JPH01344A - Exhaust gas recirculation system operation diagnostic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[Industrial Application Field 1] The present invention relates to an operation diagnostic device for an exhaust gas recirculation (EGR) device installed in a vehicle engine.
This invention relates to prevention of misdiagnosis in a diagnostic system using a temperature sensor such as a thermistor. [Conventional technology I The EGR8 device is installed as one of the exhaust gas purification methods for a vehicle engine, and reduces NOx by recirculating a portion of the exhaust gas to the intake system and lowering the combustion temperature. Therefore, if the EGR valve sticks or something else malfunctions, the EGR
Even if it does not work, there is a risk that the engine will continue to operate because it will not affect the engine output. Therefore, a temperature sensor is added to the EGR device to measure the gas temperature, and the operating state is diagnosed based on this temperature. Conventionally, regarding the operation diagnosis of the above-mentioned EGR device, there is a prior art disclosed in, for example, Japanese Utility Model Publication No. 52-31886. □Here, connect in series a switch that opens and closes based on the humidity sensor, a switch that opens and closes based on engine speed, and an alarm.
It has been shown that a warning is issued if the sensor temperature drops due to a failure of the EGR device when the engine is rotating at high speed. [Problem to be Solved by the Invention 1] By the way, in the prior art described above, since the i9 VfI ``J'' is detected immediately from the change in the electrical resistance value of the temperature sensor, there is a risk of misdiagnosis. , there is a response delay in the detection of temperature sensors such as thermistors, and it takes several seconds to accurately detect the temperature. It is an object of the present invention to provide an operation diagnostic device for an EGR device that accurately diagnoses the EGR device by taking into consideration the above-described problems. A predetermined delay time is set after the operating conditions for circulation are established, the maximum value detected by the temperature sensor during the delay time is stored, and the maximum temperature value is used to diagnose the failure. [Function] ] Based on the above configuration, the operating conditions for EGR are established and E
When entering the R state and importing the detected value of the temperature sensor,
A delay time corresponding to the pincer response y5 delay is set, and the gas humidity can be accurately detected and fault diagnosed at the maximum value within this time. Thus, in the present invention, it is possible to absorb the response delay in diagnosis using a temperature sensor and perform accurate diagnosis.

【Example】

Embodiments of the present invention will be described below based on the drawings. In FIG. 1, reference numeral 1 is an engine body, 2 is a throttle valve, 3 is an intake manifold, and 4 is an exhaust manifold. The exhaust gas recirculation passage 6 of the EGR device 5 communicates between the intake and exhaust manifolds 3 and 4, and the exhaust gas EG in the middle of reflux passage 6
R valve 7 is provided. In addition, the boat 8 near the throttle valve 2 is
It communicates with the operating side of the GR valve 7, and when the solenoid valve 21 is turned off at a predetermined throttle opening, exhaust gas is recirculated by listening to the EGR valve 7 due to boat negative pressure. Next, regarding the failure diagnosis control system, exhaust) 9
A temperature sensor υ10 is installed in the middle of the flow path θ. In addition, a throttle opening sensor 11, an engine speed sensor 1
2. Water temperature sensor 13, solenoid valve operation sensor 14
The signals from these sensors 11 to 14 are input to the EGR condition establishment determining section 1G of the control unit 15. E
The GR condition establishment determination unit 16 is a solenoid valve 217Jv.
When a predetermined period of time elapses in the EGR operation state in which the engine closes and the throttle opening, engine speed, and water temperature satisfy set values, it is determined that the condition is satisfied. The detection signal of the temperature sensor 10 is input to the temperature detection section 17, and after determining whether the condition is satisfied, the maximum humidity within the time set by the delay time setting section 18 is stored. This temperature value is input to a failure determination section 19, and if the temperature is below a set value, a failure is determined and the check lamp 20 is turned on. The operation of the operation diagnosis device having the above configuration can be explained using flowchart 1 in Fig. 2.
This will be explained using the time chart in Figure 2 and Figure 3. First, check the operating status of the solenoid valve, and execute it only if the EGR operation is active. When the water temperature Tw is warmed up with the set value 8 or higher, the throttle opening θ is within the range of the set value θ1°02, and the engine speed is NO is also the set value N1. When the pressure is within the range of N2, the boat negative pressure acts on the EGR valve 7 through the passage 9, and EGR is performed. Now start timer R1 (the above is indicated as (c) in Figure 2.3). When the predetermined time t1 has passed under this operating condition, it is assumed that the EGR is working sufficiently, and a flag is set when it is determined that the condition is met (same (6) is displayed). Thereafter, if the other timer R2 is checked and the number is not zero, the condition has already been met, so the timer counts and a delay time is provided. If timer R2 is 0, ask the flag set;
If it is not set, EGR is not being performed, so return to ■ (Start) to initialize everything. If set, timer Rt is counted and the process returns to (2). At this time, since the timer R2 is not zero, the timer R2 is further increased by a force C (the part indicated as approximately C). And timer R2
is the delay time [amount temperature Hinley 10 until it becomes 2 or more
The exhaust gas humidity is detected moment by moment, compared with the maximum value up to the previous time, the maximum value is updated, and the maximum value Tgm is stored. Fault diagnosis is performed using this maximum 1aTgm, and if it is equal to or greater than the set value b, it is determined to be normal, and if it is equal to or less than b, it is determined to be a failure. Incidentally, the present invention can also be applied to various diagnostics using temperature measured by a temperature sensor. [Effects of the Invention] As described above, according to the present invention, in a diagnostic system for an EGR device based on the temperature of a temperature sensor, sensor 1
Since the temperature is detected with a delay time corresponding to the response delay of the sensor, the accuracy of temperature detection is improved and misdiagnosis is prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the EGR device production/diagnosis device of the present invention, FIG. 2 is a flowchart of the operation, and FIG. 3 is a time chart 6 of temperature detection. 5... Exhaust gas recirculation device, 15... Failure diagnosis control unit! to, 1G... [EGR condition establishment determination unit, 17
...Temperature detection section, 18...Delay time setting section, 1
9...Failure determination section. Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Patent attorney: Makoto Kobashi Ukiyo Patent attorney: Susumu Murai Figure 2

Claims (1)

[Scope of Claims] An exhaust system that provides a predetermined delay time after the operating conditions for exhaust gas recirculation are established, stores the maximum value detected by a temperature sensor during the delay time, and diagnoses a failure using the maximum temperature value. Operation diagnostic device for gas recirculation equipment.