JPH0814256B2 - Anti-vibration structure of internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration structure that absorbs vibration, noise, etc. generated in an internal combustion engine inside the internal combustion engine.

(Prior Art) In order to absorb vibration generated in an internal combustion engine, it is conventionally known to interpose a vibration isolating member at a joint portion of a plurality of members forming the internal combustion engine to reduce the impact. For example, in JP-A-55-175620, an elastic ring is interposed between the crankcase and crank bearing, and in JP-A-53-3310, a vibration-proof metal is interposed between the engine block and the cylinder liner. ing.

(Problems to be Solved by the Invention) In each of the above-mentioned conventional techniques, vibration or impact applied to individual parts such as a crank bearing or a cylinder liner can be mitigated,
It is not possible to absorb the vibration of the entire internal combustion engine. For example, when the air-fuel mixture explodes, the shock due to the explosion pressure is transmitted to the crankcase via the piston and the cylinder, but in the case of the above-mentioned KAISHO Sho 55-175620, the shock transmitted from the cylinder side cannot be mitigated. Kaisho 53-310 cannot absorb the vertical impact on the cylinder and the impact from the piston.

In addition, since the anti-vibration member in these technologies is mounted inside the engine, it must be a material with high oil resistance or heat resistance, but under those conditions, select a material that obtains the required elasticity. Is limited, and in addition, because it is located inside, inspection and repair are difficult.

(Means for Solving the Problems) The present invention solves the above problems by a simple structure. The means is a crank for an internal combustion engine in which a cylinder is connected to a crankcase and a crank bearing is attached. Crank bearings are mounted on bearing holders installed at intervals inside the case to support the crankshaft, and the bearing holders are connected to cylinder blocks with bolts to form bearings.
A cylinder coupling is formed, the crankshaft is projected from the shaft sealing hole of the crankcase, and the bearing-cylinder coupling and a mounting portion such as the crankcase are arranged in the same direction outside the coupling portion of the bearing holder. It is characterized in that they are connected by individual bolts, and the mounting portion by the bolts has an elastic body which is coaxial with the bearing-cylinder combination and the bolts.

(Operation) With the above means, the vibration transmitted from the piston through the crankshaft and the shock and vibration transmitted through the cylinder are both absorbed by one elastic body, and only the damped vibration is present in the crankcase. It is transmitted.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a two-cycle internal combustion engine, 2 is its crankcase, and is formed from two left and right case shells 2L and 2R. An oil seal 2a is attached to a crankshaft penetrating portion to form a shaft sealing hole 2b. A cylinder mounting portion 2c is provided at a position apart from the shaft sealing hole 2b, and a screw hole 2d is formed therein.

The crankshaft 3 having the crankpin 3a is supported by a crank bearing 4, which is held by a bearing holder 5 provided inside the crankcase 2. The bearing holder 5 also comprises two holder members 5L and 5R on the left and right,
Both members are provided with a bearing holding portion 5a and a coupling portion 5b, and a screw hole 5c is formed in the coupling portion 5b.

The cylinder 6 includes a cylinder block 6a and a cylinder head.
The cylinder block 6a includes a bore 6c and a mounting flange 6d, and the mounting flange 6d is provided with a coupling hole 6e and a mounting hole 6f.

The bearing holder 5 and the cylinder 6 are integrally connected by a plurality of fixing bolts 7, and the left and right holder members 5L and 5R are also appropriately connected to each other to form a bearing-cylinder combined body 8 and a wall of the combined body 8. A series of scavenging passages 9, 9 are formed in the section. A piston 10 is inserted into the bore 6c and is connected to the crank pin 3a by a rod 11.

An elastic body 12 made of rubber and having flanges provided at both ends of the tubular portion is fitted into the mounting hole 6f of the cylinder 6. And
A bolt that passes through the elastic body 12 by fitting the shaft sealing holes 2b, 2b of the case shells 2L, 2R of the crankcase 2 into the crankshaft 3 and connecting the case shells 2L, 2R by an unillustrated means to form an integral crankcase. By screwing 13 into the screw hole 2d, the bearing-cylinder coupling body 8 is connected to the crankcase 2 in a floating state via the elastic body 12. At this time, a minute gap c is formed between the two portions 2 and 8.

With the above configuration, among the impacts generated by the operation of the internal combustion engine, the impact transmitted from the piston 10 is transmitted to the mounting flange 6d of the cylinder 6 via the rod 11, the crankshaft 3, the bearing 4, and the bearing holder 5, while being transmitted to the cylinder. Since the impacts that are applied are transmitted to the mounting flange 6d as they are, the impacts and the vibrations due to the impacts are all absorbed or absorbed by the elastic body 12 of one type.

In this internal combustion engine 1, as shown in FIG.
The inner and outer sleeves 14a, 14b and the intermediate rubber sleeve 14 are provided between the large end 11a of the needle and the needle roller 3b of the crank pin 3a.
By providing the cushioning sleeve 14 made of c, the cushioning action can be further improved.

In this internal combustion engine 1, since the crankshaft 3 is in a floating state, the crankshaft center position fluctuates slightly due to vibration. Therefore, a belt transmission or a flexible joint which is tolerant to shaft position fluctuation is used. It is preferable that the electric power is transmitted to the load as a prime mover of a vehicle having a V-belt transmission as shown in FIG.

In the figure, a driving pulley 20a of a V-belt transmission 20 is attached to a crankshaft 3, and a V-belt 20b and a driven pulley 20 are attached.
It is connected to the gear type speed reducer 21 by c. The action radius of each pulley is automatically adjusted by the centrifugal device 20d and the spring 20e.

The gear reduction device 21 includes a drive shaft 22, a counter shaft 23, and an output shaft.
24 is provided, and the drive wheels 25 are rotated by being decelerated by gears 22a, 23a, 24a and the like provided on each shaft. A one-way clutch 23c may be provided in the gear train to prevent reverse driving from the wheel side.

By connecting the V-belt transmission 20 to the crank shaft 9 in this manner, the vibration absorption transmitted to the crank shaft 9 is further alleviated by the vibration absorption of the transmission 20 and smooth rotation is achieved on the wheel 25. Transmitted. Further, when it is desired to attach a driving gear to the crankshaft 3 without using a belt transmission and to make an irregularity due to the gear train, either attach the driving gear to the crankshaft 3 via a buffer or reduce the inter-shaft distance slightly. By engaging the driving gear with the driven gear, the clearance between the teeth is reduced, and the generation of noise can be suppressed.

The case where the present invention is applied to the 2-cycle engine has been described above, but the same method can be applied to the 4-cycle engine.

(Effects of the Invention) According to the present invention, as described above, since the bearing-cylinder combination is formed and attached to the crankcase via the elastic body, not only the vibration transmitted from the piston side but also the vibration transmitted from the cylinder side. Can be alleviated at the same time, and an internal combustion engine with low vibration can be obtained.

Moreover, since the elastic body is installed outside the internal combustion engine, deterioration of the material due to heat and lubricating oil is small, and the elastic body is durable and can be easily inspected and repaired.

Further, since vibrations transmitted through a plurality of paths are buffered by the elastic body provided in the mounting portion by the bolt, the amount of the elastic body used is small and the configuration is simple.

Further, the coupling between the bearing holder and the cylinder block and the coupling between the crankcase and the bearing-cylinder coupling body are performed by bolting, so that the coupling structure is simple.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view of a shock absorber that can be used on the large end side of a rod, and FIG. 3 is a transmission device of a vehicle using an internal combustion engine embodying the present invention. FIG. 2 ... Crank case 3 ... Crank shaft 4 ... Bearing 5 ... Bearing holder 6 ... Cylinder 8 ... Bearing-cylinder combination 12 ... Elastic body

Claims (1)

[Claims] 1. In an internal combustion engine in which a cylinder is connected to a crankcase and a crank bearing is attached, a crank bearing is attached to a bearing holder installed at a space inside the crankcase to support a crankshaft. The holder is connected to the cylinder block with a bolt to form a bearing-cylinder combination, the crankshaft is projected from the shaft sealing hole of the crankcase, and the mounting portion of the bearing-cylinder combination and the crankcase is a bearing holder. Is connected by a plurality of bolts arranged in the same direction on the outer side of the joint portion of the above, and the mounting portion by the bolt is such that an elastic body coaxial with the bolt is interposed between the bearing-cylinder joint body and the bolt. A characteristic is a vibration-proof structure for an internal combustion engine.