Pressure reducing valve drive device

Abstract

To provide a device that can definitely depressurize the pressure in a common rail even when an anomaly occurs in a drive IC etc. in a configuration in which a normally-closed type pressure reduction valve is used.SOLUTION: In a pressure reduction valve drive device 1, a drive IC 3 controls drive of an energizing unit 4 that energizes a normally-closed type pressure reduction valve 8 for depressurizing the pressure in a common rail. A microcomputer 2 controls the drive IC 3. A monitor IC 5 monitors the drive IC 3 and the microcomputer 2. A forced drive unit 6 outputs a signal for forcibly driving the pressure reduction valve 8 to the energizing unit 4 when an anomaly occurs in one or more of the microcomputer 2, the drive IC 3, and the monitor IC 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a device for reducing the pressure in a common rail by using a pressure reducing valve. Drive

Background Art

[0002] Patent Document 1 discloses a technique for controlling a pressure reducing valve in order to reduce the pressure in a common rail in a fuel injection system of a common rail in a diesel engine. This technique controls the opening and closing of the pressure reducing valve by controlling the current and time for energizing the pressure reducing valve, so as to control the pressure in the common rail to a target value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique of Patent Document 1, it is assumed that a normally closed type is adopted for the pressure reducing valve. In this case, the valve opens when the pressure reducing valve is energized, and the pressure in the common rail can be reduced. Therefore, if an abnormality occurs in the drive IC that controls the current supplied to the pressure reducing valve, the microcomputer or monitoring IC that controls the operation of the drive IC, the pressure reducing valve cannot be energized to open, and there is a risk that the pressure in the common rail cannot be reduced.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a pressure reducing valve driving device that can reliably reduce the pressure in the common rail even when an abnormality occurs in a drive IC or the like in a configuration using a normally closed type pressure reducing valve.

Means for Solving the Problems

[0006] ​ According to the pressure reducing valve drive device of claim 1, the drive IC controls the drive of the energizing unit that energizes a normally closed type pressure reducing valve that reduces the pressure in the common rail. A microcomputer controls the drive IC, and a monitoring IC monitors the drive IC and the microcomputer. The forced drive unit is It is configured outside the driver IC, If a malfunction occurs in one or more of the drive IC, microcontroller, or monitoring IC, a signal is output to the power supply unit to forcibly drive the pressure reducing valve. With this configuration, even if a malfunction occurs in any of the drive IC, microcontroller, or monitoring IC, the forced drive unit can forcibly drive the pressure reducing valve to open it, thereby reducing the pressure in the common rail.

[0007] According to the pressure reducing valve drive device of claim 2, the pressure determination unit determines that the pressure in the common rail exceeds a threshold, and the current determination unit determines that the current supplied to the pressure reducing valve falls below a threshold. The energizing unit includes switches located on the high-potential side and the low-potential side of the pressure reducing valve, respectively. When the abnormality occurs, the forced drive unit turns on both switches, provided that the pressure exceeds the threshold and the current falls below the threshold. Then, from the on state, the other switch is turned off, provided that the current exceeds the threshold. This allows the current supplied to the pressure reducing valve to be controlled to a predetermined value. [Brief explanation of the drawing]

[0008] [Figure 1] This is one embodiment, and the diagram shows the configuration of the pressure reducing valve drive device. [Figure 2] A flowchart showing the routines the microcontroller uses to diagnose the driver IC and the monitoring IC 5, respectively. [Figure 3] Timing chart showing the operation of each part [Figure 4] This is a reference example and shows the configuration of a pressure reducing valve drive device. [Modes for carrying out the invention]

[0009] ( one (Embodiment) below, one An embodiment will now be described. As shown in Figure 1, the pressure reducing valve drive device 1 comprises a microcontroller 2, a drive IC 3, a power supply unit 4, a monitoring IC 5, and a forced drive unit 6. The power supply unit 4 comprises a P-channel MOSFET 4H as a high-side driver and an N-channel MOSFET 4L as a low-side driver. A series circuit of FET 4H, pressure reducing valve 8, FET 4L, and current detection circuit 9 is connected between the power supply VB and ground. FET 4H and 4L are examples of switches.

[0010] The pressure reducing valve 8 is a normally closed type and, although not shown in the diagram, is used to reduce the pressure in the common rail of a diesel engine mounted on a vehicle. The current detection circuit 9 detects the load current supplied to the pressure reducing valve 8 when FETs 4H and 4L are turned on and inputs the detected value to the forced drive unit 6. The microcontroller 2 controls the drive IC 3 to drive the energizing unit 4. The drive IC 3 outputs a drive signal to the gates of FETs 4H and 4L. The microcontroller 2 also monitors the operation of the drive IC 3, for example, using a watchdog timer. The monitoring IC 5 monitors the operation of the microcontroller 2 and the drive IC 3. The microcontroller 2 also monitors the operation of the monitoring IC 5.

[0011] The forced drive unit 6 includes a pressure determination unit 10, a current value determination unit 11, and AND gates 12 and 13. The input terminal of the pressure determination unit 10 is connected to the terminal of a pressure sensor located on the common rail. The terminal of the pressure sensor is also connected to the input port of the microcontroller 2. When the pressure in the common rail exceeds a threshold, the microcontroller 2 turns on FETs 4H and 4L via the drive IC 3. When the pressure determination unit 10 of the forced drive unit 6 exceeds the threshold, it outputs a high-level signal to one of the input terminals of the AND gate 12.

[0012] When monitoring IC 5 determines that an abnormality has occurred in microcontroller 2 or driver IC 3, it outputs a high-level abnormality signal to the other input terminal of AND gate 12. When microcontroller 2 determines that an abnormality has occurred in driver IC 3 or monitoring IC 5, it also outputs a high-level abnormality signal to the above input terminal. The output terminal of AND gate 12 is connected to the gate of FET 4L and is also connected to one of the input terminals of AND gate 13.

[0013] The current value determination unit 11 outputs a high-level signal to the other input terminal of the AND gate 13 when the current value input from the current detection circuit 9 exceeds a threshold. The output terminal of the AND gate 13 is connected to the gate of the FET 4H. The forced drive unit 6 is composed of discrete components.

[0014] Next, the operation of this embodiment will be described. As shown in Figure 2, the microcontroller 2 executes routines 1 and 2, respectively, to diagnose the drive IC 3 and the monitoring IC 5. If it is determined in step S1 that an abnormality has occurred in the drive IC 3, or if it is determined in step S3 that an abnormality has occurred in the monitoring IC 5, it outputs an abnormality signal to the forced drive unit 6 (S2, S4).

[0015] As shown in Figure 3, in the initial state, the voltage at point (A), which is the gate of FET4H, is high, and the voltage at point (B), which is the gate of FET4L, is low. Therefore, the pressure reducing valve 8 is de-energized and closed. Since the pressure sensor signal exceeds the threshold, if the microcontroller 2 and the drive IC 3 are operating normally, the microcontroller 2 controls the energizing unit 4 via the drive IC 3, energizing the pressure reducing valve 8 and opening it.

[0016] While the non-energized state of the pressure reducing valve 8 continues, if the monitoring IC5 detects that an abnormality has occurred in at least one of the microcomputer 2 or the driving IC3, it outputs an abnormality signal to the forced driving unit 6. Then, the output signal of the AND gate 12 becomes high level. At this time, since the current value detected by the current detection circuit 9 is below the threshold value, the output signal of the AND gate 13 becomes low level. As a result, both FET4H and 4L turn on, the pressure reducing valve 8 is energized, and the load current value increases.

[0017] When the load current rises to a certain extent, the pressure reducing valve 8 opens and the pressure in the common rail starts to decrease. When the load current value exceeds the threshold value, the output signal of the AND gate 13 becomes high level and FET4H turns off. Then, the load current value decreases, but when it falls below the threshold value, FET4H turns on again. By repeating this operation, the load current value is controlled to maintain a predetermined value.

[0018] And when the IC5 maintains the output of the abnormality signal and the pressure in the common rail falls below the threshold value, the output signal of the AND gate 12 becomes low level and FET4L turns off. Therefore, after reducing the pressure in the common rail to below the threshold value, the pressure reducing valve 8 is energized ru the current decreases, the pressure reducing valve closes, and the inside of the common rail can maintain a predetermined low pressure.

[0019] As described above, according to this embodiment, in the pressure reducing valve driving device 1, the driving IC3 controls the driving of the energizing unit 4 that energizes the normally closed type pressure reducing valve 8 that reduces the pressure in the common rail. The microcomputer 2 controls the driving IC3, and the monitoring IC5 monitors the driving IC3 and the microcomputer 2. When an abnormality occurs in any one or more of the microcomputer 2, the driving IC3, and the monitoring IC5, the forced driving unit 6 outputs a signal for forcibly driving the pressure reducing valve 8 to the energizing unit 4. With such a configuration, even when an abnormality occurs in any of the microcomputer 2, the driving IC3, and the monitoring IC5, it is possible to forcibly drive the pressure reducing valve 8 by the forced driving unit 6 to open it and reduce the pressure in the common rail.

[0020] Specifically, the pressure determination unit 10 determines that the pressure in the common rail has exceeded the threshold value, and the current value determination unit 11 determines that the load current supplied to the pressure reducing valve 8 has fallen below the threshold value. The energization unit 4 includes FETs 4H and 4L disposed on the high potential side and the low potential side of the pressure reducing valve 8, respectively. When the abnormality occurs, the forced drive unit 6 turns on both FETs 4H and 4L on the condition that the pressure has exceeded the threshold value. Then, during the occurrence of the abnormality, FET 4H is turned off on the condition that the load current has fallen below the threshold value. Thereby, the load current can be controlled to a predetermined value.

[0021] ( Reference example ) Hereinafter, one the same parts as those in the embodiment are denoted by the same reference numerals and the description thereof is omitted, and different parts will be described. In the pressure reducing valve drive device 21 shown in FIG. 4, Reference example the difference is that the forced drive unit 6 is configured inside the drive IC 22.

[0022] (Other Embodiments) When forcibly driving the pressure reducing valve 8, FET 4L may be intermittently turned on while FET 4H is kept on. The switch is not limited to a MOSFET, and may be an IGBT, a bipolar transistor, or the like. The means for detecting an abnormality is not limited to a watchdog timer. Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further other combinations and forms including only one element, more than one element, or less than one element thereof are also within the scope and spirit of the present disclosure.

Description of Reference Numerals

[0023] In the drawings, 1 denotes a pressure reducing valve drive device, 2 denotes a microcomputer, 3 denotes a drive IC, 4 denotes an energization unit, 4H denotes a P-channel MOSFET, 4L denotes an N-channel MOSFET, 5 denotes a monitoring IC, 6 denotes a forced drive unit, 8 denotes a pressure reducing valve, 10 denotes a pressure determination unit, and 11 denotes a current value determination unit.

Claims

1. A normally closed type pressure reducing valve (8) that reduces the pressure inside the common rail is energized by an energizing unit (4), A drive IC (3) controls the operation of this energized section, This drive IC is controlled by a microcomputer (2), A monitoring IC (5) that monitors the aforementioned drive IC and the aforementioned microcomputer, A pressure reducing valve drive device comprising a forced drive unit (6) configured outside the drive IC, which outputs a signal to the energizing unit to forcibly drive the pressure reducing valve when an abnormality occurs in one or more of the microcomputer and the monitoring IC.

2. A pressure determination unit (10) that determines whether the pressure in the common rail exceeds a threshold, The device includes a current determination unit (11) that determines whether the current supplied to the pressure reducing valve has fallen below a threshold, The energizing section includes switches (4H, 4L) positioned on the high-potential side and the low-potential side of the pressure reducing valve, respectively. When the abnormality occurs, the forced drive unit turns on both switches, provided that the pressure exceeds a threshold and the current falls below a threshold. The pressure reducing valve drive device according to claim 1, wherein the other of the two switches is turned off when the current exceeds a threshold value from the ON state.

3. The pressure reducing valve drive device according to claim 1 or 2, wherein the monitoring IC outputs an abnormality signal to the forced drive unit when it detects an abnormality in the microcomputer.

4. The pressure reducing valve drive device according to claim 1 or 2, wherein the monitoring IC detects an abnormality in the drive IC and outputs an abnormality signal to the forced drive unit.

5. The pressure reducing valve drive device according to claim 1 or 2, wherein the microcomputer detects an abnormality in the monitoring IC and outputs an abnormality signal to the forced drive unit.

6. The pressure reducing valve drive device according to claim 1 or 2, wherein the microcomputer detects an abnormality and outputs an abnormality signal to the forced drive unit.

7. The pressure reducing valve drive device according to claim 1 or 2, wherein the microcomputer detects an abnormality in the drive IC and outputs an abnormality signal to the forced drive unit.

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