JPH0861445A - Auto-tensioner - Google Patents

Abstract

PURPOSE: To prevent the functions of a damper device from deteriorating by allowing no air to exist in a closed space which is filled with a viscous liquid for the purpose of constituting a damper device. CONSTITUTION: A compensating space 28a is provided inside a rocking member 5 and communicated with a closed space 11 by a through hole 27. The level of a liquid in the compensating space 28a is restricted to not lower than the upper end of the closed space 11 so that no air exists within the closed space 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The automatic tensioner according to the present invention is a belt for driving a timing belt of an automobile engine or an auxiliary machine such as an alternator or a compressor (hereinafter, these are collectively referred to simply as "belts"). It is used to give a proper tension to.

[0002]

2. Description of the Related Art A belt 1 for rotationally driving a camshaft of an OHC type or DOHC type engine in synchronization with a crankshaft is provided with an appropriate tension by an auto tensioner 2 as shown in FIGS. Is given. The auto tensioner 2 is configured as shown in FIGS. 4 to 5 by combining the parts as shown in FIG. In FIG. 6 showing the disassembled state, the number of some members is
It is drawn less than in FIG. 5 showing the actual case. or,
The rocking member 5 shown in FIGS. 4 to 5 and the rocking member 5 shown in FIG.
The shapes of the tip end side portions (the left end side portions in FIG. 5 and FIG. 6) of the and are slightly different, but the operation is the same and is substantially the same.

First, the fixing member 3 includes a bolt 16 (FIG. 6).
Thus, it is fixed to the front surface of a cylinder block (not shown) which is a fixed portion. The fixed member 3 is provided with a cylindrical fixed shaft 4, and a swing member 5 is rotatably supported around the fixed shaft 4 via slide bearings 6a and 6b. The outer peripheral surface of the tip end portion (the left end portion in FIGS. 5 to 6) of the swing member 5 constitutes a cylindrical surface eccentric to the fixed shaft 4. A pulley 7 is rotatably supported around the tip of the swing member 5 via a rolling bearing 8 such as a deep groove type ball bearing. A bracket 9 is externally fitted and fixed to the outer peripheral surface of the base end portion (right end portion in FIGS. 5 and 6) of the swinging member 5. An engaging portion 10 is provided on a part of the bracket 9 so as to project outward in the diametrical direction. A tension spring 24 (FIG. 4) is provided between the locking portion 10 and another locking portion provided on the front surface of the cylinder block. The tension spring 24 allows the swing member 5 to move.
In addition, the elastic force is applied in the direction of pressing the pulley 7 toward the belt 1.

Between the outer peripheral surface of the intermediate portion of the fixed member 3 and the inner peripheral surface of the intermediate portion of the swing member 5, a cylindrical closed space 1 is formed.
1 is provided. Both ends in the axial direction (the left-right direction in FIG. 5) of the closed space 11 are closed by seal rings 12a and 12b, respectively. And inside this closed space 11,
A plurality of inner discs 13 and 13 and outer discs 14 and 14 are alternately arranged in the axial direction (the left-right direction of FIGS. 5 to 6). The inner circular plates 13 and 13 of the two circular plates 13 and 14 have their inner peripheral edges fixed to the outer peripheral surface of the fixing member 3. That is, the fixing member 3
Between the collar portion 15 formed at the base end portion of the inner ring plate 13 and the inner ring plate 13 located on one end side (right end side of FIGS. 5 to 6), between the inner ring plates 13 and 13 adjacent to each other, and the other end. The annular spacers 18, 18 are respectively sandwiched between the inner circular plate 13 located on the side (the left end side in FIGS. 5 and 6) and the fixed plate 17 fitted and fixed to the fixed member 3 above. Then, the fixed plate 17
Is strongly pressed toward the collar portion 15.

On the other hand, a plurality of engaging protrusions 19 and 19 (FIG. 6) are formed on the outer peripheral edges of the outer ring plates 14 and 14, respectively. To
Engagement grooves 20, 20 formed on the inner peripheral surface of the swing member 5
(FIG. 5) is displaceably engaged in the axial direction (left and right direction in FIGS. 5 and 6). As shown in detail in FIG. 7, the thickness T 18 of each spacer 18, ₁₈ is slightly larger than the thickness t 14 of each outer circular plate 14, ₁₄ (T ₁₈
> T ₁₄ ). Therefore, as described above, both the inner and outer circular discs 1
In the state where 3 and 14 are alternately arranged, minute gaps 21 and 21 having a thickness dimension h are formed between the side surfaces of the adjacent circular plates 13 and 14 as shown in FIG. It

As described above, both the inner and outer circular ring plates 13 and 14
The sealed space 11 in which the above are alternately arranged is filled with a viscous liquid such as silicone oil. The filling of this viscous liquid is
The filling is performed through the injection hole 22 formed in the swing member 5, and after the filling, the opening of the injection hole 22 is closed by pushing the steel ball 23.

The automatic tensioner 2 constructed as described above
Elastically presses the pulley 7 toward the belt 1 by the elastic force of the tension spring 24, so that the belt 1 can be irrespective of the dimensional change of the belt 1 and the like due to temperature change and the like and the vibration accompanying the operation of the engine. Keep the tension always constant. Further, the side surfaces of the plurality of inner circular plates 13 and 13 and the side surfaces of the outer circular plates 14 and 14 have minute gaps 21 and 21 respectively.
Viscous liquid exists in the minute gaps 21, 21 facing each other through (FIG. 7). Therefore, the sudden displacement between the two circular plates 13 and 14 is prevented by the shearing force applied to the viscous liquid existing in the minute gaps 21 and 21.
Therefore, even if the tension of the belt 1 partially increases suddenly, the pulley 7 is not immediately displaced. As a result,
Even when the tension of the belt 1 suddenly increases and then sharply decreases when the tension suddenly changes, the looseness of the belt 1 can be prevented.

[0008]

However, in the case of the conventional auto tensioner configured and operating as described above,
During operation, the damper capacity may decrease due to the following reasons. That is, the thermal expansion coefficient of the viscous liquid is
The coefficient of thermal expansion is larger than that of a metal material such as iron or aluminum alloy, which constitutes the fixed member 3 and the swinging member 5, which are members surrounding the. In addition, the temperature of the auto tensioner used in the state of being built in the engine is greatly different between when the engine is stopped and when it is in operation (at atmospheric temperature and 80 to 120 ° C).
Varies between degrees). For example, silicon oil generally used as the viscous liquid has a specific gravity of about 0.975 at 25 ° C., but a specific gravity at 100 ° C. is reduced to about 0.911 (volume: Expands).

Therefore, in order to prevent the pressure in the closed space 11 from rising excessively when the temperature rises and to prevent the viscous liquid from leaking out from the closed space 11, the viscous liquid inside the closed space 11 is prevented. Can not be filled. In other words, in the upper part of the closed space 11 shown in FIG. 8 and FIG.
It is necessary to leave air as shown in. However,
In this way, the air portion 25 left above the closed space 11
(A portion in which the slant lattice is not provided in FIGS. 8 and 9A. The slant lattice portion is a portion in which the viscous liquid exists.) In the swing displacement of the swing member 5 (FIGS. 4 to 5), Outer ring plate 14,
No shearing force acts between 14 and the inner ring plates 13, 13. As a result, it is unavoidable that the damper performance is reduced by the area corresponding to the air portion 25. In particular, under a situation in which the rocking member 5 vibrates reciprocally violently, the air portion 25 is moved to the air portion 25 on the basis of the adhesive force between the viscous liquid and the side surfaces of the both circular plates 13 and 14. As shown in FIG. 3, the circular plates 13 and 14 spread in the circumferential direction. In such a situation, the area where the shearing force acts on the viscous liquid (the area of the slanted grid portion in FIG. 9) further decreases, and the damper performance further deteriorates. As the viscous liquid that can be filled in the damper device of the auto tensioner, there are mineral oil, synthetic oil, and the like in addition to silicone oil. Cause problems. In view of such circumstances, the autotensioner of the present invention has been invented to prevent the deterioration of the damper performance due to the presence of the air portion 25.

[0010]

The autotensioner of the present invention, like the above-mentioned conventional autotensioner, has a fixing member fixed to a fixed portion, a fixing shaft provided on the fixing member, and the fixing member. An oscillating member rotatably supported around the shaft, a pulley rotatably supported by a part of the oscillating member eccentric to the fixed shaft, the fixed part or the fixing member, and A spring for imparting an elastic force to the swinging member in a direction of pressing the pulley toward the belt by locking both ends of the swinging member, a part of an outer peripheral surface of the fixing member, and the swinging member. And a cylindrical hermetically sealed space provided between the inner peripheral surface and a part of the inner circumferential surface, and a plurality of inner circular discs alternately arranged in the inner space of the hermetically sealed space in the axial direction of the fixed shaft. And the outer circular plate and the above enclosed space And a plurality of inner circular discs of which the inner peripheral edge is supported by a part of the outer peripheral surface of the fixed shaft so as not to rotate with respect to the fixed shaft. Each of the circular discs has its outer peripheral edge supported by a part of the inner peripheral surface of the swing member so as not to rotate with respect to the swing member, and has side surfaces of the inner circular disc and the side faces of the outer circular disc that are adjacent to each other. There is a small gap between them.

Particularly, in the autotensioner of the present invention, a compensation space continuous from the upper end of the closed space is provided in a part of the swinging member, and a part of the viscous liquid is contained in the compensating space. The viscous liquid is filled even in the upper end portion of the closed space by allowing it to enter and leave the compensation space.

[0012]

In the autotensioner of the present invention constructed as described above, the swinging member is swung about the fixed shaft by the elastic force of the spring, and the pulley is pressed against the belt to give proper tension to the belt. The action at the time and the action at the time of restraining the belt by limiting the displacement of the swinging member when the tension of the belt suddenly rises are the same as those of the conventional automatic tensioner described above.

In particular, in the case of the autotensioner of the present invention, the viscous liquid is filled up to the upper end of the closed space due to the existence of the compensation space. That is, there is almost no air (or no air) at the portion where the side surfaces of the inner ring plate and the outer ring plate face each other at the upper end of the closed space. Therefore,
Even when a plurality of outer circular discs supported by a part of the inner peripheral surface of the swing member reciprocally swings due to fluctuations in the tension of the belt, the side faces of the plurality of outer circular discs and the fixing member Air does not enter between the side surfaces of the plurality of inner circular plates supported by the outer peripheral surface of a part of. Therefore, the viscous liquid remains between the side surfaces of the two circular plates over their entire surfaces. As a result, a sufficiently large shearing force can be applied between the side surface of the outer ring plate and the side surface of the inner ring plate, and the damper capacity of the auto tensioner can be fully exerted.

[0014]

FIG. 1 shows a first embodiment of the present invention.
A feature of the present invention is that the viscous liquid is filled even in the upper end portion of the closed space by providing the compensation space, and the deterioration of the damper ability when the swing member reciprocally swings is prevented. Since the configuration and operation of the other parts are the same as those of the conventional structure described above, the same parts are designated by the same reference numerals to omit or simplify the overlapping description, and the characteristic parts of the present invention will be mainly described below. .

A circular hole 26 is formed in a part of the oscillating member 5 constituting the automatic tensioner 2a, and a through hole 27 connects the circular hole 26 and the closed space 11. The circular hole 26 is located above the swing member 5 in a state where the auto tensioner 2a is mounted on a fixed portion such as the front surface of the cylinder block. The through hole 27 connects the upper end portion of the closed space 11 and the circular hole 26. In addition, a cylindrical cap 30 having a bottom is oil-tightly fitted into the circular hole 26 to close the opening of the circular hole 26. Therefore, the inside of the circular hole 26 constitutes a compensation space 28a which is shielded from the outside.

When the auto tensioner 2a is installed, the compensation space 28a communicates with the closed space 11 through the through hole 27 in the lower half thereof, and the upper half of the compensation space 28a includes the closed space 11a.
It is located above. In such a compensation space 28a,
A viscous liquid 29 such as silicon oil, which is shown in a slanted lattice in FIG. 1, is stored. The viscous liquid 29 stored in the compensating space 28a in this way passes through the through hole 27 and then the closed space 1
It goes in and out of 1 and compensates the volume change of the viscous liquid 29 accompanying a temperature change. That is, this change in volume is absorbed by a change in the volume of the air layer, which is a compressive fluid, present in the upper half of the compensation space 28a.

Then, the height position of the liquid surface of the viscous liquid 29 stored in the compensation space 28a is regulated near the upper end surface position of the closed space 11 as described above. That is, the sealed space 11 is positioned below the liquid surface except for a part of the large diameter portion near the seal ring 12b. Therefore, inside and outside of both of the closed spaces 11 and both of the circular plates 13 and 14
The viscous liquid 29 reaches the upper end of the part where the
Is full. In addition, the position of the liquid surface is set to the viscous liquid 29.
It is preferable that it exists above the upper end position of the closed space 11 even at the low temperature when the volume of the above is reduced most. However, at the time of use, at least when the temperature rises and the volume of the viscous liquid 29 increases, the viscosity decreases at the same time.
If it exists above the upper end position of 1, it is possible to achieve the object of the present invention that the damper performance during use is secured.

In the case of the autotensioner 2a of the present invention configured as described above, the inner and outer sides of the closed space 11 and the two annular plates 13, due to the existence of the compensation space 28a,
The viscous liquid 29 is filled up to the upper end of the 14 installation portion. That is, at the upper end of this closed space 11, the inner circular disc 1
Air does not exist in the minute gaps 21 and 21 (see FIG. 7) where the side surfaces of the outer ring plates 3 and 13 face each other. Therefore, the pulley 7 reciprocally swings finely based on the tension fluctuation of the belt 1 (see FIG. 4), and a plurality of outer circular discs supported on a part of the inner peripheral surface of the swinging member 5 that is displaced together with the pulley 7. Even when 14 and 14 swing back and forth, the side faces of the plurality of outer circular discs 14 and 14 and the side faces of the inner circular discs 13 and 13 supported by a part of the outer peripheral surface of the fixing member 3 are separated. Air does not enter the minute gaps 21 and 21 between them.

Therefore, in the minute gaps 21 and 21 between the side surfaces of the two circular plates 13 and 14, the entire surfaces of the portions that partition the minute gaps 21 and 21 on the side faces of the circular plates 13 and 14, respectively. Therefore, the viscous liquid 29 remains in the existing state. As a result, a sufficiently large shearing force can be applied between the side surfaces of the inner ring plates 13 and 13 and the side faces of the outer ring plates 14 and 14, and the damper capacity of the auto tensioner 2a is fully exerted. You can let me do it.

Next, FIG. 2 shows a second embodiment of the present invention. In the case of this embodiment, the opening end of the circular hole 26 is closed by the plug 31, and the inside of the circular hole 26 is compensated for by the compensation space 28b.
I am trying. The compensation space 28b is filled with a sponge 32 having closed pores (a large number of pores formed inside are not independently communicating with each other). When the volume of the viscous liquid 29 filled in the auto tensioner 2b increases / decreases with a temperature change, the volume of the sponge 32 expands / contracts to absorb the volume change of the viscous liquid 29. Other configurations and operations are similar to those of the above-described first embodiment.

Next, FIG. 3 shows a third embodiment of the present invention. In the case of the present embodiment, the opening end of the circular hole 26 is closed by a diaphragm 33 made of an elastic material such as rubber, so that the inside of the circular hole 26 serves as a compensation space 28c. When the volume of the viscous liquid 29 filled in the auto tensioner 2c increases / decreases with a temperature change, the diaphragm 33 elastically deforms to absorb the volume change of the viscous liquid 29. Other configurations and operations are similar to those of the above-described first and second embodiments.

The automatic tensioners 2a, 2 of the present invention
In the case of b and 2c, compensation spaces 28a, 28b and 28c
Since the filling operation of the viscous liquid 29 can be performed through, the injection hole 22 and the steel ball 23 which are provided in the conventional structure are unnecessary.
However, it is acceptable to provide the injection hole 22 and the steel ball 23. Further, the pulley 7 is attached to the belt 1 via the swinging member 5.
The spring for giving the elastic force to press is the tension spring 2
4 (not limited to FIG. 4, it is also possible to use a torsion coil spring. In this case, one end of the torsion coil spring is locked to the swing member 5 and the other end is locked to the fixed portion or the fixing member 3. When locking to, the bracket 9 is omitted and instead,
The base end portion (right end portion in FIGS. 1 to 3) of the fixing member 3 is made to project outward in the diametrical direction more than the base end portion of the swinging member 5.

[0023]

Since the autotensioner of the present invention is constructed and operates as described above, a sufficient effective area of the damper device by viscous liquid is secured, sufficient damper performance is maintained, and belt tension fluctuations are maintained. You can surely prevent it.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing the second embodiment.

FIG. 3 is a sectional view showing the third embodiment.

FIG. 4 is a front view showing an installation portion of the auto tensioner.

FIG. 5 is a sectional view showing an example of a conventional structure.

FIG. 6 is an exploded perspective view of the same.

FIG. 7 is an enlarged sectional view of the same portion.

FIG. 8 is a perspective view showing a filling state of a viscous liquid in a closed space in the conventional structure.

9A and 9B are schematic front views showing a state in which an area where a shearing force acts on a viscous liquid changes with rocking motion, FIG. 9A is a stationary state, and FIG. 9B is a rocking motion. Are shown respectively.

[Explanation of symbols]

 1 Belt 2a, 2b, 2c Auto tensioner 3 Fixed member 4 Fixed shaft 5 Swing member 6a, 6b Sliding bearing 7 Pulley 8 Rolling bearing 9 Bracket 10 Engagement part 11 Sealed space 12a, 12b Seal ring 13 Inner ring plate 14 Outside Ring plate 15 Collar portion 16 Bolt 17 Fixing plate 18 Spacer 19 Engaging projection piece 20 Engaging groove 21 Small gap 22 Injection hole 23 Steel ball 24 Pulling spring 25 Air portion 26 Circular hole 27 Through hole 28a, 28b, 28c Compensation space 29 Viscous liquid 30 Cap 31 Plug 32 Sponge 33 Diaphragm

Claims (1)

[Claims] 1. A fixing member fixed to a fixed portion, a fixing shaft provided on the fixing member, a swinging member rotatably supported around the fixing shaft, and one of the swinging members. Part of the pulley is rotatably supported at a portion eccentric to the fixed shaft, and both ends of the pulley are fixed to the fixed portion or the fixing member and the swinging member, so that the swinging member is fixed to the swinging member. A spring that gives an elastic force in a direction of pressing the pulley toward the belt, a cylindrical sealed space provided between a part outer peripheral surface of the fixing member and a part inner peripheral surface of the swinging member, and this sealing A plurality of inner circular plates and an outer circular plate, which are alternately arranged in the axial direction of the fixed shaft, and a plurality of viscous liquids filled in the closed space, Of these, the inner circular plates are the inner peripheral edge of each Part of the outer peripheral surface of the rocking member is supported so as to be unable to rotate with respect to the fixed shaft, and the outer peripheral plates of the plurality of outer circular plates are part of the inner peripheral surface of the swing member.
In the auto tensioner, which is supported so that it cannot rotate with respect to this swing member, and has a minute gap between the side surfaces of the inner ring plate and the outer ring plate that are adjacent to each other,
A compensation space that is continuous from the upper end of the closed space is provided in a part of the swing member, and a part of the viscous liquid is allowed to enter and leave the compensation space, thereby forming an upper end of the closed space. An auto tensioner characterized in that even the part is filled with the above viscous liquid.