JP2020106107A - Damper - Google Patents

Abstract

To provide a damper capable of suppressing suction of air while providing a rod guide.SOLUTION: A damper includes: a cylinder 3 having a working chamber 13 filled with oil L; a piston 5 movably disposed in the working chamber 13 of the cylinder 3; a piston rod 7 extended from the piston 5 to outside of the cylinder 3 and moved axially to cause the piston 5 to cooperate; a rod guide 9 disposed around the piston rod 7 and causing the piston rod 7 to slide on an inner peripheral surface 9a for guiding; an accumulator 25 provided on the outer periphery of the rod guide 9 and communicated with the working chamber 13 to absorb a volumetric change in the working chamber 13 corresponding to pushing of the piston rod 7 into the cylinder 3; and a seal member 11 disposed adjacent to the rod guide 9 and sealing the circumference of the piston rod 7. The rod guide 9 includes an opening part 9i causing the accumulator 25 to face the seal member 11.SELECTED DRAWING: Figure 3

Description

The present invention relates to a damper that moves a piston in a cylinder to generate a damping force.

As a conventional damper, for example, as in Patent Document 1, a piston is axially movable in a working chamber of a cylinder in which oil as a working fluid is enclosed, and a piston rod is extended from the piston to the outside of the cylinder. There is something.

In this damper, when the piston rod is pushed into the cylinder, the piston is interlocked to generate a damping force. The damper may be provided with a rod guide in order to guide the piston rod at this time and ensure stability of operation.

The rod guide is arranged adjacent to the working chamber around the piston rod, and guides the piston rod by slidingly contacting the piston rod with the inner peripheral surface. A seal member is arranged adjacent to the rod guide, and oil extends from the working chamber to the seal member through a gap between the rod guide and the piston rod. Thus, the guide of the piston/rod can be made smooth.

However, in such a structure, when the piston rod is pushed into the cylinder, the oil between the seal member and the rod guide enters the working chamber of the cylinder through the gap between the rod guide and the piston rod. And will move.

For this reason, there is a problem that the pressure between the seal member and the rod guide is reduced and air is sucked from the outside. This intake of air lowers the response of the generation of the damping force to the movement of the piston rod, and therefore needs to be suppressed.

JP 2006-10001 A

The problem to be solved is that if a rod guide is provided, air will be sucked in.

A first aspect of the present invention is to provide a cylinder having a working chamber that contains a working fluid and a piston that is movably arranged in the working chamber of the cylinder, in order to suppress intake of air while providing a rod guide. And a piston rod that is pulled out from the piston to the outside of the cylinder to interlock the piston by moving in the axial direction, and a piston rod that is arranged around the piston rod and slides the piston rod on the inner peripheral surface. A rod guide for guiding, and an accumulator provided on the outer periphery of the rod guide and communicating with the working chamber to absorb a volume change in the working chamber according to pushing of the piston rod into the cylinder. A seal member disposed on the opposite side of the working chamber adjacent to the rod guide to seal the circumference of the piston rod, the rod guide opening the accumulator to the seal member. The feature of the damper is that it has a part.

A second aspect of the present invention is a cylinder having a working chamber containing a working fluid, a piston movably arranged in the working chamber of the cylinder, and an axial direction that is drawn from the piston to the outside of the cylinder. Provided on the outer circumference of the rod guide, a piston rod for interlocking the piston by the movement of the rod guide, a rod guide arranged around the piston rod for guiding the piston rod by sliding on the inner peripheral surface, An accumulator that communicates with the working chamber and absorbs a volume change in the working chamber in response to the pushing of the piston rod into the cylinder; and an accumulator adjacent to the rod guide on the opposite side to the working chamber. A seal member arranged to seal the periphery of the piston rod, wherein the rod guide is provided on the inner peripheral surface so as to enlarge a gap between the piston rod and the piston rod along the axial direction. A characteristic of the damper is that it has a groove formed therein.

In the first aspect of the present invention, when the piston rod is pushed into the cylinder, even if the working fluid between the seal member and the rod guide moves into the working chamber of the cylinder, the accumulator acts as a seal member. The working fluid can be replenished in the gap between the rod guide. Therefore, it is possible to suppress the pressure decrease in the gap between the seal member and the rod guide, and to suppress the intake of air.

In the second aspect of the present invention, when the piston rod is pushed into the cylinder, it is possible to prevent the working fluid between the seal member and the rod guide from moving into the working chamber of the cylinder. Therefore, it is possible to suppress a decrease in pressure between the seal member and the rod guide, and suppress intake of air.

It is sectional drawing of a damper (Example 1). It is an expanded sectional view which shows the rod guide periphery of the damper of FIG. 1 (Example 1). It is an expanded sectional view of the area|region III of FIG. 1 (Example 1). It is sectional drawing which shows the rod guide of the damper of FIG. 1 (Example 1). It is a top view of the rod guide of FIG. 4 (Example 1). It is a bottom view of the rod guide of FIG. 4 (Example 1). It is an expanded sectional view which shows the rod guide periphery of a damper (Example 2). 8 is a bottom view of the rod guide of FIG. 7 (Example 2). FIG. It is sectional drawing of a damper (Example 3).

For the purpose of suppressing air intake while providing the rod guide, the rod guide is provided with an opening for exposing the accumulator on the outer periphery of the rod guide to the seal member, or on the inner peripheral surface of the rod guide. This was achieved by providing a groove so as to widen the gap between the piston and the rod along the axial direction.

A configuration may be adopted in which a gap larger than the gap between the piston rod and the inner peripheral surface of the rod guide is provided between the piston rod and the seal member.

The rod guide may integrally have a circumferential wall portion projecting to the seal member side, and the seal member may be housed in the inner periphery of the wall portion of the rod guide.

The seal member may be a U packing having a U-shaped cross section.

1 is a cross-sectional view of a damper according to a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view showing the vicinity of a rod guide of the damper of FIG.

As shown in FIGS. 1 and 2, the damper 1 generates a damping force at the time of contraction operation in the axial direction, and includes a cylinder 3, a piston 5, a piston rod 7, a rod guide 9, and a seal member. 11 and. In the following, the axial direction means the axial direction of the damper 1, and the radial direction means the radial direction of the damper 1.

The cylinder 3 is made of resin such as polyacetal, and has a cylindrical shape with one end closed and the other end open. The material of the cylinder 3 is not particularly limited and may be formed of metal or the like.

Inside the cylinder 3, a working chamber 13 containing an oil L as a working fluid is defined at one end side. A guide accommodating chamber 15 for accommodating the rod guide 9 having a diameter larger than that of the working chamber 13 is formed at the other end of the cylinder 3. Between the working chamber 13 and the guide accommodating chamber 15, a stepped portion 17 for positioning the outer edge of the end of the rod guide 9 is provided.

The piston 5 is arranged in the working chamber 13 of the cylinder 3 so as to be movable in the axial direction. The piston 5 of this embodiment is made of resin such as polyacetal and is formed in a columnar shape.

The piston 5 partitions the working chamber 13 of the cylinder 3 into a pressure chamber 13a and a non-pressure chamber 13b. The piston 5 is provided with a plurality of circulation paths 5a in the circumferential direction. The return path 5a penetrates the piston 5 in the axial direction and allows the pressure chamber 13a and the non-pressure chamber 13b to communicate with each other.

The piston 5 is attached to the tip of the piston rod 7 on the non-pressure chamber 13b side. A protrusion 5c is integrally provided on the surface 5b of the piston 5 on the pressure chamber 13a side. A disk-shaped valve body 5e is supported on the protrusion 5c so as to be movable in the axial direction.

The piston 5 is adapted to generate a damping force by moving toward the one end side of the cylinder 3. Specifically, the pressure of the oil L causes the valve body 5e to come into contact with the surface 5b of the piston 5 to close the return passage 5a, and the pressure between the inner peripheral surface of the cylinder 3 and the outer peripheral surface of the piston 5 as a flow path. A damping force is generated by moving the oil L from the chamber 13a to the non-pressure chamber 13b.

On the other hand, when the piston 5 moves toward the other end, the valve body 5e separates from the surface 5b of the piston 5 and opens the return passage 5a. This allows the piston 5 to move smoothly toward the other end of the cylinder 3.

Contrary to the above, the damping force may be generated when the piston 5 moves to the other end side, or when the piston 5 moves to both the one end side and the other end side.

The piston rod 7 is a rod made of metal such as stainless steel. The piston rod 7 extends axially from the piston 5 to the other end side of the cylinder 3 and is drawn out of the cylinder 3. A rod cap 19 made of resin such as polyacetal is attached to the outer end of the piston rod 7.

The piston rod 7 expands and contracts with respect to the cylinder 3 (by moving in the axial direction) to interlock the piston 5. The expansion/contraction movement of the piston rod 7 is guided by the rod guide 9.

3 is an enlarged sectional view of a region III in FIG. 2, FIG. 4 is a sectional view showing the rod guide 9, FIG. 5 is a plan view of the same, and FIG. 6 is a bottom view of the same.

As shown in FIGS. 1 to 6, the rod guide 9 is arranged around the piston rod 7, and guides the piston rod 7 by sliding the piston rod 7 on the inner peripheral surface 9a. Specifically, the rod guide 9 is formed in a cylindrical shape, and an insertion hole 9b through which the piston rod 7 is inserted is defined by an inner peripheral surface 9a in the axial center portion. Although the rod guide 9 is made of resin such as polyacetal, it may be made of other material.

The rod guide 9 is fitted in the guide accommodating chamber 15 of the cylinder 3. One end of the rod guide 9 has its outer edge abutted against the step portion 17 between the working chamber 13 and the guide accommodating chamber 15, and the other end thereof abuts a cap 21 attached to the other end of the cylinder 3. Have been locked out. The cap 21 is made of resin such as polyacetal and is fixed to the other end of the cylinder 3 by caulking or the like.

On the outer circumferences of one end and the other end of the rod guide 9, annular projections 9ca and 9cb are integrally provided. The outer diameters of the annular protrusions 9ca and 9cb are formed to be substantially the same as the inner diameter of the guide accommodating chamber 15. Therefore, the outer peripheral surfaces of the annular convex portions 9ca and 9cb are fitted to the inner peripheral surface of the guide accommodating chamber 15.

An intermediate portion 9d between the annular protrusions 9ca and 9cb of the rod guide 9 is formed in a radial concave shape relative to the annular protrusions 9ca and 9cb. Further, the annular convex portions 9ca, 9cb are formed with support concave portions 9ea, 9eb in the radial direction. The membrane 23 is supported by the support recesses 9ea and 9eb, whereby an accumulator 25 is formed on the outer circumference of the rod guide 9.

A plurality of through holes 9f (three in the embodiment) are formed in the annular convex portion 9ca on the one end side of the rod guide 9 so as to penetrate in the axial direction. The through hole 9f communicates the accumulator 25 with the working chamber 13 and allows the oil L to flow between the accumulator 25 and the working chamber 13.

An annular projection 9cb on the other end side of the rod guide 9 is integrally provided with a circumferential wall 9g protruding toward the seal member 11 side. The wall portion 9g is formed along the inner peripheral surface of the peripheral wall 21a of the cap 21. The seal member 11 is fitted and accommodated in the inner circumference of the wall 9g. The wall portion 9g can be omitted.

Further, the annular convex portion 9cb is provided with a concave portion 9h which is provided adjacent to the seal member 11 and which enlarges a gap d1 between the rod guide 9 and the seal member 11. As a result, the gap d1 between the rod guide 9 and the seal member 11 is larger than the gap d2 between the piston rod 7 and the inner peripheral surface 9a of the rod guide 9. The recess 9h can be omitted.

Further, the annular convex portion 9cb has an opening 9i that allows the accumulator 25 to face the seal member 11. The opening 9i is provided so as to axially penetrate the annular projection 9cb at one location in the circumferential direction, and connects the accumulator 25 with the gap d1 between the seal member 11 and the rod guide 9. In this embodiment, the opening 9i communicates the recess 9h of the rod guide 9 with the accumulator 25.

It is also possible to provide a plurality of openings 9i in the circumferential direction. However, in order not to impair the function of the accumulator 25, the flow rate of the oil L flowing out from the accumulator 25 in the opening 9i is smaller than the flow rate of the oil L flowing into the accumulator 25 through the through hole 9f. Set.

The accumulator 25 can absorb the volume change in the working chamber 13 of the cylinder 3 due to the expansion and contraction of the piston rod 7. Specifically, the excess oil L is accommodated according to the pushing of the piston rod 7 into the cylinder 3. The accumulator 25 of this embodiment is formed by covering the concave intermediate portion 9d of the rod guide 9 with the membrane 23.

The membrane 23 is made of an elastic material such as rubber and is formed as a tubular elastic film. The membrane 23 is arranged along the outer peripheral surface of the rod guide 9. Both ends of the membrane 23 are gradually expanded in diameter in accordance with the annular protrusions 9ca and 9cb.

Circumferential projections 23a and 23b are provided on both ends of the membrane 23 along the inner circumference, and the projections 23a and 23b are supported by fitting in the support recesses 9ea and 9eb of the annular projections 9ca and 9cb. Has been done. In this state, both ends of the membrane 23 are sandwiched between the annular convex portion 9ca and the cylinder 3, and also serve to seal between the cylinder 3 and the rod guide 9.

The seal member 11 is arranged adjacent to the rod guide 9 on the side opposite to the working chamber 13 and seals the periphery of the piston rod 7. The seal member 11 is made of an elastic material such as nitrile rubber and is a U packing having a U-shaped cross section in this embodiment. As the seal member 11, it is possible to adopt a seal member having a shape other than the U packing.

The seal member 11, which is a U-packing, has a circumferential groove 11a, and both sides of the circumferential groove 11a in cross section contact the inner circumferential surface of the wall portion 9g of the rod guide 9 and the outer circumferential surface of the piston rod 7.

[Damper operation]
When an impact is input to the rod cap 19 of the piston rod 7, the damper 1 moves and is pushed so that the piston rod 7 contracts with respect to the cylinder 3. In response to this, the piston 5 moves in the working chamber 13 toward the one end side of the cylinder 3 to generate a damping force.

At this time, the volume of the working chamber 13 decreases according to the pushing amount of the piston rod 7, but the excess oil L in the working chamber 13 flows into the accumulator 25 accordingly. The oil L flowing into the accumulator 25 elastically deforms the membrane 23, and as a result, the volume decrease in the working chamber 13 is absorbed.

When the piston rod 7 is pushed in, the oil L in the gap d1 between the seal member 11 and the rod guide 9 moves between the piston rod 7 and the rod guide 9 in accordance with the movement of the piston rod 7. Via the gap d2 of the above, it moves into the working chamber 13 and decreases (arrow in FIG. 3).

At this time, in this embodiment, the oil L in the accumulator 25 flows into the gap d1 through the opening 9i, so that the oil L is replenished in the gap d1 (arrow in FIG. 3). For this reason, in the gap d1, the pressure drop is suppressed, and the suction of air when the piston rod 7 is pushed is suppressed.

[Effect of Example 1]
The damper 1 of the present embodiment includes a cylinder 3 having a working chamber 13 containing oil as a working fluid, a piston 5 movably arranged in the working chamber 13 of the cylinder 3, and a piston 5 to the outside of the cylinder 3. And a piston rod 7 which is pulled out to interlock the piston 5 by moving in the axial direction, and a rod guide 9 which is arranged around the piston rod 7 and slides and guides the piston rod 7 on an inner peripheral surface 9a. , An accumulator 25 which is provided on the outer periphery of the rod guide 9 and communicates with the working chamber 13 to store the oil L in response to the pushing of the piston rod 7 into the cylinder 3, and a rod on the opposite side to the working chamber 13. A seal member 11 arranged adjacent to the guide 9 and sealing the periphery of the piston rod 7. The rod guide 9 has an opening 9 i that allows the accumulator 25 to face the seal member 11.

Therefore, in the damper 1 of this embodiment, when the piston rod 7 is pushed into the cylinder 3, the oil L in the gap d1 between the seal member 11 and the rod guide 9 moves into the working chamber 13 of the cylinder 3. However, the oil L can be replenished from the accumulator 25 to the gap d1.

Therefore, it is possible to suppress a decrease in pressure in the gap d1 between the seal member 11 and the rod guide 9, and to suppress intake of air while providing the rod guide 9.

Further, in the damper 1 of the present embodiment, the rod guide 9 integrally has a circumferential wall portion 9g, and the seal member 11 is housed inside the wall portion 9g of the rod guide 9.

Therefore, in this embodiment, the seal member 11 can be securely held, and the size can be reduced as compared with the case where the seal member 11 is held between the inner peripheral surface of the cylinder 3 and the piston rod 7. In such a configuration, although the distance between the seal member 11 and the rod guide 9 becomes short, the intake of air can be reliably suppressed as described above.

Further, in the present embodiment, even if the seal member 11 is a U packing having a U-shaped cross section, it is possible to easily and reliably suppress the intake of air, and it is possible to reduce the cost and simplify the structure.

7 is a cross-sectional view showing the vicinity of the rod guide of the damper according to the second embodiment of the present invention, and FIG. 8 is a bottom view of the rod guide of FIG. In addition, in the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

Instead of the opening 9i of the first embodiment, the damper 1 of the second embodiment has a groove portion that expands the gap d2 between the piston rod 7 and the inner peripheral surface 9a of the rod guide 9 along the axial direction. 9j is provided. Others are the same as those in the first embodiment.

That is, in the rod guide 9 of the second embodiment, the annular projection 9cb is not provided with the opening 9i of the first embodiment, and the accumulator 25 is provided in the gap d1 between the rod guide 9 and the seal member 11. It has not come.

Instead of this, the rod guide 9 is provided with the groove portion 9j on the inner peripheral surface 9a as described above. The groove 9j extends over the entire inner peripheral surface 9a of the rod guide 9 in the axial direction. Two groove portions 9j of this embodiment are provided in the circumferential direction. However, it is also possible to provide a single or three or more groove portions 9j.

With such a configuration, in the damper 1 of this embodiment, when the piston rod 7 is pushed into the cylinder 3, the oil L in the gap d1 between the seal member 11 and the rod guide 9 causes the working chamber 13 of the cylinder 3 to move. It is possible to suppress the movement of the inside of the gap d1 and to suppress the decrease of the pressure in the gap d1. As a result, the damper 1 of the present embodiment can also achieve the same effects as the first embodiment.

FIG. 9 is a sectional view of a damper according to the third embodiment of the present invention. In the third embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the duplicate description will be omitted.

The damper 1 of the present embodiment is one in which the accumulator 25 is formed of a stretchable member.

The accumulator 25 of this embodiment is formed in a tubular shape made of independent foam rubber, and is wound around the outer periphery of the intermediate portion 9d of the rod guide 9. The accumulator 25 can absorb the volume change in the working chamber 13 by expansion and contraction.

Further, the accumulator 25 defines a gap d3 between the inner peripheral surface of the cylinder 1 and the annular convex portions 9ca and 9cb of the rod guide 9. The oil L in the working chamber 13 can flow into the space between the seal member 11 and the rod guide 9 through the accumulator 25 through the gap d3.

The rod guide 9 holds a seal member 29 such as an O-ring on the annular convex portion 9cb and is sealed between the rod guide 9 and the cylinder 1.

Also in this embodiment, it is possible to obtain the same effects as those of the first embodiment. The accumulator 25 of this embodiment can be applied to the second embodiment.

1 Damper 3 Cylinder 5 Piston 7 Piston Rod 9 Rod Guide 9a Rod Guide Inner Surface 9j Groove 11 Seal Member 13 Working Chamber 25 Accumulator d1 Gap (Between Rod Guide and Seal Member)
d2 clearance (between rod/guide and piston/rod)

Claims (4)

A cylinder having a working chamber containing a working fluid,
A piston movably arranged in the working chamber of the cylinder;
A piston rod that is pulled out from the piston to the outside of the cylinder to move the piston in an axial direction, and
A rod guide that is arranged around the piston rod and slides and guides the piston rod on the inner peripheral surface;
An accumulator provided on the outer periphery of the rod guide and communicating with the working chamber to absorb a volume change in the working chamber according to pushing of the piston rod into the cylinder;
A seal member disposed on the opposite side of the working chamber and adjacent to the rod guide to seal around the piston rod,
The rod guide has an opening that exposes the accumulator to the seal member,
A damper characterized by that. A cylinder having a working chamber containing a working fluid,
A piston movably arranged in the working chamber of the cylinder;
A piston rod that is pulled out from the piston to the outside of the cylinder to move the piston in an axial direction, and
A rod guide that is arranged around the piston rod and slides and guides the piston rod on the inner peripheral surface;
An accumulator provided on the outer periphery of the rod guide and communicating with the working chamber to absorb a volume change in the working chamber according to pushing of the piston rod into the cylinder;
A seal member disposed on the opposite side of the working chamber and adjacent to the rod guide to seal around the piston rod,
The rod guide has a groove portion provided on the inner peripheral surface so as to enlarge a gap between the rod guide and the piston rod along the axial direction.
A damper characterized by that. The damper according to claim 1 or 2, wherein
The rod guide integrally has a circular wall portion,
The seal member is housed in the inner periphery of the wall portion of the rod guide,
A damper characterized by that. The damper according to any one of claims 1 to 3,
The seal member is a U packing having a U-shaped cross section,
A damper characterized by that.

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