DE2723935A1 - DEVICE FOR INDICATING THE POSITION OF A HYDRAULIC ACTUATOR - Google Patents

Description

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WPL-ING. R. BFH / JFH. ■ I) Tl. ING. K. LAMPHiCi "" D ~

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Carl OrIa Hansen, 4700 Nastved, Denmark

Device for displaying the position of a hydraulic servomotor

The invention relates to a device for displaying the position of a hydraulic servomotor of the type that Pressure oil is supplied through at least one pressure oil line and the additional one common to several servomotors Low pressure oil line is connected, which is connected to the housing of the servomotor, in order to be in this one maintain a certain oil pressure.

In hydraulic control systems in which hydraulic servomotors are operated from a control panel through pipelines are operated, feedback from each servomotor to the control panel is often required, which shows the working status of the Servomotor, i.e. the current position of the movable element of the servomotor.

Such feedback can be provided in many ways, e.g. electrically with the help of microswitches or potentiometers or hydraulically or pneumatically with the help of Pressure reducing valves or the like. However, all of these solutions have in common that one or more additional ones Connections in the form of electrical lines or additional pipelines between the servomotor and the control panel, where the feedback is to be registered are required. Especially in systems where the servomotors and the control panel are far apart, this leads to considerable additional costs.

Feedback can also be obtained with the aid of a flow meter, which measures the size of the oil quantity which flows out into the pressure oil line leading to a servomotor when the servomotor is pressurized. This Procedure does not require additional piping, but is exactly like that because of the cost of flow meters

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already mentioned procedure relatively expensive. Further does it lead to reasonably reliable results only in systems with fairly large servomotors, because a flow meter measures the total amount of oil that is exposed to pressure of a servomotor flows out into the pressure oil line, and this includes the entire amount of oil except for the actual oil The volume applied to the servomotor also includes the amount of oil used to compensate for the expansion of the pressure oil line and the compression of the pressurized oil as well as any air bubbles trapped in the pressurized oil line will. In systems with relatively small servomotors, the last two contributions are often the same The order of magnitude for the application volume for the Servomotor, and the method is therefore for such purposes not suitable.

In hydraulic control systems, one or two pressure oil lines are usually connected to each servomotor. Two pressurized oil lines are used when the servomotor has two connections for pressurized oil and its movable element is moved in that either one or the other pressure oil line is pressurized, while the one Line that is not under pressure is connected to a tank.

Only one pressure oil line is used if the servomotor has two connections and one of them is constantly under pressure through a ring line common to several servomotors, while the other is connected to the pressure oil line. If the pressure oil line is connected to a tank, the servomotor is kept closed with the help of pressure oil from the ring line. If the pressure oil line is pressurized, the servomotor moves into its open position · Likewise, only one pressure oil line is used if the movement of the servomotor is caused by a spring in one direction while the movement in the

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in the other direction with the help of pressurized oil from the pressurized oil line. For ship installations where the servomotors can be exposed to severe corrosion from the action of seawater and the like, it is also common It is advantageous to feed oil under low pressure to the servomotor housings through a similar ring line, to keep them under a certain overpressure with a lubricant.

For systems of the type in which a pressure and a return line for pressure oil are connected to each servomotor is, a device for displaying the end positions of the working piston of a servomotor has become known from the German Auslegeschrift No. 2.237.244, the pressure line is connected to the return line via a connecting line which has a smaller flow cross-section as the pressure and return lines, e.g. in the form of an axial through hole in the working piston of the Servomotor, which connecting line is open during the actuating movement of the movable element or working piston is held, but is closed in the end positions of this working piston. Such a device is thus Not applicable to servomotors with only one pressure oil line.

In the known construction, it is also prescribed that the amount of oil that is passed through the connecting line flows through, is limited by narrowing a flow gap with the help of a throttle screw. Because the work pressure and so that the differential pressure at this gap can be quite high, the gap must be so small that it becomes very sensitive to dirt and therefore there is a risk that it will become clogged, so that a remote display of the Position of the servomotor is made impossible

Taking their starting point in systems of the type in which bu each servomotor next to at least one pressure oil line a common low pressure oil line of the above

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Kind belongs, the invention aims to create an arrangement for displaying the position of a hydraulic servomotor, no additional cable connections between the control panel and servomotor requires application in connection with servomotors with both one and two pressurized oil lines can find and with which positive feedback is also obtained in each of the cases in which the movable element of the servomotor is stuck for any reason, regardless of whether this is in one of the end positions or in a Intermediate position and happens despite the application of pressure.

According to the invention, this object is achieved in that an adjustable short-circuit passage is provided between the pressure oil line and the low-pressure oil line, which at fully open and fully closed servomotor and when the pressure oil line is pressurized or depressurized is locked, but in any other position of the movable element of the servomotor and when fully open Servomotor the pressure oil line is depressurized or, when the servomotor is completely closed, the pressure oil line with working pressure when pressurized, a small amount of oil is allowed to pass between the pressure oil line and the low pressure oil line, which actuates a display element attached at a distance from the servomotor in connection with the pressure oil line.

If the servomotor is working correctly, the aforementioned short-circuit passage occurs when the servomotor is fully open and with Working pressure of the pressurized oil line and with the servomotor fully closed when the pressure oil line is depressurized, locked while in every intermediate position between the fully open and fully closed position and also, if when the servomotor is fully open, the pressure in the pressure oil line drops to zero or when the servomotor is fully closed the pressure in the pressure oil line rises to full working pressure, oil flows through the pressure oil line and is actuated said display organ.

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AO

The installation of the device according to the invention for displaying the servomotor position only requires the creation of the aforementioned adjustable short-circuit passage between a pressure oil line and the low pressure line, which are mostly both present in advance, and the assembly of the indicator »In systems without a low-pressure oil line, such a line must also be laid, which however, can be common for a large number of servomotors and therefore only causes modest additional costs.

In systems with only one pressure oil line, oil can flow through the pressure oil line in both directions and operate the indicator. In systems with two pressure oil lines in addition to a low pressure oil line, the short-circuit passage is arranged only between the one pressure oil line and the low pressure oil line, and the display element is linked to the pressure oil line that is connected to the short-circuit passage.

In a preferred embodiment of the invention, the short-circuit passage is regulated by a spring-loaded one Check valve arrangement in a mounted on the servomotor housing and with both the pressure oil line and the Low-pressure oil line connected signal valve with one influenced by the position of the movable element of the servomotor Actuating device for the check valve arrangement.

The short-circuit passage can hereby be provided in a simple manner in direct connection to a hydraulic servomotor will.

In this embodiment, said actuating member can comprise a spring-loaded pressure pin which is displaceable is mounted in the signaling valve and protrudes with its one end from this and there with a movable Element of the servomotor coupled cam element is in engagement, which cam element for said one end of the pressure pin mutually offset contact surfaces which has the completely open and completely closed

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NEN servomotor and intermediate positions of the movable element of the servomotor correspond.

This curve element becomes with a number of recesses as a system for the said end of the pressure pin when the servomotor is fully open and in a number of discrete intermediate positions of the moving element of the servomotor between the fully open and fully closed servomotor formed corresponding end positions, can in addition to the actual feedback function also in a simple manner the possibility can be achieved of holding the movable element of the servomotor in such intermediate positions, and even with servomotors where there is between the position of the movable element and the oil pressure in the pressure oil line there is no proportionality.

The display element can be formed by a control valve in the pressure oil line between the servomotor and a control valve to switch the servomotor between opening and closing function switched on indicator valve with a Through-flow cylinder, which forms a piece of the pressure oil line, and a spring-loaded slide which is slidably mounted in it and which, when there is no oil, flows through the pressure oil line flows through, assumes a rest position and, when oil flows through the pressure oil line, depending on the direction of flow of the oil either in one or in the other Direction is moved from this rest position.

In connection with such an indicator valve, the feedback can be achieved in a simple manner in that the slide is led out of the indicator valve for the purpose of direct visual indication whether it is in its rest position is located or has been moved away from it in one direction or the other.

Ea, however, an electrical feedback can also be achieved, s.B «with the help of one or more lamps, namely in that in the indicator valve in connection with the slide

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an actuator influenced by its movement in one or the other direction from the rest position is provided for an electrical display device, which indicates that the slide is not in the rest position is located.

In systems of the type in which the servomotors overcome a variable closing force, e.g. a spring force or an accumulated e.g. pneumatic pressure, and the required opening pressure from the The current position of the respective servomotor is dependent and a certain minimum pressure must be applied to To move the movable element of the servomotor away from the fully closed position, the display element can easily Way can be formed by a pressure gauge attached to the pressure oil line.

While the feedback is usually achieved solely as an indication of whether the servomotor is about to to make an adjustment movement, or whether he is intentionally or unintentionally in one or the other other end position is in systems of the latter type by using a signaling valve with an actuator in the form of a cam element cooperating with a pressure pin, such as the one described above, in a simple manner Way, a direct feedback of the assumption of the mentioned intermediate position of the servomotor can be achieved.

The invention is explained in more detail below with reference to the schematic drawing. It shows

Fig. 1 and 2 on the basis of block diagrams different hydraulic Control systems with a single servomotor and a device according to the invention for displaying the position of the servomotor,

3 shows a longitudinal section through an embodiment of a Position indicator control valve,

U and 5 show a longitudinal section or a "η cross section of an embodiment of an indicator valve,

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6 and 7 show other configurations of hydraulic control systems with a display device according to the invention the position of the servomotor,

Fig. Ö a modification of the position display device for use in a system according to Fig. 6 or 7 and

9 shows another embodiment of an indicator valve with an associated switch actuator.

In Figs. 1 and 2, two different versions of a hydraulic control system are shown, in which an inventive Device for displaying the position of one or more hydraulic servomotors is used. In both figures, for the sake of clarity, only a single hydraulic servomotor 1 is shown, which per se may be of well known configuration and include a movable member such as rotatable or axially displaceable Slide that opens when the servomotor is pressurized the machine part, e.g. a valve spindle, which is to be actuated by the servomotor, acts.

In the system according to Fig. 1, the hydraulic pressure medium, which is usually oil, the servomotor 1 through a single pressure oil line 2, the oil supply to Pressurized or to open the servomotor 1 with the help a symbolically shown control valve 3 is accomplished, which partly with a pipeline for oil under Working pressure is connected, partly connected to a return line is by the individual pressure oil line 2 both as a feed line and as a return line for the pressure oil to or from the servomotor 1 is used. In the position shown in Fig. 1, the control valve 3 is set such that the Servomotor 1 is pressurized with oil, i.e. it opens. If the control valve 3 is moved to the left in 1 switched, the pressure oil line 2 is instead connected to the return line.

Usually, a hydraulic control system comprises the concerned type a significant number of servomotors such as

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the servomotor designated by 1 with associated control valves such as the control valve designated by 3, and these Control valves can be at a relatively large distance from the servomotors following one for all servomotors common control panel be arranged.

A prerequisite includes a control system in which a position display device according to the invention is used can also find a common low-pressure oil line 4 for several servomotors through which the servomotor housing If necessary, e.g. as corrosion protection, low-pressure oil can be supplied to keep it under a certain overpressure to hold with a lubricant. As already mentioned, such a lower pressure oil line can be used as a common ring line be trained.

For the purpose of obtaining feedback on the position or the working status of the servomotor 1 to the common control panel which, as said, can be arranged at a large distance from the servomotor, is, according to the invention, between the pressure oil ducts 2 and the low-pressure oil line 4 an adjustable short-circuit passage 5 is provided, which when fully open and fully closed servomotor 1 and blocked when the pressure oil line 2 is pressurized or depressurized is, but in any other position of the movable element of the servomotor 1 and when the servomotor is fully open the pressure oil line 2 is depressurized or, when the servomotor is completely closed, the pressure oil line 2 has working pressure applied to it If a small amount of oil is allowed to pass between the pressure oil line 2 and the low pressure oil line, which actuates a display element 6, which in connection with the pressure oil line 2 at a distance from the servomotor 1, e.g. on the common Control panel, is attached.

In the system according to FIG. 2, the supply of Pressure oil to a servomotor 7 via separate pressure oil lines Ö and 9 by actuating a symbolically represented and with 10 designated control valve depending on whether

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the servomotor should open or close, namely one pressure oil line is pressurized and the other is connected to the tank through the return line. In this system, which is otherwise set up in the same way as the system according to FIG. 1, the short-circuit passage 5 between the low-pressure oil line U and one of the pressure oil lines, e.g. the line 8 used to open the servomotor, and the display element 6 are connected with the same pressure oil line, ie the line Ö, arranged.

The oil flow through the short-circuit passage 5 can be regulated with the help of a spring-loaded non-return valve arrangement in one attached in connection with the servomotor 1 and both to the pressure oil line 2 or 8 and the low pressure oil line 4 connected reporting valve with a the actuator for the said check valve arrangement influenced by the position of the movable element of the servomotor. Fig. 3 shows an embodiment of such a reporting valve. The valve includes a housing 11 with pipe connections 12 and 13 for the pressure oil line 2 and the low pressure oil line 4. In the housing 11 an axial cylindrical blind hole 1 / f is formed, in which is partly a tubular body 15, partly a front bushing 16 is attached. In the body 15 is a working cylinder formed, the walls of which have paragraphs 18 and 19 for a shoulder part 20 on a valve sleeve 21 and a Pressure washer 22 for a loading spring 23, indicated only schematically, for a valve body 24, which is provided with a valve seat cooperates, which at the in relation to the shoulder part 20 opposite end of the in the inner Part of the valve body 15 screwed valve bushing 21 is formed.

In front of the paragraph Id, the tubular body 15 forms together with the end bushing 16 a space 25 which is connected to the connection 13 for the low-pressure oil line, namely through channels 26, which in the body 15 at the level of the school

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terpartie 20 of the valve sleeve 21 are formed.

At its opposite end with respect to the space 25, the working cylinder 17 is connected to the connection 12 for the pressure oil line via passage channels 27. In this end of the working cylinder and in a narrowed extension 28 of the axial blind bore 14 behind the tubular body 15, a flow regulator slide of a known design is also attached with a slide body 29 located in the working cylinder 17, in which a longitudinal channel 30 is formed is connected by transverse channels 32 to the above-mentioned connecting channels 27 to the connection 12 for the pressure oil line and is connected to the interior of the working cylinder 17 by a nozzle-like channel 33 with a small flow cross-section. The position of the sliding body 29 and thus the regulation of the passage from the connection 12 for the pressure oil line to the working cylinder 17 is, in a known manner, partly dependent on the cross section of the nozzle-like channel 33 ' Oil can only flow through the channel 33 when there is a differential pressure at this. This differential pressure acts in the other on the end surfaces of the slider body 29 · When the differential pressure has reached a value that can overcome the spring force _t the slide body moves in that direction, where the pressure is minimum, and thereby reduces the flow cross section in the transverse channels 27 and 32 to a value that corresponds to the spring force. The amount flowing through is therefore not dependent on the pressure in the working cylinder, but only on the differential pressure at the channel and the cross section of the same. Since the differential pressure is very small, for example approx. 2 kp / cm, the cross section of the channel 33 can be quite large. The slide body 29 only blocks the flow when such a flow is present. If there is no flow, the sliding body goes back into

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its intermediate position, which is why this system has a tendency to clean itself if dirt gets into it should. In addition, the low differential pressure on channel 33 means that the flow rate is almost independent of which is whether the flow from the very high working pressure in the pressure oil line to the low pressure or from the low pressure to the Pressure zero in the pressure oil line is directed.

The end bush 16 has a through axial bore 3 $, the space 25 towards a shoulder 39 forms for a shoulder portion 40 on a spring-loaded pressure pin 41 with a from the valve housing 11 protruding part 42 and one between the shoulder part 40 and the shoulder part 20 of the Valve sleeve 21 attached loading spring 43 · On a narrower part 44 of the pressure pin 41 is a valve body 45 attached, which is loaded by a spring 46, which against the side of the shoulder section 40 facing the space 25 rests. The valve body 45 is used to close the dem The opening of the continuous axial bore 47 in the valve bushing 21 facing the space 25.

The spring-loaded valve body 24 forms together with the valve bushing 21 a first check valve, which both is loaded by the loading spring 23 as well as by any oil pressure in the working cylinder 17 in the closing direction.

The valve body 24 extends into the continuous axial bore 47 into it, namely with an actuating and control part 40, the free end of which abuts the pressure pin 41 forms, so that when the pressure pin 41 is axially displaced to the right in FIG. 3, the valve body is out of the closed position is moved away. The aps the valve housing 11 outstanding The end 42 of the pressure pin 41 is in engagement with a curve element 50, which is only shown schematically. which is coupled to the movable element in the servomotor 1 in such a way that it moves synchronously with this element, and which is designed with mutually offset contact surfaces 51, 52 and 53, which the fully open servomotor,

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correspond to the fully closed servomotor or intermediate positions of the movable element of the servomotor. Addicted From the design of the movable element in the servomotor 1, the cam element 50 can have the shape of a rotatable Ring or, as can be seen from Fig. 3, an elongated element displaceable in its longitudinal direction own.

In the position shown in FIG. 3, the cam element 50 assumes a position that corresponds to the fully open servomotor corresponds, which means that the actuator 1 with the aid of the control valve 3 in Fig. 1 or the control valve 10 has been acted upon with pressurized oil in FIG. 2, so that its movable element has one of its two end positions has taken. In this position of the curve element 50 is the spring-loaded in the direction of the curve element Push pin 41 at a distance from the end of the actuating slide 4 # of the valve body 24 so that that of the valve body 24 valve formed together with the valve socket 21 the flow path from the working cylinder 17 to the space 25 and thus blocked from port 12 to port 13.

If the control valve 3 in FIG. 1 or the control valve 10 in FIG. 2 is now switched over, because the servomotor 1 should close, oil begins to flow from the servomotor to the return line. At the same time, the moving begins Element of the servomotor to move in the direction of its other end position. This makes the curve element 50 shifted downward in FIG. 3, so that the pressure pin 41 due to the engagement of its protruding end 42 with the contact surface 53 is moved a little into the valve housing and to rest against the actuating slide 4 $ of the valve body 24 is brought. As a result, the valve body 24 opens the valve without the valve body 45 in this position of the pressure pin closes the opposite opening of the through axial bore 47 in the valve sleeve 21, so that it is made possible that between the

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/ 3

Pipeline connections 12 and 13 of the signaling valve for the pressure oil line or the low pressure oil line oil in very little Crowd can flow through it.

When the movable element of the servomotor 1 then its end position corresponding to the fully closed servomotor assumes, the cam element 50 is shifted even further, so that then the contact surface 52 with the protruding End 42 of the pressure pin 41 is engaged, which Pressure pin thereby the valve body 24 even further in the Moved opening direction, but at the same time a closure of the space 25 facing opening of the continuous axial Bore 47 in the valve bushing 21 with the aid of the spring-loaded valve body 45 allows. In this situation is the Oil pressure in the pressure oil line and thus in the working cylinder 17 has dropped to zero, while in space 25 a relatively high lower oil pressure originating from the low-pressure oil line prevails. However, since the valve through the valve body 45 is closed, the oil has no way of flowing over from the space 25 into the working cylinder 17.

Then the control valve 3 in Fig. 1 or the control valve 10 is switched back into the open position in FIG. 2, the servomotor 1 is pressurized so that its movable element begins to move into the end position corresponding to the open servomotor and the cam element 50 is shifted upward in FIG. 3, whereby the protruding band 42 of the pressure pin 41 is disengaged with the contact surface 52 and is brought into engagement with the contact surface 53. With this movement the opens Valve body 45 the valve on the side facing the space 25, but without it on the other side of the valve body 24 is already closed again, so that as a result of the pressure in the pressure oil line now 01 in a small amount from Port 12 flows through the working cylinder 17 to space 2 5 and port 13. Once the moving Element of the servomotor 1 again its completely closed

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If the servomotor has assumed the corresponding end position, the pressure pin 41 is again in contact with the actuating slide 4Ö for the valve body 24 leave so that the valve body 24 closes the valve and thus blocks the passage of oil from connection 12 to connection 13.

With the servomotor fully open, we, nn working pressure in cylinder 17 prevails, so the closed valve body 24 blocks the oil passage, and when the servomotor is completely closed it is the valve body 45 that prevents the oil from passing through.

If now the control valve 3 in Fig. 1 or the control valve 10 in Fig. 2 with the servomotor fully closed in the opening position is switched, whereby the pressure oil line 2 in Fig. 1 or the supply line Ö in Fig. 2 with working pressure is applied, but it turns out that the force developed by the servomotor 1 is not sufficient to drive the machine part, e.g. to move a valve, which is to be operated by the servomotor, so that the movable element of the Servomotor stops in its end position corresponding to the closed servomotor, the cam element 50, which in this situation engages with the contact surface 52 with the protruding end 42 of the pressure pin 41 is located, not up, moved. Therefore, the valve body 24 is then in an open position, which has the effect of that the working pressure in cylinder 17 would otherwise

, the valve body 45 opens the closed valve, so that a small amount of oil from the working cylinder 17 to the space 25 and thus can flow from port 12 to port 13. As a result, in this situation, i.e. when blocked Servomotor, nevertheless achieved a weak oil flow in the pressure oil line, which the display element 6 can operate.

If, conversely, the control valve 3 in FIG. 1 or the control valve 10 in FIG. 2 with the servomotor fully open in brought its closed position and it shows that the closing force developed by the servomotor from some

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Reason is not large enough to move the machine part that the servomotor is supposed to operate, so that the movable element of the servomotor stops in its end position corresponding to the fully open servomotor, in which the pressure pin 41 with the contact surface 51 of the cam element 50 is engaged and from the actuating slide 4Ö for the valve body 24 is removed, so that the valve on the valve body 45 is opened, but closed on the valve body 24 is, a small amount of oil flows from the space 25, which is in communication with the low-pressure oil line, to the working cylinder 17 »since the pressure in space 25 is sufficient to move the valve body 24 into the open position, and there the pressure in the working cylinder has dropped to zero because the pressure oil line is connected to the return line.

In this second situation with a blocked servomotor, too, an oil flow is created in the pressure oil line in this way achieved, which actuates the display element 6 in FIG.

Finally, the movable element of the servomotor 1 during its movement from the one end position on the other hand for the purpose of opening or closing the servomotor due to any obstacle in any Position stopped between the end positions, so that the flow of pressurized oil to or from the servomotor 1 itself stops, a slight flow through the signaling valve is also achieved in this situation, because both check valves on the valve bodies 24 and 45 are open. If such a movement occurs during an opening movement Blockage is the oil flow from port 12 for the pressure oil line to port 13 for the low pressure oil line directed, and if the blockage occurs during the closing movement, the direction of flow is opposite.

It can thus be seen that as long as the movable element of the servomotor 1 is between its end positions or in situations in which it is

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has set in one of the end positions, although it has been caused to move in the direction of the other end position by the application of pressure or pressure release, the controllable short-circuit passage according to the invention, the ζ · Β. is realized by the signaling valve according to FIG. 3, ensures an oil flow in the pressure oil line. The possibilities for creating this oil flow used for display purposes are not limited to the embodiment shown in Fig. 3 with a signaling valve which is attached directly to the servomotor, since in principle only the possibility of actuating the spring-loaded check valve arrangement with the valves at 2k and 45 in Depending on the respective position of the movable element of the servomotor must be given, which can also be achieved in other ways than by actuation through direct contact such as that illustrated in FIG. 3. Furthermore, the check valve arrangement, which regulates the short-circuit passage directly, does not need to be assembled with the flow regulator slide which regulates the amount of oil flowing through the short-circuit passage.

The display member 6 in Figs. 1 and 2, which both during the adjusting movement of the movable element of the Servomotor 1 as well as in the above-mentioned situations in which this element is either in an end position or in an intermediate position between the two end positions is blocked in the pressure oil line to sense the oil flow occurring can be fed into the pressure oil line 2 in FIG. 1 or the feed line β In Fig. 2 between the servomotor 1 and the control valve 3 or 10 switched on display valve with a through-flow cylinder, which represents a piece of the pressure oil line, and a spring-loaded one slidably mounted therein Slide are formed which, when there is no oil flow in 5 of the pressure oil line, assumes a rest position and

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AJ ₁ ² - ³⁹

in the presence of an oil flow through the pressurized oil] device is moved away from the rest position depending on the direction of flow in one or the other direction.

FIG. 4 shows an embodiment of such an indicator valve with a housing 54 in which a throughflow cylinder 55 is formed which has two pipe connections 56 and 57 for the pressure oil line 2 in FIG. 1 or the feed line 8 in FIG. 2 on its end faces . In the through-flow cylinder 55 there is a spring-loaded, axially displaceable slide with a slide body 58 and a schematically indicated loading spring 59, which is arranged between two pressure rings 60 and 61, which press against an abutment ring 62 firmly connected to the valve housing or a shoulder section formed by the slide body 58 63 and an annular shoulder surface 64 bear against the wall of the through-flow cylinder 55. In the direction from bottom to top in Fig. 4, the oil flow moves through the valve port from the terminal 57 through channels 65 in the lower part of the slider body ren _t ^ 5 to a through cutouts

20- ia the wall of the through-flow cylinder 55 or in the slide body 58 formed space 66, which in the position shown in Fig. 4 by contact between contact surfaces on opposite, annular projections 67 and 68 on the wall of the throughflow cylinder 55 and on the slide body 58, respectively is locked at the top. Above these projections there is a recess in the wall of the through-flow cylinder or space 69 formed in the slide body, which is formed by axially parallel channels 70 in a projection of the wall of the through-flow cylinder, which the already mentioned annular contact surface 64 for the one thrust washer 61 of the loading spring 59 forms, is in communication with a space 71 surrounding the loading spring 59, which space is formed by channels 72 between the valve housing and the abutment ring 62 for the other pressure disk 60 of the loading spring 59 is connected to the pipe connection 56. In an im

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Slide body 5Ö formed axial, cylindrical bore 73, which are connected at the bottom through channels 74 with the flow-through space 66 surrounding the lower part of the slide body stands and is closed at the top by a plug 75 and a transverse pin 76, the ends of which the plant for the form a pressure ring 60 of the loading spring 59 is a flow regulator slide of the same configuration as that Flow regulator slide between the working cylinder 17 and the connection 12 for the pressure oil line in the signaling valve used according to Fig. 3. The channel 70 running in the longitudinal direction is in the flow regulator slide in FIG. 4 Slide body 77 through a nozzle-like channel 79 in connection with the lower part of the cylindrical bore 73 as well as through transverse channels 00 and therewith corresponding transverse η channels oil in the valve body 5Ö in connection with the aforementioned space 69 between the slide body 5Ö and the wall of the through-flow cylinder 55.

If there is no oil flow through the pressure oil line and thus through the through-flow cylinder 55, the slide body 50 assumes the rest position shown in FIG 69 blocks. This situation occurs both when the pressure oil line is under full working pressure after the setting of the servomotor has been completed, and when this line is depressurized. However, if an oil flow moves in one direction or the other through the pressure oil line, the slide body is moved away from the rest position shown in FIG. 4 against the force exerted by the loading spring 59 and thus opens the oil passage between the aforementioned spaces 66 and 69 surrounding the valve body, so that the oil flows through the channels 65, the space 66, the space 69, the channels 70, the space 71 and the channels 72

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can flow through the cylinder 55 unhindered. As soon as the flow stops again, the valve body reverses 5β returns to the rest position shown in FIG. 4 under the influence of the force exerted by the loading spring 59. The flow regulator slide 77 has the effect that even in the rest position shown in FIG. 4, in which the oil passage between the spaces 66 and 69 is prevented, a small amount of oil can flow through the indicator valve without that the slide body 53 moves away from the rest position will. However, the flow cross section of the channel 79 is smaller than the flow cross section of the corresponding one Similar to a nozzle & n channel 33 in the flow regulator slide in the signaling valve according to FIG. 3 · This has the effect that that amount of oil which can flow through the channel 33, the channel 79 cannot happen, but causes the slide body 5 # to move away from its equilibrium position. The flow control slide of the indicator valve sets in this way, a threshold value for the display function is set. However, this can also be achieved by means of a throttle screw in a bypass connection between bores 56 and 57 be replaced, since between these bores there can be at most a differential pressure that depends on the force of the loading spring 59 is determined. He can also by a suitable clearance between the slide body 58 and the Housing 54 must be replaced. It is only important that the oil, which can flow through the channel 33, not between the bores 56 and 57 can pass without moving the slide body 5Ö out of its equilibrium position .

The movement of the slide body 5Ö of the indicator valve its rest position shown in FIG. 4 can in principle be used for direct visual display, namely in that the slide body is arranged with an outside of the valve housing 54 in a manner not shown in detail Pointer organ is connected, which is synchronized with

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moves the slide body 5β with respect to an indicator scale, on which the rest position is marked. When the servomotor 1 in Fig. 1 or 2 is either open or closed and the pressure oil line is pressurized or depressurized, the pointer element is above the rest position marking. As soon as either during the setting of the Servomotor or due to a blockage of the movable element of the same an oil flow through the signaling valve according to Fig. 3 created short-circuit passage and is thus caused by the pressure oil line, moves However, the pointer organ moves away from the rest position marking, so that a direct visual control of the function of the servomotor is reached.

In a preferred embodiment, however, the movement of the slide body 50 from its rest position is to be achieved exploited an electrical display, namely that in the display valve in connection with the slide body one influenced by the movement of the slide body in one direction or the other from the rest position Actuator is provided for an electrical display arrangement. In the illustrated embodiment of the indicator valve, this actuator consists, as from the cross-section in Fig. 5 emerges in more detail, from a in a with respect to the through-flow cylinder 55 transversely Bore Ö2 rotatably mounted spindle Ö3, which has one in the Slide body 5Ö engaging actuating arm Ö4 has, with whose help the spindle Ö3 is rotated when the slide moved away from its rest position in one direction or the other. This rotational movement of spindle # 3 in the one or the other direction is via a switch actuator Ö5 attached to the spindle to operate Switches used in an electrical display circuit, not shown in detail, so that in this way a display which is achieved that the slide body 5Ö from has moved away from its rest position in Fig. 4 ·.

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As can be seen in more detail from FIG. 5, the spindle 83 is also axially displaceable and mounted in the bore 82 under spring loading. The bore 82 forms a chamber which is in connection with the through-flow cylinder 55, so that a part Ö6 of the spindle located in this chamber with an enlarged cross-section is acted upon at full oil pressure in the through-flow cylinder in such a way that the spindle 83 moves against that of one between two Pressure washers 87 and && attached loading spring 89 moved in the direction of a position in which the switch actuator 85 actuates an additional switch 90, which is a component of the electrical display circuit. If there is no oil pressure in the through-flow cylinder 55, the spindle 83, on the other hand, assumes the position shown in FIG. 5 under the influence of the loading spring 89, in which the said switch 90 is switched off.

The device of the electrical display circuit, not shown, which is actuated by the spindle 83 via the switch actuating member 85, can for example be such that the switches actuated when the spindle 83 is rotated start a flasher relay to which a lamp is connected and at the same time switch off the additional switch mentioned. so that the lamp does not light up when the pressure oil line is depressurized and the slide of the indicator valve assumes the rest position shown in Fig. 4, while it lights up constantly when the slide of the indicator valve is in its other stationary position when the servomotor is open and the pressure oil line is at full working pressure State. When the spindle 83 is rotated by an oil flow through the indicator valve in one direction or the other, the lamp flashes, so that in this way a clear electrical indication is obtained of whether the servomotor is open or closed or whether it is about to perform a Actuating movement is initiated. Due to the duration of the period in which the lamp flashes, an additional

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- Display reached for whether the servomotor is working correctly or whether its moving element is stuck.

FIGS. 6 and 7 show a modification of the display member when using a position display device according to the invention in connection with a servomotor of the type illustrated, which overcomes a variable closing force is opened, so that the pressure required for opening depends on the current position of the movable element of the servomotor is dependent, and therefore zwisehen the pressure in the pressure oil line and this momentary position is proportional. The figures only show that part of the system which is set up differently than in FIG. 1. The pressure oil line 2 and the low pressure oil line 4 are therefore connected to a servomotor 1 and a controllable short-circuit passage 5, exactly as in FIG. 1, the can be created with the aid of an alarm valve such as that shown in FIG. In Fig. 6 is the working pressure line and the return line is thought to be connected to a motor-pump system, and, as is symbolically indicated, a Control valve 9Ö used, which apart from an open position and a closed position, which are indicated by the same symbols as those used in FIG. 2, also one Has a neutral position in which the pressure oil line 2 via a pilot-controlled check valve 99 with the return line is connected.

Correspondingly, the working pressure line in FIG. 1 is connected to a hand pump unit 100 with a flow cross section connected in such a way adapted power in the signaling valve in FIG. 3 that an 01 flow bypassing the servomotor in the pressure line and through the signaling valve only corresponds to a small part of the pump output. In connection In this embodiment, the control valve 101 is thus set up in such a way that it makes the pressure oil line 2 drop-tight can shut off. Both in Fig. 7 and in Fig. 8, the display element consists in a simple manner of a manometer

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meter 102 with a scale with fully open and fully closed Markings corresponding to the servomotor.

In systems of the type described here, as already mentioned, it is possible to switch the servomotor to intermediate positions Bringing, i.e. its movable element in intermediate positions between the two end positions, that of the fully open and fully closed servomotor correspond to hold. In connection with this it is often acceptable that the number Such possible intermediate positions are limited to a certain number of fixed positions, e.g. 10 ^ -iger Opening, 25 ^ -iger opening, 50 ^ -iger opening, etc. between the correspond to the end positions corresponding to the fully closed and fully open servomotor.

In such cases, a position display device according to the invention can be easily modified with a display device in the form of a manometer, for example, that it also indicates that the movable element of the servomotor is in one of these discrete intermediate positions. to for this purpose, as shown in FIG. 8, the one with the movable Element of the servomotor coupled, for actuating the signaling valve according to FIG. 3 serving cam element, which in this figure is denoted by 103, are formed with a number of recesses, each one of the intermediate positions mentioned are assigned so that the pressure pin 41 in Position indicator control valve, which is only shown in outline in Fig. 8, by engagement between the protruding End 42 and one of these recesses 104 out of engagement with the actuating slide 48 for the valve body 24 brought so that the check valve arrangement is placed in the same state as when the servomotor is fully open.

To open the servomotor in a system according to FIG. 6, the control valve 98 is brought into the open position, which is marked by the symbol on the outside left, so that oil is released through the control valve 98 and the pilot-controlled check valve 99 in the pressure oil line 2 and through this to

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Servomotor 2 flows. Except in the aforementioned discrete intermediate positions a small amount of oil flows through the short-circuit passage during the opening movement of the servomotor to the low pressure oil line.

When the servomotor is fully open, the check valve 99 closes and the control valve 9Ö is switched to the in brought the neutral position shown in the figure, so that the servomotor stops in the fully open position, which is on Manometer 102 can be read.

To close the servomotor, the control valve 9Ö is brought into the closed position shown by the symbol on the outside on the right in FIG. 6, so that the pilot-controlled check valve is opened for the purpose of returning oil to the return line. Simultaneously with this, the pressure on the manometer 102 drops to zero, which can be observed on the manometer 102, and when the servomotor is closed, the control valve 9Ö is brought back into the neutral position. The pressure gauge should then show zero. However, if one suspects that the servomotor is not completely closed, but has got stuck in some intermediate position, the control valve 90 is once again very briefly brought into the open position and then again into its neutral position. As a result, the servomotor opens a little with respect to the position it has assumed, in order to then close again very slowly, in that oil flows from the pressure oil line 2 to the low pressure oil line 1+ . One observes again the pressure display on the manometer. If the pressure suddenly falls from a value that is higher than the minimum pressure required to initiate the opening movement to zero, the only reason for this can be that the servomotor is mechanically prevented from closing. If, on the other hand, the pressure suddenly drops from the value that corresponds to the minimum pressure to zero, you know that the servomotor is completely closed.

If the servomotor is to be brought into one of the discrete intermediate positions shown in FIG

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Control valve 98 is placed in the open position until the movable element of the servomotor has moved past the desired intermediate position in the course of its opening movement. Thereafter, the control valve 98 is brought into the neutral position, whereby the servomotor closes slowly until the protruding end 42 of the pressure pin 41 of the position indicator control valve engages in the closest recess 104 in the cam element IO3, in which the movable Element is then held. On the manometer 102 it can be read off whether the desired intermediate position has been taken has been. If the servomotor is to be closed further, the control valve 98 is briefly in the closed position and then brought back into the neutral position, whereby the movable element of the servomotor again slowly moved in the closing direction until the protruding end 42 of the pressure pin 41 into the next recess IO4 engages in cam element 103.

If during the opening of the servomotor it turns out that the movable element is blocked, the control valve 98 is switched to the neutral position, whereby the pressure drops quickly to zero, since the oil flows through the check valve 99 back to the return line, so that here an indication of an inadequate opening function of the servomotor is achieved.

In the embodiment shown in FIG. 7, the procedure is essentially the same, except that, as already mentioned, a hand pump unit 100 is used instead of the motor pump unit, and the control valve 98 and the check valve 99 in FIG. 6 are drip-tight blocking valve replaced. The operating process when opening and closing the servomotor and when taking one of the intermediate positions as well as the registration with the aid of the manometer 102 takes place mainly in the manner explained above.

Although the embodiment shown in FIG. 8 of the cam element coupled to the movable element of the servomotor

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is especially suitable for use in conjunction with the aforementioned servomotors of the type in which the opening takes place under overcoming a variable closing force and with the application of this cam element also bezüglieh the assumption of the discrete intermediate positions of the movable element of the servomotor a positive feedback can be achieved, this cam element provided with recesses can also be used in conjunction with a servomotor of the type described with reference to FIGS. 1 and 2 apply, with no proportionality between the There is pressure in the pressure oil line and the position of the movable element of the servomotor. Even with one of these Servomotor is thereby achieved the particular advantage that the movable element can be brought to a Number of discrete intermediate positions between those corresponding to the fully open and fully closed servomotor Take end positions because the movable element of the servomotor as a result of the engagement between the recesses formed cam element and the protruding end 42 of the spring-loaded pressure pin of the signaling valve in such intermediate positions can be recorded. In this special case there is no clear feedback achievable whether the movable element of the servomotor is held in an intermediate position, but in many cases there is also no need for this, since an experienced operator decides on the control without difficulty can determine the position of the servomotor.

The assumption of an intermediate position can take place in such a servomotor that the servomotor with Help of the control valve on the intermediate position that he is to take, is opened out, after which the control valve is brought into its neutral position. The servomotor then moves very slowly in the closing direction up to the first intermediate position. Should the servomotor continue are closed, the control valve is very briefly in the

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Closed position and then brought back to the neutral position. The servomotor then moves again very slowly in the closing direction until it reaches the first intermediate position has, etc. Continue in this way until the servomotor is in the desired intermediate position.

When using the position display device according to the invention in connection with servomotors of the type in which the opening movement overcoming a variable Closing force takes place and in which, as explained with reference to FIGS. 6 and 7, a feedback regarding the taking of a number of intermediate positions by the movable element of the servomotor can be achieved as Display member in place of the manometer 102 shown in FIGS. 6 and 7, an electrical display device in FIG Find connection with an indicator valve application, which is designed in the same way as the indicator valve in principle according to Fig. 4

In Fig. 9 is an embodiment of such an indicator valve reproduced, which in this case is coupled directly to a control valve designed as a control valve which corresponds to the control valves 3 and 10 in FIGS. 1 and 2, respectively. This control valve that is in a control panel is installed, has an operating lever 105, which is rotatably mounted in the housing 106 of the tap and by a divider spring 107 can rotate via a running disk 10Ö and a needle roller assembly 109 actuated spindle 110, which is fixed to a Distributor housing 111 is connected, the end face of which rests oil-tight, but rotatably against a distributor disk 112, which is fixedly connected to an elbow 113, which at the opposite end with respect to the operating lever 105 of the housing 106 is screwed on in an oil-tight manner. The elbow 113 partially has a pipe connection 114 for the relevant Servomotor leading pressure oil line, which corresponds to the pressure oil line 2 in Fig. 1, partly through holes 115 and 116 for the supply of oil under working pressure

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or for the return of return oil to a tank through pipelines for several control valves of the embodiment shown can be together.

In the figure, the control valve is shown in the neutral position. By turning from this position to one side or the other, the working pressure line 115 or the Return line 116 connected to a channel 117 which extends through the distributor disk 112 and a little way into the distributor housing 111. Exactly as in the case of the indicator valve shown in FIG. 4, the distributor housing 111 has a through-flow cylinder 118, in which a spring-loaded slide 119 of basically the same design as the slide 50 in FIG. 4 is attached and which, like this one, is designed with an axial bore in which a spring-loaded flow regulator element is located 120 of basically the same construction as the flow regulator element 77 in FIG. 4. Just like in the embodiment in FIG. 4, the slide 119 therefore decreases in this case when there is no oil flow from the working pressure line 115 to the connection 114 or from the latter connection to the return line 116 takes place, which in the Fi £, ur a rest position shown, in which the oil passage z-.ischen a space 121 connected to the through-flow cylinder, communicating with the flow regulator element 120 through transverse channels 122, and a space 123 in the Spindle 110 is blocked, from where a connection to a distributor housing 111 through transverse channels 124 surrounding space 125, which in turn is connected to the pipe connection 114. In this position of the Slider 119, just as in the embodiment according to FIG. 4, there is only the possibility that by the in the slider 119 located flow regulator element 120 flows over a small amount of oil from channel 117 to space 125.

In the embodiment shown, on the end of the slide 119 facing the operating lever 105, a display

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piston 126 attached, which is provided at its opposite end with a groove 127, which is in the figure rest position shown in engagement with a switch operating rod 128 for an electrical switch 129 is located. Out of consideration for the balancing of the slide 119 with reference on the oil pressure on both sides of the slide is also on the opposite one facing away from the operating lever 105 An extension piston 130 is attached to the end of the slide 119. When the working pressure line 115 by turning the operating lever 105 is connected to the channel 117, the slide 119 is moved from the rest position shown in the figure moved away and in the direction of the operating lever 105, causing the indicator piston 126 to move over the switch operating rod 12Ö the electrical switch 129 is operated. If, conversely, the return line 116 is connected to the channel 117 set, the slide 119 moves away from the operating lever 105, whereby the indicator piston 126 also over the switch operating rod 128 operates the switch 129. This operation of the switch can be done in the same way as those described above can be used, for example, to switch on a flasher relay, so that a lamp can be used is brought to flash and thereby indicate that the slide 119 has been moved away from its rest position, thereby expressing that a flow of oil is moving through the indicator valve.

Since the illustrated embodiment of the indicator valve, as already mentioned, is not particularly suitable for giving positive electrical feedback on the fact whether the movable element of the servomotor has a certain of a number of discrete intermediate positions apart from the fully closed or fully open servomotor assumes corresponding end positions, the indicator valve is additionally assigned a number of position indicator lamps 143, which corresponds to the number of those positions that the movable element of the servomotor should be able to assume, which

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before lamps are switched by a corresponding number of oil pressure switches coupled to the indicator valve, a single one of which is shown in the figure. This oil pressure switch comprises a switch actuating pin 132 movable in a cylinder 131, one end of which can actuate an electrical switch 133 and at its other end is under the action of a loading spring 135 via a piston 134, the spring pressure of which is adjustable, for example, as shown , with the help of a hexagon socket screw I36. In order to ensure oil-tightness, two O-rings 137 and 138 are attached around the shaft of the switch actuating pin I32, of which the former is stationary between two locking rings 139 and which surround the switch actuating pin 132 with a suitable clearance, while the second O-ring 13 # rests against the head of the switch actuating pin 132 actuated by the piston 134.

The space surrounding the switch actuating pin 132 between the two O-rings 137 and I38 is through a Ouerlaufenden channel 141 in the cylinder I3I and a channel 142 in the housing IO6 of the tap in connection with the distributor housing 111 surrounding space 125, so that the same oil pressure prevails in the space mentioned between the two O-rings as in room 125.

Exerted by suitably adjusting des.von of the loading spring I35 pressure of the switch operating pin can be made to, for a given value of the oil pressure between the two O-rings 137 and I3Ö and thus at a given position of the movable element of the servo motor the switch 133 to be actuated, because, as already mentioned, with servomotors of the type described here, which are opened by overcoming a variable closing force, there is proportionality between the position of the movable element of the servomotor and the oil pressure in the pressurized oil line.

This way there is positive electrical feedback

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Taking a number of discrete intermediate positions of the movable element of the servomotor possible, e.g. a 50 ^ opening, a 25 / opening or a 10 ^ opening Opening correspond.

If the control valve with built-in indicator valve according to Fig. 9 in connection with servomotors is used that only either in the fully open or fully closed position should stand, only one oil pressure switch is connected to the indicator valve.

The embodiment according to FIG. 9, in which the indicator valve is assembled with the control valve and is therefore intended for direct fontane in a control panel, is specially designed for servomotors that can only be operated from a single pediatric or control panel. In contrast to this, the embodiment shown in FIGS. 4 and 5 can be switched into the pressure oil line at any point between the control panel and the servomotor and is therefore also suitable for use in connection with servomotors that differ from to control several pediatric and control consoles with different lanes.

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L e r s e i t e

Claims (15)

Claims ,1.' Device for displaying the position of a hydraulic servomotor (1) of the type to which pressure oil is fed through at least one pressure oil line (2.0) and which is also connected to a low-pressure oil line (4) which is common to several servomotors and which is connected to the housing of the servomotor is connected in order to maintain a certain oil pressure in this, characterized in that an adjustable short-circuit passage (5) is provided between the pressure oil line (2,0) and the low-pressure oil line (4), which when the servomotor (1) and is blocked when the pressure oil line (2, δ) is pressurized or depressurized, but in any other position of the movable element of the servomotor (1) and when the pressure oil line (2, δ) is depressurized when the servomotor is fully open or when the servomotor is completely closed the pressure oil line (2, δ) is acted upon by working pressure, a small amount of oil is the passage between the pressure oil line (2, δ) and the corset pressure oil line (4), which actuates a display element (6) attached at a distance from the servomotor (1) in connection with the pressure oil line (2,0). 2. Device according to claim 1, characterized in that said short-circuit passage (5) is regulated by a spring-loaded non-return valve arrangement (24, 45) mounted on the servomotor housing and connected to both the pressure oil line (2,0) and the low-pressure oil line (4) connected signaling valve with an actuating member (41) for the said check valve arrangement, which is influenced by the position of the movable element of the servomotor (1). 3. Device according to claim 2, characterized in that said check valve arrangement has a first check valve (24) which is inserted into the one end of an ar- 809809/0655 ORIGINAL INSPECTED cylinder (1,7) is used, which at its other end via a with the help of a flow regulator element (29) controllable passage with a small flow cross-section with the pressure oil line (2.8) is in connection, so that it is caused to prevent the flow of oil through the pressure oil line (2, δ), during this first Check valve can be moved away from said actuator (41) from the closed position, as well as a second Check valve with a spring-loaded valve body (45), which is slidably mounted on said actuating member (41) so that it is only when it is completely closed Servomotor (l) allows low-pressure oil to flow through from an outside of the working cylinder (17) Space (25) into the working cylinder (17) and from there into the pressure oil line (2, δ) out. 4. The device according to claim 3 » characterized in that said actuating member unfasst a spring-loaded pressure pin (41) which is slidably mounted in the Ileldeventil and with its one end (42) protrudes from this and there with a movable element of the servomotor (1) coupled cam element (50) is in engagement, which cam element for said one end (42) of the pressure pin (41) has mutually offset contact surface (51-53) that the fully open and fully closed servomotor (1) and intermediate positions of the movable element of the servomotor (1). 5. Device according to claim 4 »characterized in _t that said cam member (103) with a number of recesses (104) as an abutment for said one end (42) of the pressure pin (41) fully open servomotor (1) and in a number discrete intermediate positions of the movable element of the servomotor (1) is formed between the end positions corresponding to the fully open and fully closed servomotor. 6. Device according to one or more of the preceding 809809/0655 Claims, characterized in _t that the display member (6) is formed by a in the oil pressure line (2.8) between the servomotor (l) and a control valve (3, 10) for switching the positioning motor is switched on between opening and closing function display valve with a Through-flow cylinder (55), which forms a piece of the pressure oil line (2,8), and a spring-loaded slide (58) slidably mounted therein, which assumes a rest position when no oil is flowing through the pressure oil line and when oil flows through the pressure oil line , depending on the direction of flow of the oil is moved either in one or in the other direction from this rest position. 7. The device according to claim 6, characterized in that a with the help of a flow regulator member (77) adjustable passage with a small flow cross-section is formed in the indicator valve, which allows the flow of a small oil mehge without the slide (5Ö) is moved. 8. The device according to claim 3 and 7, characterized gekennzei c ij 'net that the flow cross section in the display as the valve throughflow area of the passage between · the working cylinder (17) is smaller the signaling valve and the pressure oil lines (2,8). 9. Device according to claim 6, 7 or 8, characterized characterized geke nii in that the slide (58) is constructed from the display valve 1ιύϊ ± purpose of direct visual indication of whether it is or in its rest position s5 <h in the one or de- is moved away from this rest position in the other directioni 10. The apparatus of claim 6, 7 or 8, characterized in that the display valve in communication with the slide via (58) a of the movement thereof in the one or in the other direction from the rest position influenced actuator (83) for eireelektrische display device is provided, which indicates that the slide (58) is not in the rest position. 809809/0655 BATH ORIGINAL 11. The device according to claim 10, characterized in that said actuating member is formed by a spindle (83) rotatably mounted in a with respect to the flow cylinder (55) of the indicator valve transverse bore (82) with a with the slide (58) in Engaging actuating arm (84) for rotating the spindle (83) when the slide (58) is moved in one direction or the other with respect to the rest position. 12. The device according to claim 11, characterized in that that said spindle (83) is also axially displaceable and is spring loaded in its bore (82) and that its one end is in one with the flow cylinder (55) is connected space, so that the spindle (83) is in a first position when the pressure line (2,8) is pressurized with oil and when the pressure oil line is depressurized due to the spring load is moved into a second position, in which first and second position the electrical display device operated so that it indicates that the servomotor is open or closed. 13. Device according to one or more of claims 1-5 and of the type in which the servomotor (1) is opened while overcoming a variable closing force, characterized in that the display element (6) is connected to the pressure oil line (2 ) attached manometer (102) is formed. Device according to Claim 9, characterized in that the said actuating member is formed by an indicator piston (126) fastened to one end * of the slide (119) which, when the slide is moved in one direction or the other , with respect to the rest position is axially displaceable for the purpose of actuating a switch actuating rod (128). 15. The device according to claim 5 and claim 14 and of the type in which the servomotor is opened while overcoming a variable closing force, characterized in _t 809809/0855 that with the indicator valve one of the number of intermediate positions and one end position of the movable element the servomotor corresponding number of oil pressure switches is coupled, each one of a spring (135) with adjustable Contain spring pressure influenced switch actuator pin (132) mounted in a cylinder (131), from which an oil-tight separated section in connection with a part (125) of the through-flow cylinder of the indicator valve stands, so that the switch actuation pin against the adjustable spring pressure of that prevailing in the flow-through cylinder Oil pressure is influenced, the spring pressure in each oil pressure switch is adjusted so that the switch operating pin (I32) at an oil pressure corresponding to a given position of the movable element of the servomotor (1) an electrical switch (133) is actuated. 809809/0655