DE10037891A1 - Gerotor pump with eccentric adjustment - Google Patents

Abstract

Gerotor pump with delivery volume adjustment, the pump comprising: DOLLAR A a) a housing (1, 2), DOLLAR A b) a rotatably mounted outer rotor (5) which is accommodated by the housing (1, 2) and has an internal toothing (5i) , DOLLAR A c) a rotatably mounted inner rotor (4), which has an external toothing (4a) which meshes with the internal toothing (5i), the internal toothing (5i) having at least one tooth more than the external toothing ( 4a) and the internal toothing (5i) and the external toothing (4a) form mutually sealed, expanding and compressing delivery cells (7), DOLLAR A d) in the housing (1, 2) arranged laterally in the area of the delivery cells (7) low pressure and high pressure openings , which are separated from one another by webs, DOLLAR A e) an eccentric ring (11) which is rotatably mounted in the housing (1, 2) about an eccentric ring axis of rotation (4 ') and one of the rotors (4, 5) about a rotor axis of rotation ( 5 ') rotatable supports, the rotor axis of rotation (5 ') and the eccentric ring axis of rotation (4') are eccentric to each other, DOLLAR A f) and an adjustment gear which is coupled to the eccentric ring (11) and an adjusting force in a torque acting on the eccentric ring (11) converts and comprises an actuator (20) which is accommodated in the housing (1, 2) to move back and forth and on which the adjusting force acts, DOLLAR A characterized in that DOLLAR A g) the eccentric ring (11) with one around Eccentric ring axis of rotation (4 ') rotatably mounted rocker (14, 15) ...

Description

The invention relates to a gerotor pump, the specific delivery volume is adjustable. The specific delivery volume is based on a pump speed related pump delivery volume [delivery volume / pump speed]. The Adjustment is caused by a change in the angular position of an eccentric ring a pivot bearing of one of at least two in engagement with each other Conveyor wheels of the gerotor pump forms.

Known gerotor pumps have a system-specific constant Delivery volume because the geometry of the displacement cells of the pumps is not can be changed. The constancy of the specific funding volume results from automatically a proportionality of the delivery volume of the pump over the speed, as long as the filling level of the conveyor cells is 100%. In many use cases, however this proportionality disturbing. In the case of a press, for example, there is one for rapid traverse high supply quantity of pressure oil necessary, but in the final phase of the work stroke only high pressure is required, the demand for oil production volume drops to zero. Since the drive speed usually remains constant, it is created under high pressure standing oil flow surplus, which flows back into an oil tank with energy loss.

An excess of oil flow is also disruptive, for example, for engine lubrication pumps and Oil supply pumps for automatic transmissions of motor vehicles. This Units need at low engine speed and therefore lower Pump speed, especially at idle, a minimum flow rate and at high Speed a minimum oil pressure, but the oil quantity requirement is at higher speed far below the proportionality line.  

In gerotor pumps, as the invention relates to them, there is Possibility of an eccentricity between an axis of rotation of an inner rotor and an axis of rotation of an outer rotor of the pump, opposite one Pump housing and thus opposite the inlet and outlet openings in the housing can be changed. For this, one of the rotors, preferably the outer rotor, rotatably mounted in an eccentric ring. The eccentric ring can be rotated in the housing arranged, and the angular position of the eccentric ring is relative to the housing adjustable. For a desired in practical use Flow adjustment up to close to zero is an angle adjustment the eccentricity over an angular range around one of the rotor axes of rotation or Eccentric ring axis of rotation of 90 ° advantageous. It should therefore be possible to Eccentric ring for adjusting the eccentricity of the rotor axes of rotation by up to 90 °, d. H. to displace large circumferential paths. To generate an adjusting force for the Adjustment of the eccentric ring is usually an adjusting piston with part of the Oil from the high pressure side of the pump. The adjustment force generated in this way is by means of an adjusting gear in the rotary movement of the eccentric ring converted. The adjusting force is counteracted by a counterforce that acts on you If the adjustment force decreases, the eccentric ring is turned back to the angular position for maximum specific funding volume. A disadvantage of known pumps is that the spring members used to generate the counterforce have great distances drive through, namely via the up to 90 ° angle adjustment of the eccentric ring, what because of an advantageously soft spring characteristic to problems in the design of the Spring links leads.

From EP 0 284 226 A2 a gerotor pump with two eccentric rings is known rotated in opposite directions to adjust the specific delivery volume in the housing become. A control piston with the pump pressure is used to generate the adjusting force applied. The linear movement of the control piston is by means of a Control piston rigidly attached rack via an intermediate gear on one of the Transfer eccentric rings. For this purpose, the intermediate gear meshes axially with one an outer bearing surface of the eccentric ring formed on the eccentric ring Toothing. By means of a branch from the intermediate gear the other  Eccentric ring turned in the same way in opposite directions. A counterforce is created by a pressure spring acting on the control piston, with a reverse rotation of the Eccentric rings is only partially caused by this compression spring. In addition to the A torsion spring is provided for the compression spring.

An object of the invention is to provide a gerotor pump with a simple and to create a compact mechanism for adjusting the delivery volume.

This object is solved by the subject matter of claim 1.

A gerotor pump as per the invention has at least one housing, a rotatably mounted outer rotor received by the housing with a Internal teeth, a rotatably mounted inner rotor with external teeth, at least one low pressure opening and at least one high pressure opening, one Eccentric ring, a reciprocating actuator, preferably a linear movable actuator, and an adjustment gear for transmitting actuating movements of the actuator on the eccentric ring. The external teeth of the inner rotor meshes with the internal teeth of the outer rotor. Preferably only one of the driven both rotors and drives the other of the rotors through the tooth mesh with on. The driven rotor is supplied with the speed of one by the pump Unit or a derived, increased or reduced speed driven. The rotor can, for example, directly on an engine crankshaft or Input shaft of an automatic transmission sit or only via a branching off Gears are driven. The axes of rotation of the two rotors run parallel in a distance from each other, d. H. they are eccentric to each other. The internal toothing of the outer rotor has at least one tooth more than the external toothing of the inner rotor. It preferably has exactly one more tooth. The meshing of the two rotors is such that between the external teeth and the Internal toothing conveyor cells are formed by tooth flank contact and at a point of minimal tooth meshing by touching the tooth head against each other are sealed, with the slightest tooth engagement also at the point  certain game can remain. At the point of deepest meshing, one can Sickle provide a seal.

The specific delivery volume of the pump is adjusted by rotating the Eccentricity of the two rotors around an axis, preferably around one of the two Rotor rotary axes. By rotating the eccentricity, the angular position of the Place deepest tooth engagement relative to the at least one low pressure opening and which adjusts at least one high pressure opening. The at least one Low-pressure opening and the at least one high-pressure opening are advantageous formed in the housing as fixed openings. In principle it would be however, it is also possible to change the positions of these openings relative to the housing to design, with any changes in position of these openings, in particular Changes in the angular position are coordinated with the eccentricity adjustment. The eccentric ring is rotatable by the housing about an eccentric ring axis of rotation stored and itself forms the rotary bearing for one of the rotors, preferably for the outer rotor. Accordingly, the eccentric ring has a bearing surface over which it itself is rotatably mounted, and a tread that a plain bearing surface or Support bearing surface for a roller bearing of the one rotatably supported by the eccentric ring Rotors forms.

The actuator is preferably an actuator piston, which is rigid in a cylinder with the Pump housing connected or preferably by the pump housing itself is formed, is received back and forth straight. The piston will preferably constantly pressurized with the high pressure side of the pump, by diverting part of the fluid delivered by the pump into the cylinder. The fluid is preferably a hydraulic fluid, in particular a lubricating oil, for example for an internal combustion engine, or a working oil for a Working unit, for example an automatic transmission or a press. The pump preferably forms the main pump for supplying the motor or other Working unit. The hydraulic fluid can also be water, for example.  

According to the invention, an adjusting force for rotating the eccentric ring over a Swivel arm, d. H. via a swing arm on the eccentric ring transfer. An adjustment path of the actuator is determined by the swing arm according to the length of the swing arm formed by the rocker into one on the bearing surface or Tread of the eccentric ring translates the measured displacement of the eccentric ring, the is longer than the actuator travel. With the same travel ranges, they become larger Changes in the angular position of the eccentric ring than in the prior art known solutions achieved.

The rocker is non-rotatably connected to the eccentric ring, i. H. the transfer the swinging motion of the rocker is slip-free on the eccentric ring, which also means a transmission via a slip-free transmission is not excluded from the outset should be. However, the eccentric ring is preferably completely rigid with the rocker connected. The eccentric ring and the rocker are particularly preferred as one only stiff body.

The adjustment gear preferably comprises at least the actuator Cam gear with at least one cam joint and the rocker. In preferred In embodiments, the adjustment gear has only a single cam joint, in which the preferably linear actuating movements of the actuator directly into the Swing movements of the swing arm can be converted.

The actuating movements of the actuator can by means of a crank-like Adjusting gear are transferred into the swiveling movements of the eccentric ring, by a thrust member as in a crank mechanism with a rotating body, preferably is directly coupled to the swing arm. A conversion of linear movements in rotary movements by means of a link guide instead of a shaft joint basically also conceivable. Preferably, the cam mechanism with the at least one cam joint, however, formed by a gear transmission. The Gear transmission in this case preferably comprises a rack Thrust link and a gear wheel meshing with the rack. The gear can only be coupled to the rocker via another gear link.  

However, the gearwheel is preferably torsionally rigid directly with the rocker connected and is by or on one to the eccentric ring axis of rotation concentric spigot formed. If the cam mechanism is a crank mechanism or a Sliding cam gear with a link guide would be one with the swing arm or an intermediate rotating body connected eccentric to the eccentric ring axis of rotation to arrange.

Although the delivery volume adjustment, for example, is fixed to the pump speed coupled or on the basis of measurement signals that indicate the delivery volume and / or the Represent pump pressure, can be made by motor, is a automatic volume control preferred. With the self-employed Delivery volume control is the adjusting force, which is preferably applied to it of an actuating piston with the pump pressure is constantly generated Restoring force of a restoring element opposed as a counterforce. The restoring force can be generated by compressing a compressible pressure fluid that is in a Pressure chamber is compressed by the piston movement. It is preferred however, by tensioning a mechanical reset element, in particular a spring or a spring system. A momentary difference between the adjustment force and Restoring force determines the direction of movement of the actuator and thus the Direction of rotation of the eccentric ring. The actuator, the Adjustment gear and thus also the eccentric ring in the one just taken Equilibrium position.

If the pusher is designed as a toothed rack, the teeth of the pusher are and the restoring force generating spring member or said pressure chamber in Direction of movement of the thrust link not seen one behind the other, but preferably arranged to overlap each other, thereby creating a short and therefore rigid Construction of the variable speed gear is obtained.

A thrust member designed as a rack is preferably by a cylindrical body with the toothing formed on a cylindrical surface. In principle, however, the cylindrical body can also have one or more edges  exhibit. The cylindrical body is particularly preferred over its entire length rotationally symmetrical. Advantageously, a receiving bore in one Receiving body for the thrust member, preferably a receiving bore in the Pump housing, also simply rotationally symmetrical or circular cylindrical with possibly different diameters in the axial direction. The thrust member is particularly preferred by a hollow cylindrical body formed, which has an open end. In this case, the reset element is in the hollow cylindrical thrust member added.

The cylindrical body advantageously also forms the actuating piston at the same time. is the reset member is received in the hollow cylindrical body, so the Adjusting piston formed at the end of the cylindrical body, the open end opposite. A spring link or the pressure fluid of a pneumatic In this case, the resetting element can easily be against a front end face of the press hollow cylindrical body, which also forms a piston crown at the same time. A particularly stable straight guide of a thrust member designed as a rack results from the fact that the thrust link has one on each side of the toothing Sliding guide surface forms. To one side of the gearing is this Sliding guide surface preferably formed by the actuating piston itself.

An embodiment of the invention is explained below with reference to figures. The features disclosed on the basis of the exemplary embodiment each form individually and in each of the disclosed combinations of features the subjects of the claims in preferred directions further. Show it:

FIG. 1a is a gear pump with an adjustable eccentric ring in an initial position,

FIG. 1b, the gear pump of FIG. 1 in an end position,

Fig. 2, the ring gear pump in an exploded view,

Fig. 3, the gerotor pump in a longitudinal section and

Fig. 4, the gerotor pump in a cross section.

FIGS. 1a and 1b show a gear pump in a cross section. The gerotor pump has an inner rotor 4 with an outer toothing 4 a and an outer rotor 5 with an inner toothing 5 i, which form a ring gear set. The external toothing 4 a has one tooth less than the internal toothing 5 i. The inner rotor 4 is rotationally connected to a rotatably driven shaft in the main example, the rotor 4 is shrink-fitted onto a pin 3 of the shaft. Axial connecting channels are provided between the shaft shrink fit and the inner rotor 4 . Both the shaft journal 3 and thus the inner rotor 4 and the outer rotor 5 are rotatably mounted in a housing part 1 of a pump housing. The pump housing is in two parts, as can be seen for example in FIG. 2, with a housing part 1 and a housing part 2 , which are placed against one another and fastened in the axial direction of the shaft journal 3 .

An axis of rotation 4 ′ of the inner rotor 4 runs parallel, spaced apart, ie eccentrically, to an axis of rotation 5 ′ of the outer rotor 5 . The eccentricity, ie the distance between the two axes of rotation 4 'and 5 ', is designated by "e".

The inner rotor 4 and the outer rotor 5 form a fluid delivery space between them. This fluid delivery space is subdivided into delivery cells 7 , 7 'which are sealed off from one another in a pressure-tight manner. The individual feed cells 7 , 7 'are each formed between two successive teeth of the inner rotor 4 and the inner toothing 5 i of the outer rotor 5 , by two successive teeth of the inner rotor 4 making head or flank contact with two successive, opposing teeth of the inner toothing 5 i have. In principle, there may also be a slight play between the tooth heads at the point of minimal tooth engagement, in which case the fluid conveyed, preferably a hydraulic fluid, forms a sealing film between the tooth heads located opposite one another.

The conveying cells 7 become increasingly larger in the direction of rotation D from a location of deepest tooth engagement to a location with the lowest tooth engagement, in order to subsequently decrease again from the location of the lowest tooth engagement. The increasing delivery cells 7 form a low pressure side and the decreasing delivery cells 7 'a high pressure side. The low pressure side is connected to a pump inlet and the high pressure side is connected to a pump outlet. In the housing 1 , 2 , kidney-shaped groove openings adjoining the conveyor cells 7 and the conveyor cells 7 'are excluded. At least one of these openings covers conveyor cells 7 on the low pressure side and accordingly forms a low pressure opening, and at least one other of these openings covers conveyor cells 7 'on the high pressure side and accordingly forms a high pressure opening. In the area of the deepest tooth mesh and in the area of the lowest tooth mesh, the housing forms sealing webs between the adjacent high and low pressure openings. When the one of the rotors 4 and 5 is driven in rotation, fluid is drawn in by the expanding delivery cells 7 on the low-pressure side, transported via the location of the least amount of tooth engagement and discharged again on the high-pressure side under higher pressure. In the exemplary embodiment, the pump receives its rotary drive from a rotary drive element which is formed by a drive shaft. The shaft journal 3 of this drive shaft is rotatably supported in the housing 1 , 2 , as can be seen in FIG. 3. In a preferred use of the pump as a lubricating oil or motor oil pump for an internal combustion engine, in particular a reciprocating piston engine, the drive shaft is usually directly the crankshaft or the output shaft of a transmission, the input shaft of which is the crankshaft of the engine. It can also be formed by a balancer shaft for force balancing or torque balancing of the motor.

In order to be able to change the specific delivery volume, the outer rotor 5 is accommodated in an eccentric ring 11 which is rotatably supported by the housing part 1 and can be adjusted relative to the housing 1 , 2 with respect to its angular position. The outer rotor 5 is freely rotatably mounted in the eccentric ring 11 by means of a sliding pivot bearing. The eccentric ring 11 is also stored in the housing 1 , 2 by means of a sliding pivot bearing. An outer lateral surface of the eccentric ring 11 forms a bearing surface 12 for the eccentric ring 11 and an inner lateral surface 13 of the eccentric ring 11 forms a running surface 13 on which the outer rotor 4 runs. The bearing surface 12 is concentric with the axis of rotation 4 ′ of the inner rotor 4 . The tread 13 forms the pivot bearing surface for the outer rotor 5 and is accordingly concentric with its axis of rotation 5 '.

Fig. 1a shows the eccentric ring 11 and the ring gear set 4 , 5 in a starting position in which the specific delivery volume of the pump has its maximum. By rotating the eccentric ring 11 against the pump rotation direction D, the axis of rotation 5 ′ of the outer rotor 5 moves from the position of FIG. 1a against the pump rotation direction D about the axis of rotation 4 ′ of the inner rotor 4 . The maximum adjustment angle of this change in the angular position of the eccentric ring 11 is limited to 90 ° by means of a mechanical stop. FIG. 1b shows the eccentric ring 11 in its end position in which the specific volume of the pump has reached its minimum. The end position shown in FIG. 1b is the zero position of the pump, in which ideally no fluid is delivered. In the zero position, the groove openings on the low-pressure side and the high-pressure side preferably extend symmetrically on both sides of the locations of the deepest and lowest tooth engagement.

Figs. 2 to 4 show an adjusting mechanism for adjusting the angular position of the eccentric ring 11, wherein the basic mode of operation can be seen already from the illustration of Fig. 2 and Figs. 3 and 4 further details.

The eccentric ring 11 is part of a one-piece, preferably sintered, bearing body 10 . The bearing body 10 forms a bearing pot with the eccentric ring 11 as the pot wall and a radial web 14 as the pot bottom. A pin 15 protrudes from the web 14 in the axial direction on the end face facing away from the eccentric ring 11 . The pin 15 is rotationally symmetrical and arranged concentrically to the common axis of rotation 4 'of the eccentric ring 11 and the inner rotor 4 . The pin 15 is provided with external teeth 16 . In the exemplary embodiment, the external toothing 16 is designed as a straight toothing which is embedded in the outer lateral surface of the pin 15 or is subsequently incorporated. In the axial direction on both sides of the toothing 16 , smooth lateral surfaces remain on the pin 15 , which serve as additional bearing surfaces for the bearing body 10 in addition to the bearing surface 12 of the eccentric ring 11 .

The inner rotor 4 could also be rotatably mounted in the journal 15 and could only be carried along by the journal 3 . In the case of such a bearing, the torque of the inner rotor 4 can support the adjustment rotation of the eccentric ring 11 via the pivot bearing. Such support can also be obtained by pivoting the eccentric ring 11 in the journal 15 on the shaft journal 3 .

The pin 15 with the external toothing 16 forms the output member of a gear transmission. The drive member of the gear transmission is formed by a thrust member 21 with teeth 22 . The toothing 22 is provided as a rotationally symmetrical tooth profile on the outer circumference of the thrust member 21 . The thrust member 21 also forms in one piece an actuating piston 20 , on which a pump pressure on the high pressure side acts for adjustment and generates the adjusting force. Although the fluid is preferably branched off directly in the pump housing, the pressure fluid for the actuating piston can in principle only be branched off and returned by a consumer or between the pump and a consumer.

The thrust member 21 is formed by a rotationally symmetrical, hollow cylindrical body which has three functional sections in the axial direction. A front section of this body forms the actuating piston 20 , to which the toothing 22 connects as a central section. A rear section 23 adjoins the toothing 22 at the other end of the thrust member 21 and, like the actuating piston 20, serves as a sliding guide surface and support surface for the central section with the toothing 22 . A plurality of ring webs arranged one behind the other in the axial direction form the teeth of the toothing 22 .

A counterforce to the adjusting force is generated by a spring member 30 , which is designed as a spiral spring and installed as a compression spring. The spring member 30 is inserted into the hollow cylindrical thrust member 21 up to a front end face, the end face simultaneously forming a piston head of the actuating piston 20 .

At the rear, the spring member 30 is supported in the installed state against a closure body 31 , which in the installed state is connected to the housing part 1 so that it cannot move. In the starting position, the spring member 30 is preferably biased.

FIGS. 3 and 4 show the ring gear pump, and in particular the adjusting mechanism in the installed state in a longitudinal section along the axis of rotation 4 '(Fig. 3) and a rectangular cross section (Fig. 4) thereto. The cuts run through the engagement of the two toothings 16 and 22 . The cross-sectional representation of FIG. 4 includes a central longitudinal section through the hollow cylindrical body forming the thrust member 21 and the actuator piston 20. This hollow cylindrical body is received in a circular cylindrical bore 25 in the housing part 1 and is slidably guided in a straight line. The receiving bore 25 in the housing part 1 is a blind bore, at the end of which a fluid connection opens to the high-pressure side of the pump. The mouth is shown in dashed lines in Fig. 4 and designated by reference numeral 27 . The receiving bore 25 closely surrounds the hollow cylindrical body on all sides, in particular in the area of the actuating piston 20 and the further guide section 23 . In the engagement area of the gears 16 and 22, the mounting hole 25 to the pin teeth 16 is open. In a front region of the receiving bore 25 , the housing part 1 forms a cylinder for the actuating piston 20 . The fluid connection to the high-pressure pump side opens into a cylinder pressure chamber 26 formed by the receiving bore 25 , which is delimited in an axial direction by the actuating piston 20 . At its front end, the actuating piston 20 has a nose, with which the actuating piston 20 in the displacement position shown in FIG. 4, which corresponds to the starting position of the eccentric ring 11 of FIG. 1a, due to the spring force of the spring member 30 against the end face of the pressure chamber 26 is pressed. Because of the nose, the pressure chamber 26 also has a minimal volume in the initial position, in which the mouth 27 of the fluid connection is arranged. Between the rear end of the guide section 23 and an abutment end face of the closure body 31 there remains a clear distance which corresponds to the maximum travel of the actuating piston 20 . The starting position and the end position of the actuating piston 20 and the thrust member 21 and thus also the starting position and the end position of the eccentric ring 11 are thus each limited and defined by a mechanical stop. The stop for the starting position forms the end face of the pressure chamber 26 and the stop for the end position forms the closure body 31 .

A control start pressure, at which the actuating movement of the actuating piston 20 begins from the starting position, and a regulating end pressure, at which the actuating piston 20 is fixed at the mechanical stop at 31, are adjusted by coordinating the size of the piston surface and the spring characteristic of the spring member 30 . By adjusting the piston surface and the spring characteristic or, in the case of a predetermined piston surface, by selecting a spring element 30 with a specific spring characteristic, the adjustment characteristic can be adapted within wide limits to the particular application of the pump.

The compact design of the gerotor pump and in particular the compact and robust, since rigid construction of the adjustment gear also appears in FIG. 3. The ring gear set with the inner rotor 4 and the outer rotor 5 is completely received in the bearing cup, which is formed by the eccentric ring 11 and the web 14 , between the web 14 and the opposite housing part 2 and surrounded by the eccentric ring 11 . The bearing cup is very short when viewed in the axial direction because of the preferably exactly radial extension of the web 14 . The thrust member 21 can be arranged so that it does not protrude beyond the eccentric ring 11 or only slightly.

The conversion of the adjusting movement of the actuating piston 20 into the rotary motion of the eccentric ring 11 authoritative pitch circle diameter of the toothing 16 is considerably smaller than the diameter of the bearing surface 12 and also substantially smaller than the smallest distance of the tread 13 of the eccentric ring 11 from the Exzenterringdrehachse 4 '. Between the location of the engagement of the two teeth 16 and 22 , ie the flank contact of the teeth 16 and 22 , and the eccentric ring 11 , in particular the tread 13 of the eccentric ring 11 , the toothed pin 15 and the web 14 form a rocker. In the cam joint formed by the toothings 15 and 16 , an adjustment path of the adjusting piston 20 is first converted into an equally long circumferential path of the pin 15 , this circumferential path being measured along the pitch circle diameter of the toothing 16 . The angle of rotation corresponding to the circumferential path of the pin 15 is transmitted 1: 1 to the eccentric ring 11 by the swivel arm formed by the rockers 14 , 15 . Depending on the length of the swivel arm, even small adjustment paths of the actuating piston 20 cause large adjustment paths of the eccentric ring 11 , measured along the bearing surface 12 and the running surface 13 .

As can be seen in particular in FIG. 3, because of the simple design of the two toothings 16 and 22, a point contact is obtained in the engagement area. Instead, for example, the toothing 16 could be applied to the toothing 22 over part of the circumference of the toothing 22 , in that the toothing 16 runs out correspondingly towards its two axial edges. Although less preferred, in order to achieve line contact, the toothing 22 could be designed as a toothed rack profile which is straight transversely to the axial direction of the thrust member 21 instead of by means of flanges.

Since, due to the invention, the adjustment paths of the actuating piston 20 can be particularly short, on the one hand it is achieved that the linear part of the adjustment gear, essentially the thrust member 21 , can be kept very short. On the other hand, it is advantageous that the spring travel of the spring member 30 is also advantageously short, so that the spring force required for automatic volume control can be generated solely by the spring member 30 . The adjustment mechanism of the invention manages with two parts which move relative to one another and form a single cam joint, namely the bearing body 10 and the body which forms the thrust member 21 and the actuating piston 20 . Finally, in the case of a preferably rotationally symmetrical shape of the cylindrical body 20 , 21 , the receiving bore 25 for this body can also have a simple circular cylindrical design, so that the production of the body 20 , 21 and the receiving bore 25 as well as the assembly in the receiving bore 25 are simple and therefore inexpensive and also expect high operational reliability for the variable speed gear. The piston surface of the actuating piston 20 can also be chosen almost freely, which makes it possible to use spring elements with low spring forces and therefore also particularly compact spring elements.

If the installation space in the pump housing permits it, two toothed thrust members which engage in the toothing 16 at preferably diametrically opposite locations can be provided in order to shorten the adjustment paths of each of these thrust elements in comparison to the adjustment path of such an individual thrust element described using the exemplary embodiment. One of the thrust members can rotate the bearing body 10 over a first angular range and the other thrust member can rotate the bearing body 10 over a subsequent, second angular range. The length of the engagement of the thrust links must be set accordingly.

LIST OF REFERENCE NUMBERS

1

housing part

2

housing part

3

shaft journal

4

inner rotor

4

'' Rotary axis of rotation, eccentric ring axis of rotation

4

a external toothing

5

outer rotor

5

'' Rotary axis

5

i internal toothing

6

-

7

Delivery cells low pressure side

7

'' High pressure side conveyor cells

8th

-

9

-

10

bearing body

11

eccentric

12

storage area

13

tread

14

web

15

spigot

16

gearing

17

-

18

-

19

-

20

Actuator, actuator piston

21

pusher member

22

gearing

23

guide section

24

-

25

location hole

26

pressure chamber

27

muzzle

28

-

29

-

30

Reset link, spring link

31

closure body

Claims (11)

1. Gerotor pump with delivery volume adjustment, the pump comprising:

• a) a housing ( 1 , 2 )
• b) a rotatably mounted outer rotor ( 5 ) which is accommodated by the housing ( 1 , 2 ) and has an internal toothing ( 5 i),
• c) a rotatably mounted inner rotor ( 4 ), which has an external toothing ( 4 a) which meshes with the internal toothing ( 5 i), the internal toothing ( 5 i) having at least one tooth more than the external toothing ( 4 a) and the internal toothing ( 5 i) and the external toothing ( 4 a) form mutually sealed, expanding and compressing conveyor cells ( 7 ),
• d) low-pressure and high-pressure openings arranged laterally in the area of the conveyor cells ( 7 ) in the housing ( 1 , 2 ) and separated from one another by webs,
• e) an eccentric ring ( 11 ) which is rotatably mounted in the housing ( 1 , 2 ) about an eccentric ring axis of rotation ( 4 ') and one of the rotors ( 4 , 5 ) rotatably about a rotor axis of rotation ( 5 '), the rotor axis of rotation ( 5 ') and the eccentric ring axis of rotation ( 4 ') are eccentric to one another,
• f) and an adjusting mechanism coupled with the eccentric ring (11) and converts an adjusting force in a acting on the eccentric ring (11) rotary actuator torque and comprises an actuator (20) in the housing (1, back 2) and reciprocally is recorded and on which the adjusting force acts,

characterized in that

• a) the eccentric ring ( 11 ) is connected to a rocker arm ( 14 , 15 ) rotatably mounted about the eccentric ring axis of rotation ( 4 ')
• b) and the rocker ( 14 , 15 ) forms a swivel arm for the eccentric ring ( 11 ) in the adjustment gear.

2. Gerotor pump according to the preceding claim, characterized in that the adjustment gear ( 14 , 15 , 20 , 21 ) comprises a cam gear ( 15 , 21 ) with at least one cam joint and the rocker ( 14 , 15 ) is an output member of the at least one cam joint , 3. Gerotor pump according to one of the preceding claims, characterized in that a eccentric ring ( 11 ) and a pin ( 15 ) project from an eccentric ring axis of rotation ( 4 '), preferably radial web ( 14 ) and axially opposite directions and the web ( 14 ) and the pin ( 15 ) form the rocker ( 14 , 15 ). 4. Gerotor pump according to one of the two preceding claims, characterized in that the cam mechanism ( 15 , 21 ) with the actuator ( 20 ) connected, preferably non-displaceably connected thrust member ( 21 ) and the pin ( 15 ) and a linear movement of the thrust member ( 21 ) into a rotary movement of the pin ( 15 ) about the eccentric ring axis of rotation ( 4 '). 5. Gerotor pump according to the preceding claim, characterized in that the thrust member ( 21 ) and the pin ( 15 ) engage directly in one another. 6. gerotor pump according to one of the three preceding claims, characterized in that on the actuator ( 20 ) of the adjusting force acts counter to a restoring element ( 30 ) and that the restoring element ( 30 ) and the at least one cam joint in the direction of movement of a thrust element ( 21 ) of the adjusting mechanism are arranged to overlap each other. 7. Gerotor pump according to one of the four preceding claims, characterized in that the cam mechanism ( 15 , 21 ) is a gear mechanism and a thrust member ( 21 ) with a toothing ( 22 ) a drive member and the pin ( 15 ) with a toothing ( 16 ) form an output member of the gear transmission. 8. gerotor pump according to the preceding claim, characterized in that the toothing ( 22 ) of the thrust member ( 21 ) is formed on a lateral surface of a cylindrical body. 9. gerotor pump according to the preceding claim, characterized in that the cylindrical body also forms the actuator ( 20 ). 10. gerotor pump according to one of the preceding claims, characterized in that a hollow cylindrical body forms the thrust member ( 21 ) and is open at one end facing away from the actuator ( 20 ) and that in the cylindrical body a reset member ( 30 ) is received, the exerts a counterforce counteracting the adjusting force on the actuator ( 20 ). 11. Gerotor pump according to one of the preceding claims, characterized in that
a bearing body ( 10 ) has a bearing pot ( 11 , 14 ) and a pin ( 15 ),
a forms a lateral surface of the bearing cup (11, 14) is formed by the eccentric ring (11), the circumferential surface to the rotation axis (4 ') of one of the rotors (4, 5) concentric bearing surface (12) for the bearing body (10),
the pin ( 15 ) protrudes concentrically with respect to the bearing surface ( 12 ) from the bearing pot ( 11 , 14 )
and that the pin ( 15 ) forms an output member of a cam joint of the adjustment gear ( 14 , 15 , 20 , 21 ).