Abstract:
In order to ensure that a radial piston engine ( 1 ) is not dismantled into the individual parts thereof during disassembly, a rotary cylinder ( 5 ) has a collar ( 19 ) on which the rotary cylinder is supported at the cam disk ( 2 ), wherein the cam disk ( 2 ) is connected to the housing ( 13 ) in such a way as to be torsion-proof and stationary.

Description:
[0001]    This application is a National Stage completion of PCT/EP2007/063111 filed Dec. 8, 2007 which claims priority from German patent application No. 10 2006 058 076.1 file Dec. 7, 2006 
     
    
       [0002]    The invention relates to a hydraulic radial piston engine 
       BACKGROUND OF THE INVENTION 
       [0003]    Hydraulic radial piston engines are used for example for driving a transmission of a concrete mixer on a truck, as disclosed in DE 10 2004 057 849 A1. In such cases a housing portion, in which a distributor is arranged, is bolted to a further housing portion, with a cam disk arranged between the two housing portions. A rotary cylinder, which in operation turns about a rotational axis, has radially positioned pistons which are in active connection with the cam disk and, in the operating condition, is supported by a bearing on the further housing portion. For servicing purposes the bolts which fix the housing portion and the rotary cylinder to the further housing portion are removed, and the hydraulic radial piston engine is dismantled from the concrete mixer truck in individual components. The complete assembly cannot be exchanged as a whole because when the bolts are removed, the hydraulic engine is no longer held together. 
         [0004]    FR 2 576 363 discloses a hydraulic radial piston engine in which the housing portion with the rotary cylinder and the further housing portion are connected as a structural unit to the rest of the transmission by bolts. This arrangement requires an additional housing plate between the transmission housing and the hydraulic engine, but this considerably increases the overall axial length. 
       SUMMARY OF THE INVENTION 
       [0005]    The purpose of the present invention is to provide a hydraulic engine which, for servicing purposes, can be exchanged as a structural unit, without increasing the overall axial length. 
         [0006]    This objective is achieved with a hydraulic radial piston engine of the type concerned. 
         [0007]    The hydraulic radial piston engine comprises a housing portion in which there is a hydraulic distributor and which is connected to the cam disk by connection means. The rotary cylinder has pistons arranged radially, which are connected to the cam disk. The cam disk is connected in a rotationally and positionally fixed manner to the housing portion by connection means, this connection remaining in place even in the dismantled condition. In the dismantled condition the rotary cylinder is supported along its rotation axis, in the direction opposite to that in which it is connected to the hydraulic distributor, on the cam disk. To enable this the rotary cylinder can comprise, on the side facing toward the distributor, a collar whose diameter is larger than the inside diameter of the cam disk, so that the collar can be brought to bear at least partially against the cam disk. 
         [0008]    In another embodiment the rotary cylinder can have, on the side facing toward the oil distributor, a groove into which a ring can be inserted, which can rest on one side against the rotary cylinder and on the other side against the cam disk. The hydraulic distributor has springs by which it is pushed toward the rotary cylinder. For servicing purposes, when the hydraulic radial piston engine is separated from the further housing portion the springs press the distributor against the rotary cylinder and the rotary cylinder is supported on the cam disk. Since the cam disk is connected to the housing portion, the hydraulic radial piston engine stays together as a structural unit. 
         [0009]    In a further embodiment this structural unit can additionally comprise a driveshaft on which the inner ring of a bearing is arranged, the driveshaft being formed in such manner that, at least in the axial direction, the inner ring of the bearing is held on the driveshaft while the driveshaft itself is held positionally fixed in the hydraulic radial piston engine. For that purpose the driveshaft can have a groove with a retaining ring which is supported on the surface upon which the distributor rests against the rotary cylinder, or else the driveshaft can have a collar which, as in the case of the retaining ring just described, is supported on the surface of the rotary cylinder. 
         [0010]    In another embodiment of the invention, the driveshaft can have a rod which passes through the housing portion in which the distributor is arranged, so that at least in the axial direction the driveshaft is supported on the housing portion. The rod can be made integrally with the driveshaft, but can also be in the form of a screw which is screwed into the driveshaft in order to hold the driveshaft, the inner ring of the bearing and the rotary cylinder in the direction of the distributor. For this purpose the housing portion in which the distributor is arranged or a housing portion connected thereto has a perforation through which the rod or screw passes through the housing portion concerned, to be connected to the driveshaft. The rod or screw is supported against the housing portion by a widened section. In one design form the screw can be removed in the assembled condition of the radial piston engine. 
         [0011]    Thus, for servicing purposes the radial piston engine can be separated from the rest of the housing without having to be stripped down to its individual components. 
     
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         [0012]    Other features emerge from the description of the figures, which show: 
           [0013]      FIG. 1 : Drive transmission for the drum of a concrete mixer truck with a hydraulic radial piston engine 
           [0014]      FIG. 2 : Section of the radial piston engine, with the rotary cylinder supported on the cam disk 
           [0015]      FIG. 3 : Radial piston engine with a driveshaft held by a bolt, and 
           [0016]      FIG. 4 : Radial piston engine with a driveshaft held by a rod 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]      FIG. 1 : A hydraulic radial piston engine  1  comprises a cam disk  2  which is in active connection with a rotary cylinder  5  via rollers  3  and pistons  4 , and the rotary cylinder  5  is connected in a rotationally fixed manner to a driveshaft  6 , and the driveshaft  6  is connected in a rotationally fixed manner to a sun gear  7 . Via planetary gears  8 , the sun gear  7  drives a ring gear  9  by which a drum (not shown) of a concrete mixer truck is rotationally driven. The axial force from the distributor  10  upon the rotary cylinder  5  is transmitted by a bearing  11  to a further housing portion  12 , which directly forms the housing of the step-down transmission and the supporting base. A housing portion  13  accommodates the distributor  10  and is connected in a rotationally and positionally fixed manner to the cam disk  2  by means of connecting elements such as bolts (not shown). In addition the housing portion  13  is connected, by other connecting means such as bolts (not shown), in a rotationally and positionally fixed manner to the further housing portion  12 , these bolts passing through the cam disk  2 . At the bearing  11 , the driveshaft  6  has a collar  14  against which the inner ring  15  of the bearing  11  rests in the axial direction. Instead of the collar  14 , a retaining ring can also be used. In addition, the driveshaft  6  is held on the rotary cylinder  5  in the axial direction by a retaining ring  16 . This ensures that when the radial piston engine is detached from the step-down transmission the inner ring  15 , the driveshaft  6  and the rotary cylinder  5  form a structural unit. The rotary cylinder  5  also has an abutment, shown in  FIG. 2 , on which the rotary cylinder  5  is supported against the cam disk  2 . Since the cam disk  2  and the housing portion  13  are connected and the rotary cylinder  5  is supported on the cam disk  2 , for servicing purposes the radial piston engine  1  can be taken off as a complete structural unit, namely comprising the housing portion  13 , distributor  10 , driveshaft  6 , inner ring  15 , rotary cylinder  5  and cam disk  2 , without having to strip down the radial piston engine  1  into its individual components. 
         [0018]    Between the housing portion  13  and the distributor  10  are arranged springs  21 , which press the distributor  10  against the rotary cylinder  5 . Thus, in the disassembled condition these springs push the rotary cylinder  5  against the cam disk  2 , whereby the rotary cylinder  5  remains in a fixed position relative to the cam disk  2 . When the radial piston engine  1  is mounted on the further housing portion  12  again, the rotary cylinder  5  is again pushed back by the bearing  11  against the spring force of the springs  21  and the rotary cylinder  5  no longer rests against the cam disk  2  in the axial direction. 
         [0019]      FIG. 2 : The rotary cylinder  5  has a groove with a retaining ring  17 , which secures a disk  18  in the axial direction. The disk  18  has a collar  19  which, in the disassembled condition of the radial piston engine  1 , rests on the inner curves of the cam disk  2  and so restricts the axial movement of the rotary cylinder  5  along its rotation axis  20 . Between the rotary cylinder  5  and the bearing  11  there can also be arranged a disk  22  for producing rotation speed pulses. 
         [0020]      FIG. 3 : The radial piston engine  1  in  FIG. 3  differs from the radial piston engine  1  shown in  FIG. 1 , in that the rotary cylinder  5  does not rest against the cam disk  2  via a collar  19  as in  FIG. 1 , but instead, to take off the radial piston engine  1 , a bolt  23  passes through the housing portion  13  and is screwed into the driveshaft  6 . The housing portion  13  can be made as a single part or in more than one part. With its head the bolt  23  rests against the housing  13 , so that the driveshaft  6  and with it the inner ring  15  and the rotary cylinder  5  are pulled in the direction of the distributor  10 . Since the cam disk  2  is connected to the housing portion  13  by connecting elements, the radial piston engine  1  can be detached from the step-down transmission without having to be stripped down to its individual components. After the radial piston engine  1  has been re-installed, the bolt  23  is removed so that the springs  21  again press the rotary cylinder  5  against the bearing  11 . The bolt  23  can then be used to connect the housing portion  13  to the further housing portion  12 . 
         [0021]      FIG. 4 : The radial piston engine  1  in  FIG. 4  differs from the radial piston engine  1  shown in  FIG. 3 , in that after the radial piston engine  1  has been mounted on the step-down transmission the screw  23  bolt remains in the radial piston engine  1  and rotates with it when the radial piston engine  1  is in operation. The screw  23  can have a screw head or a retaining ring as its contact surface, or it can be made as one piece with the driveshaft  6 . 
       INDEXES 
       [0000]    
       
           1  Radial piston engine 
           2  Cam disk 
           3  Rollers 
           4  Pistons 
           5  Rotary cylinder 
           6  Driveshaft 
           7  Sun gear 
           8  Planetary gears 
           9  Ring gear 
           10  Distributor 
           11  Bearing 
           12  Further housing portion 
           13  Housing portion 
           14  Collar 
           15  Inner ring 
           16  Retaining ring 
           17  Retaining ring 
           18  Disk 
           19  Collar 
           20  Rotational axis 
           21  Springs 
           22  Disk 
           23  Bolt 
           24  Retaining ring