Rotary axial piston machine with hydrostatic pressing device seal arrangement

Abstract

A hydrostatic axial piston machine includes a pressing pressure chamber for the cylinder drum which is supplied with pressing pressure from a circular-arc-like elongate hole of a distributor plate or from a plurality of connection channels of the cylinder drum. The pressing pressure chamber is delimited radially outwardly by the cylinder drum and radially inwardly by the drive shaft. The pressing pressure chamber is delimited axially at both sides by seals which are both arranged between the radially inner rotating drive shaft and a radially outer stationary component. The radially outer component may be the cylinder drum or, in the case of the distributor-plate-side seal, also a gap seal between the drive shaft and a bearing bush of the distributor plate. Both seals are arranged at the distributor plate side with respect to a tooth arrangement or a retraction ball.

Claims

1. A hydrostatic axial piston machine, comprising: a plurality of pistons; a cylinder drum in which the plurality of pistons are guided; a swash plate to which the plurality of pistons are coupled; a drive shaft coupled to the cylinder drum in a rotationally secure manner; and a hydrostatic pressing device that tensions the cylinder drum against a stationary distributor plate, the hydrostatic pressing device having a pressing pressure chamber delimited by the drive shaft and the cylinder drum and which is delimited by a swash-plate-side seal and a distributor-plate-side seal, wherein both the swash-plate-side seal and the distributor-plate-side seal are directly in abutment with the drive shaft, and the swash-plate-side seal is arranged directly between the drive shaft and the cylinder drum.

2. The axial piston machine according to claim 1, further comprising: a tooth arrangement formed between the drive shaft and the cylinder drum, wherein both the swash-plate-side seal and the distributor-plate-side seal are arranged at a distributor plate side of the tooth arrangement.

3. The axial piston machine according to claim 2, wherein both the swash-plate-side seal and the distributor-plate-side seal have a sealing diameter that is smaller than a root diameter of the tooth arrangement.

4. The axial piston machine according to claim 3, wherein the sealing diameter of the distributor-plate-side seal is smaller than the sealing diameter of the swash-plate-side seal.

5. The axial piston machine according to claim 1, wherein the distributor-plate-side seal is arranged directly between the cylinder drum and the drive shaft.

6. The axial piston machine according to claim 1, wherein the distributor-plate-side seal is arranged between the distributor plate and the drive shaft.

7. The axial piston machine according to claim 1, wherein the distributor-plate-side seal is a sealing ring.

8. The axial piston machine according to claim 1, wherein the distributor-plate-side seal is a gap seal on a bearing bush, and the drive shaft forms a through-drive at the distributor plate side.

9. The axial piston machine according to claim 1, further comprising: a pressure medium connection between a circular-arc-like elongate hole of the distributor plate, which is acted on with high pressure, and the pressing pressure chamber includes a radial groove of the distributor plate, an annular groove of the distributor plate, and at least one axial channel of the cylinder drum that is directly connected to the annular groove.

10. The axial piston machine according to claim 1, further comprising: a pressure medium connection between a circular-arc-like elongate hole of the distributor plate, which is acted on with high pressure, and the pressing pressure chamber includes a radial groove of the distributor plate, an intermediate space formed between the distributor plate and the drive shaft, and at least one axial channel of the cylinder drum that is directly connected to the intermediate space.

11. The axial piston machine according to claim 1, further comprising: a housing having a connection plate in which two main channels are defined; and a pressure medium connection between the two main channels and the pressing pressure chamber, the pressure medium connection including a shuttle valve connected at an input side to the two main channels and at an output side to an annular groove of the distributor plate, wherein the annular groove is directly connected to at least one peripheral axial channel of the cylinder drum.

12. The axial piston machine according to claim 1, wherein the cylinder drum includes a plurality of cylinders, the axial piston machine further comprising: a connection channel between each cylinder and a respective opening arranged at an end face of the cylinder drum; and a pressure medium connection between a plurality or all of the connection channels and the pressing pressure chamber includes a non-return valve arrangement arranged in the cylinder drum.

13. The axial piston machine according to claim 12, wherein the non-return valve arrangement has a plurality of non-return valves, each of which connects a cylinder or connection channel to the pressing pressure chamber.

14. The axial piston machine according to claim 12, wherein: each connection channel is connected via a connection branch channel and a branch channel opening to the pressing pressure chamber; and the non-return valve arrangement has a resilient ring arranged on the outer periphery of the pressing pressure chamber, the resilient ring configured to abut the branch channel openings and to be raised from the branch channel openings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A plurality of embodiments of an axial piston machine according to the disclosure are illustrated in the Figures, in which:

(2) FIG. 1 is a schematic longitudinal section of an axial piston machine according to the prior art, on which the pressing pressure chambers of the following embodiments can be provided,

(3) FIG. 2 is a longitudinal section of a portion of the axial piston machine according to the disclosure according to a first embodiment,

(4) FIG. 3 is a view of a distributor plate from FIG. 2,

(5) FIG. 4 is a longitudinal section of a portion of the axial piston machine according to the disclosure according to a second embodiment,

(6) FIG. 5 is a view of a distributor plate from FIG. 4,

(7) FIG. 6 is a longitudinal section of a portion of the axial piston machine according to the disclosure according to a third embodiment,

(8) FIG. 7 is a schematic view of a distributor plate and a connection plate from FIG. 6,

(9) FIG. 8 is a view of a cylinder drum according to a fourth embodiment, and

(10) FIG. 9 is a longitudinal section of a portion of the axial piston machine according to the disclosure according to a fifth embodiment.

DETAILED DESCRIPTION

(11) FIG. 1 is a schematic, sectioned view of significant components of an axial piston machine of the swash plate construction type. A cylinder drum 1; 101; 201 is coupled to a drive shaft 2 in a rotationally secure manner by means of a tooth arrangement 3 so that they rotate together. Along the drive shaft 2, there extend in the cylinder drum 1; 101; 201 cylinders 4 which are distributed in a uniform manner over the periphery and in which pistons 6 are displaceably guided. Piston bases of the pistons 6 are coupled by means of sliding blocks 7 which rotate therewith in each case to a stationary swash plate 8 which is positioned in an oblique manner with respect to the drive shaft 2. Therefore, with each rotation about the drive shaft 2, each piston 6 carries out a stroke, the size of which is dependent on the oblique position of the swash plate 8.

(12) At the end face of the cylinder drum 1; 101; 201 opposite the swash plate 8 for each cylinder 4 there is provided an opening 10 which is connected to the respective cylinder 4 by means of a respective connection channel 11. The end face rotates and is tensioned with the peripheral openings 10 thereof against a stationary distributor plate 12; 112; 212; 312 which is secured to a connection plate 13 (merely indicated) of a housing (not illustrated in greater detail) of the axial piston machine.

(13) The embodiments described below may be provided in the axial piston machine shown in FIG. 1 but cannot be seen in the illustration according to FIG. 1.

(14) FIG. 2 is a longitudinal section of a portion of the axial piston machine according to the disclosure according to a first embodiment. The distributor-plate-side region of the drive shaft 2 and a side of the cylinder drum 1 are illustrated. The cylinder drum 1 is (in FIG. 2 on the right) pressed against the distributor plate 112 by the high pressure in the cylinders 4. In order to homogenize and increase this pressing force acting at one side, there is provided a pressing pressure chamber 14 which is delimited radially inwardly by the drive shaft 2 and radially outwardly by the cylinder drum 1. When viewed axially along a rotation axis 16 of the drive shaft 2 and the cylinder drum 1, the pressing pressure chamber 14 is delimited at one side by a seal 18 at the tooth arrangement side or swash plate side and, at the other side, by a distributor-plate-side seal 20 (the swash plate is arranged on the left in FIG. 2 and only illustrated in FIG. 1).

(15) From the swash plate in the direction toward the distributor plate 112 (in FIG. 2 from left to right) there are provided along the rotation axis 16 first the tooth arrangement 3 having a root diameter D.sub.3, then a diameter decrease of the drive shaft 2 to a sealing diameter D.sub.18, on the outer periphery of which the swash-plate-side seal 18 which is constructed as an O-ring is arranged, then another diameter reduction of the drive shaft 2 to a sealing diameter D.sub.20, on the outer periphery of which the distributor-plate-side seal 20 is arranged. The diameter difference D.sub.18-D.sub.20 of the two seals 18, 20 defines a differential surface-area which inside the cylinder drum 1 acts thereon as a pressing force in the direction toward the distributor plate 112 (in FIG. 2, from left to right).

(16) According to the disclosure, both seals 18, 20 are pushed onto the illustrated end of the drive shaft during the assembly of the sub-assembly shown together with the cylinder drum 1 (in FIG. 2, from right to left). In this instance, there is also no contact of the swash-plate-side seal 18 with the tooth arrangement 3. Since no additional component, such as, for example, a retraction ball, is also affected by the pressing pressure chamber 14, no additional seals are also necessary.

(17) FIG. 3 is a view (according to FIG. 2 from left to right) of the distributor plate 112 of the first embodiment from FIG. 2. Since, in the axial piston machine shown, no pressure side change is required, one of two circular-arc-like elongate holes 22 is always acted on with high pressure HD. Radially inside the two elongate holes 22, an annular groove 24 extending in a circular manner is introduced into the illustrated surface of the distributor plate 112 facing the cylinder drum 1. Furthermore, between the elongate hole 22 which is acted on with high pressure HD and the annular groove 24, a radial grove 26 is introduced into the illustrated surface of the distributor plate 112 facing the cylinder drum 1.

(18) FIG. 2 shows that the annular groove 24 of the distributor plate 112 is connected to an axial channel 28 of the cylinder drum 1. The axial channel 28 rotates together with the cylinder drum 1 about the rotation axis 16 and is consequently moved on a circular path along the annular groove 24. The axial channel 28 finally opens in the pressing pressure chamber 14. Consequently, a constant pressure medium connection of the elongate hole 22 which is acted on with high pressure HD to the pressing pressure chamber 14 is produced.

(19) FIGS. 4 and 5 show a second embodiment which is similar to the first embodiment according to FIGS. 2 and 3. Only the differences of the second embodiment with regard to the first embodiment are described below.

(20) Since the drive shaft 2 forms a through-drive 30 not only at the swash plate side, but also at the distributor plate side, the distributor-plate-side seal 120 is formed by a gap seal which is formed between a bearing bush 32 and the drive shaft 2, wherein the bearing bush 32 is inserted into the distributor plate 212 and into the connection plate 13.

(21) FIG. 5 shows that the radial groove 26 of the distributor plate 212 opens (instead of in an annular groove 24) in an intermediate space 124 which is formed between the drive shaft 2 and the distributor plate 212.

(22) FIG. 4 shows that this intermediate space 124 which extends in a circular manner over the entire periphery is delimited at one side (in FIG. 4, on the right) by the bearing bush 32, on the other side, the intermediate space 124 (in the same manner as the first embodiment according to FIGS. 2 and 3) is connected to the pressing pressure chamber 14 by means of an axial channel 28 which is formed in the cylinder drum 1.

(23) Finally, in the second embodiment according to FIGS. 4 and 5, another difference is that the axial channel 28 is not completely constructed in the cylinder drum, in a manner delimited radially inwardly by the drive shaft 2.

(24) The following three embodiments according to FIGS. 6 to 9 show possible ways of also always supplying the pressing pressure chamber 14 which is constructed according to the disclosure with high pressure HD when a pressure side change is possible with the axial piston machine.

(25) FIGS. 6 and 7 show a third embodiment, in which the pressure side change mentioned is possible. The cylinder drum 1 and the drive shaft 2 with the pressing pressure chamber 14 formed therebetween and the two seals 18, 20 correspond to those of the first embodiment according to FIGS. 2 and 3.

(26) In contrast to the first embodiment, the constant pressure medium connection to supply the pressing pressure chamber 14 with high pressure HD has two main channels 34 which extend through the connection plate 13 and which are connected to the pressing pressure chamber 14 via a shuttle valve 36 which is also integrated in the connection plate 13. More specifically, an output of the shuttle valve 36 is connected via a channel portion formed in the connection plate 13 and via a channel portion formed on the distributor plate 312 to an annular groove 24 according to the first embodiment (from FIGS. 2 and 3).

(27) FIG. 7 is a schematic illustration of a view of the distributor plate 312 with the elongate holes 22 thereof and the annular groove 24 together with the shuttle valve 36 which is arranged in the connection plate 13.

(28) FIG. 8 shows only the cylinder drum 101 with the drive shaft 2 of a fourth embodiment of the axial piston machine according to the disclosure as a sectioned illustration, wherein the axial piston machine is also configured for a pressure side change.

(29) Of the cylinders 4 which are distributed in a uniform manner over the periphery of the cylinder drum 101, only two are illustrated. It can be seen that the cylinders 4 are connected via a respective non-return valve 38 to the pressing pressure chamber 14 which is formed between the cylinder drum 101 and the drive shaft 2. In this instance, the non-return valves 38 may also be connected to the connection channels 11 (cf. FIG. 1).

(30) In this instance, it is sufficient for only a part-quantity of all the cylinders 4 which are distributed in a uniform manner over the periphery to be connected to the pressing pressure chamber 14 via such a non-return valve 38 in order to ensure that one of the cylinders 4 which are acted on with high pressure HD is always connected to the pressing pressure chamber 14 via the non-return valve 38 thereof.

(31) FIG. 9 shows significant components of a fifth embodiment of the axial piston machine according to the disclosure as also configured for the pressure side change. The cylinder drum 201 has for each connection channel 11 a connection branch channel 40 which extends in the direction toward the pressing pressure chamber 14. The corresponding branch channel openings which are formed on the inner periphery of the cylinder drum 201 are together covered by a resilient ring 42 which is tensioned radially outwardly. Consequently, there is formed a non-return valve arrangement which is simple in technical device terms and which ensures that only pressure medium from the cylinders 4 which are acted on with high pressure HD are always connected to the pressing pressure chamber 14 via the connection channels 11 thereof and the connection branch channels 40 thereof in order to supply the pressing pressure chamber 14.

(32) There is disclosed a hydrostatic axial piston machine having a pressing pressure chamber for the cylinder drum which is supplied with pressing pressure from a circular-arc-like elongate hole of a distributor plate or from a plurality of connection channels of the cylinder drum. The pressing pressure chamber is delimited radially outwardly by the cylinder drum and radially inwardly by the drive shaft. The pressing pressure chamber is delimited axially at both sides by seals which are both arranged between the radially inner rotating drive shaft and a radially outer stationary component. The radially outer component may be the cylinder drum or, in the case of the distributor-plate-side seal, also a gap seal between the drive shaft and a bearing bush of the distributor plate. Both seals are arranged at the distributor plate side with respect to a tooth arrangement or a retraction ball.

LIST OF REFERENCE NUMERALS

(33) 1; 101; 201 Cylinder drum 2 Drive shaft 3 Tooth arrangement 4 Cylinder 6 Piston 7 Sliding block 8 Swash plate 10 Opening 11 Connection channel 12;112;212;312 Distributor plate 13 Closure plate 14 Pressing pressure chamber 16 Rotation axis 18 Swash-plate-side seal 20; 120 Distributor-plate-side seal 22 Circular-arc-like elongate hole 24 Annular groove 26 Radial groove 28 Axial channel 30 Through-drive 32 Bearing bush 34 Main channel 36 Shuttle valve 38 Non-return valve 40 Connection branch channel 42 Resilient ring 120 Distributor-plate-side gap seal 124 Intermediate space D.sub.3 Root diameter D.sub.18 Sealing diameter D.sub.20 Sealing diameter D.sub.120 Sealing diameter HD High pressure ND Low pressure