JP2015086999A - Ball joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball joint capable of easily changing frictional torque as needed, while suppressing enlargement.SOLUTION: A viscosity of a magnetic viscous fluid 34 is controlled by changing a distance D between a magnet 14 disposed outside of a housing 17 and the magnetic viscous fluid 34 partially disposed between a ball portion 21 and a slide-contact face of a ball seat 16, by a motor 13. An installation space in the housing 17 and an insulating member for electric shock countermeasure become unnecessary in comparison with a case when a coil device and the like are disposed inside of the housing 17, thus enlargement can be suppressed. Frictional torque can be easily controlled by easily changing a viscosity of the magnetic viscous fluid 34 by magnetic force acting on the magnetic viscous fluid from the magnet 14 changed by the change of the distance D between the magnet 14 and the magnetic viscous fluid 34.

Description

  The present invention relates to a ball joint including a magnetorheological fluid in which at least a part is interposed between a holding surface and the ball portion, and controls a friction torque between the ball portion and the holding surface.

  2. Description of the Related Art Conventionally, a ball joint used for a suspension device of a vehicle such as an automobile or a steering device is a ball stud that is a ball side member having a ball portion and a stud portion that is a shaft portion protruding from the ball portion. A cylindrical ball sheet that is a bearing sheet made of synthetic resin or the like that has a sliding contact surface that is a holding surface that rotatably holds the ball portion of the ball stud, and a ball that holds the ball portion on the sliding contact surface And a bottomed cylindrical housing which is a receiving side member including a housing body which is a receiving portion having an inner chamber for receiving a sheet.

  For example, in vehicles such as medium-sized trucks, when the up / down movement of the drag link of the steering device with ball joints on both ends is greatly affected, such as when driving on rough roads, While high friction torque between the ball seat and the ball portion of the ball joint is desired to suppress excessive swinging interference, etc., during normal driving steering, the ease of assembly of the ball joint to the vehicle, and Considering the wear durability of the ball joint, a low friction torque is desirable.

  Therefore, a configuration using a magnetorheological fluid (MR fluid) whose viscosity can be changed by a magnetic force (magnetic field) is known as a lubricant (grease) interposed between the sliding contact surface of the ball seat and the ball portion. . In this configuration, a coil device is embedded in the housing, and a magnetic force (magnetic field) is generated by passing an electric current through the coil device, and the viscosity of the magnetorheological fluid is changed by the strength of the magnetic force to obtain a desired torque. (For example, see Patent Document 1).

Japanese Translation of PCT International Publication No. 2011-522309 (page 8-10, FIG. 2)

  However, in the case of the configuration as described above, a magnetic device (magnetic field) generator such as a coil device, an energizing device for energizing the coil device and a wiring is necessary for the housing, and in order to ensure those spaces in the ball joint, There is a possibility of causing an increase in size, and since a coil device or the like is disposed in the housing, an insulating structure is essential, and the configuration may be complicated.

  And such a subject arises similarly not only about the ball joint for vehicles but the ball joint used for arbitrary places.

  This invention is made | formed in view of such a point, and it aims at providing the ball joint which can change a friction torque easily as needed, suppressing an enlargement.

  The ball joint according to claim 1, wherein a ball side member having a spherical ball portion, a bearing seat having a holding surface for rotatably holding the ball portion, and the ball portion as the holding surface are provided. A receiving side member having a receiving portion for receiving the bearing sheet held, and a magnet that is at least partially interposed between the holding surface and the ball portion, and controls a friction torque between the ball portion and the holding surface. A viscous fluid; a magnet arranged outside the receiving member; and a position variable mechanism that controls the viscosity of the magnetorheological fluid by changing a distance between the magnet and the magnetorheological fluid. Is.

  A ball joint according to a second aspect of the present invention is the ball joint according to the first aspect, wherein the position variable mechanism is a motor that changes the distance between the magnet and the magnetorheological fluid by relatively moving the position of the magnet. Is.

  According to the ball joint of claim 1, the position of the magnet disposed outside the receiving member, the distance between the ball portion and the magnetorheological fluid having at least a part interposed between the holding surface of the bearing seat is variable. By controlling the viscosity of the magnetorheological fluid by changing the mechanism, compared to the case where a coil device or the like is arranged inside the receiving member, the arrangement space in the receiving member or an insulating member for electric shock countermeasures is increased. It becomes unnecessary and can suppress the increase in size, and easily change the viscosity of the magnetorheological fluid by the magnetic force acting on the magnetorheological fluid from the magnet that has changed due to the change in the distance between the magnet and the magnetorheological fluid, thereby facilitating friction torque. Can be controlled.

  According to the ball joint of the second aspect, in addition to the effect of the ball joint of the first aspect, the position variable mechanism moves the position of the magnet relative to each other so that the distance between the magnet and the magnetorheological fluid is increased. By using the motor to be changed, the position variable mechanism can be easily configured with a simple structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged cross-sectional view of a part of a ball joint according to an embodiment of the present invention, in which (a) shows a state in which the viscosity of a magnetorheological fluid is reduced, and (b) shows an increase in the viscosity of a magnetorheological fluid. Indicates the state. It is sectional drawing of a ball joint same as the above.

  The configuration of an embodiment of the present invention will be described below with reference to the drawings.

  1 and 2, reference numeral 11 denotes a ball joint. The ball joint 11 is used, for example, in a steering device of a vehicle such as an automobile, particularly an end of a link member such as a drag link or a stabilizer link. The ball joint 11 includes a ball joint body 12, a motor 13 that is a position variable mechanism (moving mechanism) attached to the ball joint body 12, and a magnet 14 that is moved by the motor 13.

  The ball joint body 12 includes a ball stud 15 made of metal that is a ball side member, a ball seat 16 made of synthetic resin that is a bearing sheet that holds a part of the ball stud 15, and a part of the ball stud 15. In addition, a housing 17 made of metal or the like that is a receiving side member that holds the ball seat 16 and a dust cover 18 that is a dustproof member disposed between the ball stud 15 and the housing 17 are provided. In addition, the vertical direction shown below shall mean the vertical direction of FIG.

  The ball stud 15 includes a ball portion 21 that is a substantially spherical sphere head, and a stud portion 22 that is a round shaft portion having a vertically extending longitudinal direction made of, for example, metal, protruding from the ball portion 21. ing. Further, a thread groove 24 as a connecting portion is formed on the outer peripheral surface on the lower end side of the stud portion 22, and a nut (not shown) is screwed into the thread groove 24, whereby the ball joint body 12 is fixed ( (Not shown).

  The ball sheet 16 is integrally formed in a bottomed cylindrical shape with a synthetic resin. The ball seat 16 is a spherical surface that is located inside and that slidably holds the outer peripheral surface including the equator X of the ball portion 21 in a state where the axial directions of the ball stud 15, the ball seat 16, and the housing 17 substantially coincide. And a sliding contact surface 31 that is a cylindrical holding surface and an opening 32 that communicates with the sliding contact surface 31. The equator X of the ball portion 21 refers to a position where the diameter dimension of the ball portion 21 is maximized in the axial direction of the ball stud 15.

  A magnetorheological fluid 34 as a lubricant is interposed between the sliding contact surface 31 and the ball portion 21. The magnetorheological fluid 34 is also called MR (Magneto Rheological) fluid or the like, and is a variable viscosity fluid whose viscosity (viscosity) changes according to the strength of an external magnetic field (magnetic force). In the present embodiment, the viscosity of the magnetorheological fluid 34 is changed by the magnetic force generated by the magnet 14.

  The opening 32 is located at the lower end, which is one end in the axial direction, in the ball seat 16 and has an opening area smaller than the diameter of the ball portion 21 to prevent the ball portion 21 from coming off from the ball seat 16. doing. Therefore, the ball seat 16 is configured to gradually reduce the diameter from the position corresponding to the equator X of the ball portion 21 toward the opening portion 32 side.

  The housing 17 is also referred to as a socket, and is integrally formed with a link member or the like by using a metal (nonmagnetic material) such as aluminum. The housing 17 includes an inner chamber 35 that holds the ball portion 21 via the ball seat 16, and openings 36 and 37 that communicate with the upper and lower ends that are axial ends of the inner chamber 35 (one and the other). A housing body 38 that is a cylindrical receiving portion and a plug 39 that is a closing member that closes the opening 36 on the upper side of the housing body 38 are provided.

  The inner chamber 35 is a portion into which the ball seat 16 holding the ball portion 21 is press-fitted, that is, a portion that receives the ball portion 21.

  The opening 36 opens in a circular shape at the upper end of the inner chamber 35.

  The opening 37 is a circular opening that communicates with the opening 32 of the ball seat 16 fitted in the inner chamber 35 and protrudes through the stud portion 22 of the ball stud 15, and is formed at the lower end of the inner chamber 35. An opening is formed, and the diameter of the ball seat 16 and the ball stud 15 is prevented from being removed from the inner chamber 35 by being reduced in diameter from the opening 36.

  The housing main body 38 is provided with a support portion 41 that supports the outer edge portion of the plug 39 in a step shape at the inner edge portion of the opening 36. Further, the housing body 38 is formed with a caulking portion 42 for retaining and holding the outer edge portion of the plug 39 supported by the support portion 41. Further, in the housing body 38, a cover mounting portion 43 for fitting and holding the upper end side of the dust cover is formed on the outer edge portion of the opening 37 in a groove shape along the circumferential direction.

  The plug 39 is formed in a circular plate shape from a metal (nonmagnetic material) such as aluminum. The outer edge portion of the plug 39 is deformed by caulking and deforming the caulking portion 42 toward the central axis of the housing body 38 (housing 17) while being supported by the support portion 41, whereby the ball seat 16 held in the inner chamber 35 is obtained. Is held together with the ball stud 15 against the housing 17.

  The dust cover 18 is also called a dust seal or a boot, and is entirely formed of, for example, soft rubber or soft synthetic resin. The dust cover 18 has an upper end fitted to the cover mounting portion 43 of the housing 17 (housing main body 38) and a lower end fitted to the outer periphery of the stud portion 22 of the ball stud 15. Further, the upper end portion of the dust cover 18 is fixed to the cover mounting portion 43 by a clip 47 that is a substantially circular annular member.

  On the other hand, the motor 13 includes, for example, a cylindrical motor body 51 and a rod 52 rotated by the motor body 51, and is disposed outside the ball joint body 12.

  The motor body 51 is rotationally driven by energization from a power supply unit (not shown) disposed on the vehicle body side, and is disposed outside the housing 17 and above the plug 39, for example. The motor body 51 is electrically connected to a power source and a control device (not shown) via a wiring 53, is driven by power supplied from the power source, and is controlled by the control device.

  The rod 52 is formed in, for example, a columnar shape, is inserted through the motor main body 51, and is disposed substantially coaxially with the ball joint main body 12 (the ball seat 16 and the housing 17). A screw groove 52 a is formed on the outer periphery of the rod 52 and is screwed to the motor body 51. The rod 52 is screwed and rotated by the motor main body 51 to advance and retreat in the axial direction, and the position of the tip portion with respect to the ball joint main body 12 can be varied in the vertical direction.

  The magnet 14 is a small one set to a width dimension smaller than the diameter dimension of the rod 52, and is fixed to the lower end portion of the rod 52 in a state of being covered with the covering 55, and the ball joint body 12 (plug 39) Is facing. The magnet 14 moves up and down relatively with respect to the ball joint body 12 by the vertical movement of the tip end of the rod 52 accompanying the rotation of the rod 52. The distance D between the viscous fluid 34 is changed. In other words, by varying the position of the magnet 14, the motor 13 can control the viscosity (viscosity) of the magnetorheological fluid 34.

  Next, the operation of the above embodiment will be described.

  For example, when the above ball joint 11 is used at the end of a drag rod of a vehicle such as a medium-sized truck, the control device drives the motor 13 and moves the rod 52 in the circumferential direction under conditions where low torque is desirable, such as during normal driving. The distance D between the magnet 14 and the magnetorheological fluid 34 is relatively increased by rotating the magnet 14 fixed to the tip of the rod 52 away from the ball joint body 12 (FIG. 1 ( a)). As a result, the magnetic force acting on the magnetorheological fluid 34 from the magnet 14 is relatively lowered, and the viscosity of the magnetorheological fluid 34 is reduced, so that the sliding contact surface 31 of the ball sheet 16 on which the magnetorheological fluid 34 intervenes The friction torque with the ball portion 21 of the ball stud 15 becomes relatively small, and a low torque can be realized.

  On the other hand, under a situation where a high torque is required, for example, when driving on a rough road, the control device drives the motor 13 and rotates the rod 52 in the circumferential direction to fix the magnet 14 to the tip of the rod 52. Is made closer to the ball joint body 12 to relatively reduce the distance D between the magnet 14 and the magnetorheological fluid 34 (FIG. 1 (b)). As a result, the magnetic force acting on the magnetorheological fluid 34 from the magnet 14 relatively increases and the viscosity of the magnetorheological fluid 34 increases, so that the sliding contact surface 31 of the ball seat 16 on which the magnetorheological fluid 34 intervenes The friction torque with the ball portion 21 of the ball stud 15 becomes relatively large, and a high torque can be realized.

  Thus, according to the above-described embodiment, the magnet 14 disposed outside the housing 17 and the magnetorheological fluid 34 partially interposed between the ball portion 21 and the sliding contact surface 31 of the ball seat 16 are provided. By controlling the viscosity of the magnetorheological fluid 34 by changing the distance D between them by the motor 13 and changing the magnetic force of the magnet 14 acting on the magnetorheological fluid 34, for example, a coil device or the like is provided inside the housing 17. Compared with the case where a magnetic action device is provided, an arrangement space in the housing 17 and an insulating member for electric shock measures are not required, and the enlargement of the ball joint 11 can be suppressed, and the magnet 14 and the magnetorheological fluid 34 can be prevented from being enlarged. The friction torque can be easily controlled by easily changing the viscosity of the magnetorheological fluid 34 by the change of the magnetic force acting on the magnetorheological fluid 34 from the magnet 14 that has been changed by the change of the distance D.

  Therefore, since the friction torque according to the vehicle situation can be set arbitrarily, vibration and noise during traveling can be suppressed, and stable vehicle performance can be obtained.For example, the vehicle performance can be improved due to the friction torque of the ball joint 11. It becomes possible.

  In addition, the position variable mechanism can be easily configured with a simple structure by using the motor 13 that relatively moves the position of the magnet 14 and changes the distance D between the magnet 14 and the magnetorheological fluid 34 as the position variable mechanism. Can be configured.

  In the above-described embodiment, the position variable mechanism can be any actuator other than the motor 13.

  The magnet 14 can be disposed at any position where the magnetic force can be adjusted so that the viscosity of the magnetorheological fluid 34 can be varied by changing the distance to the magnetorheological fluid 34. The position can be any position.

  Furthermore, the ball joint 11 can be applied not only as a vehicle suspension device or a steering device, but also as an arbitrary ball joint for a vehicle or an arbitrary ball joint other than a vehicle.

  The present invention can be suitably used for a steering device of a vehicle such as an automobile.

11 Ball joint
13 Motor that is a variable position mechanism
14 Magnet
15 Ball stud as ball side member
16 Ball seat which is a bearing seat
17 Housing as receiving member
21 Ball part
31 Sliding contact surface as a holding surface
34 Magnetorheological fluid
38 Housing body as receiving part

Claims (2)

A ball side member having a spherical ball portion;
A bearing seat provided therein with a holding surface for rotatably holding the ball portion;
A receiving side member provided with a receiving portion for receiving the bearing seat holding the ball portion on the holding surface;
A magnetorheological fluid in which at least a part is interposed between the holding surface and the ball portion, and controls a friction torque between the ball portion and the holding surface;
A magnet disposed outside the receiving member;
A ball joint comprising: a position variable mechanism that controls a viscosity of the magnetorheological fluid by changing a distance between the magnet and the magnetorheological fluid. The ball joint according to claim 1, wherein the position variable mechanism is a motor that relatively moves the position of the magnet to change the distance between the magnet and the magnetorheological fluid.

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