JPH06137301A - Accumulator - Google Patents

Abstract

PURPOSE:To reduce the inconvenience caused by a sealed gas being dissolved into the gas volume regulating solution as much as possible, and easily supply a gas volume regulating solution into a gas chamber. CONSTITUTION:A partitioning member 20 is housed in a pressure vessel 14. The partitioning member 20 has a metal diaphragm bellows 21 to partition the inner part of the pressure vessel 15 into a gas chamber 30 and an oil chamber 45. A gas volume regulating solution 35 and a regulating member 36 are housed in the metal bellows 21. The regulating member 36 has a vertical hole 40 extending through in the axial direction. The vertical hole 40 is used when the gas volume regulating solution 35 is injected into the gas chamber 30, and allowed to communicate with an injection hole 31 and the gas chamber 30. On the end part 41 on the injection hole 31 side of the regulating member 36, a horizontal hole 42 orthogonal to the vertical hole 40 is provided. The horizontal hole 42 is allowed to communicate with the injection hole 31 and the gas chamber 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator suitable for accumulating pressure and absorbing pulsation of hydraulic pressure in equipment using hydraulic pressure such as various hydraulic equipment.

[0002]

2. Description of the Related Art In a conventional hydraulic circuit, an accumulator 100 as shown in FIG. 5 may be used as a means for absorbing hydraulic pulsation generated by driving a hydraulic pump or the like. This accumulator 100 has an outer cylinder member 10
An oil chamber 103, an air chamber 104 in which compressed gas is enclosed, a partition member 105 for partitioning these chambers 103, 104, and the like are provided inside a pressure vessel 102 including one and the like. Partition member 105
Includes a bellows 106 and a bellows cap 107. The bellows 106 is a metallic molded bellows (hereinafter referred to as U-shaped bellows) having a fold wall 108 having a U-shaped cross section as shown in FIG.
It is called a character bellows). Also the accumulator
The gas volume adjusting liquid 110 is contained in the air chamber 104 for the purpose of preventing the bellows 106 from being crushed to the contact length or less when a high pressure is applied to 100. Accumulator 100
An example of the specifications of is as follows. A mineral oil type is usually used for the gas volume adjusting liquid. An example of an enclosed gas is nitrogen.

[0003]

[Table 1]

[0004]

As described above, in the accumulator using the metal bellows, when the gas of a predetermined pressure and the gas volume adjusting liquid of a predetermined amount are contained inside the air chamber, a part of the gas is discharged. Dissolving in the gas volume adjusting liquid causes the following problems.

The amount of gas dissolved in the gas volume adjusting liquid varies depending on the pressure, and the amount of dissolution can be expressed as a volume conversion with respect to the gas volume adjusting liquid. For example, for some oils, 7.6% of the volume of the oil at 20 ° C. is shown as the volume into which nitrogen gas dissolves. In this case, as shown in the specifications of the accumulator (Table 1), the amount of the gas volume adjusting liquid was 38.6 cm ^3. If so, 2.9 cm ³ Is the amount of nitrogen gas that dissolves.

Table 1 above shows the accumulator specifications in the steady state. In this case, apparently nitrogen gas existing as a gas is 10.4 cm ³ However, the actual volume of the gas volume adjusting liquid is 2.9 cm ³ The total amount of gas enclosed in the air chamber is 13.3 cm ^{3 because} the nitrogen gas in Is. Therefore, in this case, the pressure for filling the nitrogen gas is 0.5 kgf / cm ² Is not enough, 0.93kgf / cm ^{2 in} consideration of dissolved gas It is necessary to fill the gas with. The nitrogen gas sealed at this pressure dissolves in the gas volume adjusting liquid over time, and finally reaches 0.5 kgf / cm ²
It becomes steady at and there is no further pressure change. This is the meaning of "steady state".

The same phenomenon as described above occurs when the accumulator operates. That is, when the air chamber is further compressed by the pressure of the oil introduced into the oil chamber in the accumulator, if the action of the enclosed gas is thermodynamically adiabatic change, the amount of the enclosed gas dissolved in the gas volume adjusting liquid Can be considered to be substantially unchanged. However, in the case of a pressure change over a long time that is thermodynamically considered as an isothermal change, the amount of dissolved gas changes according to the pressure.

For example, in the accumulator shown in Table 1 above, 10.0 kgf / cm ² Consider the case where the pressure of is added. In this case, if the above pressure is suddenly applied due to adiabatic change, the amount of dissolved gas does not change, so the apparent volume of nitrogen gas existing as a gas is 2.54 cm ³ with the polytropic index being 1.4. Becomes However, if this pressure is maintained for a long time, the gas temperature that rises due to adiabatic change will decrease to the ambient temperature, and the gas dissolution in the gas volume adjusting liquid will proceed further, so that the apparent gas that exists as a gas The volume decreases.

In the above example, the steady state is 13.3 cm ³ Gas of 0.5kgf / cm ^{2 in the} air chamber The pressure was 10.0 kgf / cm ² If it rises to
The gas volume is 1.85 cm ³ after sufficient time has passed. Becomes On the other hand, 38.6 cm ³ The amount of nitrogen gas that can be dissolved in the gas volume adjusting liquid of 2.9 cm ^{3 as} described above. Is. Therefore, in this case, all of the nitrogen gas is dissolved in the gas volume adjusting liquid, and the nitrogen gas existing as a gas disappears. Therefore, the function as an accumulator is lost.

Further, the nitrogen dissolved in the gas volume adjusting liquid under a high pressure has a very slow rate of separating into bubbles from the gas volume adjusting liquid even if the pressure is lowered again. This is especially true when the gas filling pressure is low as in the accumulator (Table 1) described above. Therefore, in the case of an accumulator that is normally used at low pressure, but may be held at high pressure for a long time under certain conditions, when the gas returns from the high pressure to the low pressure, until the gas is separated from the gas volume adjusting liquid. Causes a problem that the accumulator cannot operate normally.

Therefore, an object of the present invention is to provide an accumulator capable of reducing the problems caused by the gas enclosed in the air chamber dissolving in the gas volume adjusting liquid as much as possible.

[0012]

DISCLOSURE OF THE INVENTION The present invention, which was developed to achieve the above object, includes a pressure vessel and a partition which is housed inside the pressure vessel and divides the internal space of the pressure vessel into an oil chamber and an air chamber. In the accumulator using a metal bellows having a member and capable of expanding and contracting in the axial direction of the pressure vessel in the partition member, inside the bellows, a gas volume adjusting liquid for preventing the bellows from being crushed to a contact length. A vertical hole penetrating in the axial direction of the member and communicating with the inlet provided in the pressure vessel and the air chamber, and the inlet of the adjusting member. The lateral end is provided with a lateral hole penetrating in the direction intersecting with the vertical hole and communicating with the inlet and the air chamber.

[0013]

In the accumulator of the present invention, when the gas volume adjusting liquid is supplied to the air chamber, the pressure vessel is held with the inlet facing upward, and the nozzle inserted into the inlet causes the vertical hole of the adjusting member to move. Inject the gas volume adjusting liquid. The gas volume adjusting liquid supplied into the air chamber through the vertical hole accumulates from the bottom of the partition member, and the air in the air chamber is discharged to the outside through the horizontal hole of the adjusting member as the liquid level rises. When the pressure vessel is held with the inlet facing upwards, the horizontal hole communicates with the vertical hole at the top of the adjustment member,
Even if the liquid level of the gas volume adjusting liquid rises to the upper limit of the air chamber, the air in the air chamber can be almost completely discharged. Therefore, the air in the air chamber is replaced with the gas volume adjusting liquid. In this way, after a predetermined amount of the gas volume adjusting liquid is supplied to the air chamber, the gas having a predetermined pressure is supplied to the air chamber.

The oil chamber is filled with hydraulic oil, and this oil chamber is connected to a hydraulic circuit. The hydraulic pressure generated in the hydraulic circuit by hydraulic equipment such as a pump acts on the oil chamber of the accumulator,
The air chamber is compressed according to the hydraulic pressure. The greater the oil pressure, the more the bellows is compressed, but since the gas volume adjusting liquid and the adjusting member are stored inside the air chamber, the gas in the air chamber reaches the maximum pressure before the bellows contracts to the allowable close contact length. It is possible to prevent the bellows from being crushed below the contact length.

Since the gas volume adjusting liquid is a liquid, a part of the gas dissolves according to the magnitude of the pressure, but the adjusting member is a solid so that the gas does not substantially dissolve. Therefore, in the accumulator of the present invention, the amount of the gas volume adjusting liquid can be reduced by the volume of the adjusting member, and the amount of the gas dissolved in the gas volume adjusting liquid can be reduced. For this reason, even if the high pressure is maintained for a long time, a part of the enclosed gas can remain in the air chamber as a gas, and the function as an accumulator can be exhibited.

When a metal bellows (diaphragm bellows) having a diaphragm-shaped pleated wall is adopted as the partition member, the contact length becomes extremely shorter than that of the U-shaped bellows, so that the amount of the gas volume adjusting liquid used is increased. Less than U-shaped bellows. Therefore, the accumulator using the diaphragm bellows can further reduce the amount of gas dissolved in the gas volume adjusting liquid.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, the accumulator 10 of the present embodiment shown in FIG. 1 operates in a state of being connected to the hydraulic circuit 11.
The accumulator 10 is used to absorb hydraulic pressure pulsation generated in the hydraulic circuit 11 and store pressure. The hydraulic circuit 11 is various equipment including hydraulic devices 12, 13 and a pipeline 14.

The pressure vessel 15 of the accumulator 10 has a cylindrical outer cylindrical member 16 made of metal, and a first metallic end member 17 welded to one end side (bottom side) of the outer cylindrical member 16.
And a second end member 18 made of metal and welded to the other end of the outer tubular member 16. Pressure vessel 15
Has a rigidity that can withstand the working pressure of the hydraulic circuit 11 acting on the accumulator 10.

A partition member 20 is provided inside the pressure vessel 15. The partition member 20 includes a metal bellows 21. The fixed-side end portion 22 of the bellows 21 is airtightly joined to the bellows fixing portion 23 of the first end member 17 by welding. A bellows cap 25 and a bellows guide 26 are provided on the other end side of the bellows 21. The bellows guide 26 is made of synthetic resin having a small friction coefficient. The outer peripheral portion of the bellows guide 26 is in sliding contact with the inner peripheral surface of the outer tubular member 16, and the bellows 21 extends in the axial direction of the outer tubular member 16.
Is designed to be able to expand and contract smoothly.

The space inside the partition member 20 is used as an air chamber 30. Helium gas or nitrogen gas, which is an example of an inert gas, is filled in the air chamber 30 at a pressure higher than atmospheric pressure. The filled gas is used for the first end member 17
It is supplied to the air chamber 30 through the inlet 31 provided in the. After the gas is supplied, the inlet 31 is hermetically closed by a plug 32 using a bolt or the like.

A gas volume adjusting liquid 35 and an adjusting member 36 are housed in the air chamber 30 for the purpose of preventing the bellows 21 from being crushed to an allowable contact length. An example of the gas volume adjusting liquid 35 is mineral oil. The adjusting member 36 in the illustrated example is a cylindrical metal integrally formed with the end member 17, but in some cases, a member made separately from the end member 17 is fixed to the end member 17 by an appropriate fixing means. May be.

A vertical hole 40 is provided in the central portion of the adjusting member 36. The vertical hole 40 penetrates in the axial direction of the adjusting member 36, one end side of the vertical hole 40 communicates with the inlet 31, and the other end side of the vertical hole 40 communicates with the air chamber 30. Further, a lateral hole 42 is formed in the end portion 41 of the adjusting member 36 on the injection port 31 side.
Is provided. A plurality of horizontal holes 42 are provided radially in the radial direction of the adjusting member 36, and each is orthogonal to the vertical hole 40. One end of each lateral hole 42 communicates with the inlet 31. The other end of each lateral hole 42 is the air chamber 3
It communicates with 0.

A space surrounded by the outer peripheral surface of the partition member 20, the inner peripheral surface of the outer tubular member 16 and the end member 18 is used as an oil chamber 45. This oil chamber 45 is communicated with the hydraulic circuit 11 (see FIG. 2) through an introduction port 46 provided in the end member 18, so that a part of the oil flowing through the hydraulic circuit 11 can be introduced into the oil chamber 45. Has become.

On the surface of the bellows cap 25 on the oil chamber 45 side, a seal member 5 made of a rubber-like elastic body such as an elastomer is formed.
0 is provided. The seal member 50 constitutes the self-sealing mechanism 51. When the gas is supplied to the air chamber 30, the partition member 20 is extended by the pressure of the gas and the seal member 50 strikes the end member 18. Thus, the seal member 50 closes the introduction port 46 in a liquid-tight manner. By doing so, backup oil that has been injected in advance is trapped between the outer peripheral surface of the bellows 21 and the inner peripheral surface of the outer tubular member 16, and the outer surface of the bellows 21 is supported by this backup oil. .

As shown in FIG. 4, the bellows 21 is
A large number of diaphragm-shaped pleated walls 55 each having a corrugated cross section in its circumferential direction are formed in the axial direction of the bellows 21, and each pleated wall 55 is mutually compressed when the bellows 21 is compressed to a close contact length. It is shaped so that it can overlap. The diaphragm bellows 21 is not manufactured by welding, but the pleated wall 55 is formed by hydraulic bulge molding or the like from a single metal element pipe (not shown).
Is molded.

The contact pitch of the diaphragm bellows 21 is extremely small, and the contact length is greatly shortened when the number of peaks is the same (the number of pleated walls is the same) as compared with the conventional U-shaped bellows 106 (see FIG. 6). For example, conventional U-shaped bellows
The contact pitch of 106 is 1.23 mm, while the contact pitch of diaphragm bellows 21 is 0.5 mm. The gas volume adjusting liquid 35 described above requires a larger amount of liquid as the contact length of the bellows becomes longer. Therefore, the diaphragm bellows 21 of this embodiment having an extremely short contact length is
It is extremely effective in reducing the amount of the gas volume adjusting liquid 35 used.

When injecting the gas volume adjusting liquid 35 into the air chamber 30, as shown in FIG. 3, the pressure vessel 15 is held with the inlet 31 facing upward. Then, the nozzle 60 is inserted into the injection port 31, and the gas volume adjusting liquid 35 is injected into the vertical hole 40 by the nozzle 60. The gas volume adjusting liquid 35 injected into the air chamber 30 accumulates from the bottom of the partition member 20 and the liquid level rises.
2 and the inlet 31 to be discharged to the outside.

When the pressure vessel 15 is held with the inlet 31 facing upward as described above, the lateral hole 42 communicates with the inlet 31 at the uppermost portion of the adjusting member 36, so that the gas volume is increased. Even if the liquid level of the adjustment liquid 35 rises to the upper limit of the air chamber 30, the air in the air chamber 30 can be completely discharged. Therefore, the replacement of the air and the gas volume adjusting liquid 35 in the air chamber 30 is surely performed.
When it is necessary to discharge all the gas volume adjusting liquid 35 in the air chamber 30 for some reason, the inlet 31
If the pressure vessel 15 is turned upside down so that the horizontal hole 42 faces downward, the horizontal hole 42 communicates with the lowest position of the air chamber 30.
2 and the gas inlet 31 through the gas volume adjusting liquid 3 in the air chamber 30
5 can be discharged completely.

When only the vertical holes 40 are provided, the air remaining between the outer peripheral surface of the adjusting member 36 and the inner surface of the bellows 21 can be expelled when the gas volume adjusting liquid 35 is injected. Therefore, it becomes difficult to replace the air with the gas volume adjusting liquid 35. On the other hand, when only the lateral holes 42 are provided, when the gas volume adjusting liquid 35 is injected at high speed by the nozzle 60, the gas volume adjusting liquid 35 ejected from the nozzle 60 hits the inner surface of the bellows 21 and bounces toward the nozzle 60 side. ,
Since it may leak from the inlet 31, it may cause variation in the injection amount. However, in the present embodiment, the above-mentioned problems can be avoided by combining the vertical hole 40 and the horizontal hole 42, and a predetermined amount of the gas volume adjusting liquid 35 can be quickly injected into the air chamber 30.

After a predetermined amount of the gas volume adjusting liquid 35 is stored in the air chamber 30 by the above process, a gas having a predetermined pressure is supplied to the air chamber 30 through the inlet 31. Air chamber 30
When the gas is supplied to the partition member 20, the partition member 20 extends due to the pressure of the gas until the seal member 50 abuts against the end member 18, so that the introduction port 46 is closed. As a result, the backup oil that has been injected in advance is enclosed between the outer peripheral surface of the bellows 21 and the inner peripheral surface of the outer tubular member 16, and the outer surface of the bellows 21 is supported, so that gas pressure is applied. The bellows 21 is prevented from being excessively deformed.

As shown in FIG. 2, the accumulator 10 having the above-described structure is provided with the hydraulic circuit 1 connected to the introduction port 46.
The working hydraulic pressure of 1 acts on the oil chamber 45. When the oil pressure becomes higher than the pressure of the air chamber 30, the bellows 21 bends toward the contracting side, the volume of the air chamber 30 decreases, and the gas pressure rises. Further, when the hydraulic pressure acting on the oil chamber 45 becomes lower than the gas pressure in the air chamber 30, the bellows 21 bends toward the extension side. This gas spring action stores pressure and smoothes the pulsating component of hydraulic pressure.

In the accumulator 10, the air chamber 3
Assuming that only the gas volume adjusting liquid 35 is accommodated inside 0 and the adjusting member 36 is not used, the volume of the gas enclosed in the air chamber 30 is 10.4 cm ³ as in the accumulator of Table 1 above.
Then, by using the diaphragm bellows 21 of this embodiment having a small contact length, the amount of the gas volume adjusting liquid 35 is 22.5 cm ^3. And is reduced to 58% compared to the accumulator in Table 1. Therefore, in this case, if the enclosed gas is nitrogen, the amount of gas dissolved in the gas volume adjusting liquid 35 is
1.71 cm ^{3 when} converted to volume Becomes

In the above embodiment, the metal adjusting member 36 into which the gas does not dissolve is housed in the air chamber 30, and the amount of the gas volume adjusting liquid 35 can be reduced accordingly. The amount of dissolved gas is small.
For example, the volume is 13.2 cm ^3. When the adjusting member 36 of No. ³ is used, the amount of the gas volume adjusting liquid 35 used is 9.3 cm ^3. Therefore, it is reduced to 24% of the accumulator shown in Table 1. In this case, if the enclosed gas is nitrogen, the amount of gas dissolved in the gas volume adjusting liquid 35 is 0.71 cm ^{3 when} converted into volume. Becomes

Further, by using helium instead of nitrogen as the enclosed gas, the amount of gas dissolved in the gas volume adjusting liquid 35 can be further reduced. When the Ostwald coefficient indicating the solubility of the gas is compared, at 0 ° C., the nitrogen gas is 0.069, while the helium gas is 0.
Since it is 012, the dissolved amount is about 17%. Therefore, when the amount of the gas volume adjusting liquid 35 is the same, the amount of dissolved gas is about 1 by using helium gas.
It becomes / 6, and it is possible to reduce the influence of the enclosed gas dissolving in the gas volume adjusting liquid 35. For example, 9.3 cm ³ The amount of helium gas dissolved in the gas volume adjusting liquid 35 is 0.12 cm ^{3 in} terms of volume. And 4% of the accumulator in Table 1
Therefore, the influence of the gas dissolution on the accumulator characteristics can be significantly reduced.

Similar to the accumulator in Table 1, the gas filling pressure is 0.5 kgf / cm ^2. , Gas filled volume is 10.4cm
³ 10kgf / cm ² in an accumulator filled with helium gas so that The change when the pressure is applied is as follows. In the case of helium gas, the polytropic index is 1.67, so 10 kgf / cm ² The volume when adiabatic change is 3.19 cm ³ when compressed with the pressure of
Becomes Since the dissolution of the helium gas in the gas volume adjusting liquid 35 progresses with the passage of time, finally 1.4
6 cm ³ Helium gas existing as a gas is 1.34 cm ³ , The dissolved amount is 0.12 cm ³ Becomes That is, 10.0 kgf / cm ² The helium gas will not be completely dissolved even when the pressure is applied, and the function as an accumulator can be maintained.

For the reasons described above, helium is suitable as the gas to be sealed in the air chamber 30, but nitrogen gas can be used by appropriately selecting the combination with the gas volume adjusting liquid 35. For example, when a water glycol-based hydraulic oil is used as the gas volume adjusting liquid 35, the dissolved amount of nitrogen gas is reduced to about 40% of the mineral oil. Therefore, even if nitrogen gas is used, problems due to gas dissolution are reduced. Is effective on.
Further, the adjusting member 36 is not limited to a metal, and in short, as long as it is a solid having physical properties that are not attacked by the gas volume adjusting liquid 35 and that gas does not substantially permeate, for example, a block of synthetic resin may be used. Or an elastomer may be adopted.

[0037]

According to the present invention, since the amount of gas dissolved in the gas volume adjusting liquid is small, it is possible to reduce the influence of the gas dissolution on the accumulator characteristics. Further, even when the high pressure gas is held for a long time, a part of the enclosed gas can exist as a gas, and therefore the function as the accumulator is not lost. Then, by utilizing the vertical holes and the horizontal holes provided in the adjusting member, the gas volume adjusting liquid can be easily and easily injected into the air chamber.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an accumulator showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a usage mode of the accumulator shown in FIG.

3 is a cross-sectional view showing a state in which a gas volume adjusting liquid is being injected into the accumulator shown in FIG.

FIG. 4 is a sectional view of a part of a bellows used in the accumulator shown in FIG.

FIG. 5 is a vertical sectional view showing a conventional accumulator.

6 is a cross-sectional view of a portion of a U-shaped bellows used in the accumulator shown in FIG.

[Explanation of symbols]

10 ... Accumulator, 15 ... Pressure vessel, 20 ... Partition member, 21 ... Metal bellows, 30 ... Air chamber, 31 ... Injection port,
35 ... Gas volume adjusting liquid, 36 ... Gas volume adjusting member, 40
... vertical hole, 42 ... horizontal hole, 45 ... oil chamber.

Claims (2)

[Claims] 1. A pressure vessel, and a partition member which is housed inside the pressure vessel and partitions the internal space of the pressure vessel into an oil chamber and an air chamber, and the partition member expands and contracts in the axial direction of the pressure vessel. In an accumulator using a flexible metal bellows, a gas volume adjusting liquid and an adjusting member for preventing the bellows from being crushed to a close contact length are housed inside the bellows, and the adjusting member includes A vertical hole penetrating in the axial direction and communicating with the inlet provided in the pressure vessel and the air chamber, and penetrating in the direction intersecting the vertical hole at the inlet end of the adjusting member. An accumulator provided with a lateral hole communicating with the inlet and the air chamber. 2. The bellows is a diaphragm bellows formed by integrally molding a plurality of diaphragm-shaped pleated walls having corrugated cross-sections so that they can overlap each other when compressed to a close contact state from a metal tube. Accumulator described.