JPH05106462A - Arrangement configuration for power unit in motor cycle - Google Patents

Abstract

PURPOSE:To make a power unit small in size by disposing a plane which passes a crank shaft and one shaft located at a high position out of a main shaft and an auxiliary shaft, in such a way as to be tilted ahead and downward, and concurrently disposing a rear fork pivot section below the plane. CONSTITUTION:In a motor cycle, a power unit PU made up of an engine E and of a transmission T is supported at the intermediate position of a car frame F, and a rear fork pivot section Fp supporting a rear wheel suspending rear fork in such a way as to be freely rocked, is disposed in rear of the power unit PU. The engine E is formed into a V-shape, and its crank shaft 2 and the input and output shafts (a main and an auxiliary shaft) 6 and 7 of the transmission T are rotatably supported by a casing 5 which is connected to the lower sections of a front and a rear cylinder block 11 and 12 while being ranged. In this case, the respective shafts 2, 6 and 7 are arranged at the apexes of a triangle when viewed from the side, a plane C including the crank shaft 2 and the shaft 6 at high positions is arranged in such a way as to be tilted ahead and downward, and a pivot Fp is disposed below the plane C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement structure of power units in a motorcycle.

[0002]

2. Description of the Related Art In a motorcycle, a rear fork pivot portion of a vehicle body frame is arranged behind a power unit having an engine and a transmission, and a crankshaft extending in a lateral direction of the engine and a crankshaft extending parallel to the crankshaft of the transmission. A structure in which a main shaft and a sub shaft are arranged in this order from the front of the vehicle toward the rear is known in the art.

[0003]

In such a conventionally known device, the three shafts of the crankshaft, the main shaft and the auxiliary shaft are arranged in parallel along one horizontal plane, which is disadvantageous in downsizing the power unit in the longitudinal direction of the vehicle body. Is.

By the way, in the above-mentioned motorcycle, when the height of the crankshaft is lowered as much as possible in order to lower the center of gravity of the engine part of the power unit, the main shaft and the sub shaft of the transmission are moved from the rear fork pivot part. It becomes considerably low. Therefore, especially in the case where the auxiliary shaft and the rear wheel shaft are transmitted by the chain transmission mechanism, for example, there is a risk of interference with the chain and the rear fork pivot shaft, and the shaft drive mechanism is used for the transmission. However, the transmission efficiency of the universal joint between the counter shaft and the drive shaft may decrease.

The present invention has been proposed in view of the above, and an object thereof is to provide an arrangement structure of power units in a motorcycle which can solve all the above-mentioned conventional problems while miniaturizing the power unit in the front-rear direction of the vehicle body as much as possible. ..

[0006]

In order to achieve the above object, the present invention provides a crank extending in the lateral direction of the engine by disposing a rear fork pivot portion in a vehicle body frame behind a power unit having an engine and a transmission. In the arrangement structure of a power unit in a motorcycle in which a shaft and a main shaft and a sub shaft parallel to the crank shaft of the transmission are arranged in this order from the vehicle direction to the rear, the crank shaft, the main shaft and the sub shaft are Arranged so that the three axes are located at the respective vertices of the triangle when viewed from the side of the vehicle body and the plane passing through the crankshaft and one of the main shaft and the auxiliary shaft at the higher position is inclined forward and downward, The rear fork pivot part is arranged below the plane.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a motorcycle will be described below with reference to the drawings. On a body frame F, a power unit PU for driving a rear wheel Wr is provided between a front wheel Wf and a rear wheel Wr. The power unit PU is supported and includes an engine E and a transmission T. Further, the body frame F is provided with a rear fork pivot portion Fp for supporting a rear fork (not shown) for rear wheel suspension so as to be vertically swingable behind the power unit PU.

In the illustrated example, the engine E is of a V type in particular.
Composed and front cylinder block 1 ₁And rear cylinder
Block 1₂have. These cylinder blocks 1
₁, 1₂Is centered on the crankshaft 2 which extends in the lateral direction of the vehicle body.
Open at a bank angle α of about 90 ° and are arranged in a V shape
Cage, each cylinder block 1₁, 1₂2 or more in
Overscare type cylinder 3₁, 3₂Is formed,
The cylinder head 4₁, 4₂Are joined
And these joint surfaces are A₁, A₂Indicate. Both cylinders
Block 1₁, 1₂At the bottom of the rear cylinder block
1₂Casing 5 extending to the rear part is integrally connected,
This casing 5 is different from the crankcase of the engine E.
It is shared with the mission case of Speed T. Thus
With the casing 5, the crankshaft 2 of the engine E,
Input shaft 6 as the main shaft of transmission T and output as the sub shaft
The shaft 7 is arranged and supported in this order from the front to the rear.
Has been.

[0009] The connecting rod 9 ₁ connected to the piston 8 ₁ of the front portion of the cylinder 3 in _1, and the connecting rod 9 ₂ leading to the piston ₈₂ of the rear portion of the cylinder 3 within ₂ be adjacent to each other, the crankshaft 2 of the common A balance weight 10 is connected to the crank pin 2a, and a balance weight 10 is attached to the crank shaft 2 on the side opposite to the crank pin 2a with the axis line as a boundary. The centrifugal force of the weight 10 is applied to both pistons 8 ₁ , 8 _2.
It is designed to balance with the primary inertial force of the system. The permissible range of the bank angle α for practically satisfying this balance is approximately 9
It is 0 ° ± 10 °.

When the crankshaft 2 and the transmission input / output shafts 6 and 7 are arranged in parallel, particularly in the illustrated example, the crankshaft 2 and the input shaft 6 are orthogonal to the straight line B dividing the bank angle α. The casing 5 is arranged on a plane C that is inclined forward and downward, and the plane C divides the casing 5 into an upper casing 5a and a lower casing 5b. Therefore, the crankshaft 2 and the input shaft 6 are supported between the split surfaces of the upper and lower casings 5a and 5b. On the other hand, the output shaft 7 is arranged behind and below the input shaft 6, and thus is supported by the lower casing 5b. A plurality of speed change gear trains 11 are provided in the casing 5 between the input and output shafts 6 and 7. Thus, the three axes of the crankshaft 2, the input shaft 6 and the output shaft 7 are located at the vertices of a triangle as seen from the side of the vehicle body as is clear from the drawing, and the casing 5, the extension As a result, the power unit PU can be miniaturized in the front-rear direction of the vehicle body.

Is an array surface of the crankshaft 2 and the input shaft 6,
And the upper and lower casings 5a and 5b are divided surfaces
The plane C is the front cylinder block 1 in the front.₁of
Cylinder 3₁Must not cross the
Also, the position of the input shaft 6 should rise excessively in the rear.
The upper surface of the rear part of the upper casing 5a is
Lock 1₂Cylinder head 4₂Joint surface A with₂Above
You have to be careful not to overhang. Young and upper
The upper surface of the rear part of the casing 5 projects and the joining surface A₂Above
If it occupies a position, its joint surface A₂When grinding the
Double block 1 ₂The upper casing 5a integrated with
As a result, the processing work becomes extremely difficult.

[0012] For this reason, in the illustrated example, especially the plane C is the front cylinder block 1 ₁ the cylinder 3 ₁ a and a rear upper surface of the upper casing 5a so as not to cross the rear cylinder block 1 ₂ cylinder head 4 ₂ The straight line B is deviated by a predetermined amount rearward from the bisector D of the bank angle α so as not to project above the joining surface A ₂ with the. That is, it should be avoided that the plane C approaches the axis of the front cylinder block 1 ₁ within β = 20 °, and within δ = 50 ° with respect to the axis of the rear cylinder block 1 _2. Since closeness should be avoided, if the position of the plane C is specifically defined from the position of the straight line B orthogonal to it so as to satisfy such a condition, the bisector D of the bank angle α to the rear cylinder it may be set the straight line B toward the block 1 ₂ side an angular range of gamma = 0 to 20 °, but in particular gamma = 10 ° before and after the best.

[0013] Thus, according to the above arrangement, each of the cylinder block 1 _1, 1 ₂ of the cylinder 3 _1, 3 ₂ of course that in the case of normal format, even if the over Scare type such as in the illustrated embodiment, the casing 5a, The inconvenience that the dividing plane C of 5b crosses the front cylinder 3 ₁ and the upper casing 5
It is possible to avoid such a disadvantage that a hinders the grinding of the joint surface A ₂ of the rear cylinder block 1 ₂ integral with the cylinder head 4 ₂ .

[0014] In a further illustrated embodiment, the clutch 12 is attached to one end of the input shaft 6, a clutch housing 13 that houses it is at one end of the casing 5 in a state of being appropriately spaced from the rear cylinder block 1 ₂ to the outer side It will be serialized. Therefore, even if the clutch 12 has a large diameter and the upper surface of the housing 13 thereof projects above the joining surface A _{2 of the} rear cylinder block 1 _{2 with} the cylinder head 4 ₂ , the housing 13 still has the large diameter.
Does not hinder the grinding of the joint surface A ₂ of the rear cylinder block 1 ₂ .

Reference numeral 14 in the drawing denotes an oil pan joined to the lower casing 5b, and its joint surface 15 is parallel to the plane C.

When the power unit PU of the illustrated example is mounted on the motorcycle M, the front cylinder block 1 ₁ of the engine E largely tilts forward and the rear cylinder block 1 also.
₂ is held in a posture such that it is substantially upright. In such a posture, the power unit PU can be compactly housed in a narrow space immediately below the fuel tank Mt, and at the same time, both cylinder blocks 1 ₁ , 1 ₂ can be cooled well by the running wind.

Further, as described above, one of the input and output shafts 6 and 7 of the transmission T located at a higher position (the input shaft 6 in the illustrated example).
By arranging the crankshaft 2 lower than that, the engine portion of the power unit PU can be made as low as possible with respect to the transmission portion, which is advantageous in achieving a low center of gravity of the engine portion. Further, even if the center of gravity of the engine portion is lowered, the rear fork pivot portion Fp is disposed lower than the plane C which is lowered frontward.
The rear fork pivot shaft (not shown) and the output shaft 7 can be arranged at the same height position as much as possible, so that the output shaft 7 and the rear wheel Wr can be transmitted by, for example, a chain transmission mechanism. However, there is no risk of interference between the chain and the pivot shaft, and there is no risk of reduction in transmission efficiency of the universal joint between the shaft and the output shaft 7 even if the shaft drive mechanism is used for transmission.

[0018]

As described above, according to the present invention, the rear fork pivot portion of the vehicle body frame is arranged behind the power unit, and the crankshaft extends in the lateral direction of the engine body and the crankshaft of the transmission. A main shaft and a sub shaft arranged in this order from the vehicle direction toward the rear, the crank shaft, the main shaft, and the sub shaft having three axes positioned at respective apexes of a triangle when viewed from the side of the vehicle body and Since the plane passing through the shaft and one of the main shaft and the auxiliary shaft at the higher position is inclined forward and downward, and the rear fork pivot portion is arranged below the plane, the crankshaft Even when the three axes of the main shaft and the auxiliary shaft are arranged in front and rear, the power unit can be miniaturized in the front-rear direction of the vehicle body by arranging them on the apexes of the triangle when viewed from the side of the vehicle body. Moreover, by arranging the crankshaft lower than the higher one of the transmission shafts, the engine part of the power unit can be made as low as possible with respect to the transmission part, which is advantageous in achieving a low center of gravity of the engine part. Is. Even by lowering the center of gravity of such an engine portion, the rear fork pivot shaft and the auxiliary shaft can be arranged at the same height position as much as possible because the rear fork pivot portion is lower than the above-mentioned plane. There is no risk that the chain will interfere with the rear fork pivot shaft even if power is transmitted by a chain transmission mechanism, and there is a risk that the transmission efficiency of the universal joint will be reduced even if power is transmitted by a shaft drive mechanism. Absent.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a motorcycle to which the present invention is applied.

[Explanation of symbols]

 C plane E engine F vehicle body frame Fp rear fork pivot part PU power unit T transmission 2 crankshaft 6 input shaft as main shaft of transmission 7 output shaft as auxiliary shaft of transmission

Claims (1)

[Claims] 1. A body frame (F) behind a power unit (PU) having an engine (E) and a transmission (T).
The rear fork pivot part (Fp) in the engine, and the crankshaft (2) extending in the lateral direction of the engine (E),
A main shaft (6) and a sub shaft (7) parallel to the crank shaft (2) of the transmission (T) are arranged in this order from the front to the rear of the vehicle body in the arrangement structure of the power unit in the motorcycle; Crankshaft (2), main shaft (6)
And the auxiliary shaft (7), the three axes (2, 6, 7) being located at the vertices of a triangle when viewed from the side of the vehicle body, and the crankshaft (2), the main shaft (6) and the auxiliary shaft (7). ), The plane (C) passing through the higher one axis (6) is arranged so as to be inclined forward and downward, and the rear fork pivot portion (Fp) is arranged below the plane (C). Characterized by having been set up,
Arrangement structure of power units in a motorcycle.