JP5245470B2 - Control device for an internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to control of an internal combustion engine with a supercharger, and more particularly to control of an internal combustion engine having both a mechanical supercharger and a turbocharger.

  As a supercharger for an internal combustion engine, a mechanical supercharger driven by an output shaft of the internal combustion engine and a turbocharger driven by exhaust energy of the internal combustion engine are known. Since the mechanical supercharger is driven by the output shaft of the internal combustion engine, supercharging can be performed effectively from the low engine speed range, but the engine output loss due to its driving resistance increases at the high engine speed range. There is. On the other hand, since the turbocharger is driven by exhaust energy, it cannot perform supercharging effectively in the low engine speed range where the exhaust flow rate is low, but has a characteristic that the engine output loss is small in the high engine speed range. .

A mechanical supercharger and a turbocharger having such characteristics, and a clutch for connecting / disconnecting the connection between the mechanical supercharger and the output of the internal combustion engine are provided, and the mechanical supercharger is based on the engine speed and the load. Patent Document 1 discloses a configuration in which it is determined whether the area for driving the machine is an area to be stopped, and the area to be driven is enlarged and corrected during acceleration.
JP-A-2-55832

  However, in the configuration disclosed in Patent Document 1, when correcting the drive region of the mechanical supercharger during acceleration, the correction amount is set based on the throttle opening, regardless of the supercharging pressure of the turbocharger. Has been decided. For this reason, for example, the turbocharging pressure of the turbocharger is sufficiently increased, and even when the mechanical supercharger is driven, supercharging by the mechanical supercharger is practically hardly performed. Even so, if the amount of change in the throttle opening is large, the clutch will be engaged, so the frequency of use of the mechanical supercharger increases, and the fuel consumption required to increase the torque when driving the mechanical supercharger There is a problem that the amount increases.

  Accordingly, an object of the present invention is to control the driving of the mechanical supercharger so as to suppress the deterioration of fuel consumption while satisfying the acceleration request.

A control apparatus for an internal combustion engine with a supercharger according to the present invention is a turbocharger that is driven by exhaust gas from the internal combustion engine, and is driven by an output shaft of the internal combustion engine that is located in an intake passage downstream of the turbocharger. An internal combustion engine with a supercharger comprising: a mechanical supercharger; and an electromagnetic clutch capable of switching between an engaged state in which the mechanical supercharger and an output shaft of the internal combustion engine are connected to each other and a released state in which both are disconnected In the engine control apparatus, turbocharger supercharging pressure detecting means for detecting a supercharging pressure downstream of the turbocharger and upstream of the mechanical supercharger, engine speed detecting means for detecting the engine speed, and acceleration Acceleration request detection means for detecting presence / absence of request and magnitude of request acceleration, request torque calculation means for calculating request torque at the time of request for acceleration, and fastening in which the request torque is set for each engine speed at the time of request for acceleration -Exceeds the threshold for release determination It has an electromagnetic clutch control means for fastening the electromagnetic clutch when that, the, the electromagnetic clutch control means, the turbocharger downstream of calculating, based on the size and engine speed required acceleration during acceleration request The target pressure increase speed is compared with the actual pressure increase speed calculated based on the detection value of the turbocharger supercharging pressure detection means, and the electromagnetic clutch is engaged when the actual pressure increase speed is smaller. .

  According to the present invention, since the determination criterion of the engagement / release of the electromagnetic clutch is changed according to the measured supercharging pressure of the turbocharger, it is possible to perform the engagement / release control according to the operation state, which is unnecessary. In addition, the driving of the mechanical supercharger can be prevented and deterioration of fuel consumption can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of an internal combustion engine with a supercharger to which the present embodiment is applied. 1 is an internal combustion engine, 2 is an intake manifold, 3 is an exhaust manifold, 4 is an intake passage, 5 is a bypass passage, 6 is a bypass valve, and 7 is an electronically controlled throttle valve (hereinafter simply referred to as “throttle valve”). 8) is a mechanical supercharger, 11 and 12 are pressure sensors, 13 is a crank angle sensor as engine speed detection means, 14 is a rotation sensor that detects the rotational speed of the mechanical supercharger, and 15 is A turbocharger, 16 is an exhaust passage, 17 is a controller as required torque calculation means and clutch control means, and 18 is an accelerator opening sensor as acceleration request detecting means for detecting the opening of an accelerator pedal (not shown). The pressure sensor 11 is a pressure between the mechanical supercharger 8 and the throttle valve 7, and the pressure sensor 12 is a turbocharger supercharging pressure detecting means between the turbocharger 15 and the mechanical supercharger 8. The pressure of each is detected.

  A throttle valve 7 that variably adjusts the cross-sectional area of the flow path is provided near the inlet of the intake manifold 2 in the intake passage 4, and a mechanical supercharger 8 is interposed upstream of the throttle valve 7. The bypass passage 5 communicates the upstream side of the throttle valve 7 and the downstream side of the mechanical supercharger 8 with the downstream side of the mechanical supercharger 8 and variably adjusts the cross-sectional area of the flow path in the passage. A bypass valve 6 is provided.

  The mechanical supercharger 8 includes a compressor rotation shaft 8a, a pulley 8b provided at the tip of the rotation shaft 8a, and an electromagnetic clutch 9 that connects and disconnects rotation transmission from the pulley 8b to the rotation shaft 8a. A belt or chain 10 is wound around the pulley 8b and the crank pulley 1b provided at the tip of the crankshaft 1a of the internal combustion engine 1. When the crankshaft 1a rotates, the pulley 8b also rotates synchronously. When the electromagnetic clutch 9 is engaged, the rotating shaft 8a rotates and is supercharged by the mechanical supercharger 8. When the electromagnetic clutch 9 is released, the rotating shaft 8a does not rotate. Not done. The switching of the engagement / release of the electromagnetic clutch 9, the opening control of the throttle valve 7, and the opening control of the bypass valve 6 are based on detection signals of the crank angle sensor 13, the rotational speed sensor 14, the pressure sensors 11, 12, and the like. , Performed by the controller 17. Details will be described later.

  The turbocharger 15 includes a compressor 15a and a turbine 15b connected via a shaft 15c, and the compressor 15a is upstream of the mechanical supercharger 8 and upstream of the junction between the bypass passage 5 and the intake passage 4. The turbines 15 b are respectively disposed in the exhaust passages 16 on the downstream side of the exhaust manifold 3. When the turbine 15b is rotated by the exhaust gas, the compressor 15a connected via the shaft 15c is also rotated, and the intake air flowing through the intake passage 4 is pumped.

  The controller 17 reads detection signals from the pressure sensors 11 and 12, the crank angle sensor 13, the rotation speed sensor 14, the accelerator opening sensor 18, and the like. Based on these detection signals, the bypass valve 6 and the throttle valve 7 are opened. Degree control, engagement / release control of the electromagnetic clutch 9 and the like.

  FIG. 2 is a diagram for explaining the basic concept of the engagement / release control of the electromagnetic clutch 9 during acceleration. The vertical axis is the engine torque, the horizontal axis is the engine speed, the solid line in the figure shows the torque characteristics of the above system using the mechanical supercharger 8 and the turbocharger 15 together, and the broken line is the turbocharger The torque characteristic in the case of only 15 is shown.

  When there is an acceleration request, if the operating point determined by the engine speed Ne and the torque is in the region of the rotational speed Nech or less, the electromagnetic clutch 9 is engaged, and the mechanical supercharger 8 and the turbocharger 15 are set. Supercharge by. Thereby, as shown by the broken line in the figure, the supercharging pressure can be increased by the mechanical supercharger 8 from the low rotation region where the supercharging pressure of the turbocharger 15 is low. In FIG. 2, the increase in the supercharging pressure of the turbocharger 15 is constant after the torque from the mechanical supercharger 8 and the turbocharger 15 increases and reaches the full load. This is because the opening degree of the bypass valve 6 is also expanded.

  If the rotation speed is higher than Nech, the electromagnetic clutch 9 is released and the turbocharger 15 alone performs supercharging. This is because the torque generated only by the turbocharger 15 is increased to the same level as the torque when the mechanical supercharger 8 and the turbocharger 15 are used together. 8 is a state in which supercharging by 8 is not performed (so-called idling state), and if the electromagnetic clutch 9 is left engaged, the fuel efficiency is deteriorated due to output loss caused by driving the mechanical supercharger 8. is there.

  However, a response delay occurs in the boost pressure increase of the turbocharger 15, and this response delay changes depending on the intake air flow rate, the rotational speed of the turbine 15b, the engine load, and the like. Therefore, in the present embodiment, the engagement / release of the electromagnetic clutch 9 is determined by the control described below.

  FIG. 3 is a flowchart of engagement timing control of the electromagnetic clutch 9 executed by the controller 17. This control is repeatedly executed when there is an acceleration request.

  In step S1, the engine speed Ne, the supercharging pressure Pt of the turbocharger 15, the supercharging pressure Psc of the mechanical supercharger 8, and the accelerator opening APO are read. The supercharging pressure Pt of the turbocharger 15 is a detected value of the pressure sensor 12, the supercharging pressure Psc of the mechanical supercharger 8 is a detected value of the pressure sensor 11, and the accelerator opening APO is the value of the accelerator opening sensor 18. Read the detected value.

  In step S2, it is determined whether or not the required torque is smaller than the threshold value 1 based on the map of FIG. In FIG. 4, the vertical axis represents torque, the horizontal axis represents engine speed, and the curve in the figure is a boundary line between the electromagnetic clutch 9 engagement region and the release region (that is, torque that can be achieved only by the turbocharger 15). A certain threshold value 1 is shown. The required torque is calculated from the engine speed Ne and the accelerator opening APO, and it is determined whether or not the required torque is smaller than the threshold value 1. If the required torque is smaller, the process proceeds to step S3, and if larger, the process proceeds to step S11.

  In step S3, it is determined based on the map of FIG. 5 whether the acceleration intention (that is, the amount of time change in the accelerator opening) ΔAPO is smaller than the threshold value 2. In FIG. 5, the vertical axis represents the acceleration intention ΔAPO, the horizontal axis represents the engine speed, and the solid line in the figure represents the threshold 2 that is a value determined by the response time of the turbocharger 15. When the acceleration intention ΔAPO is smaller, the process proceeds to step S4, and when larger, the process proceeds to step S11.

  In step S4, the fastening torque of the electromagnetic clutch 9 is changed based on the table of FIG. In FIG. 6, the vertical axis represents the clutch engagement torque Tcr, the horizontal axis represents the supercharging pressure Ptc of the turbocharger 15, and the higher the supercharging pressure Ptc, the larger the clutch engagement torque Tcr. This is because the electromagnetic clutch 9 is fastened at a higher rotational speed, and thus a larger fastening torque is required.

  In step S5, the target pressure increase rate ΔPest of the turbocharger 15 is calculated. Here, a map in which the target pressure increase rate ΔPest is assigned to the acceleration intention ΔAPO and the engine speed Ne is created in advance, and is calculated by searching this map.

  In step S6, the actual pressure increase speed ΔPreal of the turbocharger 15 is calculated. Here, the difference between the current supercharging pressure Ptc and the supercharging pressure Ptc at the previous calculation is calculated by dividing by the calculation interval time.

  In step S7, it is determined whether or not the actual pressure increase rate ΔPreal is equal to or higher than the target pressure increase rate ΔPest. As a result, when the actual pressure increase rate ΔPreal is equal to or higher than the target pressure increase rate ΔPest, the process proceeds to step S8, and when smaller than the target pressure increase rate ΔPest, the process proceeds to step S9.

  In step S8, the electromagnetic clutch 9 is kept released.

  In step S9, it is determined whether or not the throttle opening TVO is maximized. If not, the process proceeds to step S10, the throttle opening TVO is increased by a predetermined value, and the process returns to step S5. If it is maximum, the process proceeds to step S11.

  In step S11, the electromagnetic clutch 9 is engaged. The power supplied to the electromagnetic clutch 9 is set to a preset value when the process proceeds from step S2 or S3 to step S11, and the clutch engagement calculated at step S4 is performed when the process proceeds from step S9 to step S11. A value determined based on the torque Tcr is set.

  As described above, according to the target torque determined according to the acceleration request, the supercharger that uses both the mechanical supercharger 8 and the turbocharger 15 or the turbocharger 15 alone is selected. When the actual pressure increase rate ΔPreal of the supercharging pressure is smaller than the target pressure increase rate ΔPest, first, the opening degree of the throttle valve 7 is increased. And supercharging by the mechanical supercharger 8 is started. Thereby, the drive frequency of the mechanical supercharger 8 can be suppressed and deterioration of fuel consumption can be suppressed.

  FIG. 7 is a time chart when the above control is executed and step S4 and subsequent steps are executed as a result of the determination in steps S2 and S3. In the chart of the supercharging pressure Psc of the mechanical supercharger 8, the alternate long and short dash line indicates the target supercharging pressure when the electromagnetic clutch 9 is engaged, the broken line indicates the actual supercharging pressure, and the solid line indicates the actual supercharging pressure. Indicates. In the chart of the supercharging pressure Ptc of the turbocharger 15, the solid line indicates the target supercharging pressure and the broken line indicates the actual supercharging pressure.

  Between times t1 and t2, the accelerator opening APO increases, and the opening of the throttle valve 7 also increases accordingly.

  Therefore, when the first calculation is performed at time t2, as a result of the determinations of steps S2 and S3, step S4 and subsequent steps are executed as described above. Here, since the pressure increase rate is zero for both the target value and the actual measurement value, the electromagnetic clutch 9 is started to be supercharged only by the turbocharger 15 while being released.

  As a result of performing the second calculation at time t3, it is assumed that the actual pressure increase rate ΔPreal of the supercharging pressure is smaller than the target pressure increase rate ΔPest. In this case, as shown in FIG. 7, since the throttle opening TVO has not yet been fully opened, the throttle opening TVO is increased. As a result, the pressure increase rate ΔPreal of the turbocharger 15 increases.

  As a result of the third calculation at time t4, it is assumed that the actual pressure increase rate ΔPreal of the supercharging pressure is still smaller than the target pressure increase rate ΔPest. In this case, since the throttle opening TVO is already fully opened, the electromagnetic clutch 9 is engaged and supercharging by the mechanical supercharger 8 is started.

  As described above, when the response delay of the supercharging pressure is large, first, the throttle opening TVO is increased to increase the boosting speed of the supercharging pressure, and when the rising speed is still slow, the electromagnetic clutch 9 is engaged. The start of operation of the mechanical supercharger 8 can be delayed until time t4.

  As described above, in the present embodiment, the following effects can be obtained.

  (1) A turbocharger 15 that is driven by exhaust gas from the internal combustion engine 1 and a mechanical supercharger that is located in the intake passage 4 on the downstream side of the turbocharger 15 and is driven by the output shaft 1a of the internal combustion engine 1 8, an internal combustion engine with a supercharger comprising an electromagnetic clutch 9 capable of switching between an engaged state in which the mechanical supercharger 8 and the output shaft of the internal combustion engine 1 are connected and a released state in which both are disconnected. , A pressure sensor 12 for detecting a supercharging pressure downstream of the turbocharger 15 and upstream of the mechanical supercharger 8, a crank angle sensor 13 for detecting the engine speed, the presence / absence of an acceleration request, and a requested acceleration An accelerator opening sensor 18 that detects the magnitude of the engine, and a controller 17 that calculates a required torque when requesting acceleration and selects engagement / release of an electromagnetic clutch based on the engine speed and the required torque when requesting acceleration. And Roller 17, so changing the criteria for selecting the engagement and disengagement of the electromagnetic clutch 9 according to the detected value of the pressure sensor 12, it is possible to engagement and disengagement control of the electromagnetic clutch 9 in accordance with the operating state.

  (2) The target pressure increase rate ΔPest and the actual pressure increase rate ΔPreal are compared when the acceleration is requested, and the electromagnetic clutch 9 is engaged when the actual pressure increase rate ΔPreal is smaller. The mechanical supercharger 8 is not driven, and deterioration of fuel consumption can be suppressed.

  (3) When the actual pressure increase rate ΔPreal is smaller than the target pressure increase rate ΔPest and the throttle opening TVO is not maximized, the throttle opening TVO is increased and the throttle opening TVO is maximized. Since the electromagnetic clutch 9 is engaged when the actual pressure increase rate ΔPreal is smaller than the target pressure increase rate ΔPest, the mechanical supercharger 8 is used only when the turbocharger 15 alone cannot satisfy the acceleration request. It will be driven. Thereby, power performance can be satisfied.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

1 is a system diagram of an internal combustion engine to which this embodiment is applied. It is a basic electromagnetic clutch engagement / release control map. It is a flowchart of fastening control of an electromagnetic clutch. It is a map showing the relationship between a request | requirement torque and a clutch fastening / release threshold value. It is a map showing the relationship between an accelerator opening change amount and a clutch fastening / release threshold value. It is a map showing the relationship between clutch fastening torque and supercharging pressure. It is a time chart at the time of performing control of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake manifold 3 Exhaust manifold 4 Intake passage 5 Bypass passage 6 Bypass valve 7 Throttle valve 8 Mechanical supercharger 9 Electromagnetic clutch 10 Belt 11 Pressure sensor 12 Pressure sensor 13 Crank angle sensor 14 Rotation sensor 15 Turbocharger 17 Controller

Claims (2)

A turbocharger driven by the exhaust of the internal combustion engine;
A mechanical supercharger located in an intake passage downstream of the turbocharger and driven by an output shaft of an internal combustion engine;
An electromagnetic clutch capable of switching between an engaged state in which the mechanical supercharger and the output shaft of the internal combustion engine are connected and a released state in which both are disconnected;
In a control device for an internal combustion engine with a supercharger comprising:
Turbocharger supercharging pressure detection means for detecting a supercharging pressure downstream of the turbocharger and upstream of the mechanical supercharger;
An engine speed detecting means for detecting the engine speed;
An acceleration request detecting means for detecting presence / absence of an acceleration request and a magnitude of the requested acceleration;
A required torque calculating means for calculating a required torque at the time of an acceleration request;
An electromagnetic clutch control means for engaging the electromagnetic clutch when the required torque exceeds a threshold for engagement / release determination set for each engine speed at the time of acceleration request;
Have
The electromagnetic clutch control means detects the target pressure increase speed on the downstream side of the turbocharger, which is calculated based on the magnitude of the requested acceleration and the engine speed when acceleration is requested , and the turbocharger supercharging pressure detection means A control device for an internal combustion engine with a supercharger , wherein the electromagnetic clutch is engaged when the actual pressure increase rate is smaller than the actual pressure increase rate calculated based on the value . An intake air amount adjusting means located downstream of the mechanical supercharger,
The electromagnetic clutch control means increases the opening amount of the intake air amount adjusting means when the actual pressure increasing speed is smaller than the target pressure increasing speed and the opening amount of the intake air amount adjusting means is not maximized. 2. The internal combustion engine with a supercharger according to claim 1 , wherein the electromagnetic clutch is engaged when the actual pressure increase rate is smaller than the target pressure increase rate even when the opening degree becomes maximum. Engine control device.

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