GB2457382A

GB2457382A - A device which convectively cools a drive train component

Info

Publication number: GB2457382A
Application number: GB0902481A
Authority: GB
Inventors: Robert Meier; Holger Maier; Gianluca Magistro; Anestis Savvidis; Bernd Jachowski; Tom Gurtler; Christopher Sachs
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 2008-02-16
Filing date: 2009-02-13
Publication date: 2009-08-19
Anticipated expiration: 2029-02-13
Also published as: GB2457382B; DE102008009523A1; GB0902481D0

Abstract

A device for the convective cooling of a drive-train component, e.g. a rare axle differential 1, of a motor vehicle comprises a thin walled shaped flow body 15 having a shell-type formation which provides a gap 17 for passage of air between a shell-type region (16, fig 3) of the flow body 15 and an underside of the rare axle differential 1. When the vehicle is moving, cold ambient air from underbody flow is guided into the gap 17 and consequently deflected by the flow body 15 to a hot region of the differential 1. Air flow enters the gap 17 substantially parallel to the underbody and issues from the gap 17 in a direction of the underbody. The flow body 15 may be fixed to a rare transmission housing part 2 by means of two lower screws 10 which also screws together housing parts 2 and 3.

Description

A device for the convective cooling of a drive-train component of a motor vehicle The invention relates to a device for the convective cooling of a drive-train component of a motor vehicle, wherein the drive-train component is arranged in the region of the underbody of the vehicle and the device deflects an underbody air flow around the drive-train component when the vehicle is moving.

A device of the aforementioned type is known from JP 10110812 A. The vehicle described therein has a drive-train component which is formed as a rear-axle differential. In the direction of travel, the device, which is formed as a plate, is arranged behind the rear-axle differential between the latter and a spare wheel. The plate is arranged perpendicularly to the underbody, transversely to the direction of travel, and is connected to the underbody in the region of its upper end. Owing to the plate, the underbody air flow is stemmed in front of the plate and is deflected around it. The underbody air flow is also deflected around the rear-axle differential, whereby the latter is convectively cooled.

Further devices for cooling a transmission part, in particular a rear-axle differential, are known from DE 103 14 356 Al, DE 103 59 009 Al and DE 38 04 795 Al.

The present invention seeks to develop a device of the initially mentioned type in such a way that it can be manufactured in a simple and inexpensive manner, can be formed with a low weight and is easy to mount.

In the device of the initially mentioned type, the device is fixed directly to the drive-train component.

According to the invention, it is not necessary to fix the device to the underbody of the vehicle. Instead, the device can be fixed to a suitable point on the drive-train component, in particular from the point of view of optimum flow towards the device and thus optimum convective cooling of the drive-train component. As the device is fixed directly to the drive-train component, the device can be structurally configured substantially from the point of view of its function, namely the deflection of the underbody air flow around the drive-train component. It is only necessary to provide the device with those component parts which serve to fix the device to the drive-train component. This allows the device to be manufactured in a simple and inexpensive manner and with a low weight. As the device is fixable directly to the drive-train component, it can be mounted easily.

The drive-train component is preferably a transmission part of the motor vehicle, in particular a rear-axle differential. This is usually formed as an outwardly curved body, wherein two housing parts of the rear-axle differential form the outer shape thereof. The shape of the device is preferably adapted to the shape of the drive-train component, in particular the rear-axle differentiai, so that a gap for the passage of air is formed between the device and the drive-train component.

It is regarded as particularly advantageous if the device is formed as a flow body, in particular a thin-wailed shaped body. The configuration of the device as a flow body permits particularly favourable deflection of the underbody air flow around the drive-train component. In this context, a thin-walled shaped body is taken to mean a body which has low flow resistance and is suitable for deflecting the air flow and also has adequate strength.

According to a preferred concrete configuration of the device, it is provided that the flow body has a shell-type formation, and the gap for the passage of the air is formed between a shell-type region of the flow body and the drive-train component. In particular, the gap is formed between the shell-type region of the flow body and an outwardly curved housing part of the drive-train component.

The flow body is preferably arranged in such a way that the underbody air flow enters the gap substantially parallel to the underbody and issues from the gap in the direction of the underbody. This guiding of the air flow through the flow body ensures that the air flow flows along the drive-train component over a relatively long distance.

In particular, the device is screwed to the drive-train component. It is regarded as advantageous if fixing means for fixing the device to the drive-train component also serve to connect housing parts of the drive-train component. Accordingly, the device according to the invention can be jointly mounted when the drive-train component, in particular the rear-axle differential, is assembled, specifically when the housing parts of the rear-axle differential are connected.

In the region of the drive-train component, in particular the rear-axle differential, the device according to the invention allows cold ambient air from the underbody flow to be guided to the hot regions of the differential gear. By increasing the heat transfer coefficient and by lowering the ambient temperature, the convective dissipation of heat from the gear is increased and the gear temperature is thus held below the permitted limit value.

Further features of the invention will become apparent from the sub-claims, the following description of the drawings and the drawings themselves.

A preferred embodiment of the invention will be further described in the following description and is shown in the drawings, wherein: Fig. 1 shows a side view of a rear-axle differential with a device fixed thereto, seen horizontally, transversely to the direction of travel of the motor vehicle; Fig. 2 shows a three-dimensional view of the parts shown in Fig. 1, seen obliquely from the rear; Fig. 3 shows a section along the line Ill-Ill in Fig. 2.

The motor vehicle drive-train component, which is only shown very simply in Figs. 1 and 2 and is a rear-axle differential 1, has -relative to the normal direction of travel of the motor vehicle -a rear housing part 2 and a front housing part 3. The parting plane of the two housing parts 2 and 3 extends substantially perpendicularly arid transversely to the direction of travel and is designated by the reference numeral 4. On its side remote from the housing part 2, the housing part 3 receives an input shaft 5 of the rear-axle differential 1. In the region of the parting plane 4, the rear-axle differential 1 is provided on both sides with openings 6, through which output shafts (not shown) of the rear-axle differential 1 are insertable. The two housing parts 2 and 3 are connected by means of eight screws. Adjacent to the two openings 6, four screws 7 are provided which extend inside through bores in projections 8 of the rear housing part 2 and are screwed into threaded bores formed in projections 9 of the front housing part 3. Four further screws 10 for the connection of the two housing parts 2 and 3 are provided in the upper and the lower region of the rear-axle differential 1. Each screw 10 extends inside a through bore 11 in a projection 12 of the rear housing part 2 and is screwed into a threaded bore 13 in a projection 14 of the front housing part 3.

While the two upper screws 10 serve exclusively to connect the two housing parts 2 and 3 in the upper region of the rear-axle differential 1, the two lower screws 10 have the additional function of fixing the device according to the invention for the convective cooling of the rear-axle differential 1 directly to the rear-axle differential 1, specifically the rear housing part 2, the device being formed as a flow body 15.

The flow body 15 has a shell-type formation, and a gap 17 for the passage of air is formed between the shell-type region 16 of the flow body and the underside of the rear-axle differential 1. The entry of air into the gap and the exit of air from the gap is illustrated in Fig. 1 by means of two arrows in each case. The gap 17 tapers towards the exit so that the air flows through the gap 17 in an accelerated manner. Cold ambient air from the underbody flow, the flow direction of which is illustrated in Fig. 1 by the two arrows representing the inflow, is thus guided into the gap 17 and consequently to the hot region of the rear-axle differential 1.

By increasing the heat transfer coefficient and by lowering the ambient temperature, the convective dissipation of heat from the gear is increased and the gear temperature is thus held below the permitted limit value.

Therefore, as can be seen from the view in Fig. 1, when the vehicle is moving the flow body 15 deflects the underbody air flow around the rear-axle differential 1 in the lower region thereof in accordance with the two arrows shown on the left, wherein the underbody air flow enters the gap 17 substantially parallel to the underbody and issues from the gap 17 in the direction of the underbody, as illustrated by the two arrows shown on the right in Fig. 1.

Fig. 3 shows the actual fixing of the flow body 15 to the rear transmission part 2. The flow body 15 has two pot-shaped recesses 18, the base of which is provided with a through hole for the insertion of the screw shank 19. By means of the two lower screws 10, the flow body 15 and the housing parts 2 and 3 are screwed together.

List of reference numerals 1 Rear-axle differential 2 Rear housing part 3 Front housing part 4 Parting plane Input shaft 6 Opening 7 Screw 8 Projection 9 Projection Screw 11 Through bore 12 Projection 13 Threaded bore 14 Projection Flow body 16 Shell-type region 17 Gap 18 Recess 19 Screw shank

Claims

Claims 1. A device for the convective cooling of a drive-train component of a motor vehicle, wherein the drive-train component is arranged in the region of the underbody of the vehicle and the device deflects an underbody air flow around the drive-train component when the vehicle is moving, wherein the device is fixed directly to the drive-train component.
2. A device according to claim 1, wherein the drive-train component is a transmission part of the motor vehicle, in particular a rear-axle differential.
3. A device according to claim 1 or 2, wherein the device is formed as a flow body, in particular a thin-walled shaped body.
4. A device according to claim 3, wherein the flow body has a shell-type formation, and a gap for the passage of air is formed between a shell-type region of the flow body and the drive-train component.
5. A device according to claim 4, wherein the gap is formed between the shell-type region of the flow body and an outwardly curved housing part of the drive-train component.
6. A device according to claim 4 or 5, wherein the flow body is arranged so that the underbody air flow enters the gap substantially parallel to the underbody and issues from the gap in the direction of the underbody.
7. A device according to any one of claims 1 to 6, wherein the device is screwed to the drive-train component.
8. A device according to any one of claims 1 to 7, wherein fixing means for fixing the device to the drive-train component serve to connect housing parts of the drive-train component.
9. A device for the convective cooling of a drive-train component of a motor vehicle, substantially as hereinbefore described with reference to the accompanying drawings.
10. A Motor vehicle, comprising a device according to any one of the preceding claims.