JPH06193474A - Intake air throttle valve device for diesel-engine - Google Patents

Abstract

PURPOSE:To achieve a differential pressure across a valve, with which the area of an air passage is larger during a normal accelerator turn-off period, than during an overrun period. CONSTITUTION:An intake throttle device for a Diesel-engine, comprises a spring means (a spring 7, a leaf spring 19 and a coil spring 13) for urging an actuator (a leaf spring 10 and a lid 12) which is provided for blocking a hole 3 formed in an intake air throttle valve 2, so that the position of the throttle valve 2 or a position distant from the hole 3 is set to ensure a specific passage area between the throttle valve 2 and an intake passage 1, or between the hole 3 and the actuator, overcoming a load less than a specific value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine intake throttle valve device.

[0002]

2. Description of the Related Art In a diesel engine, since the rotation is controlled by controlling a fuel injection pump, an intake throttle valve, which is usually used in a gasoline engine, is not provided. However, in order to prevent the engine from over rotating, a throttle valve may be provided in the intake passage even in a diesel engine (for example, Japanese Utility Model Laid-Open No. 61-1633). For example, if the diesel injection pump fails and full injection is performed, the engine speed will increase and overrun will cause engine damage.To counter this, a method of cutting air and stopping the engine is used. , There is a method of squeezing air to set the overrun rotation speed to be equal to or lower than the allowable rotation speed.

Currently, the accelerator is off (idle)
In addition, the intake throttle valve must not be fully closed to stop the engine.Therefore, the above method is used to limit the flow rate so that the rotational speed is kept below the allowable rotational speed even when overrun occurs. Alternatively, a hole is provided in the intake throttle valve.

[0004]

However, the conventional device has the following problems. In other words, throttling the intake air when the accelerator is off may be advantageous in terms of exhaust gas purification, but when the accelerator is turned off from a high rotation speed, a considerable negative pressure occurs on the downstream side of the intake throttle valve (the piston is There is concern about adverse effects such as reciprocating and sucking but the throttle valve is closed), oil is sucked out from the cylinder, and black smoke increases due to delay in fuel metering.

In order to reduce the above problems, the conventional
The passage area when the accelerator is off is constant regardless of whether the accelerator is in a normal state or an overrun state, but the air passage area when the accelerator is normally off is larger than the air passage area when it is overrun. It is desirable to have it. However, at the time of overrun, the pressure difference between the intake throttle valve upstream side pressure and the intake throttle valve downstream side pressure becomes larger than that when the accelerator is normally off (noticeable in a supercharged engine). The difference can be used.

An object of the present invention is to utilize the fact that the pressure difference between the intake throttle valve upstream side pressure and the intake throttle valve downstream side pressure becomes large at the time of overrun, so that the air passage area when the accelerator is normally off is large when the air is overrun. The purpose is to realize a relationship larger than the passage area.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] An intake throttle valve device for a diesel engine according to the present invention for achieving the above object comprises the following devices. That is, an intake throttle valve arranged in the intake passage of a diesel engine, a passage area variable mechanism for varying the air passage area throttled by the intake throttle valve when the accelerator is off, and an upstream side and a downstream side of the intake throttle valve. An intake throttle valve device for a diesel engine, comprising: spring means that reduces the area of the throttled air passage as the pressure difference increases.

[0008]

In the intake throttle valve device for a diesel engine of the present invention, the passage area variable mechanism allows the air passage area throttled by the intake throttle valve when the accelerator is off to be variable. During overrun (accelerator off and overspeed), the intake throttle valve air passage area is controlled so that the spring means works by taking advantage of the large differential pressure of the intake throttle valve so that the overrun speed becomes the allowable speed. Squeeze. This allows overrun measures to be taken as usual or better. Normally, when the accelerator is off (idle), the pressure difference of the intake throttle valve is smaller than that at the time of overrun, so the air passage area of the intake throttle valve becomes larger than before. Therefore, the pressure on the downstream side of the intake throttle valve is weaker than before even when the pressure is negative, and problems such as oil suction from the cylinder and increase in black smoke due to a delay in fuel metering are alleviated as compared with the conventional case.

[0009]

The preferred embodiments of the present invention will be described below. First Embodiment In the first embodiment, the air passage at the time of normal accelerator off is realized larger than the air passage at the time of overrun by utilizing the difference in butterfly valve area. The details are shown in FIGS. 1 and 2. The intake passage 1 of the diesel engine has an intake throttle valve 2 of a butterfly valve.
Is provided. The intake throttle valve 2 is provided with a hole 3 on one side of the shaft 4. The intake throttle valve 2 rotates integrally with the shaft 4, and the shaft 4 has a shaft 4 at a portion extending outside the intake passage 1.
A stopper lever 5 that rotates together with the stopper lever 5 is attached. A stopper 6 is provided at a position where it contacts the stopper lever 5 when the stopper lever 5 rotates. The stopper 6 is movable and constitutes the passage area variable mechanism of the first embodiment. A spring 7 is provided for the stopper 6, and when the stopper 6 is pushed by the stopper lever 5, it is compressed to reduce the area of the air passage, and the stopper 6 is elastically biased in the direction opposite to the pushing direction of the stopper lever 5. To do. Spring 7
Constitutes the spring means of the first embodiment.

When the accelerator is normally off (idle), the intake throttle valve 2 rotates to the closing side, and a pressure difference occurs between the upstream side and the downstream side of the intake throttle valve 2. Since the hole 3 is formed only on one side of the shaft 4, the pressure receiving areas of the pressure difference are different from each other on both sides of the shaft, and a moment on the intake side acts on the intake throttle valve 2. This moment acts on the stopper 6 via the stopper lever 5, but by setting the moment due to the reaction force of the spring 7 larger than the moment due to the difference in the pressure receiving area due to the existence of the hole 3, the intake throttle valve 2 becomes Does not rotate (Fig. 1
State). In this state, the air flows through both the hole 3 and the outer peripheral clearance of the intake throttle valve 2, so the intake negative pressure on the downstream side of the intake throttle valve 2 becomes weaker than in the conventional case where only the hole is provided, and oil is sucked out. To prevent or reduce the occurrence of defects.

When the accelerator is off during overrun, the engine speed increases and the intake throttle valve 2
Since the differential pressure between the upstream side and the downstream side of the intake throttle valve 2 increases, the intake throttle valve 2 further rotates to the closed side, and the outer peripheral clearance of the intake throttle valve 2 becomes zero. Since the size of the hole 3 is determined so that the amount of air passing through only the hole 3 is reduced to the amount of air that makes the engine overrun rotation speed equal to or lower than the allowable rotation speed, damage due to overrun does not occur. Therefore, not only can engine damage due to overrun be prevented, but also problems due to overnegative pressure when the accelerator is normally off can be prevented.

Second Embodiment In the second embodiment, the air passage at the time of accelerator off is realized larger than the air passage at the time of overrun by utilizing the difference in butterfly valve area. The details are shown in FIGS. 3 and 4. In the second embodiment,
The shaft 4 of the intake throttle valve 2, which is a butterfly valve, is offset from the valve center, and the valve 2 has no hole 3. Since the other configurations are similar to those of the first embodiment, the same reference numerals are given to the corresponding portions. The stopper 6 is the second
It is the passage area variable mechanism of the embodiment, and the spring 7 constitutes the spring means of the second embodiment.

Normally, when the accelerator is off (idle), the intake throttle valve 2 rotates to the closing side, and a pressure difference occurs between the upstream side and the downstream side of the intake throttle valve 2. Since the shaft 4 is offset, the pressure receiving area is different on both sides of the shaft 4, and the closing moment acts on the intake throttle valve 2. Since the moment due to the reaction force from the spring 7 is set to be larger than this moment, the intake throttle valve 2 stops rotating at the position where it hits the stopper 6. In this state, air flows through the outer peripheral clearance of the intake throttle valve 2, but this clearance is larger than before, and the negative pressure on the downstream side of the intake throttle valve 2 becomes weaker than before.

At the time of overrun, the differential pressure between the upstream side and the downstream side of the intake throttle valve 2 increases, so the intake throttle valve 2 further rotates to the closing side, and the outer peripheral clearance (including 0) of the intake throttle valve 2 is increased.
The intake throttle valve 2 is balanced at a position where is smaller. Therefore, the overrun rotation speed becomes less than the allowable rotation speed.

Third Embodiment In the third embodiment, the butterfly valve is of a divided structure so that the air passage at the time of accelerator off is larger than the air passage at the time of overrun. The details are shown in FIGS. 5, 6 and 7. Show. In the third embodiment, an intake throttle valve 2 composed of a butterfly valve is rotatably arranged in an intake passage 1 of a diesel engine. The intake throttle valve 2 is divided into two valve portions 2a and 2b. One valve portion 2a is integrally connected to the shaft 4, and the other valve portion 2b is rotatable with respect to the valve portion 2a. By rotating the valve portion 2a, the air passage area when the accelerator is off can be changed. , Which constitutes the passage area variable mechanism of the third embodiment. The valve portion 2a and the valve portion 2b are urged by the spring 8 so as to form a linear shape, and when the bending force becomes larger than a predetermined value, the valve portion 2a and the valve portion 2b are affected by the force of the spring 8. Bends against. The spring 8 constitutes the spring means of the third embodiment.

Normally, when the accelerator is off (idle), the intake throttle valve 2 is rotated to the closing side, and a pressure difference is generated between the upstream side and the downstream side of the intake throttle valve 2. Since the spring 8 is not large, the valve portion 2a and the valve portion 2b are linearized by the spring 8 (state of FIG. 5), and a large outer peripheral clearance can be secured. Therefore, the negative pressure on the downstream side of the intake throttle valve 2 becomes weaker than in the conventional case.

At the time of overrun, the pressure difference between the upstream side and the downstream side of the intake throttle valve 2 becomes larger, so that the valve portion 2a and the valve portion 2b.
Bends against the spring 8 (state of FIG. 6), the valve portion 2b
The outer peripheral clearance becomes zero and, finally, the outer peripheral clearance becomes half of the idle clearance. Due to the reduced outer peripheral clearance, the overrun rotation speed is set to the allowable rotation speed or less.

Fourth Embodiment In a fourth embodiment, a butterfly valve is provided so that the air passage at the time of accelerator off is larger than the air passage at the time of overrun. The details are shown in FIGS. 8 and 9. In the fourth embodiment, an intake throttle valve 2 composed of a butterfly valve is rotatably arranged in an intake passage 1 of a diesel engine. The intake throttle valve 2 is provided with a hole 9 symmetrically with the shaft 4, and a leaf spring 10 is provided in the hole 9. The leaf spring 10 has a hole 9 above the intake throttle valve 2 when the downstream differential pressure is relatively small.
Although it is open, the hole closes when the differential pressure increases. The leaf spring 10 constitutes the passage area varying mechanism and spring means of the fourth embodiment.

When the accelerator is normally off, the intake throttle valve 2 rotates to the closing side, and a pressure difference occurs between the upstream side and the downstream side of the intake throttle valve 2. Since the pressure difference at this time is not so large as during overrun, the leaf spring 10 does not close the hole 9. Therefore, the area of the air passage is the sum of the outer peripheral clearance and the hole 9, and a large area can be obtained as compared with the conventional case. Therefore, the negative pressure on the downstream side of the intake throttle valve when the accelerator is normally off is weakened.

At the time of overrun, the differential pressure between the upstream side and the downstream side of the intake throttle valve 2 increases, so that the leaf spring 10 closes the hole 9. Therefore, the area of the air passage is only the outer peripheral clearance, and the overrun rotation speed is less than the allowable rotation speed.

Fifth Embodiment The fifth embodiment achieves the same function as that of the fourth embodiment by combining a coil spring and a lid, and the details are shown in FIG. In the fifth embodiment, an intake throttle valve 2 composed of a butterfly valve is rotatably arranged in an intake passage 1 of a diesel engine. The intake throttle valve 2 has a hole 1 symmetrical to the shaft 4.
1 is provided, the hole 11 is provided with a lid 12 that can be opened and closed, and the lid 12 is biased to the open side by a coil spring 13. The lid 12 constitutes the passage area variable mechanism of the fifth embodiment, and the coil spring 13 constitutes the spring means of the fifth embodiment.

When the accelerator is normally off, the intake throttle valve 2 rotates to the closing side, and a pressure difference occurs between the upstream side and the downstream side of the intake throttle valve 2. Since the pressure difference at this time is not as large as that at the time of overrun, the lid 12 has the hole 11. Therefore, the air passage area is the sum of the outer peripheral clearance and the hole 11, the air passage area can be made larger than in the conventional case, and the negative pressure on the downstream side of the intake throttle valve when the accelerator is normally off is weakened.

At the time of overrun, the differential pressure between the upstream and downstream sides of the intake throttle valve 2 increases, so that the deflection of the coil spring 13 increases and the lid 12 closes the hole 11. Therefore, the area of the air passage is only the outer peripheral clearance, and the overrun rotation speed is less than the allowable rotation speed.

[0024]

According to the present invention, the air passage area when the accelerator is off is made variable, and the spring means for reducing the air passage area as the pressure difference between the upstream side and the downstream side of the intake throttle valve is increased is provided.
Normally, when the accelerator is off, intake air is not throttled more than necessary, and the air passage area can be greatly reduced only during overrun.

[Brief description of drawings]

FIG. 1 is a sectional view of an intake throttle valve device for a diesel engine according to a first embodiment of the present invention.

2 is a front view of the device of FIG. 1. FIG.

FIG. 3 is a sectional view of an intake throttle valve device for a diesel engine according to a second embodiment of the present invention.

FIG. 4 is a front view of the device of FIG.

FIG. 5 is a cross-sectional view of an intake throttle valve device for a diesel engine according to a third embodiment of the present invention when a normal accelerator is off.

6 is a cross-sectional view of the device of FIG. 5 during overrun.

FIG. 7 is a front view of the device of FIG.

FIG. 8 is a sectional view of an intake throttle valve device for a diesel engine according to a fourth embodiment of the present invention.

9 is a front view of the device of FIG. 8. FIG.

FIG. 10 is a sectional view of an intake throttle valve device for a diesel engine according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 intake passage 2 intake throttle valve 3 hole 4 shaft 5 stopper lever 6 stopper 7 spring 8 spring 9 hole 10 leaf spring 11 hole 12 lid 13 coil spring

Claims (1)

[Claims] 1. An intake throttle valve disposed in an intake passage of a diesel engine, a passage area variable mechanism for varying an air passage area throttled by the intake throttle valve when the accelerator is off, and an upstream side of the intake throttle valve. An intake throttle valve device for a diesel engine, comprising: spring means that reduces the area of the throttled air passage as the downstream pressure difference increases.