JPH04111949U - gear system - Google Patents

Abstract

(57) [Summary] [Purpose] In a 4-stroke engine, resin-based materials are used for gears to reduce noise caused by gear tapping, and the resin material can be freely selected depending on cost, heat resistance, etc. Do it like this. [Structure] The crank gear 10 and the governor gear 30 are made of iron-based material and resin-based material, respectively. A second cam gear 22 made of a resin material is engaged with the crank gear 10 made of an iron material. A first cam gear 20 made of an iron-based material meshes with a governor gear 30 made of a resin-based material. The second cam gear 22 is concentrically adjacent to the first cam gear 20 and joined with a rivet 24.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to gear devices used in cam gears of 4-cycle engines, etc. It is.

0002

[Conventional technology]

Conventionally, as shown in Fig. 4, the crank gear 10 and cam gear 20 have been made of iron-based materials. On the other hand, a gear device in which the governor gear 30 that meshes with the cam gear 20 is made of resin material. There is. The reason why the governor gear 30 is made of resin is that the governor gear 30 is generally complicated. shape, and the flyweight support pin (as shown) that attaches to the governor gear 30. This is to simplify the structure by fitting the parts (not shown) using the elasticity of the resin.

0003 However, the crankcase (not shown) that supports each gear 10, 20, and 30 is For example, if it is made of cast aluminum, aluminum has a higher coefficient of linear expansion than iron. Since the distance D1 between crank gear 10 and cam gear 20 is large, the change in the distance D1 between the shafts of crank gear 10 and cam gear 20 is The amount of expansion and contraction is greater than 10 and 20. Therefore, backlash increases with temperature changes. It fluctuates. Therefore, noise due to gear meshing increases.

0004 Therefore, conventionally, as shown in FIG. 5, the crank gear 10 is made of iron-based material. It is known that the cam gear 20 and governor gear 30 are made of resin material (actually (Refer to Publication No. 1-67371). In this conventional technology, the cam gear 20 is made of resin material. By doing so, the knocking noise generated between the crank gear 10 and the cam gear 20 is reduced. This reduces noise.

[0005]

[Problem that the idea aims to solve]

However, in the above conventional technology, the cam gear 20 and governor gear 30 that mesh with each other are , each are made of resin-based materials, so the crankcases are heated to high temperatures. press with a large force in the space. Therefore, for example, if both have the same hardness, In this case, the tooth surface tends to wear quickly due to surface molecular bonds. Something like this Since the resin material of cam gear 20 and governor gear 30 is made of different materials, expensive It is not possible to freely select the combination of materials, such as the need to use resin, and as a result, the cost This makes it difficult to select materials that take into account stress and heat resistance.

[0006] As a solution to this problem, as shown in Fig. 6, the crank gear 10 and governor gear 30 are The cam gear 20 is made of a resin material, and the cam gear 20 is made of an iron material, so that the resin gears do not mesh with each other. It is also possible to do something like this. However, for example, a small 4 sensor with a shaft output of 5 ps or less In the cycle engine, the crank gear 10 attached to the crankshaft 11 has a small diameter. Therefore, it is not possible to obtain a sufficient wall thickness t in the radial direction, and therefore the crank gear 10 is If it is made of fat, it is difficult to provide enough rigidity to transmit power. .

[0007] This idea was devised in view of the above issues, and can reduce noise as well as The purpose is to provide a gear device in which the material of the fat can be freely selected as required. .

[0008]

[Means to solve the problem]

In order to achieve the above purpose, this invention has a first gear made of iron-based material and a resin-based gear. A second gear made of the same material was concentrically and adjacently coupled.

[0009]

[Effect]

According to this idea, a resin gear is meshed with a first gear made of iron-based material, and By meshing the iron gear with the second gear made of a resin material, each gear is made of resin. Since the steel material and the iron material are in pressure contact, the tapping noise is reduced and the resins are pressed against each other. Since they are not in contact with each other, there are no restrictions on the combinations of resin materials that can be used.

0010

【Example】

Embodiments of this invention will be described below with reference to the drawings. Figure 1 shows the first embodiment, for example, a small 4-stroke engine with a shaft output of 5 ps or less. FIG. In this figure, the engine crankshaft 11, The cam shaft 21 and the cabana shaft 31 are arranged parallel to each other and are made of aluminum casting. The crank case 40 and the crank case cover 41 are pivotally supported.

[0011] A crank gear 10 made of iron-based material is fixed to the crankshaft 11. A first cam gear (first gear) 20 made of iron-based material is integrally formed with the camshaft 21. has been done. This first cam gear 20 includes a second cam gear (second cam gear) made of a resin material. gears) 22 are joined concentrically and adjacently by a holding plate 23 and a rivet 24. It is. A governor gear 30 made of a resin material is rotatably attached to the cabana shaft 31. is installed on. The crank gear 10 is engaged with the second cam gear 22, A governor gear 30 is engaged with the first cam gear 20. Both cam gears 20 and 22 are This constitutes the gear device of this invention, and the shapes of the teeth are set to be the same.

0012 A support pin 32 is fitted into the governor gear 30 by the elasticity of resin. Up A flyweight 33 is swingably attached to the support pin 32, and the number of rotations varies. As the amount increases, the flyweight 33 rotates and adjusts the throttle opening. The engine speed is maintained at a predetermined value.

[0013] In the above configuration, the iron crank gear 10 has a second cam gear made of a resin material. The first cam gear 20 is made of iron-based material and the first cam gear 20 is made of resin-based material. Governor gear 30 is meshing, so check if gears made of ferrous materials are meshing with each other. Therefore, even if the distances between the axes D1 and D2 change and the backlash changes, the striking sound will be significantly different. I can't hear it. Therefore, the noise is lower than when gears are made of ferrous materials. Ru. On the other hand, unlike the conventional example shown in FIG. 5, the resin gears do not mesh with each other. the Therefore, the material of the resin can be freely selected in consideration of cost and heat resistance. By the way, both cam gears 20 and 22 in FIG. 1 have a larger diameter than the crank gear 10. Therefore, since the thickness of the second cam gear 22 in the radial direction can be increased, the thickness of the second cam gear 22 can be increased. Even if the cam gear 22 is made of resin, it has sufficient rigidity to transmit power.

[0014] FIG. 2 shows a second embodiment. In this embodiment, the second cam gear is made of resin material. 22 is integrally molded with the first cam gear 20 by insert molding. Figure 3 shows the Three examples will be shown. In this embodiment, the second cam gear 22 made of resin material is connected to the first gear. It is engaged with the mug gear 20 by serrations or splines 25. In addition, Figure 2 3, the other configurations are the same as those of the first embodiment, and the same parts are Alternatively, corresponding parts will be denoted by the same reference numerals, and detailed illustrations and explanations thereof will be omitted.

[0015] Furthermore, in each of the above embodiments, the crank gear 10, cam gears 20, 22 of the engine shown in FIG. and governor gear 30, but regarding power transmission devices other than the engine This invention can also be applied and is included in this invention.

[0016] In this invention, iron-based materials refer to metals whose main component is iron. aluminum castings refers to castings whose main component is aluminum. As the resin material, for example, 6- Products made of synthetic resins such as nylon mixed with aromatic polyamide fibers or glass fibers. However, the present invention is not limited to these. Each of the gears 10, 20, 22, and 30 uses a helical gear, a helical gear, or a spur gear. No. In this embodiment, the first cam gear 20 and the second cam gear 22 are gears of the same shape. , may be gears of different shapes, modules.

[0017]

[Effect of the idea]

As explained above, according to this invention, the first gear made of iron-based material is made of resin. The gears are engaged, and the second gear made of resin material is engaged with the iron gear. As each gear is pressed into contact with the resin material and iron material, the noise is reduced. In both cases, the resin material can be freely selected in consideration of cost and heat resistance. In addition, in one gear device, the first gear is made of iron-based material and the first gear is made of resin-based material. For example, the crank gear and the second gear are connected concentrically adjacent to each other. When used as a cam gear that meshes with the governor gear, the crank gear should be made of iron. This allows even a small crank gear to have great rigidity. Ru.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a part of a gear device according to a first embodiment of the invention.

FIG. 2 is a sectional view of a camshaft showing a second embodiment.

FIG. 3 is a sectional view of a camshaft showing a third embodiment.

FIG. 4 is a schematic diagram showing a conventional gear train.

FIG. 5 is a schematic diagram showing another conventional example.

FIG. 6 is a schematic diagram showing a gear train not included in this invention.

[Explanation of symbols]

20...First (cam) gear made of iron-based material, 22...Second (cam) gear made of resin-based material

Claims (1)

[Scope of utility model registration request] 1. A gear device in which a first gear made of an iron-based material and a second gear made of a resin-based material are joined concentrically and adjacently.