EP0893607A1 - Solenoid-actuated outlet valve - Google Patents

Abstract

A seat closure component (13) is provided for a main valve seat (17), which is activated in the closure direction by a variable difference between the outlet pressure and a control pressure derived form the load pressure. A pre-control valve (V), operable by the magnets (M), is provided for the control pressure. The main valve (H), formed by the main valve seat and the seat closure component, has a pressure balance (W) with seat valve sealing function (S), which with the main valve forms a load pressure independent two-way flow regulator (Z), which under load pressure and in the closed position of the main valve is sealed in a leakage-free manner.

Description

The invention relates to a solenoid operated drain valve according to the preamble of Claim 1.

Magnetic poppet valves are from data sheet D 7490/1 from Heilmeier & Weinlein, March 1996 (Types EM 11 to 31) are known, which are leak-free in the closed position. These drain valves are inexpensive and reliable, but as pure Black / white valves unable to control a clear ramp function i.e. regulate the flow rate depending on the stroke and pressure. Especially in Lift modules for forklift trucks require a ramp function when in use of these known drain valves, for example electronically, with considerable Effort is brought about to the need for an expensive and elaborate To bypass two-way current regulator, which would also not be leak-tight.

In order to achieve a ramp function hydraulically for this type of seat valve, it is known from DE-U-29 61 7922, which is between the pilot valve and to design the spring provided for the magnet as a hard spring with a steep characteristic, a stroke-dependent quantity setting device between the seat closing element and the main valve seat to provide, and to modify the pilot valve. Indeed the ramp function is not independent of the load pressure.

From DE-A-42 39 321 it is known to have a drain valve in a lifting module for lift trucks to be designed as a two-way current controller to provide a ramp function independent of the load pressure to be able to control. This is with a high expenditure on hydraulic components connected, as it is not acceptable for simple forklift trucks in the market, and with the disadvantage that the lifting module is only "forklift-tight" in the closed position, i.e. Leakage oil flows out to a small, but nevertheless undesirable extent.

In a drain control valve known from EP-A-0 291 140 is in the main valve no pressure compensator provided, but a differential pressure generator arranged downstream, the spring-loaded is pushable in a bell-shaped cavity to reduce the current to make. In a hydraulic system known from EP-A-0 279 315 Control device, e.g. for a lifting cylinder, a two-way flow controller is one Pressure compensator with a poppet valve function assigned in the shut-off position Control pressure keeps leakage free. A main seat valve is not provided, but one adjustable orifice plate, which should keep the load pressure. Since it is difficult to use the orifice plate to use for load holding is a in most embodiments Black / white switching valve designed to hold the load pressure.

In a control device for the volume flow known from EP-A-0 548 513 no pressure compensator assigned to the main valve, so that there is no load pressure independence given is. The closing movement of the main valve is via a throttle combination subdued.

Further prior art is contained in DE-A-35 37 760 and EP-A-0 041 247.

The invention has for its object a structurally simple, small-sized magnet-actuated To improve the drain valve of the construction 50 known from DE-U-29 61 7922, that the ramp function is independent of the load pressure.

The object is achieved according to the invention with the features of claim 1.

The structurally simple combination of the black / white drain valve with the pressure compensator leads to load pressure independence, making a real two-way flow regulator is created, which is small and inexpensive. The one provided in the pressure compensator Seat valve function in combination with the seat valve function in the main valve and in Pilot valve ensure that the drain valve is leak-tight in the closed position. Because the load pressure is shut off in the main valve and in the pilot valve without leakage oil, and additionally also in that which is then rendered inoperative by means of the poppet valve function Pressure compensator. The seat valve function is eliminated in the regulating play of the pressure compensator. In The lowering valve of a lift truck has the advantage that the ramp function is load-dependent to control, either with a proportional magnet or even with a conventional one, in its characteristic to the hard spring characteristic customized magnets. Even when there is a long break in operation, the Load or a component of the forklift under load is held. It will so to speak, the trick made according to DE-U-29 61 7922, a black and white drain valve by using a hard spring and a special design of the main seat valve to a ramp function, added profitably through the pressure compensator to the ramp function or quantity control can be controlled independently of the load pressure and in the pressure compensator in the closed position Prevent leakage through the poppet valve function. This can be done with little construction Doing effort and simple components leads to small size a drain valve, which is particularly useful for simple forklifts.

The pressure compensator is expediently downstream of the main valve seat arranged.

According to claim 3, only one is the black / white valve concept for the pressure compensator only minimally influencing modification required. The downstream of the main valve set pressure is tapped on one side of the pressure compensator while the load pressure is brought to the other side of the pressure compensator, on which the poppet valve function is provided for oil-free shut-off. The drain valve can be in the accommodate the same installation space as a conventional black / white drain valve.

The diaphragm piston as a slide part is simple in terms of production technology designed with an integrated cone sealing surface.

According to claim 5, the orifice piston works with its control end except for one Throttle opening or a control notch slide-tight together with the outflow opening. The throttle opening or the control notch ensures, among other things, the correct Close the main valve and can also be used for volume control become.

According to claim 6, the two-sided loading surfaces of the diaphragm piston same size.

According to claim 7 is a positive overlap in the shut-off position of the piston available, which only needs to be slide-tight.

The piston is structurally simple in direct extension of the Main valve seat arranged.

According to claim 9, the sleeve provided for the main valve seat anyway extended to the bore for the piston and the valve seat for the additional To accommodate the sealing function. The connecting channel that brings the load pressure to the pressure compensator can be provided in the sleeve. But it is also conceivable that Lead the load pressure to the pressure compensator in a different way.

According to claim 10, the sleeve contains the main valve seat and the throttle, via which the pilot valve the opening and closing movements of the main valve controls. This throttle is expediently smaller than or at most as large as the passage of the pilot valve, the passage of the pilot valve expediently at most the size of a bore with a diameter of 0.6 mm.

According to claims 11 and 12, the spring of the piston of the pressure compensator can alternatively outside the piston or be housed inside the piston, in the latter case to reduce the size.

According to claim 13, the pilot valve is also leak-tight (seat valve), the spring is a hard spring with a steep characteristic curve, with the appropriate tuning of the magnet to control the ramp function.

It is also expedient according to claim 14, the main valve with a quantity setting device provided that the black / white valve similar to a control valve be let that works with the pressure compensator independent of the load pressure.

As is customary with such drain valves in black and white construction, is according to claims 15 or 16 selected an interconnection in which the main valve solenoid is closed or open. In the closed position of the main valve leak-free tightness is guaranteed.

Fig. 1

einen Längsschnitt durch ein Ablaßventil, das bei stromlosem Magneten leckagefrei dicht absperrt,

Fig. 2

eine andere Ausführungsform eines Ablaßventils, das bei stromlosem Magneten leckagefrei absperrt,

Fig. 3

eine weitere Ausführungsform eines Ablaßventils in einem Langsschnitt, wobei das Ablaßventil bei stromlosem Magneten frei durchgängig und in der Schließstellung leckagefrei dicht ist,

Fig. 4 + 5

schematische Blockschaltbild-Darstellungen der Ausführungsformen des Ablaßventils der Fig. 1 und 3, und

Fig. 6

ein Diagramm (Stromstärke bzw. Druck über der Menge) zum Ansprechverhalten des Ablaßventils.

Embodiments of the subject matter of the invention are explained with the aid of the drawing. Show it:

Fig. 1

a longitudinal section through a drain valve which seals tightly without leakage when the magnet is de-energized,

Fig. 2

another embodiment of a drain valve that shuts off leak-free when the magnet is de-energized,

Fig. 3

a further embodiment of a drain valve in a longitudinal section, the drain valve being freely continuous when the magnet is de-energized and leak-tight in the closed position,

Fig. 4 + 5

schematic block diagram representations of the embodiments of the drain valve of FIGS. 1 and 3, and

Fig. 6

a diagram (current or pressure over the amount) of the response of the drain valve.

A drain valve A in Fig. 1 is designed as a two-way flow controller Z and has between a line 2, the pressure to be controlled P or a quantity to be regulated leads, and a leading to a tank T drain line 3 designed as a seat valve Main valve H open. In a housing 4 designed as a screw-in insert a magnet M, suitably proportional magnet or one in its characteristic Modified simple switching magnet for a pilot valve arranged in the main valve H. V arranged with which the main valve H is actuated. Furthermore, A pressure compensator W is expediently provided downstream of the main valve H.

In the magnet M are a stationary part 6 and one when current is applied Magnetic coil 8 upward adjustable magnet armature 7 included. One supported on part 6 hard spring 9 with a steep characteristic curve acts on a tappet 10, the for example, the conical end forms a closing member 11 for the pilot valve V and with a valve seat of a passage 14 in a seat closing element 13 of the Main valve H works together. The pilot valve V is a seat valve, which in its The closed position is leak-tight. The pilot valve V monitors the connection between a control chamber 12 and the discharge line 3. Between the control chamber 12 and the line 2 is one Throttle D provided. The seat closing element 13 of the main valve H has one conical or spherical sealing surface 15, which cooperates with a main valve seat 17, arranged like the throttle D in a sleeve 5 inserted into the line 3 is. The sleeve 5 is screwed to the housing 4.

The area of action of the seat closing element 13 in the control chamber 12 is larger than the cross section of the main valve seat 17 of the main valve H. downstream of the Main valve seat 17, a bore section 18 is provided, which has an annular flange 16 of the seat closing element 13 forms a quantity setting device. The The ring flange 16 is connected to the sealing surface 15 of the seat closing element 13 provided such that when the main valve H is closed, the annular flange 16 in the Bore section 18 dips. The main valve H is leak-free in the closed position tight.

The bore section 18 is extended in Fig. 1 by a bore 19, of which lateral outflow openings 20 (in the form of orifices or orifices) lead to line 3. In the bore 19, a piston K is after the pressure compensator B. Kind of a slide led. This has a control end facing the main valve H. 21 and the main valve H facing away from a conical or spherical sealing surface 23rd on, which has a seat 22 in the sleeve 5 with a seat valve function (leak oil-free tight) cooperates when the piston K of the pressure compensator W in that shown in Fig. 1 Shut-off position, in which its control end 21 e.g. with a positive Cover U closes the outflow openings 20. The poppet valve function K of the pressure compensator W is indicated with S. A lower end 24 of the piston K is located in a chamber 28 which is connected to line 2 via a channel 27.

The end 24 is urged downwards by a spring 25 in FIG the spring 25 is supported in the sleeve 5. The spring 25 surrounds the piston K on the outside.

A weak closing spring 29 for the seat closing element can be located in the control chamber 12 13 may be provided. At the control end 21, a tax notch or chamfer F be provided, the predetermined, small outflow cross-section to the outflow opening 20 also leaves open in the shut-off position of the piston K.

Since the spring 9 keeps the pilot valve V closed when the magnet M is de-energized and the operating area of the seat closing element 13 in the control chamber 12 is larger than the cross-sectional area of the main valve seat 17, is when de-energized Solenoid the main valve H kept closed. Since the pilot valve V and that If the main valve H is leak-tight in its closed positions, the piston K also becomes tight the pressure compensator W held in its shut-off position and the sealing surface 23 is on Seat 22 on, so that the chamber 28 is blocked leakage-free. In the closed position (In Fig. 1 when the magnet is de-energized) the drain valve is thus leak-free tight.

If the coil 8 of the magnet M is supplied with current of a certain current strength, then the magnet armature 7 pulls the plunger 10 against the force of the spring 9 up. The pilot valve V is opened. The control pressure in the control chamber 12 changes via passage 14 in a predetermined manner. The pressure in line 2 lifts the seat closing element when the control pressure drops accordingly 13 from the main valve seat H, due to a slow response and the quantity setting device in the main valve H, the pressure P in the line 2 is not suddenly relieved, but with a predetermined ramp function. The quantity would, however, without pressure compensator W depending on the height of the pressure P vary. To achieve pressure-independent control, the Piston K of the pressure compensator pressure-compensating and orifice-like with the outflow openings 20 together, giving up its shut-off position as soon as the pressure downstream of the main valve seat has grown to a value that is in the chamber 28 prevailing pressure P minus the force of the spring 25 corresponds. thanks to the Pressure compensator W, the quantity is then regulated independently of pressure, with the control cycle of the piston K, the seat valve function S between the sealing surface 23 and the Sealing seat 22 is canceled. The pressure compensator keeps the pressure difference accordingly the current strength constant. It is useful that the spring 9 is a hard spring with a steep characteristic is that the quantity setting device is present in the main valve H. and that the passage 14 of the pilot valve is relatively small, for example not larger than a hole with a diameter of 0.6 mm. The throttle D is on the Passage cross section of the passage 14 matched so that it is maximum is the same size.

If the energization of the coil 8 is reduced, the pilot valve V increases again the control pressure in the control chamber 12 so that the main valve H the passage reduced in volume setting, the pressure compensator W still for the pressure independence worries.

If the energization of the coil 8 is completely canceled, the spring 9 closes the pilot valve V. The control pressure in the control chamber 12 presses the seat closing element 13 on the main valve seat H. The pressure P in the chamber 28 pushes the piston K in its shut-off position. The pilot valve, the main valve H and the sealing surface 23 seated on the sealing seat 22 provide the desired leakage-free Tightness ago. The pressure P is maintained.

The drain valve A is, for example, in a lifting module of a lift truck (or for a tipper) is used, in which a consumer can be pressurized with the pressure P. works against a load to this with predetermined and by energizing the Magnet M set speed to move and in the closed position hold. The drain valve A is located in the lifting module between the supply line of the consumer and the tank (see DE-A-42 39 321) and can be used for lifting and Lowering control or only used for lowering control. The drain valve is A closed when the magnet M is de-energized, it can be used, for example, for lowering control use to lower a load independently of pressure, for example was raised by controlling the pump. When lowering is used Pump the rate of lowering through the drain valve A outflowing amount controlled, in the present case independently from the prevailing pressure P.

In Fig. 2, the drain valve A has the same function as in Fig. 1 (two-way flow controller Z) modified with respect to the pressure compensator W compared to FIG. 1. And that is Piston K is a pot piston and the spring 25 is arranged inside the pot piston in such a way that they are with their lower end on the piston K and with their upper end is supported on a stop 32 which is arranged on a pin 31 which is in the Piston K can be moved. The stop 32 can be in the bore 19 on a Transition to the smaller bore section 18 in diameter in the printing direction support upwards. The piston K has e.g. a larger exposure area than the cross section of the main valve seat 17. Instead of the control notch F of Fig. 1 is in the piston K of FIG. 2 at least one throttle opening F 'to the outflow opening 20 provided. The spring space of the piston K is indicated at 30.

In Fig. 3, the drain valve A operating as a two-way flow regulator is under construction the embodiment of FIG. 1 is the same, designed so that when the magnet is de-energized M the connection between the line 2 and the outflow line 3 is open. The stationary Part 6 of the magnet M is below the armature 7 which can be moved downwards arranged. The hard spring 9 with a steep characteristic curve is supported in part 6 and below acts on the plunger 10 and thus the armature 7 upwards, so that when de-energized Magnet M opened the pilot valve V and the seat closing element 13 of the Main valve H is lifted off the main valve seat 17. The piston K of the pressure compensator is moved down from the shut-off position shown when the main valve H is open, to clear the flow path.

In a lift truck, the drain valve A of Fig. 3 can e.g. for lifting and lowering control be used. When the pump is switched on, the pressure medium flows over the open drain valve A from. With increasing current supply to the magnet M, this becomes Main valve H is closed and the pressure P and the amount for the consumer increased according to the current supply, the pressure compensator W for the Pressure independence of the quantity control ensures. With full power and closed Main valve H becomes the total available quantity to the consumer guided. If the load is to be stopped, the supply pump is switched off and the Load pressure kept leak-free. The lowering control is carried out while reducing the Current supply to the magnet M by regulating the quantity which, thanks to the pressure compensator W flows to tank T regardless of load pressure. In Fig. 3, the spring 25 of the piston K can be arranged in the interior of the piston as in FIG. 2. In addition, the piston is K without chamfer or notch.

Fig. 4 illustrates in a symbolic representation the drain valve A as a two-way flow controller in the design according to Figs. 1 and 2, i.e. without energizing the magnet M closed. The pilot valve V is not shown in FIG. 4 for the sake of simplicity shown. Thanks to the seat valve function in the main valve H and the seat valve function S the pressure compensator A in the shut-off position of the piston K, the pressure P becomes leak-free kept, although the pressure compensator W for the clean control only slide-tight needs to be.

5, the drain valve A is a two-way flow controller Z according to the embodiment 3 symbolically represented, i.e. open when de-energized. The poppet valve function In the main valve H there is also the seat valve function S of the pressure compensator P (the sealing surface 23 is then lifted off the seat 22). In contrast, is at full current of the magnet M leak-free tightness in the main valve H and in the Pressure compensator W given, since the main valve H blocks the pressure P without leakage and the seat valve function S of the pressure compensator W comes into play.

Fig. 6 illustrates in a diagram of the current I over the amount Q with the solid curve P, like the amount Q regardless of the pressure P only over the Current I is regulated, either the amount to the consumer flows or the amount that flows out of the consumer. The dashed curves P 'and P' 'indicate how the drain valve A without that directly associated with the main valve and a pressure compensator arranged downstream of the main valve, the quantity Q only could set depending on the pressure. This meant that at a certain current I the amount Q would be smaller at lower pressure P 'than the same Current I and higher pressure P '', and also that despite the same current different Speeds occurred. The solid curve P shows clearly however, that the quantity Q and thus the speed of the consumer can be controlled independently of the pressure with the current intensity I.

At its core, a leak-proof black / white valve concept with minimal Modifications and a pressure compensator with poppet valve function a full two-way flow controller formed, which is inexpensive and compact.

Claims (16)

Solenoid-operated drain valve (A) between a load pressure connection (P) and a drain connection (T), in particular for a lifting module of a forklift truck, with a seat closing element (13) assigned to a main valve seat (17), which in the closing direction is dependent on a variable difference between the discharge pressure and a control pressure derived from the load pressure can be applied, and with a pilot valve (V) for the control pressure which can be actuated by the magnet (M), characterized in that the main valve (H) formed by the main valve seat (17) and the seat closing element (13) a pressure compensator (W) with poppet valve sealing function (S) is assigned, which forms with the main valve (H) a load-independent two-way flow controller (Z) that is leak-tight under the load pressure and in the closed position of the main valve. Solenoid operated drain valve according to claim 1, characterized in that the pressure compensator (W) is arranged downstream of the main valve seat (17). Solenoid-operated drain valve according to at least one of Claims 1 or 2, characterized in that a piston (K) is provided in the pressure compensator (W) and slides in a bore (19) from an at least one lateral outflow opening (20) to the drain connection (T ) closing position can be moved until the discharge opening (20) is released and in the direction of the blocking position is acted upon by the load pressure (P), in the opposite direction by a spring (25) and a pressure downstream of the main valve seat (17) and the pilot valve (V) and that the piston (K) for securing the load pressure in the blocking position has a sealing surface (23) which can be placed on a stationary auxiliary valve seat (22). Solenoid operated drain valve according to claim 3, characterized in that the piston (K) has a slide part with a regulating end (21) and no conical sealing surface (23). Solenoid operated drain valve according to claim 4, characterized in that the piston (K) has at least one throttle opening (F ') or a control notch (F') which forms a throttled connection from the pilot valve (V) to the outflow opening (20) in the shut-off position. Solenoid operated drain valve according to claim 4, characterized in that the two-sided pressure surfaces of the piston (K) for the load pressure (P) and the pressure downstream of the main valve (H) are the same size. Solenoid operated drain valve according to claim 4, characterized in that the piston (K) covers the outflow opening (20) in the shut-off position with a positive overlap (U). Solenoid-operated drain valve according to claim 4, characterized in that the piston (K) is arranged in a direct extension of the main valve seat (17) and points with its regulating end (21) towards the main valve seat (17). Solenoid-operated drain valve according to at least one of claims 4 to 8, characterized in that the bore (19) for the piston (K) is formed in a sleeve (5) in which the outflow opening (20), one through the piston (K) limited pressure chamber (28), a connecting channel (27) from the load pressure connection (2) to the pressure chamber (28) and between the pressure chamber (28) and the bore (19) of the auxiliary valve seat (22) are arranged. Solenoid-operated drain valve according to claim 9, characterized in that in the sleeve (5) of the main valve seat (17) there is provided a throttle (D) which is operatively arranged between the load pressure connection (2) and the pilot valve (V). Solenoid operated drain valve according to claim 3, characterized in that the spring (25) of the piston (K) in the pressure chamber (28) is arranged between an abutment in the sleeve (5) and a stop on the piston (K) and the piston (K ) surrounds outside. Solenoid-operated drain valve according to claim 3, characterized in that the spring (25) of the piston (K) is arranged inside the piston (K) between a stop of the piston and an abutment (32) supported on the sleeve (5). Solenoid-operated drain valve according to claim 1, characterized in that the pilot valve (V) is a seat valve with a closing element (10) adjustable by the magnet (M) against the force of a spring (9) and a passage (14) in the seat closing element (13). and that the spring (9) is a hard spring with a steep characteristic. Solenoid-operated drain valve according to at least one of the preceding claims, characterized in that the seat closing element (13) is formed at its end which projects through the main valve seat (17) in the closed position with an annular flange (16) which is downstream with a bore section (18) the main valve seat (17) forms a stroke-dependent quantity setting device. Solenoid-operated drain valve according to at least one of the preceding claims, characterized in that the seat closing element (13) closes the main valve seat (17) under the force of the spring (9) when the magnet (M) is de-energized, and in that the piston (K) is released from the load pressure in the locked position is held. Solenoid-operated drain valve according to at least one of Claims 1 to 14, characterized in that the seat closing element (13) is lifted from the main valve seat (17) by the spring (9) when the magnet (M) is de-energized, and in that the piston (K) by the spring (25) is adjusted from the locked position.

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