JPH053692Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a flat engine installed so that the cylinder axis is approximately horizontal, that is, at an angle of inclination that is either horizontal or close to horizontal. This invention relates to a flat engine that is provided with a breather passage that communicates between the engine and the cam chamber.

(Prior art) Flat engines are often used as automobile engines (for example, the
(Refer to Publication No. 88018). A flat engine is installed so that the cylinder axis is horizontal or at an angle of up to 30° from the horizontal plane, the crankshaft is perpendicular to the longitudinal direction of the vehicle, and the cylinder head is oriented perpendicular to the forward direction. It is mounted on the vehicle body so that it is located at the rear. Therefore, since the engine is relatively flat, the height of the engine room can be reduced.

Incidentally, in automobile engines, in order to ventilate the cam chamber provided inside the cylinder head and the crank chamber provided at the end of the cylinder block, a breather passage is provided to communicate the cam chamber and the crank chamber. In addition, a crankcase ventilation (PCV) system is used to return blow-by gas from the crank chamber to the engine's intake system. In that case,
The breather passage is usually located inside the cylinder block.

The engine also needs to be provided with an oil return passage that returns the oil accumulated in the cam chamber to the oil pan. The oil return passage is also normally provided inside the cylinder block.

Therefore, even in the flat engine as described above, it is necessary to provide a breather passage and an oil return passage in the cylinder block. Therefore, it has been considered to make these breather passages and oil return passages common, so that they serve the same purpose.

(Problems to be Solved by the Invention) However, in such an engine, normally air flows from the crank chamber to the cam chamber, and oil flows from the cam chamber to the oil pan on the crank chamber side. In other words, these air and oil move in opposite directions. Moreover, at high engine speeds,
The flow rate of air increases, and a large amount of oil circulates, so the amount of oil returned also increases. Therefore, when the breather passage and the oil return passage are shared, the passage must be cut off in order to prevent the flow of air and oil from interfering with each other. This requires a very large area.

Additionally, the oil in the cam chamber generally returns to the oil pan by gravity. For this reason, in a flat engine like the one mentioned above,
The oil return passage must be provided on the bottom side of the cylinder block. Therefore, when a flat engine is designed to serve both as a breather passage and an oil return passage, an extremely large diameter passage is provided on the lower surface of the cylinder block.

If such a large diameter passage is provided on one side of the cylinder block, sufficient rigidity and sealing performance of the cylinder head clamping surface cannot be obtained.

Therefore, in a flat engine, it is conceivable to separate the breather passage and the oil return passage. In that case, a swirling wind is generated in the crank chamber due to the rotation of the crankshaft, and the swirling wind becomes especially strong when the engine rotates at high speeds. A large amount of air must be delivered to the Moreover, it is desirable to reduce the amount of oil mist contained in the air as much as possible.

The present invention was developed in view of these circumstances. The purpose of this is to ensure that sufficient air is sent from the crank chamber to the cam chamber and that oil in the cam chamber is reliably returned to the oil pan even when the flat engine rotates at high speeds.

(Means for Solving the Problem) In order to achieve this object, the present invention provides an oil return passage on the bottom side of the cylinder block of a flat engine, and a breather passage on the top side of the cylinder block. The breather passage and the oil pan in the lower part of the crank chamber are communicated with each other by a vertical journal through hole provided in the crank journal wall.

(Function) With this configuration, the breather passage and the oil return passage are provided separately and far apart on the upper and lower sides of the cylinder block, so that the air flowing from the crank chamber to the cam chamber and the cam The oil flowing from the chamber to the crank chamber side no longer interferes with each other. The breather passage communicates directly with the crank chamber as well as through the journal through-hole, so no matter which direction the swirling wind in the crank chamber is caused by the rotation of the crankshaft, it can be reliably controlled. Air in the crank chamber is now sent to the cam chamber.

(Example) Hereinafter, an example of the present invention will be described using the drawings.

The figures show an embodiment of a flat engine according to the present invention, with FIG. 1 being a longitudinal sectional side view thereof, and FIG. 2 being a cutaway plan view of the main parts thereof.

As is clear from these figures, the flat engine 1 is an in-line four-cylinder engine, and the cylinder block 2 includes four cylinders 3 1 , 3 ₁ ,
3 ₂ , 3 ₃ , and 3 ₄ (number 3 is used to represent these) are arranged in series. As shown in FIG. 1, the cylinder block 2 is installed so that the axis LL of the engine 3 is approximately horizontal, that is, it is horizontal or has an inclination angle of up to about 30° from the horizontal plane. ing.

A cylinder head 4 is attached to the rear end face of the cylinder block 2. This cylinder head 4 is provided with combustion chambers 5 at positions facing each of the engines 3, and an air-fuel mixture is introduced through an intake port 7 opened and closed by an intake valve 6, while exhaust gas is discharged through an exhaust port 9 opened and closed by an exhaust valve 8. A cam chamber 11 covered by a cylinder head cover 10 is provided inside the cylinder head 4, and a valve mechanism 12 for operating the intake valves 6 and exhaust valves 8 is provided inside the cam chamber 11.

The front end 13 of the cylinder block 2 is widened, and a crankcase 14 is attached to the front end surface thereof. In this way, a crank chamber 15 is formed by the front end portion 13 of the cylinder block 2 and the crank case 14. Inside the crank chamber 15, a crankshaft 17 is rotatably driven by a piston 16 sliding inside the engine 3.
is provided. This crankshaft 17 includes crank journal walls 18 ₁ to 18 ₅ integrally provided within the front end 13 of the cylinder block 2 and bearing caps 19, 19, . . . assembled thereto.
It is designed to be rotatably supported. The rotational direction of the crankshaft 17 is restricted to the counterclockwise direction shown by arrow R in FIG.

An oil pan 20 for storing engine lubricating oil is attached to the lower part of the crank chamber 15, that is, the front end 13 of the cylinder block 2 and the lower part of the crankcase 14. This oil pan 20
is configured to have a large opening with respect to the crank chamber 15.

The crank journal walls 18 ₁ and 18 ₅ at both ends are
The cylinder block 2 is connected to the left and right end walls of the cylinder block 2, respectively. Further, the intermediate crank journal walls 18 ₂ , 18 ₃ , 18 ₄ are connected to partition walls 21 ₂ , 21 ₃ , 21 ₄ between the cylinders 3 ₁ to 3 ₄ , respectively.

Endmost cylinder 3 ₁ and second cylinder 3 ₂
A breather passage 22 is provided in a portion of the partition wall 21 ₂ between the cylinder block 2 and the crank journal wall 18 ₂ that is connected to the partition wall 21 2 on the upper surface side of the cylinder block 2 . One end of this breather passage 22 is open to the front end surface of the crank journal wall 18 ₂ .
It communicates directly with the crank chamber 15 through the opening 22a. The other end opens at the rear end surface of the cylinder block 2, that is, the cylinder head clamping surface, and communicates with the cam chamber 11 via a passage (not shown) provided in the cylinder head 4. In this way, the cam chamber 11 and the crank chamber 15 communicate with each other through the breather passage 22.

Furthermore, on the crank journal wall 18 ₂ ,
A journal through hole 23 is provided that passes through it vertically. The through hole 23 is substantially perpendicular to the cylinder axis LL, and its upper and lower ends are opened to the upper and lower surfaces of the cylinder block 2, respectively. Therefore, the above-mentioned breather passage 22 intersects with this through hole 23 and also communicates with the oil pan 20 through the through hole 23. The through hole 23 is formed by casting when the cylinder block 2 is cast, and the middle part has a smaller cross-sectional area than both the upper and lower ends, so that the middle part has a narrowed part 23a.
is beginning to form. The upper end of the through hole 23 is widened to the central crank journal wall ₁₈₃ , thereby forming a breather chamber 24.

The central crank journal wall ₁₈₃ is provided with an oil hole 25 passing through it vertically. This oil hole 25 is formed by machining and has a relatively small diameter. The upper end of the oil hole 25 opens at the lower part of the breather chamber 24, and the lower end opens toward the oil pan 20.

A PCV valve 26 is provided on the upper end surface of the journal through hole 23, that is, on the upper surface of the breather chamber 24.
is installed. Then, this PCV valve 26 and the intake manifold 27 of the engine 1,
They are connected by a PCV tube 28.

The partition wall 21 ₂ between the cylinders 3 ₁ and 3 ₂ further includes:
An oil return passage 29 is provided on the lower surface side of the cylinder block 2. One end of this oil return passage 29 opens at the lower end of the journal through hole 23, thereby communicating with the oil pan 20. The other end opens at the cylinder head clamping surface on the rear end surface of the cylinder block 2 and communicates with the lower end of the cam chamber 11 via a passage (not shown) provided in the cylinder head 4. ing. In this way, the oil accumulated in the cam chamber 11 is returned to the oil pan 20 through the oil return passage 29.

Although not shown, the cam chamber 11 is also connected to an air cleaner through a breather tube.

Next, the operation of the flat engine 1 configured as described above will be explained.

When the engine 1 rotates, the crankshaft 17 rotates in the direction of arrow R in FIG. Therefore, a swirling wind in the direction of arrow R is generated in the crank chamber 15.

In this case, the higher the engine speed, the stronger the swirling wind. Therefore, the blow-by gas in the crank chamber 15 that attempts to flow into the breather passage 22 from the opening _22a formed in the upper part of the front end surface of the crank journal wall 182 is resisted by the swirling wind. However, since the breather passage 22 also communicates with the crank chamber 15 through the journal through-hole 23, at this time, the blow-by gas flows from the lower end of the through-hole 23, and the breather passage 22 from the upper end.
2 into the cam chamber 11. At this time,
The blow-by gas flowing from the lower end side of the journal through-hole 23 contains a large amount of oil mist.
a is provided so that the flow velocity is sufficiently reduced in the breather chamber 24 on the upper end side, so that the oil mist is easily separated by the breather chamber 24.

In this way, when the engine 1 rotates at high speed, air with less oil mist is sufficiently sent to the cam chamber 11 through the breather passage 22.

The oil separated by Breather Chamber 24 is
The oil also tries to flow down through the journal through-hole 23, but at this time, since a large amount of air is flowing upward through the through-hole 23, the flow of the oil is likely to be obstructed. Therefore, at this time, the oil is mainly returned to the oil pan 20 through the oil hole 25 provided in the central crank journal wall ₁₈₃ .

Further, when the engine 1 rotates at a high speed, the oil pump rotates at a high speed, and a large amount of oil is supplied to various parts to be lubricated, such as the valve mechanism 12. The oil that has lubricated the valve mechanism 12 naturally falls and accumulates at the lower end of the cam chamber 11, and then flows through the oil return passage 29 provided on the lower surface of the cylinder block 2 to the crank chamber 1.
Flows to the 5th side. And journal through hole 23
is returned to the oil pan 20 from the lower end of. In this way, the oil in the cam chamber 11 is reliably returned to the oil pan 20 only by gravity.

During this time, from the crank chamber 15 to the cam chamber 1
A breather passage 22 through which air flows toward the cam chamber 11 is provided on the upper surface side of the cylinder block 2.
The oil return passage 29 through which oil flows from the cylinder block 2 toward the crank chamber 15 is provided on the lower surface side of the cylinder block 2 and is placed far apart from each other, so that the air flow and the oil flow interfere with each other. Never. Journal through hole 23
Although the flow of air and the flow of oil will be opposite to each other at the lower end of the cylinder, the cross-sectional area of that part is sufficiently large so that these flows will not be hindered.

When the engine 1 is running at low speed, the swirling wind inside the crank chamber 15 is weak, so the blow-by gas inside the crank chamber 15 also flows into the breather passage 22 through the opening 22a provided at the upper part of the front end surface of the crank journal wall ₁₈₂ . do. Although there is little oil mist contained in the blow-by gas flowing in from the opening 22a, the oil mist is further separated in the breather chamber 24. Then, the blow-by gas is sucked into the intake manifold 27 through the PCV valve 26 and the PCV tube 28,
It is returned to the combustion chamber 5.

In this way, the operation of the PCV system and the return performance of oil from the cam chamber 11 are maintained well in each operating range of the engine 1.

By making the journal through-hole 23 substantially perpendicular to the cylinder axis LL as described above, the length of the through-hole 23 becomes the shortest, and the flow resistance of the air flowing therein can be reduced. . In addition, by forming the small-diameter narrowed portion 23a in the middle portion of the through hole 23, the rigidity of the crank journal wall ₁₈₂ can be ensured.
Furthermore, by forming the breather chamber 24 at the upper end of the through hole 23, the oil mist can be easily separated by the diffusion effect, and there is no need to provide a large volume breather chamber outside the cylinder block 2. Therefore, the engine 1 can be made compact.

In the case of an in-line four-cylinder engine, such a journal through hole 23 is preferably provided in the second crank journal wall 18 ₂ or 18 ₄ from the end as described above. That is, in an in-line four-cylinder engine, the left and right cylinders 3 ₁ , 3 ₂ and 3 ₃ ,
Since the explosion steps are carried out alternately at points 3 _{and 4} , the greatest load is applied to the central crank journal wall ₁₈₃ . In addition, the crank journal walls 18 ₁ at both ends,
₁₈₅ receives a large uneven load due to the auxiliary equipment and flyholes attached to both ends of the crankshaft 17, respectively. Therefore, the second crank journal wall 18 ₂ from the end has a relatively small load.
Alternatively, if the through hole 23 is provided at 18 ₄ , problems in terms of rigidity will be minimized, and the through hole 23 will be
3 can have a large area. Moreover,
Since there is a relatively large space above the crank journal walls 18 ₂ and 18 ₄ , it becomes easy to provide the breather chamber 24 , the PCV valve 26 , and the like.

When the oil hole 25 is provided in the central crank journal wall 18 ₃ , the oil hole 25 is made as small as possible in diameter so as not to affect the rigidity of the crank journal wall 18 ₃ .
However, the crank journal wall 18 ₃
If the oil hole 25 is sufficiently reinforced, the oil hole 25 can be made to have a relatively large diameter. In this way, air can also flow through the oil hole 25, and a sufficient air flow rate can be ensured when the engine rotates at high speed.

In the above embodiment, the oil return passage 29 is provided in the same partition wall 21 ₂ where the breather passage 22 is provided, and one end of the oil return passage 29 opens at the lower end of the journal through hole 23. However, the oil return passage 29 can also be provided in another partition, for example ₂₁₄ , and communicated with the oil pan 20 through an opening separate from the journal through-hole 23. In this way, the air passage and the oil passage can be completely separated.

Further, in the above embodiment, the crank journal wall 18 ₂ in which the journal through hole 23 is provided
and the partition wall 21 ₂ connected thereto, the breather passage 2
However, the breather passage 22 may be provided in the adjacent partition wall ₂₁₃ . By doing so, separation of oil mist in the breather chamber 24 can be performed more reliably.

(Effects of the invention) As is clear from the above explanation, according to the invention, in a flat engine, a breather passage that communicates the crank chamber and the cam chamber is provided on the upper surface side of the cylinder block, and the oil in the cam chamber is The oil return passage that returns the oil to the oil pan is provided on the bottom side of the cylinder block.
The air flow and the oil flow, which flow in opposite directions, no longer interfere with each other and can flow smoothly. Moreover, since the oil return passage is provided on the lower surface of the cylinder block, the oil in the cam chamber can be reliably returned to the oil pan by gravity.

Since the breather passage provided on the upper surface side of the cylinder block and the lower part of the crank chamber are communicated with each other by a journal through hole that vertically passes through the crank journal wall, it is possible to avoid swirling wind generated inside the crank chamber. First, sufficient air can be sent from the crank chamber to the cam chamber. Furthermore, since the air passage is provided within the cylinder block, the engine becomes compact.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of a flat engine according to the present invention, and FIG. 2 is a cutaway plan view of the cylinder block and crankcase portion thereof. DESCRIPTION OF SYMBOLS 1...Flat engine, 2...Cylinder block, _3,31-34 ...Cylinder, ₄ ...Cylinder head, 11...Cam chamber, 13...Cylinder block front end, 14...Crank case, 15...
...Crank chamber, 18 ₁ to 18 ₅ ... Crank journal wall, 20 ... Oil pan, 21 ₁ to 21 ₄ ...
Cylinder partition wall, 22... Breather passage, 23...
... Journal through hole, 24 ... Breather chamber, 29 ... Oil return passage, L-L ... Cylinder axis line.

Claims (1)

[Claims for Utility Model Registration] (1) A cylinder block installed so that the cylinder axis is substantially horizontal, a cylinder head attached to one end surface of the cylinder block, and a cylinder head attached to the other end surface of the cylinder block, A flat engine comprising: a crankcase forming a crank chamber together with an end of the cylinder block; and an oil pan provided at a lower portion of the crank chamber; the crank chamber and a cam chamber inside the cylinder head. A breather passage for communication is provided on the upper surface side of the cylinder block, and an oil return passage for returning oil in the cam chamber to the oil pan is provided on the lower surface side of the cylinder block, and the breather passage and the oil pan are connected to each other. A flat engine having a breather passage formed by communicating through a journal through-hole that passes vertically through a crank journal wall provided in a cylinder block. (2) A flat engine having a breather passage according to claim 1, wherein the upper end of the journal through-hole is a breather chamber. (3) A flat engine having a breather passage according to claim 1, wherein the journal through-hole is substantially perpendicular to the cylinder axis. (4) The cylinder block has four cylinders arranged in series, and the journal through hole is provided in a crank journal wall between the endmost cylinder and the second cylinder. A flat engine having a breather passage according to claim 1 of the registered utility model claim.