Suspension device

Abstract

To provide a suspension device which enables reduction of power consumption of an actuator mechanism and enables reduction of a risk of damage without increasing the size of the suspension device.SOLUTION: A suspension device includes: a nut member disposed rotatably around a rotation axis; and a shaft member formed in a cylindrical shape and including an outer surface into which the nut member is assembled. The shaft member is supported so as to reciprocate along the rotation axis in response to rotation of the nut member. A damper mechanism including a damper body and a damper shaft is disposed in the shaft member.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a suspension device that allows adjustment of the vehicle height of a vehicle. [Background technology]

[0002] Conventionally, a suspension device that can adjust the vehicle height of a vehicle has been known, in which a damper mechanism that absorbs impacts from the road surface and an actuator mechanism that adjusts the vehicle height and controls the posture of the vehicle body are provided in parallel between the vehicle body and the wheels.For example, as shown in Patent Document 1, a suspension device that suspends each wheel from the vehicle body is known, in which a first actuator consisting of an air spring and a shock absorber and a second actuator consisting of an active actuator are arranged in parallel and are interposed between the suspension arm and the vehicle body.

[0003] In this suspension system, the first actuator functions as a suspension spring that absorbs shocks from the road surface and can adjust the vehicle height by controlling the stroke, while the second actuator can be used for vibration control to improve ride comfort by suppressing vertical vibrations on the spring caused by input from the road surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-37113 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, in a conventional suspension device having a structure in which a damper mechanism D and an actuator mechanism A are arranged in parallel as shown in Figure 7, when the actuator mechanism A is expanded or contracted to its maximum or minimum extent, the height at which the damper mechanism D can absorb impact is reduced, making it impossible to adequately control vibrations and resulting in a poor ride comfort.

[0006] Furthermore, conventional suspension systems have the problem of consuming a lot of power because when adjusting vehicle height with actuator mechanism A, damper mechanism D must also be expanded and contracted at the same time. Furthermore, conventional suspension systems receive impacts from the road surface not only through damper mechanism D but also through actuator mechanism A, so the structure poses a risk of damage to actuator mechanism A, which does not have the function of absorbing impacts.

[0007] To solve the above problem, a suspension device with a structure in which the damper mechanism D and the actuator mechanism A are arranged in series can be considered. However, with this structure, the overall length of the suspension device becomes longer, as shown in FIG. 8.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a suspension device characterized by the arrangement of a damper mechanism that absorbs shocks from the road surface while driving, and an actuator mechanism with a vehicle height adjustment function, which can reduce the power consumption of the actuator mechanism and reduce the risk of damage without increasing the size of the suspension device. [Means for solving the problem]

[0009] The suspension device of the present invention, which solves the above-mentioned problems, comprises a nut member that is arranged to be freely rotatable around a rotation axis, and a shaft member that is formed in a cylindrical shape and has the nut member attached to its outer surface, the shaft member being supported so that it can freely move back and forth along the rotation axis in response to the rotation of the nut member, and a damper mechanism comprising a damper main body and a damper shaft being arranged inside the shaft member. [Effects of the Invention]

[0010] In the suspension device according to the present invention, the shaft member of the actuator mechanism is formed in a large-diameter cylindrical shape, and the damper mechanism is disposed inside the shaft member, so that the actuator mechanism and the damper mechanism can be disposed in series without increasing the size of the suspension device. As a result, the damper mechanism can appropriately control vibrations regardless of the operating state of the actuator mechanism, improving ride comfort. In addition, the power consumption of the actuator mechanism can be reduced, and the risk of damage can be reduced. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an example of an installation state of a suspension device according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a suspension device according to a first embodiment of the present invention. [Figure 3] 1 is a perspective view showing a suspension device according to an embodiment of the present invention; [Figure 4] FIG. 2 is a perspective view showing a nut member according to an embodiment of the present invention. [Figure 5] This is a reference diagram that explains how the vehicle height is adjusted by changing the angle of the lower arm relative to the vehicle body. [Figure 6] 1 is a cross-sectional view showing a state in which the damper mechanism according to the first embodiment of the present invention is oscillating. [Figure 7] FIG. 10 is a reference diagram showing a conventional suspension device having a structure in which a damper mechanism and an actuator mechanism are arranged in parallel. [Figure 8] FIG. 10 is a reference diagram showing a conventional suspension device having a structure in which a damper mechanism and an actuator mechanism are arranged in series. [Figure 9] FIG. 6 is a cross-sectional view showing a suspension device according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing a state in which a damper mechanism according to a second embodiment of the present invention is oscillating. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of a suspension device according to the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention according to each claim, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0013] [First embodiment] FIG. 1 is a perspective view showing an example of the mounting state of a suspension device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a suspension device according to a first embodiment of the present invention, FIG. 3 is a perspective view showing a suspension device according to an embodiment of the present invention, FIG. 4 is a perspective view showing a nut member according to an embodiment of the present invention, FIG. 5 is a reference diagram explaining how the angle of the lower arm relative to the vehicle body is changed to adjust the vehicle height, and FIG. 6 is a cross-sectional view showing a state in which the damper mechanism according to the first embodiment of the present invention oscillates.

[0014] As shown in FIG. 1 as an example, the suspension unit 1a according to this embodiment is disposed in correspondence with the front, rear, left, and right wheels 6 of a vehicle. The wheels 6 are attached to a vehicle body (not shown) via upper arms 4 and lower arms 5 so as to be movable up and down. The suspension unit 1a is attached between the lower arms 5 and the vehicle body, and absorbs vibrations and shocks input from the road surface while the vehicle is traveling, thereby ensuring traveling stability. Furthermore, when adjusting the vehicle height, the suspension unit 1a changes the angle of the lower arms 5 relative to the vehicle body, thereby changing the position of the wheels 6 relative to the vehicle body and adjusting the vehicle height. The suspension unit 1a includes a fork 2, a spring 3, a damper mechanism 10, and an actuator mechanism 40a.

[0015] The fork 2 is located at the bottom of the suspension device 1a. The fork 2 is formed so as to split into two in the longitudinal direction of the vehicle, and includes a mounting shaft that extends across the lower tip of the split fork. The fork 2 is attached to the lower arm 5 so as to be rotatable about the mounting shaft. In addition, the fork 2 is attached to the lower arm 5 via a bushing, for example. The bushing includes a member made of an elastic material and formed in a substantially cylindrical shape that corresponds to the mounting shaft of the fork 2. Therefore, the fork 2 is attached to the lower arm 5 elastically via the bushing.

[0016] The spring 3 is a compression coil spring disposed between the fork 2 and the actuator mechanism 40a. The spring 3 supports the vehicle weight, and the stiffness of the spring determines the amount of tilt of the vehicle body that occurs in the front, rear, left, and right directions while traveling. The spring 3 expands and contracts in response to unevenness in the road surface, keeping the wheel 6 from leaving the road surface.

[0017] The damper mechanism 10 suppresses the movement of the oscillating spring 3. As an example, the damper mechanism 10 is preferably a damper that uses a functional fluid such as a magnetorheological fluid and has a structure that allows the damping force to be controlled by an electromagnetic coil. The structure of such a damper mechanism 10 is not particularly limited, but may be, for example, the following structure.

[0018] 2, the damper mechanism 10 includes a damper body 20 that generates a damping force, and a damper shaft 30 that is disposed so as to vertically penetrate the damper body 20. The damper body 20 is formed in a substantially cylindrical shape, and the damper shaft 30 is disposed coaxially with the damper body 20.

[0019] The damper shaft 30 has its lower end connected to the fork 2, and reciprocates in the axial direction in conjunction with the up-and-down movement of the lower arm 5. On the outer periphery of the damper shaft 30, there are formed spline grooves 32 that engage with a linear engagement portion 24 (described later) and extend along the axial direction, and a spiral rolling element rolling groove 31 that threadably engages with a rotational engagement portion 23 (described later).

[0020] The linear motion engagement portion 24 is attached to the damper body 20 and supports the damper shaft 30 movably along the axial direction. The linear motion engagement portion 24 preferably has a loaded rolling element rolling groove 24a that corresponds to the spline groove 32 of the damper shaft 30.

[0021] Preferably, a plurality of rolling elements 24b are disposed between the loaded rolling element rolling groove 24a and the spline groove 32, and the damper shaft 30 is supported by the linear engagement portion 24 via the rolling elements 24b that roll between the loaded rolling element rolling groove 24a and the spline groove 32. For example, steel balls are preferably used as the rolling elements 24b.

[0022] The rotational engagement portion 23 is threadedly engaged with the damper shaft 30 and is attached so as to be rotatable around the axis of the damper shaft 30 in accordance with the axial reciprocating motion of the damper shaft 30. The rotational engagement portion 23 preferably has a loaded rolling element rolling groove 23a that corresponds to the rolling element rolling groove 31 of the damper shaft 30.

[0023] Preferably, a plurality of rolling elements 23b are disposed between the loaded rolling element rolling groove 23a and the rolling element rolling groove 31, and the rotational engagement portion 23 is screwed onto the damper shaft 30 via the rolling elements 23b that roll between the loaded rolling element rolling groove 23a and the rolling element rolling groove 31. Preferably, the rolling elements 23b are, for example, steel balls.

[0024] Furthermore, the rotational engagement portion 23 has a rotational resistance portion (not shown) that rotates in a functional fluid filled in a predetermined space formed in the damper body 20. The functional fluid will be described later.

[0025] The damper body 20 is formed in a substantially cylindrical shape and includes an electromagnetic section (not shown) that is made up of an electromagnetic coil and a magnetic path forming member. The electromagnetic coil is formed by winding conductive wire around the axis of the damper body 20, and generates a magnetic field in the surrounding area in response to an applied voltage. The magnetic path forming member is made of a magnetic material, such as an iron-based material, and forms a magnetic flux loop due to the magnetic field generated when current is passed through the electromagnetic coil. The damper body 20 also has a predetermined space (not shown) that is arranged to cross the magnetic flux loop formed by the electromagnetic section, and this space is filled with a functional fluid.

[0026] Examples of functional fluids include magnetic fluids, which are made by dispersing ferromagnetic particles such as iron powder in a liquid such as oil, and magnetorheological fluids (MR fluids). When not subjected to a magnetic field, functional fluids behave similarly to ordinary hydraulic oils. When an external magnetic field is applied, the ferromagnetic particles uniformly dispersed in the liquid link together along the direction of the magnetic field, forming chain-like clusters. These clusters resist flow, increasing the apparent viscosity of the functional fluid. This change in viscosity due to a magnetic field is reversible, and the original state can be restored by removing the magnetic field. Furthermore, the degree of viscosity change can be adjusted by changing the strength of the magnetic field.

[0027] A rotational resistance portion of the rotational engagement portion 23 is disposed in the space filled with the functional fluid. When the rotational engagement portion 23 rotates in accordance with the axial reciprocating motion of the damper shaft 30, the rotational resistance portion rotates within the space filled with the functional fluid. At this time, when a voltage is applied to the electromagnetic coil and the apparent viscosity of the functional fluid increases, shear resistance is generated between the functional fluid and the rotational resistance portion.

[0028] That is, with this damper mechanism 10, the apparent viscosity of the functional fluid can be adjusted by controlling the voltage applied to the electromagnetic coil, thereby obtaining damping characteristics as required.

[0029] In this embodiment, the damper mechanism 10 is not limited to this structure, and may have a structure in which a damping force is generated by hydraulic oil filled inside the damper body and a piston that can move back and forth within the hydraulic oil.

[0030] 2 and 3, the actuator mechanism 40a is configured, for example, with an actuator main body 41 attached to the vehicle body, and a shaft member 70 supported so as to be movable in the up and down direction relative to the actuator main body 41. The actuator mechanism 40a changes the amount of up and down stroke of the shaft member 70 relative to the actuator main body 41, thereby changing the angle of the lower arm 5 relative to the vehicle body and adjusting the height of the vehicle body from the ground.

[0031] The actuator body 41 includes a drive unit 50 that generates power, and a nut member 60 that is disposed so as to surround the outer surface of the shaft member 70 .

[0032] The drive device 50 includes, for example, a motor 51 controlled by a signal from a control system or the like provided in the vehicle, a gear 52 that transmits the power of the motor 51 to the nut member 60, and a non-excitation brake 53.

[0033] The non-excitation brake 53 can have a conventionally known structure and suppresses rotation of the gear 52 when the voltage applied to the motor 51 is cut off. By suppressing rotation of the gear 52, the nut member 60 becomes unable to rotate, thereby stopping the vertical movement of the shaft member 70. In this way, the non-excitation brake 53 prevents changes in the vertical stroke amount of the shaft member 70 even when the power supply to the motor 51 is cut off, and can prevent a drop in vehicle height due to its own weight.

[0034] As shown in Fig. 4, the nut member 60 is formed in a low, approximately cylindrical shape and is provided with a bearing portion 61 and a gear portion 62 on its outer surface. The bearing portion 61 rotatably supports the nut member 60 relative to the actuator body 41. The gear portion 62 engages with the gear 52 of the drive unit 50 and rotates the nut member 60 about its axis in response to rotation of the motor 51. Note that the nut member 60 will be described as being formed in a low, approximately cylindrical shape, but the shape of the nut member 60 is not limited to this. As long as a loaded rolling element rolling groove 63 (described later) is formed on the inner surface and the bearing portion 61 and the gear portion 62 are provided on the outer surface, the nut member 60 does not necessarily have to have a substantially cylindrical outer shape.

[0035] A loaded rolling element rolling groove 63 is formed on the inner surface of the nut member 60, which corresponds to the spiral rolling element rolling groove 71 formed on the outer surface of the shaft member 70. In addition, a plurality of rolling elements 42 are arranged between the loaded rolling element rolling groove 63 and the rolling element rolling groove 71.

[0036] The nut member 60 is threadedly engaged with the shaft member 70 via the rolling elements 42 that roll between the loaded rolling element rolling grooves 63 and the rolling element rolling grooves 71. The nut member 60 supports the shaft member 70 so that it can reciprocate axially in response to rotation of the nut member 60 about its axis. Steel balls, for example, are suitably used as the rolling elements 42.

[0037] The loaded rolling element rolling groove 63 is formed to correspond to one turn of the spirally formed rolling element rolling groove 71. The loaded rolling element rolling groove 63 also has a continuous portion 64 formed to connect one turn of the spiral in the height direction, forming a groove that circulates around the inner surface of the nut member 60.

[0038] Furthermore, it is preferable that the loaded rolling element rolling groove 63 is formed as a groove having an arc-shaped cross section corresponding to the spherical diameter of the rolling elements 42. It is also preferable that the continuous portion 64 is formed to have a deeper groove depth than the loaded rolling element rolling groove 63 of the spiral portion. Such a continuous portion 64 can prevent interference between the rolling elements 42 located in the continuous portion 64 and the shaft member 70, even when the nut member 60 and the shaft member 70 are screwed together. Therefore, the rolling elements 42 can circulate smoothly between the rolling element rolling groove 71 and the loaded rolling element rolling groove 63, and rotation of the nut member 60 can cause the shaft member 70 to smoothly reciprocate in the axial direction.

[0039] Furthermore, it is preferable that a male thread-like projection 65 extending along the spiral direction of the loaded rolling element rolling groove 63 is formed in the vertical direction of the continuous portion 64. The male thread-like projection 65 engages with the rolling element rolling groove 71 of the shaft member 70, and serves as a guide for ensuring that the nut member 60 and the shaft member 70 are screwed together when the nut member 60 rotates around its axis.

[0040] As shown in Fig. 2, the shaft member 70 is formed in a cylindrical shape with a large diameter. Furthermore, the outer surface of the shaft member 70 is provided with a spiral rolling element rolling groove 71 and a plurality of spline grooves 72 extending along the axial direction, as shown in Fig. 3. Note that, although the shaft member 70 will be described as being formed in a cylindrical shape with a large diameter, the shape of the shaft member 70 is not limited to this. It is sufficient that the shaft member 70 is formed in a cylindrical shape, is provided with the rolling element rolling grooves 71 and the spline grooves 72, and has a space formed therein in which the damper main body 20 can be disposed, as will be described later, and the external appearance does not have to be formed in a cylindrical shape.

[0041] The number of spiral turns of the rolling element rolling groove 71 and the installation range in the height direction are set to correspond to the vehicle height adjustment amount by the actuator mechanism 40a. In addition, the rolling element rolling groove 71 is formed into a groove having an arc-shaped cross section corresponding to the spherical diameter of the rolling element 42.

[0042] As an example, the spline grooves 72 are preferably formed in a set of two spline grooves 72 arranged adjacent to each other in parallel, with a plurality of such sets being formed in the circumferential direction of the shaft member 70. As an example, the spline grooves 72 are preferably grooves having a substantially triangular cross section and formed to have a shallower groove depth than the rolling element rolling grooves 71.

[0043] 3, the actuator body 41 is provided with a rotation prevention portion 43 that corresponds to the spline groove 72. The rotation prevention portion 43 engages with the spline groove 72 and supports the shaft member 70 so that it cannot rotate about its axis but can move in the axial direction.

[0044] As shown in Fig. 2, the damper body 20 is disposed inside the shaft member 70, which is formed in a cylindrical shape with a large diameter. The damper body 20 is preferably disposed at a height that overlaps with the nut member 60 that threads onto the shaft member 70. By disposing the damper body 20 in this manner, it is possible to reduce the overall length of the suspension device 1a.

[0045] As shown in FIG. 2 , a gap S is formed between the outer surface of the damper main body 20 and the inner surface of the shaft member 70. The damper main body 20 is attached to the shaft member 70 via an upper mount 11, which will be described later, so as to be able to swing freely in the axial direction of the shaft member 70. The gap S is formed to an appropriate size so that the outer surface of the damper main body 20 and the inner surface of the shaft member 70 do not interfere with each other even when the damper main body 20 swings. Therefore, even when the damper main body 20 swings to the maximum extent, a minimum distance is maintained between the outer surface of the damper main body 20 and the inner surface of the shaft member 70. Furthermore, when the shaft member 70 is formed in a substantially cylindrical shape and the interior of the shaft member 70 is formed to have a circular cross section, as in this embodiment, it is preferable that the gap S be formed around the entire radial circumference of the shaft member 70.

[0046] The upper mount 11 is disposed on top of the shaft member 70 and supports the damper body 20. The upper mount 11 is made of an elastic material. Such an upper mount 11 can support the damper body 20 so that it can swing freely in the axial direction of the shaft member 70. Vibrations from the road surface are input to the upper mount 11 via the damper body 20. At this time, the upper mount 11, which is made of an elastic material, can control the vibrations together with the operation of the damper mechanism 10, thereby improving the ride comfort for the driver and passengers.

[0047] Such an actuator mechanism 40a can adjust the vehicle height by the operation described below.

[0048] When a motor 51 of a drive unit 50 is rotated by a signal from a control system or the like provided in a vehicle, a gear 52 connected to the output shaft of the motor 51 rotates. The gear 52 is engaged with a gear portion 62 of a nut member 60, causing the nut member 60 to rotate.

[0049] The shaft member 70 that screws into the nut member 60 is supported so as to be non-rotatable but movable in the axial direction by the engagement between the spline grooves 72 and the anti-rotation portion 43. Therefore, the shaft member 70 moves in the axial direction relative to the actuator body 41 in response to the rotation of the nut member 60. At this time, the damper mechanism 10, the spring 3, and the fork 2 move in the axial direction together with the shaft member 70.

[0050] The actuator body 41 is attached to the vehicle body, and the fork 2 moves axially together with the shaft member 70 as described above. Therefore, the distance between the vehicle body and the lower end of the fork 2 changes due to the axial movement of the shaft member 70, and the lower arm 5 connected to the fork 2 changes its angle relative to the vehicle body. This changes the position of the wheel 6 relative to the vehicle body, making it possible to adjust the vehicle height.

[0051] As described above, according to suspension unit 1a of the present embodiment, shaft member 70 of actuator mechanism 40a, which has a vehicle height adjustment function, is formed into a large-diameter cylinder, and damper mechanism 10 is disposed inside this, so that damper mechanism 10 and actuator mechanism 40a can be disposed in series without increasing the size of suspension unit 1a. As a result, vibrations can be appropriately controlled by damper mechanism 10 without being restricted by the expansion / contraction state of actuator mechanism 40a, and the ride comfort of the driver and passengers can be improved.

[0052] Furthermore, with the suspension device 1a of this embodiment, when adjusting the vehicle height, there is no need to expand and contract the damper mechanism 10 simultaneously with the actuator mechanism 40a, thereby reducing power consumption. Furthermore, with the suspension device 1a of this embodiment, impacts from the road surface are not directly transmitted to the actuator mechanism 40a, and the load is damped by the spring 3 and the damper mechanism 10 and input to the actuator mechanism 40a. This reduces the load input to the actuator mechanism 40a, reducing the risk of damage.

[0053] Furthermore, the actuator mechanism 40a in this embodiment has a structure in which the nut member 60 is threadedly engaged with the shaft member 70 via the rolling elements 42. The actuator mechanism 40a having such a structure is characterized by not only high efficiency in converting the rotational motion of the nut member 60 into linear motion in the axial direction of the shaft member 70, but also high inverse efficiency in converting the linear motion of the shaft member 70 into rotational motion around the axis of the nut member 60. Therefore, when the shaft member 70 moves axially due to a load input to the actuator mechanism 40a in response to unevenness in the road surface, the nut member 60 can be efficiently rotated around the axis. The rotational motion of the nut member 60 can rotate the motor 51 via the gear 52, allowing the motor 51 to function as a generator.

[0054] As described above, according to the suspension device 1a of this embodiment, the load input to the actuator mechanism 40a from unevenness in the road surface can be used to efficiently rotate the nut member 60, allowing the motor 51 to generate regenerative power. Furthermore, the generated regenerative power can be used, for example, to charge the power supply device or as a voltage to be applied to the electromagnetic coil of the damper body 20.

[0055] As described above, suspension device 1a according to this embodiment has damper mechanism 10 and actuator mechanism 40 arranged in series, and is therefore able to generate regenerative current more efficiently than conventional suspension devices in which the damper mechanism and actuator mechanism are arranged in parallel. This is because, when the damper mechanism and actuator mechanism are arranged in parallel, the expansion and contraction of the damper mechanism creates resistance when the actuator mechanism receives force from the road surface and operates, making it difficult to efficiently convert input from the road surface into regenerative current. However, when damper mechanism 10 and actuator mechanism 40 are arranged in series, as in suspension device 1a according to this embodiment, it is possible to convert input from the road surface into regenerative current without being affected by the expansion and contraction of damper mechanism 10.

[0056] With this method of adjusting vehicle height, the lower end of fork 2 moves in an arc around the mounting portion of lower arm 5 on the vehicle body side as the center of rotation, as shown in Figure 5. In this case, with a conventional suspension device, the mounting angle of the suspension device attached to the vehicle body does not change, so correction according to the angle after vehicle height adjustment cannot be made, and impacts from the road surface may not be properly absorbed along the axial direction of the damper shaft.

[0057] 6, in the suspension device 1a according to this embodiment, the damper body 20 is attached via the upper mount 11 so as to be able to swing freely relative to the shaft member 70 and the actuator body 41. Furthermore, because a gap S of an appropriate size is formed between the outer surface of the damper body 20 and the inner surface of the shaft member 70 as described above, the damper body 20 and the shaft member 70 will not interfere with each other even if the damper body 20 is tilted.

[0058] Thus, according to the suspension device 1a of this embodiment, the damper body 20 and the damper shaft 30 are tilted at an appropriate angle depending on the position of the fork 2 after vehicle height adjustment, and impacts from the road surface can be appropriately absorbed along the axial direction of the damper shaft 30.

[0059] [Second embodiment] In the suspension device 1a according to the first embodiment described above, the shaft member 70 is formed in a large-diameter cylindrical shape, and the damper body 20 is disposed inside the shaft member 70. The damper mechanism 10 is supported so as to be able to swing freely around the end of the damper body 20 via an upper mount 11 disposed on the upper part of the shaft member 70. Next, a suspension device 1b according to a second embodiment will be described, which has a different configuration from that of the first embodiment. Note that components that are the same as or similar to those in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

[0060] FIG. 9 is a cross-sectional view showing a suspension device according to a second embodiment of the present invention, and FIG. 10 is a cross-sectional view showing a state in which the damper mechanism according to the second embodiment of the present invention is oscillating.

[0061] Similar to the suspension unit 1a according to the first embodiment, the suspension unit 1b according to this embodiment is attached between the lower arm 5 and the vehicle body in correspondence with the front, rear, left and right wheels 6 of the vehicle. The suspension unit 1b also includes a fork 2, a spring 3, a damper mechanism 10, and an actuator mechanism 40b.

[0062] As an example, the actuator mechanism 40b is configured by an actuator body 41 fixed to the vehicle body, and a shaft member 80 supported relative to the actuator body 41 so as to be movable in the up and down direction, as shown in FIG.

[0063] As shown in Fig. 9, the shaft member 80 is formed in a large-diameter cylindrical shape. The outer surface of the shaft member 80 is provided with a spiral rolling element rolling groove 71 and a plurality of spline grooves extending along the axial direction, similar to the shaft member 70 according to the first embodiment. A plate 81 is disposed at the lower end of the shaft member 80, and the shaft member 80 is supported by a spring 3 via the plate 81.

[0064] 9, plate 81 is disposed so as to cover the lower end of shaft member 80, which is formed in a cylindrical shape. Upper mount 12 is placed on the upper surface of plate 81, and the upper end surface of spring 3 abuts on the lower surface. In addition, as one example, plate 81 is formed with a through hole 82, through which damper shaft 30 passes, at a position corresponding to the axis of shaft member 80. A predetermined gap is secured between through hole 82 and damper shaft 30 to prevent interference due to swinging of damper shaft 30.

[0065] As shown in FIG. 9 , the upper mount 12 is disposed at a position corresponding to the axis of the shaft member 80. The upper mount 12 is disposed near the upper end of the spring 3 by abutting against the upper surface of a plate 81. The upper mount 12 is made of an elastic material, for example, and supports the damper mechanism 10 so that it can swing freely. In this embodiment, the upper mount 12 supports the upper end of the damper shaft 30. The upper mount 12 is held so that its periphery is surrounded by a fixing block 83, and is fixed in a predetermined position.

[0066] In the damper mechanism 10 according to this embodiment, the upper end of the damper shaft 30 is supported by the upper mount 12 so as to be able to swing freely. The damper shaft 30 extends along the axial direction of the spring 3 so as to penetrate the inside of the spring 3, and the damper main body 20 is disposed at the lower end of the damper shaft 30, as shown in Fig. 10 . Note that the arrangement of the components that constitute the damper mechanism 10 is not limited to this, and if the inner diameter of the spring 3 is large, the upper mount 12 may support the upper end of the damper main body 20, and the damper shaft 30 may be disposed so as to extend downward from the damper main body 20.

[0067] With this arrangement of the upper mount 12 and the damper mechanism 10, the oscillation center of the damper mechanism 10 is located along the axis of the shaft member 80 and is set at a height near the upper end of the spring 3. This allows the oscillation center of the damper mechanism 10 and the upper end surface of the spring, which is the oscillation center of the spring 3, to be positioned close to each other.

[0068] 9, the plate 81 according to this embodiment may have a shape that has a recess in the center so that the height of the top surface on which the upper mount 12 is placed is lower than the height of the bottom surface that abuts against the upper end surface of the spring 3. With such a plate 81, the positional relationship between the oscillation center of the damper mechanism 10 and the upper end surface of the spring, which is the oscillation center of the spring 3, can be matched.

[0069] As described above, when adjusting the vehicle height, the lower end of the fork 2 moves in an arc around the mounting portion of the lower arm 5 on the vehicle body side as the center of rotation. In the suspension device 1b according to this embodiment, the damper mechanism 10 tilts at an appropriate angle depending on the position of the fork 2 after adjusting the vehicle height, thereby enabling shocks from the road surface to be appropriately absorbed along the axial direction of the damper shaft 30. At this time, the spring 3 also swings around its upper end face as the center, and the angle of its axis tilts.

[0070] If there is a large misalignment between the oscillation center of the spring 3 and the oscillation center of the damper mechanism 10, misalignment occurs between the axis of the spring 3 and the axis of the damper mechanism 10, and the degree of misalignment increases. As the misalignment increases, it becomes necessary to provide larger gaps between the components to prevent interference between them. Furthermore, if there are restrictions on the dimensions of the components due to the surrounding structure of the suspension device or the installation environment, it may not be possible to ensure an appropriate gap, and the oscillation angle may have to be limited to prevent interference between the components.

[0071] In the suspension unit 1b according to this embodiment, the oscillation center of the spring 3 and the oscillation center of the damper mechanism 10 can be positioned close to or aligned with each other. This makes it possible to suppress misalignment between the axis of the spring 3 and the axis of the damper mechanism 10 during oscillation, thereby reducing the gaps required between the damper mechanism 10 and each component. As a result, the entire suspension unit 1b can be made smaller, and the angular range over which it can oscillate freely without interference can be expanded.

[0072] The oscillation angle of the damper mechanism 10 depends on the range of vertical movement of the vehicle body and the structure of the entire suspension device. Furthermore, the gap between the damper mechanism 10 and each component depends on the dimensions of each component of the damper mechanism 10 and the dimensions of the spring 3, etc. For this reason, it is preferable to determine the distance between the oscillation center of the damper mechanism 10 and the oscillation center of the spring 3 with reference to the dimensions of each component of the damper mechanism 10 and the spring 3, etc. Furthermore, it is generally considered preferable to ensure a gap of 10 mm or more between each component when the damper mechanism is oscillating.

[0073] As an example, the suspension device 1b of this embodiment can ensure a minimum gap of 10 mm or more between the damper mechanism 10 and each component when the damper mechanism 10 oscillates by setting the range of up and down movement of the damper mechanism 10 to ±60 mm and the distance between the centers of oscillation of the damper mechanism 10 and the spring 3 to 21.5 mm.

[0074] While the suspension devices 1a and 1b according to the present invention have been described as having a structure in which the power of the motor 51 is transmitted to the nut member 60 via the gear 52 to rotate the nut member 60, the structure for rotating the nut member 60 is not limited to this, and a structure in which the nut member 60 is directly rotated by a hollow motor may also be used. Furthermore, the suspension device 1a according to the present invention has been described as being mounted on a vehicle in which a driver rides, such as a passenger car or truck, but this is not a limitation, and the device may also be applied to vehicles such as delivery robots that are operated from the outside without a driver on board. It is clear from the claims that such modified or improved embodiments are also included within the technical scope of the present invention. [Explanation of symbols]

[0075] 1a, 1b suspension device, 3 spring, 10 damper mechanism, 11, 12 upper mount, 20 damper body, 30 damper shaft, 43 anti-rotation portion, 51 motor, 60 nut member, 63 load rolling element rolling groove, 70, 80 shaft member, 71 rolling element rolling groove, 72 spline groove, S gap.

Claims

1. a nut member arranged to be rotatable about a rotation axis; a shaft member formed in a cylindrical shape and having the nut member assembled to its outer surface, the shaft member is supported so as to be capable of reciprocating along the rotation axis in response to rotation of the nut member, A suspension device characterized in that a damper mechanism including a damper body and a damper shaft is disposed inside the shaft member.

2. 2. The suspension device according to claim 1, The suspension device is characterized in that the damper body is attached to the rotation shaft so as to be able to swing freely.

3. 2. The suspension device according to claim 1, A suspension device according to claim 1, wherein a gap is formed between an outer surface of the damper body and an inner surface of the shaft member.

4. 2. The suspension device according to claim 1, A spiral rolling element rolling groove is formed on the outer surface of the shaft member, A loaded rolling element rolling groove corresponding to the rolling element rolling groove is formed on the inner surface of the nut member, a plurality of rolling elements are rollably disposed between the rolling element rolling groove and the loaded rolling element rolling groove; The suspension device according to claim 1, wherein the shaft member is threadedly engaged with the nut member via the rolling elements.

5. 2. The suspension device according to claim 1, a spline groove extending along the rotation axis is formed on the outer surface of the shaft member; a rotation prevention portion that engages with the spline groove and supports the shaft member so as to be unable to rotate around the rotation axis but movably along the rotation axis;

6. 2. The suspension device according to claim 1, The damper body comprises an electromagnetic part that forms a magnetic flux loop and a functional fluid whose apparent viscosity can be adjusted by a magnetic field, and the damping force can be adjusted by controlling the voltage applied to the electromagnetic part.

7. 2. The suspension device according to claim 1, The suspension device is characterized in that the nut member is connected to a motor.

8. 2. The suspension device according to claim 1, The shaft member is supported by a spring, the damper mechanism is attached to the rotation shaft so as to be swingable with respect to the rotation shaft, A suspension device according to claim 1, wherein the center of oscillation of the damper mechanism is located near the upper end of the spring.

9. 9. The suspension device according to claim 8, The suspension device is characterized in that the damper mechanism is attached so as to be swingable around an end of the damper body.

10. 9. The suspension device according to claim 8, The suspension device is characterized in that the damper mechanism is attached so as to be swingable around the end of the damper shaft.

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