Abstract:
A hydraulic valve device, in particular an LS directional valve, includes a housing ( 1 ), with a pressure supply connection (P), at least one utility connection (A, B), and a load-reporting connection, and includes a controller ( 5 ) moveable in two directions to at least partly actuate fluid those connections. An adjustable stop device ( 25, 31, 47, 59 ) restricts the stroke length of the travel movements of the controller ( 5 ) or parts of the stroke length in either direction. The stop device ( 25, 31, 47, 59 ) has a stop surface ( 25 ) facing in one movement direction and a second stop surface ( 47 ) facing in the other movement direction on the same axial end region ( 19 ) of a slider piston ( 5 ). A counter stop ( 31, 59 ) is provided for each stop surface ( 25, 47 ). Both counter stops are on the respective same housing end region ( 11 ) of the housing ( 1 ) in a positionally adjustable manner.

Description:
FIELD OF THE INVENTION 
     The invention relates to a hydraulic valve device, preferably an LS directional valve, comprising fluid ports provided on a housing arrangement, such as at least one pressure supply port P, at least one utility port A, B, and preferably a load-reporting port, and comprising a controller. The controller can be moved in one movement direction or another movement direction to at least partly actuate the fluid ports of the housing arrangement. An adjustable stop device restricts the stroke length of the travel movements of the controller or parts of the stroke length in the one direction or in the other direction. 
     BACKGROUND OF THE INVENTION 
     Valve devices of this kind are frequently used to drive hydraulic actuators. In doing so, adjustable stroke stops have the task of limiting the maximum volume flow of a valve section, and thus, the maximum speed of a work function, for instance, the travel movement of the piston of a working cylinder or the working speed of another actuator. For a corresponding stroke limitation, the state of the art provides an adjustable end stop, which interacts with the controller or parts, which are in operative connection with the controller, at both axial end regions, in relation to the axis of the movements of the controller. Document WO 98/05870, for instance, shows such a solution, in which each end stop acts on a measuring piston at one or the other end of a control spool. Such solutions are disadvantageous, inasmuch as both sides of the housing assembly of the valve devices have to be accessible for conducting adjustment measures to the end stops. In many installation positions, a free and unhindered access is only possible on one side. For valve devices actuated by a hand lever, this accessibility on only side is usually the case on the side of the hand lever side. For valve devices actuated by a hand lever, the prior art provides, as a further solution of the adjustment problem, the possibility of making the adjustment for both end stops at the hand lever side. In this solution, an end stop acts directly on the control spool of the controller. The second end stop acts on the hand lever device to limit it to a lever end position. Since the adjustment acts only indirectly, namely through the mechanics of the hand lever device, on the control spool, the stop device operates very inaccurately due to the play, friction and deformation of the adjustment mechanism. Because of the unfavorable translation of the actuation forces, deformations of mechanics and a further deterioration of the adjustment accuracy also arise. 
     SUMMARY OF THE INVENTION 
     The invention addresses the problem of providing a valve device of the type mentioned at the beginning, which makes for an easy, safe and accurate adjustment of the stop device. 
     According to the invention, this problem is basically solved by an improved hydraulic valve device having, as one essential feature of the invention, a stop device with a stop surface facing one movement direction and a second stop surface facing the other movement direction, at the same axial end portion of a spool piston of the controller. Each stop surface has a counter-stop arranged on the same relevant end region of the housing assembly, in a positionally adjustable manner. In this way, not only both counter-stops are accessible from one housing side, but they also act directly on the control spool, i.e. without intermediate mechanical members. The counter stops are therefore only subjected to tension or pressure, resulting neither in perceptible deformations nor in strength issues. The stop device is not only easily and conveniently adjustable, but also ensures a high adjustment accuracy. 
     Particularly advantageously, one stop surface may be formed directly on the front face of the axial end of the spool piston in question. 
     In particularly advantageous embodiments, the spool piston on the relevant axial end portion is provided with a recess to form the second stop surface. The second stop surface is formed by a wall surface of the recess. The wall surface is between the base of the recess and the outer periphery of the spool piston. This stop surface is available at the same axial end portion of the spool piston for each direction of the travel movement. 
     The counter-stop for the stop surface located on the front face of the spool piston may be formed in a particularly advantageous manner at a set-screw extending in the associated end region of the housing assembly and in parallel to the travel axis. The set screw is accessible from the outside of the housing for adjustment purposes. 
     With respect to the adjustable counter-stop for the second stop surface, the arrangement may be advantageously made such that this counter-stop is formed by a stepped surface between the shank of a second set-screw and its radially enlarged head portion provided for engagement in the recess. 
     In particularly advantageous embodiments, a second set-screw is arranged in parallel to the travel axis in the associated end region of the housing assembly next to the first set-screw, and is likewise accessible from the outside of the housing. For this positioning of the second set-screw, the recess of the spool piston forming the second stop surface with a wall surface can be formed by a longitudinal groove extending in the spool piston along the travel axis. 
     For that design of the stop device, the head portion of the second set-screw is located in the longitudinal groove of the spool piston during operating conditions. The set screw shaft extends beyond the closed end of the longitudinal groove. In this configuration, the assembly and disassembly can be carried out by rotating the spool piston. To this end, the arrangement can advantageously be made such that a transverse groove is formed in the spool piston, which transverse groove opens in the longitudinal groove in such a manner that the transverse groove forms, upon rotation of the spool piston, an exit for the head portion of the second set-screw from the longitudinal groove. A break in the wall of the transverse groove forms a further exit for the head portion of the second set-screw leading to the front face of the spool piston. The transverse groove can be positioned such that the head portion can be aligned with the longitudinal groove for insertion into or extraction from it, if the spool piston is rotated in an axial position, which axial position is outside of the operating working stroke range. The break in the wall of the transverse groove is located, offset in the circumferential direction of the spool piston, in a position such that the head portion can leave the transverse groove in the axial direction at this mounting rotational position of the spool piston. 
     The break in the wall of the transverse groove can be formed in such that a flat beveling extending along a chord at the circumference of the spool piston is provided at the spool piston. 
     In exemplary embodiments of the valve device in which manual actuation is provided, the arrangement may with particular advantage be such that a recess extends in the spool piston from the bottom of the transverse groove radially inwards, for the engagement of a driver element of a device for manual generation of travel movements. 
     Furthermore, in particularly advantageous exemplary embodiments, at the housing arrangement, a guiding device for the spool piston may be arranged such that it secures the spool piston against rotation only in axial positions corresponding to the operational working stroke range. Outside this working stroke range, the guiding device releases the spool piston for rotation into the mounting rotational position. 
     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: 
         FIG. 1  is a side view in section of a valve device according to an exemplary embodiment of the invention, only partially displaying the housing assembly; 
         FIG. 2  is an end view in section of the valve device taken along line II-II of  FIG. 1 ; 
         FIG. 3  is a side view in partial section of an axial end region of the housing assembly of the exemplary embodiment; and 
         FIG. 4  is a perspective view of a part of the end region of the housing assembly of the exemplary embodiment, having the stop device, drawn to a larger scale. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the drawings, the valve device according to the invention is explained using the example of an LS-directional valve.  FIG. 1  shows only the main housing parts of the housing assembly  1  functionally connected to the hydraulic controller, namely a control housing  3 . A control piston  5  of the controller can be moved in control housing  3  along a travel or longitudinal axis  7 . Housing end regions  9  and  11  close the control housing  3  at both axial ends. The control housing  3  has housing ports typical for such valve devices, such as a pressure supply port P, two utility ports A and B. Other ports, such as tank-return ports or ports for a pressure balance for instance, are not numbered in  FIG. 1 . The control piston  5  of the controller as such is controlled in a known manner and is therefore not described in more detail, by conventional, electromagnetically operated pilot valves  13  and  15 . A spring assembly  17  located in the housing end region  9  specifies a neutral or center position for the control piston  5  in the usual in way for such directional valves. As the valve function in this respect conforms with the prior art, the following description will be directed only at the axial end region  11  shown on the right in  FIG. 1 , containing the stop device for the stroke limitation of the control piston  5  and its axial end portion  19 . 
     This housing-end region  11  is connected to the control housing  3  of the multi-part housing assembly  1  in a sealed manner and has an internal cylindrical pressure chamber  21 , extending along the travel axis  7  and into which pressure chamber  21  the end portion  19  of the spool piston  5  extends. The inner diameter of the pressure chamber  21  is larger than the outer diameter of the end portion  19  of the control piston  5 , and has an axial length, such that the closed end  23  is located outside of the operating working stroke range of the control piston  5 . Control piston  5  therefore does not touch the end  23  of the pressure chamber  21  in the most extreme approach of its axial end surface  25  to the pressure chamber end  23 . A connection  27  from the pilot valve  15  opens into the pressure chamber  21  in the vicinity of the end  23 . 
     The details of the adjustable stop device are clearly visible in  FIGS. 2 to 4 , which show the housing end region  11  in a separate representation. The stop surfaces, limiting, in conjunction with the associated counter-stops of the adjustable stop device, the strokes of the travel movements of the control piston  5  in one or the other direction of movement, are both formed at the end portion  19  of the spool piston  5 . The first stop surface, which limits the stroke of the spool piston  5  towards the end  23  of the chamber  21 , is formed by the front face  25  of the spool piston  5 , which has the shape of a radial plane. As an adjustable counter-stop for the front face  25 , a set-screw  29  is provided in the form of a threaded bolt. One end  31  of shank  30  of set screw  29  forms the counter-stop for the front face  25  as stop surface of the control piston  5 . The other, outer end of the shaft  30  is provided with a hexagon socket  33 . The set-screw  29  passes through a threaded bore  35 , which extends in close proximity to the travel axis  7 , in the housing end region  11  in parallel to the axis  7 . The set-screw  29 , which becomes rotatable by inserting a rotating tool at the hexagon socket  33  for positional adjustment, i.e. for limiting the stroke, can be retained in its respective adjusted position using a collar nut  37  having sealing function. Collar nut  37  abuts the outside of the housing end region  11  with its flange-shaped, extended collar  39 . The collar  39  is seated in a shallow depression  41 . 
     The second stop surface, opposite the front face  25 , which front face  25  acts as the first stop surface, is formed at the end portion  19  of the spool piston  5  in close axial proximity to the front face  25 . The end portion  19  has a special shape, as indicated in particular in  FIGS. 2 to 4 . To this end, a recess has been formed in the end portion  19  in the form of a longitudinal groove  43  incorporated in the circumference of the end portion  19  of the control piston  5 . Groove  43  extends axially parallel over almost the entire axial length of the end portion  19  in the direction of the front face  25 , but which ends at a distance therefrom, resulting in a non-recessed area  45  between the front face  25  and the longitudinal groove  43 . On the inside of non-recessed area  45 , a wall surface  47  forms an axial boundary of the longitudinal groove  43 . This wall surface  47  serves as the second stop surface of the adjustable stop device. 
     A second set screw  49  is provided as a positionally adjustable counter-stop for the wall surface  47  of the longitudinal groove  43  acting as the second stop surface. Shaft  51  of set screw  49  has threaded portion  53  extending through a threaded bore  55  in the housing end region  11 . Threaded bore  55  extends axially parallel to and at a distance from the travel axis  7  such that the shaft  51  extends over the non-recessed area  45  of the end portion  19 . A radially enlarged head  57  of set screw  49  engages in the recessed longitudinal groove  43 , however. For this positional arrangement, the head  57  forms, using the stepped surface  59  located between it and the shaft  51 , the second counter-stop for the interaction with the wall surface  47  at the end of the longitudinal groove  43  acting as the second stop surface. 
     As for the first set-screw  29 , the second set-screw  49  is also provided with a hexagon socket  61  at the end for an easy adjustment rotation. In the same way as for the first set-screw  29 , a collar nut  63  is provided for retaining the set position. A radially extended collar  65  of collar nut  63  sits in a recess  41  of the housing end region  11  in the same manner as the collar  39  of the other nut  37 . 
     Because in the present configuration the second set-screw  49  can extend over the non-recessed area  45  of the end portion  19  using its shaft  51 , but not using the radially enlarged head  57 , for assembly/disassembly purposes an exit for the screw head  57  is provided. Via the exit, the screw head  57  can leave both the area of the longitudinal groove  43  and can come clear from the end portion  19  of the spool piston  5 . For this purpose, a second recess in the form of a transverse groove  67  is provided. Immediately adjacent to the end-side wall surface  47  of the longitudinal groove  43 , transverse groove  67  opens into the longitudinal groove  43 . The bottom of the transverse groove  67  has the same radial depth in the end portion  19  as the bottom of the longitudinal groove  43 . The axial width of the transverse groove  67  is adapted to the axial length of the head  57  so that it can enter the transverse groove  67 , if the spool piston  5  is rotated correspondingly far from the rotational position shown in the figures. To enable the head  57 , at a corresponding rotation, during which it has left the area of the longitudinal groove  43 , to come completely clear from the end portion  19 , the transverse groove  67  has a beveling  69  in the circumferential region offset in relation to the wall surface  47  of the longitudinal groove  43 . Beveling  69  forms a break in the wall of the transverse groove  67 , radially deepening the circumferential region of the end portion  19  in relation to the non-recessed area  45  such that the head  57  comes clear from the end portion  19  upon a corresponding axial displacement of the end portion  19 . 
     Whereas a rotary movement of the control piston  5  is provided for mounting/dismounting purposes, the spool piston  5  should not be rotatably movable in operation. To this end, an axis-parallel guide rib  71 , projecting into the pressure chamber  21 , is provided at the housing end region  11 . Guide rub  71  engages in an associated axial guide groove  73  in the end portion  19 . In doing so, the axial length of the rib  71  is selected such that it only engages in the guide groove  73  in the normal operating working stroke range. The spool piston  5  is out of engagement with the guide rib  71  in axial positions for assembly/disassembly purposes, and therefore, is then rotatable. 
     In the present exemplary embodiment, a device for actuation by hand lever is provided. For this purpose, a further, radially extending recess  75  is incorporated in the end portion  19  in the bottom of the transverse groove  67 . This transverse groove  67  can be engaged with a rounded driving head  77  at the end of a pivot lever  79 . Pivot lever  79  is pivotable around a pivot axis  81  using a hand lever (not shown in the drawing). The pivotability is designed such that the driving head  77  can enter the recess  75  for a fully counterclockwise pivoted position of the pivoting lever  79  and a corresponding axial position of the end portion  19 , but cannot leave the recess  75  in axial positions corresponding to the operational working stroke range. As shown in  FIG. 2 , the pivot lever  79  is located at the end of a pin  83 , which is located in a sealed lead-through  85  screwed into the housing end region  11 , which is externally sealed from the end region  11  by a sealing element  87 . A hand lever for the manual rotary operation mounted on a hexagon head  89  of the pin  83  has been omitted in  FIG. 2 . 
     While the present exemplary embodiment relates to an LS-directional valve, the adjustable stop device according to the invention can be likewise advantageously used for other types of valve devices, in which a stroke limiter of the hydraulic controller is desirable or required. 
     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.