GB2308343A - Cooling vents in a sound-absorbing enclosure for a vehicle drive unit - Google Patents

Description

1 AN ENCLOSURE FOR A VEHICLE DRIVE UNIT 2308343 The invention relates to

an enclosure for a vehicle drive unit, in particular for commercial vehicles, in the form of a hollow housing of soundinsulating material surrounding a motor and transmission of a vehicle.

For sound-proofing reasons, enclosures of soundinsulating material are provided to reduce the noise occurring in the operation of motor vehicles, which enclosures substantially completely enclose the vehicle drive units, generally units comprising the engine and transmission. Measures of this type are of particular significance in commercial vehicles, in particular heavy goods vehicles which have relatively large and correspondingly noisy engines. To ensure that enclosures of this type provide the desired effect in all operation conditions of the drive unit, as a rule they are designed for the maximum engine output. This means relatively high outlay for the design of the cooling system, since the enclosure is effective not only with regard to noise formation but also from a thermal aspect. Enclosure designs, which make possible good sound insulation without excessively insulating the drive from a thermal aspect, if available, are especially costly.

This means that the engine cooling systems reach the limit of the capacity and can only meet requirements when using larger radiators andlor fans with greater output. Optionally, in these cases the fans operate in an unstable range, i.e. at the pump limit. However, any enlargement of the cooling units, if it is at all possible in respect of space requirements, leads to greater weight and an increase in costs. Almost unsurmountable difficulties have currently arisen, particularly in the context of powerful engines with 2 high torque at relatively low rpm but also with high engine output at rated rpm.

Therefore, the invention is based on the object of devising a soundinsulating enclosure of the type defined, which makes it possible, even with powerful engines, to provide sufficient cooling even at operation under full load, without incurring unjustifiable expense.

According to the present invention, there is provided an enclosure for a vehicle drive unit comprising a hollow housing of sound-insulating material surrounding a motor and a transmission of a vehicle, characterised in that the enclosure comprises flap-like movable elements which are opened as a function of the temperature of the drive unit and/or of a parameter associated therewith.

The manner in which this object is achieved is based on the consideration that the full output of the drive at low travel speeds, at which the air flow rate is low, is required only in exceptional circumstances and mostly only for a short time. In these cases, the enclosure according to the invention makes it possible to increase temporarily the air flow through the radiator and along the engine and transmission so as to increase the cooling action. In this way it is in any case ensured that overheating of the entire drive system is obviated, without creating unacceptable noise pollution of the environment.

Insofar as in the present context the opening elements of the enclosure are designated as flaps, it is to be noted that this term is intended to include not only flaps in the narrower sense but also those with a hingelike articulation. Since the material used for the enclosures is mostly flexible within certain limits, its elasticity can also be used for the temporary formation of openings. Slide designs may also be considered. The important consideration is merely to form temporary 3 openings in the enclosure so as to provide an increased air flow through the radiator.

The opening and closing of the flaps can be effected with different actuating elements, for example hydraulic or pneumatic cylinders or electric servomotors. The use of bimetallic elements may also be considered.

Primarily, the cooling water temperature is used as parameter for controlling the opening movement. Likewise, however, the oil temperature in a retarder, the exhaust gas temperature or the air temperature in the enclosure also come into consideration. The internal pressure in the enclosure may also be used. of course, the outside temperature does in fact also have an influence on the temperature development of the drive but its effect is automatically included in the aforementioned parameters, such as the cooling water temperature. A special consideration of the outside temperature is taken into account if the power output from the drive system is used as a scale for the heating to be expected.

The flaps are preferably disposed in areas in which there is comparatively little sound emission and they are arranged overlapping the adjoining enclosure parts so that direct sound bridges are obviated. The opening exposed by the flap may also be of labyrinthine configuration.

The invention may also be used to accelerate the cooling of the drive unit after the engine has been switched off. When the engine is switched off the circulation of the cooling water stops and there is no longer any cooling action of the air flow and of the fan, so that often a reheating effects occurs, which can even result in enclosure fires. Therefore, by opening flaps on the upper side and lower side the enclosure can be ventilated and thus the cooling of the drive unit accelerated. For example, the plus signal of the 4 is generator can be used to determine the fact that the motor is switched. The failure of this signal indicates that the engine and thus the generator are inoperative.

The measures according to the invention can be undertaken, without any alterations to the cooling system being required. Even conventional enclosures can be substantially retained and merely need to be supplemented.

Preferred examples of embodiment of the invention will be illustrated in more detail below with reference to the accompanying drawings.

Figures 1 to 3 show a schematic cross-section, a longitudinal section and a horizontal section through one embodiment of a drive and cooling system with an enclosure according to the invention; Figures 4 to 6 are corresponding illustrations of another embodiment of the enclosure.

In Figures 1 to 3, there can be seen a drive unit comprising an engine which is designated 10, an adjoining transmission which is designated 12 and an adjoining clutch or retarder which is designated 14. According to one direction of travel, this drive unit is disposed from the right to the left in Figures 2 and 3. Therefore, on the left-hand side there is situated a cooling unit, which comprises in succession a condenser 16 for an air-conditioning unit, an intercooler 18 and an engine radiator 20, downstream from which there is a fan frame 22, which is funnel-shaped in the broader sense, passes over into an annular fan 24. The aforementioned fan frame 22 enters an enclosure, generally designated 26, inside which are situated the annular fan 24 and also the drive unit, comprising engine 10, transmission 12 and clutch or retarder 14.

According to Figure 2 this enclosure 26 has a labyrinthine opening 28 in the region behind the engine 10, which permanently allows the outlet of air to a certain extent from the enclosure, as is indicated by an arrow 30. Another permanent air outflow can take place, in a manner not shown in detail, in accordance with an arrow 32 along the transmission 12 and the clutch or retarder 14 towards the rear side of the enclosure.

In accordance with the present invention, according to Figure 2 a flap 34 is provided on the underside of the enclosure 26 at the transition from the annular fan 24 into the engine 10, which flap is mounted in hinge-like manner at its front end 36 and can be opened and closed by means of a actuating element 38. It is evident that the flap, even in the open position shown in Figure 2, overlaps the rearwardly adjoining lower wall of the enclosure 26 so as to obviate the formation of a direct sound bridge. When the flap is open, air which in accordance with an arrow 40 is delivered by the annular fan 24, exits downwards at least partly corresponding to an arrow 42 after passing through the annular fan 24. In this way the back pressure in the enclosure is reduced and a higher air throughput through the annular fan 24 is made possible in conjunction with a correspondingly more powerful cooling action.

It is evident from the horizontal section according to Figure 3 that two flaps 44 and 46, which can be swung out laterally, are additionally provided, which are also situated at the transition between the annular fan 24 and the engine 10 and are mounted in hinge-like manner at their front edges 48,50. A common actuating element 52 serves to swing out the flaps 44,46 and thus enables the air streams to flow out, which are indicated by the arrows 54,56 in Figure 3. In this case too, it is evident that the flaps 44,46 clearly overlap the rearwardly adjoining wall material of the enclosure 26.

A cooling-water system 58 is indicated in chain line in Figures 2 and 3. A temperature sensor 60 is disposed in the cooling water, the signals of which are 6 emitted via a line 62 to a control unit 64. The control unit 64 is in turn connected via further lines 66,68 to the actuating elements 38,52. In this way it is indicated that the flaps 34 and 44, 46 can be opened and closed via the control unit 64 as a function of the cooling-water temperature. As indicated in the foregoing, other parameters may also be used as control variables. This is indicated in Figures 2 and 3 by a further line (without reference numeral) entering the control unit 64.

The basic principle described above is put into effect in the second embodiment according to Figures 4 to 6. Components which have already been described with reference to Figures 1 to 3 are provided with like reference numerals and are will not be described again in detail. The flap 34 to be opened downwards in the region behind the annular fan 24, is also provided in the embodiment according to Figures 4 to 6.

Instead of the permanently open labyrinthine opening 28 in the upper region of the enclosure behind the engine 10, in the second embodiment there is provided a movable, adjustable flap 70 which is mounted in the manner already described at its front edge 72 in hinge-like fashion on the enclosure 26. The flap 70 is also connected to a actuating element which is not shown in Figure 5. It allows the outflow of an air stream in accordance with an arrow 74.

In the vicinity of the transmission 12 and of the clutch or retarder 14, the cross-sectional area of which is substantially smaller than that of the engine 10 and in the region of which the enclosure is reduced accordingly in diameter, flaps 76,78 and 80,82 respectively are disposed on the upper side and lower side of the enclosure and once again on their front edges (not shown) are mounted in hinge-like manner on the enclosure, are arranged overlapping in the manner already described and are provided with a actuating 7 element not shown. These flaps allow the outlet of air flows in accordance with arrows 84,86 and 88,90 respectively.

The arrangement of flaps may be modified further with respect to the embodiments described. They do not have to be pivotable flaps but it is also possible for parts of the enclosure to be raised outwards.

Of course, the arrangement of the flaps can be chosen with respect to the desired cooling effect. It is evident that flaps 34 provided further forwards according to Figures 2 and 5 contribute in particular to increase the passage of cooling air through the radiator, whereas the flaps 76,78,80, 82 according to Figure 5 situated in the rear region of the enclosure additionally make possible a cooling air flow along the entire drive unit up to the transmission and the clutch or retarder. The number and size of the flaps is to be chosen so that it is reliably ensured that any overheating of the drive unit is obviated even when there is relatively protracted full power output.

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Claims (14)

1. An enclosure for a vehicle drive unit, comprising a hollow housing of sound-insulating material surrounding a motor and a transmission of a vehicle, characterised in that the enclosure comprises flap-like movable elements which are opened as a function of the temperature of the drive unit and/or of a parameter associated therewith.

2. An enclosure according to Claim 1, characterised in that the movable elements are associated with control members.

3. An enclosure according to Claim 1 or 2, characterised in that position of the movable elements can be controlled as a function of the coolingwater temperature.

4. An enclosure according to Claim 1 or 2, characterised in that position of the movable elements can be controlled as a function of the engine-oil temperature.

5. An enclosure according to Claim 1 or 2, characterised in that position of the movable elements can be controlled in a vehicle with a retarder as a function of the retarder-oil temperature.

6. An enclosure according to Claim 1 or 2, characterised in that position of the movable elements can be controlled as a function of the air temperature in the enclosure.

7. An enclosure according to Claim 1 or 2, characterised in that position of the movable elements can be controlled as a function of the engine power output.

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8. An enclosure according to any one of Claims 1 to 7, characterised in that the movable elements are associated with control members which are pneumatic or hydraulic cylinders.

9. An enclosure according to any one of Claims 1 to 7, characterised in that the movable elements are associated with control members which are electric motors.

10. An enclosure according to any one of Claims 1 to 7, characterised in that the movable elements are associated with control members which are bimetallic elements.

11. An enclosure according to any one of the preceding Claims, characterised in that at one edge the movable elements are pivotably connected to a wall of the enclosure and overlap the wall at the opposite edge.

12. An enclosure according to any one of the preceding Claims, characterised in that the openings exposed by the flaps are of labyrinthine configuration.

13. An enclosure according to any one of the preceding claims having a permanent aperture for receiving air flow drawn into the enclosure by a fan of the drive unit, wherein the movable elements are opened to increase rate of flow of air within the enclosure.

14. An enclosure for a vehicle drive unit substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.