JPH04350329A - Multicylinder engine - Google Patents

Abstract

PURPOSE:To provide a structure of a multicylinder engine in which the reductions in weight and size of the engine can be achieved. CONSTITUTION:At least two cylinders 2a, 2b are aranged in front and in rear, and a crankshaft 5b of the rear cylinder 2b is arranged in the rear of a cranks shaft 5a of the front cylinder 2a. In the multicylinder engine in which a transmission 34 is arranged and installed in a crank case for containing the front and rear crankshafts 5a, 5b, the crank shaft 5b of the rear cylinder 2b is arranged at a higher position compared to the crank shaft 5a of the front cylinder 2a, and at least a part of the variable speed gear 34 is arranged below the crankshaft 5b of the rear cylinder 2b.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a multi-cylinder engine.

0002

[Prior Art] There have been various examples of multi-cylinder engines in which at least two cylinders are arranged one behind the other, and the crankshaft of the rear cylinder is arranged behind the crankshaft of the front cylinder.
241) is shown in FIG.

The engine of this example is a three-cylinder rotary valve type two-stroke engine with two cylinders in the front and one cylinder in the rear, and FIG. 1 is a partially omitted vertical sectional side view of the engine.

[0004] Front 2 cylinder crankshaft 0
1 and 02 are arranged in series, and both crankshafts 01 and 0
The inner ends of the two crankshafts 02 are connected by a gear 05 for power extraction, a third crankshaft 03 is arranged in parallel behind the one crankshaft 01, and an intermediate shaft 04 is arranged in parallel behind the other crankshaft 02. A crankshaft 03 and an 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. A gear 07 fitted to the outer end of the intermediate shaft 04 meshes with a gear 08 of a transmission section provided in the crankcase behind it.

[0005] Therefore, the power of the three-cylinder engine is transmitted to the rear transmission via the intermediate shaft 04.

[0006]

[Problems to be Solved] As described above, in the case of a conventional multi-cylinder engine with crankshafts arranged at the front and rear, the front crankshafts 01, 02,
Since the rear crankshaft 03 and the transmission are arranged in order from the front, the front-rear length of the crankcase including the transmission becomes long, which is an obstacle to making the engine more compact.

[0007] The present invention has been devised in view of the above points, and its object is to provide a multi-cylinder engine which can be made more compact by shortening the longitudinal length of the crankcase.

[0008]

[Means and Operations for Solving the Problems] In order to achieve the above object, the present invention provides at least two cylinders arranged one behind the other, with the crankshaft of the rear cylinder arranged behind the crankshaft of the front cylinder. In the multi-cylinder engine in which a transmission is disposed in a crankcase housing the front and rear crankshafts, the crankshaft of the rear cylinder is disposed at a higher position compared to the crankshaft of the front cylinder, and the At least a part of the transmission is a multi-cylinder engine disposed below the crankshaft of the rear cylinder.

At least a portion of the transmission is disposed below the crankshaft of the rear cylinder, which is located higher than the crankshaft of the front cylinder, so the transmission is adjacent to the front cylinder without intervening the rear cylinder. This allows the front and rear length of the crankcase to be shortened.

0010

[Embodiment] An embodiment of the present invention shown in FIGS. 2 to 6 will be described below. 1 indicates cylinders 2a and 2b.
As shown in Figure 3, while the center lines of
This is a two-stroke, two-cylinder gasoline engine for motorcycles that is offset by X and Y in the front and rear and left and right.
Pistons 3a and 3b are fitted into the crankshafts 2b so as to be slidable up and down, respectively, and the pistons 3a and 3b are connected to cranks 5a and 5b in crank chambers 6a and 6b via connecting rods 4a and 4b, respectively. .

Among the cylinders 2, the rear cylinder 2b with respect to the front cylinder 2a is set upwardly at a higher position by Z, as shown in FIG. Further, the crank chamber 6 is shown in FIGS. 3, 5, and 6.
As illustrated in FIG.
It is vertically divided into three parts 7, 8, and 9.

Furthermore, as shown in FIG. 3, an air supply system device 13 consisting of a reed valve 11, which is a type of one-way valve, a carburetor 12, etc., is provided at the rear of each of the cylinders 2. , an exhaust system device 16 consisting of an exhaust port 14, an exhaust passage 15, etc. is arranged in front of each of the two cylinders 2, and the exhaust system device 16b is located closer to 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 crank chambers 6a, 6b are main scavenging passages 17a, 1
7b and sub-scavenging passages 18a and 18b, and performs intake and exhaust operations similar to those of a normal crank case scavenging type engine, but other scavenging systems may be used.

[0014] However, the crank gear 19 is located on the right side of the cranks 5a and 5b (on the near side in Fig. 2) with different levels.
a and 19b are fitted together, and the front crank gear 19a is connected to the first gear 21 of the primary shaft 20.
The rear crank gear 19b is connected to the second primary shaft 20 via the idle gear 24.
The crank gear 19a is indirectly connected to the gear 22 and connected to the crank gear 19a.
The first gear 21, the crank gear 19b, and the second gear 22 are formed to have the same dimensions, so that the cranks 5a and 5b rotate in opposite directions at the same rotational speed.

The clutch drive gear 23 of the primary shaft 20 is meshed with a flywheel gear 25 which also serves as a flywheel, and a main shaft 35 of a transmission 34 is pivotally supported around the same rotation center as the flywheel gear 25. A multi-disc friction clutch 26 is interposed between the wheel gear 25 and the main shaft 35, and the clutch 26 is integrated with a disk 27 that is integrated with the flywheel gear 25, and a center clutch 29 that is connected to the main shaft 35 by a key or spline. and said disk 2
7 and a large number of disks 27
A clutch lifter 30 that clamps the plate 28 in cooperation with the center clutch 29, a coil spring 31 that presses the clutch lifter 30 against the center clutch 29, and a clutch cam 33 to move the center clutch 29 to the left (upward in the drawing). Lifter rod 3 that pushes out to disconnect the clutch
2, and the cam crest of the clutch cam 33 is shown in Figure 5.
When the clutch cam 33 is not facing leftward (upward in the drawing) as shown in the figure, the clutch 26 is set to the connected state by the spring force of the coil spring 31, and when the cam crest of the clutch cam 33 is facing leftward, , the clutch 26 is set to a disconnected state.

Furthermore, the transmission 34 has two
The main shaft 35 and countershaft 40 are configured to be shifted to multiple speed ratios by multi-step axial movement of gear shift forks 37, 39 operated by real gear shift shafts 36, 38. This transmission 34 is located within a crankcase forming the crank chamber 6.

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.

[0018]The right casing 9 (lower in the drawing) has a crank gear 19b and a primary shaft 20.
so as to cover the second gear 22 and idle gear 24 of
The auxiliary cover 42 is designed to be removably attached. Further, as shown in FIG. 4, the front crank 5a has an alternator 43 on the right side opposite to the crank gear 19a.
The rotor 44 is fitted concentrically.

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

In this state, the rotational torque of the front crank 5a is transmitted to the transmission 34 via the crank gear 19a, the first gear 21, the primary shaft 20, the clutch drive gear 23, the flywheel gear 25, and the multi-disc friction clutch 26. The speed is transmitted to the main shaft 35 of the main shaft 35, and the speed is reduced to an appropriate gear ratio by the transmission 34 and transmitted to the chain sprocket 41, and the rear wheel is driven via a chain (not shown) and the rear wheel chain sprocket, so that the motorcycle can run. Become.

Furthermore, the rotational torque of the rear crank 5b is:
The torque 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 wheels in the same manner as the torque transmission of the front crank 5b.

Further, as the engine 1 operates, air is transmitted through the carburetor 12a, reed valves 11a, 11b, crank chambers 6a, 6b, and scavenging passages 17a, 17b, 18a, 18b of the rear air supply system devices 13a, 13b. , the air-fuel mixture is taken into the cylinders 2a and 2b, respectively, and
The combustion gas in the cylinders 2a, 2b is scavenged, and the exhaust port 14 of the exhaust system device 16a, 16b located at the front is scavenged.
a, 14b and exhaust passages 15a, 15b.

When the cranks 5a and 5b are connected to the primary shaft 20 in the phase relationship shown in FIG. 2, these crankshafts rotate in opposite directions, so that the front and rear cylinders 2
The rotational vibrations in the longitudinal direction at a and 2b cancel each other out, reducing the vibration of the entire engine, improving the performance of the engine, and making the crankcase thinner.As a result, the crankshaft Together with this arrangement, it is possible to further reduce the weight and size of the engine.

Further, in the above embodiment, since the two cylinders 2a and 2b are arranged in a staggered manner in the front, back, left and right as shown in FIG. 3, the front, back, left and right dimensions of the entire engine 1 can be reduced. .

Furthermore, as shown in FIG. 2, the cylinder 2b which is located at the rear of the front and rear cylinders 2a by Z is located above, so that the longitudinal dimension of the engine 1 as a whole 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 disposed below the crank 5b, the transmission 34 is moved forward and connected to the crank 5b. Since they can be placed adjacent to each other, the longitudinal length of the crankcase can be shortened and the overall dimensions of the engine 1 and transmission 34 can be made compact.

Moreover, 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. Since the auxiliary cover 42 is covered, by removing the auxiliary cover 42 and the idle gear 24, the crank angle of the front cylinder 2a and the rear cylinder 2b can be changed as appropriate. 2a,
You can easily change the explosion timing of 2b.

Furthermore, since the crank chamber 6 is vertically divided into three parts by planes 10a and 10b that pass through the center line of both pistons 2a and 2b and are perpendicular to the crankshaft, the crank chamber 6 is vertically divided into three parts.
, the primary shaft 20, the main shaft 35 of the transmission 34, and the countershaft 4
0 on the same plane, the arrangement of these parts can be freely changed to make the entire engine 1 and transmission 34 sufficiently compact.Moreover, the engine 1 can be easily machined and is lightweight. Nevertheless, an engine 1 with high rigidity can be obtained.

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

In the above embodiments, 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.

[0031]

Effects of the Invention The present invention provides at least two
Because a multi-cylinder engine is constructed by arranging the cylinders offset longitudinally and vertically, the longitudinal dimensions of the engine can be shortened, and the structural members related to the front and rear cylinders can be integrated. In addition, since this is a multi-cylinder engine with at least a portion of the transmission located below the rear crankshaft located higher than the front crankshaft, the transmission is adjacent to the front crankshaft and the crankcase itself is It is possible to shorten the longitudinal length of the engine, making it possible to further reduce the weight and size of the engine.

[Brief explanation of drawings]

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

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

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2;

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 2;

6 is a cross-sectional view taken along line VI-VI in FIG. 2. 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, 1
1... 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, 2
4... Idle gear, 25... Flywheel gear, 26... Multi-plate friction clutch, 27... Disc, 28... Plate, 2
9... 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] Claim 1: At least two cylinders are arranged in front and behind, a crankshaft of a rear cylinder is arranged behind a crankshaft of a front cylinder, and a transmission is arranged in a crankcase that houses the front and rear crankshafts. In the 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 with the following features.