JP2000291752A - Belt tension adjusting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make belt tension stably adjustable in a belt tension adjusting device in a transmitting mechanism used in a wide temperature range without deteriorating a function due to a heat shock or causing creep deformation to a synthetic-resin-made sliding bearing. SOLUTION: In this device, a pulley arm 4 is turnably mounted through a synthetic resin-made sliding bearing 3, formed so as to extend a slit linearly in parallel to an axial direction of a cylindrical peripheral wall, in a support point shaft 1 with collar 1a fixed to an engine block of an internal combustion engine for an automobile by a bolt 2, a belt engaging tension pulley is mounted in a rotary shaft in one end of the pulley arm 4, and a piston rod of a damper is brought into contact in a cylinder with the other end of the pulley arm 4. A position around the support point shaft 1 of the pulley arm 4 is adjusted by press elastic force of this tension pulley, so as to obtain a belt tension adjusting device tensing a belt by press contact of the tension pulley with suitable tension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt tension adjusting device for adjusting a belt tension in a power transmission mechanism used in a wide temperature range, such as a timing belt of an internal combustion engine for an automobile and a belt for driving auxiliary equipment. It is.

[0002]

2. Description of the Related Art In general, in order to maintain a constant belt tension for a timing belt for driving a cam of an automobile, a belt for driving auxiliary equipment, and other power transmission mechanisms, to maintain the durability of use of the belt as long as possible. In order to reduce noise during traveling, a belt tension adjusting device as shown in FIGS. 1 and 2 is used.

For example, a belt tension adjusting device for a timing belt for driving a cam of an automobile is provided on a fulcrum shaft 1 with a collar la fixed to an engine block or the like with bolts 2 as shown in FIG. The pulley arm 4 is rotatably mounted via a sliding bearing 26 of the type described above, a tension pulley 7 for engaging with the belt 6 is mounted on the rotating shaft 5 at one end of the pulley arm 4, and the other end of the pulley arm 4 is mounted in a cylinder. A piston rod 9 of a damper 8 having a well-known damper mechanism is brought into contact with the damper 8, and the pulley arm 4 is supported by a pressing elastic force of the piston rod 9;
The belt 6 is slackened by the pressing force of the tension pulley 7, and is tensioned with an appropriate tension.

By the way, a fulcrum shaft 1 of a belt tension adjusting device is used.
The use condition of the sliding bearing 26 that slides on the bearing is that the load fluctuates due to the large surface pressure applied to the sliding surface and the slight amplitude swing acting on the pulley arm 4 from the belt 6.
Further, a moment load acting on the pulley arm 4 due to a change in the tension of the belt 6 is applied to a contact portion between the slide bearing 26 and the fulcrum shaft 1, and these loads act as uneven loads rather than being uniform over the entire contact portion. When the heat of the engine is conducted, the sliding surface becomes high temperature (for example, 150 ° C.),
In addition, various severe conditions such as exposure to low-temperature outside air (for example, −40 ° C.) are operating conditions in which multiple functions are performed.

The sliding bearing 26 used under such severe and special conditions does not cause seizure or wear even when the heat of the engine is conducted and the sliding surface becomes high temperature. The bearing material does not adhere to the fulcrum shaft 1 and heat resistance capable of maintaining mechanical strength even at high temperatures is required.
For this purpose, a resin having heat resistance and self-lubricating properties, for example, a polyimide resin, an unsaturated polyester resin reinforced with a woven fabric, and the like are used.

The conventional slide bearing 26 is formed into a cylindrical shape as shown in FIG. 8, and is fitted into the shaft hole of the pulley arm 4 by press fitting. When such a sliding bearing is fitted into a shaft hole at room temperature, the bearing is press-fitted with an interference so that the bearing does not fall out of the shaft hole even if the bearing contracts in a low temperature state during use.

[0007]

However, in the conventional cylindrical sliding bearing made of synthetic resin as described above, the heat of the internal combustion engine is conducted and the sliding surface is heated to a high temperature state (for example, 150 ° C.). When the resin expands and the outer diameter of the bearing increases, the coefficient of linear expansion of the resin increases at that time.
Since the coefficient of linear expansion is larger than the coefficient of linear expansion of the metal which is the material of the above, the increase in the bearing outer diameter is larger than the increase in the shaft hole diameter of the housing.

Therefore, when a cylindrical sliding bearing made of synthetic resin is tightened with a large force from a metal shaft hole, creep deformation occurs in the outer shape of the sliding bearing. When the heat shock from low to high temperature occurs repeatedly in the use state of the belt tension adjusting device, the outer diameter of the slide bearing gradually decreases, and when used in a low temperature state, the outer diameter of the shaft hole and the outer diameter of the slide bearing is reduced. There is a possibility that a gap may occur between the belt tension adjusting device and the sliding bearing that rotates together with the rotating shaft.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a belt tension adjusting device used in a wide temperature range from a low temperature of about -40 ° C. to a high temperature of about 150 ° C. There is no decrease in function due to repetition, especially the sliding bearing made of synthetic resin does not cause creep deformation, and the fulcrum shaft for swing can be supported stably and rotatably, thereby stabilizing the belt tension. An object of the present invention is to provide a belt tension adjusting device which is adjustable and has high use durability performance.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a pulley arm is rotatably mounted on a fixed fulcrum shaft through a slide bearing, and a tension for belt engagement is attached to one end of the pulley arm. In a belt tension adjusting device in which a pulley is mounted, a piston rod of a damper is brought into contact with the other end of the pulley arm, and the pulley arm is pressed to swing the pulley arm in a belt tension direction, the sliding bearing is made of synthetic resin. And a slit formed in the peripheral wall of the sliding bearing so as to extend in the axial direction.

According to the belt tension adjusting device of the present invention having the above-described configuration, a slit extending in the axial direction is formed on the peripheral wall of the sliding bearing made of a cylindrical molded body, so that the circumferential direction of the heated sliding bearing is improved. Since the thermal expansion of the sliding bearing is freely accommodated by the width of the slit, the thermally expanded sliding bearing is not tightened by a large force from the metal shaft hole, and the outer shape of the sliding bearing is less likely to be creeped.

Therefore, even if a temperature change from a low temperature to a high temperature occurs repeatedly in the use state of the belt tension adjusting device,
No abnormal gap is created between the outer diameter of the slide bearing and the shaft hole, and the fulcrum shaft for swinging is supported with stable rotational torque, and belt tension can be adjusted stably. Become a device.

Further, in the belt tension adjusting device in which the cylindrical molded body is a cylindrical molded body made of a resin composition obtained by mixing a solid lubricant with a thermoplastic polyimide resin, a slide made of a heat-resistant synthetic resin capable of being injection-molded. Since the bearings are mounted, the belt tension adjusting device can respond to demands for cost reduction.

Further, in the belt tension adjusting device in which the tubular molded body is made of an unsaturated polyester resin and an ethylene tetrafluoride resin and reinforced with a woven fabric made of polyethylene terephthalate, heat of the engine is conducted. Therefore, even if the sliding surface of the fulcrum shaft portion is in a high temperature state, seizure does not occur, the resistance when swinging the pulley arm is sufficiently small, and the belt tension adjusting device has a long life with little wear.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The sliding bearing used in the present invention is formed of a synthetic resin cylindrical molded body, and the synthetic resin itself has a required mechanical strength in a wide temperature range from -40 ° C to 150 ° C. Use a synthetic resin that can be used or that can be used in combination with a reinforcing material.

Such synthetic resins include thermoplastic polyimide resin, aromatic polyetherketone resin, polyphenylene sulfide resin, ethylene tetrafluoride resin, P
Fluorinated resin such as FA, FEP, ETFE, EPE,
Heat-resistant resins such as unsaturated polyester resins, vinyl ester resins, copna resins, polybenzimidazole resins, and other engineering plastics, or mixtures or copolymers of heat-resistant resins with other moldable thermoplastics And the like.

Among these, the thermoplastic polyimide resin is obtained by dehydrating and ring-closing a polyamic acid obtained by reacting an ether diamine with one or more tetracarboxylic dianhydrides in an organic solvent. Is commercially available from Mitsui Chemicals, Inc. under the trademark "Auram", and its production method is described in JP-A-61-143478, JP-A-62-68817, and JP-A-62-86021. It is well known.

The ethylene tetrafluoride resin (hereinafter abbreviated as PTFE) may be a powder for molding or a fine powder for a solid lubricant, and it is more preferable to use them in combination. The result is obtained.

Commercially available PTFE is manufactured by Kitamura Corporation:
KTL610, manufactured by Mitsui DuPont Fluorochemicals: Teflon 7J, TLP-10, Asahi Glass: Fluon G1
63, manufactured by Daikin Industries, Ltd .: Polyflon M15, Lubron L5, manufactured by Hoechst, Inc .: Hostaflon TF9205. Further, PTFE modified with alkyl vinyl ether may be used.

In the present invention, the blending amount of the tetrafluoroethylene resin is preferably limited to 3 to 35% by volume. The reason is that if it is less than 3% by volume, the lubricating properties of the resin composition deteriorate, and if it exceeds 35% by volume, the moldability and mechanical properties of the resin composition deteriorate. A preferred compounding ratio is 5 to 30% by volume.

On the other hand, when a resin material having an unsaturated polyester resin or vinyl ester resin as a base material is used as a bearing, it is reinforced with a polyethylene terephthalate woven fabric.
The amount of the polyethylene terephthalate woven fabric contained in the resin composition is preferably 15 to 60% by volume, and 20 to 50% by volume.
Is preferred. If it is less than 15% by volume, the reinforcing effect is not sufficient, and if it exceeds 60% by volume, the moldability is significantly impaired and a satisfactory molded product may not be obtained.

Examples of the solid lubricant compounded in the synthetic resin include graphite in addition to the above-mentioned tetrafluoroethylene resin.

Here, the manufacturing method of the sliding bearing is such that various additives are individually or collectively mixed with the synthetic resin as a main component using a mixer such as a Henschel mixer, a ball mill, a tumbler mixer, and the like. It is supplied to an injection molding machine or a melt extrusion molding machine having good melt mixing properties (for example, a twin screw extruder), or is melt-mixed in advance using a heat roller, a kneader, a Banbury mixer, a melt extruder, etc. I do.

The resin composition can be molded into a sliding bearing by any of extrusion, injection molding and compression molding. However, injection molding is preferable in order to meet demands for mass productivity and cost reduction.

On the other hand, when the woven fabric of polyethylene terephthalate is impregnated with the unsaturated polyester resin and PTFE, the unsaturated polyester resin and the PTFE are impregnated before the impregnation.
It is preferable to mix FE. The mixing method at this time is not particularly limited as long as it is a method of uniformly dispersing. Specific examples of the mixer used include a kneader kneader, a Banbury mixer kneader, and an intermix kneader.

The method for impregnating the above-described polyethylene terephthalate woven fabric with a resin such as an unsaturated polyester resin and molding the same is not particularly limited, and a general FRP production method can be employed. When impregnating the woven fabric with the resin, the woven fabric and the resin may be alternately laminated and compressed,
Alternatively, a prepreg may be manufactured by previously impregnating a woven fabric with a resin, and the prepreg may be laminated. Further, a woven fabric woven in a three-dimensional shape in advance may be impregnated with a resin. Specific examples of such a molding method include a hand lay-up method, a press molding method, a cold press method, an SMC method, a transfer molding method, a resin transfer molding method, a filament winding method, and a pultrusion method.

An embodiment of the present invention will be described with reference to the accompanying drawings. The first embodiment shown in FIGS.
As shown in FIG. 3, one slit extends linearly in parallel with the axial direction of the cylindrical peripheral wall on the fulcrum shaft 1 with the collar la fixed to the engine block of the automobile internal combustion engine. A pulley arm 4 is rotatably mounted via the formed slide bearing 3, a tension pulley 7 for engaging with a belt 6 is mounted on a rotating shaft 5 at one end of the pulley arm 4, and a cylinder is mounted on the other end of the pulley arm 4. A piston rod 9 of a damper 8 having a well-known damper mechanism is brought into contact therewith, the position of the pulley arm 4 around the fulcrum shaft 1 is adjusted by the elastic force of the piston rod 9, and the tension pulley 7 is The belt 6 is pressed against the belt 6 to loosen the belt 6, and the belt 6 is tensioned with an appropriate tension.

The second embodiment is a belt tension adjusting device which employs a sliding bearing 12 made of a cylindrical molded body shown in FIG. 4 instead of the sliding bearing 3 of the first embodiment.
Reference numeral 2 denotes a slit formed on the peripheral wall by inclining the slit 13 extending in the axial direction at an angle of 30 degrees or an arbitrary angle with respect to the axis.

In the second embodiment, the length of the slit 13 can be made longer than that of the first embodiment in accordance with the inclination angle of the slit 13, so that the volume increase of the thermally expanded sliding bearing corresponds to the slit. It is greatly absorbed according to the inclination angle, and creep deformation of the sliding bearing becomes less likely to occur.

The third embodiment is a belt tension adjusting device that employs a slide bearing 14 made of a cylindrical molded body shown in FIG. 5 instead of the slide bearing 3 of the first embodiment.
4 forms a slit 15 extending in the axial direction in the peripheral wall,
Two slits extending from both ends are connected at the center, and a series of slits are formed in a staggered shape so as to have a step-like step.

In the third embodiment, since the slit 15 of the sliding bearing 14 has a part extending in the circumferential direction, the sliding bearing 1
4 can also partially absorb the change due to thermal expansion in the shaft length direction, and the creep deformation of the sliding bearing is less likely to occur.

In the fourth embodiment, a belt tension adjusting device employing a sliding bearing 16 or 19 made of a cylindrical molded body shown in FIG. 6A or 6B instead of the sliding bearing 3 of the first embodiment. The sliding bearing 16 is formed by forming two slits 17 and 18 extending in the axial direction from both ends of the bearing at short intervals, and the sliding bearing 19 extends in the axial direction from both ends of the bearing. Two slits 2
0 and 21 are formed so as to face each other around the axis. As described above, two or more slits may be formed from both ends of the bearing to the middle, and the arrangement of the slits in that case may be arbitrary.

In the fourth embodiment, the sliding bearing 16 or 19
The plurality of slits 17, 18, 20, 21 respectively sufficiently absorb the change due to the thermal expansion of the slide bearings 16, 19, so that the creep deformation of the slide bearing hardly occurs.

In the fifth embodiment, a belt tension adjusting device employing a sliding bearing 22 or 24 made of a cylindrical molded body shown in FIG. 7A or 7B instead of the sliding bearing 3 of the first embodiment. The sliding bearing 22 is formed with a mountain-shaped (or V-shaped) slit 23 crossing the axial direction of the bearing, and the sliding bearing 24 is shaped like a wave (〜) crossing the axial direction of the bearing. The slit 25 is formed.

In the fifth embodiment, the sliding bearing 22 or 24
In addition, since each of the mountain-shaped slits 23 and the corrugated slits 25 are formed, each of the single slits can absorb thermal expansion distortion in the axial direction and the circumferential direction, and is less likely to cause creep deformation of the sliding bearing. is there.

When the slide bearing used in the above embodiment is incorporated in the belt tension adjusting device, one may be used. However, as shown in FIG. 2, two or more sliding bearings are used. A plurality of them may be used in series.

A well-known anti-rotation structure such as a key groove, a knurl groove, an axial vertical groove or the like is used on the inner peripheral surface of the shaft hole of the fulcrum shaft of the pulley arm to prevent the slide bearing from rotating. Is preferred.

[0038]

EXAMPLES AND COMPARATIVE EXAMPLES [Example 1] 86 parts by volume of thermoplastic polyimide resin (AURUM # 450, manufactured by Mitsui Chemicals, Inc.), ethylene tetrafluoride resin (Kitamura Sharp: KTL61)
0) 11 parts by volume and 3 parts by volume of graphite (manufactured by LONZA: graphite powder KS6) were sufficiently mixed using a Henschel mixer, and then supplied to a twin-screw extruder. The cylinder temperature was 410 ° C and the screw rotation speed was 100 rpm.
To produce pellets. The resulting pellet is
Injection molding was performed to form a slit having a shape of FIG. 4 and a width of 2 mm at an inclination angle of 30 degrees with respect to the axis.
A cylindrical molded body (test piece of a sliding bearing) having an inner diameter of 18.1 mm and a length of 20 mm was obtained.

The obtained test piece was subjected to a durability test by the following thermal shock cycle, and the results are shown in Table 1.

<Durability Test> A cylindrical housing made of an aluminum alloy (ADC12) having an outer diameter of 30 mm, an inner diameter of 21 mm, and a length of 50 mm was formed as a cylindrical housing assuming a shaft hole into which a test piece of a sliding bearing was press-fitted. A bearing test piece with a reduced shaft diameter is placed in this cylindrical housing at room temperature (23 ° C.).
After a 1-hour press in the oven in an atmosphere of 150 ° C., a heat shock cycle of rapidly returning to room temperature after being exposed to a freezing atmosphere of −40 ° C. for 1 hour, and performing 10 units continuously, The state of the sliding bearing test piece in the housing immediately after the test was observed.

In the evaluation, there was no looseness and no abnormality in the slide bearing test piece (marked with 〇), there was looseness (marked with △), it was loosened until it fell off the housing, and creep deformation was progressing (marked with “x”). And the results are shown in Table 1.

[0042]

[Table 1]

Example 2 A pellet of the same material as in Example 1 was injection-molded to form a slit having a shape of FIG. 3 and a width of 2 mm parallel to the axis, and an outer diameter of 21.3 mm and an inner diameter of 18.1.
A cylindrical molded body (a test piece of a sliding bearing) having a length of 20 mm and a length of 20 mm was obtained.

The obtained test pieces were subjected to the above-mentioned durability test, and the results are shown in Table 1.

Example 3 Vinyl ester resin (Mitsui Chemicals: Esther H8100, 1% methyl ethyl ketone peroxide, 0.3% cobalt naphthenate) 6
5 volume parts, ethylene tetrafluoride resin (Kitamura Co., Ltd .: KTL
610) 10 parts by volume are sufficiently mixed using a mixer, and a polyethylene terephthalate woven fabric (plain weave; warp; 30/2 cotton count; weft; 20/2 cotton count; density (warp × weft; (Number / inch); 52 × 40)
Was impregnated with 35 parts by volume of woven fabric, and then laminated on a cylindrical mandrel to form a cylindrical laminated body. The cured cylindrical laminated body was cut to produce a cylindrical molded body (a test piece of a sliding bearing) having the same shape (same dimensions) as in Example 1 and having an axial slit.

The obtained test pieces were subjected to the durability test described above, and the results are shown in Table 1.

Comparative Example 1 Pellets of the same material as in Example 1 were injection-molded into a shape shown in FIG. 8 (a cylinder without slits).
21.3mm outside diameter, 18.1mm inside diameter, 20mm length
(A test piece of a sliding bearing) was obtained.

The obtained test piece was subjected to the durability test described above, and the results are shown in Table 1.

[Comparative Example 2] A cylindrical laminate made of the same material as in Example 3 was cut and formed into an outer diameter of 21.3 mm, an inner diameter of 18.1 mm and a length of 20 in the shape shown in FIG.
mm was obtained as a cylindrical molded body (a test piece for a sliding bearing).

The test pieces thus obtained were subjected to the above-mentioned durability test, and the results are shown in Table 1.

As is clear from the results shown in Table 1, even in Comparative Example 1 using a sliding bearing formed of a polyimide resin having excellent heat resistance, the sliding bearing test piece undergoes creep deformation due to heat shock. Looseness to the housing has occurred. Further, the sliding bearing formed of a vinyl ester resin, even when reinforced with a woven fabric, caused creep deformation due to heat shock, and was loosened until it fell off the housing.

On the other hand, the slide bearing test pieces of Examples 1 to 3 in which the slits of a predetermined shape were formed did not undergo creep deformation due to heat shock and did not loosen the housing.

[0053]

As described above, according to the present invention, the sliding bearing of the fulcrum shaft of the pulley arm is formed of a synthetic resin sliding bearing having a predetermined slit to form a belt tension adjusting device. Even when used in a wide temperature range from a low temperature to a high temperature of about 150 ° C, the function does not decrease due to repeated heat shock, and especially the sliding bearing made of synthetic resin does not cause creep deformation, and the fulcrum shaft for swinging Can be stably rotatably supported, so that the belt tension can be stably adjusted, and there is an advantage that the belt tension adjusting device has high use durability performance.

[Brief description of the drawings]

FIG. 1 is a front view showing an outer shape of a belt tension adjusting device.

FIG. 2 is a partially cut-away side sectional view of a fulcrum shaft illustrating a mounting state of a slide bearing.

FIG. 3 is a perspective view of a slide bearing used in the first embodiment.

FIG. 4 is a perspective view of a slide bearing used in a second embodiment.

FIG. 5 is a perspective view of a slide bearing used in a third embodiment.

FIG. 6 is a perspective view of a slide bearing used in a fourth embodiment.

FIG. 7 is a perspective view of a slide bearing used in a fifth embodiment.

FIG. 8 is a perspective view of a slide bearing used in a conventional belt tension adjusting device.

[Explanation of symbols]

1 fulcrum shaft 2 bolt 3 sliding bearing 4 pulley arm 5 rotating shaft 6 belt 7 tension pulley 8 damper 9 piston rod 10, 12, 14, 16, 19, 22, 24, 26 sliding bearing 11, 13, 15, 17, 18, 20, 21, 23, 2,
5 slit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Masuzou Ito, 970, Ota, Aza, Toin-cho, Inaba-gun, Mie Prefecture (72) Inventor, Masahiko Mizutani 1578, Higashikaizuka, Iwata-shi, Shizuoka, Japan F term (reference) 3J049 AA01 AB05 BA05 BB01 BB11 BB21 BB25 BD01 BH01 BH02 CA02 CA03

Claims (4)

[Claims] A pulley arm is rotatably mounted on a fixed fulcrum shaft via a sliding bearing, a tension pulley for belt engagement is mounted on one end of the pulley arm, and a piston rod of a damper is applied to the other end of the pulley arm. A belt tension adjusting device for causing the pulley arm to swing in the belt tension direction by pressing the piston rod, wherein the slide bearing is formed of a synthetic resin tubular molded body, and is axially attached to a peripheral wall of the slide bearing. A belt tension adjusting device, wherein an extending slit is formed. 2. The belt tension adjusting device according to claim 1, wherein the cylindrical molded body is a cylindrical molded body made of a resin composition obtained by mixing a solid lubricant with a thermoplastic polyimide resin. 3. The belt tension adjusting device according to claim 1, wherein the cylindrical molded body is a cylindrical molded body made of an unsaturated polyester resin and an ethylene tetrafluoride resin and reinforced with a woven fabric made of polyethylene terephthalate. 4. The belt tension adjusting device according to claim 1, wherein the belt is a belt for a power transmission mechanism disposed adjacent to an internal combustion engine for a vehicle.