EP1960665B1 - Hydrostatic piston machine comprising an initial starting flow in the direction of the periphery - Google Patents

Abstract

A hydrostatic piston machine with a cylinder drum, which is rotatably mounted in a housing, is provided. A plurality of cylinder bores are disposed in the cylinder drum, which bores can be connected via cylinder openings provided in the cylinder drum to a first control opening and a second control opening. The first control opening is connected to a low-pressure line and the second control opening to a high-pressure line. The first control opening is connected via a first connection and a second connection to a channel, wherein the first connection and, lying opposite, the second connection are disposed at the first control opening.

Description

The invention relates to a hydrostatic piston engine.

In a hydrostatic piston engine in whose housing a cylinder drum is rotatably arranged, the cylinder bores with a suction side and a pressure-side control kidneys are alternately connected, the maximum achievable speed is largely determined by the flow conditions at the entrance of the pressure medium from the suction-side control kidneys in the cylinder bores. Improvements in the fluidic boundary conditions, the inflow of the pressure medium can be improved in the cylinder drums on the suction side. However, due to the geometric conditions, such measures as increasing the flow-through cross-section by enlarging the opening in the cylinder drum or the surface of the suction kidney are just as limited as improving the Einströmfaktors for example by rounded edges. Please refer DE19521574 with the closest prior art.

From the DE 30, 18 711 C2 It is also known to add a tangential velocity component to the pressure medium on the suction side, whereby the occurrence of cavitation when reaching the speed limit is prevented. In order to produce a tangential velocity component, an impeller of a pump is arranged in a connection plate. The additional pump acts as an auxiliary pump. Your bike interacts with a collector. The collector is designed as a channel changing flow cross-section. The pressure medium entering the area of the control animals is composed of two components. On the one hand, accelerated pressure medium enters the control opening of the connection plate through the impeller. On the other hand, a part of the sucked by the impeller pressure medium is first fed into the collector and in a tapered portion of the collector back to the impeller where it experiences further acceleration before it also enters the control animals.

The described arrangement has the disadvantage that an additional pump is necessarily required, which gives the sucked pressure medium additional energy. The arrangement of the impeller in the axial extension of the shaft of the piston engine also has the disadvantage that the space of the hydrostatic piston engine increases considerably. In this case, a different arrangement can not be provided because due to the special nature of the impeller blade ends must be located directly in the area of entry into the control animals.

The invention has for its object to provide a hydrostatic piston engine, in which the speed limit existing by the suction-side flow conditions is increased.

The object is achieved by the piston engine according to claim 1.

In the hydrostatic piston engine according to the invention, a cylinder drum is rotatably mounted in a housing. In the cylinder drum a plurality of cylinder bores are arranged, which are connectable via cylinder openings in the cylinder drum with a first and a second control opening. During one revolution of the cylinder drum, the cylinder openings of the cylinder bores are alternately connected to the first and second control ports. The first control port communicates with a low pressure line and the second control port communicates with a high pressure line. For generating a volume flow in the circumferential direction, a first port of a channel and opposite a second port of the channel are connected to the first control port. The opposite arrangement of the two ports of the channel results in a secondary circuit, wherein the first control opening is provided as part of this auxiliary circuit. This creates a flow through the channel, wherein the fluid flowing through the channel undergoes an acceleration to each of the pressure medium sucked from the low-pressure line and supplied to the cylinder bores via the first control opening. By this acceleration, the sucked and sucked into the cylinder bores pressure fluid undergoes a tangential component.

It is particularly advantageous that only one additional channel is to be provided for generating the tangential velocity component. An auxiliary pump can be completely dispensed with in the simplest case. The formation of the flow is not caused by the acceleration by means of the wings of an impeller, but solely due to the flow in the secondary circuit during the suction of the pressure medium from the low-pressure line. A part of the pressurized fluid sucked in from the low-pressure line through the control port is used to fill the cylinder bore, whereas the other part flows into the port connected to the control port at the first port. About the channel, the pressure medium is conveyed back to the second port, where it meets the inflowing from the low pressure line pressure fluid and thus provides an acceleration of the sucked pressure fluid in the circumferential direction.

In the dependent claims advantageous developments of the hydrostatic piston engine according to the invention are carried out.

In particular, it is advantageous to arrange the first and the second connection on a common circumferential circle, which is arranged centrally about the axis of rotation of the cylinder drum. In this way, the flow direction formed in the first control opening coincides exactly with the circumferential direction of the cylinder drum. The flow direction in the first control opening and the direction of movement of the cylinder opening are thus parallel along the first control opening, which improves the entry conditions for the pressure medium into the cylinder bores. Thus it comes not to the dreaded cavitation and the maximum speed can be increased. For this purpose, it is particularly advantageous to arrange the portions of the channel adjoining the first control opening tangentially with respect to the circumferential circle. Due to the tangential arrangement of the sections in the area around the first control opening, a vortex formation in the flow is prevented and thus likewise the risk of the occurrence of cavitation is reduced.

In order to achieve a particularly favorable acceleration of the sucked pressure medium from the low pressure line, it is advantageous if the low pressure line discharges into the channel. The pressure medium conveyed in the channel in a circle as well as the newly sucked-in pressure medium from the low-pressure lines are thus already mixed with one another before entering the area of the first control opening and brought to a common speed. The pressure medium is then supplied via the common port of the first control port, whereby no mutual negative influence on the flow direction can occur through two existing in the region of the first control port connections.

Furthermore, it is advantageous to provide a connecting portion of the channel on the outside of a connecting plate of a hydrostatic piston machine. By such an external arrangement, the casting geometries required to make the terminal plate are kept simple. It is only necessary to provide the connections to the first control opening on the connection plate. By means of proven connection and sealing techniques, a piping can then be arranged on the outside of the connection plate in a simple manner. On the other hand, it is advantageous to form the channel completely within the terminal plate. With a channel arrangement provided within the connection plate, it is achieved that no additional pipelines are required on the outside of the hydrostatic piston machine. On the one hand, this frees the outer surfaces of the connection plate, so that connection possibilities of the pressure or high-pressure line can be easily realized and, on the other hand, the channel is thus protected against mechanical damage.

In this case, a particularly advantageous arrangement of the channel is arranged in a formed between the two control openings portion of the connection plate. The provision of the channel in the region between the two control openings leads to an optimized utilization of the existing installation space of the connection plate. An enlargement of the connection plate, wherein the channel is accommodated in the enlarged area, is therefore not necessary. In addition, the control opening is generally kidney-shaped, so that the flow takes place at an arranged between the control kidney channel approximately along an oval. Stronger deflections, such as those required for out-of-control channel passage, can thus be dispensed with.

In addition, it may be advantageous to connect the channel to an auxiliary pump. Thus, even higher flow velocities can be achieved within the channel and thus the peripheral speed of the pressure medium in the region of the first control opening can be adapted to even higher rotational speeds.

Fig. 1

eine Schnittdarstellung einer hydrostatischen Kolbenmaschine;

Fig. 2

eine schematische Darstellung eines ersten Ausführungsbeispiels einer Anschlussplatte der erfindungsgemäßen hydrostatischen Kolbenmaschine;

Fig. 3

eine schematische Darstellung eines zweiten Ausführungsbeispiels einer Anschlussplatte einer erfindungsgemäßen hydrostatischen Kolbenmaschine und

Fig. 4

eine Ansicht der Anschlussplatte entlang des Schnittes III-III der Fig. 3.

Embodiments of the hydrostatic piston engine according to the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1

a sectional view of a hydrostatic piston engine;

Fig. 2

a schematic representation of a first embodiment of a connection plate of the hydrostatic piston machine according to the invention;

Fig. 3

a schematic representation of a second embodiment of a connection plate of a hydrostatic piston machine according to the invention and

Fig. 4

a view of the connection plate along the section III-III of Fig. 3 ,

Before discussing specific embodiments for the realization of a connection plate of a hydrostatic piston machine according to the invention, a hydrostatic piston engine 1 with its essential components will first be explained for a better understanding. The hydrostatic piston machine 1 has a connection plate 2, which forms a housing of the hydrostatic piston machine 1 together with a housing part 9. Inside the housing, a drive shaft 5 is rotatably mounted in a first bearing 17 and a second bearing 18, wherein a portion 24 of the drive shaft 5 is rotatably connected to a corresponding portion 23 of a cylinder drum 6. The cylinder drum 6 is located on the terminal plate 2 facing the end of a control mirror 4, which is designed spherical in the illustrated embodiment and the cylinder drum 6 centered in this way on a corresponding recess.

For connecting a high-pressure or a low-pressure line, a first control opening 12 and a second control opening 15 are provided in the connection plate 2. The control openings 12 and 15 are over Low pressure or high pressure ports 16S and 16D connected to a low pressure line or a high pressure line, which in the Fig. 1 are not shown. In the illustrated embodiment, the control mirror 4 with the first control port 12 and the second control port 15 corresponding openings 19 and 20, respectively.

In the cylinder drum 6 a plurality of cylinder bores 26 are arranged. On the side facing the connection plate 2, the cylinder drum 6 has a cylinder opening 27 for each bore. The cylinder openings 27 are arranged in the cylinder drum 6 so that they are alternately connected to the opening 19 or 20 and thus to the first control opening 12 and the second control opening 15 during rotation of the cylinder drum 6.

In the cylinder bores 26 bushings 28 are introduced. In the liners 28 each piston 29 are arranged. The pistons 29 are connected via a ball joint 30 with a sliding shoe 31. The shoe 31 is supported on a disc 32. For hydrostatic relief of the sliding blocks 31 and for lubricating the contact surface between the sliding block 31 and the disc 32, a lubricating oil bore 33 is provided in the sliding block 31. The lubricating oil bore 33 is in contact with the cylinder bore 26 via a bore 34 arranged in the piston 29 and is thus supplied with lubricant during a pressure stroke.

The disc 32 is fixedly connected to a pivoting cradle 3, on which a lever arm 14 is arranged. The lever arm 14 is in operative connection with an adjusting piston 13, whereby the inclination angle of the pivoting cradle 3 relative to the axis of rotation of the drive shaft 5 is adjustable. Due to the inclination of the pivoting cradle 3, the pistons 29 in the cylinder drum 6 in their respective cylinder bores 26 perform a lifting movement. During one Suction is sucked via the low pressure port 16S and the first control port 12 pressure fluid into the cylinder bore 26. Accordingly, during a pressure stroke, the pressure medium displaced from the cylinder bore 26 by the piston 29 is conveyed via the second control opening 15 and the high-pressure port 16D, for example, into a working line (not shown).

In the Fig. 2 is a schematic representation of a first embodiment of a connection plate 2 of a hydrostatic piston machine 1 according to the invention shown. The connection plate 2 is in the Fig. 2 shown with its interior of the hydrostatic piston engine 1 facing side. In the connection plate 2, a first control opening 12 and a second control opening 15 can be seen. The first control port 12 and the second control port 15 are formed as a control. The control kidneys extend along a circumferential circle 35 which is arranged centrally with respect to the axis of rotation of the drive shaft 5. The radius of the circumferential circle 35 corresponds to the distance of the center of the cylinder openings 27 from the axis of rotation of the drive shaft 5. Thus, during one revolution of the cylinder drum 6, the cylinder openings 27 are alternately in registration with the first control opening 12 and the second control opening 15th

In the illustrated embodiment, the second control port 15 is connected via the high pressure port 16D to a high pressure side working line of a hydraulic circuit, not shown. On the other hand, the first control opening 12 communicates with a tank volume 36 via the low-pressure connection 16S. The illustrated connection plate is provided for connection of the hydrostatic piston machine 1 in an open circuit.

During operation of the hydrostatic piston machine 1 as a pump, pressure medium is sucked out of the tank volume 36 via the low-pressure connection 16S and conveyed into the cylinder chambers 26 via the first control opening 12 and the respectively associated cylinder openings 27 during a suction stroke. According to the invention, a channel 37 is provided which forms a secondary circuit and is connected to the first control port 12 via a first connection 38 and a second connection 39. Adjacent to the first connection 38 or second connection 39, the channel 37 has a first section 40 and a second section 41, respectively. The first section 40, which adjoins the first connection 38, runs initially along the circumference circle 35 or tangentially, before it is guided to a pipe connection 42 towards the outside of the connection plate 2.

Accordingly, adjacent to the second connection 39, the second section 41 of the channel 37 also continues along the circumference circle 35 or tangentially, before it is led out of the connection plate 2 toward a second pipe connection 43. According to the first exemplary embodiment, the first pipe connection 42 is connected to the second pipe connection 43 via an external piping 44. For simplicity, the outer casing is shown in one piece. However, it is equally possible to provide a multi-part casing 44, wherein it may be particularly advantageous to increase the flow velocity within the channel 37 through an auxiliary pump arranged in or connected to the channel 37.

In the illustrated embodiment, the merging of the low pressure port 16 S and the channel 37 is provided outside of the terminal plate 2. The channel 37 has for this purpose a branch 45. The common entry of the pressure medium sucked in via the low-pressure connection 16S with the pressure medium flowing in the channel 37 through the first pipe connection 42 and the common first portion 40 has the advantage that at the time of entry into the first control port 12, the entire flowing pressure medium already has a substantially homogeneous velocity distribution. This affects both the amount of speed and the direction of flow. The direction of flow is approximately parallel to the plane of the drawing and runs along the circumferential circle 35 in the direction indicated by the arrow. The direction of flow thus coincides with the direction of rotation of the cylinder drum 6, wherein a match of the rotational speed with the flow velocity along the circumference circle 35 of the first control opening 12 is preferably provided.

Instead of the branch 45 outside the connection plate 2, it is also possible to provide a low-pressure connection 16S for supplying the pressure medium from the tank volume 36, which is connected via a separate connection point with a corresponding channel within the connection plate 2. The channel 37 is to be executed in each case as low loss.

In the Fig. 3 is a further embodiment of a connection plate. 2 'shown. In contrast to the previously explained embodiment, the channel 37 in the embodiment of the Fig. 3 designed as an internal channel within the connection plate 2 '. In this case, the channel 37 in the region of the sections 40 'and 41' adjacent to the first terminal 38 and the second terminal 39 is preferably also continued in the circumferential direction. The first section 40 'and the second section 41' are connected to one another via a connecting section 50 of the channel 37, this connecting section 50 being arranged between the first control opening 12 and the second control opening 15.

The merging of the pumped in the channel 37 in the circuit pressure medium and the low pressure port 16S sucked pressure medium takes place in a unification region 51, which is preferably arranged in the region of the first portion 40 '. By arranging the merging region 51 in the region of the first section 40 ', it is ensured that the two partial flows in the channel 37 and the low-pressure port 16S reach a uniform flow direction at the first port 38 before entering the first control port 12.

Both in the Fig. 2 as well as in the Fig. 3 is indicated by the dashed representation that the individual channel sections or connections in a non-visible region of the connection plate 2 and 2 'and to which in the Fig. 1 or 2 shown visible surface of the connection plates 2 and 2 'are not open.

A sectional view of the connection plate 2 'along the line III-III is in the Fig. 4 shown. On the right side of the Fig. 4 is the interior of the housing of the hydrostatic piston engine 1 facing side of the connection plate 2 'shown. Accordingly, the outlets of the first control opening 12 and the second control opening 15 can be seen. In the connection region 51 adjoining the first control opening 12, in the exemplary embodiment illustrated, a suction line channel 52 and the first section 40 'open out. The two partial flows combine in the merging region 51 and flow together into the region of the first control opening 12.

Claims (9)

1. A hydrostatic piston engine with a cylindrical drum (6) mounted in a rotatable manner within a housing (2, 9), in which several cylindrical boreholes (26) are arranged, which can be connected via several cylindrical openings (27) provided in the cylindrical drum (6) to a first control opening (12) and to a second control opening (15), wherein the first control opening (12) is connected to a low-pressure line, and the second control opening (15) is connected to a high-pressure line,
   wherein the first control opening (12) is formed as a kidney-shaped control port disposed on a peripheral circle (35) arranged around a rotational axis of the cylindrical drum (6),
   characterised in that
   a first connection (38) and a second connection (39), which are connected to one another via a channel (37), are formed at opposing ends of the first control opening (12) in the peripheral direction.
2. The hydrostatic piston engine according to claim 1,
   characterised in that
   the first connection (38) and the second connection (39) are disposed on a peripheral circle (35) arranged around a rotational axis of the cylindrical drum (6).
3. The hydrostatic piston engine according to claim 1 or 2,
   characterised in that
   portions (40, 41) of the channel (37) limiting the first and/or the second connection (38, 39) extend in a tangential manner relative to the peripheral circle (35) or extend in the peripheral direction.
4. The hydrostatic piston engine according to any one of claims 1 to 3,
   characterised in that
   the low-pressure line opens into the channel (37).
5. The hydrostatic piston engine according to any one of claims 1 to 4,
   characterised in that
   the piston engine (1) is a hydrostatic pump in the open circuit, and the-low pressure line is a vacuum line.
6. The hydrostatic piston engine according to any one of claims 1 to 5,
   characterised in that
   at least one connecting portion of the channel is formed as an externally disposed pipe (44) on a connecting plate (2).
7. The hydrostatic piston engine according to any one of claims 1 to 5,
   characterised in that
   the channel (37) is formed in the connecting plate (2').
8. The hydrostatic piston engine according to claim 7,
   characterised in that
   the channel is arranged in a portion of the connecting plate (2') formed between the first control opening (12) and the second control opening (15).
9. The hydrostatic piston engine according to any one of claims 1 to 8,
   characterised in that
   the channel (37) is connected to an auxiliary pump.

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