JPH0312050Y2 - - Google Patents

Description

[Detailed explanation of the invention] (Field of industrial application) This invention relates to a generator for a bicycle headlamp, and is designed to prevent excessive voltage from being applied to the light bulb even when the speed of the bicycle changes. This invention relates to a bicycle generator that maintains the voltage at a constant value.

(Prior art and its problems) Generally, a bicycle generator rotates a main shaft that is integrated with the bicycle tire by a drive roller that rotates in contact with the tire, and the rotation of this main shaft causes a permanent magnet on the main shaft to rotate. It rotates to generate electricity, and usually an alternating current generator is used.

However, the output voltage of such a generator increases almost in proportion to the running speed of the bicycle. Therefore, when the bicycle is running slowly, the power generated by the generator is low, and conversely, when the bicycle is running slowly, the generated power is low. If this happens, the voltage generated by the generator will increase. Therefore, if the brightness of the headlamp is set appropriately when the bicycle is traveling at low speeds, the voltage generated by the generator will increase when the bicycle is traveling at high speeds, and excessive voltage will be applied to the headlamp bulb. Conversely, if the headlights are set to an appropriate level of brightness when driving at high speeds, when driving at low speeds the power generated by the generator will decrease, the illuminance of the headlamps will decrease, and they will no longer be able to fulfill their role as headlamps. There is an inconvenience.

In order to eliminate this inconvenience, the lamp illuminance can be maintained at an appropriate level even when the bicycle is running at low speeds, and as the bicycle speed increases, it has a saturation characteristic. If the voltage generated by the machine increases, a method may be adopted to control the power applied to the light bulb. This method involves using a constant voltage device that maintains the output voltage at a constant value in order to prevent the effective power from exceeding the specified power from being applied to the bulb, and the other using a relay or semiconductor to Two methods have been adopted: one is to regulate the average power by varying the time at which electricity is supplied, that is, one is to time-divide power to the light bulbs, and the other is to control the supply of power so that it does not exceed the specified power. However, all of these methods have problems such as at low speeds, the loss is large and sufficient illuminance cannot be obtained, and even at medium speeds, switching is inappropriate and it is not possible to obtain adequate illuminance. , there are problems such as a large number of parts, making it complicated and expensive, and having low reliability.

(Technical means to solve the problem) The present invention is to set the necessary illuminance when the bicycle is traveling at low speed, and to adjust the voltage generated by the generator to the specified voltage of the light bulb when the bicycle is traveling at high speed. The aim is to solve the above-mentioned conventional problems by controlling the voltage generated by the generator, and the technical means for this purpose is to control the voltage of the DC generator when the brush position is at the neutral point. This system takes advantage of the fact that the generated voltage increases and the generated power decreases as the brush position moves away from the neutral point, and is integrated with the drive roller that is driven by contacting the bicycle tire. The present invention is characterized in that it includes a control mechanism that controls the brush position to move away from the neutral point as the rotational speed of the rotating main shaft increases.

(Function) When the spindle rotation speed is a certain low speed, the brush position is located at the neutral point, and as the spindle rotation speed increases, the brush position is controlled to move away from the neutral point. Even if the spindle rotational speed increases, the generated power does not increase accordingly and is maintained at a constant value.

(Example) Next, an example of the present invention will be described based on the drawings.

Figure 1 shows a DC generator for bicycles.
In this figure, 1 is a main shaft rotatably supported in a casing 2 by bearings 3, and a drive roller 4 is fixed to its upper end, and this drive roller 4 rotates in contact with a bicycle tire (not shown). This rotation drives the main shaft 1 to rotate. 5 is an armature provided on the main shaft 1, 6A and 6B are stators, 7 is a commutator, 8A and 8B are brushes,
The armature 5, stators 6A, 6B, commutator 7, and brushes 8A, 8B constitute a power generation section. 9 is a brush position control mechanism that controls the positions of brushes 8A and 8B.

The stators 6A and 6B are made of permanent magnets, with one stator 6A being the N pole and the other stator 6B being the N pole.
The magnetic field is supplied to the armature 5 by making it the south pole. Therefore, the main shaft 1 is
When the armature 5 rotates, a voltage is induced in the winding inside the armature 5 due to electromagnetic induction. Further, the terminals of the windings of the armature 5 are connected to a commutator 7 which is insulated from each other, and the rotating armature 5 is connected to a commutator 7 which is insulated from each other.
The electricity generated is taken out to the outside.

Note that the electromotive force induced in the winding of the armature 5 is proportional to the magnetic flux density and the number of turns of the winding. brush 8
If the positions of A and 8B are at the neutral point, the generated voltage will be the highest, but as the brushes 8A and 8B are rotated and moved away from the neutral point, the generated voltage will become lower. This relationship is shown in FIG. In this figure, the rotation angle θ of the brushes 8A, 8B is plotted on the horizontal axis, and the induced electromotive force V of the armature 5 is plotted on the vertical axis.
It shows how it changes in relation to the rotation angle of 8B.

As shown in FIG. 1, the brush position control mechanism 9 includes a magnet plate 10 fixed to the main shaft 1 concentrically therewith, and a magnet plate 10 fixed to the main shaft 1 concentrically with the magnet plate 10 so as to surround the magnet plate 10. An aluminum cup-shaped conductor 11 is disposed in the aluminum cup-shaped conductor 11 and has a small-diameter cylindrical portion 11a at the lower end rotatably supported by the main shaft 1 via a bearing 12.
Insulating brush holders 13A and 13B are attached to the upper end of the cup-shaped conductor 11 and hold the brushes 8A and 8B, and the conductor 11 is attached to the outer peripheral surface of the cup-shaped conductor 11. Magnet plate 1
0 and a ring-shaped magnetic conductive plate 14 mounted so as to face the brush mount 12, and a small-diameter cylindrical portion 11 of the brush mount 12.
The spiral spring 16 is disposed so as to surround a, and has an inner end fixed to the small diameter cylindrical portion 11a, and an outer end fixedly attached to the casing 1 via a mounting piece 15. The magnet plate 10 is made of a plate-shaped permanent magnet. The magnetically conductive plate 14 is provided to strengthen the magnetic field of the magnet plate 10 relative to the conductor 11, and is made of a ferromagnetic and electrically conductive material such as iron or an alloy of nickel and iron. .

Next, to explain the operation of the brush position control mechanism 9 mentioned above, when the main shaft 1 rotates, the magnet plate 1
0 also rotates, and the magnetic flux of the conductor 11 changes, thereby generating an induced electromotive force in the conductor 11. , eddy currents are generated.
Torque is generated by the interaction between the eddy current and the magnetic field generated by the magnet plate 10. This torque acts on the conductor 11 against the spiral spring 15.
1 and a brush holder 1 integrated therewith.
3A and 13B will be rotated. As the rotation speed of the main shaft 3 increases, the above eddy current also increases,
Since the generated torque also increases, the rotation angle of the brush holders 13A, 13B also increases. Therefore,
As the rotation speed of the main shaft 3, that is, the running speed of the bicycle increases, the rotation angle of the brushes 8A, 8A increases, and as shown in FIG. 2, the induced electromotive force of the armature 5 decreases, but the rotation speed increases. As a result, the induced electromotive force can be maintained at a constant value. This relationship is shown in FIG. In FIG. 3, the horizontal axis represents the rotational speed rpm of the main shaft 1, and the vertical axis represents the induced electromotive force V of the armature 5 or the brush holder 13A,
The rotation angle θ of 13B is taken, and in this figure, 17 is the rotation rpm of the main shaft 1 and the brush holder 13.
The line showing the relationship between A and 13B and the rotation angle θ, and 1
8 is the rotational speed rpm of the main shaft 1 and the armature 5 when the rotation angle θ of the brush holders 13A and 13B is constant.
19 is a line showing the relationship between the induced electromotive force V and the line 19 when the brush holders 13A and 13B are rotationally moved according to the rotational speed rpm of the main shaft 1 according to the present invention, that is, when the brushes 8A and 8B are rotationally moved. This line shows the state of the induced electromotive force in the winding of the armature 5, that is, the voltage generated by the generator.

As is clear from the above explanation, the voltage generated by the generator can be maintained constant from low to high speeds, so the voltage supplied to the headlamp remains constant from low to high speeds, preventing the light bulb from breaking. It is possible to eliminate such problems.

In the above-mentioned embodiment, a generator with a pair of N-S poles was described to simplify the explanation, but the present invention is naturally applicable to a generator with a large number of poles.

(Effects of the invention) According to the invention, it is possible to generate a specified voltage from low speed driving to high speed driving, so it is possible to prevent the bulb from breaking and extend the life of the lamp. A predetermined brightness can be guaranteed.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view showing one embodiment of the bicycle generator of the present invention, Figure 2 is a diagram showing the relationship between the brush rotation angle and voltage, and Figure 3 is the rotation speed of the main shaft and voltage or brush rotation. It is a figure which shows the relationship with a corner. 1... Main shaft, 2... Casing, 4... Drive roller, 5... Armature, 6A, 6B... Stator, 7
...Commutator, 8A, 8B... Brush, 9... Brush position control mechanism, 10... Magnet plate, 11... Conductor, 13A, 13B... Brush holder, 14...
...Magnetic conductive plate, 16...Spiral spring.

Claims (1)

[Claims for Utility Model Registration] 1. A generator with brushes, in which the position of the brushes moves away from the neutral point as the rotational speed of the main shaft, which rotates together with a drive roller that comes into contact with a bicycle tire, increases. A bicycle generator characterized in that it is equipped with a brush position control mechanism that controls the brush position. 2. The brush position control mechanism includes a magnetic plate fixed to the main shaft, and a cup-shaped conductor that is arranged to face the magnetic plate and is supported so as to be rotatable around the main shaft and free of rotation relative to the main shaft. an insulating brush holder attached to the conductor to hold the brush; and an insulating brush holder arranged to surround the main shaft, with an inner end fixed to the conductor and an outer end attached to the generator. A bicycle generator according to claim 1, comprising: a spiral spring fixed to the casing side of the bicycle generator.