EP3572669B1 - Connection assembly with feed pump and elastic element - Google Patents

Description

The invention relates to a connection assembly according to the preamble of claim 1.

From the DE 10 2007 011 644 B4 an axial piston machine with a connection assembly is known which comprises a feed pump. The connection assembly is designed in such a way that only a few parts have to be changed in order to adapt the connection assembly to feed pumps with different delivery rates.

From the DE 41 02 162 A1 In addition, an internal gear pump is known in which the pinion is pressed against an end face of a base plate by means of an elastic element in the form of a plate spring.

One advantage of the present invention is that even fewer parts have to be changed in order to adapt the connection assembly to feed pumps with different delivery rates. In particular, no changes need to be made to the cover or intermediate rings provided there can be omitted. In addition, the connection assembly in the area of the feed pump is completely tight even if parts with unfavorable dimensions are combined with one another within the manufacturing tolerance.

According to the independent claim, it is proposed that an elastic element is installed under prestress between the cover and the receiving part in such a way that a corresponding prestressing force is supported at least indirectly on the base body via the sealing surface. The named parts of the pump assembly preferably jointly define the sealing plane. The pretensioning force mentioned is preferably static on the base body in the area of the receiving part and / or the outer part supported. In the area of the inner part, the pretensioning force is preferably supported by the hydrostatic forces occurring on the base body during operation, with essentially no force being supported by the inner part when the machine is at a standstill. The force acting on the pump assembly via the sealing surface in the direction of the axis of rotation is preferably supported exclusively via the elastic element. The receiving part and the cover are preferably arranged at a distance from one another everywhere. The outer part and the inner part are preferably in sealing contact with the base of the first recess or with a wear plate arranged there. The first and / or the second recess are preferably each circular-cylindrical and arranged parallel to the axis of rotation. The first and the second recess are preferably arranged eccentrically to one another.

In the dependent claims, advantageous developments and improvements of the invention are specified.

It can be provided that the elastic element is designed as a separate component. In contrast, the receiving part and / or the cover are essentially rigid, and they are preferably made of metal, in particular steel, cast iron or aluminum. The pretensioning force of the elastic element can thus be adjusted in a simple manner so that no leaks occur in the area of the sealing surface. In particular, high pretensioning forces can also be achieved, so that the elastic element can also absorb high hydraulic forces. The elastic element is preferably made of steel, most preferably of hardened spring steel.

It can be provided that the elastic element is formed in one piece. It is therefore particularly easy to manufacture. It is preferably intended to bend the elastic element from a wire or to punch it out of a sheet metal.

It can be provided that the elastic element surrounds the axis of rotation in a ring-like manner. It is preferably designed as a circular ring. Its outer ring diameter is preferably between 80% and 95% of the outer diameter of the receiving part. The Dimensions of the elastic element are thus made as large as possible. The elasticity of the elastic element can thus be easily adjusted, while at the same time it can transmit high forces.

It can be provided that the elastic element is designed in the manner of a wave spring. The elastic element preferably has a constant, for example rectangular, cross-sectional shape over its circumference. It runs along its circumference, preferably curved like a wave.

It can be provided that the elastic element is designed to be interrupted in the circumferential direction. Accordingly, it has the shape of a slotted ring. This results in a defined rigidity of the elastic element, which is defined solely by the flexural rigidity of the individual wave-shaped sections, which can easily be determined by calculation.

It can be provided that the elastic element is received in a groove in the receiving part that runs around the axis of rotation in an annular manner. In this way, the position of the elastic element is positively fixed transversely to the axis of rotation. The pretensioning force acts centrally on the receiving part, so that there is no need to fear that it will become wedged in the second recess or that its mobility is inhibited in some other way.

It can be provided that the depth of the groove, measured in the direction of the axis of rotation, is less than the corresponding height of the unstressed elastic element. The depth mentioned is preferably also less than the corresponding height of the elastic element in the fully assembled state. This ensures that the cover rests exclusively on the elastic element, but not on the receiving part.

It can be provided that the pump assembly rests on the base body via a separate wear plate, the wear plate having at least two openings, each between the inner part and the Open out into the outer part, the wear plate being non-rotatably connected to the base body, at least one opening being fluidically connected to an associated fluid connection. The wear plate is preferably designed as a flat plate with a constant thickness. The openings are preferably kidney-shaped. The wear plate is preferably made of brass or of coated steel, in particular of manganese-phosphated steel.

It can be provided that an outer circumferential surface of the wear plate and an outer circumferential surface of the receiving part are designed to be aligned with one another in the direction of the axis of rotation. The named outer circumferential surfaces are preferably circular-cylindrical with respect to the axis of rotation.

It can be provided that at least one opening is assigned a third recess which is arranged at the base of the first recess. This results in additional pressure equalization between the individual pressure chambers of the feed pump. The openings in the wear plate already cause a comparable pressure compensation. The peripheral shape of the third recesses, preferably viewed in the direction of the axis of rotation, is congruent with the peripheral shape of the respectively assigned opening in the wear plate.

Protection is also claimed for a collection which comprises at least two connection assemblies according to the invention, the base body, the cover and the drive shaft of all connection assemblies being identical, the outer parts and the inner parts of the various connection assemblies differing, with an outer shape of the receiving part in all connection assemblies is designed identically, with an inner shape of the receiving part being designed differently in the various connection assemblies. The outer parts and the inner parts of the various connection assemblies preferably differ with regard to the width measured in the direction of the axis of rotation.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.

Fig. 1

einen Längsschnitt einer erfindungsgemäßen Anschlussbaugruppe;

Fig. 2

eine perspektivische Ansicht des Innenteils, des Außenteils und der Antriebswelle;

Fig. 3

eine weitere perspektivische Ansicht der Baugruppe nach Fig. 2;

Fig. 4

eine perspektivische Ansicht des Aufnahmeteils;

Fig. 5

eine weitere perspektivische Ansicht des Aufnahmeteils; und

Fig. 6

eine perspektivische Ansicht des elastischen Elements.

The invention is explained in more detail below with reference to the accompanying drawings. It shows:

Fig. 1

a longitudinal section of a connection assembly according to the invention;

Fig. 2

a perspective view of the inner part, the outer part and the drive shaft;

Fig. 3

a further perspective view of the assembly according to Fig. 2 ;

Fig. 4

a perspective view of the receiving part;

Fig. 5

a further perspective view of the receiving part; and

Fig. 6

a perspective view of the elastic element.

Fig. 1 shows a longitudinal section of a connection assembly 10 according to the invention. The connection assembly 10 is for use in the axial piston pump according to the German patent application with the file number 102017213457.7 intended. The entire content of this patent application is incorporated by reference into the content of the present application. The connection assembly 10 is referred to in the cited patent application as a housing cover, the term connection plate also being common.

The connection assembly 10 comprises a base body 20, which is produced, for example, using a casting process. The base body 20 forms at least one fluid connection 21, wherein in Fig. 1 only the suction connection is visible during the Pressure connection is not visible. In the direction of an axis of rotation 11, the base body 20 is penetrated by a drive shaft 30, which in the present case has a first and a second shaft part 31; 32 which are connected to one another in a rotationally fixed manner with respect to the axis of rotation 11, for example by means of a spline, a feather key drive or a hexagonal connection. The first shaft part 31 carries the cylinder drum of the axial piston machine, the second shaft part 32 carrying the feed pump 40. The feed pump 40 is in the present case designed as an internal gear pump, it also being possible for it to be designed as a vane pump. In both cases it comprises an inner part 41, which is connected to the drive shaft 30 in a rotationally fixed manner. The inner part 41 is surrounded in a ring-like manner by an outer part 42. There are several pressure spaces between the inner and outer parts, the volume of which changes when the drive shaft 30 rotates. In the case of an internal gear pump, these pressure chambers are created by toothing on the inner and outer parts 41; 42 fluid-tight delimited from one another. In the case of a vane pump, they are separated from one another in a fluid-tight manner by radially movable vanes.

The connection assembly 10 according to the invention has the advantage that it can be flexibly adapted to different feed pumps, which differ in particular with regard to the width of the inner and outer parts 41; 42 differ in the direction of the axis of rotation 11. The base body 20, the drive shaft 30 and the cover 80 can be designed identically in all construction variants. There are only differences in the inner and outer part 41; 42 to achieve the desired delivery rate. The inner shape of the receiving part 50 is designed to be correspondingly adapted, the outer shape of the receiving part 50 being identical in all construction variants.

The inner part 41, the outer part 42 and the receiving part 50 together form a pump assembly 12, all of the named parts having a common flat sealing surface 13. The receiving part 50 is received in a second recess 22 of the base body, which is preferably designed as a circular cylinder with respect to the axis of rotation 11. The receiving part 50 is secured against rotation about the axis of rotation 11 by means of a cylindrical pin 55. The sealing surface 13 is present via a separate wear plate 70 on the flat base of the second recess 22, and it can also lie directly there. The wear plate 70 is designed in the form of a flat plate of constant thickness, which consists for example of brass. It is also secured against twisting with the cylinder pin 55 (see Fig. 2 ).

The outer part 42 is received in a first recess 51 in the receiving part 50. The first recess 51 has a circular cylindrical design, being arranged eccentrically to the axis of rotation 11. In the case of the present internal gear pump, the outer part 42 is rotatably received there. In the case of a vane pump, the outer part, namely the stroke ring, is received there in a rotationally fixed manner.

The receiving part 50 is covered at least in sections by a cover 80, the cover 80 being screwed to the base body 20. The cover 80, as shown here, can have an opening so that a drive through to a directly attached hydraulic machine is possible. But it can also be a closed cover. A sealing ring 81 is installed between the cover 80 and the base body 20 in order to prevent fluid from escaping. The elastic element 60 according to the invention is installed under prestress between the cover 80 and the receiving part 50. The corresponding pretensioning force acts in the direction of the axis of rotation 11, being supported on the cover 80 and on the sealing surface 13 via the touch contact. The receiving part 50 has some freedom of movement in the second recess 22 in the direction of the axis of rotation 11, so that the entire pump assembly 12 with its sealing surface 13 is pressed against the wear plate 70 and this in turn is pressed against the bottom of the second recess 22. There is accordingly a fluid-tight seal.

The cover 80 is aligned transversely to the axis of rotation 11 via a circular cylindrical centering extension 56. In the direction of the axis of rotation 11, it rests on a flat surface of the base body 20. The cover is in the area of the receiving part 50 80 carried out at a distance from the receiving part 50, so that the mentioned freedom of movement is available.

Fig. 2 shows a perspective view of the inner part 41, the outer part 42 and the drive shaft 30. The outer toothing 43 on the inner part 41 and the inner toothing 44 on the outer part 42, which mesh with one another, can be seen. Opposite to the meshing of the teeth, at least one pair of teeth are in fluid-tight contact with one another, so that at least two pressure chambers which are delimited from one another in a fluid-tight manner and whose volume changes when the second shaft part 32 rotates. The second shaft part 32 is secured by means of two sliding rings 33 (see also Fig. 3 ) on the main body and on the receiving part (No. 22; 40 in Fig. 1 ) rotatably supported with respect to the axis of rotation. It can also be seen how the cylinder pin 55 engages in a recess on the outer circumference of the wear plate 70 in order to secure it against rotation. The outer circumferential surface 72 of the wear plate 70 is circular-cylindrical with respect to the axis of rotation. With the separate holding plugs 73, the wear plate 70 is aligned transversely to the axis of rotation. The holding plugs 73 engage in each of the associated bores in the wear plate 70 and in the receiving part 50. The pump assembly preferably also includes the wear plate 70, and it can be installed as a whole in the base body.

Fig. 3 shows a further perspective view of the assembly according to FIG Fig. 2 . It can be seen that the holding plugs 73 protrude beyond the wear plate 70, whereby they are located at the bottom of the second recess (No. 22 in Fig. 1 ) issue. The two kidney-shaped openings 71 in the wear plate 70 can also be seen, which in the area of the toothing engagement between the inner and outer parts 41; 42 are arranged. A breakthrough 72 is connected to an associated fluid port (No. 21 in Fig. 1 ), the other opening being connected to the cylinder drum of the axial piston machine on the suction side.

Fig. 4 shows a perspective view of the receiving part 50 from the side facing the base body. The outer circumferential surface 54 and the opening 59 for the drive shaft are each circular cylindrical with respect to the axis of rotation 11. The first recess 51 is also designed as a circular cylinder, being arranged eccentrically and parallel to the axis of rotation 11. The end face of the receiving part 50 is flat and perpendicular to the axis of rotation 11, two bores 57 for the cylinder pin and two bores 58 for the holding plugs being arranged there.

Reference should also be made to the kidney-shaped third recesses 53, which are each arranged in the direction of the axis of rotation 11 in alignment with an associated opening on the wear plate. The third recesses 53 have a flat bottom surface which is oriented perpendicular to the axis of rotation 11. Its depth is accordingly constant.

Fig. 5 shows a further perspective view of the receiving part 50, from the side facing the cover. The centering extension 56 for the cover is circular-cylindrical with respect to the axis of rotation 11. A groove 52 for receiving the elastic element is also provided in the surface of the receiving part 50 which is covered by the cover. The groove 52 runs in a circular ring around the axis of rotation 11, with a constant depth in the direction of the axis of rotation 11. The groove is arranged as close as possible to the outer circumferential surface 54, so that the elastic element can be made particularly large.

Fig. 6 shows a perspective view of the elastic element 60. The elastic element 60 is designed as a separate component in the manner of a corrugated spring. It extends in a circular ring around the axis of rotation 11. It has an interruption 62 in the circumferential direction, so that it is a slotted ring. This has a lower spring stiffness than a closed ring. The elastic element 60 is preferably made of hardened spring steel. It has a constant, rectangular cross-sectional shape along its circumference, the shorter side of the rectangle being arranged parallel to the axis of rotation 11. The elastic element 60 runs in a wave-like manner in the circumferential direction, so that it is at the bottom of the groove (No. 52 in Fig. 5 ) and on the lid (No. 80 in Fig. 1 ) is only applied to several small-area contact areas 64. Present Four contact areas 64 are provided on each side, each of which is arranged on a wave trough or on a wave crest. The stiffness of the elastic element is higher the shorter the wavelength or the more contact areas 64 are provided. A contact area 64 is divided into two parts by the interruption 62, so that there both ring ends rest on the assigned part. The height 63 of the elastic element 60 in the direction of the axis of rotation 11, reduced by the thickness of the cross-sectional shape in the direction of the axis of rotation 11, corresponds to the maximum possible spring deflection of the elastic element 60. The preload of the elastic element is selected to be so great that the values that occur during operation hydrostatic forces are safely exceeded. As a result, on the sealing surface (No. 13 in Fig. 1 ) no leaks.

In Fig. 6 a shaft section 61 is also drawn in, which is defined by two immediately adjacent contact points 64 on one side of the elastic element 60. The rigidity of a shaft section 61 can be calculated approximately analogously to the rigidity of a centrally loaded, straight bending beam, the length of which is equal to the circumferential length of the shaft section 61. A more precise determination of the elasticity of the elastic element 60 is of course possible by means of the FEM calculation.

Reference number

10

Connection assembly

11

Axis of rotation

12

Pump assembly

13

Sealing surface

20th

Base body

21st

Fluid connection

22nd

second recess

30th

drive shaft

31

first shaft part

32

second shaft part

33

Slip ring

40

Feed pump

41

inner part

42

Outer part

43

External teeth of the inner part

44

Internal toothing of the outer part

50

Receiving part

51

first recess

52

Groove (for elastic element)

53

third recess

54

Outer peripheral surface of the receiving part

55

Straight pin

56

Centering process

57

Hole for cylinder pin

58

Hole for holding plug

59

Breakthrough for drive shaft

60

elastic element

61

Shaft section

62

Interruption

63

Height of the elastic element

64

Contact area

70

Wear plate

71

breakthrough

72

Outer peripheral surface of the wear plate

73

Retaining plug

80

cover

81

Sealing ring

Claims (12)

1. Connection assembly (10) for use in an axial piston machine, wherein the connection assembly (10) has a feed pump (40) and a main body (20), wherein the main body (20) is equipped with at least one fluid connection (21), wherein, in the main body (20), a drive shaft (30) is received so as to be rotatable with respect to an axis of rotation (11), wherein the feed pump (40) is designed as an internal gear pump or as a vane-type pump, wherein said feed pump has an inner part (41) and an outer part (42), wherein the inner part (41) is connected rotationally conjointly to the drive shaft (30), wherein the outer part (42) annularly surrounds the inner part (41), wherein a separate receiving part (50) with a first recess (51) is provided, wherein the outer part (42) and the inner part (41) are received in the first recess (51) such that a pump assembly (12) comprising the inner part (41), the outer part (42) and the receiving part (50) defines a planar sealing surface which bears at least indirectly against the main body (20), wherein the main body (20) has a second recess (22) in which the pump assembly (12) is received at least in certain portions, wherein a separate cover (80) is provided which covers the second recess (22) and the pump assembly (12) in each case at least in certain portions, wherein said cover bears against the main body (20),
   characterized in that an elastic element (60) is installed under preload between the cover (80) and the receiving part (50) such that a corresponding preload force is supported at least indirectly on the main body (20) via the sealing surface (13), wherein the stated preload force is, in the region of the receiving part (50) and/or of the outer part (42), supported on the main body (20) in static fashion.
2. Connection assembly according to Claim 1,
   wherein the elastic element (60) is formed as a separate component.
3. Connection assembly according to Claim 2,
   wherein the elastic element (60) is formed as a single piece.
4. Connection assembly according to any of the preceding claims,
   wherein the elastic element (60) annularly surrounds the axis of rotation (11).
5. Connection assembly according to Claim 4,
   wherein the elastic element (60) is formed in the manner of an ondular washer.
6. Connection assembly according to Claim 4 or 5,
   wherein the elastic element (60) is formed so as to be discontinuous in a circumferential direction.
7. Connection assembly according to any of Claims 4 to 6,
   wherein the elastic element (60) is received in a groove (52), which runs in encircling fashion annularly around the axis of rotation (11), in the receiving part (50).
8. Connection assembly according to Claim 7,
   wherein the depth of the groove (52) measured in the direction of the axis of rotation (11) is smaller than the corresponding height (63) of the unbraced elastic element (60).
9. Connection assembly according to any of the preceding claims,
   wherein the pump assembly (12) bears via a separate closure plate (70) against the main body (20), wherein the closure plate (70) has at least two apertures (71) which open out in each case between the inner part (41) and the outer part (42), wherein the closure plate (70) is connected rotationally conjointly to the main body (20), wherein at least one aperture (71) is fluidically connected to an associated fluid connection (21).
10. Connection assembly according to Claim 9,
    wherein an outer circumferential surface (72) of the closure plate (70) and an outer circumferential surface (54) of the receiving part (50) are formed in alignment with one another in the direction of the axis of rotation (11).
11. Connection assembly according to Claim 9 or 10,
    wherein at least one aperture (71) is assigned a third recess (53) which is arranged on the base of the first recess (51).
12. Collection comprising at least two connection assemblies (10), which are each designed as claimed in any of the preceding claims, wherein the main bodies (20), the covers (80) and the drive shaft (30) of all connection assemblies (10) are of identical form, wherein the outer parts (42) and the inner parts (41) of the various connection assemblies (10) differ, wherein an external shape of the receiving part (50) is of identical form in all connection assemblies (20), wherein an internal shape of the receiving part (50) is of different form in the various connection assemblies.

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