JP2009092143A - Accumulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an external gas type accumulator capable of reducing a pressure difference between the inside and the outside of a bellows so as to restrict the abnormal deformation of the bellows by comprising a structure for reducing a pressure difference generated when liquid sealed in a liquid chamber or sealed gas is expanded by heat when so-called zero-down is caused. <P>SOLUTION: This accumulator has a pressure difference adjusting mechanism 21 for reducing a pressure difference generated when liquid sealed in a liquid chamber 11 or sealed gas is expanded by heat when the so-called zero-down is caused. The adjusting mechanism 21 has a movable plate 22 supported by a second bellows 23 at the gas chamber 10 side of a bellows cap 8 and a communication path 24. In a normal operation, the cap 8 is moved together with the plate 22, and when the so-called zero-down is caused, the cap 8 is moved together with the plate 22 and brought in contact with a seal 13, and when liquid or sealed gas is expanded by the heat, the cap 8 is left to be brought in contact with the seal 13 and the plate 22 is moved to a position wherein liquid pressure and gas pressure are kept in balance with each other while extending the second bellows 23 to the position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an accumulator used as a pressure accumulator or a pulse pressure attenuator. The accumulator of the present invention is used, for example, for hydraulic piping in vehicles such as automobiles.

  Conventionally, a bellows is arranged inside an accumulator housing having an oil port connected to a pressure pipe so that the internal space of the housing is divided into a gas chamber for containing high-pressure gas and a liquid chamber communicating with a port hole. As shown in FIG. 4, the accumulator includes an end (floating end) 51 a having a bellows cap 52 attached to the other end (fixed end) 51 b of the upper portion of the housing 53. A type in which the inner peripheral side of the bellows 51 is a gas chamber 55 and the outer peripheral side is a liquid chamber 56 by being fixed to the end cover 54 (the gas chamber 55 is set on the inner peripheral side of the bellows 51, so “inner gas type” And a bellows 5 in which a bellows cap 52 is attached to one end (floating end) 51a as shown in FIG. The other end (fixed end) 51b of the bellows 51 is fixed to the oil port 57 below the housing 53, whereby the outer peripheral side of the bellows 51 is the gas chamber 55 and the inner peripheral side is the liquid chamber 56 (the gas chamber is on the outer peripheral side of the bellows 51). 55 is set, and is referred to as “external gas type” (see Patent Document 2 or 3).

  Here, in the accumulator connected to the pressure piping of the device, when the operation of the device is stopped, the liquid (oil) is gradually discharged from the port hole 58, and in the external gas type accumulator of FIG. The bellows 51 gradually contracts due to the gas pressure, and the seal 59 provided on the lower surface of the bellows cap 52 comes into contact with the mating member 60 and enters a so-called zero-down state. In this zero-down state, a part of the liquid is confined in the liquid chamber 56 (the space between the bellows 51 and the seal 59) by the seal 59, and the pressure of the confined liquid and the gas pressure in the gas chamber 55 are balanced. Therefore, it is set as the structure which suppresses that an excessive stress acts on the bellows 51 and an abnormal deformation | transformation generate | occur | produces.

  However, when the zero-down due to such operation stop is performed at a low temperature and the temperature rises in this state, the liquid and the sealed gas confined in the liquid chamber 56 are thermally expanded, and the pressure is increased. In this case, the degree of increase in the pressure of the liquid is larger than that of the sealed gas, but since the pressure receiving area in the bellows cap 52 is set smaller than that of the sealed gas, the bellows must be set so that the liquid pressure is not significantly larger than the gas pressure. The cap 52 does not move. Therefore, a large pressure difference of several MPa may occur between the liquid pressure inside and outside the bellows 51 and the gas pressure. If such a large pressure difference occurs, the bellows 51 is abnormally deformed or the seal 59 is damaged. There is a risk that.

JP 2005-315429 A JP 2001-336502 A JP 2007-187229 A

The accumulator shown in FIG. 6 is an external gas type accumulator similar to the accumulator shown in FIG. 5, and an auxiliary liquid chamber 71 is provided on the inner peripheral side of the bellows 51, and a piston seal 73 is attached to the auxiliary liquid chamber 71. The following inconvenience is pointed out because it has a unique configuration in which the piston 72 is inserted in such a manner that the piston 72 can be stroked (see Patent Document 4).
(A) The bellows 51 can be extended only by the volume of the auxiliary liquid chamber 71 (the expansion of the bellows 51 is limited when the volume of the auxiliary liquid chamber 71 is increased, and the bellows 51 is extended when the volume of the auxiliary liquid chamber 71 is reduced). The amount of liquid decreases and the amount of extension cannot be increased).
(B) Since the stroke is performed with the piston 72 sealed by the piston seal 73, the slip resistance due to the seal surface pressure is large, and the movement of the bellows 51 is slowed by the loss (the function as an accumulator is reduced).
JP 2003-278702 A

Furthermore, Patent Document 5 below discloses an accumulator having a structure in which a secondary piston is connected to a bellows cap via a secondary bellows. However, this conventional technique has the following disadvantages.
(C) Since the bellows contracts when the secondary bellows is extended during zero down, and the bellows contraction stops when the secondary piston reaches the lowermost surface, a sufficient bellows expansion / contraction stroke cannot be secured.
Japanese translation of PCT publication No. 2005-500487

  In view of the above, the present invention provides an external gas type accumulator having a mechanism for reducing the pressure difference generated when the liquid confined in the liquid chamber and the sealed gas are thermally expanded at the time of zero-down. An object of the present invention is to provide an accumulator capable of reducing the pressure difference and suppressing the bellows from being deformed abnormally.

  In order to achieve the above object, an accumulator of the present invention includes an accumulator housing having an oil port connected to a pressure pipe, a gas chamber disposed inside the housing and enclosing a high-pressure gas in the internal space of the housing, and A bellows for partitioning into a liquid chamber communicating with the port hole, the bellows having a fixed end fixed to the oil port and a bellows cap at the floating end, the outer periphery of the bellows being a gas chamber, an inner periphery In the accumulator in which the side is a liquid chamber, and the inner surface of the oil port is provided with a seal that closes the liquid chamber at the time of zero down and traps a part of the liquid in the liquid chamber, the accumulator is trapped in the liquid chamber at the time of zero down A pressure difference adjusting mechanism for reducing a pressure difference generated when the liquid and the sealed gas are thermally expanded; Has a movable plate supported by a second bellows on the gas chamber side of the bellows cap, and a communication passage that communicates the inner peripheral space of the bellows and the space between the bellows cap and the movable plate at the time of zero down, Comprises a through-hole provided in the bellows cap, and the bellows cap moves with the movable plate during steady operation, and at zero down, the bellows cap moves with the movable plate and contacts the seal, and the liquid and At the time of thermal expansion of the sealed gas, the bellows cap is in contact with the seal, and the movable plate moves while extending the second bellows to a position where the liquid pressure and the gas pressure are balanced.

  In the present invention having the above configuration, the fixed end of the bellows is fixed to the oil port, and the outer peripheral side of the bellows is a gas chamber and the inner peripheral side is a liquid chamber. Therefore, the accumulator of the present invention is an external gas type accumulator.

  The accumulator of the present invention operates as follows.

During steady operation ...
Since the bellows cap moves away from the seal by moving with the movable plate, the port hole and the liquid chamber (the space between the bellows and the seal) communicate with each other. Accordingly, since liquid having a pressure at that time is introduced from the port hole to the liquid chamber as needed, the bellows cap moves together with the movable plate so that the liquid pressure and the gas pressure are balanced.

Zero down ...
When the operation of the device is stopped, the liquid in the liquid chamber is gradually discharged from the port hole, and accordingly, the bellows contracts due to the enclosed gas pressure, and the bellows cap moves together with the movable plate in the bellows contracting direction to contact the seal. When the bellows cap comes into contact with the seal, the liquid chamber (the space between the bellows and the seal) is closed and a part of the liquid is confined in the liquid chamber, so that no further pressure drop occurs. Gas pressure will be balanced.

During thermal expansion in a zero-down state ...
If the liquid and the sealed gas that are confined in the liquid chamber due to an increase in ambient temperature or the like when the bellows cap is in contact with the seal in the zero down state are thermally expanded, the pressure of the liquid is greater than that of the gas. appear. Here, in the present invention, as described above, the movable plate is provided on the gas chamber side of the bellows cap via the second bellows, and further, the communication path for communicating the inner peripheral space of the bellows with the space between the bellows cap and the movable plate at the time of zero down Therefore, when a pressure difference occurs, the movable plate immediately moves while extending the second bellows to reduce the pressure difference. Accordingly, since a large pressure difference is suppressed from occurring inside and outside the bellows, it is possible to prevent the bellows from being deformed abnormally due to the pressure difference.

  During this thermal expansion operation, the bellows cap is restricted by the pressure receiving area by the seal, so it remains in contact with the seal and does not move (do not move). Therefore, only the movable plate moves while extending the second bellows. The movable plate does not come into contact with the seal, and therefore is not limited by the pressure receiving area by the seal, and therefore moves immediately when a pressure difference occurs.

  Therefore, according to the accumulator of the present invention that operates as described above, in the external gas type accumulator, it is possible to reduce the pressure difference generated when the liquid confined in the liquid chamber and the filled gas are thermally expanded at the time of zero down. Therefore, the pressure difference between the inside and outside of the bellows can be reduced and the bellows can be prevented from being deformed abnormally. Accordingly, the durability of the accumulator can be improved by extending the bellows. In addition, since the auxiliary liquid chamber and the secondary bellows are not provided, the problems (a), (b), and (c) are eliminated.

The present invention includes the following embodiments.
(1) Enclose high-pressure gas outside the bellows and allow liquid to enter and exit the bellows through the port hole. A bellows (second bellows) is welded to the gas chamber side of the bellows cap, and the opposite end of the welded bellows is closed with a metal plate (movable plate), and the outer diameter is larger than the seal contact portion of the bellows cap. A liquid communication hole is provided on the side. When the bellows cap is zero-down, the bellows cap comes into contact with the seal provided in the oil port to prevent the liquid inside the bellows from flowing out. When the liquid inside the bellows thermally expands in the zero down state, the liquid moves through the communication hole of the bellows cap, and the metal plate moves up and down to prevent the pressure difference inside and outside the bellows from being generated.
(2) Since it is sealed by the bellows cap at the time of zero down, the pressure receiving area of the gas pressure in the metal plate and the liquid pressure inside the bellows becomes equal. The metal plate and the bellows cap are connected by a bellows, and the bellows cap has a communication hole. Therefore, even if the bellows cap is pressed onto the oil port, the metal plate can freely move up and down within a certain range. it can. When the liquid inside the bellows thermally expands, the metal plate can move to a position where the gas pressure and the liquid pressure are balanced while the bellows cap is pressed against the oil port, so there is no differential pressure inside and outside the bellows. The bellows is not deformed.

  Next, embodiments of the present invention will be described with reference to the drawings.

  1 to 3 show an entire cross section or a partial cross section of an accumulator 1 according to an embodiment of the present invention. FIG. 1 shows a state during thermal operation, FIG. 2 shows a state during thermal expansion, and FIG. 3 shows a state during thermal expansion in a zero down state.

  The accumulator 1 according to this embodiment is a metal bellows type accumulator using a metal bellows as the bellows 7 and is configured as follows.

  That is, first, an accumulator housing 2 having an oil port 4 connected to a pressure pipe (not shown) is provided, and a bellows 7 is disposed inside the housing 2 so that the internal space of the housing 2 encloses high-pressure gas. The chamber 10 is partitioned into a liquid chamber 11 communicating with the port hole 5 of the oil port 4. As the housing 2, a combination of a bottomed cylindrical shell 3 and an oil port 4 fixed to the opening of the shell 3 is depicted, but the component split structure of the housing 2 is particularly limited. For example, the bottom of the shell 3 may be an end cover separate from the shell, and in any case, gas is injected into the gas chamber 10 into the bottom of the shell 3 or a component corresponding thereto. Gas inlets (not shown) are provided.

  The bellows 7 has its fixed end 7a fixed to the inner surface of the flange portion of the oil port 4 which is the inner surface on the port side of the housing 2, and the disk-shaped bellows cap 8 is fixed to the floating end 7b. Is an external gas type accumulator in which a gas chamber 10 is arranged on the outer peripheral side of the bellows 7 and a liquid chamber 11 is arranged on the inner peripheral side of the bellows 7. Further, as shown in FIG. 2, a damping ring 9 is attached to the outer peripheral portion of the free end 7 b in order to prevent the bellows 7 and the bellows cap 8 from contacting the inner surface of the housing 2.

  On the inner side of the port hole 5, that is, on the inner surface (upper surface in the figure) of the oil port 4, annular first and second step portions 4b and 4c are sequentially arranged on the inner peripheral side of the annular stopper projection (sitting surface) 4a. The seal 13 is formed and fitted to the first step 4b, and is retained by the seal holder 14 fitted to the second step 4c. The seal 13 closes the liquid chamber 11 (the space between the bellows 7 and the seal 13) when the accumulator 1 is zero-down, and confines a part of the liquid in the liquid chamber 11, and sufficiently exhibits this function. It is formed by a rubber-like elastic packing having an outwardly facing seal lip. The seal 13 may be an O-ring or an X-ring as long as sufficient sealing performance can be obtained, and the present invention does not particularly limit the shape of the seal 13.

  Further, the accumulator 1 is provided with a pressure difference adjusting mechanism 21 that reduces a pressure difference generated when the liquid confined in the liquid chamber 11 and the sealed gas are thermally expanded at the time of zero down.

  The pressure difference adjusting mechanism 21 includes a movable plate 22 supported on the gas chamber 10 side of the bellows cap 8 by a second bellows 23, and a space surrounded by the bellows 7, the oil port 4 and the bellows cap 8 at the time of zero down (bellows inner circumference). Space) 11 a and a communication path 24 that communicates the bellows cap 8 and the space 11 b between the movable plate 22.

  The movable plate 22 is made of a disc made of a rigid material such as metal, and is disposed on the gas chamber 10 side of the bellows cap 8 so as to be movable relative to the bellows cap 8. The second bellows 23 is disposed between the bellows cap 8 and the movable plate 22, and one end (fixed end) is coupled to the bellows cap 8 and the other end (floating end) is coupled to the movable plate 22.

  The bellows cap 8 and the movable plate 22 move together without relative movement during steady operation. Further, the bellows cap 8 and the movable plate 22 move together in a state where they are in contact with each other without being relatively moved during a steady operation. Accordingly, the bellows cap 8 is provided with a convex portion 8a toward the movable plate 22 so as to secure a storage space for the second bellows 23 between the two bellows caps 8 in a state where the bellows cap 8 is in contact with the movable plate 22. The tip of the convex portion 8a is in contact with the movable plate 22. Further, since the bellows cap 8 and the movable plate 22 move together without moving relative to each other during the steady operation, the second bellows 23 does not expand and contract at this time, and only the bellows 7 expands and contracts. Therefore, even if it is the same bellows, the second bellows 23 is harder than the bellows 7 (large spring constant) and hardly stretches.

  The bellows cap 8 contacts and separates from the seal 13. The bellows cap 8 stops when it comes into contact with the stopper projection 4a. Since the lip end of the seal 13 protrudes slightly from the stopper projection 4a, the bellows cap 8 is already in contact with the seal 13 when the bellows cap 8 contacts the stopper projection 4a.

  The communication path 24 is formed by a through hole 8 b provided in the bellows cap 8, and a plurality of the through holes 8 b are provided side by side in the circumferential direction of the bellows cap 8 with a predetermined interval. As described above, the communication passage 24 or the through-hole 8b allows the bellows inner circumferential space 11a and the space 11b between the bellows cap 8 and the movable plate 22 to communicate with each other during zero down. At the same time, the stopper protrusion 4a, the seal 13, and the bellows cap 8 The space 11c (seal outer space) 11c and the space 11b between the bellows cap 8 and the movable plate 22 are formed to communicate with each other.

  The accumulator 1 having the above configuration belongs to the category of the external gas type because the fixed end 7a of the bellows 7 is fixed to the inner surface of the flange portion of the oil port 4 which is the port side inner surface of the housing 2. Operates as follows.

During steady operation ...
That is, FIG. 1 shows a state during steady operation of the accumulator 1. The oil port 4 is connected to a pressure pipe of a device (not shown). In this steady state, the bellows cap 8 moves away from the seal 13 by moving together with the second bellows 23 and the movable plate 22, so that the port hole 5 and the liquid chamber 11 (the space between the bellows 7 and the seal 13) communicate with each other. ing. Accordingly, since liquid having a pressure at that time is introduced from the port hole 5 to the liquid chamber 11, the bellows cap 8 moves together with the second bellows 23 and the movable plate 22 so that the liquid pressure and the gas pressure are balanced.

Zero down ...
When the operation of the apparatus is stopped from the state of FIG. 1, the liquid in the liquid chamber 11 is gradually discharged from the port hole 5, and the bellows 7 is gradually contracted by the enclosed gas pressure, and the bellows cap 8 is secondly moved. Together with the bellows 23 and the movable plate 22, it gradually moves in the bellows contraction direction and contacts the seal 13. As shown in FIG. 2, the bellows cap 8 stops when it comes into contact with the stopper projection 4a. When the bellows cap 8 comes into contact with the seal 13 and the stopper projection 4a in this way, the liquid chamber 11 (the space between the bellows 7 and the seal 13) is closed and a part of the liquid is confined in the liquid chamber. No further pressure drop occurs in the liquid chamber 11, so that the liquid pressure and the gas pressure are balanced inside and outside the bellows 7. Therefore, it is possible to suppress abnormal deformation of the bellows 7 due to zero down. At the time of this zero down, the bellows cap 8 comes into contact with the seal 13 and the movable plate 22 does not come in contact. Therefore, the pressure receiving area of the movable plate 22 is limited by the seal 13 as in the above-described conventional bellows cap. Absent. Therefore, the pressure receiving area of the movable plate 22 is set to be equal on the gas chamber 10 side on one side and the liquid chamber 11 side on the opposite side.

During thermal expansion in a zero-down state ...
If the liquid confined in the liquid chamber 11 and the enclosed gas are thermally expanded due to an increase in the ambient temperature in the zero down state of FIG. 2, that is, with the bellows cap 8 in contact with the seal 13 and the stopper protrusion 4 a, the liquid is more than the gas. Since the degree of increase in pressure is large, a pressure difference is generated. However, in the accumulator 1, since the pressure receiving area of the movable plate 22 is set equal on the gas chamber 10 side and the liquid chamber 11 side, the movable plate 22 is moved to the second bellows 23 as shown in FIG. The movement immediately starts in the direction away from the bellows cap 8 while extending and stops at a position where the liquid pressure and the gas pressure are balanced. Accordingly, since a large pressure difference is suppressed from occurring inside and outside the bellows 7, it is possible to prevent the bellows 7 from being deformed abnormally due to the pressure difference. At this time, the bellows cap 8 remains in contact with the seal 13 as illustrated due to the difference in pressure receiving area between the upper and lower surfaces, so that the zero-down state is not eliminated. The liquid in the bellows inner circumferential space 11a flows into the space 11b between the bellows cap 8 and the movable plate 22 via the communication path 24, that is, the through hole 8b.

  Therefore, according to the accumulator 1, in the external gas type accumulator, it is possible to reduce the pressure difference generated when the liquid confined in the liquid chamber 11 and the filled gas are thermally expanded at the time of zero down. For this reason, the pressure difference between the inside and outside of the bellows 7 can be reduced, and abnormal deformation of the bellows 7 can be prevented. Accordingly, the durability of the accumulator 1 can be improved by extending the bellows 7.

  Further, in the zero down state of FIG. 2, as described above, the seal outer peripheral space 11 c is connected to the space 11 b between the bellows cap 8 and the movable plate 22 in the communication path 24 formed of the through hole 8 b provided in the bellows cap 8. There exists a function which makes it communicate, and, thereby, the high pressure by the thermal expansion of the liquid in the former space 11c is suppressed. Therefore, it is possible to prevent the seal 13 from being damaged due to the high pressure of the space 11c. In order to obtain this effect, instead of the through hole 8b, a radially extending groove may be provided on the end surface (upper surface) of the stopper projection 4a or the lower surface of the bellows cap 8 opposed thereto.

1 is an overall cross-sectional view showing a state during steady operation of an accumulator according to an embodiment of the present invention. Partial sectional view showing the accumulator at zero down Partial sectional view showing the state of thermal expansion in the zero-down state of the accumulator Cross section of accumulator according to conventional example Sectional view of an accumulator according to another conventional example Sectional view of an accumulator according to another conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Accumulator 2 Housing 3 Shell 4 Oil port 4a Stopper protrusion 4b, 4c Step part 5 Port hole 7 Bellows 7a Fixed end 7b Free end 8 Bellows cap 8a Protruding part 8b Through hole 9 Damping ring 10 Gas chamber 11 Liquid chamber 11a, 11b 11c Space 13 Seal 14 Seal holder 21 Pressure difference adjusting mechanism 22 Movable plate 23 Second bellows 24 Communication path

Claims (1)

An accumulator housing having an oil port connected to the pressure pipe; and a bellows arranged inside the housing and dividing the internal space of the housing into a gas chamber for containing high-pressure gas and a liquid chamber communicating with the port hole. The bellows has a fixed end fixed to the oil port and has a bellows cap at the floating end, the bellows has an outer peripheral side as a gas chamber, an inner peripheral side as a liquid chamber, and an inner surface of the oil port. Is an accumulator provided with a seal that closes the liquid chamber at the time of zero down and traps a part of the liquid in the liquid chamber,
A pressure difference adjusting mechanism for reducing a pressure difference generated when the liquid and the sealed gas confined in the liquid chamber at the time of zero down thermally expand;
The adjustment mechanism has a movable plate supported by a second bellows on the gas chamber side of the bellows cap, and a communication path that communicates the inner peripheral space of the bellows and the space between the bellows cap and the movable plate at the time of zero down, The communication path comprises a through hole provided in the bellows cap,
At the time of steady operation, the bellows cap moves with the movable plate, and at the time of zero down, the bellows cap moves with the movable plate and contacts the seal, and at the time of thermal expansion of the liquid and sealed gas, the bellows cap An accumulator, wherein the movable plate moves while extending the second bellows to a position where the liquid pressure and the gas pressure are balanced while being in contact with the seal.

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