Suspension device and rear cushion unit

Abstract

A suspension device (S) according to the present invention is provided with: a suspension spring (30) that supports a vehicle body (F) of a vehicle (M); a movable spring seat (31) that supports one end of the suspension spring (30) and is displaceable in the direction in which the suspension spring (30) expands and contracts; a housing (32) that forms a pressure chamber (P) in which a liquid is contained between the housing (32) and the movable spring seat (31), the housing (32) allowing for movement of the movable spring seat (31) in the direction in which the suspension spring (30) expands and contracts; a stopper (33) that, when the pressure chamber (P) is maximized by the movement of the movable spring seat (31) toward the suspension spring side relative to the housing (32), prevents further movement of the movable spring seat (31) toward the suspension spring side; and an elastic pressurization means (34) that can pressurize the inside of the pressure chamber (P) with elastic force and can adjust the elastic force.

Description

Suspension system and rear cushion unit

[0001] The present invention relates to a suspension system and a rear cushion unit.

[0002] The suspension device, together with the shock absorber body, constitutes a rear cushion unit, which is used, for example, by being interposed between the body and rear wheel of a saddle-ride type vehicle, and elastically supports the body.

[0003] Furthermore, as disclosed in JP2021-11875A, for example, a rear cushion unit is configured with a shock absorber body including a cylinder, a piston movably inserted into the cylinder and dividing the cylinder into an extension-side chamber and a compression-side chamber filled with hydraulic oil, a rod movably inserted into the cylinder and connected to the piston, and a suspension device including a suspension spring interposed between a spring bearing attached to the outer periphery of the cylinder and a spring bearing attached to the outer periphery of the tip of the rod.When the rear cushion unit configured in this way is interposed between the vehicle body and the rear wheel, it elastically supports the vehicle body with the suspension spring and can suppress vibration between the vehicle body and the rear wheel by the damping force generated by the shock absorber body against relative movement between the vehicle body and the rear wheel in the up-down direction.

[0004] JP2021-11875A

[0005] Conventional suspension systems allow adjustment of vehicle height by changing the support position of the suspension spring on the cylinder side spring bearing, but since the spring constant of the suspension spring cannot be changed, there is room for improvement in the ride comfort of the vehicle.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a suspension system and a rear cushion unit that can improve the ride comfort of a vehicle.

[0007] In order to solve the above problem, the suspension device of the present invention comprises a suspension spring that supports the body of a vehicle, a movable spring bearing that supports one end of the suspension spring and is displaceable in the direction in which the suspension spring expands and contracts, a housing that allows the movable spring bearing to move in the direction in which the suspension spring expands and contracts and forms a pressure chamber that contains liquid between the movable spring bearing and the movable spring bearing, a stopper that prevents the movable spring bearing from moving further toward the suspension spring when the movable spring bearing moves toward the suspension spring relative to the housing and the pressure chamber becomes maximum, and elastic pressure means that can pressurize the pressure chamber with an elastic force and that can adjust the elastic force.

[0008] In a suspension device configured in this manner, the elastic pressurizing means applies pressure to the pressure chamber with its elastic force, and one end of the suspension spring is supported by the movable spring bearing, so that the movable spring bearing can be fixed immovably in a position restricted by the stopper by adjusting the pressure that the elastic pressurizing means applies to the pressure chamber, and the movable spring bearing can be displaced relative to the housing according to the degree of contraction of the suspension spring. Furthermore, because the elastic pressurizing means applies pressure to the pressure chamber with its elastic force, when the movable spring bearing is displaced relative to the housing, the movable spring bearing receives the elastic force of the elastic pressurizing means and functions as a spring together with the suspension spring, so that the spring constant of the suspension device decreases.

[0009] Fig. 1 is a cross-sectional view of a rear cushion unit equipped with a suspension device according to an embodiment of the present invention, and Fig. 2 is a view showing the rear cushion unit attached to a saddle-ride type vehicle.

[0010] The present invention will be described based on the embodiment shown in the drawings. As shown in Figures 1 and 2, a suspension device S in one embodiment is integrated with a shock absorber main body D and, together with the shock absorber main body D, constitutes a rear cushion unit RCU, which is interposed between a vehicle body F and a rear wheel W of a saddle-ride type vehicle M, such as a motorcycle, to elastically support the vehicle body F. Note that in this embodiment, the suspension device S is described using an example in which the suspension device S is applied to the rear cushion unit RCU and interposed between the vehicle body F and the rear wheel W of the saddle-ride type vehicle M, but the suspension device S may be used in vehicles other than the saddle-ride type vehicle M, either together with the shock absorber main body D or separately from the shock absorber main body D.

[0011] Hereinafter, each part of the suspension S and the rear cushion unit RCU equipped with the suspension S will be described in detail. First, as shown in Fig. 1 , the shock absorber main body D in the rear cushion unit RCU includes a cylinder 1, a cylindrical rod 2 inserted into the cylinder 1 so as to be movable in the axial direction, a piston 3 connected to the rod 2 and inserted into the cylinder 1 so as to be movable in the axial direction, and dividing the interior of the cylinder 1 into an expansion-side chamber R1 and a compression-side chamber R2, an outer shell 4 covering the outer periphery of the cylinder 1 and forming an annular gap between it and the cylinder 1, a cap 5 attached to the outer periphery of the upper end of the outer shell 4 in Fig. 1 and closing the upper end of the cylinder 1 in Fig. 1, and a tank 6 held by the cap 5.

[0012] The cylinder 1 is provided with a flange 1a on the outer periphery of its upper end in FIG. 1 and abutting against the upper end of the outer shell 4, a flange 1b on the outer periphery of its lower end in FIG. 1 and fitting into the inner periphery of the outer shell 4, and a hole 1c provided above and in close proximity to the flange 1b and communicating the inside and outside of the cylinder 1.

[0013] The interior of the cylinder 1 is divided into an expansion-side chamber R1 and a compression-side chamber R2 filled with hydraulic oil by a piston 3 inserted movably in the axial direction. The piston 3 is annular and attached to the outer periphery of the tip of a rod 2 inserted movably in the axial direction into the cylinder 1, and is provided with an expansion-side port 3a and a compression-side port 3b that communicate between the expansion-side chamber R1 and the compression-side chamber R2. An annular expansion-side leaf valve 13 that opens and closes the expansion-side port 3a is stacked at the upper end of the piston 3 in FIG. 1, and an annular compression-side leaf valve 14 that opens and closes the compression-side port 3b is stacked at the lower end of the piston 3 in FIG. 1. The inner peripheries of the extension-side leaf valve 13 and the compression-side leaf valve 14 are both fixed to the outer periphery of the rod 2, and by bending their outer peripheries, they open the corresponding expansion-side port 3a and compression-side port 3b and provide resistance to the flow of hydraulic oil passing through them.

[0014] 1 is in contact with the lower end of the flange 1a above the cylinder 1, and together with the cylinder 1, an annular gap is formed between the flanges 1a and 1b on the outer periphery of the cylinder 1. A hole 4a is provided near the upper end of the outer shell 4, which communicates between the inside and outside of the outer shell 4 and leads to the annular gap, and a threaded portion 4b is formed on the outer periphery of the outer shell 4 below the hole 4a in FIG.

[0015] 1 , an annular rod guide 7 is attached to the inner periphery of the lower end of the outer shell 4. The rod 2, which is axially movable within the cylinder 1, is inserted into the rod guide 7. An annular bushing 8 that slides against the outer periphery of the rod 2 to guide the axial movement of the rod 2, and a seal ring 9 that seals the outer periphery of the rod 2 are attached to the inner periphery of the rod guide 7. A seal ring 10 that tightly contacts the inner periphery of the outer shell 4 is attached to the outer periphery of the rod guide 7. In this way, the gap between the rod 2 and the rod guide 7 is sealed by the seal ring 9, and the gap between the rod guide 7 and the outer shell 4 is sealed by the seal ring 10, so that the insides of the cylinder 1 and the outer shell 4 are airtight.

[0016] 1, a bracket 20 connectable to a swing arm SA that holds a rear wheel W of a saddle-ride type vehicle M is provided, and an annular bump cushion 21 supported by the bracket 20 is attached to the outer periphery of the rod 2 at the lower end in FIG. 1, which is the end opposite the outer shell. On the other hand, an annular bump stopper 22 axially facing the bump cushion 21 is attached to the inner periphery of the lower end of the outer shell 4. Therefore, when the rod 2 approaches the outer shell 4 in the axial direction and the shock absorber main body D contracts near the stroke end on the contraction side, the bump cushion 21 comes into contact with the bump stopper 22 and is compressed, generating a repulsive force that prevents the shock absorber main body D from contracting further.

[0017] The cap 5 is a closed-topped cylinder having a cylindrical portion 5a and a bottom portion 5b, and the cylindrical portion 5a is screwed onto the threaded portion 4b of the outer shell 4. When the cap 5 is screwed onto the outer shell 4 in this manner, the flange 1a of the cylinder 1 is clamped between the outer shell 4 and the bottom portion 5b of the cap 5, and the cylinder 1 is fixedly secured to the outer shell 4 and the cap 5. The cylindrical portion 5a has a smaller diameter at its lower end in FIG. 1 than at its upper end, and has a step 5a1 on its outer periphery.

[0018] The cap 5 also has a bracket 5c at the upper end of the bottom portion 5b that can be connected to the body F of the saddle-ride type vehicle M, and a tank holding portion 5d that holds the tank 6 on the side of the upper end of the cylindrical portion 5a in Figure 1.

[0019] The tank 6 held in the tank holding portion 5d is divided into an oil chamber O filled with hydraulic oil and a gas chamber G filled with gas by a free piston 6a housed therein so as to be axially movable. The oil chamber O is connected to the compression-side chamber R2 through a passage 11 formed from the bottom 5b of the cap 5 to the tank holding portion 5d, and is also connected to the extension-side chamber R1 through a passage 12 formed from the cylindrical portion 5a of the cap 5 to the tank holding portion 5d, the hole 4a of the outer shell 4, the annular gap, and the hole 1c of the cylinder 1. The interior of the tank 6 may be divided into the oil chamber O and the gas chamber G by a flexible bladder, bellows, or the like, instead of the free piston 6a.

[0020] Further, an extension side soft valve 15 and a compression side soft valve 16 are provided in parallel with the passage 12, and an on-off valve 17 is provided in series with the extension side soft valve 15 and the compression side soft valve 16. The resistance that the extension side soft valve 15 imparts to the flow of hydraulic oil is smaller than the resistance that the extension side leaf valve 13 imparts to the flow of hydraulic oil, and the resistance that the compression side soft valve 16 imparts to the flow of hydraulic oil is smaller than the resistance that the compression side leaf valve 14 imparts to the flow of hydraulic oil. Further, the on-off valve 17 opens when energized to enable the passage 12, and closes when not energized to shut off the passage 12.

[0021] The shock absorber body D is configured as described above, and when the shock absorber body D performs an extension operation with the on-off valve 17 closed, hydraulic oil in the extension-side chamber R1, which is reduced in size as the piston 3 moves downward in FIG. 1 , passes through the extension-side port 3a and the extension-side leaf valve 13 and moves to the compression-side chamber R2, which is expanded. Because the on-off valve 17 is closed, the hydraulic oil in the extension-side chamber R1 cannot pass through the passage 12, so the entire flow of hydraulic oil from the extension-side chamber R1 to the compression-side chamber R2 flows through the extension-side leaf valve 13. Therefore, the shock absorber body D generates a hard damping force that hinders the extension operation only by the extension-side leaf valve 13. During the extension operation of the shock absorber body D, the rod 2 retreats from the cylinder 1, leaving a shortage of hydraulic oil in the cylinder 1 by the volume of the rod 2 retreating from the cylinder 1. However, the shortage of hydraulic oil is supplied from the tank 6 through the passage 11 into the cylinder 1, thereby compensating for the volume of the rod 2.

[0022] On the other hand, when the shock absorber main body D contracts with the on-off valve 17 closed, the hydraulic oil in the compression-side chamber R2, which is reduced in size by the upward movement of the piston 3 in FIG. 1, passes through the compression-side port 3b and the compression-side leaf valve 14 and moves to the expansion-side chamber R1. Because the on-off valve 17 is closed and the hydraulic oil in the compression-side chamber R2 cannot pass through the passage 12, the entire flow rate of hydraulic oil from the compression-side chamber R2 to the expansion-side chamber R1 flows through the compression-side leaf valve 14. Therefore, the shock absorber main body D generates a hard damping force that hinders the contraction operation only by the compression-side leaf valve 14. When the shock absorber main body D contracts, the rod 2 enters the cylinder 1, and an excess amount of hydraulic oil corresponding to the volume of the rod 2 entering the cylinder 1 is generated in the cylinder 1. However, the excess hydraulic oil is discharged from the cylinder 1 into the tank 6 through the passage 11, thereby compensating for the volume of the rod 2.

[0023] When the shock absorber body D extends with the on-off valve 17 open, the hydraulic oil in the expansion-side chamber R1, which is reduced in size by the downward movement of the piston 3 in FIG. 1, can move to the expansion-side chamber R2, which is expanded, through not only the expansion-side port 3a but also the expansion-side soft valve 15 of the passage 12. Since the resistance that the expansion-side soft valve 15 imparts to the flow of hydraulic oil is smaller than the resistance that the extension-side leaf valve 13 imparts to the flow of hydraulic oil, the hydraulic oil preferentially passes through the expansion-side soft valve 15. Therefore, the shock absorber body D generates a soft damping force that hinders the expansion operation mainly by the expansion-side soft valve 15.

[0024] On the other hand, when the shock absorber main body D contracts with the on-off valve 17 open, the hydraulic oil in the compression-side chamber R2, which is contracted by the upward movement of the piston 3 in FIG. 1, can move to the expanded extension-side chamber R1 through not only the compression-side port 3b and the compression-side leaf valve 14 but also the compression-side soft valve 16 of the passage 12. Because the resistance that the compression-side soft valve 16 imparts to the flow of hydraulic oil is smaller than the resistance that the compression-side leaf valve 14 imparts to the flow of hydraulic oil, the hydraulic oil preferentially passes through the compression-side soft valve 16. Therefore, the shock absorber main body D generates a soft damping force that hinders the contraction operation mainly by the compression-side soft valve 16.

[0025] In this way, the shock absorber main body D can switch between soft and hard damping force during expansion and contraction by opening and closing the on-off valve 17. Note that the specific structure of the shock absorber main body D is one example, and is not limited to the structure described above as long as it is capable of generating damping force during expansion and contraction. Therefore, the shock absorber main body D may adopt, for example, a structure in which a reservoir is provided between the outer shell 4 and the cylinder 1, or a single-cylinder structure in which the cylinder 1 is eliminated and the piston 3 is in sliding contact with the inner periphery of the outer shell 4.

[0026] Next, the suspension device S comprises a suspension spring 30, a movable spring bearing 31 that supports one end of the suspension spring 30, which is the upper end in Figure 1, and is movable in the direction in which the suspension spring 30 expands and contracts, a housing 32 that is attached to the outer periphery of the cap 5 and allows the movable spring bearing 31 to move in the direction in which the suspension spring 30 expands and contracts, while forming a pressure chamber P that contains liquid between the movable spring bearing 31 and the housing 32, a stopper 33 that prevents the movable spring bearing 31 from moving further toward the suspension spring when the movable spring bearing 31 moves toward the suspension spring relative to the housing 32 and the pressure chamber P becomes maximum, and an elastic pressure means 34 that can pressurize the pressure chamber P with an elastic force and can adjust the elastic force.

[0027] The suspension spring 30 is a coil spring, and one end, which is the upper end in FIG. 1 , is supported by a movable spring bearing 31, while the other end, which is the lower end in FIG. 1 , is supported by a fixed spring bearing 25 attached to a bracket 20 provided at the lower end in FIG. 1 of the rod 2 of the shock absorber main body D. The suspension spring 30 is interposed in a compressed state between the movable spring bearing 31 and the fixed spring bearing 25, and constantly urges the shock absorber main body D in the extension direction. When the rear cushion unit RCU is interposed between the body F and rear wheel W of the saddle-ride type vehicle M, the suspension spring 30 contracts slightly under the weight of the body F, elastically supporting the body F. Therefore, when the shock absorber main body D expands or contracts due to vibrations input from the road surface while the saddle-ride type vehicle M is traveling, the suspension spring 30 also expands or contracts together with the shock absorber main body D.

[0028] The movable spring bearing 31 is cylindrical and includes a large-diameter portion 31a having a large inner and outer diameter on the suspension spring side, a small-diameter portion 31b having an inner and outer diameter on the opposite side from the suspension spring that is smaller than the inner and outer diameters of the large-diameter portion 31a, and a flange-shaped pressure-receiving portion 31c connecting the large-diameter portion 31a and the small-diameter portion 31b. The inner diameter of the small-diameter portion 31b, which is the smallest inner diameter of the movable spring bearing 31, is larger than the outer diameter of the small-diameter portion at the lower end of the cylindrical portion 5a of the outer shell 4 and the cap 5. This allows the movable spring bearing 31 to move in the vertical direction in FIG. 1 , which is the direction in which the suspension spring 30 expands and contracts, without interfering with the outer shell 4 and the cap 5. The inner periphery of the small-diameter portion 31b may be in sliding contact with the outer periphery of the small-diameter portion of the cylindrical portion 5a of the cap 5. In the movable spring bearing 31 of this embodiment, the outer diameter of the pressure-receiving portion 31c is larger than the outer diameter of the large-diameter portion 31a. Furthermore, a seal ring 31d is fitted in an annular groove (not shown) provided on the outer periphery of the pressure receiving portion 31c of the movable spring bearing 31.

[0029] 1 of the large diameter portion 31a of the movable spring bearing 31 and the upper end of the suspension spring 30. The seat ring 35 includes a fitting portion 35a that fits onto the inner periphery of the suspension spring 30, a flange-shaped seat portion 35b that is provided on the outer periphery of the upper end of the fitting portion 35a in FIG. 1 and abuts against the upper end of the suspension spring 30 in FIG. 1, and an annular positioning portion 35c that curves from the outer periphery of the seat portion 35b toward the large diameter portion and is loosely fitted onto the outer periphery of the large diameter portion 31a. When the seat portion 35b is stacked on the end of the large diameter portion 31a, the seat ring 35 is allowed to rotate circumferentially relative to the movable spring bearing 31, but the positioning portion 35c faces the outer periphery of the large diameter portion 31a and does not come off radially relative to the movable spring bearing 31. Because the suspension spring 30 is a coil spring, its end rotates slightly in the circumferential direction as it expands and contracts, but by laminating a sheet ring 35 that can rotate in the circumferential direction on the movable spring bearing 31, it is possible to prevent the rotation of the suspension spring 30 from being transmitted to the movable spring bearing 31. The movable spring bearing 31 is provided with a seal ring 31d to form a pressure chamber P together with the housing 32 and is therefore difficult to rotate in the circumferential direction, so providing the sheet ring 35 in this manner prevents the movable spring bearing 31 from rotating and prevents deterioration of the seal ring 31d. Note that the sheet ring 35 can be omitted if not necessary, and the suspension spring 30 may be placed in direct contact with the end of the movable spring bearing 31.

[0030] The housing 32 includes an annular base 32a that abuts against the step 5a1 on the outer periphery of the cap 5, and an annular socket 32b that hangs down from the outer periphery of the lower end of the base 32a in FIG. 1 . When the housing 32 is attached to the cap 5 while being disposed on the outer periphery of the tubular portion 5a of the cap 5 and abutting against the step 5a1, an annular gap is formed between the housing 32 and the tubular portion 5a of the cap 5 into which the small-diameter portion 31b of the movable spring bearing 31 can be inserted, and an annular space is formed within the socket 32b into which the pressure-receiving portion 31c and large-diameter portion 31a of the movable spring bearing 31 can be inserted. In this manner, the housing 32 and the movable spring bearing 31 are attached to the outer shell 4 via the cap 5 or another component connected to the outer shell 4. The housing 32 and the movable spring bearing 31 may be attached to the outer shell 4 via the cap 5 or another component connected to the outer shell 4, or they may be attached directly to the outer shell 4.

[0031] The base 32a has an inner diameter set to a diameter that allows it to slide against the outer periphery of the small diameter portion 31b of the movable spring bearing 31, and is fixed to the cap 5 while abutting against the step 5a1 of the cap 5. A seal ring 32c that slides against the outer periphery of the small diameter portion 31b of the movable spring bearing 31 is installed in an annular groove (not shown) provided on the inner periphery of the base 32a. The pressure receiving portion 31c of the movable spring bearing 31 is slidably inserted into the socket 32b, and a seal ring 31d on the outer periphery of the pressure receiving portion 31c provides a seal between the socket 32b and the pressure receiving portion 31c. When the movable spring bearing 31 is inserted into the housing 32, the outer periphery of the pressure receiving portion 31c slides against the inner periphery of the socket 32b, and the outer periphery of the small diameter portion 31b slides against the inner periphery of the base 32a, so that the movable spring bearing 31 can move in the axial direction (up and down in FIG. 1 ) without axial wobble while being guided by the housing 32. In addition, an opposing surface 31c1, which is the lower end surface in Figure 1 of the pressure-receiving portion 31c of the movable spring bearing 31, and an opposing surface 32a2, which is the upper end surface in Figure 1 of the base 32a of the housing 31, are opposed to each other in the axial direction, and when the movable spring bearing 31 moves upward in Figure 1 relative to the housing 32 and approaches each other, and the opposing surfaces 31c1, 32a1 abut against each other, further movement upward in Figure 1, which is the anti-spring bearing side relative to the housing 32, is restricted.

[0032] Furthermore, when the movable spring bearing 31 is inserted into the housing 32, a pressure chamber P is formed between the housing 32 and the movable spring bearing 31 by an annular gap surrounded by the small diameter portion 31b and pressure receiving portion 31c of the movable spring bearing 31 and the base portion 32a and socket 32b of the housing 32. The liquid contained in the pressure chamber P is hydraulic oil in the suspension S of this embodiment, but may be a liquid other than hydraulic oil. The seal rings 31d and 32c seal the space between the movable spring bearing 31 and the housing 32, hermetically sealing the pressure chamber P, thereby preventing the liquid in the pressure chamber P from leaking out of the pressure chamber P.

[0033] Since the pressure in the pressure chamber P acts on the upper end of the pressure-receiving portion 31c of the movable spring bearing 31 in Figure 1, the movable spring bearing 31 is constantly urged toward the suspension spring, which is downward in Figure 1, by a force equal to the area of ​​the pressure-receiving portion 31c at the upper end in Figure 1 that faces the pressure chamber P multiplied by the pressure in the pressure chamber P.

[0034] A stopper 33 is attached to the outer periphery of the socket 32b of the housing 32. The stopper 33 includes a cylindrical portion 33a having a threaded portion on its inner periphery and screwed onto the outer periphery of the socket 32b, and an annular stopper portion 33b extending radially from the inner periphery of the cylindrical portion 33a. The inner diameter of the stopper portion 33b is larger than the outer diameter of the large-diameter portion 31a of the movable spring bearing 31 but smaller than the inner diameter of the socket 32b. When the stopper 33 is attached to the socket 32b of the housing 32, the inner periphery of the stopper portion 33b axially faces the outer periphery of the lower end of the pressure-receiving portion 31c of the movable spring bearing 31 in FIG. 1. When the movable spring bearing 31 moves maximally toward the suspension spring relative to the housing 32, the stopper portion 33b of the stopper 33 abuts against the outer periphery of the lower end of the pressure receiving portion 31c of the movable spring bearing 31, preventing the movable spring bearing 31 from further displacing from the housing 32 toward the suspension spring, which is downward in Figure 1. In this way, when the movable spring bearing 31 moves toward the suspension spring relative to the housing 32 to maximize the pressure chamber P, the stopper 33 prevents the movable spring bearing 31 from further moving toward the suspension spring. Therefore, the movable spring bearing 31 can stroke from a position where the pressure receiving portion 31c abuts against the base portion 32a of the housing 32, minimizing the pressure chamber P, to a position where the pressure receiving portion 31c abuts against the stopper portion 33b of the stopper 33, maximizing the pressure chamber P.

[0035] As described above, the movable spring bearing 31 has the large diameter portion 31a, the small diameter portion 31b, and the pressure receiving portion 31c, and the housing 32 has the base 32a that is in sliding contact with the outer periphery of the small diameter portion 31b, and the socket 32b that hangs down from the base 32a and into whose inner periphery the pressure receiving portion 31c is slidably inserted, so that the sliding surfaces of both the housing 32 and the movable spring bearing 31 that moves in and out of the housing 32 are not exposed to the outside of the suspension S. Therefore, according to the suspension S that has the movable spring bearing 31 and housing 32 configured as described above, the sliding surfaces of both the movable spring bearing 31 and the housing 32 can be protected, and leakage of liquid from within the pressure chamber P can be prevented. Furthermore, the inner peripheral surface of the stopper portion 33b of the stopper 33 faces the outer peripheral surface of the large diameter portion 31a of the movable spring bearing 31, and not only functions as a stopper that restricts the movement of the movable spring bearing 31, but also covers the open end at the lower end of the housing 32 in Figure 1, thereby preventing dust and water from entering the housing 32. Note that the movable spring bearing 31 may be attached to the outer periphery of the housing 32 as long as it can form a pressure chamber P between itself and the housing 32 and can move relative to the housing 32 in the direction in which the suspension spring 30 expands or contracts.

[0036] The elastic pressure applying means 34 for adjusting the pressure in the pressure chamber P comprises a container 37, a movable partition 38 that is movably inserted into the container 37 and forms a space in the container 37 that is connected to the pressure chamber P via the piping 36, and an elastic partition 39 that divides the space into an air chamber A filled with gas and a liquid chamber B that is connected to the pressure chamber P.

[0037] The container 37 is cylindrical, and one end of the container 37 is closed by a cap 40 that holds an elastic partition wall 39 formed by a bladder. A threaded cap 41 is attached to the other end of the container 37. A screw shaft 42, the tip of which protrudes into the container 37, is threadedly attached to the inner periphery of the threaded cap 41. A nut 43 is threadedly attached to the outer periphery of the screw shaft 42. When the nut 43 is rotated relative to the screw shaft 42 and is brought into contact with the threaded cap 41, and then further tightened, the threaded cap 41 and the nut 43 act as a double nut to prevent rotation of the screw shaft 42 and secure the screw shaft 42 to the threaded cap 41. Furthermore, when the nut 43 is loosened while the screw shaft 42 is fixed to the threaded cap 41, the screw shaft 42 is allowed to rotate relative to the threaded cap 41, and the rotation of the screw shaft 42 relative to the threaded cap 41 allows the screw shaft 42 to move in the axial direction relative to the container 37. The screw shaft 42 has a head 42a at its rear end that protrudes outside the container 37, which allows it to be gripped with a tool, and when the head 42a protrudes to the maximum extent into the container 37, it comes into contact with the lower end (in FIG. 1) of the nut 43 that abuts against the threaded cap 41, preventing further penetration into the container 37.

[0038] A movable partition 38 is attached to the tip of the screw shaft 42 and is slidably inserted into the container 37 in the axial direction. The movable partition 38 forms a space within the container 37 that is connected to the pressure chamber P, and is displaced within the container 37 together with the screw shaft 42 as the screw shaft 42 moves in the axial direction relative to the container 37, thereby changing the volume of the space. Note that the means for displacing the movable partition 38 relative to the container 37 may be a mechanism other than a feed screw mechanism composed of the screw shaft 42 and the threaded cap 41, and the design can be modified as appropriate. However, by using a feed screw mechanism, the movable partition 38 can be displaced continuously relative to the container 37 with a small torque, and the pressure within the pressure chamber P can be adjusted continuously by the elastic pressure means 34. Furthermore, the power of an actuator such as a motor or air pressure may be used to displace the movable partition 38 relative to the container 37. Furthermore, the movable partition 38 is a free piston that is inserted freely into the container 37, but any movable partition that can change the volume of the space partitioned by the movable partition 38 inside the container 37, such as a metal bellows, may be used.

[0039] The space within the container 37 is connected to the pressure chamber P through the piping 36. An elastic partition 39 is housed within the space within the container 37, and a gas is filled within the elastic partition 39. The space within the container 37, outside the elastic partition 39, is filled with a liquid. By inserting the movable partition 38 into the container 37, the space partitioned by the movable partition 38 is divided by the elastic partition 39 into an air chamber A filled with a gas and a liquid chamber B filled with a liquid, and the liquid chamber B is connected to the pressure chamber P through the piping 36. The liquid filled in the liquid chamber B may be the same liquid as the liquid filled in the pressure chamber P, and may be, for example, hydraulic oil, an ethylene glycol aqueous solution, or another liquid. The elastic partition 39 may also be a diaphragm or a bellows.

[0040] Because compressed gas is filled in air chamber A within elastic partition wall 39, the pressure within air chamber A acts on pressure chamber P via liquid chamber B. In this way, elastic pressurizing means 34 functions as an air spring, constantly pressurizing pressure chamber P with the elastic force generated by the gas within air chamber A. When movable partition wall 38 is displaced axially within container 37 by rotating screw shaft 42, thereby reducing the volume of the space, the gas within air chamber A is compressed and generates a greater elastic force, thereby increasing the pressure within pressure chamber P. Conversely, when movable partition wall 38 is displaced axially within container 37 by rotating screw shaft 42, thereby increasing the volume of the space, air chamber A expands, reducing the degree of compression of the gas, thereby reducing the elastic force generated by the gas and decreasing the pressure within pressure chamber P.

[0041] Furthermore, when the movable partition 38 penetrates into the container 37 to the maximum extent to minimize the volume of the space, the elastic force of the gas in the air chamber A is maximized, and the pressure that the elastic pressurizing means 34 applies to the pressure chamber P is maximized. In this state, the force that the movable spring bearing 31 receives from the pressure chamber P in the direction to compress the suspension spring 30 is set to be greater than the force that the movable spring bearing 31 receives from the suspension spring 30 in the direction to compress the pressure chamber P when the shock absorber body D is fully compressed and the suspension spring 30 is fully compressed. Therefore, when the movable partition 38 penetrates into the container 37 to the maximum extent to minimize the volume of the space, the force that the movable spring bearing 31 receives from the suspension spring 30 does not displace the movable spring bearing 31 upward in FIG. 1, and it is always located at the lowest position where it abuts against the stopper 33 and does not displace from that position.

[0042] On the other hand, when the movable partition 38 is maximally retracted within the container 37 to maximize the volume of the space, the elastic force of the gas in the air chamber A is minimized, and the pressure that the elastic pressurizing means 34 applies to the pressure chamber P is also minimized. In this state, the force that the movable spring bearing 31 receives from the pressure chamber P in a direction compressing the suspension spring 30 is balanced with the force that the movable spring bearing 31 receives in a direction compressing the pressure chamber P from the compressed suspension spring 30 when a predetermined weight is loaded on the body F of the saddle-riding type vehicle M. The predetermined weight is set to about the weight of one passenger, for example, in the range of 50 kg to 80 kg, and the specifications of the gas pressure in the air chamber A, the pressure-receiving area of ​​the pressure chamber P of the movable spring bearing 31, and the suspension spring 30 are set so that the force that the movable spring bearing 31 receives from the pressure chamber P and the force that the movable spring bearing 31 receives from the suspension spring 30 are balanced when one passenger is riding on the saddle-riding type vehicle M.

[0043] The suspension system S and rear cushion unit RCU configured as described above are provided with elastic pressurizing means 34 that elastically pressurizes pressure chamber P, and when movable partition 38 is positioned within container 37 at a position that minimizes the volume of the space, the gas pressure within air chamber A reaches a maximum and acts within pressure chamber P. In this state, as described above, even if suspension spring 30 is fully compressed within the stroke range of shock absorber body D, the elastic force of suspension spring 30 cannot exceed the force that presses movable spring bearing 31 toward suspension spring 30 due to the action of the pressure in pressure chamber P, and movable spring bearing 31 is not displaced from the position where it is maximally retracted from housing 32 by stopper 33.

[0044] Therefore, when the movable partition 38 is positioned in this way to minimize the volume of space within the container 37, the position of the movable spring bearing 31 does not change, so only the suspension spring 30 expands and contracts in accordance with the expansion and contraction of the shock absorber body D, and the spring constant of the suspension device S becomes the spring constant of the suspension spring 30, which takes on the largest value.

[0045] On the other hand, when the movable partition 38 is positioned to maximize the volume of the space inside the container 37, the pressure of the gas inside the air chamber A is minimized and acts inside the pressure chamber P. In this state, as described above, the force with which the suspension spring 30, which contracts when supporting the body F of the saddle-riding type vehicle M loaded with a predetermined weight, presses the movable spring bearing 31 upward, is balanced with the force with which the movable spring bearing 31 presses toward the suspension spring 30 due to the action of the pressure in the pressure chamber P. Then, when the suspension spring 30, which has contracted when supporting the body F of the saddle-riding type vehicle M loaded with a predetermined weight, further contracts due to vibrations input while the saddle-riding type vehicle M is traveling, the elastic force generated by the suspension spring 30 increases, and the force with which the suspension spring 30 presses the movable spring bearing 31 upward becomes greater than the force with which the movable spring bearing 31 presses toward the suspension spring 30 due to the action of the pressure in the pressure chamber P, and the movable spring bearing 31 is displaced upward in FIG. 1 . 1, the pressure chamber P contracts, liquid is discharged from the pressure chamber P towards the container 37, the volume of the air chamber A contracts, and the force pressing the movable spring bearing 31 towards the suspension spring 30 due to the action of the pressure in the pressure chamber P increases. This upward displacement of the movable spring bearing 31 in FIG. 1 continues until the force pressing the movable spring bearing 31 upward by the suspension spring 30 and the force pressing the movable spring bearing 31 downward towards the suspension spring 30 due to the action of the pressure in the pressure chamber P are balanced. Note that even when the shock absorber main body D contracts, the stroke length is ensured so that the opposing surface 31c1, which is the upper end surface in FIG. 1 of the pressure receiving portion 31c of the movable spring bearing 31, does not come into contact with the opposing surface 32a1, which is the lower end surface in FIG. 1 of the base 32a of the housing 32, until the bump cushion 21 and the bump stopper 22 come into contact with each other. Therefore, when the suspension spring 30, which has contracted by supporting the body F of the saddle-riding vehicle M carrying a predetermined weight, contracts further due to vibrations input while the saddle-riding vehicle M is traveling, the movable spring bearing 31 also displaces relative to the housing 32, so that the body F is elastically supported by the suspension spring 30 connected in series and the elastic pressure means 34 functioning as an air spring, and the spring constant of the suspension device S becomes a spring constant that is the combined spring constant of the suspension spring 30 and the spring constant of the elastic pressure means 34 functioning as an air spring.In this case, if the spring constant of the suspension spring 30 is k1 and the spring constant of the elastic pressure means 34 functioning as an air spring is k2, the spring constant K of the suspension device S is K = k1 · k2 / (k1 + k2), which is smaller than the spring constant k1 when only the suspension spring 30 expands and contracts.

[0046] On the other hand, when the suspension spring 30, which has contracted due to supporting the body F of the saddle-riding vehicle M carrying a predetermined weight, expands due to vibrations input while the saddle-riding vehicle M is traveling, the elastic force of the suspension spring 30 becomes smaller and the movable spring bearing 31 does not displace from the position positioned by the stopper 33, so the spring constant of the suspension device S becomes equal to the spring constant of the suspension spring 30.

[0047] In this way, in the suspension S of the present embodiment and the rear cushion unit RCU to which the suspension S is applied, by adjusting the pressure in the pressure chamber P with the elastic pressurizing means 34, it is possible to switch between a state in which only the suspension spring 30 expands or contracts and a state in which not only the suspension spring 30 but also the movable spring bearing 31 can be displaced relative to the housing 32, thereby adjusting the spring constant of the suspension S. Note that when the movable partition 38 is maximally retracted within the container 37 to maximize the volume of the space, the force that the movable spring bearing 31 receives from the pressure chamber P in a direction compressing the suspension spring 30 is balanced with the force that the movable spring bearing 31 receives in a direction compressing the pressure chamber P from the compressed suspension spring 30 in a state in which a predetermined weight is loaded on the body F of the saddle-ride type vehicle M, and the setting range of the predetermined load mentioned above may be set to be less than the maximum load that can be supported by the elastic force generated when the suspension spring 30 contracts within the stroke range of the shock absorber body D. If the predetermined load is set within this range, the movable spring bearing 31 can be displaced within the stroke range of the shock absorber main body D, making it possible to change the spring constant of the suspension device S. Furthermore, even if the position of the movable partition 38 is not set to maximize the volume of the space within the container 37, if the movable spring bearing 31 is displaced relative to the housing 32 as the suspension spring 30 expands and contracts, it is possible to adjust the degree of contraction of the suspension spring 30 when the spring constant of the suspension device S decreases and the degree of decrease in the spring constant.

[0048] As described above, the suspension device S of this embodiment comprises a suspension spring 30 that supports the vehicle body F of a saddle-ride type vehicle (vehicle) M, a movable spring bearing 31 that supports one end of the suspension spring 30 and is displaceable in the direction in which the suspension spring 30 expands and contracts, a housing 32 that allows movement of the movable spring bearing 31 in the direction in which the suspension spring 30 expands and contracts and forms a pressure chamber P that contains liquid between the movable spring bearing 31 and the housing 32, a stopper 33 that prevents the movable spring bearing 31 from moving further toward the suspension spring when the movable spring bearing 31 moves toward the suspension spring relative to the housing 32 and the pressure chamber P becomes maximum, and an elastic pressure means 34 that is capable of pressurizing the pressure chamber P with an elastic force and that is capable of adjusting the elastic force.

[0049] In the suspension device S configured in this manner, the elastic pressurizing means 34 applies pressure to the pressure chamber P by its elastic force, and one end of the suspension spring 30 is supported by the movable spring bearing 31, so that the movable spring bearing 31 can be fixed immovably in a position restricted by the stopper 33 by adjusting the pressure that the elastic pressurizing means 34 applies to the pressure chamber P, and the movable spring bearing 31 can be displaced relative to the housing 32 according to the degree of contraction of the suspension spring 30. And, because the elastic pressurizing means 34 applies pressure to the pressure chamber P by its elastic force, when the movable spring bearing 31 is displaced relative to the housing 32, the movable spring bearing 31 receives the elastic force of the elastic pressurizing means 34 and functions as a spring together with the suspension spring 30, so that the spring constant of the suspension device S decreases.

[0050] As described above, according to the suspension device S of this embodiment, the spring constant of the suspension device S as a whole can be changed by adjusting the resilient force of the resilient pressure means 34, thereby improving the ride comfort of the vehicle.

[0051] Furthermore, in the suspension device S of this embodiment, the pressure chamber P contains a liquid, and the elastic force of the elastic pressure applying means 34 is transmitted to the movable spring bearing 31 using the liquid as a medium. Therefore, proven seal rings for liquids can be used for the seal rings 31d and 32c that seal the inside of the pressure chamber P, thereby improving practicality.

[0052] Furthermore, the elastic pressurizing means 34 in the suspension S of this embodiment includes a container 37, a movable partition 38 that is movably inserted into the container 37 and defines a space in the container 37 that is connected to the pressure chamber P, and gas and liquid contained in the container 37. According to the suspension S configured in this manner, the elastic pressurizing means 34 functions as an air spring and adjusts the degree of compression of the gas by the displacement of the movable partition 38 within the container 37, thereby adjusting the elastic force acting on the pressure chamber P. Therefore, according to the suspension S of this embodiment, the elastic force can be adjusted by using gas, so the elastic pressurizing means 34 can be made small and lightweight, and its mountability on a vehicle can be improved. Note that the elastic pressurizing means 34 may also be configured such that the air chamber A is eliminated and the space defined in the container 37 by the movable partition 38 is filled with only liquid, and the movable partition 38 is biased by a coil spring or the like to adjust the elastic force of the coil spring or the like, thereby adjusting the pressure acting on the pressure chamber P. The elastic pressurizing means 34 may also be configured to include a metal bellows that stores a liquid whose interior is in communication with the pressure chamber P, a spring or air spring that biases the metal bellows in a direction that compresses it, and an adjustment means that adjusts the elastic force of the spring or air spring. The adjustment means may be, for example, anything that can displace the end of the spring or air spring on the side opposite the metal bellows, and therefore the feed screw mechanism or the like in the elastic pressurizing means 34 described above may be used.

[0053] Furthermore, the elastic pressurizing means 34 of this embodiment is divided into an air chamber A and a liquid chamber B by the elastic partition wall 39, preventing the intrusion of gas into the pressure chamber P. In the suspension device S configured in this manner, the pressure chamber P is pressurized using the elastic force of gas, but the seal rings 31d, 32c that seal the pressure chamber P can be seal rings for liquid, eliminating the need to seal for gas, which is difficult to seal. Thus, the suspension device S of this embodiment makes it possible to use the seal rings 31d, 32c that prevent liquid leakage even when the pressure in the pressure chamber P is increased by using the elastic force of gas, thereby improving practicality. Note that if the gas in the container 37 can be prevented from flowing into the pressure chamber P without using the elastic partition wall 39, the elastic partition wall 39 could be omitted. However, using the elastic partition wall 39 has the advantage of eliminating the risk of gas entering the pressure chamber P.

[0054] Furthermore, when the elastic pressurizing means 34 in the suspension device S of this embodiment has its elastic force minimized, a balance is achieved between the resilient force generated by the suspension spring 30 supporting the vehicle body F when a predetermined weight is loaded and the biasing force that biases the suspension spring 30 while the movement of the movable spring bearing 31 is restricted by the stopper 33. According to the suspension device S configured in this manner, when a predetermined weight is loaded on the vehicle body F of the saddle-ride type vehicle (vehicle) M when the elastic pressurizing means 34 has its elastic force minimized, the movable spring bearing 31 also displaces toward inside the housing 32 when the suspension spring 30 contracts, so that the spring constant of the suspension device S can be made smaller than the spring constant of the suspension spring 30. Note that if the predetermined weight is set to about the weight of one passenger, the spring constant of the suspension device S installed on the saddle-ride type vehicle M while the vehicle is running can be made smaller than the spring constant of the suspension spring 30, thereby achieving a ride comfort preferred by the passenger of the saddle-ride type vehicle M.

[0055] Moreover, the rear cushion unit RCU of this embodiment includes an outer shell 4, a shock absorber main body D having a rod 2 inserted into the outer shell 4 so as to be axially movable and capable of generating a damping force that suppresses relative movement between the outer shell 4 and the rod 2, a suspension device S, and a fixed spring bearing 25 that is provided on the rod 2 and supports the other end of a suspension spring 30, with the housing 32 and the movable spring bearing 31 being provided on the outer shell 4. In the rear cushion unit RCU configured in this manner, since it includes the suspension device S, the spring constant of the suspension device S can be changed, thereby improving the ride comfort of the vehicle, and the suspension device S can be integrated with the shock absorber main body D and interposed between the body F and rear wheel W of a saddle-ride type vehicle (vehicle) M, making it easy to mount the suspension device S on the saddle-ride type vehicle (vehicle) M.

[0056] Furthermore, the rear cushion unit RCU of this embodiment is equipped with an annular bump cushion 21 attached to the outer periphery of the end of the rod 2 opposite the outer shell, and a bump stopper 22 attached to the outer shell 4 and axially facing the bump cushion 21, and the housing 32 does not restrict movement of the movable spring bearing 31 toward the opposite suspension spring side until the shock absorber body D contracts and the bump cushion 21 and bump stopper 22 abut against each other. With the rear cushion unit RCU of this embodiment configured as described above, even if the shock absorber main body D contracts when the spring constant of the suspension device S is reduced and the bump cushion 21 comes into contact with the bump stopper 22, the stroke length of the movable spring bearing 31 in the direction of contracting the pressure chamber P relative to the housing 32 is sufficiently ensured, and the movable spring bearing 31 and the housing 32 do not collide until the bump cushion 21 comes into contact with the bump stopper 22, so the spring constant does not suddenly increase, causing a rough and uncomfortable ride for the occupant of the saddle-ride type vehicle (vehicle) M.

[0057] The shapes and structures of the movable spring bearing 31 and the housing 32 are merely examples and can be modified as appropriate. For example, when the suspension device S is applied to the shock absorber main body D, the housing 32 may be attached to the outer periphery of the outer shell 4, and the movable spring bearing 31 may be brought into sliding contact with the outer periphery of the outer shell 4 in addition to the housing 32.

[0058] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims.

[0059] 2... Rod, 4... Outer shell, 21... Bump cushion, 22... Bump stopper, 25... Fixed spring bearing, 30... Suspension spring, 31... Movable spring bearing, 32... Housing, 33... Stopper, 34... Elastic pressure means, 37... Container, 38... Movable partition, D... Shock absorber body, F... Vehicle body, M... Saddle-ride type vehicle (vehicle), P... Pressure chamber, RCU... Rear cushion unit, S... Suspension device, W... Rear wheel

Claims

1. A suspension device comprising: a suspension spring that supports a vehicle body; a movable spring bearing that supports one end of the suspension spring and is displaceable in the direction in which the suspension spring expands and contracts; a housing that allows movement of the movable spring bearing in the direction in which the suspension spring expands and contracts and forms a pressure chamber for containing liquid between the movable spring bearing and the housing; a stopper that prevents the movable spring bearing from moving further toward the suspension spring when the movable spring bearing moves toward the suspension spring relative to the housing and the pressure chamber becomes maximum; and elastic pressurizing means that is capable of pressurizing the pressure chamber with an elastic force and that is capable of adjusting the elastic force.

2. A suspension device according to claim 1, wherein said elastic pressurizing means comprises: a container; a movable partition wall which is movably inserted into said container and defines a space within said container which communicates with said pressure chamber; and a gas and a liquid contained within said container.

3. A suspension device as claimed in claim 1, wherein, when said elastic pressure means is in a state where said elastic force is minimized, a state of balance is achieved between the resilient force generated by said suspension spring which supports said vehicle body when a predetermined weight is loaded and the biasing force which biases said suspension spring while the movement of said movable spring bearing is restricted by said stopper.

4. A rear cushion unit comprising: a shock absorber body having an outer shell and a rod axially inserted into the outer shell and capable of generating a damping force that suppresses relative movement between the outer shell and the rod; a suspension device described in any one of claims 1 to 3; and a fixed spring bearing provided on the rod and supporting the other end of the suspension spring, wherein the housing and the movable spring bearing are attached to the outer shell.

5. A rear cushion unit as claimed in claim 4, comprising: an annular bump cushion attached to the outer periphery of the end of the rod opposite the outer shell; and a bump stopper attached to the outer shell and axially facing the bump cushion, wherein the housing does not restrict movement of the movable spring bearing towards the opposite suspension spring until the shock absorber body contracts and the bump cushion comes into contact with the bump stopper.

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