DE1650341A1 - Pressure-relieved branch valve - Google Patents

Description

C lark E qu i ρ m e nt Comp a η y in Buchanan, Michigan (USA)

Pressure relieved branch valve.

The invention relates to a pressure * Relieved branch valve with a valve housing in which a chamber, an inlet, an outlet and an overpressure outlet for the pressure medium going into the chamber open, as well as two slidable valve slides in the chamber are provided.

When transporting and handling goods, it is generally customary to use hydraulically operated piston / cylinder arrangements for lifting and lowering loads of different weights, when the goods are handled between the individual storage locations or are fed from a storage location for further processing. For example, hydraulic cylinders are consistently used to raise and lower the lifting fork on forklift trucks. It is based on the USA patent no. 3,213,967 of the applicant dated October 26, 1965. It. It is desirable to equip such forklifts with quick lift systems in order to achieve the highest possible speed under certain load conditions. Many of the known hydraulic systems for lifting and lowering lifting forks on forklifts have conventional hydraulic pumps with constant displacement together with non-regulating Richturigselventtlen. These known systems have a number of disadvantages, one of which is that after the selection of a pump capacity suitable for the highest lifting speed in the unloaded state, the lifting speed under load is too great.

Accordingly, it is a main goal of the

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IAD ORIGINAL

finding a flow control valve to create the one novel arrangement for branching off pressure medium from an inlet into a positive pressure outlet when the The pressure in the pressure medium outlet has a predetermined value . enough* .

The invention aims to create a Flow control valve, which in particular together with a standard hydraulic pump with constant Sehluekvolume is used and serves * a Pressure medium flow from the pump into the overpressure outlet • to be diverted when the pressure medium pressure in the outlet of the φ valve reaches a predetermined value. ■

Furthermore, a pressure-compensated branch valve is to be created that can easily be used with a conventional constant displacement pump and a piston / cylinder arrangement cooperatively arranged in this way it can be that the valve allows the highest possible extension speed without load, while it is at Achieving predetermined load conditions derives a partial flow of pressure medium from the cylinder / piston arrangement, thereby reducing the extension speed of the piston to reduce.

Another object of the invention is

ml to provide a druckausgegliehenen diverter valve having a first and a second valve slide ^ _s wherein the second valve spool is arranged such that it inhibits the movement of the first Ventilsehiebers, until a certain outlet pressure reached, whereupon the first valve slide are brought into a position can, in which he branches off a pressure medium flow from the inlet to the overpressure outlet.

Another object of the invention is in the creation of a diverter valve as described above in which the first valve spool means to achieve a pressure difference on the? comprises first valve slide which is used to generate a movement

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of the first valve slide is used in a position in which a partial flow of pressure medium is branched off from the inlet if, the pressure in the outlet reaches a predetermined value.

Another object of the invention is finally in the creation of a pressure-balanced branch valve that is extremely efficient and which can easily be used in conjunction with a known constant displacement pump, the properties of a hydraulic pump with variable displacement at a much lower cost to achieve.

In a preferred embodiment of a branch valve for flow control according to the invention a housing is provided with a cylindrical chamber therein having an inlet, an outlet and a positive pressure outlet communicating with the cylindrical chamber. In the cylindrical chamber, a first and a second valve slide is slidably arranged, the first Valve slide has flow passages which allow a pressure medium flow between inlet and outlet, as well as control grooves and openings that allow controllable fluid transfer from the inlet to the overpressure outlet allow. The second valve slide is arranged to move the first valve slide into a closed position Bring seeks in which the flow between the inlet and the overpressure outlet is interrupted while he is at a predetermined outlet pressure executes a movement that allows the first valve slide, a partial flow of pressure medium branch from the inlet to the overpressure outlet .. Furthermore, one is caused by the movement of the second valve slide unaffected spring arrangement is provided which presses the first valve slide into the position in which the pressure medium transfer into the overpressure outlet is blocked, the spring force being controlled by a predetermined Pressure drop across the flow passages is overcome. The present invention thus sets

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Flow control valve represents a first pressure medium flow brings about until the pressure in the pressure medium outlet of the valve reaches a predetermined value, whereupon the Valve then part of the pressure medium entering it can flow through an overpressure outlet.

Further objects and advantages of the invention and its structure and mode of operation are evident from the following description in connection with the accompanying drawing.

The drawing shows an embodiment of the invention.

Fig. 1 is a vertical section through the Longitudinal axis of the branch valve according to the invention.

Fig. 2 is a schematic representation of an application of the branch valve according to the invention.

In Fig. 1, a flow control valve or branch valve according to the invention is designated as a whole by 10. In the illustrated embodiment, it comprises a housing 11 with a cylindrical chamber 12 in it. The cylindrical chamber 12 is connected to a pressure medium inlet 14 in the housing 11. That Housing 11 has an internal thread at 16 into which Usual connectors for connecting the branch valve to a hydraulic circuit are screwed. The case 11 comprises an opening 18 provided with a thread on the side of the chamber 12 facing away from the inlet 14. The threaded opening 18 is coaxial with the chamber 12 and receives a threaded plug 20, to close the end of the chamber in question. It it is clear that the one on the threaded opening located side of the housing can also be closed by a wall part integral with it, whereby the threaded plug 20 can be omitted. The providence of However, threaded plug 20 facilitates manufacture of the present valve and comes with easy assembly the valve parts in the chamber 12 benefit.

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The housing 11 has a pressure medium outlet 22 with an internal thread 24, into which a conventional connecting piece is screwed in a manner similar to that of the inlet 14 provided with an internal thread. The pressure medium outlet is connected to an annular recess 26 in the inner wall of the chamber 12 for the passage of the flow. The housing 11 also includes an overpressure outlet 28 with an internal thread 30 _s . Usual connector for. Connection of the tfeeröruekauslass with. the pressure medium tank. 82. "(Pig · 2) connects _β The overpressure from XaS 28 is connected to an annular recess 32 for the pressure medium to pass into the inner wall of the sylin« "■ ™ third chamber 12. The annular transfer chambers 2 $ and 32 are arranged at a distance from the inlet along the axis of the cylindrical chamber 12.

In the chamber 12 there is a first valve slide in the form of a slide sleeve 34 'Er: has a cylindrical outer surface 36 which has a diameter essentially the same as that of the cylindrical chamber 12, so that the slide sleeve 34 can slide along the axis of the cylindrical chamber . The slide sleeve 34 contains a cylindrical recess 38 on the inside, which is open at one end and is in constant communication with the pressure medium inlet 14

Slide sleeve 3 ^ has a bottom 40 with a number of flow passages 42 which allow a throttled pressure medium flow and thus produce a pressure medium connection between the inlet 14 and the outlet opening 22, as will be explained in detail below. A pressure medium flow through the flow passages 42 in the slide sleeve Jk is somewhat throttled and thus a pressure drop is brought about at the passages, which results in a pressure difference that loads on the effective surfaces of the opposite sides of the base 4o and acts against the compression spring 72, as shown in FIG .Details is shown. _:

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The slide sleeve 34 also comprises a number of radially arranged openings 44, which produce a pressure medium flow between the inlet 14 and the relief discharge line 28 when the slide sleeve 34 is brought into a preselectable position in the chamber 12 * as will be described below The outer surface 36 of the slide sleeve 34 contains several control grooves or recesses 46, each of which is attached in the vicinity of an opening 44. The.-Controlled recesses 46 are, _wesentlichen, of V-shaped cross-section, wherein each recess is a continuous volume in the abnehmend® @ - has --zugehörigen of Qms opening 44 leading away Rioatüiig. One in the usual way as feathers · »ο ©! ⁵ # 8 ring formed stop is in an appropriate ■ - r ia hat ä © inner surface of the cylindrical chamber 12 / attached. ""It is at an axial distance from the annular liquid transfer 52, so that when the slide sleeve 3 ^" rests against the resilient ring 48, it blocks the liquid transfer from the inlet to the overpressure outlet 28,. . ". ■■■

A second valve spool 50 has an outer diameter that is substantially identical to that of the Zylihdrischen chamber 12 matches and is in this mounted displaceably and coaxially with the first valve slide 34. The second valve spool 50 contains a substantially cylindrical inner cavity 52 which is enclosed by the cylindrical outer wall 5 ^ is «This has an end face 56 that the outer surface of the bottom 40 of the slide sleeve 34 is present. In the tubular outer wall 54 is a Number of elongated openings 58 are provided, which are extend to the end face 56. The elongated openings 58 create a constant pressure medium connection between the inlet 14 and the outlet 22 via the flow through » leave 42 in the bottom 40 of the slide valve 34. The second Valve spool 50 includes an axially extending Bore 60 through which the shaft 62 can be slid

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Peder pressure piece 64 reaches through. An outer shoulder 65 of the second valve slide 50 with a reduced diameter, together with a shoulder thereof, forms a holder for one end of a spiral * compression spring 68, which is arranged between the shoulder 66 and the inside of the plug 20. The spiral compression spring 68 presses the end face 56 of the second valve slide 50 against the bottom 40 of the slide sleeve 34 and so this against the stop ring 48.

The spring pressure piece 64 has a collar 70 of enlarged diameter, which forms the seat for a spiral compression spring 72 which is arranged between the collar 70 of the peder pressure piece and the outside of the bottom 40 of the slide sleeve J54. The Λ

outer end of the shaft part .62 of the peder pressure piece rests against the adjacent end of the plug 20 and holds the collar in a fixed position within the chamber 12, the spiral compression spring 72 serves as an additional means, around the valve spindle 34 against the stop ring 48 press, the force exerted by the spring 72 independent of the position of the second valve slide 50 is.

Preferably is in the peripheral surfaces of the first and second valve spool ^ 4 and 50, respectively Number of annular grooves 74 provided. The grooves 74 support the maintenance of the hydraulic equilibrium at the valve spools and reduce the leakage Losses between the peripheral surfaces of the valve spool and the cylindrical chamber 12. In the housing 11 is a Channel 76 is provided, the any liquid that has passed behind the second valve slide 50, in the upper pressure outlet 28 leads back.

It is now the mode of action based on Fig. 1 and 2 described. For example, suppose that the housing 11 of the branch valve by conventional fittings that are in the inlet 14, in the Outlet 22 and the overpressure outlet 28 screwed in

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is connected to suitable pressure medium lines. Let the outlet be connected to the variable volume chamber 78 of the cylinder / piston arrangement. The inlet 14 is connected to a hydraulic pump 80 with a constant displacement. The overpressure outlet 28 is finally connected to a conventional pressure medium container 82. In such an arrangement, a pressure medium flow must take place from the inlet 14 through the outlet 22 to the outside into the pressure chamber 78 so that the piston 81 can extend. Correspondingly, the pressure in the outlet 22 depends on the load P on the outer end of the piston 8l. The pressure medium volume required to extend the piston by a predetermined distance is independent of the load on the piston, assuming a non-compressible pressure medium. The present branch valve represents an arrangement which branches off pressure medium from the inlet through the overpressure outlet 28 at a predetermined outlet pressure. In this way, the volume of pressure medium supplied to the chamber 78 of the cylinder / piston arrangement through the outlet 22 is reduced and the extension speed of the piston 81 is slowed down. The compression spring 68 is dimensioned so that the second valve slide 50 moves outward from the bottom 40 of the slide sleeve ~ $ k when the pressure in the outlet reaches a certain value, this value being determined by the load P on the piston 81 at which the extension speed is to be reduced. The compression spring 72 is designed so that after the second valve slide 50 has moved away from the slide sleeve ^ 4, the pressure difference resulting from the pressure drop at the flow passages 42 affects the effective area of the base 40 and the spring begins to compress so that the Control grooves 46 can come in connection with the annular liquid passage 32. From this moment on, a partial flow of pressure medium from the inlet into the overpressure outlet

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branched off to that of the chamber 78 of the cylinder / piston assembly 79 to reduce the volume of pressurized media supplied.

When the load on the piston 81 of the cylinder / piston assembly 78 is light and the piston is to be extended quickly, the parts of the branch valve are as shown in FIG The bottom 4o of the slide sleeve 34 is pressed so that the slide sleeve j54 is forced into a first position against the stop ring 48, in which it completely blocks the flow of pressure medium between the inlet 14 and the overpressure outlet 28. In this stage, the entire flow of pressure medium passes from the inlet via the Flow passages 42 in the bottom 40 of the slide sleeve 34 via the elongated openings 58 into the valve slide 50 and via the outlet 22 into the cylinder / piston arrangement 79. During this time, the second spiral compression spring 72 also presses the slide sleeve J> K resiliently against the stop ring If the load on the piston of the cylinder / piston arrangement increases to the value at which the extension speed of the Ko If, however, it is to be significantly reduced, the pressure medium pressure in the outlet 22 and thus the pressure in the recess 52 of the second valve slide 50 will cause the latter to move away from the slide sleeve, compressing the spiral compression spring 68. The slide sleeve ^ 4 is then only pressed against the stop ring 48 by the spiral compression spring 72. The pressure drop at the flow passages 42 creates a pressure difference that acts against the compression coil spring 72. The coil compression spring 72, which is also designed so that it begins to be compressed when the pressure difference at the fluid flow passages 42 reaches a predetermined value, is thus compressed by the slide sleeve 24 when this predetermined value of the pressure drop is reached, whereupon the slide sleeve © see in Flg. 1 to the left

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will move. Then the control grooves 46 cut the Allow annular fluid transfer J2 and the passage of pressure medium from the inlet 14 via the radially arranged passages 44 and the control grooves 46 to the outside through the overpressure outlet 28.

The present branch valve can thus be used to bring about a first pressure medium flow in a first load condition, for example under low load, serve while the pressure medium outlet flow lowers under heavy load. In this way many properties of a hydraulic Pump with variable displacement achieved at significantly lower cost.

The invention has been described above in conjunction with a cylinder / piston arrangement. Obviously, however, the invention is equally suitable for use in any pressure medium system, in which the diversion of a partial flow of pressure medium is sought as a function of the outlet pressure.

BATH ORIGINAL

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Claims (10)

Claims. 1. Pressure-relieved branch valve with a valve housing in which a chamber, an inlet, an outlet and an overpressure outlet for the pressure medium, all of them open into the chamber, and two valve slides which can be displaced in the chamber are provided, characterized in that that the first valve slide between a first position in which it the pressure medium flow between the inlet (14) and the overpressure outlet (28) blocks, and a second position is movable in which the inlet (1 "4) with the overpressure outlet (28) connection that the second valve slide from a position in which it (| pushes the first valve slide into its first position, can be moved into a second position in which it controls the movement of the first valve slide into its second position allows, and that the second valve slide is in communication with the outlet (22) and look into the second Moved position when the liquid pressure in the outlet (22) reaches a predetermined value, so that the first valve, slide then move into its second position and a connection between inlet (l4) and overpressure outlet (28) can produce. 2. Branch valve according to claim 1, characterized in that the second valve slide is resilient is pressed against the first valve slide when the "™ Liquid pressure in the outlet (22) below the predetermined one Value lies. J5 »branch valve according to claim 2, characterized characterized in that the second valve slide by a spring (68) supported at the end of the chamber (12) against the first valve slide is pressed. 4. Branch valve according to one of claims 1 to 3 * characterized in that a device is provided, which holds the first valve slide in its first position when the fluid pressure in the off 009837/0488 let (22) the predetermined value at which the second Valve slide moved into its second position, has achieved a movement of the first valve slide in the direction to its second position, however, only when the predetermined value of the pressure medium pressure in the outlet (22) is exceeded. 5 · Branch valve according to claim 4, characterized in that the device is a spring (72) includes, on the one hand against the first valve spool and on the other hand against a with a shaft (62) the second slide penetrating and at the end of the chamber (12) supported pressure piece (62,70,64) rests. 6. Branch valve according to one of claims 1 to 5, characterized in that the first valve slide as a slide sleeve (34) which is open towards the inlet (l4) and has a bottom (4o) at the other end is formed with an outer shape adapted to the cross section of the chamber (12) of the valve housing (11) and can slide axially in the chamber that the slide sleeve (34) has a cavity (38) inside, which with the Outlet (22) is in communication, and that the slide sleeve (34) contains control grooves (44,46) which have a pressure medium connection between the inlet (14) and the overpressure outlet (28) when the slide sleeve (34) is moved to its second position. -7. Branch valve according to Claim 6, characterized in that the slide sleeve (34) is a device to achieve a pressure drop between inlet (14) and outlet (22) during the flow of the pressure medium through the valve (1.0). 8. Branch valve according to claim 7 * thereby characterized in that the means to achieve a Pressure drop at least one throttling flow passage (42) provided in the base (40) of the slide sleeve (34) includes. 0098 37/0488 9 # Branch valve according to one of the claims 1 to 8, characterized in that the chamber (12) of the valve housing (11) is designed as a continuous bore is and both valve spools are coaxially arranged one behind the other therein. 10. Branch valve according to one of claims 1 to 9 *, characterized in that in the circumference f of the slide sleeve (34) and the first valve slide (50) annular grooves (74) to prevent the pressure medium transfer between the peripheral surfaces and the inner wall of the chamber (12 ) are provided, .11. Branch valve according to one of Claims 1 to 10, characterized in that a stop (48) to limit the movement of the first valve slide (34) is provided in the direction of the inlet (14). 009837/0488 Blank page