JP7206640B2 - supercharged engine - Google Patents

Description

The present invention relates to a supercharged engine.

In Patent Document 1 below, a balance hole for canceling negative pressure applied to a seal material disposed in a bearing portion of a supercharger rotor in a mechanical supercharger is connected to an intake path upstream of a throttle valve, and the balance hole A configuration is described in which the hole suppresses a change in the posture of the sealing material to prevent deterioration of the sealing performance.

JP-A-04-203214

In recent years, there is a case of adopting a configuration in which EGR (Exhaust Gas Recirculation) gas is introduced into the intake passage upstream of the supercharger, and dust such as soot and condensed water due to the EGR gas is generated in each bearing and this. It may adversely affect each sealing material adjacent to the . Therefore, it is important to ensure the lubricity and sealing performance of each bearing portion and each seal material.

SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, prevents dust and condensed water from entering the bearing portion of the supercharger rotor and the sealing material, and suppresses deterioration of the sealing performance due to changes in the posture of the sealing material. aim.

In order to achieve the above object, the present invention provides a configuration in which an annular space adjacent to a seal material is provided in the bearing portion of the supercharging rotor, and intake negative pressure downstream of the throttle valve is applied to the annular space provided. do.

Specifically, the present invention is aimed at a supercharged engine, and has taken the following solutions.

That is, the technology disclosed is a supercharger disposed downstream of a throttle valve in an intake passage and rotatably disposed inside a turbocharger main body via bearings on the suction side and the discharge side. A driven turbocharger having a feed rotor, and an EGR having a downstream end connected to a portion upstream of the driven turbocharger in the intake path and downstream of the throttle valve to recirculate part of the burned gas. and a passage , wherein the supercharger main body includes a sealing material that seals each of the bearing portions, and a passage that is adjacent to the sealing material and on the rotating shaft of the supercharging rotor. A suction-side annular space and a discharge-side annular space are formed around the suction -side annular space. Each of the first communication passage and the second communication passage branches from a main passage connected to a downstream portion of the throttle valve in the intake passage, and when supercharging, the annular Intake air in the space is sucked out to the main passage through the first communication passage and the second communication passage.

Thus, an annular space adjacent to the seal material of the bearing is provided inside the supercharger main body, and the provided annular space is provided with a communication passage connected to the downstream portion of the throttle valve in the intake path. Therefore, the intake negative pressure downstream of the throttle valve can be applied to the annular space. The action of this negative pressure can prevent dust and condensed water from entering the sealing material and the bearing, thereby improving the durability of the sealing material and the bearing. Furthermore, the intake negative pressure downstream of the throttle valve can be applied to the annular space through the communication passage, thereby suppressing deterioration of sealing performance due to changes in the posture of the seal material caused by changes in the pressure (atmospheric pressure). can be done.

The suction-side annular space may be formed by an annular stepped portion provided in the supercharger main body and the sealing material.

According to this, the above effects can be obtained for the suction-side bearing portion and sealing material in the turbocharger main body.

The discharge-side annular space may be formed by the sealing material and an inner sealing material disposed inside the sealing material.

According to this, the above effects can be obtained for the discharge-side bearing portion, the sealing material, and the inner sealing material in the turbocharger main body.

According to the present invention, it is possible to prevent dust and condensed water from entering the bearing portion of the supercharging rotor and the sealing material, and to suppress deterioration of the sealing performance due to a change in the posture of the sealing material.

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 a turbocharger maintenance mechanism 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 the gas passing through the supercharger 34 to cool the intake air 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 an EGR gas introduction portion 33 a positioned upstream of the turbocharger 34 in the intake passage 30 and downstream 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, as a feature of this embodiment, the engine 1 is provided with a supercharger maintenance mechanism 70 for automatically maintaining the supercharger 34 . As shown in FIG. 1 , the supercharger maintenance mechanism 70 has a main passage 71 , a first communication passage 73 and a second communication passage 74 . One end of the main passage 71 is connected to the upstream side of the connecting portion of the bypass passage 40 to the first passage 33 . The other end of the main passage 71 branches into a first communication passage 73 connected to the suction side of the supercharger 34 and a second communication passage 74 connected to the discharge side of the supercharger 34 . A specific configuration example of the first communication path 73 and the second communication path 74 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 turbocharger maintenance mechanism -
A detailed configuration of the turbocharger maintenance mechanism 70 according to the present embodiment will be described below with reference to FIGS. 1, 6, and 8 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, in the present embodiment, as shown in FIGS. 1 and 8, as the supercharger maintenance mechanism 70, space portions (annular space portions) provided in the bearing portions on the suction side and the discharge side of the supercharger 34 are provided. , and a main passage 71 connecting two communication passages 73 and 74 communicating through the casing 34b, respectively, is connected to the upstream portion of the bypass passage 40 branching off from the first passage 33. As shown in FIG.

FIG. 9 schematically shows a configuration example of a supercharger maintenance mechanism 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 intake 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 branched from the main 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 main 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.

-Function/Effect of Turbocharger Maintenance Mechanism-
In this embodiment, as the supercharger maintenance mechanism 70, the first communication path 73 and the second communication path 74 are connected to the suction side bearing portion 83 and the discharge side bearing portion 84 of the supercharger 34 as described above. are connected to annular space portions 34f and 34h provided in regions near the respective regions. 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, although the internal pressure of the suction-side annular space 34f is negative, it is higher than the negative pressure at the branch of the first communication passage 73 from the main passage 71, so it is relatively positive.

As a result, the intake air in the annular spaces 34f and 34h is sucked out from the inside through the first communication passage 73 and the second communication passage 74 to the main 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 under medium load, there is almost no difference from the pressure (negative pressure) at the branching portion of the second communication passage 74 from the main passage 71 . On the other hand, although the internal pressure of the suction-side annular space 34f is negative, it is slightly lower than the negative pressure at the branch of the first communication passage 73 from the main passage 71 under low and medium loads. Therefore, the pressure becomes slightly negative.

As a result, almost no intake air flows into or out of the discharge-side annular space 34h, while intake air flowing through the main passage 71 is introduced into the intake-side annular space 34f. . As a result, as schematically shown in FIG. 9, the intake air from the main passage 71 passes through the first communication passage 73 and is introduced into the annular space 34f. As a result, it is possible to suppress the deterioration of the sealing performance due to the posture change due to the pressure change of the sealing material.

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 The present invention can prevent dust and condensed water from entering the bearing portion and sealing material of a supercharged rotor, and can suppress deterioration in sealing performance due to changes in the posture of the sealing material, and is useful as a supercharged engine. .

1 engine (engine with mechanical supercharger)
10 Engine Body 17 Crankcase 26 Cylinder Head Cover 30 Intake Path 32 Throttle Valve 33 First Path 33a EGR Gas Introduction Port 34 Turbocharger (Driving Type Turbocharger)
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 passages 341, 342 Supercharging rotor 343 Rotor chamber 35 Second passage 36 Intercooler 37 Third passage 38 Surge tank 39 Independent passage 40 Bypass passage (air bypass passage)
41 bypass valve (air bypass valve)
70 turbocharger maintenance mechanism 71 main passage 73 first communication passage (communication passage)
74 Second communication path (communication 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 (3)

A driven supercharger having a supercharger rotor disposed downstream of a throttle valve in an intake passage and rotatably disposed inside a supercharger body via bearings on the suction side and the discharge side. a feeder;
an EGR passage whose downstream end is connected to a portion of the intake passage upstream of the drive-type supercharger and downstream of the throttle valve, and which recirculates part of the burned gas ;
A supercharged engine comprising
The supercharger main body includes a sealing material for sealing each of the bearings, and annular spaces on a suction side and a discharge side adjacent to the sealing material and formed around a rotating shaft of the supercharging rotor. and
The suction-side annular space is connected to a first communication path, and the discharge-side annular space is connected to a second communication path,
each of the first communication passage and the second communication passage branches off from a main passage connected to a downstream portion of the throttle valve in the intake passage;
A supercharged engine, wherein, during supercharging, intake air in the annular space is sucked into the main passage through the first communication passage and the second communication passage. In the supercharged engine according to claim 1,
The turbocharged engine, wherein the suction-side annular space is formed by an annular stepped portion provided in the turbocharger main body and the sealing material. In the supercharged engine according to claim 2,
The supercharged engine, wherein the annular space on the discharge side is formed by the sealing member and an inner sealing member arranged inside the sealing member.

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