JP2005325931A - Piston type accumulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston type accumulator which has a simple construction, hardly contaminates under several kinds of used conditions, and has high functionability. <P>SOLUTION: The piston type accumulator is provided with an outer case 1, a piston 2 slidably fitted in the outer case 1, demarcating an outer case 1 inside into a liquid chamber 3 and a gas chamber 4, a liquid sealing means 9 arranged in a liquid chamber 3 side of the piston 2 periphery, a gas sealing means 10 arranged in a gas chamber 4 side of the piston 2 periphery, and a partition chamber 5 comprised of the outer case 1 inside, the outer case 2 outside, the liquid sealing means 9 and the gas sealing means 10. A purge inlet 6 and a purge outlet 7 to purge the partition chamber 5 are provided to detect the pressure in the partition chamber 5 of the introduced purge fluid and control so as to maintain the pressure lower than at least either of the liquid chamber 3 or the gas chamber 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an accumulator, and more particularly to a piston type accumulator for the purpose of accumulating and buffering an incompressible fluid typified by a liquid.

  In general, in an incompressible hydraulic circuit typified by oil or water, an accumulator is used to buffer the piping system by storing or deriving a part of the flowing liquid. Hereinafter, in order to simplify the description, a state having poor compressibility is referred to as “liquid”, and a state having high compressibility is referred to as “gas”.

  For example, when the actuator is locked by receiving an external force such as a brake mechanism of an automobile and the hydraulic actuator that drives the actuator becomes inoperable, the pressure of the hydraulic oil sent to the actuator increases excessively. In this case, if the accumulator is provided in the hydraulic circuit, a part of the hydraulic oil is temporarily introduced into the accumulator, so that an excessive pressure increase can be avoided and the safety of the hydraulic circuit can be ensured. On the other hand, when the actuator is unlocked, before the hydraulic oil from the hydraulic pump is supplied to the actuator, the hydraulic oil accumulated in the accumulator is first derived so that the actuator operates quickly. The operating pressure can be assisted.

There are various types of accumulators, such as a bladder type, piston type, and diaphragm type. Usually, a bladder type accumulator in which a gas-filled rubber bladder is built in a shell and a cylinder are defined by a piston 2. A piston type accumulator in which gas is sealed in one of the two chambers is often used. The pressure of the inert gas sealed in the bladder or the gas chamber varies depending on the purpose of use, but is, for example, about 70 kgf / cm ² under the initial conditions, and the bladder contracts or displaces when the working fluid enters the accumulator. When the piston is compressed, the maximum is about 210 kgf / cm ² . On the other hand, when the pressure of the hydraulic fluid decreases, the gas expands, and the hydraulic fluid inside the accumulator is returned to the hydraulic circuit.

Specifically, a structure as shown in FIG. 3 is conventionally known as a piston-type accumulator. A piston 102 is slidably housed in a bottomed cylindrical outer case 101, O-rings 103, 103 and the like are fitted on the outer periphery of the piston 102, and a plug 104 is fixed to the opening 105 of the outer case 101. Further, nitrogen gas is sealed in the gas chamber S1 and sealed with a plug bolt 106, and the liquid chamber S2 is filled with hydraulic oil. In this accumulator, the outer case 101 and the plug 104 are fixed by welding the opening 105 of the outer case 101 (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 08-296601

  However, in the accumulator as described above, the leakage through the seal part of the outer periphery of the prada or piston cannot be avoided, and in space development related devices, chemical reaction devices, semiconductor devices, supercritical fluid supply devices, etc. In this case, contamination of hydraulic fluid becomes a problem.

  In particular, the former is caused by the large area of the bladder involved in permeation, and the latter involves the attachment / adsorption of working fluid and gas to the inner wall of the outer case or contamination from outside air as the piston moves. .

  Also, even if a metal bellows type or diaphragm type is used instead of the bladder type or piston type, the problem of contamination can be solved by the metal material, but the higher the pressure, the thicker the wall, Difficulty in obtaining a large-capacity accumulator and short life due to metal fatigue due to cyclic stress are problems. Furthermore, in addition to being expensive per se, there are problems in terms of maintenance work and cost.

  An object of the present invention is to provide an accumulator having high functionality that keeps costs low with a simple structure and hardly contaminates even under such use conditions.

  The present invention includes (1) an outer case, (2) a piston that is slidably fitted in the outer case, and that partitions the inside of the outer case into a liquid chamber and a gas chamber, and (3) the piston Liquid sealing means disposed on the liquid chamber side of the outer periphery, (4) gas sealing means disposed on the gas chamber side of the outer periphery of the piston, and (5) inner surface of the outer case, piston outer surface, liquid sealing means, and A piston-type accumulator having a compartment formed by a gas sealing means, provided with an inlet and an outlet for purging the compartment, and detecting the pressure of the introduced purge fluid inside the compartment, Control is performed to maintain a lower pressure than at least one of the chamber and the gas chamber.

  In other words, the liquid chamber and the gas chamber are partitioned by the compartment, so that direct mutual contact and contact with the outside air can be avoided. The influence of outside air can be blocked. As a result, even if there is a leakage of working fluid or gas unavoidable due to the structure of the accumulator as described above, contamination of the working fluid can be prevented.

  The pressure in the compartment is preferably the same as that in the liquid chamber or gas chamber to suppress leakage from the liquid chamber and gas chamber, but the pressure in the actual hydraulic circuit may fluctuate very quickly. Yes, and pressure control that follows this is very difficult. Therefore, by operating at a pressure lower than that of either the liquid chamber or the gas chamber, and particularly controlling the difference to be small, operation under ideal conditions is possible.

  Furthermore, it is also preferable to provide two or more purge inlets and purge outlets at a portion of the compartment close to the liquid chamber and a portion of the gas chamber, and to purge separately, and in particular, the compartments are divided into two or more, each having a different pressure or The purge effect can be further increased by the fluid.

  The present invention also includes (1) a plurality of outer cases, and (2) slidably fitted in the outer cases, and partitioning at least two of a liquid chamber, a gas chamber, a compartment, and outside air. (3) at least one sealing means disposed on the outer periphery of each piston; and (4) at least one compartment formed by a pair of the outer case inner surface, the piston outer surface and the sealing means; 5) A piston type accumulator comprising a coupling means for coupling the pistons to each other, wherein an inlet and an outlet for purging the compartment are provided, and the pressure inside the compartment of the introduced purge fluid is detected, Control is performed to maintain a lower pressure than at least one of the liquid chamber and the gas chamber.

    The accumulator utilizes the fact that the compressibility is greatly different between the liquid chamber and the gas chamber, and transmits the pressure change on the liquid chamber side to the gas chamber side as it is by means of the piston, thereby making use of functions such as pressure accumulation or buffering. However, depending on the use of the accumulator, there are cases where it is desired to adjust the compression ratio or the distance between the two chambers. For the former, the piston provided in the outer case having the liquid chamber is connected to the piston provided in the outer case having the gas chamber, and the pressure receiving areas on the liquid chamber side and the gas chamber side are different. Is possible.

  For the latter, there is a case where an accumulator that is short in the axial direction and long in the radial direction is preferable or reverse, or the shape of the liquid chamber and the gas chamber may be different from each other. With the configuration having the outer case, it is possible to provide a highly versatile accumulator that can be applied to such a request for proper use.

  The present invention is the above piston-type accumulator, characterized in that the purge fluid is the same component as any component in the liquid chamber or the gas chamber.

  As described above, the purge fluid does not directly enter each liquid chamber or gas chamber if the pressure in the compartment into which the purge fluid is introduced is maintained at a pressure lower than that of the liquid chamber or gas chamber. However, when the temperature of the liquid chamber or gas chamber is low, there is a possibility that the piston fluid moves or gets mixed into the liquid chamber or gas chamber due to adhesion or adsorption to the inner wall of the outer case due to liquefaction or high density of the purge fluid. It cannot be said that there is no. At this time, such an impurity is obtained by providing a fluid inlet and outlet at a part of the compartment close to the liquid chamber or a part of the gas chamber and purging with a fluid having the same component as any of the components in the liquid chamber or the gas chamber. The purge effect can be further enhanced.

  As described above, by improving the purge function of the compartment provided between the liquid chamber and the gas chamber, it is possible to provide a highly functional accumulator that hardly causes contamination. Further, by devising not only the purge mechanism but also the piston and the outer case, the pressures of the liquid chamber and the gas chamber can be operated with different values. Therefore, it is possible to provide an accumulator having high functionality that keeps the cost low with a simple configuration and hardly contaminates even under such use conditions.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration (first configuration example) of an accumulator according to the present invention, and an embodiment including a cylindrical outer case 1 and a piston 2 will be described. However, the accumulator of the present invention is not limited to this, and various modifications can be made according to the purpose.

  Specifically, the outer case 1 is divided by a piston 2, a liquid chamber 3 provided on one side, a gas chamber 4 provided on the other side, an inner surface of the outer case 1, an outer peripheral surface of the piston 2, a liquid and a gas. An accumulator is formed from the compartment 5 formed by the sealing means 9 and 10. The compartment 5 is purged continuously or intermittently with a purge fluid. The purge fluid is introduced from the purge inlet 6 and discharged from the purge outlet 7, and is monitored by a pressure gauge 8 provided on the purge outlet 7 side, and is controlled at a predetermined pressure by a pressure adjusting means (not shown). The The liquid chamber 3 and the compartment 5 are partitioned by the sealing means 9, and the gas chamber 4 and the compartment 5 are partitioned by the sealing means 10. In addition, the compartment 5 can also provide a recessed part in the outer peripheral surface of the piston 2, the inner peripheral surface of the outer case 1, or can provide a recessed part in both.

  One end of the accumulator is connected to the working fluid via the liquid connecting part 11, and the other end is connected to a gas supply means or a gas sealing means (not shown) via the gas connecting part 12. At this time, for example, when the pressure of the hydraulic fluid rises, the pressure of the liquid surface 2a of the piston 2 is increased to move the piston 2, and the gas enclosed in the gas chamber 4 is compressed to increase the pressure. On the contrary, when the pressure of the hydraulic fluid is reduced, the pressure on the liquid surface 2a of the piston 2 is reduced to move the piston 2, and the gas enclosed in the gas chamber 4 is expanded to reduce the pressure. As a result, the accumulator pressure or buffering function functions.

  At this time, a slight amount of hydraulic fluid and gas leaking into the compartment 5 that divides the liquid chamber 3 and the gas chamber 4 are quickly eliminated by the purge fluid, thereby blocking the mutual influence or the influence of the outside air. . In particular, by controlling the pressure of the purge fluid in the compartment 5 to be lower than that of either the liquid chamber 3 or the gas chamber 4 and keeping the difference small, it is possible to significantly reduce leakage. It becomes.

  In addition, the purge fluid is preferably the same component as any component in the liquid chamber 3 or the gas chamber 4. That is, it is possible to prevent the liquid chamber 3 or the gas chamber 4 from being contaminated by the reverse diffusion of the purge fluid. In addition, when the temperature of the liquid chamber 3 or the gas chamber 4 is low, the liquid chamber 3 that accompanies the movement of the piston, which may be caused by adhesion or adsorption to the inner wall of the outer case 1 due to liquefaction or high density of the purge fluid. Or mixing into the gas chamber 4 can be prevented.

  Here, the piston 2 preferably forms a cylindrical body having a wall surface on the liquid chamber 3 side in order to ensure a large volume inside the gas chamber 4. Moreover, although the sealing means is illustrated as a packing-like body in FIG. 1, specifically, various structures such as an O-ring and a Y-ring can be applied.

  Another embodiment of the present invention is illustrated in FIG. 2 (second configuration example). In the piston type accumulator, the piston 2 a built in the outer case 1 a on the liquid chamber 3 side, the gas chamber 4 side, and the piston 2 b built in the outer case 1 b are connected by the connecting means 13. Each outer case 1a and 1b includes an inner surface of the outer case 1a, an outer peripheral surface of the piston 2a, a compartment 5a formed by the liquid sealing means 9a and 9b, an inner surface of the outer case 1b, and an outer peripheral surface of the piston 2b. A compartment 5b formed by the gas sealing means 10a and 10b is provided, and is purged continuously or intermittently by the purge fluid. Purge fluid is introduced from purge inlets 6a and 6b and discharged from purge outlets 7a and 7b, respectively.

  Note that the periphery of the connecting means 13 does not require any particular purging, and in FIG. 2, the compartment 14 is in a state of communicating with the outside air, but is not limited thereto. Instead of the compartment 14, the compartment 5a and the compartment b are adjacent to each other, and a common sealing means is used instead of the liquid sealing means 9b and the gas sealing means 10b at the center, and the compartment purge outlet 7a and A method of discharging each purge fluid from 7b (not shown), or a method of providing a common purge outlet 7 without providing purge outlets 7a and 7b and sealing means 9b and 10b in the outer cases 1a and 1b ( (Not shown).

  At this time, as shown in FIG. 2, when the pressure receiving area 2 a of the piston 2 a is smaller than the pressure receiving area 2 b of the piston 2 b, the hydraulic fluid pressure is transmitted by the pistons 2 a and 2 b through the liquid chamber 3. And works to maintain an equilibrium relationship with the internal pressure of the gas chamber 4. That is, the internal pressure of the gas chamber 3 can be balanced in a state lower than the internal pressure of the liquid chamber 4.

  Conversely, when the pressure receiving area 2a on the liquid chamber 3 side is larger than the pressure receiving area 2b on the gas chamber 4 side, the internal pressure of the gas chamber 3 can be balanced in a state higher than the internal pressure of the liquid chamber 4.

  That is, the pressure of the gas chamber 3 is preferably within a predetermined range in order to make its pressure accumulation / buffer function work effectively, and the outer case 1a and the piston 2a or the outer case 1b according to the conditions of the hydraulic fluid. By selecting the piston 2b, the pressure of the gas chamber 3 can be set within an optimum range, and the fine pressure fluctuation of the hydraulic fluid can be absorbed and accumulated more accurately.

  In the second configuration example described above, the piston 2a fitted in the outer case 1a having the liquid chamber 3 and the piston 2b fitted in the outer case 1b having the gas chamber 4 are connected. However, it goes without saying that the present invention is not limited to such a configuration. Specifically, a plurality of these are arranged in parallel, a configuration in which purge fluid is introduced into each compartment 5, and a plurality of pistons 2b on a piston 2a fitted into an outer case 1a having one liquid chamber 3, Are connected in series or in parallel, and the pistons 2b, 2c,... Are fitted in outer cases 1b, 1c,. The former is excellent in that the accumulator function can be distributed in the order of the flow paths in response to the fluctuation of the hydraulic fluid, and the latter can disperse the load of the gas chamber 4 in the accumulator.

  As described above, the usage of the accumulator extends over many branches. In the present application, the basic usage method is described. However, it is obvious that the present invention can be applied in many cases by combining with various technologies, and has high versatility.

  Further, the present invention is not limited to the combination of “liquid” and “gas” in the narrow sense as defined above, and can be used in a wider range. For example, the liquid chamber of the present invention can be connected to a flow path of a low-temperature supercritical pressure fluid with poor compressibility and used for pressure accumulation and buffering. Moreover, as long as it is a fluid rich in compressibility, it can be accommodated not only in gas but in the gas chamber of the present invention and used as a buffer fluid.

Explanatory drawing which shows the 1st structural example of the accumulator which concerns on this invention. Explanatory drawing which shows the 2nd structural example of the accumulator which concerns on this invention. Explanatory drawing illustrating a conventional configuration

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer case 2 Piston 3 Liquid chamber 4 Gas chamber 5, 14 Compartment 6 Purge inlet 7 Purge outlet 8 Pressure gauge 9 Liquid seal means 10 Gas seal means 11 Liquid connection part 12 Gas connection part 13 Connection means

Claims (3)

  (1) an outer case, (2) a piston that is slidably fitted in the outer case, and divides the outer case into a liquid chamber and a gas chamber, and (3) a liquid chamber around the piston. Liquid sealing means disposed on the side, (4) gas sealing means disposed on the gas chamber side of the outer periphery of the piston, and (5) the inner surface of the outer case, the outer surface of the piston, the liquid sealing means, and the gas sealing means. A piston-type accumulator having a compartment formed therein, an inlet and an outlet for purging the compartment, and detecting a pressure in the compartment of the introduced purge fluid, and a liquid chamber or a gas chamber The piston type accumulator is controlled so as to maintain a pressure lower than at least one of the above.   (1) a plurality of outer cases, (2) a piston that is slidably fitted in each outer case and divides at least two of a liquid chamber, a gas chamber, a compartment, and outside air; ) Sealing means disposed on at least one outer periphery of each piston; (4) at least one compartment formed by a pair of the outer case inner surface, piston outer surface and sealing means; A piston-type accumulator comprising: a coupling means for coupling the chamber; and an inlet and an outlet for purging the compartment, and detecting a pressure in the compartment of the introduced purge fluid, and a liquid chamber or a gas chamber The piston type accumulator is controlled so as to maintain a pressure lower than at least one of the above. The piston-type accumulator according to claim 1 or 2, wherein the purge fluid is the same component as that of either the liquid chamber or the gas chamber.

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