JPH0646006B2 - Crankcase for motorcycle engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a crankcase of an engine having three or more parallel cylinders that supplies lubricating oil from a main oil passage at the bottom of the crankcase to a bearing of a crankshaft.

(Prior Art) As is well known, there is a motorcycle in which an engine having three or more parallel cylinders is mounted below a vehicle body frame so as to be orthogonal to the traveling direction of the vehicle. At the bottom of the crankcase of this engine, a main oil passage is provided up to the bearings at the end of the crankshaft, and a branch oil passage for supplying oil from this main oil passage to each bearing of the crankshaft is provided. .

In this way, in the lower part of the crankcase, the bottom parts of the crankcases of both outer cylinders are in the same position as the bottom parts of the crankcases of the inner cylinders, and are the same width as the engine. The bank angle could not be increased.

Therefore, as described in Japanese Patent Application No. 58-91578, the applicant previously positions the bottom parts of the crankcases of both outer cylinders above the bottom parts of the crankcases of the inner cylinders, and An oil passage communicating with the bearing is supplied from an in-shaft oil passage in the crankshaft to provide a structure that allows a larger bank angle when the vehicle body is tilted.

By the way, although this one can take a larger bank angle, since lubricating oil is supplied to the bearings at both outer ends of the crankshaft via the in-shaft oil passages in the crankshaft,
There is a problem that the oil passage becomes long. Further, since the crankshaft rotates, the supply from the branched oil passage of the crankcase to the in-shaft oil passage of the crankshaft and the supply from the in-shaft oil passage to the bearing may not be performed smoothly.

(Object of the Invention) The present invention has been made in view of the above circumstances, and a large bank angle can be obtained, the center of gravity of the engine can be lowered, and lubricating oil can be smoothly supplied to the bearing at the outer end of the crankshaft. It is intended to provide an engine crankcase that can be supplied to.

(Structure of the Invention) In order to achieve the above object, the present invention has a main oil passage at the bottom of a crankcase, and a branch oil passage for supplying oil from this main oil passage to a bearing of a crankshaft is provided. In an engine having three or more parallel cylinders, the crankcase bottoms of both outer cylinders are arranged above the crankcase bottoms of the inner cylinders, and a branch oil passage communicating with a bearing at the outer end of the crankshaft is arranged above the crankcase. It is characterized in that the vehicle body frame is provided at the bottom of the case and below the bottom of the crankcase disposed above the case, and the main oil passage is provided at the bottom of the crankcase of the inner cylinder.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

The drawings are vertical front views showing the engine of a motorcycle to which the present invention is applied with a part thereof omitted.

In the figure, reference numeral 1 is an in-line 4-cylinder engine, and this engine 1 is mounted on a body frame 2 so as to be orthogonal to the traveling direction.

The crankcase A of the engine 1 is composed of upper and lower crankcases 3 and 4. The upper and lower crankcases 3 and 4 include five bearing support portions 3a,
4a are provided facing each other.

The crankshaft 5 has five crank journals 5a and four crankpins 5b. The crankshaft 5 has a crank journal 5a between the bearing support portions 3a and 4a,
It is rotatably provided via upper and lower bearings 6 and 7.

The upper and lower bearings 6 and 7 are formed in a semicircular shape, and the upper bearing 6 and the lower bearing 7 are press-fitted and joined to the upper bearing support 3a and the lower bearing support 4a, respectively.
A piston connecting rod 8 is rotatably provided on each of the crank pins 5b of the crank shaft 5.

A large-diameter main oil passage 9 is formed in the same direction as the crankshaft 5 in the bottom portion 4b of the lower crankcase 4, that is, the bottom portion 4b facing the two centrally located cylinders. Lubricating oil is supplied from the inlet 10 to the main oil passage 9 by the operation of an oil pump (not shown).

The main oil passage 9 is integrally formed by pulling out the core for casting when the lower crankcase 4 is cast.
After molding, the stoppers 11 are screwed into the openings at both ends. In the bearing support portion 4a which is erected on the bottom portion 4b of the lower crankcase,
A branch oil passage 12 communicating with the lower bearing 7 is bored,
Lubricating oil is supplied to upper and lower bearings 6 and 7 which pivotally support the crank journal 5a. Then, from the branch oil passages 12 of the bearing support portion 4a located on both sides of the bottom portion 4b, the in-shaft oil passage 1 further bored in the crankshaft 5
3 and is supplied to the crank pin 5b.

The lower crankcase bottoms 4c of the cylinders located on both outsides of the central cylinder are arranged above the lower crankcase bottoms 4b of the inner cylinders, and the bottoms 4c are in a state of chain double-dashed line 4
It is located a distance L above c '. A space S is secured here.

As a result, the vehicle body frame 2 is arranged in this space S, and the bank angle formed by the vehicle body center line and the vertical line due to the inclination of the vehicle body can be increased.

Then, upper and lower bearings 6 on both outer ends of the crankshaft 5,
The branch oil passage 14 communicating with 7 communicates with the branch oil passage 12 of the bearing support portion 4a inside the lower crankcase bottom portion 4c. Lubricating oil flows from the main oil passage 9 through the branch oil passage 12 to the branch oil passage 14
Is supplied to the upper and lower bearings 6 and 7 on both outer sides.

Both ends of the crankshaft 5 are closed by caps 15,
It is designed to prevent dust and water from entering from the outside. An oil pan 16 is provided below the lower crankcase bottom 4b.

Next, the operation of this embodiment will be described.

The crankshaft 5 is rotated via the connecting rod 8 by the vertical movement of the piston. This rotation of the crankshaft 5 activates an oil pump (not shown) to pump lubricating oil from the inlet 10 to the main oil passage 9.

Then, the lubricating oil is supplied from the main oil passage 9 to the upper and lower bearings 6 and 7 that pivotally support the crank journal 5a via the branch oil passages 12 and 14. Further, the lubricating oil is guided to the in-shaft oil passage 13 formed in the crankshaft 5 from the branch oil passage 12 communicating from both ends of the main oil passage 9, and is supplied to each crank pin 5b.

Then, upper and lower bearings 6 on both outer ends of the crankshaft 5,
7 is supplied from a branched oil passage 14 formed in the bottom portion 4c of the lower crankcase which is a stationary body. Therefore, the opening 14 a of the branch oil passage 14 and the supply port 7 of the lower bearing 7
There is always a fixed positional relationship with a, and a fixed amount of lubricating oil is always supplied smoothly.

Further, the lower crankcase bottoms 4c of the cylinders located on both outer sides are the lower crankcase bottoms 4b of the inner cylinders.
The vehicle body frame 2 is arranged in a space S that is arranged above and below the bottom portion 4c. As a result, the state where the vehicle body frame 2 is arranged further outside the lower crankcase bottom portion 4c 'is eliminated, the length of the lower portion of the vehicle body in the vehicle width direction can be shortened, and the bank angle due to the leaning of the vehicle body can be increased. You can

Moreover, the vehicle height from the vehicle body frame 2 to the ground can be increased, and further, when maintaining a predetermined height between the vehicle body frame 2 and the ground, the center of gravity of the entire engine can be lowered.

(Effect of the Invention) As described above, in the present invention, the crankcase bottoms of both outer cylinders are arranged above and above the crankcase bottoms of the inner cylinders in an engine having three or more parallel cylinders. Since the vehicle body frames are arranged below the bottom of the crankcase, the vehicle width of the vehicle body can be shortened, the bank angle can be increased, and the vehicle height from the vehicle body frame to the ground can be increased. The center of gravity of the entire engine can be lowered when the predetermined heights of and are maintained. A branch oil passage communicating with the bearing at the outer end of the crankshaft is provided at the bottom of the crankcase disposed above the above, so that lubricating oil is supplied from the in-shaft oil passage formed at the crankshaft to the bearing at the crankshaft end. In contrast, the oil passage is short, and the positional relationship between the inlet of the bearing and the opening of the branch oil passage does not change due to rotation and is always constant, so that lubricating oil can be supplied smoothly.

[Brief description of drawings]

The drawings are vertical front views showing the engine of a motorcycle to which an embodiment of the present invention is applied with a part of the engine omitted. 2 ... Body frame, 3 ... Upper crankcase 4 ... Lower crankcase 5 ... Crankshaft, 6 ... Upper bearing 7 ... Lower bearing, 9 ... Main oil passage 12, 14 ... Branch oil passage 13 ...... Axial oil passage

Claims (1)

[Claims] 1. A parallel three or more cylinder engine having a main oil passage at a bottom portion of a crankcase, and a branch oil passage for supplying oil from the main oil passage to a bearing of a crankshaft is arranged. The bottom of the crankcase is disposed above the bottom of the crankcase of the inner cylinder, and the branched oil passage communicating with the bearing at the outer end of the crankshaft is provided at the bottom of the crankcase disposed above the crankcase. A crankcase for an engine for a motorcycle, wherein a body frame is arranged below a bottom portion of the crankcase, and the main oil passage is provided at a bottom portion of the crankcase of the inner cylinder.