PRIOR ART: From US 4,934,253 it is prior known to adapt a pump to operate with either direction by means of a two part housing, including a housing part and a connection part.

This latter part can be mounted in two alternative positions turned substantially through 180° about the centre axis of the axial piston engine. The connecting piece according to the known device is provided with four connecting holes adapted to be positioned coaxially with corresponding holes in the housing part which results in that the two alternative positions are exactly displaced relative to each other by 180°. This limits the possibilities to design the prior known pump with optimal performance with regard to capacity.

THE PRESENT INVENTION: The object of the present invention is to provide a hydraulic rotating axial piston engine of the above discussed type having increased capacity in either direction of rotation.

The present object is obtained by means of an engine according to the present invention, which is characterized

according to the characterizing part of the accompanying claim 1.

BRIEF DESCRIPTION OF DRAWINGS: The invention will now be described in more detail with reference to a preferred embodiment shown in the drawings, in which Fig. 1 shows a side view of a pump according to the present invention, Fig. 2 is an end view of the pump, Fig. 3 is an axial section of the pump, Fig. 4 is a plan view of a connecting part of the pump as seen separately from the inside, Fig. 5 is an end view of a modified embodiment of a housing part of the pump according to Fig. 1 and Fig. 6 is an end view of the connecting part of the pump, showing two alternative turning positions of the connecting part.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT: The hydraulic rotating axial piston engine according to the present invention is shown as an embodiment in Fig. 1 and 2 as an axial piston pump 1 having a housing 2 which is comprised by at least two parts, in the shown example three parts, namely a housing part 3 and a connecting part 4, having connecting openings, namely an inlet opening 5 and an outlet opening 6 for connecting input and output conduits for hydraulic fluid to the pump. A third part 7 of the housing is a support part for the input shaft 8 which is provided to be connected with a drive motor, not shown.

In Fig. 3 the general parts of the pump are shown. The pump is of a so called bent axis type, having a rotational axis

9, forming a rotational axis for the input shaft 8 and a second rotational axis 10 inclined relative to the first axis by an angle of for example 40°. The second rotational axis is an axis for a cylinder barrel 11 which is rotatably journalled in the housing. The cylinder barrel 11 has a number of axially extending pistons 12, movable axially, i. e. substantially in parallel with the axis 10 in a reciprocating movement in a corresponding number of cylinders 13, also extending axially with the axis 10, and circumferentially equally spareced along a circle line 14, see Fig. 5. Each cylinder 13 has a fluid passage 15 with a port 16 in the planar end surface 17 of the cylinder barrel 11. Each opening 16 has its largest length along the peripheral circle line 14 and are kidney-shaped. From Fig.

3 it is further apparent that each piston 12 has a piston rod 18 having spherical heads 19, supported in spherical bearing surfaces, forming recesses 20 in a swash plate 21 which forms an integral part of the input shaft 8. The spherical recesses 20 are rotatably around a radial plane which is angled relative to the radial plan of the cylinder barrel 11 which results in the reciprocating movement of the pistons 12 and the pumping action according to a prior known principle, in order to create vacuum i. e. suction in the inlet openting 5 and pressure in the outlet opening 6, see for example US patent No. 5,176,066. Synchronizing means are arranged in order to synchronize the rotational movements of the cylinder barrel with the rotation of the swash plate 21. In the shown example the synchronizing means are made in the form of tooth gear formed by a tooth wheel rim 22 on the cylinder barrel cooperating with a tooth wheel 23 of the input shaft 8. A support pin 24 supports the cylinder barrel along the axis 10 cooperating with a shaft 25 which forms the rotational axis 10 and projects through a bore 26 of the cylinder barrel and supported in a bore 26'of the connecting piece 4 of the housing.

Fig. 4 shows the connecting part 4 of the housing separately and from the inside. The connecting part 4 has on its inside a substantially planar, circular surface 27 which in the mounted position is faced to the planar surface 17 of the cylinder barrel 11. The two planar surfaces 17,7 are arranged to contact each other with a sealing fit. On its inside the connecting part 4 is provided with one inlet port 28 and one outlet port 29, which are kidney-shaped. The inlet port 28 communicates through a channel with the inlet opening 5 and the inner outlet opening 29 communicates through a separate channel with the outlet opening 5 on the outside of the connecting part 4. The inlet and outlet port 28,29 extend along a peripheral circle line 30 which has a corresponding radius as the circle line 14 of the openings 16 of the cylinder barrel 11. The inlet and outlet opening 28,29 extend on each half of said circle line 30, separated by a main plane 31 extending through the connecting part 4. The inlet and outlet port 28,29 are further divided by a second main plane 32 extending 90° relative to the first main plane 31.

One of these main planes is normally a symmetrical plane for the connecting part 4. The inlet and outlet port 28,29 further extend along the circle line 30 along a predetermined peripheral angle which in the shown example is somewhat larger for the inlet opening 5 than for the outlet opening 6 and are arranged so that simultaneously more than one cylinder port 16 communicate with the inlet port 28 and the inner outlet port 29 respectively.

According to the present invention the connecting part 4 of the housing 2 is arranged to be mounted in at least two alternative positions in order to enable the pump to be operated by rotating the input shaft in two alternative directions of rotation. According to the present invention it has been discovered that the flow capacity of the pump can be increased by extending the kidney-shaped inlet port

28 of the connecting part 4 in the chosen rotational direction of the cylinder barrel so that the cylinder ports 16 are open to the kidney-shaped inlet port 28 even when the corresponding piston 12 passes its lower dead centre U. D. C. According to the present invention this is accomplished by the two alternative mounting positions of the connecting part 4 deviate from each other by a relative turning angle a = 6°-30°, alternatively ß = 186°-210° (a + 180°) so that the kidney-shaped ports 28,29 are displaced a predetermined extent in the rotational direction. This is practically accomplished by enabling the fastening means 33,34,35,36 between the connecting part 4 and the housing part 3 to fasten the connecting part in at least two alternative positions, so that the connecting part can be displaced according to the above intervals.

Main plane 37 is defined by the upper and lower dead centers of the pistons and main plane 31 is corresponding to this. Consequently the main planes 31,32 can be in two alternative positions displaced by substantially half of the above intervals relative to the two main planes 37,38 defined for the housing part, see Figs. 5 and 6. Main plane 38 extends 90° relative to main plane 37. Fig. 6 shows the different mounting positions of the connecting part 4. All main planes 31,32,37,38 are crossing in the rotational axis of the cylinder barrel 11. The fastening means 33-36 are practically screws extending through two alternative sets of holes 39-42 and 43-46 respectively in the connecting part 4 and one set of holes 45-48 in the housing part 3, as senn in Fig. 4 and 5, or reversely, as seen in Fig. 6. Consequently in the embodiment of Fig. 6 the connecting parts 4 has one set of holes 39'-42'and the housing part 3 has two sets of holes (not shown). In the embodiment as shown in Fig. 2 the fastening means 33-36 with their alternative sets of holes 39-42 and 43-46 lack symmetry with respect to their mutual positions in the connecting part as well as the housing part 3. This

involves that merely two alternative positions are possible. In the modified embodiment shown in Fig. 4-6, all holes are symmetrical with respect to their mutual positions. This involves that four alternative positions are possible. Alternatively the double holes can be replaced by oblong holes enabling that the connecting part can be positioned in a large number of positions within the defined angular intervals.

In the above embodiments the engine has been described as a pump, having an input shaft for a motor. The same principle can be used for an engine acting as a motor, driven by a hydraulic fluid, whereas the shaft 8 acts as an output shaft for driving a rotating engine, for example a drilling engine.