GB2560321A

GB2560321A - Engine undercover

Info

Publication number: GB2560321A
Application number: GB1703578.3A
Authority: GB
Inventors: Kremheller Andreas
Original assignee: Nissan Motor Manufacturing UK Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2017-03-06
Filing date: 2017-03-06
Publication date: 2018-09-12
Anticipated expiration: 2037-03-06
Also published as: GB2560321B; GB201703578D0

Abstract

A vehicle engine undercover assembly 14 for a vehicle is provided that comprises at least one substantially polyhedral-shaped vortex generator 20 in the airflow passing under the vehicle. Vortex generator 20 comprises at least one front-facing inclined surface, forming a leading surface of vortex generator 20, and at least one rear-facing surface forming a trailing surface of vortex generator 20 that further comprises an airflow outlet (50, Figure 4A) communicating between an interior space of the vehicle and the underside of the vehicle, which may increase aerodynamic and acoustic performance and which may also generate a pressure difference as well as cooling an engine bay. Suitably, a plurality of pyramidal vortex generators 20 may be provided and each may have a height between 15 mm and 25 mm and/or a length of double its height. Ridges 25 may also be provided on undercover 14 and channels may be defined between ridges 25.

Description

(71) Applicant(s):

Nissan Motor Manufacturing (UK) Ltd (Incorporated in the United Kingdom)

Nissan Technical Centre Europe,

Cranfield Technology Park, Bedfordshire, MK43 0DB, United Kingdom (72) Inventor(s):

Andreas Kremheller (74) Agent and/or Address for Service:

Nissan Motor Manufacturing (UK) Ltd Nissan Technical Centre Europe,

Cranfield Technology Park, Bedfordshire, MK43 0DB, United Kingdom (51) INT CL:

B62D 35/02 (2006.01) (56) Documents Cited:

DE 003711981 A1 DE 102007053569 A1

DE 102006046814 A1 US 5513893 A US 20130026783 A1 (58) Field of Search:

INT CL B62D

Other: EPODOC, WPI, Patent Fulltext (54) Title of the Invention: Engine undercover

Abstract Title: Engine undercover with vortex generators (57) A vehicle engine undercover assembly 14 for a vehicle is provided that comprises at least one substantially polyhedral-shaped vortex generator 20 in the airflow passing under the vehicle. Vortex generator 20 comprises at least one front-facing inclined surface, forming a leading surface of vortex generator 20, and at least one rearfacing surface forming a trailing surface of vortex generator 20 that further comprises an airflow outlet (50, Figure 4A) communicating between an interior space of the vehicle and the underside of the vehicle, which may increase aerodynamic and acoustic performance and which may also generate a pressure difference as well as cooling an engine bay. Suitably, a plurality of pyramidal vortex generators 20 may be provided and each may have a height between 15 mm and 25 mm and/or a length of double its height. Ridges 25 may also be provided on undercover 14 and channels may be defined between ridges 25.

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Engine Undercover

Field of the Invention

The present invention relates to an engine undercover for a vehicle, in particular aerodynamic features of the engine undercover that improve aerodynamic and noise performance of a vehicle.

Background of the Invention

Air flowing under a moving vehicle is a source of aerodynamic drag, and also noise vibration and harshness (NVH) due to, for example, wind noise.

When a vehicle is in motion, the air moving past the front of the vehicle creates a low pressure fast-moving airflow to the underside of the car. Drag originates from the pressure difference between the stagnation pressure at the front of the vehicle and the base pressure at the rear. The drag can therefore be reduced by reducing the difference in these pressures. Reducing drag is desirable, as it leads to lower fuel consumption.

Additionally, it is desirable to reduce noise vibration and harshness in moving vehicles. This can be done by improving aerodynamic characteristics of the vehicle.

It is possible to improve aerodynamic and noise performance by covering the underside of a vehicle. For example, GB 1302177.9 (Nissan) discloses a beam cover that provides improved aerodynamic efficiency by deflecting air from the axle beam of the rear suspension.

In another example, WO201148163 (JLR) places blades under a vehicle so as to protrude into the airflow and disrupt airflow, which can improve aero and noise performance. The drawbacks of this arrangement are that the air dam-like configuration is not aerodynamically efficient.

In another example, FR3017100 discloses a pair of blades to break the airflow. This arrangement also has limited improvement over yaw angles. Drawbacks to the blade/vane setup include that is sensitive to angle of wind, and that they won’t produce strong enough effects until reaching airflow speeds that begin to cause adverse aerodynamic effects.

Accordingly, it is an object of the invention to provide improved aerodynamic and noise functionality in a vehicle over previous known solutions.

Summary of the Invention

According to the aspects of the present invention there is provided an apparatus, as claimed in the appended claims.

In one aspect of the invention there is provided a vehicle engine undercover assembly for a vehicle, the undercover assembly comprising an engine undercover arranged to cover the underside of a vehicle, the undercover assembly further comprising at least one substantially polyhedral-shaped vortex generator disposed in the airflow passing under a vehicle in motion, the vortex generator comprising:

At least one surface oriented substantially towards the front of the vehicle to form at least one leading surface of the vortex generator;

At least one surface oriented substantially towards the rear of the vehicle to form at least one a trailing surface of the vortex generator, wherein the trailing surface further comprises an airflow outlet communicating between an interior space of the vehicle and the underside of the vehicle.

The airflow outlet, in use, causes a pressure differential between an interior space of the vehicle and the underbody of the vehicle. The airflow outlet, in use, performs as an engine bay air cooling mechanism dragging airflow through the engine bay while advantageously adding to the aerodynamic effect.

Each vortex generator may have two leading surfaces. The vortex generator may be substantially pyramidal in shape.

The undercover may have multiple vortex generators placed in an evenly-spaced relationship across the undercover, the leading surface or surfaces of the vortex generators facing against the direction of airflow.

The vortex generated at the edge of such a three-dimensional, delta-wing-shaped vortex generator keeps its strength in the flow downstream of the edge since it only weakly interferes with the vortex generator itself. Thus the engine undercover controls three-dimensional flow separation and produces a stronger vortex and less intrinsic drag than, for example, blade-type geometry. Such delta-wing-shaped vortex generators will also provide better performance over variable angles of attack. This means that drag is reduced and flow separation is controlled over the length of the engine undercover, improving general aerodynamic performance, and also the reducing associated acoustic noise.

Using three-dimensional vortex generators advantageously doesn’t block airflow to like conventional air-dams and so produce less drag than vane/blade examples, which break the flow and have a bigger frontal area that increases drag.

Pairing the vortex generators with the airflow outlets helps control the smooth flow of air down the length of the undercover, amplifying the aerodynamic effect created by the vortex generators and decreasing adverse acoustic effects caused by the airflow. The vortex generator generates and area of low pressure behind the generator, effectively extracting air from the vehicle interior space through the airflow outlet.

The airflow outlets advantageously exploit the pressure differential between the engine bay and the underside of the vehicle caused by the vortex generators as well as creating cooling effects in the engine bay. This outlet airflow increases aerodynamic benefit and increases acoustic performance.

The vehicle engine undercover assembly further comprises channels paired with the vortex generators to aid controlling airflow towards the rear of the vehicle.

The channels are defined by ridges in the engine undercover. The ridges and channels also increase structural rigidity of the undercover assembly.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a vehicle front end with undercover aerodynamic features in accordance with an embodiment of the invention;

Figure 2 shows an engine undercover in accordance with an embodiment of the invention;

Figure 3 shows airflow detail of figure 2;

Figure 4A shows a plan view of an embodiment of the invention in more detail;

Figure 4B shows a side view of an embodiment of the invention in more detail.

Detailed description of the drawings

In the drawings, like parts are denoted by like reference numerals.

Figure 1 shows the front end 10 of a vehicle that is fitted with an engine undercover 15. The engine undercover extends along the underside of the vehicle and includes aerodynamic features in the form of three- dimensional shaped vortex generators 20.

The engine undercover extends from the front to the rear of the vehicle it is fitted onto. The size and shape of the undercover 15 is dictated by the dimensions of the vehicle engine bay and other mechanical strictures imposed by the vehicle, such as vehicle width and ground clearance.

Inset in Figure 1 shows the aerodynamic features in the form of the vortex generators 20 more clearly.

Figure 2 shows the engine undercover 15 of figure 1 in in more detail. The engine undercover 15 has a front end 12 and rear end 14, defined as the portions towards the front end of a vehicle, and backwards to the rear end of a vehicle respectively.

Vortex generators 20 are placed towards the front end 12 of the engine undercover 15. The vortex generators are placed in an evenly spaced relationship to each other transversely across the width of the undercover 15, that is, with front facing into the direction of airflow when the vehicle is moving in forward direction. The vortex generators also include airflow outlets 35 which communicate between an interior space (not shown) of the vehicle and the underside of the vehicle. In use, the interior space is the engine bay of the vehicle the undercover 15 is fitted to.

The engine undercover also includes ridges 25 and channels 30.

The vortex generators 20 are shown arranged in pairs but can be in in any configuration that provides even coverage across the undercover by the vortices the generators produce, that is, produce the desired aerodynamic effect across the width of the undercover 15.

Referring also to figure 3 and 4, The vortex generators 20 are substantially polyhedral-shaped, that is they are substantially three-dimensional shape, as opposed to two-dimensional flat blades or vanes. They vortex generators 20 have leading edge surfaces 50, and trailing edge surfaces 55. Leading edge surfaces 50 face substantially towards the front end 10 of the vehicle, that is, the front end 12 of the engine undercover, and the trailing edge surface face 55 substantially towards the rear end 14 of the engine undercover. The trailing edge surface face 55 contains the airflow outlet 35. The airflow outlet may form part or all of the available surface area of the trailing edge surface 55.

The ridges 25 form channels 30 downstream from the vortex generators as shown. The channels 30 run longitudinally down the engine cover 15. A channel may also be formed by a ridge 25 and a sidewall 27 of the engine undercover 15.

Further cooling holes (not shown) may be provided downstream from the vortex generators 20. These can be provided in additional to or as alternative to the airflow outlets 35 in the vortex generators 20.

Figure 3 schematically shows airflow over the engine undercover 15.

The vortex generators 20 in conjunction with the airflow outlets 35 control airflow along the undercover 15 and induces momentum in the airflow. This reduces drag and improves wind noise from pressure fluctuation.

In normal use, a vehicle is in forward motion, and airflow is along the engine undercover 15 from the front end 12 to rear end 14, such that the vortex generators will generate vortices in the airflow. Airflow is indicated by arrowed lines.

Integrating the vortex generators 15 airflow outlets 35 into a single undercover provides synergistic benefit: the vortex generators 20 create vortices which are also advantageously channelled along the engine undercover by the channels 30.

Additionally, the airflow outlets 35 provide benefit by creating a pressure differential between the engine bay cavity and the underbody of the vehicle. The vortex generator generates a vortex which generates a low pressure area behind the generator 20, indicated by shaded area 47, drawing air from the engine bay. This assists air-cooling airflow in the engine bay and introduces momentum into the airflow along the underside of the vehicle. Introducing momentum to airflow means that separation of airflow under the vehicle is reduced, controlling the boundary layers under the vehicle, improving aerodynamic performance and reducing noise.

The channels 30 help control the smooth flow of air down the length of the engine undercover 15 and provide structural stability to the undercover 10.

Figures 4A and 4B show the vortex generators 20 in more detail. The vortex generators shown in this embodiment are substantially delta or substantially pyramidal in shape, with two substantially flat surfaces 50 facing toward the front 12 of the engine cover 15, and one substantially flat surface facing toward the rear end 14 of the of the engine cover 15. The face facing toward the rear end 14 of the engine cover 15 is the airflow outlet comprising a channel that communicates between the interior space, for example engine bay, and the underside of the vehicle.

The orientation of the vortex generators 20 can be adjusted to optimise performance according to placement on the engine undercover 15, and according to requirement of the vehicle to which the undercover is fitted. The vortex generators 20 may be substantially aligned with the longitudinal axis of the undercover 15, that is, from the front end 12 to rear end 14, thus aligned with notional longitudinal axis of the vehicle onto which the undercover 15 is fitted.

In the example show in figure 4B, the relative dimensions of the vortex generators 20 is that is one unit high and two units in length. This may be varied to be tuned aerodynamic characteristics of a given vehicle.

The height of the vortex generators 20 can be tuned to optimise aerodynamic and noise performance of different vehicles. The optimum height of the vortex generators 20 is equivalent to the thickness of the boundary layer on the underside of the vehicle, that is, between 15mm to 25 mm.

This means that the effect of the vortex generators 20 is strong enough to have an effect, so size is based on airflow. Therefore the actual size will be determined by the length of the undercover.

The vortex generated at the edge of such a delta-wing-shaped vortex generator keeps its strength in the flow downstream of the edge since it barely interferes with the vortex generator itself. This, the undercover controls three-dimensional flow separation and produces a stronger vortex, less intrinsic drag than, for example, blade geometry. Such delta-wing-shaped vortex generators will also provide better performance over variable angles of attack. This means that drag is reduced and flow separation is created and controlled over the length of the engine undercover, and associated acoustic noise.

A three-dimensional vortex generator advantageously handles a wide range of flow directions, so that the actual vortex generated is stronger than a comparable vane/blade vortex generator, that is, it produces a stronger vortex size for size, and the frontal projected area is smaller so that aerodynamic performance is increased, leading to stronger vortex.

Therefore the vortex generators 20 can present a smaller frontal area to achieve increased aerodynamic and noise performance, decreasing separated flow along the underside of the vehicle results in less noise.

Various modifications will be apparent to those skilled in the art.

The vortex generators 20 may be substantially symmetric as shown, or asymmetric to take into account vehicle body shape, or topology of the engine undercover.

Alternative shapes and surfaces may be used. For example, curved surfaces (general concave or convex) on the vortex generators 20 may be used.

The shape of the vortex generators can be consistent transversely across the engine undercover 15, or can be varied transversely across the engine undercover 15 to increase effects taking into account vehicle shape and I or undercover topology.

Likewise the size and placement of ridges 25 and corresponding channels 30 may be adjusted to best use of space dictate by vehicle shape and build features, for example, lengthened or shortened according to available space, or angled away from the longitudinal axis of the undercover 15 or the vehicle itself.

The size and placement of the cooling holes 35 on the engine undercover can be varied according to engine bay requirements. For example to maximise the effect of the cooling holes 35, they may be placed correspond to features in the engine bay above the undercover 15 to optimise cooling effects in the bay.

Claims

1. A vehicle engine undercover assembly for a vehicle, the undercover assembly comprising an engine undercover arranged to cover the underside of a vehicle, the undercover assembly further comprising at least one substantially polyhedral-shaped vortex generator disposed in the airflow passing under a vehicle in motion, the vortex generator comprising:

a. at least one inclined surface oriented substantially towards the front of the vehicle to form at least one leading surface of the vortex generator;

b. at least one surface oriented substantially towards the rear of the vehicle to form at least one a trailing surface of the vortex generator, wherein the trailing surface further comprises an airflow outlet communicating between an interior space of the vehicle and the underside of the vehicle.

2. A vehicle engine undercover assembly as claimed in claim 1 wherein the airflow outlet, in use, causes a pressure differential between an interior space of the vehicle and the underbody of the vehicle.

3. A vehicle engine undercover assembly as claimed in claim 2 wherein the airflow outlet, in use, air cools an engine bay by drawing airflow through the engine bay while advantageously adding to the aerodynamic effect.

4. A vehicle engine undercover assembly as claimed in any preceding claim wherein each vortex generator has two leading surfaces.

5. A vehicle engine undercover assembly as claimed in claim 4 wherein the vortex generator is substantially pyramidal in shape.

6. A vehicle engine undercover assembly as claimed in any preceding claim wherein the undercover has multiple vortex generators placed in an evenlyspaced relationship across the undercover, the leading surface or surfaces of the vortex generators facing against the direction of airflow.

7. A vehicle engine undercover assembly as claimed in any preceding claim wherein ridge features run longitudinally from the front end of the undercover to the rear end of the undercover.

8. A vehicle engine undercover assembly as claimed in claim 7 wherein the spaces between adjoining ridge features form longitudinal channels longitudinally from the front end of the undercover to the rear end of the undercover.

9. A vehicle engine undercover assembly as claimed in preceding claim wherein the length of the vortex generator is twice its height.

10. A vehicle engine undercover assembly as claimed in preceding claim the

5 height of the vortex generator is between 15mm to 25 mm.

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