JPH0212285Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an intake throttle device for a diesel engine.

[Conventional technology]

In order to stabilize the idling operation of a diesel engine, it has been proposed in the past that a throttle valve is provided in the intake pipe and the opening degree of the throttle valve is controlled in response to the intake negative pressure downstream of the valve. As an example, Japanese Utility Model Application Publication No. 55-35373 can be mentioned.

First, an outline of the conventional device will be explained with reference to FIGS. 1 and 2. In FIG. 1, a butterfly valve 3, which is an intake throttle valve, is installed in the middle of an intake pipe 2 connected to an intake manifold 1 of a diesel engine, and the butterfly valve 3 is an intake throttle valve that opens and closes depending on the engine load and rotational speed. In the middle of the bypass passage 4, which is a passage that allows the front and rear of the intake air flow indicated by arrow A to communicate by bypassing the butterfly valve 3, there is a slide valve that is an on-off valve that allows the passage cross-sectional area of the bypass passage 4 to be changed. 5 is set.

The slide valve 5 has one end connected to a diaphragm 8 via a shaft member 9, and is connected to a vacuum detection pipe 6 for taking out intake negative pressure, which is installed downstream of the butterfly valve 3, that is, on the engine side, via a negative pressure extraction pipe 7. The slide valve 5 is controlled by introducing negative pressure into the vacuum chamber 12 within the diaphragm body 10 and operating the diaphragm 8 by the differential pressure between this negative pressure and the atmospheric pressure in the atmospheric chamber 14 within the diaphragm body 10. The intake negative pressure is kept constant over a certain rotation range.

As another prior art, the downstream opening of the bypass provided in the intake pipe is opened at a position close to the butterfly-type intake throttle valve and perpendicular to the rotation axis of the throttle valve, and the opening is located at the opening position. Japanese Utility Model Publication No. 50-735 proposes that the negative pressure outlet is provided in a nearby bypass.

[The problem that the idea attempts to solve]

However, in the conventional intake throttle device with the slide valve 5 as described above, the negative pressure outlet of the vacuum detection pipe 6 with respect to the intake pipe 2 is
As shown in FIG. 1 and FIG. 2, which is a front cross-sectional view in the X direction, the shaft 1 of the butterfly valve 3
In this case, since the pressure fluctuation is large depending on the opening degree of the butterfly valve 3, the diaphragm 8, which is operated by the negative pressure, receives the pressure fluctuation and causes the slide valve 5 to It also causes abnormal movement.

Further, oil in the blow-by gas flowing into the intake pipe 2 from the spout of the PCV pipe 20 for blow-by gas inflow, which is provided in the intake pipe 2 upstream of the intake throttle device, is transferred into the vacuum detection pipe 6. There is a problem that it is easy to enter the
This is because there was a problem with the mounting positions of the PCV pipe 20 and vacuum detection pipe 6 to the intake pipe 2.

Therefore, the present invention has been developed for a diesel engine having an intake throttle device with a slide valve for pressure regulation to keep the intake negative pressure constant as described above. The purpose of this invention is to provide an intake throttle device that does not cause pressure fluctuations and has a negative pressure outlet such as a vacuum detection pipe located at a position that is not easily affected by oil from the PCV pipe.

[Means to solve the problem]

The configuration of the intake throttle device for a diesel engine according to the present invention that achieves the above objectives is to provide a negative pressure-operated diaphragm valve in the bypass that bypasses the butterfly-type intake throttle valve attached to the intake pipe, and apply negative pressure to the diaphragm. The negative pressure take-off pipe to be supplied is opened at a position close to the circumferential direction from the position where the valve shaft of the intake throttle valve is attached, and moreover, to the downstream side of the throttle valve, and the blow-by gas return pipe is opened to the downstream side of the throttle valve. Upstream side and at a central angle from the opening position
The opening is offset by more than 60 degrees.

〔Example〕

The configuration in which the negative pressure extraction pipe is installed allows the operation of the slide valve to be stabilized because the negative pressure is extracted from areas where pressure fluctuations due to the butterfly valve are less, and the blow-by gas recirculation pipe is installed at the position offset by 60 degrees. This greatly suppresses the intrusion of oil mist into the diaphragm device and prevents oil and carbon from accumulating inside the diaphragm device.

Hereinafter, the details of the present invention will be explained with reference to the drawings. FIG. The intake throttle device which has almost the same configuration and function as the intake throttle device explained in the conventional example in the figure has been modified to change the mounting positions of the vacuum detection pipe 6 and the PCV pipe 20 with respect to the intake pipe 2, and to implement negative pressure. The outlet and the blow-by gas outlet are arranged so that they are not on a straight line or at a close angle to the axis of the intake pipe 2.

That is, the vacuum detection pipe 6 is installed near the shaft 18 of the butterfly valve 3 to make it less susceptible to pressure fluctuations due to changes in the opening degree of the butterfly valve 3, and the vacuum detection pipe 6 is provided with an orifice 19. This makes it even less susceptible to pressure fluctuations, allowing the slide valve 5 to smoothly control the pressure.

Furthermore, in the present invention, the PCV pipe 20 is designed to prevent engine oil mist in the blow-by gas flowing out from the PCV pipe 20 installed upstream of the butterfly valve 3 from entering the vacuum detection pipe 6 and having an adverse effect. The position is at least 60 degrees away from the extraction position of the vacuum detection pipe 6 relative to the intake pipe 2, as shown in FIG. 3, when viewed in the axial direction of the intake pipe 2.

Next, the operation of the intake throttle device of this embodiment will be explained with reference to FIG. In Fig. 5, the horizontal axis represents the central angle between the installation position of the PVC pipe 20 and the negative pressure extraction pipe 6 installation position, and the vertical axis represents the vacuum chamber 1.
FIG. 2 is a graph diagram showing the amount of oil that has entered the fuel tank.
FIG. 5 shows the vacuum pipe 6 in FIG. 3.
is fixed at a position approximately 30° from the valve stem, and the installation position of the PVC pipe 20 is set at a central angle from the pipe 6.
Installed at each position of 10°, 15°, 20, 40°, 45°, 60°,
At each angle, the amount of oil accumulated in the vacuum chamber 12 was observed when the diesel engine was operated continuously for 10 hours.

When the negative pressure outlet position is set at 30°, unlike the conventional case where it is installed at approximately 90°,
It was observed that the operation of the slide valve was stable with very little pressure fluctuation.

Further, it can be seen that when the oil mist enters the diaphragm device at an angle of 60° or more, the amount of intruding oil reaches its minimum amount, as shown in the graph of FIG.
Observation of the results of long-term use of actual vehicles revealed that the conventional installation condition of pipes 6 and 20 (center angle
0°), the oil mist containing carbon in the blow-by gas accumulated in the vacuum chamber 6 and deteriorated the operation of the diaphragm 8, whereas in the intake throttle device of this embodiment, such accumulation did not occur for a long period of time. Uniquely, the reliability of the intake throttle device could be improved.

In addition, in order to more effectively prevent the mist of engine oil from the PCV pipe 20 from entering the vacuum detection pipe 6, as shown in the intake pipe 2 in another embodiment of FIG. , the end of the vacuum detection pipe 6 may be made to protrude from the inner wall of the intake pipe 2.

[Effect of idea]

Since the intake throttle device for a diesel engine according to the present invention is configured as described above, the following effects can be obtained.

In other words, since no pressure fluctuation occurs in the negative pressure detected from the downstream side of the butterfly valve for intake throttling, the passage cross-sectional area of the bypass passage can be smoothly controlled, and the negative pressure outlet is connected to the blow-by gas outlet and the intake pipe. Since they are separated by more than 60 degrees when viewed in the axial direction, engine oil mist from the PCV pipe can be prevented from entering through the negative pressure outlet, and it will not adversely affect the diaphragm that operates the slide valve.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of the main part of the intake throttle device of a conventional diesel engine, Fig. 2 is a front sectional view of the intake pipe in Fig. 1 seen from the X direction, and Fig. 3 is an embodiment of the present invention. FIG. 4 is a front sectional view of the main part of the intake throttle device in another embodiment of the present invention, and FIG. 5 is a front sectional view of the main part of the intake throttle device in another embodiment of the present invention.
FIG. 3 is a graph showing experimental results of oil penetration characteristics when changing the mounting position of the PVC pipe. 2... Intake pipe, 3... Butterfly valve (intake throttle valve), 4... Bypass path, 5... Slide valve (on/off valve), 6... Vacuum detection pipe, 8...
Diaphragm, 18...shaft, 19...orifice, 20...PCV pipe.

Claims (1)

[Scope of utility model registration request] A negative pressure-operated diaphragm valve is installed in the bypass that bypasses the butterfly-type intake throttle valve attached to the intake pipe, and a negative pressure extraction pipe that supplies negative pressure to the diaphragm is installed at the position where the valve shaft of the intake throttle valve is attached. The intake air is opened downstream of the throttle valve at a position close to the circumferential direction from the opening position, and the blow-by gas recirculation pipe is opened upstream of the throttle valve and at a position shifted from the opening position by 60 degrees or more in terms of center angle. Intake throttle device for diesel engine.