JP2011191278A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor capable of diagnosing which pressure introducing piping or hose has been clogged. <P>SOLUTION: The information that a pressure introducing piping or hose on the upper stream side and the lower stream side of a diesel particulate filter (hereinafter, DPF) has been clogged is accurately acquired by diagnosis of abnormal conditions, and a failure of a pressure sensor device itself is detected. Thus, an erroneous pressure difference before and after DPF is not output. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a failure diagnosis of a DPF by a pressure sensor device and a pressure sensor device itself, which is installed in an exhaust gas purification device for an internal combustion engine having a DPF.

  In an internal combustion engine of a diesel engine, exhaust particulate matter (hereinafter referred to as PM) contained in exhaust gas discharged from the main body of the internal combustion engine is a problem. Has advanced to Europe.

  When the amount of clogging increases due to PM collection in the DPF, the differential pressure before and after the DPF changes compared to when there is little clogging, and this is used to set a threshold at which the differential pressure before and after the DPF can maintain the DPF capability. When it exceeds, it is determined that the DPF is clogged based on the output of the differential pressure.

  The DPF has a high temperature for burning the collected PM, and thus a device for detecting pressure cannot be directly installed in the vicinity of the DPF. Therefore, pressure is propagated to the pressure sensor device by providing a pipe or hose from the DPF as a conventional structure.

  Since carbon and moisture contained in the exhaust environment enter the piping and hose, clogging occurs in the pressure introduction piping and hose due to accumulation of carbon, etc., and freezing of moisture in a low temperature environment. There may be a problem that pressure does not propagate to the sensing element.

  Similarly, the same problem occurs when a failure occurs in the pressure detection element. In this case, there is a possibility that the differential pressure before and after the DPF cannot be output normally.

  However, it is possible to determine whether one of the pressure introduction pipes and the hose is clogged according to the output state of the differential pressure before and after the DPF based on the presence or absence of vibration generated in the differential pressure output of the pressure sensor device. However, it is impossible to detect which one of the pressure introduction pipe and the hose installed upstream and downstream of the DPF is clogged.

  In addition, when the pressure detection element itself that detects pressure fails, output similar to the above occurs, such as vibration in the differential pressure output, in addition to the fact that the normal DPF clogging amount cannot be output. Therefore, it cannot be surely diagnosed that the pressure introduction pipe and the hose are clogged.

JP 2009-53083 A

  An object of the present invention is to provide a pressure sensor capable of diagnosing which pressure introduction pipe and hose are clogged.

  In the pressure sensor apparatus which detects the pressure difference of the upstream and downstream of the diesel particulate filter (henceforth DPF) which collects the exhaust particulate installed in the exhaust system of a diesel engine via pressure introduction piping and a hose The output means for outputting the pressures upstream and downstream of the DPF as absolute pressures, clogging and breakage in the pressure introduction pipe and the hose, and abnormality and failure of the semiconductor pressure detecting element for detecting the pressure are diagnosed And a diagnostic means.

  According to the present invention, based on the output of the pressure sensor device, it is possible to diagnose the abnormality of the pressure introduction pipe and the hose installed upstream and downstream of the DPF and the DPF, and which is abnormal, and the difference due to the sensor failure. It is possible to prevent erroneous output of pressure and determination of clogging.

The diesel engine block diagram of the internal combustion engine which shows one Example of this invention. 1 shows an embodiment of the present invention. The example of an operation timing chart of FIG. 2 is shown. The example of an operation timing chart of FIG. 2 is shown. The example of an operation timing chart of FIG. 2 is shown.

  Examples will be described below.

  FIG. 1 shows the overall configuration of a diesel engine that is an internal combustion engine provided with the pressure sensor device of the present invention.

  A turbocharger 3 and a DPF 4 are provided in the exhaust passage 2 connected to the exhaust port of the internal combustion engine 1. The pressure sensor device 5 is interposed between the DPF downstream pressure introduction pipe 8 communicating with the exhaust passage 6 upstream of the DPF 4, and outputs a signal corresponding to the differential pressure before and after the DPF 4 and the absolute pressure before and after the DPF 4. Output to the ECU 9.

  An air flow sensor 11 is installed in the intake passage 10 to detect the amount of intake air. The intake passage 10 is provided with an intercooler 12 and an intake throttle valve 13 and communicates with the intake manifold 14.

  Further, an exhaust gas recirculation passage 15 communicates with the exhaust passage 2, and an EGR cooler 16 and an exhaust gas recirculation passage throttle valve 17 are provided.

  An output signal from the sensors (5, 11) and output signals from various sensors (not shown) are input to the ECU 9 to inform the state of each part.

  FIG. 2 shows the configuration of the pressure sensor device used in the present invention.

  The pressure sensor device 5 used for the diagnostic control of the DPF 4 in this embodiment is configured to calculate a differential pressure from the pressure detection element 18 upstream of the DPF 4 and the pressure detection element 19 downstream of the DPF 4 and the two detected pressure signals. The pressure calculation circuit 20, the pressure detection element 18, and the pressure detection element 19 are monitored, and a failure diagnosis circuit 21 is provided for diagnosing whether or not each is broken.

  FIG. 3 shows an operation timing chart when the pressure detection element 18 or 19 of FIG. 2 has failed and at KEY-ON.

  When there is no failure diagnosis circuit, even if the pressure detection element that detects the pressure upstream and downstream of the DPF fails, a differential pressure is output based on the output of the failed pressure detection element.

  In this case, for example, a value exceeding the threshold for determining DPF clogging is output, or the differential pressure output in the engine operating state thereafter is transmitted to the ECU, which is different from normal information. In addition, there is a possibility of performing control such as DPF regeneration processing.

  By having a failure diagnosis circuit for two pressure detection elements, for example, the output of the failure diagnosis circuit is transmitted to the differential pressure calculation circuit, and for example, the differential pressure output outside the specified differential pressure output range shown in FIG. 4 is forcibly controlled. Thus, the abnormality of the pressure sensor device can be accurately transmitted to the ECU, and erroneous control including erroneous DPF regeneration processing can be avoided.

  FIG. 5 shows an operation timing chart when the pressure introduction pipes upstream and downstream of the DPF are clogged.

  Normally, when the engine is in operation, vibration is generated in the output of the pressure detection element due to the influence of pressure introduction piping connected to the pressure detection element from upstream and downstream of the DPF, exhaust pulsation including exhaust gas passing through the DPF, and the like.

  If either one of the pressure introduction pipes is clogged with foreign matter or icing, the output of the pressure detection element on the clogged side will not be propagated from the pressure introduction pipe, so there will be no output vibration and the output will be fixed. . Since the differential pressure output is calculated based on the outputs of the two pressure detection elements, when the output of one of the pressure detection elements is fixed, vibration also occurs in the differential pressure output.

  It is possible to determine whether one of the pressure introduction pipes is clogged only by the differential pressure output by detecting the presence or absence of vibration with the ECU, but it is not possible to judge which one of the pressure introduction pipes is clogged. For this reason, it is necessary to investigate and replace those who are not clogged in the pressure introduction pipe.

  The same applies to the case where either one of the pressure detection elements is broken.

  When the fault diagnosis circuit can determine whether the pressure is due to clogging of the pressure introduction pipe or the pressure detection element, and the pressure detection element is normal. By providing means for sending the absolute pressure to the ECU, erroneous control can be avoided.

  In addition, since it has a function that can determine which pressure inlet pipe is clogged, if the pressure inlet pipe is clogged, it is possible to replace only the clogged pipe. Man-hours can be reduced.

  In particular, the present invention relates to a pressure sensor device that measures the pressure of exhaust gas of an internal combustion engine.

1 Internal combustion engine 2, 6 Exhaust passage 3 Turbocharger 4 DPF
5 Pressure sensor device 7 DPF upstream pressure introduction pipe 8 DPF downstream pressure introduction pipe 9 ECU
DESCRIPTION OF SYMBOLS 10 Intake passage 11 Air flow sensor 12 Intercooler 13 Intake throttle valve 14 Intake manifold 15 Exhaust recirculation passage 16 EGR cooler 17 Exhaust recirculation passage throttle valves 18 and 19 Pressure detection element 20 Differential pressure calculation circuit 21 Fault diagnosis circuit

Claims (7)

In a pressure sensor device that detects a pressure difference between upstream and downstream of a diesel particulate filter (hereinafter referred to as DPF) that collects exhaust particulates installed in an exhaust system of a diesel engine via a pressure introduction pipe and a hose.
Output means for outputting the upstream and downstream pressures of the DPF as absolute pressures;
Diagnosis means for diagnosing clogging, breakage in the pressure introduction pipe and the hose, and abnormality or failure of the semiconductor pressure detection element for detecting pressure,
A pressure sensor comprising: In claim 1,
A pressure sensor using an absolute pressure type semiconductor pressure detecting element as means for detecting respective pressures as a basis for deriving a pressure difference between upstream and downstream of the DPF. In claim 1,
A pressure sensor, which is made possible by monitoring the pressure upstream and downstream of the detected DPF as means for detecting clogging in the pressure introduction pipe and the hose. In claim 3,
When the pressure introduction pipe or hose is clogged, the pressure upstream and downstream of the DPF becomes a constant value, and there is a means to transmit it to the outside, and either the pressure introduction pipe or hose upstream or downstream of the DPF is clogged. A pressure sensor characterized by determining whether or not. In claim 1,
A pressure sensor comprising a failure diagnosis circuit for diagnosing the presence or absence of a failure of a semiconductor pressure detection element for detecting pressures upstream and downstream of a DPF. In claim 5,
A pressure sensor comprising means for transmitting a differential pressure output to an upper limit and a lower limit outside a specified output range and transmitting them to the outside when an abnormality of the semiconductor pressure detection element is detected. In claim 5,
A pressure sensor characterized by comparing outputs of semiconductor pressure detecting elements for detecting pressures upstream and downstream of a DPF as a method for determining a failure of the semiconductor pressure detecting element.

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