Abstract:
A valve, in particular for hydraulic circuits, includes a valve body ( 4 ) designed as a cartridge that can be fixed in a housing ( 6 ) having fluid connections ( 8 ) by a securing device ( 20, 26, 28 ). The securing device has at least one blocking element ( 20 ) in the form of a separate component between the valve body ( 4 ) and the housing ( 6 ). The blocking element has blocking surfaces that can be moved relative to the longitudinal axis ( 18 ) of the valve body ( 4 ) between an assembly position allowing the valve body ( 4 ) to be inserted into the housing ( 6 ) and a blocking position in which the blocking surfaces secure the valve body in an assembly position, preferably with zero backlash by bearing against retaining surfaces ( 26, 28 ) of the housing ( 6 ) and the valve body ( 4 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a valve, in particular for use in hydraulic circuits, having a valve body designed as a cartridge. The valve body can be integrated into a housing that has fluid ducts and can be fixed therein by a securing device. 
     BACKGROUND OF THE INVENTION 
     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 disclose 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. Appropriate tightening torque is required to ensure adequate securing. This securing 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, 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 actuator 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 particularly problematic when the valves concerned are to be inserted into a housing formed by a control block, in which multiple valves are to be arranged next to one another. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an improved valve having a valve body designed as a cartridge that incorporates the advantageous developments of the prior art, that permits a particularly easy and quick assembly and that reduces of the installation space required. 
     This objective is basically achieved according to the invention by a valve having, as an essential feature of the invention, a securing device including at least one blocking element in the form of a separate component located between the valve body and the housing. The blocking element has blocking surfaces that can be moved relative to the longitudinal axis of the valve body between an assembly position allowing 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 screw or threaded connections, such as a central thread or flange screw connections, a plug-type connection. The assembly then dispenses with screwing processes. Also, no need exists to attain specific torques. Thus, easy and quick valve assembly is allowed. Additional screw retentions are likewise dispensed with. This arrangement 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. The annular body can be expanded for an installation operation into the assembly position by elastic deformation. When the installation position is reached, the annular body assumes the blocking position by recovery of shape. In the blocking position, the annular body 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 that, with an assembly operation realized by 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 annular body is accommodated in an installation space situated in the housing. That installation space, relative to the longitudinal axis defined by the valve body, has a radial depth allowing an expansion of the snap ring and is axially delimited on the side facing the installation opening of the housing by an angular surface. The angular surface forms the retaining surface of the housing and 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 snap ring can be sufficiently expanded to allow the insertion of the valve body. 
     Particularly preferably, an additional angular surface is situated on the valve body in front of a section having the largest external diameter in the installation direction and forms an insertion chamfer. The insertion chamfer 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, particularly preferably, 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. The distance between them as they extend is then reduced to a value that is smaller than the cross-sectional diameter of the snap ring. By selection of the angle of convergence of the housing-side angular surface and the valve body-side angular surface, the snap ring, in the course of its recovery of shape, in other words, as a result of its elastic force, is ensured to clamp onto both retaining surfaces. This arrangement 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. Any 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. Also, a groove is provided in the valve body extending axially, and a bore is provided in the housing, extending axially from the installation space. The groove and the bore form 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 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. A twisting of the connection cable can result in damage thereto and to the corresponding plug connector. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure: 
         FIGS. 1 and 2  are side views respectively showing a cartridge valve according to the prior art, wherein two different designs of the securing device thereof are depicted with the respective housing being cut open; 
         FIG. 3  is a partial side view in section illustrating the functioning of a valve securing device according to an exemplary embodiment of the invention; 
         FIG. 4  is an enlarged partial side view in section of only the one side of the securing device according to the exemplary embodiment of the valve according to the invention; 
         FIG. 5  is a perspective view of a snap ring as a component of the securing device of the exemplary embodiment of the invention; 
         FIG. 6  is a side view of the valve according to the exemplary embodiment of the invention with the housing cut open; and 
         FIGS. 7 and 8  are plan views in section of the exemplary embodiment, in which two different anti-twist protection designs are shown. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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  2 . This actuating magnet serves, in the method corresponding to the prior art, to activate a control piston or a control gate valve that is movable in a valve body  4  and that is not visible. The valve body  4  is mounted by f 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  to generate by 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  is connected to the non-visible pole core of the actuating magnet  2 . Flange  14  projects laterally from the actuating magnet  2  and is screwed at the protruding regions to the housing  6  by fastening screws  16 . 
     The valve according to the invention may conform to the prior art in terms of the actuating magnet  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 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  show the installation opening  22  of the housing  6  and the region  24  having the largest diameter of the valve body  4 . 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  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 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 or second 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 or third angular surface  30  is provided on the valve body  4 , in front of the region  24  having the largest diameter in the installation direction, which angular surface  30  forms an insertion chamfer. The installation chamfer 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             in  FIG. 3 , which angle measures less than 45°, and preferably measures approximately 30°. To provide space for the expansion, the snap ring  20  is accommodated in the housing  6  in an annular groove  32 , the radial depth d 2  of which is greater than the cross-sectional diameter d 1  of the snap ring  20 . The first angular surface  26  provided on the housing  6  extends from the radially outer end of the groove  32  to the installation opening  22  and forms an angle β with the radial plane  34  ( FIG. 3 ). The radial plane  34  is perpendicular to the longitudinal axis. The additional angular surface  28  extends on the valve body  4  from the region  24  having the largest diameter to a peripheral area  36  with a reduced external diameter. Peripheral area  36  forms together with the installation opening  22  a slot. Additional angular surface  28  extends relative 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 in a direction radially inward. 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 snap ring cross-sectional diameter d 1 , at a location before the snap ring  20  comes to bear against the peripheral area  36  of the valve body  4 . In the installation position, a gap  38  ( FIG. 4 ) then 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  then 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 a seal 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 in the valve body  4  in longitudinal direction and with 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  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 d 1 . 1  of which is slightly larger than the cross-sectional diameter d 1  of the snap ring  20 . The groove  50  adapted to the cross-sectional diameter d 1  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. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.