EP2672119A1 - Geared machine with hydrodynamic and hydrostatic bearing pins - Google Patents

Abstract

The machine (10) has two gear wheels (11) externally engaged with one another and surrounded by a housing (30). The gear wheels comprise a bearing pivot (13), which is rotatably accommodated in an assigned bearing bore (51) of the housing with respect to a rotational axis (14). The bore or pivot is provided with a groove, which is covered by a counterpart, the pivot or bore. The groove is endlessly rotatingly formed around the pivot. A recess i.e. oblong hole, is formed in the bore beside the groove and connected with a closed feed channel for supplying pressure fluid i.e. hydraulic oil.

Description

The invention relates to a gear machine according to the preamble of claim 1 or claim 11.

From the DE 1 006 722 a gear machine in the form of a pump is known. The gear machine includes two gears that mesh with each other in external engagement. The tooth edges are surrounded by a housing, which consists of a main body and two bearing bodies. The gears lie with their tip diameter sealingly against the main body and with its two side surfaces sealingly against the associated bearing body. A rotation of the gears is thus accompanied by a fluid flow between a first and a second fluid port in the housing. Both toothed edges are provided on both sides with a circular cylindrical bearing journal. The bearing journal is rotatably received in an associated bearing bore with respect to a rotational axis, wherein the bearing bore in the bearing bodies, ie in the housing, is arranged.

The bearing bore is provided with a groove which is covered by the journal. The groove is connected to a feed channel, via which it can be filled with pressurized pressurized fluid, in particular hydraulic oil. On the surface, which is bounded by the endless groove, so called on the pressure. The position of said surface is chosen so that the resulting force from the pressure forces acting there counteracts the force which exerts the pressure fluid on the teeth of the gear.

The disadvantage of the known gear machine is that it is designed for operation at a certain speed of the gears. If a deviation from this design speed occurs during operation, then excessive wear occurs Bearing or the bearing bore, so that the life of the gear machine decreases.

The object of the invention is to provide a gear machine that can be operated at different speeds of the gears, without excessive wear on the bearing pin or the bearing bore occurs.

According to the independent claim 1, this object is achieved in that the groove is formed endlessly circumferentially around the bearing pin around, wherein on one side next to the groove in the bearing bore at least a first recess is provided, which is connected to a closed feed channel for supplying pressurized fluid. The groove is preferably not connected to pressurized fluid under pressure. It is rather thought that the pressurized fluid, which flows from the bearing gap between the bearing pin and the bearing bore into the groove, is discharged from the groove substantially without pressure. This is preferably done by the pressure fluid from the groove flows back into the bearing gap and indeed in a zone in which a low pressure prevails. This is facilitated by the fact that the groove runs endlessly around the bearing journal. If this is not sufficient to remove the pressure fluid from the groove, the groove may be additionally connected to a separate discharge channel for discharging pressurized fluid. This discharge channel leads, for example, to the low-pressure connection of the housing or to a pressure chamber in the housing in which the pressure fluid has a low pressure.

As a result, the groove divides the journal into two areas. In the first region, in which the first recess is not arranged, a hydrodynamic lubricant film forms between the bearing journal and the bearing bore, which completely separates the bearing journal from the bearing bore, so that they do not touch each other directly. This happens especially when the gears rotate at a high speed. In the second region in which the first recess is arranged, pressure fluid under pressure is introduced into the bearing gap via the supply channel and the first recess. This can form a lubricating film at a very low speed of the gears, the journal completely separated from the bearing bore. Consequently, at both low and high speeds of the gears, there is a bearing lubricating film between the journal and the associated bearing bore so that excessive wear does not occur.

The feed channel is preferably connected directly to the first recess. It is designed to be closed, so that the pressure fluid, which is located in the feed channel, does not interfere with the formation of the lubricating film. The lubricating film is thus influenced primarily by the position and the shape of the first recess. In this case, preferably, a single first recess is provided so that the gear machine can be made particularly simple.

In the dependent claims advantageous refinements and improvements of the invention are given.

The bearing bore may be arranged in a separate bearing body, which bears against a side surface of the associated gear, wherein the feed channel is arranged exclusively in the bearing body. The bearing body is a comparatively small component, so that the supply channel can be made there particularly easily.

The feed channel may lead into the area of teeth of the gear, so that there is a fluid exchange connection between the interdental spaces and the feed channel. This can flow under pressure from the interdental spaces in the feed channel and thus over the first recess in the bearing gap between the bearing pin and bearing bore under pressure. The position of the mouth opening of the feed channel on the circumference of the associated gear, the pressure of the pressurized fluid can be controlled in the feed, so that there is an optimal lubricating film.

The mouth opening of the feed channel may be wider on the associated gear in the circumferential direction with respect to the axis of rotation than a tooth of the gear. This ensures that said mouth opening can not be completely covered by a tooth of the gear. As a result, in each rotational position of the gear a fluid exchange connection between at least one tooth space and the feed channel. The pressure in the feed channel is accordingly constant. A pressure pulsation which disturbs the lubricating film does not occur.

The housing may have a pressure port, wherein the feed channel is connected to the pressure port. The pressure port may be the high-pressure port of the housing to which the pressurized fluid flowing through the gear machine is supplied at high pressure. But it can also be provided a separate pressure port, is supplied to the pressurized fluid with a specially set pressure from a separate fluid source.

The groove may extend in a plane which is oriented perpendicular to the axis of rotation of the associated journal, preferably having a constant cross-sectional shape. Thus, the groove extends in the direction of the associated axis of rotation over the smallest possible length. In this area, no bearing lubricating film can form. Thus, the lowest possible bearing width is lost at the journal by the proposed groove. A groove with a constant cross-sectional shape can be produced particularly easily, for example on a lathe.

The bearing bore can be formed by a separate bearing bush, wherein the first recess is formed by a radial opening in the bearing bush, wherein the feed channel is arranged in the remaining housing. The first recess can therefore be produced particularly easily, for example by means of a milling process. The milling can be made in particular from radially outward on the bearing bush, so that even very filigree shapes of the first recess are easy to produce. The feed channel in the remaining housing is preferably designed to be open at least in sections, wherein it is covered by the bearing bush, so that in the result is a closed feed channel. As a result, the production of the feed channel is simplified.

The breakthrough may be formed in the form of a slot which is aligned parallel to the axis of rotation of the associated journal. A slot can be made very easily with an end mill. The slot preferably extends over substantially the entire width between the groove and the edge of the bearing bush. This forms at low speeds over the entire area between the groove and the edge of the bearing bush a bearing lubricating film. This can support large forces due to its large area.

The bushing may be integrally formed, wherein the groove is limited exclusively by the bearing bush. Thus, the groove can be made by machining the comparatively small bushing alone. This is particularly simple and therefore inexpensive.

The bearing bush may have a first and a separate second socket part, which delimit the groove laterally. A special chip-removing machining for the production of the groove is therefore no longer necessary. The width of the groove can also be arbitrarily set during assembly of the gear machine. Further, the width of the bearing gap between the first sleeve part and the journal and the second sleeve part and the journal can be formed differently to improve the formation of the lubricating film.

According to the independent claim 11, the groove for the defined delimitation of the first and the second area can also be dispensed with. In this case, said first recess is arranged completely next to a plane which is arranged perpendicular to the associated axis of rotation in the middle of the contact region between the bearing bore and bearing journal. This embodiment is particularly simple, since it is dispensed with the provision of a special groove.

Fig. 1

einen Längsschnitt einer ersten Ausführungsform einer erfindungsgemäßen Zahnradmaschine, wobei die Schnittebene durch die Drehachsen der Zahnräder verläuft;

Fig. 2

einen Längsschnitt eines Lagerkörpers der Zahnradmaschine nach Fig. 1;

Fig. 3

einen Querschnitt des Lagerkörpers nach Fig. 2, wobei die Lage der Schnittebene in Fig. 2 mit A-A gekennzeichnet ist;

Fig. 4

einen Längsschnitt eines Lagerkörpers gemäß einer zweiten Ausführungsform der Erfindung; und

Fig. 5

einen Längsschnitt eines Lagerkörpers gemäß einer dritten Ausführungsform der Erfindung.

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

Fig. 1

a longitudinal section of a first embodiment of a gear machine according to the invention, wherein the cutting plane passes through the axes of rotation of the gears;

Fig. 2

a longitudinal section of a bearing body of the gear machine after Fig. 1 ;

Fig. 3

a cross section of the bearing body after Fig. 2 , where the position of the cutting plane in Fig. 2 marked with AA;

Fig. 4

a longitudinal section of a bearing body according to a second embodiment of the invention; and

Fig. 5

a longitudinal section of a bearing body according to a third embodiment of the invention.

Fig. 1 shows a longitudinal section of a first embodiment of a gear machine 10 according to the invention, wherein the cutting plane passes through the axes of rotation of the gears 11. The gear machine 10 comprises a housing 30, which consists of a main body 31, a first and a second cover 33; 34 and a total of four separate bearing bodies 40 is composed. In the main body 31, two externally toothed gears 11 are received, which mesh with each other, wherein they have parallel axes of rotation 14. The tubular main body 31 has on the inner peripheral surface a constant in the direction of the rotation axes 14 cross-sectional shape, which is adapted to the gears 11, so that they rest with their tip diameter sealingly against the main body 31. The planar and perpendicular to the axes of rotation 14 aligned side surfaces 12 of the gears 11 each abut against an associated bearing body 40, which is pressed by the pressurized fluid in the gear machine 10 against the associated gear 11, so that the bearing body 40 tightly against the associated gear 11 , In the main body 31 are two pressure ports 32, namely a high pressure and a low pressure port provided, which before or behind the cutting plane of Fig. 1 are arranged.

When the gear machine 10 is operated as a pump, the toothed edges 11 are set in rotary motion with the drive pin 15, whereby the pressure fluid, in particular hydraulic oil, flows from the low-pressure connection to the high-pressure connection. When the gear machine is operated as a motor, the pressure fluid flows from the high-pressure port to the low-pressure port, wherein the drive pin 15 is set in rotational motion.

Both gears 11 have on both sides each one with respect to the associated axis of rotation 14 circular cylindrical bearing pin 13, which is received in a bearing bore 51 in the associated bearing body 40. The bearing bore 51 is formed on a separate bearing bush 50, which is pressed into the remaining bearing body 40. The two bearing bodies 40 on one side of the toothed wheel rest against one another on a flat contact surface 44. The four bearing bodies 40 are each formed symmetrically to a plane perpendicular to the axes of rotation 14 and beyond mirror symmetry to the flat contact surface 44. On its outer peripheral surface they are sealingly adapted to the inner peripheral surface of the main body 31, wherein they are in the direction of the axes of rotation 14th are received in the main body 31 minimally movable.

Attention is still on the first and the second cover 33; 34, with which the main body 31 is sealed at both ends. The drive pin 15 protrudes through the first cover 33 out of the housing 30, wherein the passage point is sealed with a (not shown) radial shaft sealing ring against leakage of the pressurized fluid.

Fig. 2 shows a longitudinal section of a bearing body 40 of the gear machine 10 after Fig. 1 , The bearing bush 50 is received in a receiving bore 41 in the bearing body 40, which is formed circular cylindrical with respect to the axis of rotation 14 of the associated gear. The bushing 50 includes a first and a second Bushing 54, 55, which are each designed as a circular cylindrical tube with a constant wall thickness. The inner peripheral surfaces of the bushing parts 54; 55 form the bearing bore 51, wherein both inner peripheral surfaces have the same diameter. The two end faces of the first and the second sleeve part 54; 55 are each formed flat and perpendicular to the axis of rotation 14 of the associated gear. The first and second sleeve parts 54; 55 are spaced apart so that there is a groove 52 therebetween. The side walls of the groove 52 are defined by the associated end faces of the first and second sleeve parts 54; 55 formed. The bottom wall of the groove 52 is formed by the bearing body 40, namely the receiving bore 41.

In the in Fig. 2 To the right of the groove 52 arranged first region 20, a single first recess 53 is arranged, which is in the form of an opening in the bearing bush 50, namely the first female part 54, is formed. The first recess 53 is formed in the form of a slot which extends parallel to the axis of rotation 14 of the associated gear. However, the first recess 53 may also have other shapes, as far as it is suitable for forming a lubricating film between the bearing bore 51 and the associated bearing pin. In addition, a plurality of first recesses 53 may be provided.

The first recess is directly connected to a feed channel 42, which has a closed channel cross-sectional shape. Via the feed channel 42, pressurized fluid under pressure can be supplied to the first recess 53 so that it flows into the bearing gap between the bearing bore 51 and the bearing journal.

In the in Fig. 2 To the left of the groove 52 arranged second region 21 is provided no special inflow opening for the pressurized fluid. In the local bearing gap between the bearing bore 51 and the bearing pin is therefore exclusively pressurized fluid, which passes through unavoidable leaks there. The corresponding lubricating film therefore only has a sufficiently large thickness, the bearing pin to separate completely from the bearing bore when the gears rotate at a high speed of for example 3000 min ^-1.

The width of the first and second regions 20; 21 and thus the width of the first and the second sleeve part 54, 55 is selected so that the respective lubricating films have approximately the same capacity. In the first region 20, in which the pressure fluid is supplied under pressure, a smaller width is sufficient than in the second region 21 in order to achieve the same load-bearing capacity.

Fig. 3 shows a cross section of the bearing body 40 after Fig. 2 , where the position of the cutting plane in Fig. 2 marked with AA. The feed channel 42 is formed by a circular cylindrical bore, which intersects the receiving bore 41 in the bearing body 40. There, the feed channel 42 is covered by the bearing bush 50, namely the first socket part, so that the pressure fluid from the feed channel 42 can flow exclusively through the first recess 53 into the bearing gap. Due to the large diameter of the feed channel 42, this is associated with low pressure losses.

In the region of the mouth of the feed channel 42, a third recess 45 is provided on the radial outer surface of the bearing body 40, which extends over the entire width of the bearing body 40. Via the third recess 45, a fluid exchange connection between the high pressure port on the housing of the gear machine and the feed channel 42 is established. Accordingly, the pressure at which the pressurized fluid flows into the bearing gap is equal to the pressure at the high pressure port of the gear machine.

Fig. 4 shows a longitudinal section of a bearing body 40 according to a second embodiment of the invention. The second embodiment differs from the first embodiment exclusively in that instead of a first and a separate second socket part, a one-piece bearing bushing 50 is provided. The bushing 50 is formed in the form of a circular cylindrical tube with a constant wall thickness. The groove 52 is limited only by the bushing 50. It runs around the bearing pin in a plane that is vertical is formed to the axis of rotation 14 of the associated gear. The cross-sectional shape of the groove 52 is constant and may be formed, for example, rectangular, square or semicircular.

Incidentally, on the execution to the Fig. 1 to 3 with respect to the first embodiment, wherein like parts are identified by like reference numerals.

Fig. 5 shows a longitudinal section of a bearing body 40 according to a third embodiment of the invention. The third embodiment differs from the first and second embodiments exclusively in that the groove which delimits the first from the second region has been completely omitted. However, the fact that the first recess 53 is arranged eccentrically results in approximately the effect according to the invention as in the first and the second embodiment of the invention. An off-center arrangement should be understood to mean that the first recess 53 is arranged on one side next to a plane 23 which is perpendicular to the associated axis of rotation 14 in the middle of the contact region (No. 22 in FIG Fig. 1 ) is arranged between the bearing bore 51 and bearing journals

Incidentally, on the execution to the Fig. 1 to 3 with respect to the first embodiment, wherein like parts are identified by like reference numerals.

LIST OF REFERENCE NUMBERS

10

gear machine

11

gear

12

Side surface of the gear

13

pivot

14

axis of rotation

15

drive journal

20

first area

21

second area

22

Contact area between bearing bore and bearing journal

23

Level in the middle of the touch area

30

casing

31

main body

32

pressure connection

33

first lid

34

second lid

40

bearing body

41

location hole

42

feed

44

contact surface

45

third recess

50

bearing bush

51

bearing bore

52

groove

53

first recess / breakthrough

54

first female part

55

second socket part

Claims (12)

Gear machine (10), in particular pump or motor, with at least two toothed wheels (11) meshing with each other in external engagement, the toothed wheels (11) being surrounded by a housing (30), at least one toothed wheel (11) comprising at least one bearing pin (11). 13) which is rotatably received in an associated bearing bore (51) of the housing (30) with respect to a rotational axis (14), wherein the bearing bore (51) or the bearing pin (13) with a groove (52) is provided by the counterpart, bearing pin (13) or bearing bore (51) is covered,
characterized in that the groove (52) is formed endlessly circumferentially about the bearing journal (13), wherein on one side next to the groove (52) in the bearing bore (51) at least a first recess (53) is provided which with a closed feed channel (42) for supplying pressurized fluid. Gear machine according to claim 1,
characterized in that the bearing bore (51) in a separate bearing body (40) is arranged, which on a side surface (12) of the associated gear (11) is applied, wherein the feed channel (42) exclusively in the bearing body (40) is arranged. Gear machine according to claim 2,
characterized in that the feed channel (42) leads into the area of teeth of the gear wheel (11), so that there is a fluid exchange connection between the interdental spaces and the feed channel (42). Gear machine according to claim 3,
characterized in that the mouth opening of the feed channel on the associated gear (11) in the circumferential direction with respect to the axis of rotation (14) is wider than a tooth of the toothed wheel (11). Gear machine according to claim 1 or 2,
characterized in that the housing (30) has a pressure port (32), wherein the feed channel (42) is connected to the pressure port (32). Gear machine according to one of the preceding claims,
characterized in that the groove (52) extends in a plane which is perpendicular to the axis of rotation (14) of the associated journal (13), preferably having a constant cross-sectional shape. Gear machine according to one of the preceding claims,
characterized in that the bearing bore (51) is formed by a separate bearing bush (50), wherein the first recess is formed by a radial aperture (53) in the bearing bush (50), wherein the feed channel (42) in the remaining housing (30 ) is arranged. Gear machine according to claim 7,
characterized in that the opening (53) is in the form of a slot which is aligned parallel to the axis of rotation (14) of the associated journal (13). Gear machine according to claim 7 or 8,
characterized in that the bearing bush (50) is integrally formed, wherein the groove (52) is limited exclusively by the bearing bush (50). Gear machine according to claim 7 or 8,
characterized in that the bearing bush (50) has a first and a separate second bushing part (54; 55) which laterally delimit the groove (52). Gear machine (10), in particular pump or motor, with at least two toothed wheels (11) meshing with each other in external engagement, the toothed wheels (11) being surrounded by a housing (30), at least one toothed wheel (11) comprising at least one bearing pin (11). 13) rotatably received in an associated bearing bore (51) of the housing (30) with respect to a rotation axis (14),
characterized in that in the bearing bore (51) at least one first recess (53) is provided, which is connected to a closed feed channel (42) for supplying pressurized fluid, wherein the at least one first recess (53) is arranged on one side next to a plane , which is arranged perpendicular to the associated axis of rotation (14) in the middle of the contact region (22) between the bearing bore (51) and the bearing pin (13). Gear machine according to claim 11 having the features of the characterizing part of at least one of claims 2 to 5; 7 and 8.

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