The present application claims priority under 35 U.S.C xc2xa7119 to Japanese Patent Application No.2000-073932 filed Mar. 13, 2000 entitled xe2x80x9cROLLING GUIDE DEVICE xe2x80x9d, No.2000-367605 filed Dec. 1, 2000 entitled xe2x80x9cROLLING GUIDE DEVICE AND DRIVE SYSTEM USING ROLLING GUIDE DEVICExe2x80x9d, and No.2001-037486 filed Feb. 14, 2001 entitled xe2x80x9cROLLING GUIDE DEVICE AND DRIVE SYSTEM USING ROLLING GUIDE DEVICExe2x80x9d. The contents of that application are incorporated herein by reference in their entirety.
1. Field of the Invention
The present invention relates to a rolling guide device in which a movable rail is made slidable with respect to a track rail and also relates to a drive system using such a rolling guide device.
2. Description of the Related Art
As a rolling guide device in which a movable rail is made slidable with respect to a track rail, there has been known a slide rail such as shown in FIG. 25 (see Japanese Utility Model Publication No. SHO 62-8765). Such slide rail comprises a track rail member 1 having an opened recess 1a (i.e. having substantially -shaped (box-shaped) cross section) formed by both inner side surfaces 1b, 1b and a bottom surface 1c and a movable rail member 2 which is supported between both the inner side surfaces 1b, 1b of the track rail member 1 to be movable in the longitudinal direction thereof. The movable rail member 2 also has an opened recess 2a (i.e. having substantially -shaped (box-shaped) cross section).
The track rail member 1 and the movable rail member 2 have substantially the same longitudinal length. The inner side surfaces 1b of the track rail member 1 are formed with ball rolling grooves, respectively, along which balls roll in the longitudinal direction thereof, and outer side surfaces 2b of the movable rail member 2 are also formed with loaded ball rolling grooves, respectively, so as to extend in the longitudinal direction thereof and to oppose the ball rolling grooves formed to the track rail member 1.
A number of balls 3 are arranged and housed between these ball rolling grooves and loaded ball rolling grooves, and these balls 3 are held by a cage 4 to be rotatable and slidable. When the movable rail member 2 slides with respect to the track rail member 1 in the longitudinal direction thereof, these balls 3 roll and, hence, the slide rail becomes smoothly expandable or contractive.
Further, though not shown, there is also known a cam-follower type drawer device of a structure that is movable and track rails are both provided with wheels so that the movable rail is drawn with respect to the track rail, as a rolling guide device in which a movable rail is slidable with respect to a track rail.
However, in the conventional slide rail such as mentioned above, a number of balls 3 disposed and arranged between the track rail member 1 and the movable rail member 2 do not completely perform the rolling motion and will roll with a slight sliding motion. In the conventional slide rail, because the balls 3 do not circulate and only reciprocally move along the loaded rolling passage between the ball rolling grooves and the loaded ball rolling grooves, if the balls 3 slide, the cage 4 supporting (bearing) the balls 3 would be displaced from the initial position. As a result, in spite of the fact that an effective stroke of the movable rail member 2 is not achieved, the cage 4 collides with a stopper 5 of the track rail member 1 and, hence, such effective stroke could not be obtained. In this case, when it is required to slide the movable rail member 2 with the cage 4 colliding with the stopper 5, the movable rail member 2 will slide with the balls 3 being slipped, and accordingly, a large force is required to move the movable rail member 2.
Furthermore, in the conventional structure of the slide rail, in order to obtain a large stroke of the movable rail member 2, it is necessary for the movable rail member 2 to once come off from a portion at which the balls 3 exist and then to be engaged with that portion at which the balls 3 exist. That is, in the case where the movable rail member 2 comes off from the portion at which the balls 3 exist, for example, the movable rail member 2 which has been loaded with ten (10) balls 3 is loaded with, for example, six (6) balls 3, and hence the ability for bearing moment load, radial load and thrust load is deteriorated.
Moreover, with the cam-follower type drawer device, because the wheels generally have backlash or looseness, the movable rail member 2 does not smoothly slide, and furthermore, because the wheel has a cylindrical structure, a direction along which a load is received is determined, and hence, the thrust load cannot be received.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a rolling guide device capable of taking a large expansion/contraction stroke and sufficiently bearing moment load, radial load and thrust load at any expanded (contracted) attitude and also provide a drive system incorporated with such a rolling guide device.
This and other objects can be achieved according to the present invention by providing, in one aspect, a rolling guide device comprising:
a track rail formed with a rolling member rolling surface extending along a longitudinal direction thereof;
a movable rail formed with a loaded rolling member rolling surface extending along a longitudinal direction thereof so as to oppose the rolling member rolling surface of the track rail;
a track rail side rolling member circulation passage formed to the track rail so as to circulate the rolling members rolling between the track rail and the movable rail;
a movable rail side rolling member circulation passage formed to the movable rail so as to circulate the rolling members rolling between the track rail and the movable rail; and a number of rolling members disposed and arranged in the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage.
According to this aspect, when the movable rail slides with respect to the track rail, the rolling members arranged between the track rail and the movable rail endlessly circulate in the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage while rolling therealong. As mentioned, because the rolling members circulate in the endless manner, even if the rolling member slides during the rolling motion, there is no causing of a case that a cage is shifted from the initial position as in the conventional structure, and hence, a large expansion (contraction) stroke is obtainable. Furthermore, in an optional expanded (contracted) attitude, there remains a considerable distance between the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage, so that a rolling guide device, which can bear even the moment load, can be realized.
Further, when the movable rail slides and its stroke is made large, the considerable distance corresponding to this stroke is made short and the capability of bearing the moment load is reduced. However, according to the present invention, the movable rail does not come off from the balls, so that the capability of bearing the moment load is not extremely reduced. Moreover, because the movable rail does not come off from the balls and the number of the rolling members supported at an optional expansion (contraction) attitude is not changed, in contrast to the conventional slide rail, there can be provided a rolling guide device bearing the constant radial load and thrust load.
In the above aspect, the following preferred embodiments or examples may be provided with advantageous functions and effects thereof.
The track rail side rolling member circulation passage is formed in one longitudinal end side of the track rail and the movable rail side rolling member circulation passage is formed in one longitudinal end side, opposing that one end side of the track rail, of the movable rail.
Accordingly, the distance between the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage can be made large, so that a rolling guide device bearing the large moment load can be provided.
Furthermore, the track rail has an opened recess having a-shaped section and has inside surfaces to which the rolling member rolling surfaces are formed, the movable rail is fitted into the recess of the track rail, and the movable rail has outside surfaces to which the loaded rolling member rolling surfaces are formed so as to oppose the rolling member rolling surfaces formed to the track rail inside surfaces.
Thus, various kinds of loads including radial load, thrust load and moment load can be supported in a balanced condition.
The track rail side rolling member circulation passage is provided with a rolling member return passage substantially parallel to the rolling member rolling surface and a rolling direction changing passage communicating the rolling member rolling surface and the rolling member return passage, the movable rail side rolling member circulation passage is provided with a rolling member return passage substantially parallel to the loaded rolling member rolling surface and a rolling direction changing passage communicating the rolling member rolling surface and the rolling member return passage, the rolling direction changing passages of the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage are formed to a deflector which is formed independently from a track rail body and a movable rail body, and the deflector is fitted to holes formed in the track rail body and movable rail body from the side portions thereof.
According to this embodiment, the rolling direction changing passages can be easily formed in the long track rail and movable rail.
The return passages are drilled in the track rail body and the movable rail body from the longitudinal end portions thereof.
According to this embodiment, the return passages can be easily formed in the long track rail and movable rail.
The deflector is composed of a plurality of sections splitting along the rolling direction changing passages.
Accordingly, the rolling direction changing passages having a complicated structure may be easily formed in the deflector.
The deflector is made of a synthetic resin.
Accordingly, the rolling direction changing passages having a complicated structure may be easily formed in the deflector, and moreover, noise which may be generated when the rolling members roll in the rolling direction changing passages will be suppressed.
The above mentioned object of the present invention can be also achieved by providing, in another aspect, a drive system comprising:
a track rail formed with a rolling member rolling surface extending along a longitudinal direction thereof;
a movable rail formed with a loaded rolling member rolling surface extending along a longitudinal direction thereof so as to oppose the rolling member rolling surface of the track rail;
a track rail side rolling member circulation passage formed on the track rail so as to circulate the rolling members rolling between the track rail and the movable rail;
a movable rail side rolling member circulation passage formed on the movable rail so as to circulate the rolling members rolling between the track rail and the movable rail;
a number of rolling members disposed and arranged in the track rail side rolling member circulation passage and the movable rail side rolling member circulation passage; and
a linear motor means having a primary side mounted to either one of the track rail and the movable rail and a secondary side mounted to another one of the track rail and the movable rail.
According this aspect, the expansion (contraction) stroke can be made large and the moment load, the radial load and the thrust load can be sufficiently supported at an optional attitude of the system. Furthermore, because the linear motors are incorporated between the track rail and the movable rail, the use of the ball screw or like can be eliminated, thus moving the movable rail at high speed with less noise. Moreover, because it is not necessary to provide a space for a rotary motor, the drive system can be made thin and compact.
According to preferred embodiments or examples of this aspect, the following advantageous functions and effects may be attained.
The track rail side rolling member circulation passage is formed in one longitudinal end side of the track rail and the movable rail side rolling member circulation passage is formed in one longitudinal end side, opposing that one end side of the track rail, of the movable rail, and the linear motor means comprises first and second linear motors, the first linear motor having a primary side mounted to a portion near the track rail side rolling member circulation passage of the track rail, the second linear motor having a secondary side mounted to the track rail along the longitudinal direction thereof so as to be continuous to the primary side of the first linear motor, and the second linear motor having a primary side mounted to a portion near the movable rail side rolling member circulation passage of the movable rail, the first linear motor having a secondary side mounted to the movable rail along the longitudinal direction thereof so as to be continuous to the primary side of the second linear motor.
According to this embodiment, because two sets of linear motors are incorporated in the drive system, the thrust force can be made two times (twice), and the excitation is averaged to thereby make smooth the movement of the movable rail. Furthermore, the first linear motor has a primary side mounted to a portion near the track rail side rolling member circulation passage of the track rail and the second linear motor has a primary side mounted to a portion near the movable rail side rolling member circulation passage of the movable rail, so that the thrust force can be generated at substantially the same positions of the movable side rolling member circulation passage and the track rail side rolling member circulation passage, regardless of the stroke of the movable rail. Therefore, even if a pitching or yawing moment is applied to the movable rail, the thrust force can be stably applied to the movable rail.
The first and second linear motors may be composed of linear induction motors or linear pulse motors such that the secondary sides thereof are opposed to each other.
For example, in a case where linear D.C. motors are used, two sets of linear motors are disposed in back-to-back arrangement and a distance between the secondary side magnets is short, an alternating magnetic field may be generated between the magnets. However, according to this embodiment of the present invention, because the linear induction motors or linear pulse motors are used without using the magnets, there is no fear of causing any alternating magnetic filed. However, a linear D.C. motor may be utilized as far as a relatively large distance between the secondary sides of the linear D.C. motors can be taken so as not to influence from each other.
The nature and further characteristic features of the present invention may be made clear from the following descriptions made with reference to the accompanying drawings.