JPH0727414Y2 - gasoline engine - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a gasoline engine, and more specifically, it is an improvement of a small gasoline engine preferably used as a drive source for a brush cutter or the like. .

[Prior art and its problems]

2. Description of the Related Art Conventionally, small gasoline engines have been widely used as a drive source for hand-held and back-worn brush cutters.

By the way, in this kind of small gasoline engine, in order to reduce the size and weight of the engine, a rotor having a magnet for power generation is provided at the free end of the crankpin, and a coil for power generation is provided in the crankcase corresponding to the rotor. Some of them were constructed according to Japanese Patent Laid-Open No. 59-37273.

However, since this engine has a rotor attached to the free end of the crankpin, the piston and rotor always move in the same direction, and the swing due to the reciprocating motion of the piston increases, so to reduce the swing. Furthermore, in order to obtain a predetermined inertial force, the weight of the weight must be increased, and therefore it is structurally impossible to reduce the weight of the engine itself even if the cooling fan that also serves as the flywheel is downsized or omitted. Met.

In addition, since it is necessary to secure a space for the rotor to rotate in the axial direction of the crankpin, the crankshaft is slightly shorter than the conventional gasoline engine in which the cooling fan is integrally provided with the magneto ignition mechanism. However, since the crankcase became large, the position of the ignition mechanism was virtually changed, and it was not possible to reduce the size of the crankcase. In addition, it was necessary to manufacture a new crankcase, resulting in higher costs. .

On the other hand, there is an ignition mechanism having a configuration in which a plurality of magnets are fitted to the peripheral surface of a weight made of a non-magnetic material to form magnetic poles, and an ignition coil is provided at a position corresponding to the magnets of the crankcase. No. 58-501188).

Since this ignition mechanism has a plurality of recesses formed on the side surface or the peripheral surface of the weight and magnets are fitted into the recesses, the manufacturing process becomes complicated, and dimensional accuracy that takes into account changes due to thermal expansion is also required. In addition, there is a problem that the cost becomes higher than that of the weight made of iron or iron-based alloy.

[Means for solving problems]

Therefore, in this invention, in order to solve the above-mentioned problems, a weight is formed by sequentially superposing a permanent magnet and a magnetic piece in a direction facing the magnetism member and the crankpin of the magnetism member. By the configuration that sets the permanent magnet so that the magnetic member and the magnetic piece have different polarities,
It is intended to easily reduce the size and weight of an engine with a low cost and a simple manufacturing process.

In this case, it is preferable to form a bulge on the lower outside of the crankcase and accommodate the ignition coil in the bulge because the airtightness of the crankcase can be easily maintained.

[Action]

In the gasoline engine according to the present invention, the weight itself is formed as a magnetic pole by setting the permanent magnet so that the magnetic pole member and the magnetic pole piece have different polarities. The engine is operated by the action of the ignition coil provided.

〔Example〕

Next, a preferred embodiment of a gasoline engine according to the present invention will be described in detail with reference to the accompanying drawings.

1 and 2, the gasoline engine according to the present invention has a weight 14 of a crank 12 in a crankcase 10.
A piston 18 is connected to a rod 16 extending so as to face a and 14b, a starter 22 is provided at one end of a crankshaft 20, and an output shaft 26 is provided at the other end via a centrifugal clutch 24. Connect and further centrifugal clutch 24 and crankcase
A cooling fan 28 made of, for example, a light metal, a synthetic resin or the like is axially mounted between the cooling fan 28 and the shaft 10.

Further, the weight 14a is made up of a magnetically magnetic member 36 made of iron or an iron-based alloy and a crank pin 38 of the magnetically magnetic member 36.
Permanent magnet 40 and iron piece 42 that is a magnetically-charged piece in the direction opposite to
Are sequentially superposed, and the permanent magnet 40 is set so that the iron piece 42 becomes the S pole when the magnetically polarized member 36 is the N pole, and the iron piece 42 becomes the N pole when the magnetically polarized member 36 is the S pole. The magnet type ignition mechanism 30 is constituted by the magnetic pole 32 and the ignition coil 34 (see FIG. 3).

Further, the ignition coil 34 is located inside the crankcase 10 through holes 46, 46 formed in the crankcase 10 at both ends of the U-shaped iron core 44 at a position corresponding to the magnetic pole 32 on the outer side of the lower part of the crankcase 10. It is arranged to be exposed.

In this case, if a suitable sealing material 48 is filled on the peripheral surface of the U-shaped iron core 44 inserted into the holes 46, 46, the crankcase
10 can be made airtight.

Further, the cooling fan 28 has a large number of blades 52 on one side of the disk 50.
Are formed by arranging radially, but as in the present embodiment, the outer peripheral portion of the disk 50 may be formed thick (fourth
Further, it is preferable that the diameter of the cooling fan 28 itself is set to be large to increase the inertial force during rotation so as to smooth the rotation of the engine.

The gasoline engine according to the present invention configured as described above is
The weight 14a (the magnetic pole 32) is rotated by pulling the starter 22 and rotating the crankshaft 20, and the gasoline is ignited by the plug discharge due to the change in the magnetic flux between the magnetic pole 32 and the ignition coil 34 to operate the engine.

Further, FIG. 5 shows that a part of the crankcase 10 is bulged to accommodate the ignition coil 34 in the bulged portion 54, and only the conductive wire is grommet 56 made of rubber or the like through the crankcase. 10 is another embodiment of the gasoline engine according to the present invention that is led out to the outside, in this case, the crankcase
The airtightness of 10 can be performed more easily.

It should be noted that, in the above-mentioned embodiment, the current interruption type ignition mechanism in which the primary coil and the secondary coil are integrated has been described for the sake of convenience.
In the case of a current interruption type ignition mechanism having a separated secondary coil or a capacitor discharge type ignition mechanism having a separated generating coil, the primary coil or the generating coil can be similarly configured by providing it at a position corresponding to a magnetic pole of a crankcase. Of course.

[Effect of device]

As described above, according to the gasoline engine of the present invention, the weight is formed by sequentially superimposing the permanent magnet and the magnetic piece in the direction facing the magnetism member and the crankpin of the magnetism member. Since the weight itself is configured as a magnetic pole, it is possible to avoid complexity in manufacturing such as requiring dimensional accuracy in consideration of thermal expansion and the like, and to manufacture it by simply processing a conventional crank. In addition, since the weight is made of relatively inexpensive iron or iron-based metal, it is possible to easily reduce the size and weight of the engine at low cost.

Further, not only the thickness and weight of the magnet attached to the cooling fan can be reduced, but also the cooling fan can be made of a lightweight and inexpensive synthetic resin, so that the cost and the size can be further reduced. It has various advantages and its practical effect is extremely large.

Although the preferred embodiment of the gasoline engine according to the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit of the present invention. Is.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a preferred embodiment of a gasoline engine according to the present invention, FIG. 2 is a sectional view taken along line II-II of the gasoline engine shown in FIG. 1, and FIG. 3 is gasoline shown in FIG. FIG. 4 is a cross-sectional explanatory view showing the mounting state of the ignition coil of the engine, FIG. 4 is a side view of the cooling fan of the gasoline engine shown in FIG. 2, and FIG. 5 is another embodiment of the crankcase of the gasoline engine shown in FIG. It is sectional explanatory drawing which shows. 10 …… Crankcase, 12 …… Crank, 14 …… Weight, 16 …… Rod, 18 …… Piston, 20 …… Crankshaft, 22 …… Starter, 24 …… Centrifugal clutch, 26 ……
Output shaft, 28 ... Cooling fan, 30 ... Magnet type ignition mechanism, 32 ... Magnetic pole, 34 ... Ignition coil, 36 ... Magnetic member, 38 ... Crank pin, 40 ... Permanent magnet, 42 ... Iron piece, 44 …… U-shaped iron core, 46 …… Hole, 48 …… Sealant,
50 …… disk, 52 …… blade, 54 …… bulge, 56 …… grommet,

Claims (2)

[Scope of utility model registration request] 1. A gasoline engine in which a magneto ignition mechanism is constituted by magnetic poles formed on a weight of a crank and an ignition coil arranged at a position corresponding to the magnetic pole of a crankcase. The permanent magnet is formed by sequentially superposing a permanent magnet and a magnetic piece in a direction facing the crankpin of the magnetic member, and the permanent magnet is set so that the magnetic member and the magnetic piece have different polarities. And a gasoline engine. 2. A gasoline engine according to claim 1, wherein a bulging portion is formed on the lower outside of the crankcase and an ignition coil is housed in the bulging portion.