JP2006300260A - Telescopic shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a telescopic shaft having excellent durability by enhancing abrasion resistance of a sliding part. <P>SOLUTION: In a telescopic shaft in which a steering shaft of a vehicle is assembled, a male shaft and a female shaft are non-rotatably and sildably fitted to each other and torque is transmitted when the outer peripheral part of the male shaft and the inner peripheral part of the female shaft are brought into contact with each other and rotated, a grease including a urea compound as a thickener and containing at least one of molybdenum disulfide and organic molybdenum compounds or a grease including a urea compound as a thickener and containing metallic soap in an amount of 3-10% by mass relative to the total amount of the grease is enclosed in a clearance between the outer peripheral part of the male shaft and the inner peripheral part of the female shaft. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a telescopic shaft incorporated in a steering shaft or the like of a vehicle.

  Conventionally, the steering mechanism part of an automobile absorbs the displacement in the axial direction that occurs when the automobile travels, and the expansion and contraction is a spline fit between the male shaft and the female shaft in order not to transmit the displacement or vibration on the steering wheel. The shaft is used as part of the steering mechanism. The telescopic shaft is required to reduce the sliding resistance when the spline portion slides in the axial direction.

  For this reason, a nylon film is coated on the male spline portion of the telescopic shaft, and grease is applied to the sliding portion to reduce the sliding resistance. In addition, a ball is disposed through an elastic body between the groove portion of the inner shaft and the ball in the groove portion provided on the outer peripheral portion of the inner shaft and the inner peripheral portion of the outer shaft. 2. Description of the Related Art A vehicle steering telescopic shaft that reduces the sliding load between a male shaft and a female shaft by rolling the ball and restrains the ball during rotation to transmit torque (see Patent Document 1) ). Further, in this vehicle steering telescopic shaft, a male groove and a female groove having a combined cross section with some play are provided in the inner shaft and the outer shaft in order to enable transmission of torque even when the ball is broken. .

JP 2001-50293 A

  However, even with such a spline-fitted telescopic shaft, the sliding portion may be worn when expanding and contracting in the axial direction, and play may occur in the rotational direction, which may adversely affect the steering feeling. This invention is made | formed in view of such a situation, Comprising: It aims at providing the expansion-contraction shaft which improves the abrasion resistance of a sliding part and is excellent in durability.

In order to achieve the above object, the present invention provides the following telescopic shafts.
(1) Built in a steering shaft of a vehicle, the male shaft and the female shaft are fitted in a non-rotatable and slidable manner, and the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft contact each other and rotate. In the telescopic shaft that transmits torque during
The gap between the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft is filled with grease containing a urea compound as a thickener and containing at least one of molybdenum disulfide and an organic molybdenum compound. Telescopic shaft.
(2) Built in the steering shaft of the vehicle, the male shaft and the female shaft are fitted in a non-rotatable and slidable manner, and the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft are in contact with each other for rotation. In the telescopic shaft that transmits torque during
A grease containing a urea compound as a thickening agent and metal soap in a proportion of 3 to 10% by mass of the total amount of grease is sealed in a gap between the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft. The telescopic axis.
(3) The telescopic shaft according to (1) or (2), wherein the urea compound is a urea compound represented by the following general formula [I].

_(Wherein, R 1, _{R 3} is more than 50 mole% of the sum of _{R 1} and _{R 3} is an alicyclic aliphatic hydrocarbon and an aromatic hydrocarbon group, _{R 2} is an aromatic 6 to 15 carbon atoms It is a trivalent hydrogen group.)

  In the telescopic shaft of the present invention, since the encapsulated grease contains a specific thickener and additive, the wear of the sliding portion is small, the durability is excellent, and the deterioration of the steering feeling can be prevented.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a side view of a steering mechanism portion of an automobile to which an extendable shaft according to an embodiment of the present invention is applied. In FIG. 1, an upper steering shaft portion 120 (including a steering column 103 and a steering shaft 104 rotatably supported by the steering column 103 is attached to a member 100 on the vehicle body side via an upper bracket 101 and a lower bracket 102. ), A steering wheel 105 attached to the upper end of the steering shaft 104, a lower steering shaft portion 107 connected to the lower end of the steering shaft 104 via a universal joint 106, and a steering shaft joint 108 to the lower steering shaft portion 107. A pinion shaft 109 connected to the pinion shaft, a steering rack shaft 112 connected to the pinion shaft 109, and the steering rack shaft 112 to support the steering rack shaft 112 and to the other frame 110 of the vehicle body. Steering mechanism from a fixed steering rack support member 113 through the body 111 is formed.

  Further, the lower steering shaft portion 107 and the upper steering shaft portion 120 are provided with telescopic shafts. As the telescopic shaft, for example, as shown in FIGS. 2 and 3, a female spline is formed on the inner peripheral surface of the female shaft 6, and the male shaft 5 is a spline having a male spline formed on the outer peripheral surface thereof. A sliding portion 20 and a shaft portion 21 having a smaller diameter than the spline sliding portion 20 are provided. The female shaft 6 includes a retaining portion 30 at its end to prevent the sliding portion 20 of the male shaft 5 from coming out. Further, the polyamide film is coated except for the portion 20a on the retaining portion side of the spline sliding portion 20.

  The telescopic shaft can be configured as shown in FIGS. In this telescopic shaft, a female shaft 42 is splined or serrated to the male shaft 41. A cylindrical seat 43 for inserting the diameter-expanding member 46 is formed on the inner peripheral surface of the end of the male shaft 41, and an adjustment screw 47 is inserted into a part of the seat 43. A through hole 44 is formed in the radial direction. At the end of the female shaft 42, a through hole 45 for inserting the adjustment screw 47 is formed in the radial direction corresponding to the through hole 44. In addition, a diameter-expanding member 46 for pressing the male shaft 41 in the radial direction is inserted into the seat 43 of the male shaft 41, and the diameter-expanding member 46 is expanded in diameter. An adjustment screw 47 is screwed in the radial direction. The diameter-expanding member 46 is provided with a screwing portion 48 having a female screw in the radial direction for screwing with the adjusting screw 47, and the adjusting screw 47 is opposed to the screwing portion 48. The receiving part 49 which supports the front-end | tip part is provided. The threaded portion 48 and the receiving portion 49 each have a convex circumferential portion that contacts the inner cylindrical seat portion 43 of the male shaft 41 on the outer diameter side. Further, the diameter expanding member 46 is provided with a connecting portion 50 that integrally connects the screwing portion 48 and the receiving portion 49 so as to be elastically deformable in the radial direction.

  In this telescopic shaft, the female shaft 42 is spline-fitted to the male shaft 41 and assembled, and the through holes 44 and 45 are aligned in the radial direction and the adjusting screw 47 is tightened through the through holes 44 and 45 in the radial direction. When moved inward, the radial interval between the threaded portion 48 and the receiving portion 49 of the diameter-expanding member 46 increases, and the male shaft 41 is pressed radially outward against the female shaft 42. By adjusting the tightening force of the adjusting screw 47, the radial pressing force of the male shaft 41 with respect to the female shaft 42 can be adjusted, thereby easily adjusting the sliding resistance of both the shafts 41 and 42. In addition, it is possible to reliably prevent the shafts 41 and 42 from rattling. Moreover, even after the shafts 41 and 42 are assembled, the sliding resistance can be easily adjusted, so that the work efficiency can be improved. Note that a caulking is formed in advance in the portion indicated by the reference numeral 51 of the threaded portion 48 of the diameter expanding member 46 in order to prevent the adjustment screw 47 from loosening.

  Further, the telescopic shaft can be configured as shown in FIGS. On the outer peripheral surface of the male shaft 61, three axial grooves 63 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction extend. Correspondingly, three axial grooves 65 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 62. Between the axial groove 63 of the male shaft 61 and the axial groove 65 of the female shaft 62, a plurality of rigid spherical bodies 67 (rolling bodies, which roll when the shafts 61 and 62 move in the axial direction relative to each other). Ball) is installed to roll freely. The axial groove 65 of the female shaft 62 has a substantially arc-shaped cross section or a Gothic arch shape. The axial groove 63 of the male shaft 61 includes a pair of inclined planar side surfaces 63a and a bottom surface 63b formed flat between the pair of planar side surfaces 63a.

  A leaf spring 69 for contacting and preloading the spherical body 67 is interposed between the axial groove 63 of the male shaft 61 and the spherical body 67. As shown in FIG. 6B, the leaf spring 69 is separated from the spherical body-side contact portion 69a that makes contact with the spherical body 67 at two points, and is spaced from the spherical body-side contact portion 69a at a predetermined interval in the circumferential direction. In addition, the groove surface side contact portion 69b that contacts the planar side surface 63a of the axial groove 63 of the male shaft 61, and the spherical body side contact portion 69a and the groove surface side contact portion 69b are elastically moved away from each other. It has a biasing portion 69 c that biases, and a bottom portion 69 d that faces the bottom surface 63 b of the axial groove 63. The urging portion 69c is a substantially U-shaped bent shape that is bent in a substantially arc shape, and the spherical-body-side contact portion 69a and the groove surface-side contact portion 69b are mutually connected by the bent urging portion 69c. Can be elastically biased so as to be separated from each other.

  As shown in FIG. 7, three axial grooves 64 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the outer circumferential surface of the male shaft 61. Correspondingly, three axial grooves 66 that are equally arranged at intervals of 120 degrees (phase) in the circumferential direction are formed to extend on the inner peripheral surface of the female shaft 62. A plurality of rigid cylindrical bodies 68 (sliding bodies) that slide between the axial grooves 64 of the male shaft 61 and the axial grooves 66 of the female shaft 62 when the shafts 61 and 62 move relative to each other in the axial direction. , A needle roller) is interposed with a minute gap. These axial grooves 64 and 66 have a substantially circular arc shape or a Gothic arch shape in cross section.

  Further, as shown in FIG. 6, a stopper plate 70 with an elastic body is provided at the end of the male shaft 61, and the spherical body 67, the cylindrical body 68, and the plate spring 69 are formed by the stopper plate 70 with an elastic body. Prevents falling off.

  In this telescopic shaft, a spherical body 67 is interposed between the male shaft 61 and the female shaft 62, and the spherical body 67 is preloaded by the leaf spring 69 to the extent that there is no backlash with respect to the female shaft 62. At the time of non-transmission, the play between the male shaft 61 and the female shaft 62 can be surely prevented, and when the male shaft 61 and the female shaft 62 move relative to each other in the axial direction, there is no play. It can slide with a stable sliding load. At the time of torque transmission, the leaf spring 69 is elastically deformed to constrain the spherical body 67 in the circumferential direction, and the three rows of cylindrical bodies 68 interposed between the male shaft 61 and the female shaft 62 serve as the main torque transmission roles. Fulfill. For example, when torque is input from the male shaft 41, the preload of the leaf spring 69 is applied in the initial stage, so there is no backlash, and the leaf spring 69 generates a reaction force against the torque and transmits the torque. . At this time, overall torque transmission is performed in a state where transmission torque and input torque between the male shaft 61, the leaf spring 69, the spherical body 67, and the female shaft 62 are balanced. When the torque further increases, the clearance in the rotational direction of the male shaft 61 and the female shaft 62 via the cylindrical body 68 disappears, and the subsequent torque increase is transmitted via the male shaft 61 and the female shaft 62 to the cylindrical body. 68 communicates. Therefore, the play in the rotational direction of the male shaft 6 and the female shaft 62 can be reliably prevented and torque can be transmitted in a highly rigid state.

  The first grease or the second grease shown below is sealed in the gap between the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft of each telescopic shaft configured as described above.

(First grease)
The first grease contains a urea compound as a thickener and contains at least one of molybdenum disulfide and an organic molybdenum compound as an essential additive.

  The type of grease base oil is not limited, but mineral oils and synthetic lubricants can be suitably used. Mineral oils are not limited, but for example, paraffinic mineral oils, naphthenic mineral oils and mixed oils thereof can be used, especially vacuum distillation, oil removal, solvent extraction, hydrocracking. It is preferable to use a combination of solvent dewaxing, sulfuric acid washing, clay refining, hydrogenation refining and the like. In addition, although synthetic lubricating oil is not limited, for example, synthetic hydrocarbon oil, ether oil, ester oil, and fluorine oil can be used. Specifically, poly α-olefin oil or the like as the synthetic hydrocarbon oil, dialkyl diphenyl ether oil, alkyl triphenyl ether oil, alkyl tetraphenyl ether oil or the like as the ether oil, diester oil or neopentyl type as the ester oil. Examples thereof include polyol ester oils, complex ester oils thereof, aromatic ester oils, and the like. These lubricating oils may be used alone or in appropriate combination of a plurality of types.

Moreover, it is preferable that kinematic viscosity in 40 degreeC is 20-185 mm < ² > / s, and, as for base oil, it is more preferable that it is 24-132 mm < ² > / s. If the kinematic viscosity is less than 20 mm ² / s (40 ° C.), the effect of improving the wear resistance is not obtained. If the kinematic viscosity exceeds 185 mm ² / s (40 ° C.), the base oil hardly enters the sliding contact portion. It becomes difficult to suppress the stick-slip phenomenon on the sliding surface where the outer peripheral portion and the inner peripheral portion of the female shaft contact each other.

  Examples of the thickener urea compound include monourea, diurea, triurea, tetraurea, urethane, and sodium terephthalate organic compounds. These thickeners may be used alone or in admixture of two or more. The urea compound forms a protective film on the metal surface during sliding, and can impart better friction characteristics.

  The content of the thickener is preferably 5 to 30% by mass of the total amount of grease. If it is less than 5% by mass, it is difficult to maintain the grease state, and if it exceeds 30% by mass, it becomes too hard to obtain a sufficient lubrication state. In particular, when the content is 15% by mass or more, the formation of the protective film is further strengthened and the stick-slip phenomenon can be suppressed.

  Among urea compounds, a diurea compound is a thickener that can be suitably used for a telescopic shaft for vehicle steering because it has heat resistance, excellent oil retention, and is inexpensive. Among these, diurea compounds represented by the following general formula [I] are preferable.

In the formula, R ₂ represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R ₁ and R ₃ represent a hydrocarbon group or a condensed hydrocarbon group. The carbon number of the condensed hydrocarbon group is preferably 9-19. In R ₁ and R ₃ , the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and the aliphatic hydrocarbon group may be an alicyclic aliphatic hydrocarbon group. Further, R ₁ and R ₃ may be the same or different.

Furthermore, in R ₁ and R ₃ , the total of the alicyclic aliphatic hydrocarbon group and the aromatic hydrocarbon group is preferably 50 mol% or more. Since such a urea compound has a smaller area and volume per crystal than other urea compounds, when it is enclosed in a telescopic shaft, it is densely present on the surface of the sliding surface even in the boundary lubrication state and is stronger. It becomes a protective film.

In the diurea compound represented by the general formula [I], a total of 2 moles of monoamines containing R ₁ or R ₃ in the skeleton are contained in _{one base of the} diisocyanate containing R ₂ in the skeleton in the base oil. It is obtained by reacting at a ratio.

As the diisocyanate containing R ₂ in the skeleton, diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, dimethyldiphenylene diisocyanate, or alkyl-substituted products thereof can be preferably used.

Examples of monoamines containing a hydrocarbon group (including aromatic hydrocarbon group and alicyclic aliphatic hydrocarbon group) as R ₁ or R ₃ in the skeleton include aniline, cyclohexylamine, octylamine, toluidine, dodecylaniline, octadecylamine, Hexylamine, heptylamine, nonylamine, ethylhexylamine, decylamine, undecylamine, dodecylamine, tetradecylamine, pentadecylamine, nanodecylamine, eicodecylamine, oleylamine, linoleylamine, linolenylamine, methylcyclohexylamine, ethylcyclohexyl Amine, dimethylcyclohexylamine, diethylcyclohexylamine, butylcyclohexylamine, propylcyclohexylamine, amylcyclohexylamine, cyclohexane Butylamine, benzylamine, benzhydrylamine, phenethylamine, methyl benzylamine, biphenyl amine, phenyl isopropylamine, can be suitably used phenylhexylamine like.

Further, as monoamines containing a condensed ring hydrocarbon group in the skeleton as R ₁ or R ₃ , for example, indene amine compounds such as aminoindene, aminoindane, and amino-1-methyleneindene, aminonaphthalene (naphthylamine), aminomethylnaphthalene Aminoethylnaphthalene, aminodimethylnaphthalene, aminocadalene, aminovinylnaphthalene, aminophenylnaphthalene, aminobenzylnaphthalene, aminodinaphthylamine, aminobinaphthyl, amino-1,2-dihydronaphthalene, amino-1,4-dihydronaphthalene, aminotetrahydro Naphthalene-based amino compounds such as naphthalene and aminooctalin, condensed bicyclic amine compounds such as aminopentalene, aminoazulene and aminoheptalene, aminofluorene, amino- -Aminofluorene-based amine compounds such as phenylfluorene, aminoanthracene, aminomethylanthracene, aminodimethylanthracene, aminophenylanthracene, anthracene-based amine compounds such as amino-9,10-dihydroanthracene, aminophenanthrene, amino-1,7 Phenanthreneamine compounds such as dimethylphenanthrene and aminoretene, condensed bicyclic amine compounds such as aminobiphenylene, amino-s-indacene, amino-as-indacene, aminoacenaphthylene, aminoacenaphthene and aminophenalene, aminonaphthacene , Aminochrysene, aminopyrene, aminotriphenylene, aminobenzoanthracene, aminoaceanthrylene, aminoaceanthrene, aminoacephenanthrylene, amino Condensed tetracyclic amine compounds such as noacephenanthrene, aminofluoranthene, and aminopreaden, condensed pentacyclic amines such as aminopentacene, aminopentaphene, aminopicene, aminoperylene, aminodibenzoanthracene, aminobenzopyrene, and aminocholanthrene A compound, a condensed polycyclic (six or more ring) amine compound such as aminocoronene, aminopyrantolen, aminodoolanthrene, aminoisoviolanthrene, aminoobalene and the like are preferably used.

  Molybdenum disulfide and the organic molybdenum compound both function as extreme pressure additives, and are added in an amount of 0.5 to 10% by mass, preferably 0.5 to 5% by mass, based on the total amount of grease. Molybdenum disulfide is widely used as a solid lubricant. This molybdenum disulfide has a layered lattice structure, and can be easily sheared into a thin layer by a sliding motion to prevent metal contact. If the amount is less than 0.5% by mass, the effect cannot be expected, and even if the amount exceeds 10% by mass, the effect is saturated.

  In addition, the organic molybdenum compound can be adsorbed on a metal surface which is a sliding surface to form a highly reactive coating (reactive film layer) and improve the wear resistance. Among organic molybdenum compounds, molybdenum dithiophosphate (Mo-DTP), molybdenum dithiocarbamate (Mo-DTC) and the like are preferable because of their high effects.

Organometallic compounds such as metal dihydrocarbyl dithiophosphates, metal dihydrocarbyl dithiocarbamates, and naphthenates that form the same reaction film layer can be used in combination as necessary. Examples of metal dihydrocarbyl dithiophosphates are metal dihydrocarbyl dithiophosphates in which each hydrocarbyl group is C _{4 to} C ₂₀ , such as zinc dimethyl dithiophosphate, zinc butyl isooctyl dithiophosphate, zinc di (4-methyl- 2-pentyl) dithiophosphate, zinc di (tetrapropenylphenyl) dithiophosphate, zinc (2-ethyl-1-hexyl) dithiophosphate, zinc (isooctyl) dithiophosphate, zinc (ethylphenyl) dithiophosphate, zinc Preferred are (amyl) dithiophosphate, zinc di (hexyl) dithiophosphate, or metals such as zinc, zinc, lead, cadmium, and antimony.

The metal dihydrocarbyl dithiocarbamates are metal dihydrocarbyl dithiocarbamates in which each hydrocarbyl group is C _{4 to} C ₂₀ , such as zinc dimethyl dithiocarbamate, zinc butyl isooctyl dithiocarbamate, zinc di (4-methyl-2-pentyl). Dithiocarbamate, zinc di (tetrapropenylphenyl) dithiocarbamate, zinc (2-ethyl-1-hexyl) dithiocarbamate, zinc (isooctyl) dithiocarbamate, zinc (ethylphenyl) dithiocarbamate, zinc (amyl) dithiocarbamate, zincdi (hexyl) ) In addition to the above zinc (zinc), dithiocarbamate or metals such as lead, cadmium, antimony, nickel and iron are preferred.

  In addition, polytetrafluoroethylene (PTFE) capable of obtaining the same effect can also be used. Since the cohesive energy of polytetrafluoroethylene is small compared to other polymer compounds and the critical interfacial tension is very low, the polytetrafluoroethylene particles present in the sliding part become minute flakes due to the shear stress due to sliding, It is easy to spread on the mating material of the sliding part, thereby imparting excellent lubricity to the sliding part. Among these, polytetrafluoroethylene having a molecular weight of several thousand to several hundred thousand is preferable.

  If necessary, the grease may contain additives usually added to the grease, such as load bearing additives, antioxidants, rust inhibitors, and anticorrosives. The total amount added is preferably 10% by mass or less of the total amount of grease.

  Moreover, in order to ensure a suitable fluidity | liquidity, it is preferable that a grease is set to 220-340 by a penetration degree.

(Second grease)
The second grease contains a urea compound as a thickener and metal soap added at a ratio of 3 to 10% by mass of the total amount of grease.

Incidentally, the base oil is 20~200mm ² / s (40 ℃) are preferred kinematic viscosity, surprisingly 30~150mm ² / s (40 ℃) is more preferable that, the same as in the first grease. The urea compound is the same as the first grease. Furthermore, additives other than molybdenum disulfide and organic molybdenum compounds can be added in the same manner.

  Metal soap functions as a metal surface protectant, among which lithium stearate, lithium 12-hydroxystearate, calcium stearate, calcium 12-hydroxystearate, aluminum stearate, aluminum 12-hydroxystearate, barium stearate, 12 -Barium hydroxystearate, sodium stearate, sodium 12-hydroxyxtearate, etc. are preferable, and lithium stearate is particularly preferable because of its excellent friction coefficient reducing effect.

  The addition amount of the metal soap is preferably 3 to 10% by mass of the total amount of grease, and more preferably 5 to 10% by mass. If the amount added is less than 3% by mass, the effect on frictional wear is low.

  Hereinafter, the present invention will be further described with reference to test examples, but the present invention is not limited thereto. The added amount is a value relative to the total amount of grease.

(Test-1: Verification of first grease)
Test greases were prepared with the formulations shown in Table 1. The amount of the extreme pressure additive added was 3% by mass in Example 1 alone, and in Example 2, Example 3 and Comparative Example 2, each was equivalent to 3% by mass in total. Each test grease is used to simulate a steering mechanism and a temperature cycle is applied. The joint angle is fixed at 30 ° and torque is alternately input in a short waveform clockwise and counterclockwise. And repeatedly slid a specified number of times. The difference (increase amount) between the initial play amount of the telescopic shaft at that time and the play amount after the test was obtained, and a case where the increase amount exceeded a certain value was rejected. The result is shown in the column of the abrasion test in Table 1, and “x” is given to the failure, and “◯” is given to the pass.

  In addition, using the test grease, the joint angle was fixed at 30 ° to the same steering mechanism, torque was input in the rotational direction, and sliding was repeated. And the presence or absence of generation | occurrence | production of a stick slip was evaluated by measuring the acceleration of an outer diameter part of an expansion-contraction shaft. The results are shown in the column of stick-slip test in Table 1. “Yes” is given when stick-slip occurs, and “No” is given when no stick-slip occurs.

  From the above test results, it can be seen that, according to the present invention, encapsulating grease containing a diurea compound as a thickening agent and adding molybdenum disulfide or an organic molybdenum compound increases wear resistance and suppresses the occurrence of stick-slip. .

(Test-2: Verification of second grease)
Test greases were prepared with the formulations shown in Table 2. Then, the presence or absence of stick-slip was evaluated in the same manner as in Test-1. The results are shown in Table 2.

  From the above test results, it can be seen that stick slip generation can be suppressed by enclosing grease containing 3 to 10% by weight of metal soap and a diurea compound as a thickener according to the present invention.

(Test-3: Verification of urea compounds)
Test greases were prepared with the formulations shown in Table 3. In addition, 1 mass% of dialkyldiphenylamine (antioxidant), 1 mass of calcium sulfonate (rust inhibitor), and 2 mass% of molybdenum disulfide (extreme pressure additive) were added to each test grease. And the abrasion test was done like test-1. The results are shown in Table 3.

  From the above test results, it is understood that the wear resistance is increased by using the diurea compound represented by the general formula [I] as a thickener according to the present invention.

It is a side view of the steering mechanism part of the automobile to which the telescopic shaft of the present invention is applied. It is a longitudinal cross-sectional view which shows an example of an expansion-contraction shaft in a lower steering shaft part and an upper steering shaft part. It is a cross-sectional view along the female shaft end of the telescopic shaft shown in FIG. It is a longitudinal cross-sectional view which shows the other example of an expansion-contraction axis. It is AA sectional drawing of FIG. It is a longitudinal cross-sectional view which shows another example of an expansion-contraction axis. It is XX sectional drawing of FIG.

Explanation of symbols

5, 41, 61 Male shaft 6, 42, 62 Female shaft 20 Spline sliding portion 46 Expanding member 47 Adjustment screw 63, 65 Axial groove 67 Spherical body 69 Leaf spring 104 Steering shaft 107 Lower steering shaft portion (extensible shaft)
120 Upper steering shaft

Claims (3)

Incorporated into the steering shaft of the vehicle, the male shaft and the female shaft are fitted in a non-rotatable and slidable manner, and the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft are in contact with each other when rotating. In the telescopic shaft that transmits torque,
The gap between the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft is filled with grease containing a urea compound as a thickener and containing at least one of molybdenum disulfide and an organic molybdenum compound. Telescopic shaft. Incorporated into the steering shaft of the vehicle, the male shaft and the female shaft are fitted in a non-rotatable and slidable manner, and the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft are in contact with each other when rotating. In the telescopic shaft that transmits torque,
A grease containing a urea compound as a thickening agent and metal soap in a proportion of 3 to 10% by mass of the total amount of grease is sealed in a gap between the outer peripheral portion of the male shaft and the inner peripheral portion of the female shaft. The telescopic axis. The telescopic shaft according to claim 1 or 2, wherein the urea compound is a urea compound represented by the following general formula [I].

_(Wherein, R 1, _{R 3} is more than 50 mole% of the sum of _{R 1} and _{R 3} is an alicyclic aliphatic hydrocarbon and an aromatic hydrocarbon group, _{R 2} is an aromatic 6 to 15 carbon atoms It is a trivalent hydrogen group.)

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