JPH0140226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive gear device for a distributor.

A distributor is a power distributor that sends the high-voltage current generated in the coil to the spark plugs of each cylinder according to the firing order. It consists of an automatic advance device to obtain the correct ignition timing. Furthermore, with the advancement of electronic engine control, recent distributors have become fully equipped to control ignition timing.
Engines are increasingly equipped with transistor-type igniter pick-ups or built-in crank angle sensors that detect the rotational angle of the engine. As a result, the rotation accuracy of the distributor is required to be higher than before (see Japanese Utility Model Application No. 55-67358).

By the way, the distributor has conventionally been configured to be driven in synchronization with the rotation of the engine, and by meshing the gears on the camshaft and the gears on the distributor shaft, the rotation of the crankshaft is controlled via the camshaft. It is transmitted to the distributor shaft at a predetermined reduction ratio of 1/2 (Nissan Motors
“Service Bulletin No. 119 P.48” published by Co., Ltd. in April 1966
reference). Since the camshaft and the distributor shaft are disposed in a plane perpendicular to each other, both gears are helical gears. Further, since the backlash between both gears causes fluctuations in the ignition advance angle, this backlash is made small due to dimensions and structure.

However, in the drive gear device of such a conventional distributor, both gears are made of metal, and there are limits to machining accuracy and reduction of breakage. It was insufficient. In other words, the backlash caused by machining is large, and the rotation of the distributor shaft fluctuates significantly (±3 degrees in crank angle) relative to the engine rotation, resulting in fluctuations in the ignition advance angle. In addition, since both of the above gears are screw gears (staggered helical gears), the tooth surfaces are prone to point contact and wear (particularly when the backlash is large, the rotational fluctuations cause the tooth surfaces to collide with each other and cause significant wear).
Rotation fluctuation increases. It should be noted that if this breakage is attempted to be reduced by machining, the cost will increase significantly and the yield will also decrease. Furthermore, in view of this point, we proposed a distributor with a brake (see Japanese Patent Application No. 56-184096), but this device would be significantly costly, and if the brake becomes low, the ignition advance angle will increase. This has the problem that the fluctuation of the angle becomes large. Furthermore, gears whose entire body is made of synthetic resin such as nylon resin are mainly used as parts for low-torque, light-load applications, so they can be
It is unsuitable for parts that are subject to high impact loads due to its lack of strength.
There is a problem that errors occur in detecting rotation, etc.

This invention was made by focusing on these conventional problems.The tooth surface of a machined metal gear is coated with powdered nylon resin, and then heated to create a nylon coating with a thickness of 100 to 400 microns. By coating with resin, the aim is to reduce the backlash, reduce the rotational fluctuation of the distributor shaft, suppress the fluctuation of the ignition advance angle, and reduce the cost.

A drive gear device for a distributor according to the present invention includes a distributor shaft, a drive shaft that rotates in synchronization with the rotation of an engine, and a pair of metal gears that are respectively fixed to both shafts and mesh with each other. , a drive gear device for a distributor comprising: a tooth surface of at least one of the metal gears;
Powdered nylon resin is powder coated and then heated.
It is coated with 100-400 micron nylon resin.

The present invention will be explained below based on the drawings.

1 to 5 show an embodiment of this invention. First, the configuration will be explained. In FIGS. 1 and 2, 1 indicates a distributor, and inside this distributor 1, a contact breaker, a rotor, a centrifugal advance device, etc. are incorporated. A distributor shaft 2 to which a rotor, a cam, etc. are fixed is rotatably supported by a housing boss portion of the distributor 1, and a metal gear (helical gear) 3 is fixed to its lower end. A camshaft 4 rotates in synchronization with the crankshaft of the engine, and a metal gear (helical gear) 5 that meshes with the gear 3 is fixed to one end of the camshaft 4. Note that the distributor shaft 2 and the camshaft 4 are arranged in a plane that is orthogonal to each other. Further, the distributor shaft 2 is driven via a camshaft 4 and gears 3 and 5 to a crankshaft at a predetermined reduction ratio (1/2 in the case of a four-stroke engine).

Here, the tooth surface of the gear 3 (the surface that participates in the meshing of the teeth) is coated with nylon resin (for example, 66 nylon) of a predetermined thickness. In FIG. 2, A indicates a coating layer of nylon resin. This coating applies to both gears 3 and 3.
5 may be applied to both tooth surfaces. Further, the thickness of this coating layer A is 100 to 400 microns, but the optimum value is 150 to 200 microns. If the thickness of this coating layer A is too thin (100μ
(Below) The elasticity of nylon resin cannot be utilized and sufficient effects are not produced. Furthermore, if the thickness is less than 50 μm, there will be problems such as variations in thickness and formation of pinholes. On the other hand, if it is too thick (400μ or more), it will be plastically deformed by the load, which will easily cause the rotational vibration, and furthermore, it will be more likely to peel off from the base metal part. FIG. 4 shows the test results for determining the optimum value of this thickness.

The coating of the gear 3 is performed by applying an adhesive to the tooth surface of the gear 3, applying powdered nylon resin by a powder coating method, and then heating.

As mentioned above, since the tooth surface of the metal gear 3 after machining is coated with nylon resin, it is possible to reduce the breakage of the gears 3 and 5, and the elasticity of the nylon resin widens the contact area of the tooth surface. The surface pressure of the contact area decreases. In addition, this coating layer A buffers the tooth surfaces of the gears 3 and 5 from violently colliding with each other due to rotational fluctuations of the camshaft 4, so that wear of the tooth surfaces of the gears 3 and 5 can be prevented. As a result, the distributor shaft 2
It is possible to reduce the amplitude of the rotational fluctuation (with a crank angle of 1°), and it is also possible to perform stable operation over a long period of time. , therefore,
The accuracy of engine rotation speed detection by the crank angle sensor built into the distributor 1 is improved, which in turn leads to purification of exhaust gas and improved fuel efficiency.

Further, FIG. 3 shows changes in the amplitude of the ignition advance angle for gears made of various materials in a durability test of the gear device under actual engine operation. The engine used is a 6-cylinder, 2000c.c. engine, and the durability conditions are full load and 6000rpm. In the figure, the vertical axis is no load,
The amplitude of the ignition advance angle (degrees) at 800 rpm is shown, and the horizontal axis shows the durability time (Hrs).The conventional metal gear (without coating) is represented by the polygonal line x, the nylon resin coating gear 3 is represented by the polygonal line y, and the tin Metal gears are indicated by a polygonal line z, and Teflon coated gears are indicated by a polygonal line w. As a result, it can be seen that the gear 3 coated with nylon resin is the most excellent in preventing fluctuations in the ignition advance angle and in durability. Note that the Teflon coated gear is easily peeled off and has poor durability, as shown by w.

Furthermore, Figure 4 shows the test results of the ignition advance angle fluctuation (vertical axis) and coating thickness (horizontal axis) after the durability test when the thickness of coating layer A of gear 3 was varied. . Durability conditions are full load,
Continuous operation at 6000 rpm for 200 hours, and test results were evaluated at no load and 800 rpm operation. As a result, as mentioned above, the thickness of coating layer A is
It can be seen that 100 to 400μ is preferable. The reason why the optimum value of this thickness is set to 150 to 200μ is that the lower limit is technically restricted (for example, making the surface of coating layer A smooth), and the upper limit is restricted by the standard value of gears, etc. (For example, if a conventional gear is coated, the tooth thickness of the gear itself must be reduced, resulting in a decrease in strength.)

Moreover, FIGS. 5a, b, and c show the effects of this invention. Figure 5a shows the relationship between the engine speed and the ignition advance amplitude under no-load operating conditions, and Figure 5b shows the relationship between the engine speed and the ignition advance amplitude under no-load operating conditions.
When the pressure inside the intake pipe is −
The values at 300mmHg are shown respectively.
In the figure, x indicates no coating (conventional example);
y represents the case where coating is applied (this invention).

As explained above, according to this invention,
As a result of being able to reduce the backlash between the gears, it is possible to suppress (stabilize) rotational fluctuations of the distributor shaft, and it is possible to prevent fluctuations in the ignition advance angle. In addition, the contact area of the tooth surface of the gear is widened and shock can be buffered, improving wear resistance and reducing operating noise. Furthermore, if the coating thickness is appropriately controlled according to the dimensions of the gear, its dimensional accuracy can be further improved. Also,
This coating is significantly cheaper than machining the gear.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing one embodiment of a drive gear device for a distributor according to the present invention, and FIG.
The figure is a schematic sectional view of the gear meshing portion of the device, and FIGS. 3 to 5 are graphs showing the effects of the device. DESCRIPTION OF SYMBOLS 1... Distributor, 2... Distributor shaft, 3, 5... Gear, 4... Camshaft (drive shaft), A... Nylon resin coating layer.

Claims (1)

[Claims] 1. A drive gear device for a distributor comprising a distributor shaft, a drive shaft that rotates in synchronization with the rotation of the engine, and a pair of metal gears that are respectively fixed to both shafts and mesh with each other, Powdered nylon resin is powder coated on the tooth surface of at least one of the metal gears, and then heated to 100%
A drive gear device for a distributor characterized by being coated with ~400 micron nylon resin.