Suspension device

Abstract

To achieve a structure which easily reduces manufacturing cost.SOLUTION: A lower shell 3, an inner tube 61 and a lower bush 62 are coupled and fixed to each other in the state where an end part on one side in an axial direction of the lower shell 3 is sandwiched in the axial direction by the inner tube 61 and the lower bush 62.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 manufacturing costs by reducing the number of parts and / or facilitating the assembly work.

[0007] In the suspension device described in JP 2010-228579 A, ​​a cylindrical outer tube and a support tube, each of which extends vertically, and a cylindrical mounting bush, each of which extends substantially horizontally, are fixed to each other via a substantially disk-shaped connecting member. That is, the suspension device described in JP 2010-228579 A has a large number of parts because of the connecting member, which may cause the assembly work and parts management to become complicated, and may increase the manufacturing cost. In addition, the outer tube and the support tube, and the mounting bush must be fixed to the connecting member individually by welding or the like. This fixing work is complicated, and this aspect may also increase the manufacturing cost.

[0008] In view of the above-mentioned circumstances, an object of the present invention is to realize a suspension structure that can easily reduce manufacturing costs. [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, a coil spring, and a lower bushing. The upper shell has a cylindrical shape. The lower shell is disposed on one axial side 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 is rotatably supported inside the upper shell. The bearing unit is disposed between the other axial side portion of the ball screw shaft and the upper shell, 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. The lower bushing couples and fixes one axial end of the lower shell and one axial end of the inner tube. Particularly in the suspension device of the present invention, one axial end of the lower shell is axially sandwiched between the inner tube and the lower bush.

[0010] In a suspension device according to one aspect of the present invention, the lower shell may have a lower shell side bottom and an engagement hole that axially penetrates the lower shell side bottom and has a non-circular opening shape. The inner tube may have an inner tube side bottom and an engagement shaft that protrudes from one axial side surface of the inner tube side bottom toward one axial side. In this case, the lower shell and the inner tube may be joined and fixed with the engagement shaft fitted into the engagement hole and with one axial side surface of the inner tube side bottom abutting against the other axial side surface of the lower shell side bottom.

[0011] In a suspension device according to one embodiment of the present invention, the inner tube may have a connecting hole opening to one axial side of the engagement shaft portion, and the lower bush may have a shaft portion screwed or inserted into the connecting hole.

[0012] In this case, the connecting hole can be configured as a threaded hole having a female thread portion on its inner surface, and the shaft portion can have a male thread portion on its outer surface that screws into the female thread portion.

[0013] Alternatively, in a suspension device according to one aspect of the present invention, the lower bush may have a threaded hole that opens to the other axial side and has a female threaded portion on its inner surface, and the inner tube may have a male threaded portion on its outer surface that screws into the female threaded portion and has a shaft portion that protrudes from one axial side of the engagement shaft portion toward one axial side.

[0014] In a suspension device according to one embodiment of the present invention, the lower bushing can have a pressure flange portion that protrudes radially outward, and the other axial side surface of the pressure flange portion can be abutted against one axial side surface of the lower shell side bottom portion.

[0015] In a suspension device according to one embodiment of the present invention, the lower bushing can have a pressure flange portion that protrudes radially outward, and the other axial side surface of the pressure flange portion can be abutted against one axial side surface of the lower shell side bottom portion. Effect of the Invention

[0016] The suspension of the present invention can facilitate reducing manufacturing costs. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of a suspension device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a suspension device according to a first example of the embodiment. [Diagram 3] FIG. 3 is an enlarged view of the portion X in FIG. [Figure 4] FIG. 4 is an enlarged view of a portion Y in FIG. [Diagram 5] FIG. 5 is an exploded perspective view of the intermediate assembly. [Figure 6] FIG. 6 is an exploded perspective view of the upper shell. [Figure 7] FIG. 7 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 8] FIG. 8 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. [Figure 9] FIG. 9 is a view corresponding to FIG. 4, showing a suspension device according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a view corresponding to FIG. 4, showing a suspension device according to a third embodiment of the present invention. [Figure 11] FIG. 11 is a view corresponding to FIG. 4, showing a suspension device according to a fourth embodiment of the present invention. [Figure 12] FIG. 12 is a view corresponding to FIG. 4, showing a suspension device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [First Example of Implementation] A first embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG.

[0019] First, the structure of the suspension device 1 of this embodiment will be described with reference to Figures 1 to 4. 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, a coil spring 8, and a lower bush 62.

[0020] 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.

[0021] 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 5 to 8 and the left side in Figures 2 to 4, 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 5 to 8 and the right side in Figures 2 to 4.

[0022] 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.

[0023] The shell body 13 includes a cylindrical portion 15 and a lower-shell-side bottom portion 16 that closes an opening on one axial side of the cylindrical portion 15 .

[0024] 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.

[0025] The lower shell side bottom 16 has an engagement hole 19 that penetrates the center in the axial direction and has a non-circular opening shape. 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.

[0026] 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.

[0027] One axial end of the lower retainer 14 abuts against the other axial end of a first lock nut 23 that is screwed onto the male thread portion 18 of the shell body 13. This prevents the lower retainer 14 from displacing to one axial side relative to the shell body 13. In this example, the first lock nut 23 is prevented from loosening by having one axial end of the first lock nut 23 abut 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.

[0028] 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.

[0029] 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.

[0030] The ball screw shaft 4 has a male ball screw groove 27 on the outer peripheral surface of one axial side portion, 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 of 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.

[0031] 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.

[0032] The bearing unit 5 includes a bearing holder 34, a pressing plate 35, and a pair of rolling bearings 36a, 36b.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] With the above-described configuration, the ball screw shaft 4 is rotatably supported inside the upper shell 2 by the bearing unit 5.

[0043] 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.

[0044] The ball screw shaft 4 has a bottomed hole 56 that opens to one end face in the axial direction in the range from one end to the axial middle part in the center, and has an air passage 59 consisting of a radial air hole 57 that penetrates the axial middle part in the radial direction, and an axial air hole 58 that opens to the end face on the other axial side and the radial air hole 57. The bottomed hole 56 is provided to suppress the influence of the increase and decrease in the volume of the space inside the inner tube 61 accompanying the expansion and contraction of the entire length of the suspension device 1 by increasing the volume of the space inside the inner tube 61. In addition, the air passage 59 is provided to suppress the influence of the increase and decrease in the volume of the internal space 60 accompanying the expansion and contraction of the entire length of the suspension device 1 by increasing the volume of the internal space 60 present inside the upper shell 2 and the lower shell 3. Furthermore, the bottomed hole 56 and the air passage 59 also contribute to the weight reduction of the ball screw shaft 4.

[0045] Ball nut 6 has a female ball screw groove 124 on its inner circumferential surface, is screwed into one axial side portion of ball screw shaft 4 where male ball screw groove 27 is formed on its outer circumferential 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 124 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.

[0046] 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.

[0047] 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 124 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.

[0048] 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, an inner tube side bottom portion 68 bent radially inward from one axial end of the cylindrical portion 66, and an engagement shaft portion 69.

[0049] The tube flange portion 67 has, at a plurality of locations in the circumferential direction, screw holes 70 that open onto the other axial side surface.

[0050] The inner tube side 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 caused by the expansion and contraction of the entire length of the suspension 1. The inner tube side bottom 68 also has an inner tube side step 125 at a portion of one axial side surface that is located radially outward of the engagement shaft 69. In this example, the inner tube side step 125 is formed of a flat surface that is perpendicular to the central axis of the inner tube 61 and faces one axial side.

[0051] The engagement shaft portion 69 protrudes from one axial side surface of the inner tube side bottom portion 68 toward one axial side, and has a non-circular contour shape when viewed from the axial direction. In this example, the engagement shaft portion 69 has an outer surface shape that can be fitted (engaged) into the engagement hole 19 of the lower shell 3 without rattle.

[0052] Furthermore, the inner tube 61 has a coupling hole 72 that axially penetrates the inner tube side bottom portion 68 and the engagement shaft portion 69. In this example, the coupling hole 72 is formed by threading a female screw portion provided on the inner peripheral surface of the other axial side portion. 133 and an inner tube side fitting surface portion 134 provided on one axial side portion and configured as a cylindrical surface whose inside diameter does not change in the axial direction. The coupling hole 72 may also be configured as a bottomed hole that opens only to one axial side surface of the engagement shaft portion 69.

[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 base portion 126 , a shaft portion 78 , and a pressing flange portion 79 .

[0055] The annular portion 77 is configured in a cylindrical shape that extends in a direction perpendicular to the central axis of the inner tube 61, that is, in a substantially horizontal direction when the suspension device 1 is mounted on a vehicle.

[0056] The base portion 126 protrudes from the other axial end of the outer circumferential surface of the annular portion 77 toward the other axial side.

[0057] The shaft portion 78 has a cylindrical shape and protrudes toward the other axial side from the other axial side surface of the base portion 126. In this example, the shaft portion 78 has a male thread portion 80 provided on the outer peripheral surface of the other axial side portion, and a lower bushing side fitting surface portion 135 provided on the outer peripheral surface of one axial side portion and configured by a cylindrical surface whose inner diameter does not change in the axial direction.

[0058] The pressing flange portion 79 protrudes radially outward from the radially outer end portion of the base portion 126. The pressing flange portion 79 has a pressing surface 127 on the radially outer portion of the other axial side surface. The pressing surface 127 is perpendicular to the central axis of the shaft portion 78 and is configured as a flat surface facing the other axial side.

[0059] 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.

[0060] 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.

[0061] 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 It is smaller than (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.

[0062] The inner tube 61 has the engagement shaft portion 69 fitted (non-circular fit) into the engagement hole 19 of the lower shell 3, and the inner tube side step portion 125 provided on the inner tube side bottom portion 68 abuts against the other axial side surface of the lower shell side bottom portion 16 of the lower shell 3. In this example, the engagement shaft portion 69 is fitted into the engagement hole 19 without any rattle. However, when carrying out the present invention, the engagement shaft portion of the inner tube can also be fitted into the engagement hole of the lower shell by clearance fit or interference fit. In either case, with the engagement shaft portion 69 fitted into the engagement hole 19 and the inner tube side step portion 125 abutting against the other axial side surface of the lower shell side bottom portion 16, the axial direction of the shaft portion 78 of the lower bushing 62 is threaded into the female thread portion 133 provided on the inner peripheral surface of the other axial side portion of the coupling hole 72 of the inner tube 61. others The inner tube 61 is joined and fixed to the lower shell 3 by screwing in a male thread portion 80 provided on the outer circumferential surface of the side portion and pressing one axial side surface of the lower shell-side bottom portion 16 of the lower shell 3 with a pressing surface 127 provided on the other axial side surface of the pressing flange portion 79 of the lower bushing 62. In other words, the lower shell-side bottom portion 16 provided at one axial end of the lower shell 3 is sandwiched in the axial direction between an inner tube-side step portion 125 of the inner tube 61 and the pressing surface 127 of the lower bushing 62.

[0063] In this example, the inner tube 61 and the lower bush 62 are aligned by fitting (spigot fitting) the inner tube side fitting surface 134 provided on the inner peripheral surface of one axial side portion of the coupling hole 72 and the lower bush side fitting surface 135 provided on the outer peripheral surface of one axial side portion of the shaft portion 78 without any rattle. However, when implementing the present invention, the spigot fitting portion between the inner tube and the lower bushing may be omitted.

[0064] In this example, when the inner tube side step 125 provided on the inner tube side bottom 68 of the inner tube 61 is abutted against the other axial side surface of the lower shell side bottom 16 of the lower shell 3, the axial positions of one axial side surface of the engagement shaft portion 69 of the inner tube 61 and one axial side surface of the lower shell side bottom 16 of the lower shell 3 substantially coincide. Therefore, when the male thread portion 80 of the lower bushing 62 is screwed into the coupling hole 72 of the inner tube 61 and further tightened, a radially inner portion of the pressing surface 127 of the lower bushing 62 abuts or closely faces one axial side surface of the engagement shaft portion 69 of the inner tube 61.

[0065] 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.

[0066] 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.

[0067] In this example, the joint 88 includes a cylindrical coupling 89 and a pair of keys 90a, 90b.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] The structure of the joint 88 is not limited to the above-mentioned structure, and various conventionally known structures can be adopted.

[0072] 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.

[0073] 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.

[0074] The mount member 100 includes an upper member 105 and a lower member 106 .

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The vibration-proof member 101 includes an elastic member 116 and a support member 117 .

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] Furthermore, the suspension system 1 absorbs vibrations and shocks by expanding and contracting its entire length as follows.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] In particular, in the suspension device 1 of this embodiment, the lower shell 3, the lower shell side bottom portion 16 provided at one axial end of the lower shell 3 is axially sandwiched between the inner tube side step portion 125 provided on one axial side of the inner tube side bottom portion 68 of the inner tube 61 and the pressing surface 127 provided on the other axial side of the pressing flange portion 79 of the lower bush 62, and the male thread portion 80 of the lower bush 62 is screwed into the joining hole 72 of the inner tube 61, thereby joining and fixing the lower shell 3, the inner tube 61 and the lower bush 62. That is, unlike the suspension device described in JP 2010-228579 A, ​​it is not necessary to separately fix the outer tube and the support tube and the mounting bush to the joining member by welding or the like, and the assembly work can be facilitated. This makes it easy to reduce manufacturing costs.

[0099] Furthermore, with the suspension device 1 of this example, unlike the suspension device described in JP 2010-228579 A, ​​there is no need to provide a connecting member in addition to the outer tube, the support cylinder, and the mounting bush, so the number of parts can be reduced. From this perspective, it is possible to facilitate assembly work and / or parts management, and it is possible to reduce manufacturing costs.

[0100] In this example, the engagement hole 19 and the engagement shaft portion 69 are engaged in a non-circular shape. Therefore, even if a force is applied in a direction that rotates the lower shell 3 and the inner tube 61 relative to each other, the relative rotation between the lower shell 3 and the inner tube 61 can be prevented. In other words, when the coil spring 8 contracts, a load in the circumferential direction as well as the axial direction may be generated from the coil spring 8 to the lower shell 3. Even in this case, the relative rotation between the lower shell 3 and the inner tube 61 can be prevented.

[0101] In addition, when the ball screw shaft 4 is driven to rotate by the electric motor 7, a torque in the torsional direction is applied to the inner tube 61 via the balls 123 and the ball nut 6. If the inner tube 61 tries to rotate based on this torque, the female thread portion 133 provided in the coupling hole 72 of the inner tube 61 and the male thread portion 80 provided in the shaft portion 78 of the lower bush 62 may loosen. In this example, the engagement hole 19 and the engagement shaft portion 69 are non-circularly fitted to prevent the inner tube 61 from rotating relative to the lower shell 3. Here, the lower shell 3 is prevented from rotating relative to the vehicle body by abutting or closely opposing a step portion provided in the outward flange portion 20 and facing in the circumferential direction with a lower end portion (an end portion on one side in the axial direction) of the coil spring 8. Therefore, even if a torsional torque is applied to the inner tube 61 as the ball screw shaft 4 is rotated by the electric motor 7, the inner tube 61 can be prevented from rotating relative to the vehicle body, and the tightening between the female thread portion 133 of the inner tube 61 and the male thread portion 80 of the lower bush 62 can be reliably prevented from loosening.

[0102] Moreover, according to the suspension device 1 of this embodiment, the assembly work can be easily performed.

[0103] That is, when assembling the suspension device 1, first, as shown in FIG. 5, 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.

[0104] 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. 1238. 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.

[0105] As shown in FIG. 6, a sliding bearing 73 and an oil seal 76 are supported inside the small diameter cylindrical portion 10 of the upper shell 2.

[0106] Next, as shown in FIG. 7, 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.

[0107] 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.

[0108] 7, 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.

[0109] Next, as shown in FIG. 8, after arranging the coil spring 8 around the upper shell 2, the lower shell 3 is supported with respect to the inner tube 61 by the lower bush 62, the output shaft 87 of the electric motor 7 is connected to the ball screw shaft 4, and the casing 98 is Bracket 99 supported and fixed thereto.

[0110] That is, the upper shell 2 is inserted into the coil spring 8 from the axial others side, and the end portion on the other axial side of the coil spring 8 is abutted against the end member 115. Next, the lower shell 3 is arranged around one axial side portion of the upper shell 2, and the engaging hole 19 of the lower shell 3 and the engaging shaft portion 69 of the inner tube 61 are fitted together without play. Next, the male screw portion 80 of the lower bush 62 is screwed into the coupling hole 72 of the inner tube 61 to couple the inner tube 61 and the lower shell 3.

[0111] Also, one axial end portion of the output shaft 87 of the electric motor 7 is connected via the joint 88 to the other axial end portion 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 thereto by screwing or the like.

[0112] 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, one axial side surface of the bearing unit 5 is abutted 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, and 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 the joint 88 to the other axial end portion 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 other axial end portion of the upper shell 2 thereby.

[0113] That is, before the heavy electric motor 7 is supported and fixed to the upper shell 2, the ball screw shaft 4 can be supported inside the upper shell 2 in a state in which the ball screw shaft 4 is positioned in the axial direction relative to the upper shell 2. Therefore, according to the assembly method of the suspension device 1 of this example, the assembly work can be easily performed.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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, according to the suspension 1 of this embodiment, it is easier to ensure the contraction amount of the coil spring 8 compared to the suspension described in JP 2010-228579 A.

[0118] [Second Example of the Implementation Form] A second embodiment of the present invention will be described with reference to FIG. 9. In this embodiment, the axial dimension of the engagement shaft portion 69a provided at one end of the inner tube 61a in the axial direction is shorter than the axial dimension of the engagement shaft portion 69 of the inner tube 61 according to the first embodiment. Therefore, when the inner tube side step portion 125 provided at the inner tube side bottom portion 68 of the inner tube 61a is abutted against the other axial side surface of the lower shell side bottom portion 16 of the lower shell 3, the one axial side surface of the engagement shaft portion 69a of the inner tube 61 is located on the other axial side of the one axial side surface of the lower shell side bottom portion 16 of the lower shell 3. Therefore, when the male thread portion 80 of the lower bush 62 is screwed into the coupling hole 72 of the inner tube 61a and further tightened, a gap exists between the radially inner portion of the pressing surface 127 of the lower bush 62 and the one axial side surface of the engagement shaft portion 69a of the inner tube 61. Therefore, according to the suspension device of this example, the lower shell side bottom portion 16 of the lower shell 3 can be securely clamped with a large force between the inner tube side step portion 125 of the inner tube 61a and the pressing surface 127 of the lower bushing 62. The configurations and effects of other parts are similar to those of the first example of the embodiment.

[0119] [Third Example of the Implementation Form] A third embodiment of the present invention will be described with reference to FIG. 10. In this embodiment, the coupling hole 72a provided in the inner tube 61b is configured as a circular hole. That is, the coupling hole 72a does not have a female thread portion on the inner peripheral surface. In this embodiment, the engagement shaft portion 69a of the inner tube 61b is fitted into the engagement hole 19 of the lower shell 3 without any rattle, and the inner tube side step portion 125 is abutted against the other axial side surface of the lower shell side bottom portion 16 of the lower shell 3, and the shaft portion 78 of the lower bush 62 is inserted into the coupling hole 72a of the inner tube 61b. In this state, a nut 128 is screwed onto the portion of the male thread portion 80 provided on the outer peripheral surface of the shaft portion 78 that protrudes from the other axial end of the coupling hole 72a, and then further tightened to connect the lower shell 3 and the inner tube 61b. b and the lower bush 62 are joined and fixed together.

[0120] According to the suspension device of this example, the connection hole 72a of the inner tube 61b is configured as a circular hole, and there is no need to form a female thread on the inner peripheral surface, so that the processing cost of the inner tube 61b can be reduced. The configurations and effects of other parts are the same as those of the first and second examples of the embodiment.

[0121] [Fourth Example of the Implementation Form] A fourth embodiment of the present invention will be described with reference to FIG. 11. In this embodiment, the coupling hole 72b provided in the inner tube 61c is configured as a stepped hole. That is, the coupling hole 72b has a nut holding portion (countersunk portion) 129 at the other axial end. A nut 128 is fitted and held in the nut holding portion 129. In this embodiment, the nut holding portion 129 has a hexagonal opening shape that is slightly larger than the outer diameter of the nut 128. In this embodiment, the inner tube 61 c With the engaging shaft portion 69a fitted securely into the engaging hole 19 of the lower shell 3 and the inner tube side step portion 125 abutting against the other axial side surface of the lower shell side bottom portion 16 of the lower shell 3, the shaft portion 78 is screwed into the nut 128 fitted into the nut holding portion 129 of the connecting hole 72b and further tightened. This connects and fixes the lower shell 3, the inner tube 61c, and the lower bushing 62.

[0122] According to the suspension device of this example, the amount of protrusion of the shaft portion 78 of the lower bushing 62 from the other axial side surface of the inner tube side bottom portion 68 of the inner tube 61c can be kept shorter than in the structure of the third example of the embodiment.

[0123] In this example, the nut holding portion 129 has a hexagonal opening shape slightly larger than the outer diameter of the nut 128, but when implementing the present invention, the nut holding portion can also have a two-face width shape having a pair of parallel flat surface portions at two radially opposite positions on the inner peripheral surface. Alternatively, the inner diameter of the nut holding portion can be made sufficiently larger than the circumscribed circle diameter of the nut so that a gap large enough to insert a tool between the nut and the nut holding portion can be secured when screwing the nut onto the shaft portion of the lower bush. The configurations and effects of the other parts are the same as those of the first to third examples of the embodiment.

[0124] [Fifth Example of the Implementation Form] A fifth embodiment of the present invention will be described with reference to Fig. 12. In this embodiment, the inner tube 61d does not have a coupling hole penetrating the inner tube side bottom 68 and the engagement shaft portion 69a. Instead, in this embodiment, the inner tube 61d has a shaft portion 130 that protrudes from the center of one axial side surface of the engagement shaft portion 69a toward one axial side. The shaft portion 130 has a male thread portion 131 on its outer circumferential surface.

[0125] Moreover, the lower bushing 62a does not have a shaft portion 78 that protrudes toward the other axial direction side from the other axial direction side surface of the base portion 126. Instead, the lower bushing 62a has a screw hole 132 that opens to the other axial direction side surface of the base portion 126.

[0126] In this example, the engaging shaft portion 69a of the inner tube 61d is fitted into the engaging hole 19 of the lower shell 3 without rattle, and the inner tube side step portion 125 is abutted against the other axial side surface of the lower shell side bottom portion 16 of the lower shell 3. In this state, the shaft portion 130 of the inner tube 61d is screwed into the screw hole 132 of the lower bushing 62a and further tightened, so that the pressing surface 127 provided on the pressing flange portion 79 of the lower bushing 62a abuts against one axial side surface of the lower shell side bottom portion 16 of the lower shell 3. As a result, the lower shell 3, the inner tube 61d, and the lower bushing 62a are joined and fixed together with the lower shell side bottom portion 16 of the lower shell 3 being axially sandwiched between the inner tube side step portion 125 of the inner tube 61d and the pressing surface 127 of the lower bushing 62a. The configuration and the effects of other parts are similar to those of the first and second embodiments. [Explanation of symbols]

[0127] 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 Lower shell side 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 passage 60 Interior Space 61, 61a, 61b, 61c, 61d Inner tube 62, 62a Lower Bush 63 Main body 64 Nut flange part 65 Through hole 66 Cylindrical part 67 Tube flange 68 Inner tube bottom 69, 69a Engagement shaft part 70 Screw hole 71 Ventilation hole 72, 72a, 72b binding 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 Female ball screw groove 125 Inner tube side step 126 Base 127 Pressing surface 128 Nut 129 Nut holder 130 Shaft 131 Male thread 132 Screw hole 133 Female thread 134 Inner tube side mating surface 135 Lower bush side mating surface

Claims

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 on an outer peripheral surface of one axial side portion and rotatably supported inside the upper shell; a bearing unit disposed between the other axial side portion of the ball screw shaft and the upper shell, the bearing unit supporting the ball screw shaft rotatably relative 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; a lower bushing that connects and fixes an end portion of the lower shell on one side in an axial direction and an end portion of the inner tube on one side in an axial direction; Equipped with an end portion of the lower shell on one side in the axial direction is axially sandwiched between the inner tube and the lower bush; The lower shell has a lower shell side bottom portion and an engagement hole that penetrates the lower shell side bottom portion in the axial direction and has a non-circular opening shape, the inner tube has an inner tube side bottom portion and an engagement shaft portion protruding from one axial side surface of the inner tube side bottom portion toward one axial side, the lower shell and the inner tube are joined and fixed in a state in which the engagement shaft portion is fitted into the engagement hole and one axial side surface of the inner tube side bottom portion is abutted against the other axial side surface of the lower shell side bottom portion. Suspension system.

2. the inner tube has a coupling hole that opens to one axial side surface of the engagement shaft portion, The lower bush has a shaft portion screwed or inserted into the coupling hole.

2. The suspension system of claim 1.

3. The coupling hole is a threaded hole having a female thread on an inner circumferential surface, The shaft portion has an outer circumferential surface having a male thread portion that screws into the female thread portion.

3. The suspension system of claim 2.

4. the lower bushing has a threaded hole that opens to the other axial side surface and has a female thread portion on an inner peripheral surface thereof, the inner tube has an outer peripheral surface having a male thread portion that screws into the female thread portion, and has a shaft portion that protrudes from one axial side surface of the engagement shaft portion toward one axial side, 2. The suspension system of claim 1.

5. The lower bush has a pressing flange portion that protrudes radially outward, The other axial side surface of the pressing flange portion is abutted against one axial side surface of the lower shell side bottom portion. A suspension system according to any one of claims 1 to 4.

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