JP4046062B2 - Exhaust gas recirculation control device for internal combustion engine - Google Patents

Description

  The present invention relates to an exhaust gas recirculation control device for an internal combustion engine.

  A turbocharger that drives a compressor disposed in the intake passage by a turbine disposed in the exhaust passage, an exhaust passage downstream of the turbine outlet, and an intake passage upstream of the compressor inlet (hereinafter also referred to as EGR). And a low pressure side EGR control valve is disposed in the low pressure side EGR passage, and the exhaust passage upstream of the turbine inlet and the intake passage downstream of the compressor outlet are connected by the high pressure side EGR passage and in the high pressure side EGR passage. The high-pressure side EGR control valve is disposed in the engine, the low-pressure side EGR control valve is closed during engine low-load operation, and EGR gas is supplied to the engine via the high-pressure side EGR passage. An internal combustion engine that is closed and supplies EGR gas to the engine via a low-pressure side EGR passage is known (see FIG. 17 of Patent Document 1).

  When EGR gas is supplied via the high pressure side EGR passage, the outflow end of the high pressure side EGR passage is close to the engine, so that a good response can be obtained, so that the amount of EGR gas supplied to the engine can be precisely controlled. It is preferable to supply EGR gas through the high pressure side EGR passage. However, when the engine load increases, the pressure difference between the upstream side and the downstream side of the high pressure side EGR passage becomes small, and it becomes difficult to supply a sufficient amount of EGR gas to the engine. On the other hand, when supplying EGR gas via the low pressure side EGR passage, even if the engine load increases, the pressure difference between the upstream and downstream sides of the low pressure side EGR passage does not become small, and a sufficient amount of EGR gas can be supplied.

  Therefore, in the above-described internal combustion engine, EGR gas is supplied to the engine via the high-pressure side EGR passage during low engine load operation, and EGR gas is supplied to the engine via the low-pressure side EGR passage during medium load operation.

  By the way, a large amount of fresh air must be supplied to the engine at the time of engine high load operation. For this reason, the supply of EGR gas to the engine is generally stopped. Then, in the internal combustion engine described above, EGR gas is supplied via the high pressure side EGR passage during low engine load operation, EGR gas is supplied via the low pressure side EGR passage during medium load operation, and EGR gas is supplied during high engine load operation. The supply will be stopped.

JP 2001-140703 A Japanese Patent Laid-Open No. 5-86948 Japanese Patent Laid-Open No. 5-187327

  In the above-described internal combustion engine, when the acceleration operation is performed from the low load operation in which the high pressure side EGR control valve is opened and the low pressure side EGR control valve is closed, the high pressure side EGR control valve is first set to the medium load operation. When the valve is closed and the low-pressure side EGR control valve is opened, and then the engine high load operation is started, the low-pressure side EGR control valve is closed. In this case, the low-pressure side EGR control valve is opened from the closed state and then closed again, that is, temporarily opened. Here, the time during which the low pressure side EGR control valve is opened depends on the acceleration degree of the acceleration operation. For this reason, when the rapid acceleration operation is performed, the valve opening operation and the valve closing operation of the low pressure side EGR control valve are performed in an extremely short time. As a result, the durability of the low pressure side EGR control valve is determined. May get worse.

  Further, when the low pressure side EGR control valve is opened during acceleration operation and EGR gas is supplied to the engine, a large amount of fresh air cannot be supplied to the engine, and the engine output cannot be increased rapidly. There is also a fear.

  Therefore, an object of the present invention is to provide an exhaust gas recirculation control device for an internal combustion engine that can prevent deterioration of the durability of the EGR device and ensure acceleration performance.

In order to solve the above problems, according to a first aspect of the present invention, a turbocharger that drives a compressor disposed in an intake passage by a turbine disposed in an exhaust passage is provided, and an exhaust passage upstream of the turbine inlet and the compressor are provided. An intake passage downstream of the outlet is connected by a high pressure side exhaust recirculation passage, and a high pressure side exhaust recirculation control valve is disposed in the high pressure side exhaust recirculation passage, and an exhaust passage downstream of the turbine outlet and an intake passage upstream of the compressor inlet Are connected by a low-pressure side exhaust recirculation passage, and a low-pressure side exhaust recirculation control valve is disposed in the low-pressure side exhaust recirculation passage. When the engine load is lower than the set load, the valve is closed.When the engine load is lower than the set load, the valve is closed. And opened when is high, when higher than the upper limit load is set higher than the set load is the engine load was to close the both the high pressure side exhaust gas recirculation control valve and the low pressure-side exhaust recirculation control valve In the exhaust gas recirculation control device for an internal combustion engine , the engine slow acceleration operation is performed when the engine load is lower than the set load and the high pressure exhaust gas recirculation control valve is opened and the low pressure exhaust gas recirculation control valve is closed. When the engine load is higher than the upper limit load, the low-pressure side exhaust recirculation control valve is opened or closed according to the engine load, and the engine load is lower than the set load and the high-pressure side exhaust recirculation control valve is opened. When the engine sudden acceleration operation is performed when the low-pressure side exhaust recirculation control valve is closed and the engine load becomes higher than the upper limit load, the low-pressure side exhaust recirculation control valve is kept closed. ing.

In order to solve the above-mentioned problem, according to a second aspect of the present invention, there is provided a supercharger that drives a compressor disposed in the intake passage by a turbine disposed in the exhaust passage, and the exhaust passage upstream of the turbine inlet And an intake passage downstream of the compressor outlet by a high pressure side exhaust recirculation passage, and a high pressure side exhaust recirculation control valve is disposed in the high pressure side exhaust recirculation passage, and the exhaust passage downstream of the turbine outlet and the upstream side of the compressor inlet are arranged. The low pressure side exhaust gas recirculation passage is connected to the intake passage by the low pressure side exhaust gas recirculation passage, and the low pressure side exhaust gas recirculation control valve is disposed in the low pressure side exhaust gas recirculation passage. When the engine load is lower than the first set load, the valve is opened and when the engine load is higher than the first set load, the high-pressure side exhaust gas recirculation control valve is set to the second engine load set higher than the first set load. Setting negative It closed when higher than the valve opening and the engine load is a second set load when lower than the high-pressure-side exhaust recirculation when higher than the upper limit load is set higher than the engine load is the second set load In an exhaust gas recirculation control device for an internal combustion engine in which both the control valve and the low pressure side exhaust gas recirculation control valve are closed , the engine load is lower than the first set load and the high pressure side exhaust gas recirculation control valve is opened. When the engine is accelerating and the engine load is higher than the upper limit load when the low pressure exhaust recirculation control valve is closed, the low pressure exhaust recirculation control valve is opened according to the engine load. Alternatively, when the engine load is lower than the first set load and the high pressure side exhaust gas recirculation control valve is opened and the low pressure side exhaust gas recirculation control valve is closed, the engine rapid acceleration operation is performed. When the engine load is higher than the upper limit load, And so as to hold the recirculation control valve in a closed state.

  The deterioration of the durability of the EGR device can be prevented and acceleration performance can be ensured.

  FIG. 1 shows a case where the present invention is applied to a compression ignition type internal combustion engine. However, the present invention can also be applied to a spark ignition internal combustion engine.

  Referring to FIG. 1, the engine body 1 has, for example, four cylinders 1a. Each cylinder 1 a is connected to a common surge tank 3 via a corresponding intake branch pipe 2, and the surge tank 3 is connected to an outlet of a compressor 6 of an exhaust turbocharger 5 via an intake duct 4. An intake pipe 4 a is connected to the inlet of the compressor 6. A throttle valve 8H driven by a step motor 7H is arranged in the intake duct 4, and a throttle valve 8L driven by a step motor 7L is arranged in the intake pipe 4a. Further, a cooling device 9 for cooling the intake air flowing through the intake duct 4 is disposed around the intake duct 4.

  On the other hand, each cylinder 1 a is connected to the inlet of the exhaust turbine 12 of the exhaust turbocharger 5 via the exhaust manifold 10 and the exhaust pipe 11, and the outlet of the exhaust turbine 12 is connected to the catalytic converter 14 via the exhaust pipe 13. An exhaust pipe 13 a is connected to the catalytic converter 14.

  Fuel injection valves 15 are arranged in the cylinders of the respective cylinders 1 a, and these fuel injection valves 15 are connected to an electrically controlled fuel pump 17 having a variable discharge amount via a common rail 16. The suction port of the fuel pump 17 is connected to the fuel tank 18. A fuel pressure sensor (not shown) for detecting the fuel pressure in the common rail 16 is attached to the common rail 16 so that the fuel pressure in the common rail 16 becomes the target fuel pressure based on the output signal of the fuel pressure sensor. In addition, the discharge amount of the fuel pump 17 is controlled.

  The exhaust manifold 10 and the surge tank 3 are connected to each other via a high pressure side EGR passage 19H, and an electrically controlled high pressure side EGR control valve 20H is disposed in the high pressure side EGR passage 19H. Around the high pressure side EGR passage 19H, a cooling device 21H for cooling the EGR gas flowing in the high pressure side EGR passage 19H is arranged. On the other hand, the exhaust pipe 13a downstream of the catalytic converter 14 and the intake pipe 4a downstream of the throttle valve 8L are connected to each other via a low pressure side EGR passage 19L, and an electrically controlled low pressure side EGR control valve is provided in the low pressure side EGR passage 19L. 20L is arranged. A cooling device 21L for cooling the EGR gas flowing in the low pressure side EGR passage 19L is disposed around the low pressure side EGR passage 19L.

  The electronic control unit 30 is composed of a digital computer, and is connected to each other by a bidirectional bus 31. A ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, and a backup RAM (B-RAM). 35, an input port 36 and an output port 37. An air flow meter 40 for detecting the amount of intake air is attached to the intake pipe 4a upstream of the throttle valve 8L, and an output signal of the air flow meter 40 is input to the input port 36 via the corresponding AD converter 38. An accelerator pedal (not shown) is connected to a depression amount sensor 41 that generates an output voltage proportional to the depression amount of the accelerator pedal. The output voltage of the depression amount sensor 41 is input to the input port via the corresponding AD converter 38. 36. The amount of depression of the accelerator pedal represents the engine load L. Further, a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 10 ° is connected to the input port 36. The CPU 34 calculates the engine speed N based on the output pulse from the crank angle sensor 42. On the other hand, the output port 37 is connected to the stepping motors 7H and 7L, the fuel injection valve 15, the fuel pump 17, the high-pressure side EGR control valve 20H, and the low-pressure side EGR control valve 20L through corresponding drive circuits 39, respectively.

  In the internal combustion engine shown in FIG. 1, EGR gas can be supplied to the engine via the high-pressure side EGR passage 19H, or can be supplied via the low-pressure side EGR passage 19L. When supplying the EGR gas via the high-pressure side EGR passage 19H, good responsiveness can be ensured, and therefore the amount of EGR gas supplied to the engine can be precisely controlled. However, when the engine load becomes high, the pressure difference between the upstream and downstream sides of the high pressure side EGR passage 19H becomes small, so that it becomes difficult to supply a sufficient amount of EGR gas to the engine. On the other hand, when supplying EGR gas via the low pressure side EGR passage 19L, the pressure difference between the upstream and downstream sides of the low pressure side EGR passage 19L is not reduced even when the engine load increases, and a sufficient amount of EGR gas is supplied. Can do.

  Therefore, in the first embodiment according to the present invention, when the engine load L is lower than the predetermined set load LS (N), EGR gas is supplied only through the high pressure side EGR passage 19H, and the engine load L is set to the set load LS. When it is higher than (N), the EGR gas is supplied only through the low pressure side EGR passage 19L.

  However, when the engine load L is higher than the upper limit load LU (N) set higher than the set load LS (N), the supply of EGR gas to the engine is stopped in order to supply a large amount of fresh air to the engine. Is done.

  In summary, as shown in FIG. 2, when the engine load L is lower than the set load LS (N) and therefore the engine operating state is in the first region I, the low pressure side EGR control valve 20L is closed and the high pressure is increased. The side EGR control valve 20H is opened, and EGR gas is supplied to the engine only through the high pressure side EGR passage 19H. The opening degree DH of the high pressure side EGR control valve 20H in this case is stored in advance in the ROM 32 in the form of a map shown in FIG. 3A as a function of the engine operating state, for example, the engine load L and the engine speed N.

  On the other hand, when the engine load L is higher than the set load LS (N) and lower than the upper limit load LU (N) and therefore the engine operating state is in the second region II, the high pressure side EGR control valve 20H is closed and the low pressure side The EGR control valve 20L is opened, and EGR gas is supplied to the engine only through the low-pressure side EGR passage 19L. The opening DL of the low pressure side EGR control valve 20L in this case is stored in advance in the ROM 32 in the form of a map shown in FIG. 3B as a function of the engine operating state, for example, the engine load L and the engine speed N.

  When the engine load L is higher than the upper limit load LU (N) and therefore the engine operating state is in the third region III, the high-pressure side EGR control valve 20H and the low-pressure side EGR control valve 20L are closed, and EGR gas to the engine Is stopped.

  Each grid point indicated by a black circle in FIGS. 3 (A) and 3 (B) represents a point at which the opening degree DH, DL is set, and the opening degree DH, DL is calculated by interpolation between the lattice points. Is done. The set load LS (N) and the upper limit load LU (N) are stored in advance in the ROM 32 in the form of a map shown in FIG.

  Thus, the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L are controlled in accordance with the region to which the engine operating state belongs. Accordingly, when the engine acceleration operation is performed and the engine operation state shifts from the first region I to the second region II as indicated by an arrow A in FIG. 4, for example, the high pressure side EGR control valve 20H is changed from being opened to being closed. The low pressure side EGR control valve 20L is switched from the closed valve to the opened valve.

  On the other hand, when the engine operating state shifts from the first region I to the third region III as indicated by the arrow B in FIG. 4, the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L are as follows. Is controlled.

  FIG. 5 (A) shows a case where the engine slow acceleration operation is performed. Referring to FIG. 5A, when the engine slow acceleration operation is started as indicated by an arrow X, the engine load L starts to increase. At this time, the high-pressure side EGR control valve 20H is held in the open state and the low-pressure side. The EGR control valve 20L is held in a closed state. Next, as indicated by an arrow Y, when the engine load L becomes higher than the set load LS (N) and the engine operating state shifts to the second region II, the high pressure side EGR control valve 20H is closed and the low pressure side EGR control valve. 20L is opened. Next, when the engine load L becomes higher than the upper limit load LU (N) as indicated by the arrow Z and the engine operating state shifts to the third region III, the low pressure side EGR control valve 20L is closed, and thus EGR. Gas supply is stopped.

  On the other hand, referring to FIG. 5B showing the case where the engine rapid acceleration operation is performed, when the engine rapid acceleration operation is started as indicated by the arrow X, the high pressure side EGR control valve 20H is closed. The At this time, since the low pressure side EGR control valve 20L is also closed, the supply of the EGR gas to the engine is stopped. Next, as shown by the arrow Y, even if the engine load L becomes higher than the set load LS (N) and the engine operating state shifts to the second region II, the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L. Is kept closed, and the supply of EGR gas continues to be stopped. Next, even if the engine load L becomes higher than the upper limit load LU (N) as indicated by the arrow Z and the engine operating state shifts to the third region III, the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L. Is kept closed, and the supply of EGR gas continues to be stopped. This is done for the following reason.

  In the example shown in FIG. 5A, the low pressure side EGR control valve 20L is opened only for time t, and this time t depends on the acceleration degree of acceleration operation. Therefore, as described at the beginning, when the rapid acceleration operation is performed, the low pressure side EGR control valve 20L is opened and closed in a very short time, and as a result, the low pressure side EGR control is performed. The durability of the valve 20L may be deteriorated. Further, when the low pressure side EGR control valve 20L is opened during acceleration operation and EGR gas is supplied to the engine, a large amount of fresh air cannot be supplied to the engine, and the engine output can be increased rapidly. There is also a risk of disappearing.

  Therefore, in the first embodiment according to the present invention, when the engine load L is lower than the set load LS (N) and the high pressure side EGR control valve 20H is opened and the low pressure side EGR control valve 20L is closed, the engine sudden acceleration is performed. When the operation is performed and the engine load L becomes higher than the upper limit load LU (N), the low-pressure side EGR control valve 20L is kept closed. As a result, it is possible to prevent the durability of the low pressure side EGR control valve 20L from deteriorating and to ensure acceleration performance. Whether the slow acceleration operation or the rapid acceleration operation is being performed can be determined based on, for example, the changing speed of the engine load L.

  FIG. 6 shows an EGR control routine of the first embodiment according to the present invention. This routine is executed by interruption every predetermined time.

  Referring to FIG. 6, first, at step 100, it is judged if the engine rapid acceleration operation is being performed. When the engine rapid acceleration operation is not performed, that is, when the slow acceleration operation or the steady operation is performed, the process proceeds to step 101, and the upper limit load LU (N) is calculated from the map of FIG. In the following step 102, it is determined whether or not the engine load L is lower than the upper limit load LU (N). When L <LU (N), the routine proceeds to step 103 where the set load LS (N) is calculated from the map of FIG. In the following step 104, it is determined whether or not the engine load L is lower than the set load LS (N). When L <LS (N), that is, when the engine operating state is in the first region I, the routine proceeds to step 105 where the opening DL of the low pressure side EGR control valve 20L is made zero, that is, the low pressure side EGR control valve 20L. Is closed. In the subsequent step 106, the opening degree DH of the high pressure side EGR control valve 20H is calculated from the map of FIG. On the other hand, when L ≧ LS (N), that is, when the engine operating state is in the second region II, the routine proceeds from step 104 to step 107, and the opening DL of the low pressure side EGR control valve 20L from the map of FIG. Is calculated. At the next step 108, the opening degree DH of the high pressure side EGR control valve 20H is made zero, that is, the high pressure side EGR control valve 20H is closed.

  When L ≧ LU (N), that is, when the engine operating state is in the third region III, the routine proceeds from step 102 to step 109, where the opening DL of the low-pressure side EGR control valve 20L and the opening of the high-pressure side EGR control valve 20H Both DH are set to zero.

  On the other hand, when the rapid acceleration operation is being performed, the routine proceeds from step 100 to step 109, where both the opening DL of the low pressure side EGR control valve 20L and the opening DH of the high pressure side EGR control valve 20H are made zero. The low-pressure side EGR control valve 20L and the high-pressure side EGR control valve 20H are controlled so that the respective opening degrees coincide with the calculated opening degrees DL and DH.

  Next, a second embodiment according to the present invention will be described with reference to FIG.

  In the second embodiment according to the present invention, four regions are provided as shown in FIG. In the first region I where the engine load L is lower than the first set load LS1 (N), the high pressure side EGR control valve 20H is opened and the low pressure side EGR control valve 20L is closed.

  In the second region II where the engine load L is higher than the second set load LS2 (N) set higher than the first set load LS1 (N) and lower than the upper limit load LU (N), the low pressure side EGR The control valve 20L is opened and the high pressure side EGR control valve 20H is closed. In the third region III in which the engine load L is higher than the upper limit load LU (N), both the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L are closed.

  In the fourth region IV where the engine load L is higher than the first set load LS1 (N) and lower than the second set load LS2 (N), both the high pressure side EGR control valve 20H and the low pressure side EGR control valve 20L are used. Is opened. The first set load LS1 (N), the second set load LS2 (N), and the upper limit load LU (N) are stored in advance in the ROM 32 as a function of the engine speed N in the form of a map shown in FIG. Is remembered.

  In other words, the high pressure side EGR control valve 20H is opened when the engine load L is lower than the second set load LS2 (N) and closed when the engine load L is higher than the second set load LS2 (N). The low-pressure side EGR control valve 20L is opened when the engine load L is lower than the first set load LS1 (N), and the engine load L is higher than the first set load LS1 (N) and the second This means that the valve is open when it is lower than the set load LS2 (N).

  The opening degree DH of the high-pressure side EGR control valve 20H in this case is stored in the ROM 32 in advance in the form of a map shown in FIG. 8A as a function of the engine operating state, for example, the engine load L and the engine speed N, The opening DL of the low pressure side EGR control valve 20L is also stored in advance in the ROM 32 in the form of a map shown in FIG. 8B as a function of the engine operating state, for example, the engine load L and the engine speed N.

  Here, the first set load LS1 (N) is lower than the set load LS (N) of the first embodiment according to the present invention, and the second set load LS2 (N) is higher than the set load LS (N). Can be set. That is, compared with the first embodiment according to the present invention, the operating range in which the high pressure side EGR control valve 20H is opened is expanded to the low load side, and the operating range in which the low pressure side EGR control valve 20L is opened is a high load. Can be enlarged to the side.

  Also in the second embodiment according to the present invention, when the engine operating state is shifted from the first region I to the third region III by the engine rapid acceleration operation, the low pressure side EGR control valve 20L is held in the closed state.

  On the other hand, when the engine operating state is shifted from the first region I to the third region III in the engine slow acceleration operation, the low pressure side EGR control valve 20L is sequentially opened, and the high pressure side EGR control valve 20H. Is closed, and the low-pressure side EGR control valve 20L is closed.

  FIG. 9 shows an EGR control routine of the second embodiment according to the present invention. This routine is executed by interruption every predetermined time.

  Referring to FIG. 9, first, at step 120, it is judged if the engine rapid acceleration operation is being performed. When the engine rapid acceleration operation is not performed, the routine proceeds to step 121, where the upper limit load LU (N) is calculated from the map of FIG. In the following step 122, it is determined whether or not the engine load L is lower than the upper limit load LU (N). When L <LU (N), the routine proceeds to step 123 where the first set load LS1 (N) is calculated from the map of FIG. In the following step 124, it is determined whether or not the engine load L is lower than the first set load LS1 (N). When L <LS1 (N), that is, when the engine operating state is in the first region I, the routine proceeds to step 125, where the opening degree DL of the low pressure side EGR control valve 20L is made zero. Next, the routine proceeds to step 127. On the other hand, when L ≧ LS1 (N), that is, when the engine operating state is in the second region II or the fourth region IV, the routine proceeds to step 126, where the low pressure side EGR control valve is determined from the map of FIG. The opening DL of 20 L is calculated. Next, the routine proceeds to step 127.

  In step 127, the second set load LS2 (N) is calculated from the map of FIG. In the following step 128, it is determined whether or not the engine load L is lower than the second set load LS2 (N). When L <LS2 (N), that is, when the engine operating state is in the first region I or the fourth region IV, the routine proceeds to step 129, where the opening degree of the high pressure side EGR control valve 20H is determined from the map of FIG. DH is calculated. On the other hand, when L ≧ LS2 (N), that is, when the engine operating state is in the second region II, the routine proceeds to step 130 where the opening degree DH of the high pressure side EGR control valve 20H is made zero.

  When L ≧ LU (N), that is, when the engine operating state is in the third region III, the routine proceeds from step 122 to step 131, where the opening DL of the low-pressure side EGR control valve 20L and the opening of the high-pressure side EGR control valve 20H Both DH are set to zero.

  On the other hand, when the rapid acceleration operation is being performed, the routine proceeds from step 120 to step 131, where both the opening DL of the low pressure side EGR control valve 20L and the opening DH of the high pressure side EGR control valve 20H are made zero.

  Since other configurations and operations of the second embodiment according to the present invention are the same as those of the first embodiment according to the present invention, the description thereof is omitted.

1 is an overall view of an internal combustion engine. It is a diagram which shows setting load LS (N) and upper limit load LU (N). It is a diagram which shows the opening degree of a high pressure side EGR control valve and a low pressure side EGR control valve. It is a figure explaining the change of an engine operating state. It is a time chart for demonstrating 1st Example by this invention. It is a flowchart which shows the EGR control routine of 1st Example by this invention. FIG. 4 is a diagram showing a first set load LS1 (N), a second set load LS2 (N), and an upper limit load LU (N). It is a diagram which shows the opening degree of a high pressure side EGR control valve and a low pressure side EGR control valve. It is a flowchart which shows the EGR control routine of 2nd Example by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine body 3 ... Surge tank 4a ... Intake pipe 5 ... Exhaust turbocharger 6 ... Turbine 10 ... Exhaust manifold 12 ... Compressor 13a ... Exhaust pipe 19H ... High pressure side EGR passage 19L ... Low pressure side EGR passage 20H ... High pressure side EGR control valve 20L ... Low pressure side EGR control valve 41 ... Depression amount sensor

Claims (2)

A turbocharger that drives a compressor disposed in the intake passage by a turbine disposed in the exhaust passage, and connects the exhaust passage upstream of the turbine inlet and the intake passage downstream of the compressor outlet by a high-pressure side exhaust recirculation passage. And a high pressure side exhaust recirculation control valve is disposed in the high pressure side exhaust recirculation passage, and the exhaust passage downstream of the turbine outlet and the intake passage upstream of the compressor inlet are connected by the low pressure side exhaust recirculation passage. A low-pressure side exhaust recirculation control valve is arranged in the exhaust gas recirculation passage, and the high-pressure side exhaust gas recirculation control valve is opened when the engine load is lower than a predetermined set load, and the engine load is higher than the set load. closed when, and opens when closed and the engine load when the lower than the engine load and the low-pressure-side exhaust recirculation control valve is set load is higher than the set load, than the set load is the engine load In the exhaust recirculation control system for an internal combustion engine which is adapted to close both the high pressure side exhaust gas recirculation control valve and the low pressure-side exhaust recirculation control valve when Ku above the set limit load, the engine load is set Load When the engine load is higher than the upper limit load when the engine load is higher than the upper limit load when the low pressure exhaust recirculation control valve is open and the low pressure exhaust recirculation control valve is closed When the recirculation control valve is opened or closed according to the engine load , the engine load is lower than the set load, the high pressure exhaust recirculation control valve is opened, and the low pressure exhaust recirculation control valve is closed An exhaust gas recirculation control device for an internal combustion engine that keeps the low pressure side exhaust gas recirculation control valve closed when the engine sudden acceleration operation is performed and the engine load becomes higher than the upper limit load. A turbocharger that drives a compressor disposed in the intake passage by a turbine disposed in the exhaust passage, and connects the exhaust passage upstream of the turbine inlet and the intake passage downstream of the compressor outlet by a high-pressure side exhaust recirculation passage. And a high pressure side exhaust recirculation control valve is disposed in the high pressure side exhaust recirculation passage, and the exhaust passage downstream of the turbine outlet and the intake passage upstream of the compressor inlet are connected by the low pressure side exhaust recirculation passage. A low-pressure side exhaust recirculation control valve is disposed in the exhaust gas recirculation passage, and the low-pressure side exhaust recirculation control valve is closed when the engine load is lower than the first set load, and the engine load is higher than the first set load. When the engine load is higher than the first set load, the high pressure side exhaust gas recirculation control valve is opened when the engine load is lower than the second set load set higher than the first set load. Than load Closed when high, so as to close the both the high pressure side exhaust gas recirculation control valve and the low pressure-side exhaust recirculation control valve when higher than high set upper limit load than the engine load is the second set load When the engine load is lower than the first set load and the high-pressure side exhaust recirculation control valve is opened and the low-pressure side exhaust recirculation control valve is closed, When slow acceleration operation is performed and the engine load becomes higher than the upper limit load, the low pressure side exhaust recirculation control valve is opened or closed according to the engine load , and the engine load is lower than the first set load and the high pressure side When the exhaust gas recirculation control valve is opened and the low pressure exhaust gas recirculation control valve is closed, the engine sudden acceleration operation is performed and the engine load becomes higher than the upper limit load. Internal combustion engine designed to keep valve closed Exhaust gas recirculation control device.

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