Gerotor Pump

Abstract

SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to improve gerotor pumps from the standpoint of noise emissions. The gerotor pump according to the invention comprises an externally rotatably mounted gerotor, said gerotor having at least one tooth with a cavity, said gerotor being closed by a side plate and / or a cap, said cavity having a fluid connection radially inwards. Preferably, a number of teeth of the gerotor, particularly preferably all teeth, are designed accordingly. The fluid connection allows the interior of the tooth to be used as a hydraulic volume. In other words, a conveying medium, e.g. oil, can flow in at the right time therein to damp pulsations which are the cause of undesirable noise.

Description

[Technical field]

[0001] The present invention relates to gerotor pumps, and more particularly to gerotor pumps with improved noise emissions. [Background technology]

[0002] Gerotor pumps are widely used in the automotive industry, particularly as oil pumps and cooling pumps. The provision of a vane pump having an intermediate hydraulic capacity is known from US Pat. No. 5,399,636. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE 10027990 A1 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to improve gerotor pumps from the standpoint of noise emissions. That object is achieved by the subject matter of claim 1. [Means for solving the problem]

[0005] Thereby, the gerotor pump according to the invention comprises an externally rotatably mounted gerotor, said gerotor having at least one tooth with a cavity, said gerotor being closed by a side plate and / or a cap, said cavity having a fluid connection radially inwards. Preferably, a number of teeth of the gerotor, particularly preferably all teeth, are designed accordingly. The fluid connection allows the interior of the tooth to be used as a hydraulic volume. In other words, a conveying medium, for example oil, can flow in at the right time therein and damp pulsations which are the cause of undesirable noise.

[0006] Such pulsations occur, for example, when a fluid-filled cell separated by the teeth in question moves from the suction side to the pressure side between the outer and inner gerotors. During this "change of motion," the cell in question is connected to pressurized fluid, which results in a pressure surge and can cause undesirable noise. In accordance with the present invention, this pressure surge can be dampened and / or mitigated by fluidly connecting fluid to the tine cavities, thus fluidly connecting the damping volumes of the rotor tines to the cell during an operational change, i.e., when the cell switches from tank pressure to outlet pressure between the outer gerotor and the inner rotor. Preferred further developments of the invention are set out in the remaining claims.

[0007] With regard to the specific design of the fluid connections, cutouts, slots, openings, or bores work well. A bore typically runs straight and has a cylindrical cross section. An opening can have any cross section and can run straight or with one or more curves and / or bends. The slots or cutouts can be provided at the axial ends of the gerotor, as described in more detail below.

[0008] The fluid connections can extend substantially in the radial direction of the gerotor, such that they are connected to both the suction side and the pressure side at a certain point in time. However, improved properties are expected if the fluid connections extend at least partially outside the center of the tooth and / or at an angle to the radial direction, in particular inclined to the direction of rotation when viewed radially from the outside. The aforementioned angle and / or inclination is substantially related to the central axis of the fluid connection, in particular at its radially inner end, although only the opening of the fluid connection at the radially inner end may be formed inclined to the radial direction. In other words, the fluid connections can be aligned differently from the radially inner side, as described above, in particular in the radially outer region.

[0009] Thus, in this advantageous embodiment, two attenuation volumes can be connected in a cell exchange operation. Preferably, for rotors with five teeth and outer rotors with six teeth, the inclination angle is between 5 and 15 degrees. For rotors with more or fewer teeth, this angle will vary accordingly. The invention is particularly well suited to implementation with plastic gerotors, since in this case the tooth or teeth can be easily formed in the cavity. Furthermore, the described fluid connection can be provided at minimal expense, for example, during casting of the gerotor. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a main part of a gerotor pump according to the present invention in a first embodiment. [Diagram 2] FIG. 4 is a cross-sectional view through the main parts of a gerotor pump according to the present invention in a second embodiment. [Diagram 3] FIG. 1 is a plan view of a gerotor of a gerotor pump according to the present invention in a first embodiment. [Figure 4] FIG. 11 is a plan view showing a gerotor of a gerotor pump according to the present invention in accordance with a second embodiment. [Diagram 5] FIG. 5 shows substantially a detail according to FIG. 4, with the inner rotor and the flows indicated. [Figure 6] FIG. 13 is a top view of a gerotor similar to the second embodiment with an inner rotor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings. As can be seen from Figures 1 and 2, the gerotor 12 of the pump according to the invention has teeth 22 (see also Figures 3 and 4) with cavities 18. In the illustrated case, these are axially closed by side plates 14 with fluid passages 16. However, cavities 18 can alternatively or additionally be closed by caps (not shown). For technical manufacturing reasons, cavities 18 can be designed to widen axially towards their axial opening.

[0012] In FIG. 1, 20 indicates a radially inner fluid connection according to the invention, in this case 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 cutout or slot. In other words, the radially inner boundary wall is designed to be locally shortened. In both cases, the diameter of the fluid connection 20 can be the area of ​​the wall thickness of the inner or outer boundary wall of the tooth 22 or can deviate therefrom, for example by ±20%. In addition, it should be noted that gerotor 12, viewed in cross section, is designed to be substantially U-shaped or pan-shaped, with an undulating radially inner boundary wall for forming teeth 22, as seen in plan view in Figures 3 and 4. This has the advantage of cost-effective manufacture. However, it is also possible for the gerotor itself to be open on both axial sides. In the example shown, both the radially outer and inner boundary walls have a substantially uniform thickness and the cavity is in the shape of a circular segment, which facilitates manufacture by casting from plastic.

[0013] In the embodiment example of FIG. 3, the fluid connection 20 extends in the form of a bore substantially in the radial direction, but according to FIG. 4 is arranged inclined in the direction of rotation at an angle α of, for example, 20 to 40 degrees. 5, how gerotor 12, as described and shown above, interacts with inner rotor 24 such that fluid is conveyed through tooth 22 into cavity 18, indicated at A, which forms a sort of balance volume for damping pressure pulsations in accordance with the present invention.

[0014] Figure 6 shows a similar design to figure 4 with an inner rotor 24, in which in particular the cell 26 under tank pressure / suction pressure, the changing behaviour of the cell 28 and the cell 30 under outlet pressure can be seen. Based on the changing behaviour of the cell 28, it can be seen that in the illustrated design, the two cavities 18 are connected to the cell 28 as damping volumes. As shown, fluid connection 20 is not only angled radially outwardly, but is also rotationally tilted with respect to its central axis and is located off-center, i.e., the connection of cells 28 and teeth 22 to cavities 18 is not at the highest point of teeth 22. However, the central axis may intersect the circumference of gerotor 12 at a point corresponding to the highest point of teeth 22. [Explanation of symbols]

[0015] 12 Gerota 14 Side Plate 16 Fluid passage 18 Cavity 20 Fluid connection 22 teeth 24 Inner rotor 26, 28, 30 cells

Claims

1. an externally rotatably mounted gerotor (12), said gerotor (12) having at least one tooth (22) with a cavity (18); The gerotor (12) is closed by a side plate (14) and / or a cap; A gerotor pump, characterized in that the cavity (18) has a radially inner fluid connection (20).

2. 2. The gerotor pump of claim 1, wherein the fluid connection (20) is formed as a cutout, a slot, an opening or a bore.

3. 3. The gerotor pump of claim 1 or 2, wherein the fluid connection (20) extends at least partially radially of the gerotor (12) and / or externally intermediate the teeth (22).

4. 4. The gerotor pump according to claim 3, wherein the fluid connection portion (20) is inclined in the direction of rotation when viewed radially from the outside to the inside.

5. 5. The gerotor pump of claim 4, wherein the angle of inclination is between 5 and 15 degrees.

6. 2. The gerotor pump of claim 1, wherein the gerotor (12) is made of plastic.

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