Control device for internal combustion engines
The control device addresses combustion failure and idleness in internal combustion engines by controlling throttle and EGR valve closure and using an intake mechanism to manage gas inflow, ensuring effective torque reduction during deceleration.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SUZUKI MOTOR CORP
- Filing Date
- 2024-12-23
- Publication Date
- 2026-07-03
Smart Images
Figure 2026111008000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a control device for an internal combustion engine.
Background Art
[0002] Conventionally, an exhaust gas recirculation (EGR) device has been known that can suppress the generation of nitrogen oxides and improve fuel efficiency by recirculating a part of the exhaust gas to the intake passage and burning it in the combustion chamber. In the exhaust gas recirculation device, an EGR valve for adjusting the recirculation amount of EGR gas is provided in the EGR passage. In a vehicle equipped with such an exhaust gas recirculation device, when there is a deceleration request by the driver, the opening degree of the EGR valve is controlled to decrease along with the opening degree of the throttle valve. However, due to the difference in the structure between the throttle valve and the EGR valve, the opening and closing speed of the EGR valve is slower than that of the throttle valve, so there is a problem that combustion failure occurs due to a temporary increase in the ratio of EGR gas to intake air.
[0003] In response to such a problem, in the control device for an internal combustion engine of Patent Document 1, it is disclosed that when there is a deceleration request by the driver, even if the closing of the EGR valve is delayed, the opening degree of the throttle valve is controlled to be further enlarged. Thus, by further enlarging the opening degree of the throttle valve, a large amount of air can flow into the cylinder, so that the destabilization of the combustion of the air-fuel mixture can be appropriately suppressed.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, if a large amount of air is introduced into the cylinder by increasing the throttle valve opening, as in the control device for an internal combustion engine described in Patent Document 1, it may not be possible to sufficiently reduce torque in response to the driver's request for deceleration, potentially resulting in a feeling of coasting. This invention has been made in view of the above-mentioned problems, and aims to suppress combustion failure while preventing the feeling of idleness. [Means for solving the problem]
[0006] The present invention relates to a control device for an internal combustion engine, comprising: an EGR passage for recirculating a portion of exhaust gas to an intake passage; an EGR valve for adjusting the flow rate of EGR gas flowing through the EGR passage; a throttle valve provided in the intake passage for adjusting the amount of intake air flowing into the combustion chamber; and an intake mechanism provided in the intake passage for drawing in the gas flowing through the intake passage, characterized in that it has a control unit that closes the throttle valve and the EGR valve when the vehicle is requested to decelerate, and controls the intake mechanism to draw in a portion of the gas, including the EGR gas, flowing through the intake passage. [Effects of the Invention]
[0007] According to the present invention, it is possible to suppress combustion failure while preventing the feeling of idleness. [Brief explanation of the drawing]
[0008] [Figure 1] This is a diagram showing the general configuration of the vehicle. [Figure 2] This flowchart shows an example of processing by a control device. [Figure 3] This figure shows various timing charts for processing performed by the control device. [Modes for carrying out the invention]
[0009] The internal combustion engine 10 of the embodiment of the present invention includes an EGR passage 151 that recirculates a portion of the exhaust gas to an intake passage 121, an EGR valve 152 that adjusts the flow rate of EGR gas flowing through the EGR passage 151, a throttle valve 124 provided in the intake passage 121 that adjusts the amount of intake air flowing into the combustion chamber 112, and an intake mechanism 16 provided in the intake passage 121 that inhales the gas flowing through the intake passage 121. The ECU 20 has a control unit 21 that closes the throttle valve 124 and the EGR valve 152 when the vehicle requests deceleration, and controls the intake mechanism 16 to inhale a portion of the gas, including the EGR gas flowing through the intake passage 121. By allowing the intake mechanism 16 to inhale a portion of the gas, including the EGR gas flowing through the intake passage 121, the control unit 21 can suppress the inflow of a large amount of gas into the combustion chamber 112, thereby suppressing combustion failure and preventing the feeling of idle. [Examples]
[0010] The control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. Figure 1 shows a schematic configuration of a vehicle 1 equipped with an internal combustion engine control device.
[0011] Vehicle 1 comprises an internal combustion engine 10, an ECU (Electronic Control Unit) 20 that controls the internal combustion engine 10, and a sensor unit 30. Vehicle 1 also includes other devices that are typically found in vehicles, and their illustration and description are omitted.
[0012] The internal combustion engine 10 includes an engine 11 as a power source, an intake system 12 for taking in air for combustion of the engine 11, an exhaust system 13 for discharging exhaust gas from the engine 11 to the outside, a fuel system 14 for supplying fuel to the engine 11, and an exhaust gas recirculation device (EGR device) 15, etc.
[0013] The engine 11 performs a series of four strokes: an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke. The engine 11 has a combustion chamber 112 in which a piston 111 is reciprocally housed, a crank chamber 113 in which a crankshaft 116 is rotatably housed, an intake port 114 which is the inlet for combustion air, and an exhaust port 115 which is the outlet for exhaust gas. The engine 11 also has a spark plug 117 positioned so that its tip is located inside the combustion chamber 112, an intake valve 118 located between the combustion chamber 112 and the intake port 114, and an exhaust valve 119 located between the combustion chamber 112 and the exhaust port 115. The configuration of the engine 11 is not particularly limited, and various known engines can be applied.
[0014] The intake system 12 includes an intake passage 121, an air cleaner 123, a throttle valve 124, and a surge tank 125. The intake passage 121 is a passage that guides intake air taken in from outside the vehicle 1 to the combustion chamber 112 via the intake port 114. The intake passage 121 is mainly composed of an intake pipe 122. The air cleaner 123 is located in the intake passage 121 and purifies the intake air by removing foreign matter such as dust and dirt contained in the intake air. The throttle valve 124 is located in the intake passage 121 and adjusts the intake air volume by opening and closing it. The valve body of the throttle valve 124 is a butterfly valve driven by a motor. The throttle valve 124 adjusts the intake air volume based on control by the ECU 20. The surge tank 125 temporarily stores the intake air, then rectifies it and guides it to the combustion chamber 112. The surge tank 125 functions as part of the intake passage 121.
[0015] The exhaust system 13 includes an exhaust passage 131 and a catalyst (catalytic converter) 133. The exhaust passage 131 is a passage that exhausts the exhaust gas burned in the combustion chamber 112 to the outside of the vehicle 1 via the exhaust port 115. The exhaust passage 131 is mainly composed of an exhaust pipe 132. The catalyst 133 purifies harmful substances contained in the exhaust gas. For example, various known three-way catalysts can be applied to the catalyst 133.
[0016] The fuel system 14 supplies fuel to the engine 11. The fuel system 14 includes a fuel tank, a fuel pump, and an injector 141. The fuel pump supplies fuel stored in the fuel tank to the injector 141. The injector 141 injects the fuel supplied from the fuel tank into the intake passage 121. The injector 141 adjusts the amount of fuel injected based on control by the ECU 20. Furthermore, the injector 141 is not limited to injecting fuel into the intake passage 121, but may also be configured to inject fuel into the combustion chamber 112.
[0017] The exhaust gas recirculation device 15 recirculates a portion of the exhaust gas burned in the combustion chamber 112 as EGR gas to the intake passage 121 for re-combustion in the combustion chamber 112. The exhaust gas recirculation device 15 includes an EGR passage 151 and an EGR valve 152. The EGR passage 151 connects the intake passage 121 and the exhaust passage 131, allowing a portion of the exhaust gas to be recirculated into the intake passage 121. Here, the exhaust gas flowing through the EGR passage 151 is the EGR gas. One end of the EGR passage 151 is connected to the exhaust pipe 132 downstream of the catalyst 133, and the other end is connected to the intake pipe 122 downstream of the throttle valve 124, more specifically, between the throttle valve 124 and the surge tank 125.
[0018] The EGR valve 152 is located in the EGR passage 151 and adjusts the amount of EGR gas (recirculation rate) that flows from the exhaust passage 131 to the intake passage 121 by opening and closing. The valve body of the EGR valve 152 is a poppet valve driven by a motor. Due to hardware limitations, the opening and closing speed of the EGR valve 152 is slower than the opening and closing speed of the throttle valve 124. The EGR valve 152 adjusts the amount of EGR gas based on control by the ECU 20. The exhaust gas recirculation device 15 may also include an EGR cooler in the EGR passage 151 to cool the EGR gas.
[0019] The intake mechanism 16 sucks in a part of the gas flowing through the intake passage 121. The intake mechanism 16 is connected to the downstream side of the throttle valve 124 in the intake passage 121 and further to the downstream side of the outlet of the EGR passage 151. The intake mechanism 16 has a negative pressure bag 161 and an adjustment valve 162. The negative pressure bag 161 has its interior maintained at a negative pressure and communicates with the intake passage 121 via the adjustment valve 162. The interior of the negative pressure bag 161 may be made negative pressure by a vacuum pump driven in conjunction with the engine 11 or a vacuum pump driven by a battery, etc., or the interior may be made negative pressure using the intake negative pressure of the intake passage 121. The adjustment valve 162 adjusts the flow rate of the gas sucked from the intake passage 121 into the negative pressure bag 161. The adjustment valve 162 is disposed between the intake passage 121 and the negative pressure bag 161. The adjustment valve 162 adjusts the flow rate of the gas to be sucked based on the control by the ECU 20.
[0020] The ECU 20 controls the entire vehicle 1. The ECU 20 corresponds to a control device for an internal combustion engine. As a hardware configuration, the ECU 20 has a CPU, a ROM, a RAM, etc. Programs and predetermined information for controlling the vehicle 1 and the internal combustion engine 10, etc. are stored in advance in the ROM. The RAM is a work memory and temporarily stores programs and data. The CPU reads out the programs stored in the ROM, expands them in the RAM, and executes them to control the vehicle 1 and the internal combustion engine 10, etc.
[0021] As a software configuration, the ECU 20 has a control unit 21, an estimation unit 22, etc. The control unit 21 controls the engine 11, the intake system 12, the exhaust system 13, the exhaust gas recirculation device 15, etc. The estimation unit 22 estimates the EGR rate. The processing by the control unit 21 and the estimation unit 22 will be described later with reference to the flowchart of FIG. 2.
[0022] The sensor unit 30 detects the driving situation, etc. in the vehicle 1 and transmits the detected results to the ECU 20. The sensor unit 30 has an accelerator opening sensor 31, a crank angle sensor 32, an intake pressure sensor 33, etc. The accelerator pedal position sensor 31 detects the amount of accelerator pedal operation performed by the driver of vehicle 1. The information of the operation amount detected by the accelerator pedal position sensor 31 is transmitted to the ECU 20. The crank angle sensor 32 detects the angle of the crankshaft 116. The angle information detected by the crankshaft 116 is transmitted to the ECU 20. The intake pressure sensor 33 detects the intake pressure of the gas flowing through the intake passage 121. In this case, the intake pressure sensor 33 is located inside the surge tank 125, but it is not limited to this case; it can be located anywhere in the intake passage 121 between the outlet of the EGR passage 151 and the intake mechanism 16. The intake pressure information detected by the intake pressure sensor 33 is transmitted to the ECU 20. Furthermore, the sensor unit 30 is not limited to the configuration described above, and may include various sensors that detect information necessary for the ECU 20 to control the vehicle 1 and the internal combustion engine 10, etc.
[0023] In this embodiment, in the internal combustion engine 10 configured as described above, the ECU 20 closes the throttle valve 124 and the EGR valve 152 when the vehicle 1 requests deceleration while the EGR gas is being recirculated to the intake passage 121 by the exhaust gas recirculation device 15. At this time, the ECU 20 performs a process to suppress combustion failure caused by a higher EGR rate due to the EGR valve 152 closing slower than the throttle valve 124, and also performs a process to suppress the feeling of coasting that occurs as a result of the combustion failure suppression process.
[0024] The operation of the ECU20 will be explained below with reference to the flowchart in Figure 2. The flowchart in Figure 2 is executed repeatedly at regular intervals after the engine 11 is started. The flowchart in Figure 2 is realized when the CPU of the ECU20 reads the program stored in ROM, loads it into RAM, and executes it. Here, it is assumed that the vehicle 1 is moving because the engine 11 is running.
[0025] In S10, the control unit 21 determines whether or not EGR gas is being recirculated into the intake passage 121. Specifically, the control unit 21 can determine that EGR gas is being recirculated into the intake passage 121 if the EGR valve 152 is open. If EGR gas is being recirculated, the process proceeds to S11; otherwise, the process shown in the flowchart in Figure 2 is terminated.
[0026] In S11, the estimation unit 22 estimates the EGR rate. The ECU 20 stores map data that defines the relationship between parameters (engine speed, accelerator opening) indicating the operating range of the internal combustion engine 10 when EGR gas is not recirculating (when the EGR valve 152 is closed) and the intake pressure value supplied to the combustion chamber 112 in each operating range. This map data is obtained experimentally or through simulation. The estimation unit 22 obtains the current engine speed and current accelerator opening from the crank angle sensor 32 and the accelerator opening sensor 31, and extracts the intake pressure value when the EGR valve 152 is closed from the map data. The extracted intake pressure value corresponds to the partial pressure of air in the gas flowing into the combustion chamber 112. The difference between the measured intake pressure and the intake pressure extracted from the map data corresponds to the partial pressure of EGR gas in the gas flowing into the combustion chamber 112. The measured value of the intake pressure can be obtained from the intake pressure sensor 33. Therefore, the estimation unit 22 can estimate the EGR rate (= partial pressure of EGR gas / measured intake pressure) based on the measured intake pressure and the intake pressure extracted from the map data.
[0027] In S12, the control unit 21 determines whether a deceleration request has been made based on the information from the accelerator pedal position sensor 31. The driver requests deceleration from the vehicle 1 by releasing or loosening the accelerator pedal. If a deceleration request has been made, the process proceeds to S13; otherwise, the process shown in the flowchart in Figure 2 ends.
[0028] In S13, the control unit 21 decelerates the vehicle 1 by closing the throttle valve 124 and the EGR valve 152 in response to the deceleration request, and by suppressing the injection amount from the injector 141. Here, since the closing speed of the EGR valve 152 is slower than the closing speed of the throttle valve 124, the EGR rate would increase if nothing were done. In this embodiment, the control unit 21 slows down the closing speed of the throttle valve 124 in order to suppress an increase in the EGR rate. At this time, the control unit 21 adjusts the closing speed of the throttle valve 124 based on the estimated EGR rate. Specifically, when the estimated EGR rate is high, the control unit 21 slows down the closing speed compared to when the estimated EGR rate is low, and when the estimated EGR rate is low, it speeds up the closing speed compared to when the estimated EGR rate is high. In this way, by intentionally slowing down the closing speed of the throttle valve 124, the EGR rate does not increase, and thus combustion failure can be suppressed.
[0029] In S14, the control unit 21 drives the intake mechanism 16. Specifically, the control unit 21 opens the adjustment valve 162 of the intake mechanism 16, thereby drawing a portion of the gas (including EGR gas) flowing through the surge tank 125 into the negative pressure bag 161. In S13, the closing speed of the throttle valve 124 is intentionally slowed down, so if nothing is done, a large amount of gas will flow into the combustion chamber 112, preventing a sufficient reduction in engine torque and causing a feeling of idleness. In this embodiment, the control unit 21 drives the intake mechanism 16 to prevent a portion of the gas (including EGR gas) from flowing into the combustion chamber 112, thereby reducing engine torque and suppressing the feeling of idleness. Since the intake mechanism 16 is located downstream of the outlet of the EGR passage 151, the gas drawn in by the intake mechanism 16 includes not only air but also EGR gas. In this way, because the intake mechanism 16 also inhales EGR gas, the EGR rate of the gas flowing into the combustion chamber 112 remains unchanged before and after inhalation by the intake mechanism 16, and the EGR rate does not increase, thus maintaining the suppression of combustion failure. Furthermore, the control unit 21 can reduce the engine torque to a level corresponding to the driver's accelerator operation by adjusting the opening of the adjustment valve 162 according to the accelerator opening detected by the accelerator opening sensor 31.
[0030] After the process in S14 is completed, the system returns to S10 and repeats the process described above. Furthermore, when no deceleration request has been made and the EGR gas is not being recirculated to the intake passage 121, the control unit 21 releases the negative pressure in the negative pressure bag 161 and opens the adjustment valve 162, thereby allowing the gas containing the EGR gas drawn into the negative pressure bag 161 to flow into the combustion chamber 112. At this time, the control unit 21 stores the EGR rate of the gas containing the EGR gas when it was drawn into the negative pressure bag 161, and estimates the amount of gas to flow into the combustion chamber 112 based on the stored EGR rate and the intake pressure detected by the intake pressure sensor 33, thereby injecting the required amount from the injector 141.
[0031] Figure 3 shows various timing charts. Figure 3(a) shows the accelerator pedal position. Figure 3(b) shows the throttle valve position. Figure 3(c) shows the amount of gas flowing into the combustion chamber. Figure 3(d) shows the EGR valve position. Figure 3(e) shows the engine speed. Furthermore, in Figures 3(c) and 3(e), the dashed lines show the timing chart when the control remains normal (comparative example), while the solid lines show the timing chart when the S14 process described above is executed (example).
[0032] Figure 3 shows the state in which EGR gas is recirculating into the intake passage 121 from time T0. As shown in Figure 3(a), a deceleration request is determined at time T1, and the accelerator opening decreases from time T1 to time T2. In Figures 3(b) and 3(d), the throttle valve opening and EGR valve opening decrease from time T1. However, as described above, the closing speed of the throttle valve 124 is controlled to be slower in S13, so as shown in Figure 3(b), the throttle valve opening gradually decreases from time T1 to time T3.
[0033] In Figure 3(c), as shown by the dashed line in the comparative example, under normal control, the amount of gas flowing into the combustion chamber 112 decreases in proportion to the throttle valve opening from time T1 to time T3. On the other hand, in this embodiment, since the intake mechanism 16 is driven in S14 as described above, the amount of gas flowing into the combustion chamber 112 decreases independently of the throttle valve opening, as shown by the solid line in Figure 3(c).
[0034] In Figure 3(e), as shown by the dashed line in the comparative example, under normal control, the engine speed gradually decreases from time T1 to time T3. However, in this embodiment, by reducing the amount of gas flowing into the combustion chamber 112, the engine speed can be reduced immediately in accordance with the throttle opening, as shown by the solid line in Figure 3(e), thus suppressing the feeling of coasting.
[0035] As described above, the ECU 20 of the internal combustion engine in this embodiment has a control unit 21 that closes the throttle valve 124 and the EGR valve 152 when the vehicle requests deceleration, and controls a portion of the gas, including the EGR gas flowing through the intake passage, to be drawn in by the intake mechanism 16. In this way, the control unit 21 can suppress the inflow of a large amount of gas into the combustion chamber 112 by causing a portion of the gas, including the EGR gas flowing through the intake passage 121, to be drawn in by the intake mechanism 16, thereby suppressing combustion failure and preventing the feeling of idleness.
[0036] In this embodiment, the intake mechanism 16 includes a negative pressure bag 161 whose interior is kept under negative pressure, and an adjustment valve 162 that adjusts the flow rate of gas from the intake passage 121 to the negative pressure bag 161. The control unit 21 controls the intake mechanism 161 to draw a portion of the gas, including the EGR gas, flowing through the intake passage 121 into the negative pressure bag 161 by opening the adjustment valve 162 when the vehicle is requested to decelerate. In this way, by using the negative pressure bag 161 and the adjustment valve 162, the intake mechanism 16 can be configured so that a portion of the gas, including the EGR gas, flowing through the intake passage 121 does not flow into the combustion chamber 112.
[0037] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and modifications can be made within the scope of the present invention. [Explanation of Symbols]
[0038] 1: Vehicle 10: Internal combustion engine 11: Engine 15: Exhaust gas recirculation device (EGR device) 151: EGR passage 152: EGR valve 16: Intake mechanism 161: Vacuum bag 162: Adjustment valve 20: ECU (Control Unit) 21: Control unit 22: Estimation unit 112: Combustion chamber 121: Intake passage 124: Throttle valve 131: Exhaust passage
Claims
1. An EGR passage that recirculates a portion of the exhaust gas into the intake passage, An EGR valve that adjusts the flow rate of EGR gas flowing through the aforementioned EGR passage, A throttle valve is provided in the intake passage and adjusts the amount of intake air flowing into the combustion chamber, A control device for an internal combustion engine, comprising: an intake mechanism provided in the intake passage for drawing in gas flowing through the intake passage, A control device for an internal combustion engine, characterized by having a control unit that closes the throttle valve and the EGR valve when the vehicle is requested to decelerate, and controls a portion of the gas, including the EGR gas, flowing through the intake passage to be drawn in by the intake mechanism.
2. The intake mechanism includes a negative pressure bag whose interior is kept under negative pressure, and an adjustment valve that adjusts the flow rate of gas flowing from the intake passage to the negative pressure bag. The control unit, The control device for an internal combustion engine according to claim 1, characterized in that when the vehicle is requested to decelerate, the adjustment valve is opened to control a portion of the gas, including the EGR gas flowing through the intake passage, to be drawn into the negative pressure bag.