JPH059500Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention involves attaching a rotor with a magnet to the crankshaft via a key, and attaching an ignition coil to the fixed side of the rotor that corresponds to the magnet. Regarding the magnetic ignition device installed.

[Prior art] For example, in a small general-purpose engine, the third
As shown in the figure, a key 2 is formed at the end of the crankshaft 1, a rotor 4 is attached via a keyway 3 that fits into the key 2, and a rotor 4 is attached to the outer periphery of the rotor 4 in the direction of N→S→N. While the magnets 5 are arranged in this order, an iron core 6 and an ignition coil 7 are arranged on the engine body side facing the outer periphery of the magnets 5 (see Utility Model Application No. 159628/1983).

Here, FIG. 5 shows an ignition circuit diagram of such a magnetic ignition device, in which: (1) Voltage is generated at L ₁ due to the rotation of the rotor 4 (FIG. 3), and first, the base current of Tr ₁ is IB ₁ flows. And the current IC ₁ amplified by Tr ₁
flows to form a primary circuit.

(2) Furthermore, the rotor 4 (Fig. 3) rotates, and L ₁
When the voltage generated in Tr 2 increases and reaches the ignition timing position, the generated voltage overcomes the resistance r ₂ and the base current IB ₂ of Tr ₂ starts flowing again. At that moment when IB ₂ begins to flow, Tr ₂ becomes conductive and collector current Ic ₂ flows.

(3) On the other hand, since the internal resistance of Tr ₂ is much lower than that of Tr ₁ , all IB ₁ that had previously flowed through Tr ₁ becomes Ic ₂ and changes its flow to go via Tr ₂ . .

(4) In this way, since the base current IB ₁ of Tr ₁ momentarily stops flowing, the large current Ic ₁ that had been flowing through L ₁ until then is also abruptly cut off.

(5) Due to sudden current changes in the primary circuit, the secondary side L ₂
High voltage is generated and sparks fly from the spark plug SP.

This flying spark occurs at an angle θR before the key 2 and key groove 3 in FIG. 3 are on the Y line.

In such engines, the clockwise direction shown in Figure 3 is generally the forward rotation direction.
In other words, on the output side, which is the other end of the crankshaft 1, the direction in which the crankshaft 1 is rotated in the opposite counterclockwise direction when viewed from the axis side is defined as the forward rotation direction.

Here, for example, if the engine is a small general-purpose type, it is often installed in brush cutters, backpack-powered sprayers, etc., but in addition to the engine with the forward rotation specification mentioned above, these engines also have a reverse rotation specification. In other words, an engine with a specification in which the crankshaft 1 rotates in a clockwise direction when viewed from the output side is also required, and in order to cope with this problem, the following measures have been taken in the past.

In other words, as a countermeasure, the rotor 4 has a different position of the keyway 3 as shown in Fig. 4, and the magnet 5 is magnetized from N to S when it rotates normally, but from S to N. Type to be considered (former)
and the latter type in which the rotor 4 has the keyway 3 in a different position and the ignition coil 7 is installed with the winding direction reversed.

[Problem to be solved by the invention] Here, in the former type, if the rotor 4 for forward rotation shown in FIG. If the direction is not reversed as shown in FIG. 4, when the rotor 4 in FIG. 3 is used for reverse rotation, _the current Ic ₁ in the primary coil L ₁ in FIG. , since the base current IB ₁ flows only in the direction of the current flowing during forward rotation, as a result, the current
This is due to the fact that IB ₁ and IB ₂ do not flow and no sparks occur in the spark plug SP. For this reason, according to the former type, in addition to the rotor 4 shown in Fig. 3, the reverse rotation The rotor 4 is required.

On the other hand, also in the latter type, two types of rotors 4 are required for the same reason as in the former type.

For this reason, not only the rotor 4 but also two types of ignition coils 7 are required for each of forward and reverse rotation, which is disadvantageous in terms of manufacturing and parts management.

Note that Japanese Utility Model Application Publication No. 60-3284 discloses a method of providing a plurality of ignition coil mounting bosses on the crankcase so that the ignition coil can be placed at any position on the outer circumference of the rotor. ing.

With this method, by selecting the installation position of the ignition coil, one type of rotor can support forward and reverse rotation of the engine, but for the reasons mentioned above, two types of ignition coils are required, and even with this method, We have the same issues.

This invention was made in view of the above problems, and aims to eliminate disadvantages in terms of manufacturing and parts management regarding the rotor and ignition coil.

[Means for Solving the Problems] In order to achieve the above object, in this invention, the rotor has two keyways for forward rotation and reverse rotation, and the ignition coil has a first position for forward rotation. And the second one for reversal, which is rotated 180 degrees from this.
It is said that it can be selectively placed in the following postures.

[Function] With this invention having the above configuration, it is sufficient to use only one type of rotor and ignition coil regardless of whether it is for forward rotation or reverse rotation.

[Example] An example of this invention will be described below with reference to the drawings.

Figures 1 and 2 show the main parts of the ignition system for a small general-purpose engine installed in various working machines such as brush cutters and backpack-powered sprayers.
The figure shows a normal rotation specification that rotates clockwise when viewed from the starter side and counterclockwise when viewed from the output side, and Figure 2 shows a reverse rotation specification that rotates counterclockwise when viewed from the starter side. The following are examples of each.

In FIG. 1, reference numeral 1 denotes a crankshaft, and a key 2 is integrally protruded from one location on the outer periphery of the crankshaft 1.

4 is a rotor, and magnets 5 are arranged on its outer periphery in the order of N→S→N.
The keyways 3R and 3L provided on the inner circumference of the
They are arranged at angles of θL (approximately 25 degrees) in the clockwise direction, and in this case, one of them is the forward rotation keyway 3R, and the other is the reverse rotation keyway 3L.

In consideration of assembly, an R stamp (or protrusion) is formed near the forward rotation keyway 3R, and an L stamp (or protrusion) is formed near the reverse rotation keyway 3L. ing.

On the other hand, 6 is the iron core, and the engine body (not shown)
It is attached symmetrically to the sides via attachment points 8, 8.

7 is an ignition coil, with both iron cores 6,
The ignition coil 7 can be installed with the iron core 6 facing up (first position) or facing down (second position) rotated by 180 degrees. I can do it.

In this case, by arranging core attachment holes (not shown) corresponding to the attachment points 8, 8 symmetrically with respect to the line Y, the attachment direction can be selected from the front to the back.

In addition, SP stands for a spark plug, SW stands for a stop switch, and 9 stands for an igniter.

In the above configuration, the rotor 4 has two keyways 3R and 3L for forward rotation and reverse rotation, and the ignition coil 7 can be installed facing up or down. In this example, if the keyway 3R for forward rotation is fitted to the key 2, it is possible to provide an ignition device with the same forward rotation specifications as shown in FIG. 3, but as shown in FIG.
Fit the key 2 into the keyway 3L for reverse rotation and rotate the rotor 4.
In addition, by installing the ignition coil 7 in the opposite order by rotating the magnet 5 by 180 degrees from that shown in FIG. 1, and by reversing the direction of the coil winding, It is possible to provide an ignition device with reverse specifications similar to the above.

For this reason, only one type of rotor 4 and ignition coil 7 is required, which is very advantageous in terms of manufacturing, parts management, etc.

Note that this invention can also be applied to an ignition device that uses a contact breaker (not shown) to cut off the primary current instead of the above-mentioned transistor. However, in this case, the point cam is installed as a separate piece that is fitted into the crankshaft, and in the case of forward rotation specifications, it is fitted from the opposite direction.

[Effects of the invention] As explained above, according to this invention, it is sufficient to prepare only one type of rotor and ignition coil, regardless of whether it is for forward rotation or reverse rotation. Disadvantages in terms of surface and parts management can be eliminated.

[Brief explanation of the drawing]

Figure 1 is a front view of an ignition system showing one embodiment of this invention, Figure 2 is a front view of the ignition system with reverse rotation specification, and Figure 3 is a front view of a conventional ignition system with forward rotation specification. FIG. 4 is a front view of the ignition device shown as a reverse specification, and FIG. 5 is a diagram of a general magnetic type ignition circuit. 1...Crankshaft, 2...Key, 3,3
R, 3L...Keyway, 4...Rotor, 5...Magnet, 6...Iron core, 7...Ignition coil.

Claims (1)

[Scope of utility model registration request] In a magnetic ignition system, a rotor having a magnet is attached to the crankshaft via a key, and an ignition coil is arranged on the fixed side of the rotor corresponding to the magnet. In addition to having two keyways, the ignition coil is capable of being selectively arranged in a first position for forward rotation and a second position for reverse rotation rotated 180 degrees from this position. Magnetic ignition device.