Suspension device

Abstract

To achieve a structure which easily reduces the size and the weight.SOLUTION: A ball screw shaft 4 has a male ball screw groove 27 provided on an outer peripheral surface on one side part in an axial direction, and a bottomed hole 56 provided on one side part in the axial direction and opened on only an end surface on one side in the axial direction, and is rotatably supported on the inside of an upper shell 2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a suspension system for supporting wheels on a vehicle body. [Background technology]

[0002] The wheels of an automobile are supported on the body by a suspension system. The suspension system presses the outer circumferential surface of the tire that constitutes the wheel against the road surface, and has the function of mitigating vibrations and shocks transmitted from the road surface to the body of the automobile through the wheel. Some automobile suspension systems have been developed that can control the damping force according to the driving state and road surface conditions, and are being implemented in some automobiles.

[0003] Japanese Patent Laid-Open Publication No. 4-59408 (Patent Document 1) describes a suspension system (active suspension) that uses a hydraulic actuator instead of the shock absorber of a normal suspension system (passive suspension) to control the damping force, etc. The suspension system described in Japanese Patent Laid-Open Publication No. 4-59408 can control the damping force, etc. by controlling the supply and discharge of hydraulic pressure to the hydraulic chamber of the hydraulic actuator according to the driving state, road surface condition, etc. However, since the suspension system described in Japanese Patent Laid-Open Publication No. 4-59408 uses a hydraulic actuator, a hydraulic pump, hydraulic piping, etc. are required, which causes a problem of increased costs.

[0004] In response to this, JP 2010-228579 A (Patent Document 2) describes a suspension device that includes an electromagnetic motor (electric motor) and is capable of applying a force to the sprung and unsprung parts in a direction that moves them closer to or farther away from each other based on the rotational force of the electromagnetic motor. Specifically, the suspension device described in JP 2010-228579 A is configured to convert the rotation of the motor shaft into linear motion in the axial direction of a screw rod by a ball screw mechanism, and apply a force to the sprung and unsprung parts in a direction that moves them closer to or farther away from each other, that is, to adjust the damping force. Since the suspension device described in JP 2010-228579 A uses an electromagnetic motor, it is possible to simplify the structure and reduce costs compared to a structure using a hydraulic actuator, such as the suspension device described in JP 4-59408 A. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-59408 [Patent Document 2] JP 2010-228579 A Summary of the Invention [Problem to be solved by the invention]

[0006] The suspension device described in JP 2010-228579 A has room for improvement in terms of reducing size and weight.

[0007] The suspension described in JP 2010-228579 A rotates a screw rod by an electromagnetic motor, displaces a nut relative to the screw rod in the axial direction, and displaces an outer tube relative to a cover tube in the axial direction, thereby expanding and contracting the entire length. Here, when the entire length of the suspension expands and contracts, the volume of the space present inside the nut support tube connecting the nut and the outer tube increases and decreases. That is, when the entire length of the suspension contracts and the volume of the space decreases, the pressure (internal pressure) of the space increases. If an attempt is made to displace the screw rod and the nut relative to each other in order to further shorten the entire length of the suspension from this state, a large force is required to displace the screw rod and the nut relative to each other because the pressure in the space has increased. For this reason, it is necessary to use a large electromagnetic motor with a large output, which is disadvantageous in terms of making the suspension smaller and lighter.

[0008] In view of the above-mentioned circumstances, an object of the present invention is to realize a suspension structure that can be easily made small and lightweight. [Means for solving the problem]

[0009] A suspension device according to one aspect of the present invention includes an upper shell, a lower shell, a ball screw shaft, a bearing unit, a ball nut, a plurality of balls, an inner tube, an electric motor, and a coil spring. The upper shell has a cylindrical shape. The lower shell is disposed on one axial side portion of the upper shell so as to be capable of relative axial displacement with respect to the upper shell but unable to rotate. The ball screw shaft has a male ball screw groove on the outer peripheral surface of one axial side portion, and a bottomed hole on one axial side portion and opening only to the end face on one axial side, and is supported rotatably inside the upper shell. The bearing unit is disposed between the upper shell and a portion of the ball screw shaft on the other axial side of the bottomed hole, and supports the ball screw shaft rotatably relative to the upper shell. The ball nut has a female ball screw groove on its inner peripheral surface, and is supported around one axial side portion of the ball screw shaft so as to be rotatable relative to the ball screw shaft. Each of the balls is disposed between the male ball screw groove and the female ball screw groove so as to be able to roll freely. The inner tube connects the lower shell and the ball nut to enable integral axial displacement therebetween. The electric motor has an output shaft connected to the other axial end of the ball screw shaft so as to be capable of transmitting torque, and is supported by the other axial end of the upper shell. The coil spring is sandwiched between the upper shell and the lower shell in an axially elastically compressed state.

[0010] In a suspension device according to one aspect of the present invention, the ball screw shaft can have an air passage consisting of a radial air hole opening to the outer peripheral surface of the axial middle portion, and an axial air hole opening to the end face on the other axial side and the radial air hole.

[0011] In the suspension device according to one aspect of the present invention, the inside diameter dimension of the bottomed hole can be larger than the inside diameter dimension of the axial air vent hole. Effect of the Invention

[0012] According to the suspension device according to one aspect of the present invention, it is possible to easily achieve a reduction in size and weight. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a suspension device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of a suspension device according to an embodiment of the present invention. [Diagram 3] FIG. 3 is an enlarged view of the portion X in FIG. [Figure 4] FIG. 4 is an exploded perspective view of the intermediate assembly. [Diagram 5]FIG. 5 is an exploded perspective view of the upper shell. [Figure 6] FIG. 6 is an exploded perspective view showing how the intermediate assembly is supported inside the upper shell and how the mount member is supported relative to the upper shell. [Figure 7] FIG. 7 is an exploded perspective view showing how a coil spring is disposed around the upper shell, the upper shell and the lower shell are combined, and the output shaft of an electric motor is connected to the ball screw shaft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG.

[0015] First, the structure of a suspension device 1 of this embodiment will be described with reference to Figures 1 to 3. The suspension device 1 of this embodiment includes an upper shell 2, a lower shell 3, a ball screw shaft 4, a bearing unit 5, a ball nut 6, a plurality of balls 123, an inner tube 61, an electric motor 7, and a coil spring 8.

[0016] The upper shell 2 has a cylindrical shape with both axially open ends, and has a step portion 122 on the inner peripheral surface of the axially intermediate portion. In this example, the upper shell 2 is configured in a stepped cylindrical shape by connecting the other axial end of the small diameter cylindrical portion 10 located on one axial side and the other axial end of the large diameter cylindrical portion 11 located on the other axial side with a conical cylindrical portion 12 whose diameter increases toward the other axial side. In this example, the upper shell 2 is configured in a stepped cylindrical shape that continues in the circumferential direction. In other words, the upper shell 2 is not divided in the circumferential direction, but is configured as a whole. The large diameter cylindrical portion 11 has a flange portion 9 that protrudes radially inward on the inner peripheral surface of one axial side portion. In this example, the step portion 122 is configured by the other axial side surface of the flange portion 9.

[0017] With respect to the suspension device 1, one axial side refers to the wheel side, i.e., the lower side when assembled to a vehicle, that is, the lower left side in Figures 1 and 4 to 7, and the left side in Figures 2 and 3, and the other axial side refers to the vehicle body side, i.e., the upper side when assembled to a vehicle, that is, the upper right side in Figures 1 and 4 to 7, and the right side in Figures 2 and 3.

[0018] The lower shell 3 is disposed coaxially with the upper shell 2 and has a cylindrical shape. The lower shell 3 is disposed around one axial side portion of the upper shell 2 so as to be displaceable relative to the upper shell 2 in the axial direction but not rotatable. That is, the upper shell 2 and the lower shell 3 are combined so as to be extendable and retractable over their entire length. In this example, the lower shell 3 includes a shell main body 13 and a lower retainer 14.

[0019] The shell body 13 includes a cylindrical portion 15 and a bottom portion 16 that closes an opening on one axial side of the cylindrical portion 15 .

[0020] The cylindrical portion 15 has an elongated hole 17 extending in the axial direction at the other axial side portion, and has a male thread portion 18 on the outer circumferential surface of an axially intermediate portion.

[0021] The bottom 16 has an engagement hole 19 having a non-circular opening shape in the center. Specifically, for example, the inner peripheral surface of the engagement hole 19 can be configured with a pair of flat surfaces parallel to each other and a pair of concave curved surfaces connecting the pair of flat surfaces. Alternatively, the engagement hole 19 can be configured with a spline hole or a polygonal hole such as a rectangular hole.

[0022] Lower retainer 14 has a cylindrical shape. Lower retainer 14 has, at the other axial end, a circular outward flange portion 20 that protrudes radially outward, and has a screw hole 21 that penetrates radially at an intermediate axial portion. Lower retainer 14 is supported around the other axial end of shell body 13 in a state where it is prevented from rotating by arranging (engaging) the tip end of bolt 22 that is screwed into screw hole 21 inside long hole 17 of shell body 13.

[0023] The lower retainer 14 has one axial end abutted against the other axial end of the first lock nut 23 that is screwed into the male thread 18 of the shell body 13. This prevents the lower retainer 14 from being displaced to one axial end relative to the shell body 13. In this example, the one axial end of the first lock nut 23 of The first lock nut 23 is abutted against the other axial end of a second lock nut 24 that is screwed onto the male thread portion 18 of the shell body 13, thereby preventing the first lock nut 23 from loosening.

[0024] One axial end of the coil spring 8 abuts against the other axial side surface of the outward flange portion 20 of the lower retainer 14 via an elastic sheet 25. This restricts displacement of the lower retainer 14 relative to the shell body 13 toward the other axial side.

[0025] Furthermore, the lower retainer 14 has a dust seal 26 on the inner peripheral surface of the other axial end portion. The dust seal 26 has a tip portion in sliding contact with the outer peripheral surface of the upper shell 2 to prevent the intrusion of foreign matter such as muddy water from between the inner peripheral surface of the other axial end portion of the lower shell 3 and the outer peripheral surface of the upper shell 2.

[0026] The ball screw shaft 4 has a male ball screw groove 27 provided on the outer peripheral surface of one axial side portion, and a bottomed hole 56 provided on one axial side portion and opening only on the end face on one axial side, and is rotatably supported inside the upper shell 2. The male ball screw groove 27 has an arc-shaped cross section, and is formed in a spiral shape on the outer peripheral surface of the ball screw shaft 4 in a range from the end on one axial side to a portion located on one axial side relative to the flange portion 9. In this example, the ball screw shaft 4 has a supported portion 28 provided on the other axial side portion rotatably supported by the bearing unit 5 against the inner peripheral surface of the large diameter cylindrical portion 11 of the upper shell 2.

[0027] The supported portion 28 has a large diameter portion 29 on one axial side, a small diameter portion 30 on the other axial side, and a lower step portion 31 facing the other axial side that connects the outer circumferential surface of an end portion on the other axial side of the large diameter portion 29 to the outer circumferential surface of an end portion on one axial side of the small diameter portion 30. The small diameter portion 30 has a cylindrical surface portion 32 on the outer circumferential surface of an end portion on one axial side, and has a male thread portion 33 on the outer circumferential surface of an end portion on the other axial side.

[0028] The bearing unit 5 includes a bearing holder 34, a pressing plate 35, and a pair of rolling bearings 36a, 36b.

[0029] The bearing holder 34 has a crank-shaped cross section. That is, the bearing holder 34 includes a holder cylindrical portion 37, an outward flange portion 38 bent radially outward from the outer peripheral surface of one axial end of the holder cylindrical portion 37, and an inward flange portion 39 bent radially inward from the inner peripheral surface of the other axial end of the holder cylindrical portion 37. The outward flange portion 38 has screw holes 40 penetrating in the axial direction at multiple locations in the circumferential direction.

[0030] The pressing plate 35 has a substantially L-shaped cross section. That is, the pressing plate 35 includes a circular ring portion 41 and a plate cylindrical portion 42 bent from a radially inner end of the circular ring portion 41 toward the other axial side. The circular ring portion 41 has through holes 43 penetrating in the axial direction at a plurality of circumferential positions. The circular ring portion 41 has an outer diameter dimension that is larger than the inner diameter dimension of the flange portion 9 of the upper shell 2 and can be fitted into the inner peripheral surface of the large diameter cylindrical portion 11 of the upper shell 2 without rattle (slightly smaller than the inner diameter dimension of the large diameter cylindrical portion 11). The plate cylindrical portion 42 has an outer diameter dimension that can be fitted into one axial end of the holder cylindrical portion 37 of the bearing holder 34 without rattle.

[0031] Each of the pair of rolling bearings 36a, 36b includes an inner ring 44a, 44b, an outer ring 45a, 45b, and a plurality of rolling elements 46a, 46b. Each of the rolling bearings 36a, 36b is configured as an angular ball bearing in which balls are used as the rolling elements 46a, 46b and a contact angle is provided to the rolling elements 46a, 46b.

[0032] In this example, a face-to-face duplex (DF) type contact angle is provided to each of the rolling elements 46a, 46b of the pair of rolling bearings 36a, 36b. This adjusts the support rigidity of the ball screw shaft 4 to allow a certain degree of oscillating displacement of the ball screw shaft 4 based on the horizontal force acting from the wheels (the allowable oscillating angle of the ball screw shaft 4 is made larger compared to the case where a back-to-back (DB) type contact angle is provided). Each of the pair of rolling bearings may be configured as a tapered roller bearing using tapered rollers as the rolling elements.

[0033] The inner rings 44a, 44b of the pair of rolling bearings 36a, 36 are press-fitted onto one axial side of the cylindrical surface portion 32 of the ball screw shaft 4 with their axial end faces facing each other butting against each other, and are axially sandwiched between the lower step portion 31 and a collar 47 fitted onto the other axial side of the cylindrical surface portion 32. That is, one axial end face of the inner ring 44a of the rolling bearing 36a on one axial side butts against the lower step portion 31, and one axial end face of the collar 47 butts against the other axial end face of the inner ring 44b of the rolling bearing 36b on the other axial side. In this way, the bearing unit 5 is positioned in the axial direction with respect to the ball screw shaft 4. The collar 47 is made of a low-friction material such as oil-impregnated metal and is cylindrical in shape, and is prevented from being displaced toward the other axial side by a nut 48 screwed onto the male thread portion 33 of the ball screw shaft 4. With the above-mentioned configuration, the inner rings 44a, 44b are positioned in the axial direction relative to the ball screw shaft 4.

[0034] The outer rings 45a, 45b of the pair of rolling bearings 36a, 36b are press-fitted into the holder cylindrical portion 37 of the bearing holder 34 with their opposing axial end faces abutting against each other, and are axially sandwiched between one axial side surface of the inward flange portion 39 and the other axial end surface of the plate cylindrical portion 42 of the pressing plate 35. That is, one axial end surface of the outer ring 45a of the rolling bearing 36a on one axial side abuts against the other axial end surface of the plate cylindrical portion 42, and one axial side surface of the inward flange portion 39 abuts against the other axial end surface of the outer ring 45b of the rolling bearing 36b on the other axial side.

[0035] The bearing holder 34 and the pressure plate 35 are fixed to each other by screwing a bolt 49 inserted through the through hole 43 into the screw hole 40, with the outer rings 45a, 45b of the pair of rolling bearings 36a, 36b being axially sandwiched between one axial side surface of the inward flange portion 39 and the other axial end face of the plate cylindrical portion 42.

[0036] The pressure plate 35 fits the outer peripheral surface of the circular ring portion 41 into the inner peripheral surface of the large diameter cylindrical portion 11 of the upper shell 2 without any rattle, and the radially outer end of one axial side surface of the circular ring portion 41 abuts against the step portion 122 of the upper shell 2 (the other axial side surface of the flange portion 9) via the stopper holder 50.

[0037] The bearing holder 34 is prevented from rotating relative to the large diameter cylindrical portion 11 by elastically abutting an O-ring 51 engaged with the outer peripheral surface of the outward flange portion 38 against the inner peripheral surface of the large diameter cylindrical portion 11. An end portion on one axial side of a sleeve 52 fitted securely into the large diameter cylindrical portion 11 of the upper shell 2 abuts against the radially outer end portion of the other axial side surface of the outward flange portion 38 of the bearing holder 34. The sleeve 52 is prevented from displacing toward the other axial side by a lock nut 54 screwed into a female thread portion 53 provided on the inner peripheral surface of the end portion on the other axial side of the large diameter cylindrical portion 11.

[0038] With the above-described configuration, the ball screw shaft 4 is rotatably supported inside the upper shell 2 by the bearing unit 5.

[0039] The bearing holder 34 has an oil seal 55a on the inner circumferential surface of the inward flange portion 39, with its tip portion in sliding contact with the outer circumferential surface of the collar 47, and the pressing plate 35 has an oil seal 55b on its inner circumferential surface, with its tip portion in sliding contact with the outer circumferential surface of the large diameter portion 29 of the ball screw shaft 4. This prevents the grease that lubricates the pair of rolling bearings 36a, 36b from leaking from the spaces between the inner rings 44a, 44b and the outer rings 45a, 45b.

[0040] The bottomed hole 56 is provided in the center of the ball screw shaft 4 in a range from one axial end to an axial middle portion, and is open only to the end face on one axial side. The inner end (the other axial end) of the bottomed hole 56 is provided in the other axial side portion of the ball screw shaft 4, and is located on one axial side of the supported portion 28 around which the bearing unit 5 is arranged. In other words, the ball screw shaft 4 is rotatably supported with respect to the upper shell 2 by the bearing unit 5 arranged between the supported portion 28 provided in a portion away from the bottomed hole 56 on the other axial side, and the large diameter cylindrical portion 11 of the upper shell 2.

[0041] Furthermore, the ball screw shaft 4 has an air passage 59 consisting of a radial air hole 57 opening on the outer peripheral surface of the axial middle portion and an axial air hole 58 opening on the end face on the other axial side and the radial air hole 57. The air passage 59 communicates a space (an internal space on the other axial side) 60a existing on the other axial side of the oil seal 55a on the other axial side, and a space (an internal space on one axial side) 60b existing on one axial side of the oil seal 55b on one axial side, of the internal space 60 existing inside the upper shell 2 and the lower shell 3. For this reason, the radial air hole 57 opens on the outer peripheral surface of a portion of the ball screw shaft 4 located on one axial side of the portion with which the oil seal 55b slides in the axial direction.

[0042] In this example, the radial vent holes 57 penetrate radially through the ball screw shaft 4. That is, the radial vent holes 57 open at two locations on radially opposite sides on the outer peripheral surface of the axially middle portion of the ball screw shaft 4. However, the radial vent holes may be opened at only one location on the outer peripheral surface of the ball screw shaft.

[0043] In this example, the inner diameter dimension d of the bottomed hole 56 56 , the inner diameter dimension d of the axial ventilation hole 58 58 The inner diameter dimension d of the bottomed hole 56 is larger than 56 , the inner diameter dimension d of the axial ventilation hole 58 58 There are no particular limitations on the extent to which the width is made larger than the width of the bottomed hole 56 as long as the strength of the portion where the bottomed hole 56 is formed can be ensured.

[0044] Ball nut 6 has a female ball screw groove 125 on its inner peripheral surface, is screwed into one axial side portion of ball screw shaft 4 where male ball screw groove 27 is formed on its outer peripheral surface (arranged around one axial side portion), and is supported so as to be capable of integral axial displacement with respect to lower shell 3. Each of the multiple balls 123 is arranged freely rollable between male ball screw groove 27 of ball screw shaft 4 and female ball screw groove 125 of ball nut 6, and is circulated by a circulation mechanism (not shown). That is, a ball screw mechanism is configured by ball screw shaft 4, ball nut 6, multiple balls 123, and the circulation mechanism.

[0045] In this example, the ball nut 6 is connected to the lower shell 3 by an inner tube 61 and a lower bush 62 so as to be capable of integral axial displacement.

[0046] The ball nut 6 includes a cylindrical main body 63 and a nut flange 64 protruding radially outward from the other axial end of the main body 63. The main body 63 has a female ball screw groove on its inner circumferential surface. The nut flange 64 has through holes 65 penetrating in the axial direction at multiple locations in the circumferential direction. In this example, as is clear from FIG. 4, the nut flange 64 has a pair of parallel flat surface portions 64a at two radially opposite locations on the outer circumferential surface. That is, the nut flange 64 has a two-face shape.

[0047] The inner tube 61 comprises a cylindrical portion 66, a tube flange portion 67 protruding radially outward from the other axial end of the cylindrical portion 66, a bottom portion 68 bent radially inward from one axial end of the cylindrical portion 66, and an engagement shaft portion 69 protruding toward one axial side from one axial side of the bottom portion 68.

[0048] The tube flange portion 67 has threaded holes 70 at multiple locations in the circumferential direction that open onto the other axial side surface. In this example, as is clear from Fig. 4, the tube flange portion 67 has a pair of parallel flat surface portions 67a at two radially opposite locations on the outer circumferential surface. In other words, the tube flange portion 67 has a two-face shape.

[0049] In this example, the portion of the internal space 60b on one axial side relative to the ball nut 6 and the portion on the other axial side are a pair of flat surface portions 64a of the nut flange portion 64 and a pair of flat surface portions 64b of the tube flange portion 67. 67a and the inner peripheral surface of the upper shell 2. However, the space on one axial side of the ball nut and the space on the other axial side in the axial direction may also be communicated with each other by the male ball screw groove of the ball screw shaft and the female ball screw groove of the ball nut.

[0050] The bottom 68 has ventilation holes 71 at multiple locations in the circumferential direction, opening at a radially outer end of one axial side surface and at a radially middle portion of the other axial side surface. The ventilation holes 71 are provided to connect the space inside the inner tube 61 with the internal space 60, thereby suppressing the effect of an increase or decrease in the volume of the space inside the inner tube 61 that accompanies expansion and contraction of the overall length of the suspension 1.

[0051] The engaging shaft portion 69 has an outer surface shape that allows it to be fitted (engaged) into the engaging hole 19 of the lower shell 3 without rattling.

[0052] Furthermore, the inner tube 61 has a screw hole 72 that passes through the bottom portion 68 and the engagement shaft portion 69 in the axial direction.

[0053] The inner tube 61 is disposed inside the small diameter cylindrical portion 10 of the upper shell 2 so as to be displaceable in the axial direction relative to the upper shell 2. For this purpose, a plain bearing (wear ring) 73 is supported on the inner peripheral surface of one axial side portion of the small diameter cylindrical portion 10, and the inner tube 61 is inserted (fitted) inside the plain bearing 73. The plain bearing 73 is sandwiched from both axial sides by an inward flange portion 74 provided on the small diameter cylindrical portion 10 and a retaining ring 75 engaged with the inner peripheral surface of the small diameter cylindrical portion 10. The upper shell 2 has an oil seal 76 at one axial end of the small diameter cylindrical portion 10, the tip of which is in sliding contact with the outer peripheral surface of the inner tube 61.

[0054] The lower bushing 62 includes an annular portion 77, a shaft portion 78 protruding toward the other axial direction side from the other axial end of the annular portion 77, and a pressing flange portion 79 protruding radially outward from one axial side portion of the shaft portion 78. The shaft portion 78 has a male thread portion 80 on the outer circumferential surface of the other axial end.

[0055] Furthermore, the lower bushing 62 is made of an elastomer such as rubber and is configured in a circular ring shape, and is equipped with an elastic material 81 held inside the circular ring portion 77, and an annular support ring portion 82 held inside the elastic material 81.

[0056] The ball nut 6 is connected and fixed to the inner tube 61 by threading bolts 85, which pass through holes 84 provided at a plurality of circumferential positions of a disk-shaped contact plate 83 and through holes 65 of the nut flange portion 64, into threaded holes 70 of the tube flange portion 67. The inner tube 61 has an annular rebound stopper 86 made of an elastic material such as an elastomer like rubber on one axial side surface of the tube flange portion 67. This prevents the end face on one axial side of the ball nut 6 from directly colliding (metal contacting) with the other axial side surface of the inward flange portion 74 of the upper shell 2 when the lower shell 3 is pulled downward by the weight of the wheels and the ball nut 6 moves to one axial side when the vehicle is lifted up for inspection and maintenance.

[0057] In this example, in a state where the ball nut 6 and the inner tube 61 are joined by the bolt 85, the ball nut 6 and the inner tube 61 can pass through the radial inside of the step portion 122 (flange portion 9) of the upper shell 2. In other words, the circumscribed circle diameter D of the combined body of the ball nut 6 and the inner tube 61 is n The inner diameter dimension d of the step portion 122 (flange portion 9) f (D n <d f ) In addition, the small diameter cylindrical part of the upper shell 2 10 The inner diameter of the ball nut 6 and the inner tube 61 is the circumscribed circle diameter D n and the inner diameter dimension d of the step portion 122 is larger than f It is smaller than.

[0058] The engaging shaft portion 69 of the inner tube 61 is fitted into the engaging hole 19 of the lower shell 3 without any rattle, and one axial side surface of the bottom portion 68 is abutted against the other axial side surface of the bottom portion 16 of the lower shell 3. In this state, the male thread portion 80 of the lower bushing 62 is screwed into the screw hole 72 of the inner tube 61, and one axial side surface of the bottom portion 16 of the lower shell 3 is pressed by the pressing flange portion 79 of the lower bushing 62, thereby connecting and fixing the inner tube 61 to the lower shell 3. In other words, the bottom portion 16 of the lower shell 3 is sandwiched in the axial direction between the bottom portion 68 of the inner tube 61 and the pressing flange portion 79 of the lower bushing 62.

[0059] The electric motor 7 has an output shaft 87 whose tip end (one axial end) is connected to the other axial end of the ball screw shaft 4 so as to transmit torque, and is supported on the other axial end of the upper shell 2.

[0060] The output shaft 87 is connected to the other axial end of the ball screw shaft 4 by a joint 88 so as to be capable of transmitting torque.

[0061] In this example, the joint 88 includes a cylindrical coupling 89 and a pair of keys 90a, 90b.

[0062] Of the pair of keys 90a, 90b, the key 90a on one axial side is bridged between the other axial end of the ball screw shaft 4 and the coupling 89. Specifically, the other axial end of the key 90a on one axial side is coupled to the coupling 89, and one axial side portion is engaged with a notch 91a provided on the other axial end of the ball screw shaft 4. The notch 91a opens to the outer circumferential surface of the other axial end of the ball screw shaft 4 and to the other axial end face. The key 90a on one axial side is prevented from falling off the notch 91a by a coupling member 92a such as a set screw that radially penetrates the key 90a and has a tip engaged with the bottom of the notch 91a.

[0063] Of the pair of keys 90a, 90b, the key 90b on the other axial direction is fitted between one axial end of the output shaft 87 of the electric motor 7 and the coupling 89. Specifically, the key 90b on the other axial direction is coupled to the coupling 89 at one axial end, and engages at the other axial end with a notch 91b provided at one axial end of the output shaft 87. The notch 91b opens to the outer circumferential surface of the end of the output shaft 87 on one axial end and to the end face of the output shaft 87 on one axial end. The key 90b on the other axial side is prevented from falling off the notch 91b by a coupling member 92b such as a set screw that penetrates the key 90b in the radial direction and has a tip engaged with the bottom of the notch 91b.

[0064] In this example, a lower collar 93 is fitted onto the other axial end of the ball screw shaft 4, and an upper collar 94 is fitted onto the other axial end of the output shaft 87 of the electric motor 7. The lower collar 93 has a notch 95 at the other axial end engaged with a key 90a on one axial side, an end face on one axial side abutting or closely facing an upper step portion 96 provided on the ball screw shaft 4, and an end face on the other axial side abutting or closely facing one axial side surface of the coupling 89. The upper collar 94 has a notch 97 at the end on one axial side engaged with a key 90b on the other axial side, an end face on one axial side abutting or closely facing the other axial side surface of the coupling 89, and an end face on the other axial side abutting or closely facing one axial side surface of the casing 98 of the electric motor 7. This prevents the axial position of the coupling 89 from shifting even if the connecting members 92a, 92b become loose.

[0065] The structure of the joint 88 is not limited to the above-mentioned structure, and various conventionally known structures can be adopted.

[0066] The electric motor 7 is supported and fixed to the other axial end of the upper shell 2 by a bracket 99. The bracket 99 includes a lock nut 54, a mount member 100, and a vibration isolating member 101.

[0067] The lock nut 54 includes a cylindrical portion 103 having a male thread portion 102 on the outer circumferential surface of one axial side portion, and a circular ring portion 104 bent radially outward from the other axial end of the cylindrical portion 103. The lock nut 54 is fixed to the upper shell 2 by screwing the male thread portion 102 into the female thread portion 53 of the upper shell 2. The electric motor 7 has a casing 98 supported and fixed to the circular ring portion 104 of the lock nut 54 by bolting or the like.

[0068] The mount member 100 includes an upper member 105 and a lower member 106 .

[0069] The upper member 105 has a substantially U-shaped cross section. That is, the upper member 105 includes a cylindrical portion 107, a lower circular ring portion 108 bent radially outward from one axial end of the cylindrical portion 107, and an upper circular ring portion 109 bent radially outward from the other axial end of the cylindrical portion 107. The suspension device 1 of this example is connected and fixed to the vehicle body by support bolts 110 inserted from one axial side through through holes provided at multiple circumferential positions of the upper circular ring portion 109.

[0070] The lower member 106 has a generally crank-shaped cross section. That is, the lower member 106 includes a cylindrical portion 111, a ring portion 112 bent radially inward from one axial end of the cylindrical portion 111, a bent portion 113 bent radially inward from a radially inner end of the ring portion 112, and an outward flange portion 114 bent radially outward from the other axial end of the cylindrical portion 111.

[0071] The other axial end of the coil spring 8 abuts against one axial end face of the circular ring portion 112 of the lower member 106 via an end member 115. The end member 115 is made of an elastic material such as an elastomer like rubber, and embeds the bent portion 113 of the lower member 106 and covers one axial side face of the circular ring portion 112.

[0072] The upper member 105 and the lower member 106 are joined and fixed to each other by welding or the like, with the radially outer end of one axial side surface of the lower circular ring portion 108 butting against the other axial side surface of the outward flange portion 114.

[0073] The vibration-proof member 101 includes an elastic member 116 and a support member 117 .

[0074] The elastic member 116 is made of an elastic material such as an elastomer such as rubber, and has a generally diamond-shaped cross section that is symmetrical with respect to the axial direction. The elastic member 116 is supported by the lock nut 54 by embedding the radially outer end of the circular ring portion 104 of the lock nut 54.

[0075] The support member 117 is cylindrical and made of a material, such as metal or synthetic resin, that has higher rigidity than the elastic material that constitutes the elastic member 116. The support member 117 is supported around the elastic member 116 by welding the inner circumferential surface to the radially outer end of the elastic member 116. In other words, the elastic member 116 is provided so as to span between the circular ring portion 104 of the lock nut 54 and the support member 117.

[0076] The support member 117 is press-fitted into the cylindrical portion 111 of the lower member 106, and the elastic member 116 is axially sandwiched between the lower circular ring portion 108 of the upper member 105 and the circular ring portion 112 of the lower member 106. That is, the elastic member 116 has one end in the axial direction elastically abutted against the other axial side surface of the circular ring portion 112 of the lower member 106, and has the other end in the axial direction elastically abutted against one axial side surface of the lower circular ring portion 108 of the upper member 105. As a result, the upper shell 2, the members supported inside or around the upper shell 2, and the electric motor 7 are supported with respect to the vehicle body so as to be able to swing about the axial central position of the elastic member 116.

[0077] The electric motor 7 is supported and fixed to the bracket 99 with a radially outer portion of one axial side surface of the casing 98 abutting against a radially inner portion of the other axial side surface of the ring portion 104 of the lock nut 54. As a result, one axial side portion of the electric motor 7 is positioned inside the mount member 100, and the amount by which it protrudes toward the other axial side beyond the mount member 100 is reduced.

[0078] The coil spring 8 is disposed around the upper shell 2, and is sandwiched between the upper shell 2 and the lower shell 3 in a state in which it is elastically compressed in the axial direction. Specifically, the coil spring 8 is sandwiched between a sheet 25 supported by, for example, attachment to the other axial side surface of the outward flange portion 20 of the lower retainer 14, and an end member 115 supported by the upper shell 2 via a bracket 99.

[0079] The suspension device 1 of this embodiment includes a bump stopper 118 made of an elastomer such as rubber or urethane. The bump stopper 118 is cylindrical and supported by the stopper holder 50 inside the conical cylinder portion 12 of the upper shell 2 and around the axial middle portion of the ball screw shaft 4. The bump stopper 118 is crushed by the contact plate 83 when an upward impact load is applied to an end portion on one axial side of the lower shell 3 and the ball nut 6 moves toward the other axial side as the lower shell 3 moves toward the other axial side. That is, the bump stopper 118 is provided to absorb the impact load applied to the lower shell 3 and to prevent the contact plate 83 from directly colliding (metal contact) with one axial side surface (pressing plate 35) of the bearing unit 5.

[0080] The stopper holder 50 is formed by bending a metal plate such as a steel plate into an L-shaped cross section. That is, the stopper holder 50 includes a circular ring portion 119 and a cylindrical portion 120 bent from a radially inner end of the circular ring portion 119 toward one side in the axial direction. The stopper holder 50 is supported with respect to the upper shell 2 by sandwiching the circular ring portion 119 between the flange portion 9 of the upper shell 2 and the pressing plate 35 of the bearing unit 5 in the axial direction.

[0081] The bump stopper 118 is supported around the ball screw shaft 4 by having the other axial end fitted onto the cylindrical portion 120 of the stopper holder 50, and radially inward deformation when crushed in the axial direction is restricted. That is, the inner peripheral surface of the other axial side portion of the bump stopper 118 is fitted onto the cylindrical portion 120, and the shape of the inner peripheral surface of one axial side portion is designed so that the bump stopper 118 does not come into contact with the outer circumferential surface of the ball screw shaft 4 even when crushed in the axial direction.

[0082] In this example, the bump stopper 118 has an outer diameter equal to or smaller than the inner diameter of the flange portion 9, and preferably an outer diameter slightly smaller than the inner diameter of the flange portion 9. As a result, the outer peripheral surface of the other axial end of the bump stopper 118 abuts against or closely faces the inner peripheral surface of the flange portion 9 of the upper shell 2, thereby restricting radially outward deformation when the bump stopper 118 is crushed in the axial direction.

[0083] The cylindrical portion 120 of the stopper holder 50 has an inner diameter d n Smaller than outer diameter D h (d n > D hTherefore, when an upward impact load is applied to one axial end of the lower shell 3, the ball nut 6 moves to the other axial side and the bump stopper 118 is crushed, the contact plate 83 can move to the other axial side up to the periphery of the cylindrical portion 120. In short, the amount of relative axial displacement of the lower shell 3 with respect to the upper shell 2 can be increased by the axial dimension of the contact plate 83.

[0084] The suspension device 1 of this example supports the other axial end of the upper shell 2 on the vehicle body via a mount member 100, and supports a wheel on one axial end of the lower shell 3 via a lower bush 62. In other words, the suspension device 1 is supported so as to span between the vehicle body and the wheel, with the upper shell 2 disposed on the upper side and the lower shell 3 disposed on the lower side.

[0085] The suspension device 1 presses the outer circumferential surface (tread) of the tire that constitutes the wheel against the road surface based on a force that presses the lower shell 3 toward one axial side (downward) relative to the upper shell 2 due to the elastic restoring force of the coil spring 8.

[0086] Furthermore, the suspension system 1 absorbs vibrations and shocks by expanding and contracting its entire length as follows.

[0087] That is, when an upward (thrust-up) force is applied to one axial end of the lower shell 3 due to vibrations or shocks from the road surface, the lower shell 3 elastically contracts the coil spring 8, rotates the ball screw shaft 4 and the output shaft 87 of the electric motor 7, and moves the ball nut 6 toward the other axial side (upward), displacing relative to the upper shell 2 toward the other axial side. This causes the overall length of the suspension 1 to contract.

[0088] When the upward force due to vibration, impact, etc. is released or reduced, the elastic restoring force of the coil spring 8 causes the lower shell 3 to elastically restore its original state based on the force pressing the lower shell 3 toward one axial side (downward) relative to the upper shell 2, while rotating the ball screw shaft 4 and the output shaft 87 of the electric motor 7 and moving the ball nut 6 toward one axial side (downward), and displacing relative to the upper shell 2 toward one axial side. This causes the overall length of the suspension 1 to extend.

[0089] The suspension system 1 of this embodiment can control the vehicle height, vehicle attitude, and damping force by controlling the power supply to the electric motor 7 in accordance with the driving state, road surface conditions, and the like.

[0090] When controlling the vehicle height or vehicle attitude, electricity is applied to the electric motor 7 to rotate the output shaft 87, thereby rotating the ball screw shaft 4. As the ball screw shaft 4 rotates, the ball nut 6 moves in the axial direction, and the lower shell 3 is displaced axially relative to the upper shell 2, thereby expanding and contracting the overall length of the suspension device 1. As a result, the height of the vehicle body, which supports the upper shell 2 via the mount member 100, is adjusted relative to the wheels, which are supported by the lower shell 3 via the lower bushings 62.

[0091] When controlling the damping force, the amount of electricity supplied to the electric motor 7 is controlled to adjust the rotational resistance of the output shaft 87, and the resistance to the axial movement of the ball nut 6 is adjusted by adjusting the rotational resistance of the ball screw shaft 4. This makes it possible to adjust the damping force by adjusting the speed at which the lower shell 3 displaces axially relative to the upper shell 2 when the overall length of the suspension 1 expands or contracts due to vibrations or impacts from the road surface.

[0092] In particular, in the suspension 1 of this example, the ball screw shaft 4 has a bottomed hole 56 that is provided on one axial side and opens only to the end face on one axial side, so that the volume of the space 124 present inside the inner tube 61 can be increased by the amount of the bottomed hole 56. Therefore, by expanding and contracting the entire length of the suspension 1, the amount of change in pressure (internal pressure) in the space 124 caused by an increase or decrease in the volume of the space 124 present inside the inner tube 61 can be reduced. As a result, the influence of an increase or decrease in the volume of the space 124 caused by the expansion and contraction of the entire length of the suspension 1 can be suppressed.

[0093] For this reason, even when the ball screw shaft 4 and the ball nut 6 are relatively displaced to further shorten the overall length of the suspension 1 from a state in which the overall length of the suspension 1 has been contracted and the volume of the space 124 has been reduced, the force for rotationally driving the ball screw shaft 4 does not become excessively large. Therefore, a relatively small and lightweight motor can be used as the electric motor 7, making it easy to make the suspension 1 small and lightweight.

[0094] The ball screw shaft 4 has an air passage 59 that communicates a space (internal space on the other axial side) 60a existing on the other axial side of the oil seal 55a on the other axial side, and a space (internal space on one axial side) 60b existing on one axial side of the oil seal 55b on one axial side, among the internal spaces 60 existing inside the upper shell 2 and the lower shell 3. Piece Side internal space 60 b 1712708894282_0 The reason for this is explained below.

[0095] When the lower shell 3 is displaced axially in the other direction relative to the upper shell 2 in order to contract the overall length of the suspension device 1, Piece Side internal space 60 b The volume of the Piece Side internal space 60 bThe pressure inside (internal pressure) increases. Piece Side internal space 60 b If an attempt is made to further shorten the overall length of the suspension device 1 while the internal pressure remains high, a large force may be required to displace the lower shell 3 relative to the upper shell 2.

[0096] In contrast, in this embodiment, the ventilation passage 59 is provided to communicate the internal space 60a on the other axial side with the internal space 60b on one axial side. Piece Side internal space 60 b The air inside the others Side internal space 60 a Therefore, the axial force caused by contracting the entire length of the suspension 1 can be reduced. Piece Side internal space 60 b Internal pressure of From this viewpoint as well, the electric motor 7 can be made smaller and lighter, and the suspension device 1 can be made smaller and lighter.

[0097] Furthermore, in the suspension device 1 of this embodiment, the inside diameter dimension d 56 The inner diameter d of the axial vent hole 58 provided on the other axial side portion is 58 This allows the weight of the supported portion 28 of the ball screw shaft 4, which is rotatably supported relative to the upper shell 2 by the bearing unit 5, to be made heavier than the weight of one axial side portion, which is the free end, of the ball screw shaft 4. This makes it easier to damp vibrations of the ball screw shaft 4 that are generated when the ball screw shaft 4 is rotationally driven by the electric motor 7.

[0098] However, when carrying out the present invention, the inside diameter of the bottomed hole provided on one axial side of the ball screw shaft is set to be the same as the inside diameter of the axial vent hole provided on the other axial side, or set to be larger than the inside diameter of the axial vent hole. SmallBy increasing the inner diameter of the axial air hole provided on the other axial side portion, the controllability of the ball screw shaft by the electric motor can be improved.

[0099] Moreover, according to the suspension device 1 of this embodiment, the assembly work can be easily performed.

[0100] That is, when assembling the suspension device 1, first, as shown in FIG. 4, a plurality of balls are attached to the periphery of one axial end portion of the ball screw shaft 4. 123 and ball nut 6 are then arranged, and inner tube 61 is joined and fixed to ball nut 6. Furthermore, bump stopper 118 is arranged around an axially middle portion of ball screw shaft 4, and bearing unit 5 is arranged around the other axially side portion. That is, by combining ball screw shaft 4, bearing unit 5, ball nut 6, and bump stopper 118, an intermediate assembly is obtained.

[0101] Specifically, first, the ball nut 6 is attached to one axial end portion of the ball screw shaft 4 where the male ball screw groove 27 is provided, and a plurality of balls are attached to the ball screw shaft 4. 123 8. Next, a bolt 85 is inserted through the through hole 84 of the contact plate 83 and the through hole 65 of the ball nut 6, and further the bolt 85 is screwed into the threaded hole 70 of the tube flange portion 67, thereby joining and fixing the ball nut 6 and the inner tube 61. Further, the ball screw shaft 4 is inserted from one axial side into the bump stopper 118 fitted onto the stopper holder 50, and the bearing unit 5 and the collar 47 are fitted onto the other axial side portion of the ball screw shaft 4. Further, a nut 48 is screwed onto the other axial end of the ball screw shaft 4.

[0102] As shown in FIG. 5, a sliding bearing 73 and an oil seal 76 are supported inside the small diameter cylindrical portion 10 of the upper shell 2.

[0103] Next, as shown in FIG. 6, the intermediate assembly is supported inside the upper shell 2, and the mount member 100 is supported and fixed to the other end of the upper shell 2 in the axial direction.

[0104] Specifically, the intermediate assembly is inserted into the inside of the upper shell 2 from the other axial side. As a result, the inner tube 61 is inserted (fitted) into the sliding bearing 73 supported at the end of one axial side of the upper shell 2, and the ball nut 6 is passed inside the step portion 122 (flange portion 9) and moved to the axial intermediate portion of the small diameter cylindrical portion 10. Then, the radially outer end of one axial side surface of the bearing unit 5 is abutted against the step portion 122 (the other axial side surface of the flange portion 9) via the stopper holder 50, thereby axially positioning the bearing unit 5 relative to the upper shell 2. Then, the sleeve 52 is fitted into the large diameter cylindrical portion 11 of the upper shell 2, and further, the female thread portion 53 provided on the inner peripheral surface of the end of the large diameter cylindrical portion 11 on the other axial side is threaded. Bracket 99 Then, the lock nut 54 is screwed on.

[0105] 6, a shim plate 121 is sandwiched between one axial end face of the lock nut 54 and the other axial end face of the sleeve 52. However, the shim plate 121 may be omitted.

[0106] Next, as shown in FIG. 7, after the coil spring 8 is arranged around the upper shell 2, the lower shell 3 is supported by the lower bush 62 relative to the inner tube 61, the output shaft 87 of the electric motor 7 is connected to the ball screw shaft 4, and the casing 98 is Bracket 99 The support is fixed to the

[0107] That is, the upper shell 2 is axially connected to the coil spring 8. others side, and the other axial end of the coil spring 8 abuts against the end member 115. Next, the lower shell 3 is placed around one axial side portion of the upper shell 2, and the engagement hole 19 of the lower shell 3 is fitted into the engagement shaft portion 69 of the inner tube 61 without any rattle. Next, the male thread portion 80 of the lower bushing 62 is screwed into the threaded hole 72 of the inner tube 61, thereby joining the inner tube 61 and the lower shell 3.

[0108] Also, one end on one axial side of the output shaft 87 of the electric motor 7 is connected via a joint 88 to the end on the other axial side of the ball screw shaft 4 so as to enable torque transmission, and the casing 98 of the electric motor 7 is Bracket 99 supported and fixed to the [reference] by screwing or the like.

[0109] As described above, when assembling the suspension device 1 of this example, an intermediate assembly including the ball screw shaft 4, the bearing unit 5, the ball nut 6, the inner tube 61, and the bump stopper 118 is inserted into the upper shell 2 from the other axial side. Then, by abutting one axial side surface of the bearing unit 5 against the stepped portion 122 (the other axial side surface of the flange portion 9) of the upper shell 2 via the stopper holder 50, the ball screw shaft 4 is supported inside the upper shell 2 in a state where the axial positioning of the ball screw shaft 4 with respect to the upper shell 2 is achieved. Thereafter, the output shaft 87 of the electric motor 7 is connected via a joint 88 to the end on the other axial side of the ball screw shaft 4 so as to enable torque transmission, and the casing 98 of the electric motor 7 is Bracket 99 supported and fixed to the end on the other axial side of the upper shell 2 by [reference].

[0110] That is, before supporting and fixing the heavy electric motor 7 to the upper shell 2, the ball screw shaft 4 can be supported inside the upper shell 2 in a state where the axial positioning of the ball screw shaft 4 with respect to the upper shell 2 is achieved. Therefore, according to the assembling method of the suspension device 1 of this example, the assembling work can be easily performed.

[0111] In contrast, in the suspension device described in JP 2010-228579 A, ​​the ball screw mechanism and the inner tube are supported and fixed to the casing of the electromagnetic motor, and the casing is connected and fixed to the upper support via a mount and vibration-proof rubber. That is, the ball screw mechanism and the inner tube are supported and fixed to the upper support in a state in which they are axially positioned via the heavy electromagnetic motor. Therefore, during assembly work, the heavy electromagnetic motor needs to be handled as a single unit (as a subassembly) with the ball screw mechanism and the inner tube, which makes the assembly work cumbersome.

[0112] Furthermore, in this example, in a state where the ball nut 6 and the inner tube 61 are connected by the bolt 85, the ball nut 6 and the inner tube 61 can pass through the radial inside of the step portion 122 (flange portion 9) of the upper shell 2. Therefore, even if the ball nut 6 is arranged around the ball screw shaft 4 together with the bearing unit 5 and the bump stopper 118 to form an intermediate assembly, and the intermediate assembly is inserted into the inside of the upper shell 2 from an opening on the other axial side of the upper shell 2 with the end portion on one axial side of the intermediate assembly at the front, the ball nut 6 can pass through the inside of the flange portion 9 of the upper shell 2. In short, the ball screw shaft 4, the bearing unit 5, the ball nut 6, the inner tube 61, and the bump stopper 118 supported on the inside of the upper shell 2 can be combined and handled as an intermediate assembly. From this point of view, the assembly work of the suspension device 1 can be facilitated.

[0113] In addition, the process of assembling the suspension device 1 described above includes a process of supporting the intermediate assembly on the inside of the upper shell 2 after assembling the intermediate assembly, and the steps can be performed in a different order or simultaneously as long as no contradiction occurs.

[0114] In the suspension 1 of this embodiment, the lower shell 3 is fitted onto the upper shell 2 so as to be capable of relative displacement in the axial direction, and the coil spring 8 is sandwiched between an end member 115 supported and fixed to the other axial end of the upper shell 2 and the outward flange portion 20 of the lower shell 3. The coil spring 8 elastically contracts as the suspension 1 contracts its entire length, that is, as the upper shell 2 and the lower shell 3 are relatively displaced in a direction approaching each other. The suspension 1 can contract its entire length until the other axial side surface of the inward flange portion 74 of the upper shell 2 and one axial end surface of the ball nut 6 supported by the lower shell 3 collide with each other via the rebound stopper 86. Therefore, the suspension 1 of this embodiment can ensure the contraction amount of the coil spring 8 more easily than the suspension described in JP 2010-228579 A. [Explanation of symbols]

[0115] 1 Suspension system 2 Upper Shell 3 Lower Shell 4 Ball screw shaft 5 Bearing unit 6 Ball nut 7 Electric motor 8 Coil spring 9 Flange 10 Small diameter cylinder part 11 Large diameter cylinder 12 Cone tube 13 Shell body 14 Loretainer 15 Cylindrical section 16 Bottom 17 long hole 18 Male thread 19 Engagement hole 20 Outward flange 21 Screw hole 22 Volts 23 First lock nut 24 Second lock nut 25 sheets 26 Dust seal 27 Male ball screw groove 28 Supported part 29 Large diameter section 30 Small diameter section 31 Lower step 32 Cylindrical surface part 33 Male thread 34 Bearing holder 35 Presser plate 36a, 36b Rolling bearing 37 Holder cylindrical part 38 Outward flange 39 Inward flange 40 screw hole 41 Circular part 42 Plate cylindrical part 43 Through hole 44a, 44b Inner circle 45a, 45b Outer ring 46a, 46b Rolling elements 47 Color 48 Nut 49 Volts 50 Stopper holder 51 O-ring 52 Sleeve 53 Female thread 54 Lock nut 55a, 55b Oil seal 56 Bottomed hole 57 Radial vent 58 Axial Vent 59 Ventilation Channel 60 Interior Space 60a Inner space on other side in axial direction 60b Internal space on one side in the axial direction 61 Inner Tube 62 Lower Bush 63 Main body 64 Nut flange part 64a Flat surface part 65 Through hole 66 Cylindrical part 67 Tube flange 67a Flat surface part 68 Bottom 69 Engagement shaft part 70 Screw hole 71 Ventilation hole 72 Screw hole 73 Plain bearings 74 Inward flange 75 Retaining ring 76 Oil seal 77 Circular Ring 78 Shaft 79 Pressing flange 80 Male thread 81 Elastic material 82 Support ring 83 Contact Plate 84 Through hole 85 volts 86 Rebound Stopper 87 Output shaft 88 Joints 89 Coupling 90a, 90b keys 91a, 91b notch 92a, 92b Connecting members 93 Lower Color 94 Upper Color 95 Cutout 96 Upper step 97 Cutout 98 Casing 99 Bracket 100 Mounting material 101 Vibration-proofing material 102 Male thread 103 Cylindrical part 104 Circular limbus 105 Upper member 106 Lower member 107 Cylindrical part 108 Lower circular part 109 Upper circular part 110 Support bolt 111 Cylindrical part 112 Circular limbus 113 Bend 114 Outward flange part 115 End member 116 Elastic Members 117 Support member 118 Bump Stopper 119 Circular limbus 120 Cylindrical part 121 Shim plate 122 Stepped section 123 Ball 124 Space 125 female ball screw groove

Claims

[Claim 1] an upper shell having a cylindrical shape; a lower shell disposed on one axial side portion of the upper shell so as to be displaceable in the axial direction relative to the upper shell but not rotatable; a ball screw shaft having a male ball screw groove provided on an outer peripheral surface of one axial side portion and a bottomed hole provided on one axial side portion and opening only on an end face on one axial side, the ball screw shaft being rotatably supported inside the upper shell; a bearing unit that is disposed between the upper shell and a portion of the ball screw shaft that is offset from the bottomed hole toward the other side in the axial direction and supports the ball screw shaft rotatably with respect to the upper shell; a ball nut having a female ball screw groove on an inner peripheral surface thereof and supported around one axial end portion of the ball screw shaft so as to be rotatable relative to the ball screw shaft; a plurality of balls rollably disposed between the male ball screw groove and the female ball screw groove; an inner tube that connects the lower shell and the ball nut to enable integral axial displacement of the lower shell and the ball nut; an electric motor having an output shaft connected to the other axial end of the ball screw shaft so as to be capable of transmitting torque, and supported by the other axial end of the upper shell; a coil spring sandwiched between the upper shell and the lower shell in an axially elastically compressed state; Equipped with the ball screw shaft has an air passage including a radial air hole opening on an outer peripheral surface of an axial middle portion and an axial air hole opening to an end face on the other axial side and the radial air hole, The bottomed hole has an inner diameter dimension larger than the inner diameter dimension of the axial vent hole. Suspension system.

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