VALVE

The invention relates to a valve, in particular for use in hydraulic circuits, having a valve body which is designed as a cartridge, which can be integrated into a housing that has fluid ducts and fixed therein by means of a securing device.

Such valves, which are known as cartridge valves in technical terminology and which are provided as hydraulic components in hydraulic systems, are known from the prior art. For example, the patent documents EP 1 882 122 B1 and DE 10 2011 010 474 A1 present valves of this type in the form of proportional pressure control valves. As the securing device, a central thread is provided with an external thread being situated on the valve body and an internal thread at an installation opening of the housing, wherein appropriate tightening torque is required in order to ensure adequate securing. This relies for the most part on the stress to be anticipated during operation, the materials used for the valve bodies and the screw mounting housing, and the securing geometry. Even when a required torque is achieved, in order to guarantee that the arrangement is highly secure, additional complex screw retention methods are required, such as adhesive and/or the use of toothed lock washers and the like.

Another known method for securing cartridge-type valve bodies proposes the use of attachment flanges, which can be screwed to the housing and which project laterally from the magnet actuating means assigned to the valve body. A drawback of this known solution is that the laterally protruding flange leads to a significant increase in the installation space required, which is in particular problematic when the valves concerned are to be inserted into a housing which is formed by a so-called control block, in which multiple valves are to be arranged next to one another.

Based on this prior art, the objective of the invention is to provide a valve having a valve body which is designed as a cartridge, the design of which, while incorporating the advantageous developments of the prior art, permits a particularly easy and quick assembly and also reduction of the installation space required.

This objective is achieved according to the invention by means of a valve having the features described in claim 1 in its entirety.

According to the characterizing portion of claim 1, an essential feature of the invention is that the securing device has at least one blocking element in the form of a separate component located between the valve body and the housing, which blocking element has blocking surfaces that can be moved relative to the longitudinal axis of the valve body between an assembly position, which allows the valve body to be inserted into the housing, and a blocking position, in which the blocking surfaces secure the valve body in an installation position by bearing against retaining surfaces of the housing and the valve body. The invention thus envisages, instead of securing by means of screw connections, such as a central thread or flange screw connections, a plug-type connection, so that the assembly dispenses with screwing processes and there is no need to attain specific torques, thus allowing easy and quick valve assembly. Additional screw retention means are likewise dispensed with. This also results in a reduction in the required installation space, because no protruding components, such as a hexagon head for a wrench or an attachment flange, are required. The valve according to the invention is thus particularly suitable for an application in control blocks having a multitude of valves arranged next to one another. The space saving is particularly advantageous in the mobile hydraulics field, for example in construction machinery and municipal machinery, where smaller-dimensioned control blocks also result in a weight reduction.

Particularly advantageously, the respective blocking element can be formed by an annular body surrounding the valve body over at least a large part of a peripheral area, which annular body can be expanded for an installation operation into the assembly position by means of elastic deformation and which, when the installation position is reached, assumes the blocking position by means of recovery of shape, in which position it comes to bear via the blocking surfaces against the retaining surfaces. In this way a plug-type connection of the snap-lock kind is produced which, with an assembly operation which is realized by means of insertion, is automatic as a result of the snap back of the deformed annular element.

In particularly advantageous exemplary embodiments, an annular body is provided in the form of a metal snap ring having a round cross-section.

Particularly preferably, the arrangement may be such that the annular body is accommodated in an installation space situated in the housing, which installation space, relative to the longitudinal axis defined by the valve body, has a radial depth allowing an expansion of the snap ring and which is axially delimited on the side facing the installation opening of the housing by an angular surface, which forms the retaining surface of the housing, which secures the snap ring against movement toward the installation opening. The radial depth of the installation space is greater than the cross-section diameter of the snap ring, so that the latter can be sufficiently expanded so as to allow the insertion of the valve body.

Particularly preferably, the arrangement may be such that an additional angular surface, which is situated on the valve body in front of a section having the largest external diameter in the installation direction, forms an insertion chamfer, which expands the snap ring during the installation operation into the installation space. The deformation of the snap ring thus occurs automatically, without the need for assembly tools, in the course of the insertion movement of the valve body. In particular, the insertion chamfer starts with a smaller diameter than the internal diameter of the blocking element, so that an expansion during the assembly can be more easily realized.

In particularly advantageous exemplary embodiments, an angular surface is provided in the installation direction, following the section having the largest external diameter, in addition to the retaining surface of the valve body interacting with the snap ring.

With regard to the design of the retaining surfaces, the arrangement is particularly preferably such that the first angular surface forming the retaining surface of the housing and the additional angular surface forming the retaining surface of the valve body converge toward the longitudinal axis such that the distance between them as they extend is reduced to a value that is smaller than the cross-section diameter of the snap ring. By means of selection of the angle of convergence of the housing-side angular surface and the valve body-side angular surface, it is possible to ensure that the snap ring, in the course of its recovery of shape, in other words, as a result of its elastic force, clamps onto both retaining surfaces. This provides the particular advantage that during operation the valve is fixed without play in the axial direction because the snap ring is clamped between the retaining surfaces, even if nominal dimensions of the components vary due to manufacturing tolerances, because different dimensions and distances are compensated for by the elastic clamping of the snap ring between the retaining surfaces.

In particularly advantageous exemplary embodiments, the snap ring includes an end part angled away from the ring plane, and a groove is provided in the valve body extending axially and a bore is provided in the housing, extending axially from the installation space, with the groove and the bore forming an engagement space for the end part of the snap ring. The valve body, which is clamped in the installation position by the snap ring is prevented from twisting by means of the snap ring connected non-rotationally to the housing. Anti-twist protection is particularly important when magnetic valves are used, so as to prevent the occurrence of rotational movement during operation, for example as a result of vibrations or the like, and thus a twisting of the connection cable, resulting in damage thereto and to the corresponding plug connector.

The cartridge valves of the prior art, which are depicted in FIGS. 1 and 2, can be designed as proportional pressure control valves and are provided with an actuating magnet means 2. This latter serves, in the method corresponding to the prior art, to activate a control piston or a control gate valve which is movable in a valve body 4 and which is not visible. The valve body 4 is mounted by means of a securing device in a housing 6 that has fluid connections 8. In the design shown in FIG. 1, the securing device is formed by a central thread 10. To realize the screw connection to the central thread 10, the valve body 4 includes a hexagon head 12, in order to generate, by means of a wrench, the tightening torque required for the screw connection. In the example of the prior art shown in FIG. 2, the securing device is formed by a flange screw connection. For this purpose an attachment flange 14 connected to the non-visible pole core of the actuating magnet means 2 is provided, which projects laterally from the actuating magnet means 2 and which is screwed at the protruding regions to the housing 6 by means of fastening screws 16.

While the valve according to the invention may conform to the prior art in terms of the actuating magnet means 2 and the functional design of the valve body 4 and of the housing 6, the fundamental difference compared with the prior art is that the securing device has no screw connections, whether a central thread or a flange screw connection, and is in the form of a plug-type connection. In the exemplary embodiment depicted, this connection is realized as a snap-lock connection by means of a blocking element in the form of a snap ring 20, see FIG. 5, in which the snap ring 20 is depicted separately, and also FIG. 6, which depicts the valve in the snap ring 20-secured installation position.

In the present example, the snap ring 20 is a steel ring having a round cross-section.

FIG. 3 shows the functional principle of the snap-lock connection, which is produced as a result of the geometry of the regions of the housing 6 and the valve body 4 adjoining the snap ring 20. In FIGS. 3 and 4, the installation opening of the housing 6 is identified by numeral 22 and the region having the largest diameter of the valve body 4 is identified by numeral 24. In the region 24, the external diameter of the valve body 4 is only slightly smaller than the internal diameter of the installation opening 22, in order to allow the insertion of the valve body 4 during the assembly operation. In FIGS. 3, 4 and 6, each of which shows the installation position, the snap ring 20 is in a state in which it is expanded to some extent compared with its unstressed nominal diameter, in other words, it is radially tensioned and rests, by means of blocking surfaces formed by its surface, on retaining surfaces for the axial securing of the valve body 4, namely on a first angular surface 26 of the housing 6 and an additional angular surface 28 of the valve body 4. For the insertion of the valve body 4, the snap ring 20 must be expanded further from the depicted position. For this purpose, an additional angular surface 30 is provided on the valve body 4, in front of the region having the largest diameter 24 in the installation direction, which angular surface forms an insertion chamfer, which expands the snap ring 20 during the insertion operation. For a reliable expansion, the third angular surface 30, together with the direction of the installation movement, form an angle identified by y in FIG. 3, which measures less than 45°, and preferably measures approximately 30°. In order to provide space for the expansion, the snap ring 20 is accommodated in the housing 6 in an annular groove 32, the radial depth d2 of which is greater than the cross-section diameter d1 of the snap ring 20. The first angular surface 26, provided on the housing 6, which extends from the radially outer end of the groove 32 to the installation opening 22, forms an angle β with the radial plane 34 (FIG. 3) which is perpendicular to the longitudinal axis. The additional angular surface 28, which extends on the valve body 4 from the region having the largest diameter 24 to a peripheral area 36 with reduced external diameter, which forms together with the installation opening 22 a slot, extends to the radial plane 34 at an angle α. As can be seen most clearly from FIG. 3, the angle α is larger than the angle β, so that the angular surfaces 26 and 28 converge radially inwards relative to one another, i.e., the gap between the angular surfaces 26 and 28 is reduced inwards radially. In the present exemplary embodiment, the angle β is 6° smaller than the angle α. In the present example, the angle α is envisaged as 41°, and the angle β as 35°.

In the present example, the geometry is such that, with the convergence angle of 6°, the distance between the angular surfaces 26 and 28 is reduced at one point to a value that is smaller than the cross-section diameter d1, before the snap ring 20 comes to bear against the peripheral area 36 of the valve body 4. This means that in the installation position a gap 38 (FIG. 4) remains between the snap ring 20 subject to radial tension and the peripheral area 36 of the valve body 4. Because the clamping of the snap ring 20 thus occurs between the angular surfaces 26, 28, before the snap ring 20 reaches a radial end position on the peripheral area 36, tolerance-related dimensional differences are compensated for, so that the formed plug-type connection is always free of axial play. As FIG. 6 shows, the valve body 4 is sealed relative to the housing 6 in the installation position by means of a sealing means in the form of an O-ring 42.

As FIG. 5 shows, the snap ring 20 includes an end part 40 bent away from the ring plane at a right angle. As FIGS. 7 and 8 show, the end part 40 can, in interacting with a groove 46 extending on the valve body 4 in longitudinal direction and an engagement space formed in the housing 6, constitute anti-twist protection for the valve body 4. In the example shown in FIG. 7, the engagement space is formed by a bore 48 formed in the housing 6. During the assembly operation, care is taken to ensure that the groove 46 in the valve body 4 and the housing bore 48 are aligned, so that the angled away end part 40 of the snap ring 20 engages in the groove 46 and prevents the valve body 4 from twisting. In the example of FIG. 7, a smaller angle of twist, of up to approximately 10°, is possible due to the diameter of the bore 48. By contrast, the example of FIG. 8 shows, instead of the housing bore 48, a groove 50 extending in the housing 6 in longitudinal direction, the width d1.1 of which is slightly larger than the cross-section diameter d1 of the snap ring 20. The groove 50 adapted to the cross-section diameter d1 also prevents small rotational movements, however the introduction of the groove 50 is somewhat more complex in manufacturing terms by comparison with the introduction of a bore 48.

The depicted design of the blocking element in the form of a stainless steel snap ring 20 corresponds to a preferred embodiment. However, a snap ring made from another metallic material with sufficient modulus of elasticity can also be used. A plastic ring can likewise be envisaged, if the valve is able to have play in axial direction and the operational forces do not exceed permissible values, and highly-rigid fiber-reinforced plastics are to be given preference for applications. A steel wire, which is threaded into the groove and which is not in a ready-made form, can also be used. In addition, cables can also be used as the blocking element. Both of the last-mentioned variants require a correspondingly dimensioned introduction into the groove, in other words, a radial access to the groove, for example in the form of an inclined borehole.