JPH071012B2 - Multi-cylinder engine - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there are various examples of a multi-cylinder engine in which at least two cylinders are arranged in front and rear, and a crank cylinder of a rear cylinder is arranged behind a crank shaft of a front cylinder. (Japanese patent publication) is shown in FIG.

The engine of the example is a three-cylinder rotary valve type two-cycle engine in which two cylinders are arranged in the front and one cylinder is arranged in the rear, and FIG. 1 is a vertical sectional side view with a part thereof omitted.

Front two-cylinder crankshaft 0
1, 02 are arranged in series, the inner ends of both crankshafts 01, 02 are connected by a power take-out gear 05, and a third crankshaft 03 is arranged in parallel behind the one crankshaft 01, An intermediate shaft 04 is juxtaposed behind the other crankshaft 02, the crankshaft 03 and the intermediate shaft 04 are arranged in series, and both inner ends are connected by a gear 06, and at the same time, the gear 06 meshes with the gear 05. are doing. The gear 07 fitted to the outer end of the intermediate shaft 04 meshes with the gear 08 of the mission section provided in the crankcase behind the intermediate shaft 04.

Therefore, the power of the three-cylinder engine is transmitted to the rear transmission via the intermediate shaft 04.

[0006]

As described above, in the case of the conventional multi-cylinder engine having front and rear crankshafts, the front crankshafts 01 and 02, the rear crankshaft 03, and the transmission are arranged in order from the front in the crankcase. As a result, the front-rear length of the crankcase including the transmission is increased, which hinders downsizing of the engine.

The present invention has been made in view of the above points, and an object of the present invention is to provide a multi-cylinder engine in which the front and rear length of a crankcase can be shortened to make the engine compact.

[0008]

In order to achieve the above object, the present invention has at least two cylinders arranged in front and rear, and a crankshaft of a rear cylinder arranged behind a crankshaft of a front cylinder. Then, in a multi-cylinder engine in which a transmission is arranged in a crankcase that houses the front and rear crankshafts, the crankshaft of the rear cylinder is arranged at a higher position than the crankshaft of the front cylinder, and At least a part of the transmission is a multi-cylinder engine arranged below the crankshaft of the rear cylinder.

Since at least a part of the transmission is disposed below the crankshaft of the rear cylinder, which is higher than the crankshaft of the front cylinder, the transmission is adjacent to the front cylinder without the rear cylinder. The front and rear length of the crankcase can be shortened.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 2 to 6 will be described below. As shown in FIG. 3, the reference numeral 1 indicates the front and rear and the front and rear of the cylinders 2a and 2b while keeping the center lines parallel to each other. A two-cycle two-cylinder gasoline engine for motorcycles that is offset left and right by X and Y. Pistons 3a and 3b are vertically slidably fitted in the cylinders 2a and 2b, respectively, and the pistons 3a and 3b are connected. It is connected to each crank 5a, 5b in the crank chambers 6a, 6b via rods 4a, 4b.

However, among the cylinders 2, the rear cylinder 2b with respect to the front cylinder 2a is set at a position higher by Z upward as shown in FIG. Further, as shown in FIGS. 3, 5 and 6, the crank chamber 6 is vertically divided into three parallel surfaces 10a and 10b passing through the center lines of the cylinders 2a and 2b and extending in the front-rear direction. It is divided into 7, 8, and 9.

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

Further, the both cylinders 2a, 2b and the crank chambers 6a, 6b are communicated with each other through the main scavenging passages 17a, 17b and the sub-scavenging passages 18a, 18b. The intake and exhaust operations are similar to the above, but other scavenging methods may be used.

However, the crank gears 19a, 19 are arranged on the right side (the front side in FIG. 2) of the both cranks 5a, 5b in different stages.
b are fitted together, and the front crank gear 19a
Is directly meshed and coupled to the first gear 21 of the primary shaft 20, and the rear crank gear 19b is indirectly meshed and coupled to the second gear 22 of the primary shaft 20 through the idle gear 24, so that the crank gear 19a and the first gear are connected. 21, the crank gear 19b and the second gear 22 are formed to have the same size, so that both cranks 5a and 5b rotate in the opposite directions at the same rotation speed.

The clutch drive gear 23 of the primary shaft 20 is also a flywheel gear that also functions as a flywheel.
25, the main shaft 35 of the transmission 34 is pivotally supported at the same rotation center as the flywheel gear 25, and the multi-plate friction clutch 26 is interposed between the flywheel gear 25 and the main shaft 35. The clutch 26 includes a disc 27 integrated with the flywheel gear 25, and a main shaft.
Center clutch 29 keyed or splined to 35
A plate 28 integrally disposed between the disks 27,
Center clutch 29 with multiple discs 27 and plates 28
Clutch lifter 30 that clamps in cooperation with and a coil spring that presses the clutch lifter 30 against the center clutch 29.
31 and a lifter rod 32 that pushes the center clutch 29 to the left (upward in the drawing) with the clutch cam 33 to disconnect the clutch.
When the cam crest of the clutch cam 33 does not face leftward (upward in the drawing) as shown in FIG.
Is set to the connected state, and when the cam crest of the clutch cam 33 is directed to the left, the clutch 26 is set to the disengaged state.

Further, in the transmission 34, the gearshift forks 37, 39 operated by the two gearshift shafts 36, 38 are moved in a multi-step axial direction, whereby the main shaft 35 is moved.
The counter shaft 40 and the counter shaft 40 are switched to a multistage gear ratio. This transmission 34
Is in the crankcase forming the crank chamber 6.

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

Therefore, an auxiliary cover 42 is detachably attached to the right casing 9 (downward in the drawing) so as to cover the crank gear 19b, the second gear 22 of the primary shaft 20 and the idle gear 24. Has become.
Further, as shown in FIG. 4, the front crank 5a is integrally and concentrically fitted with the rotor 44 of the AC generator 43 on the opposite right side with the crank gear 19a interposed therebetween.

Since the illustrated embodiment is constructed as described above, when the engine 1 is started by a starter (not shown), when the front crank 5a rotates, for example, clockwise, the rear crank 5b becomes Crank forward in the opposite direction
It rotates at the same speed as 5a.

In this state, the rotational torque of the front crank 5a is transmitted through the crank gear 19a, the first gear 21, the primary shaft 20, the clutch drive gear 23, the flywheel gear 25, and the multiple disc friction clutch 26 to the transmission 34. Is transmitted to the main shaft 35 of the vehicle, is transmitted to the chain sprocket 41 after being decelerated to an appropriate gear ratio by the transmission 34, and the rear wheel is driven through the chain and the rear wheel chain sprocket (not shown) to allow the motorcycle to run. Become.

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,
It is transmitted to the rear wheel in the same manner as the torque transmission of the front crank 5b.

Further, along with the operation of the engine 1, the carburetor 12a and the reed valve 11 of the rear air supply system devices 13a and 13b.
a, 11b, crank chambers 6a, 6b and scavenging passages 17a, 17
The air-fuel mixture is sucked into the cylinders 2a, 2b via b, 18a, 18b, respectively, and the combustion gas in the cylinders 2a, 2b is scavenged, so that the exhaust system device 16a located in front of
16b exhaust ports 14a, 14b and exhaust passages 15a, 15b
Is discharged through.

When the cranks 5a and 5b are connected to the primary shaft 20 in the phase relationship shown in FIG. 2, the crankshafts rotate in opposite directions, so that the front and rear cylinders 2a of the respective front and rear cylinders 2a. , 2b, the rotational vibrations in the front-rear direction cancel each other out to reduce the vibration of the entire engine, which can improve the performance of the engine and reduce the thickness of the crankcase. Together with the arrangement, the engine can be made even lighter and more compact.

Further, in the above-described embodiment, the two cylinders 2a and 2b are arranged in a zigzag pattern on the front, rear, left and right as shown in FIG. 3, so that the front, rear, left and right dimensions of the entire engine 1 can be reduced. .

Further, as shown in FIG. 2, since the cylinder 2b rearward by Z is positioned above the front and rear cylinders 2a, the front-rear dimension of the entire engine 1 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 and the main shaft 35 of the transmission 34 is arranged below the crank 5b, the transmission 34 is moved forward to the crank 5b. Since they can be adjacent to each other, the front and rear lengths of the crankcase can be shortened, and the overall dimensions of the engine 1 and the transmission 34 can be made compact.

Further, the front crank gear 19a is meshed with the first gear 21 of the primary shaft 20, and the rear crank gear 19b is meshed with the second gear 22 of the primary shaft 20 via the idle gear 24, and the outside thereof. Auxiliary cover
Since 42 is covered, if the auxiliary cover 42 is removed and the idle gear 24 is removed, the crank angle of the front cylinder 2a and the crank angle of the rear cylinder 2b can be appropriately changed. You can easily change the explosion timing of 2b.

Further, since the crank chamber 6 is vertically divided into three parts by planes 10a and 10b which pass through the center lines of both pistons 2a and 2b and are perpendicular to the crankshaft, the shafts of the cranks 5a and 5b, the primary shaft 20, and the transmission 34 It is not necessary to position the main shaft 35 and the counter shaft 40 of the same plane on the same plane, and it is possible to freely change the positional relationship between the main shaft 35 and the counter shaft 40 to make the whole of the engine 1 and the transmission 34 compact enough, and to process the engine 1 It is possible to obtain the engine 1 which is simple and lightweight but has high rigidity.

In the above-mentioned embodiment, the number of cylinders is two, but the number of cylinders can be three or more, and in the case of an odd number, left-right symmetry can be obtained.

Although the present invention is applied to the two-cycle gasoline engine in the above-mentioned embodiment, the present invention can be applied to the four-cycle gasoline engine and other two or four-cycle diesel engine.

[0031]

As described above, the present invention has at least 2
Since multiple cylinders are constructed by arranging cylinders in the front and rear and in the top and bottom, the front and rear dimensions of the engine can be shortened and the structural members related to the front and rear cylinders can be integrated. In addition, since the multi-cylinder engine has a structure in which at least a part of the transmission is arranged below the rear crankshaft, which is located higher than the front crankshaft, the transmission is adjacent to the front crankshaft and the crankcase itself. The front-rear length of the engine can be shortened, and the engine can be further reduced in weight and size.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a conventional multi-cylinder engine.

FIG. 2 is a vertical sectional side view showing an embodiment of a multi-cylinder engine according to the present invention.

FIG. 3 is a cross-sectional view taken along the line III-III of FIG.

FIG. 4 is a cross-sectional view cut along the line IV-IV in FIG.

5 is a cross-sectional view taken along the line VV of FIG.

6 is a transverse cross-sectional view cut along the line VI-VI in FIG.

[Explanation of symbols] 1 ... Engine, 2 ... Cylinder, 3 ... Piston, 4 ... Connecting rod, 5 ... Crank, 6 ... Crank chamber,
7, 8, 9 ... Crankcase block, 10 ... Dividing surface, 11
... Reed valve, 12 ... Vaporizer, 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, 26 ... Multi-disc friction clutch, 27 ... Disc, 28
... Plate, 29 ... Center clutch, 30 ... Clutch lifter, 31 ... Coil spring, 32 ... Lifter 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.

Claims (1)

[Claims] 1. At least two cylinders are arranged in front and rear, a crankshaft of a rear cylinder is arranged behind a crankshaft of a front cylinder, and a transmission is arranged in a crankcase accommodating the front and rear crankshafts. In the installed multi-cylinder engine, the crankshaft of the rear cylinder is arranged at a higher position than the crankshaft of the front cylinder, and at least a part of the transmission is arranged below the crankshaft of the rear cylinder. A multi-cylinder engine that is characterized by