JP2011236811A - Internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease perturbation of intake when an EGR gas is supplied to a diffuser part of a turbocharger.SOLUTION: An internal combustion engine with a supercharger having a diffuser wing 62 in the diffuser part of a compressor housing includes the EGR device for having an EGR passage connecting an exhaust passage of the internal combustion engine to an air intake passage and supplying part of exhaust as the EGR gas. Part 313 of the EGR passage is formed on the diffuser wing 62, and the EGR passage 313 formed in the diffuser wing 62 is opened downstream in a direction of the flow of the air intake in a diffuser wing surface.

Description

  The present invention relates to an internal combustion engine provided with a supercharger.

  A technique for supplying EGR gas from a diffuser part (compressor impeller outlet part) of a turbocharger is known (see, for example, Patent Document 1). Since the pressure in the diffuser portion of the turbocharger is relatively low, EGR gas can be easily introduced by supplying EGR gas from this location. For this reason, an operation for reducing the throttle opening, for example, for facilitating the introduction of EGR gas is not required, so that the pump loss can be reduced.

  However, by introducing EGR gas into the diffuser part, the flow of intake air in the diffuser part may be disturbed, and the static pressure recovery effect by the diffuser may be reduced. And if static pressure recovery effect falls, compressor efficiency will fall.

JP 05-071427 A JP 2007-255220 A JP 2009-270472 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce disturbance in the flow of intake air when supplying EGR gas to the diffuser portion of the turbocharger.

In order to achieve the above object, an internal combustion engine equipped with a supercharger according to the present invention includes:
In an internal combustion engine including a supercharger having a diffuser blade in a diffuser portion of a compressor housing,
An EGR device that has an EGR passage connecting the exhaust passage and the intake passage of the internal combustion engine and supplies a part of the exhaust gas as EGR gas to the intake passage;
A part of the EGR passage is formed in the diffuser blade;
The EGR passage formed in the diffuser blade is characterized by opening toward the downstream side in the intake air flow direction on the diffuser blade surface.

  That is, the EGR gas taken in from the exhaust passage is supplied from the diffuser blade into the intake passage after flowing through the EGR passage. Since the EGR passage opens toward the downstream side in the flow direction of the intake air, the EGR gas supplied into the intake passage flows along the diffuser blade surface, thereby suppressing disturbance of the intake air flow. be able to. Thereby, since the static pressure recovery effect in a diffuser part becomes larger, it can suppress that compressor efficiency falls. Note that the diffuser blades may be fixed in angle or changeable in angle. Further, the EGR passage that opens to the diffuser blades only needs to face the downstream side rather than the right angle with respect to the flow direction of the exhaust gas. Further, the outlet of the EGR passage formed in the diffuser blade may be provided on the downstream side in the intake air flow direction.

  In the present invention, the EGR passage formed in the diffuser blade may be opened on the front end side rather than the rear end side of the diffuser blade.

  The front end side with respect to the rear end side of the diffuser blade is, for example, the upstream side when it is divided into the upstream side and the downstream side from the center of the length of the diffuser blade in the flow direction of the intake air. That is, it may be upstream of the center of the diffuser blade. Here, since the pressure near the outlet of the compressor impeller is lower than the pressure near the outlet of the diffuser section, the EGR passage opens on the front end side of the diffuser blade, so that the EGR passage opens at a low pressure portion. become. As a result, it is possible to easily supply the EGR gas, and it is not necessary to perform an operation such as closing the throttle in order to increase the EGR gas amount, so that the pump loss can be further reduced.

  In the present invention, the EGR passage formed in the diffuser blade may open to the diffuser blade surface on the compressor impeller side.

  By supplying EGR gas from the diffuser blade surface on the compressor impeller side (the surface of the diffuser blade that faces the compressor impeller side), the EGR gas can be supplied from a place where the static pressure is lower. As a result, it is possible to easily supply the EGR gas, and it is not necessary to perform an operation such as closing the throttle in order to increase the EGR gas amount, so that the pump loss can be further reduced.

  ADVANTAGE OF THE INVENTION According to this invention, disturbance of the flow of intake air when supplying EGR gas to the diffuser part of a turbocharger can be reduced.

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 sectional drawing when a compressor housing is cut | disconnected in the center axis direction. It is sectional drawing when cut | disconnecting by the cutting line BB shown in FIG. FIG. 4 is an enlarged view of a portion indicated by C in FIG. 3. It is the flowchart which showed the supply flow of EGR gas which concerns on an Example.

  Hereinafter, a specific embodiment of an internal combustion engine provided with a supercharger according to the present invention will be described based on the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 1 and its intake / exhaust system according to this embodiment. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine having four cylinders 2. Note that this embodiment can be applied to other engines such as a gasoline engine.

  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 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.

  A compressor impeller 54 having a plurality of blades is provided in the compressor housing 51, and a turbine impeller 55 having a plurality of blades is provided in the turbine housing 52. The compressor impeller 54 and the turbine impeller 55 are connected via a rotor shaft 56.

  Further, the internal combustion engine 1 includes a diffuser blade EGR device 30 that recirculates a part of the exhaust gas flowing in the exhaust passage 4 to the intake passage 3 in the compressor housing 51. The diffuser blade EGR device 30 includes an external EGR passage 31, a first EGR valve 32, a first EGR cooler 33, and a filter 34.

  The external EGR passage 31 connects the exhaust passage 4 upstream of the turbine housing 52 and the compressor housing 51. An EGR gas passage is also formed in the compressor housing 51, and this structure will be described later. The external EGR passage 31 is provided with a first EGR valve 32, a first EGR cooler 33, and a filter 34 in order from the intake passage 3 side.

  The first EGR valve 32 adjusts the amount of EGR gas flowing through the external EGR passage 31 by changing the passage cross-sectional area of the external EGR passage 31. The first EGR cooler 33 exchanges heat between the EGR gas passing through the first EGR cooler 33 and the cooling water of the internal combustion engine 1 to lower the temperature of the EGR gas. The filter 34 collects PM and foreign matter in the EGR gas. Further, a differential pressure sensor 35 that detects a pressure difference between the upstream side and the downstream side of the filter 34 is attached to the external EGR passage 31. The differential pressure sensor 35 detects clogging of the filter 34.

  The internal combustion engine 1 is also provided with a second EGR device 40 that recirculates part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3. The second EGR device 40 includes a second EGR passage 41, a second EGR valve 42, and a second EGR cooler 43.

  The second EGR passage 41 connects the exhaust passage 4 upstream of the turbine housing 52 and the intake passage 3 downstream of the compressor housing 51.

  Further, the second EGR valve 42 adjusts the amount of EGR gas flowing through the second EGR passage 41 by changing the passage sectional area of the second EGR passage 41. Further, the second EGR cooler 43 exchanges heat between the EGR gas passing through the second EGR cooler 43 and the cooling water of the internal combustion engine 1 to lower the temperature of the EGR gas.

  Next, the turbocharger 50 will be described. FIG. 2 is a cross-sectional view of the compressor housing 51 cut along the central axis A direction. FIG. 3 is a cross-sectional view taken along the cutting line BB shown in FIG. Further, FIG. 4 is an enlarged view of a portion indicated by C in FIG. In FIG. 2, A indicates the central axis (rotation center) of the compressor impeller 54, the turbine impeller 55, and the rotor shaft 56.

A diffuser portion 61 is provided immediately downstream of the compressor impeller 54. In the diffuser portion 61, a plurality of diffuser blades 62 are arranged at equal angles with the central axis A as the center and the blade surface toward the compressor impeller 54. The diffuser blades 62 may be fixed to the compressor housing 51, and the angle may be changed by an actuator or the like. When the angle of the diffuser blade 62 can be changed, the diffuser blade 62 rotates about the rotation shaft 63. A well-known technique can be used for these structures.

  In the compressor housing 51, an in-housing EGR passage 311 serving as an EGR gas passage is formed (see FIG. 2). In addition, an in-blade EGR passage 312 and an opening 313 are formed inside the diffuser blade 62 as an EGR gas passage (see FIG. 4). One end of the in-housing EGR passage 311 is connected to the external EGR passage 31, and the other end of the in-housing EGR passage 311 is connected to the in-blade EGR passage 312. Further, the in-blade EGR passage 312 is connected to the opening 313, and the opening 313 opens at the diffuser blade surface 621.

  The in-blade EGR passage 312 is formed such that its central axis is parallel to the central axis A of the compressor impeller 54. The opening 313 opens on the diffuser blade surface 621 on the central axis A side of the diffuser blade 62 on the front end side (may be near the front end) of the diffuser blade 62 and is downstream in the intake air flow direction (diffuser). It opens toward the rear end side of the wing 62 (in the direction of the arrows in FIGS. 3 and 4). The opening 313 is formed in parallel with the bottom surface 611 of the diffuser portion 61. If the angle of the diffuser blade 62 can be changed, for example, the blade EGR passage 312 is formed in the rotation shaft 63 using the rotation shaft 63 as a hollow tube. Then, a hole is formed in the rotating shaft 63 in order to connect the in-blade EGR passage 312 and the opening 313. When the angle of the diffuser blade 62 is fixed, for example, an in-blade EGR passage 312 is formed by making a hole in the diffuser blade 62 parallel to the central axis A on an extension line of the in-housing EGR passage 311. Then, an opening 313 is formed by making a hole from the diffuser blade surface 621 toward the in-blade EGR passage 312.

  The in-housing EGR passage 311, the in-blade EGR passage 312, and the opening 313 are part of the diffuser in-blade EGR device 30. The EGR gas flows in the order of the external EGR passage 31, the in-housing EGR passage 311, the in-blade EGR passage 312, and the opening 313, and is introduced from the exhaust passage 4 to the intake passage 3. In this embodiment, the external EGR passage 31, the in-housing EGR passage 311, the in-blade EGR passage 312 and the opening 313 correspond to the EGR passage in the present invention.

  Here, the pressure at the outlet of the compressor impeller 54 (that is, the pressure between the compressor impeller 54 and the diffuser blade 62) is higher than the pressure at the outlet of the diffuser portion 61 (that is, the pressure downstream of the diffuser blade 62). Low. For this reason, the opening 313 that opens on the surface of the diffuser blade 62 on the central axis A side and on the front end side (may be near the front end) of the diffuser blade 62 opens at a location where the static pressure is relatively low. Will be. As a result, the difference between the pressure on the exhaust passage 4 side and the pressure on the intake passage 3 side of the EGR device 30 in the diffuser blade is increased, so that EGR gas is easily introduced. Then, in order to supply EGR gas, for example, it is not necessary to close the throttle and lower the intake pressure, so that the pump loss can be reduced.

  In addition, since the opening 313 opens toward the downstream side in the exhaust flow direction (that is, the rear end side of the diffuser blade 62), the EGR gas can flow along the surface of the diffuser blade 62. Disturbances in the flow of intake air can be suppressed. Thereby, the fall of compressor efficiency can be suppressed.

Here, if the in-housing EGR passage 311 is opened at right angles to the diffuser portion 61 without providing the in-blade EGR passage 312 and the opening 313, the turbulence of the intake air flow in the diffuser portion 61 becomes large, and the diffuser 61 The static pressure recovery effect in the part 61 is reduced.
Thereby, there exists a possibility that compressor efficiency may fall. On the other hand, according to the diffuser blade EGR device 30 according to the present embodiment, the disturbance of the flow of the intake air when the EGR gas is supplied can be suppressed, so that the reduction in the static pressure recovery effect can be suppressed.

  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 controls the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the request of the driver.

  A first EGR valve 32 and a second EGR valve 42 are connected to the ECU 10 via electrical wiring, and the first EGR valve 32 and the second EGR valve 42 are controlled by the ECU 10. Further, the output signal of the differential pressure sensor 35 is input to the ECU 10.

  The ECU 10 mainly supplies EGR gas from the diffuser blade EGR device 30. For example, when the filter 34 is clogged or the diffuser blade EGR device 30 fails, the EGR gas is supplied from the second EGR device 40.

  FIG. 5 is a flowchart showing an EGR gas supply flow according to this embodiment. This routine is executed every predetermined time by the ECU 10.

  In step S101, it is determined whether or not the differential pressure dP obtained by the differential pressure sensor 35 is smaller than a predetermined value dPCRI. In this step, it is determined whether or not the filter 34 is clogged. That is, the predetermined value dPCRI is a lower limit value of the differential pressure when clogging occurs. In this step, it may be determined whether or not the diffuser blade EGR device 30 is normal. If an affirmative determination is made in step S101, the process proceeds to step S102, and if a negative determination is made, the process proceeds to step S103.

  In step S102, the second EGR valve 42 is fully closed, the first EGR valve 32 is opened, and EGR gas is supplied from the diffuser blade EGR device 30. For example, the relationship between the engine speed and the engine load and the opening degree of the first EGR valve 32 is obtained in advance through experiments or the like and mapped, and the opening degree of the first EGR valve 32 is determined based on the map. Further, the opening degree of the first EGR valve 32 may be feedback controlled based on the intake air amount.

  In step S103, the first EGR valve 32 is fully closed, the EGR 42 is opened, and EGR gas is supplied from the second EGR device 40. That is, the filter 34 is clogged, and the supply of EGR gas from the diffuser blade EGR device 30 cannot be expected. Therefore, the EGR gas is supplied from the second EGR device 40. For example, the relationship between the engine speed and the engine load and the opening degree of the second EGR valve 42 is obtained in advance through experiments or the like and mapped, and the opening degree of the second EGR valve 42 is determined based on the map. Further, the opening degree of the second EGR valve 42 may be feedback controlled based on the intake air amount.

  Thus, until the filter 34 is clogged, the pump loss can be reduced by supplying the EGR gas only from the EGR device 30 in the diffuser blade. Even if the filter 34 is clogged, EGR gas can be supplied from the second EGR device 40 instead.

1 Internal combustion engine 2 Cylinder 3 Intake passage 4 Exhaust passage 10 ECU
30 EGR device 31 in diffuser blade 31 EGR passage 32 First EGR valve 33 First EGR cooler 34 Filter 35 Differential pressure sensor 40 Second EGR device 41 Second EGR passage 42 Second EGR valve 43 Second EGR cooler 50 Turbocharger 51 Compressor housing 52 Turbine housing 53 Center Housing 54 Compressor impeller 55 Turbine impeller 56 Rotor shaft 61 Diffuser portion 62 Diffuser blade 63 Rotating shaft 310 External EGR passage 311 EGR passage 311 in housing EGR passage 313 in blade 611 Opening 611 Bottom surface 621 of diffuser portion

Claims (3)

In an internal combustion engine including a supercharger having a diffuser blade in a diffuser portion of a compressor housing,
An EGR device that has an EGR passage connecting the exhaust passage and the intake passage of the internal combustion engine and supplies a part of the exhaust gas as EGR gas to the intake passage;
A part of the EGR passage is formed in the diffuser blade;
An internal combustion engine having a supercharger, wherein an EGR passage formed in the diffuser blade opens toward a downstream side in a flow direction of intake air on a diffuser blade surface.   2. The internal combustion engine with a supercharger according to claim 1, wherein the EGR passage formed in the diffuser blade opens at a front end side rather than a rear end side of the diffuser blade.   The internal combustion engine having a supercharger according to claim 1 or 2, wherein an EGR passage formed in the diffuser blade opens to a diffuser blade surface on a compressor impeller side.

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