GB2279109A

GB2279109A - Engine oil sump

Info

Publication number: GB2279109A
Application number: GB9312673A
Authority: GB
Inventors: Paul Raymond Castro
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1993-06-18
Filing date: 1993-06-18
Publication date: 1994-12-21
Also published as: GB9312673D0

Abstract

The sump 40 has a wall 54 dividing the sump into a main region 58 and a pick-up region 56. A thermally operated valve 66 opens an aperture 64 in the dividing wall 54 only after the oil in the pick-up region warms up. When the engine is started from cold only oil from the pick-up region is circulated round the engine, being returned there by a guide 70. The valve may be a bi-metallic strip, a memory metal strip (Fig. 7) or a strip (84, Figs. 8 and 9) operated by a wax thermostat. The valve 66 may open above the normal engine operating temperature. <IMAGE>

Description

An Oil Sump Assembly The present invention relates to oil sumps for engines, and particularly engines of motor vehicles.

Known oil sumps generally comprise a casing defining a single volume in which oil is collected. Oil drains into the sump from several regions of the engine and is extracted by an oil pick-up, usually at one end of the sump. Although wiers are provided to maintain a reasonable level of oil around the pick-up during cornering, braking and accelerating, the oil circulates quite freely around the sump.

When the engine is started from cold the oil takes a considerable time to warm up and delays warming of the engine. This is disadvantageous because while the engine is below its optimum running temperature it produces more undesirable emissions and is less efficient.

Accordingly the present invention aims to provide a sump assembly which allows an engine to warm up more rapidly than is conventionally the case.

The present invention provides an oil sump assembly for an engine, the sump comprising casing means defining a sump volume, dividing means for dividing the sump volume into first and secona regions and thermally operate valve means arranged to open when the temperature of the oil in the first region increases to allow oil to flow between the first and second regions.

Preferably the dividing means comprises a wier. This allows oil to flow between the first and second regions of the sump if the oil level in either becomes undesirably high.

The valve means may conveniently be arranged to open ana close an aperture in the dividing means, and preferably comprises a flap valve.

The valve means may comprise a valve member formed of memory metal or a bi-metallic valve member. Alternatively it may include a thermostat control means.

The oil sump assembly may further comprise guide means for guiding oil draining from the engine into the first region of the sump. The oil sump assembly may further comprise oil pick-up means arrangea to extract oil from the first region of the sump for supplying to the engine.

Preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a longitudinal section through a known sump assembly; Figure 2 is a cross section on line II-II of Figure 1; Figure 3 is a longitudinal section of a sump assembly according to the invention; Figure 4 is a cross section on line IV-IV of Figure 3; Figure 5 is a plan view, partly cut away, of the assembly of Figures 3 ans 4; Figure 6 is a perspective view of an oil guide forming part of the assembly of Figures 3 to 5; Figure 7 is a perspective view of an alternative valve arrangement to that of Figures 3 to 5; Figure 8 is a perspective view of a further alternative valve arrangement; and Figure 9 is a partly exploded view of the valve arrangement of Figure 8.

Referring to Figures 1 and 2 a conventional sump comprises a casing 10 having a base 12, two end walls 14,16 and two siae walls 18, 20. Two wiers 22, 24 extend across the base 12 dividing the lower part of the sump into three regions 26, 28, 30. An oil pick-up 32 extends downwards into one of these regions 26 to extract oil from it for supplying to the engine 34. The wiers 22, 24 restrict the flow of oil along the sump, for example when the vehicle is cornering, and thereby help to maintain a satisfactory level of oil around the oil pick-up 32.

Referring to Figures 3 to 6 an oil sump assembly according to the invention comprises a casing 40 having a base 42, two end walls 44, 46 and two side walls 48, 50, and is bolted to an engine crankcase 52.

A dividing wall 54 joined to the base 42 and the side walls 48, 50 divides the sump into a pick-up region 56 and a main region 58. An oil pick-up 62 extends down from the crankcase 52 into the pick-up region 56 so that its open end 60 is near the base 42. The dividing wall 54 has an aperture 64 through it and a rectangular bi-metallic strip 66 is fastened along one edge to the dividing wall 54, on the side of the main region 58 of the sump, so that it covers the aperture 64. The lower edge 68 of tne aperture is slightly higher than the open end of the oil pick-up 62.

An oil guide, shown most clearly in Figure 6, comprises a flat guide plate 70 with an upturned rim 72 which has a flange 74 extending outwardly from its upper edge 76. The rim 72 is higher at one end than the other so that, in use, with the flange 74 hela between the crankcase 34 and the sump casing 10, one end 75 of the guide plate 70 is higher than the other end 77. The guide plate 70 has two drainage holes 78 near its lower end 77 and a further hole 80 large enough for the oil pick-up 32 to pass through during assembly. A baffle 82 extends downwards from the under side of the guide plate 70 so that it is parallel with, and slightly spaced from, the upper edge of the dividing wall 54 so that there is a narrow gap 84 between them. This ensures that oil can only flow gradually over the dividing wall 54 between the main region and the pick-up region 56 of the sump.

The operation of the sump assembly will now be described.

When the engine is started and the oil in the sump 10 is cold the bi-metallic strip 66 remains flat blocking the aperture 64. Oil is taken from the pick-up region 56 through the pick-up 62 and circulated round the engine. It then drains back onto the guide plate 70, down to its lower end 77, and through the holes 78, 80 back into the pick-up region 56 of the sump. Because only a small volume of oil is circulated it warms up relatively quickly. When the oil reaches a first predetermined temperature the bi-metallic strip bends away from the aperture 64 allowing oil to flow between the main region 58 and the pick-up region 56. This flow continues until the oil in the pick-up region falls below a second, lower, predetermined temperature, at which point the bi-metallic strip closes the aperture 64.This process continues until all of the oil in the sump has reached the first predetermined temperature and the aperture is left open so that all the oil in the sump can circulate round the engine.

In an alternative arrangement the temperature at which the aperture is opened can be set such that, under normal operating conditions, the oil in the main region 58 of the sump never reaches that temperature. This means that the oil in the pick-up region 56 is held at a substantially constant temperature. This can enable oils and clearances to be optimized for steady state temperature conditions.

Figure 7 shows an embodiment of the invention in which the bi-metallic strip as described above is replaced by a strip of memory metal 82. The memory metal remains in one position when the oil is below a certain temperature and flips to another position allowing oil to flow between the two regions of the sump when the oil temperature rises above that temperature.

Figures 8 and 9 show a third embodiment of the invention in which the aperture in the dividing wall is covered by a metal strip 84 mounted at one end on a hinge 86 and supported at the other end by a 'waxstat' thermostat device which moves the strip 84 away from the aperture when the temperature of the oil in the pick-up region rises above a first predetermined temperature and moves it back when the oil temperature falls below a second, lower, predetermined temperature.

Claims

1. An oil sump assembly for an engine, the sump comprising casing means defining a sump volume, dividing means for dividing the sump volume into first and second regions and thermally operated valve means arranged to open when the temperature of the oil in the first region increases to allow oil to flow between the first and second regions.

2. An oil sump assembly according to claim 1 wherein the dividing means comprises a wier.

3. An oil sump assembly according to claim 1 or claim 2 wherein the valve means is arrangea to open an aperture in the dividing means.

4. An oil sump assembly according to any foregoing claim wherein the valve means comprises a flap valve.

5. An oil sump assembly according to any foregoing claim wherein the valve means includes a valve member formed of memory metal.

6. An oil sump assembly according to any one of claims 1 to 4 wherein the valve means includes a bi-metallic valve member.

7. An oil sump assembly according to any foregoin claim wherein the valve means includes a thermostat control means.

8. An oil sump assembly according to any foregoing claim further comprising guide means for guiding oil draining from the engine into the first region of the sump.

9. An oil sump assembly according to claim 8 wherein the guide means includes baffle means for preventing the rapid flow if oil between the first and second regions of the sump.

10. An oil sump assembly according to claim 9 wherein the baffle means cooperates with the dividing means to prevent said rapid flow.

11. An oil sump assembly according to any foregoing claim further comprising oil pick-up means arranged to extract oil from the first region of the dump for supplying to the engine.

12. An oil sump assembly substantially as hereinbefore described with reference to Figures 3 to 6, Figure 7, or Figures 8 and 9 of the accompanying drawings.

13. An engine including an oil sump assembly according to any foregoing claim.