JP2007138893A - Egr valve control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EGR valve control device for correctly confirming that the valve is tightly closed, in the case of controlling the closure of the valve. <P>SOLUTION: In the EGR valve control device, the valve 3 is opened/closed depending on the balance between a force to urge the valve 3 by a return spring 6 in the direction to close the valve, and a force to push the valve 3 by a shaft 14 driven by a motor 8 in the direction to open the valve. The valve control device comprises a detection means 17 for detecting the position of the shaft 14, a memory means 16, and a determination means 16. The memory means 16 stores in advance a learning-position Ps of the shaft 14 in the state in which a prescribed drive duty, which is smaller than the drive duty to allow the valve 3 to start opening against the return spring 6, is input to the motor 8, and at the same time, the valve 3 is at a completely closed position. The determination means 16 determines whether the valve 3 is at the completely closed position or not by making comparison between the learning position Ps and the position Pa of the shaft 14 detected by the detection means 17 in the state in which the specified drive duty control is charged to the motor 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for controlling an EGR valve provided in the middle of an EGR passage connecting an intake passage and an exhaust passage of an engine.

  In order to reduce the amount of NOx (nitrogen oxide) contained in the exhaust gas of the engine, a part of the exhaust gas of the engine is recirculated from the exhaust passage to the intake passage and EGR (exhaust gas recirculation) It is known that EGR that mixes gas with intake air is effective. In other words, when EGR is performed, the oxygen concentration in the intake air decreases and combustion slows down, and generation of NOx can be suppressed due to a decrease in combustion temperature.

  The EGR valve provided in the middle of the EGR passage connecting the intake passage and the exhaust passage of the engine is, for example, a valve that is driven by a force that urges the valve in the closing direction by a return spring and a shaft that is driven by driving means such as a motor. The valve is opened and closed by the balance with the force pushing in the opening direction. Some EGR valves have a structure in which the valve and the shaft are separated.

  In Patent Document 1, a predetermined amount of play is formed between the valve and the shaft when the valve is closed, that is, the shaft is separated from the valve when the valve is closed. A control device for an EGR valve that can guarantee complete closing of the valve even if wear occurs, for example, is disclosed. Also, in this EGR valve control device, the drive duty applied to the motor is gradually increased from the vicinity of the valve origin where the valve starts to open, and the sensor output value (motor that drives the shaft) when it hits the valve origin. The rotor opening position is averaged, and the average value is used as the valve origin, so that the valve opening / closing control can be accurately performed.

JP-A-11-132110

  By the way, in the EGR valve having a structure in which the valve and the shaft are separated from each other, the valve can be fully closed because the shaft can be returned to the valve closing side even when the valve is fixed on the opening side. I can't confirm that. If the valve is open during the closing control of the EGR valve, the exhaust gas purification performance deteriorates. Therefore, it is necessary to confirm that the valve is fully closed during the valve closing control.

  Therefore, an object of the present invention is to provide an EGR valve control device that can accurately confirm that the valve is fully closed during valve closing control.

  In order to achieve the above object, the invention of claim 1 is characterized in that the balance between the force that biases the valve in the closing direction by a return spring and the force that pushes the valve in the opening direction by a shaft driven by a motor. A control device for an EGR valve that opens and closes the valve, the detection means for detecting the position of the shaft, and a predetermined drive duty smaller than the drive duty at which the valve starts to open against the return spring is applied to the motor, Storage means for preliminarily storing the learning position of the shaft in a state where the valve is in a fully closed position; and the position of the shaft and the learning position detected by the detection means in a state where the predetermined driving duty is applied to the motor. And determining means for determining whether or not the valve is in the fully closed position. It comprises a a control device for EGR valve characterized by.

  According to a second aspect of the present invention, when the detected value of the position of the shaft is on the open side of the valve with respect to the learning position, the determination means is fixed on the open side of the fully closed position. 2. When the detected value of the position of the shaft is closer to the valve than the learning position, it is determined that the shaft is fixed closer to the closed position than the fully closed position. It is a control apparatus of the described EGR valve.

  According to the present invention, it is possible to accurately confirm that the valve is fully closed during valve closing control.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic view of an EGR valve control apparatus according to an embodiment of the present invention.

  The EGR valve 1 of this embodiment is provided in the middle of an EGR passage that connects an intake passage and an exhaust passage of an engine.

  As shown in FIG. 1, the EGR valve 1 of the present embodiment includes a housing 2 in which a fluid passage is formed, and a valve 3 supported by the housing 2 so as to be movable up and down. The valve 3 is formed in a shaft shape as a whole, and a valve body 4 is provided at an upper end portion thereof. A flange 5 is provided at the lower end of the valve 3, and a return spring 6 is compressed between the flange 5 and the housing 2 as a biasing means for biasing the valve 3 in the closing direction (X direction). Arranged in a state. When the valve 3 is closed, the valve 3 is seated on the seat portion 7 of the housing 2 by the valve body 4.

  A motor 8 as a driving means for driving the valve 3 is provided at the lower portion of the housing 2. The motor 8 has a casing 9 provided at the lower end of the housing 2. Inside the casing 9, a rotor 11 on which a magnet (permanent magnet) 10 is mounted is rotatably supported. In addition, a coil (electromagnet) 12 is accommodated in the casing 9 so as to surround the rotor 11.

  The shaft 14 is screwed into the rotor 11 at the lower end portion 14a. The shaft 14 is prevented from rotating by the casing 9 at the upper end portion 14b. As a result, the shaft 14 moves in the closing direction (X direction) or the opening direction (Y direction) of the valve 3 in accordance with the rotation amount of the rotor 11. In the present embodiment, the valve 3 and the shaft 14 are separated from each other. When the valve 3 is closed, the tip portion 14b of the shaft 14 is separated from the flange portion 5 of the valve 3. Yes.

  A stopper 15 is provided inside the casing 9 to restrict the movement of the shaft 14 in the closing direction (X direction) of the valve 3 to a predetermined range.

  The motor 8 (coil 12) is connected to the controller 16 and is ON / OFF controlled by a drive signal sent from the controller 16.

  When a driving duty is applied to the motor 8 (coil 12), the rotor 11 of the motor 8 is rotated. As the rotor 11 rotates, the shaft 14 is moved in the opening direction (Y direction) of the valve 3 and is brought into contact with the valve 3. A force that pushes the valve 3 in the opening direction (Y direction) by the shaft 14 (hereinafter referred to as a pushing force of the shaft 14) is a force that biases the valve 3 in the closing direction (X direction) by the return spring 6 (hereinafter, referred to as the pushing force). When the value exceeds the biasing force of the return spring 6), the valve 3 starts to open.

  On the other hand, when the rotor 11 of the motor 8 is rotated in the direction opposite to that when the valve 3 is opened, the shaft 14 is moved in the closing direction (X direction) of the valve 3 as the rotor 11 rotates. Then, the valve 3 is moved in the closing direction (X direction) by the return spring 6.

  Here, the control device for the EGR valve 1 according to the present embodiment performs a fully closed position determination for determining whether or not the valve 3 is in the fully closed position when the valve 3 is closed. This will be described below.

  The control device for the EGR valve 1 according to the present embodiment includes a position sensor 17 as detection means for detecting the position of the shaft 14 in the closing direction (X direction) and the opening direction (Y direction) of the valve 3.

  The controller 16 as a storage means has a predetermined drive duty (hereinafter referred to as a fully closed position learning drive duty) slightly smaller than the drive duty at which the valve 3 starts to open against the return spring 6 in the motor 8 (coil 12). 8 (coil 12) is brought into contact with the flange portion 5 of the valve 3 with the tip 14b of the shaft 14 over a predetermined time, and the position Ps of the shaft 14 in the state where the valve 3 is in the fully closed position (hereinafter referred to as this). Is stored in advance (refer to FIG. 2). In other words, the fully closed position learning drive duty is such that a pressing force that does not cause the valve 3 to open is generated in the shaft 14, and is preferably set so that the pressing force of the shaft 14 and the biasing force of the return spring 6 are balanced. Is done.

  The controller 16 applies a drive duty substantially equal to the fully closed position learning drive duty to the motor 8 (coil 12) for a predetermined time (the valve 3 and the shaft 14) when the engine is in an operating state and the valve 3 is in an uncontrolled state. Is set longer than the time required for the shaft 14 to come into contact with the valve 3), and the position sensor 17 detects the position Pa of the shaft 14 in that state.

  For example, in the present embodiment, the controller 16 determines that the engine is in an operating state when a key (ignition key) is in an ON state. Further, in the present embodiment, the controller 16 determines that the valve 3 is in an uncontrolled state when the target value of the opening degree of the valve 3 is instructed to fully close for a predetermined time (for example, about five seconds). To do.

  Then, when there is almost no difference (shift) between the position Pa of the shaft 14 detected by the position sensor 17 and the learning position Ps, the controller 16 as the determination means has the valve 3 at that time in an appropriate position. 3 is determined to be in the fully closed position and normal.

  On the other hand, when the shaft position Pa detected by the position sensor 17 and the learning position Ps are misaligned, it can be estimated that the valve 3 or the shaft 14 deviates from an appropriate position.

  Specifically, as shown in FIG. 3, the controller 16 determines that the position Pa of the shaft 14 is larger than the learning position Ps, that is, the shaft position Pa is closer to the opening direction side (Y direction side) of the valve 3 than the learning position Ps. ), It is determined that the valve 3 is fixed on the open side of the fully closed position. That is, in this case, it can be estimated that the valve 3 is fixed on the open side with respect to the fully closed position, and the shaft 14 has moved beyond the learning position Ps to the opening direction side (Y direction side) of the valve 3.

  On the other hand, as shown in FIG. 4, when the position Pa of the shaft 14 is smaller than the learning position Ps, the controller 16 indicates that the position Pa of the shaft 14 is closer to the closing direction of the valve 3 (X direction) than the learning position Ps. In the case of the side), it is determined that the shaft 14 is fixed on the closed side with respect to the fully closed position of the valve 3. That is, in this case, it can be estimated that the shaft 14 is fixed on the closed side with respect to the fully closed position of the valve 3 and the shaft 14 cannot move to the opening direction side (Y direction side) of the valve 3.

  A specific determination method will be described with reference to the flowchart of FIG. This flowchart is executed by the controller 16.

  First, in step S1, the controller 16 determines whether the key (ignition key) is in an ON state, that is, whether the engine is in an operating state.

  If the engine is in an operating state, the process proceeds to step S2. In step S2, the controller 16 determines whether or not the state in which the target value of the opening degree of the valve 3 is instructed to be fully closed continues for a predetermined time (for example, about 5 seconds). That is, it is determined whether the valve 3 is in an uncontrolled state.

  If the valve 3 is in an uncontrolled state, the process proceeds to step S3. In step S3, the controller 16 applies a drive duty equal to the fully closed position learning drive duty to the motor 8 (coil 12) for a predetermined time (the valve 3 and the shaft 14 are normal). It is set longer than the time required for the shaft 14 to come into contact with the valve 3).

  Thereafter, in step S4, the controller 16 detects the position Pa of the shaft 14 by the position sensor 17 in a state where a driving duty equal to the fully closed position learning driving duty is applied to the motor 8 (coil 12). It is determined whether the position Pa and the learning position Ps are different.

  If the detected position Pa of the shaft 14 is different from the learning position Ps, the process proceeds to step S5, and in step S5, the controller 16 determines whether the detected position Pa of the shaft 14 is larger than the learning position Ps.

  If the detected position Pa of the shaft 14 is larger than the learning position Ps, the controller 16 determines that the valve 3 is fixed on the open side of the fully closed position (step S6). If the detected position Pa of the shaft 14 is smaller than the learning position Ps, the controller 16 determines that the shaft 14 is fixed on the closed side of the fully closed position of the valve 3 (step S9).

  On the other hand, if the key (ignition key) is not in the ON state in step S1, and if the state in which the target value of the opening degree of the valve 3 is instructed to be fully closed in step S2 does not continue for a predetermined time, the controller 16 does not perform the fully closed position determination (step S7).

  When the position Pa of the shaft 14 detected in step S4 and the learning position Ps are substantially equal, the controller 16 determines that the valve 3 is in the fully closed position and is normal (step S8).

  In short, according to the present embodiment, it is possible to accurately confirm that the valve 3 is fully closed during the valve closing control of the valve 3.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various other embodiments can be adopted.

It is the schematic of the control apparatus of the EGR valve which concerns on one Embodiment of this invention. It is sectional drawing of the EGR valve | bulb which shows the state which has a shaft in a learning position. It is sectional drawing of the EGR valve | bulb which shows the state which the valve | bulb has adhered to the open side rather than the fully closed position. It is sectional drawing of the EGR valve | bulb which shows the state which the shaft has adhered on the closed side rather than the fully closed position of a valve | bulb. It is a process flowchart by a controller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 EGR valve 3 Valve 6 Return spring 8 Motor 14 Shaft 16 Controller (memory | storage means, determination means)
17 Position sensor (detection means)
Pa Shaft position Ps Learning position

Claims (2)

A control device for an EGR valve that opens and closes the valve by a balance between a force for urging the valve in the closing direction by a return spring and a force for pushing the valve in the opening direction by a shaft driven by a motor,
A detecting means for detecting the position of the shaft, a predetermined driving duty smaller than a driving duty at which the valve starts to open against the return spring is applied to the motor, and the valve is in a fully closed position. The valve is in a fully closed position by comparing the learning position with storage means for preliminarily storing the learning position of the shaft and the position of the shaft detected by the detection means in a state where the predetermined driving duty is applied to the motor. A control device for an EGR valve, comprising: determination means for determining whether or not   The determination means determines that the valve is fixed on the open side of the fully closed position when the detected value of the position of the shaft is on the open side of the valve with respect to the learning position, and the shaft 2. The EGR valve control device according to claim 1, wherein when the detected value of the position is closer to the valve closing side than the learning position, it is determined that the shaft is fixed closer to the closing side than the fully closed position. .

Images