ROLLING DEVICE EMPLOYING LUBRICATING GREASE COMPOSITION AND ELECTRIC POWER STEERING APPARATUS EMPLOYING THE ROLLING DEVICE
申请人:JTEKT Corporation
公开号:EP1889897A1
公开(公告)日:2008-02-20
A rolling device is provided which employs a lubricating grease composition which considerably diminishes irregular friction fluctuations occurring on rolling/sliding friction surfaces, shows stable low-torque characteristics in a wide temperature range, can retain a sufficient oil film even at high temperatures, has a long life, and contains a novel thickener. Also provided is an electric power steering apparatus employing the rolling device.
The rolling device is characterized by employing a lubricating grease composition comprising: a thickener which is a mixed thickener comprising a mixture of (a) one or more diurea compounds which are one or more aliphatic diurea compounds having an average molecular weight of 500-750 in which 10-70% by mole of the linear hydrocarbon groups are unsaturated components, the aliphatic diurea compounds having been produced using as a raw material one or more primary amines having a total amine value in the range of 200-400, (b) at least one fatty acid metal salt, and (c) at least one amide compound selected from the group consisting of aliphatic amides and aliphatic bisamides represented by formulae (I) and (II):
R1CONH2 (I)
R1CONHR2NHCOR1 (II)
(wherein R1 represents a saturated or unsaturated alkyl group having 15-17 carbon atoms and R2 represents a methylene group or an ethylene group), the proportions of (a) and of (b) and (c) satisfying the relationship: a/b+c=0.2-10
provided that
(1) the proportion of ingredient (a) is 1-10,
(2) the proportion of ingredient (b) is 0.5-2.5, and
(3) the proportion of ingredient (c) is 0.5-2.5, the amount of the thickener being 2-30% by weight, based on the whole composition;
(d) a base oil which is a lube base oil having a pour point of -25°C or lower and comprising a synthetic hydrocarbon oil as the main component; and (e) an additive which is a mixture comprising an organomolybdenum complex, an organozinc compound of a dithiocarbamic acid, and an organozinc compound of dithiophosphoric acid, the amount of the additive being 1-7% by weight, based on the whole composition.
本发明提供了一种滚动装置,该装置采用了一种润滑脂组合物,可显著减少滚动/滑动摩擦面上出现的不规则摩擦波动,在宽温度范围内显示出稳定的低扭矩特性,即使在高温下也能保持足够的油膜,具有较长的使用寿命,并且含有一种新型增稠剂。此外,还提供了一种采用该滚动装置的电动助力转向装置。
该滚动装置的特点是采用了一种润滑脂组合物,其中包括一种稠化剂,它是一种混合稠化剂,包括以下物质的混合物 (a) 一种或多种二脲化合物,它是一种或多种脂肪族二脲化合物,平均分子量为 500-750,其中 10-70%(摩尔)的线性烃基为不饱和组分、(b) 至少一种脂肪酸金属盐,以及 (c) 至少一种酰胺化合物,选自由式 (I) 和 (II) 所代表的脂肪族酰胺和脂肪族双酰胺组成的组:
R1CONH2 (I)
R1CONHR2NHCOR1 (II)
(其中 R1 代表具有 15-17 个碳原子的饱和或不饱和烷基,R2 代表亚甲基或亚乙 烯基),(a)和(b)及(c)的比例满足以下关系:a/b+c=0.2-10
条件是
(1) 成分(a)的比例为 1-10、
(2) 成分(b)的比例为 0.5-2.5,以及
(3) 成分(c)的比例为 0.5-2.5,增稠剂的用量为整个组合物重量的 2-30%;
(d) 基础油,即倾点为-25°C 或更低的润滑油基础油,其主要成分为合成烃油; (e) 添加剂,即由有机钼络合物、二硫代氨基甲酸的有机锌化合物和二硫代磷酸的 有机锌化合物组成的混合物,添加剂的用量为整个组合物重量的 1-7%。