JP2015135148A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension device which includes an elastic body for developing reactive force to counterbalance the reactive force of an air spring when elongated to a maximum, and whose spring characteristics are gently changed since the elastic body is fully elongated, resulting in the ride quality improvement of a vehicle.SOLUTION: A suspension device F includes a telescopic type tube member 1 consisting of a vehicle body side tube 10 and a wheel side tube 11, the air spring using gas filled in the tube member 1 while being compressed, for developing reactive force according to the compression amount of the tube member 1, and an elastic body 2 for developing reactive force to counterbalance the reactive force of the air spring when elongated to a maximum. The spring constant of the elastic body 2 is changed on the way.

Description

  The present invention relates to a suspension device.

  Some suspension devices interposed between a vehicle body and wheels in a vehicle use an air spring as a suspension spring that elastically supports the vehicle body and absorbs an impact caused by road surface unevenness.

  For example, the suspension device disclosed in Patent Document 1 is a front fork that suspends a front wheel in a straddle-type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle, and includes a telescopic tube member including a vehicle body side tube and a wheel side tube. Gas is compressed in the tube member while being compressed to function as a suspension spring composed of an air spring.

  In the above suspension device, the spring characteristics of the air spring are as shown by a solid line a and a broken line a in FIG. 4, and the air spring exerts a reaction force even when the suspension device is fully extended, and extends the suspension device. It is to be urged in the direction. For this reason, when the air spring is used as it is as a suspension spring, the spring characteristics are greatly different from those when a suspension spring composed of a coil spring is used.

  Therefore, the suspension device disclosed in Patent Document 1 includes an elastic body that exhibits a reaction force that cancels the reaction force caused by the air spring at the time of maximum extension, and is a combination of the spring characteristic a of the air spring and the spring characteristic d of the elastic body. The characteristics (combination of solid lines a and d in FIG. 4B) are brought close to the spring characteristics of a suspension spring made of a coil spring.

JP 2010-185571 A

  However, in the suspension device described above, the elastic body is composed of a single coil spring called a balance spring, and the spring constant does not change, so the stroke range E4 until the elastic body is fully extended and the stroke range after the elastic body is fully extended. At E5, the change in the spring characteristics of the suspension device is large, and the passenger may feel uncomfortable.

  Therefore, an object of the present invention is to provide a suspension device having an elastic body that exhibits a reaction force that counteracts the reaction force of the air spring at the time of maximum extension. It is to loosen and improve the ride comfort of the vehicle.

  Means for solving the above-mentioned problems include a telescopic tube member composed of a vehicle body side tube and a wheel side tube, and a gas corresponding to the amount of compression of the tube member sealed by compressing gas in the tube member. An air spring that exerts a force and an elastic body that exerts a reaction force that counteracts the reaction force of the air spring at the time of maximum extension are provided, and the spring constant of the elastic body changes midway.

  According to the present invention, in a suspension device including an elastic body that exhibits a reaction force that cancels the reaction force caused by the air spring at the maximum extension, the change in the spring characteristics of the suspension device at the boundary of the extension of the elastic body is moderated. This makes it possible to improve the riding comfort of the vehicle.

It is the front view which notched and showed the principal part of the suspension apparatus which concerns on one embodiment of this invention. It is the front view which expanded and showed the elastic body of the suspension apparatus which concerns on one embodiment of this invention. (A) is the figure which showed the spring characteristic of each of the air spring, elastic body, and extending spring of the suspension apparatus which concerns on one embodiment of this invention. (B) is the figure which showed the synthetic | combination characteristic of the spring characteristic of the air spring of (a), the spring characteristic of an elastic body, and the spring characteristic of an air spring and an elastic body. (C) shows the combined characteristics of the spring characteristics of the air spring of (a), the spring characteristics of the elastic body, the spring characteristics of the extension spring, and the spring characteristics of the air spring, the elastic body and the extension spring. FIG. (A) is the figure which showed the spring characteristic of the air spring of the conventional suspension apparatus, and each elastic body. (B) is the figure which showed the synthetic | combination characteristic of the spring characteristic of the air spring of (a), the spring characteristic of an elastic body, and the spring characteristic of an air spring and an elastic body.

  A suspension device according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  As shown in FIG. 1, the suspension device F according to the present embodiment includes a telescopic tube member 1 including a vehicle body side tube 10 and a wheel side tube 11, and encloses the tube member 1 while compressing gas. An air spring that exhibits a reaction force according to the compression amount of the tube member 1 and an elastic body 2 that exhibits a reaction force that cancels the reaction force of the air spring at the time of maximum extension are provided. The spring constant of the body 2 changes midway.

  In the present embodiment, the suspension device F is a front fork that suspends a front wheel of a saddle-ride type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle, and a pair of leg portions f1 that support the front wheel from both sides (only one leg portion f1 is illustrated). The other leg portion is omitted), a vehicle body side bracket (not shown) connected to the vehicle body frame that is the frame of the vehicle body, and the leg portions f1 and the front wheel axles. And a wheel side bracket 12 for connecting the two. In the present embodiment, the present invention is embodied in both of the paired legs f1, but may be embodied only in one leg f1.

  Since the paired legs f1 have a common configuration, only one leg f1 will be described in detail below. The leg portion f1 includes a telescopic tube member 1 that is an outer shell of the leg portion f1, and a shock absorber body D that is accommodated in the tube member 1. The tube member 1, the shock absorber body D, A reservoir R for storing hydraulic oil is formed between them. In the present embodiment, since the hydraulic oil is used as the fluid for generating the damping force, the hydraulic oil is stored in the reservoir R, but other liquid may be used.

  An air chamber G is formed on the upper side through the fluid level (not shown) of the hydraulic oil, while the gas is compressed and sealed. The compressed gas in the air chamber G functions as an air spring that exerts a reaction force corresponding to the amount of compression of the tube member 1, and this air spring constantly urges the tube member 1 in the extending direction to It functions as a suspension spring that is elastically supported. Since the compression amount of the tube member 1 is equal to the compression amount of the suspension device F, it can be said that the air spring exerts a reaction force corresponding to the compression amount of the suspension device F and urges the suspension device F in the extending direction. . In the present embodiment, the air chamber G is formed from the reservoir R to the buffer body D, and the air chamber in the reservoir R is hereinafter referred to as a reservoir internal air chamber g1.

  The tube member 1 is a telescopic type including a vehicle body side tube 10 connected to a vehicle body side bracket (not shown) and a wheel side tube 11 connected to the wheel side bracket 12 to enter and exit the vehicle body side tube 10. When an impact due to road surface unevenness is input to the wheel, the wheel side tube 11 enters and exits the vehicle body side tube 10 to expand and contract. In the present embodiment, the suspension device F is an inverted front fork in which the wheel side tube 11 enters and exits the vehicle body side tube 10, but an upright front fork in which the vehicle body side tube 10 enters and exits the wheel side tube 11. It may be.

  The upper end opening of the tube member 1 is closed by the cap member 13, and the lower end opening of the tube member 1 is closed by the wheel side bracket 12, and the overlapping portion of the vehicle body side tube 10 and the wheel side tube 11 is covered. The lower end opening of the cylindrical gap formed therebetween is closed by an annular oil seal 14 and a dust seal 15 that are held on the lower inner periphery of the vehicle body side tube 10 and are in sliding contact with the outer peripheral surface of the wheel side tube 11. Therefore, the hydraulic oil and gas accommodated in the tube member 1 are prevented from leaking out of the tube member 1.

  The cap member 13 is provided with an air valve 16, and gas can be supplied to and discharged from the air chamber G via the air valve 16. The air chamber G expands and contracts as the tube member 1 expands and contracts, and the compression ratio of the air chamber G can be determined by the amount of hydraulic oil stored in the reservoir R. And the spring characteristic by an air spring can be set to a desired characteristic by adjusting the pressure when the air chamber G is in a predetermined volume by supply and discharge of gas.

  The shock absorber main body D accommodated in the tube member 1 has a cylindrical cylinder 3 held in a state suspended from the cap member 13 via a cylinder holding cylinder 17 and is movable in the axial direction within the cylinder 3. A piston 4 to be inserted, a rod 5 which is connected to the piston 4 and extends downward in FIG. 1 and protrudes from the cylinder 3 and whose lower end is fixed to the wheel-side bracket 12, and is fixed to the lower end in FIG. An annular rod guide 6 that pivotally supports the rod 5 so as to be movable in the axial direction, and a base rod 7 that is held in a state of being suspended from the cap member 13 and stands on the axial center of the cylinder 3 on the side opposite to the rod. A base member 8 fixed to the lower end in FIG. 1 of the base rod 7 and a free piston 9 attached to the outer periphery of the base rod 7 and capable of moving in the cylinder 3 in the axial direction are provided.

  In the cylinder 3, the lower extension side chamber L 1 in FIG. 1 and the upper pressure side chamber L 2 in FIG. 1, which are partitioned by the piston 4 and filled with hydraulic oil, and the pressure side chamber L 2 are partitioned by the base member 8. A liquid reservoir chamber L3 filled with hydraulic oil and a cylinder internal chamber g2 that is separated from the liquid reservoir chamber L3 by the free piston 9 and accommodates gas are formed. An annular bearing 60 and a seal 61 slidably in contact with the outer peripheral surface of the rod 5 are provided in series on the inner periphery of the rod guide 6, and the seal 61 prevents hydraulic oil in the cylinder 3 from leaking. . An O-ring 90 that is in sliding contact with the outer peripheral surface of the base rod 7 is provided on the inner periphery of the free piston 9, and an O-ring 91 that is in sliding contact with the inner peripheral surface of the cylinder 3 is provided on the outer periphery of the free piston 9. Gas and hydraulic oil can be separated.

  A hole 17a that communicates the inside and outside of the cylinder holding cylinder 17 is formed in the upper part of the cylinder holding cylinder 17 that holds the cylinder 3 in FIG. 1, and the cylinder internal air chamber g2 constitutes an air chamber G together with the reservoir internal air chamber g1. To do. That is, in the present embodiment, the air chamber G extends from the reservoir R outside the shock absorber main body D to the top of the free piston 9 inside the cylinder 3 inside the shock absorber main body D.

  The cylinder internal air chamber g2 has the same pressure as the reservoir internal air chamber g1, and can urge the free piston 9 downward in FIG. 1 by the pressure and pressurize the pressure side chamber L2 and the expansion side chamber L1 via the liquid reservoir chamber L3. . For this reason, damping force generation responsiveness can be improved. The cylinder internal chamber g2 and the reservoir internal chamber g1 may be separated. In this case, in addition to the air valve 16 that supplies and discharges gas to the reservoir internal chamber g1, gas is supplied to and discharged from the cylinder internal chamber g2. It is preferable to provide an air valve. Further, it is possible to improve the damping force generation responsiveness by urging the free piston 9 with a coil spring.

  The piston 4 is formed with an extension side piston passage 4a and a pressure side piston passage 4b communicating with the extension side chamber L1 and the pressure side chamber L2. A leaf valve 40 that opens and closes the expansion side piston passage 4a is laminated on the upper side of the piston 4 in FIG. 1, and the leaf valve 40 opens the expansion side piston passage 4a only during the extension operation. Further, a leaf valve 41 for opening and closing the pressure side piston passage 4b is stacked on the lower side of the piston 4 in FIG. 1, and the leaf valve 41 opens the pressure side piston passage 4b only during the compression operation.

  The base member 8 is formed with an extension side base passage 8a and a pressure side base passage 8b communicating with the pressure side chamber L2 and the liquid reservoir chamber L3. A leaf valve 80 that opens and closes the extension-side base passage 8a is stacked below the base member 8 in FIG. 1, and the leaf valve 80 opens the extension-side base passage 8a only during the extension operation. Further, a leaf valve 81 for opening and closing the pressure side base passage 8b is laminated on the upper side of the base member 8 in FIG. 1, and the leaf valve 81 opens the pressure side base passage 8b only during the compression operation.

  According to the above configuration, the hydraulic oil in the expansion side chamber L <b> 1 that is reduced during the extension operation of the suspension device F in which the wheel side tube 11 is retracted from the vehicle body side tube 10 and the rod 5 is retracted from the cylinder 3 is the leaf of the piston 4. The valve 40 is opened and moved to the compression side chamber L2 expanding through the expansion side piston passage 4a, and the hydraulic oil corresponding to the volume of the rod retreated from the cylinder 3 opens the leaf valve 80 of the base member 8, and the expansion side base passage 8a. The fluid moves from the liquid reservoir L3 to the pressure side chamber L2. For this reason, the shock absorber main body D exhibits the extension side damping force due to the resistance when the hydraulic oil moves through the extension side piston passage 4a and the extension side base passage 8a. Further, when the hydraulic oil flows out from the liquid reservoir L3, the free piston 9 moves downward in FIG. 1 to reduce the liquid reservoir L3 and expand the volume of the cylinder internal chamber g2 to the amount of the rod withdrawal volume. Compensates for cylinder volume changes.

  In the present embodiment, the valve opening pressure of the leaf valve 80 that opens and closes the extension-side base passage 8a is set low, and the leaf valve 80 functions as a check valve. Is mainly caused by the resistance of the leaf valve 40 that opens and closes the expansion side piston passage 4a. By doing in this way, it can suppress that hydraulic oil runs short in the pressure side chamber L2 to expand, However, Resistance by each said leaf valve 40,80 can be suitably changed according to the characteristic of desired damping force. It is. In addition, as a configuration for opening and closing the extension side piston passage 4a and the extension side base passage 8a and giving resistance to the flow of hydraulic oil passing through them, it may be possible to adopt other than the leaf valves 40 and 80, For example, a poppet valve or an orifice may be substituted.

  On the contrary, when the suspension system F is compressed by the suspension device F in which the wheel side tube 11 enters the vehicle body side tube 10 and the rod 5 enters the cylinder 3, the hydraulic oil in the compression side chamber L <b> 2 is reduced through the leaf valve 41 of the piston 4. The hydraulic oil corresponding to the rod volume that has entered the cylinder 3 opens the leaf valve 81 of the base member 8 and moves through the pressure side base passage 8b and moves to the pressure side chamber through the pressure side piston passage 4b. It moves from L2 to the liquid reservoir L3. For this reason, the shock absorber main body D exhibits a compression side damping force due to the resistance when the hydraulic oil moves through the compression side piston passage 4b and the compression side base passage 8b. Further, when the hydraulic oil flows into the liquid reservoir L3, the free piston 9 moves upward in FIG. 1 to enlarge the liquid reservoir L3 and reduce the volume of the cylinder internal air chamber g2 to reduce the cylinder entry volume cylinder. Can compensate for changes in internal volume.

  In the present embodiment, the valve-opening pressure of the leaf valve 41 that opens and closes the compression-side piston passage 4b is set low, and the leaf valve 41 functions as a check valve. This is mainly due to the resistance of the leaf valve 81 that opens and closes the pressure-side base passage 8b. By doing in this way, it can suppress that hydraulic oil runs short in the expansion side chamber L1 which expands, However, Resistance by each said leaf valve 41 and 81 can be suitably changed according to the characteristic of desired damping force. It is. Further, as a configuration for opening and closing the pressure-side piston passage 4b and the pressure-side base passage 8b and for imparting resistance to the flow of hydraulic oil passing through them, a configuration other than the leaf valves 41 and 81 may be employed. Poppet valves and orifices may be substituted.

  Between the piston 4 and the rod guide 6, there is provided an elastic body 2 that exerts a reaction force that cancels the reaction force of the air spring when the suspension device F is fully extended. As shown in FIG. 2, the elastic body 2 includes a two-stage coil spring, that is, a two-stage coil spring, a first coil portion 2a having a small pitch P and a small spring constant, and the first coil portion 2a. And a second coil portion 2b having a larger pitch P and a larger spring constant than the first coil portion 2a. Further, the first coil part 2a having a small spring constant is set so as to be compressed most first in the process of the elastic body 2 compressing.

  When the compression amount of the elastic body 2 when the first coil portion 2a is most compressed is X, the spring constant of the elastic body when the compression amount of the elastic body 2 is less than X (natural length) is less than X. The spring constant of the first coil portion 2a and the spring constant of the second coil portion 2b are combined, and the spring constant of the elastic body 2 when the compression amount of the elastic body 2 is X or more is the spring constant of the second coil portion 2b. It becomes.

  As shown in FIG. 1, annular holders 20 and 21 each having a center hole that allows the rod 5 to be inserted are fitted to the end portions of the elastic body 2 in the axial direction. A holder 20 fitted to the lower end of the elastic body 2 in FIG. 1 is fixed to the rod guide 6. On the other hand, the holder 21 fitted to the upper end portion in FIG. 1 of the elastic body 2 can slide in the cylinder 3 in the axial direction. An annular stopper 50 is fixed to the outer periphery of the rod 5 on the lower side of the piston 4 in FIG. 1 so that the holder 21 can come into contact with the stopper 50 and compress the elastic body 2 when the suspension device F extends to some extent. It has become. Thus, when the elastic body 2 is compressed between the upper and lower holders 21 and 20, the elastic body 2 exerts a reaction force corresponding to the compression amount, and the reaction force by the elastic body 2 compresses the suspension device F. It acts in the direction to be caused (solid line b in FIG. 3, dashed line b). The amount of compression of the elastic body 2 assembled to the suspension apparatus F becomes the largest when the suspension apparatus F is fully extended, becomes zero near the center of the entire stroke range of the suspension apparatus F, and the elastic body 2 extends completely. ing.

  By the way, even when the suspension device F is fully extended, the air chamber G is in a pressurized state, and a reaction force by the air spring acts in a direction in which the suspension device F is extended (solid line a, broken line a in FIG. 3). ). Then, when the suspension device F is fully extended, the reaction force of the air spring acting in the extension direction is canceled by the reaction force of the elastic body 2 acting in the compression direction, and the load applied to the suspension device F is zero, or It is set to be a value close to zero (solid lines a and b in FIG. 3B). By doing in this way, the synthetic | combination characteristic of the spring characteristic of the elastic body 2 and the spring characteristic of an air spring can be closely approached to the spring characteristic of the suspension spring which consists of a coil spring.

  In the present embodiment, an extending spring S made of a coil spring having a coil diameter smaller than that of the elastic body 2 and a short axial length is provided inside the elastic body 2. The extension spring S is compressed to exert a reaction force when the suspension device F is in the vicinity of the maximum extension, and the reaction force by the extension spring S acts in a direction in which the suspension device F is compressed (see FIG. 3 solid line c, two-dot chain line c). By providing the extension spring S, when the spring characteristics of the air spring, the elastic body 2 and the extension spring S are combined, a load is applied to the suspension device F in the compression direction within a predetermined stroke range near the maximum extension. Therefore, the extension operation of the suspension device F can be suppressed, and the impact at the maximum extension time of the suspension device F can be reduced.

  Hereinafter, the operation of the suspension device F according to the present embodiment will be described.

  As shown by the combined lines a, b, and c in FIG. 3 (c), the spring of the suspension device F in the stroke range E1 from the maximum extension of the suspension device F until the extension spring S is fully extended to the natural length. The characteristic depends on the spring characteristic a of the air spring, the spring characteristic b of the elastic body 2, and the spring characteristic c of the extending spring S. In the stroke range E1, since the compression amount of the elastic body 2 is set to be equal to or greater than X, the spring constant of the elastic body 2 is the spring constant of the second coil portion 2b, and the spring characteristic of the elastic body 2 is It depends on the characteristics of the two-coil part 2b.

  Subsequently, in the stroke range E2 until the elastic body 2 extends to the natural length after the extension spring S has become the natural length, the spring characteristics of the suspension device F are the spring characteristics a and the elasticity of the air spring. Depends on the spring characteristic b of the body 2. In the stroke range E2, in the first half region E2a where the compression amount of the elastic body 2 exceeds X, the first coil portion 2a is in the most compressed state. The spring constant of the coil part 2b is obtained, and the spring characteristic of the elastic body 2 depends on the spring characteristic of the second coil part 2b. On the other hand, in the stroke range E2, in the latter half region E2b where the compression amount of the elastic body 2 is X or less, the first coil portion 2a can be expanded and contracted, so that the spring constant of the elastic body 2 is the first in series. The spring constant of the coil part 2a and the second coil part 2b is combined to be small.

  Subsequently, in the stroke range E3 after the elastic body 2 becomes a natural length, the spring characteristic of the suspension device F depends on the spring characteristic a of the air spring, but as described above, the spring characteristic is elastic in the front stroke range E2. The spring constant of the body 2 changes in the middle, and the spring constant of the elastic body 2 in the region (E2b) immediately before the stroke range E3 is reduced to reduce the inclination. The change in the spring constant can be reduced. Therefore, the change in the spring characteristics of the suspension device F as a whole can be moderated, and the riding comfort of the vehicle can be improved.

  Hereinafter, the effect of the suspension apparatus F which concerns on this Embodiment is demonstrated.

  In the present embodiment, the second coil portion 2b of the elastic body 2 has a larger pitch P and a larger spring constant than the first coil portion 2a.

  According to the above configuration, in the elastic body 2 using a multistage coil spring, when the elastic body 2 is compressed, it is easy to compress the first coil portion 2a before the second coil portion 2b. The multi-stage coil spring can be easily designed. The configuration of the multi-stage coil spring serving as the elastic body 2 is not limited to the above, and the pitch P of the coil portion having a small spring constant may be larger than the pitch P of the coil portion having a large spring constant. You may make it compress the coil part with a large spring constant ahead of a small coil part.

  In the present embodiment, the elastic body 2 includes a two-stage multi-stage coil spring, and includes a first coil portion 2a and a second coil portion 2b that is connected to the first coil portion 2a. . And when the elastic body 2 is compressed, the 1st coil part 2a is most compressed ahead of the 2nd coil part 2b.

  According to the said structure, the spring constant of the elastic body 2 when the compression amount of the elastic body 2 is smaller than predetermined | prescribed, ie, the elastic body 2 exists in the state extended more than predetermined, can be lowered | hung. For this reason, in the case where the elastic body 2 is fully extended in the middle of the entire stroke range where the spring constant of the air spring is not so large as in the present embodiment, and the spring characteristic of the air spring only is switched, It is possible to effectively moderate the change in the spring characteristics of the suspension device F at the end of the stretch.

  Moreover, according to the said structure, since the spring constant of the elastic body 2 can be changed on the way with one multistage coil spring, the number of parts of the suspension apparatus F can be reduced, and a structure is simplified. Can do. In the present embodiment, the elastic body 2 is composed of a two-stage coil spring, but may be composed of a multi-stage coil spring having three or more stages.

  The configuration of the elastic body 2 is not limited to the above, and the elastic body 2 includes a plurality of coil springs arranged in series or in parallel, and when the elastic body 2 extends, one coil spring is the other coil spring. You may make it extend ahead. Also in this case, the spring constant of the elastic body 2 can be changed in the middle, and the spring constant of the elastic body 2 can be lowered in a region where the compression amount of the elastic body 2 is smaller than a predetermined value.

  Further, in the present embodiment, the suspension device F includes the telescopic tube member 1 including the vehicle body side tube 10 and the wheel side tube 11, and the tube member 1 is sealed while gas is compressed in the tube member 1. 1 includes an air spring that exerts a reaction force corresponding to the compression amount of 1 and an elastic body 2 that exerts a reaction force that counteracts the reaction force of the air spring at the maximum extension, and the spring constant of the elastic body 2 Changes on the way.

  According to the above configuration, since the spring constant of the elastic body 2 is changed in the middle, the change in the spring characteristics of the suspension device F bordered by the extension of the elastic body 2 is moderated, and the riding comfort of the vehicle is improved. It becomes possible.

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

F suspension device P pitch 1 tube member 2 elastic body 2a first coil part 2b second coil part 10 vehicle body side tube 11 wheel side tube

Claims (4)

  A telescopic tube member composed of a vehicle body side tube and a wheel side tube, an air spring that encloses the tube member while compressing gas and exerts a reaction force according to the compression amount of the tube member, and maximum extension And a resilient member that exerts a reaction force that counteracts the reaction force of the air spring at the time, and the spring constant of the resilient member changes midway.   The elastic body includes a multi-stage coil spring, and includes a first coil portion and a second coil portion that is continuous with the first coil portion. When the elastic body is compressed, the first coil The suspension device according to claim 1, wherein the portion is most compressed before the second coil portion.   The suspension device according to claim 2, wherein the second coil part has a larger pitch and a larger spring constant than the first coil part. The elastic body is composed of a plurality of coil springs arranged in series or in parallel, and when the elastic body extends, one of the coil springs extends before the other coil spring. Item 2. The suspension device according to item 1.

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