JPS649455B2 - - Google Patents

Description

[Detailed Description of the Invention] Braking performed by closing a valve provided in the exhaust pipe is called an exhaust brake, and the exhaust brake device is used for large freight vehicles equipped with diesel engines,
It is widely installed in large buses and other vehicles and is operated together with other braking devices when sudden braking is required.

The present invention aims to increase the braking effect of an exhaust brake device when the engine is in a high-speed operating state, and is aimed at increasing the braking effect of an exhaust brake device when the engine is in a high-speed operating state.
In a V8 or V12 engine, the first exhaust flow path collects and flows the exhaust gas discharged from half of the 4 or 6 cylinders arranged in series, and the remaining cylinders among the 4 or 6 cylinders arranged in series. A second exhaust flow path is provided to collect and flow the exhaust gas, and an exhaust brake valve is provided at the confluence of the pair of exhaust flow paths, so that the exhaust brake is applied when the engine is operating at high speed. The exhaust flow path is characterized in that the pair of exhaust flow paths is given an effective pipe length that generates pulsations that sometimes make the pressure at the exhaust port a positive pressure.

FIG. 1 shows an exhaust brake device installed in a conventional in-line six-cylinder engine. In this figure, 1 is an exhaust brake valve, and 2 is an exhaust manifold. The exhaust brake valve 1 is provided immediately after the location where the exhaust manifold 2 collects exhaust gas from six cylinders.

On the other hand, in the exhaust brake device according to the present invention, the position of the exhaust brake valve is adjusted such that when the exhaust brake is applied during high-speed operation of the engine, a pulsation is generated that makes the pressure at the exhaust port a positive pressure. The effective pipe length of the exhaust flow path leading to the brake valve is selected, as shown in Figures 2 and 3.
The figure shows an exhaust brake device according to the present invention for an in-line six-cylinder engine. In these figures,
3 is the exhaust manifold of the cylinders No. 1 to No. 3, 4
are the exhaust manifolds of the cylinders No. 4 to No. 6, and 5 is the exhaust brake valve. Exhaust from the exhaust manifold 3 passes through the first exhaust flow path 6 and reaches the exhaust brake valve 5.
Then, the exhaust from the exhaust manifold 4 passes through the second exhaust flow path 7 and reaches the exhaust brake valve 5. The exhaust flow path 6 and the exhaust flow path 7 separate and flow the exhaust gas from the No. 1 to No. 3 cylinders and the exhaust gas from the No. 4 to No. 6 cylinders. The effective pipe lengths of these pair of exhaust flow paths are selected so as to "generate pulsations that make the pressure at the exhaust port a positive pressure when the exhaust brake is applied during high-speed operation of the engine." In other words, "exhaust manifold 3 + exhaust flow path 6" and "exhaust manifold 4 + exhaust flow path 7" are such that the natural vibration period of the air column due to these flow paths is synchronized with the opening/closing period of the exhaust valve when the engine rotates at high speed. Their effective pipe lengths are selected to produce positive pressure at the exhaust port.

The pulsation acts to prevent the exhaust gas from flowing out of the cylinder, increasing the braking action of the exhaust brake. The above-mentioned pulsation is a standing wave that is generated when the engine is operating at high speed, and disappears when the rotational speed of the engine decreases.

The ignition order of an inline 6-cylinder engine is 1-5-3-6-
2-4 or 1-4-2-6-3-5, cylinders No. 1 to No. 3 (first group cylinders) belonging to the exhaust flow path 6 and No. 4 to No. 4 belonging to the exhaust flow path 7 Cylinder No. 6 (second group cylinder) means that when the exhaust port of one of the three cylinders belonging to one group is opened, the exhaust ports of the other two cylinders are closed. In a relationship. This relationship occurs cyclically and causes the above-mentioned pulsations to be generated in the exhaust flow paths 6 and 7 one after another. The positive pressure generated at the exhaust port exerts a force on the exhaust gas in a direction that tends to prevent it from flowing out of the cylinder, so that the pumping loss due to the exhaust brake is increased. In the case of automobile diesel engines, the rotational speed of the engine is
The effective pipe lengths of the exhaust flow paths 6 and 7 are selected so that the pressure at the exhaust port becomes positive at about 1800 to 2000 RPM.

The embodiment shown in Fig. 2 is for an in-line 6-cylinder engine, but in the case of an in-line 4-cylinder engine, the ignition order (1-
3-2-4 or 1-4-2-3), the two cylinders belonging to the first group are divided into two cylinders belonging to the first group and the remaining two cylinders belonging to the second group. The other two cylinders belonging to the second group perform exhaust strokes alternately, so that the other two cylinders belonging to the second group also perform exhaust strokes alternately, and the position of the exhaust brake valve and the first and second exhaust flows leading to the exhaust brake valve are adjusted. The effective length of the pipe can be selected in the same way as in the case of an in-line six-cylinder engine. In addition, there is a V8 engine, which is thought to be a combination of two inline 4-cylinder engines, and an inline 6-cylinder engine.
In the case of a V12 engine, which is considered to be a collection of two cylinder engines, the two in-line 4-cylinder engine parts and the two in-line 6-cylinder engine parts are compared to the case of an in-line 4-cylinder engine and an in-line 6-cylinder engine. An exhaust flow path and an exhaust brake valve may be provided in a similar manner.

As explained above, the present invention takes into consideration the pressure state at the exhaust port, and applies a force in a direction that prevents the outflow of exhaust gas, even in terms of the pressure state.

In the illustrated embodiment, the exhaust manifold 3 of the first group of cylinders and the exhaust manifold 4 of the second group of cylinders are separate, and the exhaust brake is applied to the exhaust gas from the exhaust manifolds 3 and 4 in a separated state. Although the pipes 9 and 10 leading to the valve 5 are also separate, it is preferable to provide the exhaust manifolds 3 and 4 and the pipes 9 and 10 as an integrated part with partitions at appropriate locations. However, the appearance of a system adopting such a structure is not much different from the conventional one, except for the position of the exhaust brake valve and the number of pipe joints.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of a conventional exhaust brake device, FIG. 2 is a side view showing an example of an exhaust brake device according to the present invention, and FIG. 3 is a side view of the exhaust brake valve section of the exhaust brake device shown in FIG. FIG. DESCRIPTION OF SYMBOLS 1... Exhaust brake valve, 2, 3, 4... Exhaust manifold, 5... Exhaust brake valve, 6... First exhaust passage, 7... Second exhaust passage, 8... Exhaust brake valve,
9,10...Pipeline.

Claims (1)

[Claims] 1 In an in-line 4-cylinder engine, an in-line 6-cylinder engine, or a V8 or V12 engine with a composite structure thereof, the first exhaust that collects and flows the exhaust gas discharged from half of the 4 or 6 cylinders arranged in series. A second exhaust flow path is provided to collect and flow exhaust gas discharged from the remaining cylinders among the four or six cylinders arranged in series with the flow path,
An exhaust brake valve is installed at the confluence of these pair of exhaust flow paths, and the effective pipe length is determined to generate a pulsation that makes the pressure at the exhaust port positive when the exhaust brake is applied during high-speed operation of the engine. An exhaust brake device for an internal combustion engine, characterized in that the above-mentioned pair of exhaust flow paths is provided with an exhaust brake.