JP7387274B2 - engine system - Google Patents

Description

The present invention relates to an engine system.

Conventionally, a plasma reactor has been known as a device for decomposing harmful components such as particulate matter (PM) contained in exhaust gas. A plasma reactor generates plasma between a pair of electrode panels, and the plasma decomposes harmful components.

In such a plasma reactor, exhaust gas is supplied and the temperature is raised and lowered. Therefore, moisture contained in the exhaust gas may condense in the plasma reactor, and the electrode panel may become wet. The wet electrode panel is dried by continuous supply of exhaust gas (high-temperature gas), but depending on the operating conditions, it may not be able to be sufficiently dried. If the plasma reactor is started with the electrode panel wet with a large amount of water, electrical leakage may occur. Therefore, it is required to detect abnormalities such as electrical leakage in plasma reactors.

A method for detecting electrical leakage in a plasma reactor is, for example, by acquiring the current value applied to the plasma reactor at regular intervals, counting the number of times the current value deviates from a predetermined range due to abnormal discharge (electrical leakage), and calculating the number of counts. An abnormality detection device has been proposed that detects an abnormality when is greater than or equal to a threshold value (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2018-18777

In the above abnormality detection device, an abnormality in the plasma reactor can be detected after the discharge starts by counting the number of times the current value deviates from a predetermined range due to abnormal discharge (current leakage).

However, since an abnormality in the plasma reactor cannot be detected before abnormal discharge (earth leakage) occurs, it is impossible to avoid the occurrence of abnormal discharge and there is a problem that electric leakage cannot be prevented.

The present invention is an engine system that can stop the plasma reactor before the start of discharge when the plasma reactor is wet, and can prevent electrical leakage.

The present invention [1] includes an engine, a battery, a plasma reactor to which electric power is supplied from the battery and decomposes components contained in exhaust gas discharged from the engine, and an electric power supply from the battery to the plasma reactor. A control unit that controls the plasma reactor, and a charge sensor that is connected to the plasma reactor and detects the amount of charge in the plasma reactor, and the control unit is configured to supply electric power to the plasma reactor and start discharging. First, a charge increase coefficient indicating the amount of charge increase per unit time is calculated based on the amount of charge detected by the charge sensor and the energization time from the start of power supply to the plasma reactor, and the charge increase coefficient is calculated based on the charge increase amount per unit time. The engine system includes an engine system that determines that the plasma reactor is wet when the coefficient is greater than or equal to a predetermined value, and stops supplying power to the plasma reactor.

In the engine system of the present invention, after voltage is applied to the plasma reactor and before discharge starts, the amount of electricity is calculated per unit time based on the amount of charge in the plasma reactor and the energization time from the start of power supply to the plasma reactor. A charge increase coefficient indicating the amount of charge increase is calculated. Since the charge increase coefficient before discharge increases depending on the degree of water wetting of the plasma reactor, the degree of water wetting of the plasma reactor can be predicted from the charge increase coefficient.

In the engine system of the present invention, if the charge increase coefficient before discharge is equal to or higher than a predetermined threshold value, it is determined that the plasma reactor is highly wet, and the power supply to the plasma reactor is stopped. do.

In this manner, in the engine system of the present invention, when the plasma reactor is wet, the plasma reactor can be stopped before discharge starts, thereby preventing electrical leakage.

FIG. 1 is a schematic configuration diagram of an embodiment of an engine system of the present invention. FIG. 2 is a charge-time graph for explaining control of one embodiment of the engine system of FIG.

1. Configuration of Engine System As shown in FIG. 1, an engine system 1 is mounted on, for example, a vehicle 100. The engine system 1 includes an engine 2, a battery 3, a plasma reactor 5, a control section 7, and a charge sensor 10.

(1) Engine The engine 2 is arranged, for example, in the engine room of the vehicle 100. The engine 2 is connected to an intake system (not shown) and a fuel injection system (not shown). The intake system and the fuel injection system are controlled by the control section 7. The engine 2 is started and operated by a starter motor (not shown), and is controlled by a control unit 7 based on electrical signals from various sensors (such as a rotation speed sensor) (not shown). Further, the engine 2 has an exhaust pipe 11, and exhaust gas generated in the engine 2 is discharged through the exhaust pipe 11.

(2) Battery The battery 3 is placed, for example, in the engine room of the vehicle 100. Examples of the battery 3 include known secondary batteries such as lead acid batteries, nickel-metal hydride batteries, and lithium ion batteries.

(3) Plasma Reactor The plasma reactor 5 decomposes harmful components contained in the exhaust gas discharged from the engine 2. Electric power is supplied to the plasma reactor 5 from the battery 3.

Specifically, the plasma reactor 5 includes a case (not shown) to which exhaust gas is supplied, and at least one pair of electrode panels (not shown) disposed within the case. The pair of electrode panels includes metal electrodes that face each other at intervals and a dielectric covering the metal electrodes. Further, an electrode panel (not shown) of the plasma reactor 5 is electrically connected to the battery 3 via a power supply wiring 9.

Such a plasma reactor 5 is interposed in the middle of the exhaust pipe 11. That is, the plasma reactor 5 is connected to the engine 2 via the exhaust pipe 11. As a result, exhaust gas discharged from the engine 2 is introduced into the plasma reactor 5.

The plasma reactor 5 is switched between operation and stop by a control unit 7, which will be described later.

More specifically, the power supply device 4 is interposed in the middle of the power supply wiring 9. The power supply device 4 includes, for example, a switch (not shown) and a step-up circuit (such as a flyback converter) not shown, and the switch is electrically connected to the control unit 7 via the signal wiring 6. Ru. By turning on the switch of the power supply device 4, the control unit 7 supplies power from the battery 3 to the plasma reactor 5 via the power supply device 4 (ON state). Moreover, the control unit 7 stops power supply from the battery 3 to the plasma reactor 5 via the power supply device 4 by turning off the switch (OFF state).

When the plasma reactor 5 is in the ON state, power is supplied from the battery 3 to the electrode panels of the plasma reactor 5 via the power supply wiring 9, and discharge occurs between the pair of electrode panels. As a result, the gas between the pair of electrode panels enters a plasma state. That is, plasma is generated within the plasma reactor 5.

In this way, when the plasma reactor 5 (ON state) is operated with a predetermined power (steady operation), harmful components (for example, hydrocarbons (HC), nitrogen oxides, etc.) contained in the exhaust gas introduced into the plasma reactor 5 are (NOx, particulate matter (PM), etc.) are decomposed by the plasma in the plasma reactor 5. The exhaust gas that has passed through the plasma reactor 5 is then discharged to the outside of the vehicle via the exhaust pipe 11.

On the other hand, when the plasma reactor 5 is in the OFF state, the above power is not supplied and no plasma is generated.

(4) Control Unit The control unit 7 controls power supply from the battery 3 to the plasma reactor 5. The control unit 7 is an ECU (Electronic Control Unit) that performs electrical control in the vehicle 100, and includes a CPU, ROM, RAM, and the like. The control unit 7 is connected to the battery 3 via a power supply wiring 13. The control unit 7 is activated by being supplied with electric power from the battery 3 via the power supply wiring 13 when the ignition switch of the vehicle 100 is turned on.

Such a control unit 7 can switch the plasma reactor 5 between an operating state (ON state) and a stopped state (OFF state) while the engine system 1 is in operation.

The control unit 7 also includes a water-wetting determination program (not shown).

The water-wetting determination program is a program for detecting water-wetness of the plasma reactor 5 from the amount of charge of the plasma reactor 5 and the energization time, as will be described later.

More specifically, the water wetness determination program (not shown) is based on the amount of charge of the plasma reactor 5 detected by a charge sensor 10 (described later) and the energization time from the start of power supply to the plasma reactor 5. The charge increase coefficient of the plasma reactor 5 is calculated, and it is determined whether the charge increase coefficient is less than a predetermined threshold value or greater than or equal to a predetermined threshold value. Then, when the charge increase coefficient of the plasma reactor 5 is equal to or greater than a predetermined threshold value (abnormal value), the control unit 7 determines that the plasma reactor 5 is in a water-wet state.

On the other hand, if the charge increase coefficient of the plasma reactor 5 is less than the threshold value (normal value), the control unit 7 determines that the plasma reactor 5 is not wet.

(5) Charge sensor 10
The charge sensor 10 is connected to the plasma reactor 5 via the high-voltage wiring 11 and is a sensor for detecting the amount of charge in the plasma reactor 5.

As the charge sensor 10, a known charge sensor can be used. Examples of methods for detecting the amount of charge using the charge sensor 10 include a method of measuring the current value of the step-up transformer of the power supply device 4 with a current sensor and detecting the integrated amount as the amount of charge of the plasma reactor 5. .

Further, the charge sensor 10 is electrically connected to the control section 7 via the signal wiring 12, so that the detected amount of charge can be input to the control section 7.

2. Operation of Plasma Reactor Operation of the plasma reactor 5 will be explained with reference to FIGS. 1 and 2.

In vehicle 100 , exhaust gas discharged from engine 2 passes through exhaust pipe 11 and is supplied to plasma reactor 5 . As a result, harmful components (for example, hydrocarbons (HC), nitrogen oxides (NOx), particulate matter (PM), etc.) contained in the exhaust gas flow into the plasma reactor 5.

On the other hand, electric power is supplied to the plasma reactor 5 from the battery 3 via the power supply device 4 .

When power is supplied from the battery 3 to the plasma reactor 5 via the power supply device 4, the applied voltage V increases as the energization time t of the switch of the power supply device 4 elapses. Then, when the voltage V applied to the plasma reactor 5 increases, the amount of charge Q of the plasma reactor 5 increases (see FIG. 2).

In this way, in the plasma reactor 5 described above, the applied voltage V increases as the energization time t passes (increases), so in the non-discharge period (described later), the energization time t and the applied voltage V have a proportional relationship. Become. Further, since the amount of charge Q increases as the applied voltage V increases (as the energization time t elapses), the energization time t (applied voltage V) and the amount of charge Q have a proportional relationship.

Thereafter, in the plasma reactor 5 described above, when a predetermined time t has elapsed from the start of energization and a predetermined voltage value is reached, discharge is started between the electrode panels of the plasma reactor 5 (hereinafter referred to as a discharge start point P).

When a discharge occurs between the electrode panels of the plasma reactor 5, plasma is generated within the plasma reactor 5, and harmful components (such as hydrocarbons (HC)) that have flowed into the plasma reactor 5 are decomposed by the plasma (plasma decomposed).

Note that the charge amount Q of the plasma reactor 5 rises more rapidly during discharge (discharge period) than before the start of discharge (non-discharge period), and the above-mentioned proportional relationship between the energization time t and the charge amount Q is resolved.

3. Water Wetting Detection Since the internal temperature of the plasma reactor 5 described above is increased or decreased by supplying exhaust gas, moisture contained in the exhaust gas may condense within the plasma reactor 5, causing the electrode panel to become wet. There are cases. The wet electrode panel is dried by continuous supply of exhaust gas (high temperature gas). However, depending on the operating condition of the engine 2, the electrode panel may not be sufficiently dried, and if discharge is caused in the plasma reactor 5 while the electrode panel is highly wet, electrical leakage may occur.

Therefore, in the above engine system, the water-wet state of the plasma reactor 5 is determined by the following method.

More specifically, in the region before the discharge start point P (non-discharge section), the energization time t and the amount of charge Q have a proportional relationship, as described above.

In such a proportional relationship, the degree of increase in the amount of charge Q with respect to the energization time t (that is, the slope of the linear function graph showing the correlation between the amount of charge Q and the energization time t) depends on the degree of water wetting in the plasma reactor 5. different.

More specifically, for example, as shown by the thick solid line in FIG. The amount of increase in the amount of charge Q per time is relatively small.

On the other hand, as shown by the double-dashed line in FIG. The amount is relatively large.

In other words, if the plasma reactor 5 is in a non-wet state, the amount of charge increase per unit time in the non-discharge period (hereinafter referred to as charge increase coefficient) is relatively small; If there is, the charge increase coefficient in the non-discharge period will be relatively high.

Therefore, in this control, in order to distinguish between a water-wet state and a non-water-wet state, a threshold value of the charge increase coefficient is set in advance, and when the charge increase coefficient is less than a predetermined threshold value, the plasma reactor 5 is non-wet. It is determined that the device is wet. Further, when the charge increase coefficient is equal to or greater than a predetermined threshold value, it is determined that the plasma reactor 5 is in a water-wet state.

More specifically, in the plasma reactor 5 described above, the relationship between the energization start point (t=0) and the discharge start point P is measured in advance, and the time during which no discharge occurs (non-discharge period) is specified. In the non-discharge period, charge increase coefficients at various degrees of water wetting are measured in advance. On the other hand, the ease with which electrical leakage occurs is observed depending on the degree of wetness. Then, the degree of water wetting that is likely to cause electrical leakage is specified, and the charge increase coefficient corresponding to the degree of water wetting is set as a threshold value in the control unit 7.

In such an engine system 1, as described above, during the period from when power is supplied from the battery 3 to the plasma reactor 5 via the power supply device 4 until discharge starts within the plasma reactor 5 (non-discharge section), , the amount of charge Q in the plasma reactor 5 is detected by the charge sensor 10.

Next, in this engine system 1, the control unit 7 determines, based on the amount of charge Q detected by the charge sensor 10 and the energization time t of the switch of the power supply device 4 (the energization time t from the start of power supply). A charge increase coefficient indicating the amount of charge increase per unit time is calculated.

In other words, the charge increase coefficient corresponds to the slope of a linear function graph showing the correlation between the amount of charge Q and the energization time t in the non-discharge period. More specifically, the relational expression between the amount of charge Q and the energization time t in the non-discharge period is expressed as Q=at (a: charge increase coefficient, Q: amount of charge, t: energization time).

Thereafter, in this control, the control unit 7 determines whether the charge increase coefficient of the plasma reactor 5 is equal to or greater than a threshold value. Note that the threshold value of the charge increase coefficient is, for example, 1.5 times the charge increase coefficient in a dry state.

At this time, if it is determined that the charge increase coefficient of the plasma reactor 5 is less than a preset threshold value, the plasma reactor 5 is determined to be in a non-water-wet state. That is, when the charge increase coefficient is less than a predetermined value, it is determined (predicted) that the inside of the plasma reactor 5 is in a dry state or that the amount of moisture that wets the inside of the plasma reactor 5 is very small.

In this case, it is determined that the possibility of electrical leakage is low, and the plasma reactor 5 continues to operate.

On the other hand, when it is determined that the charge increase coefficient of the plasma reactor 5 is greater than or equal to a preset threshold value, the control unit 7 determines that the plasma reactor 5 is wet. That is, when the charge increase coefficient is equal to or greater than a predetermined value, it is determined (predicted) that there is a large amount of water that wets the inside of the plasma reactor 5.

In this case, it is determined that there is a high possibility of electrical leakage, and the supply of power to the plasma reactor 5 is stopped. As a result, discharge is stopped in the plasma reactor 5, which is in a state where electrical leakage is likely to occur, so that occurrence of electrical leakage is suppressed.

Note that the timing for determining (predicting) the water wet state as described above is not particularly limited as long as the engine system 1 is in operation.

For example, before using the plasma reactor 5 (before exhaust gas purification), power may be supplied to the plasma reactor 5 as a preliminary operation, and the water wet state may be determined by the above control.

Further, for example, when the plasma reactor 5 is used (during exhaust gas purification), power may be supplied to the plasma reactor 5 as a main operation, and the water-wet state may be determined by the above control.

Preferably, before using the plasma reactor 5 (before exhaust gas purification), power is supplied to the plasma reactor 5 as a preliminary operation, and the water wet state is determined by the above control.

4. Effects As described above, in the engine system 1, after voltage is applied to the plasma reactor 5 and before discharge starts, the charge amount Q of the plasma reactor 5 and the energization from the start of power supply to the plasma reactor 5 are determined. Based on the time t, a charge increase coefficient indicating the amount of charge increase per unit time is calculated. Since the charge increase coefficient before discharge increases depending on the degree of water wetting of the plasma reactor, the degree of water wetting of the plasma reactor can be predicted from the charge increase coefficient.

In the engine system 1 described above, when the charge increase coefficient before discharge is equal to or greater than a predetermined threshold value, it is determined that the degree of water wetting of the plasma reactor 5 is high, and power is supplied to the plasma reactor 5. stop.

In this way, in the engine system 1 described above, when the plasma reactor 5 is wet, it is possible to stop the plasma reactor 5 before discharge starts, thereby preventing electrical leakage.

In the plasma reactor 5 described above, the energization time t and the amount of charge Q are in a proportional relationship, but on the other hand, the energization time t and the voltage V applied to the plasma reactor 5 are also in a proportional relationship. That is, the applied voltage V increases as the energization time t elapses, and the applied voltage V and the amount of charge Q are in a proportional relationship.

Therefore, the capacitance C, which is a proportionality constant between the applied voltage V and the amount of charge Q, shows the same tendency as the charge increase coefficient described above. Specifically, the capacitance C is Varies depending on degree of wetness.

Therefore, in the plasma reactor 5 described above, it is necessary to measure the amount of charge Q and the applied voltage V, calculate the capacitance C, and judge whether the capacitance C is greater than or equal to a predetermined value or less than a predetermined value. For example, it is also possible to determine whether the plasma reactor 5 is wet or not wet.

However, in order to actually measure the voltage V applied to the plasma reactor 5, an expensive measuring device such as a high voltage probe is required, which increases the cost of the engine system 1.

On the other hand, in the above engine system, it is determined whether the plasma reactor 5 is wet or not wet by calculating the charge increase coefficient based on the amount of charge Q and the energization time t. Therefore, there is no need to measure the voltage V applied to the plasma reactor 5. In other words, there is no need for expensive measuring equipment, making it highly cost-effective.

1 Engine System 2 Engine 3 Battery 5 Plasma Reactor 7 Control Unit 10 Charge Sensor

Claims (1)

engine and
battery and
a plasma reactor that is supplied with electric power from the battery and decomposes components contained in exhaust gas discharged from the engine;
a control unit that controls power supply from the battery to the plasma reactor;
a charge sensor that is connected to the plasma reactor and detects the amount of charge as an integrated current in the electric power supplied to the plasma reactor;
The control unit includes:
In a non-discharge period before electric power is supplied to the plasma reactor and discharge starts,
Calculating a charge increase coefficient indicating the amount of charge increase per unit time based on the amount of charge detected by the charge sensor and the energization time from the start of power supply to the plasma reactor;
In a non-discharge period of the plasma reactor, if the charge increase coefficient is equal to or greater than a predetermined value, it is determined that the plasma reactor is wet, and the supply of power to the plasma reactor is stopped;
The charge increase coefficient is characterized in that it indicates the degree of increase in the amount of charge as a cumulative amount of current in the power supplied to the plasma reactor with respect to the energization time during which power was supplied to the plasma reactor. engine system.

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