JP2015031260A - Solenoid spill valve control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect flyback energy with a simple circuit configuration without requiring special control and a DCDC converter, and to reduce heat loss.SOLUTION: A solenoid spill valve control device includes: a switch (10) for supplying electric current to an upstream side of a solenoid of a solenoid spill valve from a power supply by being turned on; a switch (11) provided in series at a further downstream side than the solenoid (L1) of the solenoid spill valve, and operating the solenoid spill valve by flowing electric current to the solenoid by being turned on, during a drive period during which power is supplied to the solenoid; a diode (12) provided in parallel between the solenoid spill valve and the switch (11), and preventing backflow to the solenoid spill valve side: and a capacitor (13) provided at the downstream side of the diode (12), and collecting flyback energy of the solenoid occurring accompanying the turning-off of the switch (11). The downstream side of the capacitor (13) is connected with the same potential as the power supply.

Description

  The present invention relates to a drive circuit for driving a spill valve in a high-pressure pump, in particular, an electromagnetic spill valve in a high-pressure pump used in a direct injection engine system.

  For the purpose of reducing exhaust gas and improving fuel efficiency, the development and commercialization of gasoline engine vehicles equipped with an in-cylinder injection engine system have been promoted. The in-cylinder injection engine system directly injects high-pressure fuel into the combustion chamber of the cylinder, and has the advantages that the air-fuel ratio is easier to adjust and the compression ratio is easier to increase than the conventional port injection.

  FIG. 1 shows a schematic diagram of a cylinder injection engine system. As shown in FIG. 1, in the cylinder injection engine system 1, the electromagnetic valve 103 in the high-pressure pump 102 is opened by a command from the electromagnetic spill valve drive circuit 106 in the ECU 100. When the solenoid valve 103 is opened, fuel enters the high-pressure pump 102 from the fuel tank 101 through the solenoid valve 103. Then, the camshaft 104 is rotationally driven using the rotational energy of the engine (not shown), whereby the piston 108 is pushed and the fuel pressure in the high-pressure pump 102 is increased. High-pressure fuel passes through the delivery pipe 109 and is supplied to the injector 105. Injector 105 injects the supplied high-pressure fuel into the cylinder in response to a command from injector drive circuit 107. The solenoid valve 103 needs to supply lost fuel every time each injector 105 injects. For this reason, the electromagnetic spill valve drive circuit 106 is operated more frequently than the injector drive circuit 107 that drives each injector 105 (multiple times the number of cylinders of the injector 105), and the thermal establishment is severer than the injector 105.

  Next, a configuration example of the electromagnetic spill valve drive circuit of the cylinder injection engine system will be described with reference to FIG.

  In FIG. 2, the operation is as follows. First, based on control from the control circuit 201 constituted by a CPU and a memory, for example, a switch 211 and a switch 212, which are transistors such as FETs, are turned on, and a load 221 of an electromagnetic valve that is an inductive load, resistance A battery voltage is supplied to R1 to pass a current. The current flowing through the resistor R1 is detected by the current detection circuit 223. When a current sufficient to open the solenoid valve flows into the load 221, the control circuit 201 performs constant current control in which the switch 211 is repeatedly turned on and off. By this control, the valve open state is maintained. Then, the switches 211 and 212 are turned OFF based on the control from the control circuit 201, whereby the current of the load 221 is cut off and the electromagnetic valve is closed.

  Here, when the solenoid valve is closed, a surge voltage is generated in the switch 212 because the solenoid valve 221, which is an inductive load, keeps flowing current. Therefore, the active clamp circuit 222 provided in parallel with the switch 212 cuts off the current while controlling the surge voltage to be a certain voltage or less. However, in this configuration, since the flyback energy of the solenoid valve is dissipated as heat loss by the switch 212 when the valve is closed, countermeasures against heat loss in the switch 212 become a problem.

  Here, as a countermeasure against heat due to surge, a method is known in which, in an injector drive circuit, flyback energy at the time of valve closing is collected in a high voltage capacitor for driving the injector and reused at the next valve opening. (For example, see Patent Document 1)

JP 2008-63993 A

  However, Patent Document 1 adopts a configuration in which flyback energy is recovered by a high voltage capacitor for driving an injector, and if this configuration is simply applied to an electromagnetic spill valve, the circuit configuration becomes complicated. is there. Further, the control is complicated, such as the need for cooperative control between the energy recovery circuit and the DCDC converter for the high voltage capacitor. Complicated control leads to an increase in the calculation load of the CPU, which is not desirable in an engine ECU that requires hard real-time processing.

  The present invention has been made to solve the conventional problems, and does not require special control or a DCDC converter, and can recover flyback energy with a simple circuit configuration and a small number of parts to reduce heat loss. An object of the present invention is to provide an electromagnetic spill valve control device.

  In order to achieve the above object, the electromagnetic spill valve control device of the present invention includes energy recovery means for recovering solenoid flyback energy generated when the second switching element is turned off, and the downstream side of the energy recovery means is a power source. It was characterized by being connected to the same potential.

  According to the electromagnetic spill valve control device of the present invention, it is possible to recover flyback energy and reduce heat loss with a simple circuit configuration without requiring special control or a DCDC converter.

Schematic diagram of in-cylinder injection engine system The figure explaining the structural example of the electromagnetic spill valve drive circuit of a cylinder injection engine system Circuit diagram of electromagnetic spill valve control device in this embodiment

  Hereinafter, an electromagnetic spill valve control apparatus according to an embodiment of the present invention will be described with reference to FIG.

  The electromagnetic spill valve control device shown in the circuit diagram of FIG. 3 corresponds to the electromagnetic spill valve drive circuit of FIG. In FIG. 3, ON / OFF control of the switches 10, 11, and 14 which are transistors such as FETs is performed by a command from a control circuit (not shown) (corresponding to the control circuit 201 in FIG. 2). First, as the valve opening control of the electromagnetic spill valve, the switch 10 and the switch 11 are turned on. As a result, the battery voltage is supplied from the power source + B to the solenoid R1 of the electromagnetic spill valve, which is an inductive load, and the resistor R connected in series between the switch 11 and the ground GND, and a current flows. Diodes D2 and D3 that prevent backflow to the power source + B side are connected in series between the solenoid L1 and the switch 10 and between the solenoid L1 and the switch 11, respectively.

When a current sufficient to open the solenoid valve flows to the solenoid L1 of the solenoid spill valve, constant current control is performed in which the switch 10 is repeatedly turned on and off. By this control, the valve open state is maintained. A flywheel diode D4 is provided between the solenoid L1 and the diodes D2 and D3, and an induced electromotive force generated in the solenoid L1 when the switch 10 is turned off flows through the ground GND. When the switch 10 is turned off, at least the switch 14 is also turned off in synchronization. As a result, it is possible to prevent the energy stored in the capacitor 13 from being lowered. Note that when the switch 10 is ON, the switch 14 does not necessarily have to be turned ON synchronously. However, when the switch 10 is turned ON synchronously, the control of the switches 10 and 14 can be facilitated.

  When the electromagnetic spill valve is closed, the switches 10 and 11 are turned off. As a result, the current to the solenoid L1 is cut off, and the electromagnetic spill valve is closed. When the electromagnetic spill valve is closed, the solenoid L1, which is an inductive load, tries to keep current flowing. Here, a diode 12 is provided in parallel between the solenoid L1 and the switch 11 to prevent backflow of the electromagnetic spill valve to the solenoid L1 side. The capacitor 13 is provided on the downstream side of the diode 12 and collects the flyback energy of the solenoid L1 generated when the switches 10 and 11 are turned off. Thereby, the heat loss due to the surge voltage in the switch 11 can be reduced. Further, the switch 14 is also turned OFF in synchronization with the switches 10 and 11.

  Since the electromagnetic spill valve does not require a high voltage like an injector for opening the valve, it can be driven with the power supply voltage + B. Therefore, it is not necessary to provide a booster circuit such as a DCDC converter, and voltage control related to it is not necessary. On the other hand, in the conventional circuit configuration, the valve closing time can be controlled by the constant voltage control by the DCDC converter, but in the present embodiment, the valve closing time needs to be set by the capacitance value of the capacitor 13. The capacitance value of the capacitor 13 needs to be selected according to the value according to the inductance (L) of the solenoid L1 of the electromagnetic spill valve and the desired cutoff time (T). Here, if the capacitance value of the capacitor 13 is increased too much, the current cutoff time of the solenoid valve is deteriorated. Assuming that the inductance (L) of the electromagnetic spill valve is several mH and the cutoff time (T) is several hundred μsec, it is sufficient that the capacity (C) of the capacitor 13 for absorbing the flyback energy is at most several tens μF from the relationship of the following equation. is there.

  Here, as the capacitor 13 having a capacitance of several tens of μF, a ceramic capacitor is optimal from the viewpoint of ESR, ripple current resistance, and life. Further, in a nonpolar ceramic capacitor, the voltage between terminals of the ceramic capacitor can be relaxed by connecting the negative electrode to other than the ground GND (here, the power supply voltage + B), and the capacity reduction due to the DC bias effect can be suppressed. Thereby, since the capacity of the ceramic capacitor can be saved, the number of parts of the high voltage ceramic capacitor which is a relatively expensive part can be reduced.

  After the energy recovery, the energy stored in the capacitor 13 by the flyback energy of the solenoid L1 is reused as the opening energy when the electromagnetic spill valve is opened next time. When the switch 14 provided on the upstream side of the capacitor 13 is turned on in synchronization with the switch 10 being turned on, the current based on the energy recovered by the capacitor 13 is first supplied to the upstream side of the solenoid L1 of the electromagnetic spill valve. Is done. When the energy stored in the capacitor 13 has been released, a current based on the power supply voltage + B is supplied from the switch 10.

  As described above, according to the electromagnetic spill valve control device of this embodiment, it is possible to recover flyback energy and reduce heat loss with a simple circuit configuration without requiring special control or a DCDC converter.

The electromagnetic spill valve control device according to the present invention is useful as a drive circuit for driving an electromagnetic spill valve in a high-pressure pump, particularly an electromagnetic spill valve in a high-pressure pump used in a direct injection engine system.

10, 11, 14 Switch 12 Diode 13 Capacitor L1 Solenoid

Claims (4)

A first switching means (10) connected to a power source and supplying current to the upstream side of the solenoid (L1) of the electromagnetic spill valve from the power source by turning on;
Second switching is provided in series downstream of the solenoid of the electromagnetic spill valve, and is turned on during a drive period in which the solenoid is energized, thereby causing the solenoid to pass current and actuate the electromagnetic spill valve. Means (11);
Backflow prevention means (12) provided in parallel between the electromagnetic spill valve and the second switching means for preventing backflow to the electromagnetic spill valve side;
An energy recovery means (13) provided downstream of the backflow prevention means, for recovering the flyback energy of the solenoid that is generated when the second switching element is turned off;
The electromagnetic spill valve control device, wherein the downstream side of the energy recovery means is connected to the same potential as the power source.   2. The electromagnetic spill valve control device according to claim 1, wherein the energy recovery means is a ceramic capacitor.   A third switching means (14) provided on the upstream side of the energy recovery means and supplying current to the upstream side of the solenoid of the electromagnetic spill valve based on the energy recovered by the energy recovery means by turning on; The electromagnetic spill valve control device according to claim 1, wherein the electromagnetic spill valve control device is provided.   4. The electromagnetic spill valve control device according to claim 3, wherein the first switching means (11) and the third switching means (14) are turned on in synchronization.