JPH081315Y2 - Toothed belt type power transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power transmission device using a toothed belt (also called a timing belt, a synchro belt, or the like).

[Conventional technology]

Conventionally, as this type of toothed belt type power transmission device, for example, there is one as shown in FIGS. That is, a crankshaft sprocket 1 as a toothed belt wheel attached to the crankshaft of an automobile engine is provided, and a pair of vertically installed crankshaft sprockets on both sides of the crankshaft rotate at twice the speed of the crankshaft. Silent shaft sprockets 2 and 3 are provided as toothed belt wheels that are respectively attached to balancer shafts (silent shafts) for vibration reduction.

An endless timing belt (toothed belt) 4 meshing with the sprockets 1 to 3 is wound between the sprockets 1 to 3, whereby the power from the crankshaft is transmitted to the crankshaft sprockets 1. The silent shaft is rotatably driven by being transmitted to the silent shaft via the timing belt 4 and the silent shaft sprockets 2 and 3.

Reference numeral 5 in FIGS. 5 and 6 indicates a tensioner.

[Problems to be solved by the invention]

However, in such a conventional toothed belt type power transmission device, the toothed belt 4 and the toothed belt wheels 1, 2, 3
There is a problem that air noise (so-called mesh noise) is generated due to air being sucked in or discharged by meshing with.

Therefore, an air escape hole 6 (see FIG. 7), an air escape groove, and an air escape notch are formed in the toothed belt 4 and the toothed belt wheels 1, 2, and 3 so that the belt wheel and the belt are engaged with each other during meshing. Although it has been proposed to let the air sandwiched between the meshes escape from the meshing part, such a conventional toothed belt type power transmission device can reduce air noise, but the belt has indentations and scratches. There is a risk that the belt will be damaged, and there is a problem in terms of belt durability.

The present invention is intended to solve such a problem, and to provide a toothed belt type power transmission device capable of reducing air noise and exhibiting excellent belt durability. With the goal.

[Means for solving problems]

Therefore, the toothed belt type driving force transmission device of the present invention includes a toothed belt wheel and a toothed belt that meshes with the toothed belt wheel, and the tooth top portion and the tooth groove portion are formed in the toothed belt wheel. On the other hand, the toothed belt is meshed with the tooth top portion and the tooth groove portion of the toothed belt wheel to form a first
And a tooth groove portion and a tooth crest portion that form the second meshing portion are formed, and at least one axial end portion of the meshing portion of at least one of the first and second meshing portions in the belt moving direction An air escape chamfer that spreads over the whole is formed, and the central portion of the meshing portion sandwiched between the air escape chamfers is formed higher than both air escape chamfers in the entire moving direction of the toothed belt. It is characterized by being done.

[Action]

In the above-mentioned toothed belt type driving force transmission device of the present invention,
A first configuration in which a tooth top portion and a tooth groove portion of a toothed belt wheel engage with a tooth groove portion and a tooth top portion of a toothed belt, respectively.
And at least one of the second meshing portions is formed at both axial end portions of the meshing portion with air-releasing chamfers extending in the entire direction of movement of the belt, and is sandwiched by both air-releasing chamfers. Since the toothed belt and the toothed pulley are in contact with each other at the center portion of the meshing portion and mesh with each other, the meshing timing at the left and right end portions of the belt moving direction and the contact area at the center portion are uniform, and the toothed belt and the toothed belt Keep sufficient transmission force with the attached belt car,
When the toothed belt and the toothed wheel mesh with each other from the chamfered portions on both axial ends of the toothed portion while applying a uniform load to the central portion of the toothed belt and the toothed wheel pulley. The air is released to the outside to reduce air noise. Furthermore, no local load is applied to the belt, so that the belt is not indented or damaged.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show a toothed belt type power transmission device as an embodiment of the present invention, and FIG. Partial perspective view, FIG. 1 (b) is a partial perspective view of the toothed belt, and FIG. 1 (c) is a partial cross-sectional view of the meshing portion between the tooth crest portion of the belt wheel and the tooth groove portion of the belt, FIG. (D)
FIG. 2 is a partial cross-sectional view of a meshing portion between a tooth groove portion of the belt wheel and a tooth top portion of the belt, and FIGS. 2A to 2D show a first modified example of the toothed belt type power transmission device. 2 (a) is a partial perspective view of the belt wheel, FIG. 2 (b) is a partial perspective view of the toothed belt, and FIG. 2 (c) is a tooth top of the belt wheel and teeth of the belt. 2 (d) is a partial cross-sectional view of the meshing portion with the groove portion, and FIG. 2 (d) is a partial cross-sectional view of the meshing portion between the tooth groove portion of the belt wheel and the tooth crest portion of the belt.
FIG. 3D shows a second modification of the toothed belt type power transmission device. FIG. 3A is a partial perspective view of the belt wheel thereof, and FIG. 3B is a portion of the toothed belt thereof. FIG. 3 (c) is a partial cross-sectional view of the meshing portion between the tooth crest portion of the belt wheel and the tooth groove portion of the belt, and FIG. 3 (d) is the tooth groove portion of the belt wheel and the tooth crest portion of the belt. FIG. 4 is a partial cross-sectional view of the meshing portion, and FIG. 4 is a graph for explaining the action thereof,
In the drawings, the same reference numerals indicate almost the same parts.

In the present embodiment as well, a case will be described in which the present invention is applied to a toothed belt type power transmission device for rotationally driving the balancer shaft shown in FIG.

That is, the timing belt 4 is formed with air relief chamfers 10A at both axial end portions of each tooth top 4a, as shown in FIGS. 1 (b) and (d), and each tooth groove portion thereof. As shown in FIGS. 1B and 1C, air escape chamfers 10B are formed at both ends of the axis 4b in the axial direction.

In addition, the sprockets 1, 2 and 3 have their respective tooth tops 1a, 2a and 3a.
As shown in FIGS. 1 (a) and (c), air relief chamfered portions 11A are formed at both axial end portions of each of the tooth groove portions 1b, 2b, 3b, and axially opposite end portions thereof, respectively. First
As shown in FIGS. (A) and (d), air-releasing chamfers 11B are formed respectively.

Therefore, the tooth top portions 1a, 2a, 3a of the sprockets 1 to 3 and the tooth groove portion 4b of the timing belt 4 are meshed with each other to form a first meshing portion, and the tooth groove portions 1b, 2b, 3b of the sprockets 1 to 3 are timing. When the second meshing portion is formed by meshing with the tooth top portion 4a of the belt 4, the two ends of each meshing portion are connected to each other as shown in FIG.
A gap (non-contact portion) as shown in (d) is formed. In addition, in the middle part of the meshing part, the tooth crests 1a to 3a of the sprockets 1 to 3 and the tooth groove part 4b of the timing belt 4 are formed.
And the tooth groove 1b of the sprockets 1 to 3
3b and the tooth top portion 4a of the timing belt 4 are in contact with each other.

Here, the chamfered portions 10A, 10B, 11A and 11B of the timing belt 4 and the sprockets 1 to 3 are all chamfered portions 10 as shown in FIGS. 1 (a) to (d).
A, 10B, 11A, 11B is formed on each tooth top portion 4a and each tooth groove portion 4b, and each tooth top portion 1a, 2a, 3a and each tooth groove portion 1b, 2
b and 3b, a pair of chamfers formed so as to spread over the entire belt moving direction and formed at both ends in the axial direction.
The central portion (meshing portion intermediate portion) of each meshing portion sandwiched between 10A-10A, 10B-10B, 11A-11A, and 11B-11B is formed higher than the chamfered portion in the entire belt moving direction.

Further, each chamfered portion 10A, 10B, 11A, 11B, each chamfered portion 10A, so that an edge is not formed at the boundary between the central portion and the above.
10B, 11A, 11B are connected smoothly to the central part.

The chamfered portions 10A, 10B, 11A, 11B may be flat or curved.

In addition, each tooth groove portion 4b of the timing belt 4 has a second
As shown in FIGS. 2 (b) and 2 (c), without chamfering, air is released to both axial end portions of each tooth top 4a of the timing belt 4 as shown in FIGS. 2 (b) and 2 (d). While forming the chamfered portion 10A, the tooth top portions 1a to 3a of the sprockets 1 to 3a are formed as shown in FIGS.
Without chamfering, each tooth groove part 1b of sprocket 1-3
As shown in FIGS. 2 (a) and 2 (d), air relief chamfers 11A may be formed at both ends in the axial direction of 3b.

In this case, at the meshing portion (second meshing portion) between the tooth groove portions 1b to 3b of the sprockets 1 to 3 and the tooth crest portion 4a of the timing belt 4, the air escape chamfered portions 11B and 10A are provided at both ends in the axial direction. When formed, gaps (non-contact portions) as shown in FIG. 2D are formed at both ends in the axial direction of the meshing portion.

In addition, the middle portion of the meshing portion between the tooth groove portions 1b to 3b of the sprockets 1 to 3 and the tooth top portion 4a of the timing belt 4 is the tooth groove portions 1b to 3b of the sprocket 1 to 3 and the tooth tip portion of the timing belt 4.
4a is in contact.

Further, the meshing portions of the tooth tops 1a to 3a of the sprockets 1 to 3 and the tooth groove portion 4b of the timing belt 4 are in contact with the tooth tops 1a to 3a of the sprockets 1 to the tooth groove portion 4b of the timing belt 4 over the entire width. are doing.

Further, each tooth top portion 4a of the timing belt 4 has a third
As shown in FIGS. 3 (b) and 3 (d), without chamfering, as shown in FIGS. 3 (b) and 3 (c), the air is released to both axial end portions of each tooth groove portion 4b of the timing belt 4. While forming the chamfered portion 10B, the tooth grooves 1b to 3b of the sprockets 1 to 3 are, as shown in FIGS. 3 (a) and 3 (b),
Without chamfering, each tooth top 1a of sprocket 1-3
As shown in FIGS. 3 (a) and 3 (c), air relief chamfers 11A may be formed at both ends of the axial direction of 3a.

In this case, in the meshing portion (first meshing portion) between the tooth crests 1a to 3a of the sprockets 1 to 3 and the tooth groove portion 4b of the timing belt 4, the air escape chamfered portions 11A and 10B are provided at both ends in the axial direction. After being formed, a gap (non-contact portion) as shown in FIG. 3C is formed at both ends in the axial direction of this meshing portion.

In addition, the middle portion of the meshing portion between the tooth tops 1a to 3a of the sprockets 1 to 3 and the tooth groove portion 4b of the timing belt 4 is the tooth top portions 1a to 3a of the sprockets 1 to 3 and the tooth groove portion of the timing belt 4.
4b is in contact.

In addition, the tooth groove portions 1b to 3b of the sprockets 1 to 3 and the tooth top portion 4a of the timing belt 4 are in contact with the tooth groove portions 1b to 3b of the sprocket 1 to 3 and the tooth top portion 4a of the timing belt 4 over the entire width. are doing.

With the above configuration, when the engine is operated and the crankshaft is rotated, the silent shaft sprockets 2 and 3 are rotationally driven via the crankshaft sprocket 1 and the timing belt 4, and the upper and lower silent shafts rotate. The air sandwiched between the timing belts 1 to 3 and the timing belt 4 through the air-releasing chamfers 10A, 10B; 11A, 11B is the axial direction of the meshing portions of the sprockets 1 to 3 and the timing belt 4. Interlocking noise (air noise) because it escapes from both ends to the outside
Can be significantly reduced.

This effect can be confirmed by the graph shown in FIG. In FIG. 4, the characteristic indicated by the symbol a indicates the characteristic obtained by the conventional one without the air escape groove, and the characteristic indicated by the symbol B indicates the characteristic obtained by the present invention having the air escape groove. Therefore, it is understood that the noise level can be reduced by the present invention.

Note that FIG. 4 shows the noise level (dB) measured on the A scale.

In addition, a gap is formed between the sprockets 1 to 3 and the timing belt 4 in the portion where the chamfered portion is formed, but in other portions, the tooth portions of the sprockets 1 to 3 and the timing belt 4 are Since they are in contact with each other and the transition to the chamfer (the boundary between the chamfer and other parts) is formed smoothly, no local load acts on the timing belt 4, As a result, it is possible to sufficiently prevent the timing belt 4 from being indented or being damaged.

Further, even if the air-releasing chamfered portions are formed at both ends of the meshing portion in the axial direction as described above, the reduction of the transmission force is small,
The effect obtained is greater.

When the sprockets 1 to 3 are made of a sintered alloy, the air-releasing chamfered portions 11A and 11B can be formed at the same time when the sprockets are manufactured, so that the number of man-hours required for the processing can be reduced.

Further, it goes without saying that the present toothed belt type power transmission device can be applied to not only a device that transmits power to the balancer shaft but also a device that transmits power to the camshaft and the injection pump.

Furthermore, the shape of the air relief chamfer formed on the timing belt and the sprocket, the chamfer angles θ ₁ , θ _2, etc.
The present invention is not limited to those shown in the above-mentioned embodiment, and an appropriate one is selected according to the shape and application of the timing belt or sprocket.

[Effect of device]

As described above in detail, according to the toothed belt type driving force transmission device of the present invention, the tooth top portion and the tooth groove portion of the toothed belt wheel are engaged with the tooth groove portion and the tooth top portion of the toothed belt, respectively. Of the first and second meshing portions, at least one of the meshing portions is formed at both ends in the axial direction with an air-releasing chamfer that spreads over the entire belt in the moving direction of the belt. Since the toothed belt and the toothed pulley make contact with each other only at the central portion of the meshing portion sandwiched by the chamfered portions, the meshing timing at the left and right end portions in the belt moving direction and the contact area at the central portion become uniform. , The meshing portion while maintaining a sufficient transmission force between the toothed belt and the toothed belt wheel and applying a uniform load to the central portion of the meshing portion of the toothed belt and the toothed belt wheel. The air when the toothed belt and the toothed pulley are engaged with each other can be released to the outside from the chamfered portions at both ends in the axial direction, and as a result, the air noise can be maintained without damaging the belt, that is, while maintaining the durability of the belt. It is possible to obtain the effect of significantly reducing

[Brief description of drawings]

1 to 4 show a toothed belt type power transmission device as an embodiment of the present invention. FIG. 1 (a) is a partial perspective view of the belt wheel, and FIG. 1 (b) is its tooth. FIG. 1 (c) is a partial cross-sectional view of the meshing portion between the tooth top portion of the belt wheel and the tooth groove portion of the belt, and FIG. 1 (d) is the tooth groove portion of the belt wheel and the belt. FIG. 2 is a partial cross-sectional view of a meshing portion with a tooth top portion, and FIGS. 2A to 2D show a first modified example of the toothed belt type power transmission device, and FIG. FIG. 2 (b) is a partial perspective view of a belt wheel, FIG. 2 (b) is a partial perspective view of the toothed belt, and FIG. 2 (c) is a partial cross-sectional view of a meshing portion between the tooth crest portion of the belt wheel and the tooth groove portion of the belt. 2 (d) is a partial cross-sectional view of the meshing portion between the tooth groove portion of the belt wheel and the tooth top portion of the belt, and FIG. 3 (a)-
FIG. 3D shows a second modification of the toothed belt type power transmission device. FIG. 3A is a partial perspective view of the belt wheel thereof, and FIG. 3B is a portion of the toothed belt thereof. FIG. 3 (c) is a partial cross-sectional view of the meshing portion between the tooth crest portion of the belt wheel and the tooth groove portion of the belt, and FIG. 3 (d) is the tooth groove portion of the belt wheel and the tooth crest portion of the belt. FIG. 4 is a partial cross-sectional view of the meshing portion, and FIG. 4 is a graph for explaining the action thereof,
FIG. 5 is an overall configuration diagram of a conventional toothed belt type power transmission device, FIG. 6 is a partial perspective view showing a conventional belt wheel, and FIG. 7 is a partial perspective view showing another conventional belt wheel. 1 ... Crankshaft sprocket (toothed belt wheel), 1a ... Tooth top part, 1b ... Tooth groove part, 2, 3 ... Silent shaft sprocket (toothed belt wheel), 2a, 3a ...
… Tooth top, 2b, 3b …… Tooth groove, 4 …… Timing belt (toothed belt), 4a …… Tooth top, 4b …… Tooth groove, 10A,
10B, 11A, 11B ... Air release chamfer.

Claims (1)

[Scope of utility model registration request] 1. A toothed belt wheel and a toothed belt meshing with the toothed belt wheel, wherein the toothed belt wheel is provided with tooth tops and groove portions, while the toothed belt is provided with the toothed belt. A tooth groove part and a tooth crest part which are respectively meshed with the tooth crest part and the tooth crest part of the vehicle to form first and second meshing parts are formed, and at least one of the first and second meshing parts is the same. Air-releasing chamfers are formed at both ends in the axial direction of the meshing portion, and the air-releasing chamfers that spread in the entire direction of the belt are formed. The center portion of the meshing portion sandwiched between the air-releasing chamfers is the movement of the toothed belt. A toothed belt type power transmission device, characterized in that it is formed higher than both of the air escape chamfers in the entire direction.