JP2020076327A - Purification system - Google Patents

Abstract

To appropriately purify exhaust with a post treatment section without degrading fuel efficiency.SOLUTION: A purification system 1 comprises: a DPF 33 which is installed in an exhaust passage 30 where exhaust of an engine 10 flows and purifies exhaust; a heater 70 which is installed at an upstream side of the DPF 33 on the exhaust passage 30 and heats the exhaust; an electric supercharger 50 which compresses intake air flowing to the engine 10; a detection section 80 which detects a temperature and a flow rate of the exhaust; and a control device 90 which causes the electric supercharger 50 to send the intake air to the engine 10 and the heater 70 to heat the exhaust of the engine 10 when the temperature of the exhaust is lower than a predetermined temperature T1 and the flow rate of the exhaust is lower than a predetermined amount Q1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a purification system that purifies exhaust gas.

  A purifying device for purifying exhaust gas is installed in an exhaust passage of a vehicle such as a truck. The purification device has, for example, a filter that collects particulate matter in exhaust gas, and performs a regeneration process in which the collected particulate matter is burned by high-temperature exhaust gas. In order to promote the regeneration process, for example, a method is adopted in which combustion is injected into the exhaust gas on the upstream side of the purification device in the exhaust passage to raise the temperature of the exhaust gas.

Japanese Patent Publication No. 2009-523941

  However, when the fuel is injected into the exhaust passage instead of inside the engine as described above, the fuel injection does not contribute to the output of the engine, which may lead to deterioration of fuel efficiency.

  Therefore, the present invention has been made in view of these points, and an object of the present invention is to appropriately purify exhaust gas by a post-processing unit without deteriorating fuel efficiency.

  In one aspect of the present invention, a post-treatment unit that is provided in an exhaust passage through which engine exhaust flows and purifies the exhaust, and a heating unit that is provided upstream of the post-treatment unit in the exhaust passage and heats the exhaust Section, an electric supercharger that compresses intake air flowing to the engine, a detection unit that detects the temperature and flow rate of the exhaust gas, the temperature of the exhaust gas is lower than a predetermined temperature, and the flow rate of the exhaust gas is a predetermined amount. And a control unit that sends intake air to the engine by the supercharger and heats exhaust gas of the engine by the heating unit.

  Further, when the temperature of the exhaust gas is lower than the predetermined temperature, the flow rate of the exhaust gas is lower than a predetermined amount, and the load of the engine is lower than a predetermined value at the time of low load, the control unit controls the excess The intake air may be sent to the engine by a feeder, and the exhaust gas of the engine may be heated by the heating unit.

  Further, the control unit may acquire the traveling state of the vehicle and estimate that the vehicle is traveling at a low load when the vehicle is traveling on a downhill.

  Further, the post-treatment unit may be a filter that collects the particulate matter in the exhaust gas.

  According to the present invention, there is an effect that the exhaust gas can be appropriately purified by the post-processing unit without deteriorating the fuel consumption.

It is a schematic diagram for explaining the composition of the purification system 1 concerning one embodiment of the present invention. It is a flow chart for explaining an example of operation of purification system 1.

<Structure of purification system>
The configuration of the purification system according to one embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic diagram for explaining the configuration of a purification system 1 according to one embodiment. The purification system 1 is a system for purifying engine exhaust gas, and is installed in a vehicle such as a truck here. As shown in FIG. 1, the purification system 1 includes an engine 10, a power generator 14, an intake passage 20, an exhaust passage 30, a turbocharger 40, an electric supercharger 50, a heating device 70, and a bypass. It has 74, the detection part 80, and the control apparatus 90.

  The engine 10 burns and expands a mixture of fuel injected into a cylinder (combustion chamber) and intake air to generate power. The engine 10 is, for example, a diesel engine, but is not limited to this and may be, for example, a gasoline engine. In the engine 10, intake air is sucked into the cylinder, and exhaust gas after combustion is discharged from the cylinder.

  The power generator 14 generates power via a belt 14 a connected to the engine 10 here, and supplies power to the battery 16. The power generation device 14 may generate power during brake regeneration (for example, brake regeneration when the vehicle travels on a downhill) and supply electric power to the electric supercharger 50 and the heating device 70 that are loads. Note that fuel is not injected into the engine 10 during brake regeneration.

  The intake passage 20 is a passage through which intake air flows to the engine 10. The intake passage 20 is provided with an air cleaner 22, a CAC (Charge Air Cooler) 24, a valve 26, and a CAC 28. The compressor 44 of the turbocharger 40 and the electric supercharger 50 are also provided in the intake passage 20.

  The air cleaner 22 removes foreign matter in intake air. The CAC 24 cools the intake air that has been compressed by the compressor 44 and has increased in temperature. The valve 26 is an opening / closing valve provided in a bypass 26a that bypasses the electric supercharger 50, and intake air flows through the bypass 26a when opened. The CAC 28 is provided closer to the engine 10 than the electric supercharger 50, and cools the intake air compressed by the electric supercharger 50, for example.

  The exhaust passage 30 is a passage through which the exhaust gas of the engine 10 flows. The exhaust passage 30 is provided with a DOC (Diesel Oxidation Catalyst) 32, a DPF (Diesel Particulate Filter) 33, an injection unit 35, an SCR (Selective Catalytic Reduction) 36, and a return passage 38. The turbine 42 of the turbocharger 40, the heating device 70, and the bypass 74 are also provided in the exhaust passage 30. In the present embodiment, the DPF 33 corresponds to the purification unit that purifies the exhaust gas.

  The DOC 32 is a diesel oxidation catalyst, and efficiently oxidizes hydrocarbons in the exhaust gas that has passed through the turbine 42 to raise the temperature of the exhaust gas. The DPF 33 is a filter that collects particulate matter (PM) in exhaust gas. Note that the DPF 33 performs a regeneration process of burning the trapped particulate matter when the temperature of the exhaust gas rises.

The injection unit 35 injects urea water that becomes ammonia into the exhaust passage 30. The SCR 36 has a catalyst for reducing NOx in the exhaust gas and reacts NOx with ammonia to reduce harmless nitrogen and water. The purification rate of the exhaust gas by the SCR 36 increases as the temperature of the exhaust gas increases.
The return passage 38 is a passage for returning a part of the exhaust gas discharged from the engine 10 to the intake passage 20. The recirculation path 38 is provided with a cooling unit 38a for cooling the exhaust gas and a valve 38b for adjusting the recirculation amount of the exhaust gas.

  The turbocharger 40 is a supercharger that uses the flow of exhaust gas to increase the density of intake air. The turbocharger 40 has a turbine 42 provided in the exhaust passage 30 and a compressor 44 provided in the intake passage 20. The turbine 42 receives the energy of the exhaust gas and rotates. The compressor 44 is connected to the turbine 42 via a connecting shaft. The intake air is compressed by the compressor 44 rotating together with the turbine 42.

  The electric supercharger 50 is an electric supercharger that compresses intake air flowing into the engine 10, and is provided separately from the turbocharger 40. The electric supercharger 50 is provided upstream of the engine 10 in the intake passage 20. The electric supercharger 50 has a motor 51 that rotates by receiving electric power from the battery 16 and the power generator 14. That is, the electric supercharger 50 compresses intake air and supplies it to the engine 10 without using exhaust gas.

  The heating device 70 is a heating unit that heats the exhaust gas, and is provided in the exhaust passage 30 on the upstream side of the DPF 33. Here, the heating device 70 is provided on the upstream side of the DOC 32, but is not limited to this, and may be provided between the DOC 32 and the DPF 33, for example. The heating device 70 is, for example, an electric heater and receives electric power from the battery 16 or the power generation device 14 to heat the exhaust gas. As a result, the exhaust gas that has been heated by the heating device 70 and has increased in temperature passes through the DPF 33, and the regeneration process in the DPF 33 is promoted.

  The bypass 74 is a passage that bypasses the heating device 70 in the exhaust passage 30. The detour 74 branches from the point between the turbine 42 and the heating device 70 in the exhaust path 30, and joins at the point between the heating device 70 and the detection unit 80. When flowing through the bypass 74, the exhaust gas does not pass through the heating device 70 and flows to the DPF 33.

  The bypass 75 is provided with a valve 75. The valve 75 is, for example, a butterfly valve, and adjusts the opening degree to adjust the flow rate of exhaust gas. When the valve 75 is closed, the exhaust gas is heated as it passes through the heating device 70 without going to the bypass 74. When the valve 75 is open, the exhaust gas flows to the DPF 33 via the bypass 74 without going to the heating device 70.

The detection unit 80 detects the temperature and flow rate of exhaust gas. The detection unit 80 includes a temperature sensor that detects the temperature of exhaust gas and a flow rate sensor that detects the flow rate of exhaust gas. The temperature sensor is provided near the entrance of the DOC 32, for example. The detection unit 80 may include a sensor that measures the amount of intake air, and may calculate the flow rate of exhaust gas from the amount of intake air measured by the sensor.
Further, the detection unit 80 may detect the operating condition of the engine 10 (for example, the rotation or load condition of the engine 10). Further, the detection unit 80 may detect the traveling state of the vehicle. The detection unit 80 detects, for example, whether or not the road on which the vehicle is traveling is a downhill, by using map information or a sensor mounted on the vehicle. The detection result of the detection unit 80 is output to the control device 90.

  The control device 90 is an electronic control device (Electric Control Unit) including a microcomputer having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The control device 90 controls the operation of each device described above.

  In the present embodiment, the control device 90 controls the operation of the electric supercharger 50 and the heating device 70 based on the temperature and flow rate of the exhaust gas flowing through the exhaust passage 30. That is, the control device 90 controls the operations of the electric supercharger 50 and the heating device 70 based on the temperature and flow rate of the exhaust gas detected by the detection unit 80.

  For example, when the temperature of the exhaust gas is lower than the predetermined temperature T1 and the flow rate of the exhaust gas is lower than the predetermined amount Q1, the control device 90 sends the intake air to the engine 10 by the electric supercharger 50 (supercharging control), Moreover, the exhaust gas is heated by the heating device 70 (heating control). The control device 90 supplies the electric power stored in the battery 16 or the electric power generated by the power generation device 14 to the electric supercharger 50 and the heating device 70 to perform supercharging control and heating control. As a result, the amount of intake air sent to the engine 10 by the electric supercharger 50 is increased, so that the amount of exhaust gas flowing from the engine 10 to the DPF 33 is increased. Then, the heating device 70 provided on the upstream side of the DPF 33 in the exhaust passage 30 heats the exhaust gas, so that the exhaust gas whose temperature rises early passes through the DPF 33. As a result, the regeneration treatment of the particulate matter collected by the DPF 33 is promoted. Further, by performing the heating control described above, it is not necessary to perform the conventional process of injecting fuel into the exhaust passage 30 to raise the temperature of the exhaust gas, and thus it is possible to suppress deterioration of fuel efficiency due to fuel injection.

  On the other hand, when the temperature of the exhaust gas is higher than the predetermined temperature T1 or the flow rate of the exhaust gas is higher than the predetermined amount Q1, the control device 90 determines that the exhaust gas that allows the DPF 33 to perform the regeneration process is flowing, and the electric overflow is performed. Power is not supplied to the feeder 50 and the heating device 70, and the above-described supercharging control and heating control are not performed. For example, the control device 90 causes the exhaust gas to flow to the bypass 74 when the engine 10 has a high load and high rotation speed, and suppresses the heating of the exhaust gas by the heating device 70. Accordingly, it is possible to suppress the occurrence of pressure loss due to the exhaust gas passing through the heating device 70.

  The control device 90 may control the operation of the electric supercharger 50 and the heating device 70 in consideration of the load state of the engine 10 in addition to the temperature and flow rate of the exhaust gas. Specifically, the control device 90, when the temperature of the exhaust gas is lower than the predetermined temperature T1, the flow rate of the exhaust gas is less than the predetermined amount Q1, and the load of the engine 10 is under the low load of less than the predetermined value F1. The intake air is sent to the engine 10 by the electric supercharger 50, and the exhaust gas is heated by the heating device 70. As a result, when the DPF 33 needs to be activated, the exhaust gas whose temperature has been raised can be sent to the DPF 33, so that the DPF 33 can be activated early.

  The control device 90 may estimate the load state of the engine 10 from the traveling state of the vehicle. For example, the control device 90 acquires the traveling state of the vehicle from the detection result of the detection unit 80 and estimates that the engine 10 is in the low load / low rotation state when the vehicle is traveling on a downhill. The control device 90 may also estimate that the engine 10 is in the low load / low rotation state even when the vehicle is traveling on a flat road at high speed. The control device 90 may acquire the traveling state of the vehicle from the map information.

<Operation example of purification system>
An operation example of the purification system 1 described above will be described with reference to FIG.

  FIG. 2 is a flowchart for explaining an operation example of the purification system 1. The processing illustrated in FIG. 2 is realized by the CPU of the control device 90 executing a program.

  The process of FIG. 2 is started while the vehicle is traveling. Here, it is assumed that the vehicle is traveling downhill. Therefore, the engine 10 is in a low rotation / low load state and the temperature of the exhaust gas is low.

  First, the control device 90 detects the temperature and flow rate of the exhaust gas in the exhaust passage 30 (step S102). Specifically, the control device 90 detects the temperature and flow rate of exhaust gas by the detection unit 80.

  Next, the control device 90 detects the state of the engine 10 (step S104). For example, the control device 90 detects the rotation and load states of the engine 10 based on the detection result of the detection unit 80. Since the vehicle is traveling downhill as described above, the control device 90 determines that the engine 10 is in the low rotation / low load state. Note that the processes of steps S102 and S104 may be executed simultaneously or in reverse order.

  Next, the control device 90 determines whether or not the supercharging by the electric supercharger 50 and the heating condition by the heating device 70 are satisfied (step S106). For example, the control device 90 determines whether or not the conditions that the temperature of the exhaust gas is lower than the predetermined temperature T1, the flow rate of the exhaust gas is less than the predetermined amount Q1 and the engine 10 is in the low load state are satisfied. The condition is not limited to the above, and the control device 90 may determine that the condition is satisfied when the temperature of the exhaust gas is lower than the predetermined temperature T1 and the flow rate of the exhaust gas is lower than the predetermined amount Q1.

  When the condition is satisfied in step S106 (Yes), the control device 90 supplies electric power to the electric supercharger 50 to supercharge intake air to the engine 10 (step S108). At this time, the control device 90 supplies the electric power of the battery 16 to the electric supercharger 50, or supplies the electric power generated by the power generation device 14 to the electric supercharger 50 during brake regeneration. By supercharging the intake air, the amount of exhaust gas from the engine 10 also increases.

  Next, the control device 90 supplies electric power to the heating device 70 to heat the exhaust gas flowing through the exhaust passage 30 (step S110). At this time, the control device 90 supplies the electric power of the battery 16 to the heating device 70, or supplies the electric power generated by the power generation device 14 to the heating device 70 during brake regeneration. Since the exhaust gas is heated by the heating device 70 located on the upstream side of the DPF 33, the exhaust gas whose temperature has risen passes through the DPF 33, and the regeneration process by the DPF 33 is accelerated.

<Effects of this embodiment>
In the purification system 1 described above, when the temperature of the exhaust gas is lower than the predetermined temperature T1 and the flow rate of the exhaust gas is less than the predetermined amount Q1, the intake air is sent to the engine 10 by the electric supercharger 50 and the exhaust passage 30 is provided. The exhaust device is heated by the heating device 70 provided on the upstream side of the DPF 33.
As a result, the amount of intake air sent to the engine 10 by the supercharging of the electric supercharger 50 increases, and the amount of exhaust gas flowing from the engine 10 to the DPF 33 increases. Then, the heating device 70 provided on the upstream side of the DPF 33 in the exhaust passage 30 heats the exhaust gas, so that the exhaust gas whose temperature rises early passes through the DPF 33. As a result, the regeneration treatment of the particulate matter collected by the DPF 33 is promoted. Further, since the heating device 70 heats the exhaust gas, the conventional process of injecting the fuel into the exhaust passage 30 to raise the temperature of the exhaust gas is not necessary, so that the fuel consumption deterioration due to the fuel injection can be suppressed.

  In the above, the purification system 1 purifies the exhaust gas of the engine of the vehicle, but is not limited to this. For example, the purification system 1 may purify the exhaust gas of a stationary engine mounted on a power generator or the like, or may purify the exhaust gas of an engine mounted on an industrial device such as a construction machine or a ship.

  Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. is there. For example, the specific embodiment of the distribution / integration of the device is not limited to the above-described embodiment, and all or a part thereof may be functionally or physically distributed / integrated in arbitrary units to be configured. You can Further, a new embodiment that occurs due to an arbitrary combination of a plurality of embodiments is also included in the embodiment of the present invention. The effect of the new embodiment produced by the combination has the effect of the original embodiment.

1 Purification System 10 Engine 30 Exhaust Path 33 DPF
50 Electric Supercharger 70 Heating Device 80 Detector 90 Control Device

Claims (4)

A post-processing unit provided in an exhaust passage through which the exhaust gas of the engine flows, for purifying the exhaust gas;
A heating unit which is provided on the upstream side of the post-treatment unit in the exhaust passage and heats the exhaust gas;
An electric supercharger that compresses intake air flowing to the engine,
A detection unit for detecting the temperature and flow rate of the exhaust gas,
When the temperature of the exhaust gas is lower than a predetermined temperature and the flow rate of the exhaust gas is less than a predetermined amount, the supercharger sends intake air to the engine and controls the heating unit to heat the exhaust gas of the engine. Department,
Purification system. The control unit is
When the temperature of the exhaust gas is lower than the predetermined temperature, the flow rate of the exhaust gas is less than a predetermined amount, and the load of the engine is at a low load lower than a predetermined value, intake air is taken from the engine by the supercharger. And heating the exhaust of the engine by the heating unit,
The purification system according to claim 1. The control unit is
Get the running status of the vehicle,
When the vehicle is traveling downhill, it is estimated that the load is low,
The purification system according to claim 2. The post-treatment unit is a filter that collects the particulate matter in the exhaust gas,
The purification system according to any one of claims 1 to 3.

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