JP4885753B2 - Caster with hydraulic damper - Google Patents

Description

  The present invention does not depend on the mass of the supported body, and includes a hydraulic damper that exhibits a good vibration damping effect even on the supported bodies of various masses, and the hydraulic damper at a desired position. The present invention relates to a caster with a hydraulic damper that supports a supported body in a movable manner.

  As a conventional hydraulic damper used in, for example, a caster with a hydraulic damper, the piston is vibrated in the axial direction with respect to a cylinder having a constant inner diameter in the axial direction and filled with oil. Some have absorbed vibration energy by frictional resistance due to the viscosity of the material to obtain a vibration damping effect (for example, see Patent Document 1).

JP 2001-277809 A

  Hereinafter, the hydraulic damper disclosed in Patent Document 1 will be described with reference to FIG.

  FIG. 4 is a model diagram of a conventional hydraulic damper.

  In FIG. 4, 101 is a hydraulic damper main body. Reference numeral 102 denotes a cylindrical cylinder filled with oil 103, and has a constant inner wall diameter dc in the axial direction. Reference numeral 104 denotes a lid for substantially sealing the cylinder 102, and a hole through which the shaft portion 105b of the piston 105 is inserted is formed. The piston 105 is integrally formed with a sliding portion 105a that slides with a predetermined gap from the inner wall of the cylinder 102, a shaft portion 105b, and an end surface portion 105c to which a load of a supported body is applied.

  Reference numeral 106 denotes an elastic member such as a coil spring, which generates a reaction force against the load of the supported body applied to the end portion 105c. That is, in a state where the load of the supported body is applied to the end portion 105c, the elastic member 106 is compressed and is in a balanced state.

  Incidentally, it is known that the damping performance of such a hydraulic damper depends on the damping ratio (ζ).

  The damping ratio (ζ) is theoretically obtained from Equation 1 and Equation 2. In Equations 1 and 2, c is a viscous damping coefficient [Nsec / m], m is a mass [kg] of a supported body, k is a spring constant [N / m] of an elastic member, and μ is a viscosity coefficient of oil. [Pa sec], l is the piston thickness [m], dc is the cylinder inner wall diameter [m], and dp is the piston outer diameter [m].

  As is clear from Equation 1 and Equation 2, the value of the damping ratio (ζ) becomes small when a large (heavy) supported body is supported, and as a result, the damping performance deteriorates.

  Therefore, in the conventional hydraulic damper 101, a desired damping effect can be obtained only for a supported body having a limited and small range of mass, and for a supported body having a larger mass than that. In general, good damping performance could not be obtained.

  The present invention has been made in order to solve the above-described problems, and has a simple configuration, but does not depend on the mass of the supported body, and can be used for various masses of the supported body. It is an object of the present invention to provide a hydraulic damper that exhibits a damping effect and a caster with a hydraulic damper that includes the hydraulic damper at a desired position and supports a supported body in a movable manner.

  A hydraulic damper according to a first aspect of the present invention is a damper for blocking or attenuating a vibration shock applied to a supported body, and a cylinder filled with oil inside and a shaft inside the cylinder. A piston installed in a slidable direction and extending from the inside of the cylinder to the outside and having an end to which a load of the supported body is applied; and the piston applied to the end of the piston An elastic member for generating a reaction force against the load of the supported body, and the position of the piston in the cylinder in a state where the load of the supported body and the reaction force of the elastic member are balanced. First, the inner wall diameter of the cylinder is variable so as to set the sliding clearance between the inner wall of the cylinder and the piston so that the damping ratio (ζ) obtained from the above-described equations 1 and 2 is constant. It was characterized by that.

  A caster with a hydraulic damper according to a second aspect of the invention is characterized in that the hydraulic damper according to the first aspect is provided at a desired position.

  The present invention has the following effects due to the above configuration.

  According to the first aspect of the present invention, the inner wall diameter of the cylinder is varied so as to set the sliding clearance between the inner wall of the cylinder and the piston so that the damping ratio (ζ) is constant. A constant attenuation performance can be obtained without depending on the mass.

  According to the invention of claim 2, even if the floor surface is moved in a state where the supported body is supported by providing the caster with the hydraulic damper, that is, the caster having the vibration damping function, for example, the floor surface It is possible to suppress the transmission of the vibration shock applied by the unevenness to the supported body.

Embodiment 1 FIG.
Hereinafter, an embodiment of a hydraulic damper according to the present invention will be described with reference to the drawings.

FIG. 1 is a model diagram showing a main configuration of a hydraulic damper according to an embodiment of the present invention, and is a longitudinal sectional view when a supported body (not shown) having a mass m ₁ is supported. FIG. 2 is a model diagram showing a main configuration of a hydraulic damper according to an embodiment of the present invention, and is a longitudinal sectional view when a supported body (not shown) having a mass m ₂ is supported.

  1 and 2, reference numeral 1 denotes a hydraulic damper body. Reference numeral 2 denotes a cylindrical cylinder filled with oil 3 and has an inner wall 2a that tapers in the axial direction (Z direction in the figure). Reference numeral 4 denotes a lid for substantially sealing the cylinder 2, and a hole through which the shaft portion 5b of the piston 5 is inserted is formed. The piston 5 is integrally formed with a sliding portion 5a that slides with a predetermined gap from the inner wall 2a of the cylinder 2, a shaft portion 5b, and an end surface portion 5c to which a load of a supported body (not shown) is applied. It becomes.

Reference numeral 6 denotes an elastic member, which is a coil spring in this embodiment. The elastic member 6 is not limited to a coil spring but may be a disc spring or the like. The elastic member 6 generates a reaction force against the load of the supported body applied to the end portion 5c. That is, FIG. 1, in a state in which the support is supported in the mass m _1, by the end portion 5c mass m ₁ of the supported member is applied, the elastic member 6 made compression, the balanced state is there. Similarly, the state 2, the state in which the supported body is supported in the mass m _2, by weight m ₂ of the supported member is applied to the end portion 5c, the elastic member 6 made compression, which commensurate with It is in.

As is clear from FIG. 1 and FIG. 2, m ₁ <m ₂ , and in the suspended state, the position of the sliding portion 5a is lower in FIG. 2 than in FIG. 1 (Z direction side in the figure).

  Incidentally, it is known that the damping performance of such a hydraulic damper depends on the damping ratio (ζ).

  And theoretically, the damping ratio (ζ) is obtained from the above-described formulas 1 and 2.

  As is clear from Equations 1 and 2, the value of the damping ratio (ζ) decreases as the mass (m) increases. That is, when a large (heavy) supported body is supported, the damping ratio (ζ) becomes small under the condition that the spring constant (k) and the viscous damping coefficient (c) are constant. Attenuation performance deteriorates.

However, in the present embodiment, the sliding gap between the inner wall 2a and the sliding portion 5a is smaller in the state of FIG. 2 than in the state of FIG. Then, when the viscous damping coefficient (c) is obtained from dc ₁ and dp shown in FIG. ₁ and dc ₂ and dp shown in FIG. 2 from Expression 2, the viscous damping in FIG. 2 is obtained from the viscous damping coefficient (c) in FIG. The coefficient (c) is larger.

  That is, as is clear from Equation 1, the value of the damping ratio (ζ) decreases as the mass (m) of the supported body increases, but on the other hand, as the viscous damping coefficient (c) increases, Become bigger. Therefore, when FIG. 1 is compared with FIG. 2, the mass (m) of the supported body is larger in FIG. 2 than in FIG. 1, and the viscous damping coefficient (c) is larger in FIG. As a result, the damping ratio (ζ) can be set to the same value in FIGS.

  In the present embodiment, the inner wall 2a has a linear slope so as to be easily processed. However, in order to further improve the damping performance, it depends on the mass (m) of the supported body. First, it is desirable to vary the viscous damping coefficient (c) so that the damping ratio (ζ) is constant. In order to vary the viscous damping coefficient (c), the sliding gap between the inner wall 2a and the sliding portion 5a may be varied.

  That is, the position of the sliding portion 5a of the piston 5 is obtained from the mass (m) of the supported body and the spring constant (k) of the elastic member 6, and the inner wall diameter dc of the cylinder 2 at the position is calculated from Equation 1 and Equation 2. What is necessary is just to calculate backward and form.

  As described above, the first embodiment has been described. The gist of the present invention is that the inner wall 2a of the cylinder 2 and the sliding portion 5a of the piston 5 move as the piston 5 moves to the back side (Z direction in the figure) inside the cylinder 2. This is to change the inner wall diameter dc of the cylinder 2 so that the sliding gap of the cylinder 2 becomes small. Furthermore, the inner wall diameter dc of the cylinder 2 is made variable so that the damping ratio (ζ) is constant.

  Accordingly, the configuration of the present subject matter is not limited to the configuration of the first embodiment, and the design can be changed as appropriate.

  For example, the elastic member 6 may have a configuration provided between the end 5c and the lid 4, and the installation location is not limited. Further, it may be a compression spring or a tension spring. Furthermore, the reaction force of the load on the support may be generated by a compressible gas.

  Further, the inner wall diameter dc of the cylinder 2 may be varied discontinuously (stepped) instead of continuously varying.

  Further, the cylinder is not limited to a cylindrical cylinder, and may be a cylinder having a rectangular cross section.

  The configuration of the first embodiment has been described above, but the special effects achieved by the present invention will be summarized below.

  Furthermore, the inner wall diameter dc of the cylinder 2 is varied so as to set the sliding clearance between the inner wall 2a of the cylinder 2 and the sliding portion 5a of the piston 5 so that the damping ratio (ζ) is constant. A constant damping performance can be obtained without depending on the mass of the support. As a result, the mass width of the supported support can be increased.

Embodiment 2. FIG.
Hereinafter, other embodiments according to the present invention will be described with reference to the drawings.

  FIG. 3 is a model diagram of a caster with a hydraulic damper including the hydraulic damper according to the first embodiment.

  Since the caster provided with the hydraulic damper as shown in FIG. 3 is a known technique, description of its configuration and function is omitted. The feature of this embodiment is that the hydraulic damper shown in the first embodiment is provided instead of the conventional hydraulic damper in which the sliding gap between the cylinder and the piston is constant.

  By adopting such a configuration, the caster 7 is provided with the hydraulic damper 1, that is, the caster 1 is provided with a vibration damping function, so that the floor surface can be moved while the supported body 8 is supported. For example, it is possible to suppress the vibration impact applied by the unevenness of the floor surface from being transmitted to the supported body 8. And the mass width of the to-be-supported to-be-supported body 8 spreads.

  In the configuration in which the caster 7 includes the hydraulic damper 1 as in the second embodiment, the damping ratio (ζ) in the hydraulic damper is a vibration frequency that can be applied when the caster 7 on the normal floor is moved. In consideration of the band, the damping ratio (ζ) is preferably 0.6.

A model diagram showing a configuration of a main part of a hydraulic damper according to an embodiment of the present invention, is a longitudinal sectional view when supporting the supported body mass m ₁ (not shown). A model diagram showing a configuration of a main part of a hydraulic damper according to an embodiment of the present invention, is a longitudinal sectional view when supporting the supported body mass m ₂ (not shown). It is a model figure of the caster with a hydraulic damper provided with the hydraulic damper which concerns on Embodiment 1. FIG. It is a model figure of the conventional hydraulic damper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydraulic damper 2 Cylinder 3 Oil 5 Piston 5c End part of piston 6 Elastic member 7 Caster with hydraulic damper 8 Supported body dc Inner wall diameter of cylinder

Claims (1)

A hydraulic damper comprising a hydraulic damper for blocking or attenuating a vibration impact applied to a supported body , wherein the hydraulic damper is provided at a desired position, and the supported body is movably supported with respect to a floor surface. With casters ,
The hydraulic damper is
A cylinder filled with oil inside,
A piston installed inside the cylinder so as to be slidable in the axial direction, and extending from the inside of the cylinder to the outside, and having an end to which a load of the supported body is applied;
An elastic member for generating a reaction force against the load of the supported body applied to the end of the piston;
Comprising
Regardless of the position of the piston inside the cylinder in a state where the load of the supported body and the reaction force of the elastic member are balanced, the vibration frequency band that can be applied when the caster on the floor is moved is taken into consideration do it,
The hydraulic damper is characterized in that the inner wall diameter of the cylinder is varied so as to set the sliding clearance between the inner wall of the cylinder and the piston so that the damping ratio (ζ) obtained from Equation 1 is constant. Caster with.

Here, c is a viscous damping coefficient [Nsec / m], m is a mass [Kg] of the supported body, k is a spring constant [N / m] of the elastic member, and c is obtained by the following equation.

Here, μ is the oil viscosity coefficient [Pa sec], l is the piston thickness [m], dc is the cylinder inner wall diameter [m], and dp is the piston outer diameter [m].

Images