JPH11294343A - Control device of electromagnetic type pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of electromagnetic type pump which can reduce the collision sound of a needle and a magnetic body. SOLUTION: In a control device 6 of an electromagnetic type pump 3 to lift a needle by the exciting action of a coil, and to suck and discharge a fluid, a current value control means 12 to control the current value fed to the coil in order to make the driving force at the lifting final period almost equal to or smaller than the driving force at the lifting initial period, according to the lift of the needle by the exciting action, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electromagnetic pump for sucking and discharging a fluid by using the exciting action of a coil.

[0002]

2. Description of the Related Art Various pumps are used to pump a fluid. As one of these pumps, a diaphragm pump that drives a diaphragm to pump a fluid is known. In this diaphragm pump, there are a rotary driving unit and a reciprocating driving unit as means for driving the diaphragm. In the rotary drive unit, for example, the diaphragm is driven by a rotary driving force of a motor or the like. In this case, however, the configuration of the power transmission unit to the diaphragm becomes complicated, and there is a problem that the device becomes large. For this reason, emphasis is placed on reciprocating drive means that can directly drive the diaphragm. As the reciprocating drive means, a large number of electromagnetic drive systems having a simple configuration are used, and an example of an electromagnetic pump employing this electromagnetic drive system is disclosed in
No. 108003.

[0003]

The reciprocating drive means of the electromagnetic pump disclosed in the above-mentioned publication mainly comprises a mover for directly driving the diaphragm and a coil for reciprocally driving the mover. I have. The mover is driven by the exciting action of the coil. In order to excite the coil, a predetermined amount of power is supplied to the coil, and this power supply amount is substantially constant while the mover is driven.

For this reason, as shown by line A in FIG. 7, when the mover moves, as the mover approaches the magnetic body disposed opposite thereto, the distance between the mover and the magnetic body increases. Since it becomes smaller, the driving force (magnetic force) acting on the mover increases. Accordingly, the mover is suddenly accelerated by the increase in the driving force and collides with the magnetic body, so that a collision sound is generated. In the characteristic diagram shown in FIG. 7, the horizontal axis represents the movement of the mover, and the vertical axis represents the driving force acting on the mover. In the figure, line A represents the characteristic of the driving force to the mover due to the exciting action of the coil, line B represents the characteristic of the pressure load due to the fluid pressure (in this case, the constant pressure load), and line C represents the line B Shows the characteristics of the force obtained by adding the biasing force of the spring. Therefore, an object of the present invention is to provide a control device for an electromagnetic pump that can reduce the collision sound between the mover and the magnetic body.

[0005]

According to the first aspect of the present invention, the current value control means determines that the driving force at the end of the displacement of the movable element with the displacement of the movable element toward the fluid discharge side by the excitation action. Since the current value is controlled so as to be substantially equal to or smaller than the initial drive force of the mover, the drive force acting on the mover is weakened at the end of movement of the mover,
Sudden acceleration is suppressed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 indicates a fuel injection device of an automobile, for example, a common rail system.
The common rail system 1 includes a common rail 2 having a plurality of injectors 2a, an electromagnetic reciprocating pump 3 for pressure-feeding fuel to the common rail 2, and a fuel pressure sensor that is provided downstream of the common rail 2 in a fuel supply path and detects fuel pressure. 4, a regulator 5 for adjusting the fuel pressure of the common rail 2, and a control device 6 for controlling the supply pressure and supply amount of the fuel by the electromagnetic reciprocating pump 3. The common rail system 1 comprehensively controls a fuel injection amount, a fuel injection timing, an injection pressure, and the like with a control device (not shown) according to the state of the engine (engine speed, accelerator opening, cooling water temperature, and the like), and controls the engine. Operate in optimal condition.

[0007] The control device 6 is based on a TPS signal from a throttle position sensor 7 (hereinafter referred to as TPS) for detecting the accelerator opening and a Ne signal from a rotation speed detection sensor 8 for detecting the engine speed. EC for calculating the current value to be supplied to the electromagnetic reciprocating pump 3 and its frequency
U9 and a driving means 10 for supplying power to the electromagnetic reciprocating pump 3 based on the current value and the frequency calculated by the ECU 9. The ECU 9 is also connected to the fuel pressure sensor 4 and receives a signal from the sensor 4. A power supply 11 for driving the electromagnetic reciprocating pump 3 is connected to the driving means 10. The driving means 10 is provided with a coil 28 (described later) of the electromagnetic reciprocating pump 3.
And a current value control means 12 for controlling a current value to be supplied to the power supply. As shown in FIG. 2, the electromagnetic reciprocating pump 3
The outer shape is constituted by a first housing 15 and a second housing 16 which is airtightly coupled to the first housing 15.

An end face of the first housing 15 connected to the second housing 16 is provided with a recess 15a, and an annular member 17 adapted to the shape of the recess 15a is provided in the recess 15a. It is fitted via a member 18. The annular member 17 is formed of a magnetic material, for example, an iron material. At a substantially central portion of the annular member 17, a hole 17b is provided except for a pedestal 17a for receiving one end of a spring 24 described later. The hole 17b has a step and forms a part of the working chamber 19 for pumping fuel. First
A fuel suction passage 20 for supplying fuel from a fuel tank (not shown) to a working chamber 19 described later;
A fuel pressure feed path 21 for feeding the fuel pressurized in the working chamber 19 to the common rail 2 is provided.

A valve corresponding to the opening of the fuel intake passage 20 of the valve member 18 is provided with an intake valve 18a that allows only the flow of fuel from the fuel intake passage 20 to the inside of the working chamber 19. In addition, a discharge valve 18 b that allows only the flow of fuel from the inside of the working chamber 19 to the fuel pressure transmission path 21 is provided at a position corresponding to the opening of the fuel pressure transmission path 21 of the valve member 18. The second housing 16 is composed of a cylindrical outer housing 16a constituting the outer side thereof, and an inner housing 16b disposed inside the outer housing 16a. The inner housing 16b is a substantially cup-shaped cylindrical body made of an iron material, and its opening is formed in the working chamber 1.
9.

A cylindrical cylinder 22 is inserted into the inside of the inner housing 16b, and a plunger 23 as a movable element made of a magnetic material, for example, an iron material is slidable inside the cylinder 22. It is inserted in.
One end face of the plunger 23, that is, the inner housing 1
The end surface corresponding to the opening of 6b and the inner surface of the cylinder 22 also constitute a part of the working chamber 19. A spring 24 for urging the plunger 23 toward the bottom of the inner housing 16b is provided between the annular member 17 and the plunger 23. Due to this spring 24, the plunger 23 always
It is urged to the bottom of the inner housing 16b.

When the plunger 23 moves toward the bottom of the inner housing 16b, the collision between the other end of the plunger 23 and the bottom of the inner housing 16b occurs between the other end of the plunger 23 and the bottom of the inner housing 16b. A spring 25 for reducing the pressure is provided. A fuel release passage 26 communicating with a space defined by the other end surface of the plunger 23 and the bottom of the inner housing 16b is provided at the bottom of the inner housing 16b.
The leaked fuel is returned to a fuel tank (not shown) through a fuel return path (not shown).

A flange is provided on each of the periphery of the opening and the bottom of the inner housing 16b, and these flanges are in contact with the inner peripheral surface of the outer housing 16a. A coil 28 for driving the plunger 23 is provided in a space covered by the inner peripheral surface of the outer housing 16a and the outer peripheral surface and the flange of the inner housing 16b. The coil 28 is connected to the driving means 10.
Next, the operation of the above-described electromagnetic reciprocating pump 3 will be described.

When power is supplied to the coil 28, the exciting action of the coil 28 causes the plunger 23 to move upward in the drawing against the urging force of the spring 24. The movement of the plunger 23 reduces the volume of the working chamber 19,
The fuel pressure inside rises. Due to this increase in fuel pressure,
In the drawing, the discharge valve 18b is opened as shown by the two-dot chain line, and the pressurized fuel in the working chamber 19 is discharged to the fuel pressure feed path 21 via the discharge valve 18b.

When the power supply to the coil 28 is interrupted, the exciting action of the coil 28 is also stopped, and the urging force of the spring 24
The plunger 23 moves downward in the figure. Plunger 2
As the 3 moves, the volume of the working chamber 19 increases, and the fuel pressure in the working chamber 19 decreases. Due to this decrease in fuel pressure, the intake valve 18
a is opened, and fuel is drawn into the working chamber 19 from the fuel suction path 20 via the suction valve 18a. At this time, the plunger 23 pushes the inner housing 16b
Of the plunger 23, the collision of the other end of the plunger 23 with the bottom of the inner housing 16b can be reduced, and the collision noise can be reduced. Coil 2 described above
By repeatedly performing the power supply control to the power supply 8, the fuel suction operation and the fuel discharge operation are repeatedly performed in the working chamber 19, and the pressurized fuel is supplied to the common rail 2.

Here, the current value control when the current value control means 12 supplies power to the coil 28, that is, when the coil is excited will be described in detail. The driving force (magnetic force) acting on the plunger 23 by the exciting action of the coil 28 is
It becomes larger as the plunger 23 approaches the annular member 17. On the other hand, the driving force due to the exciting action of the coil 28 is
It can be adjusted by the current value supplied to the coil 28. Therefore, when supplying power to the coil 28, the current value supplied to the coil 28 is controlled such that the driving force at the end of the lift is substantially equal to or smaller than the driving force at the beginning of the lift according to the displacement of the plunger 23, that is, the lift. I do. in this way,
By controlling the current value according to the lift of the plunger 23, the plunger 2
The driving force acting on 3 is weakened, and the sudden acceleration of the plunger 23 at the end of the lift is suppressed. Therefore, the collision force when the plunger 23 collides with the annular member 17 can be reduced, and the collision sound of the plunger 23 with the annular member 17 can be reduced. In addition, breakage of the plunger 23 can be prevented.

FIG. 3 is a characteristic diagram showing a change in a current value of power supply to the coil 28 with respect to a change in the lift amount of the plunger 23.
(A). In the figure, the horizontal axis indicates the lift amount of the plunger 23, and the vertical axis indicates the current value for supplying power to the coil 28. In the drawing, reference numeral C1 indicates the characteristic of the current value. FIG. 3B is a characteristic diagram showing a change in driving force acting on the plunger 23 with respect to a change in the lift amount of the plunger 23 when power is supplied to the coil 28 with a current value having the characteristic shown in FIG. Show. In the figure, the plunger 2 is on the horizontal axis.
The lift amount of No. 3 is shown on the vertical axis, and the driving force acting on the plunger 23 is shown on the vertical axis. In the figure, reference symbol D1 indicates the plunger 23.
The symbol E indicates the force obtained by adding the pressure load by the fuel and the urging force of the spring 24.

As shown in FIG. 3A, the value of the current supplied to the coil 28 is appropriately adjusted, for example, by gradually decreasing the current value in accordance with the amount of lift of the plunger 23, as shown in FIG. 3B. As described above, it is also possible to maintain a substantially constant difference between the forces D1 and E during the lift of the plunger 23. Note that the driving force of the plunger 23 is always set to exceed the force obtained by adding the pressure load by the fuel and the urging force of the spring 24. By maintaining the difference between the forces D1 and E substantially constant, the lift of the plunger 23 can be stabilized, and optimal power supply can be performed.
Since unnecessary power supply is omitted, power saving can be achieved.

Further, by utilizing the characteristic that the driving force acting on the coil 28 can be adjusted by adjusting the value of the current supplied to the coil 28, as shown by a characteristic line C2 in FIG. When the rate of decrease of the current value according to the lift amount of the plunger 23 is made larger than the characteristic line C1,
As shown by a characteristic line D2 in FIG.
During the lift, the driving force acting on the coil 28 becomes lower than the force obtained by adding the pressure load by the fuel and the urging force of the spring 24. In this case, the plunger 23 stops immediately after the driving force acting on the coil 28, the pressure load by the fuel, and the force obtained by adding the urging force of the spring 24 become substantially equal. By stopping the plunger 23 halfway, the fuel discharge amount decreases. Therefore, during the lift of the plunger 23, the fuel discharge amount is reduced by decreasing the current value so that the driving force acting on the coil 28 is less than the force obtained by adding the pressure load by the fuel and the urging force of the spring 24. Can be adjusted.

Referring to FIG. 3B, on the characteristic line D1, until the plunger 23 collides with the annular member 17, the driving force acting on the plunger applies the pressure load by the fuel and the urging force of the spring 24. Therefore, the lift amount of the plunger 23 is indicated by a symbol F1 in the drawing. On the other hand, in the characteristic line D2, before the plunger 23 collides with the annular member 17, the driving force acting on the plunger becomes smaller than the force obtained by adding the pressure load by the fuel and the urging force of the spring 24, and the lift amount of the plunger 23 is increased. Is a symbol F2 in the figure.
Becomes When the lift amount F1 of the plunger 23 is compared with the lift amount F2, the lift amount F2 becomes smaller than the lift amount F1, and the fuel discharge amount also becomes smaller.

Next, a second embodiment will be described.
The above-described electromagnetic reciprocating pump 3 suctions and discharges fuel by the reciprocating movement of the plunger 23 in the cylinder 22, but due to its nature, pulsation of fuel pressure (hereinafter simply referred to as fuel pressure pulsation) occurs. . However, by using the above-described control in which the lift amount of the mover is made variable, the fuel pressure pulsation can also be controlled. In the present embodiment, control of the fuel pressure pulsation will be described. As shown in FIG. 4, the fuel injection amount in the common rail system 1 shown in FIG. 1 is mainly determined according to the TPS signal and the Ne signal. In the figure, a characteristic line G indicates a constant line of the fuel injection amount per time.

The control of the fuel discharge amount of the electromagnetic reciprocating pump 3 based on the characteristic of the fuel injection amount shown in FIG. 4 is performed based on the flowchart shown in FIG. First, step S
In step 1, the ECU 9 reads the driving information, that is, the TPS signal and the Ne signal from the TPS 7 and the rotation speed detection sensor 8, respectively. Next, the process proceeds to step S2, in which a current value and a frequency corresponding to the TPS signal and the Ne signal are calculated from a control map described later. Further, the process proceeds to step S3, in which the drive unit 10 supplies power to the electromagnetic reciprocating pump 3 based on the current value and the frequency calculated in step S2.

Here, the control map will be described. The control map shown in FIG. 6 is for controlling the fuel discharge amount under four conditions of, for example, constant current value, constant frequency, pulsation optimization, and frequency / Ne synchronization. The characteristics of the fuel pressure pulsation differ from each other. This control map is stored in the ECU 9 in advance. Hereinafter, the characteristics of the fuel pressure pulsation under each condition will be described with reference to FIG. First, the case where the current value is constant will be described. In this case, the constant current amount means that the current waveform of the discharge cycle is the same throughout a plurality of cycles.
It does not mean that a constant current flows during the lift of the plunger. In this case, since the current value is constant, the frequency H is increased or decreased to control the fuel discharge amount. That is,
When the required fuel injection amount is small, the frequency H is reduced to reduce the fuel discharge amount, and when the required fuel injection amount is large, the frequency H is increased to increase the fuel discharge amount. Therefore, by appropriately adjusting the frequency H, the fuel pressure pulsation becomes substantially constant even when Ne increases.

Next, the case where the frequency is constant will be described. In this case, since the frequency is fixed, the current value I is increased or decreased to control the fuel discharge amount. That is, when the required fuel injection amount is small, the current value I is reduced, and the plunger lift amount is reduced to reduce the fuel discharge amount. When the required fuel injection amount is large, the current value I is increased and the plunger lift is increased. Increase the fuel discharge amount by increasing the amount. Therefore, by appropriately adjusting the current value I, the fuel pressure pulsation increases substantially in proportion to the increase in Ne.

Further, the case of pulsation optimization will be described. In this case, the frequency H and the current value I are controlled to be large, medium and small, respectively, to control the fuel discharge amount. That is, when the required fuel injection amount is small, the frequency H is set to a medium level, and
When the fuel injection amount is reduced by reducing the current value I and the required fuel injection amount is medium, the frequency H is increased, and the current value I is reduced to make the fuel discharge amount medium. When the fuel injection amount is large, the frequency H is medium and the current value I is increased to increase the fuel discharge amount. Therefore, by appropriately adjusting the frequency H and the current value I, the fuel pressure pulsation becomes substantially constant at a low level even when Ne increases, but when the Ne exceeds a predetermined value, the fuel pressure pulsation sharply increases.

Further, the case of frequency / Ne synchronization will be described. In this case, the frequency H is synchronized with Ne,
The fuel discharge amount is controlled by increasing or decreasing the current value I. That is, the frequency H is represented by the following equation: H = (Ne / 60) × (number of cylinders / 2) × (1,2,3,3)
Ii) When the required fuel injection amount is small, the current value I is reduced to reduce the fuel discharge amount, and when the required fuel injection amount is large, the current value I is set to a medium value and the fuel discharge amount is increased.
Therefore, by appropriately adjusting the frequency H and the current value I, the fuel pressure pulsation gradually increases as Ne increases. The advantage in this case is that the frequency H is synchronized with the rotation speed Ne, so that the pulsation order can be kept constant. Further, by setting H to be an integral multiple of (the number of cylinders / 2), the pulsation amplitude can be improved. Even if the fuel injection amount increases, it is possible to suppress the variation in the injection amount for each cylinder.

Therefore, depending on each condition, the current value and / or
Or, by adjusting the frequency, after satisfying the condition of performing discharge according to the required fuel injection amount,
The fuel pressure pulsation can be controlled, and the fuel pressure pulsation can be reduced. In each of the embodiments described above, the case where the electromagnetic reciprocating pump 3 is used as a fuel pump in a fuel injection device of an automobile has been described. However, the present invention is not limited to this case. The present invention can be applied to a pump that sucks and discharges a fluid to pump the fluid. In addition, the case where the fluid is a vehicle fuel has been described. However, the present invention is not limited to this, and the same effect as described above can be obtained even with a gas such as air or a liquid such as water.

Further, the electromagnetic reciprocating pump in each of the above-described embodiments is a single action in which one reciprocation of the plunger 23 performs one fuel suction / discharge, but working chambers are provided at both ends of the plunger. The electromagnetic pump control device of the present invention may be applied to a double-action electromagnetic reciprocating pump that performs two times of fuel suction and discharge for each reciprocating motion of the plunger. Further, the control device of the electromagnetic pump of the present invention can be applied to an electromagnetic reciprocating pump for directly driving a diaphragm disclosed in Japanese Patent Application Laid-Open No. 54-108003. The same effect as described above can be obtained.

[0028]

As described above, according to the first aspect of the present invention, at the end of the displacement of the mover, the driving force acting on the mover is weakened, and the sudden acceleration of the mover is suppressed. Therefore, it is possible to reduce the sound of collision of the mover with the magnetic body.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a common rail system according to a first embodiment.

FIG. 2 is an enlarged vertical sectional view of the electromagnetic reciprocating pump according to the first embodiment.

3A and 3B are characteristic diagrams illustrating a relationship between a current value supplied to a coil and a driving force acting on a plunger. FIG. 3A illustrates a change in a current value to the coil with respect to a change in a lift amount of the plunger, and FIG. The parentheses indicate changes in the driving force acting on the plunger with respect to changes in the lift amount of the plunger.

FIG. 4 is a characteristic diagram showing characteristics of a fuel injection amount in a common rail system according to a TPS signal and a Ne signal.

FIG. 5 is a flowchart showing the control of the current value and the frequency to the electromagnetic reciprocating pump.

FIG. 6 is a control map for determining a current value and a frequency.

FIG. 7 is a characteristic diagram showing a change in driving force acting on the mover when the mover moves in a conventional case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Common rail system 2 Common rail 3 Electromagnetic reciprocating pump 6 Control device 7 TPS 8 Rotation speed detection sensor 9 ECU 10 Driving means 12 Current value control means 19 Working chamber 22 Cylinder 23 Plunger (movable element) 28 Coil

Claims (1)

[Claims] 1. A control device for an electromagnetic pump for reciprocating a movable element by an exciting action of a coil and sucking and discharging a fluid, wherein the movable element is displaced to the fluid discharge side by the exciting action. An electromagnetic pump having current value control means for controlling a current value supplied to the coil so that the driving force at the end of displacement of the movable element is substantially equal to or smaller than the driving force of the movable element at the beginning of displacement Control device.