Abstract:
A control device selectively fluidically connects and disconnects fluid connection points (A, P, T) by a valve ( 5 ), which controls fluid-conducting connection channels ( 55, 57, 59 ) extending between the connection points (A, P, T). The connection channels are arranged in a control block ( 3 ), into which the valve ( 5 ) is at least partially inserted. Proceeding from the respective fluid connection points (A, P, T), the connection channels ( 55, 59, 57 ) connected to the fluid connection points extend in parallel to each other until the connection channels lead into a respective control chamber ( 49; 53, 51 ). The valve ( 5 ) is retained in a receptacle ( 39 ) separating two adjacently arranged control chambers ( 49, 51 ) from each other.

Description:
FIELD OF THE INVENTION 
     The invention relates to a control device for selectively fluidically connecting and disconnecting fluid connection points by a valve apparatus. The valve apparatus controls fluid-conducting connection channels extending between the connection points. The connection channels are arranged in a control block, into which the valve apparatus is at least partially inserted. 
     BACKGROUND OF THE INVENTION 
     Control devices of this type are very frequently used for mobile work machines for the electro-hydraulic control of couplings and hydraulic actuating elements. Valve apparatuses in the form of proportional pressure control valves, such as 3/2-way gate valves, are usually used in this context. The couplings and hydraulic actuating elements to be controlled are built into transmission casings in these applications. The valve apparatuses are usually formed by cartridge valves inserted into a corresponding control block, with the control blocks being flange-mounted at the sides on the respective transmission. In light of the fact that, in the case of tractor transmissions, for example, more than ten valves may be required to control couplings and actuators, and that each of the valves is to be connected to a pump connection and a tank connection, and the working connection of each valve is to be connected to the respective coupling or actuating element to be controlled, considerable construction expenditures and cost expenditures are involved in the formation of the required fluid connection paths together with the associated pipework. 
     SUMMARY OF THE INVENTION 
     In light of this problem, an objective of the invention is to provide an improved control device of the aforementioned type, which is distinguished by a design that can be economically produced and by an advantageous operating behavior. 
     This objective is basically achieved according to the invention by a control device having, as a significant distinctive feature of the invention, proceeding from respective fluid connection points, connection channels respectively being connected to the fluid connection points and extending parallel to each other until the connection channels open into a respectively assigned control chamber of the valve apparatus. The valve apparatus is held in a receptacle, which separates at least two adjacently arranged control chambers from each other. Because the receptacle, which forms a seat for the valve apparatus in the installation space, forms a sealing point between control chambers, which are axially offset relative to each other in the case of the gate valves in question, terrace steps which are axially offset relative to each other are formed in the installation space. Terminal connection channels can then be formed in a simple and economical manner by bores extending in parallel. The bores can extend in any direction relative to the valve axis, i.e. also vertically or slightly inclined. Since the connection channels to the respective steps of the valve, which steps are offset relative to each other in axial directions in the case of the valves in question, such as cartridge valves, no longer have to extend vertically relative to the valve axis. 
     A particularly advantageous option is forming connection channels extending parallel in any direction relative to the valve axis, for example parallel to the valve axis or slightly inclined relative to the valve axis. The ability to freely configure permits an economical production and a design with very short fluid connection paths, which short fluid connection paths improve the dynamics of the operating behavior. 
     Advantageously, the valve apparatus can be provided with a casing, which itself at least partially forms a control chamber and/or which has at least one bore that opens into a control chamber. This arrangement results in particularly short fluid connection paths. 
     In particularly advantageous exemplary embodiments, in view of the parallel arrangement of the connection channels, the receptacle for the valve apparatus can be accommodated eccentrically relative to the displacement axis of the valve gate, which is longitudinally-displaceably guided inside the valve casing, in the control block. 
     Particularly advantageously, the receptacle can be formed from a circular cylindrical receiving plate, which has a preferably circular cylindrical recess for receiving the valve casing. The center axis of the recess extending parallel to the center axis of the receiving plate is arranged offset relative to same. This offset allows the connection channel bypassing the receiving plate to bring the recess closer to the valve axis according to the eccentricity, resulting in a saving of installation space required for the control block. 
     As a result, in a particular advantageous manner, the connection channel for the pressure supply connection and the connection channel for the service connection can take up, with their respective longitudinal axis, approximately the same distance to the displacement axis of the valve gate. The longitudinal axis of the connection channel for the tank connection or return connection is then able to be coextensive with the displacement axis of the valve gate. 
     The pressure supply connection channel extending in the control block can be formed such that it is longer than the service connection connecting channel in the axial direction. This service connection channel, in turn, can be formed such that it is longer than the tank connection channel. 
     In addition, in advantageous exemplary embodiments the control chamber into which the pressure supply connection channel opens can lie above the control chamber into which the service connection connecting channel opens, viewed in the actuation direction of the valve gate. These two control chambers can then be separated from each other in a fluid-tight manner by the receptacle. 
     With this arrangement of the receptacle, the control chamber into which the service connection connecting channel opens can lie above the control chamber into which the tank connection channel opens, viewed in the actuation direction of the valve gate. These two adjacent control chambers can be separated from each other in a fluid-tight manner by valve casing parts, which are encompassed by parts of the control block. 
     In particularly advantageous exemplary embodiments, the plate forming the receptacle can be encompassed on the outer peripheral side by a sealing device, which produces the seal between the receptacle and the control block. 
     A particular advantage of the invention is that the control block can be a component of a transmission casing, in particular a mobile work machine, or can be attached to the transmission casing. This arrangement permits, in particular in the case of complete elimination of the control block, a significant cost saving, associated with a corresponding reduction of the required installation space, simplification through less effort invested in pipework and improvement of the operating behavior through better dynamics as a result of shorter connection paths. 
     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 control device according to an exemplary embodiment of the invention; 
         FIG. 2  is a side view of the control device of  FIG. 1 , wherein the installation space area of an assigned control block is depicted in a longitudinal section; and 
         FIG. 3  is a plan view in section take along the line III-III of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the control device depicted in the figures, the valve apparatus has a proportional pressure control valve in the form of a cartridge valve that can be actuated electromagnetically and that is installed with its valve casing  1  in a control block  3 . The control block  3  forms, in a conventional manner, fluid connection points comprising a pressure supply connection P, a service connection with A and a return connection or tank connection with T. A valve piston  5  longitudinally-displaceably guided in the valve casing  1  can be controlled by an actuating device  7  in the form of an actuating magnet so as to assume its individual displacement positions. The actuating device  7  is designed in accordance with the prior art and has, for the purpose of displacement of a magnet armature  9 , a coil winding  13  that can be powered by a plug  11 . The actuating device  7  is designed as a repelling magnet, i.e. when the coil winding  13  is powered, the magnet armature  9  moves downwards as viewed in the direction of  FIG. 1  and exerts, by an actuating plunger  15  formed by an extension of the valve piston  5 , a force on this valve piston, which force triggers a displacement movement of the valve piston  5 . 
     The actuating device  7  has a pole core  17  which, in the installed state, extends with its end  19  into the installation space of the control block  3 . A sealing element  21  forms the seal of the installation space. In the installed state, a flange ring  23  abuts a step  25  of the pole core  17  and forms a flange connection with the control block  3  by fastening screws  27 . The above-described design of the valve apparatus, including a valve spring  29 , which holds the valve piston  5  such that it bears on the magnet armature  9  in a non-positive manner, and a weak-effect counteracting spring  31  on the magnet piston  9 , is known per se. In a likewise known manner, an axial bore  33  in the valve piston  5  forms, together with a transverse bore  35  and via an inclined bore  37  formed in the magnet piston  9 , a channel for a pressure equalization in the case of displacement movements of magnet armature  9  and valve piston  5 , as is likewise known per se in the case of such valve apparatuses. 
     As the figures show, a receiving plate  39  is provided in the installation space in the control block  3  as a receptacle, which forms a seat for the valve casing  1 . The receiving plate  39  has the shape of a circular cylindrical body and has a circular cylindrical recess  41  ( FIG. 1 ), through which the valve casing  1  extends with its circular cylindrical end part  43 . The outer periphery of the end part  43  abuts the recess  41  in a fluid-tight manner. On the outer periphery, the receiving plate  39  is sealed by a sealing element  45  on the control block  3 , where the receiving plate  39  abuts a step  47  formed in the installation space. In this arrangement, the receiving plate  39  forms a fluid-tight partition between a control chamber  49  lying at the receiving plate top in  FIGS. 1 and 2  and a lower control chamber  51  which, in the conventional manner for cartridge valves, are surrounded by fluid passages of the valve casing  1 , which fluid passages are formed by bores  50  and  52 . The valve casing  1  forms a third control chamber  53  with its open end on the end part  43 . 
     Connection channels are formed in the control block  3  for the fluid connection between the connection points for the pressure connection P, the tank or return connection T and the service connection A and the assigned control chambers  49 ,  53  and  51  respectively. Each of these connection channels is formed by bores extending parallel to the displacement axis of the valve piston  5 . A first bore  55  is located at a distance to the displacement axis and connects the pressure supply connection P to the associated control chamber  49 . A second bore  57 , likewise located at a distance to the displacement axis, connects the service connection point A to the control chamber  51 . A third bore  59  is coaxial to the displacement axis and connects the tank connection point T via the open end of the valve casing  1  to the control chamber  53 . The control chamber  53  is sealed relative to the control chamber  51  of the service connection A by a casing part  42  of the control block  3 , which casing part encompasses the end part  43  of the valve casing  1 . As can be seen from the figures, the bore  55  leading to the top control chamber  49  bypasses the receiving plate  39 . The bore  57 , which leads to the control chamber  51  lying on a lower step, is delimited in the upwards direction by the receiving plate  39 . For this purpose, the round body forming the receiving plate  39  has a diameter of such dimensions that it overlaps the bore  57  and, at its circumferential edge, abuts the step  47  of the control block  3 . In order to avoid having to place the opposite bore  55 , which is assigned to the pressure supply connection point P and which the receiving plate  39  must bypass, at too great a distance to the displacement axis, the recess  41  for the passage of the valve casing  1  in the receiving plate  39  is not arranged centrally, but rather eccentrically. Due to this eccentric arrangement, the step  47  on the side of the bore  55  is located at a lesser distance to the displacement axis than the step  47  in the region of the opposite bore  57 . Accordingly, the bore  55  can, although it must bypass the receiving plate  39 , be arranged at approximately the same distance from the displacement axis of the valve piston  5 , as in the case of the bore  57  that helps to achieve a compact design. 
     Because the control chamber  49  adjoining the top side of the receiving plate  39  conducts the pressure of the supply connection point P, while the control chamber  51  adjoining the bottom side conducts the pressure of the service connection point A, the connection plate  39  applies a load to the step  47  in the installation space due to the fact that, during operation, the pressure in the top control chamber  49  is greater/equal to the pressure in the lower control chamber  51 . Thus, in spite of the eccentricity, there is no bending moment acting on the valve body  1 , which could lead to jamming of the valve piston  5 . 
     The ability to form the bores  55 ,  57 ,  59  forming the connection channels axially parallel to the displacement axis of the valve eliminates the need to form transverse bores in a respective casing forming the installation space for the respective cartridge valve. The valves can then be flanged directly on a transmission casing, or the transmission casing itself can form, by parts, installation spaces, which perform the function of respective control blocks. In other words, the invention also permits a direct installation of the control device in transmission casings, because no transverse casing bores are 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.