JPS5925876B2 - Exhaust gas recirculation device for diesel engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation device, and more particularly to an exhaust gas recirculation device equipped with a mechanism for controlling the intake air amount and exhaust gas amount of a diesel engine.

Conventional exhaust gas recirculation devices for diesel engines control the intake air amount and the exhaust gas recirculation amount together, so the cross section of the control valve part is rectangular as shown in Figure 2, and the recirculated exhaust gas and In order to improve mixing with intake air, the recirculated exhaust gas outlets must necessarily be arranged symmetrically.

For this reason, the exhaust gas passage must be branched from the introduction part, and the passage must have an appropriate volume so as to avoid ventilation resistance.

Therefore, the exhaust gas passage became complicated and casting of the device body was difficult.

Furthermore, since it is difficult to process the recirculated gas ejection holes from the inside of the main body, there is a drawback that the processing accuracy is poor and the control accuracy of the amount of recirculated exhaust gas is poor.

1 to 3 are diagrams showing an example of a conventional exhaust gas recirculation device for a diesel engine.

In Figure 1, the accelerator lever of the engine is directly connected to the throttle lever 2 of the exhaust gas recirculation system body 1 and the fuel pump, and when the accelerator lever is depressed, it is fixed coaxially with the throttle lever 2 of the exhaust gas recirculation system. control valve 3
The mechanism is such that as the opening degree increases, the ventilation area increases and the amount of intake air increases.

Therefore, since the amount of intake air is measured in the gap between the control valve 3 and the main body 1, a high negative pressure is generated downstream of the control valve 3.

Therefore, reflux gas can be introduced at this point.

For the recirculation of exhaust gas, a part of the exhaust gas is introduced from the engine exhaust pipe into the exhaust gas population 4 of the main body 1, passes through a passage 5, and passes over the exhaust gas nozzle 6 by a vane 7 that is a part of the control valve 3. By sliding and increasing or decreasing the area of the exhaust gas jet hole 6, the amount of recirculation is controlled through the jet hole 6 and is returned to the suction pipe.

At this time, in order to improve the mixing of intake air and recirculation gas and to eliminate imbalance in the recirculation amount between cylinders of the engine, it is necessary to provide jet holes 6 for recirculation gas on both sides of the air control valve 3.

Accordingly, the blades 7 that slide on the jet holes 6 are also provided on both sides, and the control section of the exhaust gas recirculation device has a rectangular shape as shown in the cross-sectional views of FIGS. 2 and 3.

The control accuracy of the amount of exhaust gas recirculation is influenced by the processing accuracy of the rectangular portion and the control valve 3.

However, even if the control valve 3 can be machined with good precision, the rectangular portion of the main body 1 is limited by its shape, making it difficult to machine and having poor precision.

Further, a complicated shape with branched exhaust passages 5 as shown in FIG. 2 is difficult from a casting standpoint, and furthermore, since the ejection holes 6 are opened inside the main body 1, there is a drawback that precise machining is not possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas recirculation device for a diesel engine that can improve the machining accuracy of the sliding portion of the exhaust gas outlet on the inner wall of the intake pipe and the control valve.

In the present invention, a hollow cylindrical block having a separate air passage is interposed and fixed in a passage formed in the main body of the exhaust gas recirculation device, and a control valve for air control is inserted into the air passage, and a control valve for air control is provided at both ends of the control valve. The feature is that a vane for measuring exhaust gas is fixedly placed in the vane, and exhaust gas is supplied from an exhaust gas outlet opening opposite the vane.

An embodiment of the present invention will be described based on FIGS. 4 to 8.

FIG. 4 is a diagram showing the shape of a block forming the exhaust gas recirculation amount control section of this embodiment during processing.

The hollow cylindrical block 8 is provided with an exhaust gas introduction passage communicating with the exhaust gas port 4 formed in the main body 1.

This block 8 is machined with a cutter C as shown in FIG. is formed into the shape shown in FIG. 5a.

The block 8 thus formed is fitted into a cylindrical passage provided in the main body 1, as shown in FIGS. 6 to 8, to form an exhaust gas recirculation device.

When the block 8 is assembled integrally with the main body 1, the control valve 3 and the blades 7 fixed to both ends of the control valve 3 are rotatably arranged within the air passage of the block 8.

The nozzle hole 6 is opened opposite the blade 7 so that the exhaust gas is supplied, and therefore the exhaust gas is supplied to the nozzle hole 6 from the exhaust gas port 4 through the exhaust gas passage 5 formed in the main body. As a result, the amount of exhaust gas is controlled by the opening area determined by the blades 7 and the jet holes 6.

According to this embodiment with the above configuration, the following effects are achieved.

(1) Since the opening of the jet hole 6 for supplying exhaust gas is provided on the wall surface of the block 8 formed separately from the main body 1, there is no sliding contact with the blade 7 of the control valve 3 as shown in FIG. Machining of moving surfaces becomes easier and surface accuracy improves.

(2) Since the cylindrical block 8 is interposed and fixed to the cylindrical part provided in the main body 1, it is easy to attach the block 8 to the main body 1, and the close contact between the block 8 and the main body 1 is ensured. Therefore, exhaust gas can be prevented from being sucked into the engine through the gap between the block 8 and the main body 1.

As described above, according to the present invention, it is possible to obtain an exhaust gas recirculation device for a diesel engine that is highly accurate, compact, and durable.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view of a conventional exhaust gas recirculation device, Fig. 2 is a cross-sectional view showing the exhaust passage and the control section, and Fig. 3 is a longitudinal front view showing the shape of the exhaust gas nozzle and the exhaust passage. , FIG. 4 is a perspective view of a control section block of a diesel engine exhaust gas recirculation device according to an embodiment of the present invention in the process of being formed, and FIG. 5a is a perspective view of the block shown in FIG. 4 after completion of machining.
FIG. 5 is a longitudinal sectional view, FIG. 6 is a longitudinal sectional side view showing an embodiment of the exhaust gas recirculation device according to the present invention, FIG. 7 is a lateral plan view, and FIG. 8 is a longitudinal sectional front view. 1... Body, 2... Throttle lever, 3... Control valve, 4... Exhaust gas inlet, 5... Exhaust gas passage. , 6... Exhaust gas outlet, 7... Vane, 8... Control block.

Claims (1)

[Scope of Claims] 1(a) A passage formed in the exhaust gas recirculation device body; (b)
(c) a hollow cylindrical block configured separately from the exhaust gas recirculation device main body, interposed and fixed in the passage, and having an air passage therein; (c) an air control unit rotatably provided in the air passage; (d) blades for exhaust gas metering fixed to both ends of the control valve so as to rotate in synchronization with the control valve; (e) the hollow cylinder facing the blades; (f) an exhaust gas passage formed in the exhaust gas recirculation device main body for guiding exhaust gas to the exhaust gas outlet; Exhaust gas recirculation device.