JPH0347420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake throttle device for a diesel engine.

[Conventional technology]

2. Description of the Related Art Diesel engines equipped with an intake throttle valve that is driven to open and close by a diaphragm device are known. This intake throttle valve is placed in the intake throttle position (half-open position) in order to reduce vibrations, noise, etc. when the engine is under light load such as when idling. In this intake throttle position (half-open position), negative pressure acts on the diaphragm device and the intake throttle valve moves to the intake throttle position (half-open position).
After closing it, it was adjusted using the adjustment screw.

[Problems to be solved by the present invention]

However, the adjustment using the adjusting screw has the problem that variations in the adjusted value occur during the adjustment work, and fluctuations in the adjusted value occur due to loosening of the adjusting screw due to vibration or the like.

An object of the present invention is to automatically control the half-open position of the intake throttle valve using the intake negative pressure generated when the intake throttle valve closes, thereby solving the problems of the prior art described above. It is said that

[Means to solve the problem]

This purpose includes a first diaphragm to which a rod connected to the intake throttle valve is fixed, and a first diaphragm defined by this first diaphragm and connected to a negative pressure source via a first switching valve. 1 negative pressure chamber;
a second diaphragm to which a stopper is fixed, which defines the closing position of the intake throttle valve by limiting the position of the rod when negative pressure is introduced into the first negative pressure chamber; A second negative pressure chamber defined by the intake throttle valve is provided at a position where the intake throttle valve is upstream from the intake throttle valve when the valve is closed from the half-open position, and downstream from the intake throttle valve when the intake throttle valve is from the half-open position to the valve open side. the intake negative pressure introduction port, and the second
A second switching valve selectively connects a negative pressure chamber to the negative pressure source and the intake negative pressure introduction port, and sets the intake throttle valve to a fully open position by introducing atmospheric air into the first negative pressure chamber. None, when negative pressure is introduced into the first negative pressure chamber and the stopper defines the closing position of the intake throttle valve, the intake throttle valve is closed by connecting the second negative pressure chamber to the negative pressure source. This is achieved by an intake throttle device for a diesel engine, characterized in that the intake throttle valve is set in a half-open position by setting the valve in a fully closed position and connecting the second negative pressure chamber to the intake negative pressure introduction port. Ru.

[Effect]

When atmospheric air is introduced into the first negative pressure chamber and negative pressure is supplied to the first negative pressure chamber with the intake throttle valve in the fully open position, the rod moves as the first diaphragm moves. Drive the air throttle valve to the valve closing side. At this time, the movement of the rod is limited by a stopper fixed to the second diaphragm, thereby defining the closed position of the intake throttle valve.

When the second negative pressure chamber is connected to a negative pressure source while the movement of the rod toward the valve closing side is restricted by the stopper, the stopper moves full stroke toward the valve closing side, causing the intake throttle valve to close. is the fully closed position.

Furthermore, when the second negative pressure chamber is connected to the intake negative pressure introduction port while the movement of the rod toward the valve closing side is restricted by the stopper, intake negative pressure is introduced into the second negative pressure chamber. The stopper moves in the valve closing direction, but when the intake negative pressure introduction port becomes upstream of the intake throttle valve and atmospheric pressure is introduced into the second negative pressure chamber, the stopper moves in the valve opening direction. By repeating this operation, the half-open position of the intake throttle valve is automatically controlled.

〔Example〕

Hereinafter, the present invention will be explained based on the accompanying drawings.

FIG. 1 is an overall schematic diagram showing an embodiment of the present invention, and FIG. 3 is an enlarged sectional view of section I in FIG. 1.

The intake throttle body 1 is composed of a main intake throttle valve 11, a sub intake throttle valve 12, and a link 13. 14
is the intake manifold.

The main intake throttle valve 11 is fixed to a link 13, and is opened and closed in conjunction with the accelerator by a wire 15 driven by an accelerator pedal (not shown).

Further, a wire 16 is attached to the link 13 to operate a pump lever (not shown) of an ignition pump.

The main intake throttle valve 11 is fully closed when the engine is idling. The intake throttle amount at idle and when the engine is stopped is controlled by the auxiliary intake throttle valve 12.

Next, the negative pressure control device that drives the sub-intake throttle valve 12 will be explained.

A spring 21 is included in the first shell 20,
Diaphragm 22 as first diaphragm
is stretched to form the first negative pressure chamber 23. 24 is an atmospheric chamber.

One end of a rod 25 is fixed to the diaphragm 22, and the other end of the rod 25 is pivotally supported by a link 17 fixed to the sub-intake throttle valve 12.

This first negative pressure chamber 23 is connected to the negative pressure of a vacuum pump or the like by way of piping, via a bimetallic vacuum switching valve 31 and a throttle 32 as a first switching valve, and an altitude compensator 33 as an altitude compensation valve. It is connected to a pressure source 34.

Specifically, a constriction 33 is provided in the conduit connecting the altitude compensator 33 and the bimetal vacuum switching valve 31, and the conduit between the constrictor 32 and the altitude compensator 33 is connected to the first negative pressure chamber. It is connected to 23. A spring 41 is included in the first shell 40 that is attached back to back with the first shell 20.
A second negative pressure chamber 43 is formed by enclosing a diaphragm 42 as a second diaphragm. Note that the first and second shell bodies 20 and 40
A hole 44 is bored in the back-to-back surfaces of the chamber 44, and the chamber 45 adjacent to the second negative pressure chamber 43 and the first negative pressure chamber 23 are kept airtight so that they communicate as a negative pressure chamber through a seal 26. There is.

Further, one end of a stopper 46 is fixed to the diaphragm 42, and the other end of the stopper 46 is inserted into the rod through a hole 44 bored in the back-to-back surfaces of the first and second shells 20 and 40. 25
The fixed end of the diaphragm 22 faces one end at a distance. Further, a screw 47 provided on the second shell 40 is used to adjust the fully closed position of the sub-intake throttle valve 12.

Furthermore, in a chamber 45 adjacent to the second negative pressure chamber 43, one end of a stopper 48 is fixed to the shells 40 facing each other back to back, and the other end is provided with a gap between the stopper 48 and the diaphragm 42.

Thus, the second negative pressure chamber 43 is connected to the port 18 (intake negative pressure introduction port) for detecting the intake negative pressure through a vacuum switching valve 50 serving as a second switching valve. has been done.

On the other hand, the vacuum switching valve 50 is
It is connected to a negative pressure source 34 via piping.

Further, an ignition switch 60 is connected to the vacuum switching valve 50.

Next, the operation of the intake throttle device of this embodiment will be explained.

Bimetal vacuum switching valve 31
When the temperature is low, the intake throttle is cut off, and the altitude compensator 3
3 is for cutting off the intake throttle at high altitudes to prevent the emission of white smoke and engine malfunction, and the throttle 32 is for ensuring that the intake throttle is cut by the altitude compensator 33.

That is, at low temperatures, the bimetal vacuum switching valve 31 closes the first negative pressure chamber 23.
When traveling at high altitudes, the altitude compensator 33 supplies atmospheric air to the first negative pressure chamber, thereby setting the auxiliary intake throttle valve 12 to the fully open position D (see FIG. 3).

When the temperature is not low and the vehicle is not traveling at high altitude, the high negative pressure (-400 mmHg or more) from the negative pressure source 34 is applied via the bimetal vacuum switching valve 31, the throttle 32, and the altitude compensator 33.
The pressure is transmitted to the first negative pressure chamber 23 of the diaphragm 22 .

The operating characteristics of the spring 21 in the first negative pressure chamber 23 are as shown by the solid line 70 in FIG.
The high negative pressure causes the rod 25 to perform a full stroke to the right in FIG. 1, that is, in the valve closing direction.

As a result, the fixed end of the diaphragm 22 of the rod 25 comes into contact with the other end of the stopper 46, and the closing position of the sub-intake throttle valve 12 is defined. The opening degree of the auxiliary intake throttle valve 12 at this contact position is half-open A in FIG.

When the sub-intake throttle valve 12 becomes half-open A in Fig. 3,
Intake negative pressure is generated, and the negative pressure is output from port 18.

On the other hand, since the engine is operating, the ignition switch 60 is ON, and therefore the vacuum switching valve 50 is also ON.

The negative pressure output from the port 18 is transferred to the second negative pressure chamber 4 via the vacuum switching valve 50.
3.

The operating characteristics of the spring 41 in the second negative pressure chamber 43 are as shown by the broken line 80 in FIG. It starts to work.

In this way, the stopper 46 moves to the right in FIG.
Close it to half-open position B in the diagram. This position is the required idle intake throttle position.

In this way, when the auxiliary intake throttle valve 12 closes to the half-open position B in FIG. 3, the intake negative pressure increases,
The stopper 46 is further moved to the right in FIG.
The auxiliary intake throttle valve 12 is further closed than the half-open position B.

When the auxiliary intake throttle valve 12 closes to the downstream side of the port 18 and the port 18 becomes upstream of the auxiliary intake throttle valve 12, the port 18 becomes atmospheric pressure, and the force of the spring 41 causes the stopper 46 to move to the left in FIG. , that is, it moves in the valve opening direction. Therefore, the auxiliary intake throttle valve 12 opens to the half-open position B (see FIG. 3), and negative pressure is generated in the port 18 again.

By repeating the above-described operations, the sub-intake throttle valve 12 is automatically controlled to always be at the required idle intake throttle position (half-open B), as shown in FIG. Therefore, during idling operation when the main intake throttle valve 11 that is linked to the accelerator pedal is in the fully closed state, the idle intake throttle amount is the amount due to the half-open B of the sub intake throttle valve 12.

If the engine is stopped from the idle intake throttle state, the ignition switch 60 will turn OFF.
Then, the vacuum switching valve 50 is also
OFF, and the negative pressure source 34 is in the second negative pressure chamber 43.
A high negative pressure is applied.

Therefore, the stopper 46 moves to the right in the full stroke in FIG. 1, and the auxiliary intake throttle valve 12 is fully closed, reducing vibration when the engine is stopped.

In the above embodiment, the main and sub intake throttle valves 11
Although the control in the two-valve type intake throttle provided with the intake throttle valve and 12 has been described, it goes without saying that even with the one-valve type intake throttle, it is possible to automatically control the idle intake throttle amount using the port negative pressure.

〔effect〕

According to the present invention, the intake negative pressure introduction port is provided at a position where the intake throttle valve is upstream from the intake throttle valve when the intake throttle valve is closed from the half-open position, and downstream from the intake throttle valve when the intake throttle valve is from the half-open position to the valve open side. Since the negative pressure signal drives the stopper that defines the closing position of the intake throttle valve, the intake throttle valve always
It has the advantage of being automatically controlled to the half-open position, which is the required idle intake throttle amount.

[Brief explanation of drawings]

Fig. 1 is an overall schematic configuration diagram showing an embodiment of the present invention, Fig. 2 is an operating characteristic diagram showing the operating characteristics of the springs in each negative pressure chamber, Fig. 3 is an enlarged sectional view of part I in Fig. 1,
FIG. 4 is an explanatory diagram showing port negative pressure characteristics at each intake throttle valve opening degree in FIG. 3. 10...Intake passage, 12...Sub-intake throttle valve, 18...
Negative pressure port, 22...Diaphragm, 23...First negative pressure chamber, 31...Bimetal vacuum switching valve, 33...Altitude compensator, 34...Negative pressure source, 4
2...Diaphragm, 43...Second negative pressure chamber, 50...Vacuum switching valve.

Claims (1)

[Scope of Claims] 1. A first diaphragm to which a rod connected to an intake throttle valve is fixed; and a first diaphragm defined by the first diaphragm and connected to a negative pressure source via a first switching valve. and a second negative pressure chamber to which a stopper is fixed, which defines the closing position of the intake throttle valve by limiting the position of the rod when negative pressure is introduced into the first negative pressure chamber. a diaphragm, a second negative pressure chamber defined by the second diaphragm, and a second negative pressure chamber defined by the second diaphragm; an intake negative pressure introduction port provided at a position downstream of the valve; and a second switching valve selectively connecting the second negative pressure chamber to the negative pressure source and the intake negative pressure introduction port, The intake throttle valve was brought to a fully open position by introducing atmospheric air into the first negative pressure chamber, and negative pressure was introduced into the first negative pressure chamber to define the closed position of the intake throttle valve by the stopper. Sometimes, the intake throttle valve is set to a fully closed position by connecting the second negative pressure chamber to the negative pressure source, and the intake throttle valve is set to the fully closed position by connecting the second negative pressure chamber to the intake negative pressure introduction port. An intake throttle device for a diesel engine characterized by a half-open position.