Abstract:
The valve device consists, according to the invention, of (at least) two part valves which are symmetrical in circuit terms with respect to the existing connections and which are designed, in particular, as four-way, two position valves of any desired type of construction, but preferably are provided as slide valves. There is preferably a double slide valve with two cooperating slide valves. The valve device features internal seals and sealing surfaces which minimize wear and damage to the seals as they move across flow ports. The valve device is particularly adapted for use as a fuel control valve for an internal combustion powered motor vehicle having two separate fuel tanks. The valve device permits control over which tank supplies fuel to the engine, and allows controlled mixing of the fuels from each tank.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application claims priority to U.S. provisional patent application Ser. No. 60/655,200, filed Feb. 22, 2005. 

   FIELD OF THE INVENTION 
   The present invention relates to a multiway valve arrangement for use as a fuel tank changeover valve between two fuel tanks of a motor vehicle, with two connections for each tank having forward flow and return flow lines. The valve device of this invention enables the forward flow tank connections to be connected alternatively or jointly to the engine and the return flow tank connections can be connected alternatively or jointly to the return flow engine connections. 
   BACKGROUND OF THE INVENTION 
   In certain regions of the earth, for example in the U.S.A., long distances between zones with high average temperatures and zones with very low temperatures are covered by heavy duty motor trucks in intercity transport. Since heavy duty motor trucks are usually operated with diesel fuel, there is a problem that “normal diesel” fuel freezes at about −15° C. At lower temperatures, therefore, diesel powered vehicles have to be operated with another special fuel, what is known as “Arctic diesel”, which still remains liquid even at temperatures down to −40° C. However, Arctic diesel is approximately 10% to 15% more costly than normal diesel and, moreover, also gives rise to a fuel consumption which is about 10% to 15% higher. The aim, therefore, is to avoid operating the vehicle with Arctic diesel only, that is to say even in warmer regions. It is nevertheless impracticable and also not viable to change over the entire fuel system with tank or tanks and lines in the event of a change between warm and cold regions, that is to say to empty the tanks and refill them completely. 
   Heavy motor trucks are nowadays usually equipped with (at least) two fuel tanks. There is always the possibility, depending on the application, of filling the tanks with an identical or different types of fuel. With the aid of a valve arrangement of the type described in the introduction, the tanks can then be connected individually or jointly to the engine. 
   A known valve arrangement of the generic type mentioned is produced as a multivalve from metal and consists of a large number of individual parts screwed to one another, specifically of four 2/2-way valves (i.e. two-position two flow path valves) which are connected via two T-distributors. Each individual valve is designed as a ball valve and is operated mechanically via pull/push rods. This gives rise to some significant disadvantages:
         long actuation travels of the lever mechanisms (150 to 160 mm)   high weight (approximately 2.5 kg)   screwed connections are not directionally adjustable or are directionally adjustable only with difficulty (with regard to the direction of run of connected lines)   high costs in terms of material and of assembly   high actuation force   only direct manual actuation possible, for which purpose the driver has to stop the vehicle and leave the driver&#39;s cab.       

   The object on which the present invention is based is to provide a motorway valve arrangement of the type mentioned which is improved in order to avoid the disadvantages described and which is distinguished, in particular, by a reduced outlay in terms of material and of assembly, by low weight and by a low actuation force, along with the resulting possibility of automatic (remote) actuation. 
   SUMMARY OF THE INVENTION 
   The valve device consists, according to the invention, of (at least) two part valves which are symmetrical in circuit terms with respect to the existing connections and which are designed, in particular, as 4/2-way valves (i.e. four ports and four possible flow paths and two valve positions) of any desired type of construction, but preferably are provided as slide valves. There is preferably a double slide valve with two cooperating slide valves. This constitutes a cost-effective solution which fulfills all the functions of the known valve arrangement at minimal outlay, but in this case consists of very few individual components. This also results in a low outlay in terms of production and of assembly. The use of slide valves is also highly advantageous with regard to the throughflow properties, because large flow cross sections can be implemented. Thus, there does not have to be a flow around any seals, so that the flow cross sections within the valve arrangement can be even about 20% larger than in the connected lines, even without larger installation dimensioning of the valve arrangement. The switching travels necessary for actuation can be kept lower than 30 mm. 
   The actuation forces are so low in the valve arrangement of this invention that even switching by automatic means, in particular electromagnetically or pneumatically, is possible. Moreover, as compared with the known version, a weight reduction of at least 50% (in the case of manual actuation) or of at least 20% (in the case of automatic actuation) can be achieved. Finally, all the connections can be designed to be directionally adjustable in a very simple way, in particular owing to the use of plug connections. 
   Each part valve of the valve arrangement of this invention has two tank connections for forward flow and return flow and two engine connections for forward flow and return flow, the forward flow engine connections of the valves being connected to one another to form a common forward flow engine connection, and the return flow engine connections of the valves being connected to one another to form a common return flow engine connection. 
   It may be noted, at this juncture, that the preferred double slide valve may, in principle, also be used independently of the special application, specifically as a 6/3-way or 6/4-way valve. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail by means of preferred exemplary embodiments illustrated in the drawing in which: 
       FIG. 1  shows a perspective view of a valve arrangement according to the invention, (without end-face cover elements), 
       FIG. 2  shows a side view of the valve arrangement in the direction of the arrow II according to  FIG. 1 , 
       FIG. 3  shows an axial section in the plane III-III according to  FIG. 2 , 
       FIG. 4  shows a further axial section in the sectional plane IV-IV according to  FIG. 3 , the sectional plane being perpendicular to the view according to  FIG. 3 , 
       FIG. 5  shows, in the form of a detail, an enlargement of the region V in  FIG. 4 , 
       FIG. 6  shows an enlarged view of a cover element in the direction of the arrow VI according to  FIG. 7 , 
       FIG. 7  shows a section in the plane VII-VII in  FIG. 6 , 
       FIG. 8  shows a partially sectional side view of an individual part, specifically of a slide, of the valve arrangement according to the invention, 
       FIG. 9  shows a cross section in the plane IX-IX according to  FIG. 8 , 
       FIGS. 10-13  show illustrations similar to  FIG. 3  in various switching positions of the valve arrangement according to the invention, 
       FIG. 14  shows a side view of the valve arrangement in an advantageous refinement with a pressure medium actuation device, 
       FIG. 15  shows an axial section in the plane XV-XV in  FIG. 14 , 
       FIG. 16  shows an enlarged illustration of the region XVI of the actuation device in  FIG. 15 , 
       FIG. 17  shows an enlarged axial sectional view of an individual part, specifically of an actuation piston, of the actuation device according to  FIG. 15  or  16 , 
       FIG. 18  shows an end view of the actuation piston in the direction of the arrow XVIII according to  FIG. 17 , 
       FIG. 19  shows a side view in the direction of the arrow XIX in  FIG. 18 , 
       FIG. 20  shows a further axial section in the plane XX-XX in  FIG. 18 , 
       FIG. 21  shows a further view of a cover element in an alternative version to that of  FIG. 6 , 
       FIG. 22  shows a part section through the valve arrangement along the sectional line XII-XII in  FIG. 15  with an additional illustration of connecting plugs, and 
       FIG. 23  shows a simplified circuit diagram of the valve arrangement according to the invention as the changeover valve between two fuel tanks and an engine, for example in a switching position such as that in  FIG. 13 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Identical parts are always given the same reference symbols in the various figures in the drawing. 
   As first becomes apparent from  FIG. 23 , a multiway valve arrangement  1  according to the invention is used, in particular, as a fuel tank changeover valve between two fuel tanks A and B and an engine M, only indicated diagrammatically, in a motor vehicle (motor truck). For this purpose, the valve arrangement  1  has tank connections A 1 , A 2  for the tank A and tank connections B 1 , B 2  for the tank B, the connections A 1  and B 1  functioning as forward flow tank connections in each case for a tank suction line  2 ,  4  leading respectively from the tank A and B to the valve arrangement  1 , and the connections A 2  and B 2  functioning as return flow tank connections in each case for a return line  6  and  8  leading back respectively in the direction of the tank A and B. Furthermore, the valve arrangement  1  has two engine connections M 1  and M 2 , the connection M 1  being provided as a forward flow engine connection for a forward flow line  10  leading to the engine M, and the connection M 2  being provided as a return flow engine connection for a return flow line  12  coming from the engine M. The valve arrangement  1  has, furthermore, a valve device such that the forward flow tank connections A 1 , B 1  can be connected alternatively or jointly to the forward flow engine connection M 1  and the return flow tank connections A 2 , B 2  can be connected alternatively or jointly to the return flow engine connection M 2 . As a result, alternatively, either the tank A or the tank B can be connected to the engine, or both tanks A and B can be connected in parallel to the engine. A fourth switching position is preferably also provided, in which both tanks A and B are separated, that is to say shut off, from the engine M. The switching position is illustrated by way of example in  FIG. 23 , the tank B being connected to the engine M, while the other tank A is shut off. As regards the other switching positions, reference is made, at this early stage, to  FIG. 10 to 13 . 
   According to the invention, then, the valve device  1  consists of two cooperating multiway part valves V 1 , V 2 , in particular slide valves  14  and  16 . Each part valve V 1 , V 2  or slide valve  14 ,  16  is designed as a 4/2-way valve and has two of the tank connections, specifically A 1  and A 2 , on the one hand, and B 1  and B 2 , on the other hand, for forward and return flow. The term “four-way” valve is used herein to refer to a valve having four ports and four possible flow paths. Slide valves  14  and  16  are also designated as 4/2-way valves, meaning they are four way valves with two switching positions. The engine connections M 1 , M 2  are connected to both slide valves  14 ,  16 . This results, overall, in a construction as a 6/3-way or 6/4-way valve in six connections (and flow paths) and at least three and preferably four, switching positions. 
   Each slide valve  14 ,  16  has a valve housing  18  and a slide  24  longitudinally displaceable in a piston-like manner between (at least) two switching positions in an elongate cylinder-like slide space  20  within the valve housing  18  in the direction of a slide axis  22  (cf., in this respect, also a separate illustration in  FIG. 8 ). Although two positions are described, a mid-travel or neutral position may also be used. Each slide space  20  has, at points offset axially, that is to say in the direction of the slide axis  22 , four control ports  26  which are connected in each case to one of the tank connections A 1 , A 2  or B 1 , B 2  or to one of the engine connections M 1  or M 2 . Depending on the position of the slides  24 , the control ports  26  can be connected in pairs or can be shut off relative to one another. 
   In the preferred version, two slide valves  14 ,  16  are arranged directly adjacently to one another and, with respect to their slide axes  22 , parallel to one another. In a further advantageous refinement, the two valve housings  18  are in this case combined to form a monolithically one-piece housing molding  28 . This molding  28  is produced, in particular, as a plastic injection molding or as a diecasting, for example from aluminum or zinc. This also contributes to economical production. In principle, however, the molding  28  may also be produced from solid materials by means of cutting machining. 
   The one-piece housing molding  28  with the two valve housings  18  is designed mirror-symmetrically with respect to a central plane of symmetry  30 . Thus, the tank connections A 1 , A 2  and B 1 , B 2  extend in each case outward away from housings in a direction of run parallel (not shown) or perpendicular to the plane of symmetry. The engine connections M 1 , M 2  are arranged centrally with a direction of run corresponding to the plane of symmetry  30 . The engine connections M 1 , M 2  therefore lie centrally between the two slide valves  14 ,  16 . Each engine connection M 1 , M 2  merges into a duct which intersects the slide spaces  20  of the two slide valves  14 ,  16  in order to form the associated control ports  26 . The engine connections M 1 , M 2  are thereby connected to the two slide valves  14  and  16  in a simple way. 
   Each slide  24  has, at points spaced apart axially, circumferential seals  32  which cooperate with inner sealing faces of the respective valve housing  18 . In this case, see, in particular,  FIG. 8 , each slide  24  consists of a centric axial core  36  and of a plurality of, in the version illustrated four, radial dish-like valve disks  38  and also of an actuation end  40  led outward from the respective valve housing  18  on one side. Each valve disk  38 , on its outer circumference, carries one of the circumferential seals  32 , preferably in an annular groove  42 . The circumferential seals  32  may be formed from elastic O-rings. According to  FIG. 8 , it is advantageous if the valve disks  38  have axial undercuts  44  in the region radially between the core  36  and the outer circumference. In the case of a preferred production of the slides  24  as one-piece plastic moldings, material accumulations and consequently distortion are advantageously avoided due to the undercuts  44 . These undercuts  44  are removed from the mold, during manufacture, by means of what may be referred to as a jump core technique. 
   In a further advantageous refinement of the invention, there is in this case provision for the circumferential seals  32 , as regards their outside diameters D 1 , D 2 , D 3  (see, in this respect,  FIG. 8 ) and the sealing faces  34 , as regards their inside diameters D′ 1 , D′ 2  and D′ 3  (see  FIG. 4 ), to be designed in adaptation to one another in such a way that each circumferential seal  32 , which, during a switching action, moves axially over and beyond the region of one of the control ports  26  (in the example illustrated, these are the seals  32   b  and  32   d ; see  FIGS. 4 and 8 ), is essentially unpressed radially in its range of movement extending axially over and beyond the respective control ports  26  and is pressed radially only in a sealing region lying in each case axially between two control ports  26  to be separated from one another. What is avoided by means of this advantageous measure is that one of the circumferential seals  32  could be damaged during its movement over and beyond a control port  26  issuing laterally into the slide space  20 , since, in a pressed state, the seal could expand into the control port  26  and, during further movement, catch at the port edge and thus be damaged. This is avoided by means of the measure according to the invention. 
   In the preferred version, there is provision for the slide space  20  of each valve housing  18  to have, starting from an end  46  open for the actuation end  40  of the slide  24 , a plurality of essentially cylindrical sealing faces  34   a  to c which merge axially one into the other via conical transitions  48  and the inside diameters D′ 1  to D′ 3  of which are reduced successively via the conical transitions  48  (see  FIG. 4  again). It may be noted that the sealing faces  34  may also in each case be designed to be slightly conical, that is to say with a small cone angle ≦1°. This allows a simplified removability from the mold in the case of production as an injection molding or diecasting. The design of the diameters must in this case, of course, be such in relation to the associated circumferential seals that each circumferential seal  32  ensures reliable sealing off in its sealing position in the region of the associated sealing face  34 . As regards the slide  24  (see  FIG. 8 ), the circumferential seal  32   a  which is first, starting from the actuation end  40 , has a diameter D 1  which is adapted to the inside diameter D′ 1  of the first sealing face  34   a  in such a way that this circumferential seal  32   a  is pressed for sealing off. This first circumferential seal  32   a  consequently serves for constantly sealing off the slide space  20  outwardly in the direction of the open end  46 . The next, second circumferential seal  32   b  has, in comparison, a reduced diameter D 2 , so that this second circumferential seal  32   b  is not or at least not completely pressed radially in the region of the first sealing face  34   a . As a result, it can move harmlessly over and beyond the region of the first control port  26 . Thereafter, this second circumferential seal  32   b  is pressed radially via the conical transition  48 , until it then comes to bear sealingly on the second sealing face  34   b  having the inside diameter D′ 2 . There is a similar behavior also with the third and the fourth circumferential seal  32 . Thus, in each position, the third circumferential seal  32   c  is pressed radially and thereby bears sealingly against the sealing face  34   b . Its diameter D 2  accordingly corresponds approximately to the inside diameter D′ 2 . The fourth and last circumferential seal  32   d  has a further-reduced diameter D 3 , so that it is consequently not or only insignificantly pressed radially in the region of this sealing face  34   b  having the inside diameter D′ 2 . It can thereby move harmlessly over and beyond the region of the further control port  26  and is then pressed radially via the further conical transition  48 , specifically according to the inside diameter D′ 3  of the following sealing face  34   c.    
   It is expedient if the valve housings  18  are closed or closable at their open ends  46  by means of a cover element  50 . The cover element  50  preferably also serves for guiding the actuation end  40  of the respective slide  24 . For this purpose, the cover element  50  has in each case a guide orifice  52  with an orifice contour corresponding to the cross section of the core  36  or of an additional guide portion  54 . The example illustrated has a cross section deviating from the circular shape, in particular for example, a cruciform cross section, see, in particular,  FIG. 6 , so that guidance against rotation about the slide axis  22  is also achieved. By virtue of a special, in particular mutually “rotated” arrangement of the guide orifices  52  (cf.  FIGS. 6 and 21 ), a defined installation position of the slides  24  for the correction of possible production-related dimensional deviations in the housing  18  is achieved. For this purpose, the slide  24  may be adapted in shape to the housing and its dimensional deviation. It is in this case advantageous, moreover, if the individual cover elements  50  of the two valve housings  18  are combined via a connection portion  56  to form a one-piece part, in particular a one-piece plastic molding. 
   In a further preferred refinement, each slide  24  is fixed in each of two switching positions with a frictional form fit, in particular via latching means  58 . As may be gathered particularly from  FIG. 5 , the latching means  58  provided may in each case be a latching arm  60  in the region of the guide orifice  52  of the cover element  50 , the said latching arm engaging in each case with a latching nose into a latching recess  62  of the slide  24  or of the guide portion  54 . 
   As indicated highly diagrammatically only in  FIG. 3 , it is advantageous, furthermore, if a sheath  64  variable in length in a concertina-like manner is arranged, for sealing off against dirt, between the actuation end  40  of each slide  24  and the valve housing  18  or the cover element  50  connected to the latter. 
   In the versions according to  FIGS. 1 to 13 , the slides  24  can be actuated manually, in particular via mechanical connections, not illustrated, such as linkages or cable pulls. 
   Alternatively, or even additionally, an actuation device  66  for the motive, in particular pneumatic or hydraulic or electromagnetic actuation of the slides  24  may be provided. 
   For this purpose, reference is made to the exemplary embodiment according to  FIGS. 14 to 16 , in which the valve housings  18  are connected in each case to a cylinder housing  68  on the side of the actuation ends  40  of the slides  24 , preferably additionally to the cover element  50 . The slide actuation ends  40  are connected in each case to an actuation piston  70  guided in the cylinder housing  68 . Each cylinder housing  68  has a control pressure connection S 1  and S 2 . The respective actuation piston  70  can thereby be acted upon with a pressure medium on the side of a working space  71 , in order to displace the associated slide  24 , in particular, counter to the restoring force of a restoring spring  72 . Preferably, in this case, each actuation piston  70  is connected to the actuation end  40  of the associated slide  24  via latching means  74 . In this respect, reference is also made to the separate illustrations of the actuation piston  70  in  FIGS. 17 to 20 . In order to avoid or reduce an excess pressure within the cylinder housing  68  in the event of pressure actuation on that side of the actuation piston  70  which lies opposite the working space  71 , the/each cylinder housing  68  has in this region (at least) one ventilation port  67  which is preferably covered on the outside by a dirt seal  69  resembling a diaphragm valve and taking the form of a toroidal tape (see, in particular,  FIG. 16 ). 
   It is advantageous, furthermore, if the two cylinder housings  68  of the actuation device  66  are combined to form a one-piece molding. This cylinder molding is preferably screwed to the housing molding  28  in the region of the lateral assembly extensions  75 , specifically with the one-part cover element  50  being interposed. Then, according to  FIG. 21 , the latter has matching assembly extensions  75  with screw holes  76 . For positioning and as an assembly aid, positioning extensions  77 , which engage into matching orifices, are provided preferably in the bearing region between the actuation device  66  and the cover element  50  and between the latter and the housing  18  or the housing molding  28  (see, in particular,  FIG. 16 ). By means of a different arrangement and/or shape, for example different diameters, of the positioning extensions  77 , the parts can be connected to one another only correctly and in the right position, so that faulty assembly is advantageously virtually ruled out. 
   In the alternative according to  FIGS. 2 to 13 , according to  FIG. 6  the cover element  50  can be latched with the valve housings  18  or with the housing molding  28  via latching means  78 . In this case, the actuation device  66  may also be fastened via latching means (not illustrated). 
   It is expedient, furthermore, if all the connections A 1 , A 2 , B 1 , B 2 , M 1 , M 2  and S 1  and S 2  provided are designed as coupling parts for the, in particular, directionally variable plug connection of lines. Reference is made, in this respect, to  FIG. 22 , according to which each connection is designed as a socket-like reception orifice  80  for plugging in a plug part  82 . In this case, moreover, suitable locking means  84  for releasable locking of the plug-in plug part  82  are provided. In the example illustrated, each connection has, in the region of issue of the reception orifice  80 , a radially outward-projecting circumferential edge  86 , over which, in the plugged-in state, outer axially extending latching arms  88  of the respective plug part  82  are engaged in a latching manner. For release, the latching arms  88  can be spread radially outward. The advantage of this type of connection is that the direction of run on the connected line (itself not illustrated) is variable, because the plug part  82  can be rotated relative to the connections. In the example illustrated according to  FIG. 22 , each plug part  82  has a conventional connecting dowel  90  for the line connection. 
   The components of the valve arrangement  1  according to the invention, specifically, in particular, the valve housings  18  or the one-piece housing molding  28 , the slides  24  and preferably also the cover elements  50  and, optionally, the cylinder housings  68  and the actuation pistons  70 , preferably consist of the same material, specifically, in particular, of a fiber-reinforced plastic, such as PA12-GF50. This preferred material has low water absorption and is highly suitable for use with fuels, in particular diesel. Leaks, which could arise due to thermal expansion, are avoided, using identical materials for the components. 
   For assembly fastening to a carrier, not illustrated, in a motor vehicle, the housing molding  28  has at least two, preferably three fastening elements  92  which are integrally formed on the outside and, in particular, are arranged so as to be offset axially and/or radially with respect to the regions of the sealing faces  34 , in such a way that, during assembly, a distortion of the molding and dimensional variations resulting from this in the region of the sealing faces  34  are largely ruled out. This ensures good functioning capacity and a permanent sealing action in the region of the circumferential seals  32  and sealing faces  34 . 
   The function of the valve arrangement  1  according to the invention would already seem to be sufficiently clear from the above explanations of this construction. Reference is additionally made to the illustrations in  FIGS. 10 to 13 .  FIG. 10  illustrates an optional shut-off position, in which all existing connections are separated from one another.  FIG. 11  shows the valve position for connecting the tank A to the engine M, in that A 1  is connected to M 1  and A 2  to M 2 . The tank B shut off from the engine M. The opposite switching position is illustrated in  FIG. 13 , the tank A being shut off and the tank B being connected to the engine M. Finally,  FIG. 12  shows the position in which both tanks A and B are connected to the engine M. This switching position is provided with the situation where both tanks are filled with the same fuel. 
   The shut-off position according to  FIG. 10  may be provided as a test position for leaktightness testing. In this case, in the valve, two test chambers are formed, which can be acted upon with a test pressure by the two engine connections M 1  and M 2 . These test chambers are sealed by the circumferential seals  32  of the slides  24 . In the event of a measured pressure drop of the test pressure, a damaged or even absent circumferential seal can be inferred. 
   As a result of the described configuration of the valve arrangement  1  or of the two slide valves  14 ,  16 , the forward flow and return flow of a tank are only ever switched jointly. Misplaced transpositions are thereby ruled out. 
   It may be noted, once again, that a slide valve  14  or  16  of the type described or a double slide valve of the preferred type may also be used, independently of the special application described as a tank changeover valve, as a general 4/2-way (i.e. four-way valve with two switching positions) or 6/3-way or 6/4-way valve. 
   Moreover, the invention is in any case not restricted to the exemplary embodiment described, but also extends to identically acting versions. Furthermore, the invention has also hitherto not yet been restricted to the feature combination defined in the respectively independent claim, but may also be defined by any other desired combination of specific features of all the individual features disclosed as a whole. This means that, in principle, virtually any individual feature of the respectively independent claim may be omitted or be replaced by at least one individual feature disclosed elsewhere in the application. To that extent, the claims are to be understood merely as a first attempt at the formulation of an invention.