JP2009085186A - Internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of restraining unstable supercharging pressure or back pressure due to hysteresis of a nozzle vane in an internal combustion engine with a supercharger. <P>SOLUTION: This internal combustion engine 1 with a variable capacity type turbocharger 50 comprises a drive source 56 connected with a nozzle vane and driving the nozzle vane, and drive source control means 10 giving a command value corresponding to an opening degree according to a target opening degree to the drive source when a variation of the opening degree making the opening degree of the nozzle vane large to attain the target opening degree is below a predetermined value, and giving a command value corresponding to the target opening degree to the drive source after the command value corresponding to the opening degree much larger than the target opening degree is given to the drive source when the variation is not less than the predetermined value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a supercharged internal combustion engine.

  In the internal combustion engine, if a turbocharger that is driven by using the energy of the exhaust gas discharged from the internal combustion engine is provided, the charging efficiency of the combustion chamber can be increased and the engine output can be further increased.

  The variable displacement turbocharger increases the flow rate of the exhaust gas and increases the rotational speed and rotational force of the turbine by rotating the nozzle vane in the closing direction even when the amount of exhaust gas is small, such as in the low rotation operation region of the internal combustion engine. Can be increased. Thereby, even when the amount of exhaust is small, the charging efficiency of the internal combustion engine can be increased.

  By the way, the nozzle vane is driven from the outside of the exhaust passage via the vane shaft. This vane shaft is rotated by, for example, a drive ring connected to a link mechanism. Since each of these members needs to move smoothly when transmitting force, a certain amount of play is provided between the members. Therefore, when each member transmits a force, it first moves by the amount of play, and then the force is transmitted after moving by the amount of play. That is, the force from a drive source such as an actuator is not immediately transmitted to the nozzle vane. In addition, since it becomes difficult for force to be transmitted due to this play, even if an actuator or the like is operated, if the operation amount is small, the force may not be transmitted to the nozzle vane and the nozzle vane may not move. Thus, hysteresis occurs in the nozzle vane.

  Here, the back pressure can be adjusted by opening and closing the nozzle vanes. However, even if the actuator is operated in the direction to open the nozzle vane in order to lower the back pressure after the nozzle vane is closed, the opening degree of the nozzle vane may not increase due to the play. That is, when the back pressure becomes excessively high, the supercharging pressure may become excessively high.

  A technique is known in which a skip value for correcting hysteresis of an actuator that drives an exhaust gas switching valve is added to a duty ratio during duty control of the exhaust gas switching valve (see, for example, Patent Document 1).

However, when such control is applied to the nozzle vane, the supercharging pressure may be excessively decreased or the back pressure may be excessively increased by opening the nozzle vane too much.
Japanese Patent Laid-Open No. 3-275941 JP-A-5-099027 JP-A-7-158476 JP-A-9-170477 JP 2004-36520 A

  The present invention has been made in view of the above-described problems, and provides a technology capable of suppressing the supercharging pressure or the back pressure from becoming unstable due to the hysteresis of the nozzle vanes in an internal combustion engine with a supercharger. For the purpose.

In order to achieve the above object, an internal combustion engine with a supercharger according to the present invention comprises:
In an internal combustion engine equipped with a variable displacement turbocharger that changes a flow rate of exhaust gas blown to a turbine by changing a nozzle vane angle so that a supercharging pressure becomes a desired pressure.
A drive source connected to the nozzle vane for driving the nozzle vane;
When the amount of change in the opening until the nozzle vane opening is increased to the target opening is less than a predetermined value, a command value corresponding to the opening corresponding to the target opening is given to the drive source, and the predetermined value or more Drive source control means for giving a command value corresponding to the target opening to the drive source after giving a command value corresponding to an opening larger than the target opening to the drive source,
It is characterized by providing.

  Here, the target opening is, for example, an opening for obtaining a target supercharging pressure, an opening for obtaining a target back pressure, or an opening for obtaining a target turbine speed. can do. The command value is a command given to operate the drive source, and the drive source operates according to the command value. The opening degree of the nozzle vane is adjusted by the operation of the drive source.

  And if the opening degree of a nozzle vane is enlarged from the present time, since the resistance by this nozzle vane will become small, a back pressure will fall. However, even if the drive source is operated to move the nozzle vane, force may not be transmitted to the nozzle vane due to play provided between the members. That is, even if a command value corresponding to an opening larger than the target opening of the nozzle vane is given to the drive source, the actual opening of the nozzle vane does not change by the amount of play provided between the members. On the other hand, for example, the actual opening degree of the nozzle vane can be adjusted to the target opening degree by giving a command value so that the drive source operates more by the play provided between the members.

  Then, by giving a command value corresponding to the target opening to the drive source after that, when moving the nozzle vane to the side to reduce the opening, after each member has moved by the amount of play between each member, The force from the drive source can be quickly transmitted. That is, the opening degree of the nozzle vane can be quickly reduced by eliminating play on the side of reducing the opening degree of the nozzle vane.

  Further, the drive source control means provides a command value corresponding to an opening larger than the target opening when the amount of change in the opening when the opening of the nozzle vane is increased to the target opening is a predetermined value or more. It is given to the drive source. That is, when the amount of change in opening when the target opening is set is less than a predetermined value, a command value corresponding to the target opening at that time is given to the drive source. If the opening degree of the nozzle vane is once increased in order to slightly move the nozzle vane, the effect on the supercharging pressure is large. That is, even if the supercharging pressure of the internal combustion engine is adjusted to the target value by slightly moving the nozzle vane, there is a possibility that the supercharging pressure fluctuates until reaching the target value. Therefore, there are cases where it is possible to maintain a better operating state if the nozzle vanes are not moved in a range that does not significantly affect the operating state.

  The predetermined value is set as a range in which it is better not to move the nozzle vane. This predetermined value may be, for example, the amount of change in opening corresponding to the total play of each member. That is, when the amount of change in the target opening is within the range of play of each member, the command value corresponding to the target opening is directly given to the drive source.

In order to achieve the above object, an internal combustion engine with a supercharger according to the present invention comprises:
In an internal combustion engine equipped with a variable displacement turbocharger that changes a flow rate of exhaust gas blown to a turbine by changing a nozzle vane angle so that a supercharging pressure becomes a desired pressure.
A drive source connected to the nozzle vane for driving the nozzle vane;
When the opening degree of the nozzle vane is increased to the target opening degree, a command value corresponding to an opening degree larger than the target opening degree is given to the driving source, and then the command value corresponding to the target opening degree is used as the driving source. Drive source control means for providing,
A supercharging pressure measuring means for measuring the supercharging pressure;
The actual boost pressure when a command value corresponding to an opening larger than the target opening is given to the drive source is compared with the target boost pressure so that the actual pressure approaches the target pressure. Learning means for learning a command value corresponding to an opening larger than the target opening;
It is good also as comprising.

  Here, the amount of play of each member (hereinafter, also referred to as the magnitude of hysteresis generated in the nozzle vane) changes with time, individual differences, temperature, and the like. That is, the optimum value of the command value when the command value corresponding to an opening larger than the target opening is given in consideration of hysteresis may change. Therefore, if a constant command value is always given, the command value becomes larger than the amount of play, so that the opening degree of the nozzle vane may be excessively increased, which may cause the supercharging pressure to decrease too much.

  Therefore, the learning means corrects the command value so as to reduce the difference between the actual supercharging pressure and the target supercharging pressure, and stores this as a learning value. In the subsequent nozzle vane control, this learning value is used.

  Here, when the actual supercharging pressure is lower than the target supercharging pressure, the nozzle vane is opened too much, so that the command value is corrected in a direction in which the opening becomes smaller. Thereby, it can suppress that supercharging pressure becomes lower than necessary.

  In the present invention, when the load of the internal combustion engine changes from a low load to a predetermined medium load or more, the drive source control means sends a command value corresponding to an opening larger than the current opening to the drive source. After the application, the command value corresponding to the current opening can be given to the drive source.

  Here, when the amount of change in the opening when the opening of the nozzle vane is increased to the target opening is less than a predetermined value, a command value corresponding to the opening corresponding to the target opening is given to the drive source. . In this case, the actual opening of the nozzle vane does not change. Thus, even if the opening degree of the nozzle vane does not change, the back pressure hardly increases at a low load of the internal combustion engine. However, since the amount of exhaust gas increases when the internal combustion engine is operated at a medium load or higher, the back pressure may increase excessively unless the nozzle vane opening is actually changed. On the other hand, when the internal combustion engine is operated at a medium load or higher, it corresponds to a larger opening than the target opening regardless of the amount of change in the opening when the opening of the nozzle vane is increased to the target opening. By giving a command value corresponding to the target opening to the drive source after giving the command value to the drive source, an increase in back pressure can be suppressed.

  However, at a low load of the internal combustion engine, the load of the internal combustion engine becomes higher than the medium load after the amount of change in the opening when the nozzle vane opening is increased to the target opening is less than a predetermined value. In such a case, the load becomes high in a state where the actual opening degree of the nozzle vane is smaller than the target opening degree. As described above, when the nozzle vane is not actually opened to the target opening, but the load is increased assuming that the nozzle is at the target opening, the back pressure increases.

  As described above, the back pressure did not increase without moving the nozzle vane if the difference between the actual opening and the target opening was less than the predetermined value at low load, but at low load at low load. Even if the difference in opening is not a problem, the back pressure may be increased.

Therefore, when the load on the internal combustion engine changes from a low load to a predetermined medium load or higher, even if there is no change in the target opening, a command value corresponding to a larger opening than the current opening is driven. After giving to the power source, the command value corresponding to the current opening is given to the driving source. Thereby, since the opening degree of a nozzle vane turns into a target opening degree, the raise of a back pressure can be suppressed.

  The predetermined medium load or more may be a load that may cause the back pressure to rise above an allowable value when the actual opening degree of the nozzle vane is not the target opening degree.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a supercharging pressure or a back pressure becomes unstable by the hysteresis of a nozzle vane in an internal combustion engine with a supercharger.

  Hereinafter, specific embodiments of an internal combustion engine with a supercharger according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 1 and its intake / exhaust system according to the present embodiment. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders 2.

  An intake passage 3 and an exhaust passage 4 are connected to the internal combustion engine 1. The intake passage 3 is connected to the cylinder 2 via an intake port 2A, and the exhaust passage 4 is connected to the cylinder 2 via an exhaust port 2B.

  Further, the internal combustion engine 1 according to this embodiment includes a variable displacement turbocharger 50 (hereinafter simply referred to as “turbocharger 50”). The turbocharger 50 includes a compressor housing 51, a turbine housing 52, and a center housing 53. The compressor housing 51 is provided in the middle of the intake passage 3, and the inside of the compressor housing 51 constitutes a part of the intake passage 3. The turbine housing 52 is provided in the middle of the exhaust passage 4, and the interior of the turbine housing 52 constitutes a part of the exhaust passage 4. The compressor housing 51 and the turbine housing 52 are connected via a center housing 53.

  The turbine housing 52 is provided with a link chamber 54 for storing a part of a link mechanism 80 for rotating a nozzle vane 73 to be described later. The link mechanism 80 in the link chamber 54 is connected via a link rod 55. The actuator 56 is connected.

  Next, a specific configuration of the turbocharger 50 will be described with reference to FIG. Here, FIG. 2A is a cross-sectional view showing the configuration of the turbocharger 50, and FIG. 2B is a view showing the variable nozzle mechanism 70 of the turbocharger 50.

  As described above, the turbocharger 50 includes the compressor housing 51, the turbine housing 52, and the center housing 53.

  The compressor housing 51 is provided with a compressor 60 having a plurality of wings, and the turbine housing 52 is provided with a turbine 61 having a plurality of wings. The compressor 60 and the turbine 61 are connected via a rotor shaft 62.

  A spiral scroll chamber 63 surrounding the outer periphery of the turbine 61 is formed in the turbine housing 52.

  Further, a variable nozzle mechanism 70 is housed in the turbine housing 52. The variable nozzle mechanism 70 includes a ring plate 71 formed in a ring shape as shown in FIG. The ring plate 71 is fixed to the turbine housing 52 by bolts (not shown). The ring plate 71 is provided with a plurality of vane shafts 72 at equal angles around the center of the ring plate 71.

  Each vane shaft 72 is rotatably supported through the ring plate 71 in the thickness direction. A nozzle vane 73 is fixed to one end of each vane shaft 72 on the scroll chamber 63 side. On the other hand, a vane arm 74 that is orthogonal to the vane shaft 72 and extends to the outer edge of the ring plate 71 is fixed to the other end of the vane shaft 72. The vane shaft 72 and the vane arm 74 are integrally rotatable around the central axis of the vane shaft 72.

  An annular drive ring 75 is provided between each vane arm 74 and the ring plate 71 so as to overlap the ring plate 71. The drive ring 75 is rotatable in the circumferential direction about the circle center. Further, the drive ring 75 is provided with a holding portion 76, and the end portion of the vane arm 74 extending to the outer edge side of the ring plate is held by the holding portion 76. In the sandwiching portion 76, the end portion of the vane arm 74 is sandwiched so as to be rotatable and slidable in the diameter direction of the drive ring 75.

  In the variable nozzle mechanism 70 configured as described above, when the drive ring 75 rotates around the center of the circle, the end of the vane arm 74 held by the holding unit 76 also tries to rotate together. However, since the vane arm 74 can only rotate about the vane shaft 72, the end of each vane arm 74 moves in the diameter direction of the drive ring 75 within the holding portion 76 while rotating about the vane shaft 72. As a result, the vane arm 74 rotates the vane shaft 72, and the nozzle vane 73 rotates around the vane shaft 72 in synchronization with the rotation of the vane shaft 72.

  Next, the link mechanism 80 that drives the variable nozzle mechanism 70, that is, rotationally drives the drive ring 75 will be described. The drive ring 75 is provided with a drive arm clamping portion 82 that clamps one end of a drive arm 81 having the same shape as the vane arm 74. The drive arm clamping part 82 clamps one end of the drive arm 81 slidably and rotatably like the clamping part 76.

  Then, one end side of a link shaft 83 having a central axis in the same direction as the central axis of the vane shaft 72 is fixed to the other end side of the drive arm 81. The link shaft 83 extends toward the compressor housing 51 and passes through the center housing 53. That is, the other end of the link shaft 83 is exposed to the atmosphere. The link shaft 83 is rotatably supported by a guide 91 press-fitted into the center housing 53. A part of the other end side of the link shaft 83 extends in a direction perpendicular to the rotation axis of the link shaft 83 to form a drive link 84. A pin 85 having an axis parallel to the rotation axis of the link shaft 83 is fixed to the drive link 84. Further, the pin 85 supports the link rod 55 in a rotatable manner.

In the variable nozzle mechanism 70 configured as described above, the drive link 84 is rotated about the link shaft 83 by the forward / backward movement of the link rod 55 connected to the actuator 56. When the drive link 84 is rotated, the link shaft 83 rotates in synchronization therewith, and the drive arm 81 rotates around the link shaft 83 as the link shaft 83 rotates. As a result, the drive arm 81 pushes the drive ring 75 in the circumferential direction and rotates the drive ring 75.

  In the turbocharger 50 described above, the direction of the flow path between the nozzle vanes 73 and the gap between the nozzle vanes 73 can be changed by adjusting the rotation direction and the rotation amount of the nozzle vanes 73 by the link mechanism 80. Become. That is, by controlling the rotation direction and the rotation amount of the nozzle vane 73, the direction and flow velocity of the exhaust blown from the scroll chamber 63 to the turbine 61 are adjusted. In this embodiment, the actuator 56 corresponds to the drive source in the present invention.

  A pressure sensor 11 that measures the pressure in the intake passage 3 is attached to the intake passage 3 downstream of the compressor housing 51. The supercharging pressure is measured by the pressure sensor 11. In this embodiment, the pressure sensor 11 corresponds to the supercharging pressure measuring means in the present invention.

  The internal combustion engine 1 configured as described above is provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 10 is a unit that controls the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the driver's request.

  A pressure sensor 11 is connected to the ECU 10 via an electric wiring, and an electric signal from the pressure sensor 11 is input to the ECU 10. The ECU 10 is connected with an actuator 56 and the like via electric wiring, and the above-described units can be controlled by the ECU 10.

  By the way, before the actuator 56 operates and the nozzle vane 73 moves, force is transmitted between many members constituting the variable nozzle mechanism 70 and the link mechanism 80. Between these members, a gap or play for smoothly transmitting force is provided. For example, the play between the vane arm 74 and the holding part 76 and the play between the drive arm 81 and the drive arm holding part 82 are relatively large. Therefore, when the drive arm 81 rotates in one direction and then in the other direction, the drive ring 75 does not rotate immediately after the drive arm 81 rotates in the other direction. Similarly, when the drive ring 75 rotates in one direction and then in the other direction, the vane arm 74 does not rotate immediately after the drive ring 75 rotates in the other direction.

  That is, when the operating direction of the actuator 56 is reversed, the force is transmitted to the next member after the amount of play moves in each member. Therefore, the amount of movement of the nozzle vane 73 is less than the amount of play between the members with respect to the amount of movement of the actuator 56. Thereby, the adjustment of the back pressure is delayed, and the back pressure may be higher than the target value.

  On the other hand, in this embodiment, when the nozzle vane 73 is moved to the opening side after being moved to the closing side, the actuator 56 is operated to the opening side by an amount equal to or more than the sum of the play of each member, and then the actuator 56 is moved. Actuate to the closing side.

Here, FIG. 3 is a diagram showing the relationship between the control command value of the actuator 56 and the back pressure. The control command value of the actuator 56 is a signal given from the ECU 10 to the actuator 56. The actuator 56 operates by an amount corresponding to the control command value. When it is assumed that there is no play between the members, the control command value of the actuator 56 and the opening degree of the nozzle vane 73 correspond to each other. That is, the value corresponding to the fully closed nozzle vane 73 is 0%, and the value corresponding to the fully opened nozzle vane 73 is 100%. When it is assumed that there is no play between the members, when the actuator 56 is operated with the control command value of the actuator 56 as a target value, the nozzle vane 73 reaches the target opening. FIG. 3 shows a case where the total amount of play between the members is 5% of the control command value of the actuator 56. The control command value of the actuator 56 corresponding to the total play is referred to as “control hysteresis”. The control command value of the actuator 56 corresponding to the target opening of the nozzle vane 73 is referred to as a target value.

  Here, when the control command value of the actuator 56 is changed from 40% to 0%, for example, the nozzle vane 73 is closed, so that the back pressure rises through points A, B, C, and D in order. Thereafter, when the control command value of the actuator 56 is changed from 0% to 40%, the back pressure decreases in order through points D, E, F, G, and A. For example, when the opening degree of the nozzle vane 73 is opened 10% from the fully closed state, if the control command value of the actuator 56 is changed from 0% to 10%, the actual opening degree of the nozzle vane 73 is the first 5%. Almost unchanged.

  Here, when it is desired to lower the back pressure from X to Y, if the control command value of the actuator 56 is simply set as the target value, the back pressure only changes from D to E, so the back pressure at that time is X remains unchanged. On the other hand, in this embodiment, when the control command value of the actuator 56 is changed from 0% to 10%, it is once changed from 0% to 25%, for example, and then returned to 10%. That is, the control command value of the actuator 56 is increased by an extra 15%. As a result, the back pressure sequentially passes through points D, E, F, and C. Therefore, the back pressure drops from X to Y.

  The control command value that is excessively increased is referred to as “maximum hysteresis”. That is, the maximum hysteresis is a change amount of the control command value required from E to F. This is a value obtained by subtracting the amount of control hysteresis from the amount of change in the control command value required to obtain a back pressure equal to the back pressure when the nozzle vane is operating toward the closing side.

  When the target value of the control command value of the actuator 56 is larger than G, the control command value does not need to be larger than the target value because it is not affected by hysteresis.

  In the present embodiment, it has been described that the total sum of play between each member is 5% of the control command value of the actuator 56. However, the total sum of play between each member is actually expressed as the control command value of the actuator 56. It is determined by experiment etc. what value is sometimes obtained. When the nozzle vane 73 is opened, the control command value of the actuator 56 is temporarily made larger than the target value by the maximum hysteresis (15%).

  In this embodiment, when the change amount of the control command value of the actuator 56 is smaller than the control hysteresis (5%), the control command value of the actuator 56 is adjusted to the target value without increasing it once. That is, the opening degree of the nozzle vane 73 is not once moved to the opening side from the target value.

  FIG. 4 is a time chart showing the transition of the control command value of the actuator 56. C, D, E, and F in FIG. 4 correspond to the symbols in FIG. Here, the alternate long and short dash line indicates the control hysteresis, and the broken line indicates the maximum hysteresis. When the control command value changes from D to E, the amount of change is larger than the control hysteresis, so the control command value is once set to F, which is once larger than the target value. Thereafter, the control command value is C. Note that E and C are equal in size.

  On the other hand, when the control command value changes from C to H, since the amount of change is smaller than the control hysteresis, the control command value is never once larger than the target value. That is, the control command value is not increased from H. Thereafter, when the target value of the control command value decreases to I, the control command value is directly decreased from D to I. In this embodiment, the ECU 10 that performs such control corresponds to the drive source control means in the present invention.

  In this way, it is possible to suppress the nozzle vane 73 from being opened more than necessary, and thus it is possible to suppress the supercharging pressure from decreasing.

  The maximum hysteresis in the first embodiment is not always constant. That is, when the play between the members increases due to secular change, or the size of the play changes due to expansion or contraction of each member due to temperature, the maximum hysteresis also changes. It can also vary depending on the operating state of the internal combustion engine. For example, when the maximum hysteresis of the nozzle vane 73 is smaller than expected, the nozzle vane 73 is opened more than necessary, so that the supercharging pressure may be lowered too much. Therefore, in this embodiment, the magnitude of the maximum hysteresis is corrected so that the supercharging pressure becomes the target value.

  FIG. 5 is a diagram showing the relationship between the control command value of the actuator 56 and the back pressure for each magnitude of hysteresis. A broken line indicates when the hysteresis is maximum, and a solid line indicates when the hysteresis is relatively small. This figure is before correction. Moreover, the case where the target opening degree of the nozzle vane 73 is 15% is shown. When the hysteresis is maximum, the locus is the same as in FIG. As the hysteresis decreases, the degree of the decrease in the back pressure with respect to the change in the control command value of the actuator 56 increases. Therefore, if the control command value of the actuator 56 is once 25% and then 15%, the locus becomes E ', F', B ', B, B', C. That is, when passing through F ′, B ′, B, B ′, and C, the back pressure becomes Y or less and falls more than necessary.

  Here, FIG. 6 is a diagram showing the supercharging pressure corresponding to FIG. The horizontal axis represents the control command value for the actuator 56. The alternate long and short dash line indicates when the hysteresis is maximum, and the solid line indicates when the hysteresis is relatively small. Each symbol corresponds to that in FIG. Thus, even if the target supercharging pressure is Y, since it once decreases to Z and then increases to Y, there is a time when the supercharging pressure decreases below the target value.

  On the other hand, the maximum hysteresis is corrected by the following equation.

  Maximum hysteresis after correction = (actual boost pressure / target boost pressure) x maximum hysteresis before correction

  The corrected maximum hysteresis obtained in this way is stored in the ECU 10 as a learned value, and this learned value is used as the maximum hysteresis during the next control of the nozzle vane 73. By doing in this way, a supercharging pressure can be maintained at a target value. In this embodiment, the ECU 10 that performs such control corresponds to the learning means in the present invention.

  Here, FIG. 7 is a graph showing the transition of the supercharging pressure when the maximum hysteresis is corrected based on the above formula. The horizontal axis represents the control command value for the actuator 56. The alternate long and short dash line indicates when the hysteresis is maximum, and the solid line indicates when the hysteresis is relatively small. Each symbol corresponds to that in FIG. As described above, when the hysteresis is relatively large, the control command value of the actuator 56 is lowered to 25%, but when the hysteresis is relatively small, it is lowered to 20% by correction. Thereby, since the supercharging pressure changes in the order of E ′, F ′, and C, the supercharging pressure can be maintained at the target value.

  In the present embodiment, when the internal combustion engine 1 becomes a predetermined medium load or more from a low load, the control command value of the actuator 56 is once made larger than the target value and set as the target value. This is done even if the target opening of the nozzle vane 73 is not changed.

  Here, assuming that the control hysteresis is 10%, for example, even if the target value of the control command value of the actuator 56 changes from 0% to 10%, the control command value of the actuator 56 is temporarily set lower than the target value (10%). It is decided to directly adjust to the target value (10%) without increasing it.

  In other words, when the control command value of the actuator 56 is 0% at low load and the target value changes to 10%, the control command value only changes to 10%. The pressure changes in the order of D and E.

  In other words, when the control command value of the actuator 56 is once made larger than the target value and then set to the target value, the back pressure becomes the magnitude of C (that is, Y), but the target is not increased once. If it is set to a value, the back pressure is the magnitude of E (ie, X).

  Here, at the time of low load, since the amount of exhaust gas is small, the back pressure is originally low, so the back pressure does not become excessively high even in the state of E in FIG. However, since the amount of exhaust increases at high loads, the back pressure may be excessively high in the E state.

  On the other hand, when the load becomes higher than a predetermined value, the target back pressure can be obtained by once increasing the control command value of the actuator 56 from the target value to the maximum hysteresis and then setting the target value. The load serving as the threshold at this time is obtained in advance by experiments or the like as a value that does not cause the back pressure to increase excessively. Thereby, the raise of a back pressure can be suppressed.

It is a figure which shows schematic structure of the internal combustion engine which concerns on an Example, and its intake / exhaust system. It is a block diagram of a turbocharger. FIG. 2A is a cross-sectional view showing a configuration of the turbocharger, and FIG. 2B is a view showing a variable nozzle mechanism of the turbocharger. It is the figure which showed the relationship between the control command value of an actuator, and a back pressure. It is a time chart which showed transition of a control command value of an actuator. It is the figure which showed the relationship between the control command value of an actuator and back pressure for every magnitude | size of hysteresis. It is the figure which showed the supercharging pressure corresponding to FIG. It is the figure which showed transition of the supercharging pressure at the time of correct | amending based on a hysteresis correction amount.

Explanation of symbols

1 Internal combustion engine 2 Cylinder 2A Intake port 2B Exhaust port 3 Intake passage 4 Exhaust passage 10 ECU
11 Pressure sensor 50 Variable displacement turbocharger 51 Compressor housing 52 Turbine housing 53 Center housing 54 Link chamber 55 Link rod 56 Actuator 60 Compressor 61 Turbine 62 Rotor shaft 63 Scroll chamber 70 Variable nozzle mechanism 71 Ring plate 72 Vane shaft 73 Nozzle vane 74 Vane arm 75 Drive ring 76 Clamping part 80 Link mechanism 81 Drive arm 82 Drive arm clamping part 83 Link shaft 84 Drive link 85 Pin 91 Guide

Claims (3)

In an internal combustion engine equipped with a variable displacement turbocharger that changes a flow rate of exhaust gas blown to a turbine by changing a nozzle vane angle so that a supercharging pressure becomes a desired pressure.
A drive source connected to the nozzle vane for driving the nozzle vane;
When the amount of change in the opening until the nozzle vane opening is increased to the target opening is less than a predetermined value, a command value corresponding to the opening corresponding to the target opening is given to the drive source, and the predetermined value or more Drive source control means for giving a command value corresponding to the target opening to the drive source after giving a command value corresponding to an opening larger than the target opening to the drive source,
An internal combustion engine with a supercharger. In an internal combustion engine equipped with a variable displacement turbocharger that changes a flow rate of exhaust gas blown to a turbine by changing a nozzle vane angle so that a supercharging pressure becomes a desired pressure.
A drive source connected to the nozzle vane for driving the nozzle vane;
When the opening degree of the nozzle vane is increased to the target opening degree, a command value corresponding to an opening degree larger than the target opening degree is given to the driving source, and then the command value corresponding to the target opening degree is used as the driving source. Drive source control means for providing,
A supercharging pressure measuring means for measuring the supercharging pressure;
The actual boost pressure when a command value corresponding to an opening larger than the target opening is given to the drive source is compared with the target boost pressure so that the actual pressure approaches the target pressure. Learning means for learning a command value corresponding to an opening larger than the target opening;
An internal combustion engine equipped with a supercharger.   When the load of the internal combustion engine has changed from a low load to a predetermined medium load or more, the drive source control means provides a command value corresponding to an opening larger than the current opening to the drive source and 2. The supercharged internal combustion engine according to claim 1, wherein a command value corresponding to the opening degree is given to the drive source.

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