WO2025242544A1

WO2025242544A1 - Diagnostic system for a solenoid-operated valve and method thereof

Info

Publication number: WO2025242544A1
Application number: PCT/EP2025/063442
Authority: WO
Inventors: Ramesh Murthy
Original assignee: Valeo Systemes dEssuyage SAS
Current assignee: Valeo Systemes dEssuyage SAS
Priority date: 2024-05-21
Filing date: 2025-05-15
Publication date: 2025-11-27
Anticipated expiration: 2026-11-21

Abstract

The present invention pertains to a diagnostic system (100) for detection of operational state of a solenoid-operated valve (102). A flowmeter (104) is provided in a fluid line (106) at inlet side of the valve (102). Electric power from power source (122) is supplied to the valve (102) and to the flowmeter (104) by a power line (108) including a differential power line (108a). Upon actuation, the valve (102) allows fluid to flow through fluid outlet (106b) and the flowmeter (104) detects rate of flow of fluid to generate corresponding single data. The signal from the flowmeter (104) is transmitted to a control unit (118) through the differential power line (108a). The control unit (118) determines operational state of the valve (102) based on the received signal.

Description

DIAGNOSTIC SYSTEM FOR A SOLENOID-OPERATED VALVE AND METHOD THEREOF

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a diagnostic system for a solenoid-operated valve and method thereof, and more particularly to a system and a method for detection of plunger position/travel in a solenoid-operated valve or degree of opening of the solenoid-operated valve.

BACKGROUND OF THE INVENTION

[0002] Motor vehicles include various components such as camera, radar sensor, lidar sensor and/or other sensors, headlamps, tail lamps, front and rear windshields etc. that are mounted on exterior side of the vehicle for performing their intended functions. Surrounding conditions may lead to contamination of the sensor lens/ outer surface, such as accumulation of water drops, dust, debris, ice and snow etc. These contamination affects the functioning of the component(s). Various cleaning systems are used to remove these contaminations from the lens/surface of the sensors/ components .

[0003] A conventional cleaning system generally uses pressurized water or cleaning fluid for cleaning the sensors/components. The water/fluid from a reservoir may be pumped using a high pressure pump and the pressurized cleaning fluid is sprayed on the surface to be cleaned. These cleaning systems include solenoid-operated valve(s) provided in fluid line for controlling flow of the fluid to be sprayed on the surface to be cleaned. There may be provided plurality of valves to control cleaning of plurality of sensors/components.

[0004] Solenoid-operated valve is a mechanically movable device having components such as plunger, spring, control valve etc. During usage, the functioning of the solenoid may get affected due to aging, fatigue or plunger obstruction due to any other reason. This may lead to partially open state of the valve when a completely open state i.e. 100% degree of opening of the solenoid is desired. When completely open state of solenoid is desired and only partial open state is achieved, it leads to failure to properly clean the surface of component.

[0005] To address this issue, there are provided a custom made solenoid-operated valves having inbuilt approaches to sense these situations. However, these custom made valves require additional hardware components such as pins and/or processor(s), leading to significant increase in cost of the solenoid-operated valve and design complexity. [0006] Other available solutions may include general solenoid with back EMF/ current slope/ inductance measurement/processing techniques. However, this solution has disadvantages such as requirement of additional processing power due to its dependence on supply voltage which varies (e.g. from 6V to 16V). Further, a sensor may be integrated in the solenoid for detection of plunger position. However, it requires additional harness for transmission of data from sensor to controller. Thus, it has disadvantage of inconsistency in the measurements due to long unshielded harness leading to the critical issue of electromagnetic coupling.

[0007] The prior art and the conventional techniques have various disadvantages as described above and there is a need for a system for detection of plunger position/travel or degree of opening of the solenoid-operated valve, that can overcome the disadvantages of the conventional techniques.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to solve the disadvantages described above of conventional solenoid-operated valves. In particular, the object of the present invention is to provide a diagnostic system and method for detection of operational state of a solenoid-operated valve.

[0009] Another obj ect of the present invention is to provide a system and method for detection of degree of opening of a solenoid-operated valve by using a flowmeter.

[0010] Yet another object of the present invention is to provide system and method for detection of faulty solenoid-operated valve.

[0011] According to the present invention, there is provided a diagnostic system for a solenoid-operated valve. The system comprises a solenoid-operated valve provided in a fluid line and a flowmeter positioned in the fluid line at fluid inlet side of the solenoid-operated valve. The system further comprises a power source adapted to provide electric power to the solenoid- operated valve and to the flowmeter through a power line. The flowmeter detects rate of flow of fluid and transfers corresponding signal to a control unit. The control unit is adapted to determine operational state of the solenoid-operated valve based on the signal received from the flowmeter. The power line includes a DC (direct current) power line adapted to supply electric power from the power source to the solenoid-operated valve and to the flowmeter. [0012] In a non-limiting embodiment of the present invention, the flowmeter may include a reed switch/sensor. The reed switch flowmeter has advantages such as low cost, long life cycle, no requirement of additional circuitry and power, no impact of temperature etc.

[0013] In an alternate embodiment of the present invention, the flowmeter may include a hall effect sensor. The hall effect flowmeter has advantages such as low cost, long life cycle etc.

[0014] In another alternate embodiment of the present invention, the flowmeter may include an ultrasonic sensor. The ultrasonic flowmeter has advantage of not obstructing the fluid flow through the flowmeter.

[0015] In a non-limiting embodiment of the present invention, the flowmeter generates a single ended pulse corresponding to the rate of flow of the fluid flowing through the flowmeter.

[0016] In a non-limiting embodiment of the present invention, the corresponding signal may be transferred to the control unit (118) through a data bus, in particular a CAN bus (controller area network bus) or LIN bus (local interconnect network) or analog bus. It is to be understood that any other dedicated or multiplexed data transmission forms may instead be employed.

[0017] In a non-limiting embodiment of the present invention, at least a part of the power line may be a differential power line. The corresponding signal may be transferred to the control unit through said differential power line. The power line may include the differential power line and the DC power line such that the DC power line is adapted to supply electric power from the power source to the solenoid-operated valve and to the flowmeter. Low pass filter(s) may be provided between the DC power line and the differential power line to attenuate power line noise.

[0018] In a non-limiting embodiment of the present invention, the system further includes a first amplifier to convert the single ended pulse into a differential pulse and a first capacitor to inject the differential pulse into the differential power line. The first amplifier may be referred to as a differential amplifier that amplifies and converts the single ended pulse generated by the flowmeter into the differential pulse. The first capacitor may also be referred to as coupling capacitor that injects the differential pulse into the differential power line. The first capacitor blocks low frequencies such as DC signal and allows high frequencies such as AC signal to pass through it. The differential pulse is transferred through the differential power line. The first amplifier is supplied with the electric power from the power source through the DC power line. [0019] In another non-limiting embodiment of the present invention, the system further comprises a second capacitor adapted to extract the differential pulse from the differential power line. The second capacitor may also be referred to as coupling capacitor or decoupling capacitor and it blocks low frequencies such as DC signal and allows high frequencies such as AC signal to pass through it.

[0020] In a non-limiting embodiment of the present invention, the system further comprises a second amplifier to convert the extracted differential pulse into a single ended pulse for providing the single ended pulse to the control unit. The second amplifier may be referred to as a single ended amplifier that amplifies and converts the differential pulse extracted from the differential power line into a single ended pulse. The converted single ended pulse is supplied to the control unit for processing. The second amplifier is supplied with the electric power from the power source through the DC power line.

[0021] In a non-limiting embodiment of the present invention, the control unit is adapted to determine operational state of the solenoid-operated valve by comparing frequency of the received single ended pulse with a predefined frequency data.

[0022] In a non-limiting embodiment of the present invention, the operational state of the solenoid-operated valve determined by the control unit may include degree of opening of the valve and/or travel of a plunger in the solenoid-operated valve. The operational state of the solenoid-operated valve may also include position of the plunger in the solenoid-operated valve. The predefined frequency data may include a reference data including correlation between degree of opening of solenoid and/or position/travel/movement of solenoid plunger and frequency of the single ended pulse corresponding to fluid flow rate.

[0023] In a non-limiting embodiment of the present invention, the control unit is further adapted to generate an indication signal corresponding to the determined operational state of the valve. The indication signal may be provided to vehicle infotainment or instrument cluster or any other user interface in the vehicle to show the real time operational state of the valve to user. For example, the degree of opening of the valve i.e. between 0% - 100% opening or plunger travel may be indicated to the user.

[0024] In a non-limiting embodiment of the present invention, the control unit is further adapted to generate a warning signal if the determined operational state of the valve deviates from predefined criteria. For example, the criteria for the warning signal may be predefined as degree of opening being greater than or equal to 80%. If the degree of opening determined by the control unit based on signal from flowmeter is less than 80%, the control unit generates the warning signal that may be provided to the user through relevant user interface.

[0025] The present invention also relates to a motor vehicle comprising at least one sensor and at least one sensor cleaning mechanism having the diagnostic system according to any of preceding embodiments. The diagnostic system may be used to detect operational state of multiple solenoid-operated valve provided in one or more fluid lines.

[0026] The present invention also relates to a diagnostic method for a solenoid-operated valve. The method comprises steps of supplying electric power to a solenoid-operated valve and to a flowmeter through a power line, detecting fluid flow rate in a fluid line at fluid inlet side of the solenoid-operated valve by the flowmeter, transferring the signal corresponding to the fluid flow rate from the flowmeter to a control unit through a differential power line and determining operational state of the solenoid-operated valve by the control unit based on the signal received from the flowmeter. The power line may include the differential power line and a DC (direct current) power line(s).

[0027] In a non-limiting embodiment of the present invention, the method further includes attenuating power line noise by at least one low pass filter. The low pass filters may be provided in the power line between the differential power line and the DC power line.

[0028] In a non-limiting embodiment of the present invention, the step of transferring the signal to the control unit further includes a sub-step of converting a single ended pulse generated by the flowmeter into a differential pulse by a first amplifier.

[0029] In a non-limiting embodiment of the present invention, the step of transferring the signal to the control unit further includes a sub-step of injecting the differential pulse into the differential power line by a first capacitor and extracting the differential pulse from the differential power line by a second capacitor.

[0030] In a non-limiting embodiment of the present invention, the step of transferring the data to the control unit further includes a sub-step of converting the extracted differential pulse into a single ended pulse by a second amplifier and providing the single ended pulse to the control unit. [0031] In a non-limiting embodiment of the present invention, the method further comprises a step of generating an indication signal corresponding to the determined operational state of the valve.

[0032] In a non-limiting embodiment of the present invention, the method further comprises a step of generating a warning signal if the determined operational state of the valve deviates from predefined criteria.

BRIEF DESCRIPTION OF DRAWINGS

[0033] To complete the description and to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate an embodiment of the invention, which should not be construed as restricting the scope of the invention, but only as an example of how the invention can be carried out. The drawings comprise the following characteristics.

[0034] Fig i illustrates a schematic block diagram of a diagnostic system for a solenoid- operated valve, according to an embodiment of the present invention;

[0035] Fig.2 illustrates a schematic block diagrams of the diagnostic system including reed switch flowmeter, according to an embodiment of the present invention; and

[0036] Fig.3 illustrates a flow diagram of diagnostic method for the solenoid-operated valve, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Unless specifically indicated otherwise, technical characteristics described in detail for a given embodiment may be combined with the technical characteristics described in the context of other embodiments described by way of example and not limitation.

[0038] Items shown in the drawings are not to scale and are simplified to increase clarity of disclosure.

[0039] In the following description, the expression “operational state” of the solenoid- operated valve refers to open/closed state of the valve or may also refer to degree of opening of the solenoid-operated valve and/or position/travel/movement of the plunger of the solenoid- operated valve. Moreover, the expression “differential power line” may refer to power line that can carry differential pulse signal as well as electric power simultaneously. The expression “differential power line” may be alternatively used with the terms “twisted pair power cable”, “data over power line” or “power line communication”. Further, the expression “predefined frequency data” may refer to reference data including correlation between degree of opening and frequency of the single ended pulse and/or between position/travel/movement of plunger and frequency of the single ended pulse that corresponds to fluid flow rate. Moreover, “first amplifier” may also be referred to as “differential amplifier” and the “second amplifier” may also be referred to as “single ended amplifier”. Further, the expression “signal” refers to electrical signal that may be in the form of single ended pulse and/or differential pulse. Further, the “first capacitor” and the “second capacitor” are coupling capacitors that are used to couple or link only the AC signals from one circuit element to another. These capacitors respond to different frequencies in different ways. These capacitors have very high impedance or resistance to the low frequency signals, therefore the low frequency signals are blocked from going through. Whereas, these capacitors have low impedance or resistance to high frequency signals, therefore the high frequency signals are passed through them easily.

[0040] Fig 1 shows a block diagram of a system 100 for detecting operational state of a solenoid-operated valve 102. As shown, the solenoid-operated valve 102 is provided in a fluid line 106 to control flow of fluid through the fluid line 106. The solenoid-operated valve 102 may be used in cleaning mechanisms used for cleaning sensor(s) or camera or other components in a motor vehicle. Moreover, solenoid-operated valve(s) 102 may be used for other purposes where regulation of fluid flow is required.

[0041] Further, a flowmeter 104 is provided in the fluid line 106 at fluid inlet side of the valve 102 such that the rate of flow of the fluid flowing through a fluid inlet 106a is detected by the flowmeter 104. The solenoid-operated valve 102 and the flowmeter 104 are connected to a power source 122 through a power line 108. The power line 108 includes a differential power line 108a and a DC (direct current) power line 108b. When no power is supplied to the solenoid- operated valve 102, the valve 102 remains in closed state i.e. degree of opening of the valve 102 is 0%. When electric power from the power source 122 is supplied to the solenoid-operated valve 102, the valve 102 allows flow of fluid through a fluid outlet 106b i.e. the solenoid- operated valve 102 is in open state or degree of opening of the valve 102 is 100%. The flowmeter 104 detects the rate of flow of the fluid through the fluid line 106 and generates corresponding signal. [0042] The electric power from the power source 122 may be transferred to the differential power line 108a through the DC power line 108b. Further, the electric power from the differential power line 108a is supplied to the solenoid-operated valve 102 and to the flowmeter 104 through the DC power line 108b. A first low pass filter 110a and a second low pass filter 110b may be provided between the differential power line 108a and the DC power line(s) 108b to attenuate the power line noise.

[0043] The flowmeter 104 is adapted to generate signal in the form of a single ended pulse 109a corresponding to the rate of flow of the fluid through the flowmeter 104. This signal 109a is supplied to a first amplifier 112 which amplifies and converts the single ended pulse 109a into a differential pulse 107a. The first amplifier 112 is supplied with electric power from the power source 122 through the DC power line 108b. A first capacitor 114a is used to inject the differential pulse 107a into the differential power line 108a. The differential pulse 107a corresponding to the fluid flow rate is transferred over the differential power line 108a and extracted from the differential power line 108a by a second capacitor 114b. The extracted pulse signal 107b is amplified and converted into a single ended pulse 109b by a second amplifier 116. The single ended pulse 109b from the second amplifier 116 is transferred to a control unit 118. The second amplifier 116 is supplied with electric power from the power source 122 through the DC power line 108b.

[0044] The control unit 118 analyzes the received single ended pulse 109b to determine operational state of the solenoid-operated valve 102. The control unit is further adapted to determine degree of opening of the solenoid-operated valve 102 and/or travel of solenoid plunger. The control unit 118 may generate an indication signal corresponding to the determined operational state of the valve 102 and send it to any desired user interface.

[0045] In an embodiment of the present invention, an audio, visual or audio-visual indicator may be provided in vehicle to indicate the operational state of the solenoid-operated valve 102 based on the indication signal from the control unit 118. Further, the control unit 118 may be adapted to generate a warning signal if the determined operational state of the valve 102 deviates from predefined criteria. For example, the predefined criteria may be set as degree of opening being greater than or equal to 80%, then the control unit 118 generates the warning signal if the determined degree of opening of the solenoid-operated valve 102 is less than 80%. The predefined criteria may be set for any value between 0% to 100% degrees of opening. The generated warning signal may be sent to any desired user interface. The predefined criteria may be formulated in terms of plunger travel or position of plunger in the solenoid-operated valve 102 and the warning signal may be generated accordingly.

[0046] In an alternate embodiment of the present invention, multiple solenoid-operated valves 102 may be provided in one or more fluid lines 106. The flowmeter 104 may be provided in the fluid lines 106 on inlet side of each solenoid-operated valve 102. The control unit 118 is adapted to receive signal corresponding to rate of fluid flow through each flowmeter 104 and distinctively determines the operational state of each of the solenoid-operated valve 102. The indication regarding the faulty valve(s) 102 or the valve(s) 102 deviating from the predefined criteria may be given to the user, making it easier to identify and repair/replace the faulty valves(s) 102.

[0047] In a preferred embodiment of present invention, the differential power line 108a is provided between the first low pass filter 110a and the second low pass filter 110b.

[0048] In a preferred embodiment of the present invention, as shown in Fig. 2, the solenoid- operated valve 102 includes a plunger 102a surrounded by a coil 102b. When electric power is supplied to the coil 102b, the plunger 102b is retracted due to electromagnetic flux produced by the coil 102b, thereby compressing a spring 102c and opening a passage 102d for allowing fluid flow. When electric power is stopped, the spring 102c pushes the plunger 102a thereby extending the plunger 102a to close the passage 102d. The fluid line 106 may be a pipe/hose carrying cleaning fluid or water or any other fluid from a reservoir (not shown) to a spray nozzle or any other component for cleaning of vehicle component(s). A pump (not shown) may be used to supply fluid or water from the reservoir to the fluid line 106. The flowmeter 104 may include a rotor 104a having a magnet 104b mounted on any blade of the rotor 104a and a reed switch 104c. When the fluid flows through the flowmeter 104, it rotates the rotor 104a thereby rotating the magnet 104b. When an electric power is supplied to the flowmeter 104, the reed switch 104c generates a single ended pulse 109a when the magnet 104b comes in proximity and moves away from the reed switch 104c. The rotational speed of the rotor 104a is proportional to the rate of flow of the fluid/water through the flowmeter 104. The reed switch 104c generates signal in the form of single ended pulse 109a having frequency corresponding to the rotational speed of the rotor 104a.

[0049] This single ended pulse 109a is converted into differential pulse 107a by the first amplifier 112 and the differential pulse 107a is injected into the differential power line 108a by the first capacitor 114a. The differential pulse 107a is transferred through the differential power line 108a. The second capacitor 114b extracts the differential pulse 107b from the differential power line 108a and supplies it to the second amplifier 116. The second amplifier 116 amplifies and converts the differential pulse 107b into the single ended pulse 109b and supplies it to the control unit 118. The electric power is supplied from the power source 122 to the first amplifier 112 through the DC power line 108b. Moreover, the electric power is supplied to the second amplifier 116 from the power source 122 through the DC power line 108b.

[0050] In an embodiment of the present invention, electronic components such as driver 120 may be used with the power source 122. Further, the flowmeter 104 may include any other functional electronic components/circuit. It is to be understood that a module having the solenoid-operated valve 102 and the flowmeter 104 by be distantly located from the power source 122 and the control unit 118. Therefore, transferring the signal over a long distance through the differential power line 108a results in least power line noise and improved signal accuracy.

[0051] In another embodiment of the present invention, there is provided a motor vehicle (not shown) having at least one cleaning mechanism for cleaning vehicle components such as sensors, camera, windshield etc. The cleaning mechanism may include one or more solenoid- operated valve(s) 102 to regulate pressurized fluid used for cleaning. The cleaning mechanism further includes the diagnostic system 100 as disclosed above.

[0052] In another embodiment of the present invention, the flowmeter 104 may include any of a hall effect sensor or an ultrasonic sensor or any other suitable sensor that can detect the rate of flow of fluid through the fluid line 106 and generate corresponding electrical signal.

[0053] Fig 3 illustrates a flow diagram of method for detecting the operational state of the solenoid-operated valve 102. The electric power supply from the power source 122 is enabled to actuate the solenoid-operated valve 102. The electric power is supplied to the solenoid- operated valve 102 and to the flowmeter 104 through the power line 108 having the differential power line 108a and the DC power line 108b. The first low pass filter 110a and the second low pass filter 110b connected between the differential power line 108a and the DC power line(s) attenuates the power line noise. The solenoid-operated valve 102 gets actuated and the plunger 102a of the solenoid-operated valve 102 is retracted thereby allowing flow of fluid through the fluid outlet 106b. The flowmeter 104 generates a single ended pulse 109a corresponding to the rate of flow of the fluid flowing through the passage 102d of the flowmeter 104. The single ended pulse 109a is converted into differential pulse 107a by the first amplifier 112. Then the converted differential pulse 107a is injected into the differential power line 108a by the first capacitor 114a. The differential pulse 107a travels through the differential power line 108a and the second capacitor 114b extracts the differential pulse 107b from the differential power line 108a. Then the extracted differential pulse 107b is converted into single ended pulse 109b by the second amplifier 116. This single ended pulse 109b is supplied to the control unit 118. The control unit 118 compares frequency of the received single ended pulse 109b with predefined frequency data to determine the operational state of the solenoid-operated valve 102. The predefined frequency data may include the values of degree of opening and/or values of travel of plunger and corresponding values of frequency of the single ended pulse. The control unit 118 compares frequency of the received single ended pulse 109b with predefined values of the frequencies and determines corresponding degree of opening or travel of plunger in the solenoid-operated valve 102. The control unit 118 generates an indication signal that may be used to communicate the operational state of the valve 102 to the user.

[0054] The control unit 118 may also generate a warning signal based on a predefined criteria to warn the user about faulty valve 102. For example, the predefined criteria may be set as degree of opening being greater than or equal to 80%, then the control unit 118 generates the warning signal if the determined degree of opening of the solenoid-operated valve 102 is less than 80%. The predefined criteria may be set for any value between 0% to 100% degrees of opening. The generated warning signal may be sent to any desired user interface. The predefined criteria may be formulated in terms of plunger travel or position of plunger in the solenoid-operated valve 102 and the warning signal may be generated accordingly.

[0055] In an embodiment of the present invention, the indication and/or warning may be provided to the user on vehicle dashboard or any other user interface.

[0056] In an embodiment of the present invention, the steps of the diagnostic method are performed upon activation of diagnostic feature by user through user interface or may be initiated automatically based on predefined vehicular conditions such as but not limited to turning on the vehicle or turning on the ignition etc.

[0057] The present invention has advantageous effect of providing the diagnostic system 100 for the solenoid-operated valve 102 without needing any additional harness. Transferring the signal data through differential power line 108a reduces electromagnetic coupling issues and increases accuracy of the signal data irrespective of power source voltage and temperature. [0058] The invention has been described with respect to the preceding embodiment, which presents one particular means of data transmission, i.e. over a differential power line. However, and solely in light of the foregoing disclosure, it will also be understood that other data transmission means, for instance a LIN bus (local interconnect network) or CAN bus (controller area network bus) or analog bus or other dedicated or multiplexed data transmission forms, might instead be employed. It will therefore be understood that such alternative data transmission means, while not illustrated in the foregoing discussion and figures, are also within the scope of the present invention.

[0059] 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. In addition, the skilled person readily realizes that the different embodiments described herein may be combined freely to obtain new combinations.

[0060] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. 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. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantages.

LIST OF REFERENCE SIGNS b ! Fluid outlet

Claims

CLAIM

[Claim 1] A diagnostic system (100) for a solenoid actuator, the system comprising: a solenoid-operated valve (102) provided in a fluid line (106); a flowmeter (104) positioned in the fluid line (106) at fluid inlet side of the solenoid-operated valve (102); and a power source (122) configured to provide electric power to the solenoid- operated valve (102) and to the flowmeter (104) through a power line (108), wherein the flowmeter (104) detects rate of flow of fluid and transfers corresponding signal to a control unit (118), the control unit (118) being configured to determine operational state of the solenoid-operated valve (102) based on the signal received from the flowmeter (104).

[Claim 2] The system (100) according to claim 1, wherein the flowmeter (104) includes a reed switch, a hall effect sensor and/or an ultrasonic sensor.

[Claim 3] The system (100) according to claim 1 or claim 2, wherein the flowmeter (104) generates a single ended pulse (109a) corresponding to the rate of flow of the fluid flowing through the flowmeter (104).

[Claim 4] The system (100) according to any of preceding claims, wherein the corresponding signal is transferred to the control unit (118) through a data bus, in particular a CAN bus or LIN bus or analog bus.

[Claim 5] The system (100) according to any of claims 1 to 3, wherein at least a part of the power line (108) is a differential power line (108a), the corresponding signal being transferred to the control unit (118) through said differential power line (108a).

[Claim 6] The system (100) according to claim 5, further comprising a first amplifier (112) to convert the single ended pulse (109a) into a differential pulse (108a) and a first capacitor (114a) to inject the differential pulse (108a) into the differential power line (108a).

[Claim 7] The system (100) according to claim 6, further comprising a second capacitor (114b) configured to extract the differential pulse (107b) from the differential power line (108a).

[Claim 8] The system (100) according to claim 7, further comprising a second amplifier (116) to convert the extracted differential pulse (107b) into a single ended pulse (109b) for providing the single ended pulse (109b) to the control unit (118).

[Claim 9] The system (100) according to claim 8, wherein the control unit (118) is configured to determine operational state of the solenoid-operated valve (102) by comparing frequency of the received single ended pulse (109b) with a predefined frequency data.

[Claim 10] The system (100) according to claim 9, wherein the control unit (118) is further configured to generate an indication signal corresponding to the determined operational state of the actuator (102).

[Claim 11] The system (100) according to claim 9 or claim 10, wherein the control unit (118) is further configured to generate a warning signal if the determined operational state of the actuator (102) deviates from predefined criteria.

[Claim 12] A motor vehicle, comprising: at least one sensor; and at least one sensor cleaning mechanism having the diagnostic system (100) according to any of preceding claims.

[Claim 13] A diagnostic method for a solenoid-operated valve, the method comprising steps of: supplying electric power to a solenoid-operated valve (102) and to a flowmeter (104) through a power line (108); detecting fluid flow rate in a fluid line (106) at fluid inlet side of the solenoid- operated valve (102) by the flowmeter (104); transferring the signal corresponding to the fluid flow rate from the flowmeter (104) to a control unit (118) through a differential power line (108a); and determining operational state of the solenoid-operated valve (102) by the control unit (118) based on the signal received from the flowmeter (104).

[Claim 14] The method according to claim 13, wherein the step of transferring the signal to the control unit (118) includes a sub-step of converting a single ended pulse (109a) generated by the flowmeter (104) into a differential pulse (107a) by a first amplifier (112).

[Claim 15] The method according to claim 14, wherein the step of transferring the signal to the control unit (118) further includes a sub-step of injecting the differential pulse (107a) into the differential power line (108a) by a first capacitor (114a) and extracting the differential pulse (107b) from the differential power line (108a) by a second capacitor (114b).

[Claim 16] The method according to claim 15, wherein the step of transferring the data to the control unit (118) further includes a sub-step of converting the extracted differential pulse (107b) into a single ended pulse (109b) by a second amplifier (116) and providing the single ended pulse (109b) to the control unit (118).

[Claim 17] The method according to any one of claims 13 to 16, further comprising a step of generating an indication signal corresponding to the determined operational state of the actuator (102) and/ or generating a warning signal if the determined operational state of the actuator (102) deviates from predefined criteria.