JP7443806B2 - 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 purification device in which a heating device is disposed between an upstream NOx purification catalyst and a downstream NOx purification catalyst, and these are housed in one case. In this exhaust purification device, for example, immediately after starting the internal combustion engine, the upstream NOx purification catalyst and the downstream NOx purification catalyst can be activated early by heating with the heating device.

JP 2019-132168 Publication

However, the exhaust purification device of Patent Document 1 has room for improvement in terms of space saving.

An object of the present disclosure is to provide an exhaust purification device and a vehicle that can achieve further space savings while ensuring NOx purification efficiency.

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. An exhaust purification device comprising: a second NOx purification catalyst provided downstream of the NOx purification catalyst; and a heating section provided between the first NOx purification catalyst and the second NOx purification catalyst. , the specific heat of the first NOx purification catalyst is smaller than the specific heat of the second NOx purification catalyst.

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, further space saving can be achieved while ensuring NOx purification efficiency.

A schematic diagram showing the configuration of an exhaust purification device according to an 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.

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 in the urea water injection devices 2 and 8, the on/off of power supply to the heating unit 4, and the like. In FIG. 1, dotted arrows indicate control signals output from the control section 10 to the heating section 4 and the urea water injection devices 2 and 8. Note that, as the control section 10, for example, an ECU (Electronic Control Unit) can be mentioned.

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 order from the upstream side, a urea water injection device 2, an SCR (Selective Catalytic Reduction) 3, a heating section 4, and an SCR 5.

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.

SCR3 uses a material with a relatively low specific heat as a carrier. On the other hand, SCR5 uses a material with a relatively large specific heat as a carrier. That is, the specific heat of SCR3 is smaller than the specific heat of SCR5.

For example, SCR3 uses metal as a carrier. As the metal, for example, stainless steel or the like can be used.

For example, SCR5 uses ceramic as a carrier. As the ceramic, for example, silicon carbide or cordierite can be used.

Note that the heat capacity of SCR3 is smaller than that of SCR5. Further, the activation temperature range of SCR3 and the activation temperature range of SCR5 are the same.

The heating unit 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 the heat radiation of the heating 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 heating unit 4 is controlled by 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.

The second catalytic converter 12 accommodates, in order from the upstream side, 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.

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 activation temperature range of SCR9 is higher than the activation temperature range of SCR3 and SCR5.

Further, the SCR 9 may have 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 effects of the exhaust purification device 100 will be explained below.

The exhaust purification device 100 includes an SCR 3 provided on the upstream side in the flow direction of exhaust gas, an SCR 5 provided on the downstream side of the SCR 3 in the flow direction of exhaust gas, and a heating section 4 provided between the SCR 3 and the SCR 5. , and is characterized in that the specific heat of SCR3 is smaller than the specific heat of SCR5.

Therefore, the temperature of the SCR 3 is easily raised by the exhaust gas flowing from the upstream side thereof, and NOx can be efficiently purified. Therefore, it is possible to downsize the SCR 3 (more specifically, to shorten the length of the SCR 3 in the exhaust gas flow direction). Therefore, it is possible to downsize the first catalytic converter 11 (more specifically, to shorten the length of the first catalytic converter 11 in the exhaust gas flow direction).

On the other hand, since the SCR 3 has a small specific heat, its temperature tends to decrease as the exhaust gas temperature decreases, but an SCR 5 having a large specific heat is provided downstream of the SCR 3. Therefore, even when the temperature of the exhaust gas decreases, NOx can be efficiently purified by the SCR 5 whose temperature has increased due to heat radiation from the heating section 4.

Therefore, the exhaust gas purification device 100 can achieve further space saving while ensuring NOx purification efficiency.

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.

Furthermore, 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 embodiments described above, and can be modified and implemented as appropriate 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. You may.

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, and the heating unit 4 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, and the heating unit 4 may be provided within 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 heating 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 saving space in an exhaust purification device that purifies exhaust gas.

1 Exhaust pipe 2, 8 Urea water injection device (reducing agent supply device)
3, 5, 9 SCR
4 Heating section 6 DOC
7 DPF
10 Control part 11 First catalytic converter 12 Second catalytic converter 13 ASC
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;
An exhaust purification device comprising: a heating section provided between the first NOx purification catalyst and the second NOx purification catalyst,
The specific heat of the first NOx purification catalyst is smaller than the specific heat of the second NOx purification catalyst.
Exhaust purification device. The carrier of the first NOx purification catalyst is metal,
The carrier of the second NOx purification catalyst is ceramic,
The exhaust gas purification device according to claim 1. further comprising a casing that houses the first NOx purification catalyst, the heating section, and the second NOx purification catalyst in series,
further accommodating a reducing agent supply device for supplying a reducing agent into the housing , respectively upstream of the first NOx purification catalyst and upstream of the second NOx purification catalyst;
The first NOx purification catalyst and the second NOx purification catalyst are selective reduction catalysts that promote reduction of NOx by a substance generated from the reducing agent.
The exhaust gas purification device according to claim 1 or 2. In the flow direction of exhaust gas, a second reducing agent supply device is provided on the downstream side of the casing to supply the reducing agent into the casing; The second housing further includes a third NOx purification catalyst that promotes the reduction of NOx by the substance, and a decomposition catalyst that decomposes the substance downstream of the third NOx purification catalyst. ,
The exhaust gas purification device according to claim 3. The reducing agent is urea water,
the substance is ammonia,
The exhaust gas purification device according to claim 3 or 4. The exhaust purification device is a device that purifies exhaust gas discharged from a diesel engine.
The exhaust gas purification device according to any one of claims 1 to 5. A vehicle comprising the exhaust purification device according to any one of claims 1 to 6 .

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