WO2011007006A1

WO2011007006A1 - Vehicle battery charging apparatus

Info

Publication number: WO2011007006A1
Application number: PCT/EP2010/060361
Authority: WO
Inventors: Benno Pichlmaier
Original assignee: Agco Gmbh; Technische Universitat München
Priority date: 2009-07-17
Filing date: 2010-07-16
Publication date: 2011-01-20
Also published as: GB0912452D0

Abstract

Battery charging apparatus comprising a thermoelectric module (71) is provided. The module (73) is affixed to a relatively hot surface (72) of a vehicle so as to exploit the heat energy expelled therefrom Electrical energy is generated from a temperature gradient which occurs between said surface and the environment, wherein the electrical energy is used to charge a battery (36) located upon the vehicle.

Description

DESCRIPTION

VEHICLE BATTERY CHARGING APPAR VTLS

The invention relates tυ apparatus for charging a battery on a vehicle especially a tractor in particular, but not exclusively so, the invention relates the charging of batteries which are fixed relative to vehicle wheels.

The inflation pressure of vehicle tyres is known to be a contributory factor in the tyre wear, the grip provided by the tyre and the fuel consumption of the vehicle By reducing the pressure of the tyre the contact surface with the ground is increased thereby, on soft soil, improving the grip allowing a greater power to be transmitted between the vehicle and the ground and reducing harmful soil compaction At the same time rolling resistance and slip can be reduced increasing tractive efficiency.

However an increase in contact surface results in an increase in t>re wear and, as is particularly apparent on haid surfaces at speed, an increase in fuel consumption. Therefore it is recognised that optimum performance of the vehicle is achiev ed with different tyre inflation pressures for different operating conditions This has fed to the development of automatic inflation and deflation arrangements which allow the tyre inflation pressure to be changed during operation to optimise the driving characteristics described above.

German Utility Model DE 29718420 Ul describes a tyre pressure control system wherein a wheel comprises an integrated compressed air reservoir located on the ran and surrounded by the tyre. Air is transferred from the reservoir to the tyre by means of a valve so as to inflate the tyre when required. The tyre is deflated via the same valve by transferring air to the environment. A control device is also located between the πni and the tyre and serves to control the valve means thereby inflating and deflating the tyre The tyre pressure is maintained at a set point by the control device automatically activating the valve means in response to a measured distance between the πm and the tyre A battery located on the wheel powers the control device.

The battery requires regular replacement or recharging to keep the system operational. This is time consuming and expensive

It is therefore an object of the invention to provide battery charging apparatus which is suitable for charging a battery on a vehicle and has low maintenance requirements. In aecυidance w ith the invention thcic is prov ided battery charging apparatus comprising a thermoelectric module affixed to the surface of a v ehicle, the module aπanged to generate electrical enesgv tiom a temperatuie gradient occurring between said surface and the ens ironment, w herein the electrical tnergv is used to ehαtge a batter> located upon the

The generation of electrical energv by thermoelecttic effects is known and desciibcd at website

tor example The inventors have recognzied that heat energy normally expelled by a vehicle during opeiation can be exploited to generate electricity to chaige an on-board battery Advantageously, such apparatus requires little, it no, maintenance

In a preferred arrangement the thermoelectric module is atfixed to a wheel mounting boss attached to a driven axle, the boss containing oil In tractor axles, the oil which ser\es to lubricate moving parts concealed by the boss, to pically operates at temperatures in the range 80- 120ºC By placing one or more thermoelectric modules around the outer circumference oi the boss, the heat energy ot the oil is transferred to the module through the surface of the boss A thermal gradient is set up across the module between the relatively hot surface ot the boss and the module surface exposed to the cooler ambient air

The modules disposed around a boss are preferably connected in seiies by wires Advantageously, this minimises the number of wires which connect the modules to the battery The vvites are preferably housed m ducts formed w ithin the boss so as to avoid exposed wires which could suffer from damage caused by falling objects such as soil and stones

The apparatus may comprise a collar which fits over an outside surface of the boss, the collar hav mg a plurality of slots each for receiving a respective module so that heat energy can transfer from the outside surface ot the boss to an innermost surface of each module The collar may be formed ot a material which allow s heat shrinking to be used to securely fix the collar to the boss A secure fit ensures efficient heat transfer between the boss surface and the modules

By providing the battery charging apparatus on the boss, the invention lends itself, well to the charging ot a battery which is fixed relative to a wheel Advantageously, because the boss rotates with tht wheeel. no rotary transfer connection is lequπed to transfer the energy to the battery or capacitor

I he inv ention is paiticularly advantageous when applied to a t tat tor which typically includes lubricating oil at high iuvipuatures dui sng operation

The thermoelectric module may be at fixed to other relativ ely hot components to exploit the expelled heat energy such as an exhaust pipe 01 engine easting

Further advantages ot the invention will become apparent trom the following desu iption ot specific embodiments with reference to the drawings in which :-

Figiite I is a schematic diagram ot a tyre inflation pressute control system f igure 2 is an end on v iew of a wheel-mounting boss ot battery charging apparatus m accordance with one embodiment of the invention, figure ^ is a perspectiv e view ot the wheel-mounting boss of Figure 2

Figure 4 is an exploded v iew of the wheel mounting boss ot Figure 2 showing components ot a thermoelectric charging apparatus,

Figuie 5 is a side view of the wheel-mounting boss ot Figure 2, and

Figuie 6 is a sectional view taken along the line A-A of Figure 2

Referring to Figuie 1 a tractor comprises a chassis designated generally at 10 and a wheel designated geneudly at 12 It should be undet stood that Figuie 1 is highly schematic and features located within dashed box 10 aie located anywhere on the tiactor whereas those katuies w ithin dashed box 12 are integrated w ith the wheel and rotate therew ith Furthermore the tractor comprises at least four wheels wherein two or maybe tour have the same construction as described below with ietercnce to wheel 12

The wheel 12 comprises a generally cylindrical rim (not shown) upon which a tubeless tvre is mounted A toroidal an reservoir 14 formed of reinforced rubber is disposed on the wheel run within the volume defined by the tyre Therefore the air reservoir forms an inner chamber 14 of pressurised air and the tyre forms an outer chamber 16 The volume of the air reservoir 14 is substantial fixed due to the reinforcement of the rubber material Iheiefoie detotmatioπ ot the material between the air teservoir and the tγic volume does not occur when significant presume diffeienees arise between the chambers 14, 16

The volume υt air reservoir 14 is in the region ol 320 lures and the inflatable volume of tyre 16 is in the region of 490 litres The maximum operating piessiirc ot the an reservoir is aiound 6 bar whereas the opeiating pressure ot the tyre 16 topically vanes between 0 S and 2 bar

It should be appreciated that tor trailers (eg muck ttatlers) this maximum tyte pressure is around 4 bar and that different vehicles require different inflation pressures and have different tyre and reservoir volumes

The system comprises a decant valve 18 and a deflate vatve 20 each of which is a pilot controlled check valve Decant valve 18 is located in a fluid tianster fine between the air reservoir 14 and tyre !b Deflate valve 20 ts located m a fluid transfer line between the tyre 16 and the env uonment

Each check valve 18, 20 has associated therewith a piezoelectric control valve A first piezoelectric valve 22 contiols the delivery of a piiot pressure taken from air reservoir 14 to decant valve 18 via pilot lme 24 A second piezoelectric control v

ales 26 controls the delivery of a pilot pressure also from air reservoir 14 to the deflate valve 20 via pilot line 28 Each piezoelectric valve 22, 26 is activated by a vaive control unit 30 employing electrical signals sent via respective lines 31,32

The significantly larger pressure of air reservoir 14 keeps decant v

alve 18 in a closed position in normal operation By activation of piezoelectric valve 22 a ptlot pressuie opens decant valve 18 and allows air to transfer into tyre volume 16 thus increasing the pressure therein

During normal operation the piessure within tyre !6 maintains deflate valve 20 in the closed position Upon activation of piezoelectric valve 26 a pilot pressure fotccs deflate valve into an open position thereby allowing air to exit tyre volume 16 thus causing a reduction in the pressure thereof

Each chamber 14,16 comprises a respective pressure relief valve 34a.34b which can be preset to relieve the pressure within the respective chamber when it exceeds a predetermined value F urthermore each chamber 14, 1 6 has associated thci ew ith a pressure sensor 35a, 35b each w ith a respectiv e wired link to valve control unit 30 Each pressure sensor 35a 35b senses the pressure m the associated volume ind transmits this, information to the valv e control unit 30

A rechargeable battery 36 is arranged within the wheel assembly 12 so as- to pow er the valve control unit 30 However, in an alternative arrangement, the battet y may be replaced w ith a capacitor which can deliver a high current and be charged ov er a short period Apparatus, to chai ge the battery 36 w ill be described in more detail below

The pressure control system turther comprises a controller 40 located on the tractor chassis 10 The conti oller 40 is in w ireless and bidirectional communication with

contiol unit 30 in accordance w ith the invention by a wireless link The controller 40 is also in communication with a tractor management system 50 which serv es to monitor and control various operating parameters of the tractor such as speed, w heel slip and transmission ratio for example

An air pressure source 52 is provided by an an pump which is located on the tractor The air source 52 can supply pressurised air via an electric valve 54 and a iotary transfet arrangement ^6 and check valve 58 to the reserv oir 14 The v alve 54 is controlled via a wired link by the controller 40 The iotary transfer arrangement 56 is of a known construction such as that disclosed tn US-6,439.044 by way ot example only This allows pressurised air to be transferred from the chassis 10 to the rotating wheel assembly 12

An example sequence ot operation will now be described with reference to Figure 1 The pressures within reserv oir 14 and tyre 16 are sensed by pressure sensors 35a, 35b and communicated to tractor management system 50 via valve control unit 30, wireless link 42 and controller 40 This information may be displayed to the driv er Commands from the driver arc entci ed into the tractoi management system 50 via a usei interface (not shown) C ommands are then communicated to controller 40 w hich then passes the command to valve control unit 30 via wireless link 42

The target pressuie is stored locally on the wheel by the valve control unit 30 This v alue is updated by the controller 40 v ia the w ueless link periodically and or w hen a change demand occurs

In the case of the sensed pressure being below the target pressure, v alve control unit 30 activ ates ρiezoe!ectric valve 26 by an electric signal sent by line 32 Piezoelectric v alve 26 is activated ior a predetci mmed duration ot say 5 seconds which causes deflate valve 20 to open therebv rcduung the pressure in tyre 16 The pressuie sensed in tyre 1 6 is then eompai ed Io the commanded pressure and, if further deflation is required, piezoelectric valve 26 is activated tor another period

It should be undei stood that the duration at whieh the piezoelectric valves 22,26 are activ ated may be determined by an algorithm w hich takes into account the existing pressure in chambers 14.16 and the target pressure of tyre 16 Alternatively, real time adjustment may be employed to set the inflation pressuie at the desired value by constant measuring ot the pressure in combination w ith control ot the decant process

Din ing operation v alve control unit 30 continually monitors the pressure within tyre 16 and compares st to the taiget pressure and activ ate the piezoelecti ic valves 22 26 accordingly

The above described control and monttotmg of the inflation pressure is executed on a local basis at the w heel by the valve control unit 30 By onlv updating the target pressure w hen a change is tequired (either demanded manually by the driver oi automatically via the management system 50) the number ot messages passing over the w ireless link 42 is minimised Advantageously this reduces the energy consumption ot the battery 36 and av oids unreliable control caused by discontinuities in the wireless connection 42

It is env isaged, however, that control and monitoring of the inflation pressure may be done instead by the controller 40 v ia wireless link 42 wherein valve control unit 30 simply serves to pass on the sensed parameters and control the valves 22, 26 as demanded The target inflation pressure in this case is stored by the controller 40 or management system 50

In the case where the sensed pressure w ithin air reserv oir 14 di ops below a piedetei mined threshold, vales control unit 30 commands a top-up action to controller 40 via wireless link 42 Such a command triggers activ ation of piezoelectric va

lve 54 wbsch transfers air under pressure from air source 52 to air i eserv oir 14 until the target pressure is obtained

In accordance w ith the invention, the system includes apparatus to charge the battery usmg thermoelectric energy created at the tempeiature gradient between relativ ely hot oil in the rear axle and the cool air ot the env ironment With reterence to Figures 2 to 6, a wheel boss 70 ot a dπven axle (not shown) is prov ided with bolts 71 to fix thereupon the rim and wheel 12 (not show n m Figs 2 to 6) The wheel boss 70 conceals a planetary gear set (not shown) to reduce the axle speed down to wheel speed and contains oil for lubrication thereot A toroidal shaped earrier part 72 formed of steel is, fixed to the cneumterctiee of the wheel boss 70 by heat shi inking tor example

Eight thermoelectric modules 73 are glued inside slots 72a of the carrier part 72 These slots 72a are also connected to a wiring duet 72b connecting all slots 72a Inside the wiring duct 72b, each harness 73a of each thermoelectric module 73 is installed and connected in series and then guided to the battery 36 By installing the w iring harness inside the duct 72b, the wiring harness is protected in rough operating env ironments from tailing objects such as stones, etc

The thermoelectric effect is a known physical phenomenon and is described at website page to which reference is invited.

The oil ib prov ided tor lubrication pmposes for the planetary gear within the wheel boss During operation, the oil w ithin the sump reaches temperatures in the range of 80-120ºC. In turn, this heats the wheel boss to a similar temperature due to the conductive nature of the boss material If the ambient temperature is considered to be about 30ºC, a difference of minimum 50 Kelvin can be exploited to generate electrical energy by using the thermoelectric effect

As both surfaces of the housing part 70a and the inner side of the carrier part 72 are in contact, heat is transferred across the interlace therebetween The wall thickness at the base of the slot 72a of the carrier part 72 is very thin This atlows heat to be transferred effectively to the inner surface 73b ot the thermoelectric modules 73 thus creating a thermal gradient across the thickness of each module 73

The wheel boss 70 rotates with the wheel and so the means for electuary generation does not require a rotary transfer connection Therefore, the temperature gradient between the hot oil and cool env ironment is exploited to continuously charge battery 36

Although the above-described embodiment includes the thermoelectric modules attached to a wheel boss, it is envisaged that other hot surfaces of a tractor could instead, or additionally, be exploited For example, such modules can be affixed to the surface of an exhaust pipe or an engine casting without dev iating from the scope of the invention It will be appreciated also, that the apparatus in accordance with the invention can be employed to charge any battery (or equivalent) w hich is located on the vehicle, u hethet the battery is fi\ed relative to a rotating u heel or not

From reading the present diselosuie, other modification w stl be apparent to persons skilled tn the ad Such modifications mav in\ol\ e other features which die already known in the field of battery charging apparatus and component parts thereto! e and which may be used instead of or in addition to features already described heiein

Claims

CL AIMS

1 Battery charging apparatus comprising a thermoelectric module affixed to the surface of a vehicle, the module ananged to generate electrical energy from a temperature giadient occun mg between said sui tace and the cnvuonment, wherein the electrical energy is used to charge a batten, located upon the vehicle

2 Apparatus according to Claim 1 , wherein the thermoelectric module is affixed to a wheel mounting boss attached to a driven axle, the boss containing oil

3 Apparatus according to Claim 2, comprising a plurality of thermoelectπc modules affixed to a surface around the outer circumference of the wheel boss

4 Apparatus according to C laim 3, wherein the modules aic connected in series by w ires

5 Apparatus according to Claim 4, wherein the wires are housed in ducts formed within the boss

6 Apparatus according to any one of C laims 3, 4 or 5, comprising a collar which fits over an outside surface of the boss, the collar having a plurality of slots each for recei\ tng a respective module so that beat energy can transfer from the outside surface ot the boss to an innermost surface of each module

7 Apparatus according to Claim 6, wherein the collar is formed ot steel

8 Apparatus according to Claim 1, w herein the module is atfixed to an exhaust pipe

9 Apparatus according to Claim 1 wherein the module is affixed to an engine casting

10 A tractor comprising apparatus according to any preceding claim

1 1 A tyre inflation pressure control system comprising apparatus according to any one ot C laims 2 to 7, wherein the battery is fixed relative to a wheel which is attached to the boss

12 Battery charging apparatus constructed and arranged substantially as hereinbefore described with reference to and as shown in Figures 5 to 9