JPS60243322A - Method of improving performance of multi-cylinder engine - Google Patents

Abstract

PURPOSE:To easily improve the overall output of engine by making the valve timing overlapping angle of a cylinder which has a shorter exhaust pipe larger than that of a cylinder having a longer exhaust pipe. CONSTITUTION:The transversely-mounted V-engine has exhaust pipes 3, 5 respectively extending from the front side of a forwardly-inclined cylinder 2 and from the rear side of a rearwardly-inclined cylinder 4. Therefore, the length of the exhaust pipe 3 of the forwardly-inclined cylinder 2 is longer than the exhaust pipe 5 of the rearwardly-inclined cylinder 4. In the present embodiment, the valve timing overlapping angle of the rearwardly-inclined cylinder 4 having the shorter exhaust pipe 5 is made larger than that of the forwardly-inclined cylinder 2 having the longer exhaust pipe 3. The difference of angle between the cylinders 2, 3 is set in the range of 1-60 deg.. By this constitution, the overall engine output can be improved without modifying intake and exhaust pipes, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for improving the performance of a multi-cylinder engine having exhaust pipes of different lengths.

[Prior art]

FIG. 1 shows a V-type engine and its intake and exhaust system.

The type (1) engine 1 is generally mounted horizontally on the vehicle body. Then, in the forward-tilting cylinder block (forward-tilting cylinder) 2, exhaust is exhausted from the front side to the rear of the vehicle body through the exhaust pipe 3, and the rear-tilting cylinder block (backward-tilting cylinder) is
4, the exhaust is discharged from the rear side to the rear of the vehicle body through an exhaust pipe 5.

Therefore, in such a ■ type engine 1, the exhaust pipe 3
tends to be longer than the exhaust pipe 5.

In addition, in such engine 1, due to the influence of pulsation, when the exhaust pipe length becomes long, the engine output performance becomes a low-speed type (performance curve B in Fig. 2), and when it becomes short, the engine output performance becomes a high-speed type (performance curve B in Fig. 2). It is known that

Therefore, in the ■ type engine 1, the overall output characteristics of the engine will produce an output pot in a certain rotation speed range, and as a result, there is a possibility that the drivability will be reduced. Attempts have been made to match the substantial output characteristics of both cylinders 2.4 by increasing the length of the exhaust pipe 5 or increasing the diameter of the exhaust pipe 2. .

From this point of view, the inventor of the present application also set the overlap angle of the valve timings of the cylinder 2 having the long exhaust pipe 3 to be larger than the overlap angle of the valve timings of the cylinder 4 having the short exhaust pipe 5. , we have previously provided a method for matching the substantial output characteristics of both cylinders 2.4.

In the process of conducting such engine performance improvement tests, the inventor determined that, contrary to the above method, the valve timing overlap angle of the cylinder 4 having a short exhaust pipe 5 was changed to that of a cylinder having a long exhaust pipe 3. It has been found that when the overlap angle of the valve timings is set to be larger than the overlap angle of the valve timing shown in Fig. 2, the overall output is improved.

[Object of the Invention] An object of the present invention is to provide a method for improving the performance of a multi-cylinder engine that can improve the output without making any changes to the intake or exhaust pipes or the like.

[Structure of the invention]

That is, in the present invention, the overlap angle of the valve timing of the cylinder with a short exhaust pipe is set to be larger than the overlap angle of the valve timing of the cylinder with a long exhaust pipe, and the cylinder with the short exhaust pipe has the same specifications. The above objective is achieved by making it a faster type.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

In the embodiment, the present invention is applied to the engine 1 shown in FIG. This engine 1 is a V-type horizontal engine, and exhausts waste gas from the front side of the forward-tilting cylinder 2 and from the rear of the rear-tilting cylinder 4 to the rear of the vehicle body through exhaust pipes 3 and 5, respectively. . Therefore, in this engine 1, the exhaust pipe 3 of the forward-tilting cylinder 2 is longer than the exhaust pipe 5 of the rear-tilting cylinder 4.

The inventor used such an engine 1 and set the valve timing of the forward tilting cylinder 2 and the valve timing of the backward tilting cylinder 4 as shown in the table below.

FIG. 3 shows this table graphically. However, Fig. 3 (
Figure 3a) shows a forward tilting cylinder, and Figure 3(b) shows a backward tilting cylinder.

As is clear from these figures, the valve timing overlap angle of the forward tilting cylinder 2 is 58 degrees, and the valve timing overlap angle of the backward tilting cylinder 4 is 75 degrees.
The difference is 17 degrees.

In the engine 1 equipped with the forward-inclined cylinder 2 and the backward-inclined cylinder 4, each of which is set to such valve timing, the overall output performance is reliably improved.

In the above embodiment, the difference between the overlap angles in the valve timings of the cylinders 2 and 4 was set to 17 degrees, but the range is preferably 1 to 60 degrees.

Furthermore, in the above embodiments, the description has been given of the ■-type engine, but it goes without saying that the present invention is applicable not only to the ■-type engine but also to other types of engines as long as they are multi-cylinder engines with different exhaust pipe lengths.

〔Effect of the invention〕

As described above, in the method for improving engine performance according to the present invention, the output can be improved without making any changes to the intake and exhaust pipes or the like.

[Brief explanation of the drawing]

Fig. 1 is a conceptual side view of a ■type engine to which the present invention is applied, Fig. 2 is a graph showing the output characteristics of the forward-slanting cylinder and the backward-slanting cylinder when the specifications are the same, and Fig. 3 is the invention of the present invention. It is a figure showing the valve timing of a forward tilting cylinder and a backward tilting cylinder to which method is applied. 1. Engine, 2.. Forward tilting cylinder, 3.. Exhaust pipe, 4.. Backward tilting cylinder, 5.. Exhaust pipe. Applicant Suzuki Motor Co., Ltd. Figure 1 Figure 2 Private Office (O) Figure 7 Party;

Claims (2)

[Claims] (1) In a multi-cylinder engine with exhaust pipes of different lengths, set the valve timing overlap angle of cylinders with short exhaust pipes to be larger than the valve timing overlap angle of cylinders with long exhaust pipes. A method for improving the performance of multi-cylinder engines. (2) A method for improving the performance of a multi-cylinder engine according to claim 1, characterized in that the difference in overlap angle of valve timing between the cylinders having different exhaust pipe lengths is set in a range of 1 to 60 degrees. .