JP2010159840A - Ball spline - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball spline capable of smoothing a stroke of a spline. <P>SOLUTION: A retainer body 19 and a retainer lid 20 are abutted with each other, and supported in an outer cylinder body 17 by a pair of stopper rings 21, 22 arranged on both the end surfaces. Each stopper ring 21, 22 is formed as a corrugated washer, that is, a kind of a spring washer. Thereby, the retainer body 19 and the retainer lid 20 are assembled by applying an elastic axial preload. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a ball spline, and more particularly, to a ball spline used under conditions that are susceptible to excessive torque.

  Ball splines are often used for electric actuators and shock absorbers in combination with ball screws. For example, in Patent Document 1, a ball screw nut rotates by connecting a motor to the ball screw nut. It is disclosed that a ball screw having a configuration in which a screw shaft extending vertically moves linearly in an axial direction is applied to a shock absorber.

  An example of an outer cylinder used in a conventional ball spline is shown in FIGS. In the figure, the ball spline includes a shaft (35) provided with a spline track (35a), a ball spline outer cylinder (31) fitted on the shaft (35), a ball spline outer cylinder (31) and a shaft ( 35), and the ball spline outer cylinder (31) is opposed to the spline raceway (35a) of the shaft (35) so that the main passageway (36) A substantially cylindrical metal outer cylinder main body (32) in which a spline track (32a) forming an inner surface is formed, and a return passage (33a) is formed and fitted to the inner periphery of the outer cylinder main body (32). The cage main body (33a) is formed with a substantially cylindrical synthetic resin cage body (33) and a communication passage (34a) communicating the return passage (33a) of the cage body (33) and the main passage (36). (33) has a synthetic resin cage lid (34) abutted from one end side.

  As the shaft (35) moves linearly, the ball (37) circulates in the main passage (36), the return passage (33a) of the cage body (33), and the communication passage (34a) of the cage lid (34). And since this circulation is performed smoothly, the smooth stroke of a spline is ensured.

JP 2005-264992 A

  In the ball spline outer cylinder (31), there is a minute gap G at the abutting portion between the cage main body (33) and the cage lid (34). May cause poor circulation such as increased sliding resistance, which may hinder the stroke of the spline.

  That is, in FIG. 6, if the shaft (35) moves to the left, the ball spline outer cylinder (31) tries to move to the right in the drawing, and the shaft (35) moves linearly. Along with this, the ball (37) in the main passage (36) is pushed out to the return passage (33a) of the cage body (33) and the ball (37) in the communication passage (34a) of the cage lid (34). ) Is returned to the main passageway (36). When the ball (37) indicated by A enters the main passage (36) from the return passage (33a), the ball (37) indicated by B pushes the retainer lid (34) to the right indicated by the arrow, and the return passage ( The width P of 33a) increases, and the ball (37) indicated by B may be caught at the entrance of the main passage (36). In this case, the trajectory of the turning of the ball (37) is shifted, the ball (37) is filled in the return passage (33a), the ball (37) in the main passage (36) does not enter the return passage (33a), There arises a problem that the sliding resistance of the ball spline is increased and the stroke of the spline is not smooth.

  An object of the present invention is to provide a ball spline that can smooth the stroke of the spline.

  A ball spline according to the present invention includes a shaft provided with a spline track, and a ball spline outer tube fitted to the shaft via a ball. The ball spline outer tube is mainly disposed by being opposed to the spline track of the shaft. A substantially cylindrical outer cylinder main body formed with a spline track constituting a passage; a substantially cylindrical cage main body formed with a return passage and fitted to the inner periphery of the outer cylinder main body; In the ball spline in which a communication passage that connects the return passage and the main passage is formed and has a retainer lid that is abutted to the retainer body from one end side, the retainer body and the retainer lid have a shaft It is characterized by being assembled with an elastic pressure applied in the direction.

  The ball rolls between the spline raceway formed on the shaft and the spline raceway formed on the ball spline outer cylinder (main passage), and again through the return passage of the cage body and the communication passage of the cage lid, Return to the main passage (circulate).

  The cage body and the cage lid are abutted against each other and supported by the outer cylinder body by a pair of retaining rings disposed on both end faces thereof. The cage body and the cage lid are made of synthetic resin.

  In order to smoothen the ball circulation in the spline outer cylinder and eliminate the clogging of the balls, it is only necessary to prevent the gap between the butt and the retainer body and the retainer lid from opening. This gap is set to zero. However, if the gap is 0 (no clearance), a large force acts on the abutting portion between the cage body and the cage lid due to temperature changes and dimensional variations, and the cage may be deformed, resulting in poor circulation. The pressurization is formed by an elastic force so that excessive pressurization does not occur.

  In order to achieve elastic pressurization, the retaining ring may be easily elastically deformed, or the cage body and / or cage lid may be elastically deformed.

  As a configuration in which the retaining ring elastically deforms, for example, the retainer body and the retainer lid are abutted against each other and supported by the outer cylinder body by a pair of retaining rings disposed on both end faces thereof. At least one of the retaining rings may be a spring washer. For example, a wave washer is used as the spring washer.

  As a configuration in which the cage body and / or the cage lid are elastically deformed, for example, the cage body and the cage lid are abutted against each other, and the outer cylinder is formed by a pair of C-shaped retaining rings disposed on both end faces thereof. It is supported by the main body, and at least one of the end face of the cage main body and the end face of the cage lid may be formed with three or more convex portions protruding in the circumferential direction at predetermined intervals. In this case, it is more preferable that a hole that facilitates deformation of the convex portion inward in the axial direction is formed at the end of the cage main body and the cage lid on which the convex portion is formed.

  The structure for elastically deforming the retaining ring, the retainer body and the retainer lid is not limited to the above, and in any case, the retainer body and the retainer lid are applied with an elastic pressure in the axial direction. As a result, the spline stroke becomes smooth, and effects such as a reduction in sliding noise, a feeling of catching, and a loss reduction can be obtained.

  Spline trajectories that receive clockwise rotation and counterclockwise rotation are paired, and a plurality of pairs (for example, three pairs) are provided. For example, a plurality of (for example, three) ball receiving portions formed so as to protrude from the reference cylindrical surface are provided on the outer periphery of the shaft, and spline is respectively provided on the clockwise side and the counterclockwise side of the ball receiving portion. A trajectory is formed. Correspondingly, on the inner periphery of the outer cylinder body, a spline track that faces the clockwise spline track of the ball receiving portion from the clockwise direction and a counterclockwise spline track of the ball receiving portion counterclockwise. Spline tracks facing each other from the direction side are formed.

  The ball spline is preferably combined with a ball screw, a screw shaft provided with a ball screw raceway and an axially extending spline raceway, and a rotatable ball screwed to the ball screw raceway of the screw shaft via the ball. A screw nut and a ball spline outer tube that is fitted to the spline track via a ball and guides the axial linear motion of the screw shaft are included.

  In such a ball screw with a ball spline, the ball spline has a ball spline outer cylinder that is prevented from rotating with respect to the housing by a key or other non-rotating portion to prevent rotation of the screw shaft, and torque generated by the ball screw nut. Receive the reaction force.

  The screw shaft, ball screw nut, and ball spline outer cylinder main body are made of carbon steel such as S45C and S55C or SAE4150 steel, and the ball is made of bearing steel (SUJ2), for example.

  The ball spline according to the present invention may be used in combination with a ball screw as an actuator (a configuration in which a ball screw nut is rotated by a motor, whereby the screw shaft moves linearly), and a shock absorber (screw shaft). Is moved linearly by an external force, whereby the ball screw nut is rotated and the electromagnetic force generated by the motor is used as a damping force.

  When used in an actuator or shock absorber, for example, a ball screw with a ball spline, a hollow shaft integrated with a ball screw nut, a hollow shaft rotatably supported via a bearing and a ball spline outer cylinder And a motor composed of a motor rotor fixed to the hollow shaft and a motor stator fixed to the inner diameter of the housing.

  The screw shaft reciprocates linearly and is usually provided with a stopper for preventing movement beyond a predetermined amount. The stopper can be formed, for example, by providing the screw shaft with a flange portion that contacts the housing when the screw shaft moves by a predetermined amount or more, and the stopper is formed on a member that moves linearly integrally with the screw shaft. Alternatively, it may be provided on a member that does not move linearly (a housing or a hollow shaft).

  According to the ball spline of the present invention, the cage main body and the cage lid are assembled with an axial elastic pressure applied, so that the stroke of the spline is smoothed, the sliding noise is reduced, and the catch is caught. Effects such as reduction of feeling and loss can be obtained.

FIG. 1 is a longitudinal sectional view showing a ball screw device using a ball spline according to the present invention. FIG. 2 is a partially cutaway side view showing a first embodiment of the ball spline according to the present invention. FIG. 3 is a perspective view showing a corrugated washer used in the first embodiment. FIG. 4 is a partially cutaway side view showing a second embodiment of the ball spline according to the present invention. FIG. 5 is a perspective view showing the cage of the second embodiment. FIG. 6 is a side view of the conventional ball spline outer cylinder with the outer cylinder body removed. FIG. 7 is a cross-sectional view of the same.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the top and bottom refer to the top and bottom of FIG.

  FIG. 1 shows a ball screw device with a motor using a ball spline according to the present invention.

  The motorized ball screw device (1) consists of a ball screw raceway (2a) and a vertically extending steel screw shaft (2) provided with a spline raceway (2b), and a ball screw of the screw shaft (2). A rotatable steel ball screw nut (3) screwed to the raceway (2a) via a ball, and a screw shaft fitted to the spline raceway (2b) via a ball on the lower end side of the screw shaft (2). The ball spline outer cylinder (4) that guides the vertical movement (axial direction) of (2), the hollow shaft (5) that is integrated with the ball screw nut (3), and the bearing (7) Through which the hollow shaft (5) is rotatably supported and the ball spline outer cylinder (4) is supported, a cylindrical motor rotor (9) fixed to the hollow shaft (5), and the housing (6 And a motor (8) comprising a cylindrical motor stator (10) fixed to the inner diameter.

  The motor (8) is a permanent magnet type three-phase synchronous motor, the motor rotor (9) is a permanent magnet, and a U-phase, V-phase and W-phase three-phase coil (10a) is provided on the motor stator (10). ) Is wound.

  The screw shaft (2) and the hollow shaft (5) are arranged concentrically, and the ball screw device (1) rotates the ball screw nut (3), the hollow shaft (5), and the motor rotor (9). Thus, the screw shaft (2) is used in the form of linear movement.

  The hollow shaft (5) has a small-diameter portion (11) for guiding the screw shaft (2), and a large diameter whose inner peripheral surface is fixed to the outer peripheral surface of the ball screw nut (3) and that holds the bearing (7) on the outer peripheral surface. It consists of a diameter part (12).

  The ball spline outer cylinder (4) is prevented from rotating with respect to the housing (6) by a detent (for example, a key) (13) to prevent the screw shaft (2) from rotating and guide its vertical movement. The

  2 and 3 show a first embodiment of the ball spline according to the present invention. In FIG. 2, the cage (18) is a diagram (side view) viewed from the outside in the radial direction. It is shown. Since the cross-sectional shape of the ball spline is the same as that of the conventional one shown in FIG. 7, its illustration is omitted.

  In FIG. 2, a ball spline outer cylinder (4) includes a substantially cylindrical metal outer cylinder body (17) and a substantially cylindrical cage (fitting and fixed to the inner periphery of the outer cylinder body (17)). 18). The cage (18) is made of a synthetic resin and includes a cage body (19) and a cage lid (20), which are abutted against each other and a pair of retaining rings (21 ) (22) is supported by the outer cylinder main body (17).

  On the outer periphery of the screw shaft (2), three ball receiving portions (15) formed so as to protrude from the reference cylindrical surface are provided at equal intervals in the circumferential direction. Spline tracks (2b) (2c) are formed on the direction shoulder and the counterclockwise shoulder, respectively.

  The outer cylinder main body (17) is formed with spline tracks (4a) and (4b) constituting the main passage (23) by being opposed to the spline tracks (2b) and (2c) of the screw shaft (2). . Thus, the spline track (2b) (4a) that loads the torque when the screw shaft (2) tries to rotate clockwise, and the torque when the screw shaft (2) tries to rotate counterclockwise. Spline tracks (2c) and (4b) are loaded in pairs, and three pairs are provided.

  The retainer (18) is formed with a return passage (24) communicating with the left and right ends of the main passage (23) between the outer cylinder body (17). Each return passage (24) is provided so as to sandwich the paired main passage (23) from both sides in the circumferential direction. The cage lid (20) is formed with an arc-shaped communication path (25) that communicates the return path (24) of the cage body (19) with the main path (23), and the cage lid (20 The return passage (24) portion other than the communication passage (25) formed in the retainer body (19) is formed in the cage body (19).

  The ball (16) is disposed in the main passage (23) and the return passage (24), and the ball (16) rolling on the main passage (23) is connected to the screw shaft (2) and the ball spline outer cylinder (4). It is designed to guide relative linear motion.

  The retaining rings (21) and (22) that support the retainer body (19) and the retainer lid (20) on the outer cylinder body (17) are not C-shaped retaining rings that are conventionally used. The wave washer (spring washer) as shown in FIG.

  The corrugated washers (21) and (22) have elasticity in a direction in which the cage main body (19) and the cage lid (20) are close to each other in the axial direction, whereby the cage main body (19) and the cage The lid (20) is assembled by applying an elastic pressure in the axial direction. As a result, it is possible to prevent a gap from occurring on the abutting surface between the cage body (19) and the cage lid (20), and the spline stroke is smooth. The corrugated washers (21) and (22) are fitted into annular grooves (17a) and (17b) formed in the outer cylinder main body (17). By adjusting the groove width of the annular grooves (17a) (17b) and the distance between the annular grooves (17a) (17b), the elastic force of the corrugated washers (21) (22) (retainer body (19) and retainer) The pressure of the lid (20) can be adjusted, and the pressure is adjusted so that the cage body (19) and cage lid (20) do not deform due to temperature changes and dimensional variations. .

  4 and 5 show a second embodiment of the ball spline according to the present invention. In FIG. 4, the cage (28) is a diagram (side view) seen from the outside in the radial direction. It is shown.

  The ball spline outer cylinder (4) of this embodiment is fitted into the substantially cylindrical metal outer cylinder main body (17) and the inner periphery of the outer cylinder main body (17), as in the first embodiment. And a fixed substantially cylindrical cage (28). The cage (28) is made of a synthetic resin and includes a cage body (29) and a cage lid (30), both of which are butted against each other and a pair of retaining rings (41) disposed on both end faces thereof. ) (42) is supported by the outer cylinder main body (17).

  In this embodiment, the retaining rings (41) and (42) are C-shaped retaining rings similar to the conventional one, and the retaining rings (41) and (42) have a function of imparting an axial elastic force. The arcuate protrusions (29a) and (30a) projecting in the axial direction are formed at three positions at predetermined intervals in the circumferential direction on the end surface of the cage body (29) and the end surface of the cage lid (30). As a result, an axial elastic pressure is applied to the cage body (29) and the cage lid (30).

  At the ends of the cage body (29) and the cage lid (30) where the projections (29a) and (30a) are formed, the projections (29a) and (30a) can be easily deformed inward in the axial direction. Through holes (29b) and (30b) are further formed. One through hole (29b) (30b) is provided corresponding to each convex part (29a) (30a).

  The configuration other than the above is the same as that of the first embodiment.

  In the second embodiment, the retainer body (29) and the retainer lid (30) are fixed to the C shape via the projecting portions (29a) (30a) projecting in the axial direction formed on the end surfaces thereof. By being sandwiched between the rings (41) and (42), an elastic pressure is applied in the axial direction and assembled. As a result, it is possible to prevent a gap from being formed on the abutting surface between the cage body (29) and the cage lid (30), and the spline stroke is smooth.

  The protruding amount, size, number, interval, etc. of the protrusions (29a) (30a) can be variously changed, and by changing these, the pressurization of the cage body (29) and the cage lid (30) Can be adjusted. The C-shaped retaining rings (41) and (42) are fitted into annular grooves (17a) and (17b) formed in the outer cylinder main body (17), and between the annular grooves (17a and 17b). By adjusting the distance (the distance between the C-shaped retaining rings (41) and (42)), the pressurization of the cage body (29) and the cage lid (30) can be adjusted. Furthermore, the cage body (29) and the cage lid also depend on the size and number of the through holes (29b) (30b) that facilitate the deformation of the convex portions (29a) (30a) in the axially inward direction. The pressurization of (30) can be adjusted, and by setting these to appropriate values, the cage body (29) and the cage lid (30) will not be deformed due to temperature changes or dimensional variations. The pressurization is adjusted.

  The motor-equipped ball screw device (1) is suitable for use as, for example, an automobile electromagnetic shock absorber. In the electromagnetic shock absorber, the screw shaft (2) linearly moves in the axial direction due to the external force transmitted from the tire, and the ball screw nut (3) and the hollow shaft (5) rotate accordingly. 8), the electromagnetic force generated by the motor (8) is used as the damping force.

  This ball screw device with motor (1) is not limited to an electromagnetic shock absorber, and can also be used as an electric actuator. In this case, the rotational driving force of the motor (8) is converted to the axial thrust of the screw shaft (2) via the ball screw nut (3), and the axial reaction force of the thrust is supported by the bearing (7) and screwed. The shaft (2) is moved linearly, the axial load acting on the screw shaft (2) is applied by the ball screw nut (3), and the torque is supported by the ball spline outer cylinder (4). .

(2) Screw shaft (shaft)
(2b) (2c) Spline track
(4) Ball spline outer cylinder
(16) Ball
(17) Outer cylinder body
(18) Cage
(19) Cage body
(20) Cage lid
(21) (22) Corrugated washer (spring washer = retaining ring)
(23) Main passage
(24) Return passage
(25) Communication passage
(29) Cage body
(30) Cage lid
(29a) (30a) Convex
(29b) (30b) Through hole (hole)
(41) (42) C type retaining ring

Claims (4)

A shaft provided with a spline track, and a ball spline outer cylinder fitted to the shaft via a ball. The ball spline outer cylinder is opposed to the spline track of the shaft so that the spline track constituting the main passage is A substantially cylindrical outer cylinder main body formed, a substantially cylindrical cage main body formed with a return passage and fitted to the inner periphery of the outer cylinder main body, and a return passage and a main passage of the cage main body. In the ball spline formed with a communication passage that communicates with the cage body and a cage lid that is abutted from one end side,
A ball spline, wherein the cage body and the cage lid are assembled with an axial elastic pressure applied thereto.   The cage body and the cage lid are abutted against each other and supported by the outer cylinder body by a pair of retaining rings disposed on both end faces thereof, and at least one of the pair of retaining rings is a spring washer. The ball spline of claim 1, wherein   The cage body and the cage lid are abutted against each other and supported by the outer cylinder body by a pair of C-shaped retaining rings disposed on both end faces thereof. 2. The ball spline according to claim 1, wherein at least one of the convex portions protruding in the axial direction is formed at three or more locations at predetermined intervals in the circumferential direction.   4. The ball spline according to claim 3, wherein a hole for facilitating deformation of the convex portion inward in the axial direction is formed at an end portion of the cage main body and the cage lid formed with the convex portion.

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