Bearings – Linear bearing – Recirculating
Reexamination Certificate
1999-06-29
2001-03-20
Marmor, Charles A (Department: 3681)
Bearings
Linear bearing
Recirculating
C384S013000
Reexamination Certificate
active
06203199
ABSTRACT:
BACKGROUND
The present invention relates to a linear guide device, comprising a guide rail having a longitudinal axis, at least one guide carriage guided on the guide rail in the direction of the longitudinal axis by means of at least one rolling member loop circulating in a circulation space of the guide carriage, said rolling member loop including a bearing row of rolling members in simultaneous engagement with a bearing track of the guide rail and a bearing track of the guide carriage, a further returning row of rolling members and two arcuate rows of rolling members, said guide carriage comprising a carriage main body in the longitudinal region of the bearing row of rolling members and end units at the axially spaced ends of the carriage main body, reversing guides for the arcuate rows of rolling members being formed at least partly on the end units, a lubricant demand existing on at least a part of the roll surfaces of the linear guide device and a lubricant path system being provided in the guide carriage for satisfying said lubricant demand, said lubricant path system extending from a lubricant supply space of the guide carriage to roll surfaces, said lubricant path system being accommodated at least in part in a boundary region between at least one end unit and the carriage main body.
Such linear guide devices are known from EP 0 211 243 A2, U.S. Pat. No. 4,850,720, DE 42 10 299 C2 and DE 44 24 795 A1. In these known embodiments, the lubricant path system comprises in its end portion close to the rolling members a lubricant channel within a radially inner reversing member of a reversing guide. This lubricant channel terminates into a reversing surface of the reversing member and thus into the circulation space of the rolling members.
According to U.S. Pat. No. 4,850,720, the outlet opening of the lubricant channel extending within the radially inner reversing member is formed as a throttle valve in the form of a narrow-sized bore which extends from the lubricant channel in radial direction to the radially inner reversing surface of the reversing member.
According to DE 42 10 299 C2, at the outlet zone of the lubricant channel into the radially inner reversing surface relief pressure valves are provided which open as the lubricant pressure is increased but prevent lubricant from flowing off under the influence of gravity. This embodiment is said to be especially suited if low-viscosity oil is used as the lubricant. According to this embodiment, the relief pressure valves are provided directly at the outlet into the circulation space of the rolling members, i.e. at the radially inner reversing surface of the reversing member.
According to DE 44 24 795 A1 the lubricant oil flows out into the circulation space of the rolling members through outlet channels of the radially inner reversing member, which outlet channels terminate into the radially inner reversing surface of the reversing member. These outlet channels begin within a common throttle chamber which receives a foam material strip. Upon transmission of a lubricant oil pulse, the oil penetrates the open-cell foam material which serves as a throttle means. The foam material has no contact with the rolling members. After having penetrated the foam material, the lubricant oil flows through the outlet channels from the throttle chamber into the circulation space, as a consequence of a pressure pulse. The foam material strip prevents oil from flowing out into the circulation space if no pressure pulse has been applied. With this embodiment, it is not excluded that, caused by one or a plurality of consecutive pressure pulses, too much oil gets into the circulation space. There is the that lubricant oil might flow out into the ambient if the circulation space has not been made oil-tight. On the other hand, there will also be the danger that too little lubricant oil is availabe for the circulating rolling members if the lubricant oil contained in the circulation space has been consumed prematurely between two consecutive pressure pulses. The technical problem underlying the present invention is to take care in case of the use of lubricant oil that sufficient lubricant oil is always and over a long period of time available in the circulation space and to simultaneously take care that no lubricant oil quantities beyond the respective lubricant demand get into and possibly out of the circulation space.
SUMMARY
The present invention suggests as solution to this technical problem that a lubricant oil supply line, which is connected to the lubricant supply space and, which extends at least in part in the boundary region approximately in circumferential direction of the guide rail, be formed at least along a part of its length of a lubricant oil supply capillary line which supplies lubricant oil irrespective of the existence of a pressure difference, said lubricant oil supply capillary line being in licking contact in at least one licking region with rolling members of said at least one rolling member loop or with the bearing track of the guide rail.
When speaking of a lubricant supply space, the volume and the shape of the lubricant supply space is completely left out of account. The lubricant supply space may consist of one or of a plurality of chambers, but it may also be simply formed of an upstream part of the lubricant path system. Furthermore, there should not exist any restrictions as to the manner of lubricant fill and refill. It is possible to periodically fill lubricant oil into the lubricant supply space, possibly through a grease nipple designed as a check valve. It is also possible to have a life-long charge filled into the lubricant supply space before use on the manufacturer side or on the user side.
According to the solution suggested by the present invention, the rolling members lick the lubricant oil from the lubricant oil supply capillary line in the respective licking region when the rolling members roll along this licking region. According to an alternative suggestion, the lubricant oil is licked from the lubricant oil supply capillary line in the respective licking region by the track of the guide rail when the guide carriage moves along the guide rail. In any case, lubricant oil can get to the rolling members or to the track of the guide rail, respectively, always and only if there is a relative movement between the licking region of the lubricant oil supply capillary line, on the one hand, and the rolling members or the bearing track of the guide rail, on the other hand. Either on account of its great lubricant-saturated volume or on account of its communication with free lubricant oil within the lubricant supply space, the lubricant oil supply capillary line is suited to safeguard long-term lubrication of the rolling members or of the bearing track of the guide rail, respectively, to the required extent. Of course, when constructing the linear guide device, one will have to take care by the setting of various parameters, such as the permeability of the lubricant oil supply capillary line, the cross-section of this capillary line, the viscosity of the lubricant oil and the dimensions of the contact region between the capillary line and the rolling members or the bearing track of the guide rail, that sufficient lubrication is guaranteed during operation. The risk of overfilling of the circulation space with lubricant oil, which might cause undesired outflow of lubricant oil from the circulation space, does not exist with this suggestion of the invention. In contrast to the known valve solutions, the feeding action of the lubricant oil supply capillary line is not based upon a pressure difference but upon an oil saturation gradient within the capillary material. This saturation gradient is caused by the fact that oil is removed within the licking region from the lubricant oil supply capillary line and the thus caused oil impoverishment within the licking region is continuously compensated by oil coming from the lubricant supply space. As the oil supply is thus principally independent from the oil pressure,
Baker & Botts L.L.P.
Deutsche Star GmbH
Marmor Charles A
Pang Roger
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