System and method for actuating an ignition coil

Abstract

The present invention relates to a system and method for actuating an ignition coil that acts on the actuation time, independently of the supply voltage of the battery of the vehicle system, preventing damage and optimizing coil use. The electronics of said system and method make it possible for the actuation time to be inversely proportional to the voltage value, without limiting operating time, even when there is a voltage drop following use of the starter motor, allowing the ignition system to be used in automotive systems that use different low-combustion fuels, as well as different sizes of battery, thus simplifying application thereof.

Description

"SYSTEM AND METHOD OF DRIVE FOR IGNITION COIL" Field of Invention

[0001] The present invention relates to a system and method for actuating an ignition coil that operates during the activation time, independent of the system's battery voltage, preventing damage and optimizing coil usage.

[0002] The aforementioned system and method, through its electronics, allows the activation time to be inversely proportional to the voltage value, not limiting the operating time, thus enabling the use of the ignition system in automotive systems that use different types of fuels (with low combustion) and different battery sizes, simplifying its application. Fundamentals of the Invention

[0003] As is well known, the ignition coil is an automotive part used in combustion engines. It is responsible for generating sufficient voltage for the engine to ignite through sparking between the electrodes of a spark plug.

[0004] The ignition coil is located near the engine cylinder and is powered by the vehicle's battery voltage, being controlled by a direct current signal from an engine control unit (commonly called by the acronym ECU for "Electronic Control Unit"). From this command signal, the electronic circuit in the ignition coil must be able to perform its primary function of activating the primary winding of the ignition coil transformer, but it should not be limited to just that, and may have some secondary protection functions.

[0005] One of the secondary protections of the ignition coil is the so-called "shutdown time". Under normal operating conditions, the duration of the control signal is usually on the order of milliseconds, this time being responsible for charging the magnetic circuit through the circulation of current in the primary winding. However, it is possible that there may be some anomalies in the system (such as short circuits between conductors in the vehicle's wiring harness, calibration errors, failure in the ECU control program, among others) causing the duration of this signal to vary. The signal exceeds the desired duration by a significant amount of time, causing damage to the electronic components and / or the primary winding of the transformer and, in more serious cases, even a critical product failure.

[0006] To prevent such damage, a shutdown time protection function is incorporated into the ignition coil, with the purpose of interrupting the flow of electric current in the primary winding, to prevent the ignition coil from receiving a control signal with a duration much longer than it was designed to operate normally.

[0007] This function is performed by an electronic system that, through the use of a comparison circuit and an ECU command, designs a shutdown time based on resistors and capacitors, using a fixed supply voltage provided from a digital power supply for the vehicle's system (commonly 5 V). For variable times depending on the size and type of vehicle, it is necessary to calculate and customize the shutdown time protection.

[0008] Patent document JP60116863 describes a method for improving the ignition performance of an engine by detecting the time required for the primary current of an ignition coil to rise to a normal current level using an arithmetic unit of engine starting time and correcting the primary current supply period according to the deviation between the aforementioned rise time and the reference rise time.This solution uses an arithmetic unit that signals various engine operating parameters, such as engine turning angle, battery voltage, and primary current supply to an ignition coil, controlled by a power transistor and a conduction signal obtained from the arithmetic unit. A resistor is connected directly to the collector-emitter circuit of the transistor, and a primary current detection signal is produced at a connection point where a resistor is connected to the collector-emitter circuit of the transistor. By comparing the primary current detection signal with a normal current level signal produced at a connection point where the resistors are connected, a signal is obtained that... This represents the point in time when the primary current is raised to a normal current level and is used in the arithmetic unit to correct the primary current supply period. Therefore, this solution requires an additional arithmetic unit to perform the primary current detection necessary for the ignition coil, increasing the cost of the supplied circuit and thus making it a more complex and expensive solution.

[0009] Based on this scenario, and aiming to mitigate the technical limitations observed in the presented patent document, the present invention arises. Objectives of the Invention

[0010] Thus, the main objective of the present invention is to disclose a system and method for actuating an ignition coil that operates during the actuation time, independent of the digital system's supply voltage, but dependent on the vehicle's battery voltage.

[0011] Additionally, the present invention aims to provide a system and method for actuating an ignition coil that operates independently of the digital supply voltage, in order to optimize and protect the coil.

[0012] Furthermore, the present invention aims to disclose a system that, through its electronics, allows the maximum activation time (or shutdown time) to be inversely proportional to the battery voltage value, not limiting the operating time, thus enabling the use of ignition coils in automotive systems that use different types of fuels (with low combustion) and different battery voltage values ​​(and also when there is a voltage drop during starting), thereby simplifying its application.

[0013] Furthermore, the objective of the present invention is to present an ignition coil drive system that, through its electronics, delays the shutdown time due to low temperatures. Summary of the Invention

[0014] All the aforementioned objectives are achieved through the ignition coil drive system, which comprises: at least one control unit, at least one interface with the coil transformer. ignition, at least one comparator block where there is a supply voltage associated with at least one comparator unit and a charging voltage associated with a battery voltage and at least one control circuit related to at least one control unit.

[0015] Additionally, in the ignition coil drive system, it is also understood that the comparator unit associated with a supply voltage consists of at least one positive differential input and at least one negative differential input.

[0016] Furthermore, the ignition coil drive system includes the fact that the comparator unit has a voltage divider circuit associated with one of the differential inputs, consisting of at least one resistor and connected to the supply voltage.

[0017] Furthermore, the ignition coil drive system comprises the fact that the comparator unit has associated with one of the differential inputs a fixed reference voltage circuit and a supply voltage.

[0018] Additionally, the ignition coil drive system also includes the fact that the comparator unit has a timer circuit associated with one of the differential inputs, which is also connected to the drive output of the control unit and to a charging voltage equal to the battery voltage.

[0019] Furthermore, the ignition coil drive system comprises the fact that the timer circuit associated with the differential input of the comparator unit is an RC timer circuit comprising at least one resistor and at least one capacitor, also associated with a charging voltage equal to the battery voltage.

[0020] Also, the ignition coil drive system comprises the fact that the timer circuit associated with the differential input of the comparator unit is an RC timer circuit comprising at least one resistor and at least one capacitor, associated with a thermistor and a charging voltage equal to the battery voltage.

[0021] Furthermore, the ignition coil drive system includes the fact that the comparator unit is a comparator integrated circuit.

[0022] Additionally, a drive method for the ignition coil is proposed, comprising the following steps: issuing a start command from the activation of at least one control unit, activating at least one interface with the ignition coil transformer from a timer block, which is activated by the control unit and operates for a defined time based on the battery voltage level of the automotive system.

[0023] Finally, the ignition coil actuation method includes the fact that the timer block also operates based on ambient temperature. Brief Description of the Figures

[0024] The preferred embodiment of the invention in question is described in detail based on the listed figures, which:

[0025] Figure 1 illustrates, in block diagram form, the system and actuation method for the ignition coil.

[0026] Figure 2 illustrates a circuit topology of the comparator block in an ignition coil drive system.

[0027] Figure 3 illustrates a circuit of the temperature-dependent comparator block in a drive system for an ignition coil. Detailed Description of the Invention

[0028] According to the general objectives of the invention in question, the ignition coil drive system comprises: at least one control unit 1, at least one interface with the ignition coil transformer 2, at least one comparator block 3, in which there is a supply voltage Vdd associated with the power supply of at least one comparator unit Cl COMP and a charging voltage Vcar associated with the battery voltage +BATT and at least one control circuit related to at least one control unit 1.

[0029] Figure 1 illustrates, in block diagram form, the drive system for the ignition coil. Block 1 represents a control unit 1, commonly called an ECU (“Electronic Control Unit”) in automotive systems or any other automotive or other automotive applications. A processing unit equipped with memory and interfaces sends the command to activate ignition coil 2, represented by block 2, and, intermediately, block 3, as comparator block 3. The supply voltage Vdd of ignition coil 2 is provided by the power supply of the system circuits (commonly 5V, 12V or 24V), and the charging voltage Vcar that powers the comparator block comes from one of the poles of the automotive system battery, indicated by +BATT in the diagram (as the positive signal of the battery), but which in alternative circuit topologies could be the negative.

[0030] Thus, the ignition coil drive system also includes the fact that the comparator unit Cl COMP, associated with a supply voltage Vdd, is composed of at least one positive differential input “+” and at least one negative differential input. The Cl COMP, located in comparator block 3, is a circuit with a topology that performs a comparison between two references, and can be a circuit formed by an operational amplifier (op amp) or an integrated circuit with the same function.

[0031] Furthermore, the ignition coil drive system comprises the fact that the comparator unit Cl COMP has associated with one of its differential inputs a voltage divider circuit formed by at least one resistor R1.1 and associated with the supply voltage Vdd. Thus, one of its differential inputs (positive + or negative -) serves as a reference for the comparator circuit, which is formed by a circuit that provides a fixed voltage, read on a resistor R1.1.

[0032] Furthermore, the ignition coil drive system comprises the fact that the comparator unit Cl COMP has associated with one of the differential inputs a fixed reference voltage circuit and a supply voltage Vdd, being any topology that provides a fixed voltage.

[0033] Furthermore, the ignition coil drive system also includes the fact that the comparator unit Cl COMP has associated with one of the differential inputs a timer circuit also associated with the drive command output of control unit 1 and a charging voltage Vcar equal The battery voltage +BATT. Responsible for controlling the ignition coil from the ignition coil transformer 3, this circuit topology sends commands from the control unit 1 and is associated with a charging voltage Vcar, which in the case of the system proposed here, is the battery voltage +BATT, which will influence the maximum activation time (or deactivation time) depending on the timer circuit topology used.

[0034] Thus, the ignition coil drive system is understood by the fact that the timer circuit associated with the differential input of the comparator unit Cl COMP is an RC timer circuit comprising at least one resistor (R3) and at least one capacitor C, or an equivalent voltage-time modulation circuit, also associated with a charging voltage (Vcar) equal to the battery voltage (+BATT). In this way, depending on the design, the values ​​of resistance R3 and capacitance C are fixed.

[0035] Figure 2 illustrates a circuit topology of comparator block 3 in an ignition coil drive system, where it is associated with the negative differential input. a voltage divider circuit associated with the voltage Vdd, composed of a resistor R1.1 and a resistor R1.2, and associated with the positive differential input “+” a drive topology circuit associated with the charging voltage Vcar (associated with +BATT) composed of a timer circuit (resistor R3 and capacitor C) and the transistor Q in series with resistors R2 and R4, associated with control unit 1.

[0036] In a system that uses a charging voltage Vcar equal to the supply voltage Vdd, commonly used for this type of application, the transistor Q, upon receiving the command signal, stops conducting and allows the capacitor C to charge through the current flowing through R, originating from a fixed DC voltage associated with Vdd. Resistors R1.1 and R1.2 form a resistive divider whose function is to provide a fixed voltage to be compared by the comparator integrated circuit, which uses Vc as a reference for comparison with the capacitor's charging voltage. Knowing that the capacitor charging time is given by:

[0037] A combination of R1.1 and R1.2 is chosen such that the comparator trigger voltage Vc is:

[0038] Therefore, substituting the equations, we have that the shutdown time, toff, is:

[0039] Therefore, a combination of R3 and C is chosen in such a way that it results in the desired shutdown time. Upon reaching the shutdown time, the comparator integrated circuit inhibits the flow of electric current at the ignition coil switching interface, inhibiting the flow of current in the primary winding, ultimately protecting the electronic components and the primary winding of the transformer.

[0040] After the interruption of the command signal, transistor Q conducts again, leading to a discharge of capacitor C through resistor R2, thus enabling C for a new charge and consequent action of the turn-off time function, if necessary. As can be observed from the topology and previous equations, the charging voltage of capacitor C is fixed and comes from a voltage regulator, resulting in a fixed turn-off time as well.

[0041] Thus, in the ignition coil drive system proposed here, when using a charging voltage Vcar equal to the battery voltage +BATT, without additional adjustment and varying depending on vehicle conditions, the equation becomes:

[0042] Therefore, the shutdown time is now a function of the battery supply voltage, rather than a fixed value. The higher the battery supply voltage +BATT, the greater the electrical current charging capacitor C, which charges faster, thus reaching the comparison point more quickly, resulting in a shorter shutdown time. Similarly, the lower the battery voltage +BATT, which can vary depending on vehicle use or successive attempts, the longer the shutdown time will be; that is, the ignition coil 2 transformer will remain on for longer, forcing the vehicle to start.This function becomes interesting for application in vehicles that have more difficulty with combustion, for example ethanol and other biofuels, where different vehicles may use different types of battery voltage (12V, 24V or alternative voltages), resulting in a simple system that works for various systems. When the driver turns the key to start the engine, the starter motor engages, consuming considerable energy and causing a drop in battery voltage, thus requiring the ignition coil 2 transformer to remain on for a longer time. Therefore, the present invention assists in these voltage drop moments because, for low battery voltages, it will allow for a longer activation time, not limiting the system.In heavy vehicles, unlike the commonly used diesel (which is easily combustible), the use of alternative fuels requires greater control over the ignition coil transformer's connection time.

[0043] Furthermore, the present invention of the drive system for the coil of The ignition timing circuit, as understood, is an RC timer circuit associated with the differential input of the comparator unit Cl COMP. This circuit consists of at least one resistor R3 and at least one capacitor C, connected to an NTC thermistor and a charging voltage Vcar equal to the battery voltage +BATT. The NTC thermistor, which has a negative coefficient, acts as a resistor whose resistance is inversely proportional to temperature; that is, the hotter the temperature, the lower the resistance. Connecting it in series with resistor R3 and capacitor C delays the shutdown time at colder temperatures due to the increased equivalent resistance to charging of the capacitor (resistor R3 in series with the NTC thermistor), and reduces the shutdown time at higher temperatures due to the decreased equivalent resistance to charging of the capacitor (resistor R3 in series with the NTC thermistor).

[0044] In this way, with this circuit topology, there is greater protection when dealing with high temperatures, where there is a greater probability of system damage due to the shorter shutdown time, without limiting operation at low temperatures, due to the use of the NTC thermistor.

[0045] Figure 3 illustrates a temperature-dependent comparator block circuit in an ignition coil drive system, where it is associated with the negative differential input. A voltage divider circuit associated with the voltage Vdd, consisting of a resistor R1.1 and a resistor R1.2, and associated with the positive differential input “+”, a drive topology circuit associated with the charging voltage Vcar (associated with +BATT) consisting of a timer circuit consisting of resistor R3 and an NTC thermistor, in addition to capacitor C, and also transistor Q in series with resistors R2 and R4, associated with control unit 1.

[0046] Furthermore, the ignition coil drive system includes the fact that the Cl COMP comparator unit is a comparator integrated circuit, which has a topology in its encapsulation that allows the use of a comparator circuit in an easy and compact way for use in the application circuit.

[0047] Furthermore, a drive method for a coil system is proposed. ignition system comprising the steps of: issuing a start command from the activation of at least one control unit 1, activating at least one interface with the ignition coil transformer 2 from a timer block 3, where the timer block 3 activated by the control unit 1 operates with a time defined as a function of the battery voltage level +BATT.

[0048] Finally, the actuation method for the ignition coil system involves the fact that the timer block 3 also operates according to the ambient temperature. For high temperatures, the timer block 3 acts to reduce the actuation time of the ignition coil transformer 2, and acts in the opposite way if the ambient temperature is milder or colder, increasing this actuation time.

[0049] In this way, the ignition coil drive system and method reduces the shutdown time at higher battery voltages, which is when there is a greater likelihood of damage to the electronic components and the primary winding of the transformer, allowing for a longer shutdown time at lower battery voltages - not unnecessarily limiting the continuous operation of the product when exposed to this condition of lower probability of damage.

[0050] It is important to emphasize that the description above aims solely to exemplify a particular embodiment of the invention in question. Therefore, it is clear that modifications, variations, and constructive combinations of the elements that perform the same function substantially in the same way to achieve the same results remain within the scope of protection delimited by the appended claims.

Claims

CLAIMS 1. Ignition coil drive system comprising: At least one control unit (1); At least one interface with the ignition coil transformer (2); At least one comparator block (3); CHARACTERIZED by the fact that in the comparator block (3) there is a supply voltage (Vdd) associated with the supply of at least one comparator unit (Cl COMP) and a charging voltage (Vcar) associated with the battery voltage (+BATT) and at least one control circuit related to at least one control unit (1).

2. A drive system for an ignition coil, according to claim 1, CHARACTERIZED in that the comparator unit (Cl COMP) associated with a supply voltage (Vdd) is composed of at least one positive differential input (+) and at least one negative differential input (-).

3. Actuation system for an ignition coil, according to claims 1 and 2, CHARACTERIZED in that the comparator unit (Cl COMP) has associated with one of the differential inputs a voltage divider circuit formed by at least one resistor (R1 .1 ) and associated with the supply voltage (Vdd).

4. Actuation system for an ignition coil, according to claims 1 and 2, CHARACTERIZED in that the comparator unit (Cl COMP) has associated with one of the differential inputs a fixed reference voltage circuit and a supply voltage (Vdd).

5. Actuation system for ignition coil, according to claims 1 and 2, CHARACTERIZED in that the comparator unit (Cl COMP) has associated with one of the differential inputs a timer circuit also associated with the actuation command output of the control unit (1) and a charging voltage (Vcar) equal to the battery voltage (+BATT).

6. Actuation system for ignition coil, according to claims 1, 2 and 5, CHARACTERIZED in that the timer circuit associated with the differential input of the comparator unit (Cl COMP) is a timer circuit. RC comprised of at least one resistor (R3) and at least one capacitor (C), also associated with a charging voltage (Vcar) equal to the battery voltage (+BATT).

7. Actuation system for an ignition coil, according to claims 1, 2 and 5, CHARACTERIZED in that the timer circuit associated with the differential input of the comparator unit (Cl COMP) is an RC timer circuit, comprising at least one resistor (R3) and at least one capacitor (C), associated with a thermistor (NTC) and a charging voltage (Vcar) equal to the battery voltage (+BATT).

8. A drive system for an ignition coil, according to the preceding claims, CHARACTERIZED in that the comparator unit (Cl COMP) is a comparator integrated circuit.

9. Actuation method for an ignition coil comprising the following steps: - issue a start command from the activation of at least one control unit (1); - activate at least one interface with the ignition coil transformer (2) from a timer block (3) CHARACTERIZED by the fact that the timer block (3) activated by the control unit (1) operates with a time defined as a function of the battery voltage level (+BATT).

10. Actuation method for ignition coil, according to claim 9, CHARACTERIZED in that the timer block (3) also operates as a function of ambient temperature.

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