JPH0474528B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a multi-cylinder engine mounted on a vehicle.

Conventional Technology Engines for vehicles, especially road vehicles such as motorcycles and four-wheelers, require lightweight, compact multi-cylinder engines in terms of performance such as vibration, fuel efficiency, and acceleration, and various improvements have been made to date. It's here.

As an improvement of this type, there is one in which a plurality of cylinders are arranged in a staggered manner when viewed from the center direction of the cylinders, and in this configuration, the crankshafts a, a of each cylinder are at the same height as shown in Figure 1. The rotation of each crankshaft is transmitted from a crank gear b, which is integrated with these crankshafts, to a connecting gear c, which is a power extraction shaft.
The rotation of the crankshafts a, which are arranged back and forth in a staggered manner, and the main shaft integrated with the flywheel gear e, which is arranged at the same height as the crankshafts a and a, is performed through the connecting gear d and the flywheel gear e. The main shaft f and the countershaft g are equipped with a multi-stage gear group.

Problems to be Solved by the Invention However, in the above conventional technology, each crankshaft a is set at the same height, so the distance between each crankshaft in the direction perpendicular to the cylinder centerline is narrowed. In addition, the main shaft f and countershaft g, which are connected to crankshaft a and integral crank gear b via connecting gears c and d, are arranged along the same plane as crankshafts a and a. As a result, the front and rear length of the transmission case, which houses the crankcase and the large-capacity transmission gear group integrally formed behind it, has become longer.
It has been difficult to make the engine lighter and more compact.

The present invention relates to an improvement of a multi-cylinder engine that overcomes these difficulties, and its purpose is to provide a lightweight and compact multi-cylinder engine. By doing so, the crankcase and the transmission case that extends rearward integrally with the crankcase are shortened in the front-rear direction and can be arranged compactly.

Technical Means and Effects for Solving the Problems In accordance with the above object, the present invention integrally includes a transmission case that houses a transmission gear group behind the crankcase, and at least two cylinders are offset in the front-rear direction. In a multi-cylinder engine arranged in a multi-cylinder engine, the crankshaft of the rear cylinder is arranged higher than the crankshaft of the front cylinder, and the crankshaft of the front cylinder is arranged below and in front of the crankshaft of the rear cylinder. It is arranged in the front space between the power take-off shaft and the two crankshafts and the power take-off shaft form a triangle whose longest sides are the rear cylinder's crankshaft and the power take-off shaft. The rotational output from multiple crankshafts is integrated into the power take-off shaft and transmitted to the main shaft, transmission gear group, countershaft, etc. located in a relatively wide space behind the rear crankshaft and power take-off shaft. .

Embodiment An embodiment of the present invention illustrated in FIGS. 2 to 6 will be described below. 1 indicates a cylinder 2.
In a two-cycle two-cylinder gasoline engine for a motorcycle, the center lines of cylinders a and 2b are offset by X and Y in the front and back and left and right, as shown in Fig. 3, while the center lines of cylinders 2a and 2b remain parallel. Pistons 3a and 3b are respectively fitted to be slidable up and down, and the pistons 3a and 3b are connected to cranks (crankshafts) 5a and 5b in crank chambers 6a and 6b via connecting rods 4a and 4b, respectively. connected.

Among the cylinders 2, the rear cylinder 2b with respect to the front cylinder 2a is the second cylinder.
As shown in the figure, the position is set upward by Z.

In addition, as shown in FIGS. 3, 5, and 6, the crank chamber 6 has both cylinders 2a, 2b vertically arranged in parallel planes 10a, 10b along the front-rear direction passing through each center line. It is divided into three parts, each surrounded by crankcases 7, 8, and 9.

Furthermore, as shown in FIG. 3, an air supply system device 13 including a reed valve 11, which is a type of one-way valve, a carburetor 12, etc., is provided behind each of the cylinders 2, and
An exhaust system device 16 consisting of an exhaust port 14, an exhaust passage 15, etc. is arranged in front of each of the cylinders 2, and the exhaust system device 16b is arranged near the front cylinder 2a of the rear cylinder 2b, which is one cylinder. At the same time, an air supply system device 13a is arranged near the rear cylinder 2b of the front cylinder 2a, which is the other cylinder.

Furthermore, both the cylinders 2a, 2b and the crank chambers 6a, 6b are connected to the main scavenging passage 17a,
17b and sub-scavenging air passages 18a and 18b, and are designed to perform intake and exhaust operations similar to those of a normal crank case scavenging type engine, but other scavenging systems may be used.

Crank gears 19a and 19b are fitted integrally to the right side (front side in FIG. 2) of both cranks 5a and 5b at different levels, respectively, and the front crank gear 19a is a primary shaft that is a power take-off shaft. 20, and the rear crank gear 19b is connected to the second gear of the primary shaft 20 via the idle gear 24.
The crank gear 19a and the first gear 21, and the crank gear 19b and the second gear 22 are indirectly meshed and connected to the gear 22, and are formed to have the same dimensions, so that both cranks 5a and 5b have the same rotational speed. They are designed to rotate in opposite directions.

As shown in FIG. 2, the primary shaft 20 is provided below and in front of the crank 5b, and the cranks 5a, 5b and the primary shaft 20 form a triangle whose longest sides are the crank 5b and the primary shaft 20. formed,
The crank 5a is arranged in a space in front of the crank 5b and the primary shaft 20.

Further, the clutch drive gear 23 of the primary shaft 20 is meshed with a flywheel gear 25 that also serves as a flywheel.
Transmission 34 has the same center of rotation as
A multi-plate friction clutch 26 is interposed between the flywheel gear 25 and the main shaft 35, and the clutch 26 is connected to a disk 27 integral with the flywheel gear 25 and the main shaft 35. The disk 2 is integrated with a key or spline-coupled center clutch 29.
7 and a large number of disks 27 and plates 28 are connected to a center clutch 29.
A clutch lifter 30 that clamps the center clutch in cooperation with the sensor clutch 29, a coil spring 31 that presses the clutch lifter 30 against the sensor clutch 29, and a lifter rod 32 that pushes the center clutch 29 to the left (upward in the drawing) with a clutch cam 33 and disconnects the clutch. If the cam crest of the clutch cam 33 is not facing leftward (upward in the drawing) as shown in FIG. 5, the spring force of the coil spring 31 sets the clutch 26 in the connected state, When the cam ridge 33 faces leftward, the clutch 26 is set to the disconnected state.

Furthermore, the transmission 34 is equipped with a large number of gears, and the main shaft 35 and the countershaft 40 are configured to shift gear ratios in multiple stages by multi-step axial movement of gear shift forks 37 and 39 operated by two gear shafts 36 and 38. It seems like the gears are being shifted to. These gear groups are housed in a transmission case 53 that is integrally constructed with the crankcase.

Furthermore, a chain drive sprocket 41 is integrally connected to the countershaft 40, and the chain drive sprocket 41 is connected to a chain sprocket of a rear wheel (not shown) via a chain.

However, the right casing 9 (lower in the drawing)
An auxiliary cover 42 is detachably attached to cover the crank gear 19b, the second gear 22 of the primary shaft 20, and the idle gear 24.

Also, as shown in FIG. 4, the front crank 5
A rotor 44 of an alternator 43 is integrally fitted concentrically to the right side on the opposite side of the crank gear 19a.

Furthermore, a drive binion 45 is fitted concentrically to the left end of the rear crank 5b, and a pump impeller 48 is formed concentrically and integrally with a gear 46 that meshes with the drive binion 45. The impeller 48 is rotated by the rotation, and the cooling water circulation pump 47 is driven.

Since the illustrated embodiment is configured as described above, when the engine 1 is started with a starter (not shown), if the front crank 5a rotates clockwise, the rear crank 5b rotates in the opposite direction. It rotates at the same speed as the front crank 5a.

In this state, the rotational torque of the front crank 5a is applied to the crank gear 19a, the first gear 21, the primary shaft 20, and the clutch drive gear 2.
3. The transmission is transmitted to the main shaft 35 of the transmission 34 via the flywheel gear 25 and the multi-plate friction clutch 26, and is reduced to an appropriate gear ratio by the transmission 34 and transmitted to the chain sprocket 41, as shown in the figure. The rear wheel is driven through the chain that is not connected to the rear wheel chain and the rear wheel chain sprocket, and the motorcycle is able to run.

Further, the rotational torque of the rear crank 5b is transmitted to the primary shaft 20 via the crank gear 19b, the idle gear 24, and the second gear 22, and thereafter is transmitted to the rear wheel in the same manner as the torque transmission of the front crank 5a. It will be done.

Furthermore, as the engine 1 operates, the cylinders 2a, At the same time, the combustion gas in the cylinders 2a and 2b is scavenged and exhausted through the exhaust ports 14a and 14b and the exhaust passages 15a and 15b of the exhaust system devices 16a and 16b located at the front. be done.

However, as shown in FIG. 2, the cylinder 2b located at the rear by Z distance is located above the front cylinder 2a, so that the engine 1 The overall longitudinal dimension can be further reduced.

Furthermore, since the crank gear 19b is connected to the second gear 22 of the primary shaft 20 via the idle gear 24, the transmission 34
Since the main shaft 35 of the engine 1 can be moved forward, the overall dimensions of the engine 1 and transmission 34 can be made compact.

Also, planes 10a, 10b passing through the center lines of both pistons 2a, 2b and perpendicular to the crankshaft.
Since the crank chamber 6 was vertically divided into three parts, the shafts of the cranks 5a and 5b, and the primary shaft 2
0, main shaft 3 of transmission 34
5 and the countershaft 40 on the same plane, the arrangement relationship between them can be changed freely to make the engine 1 and the transmission 34 as a whole sufficiently compact, and the engine 1 can be easily machined. , an engine 1 having high rigidity despite being lightweight can be obtained.

In the embodiment described above, there are two cylinders, but it is also possible to have three or more cylinders, and in the case of an odd number, bilateral symmetry can be obtained.

Further, in the embodiment, the front crank 5a is connected to the primary shaft 20 via the crank gear 19a and the first gear 21, and the rear crank 5b is connected to the crank gear 19b and the idle gear 24.
The cranks 5a, 5b and the primary shaft 20 are connected to chain sprockets 49, 5, respectively, as shown in FIG.
0.51 and the same chain sprocket 4.
9, 50, 51 may be equipped with an endless chain 52, and in this embodiment, the crank 5
A and 5b can produce substantially the same effects as in the previous embodiment, except that both a and 5b rotate in the same direction.

In the embodiments described above, the present invention was applied to a two-stroke gasoline engine, but the present invention can also be applied to a four-stroke gasoline engine and other two- or four-stroke diesel engines.

Although the present invention has been described above in detail with respect to the embodiments shown in the drawings and the embodiments not shown in the drawings, the present invention is not limited to such embodiments and can be modified without departing from the spirit of the invention. The design can be freely modified as necessary.

Effects of the Invention In the present invention, since the crankshaft of the rear cylinder is disposed at a higher position than the crankshaft of the front cylinder, the mutual spacing between the front and rear cylinders can be further increased by deviating the crankshaft in the front-rear direction. It can be made narrower, and the structural members related to the front and rear cylinders can be integrated.
It is possible to promote lighter and more compact engines.

In addition, the power take-off shaft is provided below and in front of the crankshaft of the rear cylinder, so that the triangle formed by both crankshafts and the power take-off shaft becomes a triangle whose longest side is the line connecting the rear crankshaft and the power take-off shaft. Because of this, the space before and after the line connecting the rear crankshaft and the power take-off shaft can be used effectively, and in particular, the transmission gear group can be inserted and arranged in the wide effective space created at the rear formed by the shaft arrangement. As a result, the longitudinal length of the crankcase and the transmission case integrally connected thereto can be shortened. Since the longitudinal length of the entire engine can be shortened in this way, further compactness can be achieved.

[Brief explanation of the drawing]

Figure 1 is a longitudinal side view of a conventional multi-cylinder engine.
FIG. 2 is a longitudinal cross-sectional side view illustrating an embodiment of a multi-cylinder engine according to the present invention, and FIGS. 3 to 6 are
Figure 2 - line, - line, - line, -
FIG. 7 is a cross-sectional view taken along each line, and FIG. 7 is a longitudinal cross-sectional side view of a main part of another embodiment of the present invention. 1... Engine, 2... Cylinder, 3... Piston, 4... Connecting rod, 5... Crank, 6... Crank chamber, 7, 8, 9... Crank case, 10... Divided surface, 11... reed valve, 12... carburetor, 13... air supply system device, 14
...Exhaust port, 15...Exhaust passage, 16...Exhaust system device, 17...Main scavenging passage, 18...Sub scavenging passage, 19...Crank gear, 20...Primary shaft, 21...First gear , 22...second gear, 23...clutch drive gear, 24...
...Idle gear, 25...Flywheel gear, 2
6...Multi-plate friction clutch, 27...Disc, 2
8...Plate, 29...Center clutch, 30
...Clutch lifter, 31...Coil spring, 32...Lift rod, 33...Clutch cam, 34...Transmission, 35...Main shaft, 36...Gear shift shaft, 37
...Gear shift fork, 38...Gear shift shaft, 39...Gear shift fork, 40...
Counter shift, 41... Chain drive sprocket, 42... Auxiliary cover, 43... Alternator, 44... Rotor, 45... Drive pinion, 46... Gear, 47... Cooling water circulation pump, 48... ...Pump impeller, 49,50,5
1... Chain sprocket, 52... Endless chain, 53... Mission case.

Claims (1)

[Claims] 1. In a multi-cylinder engine that is integrally equipped with a transmission case that houses a transmission gear group at the rear of the crankcase, and that has at least two cylinders offset in the longitudinal direction, the crankshaft of the rear cylinder is connected to the front crankshaft. The crankshaft of the front cylinder is arranged at a position higher than the crankshaft of the cylinder, and the crankshaft of the front cylinder is arranged in the front space between the crankshaft of the rear cylinder and the power take-off shaft provided below and in front of it, and both crankshafts and A multi-cylinder engine characterized by a power take-off shaft forming a triangle whose longest side is the crankshaft of the rear cylinder and the power take-off shaft.