JP3577342B2 - Power supply for heating the catalyst - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a catalyst heating power supply device for heating a catalyst carrier having a catalyst component carried on its surface by high frequency induction heating.
[0002]
[Prior art]
In general, when the engine of an automobile or the like is coldly warmed up, the exhaust gas temperature is low and the catalyst temperature is lower than the activation temperature, so that the exhaust gas may not be sufficiently purified. For this reason, various systems have been conventionally proposed in which a catalyst carrier having a catalyst component supported on its surface is heated to promote early activation of the catalyst and improve exhaust gas purification performance.
[0003]
For example, JP-A-3-202614 discloses a technique in which a catalyst carrier made of an electric heating material is energized and heated, and JP-A-2-223622 discloses a catalyst carrier made of a stainless steel honeycomb. There has been disclosed a technique in which a honeycomb body is formed into a shape and electricity is supplied to the honeycomb shape to generate heat.
[0004]
Furthermore, Japanese Utility Model Application Laid-Open No. 3-002303 discloses a technique in which a high-frequency coil for generating an eddy current in a catalyst carrier is provided in a catalytic converter container and the catalyst carrier is heated by high-frequency induction heating. No. 4-335355 discloses a technique for high-frequency induction heating of a catalyst carrier formed of a spirally wound body.
[0005]
[Problems to be solved by the invention]
However, in order to quickly heat the catalyst to the activation temperature at or before the start of the engine and maintain the catalyst at the predetermined temperature until the exhaust gas temperature reaches the activation temperature, it is necessary to supply a predetermined power for a predetermined time. The supplied electric power is a large electric power of several Kw (for example, 4 to 5 Kw) or more, and the current value is as large as several hundred amps in a vehicle-mounted battery power supply.
[0006]
As a result, the power density (output per weight) of a conventional lead battery or the like that involves a chemical reaction is small, so that an attempt to obtain a large power density requires an increase in the size of the battery, which inevitably increases the weight and volume. This causes not only the deterioration of fuel efficiency and the inconvenience of mounting, but also the problem of increased power loss on the way and reduced durability of the battery.
[0007]
The present invention has been made in view of the above circumstances, and efficiently controls power from a battery and supplies it to the catalyst carrier as heating power, thereby reducing power loss, reducing the size of the device, and improving the durability of the battery. It is an object of the present invention to provide a power supply device for heating a catalyst that can be used.
[0008]
[Means for Solving the Problems]
The present invention provides a catalyst heating power supply device for high-frequency induction heating of a catalyst carrier having a catalyst component carried on a surface thereof, wherein the charging means charges the electric double layer capacitor by increasing the voltage of the battery, and is charged by the charging means. The DC voltage from the electric double layer capacitor is converted into an AC voltage , and an induction coil wound around the outer periphery of the catalyst carrier is supplied with a high-frequency current at a resonance frequency via a resonance capacitor connected in series to the induction coil. A high-frequency current applying unit that supplies current; and a catalyst heating control unit that corrects a shift in the resonance frequency of the induction coil by controlling the operation and stop of the high-frequency current applying unit in accordance with the catalyst temperature. .
[0009]
[Action]
In the present invention, the DC voltage from the electric double-layer capacitor charged by boosting the voltage of the battery is converted into an AC voltage, and the induction coil wound around the outer periphery of the catalyst carrier has a high frequency at a resonance frequency via a resonance capacitor. Apply current. By controlling the energization and non-energization of the high-frequency current according to the catalyst temperature, to correct the deviation of the resonance frequency of the induction coil.
[0010]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 shows an embodiment of the present invention, FIG. 1 is a circuit configuration diagram of a power supply device, FIG. 2 is a waveform diagram showing a control operation, and FIGS. 3 (a) and 3 (b) are schematic sectional views of a catalytic converter.
[0011]
In FIG. 3, reference numeral 1 denotes a catalytic converter which is connected to an exhaust system of an engine (not shown) of an automobile or the like and purifies exhaust gas. A catalytic component made of a noble metal or the like is provided in a case 1a of the catalytic converter 1. For example, a catalyst carrier 2 carrying a catalyst component such as platinum or rhodium on its surface is built in, and an induction coil 3 is wound around the outer periphery of the case.
[0012]
The catalyst carrier 2 has a cell structure made of a magnetic material, and the cells are in electrical contact with each other. On the other hand, the case 1a is made of a non-magnetic material such as ceramics so that the magnetic flux generated by the induction coil 3 is concentrated on the internal catalyst carrier 2. In other words, the conventional metal case housing the catalyst carrier and the induction coil is used as a non-magnetic material, and the induction coil is wound around the outer periphery of the case, so that the induction coil is not directly exposed to the exhaust gas to extend the life. .
[0013]
As shown in FIG. 3 (b), a temperature sensor 4 is located downstream of the catalyst carrier 2, and the temperature sensor 4 and the induction coil 3 are connected to a power supply 5 for supplying heating power. It is connected. The temperature sensor 4 is a sensor having a characteristic that the electric resistance is large when the temperature is low and the electric resistance is reduced when the temperature rises. The temperature of the exhaust gas at the catalyst outlet is measured indirectly to detect the catalyst temperature. It is supposed to. The temperature sensor 4 may be attached to a position where the temperature of the catalyst carrier 2 can be measured to detect the catalyst temperature.
[0014]
Then, a high-frequency current is supplied to the induction coil 3 by the power supply device 5 to generate an alternating magnetic field, and the catalyst carrier 2 is subjected to high-frequency induction heating to promote activation of the catalyst at a low temperature. That is, when a high-frequency current is applied to the induction coil 3 to generate an alternating magnetic field, eddy current loss and hysteresis loss (however, the hysteresis loss can be neglected because the hysteresis loss is extremely small) occur in the catalyst carrier 2 made of a magnetic material. . As a result, mainly the eddy current is converted into Joule heat by the internal resistance of the material forming the catalyst carrier 2, and the catalyst carrier 2 is heated.
[0015]
In this case, as the catalyst carrier 2 made of a magnetic material, an iron-based material having a relatively large skin resistance is used (however, some stainless steels have a relatively small electric resistance, so that they can be used for induction heating. The heating depth is controlled by appropriately setting the frequency of the high-frequency current supplied to the induction coil 3 so that the vicinity of the surface of the catalyst carrier 2 is heated.
[0016]
As shown in FIG. 1, the power supply device 5 is connected in series to a DC-DC converter 7 as a charging unit, an electric double layer capacitor 8, a DC-AC inverter 9 as a high-frequency current applying unit, and the induction coil 3. The apparatus includes a resonance capacitor 10 and a heating power supply control circuit unit 11 as catalyst heating control means.
[0017]
The DC-DC converter 7 boosts the DC voltage of the battery 6 and charges the electric double layer capacitor 8, and the DC-AC inverter 9 is charged by the DC-DC converter 7. A DC voltage from the electric double layer capacitor 8 is converted into an AC voltage, and a high-frequency current is supplied to the induction coil 3 via the resonance capacitor 10.
[0018]
That is, since the induction coil 3 can be converted into an equivalent coil L0 and an equivalent resistance R0 in a circuit, an RLC series circuit is formed by connecting the resonance capacitor 10 to the induction coil 3 so that a high frequency at a resonance frequency is obtained. Induction heating is performed, and by increasing the voltage from the battery 6 and charging the electric double-layer capacitor 8, large power can be supplied in a short time. The current value can be reduced by energizing the induction coil 3 to reduce the load on the battery 6, thereby improving the durability, and avoiding an increase in the size and weight associated with the increase, and a power loss. Can be reduced.
[0019]
The heating and power supply control circuit 11 controls the operation / stop of the DC-AC inverter 9 according to the catalyst temperature. As will be described later, when the catalyst temperature is lower than a reference temperature, the DC-AC inverter 9 is turned off. By operating the AC inverter 9 and stopping the DC-AC inverter 9 when the catalyst temperature is higher than the reference temperature, the deviation of the resonance frequency caused by the temperature change of the equivalent resistance R0 of the induction coil 3 is corrected, Prevents a decrease in heating efficiency.
[0020]
Specifically, the heating and power supply control circuit unit 11 mainly includes a comparator 12 and an AND gate 13, and the comparator 12 is connected to a constant voltage (+ in FIG. The reference voltage generated by the voltage dividing resistors R1 and R2 that divide the constant voltage is applied to the inverting input side via the resistor R3, and the constant voltage is divided by the resistor R4 and the temperature sensor (sensor resistor) 4. Is applied to the non-inverting input side via the resistor R5.
[0021]
An output side of the comparator 12 is connected to one input side of the AND gate 13, and a control command voltage for instructing start of heating of the catalyst carrier 2 is input to the other input side of the AND gate 13. The output side of the AND gate 13 is connected to the DC-AC inverter 9.
[0022]
In the power supply device 5 having the above configuration, for example, when the catalyst temperature is low in the cold state of the engine such as when the engine is started and the like, the control command voltage for instructing the start of the heating of the catalyst is input to the power supply device 5 and the DC-DC converter 7 The DC voltage of the electric double layer capacitor 8 that has been charged by boosting the DC voltage of the battery 6 is converted into a high-frequency voltage by the DC-AC inverter 9, a high-frequency current is supplied to the induction coil 3, and the catalyst carrier 2 is heated by induction. Is done.
[0023]
That is, as shown in FIG. 2, when a high-level control command voltage for instructing the start of heating of the catalyst is input to the AND gate 13 of the heating and power supply control circuit 11, the sensor temperature (catalyst temperature) of the temperature sensor 4 is used as a reference. When the temperature is lower than the temperature, the resistance of the temperature sensor 4 is large, so that the comparison voltage applied to the non-inverting input side of the comparator 12 becomes higher than the reference voltage on the inverting input side. As a result, a high-level signal is output from the comparator 12, and the DC-AC inverter 9 is operated by the high-level heating power supply permission signal from the AND gate 13.
[0024]
Next, when the catalyst temperature rises and becomes higher than the reference temperature, the resistance of the temperature sensor 4 decreases, and the comparison voltage applied to the non-inverting input side of the comparator 12 becomes lower than the reference voltage on the inverting input side. Then, the output voltage of the comparator 12 is inverted to low level, the output voltage of the AND gate 13 becomes low level, and the DC-AC inverter 9 stops.
[0025]
As described above, while the high-level control command voltage is being input, the output of the comparator 12 is inverted between the high level and the low level according to the signal from the temperature sensor 4, so that the output from the AND gate 13 is obtained. As a result, the DC-AC inverter 9 repeats the operation and stop, and the resonance frequency is prevented from being shifted due to the temperature change of the equivalent resistance R0 of the induction coil 3 due to the heating of the catalyst carrier 2, and the heating power is efficiently supplied.
[0026]
Then, when a predetermined time has elapsed after the start of catalyst heating and the catalyst has been sufficiently activated, when the control command voltage is set to low level to instruct the end of heating, the output of the AND gate 13 becomes low level, The DC-AC inverter 9 stops and the heating ends.
[0027]
【The invention's effect】
As described above, according to the present invention, by increasing the voltage from the battery and charging the electric double-layer capacitor, a large amount of power can be supplied in a short time at the start of energizing the induction coil. The high-voltage DC voltage is converted to a high frequency, and a high-frequency current at a resonance frequency is supplied to the induction coil through a resonance capacitor to reduce the current value. In order to correct the deviation of the resonance frequency of the induction coil by controlling the energization, the power from the battery can be efficiently supplied to the catalyst carrier as the heating power, thereby reducing the load on the battery and improving the durability, In addition, excellent effects can be obtained, such as an increase in size and the accompanying increase in weight and reduction in power loss.
[Brief description of the drawings]
FIG. 1 is a circuit connection diagram of a power supply device. FIG. 2 is a waveform diagram showing a control operation. FIG. 3 is a schematic sectional view of a catalytic converter.
2 Catalyst carrier 3 Induction coil 6 Battery 7 DC-DC converter (charging means)
8 Electric double layer capacitor 9 DC-AC converter (high frequency current supply means)
10 Resonance capacitor 11 Heating and power supply control circuit (catalyst heating control means)

Claims (1)

In a power supply device for heating a catalyst for high-frequency induction heating of a catalyst carrier having a catalyst component supported on its surface,
Charging means for boosting the voltage of the battery and charging the electric double layer capacitor;
The DC voltage from the electric double layer capacitor charged by the charging means is converted into an AC voltage , and the induction coil wound around the outer periphery of the catalyst carrier is subjected to resonance via a resonance capacitor connected in series to the induction coil. a high-frequency current supply means for applying a high frequency current at a frequency,
A catalyst heating control unit that corrects a deviation of the resonance frequency of the induction coil by controlling the operation / stop of the high-frequency current supply unit in accordance with the catalyst temperature; .

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