is executed by the ECU 50. The ECU 50 determines whether or not the engine 10 is running (step S1). If the answer is No in step S1, this control ends. If the answer is Yes in step S1, the ECU 50 acquires the pulsation width of the detection value of the pressure sensor 34 (step S2). The pulsation width is the amplitude of the detection value of the pressure sensor 34. The pulsation of the detection value of the pressure sensor 34 is caused by the pulsation of the pressure in the exhaust pipe 30. The pulsation of the pressure in the exhaust pipe 30 is caused by exhaust gas being discharged from each cylinder of the engine 10 into the exhaust pipe 30 at different times. For example, if the engine 10 is a four-cylinder engine, pressure pulsation occurs four times every 180 degrees while the engine 10 rotates at a crank angle of 720 degrees. Therefore, for example, the ECU 50 may obtain the difference between the maximum and minimum values ​​of the detection value of the pressure sensor within 180 degrees of the crank angle as the pulsation width of the detection value of the pressure sensor .

[0014] Next, the ECU 50 judges whether the pulsation width is less than a predetermined value (step S3). Here, the predetermined value is set to the pulsation width when no blockage due to icing occurs in the pressure introduction pipe 33. Step S3 is an example of a process executed by the icing judgment unit. If the answer is No in step S3, it is assumed that no blockage due to icing occurs in the pressure introduction pipe 33, and the ECU 50 permits the execution of an abnormality diagnosis of the pressure sensor 34 (step S7).

[0015] If the answer is Yes in step S3, it is assumed that blockage due to icing has occurred in the pressure introducing pipe 33, and the ECU 50 stops the abnormality diagnosis of the pressure sensor 34 (step S4). Step S4 is an example of a process executed by the stopping unit.

[0016] Next, the ECU 50 calculates and accumulates a freeze-thaw index value (step S5), which will be described in detail later. The freeze-thaw index value is a value that indicates the degree of melting of the ice in the pressure introduction pipe 33. The ECU 50 determines whether the freeze-thaw index accumulated value is greater than a threshold value (step S6). The threshold value is set to a value that can be considered to indicate that the ice in the pressure introduction pipe 33 has melted. Step S6 is an example of a process executed by the freeze-thaw determination unit. If the answer is No in step S6, the ECU 50 executes the process of step S5 again. If the answer is Yes in step S6, the ECU 50 considers that the blockage due to ice in the pressure introduction pipe 33 has been resolved, and allows the execution of an abnormality diagnosis of the pressure sensor 34 (step S7).

[0017] The calculation of the freeze-thaw index value will be described. The ECU 50 acquires the intake air temperature, the intake air amount, and the vehicle speed from the intake air temperature sensor 21, the air flow meter 22, and the vehicle speed sensor 16, respectively. The ECU 50 calculates the freeze-thaw index value by referring to a map in which the freeze-thaw index value is defined according to the intake air temperature, the intake air amount, and the vehicle speed. The freeze-thaw index value corresponds to the amount of heat received by the pressure introduction pipe 33. In this map, the freeze-thaw index value is defined as a larger value as the intake air temperature is higher, the intake air amount is larger, and the vehicle speed is lower. This is because the higher the intake air temperature and the larger the intake air amount, the larger the amount of heat from the exhaust gas that the pressure introduction pipe 33 receives. Also, the lower the vehicle speed, the smaller the amount of heat that the exhaust gas is taken away by the running wind. Such a map is stored in the ROM in advance. The calculation of the freeze-thaw index value is not limited to such a map, and may be calculated by an arithmetic expression. In the above-mentioned step 5, the freeze-thaw index value calculated in this manner is integrated.

[0018] Fig. 3 is a timing chart illustrating control for determining whether or not to perform an abnormality diagnosis of the pressure sensor 34, which is executed by the ECU 50. Fig. 3 illustrates the transition of the vehicle speed, the intake air amount, a freeze-thaw index integrated value described later, the detection value of the pressure sensor 34, and the stop / permission of the abnormality diagnosis. Fig. 3 illustrates a case in which the pressure introduction pipe 33 is clogged with ice when driving starts, and the ice melts thereafter.

[0019] The vehicle 1 starts traveling, but the detection value of the pressure sensor 34 hardly changes due to blockage caused by icing in the pressure introduction pipe 33 (times t0 to t1, Yes in step S3). During this time, the integrated value of icing and melting increases gradually but remains below the threshold value (No in step S6). For this reason, the abnormality diagnosis of the pressure sensor 34 is stopped (step S4).

[0020] After that, the detection value of the pressure sensor 34 gradually increases and reaches a peak (time t1 to t2). This is thought to be because the air sealed in the space between the ice in the pressure introduction pipe 33 and the pressure sensor 34 expands due to the heat of the exhaust, etc., causing the pressure in this space to rise.

[0021] After that, the detection value of pressure sensor 34 gradually decreases while pulsating (time t2 to t3). This is thought to be because part of the ice in pressure introduction pipe 33 melts, causing a drop in the pressure in the space between the ice in pressure introduction pipe 33 and pressure sensor 34, pushing the ice out of pressure sensor 34. After that, when the freeze-thaw index integrated value becomes equal to or greater than the threshold value, execution of an abnormality diagnosis is permitted (Yes in step S6 after time t3).

[0022] As described above, while the pulsation width of the detection value of the pressure sensor 34 is less than the predetermined value and the pressure introduction pipe 33 is considered to be clogged with ice, and while the freeze-thaw index integrated value is less than the threshold value and the ice in the pressure introduction pipe 33 is considered not to have melted, the abnormality diagnosis of the pressure sensor 34 is stopped. This prevents a decrease in the diagnostic accuracy of the abnormality diagnosis of the pressure sensor 34.

[0023] In the above embodiment, the intake air temperature detected by the intake air temperature sensor 21 is used to calculate the freeze-thaw index value, but the outside air temperature detected by an outside air temperature sensor may be used, or the temperature of the cooling water of the engine 10 may be used. This is because the higher any of these temperatures is, the higher the exhaust temperature becomes, and the greater the amount of heat received by the pressure introduction pipe 33 becomes.

[0024] In the above embodiment, the base end of the pressure introduction pipe 33 is connected to the exhaust pipe 30 between the catalyst 31 and the GPF 32, but the connection position of the pressure introduction pipe 33 is not limited to this. For example, the pressure introduction pipe 33 may be connected to the exhaust pipe 30 downstream of the GPF 32, or may be connected to the exhaust pipe 30 both upstream and downstream of the GPF 32.

[0025] Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0026] 1 vehicle 10 Engine 30 Exhaust pipe 33 Pressure intake pipe 34 Pressure Sensor 50 ECU (pressure sensor diagnostic device, ice determination unit, ice melting determination unit, stop unit)

Claims

[Claim 1] A pressure sensor diagnostic device for diagnosing an abnormality of a pressure sensor connected to an exhaust pipe of an engine via a pressure introduction pipe, a freezing determination unit that determines whether the pressure introducing pipe is clogged due to freezing; a freeze / thaw determination unit that determines whether or not the freeze in the pressure introducing pipe has melted when a positive determination is made by the freeze determination unit; a stop unit that stops the abnormality diagnosis when the freezing determination unit makes a positive determination and the freezing / thawing determination unit makes a negative determination.

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