JP7151209B2 - Intake system for multi-cylinder engine - Google Patents

Description

The present invention relates to an intake system for a multi-cylinder engine.

Patent Document 1 below describes a configuration in which an intercooler is arranged above a mechanical supercharger arranged on the side of an engine body and close to the outside of an intake manifold. The inlet and outlet of this intercooler are arranged in the vertical direction of the engine body, and this outlet is connected to one longitudinal end of the surge tank.

JP-A-09-242548

The intercooler described in Patent Document 1 is a so-called vertical type intercooler in which the inlet and outlet are arranged in the vertical direction of the engine body. ) In the case of a configuration in which gas is introduced, condensed water generated by the intercooler stays inside the intercooler.

At this time, when the engine is accelerated, the remaining condensed water flows into the intake manifold at once, causing a problem of misfiring in some cylinders.

The present invention solves the above-mentioned conventional problems, and in a configuration in which EGR gas is introduced into an intake pipe, suppresses the occurrence of misfires due to condensed water especially generated by an intercooler, and is compact without increasing intake air flow resistance. It is an object of the present invention to realize an intake path layout that makes it possible to reduce airflow.

In order to achieve the above object, the present invention provides a flat U-shaped connection intake pipe at a portion of an intake pipe of an engine connected to one end side of a row of cylinders on the side of a surge tank. The bottom surface of is lowered on the downstream side.

Specifically, the present invention is directed to an intake system for a multi-cylinder engine, and has taken the following solutions.

That is, the first invention includes a turbocharger connected to an intake pipe provided in a multi-cylinder engine, an intercooler connected to the downstream side of the turbocharger in the intake pipe, and a turbocharger arranged downstream of the intercooler. and an EGR passage for introducing EGR gas upstream of an intercooler in an intake pipe. The intercooler is arranged in parallel with the surge tank and connected by a connecting intake pipe. The connection intake pipe is formed in a U shape in plan view and is connected to one end side of the row of cylinders of the surge tank. The bottom surface of the intercooler is inclined so that the downstream side is lower than the upstream side. The bottom surface of the connecting intake pipe is lower than or the same as the lowest part of the bottom surface of the intercooler.

According to this, the bottom surface of the intercooler, which is arranged in parallel with the surge tank and connected by the connection intake pipe, is inclined so that the downstream side is lower than the upstream side, and is formed in a plane U shape to prevent the surge. The bottom surface of the connecting intake pipe connected to one end side of the cylinder row of the tank is lower than or equal to the lowest part of the bottom surface of the intercooler. With this configuration, retention of condensed water, particularly due to EGR gas, in the intake pipe is reduced. As a result, the accumulated condensed water does not flow into the intake manifold all at once, so it is possible to prevent misfires from occurring in some of the cylinders. Moreover, since the surge tank and the intercooler are arranged in parallel without increasing the intake air flow resistance, the size can be reduced.

In the first aspect of the invention, the intake regulating valve is connected to the intake pipe upstream of the intercooler, and the intake regulating valve is disposed adjacent to the surge tank in a plan view .

According to this, the parallel arrangement of the intake regulating valve and the surge tank arranged close to each other in the intercooler can further enhance compactness.

In the above first invention, the upstream portion of the intake regulating valve in the intake pipe is arranged above the engine body, and the upstream portion of the intake regulating valve is arranged so as to slope downward from the middle. It is

According to this, it is possible to effectively suppress retention of condensed water by the downwardly inclined supercharging path including the intake pipe of the supercharger.

In a second invention according to the first invention, the intercooler may be a water-cooled intercooler using liquid refrigerant.

According to this, the water-cooled intercooler is more likely to produce condensed water than the air-cooled intercooler, so the effect of the present invention is remarkable.

According to the present invention, it is possible to suppress the occurrence of misfires due to condensed water generated by the intercooler, and realize an intake path layout that enables a compact design without increasing intake air flow resistance.

FIG. 1 is a schematic configuration diagram showing an engine according to one embodiment of the present invention. FIG. 2 is a plan view including an intake path in the engine according to one embodiment of the present invention. FIG. 3 is a left side view including an intake path in the engine according to one embodiment of the present invention. FIG. 4 is an upper left front perspective view including an intake path in the engine according to one embodiment of the present invention. FIG. 5 is an upper left rear perspective view showing a surge tank and an intake passage in the engine according to one embodiment of the present invention. 6 is a cross-sectional perspective view taken along the line VI-VI of FIG. 5. FIG. FIG. 7 is a cross-sectional view taken along line VII--VII of FIG. FIG. 8 is a cross-sectional view taken along line VIII--VIII of 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 is a multi-cylinder engine with a supercharger according to the present embodiment, and here schematically shows the configuration of an engine with a supercharger (hereinafter simply referred to as "engine") 1. As shown in FIG.

The engine 1 is, for example, a four-stroke internal combustion engine mounted on an automobile, and includes a turbocharger 32 as shown in FIG. The fuel for the engine 1 is not particularly limited, but light oil is used in this embodiment.

Although not shown in detail, the engine 1 includes, for example, four cylinders (cylinders) 11 arranged in a row. It is configured as a so-called in-line 4-cylinder longitudinally mounted engine that is mounted side by side. 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 length direction, and the engine width direction substantially coincides with the vehicle width direction. ing. The engine 1 is not limited to an in-line four-cylinder longitudinal engine, and the present invention can be applied to an in-line multi-cylinder longitudinal or transverse engine.

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 length direction).

Hereinafter, unless otherwise specified, the front side refers to the front side in the longitudinal direction of the vehicle (engine front side), the rear side refers to the rear side in the longitudinal direction of the vehicle (engine rear side), and the left side refers to the width direction of the vehicle. The left side is indicated when facing forward, and the right side indicates the right side when facing forward in the vehicle width direction.

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 has an engine body 10 having four cylinders 11, and an intake path 30 which is arranged on the left side of the engine body 10 and which is composed of an intake pipe communicating with each cylinder 11 via an intake port 18. , and an exhaust passage 50 arranged on the right side of the engine body 10 and communicating with each cylinder 11 through an exhaust port 19 .

In this configuration example, the intake path 30 is an intake system in which a plurality of passages for introducing fresh air and exhaust air (hereinafter referred to as intake air) and devices such as a turbocharger 32 and an intercooler 37 are combined to form a unit. constitutes

The engine body 10 is configured to burn the intake air supplied from the intake path 30 and the fuel injected from the injector 6 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 23 .

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 24 .

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

Further, the intake path 30 according to the present embodiment is connected to one side surface (specifically, the left 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 .

Between the air cleaner 31 and the surge tank 38 in the intake path 30 are, from the upstream side, a compressor wheel (hereinafter referred to as a compressor) 32a of the turbocharger 32, an intake adjustment valve 33 normally in a fully open state, and an intercooler. 37 are arranged in sequence. The intake control valve 33 is configured to adjust the recirculation amount of the burned gas (EGR gas) introduced into the combustion chamber 16 by adjusting the degree of opening thereof.

The intercooler 37 accommodates a core (not shown) configured to exchange heat with intake air that has passed through the turbocharger 32, and is configured to cool the intake air compressed in the turbocharger 32. It is The intercooler 37 may be either water-cooled or air-cooled, and from the viewpoint of cooling efficiency, the intercooler 37 is of the water-cooled type using liquid refrigerant.

On the other hand, as shown in FIG. 1 , the exhaust passage 50 is connected to the other side surface (specifically, the right side surface) of the engine body 10 and communicates with the exhaust port 19 of each cylinder 11 . 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 to the exhaust port 19 of each cylinder 11 .

The exhaust passage 50 includes the turbine 32b of the turbocharger 32 described above, a diesel oxidation catalyst (DOC) 51 that oxidizes nitrogen monoxide (NO), carbon monoxide (CO), hydrocarbons (HC), etc., and traps fine particles. An exhaust cleaning system having a diesel particulate filter (DPF) 52 for collecting and an exhaust shutter valve 53 for regulating the flow rate of the exhaust is provided. A waste gate valve 54 is arranged in the exhaust passage 50 for bypassing the exhaust gas from the turbocharger 32 to the turbine 32b. A variable capacity turbocharger can be used as the turbocharger 32, and depending on the specifications, the wastegate valve 54 can be omitted.

Further, on the downstream side of the DPF 52, a urea SCR (Selective Catalytic Reduction) for purifying nitrogen oxides (NO _x ) and a slip catalyst for oxidizing surplus ammonia (NH ₃ ) from the urea SCR are appropriately provided. good too. A urea tank is attached to the urea SCR (Selective Catalytic Reduction).

The intake passage 30 of this configuration example includes an internal EGR (high pressure EGR) passage 55 that introduces exhaust gas from the exhaust passage 50 from the vicinity of an exhaust manifold (not shown) to a downstream portion of the intercooler 37 in the intake passage 30, An external EGR (low pressure EGR) passage 56 for introducing exhaust gas from the downstream side of the DPF 52 in the passage 50 to the upstream side of the compressor 32 a of the turbocharger 32 is provided. The internal EGR passage 55 and the external EGR passage 56 are passages for recirculating part of the burned gas to the intake passage 30, respectively.

For example, a water-cooled low-pressure EGR cooler 57 is arranged in the external EGR passage 56 . A low-pressure EGR cooler 57 cools the burned gas. The amount of recirculated burned gas flowing through the external EGR passage 56 is adjusted by an external EGR valve 58 arranged between the low-pressure EGR cooler 57 and the connecting portion of the external EGR passage to the intake path 30 .

On the other hand, the amount of recirculated burned gas flowing through the internal EGR passage 55 is adjusted by an internal EGR valve 59 provided in the internal EGR passage 55 .

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

Each part of the intake pipe that constitutes the intake path 30 is arranged along the left side of the engine body 10 , specifically along the left side surfaces of the cylinder head 13 and the cylinder block 12 . A portion of the intake path 30 from the compressor 32a of the turbocharger 32 to the intercooler 37 is arranged from the right side to the left side of the engine body 10 so as to pass over the upper side thereof.

2, 3, and 4 are a plan view, a left side view, and a left side front perspective view, respectively, of the engine 1 according to this embodiment. As shown in FIGS. 2 to 4, the portion of the intake passage 30 from the turbocharger 32 to the intake regulating valve 33, that is, the first passage 30a, which is the upstream portion of the intake regulating valve 33, is arranged above the engine body 10. It is arranged so that it becomes a downward slope from the middle.

Further, the intercooler 37 is arranged in parallel with the surge tank 38 and is connected to the surge tank 38 by a connection intake pipe 30b. Incidentally, the connection intake pipe 30b between the intercooler 37 and the surge tank 38 may be called an introduction passage 30b. The connection intake pipe 30b is formed in a U shape in plan view and is connected to the front side of the cylinder row of the surge tank 38 . The bottom surface of the intercooler 37 is inclined so that the downstream side (front side) is lower than the upstream side (rear side). The inner bottom surface of the connecting intake pipe 30b is lower than or the same as the lowest portion (downstream end) of the inner bottom surface of the intercooler 37 . That is, the inner bottom surface of the connecting intake pipe 30 b is arranged so as not to be higher than the inner bottom surface of the intercooler 37 .

Furthermore, as shown in FIG. 2, the intake regulating valve 33 connected to the upstream side of the intercooler 37 is arranged close to the surge tank 38 in plan view.

In this manner, the intercooler 37 is arranged in parallel with the surge tank 38 to form a so-called side-entry type, and the bottom surface of the connected intake pipe 30b is made lower than or the same as the bottom surface inside the intercooler 37. As a result, condensed water from low-pressure EGR gas is less likely to stagnate particularly in the intercooler 37 and the connecting intake pipe 30b. In addition, the connection intake pipe 30b has a flat U-shape and is smoothly bent, so that the surge tank 38 and the intercooler 37 are arranged in parallel without increasing the intake air flow resistance. is arranged close to the intake regulating valve 33, the engine 1 can be made compact.

(Surge tank configuration)
FIG. 5 shows the connection intake pipe 30b and the surge tank 38 according to this embodiment, and FIGS. 6 to 8 show cross-sectional configurations taken along lines VI-VI, VII-VII, and VIII-VIII in FIG. there is

As shown in FIG. 6, the surge tank 38 has an intake manifold 39 connected to an opening on the side of the engine body. Further, as shown in FIGS. 6 to 8, inside the surge tank 38, a connection intake pipe (introduction passage) 30b is continuously provided inside and stands upward from the bottom of the surge tank 38. In addition, there is provided a baffle wall portion 38a whose height gradually decreases while extending in the cylinder row direction. The baffle wall portion 38a is erected from the bottom portion of the surge tank 38 in a curved shape that protrudes toward the engine body. In addition, the surge tank 38 is formed to have a large width and a large cross-sectional volume on the front side of the row of cylinders into which intake air flows. On the other hand, the surge tank 38 is formed to have a narrower width and a smaller cross-sectional volume toward the rear end of the cylinder row.

The members constituting the surge tank 38 including the baffle wall portion 38a and the intake manifold 39 are not particularly limited. It also becomes easy to integrally form with the tank 38 .

With this configuration, the baffle wall portion 38a is recessed inside the surge tank 38, so that the flow resistance of the intake air due to the formation of the baffle wall portion 38a is reduced. Furthermore, by reducing the cross-sectional volume of the surge tank 38 on the downstream side, it is possible to ensure good distribution of condensed water.

INDUSTRIAL APPLICABILITY The present invention suppresses the occurrence of misfires due to condensed water from the intercooler, and realizes a compact intake path layout without increasing intake flow resistance, and is useful as an intake device for a multi-cylinder engine. is.

1 engine (engine with supercharger)
10 engine body 30 intake path (intake pipe)
30a First passage 30b Connection intake pipe (introduction passage)
31 Air cleaner 32 Turbocharger 32a Compressor wheel 32b Turbine wheel 33 Intake control valve 37 Intercooler 38 Surge tank 38a Baffle wall 39 Intake manifold 50 Exhaust passage 55 Internal EGR passage 56 External EGR passage

Claims (2)

a turbocharger connected to an intake pipe provided in a multi-cylinder engine;
an intercooler connected downstream of the turbocharger in the intake pipe;
a surge tank disposed downstream of the intercooler;
An intake device for a multi-cylinder engine, comprising an EGR passage for introducing EGR gas upstream of the intercooler in the intake pipe,
The intercooler is arranged in parallel with the surge tank and connected by a connecting intake pipe,
The connection intake pipe is formed in a U shape in plan view and is connected to one end side of the cylinder row of the surge tank,
The bottom surface of the intercooler is inclined so that the downstream side is lower than the upstream side,
the bottom surface of the connecting intake pipe is lower than or the same as the lowest portion of the bottom surface of the intercooler ;
an intake adjustment valve is connected to an upstream side of the intercooler in the intake pipe,
The intake control valve is disposed adjacent to the surge tank in a plan view,
A portion of the intake pipe on the upstream side of the intake adjustment valve is arranged above the engine body,
An intake system for a multi-cylinder engine, wherein an upstream portion of the intake control valve is disposed so as to slope downward from the middle thereof . In the intake device for a multi-cylinder engine according to claim 1 ,
The intercooler is an intake device for a multi-cylinder engine, which is a water-cooled intercooler using a liquid coolant.

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