JP4661536B2 - Turbocharger control device - Google Patents

Description

  The present invention relates to a turbocharger control device, and more particularly to a turbocharger control device suitable as a device for controlling a vehicular turbocharger having a variable diffuser.

  Conventionally, for example, Patent Document 1 discloses a method for controlling a supercharger (turbocharger) having means for varying a supercharging pressure such as a variable diffuser. This conventional control method includes a rotation angle of a variable diffuser ring, the number of rotations of a supercharger, a pressure and temperature at a blower outlet (compressor outlet), a differential pressure between a blower spiral chamber outer peripheral wall pressure and an inner peripheral wall pressure, and The rotational angle of the variable diffuser or the like is controlled based on the outer peripheral wall pressure, the exhaust gas inlet temperature, the rotational speed of the diesel engine, and the fuel flow rate.

JP-A-61-205330

  As described above, the conventional control method controls a variable diffuser or the like using a number of control parameters. For this reason, the control logic becomes complicated and the stability of the control is not good. Moreover, since it will be necessary to provide many sensors, cost will increase.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a turbocharger control device that is low in cost and excellent in control stability without requiring a special sensor. To do.

In order to achieve the above object, a first invention is a turbocharger control device having a variable diffuser in a compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
Equipped with a,
When the target diffuser vane opening is a value on the closing side, the target opening setting means is configured so that the opening difference between adjacent stages is smaller than when the opening is a value on the opening side. It characterized that you set the diffuser vane opening.
In order to achieve the above object, a second invention is a turbocharger control device having a variable diffuser in a compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
With
In the case where the relationship information is set based on the relationship between the engine speed and the supercharging pressure,
The relationship information is characterized in that a value at which the target diffuser vane opening is constant is set so that the supercharging pressure increases as the engine speed increases.
In order to achieve the above object, a third invention is a turbocharger control device having a variable diffuser in a compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
With
In the case where the relationship information is set based on the relationship with the engine speed, the relationship information indicates the target diffuser vane opening based on the supercharging pressure when the load of the internal combustion engine becomes the maximum load. Is set.
In order to achieve the above object, a fourth invention is a turbocharger control device having a variable diffuser in a compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
With
In the case where the relationship information is set based on the relationship with the engine speed,
The relationship information is characterized in that the target diffuser vane opening is set larger when the internal combustion engine is in transition than when it is steady.

In a fifth aspect based on the first aspect , the relationship information is set based on a relationship between the engine speed and the supercharging pressure.
The relationship information is characterized in that a value at which the target diffuser vane opening is constant is set so that the supercharging pressure increases as the engine speed increases.

In a sixth aspect based on the first aspect , in the case where the relationship information is set based on a relationship with the engine speed, the relationship information indicates that the load of the internal combustion engine is a maximum load. The target diffuser vane opening is set with reference to the supercharging pressure.

According to a seventh aspect of the present invention, in the first, third, or sixth aspect , the relationship information is set based on a relationship with the engine speed.
The relationship information is characterized in that the target diffuser vane opening is set larger when the internal combustion engine is in transition than when it is steady.

According to the first aspect of the present invention, it is possible to realize a low-cost system with excellent control stability while avoiding a surge without requiring a special sensor. When the opening of the diffuser vane becomes a value on the closing side, the surge limit region and the region with high turbo efficiency are close to each other. According to the present invention, in a region where the opening degree of the diffuser vane is a value on the closing side, the target diffuser vane opening degree is finely controlled, so that the turbo efficiency can be kept high while avoiding a surge.
According to the second aspect of the present invention, it is possible to realize a low cost and excellent control stability system while avoiding a surge without requiring a special sensor. Further, according to the present invention, the diffuser vane opening degree can be controlled so that the operating range of the turbocharger is always within the surge limit range.
According to the third aspect of the present invention, it is possible to realize a low cost and excellent control stability system while avoiding a surge without requiring a special sensor. Further, according to the present invention, when the target diffuser vane opening is set based only on the engine speed without using the supercharging pressure, it is possible to completely avoid the surge.
According to the fourth aspect of the present invention, it is possible to realize a low cost and excellent control stability system while avoiding a surge without requiring a special sensor. When the internal combustion engine is in a transient state, the flow rate of air passing through the compressor of the turbocharger is larger than when it is in a steady state. As a result, the surge limit is less likely to be exceeded during transients than during steady state. According to the present invention, it is possible to operate the turbocharger in a region where the turbo efficiency is high by increasing the target diffuser vane opening at the time of transition compared to the steady state.

According to the fifth aspect of the invention, the diffuser vane opening degree can be controlled so that the operating range of the turbocharger is always within the surge limit range.

According to the sixth aspect of the present invention, when the target diffuser vane opening degree is set based only on the engine speed without using the supercharging pressure, the surge can be completely avoided.

When the internal combustion engine is in a transient state, the flow rate of air passing through the compressor of the turbocharger is larger than when it is in a steady state. As a result, the surge limit is less likely to be exceeded during transients than during steady state. According to the seventh aspect , the turbocharger can be operated in a region where the turbo efficiency is high by increasing the target diffuser vane opening at the time of transition compared to the steady state.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a diagram for explaining a schematic configuration of an internal combustion engine including a turbocharger with a variable diffuser according to Embodiment 1 of the present invention. The system shown in FIG. 1 controls the operation of the diesel engine 10 having a plurality of cylinders, an intake system that supplies air to the diesel engine 10, an exhaust system that discharges exhaust gas from the diesel engine 10, and the diesel engine 10. And a control system.

The intake system of the diesel engine 10 includes an intake manifold 12 and an intake pipe 14 connected to the intake manifold 12. Air is taken into the intake pipe 14 from the atmosphere and distributed to the combustion chambers of the respective cylinders via the intake manifold 12. The intake manifold 12 is provided with a supercharging pressure (intake pressure) sensor 16 that outputs a signal corresponding to the pressure in the intake manifold 12.
The system shown in FIG. 1 includes a turbocharger 18 with a variable diffuser. A compressor housing 20 of the turbocharger 18 with a variable diffuser is provided in the middle of the intake pipe 14.

  The exhaust system of the diesel engine 10 includes an exhaust manifold 22 and an exhaust pipe 24 connected to the exhaust manifold 22. The exhaust gas discharged from each cylinder of the diesel engine 10 is collected in the exhaust manifold 22 and is discharged to the exhaust pipe 24 via the exhaust manifold 22. In the middle of the exhaust pipe 24, the turbine housing 26 of the turbocharger 18 with a variable diffuser described above is provided.

  The control system of the diesel engine 10 includes an ECU (Electronic Control Unit) 28. In addition to the supercharging pressure sensor 16 described above, the ECU 28 includes a crank angle sensor 30 for detecting the engine speed Ne, an atmospheric pressure sensor 32 for detecting atmospheric pressure, and an atmospheric temperature for detecting atmospheric temperature. Various sensors such as the sensor 34 are connected. The ECU 28 is connected to various actuators such as an actuator (not shown) for opening and closing a diffuser vane 46 (see FIG. 2) of the turbocharger 18 with a variable diffuser. The ECU 28 drives each actuator according to a predetermined control program based on the output of each sensor. In FIG. 1, P0 represents the atmospheric pressure P0 of the air taken into the intake pipe 14, and P3 represents the compressor outlet pressure (supercharging pressure) P3 of the turbocharger 18 with a variable diffuser.

Next, the detailed structure of the turbocharger 18 with a variable diffuser will be described with reference to FIGS.
FIG. 2 is a cross-sectional view for explaining the overall configuration of the turbocharger 18 with a variable diffuser shown in FIG. In addition, the arrow attached | subjected in FIG. 2 has shown the flow direction of the air which passes an intake system, or the exhaust gas which passes an exhaust system.

  As shown in FIG. 2, a turbine wheel 36 that is rotationally driven by exhaust energy of exhaust gas discharged to the exhaust pipe 24 is disposed in the turbine housing 26. A compressor impeller 40 that is integrally connected to the turbine wheel 36 by a connecting shaft 38 is disposed in the compressor housing 20. The connecting shaft 38 is rotatably supported by a center housing 42 represented in a simplified manner in FIG. A variable diffuser 44 is disposed downstream of the compressor impeller 40 in the air passage in the compressor housing 20.

  FIG. 3 is a diagram for explaining the configuration of the compressor unit in which the variable diffuser 44 is incorporated. More specifically, FIG. 3A is a view of the compressor impeller 40 as viewed from the direction indicated by the arrow A in FIG. 2, and FIG. 3B is a view of the compressor impeller 40 in FIG. It is the figure seen from the back side with respect to A). As shown in FIG. 3A, a plurality of diffuser vanes 46 of the variable diffuser 44 are arranged on the outer periphery of the compressor impeller 40. Each diffuser vane 46 is rotatably attached to a donut-like base plate 48 fixed to the compressor housing 20 via a rotation shaft 50. The rotation shaft 50 is arranged concentrically with the compressor impeller 40 at equal angular intervals.

  As shown in FIG. 3B, the variable diffuser 44 has a configuration for changing the openings of the plurality of diffuser vanes 46 all at once. A unison ring 52 having a plurality of semicircular cutouts 52a on the inner peripheral side is disposed on the back surface of the base plate 48 (the surface viewed from the direction shown in FIG. 3B). Further, one end of the driven arm 54 is fixed to the rotating shaft 50 of the diffuser vane 46 on the back surface of the base plate 48.

  The other end of the driven arm 54 is formed in a circular shape and is engaged with the notch 52 a of the unison ring 52. The inner periphery of the unison ring 52 is guided by a plurality of guide rollers 56 attached to the back side of the base plate 48 so that the unison ring 52 can be rotated while being concentric with the base plate 48.

  On the back surface of the base plate 48, a rotation shaft 58 different from the rotation shaft 50 is rotatably attached. One end of the drive arm 60 is fixed to the rotating shaft 58. The other end of the drive arm 60 is formed in a circular shape, like the driven arm 54, and is engaged with the notch 52 a of the unison ring 52. The variable diffuser 44 includes a link mechanism 62 for driving the drive arm 60 to rotate. One end of the link mechanism 62 is fixed to the rotating shaft 58, and the other end is connected to the actuator (not shown) described above.

  According to the above configuration, when the ECU 28 gives a drive command to the actuator, the link mechanism 62 is driven in the direction of the arrow shown in FIG. The movement of the link mechanism 62 is converted into the rotational movement of the drive arm 60. When the drive arm 60 rotates, the unison ring 52 is rotated in the direction of the arrow in FIG. Then, the rotational movement of the unison ring 52 is transmitted through the driven arm 54, whereby the opening degrees of all the diffuser vanes 46 are changed at the same time. As described above, according to the configuration described above, the opening degree of the diffuser vane 46 can be adjusted to an arbitrary opening degree based on the drive command of the ECU 28.

[Description of operating characteristics of turbocharger with variable diffuser]
FIG. 4 is a diagram showing the relationship between the pressure ratio P3 / P0, which is the ratio between the atmospheric pressure P0 and the compressor outlet pressure P3, and the air flow rate Ga-nom. In FIG. 4A, a waveform indicated by a broken line indicates a line where the engine speed Ne is constant, and a waveform indicated by a thick line indicates a line indicating a surge limit. A waveform indicated by a thin line indicates a line where the turbo rotational speed is constant (particularly, a limit line of the turbo rotational speed in FIG. 4A). Moreover, the waveform shown with a dashed-dotted line has shown the full (at the time of maximum load) operating line of the diesel engine 10 determined by a smoke limit, exhaust temperature, etc. FIG. In the following description, the opening degree of the diffuser vane 46 may be abbreviated as “VGC opening degree”.

  In each opening degree of the diffuser vane 46 shown in FIG. 4A, the region on the right side of the surge line corresponds to a region where the turbocharger 18 can be operated stably without being affected by the surge. However, if the air flow rate Ga-nom is increased while the VGC opening is kept constant, the air flow rate Ga-nom will eventually reach the choke flow rate (limit flow rate). On the other hand, the region on the left side of the surge line corresponds to a region where the operation of the turbocharger 18 becomes unstable due to the influence of the surge. According to the tendency shown in FIG. 4A, even if the engine speed Ne is constant, if the pressure ratio P3 / P0 increases, the surge limit is reached and the operation of the turbocharger 18 becomes unstable. It becomes easy.

  FIG. 4B shows the change in turbo efficiency (the obtained supercharging pressure / the work applied to the turbocharger) with respect to the change in the VGC opening. That is, a closed curve surrounded by a broken line in FIG. 4B indicates an efficiency contour line of the turbocharger 18, and a closed curve with a smaller area indicates a region with higher turbo efficiency. As can be seen from FIG. 4B, in the turbocharger 18 with a variable diffuser, the region where the turbo efficiency is high varies depending on the VGC opening, and the VGC on the opening side changes when the VGC opening is on the closing side. Compared with the opening degree, the region with high turbo efficiency becomes narrower.

  More specifically, as shown in FIG. 4B, in the region where the VGC opening is on the closing side, the region with high turbo efficiency is limited to the vicinity of the line indicating the surge limit. Therefore, it is necessary to control the target VGC opening with high accuracy so that it is close to the surge line and does not exceed the surge limit in a small region of the air flow rate Ga-nom where the VGC opening tends to be close. In the region where the VGC opening is on the open side, the highest efficiency point of turbo efficiency is on the side where the air flow rate Ga-nom is slightly larger than the surge line. Therefore, unless the relative relationship with the surge line is changed in accordance with the target VGC opening, it is not possible to perform turbo-efficient operation.

  Therefore, in the system according to the present embodiment, the turbocharger 18 with the variable diffuser having the operation characteristics described with reference to FIG. 4 can obtain a good turbo efficiency while reliably avoiding a surge with a low-cost configuration. The purpose is to control the VGC opening. Specifically, the target VGC opening degree is set based on the engine speed Ne and the supercharging pressure P3 by the routine method shown in FIG.

[Specific Processing in Embodiment 1]
FIG. 5 is a flowchart of a routine executed by the ECU 28 in order to set the target VGC opening based on the engine speed Ne and the boost pressure P3 in the first embodiment. Note that this routine is periodically executed at predetermined time intervals. In the routine shown in FIG. 5, first, the engine speed Ne and the intake manifold (intake manifold) pressure Pb are read based on the outputs of the crank angle sensor 30 and the supercharging pressure sensor 16, respectively (step 100). Here, in order to obtain information on the supercharging pressure (compressor outlet pressure) P3 used in the following steps, the supercharging pressure sensor 16 that is generally provided in the diesel engine 10 is used to supercharge. Although the intake manifold pressure Pb having a certain relationship with the pressure P3 is acquired, the present invention is not limited to this, and the compressor outlet pressure P3 may be directly acquired by providing a pressure sensor at the compressor outlet.

  Next, the target VGC opening is determined based on the engine speed Ne and the intake manifold pressure Pb by referring to the data map shown in FIG. 6 (step 102). More specifically, the value between each map value is obtained by interpolating two neighboring map values when referring to this data map. For this reason, the target VGC opening is continuously determined. FIG. 6 is a map in which the target VGC opening degree is determined in relation to the engine speed Ne and the supercharging pressure P3 (intake manifold pressure Pb). In FIG. 6, straight lines indicated by thin lines indicate lines where the VGC opening is constant, and waveforms indicated by thick lines indicate full (maximum load) operating lines of the diesel engine 10.

In the map shown in FIG. 6, a value at which the VGC opening is constant is set so that the boost pressure P3 increases as the engine speed Ne increases, in other words, a straight line that rises to the right in FIG. 6. ing. Further, in the map shown in FIG. 6, in the region where the target VGC opening is on the closing side, the opening adjustment of the target VGC is made finer than the region where the target VGC opening is on the opening side. In other words, the value of the target VGC opening is stored so that the opening difference between adjacent stages becomes smaller. In order to explain this conceptually, in FIG. 6, the number of straight lines in which the target VGC opening is constant on the closing side is increased.
Next, a VGC drive signal is output from the ECU 28 to the actuator of the variable diffuser 44 based on the target VGC opening determined in step 102 (step 104).

  Even if the engine speed Ne is the same, the higher the pressure ratio P3 / P0, the easier the operating region of the turbocharger 18 enters the unstable region due to surge (see FIG. 4). In such a case, it is necessary to control the VGC opening to the closed side in order to avoid an unstable region exceeding the surge limit. In the map shown in FIG. 6 described above, the value at which the VGC opening is constant is set so that the supercharging pressure P3 becomes higher as the engine speed Ne becomes higher, in other words, a straight line rising to the right in FIG. Is set. According to such a setting, when considering the case where the engine speed Ne is constant and the boost pressure P3 is high, the target VGC opening degree becomes a close side value as the boost pressure P3 increases. Can be set. That is, according to the setting of the map shown in FIG. 6, the VGC opening degree can be controlled so that the operating range of the turbocharger 18 is always within the surge limit range.

  Further, controlling the VGC opening degree to the closed side has an effect of preventing a surge that occurs in a region where the air flow rate Ga-nom is small. However, as described with reference to FIG. 5 above, in the region where the VGC opening is on the closing side, the region with high turbo efficiency is limited to a region close to the surge line and narrow. As a result, if the air flow rate Ga-nom is increased while maintaining the VGC opening on the closed side, the turbo efficiency will deteriorate rapidly, and eventually the choke flow rate will be reached. Can only increase slightly. For this reason, it is necessary to control the target VGC opening to the open side.

  According to the routine shown in FIG. 5 using the map shown in FIG. 6, the target VGC opening degree on the closing side is finely adjusted as compared with the opening side. That is, in the region where the VGC opening is on the closing side, the target VGC opening is adjusted more frequently with respect to the change in the air flow rate Ga-nom. As a result, the VGC opening degree can be controlled so that a turbo-efficient operating region near the surge line is maintained. Thereby, it is possible to achieve both avoidance of surge and high turbo efficiency.

  As described above, according to the system of the present embodiment, the target VGC opening degree is controlled based on the engine speed Ne and the supercharging pressure P3 (intake manifold pressure Pb), and thus an internal combustion engine having a general configuration. The variable diffuser uses a turbo-efficient area while avoiding surges in a low-cost, stable system, with no need for additional special sensors and simple control logic The attached turbocharger 18 can be controlled.

  By the way, in the first embodiment described above, the target VGC opening corresponding to the engine speed Ne and the supercharging pressure P3 is acquired according to the relationship defined in the target VGC opening acquisition map shown in FIG. However, the relationship information in the present invention is not limited to such a map. For example, the relation information may be a relational expression that defines a relation of the target VGC opening degree with respect to the engine speed Ne and the boost pressure P3.

  Further, in the first embodiment described above, the target VGC opening is set according to a map defined by the relationship between the engine speed Ne and the supercharging pressure P3. The method shown with reference to FIGS. 7 and 8 may be used. FIG. 7 is a flowchart of a routine executed by the ECU 28 in place of the routine shown in FIG. 5 in order to realize the control by such a method. In the routine shown in FIG. 7, first, in addition to the engine speed Ne and the intake manifold pressure Pb, the atmospheric pressure P0 and the atmospheric temperature Ta are acquired based on the output of each sensor (step 200).

Next, correction values for the engine speed Ne and the intake manifold pressure Pb are calculated (step 202). Specifically, the correction value of the engine speed Ne is calculated as Ne · (Ta) ^1/2 / P0, and the correction value of the intake manifold pressure (supercharging pressure) Pb is calculated as Pb / P0. Next, with reference to the data map shown in FIG. 8, the target VGC opening is determined based on the relationship between the correction value of the engine speed Ne and the correction value of the intake manifold pressure (supercharging pressure) Pb (step 204). . The map shown in FIG. 8 is set in the same manner as the map shown in FIG. 6 except that the engine speed Ne and the intake manifold pressure Pb (supercharging pressure P3) are replaced with respective correction values.

Next, a VGC drive signal is output from the ECU 28 to the actuator of the variable diffuser 44 based on the target VGC opening acquired in step 204 (step 206).
According to the routine shown in FIG. 7 described above, the turbocharger 18 with a variable diffuser is controlled with higher accuracy than the routine shown in FIG. 5 by adding correction based on the atmospheric pressure P0 and the atmospheric temperature Ta. be able to.

In the first embodiment described above, the map shown in FIG. 6 that the ECU 28 refers to when executing step 102 corresponds to the “related information” in the first to fourth inventions. Further, when the ECU 28 executes the process of step 102, the “target opening degree setting means” in the first to fourth inventions executes the process of step 104, so that the first to fourth steps are performed. The “opening degree command means” in the invention is realized respectively.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG. 9 and FIG.
The system of the present embodiment can be realized by causing the ECU 28 to execute a routine shown in FIG. 9 described later instead of the routine shown in FIG. 5 using the hardware configuration shown in FIGS. is there. In the configuration shown in FIG. 1, the supercharging pressure sensor 16 is provided to acquire the pressure Pb (supercharging pressure P3) in the intake manifold 12, but in terms of realizing the system of this embodiment. Need not include the supercharging pressure sensor 16.

[Features of Embodiment 2]
In the system of the first embodiment described above, the target VGC opening is determined based on the engine speed Ne and the boost pressure P3. On the other hand, the system of the present embodiment is variable by using a system configuration that is lower in cost than the system of the first embodiment by determining the target VGC opening degree based only on the engine speed Ne. The turbocharger 18 with a diffuser is controlled.

[Specific Processing in Second Embodiment]
FIG. 9 is a flowchart of a routine executed by the ECU 28 in the second embodiment to realize the above function. Note that this routine is periodically executed at predetermined time intervals. In the routine shown in FIG. 9, first, the engine speed Ne is read (step 300). Next, the engine speed increase rate Ne / dt is calculated (step 302).

  Next, a predetermined reference value (Ne / dt) 0 of the engine rotation rate Ne / dt is referred to (step 304). The reference value (Ne / dt) 0 is a threshold value for determining whether the operation state of the diesel engine 10 is in a steady state or a transient state. Next, it is determined whether or not the engine speed increase rate Ne / dt is equal to or less than a reference value (Ne / dt) 0 (step 306).

  When it is determined in step 306 that the engine rotation rate Ne / dt ≦ reference value (Ne / dt) 0 is satisfied, that is, when it can be determined that the current operating state of the diesel engine 10 is in a steady state. The target VGC opening degree is determined based on the engine speed Ne by referring to the map value at the steady state in the data map shown in FIG. 10 (step 308).

  FIG. 10 is a map in which the target VGC opening is determined in relation to the engine speed Ne. In FIG. 10, the waveform indicated by the solid line indicates the tendency of the map value at the steady state. The target VGC opening in the map shown in FIG. 10 is set with reference to the value of the supercharging pressure P3 when the load of the diesel engine 10 becomes the maximum load at each engine speed Ne. In other words, the map shown in FIG. 10 defines the target VGC opening on the full operating line of the diesel engine 10 in the map shown in FIG. 6 in relation to the engine speed Ne. According to this map setting, the target VGC opening is set to the most closed value at each engine speed Ne, so the surge limit is exceeded at any engine speed Ne. Thus, the target VGC opening at each engine speed Ne can be controlled. For this reason, even in a system that does not include the supercharging pressure sensor 16, the turbocharger 18 can be operated in a state in which a surge is always avoided regardless of the operation region of the diesel engine 10.

  Further, in the map shown in FIG. 10, the target VGC opening is changed to a larger opening side value with respect to the increase in the engine speed Ne in the low engine speed region than in the high engine speed region. Is set to According to such a setting, in a small air flow rate region where the engine speed Ne is low, that is, a region where the VGC opening is on the closing side, the target VGC opening is more frequently caused by a change in the air flow Ga-nom. Will be adjusted. As a result, the VGC opening degree can be controlled so that a turbo-efficient operating region near the surge line is maintained. Thereby, it is possible to achieve both avoidance of surge and high turbo efficiency.

  On the other hand, if it is determined in step 306 that the engine rotation rate Ne / dt ≦ reference value (Ne / dt) 0 is not satisfied, that is, it is determined that the current operating state of the diesel engine 10 is in a transient state. If possible, the target VGC opening is determined based on the engine speed Ne by referring to the map value at the time of transition in the data map shown in FIG. 10 (step 310). That is, in the map shown in FIG. 10, the setting of the target VGC opening at the time of transition is different from the setting of the target VGC opening at the time of steady state.

  More specifically, the target VGC opening at the time of transition is set to be larger than the target VGC opening at the time of steady state. At the time of transition, it is necessary to fill the intake pipe 14 downstream of the compressor in addition to a delay in the increase in the turbo rotational speed. For this reason, when the engine speed Ne is the same, the air flow rate Ga-nom passing through the compressor is larger at the time of transition than at the steady state. As a result, the surge limit is less likely to be exceeded during transients than during steady state. According to the setting of the map shown in FIG. 10, the turbocharger 18 can be operated in a region where turbo efficiency is high by increasing the target VGC opening at the time of transition as compared with the steady state.

  In the routine shown in FIG. 9, a VGC drive signal is then output from the ECU 28 to the actuator of the variable diffuser 44 based on the target VGC opening determined in the above step 308 or 310 (step 312).

  According to the routine shown in FIG. 9 described above, it is possible to realize a system with good turbo efficiency while completely avoiding a surge by using a system configuration that is cheaper than that of the first embodiment. In addition, by simplifying the control, it is possible to realize a system that can reduce the number of man-hours to be adapted and is excellent in robustness.

It is a figure for demonstrating schematic structure of an internal combustion engine provided with the turbocharger with a variable diffuser in Embodiment 1 of this invention. It is sectional drawing for demonstrating the whole structure of the turbocharger with a variable diffuser shown in FIG. It is a figure for demonstrating the structure of the compressor part in which the variable diffuser was incorporated. It is a figure which shows the relationship between pressure ratio P3 / P0 which is ratio of atmospheric pressure P0 and compressor outlet pressure P3, and air flow rate Ga-nom. It is a flowchart of the routine performed in Embodiment 1 of the present invention. 6 is a target VGC opening degree acquisition map referred to in the routine shown in FIG. It is a flowchart of the routine performed in the modification of Embodiment 1 of this invention. FIG. 8 is a target VGC opening degree acquisition map referred to in the routine shown in FIG. 7. FIG. It is a flowchart of the routine performed in Embodiment 2 of this invention. 10 is a target VGC opening degree acquisition map referred to in the routine shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diesel engine 12 Intake manifold 14 Intake pipe 16 Supercharging pressure sensor 18 Turbocharger 20 with a variable diffuser Compressor housing 24 Exhaust pipe 26 Turbine housing 28 ECU (Electronic Control Unit)
30 Crank angle sensor 40 Compressor impeller 44 Variable diffuser 46 Diffuser vane 48 Base plate 52 Unison ring 54 Drive arm 60 Drive arm 62 Link mechanism

Claims (7)

A turbocharger control device having a variable diffuser in the compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
Equipped with a,
When the target diffuser vane opening is a value on the closing side, the target opening setting means is configured so that the opening difference between adjacent stages is smaller than when the opening is a value on the opening side. control device for a turbocharger, characterized in that you set the diffuser vane opening. A turbocharger control device having a variable diffuser in the compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
Equipped with a,
In the case where the relationship information is set based on the relationship between the engine speed and the supercharging pressure,
The relationship information, the so said supercharging pressure as the engine rotational speed is high increases, the control device of the turbocharger, wherein the target diffuser vane opening is characterized that you have set the value becomes constant. A turbocharger control device having a variable diffuser in the compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
Equipped with a,
In the case where the relationship information is set based on the relationship with the engine speed, the relationship information indicates the target diffuser vane opening based on the supercharging pressure when the load of the internal combustion engine becomes the maximum load. turbocharger control device, characterized that you have to set the. A turbocharger control device having a variable diffuser in the compressor section,
It has relationship information that defines the target diffuser vane opening of the variable diffuser based on at least the relationship between the engine speed and the supercharging pressure, and within a range that does not exceed the surge limit according to the relationship information. Target opening setting means for setting the target diffuser vane opening;
Opening command means for instructing the variable diffuser to control according to the target diffuser vane opening set by the target opening setting means;
Equipped with a,
In the case where the relationship information is set based on the relationship with the engine speed,
The relationship information, the transient time of the internal combustion engine, turbocharger control device, characterized that you have set large the target diffuser vane opening than during steady. In the case where the relationship information is set based on the relationship between the engine speed and the supercharging pressure,
The relationship information, the so said supercharging pressure as the engine rotational speed is high increases, turbocharger according to claim 1, wherein said target diffuser vane opening is characterized in that it sets the value to be a constant Control device. In the case where the relationship information is set based on the relationship with the engine speed, the relationship information is based on the boost pressure when the load of the internal combustion engine becomes the maximum load, and the target diffuser vane opening degree The turbocharger control device according to claim 1, wherein: In the case where the relationship information is set based on the relationship with the engine speed,
The relationship information, the transient time of the internal combustion engine, turbocharger control apparatus according to claim 1, 3 or 6, wherein a is set larger the target diffuser vane opening than during steady.

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