JP2012067756A - Exhaust gas after-treatment device of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas after-treatment device of a diesel engine capable of avoiding deterioration in a fuel consumption ratio without performing control for narrowing down a throttle valve of air supply and exhaust, that is, control for reducing thermal efficiency of the engine and increasing an exhaust gas temperature to make DOC and DPF normal particularly in a low load of the engine.SOLUTION: In the exhaust gas after-treatment device of the diesel engine, a heating heat exchanger 6 storing heat in a heat receiving medium by heat exchange of heat of an exhaust gas after passage through DPF and the heat receiving medium is provided on a downstream side of the DPF 122, a heat radiating heat exchanger 7 radiating heat of the heat receiving medium in the exhaust gas by heat exchange of heat of the heat receiving medium stored by the heating heat exchanger 6 and the exhaust gas in an exhaust gas inlet part of the DOC is provided in the exhaust gas inlet part of the DOC 121 and a heat medium passage 8 is provided between the heating heat exchanger 6 and the heat radiating heat exchanger 7.

Description

  The present invention is used in a DPF (particulate matter removal device) regeneration device or the like of a diesel engine, and the exhaust gas at the outlet of an exhaust turbocharger passes through a DOC (oxidation catalyst) and a DPF (diesel particulate filter), and the DOC. The present invention relates to an exhaust gas aftertreatment device for a diesel engine that oxidizes fuel in exhaust gas, burns PM (particulate matter) in the exhaust gas after fuel oxidation with the DOC by the DPF, and purifies the exhaust gas.

FIG. 6 is an overall configuration diagram of a diesel engine including a DOC (oxidation catalyst) and a DPF (diesel particulate filter) device.
In FIG. 6, a diesel engine (hereinafter referred to as engine 100) includes an exhaust turbocharger 110 having an exhaust turbine 109 and a compressor 108 driven coaxially thereto, and is discharged from the compressor 108 of the supercharger 110. The air enters the air cooler 106 through the air pipe 107 and is cooled by the air cooler 106.
The air cooled by the air cooler 106 is controlled in its opening by the intake throttle valve 105, passes through the air supply pipe 104, and is sucked into the engine 100 from an air supply port provided for each cylinder.
In the engine 100, the high-pressure fuel accumulated in the common rail (pressure accumulator) 102 is controlled in injection timing and injection amount by the common rail control device 103, and the fuel provided for each cylinder at the injection timing and injection amount. It is injected from the injection valve 101. The injected high-pressure fuel is burned by mixing with the air.

Further, an EGR (exhaust gas recirculation) pipe 116 is branched from the middle of the exhaust collecting pipe 111, and a part of the exhaust gas 120 (EGR gas) passes through the EGR pipe 116 and is cooled by the EGR cooler 115, and the EGR valve 114. Then, the flow rate is controlled and the intake throttle valve 105 of the supply pipe 104 is introduced into the downstream portion.
The combustion gas burned in the engine 100, that is, the exhaust gas 120, drives the exhaust turbine 109 of the exhaust turbo supercharger 110 through the exhaust collecting pipe 111 in which exhaust ports provided for each cylinder are gathered. After serving as a power source for the compressor 108, the exhaust enters the DOC 121 of the exhaust gas aftertreatment device 1 through the exhaust pipe 112.

The DOC 121 is used to oxidize the fuel in the exhaust gas 120 and the temperature is raised, and then sent to the DPF 122 of the exhaust gas aftertreatment device 1.
In the DPF 122, the HC (hydrocarbon) component is oxidized by the DOC, and the PM (particulate matter) deposited on the DPF 122 is combusted by the reaction heat generated at this time. The exhaust gas after the combustion treatment is discharged from the exhaust outlet pipe 113 to the outside.

  In the patent document (Japanese Patent Laid-Open No. 2004-339971), particularly in FIG. 3, a fuel injection valve 43 is arranged between the downstream of the DOC 3 Aa and the DPF 3 Ab, and a predetermined amount from the fuel injection valve 43. An exhaust gas aftertreatment device for a diesel engine having a DOC and a DPF in which fuel is injected at a time to increase the temperature of the DPF 3A is shown.

JP 2004-339971 A

The exhaust gas aftertreatment device of the diesel engine shown in FIG. 6 supplies the fuel to the upstream side of the DOC 121 and oxidizes the fuel at the DOC 121 when the DPF 122 is regenerated. The temperature is raised to a combustion temperature (generally 600 to 650 ° C.).
At this time, the DOC 121 needs to reach a temperature (generally 250 ° C. or higher) at which the fuel can be oxidized even at a low load.

When the engine load is low, that is, when the load is low, the exhaust gas temperature at the inlet of the DOC 121 is about 100 to 150 ° C., and the fuel cannot be oxidized at the DOC 121 at such a temperature.
For this reason, in a conventional engine, control is performed to raise the exhaust gas temperature at the inlet of the DOC 121 by operating the throttle valve 105 for supplying air or the throttle valve (not shown) for exhaust. .
Such control for increasing the exhaust gas temperature, that is, control for restricting the throttle valve for supply air and the throttle valve for exhaust gas has a problem that the thermal efficiency of the engine is lowered and the fuel consumption rate of the engine is deteriorated as a result. is there.

  Note that the above-mentioned Patent Document 1 discloses an exhaust gas post-treatment that includes DOC and DPF in which fuel is injected from a fuel injection valve at a predetermined time between the downstream of the DOC and the DPF, and the temperature of the DPF is increased. The device is only disclosed, and no means for solving the above problem is shown.

  In view of the problems of the prior art, the present invention eliminates deterioration of the fuel consumption rate without performing control to throttle the throttle valve for supply and exhaust, that is, control for reducing the thermal efficiency of the engine, and particularly reduces the load on the engine. An object of the present invention is to provide an exhaust gas aftertreatment device for a diesel engine that can raise the exhaust gas temperature to normalize the DOC and DPF.

The present invention solves this problem, and exhausts exhaust gas at the exhaust turbocharger outlet of the engine through DOC (oxidation catalyst) and DPF (diesel particulate filter) to oxidize the fuel in the exhaust gas with the DOC, and the DPF In the exhaust gas aftertreatment device for a diesel engine that purifies the exhaust gas by burning PM (particulate matter) in the exhaust gas after fuel oxidation in the DOC,
A heat exchanger that stores heat in the heat receiving medium by heat exchange between the heat of the exhaust gas after passing through the DPF and the heat receiving medium is installed downstream of the DPF, and the heat received by the heating heat exchanger at the exhaust gas inlet of the DOC. A heat dissipating heat exchanger is installed to exchange heat between the heat of the medium and the exhaust gas at the exhaust gas inlet of the DOC, and the heat of the heat receiving medium is released into the exhaust gas. Between the heating heat exchanger and the heat dissipating heat exchanger, A heat medium passage is provided for sending the heat stored in the heat receiving medium by the heating heat exchanger to the heat radiating heat exchanger in a heat shield state with the outside (Claim 1).

  In such an invention, a heat medium circulation path that circulates through the heat dissipation heat exchanger from the heating heat exchanger through the heat medium passage is formed, and a transfer pump that provides a circulation force to the heat receiving medium is provided in the heat medium passage. (Claim 2).

  In the present invention, a heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of the exhaust turbocharger is connected to a heat receiving medium inlet of the heating heat exchanger, and the heating heat exchanger A discharge path for discharging the heat receiving medium after discharging heat into the exhaust gas by the heat dissipation heat exchanger through the heat medium passage through the heat dissipation heat exchanger is provided in the outside air. 3).

  In the present invention, a heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of the exhaust turbocharger is connected to a heat receiving medium inlet of the heating heat exchanger, and the heating heat exchanger A return passage is provided for connecting the heat receiving medium after releasing heat into the exhaust gas through the heat dissipation heat exchanger through the heat dissipation heat exchanger and into the exhaust gas inlet pipe of the DOC. (Claim 4).

According to the present invention, a heating heat exchanger that stores heat in the heat receiving medium by heat exchange between the heat of the exhaust gas after passing through the DPF and the heat receiving medium is installed downstream of the DPF, and the heating heat exchanger is disposed at the exhaust gas inlet of the DOC. A heat-dissipating heat exchanger for exchanging heat between the heat of the heat-receiving medium stored in the exhaust gas and the exhaust gas at the exhaust gas inlet of the DOC and releasing the heat of the heat-receiving medium into the exhaust gas; Is provided with a heat medium passage for circulating the heat stored in the heat receiving medium by the heating heat exchanger to the heat radiating heat exchanger in a heat shield state with the outside (Claim 1), in particular, the heating heat exchanger A heat pump that circulates the heat dissipation heat exchanger through the heat medium passage and a transfer pump that provides a circulation force to the heat receiving medium is provided in the heat medium passage (Claim 2). The hot gas after passing through the DPF 650 ° C.) is stored in the heat receiving medium using a heating heat exchanger that stores heat in the heat receiving medium by heat exchange between the heat of the exhaust gas and the heat receiving medium. Through the heat medium passage sent to the radiant heat exchanger, it is received by the radiant heat exchanger installed at the exhaust gas inlet of the DOC, and the radiant heat exchanger exchanges heat with the exhaust gas so that the heat of the heat receiving medium is contained in the exhaust gas. discharge.
As a result, the exhaust gas at the DOC inlet is heated by the heat of the heat receiving medium, and the heat of the high-temperature (600 to 650 ° C.) exhaust gas after passing through the DPF is efficiently obtained using the heating heat exchanger and the heat radiation heat exchanger. The exhaust gas temperature at the exhaust gas inlet of the DOC can be increased, and the amount of fuel for increasing the exhaust gas temperature can be reduced.

  This makes it easy to raise the exhaust gas temperature at the DOC inlet to a DPF operating temperature of 250 ° C. or higher at a particularly low load of the engine, that is, control to throttle the supply and exhaust throttle valves as in the prior art. Avoiding an increase in the amount of fuel for increasing the exhaust gas temperature without performing control that lowers the thermal efficiency of the engine, the effect of avoiding the deterioration of the fuel consumption rate is great.

  In the present invention, a heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of an exhaust turbocharger is connected to a heat receiving medium inlet of a heating heat exchanger similar to the above invention, and the heating heat exchange is performed. A discharge path for discharging the heat receiving medium after releasing heat into the exhaust gas by the heat dissipation heat exchanger through the heat medium passage similar to the invention through the heat medium passage to the outside air. (Claim 3), in addition to the high-temperature gas (about 600 to 650 ° C.) after passing through the DPF, in addition to the high-temperature gas (about 600 to 650 ° C.) after passing through the DPF, Since heat is applied, the temperature of the heat receiving medium in the heating heat exchanger becomes higher than in any of the above cases, and the amount of fuel for increasing the exhaust gas temperature can be reduced more than in the above case.

This makes it easier to raise the exhaust gas temperature at the DOC inlet to a DPF operating temperature of 250 ° C. or higher at a particularly low load of the engine than in any of the above cases. By avoiding an increase in the amount of fuel for increasing the exhaust gas temperature without performing the control to throttle the throttle valve, that is, the control to reduce the thermal efficiency of the engine, the effect of avoiding the deterioration of the fuel consumption rate is increased.
Further, since the gas feeding action is obtained by the speed of the heated gas branched from the exhaust gas passage at the outlet of the exhaust turbo supercharger, the transfer pump as described above becomes unnecessary, and the apparatus cost can be reduced.

  In the present invention, a heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of an exhaust turbocharger is connected to a heat receiving medium inlet of the heating heat exchanger, and the heating heat exchanger supplies the heat By providing a return passage for connecting the heat receiving medium after releasing heat into the exhaust gas through the heat dissipation heat exchanger through the medium passage to the exhaust gas inlet pipe of the DOC. (Claim 4) The heat receiving medium after releasing heat into the exhaust gas from the heating heat exchanger through the heat medium passage, through the heat medium heat exchanger, and into the exhaust gas by the heat radiation heat exchanger, the exhaust gas inlet pipe of the DOC through the return path Since the return gas is used for heating the exhaust gas of the exhaust gas inlet pipe of the DOC, the effect of avoiding an increase in the amount of fuel for increasing the exhaust gas temperature is greater than in the above case, and the fuel consumption rate is reduced. Avoiding deterioration Fruit also increased.

It is a whole block diagram of the diesel engine provided with the DOC (oxidation catalyst) and DPF (diesel particulate filter) device which concern on a reference example. It is sectional drawing of the exhaust gas aftertreatment apparatus which concerns on a reference example. It is sectional drawing of the exhaust gas post-processing apparatus which concerns on 1st Embodiment of this invention. FIG. 3 is a diagram corresponding to FIG. 1 according to a second embodiment of the present invention. FIG. 6 is a diagram corresponding to FIG. 1 according to a third embodiment of the present invention. It is a whole block diagram of the diesel engine provided with the DOC (oxidation catalyst) and DPF (diesel particulate filter) device concerning a prior art.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.

FIG. 1 shows a reference example according to the basic configuration of the present invention, and is an overall configuration diagram of a diesel engine including a DOC (oxidation catalyst) and a DPF (diesel particulate filter) device.
In FIG. 1, a diesel engine (hereinafter referred to as engine 100) includes an exhaust turbocharger 110 having an exhaust turbine 109 and a compressor 108 driven coaxially thereto, and is discharged from the compressor 108 of the supercharger 110. The air enters the air cooler 106 through the air pipe 107 and is cooled by the air cooler 106.
The air cooled by the air cooler 106 is controlled in its opening by the intake throttle valve 105, passes through the air supply pipe 104, and is sucked into the engine 100 from an air supply port provided for each cylinder.

  In the engine 100, the high-pressure fuel accumulated in the common rail (pressure accumulator) 102 is controlled in injection timing and injection amount by the common rail control device 103, and the fuel provided for each cylinder at the injection timing and injection amount. It is injected from the injection valve 101. The injected high-pressure fuel is burned by mixing with the air.

Further, an EGR (exhaust gas recirculation) pipe 116 is branched from the middle of the exhaust collecting pipe 111, and a part of the exhaust gas 120 (EGR gas) passes through the EGR pipe 116 and is cooled by the EGR cooler 115, and the EGR valve 114. Then, the flow rate is controlled and the intake throttle valve 105 of the supply pipe 104 is introduced into the downstream portion.
The combustion gas burned in the engine 100, that is, the exhaust gas 120, drives the exhaust turbine 109 of the exhaust turbo supercharger 110 through the exhaust collecting pipe 111 in which exhaust ports provided for each cylinder are gathered. After becoming the power source of the compressor 108, the exhaust gas after-treatment device 1 is entered through the exhaust pipe 112.

The above configuration is the same as that of the prior art shown in FIG.
The present invention relates to the configuration of the exhaust gas aftertreatment device 1.

FIG. 2 is a cross-sectional view of an exhaust gas aftertreatment device according to a reference example.
2 and 1, the exhaust gas that has passed through the exhaust pipe 112 enters the DOC 121 and the DPF 122 from the inlet chamber 123 of the exhaust gas aftertreatment device 1.
That is, the exhaust gas from the engine 100 enters the DOC 121 from the exhaust pipe 112 through the inlet chamber 123 of the exhaust gas aftertreatment device 1.

In the present invention, the exhaust gas aftertreatment device 1 is configured as follows.
That is, in FIGS. 2 and 1, the DPF 122 is accommodated in the case 122 a with a distance 123 a from the DOC 121.
The downstream chamber 124 downstream of the DPF 122 is provided with a heat transfer plate 3 that receives the heat of the exhaust gas after passing through the DPF 122, and the upstream chamber 123 that constitutes the exhaust gas inlet portion of the DOC 121 is provided with the heat transfer plate 3. A heat radiating plate 2 that releases the transmitted heat is provided.
The heat transfer plate 3 and the heat radiating plate 2 are connected to each other by a heat conductor 4 having heat shielding properties.

  The heat transfer plate 3 and the heat radiating plate 2 are either a perforated plate in which many holes are perforated or a heat transfer tube that is flat and capable of passing exhaust gas. Heat conductor with heat insulation, that is, a heat pipe (a refrigerant is put in a metal tube, and heat transfer and exhaust heat are performed by using the latent heat of evaporation and condensation of liquid), or the heat transfer function is cut off to the outside. It consists of a heat pipe. As described above, the heat transfer plate 3, the heat radiating plate 2, and the heat conductor 4 are configured by a very simple and low-cost apparatus.

In the reference example, the DPF 122 burns PM deposited on the DPF 122, and the combustion gas is discharged from the outlet chamber 124 to the exhaust outlet pipe 113. At this time, the exhaust gas temperature after passing through the DPF 122 is as high as 600 to 650 ° C.
In the reference example, the heat transfer plate 3 is used to heat the heat transfer plate 3 at an exhaust gas temperature of about 600 to 650 ° C., and the heat transfer plate 3 is heat having heat shielding properties with the outside. It connects to the heat sink 2 installed in the upstream chamber 123 that constitutes the exhaust gas inlet of the DOC 121 through the conductor 4, and transfers the heat of the heat transfer plate 3 from the heat conductor 4 to the heat sink 2. The heat radiating plate 2 radiates heat into the exhaust gas at the entrance of the DOC 121 to heat the exhaust gas at the entrance of the DOC 121.
Thereby, the exhaust gas temperature at the exhaust gas inlet portion of the DOC 121 can be increased using the heat of the high-temperature (600 to 650 ° C.) exhaust gas after passing through the DPF 122, and therefore the amount of fuel for increasing the exhaust gas temperature can be reduced.
In this case, the temperature of the gap 123a between the DOC 121 and the DPF 122 is about 250 to 600 ° C., which is a temperature sufficient for the operation of the DPF 122 even at a low load of the engine 100.

  This makes it possible to raise the exhaust gas temperature at the inlet of the DOC 121 to a DPF operating temperature of 250 ° C. or higher at a particularly low load of the engine 100. There is no need to perform control to throttle the valve, that is, control to reduce the thermal efficiency of the engine 100. Further, the deterioration of the fuel consumption rate can be avoided by avoiding an increase in the amount of fuel for increasing the exhaust gas temperature.

(First embodiment)
FIG. 3 is a cross-sectional view of the exhaust gas aftertreatment device according to the first embodiment.
In the first embodiment, a heating heat exchanger 6 that stores heat in the heat receiving medium by heat exchange between the heat of the exhaust gas after passing through the DPF 122 and the heat receiving medium is installed in the downstream chamber 124 of the DPF 122, and the exhaust gas inlet of the DOC 121 The heat radiating heat exchanger 7 is installed in the section (upstream chamber 123), and the heat of the heat receiving medium stored in the heating heat exchanger 6 is released into the exhaust gas at the exhaust gas inlet section (upstream chamber 123) of the DOC 121. Between the heating heat exchanger 6 and the radiant heat exchanger 7, a heat medium passage that circulates the heat stored in the heat receiving medium by the heating heat exchanger 6 to the radiant heat exchanger 7 in a heat shield state from the outside. 8 is provided.

  And in this 1st Embodiment, the heat-medium circulation path 8a which circulates through the said heat-radiation heat exchanger 7 through the said heat-medium channel | path 8 from the said heating heat exchanger 6 is formed, and the said heat-medium channel | path 8 contains the said A transfer pump 9 for providing a circulation force to the heat receiving medium is provided.

  According to the first embodiment, the heating heat exchanger 6 that stores the high-temperature gas (about 600 to 650 ° C.) after passing through the DPF 122 in the heat receiving medium by heat exchange between the heat of the exhaust gas and the heat receiving medium is used. The heat-dissipating heat exchanger is installed in the exhaust gas inlet portion of the DOC 121, that is, the upstream chamber 123 through the heat medium passage 8 that stores heat in the heat-receiving medium and sends the heat of the heat-receiving medium to the heat-dissipating heat exchanger in a heat-shielded state from the outside 7 and the heat radiating heat exchanger 7 exchanges heat with the exhaust gas to release the heat of the heat receiving medium into the exhaust gas.

  As a result, the exhaust gas at the inlet of the DOC 121 is heated by the heat of the heat receiving medium, and the heat of the high-temperature (600 to 650 ° C.) exhaust gas after passing through the DPF 122 is converted using the heating heat exchanger 6 and the heat radiation heat exchanger 7. The exhaust gas temperature at the exhaust gas inlet (upstream chamber 123) of the DOC 121 can be increased efficiently, and the amount of fuel for increasing the exhaust gas temperature can be reduced.

Accordingly, it is easier to raise the exhaust gas temperature at the inlet of the DOC 121 to the required DPF operating temperature of 250 ° C. or higher at a particularly low load of the engine than in the case of the above reference example. It is possible to avoid performing control to throttle the throttle valve 105 and the exhaust throttle valve, that is, control to reduce the thermal efficiency of the engine.
Further, since the increase in the amount of fuel for increasing the exhaust gas temperature can be avoided, the effect of avoiding the deterioration of the fuel consumption rate becomes greater than in the case of the reference example.
Other configurations are the same as those of the reference example (FIG. 2), and the same members are denoted by the same reference numerals.

(Second Embodiment)
FIG. 4 is a diagram corresponding to FIG. 1 according to the second embodiment of the present invention.
In the second embodiment, the heating pipe 11 through which the heated gas branched from the exhaust pipe 112 at the outlet of the exhaust turbine 109 of the exhaust turbocharger 110 passes is the heat receiving medium of the heating heat exchanger 6 similar to the first embodiment. Connected to the entrance.
Further, the heat exchanger 6 passes through the heat medium passage 8, passes through the heat dissipating heat exchanger 7 similar to that of the first embodiment, and the heat dissipating heat exchanger 7 exhausts the exhaust gas in the upstream chamber 123 at the exhaust gas inlet. A discharge path 11b for discharging the heat receiving medium after releasing heat into the outside air is provided.

With this configuration, in addition to the high-temperature gas (about 600 to 650 ° C.) after passing through the DPF 122, the heating gas branched from the inlet of the exhaust turbine 109 of the exhaust turbocharger 110 is supplied to the heating heat exchanger 6. The heating tube 11 to be passed is connected to the heat receiving medium inlet of the heating heat exchanger 6 similar to the first embodiment.
Therefore, in addition to the high-temperature gas (about 600 to 650 ° C.) after passing through the DPF 122, the heating pipe 11 branched from the exhaust pipe 112 at the outlet of the exhaust turbine 109 of the exhaust turbocharger 110 is supplied to the heating heat exchanger 6. Since the heat of the heating gas is applied, the temperature of the heat receiving medium in the heating heat exchanger 6 becomes higher than in the case of either the reference example or the first embodiment, and the amount of fuel for increasing the exhaust gas temperature is set to the reference example. This can be reduced more than in the first embodiment.

As a result, it is easier to raise the exhaust gas temperature at the inlet of the DOC 121 to the DPF 122 operating temperature of 250 ° C. or higher at the low load of the engine 100 than in the reference example and the first embodiment. Therefore, it is possible to avoid performing control for reducing the supply throttle valve 105 and the exhaust throttle valve, that is, control for reducing the thermal efficiency of the engine.
Moreover, since the increase in the amount of fuel for increasing the exhaust gas temperature can be avoided, the effect of avoiding the deterioration of the fuel consumption rate is greater than in the case of the reference example and the first embodiment.
Further, since the gas feed action is obtained by the heating gas speed in the heating pipe 11 branched from the exhaust pipe 112 at the outlet of the exhaust turbine 109 of the exhaust turbocharger 110, the transfer pump as in the first embodiment is obtained. No. 9 becomes unnecessary, and the apparatus cost can be reduced.
Other configurations are the same as those of the reference example (FIG. 1), and the same members are denoted by the same reference numerals.

(Third embodiment)
FIG. 5 is a block diagram corresponding to FIG. 1 according to the third embodiment of the present invention.
In the third embodiment, a return passage 13 is provided in the second embodiment to connect the heat radiation gas at the outlet of the heat radiation heat exchanger 7 to the exhaust pipe 112 of the DOC 121.
That is, the heating pipe 11 through which the heating gas branched from the inlet of the exhaust turbine 109 of the exhaust turbocharger 110 is connected to the heat receiving medium inlet of the heating heat exchanger 6, and the heating medium passage extends from the heating heat exchanger 6. 8, a return passage 13 is provided for connecting the heat receiving medium after the heat is released into the exhaust gas by the radiative heat exchanger 7 to the exhaust pipe 112 of the DOC 121.

According to the third embodiment, the heat receiving medium after releasing heat into the exhaust gas by the heat radiating heat exchanger 7 through the heat medium passage 8 from the heating heat exchanger 6 and the heat radiating heat exchanger 7 is returned. Since the return gas can be returned to the exhaust pipe 112 of the DOC 121 by the passage 13 and the return gas can be used for heating the exhaust gas of the exhaust gas inlet pipe of the DOC 121, an increase in the amount of fuel for increasing the exhaust gas temperature as compared with the second embodiment. As a result, the effect of avoiding the deterioration of the fuel consumption rate is also increased.
Other configurations are the same as those of the reference example (FIG. 1), and the same members are denoted by the same reference numerals.

  According to the present invention, the exhaust gas temperature can be reduced, particularly at a low load of the engine, without performing control for reducing the throttle valve for supply and exhaust, that is, control for reducing the thermal efficiency of the engine, and avoiding deterioration of the fuel consumption rate. It is possible to provide an exhaust gas aftertreatment device for a diesel engine that can be raised to normalize DOC and DPF.

DESCRIPTION OF SYMBOLS 1 Exhaust gas post-processing apparatus 2 Heat sink 3 Heat transfer plate 4 Heat conductor 6 Heating heat exchanger 7 Heat dissipation heat exchanger 8 Heat medium passage 8a Heat medium circulation path 9 Transfer pump 11 Heating pipe 11b Discharge path 13 Return path 100 Engine 101 Fuel injection valve 102 Common rail (pressure accumulator)
DESCRIPTION OF SYMBOLS 103 Common rail control apparatus 104 Air supply pipe 105 Supply air throttle valve 110 Exhaust turbo supercharger 111 Exhaust gas collection pipe 112 Exhaust pipe 116 EGR (exhaust gas recirculation) pipe 120 Exhaust gas 121 DOC
122 DPF

Claims (4)

The exhaust gas at the outlet of the engine turbocharger passes through the DOC and DPF, oxidizes the fuel in the exhaust gas with the DOC, and burns the PM in the exhaust gas after the fuel oxidation with the DOC with the DPF to purify the exhaust gas. In the exhaust gas aftertreatment device for diesel engines,
A heat exchanger that stores heat in the heat receiving medium by heat exchange between the heat of the exhaust gas after passing through the DPF and the heat receiving medium is installed downstream of the DPF, and the heat received by the heating heat exchanger at the exhaust gas inlet of the DOC. A heat dissipating heat exchanger is provided for exchanging heat between the heat of the medium and the exhaust gas at the exhaust gas inlet of the DOC to release the heat of the heat receiving medium into the exhaust gas, and between the heating heat exchanger and the heat dissipating heat exchanger. Is an exhaust gas aftertreatment device for a diesel engine, characterized in that a heat medium passage is provided for sending heat stored in a heat receiving medium by the heating heat exchanger to the heat radiating heat exchanger in a heat shield state from the outside.   A heat medium circulation path that circulates through the heat dissipation heat exchanger from the heating heat exchanger through the heat medium passage is formed, and a transfer pump that provides a circulation force to the heat receiving medium is provided in the heat medium passage. The exhaust gas aftertreatment device for a diesel engine according to claim 1.   A heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of the exhaust turbocharger is connected to a heat receiving medium inlet of the heating heat exchanger, and the heating heat exchanger passes through the heating medium passage to pass through the heating medium passage. The exhaust gas of a diesel engine according to claim 1, further comprising a discharge path for discharging the heat receiving medium after releasing heat into the exhaust gas through the heat dissipation heat exchanger into the exhaust gas. Post-processing device. A heating pipe for passing a heating gas branched from an exhaust gas passage to an exhaust turbine inlet of the exhaust turbocharger is connected to a heat receiving medium inlet of the heating heat exchanger, and the heating heat exchanger passes through the heating medium passage to pass through the heating medium passage. The return passage which connects the heat receiving medium after releasing heat in exhaust gas with the radiant heat exchanger through the radiant heat exchanger to the exhaust gas inlet pipe of the DOC is provided. Diesel engine exhaust gas aftertreatment device.

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