EP1781953A1

EP1781953A1 - Pilot valve, especially for servo valves

Info

Publication number: EP1781953A1
Application number: EP05781992A
Authority: EP
Inventors: Johannes Rauch; Matthias Rustler
Original assignee: Bosch Rexroth AG
Current assignee: Bosch Rexroth AG
Priority date: 2004-08-06
Filing date: 2005-08-02
Publication date: 2007-05-09
Anticipated expiration: 2025-08-02
Also published as: CN101010519B; DE102004038380B4; US7631663B2; EP1781953B1; CN101010519A; US20070215222A1; WO2006015771A1; DE102004038380A1

Abstract

Disclosed is a pilot valve, especially for a servo valve, comprising an actuating motor (6) and a hydraulic preamplifier via which a control pressure difference can be created that acts upon a main slider (32) of a main stage (4). According to the invention, a blocking mechanism (26) is embodied in the flow path of the control oil. A control duct (14, 16) that is connected, either directly or via a branch, to a control chamber of the main stage can be blocked by manually actuating said blocking mechanism (26) while the other control duct remains open. The other control duct can be blocked by actuating the blocking mechanism in the opposite direction while the first control duct remains open. A control pressure difference by means of which the main slider can be displaced into a predetermined position can be created manually by actuating said blocking mechanism.

Description

description

Pilot valve, especially for servo valves

The invention relates to a pilot valve, in particular for servo valves, according to the preamble of patent. Statement 1.

For electro-hydraulic servo valves, the hydraulic output (fluid flow or pressure) is proportional to the electrical input signal. For larger pressure medium flow rates, two-stage servo valves are usually used, in which a main stage is adjusted via a hydraulic pilot control stage. Such a two-stage servo valve, for example, sold under the product name 4WS.2DM by the applicant. The pilot stage essentially consists of a control motor, via which the position of a baffle plate can be changed between two control nozzles. By approaching the baffle plate to one of the control nozzles, a control oil flow is reduced by this, while 'increases the control oil flow through the other control nozzle. In the control oil flow path to each nozzle, an orifice is arranged in each case, so that the change in the control oil volume flow correspondingly also reduces or increases the pressure drop across the respective orifices.

The downstream of the diaphragm adjusting pressure is tapped in each case via a control channel and guided to a main spool of a main stage frontally beauf¬ striking control surfaces, so that it is moved in response to the resulting pressure difference in a control position. The baffle plate and the control nozzles thus act as a hydraulic amplifier, via which the due to the control of the servomotor caused shift in position in a pressure difference is umge¬ sets.

In some applications, it is necessary, for example, for commissioning of the system in an accident (emergency stop) or troubleshooting to bring the servo pilot valve by hand in a predetermined position so that the main spool adjusted accordingly and the system depressurized or like that becomes.

The company Moog Servoverstellgeräte under the name D062-900 are offered in which the mecha¬ African emergency operation is carried out by a lever which is arranged on a servomotor encompassing the cap of the servo valve and engages directly on the servo motor.

The disadvantage of this solution is that when the lever is forcibly actuated, the servomotor can be damaged and that the lever mimic is also relatively sensitive to contamination and vibrations of the system.

In contrast, the invention has the object zugrun¬ de, a pilot valve, in particular for a servo valve to create, which allows a reliable manual operation with a simple structure.

This object is achieved by a pilot valve having the features of patent claim 1.

According to the invention, the pilot valve is designed with a manually operable locking device, via which at least one of those nozzle channels can be controlled, via which control oil is led to regulating nozzles, between which a baffle plate or the like of the pilot valve is arranged. By operating this locking device, the control oil volume flow to a control nozzle out shut off and thus generates a pressure drop over which the directional control valve is brought into its desired position, which should be taken in case of "emergency stop" or for maintenance.

Such an integrated in a hydraulic preamplifier of the pilot valve actuator does not require direct access to the servo motor, so that this sensitive component is protected against damage. Furthermore, such a locking device can be integrated with minimal device complexity in the servo valve, so that this very compact, without protruding components, such as the lever in the prior art - is executable.

In a particularly preferred embodiment, the locking device has a double-acting piston, the actuation of which leading to a control nozzle nozzle duct is zuusteuerbar, while the leading to the other control nozzle nozzle channel remains open. That is, depending on the direction of actuation, the control oil volume flow to the one control nozzle or the other control nozzle can be interrupted to adjust the main stage either in one direction or in the other direction.

It is particularly preferred if the piston is designed as a rotary piston which is rotatably arranged in a housing of the pilot valve.

The piston is preferably embodied on its outer circumference with two recesses which, in a piston basic position, release a nozzle channel flow cross section and, in a blocked position of the rotary piston, control the cross section of a nozzle channel through a control edge bounded by the recess, while the flow cross section the other nozzle channel substantially remains unchanged. When the piston is rotated in the opposite direction, the other nozzle channel is then closed and the first-mentioned nozzle channel remains in its open position.

The servo valve is particularly compact, when the piston and the piston bore receiving this form part of the control oil flow path, so that complicated additional channel bores can be dispensed with.

The piston is preferably biased via one or more return springs in its basic position in which both control oil cross sections are opened. In a particularly preferred embodiment, a spring-biased return plunger dips into a radial recess of the rotary piston so that it can be rotated against the force of the return spring and, when released, is rotated back into its basic position.

The pilot valve according to the invention is preferably equipped with an electrical return of the baffle plate, which ensures that the baffle plate is returned to a predetermined position between the control nozzles when the predetermined control position is reached.

The housing of the pilot valve can be made particularly compact, when the piston and the control nozzle forming nozzle body are axially parallel angeord¬ net.

Other advantageous developments of the invention are the subject of further subclaims. In the following, a preferred embodiment of the invention is explained in more detail with reference to schematic drawings. Show it:

Figure 1 is a schematic diagram of a servo valve with a servo pilot valve according to the invention;

FIG. 2 shows a three-dimensional representation of a concrete embodiment of a servo-pilot valve;

FIG. 3 is a sectional front view of the servo valve of FIG. 2;

FIG. 4 shows a sectional side view of the servo valve of FIG. 2;

FIG. 5 is a sectional plan view of the servo valve of FIG. 2;

FIG. 6 shows a three-dimensional representation of a rotary piston of the servo valve from FIG. 2.

Figure 1 shows the schematic basic structure of a two-stage servo valve I ₇ which consists essentially of a pilot stage 2 and a main stage 4.

The pilot stage has a servomotor 6, via which a baffle plate 8 of a hydraulic preamplifier can be pivoted. The baffle plate 8 is arranged between two control nozzles 10, 12 which are each connected via a nozzle channel 14 and 16 to a pressure port P 'of the pilot stage 2. This pressure port P ¹ is connected to a pressure line 18, which is supplied via a pump 20 with pressure medium. In each of the two nozzle channels 14, 16, an input aperture 22, 24 is provided, to which a blocking device 26 is assigned. This is designed such that it is arranged in its illustrated basic position in a passage position in which the nozzle channels 14, 16 can be flowed through by the Steuerδl branched off from the pressure line 18. By manual operation of the locking device 26 can be either the nozzle channel 14 or the nozzle channel 16th shut off, the other nozzle channel 16 or 14 remains open. That is, depending on the direction of actuation one of the nozzle channels 14, 16 is shut off, the other can be flowed through by the control oil.

From the two nozzle channels 14, 16 branches off ei¬ ne control line 28 and 30, which leads to terminals, A ¹ and B 'of the pilot stage 2 and from there to the Steuer¬ spaces of a valve spool 32 of the main stage 4. The valve spool 32 is thus displaced as a function of the control pressure difference in the two control lines 28, 30 in a control position.

The control oil flows in the basic position of the Sperr¬ device 26 from the pressure port P 'of the pilot stage 2 via the two nozzle channels 14, 16 and the controlled locking device 26 to the two control nozzles 10, 12 and from there against the baffle plate 8 and back into the tank T. As long as the baffle plate 8 is in its middle position, the control oil volume flow through the two control nozzles 10, 12 and correspondingly the pressure drop across the two input panels 22, 24 is equal, so that in each case the same control pressure is applied to the control chambers of the valve spool 32 of the main stage 4 - The valve slide 32 remains in its basic position.

To set the control position of the servo motor 6 is controlled by a controller, not shown, so that the baffle plate 8 is pivoted and one of the control nozzles 10, 12 approaches. As a result, the control oil volume flow via the respective nozzle-for example, the control nozzle 10 -is reduced, so that the pressure difference across the associated control panel 22 is reduced. At the same time, the control oil volume flow increases via the other control nozzle 12, so that the pressure drop above the associated inlet nozzle 24 increases - the over the Control channels 28, 30 tapped control pressure difference changes, so that the valve spool 32 is moved to a corresponding control position. By an electrical feedback, the resulting axial displacement of the valve spool 32 is detected and upon reaching the predetermined setpoint, the baffle plate by suitable control of the servo motor 6 in its center position process back, so that the Ventilschie¬ ber 32 remains in the desired control position.

The manually operable locking device 26 makes it possible, in an emergency or for maintenance purposes, to actuate the blocking device 26 in such a way that one of the nozzle channels 14, 16 is shut off, so that a control pressure difference is generated which produces the valve slide 32 shifts to a predetermined end position. The baffle plate 8 does not remain in its middle position, since it is only flowed on one side and accordingly pivots in Rich¬ direction of the shut-off control nozzle 12 (with non-actuated servomotor S). Accordingly, the control oil volume flow via the other control nozzle 10 and thus also the pressure drop across the associated inlet panel 22 increases, so that the effective on the valve spool 32 pressure difference is slightly reduced - but this is still moved to the predetermined end position for maintenance or intended for emergency shutdown.

Figures 2 to 6 show details of a concrete embodiment of a pilot stage 2 as it is applicable to a servo valve 1 according to FIG. FIG. 2 shows a three-dimensional view of this specific exemplary embodiment of a pilot control stage 2. This has an approximately cuboidal housing 34 onto which the positioning motor 6 - for example a torque motor is screwed via a mounting flange 34. As is apparent in particular from the sectional side view according to FIG. is, the torque motor 6 is surrounded by a motor housing 38, on which the power supply and the Signalan¬ circuits 40 are formed. The mounting flange 36 immersed in accordance with Figure 3 with a hub-shaped projection in a baffle plate 42 a. Through this hub-shaped projection, the baffle plate 8, which is attached to an armature 44 of the servomotor 6 extends. The mounting flange 36 with the hub-shaped projection forms an elastic spring tube, which allows a deflection of the baffle plate 8 transversely to the plane in Figure 3. The lower end section of the baffle plate 8 in FIG. 3 penetrates through the hub-shaped projection of the fastening flange 36 into a baffle hole 46 designed as a blind hole. In a nozzle bore 46 arranged transversely thereto, two nozzle bodies 48 are exchangeably received. These nozzle bodies 48 are pretensioned by fastening screws 50 against a respective radial shoulder of the nozzle bore 56. At each of the baffle plate 8 associated end portion of the nozzle body 48, 50 is one of the control nozzles 10, 12 ausge¬ forms.

These control nozzles 10, 12 are connected to the pressure connection P 'by control channels which are described in greater detail below, which surface is formed on the large surface of the housing 34 remote from the positioning motor 6. The sealed end portion of the baffle plate bore 42 is connected via a in the sectional side view of Figure 4 and also in Figure 2 indicated tank passage 56 and a sealed transverse bore 58 to the tank port T. In the representation according to FIG. 2, the transverse bore 58 is indicated by dashed lines only, and the closure plug 54, which is inserted into this transverse bore 58, is visible.

According to FIGS. 2 and 3, a peripheral groove 60, 62 is formed on the outer circumference of the nozzle bodies 48, 50. det, in the transverse bores 64, 66 of a nozzle bore 68, 70 of the nozzle body 48 and 50 open. The annular spaces formed by the circumferential grooves 60, 62 and the peripheral wall of the transverse bore 58 are connected via the nozzle channels 14, 16, which are merely indicated in FIGS. 2 and 3, to a piston bore 72, in which a rotary piston 74 is rotatably mounted. The piston bore 72 is designed as a blind bore and the left end section of the rotary piston 74 in FIG. 3 and FIG. 5 terminates with the left end wall of the housing 34. In or at this end portion, a hexagon socket 76 or a handle is formed, via which the rotary piston 74 is verdreh¬ by hand bar. The section AA shown in Figure 3 extends according to the section line of Figure 4 graded - accordingly, the rotary piston 74 laterally offset (Figure 4) to the two coaxially arranged nozzle bodies 48, 50 angeord¬ net.

Figure 5 shows a section along the line DD in Figure 3. The rotary piston 74 per se is shown dreidi¬ dimensionally in Figure 6. Accordingly, the rotary piston 74 has two axially relatively elongated annular grooves 78, 80 and relatively narrow, but deeper grooves 82, 84, one of which is disposed to the left of the annular groove 78 and the other between the two annular grooves 78, 80. In these grooves 82, 84 3 and 5 sealing rings 85, 87 are used according to Figures. Between the annular groove 78 and the groove 84 on the one hand and the annular groove 80 and the groove 82 on the other hand, two flats 86, 88 are formed on the outer circumference of the rotary piston 74, which are offset by 75 ° to one another in the illustrated embodiment. These flats 86, 88 are slightly deeper in the radial direction than the annular grooves 78, 80 and extend in the axial direction into the respectively adjacent one. However, between the flats 86, 88 and the groove 84 remains a sealing web stand, so that no hydraulic connection to the middle groove 84 is. At the two end portions of the rotary piston 74, in each case annular collars 90, 92 rest against the inner circumferential wall of the piston bore 72.

The two flats 86, 88 of the rotary piston 74 each form a control edge 110, 112, wherein by a rotation of the rotary piston 74 in the direction of arrow R, the control edge 110 of the flattening 86 the connecting space 102 is heading, while in a rotation in the opposite direction, the control edge 112 of the flattening 88th closes the connection space 104. This rotation takes place against the return torque, which is transmitted from the spring-biased return bolt 96 to the rotary piston 74. The spring path of the return bolt 96 and the force of the spring 98 are selected so that the rotary piston 74 can only be rotated by a predetermined angle in the direction of rotation R or in the opposite direction. This Drehwin¬ angle is chosen so that it is certainly prevented that both connection spaces 102, 104 are shut off. The return bolt 96 also serves as axial securing for the rotary piston 74.

In the region of the annular groove 80, a radial groove 94 is formed aus¬ extending from the outer periphery of the rotary piston 74 to the axis, so that the radial groove 94 is bounded by a flat base whose width is equal to the diameter of the stepped back through the annular groove 80 piston ridge , The side walls are halb¬ circular, the height corresponds to the radius of this piston land. Of course, other dimensions can be selected.

As can be seen in particular from Figures 2 and 5, immersed in this radial groove 94, a return bolt 96, which via a spring 98 in its engaged position in the Radialnut 94 is biased. The spring 98 is supported at the back on a closure screw 100 screwed into the housing 34. The return pin 96 has a circular cross section whose diameter corresponds to the axial length of the radial groove 94. By means of the return bolt -96, the rotary piston 74 is biased into its basic position shown in FIGS. 2 to 6, in which the two flats 86, 88 together with the piston bore 72 each form a connecting space 102, 104 (see FIGS. 2, 3) , which are each connected via two nozzle channel bore portions 106, 108 (see Figures 2 and 5) to the pressure port P '.

According to FIG. 2, the annular spaces delimited by the two annular grooves 78, 80 and the piston bore 72 are connected to the ports A ¹ and B ^{1 of} the pilot control passage 2 via the bores (see FIG. 2) forming the control channels 28, 30.

In normal operation, i. then when the rotary piston

74 is not unscrewed from its basic position shown in FIGS. 2 to 5, the control oil is tapped off via the pressure port P ¹ and via the two nozzle channel bore sections 106, 108 and the opened connection chambers 102, 104 into the annular grooves 78, 80 limited annulus led. In this case, the nozzle channel bore sections 106, 108 form the input diaphragms 22, 24 according to FIG. From the said annular spaces, the control oil flows in each case via the nozzle bores 14, 16 formed as housing bores (see

3) into the annular spaces formed by the circumferential grooves 60, 62 of the nozzle bore 46 and from there via the transverse bores 64, 66 to the control nozzles 10, 12. The control oil then emerges from these two nozzles 10, 12 which are opposite one another. from, hits both sides of the baffle plate 8 and then flows over the baffle plate bore 42, the Transverse bore 54 (Figure 4) and the tank channel 56 to the tank port T and from there back into the tank. Since the control oil flow is the same in both control oil flow paths, the same control pressure is thus also present in the control chambers of the main stage 4 in the two control lines 28, 30 - the valve spool 32 remains in its basic position.

The setting of the control position then takes place in accordance with the comments on FIG. 1.

In the event of an emergency stop, for maintenance purposes or when starting up the system, the rotary piston 74 is rotated, for example, in the direction of arrow R (FIG. 6), so that the control edge 110 controls the associated connection space 102, so that the control oil flow path from the nozzle channel bore section 106 to the control nozzle 10 is interrupted. Accordingly, a control pressure difference at the ports A ¹ and B ', which shifts the valve spool 32 in a predetermined emergency stop or maintenance position. In this case, depending on the direction of rotation of the rotary piston 72, two different positions can be approached.

The use of the pilot stage 2 according to the invention is not limited to servo valves, in principle this pilot stage could also be used in other applications, for example in the case of pilot operated valves or the like. In principle, the solution according to the invention with the blocking device for shutting off a control channel could also be installed in an intermediate plate between a pilot stage and a main stage, so that the associated valve can be actuated by hand. In this way could possibly account for an emergency operation on the magnet of the pilot valve. The Applicant reserves the right to shut off a control channel by a locking device of a pilot stage to make its own independent claim (without baffle plate, etc.). Instead of the electrical feedback, a mechanical or barometric feedback of the baffle plate 8 may be provided.

Disclosed is a pilot valve, in particular for a servo valve, with a servomotor and a hydraulic preamplifier. This can be used to generate a control pressure difference, which depends on a main valve

Main stage works. According to the invention, a blocking device is formed in the control oil flow path, by means of the manual actuation of which a control channel connected directly or via a branch to a control chamber of the main stage can be shut off, the other control channel remaining open. By actuating the locking device in the direction Gegen¬ the other control channel can be shut off, in which case the first-mentioned control channel remains open. By operating this locking device can be manually generate a control pressure difference over which the main spool is displaced to a predetermined position.

LIST OF REFERENCE NUMBERS

1 servo valve

2 pilot stage

4 main level

6 servomotor

8 baffle plate

10 control nozzle

12 control nozzle

14 nozzle channel

16 nozzle channel

18 pressure line

20 pump

22 input panel

24 input panel

26 locking device

28 control channel

30 control channel

32 valve spool

34 housing

36 mounting flange

38 motor housing

40 connection

42 baffle hole

44 anchors

46 nozzle bore

48 nozzle body

50 nozzle body

52 fixing screws

54 sealing plugs

56 tank channel

58 cross bore

60 circumferential groove

62 circumferential groove

64 cross bore cross hole

nozzle bore

piston bore

rotary pistons

Allen

ring groove

groove

seal

flattening

seal

flattening

collar

radial groove

Reset hole

feather

Screw

communication space

Verbindungsrautn

Nozzle channel bore section

control edge

Claims

claims

1. pilot valve, in particular for a servo valve, with a servomotor (6) and a hydraulic Vorverstär¬ ker, the angeord¬ between two control nozzles (10, 12), from the servo motor (6) movable baffle plate (8), wherein a Control oil volume flow, which is guided in each case via a nozzle channel (14, 16) and an inlet panel (22, 24) to the control nozzles (10, 12), by changing the distance of the baffle plate (8) to the control nozzle (10, 12) is variable, and wherein the two nozzle channels (14, 16) branch off from a pressure connection (P ¹ ) leading to a supply pressure of a main stage and downstream of the input orifices (22, 24) a respective control channel (28, 30) branches off from the nozzle channels (14, 16) ) is connected to a respective control terminal A ¹ , B ¹ , to the control rooms of a main stage (4) can be connected, and with a manual over which a Steuerdruck- difference regardless of the control of the servo motor 6 to the control terminals A ¹ , B 'can be applied, gekenn¬ characterized by a manually operated locking device (26) via which one of the nozzle channels (14, 16) is zusteuerbar.

2. pilot valve according to claim 1, wherein the Sperr¬ device has a piston (74), upon actuation of a nozzle channel (14, 16) steered and the other Düsen¬ channel (16, 14) remains open.

3. pilot valve according to claim 2, wherein the piston is a rotary piston (74).

4. pilot valve according to claim 2 or 3, wherein the piston (74) on its outer circumference two recesses (86,

88), which in a piston base position has a nozzle In a blocking position of the piston (74), the flow cross-section of a nozzle channel (14, 16) can be controlled by a control edge (110, 112) bounded by a recess (86, 88), while the control oil flow cross-section of the other

Nozzle channels (16, 14) remains substantially unchanged.

5. pilot valve according to claim 4, wherein the Ausneh¬ ments flats (86, 88) which open unilaterally in annular spaces, each of an annular groove (78, 80) of the piston (74) are limited.

6. pilot valve according to one of the claims 3 to 5, wherein the rotary piston (74) has a radial groove (94) into which a spring-biased return bolt (96) is immersed.

7. pilot valve according to claim 6, wherein the Radial¬ groove (94) extends in the radial direction to the axis of the Dreh¬ piston (74).

8. pilot valve according to one of the preceding patent claims, wherein the baffle plate (8) has an electrical return.

9. Pilot valve according to one of the claims 2 to 8, wherein the nozzle body (48, 50) of the control nozzles (10, 12) and the piston (74) are arranged parallel to each other