JP2021116892A - Accumulator and its gas leakage detection method - Google Patents

Abstract

To provide an accumulator which can further effectively absorb the pulsation of a liquid pressure circuit.SOLUTION: An accumulator 1 comprises an accumulator main body 2 and a decompression part 3. The accumulator main body 2 has a main body part 4 partitioned into a liquid pressure chamber 6 and atmospheric pressure chamber 7, and the decompression part 3 is connected to the liquid chamber 6 side of the main body part 3, and has an inner chamber 13, an outer chamber 14 and a slide part 15. The inner chamber 13 is arranged so as to be communicative with the liquid pressure chamber, the outer chamber 14 is arranged so as to be communicative with a liquid pressure circuit which is connected with the accumulator 1, and the slide part 15 is partitioned into the inner chamber 13 and the outer chamber 14. An inner chamber bottom part 16 constituting a bottom of the inner chamber 13, and an outer chamber bottom part 17 constituting a bottom of the outer chamber 14 are arranged, and a relationship of S1>S2 (here, S1: an area of the inner chamber bottom part, and S2 is an area of the outer chamber bottom part) is satisfied.SELECTED DRAWING: Figure 1

Description

The present invention relates to an accumulator and a method for detecting a gas leak thereof.

Conventionally, there is an accumulator. The main body of the accumulator is divided into a hydraulic chamber and an atmospheric pressure chamber, and there are a bladder type accumulator in which these two chambers are partitioned by a bladder and a piston type accumulator in which these two chambers are partitioned by a piston (for example, Patent Document). See 1 or 2). Such an accumulator is connected to a circuit (hereinafter referred to as a hydraulic circuit, etc.) filled with a hydraulic fluid represented by a hydraulic circuit (hydraulic circuit, etc.), and is connected to a pressure accumulator and pressure holding / impact of the hydraulic circuit, etc. It is used for buffering and pulsation absorption.

Special Table 2019-521294 International release 2017/141719

In recent years, hydraulic circuits and the like corresponding to high-pressure hydraulic pressure (hydraulic, etc.) of 45 MPa or more, particularly 80 MPa or more, have come out. Therefore, there is a demand for an accumulator that supports such a high-pressure hydraulic circuit. The conventional accumulator follows the change in the hydraulic pressure in the hydraulic chamber, which changes according to the change in the hydraulic pressure of the hydraulic circuit, etc., and the pressure chamber contracts and expands, so that the hydraulic chamber and the hydraulic pressure The hydraulic fluid is supplied and discharged to and from the circuit, etc., and the above-mentioned functions are realized.

On the other hand, it is known that the polytropic index, which is an index of compression / expansion of a gas, increases with the pressure of the gas, and the higher the pressure, the larger the value. That is, the gas has a property that the higher the pressure, the smaller the amount of change in volume with respect to the amount of change in pressure.

On the other hand, the pressure in the atmospheric pressure chamber cannot be freely set, but is determined according to the hydraulic pressure in the hydraulic chamber. In a conventional accumulator, a hydraulic circuit or the like and a hydraulic chamber are communicated with each other, so that the hydraulic pressure in the hydraulic chamber is substantially the same as the hydraulic pressure in the hydraulic circuit or the like. The higher the hydraulic pressure in the pressure chamber, the higher the pressure in the pressure chamber.

Therefore, in the conventional accumulator, as the hydraulic pressure of the connected hydraulic circuit or the like becomes higher, it becomes difficult to contract / expand the atmospheric pressure chamber by following the change of the hydraulic pressure of the hydraulic pressure circuit or the like. Along with this, the amount of hydraulic fluid supplied and discharged between the hydraulic chamber and the hydraulic pressure circuit or the like decreases, so the higher the hydraulic pressure of the connected hydraulic pressure circuit or the like, the lower the efficiency. There was a problem.

Therefore, an object of the present invention is to provide an accumulator that operates more efficiently.

The present invention is an accumulator, comprising an accumulator main body and a decompression unit. The accumulator main body has a main body portion divided into a hydraulic pressure chamber and a pressure chamber, and the decompression portion is the main body portion. It is connected to the hydraulic chamber side, has an inner chamber, an outer chamber, and a sliding portion, and the inner chamber is provided so as to be communicative with the hydraulic chamber, and the outer chamber is provided. Is provided so as to be communicable with the hydraulic circuit to which the accumulator is connected, and the sliding portion divides the inner chamber and the outer chamber, and constitutes the bottom of the inner chamber, and the inner chamber bottom portion thereof. It has an outer chamber bottom that constitutes the bottom of the outer chamber, _{and satisfies S 1} > S ₂ (provided that S ₁ : the area of the inner chamber bottom and S ₂ : the area of the outer chamber bottom). It is an accumulator characterized by being provided.

Further, the present invention is a method for detecting gas leakage of the accumulator, which includes a step of measuring the pressure in the pressure chamber, a step of measuring the working hydraulic pressure of the hydraulic circuit to which the accumulator is connected, and the pressure. It has a step of comparing the pressure in the room with the working hydraulic pressure of the hydraulic circuit, and has S ₁ P ₃ <S ₂ P ₄ (however, P ₃ : the pressure in the atmospheric pressure chamber, P ₄ : the hydraulic pressure. This is a gas leak detection method characterized in that it is determined to be a gas leak when the hydraulic pressure of the circuit is detected.

In the present invention, the accumulator main body is connected to P ₁ <P ₂ (however, P ₁ : maximum working pressure of the accumulator main body, P ₂ : maximum pressure of the hydraulic circuit when the accumulator is not connected). It is possible to provide the decompression unit so as to satisfy S ₁ P ₁ ≧ S ₂ P _2. Further, the present invention can further include a pressure gauge provided so as to be able to measure the pressure in the atmospheric pressure chamber. Further, in the present invention, P ₂ ≧ 45 MPa can be set.

The present invention provides a depressurizing portion having an inner chamber, an outer chamber, and a sliding portion for partitioning the inner chamber and the outer chamber, and the area of the bottom of the inner chamber is calculated from the area of the bottom of the outer chamber. Since it is provided so as to be large, the hydraulic pressure in the hydraulic chamber can be reduced with respect to the hydraulic pressure in the hydraulic circuit or the like to which the accumulator is attached, thereby reducing the pressure in the atmospheric pressure chamber to a lower pressure. It is possible to operate the accumulator more effectively.

It is a vertical partial sectional view of the 1st Embodiment of this invention, and is the figure which shows the state before operating the hydraulic pressure circuit. It is a vertical partial cross-sectional view of the 1st Embodiment of this invention, and is the figure which shows the state at the time of operation of a hydraulic circuit. It is a vertical partial sectional view of the 2nd Embodiment of this invention, and is the figure which shows the state at the time of operation of a hydraulic circuit. It is a vertical partial sectional view of the 2nd Embodiment of this invention, and is the figure which shows the state of a gas leak. It is a schematic diagram of the pressure change in the atmospheric pressure chamber.

The first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The accumulator 1 is provided so as to be connectable to, for example, a hydraulic circuit (hydraulic circuit or the like), and includes an accumulator main body 2 and a decompression unit 3.

The accumulator main body 2 has a main body portion 4 and a hydraulic pressure side connecting portion 5 (hereinafter, also referred to as a connecting portion 5). The main body 4 is divided into a hydraulic chamber 6 and an atmospheric pressure chamber 7, and the atmospheric pressure chamber 7 is provided so as to be able to contract and expand.

In the present embodiment, the main body 4 has a substantially capsule shape with both ends open, the end on the pressure chamber 7 side is closed by the lid 8, and is connected to the end on the hydraulic chamber 6 side. It is combined with part 5. Further, the hydraulic chamber 6 and the atmospheric pressure chamber 7 are partitioned by a bladder 9 formed so as to be expandable, and the inside of the bladder 9 is the atmospheric pressure chamber 7. The means for partitioning the hydraulic chamber 6 and the atmospheric pressure chamber 7 can be appropriately selected, and may be partitioned by, for example, a piston (not shown). Further, the shape of the main body 4 and the like can be appropriately selected.

The connection portion 5 is provided on the hydraulic chamber 6 side of the main body portion 4, and has a poppet 11 provided so as to open and close the liquid supply / drainage hole portion 10 (hereinafter, also referred to as the hole portion 10) and the hole portion 10. Have. Further, the connecting portion 5 is connected to the decompression unit 3 and is provided so as to communicate with the hydraulic chamber 6 and the inner chamber 13 of the decompression unit 3, which will be described later, via the hole portion 10. In the present embodiment, the connection portion 5 is provided with a supply port 12 for supplying the hydraulic fluid to the hydraulic pressure chamber 6 and the inner chamber 13.

The decompression unit 3 has an inner chamber 13, an outer chamber 14, and a sliding portion 15 that separates the inner chamber 13 and the outer chamber 14. The inner chamber 13 is provided so as to communicate with the hydraulic chamber 6 via the hole 10, and the outer chamber 14 is provided so as to communicate with the hydraulic circuit.

The sliding portion 15 has an inner chamber bottom portion 16 forming the bottom of the inner chamber 13 and an outer chamber bottom portion 17 forming the bottom of the outer chamber 14, and is provided so as to be slidable in the decompression portion 3. .. Further, the sliding portion 15 is provided so that at least the area S _{1 of the inner chamber bottom portion 16 is larger than the area S 2} of the outer chamber bottom portion 17, that is, S ₁ > S ₂ .

In the present embodiment, the inner chamber bottom 16 and the outer chamber bottom 17 are R ₁ ≈ 2.2 _{R 2} (where R ₁ : the diameter of the inner chamber bottom 16 and R ₂ : the diameter of the outer chamber bottom 17), that is, It _{is formed in a substantially circular shape so that S 1} ≈ 5 S ₂ and they are arranged on substantially concentric circles in a plan view. The ratio of S ₁ and S ₂ may be appropriately selected within the range of _{S 1} > S _{2 as} long as the hydraulic pressure of the internal hydraulic fluid described later can be reduced as much as necessary.

Regarding the shape of the sliding portion 15 including the inner chamber bottom 16 and the outer chamber bottom 17 and the area ratio of the inner chamber bottom 16 and the outer chamber bottom 17, the hydraulic pressure of the hydraulic chamber 6 is only required. It suffices if it can be reduced, and it can be appropriately selected. Further, the sizes of the inner chamber 13, the outer chamber 14, and the sliding portion 15 can be appropriately selected according to the range of the working pressure of the accumulator 1.

In the accumulator 1, the hydraulic chamber 6, the hole 10 and the inner chamber 13 are in a state of communicating with each other at all times, and are filled with a hydraulic fluid (hydraulic oil or the like, hereinafter also referred to as an internal hydraulic fluid). Further, the atmospheric pressure chamber 7 is filled with an inert gas such as nitrogen so as to have a specified volume, and the pressure in the atmospheric pressure chamber 7 is determined according to the hydraulic fluid pressure of the internal hydraulic fluid. There is.

To fill the internal hydraulic fluid, after connecting the accumulator 1 to the hydraulic circuit, the inert gas is supplied to the atmospheric pressure chamber 7 until the pressure reaches a specified pressure to expand the accumulator 1, and the hole 10 is filled with the poppet 10. Block. After that, the internal hydraulic fluid is press-fitted from the supply port 11 until the specified pressure of the internal hydraulic fluid is reached, and the inner chamber 13 and the hydraulic fluid chamber 6 are filled with the internal hydraulic fluid.

When the hydraulic circuit is activated, the hydraulic fluid of the hydraulic circuit (hydraulic oil, etc., hereinafter also referred to as an external hydraulic fluid) flows into the outer chamber 14, and the external hydraulic fluid causes the hydraulic fluid to reach the bottom 17 of the outer chamber. The sliding portion 15 slides in the decompression portion 3 until the pressure is transmitted and the force applied to the outer chamber bottom 17 and the force applied to the inner chamber bottom 16 are balanced, whereby the pressure chamber is passed through the internal hydraulic fluid. 7 contracts, and the accumulator 1 is accumulating pressure.

At this time, since the area S ₁ of the inner chamber bottom 16 is larger than the area S ₂ of the outer chamber bottom 17, the hydraulic fluid pressure of the internal working fluid may, depending on their ratio, the external hydraulic fluid It will be reduced compared to the hydraulic fluid pressure. For example, in the present embodiment, since S ₁ ≈ 5S ₂ , the hydraulic fluid pressure of the internal hydraulic fluid is reduced to about 1/5 as compared with the hydraulic fluid pressure of the external hydraulic fluid. It becomes. That is, the pressure in the pressure chamber 7 is determined based on the reduced hydraulic fluid pressure of the internal hydraulic fluid.

In the accumulator 1, fluctuations in the hydraulic fluid pressure of the external hydraulic fluid are transmitted to the internal hydraulic fluid via the sliding portion 15 of the decompression unit 3, and the hydraulic fluid pressure in the hydraulic pressure chamber 6 fluctuates. As the pressure chamber 7 contracts and expands in accordance with the fluctuation of the hydraulic pressure in the hydraulic chamber 6, the sliding portion 15 slides, and the external chamber 14 and the hydraulic circuit are separated from each other. The hydraulic fluid is supplied and discharged. As a result, the accumulator 1 fulfills functions such as pressure accumulation, pressure holding, shock buffering, and pulsation absorption of the hydraulic circuit.

On the other hand, it is known that the higher the pressure of a gas, the higher the polytropic index, which is an index of compression / expansion of the gas, and the smaller the fluctuation of the volume due to the pressure fluctuation. Therefore, as the pressure in the pressure chamber 7 is lower, the accumulator 1 follows the fluctuation of the hydraulic pressure in the hydraulic chamber 6 and, by extension, the fluctuation of the hydraulic pressure of the external working liquid, and the atmospheric pressure. The chamber 7 contracts and expands more sensitively, and operates efficiently.

In the accumulator 1 of the present embodiment, it is possible to reduce the hydraulic pressure of the hydraulic chamber 6 with respect to the hydraulic pressure of the external medium. Therefore, the pressure in the pressure chamber 7, which is determined according to the hydraulic pressure of the hydraulic chamber 6, can be reduced as compared with the conventional accumulator, and can be operated more efficiently. Therefore, in the accumulator 1, even if the hydraulic pressure of the external medium, that is, the hydraulic pressure of the hydraulic circuit is 45 MPa or more, particularly 80 MPa or more, the accumulator or the hydraulic pressure is efficiently accumulated. It is possible to perform functions such as pressure holding, shock buffering, and pulsation absorption of the circuit.

Table 1 shows the pressure in the gas chamber 7 by operating the accumulator so as to repeat the accumulation of pressure due to the inflow of the hydraulic fluid from the hydraulic pressure circuit to the accumulator and the discharge of the hydraulic hydraulic pressure from the accumulator to the hydraulic pressure circuit at 1-second intervals. Is changed between the minimum operating pressure and the maximum operating pressure as shown in FIG. 5, and shows the effect of the presence or absence of the pressure reducing unit 3 on the supply and discharge of the hydraulic fluid between the accumulator and the hydraulic pressure circuit. be. The volume of the accumulator body of each accumulator is 1 L for comparison.

A is a case where the decompression unit 3 is not provided, and B is a case where the decompression unit 3 is provided. That is, the minimum operating pressure and the maximum operating pressure of B are reduced to about 1/5 by the decompression unit 3. In the table, the gas filling pressure is the initial pressure in the pressure chamber 7.

Comparing A and B in Table 1, B has a smaller polytropic index than A because the pressure in the pressure chamber 7 is reduced by the decompression part, and the hydraulic pressure circuit from the accumulator. The amount of hydraulic fluid pressure discharged to (the amount of discharge) is about 2.6 times. That is, Table 1 also shows that B provided with the decompression unit 3 operates more efficiently than A without the decompression unit 3. Conversely, in this case, when it is necessary to secure a discharge amount of 0.040 L, it is sufficient to set _{S 1} ≈ 5 S _{2 in the decompression unit 3.}

The following can be mentioned as secondary effects of this embodiment.
(A) The conventional accumulator needs to have a withstand voltage performance (maximum working pressure) equal to or higher than the maximum pressure of the connected hydraulic circuit. Therefore, it is necessary to increase the withstand voltage performance as the maximum pressure of the hydraulic circuit is higher. Therefore, the higher the maximum pressure of the hydraulic circuit, the more difficult it is to design the accumulator itself, and the thicker the wall thickness of the main body and its parts is, the heavier the weight becomes and the more difficult it is to handle. There was a problem.

On the other hand, since the accumulator 1 of the present embodiment can reduce the pressure in the internal medium and the pressure chamber 7 with respect to the hydraulic pressure of the external medium, the hydraulic pressure circuit connected to the accumulator main body 2 is connected. With respect to the maximum pressure, the withstand voltage performance of the conventional accumulator is not required. That is, the accumulator main body 2 may have P ₁ <P ₂ (however, P ₁ : the maximum working pressure of the accumulator main body 2 and P ₂ : the maximum pressure of the hydraulic circuit when the accumulator 1 is not connected). It is possible. Therefore, as compared with the conventional accumulator, the design can be facilitated and the weight can be reduced. It is also possible to divert the conventional accumulator for lower pressure to the accumulator for higher pressure. Naturally, it is possible to reduce costs.

In this case, pressure reducing unit 3 (sliding portion 15), the area S ₂ of the internal chamber bottom 16 of the area S ₁ and the outer chamber bottom 17 is at least the maximum operating pressure P ₁ and the accumulator 1 of the accumulator body 2 is connected _{In relation to the maximum pressure P 2} of the hydraulic circuit when the pressure is not provided, it is sufficient if the hydraulic pressure circuit is provided so as to satisfy at least S ₁ P ₁ ≥ S ₂ P ₂ (however, S ₁ > S _2). Become. In the present invention, the maximum pressure and the maximum working pressure are synonymous with the definitions of Japanese Industrial Standards JISB0142: 2011.

(B) In the conventional accumulator, the hydraulic fluid to which the accumulator is connected and the hydraulic chamber are communicated with each other, so that the hydraulic fluid can be changed between the hydraulic circuit side and the accumulator side. However, in the present embodiment, since the accumulator main body 2 side and the hydraulic circuit side are separated by the decompression unit 3, different types of hydraulic fluids are used for the internal medium and the external medium. This makes it possible to select a hydraulic fluid suitable for each of the accumulator 1 side and the hydraulic circuit side.

A second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The difference from the first embodiment is that the pressure gauge 18 is provided. The configuration shown by the same reference numerals as those of the same embodiment is the same as that of the same embodiment, and thus the description thereof will be omitted.

In the present embodiment, the lid portion 8 that closes the end of the main body portion 4 on the pressure chamber 7 side is provided with a pressure gauge 18, so that the pressure in the pressure chamber 7 can be constantly monitored. By doing so, in the present embodiment, the gas leak of the accumulator 1 can be detected by using the decompression unit 3.

More precisely, the pressure P ₃ in the pressure chamber 7, if the accumulator 1 if operating properly, equilibrium is to be established between the hydraulic fluid pressure of the internal working fluid. Therefore, S ₁ P ₃ ≈ S ₂ P ₄ is established between the pressure P ₃ and the hydraulic pressure P _{4 of the external hydraulic fluid.} This relationship is that if the accumulator 1 is operating normally, when the hydraulic pressure P ₄ rises, the bladder 9, that is, the pressure chamber 7, contracts, and P ₃ also rises. On the contrary, when the hydraulic fluid pressure P ₄ drops, the pressure chamber 7 expands and P ₃ also drops, so that the pressure chamber 7 is held (this also applies to the first embodiment). be).

On the other hand, the pressure P ₃ of the gas chamber 7 when gas leakage occurs is that drops to the accumulator 1. For this the change in the hydraulic fluid pressure inside the hydraulic fluid by the gas leakage does not, by the hydraulic fluid pressure, minute the pressure P ₃ drops, the gas chamber 7 becomes possible to shrink more than expected.

On the other hand, the sliding portion 15 of the pressure reducing portion 3 slides closer to the gas chamber 7 as the pressure chamber 7 contracts. When the pressure chamber 7 contracts more than expected, the sliding portion 15 collides with the end of the inner chamber 13, the connection portion 5 in the present embodiment, and slides further toward the pressure chamber 7. It becomes impossible to do so, and the hydraulic pressure of the internal hydraulic fluid does not rise any more.

Therefore, when a gas leak occurs in the accumulator 1, _{the pressure P 3} in the pressure chamber 7 does not rise and does not change _{even though the hydraulic pressure P 4 of the external hydraulic fluid rises, and S 1} P ₃ ≈ S ₂ P ₄ collapses, and S ₁ P ₃ <S ₂ P ₄ becomes.

Thus, (1) by the pressure gauge 18, the pressure _{P 3} is measured by a pressure gauge H1 attached to (2) hydraulic circuit H, to measure the hydraulic fluid pressure _{P 4,} (3) measured pressure P _{By comparing 3} with the hydraulic pressure P ₄ and confirming that (4) S ₁ P ₃ <S ₂ P ₄ , it becomes possible to detect a gas leak in the accumulator 1. _{The gas leak may be detected by calculating S 1} P ₃ and S ₂ P ₄ based on the value of the pressure gauge H1 and the value of the pressure gauge 18, and comparing them, but simply the pressure gauge. This may be performed with no change in the value of the pressure gauge 18 (pressure P ₃ ) regardless of the increase in the value of H1 (hydraulic pressure P _4). Moreover, these steps may be performed by human perception or may be performed mechanically.

Although the present invention has been described based on the above-described embodiment, the present invention is not limited to the above-described embodiment and can be appropriately modified as long as the gist of the invention is not changed.

1 accumulator 2 accumulator body 3 decompression part 4 body part 5 hydraulic pressure side connection part 6 hydraulic pressure chamber 7 atmospheric pressure chamber 8 lid 9 bladder 10 water supply / drainage hole 11 poppet 12 supply port 13 inner chamber 14 outer chamber 15 sliding part 16 Inner chamber bottom 17 Outer chamber bottom 18 Pressure gauge H Hydraulic circuit H1 Pressure gauge P Pressure R Diameter S Area

Claims (5)

It ’s an accumulator,
Equipped with an accumulator body and a decompression unit,
The accumulator main body has a main body portion divided into a hydraulic pressure chamber and an atmospheric pressure chamber.
The decompression portion is connected to the hydraulic chamber side of the main body portion, and has an inner chamber, an outer chamber, and a sliding portion.
The inner chamber is provided so as to communicate with the hydraulic chamber.
The outer chamber is provided so as to communicate with the hydraulic circuit to which the accumulator is connected.
The sliding portion has an inner chamber bottom that divides the inner chamber and the outer chamber and constitutes the bottom of the inner chamber, and an outer chamber bottom that constitutes the bottom of the outer chamber. An accumulator characterized in that it is provided so as to satisfy S ₁ > S ₂ (where S ₁ : the area of the inner chamber bottom and S _{2: the area of the outer chamber bottom).} The accumulator body is _{provided so as to satisfy P 1} <P ₂ (where P ₁ : maximum working pressure of the accumulator body, P ₂ : maximum pressure of the hydraulic circuit when the accumulator is not connected). ,
The accumulator according to claim 1, wherein the decompression unit is _{provided so as to satisfy S 1} P ₁ ≧ S ₂ P _2. The accumulator according to claim 1 or 2, further comprising a pressure gauge provided so as to be able to measure the pressure in the atmospheric pressure chamber. The accumulator according to claim 2 or claim 3, wherein P _{2 ≥ 45 MPa.} The method for detecting a gas leak in an accumulator according to claim 3 or claim 4, which cites claim 3.
The process of measuring the pressure in the atmospheric pressure chamber and
A step of measuring the hydraulic pressure of the hydraulic circuit to which the accumulator is connected, and
It has a step of comparing the pressure in the atmospheric pressure chamber with the hydraulic pressure of the hydraulic circuit.
A gas leak characterized in that it is determined as a gas leak when S ₁ P ₃ <S ₂ P ₄ (where P ₃ : pressure in the atmospheric pressure chamber, P _{4: hydraulic pressure of the hydraulic pressure circuit) is detected.} Detection method.

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