JPH0754629A - Blow-by gas processing device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent pressure in a crank case from excessively rising or becoming negative when a flow control valve or a check valve is frozen in cold districts. CONSTITUTION:A crank case 7 and a collecter part 10a are communicated with each other by a first blow-by gas passage 15, and the crank case 7 and a air cleaner 14 are communicated with each other by a second blow-by gas passage 20. And the air cleaner 14 and a rocker cover 3 inside are communicated with each other by a new air passage 22. The first blow-by gas passage 15 is provided with a flow control valve 19, and the second blow-by gas passage 20 and the new air passage 22 are provided with first and second check valves 21, 25. Respective check valves 21, 25 are provided with a relief mechanism to open when the difference between upper pressure and lower pressure becomes more than the fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a blow-by gas processing device configured to return blow-by gas in a crankcase of an internal combustion engine to an engine intake system.

[0002]

2. Description of the Related Art Blow-by gas processing devices have been widely used in the prior art in which fresh air is introduced into the crankcase of an internal combustion engine and the blow-by gas pushed out by the fresh air is returned to the engine intake system for combustion. There is. In a conventional blow-by gas treatment device, generally, a blow-by gas passage is provided so as to connect the throttle valve downstream position of the intake passage and the crankcase, and a fresh air passage is provided so as to communicate between the throttle valve upstream position and the crankcase. In the blow-by gas passage, a flow control valve (so-called PCV valve) whose opening degree is changed according to the negative pressure of the intake system is interposed. Therefore, due to the pressure difference between the upper and lower sides of the throttle valve, fresh air is introduced into the crankcase through the fresh air passage and blowby gas is pushed out to the intake system through the blowby gas passage. Also, the actual development 58-
Japanese Patent No. 44413 discloses a configuration in which a check valve is provided in the fresh air passage so that the blowby gas does not flow backward through the fresh air passage at the time of high load in which the amount of blowby gas increases.

[0003]

However, in the structure in which the check valve is provided in the fresh air passage as described above, when the check valve freezes while being closed by the water in the blow-by gas in the cold region, the crank valve is closed. Negative pressure in the intake pipe may act through the blow-by gas passage in the case, causing deformation of the covers such as the oil pan and the rocker cover, or damage to the seals at various parts.

When the flow control valve in the blow-by gas passage is frozen with the flow control valve closed, the pressure in the crankcase rises abnormally, causing deformation of the covers and oil leakage from various parts, or the cylinder head. From the oil to the oil pan.

Moreover, there is also a problem that the setting of the characteristics of the flow control valve becomes extremely complicated when the amount of blow-by gas during high load operation increases.

[0006]

A blow-by gas treatment apparatus for an internal combustion engine according to the present invention includes a first blow-by gas passage which connects a throttle valve downstream position of an intake passage and a crankcase, and the first blow-by gas passage. A flow control valve which is interposed and whose opening changes according to the negative pressure on the intake passage side, a second blow-by gas passage which connects the throttle valve upstream position of the intake passage and the crankcase, and the second blow-by gas. A first check valve having a relief mechanism that is interposed in the passage, allows only the flow from the crankcase to the intake passage side, and has a communication state at a predetermined differential pressure; and a throttle valve upstream position of the intake passage. A fresh air passage that communicates with the inside of the rocker cover, and a relief machine that is interposed in this fresh air passage and that allows only the flow from the intake passage to the rocker cover side and that is in a communication state at a predetermined differential pressure. It is characterized by comprising a second check valve having a.

[0007]

In the partial load range, fresh air is introduced from the intake passage into the rocker cover through the fresh air passage, and blow-by gas is discharged from the crankcase through the first blow-by gas passage into the intake passage. The flow rate of the blow-by gas is controlled by the flow rate control valve.

In the high load region, the amount of blow-by gas generated becomes large, so the entire amount cannot be processed only by the first blow-by gas passage, and the pressure in the crankcase rises. Therefore, the blow-by gas is discharged to the intake passage also through the second blow-by gas passage. In this state, the second check valve in the fresh air passage is closed, and the reverse flow of blow-by gas is blocked.

Further, when the inside of the crankcase has a negative pressure due to the freezing of the second check valve, the relief mechanism of the second check valve is activated and the fresh air passage is brought into a communicating state.

On the contrary, when the flow control valve and the first check valve freeze and the pressure in the crankcase rises, the first
The relief mechanism of the check valve operates and the blow-by gas can be discharged through the second blow-by gas.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows an internal combustion engine equipped with a blow-by gas processing apparatus according to the present invention. In this embodiment, the cylinder block 1 and the cylinder head 2 are integrally cast, and the rocker cover 3 is attached so as to cover the upper surface of the cylinder head 2. An oil pan upper 5 and an oil pan lower 6 are attached to the lower surface of the skirt portion 4 of the cylinder block 1, and a crankcase 7 is defined thereby. The space inside the rocker cover 3 and the crankcase 7 communicate with each other through an oil drop hole 8. An exhaust manifold 9 is attached to one side surface of the cylinder head 2, and an intake manifold 10 is attached to the other side surface thereof.

Collector portion 10 of the intake manifold 10
A throttle chamber 12 having a throttle valve 11 is connected to a, and an air cleaner 14 is further provided via an intake duct 13.
Are connected.

The first blow-by gas passage 15 has one end connected to the crankcase 7 and the other end connected to the collector portion 10a downstream of the throttle valve 11. Specifically, a gas outlet chamber 17 is formed in the side portion of the cylinder block 1 side by side with the cylinder bore 16, and one end of the first blow-by gas passage 15 communicates therewith. And this gas outlet chamber 1
In the lower end opening of 7, that is, the communication part with the crankcase 7,
A baffle portion 18 for separating oil is provided. Further, a known flow rate control valve (so-called PCV valve) 19 is attached to the connection portion of the first blow-by gas passage 15 with the collector portion 10a. The flow control valve 19 has a valve body that moves due to a difference in vertical pressure,
It has a characteristic that the opening degree decreases as the negative pressure on the collector portion 10a side increases.

The second blow-by gas passage 20 has one end connected to the crankcase 7 so as to join the first blow-by gas passage 15 and the other end connected to the air cleaner 14 upstream of the throttle valve 11. A first check valve 21 is provided in the second blow-by gas passage 20 in a direction that allows only the flow from the crankcase 7 side to the air cleaner 14 side.

The fresh air passage 22 has one end connected to the air cleaner 14 upstream of the throttle valve 11 and the other end connected to the rocker cover 3. In addition, inside the rocker cover 3,
A baffle plate 23 is attached, and the fresh air passage 22 communicates with the space on the upper surface of the cylinder head 2 via a passage portion 24 defined by the baffle plate 23. A second check valve 25 is provided in the fresh air passage 22 in a direction that allows only the flow from the air cleaner 14 side to the rocker cover 3 side.

The first check valve 21 and the second check valve 25 have basically the same structure. FIG. 2 shows these check valves 21 and 25, in which an inlet case 32 having an inlet 31 and an outlet case 34 having an outlet 33 are joined so as to face each other, and between them. A relief valve seat 36 having an opening 35 is sandwiched between the two. This valve seat 3
6, a plate-shaped relief valve 37 is provided on the outlet case 34 side, and the relief spring 3 is provided.
It is pressed against the valve seat 36 with 8.
A seal ring 39 made of fluororubber or Teflon, which has excellent heat resistance and oil resistance, is disposed on the contact surface between the two, and is bonded to one of the valve seat 36 and the relief valve 37. The valve seat 36, the relief valve 37 and the relief spring 38 constitute a relief mechanism that is opened at a predetermined differential pressure. A plurality of small communication holes 40 are formed in the relief valve 37, and a mushroom-shaped elastically deformable valve element 41 is attached so as to cover the communication holes 40 from the outlet case 34 side. Like the seal ring 39, the valve body 41 is made of fluororubber, Teflon, or the like.

Next, the operation of the above embodiment will be described.

The blow-by gas flows into the crankcase 7 through the gap between the wall surface of the cylinder bore 16 and the piston ring. In the partial load range including the idle, a pressure difference is generated above and below the throttle valve 11, so that fresh air is introduced into the crankcase 7 from the rocker cover 3 side through the fresh air passage 22, and blowby gas is first introduced together with this fresh air. It is discharged to the intake system through the blow-by gas passage 15. This blow-by gas flow rate is controlled to an appropriate amount by the flow rate control valve 19. Therefore, the inside of the rocker cover 3 and the oil drop hole 8 are well ventilated, and the contact between the lubricating oil and the blow-by gas is suppressed. The second blow-by gas passage 20 has the first
Since it is closed by the check valve 21, fresh air is not introduced through the passage 20.

When the engine is decelerated, the blow-by gas is discharged through the first blow-by gas passage 15 and the fresh air is introduced through the fresh air passage 22 as in the normal partial load range. The amount is extremely small. Also, the amount of fresh air introduced is smaller than that during partial load operation.

On the other hand, in the high load region of the engine, the amount of blow-by gas generated increases and the negative pressure downstream of the throttle valve 11 weakens, so the proportion of blow-by gas discharged through the first blow-by gas passage 15 decreases. . As a result, the pressure in the crankcase 7 rises and the first check valve 2
1 opens. Therefore, the blow-by gas that cannot be completely processed in the first blow-by gas passage 15 is discharged to the upstream side of the throttle valve 11 through the second blow-by gas passage 20, and is sucked into the combustion chamber from here. At this time, the second check valve 25 in the fresh air passage 22 is closed, so that the introduction of fresh air is stopped, but the inflow of blow-by gas from the crankcase 7 into the rocker cover 3 is reliably prevented. Therefore, even if the partial load operation and the high load operation are repeated, the rocker cover 3
The contact between the blow-by gas and the oil inside is prevented, and further, the mixing of water vapor in the blow-by gas into the oil is prevented, and the oil deterioration is suppressed.

In a cold region, if the flow control valve 19 is frozen with the valve closed, the blow-by gas is discharged through the second blow-by gas passage 20 due to the pressure increase in the crankcase 7 as in the case of high load. Further, when the first check valve 21 in the passage 20 is also frozen,
When the pressure in the crankcase 7 rises to a predetermined value, the relief mechanism of the first check valve 21 operates and the pressure in the crankcase 7 is released. That is, the relief valve 3
7 moves against the urging force of the relief spring 38,
The second blow-by gas passage 20 is in a communication state through the opening 35 of the valve seat 36. As a result, blow-by gas can be discharged, and the seals and the like of various parts of the engine are protected.

When the second check valve 25 in the fresh air passage 22 is frozen with the second valve closed, the crankcase 7 becomes negative, but when the negative pressure reaches the predetermined pressure, the second check valve 25 becomes the second pressure. Since the relief mechanism of the check valve 25 operates and the fresh air can be introduced through the fresh air passage 22, the seal is prevented from being damaged due to excessive negative pressure.

The first check valve 21 and the second check valve 25
The operating pressure of the relief mechanism can be appropriately set by the diameter of the relief valve 37 and the spring force of the relief spring 38, but is, for example, 0.05 to 0.0.
It is set to about 1 kg / cm ² .

[0025]

As is apparent from the above description, according to the blow-by gas treatment apparatus for an internal combustion engine according to the present invention, even if the flow control valve or each check valve is frozen in a cold region, The relief mechanism of the two-way check valve avoids an excessive rise or excessive negative pressure in the crankcase pressure, and prevents deformation of the oil pan and damage to the seal. Further, in the high load region, the blow-by gas is discharged from the crankcase through the second blow-by gas passage, so that the blow-by gas can be reliably treated, and
It is possible to prevent blow-by gas from staying in the rocker cover.

[Brief description of drawings]

FIG. 1 is a sectional view of an internal combustion engine equipped with a blow-by gas processing device according to the present invention.

FIG. 2 is a sectional view showing a configuration of first and second check valves.

[Explanation of symbols]

 15 ... 1st blow-by gas passage 19 ... Flow control valve 20 ... 2nd blow-by gas passage 21 ... 1st check valve 22 ... Fresh air passage 25 ... 2nd check valve

Claims (1)

[Claims] 1. A first blow-by gas passage communicating between a throttle valve downstream position of the intake passage and a crankcase, and an opening degree which is interposed in the first blow-by gas passage and which corresponds to a negative pressure on the intake passage side. A variable flow control valve, a second blow-by gas passage that communicates the throttle valve upstream position of the intake passage with the crankcase, and a second blow-by gas passage interposed between the crankcase and the intake passage. And a first check valve having a relief mechanism that allows communication with a predetermined differential pressure, a fresh air passage that communicates between the throttle valve upstream position of the intake passage and the rocker cover, and this fresh air passage An internal combustion engine, comprising: a second check valve that is interposed and that allows only a flow from the intake passage to the rocker cover side and that has a relief mechanism that establishes a communication state at a predetermined differential pressure. Bro -By-gas processing equipment.