Patent Publication Number: US-11022105-B2

Title: Connector plate, hydraulic machine having a connector plate, and hydrostatic unit having a hydraulic machine and a hydraulic attachment part

Description:
This application claims priority under 35 U.S.C. § 119 to patent application no. DE 10 2017 203 281.2, filed on Mar. 1, 2017 in Germany; the disclosure of which are incorporated herein by reference in its entirety. 
     The disclosure relates to a connector plate, to a hydraulic machine, and to a hydrostatic unit. 
     In the case of what is known as a compact axle which can also be called a hydrostatic unit in the following text, a drive machine which is usually electric, a hydraulic machine, a hydraulic attachment part, for example a control valve or control valve block, and a hydraulic consumer, for example a hydraulic cylinder, are combined to form a compact structural unit. Here, in particular, space-saving arrangements and therefore configurations of the individual component and of the overall structural unit are desired and advantageous. One possibility is to arrange at least some of the abovementioned components “in line” or in an aligned manner, with the result that a comparatively long, but advantageously narrow installation space can be utilized. 
     Document DE 10 2010 013 008 has disclosed, for example, an axial piston machine of swash plate design for a hydrostatic unit, which has a connector plate with connector bores toward the control block as a connector adapter. Here, said connector bores have internal threads which are provided for screwing connector hoses or connector pipelines. Therefore, comparatively flexible hoses or lines which are intensive in terms of installation space are to be provided between the module of the axial piston machine having the connector plate and the control block which is to be connected to it. 
     It is a disadvantage of said solution that the resulting hydrostatic unit requires a long installation space if assessed in the direction of the driveshaft of the hydraulic machine. In addition, the use of the hoses or pipes for connecting the control block is susceptible to leaks. 
     SUMMARY 
     In contrast, the disclosure is based on the object of providing a connector plate for a hydraulic machine, via which connector plate a hydrostatic unit with a relatively low installation space requirement is made possible. It is a second object of the disclosure to provide a hydraulic machine which makes a hydrostatic unit which saves installation space possible. A third object consists in providing a hydrostatic unit which saves as much installation space as possible. 
     The first object is achieved by way of a connector plate according to this disclosure, the second object is achieved by way of a hydraulic machine according to this disclosure, and the third object is achieved by way of a hydrostatic unit according to this disclosure. 
     Advantageous developments of the inventions are described in the description, drawings, and claims. 
     A connector plate for the mechanical and hydraulic connection of a hydraulic machine, in particular of a hydrostatic axial piston machine, in particular of swash plate design, having a hydraulic attachment part, in particular a hydraulic control valve, is penetrated by hydrostatic connector recesses. The latter have orifices on sides of the connector plate which point away from one another. Here, orifices for the pressure medium connection with the attachment part are provided on one side, and the orifices for the pressure medium connection with the hydraulic machine are provided on the other side. In order to ensure a linear or aligned arrangement of the attachment part with the hydraulic machine in a manner which is simple in terms of apparatus technology, the orifices are oriented in a substantially axially parallel manner with respect to a drive axle of the connectable hydraulic machine. According to the disclosure, first fastening means are provided on the connector plate, via which first fastening means the connection with the attachment part can be carried out in a block-like manner. Block-like means, in particular, that the hydraulic connection can be configured without hoses or pipes, in particular by way of direct and fixed connection of the connector plate to the attachment part. 
     Fundamentally, the type of the connection of the components, both a mechanical and a hydraulic type, are given great importance for the skillful utilization of the installation space. An amount of installation space which can be taken up of a module which consists of the connector plate and an attachment part is reduced in the direction of the driveshaft by way of the block-like, in particular direct and fixed connection which is made possible in accordance with the disclosure. This is true, in particular, with respect to those cases in which the connection of the connector plate to the attachment part has had to take place by means of hoses or pipes. With respect to said case, the block-like connection makes it possible, in addition, that it has less fragile sealing points. The mechanical and fluidic connection can therefore be configured with high strength, reliability and tightness. 
     As a result of the block-like construction of the connection, additional parts which have been necessary up to now for the mechanical/hydraulic connection are omitted or become superfluous. As a result, the overall complexity, in particular a number of parts and a weight, are reduced. The costs for producing the connector plate, the hydraulic machine and the unit are also reduced as a result. 
     Those sides of the connector plate which have the orifices are preferably parallel to one another. In particular, the direction of the driveshaft represents a perpendicular of the sides. The sides are preferably of predominantly planar configuration. An exception to this can be, for example, regions of the sides, in which regions recesses or bulges are provided for functional elements, for example seal or bearing elements. 
     In one preferred development, the connector plate has second fastening means for the block-like (in particular, hose-free or pipe-free) connection to the hydraulic machine. 
     The fastening means are preferably arranged away from the orifices. In relation to the direction of the driveshaft, for example, this can be radially outside the region, in which the orifices are arranged. As an alternative or in addition, individual fastening means or all the fastening means can be provided within said region. 
     In one development, the fastening means have, for example, bores, in particular through bores. 
     Here, the bores can be configured at least in sections with an internal thread or without a thread. 
     In one development, the fastening means have screws in a manner which is appropriate with respect to the bores. 
     It is of course possible in principle that, for example, the first fastening means are provided both for the connection of the connector plate to the attachment part and for the connection of the connector plate to the hydraulic machine. 
     In one preferred development, in each case one of two of the connector recesses of the connector plate can be assigned, in particular is assigned, to a working connector of the hydraulic machine. In particular, a connector which passes into the pressure medium connection with one or more hydrostatic working spaces of the hydraulic machine during operation of the hydraulic machine is considered to be a working connector here. 
     In one development, a third one of the connector recesses can be assigned, in particular is assigned, to a leakage connector of the hydraulic machine. 
     In one development, a fourth one of the connector recesses can be assigned, in particular is assigned, to a load signaling connector of the hydraulic machine. 
     Further connector recesses with associated connectors on the hydraulic machine are possible and increase the degree of integration of the mechanical and fluidic connection via the connector plate. 
     In one development, the attachment part-side orifices represent a hole pattern which is the same as a hole pattern of the attachment part. 
     In one development, the hydraulic machine-side orifices represent a hole pattern which is approximately the same as a hole pattern of the hydraulic machine. 
     The hole patterns which are assigned to one another in this way being the same means that the hole patterns are adapted to one another, at least as far as a number of orifices, their position and/or shape and their function are concerned. 
     In one development, an additional function for the hydraulic machine is configured by the connector plate, by the latter having a bearing seat for the driveshaft of the hydraulic machine. The bearing seat is preferably arranged centrally, in particular concentrically, in relation to the hydraulic machine-side orifices. 
     A hydraulic machine, in particular a hydrostatic axial piston machine, which is configured, in particular, in a swash plate design has a housing and, in addition, a connector plate which is configured in accordance with at least one aspect of the preceding description. Here, the connector plate is connected according to the disclosure via second fastening means to the housing in a block-like manner; in other words, without the necessity of hoses or pipes, in particular in a hose-free or pipe-free manner. 
     It is possible by means of the connector plate which is attached in this way to connect the hydraulic machine to the attachment part in a block-like manner, in particular in a direct and fixed manner, as a result of which installation space which can be taken up in the direction of the driveshaft is reduced, as has been mentioned. Otherwise, the same advantages apply as have already been mentioned in the case of the connector plate alone. 
     The applicant reserves the right to direct a patent request to a module comprising a hydraulic attachment part, in particular a control valve, and the connector plate in accordance with the preceding description. Here, the connector plate is placed onto the attachment part, in particular a valve block or a valve housing of the control valve, and is connected to said attachment part via the first fastening means in a block-like manner, in other words without the necessity of lines or pipes. The attachment part preferably has an associated pressure medium duct for each of the hydrostatic connector recesses or at least for some of them. 
     In one development, the hydraulic machine is configured as an axial piston machine, in particular of swash plate design. 
     In one development, the axial piston machine has a driveshaft and a cylinder barrel which is connected fixedly to said drive shaft so as to rotate with it, in which cylinder barrel cylinder bores are made in a manner which is distributed about the driveshaft. Working pistons are guided displaceably in said cylinder bores, with the result that hydrostatic working spaces are delimited via said working pistons in the cylinder bores. The orifices of said working spaces pass into alternating pressure medium connection with the two connector recesses of the connector plate which are mentioned in the description, upon rotation of the driveshaft. 
     In order for it to be possible to fasten a drive unit to the hydraulic machine, said hydraulic machine has, in one development, an attachment flange for a drive unit, in particular an electric machine, on a side of its housing which is arranged opposite the connector plate. 
     In one development, the hydraulic machine has a control plate which is arranged between the cylinder barrel and the connector plate. The control plate has through recesses, the hole pattern of which is approximately the same as the hole pattern of the hydraulic machine-side orifices of the connector plate. 
     In one development, the likeness of the hole patterns relates at least to the through recesses of the control plate and to the connector recesses of the connector plate which are provided for the alternating pressure medium connection with the working spaces. 
     In one development, the orifices of the working spaces are arranged at least in sections on an identical pitch circle with those of the through recesses of the control plate. 
     If the through recesses penetrate the control plate parallel to the driveshaft, the hydraulic machine-side orifices of the connector recesses of the connector plate are also arranged at least in sections on the pitch circle in one development. 
     A hydrostatic unit, in particular a hydrostatic module, has a hydraulic machine which is configured in accordance with the preceding description, and a hydraulic attachment part, in particular a control valve, which is placed onto the connector plate and is connected mechanically and hydraulically to said connector plate via the first fastening means in a block-like manner, in other words without lines or pipes. 
     A unit/module which is very compact at least in the direction of the driveshaft of the hydraulic machine is formed by way of the block-like connection of the connector plate both to the attachment part and to the hydraulic machine. Here, the hydraulic connections are tight and rigid, as a result of which a reliability and efficiency of the unit is increased. 
     A particularly slim installation space is taken up if the hydraulic machine is arranged in alignment in the direction of the driveshaft via its connector plate with the attachment part. 
     In one development, the first fastening means have connecting bores which extend directly (that is to say, without deflection) from the attachment part, in particular from a block, into the control plate of the hydraulic machine. As a result, the hydraulic machine, in particular the hydraulic pump, can be operated at a higher rotational speed. In the case of the hydraulic pump, the reason for this is that an intake pressure at the associated working connector does not drop as a result of the direct connection to such a pronounced effect as in the case of a more indirect connection, for example by means of a hose. 
     In one development, the unit has a drive unit which is arranged, in particular flange-connected, on the hydraulic machine in alignment in the direction of the driveshaft. A sequence in said direction then results as follows: drive unit, hydraulic machine with connector plate, attachment part. Here, all the connections are preferably of block-like and therefore particularly rigid and tight configuration. 
     In one development, the unit also has a hydraulic consumer, for example a hydraulic cylinder, which can be supplied with pressure medium by the hydraulic machine and can thus be driven. A particularly slim installation space is also taken up here if all the abovementioned components are in alignment with one another. As an alternative to this, the consumer can of course be arranged parallel to or outside the alignment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In each case one exemplary embodiment of a connector plate according to the disclosure, a hydraulic machine according to the disclosure and a hydrostatic unit according to the disclosure is shown in the drawings. The disclosure will now be described using the figures of said drawings, in which: 
         FIG. 1  shows a hydrostatic unit in accordance with one exemplary embodiment in a perspective view, 
         FIG. 2  shows the hydraulic unit according to  FIG. 1  with a dismantled connector plate and axial piston machine, 
         FIG. 3  shows the hydrostatic unit according to  FIGS. 1 and 2  with a dismantled axial piston machine, 
         FIG. 4  shows the connector plate according to  FIGS. 1 and 3  in a perspective view, approximately from the direction of the axial piston machine, 
         FIG. 5  shows the connector plate according to  FIG. 4  in cross section, 
         FIG. 6  shows the connector plate of the preceding figures in a plan view, approximately from the direction of the attachment part, and 
         FIG. 7  shows the axial piston machine according to the preceding figures with a mounted connector plate. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a hydrostatic unit  1  having an electric drive unit  2 , a hydraulic machine  4  which is configured in a swash plate design as an axial piston machine, a connector plate  6 , an attachment part  8  which is configured as a control valve block, a hydraulic accumulator  10  and a hydraulic cylinder  12 . 
     The hydrostatic unit  1  can also be called an “autonomous axle”, since, in addition to the linearly acting hydraulic cylinder  12 , it also has the necessary components for driving it and supplying it with pressure medium, namely the drive unit  2 , the hydraulic machine  4  and the control valve block  8 . 
     It can be seen clearly here that the connector plate  6  is arranged in a sandwich-like manner between the hydraulic machine  4  and the control valve block  8  (attachment part). Here, the mechanical and fluidic connection of the connector plate  6  both to the hydraulic machine  4  and to the control valve block  8  is in each case of block-like configuration, that is to say without the necessity of hoses or pipes. In this way, the hydraulic machine  4 , the connector plate  6  and the control valve block  8  as one module form a compact, comparatively rigid construction which is simple in terms of apparatus technology. Here, the respective connection of the hydraulic machine  4  to the connector plate  6  and of the control valve block  8  to the connector plate  6  can be called “of block-like configuration”. 
     In the exemplary embodiment which is shown, the arrangement of the drive unit  2 , the hydraulic machine  4 , the connector plate  6  and the control valve block  8  is “in line”, in principle parallel to the drive axis (not shown) of the hydraulic machine  4 . 
       FIG. 2  shows the hydrostatic unit  1  in a view in the direction of the arrow in accordance with  FIG. 1 , that is to say approximately from the view of the drive unit  2  or the hydraulic machine  4 , the drive unit  2 , the hydraulic machine  4  and the connector plate  6  being dismantled. The view of a connector face  14  of the valve control block  8  is therefore revealed. Here, the connector face  14  is of substantially planar configuration and has a connector hole pattern  16  with two working connectors A, B and a leakage connector L. 
     In order to seal the connector plate against the attachment part, in each case one groove, in particular a rectangular groove, is provided in each case radially outside the connectors A, B, L of the attachment part, in each case around the full circumference of the latter. A seal ring with a round cross section (O-ring) or a rectangular cross section (R-ring) can be arranged, in particular is arranged, in said groove. 
     As an alternative, the grooves which were mentioned above are arranged on that side or face of the connector plate which points toward the attachment part. 
     As an alternative, hybrid forms are possible, in which at least one groove, in particular with a seal ring, is arranged on the side of the attachment part and at least one groove, in particular with a seal ring, is arranged on the side of the connector plate. 
     Furthermore, the connector face  14  has a fastening hole pattern  18  with four blind bores  20  which are provided in a rectangular arrangement and, in relation to a center point between the working connectors A, B, are situated away from them, radially outside them. A rectangle which can be defined by the blind bores  20  has axes of symmetry  22  and  24 , the two working connectors A, B being arranged on the axis of symmetry  24 , and the leakage connector L being arranged on the axis of symmetry  22 . Here, a center point of the leakage connector L lies approximately on an imaginary connecting line of two blind bores  20  of one longitudinal side of the rectangle. 
       FIG. 3  shows the hydrostatic unit  1  in accordance with  FIG. 2  with a mounted connector plate  6 . In relation to  FIG. 2 , it can be seen clearly that first fastening screws  26  which penetrate the connector plate  6  are provided in congruence with the blind bores  20  in accordance with  FIG. 2 . Said first fastening screws  26  engage through threadless through bores (not shown) of the connector plate  6  and are screwed into the blind bores  20  in accordance with  FIG. 2  which have an internal thread. In this way, the connector plate  6  is mechanically and fluidically connected to the control valve block  8  in a compact and rigid manner. The first fastening screws  26  with the through recesses which are concealed by them in  FIG. 3  therefore represent first fastening means  28  which belong to the connector plate  6  and serve for the block-like (that is to say, hose-free or pipe-free) connection of the control valve block  8  to the connector plate  6 . 
     Furthermore, thread run-outs of fastening screws  30  which penetrate through bores  32  of the connector plate  6  can be seen in  FIG. 3 . Accordingly, the respective screw head is situated on the side which faces away from the observer, that is to say facing the connector face  14  of the control valve block  8 . Here, the through recesses  32  are likewise of threadless configuration. The fastening screws  30  together with the through bores represent second fastening means  34 , via which a housing  72  of the hydraulic machine  4  in accordance with  FIG. 1  can be attached to the connector plate  6 . 
     The second fastening means  34  therefore make the block-like connection in a mechanical and hydraulic way of the hydraulic machine  4  to the connector plate  6  possible, which connection likewise proves to be rigid and compact. 
     Furthermore,  FIG. 3  shows that the connector plate  6  is penetrated by connector recesses A′, B′ which have kidney-shaped orifices  38 ,  40  on one side  36  of the connector plate  6 , which side  36  points toward the hydraulic machine. Here, the orifices  38 ,  40  have approximately the shape of correspondingly kidney-shaped through recesses of a control plate (cf.  104 ,  FIG. 7 ) of the hydraulic machine  4 . Here, the orifices  38 ,  40  run approximately on a pitch circle, on which center points of the working connectors A, B of the control valve block  8  in accordance with  FIG. 2  are also arranged. 
     Furthermore,  FIG. 3  shows that the connector plate  6  has a bearing seat  42  for a drive shaft (cf.  82 ,  FIG. 7 ) of the hydraulic machine  4 , which bearing seat  42  is arranged centrally in relation to the connector recesses A′, B′ and the fastening means  28 ,  34 . 
     Approximately in the region of dead centers between the orifices  38 ,  40  of the connector recesses A, B′, in each case one substantially droplet-shaped leakage duct  44 ,  46  is configured on both sides of the bearing seat  42 , which leakage duct  44 ,  46  is in pressure medium connection with the bearing seat  42 . Here, the leakage ducts  44 ,  46  are configured as recessed pressure pockets in the material. Here, a leakage bore  48  leads as a through bore out of the leakage duct  46 , which leakage bore  48  is in pressure medium connection with the leakage connector L in accordance with  FIG. 2  of the control valve block  8 . Here, the two leakage ducts  44 ,  46  are connected fluidically via an annular and groove-shaped leakage duct  50  which extends concentrically, radially outside the connector recesses A′, B′. 
       FIG. 4  shows the connector plate  6  in accordance with the preceding figures in a perspective view, as results from  FIG. 1  but tilted toward the observer to a somewhat greater extent. It can be seen as additional information, in particular, that the view, for example, through the hydraulic machine-side orifice  38  through the hydrostatic connector recess A′ as far as the orifice on the other side which is situated on the connector plate  6  on the attachment part-side is free. It is accordingly shown that the connector recesses A′, B′ have kidney-shaped orifices  38 ,  40  on the hydraulic machine side and circular orifices toward the control valve block  8 . The latter are approximately congruent with the working connectors A, B in accordance with  FIG. 2  of the control valve block  8 . 
     Furthermore, an edge-side, secondary leakage connector L′ can be seen on a longitudinal side  52  which is adjacent with respect to the leakage duct  46 . Said secondary leakage connector L′ branches off from the leakage through bore  48  approximately at a right angle laterally toward the outside to the longitudinal side  52 , out of which it opens. A cross section which is defined by the plane of symmetry A-A in accordance with  FIG. 4  gives an insight into the geometric configuration of said secondary leakage connector L′ and the connector plate  6 . Here, the plane of symmetry is defined by the axis of symmetry  22  in accordance with  FIG. 3  in a direction perpendicularly with respect to the side  36 . 
     In addition, a seal groove  56  which encompasses the orifices  38 ,  40  and the leakage ducts  44 ,  46  in a circular manner and radially on the outside can be seen clearly in  FIG. 4 . Here, in the assembled state, a seal ring is inserted, for example an O-ring ( 90 , cf.  FIG. 7 ), via which seal ring a housing of the hydraulic machine  4  is shut off in a fluidtight manner against the connector plate  6 . The abovementioned through bores  29  of the first fastening means  28  can be gathered as further information from  FIG. 4 , through which through bores  29  the first fastening screws  26  penetrate, in order to fasten the connector plate  6  to the control valve block  8  by means of the blind bores  20  with an internal thread which are provided there. 
       FIG. 5  shows the section A-A in accordance with  FIG. 4 . Here, the connector plate  6  extends with a vertical axis  58  parallel to the driveshaft of the hydraulic machine, and has a lower height than width or length. In relation to  FIGS. 3 and 4 , the bearing seat  42  extends as a pocket-shaped recess with a rounded bottom in a rotationally symmetrical manner about the vertical axis  58 . Toward its open side, the bearing seat  42  is widened radially in a stepped manner via radial shoulders  60 ,  62  and  64 . Here, the shoulder represents an axial support for an anti-friction bearing (cf.  88 ,  FIG. 7 ) of the drive shaft  82 , and an inner circumferential face of the bearing seat  42 , which cylindrical inner circumferential face extends between the shoulders  62  and  64 , represents a radial support for the anti-friction bearing of the drive shaft  82  of the hydraulic machine  4 . 
     In the section A-A, the leakage ducts  44 ,  46  and the circumferential leakage duct  50  which opens laterally into them can be seen clearly. In accordance with the right-hand side of  FIG. 5 , the leakage through recess  48  can be seen, which penetrates the connector plate  6 , starting from the bottom of the leakage duct  46  as far as a leakage orifice L on the side  68 . Approximately halfway up in relation to the vertical axis  58 , the secondary leakage connector L′ branches off from the leakage through recess  48  radially to the outside, towards the longitudinal side  52  of the connector plate  6  (cf.  FIG. 4 ). 
     Furthermore,  FIG. 5  shows that the leakage duct  46  extends radially to the inside to the shoulder  64  and drops downward in a base-shaped manner (that is to say in the direction of the bearing seat  42 ) on the other side of the leakage through bore  48 . In this way, the bearing seat  42  is also connected fluidically to the leakage connectors L, L′. 
     The secondary leakage connector L′ is connected to the leakage through bore  48  via a throttle point  66  of tapered cross section. One side  68  of the connector plate  6 , which side is directed toward the attachment part  8 , is of planar configuration. 
       FIG. 6  shows the connector plate  6  in accordance with the preceding figures in a view as afforded from the attachment part  8  (control valve block). The through bores  29 ,  32  of the first and second fastening means can be seen again, as can the connector recesses A′, B′ and the leakage through recess  48  or the leakage connector L. The secondary leakage connector L′ is indicated on the right-hand side in  FIG. 6 . 
     It can be seen as additional information in  FIG. 6  that the second through bores  32  are configured in each case as a stepped bore and in each case have a step  70  which is recessed in comparison with the side  68 . 
     In the mounted state of the connector plate  6 , a screw head of the second fastening screws  30  (cf.  FIG. 3 ) dips into said step  70 . 
     The screw head (not shown here) terminates flush with the side  68  of the connector plate  6 , or the step  70  is configured so as to be so deep that the screw head is even recessed below the side  68 , that is to say does not protrude beyond said side  68 . 
     As a result, the connector plate  6  can be mounted or is mounted with its side  68  in a planar manner on the connector face  14  in accordance with  FIG. 3  of the attachment part  8 . 
     Therefore, both the second fastening screws  30 , the second through bores  32  and the steps  70  belong to the second fastening means  34 . 
       FIG. 7  shows the hydraulic machine  4  including the connector plate  6 . The hydraulic machine  4  is configured as an axial piston machine of swash plate design. It has a substantially pot-shaped housing  72  with a housing bottom  74  and a housing opening  76 . The housing opening  76  is closed by the connector plate  6 . A housing flange  78  is configured on the housing bottom  74  radially on the outside, which housing flange  78  has a plurality of through bores  80 , via which the hydraulic machine  4  can be connected to the electric drive unit  2  in accordance with  FIG. 1 . Here, the connection preferably takes place via anti-fatigue screws. 
     The hydraulic machine  4  has a drive shaft  82  with a splined shaft stub  84  which can be coupled to the electric drive unit  2 . The drive shaft  82  is mounted rotatably via anti-friction bearings  86 ,  88  firstly on the housing bottom  74  and secondly on the bearing seat  42  of the connector plate  6 . Here, the connector plate  6  is connected in a block-like manner to the housing  72 . Here, the connection takes place via the second fastening means  34  of the connector plate  6 , that is to say via the second through bores  32  in accordance with  FIG. 6 , into which, in accordance with  FIG. 3 , the second fastening screws  30  are inserted and are screwed into threaded bores (not shown) of the housing  72 . Said screw connection is not shown in  FIG. 7 . An O-ring  90  is inserted into the seal groove  56  in order to seal the interior space of the housing  72  on the connector plate  6 . 
     The hydraulic machine  4  has a cylinder barrel  92  which is connected fixedly to the drive shaft  82  so as to rotate with it and in which cylinder bores  96  are made in a circumferentially distributed manner parallel to a longitudinal axis  94  of the drive shaft  82 . Working pistons  98  are guided axially displaceably in said cylinder bores  96 , feet of the working pistons  98  being supported in a sliding manner on a swash plate  100  via pads. A working stroke of the working pistons  98  is thus produced in a known way upon rotation of the drive shaft  82 . 
     The cylinder bores  96  have end-side orifices  102  toward the connector plate  6 . A control plate  104  with kidney-shaped through recesses A″, B″ is arranged between an end side of the cylinder barrel and the connector plate  6 . Here, the orifices of the latter which point toward the connector plate  6  have the same kidney-shaped form as the orifices  38 ,  40  of the connector plate  6  (cf., for example,  FIG. 4 ). Upon rotation of the drive shaft  82 , the orifices  102  of the working spaces therefore sweep over the orifices of the through recesses A″, B″ of the control plate  104 , as a result of which the connector recesses A′, B′ pass into alternating pressure medium connection with the working spaces  96 . 
     A closure plate is disclosed having two parallel connector sides, in each case for a hydraulic machine and an attachment part. Here, the connector plate has fastening means for the mechanical and fluidic connection to at least the attachment part, which fastening means are configured in such a way that the attachment part can be connected in a block-like manner. Furthermore, a hydraulic machine having the connector plate is disclosed, said connector plate being connected in a block-like manner to a housing of the hydraulic machine. A hydrostatic unit at least comprising a hydraulic machine and an attachment part is also disclosed, the two components being connected in a block-like manner via the connector plate, in line or in alignment with the driveshaft of the hydraulic machine. 
     LIST OF DESIGNATIONS 
     
         
           1  Hydrostatic unit 
           2  Drive unit 
           4  Hydraulic machine 
           6  Connector plate 
           8  Control valve block 
           10  Hydraulic accumulator 
           12  Hydraulic cylinder 
           14  Connector face, attachment part 
           16  Connector hole pattern, attachment part 
           18  Fastening hole pattern, attachment part 
           20  Blind bore 
           22 ,  24  Axis of symmetry 
           26  First fastening screw 
           28  First fastening means 
           29  First through bore 
           30  Second fastening screw 
           32  Second through recess 
           34  Second fastening means 
           36  Side 
           38 ,  39 ,  40  Hydraulic machine-side orifice 
           42  Bearing seat 
           44 ,  46  Leakage duct 
           48  Through bore, leakage duct 
           50  Leakage duct 
           52  Longitudinal side 
           54  Plane of symmetry 
           56  Seal groove 
           60 ,  62 ,  64  Shoulder 
           66  Throttle point 
           68  Side 
           70  Step 
           72  Housing 
           74  Housing bottom 
           76  Housing opening 
           78  Flange 
           80  Through bore 
           82  Drive shaft 
           84  Shaft stub 
           86 ,  88  Anti-friction bearing 
           90  O-ring 
           92  Cylinder barrel 
           94  Longitudinal axis 
           96  Cylinder bore 
           97  Working space 
           98  Working piston 
           100  Swash plate 
           102  Orifice 
           104  Control plate 
         A, B Working connector 
         L, L′ Leakage connector 
         A′, B′ Hydrostatic connector recess 
         A″, B″ Through recess