JPH085420B2 - Hydraulic shock absorber for rear wheel suspension of motorcycles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic shock absorber that variably controls a damping force according to a displacement amount of a wheel with respect to a vehicle body.

(Prior art and its problems) Generally, a hydraulic shock absorber provided in a motorcycle or the like generates a damping force according to the contraction speed of a damper, but when cornering or when the weight of a vehicle body is large. In addition, the amount of wheel displacement (the amount of contraction of the damper) is improved in order to improve the grounding property of the wheel, or to effectively absorb and mitigate this when the wheel receives a large impact and prevent the piston from bottoming. It is desirable that the damping force be increased accordingly.

Conventionally, as this type of hydraulic shock absorber, for example, JP-A-55-
The device disclosed in Japanese Patent No. 15372 is equipped with a variable damping mechanism in a tank that stores excess hydraulic oil corresponding to piston rod intrusion volume in a damper, and this variable damping mechanism is applied to excess hydraulic oil flowing into the tank. It adjusts the resistance of the free piston, which is linked to the free piston that defines the gas chamber in the tank. Since this free piston is displaced along with the inflow of excess hydraulic oil, the damping force can be automatically increased according to the amount of contraction of the damper.

However, since the position of the free piston in the tank changes depending on the temperature of the gas chamber, there is a problem that the damping force characteristics differ depending on the temperature condition of the tank.
Further, since the valve mechanism is provided inside the tank, it is difficult to adjust the damping force characteristic from the outside.

Further, the present applicant has already proposed a device for automatically increasing the damping force according to the internal pressure of the tank, but it cannot be denied that the damping force characteristics are affected by the temperature condition of the tank ( JP-A-57-76338, JP-A-57-116
See Japanese Patent No. 946).

 An object of the present invention is to solve the above problems.

(Means for Solving Problems) According to the present invention, a damper is connected between a vehicle body and an unsprung member that interlocks with the displacement of a wheel, and excess hydraulic oil equivalent to the intrusion volume of the piston rod of the damper is provided. In a hydraulic shock absorber having a gas-filled tank for storing, a tank is rotatably connected to one of the vehicle body and an unsprung member, and a damping mechanism for imparting resistance to the flow of the excess hydraulic oil in the tank. Is provided, and a detection rod that detects the relative displacement between the vehicle body and the unsprung member is slidably protruded from the tank in conjunction with the damping mechanism, and the damping mechanism changes the damping force based on the displacement of the detection rod. It is configured as a variable damping mechanism, and this detection rod is rotatably connected to either the unsprung member or the other body.

(Operation) In this way, by connecting the detection rod protruding from the tank to the unsprung member substantially parallel to the damper, the variable damping mechanism directly detects the displacement of the wheel via the detection rod, and The damping force can be controlled stably without depending on the temperature, only by the displacement of the wheel, and if the adjusting mechanism that can adjust the length of the protruding portion of the detection rod from the outside is provided, the damping force characteristics can be improved. Can be easily changed.

(Example) Hereinafter, an example of the present invention is described based on an accompanying drawing.

As shown in FIG. 1, a damper is provided between a motorcycle body 31 and a swing arm (unsprung member) 33 that supports a rear wheel 32.
Connect 34.

The tank 35 for storing the excess hydraulic oil in the damper 34 is formed separately from the damper 34, and communicates with the damper 34 via a hose 37.

While one end of the tank 35 is pivotally attached to the vehicle body 31 via a pin 38, the detection rod 14 that slidably projects from the tank 35.
Is pivotally attached to the swing arm 33 via a pin 39.

As shown in FIG. 2, the tank 35 has a free piston 2 slidably accommodated in a bottomed cylindrical tank body 1,
A gas chamber A for enclosing the high-pressure gas therein and an oil reservoir chamber B for accumulating excess hydraulic oil from the damper 34 are defined.

An end cap 8 is attached to the open end of the tank body 1 via an O-ring 26 and a snap ring 9, and the hose 37 is connected to the end cap 8 via a connector 28.

An oil seal case 20 is screwed into the end cap 8, and is fixed by tightening it via a lock nut 23. The detection rod 14 is slidably penetrated through the end cap 8 via an oil seal 21.

An annular gap G communicating with the damper 34 via a hose 37 between the outer peripheral surface of the detection rod 14 and the inner peripheral surface of the end cap 8.
Define.

An annular valve seat 10 is fixed to the inside of the end cap 8 via a retaining ring 13, and a check valve 11 which is seated on the valve seat 10 via a leaf spring 12 is arranged. The check valve 11 is opened for hydraulic oil returning from the oil reservoir B to the damper 34.

Two tapered grooves 15a extending in the axial direction are formed on the outer peripheral surface of the tip portion of the detection rod 14, and the annular gap G and the oil reservoir B are communicated between the tapered groove 15a and the inner peripheral surface of the valve seat 10. A variable orifice F is constructed.

The taper groove 15a has one end formed in a taper shape, and an area of the variable orifice F opened between the detection rod 14 and the inner peripheral surface of the valve seat 10 as the detection rod 14 enters the tank 35 is reduced. The damping force applied to the surplus hydraulic oil flowing into the oil reservoir B is gradually reduced so that the damping force can be increased.

An annular valve seat 16 is fixed inside the end cap 8 via a ring screw 17, and a relief valve 18 is seated on the valve seat 10 via a relief spring 19.
To arrange. One end of the relief spring 19 is supported by the oil seal case 20.

An annular gap C is defined between the relief valve 18 and the oil seal case 20, and the detection rod 14 has a through hole 15b penetrating laterally and a through hole axially penetrating through the through hole 15b. Form 15e. As a result, when the relief valve 18 opens, the excess hydraulic oil from the damper 34 flows into the oil reservoir B from the annular gap G through the annular gap C and the through holes 15b and 15c. That is, the relief valve 18 has the tapered groove 15a.
A predetermined damping force is applied to the surplus hydraulic oil that bypasses and flows into the oil reservoir B.

The bracket 6 pivotally supporting the pin 39 is screwed to the base end of the detection rod 14, and is fixed by tightening it through a lock nut 25. By changing the screwing position of the bracket 6, the initial position of the detection rod 14 with respect to the valve seat 10 can be adjusted.

The protrusion of the detection rod 14 and the lock nut 25 are covered with a bellows-shaped die cover 24.

A bracket 6 for pivotally supporting the pin 38 is integrally formed at one end of the tank body 1. Reference numeral 4 in the drawing denotes a gas filling valve.

It is configured in this way, and the operation will be described next.

For example, when the rear wheel 32 rides on a road surface protrusion or the like, as the damper 34 contracts, excess hydraulic oil corresponding to the intrusion volume of the piston rod (not shown) from the damper 34 is stored in the tank via the hose 37. Guided to 35. This hose
The excess hydraulic fluid guided by 37 flows into the annular gap G through the connector 28, then flows from the annular gap G into the oil reservoir chamber B through the tapered groove 15a, and the pressure in the annular gap G exceeds the set value. Then, the relief valve 18 opens against the relief spring 19, and the annular clearance C and the through hole 15
It flows into the oil reservoir B through b and 15c.

On the other hand, since the detection rod 14 is attached to the swing arm 33 substantially parallel to the damper 34, the detection rod 14 enters the tank body 1 in proportion to the contraction amount (stroke amount) of the damper 34. As a result, the taper groove 15a formed in the detection rod 14 is formed within the predetermined range of the average stroke of the damper 34.
The opening area of the valve seat 10 is reduced by the inner peripheral surface of the valve seat 10 to increase the resistance imparted to the excess hydraulic oil passing through the tapered groove 15a (variable orifice F), and shuts off this flow near the maximum stroke.

As a result, Fig. 3 shows that the contraction speed of the damper 34 is V ₁ , V ₂ ,
Although the damping force characteristics are shown according to the stroke amount of the damper 34 under a constant condition of V ₃ respectively, the compression side damping force is set to the stroke amount of the damper 34 in the predetermined range of the stroke amount of SR to R. Can be increased accordingly.

In this way, by transmitting the displacement (stroke) of the rear wheel 32 to the variable orifice F via the link mechanism including the swing arm 33 and the detection rod 14, the damping force control is influenced by the temperature condition of the tank 35. It can be performed stably without

By loosening the lock nut 25 and adjusting the screwing position of the detection rod 14 with respect to the bracket 6, the point S at which the damping force starts increasing in FIG. 3 can be easily changed.

Also, loosen the lock nut 23 to remove the oil seal case.
By adjusting the screwing position of 20 with respect to the end cap 8, the valve opening pressure of the relief valve 18 changes, and the R point (the valve opening pressure of the relief valve 18) where the damping force ends in FIG. 3 is easily changed. it can.

On the other hand, when the damper 34 is extended, the hydraulic oil in the oil reservoir B opens the check valve 11 and causes almost no resistance to the annular gap G.
Although it flows out to the damper 34 via the hose 37, if the tapered groove 15a is released from the shielding by the valve seat 10, the hydraulic oil in the oil reservoir B also flows into the annular gap G from the tapered groove 15a.

 Next, another embodiment shown in FIG. 4 will be described.

Two taper grooves 15a are formed on the outer peripheral surface of the detection rod 14, and a through hole 15b for communicating the taper groove 15a with the oil reservoir B is formed.
And form 15c.

The valve seat 10 is press-fitted and fixed to the end cap 8, and the inner peripheral surface thereof opens and closes the tapered groove 15a.

A check valve 11 biased by a leaf spring 12 is arranged on the valve seat 10 via a retaining ring 42, and a relief valve 18 facing the check valve 11 for seating the check valve 11 is arranged. While the relief valve 18 is locked to the valve seat 10, one end of a relief spring 19 that biases the relief valve 18 is supported by a retaining ring 44 via a retainer 43.

In this case, since the check valve 11 and the relief valve 18 are in contact with each other, the communication between the oil reservoir chamber B and the annular gap C can be cut off, so that the valve seats on which they are seated are eliminated and the valve devices can be made compact. It is possible.

 Next, another embodiment shown in FIG. 5 will be described.

The detection rod 14 has a through hole 15b penetrating in the lateral direction and a shaft hole 51 connected to the penetrating hole 15b and penetrating in the axial direction. In the middle of the shaft hole 41, a seat portion 52 that expands in a stepwise manner is formed, and a ball-shaped relief valve 53 seated on the seat portion 52 and a relief spring 54 that urges the relief valve 53 are arranged. Set up. One end of the relief spring 54 is supported by a ring screw 54 screwed into the shaft hole 51.

The taper groove 15a formed in the detection rod 14 is opened and closed by the inner peripheral surface of the valve seat 10, and the check valve 11 seated on the valve seat 10 is arranged.

Also in this case, the valve device can be made compact by mounting the relief valve 53 in the detection rod 14.

As described above, according to the present invention, the tank separated from the damper is rotatably connected to one of the vehicle body side and the unsprung member and slidably protrudes from the tank to control the damping force. Since the detection rod is rotatably connected to either the unsprung member or the other side of the vehicle body so as to be driven, the wheel displacement can be detected directly and accurately without being affected by temperature conditions such as the tank. Thus, it is possible to accurately and stably control the predetermined damping force according to the displacement amount over the entire stroke of the displacement of the wheel.

Further, according to the present invention, the length of the detection rod can be configured to be adjusted from the outside, the setting of the valve displacement that constitutes the damping mechanism, the setting pressure of the relief valve, and the like can be changed on the vehicle body. Since it is possible with the tank attached, the damping force characteristics can be easily changed.

Further, since the tank is separated, the structure of the variable damping force mechanism portion can be simplified and the weight and size can be reduced.

Further, since the tank and the detection rod are rotatable with respect to the vehicle body or the unsprung member, even if the vehicle body and the unsprung member are displaced relative to each other, the tank and the detection rod are not twisted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an embodiment of the present invention, FIG. 2 is a sectional view of the same tank, and FIG. 3 is a graph showing damping force characteristics. FIG. 4 is a sectional view showing another embodiment. FIG. 5 is a sectional view showing still another embodiment. 1 ... Tank body, 6 ... Bracket, 14 ... Detection rod, 15
a: taper groove, 31 ... vehicle body, 32 ... rear wheel, 33 ... swing arm, 34 ... damper, 35 ... tank, A ... gas chamber, B ... oil reservoir, F ... variable orifice

Claims (1)

[Claims] 1. A hydraulic buffer provided with a gas filled tank for connecting a damper between a vehicle body and an unsprung member which is interlocked with displacement of a wheel, and storing a surplus hydraulic oil corresponding to an intrusion volume of a piston rod of the damper. In the device, a tank is rotatably connected to one of the vehicle body and the unsprung member, and a damping mechanism for imparting resistance to the flow of the excess hydraulic oil is provided in the tank, and the tank is interlocked with the damping mechanism. A detection rod for detecting relative displacement between the vehicle body and the unsprung member is slidably projected from the tank, and the damping mechanism is configured as a variable damping mechanism in which the damping force changes based on the displacement of the detection rod. A hydraulic shock absorber for rear-wheel suspension of a two-wheeled vehicle, wherein a detection rod is rotatably connected to the other one of the unsprung member and the vehicle body.