Electronic control unit

Abstract

To provide an electronic control unit capable of not losing rotation angle detection accuracy over low revolution to high revolution for a rotation sensor configured with a high-output electromagnetic pickup and capable of suppressing increases in size and cost of a waveform shaping circuit.SOLUTION: An electronic control unit for performing engine control with combustion control by detecting a rotation angle of an engine with inputting an output signal having an AC voltage waveform from an electromagnetic pickup of a rotation sensor includes: a power limitation circuit for limiting power of the output signal while keeping either the positive voltage side or the negative voltage side of voltage waveform for the output signal from the electromagnetic pickup; a waveform shaping circuit for shaping the output signal whose power is limited by the power limitation circuit; and a rotation angle detection circuit for detecting a rotation angle of the engine from a signal shaped by the waveform shaping circuit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to an electronic control device that detects the rotation angle of an engine and performs engine control including fuel control. [Background technology]

[0002] Electronic control devices used to control internal combustion engines installed in vehicles generally use sensors to detect engine rotation, piston position, cam angle, and other rotational angles, as well as intake air volume, and use these to control the engine's air-fuel ratio and ignition / fuel injection timing. Among these, electromagnetic pickups are often used as rotation sensors for detecting rotation angles such as engine rotation and cam angle.

[0003] An electromagnetic pickup is a generator-type element consisting of a magnet and a coil. It is attached near a magnetic gear on the rotating shaft of an engine and outputs an AC electrical signal according to the rotation speed by detecting changes in the magnetic field that occur when the gear teeth pass by. For example, as shown in Patent Document 1, an electronic control device receives as input a signal output from an electromagnetic pickup, converts this signal using a waveform shaping circuit into a signal suitable for input into a digital logic circuit, and then inputs it into a control controller having a microcomputer or the like, and uses the resulting rotation signal for various controls. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5062908 Summary of the Invention [Problem to be solved by the invention]

[0005] Electronic control devices used to control engines simultaneously control not only ignition timing but also fuel, making it necessary to improve the accuracy of rotation angle detection. To improve rotation angle detection accuracy, it is advantageous to set more reference positions per gear rotation. In recent years, to improve engine control accuracy, it is common to increase the number of teeth on magnetic gears attached to the rotating shaft, enabling more precise angle detection. This increases the power of the output signal from the electromagnetic pickup, and the rated power of waveform shaping circuits also tends to increase. Patent Document 1 describes a method for improving the detection accuracy of a rotation angle detection device with a large number of gear teeth. However, it does not describe any measures to deal with the recent trend of increasing the output of electromagnetic pickup signals due to an increase in the number of gear teeth.

[0006] Depending on the output level of the electromagnetic pickup, measures must be taken to improve the withstand voltage and power resistance of the waveform shaping circuit, and measures to improve the withstand voltage and power resistance of the components used in the waveform shaping circuit will result in an increase in the size and cost of the electronic control device, which will be an issue. A simple solution is to reduce the input voltage from the electromagnetic pickup by dividing the output signal from the electromagnetic pickup using a resistor and inputting the divided signal into a waveform shaping circuit. However, this creates the problem that signal detection becomes impossible when the engine speed is low, such as when starting the engine, and the voltage of the output signal from the electromagnetic pickup is small. Another possible method is to switch this resistance value depending on the rotation speed, but in that case there is a problem that the sudden change in impedance at the time of switching causes fluctuations in the control timing of ignition and fuel injection.

[0007] The present application discloses technology for solving such problems, and aims to provide an electronic control device that does not impair the accuracy of rotation angle detection from low to high rotation speeds, even for a rotation sensor consisting of a high-output electromagnetic pickup with a large number of gear teeth, and that can suppress increases in size and cost of the waveform shaping circuit. [Means for solving the problem]

[0008] The electronic control device according to the present application is an electronic control device that receives an output signal having an AC voltage waveform from an electromagnetic pickup of a rotation sensor, detects the rotation angle of the engine, and performs engine control involving fuel control, and includes a power limiting circuit that limits the power of the output signal while maintaining the voltage waveform of either the positive voltage side or the negative voltage side of the output signal of the electromagnetic pickup, a waveform shaping circuit that shapes the output signal limited by the power limiting circuit, and a rotation angle detection circuit that detects the rotation angle of the engine from the signal shaped by the waveform shaping circuit. The power limiting circuit limits the power of the output signal input to the waveform shaping circuit by cutting a signal waveform greater than a reference voltage at which the voltage of the output signal becomes a positive voltage to the reference voltage while maintaining the voltage waveform on the negative voltage side of the output signal of the electromagnetic pickup. It is something. [Effects of the Invention]

[0009] According to the present invention, the voltage waveform of either the positive voltage side or the negative voltage side of the output signal of the electromagnetic pickup is maintained, so the waveform shaping circuit can accurately input the sensor waveform from the rotation sensor. Furthermore, the power limiting circuit limits the power input to the waveform shaping circuit, preventing increases in size and cost of the waveform shaping circuit. Therefore, the entire electronic control device can be made smaller and less expensive, even for a high-output electromagnetic pickup that requires accurate rotation angle detection. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a circuit diagram showing the overall configuration of an electronic control device according to a first embodiment. [Figure 2] 10 is a signal waveform diagram showing the input (point A) and output (point B) of a waveform shaping circuit in an electronic control device of a comparative example that does not have a power limiting circuit. [Figure 3] 4 is a signal waveform diagram showing the input (point A) and output (point B) of the waveform shaping circuit in the electronic control device according to the first embodiment. FIG. [Figure 4] FIG. 10 is a circuit diagram showing the overall configuration of an electronic control device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiment 1 FIG. 1 is a circuit diagram showing the overall configuration of a first embodiment of an electronic control device of the present invention. 1 operates by receiving power from a battery power supply 2 via power input terminals 2a and 2b. The electronic control unit 1 receives signals from sensors and the like provided in various parts of the engine from input terminal 3a to a control controller 10 via an input circuit 3, and grasps the operating state of the engine. A plurality of such input circuits 3 and input terminals 3a may be provided, one of which is for detecting the rotation angle of the engine.

[0012] The control controller 10 is composed of electronic circuits such as a microcomputer, and processes signals from sensors and the like to grasp the operating state of the engine, and performs precise engine control by controlling the operation of the output circuit 11 according to that state. Specifically, it outputs control signals to engine ignition, fuel injection, actuators, etc. via output terminal 11a.

[0013] The rotation angle of a vehicle engine, a feature of the present application, is detected using an electromagnetic pickup type rotation sensor 4. The rotation sensor 4 is composed of a magnetic gear 5 attached to one end of the engine crankshaft and an electromagnetic pickup 6 attached near a protrusion 5a that forms the teeth of the gear 5. The electronic control unit 1 receives an output signal having an AC voltage waveform generated by the electromagnetic pickup 6 from an input terminal 6a and outputs it to a waveform shaping circuit 8 via a power limiting circuit 7. The waveform shaping circuit 8 converts the output signal from the electromagnetic pickup 6, which has passed through the power limiting circuit 7, into a pulse signal suitable for input to a digital logic circuit and outputs it to a rotation angle detection circuit 9 of a control controller 10. The electronic control unit 1 obtains detection values ​​of the engine rotation speed and rotation angle from this pulse signal using the rotation angle detection circuit 9, determines the control timing and control amount for engine ignition, fuel injection, actuators, etc., and provides control outputs to various parts of the engine, including fuel control.

[0014] The gear 5 of the rotation sensor 4 has multiple protrusions 5a that act as teeth at equal intervals around its periphery, but some of the protrusions 5a are missing. The rotation angle detection circuit 9 detects the rotation angle of the engine crankshaft by using the change in the output signal of the electromagnetic pickup 6 at these missing parts as the reference for the rotation angle. Furthermore, engine control involving fuel control requires precision in detecting the rotation angle, so the size of gear 5 is large and the number of tooth protrusions 5a is increased. As a result, as the engine speed increases, the power of the output signal having an AC voltage waveform generated by electromagnetic pickup 6 increases.

[0015] Figures 2 and 3 illustrate how the signal waveforms at the input (voltage at point A in Figure 1) and output (voltage at point B in Figure 1) of the waveform shaping circuit 8 change with the operation of the power limiting circuit 7. The signal waveform at point A shown in the upper part of Figure 2 is the voltage waveform at point A, which is the output signal of the electromagnetic pickup 6 that is not subject to power limiting. It is an AC electrical signal caused by changes in the magnetic field when the protrusion 5a of the gear 5 passes near the electromagnetic pickup 6. In recent years, electromagnetic pickup signals have tended to have higher output power, and it is not uncommon for the output voltage to reach ±50V. The waveform at point B shown in the lower part of Figure 2 is the output signal of the waveform shaping circuit 8. It is a pulse signal that turns on when the voltage waveform at point A passes through zero voltage, changing from negative to positive.

[0016] On the other hand, the signal waveform at point A shown in the upper part of Figure 3 is the voltage waveform at point A that becomes the output signal of the electromagnetic pickup 6 when the power limiting circuit 7 is installed. The maximum voltage on the positive voltage side of point A is limited to below the reference voltage by the operation of the power limiting circuit 7. This means that the withstand voltage of the waveform shaping circuit 8, which is located downstream of the power limiting circuit 7, can be designed to withstand the reference voltage set by the power limiting circuit 7. Furthermore, the output signal of the waveform shaping circuit 8 at point B shown in the lower part of Figure 3 is the same as the waveform at point B shown in the lower part of Figure 2. This is because the waveform at point A limits the voltage only on the positive voltage side and maintains the voltage waveform on the negative voltage side. This means that the timing of the change in the voltage waveform at point A near the zero voltage crossing, where it changes from negative to positive, is less affected, and the timing of the generation of the pulse signal that becomes the output signal of the waveform shaping circuit 8 is less affected.

[0017] Next, the operation of the power limiting circuit 7 provided in this application will be described. The circuit configuration of the power limiting circuit 7 is shown in FIG. 1. The power limiting circuit 7 includes a backflow prevention diode 7a connected to the positive terminal of the output signal of the electromagnetic pickup 6, a Zener diode 7b connected downstream of the diode 7a, and a switching element 7c connecting the downstream side of the diode 7a to ground. The switching element 7c can be, for example, a MOS-FET (Metal-Oxide-Semiconductor Field Effect Transistor). The gate of the switching element 7c is connected to the Zener diode 7b and a resistor 7d. Note that these circuit configurations may be partially modified as long as they comply with the operating principles described here.

[0018] When a positive voltage is applied from the electromagnetic pickup 6 to the input terminal 6a of the rotation sensor 4 of the electronic control device 1, a forward current flows through the diode 7a. As the voltage continues to rise and exceeds the Zener voltage of the Zener diode 7b, a current flows toward ground via the resistor 7d. When the gate terminal voltage of the switching element 7c exceeds a threshold, the switching element 7c turns on. Because the source of the switching element 7c is connected to ground, the voltage at the input terminal 6a of the rotation sensor drops toward the ground voltage (voltage 0). However, when the voltage falls below the Zener voltage of the Zener diode 7b, the gate voltage of the switching element 7c becomes the ground voltage and turns off. In other words, the voltage at the input terminal 6a is controlled by the Zener voltage of the Zener diode 7b.

[0019] As a result, in an input circuit equipped with a power limiting circuit 7, the voltage waveforms at points A and B will be as shown in Figure 3. The maximum voltage on the positive voltage side at point A is controlled by the power limiting circuit 7 with the Zener voltage of Zener diode 7b, and the voltage waveform is cut so that the voltage does not rise above the reference voltage set by this Zener voltage. As a result, the withstand voltage of the waveform shaping circuit 8 located downstream of the power limiting circuit 7 can be designed to withstand the reference voltage set by the power limiting circuit 7, and there is no need to design it to withstand high voltages that can withstand the maximum voltage of the electromagnetic pickup 6. As a result, although the addition of the power limiting circuit 7 increases the circuit size and cost of the electronic control device 1, lowering the voltage resistance design rank of the waveform shaping circuit 8 is expected to reduce the size and cost of the electronic components used, and overall, it is expected that the electronic control device 1 will be made smaller and less expensive.

[0020] Various types of waveform shaping circuits can be used for the electromagnetic pickup signal input for detecting the rotation angle of an engine. However, the waveform shaping circuit 8 described in this embodiment is designed to use the zero voltage when the sensor output changes from negative to positive as the reference position for detecting the rotation position. In this case, accuracy of the sensor waveform, particularly on the negative voltage side, is required. Therefore, in this application, an example has been shown in which the power limiting circuit 7 is provided as a means for implementing power limiting only on the positive voltage side. However, if, for example, a waveform shaping circuit is employed that uses a rotation angle detection method that places importance on the sensor waveform on the positive voltage side, a power limiting circuit that implements power limiting on the negative voltage side may also be used. As described above, by providing a power limiting circuit 7 that limits the power of the output signal while maintaining the voltage waveform of either the positive or negative voltage side of the output signal of the electromagnetic pickup 6, it is possible to input the sensor waveform obtained from the electromagnetic pickup 6 to the waveform shaping circuit 8 without reducing the input accuracy. Furthermore, because the power input to the waveform shaping circuit 8 is limited, it is possible to prevent the waveform shaping circuit 8 from increasing in size and cost. Furthermore, in engine control involving fuel control, a high-output electromagnetic pickup with high accuracy in detecting rotation angles can be used, which improves the accuracy of engine control in the entire electronic control device and reduces its size and cost.

[0021] Embodiment 2 In the first embodiment, a circuit was described that uses a switching element 7c to release power to ground when the input stage voltage exceeds the reference voltage, but in the second embodiment, a means for further reducing the number of components in the power limiting circuit is shown. For example, as shown in Fig. 4, a new power limiting circuit 12 can be considered that includes a Zener diode 12b connected to the power supply of the control circuit and a backflow prevention diode 12a having one end connected to the positive side of the output signal of the electromagnetic pickup 6 and the other end connected to the Zener diode 12b, and that releases power to the battery power supply 2, which is the power supply for the control circuit.

[0022] In FIG. 4, when the sum of the three voltages of the output signal from the electromagnetic pickup 6, namely (voltage of the battery power supply 2) + (Zener voltage of the Zener diode 12b) + (forward voltage of the diode 12a), exceeds a reference voltage, the power limiting circuit 12 causes a Zener current to flow from the output of the electromagnetic pickup 6 to the battery power supply 2 side, thereby cutting the voltage at the input terminal 6a below the reference voltage. In this way, the power limiting circuit 12 can limit the power at the input stage using fewer components than the power limiting circuit 7 shown in the first embodiment. However, because the configuration involves dissipating power to the voltage side of the battery power supply 2, the reference voltage is dependent on the voltage of the battery power supply 2 and is not uniquely determined, so care must be taken when using it in an environment where the voltage of the battery power supply 2 fluctuates greatly.

[0023] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment. [Explanation of symbols]

[0024] 1 Electronic control device, 2 Battery power supply, 2a, 2b Power supply input terminals, 3 Input circuit, 3a Input terminal, 4 Rotation sensor, 5 Gear, 5a Protrusion, 6 Electromagnetic pickup, 6a Input terminal, 7 Power limiting circuit, 7a Diode, 7b Zener diode, 7c Switching element, 7d Resistor, 8 Waveform shaping circuit, 9 Rotation angle detection circuit, 10 Control controller, 11 Output circuit, 11a Output terminal, 12 Power limiting circuit, 12a Diode, 12b Zener diode.

Claims

1. An electronic control device that detects an engine rotation angle by inputting an output signal having an AC voltage waveform from an electromagnetic pickup of a rotation sensor, and performs engine control including fuel control, a power limiting circuit that limits the power of the output signal from the electromagnetic pickup while maintaining the voltage waveform of either the positive voltage side or the negative voltage side of the output signal; a waveform shaping circuit that shapes the output signal limited by the power limiting circuit; a rotation angle detection circuit that detects the rotation angle of the engine from the signal shaped by the waveform shaping circuit; Equipped with The power limiting circuit limits the power of the output signal input to the waveform shaping circuit by cutting a signal waveform that is greater than a reference voltage at which the voltage of the output signal becomes positive, to the reference voltage, while maintaining the voltage waveform on the negative voltage side of the output signal of the electromagnetic pickup.

2. The power limiting circuit a backflow prevention diode connected to the positive terminal of the output signal of the electromagnetic pickup; a Zener diode connected downstream of the diode; a switching element that connects the downstream side of the diode to the ground side, 2. The electronic control device according to claim 1, wherein when the voltage applied to the Zener diode by the output signal exceeds a Zener voltage, the switching element is activated to cut the signal waveform of the output signal input to the waveform shaping circuit to the reference voltage.

3. The power limiting circuit a Zener diode connected to the power supply of the control circuit; a diode for preventing backflow, one end of which is connected to the positive electrode side of the output signal of the electromagnetic pickup and the other end of which is connected to the Zener diode, 2. The electronic control device according to claim 1, wherein when the sum of the voltage of the output signal, the voltage of the power supply, the forward voltage of the diode, and the Zener voltage of the Zener diode, exceeds a reference voltage, a Zener current flows through the power supply, and the signal waveform of the output signal input to the waveform shaping circuit is cut to the reference voltage.

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