JP4954113B2 - Blowby gas recirculation structure and internal combustion engine having the same - Google Patents

Description

  The present invention relates to a blowby gas recirculation structure and an internal combustion engine including the same.

Conventionally, as this type of blow-by gas recirculation structure, as disclosed in Patent Document 1, a distribution passage for distributing blow-by gas to each intake port is formed in a flange portion attached to the cylinder head of the intake manifold. What has been proposed.
In this blow-by gas recirculation structure, the blow-by gas can be warmed by the heat transmitted from the cylinder head to the mounting flange, and the external piping for recirculating the blow-by gas to the intake system can be greatly shortened. It is supposed that coagulation can be prevented.
In general, since the outside of the engine is exposed to the outside air, when an external pipe is used, the blow-by gas flowing in the pipe cools and solidifies to form water droplets, and the water droplets freeze to block the piping. . For this reason, in order to prevent the blow-by gas from being exposed to the outside air as much as possible, proposals have been made to completely incorporate the blow-by gas passage inside the engine.
From this point of view, the applicant also has a distribution passage and a cylinder in which blow-by gas flowing in a blow-by gas chamber provided in the cylinder head cover is formed on the mating surface between the cylinder head cover and the cylinder head, as disclosed in Patent Document 2. Proposals have been made to recirculate through a communication passage communicating with each intake port formed in the head.
Japanese Utility Model Publication No. 5-30412 JP 2004-245148 A

  By the way, there are EGR gas and cooling water in addition to blow-by gas to recirculate the medium using external piping, and the demand for abolishing the external piping and incorporating the passage inside the engine will continue to increase. It is thought that it will go. As the demand for incorporating such a passage inside the engine increases, the engine body becomes larger, and therefore a passage structure that can be made as small as possible is desired.

The blow-by gas recirculation structure of the present invention and the internal combustion engine equipped with the blow-by gas recirculation structure are one of the objects for achieving compactness, and the following means are adopted in order to achieve at least a part of the object.
The present invention is a blow-by gas recirculation structure that recirculates blow-by gas to the intake side, and serves as a mating surface when the gas-liquid separation unit capable of separating oil in the blow-by gas and the cylinder head cover are attached to the cylinder head. The cylinder head cover is formed in the wall of the cylinder head cover so as to have an opening on the side, the introduction passage through which the blow-by gas that has passed through the gas-liquid separation unit is introduced, and one end connected to the introduction passage and the other end A recirculation passage formed in the cylinder head to be connected to the intake port; and a seal member that is disposed on the mating surface and hermetically seals the introduction passage and the recirculation passage. And preventing the position of the seal member from being displaced toward the introduction passage by bringing a part of the seal member into contact with the throttle portion. The gist.

  In the blow-by gas recirculation structure of the present invention, a throttle portion is provided at the opening of the introduction passage, and the throttle portion is brought into contact with a part of the seal member, thereby preventing the displacement of the seal member toward the introduction passage. Therefore, it is possible to suppress an increase in the size of the cylinder head cover as compared with a structure that prevents the displacement of the seal member toward the introduction passage without restricting the opening. As a result, downsizing can be achieved. In addition, since the throttle portion is provided in the introduction passage, the flow rate of the blow-by gas returning to the intake side can be adjusted.

Further, in the blowby gas recirculation structure of the present invention, the introduction passage is formed wider than the passage portion connected to the passage portion through which the blowby gas flows and the mating surface side of the passage portion with a step. And the narrowed portion is formed by an orifice member attached to the passage portion in a state having a gap with the inner wall of the widened portion. Position shift can be prevented by inserting the portion into the gap.
In this way, the introduction passage is formed in a stepped shape by the passage portion and the widened portion, the orifice member is attached to the passage portion with a gap between the inner wall of the widened portion, and the seal member is inserted into the gap. Therefore, a compact structure can be easily secured.

Further, in the blow-by gas recirculation structure of the present invention, the throttle portion is connected to the mating surface side of the passage portion through which the blow-by gas flows and is connected to the passage portion with a step so as to be narrower than the passage portion. And a recess is formed on the outer periphery of the reduced width portion so as to surround the reduced width portion, and the seal member is prevented from being displaced by inserting a part thereof into the recess. It can also be.
In this way, the narrowed portion is integrally formed in a stepped shape in the passage portion with the narrowed portion as the reduced width portion, a recess is formed on the outer periphery of the reduced width portion so as to surround the reduced width portion, and the seal member is inserted into the recessed portion Therefore, a compact structure can be easily secured. In addition, since a separate part is not required as the throttle part, an increase in the number of parts can be suppressed.

In the blowby gas recirculation structure of the present invention, the gas-liquid separation part may be formed in the head cover.
In this way, since no separate parts are required as the gas-liquid separator, an increase in the number of parts can be suppressed.

The internal combustion engine of the present invention is configured such that the blow-by gas flowing out from the gap between the piston and the cylinder bore is recirculated to the intake side by the blow-by gas recirculation structure according to any one of claims 1 to 3. It is.
Since the internal combustion engine of the present invention is provided with the blow-by gas recirculation structure of the present invention, the same effect as that provided by the blow-by gas recirculation structure of the present invention, for example, an effect that can be made compact can be achieved. it can.

  Next, the best mode for carrying out the present invention will be described using examples.

FIG. 1 is an enlarged vertical cross-sectional configuration diagram of the main part of the internal combustion engine, and FIG. 2 is an enlarged cross-sectional configuration diagram of the main part of FIG.
In the internal combustion engine 1, a cylinder head 3 is provided on a cylinder block 2, and a cylinder head cover 4 is provided on the upper surface of the cylinder head 3.
A piston 6 is provided in a cylinder bore 5 formed in the cylinder block 2, and an intake valve 7 that is opened and closed by a cam 9 rotated by a camshaft 8 is provided in a valve operating chamber S in the cylinder head 3. It has been. A mounting flange portion 11a of the intake manifold 11 is attached to the intake port 10 formed in the cylinder head 3, and the intake manifold 11 and the intake port 10 are communicated with each other.
In FIG. 1, 12 is a fuel pipe, and 13 is a protective cover for protecting the fuel pipe 12.

The cylinder head cover 4 is attached to the cylinder head 3 by passing a bolt B through a boss portion 4b provided on the outer peripheral side of the cylinder head cover 4. The cylinder head cover 4 is an enlarged sectional view in FIG. Moreover, in FIG. 4, it has a structure which shows the principal part seen from the inside.
A fresh air introduction passage 15, a gas-liquid separation portion 16, and a blow-by gas main passage 17 are respectively formed on the baffle plate 14 provided in the cylinder head cover 4 from the right side to the left side in the drawing. . Further, a communication passage 18 is formed so as to penetrate outward from the blowby gas main passage 17 toward the bulging wall portion 4a on the outer periphery of the cylinder head cover 4, and is introduced into the bulging wall portion 4a perpendicularly to the communication passage 18. A passage 20 is formed.
The lower end of the introduction passage 20 is an opening 21, and an enlarged large diameter portion 21 a is formed on the mating surface P of the lower end of the bulging wall portion 4 a of the opening 21. That is, the introduction passage 20 has a passage portion 20a through which blow-by gas flows and a large-diameter portion (widened) that is connected to the passage portion 20a with a step on the mating surface P side of the passage portion 20a and is wider than the passage portion 20a. Part) 21a.

On the other hand, the cylinder head 3 is configured as shown in a schematic plan view in FIG.
In the bulging wall portion 3 a on the outer periphery of the cylinder head 3, reflux passages 22 communicating with the introduction passages 20 of the cylinder head cover 4 are formed to penetrate in the vertical direction by the same number as the introduction passages 20. Is communicated with each intake port 10.
Above each intake port 10, an injection valve mounting portion 3c for mounting the injection valve is formed.
A mating surface P at the lower end of the bulging wall portion 4a of the cylinder head cover 4 is in contact with the upper surface of the bulging wall portion 3a of the cylinder head 3 with a gasket 23 constituting a seal member interposed therebetween as shown in FIG. It is attached.
The gasket 23 includes a seal portion 23a sandwiched between the mating surfaces P between the upper end of the bulging wall portion 3a of the cylinder head 3 and the lower end of the bulging wall portion 4a of the cylinder head cover 4, and an attachment projecting upward from the seal portion 23a. The mounting portion 23b of the gasket 23 is attached in contact with the inner periphery of the large diameter portion 21a formed in the opening 21 of the cylinder head cover 4.

An orifice member 24 is fitted into the inner periphery of the gasket mounting portion 23b, and the upper end side of the orifice member 24 is press-fitted into the passage portion 20a. A throttle portion 24a penetrating in the vertical direction is formed at the center of the orifice member 24, and the introduction passage 20 and the reflux passage 22 are communicated with each other via the throttle portion 24a.
A plug 19 is attached to the outer end of the communication path 18 and covered.

In such a structure, the blow-by gas flowing out from the gap between the cylinder bore 5 and the piston 6 passes through the cylinder head 3 and flows into the gas-liquid separator 16 of the cylinder head cover 4. A plurality of partitions are provided to form a detour, and the oil content of the blow-by gas is separated while passing through the gas-liquid separator 16.
The blow-by gas from which oil has been separated passes from the blow-by gas main passage 17 through the communication passage 18, passes through the throttle passage 24 a from the introduction passage 20, flows into the return passage 22, and is recirculated into each intake port 10. It is.
The flow rate of the blow-by gas passing therethrough can be adjusted by the throttle portion 24a of the orifice member 24, and the gasket mounting portion 23b is in contact with the outer periphery of the orifice member 24, and the upper end side of the orifice member 24 is a passage. Since it is press-fitted into the portion 20a, the displacement of the gasket 23 toward the introduction passage 20 is reliably prevented.

As described above, in the blowby gas recirculation structure of the present example, the orifice member 24 having the throttle portion 24 a is provided in the opening 21 of the introduction passage 20, and the gasket member 23 is brought into contact with the mounting portion 23 b of the gasket 23. Prevents misalignment. That is, the orifice member 24 is attached to the passage portion 20a with a gap between the orifice member 24 and the inner wall of the large diameter portion 21a, and the attachment portion 23b of the gasket 23 is inserted into the gap between the inner wall of the large diameter portion 21a. This prevents the displacement of the gasket 23.
In order to prevent the displacement of the gasket 23, it is necessary to provide wall portions that contact the mounting portion 23b on both sides of the introduction passage 20 side and the opposite side of the introduction passage 20 side. Of the wall portions for preventing the displacement, the wall portion on the introduction passage 20 side is substituted with the outer peripheral surface of the orifice member 24. That is, since the position of the wall portion on the introduction passage 20 side can be further provided on the introduction passage 20 side as compared with the position of the wall portion on the introduction passage 20 side in the structure having no conventional throttle portion, the cylinder head cover can be provided. 4 can be prevented from being increased in size and downsized.
In addition, the orifice member 24 is only press-fitted into the passage portion 20a, can be easily attached, and a compact structure can be secured.

Next, a second embodiment will be described with reference to FIGS.
The cylinder head cover 4 of the second embodiment has a structure as shown in a sectional view in FIG. That is, in the cylinder head cover 4, a fresh air introduction passage 15, a gas-liquid separator 16, and a blow-by gas main passage 17 are provided on the baffle plate 14, and the communication passage 18 passes through the blow-by gas main passage 17. An introduction passage 20 is formed in the bulging wall portion 4 a of the cylinder head cover 4 so as to be orthogonal to the communication passage 18.
The upper end side of the introduction passage 20 is penetrated and an opening 21 is formed on the mating surface P side on the lower end side. The opening 21 has a throttle portion 21b whose diameter is reduced in a tapered shape toward the mating surface P side. Are integrally formed. A mounting recess 21c having an opening on the mating surface P side is formed in a concave shape on the outer peripheral side of the throttle portion 21b. That is, the throttle portion 21b is formed as a reduced width portion that is connected to the passage portion 20a with a step on the mating surface P side of the passage portion 20a through which blow-by gas flows, and is narrower than the passage portion 20a.

FIG. 6 shows a state in which the cylinder head cover 4 is joined to the cylinder head 3, and plugs 19 and 19 a are provided at the outer end of the communication passage 18 and the upper end of the introduction passage 20, respectively. A gasket 23 is provided between the mating surface P on the lower end side of 21 and the upper end of the bulging wall portion 3a of the cylinder head.
The mounting portion 23b of the gasket 23 is fitted and mounted in the mounting recess 21c, and the seal portion 23a of the gasket 23 is sandwiched between the cylinder head cover 4 and the cylinder head 3.

  In such a structure, the mounting portion 23b of the gasket 23 is fitted into the mounting recess 21c formed on the mating surface P side of the lower end of the bulging wall portion 4a of the cylinder head cover 4, so that the gasket 23 may be displaced. In addition, the gasket 23 is prevented from being displaced with a compact structure, and the throttle portion 21b is formed integrally with the opening 21, so that no separate parts are required and the compactness is suppressed while suppressing an increase in the number of parts. It is planned.

  Also in this example, the blow-by gas flowing out from the gap between the cylinder bore 5 and the piston 6 is separated into oil by the gas-liquid separator 16, passed from the blow-by gas main passage 17 through the communication passage 18, and from the introduction passage 20 to the reflux passage 22. Thus, the flow rate of the blow-by gas recirculated to the intake port 10 side at the throttle portion 21b can be adjusted favorably.

  In each embodiment, the gas-liquid separator 16 is formed in the cylinder head cover 4, but the gas-liquid separator 16 may be provided as a gas-liquid separator separately from the cylinder head cover 4.

  As mentioned above, although embodiment of this invention was described using the Example, this invention is not limited to such an Example, In the range which does not deviate from the summary of this invention, it can implement with a various form. Of course.

It is a principal part longitudinal cross-section block diagram of an internal combustion engine. It is the expanded cross-section block diagram which expanded the principal part of FIG. It is a longitudinal cross-sectional block diagram of a cylinder head cover. It is a principal part enlarged view inside a cylinder head cover. It is a top view of a cylinder head. It is a principal part expanded longitudinal cross-section block diagram of the junction part of the cylinder head and cylinder head cover of 2nd Example. It is a longitudinal cross-section block diagram of the cylinder head cover of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder block 3 Cylinder head 3a Swelling wall part 4 Cylinder head cover 4a Swelling wall part (wall part)
5 Cylinder bore 6 Piston 7 Intake valve 10 Intake port 11 Intake manifold 16 Gas-liquid separation portion 17 Blow-by gas main passage 18 Communication passage 20 Introduction passage 20a Passage portion 21 Opening 21a Large diameter portion (widening portion)
21b Aperture part (reduced width part)
21c Mounting recess (recess)
22 Reflux passage 23 Gasket (seal member)
23a Seal part 23b Mounting part 24 Orifice member 24a Restriction part P Matching surface

Claims (5)

A blowby gas recirculation structure for recirculating blowby gas to the intake side,
A gas-liquid separation unit capable of separating oil in the blowby gas;
An introduction passage that is formed in the wall portion of the cylinder head cover so as to have an opening on a side that becomes a mating surface when the cylinder head cover is attached to the cylinder head, and into which the blow-by gas that has passed through the gas-liquid separation portion is introduced,
A recirculation passage formed in the cylinder head such that one end is connected to the introduction passage and the other end is connected to the intake port;
A seal member disposed on the mating surface and hermetically sealing the introduction passage and the return passage;
With
A blow-by gas recirculation structure in which a throttle portion is provided in the opening, and a part of the seal member is brought into contact with the throttle portion to prevent the seal member from being displaced toward the introduction passage. The introduction passage has a passage portion through which the blow-by gas flows, and a widened portion that is connected to the passage surface side of the passage portion with a step and is formed wider than the passage portion.
The throttle portion is formed by an orifice member attached to the passage portion in a state having a gap with the inner wall of the widened portion,
The blow-by gas recirculation structure according to claim 1, wherein the seal member is prevented from being displaced by inserting a part thereof into the gap. The throttle portion is formed as a reduced width portion that is connected to the passage portion with a step on the mating surface side of the passage portion through which the blow-by gas flows and is formed narrower than the passage portion.
A concave portion is formed on the outer periphery of the reduced width portion so as to surround the reduced width portion,
The blow-by gas recirculation structure according to claim 1, wherein the seal member is prevented from being displaced by inserting a part of the seal member into the recess.   The blow-by gas recirculation structure according to any one of claims 1 to 3, wherein the gas-liquid separator is formed in the head cover. An internal combustion engine in which the blowby gas flowing out from the gap between the piston and the cylinder bore is recirculated to the intake side by the blowby gas recirculation structure according to any one of claims 1 to 3.

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