JPH09287628A - Piston valve for shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a feeling of ride on a vehicle in a region where the moving speed of a piston rod is a middle low speed and to prevent the decrease of running stability. SOLUTION: Individually from a flow passage consisting of the orifice 16 of a disc sheet 5, an internal flow passage 10 having a ball 14 energized through the force of a spring 13 is formed in a piston rod 2. In a middle low region, oil is caused to flow through the internal flow passage 10 in addition to the orifice 16 and a damping force in the middle low region is reduced to improve a feeling of ride on a vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber piston valve having an improved riding sensation without deteriorating the handling characteristics, and particularly, the riding sensation in a choppy ride is greatly improved. The present invention relates to a shock absorber piston valve.

[0002]

2. Description of the Related Art A shock absorber is a connecting member that is provided between a body portion of a vehicle body and a tire together with a coil spring of a suspension device, and temporarily absorbs vibration transmitted from the tire to a passenger of a vehicle. It makes you feel a soft ride. Also, when driving on a road surface under conditions such as a curve or a steep rugged road, the tire greatly vibrates and the ground contact with the road surface is deteriorated, but the shock absorber quickly attenuates the tire vibration and It plays a role in improving ground contact and running stability.

By the way, the riding feeling and the running stability have characteristics that are almost opposite to each other. That is, the damping force of the shock absorber should be lowered in order to enhance the riding feeling, and the damping force of the shock absorber should be increased in order to enhance the running stability. In a general shock absorber for a vehicle, it is necessary to give priority to safety while the vehicle is traveling, and it is necessary to design the vehicle so that the riding comfort is improved, with the traveling stability being considered first. For this reason, in general, the ride feeling is often insufficient.

In the shock absorber, a damping force is generated by the viscosity of the oil flowing through the piston valve while the piston equipped with the piston valve reciprocates in a storage tube filled with oil. That is, the damping force is generated by the piston valve. In a conventional piston valve of a shock absorber, as shown in FIG. 4, a piston 3 having a through hole 4 formed at the tip of a piston rod 2, a disc sheet 5, and a disc spring-shaped disc made up of a large number of discs. 6 is fitted and fixed by a nut 7.

In the conventional piston valve thus constructed, when the piston rod 2 rises in the storage tube 1, oil flows in the direction of the arrow in the figure. When the piston rod 2 moves at a medium and high speed (0.1 m / sec or more), the oil in the upper chamber 15 flows into the through hole 4 of the piston 3, and the disc sheet 5 and the disc 6 are curved downward. It flows out to the lower chamber 18 through the formed flow path. Moreover, the piston rod 2 moves at a low speed (0.1 m /
The piston 3 from the upper chamber 15
The oil that has flowed in through the through hole 4 of the disk seat 5
Further, the disk 6 is not bent, and these are discharged only through the orifices 16 formed on both sides of the disk sheet 5 in a non-curved state. In this way, the characteristic that the damping force changes in accordance with the moving speed of the piston rod 2 is provided.

However, in the above-mentioned low speed region, the damping force is generated only by the flow resistance of the oil passing through the orifice 16 of the disc seat 5 regardless of the moving speed of the piston rod 2, so that the piston rod 2 moves. An appropriate damping force cannot be obtained as the speed approaches the medium-high speed region.

For example, in the case of a so-called choppy ride in which a vehicle passes a road surface having continuous irregularities, the piston rod 2 of the shock absorber moves at the boundary between the low speed region and the medium and high speed regions. In this state, the damping force is generated almost only by the orifice 16 of the disc seat 5, so that a gentle riding feeling can be obtained in a low low speed region of, for example, 0.05 m / sec or less.
In the medium to low speed region of 05 m / sec to 0.2 m / sec, the riding feeling is deteriorated only by the damping force generated only by the orifice 16 of the disc seat 5.

[0008] For example, in the conventional shock absorber, there is a problem in that when the vehicle travels on a road surface having continuous irregularities such as a concrete paved road surface, a feeling of relatively hard riding is felt, and fatigue of the vehicle passenger is increased. there were.

[0009]

DISCLOSURE OF THE INVENTION The present invention is intended to solve such a problem and is intended for use in a low speed region (0.05 m / m).
Oil flows only through the orifice of the disc seat as in the past (seconds or less), but is formed on the piston rod other than the orifice of the disc seat in the medium and low speed region (0.05 m / sec to 0.2 m / sec). By allowing oil to flow through another internal flow path, the ride feeling can be felt even in the region where the piston lot moves at medium and low speeds (0.05 m / sec to 0.2 m / sec), such as in choppy riding. It is intended to be soft and reduce the fatigue of passengers.

[0010]

According to the present invention, as means for achieving the above-mentioned object, in the low-low speed region, the flow path is closed by the ball which receives the elastic force of the coil spring, and in the middle and low speed section. Forms a separate internal flow path inside the piston rod that allows the oil to flow from the upper chamber to the lower chamber against the elastic force of the coil spring, reducing the damping force in the middle and low speed sections and softening the riding feeling. ing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A piston valve for a shock absorber according to an embodiment of the present invention will be described below with reference to FIGS.

At the tip of the piston rod 2, a piston 3 having a through hole 4 formed therein, a disc sheet 5,
Disc spring-shaped discs 6 made up of a large number of sheets are fitted and fixed by nuts 7. In such a shock absorber piston valve, the piston rod 2 that contacts the space between the piston 3 and the disc seat 5
The oil inflow hole 8 is formed in the outer peripheral surface portion of the, and the oil discharge hole 17 is formed in the outer peripheral surface portion below the oil inflow hole 8.
Are formed. The internal flow path 1 has an inclined flow path 9 in the upper part, which is narrow between the holes 8 and 17 and wide in the lower part.
A coil spring 13 whose one end is fixed to the lower end of the piston rod 2 is provided inside the internal flow passage 10, and between the other end of the coil spring 13 and the inclined flow passage 9. A ball 14 is provided.

Further, one end of the coil spring 13 is fitted and fixed to a spring seat 12 projecting in the center of the inside of a spring fixing cap 11 screwed to the lower end of the piston rod 2.

The oil inflow hole 8 and the oil discharge hole 17 are also provided.
Are formed along the outer peripheral surface of the piston rod 2.

The piston valve of the shock absorber according to the embodiment of the present invention thus configured operates as follows. In the region where the piston rod 2 moves at a low low speed (0.05 m / sec or less), as shown in FIG.
Since the force of the oil introduced from the upper chamber 15 into the oil inflow hole 8 of the piston rod 2 through the through hole 4 of the piston 3 is smaller than the elastic force of the coil spring 13, the internal flow passage 10 is not opened, and the oil is transferred to the disc sheet. It flows only through the orifice 16 of No. 5, and a predetermined damping force is generated.

Therefore, in the low low speed region (0.05 m / sec or less), the damping force has a characteristic almost equal to that of the conventional shock absorber as shown in FIG. On the other hand, in the medium and low speed region (0.05 m / sec to 0.2 m / sec), the force of the oil flowing into the oil inflow hole 8 through the through hole 4 of the piston 3 causes the elastic force of the coil spring 13 to rebound. Therefore, the ball 14 that is in close contact with the surface of the inclined flow channel 9 descends, the internal flow channel 10 is opened, and the oil that has flowed into the internal flow channel 10 becomes
Spilled through 7.

Therefore, in this medium to low speed section, the oil flows out not only through the orifice 16 of the disk seat 5 but also through the internal flow passage 10 formed in the piston rod 2, so the damping force is shown in FIG. As described above, the characteristic is smaller than that of the conventional shock absorber. Therefore, compared to the conventional shock absorber having the piston valve, a softer riding feeling is provided.

[0018]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, when traveling on a road in which small unevenness is continuously formed on a road surface such as a concrete paved road, etc. / Sec to 0.2 m / sec), the oil also flows through the internal flow passage 10 formed inside the piston rod 2 in addition to the orifice 16 of the disc seat 5 of the piston valve of the shock absorber. As a result, the damping force of the shock absorber is reduced in the middle and low speed regions to give a vehicle occupant a soft riding feeling. Further, in this region of medium to low speed, the oil flows through the flow path formed by the curve of the orifice 16 of the disc sheet 5 and the disc 6 as in the conventional case, and the damping force having the same characteristic as in the conventional case is generated. The typical damping force characteristics are almost the same as in the conventional case. Further, as described above, the riding feeling at the time of choppy riding is improved, the traveling stability does not decrease, and the riding feeling and the traveling stability can be improved together.

Further, in the piston valve of the shock absorber of the present invention, the spring characteristic of the coil spring 13 can be arbitrarily set, and by appropriately setting this spring characteristic, an arbitrary damping force characteristic can be obtained. it can. Therefore, there is also an effect that the range of setting the damping force characteristic at the time of design is expanded, such that the damping force can be designed to be increased as necessary, and the flexibility at the time of design is improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an operating state when a piston rod moves in a low-low speed region in a piston valve of a shock absorber according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an operating state when the piston rod of the shock absorber piston valve of FIG. 1 moves in a medium to low speed region.

FIG. 3 is a damping force diagram showing damping force characteristics of a piston valve of a shock absorber according to the present invention together with damping force characteristics of a piston valve of a conventional shock absorber.

FIG. 4 is a vertical cross-sectional view of a piston valve of a conventional shock absorber.

[Explanation of symbols]

 1 Storage Tube 2 Piston Rod 3 Piston 4 Through Hole 5 Disc Seat 6 Disc 7 Nut 8 Oil Inlet Hole 9 Inclined Flow Path 10 Internal Flow Path 11 Spring Fixing Cap 12 Spring Seat 13 Coil Spring 14 Ball 17 Oil Discharge Hole

Claims (3)

[Claims] 1. A piston (3) having a through hole (4) formed therein, a disc sheet (5), and a disc (6) consisting of a large number of discs are fitted at the tip of a piston rod (2). , In a piston valve of a shock absorber fixed by a nut (7), an oil inflow hole (8) is formed on an outer peripheral surface of a piston rod (2) in a portion in contact with a space between the piston (3) and the disc seat (5). Is formed, and an oil discharge hole (17) is formed on the outer peripheral surface of the piston rod below the oil inflow hole (8), and an upward flow path is narrow between these holes (8, 17) and a downward flow path is wide. The internal flow path (1
0), a coil spring (13) having one end fixed to the lower end of the piston rod (2) is provided in the internal flow path (10), and the coil spring (13) is provided.
A piston valve for a shock absorber, characterized in that a ball (14) is provided between the other end portion and the inclined flow path (9). 2. One end of the coil spring (13) is
The spring seat (12) projecting from the inner center of a spring fixing cap (11) screwed to the lower end of the piston rod (2) is fitted and fixed to the spring seat (12). Shock absorber piston valve. 3. The oil inflow hole (8) and the oil discharge hole (17) are provided along the outer peripheral surface of the piston rod (2).
The piston valve of the shock absorber according to claim 1 or 2, wherein a plurality of piston valves are formed.