EP3189240B1 - Hydraulic actuator with a spring actuated fail-safe position - Google Patents

Description

The invention relates to a hydraulic device for driving a hydraulically regulated or to be set actuator with the features of the preamble of claim 1.

Out DE 10 2008 025 054 B4 shows a hydraulic device with which hydraulically an actuator can be regulated or placed with respect to its position. For this purpose, the hydraulic device to a motor which is arranged in a motor housing. To accommodate hydraulic fluid, a surge tank is integrated into the hydraulic device. The motor is coupled to a hydraulic pump disposed in a pump housing, the hydraulic pump being adapted to allow hydraulic fluid to be conveyed in two directions, forward and reverse directions, to precisely control the actuator in both directions or to be able to ask. For this purpose, the hydraulic actuator comprises a drive cylinder having a first and second cylinder chamber and a drive piston arranged therebetween, to which a drive shaft which is displaceable in the longitudinal direction is mounted. The drive axle can be used to move or control elements to be controlled such as valves, switches, robot arms and the like.

From the publication DE 10 2011 012 305 goes out a hydraulic actuator assembly with a control valve, which is provided with an emergency operation. The emergency operation can be triggered electrically or hydraulically. The device according to the aforementioned document is complicated and not optimally designed with regard to the safety and speed of an emergency operation.

The invention has the object of providing a device with the features of the preamble of claim 1 in such a way that it can be prepared and maintained the operational readiness of the device including the emergency shutdown, after reaching the operational readiness a rule-setting or switching operation with high Precision and adaptability can be carried out to the respective application areas and an emergency shutdown can be carried out safely and with high or defined speed. This object is achieved by the characterizing features of claim 1, advantageous Developments emerge from the subclaims 2-15. As the core of the invention, it is initially considered that the device comprises a clamping cylinder for an emergency closing spring. In the tensioning cylinder, a clamping cylinder space and a tensioning piston which can be coupled to the drive axle are arranged. By means of the tensioning piston, the emergency closing spring can be hydraulically tensioned into a tensioning or emergency release position, wherein the tensioning cylinder space is connected to an outlet of the hydraulic pump in such a way that hydraulic fluid can be filled by the hydraulic pressure of the hydraulic pump. As a result, the emergency closing spring is transferred to a cocked position and hydraulically locked in this cocked position by check valves.

With a supply or discharge opening of the clamping cylinder space a controlled seat valve is connected, by which the Notschließfeder can be transferred from the cocked standby position in an emergency release, including both the Notschließfeder holding in standby position, located in the clamping cylinder chamber hydraulic fluid and the hydraulic cylinder located in the first cylinder chamber is removed via the controlled seat valve to transfer the drive axle in an emergency release position.

(Emergency release position may be replaced by emergency position (open or closed))

The hydraulic pump of the hydraulic device thus serves, on the one hand, to tension the emergency closing device and to transfer it to a standby position, but on the other hand, by subsequent operation in the forward and reverse directions, the hydraulic actuator with the drive cylinder in the first and second cylinder chamber and to move to cause a regulation or the start of a certain position of the coupled valve or switch, robot element or the like. The discharge of the clamping cylinder space in the case of emergency release on the one hand and the emptying of the first, the Notschließfeder remote cylinder space of the drive cylinder is effected by one and the same seat valve, which can also be referred to as emergency release valve, the simultaneous discharge of the hydraulic chambers to a very fast response of the emergency release function leads.

The hydraulic device with its emergency stop function is suitable for valves of all types of media and for mechanical actuation. The basic principle is that at Power failure or targeted shutdown by the mechanical spring a defined position in a very short or defined time can be achieved safely. Examples are valves in gas and water pipes, in steam supply to turbines, pipeline valves, valves in chemical plants and electrical switches for high performance and the like ..

Compared to the prior art, both the production of operational readiness as well as the control and setting process or the emergency shutdown of the device is achieved with reduced funds. Advantageously, a regulation of the device is made against the actual process forces acting on the device and not against the force of the emergency closing spring. This leads to a substantial energy saving in the operation of the device. To produce the operational readiness, the potential energy, namely the spring preload is built up and stored with the hydraulic pump, which also carries out a regulating or adjusting process. With the storage a considerable energy saving is connected. If the ready state is established, subsequently a linear displacement or force control of the actuator can be carried out with high accuracy. One or more positions can be approached or switching operations executed. After successful setting or switching operations, the drive of the hydraulic pump can be switched off. If position deviations occur, they can be corrected again. This achieves a further reduction of the required operating energy.

The emergency closing procedure is forced to be triggered in the event of a power failure or disconnection of the seat or emergency valve. The emergency valve executes a positive opening and connects all hydraulic cylinder chambers with the expansion tank and the spring chamber. The preloaded spring can thus move all pistons and especially the linear drive in a defined end position. The closing time is very short or definable, namely in the range of a few milliseconds, with a time definition by installation of throttles or flow control valves is possible. The emergency valve is constructed so that the outflow of the pressurized medium through a conical seat or insert seat occurs in such a way that the media flow opens the valve. The opening can be additionally supported by an opening spring. The valve is closed by an electric magnet or otherwise acting closing mechanisms.

Fig. 1

eine schematische Schnittdarstellung der Vorrichtung mit Antriebszylinder, Spannzylinder, Mitnahmezylinder sowie angeschlossener Pumpe und angeschlossenen Ventilen;

Fig. 2

eine Detailansicht des auch in Fig. 1 klein dargestellten volumenstromabhängigen Zweiwegeventils;

Fig. 3

eine Figur entsprechend Fig.1, jedoch etwas vereinfacht;

Fig. 4

eine Detaildarstellung des im Spannzylinderraum befindlichen Spannkolbens in einer Grundstellung;

Fig. 5

eine Darstellung gemäß Fig. 4, bei der der Spannkolben in Bereitschaftsstellung ist;

Fig. 6

eine modifizierte Anordnung gemäß Fig. 5, mit Spannkolben in Bereitschaftsstellung, wobei mit einer Kupplung im Bereich des Mitnahmekolbens und wobei der Antriebskolben in einer mittleren Regelstellung dargestellt ist;

Fig. 7

eine Darstellung des Not-Schließventils stromlos geöffnet;

Fig. 8

eine Darstellung des Not-Schließventils bestromt in Schließstellung;

Fig. 9

eine Darstellung eines modifizierten Not-Schließventils mit einer den Öffnungsvorgang begünstigenden Rückstellfeder und zwei angebauten Sensoren für die beiden Ventilstellungen.

The invention is based on advantageous embodiments in the drawing figures explained in more detail. These show:

Fig. 1

a schematic sectional view of the device with drive cylinder, clamping cylinder, driving cylinder and connected pump and connected valves;

Fig. 2

a detail view of it also in Fig. 1 small illustrated volume flow dependent two-way valve;

Fig. 3

a figure accordingly Fig.1 but somewhat simplified;

Fig. 4

a detailed representation of the clamping piston located in the clamping chamber in a basic position;

Fig. 5

a representation according to Fig. 4 in which the tensioning piston is in the ready position;

Fig. 6

a modified arrangement according to Fig. 5 , with clamping piston in the ready position, with a coupling in the region of the driving piston and wherein the drive piston is shown in a middle control position;

Fig. 7

a representation of the emergency closing valve normally open;

Fig. 8

a representation of the emergency closing valve energized in the closed position;

Fig. 9

a representation of a modified emergency shut-off valve with a return operation favoring the return spring and two mounted sensors for the two valve positions.

Production and operational readiness

The drive cylinder 1 of in FIG. 1 shown device is electrically disconnected in the basic position extended on the stop 6 and is pressed with the force of the emergency closing spring 16 against this. If the emergency drive is mounted on actuated elements, in particular valves, then the basic position is already present Reaching the stop 6. The force of the extended emergency closing spring 16 then acts z. B. on a mounted valve and ensures a safe closure (position in an emergency).

For the operational readiness of the emergency closing control, positioning and switching drive, the controlled seat valve 50 (emergency valve) must first be switched. During the entire operating time of this valve 50 must be in blocking position 52. Furthermore, the potential energy for an emergency closing process must be established. If the hydraulic pump 32 is conveyed through the cylinder space 5 and through the check valve 37 into the clamping cylinder space 12, the tensioning piston 11 moves as far as the piston stop 14 (FIG. Figur1 and 5 ). The emergency closing spring 16 is so tense. The clamping pressure can increase in height to the limit by the pressure limiting valve 33. The reaching of the end position can be signaled by a pressure sensor 64 or displacement sensor 60, 61 to monitor the position, or to initiate further control steps. The hydraulic pump 32 can remove the medium to be pumped through the check valve 34 from the spring chamber 13. The clamping piston 11 is locked by the check valves 36, 37 and the valve 50 in the blocking position 52. When tensioning the emergency closing spring 16, the drive axle 2 remains with the drive piston 3 and the driving piston 21 in the basic position ( FIG. 5 ). In the increasing volume of the driving chamber 23, the medium can flow through the volume flow-dependent 2-way valve 24.

Control and setting process

After reaching operational readiness, a control, setting or switching operation can be carried out ( FIG. 6 ). The position to be reached may be path, force or pressure or a signal from a mounted element. The direction of rotation and delivery rate of the hydraulic pump 32 determines the direction of movement and speed of the drive axle 2. The medium is respectively from the cylinder chambers 4 and 5 promoted back and forth ( FIG. 1 ). The respective pressure builds up according to the adjusting forces to be overcome. Due to temperature changes, compression or leakage possibly missing medium in the intake of the hydraulic pump 32 can be removed through the respective check valve 34 or 35 from the surge tank 31. Excess medium in cylinder chambers can flow through the check valves 36 or 37 via the pressure relief valve 33 in the surge tank 31, if it is not previously completely or partially possibly losses in the clamping cylinder space 12 fills

If the necessary pressures for the safe maintenance of the control position are not guaranteed, these can be controlled by the check valves 38, 39 and the pressure relief valves 42, 43 (FIG. FIG. 1 ) to reach. Direction of movement and speed of the drive shaft 2 are determined by the direction of rotation and flow rate of the hydraulic pump 32. Promoted medium in the cylinder chambers 4 or 5 with the result that medium flows from the respective other chamber via a check valve 36 or 37 in the clamping cylinder space 12 and there maintains the pressure to the limit by the pressure relief valve 33. As a result, the full voltage of the emergency closing spring 16 and the end position of the clamping piston 11 is constantly maintained. If the clamping piston 11 is already on the piston stop 14, then the medium flows via the respective pressure limiting valve 42, 43 to the suction side of the hydraulic pump 32. The difference of the pressures in the cylinder chambers 4 and 5 is decisive for the force generated on the drive axle 2 Movement of the drive, the pressure on the opposite side of the drive piston 3 must be overcome, the energy consumption is correspondingly higher. In each cylinder chamber 4, 5, however, there is at least the pressure equal to the set value of the pressure limiting valves 42 or 43, thus the drive piston 3 is constantly clamped. The position of the drive shaft 2 is thus maintained and the hydraulic pump 32 can be switched off. Depending on the application, this results in a considerable energy saving. The method is not only particularly suitable for setting and switching operations, also regulations with correspondingly large, permissible control deviations and suitable time courses can be operated in stages. The condition is that the set pressure of the pressure relief valve 33 is above the sum of the respective set pressure of the pressure relief valves 42 or 43 and the maximum necessary pressure for the cylinder chambers 4 or 5. Furthermore, with the set pressure of the pressure relief valves 42, 43, the maximum voltage of the emergency spring 16 must already be reached. Ie. the clamping piston 11 must rest on the piston stop 14.

emergency shutdown

An emergency shutdown always occurs when the seat valve 50 is turned off, that is, is de-energized and falls in passage position 51. The medium from the Spannzylinderraum 12, which is under pressure by the emergency-closing spring 16, flows directly into the spring chamber 13, which from the cylinder chamber 4 through the throttle 40 and the Check valve 36 and the check valves 35, 39 ( FIG. 3 ) in the cylinder chamber 5. volume differences by the extending drive axle 2, by temperature and pressure changes compensates the surge tank 31. Should the hydraulic pump 32 deliver during the emergency shutdown or after, it has no effect since the pumped medium can circulate without pressure in any direction. Is located between the driving piston 21 and the driving surface 15 of the clamping piston 11 is a distance ( FIG. 6 ), the driving chamber 23 is filled with medium. Immediately after triggering the emergency shutdown the emergency-closing spring 16 generates a rapid pressure increase in this and switches as a result, the volume flow-dependent 2-way valve 24 in blocking position 27. Between driving cylinder 22 and driving piston 21 is a defined gap through which the trapped volume of the driving chamber 23 throttled can drain off. The resulting pressure must be so great that the resulting force is greater than the maximum control or actuating force and the drive shaft 2 can not move against the Notschließrichtung. Through the throttle 40, the emergency closing speed can be determined.

The function of the drive can also be designed in the opposite direction (pulling). For this purpose, only the clamping cylinder 10 with the Notschließfeder and the driving cylinder 20 are arranged to be rotated 180 °.

The z. B. designed as a low-pressure accumulator reservoir 31 is used for volume compensation during movement of the drive axle 2, with volume changes by temperature response and compression in pressure changes. Another object is to maintain a pressure above atmospheric pressure within the hermetically sealed drive. Due to this overpressure, all static seals are constantly pushed outwards and thus are not subject to wear. Furthermore, the medium is protected from absorbing air. The only moving element between the interior of the drive and the atmosphere is the lead out of the drive axle 2.

The Z. B. designed as a controlled check valve seat valve 50 is designed so that when switching off the electrical holding current or power failure, the valve seat 53, 54 always opens ( FIG. 7 ). The valve cone 54 and thus also the magnet armature 56 are moved by the volume flow from P to R in the passage position 51. When the magnetic coil 55 is energized, the armature 56 is applied and presses the valve cone 54 in the valve seat 53. The valve 50 is thus closed ( FIG. 8 ). There the valve seat 53, 54 must be kept with a defined force and on the other hand, the electro-magnetic holding its largest holding force when planting the magnet armature 56 on the magnetic yoke 57, a spring compensation 58 is provided for a length compensation of the mechanical components. The spring force must be greater than the required closing force of the valve seat, but smaller than the securely applied electrical adhesion of the electromagnet. The resulting during Notschließvorgang by the emergency closing spring 16 media pressure must be so large at the terminal (P) that the existing after switching off the solenoid coil 55 residual force from the remanence in the magnetic yoke 57 and armature 56 is overcome. All components of the valve 50 are in the media area and are sealed to the atmosphere. If the passage position 51 of the disconnected valve 50 must be kept, this is the return spring 59 ( FIG. 9 ) intended.

The position sensor 61 signals the position of the clamping piston 11 and thus the operational readiness of the emergency closing spring 16. The position sensor 62 signals the position of the drive axle 2. The pressure transducer signalize the respective hydraulic pressures, for Spring chamber 13 and expansion tank 31 Pressure transducer 63, for clamping cylinder chamber 12 Thruster 64, for cylinder chamber retract 5 Thruster 65 and retract for cylinder chamber 4 Thruster 66. The position of the controlled seat valve 50 (emergency valve) is monitored by a displacement sensor or by position sensor ( FIG. 9 ). Position sensor 67 signals passage position 51 (basic position, valve open), position indicator 68 signals blocking position 52, valve closed.

If the dimensions of the emergency closing drive assume greater values, it is no longer possible or useful to design the drive axle 2 with the driving cylinder 20 and the emergency-tensioning cylinder 10 continuously and to produce them in the necessary close tolerances. For this purpose, a separation of the drive axle 2 by a clutch 7 ( FIG. 6 ), which allows a radial offset made. <B> LIST OF REFERENCES </ b> 1 drive cylinder 35 check valve 2 drive axle 36 check valve 3 drive piston 37 check valve 4 Retract cylinder space 38 check valve 5 Extend cylinder space 39 check valve 6 Extend the cylinder stop 40 throttle 7 clutch 42 Pressure relief valve 43 Pressure relief valve 10 clamping cylinder 11 clamping piston 50 Seat valve (emergency valve) 12 Clamping cylinder chamber 51 Through position 13 spring chamber 52 blocking position 14 piston stop 53 valve seat 15 drive surface 54 shuttle 16 Emergency closing spring 55 solenoid 56 armature 20 slave cylinders 57 yoke 21 slave piston 58 spring balancing 22 slave cylinders 59 Return spring 23 entrainment chamber 24 Volume flow dependent 2-way valve 60 encoder 25 throttle 61 locator 26 open position 62 locator 27 blocking position 63 thruster 64 thruster 31 surge tank 65 thruster 32 hydraulic pump 66 thruster 33 Pressure relief valve 67 locator 34 check valve 68 locator

Claims (15)

1. A hydraulic device having:

   - a motor, which is arranged in a motor housing,

   - a compensating tank (31) for accommodating hydraulic fluid,

   - a hydraulic pump (32), which is arranged in a pump housing and is driven by the motor,

   - an actuator to be hydraulically controlled or actuated,

   - wherein the hydraulic pump (32) is designed such that it allows hydraulic fluid to be delivered in two directions, namely in the forward and rearward directions, wherein

   - the hydraulic actuator comprises a drive cylinder (1) with a first (4) and a second (5) cylinder chamber and a drive piston (3), which is arranged between said chambers and to which is fitted a longitudinally displaceable drive axle (2), characterized in that

   - the device comprises a bracing cylinder (10) for an emergency closing spring (16),

   - the bracing cylinder has arranged in it a bracing-cylinder chamber (12) and a bracing piston (11), which can be coupled to the drive axle (2),

   - wherein the bracing piston (11) can brace the emergency closing spring (16) in a bracing or emergency triggering standby position,

   - wherein the bracing-cylinder chamber (12) is connected to an outlet of the hydraulic pump (32) such that, as a result of the hydraulic pressure of the hydraulic pump (32), the bracing-cylinder chamber (12) can be filled with hydraulic fluid, and the bracing piston (11) upon compression of the emergency closing spring (16) can be transferred into a bracing position and can be locked there hydraulically by check valves (36, 37),

   - and wherein a controlled seat valve (50) is connected to an inflow/outflow opening of the bracing-cylinder chamber (12),

   - said seat valve being capable of transferring the emergency closing spring (16) from the braced standby position into an emergency triggering open position,

   wherein it is possible both for hydraulic fluid which keeps the emergency closing spring (16) in the standby position, and is located in the bracing-cylinder chamber (12), and for the hydraulic fluid which is located in the first cylinder chamber (4) to be discharged via the controlled seat valve (50).
2. The hydraulic device according to claim 1, characterized in that an outlet (R) of the controlled seat valve (50) is connected to a spring chamber (13) of the bracing cylinder (10), said spring chamber containing the emergency triggering spring (16).
3. The hydraulic device according to one of the preceding claims, characterized in that the drive axle (2) and the drive piston (3) are coupled to the bracing piston (11) such that, when the bracing piston (11) is locked hydraulically in the standby position, the drive axle (2) and the drive piston (3) can be displaced linearly, in dependence on the pressure applied by the hydraulic pump (32), in the longitudinal direction of the drive axle (2) in order to execute a control/regulating and/or switching movement.
4. The hydraulic device according to one of the preceding claims, characterized in that the compensating tank (31) is connected to the outlet (R) of the controlled seat valve (50).
5. The hydraulic device according to one of the preceding claims, characterized in that hydraulic outlets of the first (4) and of the second (5) cylinder chambers of the drive cylinder (1) are connected to the bracing-cylinder chamber (12) via check valves (36, 37) so as to block a hydraulic flow from the bracing-cylinder chamber (12) into the first and second cylinder chambers (4, 5) of the drive cylinder (1).
6. The hydraulic device according to one of the preceding claims, characterized in that a hydraulic outlet of the bracing-cylinder chamber (12) is connected to the spring chamber (13) and/or the compensating tank (31) via a pressure-limiting valve (33).
7. The hydraulic device according to one of the preceding claims, characterized in that the controlled seat valve (50) includes a magnetically, electrically, mechanically, pneumatically or hydraulically controlled emergency triggering mechanism which transfers the seat valve (50) into a throughflow position.
8. The hydraulic device according to one of the preceding claims, characterized in that, in the region of the bracing cylinder (10), at least one displacement sensor (60) and/or at least one position sensor (61, 62) is/are arranged, which make it possible to detect a state of operational readiness and/or a position of the bracing piston (11) and/or of the drive piston (3).
9. The hydraulic device according to one of the preceding claims, characterized in that, in the region of the bracing cylinder (10), at least one pressure sensor (63, 64, 65, 66) is arranged, which makes it possible to detect hydraulic pressures for the spring chamber (13), bracing-cylinder chamber (12) and/or actuating-cylinder chambers (4, 5).
10. The hydraulic device according to one of the preceding claims, characterized in that, on the controlled seat valve (50), at least one displacement sensor or position sensor (67, 68) is arranged, which makes it possible to detect an open/closing position of the controlled seat valve (50).
11. The hydraulic device according to one of the preceding claims, characterized in that the drive axle (2) is configured in a number of parts and the parts of the drive axle (2) are connected via a coupling (7), which allows for a radial offset of the drive axle (2) and is arranged in the transition region between carry-along cylinder (20) and bracing cylinder (10).
12. The hydraulic device according to one of the preceding claims, characterized in that the drive axle (2) is coupled to the bracing piston (11) via a carry-along cylinder (20) with a carry-along piston (21) which is movable therein, wherein the carry-along piston (21) and the bracing piston (11) have arranged between them a hydraulic carry-along chamber (23), which is connected to the bracing-cylinder chamber (12) via a volume-flow-dependent two-way valve (24).
13. The hydraulic device according to claim 12, characterized in that the hydraulic volume trapped within the hydraulic carry-along chamber (23) can be discharged therefrom in a defined manner by a throttling action.
14. The hydraulic device according to one of the preceding claims, characterized in that an emergency closing valve is coupled to the drive axle (2) of the hydraulic actuating arrangement, wherein the emergency closing valve being a valve which can be regulated.
15. The hydraulic device according to one of the preceding claims, characterized in that an actuating or switching drive with an emergency switch-off function is coupled to the drive axle (2) of the hydraulic actuating arrangement.

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