JP2008223797A - Gas spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas spring short in its total length, and simple in the manufacturing process, in a gas spring having a bellows. <P>SOLUTION: The metallic bellows substantially coaxially arranged with a cylinder are arranged between an outer cylinder and the cylinder. A bellows inner chamber partitioned by the inside of the bellows and the outside of the cylinder, is communicated with a cylinder chamber partitioned by the cylinder, a piston and a rod side plate, to be formed as an oil chamber of filling a hydraulic fluid inside, and the gas spring is also constituted with a bellows outer chamber as a high pressure gas chamber sealed with gas of predetermined pressure. Thus, the gas spring capable of applying pressure by the bellows, shortening the total length and easy in manufacture, can be provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas spring suitable for applications in which tension is applied to tension lines such as railway overhead lines (train lines) and power transmission lines.

A gas spring for combining a gas chamber and a piston cylinder mechanism to apply a predetermined tension to a railway overhead line or the like is known. For example, a gas spring described in Japanese Patent Application Laid-Open No. 2001-20987 is formed by forming a metal bellows inside a high-pressure gas chamber and the metal bellows outside as an oil chamber, and connecting the cylinder bellows to the cylinder oil chamber. The piston is actuated so that the hydraulic oil presses the high pressure gas chamber, and a predetermined tension is applied to the overhead wire via the rod. Such a gas spring is generally preferable because it has a feature that an initial load is higher than that of a coil spring and a spring constant can be lowered. In addition, the metal bellows used for gas / oil separation membranes in gas springs has high durability and high-frequency response compared to rubber bladders and free pistons. As best.
JP 2001-20987 A

  However, the conventional method of using the metal bellows is a structure in which one end of the metal bellows is fixed and the other end is stretchably and airtightly closed. Therefore, the expansion / contraction free end of the metal bellows cannot be fixed, and when the cylinder is built in the metal bellows, there is a problem that the cylinder end cannot be fixed and a lateral load cannot be received, and the metal bellows is connected in series at the rear of the cylinder. In the case of the structure connected to the gas spring, there is a problem that the total length of the gas spring becomes long.

  In such a structure, the low pressure gas chamber defined by the cylinder bottom and the piston is not in contact with the outer cylinder, and the passage leading to the low pressure gas chamber cannot be directly opened in the outer cylinder. The rear cylinder had to be assembled to the outer cylinder, and the process was slightly complicated in producing the gas spring.

  It is an object of the present invention to provide a gas spring having a bellows that can be shortened in overall length and simple in manufacturing process.

  In order to solve the above problems, the present invention has a gas spring configured as follows.

1. A piston, a cylinder in which the piston is slidably provided inside, an outer cylinder provided on the outer periphery of the cylinder substantially coaxially with the cylinder, and the cylinder between the outer cylinder and the cylinder A metal bellows provided substantially coaxially with the cylinder, and a cylinder bottom plate for attaching and closing the cylinder and airtightly closing and fixing one end in the axial direction of the bellows and the outer cylinder, and attaching the cylinder, and A rod side plate that hermetically closes and fixes the other end in the axial direction of the bellows and the outer cylinder, and slidably penetrates the rod fixed to the piston;
One of a bellows inner chamber defined by the inside of the bellows and the outside of the cylinder, or a bellows outer chamber defined by the outside of the bellows and the inside of the outer cylinder, the cylinder, the piston, and the rod side plate And an oil chamber filled with working oil inside the bellows inner chamber or the bellows outer chamber communicated with the cylinder chamber, and the cylinder chamber,
Further, one of the bellows inner chamber or the bellows outer chamber that is not communicated with the cylinder chamber is configured as a high-pressure gas chamber in which a gas having a predetermined pressure is sealed.

  2 and 1, the bellows is assembled between the cylinder and the outer cylinder in a state where the bellows is compressed in the axial direction in advance. In other words, the number of peaks and valleys was increased, and the intervals between the peaks and valleys were narrowed beforehand.

  In the gas spring according to 3, 1 or 2, the bellows has an inner diameter side edge and an outer diameter side edge bent sharply, and the abdomen is formed in a wave-like unevenness.

  In the gas spring according to any one of 4, 1 to 3, a predetermined amount of liquid is stored in the high-pressure gas chamber.

  In the gas spring according to any one of 5, 1-4, the piston chamber defined by the cylinder, the piston, and the cylinder side plate is a low pressure gas chamber set to an internal pressure lower than an internal pressure of the high pressure gas chamber, The dried inert gas was sealed in the low-pressure gas chamber.

  6. The gas spring according to any one of claims 1 to 5, wherein one of the outer cylinder and the rod is connected to a tension line such as a train line or a power transmission line, and the other of the outer cylinder and the rod is a tension line support member. The rod is drawn into the cylinder by the pressure of the high pressure gas chamber to give a predetermined tensile force to the tension line, and the high pressure gas is constant regardless of temperature fluctuations. The chamber was set to a predetermined volume.

  In the gas spring of the present invention, a bellows is provided on the outer periphery of the cylinder, and the operating range of the piston and the bellows can be arranged substantially coaxially, so that the overall length can be shortened and the size can be reduced. Since both the high-pressure gas chamber and the low-pressure gas chamber can have communication holes formed outside the gas spring, each gas can be easily sealed in the gas chamber, and the manufacturing process is simplified.

  By compressing and mounting the bellows in the axial direction, the operating range of the bellows can be increased, and the movable range of the gas spring can be expanded. Since the bellows of the bellows is formed with wave-like irregularities, the bellows can be greatly changed from the expanded state to the contracted state, the change in volume can be increased, and the gas spring can be provided with a small size and a wide range of application. . Since a liquid such as oil is sealed in the high-pressure gas chamber, the volume of the high-pressure gas chamber can be set arbitrarily, and the bellows can be operated smoothly. Since the volume of the high-pressure gas chamber is set to a predetermined volume where the tension is constant, the tension line can always be pulled with a constant tension regardless of the temperature change.

  An embodiment of a gas spring according to the present invention will be described.

  FIG. 1 shows a gas spring 10. The gas spring 10 is provided in the outer cylinder 12, a bellows cylinder 14 provided on the inner peripheral side of the outer cylinder 12, a cylinder 16 provided on the inner peripheral side of the bellows cylinder 14, and the cylinder 16. A piston 18, a rod 20 attached to the piston 18, a cylinder bottom plate 22 that closes the bottom of the cylinder 16, a rod side plate 24 provided on the opposite side of the cylinder bottom plate 22, a rod cover 25 that covers the rod 20, and the like. Has been.

  The outer cylinder 12 is cylindrical, and a cylinder bottom plate 22 is airtightly fixed to the right end (right side in the figure) of the outer cylinder 12, and a rod side plate 24 is airtightly fixed to the left end.

  The bellows cylinder 14 is a cylindrical body made of a thin metal plate and is concentrically attached between the outer cylinder 12 and the cylinder 16, and the right end (right side in the figure) of the bellows cylinder 14 is airtight to the cylinder bottom plate 22. The left end is airtightly fixed to the rod side plate 24. The bellows cylinder 14 has a bellows shape in which crests and troughs expanded in the radial direction are alternately formed in the axial direction, for example, austenitic stainless steel having a plate thickness of about 0.1 mm to 0.3 mm. This is an integrally formed bellows that is formed into a bellows shape by plastic processing of a thin metal plate.

  The bellows cylinder 14 basically does not expand or contract in the radial direction, and the axial direction is fixed to the cylinder bottom plate 22 and the rod side plate 24, respectively. The interval between the inclined surfaces of the bellows cylinder 14 changes appropriately depending on the pressure difference generated inside and outside of the bellows cylinder 14, and functions as a bellows that changes the volume of the inside and outside. A space formed between the outer cylinder 12 and the bellows cylinder 14 is referred to as a bellows outer chamber 13.

  On the outer surface side of the bellows cylinder 14, in order to prevent the bellows cylinder 14 from being worn or damaged due to the bellows cylinder 14 coming into contact with the inner surface of the outer cylinder 12, there is little frictional resistance and excellent wear resistance. A guide 37 made of synthetic resin is provided. Similarly, on the inner surface side of the bellows cylinder 14, the bellows cylinder 14 has less frictional resistance and wear resistance in order to prevent the bellows cylinder 14 from being worn or damaged due to contact with the outer surface of the cylinder 16. A guide 39 made of a synthetic resin having excellent properties is provided. The guide 39 is attached as necessary.

  The cylinder 16 is provided on the inner side of the bellows cylinder 14 so as to be substantially coaxial with the outer cylinder 12 and concentrically. The right end (right side in the figure) of the cylinder 16 is airtightly fixed to the cylinder bottom plate 22, and the left end is airtightly fixed to the rod side plate 24. A piston 18 is provided inside the cylinder 16 so as to be slidable in the axial direction. A space formed between the bellows cylinder 14 and the cylinder 16 is referred to as a bellows inner chamber 15.

  The piston 18 has a gas seal 19 on the cylinder bottom plate 22 side on the outer peripheral surface, a piston seal 21 on the rod side plate 24, and a piston bearing 23 between the gas seal 19 and the piston seal 21. On the other hand, it is kept airtight and liquid tight, and is movable in a state where sliding resistance is low.

  A rod 20 is integrally fixed to the piston 18. The rod 20 penetrates the rod side plate 24 and moves in the axial direction together with the piston 18. A seal housing 27 is attached to the rod side plate 24, and the seal housing 27 is liquid-tightly fixed to the rod side plate 24 via a housing seal 29 provided on the outer periphery of the seal housing 27. In the seal housing 27, a rod hole 30 is formed at the center, and a dust seal 31, a rod seal 32, and a rod bearing 33 attached to the inner peripheral surface of the rod hole 30 are assembled to the outer periphery of the rod 20. Thus, the rod 20 is liquid-tightly and slidably held by the seal housing 27, that is, the rod side plate 24. A fitting 28 is provided at the end of the rod 20, and faces the fitting 26 provided on the cylinder bottom plate 22 in the axial direction. A rod cover 25 is attached to the rod 20 so as to cover the outer cylinder 12.

  The inside of the cylinder 16 is partitioned by a piston 18, and a portion of the cylinder 16 partitioned by the piston 18 and the rod side plate 24 is a cylinder chamber 34, and a portion partitioned by the piston 18 and the cylinder bottom plate 22 is a piston. This is the chamber 35.

  Further, a communication hole 36 is formed in the end portion of the cylinder 16 on the rod side plate 24 side, and the cylinder chamber 34 and the bellows inner chamber 15 are communicated with each other. The communication hole 36 is provided outside the operating range of the piston 18, and the piston 18 and the communication hole 36 do not overlap even when the piston 18 reaches the stop point on the rod side plate 24 side. The cylinder chamber 34 and the bellows inner chamber 15 are filled with hydraulic oil to form an oil chamber.

  Further, a communication hole 40 communicating with the bellows outer chamber 13 and a communication hole 41 communicating with the piston chamber 35 are formed in the cylinder bottom plate 22. Closing plugs 42 and 43 are attached to the communication hole 40 and the communication hole 41, respectively, and after a predetermined gas is sealed in the bellows outer chamber 13 and the piston chamber 35, the inside of the bellows outer chamber 13 and the piston chamber 35. Is sealed. The bellows outer chamber 13 is filled with an inert gas at a predetermined pressure, and the bellows outer chamber 13 is formed as a high-pressure gas chamber. The piston chamber 35 is filled with an inert gas such as dry nitrogen gas at a pressure of about atmospheric pressure in order to prevent rusting inside the piston chamber 35, and the piston chamber 35 is a low-pressure gas chamber. Is formed. At least the high pressure gas chamber is set to a pressure higher than a value obtained by (maximum pressure of the low pressure gas chamber) * (pressure receiving area of the piston) / (pressure receiving area of the piston on the rod side).

  Further, if necessary, an appropriate amount is added to the bellows outer chamber 13 as the high-pressure gas chamber in order to adjust the substantial internal volume of the high-pressure gas chamber and to smoothly slide the guide 37 with respect to the outer cylinder 12. Of liquid 38 is contained. The liquid 38 is hydraulic oil or the like, and by appropriately storing the liquid 38, the volume in the bellows outer chamber 13 is adjusted to a predetermined volume and the friction is reduced to reduce the friction of the bellows cylinder 14 and the guide 37. Make the operation smooth.

  Next, the operation of the gas spring 10 will be described.

  FIG. 4 shows a state where the overhead wire 50 is attached to the support column 52 via the gas spring 10. The support column 52 is a column fixed to the ground or the like. In the gas spring 10, the mounting tool 26 is connected to a mounting bracket 54 fixed to a support column 52 with a bolt or the like, and the mounting tool 28 is connected to an overhead wire 50 via an overhead wire joint 51. A support bar 56 is attached to the lower surface of the gas spring 10. The support bar 56 connects the fixing bracket 57 provided on the lower side of the outer cylinder 12 and the mounting bracket 58 fixed to the support column 52 to support the gas spring 10 from the lower side.

  When the gas spring 10 is fixed to the support column 52 and the overhead wire 50 is connected to the fixture 28, the rod 20 receives tension from the overhead wire 50. Then, the piston 18 moves to the left in FIG. 1 within the cylinder 16, compresses the cylinder chamber 34, and sends hydraulic oil to the bellows inner chamber 15 as indicated by the arrow in FIG. 2.

  FIG. 2 shows a state where the hydraulic oil flows from the cylinder chamber 34 into the bellows inner chamber 15. When the hydraulic oil flows into the bellows inner chamber 15, the peak portion of the bellows cylinder 14 is enlarged and the valley portion is reduced, that is, the volume of the gas chamber of the bellows outer chamber 13 is reduced. In FIG. 3, the deformation | transformation figure of the peak and valley of the bellows cylinder 14 calculated | required with the finite element method is shown. Thereby, the pressure in the bellows outer chamber 13 as a high pressure gas chamber rises, and the piston 18 is held at a position where the pressing force by the piston 18 and the inner pressure of the bellows outer chamber 13 are balanced.

  Accordingly, the overhead wire 50 shown in FIG. 4 is also affected by the internal pressure generated in the bellows outer chamber 13 in this state, that is, the tensile force equal to the pressing force received by the piston 18 from the hydraulic oil (in practice, the pressure in the low pressure gas chamber). .) Therefore, since the gas spring 10 can pull the overhead wire 50 with a predetermined force and the bellows cylinder 14 is provided outside the cylinder 16, the gas spring 10 can be configured substantially by the length of the cylinder 16. Can be set short.

  Next, the point which pulls the overhead wire 50 with a fixed tensile force regardless of temperature change using the gas spring 10 will be described.

The gas enclosed in the bellows outer chamber 13 is {(P × V) / T} = constant (a), where P is the pressure, V is the volume, and T is the temperature.
There is a relationship.

  From the above equation (a), the pressure P or the volume V changes with the change of the temperature T. Therefore, the movement amount of the rod 20 obtained from the volume change of the bellows outer chamber 13 due to the temperature change and the extension / contraction amount of the overhead wire due to the temperature change. Is set to be the same, the tension of the overhead wire can be made constant regardless of the temperature change.

  The condition for keeping the tension constant regardless of the temperature change is that the volume V of the gas sealed in the bellows outer chamber 13 is as follows.

V = A × L × α × T (b)
Here, A: the difference between the cross-sectional area of the rod 20 and the cross-sectional area of the piston 18, L: the length of the overhead wire, α: the linear expansion coefficient of the overhead wire, T: absolute temperature, and the expansion of the liquid in the liquid chamber In this case, the gas volume is V = {(A × L × α) − (Voil × β)} × T (c)
In the formula (c), Voil: volume of liquid, β: volume expansion coefficient of liquid. With the gas volume V thus obtained, the tension of the overhead wire 50 can be kept constant regardless of the temperature change.

  In this way, the amount of change due to the temperature of the overall length of the overhead wire 50 is taken into account as the volume change of the gas sealed in the high-pressure gas chamber, that is, the bellows outer chamber 13 (the expansion and contraction of the hydraulic oil and the volume change in the low-pressure gas chamber are also considered By setting the volume of the bellows outer chamber 13, the gas filling amount, etc. so that the volume of the gas accurately changes by that amount even if the length of the overhead wire 50 changes, the gas spring 10 Can always apply a constant tension to the overhead wire 50.

  In addition, the bellows cylinder 14 generates stress in peaks and valleys due to expansion and contraction. The number of repetitions of stress and expansion / contraction is determined by an endurance test. The generated stress is determined by the bellows shape and the number of bellows peaks. Therefore, the required number of bellows peaks is determined from the number of times of use.

  In contrast to the above embodiment, the fixture 26 of the outer cylinder 12 may be connected to a tension line (for example, the overhead wire 50), and the fixture 28 of the rod 20 may be fixed to the support column 52 side.

  As a comparative example, a rough calculation example calculated by omitting the oil amount is shown below.

  Overhead wire tension: about 35000 N (3500 kgf), overhead wire length: 800 m, center temperature: 15 ° C., temperature change width plus / minus: 30 ° C., overhead wire temperature elongation coefficient: 0.0000142 / ° C., rod diameter: 50 mm, piston diameter: 75 mm, Bellows effective diameter: 74.5mm, bellows permissible displacement for 10,000 times: 2.53mm / mountain, bellows minimum pitch: 2.45mm / mountain, bellows end length: 4.5mm .

  The gas volume (15 ° C.) for which the tension is constant can be obtained as about V = 8000 cubic cm from the equation (c). In this case, the bellows length is about 1800 mm. The cylinder stroke with respect to the temperature change is plus or minus 340.8 mm, and in the conventional example, the length of the gas spring is about 2500 mm as the sum of the bellows length and the cylinder stroke.

  On the other hand, in the above example, if the change in volume associated with the maximum piston stroke is set to the outer diameter and inner diameter of the bellows that can be within the allowable stress of the bellows by the cylinder length, the total length of the gas spring is approximately the cylinder stroke. Although the outer length corresponding to 682 mm can be suppressed and the outer diameter becomes larger, the length of the gas spring can be greatly shortened.

  Next, another example of the gas spring 10 is shown in FIG.

  In the gas spring 10, the cross-sectional shape of the bellows cylinder 14 is sharply bent at the outer peripheral end and the inner peripheral end as shown in the figure, and the abdomen is formed in a so-called wave shape. The bellows cylinder 14 is made of, for example, metal. When the bellows cylinder 14 is configured in this manner, the mounting length of each fold forming the valley can be shortened, more valleys can be formed, and the volume change amount of the bellows cylinder 14 Can be made larger than the entire length of the bellows cylinder 14, and the gas spring 10 having a wide operating range can be further downsized. The bellows cylinder 14 can also be applied to a gas spring that makes the tension of the overhead wire 50 constant.

  Furthermore, a bottom plate is attached to one end of the cylinder 16 in the axial direction, the cylinder 16 has a bottomed cylindrical shape, and a rod 20, hydraulic oil, a seal housing 27, and the like are assembled to the cylinder 16 to constitute a cylinder subassembly. Then, the bellows cylinder 14 may be fixed inside the outer cylinder 12 by attaching the axial end of the bellows cylinder 14, and the cylinder sub-assembly may be incorporated in the outer cylinder 12.

Sectional drawing which shows one Embodiment of the gas spring concerning this invention. The fragmentary sectional view which shows the gas spring of FIG. The figure which shows the deformation | transformation state of a bellows. The figure which shows the attachment state of a gas spring. The fragmentary sectional view which shows the other example of a gas spring.

Explanation of symbols

10 ... Gas spring 12 ... Outer cylinder 13 ... Bellows outer chamber (high pressure gas chamber)
14 ... Bellows cylinder 15 ... Bellows inner chamber (oil chamber)
16 ... Cylinder 18 ... Piston 20 ... Rod 34 ... Cylinder chamber (oil chamber)

Claims (6)

A piston,
A cylinder having the piston slidable therein;
An outer cylinder provided substantially coaxially with the cylinder on the outer periphery of the cylinder;
Between the outer cylinder and the cylinder, a metal bellows provided substantially coaxially with the cylinder,
A cylinder bottom plate that attaches the cylinder and hermetically closes and fixes the bellows and one axial end of the outer cylinder; and
A rod side plate that is attached to the cylinder and that airtightly closes and fixes the other end in the axial direction of the bellows and the outer cylinder and that is fixed and fixed to the piston, and a rod side plate that is slidably penetrated. With
One of a bellows inner chamber defined by the inside of the bellows and the outside of the cylinder, or a bellows outer chamber defined by the outside of the bellows and the inside of the outer cylinder, the cylinder, the piston, and the rod side plate The cylinder chamber partitioned by the cylinder chamber, one of the bellows inner chamber communicated with the cylinder chamber, or one of the bellows outer chamber, and the cylinder chamber as an oil chamber filled with hydraulic oil,
Furthermore, the other of the bellows inner chamber or the bellows outer chamber not connected to the cylinder chamber is configured as a high-pressure gas chamber in which a gas having a predetermined pressure is sealed.   The gas spring according to claim 1, wherein the bellows is incorporated between the cylinder and the outer cylinder in a state where the bellows is compressed in the axial direction in advance.   3. The gas spring according to claim 1, wherein the bellows has an end on the inner diameter side and an end on the outer diameter side sharply bent, and the abdomen is formed in a wave-like unevenness. .   The gas spring according to any one of claims 1 to 3, wherein a predetermined amount of liquid is stored in the high-pressure gas chamber.   The piston chamber defined by the cylinder, the piston, and the cylinder side plate is a low pressure gas chamber set to an internal pressure lower than the internal pressure of the high pressure gas chamber, and the dried inert gas is sealed in the low pressure gas chamber. The gas spring according to any one of claims 1 to 4, wherein:   One of the outer cylinder and the rod is connected to a tension line such as a train line or a power transmission line, the other of the outer cylinder and the rod is connected to a tension line support member, and the rod is moved by the pressure of the high-pressure gas chamber. The high-pressure gas chamber is set to a predetermined volume so as to be drawn into a cylinder and apply a predetermined tensile force to the tension line, and to keep the tensile force constant regardless of temperature fluctuations. The gas spring according to any one of 1 to 5.

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