GB2060071A

GB2060071A - Pulsation Absorption Device for High Pressure Liquid

Info

Publication number: GB2060071A
Application number: GB7935456A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-10-12
Filing date: 1979-10-12
Publication date: 1981-04-29
Also published as: GB2060071B

Abstract

Pulsation absorption device comprising a pressure vessel, a bladder 5 housed in the pressure vessel, liquid incoming and outgoing pathes formed by concentric cylinders placed under the pressure vessel, a valve system for opening and closing said liquid incoming and outgoing pathes, said valve system includes a dash pot 31 for slowly opening and closing a valve body whereupon the valve body is controlled from being abruptly moved with rapid streaming speed of high pressure liquid or pressure variation thereby the function of pulsation absorption is more enhanced and any trouble and damage to the pressure accumulator system is avoided. <IMAGE>

Description

SPECIFICATION Pulsation Absorption Device for High Pressure Liquid This invention relates to a pulsation absorption system for high pressure liquid connected to hydraulic piping or the like.

Generally pressure liquid ejected from the hydraulic system, particularly from pumps accompanies pulse and such pulse renders undesirable effects to the whole system.

For absorbing pulses of this kind, a pressure accumulator is generally used. However with this, the highest frequency of pulse liquid that has been enabled to absorb numbers only one hundreds cycles. For absorbing pulses of several hundreds cycles, it is not possible to absorb with such accumulator.

Japanese Patent Nlo. 479,913 (Patent Publication No. SHO 41-5789) teaches that it is possible to absorb pulse amounting to several hundreds cycles by providing a liquid incoming path from the pump piping to the liquid chamber of a pressure vessel with a bladder housed therein and separately providing a liquid outgoing path from said liquid chamber to piping of various loading devices. Thus, it is said, pulse to be delivered from the piping to the bladder can be absorbed.

Also this patent teaches that it is possible to deliver pressure liquid from outer piping to the liquid chamber for uniformly working to the whole circumference of the bladder by forming a liquid incoming path and outgoing path with dual piping for incoming and outgoing liquid thereby contraction and expansion of the bladder is smoothly perFsnnsd without any eccentricity and also by providing valve means to liquid incoming path and outgoing path respectively, the bladder is preveni 7a' from being caught in the liquid incomin and outgoing paths, thus the bladder is protected fwom being locally injured.

However, the pulse absorbing device of this Japanese Pasent is able to perform its pulse absorbing function for applying to the hydraulic circuit in which liquid flowing speed is 7 m/sec or less. Thel efore it is not possible to apply to the hydraulic circuit of today in which liquid flowing speed is 7 m/sec or higher. Because if the liquid flowing speed becomes faster, the valve body tends to become turbulent as it is affected by flowing speed. Particularly when the side of liquid outgoing path is non-loaded, its side becomes to negative pressure and its path will be interrupted.

Therefore, one object of the present invention is to avoid the valve body from being opened or closed abruptly due to pressure liquid flowing with high speed.

Another object of the present invention is to provide a pulse absorption device that is able to absorb pulse of several hundreds cycles completely.

Still another object of the present invention is to provide a pulse absorption device that is able to effectively absorb pulse.

The pulse absorption system of the present invention consists of a pressure vessel, bladder housed in the pressure vessel, valve means for opening and closing the liquid incoming and outgoing paths formed by dual cylinders under the pressure vessel and by providing a dash pot for slowing down the opening and closing the valve body, thus a unique pulse absorbing for high pressure liquid is accomplished.

Other objects and features of the present invention will be better understood as description proceeds with reference to accompanying drawings in which: Fig. 1 is a longitudinal cross-section view of one embodiment of the present invention.

Fig. 2 is a detailed cross-section view of the essential part of Fig. 1. Fig. 2a is an enlarged view of the essential part of Fig. 2.

Fig. 3-8 are, each cross-section view of embodiments in which a valve body is supported with a guide member consisting of dual cylinders.

Fig. 3 is a cross-section view of an essential part of an example in which a dash pot is formed with an inner duct and inner cylinder of guide member.

Fig. 3a is an enlarged view of the dash pot portion of Fig. 3.

Fig. 4 is a cross-section view of an essential part of one embodiment in which a dash pot is formed with an outer cylinder of guide member and outer coupling. Fig. 4a is an enlarged view of the dash pot in Fig. 4.

Fig. 5 is a cross-section view of an essential part similar to that in Fig. 4.

Fig. 6 is a cross-section view taken along the line VI-Vi in Fig. 5.

Fig. 7 is a cross section view of an essential part of a modification of that in Fig. 4.

Fig. 8 is a cross section view taken along the line VIll-VIll in Fig. 7.

Fig. 9 is a cross-section view of an essential part of an example of a modification of guide member for the valve body.

Fig. 10 is a crnss-section view of an essential part of an example of valve system with an inner valve body for inlet path of pressure liquid and an outer valve body for the side of outgoing liquid path.

Fig. 11 is a cross-section of an essential part showing that the inside valve shown in Fig. 10 is mounted to the bottom of the bladder.

Fig. 12 is a cross-section view of an essential part of an example in which a valve body having a guide cylinder is mounted to the bottom of the bladder.

Fig. 13 is a cross-section view of an essential part of an example in which a valve body is mounted to the bottom of the bladder and a guide cylinder is attached to the inner duct.

Fig. 14 is oscillographic wave comparing the effect of pulse absorption. (a) shows wave of pulse generated in the hydraulic system. (b) shows wave in the case where piping of hydraulic system accompanying pulse as in (a) is associated to a general accumulator. The upper graph shows pulse wave in the side of liquid inlet and the lower graph shows that in the side of liquid outlet side.

(c) shows wave in the case where pulse absorbing device of the present invention is associated to said hydraulic system. The upper graph shows the pulse wave in the side of inlet and lower graph shows in the side of outlet.

Referring now to Fig. 1, numeral 1 generally designates a pressure vessel made of metal appropriate to pressure applied. This vessel is formed of a cylindrical body 2 with an upper end 3 and lower end 4, each semispherically shaped.

5 is a bladder made of natural or synthetic rubber shaped after the pressure vessel 1. 6 is an upper opening through which the bladder 5 is inserted in the pressure vessel 1. The top periphery of the bladder 5 is formed to a flange 7 which is placed and supported on the step portion 8 formed along the upper inner wall of the pressure vessel 1. On this flange 7, a protector ring 9 is closedly placed, which ring is downwardly extended as a skirt over the inner periphery of the flange 7 and its bottom is rolled back to form an annular tube.Thus this protector ring 9 prevents the bladder from being injured by its sharp bending when it floats upward with liquid pressure and at the same time, this ring serves as a packing for this flange portion 8 of the bladder 11 is a lid metal on the flange 7 and tightened with a ring nut 12 threadedly screwed in the opening 6. 13 is a gas port provided in the lid metal 11 through which nitrogen gas is supplied into the bladder 5.

Thereby a gas chamber 14 formed in the bladder is pressurized with liquid flowing into a liquid chamber 15 in the vessel.

16 is a cylindrical coupling secured to the bottom of the pressure vessel 1 with a ring nut 1 7. 18 is a base cylinder connected to the lower end of said coupling 16. 19 is an inner duct concentrically provided in the coupling 16 for incoming liquid. In the annular space between this inner duct 19 and coupling 16, an outgoing liquid path is formed. As shown in Fig. 2, this inner duct 19 is consisted of a lower elbow duct 20 and an upper duct 22 having enlarged portion 21. In the upper duct 22, a valve stem casing 24 is supported with a plurality of arms 23.

A valve body 25 is slidably supported relative to the inner duct 19 as its valve stem 26 is inserted in said valve stem casing 24 and with the force of a spring 27, it is held in the position in Fig. 2 when non-loaded. When the valve body 25 is subjected to a downward force, this valve body 25 is seated on the seat 28 formed on the top inner periphery of the cylindrical coupling 16.At the lower end of the valve stem 26, a piston 29 is inserted in a cylinder portion 30 to form a dash pot 31 (Fig. 2a). As shown in Fig. 2, this dash pot 31 functions when the valve body 25 is in a position to be pushed upward with the force of spring 37 and when an instantaneous abrupt closing downward force is imparted to the valve body 25, its speed is lowered thereby the valve body 25 is slowly moved. 32 is an inlet for pressure liquid. 33 is an outlet of pressure liquid.

34 is a bladder receiving cup attached to the valve body 25.

In Fig. 3 and Fig. 3a, instead of the valve stem 26 slidingly guides the valve body 25 of Fig. 2, there is shown another guide member 35 consisting of double cylinders.

This guide member 35 is consisting of an inner cylinder 36 the top end of which is attached to the valve body 25 and slidably engaged with its inner duct 19 and an outer cylinder 37 slidable along the inside of the coupling 16. These inner and outer cylinders 36, 37 are integrally connected with a plurality of arms 38 spanned therebetween. The upper portion of the inner cylinder 36 is provided a plurality of apertures 39.

The lower end of it is formed an inwardly stepped portion 40 and with an outwardly stepped portion 41 formed at the top end of the inner duct 19, there is formed a dash pot 31. A spring 27 is interposed between a plurality of nails 42 formed on the innerwall of duct 19 and the neck portion of the valve 25 where the upper end of the inner cylinder 36 joints therewith.

Same parts having same numerals in this Figure with those in Fig.1 and 2 perform same function.

In Fig. 4 and Fig. 4a, an example is shown in which the top end of the outer coupling 16 is weldingly connected to the bottom of the pressure vessel 1 and the dash pot 31 is formed with the outer sliding cylinder 37 of the guide member 35 and outer coupling 76.

The inner diameter of the outer coupling 1 6 is made somewhat larger than the bottom opening 43 of the pressure vessel 1 and in the lower end periphery of the opening 43 is formed a step portion 43a. The top end of the outer cylinder 37 is formed a small diametered portion 44 to be abutted to the bottom of said step portion 43a, thus there is formed a dash pot 31 with the step portion 43a and small diametered portion 44.

The top end of the inner sliding cylinder 36 of guide member is provided with a hood plate 45 secured to the valve body 25 and the upper portion of this cylinder has a plurality of apertures 39. From the sides of the apertures 39, ribs 46 are extended. The lower portions of ribs 46 extend passing through the flared portion 47 and integrally joint with the small diametered portion 44 of the outer sliding cylinder 37. The liquid chamber 15 communicates through a passage 48 partitioned by under flared portion 47 and ribs 46 to an annular outlet path 49 between the inner duct 19 and outer coupling 16.

Fig. 5 shows a modification of the guide member 35 in the embodiment of Fig. 4. Instead of the flared portion 47 in Fig. 4, the inner sliding cylinder 36 and outer cylinder 37 are connected with a flange portion 50. In the flanged portion 50, flowing out ports 51 are bored as seen in Fig.

6. A spring 27 seats on the step portion 52 of the outer coupling 16 and the top end of it abuts the under side of the flanged portion 50. The same parts of same numerals in Fig.4~6 as those in Fig. 1-3 have same functions.

Examples shown in Figs. 7 and 8 are, each a modification of the guide member 35 and inner cylinder 19 of the embodiment of Fig. 3.

In this Figure, the dash pot 31 is formed, as in Fig. 3, with the step portion 41 of the inner duct 19 and the step portion 40 of the inner sliding cylinder 36. While the inner sliding cyinder 36 and outer sliding cylinder 37 are connected with the flanged portion 51 as like that in Fig. 3, the inner sliding cylinder 36 has an upwardly reduced portion 53 with which the valve body 25 is supported. In the circumferential periphery of this reduced portion 53, apertures 39 are bored. Other parts having same numerals in this Figure, with those in Fig. 1-6 have same functions.

Fig. 9 shows a modification of the example in Fig. 2. Therein the dash pot 31 is formed with the piston 29 provided in the lower end of valve stem 26 and cylinder portion 30 formed in the lower end of the valve stem casing 24. 54 is a cylindrical member supported by the valve stem 26 and slidable against the inner duct 19 and the upper end of it is provided a liquid port 55. This cylindrical member controls liquid turbulence of incoming and outgoing under side of the valve body as like shown in Fig. 2.

In Fig. 10 and 11, for the incoming liquid path from the inner duct 19 to the liquid chamber 15 and for the outgoing liquid path from the liquid chamber 1 5 to the liquid outgoing path formed between the inner duct 19 and outer coupling 16, respective valve systems are provided. In Fig.10, the valve system is consisted of an annular main valve body 56 and an auxiliary valve head 57 that seats on the annular valve body 56. The main valve body 56 is supported by a guide cylinder 58 and the lower portion of the guide cylinder 58 is slidably held with the guide portion 59 mounted to the top end of the inner duct 19. With the step portion 60 of this guide portion 59 and step portion 61 at the lower end of the guide cylinder 58, a dash pot 62 is formed.The guide portion 59 is provided with a plurality of ports 63 for flowing liquid in the inner duct 19 into the guide cylinder 58 and holds a spring 64 for always urging the guide cylinder 58 upward. The top end of the spring 64 abuts against a plurality of arms 65 provided on the inner wall of the guide cylinder 58 and the arms 65 support the valve stem casing 67 which further holds the valve stem 66.

To this valve stem 66 of auxiliary valve head 57, a piston 68 is provided. Also to the lower end of the valve stem casing 67, a cylinder portion 69 is provided. With these, the dash pot 70 is formed.

71 is a spring to push the auxiliary valve 57 upward. 72, a fixed housing cylinder to hold sliding of the guide cylinder 58. As the lower end of this housing cylinder 72 abuts to the flanged portion 73 of guide cylinder 58, the position of upper limitation of the cylinder 58 is governed.

74, a port provided at the lower end of the guide cylinder 58. When the valve body 56 comes to seat on the seat 28 at the top end of the outer coupling 16, the path in the duct 19 and path formed between the inner duct 19 and outer coupling 16 come to communicate, as the lower end of the fixed cylinder 72 is departed from the flanged portion 73 of the guide cylinder 58.

An example shown in Fig. 11 is as that instead of the auxiliary valve head 57 being placed to the guide cylinder 58 as in Fig. 10, it is attached to the supporter 75 of the bottom of the bladder 5.

Also the top end of the spring 64 is abutted to a stopper 76. Same parts having same numerals in Fig. 10 and 11 as those in Fig. 1-9 perform same functions.

Fig. 12 shows a different type of embodiment than said embodiments. In this Figure, the upper portion of the inner duct 19 forms a guide cylinder 77 extending into the liquid chamber 15. In the circumferential face of the guide cylinder 77, longitudinal apertures 78 are bored. Also an annular valve body 79 is provided in the bottom of the bladder 5 into the gap portion of which the guide cylinder 77 is inserted. With engagement of the guide cylinder 77 in to this gap portion 80, a dash pot 81 is formed. Same parts having same numerals in Fig. 12 as those in Fig.1~11 perform same functions.

Fig. 13 shows an example in which the valve body 25 is mounted to the bottom of the bladder 5 with the guide cylinder 82 slidable into the inner duct 19. The dash pot 31 is formed by the flanged portion 83 at the top end of the inner duct 19 and the flanged portion 84 of the guide cylinder 82. The guide cylinder 82 is slidably engaged in the inner duct 19 and urged upward with a spring 27. The top end of the guide cylinder 82 abuts against the valve body 25 and in its upper circumferential face, apertures 39 are bored. In Fig.13, same parts having same numerals, though not explained, as those parts in Fig.1~12 perform same functions.

In the embodiments shown in Fig.1~13, liquid flows from the inlet port 32 through the inner duct 19 into the liquid chamber 15 and with air spring action of the bladder 5, pulse is absorbed. Then through the outlet path 49 between the inner duct 19 and outer coupling 16, liquid flows out of the outlet port 33 to respective hydraulic devices. In this instance, if an abrupt variation of pressure or force is imparted to the valve 25 as the pump starts operation or the like, by virtue of dash pot 31, speed of such pressure is downed and the valve body 25 is slowly moved.

Fig.14 shows graphs representing results of high frequency pulsation absorption by use of pressure dampening means of the conventional embodiment and those of the present invention.

In (a), pulsation of pressure liquid through hydraulic unit is oscillographically recorded in which general pressure variation shows 15 kg/cm2. (b) shows the case where a conventional accumulator is associated to the above piping. In this instance, the upper graph records the inlet side of accumulator which amounts 6.2 kg/cm2.

Ths proves that pulsation absorption has been made insufficiently. (c) shows the case where the pulse absorption means for high pressure liquid of the present invention is associated with the above piping. From the upper graph it is seen that the pressure in the inlet side is 6.2 kg/cm2 while the outlet side represented by the lower graph is only 1.0 kg/cm2. This proves that how effectively the absorption has been performed.

It is to be noted the present invention is not limited to the above embodiments, any modification may be made without departing from the spirit of the present invention. For example, the case where the inner duct 19 is connected to the inlet port 32, this may be connected to the outlet port side. Also the lower portion of the inner duct 19 is turned at 90 degrees as an elbow, but this inner duct without bend may be connected by providing an inlet port in the bottom of the outer coupling.

Claims

1. Pulse absorption device for high pressure liquid comprising a pressure vessel housing a gas bladder therein, dual valve cylinders consisting of inner and outer cylinders located under the vessel, pulse of high pressure delivered from one of the valve cylinders to the pressure vessel is absorbed with contraction action of said bladder, the high pressure liquid is flown out through the other valve cylinder, said liquid supplying piping and flowing out piping are connected to the end of said dual cylinders respectively and by virtue of provision of a dash port, opening and closing of the inner end of cylinders with valve are made slowed as pulse is further absorbed in throttled liquid stream passing by asid daeh pot.

2. In pulse absorption ds#ce for high pressure liquid as claimed in Claim 1, said liquid supplying piping and liquid flowing out piping are connected at the outer end of the dual cylinders in the same piane respectively.

3. In pulse absorption device for high pressure liquid as claimed in Claim 1, towards the inside face of the vessel housing a bladder, an inlet port and outlet port of annular shape are provided.

4. In pulse seorption device or -igh pressure liquid which comprises a psssuro vessel, a bladder to b3 Tiled with pressure gas and housed in the vessel, dual cylinders p vldGd to the bottom & ha vessel, which dual cylinders consisted of inner and outer cylindes Xr incoming and outgoing liquid rasps tively. Valve means positioned above said dual cylinders for opening and closing fluid paths communicated to the liquid chamber in the pressure vessel charnctenzed in that:: said dual cylinders are consisted of inner and outer cylinders concentrically positioned, the inner cylinder is for incoming liquid and a path formed between the inner and outer cylinder is for outgoing liquid, said valve means includes a valve seet formed at the periphery of the bottom opening of tho pressure vessel and opening of said outer cylinder and valve body for closing said seat, means for supporting and guiding the up-down movement of said valve body which means is provided with a dash pot for slowing the abrupt movement of the valve body caused by sudden pressure variation.

5. Pulse absorption device for high pressure liquid as claimed in Claim 4 in which means for supporting and guiding includes a valve stem connected to the valve body, a valve stem casing attached in the inner duct, a spring to urge the valve body upward, a piston attached to the lower end of the valve stem and a cylinder formed at the lower end of the valve stem casing and with engagement of the piston to the cylinder, a dash pot is formed.

6. Pulse absorption device for high pressure liquid as claimed in Claim 4 characterized in that means for supporting and guiding the valve body has a guide member consisted of an inside sliding cylinder sliding with the inner cylinder, an outside sliding cylinder sliding with the outer cylinder and means for connecting the inner cylinder and outer sliding cylinders and a spring for pushing said guide member upward and a dash pot is formed by engagement of the step portion of the upper end of said inside cylinder with the step portion of said inner sliding cylinder, further, at the upper end periphery of said inner sliding cylinder, a plurality of apertures are bored.

7. Pulse absorption device for high pressure liquid as claimed in Claim 4 characterized in that means for supporting and guiding the valve body has a guide member consisting of an inside sliding cylinder sliding with the inner cylinder, an outside sliding cylinder sliding with the outer cylinder and means for connecting the inner sliding cylinder and outer cylinder and a spring for pushing said guide member upward and a dush port is formed with a step portion of upper step portion of said inner sliding cylinder and a step portion of said inner sliding cylinder and further, in the upper periphery of the inner sliding cylinder, apertures are bored.

9. In pulse absorption device for high pressure liquid which comprises a pressure vessel, a bladder housed in the pressure essel, dual cylinders provided to the bottom of the vessel, which dual cylinders consisted of inner and outer cylinders for incoming and outgoing liquid respectively, valve means positioned above said dual cylinders for opening and closing fluid paths communicated to the liquid chamber in the pressure vessel:: said dual cylinders are consisted of inner and outer cylinders concentrically positioned, the inner cylinder is a path for incoming liquid and a path formed between the inner and outer cylinder is for outgoing liquid, said valve means includes a main valve body for opening and closing the path formed by said inner and outer cylinders and an auxiliary valve body for opening and closing the inner cylinder and guide means for guiding the uptown movement of respective valve body and said guiding means is provided a dash pot for slowing abrupt movement of respective valve body.

9. In pulse absorption device for high pressure liquid as claimed in Claim 8, means for guiding respective valve body includes a guide cylinder supporting the main valve body and slidable against the inner cylinder and a valve stem supporting the auxiliary valve body, said valve stem is supported with a valve stem casing which in turn, supported with arms in the guide cylinder which altogether is allowed to make up and down movement.

10. In pulse absorption device for high pressure liquid as claimed in Claim 8, means for guiding and supporting respective valve body includes a guide cylinder supporting the main valve body and to be slidable with the inner duct and an supporter attached to the bottom of the bladder for supporting the auxiliary valve body.

11. In pulse absorption device for high pressure liquid which comprises a pressure vessel, a bladder housed in the pressure vessel, dual cylinders provided to the bottom of the vessel, which dual cylinders consisted of inner and outer cylinders for incoming and outgoing liquid respectively and valve means attached to the bottom of the bladder;; said dual cylinders are consisted of an inner and outer cylinder concentrically positioned and the inner cylinder is a path for incoming liquid and a path for outgoing liquid is an annular space between said inner cylinder and outer cylinder, the upper portion of said inner cylinder extends into the liquid chamber, and its periphery is provided longitudinal apertures, said valve means includes a valve body to close the seat formed at the top opening of outer cylinder, and valve body is provided at the bottom of bladder, said valve body has a recessed gap portion into which the upper portion of said inner cylinder engages to form a clash pot.

12. In pulse absorption device for high pressure liquid which comprises a pressure vessel, a bladder housed in the pressure vessel, dual cylinders provided to the bottom of the pressure vessel, which dual cylinders consisted of inner and outer cylinders, one for a path for incoming liquid and the other for a path for outgoing liquid and valve means attached to the bottom of the bladder; said dual cylinders are consisted of inner and outer cylinders of substantially same concentric shape, the inner cylinder is for a path for incoming liquid and a path formed between the inner cylinder and outermost cylinder is for outgoing liquid, and on the upper end of said inner cylinder, a guide cylinder which is always urged upward is jointed and the periphery of said guide cylinder is provided a plurality of apertures; a dash pot is formed by engagement of a flanged portion formed at the lower end of said guide cylinder with a flanged portion formed at the top end of the inner cylinder whereby the valve body supported by the bladder and abutted by the top end of said guide cylinder is protected from being subjected to abrupt force caused by pulsation from associated piping.