Abstract:
A fuel flow regulating valve installable on a fuel flow line between a fuel flow inlet and a fuel flow outlet and movable between an open position in which it allows a continuous flow of fuel from the fuel flow inlet to the fuel flow outlet through the line and a closed position in which it interrupts the flow of fuel, an electromagnetic actuator connected with the regulating valve and actuating the latter so as to adjust an opening degree of the regulating valve, and a control unit for controlling the electromagnetic actuator in dependence on at least one parameter of the fuel flow so as to correspondingly adjust the opening degree of the regulating valve.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to fuel flow regulating valves for regulating a fuel flow. 
   Such regulating valves are well known in the art. One of such fuel flow regulating valves is disclosed for example in the SRC publication no. 11305-5DO1 “An Electronic Regulator for Automotive Gaseous Fuels Applications”, S. Hill, M. Sulatisky, K. Young of Saskatchewan Research Concept, and H. Portman, U. Imhof of Dynetek Industries LTD, Canada. The electronic pressure regulator is based on a pilot-operated principle and uses an on/off high-speed solenoid valve for fuel metering. Electronic diesel and gasoline pressure regulators are normally bypass regulators where the exiting fuel is returned to the fuel tank. Since this is not possible in hydrogen or natural gas fuel systems, because the fuel tank is at a higher pressure than the regulator outlet pressure, it is desirable to regulate the inlet of the fuel metering system. Some diesel and gasoline pressure regulating systems throttle or otherwise control a high pressure pump. However, they need a pump to raise a fuel pressure to the pressure stored in an accumulator or fuel rail. This is not an option for gaseous fuel stored under high pressure, such as hydrogen or natural gas. Electronic air pressure regulators have been also used for various applications. However, they are allowed to vent excessive pressure to the atmosphere. Since the working fluid of this pressure regulator may be a combustible fuel, venting excessive working fluid (fuel) is not an option. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of present invention to provide an electronic pressure regulator which avoids the disadvantages of the prior art. 
   In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a fuel flow regulating valve installable on a fuel flow line between a fuel flow inlet and a fuel flow outlet and movable between an open position in which it allows a continuous flow of fuel from the fuel flow inlet to the fuel flow outlet through the line and a closed position in which it interrupts the flow of fuel; an electromagnetic actuator connected with said regulating valve and actuating the latter so as to continuously adjust an opening degree of said regulating valve; and control means for controlling said electromagnetic actuator in dependence on at least one parameter of the fuel flow so as to correspondingly adjust the opening degree of said regulating valve. 
   When the electronic fuel flow regulator is designed in accordance with the present invention, it eliminates the disadvantages of the prior art. 
   In accordance with other novel features of the present invention, the control means receives signals from sensing means for sensing an outlet fuel pressure after the regulating valve, and/or from sensing means for sensing an inlet fuel pressure before the regulating valve, and/or from means for sensing a displacement of a valve member of the regulating valve, so as to generate corresponding signals to the electromagnetic actuator and to correspondingly adjust the opening degree of the regulating valve. 
   The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view schematically showing a fuel flow regulating valve in accordance with the present invention; 
       FIG. 2  is a view schematically showing a regulating valve of the inventive fuel flow regulating valve; and 
       FIG. 3  is a view schematically showing a basic pressure regulator composed of loop in accordance with the present invention; 
       FIGS. 4 and 5  are views illustrating increasing or decreasing of the gains in response to a corresponding error; and 
       FIG. 6  is a view illustrating a typical design of the actuator drive  12 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A fuel flow pressure regulator in accordance with the present invention has a regulating valve for regulating a flow of fluid such as fuel, which is identified with reference numeral  1 . The regulating valve  1  is arranged on a fuel flow line  2  which extends between a fuel flow inlet  3  and a fuel flow outlet  4 . The function of the regulating valve is to open the fuel line  2  so as to allow a continuous flow on fuel from the fuel flow inlet  3  to the fuel flow outlet  4 , and to close the fuel line  2  so as to prevent the flow of fuel. For this purpose the regulating valve has a valve member formed as a valve pintle  5  and cooperating with a valve seat  6  so as to close and to open the regulating valve. 
   The valve pintle  5  is arranged on one end of a connecting rod  6  with an opposite end connected to an armature  8 . A coil  9  is arranged in a pole piece  10  and, when supplied with electric power, attracts the armature so as to move the valve pintle  5  to an open position. A spring  11  biases the armature  8  upwardly in the drawing, so as to move the valve pintle  5  to the closed position. 
   The regulating valve  1  is a proportional flow valve. It may be of a poppet type, which is the most common type used in automotive pressure regulation. The valve may be either balanced or unbalanced, depending on the required flow rate and minimum and maximum pressure differentials. However, any other mechanical valve may be used in the present invention as well. 
   The electronic signal is supplied to the coil  9  by an actuator driver  12 . The electromagnetic actuator is a high efficiency actuator and sends electronic signals to the coil of the regulating valve to provide a corresponding operation of the regulating valve, in particular for changing the opening degree of the regulating valve  1 . The actuator driver  12  is connected with control means  13  and receives control signals from the control means. 
   The control means  13  represent an electronic controller which operates depending on corresponding parameters. It may be formed as an analog and/or a digital controller, depending on performance, size and cost targets. It can include also safety monitoring and protection features. 
   The fuel flow pressure regulator in accordance with the present invention further has a high pressure sensor identified with reference numeral  14  and a low pressure sensor identified with reference numeral  15 . The high pressure sensor  14  is connected with the fuel flow line  2  at the side of the inlet  3 , while the low pressure sensor  15  is connected with the fuel flow line  2  at the side of its outlet  4 , so as to sense the pressure of the fuel flowing to the regulating valve  1  and the pressure of the fuel discharged from the regulating valve  1 . The outlets of the high pressure sensor  14  and the low pressure sensor  15  are connected to the control means  13 . Means are further provided for supplying to the control means  13  a signal corresponding to a set point pressure, as identified with reference numeral  16 . 
   In operation of the regulator in accordance with the present invention, a signal corresponding to the outlet pressure measured by the low pressure sensor  15  and a signal corresponding to the set point pressure are supplied to the control means  13  and compared in it. Based on this comparison, a signal is supplied by the control means  13  to the electromagnetic actuator  12 , which in turn supplies a corresponding electronic signal to the regulating valve  1  and controls the latter respectively, for adjusting a degree of opening of the regulating valve  1 . In order to maximize the performance of the regulator and minimize the possibility of instability, a signal corresponding to the inlet pressure sensed by the high pressure sensor  14  can be also supplied to the control means  13 . 
   In accordance with still a further feature of the present invention means are provided for sensing an exact position of the pintle  5  of the regulating valve  1  and supplying a corresponding signal to the control means  13 . This means can be formed as a displacement sensing transducer  17  which is connected to the control means  13  and supplies its signal to the latter. The control means  13  therefore takes into consideration the position of the pintle  5 , by sensing the position of the rod  7  which holds the pintle  5 , for thereafter correspondingly controlling the opening degree of the regulating valve  1 . This can be used for more accurate pressure control (less overshoot or undershoot), fast response and wear compensation, as well as enhanced self diagnostic capability. This feature allows detection of oscillation or other undesirable operating modes, and allows active correction of them by an on-board controller. 
   The fuel flow pressure regulator in accordance with the present invention further has a high pressure shut off valve identified with reference numeral  18 . The high pressure shutoff valve is used for shutting off the regulating valve and preventing excessive wear and tear of the latter. In the event of a high pressure a diagnostic monitor  19  sends a signal to the high pressure shut off valve  18 , and a latter reverts the pintle  5  of the regulating valve  1  to its closed position, with a bubble-tight seal because of significant spring biasing. 
   The fuel flow regulator further has a pressure relief valve which is identified with reference numeral  20 . The pressure relief valve  20  is connected with the control means  13 , so that when the control means  13  detect a release of the pressure relief valve it stores data related thereto and sets a diagnostic mode with the use of the diagnostic monitor  19  and also alerts the driver through a diagnostic information line  21  alerting the driver through a check engine light. The pressure relief valve is used in case of malfunctions of the regulating valve  1  or the control means  13 , to simply vent high-pressure gas to the atmosphere. 
   All of the sensor signals in the inventive fuel flow regulator can be monitored by the engine management unit and/or diagnostic tools. 
   In medium to high flow operations, the regulating valve can operate in a throttling mode when the valve does not close at all. This is the most desirable operating mode as it reduces wear of the valve assembly. During low flow operation, the valve may not be able to throttle the gas sufficiently and the regulator valve will oscillate just around the shut off point of the valve transfer function. Due to the non linear nature of the valve at this point, the valve will operate in a limit-cycle oscillation mode. 
     FIG. 3  illustrates a basic pressure regulator control loop. The outlet pressure signal generated by the pressure sensor  15  is subtracted from the said point pressure (desired outlet pressure)  19 . This signal is then fed to a feedback control block. This block can be one or several types of feedback control blocks used and known in the art. The commonly used proportional-integral-derivative block will be used in this example; however, it is only an exemplary embodiment. This block operates by applying a part of the input error signal E to the control output signal U via a variable gain block K P . This signal is fed to a summing block S. The variable gain block acts to multiply the signal going through it. Another part of the feedback blocks applies the input error signal E through a variable gain block K l  and an integrator. The output of the integrator moves in the direction and speed of the input block, performing a real-time operation of a mathematical integration with respect to time. The output of the integrator is applied to the output signal U via the summing block S. The third part of this standard control block is a differentiator which works by taking a time derivative of the signal (or the rate of change of the signal) and applying it through another gain stage K d . This signal is fed to the output signal U via the summing block S. 
   The pressure signal generated by the pressure sensor  15  is monitored for performance. There are several ways of doing this, but a common method involves taking the square of the error signal E from the above block and integrating it via the same logic as used in the above block. This integrating signal can be used to determine if the regulator is responding too slowly or too quickly. A regulator that responds too quickly will tend to oscillate, resulting in excessive noise and wear of the metering valve  1 . The performance adjustment would automatically reduce the gains K d  and K p  via another integrator. The output of this integrator is scaled by a gain adjustment factor K a . Direction information is determined from the error direction. If the error is constantly low, the gains should be increased as shown in FIG.  4 . If the error is jumping from high to low and back again, the gains should be decreased as shown in FIG.  5 . If the error can not be controlled, then the safety monitoring device  19  will force the metering valve  1  closed, and the optional redundant safety valve  18  is closed. 
   As the inlet pressure can vary, the amount of valve opening required to correct a specific pressure error will also vary. Normally, the amount of required opening increases with a decreasing pressure. This can cause control loop instability in a high inlet pressure condition which can be predicted from this design, and also observed in mechanical pressure regulators which are used currently in the art. The preferred embodiment of this is a calibrated function that utilizes the inlet pressure sensor  14  and its signal to modify the games K D , K p  and K l . These adjustments are made by multiplying the existing gains calculated as in the preceding paragraph. 
   It should be mentioned that the actuator driver  12  is simply a power amplifier that is used to interface the control output of the control system  13  to the electromagnetic coil  9  of the actuator. A typical design is shown in FIG.  6 . This is only an exemplary embodiment, and of course it can be designed differently as well. 
   Since the inventive regulator is operative for performing many functions electronically, external electronic modules can interface with the regulator. Said points and gain adjustments described herein above can be communicated from an engine control module to the regulator control system  13  and the regulator setpoint input  16 . Also, performance adjustments described herein above, may be communicated to the engine control module and used for internal calculations of the engine controller and also to inform the driver of a problem or potential problem that may need to be repaired. This is another important feature of the present invention that is a part of the preferred embodiment, namely the integration with existing engine control systems. 
   It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
   While the invention has been illustrated and described as embodied in electromagnetic valve for regulation of a fuel flow, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
   Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
   What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.