JP5421846B2 - Suspension device - Google Patents

Description

  The present invention relates to an improvement of a suspension device.

  The suspension device that uses the torque output from the motor as a damping force includes, for example, a linear motion type actuator that generates thrust by driving the motor and a hydraulic damper that is connected in series to the actuator. There is something.

  This suspension device includes a pair of coil springs for positioning the rod position connected to the piston to the neutral position relative to the cylinder of the hydraulic damper, and absorbs high-frequency vibrations by the hydraulic damper and these coil springs. However, the transmission of high-frequency vibrations to the actuator side is insulated (see, for example, Patent Document 1).

  More specifically, in the suspension device, a cylindrical member is fixed to the outer periphery of the cylinder, a pair of coil springs are interposed in the cylindrical member in a compressed state, and the upper and lower ends of the series coil springs are connected to the cylinder. The intermediate spring support fixed to the rod is clamped between the coil springs.

  Therefore, in the above-described suspension device, the hydraulic damper is restored to the neutral position, so that the vibration is input to the end of the cylinder where the piston in the hydraulic damper is biased toward the expansion side or the contraction side and there is no room for stroke. The base valve and the rod guide that pivotally supports the rod are prevented from colliding with each other, and the ride comfort in the vehicle is not impaired. That is, the stroke margin of the hydraulic damper can be ensured by providing the coil spring.

JP 2007-290639 A

  By the way, in the suspension device described above, a coil spring is provided to position the rod position in a neutral position with respect to the cylinder. In the state of being in a neutral position, both are interposed between the spring receivers in a state where the free length is reduced by the same length.

  Further, in the conventional suspension device, it is necessary to prevent each coil spring from being separated from the flange provided on the rod in any case, and the other coil spring is compressed by the amount of compression of one coil spring. It must be stretched.

  In such a suspension device, when the stroke length at which the rod strokes from the neutral position is set to be different between the extension side and the contraction side of the hydraulic damper, one of the stroke lengths on the extension side and the contraction side is the other. When the rod strokes from the neutral position to the longer stroke length, one coil spring extends with the longer stroke length, and the other coil spring has the longer stroke length. Both coil springs must be set so that the long stroke length can be stroked on both sides of the expansion and contraction from the state where the rod is in the neutral position. Therefore, if the stroke length is set to be different between the extension side and the contraction side, the set length of these coil springs (the total length of the two coil springs when they are arranged in series and attached to the hydraulic damper) becomes long.

  In addition, the suspension device includes an actuator in addition to the hydraulic damper, and it is necessary to avoid interference with members such as a ball screw nut provided on the actuator. Since the above interference cannot be avoided, a large-diameter coil spring must be used, and if the coil spring set length is increased, the cylinder length of the hydraulic damper must be ensured. Will lead to an increase in length.

  Therefore, in the conventional suspension device, the length of the cylinder and the diameter of the coil spring are increased, and the weight and cost are increased, and the outer diameter is increased to consume a lot of mounting space in the vehicle. There was a problem that.

  Accordingly, the present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a suspension device that is lightweight and space-saving and that can reduce costs.

  In order to achieve the above-described object, the problem-solving means of the present invention is a fluid pressure damper having a direct acting actuator and a rod and a damper main body through which the rod enters and exits, and one of the rod and the damper main body is connected to the actuator. An actuator-side spring receiver and a damper-side spring receiver that are immovable in the axial direction with respect to the other of the damper main body and the rod, and an intermediate that is immovable in the axial direction with respect to one of the damper main body and the rod A spring receiver, an actuator-side spring interposed between the actuator spring receiver and the intermediate spring receiver in a compressed state, and a compression spring interposed between the intermediate spring receiver and the damper-side spring receiver. A suspension-side spring, and the actuator-side spring and the damper-side spring are used to position the rod in the axial direction relative to the damper body at a predetermined position. In down device, characterized in that the spring constant and the spring constant of the damper-side spring of the actuator side spring are different.

  According to the suspension device of the present invention, by setting the spring constant of the actuator-side spring and the spring constant of the damper-side spring differently, compared to the actuator-side spring and the damper-side spring having the same spring constant, Generation of waste in the set length can be suppressed, and the set length of the actuator side spring and the damper side spring can be shortened.

  Then, while providing the actuator side spring receiver and the damper side spring receiver at the same position as the conventional suspension device, the predetermined position of the rod relative to the damper main body is moved from the center of the full stroke of the fluid pressure damper to the damper main body side and the rod side. Can also be set at an eccentric position, and the stroke length on the expansion side and the stroke length on the contraction side of the fluid pressure damper can be made different.

  In the conventional suspension device, at least the actuator side spring and the damper side spring need a set length obtained by adding the contact length to twice the maximum stroke length, and the actuator side spring receiver and the damper side spring receiver Since the predetermined position of the rod is positioned at the middle point, for example, considering that the stroke length of the contraction side of the fluid pressure damper is longer than that of the expansion side, the actuator side spring receiver and the damper side spring receiver inevitably move to the actuator side. However, the actuator side spring support may interfere with the ball spline nut, etc., and the stroke length on the contraction side cannot be set freely unless the spring support is set to a large diameter. Such a problem does not occur in the suspension device of the embodiment.

  In other words, there is no need to change the installation positions of the actuator-side spring receiver and the damper-side spring receiver, so that the stroke length for both expansion and contraction can be freely set while the actuator-side spring receiver is provided at a position that does not interfere with the actuator members. It can be done.

  Accordingly, the cylinder length of the fluid pressure damper is not increased, the outer diameter of the suspension device is not increased, and the stroke length on the expansion side and the contraction side of the fluid pressure damper is saved while saving space. Can be made different.

  In addition, the actuator-side spring and the damper-side spring can be set shorter than the actuator-side spring and the damper-side spring having the same spring constant. This also contributes to avoiding interference between the actuator-side spring receiver and the member of the actuator, avoiding an increase in the outer diameter of the suspension device, and isting waste in the actuator-side spring and the damper-side spring. Since the length can be reduced, the weight can be reduced accordingly.

It is a longitudinal cross-sectional view of the suspension apparatus in one embodiment. It is a figure explaining in principle about the setting of the actuator side spring and damper side spring of the suspension apparatus in one embodiment.

  The present invention will be described below based on the embodiments shown in the drawings. As shown in FIG. 1, a suspension device S according to an embodiment includes a direct-acting actuator A, a rod 3 and a damper body 4 through which the rod 3 enters and exits, and a fluid in which the rod 3 is connected to the actuator A. A pressure damper D, an actuator-side spring receiver 5 and a damper-side spring receiver 6 that are fixed in the axial direction with respect to the damper main body 4, and an intermediate spring receiver 7 that is fixed in the axial direction with respect to the rod 3. An actuator-side spring 8 interposed between the actuator spring receiver 5 and the intermediate spring receiver 7 in a compressed state, and a compressor-side spring interposed between the intermediate spring receiver 7 and the damper-side spring receiver 6. The damper side spring 9 is provided.

  In the case of the suspension device S, an eye bracket 11 provided at the lower end in FIG. 1 of the fluid pressure damper D can be attached to a sprung member of a vehicle (not shown) via a mount 10 provided on the outer periphery of the actuator A. It attaches to the unsprung member of the vehicle which is not shown in figure, and can be interposed between the sprung member and unsprung member of the vehicle.

  Further, in the suspension device S, a cylindrical air piston 12 attached to the outer periphery of the damper main body 4, a cylindrical air chamber 13 attached to the outer periphery of the actuator A, the air piston 12 and the air The air spring AS is connected to the actuator by forming an air chamber G in which the outer periphery of the actuator A and the fluid pressure damper D is filled with a gas, which includes a cylindrical diaphragm 14 mounted in a folded state with the chamber 13. A and the fluid pressure damper D are provided on the outer periphery. The air spring AS functions as a suspension spring that exerts an elastic force against the relative movement of the damper body 4 and the actuator A in the vertical direction in FIG. In addition, you may make it interpose between the damper main body 4 and the actuator A by using a coil spring as a suspension spring instead of the air spring AS.

  In this embodiment, the actuator A includes a motion conversion mechanism T that converts linear motion of a screw shaft 1 as a linear motion member into rotational motion of a ball screw nut 2 as a rotation member, and a ball screw nut in the motion conversion mechanism T. And a motor M that is coupled to 2 and is a linear-acting actuator that linearly moves the screw shaft 1 in the axial direction that is the vertical direction in FIG. 1 by rotationally driving the ball screw nut 2. The output shaft is the screw shaft 1.

  Specifically, the motor M is housed and fixed in a case 15 that rotatably holds the ball screw nut 2, and the rotor is connected to the ball screw nut 2. The case 15 holds a ball spline nut 16 in addition to the ball screw nut 2 therein. On the other hand, the screw shaft 1 is screwed into the ball screw nut 2 while being inserted into the inner periphery of the ball spline nut 16 and stopped. Further, although not shown, the rotor of the motor M has a hollow structure and the screw shaft 1 is allowed to pass therethrough, and the screw shaft 1 can linearly move in the axial direction which is the vertical direction in FIG. It is possible. The case 15 may be integrated with a frame that is a casing of the motor M. Further, the rotation prevention of the screw shaft 1 can employ a method other than the ball spline.

  As can be understood from the above description, in this actuator A, the screw shaft 1 can be linearly moved in the axial direction by driving the motor M and rotating the ball screw nut 2. By forcibly moving the screw shaft 1 linearly, the ball screw nut 2 can be rotated and the motor M can be forcibly rotated.

  In the above description, when the motor M is driven, the ball screw nut 2 rotates, and the screw shaft 1 screwed into the ball screw nut 2 exhibits a linear motion in the vertical direction in FIG. Alternatively, the screw shaft 1 may be connected to the motor M to serve as a rotating member, and the ball screw nut 2 may be driven so as to exhibit a linear motion in the vertical direction. In that case, the ball screw nut 2 is connected to the fluid pressure damper D.

  A cylindrical air chamber 13 having a top is provided on the outer periphery of the case 15, and an annular rebound stopper 17 that restricts the full extension is provided on the inner periphery of the air chamber 13.

  In this embodiment, the motion conversion mechanism T is constituted by the screw shaft 1 and the ball screw nut 2. However, the rotation of the rotor of the motor M is transmitted to the rotating member, and the linear motion member moves linearly. Therefore, in addition to the combination of the screw shaft 1 and the ball screw nut 2, the rotation member may be a pinion gear or a worm gear, and the linear motion member may be a rack. Furthermore, the actuator A is composed of the motor M and the motion conversion mechanism T, and may be a linear motor. However, since the gear ratio can be set by the motion conversion mechanism T, it can contribute to the miniaturization of the motor M. There is an advantage that the degree of freedom of the thrust setting range of the actuator is increased.

  The fluid pressure damper D exhibits a predetermined damping force when the rod 3 is expanded and contracted with respect to the damper body 4 and is provided mainly for the purpose of absorbing high-frequency vibrations.

  Specifically, the fluid pressure damper D is configured as a double cylinder type damper, and includes two cylinders 18 and two pressure chambers R1 and R2 defined by a piston 19 slidably inserted into the cylinder 18. A damper main body 4 including an outer cylinder 20 that covers the outer periphery of the cylinder 18, a reservoir R formed by an annular gap between the cylinder 18 and the outer cylinder 20, and a partition member 23 that partitions the pressure chamber R 2 and the reservoir R And a rod 3 connected to the piston 19 and movably inserted into the cylinder 18. The pressure chambers R1 and R2 are filled with a fluid, and the fluid may be a gas other than a liquid such as hydraulic oil, water, or an aqueous solution. In the case of this embodiment, the volume of the fluid in the cylinder 18 due to the temperature change is set by supplying the liquid from the reservoir R to the cylinder 18 or discharging the liquid from the cylinder 18 to the reservoir R. Although the change and the volume of the rod 3 entering and exiting the cylinder 18 are compensated, the reservoir R can be eliminated when the fluid is gas.

  The piston 19 is provided with passages 19a and 19b communicating with the pressure chamber R1 and the pressure chamber R2, and damping valves 21 and 22 provided in the passages 19a and 19b, respectively. The damping valve 21 sets the passage 19a as a one-way passage that allows only the flow of liquid from the upper pressure chamber R1 to the lower pressure chamber R2 in FIG. 1, and the flow of liquid passing through the passage 19a. To give resistance. On the contrary, the damping valve 22 sets the passage 19b as a one-way passage that allows only the flow of liquid from the pressure chamber R2 to the pressure chamber R1, and provides resistance to the flow of liquid passing through the passage 19b. It has become.

  Further, the partition member 23 is provided with passages 23a and 23b communicating the pressure chamber R2 and the reservoir R, a damping valve 24 provided in the passage 23a, and a check valve 25 provided in the passage 23b. The damping valve 24 sets the passage 23a as a one-way passage that allows only the flow of liquid from the pressure chamber R2 to the reservoir R, and provides resistance to the flow of liquid passing through the passage 23a. On the other hand, the check valve 25 sets the passage 23b as a one-way passage that allows only the flow of liquid from the reservoir R to the pressure chamber R2, and gives little resistance to the flow of liquid passing through the passage 23b. It is like that.

  The fluid pressure damper D configured as described above is a liquid heading from the pressure chamber R1 compressed by the piston 19 to the expanding pressure chamber R2 when the rod 3 moves in the upward direction in FIG. The damping valve 21 applies resistance to the flow of the gas, generates differential pressure in the pressure chamber R1 and the pressure chamber R2, and applies the differential pressure to the piston 19 to suppress the movement of the rod 3 relative to the damper main body 4. Generate power. Note that the volume of liquid with which the rod 3 retreats from the cylinder 18 is insufficient in the cylinder 18, but the check valve 25 opens the passage 23 b and the insufficient liquid is supplied from the reservoir R into the cylinder 18. The On the other hand, in the fluid pressure damper D, when the rod 3 moves in the downward direction in FIG. 1 with respect to the damper main body 4, the liquid flow toward the pressure chamber R1 expanding from the pressure chamber R2 compressed by the piston 19 and the reservoir The damping valve 22, 24 gives resistance to the liquid flow toward R, creates a differential pressure in the pressure chamber R 2 and the pressure chamber R 1, and moves the rod 3 relative to the damper body 4 by applying the differential pressure to the piston 19. The compression side damping force which suppresses is generated. In this case, the fluid pressure damper D includes the reservoir R, and the damping valve 24 can exert the compression side damping force. Therefore, the fluid pressure damper D moves the damping valve 22 from the pressure chamber R2 to the pressure chamber R1. A check valve that allows only flow may be used. Further, the structure of the fluid pressure damper D is an example and is configured as the above-described multi-cylinder damper. For example, the damper main body 4 may be a single cylinder damper having only a cylinder without an outer cylinder. Good.

  As described above, the suspension device S of the present embodiment includes the motor M having a large moment of inertia, and has a characteristic that it is difficult to expand and contract with respect to an input of high-frequency vibration and easily transmits vibration. The fluid pressure damper D is connected in series to the motion conversion mechanism T, and vibration energy is absorbed by the fluid pressure damper D and vibrated toward the actuator A side with respect to the input of high frequency vibration such as vibration with relatively high acceleration. Can be prevented from being transmitted. Although the rod 3 of the fluid pressure damper D is connected to the actuator A at the illustrated position, the damper main body 4 may be connected to the actuator A.

  An air piston 12 that covers the outer periphery of the damper main body 4 is provided on the outer periphery of the damper main body 4 of the fluid pressure damper D. The air piston 12 includes an annular base portion 12a attached to the outer periphery of the damper main body 4 and a cylindrical portion 12b rising from the outer periphery of the base portion 12a. An actuator-side spring receiver 5 is provided on the inner periphery of the cylindrical portion 12b. Is installed. The outer diameter of the cylindrical portion 12b is smaller than the inner diameter of the air chamber 13, and can enter and exit the air chamber 13 without interfering with the air chamber 13.

  The actuator-side spring receiver 5 is suspended from an annular seat 5a, a cylindrical fitting portion 5b that rises from the outer periphery of the seat 5a and fits to the inner periphery of the cylindrical portion 12b of the air piston 12, and the inner periphery of the seat 5a. And a cylindrical inner cylinder 5c.

  The upper end 5d of the fitting portion 5b of the actuator-side spring receiver 5 is bent toward the inner circumference, and the upper end 5d of the fitting portion 5b is added to the cylinder portion 12b of the air piston 12 from the outer circumference over the entire circumference. By engaging with the lower end of the annular concave caulking portion 12c formed by tightening, the upward movement of the actuator-side spring receiver 5 is restricted with respect to the air piston 12, and the caulking portion 12c causes the actuator side to move upward. The spring receiver 5 is positioned with respect to the air piston 12. Moreover, the attachment method of the actuator side spring receiver 5 to the air piston 12 is an example, and various attachment methods such as welding, press-fitting, and screwing can be employed in addition to those described above.

  In the present embodiment, the actuator-side spring receiver 5 is attached to the inner periphery of the air piston 12, but in addition to the air piston 12, the damper body 4 is separately attached to the actuator side. A cylinder or the like that can immovably provide the spring receiver 5 in the axial direction may be provided, but by integrating the function of attaching the actuator-side spring receiver 5 to the damper body 4 on the air piston 12, the number of parts can be reduced. Unnecessary enlargement of the suspension device S can be avoided. When the air spring AS is not provided in the suspension device S, a member such as a cylinder is provided on the outer periphery of the damper main body 4 so that the actuator-side spring receiver 5 does not move in the axial direction on the damper main body 4 via the member. You may make it attach to.

  Further, the inner cylinder 5c provided on the actuator-side spring receiver 5 has a function of fitting to the inner periphery of the upper end of the actuator-side spring 8 to be described later and aligning the actuator-side spring 8. If it is not necessary to align the spring 8, it can be eliminated.

  Further, a damper side spring receiver 6 is mounted on the outer periphery of the damper body 4, and the damper side spring receiver 6 is fixed to the damper body 4 in the axial direction. The damper side spring receiver 6 and the actuator side Between the spring receiver 5, an actuator side spring 8 and a damper side spring 9 are interposed in series in a compressed state. The damper side spring receiver 6 is mounted on the outer periphery of the damper main body 4, but in this embodiment, since the air piston 12 is provided, the base portion 12a of the air piston 12 functions as a damper side spring receiver. A damper-side spring support may be provided on the inner periphery of the air piston 12.

  If the actuator-side spring 8 and the damper-side spring 9 are interposed in a compressed state between the actuator-side spring receiver 5 and the damper-side spring receiver 6 in this way, the actuator-side spring receiver 5 is always in FIG. Although it is in a state of being biased upward, as described above, since the upward movement is restricted by the crimping portion 12c, it does not move in the axial direction which is the vertical direction in FIG. Is done. The shape of the actuator-side spring receiver 5 is an example and is not limited to this, but the actuator-side spring receiver 5 is directed from the outer periphery of the seat 5a that supports the upper end of the actuator-side spring 8 toward the opposite spring side. The fitting portion 5b that rises up and is positioned by the crimping portion 12c so that the crimping portion 12c is provided in a range that does not face the actuator-side spring 8 in the radial direction. be able to. In this way, the actuator-side spring 8 and the crimping portion 12c formed by reducing the diameter of the cylindrical portion 12b of the air piston 12 do not oppose each other in the radial direction, so that the crimping portion 12c and the actuator-side spring 8 interfere with each other. Therefore, the air piston 12 can be made smaller in diameter.

  The actuator side spring 8 and the damper side spring 9 are both interposed between the actuator side spring receiver 5 and the damper side spring receiver 6 in a compressed state. In between, an intermediate spring receiver 7 is interposed which is fixed to the upper end of the rod 3 of the fluid pressure damper D.

  The intermediate spring receiver 7 includes an annular seat portion 7a sandwiched between the actuator-side spring 8 and the damper-side spring 9, an annular attachment portion 7b attached to the upper end of the rod 3, and an inner periphery of the seat portion 7a. The cylindrical part 7c connected to the outer periphery of the part 7b is comprised.

  By being sandwiched between the actuator-side spring 8 and the damper-side spring 9 in this way, the intermediate spring receiver 7 is positioned at a position where the urging forces generated by the actuator-side spring 8 and the damper-side spring 9 are balanced. . The actuator-side spring receiver 5 and the damper-side spring receiver 6 in which the actuator-side spring 8 and the damper-side spring 9 are interposed are fixed to the damper body 4 in the axial direction, and the intermediate spring receiver 7 is connected to the rod 3 in the axial direction. Since it is immovable, the axial position of the rod 3 with respect to the damper main body 4 is positioned at a predetermined position by the actuator-side spring 8 and the damper-side spring 9. The suspension device S includes an air spring AS as a suspension spring. The actuator-side spring 8 and the damper-side spring 9 can be used even if the suspension device S is interposed between the vehicle body and the axle of the vehicle. Although the weight is not supported, the weight of the member on the linear motion side in the actuator A is supported.

  The suspension device S configured as described above can rotate the ball screw nut 2 with the torque generated by the motor M to linearly move the screw shaft 1 in the vertical direction in FIG. The linear motion of the screw shaft 1 can also be suppressed by applying a thrust to the screw shaft 1 by positively generating torque in the motor M in response to the input. When the screw shaft 1 is forcibly linearly moved by an external force, the rotor of the motor M connected to the ball screw nut 2 exhibits a rotational motion, and the motor M suppresses the rotational motion of the rotor due to the induced electromotive force. It functions to generate torque and suppress linear movement of the screw shaft 1.

  Therefore, the suspension device S not only generates a damping force that suppresses the linear motion of the screw shaft 1 but also functions as an actuator. Therefore, the suspension device S is connected to the vehicle body and the axle of the vehicle. If used in between, the attitude control of the vehicle body can be performed simultaneously, thereby functioning as an active suspension.

  The actuator-side spring 8 and the damper-side spring 9 expand and contract when high-frequency vibration is input from the axle side to the suspension device S to insulate transmission of the high-frequency vibration to the vehicle body side. The high-frequency vibration is quickly damped by the damping force generated by the fluid pressure damper D arranged in parallel with the spring 9. As described above, the fluid pressure damper D, the actuator side spring 8 and the damper side spring 9 cooperate to insulate transmission of high-frequency vibration to the vehicle body side and quickly absorb vibration.

  Further, since the actuator-side spring 8 and the damper-side spring 9 function to return the axial relative position between the damper body 4 and the rod 3 to a predetermined position, the fluid pressure damper D remains in the most expanded or contracted state. Thus, it is possible to avoid a situation in which the piston interferes with the upper end or lower end of the damper body 4 and cannot absorb high-frequency vibrations or deteriorates the riding comfort in the vehicle, and the suspension device can ensure the stroke margin of the fluid pressure damper D. The reliability of S can be improved.

  In this case, the predetermined position refers to the damper main body 4 by the balance of the urging forces of the actuator side spring 8 and the damper side spring 9 with the weight of the member on the linear motion side of the actuator A and the weight of the rod 3 supported. This is the axial position where the rod 3 is statically positioned, and is a position arbitrarily determined by the setting of the suspension device S.

  In the case of this embodiment, in particular, when the axial position of the rod 3 with respect to the damper body 4 is positioned at a predetermined position, the rod 3 becomes the extension side of the fluid pressure damper D with respect to the damper body 4. 1 is set so that the stroke length when making the maximum stroke upward in the middle of 1 and the stroke length when making the maximum stroke downward in FIG. 1, which is the contraction side of the fluid pressure damper D, are different. Is set so that the stroke length toward the contraction side is longer than the stroke length toward the extension side from the predetermined position of the rod 3.

  That is, in the case of this embodiment, as shown in the drawing, the rod 3 is moved by the actuator side spring 8 and the damper side spring 9 so that the position of the piston 19 is positioned above the center of the cylinder 18. The damper body 4 is relatively positioned in the axial direction, and this positional relationship is set as a predetermined position.

  In this embodiment, when the rod 3 is positioned with respect to the damper main body 4 so that the position of the piston 19 is positioned above the center of the cylinder 18 in this way, in the present embodiment, the actuator-side spring 8 If the spring constant of the damper-side spring 9 is set larger than the spring constant, and the actuator-side spring 8 and the damper-side spring 9 are interposed between the actuator-side spring receiver 5 and the damper-side spring receiver 6 in a compressed state, the actuator Since the side spring 8 is contracted more than the damper side spring 9, even if the actuator side spring receiver 5 and the damper side spring receiver 6 are installed at the same position as the conventional suspension apparatus, the intermediate spring receiver 7 is used as the conventional suspension apparatus. Compared to the above, the stroke length to the contraction side is longer than the stroke length from the predetermined position of the rod 3 to the extension side compared to So that the can be set to.

  When the spring constant of the actuator-side spring 8 is k1 and the spring constant of the damper-side spring 9 is k2, the actuator-side spring 8 and the damper-side spring 9 are placed between the actuator-side spring receiver 5 and the damper-side spring receiver 6. In a state where the rod 3 is interposed in a compressed state and positioned at a predetermined position, the initial contraction length of the actuator-side spring 8: initial contraction length of the damper-side spring 9 = k2: k1. In addition, since k1 <k2 is set, it can be seen that the initial contraction length of the actuator-side spring 8 is longer than the initial contraction length of the damper-side spring 9.

  Subsequently, when the rod 3 moves from the predetermined position to the fluid pressure damper D toward the expansion side, the actuator-side spring 8 contracts by the stroke and the damper-side spring 9 expands by the stroke. The spring 8 and the damper-side spring 9 exert an urging force of xx (k1 + k2) that suppresses the stroke with respect to the stroke amount x. When the rod 3 makes the maximum stroke from the predetermined position to the expansion side of the fluid pressure damper D, the actuator-side spring 8 is compressed most and the damper-side spring 9 is expanded most.

  On the other hand, when the rod 3 moves from the predetermined position to the fluid pressure damper D toward the contraction side, the actuator-side spring 8 expands by the stroke and the damper-side spring 9 contracts by the stroke. The actuator-side spring 8 and the damper-side spring 9 exert a biasing force of xx (k1 + k2) that suppresses the stroke with respect to the stroke amount x. When the rod 3 makes the maximum stroke from the predetermined position to the contraction side of the fluid pressure damper D, the actuator-side spring 8 is expanded the most, and the damper-side spring 9 is compressed most.

  Here, as described above, since the actuator-side spring 8 and the damper-side spring 9 have different spring constants, the actuator-side spring receiver 5 and the damper-side spring receiver 6 are inserted in a compressed state between them. Since the contraction is performed according to the above ratio from the free length, the initial contraction lengths are different from each other.

  As shown in FIG. 2, the actuator-side spring 8 has a maximum stroke length L1 when the rod 3 is stroked from the state in which it is contracted by the initial contraction length, that is, from the state in which the rod 3 is in a predetermined position to the extension side of the fluid pressure damper D. It is only necessary to be able to contract as described above, and to extend more than the maximum stroke length L2 when the stroke is made from the contracted state by the initial contraction length to the contraction side of the fluid pressure damper D. On the other hand, the damper side spring 9 can be extended by the initial contraction length, that is, the maximum stroke length L1 to the extension side when the fluid pressure damper D strokes from the state in which the rod 3 is in a predetermined position. It suffices if the stroke can be shortened by the maximum stroke length L2 or more when the stroke is made from the initial contraction length to the contraction side of the fluid pressure damper D.

Then, the initial contraction length of the actuator-side spring 8 is set to be not less than the maximum stroke length L2 when the rod 3 is moved from the predetermined position to the contraction side of the fluid pressure damper D, and the initial contraction length is contracted. The maximum stroke length L1 when the rod 3 is in a predetermined position and stroked from the state H1 to the extension side of the fluid pressure damper D is obtained by subtracting the contact length e1 which is the length of the most compressed state. If the setting is made as described above, the actuator-side spring 8 will not be separated from the intermediate spring receiver 7. Similarly, the initial contraction length of the damper-side spring 9 is set to be not less than the maximum stroke length L1 when the rod 3 is stroked from the predetermined position to the expansion side of the fluid pressure damper D, and the initial contraction length is contracted. The maximum stroke length when the rod 3 is stroked from the state where the rod 3 is in a predetermined position to the contraction side of the fluid pressure damper D from the length H2 of the dead state, which is the length of the most compressed state. If set to be equal to or greater than L2, the damper-side spring 9 will not be separated from the intermediate spring receiver 7.
Therefore, the set length, which is the total length of the actuator-side spring 8 and the damper-side spring 9 arranged in series, is expanded or contracted by a length that is greater than the maximum stroke length L2 on the expansion side plus the maximum stroke length L2 on the contraction side. The stroke length may be a length added to the contact lengths e1 and e2.

  Here, as in the conventional suspension device, it is considered to set the actuator-side spring and the damper-side spring to the same spring constant. Also in this case, the actuator-side spring can be contracted from the state contracted by the initial contraction length to the maximum stroke length L1 when the actuator is stroked to the expansion side of the fluid pressure damper D. It suffices if it can extend over the maximum stroke length L2 when it is stroked to the contraction side of the damper D, and even when the damper side spring is against the contraction side of the fluid pressure damper D from the contracted state by the initial contraction length. It is sufficient that the stroke can be extended by the maximum stroke length L1 or more, and the stroke can be reduced by the stroke length L2 or more when the stroke is contracted from the initial contraction length to the contraction side of the fluid pressure damper D. However, when the actuator-side spring and the damper-side spring have the same spring constant, the initial contraction length becomes equal. Therefore, in order to prevent the actuator-side spring and the damper-side spring from being separated from each other, the initial contraction length of the actuator-side spring and the damper-side spring is set to The maximum stroke length L1, L2 is set to the longer stroke length, and the length obtained by subtracting the contact length, which is the length of the most compressed state, from the length of the initial contraction length, The longer stroke length of the maximum stroke lengths L1 and L2 must be set. In short, when the actuator-side spring and the damper-side spring have the same spring constant, a set length obtained by adding a contact length to a length that is at least twice the maximum stroke length is required.

  On the other hand, if the spring constant of the actuator side spring 8 and the spring constant of the damper side spring 9 are set differently, as described above, the spring constant of the actuator side spring 8 and the set length of the damper side spring 9 are set. Needs to be a length obtained by adding the contact lengths e1 and e2 to the length of the total stroke L of the fluid pressure damper D, and requires a set length obtained by adding the contact length to twice the maximum stroke length. Compared to the actuator-side spring and the damper-side spring having the same spring constant, the generation of waste in the set length can be suppressed and the set length can be shortened.

  Then, the actuator side spring receiver 5 and the damper side spring receiver 6 are provided at the same position as the conventional suspension device, and the predetermined position of the rod 3 with respect to the damper main body 4 is moved from the center of the full stroke of the fluid pressure damper D to the damper main body 4. It is possible to set the position eccentric to both the rod side and the rod 3 side, and the stroke length on the expansion side and the stroke length on the contraction side of the fluid pressure damper D can be made different.

  Further, as described above, in the conventional suspension device, the set length of the actuator-side spring and the damper-side spring requires a free length obtained by adding the contact length to twice the maximum stroke length. Since the predetermined position of the rod 3 is positioned at the midpoint of the damper-side spring receiver, for example, considering that the stroke length of the contraction side of the fluid pressure damper D is longer than the extension side, the actuator-side spring receiver inevitably The damper-side spring support will be installed close to the actuator A side, and the actuator-side spring support may interfere with the ball spline nut, etc. If the spring support is not set to a large diameter, the stroke length on the contraction side However, in the suspension device of the present embodiment, such a problem does not occur.

  In other words, since there is no need to change the installation positions of the actuator-side spring receiver 5 and the damper-side spring receiver 6, the stroke length of both expansion and contraction is maintained while the actuator-side spring receiver 5 is provided at a position that does not interfere with the members in the actuator A. Can be set freely. Accordingly, the cylinder length of the fluid pressure damper D is not increased, the outer diameter of the suspension device S is not increased, the space length is saved, and the stroke length and the contraction side of the fluid pressure damper D are reduced. The stroke length can be made different.

  Further, among the stroke lengths of the rod 3 from the predetermined position with respect to the tamper body 4, by setting the contraction side longer than the expansion side of the fluid pressure damper D, while avoiding an increase in the total length of the fluid pressure damper D, A stroke margin can be gained with respect to the thrust input from the road surface, and the so-called occurrence of bottoming of the fluid pressure damper D can be reduced, and the riding comfort in the vehicle can be improved. Further, by setting in this way, the intermediate spring receiver 7 is disposed on the actuator-side spring receiver 5, so that the length of the cylindrical portion 7c is shortened or the position of the seat portion 7a of the intermediate spring receiver 7 is reached. In some cases, the cylindrical portion 7c is abolished, and the seat portion 7a and the mounting portion 7b are integrated so that they can be integrated into a single annular member. In some cases, there is an advantage that the structure of the intermediate spring receiver 7 can be simplified.

  Further, by making the free length of the actuator-side spring 8 and the free length of the damper-side spring 9 different from each other, a particularly large difference is provided between the extension-side stroke length and the contraction-side stroke length of the fluid pressure damper D. When positioning the rod 3 at a predetermined position with respect to 4, not only has the advantage that the design of the actuator-side spring 8 and the damper-side spring 9 is easy, but also the two are installed opposite to each other when installed in the suspension device S. This reduces work mistakes that occur.

  In the above description, the actuator-side spring receiver 5 and the damper-side spring receiver 6 are fixed in the axial direction with respect to the damper body 4, and the intermediate spring receiver 7 is fixed in the axial direction with respect to the rod 3. However, on the contrary, the actuator-side spring receiver 5 and the damper-side spring receiver 6 are immovable in the axial direction with respect to the rod 3, and the intermediate spring receiver 7 is immovable in the axial direction with respect to the damper body 4. As an alternative, the damper body 4 may be connected to the linear motion member of the actuator A. In the above-described embodiment, the contraction-side stroke length of the fluid pressure damper D is set longer than the expansion-side stroke length. Conversely, the spring constant of the damper-side spring 9 is set to the spring of the actuator-side spring 8. By making it smaller than the constant, the stroke length on the extension side can be set longer than the stroke length on the contraction side.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

  The present invention can be used for a suspension device interposed between a vehicle body and an axle of a vehicle.

DESCRIPTION OF SYMBOLS 1 Screw shaft as a linear motion member 2 Ball screw nut as a rotation member 3 Rod 4 Damper main body 5 Actuator side spring receiver 5a Seat 5b Fitting part 5c Inner cylinder 5d Upper end 6 Damper side spring receiver 7 Intermediate spring receiver 7a Seat part 7b Mounting part 7c Cylindrical part 8 Actuator side spring 9 Damper side spring 10 Mount 11 Eye bracket 12 Air piston 12a Base part 12b Cylinder part 12c Clamping part 13 Air chamber 14 Diaphragm 15 Case 16 Ball spline nut 17 Rebound stopper 18 Cylinder 19 Piston 19a, 19b, 23a, 23b Passage 20 Outer cylinder 21, 22, 24 Damping valve 23 Partition member 25 Check valve A Actuator AS Air spring D Fluid pressure damper G Air chamber M Motor R Reservoir R1, R2 Pressure chamber S Suspension device T Motion conversion mechanism

Claims (5)

A fluid pressure damper having a direct-acting actuator, a rod and a damper main body through which the rod enters and exits, and connecting one of the rod and the damper main body to the actuator; and axially with respect to the other of the damper main body and the rod Between the actuator-side spring receiver and the damper-side spring receiver, the intermediate-spring receiver fixed in the axial direction with respect to one of the damper body and the rod, and the actuator-spring receiver and the intermediate-spring receiver. An actuator-side spring interposed in a compressed state, and a damper-side spring interposed in a compressed state between the intermediate spring receiver and the damper-side spring receiver, the actuator-side spring and the damper-side spring, In the suspension device for positioning the axial position of the rod at a predetermined position with respect to the damper body, Suspension and wherein the spring constant of the path-side spring are different. The suspension device according to claim 1, wherein a stroke length of the rod from the predetermined position with respect to the tamper body is different between an extension side and a contraction side of the fluid pressure damper. The suspension device according to claim 1 or 2, wherein the contraction side of the stroke length of the rod from the predetermined position relative to the tamper body is longer than the expansion side of the fluid pressure damper. The suspension according to any one of claims 1 to 3, wherein the free lengths of the actuator-side spring and the damper-side spring are both set to a length obtained by adding the total stroke length of the fluid pressure damper to the contact length. apparatus. 6. The suspension device according to claim 1, wherein the free length of the actuator side spring and the free length of the damper side spring are different.

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