JP4327768B2 - Oxygen supply device for internal combustion engine - Google Patents

Description

  The present invention relates to an oxygen supply device for an internal combustion engine.

  Patent Document 1 discloses a secondary air supply device that supplies air to an exhaust port upstream of the three-way catalyst in order to increase the temperature of the three-way catalyst disposed in the exhaust pipe of the internal combustion engine. When air is supplied from the secondary air supply device to the exhaust port upstream of the three-way catalyst, oxygen in the supplied air reacts with unburned fuel in the exhaust gas, and with the reaction heat generated at that time. The temperature of the exhaust gas is raised, and the temperature of the three-way catalyst is raised by the exhaust gas raised in temperature.

  Further, when supplying air to the exhaust port upstream of the three-way catalyst to increase the temperature of the three-way catalyst as in Patent Document 1, if there is a large amount of unburned fuel in the exhaust gas, the secondary air supply device The amount of heat generated by the reaction between oxygen in the air supplied to the exhaust port and unburned fuel in the exhaust gas increases, and accordingly, the temperature of the three-way catalyst can be quickly raised. Therefore, in Patent Document 1, when air is supplied from the secondary air supply device to the exhaust port upstream of the three-way catalyst in order to increase the temperature of the three-way catalyst, the amount of fuel injected from the fuel injection valve is increased. The amount of unburned fuel in the exhaust gas is increased.

  By the way, the secondary air supply device described in Patent Document 1 has an electric air pump, and air is supplied from the air pump to the exhaust port. In this case, air is supplied from the air pump to the exhaust port. Therefore, it takes time for the air pump to discharge the rated amount of air after supplying power to the air pump, and it takes time for the air from the air pump to be actually supplied to the exhaust port. Here, if the amount of fuel injected from the fuel injection valve begins to increase at the same time as the supply of power to the air pump begins, the amount of air actually supplied from the air pump to the exhaust port will not be sufficient. The amount of unburned fuel in the gas will increase. Therefore, according to this, the amount of unburned fuel remaining in the exhaust gas without reacting with air increases, and the unburned fuel may be released into the atmosphere.

  Therefore, in Patent Document 1, even if electric power starts to be supplied to the air pump, an increase in the amount of fuel injected from the fuel injection valve is waited until a sufficient amount of air is actually supplied from the air pump to the exhaust port. I am doing so.

JP 2004-124788 A “Fuel supply control device for internal combustion engine”, Toyota Technical Disclosure Collection, January 31, 2003, issue number 14148

  Incidentally, as described above, in Patent Document 1, in the case where the temperature of the three-way catalyst is increased, when the timing for starting the increase of the fuel injected from the fuel injection valve is determined, power is supplied to the air pump. Only the time until the amount of air supplied from the air pump to the exhaust port becomes a sufficient amount is considered. However, in practice, it takes time from the start of increasing the amount of fuel injected from the fuel injection valve until the exhaust gas containing a large amount of unburned fuel reaches the exhaust port.

  Therefore, when the amount of air supplied from the air pump to the exhaust port becomes a sufficient amount, if the fuel injection amount starts to increase, the air supplied from the air pump to the exhaust port is wasted.

  In view of such circumstances, an object of the present invention is to increase the amount of unburned fuel in the exhaust gas, supply oxygen into the exhaust gas, and react the unburned fuel in the exhaust gas with oxygen. The unburned fuel and oxygen supplied to the exhaust gas are allowed to react with oxygen without wasting them.

  In order to solve the above-mentioned problems, in a first aspect of the invention, a fuel supply means for supplying fuel and an oxygen supply means for supplying oxygen are provided, and the fuel supplied from the fuel supply means and the oxygen supply means Oxygen supply for an internal combustion engine that joins oxygen to be supplied at a predetermined joining point to react these fuel and oxygen, and raises the temperature of the catalyst disposed in the exhaust passage with heat generated by the reaction. In the apparatus, when the temperature of the catalyst is to be raised, the fuel first supplied from the fuel supply means and the oxygen supplied first from the oxygen supply means reach the predetermined joining point almost simultaneously. At least one of a timing for starting to supply fuel from the fuel supply means and a timing for starting to supply oxygen from the oxygen supply means is controlled.

  According to a second invention, in the first invention, the oxygen supply means includes a pump for discharging oxygen and an oxygen supply pipe for connecting the pump to an exhaust passage upstream of the catalyst at a predetermined connection point. When the temperature of the catalyst is to be increased, oxygen is supplied from the pump to the exhaust passage upstream of the catalyst via an oxygen supply pipe. When the temperature of the catalyst is to be increased, the oxygen supply means first The timing at which the supplied oxygen reaches the predetermined joining point is the discharge pressure of the pump, the flow resistance of the oxygen supply pipe, the volume in the oxygen supply pipe from the pump to the predetermined connection point, and the exhaust gas upstream of the catalyst. It is estimated based on at least one of the pressure in the passage.

  According to a third aspect, in the second aspect, the pump is an air pump that discharges air.

  According to a fourth aspect, in any one of the first to third aspects, when the fuel supply means is a fuel injection valve that supplies fuel to the combustion chamber of the internal combustion engine, and the temperature of the catalyst should be increased. A fuel injection valve that injects a larger amount of fuel than a normal amount, and when the temperature of the catalyst is to be raised, the timing at which the fuel supplied from the fuel injection valve first reaches the predetermined joining point is It is estimated based on at least one of the amount of air sucked into the combustion chamber and the timing at which a command to inject a larger amount of fuel than the normal amount is issued to the fuel injection valve.

  According to the present invention, the fuel supplied first from the fuel supply means and the oxygen supplied first from the oxygen supply means are merged substantially simultaneously, so that these fuel and oxygen can be used without wasting both fuel and oxygen. Can be reacted.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a main body of an internal combustion engine, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an intake port, 7 is an intake valve, 8 is an exhaust port, and 9 is an exhaust valve. Each is shown. An intake pipe 10 is connected to the intake port 6. On the other hand, an exhaust pipe 11 is connected to the exhaust port 8. A fuel injection valve 12 that supplies fuel to the combustion chamber 5 by injecting fuel into the intake port 6 is attached to the cylinder head 3. A three-way catalyst 13 is disposed in the exhaust pipe 11.

  When the temperature of the three-way catalyst 13 is higher than a certain temperature (so-called activation temperature), if the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 13 is close to the theoretical air-fuel ratio, hydrocarbons (HC) in the exhaust gas, It is a catalyst that simultaneously purifies carbon monoxide (CO) and nitrogen oxides (NOx) with a high purification rate.

  Further, a secondary air supply device 14 that injects air to the exhaust port 8 is connected to the cylinder head 3. The secondary air supply device 14 has an electric air pump 15 of a type that operates when electric power is supplied. The air pump 15 is connected to the exhaust port 8 via the air supply pipe 16, and the discharge port 17 of the air supply pipe 16 opens into the exhaust port 8. The air supply pipe 16 is provided with a control valve 18 for opening and closing the air supply pipe 16 and a check valve 19 for preventing exhaust gas from the exhaust port 8 from flowing back through the air supply pipe 16. Has been. A pressure sensor 20 that detects the pressure in the air supply pipe 16 is attached to the air supply pipe 16 between the air pump 15 and the control valve 18. In the present embodiment, based on the output from the pressure sensor 20, not only the pressure in the air supply pipe 16 is estimated, but also the flow rate of the air flowing in the air supply pipe 16 is estimated.

  When power is supplied to the air pump 15, the air pump 15 sucks air through the air filter 21 and discharges the sucked air to the air supply pipe 16. Here, when the control valve 18 is closed, air does not flow downstream from the control valve 18, so that the pressure in the air supply pipe 16 between the air pump 15 and the control valve 18 gradually increases. In the present embodiment, at least the pressure in the air supply pipe 16 between the air pump 15 and the control valve 18 rises to a pressure at which the exhaust gas discharged from the combustion chamber 5 does not flow back through the air supply pipe 16. When the above condition is satisfied, the control valve 18 is opened. When the control valve 18 is opened, air is supplied to the exhaust port 8 through the air supply pipe 16.

  By the way, in this embodiment, when the temperature of the three-way catalyst 13 is lower than a predetermined temperature (especially so-called activation temperature), the temperature of the three-way catalyst 13 is set to a predetermined temperature (particularly the activation temperature) as follows. Raise to. That is, when the temperature of the three-way catalyst 13 is lower than the predetermined temperature, the amount of fuel injected from the fuel injection valve 12 (hereinafter also referred to as “fuel injection amount”) is set to the normal fuel injection amount (that is, the three-way catalyst 13). The amount of fuel required to drive the internal combustion engine when the temperature of the engine is higher than the predetermined temperature), and air is supplied from the secondary air supply device 14 to the exhaust port 8. According to this, exhaust gas containing a large amount of unburned fuel (hereinafter also referred to as “rich exhaust gas”) is discharged from the combustion chamber 5, and air from the secondary air supply device 14 is combined with this exhaust gas. These unburned fuels and air (especially oxygen in the air) cause an oxidation reaction. For this reason, the temperature of the exhaust gas is raised, and the exhaust gas whose temperature has been raised flows into the three-way catalyst 13. As a result, the temperature of the three-way catalyst 13 is raised. When the temperature of the three-way catalyst 13 reaches a predetermined temperature, the fuel injection amount is returned to the normal fuel injection amount, and the supply of air from the secondary air supply device 14 to the exhaust port 8 is stopped.

  It should be noted that when the temperature of the three-way catalyst 13 is raised to a predetermined temperature, the amount of fuel injection is increased (hereinafter referred to as “increased fuel amount”) and the amount of air supplied from the secondary air supply device 14 (hereinafter “ The “air supply amount”) may be, for example, a preset constant amount or an amount determined according to the temperature of the three-way catalyst 13 with respect to a predetermined temperature. Here, in the case of determining the increased fuel amount and the air supply amount according to the temperature of the three-way catalyst 13 with respect to the predetermined temperature, from the viewpoint of causing the temperature of the three-way catalyst 13 to reach the predetermined temperature earlier, the predetermined temperature On the other hand, it is preferable to increase the fuel amount and the air supply amount as the temperature of the three-way catalyst 13 is lower.

  By the way, in the present embodiment, when the temperature of the three-way catalyst 13 is lower than the predetermined temperature, basically, as described above, the temperature of the three-way catalyst 13 is raised to the predetermined temperature. From the viewpoint of reacting these unburned fuel and air without wasting neither unburned fuel in the exhaust gas nor air supplied from the secondary air supply device 14, the fuel injection amount is set to the normal fuel injection amount. The timing for starting to supply more air and the timing for starting to supply air from the secondary air supply device 14 to the exhaust port 8 (in this embodiment, the timing to start supplying power to the air pump 15) are controlled as follows.

  That is, when raising the temperature of the three-way catalyst 13, the unburned fuel in the exhaust gas and the air supplied from the secondary air supply device 14 are allowed to react with each other without wasting them. In order to achieve this, an exhaust gas (rich exhaust gas) and a secondary air supply device containing unburned fuel in an amount larger than the normal amount by increasing the fuel injection amount from the normal fuel injection amount 14 is a point where these rich exhaust gas and air merge (in this embodiment, a point in the vicinity of the outlet 17 of the air supply pipe 16 that opens to the exhaust port 8, and this point is referred to below. It is sufficient to reach the “confluence point” at least substantially at the same time.

  Therefore, in the present embodiment, the fuel injection amount is set to the normal fuel injection amount so that the rich exhaust gas discharged from the combustion chamber 5 and the air supplied from the secondary air supply device 14 reach the merging point substantially simultaneously. The timing at which the amount of air starts to be larger than the amount and the timing at which air is started to be supplied from the secondary air supply device 14 to the exhaust port 8 (in this embodiment, the timing at which power is supplied to the air pump 15) are controlled.

  2 and 3 show an example of a routine for controlling the increase of the fuel injection amount and the opening of the control valve 18 in order to increase the temperature of the three-way catalyst 13 according to the above-described embodiment. In the routine of FIG. 2 and FIG. 3, first, in step 10, the shortest time TA required for the air to reach the junction is calculated after supplying power to the air pump 15. That is, when supplying air from the secondary air supply device 14 to the junction, first, power is supplied to the air pump 15. Then, the air pump 15 starts to operate. At this time, the control valve 18 is kept closed. When the pressure in the air supply pipe 16 between the air pump 15 and the control valve 18 reaches a certain predetermined pressure, the control valve 18 is permitted to open. Here, when the control valve 18 is opened, the air passes through the control valve 18 and reaches the joining point via the air supply pipe 16. Therefore, it takes a certain time from the start of power supply to the air pump 15 until the air reaches the junction. In step 10, when the pressure in the air supply pipe 16 between the air pump 15 and the control valve 18 reaches a predetermined pressure and the control valve 18 is opened at the same time, power is supplied to the air pump 15. The time TA until the air reaches the merging point is calculated.

  Here, the time TA is the discharge pressure of the air pump 15 that affects the time TA, the flow resistance of the air supply pipe 16, the volume in the air supply pipe 16 from the air pump 15 to the outlet 17 of the air supply pipe 16, It is calculated based on at least one of parameters such as pressure in the exhaust passage upstream of the original catalyst 13 (this is expressed by combining the exhaust pipe 11 and the exhaust port 8). As the tendency, the higher the discharge pressure of the air pump 15, the smaller the flow resistance of the air supply pipe 16, and the smaller the volume in the air supply pipe 16 from the air pump 15 to the discharge port 17 of the air supply pipe 16. As the pressure in the exhaust passage upstream of the three-way catalyst 13 is lower, the time TA is shorter.

  Then, in step 11, it takes from the time when a command for increasing the fuel injection amount to the normal fuel injection amount (hereinafter referred to as “increase command”) until the rich exhaust gas reaches the junction. The shortest time TB is calculated. That is, when increasing the fuel injection amount from the normal fuel injection amount, first, a command is issued to the fuel injection valve 12 to make the fuel injection amount larger than the normal fuel injection amount. Then, the fuel injection valve 12 injects a larger amount of fuel than the normal fuel injection amount at the time of fuel injection immediately after that. Then, in the exhaust stroke immediately after that, rich exhaust gas is discharged from the combustion chamber 5 to the exhaust port 8 and reaches the junction. Therefore, it takes a certain amount of time for the rich exhaust gas to reach the merge point after a command for increasing the fuel injection amount to be greater than the normal fuel injection amount is issued to the fuel injection valve 12. Become. In step 11, the time TB from when the command for increasing the fuel injection amount to the normal fuel injection amount is issued to the fuel injection valve 12 until the rich exhaust gas reaches the junction is calculated.

  Here, the time TB is calculated based on at least one of parameters such as the amount of air sucked into the combustion chamber 5 that affects the time TB, the timing at which a command for increasing the fuel injection amount is issued, and the like. Is done. The tendency is that the more the amount of air sucked into the combustion chamber 5 is, and the closer the timing at which a command for increasing the fuel injection amount is issued is closer to the timing at which fuel is injected from the fuel injection valve 12, the longer the time is. TB is short.

  Next, at step 12, it is determined whether or not the temperature TC of the three-way catalyst 13 is lower than a predetermined temperature TCth (TC <TCth). That is, at step 12, it is determined whether or not the rich exhaust gas should be supplied to the merging point by operating the air pump 15 to supply air to the merging point and increasing the fuel injection amount from the normal amount. The When it is determined that TC ≧ TCth, the routine proceeds to step 20, and when the fuel injection amount is not increased, that is, when the fuel injection amount is the normal fuel injection amount. As it is, the fuel injection amount is maintained at the normal fuel injection amount, and when the fuel injection amount is increased, the fuel injection amount is increased and the fuel injection amount is returned to the normal fuel injection amount. .

  Next, in step 21, when the control valve 18 is closed, the closed state is maintained, and when the control valve 18 is opened, the control valve 18 is closed. Next, in step 22, when the operation of the air pump 15 is stopped, the stopped state is maintained. When the air pump 15 is operated, the operation is stopped and the routine is ended.

  On the other hand, when it is determined in step 12 that TC <TCth, the routine proceeds to step 13 where it is determined whether or not the air pump 15 is allowed to operate. That is, if the operation time at the time of the previous operation of the air pump 15 is relatively long, the temperature of the air pump 15 itself becomes high. If the air pump 15 is operated in this state, the air pump 15 may be burned. When the time elapsed since the previous operation of the air pump 15 was stopped is relatively short, if the air pump 15 is operated again, the operation and stop of the air pump 15 are repeated in a short time. This also degrades the 15 drivers.

  Therefore, in step 13, the operation time at the time of the previous operation of the air pump 15 is relatively short and / or the operation time at the time of the operation of the previous air pump 15 is relatively long, but the operation of the previous air pump 15 is not performed. A long time has passed so that the temperature of the air pump 15 is sufficiently lowered after being stopped, and / or a long time has passed so as not to deteriorate the driver of the air pump 15 after the previous operation of the air pump 15 is stopped. It is determined that the air pump 15 is in a state where the operation may be permitted.

  If it is determined in step 13 that the air pump 15 is not in a state that permits its operation, steps 20 to 22 are executed as described above. On the other hand, when it is determined in step 13 that the air pump 15 is in a state in which its operation may be permitted, the routine proceeds to step 14.

  In step 14, the time TA calculated in step 10 is compared with the time TB calculated in step 11. That is, a time TA from when power is supplied to the air pump 15 until the air reaches the junction, and a time TB from when the increase command is issued to the fuel injection valve 12 until the rich exhaust gas reaches the junction. To be compared.

  Here, when it is determined that the time TA is longer than the time TB (TA> TB), that is, when it is determined that the rich exhaust gas reaches the merging point earlier than the air, in step 15, the air pump Power is supplied to 15 to start the operation of the air pump 15. In step 16, it is determined whether or not the pressure P in the air supply pipe 16 between the air pump 15 and the control valve 18 exceeds a predetermined pressure Pth (P> Pth). Here, when it is determined that P ≦ Pth, step 16 is repeated until it is determined that P> Pth. On the other hand, when it is determined at step 16 that P> Pth, the routine proceeds to step 17 where the control valve 18 is opened.

  Next, in step 18, it is determined whether or not a difference time ΔT between the time TA calculated in step 10 and the time TB calculated in step 11 has elapsed. Here, when it is determined that the time ΔT has not elapsed, step 18 is repeated until it is determined that the time ΔT has elapsed. On the other hand, when it is determined in step 18 that the time ΔT has elapsed, the routine proceeds to step 19, where an increase command is issued to the fuel injection valve 12 to start increasing the fuel injection amount.

  On the other hand, when it is determined in step 14 that TA ≦ TB, that is, when it is determined that air reaches the confluence at an earlier time than the rich exhaust gas, the routine proceeds to step 23 where an increase command is issued to the fuel. The injection valve 12 is started to start increasing the fuel injection amount.

  Next, in step 24, it is determined whether or not a difference time ΔT between the time TA calculated in step 10 and the time TB calculated in step 11 has elapsed. Here, when it is determined that the time ΔT has not elapsed, step 24 is repeated until it is determined that the time ΔT has elapsed. On the other hand, when it is determined at step 24 that the time ΔT has elapsed, the routine proceeds to step 25 where power is supplied to the air pump 15 to start the operation of the air pump 15. In step 26, it is determined whether or not the pressure P in the air supply pipe 16 between the air pump 15 and the control valve 18 exceeds a predetermined pressure Pth (P> Pth). If it is determined that P ≦ Pth, step 26 is repeated until it is determined that P> Pth. On the other hand, when it is determined in step 26 that P> Pth, the routine proceeds to step 27 to open the control valve 18.

  The example of the routine described above is based on the assumption that air may reach the merging point earlier than the rich exhaust gas when power is supplied to the air pump 15 at the same time that the increase command is issued. However, if the rich exhaust gas reaches the merging point earlier than the air in any case when the supply of power to the air pump 15 is started at the same time as the increase command is issued, FIG. 4 and FIG. In order to increase the temperature of the three-way catalyst 13 in accordance with the routine shown in FIG. 6, the increase in the fuel injection amount and the opening of the control valve 18 may be controlled.

  That is, in the routines of FIGS. 4 and 5, first, in step 30, the control valve 18 is opened in a state where the pressure in the air supply pipe 16 between the air pump 15 and the control valve 18 exceeds a predetermined pressure. When the valve is opened, a time Ta required from the time when the control valve 18 is opened until the air reaches the merging point is calculated. Here, the time Ta is the same as described with reference to the routines of FIGS. 2 and 3, the discharge pressure of the air pump 15 affecting the time Ta, the flow resistance of the air supply pipe 16, the air from the air pump 15. It is calculated based on at least one of parameters such as the volume in the air supply pipe 16 to the discharge port 17 of the supply pipe 16 and the pressure in the exhaust passage upstream of the three-way catalyst 13.

  Next, in step 31, the time Tb required for the rich exhaust gas to reach the junction is calculated after issuing a command (increase command) for increasing the fuel injection amount from the normal fuel injection amount. Is done. Here, the time Tb is also increased in order to increase the amount of air sucked into the combustion chamber 5 that affects the time Tb and the amount of fuel injection, as described with reference to the routines of FIGS. Is calculated based on at least one of parameters such as the timing at which the command is issued.

  Next, at step 32, it is judged if the temperature TC of the three-way catalyst 13 is lower than a predetermined temperature TCth (TC <TCth). When it is determined that TC ≧ TCth, the routine proceeds to step 40, where the fuel injection amount is not increased, that is, when the fuel injection amount is the normal fuel injection amount. As it is, the fuel injection amount is maintained at the normal fuel injection amount, and when the fuel injection amount is increased, the fuel injection amount is increased and the fuel injection amount is returned to the normal fuel injection amount. . Next, in step 41, when the control valve 18 is closed, the closed state is maintained, and when the control valve 18 is opened, the control valve 18 is closed. Next, at step 42, when the operation of the air pump 15 is stopped, the stopped state is maintained, and when the air pump 15 is operated, the operation is stopped and the routine is ended.

  On the other hand, when it is determined at step 42 that TC <TCth, the routine proceeds to step 43, where it is determined whether or not the air pump 15 is allowed to operate as in step 13 of FIG. Determined. If it is determined in step 33 that the air pump 15 is not in a state of permitting its operation, steps 40 to 42 are executed as described above. On the other hand, when it is determined in step 33 that the air pump 15 is in a state where the operation may be permitted, the process proceeds to step 34 to supply power to the air pump 15 to start the operation of the air pump 15.

  Next, in step 35, it is determined whether or not the pressure P in the air supply pipe 16 between the air pump 15 and the control valve 18 exceeds a predetermined pressure Pth (P> Pth). Here, when it is determined that P ≦ Pth, step 35 is repeated until it is determined that P> Pth. On the other hand, when it is determined in step 35 that P> Pth, the process proceeds to step 36.

  In step 36, the time Ta calculated in step 30 is compared with the time Tb calculated in step 31. That is, there is a time Ta from when the control valve 18 is opened until the air reaches the merging point, and a time Tb from when the increase command is issued to the fuel injection valve 12 until the rich exhaust gas reaches the merging point. To be compared. Here, when it is determined that the time Ta is longer than the time Tb (Ta> Tb), that is, when it is determined that the rich exhaust gas reaches the merging point earlier than the air, the routine proceeds to step 37. Then, the control valve 18 is opened.

  Next, in step 38, it is determined whether or not a difference time ΔT between the time Ta calculated in step 30 and the time Tb calculated in step 31 has elapsed. Here, when it is determined that the time ΔT has not elapsed, step 38 is repeated until it is determined that the time ΔT has elapsed. On the other hand, when it is determined in step 38 that the time ΔT has elapsed, the routine proceeds to step 39, where an increase command is issued to the fuel injection valve 12 to start increasing the fuel injection amount.

  On the other hand, when it is determined at step 36 that Ta ≦ Tb, that is, when it is determined that air reaches the confluence at a speed earlier than the rich exhaust gas, the routine proceeds to step 43 where an increase command is issued. The injection valve 12 is started to start increasing the fuel injection amount.

  Next, at step 44, it is determined whether or not a difference time ΔT between the time Ta calculated at step 30 and the time Tb calculated at step 31 has elapsed. If it is determined that time ΔT has not elapsed, step 44 is repeated until it is determined that time ΔT has elapsed. On the other hand, when it is determined at step 44 that the time ΔT has elapsed, the routine proceeds to step 45 where the control valve 18 is opened.

  In the above-described embodiment, the present invention is applied to an apparatus that supplies air to the exhaust passage upstream of the three-way catalyst when the temperature of the three-way catalyst should be raised. The present invention can be applied to the case where oxygen is supplied to the exhaust passage upstream of the three-way catalyst at the temperature of the three-way catalyst. Further, in the above-described embodiment, the present invention is applied when the temperature of the three-way catalyst is increased in the one having the three-way catalyst. More generally, the specific component in the exhaust gas is used. The present invention can be applied to a case where the temperature of the catalyst is increased in a device having a catalyst to be purified.

It is the figure which showed the internal combustion engine provided with the secondary air supply apparatus of this invention. It is the figure which showed a part of example of the routine which controls the increase in fuel injection quantity and the valve opening of a control valve according to 1st Embodiment of this invention. It is the figure which showed a part of example of the routine which controls the increase in fuel injection quantity and the valve opening of a control valve according to one Embodiment of this invention. It is the figure which showed a part of example of the routine which controls the increase in fuel injection quantity and the valve opening of a control valve according to 2nd Embodiment of this invention. It is the figure which showed a part of example of the routine which controls the increase in fuel injection quantity and the valve opening of a control valve according to 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 5 Combustion chamber 8 Exhaust port 11 Exhaust pipe 12 Fuel injection valve 13 Three-way catalyst 14 Secondary air supply device 15 Air pump 18 Control valve

Claims (4)

  A fuel supply means for supplying fuel and an oxygen supply means for supplying oxygen are provided, and the fuel supplied from the fuel supply means and the oxygen supplied from the oxygen supply means are joined at a predetermined junction. In an oxygen supply device for an internal combustion engine that reacts these fuels with oxygen and raises the temperature of the catalyst disposed in the exhaust passage with heat generated by the reaction, when the temperature of the catalyst is to be raised, A timing at which fuel is supplied from the fuel supply means so that the fuel supplied first from the fuel supply means and the oxygen supplied first from the oxygen supply means reach the predetermined joining point substantially simultaneously, and the oxygen An oxygen supply apparatus that controls at least one of timings at which supply of oxygen from a supply means is started.   The oxygen supply means includes a pump for discharging oxygen and an oxygen supply pipe for connecting the pump to an exhaust passage upstream of the catalyst at a predetermined connection point. When the temperature of the catalyst is to be increased, the pump A means for supplying oxygen to the exhaust passage upstream of the catalyst via an oxygen supply pipe, and when the temperature of the catalyst should be raised, the oxygen supplied first from the oxygen supply means reaches the predetermined confluence The timing to perform is based on at least one of the discharge pressure of the pump, the flow resistance of the oxygen supply pipe, the volume in the oxygen supply pipe from the pump to the predetermined connection point, and the pressure in the exhaust passage upstream of the catalyst. The oxygen supply device according to claim 1, wherein the oxygen supply device is estimated.   The oxygen supply device according to claim 2, wherein the pump is an air pump that discharges air.   The fuel supply means is a fuel injection valve for supplying fuel to a combustion chamber of an internal combustion engine, and when the temperature of the catalyst is to be raised, a fuel injection valve for injecting an amount of fuel larger than a normal amount; When the temperature of the catalyst should be raised, the timing at which the fuel supplied first from the fuel injection valve reaches the predetermined joining point is the amount of air sucked into the combustion chamber and the amount normal to the fuel injection valve. The oxygen supply device according to any one of claims 1 to 3, wherein the oxygen supply device is estimated based on at least one of a timing at which a command to inject a larger amount of fuel is issued.

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