JPH08144844A - Cylinder of multi-cylinder engine - Google Patents

Abstract

PURPOSE: To make the machining of a mating face possible in a state where a machining tool is separated from a skirt section, and moreover to complete its machining in a short time using a machining tool having relatively large diameter by providing a recessed face around the outer periphery of the skirt section in the case of lowering a mating face with a crankcase. CONSTITUTION: In a multi-cylinder engine having a cylinder tightly attached to a crankcase, a bolt inserting through hole 4 through which a fastening bolt passes is provided between adjacent cylinders, and a skirt section 6b which is unitedly formed from a mating face with the crank case toward a crankshaft at the time of casting of the cylinder 6 is drilledly provided in each of cylinders #1 to #4 of the cylinder 6. A recessed face 6c formed recessedly from the mating face 6a is provided between the mating face 6a and the outer periphery of the skirt section 6b, and the boss seat face 4a of the bolt inserting through hole 4 is formed on the mating face 6a. In this case, the edge part 10 of the boss seat face 4a on the side of the recessed face 6c is provided with a deviation toward the bolt inserting through hole 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cylinder of a multi-cylinder engine.

[0002]

2. Description of the Related Art A cylinder of a conventional multi-cylinder engine is shown in FIGS. FIG. 6 is a cross-sectional view of a cylinder of a conventional multi-cylinder engine taken along a plane passing through the center axis of each cylinder, and FIG. 7 is a bottom view of the cylinder of the multi-cylinder engine of FIG. FIG. 8 is a sectional view of a cylinder of another conventional multi-cylinder engine.

A conventional cylinder a shown in FIGS. 6 and 7.
Is a cylinder barrel b that constitutes the cylinder body,
It mainly comprises a sleeve c which is formed separately from the cylinder barrel b and serves as an inner surface portion of each cylinder. In this cylinder a, after casting the cylinder barrel b,
A processing tool having an outer diameter dimension indicated by symbol d in FIG. 7 is linearly moved in the parallel direction of the cylinder to machine the mating surface b1 with the crankcase, and then the sleeve c is attached to the cylinder barrel b.
The lower end of the sleeve c in the state where the sleeve c is assembled protrudes toward the crankcase side with respect to the mating surface b1 by the skirt portion c1 which is the protruding portion. The length of the sliding surface of the piston is secured.

In contrast to the cylinder a having such a skirt portion c1, the cylinder e shown in FIG. 8 is a cast-integrated type cylinder having no skirt portion. In the case of such an integral type, if the skirt portion is provided integrally, it is necessary to move the processing tool so as not to contact the skirt when processing the mating surface e1 of the cylinder e with the crankcase. However, there is an inconvenience that the number of processing steps increases. Therefore, the skirt is not formed on the cylinder e.

[0005]

By the way, in the press-fit type cylinder a, due to the structure thereof, the radial dimension of the skirt portion c1 is the radial direction of the sleeve c on the piston top dead center side (cylinder head side). The thickness of the sleeve c has a lower limit value to prevent deformation of the inner surface part that is the sliding surface of the piston and to secure the strength of the lower end of the skirt part c1. Therefore, there is a limit to narrowing the pitch between the cylinders due to the presence of the sleeve c, which causes a problem that the width dimension of the engine increases and the weight of the engine increases.

On the other hand, the cylinder e having no skirt
In this case, since the dimension of the inner surface of the cylinder d, which is the sliding surface of the piston, in the sliding direction is short, the lower part of the piston at the bottom dead center of the piston is made to project from the lower end of the cylinder e, or the crankcase It is necessary to maintain the stroke length of the piston by arranging the mating surface e1 with and below the lower end of the piston at the bottom dead center of the piston.

However, when the lower part of the piston is projected from the lower end of the cylinder e, the sliding surface of the piston is shortened, which causes inconveniences such as an increase in mechanical loss and generation of a swinging sound of the piston.

Further, the position of the mating surface e1 with the crankcase can be located below by lowering the position of the mating surface e1 itself, or by extending the length of the connecting rod and raising the piston position. But the mating surface e1
Lowering the height increases the layout restrictions of the engine, which impairs the degree of freedom in design. Further, increasing the position of the piston increases the size of the engine in the vertical direction, which is not preferable for mounting the engine on the vehicle body and may increase the weight of the engine.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to ensure a sufficient sliding surface of a piston and reduce the pitch between cylinders to reduce the size of an engine. It is an object of the present invention to provide a cylinder of a multi-cylinder engine that can be reduced in weight and weight, and can be processed in a short time on a mating surface with a crankcase.

[0010]

The present invention has the following configuration to achieve the above object. That is, the present invention is a multi-cylinder engine including a crankcase in which a crankshaft is rotatably assembled therein, and a cylinder having a plurality of cylinders arranged substantially in parallel and fastened to the crankcase with fastening bolts. In the above, a bolt insertion hole through which the tightening bolt passes is provided between the cylinders adjacent to each other at a position displaced from the center line connecting the centers of the plurality of cylinders, and the plurality of cylinders include the A skirt portion protruding from the mating surface with the crankcase toward the crankshaft side and integrally formed with the cylinder during casting of the cylinder is provided, and the mating surface and the outer peripheral portion of the skirt portion are formed. A recessed surface formed by being recessed from the mating surface is provided therebetween, and the mating surface is provided with a boss of the bolt insertion hole on substantially the same plane as the mating surface. With the surface is formed, the edges of the boss seating surface located on said recessed surface is a cylinder of a multi-cylinder engine, characterized in that it is unevenly distributed closer to the bolt insertion hole side.

[0011]

According to the present invention, when the mating surface with the crankcase is machined, since the concave surface is provided around the outer peripheral portion of the skirt portion, the machining tool is separated from the skirt portion. The mating surface can be processed. At the same time, since the edge portion of the boss seating surface located on the recessed surface side is unevenly distributed near the bolt insertion hole side, it is located outside the narrow valley between the adjacent skirt portions. Come to be located. Therefore, when processing the surface of the edge portion, the diameter of the working tool can be made relatively large, and the inflection point of the moving line of the working tool can be reduced.

On the other hand, when the edge of the boss seating surface located on the concave surface side is on the peripheral edge of the normal boss seating surface, the edge is located in the narrow valley. Therefore, in order to process the boss seat surface while avoiding the outer wall of the skirt portion, the diameter of the processing tool is reduced so that the processing tool can be inserted into the narrow valley, or the diameter of the processing tool is reduced. In addition, it is necessary to move the machining tool on a line having many inflection points. Therefore, it takes time to process the mating surfaces.

Therefore, according to the present invention, the skirt portion is formed integrally with the cylinder, so that the sliding surface of the piston is sufficiently secured and the pitch between the cylinders is narrowed to miniaturize the engine. The weight can be reduced, and the mating surface with the crankcase can be machined in a short time using a machining tool having a relatively large diameter.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a bottom view of a cylinder of the multi-cylinder engine of this embodiment. FIG. 2 corresponds to FIG.
It is a II-II sectional view. FIG. 3 is a cross-sectional view of the multi-cylinder engine according to the present embodiment as viewed from the side. FIG. 4 is a sectional view of another cylinder to which the present invention is applied. Figure 5
FIG. 7 is a sectional view of still another cylinder to which the present invention is applied.

In this embodiment, as shown in FIGS. 1 to 3, a crankcase 2 in which a crankshaft 2a is rotatably assembled therein, and four cylinders # 1 and # arranged substantially in parallel.
In a parallel four-cylinder engine (an example of a multi-cylinder engine) 8 that includes a cylinder 6 that includes 2, # 3, and # 4 and is tightened to the crankcase 2 with tightening bolts. Bolt insertion holes 4 through which tightening bolts pass are provided between adjacent cylinders at positions deviated from the center line C connecting the centers, and each cylinder # 1 to # 4 includes:
From the mating surface 6a with the crankcase 2 to the crankshaft 2a
A skirt portion 6b that projects toward the side and is formed integrally with the cylinder 6 during casting of the cylinder 6 is provided, and a recess is formed from the mating surface 6a between the mating surface 6a and the outer periphery of the skirt portion 6b. The boss seat surface 4a of the bolt insertion hole 4 is formed on the mating surface 6a substantially on the same plane as the mating surface 6a, and the boss located on the dent surface 6c side is formed. Edge 10 of seat surface 4a
Are unevenly distributed near the bolt insertion hole 4 side.

The configuration of each part will be described below. As shown in FIG. 3, the parallel four-cylinder engine 8 is a four-cycle engine used in, for example, a motorcycle, and its cylinder 6 is mounted on the vehicle body with the vehicle slightly tilted forward. The engine 8 includes the cylinder 6, the crankcase 2, and a cylinder head 12 that is fastened to the upper end of the cylinder 6 and has a valve train 12a provided therein.

At the upper part of the crankcase 2, the connecting rod 1 is connected to the piston 14 which slides in each cylinder of the cylinder 6.
A crankshaft 2a connected via 6 is rotatably supported, and a transmission 18a for transmitting the power taken out by the crankshaft 2a to the lower rear portion of the crankcase 2 and adjusting the reduction ratio. There is provided a mission chamber 18 containing the above. Note that the reference numeral 20 projecting from the front surface of the crankcase 2 to the front is an oil filter, and the oil stored in the oil pan 22 at the lower portion of the crankcase 2 is the oil strainer 24.
The oil is pumped to each part of the engine by the oil pump 26. At the same time, the oil is circulated by passing through the oil filter 20 to remove metal powder and the like.

As shown in FIG. 1, the four cylinders # 1 to # 4 are arranged in parallel in a cylinder 6 in a state of being substantially circumscribed in a line, and adjacent cylinders and cylinders have a minimum necessary wall thickness. Separated by walls. A cam chain chamber 28 through which a cam chain wound between the crankshaft 2a and the camshaft of the valve operating device 12a passes is formed outside the cylinder # 4 located at the end. Further, as shown in FIG. 2, a water jacket 32 in which cooling water for cooling the cylinder 6 flows is provided inside the cylinder 6.

The bolt insertion holes 4 are provided at least in the front and rear portions between adjacent cylinders and in the front and rear portions outside the two cylinders # 1 and # 4 located at both left and right ends. The center of each bolt insertion hole 4 is located inward of the cylinder 6 so that the dimension of the cylinder 6 in the front-rear direction is as small as possible.

The outer shape of the skirt portion 6b is the crankshaft 2a.
The taper shape is such that the outer diameter gradually decreases toward the end on the side. Also, the skirt 6
The b is integrally formed with the skirt portion of the adjacent cylinder so as to be continuous in a substantially 8-shape. Therefore, the concave surface 6c formed so as to surround the outer periphery of the skirt portion 6b.
Has a shape in which two figures of eight are vertically continuous when viewed from the bottom of the cylinder, and further has a shape avoiding the boss seat surface 4 a of the bolt insertion hole 4. The mating surface 6a is a surface other than the recessed surface 6c on the lower end surface of the cylinder 6,
Moreover, the boss seat surface 4a of the bolt insertion hole 4 is included.

Then, the concave surface 6 on each boss seat surface 4a
The edge portion 10 on the c side is located inside (the center side of the bolt insertion hole 4) the peripheral edge of the other portion of the boss seat surface 4a. Along with this, the recessed surface 6c between the cylinders also widens toward the bolt insertion hole 4 side. In addition, in this embodiment, the edge portion 10 is notched so as to be unevenly distributed toward the bolt insertion hole 4 side, but the entire boss seat surface 4 a is centered with respect to the central axis of the bolt insertion hole 4. The edge portion 10 may be brought closer to the bolt insertion hole 4 side by being unevenly distributed in a direction away from C.

According to the present embodiment having the above-mentioned structure, when the mating surface 6a is machined, the concave surface 6c is provided around the outer peripheral portion of the skirt portion 6b, so that the machining tool is started from the skirt portion 6b. It is possible to process only the mating surface 6a in a state where they are separated. At the same time, since the edge portion 10 of the boss seat surface 4a located on the recessed surface 6c side is unevenly distributed near the bolt insertion hole 4 side, the edge portion 10 between the adjacent skirt portions 6b and 6b is narrower than the narrow valley. Is also located outside. Thereby, when processing the surface of the edge portion 10,
The diameter of the machining tool can be made relatively large, and the inflection point of the moving line of the machining tool can be reduced.

That is, in the conventional cylinder having no skirt portion at the time of machining the mating surface, a large-diameter machining tool can be linearly moved for machining, but in the case of this embodiment, the skirt portion 6b is cast. Since it is sometimes integrally provided, the skirt portion 6b interferes with the processing, and cannot be processed as in the conventional case. Therefore, the machining tool is moved so as to surround the skirt portion 6b with a machining tool having a small diameter to machine the mating surface. Therefore, it is necessary to reduce the number of processing steps as much as possible, and in order to reduce the number of processing steps, it is effective to reduce the inflection point of the moving line of the processing tool. In order to reduce the inflection point, it is better that the diameter of the working tool is large.

Therefore, in this embodiment, the edge portion 10 is moved to the outside of the narrow valley so that the diameter of the machining tool is as large as possible so that the inflection point of the movement line of the machining tool is reduced. For example, the mating surface 6a can be machined by moving the machining tool on a line having few inflection points as shown by an imaginary line in FIG. In this imaginary line, the line indicated by reference numeral 30c is a movement line at the center position of the machining tool, and the lines indicated by reference numerals 30a and 30b are movement lines at the inner end and the outer end of the machining tool, respectively. As shown in FIG. 1, in the present embodiment, when processing the periphery of the cylinder # 4, the diameter of the processing tool is set so that the outermost part of the cam chain chamber 28 protruding laterally can be processed at the same time. are doing.

In contrast to the present embodiment, when the edge portion of the boss seat surface 4a located on the side of the recessed surface 6c is on the peripheral edge of the normal boss seat surface 4a, the edge portion should be located in the narrow valley. Therefore, in order to process the boss seat surface 4a while avoiding the outer wall of the skirt portion 6b, the diameter of the processing tool should be reduced,
It is necessary to allow the working tool to be inserted into the narrow valley, or to reduce the diameter of the working tool and move the working tool with many inflection points. Therefore, it takes time to process the mating surfaces.

For example, in FIG. 1, if the boss seat surface 4a has a normal shape, a portion of the boss seat surface 4a located inside the moving line 30a inside the machining tool remains. Therefore, in this case, in order to remove the machining residue, it is necessary to reduce the diameter of the machining tool and move the machining tool with many inflection points.

Therefore, according to the present embodiment, since the skirt portion 6b is formed integrally with the cylinder 6, the sliding surface of the piston 14 is sufficiently secured and the pitch between the cylinders is reduced to reduce the engine. 8 can be made smaller and lighter,
Moreover, the mating surface 6a with the crankcase 2 can be machined in a short time using a machining tool having a relatively large diameter.

The present embodiment is a preferred embodiment of the present invention, and the technical scope of the present invention is not limited to this embodiment. For example, according to the present invention, as shown in FIG. 4, the cylinder 6 includes a cylinder barrel 6 that constitutes a cylinder body.
A and a sleeve 6B integrally formed by casting at the time of casting of the cylinder barrel 6A, or may be a sleeve-integrated casting type as shown in FIG. May be used for.

[0029]

As described above, according to the present invention, in the cylinder of the multi-cylinder engine, the sliding surface of the piston can be sufficiently secured, and the pitch between the cylinders can be reduced to reduce the engine size. The weight can be reduced and the mating surface with the crankcase can be processed in a short time.

[Brief description of drawings]

FIG. 1 is a bottom view of a cylinder of a multi-cylinder engine of this embodiment.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a cross-sectional view of a multi-cylinder engine according to the present embodiment as viewed from the side.

FIG. 4 is a sectional view of another cylinder to which the present invention is applied.

FIG. 5 is a sectional view of still another cylinder to which the present invention is applied.

FIG. 6 is a sectional view of a cylinder of a conventional multi-cylinder engine.

FIG. 7 is a bottom view of a cylinder of a conventional multi-cylinder engine.

FIG. 8 is a sectional view of a cylinder of another conventional multi-cylinder engine.

[Explanation of symbols]

2 crankcase 2a crankshaft 4 bolt insertion hole 4a boss seat surface 6 cylinder # 1, # 2, # 3, # 4 cylinder 6a mating surface 6b skirt portion 6c recessed surface 8 parallel four-cylinder engine (an example of a multi-cylinder engine) 10 Edge of boss seat C Center line

Claims (1)

[Claims] 1. A multi-cylinder engine comprising: a crankcase having a crankshaft rotatably assembled therein; and a cylinder having a plurality of substantially parallel cylinders, the cylinder being fastened to the crankcase with fastening bolts. A bolt insertion hole through which the tightening bolt passes is provided between adjacent cylinders at a position displaced from a center line connecting the centers of the plurality of cylinders, and the plurality of cylinders includes the crank. A skirt portion is provided which protrudes from the mating surface with the case toward the crankshaft side and is formed integrally with the cylinder during casting of the cylinder, and between the mating surface and the outer peripheral portion of the skirt portion. Is provided with a recessed surface that is recessed from the mating surface, and the mating surface is substantially flush with the mating surface and the boss seat surface of the bolt insertion hole While being formed, the edge of the boss seating surface located on said recessed surface side, the cylinder of a multi-cylinder engine, characterized in that it is unevenly distributed closer to the bolt insertion hole side.