Exhaust purifier
By utilizing a primary current sensor and control circuit to detect and adjust secondary voltage based on primary current values, the device effectively addresses the challenge of PM removal in exhaust gas purification devices, reducing costs and improving efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DAIHATSU MOTOR CO LTD
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-30
Smart Images
Figure 2026106765000001_ABST
Abstract
Description
Technical Field
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[0001] The present invention relates to an exhaust gas purification device.
Background Art
[0002] As an invention related to a conventional exhaust gas purification device, for example, a plasma reactor device for exhaust gas purification described in Patent Document 1 is known. This plasma reactor device for exhaust gas purification purifies exhaust gas using plasma. This plasma reactor device for exhaust gas purification detects the presence or absence of PM deposition on the reactor using a negative current integrated value.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
[0007] The second aspect is, The exhaust gas purification device further comprises an inverting circuit and a peak hold circuit. The inverting circuit converts the value of the primary current detected by the current sensor into the absolute value of the primary current. The peak hold circuit generates the absolute value of the peak hold value based on the absolute value of the primary current. This is the exhaust gas purification device described on the first side.
[0008] The third aspect is, If the peak value of the primary current immediately before the reactor discharges is less than the second reference value, or if the absolute value of the peak hold value of the primary current immediately after the reactor discharges is less than the third reference value, the control circuit shall not increase the secondary voltage of the power supply circuit. This is an exhaust gas purification device as described on the first or second side.
[0009] The fourth aspect is, As the peak value of the primary current immediately before the reactor discharges increases, the first reference value increases. This is an exhaust gas purification device as described in any of the first, second, or third sides.
[0010] The fifth aspect is, If the absolute value of the peak hold value of the primary current detected by the current sensor is smaller than the first reference value, PM is deposited on the reactor, and the control circuit increases the secondary voltage of the power supply circuit. This is an exhaust gas purification device as described in any of the first to fourth sides.
[0011] The sixth side is The exhaust gas purification device includes a power source, a power source circuit, a reactor, a current sensor, and a control circuit. The power source circuit generates a secondary voltage by boosting the primary voltage generated by the power source. The reactor generates plasma by the secondary voltage generated by the power source circuit and purifies the exhaust gas of the internal combustion engine. The current sensor detects the primary current generated together with the primary voltage in the power source circuit. When the absolute value of the peak hold value of the primary current detected by the current sensor is smaller than the first reference value, the control circuit determines that PM is deposited on the reactor. It is an exhaust gas purification device.
Advantages of the Invention
[0012] According to the present invention, PM deposited on the reactor can be removed.
Brief Description of the Drawings
[0013] [Figure 1] FIG. 1 is a schematic diagram of the vehicle 10. [Figure 2] FIG. 2 is a circuit diagram of the power source circuit 13. [Figure 3] FIG. 3 is a graph showing the relationship between the value of the primary current I1 and time. [Figure 4] FIG. 4 is a graph showing the relationship between the absolute value I11 of the primary current I_{1} and time. [Figure 5] FIG. 5 is a graph showing the relationship between the peak hold value P2 output by the peak hold circuit 16 and time. [Figure 6] FIG. 6 is a graph showing the relationship between the peak value P1 and the peak hold value P2. [Figure 7] FIG. 7 is a flowchart executed by the control circuit 17.
Embodiments for Carrying Out the Invention
[0014] (Embodiment) [Vehicle structure] The structure of a vehicle 10 equipped with an exhaust gas purification device 11 according to one embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram of the vehicle 10. Figure 2 is a circuit diagram of the power supply circuit 13. Figure 3 is a graph showing the relationship between the value of the primary current I1 and time. Figure 4 is a graph showing the relationship between the absolute value I11 of the primary current I1 and time. Figure 5 is a graph showing the relationship between the peak hold value P2 output by the peak hold circuit 16 and time.
[0015] Vehicle 10 is driven by power generated by an internal combustion engine 20. Vehicle 10 is, for example, a four-wheeled automobile. As shown in Figure 1, vehicle 10 is equipped with an exhaust purification device 11 and an internal combustion engine 20.
[0016] The internal combustion engine 20 is used as a power source for an automobile. The internal combustion engine 20 is, for example, a four-stroke engine that uses gasoline as fuel. The structure of the internal combustion engine 20 is a common one, so a detailed explanation is omitted.
[0017] The internal combustion engine 20 is connected to an intake path R1 and an exhaust path R2. The intake path R1 is the path through which air passes. The exhaust path R2 is the path through which exhaust gases pass.
[0018] The exhaust gas purification device 11 is used in the internal combustion engine 20 of the vehicle 10. The exhaust gas purification device 11 reduces the particulate matter (PN) by removing particulate matter (PM) from the exhaust gas. As shown in Figure 1, the exhaust gas purification device 11 includes a power supply 12, a power supply circuit 13, a current sensor 14, an inverting circuit 15, a peak hold circuit 16, a control circuit 17, and a reactor 18.
[0019] Power source 12 is a battery that generates a DC voltage with a primary voltage V1 (12V). Power source 12 is, for example, a lead-acid battery.
[0020] The power supply circuit 13 generates a secondary voltage V2 by boosting the primary voltage V1 generated by the power supply 12. The power supply circuit 13 has a primary circuit 13a and a secondary circuit 13b. As shown in Figure 2, the power supply circuit 13 includes a transformer 130, a switch 131, and a diode 132. The power supply 12, the primary coil of the transformer 130, the switch 131, and the current sensor 14 (described later) are connected in series in the primary circuit 13a. The secondary coil of the transformer 130, the diode 132, and the reactor 18 (described later) are connected in series in the secondary circuit 13b. When the switch 131 is turned on or off, the transformer 130 boosts the primary voltage V1 generated by the power supply 12 to generate a secondary voltage V2. The diode 132 smooths the secondary voltage V2. The secondary voltage V2 is then applied to the reactor 18.
[0021] The reactor 18 is located in the exhaust path R2. The reactor 18 generates plasma using the secondary voltage V2 generated by the power supply circuit 13 to purify the exhaust gas from the internal combustion engine 20. The reactor 18 has multiple electrodes. The multiple electrodes are stacked in an insulated state from each other. An AC voltage generated by the power supply circuit 13 is applied to the multiple electrodes. This causes a discharge to occur between two adjacent electrodes. As a result, plasma is generated between two adjacent electrodes. The plasma decomposes PM contained in the exhaust gas.
[0022] The current sensor 14 is provided in the primary circuit 13a. The current sensor 14 detects the primary current I1 that is generated together with the primary voltage V1 in the power supply circuit 13.
[0023] The inverting circuit 15 converts the value of the primary current I1 detected by the current sensor 14 into its absolute value I11. More specifically, in the graph in Figure 3, the reactor 18 discharges at 21 ms. As shown in Figure 3, the value of the primary current I1 has a peak just before the reactor 18 discharges. After the reactor 18 discharges, the value of the primary current I1 alternates between positive and negative values. Therefore, the inverting circuit 15 converts the value of the primary current I1 into its absolute value I11, as shown in the graph in Figure 4. The absolute value I11 is then converted into a voltage value.
[0024] The peak hold circuit 16 generates the absolute value of the peak hold value (hereinafter simply referred to as the peak hold value P2) based on the absolute value I11 of the primary current I1. More specifically, the peak hold circuit 16 outputs the peak value P2 of the absolute value I11 of the primary current I1 after the reactor 18 has discharged. In Figure 5, the peak hold circuit 16 outputs the peak value P2 of the peak value P2 of the absolute value I11 of the primary current I1 at 27ms.
[0025] Although not shown in the diagram, the peak hold circuit 16 outputs the peak value P1 of the absolute value I11 of the primary current I1 immediately before the reactor 18 discharges. In this embodiment, the peak hold circuit 16 outputs the peak value P1 of the absolute value I11 of the primary current I1 at 21ms. The peak hold circuit 16 is, for example, an operational amplifier.
[0026] The control circuit 17 is an ECU (Electric Control Unit). The control circuit 17 is a combination of a circuit board, semiconductor device, and electronic components. If the peak hold value P2 of the primary current I1 detected by the current sensor 14 is smaller than the first reference value A1, the control circuit 17 determines that PM has accumulated on the reactor 18. In this case, the control circuit 17 increases the secondary voltage V2 in the power supply circuit 13. This removes the PM accumulated on the reactor 18.
[0027] [Operation of the exhaust purification system] Next, the operation of the exhaust gas purification device 11 will be explained. Figure 6 is a graph showing the relationship between the peak value P1 and the peak hold value P2. Figure 7 is a flowchart of the actions performed by the control circuit 17.
[0028] As shown in Figure 4, when PM accumulates on the reactor 18, the absolute value I11 of the primary current I1 decreases. Therefore, the control circuit 17 can determine whether or not PM is accumulating on the reactor 18 based on the absolute value I11 of the primary current I1. However, the absolute value I11 of the primary current I1 changes over time. Therefore, the control circuit 17 determines whether or not PM is accumulating on the reactor 18 by determining whether or not the peak hold value P2 is smaller than the first reference value A1.
[0029] However, as the peak value P1 increases, the peak hold value P2 also increases. Therefore, the first reference value A1 needs to be changed according to the peak value P1. Accordingly, the memory circuit included in the control circuit 17 stores information (table) corresponding to the graph in Figure 6. In the graph in Figure 6, a straight line L1 is depicted. The straight line L1 shows a monotonically increasing trend in the region where the peak value P1 is greater than the second reference value A2, and in the region where the peak hold value P2 is greater than the third reference value A3. The straight line L1 does not exist in the region where the peak value P1 is less than the second reference value A2, and in the region where the peak hold value P2 is less than the third reference value A3. The straight line L1 shows the relationship between the peak value P1 and the first reference value A1. As the peak value P1 increases, the first reference value A1 increases. Therefore, PM accumulates in the reactor 18 in the region below the straight line L1. In the region above the straight line L1, no PM accumulates in the reactor 18. In this embodiment, no PM is deposited on the reactor 18 in the straight line L1.
[0030] When this process begins, the control circuit 17 sets N to 1 (step S1). N is an integer.
[0031] Next, the control circuit 17 obtains the peak value P1 from the peak hold circuit 16 (step S2). Furthermore, the control circuit 17 obtains the peak hold value P2 from the peak hold circuit 16 (step S3).
[0032] Next, the control circuit 17 determines whether the peak value P1 is greater than or equal to the second reference value A2, and whether the peak hold value P2 is greater than or equal to the third reference value A3 (step S4). In step S4, the control circuit 17 determines whether the peak value P1 and the peak hold value P2 have sufficient values. If the peak value P1 and the peak hold value P2 do not have sufficient values, there is a possibility that an abnormality has occurred in the power supply 12 or the power supply circuit 13, etc. Therefore, if the peak value P1 is greater than or equal to the second reference value A2, and the peak hold value P2 is greater than or equal to the third reference value A3, the control circuit 17 determines that the power supply 12 or the power supply circuit 13, etc. are normal. In this case, the process proceeds to step S6. If the peak value P1 is less than the second reference value A2, or if the peak hold value P2 is less than the third reference value A3, the control circuit 17 determines that an abnormality has occurred in the power supply 12 or the power supply circuit 13, etc. In this case, the process returns to step S2. Thus, if the peak value P1 of the primary current I1 immediately before the reactor 18 discharges is less than the second reference value A2, or if the peak hold value P2 of the primary current I1 immediately after the reactor 18 discharges is less than the third reference value A3, the control circuit 17 does not increase the secondary voltage of the power supply circuit 13.
[0033] If the peak value P1 is greater than or equal to the second reference value A2, and the peak hold value P2 is greater than or equal to the third reference value A3, the control circuit 17 determines whether the peak hold value P2 is less than or equal to the first reference value A1 (step S5). In step S5, the control circuit 17 identifies the first reference value A1 corresponding to the peak value P1 acquired in step S2 based on the graph in Figure 6. Then, the control circuit 17 determines whether the peak hold value P2 is less than or equal to the first reference value A1. If the peak hold value P2 is less than or equal to the first reference value A1, the control circuit 17 determines that PM has accumulated on the reactor 18. In this case, the process proceeds to step S6. If the peak hold value P2 is greater than or equal to the first reference value A1, the control circuit 17 determines that no PM has accumulated on the reactor 18. In this case, the process returns to step S2.
[0034] If the peak hold value P2 is less than the first reference value A1, the control circuit 17 increments N by one (step S6). Then, the control circuit 17 determines whether N is equal to M (step S7). M is a natural number, and in this embodiment it is 10. If N is equal to M, the process proceeds to step S8. If N is not equal to M, the process returns to step S2.
[0035] If N is equal to M, the control circuit 17 stops injecting fuel into the internal combustion engine 20 (step S8). That is, the control circuit 17 stops the operation of the injector (not shown) injecting fuel. However, the control circuit 17 rotates the crankshaft of the internal combustion engine 20 by a motor (not shown). This causes air to pass through the exhaust path R2. That is, air passes through the reactor 18.
[0036] Next, the control circuit 17 increases the secondary voltage V2 in the power supply circuit 13 because PM has accumulated on the reactor 18 (step S9). This increases the intensity of the plasma generated in the reactor 18. As a result, the PM accumulated on the reactor 18 is removed.
[0037] Next, the control circuit 17 determines whether or not to terminate this process (step S10). If the process is not terminated, the process returns to step S1.
[0038] [effect] According to the exhaust gas purification device 11, if the peak hold value P2 of the primary current I1 detected by the current sensor 14 is smaller than the first reference value A1, the control circuit 17 increases the secondary voltage V2 in the power supply circuit 13. This increases the intensity of the plasma generated in the reactor 18. As a result, PM accumulated in the reactor 18 is removed.
[0039] The exhaust gas purification device 11 reduces its manufacturing cost. More specifically, in conventional exhaust gas purification devices, the current sensor detected the secondary current I2 in the secondary circuit. However, since the secondary voltage V2 reaches several thousand volts, the secondary current I2 also has a very large value. Therefore, conventionally, the current sensor needed to be able to detect the secondary current I2, which has a very large value. For this reason, it was not possible to use an inexpensive current sensor in conventional exhaust gas purification devices.
[0040] Therefore, in the exhaust gas purification device 11, the current sensor 14 detects the primary current I1 that is generated together with the primary voltage V1 in the power supply circuit 13. Since the primary voltage V1 is several hundred volts, the primary current I1 is smaller than the secondary current I2. Thus, an inexpensive current sensor can be used as the current sensor 14. As a result, the manufacturing cost of the exhaust gas purification device 11 is reduced.
[0041] In the exhaust gas purification device 11, the inverting circuit 15 converts the value of the primary current I1 detected by the current sensor 14 into the absolute value I11 of the primary current I1. Therefore, the value output from the inverting circuit 15 is always a positive value. Consequently, the peak hold value P2 generated by the peak hold circuit 16 is also always a positive value. As a result, the control circuit 17 does not need to determine whether the peak hold value P2 output from the peak hold circuit 16 is positive or negative. In other words, if the peak hold value P2 is a negative value, the control circuit 17 does not need to convert the peak hold value P2 to a positive value. As a result, the control circuit 17 can determine whether PM is accumulating in the reactor 18 by determining whether the peak hold value P2 is smaller than the first reference value A1.
[0042] In the exhaust gas purification device 11, the control circuit 17 does not unnecessarily increase the secondary voltage V2 in the power supply circuit 13. More specifically, if the peak value P1 and the peak hold value P2 do not have sufficient values, there is a possibility that an abnormality has occurred in the power supply 12 or the power supply circuit 13, etc. Therefore, if the peak value P1 is smaller than the second reference value A2, or if the peak hold value P2 is smaller than the third reference value A3, the control circuit 17 determines that an abnormality has occurred in the power supply 12 or the power supply circuit 13, etc. In this case, the control circuit 17 does not increase the secondary voltage V2 in the power supply circuit 13. As a result, in the exhaust gas purification device 11, the control circuit 17 does not unnecessarily increase the secondary voltage V2 in the power supply circuit 13.
[0043] In the exhaust gas purification device 11, the control circuit 17 can appropriately determine whether or not PM is accumulating on the reactor 18. More specifically, as the peak value P1 increases, the peak hold value P2 also increases. Therefore, the first reference value A1 depends on the magnitude of the peak value P1. Accordingly, the memory circuit included in the control circuit 17 stores information corresponding to the graph in Figure 6. In the graph in Figure 6, a straight line L1 is depicted. The straight line L1 shows a monotonically increasing trend in the region where the peak value P1 is greater than the second reference value A2, and in the region where the peak hold value P2 is greater than the third reference value A3. The straight line L1 shows the relationship between the peak value P1 and the first reference value A1. As the peak value P1 increases, the first reference value A1 increases. Therefore, in the region below the straight line L1, PM is accumulating on the reactor 18. In the region above the straight line L1, PM is not accumulating on the reactor 18. By using this first criterion A1, the control circuit 17 can appropriately determine whether or not PM is accumulating on the reactor 18, even if the peak value P1 fluctuates.
[0044] (Other embodiments) The exhaust gas purification device and control circuit according to the present invention are not limited to the exhaust gas purification device 11, but can be modified within the scope of its gist.
[0045] In step S4, the control circuit 17 may determine whether the peak value P1 is greater than the second reference value A2 and whether the peak hold value P2 is greater than the third reference value A3.
[0046] Furthermore, in step S5, if the peak hold value P2 is less than or equal to the first reference value A1, the control circuit 17 may determine that PM has accumulated on the reactor 18. If the peak hold value P2 is greater than the first reference value A1, the control circuit 17 may determine that no PM has accumulated on the reactor 18.
[0047] In step S8, the control circuit 17 does not need to stop the operation of the injector (not shown) injecting fuel.
[0048] In addition, PM may accumulate in reactor 18 in the straight line L1. [Explanation of Symbols]
[0049] 10: Vehicles 11: Exhaust purifier 12: Power supply 13:Power circuit 13a: Primary circuit 13b: Secondary circuit 14: Current sensor 15: Inverting Circuit 16: Peak Hold Circuit 17: Control circuit 18: Reactor 20: Internal combustion engine 130: Trans 131: Switch 132: Diode A1: First reference value A2: Second reference value A3: Third reference value I1: Primary current I2: Secondary current P1: Peak value P2: Peak Hold Value R1: Intake path R2: Exhaust path
Claims
1. The exhaust gas purification system comprises a power supply, a power supply circuit, a reactor, a current sensor, and a control circuit. The power supply circuit generates a secondary voltage by boosting the primary voltage generated by the power supply. The reactor generates plasma using the secondary voltage generated by the power supply circuit to purify the exhaust gas of the internal combustion engine. The current sensor detects the primary current generated in the power supply circuit along with the primary voltage, If the absolute value of the peak hold value of the primary current detected by the current sensor is smaller than the first reference value, the control circuit causes the power supply circuit to increase the secondary voltage. Exhaust gas purification device.
2. If the peak value of the primary current immediately before the reactor discharges is less than the second reference value, or if the absolute value of the peak hold value of the primary current immediately after the reactor discharges is less than the third reference value, the control circuit shall not increase the secondary voltage of the power supply circuit. The exhaust gas purification device according to claim 1.
3. As the peak value of the primary current immediately before the reactor discharges increases, the first reference value increases. The exhaust gas purification device according to claim 1.