JP2009270474A - Blow-by gas recirculation system - Google Patents

Abstract

The present invention efficiently separates oil contained in blow-by gas with a simple configuration.
Air pressurized by a compressor 11C of a supercharger 11 is supplied to an intake manifold 16 via an intercooler 14. The intake air is guided from the outlet of the intercooler 14 to the turbine inlet of the oil separation device 21 via the intake air extraction passage 22. The pressurized air exhausted from the turbine outlet of the oil separator 21 is returned to the upstream side of the compressor 11C. An impeller is connected to the turbine of the oil separator 21 via a turbine shaft. Blow-by gas is supplied to the impeller, and oil contained in the blow-by gas is separated by centrifugal force generated by the impeller. The blow-by gas that has undergone oil separation is guided to the turbine side of the oil separation device 21 through the hollow turbine shaft, and is returned to the upstream side of the compressor 11C together with the pressurized air.
[Selection] Figure 1

Description

  The present invention relates to a blow-by gas recirculation system including an oil separation device that separates oil contained in blow-by gas.

In a blow-by gas recirculation system provided in an internal combustion engine, blow-by gas (unburned gas) leaked into a crankcase or the like is recirculated to an intake system. The blow-by gas recirculated to the intake system is returned to the intake system via an oil separation device, and oil mist such as engine oil contained in the blow-by gas is separated and recovered from the blow-by gas. For oil separation, one using centrifugal separation is known, and various power sources are used as rotational power of the centrifugal separator. For example, a configuration in which blow-by gas is circulated into the oil separator, an impeller provided in the oil separator is rotated by the flow pressure of the blow-by gas, and oil having a large mass is separated and recovered by the centrifugal force of the impeller. It has been proposed (Patent Document 1).
JP 2005-113799 A

  However, in the configuration of Patent Document 1, since the rotation of the impeller depends on the flow rate of blow-by gas, the rotational force is insufficient, and oil separation may be insufficient depending on the operating state. Insufficient oil separation causes problems such as oil coking and increased oil consumption.

  An object of the present invention is to provide a blow-by gas recirculation system capable of efficiently separating oil with a simple configuration.

  The blow-by gas recirculation system of the present invention includes an impeller for separating oil from blow-by gas by a centrifugal action, and a turbine connected to the impeller, and the turbine is operated by air supplied from the downstream side of the intercooler, The air and blow-by gas discharged from the turbine are returned to the upstream side of the compressor of the supercharger.

  It is preferable that an intake air intake passage for flowing air from the intercooler downstream side to the turbine and a control valve provided in the intake air intake passage are provided, and the opening and closing of the control valve is controlled based on the compressor outlet temperature. Thereby, the operation of the turbine can be controlled in accordance with the operation state.

  The vane provided in the impeller preferably receives a fluid force from the blow-by gas and gives a rotational force to the impeller, and the impeller is rotated by the rotational force of the blow-by gas when the control valve is closed. Thereby, when the supercharging pressure is low, oil separation can be performed only by the fluid force of blow-by gas.

  The control valve is opened when the compressor outlet temperature is equal to or higher than a predetermined value. Thereby, when the supercharging pressure is high and the compressor outlet temperature is high, the turbine can be operated to enhance the oil separation action. Further, by extracting air from the downstream side of the intercooler, the temperature on the compressor inlet side can be lowered and the occurrence of oil coking can be suppressed.

  The control valve is opened when the throttle valve opening is operated in the closing direction. As a result, when the supercharging pressure increases instantaneously, such as during deceleration, the compressed air on the outlet side of the intercooler is recirculated to suppress the occurrence of compressor surge and to reduce noise caused by this. This can be prevented, and the oil separation efficiency at this time is enhanced.

  The impeller and the turbine are connected by a hollow turbine shaft, and a hole is provided on a side surface of the turbine shaft on the impeller side. Thereby, blow-by gas flows into the turbine shaft through the hole, and flows out from the open opening at the turbine side end of the turbine shaft to the turbine outlet. Thereby, blow-by gas and the air extracted from the intercooler downstream side can be efficiently recirculated using the same path.

  The impeller preferably includes a first disk coupled to the turbine shaft, a hollow blowby gas introduction shaft coaxial with the turbine shaft, and a second disk coupled to the blowby gas introduction shaft. The first and second disks are arranged in parallel, and the vanes are arranged radially between the first and second disks. The blow-by gas flows from the tip opening of the blow-by gas introduction shaft through the blow-by gas introduction shaft into the space between the first disk and the second disk, and radially flows in the radial direction by the first disk. Will be changed. Thereby, while being able to give centrifugal force to blowby gas by simple composition, an impeller can be rotated with the fluid force of blowby gas.

  Further, in order to efficiently obtain the rotational force of the impeller from blow-by gas and reduce the loss due to the vanes, it is preferable that the vanes have an arcuate curved surface shape.

  As described above, according to the present invention, it is possible to provide a blow-by gas recirculation system that can efficiently perform oil separation with a simple configuration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a blow-by gas recirculation system using an oil separation device according to an embodiment of the present invention.

  The blow-by gas recirculation system 10 is applied to a supercharged internal combustion engine 12 including a supercharger 11. That is, the air sucked from the air cleaner 13 is pressurized in the compressor 11C of the supercharger 11 and then supplied to the intake manifold 16 via the intercooler 14 and the throttle valve 15. In the present embodiment, the supercharger 11 is a turbocharger, and the exhaust from the exhaust manifold 17 is discharged to the outside through the turbine 11T and the exhaust catalyst 18 of the supercharger 11. Further, the internal combustion engine 12 includes an EGR system that communicates an intake manifold 16 and an exhaust manifold 17 and includes an EGR valve 19 and an EGR cooler 20. The supercharger 11 is not limited to a turbocharger, and may be any type of supercharger.

  An intake air intake passage 22 connected to the turbine inlet of the oil separator 21 is connected between the intercooler 14 and the throttle valve 15 in the intake passage. The upstream side of the compressor 11C is connected to the turbine outlet of the oil separator 21. The reflux path 23 to be connected is connected. Further, a control valve 24 is provided in the intake air extraction passage 22, and a temperature sensor 25 is provided in the vicinity of the outlet of the compressor 11C. The ECU 26 receives the compressor outlet temperature T detected by the temperature sensor 25, the opening degree of the throttle valve 15, and the like, and the opening / closing operation of the control valve 24 is controlled by the ECU 26 based on the compressor outlet temperature T and the throttle valve opening degree. Is done.

  FIG. 2 is a schematic cross-sectional view showing the configuration of the oil separation device 21. The oil separator 21 is a centrifugal oil separator and includes an impeller 27. The impeller 27 is connected to a turbine wheel 29 via a turbine shaft 28, and the turbine shaft 28 is rotatably held by a center housing 31 via a bearing 30.

  The turbine wheel 29 is accommodated in the turbine housing 32, and the intake air intake passage 22 is connected to a turbine inlet of a scroll 32 </ b> S provided in the turbine housing 32. Further, the turbine housing 32 is formed with a turbine outlet 32 </ b> A that opens in the axial direction of the turbine shaft 28, and the reflux passage 23 is connected thereto.

  The impeller 27 includes two disks 27A and 27B having substantially the same outer diameter arranged in parallel. A plurality of vanes 33 arranged radially are arranged between the disks 27A and 27B. The disk 27 </ b> A is coaxially connected to the turbine shaft 28, and the disk 27 </ b> B is connected to a blow-by gas introduction shaft 34 disposed coaxially with the turbine shaft 28. The outer peripheral portion of the impeller 27 is open, and the space between the disks 27A and 27B communicates with the outside.

  The impeller 27 is accommodated in an oil separation housing 35, and the oil separation housing 35 is formed with a circular opening 35A into which the blow-by gas introduction shaft 34 is inserted. A blowby gas passage 36 having an inner diameter larger than the outer diameter of the blowby gas introduction shaft 34 is connected to the opening 35A. The blow-by gas passage 36 is a passage connected to a crankcase or the like of the internal combustion engine 12, and the blow-by gas is supplied to the oil separation device 21 through the blow-by gas passage 36.

  For example, a lip seal 37 is interposed between the outer peripheral surface of the blowby gas introduction shaft 34 that extends into the blowby gas passage 36 through the opening 35 </ b> A of the oil separation housing 35 and the inner peripheral surface of the blowby gas passage 36. . The blow-by gas introduction shaft 34 is rotatably held with respect to the blow-by gas passage 36 and the oil separation housing 35 via a lip seal 37.

  Further, the outer peripheral portion 35B of the oil separation housing 35 is, for example, an inclined surface, and a drain passage 38 communicating with the oil pan of the internal combustion engine 12 is connected to the lower side of the hollow portion. The shape of the outer peripheral portion 35B may be any shape as long as the oil separated and attached to the wall surface of the outer peripheral portion 35B flows into the drain passage 38.

  The blow-by gas introduction shaft 34 is a hollow shaft, and a base end portion thereof is connected to an opening portion 27C provided at the center of the disk 27B. The tip of the blow-by gas introduction shaft 34 opens in the passage axial direction in the blow-by gas passage 36. Therefore, the blow-by gas supplied from the blow-by gas passage 36 passes through the shaft from the tip opening of the blow-by gas introduction shaft 34 to the space (inside the impeller 27) defined by the disks 27A and 27B in the axial direction. Inflow along.

  The turbine shaft 28 is also configured as a hollow shaft, and the end of the turbine shaft 28 on the disk 27A side is closed by the disk 27A. One or more holes 28A communicating with the interior of the turbine shaft 28 are formed in the side wall of the turbine shaft 28 disposed in the oil separation housing 35 in the vicinity of the disk 27A. The other end of the turbine shaft 28 is inserted through the turbine wheel 29 and opened toward the turbine outlet 32A.

  FIG. 3 is a plan view showing the arrangement of the vanes 33 in the disk 27A (27B). The vane 33 extends from a predetermined position outside the opening 27C of the disk 27B to the outer periphery of the disk 27A (27B), and its surface is disposed perpendicular to the disks 27A and 27B. The vane 33 is formed, for example, as an arcuate curved surface, and the camber line of the vane 33 is disposed, for example, along the radial direction at the front edge portion. The camber line of the vane 33 gradually warps in the direction opposite to the rotational direction A of the impeller 27 toward the rear edge.

  Next, the oil separation operation of the oil separation device 21 and the control operation of the control valve 24 provided in the intake air extraction passage 22 will be described.

  The control valve 24 is a valve that controls the flow of pressurized air supplied from the downstream side of the intercooler 14 to the turbine of the oil separator 21. When the output of the internal combustion engine 12 increases, the supercharging pressure increases, so the outlet temperature T of the compressor 11C also increases, and at the same time the amount of blow-by gas increases. Under such conditions, oil is likely to remain in the blow-by gas, and oil coking may occur in the outlet passage of the compressor 11C, thereby reducing the compressor efficiency.

  Therefore, under such conditions, it is necessary to increase the rotation of the impeller 27 in order to increase the efficiency of oil separation. In this embodiment, the temperature sensor 25 is used to monitor the outlet temperature of the compressor 11 </ b> C, the control valve 24 is opened when the compressor outlet temperature is equal to or higher than the predetermined value T <b> 1, and the impeller 27 is driven by the turbine provided in the oil separator 21. Rotate at high speed.

  When the compressor outlet temperature T is lower than the predetermined value T1 and the control valve 24 is closed, the impeller 27 is rotated by the fluid force of blow-by gas. That is, the blowby gas supplied through the blowby gas passage 36 is introduced into the impeller 27 in the axial direction via the blowby gas introduction shaft 34. The blow-by gas that has flowed into the impeller 27 collides with the wall surface of the disk 27A orthogonal to the axial direction, changes the flow in the radial direction, and radially reaches the wall surface 35B of the oil separation housing 35 from the outer periphery of the impeller 27. It flows out towards.

  At this time, the vane 33 gains lift by the blow-by gas flowing out, the impeller 27 is rotated in the direction A in FIG. 3, and the oil contained in the blow-by gas is caused by centrifugal action due to the rotation of the impeller 27 It adheres to the wall surface 35B of the oil separation housing 35.

  Further, since the control valve 24 is opened when the compressor outlet temperature T is equal to or higher than the predetermined value T1, the turbine wheel 29 of the oil separator 21 is pressurized by the compressor 11C of the supercharger 11 via the intake air extraction passage 22. Then, pressurized air cooled in the intercooler 14 is supplied. Thereby, the turbine wheel 29 is rotated at a higher speed than when the control valve 24 is closed, and the impeller 27 connected to the turbine wheel 29 via the turbine shaft 28 is rotated at a high speed. That is, oil with a large mass adheres to the wall surface 35 </ b> B by the centrifugal action of the impeller 27. The oil adhering to the wall surface 35B reaches the drain passage 38 along the wall surface 35B and is collected into the oil pan.

  On the other hand, the blow-by gas from which the oil has been separated flows into the turbine shaft 28 through a hole 28A provided in the turbine shaft 28 and passes through an opening 28B of the turbine shaft 28 provided on the turbine wheel 29 side. It is discharged to the reflux passage 23. The blow-by gas that has flowed out into the circulation passage 23 is returned to the upstream side (negative pressure side) of the compressor 11C of the supercharger 11 through the reflux passage 23, and when the control valve 24 is open, the blow-by gas is pressurized. It is recirculated to the upstream side (negative pressure side) of the compressor 11C together with the air.

  Further, when the throttle is returned (when the throttle valve 15 is operated in the closing direction), the outlet pressure of the intercooler 14 increases instantaneously. Such a sudden increase in the supercharging pressure may cause a compressor surge and generate noise. Therefore, in this embodiment, apart from the determination based on the compressor outlet temperature T, when the throttle valve 15 is operated in the closing direction such as during deceleration, the control valve 24 is opened and the outlet pressure of the intercooler 14 is set to the oil separator 21. And returning this to the upstream side of the compressor 11C, it is possible to suppress the occurrence of compressor surge and prevent the occurrence of noise.

  FIG. 4 shows a flowchart of the opening / closing operation process of the control valve 24 described above. The control valve opening / closing operation process is repeatedly executed in the ECU 26 at a predetermined timing.

  In step S100, it is determined whether or not the throttle valve opening has been operated in the closing direction. If the throttle valve opening is not operated in the closing direction, it is determined in step S102 whether the compressor outlet temperature T is equal to or higher than a predetermined value T1. If it is determined in step S100 that the throttle valve opening has been operated in the closing direction, or if it is determined in step S102 that the compressor outlet temperature T is equal to or higher than the predetermined value T1, the control valve 24 is turned on in step S104. The valve is opened, and the control valve opening / closing operation process ends. On the other hand, if it is determined in step S102 that the compressor outlet temperature T is lower than the predetermined value T1, the control valve 24 is closed or maintained in the closed state in step S106, and this control valve opening / closing operation processing is performed. Ends.

  As described above, according to the present embodiment, oil contained in blow-by gas can be more efficiently separated in various operating states with a simple configuration. That is, since the rotational power of the impeller 27 uses the energy of blow-by gas or the intercooler outlet pressure, the loss is small compared to the case where power is transmitted from the engine camshaft or the case where an electric motor is used. The configuration is also simple. Note that even if the pressurized air is extracted from the intercooler outlet, the operation performance of the internal combustion engine is hardly affected.

  Further, when the control valve 24 is opened, the temperature of the air that has been lowered by the intercooler is further lowered in the turbine of the oil separation device 21, so that the temperature of the air and the blow-by gas that is recirculated to the inlet side of the compressor 11C And the temperature on the outlet side of the compressor 11C decreases accordingly. Thereby, the suppression effect of oil coking is further enhanced.

  Further, in the present embodiment, since the control valve 24 is opened even when the throttle is returned, the generation of noise due to the compressor surge can be prevented, and in such a case, the oil separation efficiency can be further improved.

  In this embodiment, the vane has an arcuate curved surface, but a flat plate may be used for the vane and the vane may be arranged at a predetermined angle with respect to the radial direction of the impeller.

  In this embodiment, the control valve is kept closed until the compressor outlet temperature reaches a predetermined value, and the valve is opened when the compressor outlet temperature exceeds the predetermined value. It is good also as a structure to increase. For example, in a predetermined temperature range, it is possible to start opening the control valve from the lower limit value and to set the maximum opening at the upper limit value.

It is a block diagram which shows the structure of the blowby gas recirculation system using the oil separation apparatus which is one Embodiment of this invention. It is typical sectional drawing which shows the structure of a blowby gas recirculation | reflux system. It is a top view which shows arrangement | positioning of the vane provided in the impeller. It is a flowchart of the process which opens and closes a control valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Blow-by gas recirculation system 11 Supercharger 11C Supercharger compressor 12 Internal combustion engine 14 Intercooler 15 Throttle valve 21 Oil separator 22 Intake take-out passage 23 Recirculation passage 24 Control valve 25 Temperature sensor 26 ECU
27 impeller 28 turbine shaft 28A hole 28B opening 29 turbine wheel (turbine)
33 Vane 34 Blow-by gas introduction shaft 35 Oil separation housing 36 Blow-by gas passage 38 Drain passage

Claims (9)

An impeller for separating oil from blow-by gas by centrifugal action;
A turbine connected to the impeller,
The turbine is operated by air supplied from the downstream side of the intercooler, and the air discharged from the turbine and the blowby gas are returned to the upstream side of the compressor of the supercharger. system.   An intake air intake passage through which air flows from the downstream side of the intercooler to the turbine, and a control valve provided in the intake air intake passage, and the opening and closing of the control valve is controlled based on a compressor outlet temperature. The blow-by gas recirculation system according to claim 1.   The blow-by gas recirculation system according to claim 2, wherein a vane provided in the impeller receives a fluid force from the blow-by gas and gives a rotational force to the impeller.   The blow-by gas recirculation system according to claim 3, wherein the impeller is rotated by a rotational force of the blow-by gas when the control valve is closed.   The blow-by gas recirculation system according to claim 4, wherein the control valve is opened when the compressor outlet temperature is equal to or higher than a predetermined value.   The blow-by gas recirculation system according to any one of claims 1 to 5, wherein the control valve is opened when a throttle valve opening degree is operated in a closing direction.   A hollow turbine shaft that connects the impeller and the turbine is provided, a hole is provided on a side surface of the turbine shaft on the impeller side, and the blow-by gas flows into the turbine shaft through the hole, The blow-by gas recirculation system according to any one of claims 1 to 6, wherein the blow-by gas recirculation system flows out from an open opening at a turbine side end of the turbine shaft to the turbine outlet.   The impeller includes a first disk coupled to the turbine shaft, a hollow blowby gas introduction shaft coaxial with the turbine shaft, and a second disk coupled to the blowby gas introduction shaft; The first and second disks are arranged in parallel, the vanes are arranged radially between the first and second disks, and the blow-by gas flows from the tip opening of the blow-by gas introduction shaft to the blow-by gas. The air flows into the space between the first disk and the second disk through the introduction shaft, and the flow is radially changed by the first disk in a radial direction. The blow-by gas recirculation system according to claim 3.   The blowby gas recirculation system according to claim 9, wherein the vane has an arcuate curved surface shape.