EP3054161B1 - Method for operating a gear wheel pump and gear wheel pump - Google Patents

Description

The invention relates to a method for operating a gear pump according to the preamble of claim 1, a gear pump according to the preamble of

Claim 6 and a vehicle, in particular a commercial vehicle, and / or an internal combustion engine for performing the method and / or with the gear pump according to claim 17.

It is known to pump oil, in particular engine oil, of an oil circuit of a vehicle by means of a gear pump. The gear pump can be designed, for example, as an internal gear pump, in which at least one externally toothed gear meshes with at least one internally toothed gear. Such an internal gear pump is usually driven via the internal gear. Furthermore, it is also known to design a gear pump as an external gear pump, in which at least one externally toothed gear is in meshing engagement with at least one further externally toothed gear. The external gear pump is driven by means of at least one of these external gear wheels. The oil or the liquid to be pumped is conveyed by means of the tooth gaps between the individual teeth of the gear wheels. These tooth gaps form delivery chambers, by means of which the liquid to be delivered is conveyed in the direction of rotation of the respective gear wheel.

Furthermore, it is also known to axially divide the gears in an external gear pump or to arrange at least two gears one behind the other, as seen in the axial direction. The divided gears are then usually rotated relative to each other by half a tooth pitch. In this way, the amplitudes of pressure pulsations occurring during operation of the gear pump can be reduced, since the volume of the delivery chambers is reduced and the viscosity of the liquid when the liquid flows from one delivery chamber to the next Delivery chamber has a dampening effect. Too high amplitudes of the pressure pulsations can, for example, often overload the oil coolers, pressure relief valves and other components of the oil circuit in an oil circuit.

From the DE 197 46 768 A1 For example, a gear machine with an engine results from at least two gear paths, the gear wheels of which are guided with their hubs on at least two shafts rotatably mounted in the housing. The driven gearwheels of the at least two pairs of gearwheels are arranged together on one of the shafts and are non-rotatably coupled to this shaft via an external toothing formed on this shaft and an internal toothing formed in the hubs of the driven gearwheels. The external toothing of the shaft here consists of at least two toothed parts which are spaced apart from one another and have a tooth offset, which are each assigned to one of the driven gearwheels. In this way, it is easily and reliably ensured that the gearwheels are fixed on the common shaft offset from one another by half a tooth pitch.

The rotation of the divided gears relative to each other, however, has a negative effect on the suction capacity of the gear pump and thus also on the delivery capacity of the gear pump, in particular due to the flow of the liquid to be delivered from a delivery chamber to the adjacent delivery chamber. This is problematic, for example, when using a gear pump in an oil circuit of a vehicle in defined operating situations of the gear pump.

The publication GB 2 443 089 A , which is considered to be the closest prior art, discloses a gear pump with two gearwheels arranged one behind the other, seen in the axial direction, inside a housing, the one gearwheel being displaceable relative to the first gearwheel by means of an eccentric arrangement. Such a gear pump is also in the publications DE 1 231 563 A and GB 2 313 411 A disclosed.

It is therefore an object of the invention to provide a method for operating a gear pump and a gear pump, in which the operation of the gear pump is optimized in a simple and effective manner.

This object is solved by the features of the independent claims. Preferred developments are disclosed in the subclaims.

According to claim 1, a method for operating a gear pump, in particular for conveying oil in an oil circuit of a vehicle, is proposed, a delivery device having at least two gear wheels arranged in a housing, in particular externally toothed or designed as spur gears, being provided, by means of the gear wheels a liquid to be pumped can be conveyed from at least one housing inlet to at least one housing outlet, and wherein the gearwheels, viewed in the axial direction, are arranged one behind the other. According to the invention, an actuating device is provided by means of which the gearwheels are rotated relative to one another and / or displaced relative to one another depending on the pressure conditions in the interior of the housing, in particular depending on the suction vacuum at the housing inlet and / or depending on the liquid counterpressure at the housing outlet.

According to the invention, a fixing device is provided, by means of which at least one gear wheel, which forms an actuating gear wheel, is fixed on the housing such that it can be displaced and / or rotated relative to at least one other gear wheel. The actuating device has at least one spring element as a prestressing element, by means of which the adjusting gear can be prestressed into a basic position.

In this way, the operation of the gear pump is optimized in a simple and effective manner, since the gear wheels are now rotated relative to one another and / or displaced relative to one another depending on the pressure conditions in the interior of the housing. The pressure conditions inside the housing can be used to reliably determine whether a particularly high suction power of the gear pump and thus a particularly high delivery rate of the gear pump is currently required or not. The gear wheels can then be rotated and / or displaced relative to one another in such a way, for example, that the delivery capacity of the gear pump is particularly high or the amplitudes of the pressure pulsations of the gear pump are as low as possible. In addition, the gears can also be shifted to intermediate positions, which ensure sufficient delivery and at the same time reduced amplitudes of the pressure pulsations.

When viewed in the axial direction, the gearwheels can be arranged at a defined gap distance from one another in the housing. However, it is preferred if the gears arranged one behind the other are in contact with one another in order to realize a particularly compact construction.

The gearwheels are preferably arranged in the housing such that their axes of rotation are aligned essentially congruently or parallel to one another, in order to make the gearwheel pump particularly simple and effective. The gearwheels are further preferably rotated axially relative to one another and / or displaced relative to one another in the radial direction by means of the adjusting device as a function of the pressure conditions in the interior of the housing. In this way, the absorbency and the amplitudes of the pressure pulsations of the gear pump can be easily and effectively adjusted.

In a preferred method, the gearwheels have an essentially identical radial outer contour. The gearwheels are then arranged in alignment with one another in a basic position, seen in the axial direction. If the liquid back pressure at the housing outlet falls below at least a defined minimum value, the gearwheels are shifted from a position not corresponding to the basic position into the basic position by means of the adjusting device. In this basic position, the absorbency or suction power of the gear pump is greatest. By shifting the gearwheels into the basic position, it is reliably ensured that the delivery capacity of the gearwheel pump is at a maximum. In an oil circuit of a vehicle, this basic position of the gearwheels is advantageous, for example, when starting an internal combustion engine of the vehicle, since the oil pressure is built up particularly quickly and air bubbles are quickly broken down. When the internal combustion engine is started in this way, the liquid counterpressure at the housing outlet is particularly low. Likewise, the basic position in an oil circuit of a vehicle at low speeds of the gear pump and high oil temperatures is advantageous since, despite the low viscosity oil, so-called gap losses are better compensated for by the oil flowing between the delivery chambers and in the bearing points of the pump and the internal combustion engine. In this operating situation, the liquid back pressure at the housing outlet is also particularly low.

If the liquid counterpressure at the housing outlet does not fall below the at least one minimum value, the gearwheels arranged in the basic position are rotated relative to one another and / or displaced relative to one another by means of the adjusting device. In this way, the amplitudes of the pressure pulsations are reduced if the maximum absorbency or suction force of the gear pump is not required.

If the liquid counterpressure at the housing outlet exceeds at least a defined maximum value which is greater than the minimum value, the gearwheels are preferably shifted to a maximum position in which the gearwheels are arranged rotated relative to one another by half a tooth pitch. In this maximum position, the amplitudes of the pressure pulsations are particularly low. The liquid back pressure at the housing outlet is usually particularly high in an oil circuit of a vehicle at higher speeds of the gear pump.

To achieve the above-mentioned object, a gear pump, in particular for conveying oil in an oil circuit of a vehicle, is also proposed, with a delivery device which has at least two gear wheels arranged in a housing, in particular externally toothed and / or designed as spur gears, whereby by means of a liquid to be conveyed can be conveyed from the gearwheels from at least one housing inlet to at least one housing outlet, and the gearwheels, viewed in the axial direction, in particular with a defined gap distance, are arranged one behind the other. According to the invention, an actuating device is provided by means of which the gear wheels can be rotated relative to one another and / or displaced relative to one another depending on the pressure conditions in the interior of the housing, in particular depending on the suction vacuum at the housing inlet and / or depending on the liquid counterpressure at the housing outlet.

The advantages resulting from the gear pump according to the invention are identical to the advantages of the method according to the invention that have already been recognized, so that they are not repeated here.

According to the invention, a fixing device is provided, by means of which at least one gear wheel, which forms an actuating gear wheel, is fixed on the housing such that it can be displaced and / or rotated relative to at least one other gear wheel. In this way, the gearwheels can be rotated and / or displaced relative to one another in a particularly simple manner.

According to the invention, the adjusting device has at least one prestressing element, by means of which the adjusting gearwheel can be prestressed into a basic position. In this way, the adjusting gear can be easily and reliably shifted into the basic position, since it is pressed or pretensioned into this basic position by means of the pretensioning element. The biasing element is preferably formed by a spring element, in particular by a torsion spring, in order to make the biasing element functionally reliable and simple.

The prestressing element further preferably interacts with a stop, in particular with at least one stop element, which prevents rotation and / or displacement of the adjusting gear arranged in the basic position in at least one defined direction. This can result in unwanted twisting and / or displacement of the adjusting gear in at least one defined direction can be reliably prevented.

More preferably, the adjusting gear arranged in the basic position rotates and / or rotates relative to the at least one other gear in the housing at defined pressure conditions in the housing, starting from the basic position. By this displacement and / or rotation of the adjusting gear, the biasing element is then tensioned with the build-up of a restoring force. In this way, the rotation and / or displacement of the gear wheels relative to one another can be implemented particularly simply and reliably as a function of the pressure conditions in the interior of the housing. In particular, it is not necessary to regulate or control the rotation and / or displacement of the gearwheels in a complex and susceptible manner to failure by means of a regulating and / or control device. The gear pump is therefore particularly cost-effective.

A stop element is preferably provided, by means of which the displacement and / or rotation of the adjusting gear arranged in the basic position can be limited to a defined dimension. In this way, it is reliably and simply ensured that the actuating gear can only shift to a defined extent relative to the at least one other gear.

Specifically, the gear pump can be designed, for example, as an internal gear pump, the at least two gear wheels being formed by externally toothed gear wheels which are in meshing engagement with at least one internally toothed gear element. The internally toothed gear element or an externally toothed gear element, which does not form an actuating gear, preferably forms a drive gear for driving the internal gear pump in order to be able to drive the gear pump in a particularly simple manner.

The fixing device preferably has a fixing element, by means of which the adjusting gear is fixed to the housing such that it can be displaced relative to the housing, the adjusting gear being rotatably fixed to the fixing element while forming a first axis of rotation, the fixing element essentially forming a arranged parallel to the first axis of rotation, the second axis of rotation is rotatably fixed to the housing, and wherein the adjusting gear can be displaced relative to the housing by rotating the fixing element. That way the adjusting gear can be shifted and / or rotated in a particularly simple and reliable manner relative to the at least one other gear. It is preferably provided that the fixing element is essentially Z-shaped in order to make the fixing element functionally optimized.

The biasing element is further preferably tensioned by rotating the fixing element in a first direction of rotation. The biasing element is then relaxed by rotating the fixing element in a second direction of rotation opposite to the first direction of rotation. In this way, the adjusting gear can be pretensioned into the basic position in a particularly simple manner by means of the pretensioning element. It is preferably provided that the prestressing element is fixed with an end region to a region of the fixing element protruding from the housing in order to be able to fasten the prestressing element to the fixing element in a particularly simple manner.

As an alternative to the design as an internal gear pump, the gear pump can also be designed as an external gear pump, the at least two gear wheels being formed by externally toothed gear wheels and forming drive gear wheels for driving the external gear pump, and each of these drive gear wheels in meshing engagement with a corresponding externally toothed gear wheel.

The fixing device preferably has a drive shaft rotatably fixed to the housing for driving the drive gearwheels, at least one drive gearwheel being non-rotatably connected to the drive shaft, at least one drive gearwheel forming the actuating gearwheel being fixed axially rotatable on the drive shaft relative to the drive shaft. and wherein the drive shaft is connected to the actuating gear by means of the biasing element in a torque-transmitting manner. In this way, the adjusting gear can be fixed in a particularly simple manner so that it can be rotated relative to the other gear.

The biasing element is preferably tensioned in a first direction of rotation by rotating the adjusting gearwheel relative to the drive shaft. The biasing element is then relaxed by rotating the actuating gear relative to the drive shaft in a second direction of rotation opposite to the first direction of rotation. Thus, the adjusting gear can also be biased into the basic position particularly easily by means of the biasing element. It is preferably provided that the prestressing element, in Seen in the axial direction, is arranged between the drive gears in order to realize a particularly compact design. Alternatively and / or additionally, the prestressing element can also be arranged between the adjusting gearwheel and a housing wall or protrude from the housing.

Furthermore, a vehicle, in particular a commercial vehicle, and / or an internal combustion engine for carrying out the method according to the invention and / or with the gear pump according to the invention is also claimed. The advantages resulting from this are identical to the advantages of the method according to the invention and / or the gear pump according to the invention that have already been recognized, so that they are not repeated here. The internal combustion engine can for example also be designed as a stationary internal combustion engine or as a marine internal combustion engine.

The advantageous embodiments and / or further developments of the invention explained above and / or reproduced in the subclaims can - apart from, for example, in the case of clear dependencies or incompatible alternatives - be used individually or in any combination with one another.

The invention and its advantageous training and / or further developments as well as their advantages are explained in more detail below only with reference to drawings.

Fig. 1

in einer Ansicht von oben eine erfindungsgemäße Innenzahnradpumpe mit geöffnetem Gehäuse in einer ersten Betriebssituation;

Fig. 2

in einer Darstellung gemäß Fig. 1 die Innenzahnradpumpe in einer zweiten Betriebssituation;

Fig. 3

in einer schematischen Schnittdarstellung eine Stelleinrichtung der Innenzahnradpumpe;

Fig. 4

eine schematische Darstellung, anhand der die Funktionsweise der Stelleinrichtung erläutert wird;

Fig. 5

in einer Darstellung von oben eine erfindungsgemäße Außenzahnradpumpe mit geöffnetem Gehäuse in einer ersten Betriebssituation;

Fig. 6

in einer Darstellung gemäß Fig. 5 die Außenzahnradpumpe in einer zweiten Betriebssituation; und

Fig. 7

in einer schematischen Schnittdarstellung eine Stelleinrichtung der Außenzahnradpumpe.

Show it:

Fig. 1

in a view from above, an internal gear pump according to the invention with an open housing in a first operating situation;

Fig. 2

in a representation according to Fig. 1 the internal gear pump in a second operating situation;

Fig. 3

in a schematic sectional view of an actuating device of the internal gear pump;

Fig. 4

a schematic representation, based on which the operation of the actuating device is explained;

Fig. 5

in an illustration from above, an external gear pump according to the invention with an open housing in a first operating situation;

Fig. 6

in a representation according to Fig. 5 the external gear pump in a second operating situation; and

Fig. 7

in a schematic sectional view of an actuator of the external gear pump.

In Fig. 1 a gear pump designed as an internal gear pump 1 is shown here by way of example. The internal gear pump 1 has a housing 3, which in Fig. 1 is shown open. The housing 3 here has a housing inlet 5 and a housing outlet 7. By means of the housing inlet 5 and the housing outlet 7, the internal gear pump 1 can be connected, for example, to an oil circuit of a vehicle, so that the oil to be conveyed by means of the internal gear pump 1 reaches the interior of the housing 3 via the housing inlet 5 and out of the housing again via the housing outlet 7 3 exits.

As in Fig. 1 Is further shown, the internal gear pump 1 has an internal gear arranged in the interior of the housing 3, here exemplified as a spur gear 9, which forms a drive gear for driving the internal gear pump 1. The internally toothed spur gear 9 is in mesh with several, here exemplified with two externally toothed, also designed as spur gears 11, 13 gears. The externally toothed spur gears 11, 13 are here, for example, identical or of identical construction and, in the axial direction x ( Fig. 3 ) seen, arranged one behind the other in the housing 3 with a defined gap distance. To drive the internal gear pump 1, the internally toothed spur gear 9 is driven in rotation by means of a suitable drive device, not shown in the figures. The externally toothed spur gears 11, 13 which are in meshing engagement with the internally toothed spur gear 9 are then likewise driven in rotation by means of the internally toothed spur gear 9. In this way, the liquid to be conveyed is conveyed via tooth spaces 15 of the externally toothed spur gears 11, 13 forming the conveying chambers from the housing inlet 5 to the housing outlet 7.

According to Fig. 1 the externally toothed spur gear 13 is axially rotatable, for example, on an axis 19. The axis 19 is here, for example, rigid or immovable fixed to the housing 3. The externally toothed spur gear 11 is exemplified here by means of an adjusting device 21 ( Fig. 3 ) can be displaced and rotated relative to the externally toothed spur gear 13 on the housing 3. The externally toothed spur gear 11 can, for example, by means of the adjusting device 21 in a Fig. 2 shown basic position are arranged, in which the externally toothed spur gears 11, 13, seen in the axial direction x or in plan view, are arranged in alignment with each other. The axes of rotation of the spur gears 11, 13 are then aligned congruently to one another. In addition, the externally toothed spur gear 11 can also be arranged here, for example, in a maximum position in which the externally toothed spur gears 11, 13 are rotated relative to one another by half a tooth pitch. In Fig. 1 the externally toothed spur gear 11 is arranged in a position between the basic position and the maximum position. The axes of rotation of the spur gears 11, 13 are here, for example, aligned parallel to one another.

How out Fig. 3 As can be seen, the adjusting device 21 has a fixing device 23, by means of which the gear wheel 11, which forms an adjusting gear wheel, is fixed on the housing 3 such that it can be displaced or rotated relative to the housing 3 and thus also to the spur gear 13. The fixing device 23 here comprises, for example, an essentially Z-shaped fixing element 25 which has an axis 27 which forms a first axis of rotation A ₁ and on which the adjusting gear 11 is fixed in an axially rotatable manner. In addition, the fixing element 25 also has an axis 29 which forms a second axis of rotation A ₂ and by means of which the fixing element 25 is rotatably fixed to the housing 3. The axes 27, 29 are offset from one another such that the second axis of rotation A _{2 is arranged} parallel to the first axis of rotation A ₁ . By rotating the fixing element 25 about the second axis of rotation A ₂ , the adjusting gear 11 can therefore be rotated and displaced relative to the spur gear 13.

According to Fig. 3 the actuating device 21 also has a biasing element, which is designed here, for example, as a torsion spring 31, by means of which the setting gearwheel 11 is moved into the basic position ( Fig. 2 ) is biased. The torsion spring 31 is exemplified here by rotating the fixing element 25 in a first direction of rotation R ₁ ( Fig. 4 ) around the second axis of rotation A ₂ . By rotating the fixing element 25 about the second axis of rotation A ₂ in a second direction of rotation R ₂ (opposite to the first direction of rotation ₎ Fig. 4 ) the torsion spring 31 can be relaxed. The torsion spring 31 is here, for example, with an end region 33 on a protruding from the housing 3 End region 35 of the fixing element 25 and fixed immovably or rigidly at a fixing point 39 on the vehicle side with a second end region 37.

Furthermore, the adjusting element 25 is here, for example, by means of the torsion spring 31 against an in Fig. 4 schematically shown stop element 41 biased. The stop element 41 prevents rotation and / or displacement of the adjusting gear 11 arranged in the basic position in the first direction of rotation R ₂ . In addition, the torsion spring 31 is designed here, for example, in such a way that the fixing element 25 rotates in the housing 3 in the first direction of rotation R ₁ at defined pressure conditions. As a result of this rotation, the torsion spring 31 is tensioned while building up a restoring force.

How out Fig. 4 Furthermore, the adjusting device 21 also has a stop element 43, by means of which the rotation of the fixing element 25 in the first direction of rotation R ₁ and thus also the displacement or rotation of the adjusting gear 11 from the basic position is limited in such a way that the adjusting Gear 11 can only be moved to the maximum position.

In the 5 to 7 a second embodiment of the gear pump according to the invention is shown. The gear pump is designed here, for example, as an external gear pump 45. The external gear pump 45 has a plurality of, here exemplarily two, external gear toothed gears designed here as spur gears 47, 49 for driving the external gear pump 45. Each of these spur gears 47, 49 is here, for example, in meshing engagement with a corresponding gear, which is likewise designed here as a spur gear 51. The spur gears 51 are axially rotatable, for example, on an axis 52. The axis 52 is fixed, for example, rigidly or immovably on the housing 3. Furthermore, the spur gears 47, 49, 51 are designed here to be identical or structurally identical.

As in Fig. 7 is shown, the fixing device 23 here has a drive shaft 53 rotatably fixed to the housing 3 for driving the spur gears 47, 49. The spur gear 47 is connected, for example, in a rotationally fixed manner to the drive shaft 53. The spur gear 49, which forms an actuating gear, is fixed axially rotatably on the drive shaft 53 in relation to the drive shaft 53. Furthermore, the two spur gears 47, 49 are connected here in a torque-transmitting manner by means of a biasing element designed as a torsion spring 55. The torsion spring 55 is an example here, in the axial direction x seen, arranged between the spur gears 47, 49. The torsion spring 55 is tensioned in a first direction of rotation by rotating the adjusting gear 49 relative to the drive shaft 53 and thus also relative to the gear 47. In addition, the torsion spring 55 is relaxed by rotating the adjusting gear 49 relative to the drive shaft 53 in a second direction of rotation opposite to the first direction of rotation.

Reference list

1

Internal gear pump

3rd

casing

5

Housing inlet

7

Housing outlet

9

internally toothed spur gear

11

externally toothed spur gear

13

externally toothed spur gear

15

Tooth gap

19th

axis

21

Actuator

23

Fixing device

25th

Fixing element

27

axis

29

axis

31

Torsion spring

33

first end area

35

End area

37

second end area

39

Determination point

41

Stop element

43

Stop element

45

External gear pump

47

Spur gear

49

Spur gear

51

Spur gear

52

axis

53

drive shaft

55

Torsion spring

A ₁

first axis of rotation

A ₂

second axis of rotation

R ₁

first direction of rotation

R ₂

second direction of rotation

Claims (17)

1. Method for operating a gear pump, a conveying device with at least two gearwheels (11, 13, 47, 49) which are arranged in a housing (3) being provided, it being possible for a liquid to be conveyed to be conveyed by means of the gearwheels (11, 13, 47, 49) starting from at least one housing inlet (5) towards at least one housing outlet (7), the gearwheels (11, 13, 47, 49) being arranged behind one another as viewed in the axial direction (x), and an actuating device (21) being provided, by means of which the gearwheels (11, 13, 47, 49) are rotated relative to one another and/or are moved relative to one another, in such a way that a fixing device (23) is provided, by means of which at least one gearwheel (11, 49) which configures an actuating gearwheel is fixed on the housing (3) such that it can be moved and/or rotated relative to at least one other gearwheel (13, 47), characterized in that the gearwheels (11, 13, 47, 49) are rotated relative to one another and/or are moved relative to one another by means of the actuating device (21) in a manner which is dependent on the pressure conditions in the interior of the housing (3), the actuating device (21) having at least one spring element as prestressing element (31), by means of which the actuating gearwheel (11, 49) can be prestressed into a basic position.
2. Method according to Claim 1, characterized in that the gearwheels (11, 13, 47, 49) are arranged in the housing (3) in such a way that their rotational axes are oriented substantially congruently or in parallel with respect to one another, and/or in that the gearwheels (11, 13, 47, 49) are rotated axially relative to one another and/or are moved in the radial direction relative to one another by means of the actuating device (21) in a manner which is dependent on the pressure conditions in the interior of the housing (3).
3. Method according to Claim 1 or 2, characterized in that the gearwheels (11, 13, 47, 49) have a substantially identical radial outer contour, in that, in the basic position, the gearwheels (11, 13, 47, 49) are arranged aligned with respect to one another, as viewed in the axial direction (x), and in that, if the liquid back pressure at the housing outlet (7) undershoots at least one defined minimum value, the gearwheels (11, 13, 47, 49) are moved by means of the actuating device (21) from a position which does not correspond to the basic position into the basic position.
4. Method according to Claim 3, characterized in that, if the liquid back pressure at the housing outlet (7) does not undershoot the at least one minimum value, the gearwheels (11, 13, 47, 49) which are arranged in the basic position are rotated relative to one another and/or are moved relative to one another by means of the actuating device (21).
5. Method according to Claim 4, characterized in that, if the liquid back pressure at the housing outlet (7) exceeds at least one defined maximum value which is configured to be greater than the minimum value, the gearwheels (11, 13, 47, 49) are moved into a maximum position, in which the gearwheels (11, 13, 47, 49) are arranged such that they are rotated relative to one another by half their tooth spacing.
6. Gear pump with a conveying device which has at least two gearwheels (11, 13, 47, 49) which are arranged in a housing (3), it being possible for a liquid to be conveyed to be conveyed by means of the gearwheels (11, 13, 47, 49) starting from at least one housing inlet (5) towards at least one housing outlet (7), the gearwheels (11, 13, 47, 49) being arranged behind one another as viewed in the axial direction (x), an actuating device (21) being provided, by means of which the gearwheels (11, 13, 47, 49) can be rotated relative to one another and/or can be moved relative to one another, in such a way that a fixing device (23) is provided, by means of which at least one gearwheel (11, 49) which configures an actuating gearwheel is fixed on the housing (3) such that it can be moved and/or rotated relative to at least one other gearwheel (13, 47), characterized in that the gearwheels (11, 13, 47, 49) can be rotated relative to one another and/or can be moved relative to one another by means of the actuating device (21) in a manner which is dependent on the pressure conditions in the interior of the housing (3), the actuating device (21) having at least one spring element as prestressing element (31), by means of which the actuating gearwheel (11, 49) can be prestressed into a basic position.
7. Gear pump according to Claim 6, characterized in that the prestressing element (31) is formed by way of a torsion spring.
8. Gear pump according to Claim 6 or 7, characterized in that the prestressing element (31) interacts with a stop (41), in particular with at least one stop element, which prevents a rotation and/or movement of the actuating gearwheel (11, 49) which is arranged in the basic position in at least one defined direction.
9. Gear pump according to one of Claims 6 to 8, characterized in that, in the case of defined pressure conditions in the housing (3), the actuating gearwheel (11, 49) which is arranged in the basic position is moved and/or rotated relative to the at least one other gearwheel (13, 47), and in that the prestressing element (31) can be stressed with a build-up of a restoring force by way of the said movement and/or rotation of the actuating gearwheel (11, 49).
10. Gear pump according to one of Claims 6 to 9, characterized in that a stop element (43) is provided, by means of which the movement and/or rotation of the actuating gearwheel (13, 47) which is arranged in the basic position can be limited.
11. Gear pump according to one of Claims 6 to 10, characterized in that the gear pump is configured as an internal gear pump (1), the at least two gearwheels (11, 13) being formed by way of externally toothed gearwheels which are in tooth engagement with at least one internally toothed gearwheel element (9).
12. Gear pump according to Claim 11, characterized in that the fixing device (23) has a fixing element (25), by means of which the actuating gearwheel (11) is fixed on the housing (3) such that it can be moved relative to the housing (3), the actuating gearwheel (11) being fixed rotatably on the fixing element (25) with the configuration of a first rotational axis (A₁), the fixing element (25) being fixed rotatably on the housing (3) with the configuration of a second rotational axis (A₂) which is arranged substantially parallel to the first rotational axis (A₁), and it being possible for the actuating gearwheel (11) to be moved by way of rotation of the fixing element (25) relative to the housing (3), it preferably being provided that the fixing element (25) is of substantially Z-shaped configuration.
13. Gear pump according to Claim 12, characterized in that the prestressing element (31) can be stressed by way of rotation of the fixing element (25) in a first rotational direction (R₁), and in that the prestressing element (31) can be relieved by way of rotation of the fixing element (25) in a second rotational direction (R₂) which is opposed to the first rotational direction (R₁), it preferably being provided that the prestressing element (31) is fixed by way of an end region (33) on a region (35) of the fixing element (25), which region (35) protrudes out of the housing (3).
14. Gear pump according to one of Claims 6 to 10, characterized in that the gear pump is configured as an external gear pump (45), the at least two gearwheels (47, 49) being formed by way of externally toothed gearwheels and configuring drive gearwheels for driving the external gear pump (45), and each of the said drive gearwheels (47, 49) being respectively in tooth engagement with a corresponding externally toothed gearwheel (51).
15. Gear pump according to Claim 14, characterized in that the fixing device (23) has a drive shaft (53) which is fixed rotatably on the housing (3) for driving the drive gearwheels (47, 49), at least one drive gearwheel (47) being connected fixedly to the drive shaft (53) so as to rotate with it, at least one drive gearwheel (49) which configures the actuating gearwheel being fixed on the drive shaft (53) such that it can be rotated axially relative to the drive shaft (53), and the drive gearwheels (47, 49) being connected in a torque-transmitting manner by means of the prestressing element (31).
16. Gear pump according to Claim 15, characterized in that the prestressing element (31) can be stressed by way of rotation of the actuating gearwheel (49) relative to the drive shaft (53) in a first rotational direction, and in that the prestressing element (31) can be relieved by way of rotation of the actuating gearwheel (49) relative to the drive shaft (53) in a second rotational direction which is opposed to the first rotational direction.
17. Vehicle with a gear pump according to one of Claims 6 to 16.

Images