JP2006220292A - Electromagnetic shock absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic shock absorber capable of preventing operation property of a ball screw shaft and a ball screw nut from being impaired when regulating an elongation stroke end of the ball screw nut for the ball screw shaft. <P>SOLUTION: This electromagnetic shock absorber 1 is constituted by screw-fitting the ball screw shaft 12 supported on a shaft guide 14 on a vehicle body side into the ball screw nut 11 fixed to a damper case 13 on a wheel side and connecting a motor 31 with the ball screw shaft 12. A lower stopper part 65 rising from a side of the damper case 13 and an upper stopper part 66 hanging down from a side of the shaft guide 14 are provided to abut the lower stopper part 65 and the upper stopper part 66 mutually at the elongation stroke end where the ball screw nut 11 is thoroughly elongated for the ball screw shaft 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic shock absorber.

  As described in Patent Document 1, as an electromagnetic shock absorber, a ball screw nut supported on a vehicle body side shaft guide is screwed onto a ball screw nut fixed to a wheel side damper case, and a motor is mounted on the ball screw shaft. There is something that combines.

The linear motion of the ball screw nut is converted into the rotational motion of the ball screw shaft, and the motor is rotated by this rotational motion to generate electromagnetic force. The torque against this electromagnetic force is used as the damping force for the linear motion of the ball screw nut. Can be used. On the other hand, it is also possible to perform active control by energizing the motor to rotate the motor, rotating the ball screw shaft by the rotational motion of the motor, and linearly moving the ball screw nut.
JP2004-011823

  In the electromagnetic shock absorber of Patent Document 1, a cushion member made of rubber or the like is attached to the lower end portion of the ball screw shaft, and the lower end of the ball screw shaft is the extended stroke end where the ball screw nut extends with respect to the ball screw shaft. The above-mentioned cushion member is abutted against the lower end surface of the ball screw nut, so that the restriction at the stroke end and the impact at the stroke end can be absorbed.

  However, due to the contact between the cushion member made of rubber or the like and the ball screw nut, a load (rebound load) is applied to the ball screw shaft and the ball screw nut, and the life thereof is impaired. Further, foreign matters such as dust may be generated due to the cushion member being damaged around the lower end portion of the ball screw shaft, and the foreign material may be caught in the ball screw shaft and cause malfunction.

  An object of the present invention is to prevent the operability of the ball screw shaft and the ball screw nut from being impaired when the extension stroke end of the ball screw nut with respect to the ball screw shaft is restricted in the electromagnetic shock absorber.

  According to the first aspect of the present invention, an electromagnetic buffer comprising: a ball screw nut supported by a vehicle body side shaft guide and a ball screw nut fixed to a wheel side damper case; and a motor coupled to the ball screw shaft. The upper stopper part that rises from the damper case side and the upper stopper part that hangs down from the shaft guide side is provided, and the lower stopper part and the upper part at the extension stroke end where the ball screw nut extends with respect to the ball screw shaft. The stopper part can be abutted in the axial direction.

  According to a second aspect of the present invention, in the first aspect of the present invention, the lower cover rising from the damper case side and the upper cover hanging from the shaft guide side are disposed around the ball screw shaft via a dust seal. They are arranged coaxially so as to slide relative to each other.

  According to a third aspect of the present invention, in the second aspect of the present invention, further, a lower stopper portion is provided at an upper end portion of a nut case of a ball screw nut fixed to the damper case, and an upper stopper portion is provided at a lower end portion of the upper cover. It is what I did.

  According to a fourth aspect of the present invention, in the second aspect of the invention, a lower stopper portion is provided at the upper end portion of the lower cover, and an upper stopper portion is provided at the lower end portion of the upper cover.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, an impact absorbing member is provided at an abutting portion between the lower stopper portion and the upper stopper portion.

  According to a sixth aspect of the present invention, in the first aspect of the present invention, the lower cover is further provided outside the upper cover, and a dust seal is provided on the inner periphery of the upper end portion of the lower cover.

(Claim 1)
(a) In the electromagnetic shock absorber, the lower stopper and upper stopper are abutted in the axial direction at the extended stroke end where the ball screw nut extends with respect to the ball screw shaft, and the stroke end is regulated and the shock at the stroke end Make it absorbable. Since the rebound load acts on the damper case via the lower stopper portion and the shaft guide via the upper stopper portion and does not reach the ball screw shaft and the ball screw nut, their life is not impaired. Further, the abutting portion between the lower stopper portion and the upper stopper portion is separated from the ball screw shaft, so that there is no possibility of malfunction due to foreign matters such as dust biting into the ball screw shaft.

(Claim 2)
(b) The lower cover on the damper case side and the upper cover on the shaft guide side cover the periphery of the ball screw shaft, and can prevent dust and water from entering the ball screw shaft.

(Claim 3)
(c) By the abutment of the lower stopper part provided on the nut case of the ball screw nut and the upper stopper part of the upper cover, the restriction of the extended stroke end of the ball screw nut and the impact at the stroke end are absorbed.

  When an upper cover is provided on the outside of the nut case and the abutting part between the lower stopper part and the upper stopper part is provided on the outer periphery of the nut case, foreign matter such as dust generated at the abutting part is shielded from the ball screw shaft by the nut case. Does not adversely affect the ball screw shaft.

(Claim 4)
(d) By the abutment of the lower stopper portion provided on the lower cover and the upper stopper portion of the upper cover, the restriction of the extension stroke end of the ball screw nut and the impact at the stroke end are absorbed.

  When an upper cover is provided on the outer side of the lower cover and an abutting portion between the lower stopper portion and the upper stopper portion is provided on the outer periphery of the lower cover, foreign matter such as dust generated at the abutting portion is shielded from the ball screw shaft by the lower cover. Does not adversely affect the ball screw shaft.

(Claim 5)
(e) By providing an impact absorbing member such as rubber at the abutting portion of the lower stopper portion and the upper stopper portion, it is possible to absorb the impact without generating an abnormal noise when the lower stopper portion and the upper stopper portion are abutted.

(Claim 6)
(f) Since the lower cover is provided outside the upper cover and the dust seal is provided on the inner periphery of the upper end of the lower cover, the seal part of the lower cover and the upper cover is disposed on the inner periphery of the upper end of the lower cover. The part can be made less likely to be damaged by bouncing stones and muddy water.

  1 is an overall sectional view showing an electromagnetic shock absorber, FIG. 2 is a sectional view showing the upper half of FIG. 1, FIG. 3 is a sectional view showing the lower half of FIG. 1, and FIG. FIG. 5 is a plan view showing the mounting structure of the shaft guide, FIG. 6 is a sectional view showing the rebound stopper structure of the ball screw nut, and FIG. 7 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut. FIG. 8 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut, and FIG. 9 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut.

  As shown in FIGS. 1 to 3, the electromagnetic shock absorber 1 is used as, for example, a strut type front suspension, and includes a ball screw unit 10 and a motor unit 30. The ball screw unit 10 engages a ball screw shaft 12 with a ball screw nut 11. The motor unit 30 couples the motor 31 to the ball screw shaft 12 via a bevel gear train 36.

  In the ball screw unit 10, a ball screw shaft 12 supported by a cylindrical shaft guide 14 on the vehicle body side is screwed onto a ball screw nut 11 fixed on the cylindrical damper case 13 side on the wheel side. The damper case 13 includes a wheel side attachment member 15 at the bottom, and attaches the wheel side attachment member 15 to the wheel side. The shaft guide 14 is supported by a vehicle body side mounting member 17 via a mount 16, and the vehicle body side mounting member 17 is fixed to the outer surface of the vehicle body 18 by bolts 17 </ b> A.

  In the ball screw unit 10, a nut case 20 is attached to the ball screw 11 with a bolt 21, and an attachment flange 20 A of the nut case 20 is fixed to an upper flange 13 A of the damper case 13 with a bolt 19.

  The ball screw unit 10 extends upward toward the shaft guide 14 by screwing and penetrating the ball screw shaft 12 from the free end on the damper case 13 side to the ball screw nut 11. The upper end side is rotatably supported by an angular ball bearing 22 inserted into the part. 22A and 22B are bearing nuts for pressing the outer and inner rings of the bearing 22, and 22C is a collar. In addition, a ball that is circulated in a spiral ball holding portion provided on the inner periphery of the ball screw nut 11 is fitted into the spiral thread groove of the ball screw shaft 12.

  In the electromagnetic shock absorber 1, a suspension spring 23 is disposed outside the ball screw unit 10. The suspension spring 23 includes a spring seat 24 seated on the upper end flange 13A of the damper case 13 via a mounting flange 20A of the nut case 20, a lower end flange 61A of the lower cover 61 described later, and a spring seat provided on the vehicle body side mounting member 17. And a seat rubber 26 seated on the seat 25.

  In the motor unit 30, a gear housing 32 is coupled to a motor 31, and a base member 33 provided on the gear housing 32 is fixed to the inner surface of the vehicle body 18 by the bolts 17 </ b> A described above. A motor shaft 34 coupled to the output shaft of the motor 31 is rotatably supported by a gear housing 32 by a ball bearing 35, and a small bevel gear 36A is fixed to the motor shaft 34. An intermediate rotary shaft 37 that is coaxial with the ball screw shaft 12 and orthogonal to the motor shaft 34 is rotatably supported by a gear housing 32 by a ball bearing 38, and a large bevel gear 36 B is fixed to the intermediate rotary shaft 37. The small bevel gear 36A and the large bevel gear 36B mesh with each other to form a bevel gear train 36. The bevel gear train 36 accelerates the rotation of the transmission, in this embodiment the ball screw shaft 12, and transmits it to the motor shaft 34. Configure the gearbox. An end of the intermediate rotating shaft 37 protruding from the gear housing 32 is inserted into the joint 39 and coupled to the ball screw shaft 12.

  In the electromagnetic shock absorber 1, the damper case 13 and the ball screw nut 11 are vertically moved with respect to the ball screw shaft 12 supported by the shaft guide 14 when subjected to a push-up or vibration from the road surface while the vehicle is running. This linear movement is converted into the rotational motion of the ball screw shaft 12 by the combination of the ball screw nut 11 and the ball screw shaft 12, and this rotational motion is transmitted to the motor shaft 34 via the bevel gear train 36. As a result, an electromagnetic force is generated in the motor 31.

  The motor 31 is connected to a control circuit (not shown) or the like, or the electrodes of the motor 31 are connected to form a closed circuit, and torque that resists rotation of the motor shaft 34 caused by electromagnetic force is generated. Thus, an electromagnetic force is generated in the motor 31.

  The torque that resists the rotation of the motor shaft 34 due to the electromagnetic force generated in the motor 31 suppresses the rotational movement of the ball screw shaft 12 and thus acts as a damping force that suppresses the linear movement of the ball screw nut 11. In other words, it acts as a damping force that suppresses expansion and contraction vibration of the suspension spring 23 interposed between the damper case 13 and the vehicle body side mounting member 17.

  In the electromagnetic shock absorber 1, the motor 31 is energized by rotating the motor 31, the ball screw shaft 12 is rotated by the rotational movement of the motor 31, and consequently the ball screw nut 11 is linearly moved to be active. It can also be controlled.

  The motor 31 is used as an electromagnetic force generation source, and various motors such as a DC motor, an AC motor, an induction motor, and the like can be adopted.

  Hereinafter, (A) the layout of the ball screw unit 10 and the motor unit 30, (B) the mounting structure of the shaft guide 14, and (C) the rebound stopper structure of the ball screw nut 11 will be described.

(A) Layout of the ball screw unit 10 and the motor unit 30 (FIGS. 1 to 3)
As shown in FIGS. 1 and 2, the electromagnetic shock absorber 1 fixes a vehicle body side mounting member 17 that supports the shaft guide 14 of the ball screw unit 10 to the outer surface of the vehicle body 18, and the ball screw unit 10 is attached to the vehicle body 18. The base unit 33 of the motor unit 30 is fixed to the inner surface of the vehicle body 18 and the motor unit 30 is arranged inside the vehicle body 18 while being arranged outside.

  The electromagnetic shock absorber 1 is configured such that a motor 31 of a motor unit 30 is orthogonally coupled to a ball screw 12 of a ball screw unit 10 arranged vertically along a vertical direction via a bevel gear train 36 or the like. 31 is placed horizontally in an empty space inside the vehicle body 18.

  In the electromagnetic shock absorber 1, as described above, the bevel gear train 36 of the motor unit 30 constitutes a transmission. A suspension spring 23 is disposed outside the ball screw unit 10.

According to the present embodiment, the following operational effects can be obtained.
(a) The electromagnetic shock absorber 1 can reduce the space occupied by the shock absorber at the lower part of the vehicle body by the amount of the motor unit 30 disposed on the inner side of the vehicle body, and can protect the motor 31 and the wiring from the splinter and muddy water outside the vehicle body.

  (b) Since the electromagnetic shock absorber 1 connects the motor 31 and the ball screw shaft 12 by the bevel gear train 36 and the motor 31 is arranged orthogonally to the ball screw shaft 12, the shock absorber along the axial direction of the ball screw shaft 12 The overall axial length can be shortened, and the stroke of the linear motion of the ball screw nut 11 can be easily secured.

  (c) Since the electromagnetic shock absorber 1 is separated into the ball screw unit 10 and the motor unit 30, at the time of assembly, the ball screw unit 10 is assembled to the lower part of the vehicle body, and the motor unit 30 is assembled to the upper part of the vehicle body. Good assembly can be improved.

  (d) In the electromagnetic shock absorber 1, the bevel gear train 36 interposed between the motor 31 and the ball screw shaft 12 constitutes a transmission, so that the motor 31 interlocked with the linear motion of the ball screw nut 11 is provided. It can be used in the rotation speed range with good operating efficiency.

  (e) Since the electromagnetic shock absorber 1 has the suspension spring 23 arranged outside the ball screw unit 10, the electromagnetic shock absorber 1 can also be applied to a strut type front suspension.

(B) Mount structure of shaft guide 14 (FIGS. 1, 2, 4, and 5)
As shown in FIGS. 1, 2, 4, and 5, the electromagnetic shock absorber 1 supports a shaft guide 14 on a vehicle body side mounting member 17 by a mount 16. The mount 16 supports the shaft guide 14 in a swingable manner by radial ball bearings (43, 45) provided on the front, rear, left and right orthogonal to the central axis of the shaft guide 14. In other words, the mount 16 includes an outer ring 41 configured by an inner peripheral portion of the vehicle body side mounting member 17 and an inner ring 42 disposed inside the outer ring 41. The upper end portion of the shaft guide 14 is arranged, and the outer ring 41, the inner ring 42 and the shaft guide 14 are arranged coaxially with each other.

  The mount 16 has a pair of left and right radial ball bearings 43 on the diameter along the left-right direction of the outer ring 41 and a first pivot 44 that is rotatably provided via a spacer 43A on the inner ring 42. The inner ring 42 is supported by the first pivot 44 so as to be swingable in the front-rear direction. The first pivot 44 that is screwed to the inner peripheral ring 42 is fixed by a set screw 44A that is screwed to the inner peripheral ring 42. Further, on the diameter along the front-rear direction of the inner peripheral ring 42 orthogonal to the axial direction of the first pivot 44, one front and rear each provided rotatably via a pair of front and rear radial ball bearings 45 and a spacer 45A. The second pivot 46 is screwed to the shaft guide 14, and the shaft guide 14 is supported by the second pivot 46 so as to be swingable in the left-right direction. The second pivot 46 that is screwed to the shaft guide 14 is fixed by a set screw 46A that is screwed to the shaft guide 14.

  Thus, the shaft guide 14 is supported so as to be swingable back and forth and left and right with respect to the vehicle body side mounting member 17. The outer ring 41 and the inner ring 42 of the mount 16 support the shaft guide 14. The radial ball bearing 43 and the first pivot 44, and the radial ball bearing 45 and the second pivot 46 are the central axes of the outer ring 41. The single surface is called a support surface of the shaft guide 14 by the mount 16.

  The ball screw shaft 12 that is coaxially supported by the shaft guide 14 by the angular ball bearing 22 that is inserted into the hollow portion of the shaft guide 14 is the same surface as the support surface of the shaft guide 14 by the mount 16 or in the vicinity thereof. In this manner, the motor is coupled to the intermediate rotation shaft 37 on the motor 31 side in a swingable manner in the front-rear and left-right directions through a universal joint (flexible joint) 50 in substantially the same plane.

  The universal joint 50 includes a joint shaft 51 fixed to the upper end portion of the ball screw shaft 12 via a key or the like in a non-rotating state, and a joint shaft 52 connected to the joint shaft 51 by a pin 50A extending in the left-right direction. The joint shaft 53 is connected to the joint shaft 52 by a pin 50B extending in the front-rear direction, and the joint shaft 54 is connected to the joint shaft 53 by a pin 50C extending in the left-right direction. It is inserted into the aforementioned joint 39 and coupled to the intermediate rotating shaft 37 on the motor 31 side. In the present embodiment, the pin 50B is disposed substantially in the same plane as the support surface of the shaft guide 14 by the mount 16. The intermediate rotary shaft 37 inserted into the joint 39 is fixed by a set screw 37A screwed to the joint 39, and the joint shaft 54 inserted to the joint 39 is fixed by a set screw 54A screwed to the joint 39. Fixed.

According to the present embodiment, the following operational effects can be obtained.
(a) The mount 16 supports the shaft guide 14 in a swingable manner on radial bearings 43 and 45 provided on the front, rear, left and right orthogonal to the central axis of the shaft guide 14. Therefore, when the ball screw nut 11 bends (tilts) together with the damper case 13 by lateral input from the wheel side, and the ball screw shaft 12 that follows this ball screw nut 11 bends (tilts), the reaction force of this deflection deformation is obtained. Since it does not occur, the ball screw shaft 12 is not twisted. Therefore, the ball screw shaft 12 follows the deflection of the ball screw nut 11 well, and the smooth rotation of the ball screw shaft 12 and the ball screw nut 11 is not impaired.

  (b) The mount 16 can withstand lateral input from the wheel side by two radial bearings 43 provided on the outer ring 41 and two radial bearings 45 provided on the inner ring 42, and the shaft guide 14 can be It supports smoothly and swingably.

  (c) By using the radial bearings 43 and 45 of the mount 16 as ball bearings, it is possible to ensure rocking performance with low cost and excellent durability.

  (d) The ball screw shaft 12 is connected to the rotating shaft 37 on the motor 31 side so as to be swingable in the front / rear and left / right directions in substantially the same plane as the support surface of the shaft guide 14 by the mount 16. Thereby, when the motor 31 is fixed to the vehicle body via the mount rubber or directly, the ball screw shaft 12 does not receive the bending reaction force from the rotating shaft 37 of the motor 31 and the ball screw nut 11 It can flex well following the above-mentioned deflection.

(C) Rebound stopper structure of the ball screw nut 11 (FIGS. 1, 3, 6, and 7)
As shown in FIGS. 1 and 3, the electromagnetic shock absorber 1 includes a cylindrical lower cover 61 that rises from the damper case 13 side and a cylindrical upper cover 62 that hangs down from the shaft guide 14 side. Are arranged coaxially so as to slide with each other through a dust seal 63. The lower cover 61 and the upper cover 62 cover and seal the ball screw shaft 12 together with the damper case 13 and the shaft guide 14, and prevent dust and water from entering the ball screw shaft 12. The lower cover 61 has the lower end flange 61A overlapped on the upper end flange 13A of the damper case 13 from above the mounting flange 20A of the nut case 20, and is fixed to the upper end flange 13A by bolts 19. The upper cover 62 is attached to the intermediate flange 14A of the shaft guide 14 at the upper end cylindrical portion, and is fixed to the intermediate flange 14A by a bolt 64. The lower cover 61 forms an outer cylinder arranged outside the upper cover 62, and the dust seal 63 is held in an annular seal holding groove 61 </ b> B provided on the inner peripheral portion on the upper end side of the lower cover 61, and the dust seal 63 is attached to the upper cover 62. Touch the outer periphery.

  The nut case 20 of the ball screw nut 11 fixed to the damper case 13 extends the cylindrical portion 20B above the upper end surface of the ball screw nut 11 and enters the inner peripheral side from the lower end opening of the upper cover 62. At the upper end of the cylindrical portion 20B of the nut case 20, a hook-like lower stopper portion 65 that protrudes to the outer periphery is provided. An upper stopper portion 66 is provided at the lower end portion of the upper cover 62 so as to project to the inner periphery. As shown in FIG. 6, the upper stopper portion 66 of the lower end portion of the upper cover 62 locks a retaining ring 66A in an annular groove on the inner periphery of the lower end of the upper cover 62, and impacts the retaining ring 66A via a collar 66B. The absorbing member (rebound rubber) 66C is held. That is, the electromagnetic shock absorber 1 has a lower stopper portion 65 rising from the damper case 13 side and an upper stopper portion 66 hanging from the shaft guide 14 side, and the ball screw nut 11 is a ball screw shaft. The impact absorbing member 66C of the lower stopper portion 65 and the upper stopper portion 66 is abutted in the axial direction at the end of the extended stroke extending to 12, so that the stroke end can be regulated and the shock can be absorbed at the stroke end.

  In the electromagnetic shock absorber 1, a bearing 71 is inserted into a small-diameter step portion at the end protruding through the ball screw nut 11 of the ball screw shaft 12 into the damper case 13, and this is removed by a retaining ring 72. At the same time, the bump cap 73 is rotatably attached to the bearing 71 and held by the nut 74. On the other hand, a bump rubber 75 is press-fitted and fixed to the bottom of the dust case 13, and the lower surface of the bump cap 73 facing this is used as a bump receiving surface 76. The bump rubber 75 is a compression stroke end with respect to the ball screw shaft 12 of the ball screw nut 11 and does not abut against the bump receiving surface 76 of the bump cap 73 to be torsionally deformed. It can absorb the shock at the edge.

According to the present embodiment, the following operational effects can be obtained.
(a) In the electromagnetic shock absorber 1, the lower stopper portion 65 and the upper stopper portion 66 are abutted in the axial direction at the extended stroke end where the ball screw nut 11 extends with respect to the ball screw shaft 12, and the stroke end is regulated. The shock at the stroke end can be absorbed. Since the rebound load acts on the damper case 13 via the lower stopper portion 65 and the shaft guide 14 via the upper stopper portion 66 and does not reach the ball screw shaft 12 and the ball screw nut 11, the life of the rebound load may be impaired. Absent. Further, the abutting portion between the lower stopper portion 65 and the upper stopper portion 66 is separated from the ball screw shaft 12, and there is no possibility of malfunction due to foreign matters such as dust biting into the ball screw shaft 12.

  The extended position of the ball screw nut 11 and the ball screw shaft 12 is determined by the abutting position of the lower stopper portion 65 and the upper stopper portion 66, and the ball screw nut 11 and the bump cap 73 of the ball screw shaft 12 do not come into contact with each other. Even if the suspension spring 23 is provided outside the ball screw unit 10, no load (rebound load) is applied to the ball screw nut 11 and the ball screw shaft 12.

  (b) The lower cover 61 on the damper case 13 side and the upper cover 62 on the shaft guide 14 side cover the periphery of the ball screw shaft 12 and can prevent dust and water from entering the ball screw shaft 12.

  The upper surface side of the ball screw nut 11 is sealed inside the lower cover 61 and the upper cover 62, and the lower surface side of the ball screw nut 11 is sealed inside the damper case 13. As a result, the ball screw nut 11 and the ball screw shaft are sealed. 12 is sealed from the external space by the damper case 13, the shaft guide 14, the lower cover 61, and the upper cover 62.

  (c) Due to the abutment of the lower stopper portion 65 provided on the nut case 20 of the ball screw nut 11 and the upper stopper portion 66 of the upper cover 62, the extension stroke end of the ball screw nut 11 is restricted, and the impact at the stroke end. To absorb.

  When the upper cover 62 is provided outside the nut case 20 and the abutting portions of the lower stopper portion 65 and the upper stopper portion 66 are provided on the outer periphery of the nut case 20, foreign matter such as dust generated at the abutting portion is caused by the nut case 20. It is shielded from the ball screw shaft 12 and does not adversely affect the ball screw shaft 12.

  (d) By providing an impact absorbing member 66C made of rubber or the like at the abutting portion of the lower stopper portion 65 and the upper stopper portion 66, no abnormal noise is generated when the lower stopper portion 65 and the upper stopper portion 66 are abutted. Can absorb shocks.

  (e) Since the lower cover 61 is provided outside the upper cover 62 and the dust seal is provided on the inner periphery of the upper end portion of the lower cover 61, the seal portion between the lower cover 61 and the upper cover 62 is the inner periphery of the upper end portion of the lower cover 61. This seal portion can be made less likely to be damaged by bouncing stones and muddy water.

  FIG. 7 shows a modification of FIG. 6 in which a rebound spring 67A and upper and lower spring sheets 67B and 67C are used as the impact absorbing member 66 of the upper stopper portion 66. The upper spring seat 67B is seated on the lower stopper portion 65 of the nut case 20, and the lower spring seat 67C is seated on a collar 66B provided on the upper stopper portion 66 of the upper cover 62.

  FIG. 8 is a modification of FIG. 6, and the cylindrical portion 20 </ b> B of the nut case 20 of the ball screw nut 11 fixed to the damper case 13 is not extended upward, and the nut case 20 is provided with a lower stopper portion 65. Stopped. The lower cover 61 is an outer cylinder arranged outside the upper cover 62, and a collar-shaped lower stopper portion 81 is provided directly below the seal holding groove 61B on the inner peripheral portion of the upper end side of the lower cover 61, and the outer periphery of the lower end portion of the upper cover 62 is provided. An upper stopper portion 82 is provided to project from the upper portion. The upper stopper portion 82 includes a retaining ring 82A, a collar 82B, and an impact absorbing member (rebound rubber) 82C.

  By the abutment of the lower stopper portion 81 provided on the lower cover 61 and the upper stopper portion 82 of the upper cover 62, the restriction of the extension stroke end of the ball screw nut 11 and the impact at the stroke end are absorbed.

  Since the lower cover 61 is provided outside the upper cover 62 and the dust seal 63 is provided on the inner periphery of the upper end portion of the lower cover 61, the seal portion of the lower cover 61 and the upper cover 62 is disposed on the inner periphery of the upper end portion of the lower cover 61. In addition, the seal portion can be made less likely to be damaged by the spring stone and muddy water.

  FIG. 9 is a modification of FIG. 8, in which the lower cover 61 is an inner cylinder disposed inside the upper cover 62, and the dust seal 63 is held in an annular seal holding groove 61 </ b> B provided in the outer peripheral portion on the upper end side of the lower cover 61. The dust seal 63 was brought into sliding contact with the inner periphery of the upper cover 62. Further, a collar-shaped lower stopper portion 91 is provided immediately below the seal holding groove 61 </ b> B on the outer peripheral portion of the upper end side of the lower cover 61, and an upper stopper portion 92 that protrudes to the inner periphery of the lower end portion of the upper cover 62 is provided. The upper stopper 92 includes a retaining ring 92A, a collar 92B, and an impact absorbing member (rebound case) 92C.

  The contact of the lower stopper portion 91 provided on the lower cover 61 and the upper stopper portion 92 of the upper cover 62 absorbs the restriction at the extension stroke end of the ball screw nut 11 and the impact at the stroke end.

  When the upper cover 62 is provided outside the lower cover 61 and the abutting portion of the lower stopper portion 91 and the upper stopper portion 92 is provided on the outer periphery of the lower cover 61, foreign matter such as dust generated at the abutting portion is caused by the lower cover 61. It is shielded from the ball screw shaft 12 and does not adversely affect the ball screw shaft 12.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

FIG. 1 is an overall sectional view showing an electromagnetic shock absorber. 2 is a cross-sectional view showing the upper half of FIG. FIG. 3 is a cross-sectional view showing the lower half of FIG. FIG. 4 is a cross-sectional view showing the mounting structure of the shaft guide. FIG. 5 is a plan view showing the mounting structure of the shaft guide. FIG. 6 is a cross-sectional view showing a rebound stopper structure of a ball screw nut. FIG. 7 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut. FIG. 8 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut. FIG. 9 is a sectional view showing a modification of the rebound stopper structure of the ball screw nut.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electromagnetic buffer 11 Ball screw nut 12 Ball screw shaft 13 Damper case 14 Shaft guide 20 Nut case 31 Motor 61 Lower cover 62 Upper cover 63 Dust seals 65, 81, 91 Lower stopper portions 66, 82, 92 Upper stopper portion 66C, 82C, 92C Shock absorbing member

Claims (6)

In an electromagnetic shock absorber formed by screwing a ball screw shaft supported by a vehicle body side shaft guide to a ball screw nut fixed to a wheel side damper case, and coupling a motor to the ball screw shaft,
Provided with a lower stopper part that rises from the damper case side and an upper stopper part that descends from the shaft guide side. Electromagnetic shock absorber characterized by being able to collide in the axial direction.   The lower cover rising from the damper case side and the upper cover rising from the shaft guide side are coaxially arranged so as to slide with respect to each other via a dust seal around the ball screw shaft. Electromagnetic shock absorber.   The electromagnetic shock absorber according to claim 2, wherein a lower stopper portion is provided at an upper end portion of a nut case of a ball screw nut fixed to the damper case, and an upper stopper portion is provided at a lower end portion of the upper cover.   The electromagnetic shock absorber according to claim 2, wherein a lower stopper portion is provided at an upper end portion of the lower cover, and an upper stopper portion is provided at a lower end portion of the upper cover.   The electromagnetic shock absorber according to any one of claims 1 to 4, wherein an impact absorbing member is provided at an abutting portion between the lower stopper portion and the upper stopper portion.   The electromagnetic shock absorber according to any one of claims 1 to 5, wherein the lower cover is provided outside the upper cover, and a dust seal is provided on the inner periphery of the upper end portion of the lower cover.

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