Patent Description:
A vehicle includes an engine which is associated with an engine idle speed after starting. At engine start, the engine is controlled according to a predefined attribute before settling at the idle speed. The attribute can be pre-set, prior to delivery to the end user, so as to achieve a desired effect on the end user.

One known attribute is known as a "sporty" attribute, or profile, which aims to maximise engine noise at engine start. This is achieved by including an overshoot in engine speed, known as an engine flare, prior to idle speed. In response to a start demand from a driver of the vehicle, the engine flares creating increased noise than would ordinarily be expected at engine start. Some drivers are keen on such a "sporty" attribute whilst other drivers may find the "sporty" attribute disconcerting.

In contrast, another known attribute is known as a "refined" attribute, or profile. The "refined" profile includes a lower magnitude of engine flare prior to idle than the "sporty" attribute. As a result, less engine noise is associated with the "refined" attribute compared with the "sporty" attribute. The "refined" attribute may be more appealing to certain consumers or certain vehicle models.

Known from document <CIT> or <CIT> are apparatuses comprising a user interface enabling an operator to manually select between a "sporty" attribute and a "refined" attribute.

It is an object of the present invention to further improve on the prior art.

According to an aspect of the present invention there is provided a control unit for a vehicle comprising: an input for detecting a start demand corresponding to a driver intent to drive the vehicle; a selection module arranged to, in response to detecting a start demand, automatically select between a first engine start profile and a second engine start profile in dependence on a monitored driving condition, wherein the monitored driving condition includes a time of day, and wherein the first engine start profile has a higher magnitude of engine speed overshoot (<NUM>) prior to idle than the second engine start profile and the second engine start profile has a supressed flare prior to idle speed; and a control module arranged to control an engine start attribute according to the selected engine start profile.

By predetermined driving condition is meant any condition at engine start-up which the vehicle is currently in and can be used to decide whether the first profile or the second profile is more appropriate for a current driver or use scenario. The selection module allows for an appropriate engine start profile to be selected depending on the driving conditions.

In an embodiment, the first profile may be a "sporty" profile and the second profile may be a "refined" profile.

In an embodiment, the first profile and/or the second profile may be customisable by an end user. In this way, the end user can customise the start profiles according to their personal tastes and preferences.

In an embodiment, the vehicle control unit may comprise a noise control module to control a supplementary noise source of the vehicle to accentuate the flare of the first engine start profile. Accentuating the effect of the flare using the supplementary noise source as opposed to further modifying the engine flare provides additional control and flexibility for the designer.

In an embodiment, the supplementary noise source may comprise an infotainment system comprising a speaker, the infotainment system may be arranged to emit additional noise in response to the first engine start profile being selected and may be arranged to emit anti-noise in response to the second engine start profile being selected. Additional noise allows for a louder engine start than may be possible by modifying the engine flare alone. Anti-noise allows for a quieter engine start than may be possible by modifying the engine flare alone. Either way, the impact on the end user is enhanced by the infotainment system being used in this way.

In an embodiment, the supplementary noise source may comprise an exhaust system. The exhaust system is associated with noise in use so accentuating or attenuating the noise from the exhaust system is an easy and reliable way in which to impact the end user at engine start.

In an embodiment, the noise control module may be arranged to configure an active exhaust valve of the exhaust system to direct a relatively high proportion of exhaust gas to flow through a suppressor in response to selecting the second engine start profile, and to direct a relatively low proportion of exhaust gas to flow through the suppressor in response to selecting the first engine start profile. The suppressor acts to suppress exhaust noise. A higher proportion of exhaust air flowing through the suppressor at engine start provides for a quieter exhaust system than lower proportion of exhaust air flowing through the suppressor at engine start.

In an embodiment, the noise control module may be arranged to configure one or more engine controllable elements to induce noise upstream through an induction system or downstream through an exhaust system, wherein said controllable elements are selected from the list of an engine intake valve, an engine exhaust valve, and a spark plug. In this way, sound effects such as "pops" and "bands" can be created which have a major impact on passers-by as well as vehicle occupants.

In an embodiment, the supplementary noise source may comprise an active intake system.

In an embodiment, the active intake system may comprise an active induction system.

In an embodiment, the active induction system may comprise a symposer for diverting induced airflow into two ducts each having different geometry to control the engine noise allowed to propagate from the engine. The supplementary noise source is thus indirectly linked to actual engine noise at engine start and so controlling the supplementary noise in this way is highly effective at accentuating or attenuating engine noise.

In an embodiment, the active intake system may comprise an active inlet manifold.

In an embodiment, the supplementary noise source comprises a tachometer. The tachometer can provide an artificial impression on the driver that, for instance, the engine speed perceived by the tachometer is different to the actual engine speed.

According to a further aspect of the present invention there is provided a vehicle including the aforementioned vehicle control unit.

According to a further aspect of the present invention there is provided a method of controlling a vehicle attribute comprising: monitoring a driving condition; detecting a start demand corresponding to a driver intent to drive the vehicle; automatically selecting, in response to detecting a start demand, between a first engine start profile and a second engine start profile in dependence on a monitored driving condition, the monitored driving condition including a time of day, wherein the first engine start profile has a higher magnitude of engine speed overshoot prior to idle than the second engine start profile and the second engine start profile has a suppressed flare prior to idle speed; and controlling an engine start attribute according to the selected engine start profile.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination that falls within the scope of the appended claims.

With reference to <FIG>, a vehicle <NUM>, such as a car or other such land vehicle, includes a drive system. Broadly speaking, the drive system includes an engine <NUM> for supplying power to two or more wheels <NUM>. The vehicle <NUM> also includes a plurality of sensors <NUM>, a start switch <NUM>, a vehicle control unit <NUM>, and engine control unit <NUM> and a supplementary noise source <NUM>.

The sensors are used for detecting various driving conditions. The driving conditions monitored by the sensors <NUM> include a time of day, a date, driver identification, vehicle location, ambient noise, throttle pedal actuation profile. Time of day can be monitored by an on-board clock. Likewise the date can be monitored in a similar way by monitoring a calendar of the on-board vehicle. Driver identification can be monitored by a position sensor which detects the locality of a driver identification chip held by a driver or other vehicle occupant. The ambient noise can be monitored by a sensor in the form of a microphone. Throttle pedal actuation profile can be monitored by a potentiometer monitoring for positional changes in the throttle pedal position in a car where the throttle pedal is used as a start switch.

The start switch <NUM> can be the throttle pedal, as described above. Alternatively, the start switch can be in the form of a dashboard mounted push button, or a key.

With reference to <FIG>, the vehicle control unit <NUM> includes an input <NUM>, a control module <NUM>, a selection module <NUM> and a noise control module <NUM>. The input <NUM> is connected to the sensors <NUM> and the start switch <NUM> to monitor for driving conditions and ignition demands respectively. Each of the aforementioned modules <NUM> - <NUM> are provided in the form of electronic data store on a non-volatile memory component of the control module <NUM>, which in this case is in the form of an on-board computer. The control module <NUM> also includes a processor to execute the electronic data store in the memory component in response to the input receiving the various driving conditions and ignition demands.

The control module <NUM> includes a look-up table including various engine start attributes. Amongst the attributes stored in the look-up table include a "sporty" profile and a "refined" profile. The characteristics of both of these profiles will be described in more detail below together with an explanation as to how they are realised. However, the look-up table may include customisable attributes which an end user can use to input a customised engine start profile according to their personal tastes and preferences.

The control module <NUM> feeds into the selection module <NUM>. The selection module <NUM> selects which engine start attribute to select in response to the input <NUM> detecting a start demand. The selection module <NUM> is able to select the appropriate attribute automatically based on the various vehicle conditions in order to make the selection. Alternatively, one of the sensors <NUM> can include a profile selector in the form of a dashboard switch or a touchscreen panel where a vehicle occupant is able to select manually which attribute is appropriate. In this way, the "sporty" profile is the default profile unless over-ridden by the demand for the "refined" profile.

This convention is most desirable, especially with regard to automatic attribute selection, so that a driver is not startled by an unexpected "sporty" profile being selected at ignition. Alternatively, in some but not necessarily all examples, the profile selected at the last vehicle ignition is selected as the default profile unless over-ridden by manual selection by the vehicle occupant.

In some but not necessarily all example of the present disclosure the correspondence between the various vehicle conditions and an engine start attribute that enables the selection module <NUM> to automatically select the appropriate attribute based on the various vehicle conditions is customisable by the end user. For example, the end user may program a time of day range (e.g., <NUM> pm to <NUM> am) that corresponds to an engine start attribute.

Once the profile has been selected, the engine control unit <NUM> is configured to control various controllable parts of the engine <NUM> to operate according to the selected profile. The controllable parts of particular interest include a throttle plate, air intake valves, and exhaust valves of the cylinders, as well as fuel and injection angle. The throttle plate is located upstream of the engine and controls the flow rate of air entering the engine. A throttle plate orientation allowing a large flow rate of air to pass is associated with a high engine speed, rpm. A throttle plate orientation allowing a lower flow rate of air to pass is associated with a lower engine speed, rpm.

The intake valves are timed to open at the start of an intake stroke and close at the end of the intake stroke/start of the compression stroke. The exhaust valves are timed to open at the start of an exhaust stroke and close at the end of the exhaust stroke/start of the following intake stroke. However the timings of the intake and exhaust valves opening and closing can be made variable according to a variable valve lift control protocol as will be described in more detail below.

With reference to <FIG>, the "sporty" profile <NUM> and the "refined" profile <NUM> are graphically presented in the form of engine speed (rpm) against time (s). In this way, the "sporty" profile <NUM> is a first profile and the "refined" profile <NUM> is a second profile. However, there may be more than two profiles which are selectable by a driver.

The "sporty" profile <NUM> includes an overshoot <NUM> in engine speed prior to idle speed <NUM>. The peak speed of the overshoot <NUM> has a magnitude of four times greater than the idle speed <NUM>. The idle speed <NUM> is approximately 800rpm. The overshoot <NUM> is known as engine flare. An overshoot in engine speed is realised by opening the throttle plate transiently to a far greater angle of inclination than is required for idle speed <NUM> immediately followed by a change in throttle plate angle to one suitable for producing the idle speed <NUM>. The engine flare can be calibrated by optimising the throttle plate orientation. The intake and exhaust valves can also be used to calibrate the profile of the engine flare <NUM>.

In some but not necessarily all example of the present disclosure the rate at which the engine speed is reduced from the peak speed of the overshoot <NUM> to the idle speed <NUM> can be increased by switching on one or more ancillary loads such as, for example, an air conditioning system, a radio, windshield wipers, headlights.

The "refined" profile <NUM> includes no overshoot or engine flare and as such the engine flare <NUM> of the "sporty" profile <NUM> is greater than the engine flare of the "refined" profile. In fact, any flare of the "refined" profile has been suppressed to an extent that there is no flare present. The lower engine flare is achieved again by tuning the throttle plate orientation and movement. The intake and exhaust valves of the cylinders may also by calibrated in order to eliminate the engine flare.

The selection module <NUM> is also connected to the noise control module <NUM>. The noise control module <NUM> is connected to a supplementary noise source <NUM> to control the noise therefrom. It is envisaged that the term "noise" encompasses volume, tone, coarseness, and pitch, as well as the degree of throatiness and raucousness. The supplementary noise source <NUM> is used to accentuate further the noise corresponding to "sporty" profile of the engine. Specifically, the engine flare noise of the "sporty" profile can be accentuated in this way. The supplementary noise source <NUM> can be any of a number of ancillary systems existing on the vehicle <NUM>. In this way, the supplementary noise source <NUM> may include an infotainment system (<FIG>), an active exhaust system (<FIG>), and an active intake system (<FIG>). The supplementary noise systems are described in more detail below.

With reference to <FIG>, one possible supplementary noise source comprises an infotainment system <NUM>. The infotainment system <NUM> includes a speaker <NUM>. Where the "sporty" profile is selected, the infotainment system <NUM> is configured, by the vehicle control unit <NUM>, to emit sound <NUM>. The sound <NUM> produced by the speaker <NUM> can be of various forms including "pops" and "bangs" to replicate those noises sometimes emitted from the exhaust system during acceleration. Alternatively or additionally, the sound <NUM> can include a recording of engine revolutions or other engine noise enhancements indicating refined or sporty.

With reference to <FIG>, another possible supplementary noise source comprises an active exhaust system <NUM>. The active exhaust system <NUM> includes an exhaust pipe <NUM>. The exhaust pipe <NUM> is used to transfer exhaust gas <NUM> from the engine <NUM> (<FIG>) to the exterior environment of the vehicle. The active exhaust system <NUM> includes an active exhaust valve <NUM> situated within the exhaust pipe <NUM>. Downstream of the active exhaust valve <NUM>, the exhaust pipe <NUM> is bifurcated. The active exhaust system <NUM> also includes a suppressor <NUM> in one branch of the bifurcated portion of the exhaust pipe <NUM>. The suppressor <NUM> is known in the art and is thus not described in any great detail here. A noisy branch <NUM> is provided by the branch not having the suppressor <NUM> since the exhaust pipe amplifies reverberations caused by the exhaust gas <NUM>. A quiet branch <NUM> is provided by the branch having the suppressor <NUM> since the suppressor <NUM> attenuates noise resulting from reverberations caused by the exhaust air <NUM>.

The active exhaust valve <NUM> is a ball valve having a normal position arranged to direct a relatively high proportion of exhaust gas <NUM> down the noisy branch <NUM>. The active exhaust valve <NUM> also has a silenced position arranged to direct a relatively high proportion of exhaust gas <NUM> down the quiet branch <NUM> instead of the noisy branch <NUM>. The active exhaust valve <NUM> is configured by the vehicle control unit <NUM> to transition between the normal and noisy positions depending on whether the "sporty" or the "refined" profile has been selected.

In addition, operation of an engine intake valve, engine exhaust valve, and valve lift can be controlled to induce noise away from the engine. In particular, fixed valve operation, variable valve timing and valve lift can be used to affect the transmission of exhaust noise back through an induction system of the vehicle. Also, opening the engine exhaust valve early creates combustion whilst the exhaust valve is already open resulting in combustion taking place within the exhaust pipe <NUM>. When combined with a late spark, the combustion within the exhaust pipe <NUM> results in various acoustic effects such as "pops" and "bangs". These acoustic effects can be used to exaggerate the flare of the "sporty" profile. Conversely, the opposite of the above will result in a "refined" profile.

With reference to <FIG>, the supplementary noise source comprises an active intake system <NUM>. The active intake system <NUM> includes an active induction system <NUM> and an active inlet manifold <NUM>.

The active induction system <NUM> includes a primary pipe <NUM> extending downstream from an air filter <NUM>. The active induction system <NUM> also includes a symposer <NUM> downstream of the primary pipe <NUM>. The symposer <NUM> includes a relatively long duct <NUM> and a relatively short duct <NUM> in direct fluid communication with the primary pipe <NUM>. The symposer <NUM> also includes an active intake valve <NUM> positioned downstream from both the long and short ducts <NUM>, <NUM> at entry to the active inlet manifold <NUM>. The active intake valve <NUM> is again a ball valve being controllable by the noise control module <NUM>. In a noisy configuration, the active intake valve <NUM> directs intake air through the relatively long duct <NUM>. The relatively long duct allows a relatively high degree of engine noise to propagate upstream when the cylinder inlet valves and the throttle plate open. In a quiet configuration, the active intake valve <NUM> directs intake air through the relatively short duct <NUM>. The relatively short duct <NUM> allows a lower amount of engine noise to propagate upstream than the relatively long duct <NUM>, due to its increased length of the long duct <NUM>. It is possible to control upstream engine noise propagation by including ducts of different diameters as an alternative or in addition to the change in length between the ducts. Other configurations are also possible provided that there is a relatively noise duct and a relatively quiet duct.

Furthermore, a tachometer can be recalibrated to artificially give the impression of varying amounts of engine flare in addition to the aforementioned noise systems.

The vehicle control system is best described with reference to various scenarios of operation.

In one scenario, a enthusiastic driver is intending to the drive the vehicle <NUM> (<FIG>). The vehicle <NUM> is located in a built up area in the middle of the day where there is copious ambient noise. The enthusiastic driver selects manually, using a touch screen on the dashboard, the "sporty" profile. The selection module determines that the "sporty" profile is appropriate for use since an engine flare will not cause unsatisfactory noise pollution nor unduly startle neither passers-by nor the driver. The driver presses the start switch <NUM>. The engine control unit <NUM> configures the engine to flare <NUM> prior to idle speed <NUM> (<FIG>).

In parallel to the engine <NUM> operating in accordance with the "sporty" profile, the noise control unit <NUM> configures one or more of the supplementary noise sources <NUM> to accentuate the noise of the engine flare. In particular, the infotainment system <NUM> is configured to produce acoustic effects simulating mechanical noises relating to the engine at engine start. Specifically, the infotainment system emits sound <NUM> simulating "pops" and "bangs" together with a simulated engine flare. Additionally, the active exhaust system <NUM> is configured, by the noise control module <NUM>, to set the active exhaust valve <NUM> to a noisy configuration and direct a relatively large proportion of exhaust gas <NUM> down the noisy branch <NUM> and not down the suppressor <NUM>. To create further noise, the engine valves and spark timings are adjusted to causes acoustic effects, such as "pops" and "bangs" within the exhaust pipe <NUM>.

The active intake system <NUM> is also set to produce noise by the noise control module <NUM>. Specifically, the active intake valve <NUM> is configured to allow the intake air to flow through the long duct <NUM> and blocks air from flowing through the short duct <NUM>. In this way, engine noise is allowed to propagate upstream.

In another scenario, the enthusiastic driver again intends to drive the vehicle <NUM> (<FIG>). This time, the vehicle is about to be driven at night in a built up area with little ambient noise. The selection module <NUM> determines that the engine flare <NUM> of the "sporty" profile <NUM> (<FIG>) is not appropriate and prevents the enthusiastic driver from selecting it. Instead, the "sporty" profile is automatically over-ridden by the selection module <NUM>. At engine start, no engine flare is present and the engine speed transitions directly to idle speed <NUM> (<FIG>).

The noise control module <NUM> configures the infotainment system <NUM> to emit anti-noise to counteract the engine noise (<FIG>). In addition, active exhaust valve <NUM> is configured to direct the exhaust air <NUM> through the suppressor <NUM> (<FIG>). Also, the engine inlet valves are configured to open in concert with the start of the intake stroke meaning that a fuel to air ratio is optimised and combustion thus takes place entirely within the cylinders as opposed to occurring briefly within the exhaust pipe. Finally, the symposer <NUM> is configured such that the active intake valve <NUM> directs the intake air through the short duct <NUM> as opposed to the long duct <NUM> so as to reduce the engine noise propagating upstream from the engine <NUM> (<FIG>).

Claim 1:
A control unit (<NUM>) for a vehicle comprising:
an input (<NUM>) for detecting a start demand corresponding to a driver intent to drive the vehicle;
a selection module (<NUM>) arranged to, in response to detecting a start demand, automatically select between a first engine start profile (<NUM>) and a second engine start profile (<NUM>) in dependence on a monitored driving condition, wherein the monitored driving condition includes a time of day, and wherein the first engine start profile (<NUM>) has a higher magnitude of engine speed overshoot (<NUM>) prior to idle than the second engine start profile (<NUM>) and the second engine start profile has a supressed flare prior to idle speed (<NUM>); and
a control module (<NUM>) arranged to control an engine start attribute according to the selected engine start profile.