Active suspension

Abstract

To provide an active suspension including a compact torsion spring while securing an effective length.SOLUTION: An active suspension A includes a motor M including a rotor m1 having a hollow rotor shaft m2, a housing H internally housing the motor M, an output part g1 provided concentrically with an axial center X of the rotor m1 and adapted to be rotated by receiving the rotation of the rotor m1, a cylindrical first torsion spring S1 to which the rotation is transmitted from the output part g1, and a second torsion spring S2 where one end of itself and the end of the first torsion spring S1 are fixed around the axial center X in a relatively non-rotatable manner and the other end of itself extends to an action object, in a state of being inserted into the rotor shaft m2 and the first torsion spring S1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an active suspension in which a torsion spring connected in multiple stages is integral with a motor. [Background technology]

[0002] Conventionally, such an active suspension is disclosed, for example, in Patent Document 1 (see

[0004] to

[0005] and Figs. 1, 3 and 4).

[0003] In a conventional active suspension, a suspension spring, a hydraulic shock absorber, and an approach / separation force generator are disposed between the sprung and unsprung members. The approach / separation force generator includes an elastic body and an electromagnetic actuator 26. The force exerted by the electromagnetic actuator 26 acts as an approach / separation force that damps vibration between the vehicle body and the wheels via the elastic body.

[0004] In this conventional suspension, by generating a damping force from the approach / separation force generator in addition to the damping force from the shock absorber at each wheel, it is possible to suppress roll when the vehicle is cornering. By controlling the approach / separation force generator, it is possible to suitably change the vibration damping characteristics, which improves the practicality of the vehicle suspension system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-55944 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned conventional active suspension, a shaft portion 60, which is a torsion spring, extends from an electromagnetic actuator 26 constructed using a motor, and an arm portion 62 attached to the end of the shaft portion 60 pushes and pulls a link rod 32. This applies a damping force to a lower arm 46 of the suspension. A coil spring 51 and a shock absorber 52 are separately attached to the lower arm 46, and the operation of the suspension is controlled by driving the electromagnetic actuator 26.

[0007] According to this configuration, the shaft portion 60 serving as a torsion spring is provided between the electromagnetic actuator 26 and the arm portion 62. However, in consideration of the size of the installation space for this configuration, the shaft portion 60 is limited to a predetermined length, and therefore the shaft portion 60 may not be able to exhibit the desired torsional characteristics. For example, the rigidity of the shaft portion 60 becomes excessively high, which tends to result in a stiff suspension. In addition, stress is likely to be concentrated at a specific point of the shaft portion 60, which may impair the durability of the shaft portion 60.

[0008] As described above, conventional active suspensions have various problems to be solved in terms of their configuration and installation space, and there has been a demand for an active suspension equipped with a compact torsion spring while ensuring an effective length. [Means for solving the problem]

[0009] (Features) The characteristic configuration of the active suspension according to the present invention is as follows: a motor including a rotor having a hollow rotor shaft; a housing that houses the motor; an output section that is provided coaxially with an axis of the rotor and rotates in response to the rotation of the rotor; a cylindrical first torsion spring to which rotation from the output portion is transmitted; a second torsion spring, one end of which is fixed to an end of the first torsion spring so as not to rotate relatively around the axis when inserted into the rotor shaft and the first torsion spring, and the other end of which extends toward an object to be acted upon; The point is that it is equipped with the following features.

[0010] (effect) In this configuration, the first torsion spring and the second torsion spring have a double structure, the end of the first torsion spring is connected to the output section, and the end of the second torsion spring is extended to the target on which it acts, making it possible to obtain a compact torsion spring with a short overall length while ensuring the effective length of the torsion spring.

[0011] Furthermore, since the second torsion spring passes through the hollow rotor shaft, the installation area of ​​the housing and the installation area of ​​the second torsion spring overlap, making the entire device more compact.

[0012] With this configuration, the setting range of the spring constant of the torsion spring is expanded, and there is no need to prepare a separate spring element to obtain the desired spring constant for the entire suspension, making it possible to obtain an active suspension with a rational configuration with a reduced number of parts.

[0013] (Features) In the active suspension according to the present invention, it is advantageous if at least one bearing for supporting the second torsion spring is provided in the housing.

[0014] (effect) By supporting the second torsion spring together with the rotor in the same housing as in this configuration, the axis of the rotor and the axis of the second torsion spring are precisely aligned. Therefore, even if the second torsion spring penetrates the inside of the rotor, interference between the two is unlikely to occur, and the rotational drive of the motor can be efficiently transmitted to the second torsion spring.

[0015] (Features) In the active suspension according to the present invention, it is advantageous if the first torsion spring and the second torsion spring are fixed together by a spline connection, the first torsion spring and the output section are connected on one side of the motor, and the bearing of the second torsion spring is provided on the other side of the motor.

[0016] (effect) If the first torsion spring and the second torsion spring are fixed to each other by a spline connection, the fitting contact between the two springs is performed in a predetermined area along the longitudinal direction, which makes it difficult for axial runout to occur between the two springs.

[0017] In addition, because the connection position of the first torsion spring and the support position of the second torsion spring in the housing are spaced apart on opposite sides of the motor, the fixed state of both integrated torsion springs to the housing is stabilized, making it even more difficult for interference to occur between the first torsion spring and the second torsion spring during torsional motion of the torsion spring, and providing an active suspension that reliably exhibits the desired spring characteristics.

[0018] (Features) In the active suspension of the present invention, at the spline connection portion, a bottom portion having a hole portion is formed at the end of the first torsion spring, and a female thread portion is formed on the end face of the second torsion spring, and the relative position of the first torsion spring and the second torsion spring can be adjusted depending on the amount of tightening of a male thread member inserted into the bottom portion from outside the hole portion.

[0019] (effect) If the amount of retraction of the second torsion spring relative to the bottom of the first torsion spring can be arbitrarily adjusted by adjusting the amount of tightening of the male screw member as in this configuration, the installation positions of the first torsion spring and the second torsion spring can be optimized. For example, if one end of the first torsion spring is connected to the output part and the end of the second torsion spring is spline-coupled to the other end, the position of the other end of the second torsion spring can be changed according to the tightening of the male screw member.

[0020] Therefore, even if there is an error in the installation position of the bearing of the second torsion spring relative to the housing, the support position of the second torsion spring can be accurately aligned by the above adjustment.

[0021] This configuration is also effective when there are restrictions on the connection position between the end of the second torsion spring and the object on which it acts. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view showing an example of an arrangement of an active suspension according to a first embodiment; [Diagram 2] FIG. 1 is a cross-sectional view showing a structure of an active suspension according to a first embodiment. [Diagram 3] FIG. 1 is an exploded perspective view showing a configuration of an active suspension according to a first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] [First embodiment] (overview) A first embodiment of an active suspension A according to the present invention is shown in Figures 1 to 3. Figure 1 shows an example of the layout of the active suspension, and Figures 2 and 3 show the structure of the active suspension. In particular, Figure 3 shows only the main components.

[0024] This active suspension A applies a rotational force to an arm member that constitutes the suspension of a vehicle 1, reducing rolling when the vehicle 1 turns and pitching when going over an uneven road surface, as shown in Fig. 1. Although Fig. 1 only shows the arm member of the suspension, a coil spring or shock absorber (not shown) may be attached to the arm member.

[0025] As shown in Figures 2 and 3, this active suspension A is equipped with a motor M inside a housing H, and the rotational drive of this motor M is transmitted to a torsion spring S to control the operation of the suspension. In particular, the torsion spring S has a double tube structure, and a part of the torsion spring S passes through the rotor shaft m2 of the rotor m1. With this configuration, it is possible to obtain an extremely compact active suspension A that exhibits a desired spring constant. Each part will be described in detail below.

[0026] [Motor] A motor M equipped with a stator m3 and a rotor m1 is disposed in the approximate center of a housing H. In this embodiment, the rotor shaft m2 in particular is configured to be cylindrical. The rotor shaft m2 protrudes on both sides of the rotor m1, and each end is supported at both ends by the housing H via a first rotor bearing b1 and a second rotor bearing b2 equipped with bearings.

[0027] A reducer G, which will be described later, is connected to one end of the rotor shaft m2, and the rotation speed of the rotor m1 is reduced and transmitted to the torsion spring S. As the rotation speed is reduced, a rotational driving force with a strong torque is transmitted to the torsion spring S.

[0028] The driving rotation that has passed through the reducer G is transmitted to a torsion spring S from an output part g1 provided in the reducer G. In this embodiment, the rotor shaft m2 and the output part g1 are configured to have a common axis X.

[0029] A control plate C is provided in the housing H adjacent to the stator m3 of the motor M. In the control plate C, for example, the amount of sagging of the outside of the vehicle 1 during turning is calculated based on a signal from the control unit 3, that is, a signal obtained by processing detection values ​​from the lateral G sensor 2a and the steering angle sensor 2b provided at predetermined positions of the vehicle 1 by the control unit 3. Based on the calculated value of the amount of sagging, the motor M is driven to rotate over a predetermined angle, and a desired rotation angle is obtained at the output unit g1 via the reduction gear G. As a result, an external force is applied to the suspension, and the inclination of the vehicle 1 during turning is appropriately controlled.

[0030] Furthermore, when the active suspension A is provided on all four wheels of the vehicle 1, for example, by simultaneously driving the two front wheels or the two rear wheels, it is possible to suppress pitching changes of the vehicle 1 when going over an uneven road surface.

[0031] [Reduction gear] In this embodiment, for example, a strain wave gear mechanism capable of obtaining a large reduction ratio is used as the reducer G. As shown in Fig. 3, the strain wave gear mechanism is composed of a rotating member g2 connected to the rotor shaft m2, a cylindrical external gear g3 whose overall shape is elastically deformed when pressed radially outward by the rotating member g2, and an internal gear g4 fixed to the housing H so that some of the teeth of the external gear g3 mesh with it.

[0032] One end of the rotating member g2 is splined to the rotor shaft m2, and the other end is provided with a pair of pressing parts g2a having a predetermined radius in the radial direction. The pressing parts g2a are, for example, roller members that rotate relative to the rotating member g2, and locally press the inner surface of the external gear g3 to elastically deform the external gear g3 outward in the radial direction.

[0033] A certain number of external teeth of a portion of the external gear g3 that has been pressed to expand its diameter mesh with the internal gear g4. The internal gear g4 is a cylindrical member fixed to the housing H and does not elastically deform. The total number of teeth of the external gear g3 is a certain number less than the total number of teeth of the internal gear g4. Therefore, as the external gear g3 rotates, the meshing combination between the external teeth of the external gear g3 and the internal teeth of the internal gear g4 changes sequentially, and the external gear g3 rotates relative to the internal gear g4, thereby decelerating.

[0034] 2 and 3, the external gear g3 is configured in a cylindrical shape and is formed integrally with the external gear g3, and an output portion g1 located at an end farther from the motor M is spline-connected to a first torsion spring S1 (hereinafter, abbreviated as "first spring S1") described below. This ensures that the rotational drive of the external gear g3 is transmitted to the first spring S1.

[0035] [Torsion spring] 2 and 3, the first spring S1 connected to the reducer G has a cylindrical configuration. A solid second torsion spring S2 (hereinafter, abbreviated as "second spring S2") is inserted inside the first spring S1.

[0036] An end of the first spring S1 and an end of the second spring S2 are also connected by a spline connection. This spline connection has a predetermined length along the axis X, so the relative posture of the two springs is stable with their axes X well aligned. Furthermore, the output part g1 of the external gear g3 is journaled on the housing H by the first spring receiver B1 using a large bearing. Therefore, the first spring S1 rotates extremely smoothly and can rotate with little deflection around the axis X.

[0037] A second spring S2 is connected to the other end of the first spring S1 in an inserted state. This portion is also splined. The second spring S2 not only passes through the first spring S1, but also passes through the rotor shaft m2 of the motor M and protrudes to the opposite side of the motor M. The portion near the protruding end is journaled to the housing H by a second spring retainer B2 equipped with a rolling roller.

[0038] The connection between the first spring S1 and the second spring S2 may be a spline connection or a serration connection. Both are coaxial mechanical elements that transmit torque by simultaneously engaging equally spaced teeth on the outer periphery of a cylindrical shaft with matching grooves of the same spacing as the shaft on the inner periphery of a related cylindrical hole, but in particular, a serration joint is a spline joint whose shaft or hole has teeth or grooves whose tooth surface profile generally has a pressure angle of 60° (ISO 6413).

[0039] By having the second spring S2 penetrate the rotor m1 in this way, the installation area of ​​the housing H and the installation area of ​​the second spring S2 overlap, making the entire device more compact. In addition, the end of the first spring S1 and the end of the second spring S2 are spline-connected to each other, so that the coaxial state is well maintained. Furthermore, the other end of the first spring S1 is supported by the housing H via the external gear g3 of the reducer G and the first spring retainer B1, and the other end of the second spring S2 is supported by the same housing H via the second spring retainer B2 on the opposite side of the motor M.

[0040] These configurations make it possible to obtain a compact active suspension A with a short overall length while ensuring the effective length of the torsion spring S. This configuration allows for a wider range of settings for the spring constant of the torsion spring S, and makes it unnecessary to prepare a separate spring element in order to obtain a desired spring constant for the entire suspension, making it possible to obtain an active suspension A with a rational configuration with a small number of parts.

[0041] Also, with this configuration, the integrated first spring S1 and second spring S2 are stably fixed to the housing H. This makes it difficult for the two to interfere with each other during torsional motion, ensuring that the desired spring characteristics are achieved. Furthermore, the operating resistance of the first spring S1 and second spring S2 is reduced, resulting in a suspension with a high quality operating feel.

[0042] The first spring S1 and the second spring S2 are assembled as follows. First, the reducer G is attached to the housing H to which the motor M is attached. At this time, the first spring S1 is attached in advance to the external gear g3 of the reducer G. Next, the second spring S2 is inserted onto the rotor shaft m2 from the opposite side of the reducer G.

[0043] The end of the first spring S1 is formed with a bottom S1b having a hole S1a, and the end face of the second spring S2 is formed with a female thread S2a. A fastening member J, such as a bolt, is inserted into the bottom S1b from the outside of the hole S1a and screwed into the female thread S2a. The head of the fastening member J abuts against the edge of the hole S1a, and the second spring S2 approaches the bottom S1b as the fastening member J rotates. As a result, the end of the second spring S2 engages with the end of the first spring S1 over a predetermined length, and the other end of the second spring S2 is properly supported by the second spring bearing B2, completing the assembly.

[0044] However, if the other end of the second spring S2 is not in an optimal position relative to the second spring bearing B2, the amount of fastening of the fastening member J may be adjusted to set the position of the second spring S2.

[0045] With this configuration, if there is an error in the installation position of the second spring support B2 relative to the housing H or if the end position of the second spring S2 needs to be accurately positioned relative to the object on which it acts, the installation position of the second spring S2 can be optimized.

[0046] Other embodiments The folded structure of the torsion spring S is not necessarily limited to a two-stage structure, but may also be configured with three or more stages.

[0047] Further, the first spring S1 and the second spring S2 may be joined together by a structure using a fitting key, welding or the like, other than by spline connection.

[0048] As the first spring retainer B1 and the second spring retainer B2, in addition to using bearings that use bearings, bearings that use sliding members may also be used. [Industrial Applicability]

[0049] The active suspension of the present invention can be widely used as a device for controlling the movement of an object by operating a torsion spring through the rotational drive of a motor. [Explanation of symbols]

[0050] A. Active suspension g1 Output section H Housing J Fastening member Medium motor m1 rotor m2 Rotor shaft S1 First torsion spring S1a hole S1b bottom S2 Second torsion spring S2a Female thread X-axis center

Claims

1. a motor including a rotor having a hollow rotor shaft; a housing that houses the motor; an output section that is provided coaxially with an axis of the rotor and rotates in response to the rotation of the rotor; a cylindrical first torsion spring to which rotation from the output portion is transmitted; a second torsion spring, one end of which is fixed to an end of the first torsion spring so as not to rotate relatively around the axis when inserted into the rotor shaft and the first torsion spring, and the other end of which extends towards an acting object; Equipped with active suspension.

2. 2. The active suspension of claim 1, wherein said housing includes at least one bearing for supporting said second torsion spring.

3. The first torsion spring and the second torsion spring are fixed to each other by a spline connection, the first torsion spring and the output portion are connected to one side of the motor; 3. An active suspension as claimed in claim 2, wherein said bearing for said second torsion spring is provided on the other side of said motor.

4. 4. An active suspension as described in claim 3, wherein, at the portion related to the spline connection, a bottom portion having a hole is formed at the end of the first torsion spring, and a female thread portion is formed on the end face of the second torsion spring, and the relative position of the first torsion spring and the second torsion spring can be adjusted depending on the amount of tightening of a male screw member inserted into the bottom portion from outside the hole.

Images