JPH11201238A - Silent chain and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silent chain and its manufacturing method which improves fatigue strength and static breaking force and lessens elongation of a chain. SOLUTION: By using the pitch Pg of a guide link plate 5 which is larger than the pitch Pi of inner link plates 1a and 1b by a prescribed amount, a larger load is applied on the inner link plate 1b in a guide link line than on the inner link plate 1a in an inner link line in pre-loading. The inner link plate 1b in the guide link line is made to be a closed state to a pin by a pitch difference ΔP (=Pg-Pi). The prescribed pre-load acts so that the pitch of the inner link plates 1a and 1b and the pitch of the guide link plate 5 are made to be almost identical.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silent chain mainly used for power transmission, and more particularly to a silent chain suitable for use as an engine timing (cam) chain and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, a silent chain includes an inner link plate having a pair of crotch-shaped teeth meshing with sprocket teeth, and a guide link plate that guides the chain by contacting the side surfaces of the sprocket teeth. A guide link row in which the guide link plates are arranged on both sides and an inner link row consisting of only the inner link plates are alternately connected by pins so as to be endless. The inner link plate has a pair of teeth protruding in the inner diameter direction regardless of whether the inner link plate is engaged with the sprocket teeth inside (inner thigh) or outside (outer thigh). Thus, a relatively deep cut is formed between the pair of teeth.

[0003] On the other hand, the guide link plate cannot be provided with the above-mentioned cut due to contact with the sprocket tooth side surface, and has a structure having a higher tensile strength than the inner link plate. For this reason, conventionally, the guide link plate is provided with a notch in the outer diameter direction, or a thinner plate than the inner link plate is used so that the difference in strength from the inner link plate is reduced. ing.

[0004]

Conventionally, in a silent chain as well as a roller chain, a tension preload (prestress) exceeding a yield load is applied to an assembled chain so that a pin hole portion, a cut portion and the like are not provided. A residual stress is generated in a portion where stress concentration is likely to occur, thereby improving the fatigue strength (see Japanese Patent Application Laid-Open No. 2-278040 and Japanese Patent No. 26326).

In the silent chain, since the link plates are alternately connected even in the horizontal row, the number of plates in the guide link row is one more than that in the inner link row. For example, as shown in FIG. 9, when two inner link plates 1a, 1a and one inner link plate 1b are alternately connected by pins 2, an inner link consisting of only two inner link plates is provided. The guide link row 6 having the guide link plates 5 (and one inner link plate 1b and the inner link plate is referred to as a center link plate) on both sides of the row 3 has one more link plate.

Therefore, the preload F is applied to the silent chain having two inner link rows 3 and three guide link rows 6.
Works, the link plate 1a of the inner link row
Preferably, a load of (1/2) F acts on the center link plate 1b of the guide link row, and a load of (1/2) F acts on the guide link plate 5 as described above. Even if the strength of the guide link plate is reduced, it is difficult to set the rigidity (Young's modulus) of the guide link plate to about 1/2 of that of the inner link plate.

Further, if the rigidity coefficient of the guide link plate is reduced by using a material having a hardness lower than that of the inner link plate, reducing the thickness of the plate, or forming a deep cut in the upper surface, the fatigue strength is reduced. In addition, the guide link plate has an extremely small static breaking load (tensile strength) as compared with the inner link plate, and may be broken when an overload is applied, such as when the engine is started. May also increase.

Therefore, the present invention increases the pitch of the guide link plates with respect to the inner link plates by a predetermined amount and applies a large load to the inner link plates (center link plates) of the guide link row when applying a preload. Accordingly, it is an object of the present invention to provide a silent chain and a method for manufacturing the same, which solve the above-described problems.

[0009]

According to a first aspect of the present invention, there is provided an inner link row (3) comprising a plurality of inner link plates (1a) having a pair of teeth (12, 12) on an inner diameter side; A guide link row (6) composed of guide link plates (5, 5) arranged on both sides and the inner link plate (1b) arranged between the guide link plates is alternately arranged with pins (2). In the connected silent chain (10), the pitch (Pg) of the guide link plates is larger than the pitch (Pi) of the inner link plates by a predetermined amount (ΔP). The inner link plate (1b) of the guide link row (6) is fastened to the pin (2) and the inner link plate is in a state after a predetermined preload is applied. A silent chain, wherein the pitch of the link plates and the pitch of the guide link plates are substantially equal.

According to a second aspect of the present invention, there is provided an inner link row (3) comprising a plurality of inner link plates (1a) having a pair of teeth (12, 12) on the inner diameter side, and guides arranged on both sides. A silent chain formed by alternately connecting a link plate (5, 5) and a guide link row (6) including the inner link plate (1b) disposed between the guide link plates with a pin (2). In the manufacturing method of (1), the pitch (Pg) of the guide link plate is equal to the pitch (Pg) of the inner link plate.
i) By using the one larger by a predetermined amount (ΔP) than the inner link (1b) of the inner link row in the inner link plate (1b) of the guide link row during preloading.
a) applying a large load as compared to a), and applying a predetermined preload so that the pitch of the inner link plate and the pitch of the guide link plate are substantially equal to each other. is there.

According to a third aspect of the present invention, the guide link plate (5) and the inner link plate (1a, 1
The pitch difference (ΔP) of b) is set based on a correction deformation in a state where the predetermined load in the elastic region is applied to the inner link plate and then the predetermined load is removed.
A method of manufacturing the silent chain according to claim 2 or the silent chain according to claim 2.

According to a fourth aspect of the present invention, the space between the pair of pin holes (15, 15) of the guide link plate (5) is Lg, the hole diameter is Dg, and the inner link plates (1a, 1b) are provided. ), The distance between the outside of the pair of pin holes (11, 11) is Li and the diameter of the pin (2) is Dp, the pitch difference ΔP between the guide link plate and the inner link plate is ΔP = (Lg− Dg)-(Li-D
p) and ΔP / P is in the range of 0.003 to 0.006, where P is the chain pitch after the preload. A silent chain or a method of manufacturing the same.

According to a fifth aspect of the present invention, the guide link plate (5) has its bottom surface (d) connected to the outside diameter end of the pair of pin holes (15, 15) on its outside diameter side. Line (l)
5. The silent chain according to claim 1, further comprising: a shallow cut (16) substantially corresponding to the outer diameter of the silent chain.

[0014]

FIG. 1 shows a silent chain 10 according to an embodiment of the present invention, and an inner link row 3 composed of two inner link plates 1a, 1a, and one inner link plate (center plate). 1b and guide link row 6 composed of guide link plates 5 and 5 on both sides
Are alternately connected by pins 2 to form an endless shape.

The inner link plates 1a and 1b are shown in FIG.
As shown in FIG. 1A, a pair of pin holes 11, 11 and a pair of teeth 12, 12 protruding inwardly are provided, and these teeth 12, 12 have a relatively deep cut therebetween. 13 is formed into a forked shape, and its inner surface (inner thigh) a, a engages with a sprocket tooth, or the outer surface (outer crotch) b, b of an adjacent inner link plate tooth
Engages with the sprocket teeth.

The guide link plate 5 corresponds to FIG.
As shown in FIG. 3B, the inner link plate has a pair of pin holes 15 and 15, the front and rear side surfaces of which have substantially the same shape as the outer side surface b of the inner link plate, and the inner side of which has an arcuate lower surface. c, and a shallow notch having a bottom surface d at the center portion on the outer diameter side which substantially coincides with the line 1 connecting the upper end (outer diameter side end) of the pin hole or is located slightly on the outer diameter side. 16
Are formed. Further, the pin 2 has a circular cross-section, and as shown in FIG. 1A, the thickness of the guide link plate 5 is 0.7 to 0.1 with respect to the thickness t of the inner link plates 1a and 1b. 8t.

The inner link plates 1a,
1b and the guide link plate 5 are both 1
Although it has a pair of holes 11 and 15, the hole diameter and the pitch are different from each other. That is, the hole diameter Dg of the guide link plate 5
Is slightly smaller than the diameter Dp of the pin 2 and the hole diameter Pi of the inner link plates 1a and 1b is slightly larger than the diameter Dp of the pin 2 (Dg <Dp <Di).
The pin 2 is press-fitted into the hole 15 of the guide link plate to be in a tight fit (fitting) state, and the hole 11 of the inner link plate is rotatable with respect to the pin 2, that is, is in a loosely fitted state. .

Further, as shown in FIGS. 2A and 2B, the pitch Pg of the guide link plate 5 is set slightly larger than the pitch Pi of the inner link plates 1a and 1b (Pg> Pi). In addition, the pitch Pg of the guide link plate is set such that the outer interval between the pair of holes 15 is Lg.
Where Pg = Lg−Dg, where Dg is the hole diameter, and the pitch Pi of the inner link plate is Pi = Pi, where Dp is Dp, the outer space between the pair of holes 11, 11 is Li. It is determined by Li-Dp. The difference ΔP between the pitches of the two link plates (= Pg−Pi)
Is [ΔP / P] = 0.003 to 0.006, where P is the chain pitch after preloading, that is, the nominal chain pitch.
, Preferably about 0.005. As an example, when the nominal chain pitch is 6.35 [mm] (0.4 inches), the pitch difference ΔP is approximately 0.02 to 0.
It is set in the range of 04 [mm], preferably 0.03 [mm].

FIG. 3 shows the inner link plate 1a,
1b is a schematic plan view of the silent chain 10 in which the relationship of 1b is emphasized, and in order to facilitate understanding that the center link plate is in a tightly fitted (fastened) state, the pin holes and the curvature of the pin are emphasized and enlarged. Is shown.

The inner link plates 1a and 1b are commonly used for the inner link row 3 and the guide link row 6, and the inner link plates 1a and 1b are loosely fitted to the pin 2, that is, the diameter Pi of the pin hole 11 is smaller. The guide link plate 5 is larger than the diameter Dp of the pin 2 and the pin hole 15 is fitted in the pin hole 15, that is, the hole diameter Dg is smaller than the pin diameter Dp, and the pin 2 and the guide link plate 5 are press-fitted and caulked.
Is in a fixed state.

The pitch P of the guide link plate
g is larger by a predetermined amount than the pitch Pi of the inner link plates, so that in the guide link row 6, when the pins 2 are inserted, the center link plate (the center inner link plate) 1b is slightly Pin hole 1 with bending
5, and the center link plate 1b and the pin 2 are integrally fixed as in the press-fitting. Since the inner link row 3 is composed of only the inner link plate 1a, the relationship between the pin 2 and the inner link plate is rotatable and does not hinder the bending of the chain.

As described above, the inner link plates 1a and 1b and the guide link plates 5 having different pitches are provided.
Are connected and assembled by pins 2. The silent chain 10 including the assembled inner link row 3 and guide link row 6 is subjected to a preload (prestress) consisting of a predetermined load. Preferably, the preload is applied to the inner link plate by about 50 to 70 [%] of the breaking load, and optimally 65 [%]. Therefore, a load obtained by multiplying the load by the number of plates in the inner link row is applied. Preload. In this embodiment (chain pitch 6.35 [mm]), the static breaking load of the inner link plate is 366.
[Kgf], the preload is 366 to 513 [K
gf], preferably 450 to 476 [Kgf].

FIG. 4 is a diagram showing a load-elongation diagram of a single link plate, and FIG.
a, 1b, and (B) show the guide link plate 5.
As is clear from this figure, the guide link plate has a lower static break load but a higher rigidity (coefficient) than the inner link plate. Further, in the inner link plate, a portion marked by X in FIG. 4A is remarkably shown, and a predetermined load (for example, 227 [Kgf]) which does not reach the yield load (elastic region) is applied. Then, when the load is removed, the correction deformation indicated by X occurs. This is considered to be caused by the conformation due to the contact between the pin hole 11 and the pin 2 and the correction caused by the shape of the inner link plate having the teeth 12. In the case of this embodiment, the correction deformation amount is about 0.04 [mm].

Therefore, in the above embodiment, a predetermined preload (450 [Kgf]) is applied by changing the pitch of the guide link plate so that a correction deformation of 0.04 [mm] occurs in the center link plate 1b. An experiment was conducted, and the results are shown in FIG. In FIG. 5, the horizontal axis represents the above-described pitch difference ΔP, that is, a value (Pg−Pi) obtained by subtracting the pitch Pi of the inner link plate from the pitch Pg of the guide link plate before preload, and the vertical axis represents the center link plate. 1b shows the correction deformation amount [mm], from which the pitch difference ΔP at which the correction deformation is about 0.04 [mm] is obtained.
Is found to be 0.03 [mm].
In the case of the example (chain pitch 6.35 [mm]), the guide link plate pitch was set to be longer than the inner link plate pitch by 0.03 [mm].

In the above embodiment, the case of two inner link rows and three guide link rows (2.times.3) has been shown. However, the number of link plates is large (for example, 3.times.4, 4.times.5). )
Similarly, the pitch of the guide link plate is set to be larger than the inner link plate by a predetermined amount. Even in the multi-row silent chain, the silent chain of the above embodiment (2 × 3
Even if the pitch difference ΔP is set to 0.03 [mm] in the same manner as in the first embodiment, the amount of change in the pitch between the center side plate and both side plates in the inner link row and the change in the center inner plate and the guide link plate in the guide link row It was experimentally confirmed that the amount was within a predetermined range (0.01 [mm]). Therefore, in the multi-row chain, it is possible to use the same guide link plate as that of the 2 × 3 reference chains.

Theoretically, when the number of plates Mg in the guide link row and the number of plates Mi in the inner link row are considered, the above equation is as follows. That is, (ΔP
/ P) · (Mg / Mi) is in the range of 0.002 to 0.004, and 0.003 is the optimum value.

It should be noted that the present invention is not limited to the chain pitch shown in the embodiment, but can be applied to other pitches as well, and the guide link plate as shown in FIG. The shape of the cut 26 is not limited to the shape, and as shown in FIG. 6 (A), the upper cut 26 is made deep so that its bottom surface d substantially coincides with the center line l ′ of the pair of pin holes 15, 15. Guide link plate 5 'with low coefficient
6B. As shown in FIG. 6B, the present invention can also be applied to a structure using a guide link plate 5 'having a normal shape without a cut, and further, any shape and material. The present invention can be similarly applied to a silent chain using a link plate having a plate thickness.

Next, a description will be given of experimental results in which the above-described embodiment is compared with another silent chain.
FIGS. 7 and 8 show the results of experiments in which the silent chain of the above-described embodiment was stretched over large and small sprockets, a part of which was lubricated in an oil path in an oil bath, and the chain was driven with a predetermined tension.

FIG. 7 is a wear test result comparing the guide link plate of the prior art in which the rigidity of the guide link plate is significantly reduced (dotted line) and that of the above embodiment of the present invention (solid line). It can be seen that the embodiment has a small elongation even after the drive time elapses. FIG. 8 is the same as FIG.
This is an actual driving fatigue test comparing a silent chain using the guide link plate shown in (A) (however, a pitch difference ΔP = 0) with a chain having a pitch difference according to the present embodiment. Actual driving fatigue strength is about 1
It can be seen that 3% has been improved.

[0030]

As described above, according to the present invention,
By making the pitch of the guide link plates larger by a predetermined amount than the pitch of the inner link plates, a preload (prestress) is concentrated on the inner link plates of the guide link row, and the guide link row and the inner link row after the preload are applied. And the pitch are substantially the same, so there is no need for an unreasonable design that drastically lowers the rigidity of the guide link plate, the fatigue strength of the silent chain can be increased, and the static breaking load can be increased. Further, it is possible to improve the safety factor against the chain tension at the time of overload acting at the time of starting the engine, to further reduce the elongation of the chain, and to make it unnecessary to use the hydraulic tensioner or the like.

In addition, by applying an appropriate preload to the chain, a residual stress is applied to a stress concentrated portion, and the pitch of the chain during meshing is eliminated, so that a silent chain having durability and meshing accuracy can be obtained. Performance and reliability can be improved.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing an embodiment according to the present invention, wherein FIG. 1A is a plan view partially cross-sectioned, and FIG.

FIG. 2A is a side view showing an inner link plate used in the embodiment, and FIG. 2B is a side view showing a guide link plate.

FIG. 3 is a schematic plan cross-sectional view of a silent chain in which the basic principle according to the present invention is adjusted and enlarged to show the basic principle.

FIG. 4 is a load-elongation diagram of the link plate alone according to the embodiment, wherein (A) shows an inner link plate and (B) shows a guide link plate.

FIG. 5 is a diagram illustrating a relationship between a pitch difference and a correction amount of a center link plate when a predetermined preload is applied to set a pitch difference between a guide link plate and an inner link plate.

FIG. 6 is a side view of a guide link plate showing another application example of the present invention, wherein FIG.
(B) shows the case where no cut is provided.

FIG. 7 is a diagram showing the results of a wear test comparing the present embodiment with other chains.

FIG. 8 is a diagram showing the results of an actual driving fatigue strength test comparing this example with other chains.

FIG. 9 is a schematic plan view showing a state in which a preload is applied to a silent chain.

[Explanation of symbols]

1a Inner link plate 1b Inner link plate (center link plate) 2 pins 3 Inner link row 5 (5 ', 5 ") Guide link plate 6 Guide link row 10 Silent chain 11 Pin hole 12 Teeth 13 Cut 15 Pin hole 16 Shallow cut

Claims (5)

[Claims] 1. An inner link row including a plurality of inner link plates having a pair of teeth on an inner diameter side, guide link plates disposed on both sides, and the inner link plate disposed between the guide link plates. And a guide chain, wherein the pitch of the guide link plate is larger than the pitch of the inner link plate by a predetermined amount. Wherein the pitch of the inner link plate and the pitch of the guide link plate after applying a predetermined preload are substantially equal to each other. Silent chain to do. 2. An inner link row comprising a plurality of inner link plates having a pair of teeth on an inner diameter side, guide link plates disposed on both sides, and the inner link plate disposed between the guide link plates. In the method of manufacturing a silent chain in which the guide link plate and the guide link plate are alternately connected by pins, the pitch of the guide link plate is larger than the pitch of the inner link plate by a predetermined amount, so that the A large load is applied to the inner link plate of the guide link row as compared with the inner link plate of the inner link row, and a predetermined preload is applied so that the pitch of the inner link plate and the pitch of the guide link plate become substantially equal. A silent chain manufacturing method Law. 3. A pitch difference between the guide link plate and the inner link plate is set based on a correction deformation in a state where the predetermined load in the elastic region is applied to the inner link plate and then the predetermined load is removed. A method for manufacturing the silent chain according to claim 1 or the silent chain according to claim 2. 4. The distance outside the pair of pin holes of the guide link plate is Lg, the hole diameter is Dg, the distance outside the pair of pin holes of the inner link plate is Li, and the diameter of the pin is Dp. Then, the pitch difference ΔP between the guide link plate and the inner link plate is ΔP = (Lg−Dg) − (Li−Dp), and when the chain pitch after the preload is P, ΔP / P becomes The silent chain or the method for manufacturing the silent chain according to claim 1, wherein the silent chain is in a range of 0.003 to 0.006. 5. A shallow notch on the outer diameter side of the guide link plate, the bottom surface of which is substantially coincident with a line connecting the outer diameter ends of the pair of pin holes or located on the outer diameter side. The silent chain according to any one of claims 1 to 4, or a method for manufacturing the silent chain.