KR20150067504A - Method for assembling injector of engine for vehicle - Google Patents

Abstract

The present invention relates to a method for assembling an injector of an engine for a vehicle. A valve lift is temporarily set to close to a designed value and the present invention repeats a welding work of a carrier and a valve seat connection unit to gradually reduce difference between the designed value and the measured value in order to more accurately set the valve lift of an injector.

Description

Technical Field [0001] The present invention relates to a method for assembling an injector of an automobile engine,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of assembling an injector of an automobile engine, and more particularly, to a method of assembling an injector of an automobile engine capable of accurately setting a valve lift.

BACKGROUND OF THE INVENTION [0002] A recent automobile engine is a direct injection system in which fuel is directly injected into each cylinder. For this purpose, an injector is provided for each cylinder.

Further, the operation of the injector is electronically controlled by the engine control unit (ECU).

The engine control unit detects the engine operation status such as intake air amount, engine rotation speed and throttle valve opening through the sensor, calculates the fuel supply amount corresponding thereto, and controls the opening time of the injector so that the optimum amount of fuel Timely supply.

The injector is controlled to be supplied with current by the engine control unit. When the current is supplied, the built-in coil assembly and the magnetized parts in contact therewith are excited to pull the needle assembly to open the injection hole. When the current supply is stopped, The needle assembly is returned to close the injection hole.

Therefore, as described above, the fuel injection amount is controlled by controlling the current supply to regulate the injection opening time of the injector.

An example of the injector including the above configuration is disclosed in Korean Patent Publication No. 10-2013-0065352.

1, the injector includes an upper body 10, a connector 20, a carrier 30, and an upper body 10, which form a flow path, as shown in Fig. A needle assembly 40 provided inside the carrier 30, a coil assembly 50 provided on the outer periphery of the connector 20, a plastic plate 50 for overmolding the coil assembly 50 and integrally forming a current connector 61 And includes a housing 60 and a metal housing 70 that surrounds and protects the outer periphery of the plastic housing 60.

The connector 20 is connected to a lower side of the upper body 10 as a cylindrical part in which the upper body 10, the connector 20 and the carrier 30, The carrier 30 is connected to the lower side of the carrier 30.

A cylindrical stopper 21 is fixedly installed at an intermediate portion of the connector 20 and a return spring 22 is provided at a lower portion of the stopper 21.

The needle assembly 40 is first inserted into the interior of the carrier 30 before the carrier 30 is assembled to the connector 20 and then the valve 30 80 are pressed in.

The needle assembly 40 includes a needle 41 having a long diameter and a long length, an armature 42 fixed to the upper portion of the needle 41, and a cushion spring 43 inserted into the armature 42. [ A sleeve 44 which can move up and down on the needle 41 and a ball 45 which is attached to the lower end of the needle 41 and opens and closes the spray hole 81 of the valve seat 80.

The lower end of the sleeve 44 is formed to have a larger diameter than the diameter of the buffer spring mounting hole formed in the armature 42 so that the sleeve 44 is directly in contact with the upper surface of the armature 42 in a state where the buffer spring 43 is compressed to a predetermined amount or more have.

The armature 42 is formed with a through hole 42a in the up and down direction for smooth communication of the fuel.

A filter 90 is inserted into the upper body 10 to filter foreign matters contained in the fuel flowing into the injector.

There is a gap between the lower surface of the connector 20 and the upper surface of the armature 42 when the needle assembly 40 is lowered and the spray hole 81 is closed, Which is a valve lift (L).

In the normal state in which no current is supplied by the engine control unit, the needle assembly 40 is lowered by the urging force of the return spring 22 so that the ball 45 blocks the injection hole 81, It does not.

When the current is supplied by the engine control unit, the coil assembly 50 and the connector 20 (magnetic body) in contact therewith are energized, and the magnetic force generated in the connector 20 pulls the armature 42 upward, The ball 45 is separated from the valve seat 80 by injecting the fuel.

The buffer spring 43 compresses and expands between the sleeve 44 and the armature 42 when the needle assembly 40 is lifted or lowered so that the impact generated when the armature 42 impacts the connector 20 Thereby relieving the impact generated when the ball 45 collides against the valve seat 80.

On the other hand, in order to precisely control the fuel injection amount, it is necessary that the valve lift L is accurately set according to the design value. A difference may occur between the opening and closing timing of the injection hole 81 and the flow rate per unit time in accordance with the valve lift L and thus an error may occur in the control of the fuel injection amount and this may cause a decrease in the engine output and a decrease in fuel consumption and an increase in the amount of harmful exhaust gas .

In assembling the injector, a connection portion between the connector 20 and the carrier 30 and a connection portion between the carrier 30 and the valve seat 80 are welded. By the cooling and shrinking action after the welding operation, There is a problem that the injector does not have the valve lift L as designed by the change of the lift L.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel injection control system for an internal combustion engine, And an object thereof is to provide a method of assembling an injector.

According to another aspect of the present invention, there is provided a connector comprising: a carrier inserting step of inserting an upper end of a carrier into a lower end of a connector; a valve seat inserting step of inserting a valve seat into a lower end of the carrier; The upper portion of the carrier to be welded and the upper portion of the carrier are welded and the welded portions of the carrier and the valve seat are welded after the welds are completely cooled. By repeating the welding operation, the error of the valve lift is reduced, And a lower carrier welding step for setting the lower carrier.

And the welding performed in the upper carrier welding step and the lower carrier welding step is laser welding.

The lower carrier welding step includes a first valve lift measuring step of measuring the stroke distance of the needle assembly and a second valve lift measuring step of measuring the stroke of the valve lift by pressing the valve seat upward to bring the current valve lift value close to the design value, A first welding step of welding the carrier and the valve seat in a state in which the valve lift is in a lowered state and a second welding step of re-measuring the valve lift changed by the welding performed in the first welding step, And a second welding step of adjusting the welding strength by considering the difference between the valve lift value measured in the valve lift measuring step and the valve lift measured in the second valve lift measuring step and the design value.

The second welding step can perform a welding operation with a higher strength than the first welding step.

The second welding step can perform a welding operation with a lower strength than the first welding step.

And repeating the second valve lift measurement step and the second welding step again after the second welding step.

The measurement of the valve lift in the first valve lift measuring step and the second valve lift measuring step is performed by inserting a measuring pin abutting the upper end of the needle assembly into the interior of the injector and measuring a change in the upper position of the measuring pin.

According to the present invention as described above, the valve lift of the injector can be set accurately.

Therefore, the fuel injection quantity control of the engine is accurately performed, so that the engine output is improved, the fuel consumption is reduced, and the harmful exhaust gas emission amount is reduced.

1 is a cross-sectional view of an injector for explaining a configuration of an injector;
2 is a block diagram showing a configuration of a method of assembling an injector of an automobile engine according to the present invention.
3 is a block diagram showing a detailed configuration of a carrier bottom welding step which is an embodiment of the present invention;
Fig. 4 is a view showing a measurement pin installation state for explaining a method of measuring the valve lift of the injector. Fig.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The thicknesses of the lines and the sizes of the components shown in the accompanying drawings may be exaggerated for clarity and convenience of explanation.

In addition, the terms described below are defined in consideration of the functions of the present invention, and these may vary depending on the intention of the user, the operator, or the precedent. Therefore, definitions of these terms should be made based on the contents throughout this specification.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

First, the structure of an injector to which the present invention is applied will be briefly described with reference to FIG. As shown in FIG. 1, the inner body of the injector is formed by connecting the upper body 10, the connector 20, and the carrier 30, which are formed in a substantially cylindrical shape to form a passage through which the fuel passes.

The outer body on the outer side of the inner body is composed of a plastic housing 60 having a current connector 61 formed on an upper portion thereof and a metal housing 70 surrounding the outer periphery of the plastic housing 60. The plastic housing 60 is made of a non- The coil assembly 50 overmolds the coil assembly 50 that is in contact with the outer periphery of the inductor connector 20 and the coil assembly 50 is connected to the current connector 61 via electrical wires (connected through the interior of the plastic housing 60 It is connected.

In the connector 20, a cylindrical stopper 21 and a return spring 22 supporting the upper end of the stopper 21 are provided.

A needle assembly 40 is embedded in the carrier 30 and a valve seat 80 is inserted into the lower end of the carrier 30.

The needle assembly 40 is provided with an armature 42 on which an oil hole 42a is formed at the upper portion of a needle 41 and a ball 41 which opens and closes a spray hole 81 of the valve seat 80 at the lower end of the needle 41, And a sleeve 44 supported by a cushion spring 43 inserted into an installation hole of the armature 42 at the upper end of the needle 41. [

In the assembled state, the sleeve 44 is always forced downward in contact with the return spring 22.

The ball 45 of the needle assembly 40 lowered by the urging force of the return spring 22 contacts the valve seat 80 to block the injection hole 81 and the coil assembly 81 is inserted through the current connector 61, A magnetic force is generated in the connector 20 and the armature 42 is raised so that the needle 41 rises and the ball 45 opens the spray hole 81, .

The distance that the needle assembly 40 moves between the lowered position by the return spring 22 and the raised position by the energizing force of the coil assembly 50 is the valve lift L as described above. That is, the valve lift L is a gap between the upper surface of the armature 42 and the lower surface of the connector 20 in a state in which the needle assembly 40 is lowered (the ball 45 is in contact with the valve seat 80) It must be set to the design value in order to control the fuel injection quantity precisely.

2, the method for assembling an injector of an automobile engine according to the present invention for accurately setting the valve lift L as described above includes the steps of inserting the upper end of the carrier 30 into the outer periphery of the lower end of the connector 20 A valve seat insertion step S20 for inserting the valve seat 80 into the lower end of the carrier 30, a carrier upper welding step for welding the connection portion between the connector 20 and the carrier 30 (30) and the valve seat (80) are welded after the weld is completely cooled, and the error amount of the valve lift (L) through repetition of the welding operation (Step S40) in which the valve lift L is set to the design value by reducing the valve lift L.

The carrier connection step S10 connects the upper end of the carrier 30 to the lower end of the connector 20 and connects the upper end of the carrier 30 to the outer periphery of the lower end of the connector 20 to connect them. To this end, a connector insertion portion having a reduced diameter is formed on the outer periphery of the lower end of the connector 20, and the upper end of the carrier 30 is inserted into the connector insertion portion. However, the needle assembly 40 must be inserted into the carrier 30 before the carrier connection step S10 is performed. The needle assembly 40 includes an armature 42 having a larger diameter than the lower end opening of the carrier 30 so that the carrier 30 is connected to the connector 20 and then is inserted through the lower end opening of the carrier 30, It is not possible to insert the insertion portion 40.

Also, it is preferable that the stopper 21 and the return spring 22 in the connector 20 are also installed before the carrier connection step S10.

It is also preferable that the upper body connecting step of connecting the upper body 10 to the upper end of the connector 20 before the carrier connection step S10 is performed first. At this time, the filter 90 is not provided on the inner diameter portion of the upper body 10. The reason why the filter 90 is not provided is that the measurement pin 100 used when measuring the valve lift L due to the valve lift measurement steps S41 and S44 included in the lower carrier welding step S40 to be described later, Is inserted through the upper body 10 (see Fig. 4)

The valve seat inserting step S20 is a step of inserting the cylindrical valve seat 80 into the lower end opening inner diameter of the carrier 30 so that the inner diameter of the lower end of the carrier 30 is small enough to press the valve seat 80 Extensively molded compared to other parts.

The valve seat 80 is formed in a cylindrical shape with an open top and an inner bottom surface is formed in a conical shape so that the ball 45 of the needle assembly 40 can be seated and a spray hole 81 is formed at the vertex of the conical shape do. The position and number of the injection holes 81 can be changed if the injection hole 81 is only opened and closed by the contact between the ball 45 and the inner surface of the conical upper part.

After the carrier 30 and the valve seat 80 are assembled together through the carrier connection step S10 and the valve seat inserting step S20 as described above, the upper carrier welding step S30 is performed.

In the upper carrier welding step S30, the connector 20 and the carrier 30 are welded together to fix the connector 20 and the carrier 30 to each other.

It is preferable to perform laser welding in order to minimize heat input to the material by welding. In addition, laser welding is useful in the sub-carrier welding step (S40), which will be described later, because it is easy to control the welding strength by adjusting the intensity and irradiation time of the laser beam.

As the heat input by welding is minimized, the influence of the expansion of the component to be welded due to heat and the contraction during cooling after expansion can be reduced. Generally, the portion heated during welding tends to undergo shrinkage deformation due to welding residual stress.

In the lower carrier welding step S40, the connection portion between the carrier 30 and the valve seat 80 is welded to fix the valve seat 80 to the carrier 30.

It is preferable to perform laser welding in order to minimize the amount of cooling shrinkage after thermal expansion as in the upper carrier welding step S30.

On the other hand, when laser welding is performed in the same manner, since the circumferential circumference of the lower welded portion is smaller than the upper welded portion of the carrier 30, the welding area is small and the heat input applied at the welding is smaller than the upper portion. (S30) is first carried out, and after the welding part is completely cooled, proceeding to the sub-carrier welding step (S40) helps to set the valve lift L accurately by reducing the amount of change of the valve lift L .

The lower carrier welding step S40 is performed for a predetermined time after the upper carrier welding step S30 as described above so that the welding operation performed in the upper carrier welding step S30 does not affect the valve lift L And after the weld has completely cooled down.

The lower carrier welding step S40 may include a first valve lift measuring step S41, a valve lift pressing step S42, a first welding step S43, a second valve lift measuring step S44), a second welding step (S45) and an iteration step (S46).

The first valve lift measuring step (S41) is performed after the upper carrier welding step (S30) is performed and the welded part is completely cooled. The measurement of the valve lift L is performed by inserting the measuring pin 100 through the upper body 10 so that the lower end of the measuring pin 100 is brought into contact with the upper end of the needle 41 The position of the upper end of the measuring pin 100 raised by raising the needle assembly 40 by exciting the upper end of the measuring pin 100 and the coil assembly 50 at that time is measured and the difference between the two position values is calculated . The measuring pin 100 is a circular rod having a diameter that can be inserted into the inside of the injector. (Separate measuring instrument for detecting the position of the upper end of the measuring pin 100 is not shown)

When the valve lift L is measured in the above-described manner, in the valve lift pressing step S42, the needle assembly 40 is moved upward by an amount close to the difference between the valve lift L design value and the measured value. That is, the valve seat 80 is pressed upward so that the valve lift L is slightly less than the correct valve lift setting position.

The margin value (the difference between the valve lift design value and the adjustment value) considered in the valve lift pressing step S42 is gradually reduced through the subsequent welding step.

When the valve seat 80 is pressed upward, the needle assembly 40 abutting against the valve seat 80 moves upward, so that the measuring pin 100 abutting on the needle 41 is moved upward, ), The upper press-in amount of the valve seat 80 can be determined by measuring and comparing the upper surface height.

In this manner, the valve lift L can be appropriately leveled by measuring the valve lift L and adjusting the upward press-fitting amount of the valve seat 80.

Then, a first welding step S43 is performed. In the first welding step S43, a laser beam is irradiated along the circumferential direction to the connecting portion of the carrier 30 and the valve seat 80 to perform laser welding. Through the first welding step (S43), the valve seat (80) is fully engaged with the carrier (30), ensuring sufficient bonding strength and tightness.

A second valve lift measuring step S44 for measuring the valve lift L again after a lapse of a time after the first welding step S43 (which means that the welded part is completely cooled at room temperature by natural cooling at room temperature) .

As described above, after welding, the valve lift L is always changed in the decreasing direction by the shrinking deformation of the welded portion. That is, after welding, the gap distance between the lower surface of the connector 20 and the upper surface of the armature 42 is always reduced.

Therefore, the second valve lift measuring step S44 is performed to measure the valve lift L again. The method of measuring the valve lift (L) is the same as the method performed in the first valve lift measuring step (S41).

The difference between the value of the valve lift L measured through the second valve lift measuring step S44 and the value of the valve lift L designates the difference between the design value measured in the first valve lift measuring step S41 and the measured value , The second welding step S45 is performed.

The second welding step (S45) performs the same welding operation as the welding operation performed in the first welding step (S43), but the welding operation in this step is performed in the same manner as the welding operation performed in the first welding step (S43) It is preferable to reduce the intensity of the laser beam or reduce the irradiation time of the laser beam to reduce the welding strength, that is, the heating amount. This is to prevent the value of the valve lift L from exceeding the designed value by the second welding step (S45) by excessively reducing the valve lift (L) value after thermal expansion and cooling shrink due to welding.

After the second welding step S45 as described above, the valve lift L is measured and if it is not set to the designed value, the second valve lift measuring step S44 and the second welding step S45 are repeatedly performed Repeat step S46 is performed.

The repetition step (S46) repeats measurement and welding until the valve lift (L) measurement value equals the design value (until it falls within the allowable reference range), and as the number of repetitions increases, It is preferable to gradually decrease the welding strength in order to prevent the welding strength from decreasing to a small value.

On the other hand, in performing the sub-carrier welding step S40, in the welding operation repeated after the second welding step S45, the strength of the subsequent welding operation does not necessarily have to be lower than that of the preceding welding operation. Considering the reduced valve lift value and the allowance to the design value after the preceding welding operation, if it is deemed that more heat is needed than that of the preceding welding operation, the strength of the subsequent welding operation can be made stronger than the welding strength in the preceding welding operation Of course it is.

By using the method according to the present invention as described above, it is possible to accurately set the valve lift of the injector, thereby improving the fuel injection control performance of the injector and thereby improving the output of the engine, reducing fuel consumption and reducing harmful substances. .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is understandable. Accordingly, the true scope of the present invention should be determined by the following claims.

10: upper body 20: connector
30: Carrier 40: Needle assembly
50: coil assembly 60: plastic housing
70: metal housing 80: valve seat
90: filter 100: measuring pin

Claims (7)

A carrier inserting step of inserting an upper end of the carrier into a lower outer periphery of the connector;
A valve seat inserting step of inserting the valve seat into the lower end of the carrier;
A carrier upper welding step of welding a connector and a connection portion of a carrier;
The upper portion of the carrier is welded and the welded portion is completely cooled, the connection portion of the carrier and the valve seat is welded, and the error amount of the valve lift is reduced through repetition of the welding operation, Welding step;
Wherein the injector has a plurality of projections. The method according to claim 1,
Wherein the welding performed in the upper carrier welding step and the lower carrier welding step is laser welding. The method according to claim 1,
Wherein the lower carrier welding step comprises:
A first valve lift measuring step of measuring the stroke distance of the needle assembly;
A valve lift pressing step of pressing the valve seat upward so as to approximate the valve lift so that the current valve lift value approaches the design value in consideration of the valve lift measurement value;
A first welding step of welding the carrier and the valve seat in a state in which the valve lift is being asserted;
A second valve lift measuring step of remeasuring the valve lift changed by the welding performed in the first welding step;
A second welding step of adjusting the welding strength in consideration of the difference between the valve lift value and the design value measured in the second valve lift measuring step to perform a welding operation;
And injecting fuel into the injector. The method of claim 3,
Wherein the second welding step performs a welding operation with a higher strength than the first welding step. The method of claim 3,
Wherein the second welding step performs a welding operation with a lower strength than the first welding step. The method according to any one of claims 3 to 5,
And repeating the second valve lift measurement step and the second welding step again after the second welding step. The method of claim 3,
The measurement of the valve lift in the first valve lift measuring step and the second valve lift measuring step is performed by inserting a measuring pin abutting the upper end of the needle assembly into the interior of the injector and measuring a change in the upper position of the measuring pin Of the injector (10).

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