JP5598376B2 - Internal combustion engine device - Google Patents

Description

  The present invention relates to an internal combustion engine device in which supercharged air is provided in an intake passage.

  Conventionally, a throttle valve for adjusting the amount of intake air supplied to the combustion chamber is arranged upstream of the supercharger in the intake passage, and the EGR device passage for returning exhaust gas is connected between the throttle valve and the supercharger. In such an internal combustion engine device, a technique for preventing the pressure upstream of the supercharger from excessively decreasing has been proposed.

  As an example of this technique, the minimum opening of the EGR valve and throttle valve for adjusting the amount of exhaust gas returned to the intake passage by the EGR device and the drive delay time are set based on the intake air amount (for example, patents). Reference 1).

JP 2008-133787 A

  However, in the technique disclosed in Patent Document 1, the minimum opening degree of the EGR valve and the throttle valve for adjusting the amount of exhaust gas returned to the intake passage by the EGR device based on the intake air amount and the delay time of driving are set. Therefore, it is not directly based on the negative pressure acting on the portion between the supercharger and the throttle valve in the intake passage.

  In the technique of the cited document 1, since it is not directly based on the estimated value of the negative pressure acting upstream of the supercharger in the intake passage, the EGR valve or the throttle valve opening becomes excessive, and the flow rate of exhaust gas returned to the intake passage Is lacking. As a result, the burden on the supercharger increases.

  An object of the present invention is to provide an internal combustion engine device capable of reducing a burden on a supercharger while maintaining an optimal operating state of the internal combustion engine.

  An internal combustion engine device according to claim 1 is an internal combustion engine, an intake passage connected to the internal combustion engine, a supercharger provided in the intake passage, and upstream of the supercharger in the intake passage. A throttle valve, a restriction opening calculation means, a target opening calculation means, and a valve driving means are provided.

The limit opening calculation means detects the pressure upstream of the throttle valve in the intake passage, the temperature of air flowing upstream of the throttle valve in the intake passage, and the amount of intake air, and sets these values. Based on this, the throttle valve limit opening at which the pressure acting on the portion between the supercharger and the throttle valve in the intake passage becomes a predetermined value is calculated.

  The target opening calculation means compares the throttle valve limit opening calculated by the limit opening calculation means with the optimum throttle valve opening determined according to the state of the internal combustion engine, When the optimum opening is equal to or greater than the limit opening, the target opening that is the target value of the opening of the throttle valve is set as the optimum opening, and when the optimum opening is less than the limit opening, the target The opening is defined as the limit opening. The valve drive means opens and closes the throttle valve based on the detection result of the target opening degree calculation means.

The operations of the limit opening calculating means, the target opening calculating means, and the valve driving means are repeatedly executed during driving of the internal combustion engine.

According to a second aspect of the invention, there is provided the internal combustion engine device according to the first aspect , wherein the predetermined value of the pressure acting on a portion between the supercharger and the throttle valve is the rotational speed of the internal combustion engine. , Based on the load of the internal combustion engine.

  ADVANTAGE OF THE INVENTION According to this invention, the burden on a supercharger can be made small, maintaining the optimal driving | running state of an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows a motor vehicle provided with the internal combustion engine apparatus which concerns on the 1st this embodiment of this invention. Schematic which shows the vicinity of the throttle valve apparatus for low pressure EGR in the internal combustion engine apparatus shown by FIG. The flowchart which shows operation | movement of engine ECU shown by FIG. The flowchart which shows operation | movement of engine ECU shown by FIG. Sectional drawing of the intake passage shown along the F5-F5 line shown in FIG. The map which shows the limit opening area corresponding to the opening limit of the throttle valve of the throttle valve device for low pressure EGR shown in FIG. The graph which shows the optimal opening degree of the throttle-valve apparatus for low pressure EGR shown in FIG. The graph which shows the negative pressure value which acts between a throttle valve and a 1st part in an intake passage when the optimal opening degree shown by FIG. 7 is made into a target opening degree. The graph which shows the restriction | limiting opening degree in the driving | running state of the motor vehicle shown by FIG. The graph which shows the target opening degree obtained as a result of comparing the optimal opening degree shown by FIG. 7, and the limiting opening degree shown by FIG. The graph which shows the negative pressure value which acts on the part between a throttle valve and a 1st part in an intake passage when controlling a valve drive part so that it may become the target opening degree shown in FIG. The map which shows the limit negative pressure value of the internal combustion engine apparatus which concerns on the 2nd Embodiment of this invention.

  An internal combustion engine device according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view showing an automobile 1 including an internal combustion engine device 10 of the present embodiment. In FIG. 1, an internal combustion engine device 10 is schematically shown. As shown in FIG. 1, the automobile 1 includes an internal combustion engine device 10, a pair of front wheels 2, a pair of rear wheels 3, an accelerator pedal 4, an accelerator sensor 5, and a main ECU 6. In addition, the automobile 1 includes a transmission mechanism (not shown) that transmits a driving force generated by a diesel engine 20 included in an internal combustion engine device 10 described later to the front wheels 2. The automobile 1 can travel by the driving force generated by the diesel engine 20.

  The accelerator pedal 4 is a pedal that the driver steps on when driving the vehicle. The accelerator sensor 5 detects the amount of depression of the accelerator pedal 4. The accelerator sensor 5 is connected to the main ECU 6. The accelerator sensor 5 transmits the detection result to the main ECU 6.

  The main ECU 6 performs various controls of the automobile 1. Based on the detection result of the accelerator sensor 5, the main ECU 6 transmits an output request to an engine ECU 60 described later.

  As shown in FIG. 1, the internal combustion engine device 10 includes a diesel engine 20, an intake system 30, an exhaust system 40, a turbocharger 50, and an engine ECU 60.

  The diesel engine 20 is an example of an internal combustion engine referred to in the present invention. The diesel engine 20 is a reciprocating type and has four cylinders. Each of the combustion chambers 21a, 21b, 21c, and 21d of the diesel engine 20 is provided with injectors 22a, 22b, 22c, and 22d that inject fuel. The injectors 22a to 22d are connected to the common rail 23. The common rail 23 boosts the fuel.

  The turbocharger 50 is an example of a supercharger referred to in the present invention. The turbocharger 50 includes a first portion 51 provided in an intake passage described later, and a second portion 55 provided in an exhaust passage described later.

  The intake system 30 guides air A or an air-fuel mixture M of air A and exhaust H to the diesel engine 20. The intake system 30 includes an intake passage 31, an air cleaner 32, an air flow sensor 33, a low pressure EGR throttle valve device 34, a first portion 51 of a turbocharger 50, an intercooler 35, and a high pressure EGR throttle valve device. 36 and a boost sensor 37 are provided.

  In the intake passage 31, air A or an air-fuel mixture M of air A and exhaust H flows. The intake passage 31 includes an intake passage main body 31a and an intake manifold 31b. The intake manifold 31 b communicates with the combustion chambers 21 a to 21 d of the diesel engine 20. The intake passage body 31a is connected to the intake manifold 31b. The intake passage body 31a communicates with the intake manifold 31b. The intake passage main body 31a referred to here indicates a portion other than the intake manifold 31b in the intake passage 31.

  The air cleaner 32 is provided in the intake passage 31. The air cleaner 32 filters air A introduced from the outside. The air flow sensor 33 is provided downstream of the air cleaner 32 in the intake passage 31. The air flow sensor 33 detects the amount of intake air flowing through the intake passage 31. The air flow sensor 33 has a function of detecting the temperature of the air A. The intake air amount is the mass of air flowing per unit time, that is, per second. The unit is (kg / sec).

  The low-pressure EGR throttle valve device 34 is provided downstream of the air flow sensor 33 in the intake passage 31. The low-pressure EGR throttle valve device 34 includes a throttle valve 34a disposed in the intake passage 31 and a valve drive unit 34b that changes the attitude of the throttle valve 34a in the intake passage 31 by rotating the throttle valve 34a. I have. As an example, the throttle valve 34a is a butterfly valve. By changing the attitude of the throttle valve 34a in the intake passage 31, the amount of air A passing through the low pressure EGR throttle valve device 34 is adjusted.

  Here, the opening degree of the throttle valve device 34 for low pressure EGR will be described. FIG. 2 shows the vicinity of the low-pressure EGR throttle valve device 34 in the internal combustion engine device 10. In FIG. 2, the throttle valve 34a when the opening degree of the throttle valve device 34 for low pressure EGR is the minimum is shown by a solid line, and the throttle valve 34a when the opening degree is the maximum is shown by a two-dot chain line. As shown in FIG. 2, the state where the opening degree of the low pressure EGR throttle valve device 34 is the minimum is a state where the intake passage 31 is closed by the throttle valve 34a. For this reason, the air A does not pass through the low-pressure EGR throttle valve device 34. The state in which the opening degree is maximum is a state in which the throttle valve 34a has the least flow resistance, and the intake passage 31 is most open in the direction in which the air A passes through the low-pressure EGR throttle valve device 34.

  The opening degree is determined in accordance with the rotation angle of the throttle valve 34a. The rotation angle referred to here is a rotation angle based on a state where the opening degree is minimum. In other words, the attitude of the throttle valve 34a. As the rotation angle increases, the opening degree increases. The valve drive unit 34b includes a sensor that detects a rotation angle of the throttle valve 34a based on a state where the opening degree is the minimum. In addition to the valve drive unit 34b, a means for detecting the rotation angle that is the attitude of the throttle valve 34a may be provided.

  The engine ECU 60 described later includes information indicating the opening degree of the low-pressure EGR throttle valve device 34 corresponding to the rotation angle of the throttle valve 34a in advance.

  The first portion 51 of the turbocharger 50 is provided downstream of the low pressure EGR throttle valve device 34 in the intake passage 31. The first portion 51 includes a compressor wheel 52 and a first housing 53 that houses the compressor wheel 52 and forms a part of the intake passage 31. A shaft 54 is fixed to the compressor wheel 52. The compressor wheel 52 is supported in the first housing 53 so as to be rotatable around the shaft 54. In the first housing 53, a bearing structure (not shown) that supports the shaft 54 is provided.

  The intercooler 35 is provided downstream of the first portion 51 in the intake passage 31.

  The high pressure EGR throttle valve device 36 is provided in the intake passage 31 downstream of the intercooler 35 and upstream of the intake manifold 31b. The structure of the high pressure EGR throttle valve device 36 is the same as that of the low pressure EGR throttle valve device 34. The high pressure EGR throttle valve device 36 includes a throttle valve 36a and a valve drive unit 36b. The throttle valve 36a and the valve driving unit 36b are the same as the throttle valve 34a and the valve driving unit 34b of the throttle valve device 34 for low pressure EGR. The opening of the throttle valve 36a is the same as the opening of the throttle valve device 34 for low pressure EGR.

  The boost sensor 37 detects the pressure in the intake manifold 31b.

  The exhaust system 40 guides the exhaust H discharged from the combustion chambers 21a to 21d to the outside. The exhaust system 40 includes an exhaust passage 41, a second portion 55 of the turbocharger 50, a catalyst device 42, a low pressure EGR (Exhaust Gas Recirculation) device 70, and a high pressure EGR device 80.

  In the exhaust passage 41, exhaust H discharged from the combustion chambers 21a to 21d of the diesel engine 20 flows. The exhaust passage 41 includes an exhaust passage main body 41a and an exhaust manifold 41b. The exhaust manifold 41b communicates with the combustion chambers 21a to 21d. The exhaust passage main body 41a communicates with the exhaust manifold 41b. The exhaust passage main body 41a indicates a portion of the exhaust passage 41 other than the exhaust manifold 41b.

  The second portion 55 of the turbocharger 50 is provided in the exhaust passage main body 41a. The second portion 55 includes a turbine wheel 56 and a second housing 57 that accommodates the turbine wheel 56 and forms a part of the exhaust passage 41. The turbine wheel 56 is fixed to the shaft 54 and is rotatable around the shaft 54. That is, the turbine wheel 56 and the compressor wheel 52 rotate integrally. When the turbine wheel 56 rotates due to the exhaust H flowing, the compressor wheel 52 also rotates. A bearing structure (not shown) that supports the shaft 54 is provided in the second housing 57.

  The catalyst device 42 is provided downstream of the second portion 55 in the exhaust passage 41. The catalyst device 42 includes an oxidation catalyst 42a and a DPF (Diesel Particulate Filter) 42b. The oxidation catalyst 42a is located upstream of the DPF 42b.

  The low pressure EGR device 70 includes a low pressure EGR passage 71, a low pressure EGR cooler 72, and a low pressure EGR valve 73. One end 74 of the low pressure EGR passage 71 communicates with the downstream side of the catalyst device 42 in the exhaust passage 41. The other end 75 of the low pressure EGR passage 71 communicates between the first portion 51 and the throttle valve 34 a in the intake passage 31. The low pressure EGR passage 71 communicates the exhaust passage 41 and the intake passage 31. The low pressure EGR cooler 72 is provided in the low pressure EGR passage 71. The low pressure EGR valve 73 is provided downstream of the low pressure EGR cooler 72 in the low pressure EGR passage 71. The low pressure EGR valve 73 opens and closes the low pressure EGR passage 71.

  The high pressure EGR device 80 includes a high pressure EGR passage 81, a high pressure EGR cooler 82, and a high pressure EGR valve 83. One end 84 of the high pressure EGR passage 81 communicates with the upstream of the second portion 55 of the turbocharger 50 in the exhaust passage 41. The other end 85 of the high pressure EGR passage 81 communicates with the downstream side of the throttle valve 36 a in the intake passage 31. The high pressure EGR passage 81 communicates the exhaust passage 41 and the intake passage 31.

  The high pressure EGR cooler 82 is provided in the high pressure EGR passage 81. The high pressure EGR valve 83 is provided downstream of the high pressure EGR cooler 82 in the high pressure EGR passage 81. The high pressure EGR valve 83 opens and closes the high pressure EGR passage 81.

  The engine ECU 60 is connected to the boost sensor 37 and the air flow sensor 33. Boost sensor 37 and airflow sensor 33 transmit the detection result to engine ECU 60.

  The engine ECU 60 is connected to the main ECU 6 and receives an operation instruction from the main ECU 6. The engine ECU 60 is connected to the valve drive unit 34 b of the low pressure EGR throttle valve device 34, the valve drive unit 36 b of the high pressure EGR throttle valve device 36, the low pressure EGR valve 73, and the high pressure EGR valve 83. Control the opening and closing of these valves. The engine ECU 60 controls the operations of the injectors 23a to 23d.

  Specifically, the main ECU 6 issues an output request to the engine ECU 60 based on the detection result of the accelerator sensor 5. The engine ECU 60 is based on an instruction from the main ECU 6 or according to an operating state of the diesel engine 20, a low pressure EGR throttle valve device 34, a high pressure EGR throttle valve device 36, a low pressure EGR valve 73, The operation of the high pressure EGR valve 83 and the injectors 23a to 23d is controlled. The control of the operation of the throttle valve device 34 for low pressure EGR by the engine ECU 60 will be specifically described later.

  The engine ECU 60 includes information indicating the opening degree of the low pressure EGR throttle valve device 34 corresponding to the rotation angle of the throttle valve 34a of the low pressure EGR throttle valve device 34 in advance. Similarly, information indicating the opening degree of the throttle valve 36a corresponding to the rotation angle of the throttle valve 36a of the high-pressure EGR throttle valve device 36 is provided.

  In FIG. 1, connection lines that indicate connections between the injectors 23 a to 23 d and the engine ECU 60 are partially omitted.

  Next, the operation for determining the opening degree of the throttle valve device 34 for low pressure EGR will be described. FIG. 3 is a flowchart showing the operation of the engine ECU 60. The engine ECU 60 is driven when the electric system of the automobile 1 is turned on. In other words, when the main ECU 6 starts operating, the operation starts.

  In step ST1, the engine ECU 60 determines whether or not the diesel engine 20 is being driven. The state in which the diesel engine 20 is driven is a state in which fuel is injected from the injectors 23a to 23d. An instruction to start driving the diesel engine 20 is transmitted from the main ECU 6 to the engine ECU 60. When the engine ECU 60 receives an instruction to start driving the diesel engine 20 from the main ECU 6, the process proceeds to step ST2.

  In step ST2, the engine ECU 60 detects the optimum opening degree of the low pressure EGR throttle valve device 34. The optimum opening referred to here is an example of the optimum opening referred to in the present invention. The optimal opening is an optimal opening in order to improve the drivability of the automobile and to suppress deterioration of the exhaust components. The engine ECU 60 detects the optimum opening based on the information from the main ECU 6, the detection result of the boost sensor 37, and the like. When the optimum opening is detected, the process proceeds to step ST3.

  In step ST3, the engine ECU 60 detects the limit opening degree of the low pressure EGR throttle valve device 34. The limit opening referred to here is an example of the limit opening referred to in the present invention. The limit opening is an opening that does not cause a problem in a portion provided in the intake passage in the supercharger referred to in the present invention.

  The malfunction which arises in the part provided in an intake passage in a supercharger is demonstrated concretely. The first portion 51 is an example of a portion provided in the intake passage in the supercharger. A low pressure EGR throttle valve device 34 is provided upstream of the first portion 51. Depending on the opening of the throttle valve device 34 for low pressure EGR, the pressure in the portion between the throttle valve 34 a and the first portion 51 in the intake passage 31 may be less than the pressure downstream of the first portion 51 in the intake passage 31. Negative pressure. When a negative pressure is reached, this negative pressure acts on the first portion 51.

  More specifically, when the pressure in the portion between the throttle valve 34 a and the first portion 51 in the intake passage 31 becomes negative with respect to the pressure downstream of the first portion 51 in the intake passage 31. The load is applied to the compressor wheel 52 and the shaft 54. Further, the lubricating oil that lubricates the bearing mechanism that supports the shaft 54 provided in the first housing 53 may be sucked out. These are examples of the above unspecified.

  Returning to the description of step ST3. FIG. 4 is a flowchart showing the operation of step ST3 more specifically. As shown in FIG. 4, the process proceeds to step ST31 after step ST2.

  In step ST31, the engine ECU 60 detects the temperature T1, the intake air amount G, and the pressure P1 of the intake air A passing through the low pressure EGR throttle valve device 34. Since the intake air amount G and the temperature T1 are transmitted from the air flow sensor 33, they can be obtained.

  The pressure P1 is a pressure upstream of the throttle valve 34 a of the throttle valve device 34 for low pressure EGR in the intake passage 31. The pressure upstream of the throttle valve 34a in the intake passage 31 is the same as the atmospheric pressure. For this reason, in the present embodiment, the pressure value of the atmospheric pressure is used as the pressure value upstream of the throttle valve 34a in the intake passage 31. The atmospheric pressure is detected by a pressure sensor 90 provided in the automobile 1. The pressure sensor 90 is connected to the engine ECU 60. The detection result of the pressure sensor 90 is transmitted to the engine ECU 60.

  In step ST31, the engine ECU 60 uses the detection result transmitted from the pressure sensor 90 as a pressure value upstream of the throttle valve 34a in the intake passage 31.

  Instead of the pressure sensor 90, a sensor that detects the amount of pressure upstream of the throttle valve 34a in the intake passage 31 may be used.

  When the temperature T1, the intake air amount G, and the pressure P1 are detected, the process proceeds to step ST32.

  In step ST32, the engine ECU 60 detects the density ρ1 of the air upstream of the throttle valve 34a in the intake passage 31. Specifically, engine ECU 60 detects density ρ1 based on temperature T1, intake air amount G, and pressure P1 obtained in step ST31.

The density ρ1 can be obtained by the following equation.

  R1 is a gas constant. The gas constant R1 is known. When the density ρ1 is obtained, the process proceeds to step ST33.

In step ST <b> 33, the engine ECU 60 obtains a limit negative pressure value P < _b > ₂ that acts on a portion between the low pressure EGR throttle valve device 34 and the first portion 51 of the turbocharger 50 in the intake passage 31. It explained limit negative pressure value _{P 2.}

When negative pressure acts on the portion of the intake passage 31 between the throttle valve 34a and the first portion 51, a load is applied to the first portion 51 as described above. Limit negative pressure value P ₂ is the pressure range in which the first portion 51 can withstand. In other words, if the negative pressure acting between the throttle valve 34 a and the first portion 51 in the intake passage 31 is less than or equal to the limit negative pressure value P ₂ , the first portion 51 is connected to the throttle valve 34 a in the intake passage 31. And the first portion 51 is not damaged due to the negative pressure acting between them. Here, the term “below the limit negative pressure value” is a concept including the limit negative pressure value. Limit negative pressure value P ₂ is, for example, can be obtained in advance by experiments or the like. Limit negative pressure value P ₂ is an example of a predetermined value in the present invention.

  When the negative pressure increases, the pressure in the portion of the intake passage 31 between the throttle valve 34a and the first portion 51 is smaller than the pressure in the portion of the intake passage 31 downstream of the first portion 51. It shows that the difference becomes large. When the negative pressure is reduced, the pressure in the portion of the intake passage 31 between the throttle valve 34a and the first portion 51 is smaller than the pressure in the portion of the intake passage 31 downstream of the first portion 51. It shows that the difference becomes small.

In the present embodiment, the limit negative pressure value P ₂ is stored has been determined in advance one value, for example, the engine ECU 60. Therefore, the engine ECU60 grasps the limit pressure value _{P 2.} Then, the process proceeds to step ST34.

In step ST34 or later, the engine ECU60 is negative pressure acting on the range between the throttle valve 34a and the first portion 51 in the intake passage 31, for not less than the limit negative pressure _{P 2,} the throttle pressure EGR The opening degree of the valve device 34 is obtained.

First, in order to obtain the opening degree, in step ST34, the engine ECU 60 detects τ _lmt (P ₁ / P ₂ ) using a nozzle equation. τ _lmt (P ₁ / P ₂ ) can be obtained by the following equation.

k is the specific heat ratio of air. τ _lmt (P ₁ / P ₂ ) may be calculated each time using the above (Equation 2), or for simplicity, assuming that k is a constant value, τ _lmt (P ₁ / P ₂ ) and (P ₁ / P ₂ ) may be obtained by mapping in advance and referring to the map. When τ _lmt (P ₁ / P ₂ ) is obtained, the process proceeds to step ST35.

Engine ECU60, in step ST35, the pressure of the portion between the throttle valve 34a and the first portion 51 is the limit negative pressure _{P 2} in the intake passage 31, is the opening area of the low pressure EGR throttle valve device 34 The limit opening area _Fthrmt is obtained.

  The opening area will be described. The opening area is an area of a gap formed between the inner surface 31c of the intake passage 31 and the throttle valve 34a when the throttle valve 34a is viewed along the direction in which the intake passage 31 extends. FIG. 5 is a cross-sectional view of the intake passage 31 shown along line F5-F5 shown in FIG. FIG. 5 shows a state in which the inside of the intake passage 31 is viewed along the arrow z. The direction indicated by the arrow z is the direction in which the intake passage 31 extends and the direction in which the air A flows.

In FIG. 5, the opening of the low pressure EGR throttle valve device 34 is a substantially intermediate opening between the minimum opening and the maximum opening. In FIG. 5, the gap formed between the inner surface 31 c of the intake passage 31 and the throttle valve 34 a as viewed along the arrow X is hatched with a two-dot chain line. The opening area is an area in a hatched range. The two-dot chain line hatching does not indicate a cross section. The opening area varies depending on the attitude of the throttle valve 34a. Further, the opening area increases as the opening degree increases. The limit opening area _Fthrmt is obtained by the following equation.

When _Fthrmt is obtained, the process proceeds to step ST36.

In step ST36, the engine ECU 60 detects a limit opening that is an opening of the low-pressure EGR throttle valve device 34, which corresponds to the limit opening area _Fthrmt . As described above, the engine ECU 60 includes information on the limit opening degree _θthrmt of the throttle valve device 34 for low pressure EGR corresponding to the limit opening area _Fthrmt . FIG. 6 is a map showing the limit opening area _Fthrmt of the low-pressure EGR throttle valve device 34 corresponding to the limit opening angle _θthrmt of the low-pressure EGR throttle valve device 34. The map shown in FIG. 6 is an example of the above information.

In FIG. 6, the horizontal axis indicates the limit opening θ _thrlmt . The horizontal axis indicates that the limit opening degree θ _thrmt increases as it proceeds along the arrow x. The vertical axis represents the limit opening area _Fthrmt . The vertical axis indicates that the limit opening area _Fthrmt increases as it proceeds along the arrow y.

As shown in FIG. 6, there is a one-to-one relationship between the limit opening degree _θthrmt and the limit opening area _Fthrmtt . When the limit opening theta _Thrlmt corresponding to the limit opening area _{F Thrlmt} is required, then, before proceeding to a step ST4.

3, the engine ECU60, in step ST4, compared with the restriction opening theta _Thrlmt determined at the optimal angle theta _suit the step ST3 obtained in step ST2, the optimum angle theta _suit restrictions opening It is determined whether it is _{equal to} or greater than _θthrmt . That the optimum opening theta _suit restrictions opening theta _Thrlmt above is a concept including optimal opening theta _suit = restriction opening _θ thrlmt.

If optimum opening theta _suit is restricted opening theta _Thrlmt above, the process proceeds to step ST5. In step ST5, the engine ECU 60 sets the optimum opening θ _suite as the target opening θ _target when controlling the opening of the low pressure EGR throttle valve device 34. The target opening referred to here is a target value for controlling the opening of the low-pressure EGR throttle valve device 34.

By optimal opening theta _suit is restricted opening theta _Thrlmt above, the pressure of the portion between the throttle valve 34a and the first portion 51 in the intake passage 31, becomes larger than the limit negative pressure _{P 2} There is no. Therefore, setting the optimal opening theta _suit the target opening theta _target, the negative pressure portion between the throttle valve 34a and the first portion 51 in the intake passage 31, the limit negative pressure value _{P 2} It will never grow. Then, the process proceeds to step ST7.

In step ST7, the engine ECU 60 controls the valve drive unit 34b of the low pressure EGR throttle valve device 34 to set the opening of the low pressure EGR throttle valve device 34 to the target opening θ _target . Note that, as described above, the engine ECU 60 has information on the rotation angle of the throttle valve 34a corresponding to the opening, so that the throttle valve 34a is based on the minimum opening based on this information. Adjust to the rotation angle position.

In step ST4, the optimum angle theta _suit is determined to be below the limit opening area _{F thrlmt,} it proceeds from step ST4 to step ST6. In step ST6, the engine ECU 60 sets the limit opening θ _throwlm as the target opening θ _target . If optimum opening theta _suit is lower than the limit angle theta _Thrlmt, when the optimum angle theta _suit the degree of opening of the low-pressure EGR throttle valve device 34, the throttle valve 34a and the first portion 51 in the intake passage 31 negative pressure acting on the portion between is larger than the limit negative pressure P _2.

If optimum opening theta _suit is lower than the limit angle _θ thrlmt, by a restriction opening theta _Thrlmt the target opening theta _target, acting between the throttle valve 34a and the first portion 51 in the intake passage 31 negative pressure does not become greater than the limit negative pressure P _2.

FIG. 7 is a graph showing the optimum opening degree θ _suite of the throttle valve device 34 for low pressure EGR when the automobile 1 is in a certain driving state. The horizontal axis in FIG. 7 indicates time. The horizontal axis indicates that time passes as it proceeds along the arrow p. The vertical axis _| shaft of FIG. 7 has shown the optimal opening degree (theta) _suit . The vertical axis indicates that the optimum opening degree θ _suite increases as it proceeds along the arrow q.

FIG. 8 shows the throttle valve 34a and the first portion in the intake passage 31 when the engine ECU 60 controls the valve drive unit 34b with the optimum opening θ _suite shown in FIG. The negative pressure value acting between the two and 51 is shown. The horizontal axis in FIG. 8 indicates the same time as in FIG. The vertical axis in FIG. 8 indicates the negative pressure value acting between the throttle valve 34 a and the first portion 51 in the intake passage 31. The vertical axis in FIG. 8 indicates that the negative pressure value increases as it proceeds along the arrow r.

As shown in FIG. 8, at time t1, t2, t3, is larger than the negative pressure limit negative pressure P ₂ acting between the throttle valve 34a and the first portion 51 in the intake passage 31 Yes.

FIG. 9 shows the limit opening θ _thrlmt in the driving state of the automobile 1 shown in FIG. The horizontal axis in FIG. 9 indicates the same time as in FIG. The vertical axis in FIG. 9 indicates the limit opening θ _thrlmt of the throttle valve device 34 for low pressure EGR. The vertical axis indicates that the limit opening degree θ _thrlmt increases as it proceeds along the arrow s.

Figure 10 shows the target opening theta _target of the restriction opening theta _Thrlmt obtained as a result of comparison in step ST4 illustrated in optimum opening theta _suit and 9 shown in FIG. The horizontal axis in FIG. 10 is the same as that in FIG. 7 and indicates time. The vertical axis represents the target opening θ _target . The vertical axis indicates that the target opening degree θ _target increases as it proceeds along the arrow u.

In the flowchart shown in FIG. 3, at the times t1, t2, and t3 shown in FIG. 10, in step ST4, the limit opening _θthrmt is adopted as the target opening θ _target .

FIG. 11 shows the throttle valve 34a in the intake passage 31 when the engine ECU 60 controls the valve drive unit 34b so that the opening degree of the low pressure EGR throttle valve device 34 becomes the target opening degree θ _target shown in FIG. A negative pressure value acting on a portion between the first portion 51 and the first portion 51 is shown. The horizontal axis in FIG. 11 indicates the same time as in FIG. The vertical axis in FIG. 11 indicates the negative pressure acting on the portion of the intake passage 31 between the throttle valve 34 a and the first portion 51. The vertical axis indicates that the negative pressure increases as it proceeds along the arrow v.

As shown in FIG. 11, since the limit opening θ _thrlmt is adopted as the target opening θ _target at times t1, t2 and t3, it acts on the portion between the throttle valve 34a and the first portion 51 in the intake passage 31. to the negative pressure does not become greater than the limit negative pressure P _2.

In step ST7, the engine ECU 60 returns to step ST1 when the valve drive unit 34b is controlled so that the opening degree of the throttle valve device 34 for low pressure EGR becomes the target opening degree θ _target . Until the driving of the diesel engine 20 is stopped, the engine ECU 60 repeats the operations of steps ST1 to ST7.

  When the driving of the diesel engine 20 is stopped, the operation of the engine ECU 60 is stopped.

  Further, when the engine ECU 60 guides the exhaust gas H to the combustion chambers 21 a to 21 d according to the operating state of the diesel engine 20, the engine ECU 60 opens the low-pressure EGR valve 73 and the high-pressure EGR valve 83 and sends the exhaust gas H to the intake passage 31. Lead.

In thus constructed internal combustion engine system 10, when the restriction opening theta _Thrlmt is optimal opening theta _suit above, the restriction opening theta _Thrlmt with the target opening theta _target. As a result, the negative pressure acting on the portion between the throttle valve 34a and the first portion 51 in the intake passage 31 becomes larger than the limit negative pressure value while maintaining the state in which the diesel engine 20 is optimally operated. There is no.

Also, easy in order to detect restriction opening theta _Thrlmt, the temperature T1 of the air passing through the throttle valve device 34 for low-pressure EGR, and intake air amount G, and using the detection pressure P1, the restriction opening theta _Thrlmt Can be detected.

Next, an internal combustion engine device according to a second embodiment of the present invention will be described with reference to FIG. In addition, the structure which has the same function as 1st Embodiment attaches | subjects the code | symbol same as 1st Embodiment, and abbreviate | omits description. In the present embodiment, only the method of calculating the limit negative pressure P ₂ is different from the first embodiment. Others are the same as the first embodiment. For this reason, since the structure of the internal combustion engine device is the same as that of the first embodiment, reference numeral 10 is given. The operation other than the operation for obtaining the limit negative pressure P ₂ of the internal combustion engine system 10 is the same as the first embodiment.

In the present embodiment, the limit negative pressure value P ₂ is not a single value is predetermined as in the first embodiment, is determined based on the operating state of the diesel engine 20. Engine ECU60 is previously provided with information limit negative pressure P ₂ which is determined according to the operating state of the diesel engine 20. This information is obtained by experiments, for example.

In the present embodiment, as an example of the operation state of the diesel engine 20, information on the diesel engine 20 and the rotation speed (rpm) and information on the engine load on which the diesel engine 20 acts are used. Engine ECU60 is a diesel engine 20 and the rotation speed and (rpm), stores in advance information indicating the limit negative pressure P ₂ which is determined in accordance with the load acting of the diesel engine 20. The rotation speed of the diesel engine 20, a limit negative pressure value P ₂ is determined in accordance with the load acting on the diesel engine 20 is obtained in advance by experiments.

FIG. 12 shows the effect on the portion between the throttle valve 34 a and the first portion 51 in the intake passage 31, which is determined according to the rotational speed (rpm) of the diesel engine 20 and the load acting on the diesel engine 20. is a map showing the limit negative pressure P ₂ to. This map is an example of the above information.

  The horizontal axis in FIG. 12 indicates the rotational speed of the diesel engine 20. The horizontal axis indicates that the number of rotations increases as the vehicle proceeds along the arrow a. The vertical axis in FIG. 12 indicates the engine load acting on the diesel engine 20. The vertical axis indicates that the engine load increases as it proceeds along the arrow b.

In this embodiment, the engine ECU 60 detects the engine load and the rotational speed by means not shown in step ST33 shown in FIG. 4, and based on the detection result and the map shown in FIG. determine the P _2.

In the present embodiment, it is possible to obtain the same operations and effects as in the first embodiment. Furthermore, the limit negative pressure value P ₂ can be set to a more appropriate value by obtaining the limit negative pressure value P ₂ according to the operating state of the diesel engine 20.

  In the first and second embodiments, a diesel engine is used as an example of an engine referred to in the present invention. However, the present invention is not limited to this. For example, a gasoline engine may be used.

  In the first and second embodiments, the low pressure EGR device 70 and the high pressure EGR device 80 are used. However, the low pressure EGR device 70 and the high pressure EGR device 80 may not be provided. As in the first and second embodiments, the present invention is similarly applied to an internal combustion engine apparatus that includes a valve that adjusts the amount of intake air supplied to the combustion chamber upstream of the supercharger in the intake passage 31. The following actions and effects can be obtained.

  In the first and second embodiments, the engine ECU 60 is an example of a limit opening degree calculation unit, an example of a target opening degree calculation unit, and an example of a valve driving unit.

  In the first and second embodiments, the turbocharger 50 is used as an example of the supercharger referred to in the present invention. However, it is not limited to this. For example, a supercharger may be used.

The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above. Furthermore, you may combine the component covering different embodiment suitably.
The contents described in the claims at the beginning of the application of the present application will be appended.
[1]
An internal combustion engine, an intake passage connected to the internal combustion engine, a supercharger provided in the intake passage, a throttle valve provided upstream of the supercharger in the intake passage, and the supercharge in the intake passage A limit opening calculating means for calculating a limit opening of the throttle valve at which a pressure acting on a portion between the throttle valve and the throttle valve becomes a predetermined value, and a restriction on the throttle valve calculated by the limit opening calculating means The opening degree is compared with the optimum opening degree of the throttle valve determined according to the state of the internal combustion engine, and if the optimum opening degree is not less than the limit opening degree, the target value of the opening degree of the throttle valve A target opening calculation means for setting the target opening as the limit opening when the optimum opening is less than the limit opening, and the target opening calculation means of Internal combustion engine system, characterized by comprising a valve drive means for opening and closing the throttle valve based on the output results.
[2]
The limit opening degree calculation means includes the predetermined value of the pressure acting on a portion between the supercharger and the throttle valve in the intake passage, the pressure upstream of the throttle valve in the intake passage, and the intake air 2. The internal combustion engine device according to 1, wherein the temperature of the air flowing upstream of the throttle valve in the passage and the intake air amount are detected, and the limit opening is obtained based on these values.
[3]
1 or 2, wherein the predetermined value of the pressure acting on a portion between the supercharger and the throttle valve is obtained based on a rotational speed of the internal combustion engine and a load of the internal combustion engine. The internal combustion engine device described.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine apparatus, 20 ... Diesel engine (internal combustion engine), 31 ... Intake passage, 34a ... Throttle valve, 50 ... Turbocharger (supercharger), 60 ... Engine ECU (limit opening calculation means, target opening calculation) Means, valve drive means).

Claims (2)

An internal combustion engine;
An intake passage connected to the internal combustion engine;
A supercharger provided in the intake passage;
A throttle valve provided upstream of the supercharger in the intake passage;
A pressure upstream of the throttle valve in the intake passage, a temperature of air flowing upstream of the throttle valve in the intake passage, and an intake air amount are detected, and the excess air in the intake passage is detected based on these values. Limit opening calculation means for calculating a limit opening of the throttle valve at which a pressure acting on a portion between the feeder and the throttle valve becomes a predetermined value;
The limit opening of the throttle valve calculated by the limit opening calculation means is compared with the optimum opening of the throttle valve determined according to the state of the internal combustion engine, and the optimum opening is determined by the limit opening. When it is above, the target opening that is the target value of the opening of the throttle valve is set as the optimum opening, and when the optimum opening is less than the limit opening, the target opening is set as the limit opening. Target opening degree calculation means for
Valve drive means for opening and closing the throttle valve based on the detection result of the target opening degree calculation means ,
The internal combustion engine apparatus is characterized in that the operations of the limit opening calculation means, the target opening calculation means, and the valve driving means are repeatedly executed while the internal combustion engine is being driven . Wherein the predetermined value of the pressure acting on the portion between the throttle valve and the supercharger, the rotation speed of the internal combustion engine, in claim 1, characterized in that it is determined based on the load of the internal combustion engine The internal combustion engine device described.

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