EP2242933A1

EP2242933A1 - Soft start device for compressed air systems and method for operating a soft start device

Info

Publication number: EP2242933A1
Application number: EP08715786A
Authority: EP
Inventors: Peter Christiani; Günter Gebauer; Bodo Neef; Markus Kleske; Udo Walden
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 2008-02-15
Filing date: 2008-02-15
Publication date: 2010-10-27
Anticipated expiration: 2028-02-15
Also published as: CA2715222C; US8567442B2; CA2715222A1; US20110277843A1; EP2242933B1; WO2009100734A1

Abstract

The invention relates to a soft start device for compressed air systems having a primary inlet (P1) that can have compressed air fed thereto under primary pressure, wherein the primary inlet (P1) is connected to a secondary outlet (P2) that can be coupled to at least one consumer by means of a valve circuit that can have compressed air discharged therefrom under secondary pressure, wherein the secondary pressure is less than or equal to the primary pressure, wherein a main valve of type 2/2 (normally closed ) that can be bypassed by means of a bypass (17) is connected between the primary inlet (P1) and the secondary outlet (P2), wherein a throttle device (13) is connected in the bypass (17), wherein the main valve (WV5) and throttle device (13) and further valves (WV1, WV3, WV4, WV5, WV6) of the valve circuit are connected to each other, and the valve circuit can be set to a standard venting setting, such that the secondary outlet (P2) is vented, wherein the valves (WV1, WV3, WV4, WV5, WV6) of the valve circuit are connected to each other such that, in addition to the standard venting setting, a plurality of further venting settings are possible, wherein each of the further venting settings result when any arbitrary one of the existing valves (WV1, WV3, WV4, WV5, WV6) has a fault during the actuation process normally bringing about the standard venting setting.

Description

Soft-start device for compressed-air systems and method for operating a soft-start device

The invention relates to a soft start device for compressed air systems and to a method for operating a soft start device. The softstart device,

- with a primary inlet to which compressed air can be supplied under primary pressure,

- wherein the primary inlet is connected to a secondary outlet which can be coupled to at least one consumer via a valve circuit, to which compressed air at secondary pressure can be discharged, the secondary pressure being less than or equal to the primary pressure,

in which a main valve of the type 2/2 -nc (normally closed) is switched on between the primary inlet and the secondary outlet, which can be bypassed by means of a bypass, a throttle device being switched on in the bypass,

- Wherein the main valve and throttle device are interconnected together with further directional valves of the valve circuit such that at a soft start, initially locked main valve, compressed air with respect to the primary pressure lower, gradually increasing secondary pressure at the secondary outlet is applied, up to a certain Ratio between secondary and primary pressure a switching operation of the main valve takes place in its open position, so that then compressed air with primary pressure reaches the secondary outlet, and

- The valve circuit is set in such a standard venting switch position that the secondary outlet is vented.

Soft-start devices are used in compressed-air systems to supply compressed-air-sensitive functional units, such as, for example, service devices, etc., with compressed air, the pressure gradually increasing from a relatively low secondary pressure to the primary or operating pressure. As a result, pressure surges are avoided with high, harmful primary pressure. Pressure-impact-prone functional units are, for example, filter units or double-acting pneumatic cylinders. In the case of double-acting pneumatic cylinders, it may happen that the piston is in a "neutral" state of the cylinder in a central position, so that, if the full pressure shock acting on the piston, this could suddenly drive into one of the end positions, causing damage to the Piston or could lead to the end stop of the cylinder. Optionally, a subordinate functional unit is actuated unintentionally by the unwanted piston movement, which in turn can lead to dangerous situations. Dangerous movements can also lead to personal injury. This is prevented by the soft start, so that the piston moves relatively slowly to its end position.

A soft-start device is disclosed, for example, in EP 0 758 063 B1, in which a start valve in the form of a poppet valve is described, wherein the valve is vented via a quick exhaust. The start valve has a Housing in which a single, extending from the inlet to the outlet flow path is formed, wherein in the flow path acting as a throttle seat valve is arranged.

In compressed air systems, certain safety aspects must be taken into account. These are categorized, for example, in the standard EN 954-1 and in the subsequent standard DIN EN ISO 13849-1. In order to comply with category 3 of the EN 954-1 standard, it is required that the compressed air device has a so-called "one-fault safety" for safety-relevant functions. This means that, despite a single fault in the system, bleeding must be possible.

A soft-start device of the type mentioned in the introduction, which offers "one-fault safety", is disclosed in EP 1 645 755 A2, whereby the secondary outlet can nevertheless be vented in the event of malfunction of one of the valves, thus satisfying the requirements of standard EN 954-1, category 3.

However, in the subsequent standard DIN ISO 19849 for category 3 and in particular for category 4, a higher test quality is required, in particular that a test or diagnostic mode of the valves can be carried out prior to the soft start procedure in order to rule out errors when initiating the softstart process.

The object of the invention is therefore to provide a soft start device or a method for operating a soft start device of the type mentioned above, with or with the prior to the initiation of the startup process, a diagnostic mode is feasible. This object is achieved by a soft start device having the features of independent claim 1. Further developments of the invention are shown in the subclaims.

The soft-start device according to the invention is characterized in that

the inlet of the main valve designed as the fifth directional control valve of the type 2/2 -nc is connected to the primary inlet and the outlet is connected to the inlet of a fourth directional valve of the type 3/2 nc and, in parallel thereto, to the outlet of the throttle device fifth directional control valve is coupled to the output of the throttle device and in addition to an outlet of a sixth directional control valve of the type 4/2 -nc,

the inlet of the first directional control valve of type 3/2 -nc is connected to the primary inlet and the outlet is connected to the control side of the sixth directional valve, the first directional control valve being able to be vented via a venting outlet and being actively switchable via switching means arranged on the control side,

the inlet of the third directional control valve of the type 3/2 -nc is coupled to the primary inlet and the outlet of the third directional control valve is coupled to the control side of a fourth directional control valve of the type 3/2-nc, the third directional control valve being able to be vented via a venting outlet and arranged via the control side Switching means is actively switchable,

- The outlet of the fourth directional valve is connected to the secondary outlet and parallel thereto with an inlet of the sixth directional valve, wherein the fourth directional valve is vented via a vent outlet, and - The sixth directional control valve between a normal position and a functional position is switchable, wherein in the normal position, a first inlet connected to the secondary outlet and parallel to the outlet of the fourth directional valve 5, while the associated first vent outlet is open to the atmosphere, and a second inlet is coupled to the control side of the fifth-way valve, while an associated second vent outlet is open to the atmosphere, and wherein in the operative position, the inlet lo is connected to the outlet of the fourth directional valve and parallel to the secondary outlet and the associated outlet to the control side of the fifth Directional valve is coupled.

First and third directional control valves are thus connected in parallel, wherein the first directional control valve controls the sixth directional control valve and the third directional control valve activates the fourth directional control valve. This makes it possible to drive a test or diagnostic mode in which the switching states of the fourth and sixth directional control valves are checked independently of one another. Since the fourth and sixth directional control valves can not be actively switched, it is advantageous that the switching states of these valves can be checked before initiating the softstart process. In particular, after long periods of inactivity, these valves could, for example, form a so-called "slip-stick" effect, whereby these valves do not switch into their open or functional position as intended despite compressed air being applied to their control side The diagnostic mode ensures that there is no malfunction of one of the valves during the softstart operation.

In a particularly preferred manner, the non-actively switchable directional valves by adjusting springs and additionally by Pressurized with compressed air, held in its nc position to achieve pre-pressure independence. Alternatively, it would also be possible to keep the relevant directional valves in their nc position without additional pressurization and to use, for example, a spring with correspondingly greater spring force.

It is possible for the throttle device to have an adjustable throttle valve and, in addition, a fixed throttle in the form of a throttle bypass which bypasses the adjustable throttle. This prevents the flow path is completely shut off when fully closing the throttle valve.

In a particularly preferred manner, a sensor device with a plurality of sensors for determining the current Schaltzu- states of the valves, in particular the non-actively switchable directional valves, provided. The sensors can be designed, for example, as a reed switch. However, other sensor types can also be used. Expediently, a control device coupled to the switching means of the first and third directional valve is provided. Characterized a signal transmission from the sensors to the control device and in dependence of an evaluation result of the control device to the switching means is possible.

The invention further comprises a method for operating a soft start device having the features of independent claim 11.

The method according to the invention, with which a test or diagnostic mode can be run, has the following method steps: Switching the first directional valve to its open position, whereby the control side of the sixth directional valve is supplied with compressed air,

Determination of the switching state of the sixth directional valve by means of the associated sensor,

- determining the result of the switching state query, wherein in a detected switching operation of the sixth-way valve, a switching operation of the third-way valve or the soft-start process is initiated,

Switching the third directional control valve to its open position or, alternatively, before switching the first directional control valve, wherein the first directional control valve is in its nc position when the third directional control valve is switched, the control side of the fourth directional control valve being pressurized by switching the third directional control valve is charged

Determination of the switching state of the fourth directional valve by means of the associated sensor,

- Determining the result of the switching state query, wherein in a detected switching operation of the fourth directional valve, a switching operation of the first directional control valve or the soft start process is initiated.

As already mentioned, first and third directional control valves are connected in parallel, whereby the sixth directional control valve can be pressurized independently of the fourth directional control valve. Appropriately, there is first a switching of the first directional control valve, with the result that the control side of the sixth directional valve is subjected to compressed air. The switching state of the sixth-way valve is then by means of the sensor checked. If a shift has taken place, the train between the primary inlet, the first directional control valve and the sixth directional control valve is faultless and, next, a diagnosis of the other strand containing the third and the fourth directional control valve can be carried out. In this case, the first directional valve is again in its nc position. If a switching operation of the fourth directional valve is detected even when the third directional control valve is switched on, then this sequence is also faultless. This will then initiate the softstart process. Of course, it is also possible first to test the third directional control valve and the third directional control valve with the fourth directional control valve and then the first directional control valve and the first directional control valve with the sixth directional control valve.

In a further development of the invention, a signal transmission corresponding to the result of the switching state inquiry takes place from the relevant sensor to the control device, with activation or no activation of the switching means associated with the first and third directional valve taking place depending on the result. If no error is detected, the soft start process can be initiated automatically. However, if an error is detected in one of the strands, the initiation of the softstart process is omitted.

A preferred embodiment of the invention is illustrated in the drawing and will be explained in more detail below. The drawing shows:

1 shows a valve circuit including pressurized strands (bold lines) of a preferred embodiment of the soft-start device according to the invention in the rest position before the soft-start process, 2 shows the valve circuit according to FIG. 1 in the diagnostic mode when the first directional control valve is switched, FIG.

3 shows the valve circuit according to FIG. 1 in the diagnostic mode when the third directional control valve is switched, while the first directional control valve is in its nc position, FIG.

1 with switched first and third directional valve, wherein here the soft start process is initiated,

5 shows the valve circuit according to FIG. 1 after the soft start process, FIG.

6 shows the valve circuit according to FIG. 1 during the venting process in standard venting switching position, FIG.

FIG. 7 shows the valve circuit according to FIG. 1 during the venting process, the first directional control valve having a malfunction, FIG.

FIG. 8 shows the valve circuit according to FIG. 1 during the venting process, wherein the third directional control valve malfunctions, FIG.

9 shows the valve circuit according to FIG. 1 during the venting process, the fifth directional control valve malfunctioning, FIG.

10 shows the valve circuit of FIG. 1 during the venting process, wherein the fourth directional control valve has a malfunction, and 11 shows the valve circuit according to FIG. 1 during the venting process, wherein the sixth directional valve has a malfunction.

1 to 11 show a preferred embodiment of the soft start device 11 according to the invention. The components of the valve circuit can be housed together in a valve unit here. It is a primary inlet Pl provided, is supplied to the compressed air under primary pressure. The primary inlet Pl is connected via a main flow path 12 to a secondary outlet P2, on which in turn compressed air is discharged under secondary pressure to the consumers.

For example, as shown in FIG. 1, the valve circuit according to the preferred embodiment is constructed as follows:

A fifth directional valve WV5 of the type 2/2 -nc is provided, whose inlet E5 with the primary inlet Pl and its outlet A5 is connected to the inlet E4 of a fourth directional valve WV4 of the type 3/2-nc and in parallel therewith with the outlet of a throttle valve. direction is connected 13, wherein the fifth-way valve WV5 is the control side coupled to the output of the throttle device 13 and in addition to an outlet A6 of a sixth directional valve WV6 type 4/2 -nc, if the sixth directional valve WV6 in its operating position described below located. The fifth directional control valve WV5 is held in its NC position via a control spring 14 and additionally by means of compressed air supply by coupling to the primary inlet P1. Furthermore, the fifth directional control valve WV5 is assigned a sensor for determining its current switching state. In parallel connection to the fifth directional control valve WV5, a first directional valve WVl is arranged, the inlet El of which is connected to the primary inlet Pl and its outlet Al is connected to the control side S6 of a sixth directional valve WV6, wherein the first directional valve WVl can be vented via a vent outlet Rl and via control means arranged on the control side 16 is active switchable. Furthermore, the first directional valve WVl is held in its nc position via a restoring spring 14.

A third directional valve WV3 is arranged parallel to the first directional valve WV1, whose inlet E3 is coupled to the primary inlet P1 and its outlet A3 is connected to the control side S4 of a fourth directional valve WV4 of the type 3/2 -nc, the third directional valve WV3 being connected via a venting outlet R3 can be vented and via switching means arranged switching means 16 is actively switched.

The fourth directional valve WV4 controlled by means of the third directional valve WV3 is connected via its outlet A4 to the secondary outlet P2 and parallel to an inlet E6 of a sixth directional valve WV6, wherein the fourth directional valve WV4 can be vented via a venting outlet R4. The fourth directional control valve WV4 is held in its nc position by means of a control spring 14 and additionally by means of compressed air injection by means of coupling to the outlet of the throttle device 13 and, in parallel thereto, by coupling to the output A5 of the fifth directional valve WV5. In addition, there is a sensor 15 for

Determining the current switching state of the fourth directional valve WV4 provided.

Finally, the sixth directional control valve WV6 controlled by means of the first directional control valve WV1 is switchable between a normal position and a functional position, with a first inlet E6 in the normal position with the secondary outlet P2 and is connected in parallel to the outlet A4 of the fourth directional valve WV4, while the associated first vent outlet R6 is open to the atmosphere. In the normal position of the sixth directional valve WV6, a second inlet E6 * is further coupled to the control side S5 of the fifth directional valve WV5, while a corresponding second venting outlet R6 * is open to the atmosphere. By contrast, in the functional position of the sixth directional valve WV6, its inlet E6 is connected to the outlet A4 of the fourth directional valve WV4 and parallel to the secondary outlet P2, while the associated outlet A6 is coupled to the control side S5 of the fifth directional valve WV5.

In Fig. 1, a switching position is shown in which all 3/2 or 2/2 way valves are in their nc position, and the sixth directional valve WV6 type 4/2 -nc in its normal position. This position could also be referred to as a rest position before the soft start process. In this case, compressed air having primary pressure P 1 originating from the primary inlet P 1 is present at the inlet E 1 of the closed first directional valve WV 1, parallel to this at the inlet E 5 of the closed fifth directional valve WV 5, and parallel thereto at the inlet E 3 of the third directional valve WV 3. In parallel with this, compressed air for supporting the adjusting spring 14 reaches the counter-control side of the fifth directional valve WV5. Finally, compressed air flows into the bypass 17 and there reaches the throttle device 13 and from there to the inlet E4 of the closed fourth directional valve WV4, to the outlet A5 of the closed fifth directional valve WV5 and to the control side S5 of the fifth directional valve WV5. An adjustable throttle valve is provided here as throttle device 13, and an additional fixed throttle in the form of a throttle bypass which bypasses the adjustable throttle. This prevents the flow path from being completely blocked when the throttle valve is closed. is closing. Rather, a quantity of compressed air via the throttle bypass, which has a relatively small cross section, can always reach the associated ports of the fourth and fifth directional valve WV4 and WV5. Finally, the compressed air with primary pressure is still at the counter-control side of the fourth directional valve WV4 and thus supports the actuating force of the spring 14th

2 shows a test mode in which initially only the first directional control valve WV1 has switched into its open position so that compressed air and the primary pressure reach the control side S6 of the sixth directional control valve WV6. In the test or diagnostic mode, a switching state inquiry of this sixth directional valve WV6 is carried out by means of the sensor 15 assigned to the sixth directional valve WV6. The sensor 15 thus detects the switching state of the sixth directional valve WV6 and transmits with this corresponding signals to a control device 20. If the sixth directional valve WV6 switched to its functional position, as shown in Fig. 2, it can be ruled out that the sixth directional valve WV6 a Malfunction has. This could be the case, for example, in the case of prolonged downtimes, for example due to the aforementioned "slip-stick effect." In a switching operation of the sixth directional valve WV6, the line primary inlet P1, first directional valve WV1 and sixth directional valve WV6 are free of errors 20, the first directional control valve WV1 is now switched back to its nc position, but if it is detected that the sixth directional control valve WV6 has not switched to its functional position in accordance with the regulations, an abort occurs here, ie a continuation of the process is no longer possible until the error is fixed.

FIG. 3 also shows the test mode in which, after it has been determined that the strand primary outlet, first Directional valve WVl and sixth directional valve WV6 has no error, the third directional valve WV3 is switched to the open position. The third directional valve WV3 is switched to its open position so that compressed air and the primary pressure reach the control side S4 of the fourth directional valve WV4. Here, too, a switching state query of the fourth directional valve WV4 is carried out by means of the associated sensor 15. The signals corresponding to this switching state are in turn transmitted to the control device 20. If the fourth directional valve WV4 has switched to its open position shown in FIG. 3 in accordance with regulations, then the primary inlet P1, the third directional valve WV3 and the fourth directional valve WV4 are faultless. If, on the other hand, it is detected that the fourth directional control valve WV4 has not switched to the open position in accordance with the regulations, an abort also occurs here, ie the process is aborted until the fault has been rectified. In the event that the fourth directional control valve WV4 has switched to the open position in accordance with the regulations and the sensor 15 has transmitted the signals corresponding thereto via the detected switching state to the control device 20, the control device 20 activates the switching means 16 assigned to the first directional valve WV1, whereby automatically the soft start process shown in FIG. 4 is initiated.

Fig. 4 shows, as mentioned, a switching position when initiating the soft start process. In this case, the first directional valve WVl and the third directional valve WV3 have switched to the correct position in their open position. Although in the locked state of the fourth directional valve WV4 upstream of its input E4, compressed air has accumulated under primary pressure, this compressed air quantity initially blocked between the outlet of the throttle device 13 and the input E4 of the fourth directional valve WV4 is discharged when the fourth directional valve WV4 is opened and gets to Primary outlet P2. Compressed air under primary pressure, however, can not flow immediately because the throttle device 13 is interposed, which throttles the upcoming compressed air under primary pressure to Sekunkärdruck. Thus, compressed air with secondary pressure reaches the fourth directional valve WV4 and there to the primary outlet P2. At the same time, compressed air flows under secondary pressure to the inlet E6 of the sixth directional valve WV6 and arrives there via the outlet A6 to the control side S5 of the fifth directional valve WV5. At the same time, there is a direct connection from the outlet of the throttle device 13 to the control side S5 of the fifth directional valve WV5, so that the fifth directional control valve WV5 is subjected to double compressed air and the secondary pressure to the control side. The pressure at the secondary outlet P2 now rises again gradually until, after a certain ratio between secondary and primary pressure, a switching of the fifth directional valve WV5 into its open position is initiated. The ratio between secondary and primary pressure may be, for example, in the range of> 0 to 1, in particular 0.4 to 0.6. It is particularly preferred to switch to the open position if the secondary pressure P2 is equal to approximately 0.5 primary pressure P1.

Fig. 5 shows the switching position after the SoftStartvorgang. By the upcoming pressure on the control side S5 of the fifth directional valve WV5 this has opened, so that compressed air passes directly from the primary inlet Pl via the main flow path 12, the fourth directional valve WV4 passing to the secondary outlet P2 and from there to the consumers.

Fig. 6 shows a standard venting switch position for venting the secondary outlet P2. The first and third directional valve WVl and WV3 have to be correctly incorporated in their nc

Switched back position so that the pending on the control side S4 of the fourth directional valve WV4 compressed air on the Vent outlet R3 escapes, while escaping at the control side S6 of the sixth directional valve WV6 compressed air escapes through the vent outlet Rl. As a result, the fourth directional control valve WV4 has switched back to an nc position, while the sixth directional control valve WV6 has returned to its normal position. Compressed air coming from the secondary outlet P2 can now escape via the vent outlet R4 of the fourth directional valve WV4 and additionally via the vent outlet R6 of the sixth directional valve WV6. The vent outlets R4 and R6 are preferably combined to form a common central vent outlet 18 which is open to the atmosphere. The central vent outlet 18 may also be associated with a muffler 19 for sound attenuation of the rotating compressed air.

If the soft start operation is aborted and is to be vented, the default bleed switch position will be set, i. Compressed air coming from the secondary outlet P2 escapes via the exhaust outlets R4 and R6 of the fourth and sixth directional valves WV4 and WV6.

Fig. 7 shows a venting switching position, in which the first directional valve WVl has a malfunction, that has not switched back to its nc position. As a result, the passage El-Al remains open and compressed air still remains on the control side S6 of the sixth directional valve WV6, so that it remains in its functional position. The vent outlet R6 of the sixth directional valve WV6 is thus blocked. However, venting is still possible because the third directional control valve WV3 has switched back to its nc position in accordance with regulations, so that compressed air present on the control side S4 of the fourth directional valve WV4 can escape via the venting outlet R3, whereby the fourth directional valve WV4 moves into its nc Position switches back. From secondary outlet P2 Compressed air can now escape into the vent outlet R4. In addition, the control side S5 of the fifth-way valve WV5 is vented via the ports A6-E6 and the vent outlet R4, so that the fifth-way valve WV5 returns to its nc position.

Fig. 8 shows a venting switch position in which the third directional valve WV3 malfunctions, i. did not switch back to its nc position. As a result, the passage E3-A3 remains open and compressed air is still at the control side S4 of the fourth directional valve WV4, so that this remains in its open position. The vent outlet R4 of the fourth directional valve WV4 is thus blocked. However, venting is still possible because the first directional control valve WVl has switched back to its nc-position, so that at the control side S6 of the sixth directional control valve WV6 upcoming compressed air can escape through the vent outlet Rl, whereby the sixth directional valve WV6 switches back to its normal position. Compressed air coming from the secondary outlet P2 can now escape via the vent outlet R6. In addition, the control side S5 of the fifth directional valve WV5 is vented to the atmosphere via the ports A6-E6, so that the fifth directional control valve WV5 returns to its nc position.

9 shows a venting switching position in which the fifth directional control valve WV5 has a malfunction, that is, has not switched back to its nc position. As a result, the main flow path 12 remains open via E5-A5, so that compressed air originating from the primary inlet P1 can flow in. However, venting is still possible because the two-way valves WVl and WV3 have switched back to their nc positions, whereby both the control side S4 of the fourth directional valve WV4 and the control side S6 of the sixth directional valve WV6 vented be so that fourth and sixth directional valve WV4 and WV6 have switched back to their nc position or normal position. This in turn makes it possible to vent the compressed air coming from the secondary outlet P2 via the vent outlets R4 and R6.

Fig. 10 shows a venting switch position in which the fourth directional valve WV4 malfunctions, i. did not switch back to its nc position. The vent outlet R4 is thus blocked. Bleeding is still possible because first and third directional valve WVl and WV3 have switched back to their nc positions in accordance with regulations, whereby in particular the control side S6 of the sixth directional valve WV6 is vented, so that this switches back to its normal position, so that at the control side S5 of the fifth directional valve WV5 is vented via the connections E6 * and R6 *, so that the fifth directional valve WV5 also switches back to its nc position. Compressed air coming from the secondary outlet P2 can now escape via the vent outlet R6.

Finally, Fig. 11 shows a bleed switching position where the sixth directional valve WV6 malfunctions, i. has not returned to its normal position. As a result, the vent outlet R6 is blocked. First and third directional valves WV1 and WV3, however, have switched back to their nc position in accordance with regulations, so that the control side S4 of the fourth directional valve WV4 is vented, as a result of which it switches back into its nc position, so that the compressed air originating from the secondary outlet P2 escapes via the venting outlet R4 can. In addition, the control side S5 is vented via the connections A6-E6 and the exhaust outlet R4, so that the fifth directional valve WV5 switches back to its nc position.

Claims

claims

1. Softstart device for compressed air systems,

with a primary inlet (Pl) to which compressed air can be supplied under primary pressure,

5 - wherein the primary inlet (Pl) is connected to a secondary outlet (P2) which can be coupled to at least one consumer via a valve circuit on which compressed air can be discharged under secondary pressure, the secondary pressure being less than or equal to the primary pressure,

lo - wherein between the primary inlet (Pl) and secondary outlet (P2), a main valve (WV5) of the type 2/2-nc (normally closed) is turned on, by means of a bypass (17) is bypassed, wherein in the bypass (17) has a throttle device (13) is switched on,

i5 - wherein the main valve (WV5) and throttle device (13) together with other directional control valves (WVl, WV3, WV4, WV6) of the valve circuit are interconnected such that at a startup, initially locked main valve (WV5), compressed air with respect to the primary -

Pressure is applied to the secondary outlet (P2) at a lower, gradually rising secondary pressure until, at a certain ratio between secondary and primary pressure, a switching Process of the main valve (WV5) takes place in its open position, so that then compressed air with primary pressure to the secondary outlet (P2) passes and

the valve circuit in such a standard

5. vent switch position is displaceable, that the secondary outlet (P2) is vented,

characterized in that

the inlet (E5) of the main valve designed as the fifth directional control valve (WV5) of the type 2/2-nc with the primary inlet (P1) and the outlet (A5) with the inlet (E4) of a fourth directional valve (WV4) of Type 3/2 -nc and connected in parallel with the output of the throttle device (13), wherein the fifth directional control valve (WV5) control with the output of the Drosseleinrich- device (13) and additionally with an outlet (A6) of a sixth-way valve (WV6) of type 4/2 -nc is coupled,

the inlet (El) of the first directional valve (WVl) of the type 3/2 -nc with the primary inlet (Pl) and the outlet (Al)

20 with the control side (S6) of the sixth-way valve

(WV6) are connected, wherein the first directional control valve (WVl) via a vent outlet (Rl) can be vented and via control side switching means (16) is actively switched, 5 - the inlet (E3) of the third directional valve (WV3) of the type 3/2 -nc with the primary inlet (Pl) and the outlet (A3) of the third directional valve (WV3) are coupled to the control side (S4) of a fourth directional valve (WV4) of the type 3/2 -nc, the third directional valve (WV3) via egg- venting port (R3) can be vented and can be actively switched via control means (16) arranged on the control side,

- The outlet (A4) of the fourth directional valve (WV4) with the secondary outlet (P2) and in parallel with an inlet (E6) of the sixth directional valve (WV6) is connected, wherein the fourth directional control valve (WV4) via a vent outlet (R4 ) is ventable, and

- The sixth directional control valve (WV6) is switchable between a normal position and a functional position, wherein in the normal position, a first inlet (E6) to the secondary outlet (P2) and parallel to the outlet (A4) of the fourth directional valve (WV4) is connected while the associated first vent outlet (R6) is open to the atmosphere, and a second

Inlet (E6 *) is coupled to the control side (S5) of the fifth directional valve (WV5) while an associated second vent outlet (R6 *) is open to the atmosphere, and wherein in the operative position the inlet (E6) communicates with the outlet (A4) of the fourth directional valve

(WV4) and in parallel with the secondary outlet (P2) is connected and the associated outlet (A6) to the control side (S5) of the fifth-way valve (WV5) is coupled.

2. soft start device according to claim 1, characterized in that the vent outlets (R4, R6) of the fourth and sixth directional valve are combined to form a common, open to the atmosphere central vent outlet (18).

3. Soft start device according to claim 1 or 2, characterized in that the central vent outlet (18) is associated with a silencer (19) for sound attenuation of the exiting compressed air.

5 soft start device according to any one of the preceding claims, characterized in that the fifth directional control valve (WV5) by a spring (14) and additionally by pressurized air by means of coupling with the primary inlet (Pl) is held in its nc-position, and that the fourth lo directional valve (WV4) by a spring (14) and additionally by compressed air by means of coupling with the outlet (A5) of the fifth-way valve and held parallel to the output of the throttle device in its nc-position, and that the sixth directional control valve ( WV6) is held in its normal position by a setting spring (14) and additionally by compressed air admission by means of coupling with the secondary outlet (P2) and parallel to it with the outlet (A4) of the fourth directional valve (WV4).

5. Soft-start device according to one of the preceding An och pro claims, characterized in that the throttle device (13) has an adjustable throttle valve and in addition a fixed throttle in the form of an adjustable throttle bypass throttle.

6. soft start device according to one of the preceding An-5 claims, characterized in that the ratio between secondary and primary pressure above which a switching operation of the main valve (WV5) takes place in the open position, in the range of> 0 to 1, typically 0.4 to 0.6.

7. Soft start device according to one of the preceding An-o claims, characterized in that a sensor device is provided with a plurality of sensors (15) for determining the current switching states of the directional control valves, in particular the non-actively switchable directional control valves.

8. Soft start device according to claim 7, characterized marked 5 net, that the sensors are designed as reed switch.

9. Soft-start device according to one of the preceding claims, characterized in that a control device (20) coupled to the switching center of the first and third directional control valves (WV1, WV3) is provided.

lo

10. A method for operating a soft-start device according to one of claims 1 to 9, the method comprising the following steps:

Switching the first directional valve (WVl) to its open position, whereby the control side (S6) of the sixth directional valve i5 (WV6) is supplied with compressed air,

Determination of the switching state of the sixth directional valve (WV6) by means of the associated sensor (15),

- Determining the result of the switching state query, wherein at a detected switching operation of the sixth We- 0 geventils (WV6) a switching operation of the third directional valve (WV3) or the soft start process is initiated,

Switching of the third directional control valve (WV3) to its open position or alternatively before switching of the first directional control valve (WV1), the first directional control valve (WV1) being switched in its nc when the third directional control valve (WV3) is switched

Position, whereby the switching of the third way Tils (WV3) the control side (S4) of the fourth directional valve (WV4) is supplied with compressed air,

Determination of the switching state of the fourth directional valve (WV4) by means of the associated sensor (15),

5 - determining the result of the switching state query, wherein in a detected switching operation of the fourth directional control valve (WV4) a switching operation of the first directional control valve (WVl) or the soft start process is initiated,

11. The method according to claim 10, characterized in that lo takes place with the result of the switching state query signal transmission from the relevant sensor (15) to the control device (20) and depending on the switching state result, an activation or no activation of the first and third Directional valve (WVl, WV3) to i5 ordered switching means (16) takes place.