JPS60187770A - Detection of disconnection of glow plug for internal- combustion engine - Google Patents

Abstract

PURPOSE:To permit to repair quickly and properly by permitting to detect easily and correctly the disconnection of the glow plug under a condition that it is arranged on the engine. CONSTITUTION:In case the operating signal of the glow plug 56 is not zero or upon starting or first idling of the engine, the cooling water temperature THW of the engine is confirmed whether it is higher than a predetermined value or not. Next, the revolving speed of the engine is confirmed whether it is higher than a predetermined value or 400rpm, for example, or not. These are confirmed so as to avoid a mis-decision in the initial period of starting of the engine wherein the ignition of fuel is not effected sufficiently. In case the revolving speed is higher than a set value, a difference between the maximum and minimum values of respective cylinders of the engine or the fluctuations Ni of the revolutions in respective cylinders are operated. If the value DELTANi is higher than the set value or the increase of revolution in each cylinder due to explosion is sufficient, it means that the glow plug 56 is being operated normally. In case the glow plug 56 of number (i) cylinder is disconnected, the value of DELTANi is smaller than the set value and, therefore, an alarm light 57 is put ON.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for detecting disconnection of a glow plug in an internal combustion engine, and is particularly suitable for use in electronically controlled diesel engines for automobiles, in which a glow plug is activated at least during startup or fast idling to ensure smooth ignition of fuel. The present invention relates to a method for detecting burnout of a glow plug in an internal combustion engine.

[Prior art]

Generally, in internal combustion engines, such as diesel engines, in which a glow plug is activated during startup or fast idling to ensure smooth fuel ignition, if the glow plug is disconnected due to engine vibration or changes over time, the engine will not start. Occurrence of malfunctions such as defects. Therefore, it is very important to quickly and reliably detect burnout of a glow plug, but in the past, it was not possible to detect burnout of a glow plug while it was still attached to the engine. , it is not possible to identify a starting failure due to glow plug disconnection, and it is not possible to quickly take an appropriate response to the starting failure, and other parts such as fuel injection pump, electronic control unit, glow plug relay, etc. The problem is that the glow plug has to be replaced first, and it takes a lot of time and man-hours to detect a break in the glow plug. Also, even if it can be assumed that the cause of the starting failure is a broken glow plug, it takes a long time to find the broken glow plug.
It is necessary to measure the resistance of each glow plug installed in each cylinder, which requires a great deal of effort and time.

OBJECT OF THE INVENTION 1 The present invention has been made to solve the above-mentioned conventional problems, and it is possible to easily and reliably detect disconnection of a glow plug while it is still attached to the engine.
Accordingly, it is an object of the present invention to provide a method for detecting disconnection of a glow plug in an internal combustion engine, which enables quick and accurate repair. [Structure of the Invention] The present invention provides a glow plug disconnection detection method for an internal combustion engine that operates the glow plug at least during startup or fast idling to ensure smooth ignition of fuel. As shown in FIG. The above object is achieved by including the step of determining that the glow plug of the relevant cylinder is disconnected when the speed or rotational fluctuation is smaller than a set value. Further, in an embodiment of the present invention, the disconnection determination is not performed when the engine cooling water temperature is extremely low, thereby preventing an erroneous determination at extremely low temperatures when the fuel becomes waxy and normal injection or ignition cannot be expected. It is designed to prevent this. Further, in another embodiment of the present invention, the disconnection determination is not performed at the initial stage of startup when the engine speed is very low, thereby preventing an erroneous determination at the early stage of startup when the fuel is not sufficiently ignited. It is designed to prevent this. (Action 1 of the invention) In the present invention, the engine rotational speed or rotational fluctuation for each cylinder when the glow plug is in a state where it should be operated,
When the engine rotational speed or rotational fluctuation is smaller than the set value, it is determined that the glow plug of the cylinder concerned is disconnected, so it is possible to easily and easily disconnect the glow plug while it is still attached to the engine. Can be reliably detected. That is, for example, the engine rotation speed when the glow plug is not disconnected, and the 45 calculated every 45° CA.
``The changing state of the OA engine speed is shown in Figure 2.
On the other hand, if the glow plug of the No. 2 cylinder is disconnected, for example, the ignition of the No. 2 cylinder will not occur at all or will not occur smoothly, so the rotation will increase due to the explosion. disappear or become very small. Therefore, as shown by the broken line B in FIG. 2, the corresponding 211
As the engine speed of the cylinder decreases, its 45°
Maximum value N1)1 and minimum value N(
1 (hereinafter referred to as rotational fluctuation) ΔN1 becomes extremely small. Therefore, since the engine rotational speed or rotational fluctuation has become smaller than the set value, it can be determined that the glow plug of the relevant cylinder has broken. (Example 1) An example of an electronically controlled diesel engine for automobiles in which the method for detecting glow plug breakage of an internal combustion engine according to the present invention is adopted will be described in detail below with reference to the drawings. As shown in the figure, there is a drive shaft 14 that rotates in conjunction with the rotation of the crankshaft of the diesel engine 10, and a feed pump 16 (90 in FIG. 3) fixed to the drive shaft 14 for pumping fuel.
(shown in the unfolded state), a fuel pressure regulating valve 18 for regulating the fuel supply pressure, and a gear 20 fixedly attached to the drive shaft 14
an engine rotation sensor 22 consisting of, for example, an electromagnetic pickup for detecting the rotational state of the diesel engine 10 from the rotational displacement of the engine; a roller ring 25 for driving the pump plunger 24 in cooperation with the face cam 23; a timer piston 26 (FIG. 3 shows 90@expanded state) for controlling the rotational position of the timer piston 26; a timing control valve 28 for controlling the fuel injection timing by controlling the position of the timer piston 26; A timer position sensor 30 made of, for example, a variable inductance sensor for detecting the position of the timer piston 26
, a spill ring 32 for controlling the timing at which fuel is released from the pump plunger 24;
a spill actuator 34 for controlling fuel injection by controlling the position of the spill actuator 34; a spill position comprising, for example, a variable inductance sensor for detecting the 11Vsp of the spill ring 32 from the displacement of the plunger 34A of the spill actuator 34; A sensor 36, a fuel distribution type fuel having a fuel cut solenoid (1:1. below, called FCV) for cutting fuel when the engine is stopped, and a delivery valve 42 for preventing backflow of fuel and preventing backflow. injection pump 12 and the fuel injection pump 1
an injection nozzle 44 for injecting fuel discharged from the second delivery valve 42 into the combustion chamber of the diesel engine 10; and an intake pressure sensor 48 for detecting the pressure of intake air taken in through the intake pipe 46. , an intake temperature sensor 50 for similarly detecting the temperature of intake air, a water temperature sensor 52 disposed on the cylinder 10 of the engine 10 for detecting wetness of engine cooling water, and an accelerator operated by the driver. An accelerator sensor 55 for detecting the depression angle of the pedal 54 (hereinafter referred to as accelerator opening degree) Accp; a glow plug 56 disposed such that its tip protrudes into the engine combustion chamber; and disconnection of the glow plug 56. Warning light 57 for displaying
The injection timing is controlled based on the accelerator opening AOC11 detected from the output of the accelerator sensor 55, the engine rotation speed NE determined from the output of the engine rotation sensor 22, the engine cooling water temperature detected from the output of the water dryness sensor 52, etc. and the controlled injection side amount, so that the fuel of the control injection plow is injected from the Yoki fuel injection pump 12 at the controlled injection timing,
It controls the timing t111111 valve 28, spill actuator 34, etc., and also energizes the glow plug 56 during startup or fast idling to operate it, and further lights up the warning light 57 when a disconnection of the glow plug 56 is detected. Electronic control unit (hereinafter referred to as ECL)
(referred to as I) 58. As shown in detail in FIG. 4, the ECLI 58 includes a central processing unit (hereinafter referred to as CPU) 58A consisting of, for example, a microprocessor for performing various arithmetic operations, a clock 58B for generating various clock signals, and a clock 58B for generating various clock signals. A random access memory (hereinafter referred to as RAM) 58C for temporarily storing calculation data etc. in the CPU 58A, and a read only memory (hereinafter referred to as ROM) 58D for storing control programs and various data etc. , the output of the water temperature sensor 52 inputted via the buffer 58E, the output of the intake temperature sensor 50 inputted via the buffer 58F, the output of the intake pressure sensor 48 inputted via the buffer 58G, and the buffer 58H.
The spill position sensor 36 output ■Sp is driven by the sensor drive frequency signal of the accelerator sensor 55 output and the sensor drive circuit 58J output, and is input via the sensor signal detection circuit 58K. A multiplexer (hereinafter referred to as MP '16) 58N for sequentially taking in the output of the timer position sensor 30, etc., which is driven by the sensor drive frequency signal output from the drive circuit 58L and inputted via the sensor signal detection circuit 58M. and an analog-to-digital converter (hereinafter referred to as A) for converting analog No. 1a of the MPX58N output into a digital signal.
, /D converter) 58P, and the A/DI converter 5
An input/output boat (hereinafter referred to as I10 boat) 58Q for taking in the output of 8P to the CPLJ58A, and an input/output boat 58Q for inputting the output of the engine rotation sensor 22 into the CPLJ58A,
A waveform shaping circuit 58R for directly inputting data into the glow plug 58A, and a waveform shaping circuit 58R for directly inputting the waveform to the glow plug
The drive circuit 58S for energizing 6 and the same ^8 C
The timing control valve 2 according to the calculation result of the PU58A.
The spill position of the CPU 58A output and the spill position sensor 36 output, which are converted into analog signals by a drive circuit 58T for driving 8 and a digital-to-analog converter (hereinafter referred to as a D/A converter) 58U, is signal V
The spill actuator 34 according to the deviation from sp.
Servo amplifier 58V and drive circuit 58 for driving
A common bus 5 for connecting W and each component device.
It consists of 8X. The effects of the embodiment will be explained below. The glow plug IS determination in this embodiment is performed according to the flowchart shown in FIG. That is, first, in step 110, it is determined whether the glow plug 56 is in a state in which it should be operated, for example, during startup or fast idle. This determination is based on the CPLJ58A
calculates the operating time of the glow plug 56, so for example, if the operating signal is not zero, the glow plug 56
6 can be determined to be the state in which it should be operated. If the determination result in step 110 is positive, the process proceeds to step 112, where the engine coolant mTHW determined from the output of the water temperature sensor 52 is set to a set value, for example -2.
Determine whether the temperature is higher than 5°C. This step 11
2 is provided to prevent erroneous judgments at extremely low temperatures when the fuel becomes waxy and normal combustion or ignition cannot be expected. If the determination result in step 112 is positive, the process proceeds to step 114, where the engine rotational speed is set to the set value 11.
For example, it is determined whether the speed is higher than 400 RPM. This step 114 is for preventing erroneous determination at the initial stage of startup when the fuel is not sufficiently ignited. If the judgment result in step 114 is positive, the process proceeds to step 116, where the difference between the maximum 1i1N old and the minimum engine rotational speed per 45" OA and the minimum value Nβi is calculated as shown in the following equation:
That is, the rotational variation ΔN1 is calculated. ΔNl=Nbl-Nil (1) Here, 1 is the cylinder number. Next, the process proceeds to step 118, where the calculated rotational fluctuation ΔN1 for each cylinder is set to a set value, for example, 50 RP.
Determine whether it is greater than M. If the determination result is positive, that is, if it is determined that the rotation has increased sufficiently due to the explosion and the glow plug 56 is operating normally, this routine is immediately terminated. On the other hand, if the determination result in step 118 is negative,
That is, when it is determined that the glow plug 56 of the No. 1 cylinder is disconnected, the process proceeds to step 120, and the warning light 5 is turned on.
7 is turned on to notify the driver of the abnormal condition, and this routine ends. On the other hand, if the determination result in steps 110, 112 or 114 is negative, and it is determined that the determination is not suitable for glow plug disconnection determination, this routine is immediately terminated. In this embodiment, since the rotational variation ΔN1 for each cylinder becomes smaller than the set value, it is determined that the glow plug is disconnected. Therefore, regardless of the overall variation in the engine rotational speed itself, It is possible to accurately determine whether a glow plug is disconnected. Note that the method for determining whether the glow plug is disconnected is not limited to this, and for example, it is also possible to directly determine from a decrease in the rotational speed when the average rotational speed is stable, such as in an idling state. In the above embodiments, the present invention was applied to an electronically controlled diesel engine in which glow plugs were activated during startup and fast idle, but the scope of application of the present invention is not limited to this, and It is clear that the present invention can be similarly applied to an electronically controlled diesel engine, a general diesel engine, and even a gasoline engine, in which a glow plug is operated at all times during engine operation in order to improve the ignitability of the fuel. 1. Effects of the Invention 1 As explained above, according to the present invention, disconnection of a glow plug can be easily and accurately detected while the glow plug remains installed in the engine. Therefore, it has the excellent effect of enabling quick and accurate repair.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the glow plug disconnection detection method for an internal combustion engine according to the present invention, and FIG. FIG. 3, which comparatively shows changes in speed and rotational fluctuations, is a sectional view including a partial block diagram, showing the configuration of an embodiment of an electronically controlled diesel engine for automobiles in which the present invention is adopted; FIG. 4 is a block diagram showing the configuration of the electronic control unit used in the embodiment, and FIG. 5 is a flowchart showing a routine for determining whether the glow plug is disconnected. 10... Engine, 12... Fuel injection pump, 2
2... Engine rotation sensor, 44... Injection nosle, 52... Water temperature sensor, THW... Cooling water temperature, 56
...Glow plug, 57...Warning light, 58...
Electronic control unit (ECLI), Nl+i...45°
Maximum value of engine rotation speed per GA, Nbu1...45°
Minimum value of engine rotation speed per GA, ΔN1...Rotation fluctuation. Agent Takaya Ron (and 1 other person)

Claims (3)

[Claims] (1) In a glow plug disconnection detection method for an internal combustion engine that operates the glow plug at least during startup or fast idling to ensure smooth fuel ignition, it is detected that the glow plug is in a state where it should be activated. When the glow plug is in a state where it should be activated, the procedure for calculating the engine rotation speed or rotation fluctuation for each cylinder.When the engine rotation speed or rotation fluctuation is smaller than the set value, the glow plug for the relevant cylinder is adjusted. A method for detecting a disconnection of a glow plug in an internal combustion engine, the method comprising: a step for determining that a plug is disconnected; (2) A glow plug disconnection detection method for an internal combustion engine according to claim 1, wherein the disconnection determination is not performed when the engine cooling water temperature is extremely low. (3) The method for detecting disconnection of a glow plug in an internal combustion engine according to claim 1, wherein the determination of disconnection is not performed at the beginning of startup when the engine speed is very low.