JPS5822998Y2 - Exhaust system of engine with cylinder number control - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the exhaust system of a cylinder number control engine that performs partial cylinder operation by stopping the operation of some cylinders when the engine is under light load.

Generally speaking, fuel efficiency tends to improve when the engine is operated under a high load.For this reason, in multi-cylinder engines, when the engine load is light, the fuel supply to the two-part cylinder is cut and operation is stopped. An engine with cylinder number control has been devised in which the load on the remaining operating cylinders is relatively increased by this amount, thereby improving fuel efficiency in the light load range as a whole.

Conventionally, in this engine, as shown in Fig. 1, port liners D1 to D6 were installed in the exhaust port F1 to F6 of all cylinders 4F1 to +6 to prevent a drop in exhaust temperature, and the catalyst was installed downstream. This is done to maintain good purification effect.

An enlarged view of the port liner D1 as an example is shown in FIG. Each is shown in the figure.

As can be seen from these drawings, the port liner D1 has a cylindrical shape with a diameter somewhat smaller than the inner diameter of the exhaust port Fl, forming a slight gap H between it and the inner wall surface of the exhaust port F1. , and the exhaust port) reaches a connection point 1 with the exhaust manifold E from a predetermined position in the exhaust port Fl.

By the way, during partial cylinder operation, the exhaust temperature decreases due to relative improvements in fuel consumption and diversion combustion state, but at this time, from the idle cylinders -1 to #:6 where the working body is stopped, the temperature is reduced immediately after combustion. Since high temperature exhaust gas is not discharged, port liner D4~
This means that the effect of D6 on preventing a drop in exhaust temperature is almost ineffective.

During all-cylinder operation at high speeds and high loads, the exhaust gas temperature tends to rise, and in this case, the port liner D4~
D6 will have a negative effect on this, further encouraging this.

On the other hand, in order to suppress the drop in exhaust temperature during partial cylinder operation and prevent deterioration of the purifying action of the catalyst, the exhaust port F1 to F1, which is always in operation, is
~It is necessary to further reduce the amount of heat dissipated from the exhaust gas in F3 and the exhaust manifold E.

The present invention was developed in view of the above-mentioned circumstances, and in addition to removing the port liner in the exhaust port on the side of the deactivated cylinder,
The purpose is to reduce the amount of heat dissipated from the exhaust gas released into the exhaust system on the side of the active cylinder, simplifying the exhaust system on the side of the inactive cylinder, and at the same time reducing the exhaust temperature during partial cylinder operation.

This will be explained below with reference to the drawings.

FIG. 5 shows a first embodiment of the present invention, in which 1 is a cylinder head, -II-1, +2. =#=3 is an active cylinder that is always in operation, and +4. +5. +6 is a deactivated cylinder whose operation is suspended during partial cylinder operation.

F1 to F6 are exhaust ports formed in the cylinder head 1 and connected to each cylinder #:1 to -1i, and an exhaust manifold E is connected downstream of these exhaust ports F1 to F6.

For example, the inside of the exhaust manifold E is separated by a partition wall 2 into an exhaust manifold E1 on the active cylinder side and an exhaust manifold E2 on the idle cylinder side.

Exhaust port liners D1 to D3 are inserted into the exhaust ports F1 to F3 on the active cylinder side, as in the conventional case, and the exhaust port liners are removed from the exhaust ports F1 to F3 on the inactive cylinder side.

Assume that alloy cylinder operation is being performed.

Particularly under high load conditions, the exhaust temperature tends to rise excessively, but by removing the exhaust port liner on the side of the idle cylinder, the effect of reducing the amount of exhaust heat released by the exhaust port liner can be offset.

Therefore, at least the occurrence of overheating of the idle cylinders #=4 to Φ6 and burnout of the exhaust system can be suppressed by the amount other than the above-mentioned offset.

FIG. 6 shows a second embodiment of the present invention, in which the exhaust port liner on the active cylinder side is also removed in the same way as on the idle cylinder side.

Further, the inner circumferential surface of the exhaust manifold E1 on the operating cylinder side is entirely covered with an inner cylinder 3 that matches the shape of the exhaust manifold E1, except for the most downstream part.

As shown in FIG. 7, a minute gap 4 is provided between this inner cylinder 3 and the inner peripheral surface of the exhaust manifold E1.
further enhances the heat insulation effect of the exhaust gas from the inner cylinder 3.

Assume that partial cylinder operation is currently being performed.

In this state, the combustion state is relatively improved, so the temperature of the exhaust gas discharged from the operating cylinders -+1 to 41=3 is lowered.

However, in this embodiment, the amount of heat dissipated from the exhaust gas in the exhaust manifold E1 is reduced due to the heat insulation effect of the inner cylinder 3.
Compared to the case where the inner cylinder 3 is not provided, the temperature of the exhaust gas immediately after passing through the exhaust manifold E1 can be kept sufficiently high even during partial cylinder operation.

As a result, the exhaust gas purification effect by the catalyst downstream of the exhaust manifold, which is optimal when the temperature of the inflowing exhaust gas is equal to or higher than a predetermined value, can be maintained well.

FIG. 8 shows the exhaust port liner on the active cylinder side of the third embodiment of the present invention, for example, the exhaust port liner D1, and the remaining FIG. 9 shows the exhaust port liner on the idle cylinder side of the third embodiment, For example, the exhaust port liner D4 is shown.

The exhaust port liner D4 is the same as the conventional one, but the exhaust port liner D1 has a three-layer structure, and the middle layer is formed of a heat insulating material 5.

As a result, the effect of preventing a drop in exhaust temperature on the operating cylinder side can be enhanced, and the same effect as in the second embodiment can be obtained.

FIG. 10 shows an exhaust port liner on the active cylinder side of the fourth embodiment of the present invention, for example, an exhaust port liner D1.
FIG. 11 also shows an exhaust port liner on the deactivated cylinder side of the fourth embodiment, for example, an exhaust port liner D4.

The exhaust port liner D1 is the same as the conventional one, but the exhaust port liner D4 is shortened in the longitudinal direction and the effect of preventing a drop in exhaust temperature is weakened, so that the same effect as in the first embodiment can be obtained.

In fact, it is desirable to use a suitable combination of the first to fourth embodiments.

As explained above, the present invention eliminates or shortens the port liner in the exhaust port on the idle cylinder side and reduces the amount of heat dissipated from the exhaust gas on the active cylinder side, thereby simplifying the exhaust system on the idle cylinder side. On the other hand, it is possible to prevent the exhaust temperature from decreasing during partial cylinder operation and to prevent excessive rise in exhaust temperature during full cylinder operation, and it is possible to maintain a good exhaust gas purification effect by the catalyst.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view showing the exhaust system of a conventional engine, Figure 2 is an enlarged view of the exhaust port FI part shown in Figure 1, and Figure 3 is an enlarged view of the exhaust port FI section shown in Figure 1.
The figure is a sectional view taken along the line A-A in FIG. 2, FIG. 4 is a sectional view taken along the line B-B in FIG. Similarly, FIG. 7 is a schematic cross-sectional view showing the second embodiment, and FIG. 7 is a cross-sectional view taken along line CC in FIG.
The figure is a cross-sectional view showing the exhaust port part on the active cylinder side in the third embodiment of the present invention, FIG. 9 is a cross-sectional view showing the exhaust port part on the idle cylinder side in the third embodiment, and FIG. 10 is the present invention FIG. 11 is a cross-sectional view showing the exhaust port part on the side of the idle cylinder in the fourth embodiment, and FIG. 11 is a cross-sectional view showing the exhaust port part on the side of the idle cylinder in the fourth embodiment. DESCRIPTION OF SYMBOLS 1... Cylinder head, 2... Partition wall, 3... Inner cylinder, 4... Gap, 5... Insulating material, DI, D2, D
3, D4. D5, D6...Exhaust port liner, E, El
, F2...exhaust manifold, Fl, F2. F3. l
'i'4゜F5, F6...exhaust port, +1,
+2.83. +4. +5,41=6... cylinder.

Claims (1)

[Scope of utility model registration request] 1. In a multi-cylinder engine that is equipped with a dormant cylinder that stops operating when the engine is under light load, an operating cylinder that operates constantly, and an exhaust manifold that is divided according to each cylinder group, exhaust heat is generated only in the exhaust system on the operating cylinder side. Exhaust system for engine with cylinder number control equipped with heat insulation means. 2. The exhaust system for a cylinder number controlled engine according to claim 1, wherein the heat retaining means is formed only of an inner cylinder that covers the inner circumferential surface of the exhaust manifold. 2. The exhaust system for an engine with controlled number of cylinders as claimed in claim 1, wherein the 3° heat retention means is only a port liner provided at the exhaust port. 4. The exhaust system for a cylinder number controlled engine according to claim 3, wherein the heat retaining means is formed by a three-layer exhaust port liner using a heat insulating material in the intermediate layer. 5o The heat retaining means is formed of a port liner provided in the exhaust port and an inner cylinder that covers the inner circumferential surface of the exhaust manifold. system.