US20120090573A1

US20120090573A1 - Oil sump

Info

Publication number: US20120090573A1
Application number: US13/203,528
Authority: US
Inventors: Harm Siepel; Petrus Lambertus Knapen
Original assignee: DSM IP Assets BV
Current assignee: DSM IP Assets BV
Priority date: 2009-03-04
Filing date: 2010-03-02
Publication date: 2012-04-19
Also published as: CN102341572A; EP2404040A1; CN102341572B; WO2010100124A1

Abstract

The present invention relates to an oil sump, wherein the oil sump comprises an upper and a lower thermoplastic part that each contains one or more ribs and wherein the upper and lower part are being joined such that at least one rib of the upper part is joined to at least one rib of the lower part.

Description

The present invention relates to an oil sump, in particular an oil sump of an internal combustion engine for driving a motor vehicle.
In order to reduce the weight of motor vehicles, oil sumps of plastic materials are increasingly used instead of metal oil sumps. WO 03/102387 describes an oil pan comprising a shell of plastic material and a support structure having perforations, wherein the shell is formed by molding of plastic material onto said support structure, a portion of the plastic material extends through at least some of the perforations of the support structure, the edges of said perforations being embedded in the plastic material extending there through, thereby attaching fixedly the support structure to said shell. The support structure consists of two separate parts.
A disadvantage of the oil pan as described in WO 03/102387 is that it, when the oil pan is in use, radiates noise to a high extent.
The aim of the present invention is to obtain an oil sump which is light-weight and radiates less noise when in use.
It has surprisingly been found that this aim can be achieved in that the oil sump comprises an upper and a lower thermoplastic part that each contains one or more ribs and wherein the upper and lower part are being joined such that at least one rib of the upper part is joined to at least one rib of the lower part. With the oil sump according to the invention, the stiffness of the oil sump can be increased without having to increase the weight of the oil sump. It has been found that, compared to a metal oil sump, the weight of the oil sump assembly can be reduced by more than 40%, but not at the expense of the performance of the oil sump.
An additional advantage of the oil sump according to the invention is that a higher amount of oil can be stored at a given weight of the oil sump and/or at a given design space. Another advantage is that there is a more homogeneous stress distribution in the joined ribs and in the joined wall resulting in that the critical loading on the oil sump can be increased. As such, the oil sump is well able to carry the weight of the engine block so that the engine block can be placed directly onto a floor as this is generally done when the engine block is removed from a motor vehicle or before it is installed in a motor vehicle.
JP56057910U describes an oil sump containing, as a separate body from said oil sump, a balance shaft installation block with an oil scattering preventing wall that has been constructed as one body with the balance shaft installation block. The oil sump however does not contain an upper and a lower part which are joined such that at least one rib of the upper part is joined to at least one rib of the lower part.
For clarity purposes, in the oil sump according to the invention, the upper part is located on top of the lower part. As such, the total volume of the oil sump is larger than the volume of the upper part as well as of the lower part.
The joining of the ribs is preferably effected by welding or gluing. Such welding or gluing is advantageous compared to mechanical joining in that the homogeneous stress distribution in the joined ribs and in the joined wall is even more pronounced. The joining of the ribs is preferably effected by welding or gluing, more preferably by welding. More preferably, the welding is effected by laser welding, mirror welding or hot air welding.
Preferably, the upper and the lower thermoplastic part of the oil sump are preferably further joined via their respective fixing surfaces. This joining is preferably effected by welding or gluing, more preferably by welding. More preferably, the welding is effected by laser welding, mirror welding or hot air welding. In a preferred embodiment, joining the ribs of the upper and lower thermoplastic part and joining the respective fixing surfaces of the upper and lower thermoplastic part is effected in the same way and also in one operation. In a preferred embodiment, the total perimeter of the fixing surface of the upper part is smaller than the total perimeter of the fixing surface of the lower part; this results in an increase of the amount of oil that can be stored.
In a preferred embodiment, the oil sump consists of two thermoplastic parts, i.e. of the lower thermoplastic part and the upper thermoplastic part.
It has surprisingly been found that with the oil sump according to the present invention it is possible to use an oil sump that is single-walled, i.e. with only one plastic shell, while the strength of the oil sump is high enough. The use of a single-walled oil sump is advantageous as this results in the need for less thermoplastic material and thus in reduced weight compared to a double-walled thermoplastic oil sump. An additional advantage is that the manufacture of such oil sump is very simple. The oil sump of the present invention is therefore preferably single-walled.
Preferably, the oil sump contains interior ribs (ribs on the interior surface of the oil sump) and/or exterior ribs (ribs on the exterior surface of the oil sump). The ribs have the function of reinforcing the oil sump. More preferably, the oil sump contains interior ribs as well as exterior ribs. Preferably, the oil sump contains interior ribs that preferably extend, when joined, over one of the longitudinal sides of the oil sump and more preferably also over the bottom of the lower part of the oil sump. The exterior ribs are preferably provided on the other longitudinal side of the oil sump. The exterior ribs preferably extend, when joined, over the entire longitudinal exterior side of the oil sump. Preferably, the interior ribs are not connected to the wall of the longitudinal side of the oil sump on which the exterior ribs are preferably provided. The latter results in that a complete drainage of oil is possible. The oil sump preferably further contains domes in order to be able to mechanically join the oil sump to an engine block. Such a dome is preferably connected to a separate, interior bottom rib. As a result of the presence of such interior ribs and exterior ribs, the radiation of noise is further reduced. In view of noise radiation reduction, the distance between the ribs is preferably at most 30 mm, more preferably at most 25 mm and even more preferably at most 20 mm; and the distance between the ribs is preferably at least 10 mm.
The oil sump is preferably produced from polyamide. The polyamide is preferably polyamide 6 or polyamide 6,6 or a blend thereof. The oil sump is preferably produced from reinforced polyamide. Reinforcing is preferably effected by using glass fibres in a reinforcing amount, e.g., in an amount of from 5 percent by weight to 60 percent by weight, based on the total weight of the oil sump.
The oil sump of the present invention is in general a part of an oil sump assembly. Preferably, the oil sump assembly further contains (a) an engine block, (b) a gearbox or a coupling, and (c) a support bracket that is attached to the gearbox or to the coupling and to the engine block. Preferably, the bracket consists of one part. As used herein, one part may also include different parts that are attached to each other thereby forming one structural part. The use of such an oil sump assembly results in that mechanical failure of the engine is reduced or even prevented. An additional advantage of the use of such oil sump assembly is that stresses in the plastic material of the oil sump are reduced or even prevented, resulting in less oil leakage and/or in reduced chance of failure of the thermoplastic oil sump.
Preferably, the support bracket has a Young's modulus higher than 20 GPa, preferably higher than 22 GPa and more preferably higher than 25 GPa. A Young's modulus higher than 20 GPa results in that deformation of the gearbox is lowered, resulting in less mechanical failure of the engine.
The support bracket is attached to the gearbox or the coupling and to the engine block. Preferably, the support bracket surrounds a part of the oil sump. The oil sump is preferably attached to the support bracket prior to attaching the support bracket to the gearbox or to the coupling and to the engine block. This is advantageous as this results in easier assembling of the oil sump assembly. Preferably, the attaching is effecting by assembling. The assembling is preferably effected using screws or more preferably using snaps. The latter is advantageous as using snaps results in easier assembling and in that fewer parts are needed for assembling.
The thermoplastic oil sump has the function of an oil reservoir and is at the same time a structural part of the oil sump assembly. An oil sump is a reservoir for lubricating oil for an internal combustion engine for driving a motor vehicle. Internal combustion engines are lubricated by oil which is pumped into bearings and thereafter allowed to drain to the base of the engine. Oil is collected in an oil sump located at the base of the engine and oil is redistributed from the oil sump during operation of the engine. The thermoplastic oil sump is adhered to the engine block. Preferably the adhesion is effected by sealing as the sealing results in less oil leakage and even in that the oil sump assembly is tight for oil. Sealing can for example be effected by the use of a seal ring and/or of a liquid seal. The use of a liquid seal is preferred in view of the ease of assembling. The seal surface (of the thermoplastic material) of the oil sump preferably corresponds with one or more of the seal surfaces of the engine block as this results in that the chance for oil leakage is further reduced. Preferably, the seal surface of the oil sump is uninterrupted as this results in that the chance for oil leakage is further reduced.
The support bracket may be produced from a material selected from metal, thermoset plastic material, thermoplastic material and combinations thereof. In a preferred embodiment, the support bracket is produced from metal. Metal from which the support bracket may be produced include, but are not limited to, ferrous alloys, aluminum alloys and titanium alloys. Preferably, the support bracket consists of aluminum as the use of aluminum is advantageous in view of weight and stiffness.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will be more apparent from the detailed description of one preferred embodiment of an oil sump structure according to the invention, which is described as a non-limiting example with the help of the accompanying drawings.

FIG. 1 and FIG. 2 are perspective views of an oil sump according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The oil sump as shown in the figures consists of two thermoplastic parts, an upper part 1 and a lower part 2. The upper and lower part both contain interior ribs (3 a respectively 3 b) that are joined by means of a weld 4 resulting in that the oil sump contains interior ribs which extend over one of the longitudinal sides of the oil sump. The interior ribs 3 b further extend over the bottom of the lower part of the oil sump. The interior ribs 3 b and 8 are not connected to the wall of the other longitudinal side of the oil sump, resulting in an oil drain space 11. The lower and upper part both contain exterior ribs (5 a respectively 5 b) that are joined by means of a weld 6 resulting in that the oil sump contains exterior ribs which extend over the other longitudinal side of the oil sump. The oil sump further contains domes 7 in order to be able to mechanically join the oil sump to the engine block. Such a dome is preferably connected with an interior bottom rib 8. The bottom ribs 8, the interior ribs 3 a, 3 b and the exterior ribs 5 a, 5 b may be molded on the surfaces of the oil sump separately from or concurrently with the mold formation of the oil sump. Preferably, the ribs 3 a, 3 b, 5 a, 5 b, 8 are molded on the surfaces of the oil sump concurrently with the mold formation of the oil sump. In FIG. 1, the thickness of the ribs is denoted as t, the height of the ribs is denoted as h and the length of the ribs is denoted as l. The oil sump is attached to a support bracket 9. The oil sump will be adhered to the engine block. The seal surface 10 of the oil sump preferably corresponds with one or more of the seal surfaces of the engine block.

Claims

1. An oil sump, wherein the oil sump comprises an upper thermoplastic part (1) and a lower thermoplastic part (2) that each contains one or more ribs (3 a, 3 b, 5 a, 5 b, 8) and wherein the upper and lower part are being joined such that at least one rib of the upper part is joined to at least one rib of the lower part.

2. An oil sump according to claim 1, wherein the joining of the ribs is effected by welding or gluing.

3. An oil sump according to claim 1, wherein the oil sump is single-walled.

4. An oil sump according to claim 1, wherein the oil sump contains ribs on the interior surface (3 a, 3 b, 8) and ribs on the exterior surface (5 a, 5 b).

5. An oil sump according to claim 4, wherein the interior ribs (3 a, 3 b), when joined, extend over one of the longitudinal sides of the oil sump and over the bottom of the lower part of the oil sump.

6. An oil sump according to claim 5, wherein the interior ribs (3 a, 3 b) are not connected to the wall of the other longitudinal side of the oil sump

7. An oil sump according to claim 4, wherein the exterior ribs (5 a, 5 b), when joined, extend over the other longitudinal side of the oil sump.

8. An oil sump according to claim 1, wherein the upper and the lower thermoplastic part are welded or glued via their respective fixing surfaces.

9. An oil sump according to claim 8, wherein the welding is effected by laser welding, mirror welding or hot air welding.

10. An oil sump according to claim 1, wherein the oil sump consists of a reinforced polyamide.

11. An oil sump according to claim 1, wherein the thermoplastic material is a glass fibre reinforced polyamide.

12. An oil sump according to claim 10, wherein the polyamide is polyamide 6 or polyamide 6,6 or a blend thereof.

13. An oil sump according to claim 1, wherein the oil sump is a part of an oil sump assembly further containing (a) an engine block, (b) a gearbox or a coupling, and (c) a support bracket (9) that is attached to the gearbox or to the coupling and to the engine block.

14. An oil sump according to claim 13, wherein the bracket (9) consists of one part.