JP7192256B2 - Blow-by gas system for supercharged engines - Google Patents

Description

The present invention relates to a blow-by gas system for a supercharged engine.

Patent Literature 1 below describes a configuration in which a blow-by gas introduction portion is connected to a branch portion of a supercharger bypass passage in an intake device for an engine with a mechanical supercharger.

Generally, a mechanical supercharger includes a pair of supercharger rotors rotatably arranged inside a supercharger main body via a plurality of bearings.

JP-A-04-203213

In the above Patent Document 1, EGR (Exhaust Gas Recirculation) gas is introduced into the intake passage on the upstream side of the turbocharger, and dust such as soot and condensed water due to the EGR gas However, there is a risk of adversely affecting the plurality of bearings and the seals disposed adjacent thereto. Therefore, it is important to ensure the lubricity and sealing performance of each bearing portion and each seal material.

The present invention solves the above-mentioned conventional problems, and is capable of improving the lubricating property of the bearing portion and seal material of the supercharging rotor by oil mist and preventing the entry of dust, condensed water, etc. into the bearing portion. intended to

In order to achieve the above object, the present invention provides a plurality of links branched from a portion downstream of a PCV valve in a blow-by gas passage and connected to spaces provided in the vicinity of bearings of a supercharger main body. A passage is provided.

Specifically, the present invention is aimed at a blow-by gas system for a supercharged engine, and has taken the following solutions.

That is, a first invention provides a driven supercharger having a supercharger rotor rotatably disposed in a working chamber of a supercharger body via a suction-side bearing and a discharge-side bearing, and an intake path. A bypass passage that branches off from the downstream portion of the throttle valve, bypasses the driven supercharger and is connected to the intake manifold, has a bypass valve that opens when not supercharged, and blow-by gas discharged from the crankcase of the engine. , a blow-by gas passage introduced through a PCV valve to a downstream portion of a throttle valve in an intake passage, and a blow-by gas device for a turbocharged engine, wherein the turbocharger main body is located near each bearing portion. The blow-by gas passage is provided with a first communication passage and a second communication passage branched from a portion downstream of the PCV valve in the blow-by gas passage and connected to the respective spaces. It is

According to this, one end is connected to the blow-by gas passage connected to the downstream portion of the throttle valve in the intake passage, and the other end is provided in the vicinity of each bearing on the intake side and the discharge side of the supercharger main body. By providing two communication passages connected to the space, a pressure difference is generated between the working chamber by the supercharging rotor and each space. Therefore, in each space, this pressure difference causes an inflow of blow-by gas or an action of ventilation. As a result, the lubricating properties of the bearings of the supercharging rotor due to the oil mist are improved, and the entry of dust and condensed water into the bearings can be prevented.

A second invention is based on the first invention, wherein the introduction passage to the intake passage in the blow-by gas passage and the branch passages of the first communication passage and the second communication passage branched from the introduction passage are provided in the bypass passage. It may be formed integrally with the main body including the bypass valve.

According to this, since the introduction passage of the blow-by gas passage to the intake passage and the branch passages of the two communication passages branched from the introduction passage are integrally formed in the body portion of the bypass passage, the blow-by gas passage and the , the layout with each communication path can be configured organically and compactly.

In a third aspect based on the second aspect, the first communication passage and the second communication passage are oriented in the direction of the row of cylinders of the engine and arranged above the supercharger main body and the supercharger main body. It may be arranged through between the pipe portion excluding the body portion of the bypass passage.

According to this, the gas flows smoothly in each communicating path, and the layout of each communicating path can be made compact.

In a fourth aspect of the invention, in the first to third aspects of the invention, the supercharging rotor is composed of two supercharging rotors, and the space near each bearing on the suction side of the two supercharging rotors is defined by each bearing. The annular spaces are formed adjacent to sealing materials arranged in the vicinity of the respective annular spaces, and each annular space may be connected by a single first connection path extending from the first communication path.

According to this, it is possible to connect each annular space and the first communication path with a simple configuration in which a single first connection path is formed in the turbocharger main body.

According to a fifth aspect of the present invention, in any one of the first to third aspects, the supercharging rotor is composed of two supercharging rotors, and the space near each bearing portion on the discharge side of the two supercharging rotors is defined by each bearing portion. is an annular space formed between the double sealing materials respectively arranged in the vicinity of each of the annular spaces, and each annular space may be connected by a second connection path and connected to the second communication path .

According to this, each annular space on the discharge side can be connected to the second communication passage with a simple configuration.

According to the present invention, it is possible to improve the lubricating property of the bearing portion and the sealing material of the supercharging rotor by the oil mist, and to prevent dust, condensed water, and the like from entering the bearing portion.

FIG. 1 is a schematic configuration diagram showing an engine according to one embodiment of the present invention. FIG. 2 is a front view showing essential parts of an intake path in the engine according to one embodiment of the present invention. FIG. 3 is a plan view showing the main part of the intake path in the engine according to one embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing the flow of intake air during supercharging in the intake path of the engine according to one embodiment of the present invention. FIG. 5 is a schematic configuration diagram showing the flow of intake air during natural intake in the intake path of the engine according to one embodiment of the present invention. FIG. 6 is a cross-sectional view along the rotational axis direction, a right cross-sectional view taken along line VIa-VIa, and a left cross-sectional view taken along line VIb-VIb, showing a supercharger arranged in an intake path of an engine according to an embodiment of the present invention. is. FIG. 7 is a rear view showing essential parts of an intake path in the engine according to one embodiment of the present invention. FIG. 8 is a plan view showing a supercharger arranged in an intake path of an engine according to one embodiment of the present invention. FIG. 9 is a schematic configuration diagram showing connection between a turbocharger and a blow-by gas reduction system in an engine according to one embodiment of the present invention. 10 is a partial cross-sectional view showing an enlarged region A of FIG. 9. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or its uses.

(one embodiment)
An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the configuration of a drive-type supercharged engine according to the present embodiment, here, a mechanical supercharged engine (hereinafter simply referred to as "engine") 1. there is FIG. 2 is a front view of the engine 1, and FIG. 3 is a top view of the engine 1. As shown in FIG. In addition, in FIGS. 2 and 3 and subsequent drawings, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

The engine 1 is, for example, a four-stroke internal combustion engine mounted on an automobile, and includes a mechanical supercharger 34, as shown in FIGS. The fuel for the engine 1 is not particularly limited, but is gasoline in this embodiment.

Further, although not shown in detail, the engine 1 includes four cylinders (cylinders) 11 arranged in a row, and the four cylinders 11 are mounted so as to line up along the vehicle width direction. It is configured as a so-called in-line four-cylinder horizontal engine. Thus, in this configuration example, the longitudinal direction of the engine, which is the direction in which the four cylinders 11 are arranged (cylinder row direction), substantially coincides with the vehicle width direction, and the engine width direction substantially coincides with the vehicle longitudinal direction. I am doing it.

In an in-line multi-cylinder engine, the direction of the row of cylinders coincides with the direction of the central axis of the crankshaft 15 as the engine output shaft (the direction of the engine output shaft). In the following description, these directions may be collectively referred to as cylinder row direction (or vehicle width direction).

Hereinafter, unless otherwise specified, the front side refers to the front side in the longitudinal direction of the vehicle, the rear side refers to the rear side in the longitudinal direction of the vehicle, and the left side refers to one side in the vehicle width direction (one side in the cylinder row direction). The right side indicates the other side in the vehicle width direction (the other side in the cylinder row direction, the engine front side).

Further, in the following description, the upper side refers to the upper side in the vehicle height direction when the engine 1 is mounted on the vehicle (hereinafter also referred to as the "vehicle mounted state"), and the lower side refers to the vehicle height direction when the engine 1 is mounted in the vehicle. pointing to the bottom of the

(Schematic configuration of the engine)
In this embodiment, the engine 1 is of a front intake/rear exhaust type. That is, the engine 1 includes an engine body 10 having four cylinders 11, an intake path 30 disposed on the front side of the engine body 10 and communicating with each cylinder 11 through an intake port 18, and a rear side of the engine body 10. and an exhaust passage 50 communicating with each cylinder 11 via the exhaust port 19 .

In this configuration example, the intake path 30 includes a plurality of passages for guiding intake air, devices such as a supercharger 34 and an intercooler 36, and an air bypass passage (hereinafter simply referred to as (referred to as a "bypass passage") 40 constitutes a unitized intake system.

The engine body 10 is configured to burn a mixture of intake air and fuel supplied from an intake path 30 in each cylinder 11 according to a predetermined combustion order. Specifically, the engine body 10 has a cylinder block 12 and a cylinder head 13 mounted on the cylinder block 12 .
The aforementioned four cylinders 11 are formed inside the cylinder block 12 . The four cylinders 11 are arranged along the central axis direction of the crankshaft 15 (cylinder row direction). Note that FIG. 1 shows only one cylinder.

A piston 14 is slidably inserted into each cylinder 11 . Each piston 14 is connected with the crankshaft 15 via a connecting rod 141 . Each piston 14 defines a combustion chamber 16 with cylinder 11 and cylinder head 13 . The term "combustion chamber" as used herein is not limited to the space formed when the piston 14 reaches compression top dead center. The term "combustion chamber" is used broadly.

For example, two intake ports 18 are formed in the cylinder head 13 for each cylinder 11 . Only one intake port 18 is shown in FIG. The two intake ports 18 are adjacent to each other in the cylinder row direction and communicate with the corresponding cylinders 11, respectively.

An intake valve 21 is arranged in each of the two intake ports 18 . The intake valve 21 opens and closes between the combustion chamber 16 and each intake port 18 . The intake valve 21 is opened and closed at a predetermined timing by an intake valve mechanism.

In this configuration example, the intake valve mechanism has a variable valve mechanism 23, as shown in FIG. The variable valve mechanism 23 is configured to continuously change the rotation phase of the intake camshaft within a predetermined angular range. As a result, the opening timing and closing timing of each intake valve 21 continuously change.

For example, two exhaust ports 19 are formed in the cylinder head 13 for each cylinder 11 . Only one exhaust port 19 is shown in FIG. The two exhaust ports 19 are adjacent in the cylinder row direction and communicate with the corresponding cylinders 11 respectively.

An exhaust valve 22 is arranged in each of the two exhaust ports 19 . The exhaust valve 22 opens and closes between the combustion chamber 16 and each exhaust port 19 . The exhaust valve 22 is opened and closed at a predetermined timing by an exhaust valve mechanism.

In this configuration example, the exhaust valve mechanism has a variable valve mechanism 24, as shown in FIG. The variable valve mechanism 24 is configured to continuously change the rotational phase of the exhaust camshaft within a predetermined angular range. As a result, the opening timing and closing timing of each exhaust valve 22 continuously change.

An injector 6 is attached to the cylinder head 13 for each cylinder 11 . Each injector 6 is, for example, a multi-hole type fuel injection valve in this configuration example, and is configured to directly inject fuel into each combustion chamber 16 .

A fuel supply system 61 is connected to each injector 6 . The fuel supply system 61 includes a fuel tank 63 that stores fuel and a fuel supply path 62 that connects the fuel tank 63 and the injector 6 to each other. A fuel pump 65 and a common rail 64 are interposed in the fuel supply path 62 .

A spark plug 25 is attached to the cylinder head 13 for each cylinder 11 . The spark plug 25 is mounted so that its tip faces the combustion chamber 16 and forcibly ignites the air-fuel mixture in the combustion chamber 16 .

Also, the intake path 30 according to the present embodiment is connected to one side surface (specifically, the front side surface) of the engine body 10 and communicates with the intake port 18 of each cylinder 11 . That is, the intake path 30 is a passage through which intake air introduced into the combustion chamber 16 flows, and is therefore connected to the combustion chamber 16 via each intake port 18 .

A throttle valve 32 is arranged between the air cleaner 31 and the surge tank 38 in the intake path 30 . The throttle valve 32 is configured to adjust the amount of fresh air introduced into the combustion chamber 16 by adjusting its opening.

A supercharger 34 is arranged in the intake path 30 downstream of the throttle valve 32 . The supercharger 34 is configured to supercharge the intake air introduced into each combustion chamber 16 . In this configuration example, the supercharger 34 is a mechanical supercharger driven by the engine 1 (specifically, power transmitted from the crankshaft 15). The supercharger 34 is configured as, for example, a two-shaft rotor type Roots blower.

For example, an electromagnetic clutch 34 a is interposed between the supercharger 34 and the crankshaft 15 . The electromagnetic clutch 34a transmits driving force between the supercharger 34 and the crankshaft 15, and interrupts transmission of the driving force. As will be described later, control means (not shown) such as an ECU (Engine Control Unit) switches between disengagement and connection of the electromagnetic clutch 34a, thereby switching the supercharger 34 between an on state and an off state. That is, by switching the supercharger 34 between an on state and an off state, the engine 1 operates to supercharge the intake air to be introduced into the combustion chamber 16 (supercharging operation) and to supercharge the intake air to be introduced into the combustion chamber 16. Operation without supercharging (natural aspiration operation) can be switched.

An intercooler 36 is arranged in the intake path 30 downstream of the supercharger 34 . The intercooler 36 contains a core (not shown) configured to exchange heat with intake air that has passed through the supercharger 34, and cools the intake air that has been compressed in the supercharger 34. is configured to The intercooler 36 here is, for example, water-cooled.

Further, the intake path 30 is arranged downstream of the air cleaner 31 as a passage connecting various devices incorporated in the intake path 30 and guides the intake air purified by the air cleaner 31 to the supercharger 34 . A passage 33, a second passage 35 that guides intake air compressed by the supercharger 34 to an intercooler 36, and a third passage 37 that guides intake air cooled by the intercooler 36 to a surge tank (intake air collecting portion) 38. have.

In the intake path 30, the first passage 33, the second passage 35, the third passage 37, and the surge tank 38 are interposed with the supercharger 34 and the intercooler 36 in order from the upstream side along the flow direction of the intake air. It constitutes the "main intake path". Hereinafter, the reference numeral "30A" is attached to the main intake path.

Further, the intake path 30 is provided with a bypass passage 40 that bypasses the supercharger 34 and the intercooler 36 separately from the above-described main intake path 30A. Specifically, the bypass passage 40 branches off from the upstream side of the supercharger 34 in the main intake passage 30A and is connected to the downstream side of the intercooler 36, specifically the surge tank 38 .

The bypass passage 40 is provided with an air bypass valve (hereinafter simply referred to as “bypass valve”) 41 that changes the cross-sectional area of the bypass passage 40 . Bypass valve 41 adjusts the flow rate of intake air flowing through bypass passage 40 by changing the cross-sectional area of bypass passage 40 .

4 and 5 show a comparison of the flow of intake air in the intake path 30 during supercharging and during natural intake.

As shown in FIG. 4, when the turbocharger 34 is turned on (that is, when the electromagnetic clutch 34a is connected), the opening of the bypass valve 41 is appropriately adjusted. As a result, part of the intake air that has passed through the turbocharger 34 in the intake path 30 flows back upstream of the turbocharger 34 through the bypass passage 40 . By adjusting the opening degree of the bypass valve 41 in this way, the reverse flow rate of the intake air can be adjusted. In this configuration example, the supercharger 34, the bypass passage 40, and the bypass valve 41 constitute a supercharging system.

On the other hand, as shown in FIG. 5, when the supercharger 34 is turned off (that is, when the electromagnetic clutch 34a is disconnected), the bypass valve 41 is fully opened. As a result, the intake air flowing through the intake path 30 bypasses the supercharger 34 and flows into the surge tank 38 and is introduced into the combustion chamber 16 via the independent passage 39 . In this case, the engine 1 is non-supercharged, that is, driven by natural aspiration.

On the other hand, as shown in FIG. 1, the exhaust passage 50 is connected to the other side surface (specifically, the rear side surface) of the engine body 10 and communicates with the exhaust port 19 of each cylinder 11. there is The exhaust passage 50 is a passage through which the exhaust gas discharged from the combustion chamber 16 flows. Although not shown in detail, the upstream portion of the exhaust passage 50 constitutes an independent passage that branches for each cylinder 11 . The upstream ends of these independent passages are connected with the exhaust port 19 of each cylinder 11 .

An exhaust purification system having one or more catalytic converters 51 is arranged in the exhaust passage 50 . Catalytic converter 51 includes a three-way catalyst. Note that the exhaust gas purification system is not limited to a configuration including only a three-way catalyst.

An EGR passage 52 that constitutes an external EGR system is connected between the intake passage 30 and the exhaust passage 50 . The EGR passage 52 is a passage for recirculating part of the burned gas to the intake passage 30 . Specifically, the upstream end of the EGR passage 52 is connected to the downstream portion of the catalytic converter 51 in the exhaust passage 50 . On the other hand, the downstream end of the EGR passage 52 is connected to the upstream portion of the supercharger 34 in the intake passage 30 and the downstream portion of the throttle valve 32 .

A water-cooled EGR cooler 53 is arranged in the EGR passage 52 . The EGR cooler 53 is configured to cool the burned gas. The flow rate of burnt gas flowing through the EGR passage 52 is configured to be adjusted by an EGR valve 54 . Although the EGR valve 54 is illustrated as being disposed above the EGR passage 52 in the drawing of FIG. 1, it is actually disposed above the bypass passage 40 as will be described later. ing. By adjusting the opening of the EGR valve 54, it is possible to adjust the recirculation amount of the cooled burned gas, that is, the external EGR gas.

In this configuration example, the EGR system 55 includes an external EGR system including the EGR passage 52 and the EGR valve 54, and the above-described intake-side variable valve mechanism 23 and exhaust-side variable valve mechanism 24. It is composed of an internal EGR system that is composed.

In addition to the fuel pump 65 described above, the engine 1 is also provided with various accessories. Although not shown, the engine 1 includes an alternator that generates an alternating current used in the electric system, an air conditioner for air conditioning, and a water pump that circulates cooling water as such auxiliary equipment. ing.

As shown in FIG. 2, a driving pulley 34d for driving the supercharger 34 is arranged above the right end of the engine body 10. As shown in FIG. Although details are omitted, the drive pulley 34d is constructed and arranged so that a timing belt for driving the turbocharger 34 is wound thereon. In the present embodiment, the mechanical supercharger using the output of the engine body 10 as the power source of the supercharger 34 is used. good too.

Further, an evaporated fuel passage 66 for recirculating the evaporated fuel from the fuel tank 63 is arranged in the intake path 30 . More specifically, as shown in FIG. 1, the vaporized fuel passage 66 extends from the upper portion of the fuel tank 63 through the canister 67 to a purge valve disposed upstream of the supercharger 34 in the first passage 33 of the intake passage 30 . 68 is connected. Note that the canister 67 is a container that temporarily stores the evaporated fuel.

Further, the engine 1 is provided with a blow-by gas reduction system 70 . Specifically, as shown in FIG. 1 , the blow-by gas passage 71 constituting the blow-by gas reduction system 70 is connected at its upstream end to a PCV valve 72 provided on the upper part of the cylinder head cover 26 of the engine body 10 . and the downstream end thereof is connected to the vicinity of the connecting portion of the bypass passage 40 with the first passage 33 . As a feature of the present embodiment, the blow-by gas passage 71 branches upstream of the connecting portion with the bypass passage 40 and connects to the suction side of the supercharger 34 and the first communication passage 73 . A second communication passage 74 is branched between the passage 73 and the bypass passage 40 and connected to the discharge side of the supercharger 34 . A specific configuration example of the first communication passage 73 and the second communication passage 74 of the blow-by gas passage 71 will be described later.

(Structure of intake path)
The configuration of the main parts of the intake path 30 will be described in detail below.

Each part constituting the intake path 30 is arranged along the front side of the engine body 10 , specifically, along the front surfaces of the cylinder head 13 and the cylinder block 12 .

Further, as described above, the intake path 30 includes a plurality of passages (specifically, the first passage 33, the second passage 35, the third passage 37, the surge tank 38, and the independent passage 39) that guide the intake air, Devices such as the feeder 34 and the intercooler 36 are combined with a bypass passage 40 that bypasses these devices. A main intake path 30A that forms the intake path 30 is arranged below the bypass passage 40 .

As described above, the supercharger 34 is configured as a twin-rotor roots blower. That is, as shown in FIG. 6, the turbocharger 34 includes a first rotor 341 extending in the axial direction of the rotating shaft 81 inside the casing 34b, and a central axis extending parallel to the first rotor 341. and a rotor chamber 343 that accommodates the first rotor 341 and the second rotor 342 . Here, the rotating shaft 81 of the second rotor 342 is configured as the rotating shaft of the drive pulley 34d.

Further, as shown in the right sectional view taken along the line VIa-VIa of FIG. 6, an intake port 34c is opened on the intake side of the casing 34b. On the other hand, the intake air compressed by the two rotors 341, 342 is discharged to the second passage 35 shown in FIG.

In this configuration example, the axial direction of each rotating shaft 81 coincides with the direction of the row of cylinders (see FIGS. 2 and 3). Therefore, in the following description, the axial direction (central axis direction) is simply referred to as the cylinder row direction.

Further, as shown in FIGS. 1 and 2, the engine 1 according to the present embodiment integrates the supercharger 34 and the intercooler 36 near the upstream end of the intake port 18 in order to improve the supercharging response. are arranged.

A schematic layout of these components is described below. As shown in FIG. 3 , the supercharger 34 is arranged to face the opposite side (front side) of the engine body 10 with the surge tank 38 interposed therebetween. Between the rear surface of the turbocharger 34 and the front surface of the engine body 10, there is a gap corresponding to the dimensions of the surge tank 38. - 特許庁The first passage 33 extends along the cylinder row direction on the left end side of the supercharger 34 and is connected to the left end portion of the supercharger 34 .

Moreover, as shown in FIG. 2, the supercharger 34 and the intercooler 36 are arranged side by side in this order along the vertical direction and are adjacent to each other in this vertical direction. The second passage 35 extends substantially vertically so as to connect the front portion of the supercharger 34 and the front portion of the intercooler 36 . The surge tank 38 is arranged between the supercharger 34 and the engine body 10 (see FIGS. 3 and 7), and is arranged across a plurality of independent passages 39 from the upstream end of the intake port. They are arranged opposite to each other. The third passage 37 extends through a gap between the intercooler 36 and the supercharger 34 and the engine body 10, and the intercooler 36 is located below the surge tank 38. It connects the rear portion of the intercooler 36 and the bottom portion of the surge tank 38 (see FIG. 7). The bypass passage 40 is formed to extend inward (to the right) of the engine body 10 after branching from the middle of the first passage 33 and extending upward. is connected to the top of the surge tank 38 (see FIGS. 3 and 7).

- Configuration of blow-by gas passage -
A detailed configuration of the blow-by gas passage will be described below with reference to FIGS. 1, 3, and 6 to 10. FIG.

Moisture contained in the burned gas recirculated through the EGR passage 52 may become condensed water in the EGR passage 52 and the bypass passage 40, flow into the first passage 33 from the bypass passage 40, and eventually flow into the supercharger 34. There is

Therefore, as shown in FIG. 8, in the present embodiment, in the blow-by gas return system 70, two communicating passages 73 and 74 branching from the blow-by gas passage 71 are connected through the casing 34b of the turbocharger 34 to the intake side. and a space (annular space) provided in each bearing on the discharge side.

Further, as shown in FIGS. 3 and 7, an introduction path 71a to the first passage 33 of the intake path 30 in the blow-by gas passage 71, and a first communication path 73 and a second communication path 74 branched from the introduction path 71a. Each of the branch passages 73 a and 74 a is formed integrally with the body portion 40 a including the bypass valve 41 in the bypass passage 40 . Furthermore, the first communication passage 73 and the second communication passage 74 connected to the supercharger 34 are oriented in the cylinder row direction of the engine body 10 . Here, the first communication path 73 and the second communication path 74 are provided between the supercharger main body 34b and the pipe portion 40b of the bypass passage 40 disposed above the supercharger main body 34b except for the main body portion 40a. are placed through

In this manner, since the introduction passage 71a of the blow-by gas passage 71 to the first passage 33 and the branch passages 73a and 74a of the first communication passage 73 and the second communication passage 74 are integrally formed, the blow-by gas The layout of the passage 71 and the communication passages 73 and 74 can be configured organically and compactly. Further, since the communicating passages 73 and 74 are arranged in the cylinder row direction, the gas can flow smoothly and the layout of the communicating passages 73 and 74 can be made compact.

FIG. 9 schematically shows a configuration example of a blow-by gas reduction system 70 according to this embodiment.

First, as shown in FIG. 9, in the turbocharger 34 according to the present embodiment, each sealing member (oil seal) 91 for sealing the inner side surface (rotor chamber 343 side) of the two bearings 83 on the suction side. An annular space 34f is provided to expose the . Further, as shown in FIG. 10, which is an enlarged view of the region A of FIG. 9, an annular stepped portion 34f1 is provided in the casing 34b of the supercharger 34 in each annular space 34f on the suction side. The annular stepped portion 34f1 increases the volume of the annular space portion 34f. The annular stepped portion 34f1 can be formed by cutting the inner portion of each sealing material 91 in the casing 34b using an end mill or the like.

A first communication passage 73 branching from the blow-by gas passage 71 is connected to each annular space 34f formed by enlarging the circumference of the bearing 83 on the intake side of the supercharger 34 . Furthermore, as shown in the right sectional view of FIG. 6, the two annular spaces 34f are connected to each other by a single first connection path 34g. By doing so, it is possible to easily perform processing (for example, drilling) for connecting the two annular spaces 34f. Grease is applied to each bearing portion 83 .

On the other hand, on the inside (rotor chamber 343 side) of the two bearing portions 84 on the discharge side of the supercharger 34, the inner side (rotor chamber 343 side) of each outer seal material 92 that seals the inner side surface of the bearing portion 84 is provided. An annular space 34h is formed by a side surface and an outer side surface of an inner seal member 93 that seals each rotary shaft 81 outside the partition wall on the discharge side of the rotor chamber 343. As shown in FIG.

A second communication passage 74 branching from the blow-by gas passage 71 is connected to each annular space 34 h around the bearing 84 on the discharge side of the supercharger 34 . As shown in the left sectional view of FIG. 6, the two annular spaces 34h are connected to each other by a second connection path 34i. Each bearing 84 is lubricated with lubricating oil stored in the gear chamber in the casing 34b.

Here, the upstream end of the blow-by gas passage 71 is connected to a PCV valve 72 provided on the cylinder head cover 26 of the engine body 10, as shown in FIG. The PCV valve 72 is connected to an oil separator 27 arranged inside the cylinder head cover 26, as schematically shown in FIG.

-Action/effect of blow-by gas reduction system-
In this embodiment, as the blow-by gas return system 70, the communication passages 73 and 74 branching from the blow-by gas passage 71 are connected to the suction side bearing portion 83 and the discharge side bearing portion of the supercharger 34 as described above. 84 are connected to annular spaces 34f and 34h provided in the vicinity of each of them. Thereby, the following actions and effects can be obtained.

(when supercharging)
First, when the supercharger 34 is performing a supercharging operation, the internal pressure of the annular space 34h on the discharge side shown in FIG. positive pressure. On the other hand, the internal pressure of the suction-side annular space 34f, although negative, is higher than the negative pressure at the branch of the first communication passage 73 from the blow-by gas passage 71, so it is relatively positive.

As a result, the intake air in the annular space portions 34f and 34h is sucked out from the inside through the first communication passage 73 and the second communication passage 74 to the blow-by gas passage 71, respectively. Therefore, dust, condensed water, and the like, mainly due to EGR gas, can be sucked out from the bearings 83 and 84 . Further, depending on the operation mode, when the supercharging operation by the supercharger 34 continues, it is possible to prevent dust, condensed water, and the like from entering the annular spaces 34f and 34h.

(at the time of natural aspiration)
Next, when the supercharger 34 is not performing a supercharging operation, various investigations by the inventors of the present application show that the internal pressure (negative pressure) of the discharge-side annular space 34h shown in FIG. And even at medium load, there is almost no difference from the pressure (negative pressure) at the branching portion of the second communication passage 74 from the blow-by gas passage 71 . On the other hand, although the internal pressure of the suction-side annular space 34f is a negative pressure, it is slightly lower than the negative pressure at the branch of the first communication passage 73 and the blow-by gas passage 71 under low and medium loads. Since it is low, it becomes a little negative pressure.

As a result, almost no intake air flows into or out of the discharge-side annular space 34h, while gas flowing through the blow-by gas passage 71 is introduced into the intake-side annular space 34f. be. As a result, as schematically shown in FIG. 9, the gas from the blow-by gas passage 71 passes through the first communication passage 73 and is introduced into the annular space 34f. At this time, since the blow-by gas passing through the blow-by gas passage 71 has already passed through the oil separator 27, most of the oil components are removed, but some oil mist remains in the gas. Therefore, the lubricating properties of the sealing material 91 exposed from the suction-side annular space 34f and the bearing 83 in the vicinity thereof can be enhanced by the oil mist.

Further, as schematically shown in FIG. 9, the branching portion of the first communication passage 73 to the blow-by gas passage 71 is connected substantially linearly to the blow-by gas passage 71, while the blow-by gas passage 74 of the second communication passage 74 is connected to the blow-by gas passage 71 substantially linearly. The branched portion with the gas passage 71 is connected in a crank shape, for example. As a result, the oil component of the blow-by gas flowing from the upstream of the blow-by gas passage 71 easily flows into the first communication passage 73 , but hardly flows into the second communication passage 74 . In this way, by inertial separation (gas-liquid separation) of the oil component in the blow-by gas, when the supercharger 34 is not performing a supercharging operation, the oil mist is removed from the annular space 34f on the intake side. can increase the supply of

The inventors of the present application have found that the pressure difference between the annular spaces 34f and 34h and the blow-by gas passage 71 when the turbocharger 34 is not performing a supercharging operation depends on the operating conditions of the engine 1. are confirmed to be relatively replaced.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to improve the lubricating property of the bearing portion and sealing material of a supercharger rotor by means of oil mist, and to prevent the entry of dust and condensed water into the bearing portion. is useful as

1 engine (engine with mechanical supercharger)
10 Engine Body 17 Crankcase 26 Cylinder Head Cover 27 Oil Separator 30 Intake Path 32 Throttle Valve 33 First Path 34 Supercharger (Driving Type Supercharger)
34a electromagnetic clutch 34b casing (supercharger body)
34c Intake port 34d Drive pulley 34e Discharge port 34f Annular space (space)
34f1 Annular step 34g First connection path 34h Annular space (space)
34i Second connection paths 341, 342 Supercharging rotor 343 Rotor chamber (working chamber)
35 2nd passage 36 intercooler 37 3rd passage 38 surge tank (intake collecting part)
39 independent passage 40 bypass passage (air bypass passage)
40a body portion 40b pipe portion 41 bypass valve (air bypass valve)
70 blow-by gas reduction system (blow-by gas device)
71 blow-by gas passage 71a introduction passage 72 PCV valve 73 first communication passage (communication passage)
73a branch path 74 second communication path (communication path)
74a branch path 81 rotating shaft 83 bearing (suction side)
84 bearing (discharge side)
91 sealing material 92 outer sealing material (sealing material)
93 inner sealing material

Claims (4)

a driven supercharger having a supercharger rotor rotatably disposed in a working chamber of a supercharger body via a suction-side bearing and a discharge-side bearing;
a bypass passage branching from a downstream portion of the throttle valve in the intake passage, bypassing the driven supercharger and connected to the intake collecting portion, and having a bypass valve that opens during non-supercharging;
A turbocharger comprising a blow-by gas passage for introducing blow-by gas discharged from a crankcase of an engine to a portion downstream of the throttle valve in the intake passage via a PCV valve, and an EGR system for recirculating the burned gas. A blow-by gas device for an engine with
The supercharger main body has a space provided near each bearing,
The blow-by gas passage is provided with a first communication passage and a second communication passage branched from a portion downstream of the PCV valve in the blow-by gas passage and connected to the respective spaces ,
An introduction passage to the intake passage in the blow-by gas passage and branch passages of the first communication passage and the second communication passage branched from the introduction passage are integrated with a body portion including the bypass valve in the bypass passage. A blow-by gas system for a supercharged engine, formed in In the blow-by gas device for a supercharged engine according to claim 1,
The first communication passage and the second communication passage are oriented in the cylinder row direction of the engine and connect the turbocharger main body and the main body portion of the bypass passage disposed above the supercharger main body. A blow-by gas device for a supercharged engine, which is disposed between pipes excluding. In the blow-by gas device for a supercharged engine according to claim 1 or 2,
The supercharging rotor consists of two supercharging rotors,
The space near each bearing on the suction side of the two supercharging rotors is an annular space formed adjacent to a sealing material disposed near each bearing,
A blow-by gas device for a supercharged engine, wherein the annular spaces are connected by a single first connection path extending from the first communication path. In the blow-by gas device for a supercharged engine according to claim 1 or 2,
The supercharging rotor consists of two supercharging rotors,
The space near the discharge-side bearings of the two supercharging rotors is an annular space formed between double seals arranged near the bearings,
A blow-by gas device for a supercharged engine, wherein each of the annular spaces is connected by a second connection path and connected to the second communication path.

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