JPH0989152A - Sleeve for wax sealed thermo valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a needle to be smoothly slid and operated also under the condition that heating and cooling are repeated, by making a sleeve for a wax sealed thermo valve have excellent sealing performance by elasticity proper to rubber, have the long life, and exhibit stable low friction characteristics and low abrasion characteristics. SOLUTION: A thermally-sensitive chamber 2 provided in a valve and in which wax 1 is filled is hermetically sealed by a rubber sleeve 4 through which a needle 3 is inserted. The slide-contact surface of the sleeve 4, in relation to the needle 3, to be used for a wax sealed thermo valve for opening and closing a valve 5 by projecting and retreating the needle 3 to and from the sleeve 4 according to the thermally-sensed temperature is formed of a lubricative rubber component including tetra-fluoroethylene resin powder of 10 to 100 parts weight in which a carbon material projects on the front surface and nodular graphite of 5 to 80 parts weight in relation to rubber of 100 parts weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sleeve mounted on a wax-sealed thermovalve for adjusting the flow rate of fluid according to temperature.

[0002]

2. Description of the Related Art Generally, in a water-cooled engine, in order to prevent overheating or overcooling, the amount of water flowing to a radiator is automatically adjusted according to the water temperature. Especially, in a gasoline engine, water or an antifreeze solution in the radiator is adjusted. A wax-filled thermo valve is used to adjust the degree of opening and closing of a choke valve that adjusts the amount of gasoline supplied according to the temperature.

The structure and operation of such a wax-filled type thermo-valve will be described with reference to FIGS. 1 and 2. In this case, a thermosensitive chamber 2 having a cylindrical shape filled with wax 1 is provided in the valve. The downward opening of the chamber 2 is sealed by a sleeve 4 into which a needle 3 is slidably inserted, and the needle 3 is slidably moved in and out of the sleeve 4 in accordance with a heat-sensitive temperature, whereby a valve (valve body) 5 is opened. It opens and closes.

For example, in a thermo-valve, the wax 1 having a predetermined melting point enclosed in the needle 3 and the heat-sensitive chamber 2 is 70 ° C.
When heated to the vicinity, the wax 1 undergoes a phase change from solid to liquid and its volume expands rapidly.
The internal pressure increases, and the relative position of the heat-sensitive chamber 2 rises due to the reaction force that pushes out the needle 3, the valve 5 moves away from the valve seat 6, and the flow path 7 opens.

In this way, the thermovalve opens the flow passage when the liquid temperature rises and closes the flow passage when the liquid temperature falls, but in those cases, the sleeve 4 and the needle 3 slide.

[0006] In order that the needle 3 and the sleeve 4 as described above slide smoothly and have a reliable sealing property,
Grease is applied to these sliding surfaces.

[0007]

However, the conventional wax-enclosed thermovalve sleeve described above has a drawback in that the applied lubricant is washed away with the lapse of use time and the frictional resistance with the needle increases. .

Further, when the needle or the sleeve is incorporated in the heat-sensitive chamber, foreign matter or air is easily mixed in the sliding surface, and the stick-slip phenomenon that the movement of the needle does not move smoothly occurs easily. It is expected that it will not operate correctly.

Particularly, in the valve for adjusting the gasoline supply amount, there is a phenomenon that the rubber sleeve contracts in an extremely cold place and clings (sticks) to the needle, and even in this case, there is a drawback that delicate control cannot be performed. .

In addition, the following various measures have been studied so far as measures for generally reducing the friction of rubber materials and increasing wear resistance, but none of them have been effective.

That is, in the method of adhering a tetrafluoroethylene resin sheet on the rubber surface (Japanese Patent Publication No. 46-23681), when the shaft for mounting the seal is relatively small,
The tetrafluoroethylene resin sheet is easily peeled off and has no durability, and the manufacturing process for attaching the sheet is complicated and the cost increases.

A seal made of an oil-containing rubber obtained by impregnating a diene rubber material with a lubricating oil has a mechanical strength of a molded article extremely lowered, and its slidability is lowered with time and is unstable.

A rubber material coated with a tetrafluoroethylene resin on the surface cannot be obtained with good abrasion resistance because the rubber deteriorates when the coating film of the tetrafluoroethylene resin is fired. Further, since such a coating film does not have sufficient followability to the deformation of rubber,
There is a problem that the coating film is peeled off due to stretching deformation when attaching the seal.

Further, a seal employing a method in which the surface of a rubber material is treated with a chlorine-based solvent for smoothing or plasma treatment is not satisfactory in slidability.

Furthermore, when a seal is formed from a composition containing a diene rubber, silicone rubber or fluororubber as a main component and a solid lubricant of tetrafluoroethylene resin (Teflon) or silicone, the seal is slightly formed. Although it is possible to reduce the friction coefficient of the above, such molded products have high hardness and poor sealability, or such solid lubricants have poor wettability with the main component rubber, so tear strength is There were problems such as extremely reduced wear resistance and poor wear resistance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a wax-enclosed thermovalve sleeve with excellent sealability due to elasticity peculiar to rubber, and long life and stable low friction characteristics. And, as a material exhibiting low wear characteristics, the needle can be smoothly slid even under the condition that heating and cooling are repeated.

[0017]

In order to solve the above-mentioned problems, in the present invention, a wax-filled heat-sensitive chamber provided in a valve is sealed with a rubber sleeve having a needle inserted therethrough, and the temperature is adjusted according to the heat-sensitive temperature. In the sleeve used in a wax-sealed thermovalve that opens and closes the valve by sliding the needle in and out of the sleeve, the sliding contact surface of the sleeve with the needle is 100 parts by weight of acrylonitrile-butadiene rubber. Tetrafluoroethylene resin powder 10 to 100 parts by weight, spherical graphite 5 to
It was formed of a lubricating rubber composition containing 80 parts by weight.

Further, as the tetrafluoroethylene resin powder, a tetrafluoroethylene resin powder is used which is co-precipitated with a carbon material after the completion of emulsion polymerization so that the carbon material is projected on the surface.

Alternatively, as the tetrafluoroethylene resin powder, a tetrafluoroethylene resin powder in which a tetrafluoroethylene resin and a carbon material are dry-mixed and a carbon material is projected on the surface is adopted.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylonitrile butadiene rubber (hereinafter abbreviated as NBR) according to the present invention may be any one having a rubber-like elasticity at room temperature, and a wide range of compounds synthesized by a known synthesis method can be used. Can be adopted.

That is, since NBR is a copolymer of butadiene and acrylonitrile, its physical properties can be changed by adjusting the amount of acrylonitrile within the range of about 15 to 50%. The amount of such nitrile can be classified into, for example, less than 24% of low nitrile, 24 to 30% of medium nitrile, 30 to 36% of medium high nitrile, 36 to 42% of high nitrile, and 42% of extremely high nitrile. In order to increase the wear resistance, aging resistance, and tensile strength of rubber in such a range, it is preferable to increase the amount of nitrile, but rubber elasticity, cold resistance, and low temperature characteristics are not impaired. Nitrile content in the range of about 24% to 42%, or about 2
It is preferably in the range of more than 4% and less than 42%.

The molecular weight of such NBR is usually preferably 50,000 or more, and one having a high molecular weight as much as possible gives good results. Therefore, it is more preferably 70,000 or more, particularly preferably 10 to 50. Adopt about 10,000 items. The following are commercially available NBRs that satisfy the required conditions. Nippon Synthetic Rubber Co., Ltd .: JSR-N Nippon Zeon Co., Ltd .: NIPOL Goodyear Co., Ltd .: CHEMIGUM.

Further, the tetrafluoroethylene resin (hereinafter abbreviated as PTFE) powder in the present invention means
Molding powder produced by suspension polymerization method,
Although any of the fine powders produced by the emulsion polymerization method may be used, after being subjected to pressure / heat treatment, pulverization or pulverization, γ-ray irradiation treatment or electron beam irradiation treatment, or γ after polymerization It is possible to use those having an average particle size of 20 μm or less that has been subjected to a ray irradiation treatment or an electron beam irradiation treatment. Examples of commercially available products include the following. Daikin Industries, Ltd .: Lubron L10 Asahi Glass: Fluon G163, Fluon CD1, Lubricant L169, L182J, Mitsui DuPont Fluorochemicals: Teflon 7J.

Furthermore, as a more preferable PTFE powder, as shown in the enlarged view of FIG. 3, a carbon material 12 such as scaly graphite is projected on the surface of the PTFE powder 11, that is, carbon. Material 12 to PTF
It is a state in which the surface of the E powder 11 is pierced.

To produce such PTFE powder,
For example, at the end of emulsion polymerization in the production of fine powder, it is coprecipitated with a carbon material for coagulation, washed, and then dried.
As another manufacturing method, the carbon material may be dry mixed with the PTFE powder, and the PTFE material may be pierced on the surface of the PTFE powder.

As the carbon material, powdered products having various crystal states from general carbon powder to graphite can be adopted.
Since it is expected that the crystal structure due to graphitization will improve the lubricity, it is particularly preferable to use graphite. Further, it may be HAF, SAF, FEF, MT, or the like, which is a carbon black having a large structure, which is generally used as a rubber material.

In the PTFE powder 11 as described above, the carbon material 12 made of graphite or the like is projected in all directions (radially) on the surface of the powder as shown in the figure.
Since the rubber base material 13 and the carbon material 12 have a good physical pile effect and are reliably retained, and the affinity between the rubber base material 13 and the carbon material 12 is good, the composition obtained by kneading the rubber base material 13 and the PTFE powder 11 retains the carbon material. A rubber composition having a higher strength than that of a rubber composition containing PTFE powder is obtained.

The spheroidal graphite used in the present invention means spheroidal graphite produced as a by-product in the step of spinning from the pitch, or phenolic resin reacted with paraformaldehyde under a catalyst to polymerize into spheres, and , Spherical graphite that has been fired and crushed. Examples of commercially available spherical graphite include the following. Osaka Gas Chemicals Co., Ltd .: Mesocarbon beads Kanebo Co., Ltd .: Bell Pearl, Unitika Co., Ltd .: Univex, Nippon Carbon Co., Ltd .: Micro carbon beads.

In the present invention, the blending weight ratio of NBR and PTFE powder is such that PTF is added to 100 parts by weight of NBR.
The E powder is preferably 10 to 100 parts by weight. PT
If the FE powder is less than 10 parts by weight, sufficient frictional properties cannot be imparted to the NBR, and if it is blended in a large amount in excess of 100 parts by weight, the rubber hardness becomes high and the elastic properties disappear, or the mechanical strength extremely decreases. It will not be practically applicable.

The blending weight ratio of the spherical graphite used in the present invention is 5 to 80 parts by weight with respect to 100 parts by weight of NBR. The reason for this is that if the compounding ratio is less than 5 parts by weight, NB
A rubber composition which cannot impart sufficient wear resistance to R and is compounded in a large amount in excess of 80 parts by weight to increase rubber hardness and lose elastic properties, or to have mechanical strength extremely deteriorated, which cannot be practically used. Because it becomes a thing.

In the present invention, a known compounding agent for rubber or a known additive may be compounded in an amount that does not impair the purpose.

(1) Reinforcing agent: carbon black, silica, clay, calcium carbonate, magnesium hydroxide, aluminum hydroxide, aluminum oxide, talc, mica, kaolin, bentonite, shirasu, wollastonite, silicon carbide, glass powder, Carbon powder, boron fiber, aramid fiber, etc. (2) Vulcanization aid: zinc white, fatty acid, etc. (3) Vulcanization accelerator: guanidines, sulfur, aldehyde-amines, zinc, etc. (4) Plasticizer: dimethyl phthalate, dioctyl phthalate, etc. (5) Anti-aging agent: amines, phenols, etc. (6) Others, antioxidants, ultraviolet absorbers, flame retardants, colorants, etc.

Further, in order to improve releasability at the time of molding and non-tackiness of the surface, oil, wax or grease may be added. The blending amount is such that it does not affect the mechanical strength of the rubber molded product, that is, NBR.
The amount is preferably 2 to 20 parts by weight, more preferably 5 to 10 parts by weight, based on 100 parts by weight.

As a solid lubricant, in addition to PTFE, tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), which is a molten fluororesin, and tetrafluoroethylene-hexafluoropropylene. You may add a copolymer (FEP) etc.

The method of mixing the various raw materials described above is not particularly limited, and is a method that is generally widely used, for example, NBR as the main raw material and other fillers are individually and sequentially mixed or collectively roll-mixed. Machine, propeller mixer,
Mixing may be performed with a kneader mixer or other mixer. In addition,
At this time, it is desirable to provide a temperature controller to prevent heat generation due to friction. Further, when a roll mixer is used, it is preferable to carry out thin threading with a roll interval of 3 mm or less for finish mixing.

The sleeve according to the present invention does not require a particularly limited means in the molding step, and is temporarily vulcanized (for example, 140 to 140) by an ordinary press molding method.
170 ° C for 10 to 30 minutes, pressurization 50 to 150 kgf / c
m ² ), and then secondary vulcanization (for example, at 150 to 180 ° C. for 2 to 20 hours without pressure), and molding can be performed.

It is sufficient for the sleeve molded product that the sliding contact surface with the needle is formed of the lubricating rubber composition. For that purpose, the sleeve may be integrally molded of the above-mentioned lubricating rubber composition. However, it may be a composite molded article with a metal material or another polymer material. In particular, a polymer material having a small heat transfer coefficient is preferable because a heat insulating action occurs at a key portion in the valve. In addition, if the sleeve has a well-known lip structure such as that used in V-rings on the inner peripheral surface of the sleeve, it can be expected to prevent the grease applied to the inner peripheral surface from being discharged, or the strength of the molded product is improved. Is preferable.

[0038]

EXAMPLES The raw materials used in Examples and Comparative Examples are summarized below. The blending ratio of each component is shown in parts by weight based on 100 parts by weight of the following NBR basic blending.

[NBR basic composition A] (high nitrile type, nitrile amount 36 to 42%): Japan Synthetic Rubber Co., Ltd .: JSR220S 100 parts by weight Sodium stearate: General industrial material 1 〃 Carbon black: FEF 30 〃 Vulcanization accelerator 1: Ouchi Shinko Chemical Industry Co., Ltd .: TT 2 vulcanization accelerator 2: Ouchi Shinko Chemical Industry Co., Ltd .: M 2 〃 Vulcanization aid: Zinc oxide (activated zinc white) 10 〃 Vulcanizing agent: Sulfur 1 0.0 〃 [NBR basic compounding B] (Medium nitrile type, nitrile amount 25-30%) Made by Japan Synthetic Rubber Co., Ltd .: JSR240S 100 parts by weight Sodium stearate: General industrial material 1 〃 Carbon black: FEF 30 〃 Vulcanization accelerator 1: Ouchi Shinko Chemical Co., Ltd .: TT 2 〃 Vulcanization accelerator 2: Ouchi Shinko Chemical Co., Ltd .: M 2 〃 Vulcanization aid: Zinc oxide (active zinc white) 10 〃 Vulcanization : Sulfur 1.0 〃 [lubricant] (1) graphite coprecipitation PTFE [PTFE-1] Graphite having an average particle size of 6μm after completion of polymerization by emulsion polymerization and 7:
It was obtained by coprecipitation in a weight ratio of 3, coagulation and washing. (2) Dry blend PTFE with graphite [PTFE-
2] PTFE (Lubricant L182J) manufactured by Asahi Glass Co., Ltd. was dry blended with graphite having an average particle size of 6 μm in a Henschel mixer at a weight ratio of 7: 3. (3) PTFE [PTFE-3] Asahi Glass Co., Ltd .: PTFE Lubricant L182J (4) ETFE (Asahi Glass Co., Ltd .: Aflon COP Z88
20) (5) Spherical graphite (Bellpearl C2000 manufactured by Kanebo) (6) Silicone oil (KF9 manufactured by Shin-Etsu Silicone)
6-300).

[Examples 1 to 9 and Comparative Examples 1 to 5] NBR was applied to a roll mixer adjusted to a roll interval of about 5 to 10 mm.
(220S or 240S) is wound, inorganic filler, antioxidant, carbon, sulfur and vulcanization accelerator are sequentially mixed in the proportions shown in the basic composition A or B, and finally the proportions shown in Table 1 or Table 2. And kneaded PTFE and other fillers.

After that, the roll interval was adjusted to 1 mm and thin threading was performed 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 ° C or lower. Next, the cooling water was stopped, steam was passed through the roll to adjust the rubber temperature to 70 ° C or higher and 90 ° C or lower, and then the roll interval was narrowed to 1 mm, and thin threading was performed 10 times, and 10 kg of compound was used for each. Obtained.

The compound obtained as described above was press-molded with a mold having a length of 300 mm, a width of 300 mm and a thickness of 1 mm, and primary vulcanization (160 ° C., 10 minutes, press pressure: 12).
0 kgf / cm ² ) and secondary vulcanization (free heating, 15
0 ° C., 4 hours). The dynamic friction coefficient, wear coefficient, and mechanical properties (surface hardness, tensile strength, elongation rate) of each sheet-shaped test piece that had been vulcanized in this manner were determined.

Further, a test piece of a sleeve having the shape shown in FIGS. 1 and 2 was separately manufactured by the same method, and an actual machine test was conducted on this test piece. Each test method is as follows.

(A) Friction / wear test: inner diameter φ17 mm,
A ring-shaped sheet test piece with an outer diameter of φ21 mm is φ17 x φ2
A friction test piece was adhered to a 1 × t10 (mm) aluminum alloy ring. The mating material was a polished product of bearing steel (SUJ2), and evaluated by a thrust type friction tester. The test conditions were a peripheral speed of 1.0 m / min, a surface pressure of 3.0 kgf / cm ² , and a test time of 100 hours, at the beginning of the test (indicated by int in the table) and thereafter (after 50 hours and 100 hours). Dynamic friction coefficient and wear coefficient (× 10 ^-10 cm ³ / kgf ・ m)
Is also shown in Table 3 or Table 4.

(B) Mechanical Properties The obtained sheet-shaped test piece was measured according to JIS-K6301 in hardness (JIS-A) and tensile strength (kgf / c).
m ² ) and elongation (%) were examined, and the results are also shown in Table 3 or Table 4.

(C) Actual machine test: (heat-sensitive operability of sleeve and wear resistance of sliding surface) A sleeve test piece was attached to the wax-sealed thermo-valve described in FIGS. 1 and 2, and a flow path of this valve was attached. 1 heating / cooling cycle of passing antifreeze liquid for radiator from -30 ° C to 70 ° C at a heating / cooling rate of 5 ° C / min.
000 cycles were performed. At the beginning of the test, the heat-sensitive operability of the sleeve after 500 cycles and 1000 cycles was examined, and the wear resistance of the sliding surface after 1000 cycles was examined.

The heat-sensitive operability of the sleeve was evaluated in the case where the movement amount (distance) of the sleeve with respect to the needle exhibits the behavior of FIG. 4A (good), and in the case of the behavior of FIG. 4B. The results are also shown in Table 3 or Table 4 as defective (marked with X).

The wear resistance of the sliding surface of the sleeve was evaluated after 1000 cycles by examining the presence or absence of wear on the sliding surface of the inner diameter of the sleeve. . In this test, a small amount of the same general purpose grease was applied to the surface of the needle.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

[Comparative Example 6] In the same manner as in Comparative Example 1, NB
A compound of R basic formulation B was prepared and a test piece was obtained by the same production method as in Comparative Example 1. Commercially available coating agent for rubber on this test piece (Emullon 345, manufactured by Nippon Acheson Co., Ltd.)
Was formed into a film of about 15 μm by a spray coating method. After coating, it was dried in an electric furnace at 80 ° C. for 1 hour and further baked to finally complete a test piece.

The obtained test pieces were evaluated by the same test method as in the Examples, and the results are shown in Table 4 together.

As is clear from the results in Tables 3 and 4, Comparative Example 1 containing only the general NBR compound had a high friction coefficient and a large amount of wear. In addition, NBR with PTFE
In both Nos. 2 and 3 in which the rubber composition was added, the friction coefficient was slightly lower than that of the rubber base material, but the abrasion coefficient was not sufficiently improved. In Comparative Example 4 containing spheroidal graphite, the wear resistance was slightly improved, but the friction coefficient was large, and the friction torque was extremely increased in the actual machine test. In Comparative Example 5 containing the silicone oil, the mechanical strength (tensile strength) was remarkably lowered, and the wear characteristics were also extremely poor accordingly. In each of the comparative examples, in the actual machine test, the heat-sensitive operability of the sleeve was not sensitive and its behavior was poor, and a wear mark was confirmed on the inner peripheral surface of the sleeve.

However, Examples 1 to 9 in which the powdery PTFE having the carbon material protruding on the surface and the spherical graphite were added together
Has a small decrease in mechanical strength, a low coefficient of friction and excellent wear resistance, and the heat-sensitive operability of the sleeve is sensitive and its behavior is good even in actual machine tests. There was no

[0057]

As described above, according to the present invention, the sliding surface of the wax-enclosed thermovalve sleeve with respect to the needle is made of acrylonitrile-butadiene rubber and tetrafluoroethylene resin powder having a carbon material projected on the surface. Since it is made of a lubricating rubber composition containing a predetermined amount of spherical graphite, this sleeve has excellent sealability due to the elasticity peculiar to rubber, and exhibits long life and stable low friction and wear characteristics. The advantage is that the needle can be smoothly slid under the condition of repeated heating and cooling.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating the operation of a wax-sealed thermovalve in a high temperature state.

FIG. 2 is a sectional view for explaining the operation of the wax-sealed thermovalve in a low temperature state.

FIG. 3 is a schematic diagram showing a tetrafluoroethylene resin powder in a rubber base material.

FIG. 4A is a diagram showing a relative relationship (good behavior) between the movement amount and temperature of the sleeve of the wax-filled type thermovalve. (B) A relative relationship between the movement amount of the sleeve and temperature of the wax-filled type thermovalve (defective). Chart showing various behaviors

[Explanation of symbols]

 1 Wax 2 Heat Sensitive Chamber 3 Needle 4 Sleeve 5 Valve 6 Valve Seat 7 Flow Path 11 PTFE Powder 12 Carbon Material 13 Rubber Base Material

Claims (3)

[Claims] 1. A wax-filled thermosensitive chamber provided in a valve is sealed with a rubber sleeve having a needle inserted therein, and the valve is opened and closed by sliding the needle in and out of the sleeve according to a thermosensitive temperature. In the sleeve used for the wax-filled type thermovalve, the sliding contact surface of the sleeve with the needle is 10 to 100 parts by weight of tetrafluoroethylene resin powder and 5 to 80 parts by weight of spherical graphite based on 100 parts by weight of acrylonitrile butadiene rubber. A wax-enclosed thermovalve sleeve, characterized in that it is formed of a lubricious rubber composition containing parts. 2. The wax-filled thermovalve according to claim 1, wherein the tetrafluoroethylene resin powder is a tetrafluoroethylene resin powder which is co-precipitated with a carbon material after completion of emulsion polymerization so that the carbon material is projected on the surface. sleeve. 3. The wax-filled thermovalve according to claim 1, wherein the tetrafluoroethylene resin powder is a tetrafluoroethylene resin powder obtained by dry-mixing a tetrafluoroethylene resin and a carbon material to project a carbon material on the surface. Sleeve.