JPH04292516A - Blowby gas treatment equipment for internal combustion engine - Google Patents

Abstract

PURPOSE:To decrease oil consumption as much as possible by closing a pressure control valve interposed in a blowby gas passage to make a space inside an engine with an intake passage on the upstream of a throttle valve when the engine is under a light load and rotates at the number of revolutions below the set one, and opening the pressure control valve when the engine is in the other rotational domain. CONSTITUTION:In a blowby gas treatment equipment 20, the first blowby gas passage 21 to make an intake passage located downstream from a throttle valve device 17 communicating with the cam chamber 7 of an engine 1 is made to communicate with an intake passage located upstream from the throttle valve device 17. The second blowby gas passage 22 formed to be larger in the diameter than the first blowby gas passage 21, a PCV valve 23 and the second pressure control valve 24 are provided. The second pressure control valve 24 is closed in a rotational domain where the engine rotates under a light load and at the number of revolutions below space inside the engine can be kept at a negative pressure extending over the whole rotational domain of the engine.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-by gas treatment device for an internal combustion engine that recirculates blow-by gas in an engine interior space to an intake passage in order to maintain the engine interior space at a negative pressure.

0002

[Prior Art] Conventionally, in a four-stroke engine,
In order to prevent oil from being sucked into the combustion chamber from between the cylinder and piston during the intake stroke, a blow-by gas treatment device is used to maintain negative pressure in the internal space of the engine, which consists of the crank chamber and cam chamber. As a conventional blow-by gas treatment device of this type, for example, JP-A-56-1
There is one disclosed in Japanese Patent No. 62217. This device communicates the internal space of the engine with the intake passage downstream of the throttle valve through a first blow-by gas passage, and communicates the internal space of the engine with the intake passage upstream of the throttle valve through a second blow-by gas passage. It was constructed by interposing a first pressure control valve and a second pressure control valve, respectively. The first pressure control valve provided in the first blow-by gas passage is configured to be opened by intake negative pressure to control the blow-by gas recirculation amount, and the first pressure control valve provided in the second blow-by gas passage is The pressure control valve No. 2 had a structure in which the passage was closed when the engine was rotating at a low load, and opened when the engine was rotating at a high load. That is,
When the engine is under low load (when the negative pressure downstream of the throttle valve is large)
When the engine is under high load (when there is positive pressure in the intake passage downstream of the throttle valve), the blow-by gas passes through the second blow-by gas passage. This will cause the air to flow back into the intake passage.

[0003] In the conventional blow-by gas processing device configured as described above, when the engine is under low load, the blow-by gas is recirculated through the first blow-by gas passage due to the negative pressure in the intake passage downstream of the throttle valve. At that time, since the second blow-by gas passage is closed, the blow-by gas is sucked out of the internal space of the engine, and the pressure becomes negative. Further, when the engine is under high load, the first blow-by gas passage is closed and the second blow-by gas passage is opened, and the blow-by gas is recirculated through the second blow-by gas passage. At this time, the blow-by gas is sucked out of the internal space of the engine and the pressure becomes negative. Therefore, the pressure difference between the internal space of the engine and the combustion chamber is reduced over the entire load range, and oil can be sucked into the combustion chamber and prevented from flowing out.

0004

However, even if the blow-by gas treatment device constructed as described above is used, it has not been possible to reduce the amount of oil consumed. This is because although a large amount of blowby gas is generated when the engine is under low load and at high rotation speed, at that time the blowby gas is recirculated only through the first blowby gas passage. In other words, the capacity of the first blow-by gas passage and the first pressure control valve is set to be small in order to keep the engine running in a stable state when there is little blow-by gas at low load and low rotation speeds. Reflux cannot be completed, and the pressure inside the engine becomes positive pressure instead of negative pressure. As a result, the pressure difference between the internal space of the engine and the combustion chamber increases, causing oil to flow out.

[0005]

[Means for Solving the Problems] The blow-by gas treatment device for an internal combustion engine according to the present invention closes the second pressure control valve in a rotation range where the engine rotates at a low load and below a set rotation speed, and closes the second pressure control valve in a rotation range where the engine rotates at a low load and below a set rotation speed. It has a structure that opens in the area.

[0006]

[Operation] Blowby gas is recirculated through the first blowby gas passage when the engine is under low load and at low revolutions, and through the first and second blowby gas passages when the engine is under low load and at high revolutions. Furthermore, when the engine is under high load, the gas is recirculated through the second blow-by gas passage.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 3. FIG. 1 is a block diagram showing a blow-by gas treatment device for an internal combustion engine according to the present invention, and FIG. 2 is a block diagram showing a blow-by gas treatment device for an internal combustion engine according to the present invention.
FIG. 3 is an enlarged sectional view of the pressure control valve, and FIG. 3 is a graph showing the opening/closing region of the second pressure control valve. In FIG. 3, the opening/closing range of the second pressure control valve is divided into four regions depending on the engine speed and the load. In these figures, 1 is a 4-cycle engine, 2 is a cylinder block, and a cylinder head 3 is installed on the top of this cylinder block 2.
A cylinder head cover 4 is attached, and a crankcase 5 and an oil pan 6 are attached to the lower part. In addition, although the cylinder, piston, crankshaft, valve mechanism, etc. of this engine 1 are omitted in the drawing,
Its structure is equivalent to that conventionally known. 7 is a cam chamber formed between the cylinder head 3 and the cylinder head cover 4; 8 is a crank chamber formed within the crankcase 5; both of these spaces pass through the cylinder block 2 and the cylinder head 3. They are communicated via a gas passage 9 which is bored in this way. That is, the cam chamber 7 and the crank chamber 8 form a continuous space, which constitutes an internal space of the engine.

Reference numeral 11 denotes an intake manifold, an upstream end of which is connected to a surge tank 12, and a downstream end connected to the cylinder head 3. 13 is a turbocharger type supercharger, and the air suction side of its compressor chamber is connected to an air cleaner 15 via an air connector 14.
The air discharge side is connected to the surge tank 12 via an intercooler 16 and a throttle valve device 17. Note that the turbine chamber of the supercharger 13 is communicated with an exhaust port of the cylinder head 3 via an exhaust pipe (not shown). Furthermore, the bearings (not shown) for the rotating parts of the supercharger 13 are installed in a bearing chamber that is separated from the turbine chamber and the compressor chamber, and the oil that lubricates the turbine shaft, etc. is transferred from this bearing chamber. It is configured to be returned into the oil pan via passage 18.

Reference numeral 20 denotes a blow-by gas treatment device according to the present invention, and this blow-by gas treatment device 20 connects an intake passage downstream of the throttle valve device 17 (inside the surge tank 12 in this embodiment) and the cam chamber 7 of the engine 1. The first communicating
The blow-by gas passage 21 and the intake passage upstream of the throttle valve device 17 (in the air connector 14 in this embodiment)
a second blowby gas passage 2 communicating with the cam chamber 7 and having a larger diameter than the first blowby gas passage 21;
2, a PCV valve 23 as a first pressure control valve provided at the engine side end of the first blowby gas passage 21, and a second pressure control valve interposed in the second blowby gas passage 22. 24 mag. Said P
The CV valve 23 is opened by intake negative pressure, and when the inside of the surge tank 12 becomes positive pressure, the first blow-by gas passage 21 is opened.
The structure is similar to the conventional one. Further, the second pressure control valve 24 is constructed as shown in FIG. 2, and a cylinder 27 for moving a valve body 26 forward and backward is integrally provided in a valve box 25 as a valve body. Further, the valve box 25 is provided with a gas passage 29 separated from the cylinder 27 by a partition wall 28, and a valve seat 30 positioned closer to the cylinder than the valve body 26. One end of the valve seat 30 communicates with the outside through a circular opening 30a of the valve seat 30. The other end of the gas passage 29 communicates with the outside through a side opening of the valve box 25. 31 is a piston fitted into the cylinder 27, and this piston 31 penetrates the partition wall 28 and is inserted into the partition wall 2.
The valve body 2 is
6 and is biased in the opening direction by a compression coil spring 33 elastically loaded within the cylinder 27. A valve control device, which will be described later, is connected to the cylinder 27. The second pressure control valve 24 configured as described above has a second
A valve body portion is connected to the intake passage side pipe portion 22a of the blowby gas passage 22, and a side opening of the valve box 25 is connected to the engine side pipe portion 22b of the second blowby gas passage 22. Furthermore, in this embodiment, the intake passage side pipe part 22a and the engine side pipe part 22b communicate with each other through a bypass passage 22c having a smaller diameter than the circular opening 30a of the valve seat 30, in addition to the path passing through the second pressure control valve 24. has been done.

Reference numeral 34 denotes a valve control device for controlling the operation of the second pressure control valve 24. The valve control device 34 includes a switching valve 35 connected to the cylinder 27 of the second pressure control valve 24, a control unit 36 for driving the switching valve 35, and the like. The switching valve 35 is
The structure is such that an air passage 35a communicating with the spring chamber of the cylinder 27 is selectively communicated with two air passages: an atmosphere release passage 35b and a control air passage 35c communicating with the surge tank 12. The control unit 36 also includes a rotation speed sensor 37 that detects the engine rotation speed.
is connected, and when the engine speed is lower than a set value, the switching valve 35 is operated to select the control air passage 35c, and when the engine speed is higher than the set value, the air release passage 35b is selected. has been done.

Next, the operation of the blow-by gas treatment apparatus according to the present invention constructed as described above will be explained. First, when the engine 1 is under low load and at low rotation speed (in region A in FIG. 3), the switching valve 35 is controlled by the control unit 3.
6 to select the control air passage 35c. At this time, due to the high negative pressure inside the surge tank 12, the air in the control air passage 35c and the air passage 35a is sucked into the surge tank 12, and the piston 31 of the second pressure control valve 24 is compressed. The coil spring 33 is moved to be compressed, and the valve body 26 is seated on the valve seat 30. In this state, the second pressure control valve 24 is fully closed, blow-by gas generated in the engine internal space is sucked into the surge tank 12 through the first blow-by gas passage 21, and the engine internal space becomes negative pressure. Note that even if the second pressure control valve 24 is in a fully closed state, the second pressure control valve 24 is closed by the bypass passage 22c.
Since the blow-by gas passage 22 is in a communicating state,
A small amount of fresh air is always introduced into the engine internal space from the air cleaner 15 side via this bypass passage 22c. Therefore, the blow-by gas in the engine internal space can be smoothly recirculated, and the negative pressure in the engine internal space can be prevented from becoming too large in the low-load, low-speed region. When the engine 1 is in a low load state and has a high rotation speed (in region B in FIG. 3), the switching valve 35 is operated by the control unit 36 to select the atmosphere release passage 35b. In this case, the second pressure control valve 24
Negative pressure no longer acts on the piston 31, and the piston 31 is pushed back toward the valve seat 30 by the elastic force of the compression coil spring 33. In this state, the valve body 26 is separated from the valve seat 30 and the second pressure control valve 24 is fully opened. The blow-by gas generated in the internal space of the engine is transferred to the first blow-by gas passage 2.
Air is drawn into the surge tank 12 through the air connector 1 through the second blow-by gas passage 22 on which the negative pressure of the intake passage upstream of the supercharger 13 acts.
It is attracted to 4. That is, the blow-by gas generated in large quantities during low-load, high-speed rotation is recirculated through the two blow-by gas passages, and even at this time, the internal space of the engine can be maintained at a negative pressure. Further, when the engine 1 is under high load and rotating at low speed (at the time of region C in FIG. 3), the switching valve 35 selects the control air passage 35c. At this time, since the pressure inside the surge tank 12 is positive, the pressure is transmitted to the piston 31 of the second pressure control valve 24 via the control air passage 35c and the air passage 35a. Then, the piston 31 is pushed and moved toward the valve seat 30 by the pressure, and the second pressure control valve 24 becomes fully open. On the other hand, the first blow-by gas passage 21 is closed because the PCV valve 23 is closed by the pressure inside the surge tank 12 . That is, at this time, the blow-by gas generated in the engine internal space is recirculated through the second blow-by gas passage 22, thereby creating a negative pressure in the engine internal space. Furthermore, when engine 1 rotates at high speed under high load (
In region D in FIG. 3), the switching valve 35 selects the atmosphere release passage 35b. At this time, the piston 31 of the second pressure control valve 24 is pushed back toward the valve seat by the elastic force of the compression coil spring 33, and the second pressure control valve 24 is fully opened, and the blow-by gas generated in the engine internal space is The gas is refluxed through the second blow-by gas passage 22 . That is, when the engine 1 is under high load, blow-by gas flows through the second blow-by gas passage 22 regardless of the engine speed.
It will be passed.

Therefore, when the engine 1 is under low load and at low rotation speed, the blow-by gas flows through the first blow-by gas passage 21.
When the load is low and the rotation is high, the gas is refluxed through the first and second blow-by gas passages 22 and 23. Further, when the engine 1 is under high load, the gas is recirculated through the second blow-by gas passage 22. Therefore, the internal pressure of the engine can be maintained at a negative pressure throughout the entire rotation range of the engine 1, so that the pressure difference between the combustion chamber and the internal space of the engine can be kept small at all times.

Furthermore, since the pressure in the internal space of the engine is always low while the engine is rotating, a structure is adopted in which the bearing chamber of the supercharger 13 is communicated with the inside of the oil pan 6 via the oil passage 18, as shown in this embodiment. However, it is possible to prevent oil from leaking from the shaft seal of the bearing chamber to the turbine chamber and compressor chamber.

In this embodiment, the bypass passage 22c of the second blow-by gas passage 22 is provided as a conduit in a portion other than the second pressure control valve 24, but as shown in FIG. It can also be placed on the body. FIG. 4 is a sectional view showing another example of the second pressure control valve.
Components that are the same as or equivalent to those described above will be given the same reference numerals and detailed explanations will be omitted. In Figure 4, 4
1 is a bypass passage, and this bypass passage 41 is connected to the valve body 2.
It is formed by drilling a through hole in a portion corresponding to the circular opening 30a in 6. Further, the bypass passage 41 may be formed not only by a hole as described above but also by a simple notch. Even if the bypass passage 41 is provided in the valve body 26 in this way, the same effect as that of this embodiment can be obtained. Further, in the above-described embodiments, the blow-by gas treatment device of the present invention is applied to an internal combustion engine having a supercharger, but it can also be applied to a naturally aspirated internal combustion engine.

[0015]

Effects of the Invention As explained above, the blow-by gas treatment device for an internal combustion engine according to the present invention has the second pressure control valve
It has a structure that closes in the rotation range where the engine rotates at low load and below the set rotation speed, and opens in other rotation ranges.
The blow-by gas passes through the first blow-by gas passage when the engine is under low load and at low revolutions, and is recirculated through the first and second blow-by gas passages when the engine is under low load and at high revolutions. Furthermore, when the engine is under high load, the gas is recirculated through the second blow-by gas passage. Therefore, the internal pressure of the engine can be maintained at a negative pressure over the entire rotation range of the engine, so that the pressure difference between the combustion chamber and the internal space of the engine can be kept small at all times. Therefore, oil consumption can be kept as low as possible.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a blow-by gas treatment device for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a second pressure control valve used in the blow-by gas treatment device for an internal combustion engine according to the present invention.

FIG. 3 is a graph showing the opening/closing range of the second pressure control valve.

FIG. 4 is a sectional view showing another example of the second pressure control valve.

[Explanation of symbols]

1 Engine 7 Cam room 8 Crank chamber 9 Gas passage 11 Intake manifold 12 Surge tank 14 Air connector 17 Throttle valve device 20 Blow-by gas treatment equipment 21 First blow-by gas passage 22 Second blow-by gas passage 23 PCV valve 24 Second pressure control valve 34 Valve control device 36 Control unit 37 Rotation speed sensor

Claims (1)

[Claims] Claim 1: A first blow-by gas passage in which a first pressure control valve is interposed, which communicates an engine internal space consisting of a crank chamber and a cam chamber with an intake passage downstream of a throttle valve, and controls the amount of blow-by gas recirculated. and a second blowby gas passage connecting the engine internal space and an intake passage upstream of the throttle valve and having a second pressure control valve interposed therein, the blowby gas treatment device for an internal combustion engine comprising: A blow-by gas processing device for an internal combustion engine, characterized in that a pressure control valve is structured to close in a rotation range where the engine rotates at a low load and below a set rotation speed, and to open in other rotation ranges.