JP5845118B2 - Constant velocity universal boots - Google Patents

Description

  The present invention relates to a constant velocity universal joint boot. More specifically, the present invention relates to a boot for a silicone rubber constant velocity universal joint.

  With the recent high performance of automobiles, the use conditions of constant velocity universal joints tend to be severe. The constant velocity universal joint tends to increase the amount of heat generated by the constant velocity universal joint by requiring use conditions of higher torque and higher rotation. In addition, the constant velocity universal joint for drive shafts and the constant velocity universal joint for propeller shafts installed on the differential gear side have a layout that is closer to the exhaust pipe due to space saving, so the influence of radiant heat There is a tendency to receive greatly. As a result, the boots attached to the constant velocity universal joints are exposed to higher temperatures, and in the case of constant velocity universal joints that particularly require heat resistance, a silicone made of silicone rubber having excellent heat resistance. The use of rubber constant velocity universal joint boots is desired (Patent Document 1).

  In order to further increase the durability of the boot at high temperature, there is one in which cerium oxide, which is one of rare earths, is added to silicone rubber. It is known that heat resistance is improved by adding a cerium compound such as cerium oxide or cerium hydroxide to silicone rubber (Patent Document 2).

JP 2005-214395 A JP 2006-265456 A

  However, the availability of cerium oxide is unstable due to the limited production area, the price is likely to rise, and there is concern about the stable supply, which may hinder the use of boot materials.

  Accordingly, an object of the present invention is to obtain a boot having durability at a high temperature similar to that of the prior art by using a silicone rubber to which rare earth such as cerium oxide is not added.

  As a result of various experiments and researches to achieve such an object, the present inventors have come to know that durability at high temperatures is improved when Bengala, titanium oxide and barium zirconate are added to silicone rubber. .

The present invention is based on such knowledge. According to the first aspect of the present invention, in the boot for a constant velocity universal joint made of silicone rubber, bengara and titanium oxide are added to the silicone rubber.

According to a second aspect of the present invention, in the boot for a constant velocity universal joint made of silicone rubber according to the first aspect of the present invention, barium zirconate is further added.

According to a third aspect of the present invention, there is provided a large-diameter mounting portion for fixing the silicone rubber constant velocity universal joint boot according to the first or second aspect to an outer joint member of the constant velocity universal joint, and a constant velocity universal joint. A small-diameter mounting portion fixed to the shaft connected to the inner joint member, and a bellows portion having a plurality of peaks and valleys provided between the both mounting portions, and the curvature of the valley outer peripheral surface of the bellows portion is a peak outer peripheral surface It is smaller than the curvature of.

Further, in the invention described in claim 4, the silicone rubber constant velocity universal joint boot according to claim 1 or 2 is for a propeller shaft of an automobile, and an annular member mounted on an outer joint member of the constant velocity universal joint is provided. A large-diameter mounting portion fixed to the end portion, a small-diameter mounting portion fixed to a shaft connected to the inner joint member of the constant velocity universal joint, and a bent portion that is provided between the two mounting portions and curved in a U-shape. It consists of the bellows part which has.

According to the silicone rubber constant velocity universal joint boot made of the silicone rubber according to claim 1, it is possible to use two additives for a predetermined period of time, such as bengara and titanium oxide, which are generally easily and stably available at a relatively low cost. Although a slight crack was observed in the bellows valley portion in the double test, durability enough to satisfy the specifications was obtained in practical use.

  Further, according to the silicone rubber constant velocity universal joint boot according to claim 2 to which barium zirconate is added, durability at a high temperature can be improved as compared with the case where only bengara and titanium oxide are added. In the test twice as long as the predetermined time, no crack was observed, and durability equal to or higher than that obtained when cerium oxide was added was obtained.

  According to the silicone rubber constant velocity universal joint boot according to claim 3, it is possible to suppress the deformation of the compression side phase of the boot trough which is most easily affected when the constant velocity universal joint takes an operating angle. The durability of the boot can be further improved.

  Furthermore, according to the boot for a silicone rubber constant velocity universal joint for a propeller shaft of an automobile according to claim 4, since the bent portion curved in a U shape is formed in a large R shape, the constant velocity universal joint is rotated at a high speed. In this case, it is possible to suppress the swinging of the boot bent portion and improve the durability of the boot.

It is a partial cross section figure which shows the example of the constant velocity universal joint concerning this invention. It is a partial cross section figure which shows the other example of the constant velocity universal joint concerning this invention.

  Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.

The boot for a constant velocity universal joint made of silicone rubber according to the present invention is characterized in that Bengala and titanium oxide are added to the silicone rubber as the boot material. Here, the combination of only one of Bengala and titanium oxide cannot satisfy the durability required for boots, but the combination of Bengala and titanium oxide together increases the durability of the boots at high temperatures, The performance required for boots can be maintained. Here, it is preferable to use, for example, vinyl methyl silicone rubber (VQM) as the silicone rubber as the boot material. In this specification, “durability of boot” means bending fatigue due to deformation of the boot, wear due to interference, and the like.

  As a result of the experiment, it was found that the effect of adding 3 parts by weight with respect to 100 parts by weight of the silicone rubber is sufficient for the addition amount of Bengala and titanium oxide to the silicone rubber. Since the additive is added to improve the durability of the silicone rubber, if 3 parts by weight of Bengala and titanium oxide is sufficient with respect to 100 parts by weight of the silicone rubber, it will naturally be durable if more is added. Although the performance is improved, the excessive addition is wasteful and causes undesirable results. That is, if the amount added is too large, foreign matter will increase in the silicone rubber material, and there is a concern that the basic performance as a rubber will deteriorate.

Furthermore, in the boots for constant velocity universal joints made of silicone rubber according to the present invention, it was found that durability at high temperature is further improved by adding barium zirconate to silicone rubber in addition to the aforementioned bengara and titanium oxide. . That is, it was found that when not only Bengala and titanium oxide but also barium zirconate is added, durability at high temperatures is maintained even if the addition amount is reduced. When bengara, titanium oxide and barium zirconate are added, even if the added amount is 0.5 parts by weight with respect to 100 parts by weight of silicone rubber, a slight crack is observed in the bellows valley part. Durability to the extent that can be satisfied was also obtained in a test twice as long as the predetermined time. And if each addition amount of Bengala, titanium oxide and barium zirconate is at least 1 part by weight with respect to 100 parts by weight of silicone rubber, cracks are not recognized, and durability equal to or higher than that when cerium oxide is added. It was found that sex was obtained. The durability at this high temperature is the same for both 2 parts by weight and 3 parts by weight as long as 1 part by weight or more of Bengala, titanium oxide and barium zirconate is added to 100 parts by weight of silicone rubber. can get. Therefore, if a sufficient result can be obtained as a function as an additive, it is preferable to make the addition amount smaller, which is advantageous in terms of cost. That is, when adding bengara, titanium oxide and barium zirconate to silicone rubber, preferably bengara, titanium oxide and barium zirconate are each in the range of 1 to 3 parts by weight with respect to 100 parts by weight of silicone rubber. More preferably, it is in the range of 1 to 2 parts by weight.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, the silicone rubber constant velocity universal joint boot to which the present invention is applied is not particularly limited to the boot form, and has a bellows-like bent portion having a plurality of valleys as shown in FIG. Alternatively, a boot having a bent portion curved in a U shape as shown in FIG. 2 may be used.

(Test 1)
A boot having a bellows-like bent portion as shown in FIG. 1 is manufactured and mounted on a sliding tripod type constant velocity universal joint. , And the durability was evaluated. The results are shown in Table 1. Incidentally, the boot material is obtained by adding the additives and addition amounts shown in Table 1 to 100 parts by weight of silicone rubber, which is a crosslinked type of peroxide.

  From this test result, it can be seen that Examples 2 and 4 are preferable in Example 2 or Example 3 in which the blending amount is reduced from the viewpoint of cost because the state after operation twice as long as the predetermined time is free of cracks. On the other hand, in Example 1, although the amount of additive added was small, a slight crack was observed, but it is considered that the specification can be satisfied in practical use. Further, in Example 5, since barium zirconate was not added, a slight crack was observed, but it is considered that the specification can be satisfied in practical use.

Here, the bellows-like silicone rubber constant velocity universal joint boot 5a of FIG. 1 used in the test is fitted to the outer joint member 2a of the constant velocity universal joint 1a and fixed to the outer cylinder end (large diameter). (Attachment part) 6a, inner cylinder end part (small diameter attachment part) 7a fitted and fixed to the shaft 4a connected to the inner joint member 3a, and these outer cylinder end part 6a and inner cylinder end part 7a And a bellows-like bent part having a plurality of peaks and valleys connecting them, and covers the constant velocity universal joint 1a so as to be sealed. And the bellows shape of the boot 5a makes the curvature of the valley outer peripheral surface of a bellows part smaller than the curvature of a mountain outer peripheral surface. In other words, by increasing the radius of curvature of the bellows valley portion than the radius of curvature of the peak portion, the deformation of the compression side phase of the boot valley portion when taking the operating angle is suppressed, and the durability of the valley portion is improved. Yes. If the curvature of the outer peripheral surface of the valley is equal to or greater than the curvature of the outer peripheral surface of the mountain, the valley is largely crushed and a crack starting point is likely to occur. The silicone rubber constant velocity universal joint boot 5a has the outer cylinder end 6a fitted to the outer joint member 2a and fixed by the fastening band 11a or the like, while the inner cylinder end 7a is fixed to the inner joint member 3a. The shaft 4a is fixed with a fastening band 11b or the like. A boot groove 9a is formed on the outer peripheral surface of the portion for fixing the inner cylinder end 7a of the shaft 4a, and the inner cylinder end 7a is fitted into the boot groove 9a. Incidentally, by providing the annular protrusions 8a on both sides of the boot groove 9a, the inner cylinder end 7a in the boot groove 9a can be more firmly fixed to the shaft 4a.

(Test 2)
A boot having a bent portion curved in a U-shape as shown in FIG. 2 is manufactured and mounted on a sliding cross groove type constant velocity universal joint, with an operating angle of 5 deg, an ambient temperature of 150 ° C., and a rotational speed of 5000 rpm. Then, it was rotated for twice the predetermined time and evaluated for durability. The results are shown in Table 2. Incidentally, the boot material is obtained by adding the additives and addition amounts shown in Table 2 to 100 parts by weight of silicone rubber which is a crosslinked type of peroxide.

  From these test results, it can be seen that Examples 7 to 9 are preferable to be Example 7 or Example 8 in which the blending amount is reduced from the viewpoint of cost because the state after operation for a predetermined time is not cracked. On the other hand, in Example 6, since the amount of the additive added was small, a slight crack was observed, but it is considered that the specification can be satisfied in practical use. In Example 10, since barium zirconate was not added, a slight crack was observed, but it is considered that the specification can be satisfied in practical use.

Here, the silicone rubber constant velocity universal joint boot 5b having a bent portion curved in a U-shape in FIG. 2 used in the test is interposed through an annular member 10b attached to the outer joint member 2b of the constant velocity universal joint 1b. The outer joint member 2b and the shaft 4b connected to the inner joint member 3b are mounted so as to cover the constant velocity universal joint 1b. This boot 5b is a boot for a silicone rubber constant velocity universal joint of a propeller shaft of an automobile, and an outer cylinder end portion fixed to an end portion of an annular member 10b attached to an outer joint member 2b of the constant velocity universal joint 1b. (Large-diameter mounting portion) 6b, an inner cylinder end portion (small-diameter mounting portion) 7b fixed to the shaft 4b connected to the inner joint member 3b, and a bent portion 13 provided between them and curved in a U-shape. The bent portion 13 that is greatly curved in a U-shape suppresses the swing of the boot bent portion when the constant velocity universal joint 1b rotates at a high speed, and improves the durability of the boot.

The silicone rubber constant velocity universal joint boot 5b is sealed by fixing the outer tube end portion 6b to the annular member 10b attached to the outer joint member 2b. As a fixing method, as shown in FIG. 2, a recess 14 is provided in the annular member 10b, and the tip of the outer cylinder end 6b of the silicone rubber constant velocity universal joint boot 5b is fitted into the recess 14 so that the annular member is fitted. For example, a method of caulking the concave portion 14 of 10b can be given. In addition, the fixing method of this outer cylinder edge part 6b and the annular member 10b is an example, and is not restricted to this. That is, the outer cylinder end 6b may be fixed to the annular member 10b with a fastening band or the like, or the annular member 10b is molded in advance with the silicone rubber constant velocity universal joint boot 5b and attached to the outer joint member 2b. May be. Reference numeral 15 in the drawing is a groove for venting air so that the grease filled in the boot does not leak.

The inner cylinder end 7b of the silicone rubber constant velocity universal joint boot 5b is fixed and sealed to the shaft 4b. A boot groove 9b is formed on the outer peripheral surface of the portion for fixing the inner cylinder end 7b of the shaft 4b. The inner cylinder end 7b is fitted into the boot groove 9b and fixed by a fastening band 11b or the like. Further, by providing the annular protrusions 8b on both sides of the boot groove 9b, the inner cylinder end 7b in the boot groove 9b can be more firmly fixed to the shaft 4b.

5a, 5b Silicone rubber constant velocity universal joint boots made of silicone rubber

Claims (4)

Boots for constant velocity universal joints made of silicone rubber made of silicone rubber with added bengara and titanium oxide, and with no added rare earth such as cerium oxide. The silicone rubber constant velocity universal joint boot according to claim 1, further comprising barium zirconate. The boot includes a large-diameter mounting portion fixed to the outer joint member of the constant velocity universal joint, a small-diameter mounting portion fixed to the shaft connected to the inner joint member of the constant velocity universal joint, and the two mounting portions. 3. A silicone rubber constant velocity universal joint boot according to claim 1, comprising a bellows portion having a plurality of peaks and valleys, wherein a curvature of the outer peripheral surface of the bellows portion is smaller than a curvature of the outer peripheral surface of the peak portion. . The boot is for a propeller shaft of an automobile, and is connected to a large-diameter mounting portion fixed to an end of an annular member connected to an outer joint member of a constant velocity universal joint, and to an inner joint member of the constant velocity universal joint. The boot for a constant velocity universal joint made of silicone rubber according to claim 1 or 2, comprising a small diameter attachment portion fixed to the shaft and a bellows portion provided between the attachment portions and having a bent portion curved in a U shape.

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