JPH073001Y2 - Multi-cylinder inline engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a multi-cylinder in-line engine, and more particularly to a multi-cylinder in-line engine in which the cross-sectional shapes of a cylinder bore and a piston are elliptical.

[Prior Art] In general, in order to reduce the weight of an engine and reduce vibration noise,
A multi-cylinder in-line engine in which the cylinder bore and the piston are elliptical, and a plurality of cylinder bores are juxtaposed in the minor axis direction to make the longitudinal dimension of the engine smaller than that of a conventional engine having a true circular cylinder bore and to improve the engine rigidity. Is already known (see Japanese Utility Model Publication No. 55-25653).

[Problems to be solved by the device]

For example, as shown in FIG. 3, in an elliptical cylinder bore type engine having two intake / exhaust valves for each cylinder, the intake / exhaust port temporarily opened to the cylinder bore 2.
When 3, 4 are provided so that the lines D, E connecting the respective port centers are parallel to the crankshaft axis (or engine longitudinal axis) A, in the above engine, the minor diameter portion of the elliptical cylinder bore 2 is the engine longitudinal direction. Since there is a limit to the intake / exhaust port diameter that can be formed because they are arranged in the same direction, the port diameter becomes smaller compared to the in-line engine with a perfect circular cylinder bore, the intake / exhaust efficiency decreases, and the output performance tends to deteriorate. is there. On the other hand, when the intake / exhaust ports 3 and 4 are arranged so that the lines D and E connecting the respective port centers are inclined with respect to the minor axis 2a as shown in FIG. When arranging the ports, it is expected that the elliptical combustion chamber upper wall portion not occupied by the ports can be effectively used, the port diameter can be increased, and the intake / exhaust efficiency can be improved. However, when a plurality of cylinders are arranged side by side in the minor axis direction with such a port arrangement structure (FIG. 5), as shown in FIGS. 6 and 7, two intake valves 9 and The inclination angle α of 9 ′ (or the exhaust valves 10 and 10 ′) with respect to the engine central axis F,
α ′ (or β, β ′) is different from each other due to the inclined port arrangement, which complicates the structure of the cylinder head 11 and makes it difficult to process the valve lifter guide portions 11a and 11b, and adds the cam phase. There are many problems such as the need to produce the camshafts 16 and 17 that have been manufactured.

The present invention has been made in view of such problems, and
An object of the present invention is to provide a multi-cylinder in-line engine provided with an elliptical cylinder bore and a piston without reducing the exhaust port diameter and complicating the cylinder head structure.

[Means for Solving the Problems]

According to the present invention for the above purpose, in a multi-cylinder in-line engine in which the cross-sectional shapes of the cylinder bore and the piston are elliptical, a line connecting the intake / exhaust ports opening to each cylinder to the center of each intake port and the center of each exhaust port are provided. A multi-cylinder characterized in that each of the elliptic cylinder bores is formed in such a manner that the line connecting each of them is parallel to the axis of the camshaft, and the minor axis thereof is inclined at a predetermined angle with respect to the crankshaft axis. An in-line engine is provided.

[Action]

By forming the intake / exhaust port so that the line connecting the center of each intake port and the line connecting the center of each exhaust port are parallel to the camshaft axis, the inclination angles of the intake / exhaust valves extending from the camshaft are the same. To do. Further, by arranging each elliptical cylinder bore such that its minor axis is inclined at a predetermined angle with respect to the crankshaft axis, the ports can be arranged parallel to the crankshaft axis while the elliptical cylinder positioned above the bore It is possible to effectively utilize the upper wall portion of the combustion chamber and to make each port diameter large.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a bottom view of a cylinder head 1 of a multi-cylinder in-line engine according to the present invention, in which line A indicates the engine longitudinal axis that coincides with the axis of the crankshaft (not shown), and line B and C indicates the axes of the intake camshaft and the exhaust camshaft extending rearward from the lower surface of the cylinder head.

As is clear from this figure, a plurality of elliptical cylinder bores are arranged in series in the cylinder block 5 (Fig. 2) corresponding to the elliptical combustion chamber upper wall. Will have an elliptical piston (not shown) inserted. Hereinafter, the cylinder bore arrangement structure according to the present embodiment will be described with reference to FIG. According to the present invention, each cylinder bore 2 is arranged such that its minor axis 2a is inclined by an angle θ with respect to the crankshaft axis A described above. This angle θ
Effectively uses the elliptical combustion chamber upper wall when forming the intake / exhaust ports 3 and 4 in the cylinder head 1, so that each port diameter can be made as large as possible and the cylinder block longitudinal dimension is not increased so much. Is preferably set to (for example, θ≈30 °).

Further, according to the present invention, the intake port 3 and the exhaust port 4 which are opened to the above-mentioned elliptic cylinder bore 2 are:
A line D connecting the centers of the intake ports 3 and a line E connecting the centers of the exhaust ports 4 are parallel to the crankshaft axis A, in other words, the intake and exhaust camshaft axes B and C, respectively. Is positioned and formed.

FIG. 2 shows a longitudinal section of the engine taken along line II-II in FIG. In this figure, the crankshaft and the elliptical piston inserted into each cylinder bore 2 are omitted.

As is clear from this figure, the intake / exhaust ports 3 and 4 center (1st center) of the intake camshaft 6 and the exhaust camshaft 7 (corresponding to B and C in FIG. 1) via the valve lifter 8 Axis line 9 of intake / exhaust valve 9,10
When viewed from the engine longitudinal direction, a and 10a are inclined with respect to the center axis of the engine indicated by the line F by angles α and β.

The inclination angles α and β are the same in the cross section taken along the line III-III in FIG. 1 in order to arrange the lines D and E connecting the centers of the intake and exhaust ports in parallel to the axis A as described above. In this way, the intake valve 9
The axis 9a of the exhaust valve 10 and the axis 10a of the exhaust valve 10 have the same inclination angle. Therefore, the mounting angles of the valve lifters 8 on the cylinder head 1 are the same between the intake and exhaust valves, and correspondingly, the inclination angles of the valve lifter guides 1a and 1b formed on the cylinder head 1 are also absorbed. The exhaust valves will be the same. This means that when machining the valve lifter guide and assembling the valve lifter 8, the machining angle and the mounting angle are all the same on the intake and exhaust sides of the cylinder head, thus improving workability.

〔effect〕

As described above, according to the present invention, by arranging the elliptic cylinder bores with respect to the crankshaft axis, the unique shape of the cylinder bores is utilized, and a part of the upper wall of the elliptical combustion chamber located above it is effective. Therefore, it is possible to increase the diameter of the intake / exhaust valve to be arranged and improve the intake / exhaust efficiency, that is, the output performance. In addition, idling stability is improved as the valve diameter increases. Further, by forming the intake and exhaust ports so that the line passing through the center of each port is parallel to the camshaft axis, the valve shaft inclination angles between the intake valves or the exhaust valves are all equal, so that the cylinder head is formed. At this time, the formation angle of the valve lift guide becomes constant on the intake / exhaust side, which facilitates the manufacturing and assembling work (improving productivity). Further, since the tilt angles of the valve lifter are the same between the intake and exhaust valves due to the matching of the tilt angles, the camshaft design is not complicated by adding the phase difference of the cams. It is needless to say that the present invention makes the engine compact by adopting the elliptical cylinder bore and piston as compared with that of the conventional perfect circular cylinder bore (piston).

[Brief description of drawings]

FIG. 1 is a bottom view of a cylinder head of a multi-cylinder in-line engine according to the present invention; FIG. 2 is a longitudinal sectional view of the engine along the line II-II in FIG. 1; Is arranged so that the line passing through is parallel to the longitudinal axis of the crankshaft, and a plurality of cylinder bores are juxtaposed in the minor axis direction. Fig. 4 is a bottom view of a conventional partial cylinder head; Fig. 4 shows intake and exhaust ports. FIG. 5 is an external view showing one combustion chamber upper wall arranged so that its center line is inclined in the minor axis direction of the elliptical cylinder bore; FIG. 5 is a bottom view of a partial cylinder head having the combustion chamber upper wall shown in FIG. 4; 6 is a cylinder head sectional view taken along the line VI-VI in FIG. 5; FIG. 7 is a cylinder head sectional view taken along the line VII-VII in FIG. 2 ... Cylinder bore, 2a ... Minor axis line, 3 ... Intake port, 4
... Exhaust ports, 5,6 ... Camshaft, A ... Crankshaft axis, B, C ... Camshaft axis.

Claims (1)

[Scope of utility model registration request] 1. In a multi-cylinder in-line engine in which a cylinder bore and a piston have elliptical cross-sectional shapes, a line connecting intake / exhaust ports opening to each cylinder with a line connecting each intake port center and a line connecting each exhaust port center are respectively provided. A multi-cylinder in-line engine, characterized in that each of the elliptic cylinder bores is formed so as to be parallel to the axis of the camshaft such that its minor axis is inclined at a predetermined angle with respect to the crankshaft axis.