JP3290624B2 - Parallel two-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a crankcase divided into two in the axial direction of a crankshaft, and a cylinder block having a pair of cylinder bores. The cylinder block is formed by a plurality of bolts extending parallel to the cylinder bores. The present invention relates to a parallel two-cylinder engine coupled to a crankcase.

[0002]

2. Description of the Related Art Such a parallel two-cylinder engine is used, for example, for a power unit of a motorcycle. Generally, in a parallel two-cylinder engine of this type, a split surface of a left half of the crankcase and a split surface of a right half of the crankcase are formed by an intermediate surface of a pair of cylinder bores formed in a cylinder block (equal to the axis of both cylinder bores). (A plane at a distance).

[0003]

By the way, in the prior art described above, when the bolts for connecting the cylinder block to the crankcase are to be arranged on the intermediate plane between the two cylinder bores, the bolts are moved to the left half of the crankcase and the right of the crankcase. There is a problem that the screw cannot be screwed in due to interference with the half divided surface. Therefore, conventionally, bolts for connecting the cylinder block to the crankcase are arranged on the left and right sides of the intermediate surface, respectively, to prevent the bolts from interfering with the divided surfaces of the left half of the crankcase and the right half of the crankcase. Was.

However, if the bolts are arranged on the left and right sides of the intermediate surface of the pair of cylinder bores, the interval between the pair of cylinder bores is inevitably widened in order to secure a space for the bolts, which increases the size of the engine. There is a problem that can be a factor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to reduce the size of a pair of cylinder bores of a parallel two-cylinder engine as much as possible in the axial direction of the crankshaft. I do.

[0006]

In order to achieve the above object, the invention described in claim 1 comprises a crankcase divided into two in the axial direction of a crankshaft and a cylinder block having a pair of cylinder bores. In a parallel two-cylinder engine in which a cylinder block is connected to a crankcase with a plurality of bolts extending in parallel with the cylinder bore, the split surface of the crankcase is arranged in the axial direction of the crankshaft with respect to the intermediate surface of the pair of cylinder bores. One of the plurality of bolts, which is disposed near the intermediate surface of the cylinder bore, is screwed into the crankcase while avoiding the dividing surface.

[0007] According to the above configuration, since the divided surface of the crankcase is deviated in one of the axial directions of the crankshaft with respect to the intermediate surface of the pair of cylinder bores, when the cylinder block is connected to the crankcase with bolts. A bolt arranged near the intermediate surface of the pair of cylinder bores,
It can be screwed into the crankcase without interfering with the dividing surface. As a result, it is possible not only to generate a uniform fastening force without increasing the number of bolts, but also to reduce the size of the engine in the axial direction by bringing the pair of cylinder bores closer together, and The area of the coupling surface between the crankcase and the cylinder block can be reduced to enhance the sealing performance.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the crankshaft includes a pair of journals on both sides of a pair of cylinder bores, and the crankshaft is formed by dividing the pair of journals into two. It is characterized by being supported by each of the cases.

According to the above configuration, since the crankshaft is supported by the crankcase by the pair of journals provided on both sides of the pair of cylinder bores, the central journal of the crankshaft is eliminated and the pair of cylinder bores is reduced as much as possible. The size of the engine can be further reduced by approaching.

According to a third aspect of the present invention, in addition to the first aspect, a cam driving means for transmitting a driving force of a crankshaft to a camshaft provided on a cylinder head is provided. It is characterized by being arranged at one end in the axial direction.

According to the above structure, it is not necessary to arrange the cam driving means for transmitting the driving force of the crankshaft to the camshaft at an intermediate position between the pair of cylinder bores. Further downsizing can be achieved. In addition, since the cam driving means is disposed at one end of the crankcase and the cylinder block in the axial direction, the dimensions of each half of the crankcase divided into two on the division surface are equalized to facilitate manufacture. be able to. Further, according to the fourth aspect,
In addition to the configuration of claim 3, the shaft of the camshaft
The cam located at the other end in the linear direction is cantilevered
It is characterized by being.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 3 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a parallel two-cylinder engine, and FIG.
3 is a cross-sectional view taken along line 2-2 of FIG. 1, and FIG. 3 is a cross-sectional view taken along line 3-3 of FIG.

A parallel two-cylinder engine E for a motorcycle shown in FIG. 1 is mounted on a vehicle body (not shown) with its crankshaft 1 arranged in the left-right direction. The crankcase 2 of the engine E moves in the direction of the axis L of the crankshaft 1.
Composed of split crankcase left half 3 is coupled in the first dividing plane P ₁ and _L and crankcase right half 3 _R. Cylinder block 4 which is inclined to the vehicle body before the upper is coupled to the second divided surface P _2, which is formed so as to extend over the crankcase left half 3 _L and the crankcase right half 3 _R, the upper surface of the cylinder block 4 The cylinder head 5 and the head cover 6 are further coupled.

[0015] Crankshaft 1 pair of left and right journal 7 _L, 7 _R, they journal 7 _L, 7 pair of pins 8 located inside the _{R L,} 8 and a _R, left journal 7 _L There while being supported on the journal support portions 9 _L provided in the crankcase left half 3 _L, right journal 7 _R is supported by the journal supporting part 9 _R provided in the crankcase right half 3 _R. Crankshaft 1
Is covered with a generator cover 12 fixed to the left half 3 _L of the crankcase with bolts 11. Also the right half of the crankcase 3
_A starting clutch (not shown) is housed inside a clutch cover 14 fixed to _R with bolts 13.

A pair of left and right cylinder bores 15 _L , 15 _R are arranged side by side inside the cylinder block 4, and the piston 1 is slidably fitted into each of the cylinder bores 15 _L , 15 _R.
6 _L and 16 _R are connected rod 1
7 _L , 17 _R via the pin 8 _{L of} the crankshaft 1,
Connected to 8 _R. At the right end of the crankshaft 1, an input gear 19 for transmitting a driving force to a transmission 18, a balancer shaft driving gear 20, a camshaft driving sprocket 21, and a rotor 22 for detecting the phase of the crankshaft 1 are fixed. You. An outer peripheral portion of the rotor 22 faces an electromagnetic pickup 23 fixed to an inner surface of the clutch cover 14.

Referring to FIG. 2 together, it is apparent that
Camshaft support portions 5 ₁ which is formed in the cylinder head 5,
5 _1, 5 ₂ , 5 ₂ ; 5 ₃ , 5 ₃ and an intake cam shaft 43 i and an exhaust cam shaft 43 o are rotatably supported between a cam shaft holder 42 connected to the cylinder head 5 with bolts 41. Is done. Intake camshaft 4
3i and camshaft driven sprockets 44i, 44o provided at the right ends of the exhaust camshaft 43o, respectively.
Is connected to the camshaft driving sprocket 21 via an endless chain 45 housed in an endless chain chamber 40 vertically penetrating the crankcase 2, the cylinder block 4 and the cylinder head 5. The endless chain 45 constitutes the cam driving means of the present invention. The number of teeth of the camshaft driven sprockets 44i, 44o is set to be twice the number of teeth of the camshaft driving sprocket 21. Therefore, the intake camshaft 43i per two rotations of the crankshaft 1
The exhaust camshaft 43o makes one rotation.

The intake camshaft 43i is provided with four intake cams 46i.
6i are provided in each cylinder, two intake valves 47i.
Contact the stem end of ... Also the exhaust camshaft 4
3o are provided with four exhaust cams 46o. These four exhaust cams 46o contact the stem ends of two exhaust valves 47o provided in each cylinder.

As is apparent from FIG.
Crankcase left half 3 _L and the crankcase right half 3 _R coupled in the first dividing plane P ₁ is screwed into the crankcase right half 3 _R is inserted from the crankcase left half 3 _L side Are fixed together by a plurality of bolts 48. One of the plurality of bolts 48 is shown in FIG.
And two are shown in FIG.

The cylinder block 4 coupled to the second divided surface P ₂ of the crank case 2, is bolted 49 _{1-49 8} eight with the cylinder head 5. Two bolts 49 ₇ and 4 of the _eight bolts 49 ₁ to 498 are used.
9 ₈ penetrates from top to bottom right end of the cylinder head 5 and the cylinder block 4, is screwed into the second divided surface P ₂ of the crankcase right half 3 _R. The other six bolts 49 ₁
To 49 ₆ consists previously screwed to the stud bolt to the second divided surface P ₂ of the crankcase 2, a cylinder block 4 and the cylinder head 5 is cap nut 50 fitted therein
Are fastened from above. In this case, two bolts 49 _3, 49 ₄ by fitting the collar 51 that penetrate into both of the crankcase 2 and the cylinder block 4, the crankcase 2 and the cylinder block 4 is positioned to one another. Further to supply lubricating oil to the cylinder head 5 from the crankcase 2 through the cylinder block 4, the oil passage 52, 53, 54 to one volt 49 ₆ outer periphery of the second divided surface P ₂ of the crankcase 2 It is formed.

As is apparent from FIGS. 1 and 3, a pair of cylinder bores 15 _L, 15 intermediate plane of _R C (surface equidistant from the axis of the pair of cylinder bores 15 _L, 15 _R)
Are biased only in the left direction by a distance D with respect to the first dividing plane P ₁ of the crankcase left half 3 _L and the crankcase right half 3 _R. In other words, both cylinder bores 15 _L , 1
Against 5 _R intermediate plane C of the first divided surface P ₁ of the crankcase left half 3 _L and the crankcase right half 3 _R is offset to the right direction by a distance D. Therefore, the eight bolts 49 ₁ connecting the cylinder block 4 to the crankcase 2
To 49 of the _8, both the cylinder bore 15 _L, 15 _R intermediate plane C being arranged on two bolts 49 _3, 49 _4, crankcase left half 3 without interfering with the first divided surface P _{1 It} can be screwed into _L.

It is assumed that both cylinder bores 15_L, 15_Rin
Intermediate face C and left half of crankcase 3 _LAnd Crankke
Right half 3_RFirst division plane P₁Are on the same plane
And the first division plane P₁The intermediate plane C to interfere with
Bolt 49 on top_Three, 49_FourCan no longer be placed
You. Therefore, both cylinder bores 15_L, 15_RIntermediate plane C
Two bolts each on the left and right side of the
The number of bolts required as a result
As well as make room for those bolts
To use both cylinder bores 15_L, 15_RNeed to increase the interval between
Therefore, the dimension of the engine E in the direction of the axis L is
There is a problem that it becomes large.

However, according to the present embodiment, the intermediate plane C of the two cylinder bores 15 _L and 15 _R and the first divided plane P of the crankcase left half 3 _L and the crankcase right half 3 _R.
By that biases the ₁ and, by placing the two bolts 49 ₃ on the intermediate plane C, 49 _4, both the cylinder bores 15
_L, 15 on the second divided surface P ₂ in the vicinity of _R not only can generate a left and right equal clamping forces, both cylinder bores 15 _L, 15 the axis of narrowing the distance _R as much as possible the engine E L The size in the direction can be reduced. Furthermore, since the smaller the second dividing plane P ₂ by the miniaturization of the axis L direction of the dimension of the engine E, also facilitates securing the sealability of the second divided surface P _2.

The crankshaft 1 is provided at both ends.
A pair of journals 7_L, 7_RTo support crankcase 2
Jar in the center of the crankshaft 1
And the journal supporter who supports the journal
Can be abolished, so that both cylinder bores 15
_L, 15_ROf the engine E in the direction of the axis L of the engine E
Not only can the size of the
It is possible to increase the rigidity by downsizing the link shaft 1 itself.
Wear. Similarly, an intake cam shaft 43i and an exhaust cam
Crank endless chain 45 that drives shaft 43o
Placed at the ends of case 2 and cylinder block 4
With this, both cylinder bores 15_L, 15 _RNarrow the interval between
Thus, the size of the engine E can be reduced.

[0025] While the right surface of the crankcase 2 and the cylinder block 4 has overhanging endless chain chamber 40, the first divided surface P ₁ of the crankcase left half 3 _L and the crankcase right half 3 _R is, Double cylinder bore 1
On the right side of the 5 _L, 15 _R intermediate plane C of, ie, is offset to the endless chain chamber 40 side, and the dimension W _L of the axis L direction of the crank case left half 3 _L, crankcase right half The dimension W _{R of the} 3 _{R in} the direction of the axis L can be made uniform. As a result, it is possible to prevent one of the two halves 3 _L and 3 _{R from} becoming large, to reduce the size of the die for die casting, and to reduce the manufacturing cost.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, two bolts 49 ₃ ,
49 ₄ of the pair cylinder bores 15 _L, 15 intermediate plane of _R C
Although arranged above be placed them bolts 49 _3, 49 ₄ in the vicinity of the intermediate plane C can be obtained the same effect. In the embodiment, a pair of cylinder bores 1
The middle plane C of 5 _L and 15 _R is 3 _{L of the} left half of the crankcase.
And although biased in the left direction with respect to the first dividing plane P ₁ of the crankcase right half 3 _R, it is possible to bias it in the right direction. The number of bolts arranged near the intermediate surface C is not limited to two, and the bolts need not be stud bolts.

[0028]

As described above, according to the first aspect of the present invention, the split surface of the crankcase is deviated in the axial direction of the crankshaft with respect to the intermediate surface between the pair of cylinder bores. When connecting the cylinder block to the crankcase with bolts, the bolts arranged near the intermediate surfaces of the pair of cylinder bores can be screwed into the crankcase without interfering with the divided surfaces. As a result, it is possible not only to generate a uniform fastening force without increasing the number of bolts, but also to reduce the size of the engine in the axial direction by bringing the pair of cylinder bores closer together, and The area of the coupling surface between the crankcase and the cylinder block can be reduced to enhance the sealing performance.

According to the invention described in claim 2,
Since the crankshaft is supported by the crankcase with a pair of journals provided on both sides of the pair of cylinder bores,
The journal at the center of the crankshaft is eliminated, and the pair of cylinder bores can be made as close as possible to further reduce the size of the engine.

According to the third aspect of the present invention,
Since there is no need to arrange a cam driving means for transmitting the driving force of the crankshaft to the camshaft at an intermediate position between the pair of cylinder bores, the two cylinder bores can be made as close as possible to further reduce the size of the engine. . In addition, since the cam driving means is disposed at one end of the crankcase and the cylinder block in the axial direction, the dimensions of each half of the crankcase divided into two on the division surface are equalized to facilitate manufacture. be able to.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a parallel two-cylinder engine.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

[Explanation of symbols]

1 crankshaft 2 crankcase 4 cylinder block 5 a cylinder head 7 _L, 7 _R journal 15 _L, 15 _R cylinder bore 43 i, 43 o camshaft 45 endless chain (cam drive means) 46i, 46o cam 49 _{1-49 8} volt C Intermediate plane L axis P ₁ First division plane (division plane)

Claims (4)

(57) [Claims] And 1. A axis (L) direction 2 divided crankcase of the crankshaft (1) (2), a cylinder block (4) having a pair of cylinder bores (15 _L, 15 _R), the the cylinder bore (15 _L, 15 _R) in a parallel two-cylinder engine formed by combining parallel extending a plurality of bolts (49 ₁ to 49 ₈₎ in the cylinder block (4) in the crankcase (2), a crankcase (2 splitting surface of) (P ₁₎ with biasing on one axis (L) direction of the crankshaft (1) with respect to a pair of cylinder bores (15 _L, 15 _R) the intermediate surface of (C), of the plurality of bolt the cylinder bore of the _{(49 1 ~49 8) (15} L, 15 R) of the intermediate plane (C) a bolt disposed in the vicinity of (49 _3, 49 ₄₎
And avoiding the dividing plane (P ₁₎ crankcase (2)
A parallel two-cylinder engine which is screwed into the engine. Wherein said crankshaft (1) is provided with a pair of journals (7 _L, 7 _R) on both sides of the pair of cylinder bores (15 _L, 15 _R), those a pair of journals (7 _L, 7 _R The parallel two-cylinder engine according to claim 1, wherein each of the crankcases (2) is supported by each of two divided crankcases (2). 3. A cam drive means (45) for transmitting a driving force of a crankshaft (1) to camshafts (43i, 43o) provided on a cylinder head (5) comprises a crankcase (2) and a cylinder block (4). ) At one end in the direction of the axis (L).
The parallel two-cylinder engine according to claim 1. (4) The camshaft (43i, 43o)
A cam (46i, 46i) located at the other end in the axis (L) direction.
46o) is characterized by being cantilevered,
The parallel two-cylinder engine according to claim 3.