JP4593393B2 - Arrangement structure of breather chamber in internal combustion engine - Google Patents

Description

  The present invention relates to an arrangement structure of a breather chamber in an internal combustion engine.

2. Description of the Related Art Conventionally, breather apparatuses that guide blow-by gas generated inside an internal combustion engine to a breather chamber provided above a cylinder head cover through a space between cylinder bores and discharge the blow-by gas to a reflux pipe connected to an intake passage are known.
In the breather device having such a structure, a breather chamber provided above the head cover is disposed so as to protrude above the head cover (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-188424 (page 7, FIG. 12)

  The breather device for an internal combustion engine described in Patent Document 1 is shown in FIG. 5. In this breather device, the blow-by gas in the crank chamber 01 of the internal combustion engine is sucked together with lubricating oil by a scavenge pump, and the mission chamber 02. The blow-by gas in the mission chamber 02 is discharged into the breather passage 04 formed in the space portion of the cylinder block 03 from the mission chamber 02, the breather passage 06 formed in the space portion of the cylinder head 05, and the upper portion of the cylinder head 05. The blow-by chamber is guided to the breather chamber 09 protruding from the head cover 08 through the rear valve chamber 07 and the like, and is further returned to the intake passage from the breather chamber 09 through a reflux pipe (not shown) and supplied to the combustion chamber for combustion. A gas reflux path is provided.

  The breather device has a breather chamber protruding above the head cover. For this reason, an increase in the size of the head cover is inevitable, and the overall height of the internal combustion engine must be increased. In addition, since the breather chamber protrudes from above the internal combustion engine, the breather chamber cools down, and water vapor in the breather chamber is likely to condense. There is a risk of inviting.

  In the situation as described above, the breather chamber, which has been conventionally arranged in the head cover, is arranged in the cylinder head so that the breather chamber does not protrude from above the engine, thereby avoiding cooling of the breather chamber. It is possible to provide an internal combustion engine with a reduced overall height by preventing problems such as the occurrence of condensation on the head cover, preventing the enlargement of the cover by arranging the breather chamber on the head cover, and making the cylinder part compact. To do.

The present invention relates to an arrangement structure of a breather chamber in an internal combustion engine for solving the above-mentioned problems, and the invention according to claim 1 relates to a plurality of cylinders (CR) in which pistons (P) slide are separated. The cylinder block (1) arranged in parallel and the cylinder head (2R) coupled to the cylinder block, the breather chamber (1R1) is provided in the cylinder block (1). The cylinder head (2R) is formed integrally with a cylinder block, and another breather chamber (2R1) communicating with the breather chamber (1R1) of the cylinder block (1) is formed. 2R1) breather pipe for discharging blow-by gas to the outside in (2a) is disposed between the intake port (23) or an exhaust port of the cylinder head (2R) (25), sent to Shi cylinder head (2R) lubricating oil return oil to return to the oil pan (4), the cylinder The return oil passage (2R2, 1R2) is formed in the area between the cylinder bore (BR) of the cylinder block (1R) and the cylinder block (1), and the breather chambers (1R1, 2R1) are areas between the cylinder bores (BR). The return oil passages (2R2, 1R2) are arranged adjacent to each other in parallel with a partition wall (2R3, 1R3) therebetween, and the blow-by gas in both breather chambers is warmed by the return oil in the return oil passages. This is an arrangement structure of a breather chamber in an internal combustion engine characterized by being configured as described above.

According to a second aspect of the present invention, in the arrangement structure of the breather chamber in the internal combustion engine according to the first aspect, the internal combustion engine includes a first bank (1F, 2F) and a second bank each composed of a plurality of cylinders (CR). A V-type internal combustion engine in which two banks (1R, 2R) are arranged in a V shape, the cylinder bore interval of one bank and the cylinder bore interval of the other bank are different, and the breather chambers (1R1, 2R1 ) Are arranged in banks (1R, 2R) having a large cylinder bore interval .

The invention according to claim 3 is the arrangement structure of the breather chamber in the internal combustion engine according to claim 2, wherein the first bank (1F, 2F) and the second bank (1R, 2R) are a front bank and a rear bank. The breather pipe (2a) protrudes obliquely upward toward the rear wall portion of the cylinder head (2R) of the second bank (1R, 2R).

According to a fourth aspect of the present invention, in the arrangement structure of the breather chamber in the internal combustion engine according to the second aspect, the breather pipe (2a) has a recessed return oil passage opening in the deck upper surface (2R4) of the cylinder head (2R). (2R20) is provided.

In the invention according to claim 1 of the present invention, the breather chamber is formed between the cylinder bores of the cylinder block, and the breather chamber is also formed in the cylinder head so as to communicate with the breather chamber. It does not protrude upward, and the cylinder head height can be kept from becoming high, and the breather chamber is positioned in the vicinity of the cylinder bore, so that the breather chamber is warmed and water vapor condensation is suppressed. Deterioration of lubricating oil due to mixing can be prevented. Moreover, the capacity | capacitance of a breather chamber can be ensured corresponding to various internal combustion engines, and a breather chamber can be arrange | positioned using the dead space produced between cylinder bores.
In addition, since the breather pipe that discharges the blow-by gas in the breather chamber to the outside is arranged between the intake port or the exhaust port of the cylinder head, the cylinder head height is lower than when the breather pipe is arranged above the cylinder head cover. Can be suppressed.
Further, a double breather chamber, and a return oil passage for returning the lubricating oil sent cylinder head to the oil pan, the area between the cylinder bores, be located adjacent in parallel form to Riaburaro back at a partition wall As a result, the breather chamber can be warmed by the lubricating oil passing through the cylinder bore and the return oil passage, so that condensation of water vapor in the breather chamber can be further suppressed.

In the invention according to claim 2, in the V-type internal combustion engine in which a plurality of cylinders are arranged in each bank, the breather chamber can be arranged by utilizing the space between the cylinder bores that tend to be a dead space.

An embodiment of the present invention will be described with reference to FIGS.
Referring to FIG. 1, a main structure of a V-type internal combustion engine E to which the present invention is applied is shown in a side sectional view.
The V-type internal combustion engine E is a DOHC-type, water-cooled V-type 5-cylinder 4-cycle internal combustion engine, and constitutes a power unit mounted on a motorcycle (not shown) together with a transmission that transmits the power to the rear wheels.

  As shown in FIG. 1, the internal combustion engine E includes a front bank 1F and a rear bank 1R that form a V-shaped V bank having an angle of approximately 75 ° in the front-rear direction in a side view, and a lower portion of the front bank 1F. The cylinder block 1 forming the upper case 1A of the crankcase 1C, the front cylinder head 2F and the rear cylinder head 2R mounted on the banks 1F and 1R above and behind the cylinder block 1, respectively, the front cylinder head 2F and the rear cylinder A front head cover 3F and a rear head cover 3R attached to the respective upper portions of the head 2R, and a lower crankcase fastened to the block 1 with its upper end surface 1B1 aligned with the lower end surface 1A1 of the upper crankcase 1A of the cylinder block 1 1B is provided as its basic structure.

  A crankshaft 5 is disposed in the crankcase 1C so as to be laterally oriented in the left-right direction of the vehicle body. The crankshaft 5 includes a lower end surface 1A1 of the upper crankcase 1A and an upper end surface 1B1 of the lower crankcase 1B. The rotation axis L is positioned on the mating surfaces of the two crankshafts and is rotatably supported in the crankcase 1C including the upper crankcase 1A and the lower crankcase 1B.

  A crank chamber 1C1 is formed by the front portion of the upper crankcase 1A and the front portion of the lower crankcase 1B. The crankshaft 5 is accommodated in the crank chamber 1C1, and the rear portion and the lower crankcase of the upper crankcase 1A are accommodated. A mission chamber 1C2 is formed by the rear portion of 1B, and a wet multi-plate friction clutch and a constantly meshing gear transmission which are not shown in the figure and constitute a transmission device are accommodated in the mission chamber 1C2. An oil pan 4 is fastened to the lower end surface 1B2 of the lower crankcase 1B with its upper end surface 4a being oil-tightly fitted to the case 1B.

  Although not clearly illustrated in FIG. 1, the front bank 1F has three cylinders CF arranged along the rotation axis L direction of the crankshaft 5 and integrally coupled, and is formed in each cylinder. The center line NF of the cylinder bore BF is directed forward and obliquely upward from the rotation axis L, and each cylinder CF is inclined forward.

  Further, the rear bank 1R has two cylinders CR that are arranged along the rotation axis L direction and are integrally coupled, and the center line NR of the cylinder bore BR formed in each cylinder is obliquely rearward from the rotation axis L. The cylinders CR are tilted backwards in the upward direction. Pistons P are slidably fitted to the cylinder bores BF, BR of the cylinders CF, CR, and reciprocate by the combustion pressure in the combustion chamber 21 formed between the pistons P and the cylinder heads 2F, 2R. P rotates the crankshaft 5 via a connecting rod R that connects each piston P and the crankshaft 5.

  As described above, the front bank 1F of the cylinder block 1 is provided with three cylinder bores BF, and the rear bank 1R is provided with two cylinder bores BR. Compared with the front bank 1F provided with three cylinder bores, the rear bank 1R has more space between the cylinder bores BR, and the lower part communicates with the mission chamber 1C2 between the two cylinder bores BR of the rear bank 1R. Is provided with a breather chamber 1R1 which is a space for passage of blow-by gas communicating with a later-described breather chamber 2R1 of the cylinder head 2R.

  The breather chamber 1R1 is provided near the rear of the bank 1R between the cylinder bores BR, that is, on the exhaust side. The breather chamber 1R1, which is the space, is arranged in parallel with this and separated adjacent to the partition wall 1R3. An oil return oil passage 1R2 is provided. The details of the structure of the breather chamber 1R1 and the return oil passage 1R2 will be described later.

  Gaskets G, which will be described later, are interposed between the upper portions of the front and rear banks 1F and 1R of the cylinder block 1, and the lower portions of the front and rear cylinder heads 2F and 2R are joined and attached. Each cylinder head 2F, 2R has a pair of intake ports 22 that open to the combustion chamber 21 for each combustion chamber 21, as can be understood from reference to FIG. 3 and FIG. And an exhaust port 25 having a pair of exhaust ports 24, a pair of intake valves 22a for opening and closing the pair of intake ports 22, and a pair of exhaust ports 24 for opening and closing the pair of exhaust ports 24, respectively. A pair of exhaust valves 24 a are provided, and spark plugs (not clearly shown) facing each combustion chamber 21 are provided.

  As shown in FIGS. 3 and 4, the cylinder head 2 </ b> R above the rear bank 1 </ b> R of the cylinder block 1 is disposed between the two combustion chambers 21 and closer to the rear of the head 2 </ b> R, that is, on the exhaust side, as illustrated in FIGS. A space for the breather chamber 2R1 communicating with the breather chamber 1R1, which is the above-described space for blow-by gas passage formed in the rear bank 1R, is arranged adjacent to and parallel to this space with a partition wall 2R3 therebetween. A return oil passage 2R2 for the lubricating oil is formed. Details of the structure of the breather chamber 2R1 and the return oil passage 2R2 will be described later.

  As shown in FIG. 1, an intake cam shaft 10 and an exhaust cam shaft 11 are respectively synchronously driven on the upper portions of the front and rear cylinder heads 2F and 2R via a drive mechanism (not shown) at one end of the shaft. It is mounted so as to be rotatable about its rotation axis L. The intake camshaft 10 and the exhaust camshaft 11 disposed above the front and rear cylinder heads 2F and 2R are disposed in parallel to each other with their rotational axes L separated by a predetermined distance, and these camshafts 10 and 11 are arranged at a plurality of axial positions. The journal portions are supported by cam holders each comprising a bearing, so that the journal portions are rotatably supported with respect to the front and rear cylinder heads 2F and 2R.

  The camshafts 10 and 11 mounted on the upper portions of the front and rear cylinder heads 2F and 2R are driven at a rotational speed 1/2 that of the crankshaft 5 by the power of the crankshaft 5 through a transmission mechanism that is not clearly shown. The rotation of the camshafts 10 and 11 drives the intake valves 22a and the exhaust valves 24a for opening and closing operations at a predetermined timing.

  An intake device connected to each intake port 23 is disposed inside a V bank including front and rear banks 1F and 1R, and an exhaust pipe (not shown) connected to the exhaust port 25 of the cylinder CF of the front bank 1F is an oil pan. 4 extends backward through the space near the lower wall.

  As described above, the upper surfaces of the front and rear cylinder heads 2F and 2R are covered with the head covers 3F and 3R. The head covers 3F and 3R, as can be understood from reference to FIGS. The upper surface (planar) has a shape like a rectangular fold, and includes upper surface portions 3F1 and 3R1 and side surface portions 3F2 and 3R2 depending from the upper surface portions 3F1 and 3R1.

  The head cover upper surface portions 3F1 and 3R1 do not completely cover the upper surface portions of the cylinder heads 2F and 2R, but are lifters at the upper portions of the two camshafts 10 and 11 and the stem upper ends of the intake valves 22a and the exhaust valves 24a. However, it does not cover the upper part of the mounting hole of the spark plug.

  The head covers 3F and 3R are attached to the cylinder heads 2F and 2R, as shown in FIGS. 1 and 4 and the like, as shown in FIGS. The lower edges 3F3 and 3R3 of 3F2 and 3R2 are inserted and fixed.

Referring to FIG. 1, an oil strainer 41 is disposed in the oil pan 4, and an oil pipe 42 extending upward from the oil strainer 41 is connected to a suction port (not shown) of the feed pump Pf of the oil pump unit U. Is done. The oil pump unit U includes a scavenge pump Ps and a feed pump Pf arranged in the axial direction of the drive shaft U1.
The pump unit U is provided in an inclined partition wall 1B3 that is slightly inclined slightly above the lower end surface 1B2 of the crankcase.

  The inclined partition wall 1B3 is provided with suction ports 1B4 respectively connected to the suction port Ps1 of the scavenge pump Ps. The suction ports 1B4 are supplied into the crank chamber 1C1 and lubricate the required lubrication points to the bottom of the crank chamber 1C1. The lubricating oil that has flowed down is sucked from the suction port 1B4 to the scavenge pump Ps through the suction port Ps1, and the sucked lubricating oil extends into the mission chamber 1C2 connected to the discharge port Ps2 of the scavenge pump Ps. The oil is discharged into the mission chamber 1C2 from the discharge port L3o at the upper end of the oil passage L3 reaching the gear group of the main shaft or counter shaft gear transmission (not shown) directed upward.

  As described above, the suction port of the feed pump Pf is connected to the oil pipe 42 extending above the oil strainer 41, the discharge port is connected to the oil passage L1, and further from the oil passage L1 through the oil filter Of and the oil cooler Oc. Supplies lubricating oil to the main gallery L2 extending substantially horizontally along the valleys of both the front bank 1F and the rear bank 1R of the upper crankcase 1A and extending over substantially the entire length of the valleys. The lubricating oil is supplied to the in-shaft oil passage of the crankshaft 5 and to the valve mechanisms of the cylinder heads 2F and 2R through an oil passage (not shown).

  The lubricating oil supplied to the lubricating parts through the lubricating oil paths described above then flows down to the bottom of the crank chamber 1C1, or flows down to the bottom of the oil pan 4 below the lower crankcase 1B through the mission chamber 1C2, etc. It is circulated and supplied to each lubricating part by the pump Ps or by the feed pump Pf.

  As described above, the return oil of the lubricating oil used for lubricating each part flows down to the bottom of the crank chamber 1C1 or from the mission chamber 1C2 into the oil pan 4. Then, the return oil on the rear bank 1R side, that is, the lubricating oil on the deck upper surface 2R4 of the cylinder head 2R used for lubrication of the valve operating mechanism flows smoothly without staying on the deck upper surface 2R4.

  Although not shown in the figure, the cylinder head 2R is in the lower part of the space for extending the two cam shafts 10 and 11 in the top view and between the spaces corresponding to the two cylinder bores BR, and the deck upper surface 2R4 of the head 2R. The two openings 2R20 of the oil passage 2R2 for returning oil are provided so as to sandwich the opening 2R10 of the breather device to be described later (see FIG. 4).

  Referring to FIG. 4, the periphery of these openings 2R20 is recessed in order to make it easier for lubricating oil used for lubrication of the valve operating mechanism or the like to flow into the two openings 2R20 of the return oil passage 2R2 on the deck upper surface 2R4 of the cylinder head 2R. Although not understood from FIG. 4, the shape of the two openings 2R20 of the return oil passage 2R2 in a top view is a long and narrow shape in the longitudinal direction of the deck upper surface 2R4 of the cylinder head 2R (FIG. 3). The opening near the center of the deck upper surface 2R4 of the head 2R has a substantially crescent shape, and the opening near the rear has a slightly wide slit shape. These openings are gathered together as a single oil passage 2R2 in the space immediately below the opening (see FIG. 4).

  Further, the rear bank 1R of the cylinder block 1 is provided with an opening 1R20 of the return oil passage 1R2 between the two cylinder bores BR and at a position closer to the rear of the bank 1R (see FIG. 2). It is vertically aligned with a lower opening 2R21 (see FIGS. 3 and 4) of an oil passage 2R2 for return oil provided in the head 2R, and there is an opening of a gasket G to be described later. A return oil passage that passes through the openings 1R21 below the bank 1R of the cylinder block 1 is formed from the two openings 2R20 on the deck upper surface 2R4, and the lower portion of the return oil passage is above the crank chamber 1C1 through the opening 1R21. Communicating with

  The oil passage opening 1R20 for the return oil in the rear bank 1R of the cylinder block 1 has a long slit shape in the top view of the bank 1R, that is, the inlet opening 1R20 of the return oil passage 1R2 in the rear bank 1R. However, the oil passage 1R2 directly below the inlet opening 1R20 is formed as a structure in which the oil passage area in a cross section having a substantially rectangular shape with an approximately length and width antagonized is enlarged, although not clearly illustrated.

  Further, the rear bank 1R of the cylinder block 1 and the cylinder head 2R on the upper side thereof are provided with breather chambers 1R1 and 2R1 of a breather device for discharging blow-by gas over both of them. Then, as shown in FIG. 4, two long and narrow openings for the return oil at the substantially central part of the deck upper surface 2R4 of the cylinder head 2R on the rear bank 1R and the rear side, that is, a crescent shape and a little. An opening 2R10 for the breather chamber 2R1 is formed adjacent to the two openings 2R20 in parallel with the two openings 2R20 having a wide slit shape and in the front-rear direction of the deck upper surface 2R4 of the head 2R. Is provided.

  Referring to FIG. 4, one end of a breather pipe 2a of a breather device made of a cylindrical body having a predetermined length, that is, a lower end 2a1 is fitted and fixed to the opening 2R10, and the other end of the breather pipe 2a is a cylinder. A rear wall portion of the head 2R, that is, a projecting portion 2a2 that projects obliquely upward from the wall portion between the two exhaust ports 25 of the rear wall portion of the cylinder head 2R and projects outward by a predetermined length. 2a3 is fastened and fixed to the wall portion by bolts B via attachment portions 2a4 for further strengthening the attachment. The attachment position of the breather pipe 2a can be selected as a structure protruding from the wall portion between the intake ports 23 by a design change within a range not departing from the gist of the present invention.

  An opening 2R10 for the breather device on the deck upper surface 2R4 of the rear cylinder head 2R is provided in parallel with and adjacent to the oil passage opening 2R20 at a position sandwiched between the two oil passage openings 2R20 for return oil. The space for the breather chamber 2R1, which extends downwardly from the opening 2R10, is also adjacent to each other in parallel with the oil passage 2R2 for return oil across the partition wall 2R3 (see FIG. 4).

  Referring to FIG. 2, an opening 1R10 for breather chamber 1R1 in rear bank 1R of cylinder block 1 is aligned with a lower opening 2R11 for breather chamber 2R1 in cylinder head 2R at its upper and lower positions, and returns oil. Parallel to the oil passage opening 1R20 and adjacent to each other across the partition wall 1R3, the opening 1R11 below the breather chamber 1R1 communicates with the upper opening of the mission chamber 1C2.

  An arrangement structure in which the rear cylinder head 2R and the breather chambers 2R1 and 1R1 in the rear bank 1R of the cylinder block 1 are separated from the partition walls 2R3 and 1R3 of the oil passages 2R2 and 1R2 for return oil in parallel and adjacent to each other is a breather chamber. Since the blow-by gas of 1R1 and 2R1 is indirectly warmed by the relatively high temperature lubricating oil that is the return oil, it contributes in suppressing the condensation of water vapor in the breather chambers 1R1 and 2R1.

  As described above, the gasket G is interposed between the joint surfaces of the lower surface of the cylinder head 2R and the upper surface of the rear bank 1R of the cylinder block 1. In the gasket G, the openings 1R20 and 2R21 of the above-described return passages 1R20 and 2R2 and the openings of the breather chambers 1R1 and 2R1 for the above-described return oil, which are the alignment positions of the cylinder head 2R and the rear bank 1R of the cylinder block 1, are provided. Positionally aligned openings for allowing 1R10 and 2R11 to communicate with each other without hindrance are formed in parallel and adjacent to each other.

  The gasket G is composed of three sheets, and is a hole penetrating the three-layered plate for communication between the breather chambers 1R1 and 2R1 and for communication of the oil passages 1R2 and 2R2 for return oil. The center part of the plate is a through hole in the front and back plate parts of the three layers, but the center plate sandwiched between the front and back plates is a board in which no hole is formed. Therefore, this substantially central part forms a through hole. The substantially central portion not penetrating prevents the blow-by gas from coming up from the central space 1C3 of the rear bank 1R of the cylinder block 1 shown in FIG.

  The return oil used for lubrication of the valve mechanism on the upper surface of the cylinder head 2F on the front bank 1F side flows through the oil passage opening according to the same selection as that on the rear bank 1R side, and therefore returns. The oil passage opening for oil extends between the appropriate two spaces above the combustion chamber 21 of the three cylinder bores BF on the upper surface of the cylinder head 2F and the cam shafts 10 and 11 at positions closer to the rear of the head 2F. The position facing the lower part of the space is selected as appropriate, but the arrangement of the oil passage openings for the return oil in the front bank 1F is naturally limited by the presence of the three cylinder bores. The periphery of the oil passage opening is recessed to facilitate smooth flow of return oil.

  The oil passage for the return oil passes through the head 2F from the oil passage opening on the upper surface of the cylinder head 2F deck and reaches the opening at the bottom of the oil passage. The front bank 1F is provided with a return oil passage that is aligned with the oil passage opening of the cylinder head 2F at the upper and lower positions, and the oil passage opening below the front bank 1F opens at the top of the crank chamber 1C1. An oil passage space for the breather chamber is not provided on the front bank 1F side. Between the upper surface of the front bank 1F and the lower surface of the cylinder head 2F, a gasket G having an opening aligned for return oil is interposed.

  Since this invention is provided with the structure mentioned above, there exist the following effects.

  That is, the breather chambers 1R1 and 2R1 are arranged in parallel and adjacent to the return oil passages 1R2 and 2R2 of the lubricating oil with the partition walls 1R3 and 2R3 therebetween, so that the blow-by gas in the breather chambers 1R1 and 2R1 has a relatively high temperature. The high return oil and the partition walls 1R3 and 2R3 are indirectly heated, so that condensation of water vapor in the breather chambers 1R1 and 2R1 is prevented, and moisture and gasoline contained in the blow-by gas are left outside the engine E as they are. Dilution and deterioration of the lubricating oil due to drainage and mixing of water droplets is avoided. Further, since the breather chambers 1R1 and 2R1 are formed in the vicinity of the cylinder bore BR, they are also affected by heat from the cylinder bore BR, so that the effect of preventing condensation is further improved.

  Since the breather chambers 1R1 and 2R1 are provided across the cylinder block 1 and the cylinder head 2, the height of the cylinder head 2 can be suppressed lower than that of the conventional head cover 3 provided with the breather chamber. The increase in size of the cylinder portion is avoided, and as a result, the internal combustion engine E can be reduced in size. Further, by providing the breather chambers 1R1 and 2R1 across the cylinder block 1 and the cylinder head 2, it is possible to ensure the capacity of the breather chamber corresponding to various internal combustion engines.

  The breather chambers 1R1, 2R1 and the lubricating oil return oil passages 1R2, 2R2 from the cylinder head 2R are arranged between the cylinder bores BR and parallel to a plane including a plurality of cylinder central axes, and the breather chambers 1R1, 2R1 And the lubricating oil return oil passages 1R2 and 2R2 are disposed adjacent to each other. Therefore, the breather chambers 1R1 and 2R1 and the lubricating oil return oil passages 1R2 and 2R2 are collectively arranged between the cylinder bores BR. The return oil passages 1R2 and 2R2 can be made compact.

  In a parallel internal combustion engine in which cylinder blocks are separated from each other, a breather chamber can be arranged by utilizing a dead space generated between cylinder bores.

  Since the breather pipe, which is the discharge pipe of the breather device, is arranged between the intake port or the exhaust port of the cylinder head, the height of the cylinder head can be suppressed lower than when the discharge pipe is arranged above the head cover. It is possible to reduce the size of the engine.

  In a V-type internal combustion engine in which a plurality of cylinders are arranged in each bank, the breather chamber can be arranged by utilizing the space between cylinder bores that tend to be dead spaces.

It is a figure of the principal side cross section of the V-type internal combustion engine to which this invention is applied. It is side sectional drawing of the cylinder block of this invention. It is a bottom view of the back cylinder head of the present invention. It is a sectional side view of the principal part of the back cylinder head of the present invention. It is a figure which shows the breather apparatus in the conventional internal combustion engine.

Explanation of symbols

1. ・ Cylinder block, 1A ... Upper crankcase, 1B ... Lower crankcase, 1F ... Front bank, 1R ... Rear bank, 1R1,2R1 ... Breaser chamber, 1R2,2R2 ...・ Return oil path, 2F ... front cylinder head, 2R ... rear cylinder head, 3F ... front head cover, 3R ... rear head cover, 4 ... oil pan, 5 ... crankshaft .

Claims (4)

An internal combustion engine comprising a cylinder block (1) in which a plurality of cylinders (CR) on which pistons (P) slide are spaced apart and arranged in parallel, and a cylinder head (2R) coupled to the cylinder block. ,
In the cylinder block (1), a breather chamber (1R1) is formed integrally with the cylinder block,
The cylinder head (2R) is formed with another breather chamber (2R1) communicating with the breather chamber (1R1) of the cylinder block (1).
The breather pipe (2a) for discharging the blow-by gas in both the breather chambers (1R1, 2R1) to the outside is disposed between the intake port (23) or the exhaust port (25) of the cylinder head (2R),
Shi cylinder head (2R) to sent the lubricating oil return oil to return to the oil pan (4), the oil passage to return to the area between the cylinder bore (BR) of the cylinder head (2R) and the cylinder block (1) ( 2R2, 1R2) is formed, and both breather chambers (1R1, 2R1) are arranged in parallel with the return oil passage (2R2, 1R2) with a partition wall (2R3, 1R3) in the region between the cylinder bores (BR). An arrangement structure of a breather chamber in an internal combustion engine, wherein the blow-by gas in both breather chambers is warmed by the return oil in the return oil passage .   The internal combustion engine is a V-type internal combustion engine in which a first bank (1F, 2F) and a second bank (1R, 2R) each composed of a plurality of cylinders (CR) are arranged in a V shape, The cylinder bore interval of one bank is different from the cylinder bore interval of the other bank, and the breather chamber (1R1, 2R1) is arranged in a bank (1R, 2R) having a large cylinder bore interval. The arrangement structure of the breather chamber in the internal combustion engine described.   The first bank (1F, 2F) and the second bank (1R, 2R) are the front bank and the rear bank, and the breather tube (2a) is the cylinder head (2R) of the second bank (1R, 2R). The arrangement structure of the breather chamber in the internal combustion engine according to claim 2, wherein the rear wall portion projects obliquely upward.   3. A breather chamber in an internal combustion engine according to claim 2, wherein the breather pipe (2a) is provided in a recessed return oil passage opening (2R20) of a deck upper surface (2R4) of the cylinder head (2R). Placement structure.

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