JP3341244B2 - Hydraulic shock absorber with reservoir tank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber used as a shock absorber for a motorcycle rear suspension or the like, and more particularly, to a hydraulic shock absorber having a reservoir tank provided separately from a cylinder case made of a monotube. About.

[0002]

2. Description of the Related Art As one of hydraulic shock absorbers used as a shock absorber in a rear suspension of a motorcycle, a monotube is used to compensate for oil amount fluctuations inside a cylinder due to a change in volume of a piston rod or a change in temperature. The inside of a cylinder case made of is connected to a reservoir tank provided separately from the cylinder case, and a hydraulic buffer with a reservoir tank that allows oil equivalent to the oil amount fluctuation in the cylinder case to enter and exit the reservoir tank Containers have been generally known from the past.

[0003] Such a hydraulic shock absorber with a reservoir tank has a smaller overall cylinder case diameter than a double cylinder type hydraulic shock absorber in which a reservoir chamber is formed between an inner tube (cylinder case) and an outer tube. The amount of oil in the cylinder case can be increased, and the oil in the cylinder case can be released to the reservoir tank for cooling. This is effective for preventing so-called heat sag caused by a change in oil viscosity.

[0004]

In the conventional hydraulic shock absorber with a reservoir tank as described above, when the diameter of the cylinder case is reduced, the piston itself becomes smaller, and the damping force formed by the throttle portion and the one-way valve is provided there. Since the degree of freedom for forming the generating mechanism is reduced, if the damping force generating mechanism for both the extension stroke and the compression stroke is to be formed near the piston, the structure of the piston becomes complicated, and both the extension stroke and the compression stroke become complicated. It becomes difficult to set the damping force as desired.

[0005] In view of this, a double-cylinder type hydraulic shock absorber is usually press-fitted and fixed to an end of a piston case on a side communicating with a reservoir tank by using a base valve usually installed at the bottom of the inner tube. It is conceivable to disperse the damping force generation in the extension stroke and the compression stroke in the damping force generation mechanism formed in the vicinity and the damping force generation mechanism formed in the base valve, and to set the damping force respectively. In such a case, it is necessary to perform a troublesome operation of press-fitting and assembling the base valve into the piston case and then connecting the reservoir tank and the piston case.

An object of the present invention is to solve the above-mentioned disadvantages of the conventional hydraulic shock absorber with a reservoir tank. More specifically, the present invention disperses the damping force generating mechanism for the extension stroke and the compression stroke. It is an object of the present invention to provide a hydraulic shock absorber with a reservoir tank that can simplify the structure near the piston and can easily assemble a damping force generating mechanism formed in a portion other than the vicinity of the piston. I have.

[0007]

According to the present invention, in order to solve the above-mentioned problems and to achieve the object, a sliding of a piston in a cylinder case made of a monotube as described in claim 1 is provided. According to the reciprocation of the piston rod
In a hydraulic shock absorber in which oil in the cylinder case enters and exits a reservoir tank provided separately from the cylinder case, the reservoir tank is detachably connected to a boss portion fixed to an upper end of the cylinder case, One of the damping force generation mechanism in the extension stroke and the damping force generation mechanism in the compression stroke is formed near the piston, and the other is assembled to the connection between the boss and the reservoir tank. .

In the hydraulic shock absorber with a reservoir tank according to the first aspect of the present invention, as in the second aspect, the reservoir tank is integrally formed with the vehicle body mounting portion of the hydraulic shock absorber. The mounting part and the boss part are screwed together, so that the boss part and the reservoir tank are detachably connected, and that the damping force generating mechanism is sandwiched and assembled between the boss part and the vehicle body mounting part. It is a feature.

Further, in the hydraulic shock absorber with reservoir tank according to claim 1 or 2, the damping force generating mechanism assembled to the connection portion between the boss portion and the reservoir tank as described in claim 3 above. , A plate valve and a leaf spring.

[0010]

[Operation] With the above configuration, only the damping force generating mechanism for either the extension stroke or the compression stroke is formed near the piston, so that the structure of the piston is simplified. Since the damping force generating mechanism for the other stroke is assembled to the connection portion between the boss portion and the reservoir tank that are detachably connected, the mounting operation and the replacement are easily performed.

According to the second aspect of the present invention, the operation of attaching the reservoir tank to the cylinder case and the operation of assembling the damping force generating mechanism between the boss portion and the reservoir tank are performed by the hydraulic shock absorber main body. Is completed at the same time in the process of assembling work of screwing the vehicle body mounting portion to the vehicle.

Further, according to the third aspect of the present invention, the damping force generating mechanism disposed between the boss portion and the reservoir tank can be easily formed by simply overlapping the simple members such as the plate valve and the leaf spring. Formed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic shock absorber with a reservoir tank according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a cushion unit for a rear suspension of a motorcycle in which a hydraulic shock absorber with a reservoir tank of the present invention is used as a shock absorber. The cushion unit 1 is a hydraulic shock absorber (shock absorber) body. 2, a reservoir tank 3 and a coil spring 4 are provided as main parts. At the upper end thereof, a mounting part 5 to the vehicle body is provided, and at the lower end, a mounting part 6 to the swing arm is provided, as shown in FIG. like,
It is installed between the rear frame (seat frame) 7 of the vehicle body and the swing arm 8.

FIG. 2 shows a state in which the cushion unit 1 using the hydraulic shock absorber of the present embodiment is mounted on a scooter type motorcycle.
Is composed of a power system unit including an engine and a transmission.

Hydraulic shock absorber main body 2 of cushion unit 1
The piston rod 12 is penetrated from the lower end of the cylinder case 11 made of a monotube so as to be able to freely enter and exit the cylinder case 11, and the lock nut 13 and the swing arm mounting portion 6 are screwed to the lower end of the piston rod 12. A stopper 14 is provided above the lock nut 13, and a piston 15 is formed at an upper end of the piston rod 12.

As shown in FIG. 6, the piston 15 divides the interior of the cylinder case 11 into an upper oil chamber 11a and a lower oil chamber 11b and slides up and down. A directional valve 15b is formed, and a piston rod 12 near the piston 15 has a piston 1
The upper oil chamber 11a and the lower oil chamber 11b partitioned by 5
Is formed, and a one-way valve 1 is formed.
5B is a cylinder case 11 as shown in FIG.
The lower end opening of the oil passage hole 15a is formed so as to open when the piston 15 rises inside and close as the piston 15 descends as shown in FIG. 6B.

A bearing portion 16 and a seal portion 17 are provided in the cylinder case 11 at a portion through which the piston rod 12 at the lower end thereof penetrates so that the piston rod 12 can be slidably held in a sealed state. A steel boss 18 is integrally fixed to the upper end of the boss 18 by resistance welding or the like, as shown in FIG.
A thread 18a is formed on the upper outer peripheral surface, a flange 18b is formed on the lower outer periphery, and an oil passage portion 18c is vertically penetrated through its axis.

The boss 18 fixed to the upper end of the cylinder case 11 has a threaded portion 18 formed on the outer peripheral surface of the upper portion.
a, the vehicle body mounting portion 5 is detachably screwed,
The tank body 31 of the reservoir tank 3 is formed integrally with the vehicle body mounting portion 5 via a connecting portion 32 at a position obliquely below the vehicle body mounting portion 5.

The coil spring 4 is used for the cylinder case 1
A spring seat 19 which is retained upward by a flange 18b of a boss portion 18 fixed to the upper end of the spring 1 and a spring which is retained downward by a swing arm mounting portion 6 screwed to a lower end of the piston rod 12. The cylinder case 1 of the hydraulic shock absorber main body 2 is guided by the guide 20.
1 and the outside of the piston rod 12 are installed.

The reservoir tank 3 is formed by integrally forming a tank body 31 having an open bottom with a connecting portion 32 as a monoblock made of an aluminum die-cast with the vehicle body mounting portion 5. An oil passage 33, which is openably and closably closed to the outside by the screw plug 21, is formed in the reservoir tank 3 so as to communicate with the oil passage portion 18 c of the boss portion 18 and the inside of the reservoir tank 3.

In the tank body 31 of the reservoir tank 3, a flexible film body 34 having a cross section bulging upward in an inverted U-shape, and a closed space 3b is formed between the film body 34 and the flexible film body 34. Is inserted from the open bottom of the tank main body 31 and the housing cap 35 is fixed to the tank main body 31 with the circlip 36 to communicate with the inside of the cylinder case 11 above the membrane 34. Each of the oil chambers 3a is formed with a gas chamber 3b below the film body 34, which is filled with a gas such as N ₂ gas.

The housing cap 35 has a gas chamber 3b.
A hole 35a for filling N ₂ gas or the like is opened therein, and the hole 35a is closed by a rubber valve 37 so that gas can be filled and the gas chamber is sealed after gas filling. An overcap 38 for covering the housing cap 35 and the circlip 36 from outside is attached to the bottom of the tank body 31 after gas filling.

In this embodiment, the reservoir tank 3
The inside is partitioned into an oil chamber 3a and a gas chamber 3b by a flexible film 34. As means for partitioning the inside of the reservoir tank 3, not only the flexible film 34 but also, for example, As shown in FIG. 7, this is also possible by using a free piston 40.

FIG. 7 shows an example in which the interior of the reservoir tank 3 is divided into an oil chamber 3a and a gas chamber 3b by a free piston 40. A housing cap 42 is integrated with a lower end of a cylindrical inner tube 41 by resistance welding or the like. The free piston 40 is slidably mounted in the cylinder of the inner tube 41 and assembled as an integral unit, and this unit is inserted into the tank body 31 from the opened bottom. By inserting and fixing the housing cap 42 to the tank main body 31 with the circlip 36, the inside of the reservoir tank 3 is partitioned so that the upper part of the free piston becomes the oil chamber 3a and the lower part becomes the gas chamber 3b.

In this case, the housing cap 42 has a certain thickness and does not need to be protected by an overcap from the outside. A hole 42a for filling the gas chamber 3b with gas is opened. The hole 42 a is closed by a rivet 43 from the outside after gas filling, instead of being closed by a rubber valve 37 and providing an overcap.

The tubular inner tube 41 as described above
According to the structure in which the free piston 40 is mounted through the inner space, the inner diameter of the tank body does not need to be precisely machined to match the free piston as in a conventional free piston type reservoir tank. The number of processing steps can be minimized.

By the way, in the hydraulic shock absorber of the present embodiment having the above-described structure, the damping force generating mechanism in the elongating step includes an oil passage hole 15a formed in the piston 15 as shown in FIG. While formed by a one-way valve 15b and a throttle portion 12a formed on the piston rod 12, a damping force generating mechanism in a compression step is provided with a boss portion 18 fixed to the upper end of a cylinder case, a vehicle body mounting portion 5, Is formed at the connection part 23 of the first embodiment.

That is, as shown in FIG. 3, the boss 18 fixed to the upper end of the cylinder case 11 and the connecting portion 32
The vehicle body mounting portion 5 formed integrally with the reservoir tank 3 via a threaded portion 18a is detachably screwed with a screw portion 18a, so that the oil passage portion 18c of the boss portion 18 and the oil communicating with the reservoir tank 3 are formed. Opening 33a of passage 33
Are connected, and at a connection portion of the oil passage,
A gap 23 is formed between the lower surface 5a of the vehicle body mounting portion around the opening 33a and the upper end of the boss portion 18 so that the plate valve 24 and the leaf spring 25 can move up and down within the gap 23. It is sandwiched and assembled between the mounting portion 5 and the boss portion 18.

As shown in FIG. 4A, the plate valve 24 is a disk having a throttle portion 24a opened in the center and a plurality of oil passage holes 24b opened in the peripheral portion. The leaf spring 25 is a ring-shaped disc spring having the same outer diameter as the plate valve 24, as shown in FIG. 18 and the upper end.

As described above, the damping force generating mechanism for the extension stroke is formed near the piston 15, and the damping force for the compression stroke is generated at the connecting portion 23 between the vehicle body mounting portion 5 and the boss portion 18 integrated with the reservoir tank 3. The operating state of the hydraulic shock absorber according to the present embodiment to which the mechanism is attached will be described below.

In the compression stroke of the hydraulic shock absorber, as the piston 15 rises in the cylinder case 11, the cylinder 15 discharges oil corresponding to the volume of the piston rod 12 entering the cylinder case 11. The oil in the case 11 flows into the reservoir tank 3 through the oil passage 18c of the boss portion and the oil passage 33.

At this time, as shown in FIG. 6 (A), the oil in the upper oil chamber 11a flows into the lower oil chamber 11b as the piston 15 rises. 15b is opened, a part of the oil in the upper oil chamber 11a passes through the throttle part 12a of the piston rod 12, and a large part of the oil passes through the oil passage hole 1 of the piston 15.
5a, and flows into the lower oil chamber 11b without receiving a large resistance.

At the same time, the oil discharged from the cylinder case 11 and flowing into the reservoir tank 3 through the oil passage 33 from the oil passage portion 18c of the boss portion 18, as shown in FIG. The plate valve 24 is pressed against the lower surface 5a of the vehicle body mounting portion by the flow pressure of the oil flowing from the oil passage portion 18c to the oil passage 33, and the oil passage hole 24b opened in the periphery of the plate valve 24 is formed by the lower surface 5a of the vehicle body mounting portion. Since the oil is closed, all of the oil passes through the throttle portion 24a, and the hydraulic shock absorber obtains a damping effect by the throttle portion 24a.

On the other hand, in the extension stroke of the hydraulic shock absorber, oil corresponding to the volume of the piston rod 12 that comes out of the cylinder case 11 as the piston 15 descends in the cylinder case 11 is compensated. Therefore, the oil in the reservoir tank 3 flows into the cylinder case 11 through the oil passage 33 and the oil passage 18c of the boss.

At this time, as shown in FIG. 5 (B), the oil in the reservoir tank 3 passes through the opening 33a from the oil passage 33, and a part thereof flows into the throttle portion 24 of the plate valve 24.
a through the oil passage hole 24b from the gap between the lower surface 5a of the vehicle body mounting portion and the plate valve 24, and from the oil passage portion 18c of the boss portion 18 into the cylinder case 11 without receiving a large resistance. Flow in.

At the same time, in the cylinder case 11, as shown in FIG. 6B, the oil in the lower oil chamber 11b flows into the upper oil chamber 11a as the piston 15 descends. Since the one-way valve 15b is closed, the oil in the lower oil chamber 11b
And flows into the upper oil chamber 11a only through the narrowed portion 12a, so that the hydraulic shock absorber obtains the damping effect by the narrowed portion 12a.

According to the hydraulic shock absorber with a reservoir tank of the present embodiment as described above, the piston 15 is provided near the piston 15 as a damping force generating mechanism in the extension stroke.
Since only the oil passage hole 15a and the one-way valve 15b are provided and the throttle rod 12 is provided with the throttle portion 12a, the structure of the piston 15 can be extremely simplified.

As the damping force generating mechanism in the compression stroke, the plate valve 24 and the leaf spring 25 are simply sandwiched between the connecting portion 23 of the boss portion 18 and the vehicle body mounting portion 5, so that the damping force generating mechanism is a simple member. Can be formed,
The work of attaching to or replacing the hydraulic shock absorber can also be easily performed.

Further, by appropriately replacing the leaf spring 25 and adjusting the gap between the lower surface 5a of the vehicle body mounting portion and the plate valve 24 during the extension process, the oil resistance at the relevant portion is changed, and the hydraulic buffer in the extension process is adjusted. The damping effect obtained from the entire vessel can be finely adjusted.

Furthermore, since the reservoir tank 3 and the vehicle body mounting portion 5 are integrated, in the process of assembling the vehicle body mounting portion 5 into the hydraulic shock absorber main body 2 by screwing,
The work of attaching the reservoir tank 3 to the cylinder case 11 and the work of assembling the damping force generating mechanism installed between the boss 18 and the reservoir tank 3 can be completed at the same time, and the work of assembling the entire hydraulic shock absorber can be completed. It is greatly simplified.

Although the embodiment of the hydraulic shock absorber with a reservoir tank according to the present invention has been described above, the present invention is not limited to the specific structure as described above. The opening / closing direction of the one-way valve in the mechanism can be reversed from that of the embodiment, and the positions of the damping force generation mechanism during the extension stroke and the damping force generation mechanism during the compression stroke can be reversed from the embodiment. Needless to say, the design can be appropriately changed.

[0043]

According to the hydraulic shock absorber with a reservoir tank of the present invention as described above, only the damping force generating mechanism for either the extension stroke or the compression stroke is formed near the piston. The structure in the vicinity can be simplified, and the other damping force generating mechanism formed in the part other than the vicinity of the piston can also simplify the structure itself, and the assembling work is also easy. Becomes

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view showing one embodiment of a hydraulic shock absorber with a reservoir tank of the present invention.

FIG. 2 is a side view showing a state where the hydraulic shock absorber shown in FIG. 1 is attached to a vehicle body.

FIG. 3 is a partially enlarged sectional view of the hydraulic shock absorber shown in FIG. 1;

FIG. 4 is a front view of (A) a plate valve used to form a throttle portion and a one-way valve for generating a damping force in a compression process in the embodiment shown in FIG. 1, and (B). Sectional drawing of a plate valve and a leaf spring.

FIG. 5 is a partially enlarged sectional view showing (A) a state during a compression stroke and (B) a state during an extension stroke in a connection portion between the boss portion and the reservoir tank in the embodiment shown in FIG. 1;

FIG. 6 is a partially enlarged sectional view showing (A) a state during a compression stroke and (B) a state during an expansion stroke near the piston of the embodiment shown in FIG. 1;

FIG. 7 is a partial cross-sectional side view showing another example of the structure of the reservoir tank itself.

[Explanation of symbols]

 2 Hydraulic shock absorber main body 3 Reservoir tank 5 Body mounting portion 11 Cylinder case 12 Piston rod 12a Restricted portion near piston (damping force generating mechanism) 15 Piston 15a Piston oil passage hole (damping force generating mechanism) 15b One-way valve (damping) 18 Boss 23 Connection between boss and reservoir tank 24 Plate valve (damping force generating mechanism) 25 Leaf spring (damping force generating mechanism)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model 1-102538 (JP, U) Japanese Utility Model 1-1131044 (JP, U) Japanese Utility Model 2-11246 (JP, U) Japanese Utility Model 2 40135 (JP, U) Fully open sho 64-17047 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16F 9/00-9/58 B62K 25/00-27/16

Claims (3)

(57) [Claims] 1. A hydraulic buffer in which oil in a cylinder case flows into and out of a reservoir tank provided separately from the cylinder case in accordance with the reciprocation of a piston rod caused by sliding of a piston in a cylinder case formed of a monotube. In the container, a reservoir tank is detachably connected to a boss portion fixed to an upper end of a cylinder case, and one of a damping force generation mechanism in an extension stroke and a damping force generation mechanism in a compression stroke is near a piston. A hydraulic shock absorber with a reservoir tank, characterized in that the hydraulic shock absorber with the other end is attached to a connection between the boss portion and the reservoir tank. 2. A reservoir tank is formed integrally with a vehicle body mounting portion of the hydraulic shock absorber, and the boss portion and the reservoir tank are detachably connected by screwing the vehicle body mounting portion and the boss portion, The hydraulic shock absorber with a reservoir tank according to claim 1, wherein a damping force generating mechanism is sandwiched and assembled between the boss portion and the vehicle body mounting portion. 3. The hydraulic pressure with a reservoir tank according to claim 1, wherein the damping force generating mechanism attached to the connection between the boss portion and the reservoir tank is formed by a plate valve and a leaf spring. Shock absorber.