JP2011111091A - Telescopic shaft for vehicle steering - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a telescopic shaft for vehicle steering, built in a vehicular steering mechanism to fit a male shaft to a female shaft non-rotatably and slidably while improving the permanent set-in fatigue resistance, causing less rattle, and enhancing the wear resistance. <P>SOLUTION: In the telescopic shaft 20 for the vehicle steering built in a vehicular steering mechanism to fit a male shaft 21 to a female shaft 22 in a non-rotatable and slidable manner, a resin layer 23 consisting of a cross-linked synthetic resin composition is provided between the male shaft and the female shaft. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a telescopic shaft for vehicle steering that is incorporated in a steering mechanism portion of a vehicle and has a male shaft and a female shaft fitted in a non-rotatable and slidable manner.

  FIG. 8 shows a general automobile steering mechanism 15. The steering mechanism 15 includes a steering column 4 attached to a member 1 on the vehicle body side via an upper bracket 2 and a lower bracket 3, a steering shaft 5 rotatably supported on the steering column 4, and the steering A steering wheel 6 mounted on the upper end of the shaft 5, an intermediate shaft 8 connected to the lower end of the steering shaft 5 via a cardan shaft joint 7, and a cardan shaft joint 9 connected to the intermediate shaft 8. A coupled pinion shaft 10, a steering rack shaft 11 coupled to the pinion shaft 10, and a steering rack support member 14 that supports the steering rack shaft 11 and is fixed to another frame 12 of the vehicle body via an elastic body 13. It consists of and.

The intermediate shaft 8 employs a telescopic shaft in which a male spline shaft 8a and a female spline shaft 8b are fitted (hereinafter referred to as a telescopic shaft 8). The telescopic shaft 8 is required to absorb the axial displacement generated when the automobile travels, and to transmit the displacement and vibration on the steering wheel 6.
In such a performance, the vehicle body has a sub-frame structure, and the member 1 that fixes the upper part of the steering mechanism 15 and the frame 12 to which the steering rack support member 14 is fixed are separated. This is required in the case of a structure in which the rack support member 14 is fastened and fixed to the frame 12 via an elastic body 13 such as rubber.

As another case, when the cardan shaft joint 9 is fastened to the pinion shaft 10, an extension function is required for the operator to contract the telescopic shaft 8 once and then fit it to the pinion shaft 10 to fasten it. The
Further, the steering shaft 5 at the upper part of the steering mechanism section 15 is also formed by fitting the male spline shaft 5a and the female spline shaft 5b (hereinafter referred to as the telescopic shaft 5). The telescopic shaft 5 is required to have a telescopic function that moves the position of the steering wheel 6 in the axial direction and adjusts the position in order to ensure an optimal driving posture for the driver to drive the automobile. A function to expand and contract in the direction is required.

Here, the telescopic shafts 5 and 8 can reduce the rattling noise at the fitting portions of the male shaft splines 5a and 8a and the female spline shafts 5b and 8b, reduce the rattling on the steering wheel 6, and It is required to reduce the sliding resistance when sliding in the axial direction.
Therefore, for example, as in Patent Document 1, a structure is proposed in which a resin layer made of a synthetic resin composition is provided on the sliding portion of the telescopic shaft, and the male shaft spline is slid relative to the female spline shaft through the resin layer. ing. Thus, by providing the resin layer, the telescopic shaft can slide smoothly due to the self-lubricating property and flexibility of the resin material.

  However, in long-term use, there is a risk that the wear due to the grease being applied to the resin layer or the flexibility of the resin material will cause settling and play. Further, as in Patent Document 2, when a filler is included for improving the settling resistance, when wear occurs due to long-term use, the filler is exposed on the friction surface, so that only the friction counterpart material is damaged. Otherwise, the sliding of the telescopic shaft may become unstable.

JP 2008-2630 A JP 2008-168890 A

  Therefore, the present invention has been made in view of the above circumstances, it is possible to suppress the occurrence of play by improving the wear resistance and sag resistance, and damage the friction counterpart material even if wear occurs, An object of the present invention is to provide a telescopic shaft for vehicle steering in which sliding performance does not deteriorate.

  To achieve the above object, a telescopic shaft for vehicle steering according to claim 1 is incorporated in a steering mechanism portion of a vehicle, and a telescopic shaft for vehicle steering in which a male shaft and a female shaft are non-rotatably and slidably fitted. In the method, a resin layer made of a synthetic resin composition subjected to a crosslinking treatment is provided between the male shaft and the female shaft.

  According to a second aspect of the present invention, in the telescopic shaft for vehicle steering according to the first aspect, the crosslinking treatment is performed by radiation. According to a third aspect of the present invention, in the telescopic shaft for vehicle steering according to the second aspect, the radiation is any one selected from α rays, β rays, γ rays, particle beams, electron beams, and ion beams. It is characterized by that.

  According to a fourth aspect of the present invention, in the telescopic shaft for vehicle steering according to any one of the first to third aspects, the synthetic resin composition is made of an engineering plastic or poly- acrylate represented by polyamide or polyphenylene sulfide. It consists of super engineering plastics represented by ether ether ketone (PEEK).

  The invention according to claim 5 is the telescopic shaft for vehicle steering according to any one of claims 1 to 4, wherein the synthetic resin composition includes triallyl isocyanurate, trimethylolpropane triacrylate, pentaerythritol. A crosslinking aid such as triacrylate or ethylene glycol dimethacrylate is included.

  According to a sixth aspect of the present invention, in the telescopic shaft for vehicle steering according to the fifth aspect, the blending amount of the crosslinking aid is 0.2 to 7 parts by mass with respect to 100 parts by mass of the resin. And

According to a seventh aspect of the present invention, in the telescopic shaft for vehicle steering according to any one of the first to sixth aspects, the resin layer is a resin sleeve provided on the outer periphery of the male shaft. To do.
The invention according to claim 8 is the telescopic shaft for vehicle steering according to any one of claims 1 to 7, wherein the resin layer is a resin film provided on an inner periphery of the female shaft. And

  According to the telescopic shaft for vehicle steering according to the present invention, the generation of backlash can be suppressed, and even if wear occurs, the friction counterpart material is not damaged or the sliding performance is not deteriorated. Can be obtained.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the component same as the structure shown in FIG. 8, and the description is abbreviate | omitted.
FIG. 1 is an exploded perspective view of a telescopic shaft for vehicle steering (hereinafter referred to as a telescopic shaft) according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a male spline shaft of the telescopic shaft of the first embodiment. .

As shown in FIG. 1, the telescopic shaft 20 of this embodiment is composed of a male spline shaft (male shaft) 21 and a female spline shaft (female shaft) 22 that are spline-fitted with each other.
As shown in FIG. 2, a resin sleeve 23 is fitted on the outer peripheral surface of the male spline shaft 21. The resin sleeve 23 may be fixed by press-fitting into the male spline shaft 21 after injection molding as a separate body, or may be formed by insert molding with the male spline shaft 21 as a core.

  The thickness of the resin sleeve 23 is preferably set in the range of 100 to 2000 μm. When the thickness of the resin sleeve 23 is less than 100 μm, it is difficult to ensure a certain strength or more, and there is a possibility that cracks or the like may occur during use. On the other hand, if the thickness of the resin sleeve 23 exceeds 2000 μm, the difference in linear expansion coefficient with the female spline shaft 22 may increase when the temperature rises, and the play may increase.

  The resin material of the resin sleeve 23 includes engineering plastics such as polyamide resin and polyphenylene sulfide (tensile strength of 60 MPa or more, Charpy impact value of 50 J / m or more, flexural modulus of 2.4 GPa or more), super engineering such as polyether ether ketone. Plastic (satisfying the above, ASTM D648 heat deformation temperature 150 ° C. or more) is suitable. The polyamide resin may be the same as the conventional one, and polyamide 6, polyamide 66 (nylon 66), polyamide 46 (nylon 46), polyamide 12 (nylon 12), polyamide 11 (nylon 11), polyamide 6-12 (nylon 6) -12) and the like.

  The base resin is known to increase in rigidity at a high temperature by increasing the molecular weight. However, as the molecular weight increases, the melt viscosity increases and the moldability decreases. From the viewpoint of productivity, injection molding is preferable as a method for forming the resin sleeve, and it is not preferable that the melt viscosity is increased. For this reason, it is preferable to use a starting base resin having a number average molecular weight of 30,000 or less, particularly 10,000 to 20,000.

  The base resin is preferably blended with a reinforcing material such as glass fiber or carbon fiber for reinforcement. The reinforcing material may be subjected to a surface treatment with a coupling agent or the like in order to enhance adhesion with the base resin or enhance dispersibility. The compounding amount of the reinforcing material varies depending on the type of the base resin, the type of the reinforcing material, or the shape of the resin sleeve, but is 10 to 50% by mass for glass fiber, preferably 25 to 40% by mass, and 10 to 40 for carbon fiber. The ratio is mass%, preferably 15 to 35 mass%. However, the reinforcing material can be unblended by increasing the degree of crosslinking.

  A crosslinking aid is added to the base resin. The type of the crosslinking aid is not limited as long as it acts as a crosslinking aid when the base resin is subjected to radiation crosslinking, but considering handleability and crosslinking performance, triallyl isocyanurate, trimethylpropane, Pentaerythritol triacrylate and ethylene glycol dimethacrylate are preferred. In order to obtain sufficient strength as a resin sleeve, the addition amount of the crosslinking aid is desirably 0.2 to 7 parts by mass, preferably 0.5 to 6 parts by mass with respect to 100 parts by mass of the base resin. . If the crosslinking aid is less than 0.2 parts by mass, the reinforcing effect is insufficient, and if it exceeds 7 parts by mass, the crosslinking density is too high and the toughness becomes poor.

  To the base resin, a heat stabilizer, a solid lubricant, a lubricating oil, a colorant, an antistatic agent, a release agent, a fluidity improver, a crystallization accelerator, etc. are appropriately added within a range not impairing the object of the present invention. May be.

  In order to obtain the elastic sleeve resin sleeve 23 of the present invention, first, a resin composition formed by blending a base resin with a crosslinking aid, a reinforcing material and other additives, preferably using an injection molding machine, is used. A molded body having a resin sleeve shape (for example, the shape shown in FIG. 1) is obtained.

  In order to obtain a resin composition for molding, each component may be supplied separately to a melt mixer, and each component is mixed in advance by a mixer such as a Henschel mixer or a ribbon blender and then the melt mixer. May be supplied. As the melt mixer, any apparatus such as a single-screw or twin-screw extruder, a mixing roll, a pressure kneader, and a Brabender blast graph can be used.

  The molded body obtained above is then crosslinked by irradiation with radiation. The radiation is not limited as long as the base resin can be cross-linked, and α rays, β rays, γ rays, particle rays, electron beams, ion beams, and the like can be appropriately selected. This radiation irradiation is performed in an oxygen-free atmosphere, for example, in an inert gas atmosphere such as argon gas in consideration of oxidative degradation of the resin. It is also possible to carry out under vacuum. At this time, the degree of crosslinking can be adjusted by the radiation intensity and the irradiation time, or only the surface can be crosslinked. When only the surface is cross-linked, the wear resistance can be improved while maintaining the elasticity and impact resistance due to the uncrosslinked portion.

  In addition, for example, a polyamide resin has a large difference in rigidity with a number average molecular weight of around 100,000 as a boundary. Therefore, also in the present invention, crosslinking is performed by irradiation with radiation so that the number average molecular weight of the base resin after irradiation is 100,000 or more, preferably 300,000 or more. Accordingly, the radiation irradiation conditions in the present invention are appropriately selected according to the composition of the resin composition, the shape of the resin sleeve (particularly the size), etc., so that the number average molecular weight of the base resin after irradiation is 100,000 or more. Is done.

  In radiation crosslinking, free radicals are generated upon irradiation, and when exposed to the atmosphere (oxygen atmosphere) with the free radicals remaining, the residual free radicals combine with oxygen and cause material deterioration. Therefore, the crosslinked resin sleeve is heat-treated in an oxygen-free atmosphere. The heat treatment conditions are not limited as long as they do not cause deterioration due to heat, but are suitable at 50 to 180 ° C. for 1 to 48 hours.

  The resin sleeve 23 thus obtained is suppressed in oxygen deterioration by heat treatment in an oxygen-free atmosphere, and has excellent rigidity and durability.

The above-mentioned cross-linking by radiation may cross-link the entire resin sleeve 23 uniformly, but only a reinforcing portion of the resin sleeve 23 may be partially cross-linked.
In order to partially cross-link, a method of irradiating radiation other than the reinforcing portion of the resin sleeve by masking with a shielding member such as metal, ceramics or resist, or a method of irradiating the spot with an ion beam, etc. Can be adopted. Also in this case, the degree of cross-linking and the cross-linking depth can be adjusted by irradiation intensity and irradiation time.

  In the first embodiment of FIGS. 1 and 2, the telescopic shaft 20 in which the resin sleeve 23 is fitted to the outer peripheral surface of the male spline shaft 21 has been described. However, as shown in the second embodiment of FIG. A resin film 24 made of a synthetic resin composition may be formed on the inner peripheral surface of the spline shaft 22 with conditions such as thickness, the base resin, and a filler similar to those of the resin sleeve 23.

  Even in this case, it is possible to suppress the occurrence of play by improving the wear resistance and sag resistance, and even if wear occurs, the friction counterpart material may be damaged or the sliding performance may be reduced. It is possible to obtain a telescopic shaft for vehicle steering that is absent.

  Hereinafter, although the synthetic resin composition which concerns on this invention is further demonstrated as an Example and a comparative example, this invention is not limited to this.

[Examples and Comparative Examples]
(1) Manufacture of disk test piece The disk test piece of the example is a pellet of polyamide 66 (2020B manufactured by Ube Industries) and triallyl isocyanurate (manufactured by Nippon Kasei Co., Ltd.) )) Was mixed in an amount of 1.0% by mass and charged into a twin-screw extruder, and extrusion kneading was carried out at a kneading temperature of 280 to 290 ° C. to produce molding pellets. And the pellet for shaping | molding was thrown into the in-line screw type injection molding machine, and it shape | molded in the disk (refer FIG. 4). Thereafter, the molded body was placed in an electron beam irradiation apparatus, and the whole was irradiated with an electron beam under vacuum. The total amount of electron beam irradiation was 100 kGy. Then, after hold | maintaining the molded object after bridge | crosslinking at 120 degreeC in vacuum for 12 hours, it cooled gradually to room temperature.
The disc test piece of the comparative example was molded into a disc similar to the example by putting pellets of polyamide 66 (2020B manufactured by Ube Industries, Ltd.) into an in-line screw type injection molding machine.

(2) Wear test As shown in FIG. 4, a vertical load F of 49 N is applied to the bearing steel ball 31 placed on the disk specimen 30 and the steel ball 31 is slid at a speed of 10 mm / s. The abrasion test was performed by sliding at a distance of 5 mm (reciprocating 10 mm). The number of reciprocating slides is 50,000 and the total sliding distance is 500 m. The steel ball 31 used has a diameter of 3/8 inch and the material is SUJ2 (no heat treatment). Further, grease lubrication is performed between the steel ball 31 and the disk test piece 30. And the relative value was calculated | required by making the measured value of the polyamide 66 resin disc (comparative example) which has not performed radiation crosslinking into 100%. The results are shown in FIG.

  As is clear from FIG. 5, it can be seen that compared with the wear depth of the unirradiated test piece, the wear of the irradiated test piece is suppressed. This indicates that the abrasion resistance of the resin material is improved by the crosslinking treatment by electron beam irradiation.

(3) Compression Creep Test As shown in FIG. 6, a disk test piece 30 having a thickness of 3 mm is sandwiched between a pair of compression jigs 41, 41, and a compressive stress P is applied in the thickness direction of the disk test piece 30. The anti-sag property was evaluated. The compressive stress P is 40 Mpa, and the compression time is 3 hours. The test ambient temperature is 150 ° C. And the relative value was calculated | required by making the measured value of the polyamide 66 resin disc (comparative example) which has not performed radiation crosslinking into 100%. The results are shown in FIG. The compression sag amount ε (%) in the figure is a value calculated by the following equation (1).
ε = [(t0−t1) / t0] .100 (1)
t0: initial thickness t1: thickness after test

  As is apparent from FIG. 7, it can be seen that the compressed strain of the irradiated test piece is suppressed as compared with the compressive strain of the unirradiated test piece. Thus, it was shown that the sag resistance of the resin material was improved by the crosslinking treatment by electron beam irradiation.

1 is an exploded perspective view of a telescopic shaft for vehicle steering according to a first embodiment of the present invention. It is a transverse cross section of the male axis of a 1st embodiment concerning the present invention. It is a cross-sectional view of the female shaft of the second embodiment according to the present invention. It is a figure explaining an abrasion test method. It is a graph which shows the result of an abrasion test. It is a figure explaining the compression creep test method. It is a graph which shows the result of a compression creep test. It is the figure which showed schematically the steering mechanism part of a motor vehicle.

  DESCRIPTION OF SYMBOLS 1 ... Member on the vehicle body side, 2 ... Upper bracket, 3 ... Lower bracket, 4 ... Steering column, 5 ... Steering shaft, 6 ... Steering wheel, 7 ... Cardan shaft joint, 9 ... Cardan shaft joint, 10 ... Pinion shaft, 11 ... steering rack shafts 11 and 12 ... another frame of the vehicle body, 13 ... elastic body, 14 ... steering rack support member, 15 ... steering mechanism section, 20 ... telescopic shaft (vehicle steering telescopic shaft, steering shaft, intermediate shaft), DESCRIPTION OF SYMBOLS 21 ... Male spline shaft (male shaft), 22 ... Female spline shaft (female shaft), 23 ... Resin sleeve (resin layer), 24 ... Resin film (resin layer), 30 ... Disc test piece, 31 ... Bearing steel ball 41 ... Compression jig

Claims (8)

In a vehicle steering mechanism, a telescopic shaft for vehicle steering in which a male shaft and a female shaft are non-rotatably and slidably fitted,
A telescopic shaft for vehicle steering, wherein a resin layer made of a synthetic resin composition subjected to a crosslinking treatment is provided between the male shaft and the female shaft.   The telescopic shaft for vehicle steering according to claim 1, wherein the cross-linking treatment is performed by radiation.   The telescopic shaft for vehicle steering according to claim 2, wherein the radiation is any one selected from α rays, β rays, γ rays, particle rays, electron beams, and ion beams.   The said synthetic resin composition consists of super engineering plastics represented by engineering plastics represented by polyamide and polyphenylene sulfide, or polyetheretherketone, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. Telescopic shaft for vehicle steering.   The synthetic resin composition includes a crosslinking aid such as triallyl isocyanurate, trimethylolpropane triacrylate, pentaerythritol triacrylate, or ethylene glycol dimethacrylate. The telescopic shaft for vehicle steering according to 1.   The telescopic shaft for vehicle steering according to claim 5, wherein the amount of the crosslinking aid is 0.2 to 7 parts by mass with respect to 100 parts by mass of the resin.   The telescopic shaft for vehicle steering according to any one of claims 1 to 6, wherein the resin layer is a resin sleeve provided on an outer periphery of the male shaft.   The telescopic shaft for vehicle steering according to any one of claims 1 to 7, wherein the resin layer is a resin film provided on an inner periphery of the female shaft.

Images