Bearings – Linear bearing – Combined with seal or guard
Patent
1998-10-11
2000-02-29
Hannon, Thomas R.
Bearings
Linear bearing
Combined with seal or guard
384 45, F16C 2906
Patent
active
060301244
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Field of the Invention
The invention concerns a linear rolling bearing comprising a fixed guide rail and a guide carriage which has a U-shaped cross-section and partially surrounds the guide rail, said guide carriage being slidably mounted on the guide rail while being constituted by a carrier body on whose ends pointing in directions of movement, there are arranged head pieces acting as deflectors for rolling elements and comprising end wipers in contact with the guide rail contour, longitudinal wipers which act as seals and have sealing lips which bear against the guide rail being arranged between the guide carriage and the guide rail.
2. Background of the Invention
In the case of profiled rail guides, the penetration of dirt particles into the bearing region must be prevented in order to maintain the functioning ability of the bearing and this should be accomplished in the smallest possible design space. It is particularly important to prevent dirt particles which have entered the guide despite the end wipers from moving further on to the raceways and into the ball circuits. Damage to the lip of the end wipers can be caused at sharp-edged bores of the guide rail due to a sinking of covering caps or due to improper mounting. Chamfered guide rail bores allow dirt particles to enter the bearing region in spite of the end wipers.
A linear bearing having longitudinal wipers which prevent the penetration of dirt under the guide carriage is known from EP-OS 0 594 209. However, with such a longitudinal seal, there exists the problem that the seal can sag across the length of the carrier body so that dirt can still penetrate into the bearing region. The longitudinal seal is often unstable because it is only made of an elastic plastic. In this prior art, the longitudinal seal is therefore fixed on a rolling element retention web which is screwed to the carrier body by a number of screws. It is further known from EP-OS 0 427 238 to arrange lower longitudinal seals or longitudinal wipers in recesses or depressions of the carrier body with their sealing lips bearing against the guide rail.
A linear rolling bearing of the initially cited type is shown in DE-OS 44 13 373. On each side of the guide rail, the carrier body comprises a detachable carrier body bottom portion which, to assure sealing, requires two longitudinal sealing strips comprising sealing lips.
DE-GM 93 11 059 shows a linear rolling bearing in which sealing lips which prevent the exit of lubricant out of the rolling element region are arranged above the upper rolling element row and under the lower rolling element row on each side of the guide rail between the carrier body and the guide rail. These longitudinal seals are disposed in grooves of the carrier body. The drawback of this, however, is that, due to the grooves in the carrier body, notch effects occur which can have an unfavorable influence.
SUMMARY OF THE INVENTION
The object of the invention is to improve the functioning ability of the linear rolling bearing and reduce the required design space while preventing the occurrence of detrimental notch effects on the carrier body.
This object is achieved according to the invention by the fact that an additional sealing lip is formed on each longitudinal wiper and bears against the carrier body. A reinforcing wire extending over the entire length of the longitudinal wiper can be embedded in each longitudinal wiper. The longitudinal wiper of the invention, for example when used as an upper longitudinal wiper, therefore has two sealing lips: an upper sealing lip which seals against the carrier body of the guide carriage and a lower sealing lip which seals against an upper sealing surface of the guide rail. By this, a penetration of dirt into the bearing region is prevented even in the presence of slight sags of the longitudinal wiper without having to make cost-intensive grooves in the carrier body. The longitudinal wiper is designed so that both the sealing lips are under pre-tension in the installed state.
The longitudinal wiper c
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patent: 5429439 (1995-07-01), Hsu et al.
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patent: 5492412 (1996-02-01), Tsukada
Moseberg Ralf
Scheib Frank
Welsch Annette
Hannon Thomas R.
Ina Walzlager Schaeffler OHG
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