JP2012072867A - Suspension device and vehicle incorporating suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device onto which a load in a direction vertical to a shaft direction can be applied while a motion in a shaft direction of a second structure to a first structure is permitted.SOLUTION: The suspension device includes a first bracket fixed to the first structure, a second bracket fixed to the second structure, a coil spring disposed so as to be freely expanded and contracted between the first and the second brackets, a screw shaft having a spiral screw groove in the outer circumferential surface thereof, a ball screw nut screwed with the screw shaft via a ball and assembled in the second bracket, a spline shaft which has a through-hole through which the screw shaft is penetrated, is formed in a substantially cylindrical shape and has a spline groove formed on the outer circumferential surface thereof along the shaft direction and whose one end is fixed to the ball screw nut, a spline nut assembled in the spline shaft via a ball and guiding the motion in the shaft direction of the second bracket to the first bracket, and a motor fixed to the first bracket and rotationally driving the spline nut.

Description

  The present invention relates to a suspension device that suspends a second structure relative to a first structure, for example.

  As the suspension device, for example, one disclosed in Patent Document 1 is known. This suspension device is disposed between a vehicle body as a first structure and an axle as a second structure, and has a helical thread groove on the outer peripheral surface and a bracket at one end. A screw shaft that is fixed to the vehicle body, a ball screw nut that is screwed to the screw shaft via a large number of balls and that has a gear on the outer peripheral side, and that is coupled to the ball screw nut via the gear. And a motor that rotationally drives the ball screw nut. The screw shaft is slidably inserted into a cylindrical outer cylinder via a sliding member, and one end of the outer cylinder is connected to the axle via a bracket.

  The conventional suspension apparatus configured as described above converts the linear motion of the screw shaft into the rotational motion of the ball screw nut, and transmits the rotational motion of the ball screw nut to the motor via the gear, thereby Generate power. Torque resulting from the electromagnetic force generated by the motor is used as a damping force for suppressing the linear motion of the screw shaft, and shocks, vibrations, and the like applied to the wheels from the road surface unevenness are buffered and transmitted to the vehicle body.

  That is, in this conventional suspension device, while allowing the axial movement of the second structure relative to the first structure using the reverse efficiency of the screw shaft and the regenerative resistance of the motor, The shock that is received is buffered.

JP 2005-256920 A

  In such a conventional suspension, when a load in a direction perpendicular to the axial direction of the suspension device is applied, such a load cannot be applied. For this reason, when a conventional suspension device is used alone, a load acting perpendicularly to the axial direction of the suspension device can be applied, and the axial direction of the second structure relative to the first structure Another member such as a link mechanism that does not hinder the movement must be used.

  The present invention has been made in view of such problems, and the object of the present invention is to allow a load in a direction perpendicular to the axial direction while allowing the axial movement of the second structure relative to the first structure. An object of the present invention is to provide a suspension device that can be loaded.

  The suspension device of the present invention that achieves such an object includes a first bracket fixed to the first structure, a second bracket fixed to the second structure, and the first bracket and the second bracket. A coil spring that is arranged to be contractible between them, a helical thread groove formed on the outer peripheral surface, a screw shaft that is fixed to the first bracket and that moves forward and backward in the second bracket, and a large number of balls. A ball screw nut screwed into the screw shaft and reciprocating in the axial direction of the screw shaft and rotatably assembled to the second bracket; and a through-hole through which the screw shaft passes. A spline shaft that is formed in a cylindrical shape and has a plurality of spline grooves formed along the axial direction on the outer peripheral surface, while one end is fixed to the ball screw nut and disposed through the coil spring; A spline nut that is assembled to the outside of the spline shaft via a large number of balls and that is rotatably held by the first bracket and guides the axial movement of the second bracket relative to the first bracket, and fixed to the first bracket And a motor for rotationally driving the spline nut.

  According to such a suspension device of the present invention, since the ball spline portion composed of the spline shaft and the spline nut is provided, the direction perpendicular to the axial direction of the suspension device as in the conventional suspension device. It is possible to load a load in a direction perpendicular to the axial direction of the suspension device without using another member such as a link mechanism for loading a load acting on the suspension.

1 is a front view showing a first embodiment of a suspension device to which the present invention is applied. It is side surface sectional drawing which shows 1st embodiment of the suspension apparatus to which this invention is applied. It is a perspective view which shows the ball screw part with which this invention is provided. It is a perspective view which shows the ball spline part with which this invention is provided. It is side surface sectional drawing which shows 2nd embodiment of the suspension apparatus to which this invention is applied. It is a perspective view which shows the ball screw spline with which the suspension apparatus shown in FIG. 5 is provided.

  Hereinafter, a suspension device to which the present invention is applied will be described in detail with reference to the accompanying drawings.

  1 and 2 show a suspension device to which the present invention is applied. FIG. 1 is a front view and FIG. 2 is a side sectional view. This suspension device is contractible between the first bracket 1 fixed to the first structure, the second bracket 2 fixed to the second structure, and the first bracket 1 and the second bracket 2. A coil spring 3 to be disposed, a screw shaft 4 having one end fixed to the first bracket 1 and having a helical thread groove formed on the outer peripheral surface, and a screw threaded on the screw shaft 4 via a number of balls. And a ball screw nut 5 that is rotatably held by the second bracket 2, and is fixed to the ball screw nut 5 and has a through hole through which the screw shaft 4 passes, and is configured in a cylindrical shape. When fixed to the first bracket 1, the spline shaft 6, a spline nut 7 that is assembled to the spline shaft 6 through a number of balls and that is rotatably supported by the first bracket 1, And a, a motor 8 for rotationally driving the spline nut 7. The motor 8 is provided with a drive shaft 81, and the drive shaft 81 is provided with a drive gear 82 for transmitting the drive force of the motor 8 to the spline nut 7.

  The first bracket 1 includes a connecting portion 11 that is fixed to the first structure and to which the motor 8 is fixed, and a sleeve portion 12 that rotatably holds the spline nut 7. The part 12 is fixed to the connecting part 11 by a fixing bolt 13. The sleeve portion 12 has a through hole through which the spline nut 7 passes, and is formed in a cylindrical shape. A rotary bearing 14 is provided between the inner peripheral surface of the through hole and the outer peripheral surface of the spline nut 7. Intervene. That is, the spline nut 7 is rotatably supported with respect to the sleeve portion 12. Further, a flange 12 a that engages the coil spring 3 is formed on the outer peripheral surface of the sleeve portion 12.

  On the other hand, the said 2nd bracket 2 is comprised from the connection part 21 fixed to a 2nd structure, and the cylindrical part 22 which has the hollow part 23 which one end opens, and this connection part 21 and the cylindrical part 22 are comprised. The coil spring 3 is integrally formed through a flange portion 24 to be locked. That is, the coil spring 3 is provided between the flange portion 12 a of the sleeve portion 12 and the flange portion 24 of the second bracket 2 to urge the first bracket 1 and the second bracket 2. Further, a flange portion 54 of the ball screw nut 5 described later is fixed to the opening edge of the hollow portion 23 provided in the second bracket 2.

  FIG. 3 is a perspective view showing an example of a ball screw portion provided in the suspension device of the present embodiment. The screw shaft 4 is formed in a substantially cylindrical shape, and a helical thread groove 41 is formed on the outer peripheral surface with a predetermined lead. In the example shown in FIG. 3, two thread grooves 41 a and 41 b are formed on the screw shaft 4 to form a multi-thread screw. In FIG. 3, a part of the ball screw nut 5 is notched for easy understanding.

  On the other hand, the ball screw nut 5 has a through hole through which the screw shaft 4 passes and is formed in a substantially cylindrical shape, and is screwed to the screw shaft 4 via a large number of balls 9. A load ball rolling groove 51 facing the screw groove 41 of the screw shaft 4 is spirally formed on the inner peripheral surface of the through hole. The load ball rolling groove 51 and the screw groove 41 face each other, whereby a load ball rolling path on which the ball 9 rolls while applying a load is formed between the screw shaft 4 and the ball screw nut 5. Will be.

  The ball screw nut 5 is formed with a return passage 52 for the ball 9 along the axial direction, and a pair of end caps 53 are fixed to both ends of the ball screw nut 5 in the axial direction. The pair of end caps 53 is formed with a direction changing path for changing the rolling direction of the ball 9 that has spirally rolled around the screw shaft 4. The ball 9 that has rolled in the loaded ball rolling groove 51 is fed into the return passage 52 through one end cap 53 and is placed at the initial position of the loaded ball rolling groove 51 through the other end cap 53. It is supposed to be returned. That is, the ball screw nut 5 is formed with an infinite circulation path of the ball 9, and the ball screw 5 circulates in the endless circulation path, so that the ball screw nut 5 continues in the axial direction along the screw shaft 4. It is possible to move.

  In this embodiment, a pair of end caps 53 are used to provide the ball screw nut 5 with an infinite circulation path for the ball 9, but the lead of the screw groove 41 formed in the screw shaft 4. It is possible to arbitrarily select means for providing the infinite circulation path according to the above. For example, when the lead of the screw groove 41 is short, a so-called deflector member that returns the ball 9 rolling the screw groove 41 by one turn is used to provide an infinite circulation path for the ball 9, and the deflector member There is no problem even if an infinite circulation path of the ball 9 is provided on the inner peripheral surface of the ball screw nut 5 without providing such other members.

  Further, an opening edge of the hollow portion 23 of the second bracket 2 is fixed to the outer peripheral surface of the ball screw nut 5, and the flange portion 54 to which the spline shaft 6 is fixed, and the hollow portion 23 is inserted into the hollow portion 23. A cylindrical portion 55 is provided. As shown in FIG. 2, a rotary bearing is provided between the outer peripheral surface of the cylindrical portion 55 and the inner peripheral surface of the hollow portion 23, and the ball screw nut 5 is rotatable with respect to the second bracket 2. It is supported by.

  Next, the ball spline part provided in the suspension device according to the present embodiment will be described. FIG. 4 is a perspective view showing an example of a ball spline portion composed of the spline shaft 6 and the spline nut 7. The spline shaft 6 has a through hole 61 through which the screw shaft 4 passes, and is formed in a substantially cylindrical shape. On the other hand, as shown in FIG. It is fixed to the flange portion 54 of the nut 5. A spline groove 62 is formed on the outer peripheral surface of the spline shaft 6 along the axial direction of the spline shaft 6. The spline grooves 62 are arranged in a set of two strips, for example, every 120 ° in the circumferential direction of the spline shaft 6. Such a spline shaft 6 is provided on the same axis so as to penetrate the coil spring 3 provided between the first bracket 1 and the second bracket 2 (see FIG. 1). In FIG. 4, a part of the spline nut 7 is notched for easy understanding.

  On the other hand, the spline nut 7 has a through hole through which the spline shaft 6 passes and is formed in a substantially cylindrical shape. The spline nut 7 is assembled to the spline shaft 6 via a large number of balls 10. On the outer peripheral surface of the spline nut 7, a nut main body 71 facing the inner peripheral surface of the sleeve portion 12 of the first bracket 1 and a nut side gear 72 that meshes with a drive gear 82 provided on the motor 8 are provided. ing.

  The nut body 71 has an infinite circulation path 73 through which the ball 10 circulates infinitely on the inner peripheral surface of the through hole facing the spline shaft 6. The infinite circulation path 73 includes a loaded ball rolling groove facing the spline groove 62 formed on the outer peripheral surface of the spline shaft 6, and an unloaded ball rolling groove formed in parallel with the loaded ball rolling groove. The ball 10 is configured to change the rolling direction of the ball 10 between the loaded ball rolling groove and the unloaded ball rolling groove, and to change the direction of the ball to pass the ball 10 between the grooves. The endless circulation path 73 is open toward the spline shaft 6 in the entire area, and the balls 10 arranged in the endless circulation path 73 circulate in the endless circulation path 73 in a state of facing the spline shaft 6.

  That is, in the configuration of the ball spline portion, when the spline nut 7 rotates, the ball 10 rolls in an infinite circulation path 73 provided in the spline nut 7, whereby the rotational movement of the spline nut 7 is caused by the spline shaft 6. The spline shaft 6 rotates together with the spline nut 7.

  Preload is applied to the ball 10 that rolls in the infinite circulation path 73 while applying a load, so that backlash between the spline shaft 6 and the spline nut 7 is eliminated, and the spline nut 7 to the spline shaft Also when the rotational torque is transmitted to 6, the spline shaft 6 can be advanced and retracted smoothly and accurately in the axial direction.

  Here, the spline groove 62 of the spline shaft 6 shown in FIG. 4 is formed to be a pair of two, but the ball 10 that rolls between the spline nut 7 and the spline shaft 6 is formed. On the other hand, it is sufficient that a preload is applied, and the spline groove 62 can be formed as a single unit without forming a pair.

  In the suspension device to which the present invention is configured as described above, when the motor 8 is energized, the drive shaft 81 provided on the motor 8 is rotationally driven, and the drive is synchronized with the rotation of the drive shaft 81. The gear 82 rotates. The rotational force of the drive gear 82 is transmitted to the spline nut 7 via a nut-side gear 72 provided on the spline nut 7, and the spline nut 7 rotates with respect to the sleeve portion 12 of the first bracket 1. It will be.

  When the spline nut 7 rotates, the ball 10 rolls in an infinite circulation path 73 provided in the spline nut 7, whereby the rotational motion of the spline nut 7 is transmitted to the spline shaft 6, and as a result, the spline shaft 6 Will rotate with the spline nut 7. Since the spline shaft 6 is fixed on the same axial center with respect to the flange portion 54 of the ball screw nut 5, the ball screw nut 5 is connected to the cylinder of the second bracket 2 in synchronization with the rotation of the spline shaft 6. It will rotate with respect to the part 22.

  Since one end of the screw shaft 4 is fixed to the first bracket 1, the ball screw nut 5 moves in the axial direction along the screw shaft 4 while rotating. Here, the ball screw nut 5 is rotatably held on the cylindrical portion 22 of the second bracket 2 via a rotary bearing, and the flange portion 54 is fixed to the opening edge of the second bracket 2. As the ball screw nut 5 moves in the axial direction, the second bracket 2 also moves along the screw shaft 4 in the axial direction.

  On the other hand, in the state where the motor 8 is not energized, if an external force in the axial direction of the suspension device acts on the second structure connected to the second bracket 2, the second bracket 2 and the first bracket 1 The coil spring 3 provided therebetween contracts in the axial direction of the suspension device, and the second bracket 2 moves in the axial direction with respect to the first bracket 1. At this time, the ball screw nut 5 held rotatably with respect to the second bracket 2 moves in the axial direction along the screw shaft 4 while rotating. Further, the spline shaft 6 fixed on the same axis with respect to the ball screw nut 5 also rotates in accordance with the rotational motion of the ball screw nut 5.

  Since the spline shaft 6 forms a ball spline portion in cooperation with the spline nut 7, the balls 10 pass through the infinite circulation path 73 provided in the spline nut 7 as the spline shaft 6 rotates. Thus, the rotational movement of the spline shaft 6 is transmitted to the spline nut 7, and the spline nut 7 rotates together with the spline shaft 6.

  A nut-side gear 72 is provided on the outer peripheral surface of the spline nut 7, and the nut-side gear 72 meshes with a drive gear 82 provided on the motor 8. For this reason, when the spline nut 7 rotates, the rotational movement of the spline nut 7 is transmitted to the motor 8 via the nut side gear 72 and the drive gear 82. As described above, the rotational motion of the spline nut 7 is transmitted to the motor 8 so that the kinetic energy of the spline nut 7 is converted into the electromagnetic energy of the motor 8, and as a result, the rotational motion of the spline nut 7 is attenuated. It has become.

  According to the suspension apparatus of the present invention configured as described above, the coil spring 3 contracts in a state where the motor 8 is not energized, the reverse efficiency of the ball screw portion composed of the screw shaft 4 and the ball screw nut 5 and the motor. By utilizing the regenerative resistance of 8, the axial movement of the second bracket 2 with respect to the first bracket 1 is allowed, and the impact applied to the second structure is buffered and transmitted to the first structure. It is possible.

  In addition, since the suspension device to which the present invention is applied includes the ball spline portion composed of the spline shaft 6 and the spline nut 7, it is possible to apply a load acting in a direction perpendicular to the axial direction of the suspension device. Is possible. As a result, it is not necessary to use a separate member such as a link mechanism for applying a load in a direction perpendicular to the axial direction of the suspension device, unlike the conventional suspension device.

  On the other hand, in the suspension device of the present invention, the screw shaft 4 is resisted against the biasing force of the coil spring 3 provided between the first bracket 1 and the second bracket 2 by energizing the motor 8. It is possible to move or move the ball screw nut 5 along the axial direction to change or hold the position of the second bracket 2 relative to the first bracket 1.

  FIG. 5 is a side sectional view showing a second embodiment of the suspension device to which the present invention is applied.

  In the first embodiment, since the ball screw nut 5 is rotatably supported with respect to the second bracket 2 via a rotary bearing, the second bracket 2 is mounted on the ball screw nut when the motor 8 is not energized. 5 to rotate with respect to 5.

  In the suspension device of the first embodiment having this configuration, for example, when the second structure is suspended from the first structure using four suspension devices, an external force is applied to the second structure. However, when the second structure is suspended from the first structure with a single suspension device, the rotation of the second structure can be suppressed. It is necessary to provide another member such as a link mechanism or an arm for suppressing the rotation of the second structure when an external force is applied.

  On the other hand, in the suspension device of the second embodiment shown in FIG. 5, spline grooves are formed along the axial direction of the screw shaft 100 on the outer peripheral surface of the screw shaft 100 fixed to the first bracket 1. The second spline nut 102 is assembled to the screw shaft 100 via a plurality of balls. That is, in the suspension device according to this embodiment, the ball screw nut 5 and the second spline nut 102 are provided in series with respect to the axial direction of the screw shaft 100 to form a so-called ball screw spline. The components other than the configuration of the ball screw spline according to the present embodiment are the same as those of the first embodiment described above, and therefore the same configurations are denoted by the same reference numerals as those of the first embodiment. Description is omitted.

  FIG. 6 is a perspective view showing an example of the ball screw spline. One end of the screw shaft 100 is fixed to the first bracket 1, and a screw groove 110 is spirally formed on the outer peripheral surface thereof. A spline groove 120 is formed on the outer peripheral surface of the screw shaft 100 along the axial direction of the screw shaft 100. The spline grooves 120 are arranged at intervals of 120 ° in the circumferential direction of the screw shaft 100 as a set of two strips, and are formed so as to intersect with the screw grooves 110.

  The second spline nut 102 has a through hole through which the screw shaft 100 passes, and is formed in a substantially cylindrical shape. A load facing the spline groove 120 of the screw shaft 100 is formed on the inner peripheral surface of the through hole. Ball rolling grooves are formed. Similar to the spline nut 7, the second spline nut 102 has an infinite circulation path for the ball including the loaded ball rolling groove, and the ball circulates in the infinite circulation path. The spline nut 102 moves in the axial direction along the screw shaft 100. The outer diameter of the second spline nut 102 is formed substantially the same as the inner diameter of the hollow portion 23 of the second bracket 2, and the second spline nut 102 is fixed in the hollow portion 23.

  In the suspension device according to the second embodiment configured as described above, the second spline nut 102 is fixed to the hollow portion 23 of the second bracket 2 even when the motor 8 is not energized. While the axial movement of the second bracket 2 with respect to the first bracket 1 is allowed, the rotation of the second bracket 2 with respect to the ball screw nut 5 can be prevented.

  According to such a suspension device according to the second embodiment, the second bracket 2 does not rotate with respect to the ball screw nut 5 even when the second structure is suspended from the first structure using a single body. Therefore, there is no need to provide a separate member such as a link mechanism or an arm for suppressing the rotation of the second structure. Therefore, compared with the suspension device of the first embodiment, it is suitable for a scene where it is used alone.

  In the suspension device of the present invention according to the embodiment described above, the ball spline and the ball screw spline are described as an example in which the ball circulates infinitely, but the stroke amount of the second bracket 2 relative to the first bracket 1 is described. Depending on the situation, the ball circulation may be limited.

  DESCRIPTION OF SYMBOLS 1 ... 1st bracket, 2 ... 2nd bracket, 3 ... Coil spring, 4 ... Screw shaft, 5 ... Ball screw nut, 6 ... Spline shaft, 7 ... Spline nut, 8 ... Motor, 9, 10 ... Ball, 41 ... Thread groove, 62 ... Spline groove

Claims (3)

  A first bracket fixed to the first structure, a second bracket fixed to the second structure, a coil spring disposed in a contractible manner between the first bracket and the second bracket, and an outer peripheral surface And a screw shaft that is fixed to the first bracket and that moves forward and backward in the second bracket, and is screwed into the screw shaft via a number of balls, and the shaft of the screw shaft. A ball screw nut that is reciprocally movable in the direction and rotatably assembled to the second bracket, and has a through-hole through which the screw shaft passes, and is formed in a substantially cylindrical shape along the axial direction on the outer peripheral surface. A plurality of spline grooves are formed, one end of which is fixed to the ball screw nut, and a spline shaft disposed through the coil spring, and a plurality of balls are assembled to the outside of the spline shaft via a plurality of balls. And a spline nut that is rotatably held by the first bracket and guides the axial movement of the second bracket relative to the first bracket, and a motor that is fixed to the first bracket and rotationally drives the spline nut; Suspension device with On the outer peripheral surface of the screw shaft, a plurality of ball spline grooves are formed along the axial direction while intersecting with the ball screw groove,
The suspension device according to claim 1, further comprising a second spline nut that is assembled to the screw shaft via a plurality of balls and is fixed to the second bracket.   A vehicle using the suspension device according to claim 1 or 2 as a suspension device for suspending a wheel with respect to a vehicle body.

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