JP2009092142A - 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 mechanism 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 1 or sealed gas is expanded by heat when so-called zero-down is caused. The adjusting mechanism 21 has a movable plate 22 supported by a packing 23 at the oil port 4 side of a bellows cap 8 and a communication path 24. In a normal operation, the plate 22 is moved with the cap 8 in a state of being supported by the packing 23, and when the so-called zero-down is caused, the plate 22 is moved together with the cap 8 and brought in contact with a seal 23, and when the liquid or the sealed gas is expanded by the heat, the plate 22 is left to be brought in contact with the seal 13 and the cap 8 is moved to a position wherein the liquid pressure and the gas pressure are kept in balance with each other while compressing the packing 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. 5, 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 pipe 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. 7 is an external gas type accumulator similar to the accumulator shown in FIG. 6, 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 according to claim 1 of the present invention includes an accumulator housing having an oil port connected to a pressure pipe, and an internal space of the housing is filled with high-pressure gas. And a bellows for partitioning into a liquid chamber communicating with the port hole. The bellows has a fixed end fixed to the oil port and a free end, and a bellows cap at the floating end. An accumulator in which an inner peripheral side is a liquid chamber, and a seal is provided on the inner surface of the oil port to close the liquid chamber at the time of zero-down and confine a part of the liquid in the liquid chamber. It has a pressure difference adjustment mechanism that reduces the pressure difference that occurs when the liquid confined in the gas and the sealed gas thermally expand. The adjustment mechanism includes a movable plate supported by a rubber-like elastic packing on the oil port 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. The communication path includes a through hole provided in the movable plate, and the movable plate moves with the bellows cap while being supported by the packing during steady operation, and the movable plate is Moves together with the bellows cap to contact the seal, and when the liquid and the filled gas are thermally expanded, the movable plate remains in contact with the seal and the bellows cap compresses the packing to a position where the liquid pressure and the gas pressure are balanced. It is characterized by moving while.

  The accumulator according to claim 2 of the present invention is the accumulator according to claim 1, wherein the accumulator according to claim 1 has a three-dimensional structure that acts as a spacer on one or both of the bellows cap that moves together and the opposing surface of the movable plate during steady operation. It is characterized by providing.

  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 movable plate is separated from the seal by moving with the bellows cap while being supported by the packing, 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 the bellows contracts due to the enclosed gas pressure, and the bellows cap moves in the bellows contraction direction. Since the movable plate is disposed on the oil port side of the bellows cap, the movable plate contacts the seal. When the movable plate 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. In addition, since it is a movable plate that contacts the seal and the bellows cap does not contact the seal, the pressure receiving area of the bellows cap is not limited by the seal. Therefore, the pressure receiving area of the bellows cap is set to be equal between the gas chamber side on one side and the liquid chamber side on the opposite side.

During thermal expansion in a zero-down state ...
When the liquid confined in the liquid chamber and the enclosed gas are thermally expanded due to an increase in ambient temperature in the zero down state, i.e., when the movable plate is in contact with the seal, the liquid has a greater pressure rise than the gas, so the pressure difference is greater. appear. Here, in the present invention, since the pressure receiving area of the bellows cap is set to be equal on the gas chamber side and the liquid chamber side as described above, the bellows cap immediately moves while compressing the packing when a pressure difference occurs, and the pressure difference Reduce. 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. The packing is provided for returning the bellows cap when the pressure drops.

  In this thermal expansion operation, the movable plate is subjected to the restriction of the pressure receiving area by the seal instead of the conventional bellows cap, so that it does not move away without touching the seal. Therefore, only the bellows cap moves while compressing the packing. During this thermal expansion operation, part of the liquid confined in the liquid chamber flows into the space between the bellows cap and the movable plate from the inner space of the bellows, but the packing interposed between the bellows cap and the movable plate is Since the sealing action is provided in addition to the spring action, the liquid is not allowed to pass therethrough. Therefore, it is necessary to separately provide a liquid communication path. Therefore, in the present invention, a through hole is provided in the movable plate and this is used as a communication path.

  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.

  In addition, when a three-dimensional structure that acts as a spacer is provided on one or both of the opposing surfaces of the bellows cap and the movable plate, it is difficult for the two to be in close contact with each other because the liquid easily flows between the two. Therefore, the relative movement of both during the thermal expansion operation can be smoothed.

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 disc (movable plate) supported by rubber (elastic body) is provided on the oil port side of the bellows cap. At the time of zero-down, this disk comes into contact with a seal provided in the oil port, and prevents the liquid inside the bellows from flowing out.
(2) Since it is sealed by the disk at the time of zero down, the pressure receiving area of the gas pressure in the bellows cap and the liquid pressure inside the bellows becomes equal. Since the disc is fixed to the bellows cap via a rubber O-ring, square ring or V-ring (packing), the bellows cap is within a certain range even when the disc is pressed onto the oil port. Can move up and down freely. When the liquid inside the bellows is thermally expanded, the bellows cap can be moved to a position where the gas pressure and the liquid pressure are balanced while the disc is pressed against the oil port. The bellows is not deformed.
(4) The shape of the disc and bellows cap is such that the cylindrical surface is tapered so that it can move smoothly even when the disc and bellows cap are relatively tilted. Protrusions that prevent adhesion of the lower surface of the cap are provided on the upper surface of the disk or the lower surface of the bellows cap.
(5) When using rubber (elastic body), the liquid cannot pass through the part where the rubber is mounted. Therefore, a communicating hole is provided in the movable plate, and oil is passed between the disc and the bellows cap via this communicating hole. To flow into.

  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 by a rubber-like elastic packing 23 that has an annular shape on the oil port 4 side of the bellows cap 8, a bellows 7, the oil port 4, the movable plate 22, A space (bellows inner circumferential space) 11a surrounded by the packing 23 and the bellows cap 8 and a communication passage 24 for communicating the space 11b between the bellows cap and the movable plate are provided. On the surface of the bellows cap 8 on the oil port 4 side (the lower surface in the figure, also referred to as the lower surface in the following), there is a recess 8a that accommodates the movable plate 22, and the movable plate 22 can be moved relative to the recess 8a. Contained. An annular packing receiver 25 is provided on the lower surface of the bellows cap 8 and around the recess 8a. Between the stepped engagement portion 22a provided on the outer peripheral portion of the movable plate 22 and the packing receiver 25, a packing 23 made of an O-ring, a square ring or a V-ring (O-ring in the figure) is interposed. Therefore, the movable plate 22 is held by the bellows cap 8 via the packing receiver 25 and the packing 23 while being accommodated in the recess 8a provided on the lower surface of the bellows cap 8. The movable plate 22 and the bellows cap 8 are Relative displacement in the axial direction is possible within a range in which 23 contracts. Normally, a predetermined axial gap c is provided between the lower surface (the bottom surface of the recess) of the bellows cap 8 and the surface of the movable plate 22 on the side of the bellows cap 8 (upper surface in the figure, hereinafter also referred to as the upper surface). Although it is set, a structure in which both surfaces come into contact with no gap may be employed.

  The movable plate 22 is made of a disc made of a rigid material such as metal, and is in contact with or separated from the seal 13. The movable plate 22 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 movable plate 22 is already in contact with the seal 13 when the movable plate 22 contacts the stopper projection 4a.

  The communication path 24 has a radial groove 4d provided on the end surface (upper surface) of the stopper projection 4a and a through hole 22b provided in the movable plate 22. The radial groove 4d is formed so as to penetrate the stopper protrusion 4a in the radial direction and communicate with the inner space 11a of the bellows and a space (seal outer space) 11c surrounded by the stopper protrusion 4a, the seal 13 and the movable plate 22. ing. A plurality of the radial grooves 4d are provided side by side with a predetermined interval in the circumferential direction of the stopper projection 4a. The through hole 22b is formed so as to penetrate the movable plate 22 in the plate thickness direction and communicate the seal outer peripheral space 11c with the space 11b between the bellows cap 8 and the movable plate 22. A plurality of the through holes 22b are provided side by side in the circumferential direction of the movable plate 22 with a predetermined interval.

  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 movable plate 22 is separated from the seal 13 by moving together with the bellows cap 8 while being supported by the packing 23, so the port hole 5 and the liquid chamber 11 (the space between the bellows 7 and the seal 13). Are communicating. 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 movable plate 22 so that the liquid pressure and the gas pressure are balanced.

Zero down ...
When the operation of the device 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 contracted by the bellows. Move gradually in the direction. Since the movable plate 22 is disposed on the oil port 4 side of the bellows cap 8, the movable plate 22 contacts the seal 13 when the bellows cap 8 moves. As shown in FIG. 2, the movable plate 22 stops by contacting the stopper projection 4a, and the bellows cap 8 also stops. When the movable plate 22 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 movable plate 22 contacts the seal 13 and the bellows cap 8 does not contact. Therefore, the pressure receiving area of the bellows cap 8 is not limited by the seal 13 as in the prior art. Therefore, the pressure receiving area of the bellows cap 8 is set to be equal between 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 ...
When the liquid confined in the liquid chamber 11 and the sealed gas are thermally expanded due to an increase in the ambient temperature in the zero down state of FIG. 2, that is, the movable plate 22 is in contact with the seal 13 and the stopper projection 4a, 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 bellows cap 8 is set to be equal between the gas chamber 10 side and the liquid chamber 11 side, the bellows cap 8 compresses the packing 23 as shown in FIG. However, it immediately starts moving away from the movable plate 22 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, since the movable plate 22 remains in contact with the seal 13 as shown in the figure due to the difference in pressure receiving area between the upper and lower surfaces, the zero-down state is not eliminated. The liquid in the bellows inner peripheral space 11a flows into the space 11b between the bellows cap 8 and the movable plate 22 through the communication passage 24, that is, the radial groove 4d, the seal outer peripheral space 11c, and the through hole 22b.

  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.

  2, the radial groove 4d provided at the tip of the stopper projection 4a has a function of communicating the seal outer peripheral space 11c with the bellows inner peripheral space 11a, and is provided on the movable plate 22. The through-hole 22b has a function of communicating the seal outer peripheral space 11c with the space 11b between the bellows cap 8 and the movable plate 22, thereby suppressing an increase in pressure due to thermal expansion of the liquid in the seal outer peripheral space 11c. Accordingly, it is possible to prevent the seal 13 from being damaged due to the high pressure in the seal outer peripheral space 11c.

  Furthermore, it is conceivable to add / change the configuration of the accumulator 1 according to the above embodiment as follows.

(1) The packing 23 in the above embodiment is interposed between a stepped engagement portion 22a provided on the outer peripheral portion of the movable plate 22 and the packing receiver 25. It is set not to contact the outer peripheral surface and the inner peripheral surface of the bellows cap 8 (the inner surface of the recess 8a). On the other hand, when the packing 23 is always brought into contact with the outer peripheral surface of the movable plate 22 and the inner peripheral surface of the bellows cap 8 (the inner peripheral surface of the recess 8a), the packing 23 is connected to the movable plate 22 and the bellows cap 8. The function of aligning and (the function of always keeping the same core) can be exhibited.

(2) As shown in the respective drawings of FIG. 4, the cylindrical surfaces of both plates 22 and 22 (the outer peripheral surface of the movable plate 22) so that the movable plate 22 and the bellows cap 8 are relatively inclined even when they are relatively inclined. The tapered shape 27 is provided on the inner peripheral surface of the recess 8a of the bellows cap 8. Each taper is inclined to the oil port 4 side from the inner diameter side to the outer diameter side.

(3) The movable plate 22 and the bellows cap 8 are placed on either one or both of the opposing surfaces of the two 8, 22 as shown in each drawing of FIG. Provide a three-dimensional structure that acts as a spacer.

  In the example of FIG. 4A, a projection 28 is provided in the center of the plane of the lower surface of the bellows cap 8 (the bottom surface of the recess 8a), and a gap space 29 is set on the outer peripheral side (around) of the projection 28. In the example of FIG. 4B, a protrusion 28 is provided at the center of the upper surface of the movable plate 22, and a gap space 29 is set on the outer peripheral side (around) of the protrusion 28. In the example of FIG. 4C, an annular protrusion 28 is provided on the peripheral edge of the lower surface of the bellows cap 8 (the bottom surface of the recess 8 a), and a gap space 29 is set on the inner peripheral side of the protrusion 28. In order to allow liquid to flow into the gap space 29 on the inner peripheral side of the protrusion 28, a groove or a notch-shaped flow path (not shown) extending in the radial direction is provided on a part of the periphery of the protrusion 28. (However, since the liquid flows from the through hole 22b, there is no need for a flow path). In the example of FIG. 4D, an annular protrusion 28 is provided on the peripheral edge of the upper surface of the movable plate 22, and a gap space 29 is set on the inner peripheral side of the protrusion 28. In order to allow liquid to flow into the gap space 29 on the inner peripheral side of the protrusion 28, a groove or a notch-shaped flow path (not shown) extending in the radial direction is provided on a part of the periphery of the protrusion 28. (However, since the liquid flows from the through hole 22b, there is no need for a flow path).

  According to the above configuration, even if the bellows cap 8 and the movable plate 22 are in contact with each other, the liquid easily flows between the both. Accordingly, the two and 22 are less likely to be in close contact with each other, and the relative movement of the two and 22 during the thermal expansion operation can be facilitated.

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 (A) (B) (C) And (D) sectional drawing which shows the example which provided the three-dimensional structure in the movable plate or the bellows cap 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 4d Radial groove 5 Port hole 7 Bellows 7a Fixed end 7b Free end 8 Bellows cap 8a Concave 9 Damping ring 10 Gas chamber 11 Liquid chamber 11a, 11b 11c Space 13 Seal 14 Seal holder 21 Pressure difference adjustment mechanism 22 Movable plate 22a Engagement part 22b Through hole 23 Packing 24 Communication path 25 Packing receiver 27 Taper shape 28 Projection 29 Gap space

Claims (2)

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 includes a movable plate supported by a rubber-like elastic packing on the oil port 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. And the communication path includes a through hole provided in the movable plate,
At the time of steady operation, the movable plate moves with the bellows cap while being supported by the packing, and at the time of zero down, the movable plate moves with the bellows cap and contacts the seal, and heat of the liquid and the enclosed gas The accumulator is characterized in that, when expanded, the movable plate moves while compressing the packing to a position where the liquid pressure and the gas pressure are balanced while the movable plate is in contact with the seal. The accumulator according to claim 1, wherein
An accumulator characterized in that a three-dimensional structure that acts as a spacer is provided on one or both of a bellows cap that moves together during normal operation and an opposing surface of the movable plate.

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