JP4715883B2 - Exhaust treatment device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust treatment device in which a catalyst is disposed in an exhaust passage of an internal combustion engine, and more particularly to an exhaust treatment device for an internal combustion engine provided with means for recovering or discarding heat of exhaust gas.

  A catalyst is provided in an exhaust pipe of an internal combustion engine, and the exhaust gas is purified by the action of the catalyst. There is also known an apparatus having a means for heating a catalyst for improving purification in the cold state, and promoting the activation by raising the temperature of the catalyst. For example, in Patent Document 1, in a vehicle including a power source including an internal combustion engine, a gas purification catalyst is provided in an exhaust pipe, and a combustion gas passage from a combustion heater used for engine warm-up or the like is connected upstream thereof. Thus, a control device that raises the temperature at start-up has been proposed.

  However, the control device described in Patent Document 1 has a drawback in that heat utilization efficiency is poor because heat that has passed through the catalyst is discarded. On the other hand, by employing a heat recovery device as described in Patent Document 2, it is considered to use the heat of the exhaust.

Patent Document 2 discloses an exhaust heat recovery apparatus in which a heat exchange path and a medium path are concentrically arranged on the outer periphery of a bypass path, and a switching valve for switching the exhaust gas path between the bypass path and the heat exchange path is provided. Is disclosed. This device uses the recovered heat to warm up the internal combustion engine by guiding exhaust gas to the heat exchange path when the vehicle is cold, and exhausts the exhaust gas to the bypass path after warming up. .
JP 2002-47922 A JP 2008-25557 A

  However, the heat recovery apparatus described in Patent Document 2 has a complicated configuration for forming a plurality of paths and a configuration for changing the flow of exhaust gas. In addition, since the heat medium may be deteriorated under a high temperature condition, it is necessary to change the flow of the exhaust gas in order to prevent the deterioration, and a switching valve is provided. However, the switching valve has a configuration in which a valve body that is rotatable about a valve shaft opens and closes the opening end of the bypass pipe, and has a drawback that it is not reliable in a high temperature and corrosive environment.

  Therefore, the present invention provides an exhaust treatment apparatus having a means for heating a catalyst in an exhaust passage, making it possible to effectively implement the temperature rise control of the catalyst by efficiently using the generated heat, and further use it. The purpose of the present invention is to realize a highly efficient and highly reliable exhaust treatment apparatus that can suppress deterioration of the heat medium, improve durability in high temperature and corrosive environments.

According to the first aspect of the present invention, an exhaust treatment apparatus for an internal combustion engine comprising a catalyst provided in an exhaust passage of the internal combustion engine, a heating means for heating the catalyst, and a heat recovery means for recovering the heat of the exhaust gas. In
The heat recovery means includes a pair of heat transfer means installed respectively upstream and downstream of the catalyst, a heat recovery flow path connecting the pair of heat transfer means, and a heat medium provided in the heat recovery flow path Have transport means,
Control means is provided for controlling the operation of the heating means and the heat medium transport means and the direction of heat recovery during the operation of the heat medium transport means in accordance with the temperature of the exhaust gas discharged into the exhaust passage.

  In the above configuration, when the temperature of the exhaust gas is low, the heat recovery unit operates the heating unit and returns the heat of the exhaust gas downstream of the catalyst to the upstream side by the heat medium transport unit to promote the temperature rise of the catalyst. When the temperature of the exhaust gas is high, the temperature of the catalyst is prevented from excessively rising by discharging the heat of the exhaust gas upstream of the catalyst to the downstream side. Therefore, exhaust heat can be efficiently reused, catalyst deterioration can be prevented, and temperature rise control can be performed effectively, so that an exhaust treatment apparatus with high efficiency and excellent reliability can be realized.

  According to a second aspect of the present invention, in the first aspect of the invention, the control means turns on the heating means and turns on the heat medium conveying means when the temperature of the exhaust gas is lower than the activation temperature of the catalyst. Thus, the heat recovered by the heat transfer means downstream of the catalyst is returned to the upstream heat transfer means. On the other hand, in the invention according to claim 3, when the temperature of the exhaust gas is equal to or higher than the deterioration temperature of the catalyst, the heating means is turned off, the heat medium conveying means is turned on, and the heat transfer means upstream of the catalyst. The heat recovered in (1) is discarded through the downstream heat transfer means, and the temperature rise and cooling of the catalyst is controlled.

  Specifically, the heating means is switched on and off according to the exhaust temperature, and the movement of the heat recovered by the heating medium is controlled to effectively heat or cool the catalyst. Temperature control can be implemented.

  According to a fourth aspect of the invention, in the first, second, or third aspect of the invention, the control means turns off the heating means when the temperature of the exhaust gas is equal to or higher than the activation temperature of the catalyst.

  Specifically, when the catalyst temperature can be maintained at the activation temperature or higher with the heat of the exhaust gas, energy loss is eliminated and more effective temperature control can be realized by stopping the operation of the heating means. .

  According to a fifth aspect of the present invention, in the first to fourth aspects of the invention, the heat recovery flow path includes a pair of heat medium flow paths that are respectively connected at both ends to the pair of heat transfer means. The heat medium flow path and the pair of heat transfer means form a heat medium circulation path to move the heat of the exhaust gas from one of the heat transfer means to the other.

  Specifically, a pair of heat transfer means are connected by a pair of heat medium flow paths, and the heat medium circulates through the heat recovery passage, so that the heat recovered on the one hand can be easily moved to the other. Therefore, heat recovery and reuse can be performed efficiently.

  According to a sixth aspect of the present invention, in the exhaust gas processing apparatus for an internal combustion engine according to the fifth aspect, the heat transfer means is disposed in contact with the outer periphery of the exhaust passage and communicates with the pair of heat medium flow paths. A heat transfer chamber having an inlet and an outlet is provided, and a heat medium passing through the heat transfer chamber exchanges heat with the exhaust in the exhaust passage.

  Specifically, when the heat transfer means is formed so as to surround the exhaust passage and the inside is constituted by a heat transfer chamber through which the heat medium flows, the heat exchange between the heat medium and the exhaust gas is efficiently performed, and the exhaust Heat can be recovered and reused.

  According to a seventh aspect of the present invention, in the configuration of the sixth aspect of the invention, the heat transfer chamber is formed in a double cylinder shape surrounding the outer periphery of the exhaust passage, and the inner chamber or the outer chamber is provided with the above-described heat transfer chamber. A flow path switching means for circulating the heat medium from the heat medium flow path is provided so that the heat transfer amount can be adjusted.

  It can also be constituted by an inner chamber and an outer chamber formed concentrically in the heat transfer chamber. For example, when the exhaust temperature is low, the heat medium is circulated through the inner chamber to recover heat, and the outer chamber is used as a heat retaining layer to increase the temperature raising efficiency. When the exhaust temperature is high, the heat medium is circulated to the outer chamber to prevent the heat medium from being deteriorated, and the inner chamber is used as a heat insulating layer. In this way, the amount of heat received can be changed by changing the flow path of the heat medium according to the exhaust gas temperature, and optimal temperature control can be realized.

  According to an eighth aspect of the present invention, in the exhaust gas treatment apparatus for an internal combustion engine according to the sixth or seventh aspect, a means for switching the heat medium introduced into the heat transfer chamber from the heat medium flow path is provided.

  Preferably, the type of the heat medium introduced into the heat transfer means can be changed. For example, the heat recovery performance is maintained by switching the heat medium introduced from the heat medium flow path into the heat transfer chamber to a heat medium that does not deteriorate at a high temperature when the heat medium is at a high temperature that may deteriorate. The reliability can be improved.

  According to a ninth aspect of the invention, in the configuration of the first to eighth aspects of the invention, the heat recovery means supplies a second heat recovery for supplying heat from the heat transfer means downstream of the catalyst to other parts of the internal combustion engine. Has a passage.

  For example, when heat is required for heating under stable conditions that do not require temperature control of the catalyst, the heat of the exhaust recovered by the heat transfer means is transferred from the second heat recovery passage to another part. It can also be supplied, and the heat of the exhaust can be reused more effectively.

(First embodiment)
Hereinafter, an exhaust treatment apparatus for an internal combustion engine to which the present invention is applied will be described with reference to the drawings. 1 to 4 show a first embodiment of the present invention, FIG. 1 is a diagram illustrating the basic configuration of the entire exhaust treatment apparatus, FIGS. 2 to 4 are its operations, and FIGS. In FIG. 1, an engine 1 that is an internal combustion engine has a general configuration that generates power by combustion of gasoline fuel, diesel fuel, or the like, and an exhaust pipe 11 that is an exhaust passage connected to a combustion chamber of each cylinder. And exhaust gas from combustion of fuel.

  The exhaust pipe 11 is provided with a catalyst 2 for purifying harmful components contained in the exhaust gas, and a heating means 21 for heating the catalyst 2 is installed upstream thereof. The catalyst 2 may be any of a known three-way catalyst known for gasoline engines, a NOx catalyst, a DPF with a catalyst for diesel engines (diesel particulate filter), etc. It has a known structure in which a catalytic metal component is supported on a carrier.

  As the heating means 21, it is desirable to use a fuel combustion type heating device that uses the combustion heat of the fuel. For example, this apparatus is configured such that fuel supplied from a fuel supply passage (not shown) is introduced into a combustion chamber, ignited and combusted, exhaust gas is heated with the combustion heat, and then introduced into the catalyst 2. There is an advantage that the catalyst 2 can be heated with high efficiency and heated with high efficiency. Further, the temperature of the catalyst 2 can be stably controlled by controlling the combustion amount. In addition, a known vehicle heater, for example, an electric heater that generates heat when energized can be used as the heating means 21.

  A temperature sensor 22 that detects the exhaust gas temperature discharged from the engine 1 is disposed upstream of the heating means 21. The ECU 3 as the control means operates the heating means 21 based on the detection result of the temperature sensor 22 and controls the operation of the heat recovery means 4 which is a feature of the present invention to increase the temperature rise at the start of the catalyst 2. Control is performed so that the temperature after starting is properly maintained. This characteristic part will be described in detail below.

  The heat recovery means 4 includes a heat transfer means 41 installed in the exhaust pipe 11 between the heating means 21 and the temperature sensor 22, a heat transfer means 42 installed in the exhaust pipe 11 downstream of the catalyst 2, and these heat transfers. A heat recovery passage 43 connecting the means 41 and 42 and a heat medium transporting means 44 for circulating the heat medium in the heat recovery passage 43 are provided. The heat recovery passage 43 includes a first flow path 431 from the heat transfer means 41 to the heat transfer means 42 and a second flow path 432 from the heat transfer means 42 to the heat transfer means 41, and these first flow paths 431. A heat medium circulation path for transferring heat between the heat transfer means 41 and 42 is formed via the heat medium flowing through the second flow path 432. As the heat medium, for example, engine cooling water (coolant liquid), engine oil, or the like can be used.

  The heat transfer means 41 and 42 are formed of a cylindrical body closed at both ends concentrically disposed on the outer peripheral side of the exhaust pipe 11, and an annular space formed between the cylindrical wall and the outer peripheral wall of the exhaust pipe 11. Are the heat transfer chambers 41a and 42a. The heat transfer chambers 41 a and 42 a of the heat transfer means 41 and 42 have a heat medium inlet and outlet connected to the first flow path 431 or the second flow path 432, and are exhausted through the outer peripheral wall of the exhaust pipe 11. Performs heat exchange between gas and heat medium. At this time, the second flow path 432 is connected to the inlet of the heat transfer means 41, the first flow path 431 is connected to the outlet, the first flow path 431 is connected to the inlet of the heat transfer means 42, and the second flow path is set to the outlet. A flow path 432 is connected.

  FIG. 1 schematically shows the configuration of the present embodiment. The flow channel configuration and arrangement of the first flow channel 431 and the second flow channel 432, and the flow channels 431 and 432 and the heat transfer chambers 41a and 42 are shown. And the arrangement of the inlet and outlet, etc. are set as appropriate. Usually, by arranging the inlet and the outlet at the one end side and the other end side of the annular space portion to be the heat transfer chambers 41a and 42, respectively, the outlets from the inlet to the heat transfer chambers 41a and 42 are provided. An annular flow path is formed, and the heat medium flows smoothly to exchange heat with the exhaust gas.

  The heat medium conveying means 44 includes a pump interposed in the heat recovery passage 43, and is controlled by the ECU 3 to circulate the heat medium in a predetermined direction. The pump does not need to be provided in each of the first flow path 431 and the second flow path 432, and is provided in either one of the heat transfer means 41 and 42 as long as circulation and heat transfer are sufficiently possible. May be. The ECU 3 turns on / off the heat medium transport means 44 according to the temperature of the exhaust gas detected by the temperature sensor 22, and exhausts the heat from the heat transfer means 41 to the heat transfer means 42 or from the heat transfer means 42 to the heat transfer means 42. Move the heat. When the heat transfer is unnecessary, the heat medium transporting unit 44 is stopped.

  2 to 4, the operation of the ECU 3 in the exhaust processing apparatus having the above configuration will be described. The ECU 3 performs temperature increase control at the time of starting the engine 1 to quickly increase the temperature of the catalyst 2 to the activation temperature, while maintaining the temperature of the catalyst 2 so as not to exceed the deterioration temperature, and stable purification performance. To maintain. At this time, effective temperature control is enabled by reusing heat by the heat recovery means 4. In addition, surplus heat that is not used for temperature control of the catalyst 2 is supplied to other parts, so that the generated heat is more effectively reused.

  FIG. 2 shows a case where the exhaust temperature from the engine 1 is lower than the activation temperature of the catalyst 2, and the ECU 3 operates the heating means 21 to introduce the heated exhaust gas into the catalyst 2. At the same time, the heat medium conveying means 44 of the heat recovery means 4 is operated to circulate the heat medium in the heat recovery passage 43. When the engine is cold, the exhaust temperature of the engine 1 is low and the exhaust purification performance of the catalyst 2 is reduced. In this embodiment, the exhaust gas is first heated by the heating means 21 and further the catalyst 2 downstream is heated. To do. Next, when the exhaust gas that has passed through the catalyst 2 passes through the heat transfer means 42, it exchanges heat with the heat medium flowing through the heat transfer chamber 42 a, releases the heat, and is then discharged to the outside.

  The heat recovered by the heat medium is introduced from the second flow path 432 of the heat recovery passage 43 to the heat transfer means 41 on the upstream side of the catalyst 2. While passing through the heat transfer chamber 41a, the heat medium exchanges heat with a lower temperature exhaust gas, releases heat, and then circulates again to the heat transfer means 42 via the first flow path 431. The exhaust gas is heated by heat carried from the downstream side, and further heated by the heating means 21. Since the temperature of the catalyst 2 is quickly raised by the heat of the exhaust gas that has become higher and reaches the activation temperature, the initial purification performance can be greatly improved.

  FIG. 3 shows a case where, for example, the engine 1 is in a high-load operation state, the exhaust temperature is higher than the deterioration temperature of the catalyst 2, and the temperature of the catalyst 2 may rise excessively, leading to deterioration. Therefore, the ECU 3 stops the operation of the heating means 21 so that the exhaust gas is not heated. At the same time, the heat medium conveying means 44 of the heat recovery means 4 is operated to circulate the heat medium in the heat recovery passage 43. When the exhaust temperature of the engine 1 is high, when the exhaust gas passes through the heat transfer means 42, it exchanges heat with the heat medium in the heat transfer chamber 42 a having a relatively low temperature, releases the heat, and then supplies the heat to the catalyst 2. Is done.

  Therefore, the temperature of the exhaust gas introduced into the catalyst 2 can be lowered, the excessive temperature rise of the catalyst 2 is prevented, and the deterioration of the catalyst performance due to deterioration is suppressed. Thereby, the temperature of the catalyst 2 is maintained in an appropriate range, and a stable purification performance is exhibited. On the other hand, the heat recovered by the heat transfer means 42 on the upstream side is carried by the heat medium from the first flow path 431 of the heat recovery passage 43 to the heat transfer means 42 on the downstream side of the catalyst 2. Since the temperature of the exhaust gas that has passed through the catalyst 2 is further lowered, it receives heat from the heat medium flowing through the heat transfer chamber 42a of the heat transfer means 42 and is discharged outside. The heat medium whose temperature has decreased due to heat radiation is circulated to the heat transfer means 41 again via the second flow path 432.

  FIG. 4 shows that when the engine 1 is in a stable running state and the exhaust temperature is higher than the activation temperature of the catalyst 2 (and lower than the deterioration temperature), the catalyst 2 can be sufficiently heated by the heat of the exhaust. 21 is stopped. Further, there is no need to collect the heat downstream of the catalyst 2 and carry it upstream, or conversely, discard the heat upstream, so that the operation of the heat medium conveying means 44 of the heat recovery means 4 is also stopped. . Thereby, the temperature of the catalyst 2 can be stably maintained above the activation temperature, and high purification performance can be exhibited.

  However, in this state, the exhaust gas is discharged while maintaining a relatively high temperature. Therefore, as shown in the drawing, a second heat recovery passage 45 for transporting the heat of the exhaust to other parts of the vehicle and a heat medium transport means 46 can be provided. The second heat recovery passage 45 is connected to, for example, the vehicle compartment heating means 5 and the heat medium transport means 46 and further connected to the engine 1. Similarly to the heat recovery passage 43, the second heat recovery passage 45 is connected to the heat transfer means 42 on the downstream side of the catalyst 2, and the first flow path 451 flows in the direction of introducing the heat medium into the heat transfer chamber 42a. It has the 2nd flow path 452 which flows into the direction which sends out a thermal medium to the vehicle interior heating means 5. As shown in FIG. A reciprocating flow path connecting the vehicle compartment heating means 5 and the engine 1 is constituted by generally known engine cooling water passages 51 and 52.

  According to the above configuration, when the exhaust gas temperature is higher than the activation temperature of the catalyst 2 and the engine warm-up is not completed and the vehicle compartment heating is necessary, the heating unit 21 and the heat medium transport unit 44 are turned off. Only the heat medium conveying means 46 is operated. Thereby, the relatively high-temperature exhaust gas introduced into the heat transfer means 42 on the downstream side of the catalyst 2 exchanges heat with the heat medium passing through the heat transfer chamber 42a, and is discharged after releasing the heat. The recovered heat is supplied from the second flow path 452 of the heat recovery passage 45 through the heat medium conveying means 46 to the vehicle compartment heating means 5 and further to the engine 1 to heat them. Thereafter, the heat medium is circulated again from the first flow path 451 of the second heat recovery passage 45 to the heat transfer means 42.

  FIG. 5 shows the temperature increase effect of the catalyst 2 according to the configuration of the present embodiment. When the engine 1 is started, both the heating means 21 and the heat medium conveying means 44 are turned on to heat the catalyst 2 by heat recovery. The time change of the catalyst temperature in the case of being performed is compared with the case where only the heating means 21 is turned on and the case where both the heating means 21 and the heat medium conveying means 44 are turned off. As is apparent from the figure, when the heating means 21 is activated in the case where nothing is activated, the start of the temperature rise of the catalyst 2 is accelerated and the time until the activation temperature is reached is shortened. In addition, by operating the heat medium conveying means 44, the start of the temperature rise of the catalyst 2 can be further accelerated, and the temperature can be quickly raised to the activation temperature by the rapid temperature rise thereafter.

  FIG. 6 shows the cooling effect of the catalyst 2 according to the configuration of the present embodiment. When high-temperature exhaust gas is discharged from the engine 1 at a high load or the like, the temperature of the catalyst 2 exceeds the deterioration temperature. There is. Even in such a case, the temperature of the catalyst 2 is lowered by operating the heat medium conveying means 44 and recovering the heat of the exhaust gas before being introduced into the catalyst 2, so that the temperature is sufficiently lower than the deterioration temperature. be able to. This effect is proportional to the conveyance speed of the heat medium, and the temperature of the catalyst 2 can be greatly reduced as the conveyance speed increases.

(Second Embodiment)
FIGS. 7-12 is 2nd Embodiment of this invention, and is provided with the structure for preventing deterioration of a thermal medium. 7 to 9 show other examples of the configuration of the heat transfer means 41 and 42, and FIG. 10 shows the overall configuration of the exhaust purification apparatus using the heat transfer means 41 and 42. FIG. 11 is a specific configuration example of the heat medium conveying means 44, and FIG. 12 is a time chart for explaining the operation thereof.

  In FIG. 7, the heat transfer means 41 and 42 of the present embodiment are formed in a double cylinder shape having both ends closed concentrically disposed on the outer peripheral side of the exhaust pipe 11, and an annular shape formed on the inner peripheral side thereof. The space portions are inner chambers 41b and 42b, and the annular space portions formed on the outer peripheral side are outer chambers 41c and 42c. These inner chambers 41b and 42b and outer chambers 41c and 42c constitute heat transfer chambers 41a and 42a. Then, as shown in FIGS. 7 to 9, depending on the exhaust temperature from the engine 1, the first and second flow paths 431 and 432 of the heat recovery passage 43 go to the inner chambers 41 b and 42 b and the outer chambers 41 c and 42 c. Switch the introduction of the heating medium.

  As shown in FIG. 10, in the present embodiment, the first flow path 431 and the second flow path 432 of the heat recovery path 43 have a double path structure having inner flow paths 431a and 432a and outer flow paths 431b and 432b, respectively. To form. As shown in FIGS. 7 and 8, the inner flow paths 431a and 432a are the inner chambers 41b and 42b of the heat transfer chambers 41a and 42a, and the outer flow paths 431b and 432b are the outer chambers 41c of the heat transfer chambers 41a and 42a. 42c. The connecting portions to the inner chambers 41b and 42b and the outer chambers 41c and 42c have inlets and outlets positioned at both ends of the annular space so that the heat medium flows smoothly through the inside. Further, the inner chambers 41b and 42b and the outer chambers 41c and 42c are configured such that the inlet and the outlet are located on the opposite sides and the flow directions are opposed to each other.

  In the present embodiment, in the heat recovery passage 43, the heat medium transport unit 44 is disposed in the middle of the second flow path 432 from the heat transfer unit 41 to the heat transfer unit 41. As shown in detail in FIG. 11, the heat medium transport means 44 includes a heat medium tank 441 communicating with the heat transfer means 41 via the inner flow path 431a and the outer flow path 431b, and a heat medium tank via the on-off valve 442. And a flow path switching valve 445 as a flow path switching means for supplying a heat medium to the inner flow path 431a and the outer flow path 431b on the heat transfer means 42 side.

  An air intake valve 443 is connected between the on-off valve 442 and the pump 444. Accordingly, when the pump 444 is operated with the on-off valve 442 closed, air can be sucked in by the pump negative pressure. Further, by switching the flow path switching valve 445, either the heat medium or the air can be introduced into the inner flow path 431a and the outer flow path 431b. Further, the inner flow path 431a and the outer flow path 431b on the side of the heat transfer means 42 are connected to a merging passage to the heat medium tank 441 via backflow prevention valves 446 and 447, respectively. The heat medium tank 441 is provided with an air vent valve 448, which discharges air flowing in from the inner flow path 431a and the outer flow path 431b and stores only the heat medium.

  The ECU 3 controls the temperature of the catalyst 2 by controlling the heating means 21 and the heat medium conveying means 44 of the heat recovery means 4 based on the detection result of the temperature sensor 22 as in the first embodiment. In the present embodiment, heat to the inner chambers 41b and 42b and the outer chambers 41c and 42c of the heat transfer means 41 and 42 is achieved by turning on and off the on-off valve 442 and the pump 444 of the heat medium transport means 44 and switching the flow path switching valve 445. Effective heat recovery is performed while controlling the introduction of the medium and preventing the heat medium from deteriorating.

  The operation of the ECU 3 in the exhaust processing apparatus having the above configuration will be described with reference to FIGS. Here, the heat medium is a coolant liquid, and its deterioration temperature is, for example, 180 ° C. (inner chambers 41b, 42b), 500 ° C. (outer chamber 41c, 42c), the catalyst activation temperature is, for example, 250 ° C., and the catalyst deterioration temperature is, for example, 500 ° C. It explains as being. FIG. 7 shows a case where the exhaust temperature from the engine 1 is lower than the activation temperature of the catalyst 2. The ECU 3 operates the heating means 21 in FIG. 10 to introduce the heated exhaust gas into the catalyst 2. At the same time, the on-off valve 442 of the heat medium conveying means 44 is opened and the pump 444 is operated to circulate the heat medium in the heat recovery passage 43. The channel switching valve 445 is switched to the inner channel 432 a side of the second channel 432.

  As a result, as shown in FIG. 7, the heat medium is introduced into the inner chambers 41b and 42b in the heat transfer chambers 41a and 42a of the heat transfer means 41 and 42, respectively. At this time, an air layer is formed in the outer chambers 41c and 42c, and functions as a heat insulating layer that prevents heat radiation from the inner chambers 41b and 42b through which the heat medium flows. That is, in the inner chamber 42 b of the heat transfer means 42, the heat medium efficiently receives the heat of the exhaust gas, and is introduced into the inner chamber 41 b of the heat transfer means 41 through the recovery passage 432 to release the recovered heat to the outside. Heat exchange with exhaust gas. Therefore, the temperature rise of the catalyst 2 can be promoted by using the exhaust heat more effectively.

  FIG. 8 shows the case where the exhaust temperature from the engine 1 is higher than the deterioration temperature (for example, 180 ° C.) of the heat medium. Prior to this, the ECU 3 turns on the heating means 21 in FIG. 10 and the pump 444 of the heat medium conveying means 44. Is turned on, and the on-off valve 442 is closed with the flow path switching valve 445 switched to the inner flow path 432a side of the second flow path 432 (see FIG. 12). Then, supply of the heat medium from the heat medium tank 441 is stopped, and the air intake valve 433 is opened by the negative pressure of the pump 444, so that the air flows from the flow path switching valve 445 to the inner flow path 432a of the second flow path 432. Sucked into.

  Thereby, as shown in FIG. 8, air is introduced into the inner chambers 41b and 42b in the heat transfer chambers 41a and 42a of the heat transfer means 41 and 42, respectively. Next, when the flow path switching valve 445 is switched to the outer flow path 432b side of the second flow path 432 and the on-off valve 442 is opened in this state, heat is transferred from the heat medium tank 441 to the outer flow path 432b of the second flow path 432. The medium is supplied, and the heat medium is introduced into the outer chambers 41c and 42c of the heat transfer chambers 41a and 42a. At this time, the air layer in the inner chambers 41 b and 42 b functions as a heat insulating layer interposed between the outer chambers 41 c and 42 c and the exhaust pipe 11. That is, by preventing the heat medium in the outer chambers 41c and 42c from coming into direct contact with the exhaust pipe 11 through which the high-temperature exhaust gas flows, heat exchange is effectively performed while preventing deterioration of the heat medium, The recovered heat can be reused to rapidly raise the catalyst 2 to the activation temperature.

  In FIG. 12, when the exhaust temperature from the engine 1 reaches the activation temperature of the catalyst 2 (for example, 250 ° C.), the heating means 21 for heating the catalyst 2 is stopped. Further, when the exhaust temperature from the engine 1 rises and approaches the deterioration temperature (for example, 500 ° C.) of the heat medium flowing through the outer chambers 41 c and 42 c, the ECU 3 closes the on-off valve 442 of the heat medium transport unit 44. Then, since the air intake valve 433 is opened by the negative pressure of the pump 444, air is sucked from the flow path switching valve 445 into the outer flow path 432b of the second flow path 432 and introduced into the outer chambers 41c and 42c. Next, when the pump 444 is turned off, the inner chambers 41b and 42b and the outer chambers 41c and 42c of the heat transfer chambers 41a and 42a become air layers (retention).

  FIG. 9 shows the case where the exhaust temperature from the engine 1 is further higher than the catalyst deterioration temperature (for example, 900 ° C.). In the state where both are air layers, the flow path switching valve 445 of the heat transfer means 44 in FIG. 10 is switched to the inner flow path 432a side of the first flow path 432, and in this state, the pump 444 is turned on. Operate.

  As a result, air as a heat medium flows between the heat transfer means 41 and 42. In other words, since the on-off valve 442 is closed, air is taken in from the air intake valve 433 at a negative pressure of the pump 444, passes through the inner flow path 432a of the second flow path 432 from the flow path switching valve 445, and is upstream of the catalyst 2. It is supplied to the heat transfer means 41. In the heat transfer means 41, the heat of the high-temperature exhaust gas is released into the air flowing through the inner chamber 41b of the heat transfer chamber 41a, and the heat transfer means downstream of the catalyst 2 through the inner flow path 431a of the first flow path 431. 42. In the heat transfer means 42, the heat carried by the air flowing through the inner chamber 41b of the heat transfer chamber 42a is released to the relatively low temperature exhaust gas. Therefore, it is possible to prevent the exhaust gas having a high temperature exceeding the deterioration temperature from flowing into the catalyst 2, suppress the deterioration, and exhibit good purification performance.

  As described above, according to the present invention, the temperature of the catalyst is increased by effectively reusing the heat of the exhaust gas, while the temperature of the catalyst is efficiently controlled by suppressing the deterioration of the heat medium and the catalyst due to the high-temperature exhaust gas. Can be realized. Therefore, it is possible to obtain an exhaust treatment apparatus having a simple configuration and high performance and excellent reliability.

1 is an overall configuration diagram of an exhaust treatment apparatus for an internal combustion engine according to a first embodiment of the present invention. It is a figure explaining the operation | movement (when exhaust gas temperature is lower than catalyst activation temperature) of 1st Embodiment of this invention. It is a figure explaining the operation | movement (when exhaust gas temperature is higher than catalyst deterioration temperature) of 1st Embodiment of this invention. It is a figure explaining operation | movement (when exhaust gas temperature is higher than catalyst activation temperature) of 1st Embodiment of this invention, and is the figure which provided the 2nd heat recovery means in the basic composition of 1st Embodiment. It is a figure for demonstrating the temperature rising effect in 1st Embodiment of this invention. It is a figure for demonstrating the cooling effect in 1st Embodiment of this invention. It is principal part sectional drawing of the exhaust-gas treatment apparatus in 2nd Embodiment of this invention, and is a figure explaining operation | movement when exhaust gas temperature is higher than catalyst activation temperature. It is principal part sectional drawing of the exhaust-gas treatment apparatus in 2nd Embodiment of this invention, and is a figure explaining operation | movement when exhaust gas temperature is higher than heat-medium degradation temperature. It is principal part sectional drawing of the exhaust-gas treatment apparatus in 2nd Embodiment of this invention, and is a figure explaining operation | movement when exhaust gas temperature is higher than catalyst deterioration temperature. It is a whole block diagram of the exhaust-air-treatment device for internal combustion engines in 2nd Embodiment of this invention. It is a figure which shows the structure of the thermal-medium conveyance means which is the principal part of the exhaust-air-treatment apparatus for internal combustion engines in 2nd Embodiment of this invention. It is a figure for demonstrating operation | movement of the control means in the exhaust processing apparatus of 2nd Embodiment of this invention.

Explanation of symbols

1 Engine 11 Exhaust pipe (exhaust passage)
2 Catalyst 21 Heating means 3 ECU (Control means)
4 Heat recovery means 41, 42 Heat transfer means 41a, 42a Heat transfer chamber 41b, 42b Inner chamber 41c, 42c Outer chamber 43 Heat recovery passage 431 First flow path 432 Second flow path 44 Heat medium transport means 441 Heat medium tank 442 On-off valve 443 Air intake valve 444 Pump 445 Flow path switching valve

Claims (9)

In an exhaust treatment apparatus for an internal combustion engine comprising a catalyst provided in an exhaust passage of an internal combustion engine, a heating means for heating the catalyst, and a heat recovery means for recovering heat of the exhaust,
The heat recovery means includes a pair of heat transfer means installed respectively upstream and downstream of the catalyst, a heat recovery flow path connecting the pair of heat transfer means, and a heat medium provided in the heat recovery flow path Have transport means,
According to the present invention, there is provided control means for controlling the operation of the heating means and the heat medium transport means and the direction of heat recovery when the heat medium transport means is operated according to the temperature of the exhaust gas discharged to the exhaust passage. An exhaust treatment device for an internal combustion engine. The exhaust treatment device for an internal combustion engine according to claim 1, wherein the control means includes:
When the temperature of the exhaust gas is lower than the activation temperature of the catalyst, the heating means is turned on, the heat medium conveying means is turned on, and the heat recovered by the heat transfer means downstream of the catalyst is upstream heat transfer means. An exhaust treatment apparatus for an internal combustion engine characterized by being returned to   2. The exhaust gas treatment apparatus for an internal combustion engine according to claim 1, wherein when the temperature of the exhaust gas is equal to or higher than the deterioration temperature of the catalyst, the heating means is turned off and the heat medium conveying means is turned on to upstream the catalyst. An exhaust processing apparatus for an internal combustion engine, wherein the heat recovered by the heat transfer means is discarded through the downstream heat transfer means to control the temperature rise and cooling of the catalyst.   4. The exhaust treatment device for an internal combustion engine according to claim 1, wherein the control means turns off the heating means when the temperature of the exhaust gas is equal to or higher than the activation temperature of the catalyst. An exhaust treatment device for an internal combustion engine.   5. The exhaust gas treatment apparatus for an internal combustion engine according to claim 1, wherein the heat recovery flow path has a pair of heat medium flow paths that are respectively connected at both ends to the pair of heat transfer means. The pair of heat medium flow paths and the pair of heat transfer means form a heat medium circulation path to move the heat of exhaust gas from one of the heat transfer means to the other. Exhaust treatment device.   6. The exhaust gas processing apparatus for an internal combustion engine according to claim 5, wherein the heat transfer means is disposed in contact with an outer periphery of the exhaust passage and has an inlet and an outlet respectively communicating with the pair of heat medium flow paths. An exhaust treatment apparatus for an internal combustion engine, comprising: a chamber, wherein a heat medium passing through the heat transfer chamber exchanges heat with the exhaust in the exhaust passage.   The exhaust treatment device for an internal combustion engine according to claim 6, wherein the heat transfer chamber is formed in a double cylinder shape surrounding the outer periphery of the exhaust passage, and the heat medium flow is provided in one of the inner chamber and the outer chamber. An exhaust treatment apparatus for an internal combustion engine, characterized in that a flow path switching means for circulating a heat medium from the path is provided so that the amount of heat exchange can be adjusted.   8. An exhaust treatment apparatus for an internal combustion engine according to claim 6 or 7, further comprising means for switching the heat medium introduced from the heat medium flow path into the heat transfer chamber.   9. The exhaust gas treatment apparatus for an internal combustion engine according to claim 1, wherein the heat recovery means supplies heat from a heat transfer means downstream of the catalyst to other parts of the internal combustion engine. An exhaust treatment apparatus for an internal combustion engine having a heat recovery passage.

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