Impact sensitive damper

Disclosed herein is an impact sensitive damper damping vibration transferred from a road surface to a vehicle, and more particularly, to an impact sensitive damper in which handling stability may be achieved in a low speed operating section of the damper and improvement of ride comfort may be achieved in a high speed operating section thereof. According to an exemplary embodiment of the present invention, there is provided an impact sensitive damper improving ride comfort by decreasing damping force when impact is applied to a vehicle, the impact sensitive damper including: a body valve body having compression channels and expansion channels formed therein; a fastener vertically penetrating through the body valve body; a dish shaped spring interposed between an upper portion of the body valve body and the fastener; and a disk shaped spring interposed between a lower portion of the body valve body and the fastener, wherein at the time of compression stroke when the impact is applied to the damper, the fastener is relatively displaced with respect to the body valve body due to elastic deformation of the dish shaped spring, such that the disk shaped spring and the lower portion of the body valve body are spaced apart from each other, thereby increasing a channel area of operating fluid.

This application claims priority from and the benefit of Korean Patent Application No. 10-2010-0052725, filed on Jun. 4, 2010, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

1. Technical Field

The present invention relates to an impact sensitive damper damping vibration transferred from a road surface to a vehicle, and more particularly, to an impact sensitive damper in which handling stability may be achieved in a low speed operating section of the damper and improvement of ride comfort may be achieved in a high speed operating section thereof.

2. Description of the Related Art

Generally, since vibration or impact is continuously applied from a road surface through wheels during driving of a vehicle, a damping device is installed between a car body and a car axis to prevent the impact or the vibration from being directly transferred to the car body, thereby improving ride comfort and to suppress irregular vibration of the car body, thereby improving handling stability.

Here, a connection device between the car body and the car axis, including this damping device is collectively referred to as a suspension device. The suspension device is configured to include a chassis spring alleviating impact, a damper controlling free vibration of the chassis spring to thereby improve ride comfort, a stabilizer preventing rolling, a rubber bushing, a control arm, and the like.

Among other components of the suspension device, the damper serves to suppress and damp vibration from a road surface and is mounted between the car body or a frame and a wheel. Particularly, the damper absorbs vertical vibrational energy of the car body to suppress the vibration, improve the ride comfort, protect loaded freight, and decrease dynamic stress of each part of the car body, thereby increasing durability. In addition, the damper suppresses downward movement of a spring to secure ground properties of a tire and suppresses a change in posture due to inertial force to improve movement performance of a vehicle.

The ride comfort and the handling stability may be appropriately adjusted according to damping force characteristics of the damper. That is, the damping force needs to be small in order to improve the ride comfort during general driving of the vehicle and the damping force needs to be large in order to improve the handling stability at the time of quick turning of the vehicle or during high speed driving thereof.

FIG. 1is a cross-sectional view showing a general damper according to the related art.

The damper40includes a cylinder43having operating fluid filled therein, a piston rod49having one end positioned inside the cylinder and the other end positioned outside of the cylinder, and a piston valve47mounted on one end of the piston rod49to thereby reciprocate within the cylinder43. The cylinder43is configured of an inner pipe41and an outer pipe42and has a body valve48mounted in a position facing the piston valve47at a distal end thereof.

An inner portion of the cylinder is divided into a compression chamber52and an expansion chamber51by the piston valve47, and the inner pipe41and the outer pipe42have a storing room46formed therebetween.

FIG. 2is a cross-sectional view of a body valve for describing generation of damping force of a damper.

As shown inFIG. 2, the body valve48includes compression channels61aand expansion channels61bvertically formed in a body valve body61and a suction valve assembly66mounted on an upper portion of the body valve body61, wherein the compression channels61aand the expansion channels61ballow the compression chamber52and the storing room46to be in communication with each other and the suction valve opens/closes the compression channels61a.

The suction valve assembly66includes slots62aand a single-plate suction valve62that are formed at the upper portion of the body valve body61and a retainer63, a suction spring64, and a washer65that are sequentially stacked on the slots and the suction valve, wherein the slots are in communication with the compression channels61a, the suction value62opens/closes the expansion channels61b, and the washer65supports the retainer63and the suction spring64.

Here, the retainer63maintains a clearance, the suction spring64elastically supports a rear surface of the suction valve62at an upper portion of the retainer63and always closely adheres the suction valve62to an upper surface of the body valve body61, and the washer65having holes65aformed therein is mounted on an upper portion of the suction spring64. The body valve body61includes a multi-plate disk68mounted on a lower portion thereof, wherein the multi-plate disk68opens/closes the compression channels61a.

At the time of the compression stroke of the piston rod49, operating fluid of the compression chamber52passes through the holes65aof the washer65, the slots62aof the suction valve62and the compression channels61aand then pushes the multi-plate disk68downwardly to move toward the storing room46while opening the multi-plate disk68, thereby generating the damping force. At the time of the expansion stroke thereof, the operating fluid in the storing room46passes through the extension channels61band then pushes the suction valve62upwardly to move to the compression chamber52while opening the suction valve62, thereby generating the damping force.

However, in the case of the body valve48according to the related art using the above-mentioned multi-plate disk68, as a load applied to the multi-plate disk68increases, a deformation amount rapidly decreases. Therefore, when large impact is transferred to the damper, a limitation in deformation of the multi-plate disk68occurs, such that the damping force rapidly increases, thereby deteriorating the ride comfort.

BRIEF SUMMARY

The present invention has been made in an effort to provide an impact sensitive damper in which both of a dish shaped spring and a disk shaped spring are used in a body valve of the damper to achieve smooth improvement of damping force at the time of conversion from a low speed operating section of the damper into a high speed operating section thereof, such that handling stability and improvement of ride comfort may be simultaneously achieved.

According to an exemplary embodiment of the present invention, there is provided an impact sensitive damper improving ride comfort by decreasing damping force when impact is applied to a vehicle, the impact sensitive damper including: a body valve body having compression channels and expansion channels formed therein; a fastener vertically penetrating through the body valve body; a dish shaped spring interposed between an upper portion of the body valve body and the fastener; and a disk shaped spring interposed between a lower portion of the body valve body and the fastener, wherein at the time of compression stroke when the impact is applied to the damper, the fastener is relatively displaced with respect to the body valve body due to elastic deformation of the dish shaped spring, such that the disk shaped spring and the lower portion of the body valve body are spaced apart from each other, thereby increasing a channel area of operating fluid.

The dish shaped spring may be fixedly mounted by a spring sheet interposed between the body valve body and the dish shaped spring.

The dish shaped spring, the spring sheet, the body valve body, and the disk shaped spring may be integrally assembled by the fastener.

DETAILED DESCRIPTION

Hereinafter, an impact sensitive damper according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. Damping force may be generated in a damper at the time of both of expansion stroke and compression stroke. However, since the present invention relates to the damping force at the time of the compression stroke, a body valve having an influence on generation of the damping force at the time of the compression stroke will be mainly described.

A cross-sectional view of a body valve assembly of an impact sensitive valve according to the prevent invention is shown inFIG. 3.

As shown inFIG. 3, an impact sensitive damper according to the prevent invention includes a cylindrical cylinder25having operating fluid filled therein and a body valve body11mounted in the cylinder25and having compression channels16and expansion channels17formed therein, having a predetermined interval therebetween. A bolt31may be fastened to a nut32while vertically penetrating through the body valve body11. Although an exemplary embodiment of the present invention describes a case in which the bolt31and the nut32are used as a fastener, other members such as a rivet, or the like, may be used as long as they may perform fastening.

The body valve body11includes a suction valve20mounted on an upper surface thereof and a spring sheet21and a dish shaped spring22sequentially stacked on the suction valve20. The spring sheet21is interposed between the suction valve20and the dish shaped spring22. The spring sheet21has a first surface abutting a surface of the suction valve20and a second surface facing and spaced apart from the surface of the suction valve20. In this configuration, the dish shaped spring22may maintain its position in a state in which it presses a washer23disposed on a lower surface of the nut32. Therefore, when the damper is operated in a low speed operating section in which pressure according to a flow of the operating fluid smaller than pressing force of the dish shaped spring22occurs, a position of a fastener by which the bolt31and the nut32are fastened to each other does not change.

However, when large impact is applied from a road surface to the damper, such that the damper is operated in a high speed operating section, pressure of the operating fluid instantaneously increases. This pressure is larger than the pressing force of the dish shaped spring22, such that deformation of the dish shaped spring22is generated. When the dish shaped spring22is pushed, the fastener by which the bolt31and the nut32are fastened to each other may be relatively displaced downwardly with respect to the body valve body11.

The high speed operation or the low speed operation of the damper in the present description is associated with an operating speed of a piston rod (not shown) included in the damper. Generally, when large impact is applied from a road surface to the damper during driving of a vehicle, the damper is operated at a high speed.

The body valve body11includes a disk shaped spring14mounted on a lower surface thereof. The disk shaped spring14includes a disk-S12and a plurality of disks13. In addition, a retainer24is mounted on a lower surface of the disk shaped spring14. The retainer24may serve to maintain a position of the disk shaped spring14even when the disk shaped spring14is bent downwardly by pressure of the operating fluid. A slit15is formed at an edge of the disk-S12, such that the operating fluid may flow through the slit15in the low speed operating section of the damper in which a flow of the operating fluid is weak, thereby generating damping force.

The body valve body11includes the suction valve20mounted on the upper surface thereof so as to close the expansion channel17. At the time of the compression stroke of the damper, the suction valve20closes the expansion channel17, such that the operating fluid flows through the compression channel16. At the time of the expansion stroke of the damper, the suction valve20closing the expansion channel17is opened upwardly, such that the operating fluid flows through the expansion channel17.

Although the flow of the operating fluid at the time of the expansion stroke is not shown inFIG. 3, at the time of the expansion stroke, the suction valve20is opened upwardly, such that the operating fluid may flow upwardly through the expansion channels17disposed at sides of the compression channels16based onFIG. 3.

The impact sensitive damper according to the present invention may adjust the damping force by using different characteristics of the disk shaped spring14and the dish shaped spring22. When viewing a curve ofFIG. 6in which deformation amounts according to loads of the dish shaped spring22and the disk shaped spring14according to the present invention are compared to each other, in the case of the disk shaped spring14, a displaceable amount increasingly decreases as the applied load increases. Therefore, when large impact is applied to the damper, the damping force rapidly increases. On the other hand, in the case of the dish shaped spring22, a displaceable amount increasingly increases as the applied load increases. Therefore, when large impact is applied to the damper, the rapid increase in the damping force may be prevented.

More specifically, when the pressure of the operating fluid smaller than force with which the dish shaped spring22presses the washer23is transferred to the body valve assembly, the disk shaped spring14may be deformed before the dish shaped spring22is deformed. A small space is formed between the body valve body11and the disk shaped spring14due to the deformation of the disk shaped spring14. When the operating fluid flows in the space, high damping force is generated, such that handling stability may be improved.

However, when the large impact is applied to the damper, that is, when the pressure of the operating fluid larger than the force with which the dish shaped spring22presses the washer23is transferred to the body valve assembly, the disk shaped spring14may be no longer deformed as seen inFIG. 6, such that deformation of the dish shaped spring22is generated. The fastener by which the bolt31and the nut32are fastened to each other is relatively displaced downwardly with respect to the body valve body11due to the deformation of dish shaped spring22to form a space between the disk shaped spring14and a lower surface of the body valve body11, such that a channel area of the operating fluid may increase. Since the channel area increases, an increase amount in the damping force becomes smooth, such that the ride comfort may be improved.

If the damping force is generated only by the disk shaped spring14without the dish shaped spring22at the time of the compression stroke, when the large impact is applied to the vehicle, the damping force rapidly increases, such that the ride comfort may be deteriorated. However, in the present invention, since the damping force is generated using both of the dish shaped spring22and the disk shaped spring14at the time of the compression stroke, even though the operation of the damper changes from a low speed section to a high speed section, the damping force smoothly increases, such that the ride comfort may be improved.

Hereinafter, an operation of the impact sensitive damper according to the present invention configured as described above will be described in connection with the generation of the damping force at the time of the compression stroke.

A state view showing a flow of operating fluid formed in a body valve assembly of a damper at a low speed is shown inFIG. 4; and a state view showing a flow of operating fluid formed in a body valve assembly of a damper at a high speed is shown inFIG. 5.

As shown inFIG. 4, in a low speed operating section of the damper, the operating fluid passes through the compression channel16of the body valve body11and then flows through the slit15of the disk shaped spring14.

In the low speed operating section, the dish shaped spring22is not deformed and the disk shaped spring14may be slowly deformed. That is, the operating fluid flowing through the slit15at the beginning may flow in a space formed between the disk shaped spring14and the body valve body11as the disk shaped spring14is gradually deformed.

Here, it needs to be noted that the space formed between the disk shaped spring14and the body valve body11due to the deformation of the disk shaped spring14is significantly smaller than a space formed between the disk shaped spring14and the body valve body11due to relative displacement of the fastener in the high speed operating section of the damper and there is a large difference in the area in which the operating fluid may flow.

As shown inFIG. 5, in a high speed operating section of the damper, the operating fluid flows in a space formed between the disk shaped spring14and the body valve body11, such that a channel area may significantly increase, as compared to the low speed operating section of the damper.

A case in which the damper is in the high speed operating section indicates a case in which when the large impact is applied to the damper, pressure generated due to the flow of the operation fluid is larger than the force with which the dish shaped spring22presses the washer23. Here, when the dish shaped spring22comes down, the fastener by which the bolt31and the nut32are fastened to each other may be relatively displaced downwardly with respect to the body valve body11. Therefore, a space may be formed between the disk shaped spring14and the body valve body11.

Since a deformation amount of the disk shaped spring14is relatively smaller in the high speed operating section than in the low speed operating section, there is a risk that the damping force rapidly increases. However, when the dish shaped spring22is deformed to thereby relatively displace the fastener by which the bolt31and the nut32are fastened to each other with respect to the body valve body11, the channel area increases, such that an increase in the damping force significantly decreases.

With the impact sensitive damper according to the present invention as described above, when the damper is operated in the low speed operating section, the handling stability may increase, and when the large impact is instantaneously applied to the damper to thereby operate the damper in the high speed operating section, the damping force smoothly increases, such that the ride comfort may be improved.

In addition, the impact sensitive damper according to the present invention may be manufactured without significantly changing a structure of the damper according to the related art, such that a process of manufacturing the damper according to the related art may be used as it is.

With the present invention as described above, it is possible to provide the impact sensitive damper in which both of the dish-shaped spring and the disk-shaped spring are used in the body valve of the damper to achieve smooth improvement of the damping force at the time of conversion from the low speed operating section of the damper into the high speed operating section thereof, such that the handling stability and the improvement of ride comfort may be simultaneously achieved.

Therefore, with the present invention, the improvement of the handling stability may be achieved due to high damping force characteristics in the low speed operating section of the damper and the improvement of the ride comfort may be achieved due to low damping force characteristics in the high speed operating section of the damper.

The impact sensitive damper according to the present invention has been described with reference to the exemplary embodiment of the present invention. However, the present invention is not limited to the above-mentioned exemplary embodiment and drawings but may be variously modified and changed within the following claims by those skilled in the art to which the present invention pertains.