EP0962661B1 - Differential pressure switching valve with electrical switch - Google Patents

Differential pressure switching valve with electrical switch Download PDF

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Publication number
EP0962661B1
EP0962661B1 EP99107503A EP99107503A EP0962661B1 EP 0962661 B1 EP0962661 B1 EP 0962661B1 EP 99107503 A EP99107503 A EP 99107503A EP 99107503 A EP99107503 A EP 99107503A EP 0962661 B1 EP0962661 B1 EP 0962661B1
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EP
European Patent Office
Prior art keywords
piston
pressure
control valve
differential
valve according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP99107503A
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German (de)
French (fr)
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EP0962661A1 (en
Inventor
Georg Neumair
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Hawe Hydraulik GmbH and Co KG
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Hawe Hydraulik GmbH and Co KG
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Publication of EP0962661A1 publication Critical patent/EP0962661A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/028—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the actuating force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B5/00—Clamps
    • B25B5/06—Arrangements for positively actuating jaws
    • B25B5/061—Arrangements for positively actuating jaws with fluid drive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/38—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by piston and cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/426—Flow control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/455—Control of flow in the feed line, i.e. meter-in control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/46—Control of flow in the return line, i.e. meter-out control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/47—Flow control in one direction only
    • F15B2211/473—Flow control in one direction only without restriction in the reverse direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50554—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure downstream of the pressure control means, e.g. pressure reducing valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/526—Pressure control characterised by the type of actuation electrically or electronically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/57—Control of a differential pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/77—Control of direction of movement of the output member
    • F15B2211/7716—Control of direction of movement of the output member with automatic return

Definitions

  • the invention relates to a differential pressure switching valve according to the preamble of the claim 1.
  • the signal is e.g. in a Machine tool transmitted to a control device to reach an inside a wide range of consumer pressure set to a certain value (Clamping pressure) to report, so that the control device further processing steps can cause. Because the area of action of the first piston is considerable is larger than the area of action of the second piston can be relatively lower Pilot pressure can be used.
  • the first piston is actuated by the released force of the spring arrangement the electrical switch so that the control device transmits a good signal with which the control device can not do anything.
  • the spring arrangement required to ensure an even switching point in the entire setting range.
  • the invention has for its object a differential pressure switching valve at the beginning to create the type mentioned with improved switching behavior.
  • the counter spring is hydraulically switched off, so that the first and second pistons under the influence of the spring arrangement work correctly.
  • the pilot pressure falls below a certain pressure threshold drops, the counter-piston is no longer able to switch off the counter-spring, which only then overcomes the force of the spring arrangement.
  • the spring arrangement is not more able to operate the electrical switch via the first piston, as long as a certain level of the pilot pressure is not available again. On structurally simple way is thus ensured that in the case of pressure conditions at which no pressure monitoring or pressure message is needed, also no message is delivered.
  • the counter spring is automatically switched off when the Change pressure ratios and pressure monitoring is needed. This is useful around an electronic control device of a machine tool is unnecessary spare confusing signals.
  • the counter spring is expediently hydraulically controlled by the pilot pressure Counter piston switched off. This means that the counter spring automatically takes effect, as soon as the pilot pressure has dropped below a predetermined threshold is.
  • the counter spring with the counter piston is structurally simple in the differential pressure switching valve incorporated.
  • a structural simplification is also achieved if the areas of contact with one another are the same.
  • a correct pressure scan is achieved, however, the displacement resistance of the pistons can be higher.
  • the first piston and the counter-piston can only be slide-tight and thus run smoothly in the housing bore. If necessary with slide tightness Any leakage that occurs will return without any interference.
  • the counter spring is appropriately dimensioned so that it reliably Avoid generation of unwanted messages by the electrical switch.
  • the differential pressure switching valve is particularly useful for a machine tool, where the consumer can be completely relieved of pressure. Then the levy a confusing good signal due to the counter spring avoided.
  • An example would be a pair of sheet metal shears in which hold-down devices can be used to reset a workpiece have to record that is being processed.
  • the differential pressure switching valve reports when the set clamping pressure of the hold-down device is reached, so that the higher one Control device issue the command to machine the clamped workpiece can.
  • the hold-down device is returned to the basic position by its return springs the consumer line is depressurized and the pilot pressure also builds up to return.
  • the counter spring would appear again. Thanks to the counter spring, this message is suppressed.
  • a differential pressure switching valve D has a housing 1 with a longitudinal one Housing hole 2 on. At one end of the housing 1 there is an electrical one Switch S with its housing 3, expediently for setting its Switching point adjustable, arranged such that its actuating element 14 approximately lies in the axis of the housing bore 2 and faces the housing bore.
  • a first piston K1 with a large contact surface A1 is displaceably guided, which is designed as a pot piston and has a driver stop 12 on the inside.
  • a spring arrangement F is contained in the interior, which is located on the stopper 10a supports and via a plunger head 11 of a second coaxial piston K2 first piston K1 in Fig.
  • the second piston K2 the pressure surface A2 is significantly smaller than the area of application A1 a seal 27 and a short guide portion 27 'in the plug 10a and protrudes into a chamber 4, which has a throttle 5 with a reference pressure connection 6 connected is.
  • a channel 7 is provided which the housing bore at the level of the pressure surface A1 of the first piston K1 with a pilot pressure connection 8 connects.
  • channels 9 can be provided in the housing 1 be, which lead to a return port R.
  • the first piston K1 sealed with a seal 29 in the housing bore 2 has a plunger 13 on the actuating element 14 of the electrical Switch S is aligned.
  • the plunger 13 passes through a sealing guide 16 in the stopper 15.
  • Between the plug 15 and the first piston K1 are a counter spring G and a counter piston K3 arranged.
  • the counter piston K3 has e.g. the same Action surface A3 as the first piston K1, contains a seal 17 for the Tappet 13, and is even slidable with a seal 28 in the housing bore 2.
  • the counter-piston K3 transmits the force of the support on the plug 15 Counter spring G on the first piston K1, as long as that in the housing bore 2 between the pilot pressure acting on the application areas A1 and A3 is a predetermined one Pressure threshold does not exceed. If the pilot pressure rises above the pressure threshold, then the application area A3 is sufficient for the counter-piston K3 the counter spring G switches off, it goes to the stop with the plug 15.
  • the the first piston uses K1 for its working cycle movement, which he executes in cooperation with the second piston K2 in order to predetermined relation between the pilot pressure at the pilot pressure connection 8 and the reference pressure at the reference pressure connection 6, the actuating element 14 to operate the electrical switch so that the switch emits a signal.
  • the Pilot pressure is set to regulate a certain consumer pressure the pilot pressure in a pressure control valve for the mentioned control function is used.
  • the reference pressure is derived from the actual consumer pressure, which is above the pressure control valve is activated. Only if the predetermined ratio between the reference pressure and the pilot pressure is reached, the signal should be given become.
  • the force of the counter spring G is greater than the force of the spring arrangement F, namely at least by the displacement resistances of pistons K3, K1, K2 and plunger 13 in the seal 16.
  • a hydraulic control device H in FIG. 2 is used, for example, for motion control a hydraulic clamping device N of a machine tool, for example the hold-down device of tin snips.
  • a hydraulic clamping device N of a machine tool for example the hold-down device of tin snips.
  • the jig N are through Springs resettable, one-sided actionable cylinder 21 in parallel via a consumer line 20 connected to the output of a pressure control valve M, the arranged downstream of a 2/2-way seat valve 18 with magnetic actuation and with a Pump line is connected.
  • the valve 18 is part of a directional control valve, the other part also a 2/2-way seat valve 19 with magnetic actuation in one of the Consumer line 20 to the return line R branching drain line 22 is.
  • the Differential pressure switching valve D is with its reference pressure port 8 to one of the consumer line 20 branching control line 25 and with its pilot pressure connection 6 to a pilot line 24 to the pilot side 23 of the pressure control valve M (for example by a proportional magnet on the respective Consumer pressure level is adjustable) connected.
  • the differential pressure switching valve D With the differential pressure switching valve D are the spring arrangement F, the electrical switch S and the return connection R (for leaks) only indicated symbolically.
  • the valve 19 In order to extend the cylinders 21 against their return springs, the valve 19 is in its Blocked position is adjusted while the valve 18 is adjusted to its open position becomes.
  • Pump line P is unregulated Pressure on, which is higher than that at the pressure control valve M by means of the proportional magnet 26 set pressure. Regardless of changes to the unregulated Pressure in the pump line P is from the pressure control valve M in the cylinders 21st the desired pressure is maintained.
  • the differential pressure switching valve D transmits when reached the set clamping pressure with the electrical switch the signal "Tension pressure reached" to a higher-level control device, not shown Machine tool. This then causes further processing steps, e.g. the actuation the sheet metal shear drives.
  • valve 18 In order to relax the hold-down cylinder 21, the valve 18 is first in its Blocked position switched, and then the valve 19 in its open position.
  • the Consumer line 20 is relieved of pressure.
  • Both the reference pressure in the control line 25 and the pilot pressure in the control line 24 are reduced.
  • the spring arrangement F the electrical again when the pilot pressure drops Actuate switch S and the control device receives a signal "clamping pressure reached" to transfer.
  • the counter spring suppresses this message, the control device correctly informed.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Fluid-Driven Valves (AREA)

Description

Die Erfindung betrifft ein Differenzdruck-Schaltventil gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a differential pressure switching valve according to the preamble of the claim 1.

Bei dem aus DE-U-297 10 128 bekannten Differenzdruck-Schaltventil liefert der von dem ersten Kolben betätigbare elektrische Schalter ein Signal, sobald die ersten und zweiten Kolben vorbestimmte von der Differenz zwischen dem Vorsteuerdruck und dem Referenzdruck abhängige Positionen einnehmen. Das Signal wird z.B. in einer Werkzeugmaschine einer Steuereinrichtung übermittelt, um das Erreichen eines innerhalb eines breiten Bereichs auf einen bestimmten Wert eingestellten Verbraucherdrucks (Spanndrucks) zu melden, damit die Steuereinrichtung weitere Bearbeitungsschritte veranlassen kann. Da die Beaufschlagungsfläche des ersten Kolbens erheblich größer als die Beaufschlagungsfläche des zweiten Kolbens ist, kann relativ niedriger Vorsteuerdruck benutzt werden. Wenn jedoch das System druckentlastet wird, und Vorsteuerdruck und Referenzdruck stark abfallen oder nicht mehr vorhanden sind, dann betätigt der erste Kolben durch die freiwerdende Kraft der Federanordnung den elektrischen Schalter, so daß der Steuereinrichtung ein Gut-Signal übermittelt wird, mit dem die Steuereinrichtung nichts anfangen kann. Andererseits wird die Federanordnung benötigt, um einen gleichmäßigen Schaltpunkt im ganzen Einstellbereich zu gewährleisten.In the differential pressure switching valve known from DE-U-297 10 128, the delivers from the first piston actuated electrical switch a signal as soon as the first and second piston predetermined by the difference between the pilot pressure and take positions dependent on the reference pressure. The signal is e.g. in a Machine tool transmitted to a control device to reach an inside a wide range of consumer pressure set to a certain value (Clamping pressure) to report, so that the control device further processing steps can cause. Because the area of action of the first piston is considerable is larger than the area of action of the second piston can be relatively lower Pilot pressure can be used. However, if the system is relieved of pressure, and the pilot pressure and reference pressure drop sharply or no longer exist then the first piston is actuated by the released force of the spring arrangement the electrical switch so that the control device transmits a good signal with which the control device can not do anything. On the other hand, the spring arrangement required to ensure an even switching point in the entire setting range.

Weiterer Stand der Technik ist enthalten in DE-U-85 27 184 und SVESHNIKOV V K: "MATERIALS ON THE MECHANICAL ENGINEERING ENCYCLOPEDIC REFE-RENCE BOOKSPECIAL-PURPOSE HYDRAULIC ASSEMBLY UNITS", RUSSIAN ENGINEERING RESEARCH; Bd. 15, Nr. 11, 1995, Seiten 33-42.Further prior art is contained in DE-U-85 27 184 and SVESHNIKOV V K: "MATERIALS ON THE MECHANICAL ENGINEERING ENCYCLOPEDIC REFE-RENCE BOOKSPECIAL-PURPOSE HYDRAULIC ASSEMBLY UNITS ", RUSSIAN ENGINEERING RESEARCH; Vol. 15, No. 11, 1995, pages 33-42.

Der Erfindung liegt die Aufgabe zugrunde, ein Differenzdruck-Schaltventil der eingangs genannten Art mit verbessertem Schaltverhalten zu schaffen.The invention has for its object a differential pressure switching valve at the beginning to create the type mentioned with improved switching behavior.

Die gestellte Aufgabe wird erfindungsgemäß mit den Merkmalen des Anspruchs 1 gelöst. The object is achieved according to the invention with the features of claim 1 solved.

Solange Druckverhältnisse mit ausreichend hohen Drücken vorliegen, die von dem Differenzdruck-Schaltventil überwacht und zu einer Betätigung oder Nichtbetätigung des elektrischen Schalters genutzt werden, ist die Gegenfeder hydraulisch ausgeschaltet, so daß die ersten und zweiten Kolben unter der Einflußnahme der Federanordnung korrekt arbeiten. Sobald der Vorsteuerdruck unter eine bestimmte Druckschwelle abfällt, vermag der Gegenkolben die Gegenfeder nicht mehr auszuschalten, die erst dann die Kraft der Federanordnung überwindet. Die Federanordnung ist nicht mehr in der Lage den elektrischen Schalter, über den ersten Kolben zu betätigen, solange nicht erneut eine bestimmte Höhe des Vorsteuerdrucks vorhanden ist. Auf baulich einfache Weise wird somit dafür gesorgt, daß bei Druckverhältnissen, bei denen keine Drucküberwachung oder Druckmeldung gebraucht wird, auch keine Meldung abgegeben wird. Die Gegenfeder wird automatisch ausgeschaltet, wenn sich die Druckverhältnisse ändern und die Drucküberwachung gebraucht wird. Dies ist zweckmäßig, um einer elektronischen Steuereinrichtung einer Werkzeugmaschine unnötig verwirrende Signale zu ersparen.As long as there are pressure conditions with sufficiently high pressures that of the Differential pressure switching valve is monitored and actuated or not actuated the electrical switch are used, the counter spring is hydraulically switched off, so that the first and second pistons under the influence of the spring arrangement work correctly. As soon as the pilot pressure falls below a certain pressure threshold drops, the counter-piston is no longer able to switch off the counter-spring, which only then overcomes the force of the spring arrangement. The spring arrangement is not more able to operate the electrical switch via the first piston, as long as a certain level of the pilot pressure is not available again. On structurally simple way is thus ensured that in the case of pressure conditions at which no pressure monitoring or pressure message is needed, also no message is delivered. The counter spring is automatically switched off when the Change pressure ratios and pressure monitoring is needed. This is useful around an electronic control device of a machine tool is unnecessary spare confusing signals.

Zweckmäßig wird die Gegenfeder hydraulisch durch den Vorsteuerdruck über den Gegenkolben ausgeschaltet. Dadurch kommt die Gegenfeder automatisch zur Wirkung, sobald der Vorsteuerdruck unter einen vorbestimmten Schwellwert abgefallen ist.The counter spring is expediently hydraulically controlled by the pilot pressure Counter piston switched off. This means that the counter spring automatically takes effect, as soon as the pilot pressure has dropped below a predetermined threshold is.

Baulich einfach ist die Gegenfeder mit dem Gegenkolben baulich einfach in das Differenzdruck-Schaltventil eingegliedert.The counter spring with the counter piston is structurally simple in the differential pressure switching valve incorporated.

Eine bauliche Vereinfachung wird auch erzielt, wenn die Beaufschlagungsflächen einander gleich sind.A structural simplification is also achieved if the areas of contact with one another are the same.

Bei einer anderen Ausführungsform wird zwar eine korrekte Druckabtastung erzielt, jedoch kann der Verschiebewiderstand der Kolben höher sein. In another embodiment, a correct pressure scan is achieved, however, the displacement resistance of the pistons can be higher.

Um aufgrund eventueller Leckage oder funktionsbedingt auftretender Volumensänderungen keine unerwünschten parasitären Kräfte entstehen zu lassen, sollten die Rückseiten der Kolben zum Rücklauf entlastet sein.In order to avoid any leakage or changes in volume caused by the function to prevent unwanted parasitic forces from developing The back of the pistons must be relieved to return.

Es lassen sich hierbei der erste Kolben und der Gegenkolben nur schieberdicht und damit leichtgängig in der Gehäusebohrung führen. Bei Schieberdichtheit gegebenenfalls auftretende Leckage gelangt ohne störende Einflußnahme zum Rücklauf.The first piston and the counter-piston can only be slide-tight and thus run smoothly in the housing bore. If necessary with slide tightness Any leakage that occurs will return without any interference.

Insgesamt läßt sich eine kompakte Bauform erzielen.Overall, a compact design can be achieved.

In günstiger Weise werden unerwünschte Verluste für den Vorsteuerdruck vermieden.Undesirable losses for the pilot pressure are avoided in a favorable manner.

Zweckmäßig ist die Gegenfeder gerade so dimensioniert, daß sie zuverlässig das Entstehen unerwünschter Meldungen durch den elektrischen Schalter vermeidet.The counter spring is appropriately dimensioned so that it reliably Avoid generation of unwanted messages by the electrical switch.

Das Differenzdruck-Schaltventil ist besonders zweckmäßig für eine Werkzeugmaschine, bei der der Verbraucher vollständig druckentlastbar ist. Dann wird die Abgabe eines verwirrenden Gutsignals aufgrund der Gegenfeder vermieden. Ein Beispiel wäre eine Blechschere, bei der durch Federn rückstellbare Niederhalter ein Werkstück festzuhalten haben, das bearbeitet wird. Das Differenzdruck-Schaltventil meldet, wenn der eingestellte Spanndruck der Niederhalter erreicht ist, damit die übergeordnete Steuereinrichtung den Befehl zum Bearbeiten des gespannten Werkstücks abgeben kann. Wenn die Niederhalter durch ihre Rückstellfedern in die Grundstellung zurückgeführt werden, ist die Verbraucherleitung drucklos und baut sich auch der Vorsteuerdruck zum Rücklauf ab. Wäre die Gegenfeder im Differenzdruck-Schaltventil nicht vorhanden, dann käme es erneut zu der nicht erwünschten Meldung "Spanndruck erreicht". Dank der Gegenfeder wird diese Meldung unterdrückt.The differential pressure switching valve is particularly useful for a machine tool, where the consumer can be completely relieved of pressure. Then the levy a confusing good signal due to the counter spring avoided. An example would be a pair of sheet metal shears in which hold-down devices can be used to reset a workpiece have to record that is being processed. The differential pressure switching valve reports when the set clamping pressure of the hold-down device is reached, so that the higher one Control device issue the command to machine the clamped workpiece can. When the hold-down device is returned to the basic position by its return springs the consumer line is depressurized and the pilot pressure also builds up to return. Would not be the counter spring in the differential pressure switching valve is present, then the undesired message "clamping pressure reached" would appear again. Thanks to the counter spring, this message is suppressed.

Anhand der Zeichnung werden Ausführungsformen des Erfindungsgegenstandes erläutert. Es zeigen:

Fig. 1
einen Längsschnitt durch ein Differenzdruck-Schaltventil in drucklosem Zustand, und
Fig. 2
ein Blockschaltbild einer hydraulischen Steuervorrichtung, in der das Differenzdruck-Schaltventil eine Komponente bildet.
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 differential pressure switching valve in the depressurized state, and
Fig. 2
a block diagram of a hydraulic control device in which the differential pressure switching valve forms a component.

In Fig. 1 weist ein Differenzdruck-Schaltventil D ein Gehäuse 1 mit einer längsdurchgehenden Gehäusebohrung 2 auf. An einer Stirnseite des Gehäuses 1 ist ein elektrischer Schalter S mit seinem Gehäuse 3, zweckmäßigerweise zur Einstellung seines Schaltpunktes verstellbar, angeordnet, derart, daß sein Betätigungselement 14 in etwa in der Achse der Gehäusebohrung 2 liegt und zur Gehäusebohrung weist. In der Gehäusebohrung 2, die an beiden Enden durch Stopfen 10a, 10b, 15 verschlossen ist, ist ein erster Kolben K1 mit großer Beaufschlagungsfläche A1 verschiebbar geführt, der als Topfkolben ausgebildet ist und innen einen Mitnehmeranschlag 12 besitzt. Ferner ist im Innenraum eine Federanordung F enthalten, die sich am Stopfen 10a abstützt und über einen Stößelkopf 11 eines zweiten koaxialen Kolbens K2 den ersten Kolben K1 in Fig. 1 nach oben belastet. Der zweite Kolben K2, dessen Beaufschlagungsfläche A2 wesentlich kleiner als die Beaufschlagungsfläche A1 ist, durchsetzt eine Dichtung 27 und einen kurzen Führungsabschnitt 27' im Stopfen 10a und ragt in eine Kammer 4, die über eine Drossel 5 mit einem Referenzdruck-Anschluß 6 verbunden ist. Im Gehäuse 1 ist ein Kanal 7 vorgesehen, der die Gehäusebohrung auf der Höhe der Beaufschlagungsfläche A1 des ersten Kolbens K1 mit einem Vorsteuerdruck-Anschluß 8 verbindet. Ferner können Kanäle 9 im Gehäuse 1 vorgesehen sein, die zu einem Rücklaufanschluß R führen.In Fig. 1, a differential pressure switching valve D has a housing 1 with a longitudinal one Housing hole 2 on. At one end of the housing 1 there is an electrical one Switch S with its housing 3, expediently for setting its Switching point adjustable, arranged such that its actuating element 14 approximately lies in the axis of the housing bore 2 and faces the housing bore. In the Housing bore 2, which is closed at both ends by plugs 10a, 10b, 15 a first piston K1 with a large contact surface A1 is displaceably guided, which is designed as a pot piston and has a driver stop 12 on the inside. Furthermore, a spring arrangement F is contained in the interior, which is located on the stopper 10a supports and via a plunger head 11 of a second coaxial piston K2 first piston K1 in Fig. 1 loaded upwards. The second piston K2, the pressure surface A2 is significantly smaller than the area of application A1 a seal 27 and a short guide portion 27 'in the plug 10a and protrudes into a chamber 4, which has a throttle 5 with a reference pressure connection 6 connected is. In the housing 1, a channel 7 is provided which the housing bore at the level of the pressure surface A1 of the first piston K1 with a pilot pressure connection 8 connects. Furthermore, channels 9 can be provided in the housing 1 be, which lead to a return port R.

Der erste, mit einer Dichtung 29 in der Gehäusebohrung 2 abgedichtete Kolben K1 weist einen Stößel 13 auf, der auf das Betätigungselement 14 des elektrischen Schalters S ausgerichtet ist. Der Stößel 13 durchsetzt eine Dichtführung 16 im Stopfen 15. Zwischen dem Stopfen 15 und dem ersten Kolben K1 sind eine Gegenfeder G und ein Gegenkolben K3 angeordnet. Der Gegenkolben K3 besitzt z.B. die gleiche Beaufschlagungsfläche A3 wie der erste Kolben K1, enthält eine Dichtung 17 für den Stößel 13, und ist selbst mit einer Dichtung 28 in der Gehäusebohrung 2 verschieblich. Der Gegenkolben K3 überträgt die Kraft der sich am Stopfen 15 abstützenden Gegenfeder G auf den ersten Kolben K1, solange der in der Gehäusebohrung 2 zwischen den Beaufschlagungsflächen A1 und A3 wirkende Vorsteuerdruck eine vorbestimmte Druckschwelle nicht überschreitet. Steigt der Vorsteuerdruck über die Druckschwelle, dann reicht die Beaufschlagungsfläche A3 aus, damit der Gegenkolben K3 die Gegenfeder G ausschaltet, wobei er auf Anschlag mit dem Stopfen 15 geht. Den dabei freigemachten Hubweg nutzt der erste Kolben K1 für seine Arbeitsspielbewegung, die er im Zusammenspiel mit dem zweiten Kolben K2 ausführt, um bei einer vorbestimmten Relation zwischen dem Vorsteuerdruck am Vorsteuerdruck-Anschluß 8 und dem Referenzdruck am Referenzdruck-Anschluß 6 das Betätigungselement 14 des elektrischen Schalters so zu betätigen, daß der Schalter ein Signal abgibt. Der Vorsteuerdruck wird eingestellt, um einen bestimmten Verbraucherdruck einzuregeln, wobei der Vorsteuerdruck in einem Druckregelventil für die erwähnte Regelfunktion verwendet wird. Der Referenzdruck ist abgeleitet vom Ist-Verbraucherdruck, der über das Druckregelventil eingesteuert ist. Nur wenn das vorbestimmte Verhältnis zwischen dem Referenzdruck und dem Vorsteuerdruck erreicht ist, soll das Signal abgegeben werden.The first piston K1 sealed with a seal 29 in the housing bore 2 has a plunger 13 on the actuating element 14 of the electrical Switch S is aligned. The plunger 13 passes through a sealing guide 16 in the stopper 15. Between the plug 15 and the first piston K1 are a counter spring G and a counter piston K3 arranged. The counter piston K3 has e.g. the same Action surface A3 as the first piston K1, contains a seal 17 for the Tappet 13, and is even slidable with a seal 28 in the housing bore 2. The counter-piston K3 transmits the force of the support on the plug 15 Counter spring G on the first piston K1, as long as that in the housing bore 2 between the pilot pressure acting on the application areas A1 and A3 is a predetermined one Pressure threshold does not exceed. If the pilot pressure rises above the pressure threshold, then the application area A3 is sufficient for the counter-piston K3 the counter spring G switches off, it goes to the stop with the plug 15. The the first piston uses K1 for its working cycle movement, which he executes in cooperation with the second piston K2 in order to predetermined relation between the pilot pressure at the pilot pressure connection 8 and the reference pressure at the reference pressure connection 6, the actuating element 14 to operate the electrical switch so that the switch emits a signal. The Pilot pressure is set to regulate a certain consumer pressure the pilot pressure in a pressure control valve for the mentioned control function is used. The reference pressure is derived from the actual consumer pressure, which is above the pressure control valve is activated. Only if the predetermined ratio between the reference pressure and the pilot pressure is reached, the signal should be given become.

Die Zwischenräume zwischen dem Stopfen 15 und dem Gegenkolben K3 und zwischen dem ersten Kolben K1 und dem Stopfen 10a sind über die Kanäle 9 im Gehäuse 1 mit dem Rücklauf R verbunden. Dadurch können in den Kolben K3, K1 die Dichtungen 28, 29 weggelassen werden, so daß die Kolben K1, K3 nur schieberdicht geführt werden. Dies verringert deren Verschiebewiderstände.The spaces between the plug 15 and the counter-piston K3 and between the first piston K1 and the plug 10a are via the channels 9 in the housing 1 connected to the return R. This allows the piston K3, K1 Seals 28, 29 are omitted, so that the pistons K1, K3 only slide-tight be performed. This reduces their resistance to displacement.

Die Kraft der Gegenfeder G ist größer als die Kraft der Federanordnung F, und zwar mindestens um die Verschiebewiderstände der Kolben K3, K1, K2 und des Stößel 13 in der Dichtung 16.The force of the counter spring G is greater than the force of the spring arrangement F, namely at least by the displacement resistances of pistons K3, K1, K2 and plunger 13 in the seal 16.

Eine hydraulische Steuervorrichtung H in Fig. 2 dient beispielsweise zur Bewegungssteuerung einer hydraulischen Spannvorrichtung N einer Werkzeugmaschine, beispielsweise der Niederhalter einer Blechschere. In der Spannvorrichtung N sind durch Federn rückstellbare, einseitig beaufschlagbare Zylinder 21 parallel über eine Verbraucherleitung 20 an den Ausgang eines Druckregelventils M angeschlossen, das stromab eines 2/2-Wegesitzventils 18 mit Magnetbetätigung angeordnet und mit einer Pumpenleitung verbunden ist. Das Ventil 18 ist Teil eines Wegesteuerventils, dessen anderer Teil ebenfalls ein 2/2-Wegesitzventil 19 mit Magnetbetätigung in einer von der Verbraucherleitung 20 zur Rücklaufleitung R abzweigenden Ablaßleitung 22 ist. Das Differenzdruck-Schaltventil D ist mit seinem Referenzdruck-Anschluß 8 an eine von der Verbraucherleitung 20 abzweigende Steuerleitung 25 und mit seinem Vorsteuerdruck-Anschluß 6 an eine Vorsteuerleitung 24 zur Vorsteuerseite 23 des Druckregelventils M (das beispielsweise durch einen Proportionalmagneten auf die jeweilige Verbraucherdruckhöhe einstellbar ist) angeschlossen. Beim Differenzdruck-Schaltventil D sind die Federanordnung F, der elektrische Schalter S und der Rücklaufanschluß R (für Leckagen) nur symbolisch angedeutet.A hydraulic control device H in FIG. 2 is used, for example, for motion control a hydraulic clamping device N of a machine tool, for example the hold-down device of tin snips. In the jig N are through Springs resettable, one-sided actionable cylinder 21 in parallel via a consumer line 20 connected to the output of a pressure control valve M, the arranged downstream of a 2/2-way seat valve 18 with magnetic actuation and with a Pump line is connected. The valve 18 is part of a directional control valve, the other part also a 2/2-way seat valve 19 with magnetic actuation in one of the Consumer line 20 to the return line R branching drain line 22 is. The Differential pressure switching valve D is with its reference pressure port 8 to one of the consumer line 20 branching control line 25 and with its pilot pressure connection 6 to a pilot line 24 to the pilot side 23 of the pressure control valve M (for example by a proportional magnet on the respective Consumer pressure level is adjustable) connected. With the differential pressure switching valve D are the spring arrangement F, the electrical switch S and the return connection R (for leaks) only indicated symbolically.

Um die Zylinder 21 gegen ihre Rückstellfedern auszufahren, ist das Ventil 19 in seine Absperrstellung verstellt, während das Ventil 18 in seine Durchgangsstellung verstellt wird. Über den Proportionalmagneten 26 wird die Höhe des Drucks in der Verbraucherleitung 20 bzw. in den Zylindern 21 eingestellt. In der Pumpenleitung P steht ungeregelter Druck an, der höher ist, als der am Druckregelventil M mittels des Proportionalmagneten 26 eingestellte Druck. Unabhängig von Änderungen des ungeregelten Drucks in der Pumpenleitung P wird vom Druckregelventil M in den Zylindern 21 der gewünschte Druck gehalten. Das Differenzdruck-Schaltventil D übermittelt bei Erreichen des eingestellten Spanndruckes mit dem elektrischen Schalter das Signal "Spanndruck erreicht" an eine übergeordnete, nicht gezeigte Steuereinrichtung der Werkzeugmaschine. Diese veranlaßt dann weitere Bearbeitungsschritte, z.B. die Betätigung der Blechscherenantriebe.In order to extend the cylinders 21 against their return springs, the valve 19 is in its Blocked position is adjusted while the valve 18 is adjusted to its open position becomes. About the proportional magnet 26, the level of pressure in the consumer line 20 or set in the cylinders 21. Pump line P is unregulated Pressure on, which is higher than that at the pressure control valve M by means of the proportional magnet 26 set pressure. Regardless of changes to the unregulated Pressure in the pump line P is from the pressure control valve M in the cylinders 21st the desired pressure is maintained. The differential pressure switching valve D transmits when reached the set clamping pressure with the electrical switch the signal "Tension pressure reached" to a higher-level control device, not shown Machine tool. This then causes further processing steps, e.g. the actuation the sheet metal shear drives.

Um die Niederhalterzylinder 21 zu entspannen, wird zunächst das Ventil 18 in seine Absperrstellung geschaltet, und dann das Ventil 19 in seine Durchgangsstellung. Die Verbraucherleitung 20 wird druckentlastet. Sowohl der Referenzdruck in der Steuerleitung 25 als auch der Vorsteuerdruck in der Steuerleitung 24 werden abgebaut. Wäre nun die Gegenfeder im Differenzdruck-Schaltventil D nicht vorhanden, dann würde die Federanordnung F beim Absinken des Vorsteuerdrucks erneut den elektrischen Schalter S betätigen und der Steuereinrichtung ein Signal "Spanndruck erreicht" übermitteln. Da die Gegenfeder jedoch diese Meldung unterdrückt, wird die Steuereinrichtung korrekt informiert.In order to relax the hold-down cylinder 21, the valve 18 is first in its Blocked position switched, and then the valve 19 in its open position. The Consumer line 20 is relieved of pressure. Both the reference pressure in the control line 25 and the pilot pressure in the control line 24 are reduced. Would now the counter spring in the differential pressure switching valve D does not exist, then would the spring arrangement F the electrical again when the pilot pressure drops Actuate switch S and the control device receives a signal "clamping pressure reached" to transfer. However, since the counter spring suppresses this message, the control device correctly informed.

Obwohl das Differenzdruck-Schaltventil in Verbindung mit einer speziellen Art einer Werkzeugmaschine erläutert wurde, ist darauf hinzuweisen, daß es für andere Spannvorrichtungen in in anderen Werkzeugmaschinen ebenfalls verwendbar ist, bei denen bei Absinken des Vorsteuerdrucks unter einen bestimmten Schwellwert ein Signal vermieden werden soll.Although the differential pressure switching valve in connection with a special kind of Machine tool has been explained, it should be noted that it is for others Clamping devices can also be used in other machine tools a signal if the pilot pressure drops below a certain threshold should be avoided.

Claims (11)

  1. Differential-pressure control valve (D), in particular for a hydraulic machine-tool clamping device (N), having a first piston (K1) which can be acted upon in an opposed manner to a coaxial, second piston (K2) which is coupled to the first piston (K1), the application area (A1) of the first piston (K1), which area is loaded by a pilot-control pressure produced for setting the consumer pressure, being larger than the application area (A2) of the second piston (K2), which area is loaded by a reference pressure derived from a consumer pressure, having a spring arrangement (F) which acts upon the two pistons (K1, K2) in the loading direction of the reference pressure, and having an electric switch (S) which can be actuated as a function of the position of the first piston (K1), characterized in that a counterspring (G) is provided which subjects at least the first piston (K1) to a counterforce which overcomes the force of the spring arrangement (F), and in that the counterspring (G) can be disengaged hydraulically by means of an opposed piston (K3).
  2. Differential-pressure control valve according to Claim 1, characterized in that the opposed piston (K3) can be adjusted by means of the pilot-control pressure which loads the first piston (K1), into a position disengaging the counterspring (G).
  3. Differential-pressure control valve according to Claim 1, characterized in that the counterspring (G) is provided in a housing bore (2), which contains the first piston (K1), on the opposed piston (K3) and loads the first piston (K1) via the opposed piston (K3).
  4. Differential-pressure control valve according to Claim 1, characterized in that the application area (A3) of the opposed piston (K3) corresponds to that of the first piston (K1).
  5. Differential-pressure control valve according to Claim 3, characterized in that the first piston (K1) and the opposed piston (K3) can be displaced in the housing bore (2) in a sealed manner with sealing elements (29, 28).
  6. Differential-pressure control valve according to Claim 1, characterized in that the rear sides of the first piston (K1) and of the opposed piston (K3), which sides face away from the application areas (A1, A3), are pressure-relieved, preferably to a return connection (R).
  7. Differential-pressure control valve according to at least one of Claims 3 and 6, characterized in that the first piston (K1) and the opposed piston (K3) are guided in the housing bore (2) in a manner such that they just fit for sliding purposes.
  8. Differential-pressure control valve according to Claim 1, characterized in that the first piston (K1) actuates the electric switch (S) via a tappet (13) which is led out of the housing bore (2) in a sealed manner, and in that the tappet (13) passes through the opposed piston (K3), and preferably also the counterspring (G).
  9. Differential-pressure control valve according to Claim 8, characterized in that a seal (17) for the tappet (13) is provided in the opposed piston (K3).
  10. Differential-pressure control valve according to at least one of the preceding Claims 8 or 9, characterized in that the counterforce of the counterspring (G) is greater than the force of the spring arrangement (F) at least by the displacement resistances of the opposed piston (K3) and of the first piston (K1) plus the displacement resistance of the tappet (13) in its sealed guide (16) in the housing bore.
  11. Differential-pressure control valve according to at least one of the preceding claims, characterized in that the differential-pressure control valve (D), as pressure detector, is connected to the consumer line (20) of a hydraulic motor (21) of the clamping device (N) of a machine tool, which line can be charged and discharged via a directional control valve (W), the directional control valve (W), in its basic position, discharging the consumer line pressure and the pilot-control pressure of a pilot-controlled pressure-regulating valve (M), which is assigned to the directional control valve, to the return connection (R), and in that the electric switch (S) is connected for the purpose of transmitting signals to a higher-order control device of the machine tool.
EP99107503A 1998-06-03 1999-04-14 Differential pressure switching valve with electrical switch Expired - Lifetime EP0962661B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE29809936U DE29809936U1 (en) 1998-06-03 1998-06-03 Differential pressure switching valve with electrical switch
DE29809936U 1998-06-03

Publications (2)

Publication Number Publication Date
EP0962661A1 EP0962661A1 (en) 1999-12-08
EP0962661B1 true EP0962661B1 (en) 2003-12-10

Family

ID=8058040

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99107503A Expired - Lifetime EP0962661B1 (en) 1998-06-03 1999-04-14 Differential pressure switching valve with electrical switch

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Country Link
EP (1) EP0962661B1 (en)
DE (2) DE29809936U1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9915309D0 (en) * 1999-06-30 1999-09-01 Lucas Ind Plc Valve

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8527184U1 (en) 1985-09-24 1986-01-09 Vöhringer, Karl, 7554 Kuppenheim Pressure control valve
DE29710128U1 (en) 1997-06-10 1997-08-14 Heilmeier & Weinlein Fabrik für Oel-Hydraulik GmbH & Co KG, 81673 München Differential pressure switching valve

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EP0962661A1 (en) 1999-12-08
DE59907989D1 (en) 2004-01-22

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