JP2007085214A - Metering mechanism of fluid feeding device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metering mechanism of a fluid feeding device for an engine easily controlling the position of a metering cylinder and accurately controlling the feed amount of fluid into cylinders. <P>SOLUTION: The metering cylinder 11 is disposed between a pressure source unit 3 and an injection valve 4, and a piston 24 is disposed therein. The position of the piston is detected by a detector 27. A metering chamber 26 and a pressure chamber 25 are demarcated by a piston 24, and the pressure chamber 25 is connected to the pressure source unit 3. The metering chamber 26 is connected to the pressure source unit 3 through a solenoid valve 12, and then connected to the injection valve 4. The moving speed of the piston is set lower during accumulation than that during discharge. A control device 4 controls the position of the piston during accumulation by controlling openinng/closing operations of the solenoid valve 12 by proportional integral control on the basis of the detected result of the position of the piston and the target value of the feed amount of the fluid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates between a pressure source unit that supplies fluid for injection and an injection valve that injects fluid supplied from the pressure source unit via an injection port formed in an engine cylinder and supplies the fluid into the cylinder. The present invention relates to a metering mechanism of an engine fluid supply device that controls the amount of fluid supplied into a cylinder.

  Between the pressure source unit that supplies the fluid for injection and the injection valve that injects the fluid supplied from the pressure source unit via the injection port formed in the cylinder of the engine and supplies the fluid into the cylinder. As the metering mechanism of the engine fluid supply device that controls the fluid supply amount of the engine, one that uses a metering cylinder is considered. However, even if a metering cylinder is used, the distance between each cylinder and the pressure source unit differs depending on each cylinder, and also due to the influence of the pressure fluctuation of the fluid pressure source unit, etc. Furthermore, there is a problem that the fluid supply amount varies depending on the timing of each injection in each cylinder.

  In order to suppress such a variation in the amount of fluid supply, one applied to a diesel engine that performs fuel injection using an electronically controlled solenoid valve is known (see Patent Document 1). The diesel engine described in Patent Literature 1 includes a hydraulic drive unit having a common hydraulic pressure source and a pressure increasing unit, and drives the pressure increasing piston of the pressure increasing unit by the common hydraulic source. Then, a signal related to the operation of the boosting piston lift for each cylinder is sampled at a constant period to calculate the sum of sampling values during the solenoid valve driving period, and the sum of the sampling values of all the cylinders is obtained. Proportional integral control with the average value as the set value and the total sampling value of each cylinder as the control amount is performed to adjust the drive time of the solenoid valve, and to suppress the variation in the fuel injection amount among the cylinders. .

JP 2004-263617 A (page 4-5, Fig. 1-3)

  However, in the diesel engine described in Patent Document 1, the driving time of the solenoid valve when supplying fluid is adjusted by driving the pressure-increasing piston of the pressure-increasing part with a common hydraulic power source, and at high speed. High-speed arithmetic processing for controlling the fluid supply amount in accordance with the supply rate of the fluid to be ejected is required. For this reason, there is a restriction that it is necessary to use a control unit capable of such high-speed processing, and control adjustment itself may be difficult.

  The present invention provides an engine fluid supply device that controls the amount of fluid supplied into a cylinder between a pressure source unit and an injection valve that injects fluid supplied from the pressure source unit and supplies the fluid into the cylinder. An object of the mechanism is to solve the above-described problems. That is, according to the present invention, the metering mechanism of the engine fluid supply apparatus that can easily control the position in the metering cylinder and can more accurately control the amount of fluid supplied into the cylinder, in view of the above situation. The purpose is to provide.

Means and effects for solving the problems

  The metering mechanism of the engine fluid supply apparatus according to the present invention injects the fluid supplied from the pressure source unit via the pressure source unit that supplies the fluid for injection and the injection port formed in the cylinder of the engine. The present invention relates to a metering mechanism of an engine fluid supply device that controls a fluid supply amount into the cylinder between the injection valve supplied into the cylinder. In order to achieve the above-described object, a measuring cylinder disposed between the pressure source unit and the injection valve and having a piston disposed therein, and provided in the measuring cylinder and partitioned by the piston. A pressure chamber and a metering chamber, the pressure chamber connected to the pressure source unit, the metering chamber connected to the pressure source unit via an electromagnetic valve and connected to the injection valve, A detector for detecting a position of the piston, a control unit to which a detection signal based on a detection result of the position of the piston by the detector and a command value corresponding to a target value of the fluid supply amount are input; and the piston And a delay means for setting the moving speed of the storage chamber to be slower than the discharge time for supplying the fluid from the measurement chamber to the injection valve. , It said by controlling the opening and closing operation of the detection signal and the solenoid valve by a proportional integral control based on the command value, and controls the position of the piston during the storage at the storage.

  According to this configuration, the moving speed of the piston during accumulation is set to be slowed by the delay means, and the opening / closing operation of the solenoid valve is controlled by proportional integral control during accumulation by the control unit, so that the position of the piston during accumulation is determined. Be controlled. For this reason, the supply amount accumulated in the measuring chamber is accurately controlled. In addition, the control unit performs proportional-integral control based on the detection signal of the piston position and the command value to control the piston position, so even when the command value changes, the supply amount accumulated in the measuring chamber is controlled by the command. It is possible to quickly follow the change in value. Therefore, the position control in the measuring cylinder can be easily performed, and the measuring mechanism of the engine fluid supply apparatus capable of more accurate control of the fluid supply amount into the cylinder can be provided.

  In the metering mechanism of the engine fluid supply device according to the present invention, the control unit calculates a difference calculated based on the command value and the detection signal, and the value of the difference is close to a zero value. A dead zone setting device that converts the difference value to a value closer to zero at times, and controlling the opening / closing operation of the solenoid valve by proportional-integral control based on the output through the dead zone setting device desirable.

  According to this configuration, when the actually supplied supply amount approaches the target value of the fluid supply amount, the difference value can be converted to a value close to the zero value and controlled based on the output. It is possible to suppress the occurrence of hunting due to the occurrence of a chute or the like and the control system becoming unstable.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. The metering mechanism of the engine fluid supply apparatus according to the embodiment of the present invention injects the fluid supplied from the pressure source unit via the pressure source unit that supplies the fluid for injection and the injection port formed in the cylinder of the engine. Thus, the present invention can be widely applied to the case where the fluid supply amount into the cylinder is controlled between the injection valve and the injection valve supplied into the cylinder. In the present embodiment, a case where it is used as a metering mechanism of an engine fluid supply device for injecting water into a cylinder of a diesel engine will be described as an example from the viewpoint of reducing emission of nitrogen oxides (NOx).

  FIG. 1 is a circuit configuration diagram of an engine fluid supply apparatus 2 in which a metering mechanism 1 (hereinafter simply referred to as “metering mechanism 1”) of an engine fluid supply apparatus according to an embodiment of the present invention is used. 2 is a schematic diagram of an engine fluid supply apparatus 2 shown to explain the metering mechanism 1. As shown in FIGS. 1 and 2, the engine fluid supply device 2 includes a metering mechanism 1, a pressure source unit 3, and an injection valve 4.

  The pressure source unit 3 is a water pressure source that supplies water for injection (fluid) from the injection valve 4, and includes a pump 5 and an accumulator 6. The pump 5 is connected to a tank (not shown), pressurizes the water sucked from this tank, and discharges it to the accumulator 6. The water discharged from the pump 5 is sent to the accumulator 6 where the water is stored in a high pressure state close to the discharge pressure of the pump 5. Then, the water stored in the accumulator 6 is supplied to the metering mechanism 1 and is injected from the injection valve 4 through the metering mechanism 1.

  The injection valve 4 is attached to a diesel engine (engine) (not shown), and water supplied from the pressure source unit 3 is supplied through an injection port formed in a cylinder (cylinder) (not shown) in the diesel engine. It can inject and supply in a cylinder. In addition, reduction of discharge of nitrogen oxides (NOx) is achieved by injecting water from the injection valve 4 into the cylinder of the diesel engine. Further, water is directly injected into the cylinder from the injection valve 4.

  As shown in FIGS. 1 and 2, the metering mechanism 1 includes a metering cylinder 11, a solenoid valve 12, a main valve 13, and a control device (control unit) 14, and a water supply amount (fluid supply) into the cylinder. Control). The metering mechanism 1 is provided with a passage 15 as a system through which water supplied from the pressure source unit 3 flows. In the present embodiment, the electromagnetic valve 12 and the main valve 13 are described as being included in the metering mechanism 1, but these may not necessarily be components of the metering mechanism 1, and the engine fluid supply device 2 It may be provided as included.

  As the passage 15 in the measuring mechanism 1, passages 15a to 15e are provided. The passages 15 a and 15 b are provided so as to connect the pressure source unit 3 to the measuring cylinder 11 and the solenoid valve 12. The passages 15c and 15d are provided so as to connect the measuring cylinder 11, the solenoid valve 12, and the main valve 13. The passage 15 e connects the main valve 13 and the injection valve 4. Thereby, the passage of water between the pressure source unit 3 and the injection valve 4 via the measuring cylinder 11 and the main valve 13 is allowed.

  The main valve 13 includes a main body 16, a valve seat 17, a valve body 18, a spring 19, and an electromagnetic solenoid 20. The main body 20 is formed with a pressure source unit side port 21 to which water from the pressure source unit 3 is supplied and an injection valve side port 22 for supplying water to the injection valve 4. That is, the pressure source unit side port 21 is connected to the passage 15d, and the injection valve side port 22 is connected to the passage 15e. Further, the valve seat 17 is formed between the pressure source unit side port 21 and the injection valve side port 22, and the valve body 18 is formed so as to be seated on the valve seat 17 between the passage 15d and the passage 15e. It is arranged so that it can be opened and closed. That is, the passage 15 is blocked (closed) when the valve body 18 is seated on the valve seat 17, and the passage 15 is opened (communicated) when the valve body 18 is separated from the valve seat 17. )

  Further, the spring 19 in the main valve 13 is provided as a coil spring disposed in a spring chamber 23 that is partitioned and formed in the main body 16 and biases the valve body 18 in the seating direction. . The valve body 18 is seated on the valve seat 17 by the urging force of the spring 19 so that the passage 15 is blocked.

  The electromagnetic solenoid 20 is disposed in a position facing the valve body 18 in the main body 16 so that the valve body 18 can be attracted in the separating direction. In a state where the electromagnetic solenoid 20 is demagnetized, the passage 15 is kept closed while the valve body 18 is seated on the valve seat 17 by the urging force of the spring 19 (that is, a normal state that is not excited). In a normal state, it is in a normally closed state where the passage 15 is closed). On the other hand, when the electromagnetic solenoid 20 is energized and excited, the valve body 18 is attracted and separated from the valve seat 17 and the passage 15 is opened.

  The metering cylinder 11 is disposed between the passage 15a and the passage 15d on the upstream side of the main valve 13 between the pressure source unit 3 and the injection valve 4. The measuring cylinder 11 is provided with a piston 24, a pressure chamber 25, a measuring chamber 26, a position sensor (detector) 27, and a spring 28. The piston 24 is disposed inside the measuring cylinder 11 so as to be able to reciprocate. The pressure chamber 25 and the measuring chamber 26 are defined by a piston 24 in the measuring cylinder 11.

  The pressure chamber 25 of the measuring cylinder 11 is connected to the pressure source unit 3 through a passage 15a. On the other hand, the measuring chamber 26 is connected to the passage 15d, is connected to the pressure source unit 3 through the electromagnetic valve 12, and is connected to the pressure source unit side port 21 of the main valve 13. Further, a spring 28 is disposed in the measuring chamber 26 so as to bias the piston 24 toward the pressure chamber 25. Note that the end wall 26 a of the measuring chamber 26 also functions as a stopper that restricts the movement of the piston 24 when water is discharged (supplied) from the measuring chamber 26. That is, when water is discharged from the measuring chamber 26, the end surface 24a of the piston 24 located in the measuring chamber 26 contacts the end wall 26a, so that the stroke of the piston 24 during water discharge is regulated. It has come to be. The state in which the end surface 24a of the piston 24 is in contact with the end wall 26a is a reference position for starting accumulation when water for supply to the cylinder is accumulated in the measuring chamber 26.

  The position sensor 27 detects the position of the piston 24 in the measuring cylinder 11. As shown in FIG. 2, the position sensor 27 can issue a detection signal based on the detection result of the position of the piston 24 to the control device 14. In addition, the detection of the piston position by the position sensor 27 is detected using, for example, a state in which the end surface 24a of the piston 24 is in contact with the end wall 26a as a reference position. Thereby, the movement amount of the piston 24 from the accumulation start position when accumulating the water for supply to the cylinder in the measuring chamber 26 can be detected.

Further, the solenoid valve 12 is disposed between the passage 15b and the passage 15c that can supply water from the pressure source unit 3 to the measuring chamber 26 of the measuring cylinder 11, and can open and close between the passages 15b and 15c. It has become. The electromagnetic valve 12 includes a main body 12a, a valve seat 12b formed in the main body 12a, a valve body 12c, a coil portion 12d, and a spring 12e. The valve seat 12b is formed between the passage 15b and the passage 15c, and the valve body 12c is disposed so as to be seated on the valve seat 12b. In addition, the valve body 12c is a spring 12
While being energized by e in the seating direction and energized to the coil portion 12d (by being excited), it is arranged to be separated from the valve seat 12b. Thereby, in the solenoid valve 12, in the demagnetized state, the valve body 12c is biased by the spring 12e and moves in a direction to close between the passage 15b and the passage 15c, and in the excited state, The valve body 12c moves in the direction to open the passage against the urging force of the spring 12e. That is, the solenoid valve 12 is in a normally closed state that is a position where the passages 15b and 15c are closed in a normal state where the solenoid valve 12 is not excited.

  The control device 14 shown in FIG. 2 includes a CPU (Central Processing Unit), a memory (ROM (Read Only Memory), RAM (Random Access Memory)), a current control circuit, and the like (not shown). And this control apparatus 14 is connected so that it can energize and energize to the coil part 12d of the solenoid valve 12, and the solenoid solenoid 20 of the main valve 13, respectively, The operation | movement of each of these valves (12, 13) is carried out. It can be controlled. And the control apparatus 14 is connected with the position sensor 27 of the measuring cylinder 11, and the detection signal regarding the piston position detected by the position sensor 27 is input. Further, a command value corresponding to a target value of the water supply amount supplied from the injection valve 4 into the cylinder is input to the control device 14. Note that the control device 14 controls each valve (including the above-mentioned command value) from an engine control unit (not shown) that controls the operation of a diesel engine (not shown) provided with the injection valve 4. 12, 13) is controlled, and the operation of each valve (12, 13) is controlled at a predetermined timing synchronized with the cycle of the diesel engine controlled by the engine control unit. .

  In the metering mechanism 1, the moving speed of the piston 24 of the metering cylinder 11 is slower during the accumulation in which water is accumulated in the metering chamber 26 than during the discharge of supplying water from the metering chamber 26 to the injection valve 4. Delay means for setting is provided. This delay means is constituted by, for example, a water inflow path to the spring 28 of the measuring cylinder 11 or the measuring chamber 26. That is, the setting by the delay means is performed by appropriately selecting the spring force of the spring 28, which is one of the factors affecting the moving speed of the piston 24 when water is supplied to the measuring chamber 26, the electromagnetic valve 12, the passage 15a, It is determined by adjusting the flow resistance of 15b and 15c.

  Next, the operation of the weighing mechanism 1 having the above-described configuration will be described. FIG. 3 is a control conceptual diagram illustrating processing in the control device 14 of the weighing mechanism 1. The control device 14 controls the opening / closing operation of the solenoid valve 12 by proportional-integral control based on the detection signal from the position sensor 27 and the aforementioned command value when water is accumulated in the measuring chamber 26 of the measuring cylinder 11. The position of the piston 24 during the accumulation is controlled. That is, the processing shown in FIG. 3 is performed at each timing of accumulating water in the measuring chamber 26, and at each timing, the opening / closing operation of the electromagnetic valve 12 is controlled at the timing determined in the processing of FIG. It will be.

  First, a detection signal from the position sensor 27 and a command value that is a target value of the water supply amount are input to the control device 14. As the detection signal of the position sensor 27, the position of the piston 24 in a state after the accumulation of water in the measuring chamber 26 and before the water is supplied to the injection valve 4 is input. When the detection signal related to the piston position is input to the control device 14, the control device 14 stores the previous water accumulation timing in the weighing chamber 26 at the previous water accumulation timing (converted from the value of the piston position). The actual value obtained by calculating the water supply amount (injection amount) to be supplied at the timing of the next water injection) is obtained.

  Then, the control device 14 calculates a difference ΔVi between the command value and the water supply amount (that is, the difference ΔVi is calculated based on the detection signal of the position sensor 27 and the command value). Further, the control device 14 is configured to include a dead zone setting device that converts the value of the difference ΔVi so as to be closer to the zero value when the value of the difference ΔVi is close to the zero value. The control conceptual diagram shown in FIG. 3 shows a case where the difference ΔVi is converted to the newly calculated difference ΔVo through the dead zone setting device, and the difference ΔVi before conversion is set to a predetermined threshold value appropriately set. The case where it is converted to a value close to zero by the case of ΔVα or less is illustrated.

  Subsequently, the control device 14 performs an operation for proportional-integral control based on the difference ΔVo that is an output converted through the dead zone setting device. That is, a proportional control calculation and an integral control calculation for calculating an operation change amount according to the difference ΔVo are performed under a predetermined proportional coefficient and an integral coefficient gain setting appropriately set. The next operation amount is calculated so as to be changed by the change amount. Note that the previous operation amount is the operation amount previously calculated by the previous control device 14. On the other hand, the next operation amount corrected in consideration of the operation change amount with respect to the previous operation amount corresponds to the control output of the solenoid valve 12 at the next water accumulation timing.

  When the next operation amount is calculated, the limiter determines that the value is within a range between a predetermined upper limit value (UL) and a lower limit value (LL). If it is not within the range of the upper and lower limits, the next manipulated variable is changed to be the same value as the upper limit or lower limit value that has exceeded the upper and lower limits, so that it is within the upper and lower limits. For example, the value of the next operation amount is not changed. Then, based on the next operation amount that is an output that has passed through the limiter, the valve opening time of the electromagnetic valve 12 necessary for accumulating water for the next operation amount in the measuring chamber 26 is set. Through the processing shown in FIG. 3, the opening / closing operation of the electromagnetic valve 12 is controlled according to the output from the control device 14, and the position of the piston 24 during accumulation is controlled.

  Here, regarding the operation of the metering mechanism 1, the cycle from when the water accumulated in the metering chamber 26 of the metering cylinder 11 is supplied into the cylinder via the injection valve 4 until the water is accumulated again in the metering chamber 26. explain.

  First, in a state where both the solenoid valve 12 and the main valve 13 are closed and water is accumulated in the metering chamber 26 of the metering cylinder 11, when the predetermined timing for injecting water from the injector 4 is reached, the control device 14. Thus, the electromagnetic solenoid 20 of the main valve 13 is controlled to be excited. As a result, the main valve 13 is opened (see FIGS. 1 and 2). Since water of a predetermined pressure is supplied from the pressure source unit 3 to the pressure chamber 25 of the measuring cylinder 11, the piston 24 biased by the pressure of the water moves. By the movement of the piston 24, the water accumulated in the measuring chamber 26 is supplied from the injection valve 4 into the cylinder through the main valve 13.

  After the end surface 24a of the piston 24 comes into contact with the end wall 26a of the measuring chamber 26 and the movement of the piston 24 is completed, the electromagnetic solenoid 20 is demagnetized by the control device 14 and the main valve 13 is closed. Thereby, the supply of the water accumulated in the measuring chamber 26 to the cylinder ends.

  When the supply of water from the measuring chamber 26 is completed, accumulation of water in the measuring chamber 26 is subsequently started. That is, the electromagnetic valve 12 is opened under the control of the control device 14 in a state where the main valve 13 is closed. The electromagnetic valve 12 is maintained in an open state only during the valve opening time set based on the next operation amount based on the command from the control device 14, and during this time, the piston 24 moves to measure. Water is accumulated in the chamber 26. Although both the pressure chamber 25 and the measuring chamber 26 are in communication with the pressure source unit 3, the piston 24 moves in the direction in which water is accumulated in the measuring chamber 26 by the biasing force of the spring 28. Therefore, the opening / closing operation of the electromagnetic valve 12 is controlled by proportional integral control based on the detection signal of the position sensor 27 and the command value of the water supply amount, and the position of the piston 24 at the time of accumulation is controlled. After the accumulation of water in the measuring chamber 26 is completed, the above-described cycle is repeated based on the control by the control device 14.

  As described above, according to the metering mechanism 1, the moving speed of the piston 24 during accumulation is set to be slowed by the delay means, and the opening / closing operation of the solenoid valve 12 is performed by the control device 14 by proportional integral control during accumulation. The position of the piston 24 during accumulation is controlled. For this reason, the amount of water supplied from the injection valve 4 to the cylinder and stored in the measuring chamber 26 is accurately controlled. Further, since the control device 14 performs proportional-integral control based on the piston position detection signal and the command value to control the piston position, the water supply amount accumulated in the measuring chamber 26 even when the command value changes. Can quickly follow the change in the command value. Therefore, position control in the measuring cylinder 11 can be easily performed, and more accurate control of the water supply amount into the cylinder can be realized.

  Further, according to the metering mechanism 1, when the actually supplied supply amount approaches the target value of the fluid supply amount, the dead zone setting device converts the difference value to a value close to zero value and outputs it to the output. Since control can be performed based on this, it is possible to suppress the occurrence of hunting due to the occurrence of overshoot or the like and the control system becoming unstable.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

It is a circuit block diagram of the engine fluid supply apparatus in which the metering mechanism of the engine fluid supply apparatus according to an embodiment of the present invention is used. It is a schematic diagram of the fluid supply apparatus for engines shown in FIG. It is a control conceptual diagram explaining the process in the control apparatus of the measurement mechanism shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring mechanism of engine fluid supply apparatus 2 Engine fluid supply apparatus 3 Pressure source unit 4 Injection valve 11 Measuring cylinder 12 Electromagnetic valve 13 Main valve 14 Control apparatus (control part)
24 Piston 25 Pressure chamber 26 Weighing chamber 27 Position sensor (detector)

Claims (2)

Between the pressure source unit that supplies the fluid for injection and the injection valve that injects the fluid supplied from the pressure source unit through the injection port formed in the cylinder of the engine and supplies the fluid into the cylinder. A metering mechanism for an engine fluid supply device that controls a fluid supply amount into a cylinder,
A measuring cylinder disposed between the pressure source unit and the injection valve and having a piston disposed therein;
A pressure chamber provided in the measuring cylinder and partitioned by the piston; the pressure chamber connected to the pressure source unit; the pressure valve connected to the injection valve and via an electromagnetic valve; Said weighing chamber connected to a source unit;
A detector for detecting the position of the piston;
A control unit to which a detection signal based on a detection result of the position of the piston by the detector and a command value corresponding to a target value of the fluid supply amount are input;
Delay means for setting the moving speed of the piston to be slower at the time of accumulation for accumulating fluid in the metering chamber than at the time of discharge for supplying fluid from the metering chamber to the injection valve;
With
The controller controls the position of the piston at the time of accumulation by controlling the opening / closing operation of the solenoid valve by proportional-integral control based on the detection signal and the command value at the time of accumulation. Measuring mechanism for engine fluid supply device. The control unit calculates a difference calculated based on the command value and the detection signal, and when the difference value is close to a zero value, the difference value becomes closer to a zero value. 2. The metering of the engine fluid supply device according to claim 1, further comprising: a dead band setting device that converts the electromagnetic valve into an open / close state, and controlling the opening / closing operation of the solenoid valve by proportional-integral control based on an output from the dead band setting device. mechanism.

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