Cleaning system for a vehicle component

Abstract

A cleaning system for removal of contaminants from a surface of a vehicle component exposed to a gas or fluid flow, the cleaning system comprising: an excitation device adapted to be attached to the vehicle component in the vicinity of the surface exposed to contaminants, wherein the excitation device is configured to cause the surface to mechanically vibrate by transferring a vibrational excitation to the surface; wherein the frequency of the vibrational excitation is controllable to be based on the configuration of the vehicle component as well as other modelled/measured parameters.

Claims

1. A cleaning system for removal of contaminants from a surface of a lambda probe, temperature probe, or heat exchanger exposed to a gas or fluid flow, the cleaning system comprising: an excitation device adapted to be attached to the vehicle component in the vicinity of the surface exposed to contaminants, wherein the excitation device is configured to cause the surface to mechanically vibrate by transferring a vibrational excitation to the surface, wherein the excitation device is arrangeable isolated from the gas or fluid flow; wherein the frequency of the vibrational excitation is controllable to be based on the configuration of the vehicle component, wherein the frequency of the vibrational excitation is swept through a frequency range comprising a natural frequency of the lambda probe, temperature probe, or heat exchanger.

2. The cleaning system according to claim 1, comprising a control unit configured to control the frequency of the vibrational excitation.

3. The cleaning system according to claim 2, wherein the control unit is configured to sweep the frequency of the vibrational excitation through the frequency range comprising the natural frequency of the lambda probe, temperature probe, or heat exchanger.

4. The cleaning system according to claim 1, wherein the excitation device comprises a rotating unbalance device.

5. The cleaning system according to claim 4, wherein the rotating unbalance device comprises an electric motor, wherein the electric motor is configured to cause a rotation member to rotate about an axis of rotation, wherein the axis of rotation is off-center from the center of mass of the rotation member.

6. The cleaning system according to claim 1, wherein the excitation device comprises an ultra-sound generator.

7. The cleaning system according to claim 1, wherein the excitation device comprises a piezoelectric component or a vibrational solenoid, and a power source configured to provide an excitation voltage signal to the piezoelectric component or the vibrational solenoid to cause the piezoelectric component or the vibrational solenoid to vibrate.

8. The cleaning system according to claim 1, wherein the excitation device comprises a linear resonant actuator.

9. The cleaning system according to claim 1, wherein the excitation device is an add-on device adapted to be retrofitted on pre-mounted vehicle components.

10. The cleaning system according to claim 1, wherein the excitation device is comprised of an active damper for mechanically damping a power train of the vehicle.

11. The cleaning system according to claim 2, wherein the control unit is configured to: receive an event signal indicative of internal or external vehicle events, and trigger the excitation device to provide the vibrational excitation in response to receiving the event signal.

12. The cleaning system according to claim 2, wherein the control unit is configured to detect that the vehicle component is contaminated, wherein the control unit is configured to cause the excitation device to provide the vibrational excitation until a pre-determined cleansing level is reached.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing example embodiments of the invention, wherein:

(2) FIG. 1 conceptually illustrates application of embodiments of the invention;

(3) FIG. 2 schematically illustrates an exhaust aftertreatment system where a cleaning system may be implemented according to exemplary embodiments;

(4) FIG. 3 schematically illustrates an excitation device attached to a lambda probe;

(5) FIG. 4 conceptually illustrates an air intake and exhaust outlet system of a combustion engine, where cleaning system elements may be implemented according to exemplary embodiments;

(6) FIG. 5 is a box diagram of a cleaning system according to example embodiments;

(7) FIG. 6a-b conceptually illustrates an example excitation device;

(8) FIG. 7 conceptually illustrates an example excitation device;

(9) FIG. 8 is a box diagram of a cleaning system according to example embodiments;

(10) FIG. 9 schematically illustrates a sub-frame having thereon an active damper;

(11) FIG. 10 is a flow-chart of method steps according to embodiments of the invention; and

(12) FIG. 11 is a flow-chart of method steps according to embodiments of the invention.

DESCRIPTION OF EMBODIMENTS

(13) In the present detailed description, various embodiments of the cleaning system according to the present invention are mainly described with reference to sensors in an aftertreatment system or in exhaust recirculation devices. However, the present invention is equally well applicable to other vehicle components such as components of heat exchangers and mixture preparation systems of vehicles.

(14) A vehicle in accordance with the present inventive concept include any type of vehicle such as e.g. cars, busses, trucks, boats, ships, trains, covered as any ground-, sea-, or air-vehicles, etc. Thus, this invention may generally be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person. Like reference characters refer to like elements throughout.

(15) FIG. 1 conceptually illustrates a vehicle in the form of a car 1. The car 1 comprises a combustion engine, such as a diesel engine 108, which produces exhaust effluents. The car further comprises an exhaust aftertreatment system for reducing the emissions of e.g. nitrogen oxides, from the combustion, primarily emitted via the tail pipe 105. The aftertreatment system comprises a mixing section 104, which receives exhaust gas from the engine 108, and a selective catalytic reduction device 112 (SCR-device) arranged downstream of the mixing section 104. Optionally, a particulate filter 103 is arranged between the mixing section 104 and the engine 108.

(16) There is further a tank 107 serving as a reservoir of a liquid reductant provided to the mixing section 104. The liquid reductant is often a urea solution provided to the exhaust gas in controlled amounts for increasing the efficiency of the SCR-device. However, dosing at low temperatures leads to inability to evaporate the liquid reductant and thereby to an increased risk of deposit build-up on vehicle components arranged in the exhaust gas flow.

(17) FIG. 2 schematically illustrates an exhaust aftertreatment system 100 in which embodiments of the cleaning system may be arranged. As described with reference to FIG. 1, an engine 108 produces exhaust gases which is received by a mixing section 104 of the aftertreatment system 100 through an inlet 106. Optionally, a particulate filter 103 is arranged between the mixing section 104 and the engine 108.

(18) The system 100 further comprises an injection unit 101 for providing a liquid reductant to a mixing compartment 110 of the mixing section 104.

(19) Furthermore, a sensor in the form of an oxygen sensor 202 is arranged in the exhaust gas flow up-stream of the catalytic converter, i.e. the SCR-device 112. Such oxygen sensor 202 is often called a lambda probe and is configured to measure the proportion of oxygen in the exhaust gas flow. With the measured oxygen levels, it is possible for a vehicle control unit to determine the amount of fuel required for complete combustion in the engine. The lambda probe may however be contaminated by soot in the exhaust gas, which may affect its performance. Therefore a cleaning system (not shown, see FIG. 3), in accordance with embodiments of the invention, is arranged for removal of contaminants from a surface of the vehicle component 202, here in the form of a lambda probe 202. This will next be described in more detail with reference to FIG. 3.

(20) FIG. 3 schematically illustrates a perspective cross-section part of the SCR-device 112 and the inlet 114 shown in FIG. 2. Furthermore, FIG. 3 shows the vehicle component in the form of the lambda probe 202 shown in FIG. 2 arranged up-stream of the SCR-device 112.

(21) The sensor surface 204 of the lambda probe 202 is exposed to the contaminated exhaust effluent flow and is thus susceptible to soot deposits. A cleaning system 200 comprising an excitation device 206 is attached to the lambda probe 202 outside of the gas flow. Thus, the excitation device 206 is not exposed to the internal gas flow in the exhaust aftertreatment system.

(22) The excitation device 206 is configured to cause the contaminated surface 204 to mechanically vibrate. For this, the excitation device 206 is adapted to transfer a vibrational excitation to the surface 204. The excitation device 206 is mechanically fixated to the lambda probe 202 such that the excitation device 206 may transfer a mechanical vibration via the body of the lambda probe 202 to the surface 204.

(23) The excitation device 206 is communicatively connected to a control unit (not shown), which controls the frequency of the vibration via electrical command signals. The frequency of the excitation is selected based on the configuration of the vehicle component. In this example case, the frequency of the excitation is selected based on the configuration of the lambda probe 202. Preferably, the frequency of the vibrational excitation comprises the natural frequency of the casing of the lambda probe 202. The control unit may be a comprised in the cleaning system 200, alternatively the control unit may be a vehicle control unit, e.g. an ECU of the vehicle connected to the excitation device 206. When the control unit is comprised in the cleaning system 200 it advantageously functions as a stand-alone device. In such case, the control unit may be arranged in the same housing as the excitation device.

(24) Furthermore, the excitation device 206 is only conceptually shown in FIG. 3, and the dimensions and appearance may thus differ from the conceptual illustration. For example, the excitation device 206 may be enclosed in a housing.

(25) In FIG. 3 the cleansing system is exemplified as cleaning a lambda probe. However, various other vehicle components may be cleaned using a cleaning system in accordance with embodiments of the invention. Some examples include: components of exhaust gas recirculation systems such as valves and cooler surfaces, oil separator components, oil cooler components, turbo system components, other sensor surfaces, cylinder head components, etc.

(26) Accordingly, a cleaning system according to embodiments of the invention may be arranged to remove contaminants from various vehicle components. FIG. 4 exemplifies some example vehicle components.

(27) FIG. 4 conceptually illustrates an air intake and exhaust outlet system of a combustion engine and exemplary locations for an excitation device 302 according to some possible implementations for embodiments.

(28) In detail, FIG. 4 schematically illustrates an intake air cooler 404 adapted to receive air from the outside environment and an air intake gas flow regulator 405 configured to regulate the gas flow into the intake air cooler 404 and to measure the gas flow into the intake air cooler 404.

(29) Further, a temperature sensor 406 is arranged in the air flow to measure the temperature of the air downstream of the air cooler 404. This may be advantageous for ensuring that too high temperature fluctuations in the intake do not occur. Such temperature sensors 406, air coolers 404, and regulators 405 are susceptible to particle deposits and may thus be in need of cleaning. Thus, an excitation device 302 may advantageously be used for cleaning these vehicle components.

(30) A cylinder head 407 is arranged to seal a cylinder volume 402, where the piston 409 operates during combustion of the fuel. Air mixed with recirculated exhaust gas is allowed into the cylinder volume 402 via an air intake control valve 408 arranged in the cylinder head 407. A cam 410 of a camshaft is adapted to cause the spring loaded valve to open and close via the rotation of a camshaft.

(31) An exhaust outlet control valve 414 releases the exhaust gas from the cylinder volume 402. A cam 416 of a second camshaft is adapted to cause the spring loaded exhaust valve 416 to open and close via the rotation of a camshaft.

(32) The cylinder head 407 comprises various compartments and through-holes for the mounting of e.g. valves 408 and 414 and for e.g. guiding air into the cylinder volume 402 and exhaust gas out from the cylinder volume 402, or for the arrangement of cooling systems. Thus various parts of the cylinder head 407 are susceptible to clogging and may be in need of cleaning, whereby an excitation device 302 may be mounted on the cylinder head 407.

(33) Some of the exhaust gas is circulated back via an exhaust gas recirculation cooler 418 and an exhaust gas recirculation valve 420 to be mixed with air from the air cooler 404 before entering the cylinder volume 402 via the air intake control valve 408. The efficiency of the exhaust gas recirculation cooler 418 and the exhaust gas recirculation valve 420 may be severely affected if subjected to clogging and may therefore also be in need of cleaning by means of an excitation device 302.

(34) The air intake and exhaust outlet system may comprise further components such as backpressure valves and pressure regulators on the exhaust side of the cylinder. Such components are known per se to the skilled person and may be in need of cleaning periodically.

(35) Accordingly, a cleaning system in accordance with the inventive concept may be arranged for cleaning of vehicle component in the gas or fluid flow of the arrangement shown in FIG. 4. Such vehicle components include e.g. temperature sensors 406, pressure sensors, exhaust gas recirculation coolers 418, exhaust gas recirculation valves 420, intake valves 405, intake air coolers 404, cylinder head 407 surfaces, etc. Additional vehicle component which are suitable for cleaning by a cleaning system in accordance with the invention may be cameras and other sensors arranged external on the vehicle and that may be exposed to contaminants from the outside environment.

(36) An excitation device 302 may therefore be attached to the corresponding vehicle component as schematically illustrated in FIG. 4 which illustrates some example applications for the inventive concept.

(37) As is further conceptually illustrated in FIG. 4, the excitation device may be arranged outside the gas or fluid flow and thus transfer the vibrational excitations through the body of the corresponding vehicle component to their surfaces in need of cleaning inside the gas or fluid flow.

(38) The excitation device is controlled by a control unit as is described with reference to FIG. 5.

(39) FIG. 5 illustrates a schematic box diagram of a cleaning system 300 according to embodiments of the invention. The cleaning system 300 comprises an excitation device 302, which is adapted to be attached to a vehicle component 306. The vehicle component 306 is arranged nearby a surface 308 exposed to contaminants, or the vehicle component 306 comprises the surface 308 exposed to contaminants.

(40) The excitation device 302 is configured to cause the surface 308 to mechanically vibrate by transferring a vibrational excitation to the surface 308. A control unit 304 is connected to the excitation device 302 to control the excitation device 302 to provide the vibrational excitation, and to control the frequency of the vibrational excitation. The frequency of the vibrational excitation is based on the configuration of the vehicle component 306.

(41) The control unit 304 may be a dedicated control unit for the cleaning system, or it may be a shared control unit with other electrical/electronical systems of the vehicle.

(42) FIG. 6a is a perspective view of a conceptual example excitation device in the form of a rotating unbalance device 600. FIG. 6b is a front view of the rotating unbalance device 600.

(43) The rotating unbalance device 600 comprises an electric motor 602 which may be able to provide relatively high rotational speeds such as e.g. 50 rpm to 20000 rpm. The rotating unbalance device 600 comprises a rotation member 605 in the form of a disk 608 comprising a mass element 604. The disk 608 is connected to the electric motor 602 via a shaft 606. The electric motor 602 is configured to cause the shaft 606 to rotate about its longitudinal axis 610 such that the disk 608 rotates about its center as shown in FIG. 6b. The axis of rotation 610 is off-center from the center of mass of the rotation member 605 comprising the disk 608 and the mass element 604.

(44) Thus, as the rotation member 605 rotates as illustrated in FIG. 6b, the motion of the inertial mass 604 will shift the center of mass of the rotation member 605, which will cause a vibration of the rotation member 605 at the frequency of the rotation speed of the electric motor 602. This vibration may be transferred to a vehicle component as a vibrational excitation.

(45) Other possible excitation devices may comprise ultra-sound generators for providing a vibrational excitation in the form of an emitted ultra-sound signal, or piezoelectric excitation devices. A piezoelectric excitation device may comprise a piezoelectric component and a power source is configured to provide an excitation voltage signal to the piezoelectric component to cause the piezoelectric component to vibrate. The vibrations may be in the frequency range suitable for removing contaminants from contaminated surfaces of vehicle components.

(46) FIG. 7 conceptually illustrates an excitation device 700 comprising a piezoelectric component 702 and a voltage source 704 configured to provide an excitation voltage signal, conceptually shown as 708 to the piezoelectric component 702. The voltage source 704 is controlled by a control unit (not shown) to control the frequency of the vibrational excitation. Furthermore, the piezoelectric component 702 comprises an additional mass element 706 to provide additional inertia in order to magnify the amplitude of the vibrational excitation. In FIG. 7 the piezoelectric component 702 is illustrated in a bent position (i.e. as part of a vibration) caused by an applied voltage.

(47) Another possible excitation device may comprise oscillating solenoids comprising an electromagnet, which is arranged to attract a conducting metal element, loaded with a spring system. As the metal element is attracted by the electromagnet, it causes the DC electric circuit powering the electromagnet to short circuit, and the spring mechanism repositions the conducting metal element to its initial position (i.e., unloaded state). The repeated motion of the conducting metal element causes a vibration which may depend on element mass and applied voltage. Alternatively, an AC circuit would attract and repel metallic element accordingly.

(48) FIG. 8 is a box diagram of a further embodiment of the invention. This example cleaning system 300 comprises the excitation device 302 and the control unit 304 as described with reference to FIG. 5. Here, the control unit is configured to receive an event signal 801 indicative of internal or external vehicle events. The event signal is received from a vehicle subsystem 802 responsible for various functions or operations of the vehicle. In response to the event signal, the control unit is configured to trigger the excitation device 302 to provide the vibrational excitation.

(49) The event signal 801 is generated in response to a detected internal or external vehicle event. Accordingly, the excitation may be triggered by certain events, so that the vehicle driver/passengers will never notice inharmonious behavior. Further such events include, whenever door closing, wide open throttle, crank-up, etc.

(50) In some embodiments, the excitation device is comprised of an active damper for mechanically damping power train vibrations of a vehicle. FIG. 9 illustrates a schematic sub-frame 900 having thereon an active damper 902. The damper 902 is primarily configured to mechanically damp mechanical vibrations from the power train (not shown) of the vehicle. The active damper 902 may be controlled to vibrate at a frequency suitable for providing a vibrational excitation to a vehicle component (not shown) in need of cleaning. In other words, the active damper 902 may provide a vibrational excitation which is transferred via the sub-frame 900 to the vehicle component connected to the sub-frame 900.

(51) FIG. 10 is a flow-chart of method step according to embodiments of the invention. In step S102 is an event signal indicative of internal or external vehicle events received. An event signal may be received from other vehicle sub systems to determine a present vehicle state. The event signal was in more detail described above. The excitation device is triggered to provide the vibrational excitation at a frequency based on the configuration of the vehicle component in response to receiving the event signal in step S104.

(52) FIG. 11 is a flow-chart of method step according to further embodiments of the invention. In step S202 at least one cleaning evaluation parameter is determined. A control unit communicatively connected to the excitation device may constantly be listening for receiving a signal comprising the cleaning evaluation parameter. Based on the cleaning evaluation parameter, it is determined by the excitation device control unit whether or not cleaning of the vehicle component is required in step S204. Subsequently, in step S206, when it is determined that the vehicle component is in need of cleaning, the excitation device is caused to provide a vibrational excitation at a frequency selected based on the configuration of the vehicle component. In case it is determined by the excitation device control logic that the vehicle component is not in need of cleaning, the control algorithm returns back to state of listening for the signal comprising a cleaning evaluation parameter in order to return to step S202.

(53) Determining whether or not cleaning of the vehicle component is required in step S204 may be based on a mathematical process to compare a pre-determined, pre-registered and/or computed cleaning evaluation parameter to the actual cleaning evaluation parameter. It is determined by the excitation device control unit whether or not cleaning of the vehicle component is required in step S204.

(54) Alternatively, the cleaning evaluation parameter may relate to a pre-determined counter/timer event. Based on a mathematical process to compare a pre-set maximum elapsed time value to the actual cleaning evaluation parameter in the form of an presently elapsed time, it is determined by the excitation device control unit whether or not cleaning of the vehicle component is required in step S204. In other words, when the timer event or counter registers a value that exceeds a pre-set threshold counter or timer value, a cleaning action is due.

(55) When it is determined that cleaning is due, the control unit may be configured to postpone the cleaning event, and i.e. the excitation device postpones providing the vibrational excitation, until an event signal is received. As mentioned above, such event signal may be indicative of various instances such as: whenever door closing, wide open throttle, crank-up, etc. happens.

(56) The control unit may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device, as well as be embedded into the vehicle/power train control logic/hardware. The control unit may also, or instead, include an application-specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

(57) The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

(58) In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.