GEROTOR PUMP

Abstract

A gerotor pump has an outer, rotatably mounted gerotor having at least one hollow tooth which is closed by a lateral plate and/or a cap, the interior of which has a fluid connection radially inwards. The fluid connection may be formed as a cut-out, slot, opening or bore. Further, the fluid connection may extend at an angle to a radial direction of the outer gerotor and/or outside of the middle of the tooth at least in part.

Description

TECHNICAL FIELD

The invention relates to a gerotor pump.

PRIOR ART

Gerotor pumps are used extensively in the automotive sector in particular, for example as oil pumps and coolant pumps.

BACKGROUND

Providing a vane pump with hydraulic intermediate capacities is known from DE 100 27 990 A1.

DESCRIPTION OF THE INVENTION

The invention is based on the object of improving a gerotor pump in terms of noise emissions.

The object is achieved by the subject matter as shown and described herein.

According thereto, the gerotor pump according to the invention has an outer, rotatably mounted gerotor having at least one hollow tooth, which is closed by a lateral plate and/or a cap, the interior of which has a fluid connection radially inwards. Preferably, a plurality of the teeth, and particularly preferably all of the teeth, of the gerotor are designed accordingly. The fluid connection allows the interior of the tooth to be used as hydraulic capacity. In other words, the medium to be conveyed, like oil, for example, can flow into the interior at the appropriate time, such that pulsations that are responsible for undesirable noise emissions can be damped.

Such pulsations occur when, for example, a certain fluid-filled cell, which is delimited by the tooth in question, moves between the outer and inner gerotor from the suction side to the pressure side. During this “operation change”, the cell under consideration is connected to pressurised fluid, which results in a pressure surge that can cause undesirable noise.

According to the invention, this pressure surge can be damped and/or lessened by allowing fluid to enter the hollow tooth by way of the fluid connection described. This therefore advantageously allows the damping volume in the rotor tooth to be hydraulically connected to the cell at the time of the operation change, i.e. at the time at which this cell switches between the outer gerotor and inner rotor from tank pressure to outlet pressure.

With regard to the specific design of the fluid connection, good results are expected for a cut-out, slot, opening or bore. A bore typically extends in a straight line and with a cylindrical cross section. An opening can have any cross section and can extend in a straight line or with one or more curves and/or bends. A slot or cut-out can, as will be described in more detail in the following, be provided at an axial end of the gerotor.

The fluid connection can extend substantially in the radial direction of the gerotor, such that at a particular point in time it is connected to both the suction side and the pressure side. However, improved properties are expected when the fluid connection extends, at least in part, outside of the middle of the tooth and/or at an angle to the radial direction and in particular inclined in the direction of rotation when viewed radially from the outside in. The aforementioned angle and/or inclination substantially relates to the central axis of the fluid connection in particular at the radially inner end thereof; however, it may be that only the opening of the fluid connection at the radially inner end is formed at an angle with respect to the radial direction. In other words, the fluid connection can, particularly in radially outer regions, be aligned differently from radially inward, as described above.

This advantageous embodiment therefore allows two damping volumes to be connected to the cell changing operation.

This preferably results in an angle of inclination of 5-15° in the case of a rotor having five teeth and an outer gerotor having six teeth. In the case of rotors having more or fewer teeth, this angle changes accordingly.

The invention can be implemented particularly well in the case of a gerotor made of plastic since in this case one or more teeth can easily be formed so as to be hollow. Furthermore, the fluid connection described can be provided with minimal outlay, as early as during the casting of the gerotor, for example.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, preferred embodiment examples of the invention will be described in more detail with reference to the figures. In the drawings:

FIG. 1 shows a cross section through significant parts of a gerotor pump according to the invention in a first embodiment;

FIG. 2 shows a cross section through significant parts of a gerotor pump according to the invention in a second embodiment;

FIG. 3 shows a plan view of a gerotor of the gerotor pump according to the invention in a first embodiment;

FIG. 4 shows a plan view of a gerotor of the gerotor pump according to the invention in a second embodiment;

FIG. 5 substantially shows the detail according to FIG. 4 with the inner rotor and indicated flow; and

FIG. 6 shows a plan view of the gerotor similar to the second embodiment, with inner rotor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

As can be seen from FIGS. 1 and 2, an outer gerotor 12 of the pump according to the invention has teeth 22 (cf. also FIGS. 3 and 4) having cavities 18. In the case shown, these are axially closed by way of a lateral plate 14 having fluid passages 16. However, the cavities 18 can alternatively or additionally be closed by way of caps (not shown). For manufacturing-related technical reasons, the cavities 18 can be designed so as to widen in the axial direction towards the axial opening thereof.

In FIG. 1, 20 indicates the fluid connection radially inwards as according to the invention, which in this case is formed as an opening or bore in the radially inner boundary wall of the tooth 22.

According to FIG. 2, the fluid connection 20 is designed as a cut-out or slot. In other words, the radially inner boundary wall is designed so as to be shorter locally. In both cases, the diameter of the fluid connection 20 can be in the region of the wall thickness of the inner or outer boundary wall of the tooth 22, or it can deviate therefrom by up to +/−20%, for example.

In addition, it is noted that the gerotor 12, seen in cross section, is designed so as to be substantially U-shaped or pot-shaped, and, as can be seen in FIGS. 3 and 4, in plan view the radially inner boundary wall for forming the teeth 22 extends in a wave-like manner. This is advantageous for cost-effective manufacturing. The gerotor itself could be open on both axial sides, however.

In the examples shown, both the radially outer and the radially inner boundary wall have a substantially uniform thickness, and the cavities are in the shape of a circular segment. This facilitates manufacturing by casting from plastic.

In the embodiment example of FIG. 3, the fluid connection 20 extends in the form of a bore substantially in the radial direction, while according to FIG. 4 it is aligned so as to be inclined at an angle a of, for example, 20-40 degrees in the direction of rotation.

Moreover, it is clear from FIG. 5 how the outer gerotor 12 as described and shown above interacts with an inner rotor 24 such that fluid can be conveyed. The flow into the cavity 18 of a tooth 22 is indicated by A, and the cavity 18 forms a sort of balancing volume in order to damp pressure pulsations according to the invention.

FIG. 6 shows a design similar to FIG. 4 with the inner rotor 24 such that in particular a cell 26 under tank pressure/suction pressure, a cell 28 changing operation and a cell 30 under outlet pressure can be seen. On the basis of the cell 28 changing operation, it can be seen in the design shown that two cavities 18 are connected to the cell 28 as damping volumes.

In the case shown, the fluid connection 20 is inclined in the direction of rotation with respect to its central axis, not just when viewed from radially outside in; it is also arranged off-centre, i.e. the connection to the cell 28 and to the cavity 18 of the tooth 22 is not at the highest point of the tooth 22. The central axis can, however, intersect the outer circumference of the gerotor 12 at a point corresponding to the highest point of the tooth 22.

Claims

1-6. (canceled)

7. A gerotor pump comprising: an outer, rotatably mounted gerotor having at least one hollow tooth which is closed by a lateral plate and/or a cap, an interior of the tooth has a fluid connection radially inwards.

8. The gerotor pump according to claim 7, wherein the fluid connection is formed as a cut-out, slot, opening or bore.

9. The gerotor pump according to claim 7, wherein the fluid connection extends at an angle to a radial direction of the outer gerotor and/or outside of a middle of the tooth at least in part.

10. The gerotor pump according to claim 9, wherein the fluid connection is inclined in a direction of rotation when viewed radially from the outside in.

11. The gerotor pump according to claim 10, wherein an angle of inclination is between 5 and 15 degrees.

12. The gerotor pump according to claim 7, wherein the outer gerotor is made of plastic.