JPS6040717A - Forced ventilation device for crank case of internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent the pulsation of pressure in a crank case at the time of low-load operation from spreading into a suction pipe while increasing the detecting accuracy of an air-flow meter by providing a passage-cross section controlling mechanism midway in the passage of a blow-by gas and controlling this mechanism in accordance with the load condition of an engine. CONSTITUTION:In a low-load and low-rotation regions of an engine, an actuator 25 is controlled to reduce the opening of a blow-by gas throttle valve 22, by means of a control circuit 26 into which the output signals of a potentiometer 29 which outputs the signal for opening of a suction throttle valve 2, and a distributor 3 which outputs the signal for the rotation of engine, are inputted. As a result, the pulsation of pressure generated in a crank case 19 is damped down at the throttle valve 22, and prevented from spreading into a suction pipe 1. On the other hand, except at the time of low-load operation, the opening of the blow-by gas throttle valve 22 is increased by means of the control circuit 26, allowing the gas which failed to flow into the suction pipe 1 through a blow-by gas return passage 7, to flow into the suction pipe 1 through the blow-by gas passage 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for forced ventilation of the crankcase of an internal combustion engine. Normally, water vapor and fuel vapor are generated in the crankcase, and blow pie gas successively flows into the crankcase.The present invention relates to a device for forcibly returning these gases, particularly blow pie gas, to the intake pipe.

BACKGROUND OF THE INVENTION Conventionally, as a crankcase forced ventilation system, there is one shown in FIG. 1, for example. This figure shows an internal combustion engine equipped with a fuel injection device equipped with a conventional crankcase forced ventilation system. That is, in this figure, 1 is an intake pipe, 2 is a throttle valve, 3 is a fuel injection nozzle, and 4 is a fuel injection control circuit. The crankcase forced ventilation system includes a blow-by gas passage 6 whose one end communicates with the crankcase via the head cover 5 and whose other end communicates with the intake pipe 1 on the upstream side of the throttle valve 2; A blow pie gas return passage 7 is provided, which communicates with the crankcase and whose other end communicates with the intake pipe 1 on the downstream side of the throttle valve 2.

Furthermore, in this conventional device, the blow pie gas return passage 7
The inner diameter of the opening 8 to the intake pipe 1 is narrowed to between 1 and 2, while the opening 9 of the blow-by gas passage 6 to the intake air g1
The inner diameter is 4 to 8 pieces.

To explain the operation of the conventional device configured as described above, a part of the air introduced into the intake pipe 1 via the near cleaner 10 flows into the Zolloby gas passage 6 through the opening 9. The air that has entered the blow-by gas passage 6 flows in the direction of arrow F1, flows into the head cover 5, and further descends to the crankcase. Air containing blow pie gas in the crankcase flows into the blow pie gas return passage 7 through the head cover 5, flows in the direction of arrow F3, and flows into the intake pipe 1 through the opening 8.

The blow pie gas that has returned to the intake pipe 1 is supplied to the combustion chamber together with the intake air that has passed through the throttle valve 2 and the fuel injected from the fuel injection nozzle 3, where it is combusted.

Blow-by gas passage 6 and blow-by gas return passage 7
The air flow is caused by a pressure difference between the negative pressure in the intake pipe 1 on the downstream side of the throttle valve 2 and the atmospheric pressure or the pressure in the crankcase.

Next, the operation of this conventional device under light load operating conditions of the internal combustion engine will be explained. At this time, the opening degree of the throttle valve 2 is small, and the negative pressure in the intake pipe 1 on the downstream side of the throttle valve 2 is large. Therefore, the amount of air flowing into the intake pipe 1 from the blow pie gas return passage 7 tends to increase, but in order to suppress the amount of air flowing at this time, the inner diameter of the opening 8 is set in advance to a small value of 1 to 2nrtt. It is set.

If this inflow amount is too large, it will significantly disturb the air-fuel ratio of the internal combustion engine, impairing normal light-load operation. Further, the opening 9 of the blow-by gas passage 6 on the upstream side of the throttle valve 2 needs to have an inner diameter of 2 or more so that the internal pressure of the crankcase does not become higher than a predetermined negative pressure.

On the other hand, under high-load operating conditions, the amount of blow-by gas generated within the crankcase increases, while the pressure within the intake pipe 1 on the downstream side of the throttle valve 2 increases, causing the opening 8 to redden and The blow-by gas flowing into the tube 1 is rather reduced. Therefore, the blowby gas that cannot flow into the intake pipe 1 from the blowby gas return passage 7 accumulates in the crankcase, and flows back through the blowby gas passage 6 in the direction of arrow F2 as the pressure inside the crankcase increases, causing the blowby gas to open. It flows into the intake pipe 1 from the part 9.

At this time, if the inner diameter of the opening 9 is too small, the pressure inside the crankcase will rise abnormally, causing problems such as oil seeping out from the gaskets of various parts of the internal combustion engine. Therefore, the inner diameter of the opening 9 is set in advance from 4 to 8.
It is set to mm.

This value is considerably larger than the inner diameter of the opening 9 of 2 nm, which is required during the above-mentioned light load operation.

By the way, in this conventional device, the pressure pulsations of the blow-by gas generated within the crankcase are transmitted to the upstream side of the throttle valve 2 through the opening 9.
If the inner diameter of the throttle valve 2 is large, large pressure pulsations within the crankcase will be transmitted to the upstream side of the throttle valve 2, especially in the light load and low rotation range of the internal combustion engine. (For example, Jikai Showa 5
See No. 6-111251. ) Therefore, as shown in FIG. 1, when using an air flow meter 12 that uses a rotating dam plate 11, the dam plate 11 is The electric contact 13 (!: dam plate 110
A relative movement occurs with the potentiometer 14, which converts the degree of opening into an electrical signal, which is detrimental to the measurement of air flow. In the no-load, low-speed range of an internal combustion engine, such as when idling, the pressure pulsations within the crankcase are large, and the relative movement described above also becomes large, making it difficult to stably measure the amount of intake air in idling conditions. Become.

Purpose of the Invention The purpose of the present invention is to
Provides a crankcase forced ventilation system that reduces pressure pulsations in the crankcase from being transmitted to the intake pipe upstream of the throttle valve through the blow-by gas passage in the low rotation range, and can stably measure the amount of air flowing into the intake pipe. It's about doing.

Structure of the Invention In order to achieve the above object, the crankcase forced ventilation system of the present invention includes a flow passage cross-sectional area control mechanism provided in the middle of the blow-by gas passage, a detection device for detecting the load condition of the internal combustion engine, and a detection device for detecting the load condition of the internal combustion engine. and a control device that controls the opening degree of the flow path cross-sectional area control mechanism according to the load state detected by the detection device.

Operation The crankcase forced ventilation system configured as described above operates as follows. First, the load condition of the internal combustion engine, for example, the opening degree of the throttle valve, is detected by a detection device, for example, a device that measures the rotation angle of the rotating shaft of the throttle valve. The operation of controlling the opening of the flow passage cross-sectional area control mechanism installed in the middle of the blow-by gas passage is performed by a device that combines a control circuit that receives the measurement results of the opening and an electromagnetic actuator that receives the output signal of this control circuit. conduct.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic diagram showing an embodiment of the crankcase forced ventilation system according to the present invention. The crankcase forced ventilation system of this embodiment is installed in an internal combustion engine equipped with a fuel injection device. In this figure, 15 is an internal combustion engine body, 16 is a piston, 17 is a distributor, 3 is a fuel injection nozzle, and 5 is a head cover, and this head cover 5 communicates with a crankcase 19 via a communication passage 18. A throttle valve 2 is provided in the middle of the intake pipe 1, and the opening degree of the throttle valve 2 is detected by a potentiometer 20 that is interlocked with the throttle valve 2.

An air flow meter 1 is installed upstream of the throttle valve 2 in the intake pipe 1.
2 is provided, and this dam plate 1
1 is rotatable around a rotation shaft 21. Dam plate 1
1 is interlocked with an electric contact 13, which operates a potentiometer 14. 10 is an air cleaner at the inlet of the intake pipe.

One end of a blow-by gas passage 6 is connected to the head cover 5, and the other end of this blow-by gas passage 6 opens into the intake pipe 1 on the upstream side of the throttle valve 2. 9 is its opening. Furthermore, a blow-by gas return passage 7 is connected to the head cover 5 , and an opening 8 at the other end of the blow-by gas return passage 7 is connected to the intake pipe 1 on the downstream side of the throttle valve 2 .
Connect to.

In the middle of the blow-by gas passage 6, there is a flow passage cross-sectional area control mechanism 2.
2 is placed. Hereinafter, this flow passage cross-sectional area control mechanism will be simply referred to as the throttle valve 22. This throttle valve 22 has a partition wall 23 and a valve body 24, and the valve body 24 is connected to an electromagnetic actuator 25.
Driven by.

On the other hand, there is a control circuit 26 to uniformly control the drive of the internal combustion engine, and this control circuit 26 includes a potentiometer 20 that detects the opening degree of the distributor 17, the potentiometer 14 of the air flow meter 12, and the throttle valve 2.
It is configured to receive each output signal, and further configured to provide a fuel injection signal and a throttle valve opening signal to the fuel injection nozzle 3 and the electromagnetic actuator 25.

Next, the operation of this embodiment will be explained. First, to explain the operation of the internal combustion engine in the light load and low rotation range, part of the air taken into the intake pipe 1 through the air cleaner 10 flows into the blow-by gas passage 6 and flows in the direction of arrow F1. Then, it flows into the crankcase 19 via the head cover 5. Air containing the prober and gas in the crankcase 19 flows from the crankcase 19 into the blow-by gas return passage 7 via the head cover 5, flows in the direction of arrow F3, and flows into the intake pipe 1.

When the internal combustion engine is under light load, the opening degree of the throttle valve 2 is small.
This opening degree is detected by the potentiometer 20. on the other hand,
A rotation signal of the internal combustion engine is detected by the distributor 3 . These throttle valve opening degree signals and internal combustion engine rotation signals are sent to a control circuit 26, and this control circuit 26 supplies a signal to the electromagnetic actuator 25 to reduce the opening degree of the throttle valve 22. Therefore, the gap between the valve body 24 of the throttle valve 22 and the partition wall 23 becomes narrower, and the cross-sectional area of the flow path at this portion is reduced. As a result, the pressure pulsations that occur in one crankcase are attenuated at this throttle valve 22 and are hardly transmitted to the intake pipe 1 on the upstream side of the throttle valve 2.

On the other hand, when the internal combustion engine is not operating under a light load, the amount of blow-by gas generated in the crankcase 19 increases, but the opening degree of the throttle valve 2 increases and the throttle valve 2
The pressure inside the intake pipe 1 on the downstream side of the opening 8 increases.
The amount of blow-by gas that flows into the intake pipe 1 through the intake pipe 1 is actually reduced. Therefore, the blowby gas that cannot flow into the intake pipe 1 from the blowby gas return passage 7 accumulates in the crankcase 19, and as the pressure inside the crankcase 19 increases, it flows back through the blowby gas passage 6 in the direction of arrow F2. 9 into the intake pipe 1. The opening degree of the throttle valve 2 is large except when the internal combustion engine is operating under a light load.
Based on the opening signal of the throttle valve 2 and the rotation signal of the internal combustion engine, the control circuit 26 supplies the electromagnetic actuator 25 with a signal that increases the opening of the throttle valve 22 .

Therefore, at the throttle valve 22, a flow path cross-sectional area commensurate with the flow rate of blow-by gas in the direction of arrow F2 is obtained.

FIG. 6 is a partial schematic diagram showing another embodiment of the present invention. In this embodiment, the potentiometer 20 and electromagnetic actuator 25 for detecting the opening degree of the throttle valve 2 in the embodiment not shown in FIG. 2 are replaced with a mechanical throttle valve control mechanism.

That is, a lever 28 that interlocks with the rotating shaft 27 of the throttle valve 2 is connected to the rotating shaft 27 . This lever 28 is the pivot shaft 2
The throttle valve 7 is not fixedly connected to the throttle valve 7, but is urged toward the fully closing direction of the throttle valve 2 and connected. On the other hand, a control chamber 29 is provided in close proximity to the throttle valve 22, and this control chamber 29
The valve body 24 of the throttle valve 22 is controlled by the function of the valve body 24 of the throttle valve 22. The control chamber 29 includes a first plate 30 coupled to the valve body 24 of the throttle valve 22, a first bellows 31 hermetically coupled between the first plate 30 and the outer wall of the Zolloby gas passage 6, and one end. a second bellows 32 which is hermetically fixed to the outer wall of the blow-by gas passage 6 and has the same axis as the axis of the valve body 24;
and a second bellows 32 connected to the other end of the second bellows 32 on the close side.
plate 33. Furthermore, this control chamber 29 communicates with the intake pipe 1 on the downstream side of the throttle valve 2 via a thin tube 34, and communicates with the intake pipe 1 on the downstream side of the throttle valve 2.
It is configured so that its volume increases or decreases depending on the negative pressure inside.

The second plate 33 has a rod 35 extending therethrough and sealingly coupled to the second plate 33 . Inside the control room 29, the first plate 30
A first coil spring 36 is disposed coaxially with the second bellows 32 between the second plate 30 and the outer wall of the blow-by gas passage 6, and between the second plate 30 and the outer wall of the blow-by gas passage 6, A second coil spring 37 is arranged coaxially with the bellows 32. The tip of the lever 28, the rod 35, and the valve body 24 are aligned on the axis of the valve body 24, and the lever 28 is aligned with the axis of the valve body 24.
The rod 35 and the valve body 24 are configured to be able to be displaced in accordance with the movement of the valve body 8 .

Next, the operation of this embodiment will be explained. When the opening degree of the throttle valve 2 is small, the tip of the lever 28 moves to the right in FIG. 6 Move it to the right in Figure 6. When the rod 35 moves by a certain amount, the end surface of the rod 35 on the control chamber side comes into contact with the first plate 30,
As a result, the valve body 24 is moved to the right in FIG. 6 against the force of the first coil spring 36. Therefore, the cross-sectional area of the blow-by gas passage 6 is reduced at the throttle valve 22.

When the opening degree of the throttle valve 2 increases, the lever 28 returns to the left in FIG. 6, and the rod 35 and the first plate 3
0 returns to the left in FIG. 6 due to the elastic forces of the first and second coil springs 36,37. As a result, the throttle valve 22
Now, the cross-sectional area of the blow-by gas passage 6 increases.

When the internal combustion engine suddenly changes from a high load state to a light load state, the throttle valve 2 rapidly liquefies from a large opening to a small opening. At this time, if the cross-sectional area of the blow-by gas passage 6 is instantaneously reduced in response to the sudden change in the opening degree of the throttle valve 2, a large amount of blow-by gas under high load can be transferred through the blow-by gas passage 6 to the intake pipe. It will not be possible to return to 1. Therefore, in this embodiment, the above-mentioned control chamber 29 is provided to prevent the cross-sectional area of the blow-by gas passage 6 from instantaneously decreasing. That is, the control chamber 29 communicates with the intake pipe 1 via the thin tube 34 at a position 38 on the downstream side of the throttle valve 2, and when the negative pressure at the position 38 is small, that is, in a high load state of the internal combustion engine, the control chamber 29 communicates with the intake pipe 1 through the thin tube 34. The volume of chamber 29 is relatively large. At this time, when the throttle valve 2 is suddenly closed, the tip of the lever 28 moves to the right in FIG. 6 and comes into contact with the rod 35. However, tubule 3
Since it takes time to push the air in the control chamber 29 to the intake pipe 1 through the rod 4, there is a slight delay before the rod 35 pushes the first plate 30.

During this delay time, blow-by gas is sufficiently supplied to the intake pipe 1.
It is possible to return to.

As yet another embodiment, in the embodiment shown in FIG. 2, a pressure detector is attached to the intake pipe 1 downstream of the throttle valve 2 in place of the potentiometer 20 that detects the opening degree of the throttle valve. Throttle valve 2 based on pressure signal
2 can also be controlled. That is, as a detection device for detecting the load state of the internal combustion engine, any known detection means can be used in addition to the detection means used in each of the above-mentioned embodiments, and furthermore, it is possible to use any known detection means in addition to the detection means used in each of the above-mentioned embodiments. The throttle valve may be controlled using the most suitable known control method. In short, the object of the present invention can be achieved if the cross-sectional area of the blow pie gas passage can be changed depending on the load condition of the internal combustion engine.

Effects of the Invention The crankcase forced ventilation system of the present invention can change the flow passage cross-sectional area of the blow-by gas passage depending on the load condition of the internal combustion engine. This makes it possible to prevent relatively large pressure pulsations within the crankcase during light load operation from being transmitted to the upstream side of the throttle valve in the intake pipe.

As a result, harmful vibrations of the dam plate used to measure the airflow flowing into the intake pipe can be prevented, and the amount of inflowing air can be measured stably.

The present invention is also effective for intake pipes equipped with air flow rate detection elements other than dam plates; in this case, fluctuations in electrical output caused by pressure pulsations transmitted to the intake pipe can be prevented, resulting in stable The amount of intake air can be measured.

Furthermore, it is highly effective not only for measuring the amount of intake air, but also for other equipment installed upstream of the throttle valve, in eliminating measurement errors caused by fluctuations in electrical output caused by pressure pulsations. be.

On the other hand, in a high-load operating state, the cross-sectional area of the blow-by gas passage can be increased, and a relatively large amount of blow-by gas generated in the crankcase can be sufficiently returned to the intake pipe through the blow-by gas passage. As a result, abnormal pressure rise within the crankcase can be prevented.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a conventional crankcase forced ventilation system.
FIG. 2 is a schematic diagram showing one embodiment of the crankcase forced ventilation system according to the present invention, and FIG. 6 is a partially enlarged schematic diagram of another embodiment of the crankcase forced ventilation system according to the present invention. 1... Intake pipe 2... Throttle valve 6... Blow-by gas passage 7... Blow-by gas return passage 17... Distributor 19... Crank case 20... Potentiometer 22... Throttle valve 24 ... Valve body 25 ... Electromagnetic actuator 26 ... Control circuit 28 ... Lever 29 ... Control chamber 30 ... First plate 31 ... First bellows 32 ... Second bellows 33 ... ...Second plate 34...Thin tube 35...Rondo 36...First coil spring 37...Second coil spring agent Akira Asamura

Claims (1)

[Scope of Claims] (1) A blow-by gas passage that has one end communicating with the crankcase and the other end communicating with the intake pipe on the upstream side of the throttle valve; and one end communicating with the crankcase and the other end downstream of the throttle valve. A crankcase forced ventilation system for an internal combustion engine having a blow-by gas return passage communicating with an intake pipe, the crankcase forced ventilation system comprising: a flow passage cross-sectional area control mechanism provided in the middle of the blow-by gas passage; A crankcase forced ventilation system comprising: a detection device that detects a load condition; and a control device that controls the opening degree of the flow passage cross-sectional area control mechanism according to the load condition detected by the detection device. (2. In the crankcase forced ventilation system according to claim 1, the control device receives a signal from the detection device and operates the flow passage cross-sectional area control mechanism in accordance with this signal. A crankcase forced ventilation system comprising: a control circuit that generates a signal; and an electromagnetic actuator that receives a signal from the control circuit and operates the flow passage cross-sectional area control mechanism. (3) Claims 2. The crankcase forced ventilation system according to item 2, wherein the detection device includes a device for detecting the opening degree of a throttle valve and a device for detecting the rotation speed of an internal combustion engine. (4) In the crankcase forced ventilation system according to claim 2, the detection device includes a device for detecting the pressure in the intake pipe downstream of the throttle valve and a device for detecting the rotation speed of the internal combustion engine. (5) In the crankcase forced ventilation system according to claim 1, wherein the detection device is interlocked with the rotation axis of the throttle valve and a lever biased toward the closing direction; the control device has a control chamber for transmitting the movement of the lever to the flow path cross-sectional area control mechanism; a first plate coupled to a valve body of the area control mechanism; a first bellows sealingly coupled between the first plate and an outer wall of the blow-by gas passage; and one end sealed and fixed to the outer wall of the blow-by gas passage. and a second plate sealingly coupled to the other end of the second bellows; the control chamber communicates with the intake pipe downstream of the throttle valve via a capillary; The second plate has a rod passing through the second plate and sealingly coupled to the second plate, and a first coil spring is disposed between the first plate and an outer wall of the blow-by gas passage. , a second coil spring is disposed between the second plate and the outer wall of the blow-by gas passage, so that, in response to the movement of the lever, the spring is connected between one end of the lever and one end of the rond as well as the second coil spring. A crankcase forced ventilation device configured to transmit displacement through contact between the other end of the iron and the second plate.