JP4037342B2 - Device for controlling the output of an internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to an apparatus for controlling the output of an internal combustion engine with a supercharger.

  There is known a method of controlling the amount of intake air to an internal combustion engine (hereinafter referred to as an engine) by the opening of a throttle valve. It is also known to control the intake air amount by providing a supercharger and supplying pressurized air to the engine.

Patent Document 1 below describes a method of controlling the intake air amount by combining throttle control and supercharging pressure control. According to this technique, the throttle valve opening is continuously increased from zero to full open until the accelerator pedal opening reaches a predetermined value, and supercharging is not performed. After the accelerator pedal opening exceeds the predetermined value, the throttle valve is kept fully open and the boost pressure is continuously increased.
JP 7-150990 A

  As a supercharger, a turbocharger that performs supercharging with the energy of exhaust gas is known. The engine speed at which the supercharging pressure generated by the supercharger is maximized is generally called the intercept speed.

  When the engine speed is lower than the intercept speed, the engine output that can be generated by the supercharger is lower than when the engine speed is higher than the intercept speed. In the above conventional method, the throttle characteristic is determined without considering the intercept rotation speed. Therefore, when the engine speed is lower than the intercept rotation speed when the control is shifted from the throttle control to the supercharging pressure control, the engine output is smooth. There is a risk that it will not rise. Further, if the engine speed is higher than the intercept speed when the throttle control is shifted to the supercharging pressure control, the engine output may increase rapidly. Such a non-smooth change in engine output may cause discomfort to the driver.

  On the other hand, when the opening degree of the throttle valve reaches a predetermined value, a phenomenon in which the intake air amount is saturated occurs. This predetermined value is called a saturated throttle opening for convenience. Even if the opening of the throttle valve exceeds the saturation throttle opening, the engine output hardly increases. The saturation throttle opening varies depending on the engine speed.

  In the conventional method described above, when the intake air amount is saturated, the throttle control is switched to the supercharging pressure control, and when the supercharging pressure control is started, the engine output may rapidly increase. Such fluctuations in engine output can cause discomfort to the driver.

  Therefore, there is a need for a device that controls the engine output so that the engine output can smoothly change with respect to fluctuations in the accelerator pedal opening from throttle control to supercharging pressure control.

  According to one aspect of the present invention, an apparatus for controlling the output of an internal combustion engine equipped with a supercharger detects a rotational speed of the internal combustion engine and a throttle valve for adjusting the amount of air taken into the internal combustion engine. A rotation speed detecting means and an accelerator pedal opening degree detecting means for detecting the opening degree of the accelerator pedal are provided. When the detected accelerator pedal opening is equal to or less than a predetermined value, the control device includes a throttle control means for controlling the opening of the throttle valve based on the detected accelerator pedal opening, and the detected accelerator pedal opening If is larger than a predetermined value, a supercharging pressure control means for controlling the supercharging pressure generated by the supercharger is provided based on the detected accelerator pedal opening. The throttle control means controls the throttle valve so that the throttle valve opening relative to a given accelerator pedal opening is lower than the reference opening if the detected rotation speed is lower than the turbocharger intercept rotation speed. To do. The reference opening is the opening of the throttle valve with respect to the given accelerator pedal opening when the rotational speed of the internal combustion engine is the intercept rotational speed of the supercharger.

  When the engine speed is lower than the intercept speed, the engine output generated by the supercharger is lower than when the engine speed is higher than the intercept speed. According to the present invention, when the engine speed is lower than the intercept speed, the throttle valve is controlled so that the throttle characteristic changes more gently. Therefore, when the throttle control is switched to the supercharging pressure control, the engine output is reduced. It is possible to make a smooth transition.

  According to one embodiment of the present invention, if the detected engine speed is lower than the intercept rotational speed, the throttle control means of the control device may control the throttle valve with respect to the accelerator pedal opening as the detected engine rotational speed decreases. The throttle valve is controlled so that the change in the opening of the valve becomes gentle.

  The saturation throttle opening changes according to the engine speed. According to the present invention, the throttle valve is controlled so that the throttle opening gradually reaches the saturated throttle opening as the engine speed decreases. By such control, an increase in the dead zone in which the engine output does not react to fluctuations in the accelerator pedal opening is suppressed. Since an increase in the dead zone is suppressed, discomfort given to the driver is suppressed. Further, since the increase of the dead zone is suppressed, the engine output can be smoothly changed when the throttle control is switched to the supercharging pressure control.

  According to one embodiment of the present invention, if the detected engine speed is equal to or higher than the intercept speed, the throttle control means of the control device is configured to control the throttle valve with respect to the accelerator pedal opening as the detected engine speed increases. The throttle valve is controlled so that the change in the opening degree becomes steep.

  As the engine speed increases, the saturation throttle opening increases. According to the present invention, if the engine speed exceeds the intercept speed, the throttle valve is controlled so that the throttle opening more rapidly reaches the saturated throttle opening as the engine speed increases. With such control, when the engine speed is high, the engine output can be made to react quickly to an increase in the accelerator pedal opening.

  According to one embodiment of the present invention, the throttle control means of the control device further includes means for detecting atmospheric pressure. When the engine speed is the same, the throttle relative to the accelerator pedal opening degree decreases as the atmospheric pressure decreases. The throttle valve is controlled so that the change in the valve opening becomes gradual.

  The lower the atmospheric pressure, the higher the intercept rotation speed. When the intercept speed increases, the engine output that can be generated by the supercharger for a given engine speed decreases. According to the present invention, the throttle valve is controlled so that the throttle characteristic changes more gradually as the intercept speed increases. By such control, when the throttle control is switched to the supercharging pressure control, the engine output can be smoothly changed.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an internal combustion engine (hereinafter referred to as “engine”) and a control device according to an embodiment of the present invention.

  An electronic control unit (hereinafter referred to as “ECU”) 1 includes an input interface 1a that receives data sent from each part of the vehicle, a CPU 1b that executes calculations for controlling each part of the vehicle, and a read-only memory (ROM) ) And a random access memory (RAM) 1c and an output interface 1d for sending control signals to various parts of the vehicle. The ROM of the memory 1c stores a program for controlling each part of the vehicle and various data. The ROM may be a rewritable ROM such as an EPROM. The RAM is provided with a work area for calculation by the CPU 1b. Data sent from each part of the vehicle and control signals sent to each part of the vehicle are temporarily stored in the RAM.

  The engine 2 is an engine having, for example, four cylinders. An intake passage 3 is connected to the engine 2 via an intake valve 5. An exhaust passage 4 is connected to the engine 2 via an exhaust valve 6.

  A throttle valve 7 is provided in the intake passage 3. The throttle valve 7 adjusts the amount of air taken into the engine 2. The opening degree of the throttle valve 7 is controlled by a control signal from the ECU 1.

  The fuel injection valve 8 is provided for each cylinder between the engine 2 and the throttle valve 7. The fuel injection valve 8 injects the fuel supplied from the fuel tank in accordance with a control signal from the ECU 1.

  The turbocharger 9 includes a compressor 10 provided in the intake passage 3, a turbine 11 provided in the exhaust passage 4, and a rotating shaft 12 that connects the compressor 10 and the turbine 11. The turbine 11 is rotationally driven by the energy of the exhaust gas. The compressor 10 is rotated by the rotation of the turbine 11, and the compressor 10 generates compressed air.

  A supercharging pressure (Pc) sensor 13 is provided downstream of the compressor 10. The supercharging pressure sensor 13 detects the pressure of air generated by the compressor 10, that is, the supercharging pressure Pc, and sends this to the ECU 1.

  The chamber 15 is provided with an intake pipe pressure (Pb) sensor 14. The intake pipe pressure sensor 14 detects the pressure Pb of the air filled in the chamber 15 and sends it to the ECU 1.

  An electric waste gate valve 21 is provided in the exhaust passage 4. The opening degree of the electric waste gate valve 21 is controlled in accordance with a control signal from the ECU 1.

  As the opening degree of the waste gate valve 21 is increased, the amount of exhaust gas flowing into the bypass passage 22 is increased. As the amount of exhaust gas flowing through the bypass passage 22 increases, the rotation of the turbine 11 is suppressed, and the supercharging pressure generated by the compressor 10 becomes lower. By controlling the valve opening amount of the electric waste gate valve 21, the supercharging pressure can be controlled.

  A catalyst device 23 is provided in the exhaust passage 4. The catalyst device 23 purifies components such as HC, CO, NOx in the exhaust gas passing through the exhaust passage 4.

  The throttle valve opening sensor 25 is connected to the throttle valve 7. The throttle valve opening sensor 25 detects the opening of the throttle valve 7 and sends it to the ECU 1.

  The rotation speed (Ne) sensor 26 is attached around the cam shaft or crankshaft of the engine 2. The engine speed NE detected by the speed sensor 26 is sent to the ECU 1.

  The accelerator pedal opening sensor 27 detects the accelerator pedal opening AP and sends it to the ECU 1. The atmospheric pressure sensor 28 detects the atmospheric pressure PA and sends it to the ECU 1.

  The signal sent to the ECU 1 is passed to the input interface 1a and converted from analog to digital. The CPU 1b processes the converted digital signal according to a program stored in the memory 1c to generate a control signal. The output interface 1d sends these control signals to the throttle valve 7, the fuel injection valve 8, the electric wastegate valve 21, and other actuators.

  FIG. 2 shows a throttle characteristic 31 and a supercharging pressure characteristic 32 at a predetermined engine speed according to an embodiment of the present invention. The saturation throttle opening of the engine speed is represented by THs. The accelerator pedal opening APs is an accelerator pedal opening corresponding to the saturated throttle opening THs, and is hereinafter referred to as a saturated accelerator pedal opening.

  The accelerator pedal opening area until the accelerator pedal opening reaches the saturated accelerator pedal opening APs is referred to as a first area. In the first region, the throttle valve is controlled so that the throttle opening TH increases as the accelerator pedal opening AP increases. In the first region, the supercharging pressure control is not performed.

  Even after the throttle opening exceeds the saturation throttle opening THs, the throttle opening is increased according to the accelerator pedal opening. However, in this region, the engine output does not react to fluctuations in the throttle opening. The throttle opening is maintained at the fully open position after reaching the fully open position.

  Alternatively, after the throttle opening reaches the saturation throttle opening THs, the throttle opening may be maintained at the saturation throttle opening.

  In the second region where the accelerator pedal opening is larger than the saturated accelerator pedal opening APs, the supercharging pressure Pc generated by the supercharger is controlled to increase as the accelerator pedal opening AP increases.

  Thus, when the accelerator pedal opening reaches the saturated accelerator pedal opening APs, the throttle control is switched to the supercharging pressure control.

  When the pressure is lowered by increasing the pressure with the supercharger and reducing the amount of air with the throttle valve, the intake air temperature does not increase theoretically from the gas equation of state. However, since the heat insulation efficiency of the supercharger is low, the intake air temperature may rise above the value derived from the equation of state due to the influence of heat due to friction of the supercharger itself. This may cause knocking. By limiting the supercharging pressure control to the second region, knocking due to supercharging can be suppressed.

  FIG. 3 schematically shows engine output characteristics with respect to throttle opening. Each of reference numerals 41 to 44 indicates an engine output for each of the engine speeds NE1 to NE4. The engine speed shown is in the relationship NE1 <NE2 <NE3 <NE4.

  The saturation throttle opening at the engine speed NE1 is TH1. At the engine speed NE1, the engine output reaches the saturation point 45 when the throttle opening reaches the saturation throttle opening TH1. The saturation throttle opening at the engine speed NE2 is TH2. At the engine speed NE2, the engine output reaches the saturation point 46 when the throttle opening reaches the saturation throttle opening TH2. The saturation throttle opening at the engine speed NE3 is TH3. At the engine speed NE3, the engine output reaches the saturation point 47 when the throttle opening reaches the saturation throttle opening TH3. The saturation throttle opening at the engine speed NE4 is TH4. At the engine speed NE4, the engine output reaches the saturation point 48 when the throttle opening reaches the saturation throttle opening TH4.

  As described above, as the engine speed decreases, the saturation throttle opening decreases, and the engine output is saturated early. This is because as the engine speed decreases, the force for drawing air into the engine becomes weaker and the amount of air taken into the engine becomes smaller even when the throttle valve is opened.

  FIG. 4 shows (a) the intake pipe pressure characteristic 35 and (b) the engine output (engine torque) characteristic 36 generated by the supercharger when the vehicle is located in a lowland. The atmospheric pressure in the lowland is, for example, 101.3 kPa (= about 760 mmHg). The intercept speed is indicated by NE2, for example 2000 rpm.

  When the engine speed exceeds the intercept speed NE2, the supercharger is in a state where it can exert its capacity to the maximum. In this state, the maximum supercharging pressure can be generated, so that the engine output generated by the supercharger is maximized. Until the engine speed reaches the intercept speed NE2, the capacity of the supercharger is not maximized, and thus the generated engine output is low.

  If the engine speed is lower than the intercept speed when the throttle control is switched to the supercharging pressure control, the engine output may not increase smoothly because the generated supercharging pressure is low.

  In one embodiment of the present invention, the throttle characteristic described with reference to FIG. 2 is changed according to whether the engine speed is lower than the intercept speed. The change of the throttle characteristic will be described with reference to FIG.

  Referring to FIG. 5, there is shown a throttle characteristic when the vehicle is located in a lowland according to an embodiment of the present invention. Reference numeral 51 indicates a reference throttle characteristic when the engine speed is the intercept speed NE2. The saturation throttle opening at the intercept speed NE2 is TH2 as shown in FIG.

  According to the reference throttle characteristic 51, the saturation accelerator pedal opening corresponding to the saturation throttle opening TH1 of the engine speed NE1 is AP1. Even when the accelerator pedal opening is made larger than AP1 at the engine speed NE1, the engine output does not increase. The saturation accelerator pedal opening corresponding to the saturation throttle opening TH3 at the engine speed NE3 is AP3. At the engine speed NE3, even if the accelerator pedal opening is made larger than AP3, the engine output does not increase.

  A region where the engine output does not respond to fluctuations in the accelerator pedal opening is called a dead zone. The dead zone 55 at the engine speed NE1 is larger than the dead zone 54 at the intercept speed NE2. In the dead zone, even if the driver changes the accelerator pedal opening, the engine output does not react, which gives the driver an unpleasant feeling. It can be seen that the dead zone increases as the engine speed decreases.

  In an embodiment of the present invention, if the engine speed falls below the intercept speed NE2, the throttle characteristic is shifted in the direction of the arrow 57. Furthermore, in one embodiment of the present invention, the shift amount is increased as the engine speed becomes lower than the intercept speed. That is, the throttle valve is controlled so that the change in the throttle opening relative to the accelerator pedal opening becomes more gradual as the engine speed becomes lower than the intercept speed.

  When the engine speed decreases from the intercept speed NE2 to NE1, the throttle characteristic shifts from the line 51 to the line 52. According to the throttle characteristic 52, the accelerator pedal opening corresponding to the saturated throttle opening TH1 is AP2. As a result of the shift, it can be seen that the dead zone at the engine speed NE1 has the same size as the dead zone 54 at the intercept speed NE2. By shifting the throttle characteristic in the direction of arrow 57 in accordance with the decrease in engine speed, an increase in dead zone can be suppressed.

  By starting the supercharging pressure control when the accelerator pedal opening reaches the saturated accelerator pedal opening, it is possible to prevent the occurrence of a dead zone in the first region (see FIG. 2) as a result. If a dead zone is included in the first region, when the throttle control is switched to the supercharging pressure control, the engine output may start to react suddenly to a change in the accelerator pedal opening. This may cause discomfort to the driver. According to this embodiment, since the dead zone is prevented from occurring in the first region, it is possible to prevent the engine output from fluctuating when shifting from the throttle control to the supercharging pressure control.

  Further, this shift makes the engine output change more gradually with respect to the accelerator pedal opening as the engine speed becomes lower than the intercept speed. As described with reference to FIG. 4, when the engine speed is lower than the intercept speed, the engine output that can be generated by the supercharging pressure control is low. According to this embodiment, since the engine output generated by the throttle control is suppressed as the engine speed becomes lower than the intercept speed, the engine output is reduced when shifting from the throttle control to the supercharging pressure control. It can be raised smoothly.

  The shift of the throttle characteristic depends on where the saturation accelerator pedal opening corresponding to the saturation throttle opening is set. For example, when the engine speed is NE1, the throttle characteristic 52 is determined by setting the saturation accelerator pedal opening to AP2. The shift to the throttle characteristic 52 does not change the size of the dead zone. If the saturation accelerator pedal opening is set to AP3, the throttle characteristic is shifted to a line indicated by reference numeral 53. The shift to the throttle characteristic 53 reduces the size of the dead zone as indicated by reference numeral 56.

  A decrease in the dead zone means an increase in the first region. As the first area increases, the second area is reduced. When the engine speed is lower than the intercept speed, the engine output that can be generated by the supercharging pressure control greatly decreases as the engine speed decreases. Therefore, like the shift to the throttle characteristic 53 described above, the first region may be increased as the engine speed decreases, and the accelerator pedal region where the supercharging pressure control is performed may be reduced.

  In one embodiment of the present invention, if the engine speed exceeds the intercept speed NE1, the throttle characteristic is shifted in the direction opposite to the arrow 57. Furthermore, in one embodiment of the present invention, the shift amount is increased as the engine speed becomes higher than the intercept speed. That is, as the engine speed becomes higher than the intercept speed, the throttle valve is controlled so that the change in the throttle opening with respect to the accelerator pedal opening becomes steeper.

  When the engine speed increases from the intercept speed NE2 to NE3, the throttle characteristic shifts from the line 51 to the line 58. As a result of the shift, it can be seen that the dead zone at the engine speed NE3 has the same size as the dead zone 54 at the intercept speed NE2.

  The shift of the throttle characteristic in the direction opposite to the arrow 57 is also determined by where the saturation accelerator pedal opening corresponding to the saturation throttle opening is set. For example, when the engine speed is NE3, the throttle characteristic 58 is determined by setting the saturation accelerator pedal opening to AP2. Shifting to the throttle characteristic 58 does not change the size of the dead zone. If the saturation accelerator pedal opening is set to AP1, the throttle characteristic is represented by a line indicated by reference numeral 59. Shifting to the throttle characteristic 59 increases the size of the dead zone. However, by starting the supercharging pressure control at the saturated accelerator pedal opening AP1, it is possible to prevent the dead zone from occurring in the first region.

  A state in which the engine output does not increase rapidly with respect to an increase in the accelerator pedal opening despite the high engine speed may cause the driver to feel uncomfortable. According to this embodiment, as the engine speed increases with respect to the intercept speed, the engine output can be increased earlier and the supercharging pressure control can be started earlier. The supercharging pressure control is preferably performed so as not to cause a dead zone, which will be described later.

  On the other hand, the intercept rotation speed changes according to the atmospheric pressure. As the atmospheric pressure decreases, the intercept rotation speed increases. This is because, in order to achieve a given intake air amount, it is necessary to rotate the compressor at a higher rotational speed as the atmospheric pressure becomes lower.

  FIG. 6 shows (a) the intake pipe pressure characteristic 37 and (b) the engine output characteristic 38 when the vehicle is located at a high altitude. The atmospheric pressure in the highland is, for example, 66.6 kPa (= about 500 mmHg). For comparison, an engine output characteristic 36 (FIG. 4) when the vehicle is in a lowland (that is, when the atmospheric pressure is high) is shown. The intercept speed at high altitude is indicated by NE3, for example 2500 rpm. Further, for comparison, the intercept rotation speed NE2 when the vehicle is located in the lowland is shown.

  As is apparent from a comparison of the engine output characteristic 38 and the engine output characteristic 36, when the engine speed is lower than the intercept speed, the engine output at a given engine speed decreases as the atmospheric pressure decreases.

  Referring to FIG. 7, the throttle characteristic when the vehicle is located at a high altitude according to an embodiment of the present invention is shown. The reference throttle characteristic 71 is a throttle characteristic when the engine speed is the intercept speed NE3. As shown in FIG. 3, the saturation throttle opening at the intercept speed NE3 is TH3.

  In the same manner as described with reference to FIG. 5, when the engine speed falls below the intercept speed, the throttle characteristic shifts in the direction of arrow 77. As the engine speed becomes lower than the intercept speed, the shift amount is increased.

  When the engine speed exceeds the intercept speed, the throttle characteristic is shifted in the direction opposite to the arrow 77. As the engine speed becomes higher than the intercept speed, the shift amount is increased.

  As apparent from the comparison with FIG. 5, the slope of the reference throttle characteristic is the same between the lowland and the highland. However, it should be noted that the engine speed associated with the reference throttle characteristic is different. When comparing the throttle characteristics in the low altitude and the throttle characteristics in the high altitude at a given engine speed, the slope of the throttle characteristics in the high altitude is gentler than that in the low altitude. For example, when the engine speed is 2000 rpm, the low altitude shown in FIG. 5 is represented by the throttle characteristic 51, whereas the high altitude shown in FIG. The

  The lower the atmospheric pressure, the lower the engine output that can be generated by the supercharger when the supercharging pressure control is started. According to the embodiment of the present invention, the lower the atmospheric pressure, the more the engine output generated by the throttle control is suppressed. Therefore, the engine output can be changed smoothly when shifting from the throttle control to the supercharging pressure control. it can.

  As in FIG. 5, the shift of the throttle characteristic is determined by where the saturation accelerator pedal opening corresponding to the saturation throttle opening is set. For example, when the engine speed falls below the intercept speed NE3, the throttle characteristic 72 is determined by setting the saturation accelerator pedal opening to AP3. The dead zone of the throttle characteristic 72 has the same size as the dead zone 74 of the reference throttle characteristic 71. If the saturation accelerator pedal opening is set to AP4, the throttle characteristic is shifted to a line indicated by reference numeral 73. Shifting to the throttle characteristic 73 reduces the size of the dead zone, as indicated by reference numeral 76.

  When the engine speed is NE4 higher than the intercept speed, the throttle characteristic 78 is determined by setting the saturation accelerator pedal opening to AP3. The dead zone of the throttle characteristic 78 has the same size as the dead zone 74 of the reference throttle characteristic 71. If the saturation accelerator pedal opening is set to AP2, the throttle characteristic is shifted to a line indicated by reference numeral 79. The shift to the throttle characteristic 79 increases the size of the dead zone as indicated by reference numeral 75. However, by starting the supercharging pressure control at the saturated accelerator pedal opening AP2, it is possible to prevent the dead zone from occurring in the first region. In the second region, it is preferable that the supercharging pressure control is performed so that no dead zone occurs.

  FIG. 8 shows a functional block diagram of throttle / supercharging pressure control according to an embodiment of the present invention.

  The selector 110 selects either throttle control or supercharging pressure control based on the accelerator pedal opening AP detected by the accelerator pedal opening sensor 27 (FIG. 1).

  The throttle control unit 111 refers to the map based on the accelerator pedal opening AP detected by the accelerator pedal opening sensor 27 (FIG. 1) and the engine speed NE detected by the engine speed sensor 26 (FIG. 1). Then, the target throttle opening TH_cmd is calculated.

  An example of this map is shown in FIG. A map (a) for high atmospheric pressure (in this example, 101.3 kPa (= about 760 mmHg)) and a map (b) for low atmospheric pressure (in this example, 66.6 kPa (= about 500 mmHg)) It is prepared. It is assumed that the intercept rotation speed at high atmospheric pressure is 2000 rpm, and the intercept rotation speed at low atmospheric pressure is 2500 rpm.

  The throttle characteristics 81, 82, 83 and 84 in the map (a) show the throttle characteristics at engine speeds of 1000, 1500, 2000 and 2500 rpm, respectively. The throttle characteristics 85, 86, 87 and 88 in the map (b) indicate the throttle characteristics at engine speeds of 1500, 2000, 2500 and 3000 rpm, respectively.

  The saturation throttle opening is indicated by a black circle. As described above, the saturation throttle opening decreases as the engine speed decreases. In the map (a), the saturation accelerator pedal opening corresponding to the saturation throttle opening in the throttle characteristics 81, 82, 83 and 84 is represented by APsh1, APsh2, APSh3 and APSh4, respectively. In the map (b), the saturation accelerator pedal opening corresponding to the saturation throttle opening in the throttle characteristics 85, 86, 87, and 88 is represented by APsl2, APsl3, APsl4, and APsl5, respectively.

  For example, when comparing the throttle characteristics 83 and 86 when the engine speed is 2000 rpm, the saturated throttle opening is the same. However, the slopes of the throttle characteristics 83 and 86 differ depending on the difference in the intercept rotation speed, and the saturation accelerator pedal opening is APsh3 and APsl3, respectively.

  Preferably, as shown in the maps (a) and (b), the shift amount for the throttle characteristic when the engine speed is higher than the intercept speed is made smaller than when the engine speed is lower than the intercept speed. The For example, in the map (a), the shift amount from the reference throttle characteristic 83 to the throttle characteristic 84 when the engine speed is 2500 rpm is from the reference throttle characteristic 83 to the throttle characteristic 82 when the engine speed is 1500 rpm. Less than the shift amount.

  The reason for this will be briefly explained. When the engine speed is lower than the intercept speed, the lower the engine speed, the lower the supercharging capability and the smaller the saturation throttle opening. In consideration of a decrease in engine output due to these two factors, it is preferable that the shift amount of the throttle characteristic is set to be large. On the other hand, when the engine speed is higher than the intercept speed, the supercharging capability can be maximized, so the only factor to be considered is the saturated throttle opening. Since there is no need to consider a decrease in engine output due to insufficient supercharging capability, the amount of shift in the throttle characteristic can be reduced compared to when the engine speed is lower than the intercept speed.

  In this map, the saturation accelerator pedal opening is set so that the first region increases as the engine speed decreases. With this setting, the dead zone decreases as the engine speed decreases. However, as described above, the size of the first region may not be changed as the engine speed decreases.

  Returning to FIG. 8, the throttle control unit 111 refers to the high atmospheric pressure map (a) to determine the throttle opening corresponding to the detected accelerator pedal opening AP and the detected engine speed NE. For example, when the engine speed NE is 1500 rpm, the throttle opening THh is calculated. Similarly, the throttle control unit 111 refers to the low atmospheric pressure map (b) to determine the throttle opening corresponding to the detected accelerator pedal opening AP and the engine speed NE. When the engine speed NE is 1500 rpm, the throttle opening THl is calculated. Interpolation calculation is performed on the calculated THh and THl, and a target throttle opening TH_cmd corresponding to the atmospheric pressure PA detected by the atmospheric pressure sensor 28 (FIG. 1) is calculated.

  The throttle control unit 111 controls the throttle valve 7 (FIG. 1) so that the throttle valve opening TH converges to the target throttle opening TH_cmd.

  The supercharging pressure control unit 112 refers to the map based on the detected accelerator pedal opening AP and the engine speed NE, and calculates a target supercharging pressure Pc_cmd. An example of this map is shown in FIG. The map (a) for the high atmospheric pressure (in this example, 101.3 kPa (= about 760 mmHg)) in FIG. 9 is used together with the map (a) in FIG. The map (b) for the low atmospheric pressure (in this example, 66.6 kPa (= about 500 mmHg)) in FIG. 9 is used together with the map (b) in FIG.

  Reference numbers 91, 92, 93, and 94 indicate the supercharging pressure characteristics at engine speeds of 1000, 1500, 2000, and 2500 rpm, as in the map (a) of FIG. Reference numerals 95, 96, 97, and 98 indicate the supercharging pressure characteristics at engine speeds of 1500, 2000, 2500, and 3000 rpm, as in the map (b) of FIG. In each supercharging pressure characteristic, supercharging pressure control is started when the accelerator pedal opening reaches the saturated accelerator pedal (APsh1 to APs15).

  As indicated by line 94 in FIG. 10 (a) and line 98 in FIG. 10 (b), when the engine speed is higher than the intercept speed, the maximum target when the target boost pressure is the intercept speed. Note that it converges to supercharging pressure. When the engine speed reaches the intercept speed, the maximum boost pressure can be generated. If the lines 94 and 98 are inclined in the same manner as other boost pressure characteristics such as the line 93, the target boost pressure reaches the maximum boost before the accelerator pedal opening reaches 100%, as shown by the dotted line 100. The supply pressure will be reached. This creates a dead zone as indicated by reference numeral 101. In order to avoid this, the supercharging pressure is controlled so that the change of the supercharging pressure with respect to the accelerator pedal opening becomes more gradual as the engine speed becomes higher than the intercept speed.

  The supercharging pressure control unit 112 obtains a target supercharging pressure corresponding to the detected accelerator pedal opening AP and engine speed NE with reference to the map (a) for high atmospheric pressure. For example, when the engine speed NE is 1500 rpm, the supercharging pressure Pch is calculated. Similarly, the supercharging pressure control unit 112 obtains a target supercharging pressure corresponding to the detected accelerator pedal opening AP and the engine speed NE with reference to the low atmospheric pressure map (b). For example, when the engine speed NE is 1500 rpm, the supercharging pressure Pcl is calculated. Interpolation calculation is performed on the calculated Pch and Pcl, and a target boost pressure Pc_cmd corresponding to the atmospheric pressure PA detected by the atmospheric pressure sensor 28 (FIG. 1) is calculated.

  The supercharging pressure control unit 112 controls the electric waste gate valve 21 (FIG. 1) so that the supercharging pressure Pc converges to the target supercharging pressure Pc_cmd.

  FIG. 11 shows a flowchart of throttle control and supercharging pressure control according to an embodiment of the present invention.

  In step S1, based on the detected accelerator pedal opening AP and the detected engine speed NE, a map for high atmospheric pressure as shown in FIG. Ask.

  In step S2, on the basis of the detected accelerator pedal opening AP and the detected engine speed NE, a map for low atmospheric pressure as shown in FIG. Ask.

  In step S3, interpolation calculation is performed based on the throttle openings THh and THl, and a target throttle opening TH_cmd based on the detected atmospheric pressure PA is calculated. Of course, if a map for the detected atmospheric pressure is prepared, the target throttle opening TH_cmd can be obtained by referring to only the map.

  In step S4, based on the detected accelerator pedal opening AP and the detected engine speed NE, a map for high atmospheric pressure as shown in FIG. Ask.

  In step S5, based on the detected accelerator pedal opening AP and the detected engine speed NE, a superatmospheric pressure Pcl is determined by referring to a map for low atmospheric pressure as shown in FIG. Ask.

  In step S6, a target boost pressure Pc_cmd based on the detected atmospheric pressure PA is calculated based on the boost pressures Pch and Pcl. Of course, if a map for the detected atmospheric pressure is prepared, the target boost pressure can be obtained by referring only to the map.

  In step S7, the detected throttle opening TH is compared with the target throttle opening TH_cmd calculated in step S3. If TH> TH_cmd, the throttle valve is controlled to close to converge the throttle valve opening to the target throttle opening (S8). If TH <TH_cmd, the throttle valve is controlled to open to converge the throttle valve opening to the target throttle opening (S9). If TH = TH_cmd, the throttle valve is maintained at the current opening.

  In step S10, the boost pressure Pc detected by the boost pressure sensor 13 (FIG. 1) is compared with the target boost pressure Pc_cmd. If Pc> Pc_cmd, the direction of opening the wastegate valve is controlled to converge the supercharging pressure to the target supercharging pressure (S11). If Pc <Pc_cmd, control is performed so that the wastegate valve is closed, and the supercharging pressure is converged to the target supercharging pressure (S12). If Pc = Pc_cmd, the wastegate valve is maintained at the current valve opening.

  In the flowchart of FIG. 11, both the throttle control map shown in FIG. 9 and the boost pressure control map shown in FIG. 10 are referred to. Alternatively, a step for realizing the selector function as shown in FIG. 8 is provided, and either the throttle control map or the boost pressure control map is referred to based on the detected accelerator pedal opening. You may do it.

  In step S10 of the flowchart of FIG. 11, the boost pressure detected by the boost pressure sensor is compared with the target boost pressure. Alternatively, when the supercharging pressure control is performed, if the throttle valve is fully opened, the intake pipe pressure detected by the intake pipe pressure sensor may be compared with the target supercharging pressure.

  In the above embodiment, a turbocharger is used to perform supercharging. Alternatively, other superchargers may be used. For example, a supercharger that rotates the compressor by the driving force of the engine can be used. Moreover, you may combine the supercharger of a different system. The saturation accelerator pedal opening may be set in consideration of the performance of the supercharger used, or may be set in consideration of the supercharging characteristic with respect to the accelerator pedal opening.

  It should be noted that the term intercept rotational speed in this specification is not used to limit the present invention to a turbocharger. That is, in the present specification, when the supercharging pressure characteristic changes according to the engine speed, the intercept speed is used as a term representing the engine speed at which the boost pressure rises and can reach the maximum value. . Therefore, for example, when a supercharger is used, the engine speed at which the supercharging pressure generated by the supercharger can reach the maximum is the intercept speed.

  The control for converging the boost pressure to the target boost pressure may be realized by any other appropriate method. A mechanical wastegate valve may be used instead of the electric wastegate valve. The mechanical wastegate valve opens when the pressure of the exhaust gas reaches a predetermined value and releases the exhaust gas. The supercharging pressure can be controlled, for example, by assisting the driving of the compressor with a motor.

  The present invention can also be applied to a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

1 schematically shows an internal combustion engine, a supercharger, and a control device according to one embodiment of the present invention. FIG. The figure which shows switching of throttle control and supercharging pressure control according to one Embodiment of this invention. The figure which shows the engine output characteristic with respect to throttle opening. The figure which shows the intake pipe pressure and engine output which change according to an engine speed when a vehicle is located in a lowland. The figure which shows the throttle characteristic when the vehicle is located in a lowland according to one Embodiment of this invention. The figure which shows the intake pipe pressure and engine output which change according to an engine speed when a vehicle is located in a highland. The figure which shows the throttle characteristic when the vehicle is located in a highland according to one Embodiment of this invention. The functional block diagram of throttle control and supercharging pressure control according to one embodiment of this invention. (A) A map defining throttle characteristics for high atmospheric pressure, and (b) A map defining throttle characteristics for low atmospheric pressure, according to one embodiment of the present invention. (A) A map that prescribes a supercharging pressure characteristic for high atmospheric pressure, and (b) a map that prescribes a supercharging pressure characteristic for low atmospheric pressure, according to one embodiment of the present invention. The flowchart of throttle control and supercharging pressure control according to one embodiment of this invention.

Explanation of symbols

1 ECU
2 Engine 7 Throttle valve 9 Turbocharger 27 Accelerator pedal opening sensor 28 Atmospheric pressure sensor

Claims (5)

An apparatus for controlling the output of an internal combustion engine equipped with a supercharger,
A throttle valve for adjusting the amount of air taken into the internal combustion engine;
A rotational speed detection means for detecting the rotational speed of the internal combustion engine;
Accelerator pedal opening detection means for detecting the opening of the accelerator pedal;
If the detected accelerator pedal opening is equal to or less than a saturated accelerator pedal opening set in accordance with the throttle valve opening at which the output of the internal combustion engine is saturated , based on the detected accelerator pedal opening, Throttle control means for controlling the opening of the throttle valve;
If the detected accelerator pedal opening is larger than the saturated accelerator pedal opening, a supercharging pressure control means for controlling a supercharging pressure generated by the supercharger based on the detected accelerator pedal opening. And comprising
If the detected rotational speed is lower than the interceptor rotational speed of the supercharger , the throttle control means is configured so that the throttle valve opening relative to a given accelerator pedal opening is lower than a reference opening. Control
The reference opening is an opening of a throttle valve with respect to the given accelerator pedal opening when the rotation speed of the internal combustion engine is the intercept rotation speed.
A device that controls the output of an internal combustion engine. The throttle control means further includes
If the detected engine rotational speed is lower than the intercept rotational speed , the change in the throttle valve opening relative to the change in the accelerator pedal opening is moderated as the detected engine rotational speed decreases. Control the throttle valve,
The apparatus for controlling the output of the internal combustion engine according to claim 1. The throttle control means further includes
If the detected engine speed is equal to or higher than the intercept speed , the change in the throttle valve opening with respect to the change in the accelerator pedal opening becomes steeper as the detected engine speed increases. Control the throttle valve,
The apparatus for controlling the output of the internal combustion engine according to claim 1. A means for detecting atmospheric pressure;
The throttle control means further controls the throttle valve so that the change in the throttle valve opening relative to the change in the accelerator pedal opening becomes more gradual as the detected atmospheric pressure becomes lower.
The apparatus which controls the output of the internal combustion engine in any one of Claim 1 to 3. further,
If the detected accelerator pedal opening is equal to or less than the saturated accelerator pedal opening , the control of the output of the internal combustion engine by the throttle control means is selected, and the detected accelerator pedal opening is greater than the saturated accelerator pedal opening . wherein Ru comprising a selection means for selecting a control output of the internal combustion engine by the supercharging pressure control means is larger,
The apparatus which controls the output of the internal combustion engine in any one of Claim 1 to 4.

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