Abstract:
The invention relates to a radial-piston hydraulic motor ( 10 ), having at least one cylinder groups ( 1 ) placed in a stationary position, which. cylinder groups contain piston mechanisms moving radially back and forth. A cam ring ( 12 ) is connected with a box frame ( 11 ) and the box frame with a distributor valve ( 13 ), which controls the pressurized fluid flow at the correct time into the cylinder spaces of the pistons that are at the power stage. The sense of rotation of the motor can be reversed by reversing the direction of flow of the fluid through the distributor valve ( 13 ). The fluid is passed to the distributor valve ( 13 ) through the sets of ducts in the shaft ( 14 ) which is placed in a stationary position together with the cylinder frame(s) ( 15 ) of at least one cylinder groups ( 1 ). The distributor ( 13 ) has a duct ( 31 ) which communicates with the power pressure and which is opened on the side face ( 13   a ) of the distributor ( 13 ). In this connection the force is applied, through the fluid at the power pressure, to the side face ( 13   a ) of the distributor ( 13 ).

Description:
FIELD OF THE INVENTION 
     The invention concerns a radial-piston hydraulic motor. 
     BACKGROUND OF THE INVENTION 
     From the prior art, solutions of radial-piston hydraulic motors are known in which a box frame is rotated and in which the box frame is connected with a distributor attached to the box frame. The distributor is a what is called distributor valve, which comprises bores placed parallel to the longitudinal axis of the distributor sleeve and opening on the front face of the distributor. Inlet ducts pass into the distributor, and outlet ducts pass out of the distributor. The inlet ducts open on the front face of the distributor, and so do the outlet ducts. The ducts at each particular time concerned in the distributor valve communicate alternatingly with pistons spaces, which piston spaces comprise pistons and press wheels connected with the pistons, said press wheels being fitted to move against a cam ring fitted in connection with the box frame. Thus, some of the pistons are in a power stage, and some are not. Pressurized medium is passed into the pistons that are at the power stage through the ducts in the distributor, and in a corresponding way, those pistons that have by-passed the power stage discharge fluid through the distributor through the outlet ducts in the distributor. The press wheels provided on the pistons press the cam ring provided on the box frame. The cam ring has a wave-formed shape, the cam ring and the connected box frame being rotated by means of the press wheels. In order that the distributor should operate as well as possible, the front face of the distributor must be in tight glide fitting against the front face of the cylinder frame, which cylinder frame comprises the ducts passing into the piston spaces. 
     In practice, it has been noticed that the pressurized fluid attempts to work/distort the distributor, and, thus, the contact on said front faces tends to deteriorate. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     In view of avoiding this problem; in the present patent application, it is suggested as a solution that the distributor comprises ducts which pass to its side face and which open in annular grooves on the side face of the distributor. In this way it is possible to avoid torques that distort the distributor by passing the force to the side faces of the distributor. The distributor preferably comprises bores passing into a first annular groove on the side face and into a second annular groove on the side face. The first annular groove communicates with the power pressure ducts, and the second annular groove communicates with the return ducts. However, when the sense of rotation of the motor is reversed, the functions of said ducts can be changed so that the power pressure ducts become return ducts, and the return ducts become power pressure ducts. Favourably, on the distributor, on its cylindrical face, there are seals between the annular grooves. Thus, leakage through the annular grooves is prevented. The seals have been fitted favourably at the ends of annular projection edges on the side face of the distributor in separate seal cavities, which are placed on the revolving box frame. The seals are composed of annular seals. 
    
    
     In the following, the invention will be described with reference to some preferred embodiments of the invention illustrated in the figures in the accompanying drawings, the invention being, yet, not supposed to be confined to said embodiments alone. 
     FIG. 1A is a sectional view of a radial-piston hydraulic motor in accordance with the invention. 
     FIG. 1B is an illustration of principle of the coupling and joint operation between the cam ring and the pistons. 
     FIG. 2 shows the area X subject of the present invention in connection with the distributor in FIG. 1A in an enlarged scale. 
     FIG. 3A shows the distributor viewed from the end. 
     FIG. 3B is a sectional view taken along the line I—I in FIG.  3 A. FIG. 3C is a sectional view taken along the line II—II in FIG.  3 A. The distributor comprises separate ducts passing to the side face of the distributor. 
     FIG. 4A shows an embodiment of the invention in which the pressure is applied to one pressure medium space V 1  only in connection with the side face of the distributor valve. 
     FIG. 4B shows the area A 10  out of FIG. 4A in an enlarged scale. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1A is a sectional view of a radial-piston hydraulic motor  10 . FIG. 2 shows the area X subject of the present invention out of FIG. 1A in an enlarged scale. The radial-piston hydraulic motor  10  comprises a rotated box frame  11 . The box frame  11  is connected with a cam ring  12 . In the embodiment shown in the figure, the box frame  11  is rotated, and the box frame is connected with a distributor  13  placed in a stationary position. The distributor  13  is a distributor valve, which comprises a number of axial bores e 1A ;e 2B , which communicate with the inlet duct e 1  and the outlet duct e 2  in the central shaft  14 . The distributor  13  revolves along with the box frame  11 , and the pressurized ducts e 1A  and the return fluid ducts e 2B  enter alternatingly into contact with the duct ends of the flow ducts  18   a   1 ,  18   a   2  . . . passing into the cylinder spaces p 1 ,p 2  . . . for the pistons  16   a   1 ,  16   a   2  . . . provided in the cylinder frame  15 . Thus, some of the pistons  16   a   1 ,  16   a   2  . . . in the cylinders are at a power stage, in which case the pressurized medium is passed through the distributor  13  into the cylinder spaces p 1 ,p 2  . . . and some of the pistons  16   a   1 ,  16   a   2  . . . are at an idle stage, in which case fluid is passed out of the cylinder spaces p 1 , p 2  of said pistons  16   a   1 ,  16   a   2  . . . through the distributor  13  into the outlet duct e 2 . The non-revolving cylinder frame  15  provided on the non-revolving central shaft  14  comprises a cylinder group  1 , and in the cylinder frame  15  there are a number of cylinder spaces p 1 ,p 2  . . . and a number of pistons  16   a   1 ,  16   a   2  . . . in said cylinder spaces. The piston  16   a   1 ,  16   a   2  . . . has been fitted to move in the piston space p 1 ,p 2  . . . by the effect of the fluid pressure introduced into said piston space. As is shown in the figure, each piston  16  comprises a press wheel  17   a   1 ,  17   a   2  . . . of circular section freely mounted on the top face of the piston. When the piston  16   a   1 ,  16   a   2  . . . is pressed with force against the wave-shaped face  12   a  of the cam ring  12 , the cam ring  12  and the connected box frame  11  and the distributor valve  13  connected with the box frame  11  can be made to revolve. Through the ducts  31  and  32 , a pressurized medium is passed into the groove V 1  and V 2  provided on the face  13   a  of the distributor  13 . In this connection, an annular radial power effect is produced in the grooves V 1 ,V 2 , and the distributor  13  is kept straight, and its front face f is sealed so that no lateral leakage of fluid occurs through the front face f. 
     The box frame  11  has been mounted to revolve on the bearings G 1  and G 2  in relation to the central shaft  14 . 
     In the figure, a spring is denoted with the letter J. By means of the spring, the front face of the distributor valve  13  is pressed against the front face of the cylinder frame  15 . The function of the spring J is, in the starting situation, to provide an initial force by whose means the dividing face between the parts  13  and  15  is kept tight. The shapes of the spaces U 1 , U 2  in the pressure ducts have been chosen so that, after a pressure has been generated in the ducts, the pressure acts upon the distributor valve  13  and presses it with a force axially against the front face of the cylinder frame  15 . 
     FIG. 1B is an illustration of principle of the interaction between the cam ring  12  and the pistons  16   a   1 ,  16   a   2 . Some of the pistons  16   a   1 ,  16   a   2  are at a power pressure, and some of the pistons have been connected through the distributor  13  to the side of the lower return pressure. 
     As is shown in FIG. 2, the distributor  13  comprises the ducts  31  and  32 . The ducts  31  communicate with the annular space U 1  between the central shaft  14  and the distributor  13  and with the annular groove V 1  on the side face of the distributor  13 . Further, the inlet duct e 1  passes into said annular space U 1 . The annular groove V 1  on the side face of the distributor has been sealed towards the sides by means of the seal N 1 , C 1  and N 2 , C 2 . Likewise, the annular space U 1  between the central shaft  14  and the distributor  13  has been sealed by means of the seals C 4  and C 5  provided on the shaft. Into the annular space U 1 , the pressurized medium, i.e. the power pressure, is passed through the duct e 1 . Out of the annular space U 1 , ducts e 1A  pass to the front face of the distributor and further to the pistons. The ends of the ducts e 1A  are denoted with the reference letters A in FIG.  3 A. The annular seals C 1 , C 2  and C 3  are placed in annular cavities O 1 , O 2  and O 3  in the box frame  11 . The seal rings N 1 , N 2  and N 3  proper of the seal extend into the cavities O 1 , O 2  and O 3 . What is concerned is a seal of two parts, which consists of an O-ring C 1 , C 2  and C 3  of rubber and of its support ring, i.e. a seal ring N 1 , N 2  and N 3 , which is favourably made of a teflon-bronze alloy. 
     The outlet duct e 2  is opened into the second annular space U 2  between the central shaft and the distributor, out of which space a duct  32  passes into the annular groove V 2  placed on the side face of the distributor. The annular groove V 2  has been sealed towards the sides by means of seals N 2 , C 2  and N 3 ,C 3  passing around the distributor. Out of the annular space U 2 , ducts e 2B  also open to the front face f of the distributor  13 , and through said ducts e 2B  the fluid that is displaced by the pistons  16   a   1 ,  16   a   2  that are not at a power stage is passed first into the annular space U 2  and further into the return duct e 2 . When the sense of rotation of the motor is reversed, the functions of the ducts are changed. The seals C 4 , C 5  and C 6  are placed on the shaft  14  in its grooves O 4 , O 5  and O 6 . The seals C 4  and C 5  are placed at both sides of the annular space U 1 , and the seals C 5  and C 6  are placed at both sides of the annular space U 2 , so that no leakage of fluid takes place towards the sides through the boundary faces between the distributor  13  and the shaft  14 . 
     FIG. 3A shows the distributor as viewed from ahead. FIG. 3B is a sectional view taken along the line I—I in FIG.  3 A. FIG. 3C is a sectional view taken along the line II—II in FIG.  3 A. 
     In FIG. 3A, the reference letters A denote the duct ends of the power pressure ducts e 1A  on the front face f of the distributor  13 . The ducts e 1A  open at the opposite end in the annular space U 1  between the central shaft  14  and the distributor  13 . The end openings of the return ducts e 2A  are denoted with the reference letters B. Said ducts e 2B  open in the annular space U 2  between the central shaft  14  and the distributor  13  and further in the return duct e 2 . 
     FIG. 3B is a sectional view taken along the line I—I in FIG.  3 A. As is shown in the figure, a duct e 1A  passes from the annular space U 1  in the distributor to the front face f of the distributor. Similarly, from the other annular space U 2 , which has been formed between the distributor  13  and the central shaft  14 , a return duct e 2B  passes to the front face f. 
     FIG. 3C is a sectional view taken along the line II—II in FIG.  3 A. As is shown in FIG. 3C, the ducts  31  open at opposite sides of the distributor  13  on the side face  13   a  of the distributor  13  in the first annular groove V 1  on the side face and, similarly, from the annular space U 2 , at opposite sides of the distributor, the ducts  32  open on the side face  13   a  of the distributor in the second annular groove V 2  on the side face  13   a.    
     In the embodiment illustrated in the figures above, the fluid at the power pressure has been passed into a groove V 1 , V 2  provided on the side face of the distributor which groove is defined both by the construction of the distributor and by the opposite backup face, which is composed of the box frame  11  in the embodiments described above. The box frame  11  has been connected with the distributor valve  13  so that the box frame  11  rotates the distributor valve  13 . Said coupling has been permitted by means of cotter pins  50 , which are illustrated in the figures above. Between the face T 1  of the box frame  11  and the face  13   a  of the distributor valve  13 , there is a glide fitting. Said arrangement permits application of a backup force against the distributor by passing a pressure into the grooves V 1 , V 2 . The cotter pin  50  transfers the rotation torque to the distributor valve  13 , in which connection the distributor valve  13  revolves while rotated by the box frame  11 . The play of the cotter pin, however, permits an axial movement of the distributor valve  13 , in which connection, by means of the spring force of the spring J and by means of hydraulic pressure, the distributor valve  13  can be pressed against the cylinder frame in order that a tight dividing face could be obtained. 
     Within the scope of the present invention, an embodiment as shown in FIGS. 4A and 4B is also possible, in which the groove V 2  has been formed in the same way as in the embodiments described above on the side face  13   a  of the distributor valve  13 , but the backup face is the inner face  60 ′ of a separate ring  60 . The ring  60  is placed freely on the face  13   a  of the distributor valve  13  between the shoulder  130  on the distributor valve  13  and the locking ring  70 . The seal construction is similar to that in the embodiments described above, and the ring  60  comprises seals N 1 , C 1  and N 2 , C 2  pressed against the distributor valve  13  and fitted in the grooves in the ring so as to seal the space V 2  towards the sides, while the space V 2  has, in this embodiment, been formed in the ring  60  on its inner face  60 ′. 
     In the embodiment shown in FIGS. 4A and 4B, the box frame  11  has been connected by means of cotter pins  80  with the locking ring  70 , while the locking ring  70  has been connected with the distributor valve  13  by means of pins  90 . The cotter pin  80  has been connected with the locking ring  70  with a loosely fitting glide fitting, in which case an axial movement between the distributor valve  13  and the connected locking ring  70  is permitted. The cotter pins  80  and  90  interconnect the parts  13 ,  70  and the box frame  11  so that the rotation torque is transferred to the distributor valve  13  from the box frame  11 . Thus, the distributor valve  13  revolves while rotated by the box frame  11  and along with the box frame. The ring  60  is placed freely with a glide fitting on the side face  13   a  of the distributor  13 . The space V 2  communicates with the pressurized fluid duct through the duct  32 . 
     In order that the distributor valve  13  could revolve reliably in relation to the central shaft and in order that there should not be any resistance to rotation, the locking ring  70  must be connected with the box frame  11  so that a certain radial movement is also permitted for the locking ring in relation to the central shaft  14 . Said radial movement is permitted so that a groove a 1  has been made into the locking ring  70 , into which groove a 1  a pin  90  has been fitted. The pin  90  is further connected with a pin hole a 2  in the distributor valve  13 . Thus, the locking ring  70  is kept axially in a stationary position in relation to the distributor valve  13 , but a certain radial movement is permitted for the locking ring. Thus, the locking ring  70  can position itself freely in a suitable radial position. On the other hand, by means of the cotter pin  80  between the locking ring  70  and the box frame  11 , an axial movement is permitted for the distributor valve  13 , but the locking ring  70  and the box frame  11  are kept radially immobile in relation to one another. By means of the cotter pin  80  passed through the holes b 1  in the locking ring  70 , the rotation drive and the torque are, however, transferred from the box frame  11  to the distributor valve  13 . 
     In the embodiment of the invention shown in FIGS. 4A and 4B, the pressurized medium is passed into one annular space V 2  only, which space has been fitted in the right-side end of the distributor, as shown in the figure. In practice, it has been noticed that this part of the distributor valve  13  is less rigid, in which case the greatest advantage is obtained from the arrangement in accordance with the invention so that the pressure space V 2  is placed in said portion of the distributor valve  13 . Thus, in the embodiment shown in FIGS. 4A and 4B, there is one groove V 2  only, which has been made onto the inner face  60 ′ of the ring  60  in this embodiment, and said groove communicates with the duct  32  and further with the rest of the system of ducts in the way shown in the figures. The embodiment shown in these figures can also be such that it is fully similar to the earlier embodiments, and, thus, there are two grooves, i.e. the grooves V 1  and V 2 , on the inner face  60 ′ of the ring  60 . The arrangement of supply of the pressure medium is similar to that of the earlier embodiment. FIGS. 4A and 4B, however, show a simplified embodiment, in which the supply of pressure has been arranged at the portion of the construction at which a compensation of forces is expressly needed.