JPH0697020B2 - Injector - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an injector for an electronically controlled fuel injection device, particularly for use in a gasoline engine.

(Prior Art) In recent years, in a vehicle equipped with a gasoline engine, as a fuel injection device, improvement in fuel consumption, improvement in engine output characteristics,
Electronically controlled fuel injection devices are being adopted in order to improve the purification of exhaust gas.

This electronically controlled fuel injection is a method of injecting fuel, which is normally kept at a constant pressure, into the intake pipe, and the injection amount is controlled by using an electromagnetic injection valve (hereinafter referred to as an injector) for intake air per cycle of the engine. It is an intermittent injection method that opens for a certain time according to the amount. That is, since the injection amount is determined only by the time of the electric pulse applied to the injector, the fuel control can be performed easily and with high accuracy. Furthermore, since all the operating conditions of the engine are converted into electric signals, the degree of freedom in adaptation is high, and correction elements can be easily added.

The injector is driven by the cooperation of a housing, a valve body mounted on the tip of the housing, a solenoid housed in the housing, and a slidably inserted in the valve body and an electromagnetic force of the solenoid and a spring. A needle valve connected to the plunger, and when an electric pulse is applied to the solenoid, the plunger is attracted and moved against the spring force of the spring, and the needle valve is opened accordingly. Then, the fuel is injected from the injection port of the valve body, and the injection rate of the fuel is determined by the fuel pressure and the annular gap between the tip of the needle valve and the injection port of the valve body.

In order to improve the durability of such injectors, normally, valve bodies, needle valves, etc. are formed from stainless steel such as SUS304, which has corrosion resistance and wear resistance, and further heat treated to harden the surface to increase the hardness. There is.

(Problems to be solved by the invention) However, as shown by the broken line in the characteristic diagram of FIG. 2, the stainless steel such as SUS304 is magnetically attached with cutting chips as shown in the broken line in FIG. Adversely affect processing accuracy, airtightness test, flow rate setting, etc. Further, when the stainless steel is heat-treated and hardened, the structure becomes martensite and becomes magnetic, and the needle valve is magnetized under the influence of the magnetic field of the solenoid when the injector is in operation. Iron powder generated due to wear at the sliding part between the needle valve and valve body during operation is attracted and adhered to the moving parts of these needle valves and the nozzle body of the valve body, etc. Deteriorate, or the suction or separation action occurs between the needle valve and the valve body, and the needle valve does not operate smoothly.Furthermore, the residual magnetism of the needle valve deteriorates the injector control characteristics. I have a problem.

The present invention has been made to solve the above-mentioned problems, and at least the needle valve is made non-magnetic to prevent the adhesion of iron powder, eliminate the adverse effect of the solenoid's magnetic field, and further improve corrosion resistance and wear resistance. The purpose is to provide an injector.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, the electromagnetic force of a solenoid and a spring are slidably inserted in a valve body mounted at the tip of a housing. In an injector with a needle valve driven by the action of
At least the needle valve, Mn 17.50 ~ 18.50 wt%, and Cr is formed from 14.00 ~ 17.00 wt% high manganese non-magnetic steel material having corrosion resistance and wear resistance,
The surface is subjected to a nitriding treatment.

(Operation) The iron powder is prevented from adhering to the needle valve, and the attraction or separation between the needle valve and the valve body due to the magnetic field of the solenoid is prevented. This facilitates the operation of the needle valve.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a cross section of an injector to which the present invention is applied,
A valve body 4 is attached and fixed to a tip of a housing 2 forming an outer shell of the injector 1 via a stopper 3.
Moreover, the valve body 4 is liquid-tightly mounted on the housing 2 via the seal member 5. Further, a cap 6 is attached and fixed to the tip of the valve body 4. A solenoid 9 is provided in the housing 2 via seal members 7 and 8.
The bobbin 10 wound around is inserted. Housing 2
A holder 11 is attached to the rear end of the
a is fitted into the housing 2 and into the shaft hole of the bobbin 10 via a seal member 12, the central portion 11b is firmly caulked and fixed to the open end of the housing 2, and the other end 11c is located outside the housing 2. It is connected to a fuel hose (not shown) through the protruding seal member 13.

A fuel passage 11d is provided through the shaft center of the holder 11, and the passage 1
A cylindrical stopper 14 is fitted and fixed in the approximate center of 1d. Further, a connector 15 is attached and fixed to the center of the holder 11, and the connection end of the solenoid 9 is connected to the connector 15. The connector 15 is connected to an electronically controlled fuel injection device (not shown).

In the housing 2, a plunger 20 having a fuel passage 20a extending axially between a stopper 3 and a bobbin 10 is axially slidably fitted and one end of which is fitted in a hole 2a of the housing 2. The other end of the bobbin 10 can be inserted into and removed from the one open end of the bobbin 10, and a spring 21 is contracted between the other end and the facing end surface of the stopper 12 in the holder 11.

The needle valve 22 is slidably fitted in a hole 5a penetrating the shaft core of the valve body 5, and its tip 22a freely penetrates the injection hole 5b bored in the tip of the valve body 5 with a slight gap. And further penetrates the injection hole 6a of the cap 6 to form an end face 22b.
Contacts the valve seat 5c of the valve body 5. The shaft portion 22c of the needle valve 22 has a slightly smaller diameter than the hole 5a of the valve body 5, and the large diameter portions 22d and 22e formed at both ends of the shaft portion 22c are slidably fitted into the hole 5a of the valve body 5. In addition, each of the large diameter portions 22d and 22e has its peripheral surface cut equally into four surfaces in the circumferential direction. A fuel passage is formed between the cut surfaces of the large diameter portions 22d and 22e and the inner peripheral surface of the hole 5a of the valve body 5.

The rear end 22f of the needle valve 22 freely penetrates the hole 3a of the stopper 3 and projects toward the plunger 20, and is fixedly attached to one end of the plunger 20 facing the plunger 20. A rear end 22f of the needle valve 22 is formed with a hole 22g in the shaft center, and an opening end of the hole 22g communicates with the hole 20a of the plunger 20 and a plurality of side walls are formed near the bottom end of the hole. It is opened to the outside through the hole 22h.

The valve body 5 and the needle valve 22 are made of non-magnetic steel material having corrosion resistance and wear resistance. Examples of such non-magnetic steel materials include those having a chemical composition as shown in Table 1.

These non-magnetic steel materials are subjected to a surface treatment to harden the surface without giving magnetism and in order to further improve wear resistance. As such surface treatment, ion carbonitriding,
There are various treatment methods such as ion nitriding, gas nitriding, and tufftride treatment.

In this embodiment, the valve body 5 and the needle valve
PCD18 shown in Table 1 is used as a steel material forming 22 and is subjected to ion nitriding as a surface treatment. This steel
PCD18 has the magnetic characteristics shown by the solid line in FIG. 2 and does not become magnetized even if it is processed.

Further, since this non-magnetic steel material PCD18 contains Mn, it is hard and has excellent wear resistance, and when processed, the grace strength is improved. Furthermore, the surface treatment (nitriding) improves wear resistance,
Moreover, non-magnetism is stable. Furthermore, since it contains a large amount of Cr, it is extremely excellent in rust resistance. Moreover, since the chemical composition is as shown in Table 1, the material price does not become expensive.

The other housing 2, holder 11, plunger 20, etc. are made of the same members as the conventional injector.

The operation will be described below.

When the solenoid 9 is deenergized, the spring 21 pushes the plunger 20 out of the bobbin 10 by the spring force as shown in the drawing, pushes out the needle valve 22, presses the end face 22b against the valve seat 5c of the valve body 5, and presses the injection hole 5b. Block. As a result, the injector 1 is closed. On the other hand, fuel is supplied to the holder through the hose (not shown).
It is supplied under pressure into the fuel passage 11d of 11, and the plunger 2
0, the passages 20a, 22g, 22h of the needle valve 22, the hole 3a of the stopper 3, the hole 5a of the valve holder 5 and the cut surfaces of the large diameter portion 22f of the needle valve 22, the shaft portion 22c, and the large diameter portion 22d. It is supplied at a predetermined fuel pressure into the oil reservoir chamber 23 at the tip of the valve body 5 through each gap between each cut surface.

When the solenoid 9 is energized by the electronically controlled fuel injection device, the plunger 20 is attracted against the spring force of the spring 21 by its electromagnetic force while the solenoid 9 is energized, and one end thereof is bobbin-shaped. Pulled in within 10. Along with this, the needle valve 22 moves to the right in the drawing until the land 22i is brought into contact with the stopper 3 and locked, and the end face 22b
Is separated from the valve seat 5c of the valve body 5 by the injection hole 5b.
To open. As a result, the fuel in the oil reservoir chamber 23 is injected into the fuel chamber of the cylinder (not shown) through the injection holes 5b due to the fuel pressure.

By the way, since the valve body 5 and the needle valve 22 are formed of a non-magnetic member, even if the solenoid coil 9 is energized to generate a magnetic field, it is not magnetized by the magnetic field and has no residual magnetism. Therefore, the action such as attraction or separation due to the magnetic force does not occur between the two as described above, and the two can operate smoothly. Furthermore, valve body 5 and needle valve 22
As described above, since it is formed of a steel material having excellent corrosion resistance and wear resistance, the wear thereof is extremely small and the generation of the iron powder due to the operation of the needle valve 22 can be greatly suppressed. As a result, the injector 1 operates well,
Good fuel injection.

In this embodiment, the case where both the valve body and the needle valve are made of the non-magnetic member has been described, but the present invention is not limited to this, and only the needle valve may be made of the non-magnetic member. .

(Effect of the Invention) As described above, according to the present invention, a needle valve which is slidably inserted in a valve body mounted on the tip of a housing and is driven by the cooperation of an electromagnetic force of a solenoid and a spring is provided. In the injector provided, at least the needle valve has an Mn of 17.50 to 18.50% by weight,
And formed from a high-manganese non-magnetic steel material containing 14.00 to 17.00 wt% Cr and having corrosion resistance and wear resistance, and by nitriding the surface of the high-manganese steel material, the needle valve and the solenoid of the valve body The attraction or separation between the two due to the magnetic force caused by the magnetic field is eliminated, the operation of the needle valve is smoothed, and the adverse effect on the control characteristics due to the residual magnetism of the needle valve is prevented, and the injector is operated very well. It becomes possible.

Furthermore, due to the operation of the needle valve, the generation of iron powder in the sliding portion between the needle valve and the valve body is significantly suppressed, and, in combination with the non-magnetization, the needle valve of the iron powder is It is possible to prevent the sliding portion and the valve body from adhering to the injection port and the like, and accordingly, the needle valve can be operated smoothly and the fuel injection characteristics can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of an injector according to the present invention, and FIG. 2 is an embodiment of magnetic characteristics of a non-magnetic steel material used for a needle valve of the injector according to the present invention. It is a graph which shows. 2 ... Housing, 4 ... Valve body, 9 ... Solenoid, 11 ... Holder, 20 ... Plunger, 22 ... Needle valve.

Claims (1)

[Claims] 1. An injector comprising a needle valve slidably fitted in a valve body mounted on the tip of a housing and driven by the cooperation of an electromagnetic force of a solenoid and a spring, wherein at least the needle valve comprises: It is formed of a high-manganese non-magnetic steel material containing 17.50 to 18.50% by weight of Mn and 14.00 to 17.00% by weight of Cr and having corrosion resistance and wear resistance, and its surface is subjected to nitriding treatment. The injector to do.