JP6314804B2 - Electronic control unit - Google Patents

Description

  The present invention relates to an electronic control unit that controls a reactor that generates discharge.

  2. Description of the Related Art Conventionally, a technique for purifying exhaust gas discharged from an automobile engine by applying a voltage to a reactor to generate discharge is known (see, for example, Patent Document 1).

JP-A-2005-337200

  However, in a high temperature environment or a high humidity environment, the amount of ozone generated by discharge decreases. Therefore, it is necessary to adjust the driving method of the reactor so that the amount of generated ozone does not decrease according to the temperature and humidity in the environment where the reactor is installed. For this reason, there is a problem in that both a temperature sensor that detects the temperature of the environment in which the reactor is installed (hereinafter referred to as the reactor installation environment) and a humidity sensor that detects the humidity of the reactor installation environment must be installed separately. there were.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a technique that enables a reactor to be controlled without installing any one of a temperature sensor and a humidity sensor.

  The present invention made to achieve the above object is an electronic control device for controlling a reactor that generates a discharge between a first electrode and a second electrode, comprising a resonance frequency acquisition means, an atmosphere information acquisition means, And an estimation means.

The resonance frequency acquisition means acquires resonance frequency information indicating the resonance frequency of the LC resonance generated in the reactor after the discharge.
The atmosphere information acquisition means acquires any one of atmosphere temperature information indicating the atmosphere temperature that is the temperature in the gas atmosphere in which the reactor is installed and atmosphere humidity information indicating the atmosphere humidity that is the humidity in the gas atmosphere. .

  When the atmosphere information acquisition unit acquires the atmosphere temperature information, the estimation unit estimates the atmospheric humidity based on the atmosphere temperature indicated by the atmosphere temperature information and the resonance frequency indicated by the resonance frequency information. In addition, when the atmosphere information acquisition unit acquires the atmospheric humidity information, the estimation unit estimates the atmospheric temperature based on the atmospheric humidity indicated by the atmospheric humidity information and the resonance frequency indicated by the resonance frequency information.

  The electronic control device of the present invention configured as described above can estimate the atmospheric humidity when the atmospheric information acquisition unit acquires the atmospheric temperature information, and therefore does not require a sensor for detecting the atmospheric humidity. can do.

  Further, the electronic control device of the present invention can estimate the atmospheric temperature when the atmospheric information acquisition means acquires the atmospheric humidity information, so that a sensor for detecting the atmospheric temperature can be dispensed with. .

  As described above, the electronic control device of the present invention provides a reactor without installing any one of the sensor for detecting the temperature in the gas atmosphere and the sensor for detecting the humidity in the gas atmosphere in the gas atmosphere. Can be controlled.

1 is a diagram illustrating a configuration of an exhaust purification system 1. FIG. It is a flowchart which shows a drive process. It is a flowchart which shows a duty change process. It is a timing chart which shows a reactor application voltage, a drive signal, and a frequency voltage.

Embodiments of the present invention will be described below with reference to the drawings.
The exhaust purification system 1 of this embodiment is mounted on a vehicle and includes an electronic control unit (Electronic Control Unit) 2 (hereinafter referred to as ECU 2), a reactor 3, a drive circuit 4, and a temperature sensor 5, as shown in FIG. .

The ECU 2 includes a microcomputer (hereinafter referred to as a microcomputer) 11, a drive signal output unit 12, a frequency-voltage conversion unit 13, and an AD converter 14.
The microcomputer 11 includes a CPU 21, a ROM 22, a RAM 23, an input / output port 24, a communication circuit 25, and a bus line 26 that connects these components to each other.

The CPU 21 executes various processes for controlling the reactor 3 based on the program stored in the ROM 22.
The ROM 22 is a nonvolatile memory, and stores a program executed by the CPU 21 and data referred to when the program is executed.

The RAM 23 is a volatile memory, and temporarily stores calculation results of the CPU 21 and the like.
The input / output port 24 is a circuit for inputting / outputting signals between the outside of the microcomputer 11 and the microcomputer 11.

  The communication circuit 25 performs data communication with various devices mounted on the vehicle via an in-vehicle LAN (Local Area Network) 110. The in-vehicle LAN 110 is connected to an engine ECU 120 that controls the engine of the vehicle. Thereby, ECU2 is connected to engine ECU120 so that data communication is possible.

The reactor 3 is installed inside a pipe 140 that introduces air into an exhaust pipe 130 that forms a passage for exhausting the exhaust discharged from the engine to the outside of the vehicle.
The reactor 3 includes electrodes 31 and 32. When a high voltage is applied between the electrode 31 and the electrode 32, discharge is generated in the space between the electrode 31 and the electrode 32, and ozone is generated. The ozone generated in the reactor 3 is supplied into the exhaust pipe 130 through the pipe 140 and purifies the exhaust gas in the exhaust pipe 130.

The drive circuit 4 includes a transistor 41, a diode 42, a transformer 43, and a DC power supply 44.
The transistor 41 is an NPN transistor and has an emitter, a base, and a collector. The emitter is connected to the negative electrode of the DC power supply 44. The collector is connected to the positive electrode of the DC power supply 44 through the transformer 43. The base is connected to the drive signal output unit 12 of the ECU 2.

The diode 42 has an anode connected to the emitter of the transistor 41 and a cathode connected to the collector of the transistor 41.
The transformer 43 includes a primary coil 51 and a secondary coil 52. The primary coil 51 has one end connected to the positive electrode of the DC power supply 44 and the other end connected to the collector of the transistor 41. The secondary coil 52 has one end connected to the electrode 31 of the reactor 3 and the other end connected to the negative electrode of the DC power supply 44.

The electrode 32 of the reactor 3 is connected to the negative electrode of the DC power supply 44.
The temperature sensor 5 is installed inside the pipe 140, detects the temperature of the air in the pipe 140, and outputs the detection result to the microcomputer 11.

  The drive signal output unit 12 outputs a drive signal for driving the transistor 41 to the drive circuit 4 based on a pulse-on command (described later) and a pulse-off command (described later) output from the microcomputer 11.

  A voltage between the electrode 31 and the electrode 32 of the reactor 3 is input to the frequency-voltage converter 13. The frequency-voltage converter 13 detects the frequency of the input voltage, and outputs the frequency voltage converted to a voltage corresponding to the detected frequency to the AD converter 14.

The AD converter 14 converts the input frequency voltage into a digital signal and outputs the digital signal to the microcomputer 11.
In the ECU 2 configured as described above, the CPU 21 of the microcomputer 11 executes a drive process and a duty change process.

First, the procedure of the driving process will be described. This driving process is started immediately after the microcomputer 11 is activated.
When this drive process is executed, the CPU 21 first sets the drive frequency Fd and the duty Dd to initial values in S10 as shown in FIG.

  In S20, the drive start determination timer provided in the RAM 23 is incremented. The drive start determination timer automatically increments (adds 1) every 1 ms, for example, and when reset at a certain time, it increments from 0 again at that time.

Thereafter, in S30, the drive cycle Td is calculated based on the drive frequency Fd, and the pulse-on time Ton is calculated based on the drive cycle Td and the duty Dd.
In S40, it is determined whether or not the driving cycle Td has elapsed. Specifically, when the value of the drive start determination timer is equal to or greater than the value corresponding to the drive cycle Td, it is determined that the drive cycle Td has elapsed.

  Here, when the drive cycle Td has not elapsed (S40: NO), the process of S40 is repeated to wait until the drive cycle Td has elapsed. When the drive cycle Td has elapsed (S40: YES), the drive start determination timer is reset in S50. In S60, the pulse-on determination timer provided in the RAM 23 is incremented. The pulse-on determination timer is a timer that automatically increments every 1 ms, for example. When the increment is started, the value is incremented from 0.

  In step S70, a pulse-on command is output to the drive signal output unit 12. As a result, the drive signal output unit 12 starts outputting a drive signal that turns on the transistor 41. When the transistor 41 is turned on, a current flows through the primary coil 51 of the transformer 43.

  In S80, it is determined whether or not the pulse-on time Ton has elapsed. Specifically, when the value of the pulse on determination timer is equal to or greater than the value corresponding to the pulse on time Ton, it is determined that the pulse on time Ton has elapsed.

  Here, when the pulse-on time Ton has not elapsed (S80: NO), the process of S80 is repeated to wait until the pulse-on time Ton has elapsed. When the pulse-on time Ton elapses (S80: YES), the increment of the pulse-on determination timer is stopped in S90.

  Next, in S100, a pulse-off command is output to the drive signal output unit 12. When the pulse-off command is input to the drive signal output unit 12, the drive signal output unit 12 stops outputting the drive signal. When the output of the drive signal is stopped, the transistor 41 is turned off. Thereby, the energization to the primary coil 51 of the transformer 43 is cut off, and a high voltage is generated in the secondary coil 52.

  Thereafter, in S110, it is determined whether the Nox concentration indicated by the Nox concentration information received from engine ECU 120 exceeds a preset Nox reference value. Here, when the Nox concentration is equal to or less than the Nox reference value (S110: NO), the process proceeds to S130.

  On the other hand, when the Nox concentration exceeds the Nox reference value (S110: YES), in S120, only the drive frequency increase value in which the drive frequency Fd is set in advance (a value corresponding to 1 kHz in the present embodiment). Increase it and go to S130.

  When the process proceeds to S130, it is determined whether the Nox concentration indicated by the Nox concentration information received from the engine ECU 120 is less than the Nox reference value. If the Nox concentration is greater than or equal to the Nox reference value (S130: NO), the process proceeds to S30.

  On the other hand, when the Nox concentration is less than the Nox reference value (S130: YES), in S140, the drive frequency Fd is decreased by a preset drive frequency decrease value (a value corresponding to 1 kHz in the present embodiment). Then, the process proceeds to S30.

Next, the procedure of duty change processing will be described. This duty change process is started immediately after the microcomputer 11 is activated.
When the duty changing process is executed, the CPU 21 first starts incrementing an estimation permission determination timer provided in the RAM 23 in S210 as shown in FIG. The estimation permission determination timer is automatically incremented every 1 ms, for example, and when reset at a certain time, it is incremented from 0 again at that time.

  Then, in S220, it is determined whether or not the estimated permission period Tp has elapsed. Specifically, when the value of the estimation permission determination timer is equal to or greater than a value corresponding to a preset estimation permission period Tp, it is determined that the estimation permission period Tp has elapsed. Note that the estimation permission period Tp is set to be sufficiently longer than the driving period Td (for example, about 10 times the driving period Td).

  Here, when the estimation permission period Tp has not elapsed (S220: NO), the process of S220 is repeated to wait until the estimation permission period Tp has elapsed. When the estimation permission period Tp has elapsed (S220: YES), the estimation permission determination timer is reset in S230.

  Next, in S240, it is determined whether or not the drive frequency Fd is less than a preset estimated prohibition frequency Fp. Here, when the drive frequency Fd is equal to or higher than the estimated prohibition frequency Fp (S240: NO), the process proceeds to S220. On the other hand, if the drive frequency Fd is less than the estimated prohibition frequency Fp (S240: YES), it is determined in S250 whether or not a pulse-off command is output from the microcomputer 11.

  Here, when the pulse-off command is not output (S250: NO), the process of S250 is repeated to wait until the pulse-off command is output. When the pulse-off command is output (S250: YES), the estimation start determination timer provided in the RAM 23 is incremented in S260. The estimation start determination timer is a timer that automatically increments every 1 ms, for example. When the increment is started, the value is incremented from 0.

  Thereafter, in S270, it is determined whether or not the start determination time Ts has elapsed. Specifically, when the value of the estimation start determination timer is equal to or greater than the value corresponding to the start determination time Ts, it is determined that the start determination time Ts has elapsed. The start determination time Ts is set to be longer than the conversion result unstable period Ti. The conversion result unstable period Ti is a period during which the conversion result by the frequency-voltage conversion unit 13 becomes unstable (see FIG. 4), and is a constant uniquely determined based on circuit constants.

  If the start determination time Ts has not elapsed (S270: NO), the process of S270 is repeated to wait until the start determination time Ts elapses. Then, when the start determination time Ts elapses (S270: YES), the estimation start determination timer increment is stopped in S280.

  Next, in S290, the temperature detection table in which the correspondence between the detection result of the temperature sensor 5 and the temperature of the air in the pipe 140 is set in advance is referred to, and the temperature Ta of the air in the pipe 140 is specified. .

  In S300, the digital signal of the frequency voltage is acquired from the AD converter 14, and the resonance frequency f is specified by referring to the frequency detection table in which the correspondence relationship between the frequency voltage and the resonance frequency f is set in advance. .

In S310, the inductance of the secondary coil 52 of the transformer 43 is set to L, and the capacity C of the reactor 3 is calculated by the following equation (1).
C = 1 / (4 × π ² × f ² × L) (1)
Further, in S320, the correspondence between the temperature Ta and the capacity C and the humidity Ha of the air in the pipe 140 is calculated with reference to the preset humidity detection map, and the temperature Ta and S310 specified in S290 are calculated. Based on the capacity C, the humidity Ha of the air in the pipe 140 is specified. The capacitance C depends on the dielectric constant of the air between the electrode 31 and the electrode 32, and the dielectric constant of the air varies with temperature and humidity. For this reason, the humidity Ha can be specified based on the capacitance C and the temperature Ta.

  Thereafter, in S330, by referring to the duty setting map in which the correspondence between the temperature Ta and humidity Ha and the duty is set in advance, based on the temperature Ta specified in S290 and the humidity Ha specified in S320, Specify the duty.

In S340, the duty Dd is set to the value of the duty specified in S330, and the process proceeds to S220.
Next, the procedure for operating the reactor 3 in the exhaust purification system 1 configured as described above and the timing for setting the duty Dd will be described.

  As shown in FIG. 4, first, output of the drive signal is started (see time t01), and output of the drive signal is stopped after the pulse-on time Ton has elapsed from the start of output of the drive signal (see time t02). . As a result, a high voltage is generated in the secondary coil 52, and this high voltage is applied to the reactor 3 (refer to the reactor applied voltage from time t02 to time t03, t04). By applying this high voltage, a discharge is generated between the electrode 31 and the electrode 32 of the reactor 3, and ozone is generated.

  After the discharge is completed, the reactor 3 operates as a capacitor, and LC resonance having a resonance frequency determined by the capacitance C of the reactor 3 and the inductance L of the secondary coil 52 of the transformer 43 occurs (time t03, t04 to t04). (See the reactor applied voltage at time t08).

  For this reason, the frequency of the voltage applied to the reactor 3 at the time of discharge (refer to the frequency voltage from time t02 to time t03) is the frequency of the voltage applied to the reactor 3 after the end of discharge (frequency from time t03, t04 to time t08). Voltage (see voltage). In FIG. 4, the solid line L1 indicating the reactor applied voltage during the period from time t03 to time t08 indicates that the frequency is higher than the broken line L2 indicating the reactor applied voltage during the period from time t04 to time t08. . In FIG. 4, a solid line L3 indicating the frequency voltage during the period from time t03 to time t08 indicates a voltage corresponding to the solid line L1, and a broken line L4 indicating the frequency voltage during the period from time t04 to time t08 is a broken line. The voltage corresponding to L2 is shown.

  Then, when the start determination time Ts elapses after the drive signal output is stopped (see time t02) (see time t06), the process of setting the duty Dd based on the temperature Ta and the capacity C is started. The start determination time Ts is set to be longer than the conversion result unstable period Ti (see the period from time t02 to time t05).

  Further, after the drive cycle Td has elapsed from the start of output of the drive signal (see time t01), the output of the next drive signal is started (see time t07), and the pulse-on time Ton has elapsed from the start of output of the drive signal. After that, output of the drive signal is stopped (see time t08).

The ECU 2 configured as described above controls the reactor 3 that generates discharge between the electrode 31 and the electrode 32.
The ECU 2 acquires information indicating the resonance frequency f of the LC resonance generated in the reactor 3 after the discharge (S300). Further, the ECU 2 acquires information indicating the temperature Ta of the air in the pipe 140 where the reactor 3 is installed (S290).

Then, the ECU 2 estimates the humidity Ha of the air in the pipe 140 based on the resonance frequency f and the temperature Ta (S310, S320).
As described above, the ECU 2 can estimate the humidity Ha of the air in the pipe 140, so that a sensor for detecting the humidity of the air in the pipe 140 can be omitted. Therefore, the ECU 2 can control the reactor 3 without installing a sensor for detecting the humidity of the air in the pipe 140 in the pipe 140.

  Further, the ECU 2 estimates the humidity Ha every time the estimated permission period Tp set so as to be longer than the driving period Td in which the reactor 3 generates discharge is passed. Thus, the ECU 2 may not perform the process of estimating the humidity Ha every time the reactor 3 generates a discharge (that is, every time LC resonance occurs), but may thin out the process of estimating the humidity Ha. And the processing load on the microcomputer 11 can be reduced. Note that the temperature Ta and the humidity Ha do not change greatly in the driving cycle Td, and therefore, it is not necessary to execute the process of estimating the humidity Ha for each driving cycle Td.

  Further, the ECU 2 prohibits the estimation of the humidity Ha when the driving frequency Fd at which the reactor generates discharge is equal to or higher than a preset estimation prohibition frequency Fp (S240). As a result, the ECU 2 continues until the time necessary for detecting the resonance frequency f (that is, the time required for the frequency-voltage converter 13 to output the frequency voltage corresponding to the resonance frequency f) elapses. The occurrence of a situation where the drive signal is output can be suppressed. If the next drive signal is output before the time necessary for detecting the resonance frequency f elapses, the frequency voltage output by the frequency-voltage converter 13 reflects the actual resonance frequency f. As a result, the estimation accuracy of the humidity Ha decreases.

  In the embodiment described above, the ECU 2 is the electronic control device according to the present invention, the processing at S300 is the resonance frequency acquisition means according to the present invention, the processing at S290 is the atmosphere information acquisition means according to the present invention, and the processing at S310 and S320 is the estimation according to the present invention. Means.

  Further, the driving cycle Td is the discharge generation cycle in the present invention, the estimation permission cycle Tp is the estimation cycle in the present invention, the processing of S240 is the prohibition means in the present invention, the drive frequency Fd is the discharge frequency in the present invention, and the estimated prohibition frequency Fp is the present It is a forbidden frequency in the invention.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, As long as it belongs to the technical scope of this invention, a various form can be taken.
For example, in the above embodiment, the humidity Ha is estimated by installing the temperature sensor 5 inside the pipe 140. However, instead of the temperature sensor 5, the humidity sensor is installed inside the pipe 140, so that the pipe The temperature Ta of the air in 140 may be estimated.

By installing a humidity sensor, the processing of S290, S320, and S330 is changed as described below.
First, in S290, the humidity Ha of the air in the pipe 140 is specified with reference to a humidity detection table in which the correspondence between the detection result of the humidity sensor and the humidity of the air in the pipe 140 is set in advance.

  In S320, the humidity Ha and the capacity calculated in S310 specified in S290 are referred to by referring to a temperature detection map in which the correspondence between the humidity Ha and the capacity C and the temperature Ta of the air in the pipe 140 is set in advance. Based on C, the temperature Ta of the air in the pipe 140 is specified.

  In S330, by referring to the duty setting map in which the correspondence between the temperature Ta and the humidity Ha and the duty is set in advance, the duty is determined based on the humidity Ha specified in S290 and the temperature Ta specified in S320. Is identified.

  Moreover, in the said embodiment, what showed the timing which starts the process which estimates the humidity Ha based on the time after a pulse-off instruction | command was output was shown, However, based on the time after a pulse-on instruction | command was output It may be determined.

  In addition, the functions of one component in the above embodiment may be distributed as a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

  DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification system, 2 ... ECU, 3 ... Reactor, 4 ... Drive circuit, 5 ... Temperature sensor, 11 ... Microcomputer, 12 ... Drive signal output part, 13 ... Frequency-voltage conversion part, 21 ... CPU, 31 ... Electrode 32 ... Electrodes

Claims (3)

An electronic control device (2) for controlling a reactor (3) that generates a discharge between a first electrode (31) and a second electrode (32),
Resonance frequency acquisition means (S300) for acquiring resonance frequency information indicating a resonance frequency of LC resonance generated in the reactor after the discharge;
Atmosphere information acquisition means for acquiring any one of atmosphere temperature information indicating an atmosphere temperature that is a temperature in a gas atmosphere in which the reactor is installed and atmosphere humidity information indicating an atmosphere humidity that is a humidity in the gas atmosphere (S290),
When the atmosphere information acquisition means acquires the atmosphere temperature information, the atmosphere humidity is estimated based on the atmosphere temperature indicated by the atmosphere temperature information and the resonance frequency indicated by the resonance frequency information, and When the atmosphere information acquisition means acquires the atmosphere humidity information, the estimation means for estimating the atmosphere temperature based on the atmosphere humidity indicated by the atmosphere humidity information and the resonance frequency indicated by the resonance frequency information ( S310, S320). An electronic control device comprising: The estimation means includes
2. The electron according to claim 1, wherein the atmospheric humidity or the atmospheric temperature is estimated each time an estimated period set so as to be longer than a discharge generation period in which the reactor generates the discharge. Control device. When the discharge frequency at which the reactor generates the discharge is equal to or higher than a preset prohibition frequency, the reactor includes a prohibition unit (S240) for prohibiting the estimation unit from estimating the atmospheric humidity or the ambient temperature. The electronic control device according to claim 1 or 2.

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