JPH08312515A - Control device of glow plug for methanol engine - Google Patents

Abstract

PURPOSE: To sufficiently secure ignitability at the time of driving an engine by controlling in accordance with a first control value at the time when the first control value of supply electric power to a glow plug at target temperature in accordance with glow plug temperature is higher than a second control value of supply electric power to the glow plug in correspondence with a driving state. CONSTITUTION: A glow plug driving circuit 8 is constituted. A voltage difference between voltage of a resistance sensor 802 having a function as a glow plug temperature detection means and standard voltage is computed by a comparator 803, and a resistance value is computed from it and an electric current value. Thereafter, a first control value τ1 equivalent to resistance is set from a first electric power supply map to memorize supply electric power with a glow plug 6 as target temperature as the first control value τ1. Thereafter, the number of rotation of an engine Ne and a load L are read, and supply map to memorize supply electric power to the glow plug corresponding to a driving state as the second control value τ2. Thereby, by comparing the first and second control values τ1, τ2 with each other, the target value is set as the second control value τ2 when τ2>=τ1, and the target value is set as the first control value τ1 when τ2<τ1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glow plug control device for assisting ignition of an internal combustion engine adopting a compression ignition system, and more particularly to a glow for a methanol engine suitable for a diesel engine type methanol engine for compression ignition of methanol fuel. The present invention relates to a plug control device.

[0002]

2. Description of the Related Art An internal combustion engine that employs a compression ignition system, particularly a diesel engine type methanol engine that uses methanol fuel, has a glow plug for heating fuel particles in a fuel spray region where fuel particles are scattered from an injector. Is installed to ensure ignitability. This type of methanol engine
When the exhaust temperature is low, the activation of the oxidation catalyst is delayed and the emission of formaldehyde and HC tends to increase.
Since the temperature of the combustion chamber is relatively low even after warming up, firstly, it is necessary to secure the ignitability, and the ignition assistance by the glow plug is important. The ignition assist by the glow plug has been performed by constantly applying a constant voltage when the engine key is turned on, but in this case, power supply may be wasted.

In order to reduce such waste, there is, for example, a glow plug control device for a constantly energized methanol engine as shown in FIG. In this glow plug control device, a switch transistor 103 is arranged between a glow plug 100 and a power source 102, and the glow plug 100 is incorporated in a Wheatstone bridge circuit 104.
Reference voltage point 105 in Wheatstone bridge circuit 104
And the voltage difference between the applied voltage point 106 of the glow plug 100 and the comparator 107 are detected by the comparator 107, and the output of the comparator 107 is applied to the switch transistor 103. In addition,
Reference numeral 108 is a sensing register for temperature correction,
Reference numerals 109 and 110 are voltage dividing resistors.

As shown in FIG. 15, a glow plug 100 is provided.
The temperature of is almost proportional to the increase of the resistance value of the glow plug 100. Therefore, in the normal time, the reference voltage point 105
When the applied voltage point 106 is set to a low voltage and the switch transistor 103 is turned on, the resistance increases when the temperature of the glow plug 100 rises excessively, and the applied voltage point 106 becomes higher than the reference voltage point 105. 10
7 outputs an OFF output to close the switch transistor 103 and cut off the current supply, whereby the temperature of the glow plug 100 can be kept constant. On the other hand, JP-A-59-
In Japanese Patent No. 54774, a semiconductor switch is arranged between a power source and a glow plug, and the interruption ratio of the semiconductor switch is changed in relation to the engine temperature so that the electric power supplied to the glow plug has a necessary and sufficient value. What controls is disclosed.

[0005]

However, in the case of the glow plug control device shown in FIG. 14, the control is performed after assuming that the resistance of the glow plug 100 rises in proportion to the temperature. For this reason, when the glow plug itself is deteriorated over time, or the influence of the harness resistance other than the plug, the contact resistance, etc. is received as a disturbance, the resistance increases even though the temperature does not rise, and the power supplied to the glow plug is reduced. I will end up. If such a state occurs, there is a problem in that the glow plug of the engine cannot hold the necessary temperature, and sufficient ignition assistance cannot be provided. On the other hand, in Japanese Patent Laid-Open No. 59-54774, a semiconductor switch is arranged between a power source and a glow plug, and the interruption ratio of the semiconductor switch is changed in relation to the engine temperature.
It is disclosed that the electric power supplied to the glow plug is controlled to a necessary and sufficient value. Also in this case, there is a problem that the engine temperature sensor, its harness resistance, contact resistance, and the like are easily affected by disturbance, and similarly, sufficient ignition assistance cannot be performed.

In addition to such influences of the harness resistance and contact resistance of the glow plug, ignition assist is not available in some cylinders at a glow plug temperature preset due to the operating conditions of the vehicle and the influence of the outside air temperature. It was enough and could lead to misfire.

When the ignition assistance of the glow plug becomes unstable or becomes insufficient as described above and the engine misfires intermittently, it is necessary to perform the ignition assistance with high responsiveness to avoid the misfire. Improvement is desired.

A first object of the present invention is to provide a reliable control of a glow plug for a methanol engine, which can sufficiently secure the ignitability during engine operation, eliminate erroneous control due to disturbance, and have excellent transient response characteristics. To provide a device.

A second object of the present invention is to provide a glow plug control device for a methanol engine, which is capable of assisting ignition in order to avoid misfire during unstable combustion such as engine misfire.

[0010]

In order to achieve the above object, the invention according to claim 1 is a glow plug provided in a cylinder head of an engine and interposed in a fuel injection region injected from a fuel injection valve, A glow plug temperature detecting means for detecting a temperature of the glow plug, an operating state detecting means for detecting an operating state of the engine, and a first control value for storing power supplied to the glow plug as a target temperature.
The electric power supply map, the second electric power supply map storing the electric power supplied to the glow plug corresponding to the operating state detected by the operating state detecting means as the second control value, and the first electric power supply map A control value comparison unit that compares the first control value with the second control value obtained from the second power supply map, and the control value comparison unit determines that the first control value is greater than or equal to the second control value. A first temperature control means for controlling the power supply of the glow plug based on the first control value when it is turned on, and for controlling the power supply of the glow plug based on the second control value otherwise. It is characterized by that.

According to a second aspect of the present invention, in the control device for a glow plug for a methanol engine according to the first aspect, the glow plug temperature detecting means includes a resistance sensor for detecting the resistance of the glow plug, and the same resistance sensor. The temperature of the glow plug is detected based on the detected resistance value and the correlation between the temperature and the resistance of the glow plug.

According to a third aspect of the present invention, in the control device for a glow plug for a methanol engine according to the first or second aspect, the operating state detecting means includes at least a rotation sensor for detecting the rotation speed of the engine, The second control value of the second power supply map is set to correspond to at least the number of rotations detected by the rotation sensor.

According to a fourth aspect of the present invention, a warm-up completion judgment is made based on a glow plug provided in a cylinder head of the engine and interposed in a fuel injection region injected from a fuel injection valve, and the engine temperature of the engine. Determination means, engine combustion state detection means for detecting unstable combustion of the engine, first power supply map for storing supply power with the glow plug as a target temperature as a first control value, warm-up completion determination means for warming After it is determined that the machine is complete, the engine has a misfire determination unit that determines the engine misfire state based on the combustion state detected by the engine combustion state detection means, and the misfire determination unit has determined that the engine misfire state. At this time, the second temperature for controlling the power supply of the glow plug by increasing the first control value obtained by the first power supply map by a predetermined amount. Control means, characterized by comprising a.

According to a fifth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fourth aspect, the misfire determination section has an operating state detecting means for detecting an operating state of the engine, and the engine combustion is performed. The engine misfire state is determined based on the combustion state detected by the state detecting means and the operating state detected by the operating state detecting means.

According to a sixth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fifth aspect, the misfire determination section is the catalyst temperature of the catalyst interposed in the exhaust passage of the engine, or the downstream side thereof. An exhaust temperature detecting means including a first temperature sensor for detecting a downstream side exhaust temperature, and a catalyst temperature or a downstream side exhaust temperature detected by the first temperature sensor is detected by the operating state detecting means. An engine misfire is determined when the first reference temperature based on the state is exceeded.

According to a seventh aspect of the present invention, in the control device for a glow plug for a methanol engine according to the sixth aspect, the exhaust gas temperature detecting means detects a second exhaust gas temperature upstream of the catalyst. And an exhaust gas temperature comparison unit that calculates a deviation between one of the catalyst temperature or the downstream exhaust gas temperature detected by the first temperature sensor and the upstream exhaust gas temperature detected by the second temperature sensor, An engine misfire is determined when the exhaust gas temperature difference value calculated by the temperature comparison unit exceeds a second reference temperature based on the operating condition detected by the operating condition detecting means.

According to an eighth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the sixth to seventh aspects, the first and second reference temperatures are rotations of the engine detected by the operating state detecting means. It is characterized in that each is set based on the number and the load.

According to a ninth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fifth aspect, the misfire determination section has an in-cylinder pressure sensor for detecting the pressure in the combustion chamber of the engine, An engine misfire is determined when the in-cylinder pressure detected by the in-cylinder pressure sensor is less than a reference pressure based on the operating condition detected by the operating condition detecting means.

According to a tenth aspect of the invention, in the glow plug control device for a methanol engine according to the fifth aspect,
The misfire determination unit has a rotation fluctuation sensor that detects a rotation fluctuation component of the engine, and the rotation fluctuation component detected by the rotation fluctuation sensor is a reference rotation fluctuation based on the operating condition detected by the operating condition detecting means. It is characterized in that it is judged as an engine misfire when it does not meet.

The invention according to claim 11 is the glow plug control device for a methanol engine according to claim 5,
The misfire determining unit has an O ₂ sensor for detecting the oxygen concentration in the exhaust passage of the engine, said O ₂ detected oxygen concentration by the sensor is, the reference oxygen based on the operating state detected by the operating condition detecting means The feature is that engine misfire is determined when the concentration is exceeded.

[0021]

According to the invention of claim 1, a glow plug provided in a cylinder head of an engine and interposed in a fuel injection region injected from a fuel injection valve, glow plug temperature detecting means for detecting a temperature of the glow plug, and an engine Operating state detection means for detecting the operating state of the glow plug, a first power supply map for storing the power supplied with the glow plug as the target temperature as the first control value, and a glow corresponding to the operating state detected by the operating state detection means. A second power supply map that stores the power supplied to the plug as a second control value is compared with a first control value obtained by the first power supply map and a second control value obtained by the second power supply map. And a control value comparison unit that controls the first control value when the first temperature control unit determines that the first control value is greater than or equal to the second control value. Controls power supply of the glow plug can, when other than the controls the power supply of the glow plug based on the second control value. Therefore, a relatively high level of power can be supplied to the glow plug.

According to a second aspect of the present invention, in the glow plug control device for a methanol engine according to the first aspect, the glow plug temperature detecting means detects the resistance of the glow plug by the resistance sensor and the resistance sensor. Since the temperature of the glow plug is detected based on the correlation between the resistance value and the temperature of the glow plug and the resistance, the temperature of the glow plug can be detected relatively easily.

According to a third aspect of the present invention, in the glow plug control device for a methanol engine according to the first or second aspect, the operating state detecting means includes at least a rotation sensor for detecting the number of revolutions of the engine, and the second electric power. Since the second control value of the supply map is set at least in correspondence with the rotation speed detected by the rotation sensor, the second control value can be obtained relatively easily.

According to a fourth aspect of the present invention, the warm-up completion determination for determining the warm-up completion is made based on the glow plug provided in the cylinder head of the engine and interposed in the fuel injection region injected from the fuel injection valve, and the engine temperature of the engine. Means, engine combustion state detection means for detecting unstable combustion of the engine, first power supply map for storing supply power with the glow plug as the target temperature as the first control value, and warm-up completion determination means for determining completion of warm-up And a misfire determination section that determines the engine misfire state based on the combustion state detected by the engine combustion state detection means. Particularly, when the misfire determination section determines that the engine misfire state is The temperature control means increases the first control value obtained from the first power supply map by a predetermined amount to control the power supply to the glow plug. For this reason, the second temperature control means can correct the first control value by a predetermined amount at the time of misfire to supply a relatively high level of power to the glow plug.

According to a fifth aspect of the invention, in the control device for a glow plug for a methanol engine according to the fourth aspect, the misfire determination section has an operating state detecting means for detecting an operating state of the engine, and the engine combustion state detecting means. Since the engine misfire state is determined based on the combustion state detected by the above and the operating state detected by the operating state detecting means, the misfire can be determined relatively reliably by a plurality of information.

According to a sixth aspect of the present invention, in the glow plug control device for a methanol engine according to the fifth aspect, the misfire determination unit is the catalyst temperature of the catalyst interposed in the exhaust passage of the engine, or the downstream side thereof. First to detect the side exhaust temperature
A first temperature sensor having an exhaust gas temperature detecting means including a temperature sensor, wherein the catalyst temperature or the lower exhaust gas temperature detected by the first temperature sensor is based on the operating state detected by the operating state detecting means;
The engine misfire is determined when the temperature exceeds the reference temperature (for example, when the unburned fuel burns to a high temperature in the catalyst), and thus the misfire can be determined relatively reliably based on the exhaust temperature information.

According to a seventh aspect of the invention, in the glow plug control device for a methanol engine according to the sixth aspect, the exhaust temperature detecting means detects the upstream exhaust temperature upstream of the catalyst, and Includes an exhaust temperature comparison unit that calculates a deviation between one of the catalyst temperature or the downstream exhaust temperature detected by the first temperature sensor and the upstream exhaust temperature detected by the second temperature sensor, and is calculated by the exhaust temperature comparison unit The determined exhaust gas temperature difference value exceeds the second reference temperature based on the operating condition detected by the operating condition detecting means (for example,
When the unburned fuel burns to a high temperature in the catalyst), it is determined that the engine is misfired. Therefore, the misfire is relatively reliably determined by a plurality of pieces of information of the exhaust temperature information and the second reference temperature based on the operating state. You can do it.

According to an eighth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the sixth aspect, the first and second reference temperatures are the engine speed and the engine speed detected by the operating state detecting means. Since each setting is made based on the load, misfire determination is facilitated.

According to a ninth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fifth aspect, the misfire determination section has an in-cylinder pressure sensor for detecting the pressure in the combustion chamber of the engine. When the in-cylinder pressure detected by the pressure sensor is less than the reference pressure based on the operating state detected by the operating state detecting means (for example, when there is no misfire and no explosive combustion, and the pressure rise is small), it is determined as engine misfire. Therefore, the misfire can be determined relatively reliably and easily by the cylinder pressure information.

According to a tenth aspect of the present invention, in the glow plug control device for a methanol engine according to the fifth aspect,
The misfire determination unit has a rotation fluctuation sensor that detects a rotation fluctuation component of the engine, and the rotation fluctuation component detected by the rotation fluctuation sensor is less than the reference rotation fluctuation based on the operating condition detected by the operating condition detecting means ( For example, if a rotation fluctuation that may otherwise occur due to a misfire in a certain cylinder is not detected), it is determined that the engine is misfired.
The misfire can be determined relatively reliably and easily by the rotational fluctuation component of the engine.

The invention of claim 11 is the glow plug control device for a methanol engine according to claim 5,
Misfire determining unit has an O ₂ sensor for detecting the oxygen concentration in the exhaust passage of the engine, O ₂ detected oxygen concentration by sensors exceeds a reference oxygen concentration based on the detected operating state by the operating state detecting means ( For example, when the oxygen concentration gradually decreases from the low load region to the high load region, but when the engine misfires when the engine misfires and the oxygen concentration is high), the misfire determination is relatively reliable based on the oxygen concentration information. Can be done.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The control unit Ma for a glow plug for a methanol engine of FIG. 1 is installed in an in-line four-cylinder methanol engine (hereinafter simply referred to as an engine) 1. The first cylinder will be mainly described here because each cylinder has the same configuration. Here, the engine 1 is provided with a combustion chamber C for each cylinder, and the combustion chamber C is configured to have a variable volume by a cylinder block 2, a cylinder head 3, and a piston 4 that slides in the cylinder block. A fuel injection valve 5 and a glow plug 6 are mounted on the cylinder head 3, and both are arranged opposite to the combustion chamber C. Here, the fuel injection valve 5 is connected to the fuel injection pump 7, and the glow plug 6 is connected to the glow plug control circuit 8.

On the other hand, the intake passage IR of the engine 1 is formed by an intake pipe 9 connected to the cylinder head 3 and an air cleaner (not shown) arranged at the tip end of the pipe, and the exhaust passage ER is formed by an exhaust pipe 10 and an oxidation catalyst. 11 and a muffler (not shown). An intake throttle valve 12 is provided in the middle of the intake pipe 9, and the valve can hold the intake passage IR at a predetermined opening between fully closed and fully opened. The intake throttle valve 12 is connected to an air switching means 13 provided with an actuator (not shown) capable of increasing / decreasing the valve opening degree stepwise. A controller 14 is connected to the air switching means 13 as a control means for outputting a control signal for switching the valve opening.

The oxidation catalyst 11, which is the main exhaust gas purification device equipped in the exhaust system, has a sufficient capacity to reliably purify engine exhaust gas in a steady state. It should be noted that the oxidation catalyst 11 requires a predetermined time to complete activation at the time of starting. Therefore, a warm-up catalyst (not shown) having a small capacity is arranged upstream of the oxidation catalyst 11, and the warm-up catalyst is configured to perform exhaust gas purification until the activation of the oxidation catalyst 11 is completed.

A second temperature sensor 15 forming an essential part of exhaust gas temperature detecting means is provided on the upstream side of the oxidation catalyst 11, and a first temperature sensor 16 is provided on the downstream side.
Connected to the controller 14, and the controller 14 is connected to the second and first exhaust temperature T
_Can output _ex2 and T _ex1 signals. The fuel injection pump 7 that supplies fuel to the fuel injection valve 5 is connected to the controller 14,
The fuel injection amount and injection timing are controlled. As shown in FIGS. 1 and 3, a glow plug drive circuit 8 and a controller 14 are connected to the glow plug 6.

As shown in FIG. 3, the glow plug drive circuit 8 has a structure in which the glow plug 6 and the power source B are connected, and a switch transistor 801 and a resistance sensor 802 for detecting the resistance of the glow plug 6 are connected in series. take. The resistance sensor 802 has a function as glow plug temperature detecting means for detecting the temperature of the glow plug. The resistance sensor 802 includes a Wheatstone bridge circuit, in which a reference voltage point p1 and an applied voltage point p2 are provided, and both points p1 and p2 are provided.
Is connected to the comparator 803, and the output terminal of the comparator 803 is connected to the controller 14.

The comparator 803 has a voltage Vn at the applied voltage point p2 of the glow plug 6 and a voltage Vb at the reference voltage point p1.
The voltage difference Δv (= Vn−Vb) is detected and the output Δv is transmitted to the controller 14. Switch transistor 801
The target control value τ, which is a duty signal, is applied to the gate terminal of
o is input from the controller 14, and the current I supplied to the glow plug 6 can be interrupted to regulate the power value. FIG.
Among them, reference numeral 804 is a sensing register for temperature correction, and reference numerals 805 and 806 are voltage dividing resistors.

The controller 14 shown in FIG. 1 is constituted by a microcomputer as its main part, and the RO (not shown) is shown.
In M, a flow chart (see FIG. 7) of a later-described glow plug control program, various maps, and set values are stored. A predetermined reference voltage is applied to the controller 14 from the power source B, and further, in addition to the resistance sensor 802 described above, an input / output circuit (not shown) serves as operating state detecting means for detecting various operating state information of the engine. An engine speed sensor 17 for detecting the engine speed Ne, a load sensor 18 for detecting a load L which is a lever opening (not shown) of the fuel injection pump 7, a key sensor 19 for outputting a key signal Sk of an engine key, and an engine water temperature Tw. The water temperature sensor 20, the second temperature sensor 15 and the first temperature sensor 16 described above are connected to each other.

Here, the controller 14 of FIG. 1 has the following functions. That is, the controller 14 of FIG.
A glow plug temperature detecting means 14a, an operating state detecting means 14b for detecting the operating state of the engine in cooperation with the above-mentioned sensors, a first power supply map m1 (see FIG. 6),
The second power supply map m2 (see FIG. 4), the control value comparison unit 14c, and the functions of the first temperature control unit 14d are provided (see functional blocks in FIG. 2).

Here, the glow plug temperature detecting means 14a
Detects the resistance Rg of the glow plug by the resistance sensor 802. In this case, the above-mentioned voltage difference Δv (= Vn-V
b) is taken in to obtain the current value In (the current value is calculated as τ × i from the current duty ratio% τ and the coefficient i), and the Δv and In are used to follow the resistance value calculation map m3 in FIG. Resistance of the glow plug 6, for example resistance Rg
1 and 2 are calculated. Furthermore, the first power supply map m in FIG.
A first control value τ1 corresponding to the current resistance Rg is calculated according to 1.

The first power supply map m1 (not shown) is
Set the glow plug 6 to the target temperature Tgo (the same temperature and the resistance value Rg
The supply power of which is proportional to o) is stored as the first control value τ1. That is, the first control value τ1 is the current resistance value Rg.
Can be corrected to a predetermined value Rgo (the temperature of the glow plug corresponding to this resistance value is preset as an appropriate temperature). Here, the first control value τ1 is a time width (duty ratio) for intermittently restricting the current flowing through the glow plug 6 receiving the applied voltage of the power source B. The larger the value (duty ratio%), the larger the current value. I becomes large.

The second power supply map m2 stores the power supplied to the glow plug corresponding to the engine speed Ne and the operating condition of the load L as the second control value τ2 (duty ratio). As shown in FIG. 4, the second control value τ2 here is preset according to the engine speed Ne and the engine load L, and can be calculated from the current engine speed Ne and the engine load L. The second control value τ2 is set to increase according to the increase in the rotation speed. The control value comparison unit 14c compares the first control value τ1 obtained from the first power supply map m1 with the second control value τ2 obtained from the second power supply map m2.

The first temperature control means 14d is the control value comparison unit 1
4a, when it is determined that the first control value τ1 is greater than or equal to the second control value τ2, the power supply to the glow plug 6 is controlled based on the first control value τ1, and otherwise the second control value τ2 is set. Based on this, the power supply of the glow plug is controlled. Here, the operation of the present apparatus will be described with reference to the flowchart of the glow plug control program in FIG. The controller 14 enters control of a main routine (not shown) by inputting a key-on signal, and reaches a glow plug control program at a predetermined time. At step s1, Δv (= Vn−V
b), current value In (= τ × i) is calculated, and Δv and In
The resistance Rg of the glow plug 6 is calculated according to the resistance value calculation map m3 of FIG. 5, and then the first power supply map m
1, the first control value τ1 corresponding to the resistance Rg is set.

At step s2, the engine speed Ne and the load L are fetched and Ne,
The second intermittent signal τ2 corresponding to L is calculated. In steps s3 to s5, the magnitudes of the first control value τ1 and the second control value τ2 are compared, the target control value τo is set to the second control value τ2 when τ2 ≧ τ1, and the target control value τo is set to the second control value τo when τ2 <τ1. 1 Control value τ1. After that, when step s6 is reached, here, the switch transistor 801 is driven based on the target control value τo at this time, the amount of current supplied to the glow plug 6 is adjusted, and the process returns to the main routine (not shown).

As described above, the control unit for the glow plug for a methanol engine of FIG. 1 obtains the second control value τ2 corresponding to the first control value τ1 and the rotation speed Ne detected by the engine rotation sensor 17, and then calculates the second control value τ2. The actual value of the glow plug obtained by the resistance sensor 802 can be adjusted to the target temperature Tgo by setting the larger value among them as the target value. For this reason, reliable ignition assistance can be performed when necessary, and reliability against misfire is improved,
Moreover, the second control value can be obtained relatively easily, and the configuration of the device can be simplified. FIG. 8 shows a functional block of a control device Mb for a glow plug for a methanol engine, which is a second embodiment of the present invention.

Here, the control device Mb of the glow plug for a methanol engine includes many of the same members except that the control configuration of the control device Ma of the glow plug for a methanol engine of FIG. The same members are designated by the same reference numerals, and duplicate description is omitted. Here, in the control device Mb of the glow plug for a methanol engine, the controller 14b has the following functions in place of the controller 14 of FIG. That is, the controller 14b of FIG. 8 includes a glow plug temperature detecting means 14a, an operating state detecting means 14b that cooperates with the above-described sensors to detect an operating state of the engine, a first power supply map m1, and a second power supply map. As the power supply map m2, the control value comparison unit 14c, the first temperature control unit 14d, the warm-up completion determination unit 14e, the engine combustion state detection unit 14f, the misfire determination unit 14g, and the second temperature control unit 14h. With each function of.

Here, in particular, the warm-up completion determining means 14e determines the completion of warm-up based on the engine temperature of the engine (warm-air completion temperature Tw1). Engine combustion state detecting means 14
f detects unstable combustion of the engine. Misfire determination unit 14
Basically, g determines the engine misfire state based on the combustion state detected by the engine combustion state detection means 14f after the warm-up completion determination means 14e determines that the warm-up is completed.

In this case, in particular, the misfire determination unit 14g is provided with the catalyst temperature of the catalyst 11 provided in the exhaust passage ER of the engine,
Or an exhaust temperature detecting means including a first temperature sensor 16 for detecting a downstream exhaust temperature on the downstream side thereof, and one of the catalyst temperature or the downstream exhaust temperature detected by the first temperature sensor and the operating state detecting means. 14b-the first reference temperature based on the operating state detected by 14b
The engine misfire is determined when the temperature exceeds the first reference temperature. In addition, the exhaust temperature detecting means detects the upstream exhaust temperature upstream of the catalyst, and the second temperature sensor 15 and one of the catalyst temperature or the downstream exhaust temperature detected by the first temperature sensor 16, and the second temperature. A deviation from the upstream exhaust temperature detected by the sensor 15 is calculated, and the deviation is calculated by the second exhaust temperature comparison unit 14g-2 and the second reference temperature based on the operating condition detected by the operating condition detecting means 14b. Comparison is made, and when the deviation exceeds the second reference temperature, engine misfire is determined. Here, the first and second reference temperatures are respectively set on the basis of the engine speed Ne and the load L detected by the operating state detecting means 14b.

The second temperature control means 14h includes the misfire determination section 14
When it is determined that the engine is in the misfire state in g,
The first control value τ obtained from the first power supply map m1
1 is increased by a predetermined amount to control the power supply of the glow plug.

The operation of the controller Mb will be described below with reference to the flow chart of the glow plug control program shown in FIG. The controller 14b enters control of a main routine (not shown) by inputting a key-on signal, and reaches a glow plug control program at a predetermined time. Steps a1 and a
In Fig. 2, Δv and In are obtained, and based on these values, Figs.
The resistance R of the glow plug 6 along the resistance calculation map m3 of
g is calculated, and then the first control value τ1 corresponding to the resistance Rg is set along the first power supply map m1. Furthermore,
The engine speed N along the second power supply calculation map m2
The second control value τ2 corresponding to e and the load L is calculated.

In steps a3 to a5, the first control value τ
1 is compared with the second control value τ2, and the target control value τo is τ2.
The second control value τ2 is set when ≧ τ1, and the first control value τ1 is set when τ2 <τ1. After that, when step a6 is reached, it is determined here whether or not the engine water temperature Tw exceeds the warm-up completion temperature Tw1. If not, the process proceeds to step a11. When steps a7 and a8 are reached after warming up, the first temperature sensor 16 detects the first exhaust temperature T _ex1 on the downstream side of the exhaust passage of the catalyst 11 and is preset according to the current engine speed Ne and the load L. It is determined whether the first exhaust temperature T _ex1 exceeds the abnormal exhaust temperature T2. As a result, when it exceeds (T _ex2 ≧ T2), the correction f (T _ex2 −T _ex1 ) of the current supply amount corresponding to the temperature difference (T _ex2 −T _{ex 1} ) is corrected to the target control value τo at this point. On the other hand, the corrected target control value τo is calculated by the following equation (1).

Τo = τo + f (T _ex2 −T _ex1 ) _... (1) On the other hand, the first exhaust temperature T _ex1 is lower than the exhaust temperature T2 (T _{ex1
When ex1} <T2), the process directly proceeds to step a9.

Steps a7 and a8 indicate the function of the engine combustion state detecting means 14f. Here, when unburned HC is generated in the combustion chamber C and flows into the exhaust pipe 10 side and burns there, the temperature in the exhaust passage rises abnormally and exceeds a preset abnormal exhaust temperature T2. It will be. In such a case when combustion is unstable,
Often occurs at misfire. In this case, when the current is supplied to the glow plug 6 in step a11 described later, the increased current is supplied. Steps a9 and a10
Then, the second temperature sensor 15 detects the exhaust temperature T _ex2 of the catalyst 11 on the upstream side of the exhaust passage, and the first temperature sensor 16 detects the first exhaust temperature T _ex1 of the catalyst 11 on the downstream side of the exhaust passage. It is determined whether or not the present second and first exhaust gas temperature difference ΔT (= T _ex2 −T _ex1 ) exceeds an abnormal exhaust gas temperature difference ΔTex preset according to the engine speed Ne and the load L (FIG. 10). reference).

As a result, when it exceeds (ΔT ≧ ΔTex),
The correction of increasing the current supply amount corresponding to the current second and first exhaust gas temperature difference ΔT is performed by the following expression (2) with respect to the target control value τo at this point, and the corrected target control value τo is corrected. _Is obtained, and if it is below (T _ex2 <T2), step a1 is performed as it is.
Go to 1.

Τo = τo + f (ΔT) ... (2) Here, the ignitability in the combustion chamber C decreases, misfire occurs, and the untwisted gas reaches the oxidation catalyst 11, where The combustion increases ΔT, which exceeds a preset abnormal front-rear exhaust gas temperature difference ΔTex. In such a situation, the current second and
Correct the increase in the current supply amount equivalent to the exhaust gas temperature difference ΔT,
When the current is supplied to the glow plug 6 in step a11 described later, the increased current is supplied. After this, step a11 is reached. Here, based on the target control value τo at this time, the switch transistor 801
Is driven to adjust the amount of current supplied to the glow plug 6, and the process returns to the main routine (not shown).

In the above description, the control device Mb of the glow plug for the methanol engine of FIG.
However, instead of this, as a modification of the control device Mb for the methanol engine glow plug, only the control including step a1 and steps a6 to a11 is performed. May be configured as. Further, the control may be configured to simply include step a2 and steps a6 to a11. In these cases as well, the simplified glow plug control device can be performed only for the control after warming up, and the device can be simplified.

In the above description, the control device Mb of the glow plug for the methanol engine has its misfire determination section 14
The engine misfire state is determined based on the combustion state detected by the engine combustion state detection unit 14f after g has been determined to be warmed up by the warmup completion determination unit 14e. Instead of this, the controller 1
4 ', as shown in FIG. 11, steps a2, a5',
It may be configured to execute a6, a9 'to a11. In the case of this modified example, a misfire determination unit (not shown) misfire determination unit 14g ′ has an in-cylinder pressure sensor (shown by a two-dot chain line Sp in FIG. 1) for detecting the pressure in the combustion chamber C of the engine,
The in-cylinder pressure Pc detected by the in-cylinder pressure sensor Sp is
The engine misfire may be determined when the reference pressure Pcα based on the operating state detected by the operating state detecting means 14b is not reached.

Further, as shown in FIG. 12, the controller 14 'controls the steps a2, a5 ", a6, a9" to a1.
It may be configured to execute 1. In the case of this modification, the misfire determination unit (not shown) misfire determination unit 14g ″ has a rotation fluctuation sensor (means for calculating from the crank angle), which is based on the cycle for each predetermined crank angle of each cylinder of the engine. Then, the change rate (fluctuation component) of the engine rotation is detected, and the rotation fluctuation ΔNe component detected by this rotation fluctuation sensor (not shown) is the reference rotation based on the driving condition detected by the driving condition detecting means 14b. When the variation is less than ΔNeα, engine misfire may be determined.

Further, as shown in FIG. 13, the controller 14 'controls the steps a2, a5 "', a6, a9"'through a.
It may be configured to execute 11. In the case of this modification, a misfire determination unit (not shown) misfire determination unit 14g ″ ′ has an O ₂ sensor (shown by a two-dot chain line S _{A / F} in FIG. 1) for detecting the oxygen concentration in the exhaust passage of the engine, When the oxygen concentration A / Fn detected by the O ₂ sensor S _{A / F} exceeds the reference oxygen concentration A / Fb based on the operating condition detected by the operating condition detecting means 14b, it may be judged that the engine is misfiring. As described above, the control device Mb of the glow plug for the methanol engine is replaced with the misfire determination unit 14g, and instead of the misfire determination unit misfire determination units 14g ′, 14g ″, 14
In the case where each of the g "'s is provided, the same operational effect as that of the control device Mb of the glow plug for the methanol engine of FIG.

[0060]

According to the invention of claim 1, a glow plug provided in a cylinder head of an engine and interposed in a fuel injection region injected from a fuel injection valve, and glow plug temperature detecting means for detecting a temperature of the glow plug. Corresponding to the operating state detecting means for detecting the operating state of the engine, the first power supply map for storing the supplied power with the glow plug as the target temperature as the first control value, and the operating state detected by the operating state detecting means. A second power supply map that stores the power supplied to the glow plug as a second control value, a first control value obtained by the first power supply map, and a second control value obtained by the second power supply map. And a control value comparison unit that compares the first control value with the first control value when the control value comparison unit determines that the first control value is greater than or equal to the second control value. Controls power supply of the glow plug based on, except when the controls the power supply of the glow plug based on the second control value. Therefore, a relatively high level of power can be supplied to the glow plug when necessary, reliable ignition assistance can be performed when necessary, and reliability against misfire is improved.

According to a second aspect of the present invention, in the glow plug control device for a methanol engine according to the first aspect, the glow plug temperature detecting means detects a resistance of the glow plug and a resistance sensor for detecting the resistance of the glow plug. Since the temperature of the glow plug is detected based on the correlation between the resistance value and the temperature of the glow plug and the resistance, the temperature of the glow plug can be detected relatively easily, and reliable ignition assistance can be performed when necessary, and a device configuration Can be facilitated.

According to a third aspect of the present invention, in the glow plug control device for a methanol engine according to the first or second aspect, the operating state detecting means includes at least a rotation sensor for detecting the number of revolutions of the engine, and the second electric power. Since the second control value of the supply map is set corresponding to at least the number of revolutions detected by the rotation sensor, the second control value can be obtained relatively easily, and reliable ignition assistance can be performed when necessary, and The configuration can be simplified.

According to a fourth aspect of the present invention, the warm-up completion determination for determining the warm-up completion is made based on the glow plug provided in the cylinder head of the engine and interposed in the fuel injection region injected from the fuel injection valve, and the engine temperature of the engine. Means, engine combustion state detection means for detecting unstable combustion of the engine, first power supply map for storing supply power with the glow plug as the target temperature as the first control value, and warm-up completion determination means for determining completion of warm-up And a misfire determination section that determines the engine misfire state based on the combustion state detected by the engine combustion state detection means. Particularly, when the misfire determination section determines that the engine misfire state is The temperature control means increases the first control value obtained from the first power supply map by a predetermined amount to control the power supply to the glow plug. Therefore, the second temperature control means corrects the first control value by a predetermined amount at the time of misfire to supply a relatively high level of electric power to the glow plug, and at the time of misfire, the power supply capable of responsively avoiding misfire is ensured. Ignition assistance can be performed, and reliability against misfire is particularly improved.

According to a fifth aspect of the invention, in the control device for a glow plug for a methanol engine according to the fourth aspect, the misfire determination section has an operating state detecting means for detecting an operating state of the engine, and the engine combustion state detecting means. Since the engine misfire state is determined based on the combustion state detected by and the operating state detected by the operating state detection means, the misfire can be determined relatively reliably by a plurality of information, and the reliability of the misfire determination is improved. .

According to a sixth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fifth aspect, the misfire determination unit is the catalyst temperature of the catalyst installed in the exhaust passage of the engine, or the downstream of the catalyst. First to detect the side exhaust temperature
A first temperature sensor having an exhaust gas temperature detecting means including a temperature sensor, wherein the catalyst temperature or the lower exhaust gas temperature detected by the first temperature sensor is based on the operating state detected by the operating state detecting means;
When the engine temperature exceeds the reference temperature, it is judged that the engine has misfired, so the misfire can be judged relatively reliably based on the exhaust temperature information.
The reliability of misfire determination is improved.

According to a seventh aspect of the present invention, in the control device for a glow plug for a methanol engine according to the sixth aspect, the exhaust temperature detecting means detects a second exhaust temperature upstream of the catalyst, and Includes an exhaust temperature comparison unit that calculates a deviation between one of the catalyst temperature or the downstream exhaust temperature detected by the first temperature sensor and the upstream exhaust temperature detected by the second temperature sensor, and is calculated by the exhaust temperature comparison unit When the determined exhaust gas temperature difference value exceeds the second reference temperature based on the operating condition detected by the operating condition detecting means, engine misfire is determined, so the misfire determination is determined based on the exhaust temperature information and the operating condition. By using a plurality of pieces of information, the reliability of misfire determination is further improved.

According to an eighth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the sixth or seventh aspect, the first and second reference temperatures are the engine speed and the engine speed detected by the operating state detecting means. Since each is set based on the load, misfire determination is facilitated, and the configuration of an apparatus capable of performing reliable ignition assistance when necessary can be facilitated.

According to a ninth aspect of the present invention, in the control device for a glow plug for a methanol engine according to the fifth aspect, the misfire determination section has an in-cylinder pressure sensor for detecting the pressure in the combustion chamber of the engine. When the in-cylinder pressure detected by the pressure sensor does not reach the reference pressure based on the operating state detected by the operating state detecting means, it is determined that the engine is misfired, so the misfire determination is relatively reliable and easy based on the in-cylinder pressure information. In addition, the reliability of misfire determination is improved, and the device can be simplified.

According to a tenth aspect of the invention, in the glow plug control device for a methanol engine according to the fifth aspect,
The misfire determination unit has a rotation fluctuation sensor that detects a rotation fluctuation component of the engine, and when the rotation fluctuation component detected by the rotation fluctuation sensor is less than the reference rotation fluctuation based on the operating condition detected by the operating condition detecting means. Since the engine misfire is determined, the misfire can be relatively reliably and easily determined by the engine rotation fluctuation component, the reliability of the misfire determination is improved, and the device can be simplified.

The invention of claim 11 is the glow plug control device for a methanol engine according to claim 5,
When the misfire judging section which has an O ₂ sensor for detecting the oxygen concentration in the exhaust passage of the engine, O ₂ detected oxygen concentration by sensors exceeds a reference oxygen concentration based on the detected operating state by the operating state detecting means Since the engine misfire is determined, the misfire can be relatively reliably determined based on the oxygen concentration information, and the reliability of the misfire determination is improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a control device for a glow plug for a methanol engine as an embodiment of the present invention.

FIG. 2 is a functional block diagram of a control device of the glow plug for a methanol engine of FIG.

FIG. 3 is a schematic configuration diagram of a glow plug drive circuit used by the control device for the glow plug for a methanol engine of FIG.

FIG. 4 is a characteristic diagram of a second power supply map used by the control device of FIG.

5 is a characteristic diagram of a resistance calculation map used by the control device of FIG. 1. FIG.

FIG. 6 is a characteristic diagram of a first power supply map used by the control device of FIG.

FIG. 7 is a flowchart of a control program executed by the control device of FIG.

FIG. 8 is a functional block diagram of a glow plug control device for a methanol engine as another embodiment of the present invention.

9 is a flowchart of a control program executed by the control device of FIG.

FIG. 10 is a Ne-exhaust temperature characteristic diagram showing a relationship between a preset abnormal second first exhaust temperature difference and a current second first exhaust temperature difference.

11 is a flowchart of a control program used by the control device of FIG. 8 as a modified example.

FIG. 12 is a flowchart of a control program used by the control device of FIG. 8 as a modified example.

FIG. 13 is a flowchart of a control program used by the control device of FIG. 8 as a modified example.

FIG. 14 is a schematic circuit diagram of a conventional glow plug control device for a methanol engine.

FIG. 15 is a resistance-temperature diagram of a glow plug. 1 Engine 5 Fuel Injection Valve 6 Glow Plug 8 Glow Plug Drive Circuit 801 Switch Transistor 802 Resistance Sensor 11 Oxidation Catalyst 14 Controller 14 'Controller 14a Glow Plug Temperature Detecting Means 14b Operating State Detecting Means 14c Control Value Comparing Section 14d First Temperature Control Means 14e Warm-up completion determination means 14f Engine combustion state detection means 14g Misfire determination part 14h Second temperature control means 14g-1 First exhaust temperature comparison part 14g-2 Second exhaust temperature comparison part 15 Second temperature sensor 16 First temperature sensor 17 engine speed sensor 18 load sensor 19 key switch 20 water temperature sensor τ1 first control value τ2 second control value τo target control value m1 first power supply map m2 second power supply map Δv voltage difference B power supply C combustion chamber ER exhaust passage In Current value IR Intake passage Ma controller Mb controller Tw engine water temperature Rg glow plug resistance

Claims (11)

[Claims] 1. A glow plug provided in a cylinder head of an engine and interposed in a fuel injection region injected from a fuel injection valve, glow plug temperature detecting means for detecting a temperature of the glow plug, and an operating state of the engine. Operating state detecting means, a first power supply map that stores the power supplied to the glow plug as a target temperature as a first control value,
A second power supply map storing the power supplied to the glow plug corresponding to the operating state detected by the operating state detecting means as a second control value, and the first control value obtained by the first power supply map. And a control value comparison unit that compares the second control value obtained by the second power supply map, and the first control value is determined to be greater than or equal to the second control value in the control value comparison unit, First temperature control means for controlling the power supply to the glow plug based on the first control value, and for controlling the power supply to the glow plug based on the second control value at times other than the above. Control device for glow plug for methanol engine. 2. The glow plug temperature detecting means detects the resistance of the glow plug, the glow sensor based on the resistance value detected by the resistance sensor, and the correlation between the temperature and the resistance of the glow plug. 2. The glow plug control device for a methanol engine according to claim 1, wherein the temperature of the plug is detected. 3. The operating state detecting means includes a rotation sensor for detecting at least the rotation speed of the engine, and the second control value of the second power supply map is at least the rotation speed detected by the rotation sensor. The control device for a glow plug for a methanol engine according to claim 1 or 2, wherein the control device is set in accordance with the above. 4. A glow plug provided in a cylinder head of an engine and interposed in a fuel injection region where fuel is injected from a fuel injection valve, warm-up completion determining means for determining warm-up completion based on an engine temperature of the engine, and the engine. Engine combustion state detecting means for detecting the unstable combustion of the engine, a first power supply map for storing the power supplied with the glow plug as a target temperature as a first control value, and the warm-up completion determining means determines that the warm-up is completed. After that, the engine combustion state detecting means determines that the engine has been warmed up, and then the engine combustion state detecting means determines the engine misfire state based on the combustion state. When it is determined that the engine is in the misfire state, the first control value obtained from the first power supply map is increased by a predetermined amount. Serial second temperature control means for controlling the power supply of the glow plug, the control device of the glow plug for methanol engine, comprising the. 5. The misfire determination section has an operating state detecting means for detecting an operating state of the engine, the combustion state detected by the engine combustion state detecting means, and the operation detected by the operating state detecting means. The control device for a glow plug for a methanol engine according to claim 4, wherein the engine misfire state is determined based on the state. 6. The misfire determination section has an exhaust temperature detecting means including a first temperature sensor for detecting a catalyst temperature of a catalyst interposed in an exhaust passage of the engine or a downstream exhaust temperature downstream thereof. An engine misfire is determined when the catalyst temperature or the downstream side exhaust gas temperature detected by the first temperature sensor exceeds a first reference temperature based on the operating condition detected by the operating condition detecting means. Item 6. A glow plug control device for a methanol engine according to Item 5. 7. A second temperature sensor, wherein the exhaust temperature detecting means detects an upstream exhaust temperature upstream of the catalyst, and one of the catalyst temperature or the downstream exhaust temperature detected by the first temperature sensor. And an exhaust gas temperature comparison unit that calculates a deviation from the upstream exhaust gas temperature detected by the second temperature sensor, and an exhaust gas temperature difference value calculated by the exhaust gas temperature comparison unit is detected by the operating state detection unit. The control device for a glow plug for a methanol engine according to claim 6, wherein the engine misfire is determined when the second reference temperature based on the operating state is exceeded. 8. The method according to claim 6, wherein the first and second reference temperatures are respectively set on the basis of the engine speed and the load detected by the operating state detecting means. Control device for glow plug for methanol engine. 9. The misfire determination section has an in-cylinder pressure sensor for detecting the pressure in the combustion chamber of the engine, and the in-cylinder pressure detected by the in-cylinder pressure sensor is detected by the operating state detecting means. The glow plug control device for a methanol engine according to claim 5, wherein the engine misfire is determined when the reference pressure based on the operating state is not satisfied. 10. The misfire determination unit has a rotation fluctuation sensor for detecting a rotation fluctuation component of the engine, and the rotation fluctuation component detected by the rotation fluctuation sensor is an operating condition detected by the operating condition detecting means. 6. The glow plug control device for a methanol engine according to claim 5, wherein the engine misfire is determined when the reference rotation fluctuation based on the above is not satisfied. The method according to claim 11, wherein said misfire determining unit has an O ₂ sensor for detecting the oxygen concentration in the exhaust passage of the engine, driving said O ₂ detected oxygen concentration by the sensor is detected by the operating condition detecting means 6. The glow plug control device for a methanol engine according to claim 5, wherein the engine misfire is determined when the reference oxygen concentration based on the state is exceeded.