JP6472991B2 - Heat storage body disposed in exhaust pipe of internal combustion engine and exhaust gas purification system - Google Patents

Description

  The present invention relates to a heat storage body disposed in an exhaust pipe of an internal combustion engine and an exhaust gas purification system in the internal combustion engine.

  In order to comply with the regulations regarding the exhaust gas (exhaust gas) component of the internal combustion engine in recent years, various exhaust gas purification devices are arranged in the exhaust pipe path of the internal combustion engine. These exhaust gas purifiers purify exhaust gas components by chemical reaction between chemical substances such as catalyst and urea water and exhaust gas components such as NOx and PM (Particulate Matter). There is a temperature range that exhibits a good purification performance. On the other hand, the exhaust gas temperature tends to decrease as the combustion efficiency in the internal combustion engine improves. Therefore, a technique for arranging a heat storage body in the exhaust pipe path to maintain the temperature of the exhaust pipe path (for example, Patent Document 1) and a technique for heating the exhaust pipe path by a heating device (for example, Patent Document 2) are proposed. Has been.

JP 2008-75620 A JP 2012-122353 A

  However, in the technique using the heat storage body, when the temperature of the heat storage body itself is low, there is a problem that the exhaust gas temperature cannot be reduced by contacting the heat storage body and the exhaust gas cannot be purified. Further, in the technology using the heating device, when the exhaust gas temperature exhausted from the internal combustion engine is higher than the optimum temperature range of the purification device, the purification device deteriorates, and the heat energy of the exhaust gas cannot be effectively used. There has been a problem that heating of the purification device by cannot be performed efficiently.

  Therefore, there is a demand for a technique that can efficiently exhibit the performance of the purification device without depending on the temperature of the exhaust gas discharged from the internal combustion engine.

  The present invention has been made to solve the above-described problems, and can be realized as the following aspects.

  A 1st aspect provides the thermal storage body arrange | positioned at the exhaust pipe of an internal combustion engine. The heat storage body according to the first aspect is formed in a housing, a heat storage member disposed in the housing, a heating member spaced apart from the heat storage member, and the housing, A gas flow path portion through which exhaust gas exhausted from the internal combustion engine flows.

  According to the heat storage body according to the first aspect, the performance of the purification device can be exhibited efficiently without depending on the temperature of the exhaust gas discharged from the internal combustion engine.

  The heat storage body according to the first aspect may further include support means for separating the heat storage member and the heating member, and the support means is at least one of the heat storage member and the heating member. It may be a protruding portion formed on the surface. In this case, heat exchange between the heat storage member and the heating member can be suppressed or prevented.

  In the heat storage body according to the first aspect, the heating member may be included in the heat storage member, and the heating member may be included in at least a part of the heat storage member. In this case, diffusion of thermal energy released from the heating member by the heat storage member can be suppressed or prevented.

  In the heat storage body according to the first aspect, the heating member may include the heat storage member, and the heating member may cover at least a part of the heat storage member. In this case, the heat storage member can also be heated by the heating member.

  In the heat storage body according to the first aspect, at least a part of the heat storage member may include a latent heat storage body. In this case, heating at a predetermined temperature by the heat storage member can be continued for a long time.

  The heat storage body which concerns on a 1st aspect WHEREIN: The said gas flow path part is formed between the said heating member and the said thermal storage material by the said heating member and the said thermal storage material being spaced apart and arrange | positioning. It may be a separated space. In this case, the temperature of the exhaust gas can be raised by at least one of the heating member and the heat storage member, and the outside air gas can be flowed without separately providing an exhaust gas flow path portion.

  In the heat storage body according to the first aspect, the melting point of the heat storage member may be lower than the melting point of the housing. In this case, damage to the housing can be suppressed or prevented during heat storage of the heat storage member.

  In the heat storage body according to the first aspect, the heating member may extend in a direction in which the exhaust gas flows in the housing. In this case, the contact area between the exhaust gas and the heating member can be increased.

  In the heat storage body according to the first aspect, the heating member has a rod shape, and the gas flow path portion is defined by the heating member and the housing or the heat storage material disposed on an outer periphery of the heating member. It may be a channel space. In this case, the contact area between the exhaust gas and the heating member can be increased.

  The heat storage body which concerns on a 1st aspect WHEREIN: The said heating member may be provided with two or more, and the said gas flow path part may be arrange | positioned around each of the said several heating member. In this case, the contact area between the exhaust gas and the heating member can be increased, and the temperature raising efficiency of the exhaust gas can be improved.

  A 2nd aspect provides the purification system of the exhaust gas arrange | positioned at the exhaust path of an internal combustion engine. The purification system which concerns on a 2nd aspect is provided with the purification apparatus for purifying the said exhaust gas, and the any one thermal storage body which concerns on the said 1st aspect arrange | positioned in the front | former stage of the said purification apparatus.

  According to the purification system of the second aspect, the performance of the purification device can be exhibited efficiently without depending on the temperature of the exhaust gas discharged from the internal combustion engine.

It is explanatory drawing which shows roughly a vehicle provided with the exhaust gas purification system used in this embodiment. It is a perspective sectional view showing the internal configuration of the heat storage element used in this embodiment. It is sectional drawing which cut | disconnected the thermal storage body used in this embodiment by the 3-3 line in FIG. It is explanatory drawing which shows an example of the support aspect of the heater by the thermal storage member in the thermal storage body which concerns on this embodiment. It is explanatory drawing which shows notionally the time change of the exit exhaust gas temperature in the thermal storage body which concerns on this embodiment, and the conventional thermal storage body. It is a schematic diagram which shows in part a longitudinal cross-sectional view the heat storage body which concerns on a 1st modification. It is the cross-sectional view which cut | disconnected the heat storage body which concerns on a 1st modification by the 7-7 line | wire in FIG. It is a schematic diagram which shows in part a longitudinal cross-sectional view the heat storage body which concerns on a 2nd modification. It is the cross-sectional view which cut | disconnected the thermal storage body which concerns on a 2nd modification by the 9-9 line | wire in FIG.

  As an embodiment of the exhaust gas purification system and the heating element used in the exhaust gas system according to the present invention, a vehicle including a diesel engine (internal combustion engine) will be described below as an example. FIG. 1 is an explanatory diagram schematically showing a vehicle equipped with an exhaust gas purification system used in the present embodiment.

  The vehicle 500 includes a diesel engine (hereinafter referred to as “engine”) 510, four wheels 520, and an exhaust gas purification system 10. The engine 510 uses light oil as fuel, outputs driving force by the explosive combustion of the fuel, and the exhaust system is equipped with exhaust gas containing NOx (nitrogen oxide) and PM (particulate matter) accompanying the explosive combustion. It is discharged into the atmosphere through the purification system 10.

The purification system 10 includes various exhaust gas purification devices on the exhaust pipe 11. The exhaust pipe 11 is connected to the engine 510 via the manifold 11a on the engine 510 side (upstream side of the exhaust gas flow), and includes a muffler end pipe 11b on the most downstream side of the exhaust gas flow. The purification system 10 includes a diesel oxidation catalyst (DOC) 12, a diesel particulate filter (DPF) 13, a heat storage body 20, a selective catalyst reduction device (SCR) 14 and an ammonia slip diesel oxidation catalyst (NH) from the upstream side of the exhaust gas flow. ₃ DOC) 15 is provided on the exhaust pipe 11. A fuel injection device 17 may be disposed upstream of the DOC 12 on the exhaust pipe 11, and a urea water injection device 18 is disposed upstream of the SCR device 14. The term “on the exhaust pipe” in this embodiment means both the inside of the exhaust pipe and the middle of the exhaust pipe (which constitutes a part of the exhaust pipe).

The diesel oxidation catalyst 12 supports a noble metal such as platinum (Pt) or palladium (Pd) as a catalyst, and oxidizes carbon monoxide (CO) and hydrocarbon (HC), which are unburned gas components contained in the exhaust gas. Then, it is converted into carbon dioxide (CO ₂ ) and water (H ₂ O), and nitric oxide (NO) contained in the exhaust gas is oxidized to be converted into nitrogen dioxide (NO ₂ ).

The diesel particulate filter 13 is a filter that collects particulate matter (PM) contained in the exhaust gas through a fine gap in the porous ceramic. A metal catalyst such as platinum is applied to the porous surface, and the diesel particulate filter 13 has a particulate matter in an atmosphere of 250 to 300 ° C. in the presence of NO ₂ generated by the diesel oxidation catalyst 12. It is naturally regenerated by causing a chemical reaction with the catalyst and converting it to carbon dioxide (CO ₂ ) and water (H ₂ O). The diesel particulate filter 13 supplies fuel to the diesel oxidation catalyst 12 directly from the engine 510 via the fuel injection device 17 or through an exhaust stroke, and catalytically combusts fuel-derived hydrocarbons to increase the exhaust temperature. It can also be regenerated by forced regeneration in which the particulate matter collected at 450 ° C. or higher is oxidized.

The selective catalytic reduction (SCR) device 14 is a device that carries a zeolite-based catalyst or a vanadium-based catalyst and selectively reduces NOx. In the selective catalyst reduction device 14, in general, urea water is sprayed on the exhaust gas by the urea water injection device 18 at the upstream side of the selective catalyst reduction device 14, and ammonia (NH ₃₎ passes through thermal decomposition and hydrolysis reaction of urea water. ) And the NOx component in the exhaust gas is converted into nitrogen (N ₂ ) and water (H ₂ O). Therefore, the exhaust gas temperature is required to be an appropriate temperature, for example, a temperature of 200 ° C. or higher, in order to obtain ammonia from the urea water, in the upstream stage of the selective catalyst reduction device 14.

  The ammonia slip / diesel oxidation catalyst 15 supports the same catalyst as the diesel oxidation catalyst 12 and oxidizes and decomposes ammonia that has not been subjected to the reaction in the selective catalytic reduction device 14 to generate nitrogen or NOx.

  The heat storage body 20 according to the present embodiment will be described in detail below. FIG. 2 is a perspective sectional view showing the internal configuration of the heat storage body used in the present embodiment. FIG. 3 is a cross-sectional view of the heat storage body used in the present embodiment shown in FIG. 1 cut along line 3-3.

  The heat storage body 20 includes a case 21 (housing) including an outer case 211 and an inner case 212, a heater 22 as a heating member, a heat storage member 23 including a latent heat storage material 231 and a sensible heat storage material 232, a heater 22 and a heat storage member 23 An exhaust gas flow path (flow path portion) 24, a heat insulating material 25, an upstream lid 261, a downstream lid 262, and a rectifying member 263 are provided as spaces defined between the two.

  The outer case 211 and the inner case 212 are formed of stainless steel and a steel plate that has been subjected to an antioxidant treatment. The main body portions 211a and 212a have straight cylindrical shapes, and the main body portion 211a on the exhaust gas introduction side and the exhaust side, respectively. It has introduction parts 211b and 212b and discharge parts 211c and 212c having a smaller diameter than 212a. The outer case 211 and the inner case 212 are connected to each other by main body portions 211a and 212a, introduction portions 211b and 212b, and discharge portions 211c and 212c by connection portions having a substantially truncated cone shape having an inclination in a sectional view. The exhaust gas flows smoothly from 211b, 212b to the main body portions 211a, 212a and from the main body portions 211a, 212a to the discharge portions 211c, 121c.

  The introduction part 212b and the discharge part 212c of the inner case 212 are connected to the upstream cover 261 and the downstream cover 262, and the upstream cover 261 and the downstream cover 262 are connected to the introduction part 211b and the discharge part 211c of the outer case 211. By being engaged, the inner case 212 is held in the outer case 211. The heat insulating material 25 is disposed on the inner wall surface of the inner case 212 and heat conduction from the heat storage member 23 is suppressed. However, in order to further suppress heat radiation to the atmosphere, the outer case 211 and the inner case 212 A space as a heat insulating space is formed between the case 212 and the case 212.

  The upstream lid 261 and the downstream lid 262 are cylindrical members made of porous metal or porous ceramic having a plurality of flow paths (holes in front view) through which exhaust gas flows. The upstream lid 261 and the downstream lid 262 are arranged for heat insulation in the flow direction of the exhaust gas, and maintain heat in the heat storage body 20. A cylindrical rectifying member 263 whose opening is in contact with the upstream lid 261 is disposed in the introduction portion 212 b of the inner case 212. The rectifying member 263 includes a plurality of holes on the peripheral surface on the bottom surface side, and rectifies the flow of the exhaust gas so that the exhaust gas introduced from the introduction portion 212b diffuses in the radial direction of the inner case 212. As a result, the exhaust gas uniformly reaches the plurality of exhaust gas passages 24 between the heater 22 and the heat storage member 23. When the exhaust gas temperature is higher than the temperature of the heat storage member 23, the heat storage member 23 absorbs the heat energy of the exhaust gas to increase the temperature of the heat storage member 23 and maintain (heat storage). When the temperature is lower than the temperature of the member 23, the stored heat energy is released and the exhaust gas is heated. That is, heat exchange based on the temperature difference between the exhaust gas and the heat storage member 23 is performed.

  FIG. 4 is an explanatory diagram showing an example of a support mode of the heater by the heat storage member inside the heat storage body according to the present embodiment. The heater 22 has a rod-like outer shape extending in the flow direction of the exhaust gas in the case 21. For example, in the present embodiment, eight heaters 22 are used. By providing a plurality of heaters 22, the contact area between the heaters 22 and the exhaust gas can be increased, and the temperature rise efficiency of the exhaust gas by the heaters 22 can be improved. The heater used in this embodiment is, for example, a cartridge heater in which two lead wires extending from an electrode connected to a heating element arranged inside a stainless steel housing extend from one end. Although two lead wires are not shown in FIG. 2 for ease of explanation, the lead wires of the heaters 22 are connected to the case 21 through lead wire extraction holes formed at arbitrary positions on the side surfaces of the case 21. Is connected to an external heater controller (not shown), and the heating temperature by energization is controlled. In the present embodiment, the heater 22 is used to increase the exhaust gas temperature to a predetermined temperature or to store heat when the exhaust gas temperature is lower than a predetermined temperature and the temperature of the heat storage member 23 is lower than the predetermined temperature. Used to raise the temperature of the member 23 to a predetermined temperature. Here, the determination as to whether or not the temperature of the heat storage member 23 is lower than a predetermined temperature is a temperature sensor provided inside the heat storage body 20 or an exhaust gas temperature sensor provided outside the heat storage body 20 on the downstream side. Alternatively, it may be determined by a temperature sensor, or may be determined uniformly by an elapsed time immediately after the engine 510 is started or after the engine 510 is started.

Of the heat storage member 23, the latent heat storage material 231 is a solid phase storage material at normal temperature and phase transitions to the liquid phase by the heat of exhaust gas. For example, aluminum latent heat storage material, nitrates such as LiNO ₂ and NaNO ₂ It is possible to use a molten salt of a chloride, a molten salt of a chloride such as LiCl or NaCl, or a molten salt of an alkali metal carbonate such as LiCO ₂ or K ₂ CO ₂ . The desirable melting point of the latent heat storage material 231 in this embodiment is 200 ° C. to 600 ° C., which is lower than the melting point of the case 21. As the sensible heat storage material 232, for example, stainless steel, mild steel, a ceramic material, a sintered body of metal powder, a metal honeycomb, or the like can be used.

  The sensible heat storage material 232 includes a heater storage space 232a for storing each heater 22 independently, and a substantially radial latent heat storage material storage space in a cross-sectional view for storing the latent heat storage material 231. Since the latent heat storage material 231 has a larger volume in the liquid phase than in the solid phase, the latent heat storage material accommodating space has a capacity that matches the volume of the latent heat storage material 231 in the liquid phase. doing. Moreover, since the shape of the latent heat storage material accommodation space is the same as that of the latent heat storage material 231 in a liquid phase state, the shape of the latent heat storage material 231 is indicated by the reference numeral for the latent heat storage material 231 and individual reference numerals are omitted. It is desirable that the inner wall of the latent heat storage material accommodation space of the sensible heat storage material 232 is subjected to a sealing process in order to prevent / suppress impregnation of the latent heat storage material 231. Both end surfaces of the latent heat storage material accommodation space in the sensible heat storage material 232 are sealed by a heat storage member lid 231a. The heat storage member lid 231 a is formed of the same material as the sensible heat storage material 232.

  The heater housing space 232a has a circular tubular portion 232b along the outer periphery of the heater 22 and six radial spaces 24 formed extending from the circular tubular portion in the outer shape in a cross-sectional view. The heater accommodating space 232a may be a through space penetrating in the longitudinal direction or a non-penetrating space that does not penetrate. In a cross-sectional view, the radial (gear-shaped) space 24 penetrates the heat storage member 23 in the longitudinal direction to form an exhaust gas passage 24. That is, in the present embodiment, the heater 22 and the heat storage body 20 are spaced apart from each other, and the exhaust gas introduced into the heat storage body 20 from the introduction portions 211b and 212b flows through the exhaust gas passage 24 and is discharged. The heat is discharged from the portions 211c and 212c to the outside of the heat storage body 20. The fact that the heater 22 and the heat storage member 23 are arranged apart from each other means that substantial heat conduction due to contact does not occur between the heater 22 and the heat storage member 23, and the heater 22 and the heat storage member 23 are arranged. Means an arrangement relationship in which heat exchange can be performed with the exhaust gas, and point contact, partial line contact, and the like may exist between the heater 22 and the heat storage member 23. In the present embodiment, of the heater housing space 232a, the tubular portion 232b is provided with a protruding portion 27 as a support means for supporting the heater 22 separately from the sensible heat storage material 232 in the heater housing space 232a. Is formed. For example, as shown in FIG. 4, the protruding portions 27 may be formed two by two in the vicinity of both ends of the circular tubular portion 232b, or may be further provided in the intermediate region of the circular tubular portion 232b. good. In any case, the protrusion 27 may be formed so that the heater 22 can be supported while being separated from the sensible heat storage material 232 in the heater housing space 232a. The protrusion 27 may be formed as a part of the inner periphery of the sensible heat storage material 232, or may be formed as a part of the outer periphery of the heater 22.

  As shown in FIG. 3, the latent heat storage material 231 includes a central portion and eight extending portions 231 b extending radially from the central portion (in other words, the sensible heat storage material 232 is radial from the central portion and the central portion. A latent heat storage material containing space including eight extending portions 231b extending in the middle). Each extending portion 231b is disposed between each heater accommodating space 232a (exhaust gas passage 24), absorbs thermal energy from the exhaust gas flowing through the exhaust gas passage 24, releases thermal energy to the exhaust gas, and from the heater 22. The efficiency of absorption of thermal energy is improved.

  The heat insulating material 25 is arrange | positioned over the outer peripheral surface of the sensible heat storage material 232, for example, is comprised by the sheet | seat material made from a ceramic, a cylindrical hard material, etc. By providing the heat insulating material 25, the heat conduction amount to the metal inner case 212 can be suppressed, and the heat retention efficiency of the heat storage body 20 can be maintained at a desired level.

  Hereinafter, the operation and technical advantages of the heat storage body 20 according to the present embodiment and the exhaust gas purification system 10 including the heat storage body 20 will be described. FIG. 5 is an explanatory diagram conceptually showing temporal changes in the outlet exhaust gas temperature in the heat storage body according to the present embodiment and the conventional heat storage body. In FIG. 5, the characteristic line L1 conceptually shows the temporal change of the outlet exhaust gas temperature in the heat storage body according to the present embodiment, and the characteristic line L2 does not have a conventional heat storage body (heat storage material) and heater but only the exhaust pipe. , Conceptually shows the temporal change of the outlet exhaust gas temperature, and the characteristic line L3 conceptually shows the temporal change of the outlet exhaust gas temperature in the conventional heat storage body. In addition, the conventional heat storage body regarding the characteristic line L3 means the heat storage body which has only a sensible heat storage material and does not have a heater.

  In the time region T1 (at the time of introduction of low-temperature exhaust gas) immediately after start-up, the exhaust gas temperature is 200 ° C. or less, and when the cold time is long, the temperature of the heat storage body is also reduced. As a result, in the conventional exhaust pipe only (L2) and the conventional heat storage body only (L3), the rise in the outlet temperature is slow, and the conversion from urea water to ammonia is properly realized in the subsequent SCR device over the time domain T1. The appropriate operating temperature Te1 (for example, 200 ° C.) cannot be reached. Moreover, in the conventional heat storage body (L3), since the heat storage body absorbs the thermal energy of the exhaust gas, the rise in the outlet temperature is further reduced compared to the conventional exhaust pipe (L2) that does not have the heat storage body. As a result, the NOx processing may not be performed sufficiently. On the other hand, in the present embodiment (L1), when the engine is started, the heater 22 is energized to perform heating by the heater 22 (H1). As a result, the outlet temperature quickly reaches the appropriate operating temperature Te1, and the selective catalytic reduction device (SCR) 14 can be appropriately operated. As a result, in the selective catalyst reduction device (SCR) 14, the conversion from urea water to ammonia is appropriately realized, and NOx can be processed immediately after the engine is started.

  In the time region T2 (when exhaust gas fluctuates) during vehicle operation, the introduced exhaust gas temperature varies between a low temperature (for example, 100 ° C.) and a high temperature (for example, 600 ° C.). In the conventional exhaust pipe (L2), when the exhaust gas temperature increases, the temperature immediately increases as the temperature increases, and when the exhaust gas temperature decreases, the temperature immediately decreases. That is, the heat energy at the time when the exhaust gas temperature rises cannot be sufficiently absorbed, and the heat energy cannot be sufficiently kept at the time when the exhaust gas temperature falls. Therefore, for example, the outlet temperature fluctuates between the SCR temperature shortage region and the SCR optimum temperature region with the proper operating temperature Te1 as a boundary. As a result, the NOx processing in the subsequent SCR device becomes unstable, and the NOx processing may not be performed sufficiently. Further, although the conventional heat storage body (L3) shows the effect of reducing the temperature fluctuation, when the exhaust gas temperature is lowered, the proper operating temperature Te1 at which the conversion from urea water to ammonia is appropriately realized in the subsequent SCR device. (For example, 200 ° C.) may not be reached (period indicated by T2 ′ in the figure).

  On the other hand, in this embodiment (L1), since the heat storage body 20 is equipped with the latent heat storage material 231, even if the introduction exhaust gas temperature rises, until the phase change is completed, the latent heat storage material 231 temperature is The heat energy that the exhaust gas does not increase is used for heat storage of the latent heat storage material 231 (H2), and the temperature increase of the heat storage body 20 is moderate. On the other hand, even when the temperature of the introduced exhaust gas decreases, the temperature of the latent heat storage material 231 does not decrease until the phase change is completed, and after the decrease, the temperature of the heat storage body 20 decreases due to the heating (H1) by the heater 22. Is moderate. That is, the exhaust gas temperature discharged from the heat storage body 20 can be leveled by the cooperation of the heat storage body 20 (latent heat storage material 231) and the heater 22. Therefore, the outlet temperature is maintained in the SCR optimum temperature region higher than the appropriate operating temperature Te1, and as a result, the NOx processing in the subsequent SCR device is stabilized and the NOx processing can be sufficiently performed. In the time region T2 during vehicle operation (when the exhaust gas fluctuates), energization of the heater 22 is executed when the introduced exhaust gas temperature is lower than the predetermined temperature, and when the introduced exhaust gas temperature is higher than the predetermined temperature. Is stopped. In the conventional heat accumulator (L3), the appropriate operating temperature Te1 of the SCR device was not reached in the period indicated by T2 ′ in the figure, but it is set to a temperature higher than the appropriate operating temperature Te1 by heating by the heater 22. it can. The predetermined temperature may be a predetermined temperature. In this case, hysteresis may be set to the predetermined temperature used for determination of execution and stop of energization. That is, a predetermined temperature higher or lower than the predetermined temperature may be set for the temperature change direction in which the thermal response is inferior. Further, instead of or in addition to the predetermined temperature, the energization may be executed and stopped when the temperature change rate exceeds or falls below the predetermined change rate. In this case, the temperature fluctuation across the predetermined temperature can be made gentler.

  In the time region T3 (when high-temperature exhaust gas is introduced) during vehicle operation, the introduced exhaust gas temperature is high (for example, 600 ° C. or higher). The generation of the high-temperature exhaust gas occurs, for example, when the regeneration process is executed in the diesel particulate filter (DPF) 13 in the front stage of the heat storage body 20, and is continued for 20 minutes, for example. In the conventional exhaust pipe (L2), when the exhaust gas temperature becomes high, the heat energy cannot be sufficiently absorbed and the temperature rises as it is, and the outlet temperature deteriorates the SCR device. Had reached the area. As a result, there is a possibility of causing thermal damage to the subsequent SCR device. Although the heat storage body (L3) has an effect of suppressing the temperature rise, since the sensible heat storage material is used as the heat storage material, the heat energy from the exhaust gas cannot be sufficiently absorbed, and the SCR deterioration temperature region May lead to

  On the other hand, in this embodiment (L1), since the heat storage body 20 is equipped with the latent heat storage material 231, even if the introduction exhaust gas temperature rises, until the phase change is completed, the latent heat storage material 231 temperature is The heat energy that the exhaust gas does not increase is used for heat storage of the latent heat storage material 231 (H2), and the temperature increase of the heat storage body 20 is moderate. As a result, even at the time of DPF regeneration, the outlet temperature does not reach the SCR deterioration appropriate temperature region that causes deterioration of the SCR device, and as a result, does not cause thermal damage to the subsequent SCR device.

  As described above, according to the heat storage body 20 according to the present embodiment, the heater 22 and the heat storage member 23 are separated from each other, and the space 24 defined by the heater 22 and the heat storage member 23 is an exhaust gas flow path. 24 functions. Therefore, even when the temperature of the heat storage member 23 is low, the exhaust gas introduced into the heat storage body 20 can be quickly heated by the heater 22. When the heater 22 and the heat storage member 23 are in contact, when the temperature of the heat storage member 23 is low, the heat energy generated by the heater 22 is absorbed by the heat storage member 23 (used to heat the heat storage member 23). The exhaust gas temperature cannot be increased efficiently and quickly.

  In the present embodiment, the exhaust gas passage 24 is disposed between the heater 22 and the heat storage member 23. Therefore, the exhaust gas, the heater 22 and the heat storage member 23 are in direct contact with each other and can exchange heat with the exhaust gas independently (without being affected by the mutual heat capacity). As a result, when the exhaust gas temperature is low, the exhaust gas temperature can be efficiently increased by at least one of the heater 22 and the heat storage member 23, and when the exhaust gas temperature is high, the exhaust gas is The thermal energy it has can be efficiently absorbed and stored.

  Since the heat storage member 23 in the present embodiment includes the latent heat storage material 231, the temperature change of the exhaust gas discharged from the heat storage body 20 is suppressed, or the temperature of the exhaust gas is prevented from deviating from the predetermined temperature range. Or it can be prevented. That is, by using the latent heat storage material 231 whose melting point corresponds to the intermediate temperature in the predetermined temperature range as the latent heat storage material 231, the temperature of the heat storage member 23 can be maintained near the intermediate temperature for a relatively long period. As a result, when the introduced exhaust gas is heated and when it is heated by the introduced exhaust gas, the temperature of the exhaust gas discharged from the heat storage body 20 can be set near the intermediate temperature. In addition, since the heat storage body 20 according to the present embodiment includes the heater 22, even when the temperature of the heat storage member 23 is low, such as immediately after the engine is started, the introduced exhaust gas is heated to quickly reach a predetermined temperature. A range of exhaust gases can be discharged. Therefore, when an exhaust gas purifying device that functions in a predetermined temperature range is provided in the subsequent stage (downstream side) of the heat accumulator 20, the operation of the purifying device under a wide range of conditions without depending on the operating state of the engine 510. It is possible to improve the operation ratio of the purification device.

  The exhaust gas purification system 10 according to the present embodiment includes a heat storage body 20 according to the present embodiment in the preceding stage of the SCR device 14. The DPF 13 is provided in the front stage of the heat accumulator 20, and during the regeneration process of the DPF 13, the exhaust gas temperature discharged from the DPF 13 is about 600 ° C., and such a high temperature exhaust gas is thermally deteriorated in the catalyst of the SCR device 14. There is a risk of Since the exhaust gas purification system 10 according to the present embodiment includes the heat storage body 20 between the DPF 13 and the SCR device 14, the exhaust gas having a temperature exceeding 600 ° C. is discharged from the DPF 13 as described above. Thus, the exhaust gas whose temperature has been lowered to about 400 ° C., for example, can be discharged toward the SCR device 14 by the heat storage body 20. As a result, thermal deterioration of the catalyst in the SCR device 14 can be suppressed or prevented.

  Since the exhaust gas purification system 10 according to the present embodiment includes the heat storage body 20 at the front stage of the SCR device 14, the exhaust gas having a temperature suitable for NOx purification is constantly supplied to the SCR device 14. As a result, the SCR device 14 can perform NOx purification even under conditions in which NOx purification could not be performed conventionally due to a decrease in exhaust gas temperature, further reducing the amount of NOx emitted to the atmosphere. Can be reduced. Further, the exhaust gas temperature increasing process by fuel combustion, which has been conventionally performed in the DOC 12 and DPF 13 for increasing the exhaust gas temperature, is unnecessary, and the amount of fuel consumed can be reduced regardless of traveling. .

Variation:
The heat storage body 20 according to the present embodiment may adopt the following configuration in addition to the above configuration. FIG. 6 is a schematic view showing a part of the heat storage body 20a according to the first modification in a longitudinal sectional view. FIG. 7 is a cross-sectional view of the heat storage body 20a according to the first modification, cut along line 7-7. FIG. 8 is a schematic view showing a part of the heat storage body 20b according to the second modification in a longitudinal sectional view. FIG. 9 is a cross-sectional view of the heat storage body 20b according to the second modification taken along line 9-9.

(1) A heat storage body 20a according to the first modification shown in FIGS. 6 and 7 has a plurality of columnar heaters 22 arranged along the central axis of a cylindrical case 21, and each heater 22 is a heat storage member 23. The structure is covered with at least a part of. Although FIG. 6 shows an example including two heaters 22, the number of heaters 22 may be one or three or more. When a plurality of heaters 22 are provided, the contact area between the heater 22 and the exhaust gas can be increased, and the temperature rise efficiency of the exhaust gas by the heater 22 can be improved. Moreover, as shown in the said embodiment, multiple pieces may be arrange | positioned at radial direction. Furthermore, the heaters 22 are arranged only on the exhaust gas discharge side or the exhaust gas discharge side of the heat storage body 20a, or are arranged in large numbers on the exhaust gas discharge side or the exhaust gas discharge side, realizing high exhaust gas temperature discharge. You may do it. In this case, the exhaust gas can be efficiently heated while keeping the number of heaters 22 low.

  The heaters 22 and the heat storage member 23 are spaced apart from each other, and a space 24 that functions as an exhaust gas flow path is defined between the outer peripheral surface of each heater 22 and the inner peripheral surface of the heat storage member 23. Yes. Each heater 22 is point-supported by a heat storage member 23 via a projecting portion 27 as a support means, whereby a space 24 is defined between the outer peripheral surface of each heater 22 and the inner peripheral surface of the heat storage member 23. . Also in the heat storage body 20a according to the first modified example, the heaters 22 and the heat storage members 23 are arranged apart from each other. Therefore, even when the heat storage members 23 are at a low temperature, the exhaust gas is quickly discharged by the heaters 22. It becomes possible to heat, and when the heat storage member 23 is at a high temperature, the heat storage member 23 can heat the exhaust gas. Further, when the exhaust gas is hot, the heat storage member 23 is heated by the exhaust gas and stores heat obtained from the exhaust gas. In addition, when the latent heat storage material is included in the heat storage member 23, the exhaust gas temperature discharged can be maintained within a predetermined temperature range.

(2) In the heat storage body 20b according to the second modification shown in FIGS. 8 and 9, a columnar heat storage member 23 is disposed along the central axis of the cylindrical case 21, and a plurality of the heat storage members 23 are disposed around the heat storage member 23. The heater 22 covers the structure. That is, each heater 22 covers at least a part of the heat storage member 23. Although FIG. 8 shows an example in which two heaters 22 are provided, the number of heaters 22 may be one or three or more. When a plurality of heaters 22 are provided, the contact area between the heater 22 and the exhaust gas can be increased, and the temperature rise efficiency of the exhaust gas by the heater 22 can be improved. In addition, the heater 22 may be plate-shaped (cylindrical) and may cover the entire circumference of the heat storage member 23, or may be rod-shaped and disposed at a part of the periphery of the heat storage member 23. Furthermore, the heaters 22 are arranged only on the exhaust gas exhaust side or the exhaust gas exhaust side of the heat storage body 20b, or many heaters 22 are arranged on the exhaust gas exhaust side or the exhaust gas exhaust side, realizing high exhaust gas temperature exhaust. You may do it. In this case, the exhaust gas can be efficiently heated while keeping the number of heaters 22 low.

  Each heater 22 is disposed along the inner peripheral surface of the case 21, and each heater 22 and the heat storage member 23 are disposed apart from each other. It can be said that the heat storage member 23 partially includes the latent heat storage material 231 in the sensible heat storage material 232, and the heat storage member 23 includes the latent heat storage material 231 at least partially. A space 24 that functions as an exhaust gas flow path is defined between the inner peripheral surface of the heater 22 and the outer peripheral surface of the heat storage member 23. The heat storage member 23 is point-supported by the heater 22 via a protruding portion 27 as a support means, whereby a space 24 is defined between the inner peripheral surface of the heater 22 and the outer peripheral surface of the heat storage member 23. Also in the heat storage body 20b according to the second modified example, since the heater 22 and the heat storage member 23 are spaced apart from each other, the heater 22 quickly heats the exhaust gas even when the heat storage member 23 is at a low temperature. In addition, when the heat storage member 23 is hot, the heat storage member 23 can heat the exhaust gas. Further, when the exhaust gas is hot, the heat storage member 23 is heated by the exhaust gas and stores heat obtained from the exhaust gas. Further, since the heat storage member 23 includes the latent heat storage material 231, the exhaust gas temperature discharged can be maintained within a predetermined temperature range.

(3) The exhaust gas purification system 10 according to the present embodiment may adopt the following configuration in addition to the above configuration. In the exhaust gas purification system 10 according to the above-described embodiment, the heat storage body 20 is disposed between the DPF 13 and the SCR device 14, but the heat storage body 20 may be disposed in front of the DPF 13. In this case, it is possible to maintain the exhaust gas temperature introduced into the DPF 13 at a high temperature, and it is expected that the regeneration process will be periodically performed spontaneously without the forced regeneration process with fuel injection. obtain. As a result, it is not necessary to consume fuel for the regeneration process, and the fuel efficiency of the vehicle can be improved.

  The purification device in the present specification is not limited to a so-called chemical reaction purification catalyst that converts a specific component (substance) in exhaust gas into a non-hazardous component (substance) by a catalyst. A filter-type purification device that collects components is also included. Even in the filter type purification apparatus, there may be an appropriate temperature range for appropriately performing the regeneration operation. If the heat storage body 20 according to this embodiment is used, the exhaust gas temperature introduced into the filter type purification apparatus can be set. The filter-type purifying device can be maintained in an appropriate temperature range, and can exhibit the expected performance under a wide range of conditions without depending on the operating condition of the engine 510. Therefore, the heat storage body 20 according to the present embodiment may be used in the previous stage of any purification device as long as the purification device exhibits performance by introducing exhaust gas in a predetermined temperature range. By being used in the previous stage of the purification device, the performance of the purification device can be exhibited under a wide range of conditions.

(4) In the above embodiment, the diesel engine 510 has been described as an example. However, the heat storage body 20 according to the present embodiment is disposed in the exhaust path of the gasoline engine, and constitutes an exhaust gas purification system for the gasoline engine. May be. The exhaust gas temperature of a gasoline engine is higher than the exhaust gas temperature of a diesel engine, but in order to achieve sufficient exhaust gas purification from the start of the engine, the catalyst temperature is set to a temperature range where the catalyst exhibits its intended performance. Various attempts have been made to raise it. For example, an early warming-up of the catalyst has been attempted by arranging a three-way catalyst, which is generally used as a purification device for a gasoline engine, immediately below the exhaust manifold. However, when the arrangement position of the catalyst is determined depending on the heat distribution of the exhaust gas temperature, the arrangement position of the catalyst has no degree of freedom, and the design around the engine has no degree of freedom. On the other hand, if the heat storage body 20 according to the present embodiment is applied, it is possible to realize early warm-up regardless of the arrangement position of the three-way catalyst, and there is an advantage that the degree of freedom in vehicle design is increased. .

(5) In the above embodiment, the space 24 between the heat storage member 23 and the heater 22 is used as an exhaust gas flow path, but the exhaust gas contacts the heat storage member 23 and the heater 22 separately. An exhaust gas flow path may be provided. Even in this case, as long as the heat storage member 23 and the heater 22 are spaced apart from each other, the heater 22 can heat the exhaust gas without taking heat energy (amount of heat) by the heat storage member 23. Thus, the advantages obtained by the present embodiment can be obtained. The exhaust gas is also heated by the heat storage member 23 or heats the heat storage member 23. In addition, the space 24 between the heat storage member 23 and the heater 22 is used as an exhaust gas flow path, but the exhaust gas flow path may have a metal honeycomb structure.

(6) In the said embodiment, although the thermal storage body 20 provided with the one thermal storage member 23 is used, the thermal storage body 20 may have the some independent thermal storage member 23. FIG. In this case, the temperature distribution of the exhaust gas in the heat storage body 20 can be made uniform by diffusion and mixing of the exhaust gas temperature between the heat storage members 23.

(7) In the said embodiment, although the thermal storage body 20 has a linear cylinder shape (cylindrical) shape, it is a redundant shape which was bent back several times from the introduction parts 211b and 212b to the discharge parts 211c and 212c. It may have a shape. Moreover, in the said embodiment, although the exhaust gas purification system 10 extended linearly is demonstrated as an example as a mounting system of the thermal storage body 20, as for the thermal storage body 20, one part structure or piping has another structure. Alternatively, it may be applied to a purification system that is arranged in a direction intersecting with the piping and formed in a folded shape. For example, it is applied to a purification system having a folded shape having a parallel part arranged parallel to the ground when mounted on the vehicle and a crossing part intersecting the parallel part, and having a reduced length in the flow direction of exhaust gas. Also good. The intersecting portion may be a vertical portion perpendicular to the ground, and may be a purification system having a bulk in the vertical direction. In this case, the heat storage body 20 may be disposed at either the parallel portion or the intersecting portion.

  As mentioned above, although this invention was demonstrated based on the Example and the modification, Embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the spirit and scope of the claims, and equivalents thereof are included in the present invention. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Purification system 11 ... Exhaust pipe 11a ... Manifold 11b ... Muffler end pipe 12 ... Diesel oxidation catalyst 13 ... Diesel particulate filter 14 ... Selective catalyst reduction device 15 ... Diesel oxidation catalyst 17 ... Fuel injection device 18 ... Urea water injection device 20 ... Thermal storage body 20a ... Thermal storage body 20b ... Thermal storage body 21 ... Case 211 ... Outer case 211a ... Main body part 211b ... Introduction part 211c ... Discharge part 212 ... Inner case 212a ... Main body part 212b ... Introduction part 212c ... Discharge part 22 ... Heater 23 ... Heat storage member 231 ... Latent heat storage material 231a ... Heat storage member lid 232 ... Sensible heat storage material 232a ... Heater housing space 232b ... Cylindrical part 24 ... Space, exhaust gas flow path 25 ... Heat insulation material 27 ... Projection part 261 ... Upstream side cover 262: Downstream lid 263: Rectifying member 500 ... Vehicle 510 ... De Over diesel engine 520 ... wheel

Claims (14)

A heat storage body disposed in an exhaust pipe of an internal combustion engine,
A housing;
A heat storage member disposed within the housing;
A heating member that is disposed opposite to the heat storage member;
A gas flow path formed in the housing through which an exhaust gas exhausted from the internal combustion engine flows , wherein the heating member and the heat storage member are disposed apart from each other; A gas flow path portion which is a separated space formed between the heat storage member, and
A heat storage body comprising The heat storage body according to claim 1, further comprising:
A support means for separating the heat storage member and the heating member;
Thermal storage body. The heat storage body according to claim 2,
The support means is a protruding portion formed on at least one of the heat storage member and the heating member.
Thermal storage body. In the thermal storage body as described in any one of Claim 1 to 3,
The heating member is a heat storage body included in the heat storage member. The heat storage body according to claim 4,
The heating member is a heat storage body included in at least a part of the heat storage member. In the thermal storage body as described in any one of Claim 1 to 3,
The heating member is a heat storage body including the heat storage member. The heat storage body according to claim 6,
The heating member is a heat storage body covering at least a part of the heat storage member. In the thermal storage body as described in any one of Claim 1 to 7,
A heat storage body, wherein a latent heat storage body is included in at least a part of the heat storage member. In the thermal storage body as described in any one of Claim 1 to 8 ,
The heat storage member has a melting point lower than the melting point of the housing. In the thermal storage body as described in any one of Claim 1 to 9 ,
The heating member is a heat storage body that extends in a direction in which the exhaust gas flows in the housing. The heat storage body according to claim 10 ,
The heating member is rod-shaped,
The gas flow path section is a heat storage body that is a flow path space defined by the heating member and the housing or the heat storage member disposed on the outer periphery of the heating member. In the thermal storage body as described in any one of Claim 1 to 11 ,
A heat accumulator comprising a plurality of the heating members. The heat storage body according to claim 12 ,
The said gas flow path part is a thermal storage body arrange | positioned around each of the said several heating member. An exhaust gas purification system disposed in an exhaust path of an internal combustion engine,
A purification device for purifying the exhaust gas;
A regenerator which is described in any one of claims 1 to 13 disposed in front of the cleaning device,
Purification system comprising.

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