JPS6140887Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a blowby gas recirculation device for an engine that recirculates blowby gas leaked into the crankcase from the combustion chamber of the engine to the intake system in order to supply it to the combustion chamber again.

Blowby gas that leaks from the combustion chamber of the engine into the crankcase through the gap between the piston ring and the cylinder wall contains a large amount of unburned HC. Therefore, at present, blow-by gas containing a large amount of harmful HC is not released into the atmosphere, but is instead returned to the intake system for combustion treatment.

In many cases, the above-mentioned blowby gas is returned to the intake system by guiding the blowby gas from the crankcase into the cylinder head cover through a blowby gas passage bored in the cylinder block and cylinder head, and from the cylinder head cover through piping. The exhaust gas is then returned to the intake system, or it is returned to the intake system via direct piping from the crankcase.

In any case, the connection part of the blow-by gas recirculation passage to the intake system is formed by piping,
For example, when an automobile is used in an extremely cold region, the inside of this piping, especially the vicinity of the outlet of the recirculation passageway where it joins low-temperature intake air, may freeze and the recirculation passageway may become blocked. In other words, the part of the blowby gas recirculation passage that connects to the intake system generally takes into account the distribution of blowby gas to each cylinder, and is connected to the intake passage upstream of the intake manifold, so it is farthest from the cylinder block, so the heat in the combustion chamber is In addition to being difficult to convey,
Since this portion is formed of piping exposed to the atmosphere, the blow-by gas inside the piping is easily cooled by the low-temperature atmosphere, and the moisture in the blow-by gas freezes inside the piping.

For example, connect the above piping to an electric heater or
As shown in Publication No. 51-114546, piping freezing can be prevented by actively heating the exhaust gas with recirculated exhaust gas, etc., but very few engines are used in the extremely cold conditions mentioned above. It would be extremely uneconomical to apply such a complicated and troublesome treatment to all mass-produced engines. Also, place the blow-by gas recirculation passage piping at a location close to the cylinder block, such as downstream of the branch part of the intake manifold.
Alternatively, as shown in Utility Model Application No. 56-124488, if the piping is connected to the intake system at the cylinder head etc., the heat of the combustion chamber can be easily transmitted to the piping and freezing of the piping can be prevented. As a result, blow-by gas is supplied only to specific cylinders, and if distribution is taken into account, it becomes necessary to provide a recirculation passage for each cylinder, which is undesirable, especially in engines with a large number of cylinders, as the piping becomes complicated.

The present invention was made in view of the above circumstances, and aims to provide a simple blow-by gas recirculation device that can supply blow-by gas to each cylinder as evenly as possible and that does not cause piping to freeze. .

The blow-by gas recirculation device for an engine of the present invention is provided in an engine in which blow-by gas is recirculated to the intake system through the recirculation passage, as described above, in which the recirculation passage opens into the intake passage on the upstream side of the intake manifold branch. The engine is characterized by comprising a first recirculation passage which is opened to the intake manifold or an intake passage formed in the engine body downstream of the opening on the intake passage side of the first recirculation passage. be.

The piping that opens into the intake manifold near the cylinder block is easily heated by the heat from the combustion chamber, so even if the other piping freezes in extremely cold weather, it will not freeze, and the blow-by gas will be recirculated through this piping. can be done. During normal times other than freezing, blow-by gas is also supplied to the intake system through the other pipe opened to the intake passage upstream of the intake manifold branch, so blow-by gas is supplied only to specific cylinders. without any
It is distributed relatively evenly to each cylinder. Unless the other pipe is frozen, if the blow-by gas supply from one pipe is stopped or reduced, normally the blow-by gas will be supplied to each cylinder almost completely or more evenly. Ru. In order to meet these requirements, one of the pipes should be equipped with a pressure valve that opens when the other pipe freezes and the pressure inside the pipe increases, or one pipe should be connected to the other pipe. It is best to narrow it down so that it has a small diameter.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a blow-by gas recirculation device for an engine according to an embodiment of the present invention. The engine to which the blow-by gas recirculation device of this embodiment is installed is a diesel engine, and the cylinder head 2 is fixed on the cylinder block 1.
A fuel injection nozzle 3 that opens into each cylinder (not shown) is attached to the fuel injection nozzle 3 . An intake manifold 4 having an opening 4a communicating with the intake port of each cylinder is attached to the cylinder head 2. Further, a cylinder head cover 5 is attached on top of the cylinder head 2.

Although not shown in the figure, the cylinder block 1 and cylinder head 2 have a cylinder extending vertically, with a lower end in the crankcase (not shown) and an upper end in the cylinder head 2, as in many engines. A blow-by gas passage that opens on the top surface is bored. Blowby gas leaking from the combustion chamber into the crankcase through the gap between the piston ring and the cylinder wall rises into the cylinder head cover 5 through the blowby gas passage due to the internal pressure of the crankcase. As in many engines, the blow-by gas passage is an oil return passage for returning lubricating oil that has lubricated the valve train, etc. located at the top of the cylinder head 2 into the crankcase (above the oil pan). In addition, the lubricating oil as described above may be scattered inside the cylinder head cover 5, and the blow-by gas rising inside the cylinder head cover 5 contains a mist of lubricating oil. Therefore, an oil separator 6 is connected to an opening (not shown) provided in the upper part of the cylinder head cover 5, and the blow-by gas from which the lubricating oil has been separated is transferred to the intake system as will be described in detail later. is refluxed to.

An upstream end 7a of a blow-by gas hose 7 is connected to a gas discharge port 6a of the oil separator 6. The downstream end of this blow-by gas hose 7 is branched into two hoses, a first hose 7b and a second hose 7c, and the first hose 7b is connected to a blow-by gas inlet 4b opened near the cylinder head 2 of the intake manifold 4. The second hose 7c is connected to a blow-by gas inlet 8a opened in the intake passage 8 on the upstream side of the branch portion 4c of the intake manifold 4. A pressure valve 9 is attached to the blow-by gas inlet 4b opened to the intake manifold 4, which is closed when the pressure inside the hose 7 is below a predetermined value and opens when the pressure exceeds a predetermined value. .

Hereinafter, the operation of the blow-by gas recirculation device of this embodiment having the above configuration will be explained. The blowby gas that is recirculated into the intake manifold 4 from the blowby gas inlet 4b provided downstream of the branch portion 4c of the intake manifold 4 is difficult to be evenly supplied to each cylinder. In other words, a large amount of fuel is likely to be supplied to cylinders close to the suction port 4b, and it is difficult to be supplied to cylinders that are far away. However, since this suction port 4b is provided with the pressure valve 9 as described above, under normal conditions when the blow-by gas hose 7 is not frozen,
The entire blow-by gas is returned to the intake passage 8 through the second hose 7c. The blow-by gas recirculated to this intake passage 8 upstream of the branch portion 4c of the intake manifold 4 is distributed by the intake manifold 4 and evenly supplied to each cylinder.

Even if the engine is used in extremely cold weather and the inside of the second hose 7c freezes, the inside of the first hose 7b, which is located near the cylinder block 1 and through which heat from the combustion chamber is easily transferred, does not freeze. When the inside of the second hose 7c freezes and the pressure inside the hose 7 rises, the pressure valve 9 opens, and the blow-by gas is returned to the intake manifold 4 through the pressure valve 9 and the intake port 4b. As mentioned above, the return of the blow-by gas from the intake port 4 is not very desirable in terms of uniform supply to each cylinder, but the return of the blow-by gas continues in any case in response to the temporary freezing of the second hose 7c, and accidents such as oil leaks due to an increase in the internal pressure of the crankcase do not occur.

When the ambient temperature of the engine rises and the freeze inside the second hose 7c thaws, the pressure valve 9 closes and the blow-by gas is returned to the intake passage 8 and is evenly supplied to each cylinder.

In the embodiment described above, a pressure valve 9 is provided at the suction port 4b, and the entire amount of blow-by gas is switched and recirculated into the intake manifold 4 or the intake passage 8 depending on whether the hose 7 is frozen or during normal operation. However, such a means to completely switch the total amount of blow-by gas is not necessarily necessary. That is, for example, if the first hose 7b is narrowed to a smaller diameter than the second hose 7c so that normally a larger amount of blow-by gas is recirculated from the intake passage 8 than from the intake manifold 4, the blow-by gas can be distributed evenly. It will soon be distributed to each cylinder. Furthermore, even if the first hose 7b and the second hose 7c are set to have the same diameter without providing a restriction as described above, a certain amount of blow-by gas is normally returned to the intake passage 8, and the intake manifold is easily heated. Compared to the case where the blow-by gas is recirculated only to cylinders 4 and 4, the blow-by gas can be more evenly supplied to each cylinder. (Also, the first hose 7b may be configured to open into the intake port of the cylinder head instead of the intake manifold.) As explained in detail above, the engine blow-by gas recirculation device of the present invention has an extremely simple structure.
It is of high practical value because it allows blow-by gas to be recirculated so that there is no large difference in the supply amount between cylinders under normal conditions, and also to reliably recirculate blow-by gas even in extremely cold weather.

[Brief explanation of the drawing]

Figure 1 is a plan view showing one embodiment of the present invention, Figure 2 is a plan view showing one embodiment of the present invention;
The figure is an elevation view. 1...Cylinder block, 4...Intake manifold, 4b, 8a...Blow-by gas inlet, 4
c... Branch of intake manifold, 7... Blow-by gas hose, 7b... First hose, 7c...
Second hose, 8...Intake passage.

Claims (1)

[Scope of utility model registration request] In an engine in which blow-by gas is recirculated to the intake system via a recirculation passage, the recirculation passage is open to the intake passage upstream of an intake manifold branch part, and the first recirculation passage is on an intake passage side of the first recirculation passage. A blow-by gas recirculation passage for an engine, comprising a second recirculation passage that opens into an intake manifold or an intake passage formed in an engine body downstream of the opening.