Fluid delivery device with a forepump, a main pump, and bypass line with a check valve

Abstract

A fluid delivery device having a forepump and a main pump fluidically connected to the forepump, wherein the forepump can be driven via a forepump input shaft and the main pump can be driven via a main pump input shaft. According to the invention, the forepump has a forepump drive gear coupled to the forepump input shaft and a forepump delivery gear interacting with the forepump drive gear to deliver the fluid, wherein the forepump and the main pump are drivingly coupled to a common drive shaft, and wherein the forepump delivery gear and the main pump input shaft are connected to one another via a connecting shaft such that the forepump input shaft is coupled directly to the drive shaft and the main pump input shaft is coupled to the drive shaft via the connecting shaft.

Claims

1. A fluid delivery device having: a forepump and a main pump fluidically connected to the forepump, wherein the forepump is driven via a forepump input shaft and the main pump is driven via a main pump input shaft, wherein the forepump has a forepump fluid inlet and a forepump fluid outlet; the main pump has a main pump fluid inlet and a main pump fluid outlet, wherein a delivery device fluid inlet of the fluid delivery device is fluidically connected to the forepump fluid inlet, the forepump fluid outlet is fluidically connected to the main pump fluid inlet, and the main pump fluid outlet is fluidically connected to the delivery device fluid outlet of the fluid delivery device, wherein the forepump has a forepump drive gear coupled to the forepump input shaft and a forepump delivery gear interacting with the forepump drive gear to deliver the fluid, wherein the forepump and the main pump are drivingly coupled to a common drive shaft, and wherein the forepump delivery gear and the main pump input shaft are connected to one another via a connecting shaft such that the forepump input shaft is coupled directly to the drive shaft and the main pump input shaft is coupled to the drive shaft via the connecting shaft, wherein the forepump fluid outlet is fluidically connected to the forepump fluid inlet via a bypass line having a check valve, and the forepump has a larger delivery volume than the main pump.

2. The fluid delivery device according to claim 1, wherein the forepump drive gear and the forepump delivery gear form a transmission gear for the main pump having a specific transmission ratio.

3. The fluid delivery device according to claim 1, wherein the forepump is a gear pump and/or the main pump is designed as a rotary piston pump.

4. The fluid delivery device according to claim 1, wherein the main pump has a main pump drive gear and a main pump delivery gear interacting with the main pump drive gear to deliver the fluid, wherein the forepump delivery gear and the main pump drive gear are drivingly connected to the connecting shaft.

5. The fluid delivery device according to claim 1, wherein the main pump is an internal gear pump, wherein the main pump drive gear is a pinion gear and the main pump delivery gear is a ring gear.

6. The fluid delivery device according to claim 1, wherein a further transmission gear is arranged in the operative connection between the forepump delivery gear and the main pump input shaft.

7. The fluid delivery device according to claim 1, wherein the forepump and the main pump are arranged in a common pump housing.

8. The fluid delivery device according to claim 1, wherein the main pump is a sickle pump.

Description

(1) The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without the invention being restricted. In the drawings:

(2) FIG. 1 is a schematic illustration of a fluid delivery device having a forepump and a main pump,

(3) FIG. 2 is a schematic illustration of the fluid delivery device in a second view, and

(4) FIG. 3 is a schematic sectional view through the fluid delivery device, wherein the forepump and the main pump are present in a common pump housing.

(5) FIG. 1 shows a schematic illustration of a fluid delivery device 1 which has a forepump 2 and a main pump 3. The forepump 2 has a forepump fluid inlet 4, which is fluidically connected to a delivery device fluid inlet 5. A forepump fluid outlet 6 of the forepump 2 is fluidically connected to a main pump fluid inlet 7. A main pump fluid outlet 8 of the main pump 3 is in turn fluidically connected to a delivery device fluid outlet 9 of the fluid delivery device 1. In the end, the forepump 2 and the main pump 3 are fluidically connected in series between the delivery device fluid inlet 5 and the delivery device fluid outlet 9. It can be seen that the forepump fluid outlet 6 and the forepump fluid inlet 4 are fluidically connected to one another via a bypass line 10. A valve arrangement 11 is provided in the bypass line 10, which has a check valve 12 or is designed as such.

(6) The forepump 2 can be driven via a forepump input shaft 13 and the main pump 3 via a main pump input shaft 14. The forepump 2 and the main pump 3 are drivingly connected to a common drive shaft 15. In other words, the forepump input shaft 13 and the main pump input shaft 14 are both drivingly connected to the drive shaft 15. In the case of the forepump input shaft 13, there is a direct connection. For example, the forepump input shaft 13 is formed in one piece with the drive shaft 15. The main pump input shaft 14, on the other hand, is drivingly connected to the drive shaft 15 via the forepump 2. For this purpose, a forepump drive gear 16 and a forepump delivery gear 17 of the forepump 2 form a transmission gear 18 for the main pump 3.

(7) The forepump drive gear 16 is coupled to the forepump input shaft 13, preferably it sits on it and is connected to it in a fixed and/or permanent manner. The forepump delivery gear 17, on the other hand, is driven by the forepump drive gear 16 during operation of the fluid delivery device 1, that is to say when the drive shaft 15 rotates. In the exemplary embodiment shown here, the forepump 2 is in the form of a gear pump, namely an external gear pump. The forepump drive gear 16 and the forepump delivery gear 17 are in this respect in the form of gears which mesh with one another to form the transmission gear 18. In addition, the forepump drive gear 16 and the forepump delivery gear 17 cooperate to deliver the fluid.

(8) Analogously to this, the main pump 3 has a main pump drive gear 19 and a main pump delivery gear 20. These also work together to provide a fluid delivery effect of the main pump 3. To drivingly connect the main pump 3 to the forepump 2, a connecting shaft 21 is provided which connects the forepump delivery gear 17 and the main pump input shaft 14 and thus the main pump drive gear 19 to one another. In this respect, it is clear that the forepump input shaft 13 is coupled directly to the drive shaft 15, whereas the main pump input shaft 14 is only indirectly drivingly coupled to the drive shaft 15 via the connecting shaft 21 and the forepump 2, i.e. is driven by the drive shaft 15 via the forepump 2.

(9) An embodiment of the fluid delivery device 1 is particularly advantageous, in which both the forepump 2 and the main pump 3 are designed as gear pumps. In the embodiment shown here, the forepump 2 is in the form of an external gear pump and the main pump 3 is in the form of an internal gear pump. Here, the main pump drive gear 19 is a pinion gear 22 and the main pump delivery gear 20 is a ring gear 23 of the internal gear pump. The pinion gear 22 and the ring gear 23 are rotatably mounted about mutually offset axes of rotation. When viewed in cross section, the pinion gear 22 has outer dimensions that are smaller than inner dimensions of the ring gear 23, so that only part of a toothing of the pinion gear 22 meshes with the toothing of the ring gear 23. The internal gear pump is designed as a sickle pump, so that a sickle-shaped filler piece 24 is arranged in regions between the pinion gear 22 and the ring gear 23. Either the forepump 2 or the main pump 3 are preferably designed to be gap-compensated. In particular, an embodiment is preferred in which the main pump 3, but not the forepump 2, is gap-compensated. The forepump 2 is so far without gap compensation. However, both the forepump 2 and the main pump 3 can also be gap-compensated.

(10) FIG. 2 shows a further schematic illustration of the fluid delivery device 1. It can be seen that the forepump 2 or the forepump drive gear 16 and the forepump delivery gear 17 each have helical teeth. As a result, the smooth running of the forepump 2 is significantly improved. With regard to the further configuration of the fluid delivery device 1, reference is made to the above statements.

(11) FIG. 3 shows a further schematic illustration of the fluid delivery device 1. Again, reference is made in full to the above statements. In addition, it is now clear that the forepump 2 and the main pump 3 are arranged in a common pump housing 25. Here, the forepump drive gear 16, the forepump delivery gear 17, the main pump drive gear 19 and the main pump delivery gear 20 are preferably rotatably mounted in and/or on the pump housing 25. A direction of flow of the fluid through the fluid delivery device 1 is indicated by the arrows 26.

(12) The fluid delivery device 1 shown here has excellent delivery properties for the fluid with a long service life because the forepump 2 and the main pump 3 are ideally matched to one another, namely by means of the transmission gear 18.

(13) As shown in FIG. 1, a further transmission gear 28 may be arranged in operative connection between the forepump delivery gear 17 and the main pump input shaft 14.