Patent Description:
The technical field relates generally to control techniques for solenoid valves and more particularly to controlling fuel injector valves in an internal combustion engine.

Solenoid actuators for (direct) injection valves and intake valves are operated by controlling the current through its coil (which behaves as a resistive-inductive load) according to a specified current profile. As an example, <FIG> shows a typical current profile that is used to activate a solenoid direct injection valve. The current profile includes various activation phases having different parameter definitions. All of the activation phases of the current profile are run through in sequence based on time or current criteria until the end of activation EOA has been reached. The current profile includes a rise-to peak phase <NUM> in which injector valve current rises to open the injector valve, followed by a hold phase <NUM> in which a regulated current level of the injector valve is less than a current level of the injector valve in the rise-to-peak phase but which holds the injector valve in the open state. The hold phase <NUM> is continued until the control signal NON is de-asserted. The control signal NON defines the start of activation SOA as corresponding to the control signal NON being asserted, and defines the end of activation EOA as corresponding to the control signal NON being de-asserted.

<FIG> illustrates accuracy and repeatability with respect to the end of activation EOA. The term "accuracy" specifies the mean delay between de-asserting the control signal NON and the resulting decay of the injector solenoid current. The term "repeatability" describes the time deviation of the decay from the mean value (i.e., jitter). Due to the systematic nature of the delay, this error may be compensated by adjusting the duration of control signal NON. Since the jitter is random in nature, it cannot be compensated for. Instead, the jitter needs to be reduced or otherwise minimized by design.

Depending on a set of external engine conditions, such as the requested output torque and power of the engine or the rail pressure, the needed fuel mass is changed by varying the activation time of the injector. The activation of the injector is controlled by the main microcontroller with help of the digital control signal NON. The injector will be activated using the specified current profile when the control signal is asserted (in this case, when the control signal NON transitions to a logic low state) and deactivated when the control signal is de-asserted (when the control signal NON transitions to a logic high state).

A significant portion of the activation time tolerance is given by the delay and jitter of the final current phase at the end of the activation EOA. When the control signal NON is de-asserted (e.g., when signal NON transitions from logic low to logic high), all NMOS switches of the power stage driving the injector solenoid are turned off, leading to a fast decaying injector current. Due to a non-ideal power stage, there is a systematic delay between the rising edge of the control signal NON and the decay of the injector current. Furthermore, an inherent stastical variation of the injector current level at the moment of the control signal de-assertion from one activation to the next leads to shot-to-shot timing variation (i.e., jitter) of the current decay. That means that the higher the current ripple during the regulated current hold phase <NUM>, the higher the shot-to-shot variation of the current decay. <FIG> illustrates timing details with respect to the tolerance of the end of activation EOA.

Whereas all systematic errors (e.g., delay) can be compensated by adjusting the duration of the control signal NON, the random, statistical part (e.g., shot-to-shot variation) of the error cannot be counterbalanced. Thus, in order to reduce the shot-to-shot variation, the current ripple should to be reduced or otherwise minimized. On the other hand, reducing the current ripple leads to a higher switching frequency of the NMOS switches and thus to higher switching losses. For design reasons, there is a maximum limit to the power loss and consequently to a reduction of the current ripple.

A dedicated application specific integrated circuit ("ASIC") may be utilized to control the injector valves. As such, the ASIC applies current to the injector solenoid according to the current profile definition based on instructions and commands received from an external processor.

<CIT> shows a method, wherein the method involves flowing of electric current in an injecting valve, whose current profile has a retaining phase divided into two sections. The current profile of latter section is steered or regulated to a lower effective value that is provided at the former section. The effective value of the current is lowered by the former section to the latter section.

<CIT> shows a magnetic valve control unit. The magnetic valve control unit has a capacitor, which is switched from a direct current power supply to a magnetic valve to charge a high voltage in the magnetic valve. A charging section generates high voltage by using an inductive component connected with the direct current power supply. A switching section is controlled when the high voltage lies in the magnetic valve, where another switching section is controlled when the supply voltage lies in the magnetic valve. A control section is provided for controlling the switching sections.

<CIT> provides a system for adjusting a fuel injector drive signal during a fuel injection event wherein the system comprises an engine having a fuel injector, a fuel control module configured to generate control signals corresponding to a desired fueling profile of a fuel injection event, and a fueling profile interface module that outputs drive profile signals to the fuel injector in response to the control signals to cause the fuel injector to deliver an actual fueling profile, wherein the fueling profile interface module changes the drive profile signals during the fuel injection event in response to a parameter signal indicating a characteristic of the actual fueling profile.

<CIT> shows an engine control system and method utilizes a processor and a valve controller in communication with the processor. A valve having a solenoid is in communication with the valve controller. The valve controller is configured to receive a combined selection and control signal from the processor, decode a desired electric current profile encoded in the signal, sense a control code encoded in the signal, and operate the solenoid in accordance with the decoded desired electric current profile in response to sensing the control code.

As such, it is desirable to present a system and method for efficiently controlling actuation of solenoid injector valves. In addition, other desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.

Example embodiments overcome deficiencies in existing control devices for solenoid injector valves. In an example embodiment, a valve controller includes a first input and a first output for coupling to the valve. The valve controller is configured to selectively activate the valve following receipt of a first edge of a first input signal at the first input. The valve activation includes a rise-to-peak phase followed by a hold phase in which a current level of the valve during the hold phase is less than a current level of the valve in the rise-to-peak phase, and an ending-of-activation phase following the hold phase in which current ripple of the valve is less than the current ripple of the valve in the hold phase. The less amount of current ripple in the ending-of-activation phase is achieved by an increased switching frequency of drive transistors in the valve controller.

The valve controller transitions activation of the valve from the hold phase to the ending-of-activation phase following receipt of a second edge of the first input signal at the first input. In an example embodiment, the duration of the ending-of-activation phase is predetermined. The duration of the hold phase is larger than the duration of the ending-of-activation phase. The first edge of the first input signal is a falling edge and the second edge of the first input signal is a rising edge which follows the falling edge. The valve controller transitions activation of the valve from the hold phase to the ending-of-activation phase in response to receipt of a second edge of the first input signal at the first input. The valve includes a fuel injector for a motor vehicle having a combustion engine such that the valve controller controls the fuel injector. The valve controller includes an application specific integrated circuit (ASIC), the ASIC having at least one state machine. The at least one state machine generates a first output signal at the first output for receipt by the valve, which activates the valve in the rise-to-peak phase, the hold phase and the ending-of-activation phase. An amount of jitter of the current valve is less than the amount of jitter of the current valve without the valve being activated in the ending-of-activation phase. A method of controlling a solenoid injector valve includes receiving a first input signal; detecting a first edge of the first input signal; and in response to detecting the first edge of the first input signal, activating the valve. Valve activating includes activating the valve in a rise-to-peak phase during which the valve is opened, a hold phase following the rise-to-peak phase during which the valve remains open and a current level of the valve is less than a current level of the valve during the rise-to-peak phase, and an ending-of-activation phase following the hold phase during which current ripple in the valve is less than the current ripple in the valve during the hold phase.

The method further includes detecting a second edge of the first input signal, wherein activating the valve in the ending-of-activation phase occurs in response to detecting the second edge of the first input signal. The first edge is a falling edge of the first input signal and the second edge of the first input signal is a rising edge thereof. The second edge of the first input signal is the next edge thereof in succession following the first edge of the first input signal.

The method may further include detecting a second edge of the first input signal, wherein activating the valve in the ending-of-activation phase occurs following detecting the second edge of the first input signal. Activating the valve in the ending-of-activation phase occurs over a predetermined period of time. The predetermined period of time is fixed each instance during which the valve is activated. In one aspect, the duration of the hold phase is greater than a duration of the ending-of-activation phase. In another aspect, the duration of the ending-of-activation phase is greater than the duration of the hold phase.

Other advantages of the disclosed subject matter will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:.

Referring to the <FIG>, wherein like numerals indicate like parts throughout the several views, an engine control system and method of controlling actuation of a solenoid valve are shown and described herein.

Referring to <FIG>, the engine control system <NUM> of an example embodiment is utilized to control at least one aspect of an engine <NUM> of a vehicle <NUM>. The engine <NUM> may be an internal combustion engine fueled with, for example, a petroleum product such as gasoline or diesel fuel. Of course, those skilled in the art appreciate that other fuels may be utilized with the engine <NUM> and/or that other types of engine <NUM> may be implemented. The vehicle <NUM> may be an automobile, truck, tractor, motorcycle, boat, aircraft, etc., as is readily appreciated by those skilled in the art.

The engine control system <NUM> includes a processor <NUM>. The processor <NUM> is capable of performing calculations, manipulating data, and/or executing instructions, i.e., running a program. The processor <NUM> may be implemented with a microprocessor, microcontroller, application specific integrated circuit ("ASIC"), and/or other device(s) (not shown) as appreciated by those skilled in the art. The processor <NUM> may include a memory (not shown) for storing data and/or instructions as is also appreciated by those skilled in the art. The engine control system <NUM> also includes a valve controller <NUM>. In the example embodiment, the valve controller <NUM> is independent from the processor <NUM> and is implemented with an ASIC. The valve controller <NUM> generates control signals for controlling one or more valves <NUM>. The valve controller <NUM> may include one or more state machines which generate the control signals for the valves <NUM>. However, it should be appreciated that the valve controller <NUM> may be implemented with other devices and/or circuitry as appreciated by those skilled in the art.

The valve controller <NUM> is in communication with the processor <NUM>. As such, instructions and/or data may be sent at least from the processor <NUM> to the valve controller <NUM>, as described in greater detail below.

In the illustrated embodiment, the valve controller <NUM> is also in communication with a plurality of valves <NUM>. As shown in <FIG>, four valves <NUM> are utilized, each in communication with the valve controller <NUM> such that each valve <NUM> is controlled thereby. In this example embodiment, the valves <NUM> are each direct injection valves <NUM> for directly injecting fuel into a cylinder (not shown) of the engine <NUM>. However, it should be appreciated that the valves <NUM> may be other types of fuel valves and/or serve other purposes. For example, one or more of the valves <NUM> may be an intake valve for regulating air and/or fuel flow to the cylinder(s).

In the example embodiment, each valve <NUM> includes a solenoid <NUM> mentioned above. As appreciated by those skilled in the art, the solenoid <NUM> activates and/or actuates the valve <NUM> between positions and/or states, such as an open position and a closed position. That is, the solenoid <NUM> opens the valve to allow fluid, in this case fuel, to flow therethrough and closes the valve to prevent fluid from flowing. The solenoid <NUM> is in communication with the valve controller <NUM>. As such, the valve controller <NUM> may generate one or more output control signals <NUM> and/or other data for controlling activation of each valve <NUM> and/or the solenoid <NUM> thereof. In an example embodiment, each valve <NUM> and/or solenoid <NUM> is controlled by a distinct set of one or more control signals <NUM>. Each control signal <NUM> may be a pair of differential signals.

In an example embodiment, the valve controller <NUM> includes a memory <NUM> for storing, among other things, at least one current profile. A current profile defines the electric current in each solenoid <NUM> and/or valve <NUM> throughout valve activation. <FIG> depicts a current profile <NUM> for each solenoid <NUM> and/or valve <NUM> during valve activation, according to an example embodiment. Similar to the conventional current profile of <FIG>, the current profile includes a rise-to-peak phase <NUM> during which current levels in the solenoid <NUM> are such as to open the corresponding valve <NUM>, and a hold phase <NUM> which follows the rise-to-peak phase <NUM> and during which current levels in the solenoid <NUM> are sized to maintain valve <NUM> in the open position. <FIG> illustrates the amount of current ripple IRHP during this activation phase. According to example embodiments, the current profile <NUM> includes another phase <NUM> which follows the hold phase <NUM> and during which the amount of current ripple IREOA in solenoid <NUM> is reduced compared to the amount of current ripple IRHP during the hold phase <NUM>. The amount of current ripple is reduced by increasing the switching frequency of the drive transistors (not shown) in the valve controller <NUM> for the valve <NUM>. Increasing the switching frequency will lead to greater switching losses in the phase <NUM>. However, by limiting the time duration of this phase <NUM>, the increase in power loss during the phase <NUM> is relatively limited and unappreciable. The phase <NUM> occurs after the hold phase <NUM> and just prior to the end of the activation period for valve <NUM>, and is hereinafter referred to as the ending-of-activation phase <NUM>. In this way, the example embodiments effectively separate the hold phase <NUM> from the ending-of-activation phase <NUM> having reduced current ripple IREOA, thereby maintaining no increase in power loss during the hold phase <NUM>.

Valve activation in the rise-to-peak phase <NUM> occurs in response to a triggering and/or asserting edge of control signal <NUM>, which in the embodiment illustrate in <FIG> and <FIG> is the falling edge of control signal <NUM>. In addition, valve activation transitions from the hold phase <NUM> to the ending-of-activation phase <NUM> following and in response to a rising (de-asserting) edge of control signal <NUM> which follows the above-identified falling edge thereof.

In an example embodiment, ending-of-activation phase <NUM> has a time duration that is fixed at a predetermined amount such that the time duration of the ending-of-activation phase <NUM> in each instance of valve activation is the same. In an example embodiment, the valve controller <NUM> is implemented as or otherwise includes a state machine having timing circuitry for, among other things, setting the time duration of the ending-of-activation phase <NUM>.

<FIG> illustrates that as a result of the reduced current ripple IREOA in a valve <NUM> during the ending-of-activation phase <NUM>, relative to the amount current ripple IRHP during the corresponding hold phase <NUM>, the amount of jitter JEOA following the ending-of-activation phase <NUM> is reduced relative to the amount of jitter JHP seen in existing valve activations of <FIG> which do not include the ending-of-activation phase <NUM>. The reduced jitter JEOA results in valve activation having better accuracy and repeatability. Further, the time delay TDEOA between the end of the ending-of-activation phase <NUM> and the time when current in the valve <NUM> no longer exists is noticeably smaller due to the reduced current ripple IRHP, relative to the time delay TDHP seen in the current profile of <FIG> which does not include an ending-of-activation phase <NUM>.

The valve controller <NUM> described above is configured to execute the method <NUM> of controlling the activation of the solenoids <NUM>, as described below and with reference to <FIG>. However, it should be appreciated that the method <NUM> described herein may be practiced with other devices besides the vehicle <NUM>, engine <NUM>, valve controller <NUM> and engine control system <NUM> described above.

Claim 1:
A valve controller (<NUM>) configured to control a valve having a solenoid, the valve controller (<NUM>) comprising:
a first input and at least one output for coupling to the valve (<NUM>) , the valve controller (<NUM>) configured to selectively activate the valve (<NUM>) following receipt of a first edge of a first signal at the first input, the valve activation including a rise-to-peak phase (<NUM>) followed by a hold phase (<NUM>) in which a current level of the valve (<NUM>) during the hold phase (<NUM>) is less than a current level of the valve (<NUM>) in the rise-to-peak phase (<NUM>), and
an ending-of-activation phase (<NUM>) following the hold phase (<NUM>) in which current ripple (IREOA) of the valve (<NUM>) is less than the current ripple (IRHP) of the valve (<NUM>) in the hold phase (<NUM>), wherein the less amount of current ripple in the ending-of-activation phase is achieved by an increased switching frequency of drive transistors in the valve controller (<NUM>).