JP4816514B2 - Internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to a supercharged internal combustion engine.

A technique is known in which an abnormality of a supercharger is determined by comparing a supercharging pressure detected by a supercharging pressure sensor with a predetermined supercharging pressure stored in advance (see, for example, Patent Document 1). .)
JP 2003-120304 A Japanese Patent Laid-Open No. 06-123234 Japanese Patent Laid-Open No. 06-346744 Japanese Patent Laid-Open No. 07-042567

  Here, in an internal combustion engine with a supercharger that is provided with two superchargers in parallel and the intake air merges downstream from the supercharger and then flows into the internal combustion engine, the supercharging capability of one of the superchargers is Even if it decreases, the supercharging pressure is compensated by the other supercharger. That is, when the supercharger is controlled based on the supercharging pressure downstream from the supercharger, the supercharging pressure is reduced when there is an abnormality in one supercharger and the supercharging pressure decreases. Both turbochargers are controlled to raise the. Actually, since the supercharging capability of one supercharger is lowered, the supercharging pressure is increased mainly by the other supercharger. In this way, the supercharging pressure is adjusted to the target value, but in this case, since the rotation speed of the other supercharger becomes higher than usual, there is a risk that the efficiency may be reduced or the life may be shortened.

  And even if there is an abnormality in one supercharger, if the supercharging pressure is compensated by the other supercharger, it becomes difficult to detect that there is an abnormality in one supercharger. For this reason, the other supercharger is used in an over-rotated state.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of detecting over-rotation of a supercharger in an internal combustion engine with a supercharger.

In order to achieve the above object, an internal combustion engine with a supercharger according to the present invention comprises:
One of intake air passing through the air flow meter is divided to flow into the plurality of superchargers provided in parallel, there a plurality of supercharged internal combustion engine in which the intake merge downstream of the supercharger provided in the parallel And
Pressure detection means for detecting the pressure of the intake air after the divided air intake upstream of the respective superchargers;
And a determination means the difference in pressure is abnormal in any of the supercharger is larger than the threshold value occurs which is detected by the pressure detecting means,
It is characterized by comprising.

The gas discharged from each supercharger merges and is then sucked into the internal combustion engine. Here, the pressure detection means compares the pressure of the intake air upstream of one supercharger with the pressure of the intake air upstream of the other supercharger. The term “upstream from the supercharger” here refers to a portion that is upstream for the supercharger but is not upstream for other superchargers. That is, when one intake passage is branched and connected to the supercharger, the area from the branch point to the supercharger corresponds to “upstream from the supercharger”.

The pressure between the branch of the intake passage and each supercharger is proportional to the velocity of the gas flowing into each supercharger. That is, this pressure is proportional to the flow rate of gas passing through each supercharger. Since there is a correlation between the flow rate of the gas passing through the supercharger and the rotation speed of the supercharger, the difference in pressure compared by the pressure detection means is correlated with the difference in rotation speed of the supercharger. is there. When the difference in the rotation speed of the supercharger increases, it is considered that any of the superchargers is overrotating.

  If the pressure difference when the difference in the rotation speed of the supercharger falls within the allowable range is set in advance as a threshold value, if any of the pressure differences exceeds the threshold value, any of the superchargers is abnormal. Can be determined to occur. By controlling the supercharger based on this determination, it is possible to suppress overspeed of the supercharger.

  The supercharger-equipped internal combustion engine according to the present invention can detect over-rotation of the 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 with a supercharger according to this embodiment. The internal combustion engine 1 is a V-type engine that includes a right bank 2 and a left bank 3. The right bank 2 and the left bank 3 are each provided with three cylinders.

  An intake manifold 4 is connected to the right bank 2 and the left bank 3. Intake air is distributed from the intake manifold 4 to the right bank 2 and the left bank 3. An intake passage 5 is connected to the intake manifold 4.

  The intake passage 5 is provided with a throttle 6 that adjusts the flow rate of intake air by adjusting the cross-sectional area of the intake passage 5. The intake passage 5 upstream of the throttle 6 is provided with an intercooler 7 that reduces the temperature of the intake air by exchanging heat between the intake air and the atmosphere. Further, the upstream intake passage 5 is provided with an air flow meter 8 for outputting a signal corresponding to the amount of air flowing through the intake passage 5.

  The intake passage 5 is divided into two parts, a right intake passage 21 and a left intake passage 31, between the air flow meter 8 and the intercooler 7.

  In the middle of the right intake passage 21, a compressor housing 22A of a right turbocharger 22 that operates using exhaust energy as a drive source is provided. On the other hand, a compressor housing 32A of a left turbocharger 32 that operates using exhaust energy as a drive source is provided in the middle of the left intake passage 31.

  A right exhaust manifold 23 is connected to the right bank 2. The right exhaust manifold 23 is connected to the turbine housing 22 </ b> B of the right turbocharger 22. The turbine housing 22B is connected to the right exhaust passage 24.

  A right bypass passage 25 that connects the upstream side and the downstream side of the turbine housing 22B is provided. In the middle of the right bypass passage 25, a right waste gate valve 26 for circulating or blocking exhaust gas is provided. By opening and closing the right waste gate valve 26, the amount of exhaust gas passing through the turbine housing 22B can be adjusted.

A left exhaust manifold 33 is connected to the left bank 3. The left exhaust manifold 33 is connected to the turbine housing 32B of the left turbocharger 32. The turbine housing 32B is connected to the left exhaust passage 34.

  A left bypass passage 35 that connects the upstream side and the downstream side of the turbine housing 32B is provided. In the middle of the left bypass passage 35, a left waste gate valve 36 for circulating or blocking exhaust gas is provided. By opening and closing the left waste gate valve 36, the amount of exhaust gas passing through the turbine housing 32B can be adjusted.

  In the middle of the right intake passage 21 upstream of the compressor housing 22A of the right turbocharger 22, a right pressure sensor 27 for measuring the pressure in the right intake passage 21 is attached. On the other hand, a left pressure sensor 37 for measuring the pressure in the left intake passage 31 is attached in the middle of the left intake passage 31 upstream of the compressor housing 32A of the left turbocharger 32. Further, a supercharging pressure sensor 9 for measuring the pressure in the intake manifold 4 is attached to the intake manifold 4.

  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 operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  In addition to the sensors described above, the ECU 10 is connected to a crank position sensor 11 for measuring the rotational speed of the internal combustion engine 1 and an atmospheric pressure sensor 12 for measuring the atmospheric pressure via electric wiring, and the output signals of these sensors are sent to the ECU 10. It is designed to be entered.

  On the other hand, the throttle 6, the right waste gate valve 26, and the left waste gate valve 36 are connected to the ECU 10 through electrical wiring, and the ECU 10 controls these devices.

  In the internal combustion engine 1 configured as described above, the air that has passed through the air flow meter 8 is divided into two and flows into the right turbocharger 22 or the left turbocharger 32. The air that has passed through the right turbocharger 22 or the left turbocharger 32 once merges and flows into the intake manifold 4. Thereafter, the intake air is distributed from the intake manifold 4 to the right bank 2 or the left bank 3.

  The ECU 10 opens and closes the right waste gate valve 26 and the left waste gate valve 36 so that the boost pressure obtained by the boost pressure sensor 9 becomes a target value. At this time, the right waste gate valve 26 and the left waste gate valve 36 are simultaneously opened and closed. The supercharging pressure is applied directly to the right waste gate valve 26 and the left waste gate valve 36, and when the predetermined supercharging pressure is reached, the right waste gate valve 26 and the left waste gate valve 36 are automatically opened. You may keep it.

  When the supercharging pressure is adjusted by simultaneously opening and closing the right waste gate valve 26 and the left waste gate valve 36 in this way, when the supercharging capability of one turbocharger is reduced, the other turbocharger is overrotated. May occur.

Here, FIG. 2 is a diagram showing a relationship among the turbo inflow air amount, the pressure ratio (P3 / P1), and the rotation rate of the turbocharger. The pressure ratio (P3 / P1) is such that the pressure P3 downstream of the compressor housing 22A of the right turbocharger 22 (ie supercharging pressure) P3 and the pressure upstream of the compressor housing 22A of the right turbocharger 22 (ie right pressure sensor 27). The pressure obtained by dividing by P1. That is, the pressure ratio (P3 / P1) is a value indicating how many times the pressure is increased when the intake air passes through the right turbocharger 22. Further, the turbocharger rotation rate NF is expressed as a ratio between the rotation speed at that time and the assumed maximum rotation speed, and becomes 1 at the assumed maximum rotation speed. When the turbocharger rotation rate NF is greater than 1, the turbocharger is over-rotating. The relationship in FIG. 2 can be obtained in advance by experiments or the like. The same relationship can be obtained for the left turbocharger 32.

  However, this relationship is based on the assumption that both the right turbocharger 22 and the left turbocharger 32 are normal, and this relationship does not hold if there is an abnormality in one of the turbochargers.

  Therefore, in this embodiment, the state of each turbocharger is determined based on the pressure obtained by the right pressure sensor 27 and the left pressure sensor 37.

Here, FIG. 3 is a diagram showing the relationship between the turbo upstream pressure and the turbo inflow air amount. Turbo upstream pressure, when the pressure of the upper stream of the compressor housing 22A of the right turbocharger 22 (i.e. the pressure obtained by the right pressure sensor 27) P1, and the atmospheric pressure P0, is represented by (P0-P1) / P0 The That is, the lower the pressure obtained by the right pressure sensor 27, the higher the turbo upstream pressure. The turbo inflow air amount is the amount of air that passes through the compressor housing 22A of the right turbocharger 22. This turbo inflow air amount is correlated with the rotational speed of the right turbocharger 22. The relationship shown in FIG. 3 is obtained in advance by experiments or the like and stored in the ECU 10.

  Then, the pressure obtained by the right pressure sensor 27 and the atmospheric pressure obtained by the atmospheric pressure sensor 12 are measured to calculate the turbo upstream pressure, and the turbo inflow air amount is obtained from this value and the relationship shown in FIG. be able to. For the left turbocharger 32, the turbo inflow air amount can be obtained in the same manner.

  When the absolute value of the difference between the turbo inflow air amount of the right turbocharger 22 and the turbo inflow air amount of the left turbocharger 32 is larger than a threshold value, it is determined that any turbocharger is over-rotating. . Note that the turbocharger over-rotation may be determined by directly comparing the pressure P1 obtained by the right pressure sensor 27 and the pressure P2 obtained by the left pressure sensor 37.

  Next, FIG. 4 is a flowchart showing a determination flow of the turbocharger overspeed in the present embodiment. This routine is repeatedly executed every predetermined time. In this flow, the pressure P1 obtained by the right pressure sensor 27 and the pressure P2 obtained by the left pressure sensor 37 are directly compared to detect over-rotation of the turbocharger.

  In step S101, the engine speed NE, the supercharging pressure P3, the pressure P1 obtained by the right pressure sensor 27, the pressure P2 obtained by the left pressure sensor 37, and the opening ATH of the throttle 6 are read. The engine speed NE is obtained by the crank position sensor 11. Further, the opening degree of the throttle 6 is obtained from a command value when the ECU 10 adjusts the opening degree of the throttle 6.

  In step S102, a supercharging pressure threshold value P3LIM is obtained based on the engine speed NE and the atmospheric pressure. The supercharging pressure threshold value P3LIM is determined in consideration of the durability of the internal combustion engine 1. The ECU 10 controls the right waste gate valve 26 and the left waste gate valve 36 so that the supercharging pressure P3 becomes equal to or less than the threshold value P3LIM.

In step S103, it is determined whether the supercharging pressure P3 is higher than a threshold value P3LIM. That is, it is determined whether or not the supercharging pressure P3 is excessively high due to a failure of the right waste gate valve 26 or the left waste gate valve 36.

  If an affirmative determination is made in step S103, the process proceeds to step S104. On the other hand, if a negative determination is made, the process proceeds to step S105.

  In step S104, it is determined that the turbocharger is in an overspeed state because there is an abnormality in the supercharging pressure control.

In step S105, the absolute value DP of the difference between the pressure P1 obtained by the right pressure sensor 27 and the pressure P2 obtained by the left pressure sensor 37 is calculated. In this embodiment, the ECU 10 that executes step S105 corresponds to the pressure detecting means in the present invention.

  In step S106, the threshold value DPLIM of the absolute value DP calculated in step S105 is calculated based on the engine speed NE and the opening ATH of the throttle 6. This threshold value DPLIM can be an upper limit value when the turbocharger is not over-rotating.

  In step S107, it is determined whether or not the value calculated in step S105 is larger than the threshold value DPLIM. That is, it is determined whether any turbocharger is over-rotating.

  If an affirmative determination is made in step S107, the process proceeds to step S108, whereas if a negative determination is made, this routine is temporarily terminated.

  In step S108, it is assumed that any one of the turbochargers is over-rotating. That is, in this embodiment, the ECU 10 that executes Step S107 and Step S108 corresponds to the determination means in the present invention.

  In step S109, in order to reduce the rotation speed of the turbocharger, the opening degree of the throttle 6 is moved to the closing side.

  In this way, it is possible to detect over-rotation of the turbocharger. When over-rotation of the turbocharger is detected, the over-rotation can be suppressed by operating the throttle 6 to reduce the rotation speed of the turbocharger.

  In this embodiment, the pressure upstream of the compressor housing of each turbocharger is measured and the pressure difference is calculated thereafter (step S105). Instead, the compressor housing of each turbocharger is calculated. Alternatively, the differential pressure upstream may be directly measured.

It is the figure which showed schematic structure of the internal combustion engine with a supercharger by an Example. It is the figure which showed the relationship between the amount of turbo inflow air, a pressure ratio (P3 / P1), and the rotation rate of a turbocharger. It is the figure which showed the relationship between turbo upstream pressure and turbo inflow air amount. It is the flowchart which showed the determination flow of the overcharge of the turbocharger in an Example.

Explanation of symbols

1 Internal combustion engine 2 Right bank 3 Left bank 4 Intake manifold 5 Intake passage 6 Throttle 7 Intercooler 8 Air flow meter 9 Supercharging pressure sensor 10 ECU
21 Right intake passage 22 Right turbocharger 22A Compressor housing 22B Turbine housing 23 Right exhaust manifold 24 Right exhaust passage 25 Right bypass passage 26 Right wastegate valve 27 Right pressure sensor 31 Left intake passage 32 Left turbocharger 32A Compressor housing 32B Turbine housing 33 Left exhaust manifold 34 Left exhaust passage 35 Left bypass passage 36 Left waste gate valve 37 Left pressure sensor

Claims (1)

One of intake air passing through the air flow meter is divided to flow into the plurality of superchargers provided in parallel, there a plurality of supercharged internal combustion engine in which the intake merge downstream of the supercharger provided in the parallel And
Pressure detection means for detecting the pressure of the intake air after the divided air intake upstream of the respective superchargers;
And a determination means the difference in pressure is abnormal in any of the supercharger is larger than the threshold value occurs which is detected by the pressure detecting means,
An internal combustion engine equipped with a supercharger.

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