EP0083688B1 - Electro-hydraulic pilot-operated proportional throttle valve - Google Patents

Electro-hydraulic pilot-operated proportional throttle valve Download PDF

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Publication number
EP0083688B1
EP0083688B1 EP82108826A EP82108826A EP0083688B1 EP 0083688 B1 EP0083688 B1 EP 0083688B1 EP 82108826 A EP82108826 A EP 82108826A EP 82108826 A EP82108826 A EP 82108826A EP 0083688 B1 EP0083688 B1 EP 0083688B1
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EP
European Patent Office
Prior art keywords
piston
differential
choke
valve
pilot
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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
Application number
EP82108826A
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German (de)
French (fr)
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EP0083688A2 (en
EP0083688A3 (en
Inventor
Karl-Heinz Dr. Post
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Oerlikon Barmag AG
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Barmag Barmer Maschinenfabrik AG
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Publication of EP0083688A2 publication Critical patent/EP0083688A2/en
Publication of EP0083688A3 publication Critical patent/EP0083688A3/en
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    • 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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/042—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure
    • F15B13/043—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves
    • F15B13/0435—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor operated by fluid pressure with electrically-controlled pilot valves the pilot valves being sliding valves

Definitions

  • the invention relates to an electro-hydraulically pilot-controlled proportional throttle valve, the throttle piston of which is mechanically connected to a double-acting control piston which can be controlled hydraulically by an electromagnetically actuated pilot valve on returning the position of the throttle piston to the pilot valve.
  • This proportional throttle valve is known from French FR-A-2 235 300. With this valve, the throttle piston is guided at both ends in pressure chambers which can be acted upon by a pilot valve with different pilot pressures. This causes the throttling of oil flows with the axial displacement of the throttle piston.
  • the pilot valve of the pilot valve is connected to the throttle piston by a spring rod. As a result, the pilot force exerted on the throttle piston is returned to the position of the pilot spool.
  • This valve construction cannot be used for a 2-way cartridge valve.
  • a proportional throttle valve which consists of a 2-way cartridge valve which is acted upon by a control pressure on the side facing away from the pump pressure and by a closing spring in the closing direction.
  • the control pressure is controlled by a pilot spool depending on an electro-magnetically input command variable, the current throttle piston position is returned to the pilot spool by a helical spring clamped between the two ("Oil hydraulics and pneumatics" 1981, page 35).
  • this throttle valve works too slowly in the closing direction for some applications if there is no pressure difference between the oil inlet and the oil outlet.
  • the pilot solenoid is at full pump pressure.
  • the throttle valve according to the invention is also an electro-hydraulic pilot-controlled proportional throttle valve, which is characterized in that the throttle piston is actuated by means of a differential piston.
  • the differential piston is firmly connected to the throttle piston by a piston rod.
  • the differential piston is guided in a differential cylinder and is acted upon on both sides with the control pressures given by the pilot valve and its position in a control loop is fed back to the pilot.
  • the diameter of the differential piston is larger than the throttle piston.
  • the piston rod-side ring surface of the differential piston delimits the opening-side control pressure chamber of the differential cylinder with the second end face of the throttle piston, and the ring surface facing away from the differential piston, together with a locking piston / relief piston arrangement, delimits the closing-side control pressure chamber of the differential cylinder.
  • the locking piston / relief piston arrangement has the same diameter as the throttle piston and is acted upon on the end face facing away from the differential piston with the same working pressure as the first end face of the throttle piston.
  • the mechanical position feedback is preferably done by a spring supported between the throttle piston and the pilot spool.
  • Throttle valves the throttle piston of which is connected to a differential piston
  • US Pat. No. 3,604,459 shows a throttle valve, the throttle piston of which is connected to a larger piston.
  • this valve has no electro-hydraulic pilot control with feedback and the valve only acts as an on / off valve, without the possibility of a constant adjustment of the throttle point.
  • the differential pistons shown in DE-B 2112 813 and DE-A 2 533 829 also lack the possibility of actuating these 2-way cartridge valves. Finally, there is no mechanical position feedback between the throttle piston and the pilot valve.
  • the throttle piston and pilot spool are movable parallel to one another, and the spring supported between the two is a spring rod which is firmly clamped either on the throttle piston, on the piston rod or on the pilot spool.
  • the spring rod avoids a common disadvantage of the coil springs, fatigue.
  • a pressure relief bore can penetrate the throttle piston, piston rod and differential piston and open into a counterpressure chamber sealed by a pressure relief piston.
  • the differential piston can lie in a common differential cylinder, the effective area difference on the closing side from the relief piston being greater than the area difference on the opening side.
  • the solution according to the invention ensures that the actuation of the throttle piston in both directions depends solely on the pilot control. This ensures that the throttle valve closes reliably even when there are no significant pressure differences in the conveyor system. Another advantage is the fact that the throttle valve is useful and effective in both flow directions.
  • the proportional valve 1 has a throttle piston 5, which controls an oil flow in the direction of passage 4.1 or 4.2.
  • This throttle piston is firmly connected to the differential piston 7 by piston rod 6.
  • the differential piston slides in the differential cylinder 23, which is delimited on the closing side 21 by piston surface 16 on the locking piston 20 and on the opening side 22 by piston surface 17 on the throttle piston 5.
  • the pressure relief piston 13 is seated in the counterpressure chamber 15, which is connected to the end face of the throttle piston via a pressure relief duct 12 and is so large that on the unit comprising the throttle piston, piston rod and pressure relief piston the hydraulic medium caused by the medium is balanced Forces occur in the direction of movement of the piston rod.
  • a pilot spool 3 moved by means of an electromagnet 2 can be moved parallel to the unit comprising throttle piston 5, piston rod 6, differential piston 7 and pressure relief piston 13 and - initially - assumes a position (current) corresponding to the pilot signal (current) given to the electromagnet 2, as a result of which one of the two control pressure lines 8 , 9 to the opening side 22 or closing side 21 of the differential cylinder 23 is released; the differential piston moves accordingly and thus the throttle piston.
  • the spring rod exerts one force on the pilot spool on the one hand and the throttle piston on the other Restoring force that is in balance with the magnetic force on the pilot spool on the one hand and the hydraulic force on the differential piston on the other.
  • the throttle piston position is returned to the pilot control.
  • the position of the pilot spool 3 is corrected in accordance with the position of the throttle piston 5 in relation to the pilot signal.
  • the area ratios in the differential pistons are important.
  • the piston surface 10 acts in the closing direction, reduced by the piston surface 16 on the locking piston 20. This surface difference is greater than the surface 14 effective in the opening direction, reduced by the surface 17 on the throttle piston.
  • the pilot pressure is effective via channel 18, connecting channel 19 and leaks both on the piston surface 10 and on the counter surface 14. Because of the area ratio, the throttle piston is pressed in the closing direction. If the electromagnet 2 is excited to open the throttle piston 5 so that the pilot spool moves downward (drawing), the annular space 26 and the channel 8 are connected to the connecting channel 19 and the annular channel 27 to the drain (not shown here) to the tank.
  • the valve according to the invention has the advantage that it can be controlled hydraulically, but independently of the medium and its pressure.
  • the pilot pressure channel 18 is connected to a suitable pressure source that delivers a sufficiently high pressure. This enables safe opening and closing at high speeds, even if the throttle valve controls a medium with very low pressure.
  • the pilot pressure channel (18) can also be connected to one of the lines between which the throttle piston controls the flow. It is worth mentioning that even relatively low system pressures are sufficient, since the closing speed and closing force can also be influenced by specifying the area ratio on the differential piston.
  • the valve has the further advantage that it can be flowed through in both directions (arrows 4.1 and 4.2).
  • FIG. 2 shows a modification of the throttle valve according to FIG. 1, with the same structure and the same properties.
  • the throttle valve can be flowed through in the two flow directions (arrow 4.1 and 4.2).
  • Special measures also ensure that the switching speed and the leak-free seal of the throttle piston are guaranteed both with very small pressure differences between the inlet and outlet (i.e. especially with large flow rates) and with pressure drop in one of the lines 28, 29.
  • Fig. 2 it is shown in Fig. 2 that the magnet 2 has a plunger 30 which acts on the pilot valve 3. Also shown is the tank channel 31 which, through the tank bridge 32, depressurises the pilot cylinder at both ends.
  • the pilot valve acts as a hydraulic bridge (Wheatstone measuring bridge), by means of which different control pressures are generated in the pilot channels 8 and 9 for actuating the differential piston 7. In contrast to the exemplary embodiment according to FIG. 1, this acts on the throttle piston 5 2 in Counter pressure chamber 15 accommodated spring 33 in the closing direction. This achieves the following: It may be desirable to constantly load the closing side 21 of the differential piston with a low pressure.
  • the magnet 2 and pilot spool 3 are set so that there is a small - not representable - gap on the piston collar 25 constantly and also in the zero position of the pilot valve or closed position of the throttle piston 5, through which a small oil flow from the connecting channel 19 to the Closing side of the differential piston 7 arrives.
  • this small gap means a slight displacement of the pilot spool 3 upwards and thus also a correspondingly small deflection of the spring 11, combined with an upwardly directed small spring force.
  • the spring 32 now serves the purpose of compensating for this spring force, which acts undesirably in the opening direction of the throttle piston 5.
  • Fig. 2 it is also shown that the pilot pressure channel 18 is alternately acted upon by the pressure of the lines 28 or 29.
  • a shuttle valve 34 is provided. Its inputs are connected to line 29 on the other hand.
  • the central outlet 35 of the shuttle valve 34 leads into the pilot pressure channel 18.
  • the shuttle valve 34 causes the higher pressure of the lines 28 or 29 to be present in the pilot pressure channel 18. If the pressure is equal, both pressures of the lines 28, 29 are equally effective. When changing the current directions (arrows 4.1, 4.2), the control pressure is automatically switched.
  • the pilot valve is also supplied with the required pressure oil when one of the lines 28 or 29 is depressurized, e.g. by connecting it to the tank.
  • any other pressure-dependent switchable valve can be used.
  • the shuttle valve is characterized by its robust and simple construction.
  • Fig. 3 shows an embodiment in which only one current direction (arrow 4.1) is possible.
  • the control pressure is always taken from line 29 via the central pressure relief channel 12.
  • FIGS. 1 and 2 the advantage of the valves according to FIGS. 1 and 2 is also retained here:
  • This valve is also independent of the pressure difference between lines 29 and 28.
  • the closing force and closing speed also depend on the surface conditions on the differential piston 7, so that even low system pressures are sufficient for pilot control.
  • the seating force can also be promoted in that the closing side of the differential piston 7 is pressurized even when the throttle piston or pilot valve is in the zero position.
  • This can - as described in Fig. 2 - happen that magnet 2 and pilot spool 3 are in turn adjusted so that in the zero position of the pilot spool 3 on the piston collar 25 a small gap for connecting the control pressure line 9 to the connecting channel 19 is opened.
  • a relatively weak compression spring 36 is provided for the slight displacement of the fore). Otherwise, the throttle valve according to FIGS.
  • the pressure relief channel does not have to be in the piston rod. It can also extend parallel to it in the hanger from the channel 29 into the counter-pressure chamber 15, so that the two equally effective piston surfaces at the ends of the piston rod, i.e. the end face of the throttle piston 5 and the effective piston surface of the pressure relief piston 15 (Fig. 1; Fig . 2) or the locking piston 20 (Fig. 3) are pressure balanced.

Description

Die Erfindung betrifft ein elektro-hydraulisch vorgesteuertes Proportionaldrosselventil, dessen Drosselkolben mit einem doppelt wirkenden Stellkolben mechanisch verbunden ist, der hydraulisch durch einen elektro-magnetisch betätigten Vorsteuerschieber bei Rückführung der Stellung des Drosselkolbens auf den Vorsteuerschieber steuerbar ist.The invention relates to an electro-hydraulically pilot-controlled proportional throttle valve, the throttle piston of which is mechanically connected to a double-acting control piston which can be controlled hydraulically by an electromagnetically actuated pilot valve on returning the position of the throttle piston to the pilot valve.

Dieses Proportionaldrosselventil ist durch die französische FR-A- 2 235 300 bekannt. Bei diesem Ventil wird der Drosselkolben an seinen beiden Enden in Druckkammern geführt, die von einem Vorsteuerventil aus mit unterschiedlichen Vorsteuerdrücken beaufschlagt werden können. Hierdurch wird mit der axialen Verschiebung des Drosselkolbens die Drosselung von Ölströmen bewirkt. Der Vorsteuerschieber des Vorsteuerventils ist mit dem Drosselkolben durch einen Federstab verbunden. Dadurch wird die auf den Drosselkolben ausgeübte Vorsteuerkraft auf die Stellung des Vorsteuerschiebers zurückgeführt.This proportional throttle valve is known from French FR-A-2 235 300. With this valve, the throttle piston is guided at both ends in pressure chambers which can be acted upon by a pilot valve with different pilot pressures. This causes the throttling of oil flows with the axial displacement of the throttle piston. The pilot valve of the pilot valve is connected to the throttle piston by a spring rod. As a result, the pilot force exerted on the throttle piston is returned to the position of the pilot spool.

Diese Ventilkonstruktion ist nicht für ein 2-Wege-Einbauventil brauchbar.This valve construction cannot be used for a 2-way cartridge valve.

Bekannt ist zwar ein Proportionaldrosselventil, das aus einem 2-Wege-Einbauventil besteht, das auf der vom Pumpendruck abgewandten Seite mit einem Steuerdruck und in Schließrichtung mit einer Schließfeder beaufschlagt wird. Der Steuerdruck ist dabei durch einen Vorsteuerschieber in Abhängigkeit von einer elektro-magnetisch eingegebenen Führungsgröße gesteuert, die Rückführung der momentanen Drosselkolbenstellung auf den Vorsteuerschieber erfolgt durch eine zwischen beiden aufgespannte Schraubenfeder ("Ölhydraulik und Pneumatik" 1981, Seite 35).A proportional throttle valve is known which consists of a 2-way cartridge valve which is acted upon by a control pressure on the side facing away from the pump pressure and by a closing spring in the closing direction. The control pressure is controlled by a pilot spool depending on an electro-magnetically input command variable, the current throttle piston position is returned to the pilot spool by a helical spring clamped between the two ("Oil hydraulics and pneumatics" 1981, page 35).

Wegen der relativ geringen Kraft der Schließfeder arbeitet dieses Drosselventil in Schließrichtung für manche Einsatzzwecke zu träge, wenn zwischen Ölzulauf und Ölablauf keine Druckdifferenz vorhanden ist. Außerdem ist das Problem zu lösen, daß der Vorsteuermagnet am vollen Pumpendruck anliegt.Because of the relatively low force of the closing spring, this throttle valve works too slowly in the closing direction for some applications if there is no pressure difference between the oil inlet and the oil outlet. In addition, the problem is solved that the pilot solenoid is at full pump pressure.

Das Drosselventil nach der Erfindung ist ebenfalls ein elektro-hydraulisch vorgesteuertes Proportionaldrosselventil, welches sich dadurch auszeichnet, daß der Drosselkolben mittels eines Differentialkolbens betätigt wird. Der Differentialkolben ist durch eine Kolbenstange fest mit dem Drosselkolben verbunden. Der Differentialkolben ist in einem Differentialzylinder geführt und wird auf seinen beiden Seiten mit den durch den Vorsteuerschieber aufgegebenen Steuerdrücken beaufschlagt und seine Stellung in einem Regelkreis auf die Vorsteuerung zurückgeführt. Dabei ist der Durchmesser des Differentialkolbens größer als der Drosselkolben. Die kolbenstangenseitige Ringfläche des Differentialkolbens begrenzt mit der zweiten Stirnseite des Drosselkolbens die öffnungsseitige Steuerdruckkammer des Differentialzylinders, und die von dem Differentialkolben abgewandte Ringfläche begrenzt gemeinsam mit einer Sperrkolben-/ Entlastungskolbenanordnung die schließseitige Steuerdruckkammer des Differentialzylinders. Die Sperrkolben- /Entlastungskolbenanordnung hat denselben Durchmesser wie der Drosselkolben und ist auf der von dem Differentialkolben abgewandten Stirnfläche mit dem gleichen Arbeitsdruck wie die erste Stirnseite des Drosselkolbens beaufschlagt.The throttle valve according to the invention is also an electro-hydraulic pilot-controlled proportional throttle valve, which is characterized in that the throttle piston is actuated by means of a differential piston. The differential piston is firmly connected to the throttle piston by a piston rod. The differential piston is guided in a differential cylinder and is acted upon on both sides with the control pressures given by the pilot valve and its position in a control loop is fed back to the pilot. The diameter of the differential piston is larger than the throttle piston. The piston rod-side ring surface of the differential piston delimits the opening-side control pressure chamber of the differential cylinder with the second end face of the throttle piston, and the ring surface facing away from the differential piston, together with a locking piston / relief piston arrangement, delimits the closing-side control pressure chamber of the differential cylinder. The locking piston / relief piston arrangement has the same diameter as the throttle piston and is acted upon on the end face facing away from the differential piston with the same working pressure as the first end face of the throttle piston.

Die mechanische Stellungsrückführung geschieht vorzugsweise durch eine zwischen dem Drosselkolben und dem Vorsteuerschieber abgestützte Feder.The mechanical position feedback is preferably done by a spring supported between the throttle piston and the pilot spool.

Zwar sind Drosselventile, deren Drosselkolben mit einem Differentialkolben verbunden ist, bereits bekannt. So zeigt die US-PS 3,604,459 ein Drosselventil, dessen Drosselkolben mit einem größeren Kolben verbunden ist. Dieses Ventil weist jedoch keine elektro-hydraulische Vorsteuerung mit Rückführung auf und das Ventil wirkt lediglich als Ein-/Aus-Ventil, ohne daß die Möglichkeit einer stetigen Verstellung der Drosselstelle gegeben wäare. Bei den in der DE-B 2112 813 und der DE-A 2 533 829 gezeigten Differentialkolben fehlt ebenfalls die Möglichkeit, mit diesen 2-Wege-Einbauventile zu betätigen. Schließlich ist auch keine mechanische Stellungsrückführung zwischen Drosselkolben und Vorsteuerschieber vorgesehen.Throttle valves, the throttle piston of which is connected to a differential piston, are already known. For example, US Pat. No. 3,604,459 shows a throttle valve, the throttle piston of which is connected to a larger piston. However, this valve has no electro-hydraulic pilot control with feedback and the valve only acts as an on / off valve, without the possibility of a constant adjustment of the throttle point. The differential pistons shown in DE-B 2112 813 and DE-A 2 533 829 also lack the possibility of actuating these 2-way cartridge valves. Finally, there is no mechanical position feedback between the throttle piston and the pilot valve.

In einer besonderen Ausführungsform des erfindungsgemäßen Drosselventils sind Drosselkolben und Vorsteuerschieber parallel zueinander bewegbar, und die zwischen beiden abgestützte Feder ist ein Federstab, der entweder am Drosselkolben, an der Kolbenstange oder am Vorsteuerschieber fest eingespannt ist. Durch den Federstab wird ein häufiger Nachteil der Schraubenfedern, die Ermüdung, vermieden. Zur Druckentlastung der Kolbenstange gegenüber dem auf dem Drosselkolben lastenden, hydraulischen Druck in Verschieberichtung kann eine Druckentlastungsbohrung Drosselkolben, Kolbenstange und Differentialkolben durchdringen und in einen durch Druckentlastungskolben abgeschlossenen Gegendruckraum münden. Weiter kann erfindungsgemäß der Differentialkolben in einem gemeinsamen Differentialzylinder liegen, wobei die wirksame Flächendifferenz auf der Schließseite zum Entlastungskolben größer ist als die Flächendifferenz auf der Öffnungsseite.In a special embodiment of the throttle valve according to the invention, the throttle piston and pilot spool are movable parallel to one another, and the spring supported between the two is a spring rod which is firmly clamped either on the throttle piston, on the piston rod or on the pilot spool. The spring rod avoids a common disadvantage of the coil springs, fatigue. To relieve the pressure on the piston rod in relation to the hydraulic pressure on the throttle piston in the direction of displacement, a pressure relief bore can penetrate the throttle piston, piston rod and differential piston and open into a counterpressure chamber sealed by a pressure relief piston. Furthermore, according to the invention, the differential piston can lie in a common differential cylinder, the effective area difference on the closing side from the relief piston being greater than the area difference on the opening side.

Durch die erfindungsgemäße Lösung wird erreicht, daß die Betätigung des Drosselkolbens in beiden Richtungen allein von der Vorsteuerung abhängig ist. So wird erreicht, daß das Drosselventil auch dann sicher schließt, wenn im Fördersystem keine nennenswerte Druckdifferenzen vorhanden sind. Ein weiterer Vorteil ist darin zu sehen, daß das Drosselventil in beiden Durchflußrichtungen brauchbar und wirksam ist.The solution according to the invention ensures that the actuation of the throttle piston in both directions depends solely on the pilot control. This ensures that the throttle valve closes reliably even when there are no significant pressure differences in the conveyor system. Another advantage is the fact that the throttle valve is useful and effective in both flow directions.

Anhand der beigegebenen Zeichnungen werden drei Ausführungsbeispiele der Erfindung näher erläutert. Es zeigen:

  • Fig. 1 ein erfindungsgemäßes Proportionaldrosselventil;
  • Fig. 2 eine Modifizierung des Drosselventils nach Fig. 1; und
  • Fig. 3 ein weiteres Ausfürungsbeispiel.
Three exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings. Show it:
  • Fig. 1 an inventive Proportional throttle valve;
  • FIG. 2 shows a modification of the throttle valve according to FIG. 1; and
  • Fig. 3 shows another exemplary embodiment.

Das Proportionalventil 1 nach Fig. 1 weist einen Drosselkolben 5 auf, welcher einen Ölstrom in Durchlaufrichtung 4.1 oder 4.2 steuert. Dieser Drosselkolben ist durch Kolbenstange 6 mit dem Differentialkolben 7 fest verbunden. Der Differentialkolben gleitet in dem Differentialzylinder 23, welcher auf der Schließseite 21 durch Kolbenfläche 16 am Sperrkolben 20 und auf der Öffnungsseite 22 durch Kolbenfläche 17 am Drosselkolben 5 begrenzt wird. Am anderen Ende der Kolbenstange 6 sitzt der Druckentlastungskolben 13 in dem Gegendruckraum 15, der über einen Druckentlastungskanal 12 mit der Stirnfläche des Drosselkolbens verbunden und so groß ist, daß an der Einheit aus Drosselkolben, Kolbenstange und Druckentlastungskolben ein Ausgleich der hydraulischen, durch das Fördermedium bewirkten Kräfte in Bewegungsrichtung der Kolbenstange eintritt.The proportional valve 1 according to FIG. 1 has a throttle piston 5, which controls an oil flow in the direction of passage 4.1 or 4.2. This throttle piston is firmly connected to the differential piston 7 by piston rod 6. The differential piston slides in the differential cylinder 23, which is delimited on the closing side 21 by piston surface 16 on the locking piston 20 and on the opening side 22 by piston surface 17 on the throttle piston 5. At the other end of the piston rod 6, the pressure relief piston 13 is seated in the counterpressure chamber 15, which is connected to the end face of the throttle piston via a pressure relief duct 12 and is so large that on the unit comprising the throttle piston, piston rod and pressure relief piston the hydraulic medium caused by the medium is balanced Forces occur in the direction of movement of the piston rod.

Ein mittels eines Elektromagneten 2 bewegter Vorsteuerschieber 3 ist parallel zur Einheit aus Drosselkolben 5, Kolbenstange 6, Differentialkolben 7 und Druckentlastungskolben 13 bewegbar und nimmt - zunächst - eine dem dem Elektromagneten 2 aufgegebenen Vorsteuersignal (Strom) entsprechende Stellung ein, wodurch eine der beiden Steuerdruckleitungen 8, 9 zur Öffnungsseite 22 bzw. Schließseite 21 des Differentialzylinders 23 freigegeben wird; der Differantialkolben bewegt sich entsprechend und damit der Drosselkolben. Mit der Bewegung des Vorsteuerschiebers einerseits und der Differentialkolbeneinheit (5, 6, 7,13) andererseits biegt sich der an der Kolbenstange 6 eingespannte und in den Vorsteuerschieber 3 gelenkig eingreifende Federstab 11. Dadurch übt der Federstab auf den Vorsteuerschieber einerseits und den Drosselkolben andererseits eine Rückstellkraft aus, die zu der Magnetkraft am Vorsteuerschieber einerseits und der hydraulischen Kraft am Differentialkolben andererseits im Gleichgewicht steht. In dieser Weise wird die Drosselkolbenstellung auf die Vorsteuerung zurückgeführt. Die Stellung des Vorsteuerschiebers 3 wird entsprechend der Stellung des Drosselkolbens 5 im Verhältnis zum Vorsteuersignal korrigiert.A pilot spool 3 moved by means of an electromagnet 2 can be moved parallel to the unit comprising throttle piston 5, piston rod 6, differential piston 7 and pressure relief piston 13 and - initially - assumes a position (current) corresponding to the pilot signal (current) given to the electromagnet 2, as a result of which one of the two control pressure lines 8 , 9 to the opening side 22 or closing side 21 of the differential cylinder 23 is released; the differential piston moves accordingly and thus the throttle piston. With the movement of the pilot spool on the one hand and the differential piston unit (5, 6, 7, 13) on the other hand, the spring rod 11 clamped on the piston rod 6 and articulatedly engaging in the pilot spool 3 bends. As a result, the spring rod exerts one force on the pilot spool on the one hand and the throttle piston on the other Restoring force that is in balance with the magnetic force on the pilot spool on the one hand and the hydraulic force on the differential piston on the other. In this way, the throttle piston position is returned to the pilot control. The position of the pilot spool 3 is corrected in accordance with the position of the throttle piston 5 in relation to the pilot signal.

Von Bedeutung sind die Flächen Verhältnisse arn Differentialkolben. In Schließrichtung wirkt die Kolbenfläche 10, vermindert um die Kolbenfläche 16 am Sperrkolben 20. Diese Flächendifferenz ist größer als die in Öffnungsrichtung wirksame Fläche 14 vermindert um die Fläche 17 am Drosselkolben. In der Nullstellung der Vorsteuerung, in der Bund 24 und 25 die Ringkanäle 26 und 27 im wesentlichen abdecken, ist über Kanal 18, Verbindungskanal 19 sowie Leckagen sowohl an der Kolbenfläche 10 als auch an der Gegenfläche 14 der Vorsteuerdruck wirksam. Wegen des Flächenverhältnisses wird der Drosselkolben in Schließrichtung gedrückt. Wird zur Öffnung des Drosselkolbens 5 der Elektromagnet 2 so erregt, daß sich der Vorsteuerschieber nach unten (Zeichnung) bewegt, so wird Ringraum 26 und Kanal 8 mit dem Verbindungskanal 19 und Ringkanal 27 mit dem (hier nicht dargestellten) Abfluß zum Tank verbunden. Infolge der Druckdifferenz auf Schließ- und Öffnungsseite wird der Differentialkolben nach oben bewegt und der Durchfluß am Drosselkolben geöffnet. Diese Bewegung wird durch den Federstab 11 auf den Vorsteuerschieber 3 im Schließsinne zurückgeführt, so daß das Ventil ein proportionales Regelverhalten zeigt.The area ratios in the differential pistons are important. The piston surface 10 acts in the closing direction, reduced by the piston surface 16 on the locking piston 20. This surface difference is greater than the surface 14 effective in the opening direction, reduced by the surface 17 on the throttle piston. In the zero position of the pilot control, in which the collar 24 and 25 essentially cover the ring channels 26 and 27, the pilot pressure is effective via channel 18, connecting channel 19 and leaks both on the piston surface 10 and on the counter surface 14. Because of the area ratio, the throttle piston is pressed in the closing direction. If the electromagnet 2 is excited to open the throttle piston 5 so that the pilot spool moves downward (drawing), the annular space 26 and the channel 8 are connected to the connecting channel 19 and the annular channel 27 to the drain (not shown here) to the tank. As a result of the pressure difference on the closing and opening sides, the differential piston is moved upwards and the flow on the throttle piston is opened. This movement is returned by the spring rod 11 to the pilot spool 3 in the closing direction, so that the valve shows a proportional control behavior.

Das Ventil nach der Erfindung hat den Vorteil, daß es hydraulisch, jedoch unabhängig vom Fördermedium und dessen Druck gesteuert werden kann. Hierzu wird der Vorsteuerdruckkanal 18 mit einer geeigneten Druckquelle verbunden, die einen genügend hohen Druck liefert. Dadurch ist ein sicheres Öffnen und Schließen mit hohen Geschwindigkeiten möglich, auch wenn von dem Drosselventil ein Medium mit sehr geringem Druck gesteuert wird.The valve according to the invention has the advantage that it can be controlled hydraulically, but independently of the medium and its pressure. For this purpose, the pilot pressure channel 18 is connected to a suitable pressure source that delivers a sufficiently high pressure. This enables safe opening and closing at high speeds, even if the throttle valve controls a medium with very low pressure.

Bei ausreichendem Systemdruck auf beiden Seiten des Drosselventils kann der Vorsteuerdruckkanal (18) jedoch auch mit einer der Leitungen verbunden werden, zwischen welchen der Drosselkolben den Durchfluß steuert. Erwähnenswert ist, daß auch relativ geringe Systemdrücke ausreichen, da Schließgeschwindigkeit und Schließkraft auch durch die Vorgabe des Flächenverhältnisses an dem Differentialkolben beeinflußt werden können.If the system pressure on both sides of the throttle valve is sufficient, the pilot pressure channel (18) can also be connected to one of the lines between which the throttle piston controls the flow. It is worth mentioning that even relatively low system pressures are sufficient, since the closing speed and closing force can also be influenced by specifying the area ratio on the differential piston.

Das Ventil hat den weiteren Vorteil, daß es in beiden Richtungen (Pfeile 4.1 und 4.2) durchströmt werden kann.The valve has the further advantage that it can be flowed through in both directions (arrows 4.1 and 4.2).

Fig. 2 zeigt eine Modifizierung des Drosselventils nach Fig. 1, mit demselben Aufbau und denselben Eigenschaften. Insbesondere kann das Drosselventil in den beiden Stromrichtungen, (Pfeil 4.1 und 4.2) durchströmt werden. Durch besondere Maßnahmen wird zusätzlich erreicht, daß die Schaltgeschwindigkeit und die leckfreie Dichtung des Drosselkolbens sowohl bei sehr geringen Druckdifferenzen zwischen Zu- und Ablauf (d.h. insbesondere bei großen Durchflußmengen), als auch bei Druckabfall in einer der Leitungen 28, 29 gewährleistet bleiben.FIG. 2 shows a modification of the throttle valve according to FIG. 1, with the same structure and the same properties. In particular, the throttle valve can be flowed through in the two flow directions (arrow 4.1 and 4.2). Special measures also ensure that the switching speed and the leak-free seal of the throttle piston are guaranteed both with very small pressure differences between the inlet and outlet (i.e. especially with large flow rates) and with pressure drop in one of the lines 28, 29.

Ergänzend zu Fig. 1 ist in Fig. 2 dargestellt, daß der Magnet 2 einen Stößel 30 besitzt, der auf den Vorsteuerschieber 3 einwirkt. Dargestellt ist ferner der Tankkanal 31, welcher durch die Tankbrücke 32 den Vorsteuerzylinder an seinen beiden Enden drucklos macht. Die hier dargestellte Ergänzung veranschaulicht, daß das Vorsteuerventil als hydraulische Brücke (Wheatstonesche Meßbrücke) wirkt, durch welche in den Vorsteuerkanälen 8 und 9 unterschiedliche Steuerdrücke erzeugt werden zur Betätigung des Differentialkolbens 7. Im Unterschied zu dem Ausführungsbeispiel nach Fig. 1 wirkt auf den Drosselkolben 5 des Ventils nach Fig. 2 die im Gegendruckraum 15 untergebrachte Feder 33 in Schließrichtung. Hiermit wird folgendes erreicht: Es mag wünschenswert sein, die Schließseite 21 des Differentialkolbens ständig mit einem geringen Druck zu belasten. Aus diesem Grunde werden Magnet 2 und Vorsteuerschieber 3 so eingestellt, daß am Kolbenbund 25 ständig und auch in der Nullstellung des Vorsteuerventils bzw. Schließstellung des Drosselkolbens 5 ein geringer - hier nicht darstellbarer - Spalt besteht, durch den ein geringer Ölstrom aus Verbindungskanal 19 auf die Schließseite des Differentialkolbens 7 gelangt. Dieser geringe Spalt bedeutet in Fig. 2 eine geringe Verschiebung des Vorsteuerschiebers 3 nach oben und damit auch eine entsprechende geringe Auslenkung der Feder 11, verbunden mit einer nach oben gerichteten geringen Federkraft. Die Feder 32 dient nun dem Zweck, diese Federkraft, die unerwünschter Weise im Öffnungssinne des Drosselkolbens 5, wirkt, zu kompensieren.In addition to Fig. 1, it is shown in Fig. 2 that the magnet 2 has a plunger 30 which acts on the pilot valve 3. Also shown is the tank channel 31 which, through the tank bridge 32, depressurises the pilot cylinder at both ends. The addition shown here illustrates that the pilot valve acts as a hydraulic bridge (Wheatstone measuring bridge), by means of which different control pressures are generated in the pilot channels 8 and 9 for actuating the differential piston 7. In contrast to the exemplary embodiment according to FIG. 1, this acts on the throttle piston 5 2 in Counter pressure chamber 15 accommodated spring 33 in the closing direction. This achieves the following: It may be desirable to constantly load the closing side 21 of the differential piston with a low pressure. For this reason, the magnet 2 and pilot spool 3 are set so that there is a small - not representable - gap on the piston collar 25 constantly and also in the zero position of the pilot valve or closed position of the throttle piston 5, through which a small oil flow from the connecting channel 19 to the Closing side of the differential piston 7 arrives. In FIG. 2, this small gap means a slight displacement of the pilot spool 3 upwards and thus also a correspondingly small deflection of the spring 11, combined with an upwardly directed small spring force. The spring 32 now serves the purpose of compensating for this spring force, which acts undesirably in the opening direction of the throttle piston 5.

In Fig. 2 ist ferner dargestellt, daß der Vorsteuerdruckkanal 18 wechselweise mit dem Druck der Leitungen 28 oder 29 beaufschlagt wird. Hierzu ist ein Wechselventil 34 vorgesehen. Dessen Eingänge sind mit der Leitung 29 andererseits verbunden. Der Mittelausgang 35 des Wechselventils 34 führt in den Vorsteuerdruckkanal 18.In Fig. 2 it is also shown that the pilot pressure channel 18 is alternately acted upon by the pressure of the lines 28 or 29. For this purpose, a shuttle valve 34 is provided. Its inputs are connected to line 29 on the other hand. The central outlet 35 of the shuttle valve 34 leads into the pilot pressure channel 18.

Das Wechselventil 34 bewirkt, daß im Vorsteuerdruckkanal 18 jeweils der höhere Druck der Leitungen 28 oder 29 anliegt. Bei Druckgleichheit sind beide Drücke der Leitungen 28, 29 gleichermaßen wirksam. Bei Änderung der Stromrichtungen (Pfeile 4.1, 4.2) erfolgt automatisch eine Umschaltung des Steuerdrucks. Das Vorsteuerventil wird auch dann mit dem erforderlichen Drucköl versorgt, wenn eine der Leitungen 28 oder 29 drucklos geschaltet wird, z.B. indem sie mit dem Tank verbunden wird. Anstelle des Wechselventils kann jedes andere druckabhängig schaltbare Ventil verwandt werden. Das Wechselventil zeichnet sich jedoch durch robuste und einfache Bauweise aus.The shuttle valve 34 causes the higher pressure of the lines 28 or 29 to be present in the pilot pressure channel 18. If the pressure is equal, both pressures of the lines 28, 29 are equally effective. When changing the current directions (arrows 4.1, 4.2), the control pressure is automatically switched. The pilot valve is also supplied with the required pressure oil when one of the lines 28 or 29 is depressurized, e.g. by connecting it to the tank. Instead of the shuttle valve, any other pressure-dependent switchable valve can be used. However, the shuttle valve is characterized by its robust and simple construction.

Fig. 3 zeigt ein Ausführungsbeispiel, bei dem nur eine Stromrichtung (Pfeil 4.1) möglich ist. Der Steuerdruck wird stets der Leitung 29 über den zentralen Druckentlastungskanal 12 entnommen. Der Vorteil der Ventile nach den Figuren 1 und 2 bleibt jedoch auch hier erhalten:Fig. 3 shows an embodiment in which only one current direction (arrow 4.1) is possible. The control pressure is always taken from line 29 via the central pressure relief channel 12. However, the advantage of the valves according to FIGS. 1 and 2 is also retained here:

Auch dieses Ventil ist unabhängig von der Druckdifferenz zwischen den Leitungen 29 und 28. Die Schließkraft und Schließgeschwindigkeit hängt ebenfalls von den Flächenverhältnissen am Differentialkolben 7 ab, so daß auch niedrige Systemdrücke zur Vorsteuerung ausreichen. Die Sitzkraft kann noch dadurch gefördert werden, daß die Schließseite des Differentialkolben 7 auch in der Nullstellung des Drosselkolbens bzw. Vorsteuerventils mit einem Druck beaufschlagt wird. Dies kann - wie in Fig. 2 beschrieben - dadurch geschehen, daß Magnet 2 und Vorsteuerschieber 3 wiederum so eingestellt werden, daß in der Nullstellung des Vorsteuerschiebers 3 am Kolbenbund 25 ein geringer Spalt zur Verbindung der Steuerdruckleitung 9 mit dem Verbindungskanal 19 geöffnet ist. Im Ausführungsbeispiel nach Fig. 3 ist für die hierzu erforderliche geringe Verschiebung des Vorste).'°''schiebers 3 eine verhältnismäßig schwache Druckfeder 36 vorgesehen. Im übrigen erfolgt das Schließen des Drosselventils nach Fig. 1 bis 3 dadurch, daß der Strom und dementsprechend die auf das Vorsteuerventil wirkende Ventilkraft des Elektromagneten verringert oder abgeschaltet wird. Die von dem Federstab 11 ausgeübte Kraft bringt nun das Vorsteuerventil in eine Position, in der Kolbenbund 25 den Verbindungakanal 19 mit Vorsteuerkanal 9 verbindet. Damit wird der Differentialkolben 7 im Sinne des Schließens mit Drucköl beaufschlagt.This valve is also independent of the pressure difference between lines 29 and 28. The closing force and closing speed also depend on the surface conditions on the differential piston 7, so that even low system pressures are sufficient for pilot control. The seating force can also be promoted in that the closing side of the differential piston 7 is pressurized even when the throttle piston or pilot valve is in the zero position. This can - as described in Fig. 2 - happen that magnet 2 and pilot spool 3 are in turn adjusted so that in the zero position of the pilot spool 3 on the piston collar 25 a small gap for connecting the control pressure line 9 to the connecting channel 19 is opened. In the exemplary embodiment according to FIG. 3, a relatively weak compression spring 36 is provided for the slight displacement of the fore). Otherwise, the throttle valve according to FIGS. 1 to 3 is closed in that the current and accordingly the valve force of the electromagnet acting on the pilot valve is reduced or switched off. The force exerted by the spring rod 11 now brings the pilot valve into a position in which the piston collar 25 connects the connecting channel 19 to the pilot channel 9. So that the differential piston 7 is acted upon in the sense of closing with pressure oil.

Der Druckentlastungskanal muß nicht in der Kolbenstange liegen. Er kann sich auch parallel dazu in dem Gehänge von dem Kanal 29 in den Gegendruckraum 15 erstrecken, damit die beiden gleich großen wirksamen Kolbenflächen an den Enden der Kolbenstange, das heißt Stirnseite des Drosselkolbens 5 und wirksame Kolbenfläche des Druckentlastungskolbens 15 (Fig. 1; Fig. 2) bzw. des Sperrkolbens 20 (Fig. 3) druckausgeglichen sind.The pressure relief channel does not have to be in the piston rod. It can also extend parallel to it in the hanger from the channel 29 into the counter-pressure chamber 15, so that the two equally effective piston surfaces at the ends of the piston rod, i.e. the end face of the throttle piston 5 and the effective piston surface of the pressure relief piston 15 (Fig. 1; Fig . 2) or the locking piston 20 (Fig. 3) are pressure balanced.

Claims (7)

1. Electro-hydraulic pilot-operated proportional throttle valve (1)
comprising an electro-magnetically actuated pilot valve (2, 3),
a main valve (1) with a choke piston (5) which is mechanically connected to a double-acting control piston (7),
and a mechanical position feedback means (11) arranged between the choke piston (5) and the pilot valve spool (3),
characterized by the fact
that one face of the choke piston (5) is impinged by the hydraulic fluid,
that the control piston is designed as a differential piston (7) having a diameter greater than that of the choke piston (5) and is connected to the second face (17) of the choke piston and slidable in a differential cylinder (23),
that the control pressure chamber (22) of the differential cylinder (23), which is associated to the annular surface (14) surrounding the piston rod of the differential piston (7) and arranged on the opening side of the differential cylinder (23), is bordered by the second face (17) of the choke piston (5),
that the control pressure chamber (21) of the differential cylinder (23), which is associated to the piston surface (10) of the differential piston (7) and arranged on the closing side of the differential cylinder (23), is bordered by a blocking piston/relief piston means (20, 13) which is connected with the differential piston (7) and the diameter of which is identical with that of the choke piston (5), and that the face of the blocking piston/relief piston means (20, 13) opposite from the differential piston (7) is impinged by the same operating pressure as is the first face of the choke piston (5).
2. Device according to claim 1,
characterized by the fact
that the mechanical position feedback means (11) is a spring which is supported between the choke piston (5) and the pilot valve spool (3).
3. Device according to claim 2,
characterized by the fact
that the choke piston (5) and the pilot valve spool (3) are movable parallelly to each other and that the spring is designed as a resilient bar (11) which at its one end is fixedly secured to the piston rod (6) and at its other end is pivoted to the pilot valve spool (3).
4. Device according to any one of claims 1 to 3,
characterized by the fact
that a pressure relief duct (12) extends through choke piston (5), piston rod,(6), differential piston (7), and blocking piston/relief piston means (20, 13) and opens into a back pressure chamber (15) which is closed by the blocking piston/relief piston means (20, 13) on the side facing to the choke piston (5).
5. Device according to any one of claims 1 to 3,
characterized by the fact
that a pressure relief piston (13) and a blocking piston (20) are positioned at an axial distance on the piston rod (6),
with the blocking piston (20) bordering on the closing side (21) of the differential cylinder (23), and the pressure relief piston (13) closing a back pressure chamber (15) at the end side of the piston rod, which chamber (15) is connected (pressure relief duct 12) to the hydraulic fluid line (29) opening coaxially to the piston rod (6) into the valve (1),
and that the cylinder chamber between the blocking piston (20) and the pressure relief piston (13) communicates with the pressurized side of the hydraulic side (29 or 28), on the one hand, and with the pilot valve via connecting line (19), on the other hand.
6. Device according to claim 5,
characterized by the fact
that the cylinder chamber between the blocking piston (20) and the pressure relief piston (13) communicates via a shuttle valve (34) with the lines (28, 29) for supplying and discharging the hydraulic fluid, the inlets of the shuttle valve (34) being connected to the lines (28, 29) and the centre outlet (35) of the shuttle valve being connected to the inlet of the pilot valve.
7. Device according to any one of claims 1 to 6,
characterized by the fact
that the piston rod (6) is impinged in the closing direction by a compensating spring (33).
EP82108826A 1981-09-26 1982-09-24 Electro-hydraulic pilot-operated proportional throttle valve Expired EP0083688B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3138345 1981-09-26
DE3138345 1981-09-26

Publications (3)

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EP0083688A2 EP0083688A2 (en) 1983-07-20
EP0083688A3 EP0083688A3 (en) 1984-03-28
EP0083688B1 true EP0083688B1 (en) 1986-08-13

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Country Status (3)

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EP (1) EP0083688B1 (en)
DE (1) DE3272593D1 (en)

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Also Published As

Publication number Publication date
US4535966A (en) 1985-08-20
DE3272593D1 (en) 1986-09-18
EP0083688A2 (en) 1983-07-20
EP0083688A3 (en) 1984-03-28

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