FIELD OF THE INVENTION

The present invention relates to a process for controlling flow characteristic of electromechanical valve. More particularly, the present invention is directed towards a process of controlling flow characteristic of an electromechanical valve by regulating the upper and lower mechanical stop angular position of the valve through a computing unit.

BACKGROUND OF THE INVENTION

An electromechanical valve is an electrically controlled valve used in variety of applications such as fuel tank valve, purge valves, air bypass valves, vapor blocking valves, refueling vent valve, canister vent valve for controlling flow of fluid such as water like in electric water pump etc. and pneumatic flow like in vacuum solenoid valve, turbocharger solenoid valve, electronic vacuum regulator valve etc. The solenoid valve finds its utility wherever a fluid flow must be controlled/maintained. Therefore, there is always a requirement of precise controlling the flow characteristics of these electromechanical valves.

In an exemplary application, it is seen that in a vehicle using internal combustion during the combustion process with excess oxygen, the combustion temperature increases which leads to the formation of unwanted emissions, such as oxides of nitrogen (NO _x ). The formation of nitrogen oxides increases severely at higher combustion temperatures (above 1600°C or 2912°F). The combustion at higher temperature is harmful to the engine and one of the affects caused by such high combustion temperature is a pre-ignition or detonation. The detonation is responsible for damaging the valves, pistons and other parts of the engine. The commonly used technique to reduce the combustion temperature is the incorporation of solenoid valve working as an exhaust gas recirculation (EGR) valve in the internal combustion engine, that reduces the combustion temperature by diverting the small portion of exhaust gases coming out from the engine exhaust manifold back into the intake manifold. This portion of the engine exhaust gas is mixed with clean air and fuel before entering the engine's combustion cylinders to lower down the combustion temperature and reduces certain exhaust gas emissions. In order to converge the EGR rate to a desired value, a technique for controlling the opening degree of a valve is provided in a vehicle or a throttle valve for adjusting an intake air amount.

Similarly, at various instances the electromechanical valves have to provide precise control of flow characteristics for improved performance.

DE10126580B4, discloses the exhaust gas recirculation method and apparatus are suitable for use in an internal combustion engine. The apparatus includes an engine operating model that is capable of outputting at least one engine operating characteristic, a negative feedback control section that receives feedback on emissions, and generates a negative feedback control signal based on a difference between a predetermined value of exhaust gas recirculation and a negative feedback emission value A positive feedback control section that receives a plurality of engine sensor inputs and generates the plurality of engine sensor inputs in conjunction with the engine operating model to generate a positive feedback control signal, wherein the positive feedback control signal may alter exhaust gas recirculation exhaust gas before the plurality of engine sensor inputs show a deviation from a predetermined emission value, and a controller that the negative feedback control signal and the positive feedback control signal receives and accesses the engine operating model, wherein the controller regulates the exhaust gas flow of the exhaust gas recirculation in response to the negative feedback control signal, the positive feedback control signal and the engine operating model. The main drawback of this invention is that, it controls the flow rate of the valve based on mass flow differential factor which makes the apparatus much complex and time consuming.

US6973941B2, discloses a control valve that reduces noise and controls flow includes a slotted cylindrical skirt and/or a tapered metal ring. The metal ring has a tapered external surface for engaging a matching tapered bore within a valve housing. One embodiment is directed to a control valve including a housing defining a central orifice in fluid in communication with an inlet port and an outlet port, and a movable valve plug assembly having a skirt portion engaged within the central orifice to control fluid flowing through the housing. This invention provides enhanced flow characteristics, but this invention fails to provide an efficient and reliable solution to control the flow characteristic of solenoid valve. Therefore, in order to overcome the aforementioned drawback, there exists a need to develop an efficient and reliable process that controls the flow characteristic of electromechanical valve by handling the upper and lower mechanical stop angular position of the electromechanical valve through a computing unit.

OBJECT OF THE INVENTION

The main object of the present invention is to provide a process of controlling the flow characteristics of electromechanical valve.

Another object of the present invention is to provide an electromechanical valve flow controlling process that controls the flow characteristic by changing UMS (upper mechanical stop) voltage of electromechanical valve.

Yet another object of the present invention is to provide a process that reduces tolerance flow of electromechanical valve.

Yet another object of the present invention is to eliminate the air mass flow sensor by precisely maintaining/controlling the flow characteristic of electromechanical valve.

Still another object of the present invention is to provide a process that is economical and highly reliable and works well for every electromechanical valve type.

SUMMARY OF THE INVENTION

The present invention relates to a process for controlling the flow characteristics of electromechanical valve by variable processing at minimum two different angular flap position preferably at lower and upper mechanical stop angular position of electromechanical valve’s flap/piston/plunger. The flow rate of electromechanical valve is measured at plurality of angular positions/absolute position sensor output voltages continuously by flow meter and commands the computing unit to re-compute value if flow is observed out of specification in order to achieve the reduced flow tolerance.

In an embodiment, the present invention provides a process for controlling flow characteristics of the electromechanical valve comprising the steps of a) mounting a electromechanical valve on the end of line (EOT) station which is a combination of computing station and flow measurement bench, b) processing the electromechanical valve at the end of line (EOL) station with a set of predefined valve angular positions and valve sensor computing voltages, c) checking flow rate of the electromechanical valve at predefined points by a flow meter, d) retrieving the flow rate data as obtained in step (c) by the end of line (EOL) station and calculating the appropriate upper mechanical stop (UMS) voltage, e) repeating step (b) to (d) upon detecting the valve flow rate out of specification until the flow tolerance is reduced to predefined flow tolerance value, and f) obtaining the electromechanical valve with controlled flow characteristics and reduced flow tolerance, wherein the predefined angular positions of the valve are preferably lower mechanical stop (LMS), full close and upper mechanical stop (UMS) angular position of electromechanical valve’s flap; the predefined sensor computing voltages of valve sensor are preferably different voltages of sensor at atleast two valve angular positions including but not limited to lower mechanical stop voltage, upper mechanical stop voltage, and full close voltage wherein the sensor is preferably a hall sensor. Additionally, the electromechanical valve includes but not limited to solenoid valve, exhaust gas recirculation (EGR) valve etc.

In another embodiment, the present invention provides a system for processing an electromechanical valve for controlled flow characteristics and reduced flow tolerance. Said system comprises an air filter an air filter, a dehumidifier, a reservoir, a flow meter, a pressure controller, a pressure gauge, a logic control unit, a computing unit, an electronic control unit, and an electromechanical valve.

In yet another embodiment, the present invention provides an electromechanical valve with controlled flow characteristics comprising of at least one valve body, at least one inlet and outlet port, at least one plunger/piston/flap and at least one sensor wherein said electromechanical valve is processed with a set of predefined valve angular positions and valve sensor computing voltages and allowed to undergo reprocessing again upon detecting a valve flow rate out of specification until the electromechanical valve reaches a flow tolerance reduced to predefined flow tolerance value.

BRIEF DESCRIPTION OF THE DRAWINGS

The object of the invention may be understood in more details and more particularly description of the invention briefly summarized above by reference to certain embodiments thereof which are illustrated in the appended drawings, which drawings form a part of this specification. It is to be noted, however, that the appended drawings illustrate preferred embodiments of the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective equivalent embodiments.

Fig. 1 shows the process flowchart for the electromechanical valve computing and flow verification in accordance with an embodiment of the present invention.

Fig. 2 represents the schematic diagram of hardware used in accordance with an embodiment of the present invention.

Fig. 3 shows the graph of sensor output voltage vs. valve opening angle of the electromechanical valve computed with three different upper mechanical stop voltage in accordance with an example of the present invention.

Fig. 4 shows a graph mapping maximum and minimum flow value obtained by electromechanical valve with or without any reprocessing at various flow checking values in accordance with the present invention.

Figs. 5(a)-(e) shows the flow rate characteristics of EGR valve corresponding to original flow rate and re-computing flow rate in accordance with an example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. The word “processing/processed” and “computing/computed” are interchangeable and defined as providing instructions to the valve or programming of the valve for controlling the electromechanical valve flow characteristics to reduce tolerance flow.

The present invention discloses about a process of controlling electromechanical valve flow characteristic that controls the flow characteristic by changing UMS (upper mechanical stop) voltage of electromechanical valve in order to manufacture the valve with reduced flow tolerance value.

In a main embodiment referring to Fig. 1, the process flow chart for computing valve to control the flow characteristics is illustrated. Said process comprises the steps of: a) mounting a electromechanical valve on the end of line (EOT) station after the assembly is complete; b) processing the valve at said EOT station with predefined valve angular positions preferably at lower mechanical stop (LMS), full close and upper mechanical stop (UMS) and sensor computed in a voltage span ( for example 0.1 V to 4.9 V); c) checking flow rate of the electromechanical valve at a predefined intermediate point between the voltage span by a flow meter; d) retrieving the flow rate data as obtained in step (c) by EOL station and calculating the UMS voltage; e) repeating step (b) to (d) upon detecting the electromechanical valve flow rate out of specification until the flow tolerance is reduced to predefined value; and f) obtaining the electromechanical valve with controlled flow characteristics; wherein the predefined angular positions of the electromechanical valve are preferably lower mechanical stop (LMS), full close and upper mechanical stop (UMS) angular position of electromechanical valve flap; the predefined computing voltages of the sensor are preferably different voltages of the sensor at atleast two valve angular positions including but not limited to lower mechanical stop voltage, full close voltage and upper mechanical stop voltage; the flow rate is checked at atleast one point, however it may be checked at four points i.e. four different output voltages of the sensor as per application and requirement, wherein the sensor is preferably a hall sensor. The valve with controlled flow characteristics are then packed and dispatched as they are achieving a predefined flow tolerance valve.

In another embodiment referring to Fig. 2, the schematic diagram of system used in the present invention is illustrated. Said system (100) comprises of an air filter (01), dehumidifier (02), reservoir (03), flow meter (04), pressure controller (05), pressure gauge (08), logic control unit (07), computing unit (10), ECU (Electronic control unit) (09) and the electromechanical valve (06). Air which passes through the electromechanical valve (06) first gets filtered by using air filter (01) that segregate the contamination present in the air. The dehumidifier (02) is used to remove water particles/moisture from the air to avoid degradation of critical components used in the complete setup. After removing moisture, the air is stored in the reservoir (03) which is further supplied to flow meter (04) during flow checking. The pressure controller (05) controls the pressure of air passing from flow meter (04) to electromechanical valve (06). It receives signal from logic control unit (07), in analog or digital form, to control the pressure and accordingly pressure at the inlet of the electromechanical valve (06) is going to be change, flow is checked at an inlet pressure that is customizable as per requirement and application of the electromechanical valve. The flow meter (04) measures the air flow passing through it and the air flow measurement is done at atleast one point in TPM (Titer per Minute) unit of predefined voltage of hall sensor. The reading of measured flow rate is stored in logic control unit (07). The number of points of predefined voltage of hall sensor at which flow measurement is done is also customizable as per requirement and application of electromechanical valve.

The pressure gauge (08) measures the pressure at the inlet of the electromechanical valve (06) and provides signal to logic control (07) unit to take decision for pressure controller (05). The logic control unit (07) gives signal to computing unit (10) to start computing by feeding the % Vcc value to computing unit (10) and take decision for OK and NG parts based on defined flow specifications. It guides the computing unit (10) to re-compute the valve (06) if found to be out of specification. Based on the signal from logic control unit (07), the computing unit (10) processes the valve (06). The computing unit (10) teaches the valve (06) in % Vcc (sensor input voltage) form and the ECU (Electronic control unit) (09) is used to open the electromechanical valve (06) to desired position during flow checking based on the computing.

In yet another embodiment, the present invention provides an electromechanical valve with controlled flow characteristics comprising of at least one valve body, at least one inlet and outlet port, at least one plunger/piston/flap and at least one sensor wherein said electromechanical valve is processed with a set of predefined valve angular positions and valve sensor computing voltages and allowed to undergo reprocessing again upon detecting a valve flow rate out of specification until the electromechanical valve reaches a flow tolerance reduced to predefined flow tolerance value. The electromechanical valve achieves a reduced flow tolerable compared to the initial tolerance. Predefined angular positions of the electromechanical valve include but are not limited to lower mechanical stop (LMS), full close and upper mechanical stop (UMS) angular position of valve flap/plunger/piston. Said predefined sensor computing voltages of sensor are preferably different voltages of sensor at atleast two valve angular positions that include but are not limited to lower mechanical stop voltage, upper mechanical stop voltage and full close voltage.

EXAMPLE 1 PROCESSING EGR VALVE TO CONTROL THE FLOW CHARACTERISTICS

Flow characteristics of an EGR valve of diameter 24 ± 0.5 mm were controlled by computing in accordance with the present invention. The EGR valve was mounted at the EOL and computed at three different angular positions i.e. lower mechanical stop (LMS), full close & upper mechanical stop as listed in Table 1. Table 1 shows the three different angular position of EGR valve along with hall sensor % Vcc voltage and processing voltage at which the EGR valve was computed.

Table 1

Computing EGR valve at different angular positions

Table 2 shows the flow checking points of EGR valve at four different sensor output voltages and angular positions respectively. On completion of flow rate measurement, when flow results were found to be out of specification, the EGR valve was reprogrammed by selecting new upper mechanical stop (UMS) voltage in order to take the flow results within the specification. Table 2

Flow rate checking at different sensor voltage Table 3 shows the difference between normally programmed valves and re-programmed valve. For the process of re-computing EGR valve, first two voltages of valve angular position i.e., lower mechanical stop voltage and full close voltage were kept constant and only upper mechanical stop voltage was changed again and again until the flow results turn out to be within the specification. Upper mechanical stop voltage is calculated on the basis of farness of actual flow from target specification. As there are four flow checking points, it may also be possible that all four points may not be equally far from target specification then it depends on user requirement that which one to be targeted first.

Table 3

Re-computing at different UMS voltage Now referring to Fig. 3, the graph of sensor output voltage vs. valve opening angle of EGR valve programmed with three different upper mechanical stop voltage is shown. From graph it is observed that for the same sensor output voltage (e.g. 2.5 V), valve opening for all three valves (valve 1, 2 and 3) is different i.e. -33°, -29° and -37°. It is also known that the flow rate is directly proportional to the valve opening angle i.e., the more is the valve opening angle, the more is the flow rate.

Experimental Analysis

A series of experiment were performed for comparing the flow characteristics of EGR valve with and without re-computing. The reprogrammed valves flow observation is shown in Table 4.

Table 4

Reprogrammed valves flow observation

Fig. 4 shows a graph mapping the minimum and maximum values of the electromechanical valve without and with reprogramming the valve for controlled flow characteristics and reduced flow tolerance in accordance with data in Table 4. The minimum valve flow in an electromechanical valve without any reprogramming at 1.8 V is 60 LPM however the maximum is 91 LPM, hence the delta/difference is ~31 LPM, however after reprogramming under predefined angular positions and sensor computing voltages the minimum flow value obtained at 1.8 V is 68 LPM and the maximum value obtained is 82 LPM. Therefore, the reprogramming has reduced the delta/difference to 14 LPM. It shows that the flow tolerance is reduced by -60% of the initial value.

Figs. 5(a)-(e) represent the flow characteristics of EGR valve corresponding to original flow before re-computing and flow after re-computing on the basis of experimental data shown in Table 4. From these characteristics it is observed that the flow characteristics of EGR valve after re-computing gives better result as compared to original flow before re- computing.

Table 5 compares the tolerance value obtained from conventional and present process. The present process includes the tolerance flow obtained from re-computing of EGR valve by changing upper mechanical stop (UMS) voltage whereas conventional process does not include such facilities.

Table 5

Comparison between tolerance flow obtained from conventional and present process tolerance in the process as per present invention is ranging from 5.52% to 16.48% of mean specification. Therefore, with this new process the flow tolerance is reduced by -60% of initial tolerance.

Similar experiments were conducted on various other electromechanical valve valves such as a purge valve, an isolation valve, direct-acting valves, pilot-operated valves etc. and it was observed that all the said valves exhibit similar flow characteristics i.e., the flow tolerance ranged from 5.52% to 16.48% of mean specification and, the flow tolerance is reduced by -60% of initial tolerance.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.