KR101756421B1 - Shock absorber with a frequency unit - Google Patents

Abstract

The present invention relates to a frequency-sensitive shock absorber capable of simultaneously satisfying riding comfort and adjustment stability by having a damping force characteristic that is dictated by frequency in compression and extension motion of a piston valve in a cylinder of a shock absorber.
According to the present invention, there is provided a cylinder assembly comprising: a cylinder filled with a working fluid; A piston rod having one end located inside the cylinder and the other end extending outside the cylinder; A main piston valve assembly installed at one end of the piston rod and operated in a state where the inside of the cylinder is divided into an upper chamber and a lower chamber to generate a damping force varying with a moving speed; A sensing unit installed on the piston rod together with the main piston valve assembly and generating a damping force varying with a frequency; Wherein the sensing unit includes an auxiliary valve assembly mounted at a lower end of the piston rod to be disposed below the main piston valve assembly and a free piston assembly mounted to the piston rod to be disposed above the main piston valve assembly, And a bypass flow path formed in the piston rod such that a working fluid can flow between the upper chamber and the lower chamber without passing through the main piston valve assembly.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a frequency-responsive shock absorber,

The present invention relates to a frequency-responsive shock absorber, and more particularly, to a frequency-responsive shock absorber which has a damping force characteristic specific to a frequency in compression and extension motion of a piston valve in a cylinder of a shock absorber, Sensitive shock absorber.

Generally, a vehicle is equipped with a shock absorber for improving ride comfort by absorbing shocks or vibrations that the axle receives from the road surface when the vehicle is traveling, and a shock absorber is used as one of such shock absorbers.

The shock absorber operates according to the vibration of the vehicle according to the road surface condition. At this time, depending on the operating speed of the shock absorber, that is, the operating speed is fast or slow, the damping force generated in the shock absorber changes.

The riding comfort and driving stability of the vehicle can be controlled by adjusting the damping force characteristics generated by the shock absorber. Therefore, when designing a vehicle, it is very important to adjust the damping force characteristics of the shock absorber.

Conventional piston valves are designed to have constant damping characteristics at high speed, medium speed, and low speed by using a single flow path. Therefore, if the low speed damping force is lowered to improve ride comfort, the second speed damping force may be affected. In addition, the conventional shock absorber has a structure in which the damping force changes in accordance with the speed change of the piston regardless of the frequency or the stroke. Since the damping force changed only in accordance with the speed change of the piston generates the same damping force in various road surface conditions, it is difficult to simultaneously satisfy the ride comfort and the adjustment stability.

Accordingly, it is necessary to continuously research and develop a valve structure of a shock absorber that can vary the damping force according to various road surface conditions, that is, the excitation frequency and stroke, and can satisfy the ride comfort and the adjustment stability of the vehicle at the same time.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a frequency-sensitive shock absorber including a sensing unit for generating a damping force varying according to a frequency to satisfy a ride comfort and an adjustment stability of a vehicle.

According to an aspect of the present invention, there is provided a frequency-sensitive shock absorber in which a damping force varies according to a frequency, the shock-absorbing shock absorber comprising: a cylinder filled with a working fluid; A piston rod having one end located inside the cylinder and the other end extending outside the cylinder; A main piston valve assembly installed at one end of the piston rod and operated in a state where the inside of the cylinder is divided into an upper chamber and a lower chamber to generate a damping force varying with a moving speed; A sensing unit installed on the piston rod together with the main piston valve assembly and generating a damping force varying with a frequency; Wherein the sensing unit includes an auxiliary valve assembly mounted at a lower end of the piston rod to be disposed below the main piston valve assembly and a free piston assembly mounted to the piston rod to be disposed above the main piston valve assembly, And a bypass flow path formed in the piston rod such that a working fluid can flow between the upper chamber and the lower chamber without passing through the main piston valve assembly.

The auxiliary valve assembly includes a housing mounted on a lower end of the piston rod and having an interior space therein, an auxiliary valve body mounted on the housing and having auxiliary compression passages and auxiliary rebound passages through which a working fluid passes during operation of the shock absorber, An auxiliary compression valve disposed at an upper portion of the auxiliary valve body to generate a damping force against the pressure of the working fluid that has passed through the auxiliary compression passage; And auxiliary rebound valve means for generating a damping force against the pressure of the fluid.

The free piston assembly includes a free piston installed to open or close the bypass passage while moving up and down along the piston rod, and a free piston, And upper and lower elastic means for retaining the upper and lower elastic means.

The free piston may be disposed between the main piston valve assembly and the stopping unit provided on the piston rod.

The upper elastic means may be disposed between the free piston and the stooping unit, and the lower elastic means may be disposed between the free piston and the main piston valve assembly.

Wherein the bypass passage includes a vertical flow passage formed inside the piston rod so as to have a length longer than that of the main piston valve assembly and a bypass passage formed in the piston rod at a position above the main piston valve assembly, And a left and right directional flow path.

An upper groove and a lower groove may be formed on the surface of the piston rod so that the working fluid can flow through the main piston valve assembly when the free piston moves up and down by an external force.

According to the present invention as described above, it is possible to provide a frequency-sensitive shock absorber including a sensitive unit that generates a damping force varying in frequency.

Accordingly, the shock absorber manufactured by the manufacturing method according to the present invention has a damping force characteristic according to the frequency (or amplitude) of an impact input to the shock absorber through a specific road surface during operation of the piston valve moving in the cylinder of the shock absorber So that it is possible to satisfy both the ride comfort and the adjustment stability of the vehicle.

1 is a sectional view showing a valve structure of a frequency-responsive shock absorber according to the present invention,
FIG. 2 is a sectional view for explaining fluid flow through a valve structure of a frequency-responsive shock absorber according to the present invention at a high frequency (exhaust width)
3 is a cross-sectional view for explaining fluid flow through a valve structure of a frequency-sensitive shock absorber according to the present invention at low frequency extension, and
4 is a cross-sectional view of a main part for explaining fluid flow through a valve structure of a frequency-responsive shock absorber according to the present invention at low-frequency compression.

Hereinafter, a valve structure of a frequency-sensitive shock absorber according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

1 to 4, a frequency-responsive shock absorber according to the present invention includes a substantially cylindrical cylinder 10 in which a working fluid such as oil is filled, a cylinder 10 having one end located inside the cylinder, And a piston rod (20) extending outwardly of the piston rod (20).

The valve structure of the shock absorber according to the present invention is characterized in that a shock absorber valve structure provided at one end of the piston rod 20 operates in a state where the cylinder is divided into an upper chamber 11 and a lower chamber 12, And a sensing unit mounted on the piston rod 20 together with the main piston valve assembly 30 and generating a damping force varying with frequency.

The main piston valve assembly 30 and the sensitive unit are installed on one end side of the piston rod 20. The other end side of the piston rod 20 is slidably movable with respect to the rod guide and the oil seal, and extends axially through the cylinder to the outside of the cylinder (not shown).

The main piston valve assembly 30 is formed with at least one main compression passage 32 through which the working fluid passes during compression of the shock absorber and at least one main rebound passage 33 through which the working fluid passes during the extension of the shock absorber Main compression valve means 35 disposed at the upper portion of the main piston body 31 to generate a damping force against the pressure of the working fluid that has passed through the main compression passage 32, And a main rebound valve means 37 disposed at a lower portion of the piston main body 31 for generating a damping force against the pressure of the working fluid passing through the main rebound passage 33.

The outer peripheral surface of the main piston body 31 may be provided with a band 39 made of Teflon for adhesion with the inner circumferential surface of the cylinder 10 and prevention of abrasion.

The sensing unit according to the present invention includes an auxiliary valve assembly 110 mounted at the lower end of the piston rod 20 so as to be disposed below the main piston valve assembly 30, A free piston assembly 130 mounted to the piston rod 20 and a piston rod 20 for allowing the working fluid to flow between the upper chamber 11 and the lower chamber 12 without passing through the main piston valve assembly 30. [ The bypass flow paths 151 and 152 are formed in the bypass flow paths 151 and 152, respectively.

The auxiliary valve assembly 110 includes a hollow housing 111 mounted at the lower end of the piston rod 20 and hollow inside thereof and a lower end fixed to the lower end of the housing 111. When the shock absorber is compressed, The auxiliary valve body 112 having at least one auxiliary compression passage 113 and at least one auxiliary rebound passage 114 through which the working fluid passes during the extension of the shock absorber, An auxiliary compression valve means 115 disposed at the lower portion of the auxiliary valve body 112 for generating a damping force against the pressure of the working fluid that has been disposed through the auxiliary compression passage 113 and passes through the auxiliary rebound passage 114 And auxiliary rebound valve means (116) for generating a damping force against the pressure of one working fluid. The auxiliary valve main body 112 is provided with a fixing member 112 formed of rivets or bolts and nuts at the center of the auxiliary valve body 112 so that the auxiliary compression valve means 115 and the auxiliary rebound valve means 116 can be disposed on the upper and lower portions of the auxiliary valve body 112, (117).

The auxiliary valve body 112 of the auxiliary valve assembly 110 is fixed to the lower portion of the main piston valve assembly 30 by the housing 111. The inner space 111a of the housing 111 surrounded by the housing 111 and the auxiliary valve body 112 is connected to the bypass passage 111 formed in the piston rod 20, And can communicate with the upper chamber 11 through the first and second chambers 151 and 152, respectively.

The free piston assembly 130 includes a free piston 131 installed to open or close the bypass flow paths 151 and 152 formed in the piston rod 20 while moving up and down along the piston rod 20, The upper and lower elastic means 133 and 135 for pressing the free piston 131 up and down so that the free piston 131 can keep the bypass flow paths 151 and 152 closed when an external force is not applied, .

The free piston 131 is installed in the piston rod 20 to prevent the main piston valve assembly 30 or the like from directly colliding with a load guide (not shown) that closes the upper end of the shock absorber directly when the shock absorber is fully extended And the main piston valve assembly 30, as shown in Fig. The free piston 131 is vertically moved between the stapling unit 40 and the main piston valve assembly 30 by an external force so that the free piston 131 is moved to the free position The upper elastic means 133 is disposed between the free piston 131 and the stopping unit 40 so that the piston 131 can be positioned and the lower elastic means 135 is disposed between the free piston 131 and the main piston valve assembly & (30).

The stopping unit 40 may be composed of an elastic body such as rubber and a support coupled to the piston rod so as to fixably support the elastic body to the piston rod.

The free piston 131 is installed to move up and down in accordance with the frequency (amplitude). The upper elastic means and the lower elastic means can be any one selected from a spring, a disk and a clip, and any means can be utilized as long as it can support the free piston 131 while having elasticity. The shape and elastic modulus of the upper elastic means 133 and the lower elastic means 135 may be different from each other and may be variously changed in design.

The upper surface of the free piston 131 may be provided with a seating portion on which the lower end of the upper elastic means 133 can be seated and the upper end of the lower elastic means 135 may be seated on the lower surface of the free piston 131 Can be formed. Bands 137 and 138 made of, for example, Teflon can be attached to the inner and outer circumferential surfaces of the free piston 131 in the same manner as the main piston valve assembly for smooth sliding motion.

The bypass flow paths 151 and 152 formed in the piston rod 20 are formed along the central axis in the interior of the piston rod 20 so as to have a length longer than the entire height of the main piston valve assembly, A vertical flow passage 151 formed along the vertical direction and a left and right flow passage 152 formed in the piston rod 20 in communication with the vertical flow passage 151 and above the main piston valve assembly 30 do. 1 to 4 illustrate that the left and right direction flow path 152 is formed perpendicular to the longitudinal direction of the piston rod 20, but it is needless to say that it may be formed to be inclined.

When the free piston 131 is moved up and down by a predetermined distance or more by an external force so that the working fluid can flow through the main piston valve assembly 30, Grooves 22 are formed. The upper groove 21 is formed to be spaced upward from the opening of the right and left flow passage 152 and the lower groove 22 is formed to be spaced apart from the opening of the right and left flow passage 152 downward. When the upper groove 21 and the lower groove 22 are directly connected to the left and right flow passages 152, the bypass passages 151 and 152 can not be completely closed by the free piston 131, It is preferable that the opening of the bypass flow path and the upper and lower grooves 21 and 22 of the bypass flow path are spaced apart from each other.

Hereinafter, the operation of the valve structure according to the present invention will be described with reference to Figs. 2 to 4. Fig.

The position of the free piston 131 is shown in FIG. 2, and the position of the free piston 131 is shown in FIG. 3 at the time of low frequency (ie, large amplitude) extension (rebound) 4 shows the position of the free piston 131 during low frequency (i.e., large amplitude) compression. The free piston 131 can move while compressing the upper elastic means 133 or the lower elastic means 135 when an external force such as inertia and working fluid pressure is applied. That is, if the magnitude of the external force acting on the free piston 131 is large enough to compress the upper elastic means 133 or the lower elastic means 135, the free piston 131 moves upward or downward.

2 shows a state in which the piston rod of the shock absorber has a small amplitude and a high frequency so that the magnitude of the external force applied to the free piston 131 is large enough to compress the upper elastic means 133 and the lower elastic means 135 The degree of compression of the upper elastic means 133 and the lower elastic means 135 is not so large and the state in which the free piston 131 maintains the state in which the bypass passage is closed is shown. The state in which the free piston 131 does not actually move and the state in which the bypass passage is still closed even if the free piston 131 actually moves, Should be regarded as including.

The outer surface of the free piston 131 is in contact with the inner surface of the cylinder 10 over the entire circumference while the free piston 131 is not moved and the inner surface of the free piston 131 is in contact with the piston rod 20, The working fluid can not flow. At this time, as the free piston 131 vibrates finely, the working fluid of the upper chamber 11 under the free piston 131 flows to the lower chamber 12 through the main piston valve assembly 30, and the lower chamber 12 May flow through the main piston valve assembly 30 to the upper chamber 11 (i.e., the upper chamber below the free piston).

In a state where the free piston 131 is not moved, the auxiliary valve assembly 110 does not operate because there is no flow of working fluid through the bypass flow paths 151 and 152.

Thus, the damping force at high frequency and low amplitude is obtained by the main piston valve assembly 40.

3 and 4 show that the amplitude of the movement of the piston rod of the shock absorber is large and the frequency is small so that the magnitude of the external force acting on the free piston 131 can compress the upper elastic means 133 and the lower elastic means 135 The state is large enough.

As shown in FIG. 3, when the amplitude of the piston rod of the shock absorber moving at rebound is large and the vibration frequency is small, the free piston 131 moves downward and the bypass flow paths 151 and 152 can be opened.

When the bypass flow paths 151 and 152 are opened, the working fluid in the upper chamber 11 above the free piston 131 flows into the lower chamber 12 through the lower groove 22 and the main piston valve assembly 30, And can also flow to the lower chamber 12 through the bypass flow paths 151 and 152 and the auxiliary valve assembly 110.

4, when the amplitude of movement of the piston rod of the shock absorber at the time of compression is large and the vibration frequency is small, the free piston 131 moves upward and the bypass flow paths 151 and 152 can be opened.

When the bypass flow paths 151 and 152 are opened, the working fluid in the lower chamber 12 flows into the upper chamber 11 above the free piston 131 through the main piston valve assembly 30 and the upper groove 21, And flows to the upper chamber 11 through the auxiliary valve assembly 110 and the bypass flow paths 151 and 152. [

In this way, the damping force can be obtained by the main piston valve assembly 30 and the auxiliary valve assembly 110 of the sensitive unit at low frequency and high vibration.

As described above, the frequency-sensitive shock absorber according to the present invention has been described with reference to the drawings. However, the present invention is not limited to the above-described embodiments and drawings, It is to be understood that various changes and modifications may be made by those skilled in the art.

10: cylinder 11: upper chamber
12: Lower chamber 20: Piston rod
21: upper groove 22: lower groove
30: main piston valve assembly 31: main piston body
32: main compression passage 33: main rebound passage
35: main compression valve means 37: main rebound valve means
39: band 40: stopping unit
110: auxiliary valve assembly 111: housing
111a: internal space (of the housing) 112: auxiliary valve body
113: auxiliary compression passage 114: auxiliary rebound passage
115: auxiliary compression valve means 116: auxiliary rebound valve means
117: fixing member 130: free piston assembly
131: free piston 133: upper elastic means
135: lower elastic means 137, 138: band
151: Up and down flow passage 152:

Claims (7)

A frequency-responsive shock absorber in which the damping force varies with frequency,
A cylinder (10) filled with a working fluid;
A piston rod (20) having one end located inside the cylinder and the other end extending outside the cylinder;
A main piston valve assembly 30 installed at one end of the piston rod and operated in a state where the inside of the cylinder is divided into an upper chamber 11 and a lower chamber 12 to generate a damping force varying with a moving speed;
A sensing unit installed on the piston rod together with the main piston valve assembly and generating a damping force varying with a frequency; / RTI >
The sensing unit includes an auxiliary valve assembly (110) mounted at a lower end of the piston rod so as to be disposed below the main piston valve assembly, a free piston assembly (110) mounted to the piston rod to be disposed above the main piston valve assembly And a bypass passage (151, 152) formed in the piston rod such that a working fluid can flow between the upper chamber and the lower chamber without going through the main piston valve assembly,
The free piston assembly 130 includes a free piston 131 installed to open or close the bypass passage while moving up and down along the piston rod, And upper and lower elastic means (133, 135) for keeping the path channel closed,
The upper surface of the piston rod 20 is provided with an upper groove 21 and a lower groove 21 on the surface of the piston rod 20 so that the working fluid can flow through the main piston valve assembly 30 when the free piston 131 moves up and down by an external force. (22). The method according to claim 1,
The auxiliary valve assembly 110 includes a housing mounted on a lower end of the piston rod and having an interior space therein, a auxiliary compression passage 113 mounted on the housing and through which a working fluid passes during operation of the shock absorber, An auxiliary valve body provided on the auxiliary valve body and generating a damping force against the pressure of the working fluid passing through the auxiliary compression passage; And auxiliary rebound valve means (116) disposed under the auxiliary valve body for generating a damping force against the pressure of the working fluid passing through the auxiliary rebound passage. delete The method according to claim 1,
Wherein the free piston (131) is disposed between the main piston valve assembly (30) and the stopping unit (40) installed on the piston rod. The method of claim 4,
Wherein the upper elastic means (133) is disposed between the free piston and the stooping unit, and the lower elastic means (135) is disposed between the free piston and the main piston valve assembly. The method according to claim 1,
The bypass passage includes an up-and-down flow passage 151 formed inside the piston rod so as to have a longer length than the main piston valve assembly, And a left-right directional flow passage (152) formed in the piston rod. delete

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