EP0439242B1 - Linear actuator - Google Patents

Description

The invention relates to a linear unit with a cylinder, a pressure medium-actuated piston running in a bore of the cylinder, a slide running on the cylinder, a belt connecting the piston to the slide and guided via deflection means on heads of the cylinder, and with valves screwed into the heads for supplying and removing pressure medium into the bore on both sides of the piston.

A linear unit of the type mentioned above is known from DE-A 37 41 425.

In the known linear unit, the valves are used as valve cartridges in corresponding cavities in the cylinder heads and are therefore integrated in the linear axis.

In a further linear unit known from DE-A 32 35 784 with a piston provided with a piston rod, the valves are screwed from the outside into a corresponding threaded bore of the cylinder heads by means of a threaded connector and thus protrude radially outward from the cylinder heads.

In these known linear units it is disadvantageous that the design of the valve to be screwed in is already predetermined by the cartridge receiving bore in a linear unit according to DE-A 37 41 425, or a threaded bore in a linear unit according to DE-A 32 35 784, because Usually miniature valves of the type of interest here also have different external dimensions or connecting threads, depending on the size. It is therefore not possible with the known linear units for one and the same linear unit, i.e. With unchanged cylinders, pistons and cylinder heads, depending on the requirements of the linear unit, different valves can be used without having to change the cylinder heads at the same time.

Furthermore, the known linear units have the disadvantage in common that the electrical connection and the pressure medium connection (usually a pneumatic connection) are each rigidly specified, that is, the circumferential position of the pressure medium connection and the electrical connection is also specified by the final installation position of the inserted or screwed-in valve. In this way, it is only possible with the known linear units, these connections in a certain Direction from the valves. On the other hand, the necessary cables and hoses have to be routed to central units, for example to a central unit of a handling system, of which the linear unit is a part. If this central unit is now in the opposite direction, the cable or the hose must be bent out of the peripheral position determined by the installation position of the valve in the opposite direction and guided to the central unit. It is obvious that this reduces the degrees of freedom when assembling complex handling systems. This is particularly disruptive because such handling systems are often to be built extremely compact and it is also undesirable because of the desired freedom of movement of such handling systems that cables and hoses hang around and thus restrict the freedom of movement of the handling system.

A solenoid valve is known (DE-A1-33 38 418) with a pressure medium supply connection, a pressure medium connection and a relief connection. The solenoid valve also has a valve body on which one of the two pressure medium connections is provided. In addition, a connection body held on the valve body, which carries the other pressure medium connection and an adjusting element which is contained in the valve body and has an electromagnetic coil and is adjustable between two switching positions, is provided, which in its two switching positions releases the flow path between the pressure medium supply connection and one of the two other connections. This known solenoid valve is aimed at the task of adapting to the various conceivable conditions and connection geometries in a flexible manner in a compact design. For this purpose, the valve body is designed as a circular cylindrical sleeve, the adjusting member is designed as a valve cartridge which is mounted in the interior of the sleeve. On the outer circumference of the sleeve, a pivoting part forming the connection body is rotatably mounted around the longitudinal axis of the sleeve, which consists of a ring that cannot be lost on the sleeve and a radially projecting connection piece as one of the two pressure medium connections. To produce the pressure medium connection between the connecting piece on the swivel part and one of the pressure medium channels of the valve cartridge, an annular pressure medium space is provided between the sleeve and the swivel part. The person skilled in the art understands this construction as follows: The valve cartridge has its own pressure medium channels, through which the two working connections, namely the pressure medium supply connection and the pressure medium connection, are connected to one another when the switch position is appropriate. Pressure valve channels must run through the valve cartridge. In its two switching positions, the valve cartridge sets the flow path between the pressure medium supply connection and one of the other two Connections ready. Thus, the valve cartridge as an adjusting element is a central element of the solenoid valve, which is traversed by pressure medium channels for the production of the flow paths. This nested design still has a larger diameter, although the compactness of the solenoid valve seems to allow an unprecedented degree of miniaturization. For this it is necessary that the swivel part, valve body and valve cartridge are integrated into one another and nested, as can be clearly seen in FIG. 3 of the drawings of DE-A1-33 38 418. It is also immediately obvious that this compact design requires a certain configuration of the valve cartridge. However, such a design is not always desirable. It is also possible to design a miniaturized solenoid valve without the nested design.

The invention is therefore based on the object of developing a linear unit of the type mentioned in such a way that there is greater freedom both when equipping the cylinder heads of the linear unit with valves and when laying the connection connections, so that overall flexible and compact linear units are provided can, as they are required in handling systems.

This object is achieved in that the valves each have a swivel screw connection and a cartridge part rotatably connected to the swivel screw connection and are screwed into the heads by means of the swivel screw connections, that in each case a valve seat is integrated in the swivel screw connections and that at least one pressure medium connection goes off the swivel screw connection .

The provision of a swivel screw connection with an integrated pressure medium connection has the advantage that the pressure medium connection can be rotated through 360 ° around the longitudinal axis of the valve, so that the pressure medium line, which is particularly critical in this regard, can be exactly aligned in its outgoing direction so that it can be led to the central unit in the shortest possible way. The use of the swivel screw connection with an integrated valve seat also has the advantage that the swivel screw connection also serves as an adapter, which can be screwed into the corresponding threaded bore of the cylinder heads with a single defined thread, but on the other hand allows the attachment of a large number of valve types. Depending on the application of the linear unit, it is therefore possible to use different valves without changing the design of the cylinder heads by placing different valves on the integrated seat of the swivel screw connection as required.

In a preferred embodiment of the linear unit according to the invention, the pressure medium connection serves to supply the pressure medium.

This measure has the advantage that, as already mentioned, the pressure medium hose, which is particularly critical with regard to its flexibility, can be precisely aligned.

In a further preferred embodiment of the invention, a further pressure medium connection is used to discharge the pressure medium, and this can preferably be provided with a throttle or a silencer. The provision of a throttle allows the travel speed of the piston to be adjusted, and the provision of a silencer permits low-noise operation.

Finally, an embodiment of the invention is particularly preferred in which a switch box for the electronic supply and for pressure medium supply of the valves is arranged on the cylinder, the switch box being connected to a central unit via an electrical connection cable and a supply hose.

This measure has the advantage that the usually two valves of a linear unit with short hose and line pieces can be connected to the switch box, which is conveniently located in the middle of the cylinder between the two cylinder heads. In this case, the swivel fittings are aligned inwards, so that the hose and cable connections only have to be half as long as the length of the cylinder. To supply the entire linear unit, only a single supply hose is required, or two supply hoses when the exhaust air is ducted, and a single electrical connection cable. In an advantageous manner, control commands for the valves can then be transmitted either directly via the connecting cable or just a start or a stop command for control electronics of the valves integrated in the control box, which processes a predetermined control program after receipt of the start command. The switch box on the cylinder also has the advantage that it has display elements for checking the function of the valves and / or control elements such as proximity switches and the like. Like. Can contain, supply and control. Overall, this results in an extremely compact construction of the linear unit with a minimum of cabling and tubing.

Further examples result from the description of the attached drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own without departing from the scope of the present invention.

Fig. 1

eine Prinzipdarstellung, im Schnitt, durch ein Ventil mit einer Schwenkverschraubung, wie es für eine erfindungsgemäße Lineareinheit verwendet werden kann;

Fig. 2

eine Außenansicht, in perspektivischer Darstellung, eines Ventils ähnlich demjenigen der Fig. 1;

Fig. 3

eine schematisierte Darstellung, im Schnitt, durch ein Ausführungsbeispiel einer erfindungsgemäßen Lineareinheit mit zwei Ventilen, ähnlich denjenigen der Fig. 1 und 2;

Fig. 4

einen schematisierten Pneumatik- und Elektrik-Schaltplan für einen Schaltkasten, wie er bei der Lineareinheit gemäß Fig. 3 Verwendung finden kann.

Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1

a schematic diagram, in section, through a valve with a swivel screw connection, as it can be used for a linear unit according to the invention;

Fig. 2

an external view, in perspective, of a valve similar to that of FIG. 1;

Fig. 3

a schematic representation, in section, through an embodiment of a linear unit according to the invention with two valves, similar to that of Figures 1 and 2.

Fig. 4

a schematic pneumatic and electrical circuit diagram for a switch box, as it can be used in the linear unit according to FIG. 3.

In the figures, 10 overall designates a linear unit of a conventional type, which is provided with a cylinder head 11 at each end.

1 shows a valve 15 that can be screwed into the cylinder head 11. The valve 15 is divided into a cartridge part 16 and a swivel screw connection 17.

The cartridge part 16 has a housing 20 which is attached on its underside by means of an upper rotary connection 21 to an associated rotary connection 22 of the swivel screw connection 17.

At its upper end, the housing 20 ends in an upper valve seat 23, which is part of a flange 24. A lower valve seat 25 is integrated in the swivel screw connection 17.

The swivel screw connection 17 is connected to the cylinder head 11 via a lower rotary connection 26. It goes without saying that the rotary connections 21, 22, 26 can be fixed by means of screw connections, for example union nuts, but this is not shown in FIG. 1 for the sake of clarity. Overall, the rotary connections 21, 22 and 26 open up the possibility of rotating the swivel screw connection 17, as indicated by an arrow 27, about the longitudinal axis of the valve 15, specifically relative to the cartridge part 16 and the cylinder head 11.

The cartridge part 16 comprises a closure member 30 in the form of a movable magnet armature, which can be deflected in the axial direction by means of a magnet coil 31, specifically against the force of a spring.

A first pressure medium connection 32 extends radially laterally from the swivel screw connection 17 and permits the inflow of a pressure medium, for example compressed air, as with indicated by an arrow 33. A second pressure medium connection 34 goes downwards from the swivel screw connection 17 through the lower rotary connection 26 and allows pressure medium to be introduced into or released from the cylinder head 11, as indicated by an arrow 35. A third pressure medium connection 36 is finally formed by the already mentioned flange 24 in order to discharge pressure medium, as indicated by an arrow 37.

In the position of the closure member 30 shown in FIG. 1, the lower valve seat 25 is closed and the upper valve seat 23 is opened. In this way, there is a connection from the second pressure medium connection 34 via an annular space 38 around the lower valve seat 25, past the magnet coil 31 upwards to the third pressure medium connection 36. In this position of the valve 15, the valve head leading into the cylinder head 11 is shown in FIG. 1 line, not shown, is thus vented from the cylinder bore of the linear unit 10.

If, on the other hand, the closure member 30 is deflected upward by actuating the magnet coil 31, the upper valve seat 23 is blocked and the lower valve seat 25 is opened. In this position, pressure medium can enter the valve 15 via the first pressure medium connection 32 and reaches the second pressure medium connection 34 via the annular space 38 in order to pressurize the cylinder bore mentioned from there.

From Fig. 1 it can be clearly seen that with unchanged orientation of the cartridge part 16 to the cylinder head 11 by rotation of the pivot screw 17 in the direction of arrow 27, the peripheral position of the first pressure medium connection 32nd can be varied by rotating the swivel screw connection 17. This means that a hose connected to the first pressure medium connection 32 can be brought to the valve 15 from any circumferential position.

In the valve 15 'shown in FIG. 2, the design corresponds completely to that of FIG. 1. In addition, however, it is provided that a further swivel screw connection 40 is connected to the flange 24 at the upper end of the housing 20 in order to enable the exhaust air to be collected and also to be able to connect a hose for removing the exhaust air from any circumferential position. This is possible because, as indicated by an arrow 41, the swivel screw connection 40 can be swiveled relative to the housing 20.

Fig. 2 also shows on the underside of the valve 15 'a thread 42 which is used to screw the valve 15' into the cylinder head 11. The thread 42 can be a thread once defined, so that cylinder heads 11 of the linear units 10 can all be equipped with the same counter thread. In contrast, the thread present in the area of the upper rotary connection 21, 22 for connecting the cartridge part 16 and the swivel screw connection 17 can be designed differently depending on the size of the cartridge part 16. The swivel screw connections 17 thus have the function of an adapter in order to be able to use different cartridge parts 16 on one and the same cylinder head 11 or one and the same counter thread for the thread 42. This makes it possible to equip one and the same linear unit 10 with different valves 15, depending on which cartridge part 16 is required for the respective application by different ones To be able to use valve types, for example pressure servo valves or directional servo valves or other valve types or also different valve sizes.

Fig. 2 finally shows with 43 a connecting cable that serves to supply the solenoid 31.

3, the linear unit 10 is shown completely.

A cylinder 50 has a cylinder bore 51 in which a piston 52 runs. The piston 52 is connected on both ends to a flexible band, rope or the like, which is guided through both cylinder heads 11a, 11b by means of seals and is guided again to the outside of the cylinder 50 by means of deflection means 54a, 54b, in particular rollers. There, the band 53 is connected to a carriage 55, which consequently runs counter to the piston 52 on the outside of the cylinder 50.

A switch box 60 is also arranged on the outside of the cylinder 50, for example on half the axial length of the cylinder 50, which is shown only schematically in FIG. 3, but not necessarily to scale.

The control box 60 is subdivided into a pneumatic level 61 and an electrical level 62. The pneumatic level 61 is connected by means of short hose pieces 63a, 63b to the first pressure medium connections 32a, 32b of the valves 15a, 15b, which in the cylinder heads 11a, 11b described screwed. For this purpose, the swivel screw connections 17a, 17b of the valves 15a, 15b are aligned in this way by twisting been that they each point inwards to the switch box 60. In this way, the tube pieces 63a, 63b are as short as possible and are bent only minimally, if at all.

The cables 43a, 43b are led from the valves 15a, 15b to the electrical level 62 of the switch box 60.

From the pneumatic level 61 of the switch box 60, only a single supply hose 64 then needs to be routed and from the electrical level 62 only a single supply cable 65 to a central unit 66. Only if, as in the case of FIG. 2, the exhaust air of the valves 15a, 15b is to be collected and discharged, two hoses are required instead of the hoses 63 and 64. In the example shown in FIG. 3, however, the valves 15a, 15b are provided with silencers 56a, 56b, so that a separate removal of the exhaust air is not necessary. The silencers 56a, 56b interact with throttles 57 (not shown in FIG. 3) (see FIG. 4).

The supply cable 65 from the central unit 66 to the electrical level 62 of the switch box 60 can be used in different ways. Thus, the supply cable 65 can carry supply voltages and have as many wires as valves 15a, 15b can be controlled. In this way, direct control of the valves 15a, 15b is possible from the central unit 66. Alternatively, however, a separate electronic control can also be provided in the electrical level 62 of the switch box 60, which contains a specific work program for the valves 15a, 15b and then only by means of one Start command must be started and, if necessary, stopped using a stop command. In this case, it would only be necessary to route the start and stop commands via the supply cable 65.

The electrical level 62 of the switch box 60 can also be provided with display means, for example light-emitting diodes 67, in order to display working states of the linear unit 10, for example the switching state of the valves 15a, 15b.

This is also clear from FIG. 4, where the electrical and pneumatic connection of the switch box 60 is shown for an exemplary embodiment.

In FIG. 4, in addition, proximity switches 70 can be seen, which can be provided on the linear unit 10 in order to recognize end positions of the slide 55, in order to avoid collisions of the linear unit 10 with other units of a handling system, etc. The proximity switches 70 are in this case Power supply of the valves 15a, 15b connected and transmit their measurement signals via the supply cable 65 to the central unit 66.

On the pressure medium side, the pneumatic level 61 of the switch box 60 in FIG. 4 first shows the throttles 57a, 57b already mentioned at the third pressure medium outlet 36a and 36b of the valves 15a, 15b, which allow the travel speed of the piston 52 to be set.

The silencers 56a, 56b can also be seen downstream of the throttles 57a, 57b, alternatively indicated by dash-dotted lines at 71, the possibility of collecting the exhaust air and removing it altogether via the switch box 60.

Claims (9)

1. Linear unit with a cylinder (50), a piston (52), which travels in a bore (51) in the cylinder (50) and is actuated by pressure medium, a slide (55), which travels along the cylinder (50), a belt (53), which connects the piston (52) to the slide (55) and is guided over deflector means (54a, 54b) at heads (11a, 11b) of the cylinder (50), and with valves (15a, 15b), which are screwed into the heads (11a, 11b), for feeding and removing pressure medium into the bore (51) on both sides of the piston (52), characterised in that the valves (15a, 15b) each comprise a swivelling screw fitting (17a, 17b) and a cartridge part (16a, 16b), which is rotatably connected to the swivelling screw fitting, and are screwed into the heads (11a, 11b) by means of the swivelling screw fittings (17a, 17b), that a valve seat (25) is in each case incorporated in the swivelling screw fittings (17a, 17b), and that at least one pressure medium connection (32a, 32b) extends from the swivelling screw fitting (17a, 17b).
2. Linear unit according to claim 1, characterised in that the pressure medium connection (32a, 32b) serves to supply pressure medium.
3. Linear unit according to claim 1 or 2, characterised in that another pressure medium connection (36) serves to remove pressure medium.
4. Linear unit according to claim 3, characterised in that the other pressure medium connection (36) is incorporated in another swivelling screw fitting (40).
5. Linear unit according to claim 3 or 4, characterised in that the other pressure medium connection (36), which serves to remove pressure medium, is provided with a throttle (57a, 57b).
6. Linear unit according to one or more of claims 3 - 5, characterised in that the other pressure medium connection (36) serves to collect the pressure medium which is removed.
7. Linear unit according to one or more of claims 3 - 5, characterised in that the other pressure medium connection (36), which serves to remove pressure medium, is provided with a sound absorber (56a, 56b).
8. Linear unit according to one or more of claims 1 - 7, characterised in that a switch box (60) for the electrical supply and for supplying the valves (15a, 15b) with pressure medium is arranged on the cylinder (50), the switch box (60) being connected to a central unit (66) via an electrical supply cable (65) and a flexible supply tube (64).
9. Linear unit according to claim 8, characterised in that the switch box (60) contains a program control.

Images