KR101257346B1 - Hydraulic damper with variable flow passage - Google Patents

Abstract

The present invention is a cylinder having a predetermined space therein; A piston having a piston rod penetrating the upper portion of the cylinder in the vertical direction and a piston head connected to an end of the piston rod and moving in the cylinder in the vertical direction; A working fluid filled in the cylinder; A first orifice formed through the piston head in a vertical direction; A second orifice spaced apart from the central axis of the piston head by a predetermined distance and penetrating the piston head in a vertical direction, the second orifice having a smaller flow path size than the first orifice; And an orifice cap installed on the open top and bottom of the first orifice so as to be opened and closed, respectively, the orifice cap being opened or closed according to the direction of movement and the magnitude of vibration of the piston head. In this regard, the flow path of the first orifice may be selectively opened and closed according to the magnitude of external vibration to generate a damping force that may correspond to a vibration in a wide frequency range.

Description

Hydraulic damper with variable flow passage

The present invention relates to a hydraulic damper having a variable flow path, and more particularly, a flow path of the first orifice can be selectively opened and closed according to the magnitude of external vibration to generate a damping force that can cope with vibration in a wide frequency range. A hydraulic damper having a variable flow path.

In general, the hydraulic damper is a damper that uses the turbulent resistance of the fluid as a damping force, and is a device that generates fluid resistance by controlling the flow path size of the orifice through which the fluid passes.

These hydraulic dampers are divided into a direct type and a lever type, the direct type has a piston type and the lever type has a rotary wing type and a piston type. Among these, the linear piston type hydraulic damper is used for shock absorbing of automobiles, railway vehicles, aircraft wheels, washing machines, piping systems, and the like when the doors are opened and closed.

1 is a cross-sectional view schematically showing a linear piston type hydraulic damper according to the prior art. As shown in FIG. 1, the hydraulic damper according to the prior art includes a piston 10 and a cylinder 20. .

The piston 10 is composed of a piston head 11 and a piston rod 12, the piston head 11 is formed by passing through an orifice 14 in the circumferential direction, the outer peripheral end of the piston head 11 is annular O-ring 13 is provided.

The cylinder 20 is separated into the upper chamber 21 and the lower chamber 22 based on the piston head 11 of the piston 10 inserted therein, and is formed in a plate shape inside the lower chamber 22. The gas chamber floating piston 24 is provided, and the outer circumferential end of the gas chamber floating piston 24 has a rounded shape corresponding to the shape of the o-ring 25 to facilitate the coupling of the o-ring 25. In addition, a predetermined fluid is filled in the cylinder 20.

By this structure and form, the piston 10 composed of the piston head 11 and the piston rod 12 moves up and down in the cylinder 20 composed of the upper chamber 21 and the lower chamber 22, As the piston 10 moves, the fluid filled in the cylinder 20 flows toward the upper chamber 21 or the lower chamber 22.

As a result of the flow of the fluid according to the movement of the piston head 11 inside the cylinder 20, a pressure difference is generated between the upper chamber 21 and the lower chamber 22, thereby generating a damping force in the hydraulic damper.

On the other hand, in order to compensate for the volume increase and decrease in the hydraulic damper according to the movement of the piston rod 12, the gas chamber floating by injecting a high pressure gas into the lower portion of the gas chamber floating piston 24 installed in the lower chamber 22 The piston 24 is free to move up and down, thereby compensating for the increase and decrease in volume in the cylinder 20 according to the volume change caused by the up and down movement of the piston 10.

However, in the hydraulic damper according to the related art, the damping force generated by the pressure difference generated between the upper chamber 21 and the lower chamber 22 in accordance with the movement of the piston head 11 is fixed at a constant value, thereby providing various damping forces. There was a problem that can not satisfy the requirements of.

For example, in the case of a special use damper, such as a damper for washing machines, there is a need to have both a vibration damping capability with little damping force and a damping ability with a large damping force. However, the damper according to the prior art at the time of high frequency vibration has a problem in that it does not behave as a damper but loses the dust-proofing ability because the damper behaves as an elastic body by friction and the like and eventually transmits vibration.

The present invention has been invented to solve the above problems, and an object thereof is to provide a hydraulic damper having a variable flow path that can satisfy both a case where a low damping force is required and a case where a high damping force is required.

In other words, the present invention operates as a damper when a large vibration of a low frequency is applied to damp the vibration, and when a small vibration of a high frequency is applied, the hydraulic pressure having a variable flow path that can secure the dustproof performance by lowering the damping force. The purpose is to provide a damper.

According to an aspect of the present invention for achieving the above object, a cylinder having a predetermined space therein; A piston having a piston rod penetrating the upper portion of the cylinder in the vertical direction and a piston head connected to an end of the piston rod and moving in the cylinder in the vertical direction; A working fluid filled in the cylinder; A first orifice formed through the piston head in a vertical direction; A second orifice spaced apart from the central axis of the piston head by a predetermined distance and penetrating the piston head in a vertical direction, the second orifice having a smaller flow path size than the first orifice; And an orifice cap installed on the open top and bottom of the first orifice so as to be openable and closed, respectively, the orifice cap being opened or closed according to the moving direction and the magnitude of vibration of the piston head.

Preferably, the working fluid is a magnetic flow fluid, characterized in that the piston head is provided with a magnetic induction coil to form a magnetic field according to the application of an external current.

Preferably, the first orifice is characterized by consisting of a plurality of radially spaced apart from each other radially along the circumferential direction of the piston head.

Preferably, the orifice cap is opened or closed by the pressure of the working fluid passing through the first orifice.

Preferably, the second orifice has an annular cross section surrounding the central axis of the piston head.

Preferably, the piston head is characterized in that it has a play with the inner wall of the cylinder.

The hydraulic damper having a variable flow path according to the present invention has an effect of generating a damping force capable of responding to a vibration in a wide frequency range by selectively opening and closing the flow path of the first orifice according to the magnitude of the external vibration.

Furthermore, the hydraulic damper having a variable flow path according to the present invention is capable of generating a damping force that can cope with vibration in a wider frequency range by changing the flow characteristics of the magnetic fluid along with the flow rate of the first orifice. There is.

1 is a cross-sectional view schematically showing a linear piston type hydraulic damper according to the prior art,
FIG. 2 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a first embodiment of the present invention, and showing an operating state of an orifice cap when vibration of high frequency occurs.
3 and 4 are cross-sectional views schematically showing a hydraulic damper having a variable flow path according to a first embodiment of the present invention, showing the operating state of the orifice cap when a low frequency vibration occurs;
FIG. 5 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a second embodiment of the present invention, illustrating an operation state of an orifice cap when vibration of high frequency occurs.
6 and 7 are cross-sectional views schematically showing a hydraulic damper having a variable flow path according to a second embodiment of the present invention, and showing an operating state of an orifice cap when vibration of a low frequency occurs.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a hydraulic damper having a variable flow path according to the present invention. In the following description of the present invention, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the technical scope of the present invention. Will be.

(Embodiment 1)

FIG. 2 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a first embodiment of the present invention, illustrating an operation state of an orifice cap when vibration of high frequency occurs, and FIGS. 3 and 4 3 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a first embodiment of the present invention, and illustrates an operation state of an orifice cap when vibration of a low frequency occurs.

2 to 4, the hydraulic damper having the variable flow path according to the first embodiment of the present invention includes a cylinder 110, a piston 120, a working fluid 130, and a first orifice 140. , The second orifice 150 and the orifice cap 160 is configured.

The cylinder 110 is a cylindrical body, and has a predetermined space in which the piston 120 can be moved in the vertical direction.

The piston 120 consists of a piston rod 121 and a piston head 122. The piston rod 121 penetrates the upper portion of the cylinder 110 in a vertical direction to connect a vibration generating medium (not shown) located outside the cylinder 110 and the piston head 122 located inside the cylinder 110. Here, the vibration generating medium means a tub of a washing machine or a compressor of a refrigerator. The piston head 122 is connected to the end of the piston rod 121 in the cylinder 110 to move integrally with the piston rod 121 in the cylinder 110. That is, the piston 120 is moved in the vertical direction in the cylinder 110.

The working fluid 130 acts as a resistance to the piston head 122 filled inside the cylinder 110 and moved upwards or downwards, thus generating a damping force. Preferably the working fluid 130 is a viscous oil.

The first orifice 140 is formed by penetrating the piston head 122 in the vertical direction. The first orifice 140 is a passage through which the working fluid 130 moves according to the movement of the piston head 122. The flow path is opened or closed by an orifice cap 160 to be described later. Thus, the damping force of the working fluid 130 can be varied.

Preferably, the first orifice 140 is located in the outward direction from the center of the piston head 122, a plurality of radially spaced apart from each other radially from the central axis of the piston head 122. Accordingly, the piston head 122 in which the first orifice 140 is formed has a shape similar to the ball bearing from which the ball is removed. The arrangement of the first orifice 140 serves to balance the piston head 122 when the piston head 122 moves up and down.

Like the first orifice 140, the second orifice 150 penetrates the piston head 122 in the vertical direction. The second orifice 150 is positioned spaced apart from the first orifice 140 from the central axis of the piston head 122. In this case, the second orifice 150 has a smaller flow path size than the first orifice 140. The flow path size of the second orifice 150 is about 1/4 of the flow path size of the first orifice 140.

Preferably, the second orifice 150 has an annular cross section surrounding the central axis of the piston head 122. That is, the second orifice 150 is formed at a position closer to the central axis of the piston head 122 than the first orifice 140.

The orifice cap 160 is installed to be opened and closed at the open top and bottom of the first orifice 140, respectively. The orifice cap 160 is opened or closed when the piston head 122 is moved upwards or downwards by external vibration to adjust the magnitude of the fluid resistance of the working fluid 130.

Specifically, the orifice cap 160 is opened or closed by the pressure of the working fluid 130 passing through the first orifice 140 when the piston head 122 is moved in accordance with the occurrence of vibration from the outside, the cylinder ( 110) Change the fluid resistance inside. In other words, the orifice cap 160 is mounted to the piston head 122 in a state of being elastically supported, for example, so that the first orifice 140 is normally kept open. Accordingly, the first orifice 140 may be closed by the fluid pressure generated at the same time as the piston head 122 moves up and down.

On the other hand, the piston head 122 preferably has a minimum clearance with the inner wall of the cylinder (110). The clearance between the piston head 122 and the inner wall of the cylinder 110 is such that when the first orifice 140 is closed by the orifice cap 160, the working fluid 130 inside the cylinder 110 may move. The minimum passage is to ensure that there is.

In addition, a floating piston (not shown) is installed at an inner lower portion of the cylinder 110 to divide the cylinder 110 up and down. The lower part of this floating piston is filled with gas, such as nitrogen. The floating piston oscillates in response to the volume change caused by the vertical movement of the piston 110 to compensate for the increase and decrease of the volume in the cylinder 110.

Hereinafter, an operation example of a hydraulic damper having a variable flow path according to the first embodiment of the present invention will be described with reference to FIGS. 2 to 4.

First, when a small vibration of a high frequency occurs, a small force is transmitted to the piston head 122, so that the operation displacement of the piston head 122 is also smaller than the required displacement for the orifice cap 160 to close. Thus, as shown in FIG. 2, the orifice cap 160 remains open.

As a result, since the fluid inside the cylinder 110 moves freely through both the first orifice 140 and the second orifice 150, the damping force due to the fluid resistance hardly occurs. Therefore, it has a dust-proof ability which can respond to the small vibration of a high frequency.

On the other hand, when a large vibration of the low frequency is generated, a large force is transmitted to the piston head 122, so that the operation displacement of the piston head 122 is also larger than the required displacement for closing the orifice cap 160. Thus, as shown in FIGS. 3 and 4, the orifice cap 160 is in a closed state.

At this time, when the operation direction of the piston head 122 is directed downward as shown in Figure 3, only the orifice cap 160 in the lower portion of the piston head 122 is in a closed state. On the other hand, when the operation direction of the piston head 122 is directed upward as shown in FIG. 4, only the orifice cap 160 on the top of the piston head 122 is in a closed state.

As a result, the working fluid 130 inside the cylinder 110 is not moved through the first orifice 140 and is moved only through the second orifice 150 having a smaller flow path size than the first orifice 140. , Large damping force is generated by fluid resistance. Therefore, it has a vibration damping ability which can cope with the big vibration of low frequency.

As described above, the hydraulic damper having the variable flow path according to the first embodiment of the present invention generates a damping force proportional to the amount of current, thereby ensuring a damping performance corresponding to the magnitude of the applied vibration.

(Second Embodiment)

FIG. 5 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a second embodiment of the present invention, illustrating an operation state of an orifice cap when vibration of high frequency occurs. FIGS. 6 and 7 2 is a cross-sectional view schematically illustrating a hydraulic damper having a variable flow path according to a second exemplary embodiment of the present invention, and illustrates an operation state of an orifice cap when vibration of a low frequency occurs.

5 to 7, the hydraulic damper having the variable flow path according to the second embodiment of the present invention is almost the same configuration as the hydraulic damper having the variable flow path according to the first embodiment, and the working fluid ( 130 is different from the first embodiment.

In the hydraulic damper having the variable flow path according to the second embodiment of the present invention, a magneto-rheological fluid is used as the working fluid 130. Accordingly, the second embodiment of the present invention further includes a magnetic induction coil 170 for changing the rheological properties (viscosity, plasticity, elasticity) of the magnetic flow fluid, that is, the MR fluid.

The magnetic induction coil 170 is inserted into the central side of the piston head 122 to form a magnetic field according to the application of external current.

On the other hand, when the magnetic flow fluid is briefly described, the magnetic flow fluid emits a fluid whose rheological properties (viscosity, plasticity, elasticity) can be reversibly changed in response to the magnitude of the magnetic field, and yields when the strength of the magnetic field increases. The stress is increased to have the property of resisting external movement. These magnetic fluids can be used in a variety of mechanical devices, such as harmonic dampers, vibration isolation systems, clutches, brakes, friction devices, and robotic arms.

An operation example of the hydraulic damper having the variable flow path according to the second embodiment of the present invention using such a magnetic flow fluid as the working fluid 130 will be described with reference to FIGS. 5 to 7.

First, when a small vibration of a high frequency occurs, a small force is transmitted to the piston head 122, so that the operation displacement of the piston head 122 is also smaller than the required displacement for the orifice cap 160 to close. Thus, as shown in FIG. 5, the orifice cap 160 is all kept open. In this case, since no current is applied to the magnetic induction coil 170, the rheological properties of the working fluid 130, that is, the magnetic flow fluid, are not changed.

As a result, since the working fluid 130 inside the cylinder 110 is free to move through both the first orifice 140 and the second orifice 150, the damping force due to the fluid resistance hardly occurs. Therefore, it has a dust-proof ability which can respond to the small vibration of a high frequency.

On the other hand, when a large vibration of the low frequency occurs, a large force is transmitted to the piston head 122, so that the operation displacement of the piston head 122 is also larger than the required displacement for the orifice cap 160 to close. Thus, as shown in FIGS. 6 and 7, the orifice cap 160 is in a closed state. At this time, a current is applied to the magnetic induction coil 170, so that the magnetic induction coil 170 generates a magnetic field. This changes the rheological properties of the working fluid 130, ie the magnetic flow fluid. In other words, the yield stress of the magnetic flow fluid is increased.

Therefore, the hydraulic damper according to the present invention not only generates a damping force of a greater magnitude than that of the case where the first orifice 140 is opened, but also increases the yield stress of the magnetic flow fluid in the first embodiment of the present invention. The orifice 140 generates a damping force of a greater magnitude than when the orifice 140 is closed. Therefore, it has a vibration damping ability that can cope with a very large vibration at low frequency.

Specifically, when the operation direction of the piston head 122 is directed downward as shown in FIG. 6, only the orifice cap 160 under the piston head 122 is in a closed state. On the other hand, when the operation direction of the piston head 122 is directed upward as shown in FIG. 7, only the orifice cap 160 on the top of the piston head 122 is in a closed state.

As a result, the working fluid 130 inside the cylinder 110 is not moved through the first orifice 140 and is moved only through the second orifice 150 having a smaller flow path size than the first orifice 140. , Large damping force is generated by fluid resistance.

Furthermore, as described above, in the hydraulic damper having the variable flow path according to the second embodiment of the present invention, not only the flow path of the first orifice 140 is closed by the orifice cap 160, but also the magnetic flow due to the application of current. Since the yield stress of the fluid can be increased, the damping force is generated larger than the damping force in the first embodiment, thus ensuring a damping performance corresponding to the vibration magnitude in a wider frequency range than the first embodiment. can do.

Meanwhile, in the present invention, the working fluid is described and illustrated as using a magnetic flow fluid, but the hydraulic damper having the variable flow path according to the present invention has an electric flow fluid whose reversible rheological properties are changed corresponding to the strength of the electric field. It is easy to see that Electro-rheological Fluid, ie, ER fluid, may be used.

The embodiments of the present invention described above are merely illustrative of the technical idea of the present invention, and the scope of protection of the present invention should be interpreted according to the claims. In addition, one of ordinary skill in the art to which the present invention pertains will be capable of various modifications and variations without departing from the essential characteristics of the present invention, all technical ideas within the scope equivalent to the present invention of the present invention It should be interpreted as being included in the scope of rights.

110: cylinder 120: piston
121: piston rod 122: piston head
130: working fluid 140: first orifice
150: second orifice 160: orifice cap
170: magnetic induction coil

Claims (6)

A cylinder 110 having a predetermined space therein;
A piston having a piston rod 121 penetrating the cylinder 110 in a vertical direction and a piston head 122 connected to an end of the piston rod 121 and moving vertically in the cylinder 110. 120);
A magnetic flow fluid 130 filled in the cylinder 110;
A magnetic induction coil 170 installed at the piston head 122 to form a magnetic field according to the application of an external current;
A first orifice 140 formed through the piston head 122 in a vertical direction;
The first orifice 140 is spaced apart from the central axis of the piston head 122 by a predetermined distance, and is formed by penetrating the piston head 122 in the vertical direction, the flow path size smaller than the first orifice 140 A second orifice 150 having; And
Installed at the top and bottom of the first orifice 140, respectively, depending on the pressure of the magnetic flow fluid 130 passing through the first orifice 140, the moving direction and the operation displacement of the piston head 122 And includes an orifice cap 160 to be opened and closed with,
The magnetic induction coil 170 is applied with a current when the first orifice 140 is closed in response to low frequency vibration to increase the yield stress of the magnetic flow fluid 130 around the piston head 122. Hydraulic damper having a variable flow path, characterized in that.
delete The method of claim 1,
The first orifice 140 is a hydraulic damper having a variable flow path, characterized in that consisting of a plurality of radially spaced apart from each other radially along the circumferential direction of the piston head (122).
delete The method of claim 1,
The second orifice (150) is a hydraulic damper having a variable flow path characterized in that it has an annular cross-section surrounding the central axis of the piston head (122).
The method of claim 1,
The piston head 122 has a hydraulic damper having a variable flow path, characterized in that it has a clearance to the inner wall of the cylinder (110).

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