JP4589154B2 - Seal ring - Google Patents

Description

  The present invention relates to a seal ring for an automatic transmission (hereinafter referred to as “AT”) of an automobile, and more particularly to an automatic transmission that is in sliding contact with a rotating shaft made of a die-cast aluminum alloy (hereinafter referred to as “aluminum alloy”). The present invention relates to a rotary shaft seal ring that seals oil (Automatic Transmission Fluid, hereinafter referred to as “ATF”).

  For the purpose of improving the fuel efficiency of automobiles, various attempts have been made, such as miniaturization and thinning of automobile parts or the use of light metals such as aluminum. Even in ATs, aluminum alloys are often used for the rotating shaft and housing, and continuously variable transmission with good fuel efficiency can be mounted not only on conventional high-end large vehicles but also on general small vehicles. Accordingly, there is a demand for a small-diameter seal ring that can handle soft light metals such as aluminum alloys. Conventional rotary shafts and housings of iron-based materials have conveniently used cast iron or particularly polytetrafluoroethylene (hereinafter referred to as “PTFE”) as a seal ring material. In particular, PTFE has demonstrated excellent performance. However, the PTFE also has a problem that against the aluminum alloy rotating shaft, the opponent's aggression becomes stronger under high temperature and high speed sliding conditions, and both the PTFE seal ring and the aluminum alloy rotating shaft cause abnormal wear. did. The friction mechanism when PTFE slides against the mating metal is said to be that the PTFE that was first worn moves to the mating metal surface and slides between the PTFE, reducing the friction coefficient and reducing the amount of wear. Yes. When the mating metal is an iron-based material, PTFE can be transferred and fixed smoothly to the mating metal surface. Under sliding conditions, aluminum adhesion occurs, causing abnormal wear as described above.

  The PTFE problem for aluminum alloy rotating shafts can be addressed by using a typical polyetheretherketone resin (hereinafter referred to as “PEEK”) as a high temperature engineering polymer instead of PTFE. ing. PEEK has about four times the tensile strength and hardness compared to PTFE, but has a tensile elongation of 1/10 or less and lacks flexibility, but has the property that aluminum does not easily adhere. As resins having similar properties to aluminum alloys, polyetherketon (hereinafter referred to as “PEK”), polyethernitrile (hereinafter referred to as “PEN”), polyphenylenesulfide (hereinafter referred to as “PPS”). Said).

  In general, PTFE and PEEK alone do not satisfy the required performance as a seal ring for AT, so wear resistance, elastic modulus, creep resistance, heat resistance, pressure resistance, thermal conductivity, oil resistance, lubricity, moldability, etc. In order to satisfy the required performance, it is generally used in combination. Specifically, in order to improve mechanical properties and wear resistance, fibrous fillers such as glass fibers, carbon fibers, and potassium titanate whiskers, or scaly fillers such as graphite, mica, and talc are added. In order to impart low friction properties, solid lubricants such as PTFE, graphite and molybdenum disulfide are added. Regarding PEEK materials, carbon fiber, PTFE, talc, or calcium carbonate is combined with PEEK (Japanese Patent Laid-Open No. 5-262976: Patent Document 1), carbon fiber, PTFE, granular or whisker shape with Mohs hardness of 3 or less A combination of magnesium sulfate or calcium sulfate (Japanese Patent Laid-Open No. 2001-49111: Patent Document 2) has been proposed.

  In addition, PEEK is extremely expensive, and it is a fact that the market has not yet reached a satisfactory situation in terms of cost, and there is a demand for satisfying the required performance by using as few PEEK as possible. However, since the brittleness increases by adding a large amount of filler, when the seal ring is expanded and attached to the shaft, the joint is allowed, especially for small seal rings with an outer diameter of 30 mm or less. Problems such as breakage exceeding the amount of elastic deformation occur.

  As a method for improving brittleness, it is known that flexibility is imparted by blending an elastomer with a PPS resin (Japanese Patent Laid-Open No. 5-239350: Patent Document 3). However, when an elastomer having low heat resistance is added to a resin molded at a high temperature such as PEEK, there are problems such as a decrease in heat resistance and gas generation during molding.

  In addition, there is a composite filler without agglomerates obtained by uniformly mixing and grinding calcium carbonate, which is said to improve impact resistance, and plate-like fillers, such as talc, mica and clay, which are said to improve elastic modulus, by high-speed stirring. Known (Japanese Patent Laid-Open No. 2002-80631: Patent Document 4). However, synthetic resins to be compounded include homopolypropylene and block polypropylene polyolefin resins, nylon 6 polyamide resins, and PET polyester resins, which are based on PEEK assuming an AT seal ring and calcium carbonate and plate However, even if the fracture resistance (brittleness) is improved, the wear resistance may be insufficient even if the fracture resistance (brittleness) is improved. In some cases, the breakage resistance and the wear resistance were not balanced.

Japanese Patent Laid-Open No. 5-262976 Japanese Patent Laid-Open No. 2001-49111 Japanese Patent Laid-Open No. H5-239350 JP 2002-80631 A

  Therefore, the object of the present invention is expected to be effective in the AT seal ring that is in sliding contact with the aluminum alloy, particularly in a small seal ring having an outer diameter of 30 mm or less. However, PEEK is reduced to 65 wt% or less. Providing an AT seal ring that has excellent wear resistance and low opponent attack even if it is reduced and does not break beyond the allowable elastic deformation when the joint is expanded and attached to the shaft. That is.

  As a result of diligent research in view of the above object, the present inventor selected calcium carbonate and talc as main fillers in addition to carbon fibers of a specific size as fillers for PEEK materials, and determined the size and amount of the filled powder. As a result of the optimization, it was found that an AT seal ring with significantly improved breakage resistance in addition to excellent wear resistance and low opponent attack properties was obtained, and the present invention was conceived.

  That is, the seal ring of the present invention is PEEK 65% by weight or less, carbon fiber 10-30% by weight with an average fiber diameter 3-10 μm, calcium carbonate powder with an average particle size 0.5-5 μm and a plate shape with an average plate diameter 0.1-5 μm. It is characterized by containing 10 to 35% by weight of talc powder. Quantitatively, the weight ratio of calcium carbonate powder / plate-like talc powder is preferably in the range of 0.2 to 1.2. Further, even if a part of the plate-like talc powder is replaced with scaly graphite having an average plate diameter of 10 μm or less, it is particularly preferable from the viewpoint of wear resistance.

  Since the calcium carbonate powder has a strong tendency to form an agglomerate when it becomes finer, it is still preferable to uniformly grind the calcium carbonate powder and the plate-like talc powder by high-speed agitation in order to pulverize the agglomerate.

  The seal ring of the present invention comprises PEEK 65% by weight or less, carbon fiber 10-30% by weight with an average fiber diameter of 3-10 μm, calcium carbonate powder with an average particle diameter of 0.5-5 μm, and plate-like talc powder with an average plate diameter of 0.1-5 μm 10 to 35% by weight in total, so that the amount of expensive PEEK used is reduced, and in addition to excellent strength and wear resistance due to the composite of carbon fiber and plate-like talc powder, uniformly dispersed calcium carbonate powder Has improved breakage resistance. For this reason, the seal ring of the present invention may break even when the joint part is expanded and attached to the shaft even if it is a small seal ring having an outer diameter of 30 mm or less, and the joint part exceeds the allowable elastic deformation amount. And can be easily attached to the shaft.

  PEEK used in the present invention and PEK, PEN and PPS which can replace part or all of them have excellent mechanical properties, electrical properties and chemical resistance in addition to high heat resistance. A well-known resin marketed can be used. Although both are expensive resins, it is possible to approach the market demand in terms of cost by limiting them to 65% by weight or less.

  Next, the carbon fiber used in the present invention has an average fiber diameter of 3 to 10 μm. In general, carbon fibers having an average fiber diameter of 1 to 30 μm and an average length of several tens of μm to several mm are commercially available. In particular, polyacrylonitrile (PAN) carbon fibers having an average fiber diameter of 3 to 10 μm are preferable. If the average fiber diameter is less than 3μm, uniform dispersion is difficult due to the entanglement of the fibers, and when kneading, the fiber breaks to become short fibers, and if it exceeds 10μm, the fiber strength is relatively low, so mechanical strength by fiber reinforcement The improvement in properties cannot be expected sufficiently. The blending ratio of such carbon fibers is 10 to 30% by weight. If it is less than 10% by weight, the mechanical properties are not sufficiently improved by fiber reinforcement, and if it exceeds 30% by weight, the melt flowability of the composite resin is remarkably lowered and it becomes difficult to injection-mold the seal ring.

  Next, the calcium carbonate powder as the filler used in the present invention has an average particle size of 0.5 to 5 μm. In the average particle diameter within this range, the breakage resistance is improved by the uniform dispersion of the calcium carbonate powder. If calcium carbonate powder having an average particle size of less than 1 μm is usually mixed, agglomeration between particles occurs and uniform dispersion becomes difficult, and if the particle size exceeds 5 μm, the breakage resistance is not sufficiently improved. However, when mixed and pulverized by high-speed stirring together with the plate-like talc powder added simultaneously with the calcium carbonate powder, the agglomerates are pulverized and uniformly dispersed even at an average particle size of 0.5 to 1 μm. Further, the plate-like talc powder added at the same time has an average plate diameter of 0.1 to 5 μm. The plate-like talc is effective in improving heat resistance, slidability and dimensional stability, and preventing sink marks and warpage during injection molding, in addition to improving mechanical properties mainly by improving elastic modulus. Similarly to the calcium carbonate powder, the plate-like talc is usually mixed only with a powder having an average particle diameter of less than 1 μm, and the particles are aggregated and uniform dispersion becomes difficult. On the other hand, if it exceeds 5 μm, the breakage resistance is significantly reduced. When mixed and pulverized by high-speed stirring, plate-like talc is pulverized more finely than calcium carbonate, and agglomerates are pulverized and evenly dispersed even with an average particle size of 0.1 to 1 μm.

  The blending ratio of these calcium carbonate powder and plate-like talc powder is 10 to 35% by weight in total. If it is less than 10% by weight, the wear resistance is insufficient, and the amount of inexpensive filler is small, so that the amount of expensive PEEK used is not sufficiently reduced, and if it exceeds 35% by weight, the melt fluidity of the composite resin is significantly reduced. At the same time, the pH increases due to the addition of calcium carbonate, and the base resin is easily gelled, which makes injection molding of the seal ring difficult.

  The seal ring of the present invention needs to be excellent in both fracture resistance and wear resistance, and it is not sufficient that only one of them is improved. From the viewpoint of a balance between fracture resistance and wear resistance, the ratio of the compounding ratio of the calcium carbonate powder and the compounding ratio of the plate-like talc powder is important. In the present invention, the calcium carbonate powder weight / plate-like talc powder weight ratio is in the range of 0.2 to 1.2. If the weight ratio is less than 0.2, the defect resistance due to calcium carbonate is not sufficiently improved, and if the weight ratio exceeds 1.2, the wear resistance becomes insufficient and the pH value increases due to calcium carbonate. Preferably it is set as the range of 0.3-1.1.

  Furthermore, in the seal ring of the present invention, a part of the plate-like talc powder can be replaced with scaly graphite having an average plate diameter of 10 μm or less in order to improve the sliding characteristics and further improve the wear resistance. However, when the average plate diameter of the flake graphite exceeds 10 μm, the breakage resistance of the seal ring is lowered. Further, the blending ratio of the flake graphite replaced with the plate-like talc powder is preferably less than 7% by weight.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1-4 (J1-4) and Comparative Examples 1-3 (H1-3)
Powdered PEEK, carbon fiber with an average fiber diameter of 6.5 μm, calcium carbonate with an average particle diameter of 1.4 μm, and plate-like talc with an average plate diameter of 3.2 μm are mixed in the proportions shown in Table 1 and first, the temperature is 400 ° C. in an extruder. The mixture was mixed under the conditions of a screw rotation speed of 50 rpm and a powder supply rotation speed of 65 rpm to produce a predetermined amount of pellets having a diameter of about 3 mm and a length of 3 to 4 mm. Next, a wear test test piece with a special step joint shape with a nominal diameter (outer diameter) of 60.0 mm, a width of 2.0 mm, and a thickness of 2.0 mm, and a nominal diameter (outer diameter) of 24.5 mm and a width of 1.8 mm. A test piece for breakage test having a thickness of 1.4 mm was injection molded using the pellets under conditions of a mold temperature of 170 ° C., a molding temperature of 340 to 420 ° C., an injection speed of 30 mm / sec, and a molding pressure of 130 MPa.

  The abrasion test was conducted using a thrust type abrasion tester schematically shown in FIG. This testing machine consists of a holder that fixes a seal ring that rotates at a constant speed in oil, and a holder that fixes an aluminum disk that presses against it with a constant surface pressure. This is done by measuring the amount of wear of the seal ring and the amount of wear of the aluminum disc. The conditions of the wear test were as follows: friction speed 6.7m / sec, contact surface pressure 1MPa, mating material JIS2024 aluminum alloy disk with surface roughness (Rz) 1μm, friction distance 44km, friction method ATF oil sliding, It happened. In addition, the sliding surface of the seal ring test piece was left as the injection-molded surface in order to make the situation close to that of the actual machine.

  Further, the breakage test was conducted using a dedicated testing machine schematically shown in FIG. The seal ring is expanded at a constant speed along the conical jig shown in FIG. 2, and the fracture resistance is evaluated by measuring the maximum inner diameter immediately before the seal ring breaks. Fracture resistance targeted by the present invention is equivalent to that of a commercially available seal ring comprising 70% by weight of PEEK, 20% by weight of carbon fiber, and 10% by weight of other fillers. Expressed as a percentage, with break resistance as 100.

  The wear test results and breakage test results of Examples 1 to 4 (J1 to 4) and Comparative Examples 1 to 3 (H1 to 3) in Table 1 are shown in the same table. Within the scope of the present invention, the amount of self-wear was 10 μm or less, and the fracture resistance was 100% or more.

Examples 5 to 7 (J5 to 7) and Comparative Examples 4 to 6 (H4 to 6)
A test piece for wear test and a test piece for breakage test were carried out with the composition of the same blending ratio as in Example 2 (J2) with the particle diameters or plate diameters of calcium carbonate powder and plate-like talc powder as shown in Table 2 Prepared in the same manner as in Example 2 (J2). In Examples 5 and 6 (J5, 6) and Comparative Example 4 (H4), the powder-sized raw material of Example 2 (J2) was mixed and pulverized by changing the stirring conditions by high-speed stirring with a Henschel mixer. . The wear test and breakage test were performed in the same manner as in Example 1, and the results are shown in the same table. When the average particle diameter of the calcium carbonate powder of the present invention is in the range of 0.5 to 5 μm and the average plate diameter of the plate-like talc powder is in the range of 0.1 to 5 μm, the self-wear amount is 10 μm or less and the fracture resistance is 100% or more. .

Example 8 (J8)
A test piece for wear test in the same manner as in Example 2 except that 1/2 (5% by weight) of the plate-like talc is replaced with scaly graphite having an average plate diameter of 7 μm in the composition ratio of Example 2 (J2). A test piece for breakage test was prepared. The wear test and breakage test were carried out in the same manner as in Example 1. As a result, the self-abrasion amount was 4 μm, the counterpart material wear amount was 7 μm, and the breakage resistance was 100%.

Examples 9-12 (J9-12)
Except for PEEK, the composition was the same as in Example 2 (J2). In Example 9 (J9), 1/3 (20% by weight) of PEEK was replaced with PEN. In Examples 10 to 12 (J10 to 12) By replacing all of PEEK with PEN (J10), PEK (J11), and PPS (J12), respectively, a test piece for wear test and a test piece for breakage test were produced in the same manner as in Example 2. The wear test and breakage test were performed in the same manner as in Example 1, and the results are shown in Table 3. As a result, the object of the present invention can be achieved even if any selected heat-resistant engineering plastic is replaced with PEEK.

It is a principal part schematic sectional drawing of a Matsubara type abrasion tester. It is the schematic of a seal ring exclusive use break test machine.

Explanation of symbols

1 Aluminum disc holder (fixed)
2 Holder for seal ring (fixed)
3 Aluminum disc 4 Seal ring for evaluation 5 Oil bath 6 Oil 7 Oil scattering prevention cover

Claims (3)

Polyetheretherketone resin 65 wt% or less, carbon fiber 10-30 wt% with an average fiber diameter 3-10 μm, calcium carbonate powder with an average particle diameter 0.5-5 μm and plate-like talc powder with an average plate diameter 0.1-5 μm in total 10 A composite resin seal ring comprising -35 wt% , wherein the calcium carbonate powder weight / plate talc powder weight ratio is in the range of 0.2 to 1.2 . 2. The composite resin seal ring according to claim 1, wherein a part or all of the polyether ether ketone is replaced with any one resin selected from the group consisting of polyether ketone, polyether nitrile, and polyphenylene sulfide. The composite resin seal ring according to claim 1 or 2 , wherein the calcium carbonate powder and the plate-like talc powder are uniformly mixed and pulverized by high-speed stirring in a dry method.

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