JP3921954B2 - Solenoid lift adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solenoid lift amount adjusting method for adjusting an amount by which a solenoid sucks and lifts an armature in an injector or the like of a diesel engine.
[0002]
[Prior art]
There is a device in which a current is passed through a solenoid coil to generate a magnetic attractive force, the armature is lifted (lifted) by the magnetic attractive force, and some action is performed according to the lift amount (lift amount). Some types of diesel engine injectors use such devices. Hereinafter, this will be described as an example.
[0003]
FIG. 3 is a diagram showing a schematic configuration of a conventional injector. In FIG. 3, 1 is an injector, 2 is a magnetic core, 3 is a spring, 4 is a fuel discharge path, 5 is a branch path, 5A is an inlet orifice, 6 is a fuel supply path, 7 is a branch path, 8 is an injector body, 9 Is a needle, 9A is a needle head, 9B is a needle tip, 9C is a needle return spring, 10 is a nozzle, 11 is a solenoid coil, 12 is an operating power terminal, 13 is an air gap, 14 is an armature, 15 is a fuel chamber, Reference numeral 16 denotes a discharge path, 16A denotes an outlet orifice, 17 denotes a control chamber, and 18 denotes a needle movable hole.
Fuel is supplied from the fuel supply passage 6 on the left side and injected from the nozzle 10 at the lower end to the engine (not shown). First, the configuration of the injector 1 will be described.
[0004]
The injector body 8 forms the outer shell of the injector 1. A magnetic core 2 and a solenoid coil 11 are provided on the upper portion of the injector 1, and an armature 14 that is springed by a spring 3 is provided so as to face the magnetic core 2. Due to the bullet, an air gap 13 is generated between the magnetic core 2 and the armature 14.
A needle movable hole 18 is provided at the center of the injector 1, and a needle 9 is movably inserted therein. The needle head 9 </ b> A is in contact with the inner wall of the needle movable hole 18 so as to be liquid-tight. The needle return spring 9 </ b> C is for repelling the needle 9 downward in order to close the nozzle 10. When the needle 9 is lowered to the lower end, the needle tip 9B closes the nozzle 10. When the needle 9 is pulled up, the nozzle 10 is opened.
[0005]
A portion of the needle movable hole 18 above the needle head 9 </ b> A is called a control chamber 17. The fuel supply path 6 is divided into branch paths 5 and 7 on the way, the branch path 5 goes to the control chamber 17, and the branch path 7 goes to the needle movable hole 18 below the needle head 9A. The branch path 5 has a small diameter immediately before the control chamber 17 and serves as an inlet orifice 5A.
The fuel supply path 6 is supplied with fuel that has been pressurized at a pressure accumulation chamber (common rail). This high-pressure fuel is supplied to both sides of the needle head 9A via the branch paths 5 and 7.
[0006]
The control chamber 17 communicates with the fuel chamber 15 via the discharge passage 16, but when the armature 14 is springed downward as shown in the figure by the spring 3, its outlet is closed. The discharge passage 16 has a diameter that is narrowed immediately before the fuel chamber 15 and serves as an outlet orifice 16A (note that the diameter of the outlet orifice 16A is larger than the diameter of the inlet orifice 5A).
When the armature 14 is pulled up, fuel flows out from the control chamber 17 to the fuel chamber 15. This fuel is returned to the fuel tank (not shown) through the fuel discharge path 4.
[0007]
Next, the injection operation by the injector 1 will be described.
(1) When the solenoid coil 11 is not energized At this time, since the solenoid coil 11 is not energized, the armature 14 is not attracted. Therefore, the armature 14 is springed downward by the spring 3 and closes the outlet orifice 16A.
In such a state, the high-pressure fuel put into the fuel supply path 6 from the pressure accumulating chamber is sent to the control chamber 17 through the branch path 5 and passes through the branch path 7 in the portion below the needle head 9A. It is sent to the needle movable hole 18. Because the needle tip spring 9C abuts against the valve seat and closes the nozzle 10 due to the downward spring by the needle return spring 9C, the fuel does not flow in the tip direction from the contact portion, and the surface of the needle tip portion 9B No hydraulic pressure is applied (if the hydraulic pressure is applied to this surface, it becomes a pressure to push the needle 9 upward).
Therefore, when the hydraulic pressure applied downward with respect to the entire needle 9 is compared with the hydraulic pressure applied upward, the downward pressure is increased by the hydraulic pressure applied to the valve seat. As a result, in addition to the downward elastic force of the needle return spring 9C, a downward pressure due to the hydraulic pressure difference is applied to the needle 9, and the nozzle 10 is kept closed (no fuel is injected). At this time, the needle head 9A just plays the role of a piston.
[0008]
(2) When the solenoid coil 11 is energized When the solenoid coil 11 is energized, the armature 14 is attracted to the magnetic core 2 against the elastic force of the spring 3. That is, the armature 14 is somewhat lifted (lifted). Then, the outlet of the outlet orifice 16A is opened, the fuel in the control chamber 17 flows out to the fuel chamber 15, and the pressure in the control chamber 17 decreases.
As a result, the pressure balance between the top and bottom of the needle head 9A is lost, and the needle 9 is moved upward. As a result, the needle tip 9 </ b> B that has blocked the nozzle 10 is also raised, so that fuel is injected from the nozzle 10.
When the energization of the solenoid coil 11 is finished, the armature 14 that has been lifted is repelled downward again to close the outlet orifice 16A. Therefore, the needle 9 is moved downward and the nozzle 10 is closed.
[0009]
Although the injection operation is performed as described above, it is known that the injection amount and the like are greatly influenced by the lift amount of the armature 14 when the solenoid coil 11 is energized. This lift amount varies depending on the magnetic characteristics of the solenoid. That is, there are several parts constituting the solenoid part (for example, the solenoid coil 11, the magnetic core 2, the armature 14, the spring 3, etc.), and those used for the same injector are manufactured in the same manner. However, there is inevitably variation among individuals due to processing distortions. Therefore, there are variations in the magnetic characteristics of the solenoid, and the lift amount is not the same.
[0010]
Therefore, in order to perform a desired injection operation, it is necessary to adjust the lift amount after assembly of the injector 1.
Conventionally, after actually injecting, it is indirectly determined whether or not the lift amount is appropriate from the injection characteristics, and when it is not appropriate, the lift amount is adjusted to be small or large. Specifically, a portion that affects the magnetic characteristics of the solenoid is adjusted. For example, the size of the air gap 13 is adjusted by inserting or removing a shim.
For example, Japanese Patent Laid-Open No. 9-217644 discloses a conventional document related to a fuel injection injector.
[0011]
[Problems to be solved by the invention]
In the conventional solenoid lift amount adjusting method described above, since the lift amount is estimated from the injection characteristics of the injector, the variation is large and it cannot be estimated accurately. For this reason, the lift amount is not adjusted properly, the magnetic characteristics of the solenoid remain uneven, and the injection characteristics also vary.
As described above, in addition to making adjustments by taking measures to change the physical structure, there is also an idea of adjusting the lift amount by changing the energization amount to the solenoid coil 11. Since energy would be required, it was not preferable.
An object of the present invention is to solve the above-described problems.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, the position of the armature that is spring-loaded from the magnetic core of the solenoid and is separated from the air gap before the solenoid coil is energized and lifted is energized. In a solenoid lift amount adjustment method for adjusting a lift amount, which is a difference from a position after being lifted, a first process of measuring the inductance of the solenoid before the lift and measuring the inductance of the solenoid after the lift, and the measurement By applying the inductance before the lift and the inductance after the lift to a map showing the relationship between the solenoid inductance and the air gap, the second process for obtaining the lift amount and the air so that the obtained lift amount becomes a predetermined value. And a third step of adjusting the gap.
[0013]
(Work)
Solenoid inductance is measured, and the lift amount of the solenoid is obtained using a map that shows the relationship between the inductance and the air gap. Therefore, even if there are variations in the magnetic characteristics of the solenoid, the influence is incorporated into the shape. Thus, the lift amount can be obtained more accurately than before. Since the air gap is adjusted so that the obtained lift amount becomes a predetermined appropriate value, variations in magnetic characteristics are reduced. If the solenoid used in the injector is adjusted in this way, variations in the injection characteristics between the injectors are reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view showing an injector when the solenoid lift amount adjusting method of the present invention is carried out. Reference numerals correspond to those in FIG. 3, and 20 is a measurement terminal. The measurement terminal 20 is a terminal for measuring the inductance of the solenoid.
In the present invention, the relationship between the solenoid inductance and the air gap is obtained in advance as a map. Then, after the injector 1 is assembled, the inductance before and after the armature 14 is lifted is measured, and the air gap at each time is obtained in light of the map. Then, since the lift amount is naturally obtained, the lift amount is adjusted so that it becomes a predetermined appropriate value. After this adjustment, the inductance is measured again to calculate the lift amount, and the lift amount adjustment is repeated.
[0015]
FIG. 4 is a diagram illustrating the relationship between the air gap and the inductance of the solenoid. The vertical axis represents the inductance, and the horizontal axis represents the air gap. Curve A is a curve showing the relationship between the inductance of the solenoid and the air gap. This relationship can be obtained in advance and can be held in the form of a map.
Referring to FIG. 1, the armature 14 is in a state before being lifted. At this time, the inductance, that is, the inductance before lifting, is measured, and the inductance after being lifted by energizing the solenoid coil 11, that is, after lifting. Measure the inductance.
[0016]
Measurements, the lift before inductance = L _S, assuming that a lift after inductance = L _E, by following these as fitting dotted arrow in FIG. 4, the air gap when each determined as follows It is done.
Air gap before lift = G _S
Air gap after lift = G _E
The difference between the two is the lift amount. That is, the lift amount G _SE = G _S −G _E.
FIG. 2 is a diagram illustrating a physical relationship between the air gap and the lift amount in the injector 1. FIG. 2 (1) represents the state before the lift, and FIG. 2 (2) represents the state after the lift. The lift amount _GSE is the size shown in the figure.
[0017]
In the present invention, the lift amount _GSE is obtained in FIG. 4 by measuring the inductance, but the lift amount _GSE can be obtained with high accuracy by preparing a map with high accuracy. In addition, even if the solenoid components vary, and even if the solenoid magnetic characteristics vary, the inductance is measured in a state in which all these variations are incorporated.
[0018]
Since the measurement inductance and lift G _SE obtained by the map is accurate, adjustment work so that the lift amount is appropriately sized based on it be performed (eg, adjustment by shim), the variation of the magnetic properties Is reduced as compared with the prior art, and variations in the injection characteristics of the injector are also reduced. The proper lift amount of the solenoid varies depending on the type of the injector. For example, the proper value in this injector can be obtained in advance, such as the size in the range of G _{1 to} G ₂ .
Needless to say, the method of the present invention can be used not only for the solenoid of the injector, but also for the solenoids of other devices (eg, actuators).
[0019]
【The invention's effect】
As described above, according to the solenoid lift amount adjusting method of the present invention, the solenoid inductance is measured, and the solenoid lift amount is obtained using the map showing the relationship between the inductance and the air gap. Even if there is a variation in characteristics, the lift amount can be obtained more accurately than in the past, in a form that incorporates these effects.
Since the air gap is adjusted so that the lift amount thus determined becomes a predetermined appropriate value, variations in magnetic characteristics are reduced. By adjusting the solenoid used in the injector in this way, it is possible to reduce variations in injection characteristics due to variations in solenoid magnetic characteristics.
[Brief description of the drawings]
FIG. 1 is a view showing an injector when the solenoid lift amount adjusting method of the present invention is carried out. FIG. 2 is a view showing a physical relationship between an air gap and a lift amount in the injector. FIG. 3 is a schematic configuration of a conventional injector. Figure [Figure 4] Figure showing the relationship between air gap and inductance [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Injector, 2 ... Magnetic core, 3 ... Spring, 4 ... Fuel discharge path, 5 ... Branching path, 5A ... Inlet orifice, 6 ... Fuel supply path, 7 ... Branching path, 8 ... Injector body, 9 ... Needle, 9A ... Needle head, 9B ... Needle tip, 9C ... Needle return spring, 10 ... Nozzle 1, 11 ... Solenoid coil, 12 ... Operating power supply terminal, 13 ... Air gap, 14 ... Armature, 15 ... Outlet orifice, 16 ... Discharge Path 17 control room 18 needle movable hole 20 measurement terminal

Claims (1)

The difference between the position of the armature, which is springed from the magnetic core of the solenoid and separated from the air gap, before the solenoid coil is energized and lifted, and the position after it is energized and lifted In the solenoid lift amount adjustment method for adjusting a certain lift amount,
A first step of measuring the inductance of the solenoid before lift and measuring the inductance of the solenoid after lift;
Applying the measured inductance before lift and inductance after lift to a map showing the relationship between solenoid inductance and the air gap, and a second process for obtaining the lift amount;
A method for adjusting a solenoid lift amount, comprising: a third step of adjusting an air gap so that the obtained lift amount becomes a predetermined value.

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