JPH0320145A - Auto-tensioner - Google Patents

Abstract

PURPOSE:To prevent any incovenience such as a tooth skip phenomenon or the like in a toothed belt from occurring without fail by locking each seal member to outer parts of fixed side plates in between, and interrupting a space between adjacent rocking side plates and another space in a second serration groove part respectively. CONSTITUTION:Seal members 17, 17 formed in ring-form as a whole are pinched and locked to parts existing at the more outside than each peripheral edge of fixed side plates 10, 10 in space between rocking side plates 11, 11 adjacent with each other, in these plates 11, 11 supported at the inside of a rocking member 6. Consequently, a space existing in these adjacent rocking ride plates 11 and 11 and another space existing a part of a second serration groove 13 formed on an inner circumferential surface of this rocking member 6 are made into a state of being interrupted. Accordingly, an amount of viscous fluid existing in a fine clearance part between both sides of the fixed side plates 10, 10 and the rocking side plates 11, 11 are prevented from being decreased, so that such a function as making a tension pulley so as not to suddenly retracted from a timing belt is sufficiently performed for a long period of time.

Description

[Detailed Description of the Invention] (Field of Application in Industry A) The auto tensioner according to the present invention applies appropriate tension to the timing belt of an automobile engine or a belt for driving auxiliary equipment such as an alternator or compressor. Used for granting. (Prior art) The camshaft of an OHC type or DOHC type engine is
In order to rotate and drive in synchronization with the crankshaft, a drive mechanism using a tie belt 1 as shown in Fig. 2 is widely used. In FIG. 2, 2 is a drive pulley that is rotationally driven by the engine crankshaft, 3 is a driven pulley fixed to the end of the camshaft, and 4 is a tie belt 1.
This is a tension pulley to apply appropriate tension to the The tension pulley 4 is pivotally supported around a swinging member 6 that swings around a fixed shaft 5, as shown in detail in FIGS. One end of a tension spring 8 is connected to the distal end of the arm piece 7 whose base end is fixed to the swinging member 6, and by elastically pressing the tension pulley 4 toward the timing belt 1, The tension of the timing belt 1 is always kept constant regardless of dimensional changes in the timing belt 1 due to temperature changes or vibrations caused by engine operation. By the way, when the engine is stopped, etc., the tie main belt 1
The tension may increase locally and temporarily. In such a case, when the tension pulley 4 is retracted from the tie belt 1, other parts of the timing belt 1 may
There will be a part where the tension is extremely low, and there is a risk that a so-called tooth skipping phenomenon will occur between the tying belt 1 and the toothed pulleys (both driving and driven pulleys 2 and 3) in this part.
y Ru. In order to prevent such a tooth skipping phenomenon from occurring, a multi-plate damper mechanism has been conventionally provided between the fixed shaft 5 and the swinging member 6, as disclosed in, for example, Japanese Patent Application Laid-Open No. 63-180759. is provided to prevent the tension pulley 4 from immediately retracting even if the tension of the timing belt 1 increases suddenly in some areas. That is, as shown in FIG. 4, in the space 9 existing between the outer circumferential surface of the fixed shaft 5 and the inner circumferential surface of the swinging member 6, there are a plurality of sheets whose inner circumferential edges are fixed to the fixed shaft 5. Fixed side flat plates 10, 1o and a plurality of swinging side flat plates 11, 11 whose outer peripheral edges are fixed to the inner circumferential surface of the swinging member 6 are arranged alternately, and a viscous fluid such as oil is placed in the space 9. By enclosing it, a damper mechanism is constructed. The side surfaces of the fixed side flat plates 10, 10 and the side surfaces of the swing side flat plates ti, tt are opposed to each other through a narrow gap, and since viscous fluid exists in this gap, both flat plates Sudden displacement between 10 and 11 is prevented by the shearing force applied to the viscous fluid existing in the gap, and as a result, even if the tension of the timing belt 1 increases suddenly in some areas, the tension boot 4 will not be evacuated immediately. By the way, in order to have a sufficient function to prevent the tension pulley 4 from suddenly retreating from the timing belt 1,
It is necessary that the side surfaces of the fixed side flat plates 10, 1o and the side surfaces of the swing side flat plates 11, 11 are opposed to each other with a narrow gap formed as described above. For this reason, in the past, spacers were provided between each of the flat plates 10 and 11 to position each of the flat plates io and z, and a narrow gap was formed between the adjacent flat plates 10 and 11. When positioning each of the flat plates 10 and 11 in this manner, it is necessary to strictly control the thickness dimensions of the base plate and the flat plates 10 and 11, and an increase in manufacturing costs can be avoided.
I couldn't. For this reason, as shown in FIG. 5, the fixed side flat plates 10, 1
0, and the outer peripheral edges of the swing-side flat plates 11, 11 are brought into serration engagement with the second serration groove 13 formed on the inner peripheral surface of the swinging member 6. is being carried out. The fixed side flat plates 10 are arranged alternately.
, 1o and the swinging side flat plates 11, 11, since viscous fluid exists, the fixed ring 14 fitted and fixed to the inner peripheral surface of the swinging member 6 lightly presses both flat plates 10, 11 together. Even in this case, an extremely narrow gap filled with viscous fluid is formed between the side surfaces of both flat plates 10 and 11.
Even if the thickness dimensions of both the flat plates 10, 11 are not so strictly regulated, the side surfaces of the plurality of fixed side flat plates 10, 10 and the side surfaces of the swing side flat plates 11, 11 can be made extremely thin as described above. By facing each other through a narrow gap, the tension pulley 4 can sufficiently function to prevent the tension pulley 4 from suddenly retreating from the tie belt 1. (Problem to be Solved by the Invention) However, as described above, the fixed side flat plates 10, 10 and the swinging side flat plates 11, 11 are engaged with the fixed shaft 5 or the swinging member 6 through serrations. In this case, new inconveniences will arise as described below.

That is, in order to sufficiently perform the function of preventing the tension pulley 4 from suddenly retracting from the timing belt 1, the side surfaces of the fixed side flat plate 10, 10 and the swinging side flat plates 11, 11 must be
It is necessary that the small gap between the side surface and the surface of the product be filled with a viscous fluid such as oil. However, as a result of research by the present inventor, the fixed side flat plates 10, 10 and the swinging side flat plate 11 were
, 11 are slightly displaced, the viscous fluid existing between the side surfaces of both flat plates 10 and 11 gradually moves outward C, and the second serration groove formed on the inner circumferential surface of the swinging member 6. I found out that it leaked to part 13. As a result of the viscous fluid flowing out in this way, the fixed side flat plates 10, 1
When the viscous fluid such as oil that exists in the minute gap between the side surface of the 0 and the side surface of the swinging side flat plates 11 and 11 decreases, the tension pulley 4 is prevented from suddenly retreating from the tie belt 1. The functions that should be carried out will no longer be performed adequately.

The space 9 formed between the outer circumferential surface of the fixed shaft 5 and the inner circumferential surface of the swinging member 6 and containing the fixed side flat plates 10, 10 and the swinging side flat plates 11, 11 is completely filled with viscous fluid. h, it is possible to prevent the viscous fluid in the gap from decreasing, but it is difficult to completely fill the space 9 with the viscous fluid, and it is possible to avoid creating a void portion where the viscous fluid exists in the space 9. I can't. On the other hand, since the amount of viscous fluid that exists in the gap is extremely small, the viscous fluid that exists in the gap moves to the gap and prevents the amount of viscous fluid in the gap from decreasing. It's difficult to do.

The autotensioner of the present invention eliminates the above-mentioned disadvantages.

(Means for Solving the Problems) The autotensioner of the present invention has a fixed shaft, a first serration structure formed on the outer circumferential surface of the fixed shaft, and a circular structure, which is similar to the conventional autotensioner described above. a plurality of fixed side flat plates formed in a ring shape, each having an inner peripheral edge serrated engaged with the first serration groove; and a plurality of fixed side flat plates having at least a base formed in a cylindrical shape and supported rotatably around a fixed shaft. A swing member and a second serration groove formed on the inner peripheral surface of the swing member are each located between the fixed side flat plate, and each outer peripheral edge is serrated into the second serration groove. A plurality of engaged swing-side flat plates, a k-tension pulley supported by a pivot provided in parallel to the fixed shaft on a part of the swing member, and a member to which tension is applied to the tension pulley. It consists of a spring that presses towards the

Furthermore, in the autotensioner of the present invention, a sealing member formed entirely in an annular shape is clamped and fixed between adjacent swinging side flat plates at a portion that exists outside the outer peripheral edge of the fixed side flat plate. By doing so, the space existing between the adjacent swinging side flat plates is cut off from the space existing in the second serration groove portion. (Function) The autotensioner of the present invention configured as described above can apply appropriate tension to a belt such as an engine tie belt, or when the tension of this belt increases suddenly in a part. The action itself when holding down this belt is similar to that of the conventional auto tensioner described above.

However, in the case of the auto-tensioner of the present invention, the movement of the viscous fluid that exists in the minute gap between the side surface of the fixed side flat plate and the side surface of the swinging side flat plate causes the clamping and fixing between both flat plates. This prevents the amount of viscous fluid present in the minute gap from decreasing, and prevents the tension pulley from suddenly retreating from the timing belt for a long period of time. It is done enough.

(Example) Next, the present invention will be explained in more detail by explaining the illustrated example. FIG. 1 is an enlarged sectional view corresponding to section A in FIG. 4, showing an embodiment of the present invention. 5 is a fixed shaft, with a large diameter portion 5a at the base end (right end in Fig. 1).
It has a cylindrical shape, and when the auto tensioner is in use, it is fixed to the front of the engine's cylinder block (in the case of an auto tensioner for a timing belt) with a bolt (not shown). A first serration B groove 12 is formed on the outer peripheral surface of the fixed shaft 5, and a plurality of fixed side flat plates 10, 1 each formed in a circular ring shape are formed in the first serration groove 12.
The inner peripheral edge of 0 is engaged with the ceresi B. That is, the plurality of fixed side flat plates to, to are arranged around the fixed shaft 5,
Although it can be freely displaced in the axial direction (horizontal direction in FIG. 1), it is supported in a non-rotatable manner with respect to the shaft 5. Reference numeral 6 denotes a swinging member having a cylindrical shape as a whole and rotatably supported around the fixed shaft 5, and a second serration groove l3&: formed on the inner peripheral surface of the swinging member 6. , a plurality of swing-side flat plates 11, each of which is shaped like a ring;
The outer peripheral edges of 11 are engaged. That is, the plurality of swing-side flat plates 11, 11 are supported non-rotatably relative to the swing member 6. The front end C of the swinging member 6 is parallel to the fixed shaft 5, but is provided with a cylindrical portion 15 (see FIG. 4) eccentric to the fixed shaft 5, and this cylindrical portion 15 functions as a pivot. A tension roller 4 is supported around the periphery via a rolling bearing 16. However, if it is necessary to ensure a sufficient amount of displacement (stroke) of the tension booth 4, the swing member 6
An arm protrudes from the outer peripheral surface of the base, and a tension pulley 4 is supported at the tip of the arm via a pivot. Further, one end of a tension spring 8 is coupled to the distal end of an arm piece 7 (FIG. 4) externally fitted and fixed to the base end of the swinging member 6.
A tension booth 4 imparts elasticity in the torsional direction to the swinging member 6 and is rotatably supported around the cylindrical portion 15.
On the other hand, elasticity is imparted to the tensioner 4 to press it towards the tie belt 1 (Fig. 2) to which tension is to be applied. The above-mentioned configuration is the same as that of the conventional auto tensioner described above, but furthermore, in the auto tensioner of the present invention, a plurality of swinging members supported inside the swinging member 6 are used. A sealing member formed entirely in an annular shape in a portion of the movable side flat plates 11, 11 that is located between the adjacent swinging side flat plates 11, 11 and located outside the outer periphery of the stationary side flat plates 10, 10. 17, 17 are clamped and fixed. Each seal member 17, 17 is made of a flat plate made of metal or synthetic resin, and the thickness dimension of each seal member 17, 17 is determined by the fixed size between the adjacent swing side flat plates 11, 11. side plate 1
It is formed slightly larger than the thickness dimension of 0 and 10.

As a result, the space existing between the adjacent swing-side flat plates 11, 11 and the space existing in the second serration groove 13 formed on the inner peripheral surface of the swing member 6 are cut off. It becomes a state. In the case of this embodiment, the seal members 17, 1
It is necessary to make the thickness of 7 slightly larger than the thickness of fixed side flat plates to, to, but this level of dimensional control is much easier than when positioning each flat plate 10 and 11 using spacers. I can do it.

The auto-tensioner of the present invention, which is designed as described above, can apply appropriate tension to belts such as the engine tie belt 1, or when the tension of the timing belt 1 etc. suddenly increases locally. Niko tie belt 1
The action of suppressing the tension is the same as that of the conventional auto tensioner described above. However, in the case of the auto tensioner of the present invention, the gap between the side surfaces of the fixed side flat plates 10, 10 supported on the outside of the fixed shaft 5 and the side surfaces of the swing side flat plates 1l, 11 supported on the inside of the swinging member 6 is The outward movement of viscous fluid existing in minute gaps is
A sealing member 17 clamped and fixed between both flat plates 10, 10.
This is prevented by e. For this reason, the amount of viscous fluid existing in the micro grooves is prevented from decreasing, and the function of preventing the tension pulley 4 from suddenly retreating from the timing belt 1 is sufficiently maintained over a long period of time. It is done. In addition, by clamping and fixing between the fixed side flat plate 10 and the swinging side flat plate l1, the sealing member is used to prevent the viscous fluid existing between the two flat plates 10 and 11 from moving outward. ,
In addition to the flat, incompressible ones mentioned above, O-rings,
Elastic materials such as rubber plates can also be used. In addition, when the timing belt 1 becomes slack, the tension pulley 4 is immediately made to follow the timing belt 1, and when the tension of the timing belt 1 suddenly increases, the tension pulley 4 causes the timing belt 1 to An intermediate ring is placed around the fixed shaft 5 so as to suppress the fixed shaft 5.
Japanese Patent Application No. 63-229829 discloses an invention in which a one-way clutch mechanism is provided between the fixed shaft 5 and the intermediate wheel, and the fixed shaft 5 is rotatably fitted around the center of the wheel. When combined with the invention, the first serration groove 12 is formed on the outer circumferential surface of the intermediate ring, and the fixed side flat plate to
, tt are supported around this intermediate ring. (Effects of the Invention) Since the autotensioner of the present invention is constructed and operates as described above, the fixed side flat plate and the swinging side flat plate that constitute the viscous damper mechanism are mutually connected for a long period of time. It is possible to secure a sufficient amount of viscous fluid, and it is possible to reliably prevent problems such as tooth skipping of toothed belts.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, and is an enlarged cross-sectional view corresponding to A-row in Fig. 4, Fig. 2 is a front view of a belt drive mechanism equipped with an auto-tensioner, and Fig. 3 is an enlarged view of only the auto-tensioner. 4 is a sectional view taken along line B-B in FIG. 3.
FIG. 5 is an enlarged sectional view corresponding to section A in FIG. 4, showing a second example of the structure of a conventional autotensioner. 1: Timing belt, 2: Drive pulley, 3: Follower pulley, 4: Tension pulley, 5: Fixed shaft, 5a: Large diameter part, 6: Swing member, 7: Arm piece, 8: Tension spring, 9: Space, 10: Fixed side flat plate, 1 1: #M moving side flat plate, 1
2: first serration groove, 13: second serration groove, 14: fixed ring, 15: cylindrical part, 16: rolling bearing,
17: Seal member.

Claims (5)

[Claims] (1) A fixed shaft and a first serration groove formed on the outer peripheral surface of the fixed shaft, each of which is formed in a circular ring shape, and the inner peripheral edge of each is serrated engaged with the first serration groove, A plurality of fixed side flat plates, a swinging member having at least a cylindrical base and rotatably supported around a fixed shaft, and a second serration groove formed on the inner peripheral surface of the swinging member. and a plurality of swing-side flat plates, each of which is located between the fixed-side flat plates, and whose outer peripheral edge is serrated engaged with the second serration groove;
In an auto-tensioner comprising a tension pulley supported by a pivot provided in parallel with the fixed shaft on a part of the swinging member, and a spring that presses the tension pulley toward the member to which tension is to be applied. By clamping and fixing a sealing member formed entirely in an annular shape between the adjacent swinging side flat plates, in a portion existing outside the outer periphery of the fixed side flat plate, the adjacent swinging side flat plates can be fixed. An auto tensioner characterized in that the space existing between the two serration grooves and the space existing in the second serration groove portion are isolated from each other. (2) The autotensioner according to claim 1, wherein the sealing member is a flat plate having a thickness slightly larger than the thickness of the fixed side flat plate. (3) The autotensioner according to claim 1, wherein the sealing member is an O-ring. (4) Any one of claims 1 to 3, wherein the first serration groove is formed on the outer circumferential surface of another member that is externally supported on the fixed shaft instead of being directly fixed to the outer circumferential surface of the fixed shaft. Auto tensioner described in the above. (5) The auto tensioner according to any one of claims 1 to 4, wherein the pivot for supporting the tension pulley is a cylindrical portion formed at the tip of the swinging member in an eccentric state with respect to the fixed shaft. Jonah.