EP4211355B1 - Gas-powered drive system and operating method - Google Patents

Description

The invention relates to a gas-operated drive system, comprising a drive with a first chamber and a second chamber, which are separated from each other by a movable working element of the drive, in particular by a piston, an exhaust air throttle and a control valve,
wherein one chamber of the two chambers can be connected to a gas source to form a chamber that drives the working element, and the other chamber of the two chambers can be connected to a gas sink via the exhaust air throttle to form a chamber that counteracts the movement of the working element, in particular by means of a changeover valve. Preferably, the gas escaping through the exhaust air throttle also flows through a check valve that opens in the direction of the gas sink. This has the advantage that the gas cannot/does not have to flow through the exhaust air throttle for a return stroke of the working element, but can be guided past the exhaust air throttle in parallel, in particular bypassing the exhaust air throttle, if necessary through other system components.

The invention further relates to a method for operating a gas-operated drive system, comprising a drive with a first chamber and a second chamber, which are separated from one another by a movable working element of the drive, in particular by a piston, wherein one chamber of the two chambers is connected to a gas source to form a chamber driving the working element and the other chamber of the two chambers is simultaneously connected to a gas sink via an exhaust air throttle, in particular by means of a changeover valve, to form a chamber counteracting the movement of the working element.

Drive systems and methods of this kind are generally known in the art. For example, the EN 10 2009 001 150 A1 general throttling of pneumatic cylinders. Another gas-powered drive system is from the FR 2 738 040 A1 known.

Typical drives of such a system are, for example, cylinder-piston units, in which the piston is arranged as a working element between the chambers and can be subjected to gas pressure on both sides from the direction of each of the two chambers.

For example, ordinary air can be used as the gas, but the invention is not limited to this.

The usual way of working is that pressurized gas is fed from a pressure source that provides gas at a pressure greater than the surrounding atmospheric pressure, e.g. a compressor, into one of the chambers, whereby a force is exerted on the working element that moves the working element. This chamber thus forms a driving chamber. The movement displaces gas from the other chamber. The gas pressure prevailing there exerts a force on the working element that counteracts the movement. This chamber, from which gas is displaced when the working element moves, forms the counteracting chamber. The size of the counteracting force can be influenced by throttling the gas flow from the counteracting chamber in the direction of a gas sink, e.g. simply the environment, by means of an exhaust air throttle. For the purposes of the invention, the exhaust air throttle is referred to as such, even if air is not used as the gas, since this term has become established in the relevant terminology.

Preferably, in the prior art and also in the invention, the exhaust air throttle is set in such a way, in particular with regard to the pressure falling across the exhaust air throttle, that a so-called supercritical flow of the gas through the exhaust air throttle results. For example, this can usually be achieved if the inlet-side pressure before the exhaust air throttle is at least 2 times greater is the pressure on the outlet side after the exhaust air throttle. The pressures mentioned here and below are absolute pressures.

In supercritical flow, the flow velocity reaches the speed of sound, which has the advantage that the speed of the working element, e.g. the piston in a pneumatic cylinder, is independent of the load in the quasi-stationary state. The invention can also provide a subcritical flow in which the speed of sound is not reached.

The problem with this mode of operation is that it is energetically unfavorable because the driving chamber is always placed under maximum gas pressure. In principle, it is also known to throttle the inflow of gas into the driving chamber as an alternative to exhaust air throttling. Although this connection, known as supply air throttling, is more energetically favorable, the speed of the working element in the drive is not load-independent in such a case, since even with a supercritical flow through the supply air throttle, the inflowing gas mass flow is load-independent at a constant supply pressure, but due to the load-dependent gas density in the drive chamber, the constant mass flow leads to a load-dependent speed of the working element in the drive.

The object of the invention is to develop a system and a method of the type mentioned at the outset in such a way that an energetically more favorable mode of operation of an exhaust air throttled system can be achieved, preferably while further achieving a supercritical flow in the exhaust air throttle in order to obtain a preferred load-independent movement of the working element.

This task is solved in the system by the fact that the driving chamber is assigned the control valve through which the driving chamber can be filled with gas from the gas source, whereby the opening cross-section of the control valve can be adjusted depending on a control pressure prevailing in the flow direction in front of the exhaust air throttle or falling above the exhaust air throttle, whereby the opening cross-section can be increased with the control valve. is when a first limit pressure is undercut with falling control pressure and the opening cross-section can be reduced, in particular the control valve can be closed when a second limit pressure is undercut with further falling control pressure.

In the method, the object is achieved in that a control valve is assigned to the driving chamber, through which the driving chamber is filled with gas from the gas source, wherein the opening cross section of the control valve is adjusted depending on a control pressure prevailing in the flow direction upstream of the exhaust air throttle or falling above the exhaust air throttle, that the opening cross section is increased with the control valve when the falling control pressure falls below a first limit pressure and the opening cross section is reduced, in particular the control valve is closed when the further falling control pressure falls below a second limit pressure.

The invention can preferably provide that when a control pressure is present which is greater than the first limit pressure, the control valve is initially closed, i.e. only opens when the first limit pressure is undershot and increases the opening cross-section as the control pressure continues to fall.

It can also preferably be provided that as the control pressure continues to fall, the maximum opening cross-section between the two limit pressures is reached, but at the latest when the second limit pressure is reached. As the control pressure continues to fall, the opening cross-section of the control valve is reduced from the moment the second limit pressure is undershot, in particular until the control valve closes at a third limit pressure. It can also be provided that when the first limit pressure is present, the control valve is already partially open and does not close completely even if the control pressure is increased further.

In all designs, it can preferably be provided that in the range between the first and second limit pressure, the control valve increases the opening cross-section with decreasing control pressure and with increasing control pressure reduced. Likewise, in all designs it can preferably be provided that in the range between the second and third limit pressure the control valve reduces the opening cross-section with falling control pressure and increases it with increasing control pressure.

The respective change in the opening cross-section depends on the change in the control pressure, and in particular on its sign. This dependency can be linear, but does not have to be. A non-linear dependency between the change in control pressure and the change in the opening cross-section can also be provided.

Preferably, a check valve that opens in the direction of the driving chamber is located in series with the control valve in the flow path of the gas. Alternatively, a check valve that blocks in the direction of the driving chamber is located parallel to the control valve. The gas thus flows into the chamber through the control valve, whereas a return flow, e.g. during a return stroke of the working element, bypasses the control valve, especially if the latter is closed by its switching position in the return stroke.

The advantage of the invention is that a first limit pressure can be selected which ensures that the exhaust air throttle is operated with a desired differential pressure level across the exhaust air throttle. If the limit pressure is undershot, the control valve opens and more gas can flow into the driving chamber to achieve the desired pressure condition. In this way, regulation to the desired pressure level can be achieved.

By further taking into account a second limit pressure, which is below the first limit pressure, it can be taken into account that at the end of the possible stroke of a working element, the pressure in the counteracting chamber continues to fall, in particular it could not be increased by further opening of the control valve, so that the invention provides for reducing the opening cross-section, preferably closing the control valve completely. In particular, the standstill of the working element can thus at the end of the stroke is the triggering event for closing the control valve. The working element is thus separated from the pressure source.

If the drive, in particular the cylinder, works against a relatively low external load and consequently a small pressure difference at the working element is sufficient to perform the task, the driving chamber, in contrast to conventional exhaust air throttled systems, is not brought completely to the supply pressure of the system, but is only filled with the amount of air that leads to a pressure that is slightly higher than the pressure necessary to perform the task while maintaining a supercritical flow at the exhaust air throttle.

A return stroke of the working element is made possible, for example, particularly after switching by means of a switching valve, by supplying gas, preferably bypassing the exhaust air throttle, into the previously counteracting and now driving chamber, whereby in the return stroke the gas is led from the previously driving and now counteracting chamber past the closed control valve, e.g. through a check valve that opens in the return stroke. The gas flow in the return stroke can take place, for example, through a pressure control valve, in particular a pressure reducer, which is parallel to the exhaust air throttle in terms of flow, e.g. still in series with a check valve that opens in the direction of the chamber.

When the third limit pressure in the chamber currently to be filled is exceeded, the control valve is returned to an at least partially open position so that a new working stroke of the working element can be carried out, in particular by adjusting the desired control pressure in the range of the first limit pressure or in the range between the first and second limit pressure.

Preferably, the invention provides that the first limit pressure is greater and the second limit pressure is smaller than a pressure that prevails in front of the exhaust air throttle or drops above the exhaust air throttle, which is required for a supercritical gas flow in the exhaust air throttle. This required pressure can be 2 bar, for example. Absolute pressure. This ensures that during the control of the opening cross-section of the control valve based on the control pressure in the vicinity of the first limit pressure or in the area between the first and second limit pressures, there is always such a pressure in front of or falling above the exhaust air throttle that it is operated in supercritical flow, in particular until the end of the stroke is reached and the control valve closes, preferably while the control pressure falls below the second limit pressure and reaches the third limit pressure.

The first limit pressure is preferably 1% to 25% higher than the pressure required for supercritical flow, e.g. the required pressure can usually be 2 bar. Due to the required control range below the first limit pressure, a value of 2.3 bar is preferred for the first limit pressure. More preferably, the second limit pressure is at least 5% to 50% lower than the pressure required for supercritical flow and is preferably 1.5 bar. The third limit pressure is preferably only slightly below the second limit pressure. However, real valve designs usually have larger control ranges, so that with the previously mentioned values a third limit pressure of 1.3 bar, for example, is realistic and fluid-mechanically easy to achieve. Preferably, all of the pressure specifications given for the limit values and the pressure required for supercritical flow are to be understood with a possible variation of plus/minus 10% of the stated value.

One way of controlling the control valve or the valve actuator located therein with regard to the opening cross-section can be that the system has an electronic/electrical control with which the control pressure can be measured, e.g. with a pressure sensor in a gas line section between the opposing chamber and the exhaust air throttle, and with which an electric valve drive for adjusting the valve actuator in the control valve can be controlled depending on the measured value of the control pressure. The valve drive can thus be driven in order to move the valve actuator to increase the opening cross-section, in particular to move it in a first direction with falling control pressure when the Control pressure falls below the first limit value and to move the valve actuator to reduce the opening cross-section, in particular in a second direction opposite to the first, when the further falling control pressure falls below the second limit value, in particular at the end of the stroke of the working element.

However, this type of control requires an active component, in this case the electronic control.

A preferred embodiment, however, can provide that the movement of the valve actuator is purely gas-driven, so that additional electronic control can be omitted.

Preferably, a gas line can be provided for this purpose, with which the control valve is fluidically connected to the opposing chamber, wherein the control pressure acting in the gas line acts on the valve actuator of the control valve. In this way, a force positioning the valve actuator is exerted directly by the control pressure.

Preferably, it can be provided that the valve actuator is preloaded with an actuating force, e.g. by means of a spring acting on the valve actuator, by means of which the valve actuator can be displaced with falling control pressure.

Basically, in this purely fluidic control, the opening cross-section of the control valve is increased in a pressure range between the first and second limit pressure with falling control pressure by the movement of the valve actuator, and in a pressure range below the second limit pressure with further falling control pressure, the opening cross-section of the control valve is reduced by the movement of the valve actuator, until it is preferably completely closed when the third limit pressure is reached.

It can be provided that the valve actuator in the pressure range between the first and second limit pressure and in the pressure range below the second limit pressure, in particular both at the initially caused The valve is moved in the same direction during the enlargement of the opening cross-section and the subsequent reduction of the opening cross-section. This is particularly advantageous because the successive effects are both causally linked to falling control pressure.

This can preferably be achieved if the control valve has a characteristic curve describing the dependence of the opening cross-section and adjustment path, which has a reversing slope at an adjustment path position between the two extreme possible adjustment path positions. For example, a slope reversal in the characteristic curve can be present at the point where the second limit pressure is reached.

It can also be provided that between two areas of the characteristic curve with the opposite sign of the slope there is an area in which the slope has the value "zero".

For example, it can be provided that the control valve has two control edges in the valve body that interact with the valve actuator or two control edges that are each arranged on separate valve actuators connected in series, in particular wherein in a direction of movement of the valve actuator defined by falling control pressure, the opening cross-section can be enlarged in a first movement section by interacting with the first control edge and in a subsequent second movement section in the same direction of movement, the opening cross-section can be reduced by interacting with the second control edge, in particular until the opening cross-section is completely closed.

As already mentioned above, a pressure regulating valve, in particular a pressure reducer with a check valve, can be connected in parallel to the exhaust air throttle which is assigned to the counteracting chamber, through which the counteracting chamber can be filled with gas, in particular by shutting off the exhaust air throttle.

In a possible embodiment of the invention, the invention can provide that a changeover valve is provided in the line area between the control valve and the drive, as well as the exhaust air throttle and the drive, with which in a In a first switching stage, the first chamber can be connected to the control valve and at the same time the second chamber can be connected to the exhaust air throttle, and in a second switching stage, the second chamber can be connected to the control valve and at the same time the first chamber can be connected to the exhaust air throttle.

In this design, it can also be provided that the system has only one exhaust air throttle and only one control valve, but these interact with a respective chamber by switching both in the working stroke and in the return stroke.

Preferably, in this possible embodiment, the exhaust air throttle is always connected downstream to the pressure sink and the control valve on the inlet side is always supplied with gas from the pressure source.

It is also preferred that a pressure regulating valve, preferably a pressure reducing valve, is arranged parallel to the control valve, which always ensures a minimum pressure in the driving chamber by bypassing the control valve which is in the closed position at the end of a working stroke. If the reversal of the direction of movement of the drive is initiated by switching the switching valve, there is always sufficient pressure available in the previously driving chamber, so that decompression of the chamber which now counteracts the movement causes pressure to build up in front of the exhaust air throttle, which causes the control valve to open via the control line and the resulting force exerted on the valve actuator in the control valve, thereby enabling a next pressure-controlled working stroke in the opposite direction. In particular, this pressure regulating valve is intended for starting up the drive system from a completely pressureless state.

Another embodiment can also provide that each of the two chambers is assigned an arrangement of an exhaust air throttle and a control valve with a control line connected to the other chamber, wherein each of the two chambers can be filled with gas through the assigned control valve in a process phase in which the respective chamber acts as a driving chamber, and each of the two chambers in a process phase in which the respective Chamber acts as a counteracting chamber, through which the associated exhaust air throttle can be emptied, in particular whereby in both process phases the respective stroke of the working element takes place with the described pressure control via the currently active control valve.

In this embodiment, one of the arrangements can be connected to the pressure source by means of a changeover valve, while at the same time the other arrangement is connected to the pressure sink.

Preferably, by means of check valves in each of the two arrangements, it can be achieved that when a respective arrangement is connected to the pressure source, the gas flow takes place via the control valve in the direction of the chamber to be filled and a gas flow via the exhaust air throttle is prevented, whereas conversely when connected to the pressure sink, a gas flow takes place via the exhaust air throttle to the pressure sink and a gas flow via the control valve is prevented.

In a further development, it can be provided that a pressure control valve, in particular a pressure reducer, is connected in parallel to at least one of the arrangements, preferably to both arrangements, with which the system can be moved from a pressure-relieved state in both chambers to an operating state, in particular by filling one of the two chambers with gas through the pressure control valve and simultaneously pressurizing and opening the control valve assigned to the other chamber.

The invention can also provide for an arrangement for minimum pressure loading for commissioning the system from a pressure-free state in both chambers to be integrated directly into the control valve.

The invention is described in more detail below with reference to the figures.

Figure 1 shows a first embodiment of the invention with a cylinder-piston unit A as a working element, whose piston 3 separates two chambers 1 and 2. It is assumed here that the working element A executes a working stroke when the piston rod of the piston 3 extends.

By means of a changeover valve 7, a pressure source 4 can be connected to a line L1 and at the same time a pressure sink 6 can be connected to a line L2 or vice versa. In this embodiment, the pressure control according to the invention is only carried out in the working stroke, in particular to ensure that the chamber 1 driving in the working stroke is only filled with gas via the control valve 8 to such an extent that a supercritical flow is present at the exhaust air throttle 5.

For this purpose, it is provided here that the control valve 8, via which the chamber 1 is filled, is located in the line L1, which leads to the chamber 1 that drives the working stroke. A check valve R1 is arranged parallel to the control valve, which prevents an inflow into the chamber bypassing the control valve 8, but allows an outflow of gas from the chamber 1 in the return stroke, especially when the control valve 5 is then closed (as shown here).

During the working stroke, gas from the chamber 2, which counteracts the movement of the piston 3 during the working stroke, is displaced to the pressure sink 6 via the exhaust air throttle 5 and the check valve R2 which is arranged in series with it and opens in the direction of the pressure sink 6.

As an essential aspect of the invention, the invention here provides that a gas line 9 as control line 9 connects the control valve 8 with a line section which lies in the line L2 between the counteracting chamber 2 and the exhaust air throttle 5.

The control pressure acting in this line section, in particular the pressure falling across the exhaust air throttle 5, acts via the control line 9 on the valve actuator in the control valve 8 and can influence the position of the valve actuator and thus the opening cross-section of the control valve 8, according to the invention in such a way that with falling control pressure, when the control pressure falls below a first limit pressure, the opening cross-section is enlarged so that more gas flows into the driving chamber and when the pressure falls below a second limit pressure, which is smaller than the first limit pressure, the Opening cross-section is reduced, preferably completely closed, in particular when a third limit pressure is reached, preferably which is smaller than the second limit pressure.

The control pressure is thus kept in the control range around the first limit pressure until the second limit pressure is undershot. This can preferably be selected so that a supercritical flow is achieved in the exhaust air throttle, the first limit pressure is thus greater than the minimum pressure required for the supercritical flow. The second limit pressure is preferably smaller than this minimum pressure.

At the end of the stroke of the piston 3, it can no longer displace gas from the chamber 2, so that the control pressure drops below the second limit pressure and the control valve 8 reduces its opening until it closes, preferably when the third limit pressure is reached or undershot.

A return stroke can be initiated by switching the changeover valve 7. In this case, connecting the pressure source 4 to the line L2 closes the check valve R2 and opens the check valve R3, which is in series with a pressure control valve 12, through which the chamber 2 is filled for the return stroke. The gas then displaced from the chamber 1 can escape unhindered to the pressure sink 6, e.g. to the environment via the open check valve R1. The pressure build-up in the chamber 2 simultaneously ensures that the valve actuator in the control valve 8 is subjected to force via the control line 9, so that it opens again, in particular when the third limit pressure is reached or exceeded, and initiates the next working stroke. The pressure conditions required for cyclical working strokes are thus maintained. The system can be started from a rest position by pressurizing the chamber 2.

Figure 2 shows a design in which a pressure-controlled movement of the piston 3 takes place both in the working stroke and in the return stroke based on the control pressure in the control line 9.

Here too, the control valve 8 is provided in line L1, which in this design is constantly connected to the pressure source 4. The pressure sink 6 is constantly connected to line L2 with the exhaust air throttle 5.

The main difference to Figure 1 is that the changeover valve can now be used to connect chamber 1 to the control valve and chamber 2 to the exhaust air throttle, or vice versa. The previously described pressure control with the control valve 8 therefore always takes place with respect to the currently driving chamber of both chambers 1, 2, and the exhaust air throttling always takes place in the gas that flows out of the currently opposing chamber.

The pressure control valve 12 can be provided to achieve a minimum filling of the previously driving chamber, a pressurization of the control line 9 and an opening of the control valve 8 in an initial pressureless state of both chambers in the switching position shown here with the control valve closed (at the end of the working stroke). The system is thus returned to its regular operating state and can execute a movement by switching the switching valve.

The Figure 3 shows a further possible embodiment in which each of the two chambers 1 and 2 is assigned an arrangement AN1 or AN2 comprising a control valve 8 and an exhaust air throttle 5. The control line 9 of a control valve 8 that is assigned to a specific chamber has a fluid connection to the other chamber.

The check valves R1, R2 in each of the arrangements AN1, AN2 define the required flow direction. R1 allows flow through the control valve 8 to the chamber, while R2 simultaneously blocks flow through the exhaust throttle when the pressure source 4 is connected to the arrangement AN1 or AN2, and R2 allows flow from the chamber through the exhaust throttle 5, while R1 simultaneously blocks flow through the control valve 8 when the pressure sink 6 is connected to the arrangement AN1 or AN2.

The changeover valve 7 can be used to alternately connect the pressure source 4 and the pressure sink 6 to an arrangement AN1, AN2.

With the same effect described above, pressure control is achieved in the working stroke and the return stroke, or in reversing working strokes, which fulfills the desired pressure criterion in the exhaust air throttling, preferably a supercritical flow.

The invention can provide here that a pressure control valve 11 with a check valve is arranged parallel to the arrangement AN2, through which an initial start-up of the system can take place when both chambers are depressurized, as described above. Furthermore, a pressure control valve can also be arranged parallel to the arrangement AN1, which is not shown.

The Figures 4a and 4b show a possible embodiment of a control valve 8 with a valve actuator 8a, which has two actuators 8b and 8c connected by a tapered area. Such a design of the valve actuator 8a can be provided for all possible designs of the valve 8. The valve actuator 8a is pressurized on the left side by the control pressure from the control line 9 and on the right side by a spring 13, which is arranged in a pressure-relieved space. As the control pressure in the line 9 falls, the valve actuator 8a is moved to the left with respect to this illustration. In the effect between the valve actuator 8a (its actuator 8b) and the control edge SK1, the opening cross-section is increased and in the effect between the valve actuator 8a (its actuator 8c) and the control edge SK2, the opening cross-section is reduced. The opening cross-section between connections 4 (to the pressure source) and 1 (to the chamber/to the controlled volume) can be adjusted depending on the control pressure.

The limit pressures mentioned can be defined by means of the spring 13, the force of which can be adjusted. On the right-hand side, the control valve 8 is relieved of gas pressure at connection 23. In all possible designs of a control valve, the second and third limit pressures can be dependent on the first and can be determined by the spring and the design of the control valve in the geometry of the control edges.

The representation of the Figure 4a shows a position with maximum opening cross-section, which can occur with a control pressure between the first and second limit pressure or preferably at the second limit pressure. Preferably, with increasing control pressure, the control valve can close when the first limit pressure is exceeded, or initially reduce the opening cross-section with increasing control pressure and then close, in particular if no residual opening, e.g. by a mechanical stop, or no parallel flow path is provided, and if the first limit pressure is undershot, according to the invention, the opening cross-section can be increased with decreasing control pressure up to the maximum opening position shown. If the control pressure drops further, the opening cross-section is reduced until it closes at the control edge SK2.

The Figure 4b shows a version of the same control valve of the Figure 4a , in a position in which the first limit pressure can be present in the control line 9. In this case, the control valve is closed at the control edge SK1 and, with a falling control pressure starting from this position, would increase the opening cross-section from the closed position. With an increasing control pressure starting from this position, the control valve 8 would remain closed.

Figure 5 shows a design in which, compared to the Figures 4a and 4b two springs 13a, 13b are arranged coaxially one inside the other. The spring 13b acts directly on the valve actuator 8a, the spring 13a indirectly via the bearing element 14, which can be moved up to the stop 15. This defines a first displacement range of the valve actuator 8a in which both springs work together and a second - when the bearing element 14 is in the stop - in which only the spring 13b acts. The limit pressures and the gradients of the opening characteristics of the two control edges depending on the control pressure can thus be decoupled from one another. The space in which the springs 13a and 1b are arranged is pressure-relieved via the connection 23.

Figure 6 shows an embodiment in which the execution in the Figures 4a and 4b has been extended to include an integrated minimum pressure for starting from a pressureless state. This allows the previously Figures 2 and 3 The pressure reducers 11 and 12 shown and provided for this purpose are omitted.

The piston 20 shown on the right serves to return the after-pressure of the control valve 8 for the minimum pressure application. A spring 21 acts on the piston 20, which is subjected to the pressure regulated by the control valve through the bore 22, in particular the pressure in the driving chamber 1. Connections 1 and 22 are therefore preferably directly connected. The spring 21 has a preload so that the piston 20 only moves to the left when the after-pressure of the control valve 8 is sufficient, i.e. when the pressure in the driving chamber 1 has a minimum pressure predetermined by the spring 21. The space in which the springs 13b and 21 are arranged is pressure-relieved via the connection 23.

The position of the piston defines the spring preload of the springs 13b and 13c. These define the position of the valve actuator 8a both as a function of the control pressure in line 9 and as a function of their preload and consequently the position of the piston 20.

When the piston 20 is in the left extreme position, the spring rates and preloads of the springs 13b and 13c correspond to the nominally required value for the known function of the valve, in particular as described above. A displacement of the piston 20 to the right leads to a displacement of the valve actuator 8a to the right due to partial relaxation of the two springs 13b and 13c.

When the system is completely depressurized, there is no pressure in the control line 9 or downstream of the control valve, i.e. in bore 22. The piston 20 is in its right-hand extreme position, loaded by the springs 21 and 13b. Due to the displacement of the valve actuator 8a to the right, the control valve is consequently actuated via the control edge SK2 and the actuator body 8c. opened. If pressure is applied to the supply line of the control valve, the previously described valve position applies increasing pressure to the controlled volume, which acts back on the piston 20 via bore 22. If this pressure reaches the setpoint, the piston 20 moves to the left, displaces the valve actuator 8a to the left by increasing the tension of the springs 13b and 13c, and closes the control valve via control edge SK2 and actuator 8c.

From this point on, the piston 20 remains in its left extreme position during normal operation of the system and the function of the valve corresponds to the variant in the Figures 4a and 4b To improve the operating behavior, a spring system 21 consisting of disc springs can be used to load the piston 20.

The Figure 7 shows a modification of the designs of Figure 5 and Figure 6 . As far as the information there and in the Figures 4 described functions are not replaced by the functions described below, these also apply to the execution of the Figure 7 .

In a variation of the Figure 6 In this version, the piston 20 no longer acts on the valve actuator via a flexible spring 13b, but rather rigidly via the piston rod 20a. The interaction of the piston 20 and spring 21 is reversed in the direction here. Again, the space in which the spring 21 is arranged is relieved of pressure by the connection 23. Here, the piston 20 is therefore pressurized from the direction of the valve interior with the pressure of the connection 1, e.g. via the line 22, which connects the space to the left of the piston 20 with the connection 1, preferably inside the valve.

As with the Figure 5 the limit pressures and the gradients of the opening characteristics of the two control edges can be decoupled from each other depending on the control pressure. However, this is not done here by the nested springs 13b and 21, but rather by the realization of position-dependent different opening cross-sections in the effect between a control edge, here the control edge SK1 and the valve actuator 8a, in particular in the case of an actuating body, here the actuating body 8b of the valve actuator 8a. This way of influencing the characteristics via position-dependent different opening cross-sections can be carried out according to the invention independently of the other concrete constructions shown in the valve 8.

In order to realize these position-dependent opening cross-sections, an actuating body, e.g. here the actuating body 8b, can have axially running control grooves 8d in its surface, which only run in sections in the axial direction, i.e. not completely over the surface. In this example, the control grooves 8d end in front of the right axial end of the actuating body 8b.

Deviating from the Figures 5 and 6 The control pressure is preferably applied via the connection 9 to the axial face of the right actuator 8b, on which the piston rod 20a also acts. The effect is against the spring 13c on the other side of the valve actuator 8a, which is arranged in a pressure-relieved space via the connection 23. The movement of the valve actuator 8a is in the execution of the Figure 7 compared to the Figures 5 and 6 the other way round.

Claims (11)

1. Gas-powered drive system, comprising a drive (A) having

   a first chamber (1) and a second chamber (2), which are mutually separated by a movable working element (3) of the drive (A), in particular by a piston (3),

   an exhaust air throttle (5) and a control valve (8), wherein one chamber (1) of the two chambers (1, 2) for forming a chamber (1) driving the working element (3) is connectable to a gas source (4), and the other chamber (2) of the two chambers (1, 2) for forming a chamber counteracting the movement of the working element (3) is simultaneously connectable via the exhaust air throttle (5) to a gas sink (6), in particular by means of a switchover valve (7), wherein the driving chamber (1) is assigned the control valve (8) through which the driving chamber (1) is able to be filled with gas from the gas source (4), wherein the opening cross section of the control valve (8) is adjustable as a function of a control pressure prevailing in the flow direction ahead of the exhaust air throttle (5) or decreasing over the exhaust air throttle (5), wherein the opening cross section is able to be enlarged by the control valve (8) when a first limit pressure is undershot in the case of a decreasing control pressure, and characterized in that the opening cross section is able to be reduced, the control valve (8) in particular being able to be closed, when a second limit pressure is undershot in the case of a further decreasing control pressure.
2. System according to Claim 1, characterized in that the first limit pressure is higher and the second limit pressure is lower than a pressure which prevails ahead of the exhaust air throttle (5) or decreases over the exhaust air throttle (5), and is required for a supercritical gas flow in the exhaust air throttle (5).
3. System according to one of the preceding claims, characterized in that said system has an electronic/electrical control unit by way of which the control pressure is able to be measured, and by way of which an electric drive for adjusting the valve actuator in the control valve is actuatable as a function of the measured value of the control pressure.
4. System according to one of preceding Claims 1 or 2, characterized in that a gas line (9) is provided as a control line (9) by which the control valve (8) is fluidically connected to the counteracting chamber (2), wherein the control pressure acting in the gas line (9) acts on the valve actuator of the control valve (8), in particular wherein the valve actuator is preloaded with an actuating force by way of which the valve actuator is able to be displaced in the case of a decreasing control pressure.
5. System according to Claim 4, characterized in that the control valve (8) has a characteristic curve which describes the dependency of the opening cross section and the adjustment travel and at an adjustment travel position between the two possible adjustment travel position extremes has a reversing gradient.
6. System according to Claim 4 or 5, characterized in that the control valve (8) has two control edges which interact with the valve actuator, or two control edges which are in each case disposed on separate valve actuators connected in series, in particular wherein, in a direction of movement of the valve actuator defined by a decreasing control pressure, in a first movement portion the opening cross section is able to be enlarged by interacting with the first control edge, and in a subsequent second movement portion in the same direction of movement the opening cross section is able to be reduced by interacting with the second control edge, in particular until the opening cross section is completely closed.
7. System according to one of the preceding claims, characterized in that a pressure control valve (12), in particular a pressure reducer (12), preferably having a check valve connected in series, is connected in parallel to the exhaust air throttle (5) that is assigned to the counteracting chamber (2), by way of which pressure control valve (12)/pressure reducer (12) the counteracting chamber (2) is able to be filled with gas, in particular while shutting off the exhaust air throttle (5) .
8. System according to one of the preceding claims, characterized in that provided in the line region between the control valve (8) and the drive (A), and the exhaust air throttle (5) and the drive (A), is the switchover valve (10) by way of which, in a first switching step, the first chamber (1) is connectable to the control valve (8), and simultaneously the second chamber (2) is connectable to the exhaust air throttle (5), and, in a second switching step, the second chamber (2) is connectable to the control valve (8), and simultaneously the first chamber (1) is connectable to the exhaust air throttle (5).
9. System according to one of the preceding claims, characterized in that each of the two chambers (1, 2) is in each case assigned an assembly of one exhaust air throttle (5) and one control valve (8) having a control line (9) connected to the other chamber (2, 1), wherein each of the two chambers (1, 2) in a process phase in which the respective chamber (1, 2) acts as the driving chamber is able to be filled with gas through the assigned control valve (8), and each of the two chambers (1, 2) in a process phase in which the respective chamber (1, 2) acts as the counteracting chamber is able to be emptied through the assigned exhaust air throttle (5).
10. System according to Claim 9, characterized in that a pressure control valve (11), in particular a pressure reducer (11), by way of which the system is able to be adjusted from a state in which both chambers are depressurized to an operating state, in particular by filling one of the two chambers (1, 2) with gas through the pressure control valve (11) and simultaneously pressurizing and opening the control valve (8) assigned to the other chamber (2, 1), is connected in parallel to at least one of the assemblies, preferably in parallel to both assemblies.
11. Method for operating a gas-powered drive system, comprising a drive (A) having a first chamber (1) and a second chamber (2), which are mutually separated by a movable working element (3) of the drive (A), in particular by a piston (3), wherein one chamber (1) of the two chambers (1, 2) for forming a chamber (1) driving the working element (3) is connected to a gas source (4), and the other chamber (2) of the two chambers (1, 2) for forming a chamber counteracting the movement of the working element (3) is simultaneously connected via an exhaust air throttle (5) to a gas sink (6), in particular by means of a switchover valve (7), wherein the driving chamber (1) is assigned a control valve (8) through which the driving chamber (1) is filled with gas from the gas source (4), wherein the opening cross section of the control valve (8) is adjusted as a function of a control pressure prevailing in the flow direction ahead of the exhaust air throttle (5) or decreasing over the exhaust air throttle (5) in such a way that the opening cross section is enlarged by the control valve (8) when the decreasing control pressure undershoots a first limit pressure, and characterized in that the opening cross section is reduced, the control valve (8) in particular being closed, when the further decreasing control pressure undershoots a second limit pressure.

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