Gear pump
Supporting the drive shaft on both axial sides of the pumping gear with bearing units and seals addresses the issue of excessive wear in gear pumps, enhancing durability and efficiency in non-lubricating media applications.
Patent Information
- Application Number
- JP2025187882
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-07
- Filing Date
- 2025-11-06
- Publication Date
- 2026-02-03
AI Technical Summary
Gear pumps used for non-lubricating media, such as fuel, experience excessive wear in the region where the pumping gear supported on the drive shaft contacts the pump housing due to lateral loads from high pressure during operation.
The drive shaft is supported on both axial sides of the pumping gear with bearing units, ensuring reliable support against lateral displacement, using a combination of rolling element bearings and shaft seals to prevent contact with the pump housing, and optionally a plain bearing bushing made of polymer or composite material for non-lubricated environments.
This design significantly extends the operating life of the gear pump by preventing excessive wear on the pumping gear, particularly in non-lubricating fuel applications, without the need for additional support structures or lubricants, thus maintaining efficiency and reducing manufacturing costs.
Smart Images
Figure 2026016779000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a gear pump that can be used, for example, to pump liquid fuel in a fuel-operated heating device that can be operated stationary, for example, as a building heater, or that can be used, for example, as an auxiliary heater or parking heater in a vehicle, for example, to heat air to be introduced into the vehicle interior. [Background technology]
[0002] Such gear pumps generally have two gears arranged in mesh with each other in a pumping chamber. One of the gears is supported on a drive shaft that can be rotated by a drive unit, for example, an electric motor, to drive the two gears in rotation and thereby pump the liquid medium present in the pumping chamber. The drive shaft, which is arranged in a pump housing that also provides the pumping chamber, is rotatably supported relative to the pump housing in the axial region between the drive unit and the pumping gear that is connected to rotate with the drive shaft. Summary of the Invention [Problem to be solved by the invention]
[0003] The object of the present invention is to design such a gear pump in such a way that, when pumping a non-lubricating medium, such as a non-lubricating fuel, excessive wear is avoided, particularly in the region of the pumping gear supported on the drive shaft. [Means for solving the problem]
[0004] The object of the present invention is to provide a gear pump for pumping liquid fuel, in particular in fuel-operated heating systems, which comprises: a pumping chamber in a pump housing; a housing cover at least partially closing the pumping chamber; a pumping gear rotatable about its axis of rotation within the pumping chamber; a drive shaft coupled to the pressure gear so as to rotate therewith about a rotation axis; a first bearing unit that supports the drive shaft on the first axial side of the pressure gear; a second bearing unit that supports the drive shaft on the second axial side of the pressure gear; This problem is solved by a gear pump.
[0005] By supporting the drive shaft on both axial sides of the pumping gear connected thereto for rotation, lateral loads on the drive shaft, which are induced in particular by the relatively high pressure of the pumped liquid medium occurring during pumping operation, and which could lead to the pumping gear moving transversely to the rotation axis coming into contact with the wall of the pump housing that defines the pumping chamber, can be avoided, thereby avoiding excessive wear of the pumping gear, particularly in the region of its teeth.
[0006] The drive shaft may be supported relative to the pump housing via a first bearing unit, and the drive shaft may be supported relative to the housing cover via a second bearing unit.
[0007] In order to achieve a design that is as simple and inexpensive as possible, the drive shaft does not need to be supported between the first and second bearing units. Support at only two bearing locations on either side of the drive gear in the axial direction ensures reliable support of the drive shaft, and thus the pressure gear, against lateral displacement movements.
[0008] In this case, in order to avoid such lateral displacement movements in the area of the pressure gear, it is particularly advantageous if the axial distance of the second bearing unit from the pressure gear is smaller than the axial distance of the first bearing unit from the pressure gear.
[0009] To ensure a long operating life, it is proposed that the first bearing unit comprises a first rolling element bearing, which may for example comprise a ball bearing.
[0010] In order to shield this rolling element bearing from the liquid medium to be pumped, it is proposed that the first bearing unit has a first shaft seal, e.g., a shaft seal ring, axially between the first rolling element bearing and the pumping gear, which provides a fluid-tight connection of the drive shaft to the pump housing.
[0011] The second bearing unit may include a second rolling element bearing, for example a ball bearing.
[0012] In order to shield this rolling element bearing from the liquid medium to be pumped, it is proposed that the second bearing unit has a second shaft seal, such as a shaft seal ring, axially between the second rolling element bearing and the pumping gear, which provides a fluid-tight connection of the drive shaft to the housing cover.
[0013] In one alternative configuration, which is particularly advantageous with regard to the required construction space and manufacturing costs, the second bearing unit may have a plain bearing bushing.
[0014] The plain bearing bushing may be made of a polymeric or composite material, i.e. a material that is particularly suitable for using such a plain bearing bushing in a non-lubricated or completely dry environment.
[0015] The invention further relates to a fuel-operated vehicle heating system having a burner region to which combustion air is supplied via a fan and liquid fuel is supplied via a gear pump formed according to the invention, the burner region preferably having an atomizing burner in which a mixture of fuel and combustion air is produced by injection of fuel through atomizing nozzles.
[0016] The present invention will now be described in detail with reference to the accompanying drawings. [Brief explanation of the drawings]
[0017] [Figure 1]FIG. 2 is a partial cross-sectional view of a gear pump. [Figure 2] FIG. 2 is a view corresponding to FIG. 1, showing an alternative configuration. [Figure 3] 1 is a principle diagram of a fuel-operated vehicle heating device. DETAILED DESCRIPTION OF THE INVENTION
[0018] Before the gear pump configuration is described in detail below with reference to Figures 1 and 2, the basic configuration of a fuel-operated vehicle heating system, generally designated 10, will be described with reference to Figure 3. In this vehicle heating system, such a gear pump 12 can be used to pump liquid fuel as a liquid medium.
[0019] The vehicle heating device 10 has a burner region 14 and a heat exchanger region 16. Combustion air L is supplied to the burner region 14 via a combustion air fan 17. Liquid fuel B is also supplied to the burner region 14 via a gear pump 12 and is sprayed by a spray nozzle to form a fuel / combustion air mixture. In a combustion chamber 18 of the burner region 14, the combustion air L is mixed with vaporized fuel B, for example, via a porous vaporization medium, resulting in a combustible mixture of the combustion air L and the fuel B. The combustion exhaust A generated during the combustion flows into the heat exchanger region 16 before being released into the environment. In the heat exchanger region 16, the heat carried in the combustion exhaust A is transferred to a heated medium M. The heated medium M can be, for example, air to be introduced into the vehicle interior. However, the medium M can also basically be a liquid medium, such as a liquid cooling medium present in the cooling medium circuit of a vehicle's internal combustion engine.
[0020] The gear pump 12 has a pump housing generally designated 20. A pumping gear 24 formed as a spur gear is arranged on one side of the pump housing in a pumping chamber generally designated 22. The pumping gear 24 is fixedly supported on a drive shaft 26 extending substantially inside the pump housing 20, so that when the drive shaft 26 is rotated by a drive device (not shown in FIG. 2 ), for example an electric motor, the drive shaft 26 and the pumping gear 24 rotate together about a rotation axis D.
[0021] 1 is also arranged in the pumping chamber 22, like the pumping gear 24, and is located adjacent to the pumping gear 24 laterally with respect to the rotation axis D so that the other pumping gear meshes with the pumping gear 24. Thus, when the pumping gear 24 rotates about the rotation axis D, the other pumping gear, not visible in FIG. 1, is also rotated, so that the liquid medium to be pumped that is present in the pumping chamber 22 is displaced from the pumping chamber 22 and thus discharged towards the system region to be supplied, i.e., for example, the combustion chamber 18.
[0022] In its extension region located inside the pump housing 20, the drive shaft 26 is supported via a first bearing unit 28. The first bearing unit 28 is arranged in a radially expanded region 30 of the pump housing 20, in a shaft opening 32 that receives the drive shaft 26. The first bearing unit 28 has a first rolling element bearing 34, for example formed as a ball bearing, that radially supports the drive shaft 26 relative to the pump housing 20 so that it can rotate. To shield the first rolling element bearing 34 from the medium to be pumped and in particular to prevent the medium from escaping through the shaft opening 32, the first bearing unit 28 has a shaft seal 36, for example formed as a shaft sealing ring, axially between the delivery gear 24 and the first rolling element bearing 34. This shaft seal 36 abuts against both the outer surface of the drive shaft 26 and the inner surface of the radially expanded region 30 of the shaft opening 32, thus realizing a fluid-tight connection of the drive shaft 26, which can rotate around the rotation axis D, to the pump housing 20.
[0023] A housing cover 40 is arranged on the end face 38 of the pump housing 20, which is essentially also open to the pumping chamber 22, and is firmly connected to the pump housing 20, so that the pumping chamber 22 is closed by the housing cover 40 in the direction of the rotation axis D.
[0024] The drive shaft 26 extends axially beyond the pressure gear 24 into a recess 42 formed in the housing cover 40. In this recess 42, the drive shaft 26 is rotatably supported relative to the housing cover 40 via a second bearing unit 44. In the embodiment shown in FIG. 1 , the second bearing unit 44 includes a plain bearing bush 46. The plain bearing bush 46 is made of a material suitable for use in non-lubricated or dry-running environments. For example, the plain bearing bush 46 may be made of or coated with a polymer material at least in its surface region that radially supports the drive shaft 26. It is also possible to use a composite material at least in the surface region that radially supports the drive shaft 26. Such a composite material may include, for example, a carrier body or layer in which solid lubricant particles are embedded. The carrier material may be, for example, lead or copper, and the solid lubricant particles embedded in the carrier material may be made of a PTFE material. Such plain bearing bushes, which are particularly suitable for use with gear pumps, are sold, for example, by GGB Heilbronn GmbH under the trademark or name DU Bush. In this case, the plain bearing bushes are formed with a base body made of steel material, to which a porous sintered bronze intermediate layer is applied, which is in turn coated on the supporting side with a sliding layer mixture made of PTFE and lead.
[0025] By supporting the drive shaft 26 on both axial sides of the pump gear 24, and in particular by positioning the second bearing unit 44 axially much closer to the pump gear 24 than the first bearing unit 28, lateral displacement movements of the drive shaft 26 and thus the pump gear 24 are virtually completely eliminated in the axial region where the pump gear 24 is supported on the drive shaft 26. This means that the risk of the pump gear 24 striking with its teeth in the radially outer region, enclosed by line I in FIG. 1, against the wall of the pump housing 20 that defines the pumping chamber 22, which would result in excessive wear of the pump gear 24, is eliminated. This makes the gear pump 12 particularly suitable for use with non-lubricating media or fuels, such as kerosene, gasoline, etc., and therefore the addition of lubricant additives can be dispensed with. By supporting the drive shaft 26 by the two bearing units 28, 44 on both axial sides of the pressure gear 24, additional support means, such as a separate bearing unit between the first bearing unit 28 and the pressure gear 24 and / or a separate bearing unit between the first bearing unit 28 and the drive device (not shown), can be omitted.
[0026] An alternative embodiment of such a gear pump 12, particularly for use with non-lubricating pumped media, is shown in Figure 2. In the embodiment shown in Figure 2, a second bearing unit 44 is formed with a second rolling element bearing 48, by means of which the drive shaft 26 is radially supported in the housing cover 40. Axially, between the second rolling element bearing 48, which is also formed as a ball bearing, for example, and the pumping gear 24, a second shaft seal 50, for example also in the form of a shaft sealing ring, is arranged to shield the second rolling element bearing 48 from the pumped media.
[0027] Again, this configuration substantially completely eliminates lateral displacement of the pressure gear 24, thereby eliminating excessive wear, particularly in the region of the radially outer teeth of the pressure gear 24.
[0028] The gear pump formed according to the present invention can significantly extend the operating life of such a gear pump, particularly when the gear pump is used, for example, in a fuel-operated vehicle heating system, together with a non-lubricating or poorly lubricating fuel to pump this fuel into a combustion chamber, by avoiding non-lubricating contact between the pumping gear supported on the drive shaft and the wall surrounding the pumping chamber, without requiring relatively complex structural measures or radial intermediate spaces between the teeth of the pumping gear and the wall of the pump housing surrounding the pumping chamber, which would hinder pumping efficiency.
Claims
1. A gear pump for pumping liquid fuel, in particular in a fuel-operated heating device, comprising: a pumping chamber (22) in the pump housing (20); a housing cover (40) at least partially closing said pumping chamber (22); a pumping gear (24) rotatable about its axis of rotation (D) in said pumping chamber (22); a drive shaft (26) connected to said pressure gear (24) for co-rotation about said axis of rotation (D); a first bearing unit (28) supporting said drive shaft (26) on a first axial side of said pressure gear (24); a second bearing unit (44) supporting the drive shaft (26) on a second axial side of the pressure gear (24); Including, gear pump.
2. 2. The gear pump according to claim 1, wherein the drive shaft (26) is supported relative to the pump housing (20) via the first bearing unit (28) and / or the drive shaft (26) is supported relative to the housing cover (40) via the second bearing unit (44).
3. 3. The gear pump according to claim 1, wherein the drive shaft (26) is not supported between the first bearing unit (28) and the second bearing unit (44).
4. 4. The gear pump according to claim 1, wherein the axial distance of the second bearing unit (44) from the pressure gear (24) is smaller than the axial distance of the first bearing unit (28) from the pressure gear (24).
5. 5. Gear pump according to claim 1, wherein the first bearing unit (28) comprises a first rolling element bearing (34).
6. The gear pump of claim 5, wherein the first rolling element bearing (34) comprises a ball bearing.
7. 7. A gear pump according to claim 5 or 6, wherein the first bearing unit (28) has a first shaft seal (36) axially between the first rolling element bearing (34) and the compression gear (24) to provide a fluid-tight connection of the drive shaft (26) to the pump housing (20).
8. Gear pump according to any one of the preceding claims, characterized in that the second bearing unit (44) comprises a second rolling element bearing (48).
9. The gear pump of claim 8, wherein the second rolling element bearing (48) comprises a ball bearing.
10. 9. A gear pump according to claim 7 or 8, wherein the second bearing unit (44) has a second shaft seal (50) axially between the second rolling element bearing (48) and the pressure gear (24), the second shaft seal providing a fluid-tight connection of the drive shaft (26) to the housing cover (40).
11. Gear pump according to any one of claims 1 to 7, wherein the second bearing unit (44) comprises a plain bearing bushing (46).
12. The gear pump of claim 11, wherein the plain bearing bushing (46) is made of a polymer material or a composite material.
13. 13. A fuel-operated vehicle heating system having a burner region (14) to which combustion air (L) is supplied via a fan (17) and liquid fuel is supplied via a gear pump (12) according to any one of claims 1 to 12.