JP7443809B2 - Exhaust purification equipment and vehicles - Google Patents

Description

The present disclosure relates to an exhaust purification device and a vehicle that purify exhaust gas.

2. Description of the Related Art Conventionally, an exhaust purification device is known in which a plurality of NOx purification catalysts for reducing NOx in exhaust gas are provided in an exhaust pipe through which exhaust gas discharged from an internal combustion engine flows.

For example, Patent Document 1 discloses an exhaust gas purification device in which a heating device is disposed between an upstream NOx purification catalyst and a downstream NOx purification catalyst to heat exhaust gas flowing between them.

JP 2019-132168 Publication

However, in the exhaust purification device of Patent Document 1, there is room for improvement in activation of the NOx purification catalyst.

An object of one aspect of the present disclosure is to provide an exhaust purification device and a vehicle that can activate multiple NOx purification catalysts at an early stage.

An exhaust gas purification device according to an aspect of the present disclosure includes: a first NOx purification catalyst provided upstream in a flow direction of exhaust gas discharged from an internal combustion engine; and a first NOx purification catalyst provided in the flow direction of the exhaust gas. a second NOx purification catalyst provided downstream of the first NOx purification catalyst, a heat dissipation section provided between the first NOx purification catalyst and the second NOx purification catalyst, and It has a reducing agent supply device that supplies a reducing agent on the upstream side, and a control section that controls the respective operations of the heat radiating section and the reducing agent supply device, and the control section is configured to control the internal combustion engine immediately after starting the internal combustion engine. In order to raise the temperature of the exhaust gas, the heat radiating section starts radiating heat, and then, when the temperature of the exhaust gas downstream of the second NOx purification catalyst exceeds a predetermined threshold, the reducing agent supply device The injection of the reducing agent is started.

A vehicle according to one aspect of the present disclosure includes an exhaust purification device according to one aspect of the present disclosure.

According to the present disclosure, multiple NOx purification catalysts can be activated early.

A schematic diagram showing the configuration of an exhaust purification device according to an embodiment of the present disclosure Flowchart showing the operation of the control unit according to the embodiment of the present disclosure

Embodiments of the present disclosure will be described in detail below with reference to the drawings.

The configuration of an exhaust purification device 100 according to an embodiment of the present disclosure will be described using FIG. 1. FIG. 1 is a schematic diagram showing an example of the configuration of an exhaust gas purification device 100 according to the present embodiment.

The exhaust purification device 100 is a device that is mounted on a vehicle (not shown) and purifies exhaust gas discharged from an internal combustion engine (not shown). In this embodiment, a case will be described in which the internal combustion engine is a diesel engine, but the present invention is not limited to this, and the internal combustion engine may be, for example, a gasoline engine. Further, the exhaust gas purification device 100 can be applied not only to internal combustion engines of vehicles but also to ships and stationary internal combustion engines, for example.

As shown in FIG. 1, the exhaust purification device 100 includes a control section 10, a first catalytic converter 11, and a second catalytic converter 12.

The control unit 10 controls the injection amount and injection timing of urea water (an example of a reducing agent) in the urea water injection devices 2 and 8, and the on/off of power supply to the heat radiating unit 4. An example of the control unit 10 is an ECU (Electronic Control Unit).

In FIG. 1, dotted arrows indicate control signals output from the control section 10 to the heat radiation section 4 and the urea water injection devices 2 and 8. Moreover, in FIG. 1, a dashed-dotted arrow indicates a signal output from a temperature sensor 14, which will be described later, to the control unit 10.

Details of the operation of the control unit 10 will be described later using FIG. 2.

The first catalytic converter 11 and the second catalytic converter 12 are provided in series in the exhaust pipe 1.

An upstream end (left side in the figure) of the exhaust pipe 1 is connected to, for example, a downstream end of an exhaust manifold (not shown) of a diesel engine. Exhaust gas discharged from the exhaust manifold flows through the exhaust pipe 1 from the left side to the right side in the figure. In FIG. 1, solid arrows indicate the flow direction of exhaust gas.

The first catalytic converter 11 is a housing (case) that can be attached to and detached from the exhaust pipe 1 . For example, the first catalytic converter 11 is located closer to the diesel engine than the second catalytic converter 12 is.

The first catalytic converter 11 accommodates in series a urea water injection device 2, an SCR (Selective Catalytic Reduction) 3, a heat radiation section 4, an SCR 5, and a temperature sensor 14 in order from the upstream side.

The urea water injection device 2 (an example of a reducing agent supply device) is a device that injects urea water (an example of a reducing agent) into the first catalytic converter 11. The urea water injected by the urea water injection device 2 is hydrolyzed. The ammonia thus generated (an example of a substance generated from the reducing agent) is supplied to the SCRs 3 and 5. As described above, the injection amount and injection timing of urea water are controlled by the control unit 10.

SCR3 (an example of a first NOx purification catalyst) and SCR5 (an example of a second NOx purification catalyst) are catalysts that reduce NOx in exhaust gas to nitrogen using ammonia generated from urea water.

The carrier for SCR3 and the carrier for SCR5 may be the same or different. As the carrier, metals (for example, stainless steel), ceramics (for example, silicon carbide or cordierite), etc. can be used.

The heat radiating section 4 is, for example, a member (for example, made of stainless steel, ceramics, etc.) that radiates heat by supplying power from a battery (not shown). The exhaust gas flowing between the SCR 3 and the SCR 5 is heated by heat radiation from the heat radiation section 4 . As a result, the temperature of the SCR 5 increases easily. Note that, as described above, on/off of power supply to the heat radiating section 4 is controlled by the control section 10.

The temperature sensor 14 is provided downstream of the SCR 5. The temperature sensor 14 periodically detects the temperature of the exhaust gas that has passed through the SCR 5, and outputs a signal (see the dashed-dotted arrow in the figure) indicating the temperature (hereinafter referred to as detected temperature) to the control unit 10.

The second catalytic converter 12 is a housing (case) that can be attached to and detached from the exhaust pipe 1 . The second catalytic converter 12 is provided at a position farther from the diesel engine than the first catalytic converter 11.

In the second catalytic converter 12, a DOC (Diesel Oxidation Catalyst) 6, a DPF (Diesel Particulate Filter) 7, a urea water injection device 8, an SCR 9, and an ASC (Ammonia Slip Catalyst) 13 are housed in series in order from the upstream side. There is.

DOC6 is a catalyst that oxidizes nitrogen monoxide and hydrocarbons in exhaust gas.

The DPF 7 is a filter that collects and removes particulate matter (PM) in exhaust gas.

The urea water injection device 8 is a device that injects urea water into the second catalytic converter 12 . The urea water injected by the urea water injection device 8 is hydrolyzed. Ammonia generated thereby is supplied to the SCR 9. As described above, the injection amount and injection timing of urea water are controlled by the control unit 10.

SCR9 is a catalyst that reduces NOx in exhaust gas to nitrogen using ammonia generated from urea water.

The active temperature range of SCR9 is higher than the active temperature range of SCR3 and SCR5, for example.

Further, the SCR 9 may use a metal (for example, stainless steel) as a carrier or a ceramic (for example, silicon carbide or cordierite) as a carrier.

ASC13 (an example of a decomposition catalyst) is a catalyst that oxidizes and decomposes ammonia that was not completely consumed in SCR9. This can prevent ammonia from being discharged into the atmosphere.

The configuration of the exhaust purification device 100 has been described above.

Next, the operation of the control section 10 will be explained using FIG. 2. FIG. 2 is a flowchart showing an example of the operation of the control unit 10. The flow shown in FIG. 2 is started, for example, immediately after starting the diesel engine.

First, the control unit 10 starts supplying power to the heat radiating unit 4 and causes the heat radiating unit 4 to start radiating heat (step S1).

Next, the control unit 10 determines whether the detected temperature notified from the temperature sensor 14 exceeds a predetermined threshold (step S2).

The threshold value is, for example, the lower limit value of the activation temperature range of SCR5. Alternatively, the threshold value may be, for example, the smaller of the lower limit value of the active temperature range of SCR3 and the lower limit value of the active temperature range of SCR5.

If the detected temperature does not exceed the threshold (step S2: NO), the flow returns to step S2. That is, the control unit 10 determines again whether the detected temperature exceeds the threshold value.

On the other hand, if the detected temperature exceeds the threshold (step S2: YES), the control unit 10 causes the urea water injection device 2 to start injection of urea water (step S3). Note that at this time, the control unit 10 may cause the urea water injection device 8 to start jetting the urea water.

The operation of the control unit 10 has been described above.

Next, the effects of the exhaust purification device 100 will be explained below.

The exhaust purification device 100 starts radiating heat from the heat radiating section 4 immediately after starting the diesel engine, and starts injecting urea water from the urea water injection device 2 when the temperature of the exhaust gas on the downstream side of the SCR 5 exceeds a threshold value. It is characterized by

Therefore, the temperature of the SCR 3 on the upstream side increases quickly due to the exhaust gas, and the temperature of the SCR 5 on the downstream side increases quickly due to heat radiation from the heat radiating section 4, so that the entire SCRs 3 and 5 can be activated quickly. In addition, the injection of urea water is started when the temperature of the exhaust gas downstream of SCR5 exceeds the threshold (in other words, when both SCR3 and 5 are activated), so urea water is not wasted. Can be injected.

Further, in the exhaust gas purification device 100, the SCRs 3 and 5 and the SCR 9 having different activation temperature ranges are housed in separate housings (for example, the first catalytic converter 11 and the second catalytic converter 12). Therefore, the second catalytic converter 12 can be provided at a location away from the diesel engine where sufficient installation space can be secured. Therefore, the size of the SCR 9 accommodated in the second catalytic converter 12 can be increased, and the NOx purification efficiency can be further improved.

Further, in the exhaust gas purification device 100, a urea water injection device 2 is provided corresponding to the SCRs 3 and 5, and a urea water injection device 8 is provided corresponding to the SCR 9. Therefore, hydrolysis can be promoted in each of the first catalytic converter 11 and the second catalytic converter 12, and NOx can be efficiently purified in each of the SCRs 3, 5, and 9.

Further, in the exhaust purification device 100, the second catalytic converter 12 is provided with a DOC 6 and a DPF 7. Therefore, oxidation of carbon monoxide and hydrocarbons and collection of particulate matter can be performed more reliably.

Furthermore, in the exhaust gas purification device 100, the first catalytic converter 11 and the second catalytic converter 12 are each independently attachable to and detachable from the exhaust pipe 1. Therefore, maintenance etc. become easy.

The effects of the exhaust purification device 100 have been described above.

Note that the present disclosure is not limited to the above-described embodiments, and can be implemented with appropriate modifications without departing from the spirit of the present disclosure. Each modification will be explained below.

In the embodiment, all the components shown in FIG. 1 are referred to as the exhaust purification device 100, but among the components shown in FIG. The control unit 10 may also be referred to as an exhaust purification device 100.

Further, in the embodiment, the case where the exhaust purification device 100 includes the second catalytic converter 12 has been described as an example, but the present invention is not limited thereto. For example, the exhaust gas purification device 100 may have a configuration that does not include the DOC 6, DPF 7, urea water injection device 8, SCR 9, ASC 13, and second catalytic converter 12 among the components shown in FIG.

Further, in the embodiment, the case where the urea water injection device 2, the SCRs 3 and 5, the heat radiation section 4, and the temperature sensor 14 are housed in the first catalytic converter 11 has been described as an example, but the present invention is not limited thereto. For example, the urea water injection device 2, the SCRs 3 and 5, the heat radiation section 4, and the temperature sensor 14 may be provided in the exhaust pipe 1 without being housed in the first catalytic converter 11.

Further, in the embodiment, the case where the first catalytic converter 11 does not include an ASC has been described as an example, but the present invention is not limited to this. For example, the first catalytic converter 11 may include an ASC downstream of the SCR 5. Thereby, ammonia in the exhaust gas flowing out from the first catalytic converter 11 can be reduced. Therefore, ammonia is supplied to the DOC6, and oxidation of ammonia by the DOC6 can be suppressed. As a result, the generation of NOx caused by the oxidation of ammonia generated from urea water can be suppressed.

Further, in the embodiment, the case where the urea water injection device 2 is provided only on the upstream side of the SCR 3 in the first catalytic converter 11 has been described as an example, but the present invention is not limited to this. For example, in addition to the urea water injection device 2, the first catalytic converter 11 may further include a urea water injection device between the heat radiation section 4 and the SCR 5. Thereby, the NOx purification efficiency in the SCR 5 can be further improved.

Further, in the embodiment, the case where the NOx purification catalyst is SCR 3, 5, or 9 has been described as an example, but the present invention is not limited thereto. Other selective reduction catalysts, NOx adsorption catalysts, or three-way catalysts may be used in place of SCRs 3, 5, and 9. In that case, a reducing agent other than urea water (eg, hydrocarbon, etc.) may be used.

Each modification example has been described above. Note that each modification may be implemented in combination.

The exhaust purification device and vehicle of the present disclosure are useful for early activation of a NOx purification catalyst that purifies exhaust gas.

1 Exhaust pipe 2, 8 Urea water injection device 3, 5, 9 SCR
4 Heat dissipation part 6 DOC
7 DPF
10 Control part 11 First catalytic converter 12 Second catalytic converter 13 ASC
14 Temperature sensor 100 Exhaust purification device

Claims (7)

a first NOx purification catalyst provided on the upstream side in the flow direction of exhaust gas discharged from the internal combustion engine;
a second NOx purification catalyst provided downstream of the first NOx purification catalyst in the flow direction of the exhaust gas;
a heat radiation section provided between the first NOx purification catalyst and the second NOx purification catalyst;
a reducing agent supply device that supplies a reducing agent on the upstream side of the first NOx purification catalyst;
a control unit that controls the operation of each of the heat radiating unit and the reducing agent supply device,
The control unit includes:
causing the heat radiating section to start radiating heat in order to raise the temperature of the exhaust gas immediately after starting the internal combustion engine;
Thereafter, when the temperature of the exhaust gas downstream of the second NOx purification catalyst exceeds a predetermined threshold, causing the reducing agent supply device to start injection of the reducing agent;
Exhaust purification device. The threshold value is
is the lower limit of the activation temperature range of the second NOx purification catalyst,
The exhaust gas purification device according to claim 1. further comprising a casing that houses the reducing agent supply device, the first NOx purification catalyst, the heat radiation section, and the second NOx purification catalyst in series;
The exhaust gas purification device according to claim 1 or 2. The first NOx purification catalyst and the second NOx purification catalyst are selective reduction catalysts that promote reduction of the NOx by a substance generated from the reducing agent.
The exhaust gas purification device according to claim 3. The casing further accommodates a decomposition catalyst that decomposes the substance downstream of the second NOx purification catalyst.
The exhaust gas purification device according to claim 4. The reducing agent is urea water,
the substance is ammonia,
The exhaust gas purification device according to claim 4 or 5. A vehicle comprising the exhaust purification device according to any one of claims 1 to 6.

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